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+publicationDate,title,abstract,id
+2008-04-04,Inhomogeneous Gilbert damping from impurities and electron-electron interactions,"We present a unified theory of magnetic damping in itinerant electron
+ferromagnets at order $q^2$ including electron-electron interactions and
+disorder scattering. We show that the Gilbert damping coefficient can be
+expressed in terms of the spin conductivity, leading to a Matthiessen-type
+formula in which disorder and interaction contributions are additive. In a weak
+ferromagnet regime, electron-electron interactions lead to a strong enhancement
+of the Gilbert damping.",0804.0820v2
+2006-12-01,Gilbert damping and spin Coulomb drag in a magnetized electron liquid with spin-orbit interaction,"We present a microscopic calculation of the Gilbert damping constant for the
+magnetization of a two-dimensional spin-polarized electron liquid in the
+presence of intrinsic spin-orbit interaction. First we show that the Gilbert
+constant can be expressed in terms of the auto-correlation function of the
+spin-orbit induced torque. Then we specialize to the case of the Rashba
+spin-orbit interaction and we show that the Gilbert constant in this model is
+related to the spin-channel conductivity. This allows us to study the Gilbert
+damping constant in different physical regimes, characterized by different
+orderings of the relevant energy scales -- spin-orbit coupling, Zeeman
+coupling, momentum relaxation rate, spin-momentum relaxation rate, spin
+precession frequency -- and to discuss its behavior in various limits.
+Particular attention is paid to electron-electron interaction effects,which
+enter the spin conductivity and hence the Gilbert damping constant via the spin
+Coulomb drag coefficient.",0612015v1
+2011-09-22,Hole spin relaxation and coefficients in Landau-Lifshitz-Gilbert equation in ferromagnetic GaMnAs,"We investigate the temperature dependence of the coefficients in the
+Landau-Lifshitz-Gilbert equation in ferromagnetic GaMnAs by employing the Zener
+model. We first calculate the hole spin relaxation time based on the
+microscopic kinetic equation. We find that the hole spin relaxation time is
+typically several tens femtoseconds and can present a nonmonotonic temperature
+dependence due to the variation of the interband spin mixing, influenced by the
+temperature related Zeeman splitting. With the hole spin relaxation time, we
+are able to calculate the coefficients in the Landau-Lifshitz-Gilbert equation,
+such as the Gilbert damping, nonadiabatic spin torque, spin stiffness and
+vertical spin stiffness coefficients. We find that the nonadiabatic spin torque
+coefficient $\beta$ is around $0.1\sim 0.3$ at low temperature, which is
+consistent with the experiment [Adam {\em et al.}, Phys. Rev. B {\bf 80},
+193204 (2009)]. As the temperature increases, $\beta$ monotonically increases
+and can exceed one in the vicinity of the Curie temperature. In the low
+temperature regime with $\beta<1$, the Gilbert damping coefficient $\alpha$
+increases with temperature, showing good agreement with the experiments [Sinova
+{\em et al.}, Phys. Rev. B {\bf 69}, 085209 (2004); Khazen {\em et al.}, {\em
+ibid.} {\bf 78}, 195210 (2008)]. Furthermore, we predict that $\alpha$
+decreases with increasing temperature once $\beta>1$ near the Curie
+temperature. We also find that the spin stiffness decreases with increasing
+temperature, especially near the Curie temperature due to the modification of
+the finite $\beta$. Similar to the Gilbert damping, the vertical spin stiffness
+coefficient is also found to be nonmonotonically dependent on the temperature.",1109.4964v1
+2002-02-11,Radiation Induced Landau-Lifshitz-Gilbert Damping in Ferromagnets,"The Landau-Lifshitz-Gilbert damping coefficient employed in the analysis of
+spin wave ferromagnetic resonance is related to the electrical conductivity of
+the sample. The changing magnetization (with time) radiates electromagnetic
+fields. The electromagnetic energy is then absorbed by the sample and the
+resulting heating effect describes magnetic dissipative damping. The
+ferromagnetic resonance relaxation rate theoretically depends on the geometry
+(shape and size) of the sample as well as temperature in agreement with
+experiment.",0202181v1
+2008-08-09,Gilbert Damping in Conducting Ferromagnets I: Kohn-Sham Theory and Atomic-Scale Inhomogeneity,"We derive an approximate expression for the Gilbert damping coefficient
+\alpha_G of itinerant electron ferromagnets which is based on their description
+in terms of spin-density-functional-theory (SDFT) and Kohn-Sham quasiparticle
+orbitals. We argue for an expression in which the coupling of magnetization
+fluctuations to particle-hole transitions is weighted by the spin-dependent
+part of the theory's exchange-correlation potential, a quantity which has large
+spatial variations on an atomic length scale. Our SDFT result for \alpha_G is
+closely related to the previously proposed spin-torque correlation-function
+expression.",0808.1373v1
+2003-09-29,Damping rates of the atomic velocity in Sisyphus cooling,"We present a theoretical and experimental study of the damping process of the
+atomic velocity in Sisyphus cooling. The relaxation rates of the atomic kinetic
+temperature are determined for a 3D lin$\perp$lin optical lattice. We find that
+the damping rates of the atomic temperature depend linearly on the optical
+pumping rate, for a given depth of the potential wells. This is at variance
+with the behavior of the friction coefficient as calculated from the spatial
+diffusion coefficients within a model of Brownian motion. The origin of this
+different behavior is identified by distinguishing the role of the trapped and
+traveling atoms.",0309209v1
+2012-11-15,Spin transport and tunable Gilbert damping in a single-molecule magnet junction,"We study time-dependent electronic and spin transport through an electronic
+level connected to two leads and coupled with a single-molecule magnet via
+exchange interaction. The molecular spin is treated as a classical variable and
+precesses around an external magnetic field. We derive expressions for charge
+and spin currents by means of the Keldysh non-equilibrium Green's functions
+technique in linear order with respect to the time-dependent magnetic field
+created by this precession. The coupling between the electronic spins and the
+magnetization dynamics of the molecule creates inelastic tunneling processes
+which contribute to the spin currents. The inelastic spin currents, in turn,
+generate a spin-transfer torque acting on the molecular spin. This back-action
+includes a contribution to the Gilbert damping and a modification of the
+precession frequency. The Gilbert damping coefficient can be controlled by the
+bias and gate voltages or via the external magnetic field and has a
+non-monotonic dependence on the tunneling rates.",1211.3611v2
+2021-05-08,A second-order numerical method for Landau-Lifshitz-Gilbert equation with large damping parameters,"A second order accurate numerical scheme is proposed and implemented for the
+Landau-Lifshitz-Gilbert equation, which models magnetization dynamics in
+ferromagnetic materials, with large damping parameters. The main advantages of
+this method are associated with the following features: (1) It only solves
+linear systems of equations with constant coefficients where fast solvers are
+available, so that the numerical efficiency has been greatly improved, in
+comparison with the existing Gauss-Seidel project method. (2) The second-order
+accuracy in time is achieved, and it is unconditionally stable for large
+damping parameters. Moreover, both the second-order accuracy and the great
+efficiency improvement will be verified by several numerical examples in the 1D
+and 3D simulations. In the presence of large damping parameters, it is observed
+that this method is unconditionally stable and finds physically reasonable
+structures while many existing methods have failed. For the domain wall
+dynamics, the linear dependence of wall velocity with respect to the damping
+parameter and the external magnetic field will be obtained through the reported
+simulations.",2105.03576v1
+2017-09-29,Non-local Gilbert damping tensor within the torque-torque correlation model,"An essential property of magnetic devices is the relaxation rate in magnetic
+switching which depends strongly on the damping in the magnetisation dynamics.
+It was recently measured that damping depends on the magnetic texture and,
+consequently, is a non-local quantity. The damping enters the
+Landau-Lifshitz-Gilbert equation as the phenomenological Gilbert damping
+parameter $\alpha$, that does not, in a straight forward formulation, account
+for non-locality. Efforts were spent recently to obtain Gilbert damping from
+first principles for magnons of wave vector $\mathbf{q}$. However, to the best
+of our knowledge, there is no report about real space non-local Gilbert damping
+$\alpha_{ij}$. Here, a torque-torque correlation model based on a tight binding
+approach is applied to the bulk elemental itinerant magnets and it predicts
+significant off-site Gilbert damping contributions, that could be also
+negative. Supported by atomistic magnetisation dynamics simulations we reveal
+the importance of the non-local Gilbert damping in atomistic magnetisation
+dynamics. This study gives a deeper understanding of the dynamics of the
+magnetic moments and dissipation processes in real magnetic materials. Ways of
+manipulating non-local damping are explored, either by temperature, material's
+doping or strain.",1709.10365v1
+2008-07-18,Current-induced dynamics of spiral magnet,"We study the dynamics of the spiral magnet under the charge current by
+solving the Landau-Lifshitz-Gilbert equation numerically. In the steady state,
+the current ${\vec j}$ induces (i) the parallel shift of the spiral pattern
+with velocity $v=(\beta/\alpha)j$ ($\alpha$, $\beta$: the Gilbert damping
+coefficients), (ii) the uniform magnetization $M$ parallel or anti-parallel to
+the current depending on the chirality of the spiral and the ratio $\beta /
+\alpha $, and (iii) the change in the wavenumber $k$ of the spiral. These are
+analyzed by the continuum effective theory using the scaling argument, and the
+various nonequilibrium phenomena such as the chaotic behavior and
+current-induced annealing are also discussed.",0807.2901v1
+2010-03-19,Dynamics of magnetization on the topological surface,"We investigate theoretically the dynamics of magnetization coupled to the
+surface Dirac fermions of a three dimensional topological insulator, by
+deriving the Landau-Lifshitz-Gilbert (LLG) equation in the presence of charge
+current. Both the inverse spin-Galvanic effect and the Gilbert damping
+coefficient $\alpha$ are related to the two-dimensional diagonal conductivity
+$\sigma_{xx}$ of the Dirac fermion, while the Berry phase of the ferromagnetic
+moment to the Hall conductivity $\sigma_{xy}$. The spin transfer torque and the
+so-called $\beta$-terms are shown to be negligibly small. Anomalous behaviors
+in various phenomena including the ferromagnetic resonance are predicted in
+terms of this LLG equation.",1003.3769v1
+2016-02-23,Experimental Investigation of Temperature-Dependent Gilbert Damping in Permalloy Thin Films,"The Gilbert damping of ferromagnetic materials is arguably the most important
+but least understood phenomenological parameter that dictates real-time
+magnetization dynamics. Understanding the physical origin of the Gilbert
+damping is highly relevant to developing future fast switching spintronics
+devices such as magnetic sensors and magnetic random access memory. Here, we
+report an experimental study of temperature-dependent Gilbert damping in
+permalloy (Py) thin films of varying thicknesses by ferromagnetic resonance.
+From the thickness dependence, two independent contributions to the Gilbert
+damping are identified, namely bulk damping and surface damping. Of particular
+interest, bulk damping decreases monotonically as the temperature decreases,
+while surface damping shows an enhancement peak at the temperature of ~50 K.
+These results provide an important insight to the physical origin of the
+Gilbert damping in ultrathin magnetic films.",1602.07325v1
+2019-02-22,Strongly Enhanced Gilbert Damping in 3d Transition Metal Ferromagnet Monolayers in Contact with Topological Insulator Bi2Se3,"Engineering Gilbert damping of ferromagnetic metal films is of great
+importance to exploit and design spintronic devices that are operated with an
+ultrahigh speed. Based on scattering theory of Gilbert damping, we extend the
+torque method originally used in studies of magnetocrystalline anisotropy to
+theoretically determine Gilbert dampings of ferromagnetic metals. This method
+is utilized to investigate Gilbert dampings of 3d transition metal ferromagnet
+iron, cobalt and nickel monolayers that are contacted by the prototypical
+topological insulator Bi2Se3. Amazingly, we find that their Gilbert dampings
+are strongly enhanced by about one order in magnitude, compared with dampings
+of their bulks and free-standing monolayers, owing to the strong spin-orbit
+coupling of Bi2Se3. Our work provides an attractive route to tailoring Gilbert
+damping of ferromagnetic metallic films by putting them in contact with
+topological insulators.",1902.08700v1
+2018-08-20,Gilbert damping of [Co/Pd]n/Py multilayer thin films,"Understanding the Gilbert damping in exchange-coupled multilayer materials is
+particularly important to develop future fast switching spintronics devices.
+Here, we report an experimental investigation of temperature-dependent Gilbert
+damping in [Co/Pd]n/Py multilayer films of varying the number of Co/Pd
+repetitions by ferromagnetic resonance. The results demonstrate that three
+independent contributions to the Gilbert damping are identified, namely the
+intrinsic Gilbert damping, the inhomogeneous linewidth broadening and the
+two-magnon scattering contribution. Of particular interest, the two-magnon
+scattering intensity increases as the enlargement of number repetitions of
+Co/Pd due to the larger pinning effect at the interface between Py and the
+Co/Pd layers. The Gilbert damping increases monotonically as the temperature
+decreases from 300K to 50K. Our findings open the door to comprehend the
+physical origin of the Gilbert damping in ultrathin exchange-coupled multilayer
+films.",1808.06515v2
+2006-10-10,Spin-transfer in an open ferromagnetic layer: from negative damping to effective temperature,"Spin-transfer is a typical spintronics effect that allows a ferromagnetic
+layer to be switched by spin-injection. Most of the experimental results about
+spin transfer are described on the basis of the Landau-Lifshitz-Gilbert
+equation of the magnetization, in which additional current-dependent damping
+factors are added, and can be positive or negative. The origin of the damping
+can be investigated further by performing stochastic experiments, like one shot
+relaxation experiments under spin-injection in the activation regime of the
+magnetization. In this regime, the N\'eel-Brown activation law is observed
+which leads to the introduction of a current-dependent effective temperature.
+In order to justify the introduction of these counterintuitive parameters
+(effective temperature and negative damping), a detailed thermokinetic analysis
+of the different sub-systems involved is performed. We propose a thermokinetic
+description of the different forms of energy exchanged between the electric and
+the ferromagnetic sub-systems at a Normal/Ferromagnetic junction. The
+corresponding Fokker Planck equations, including relaxations, are derived. The
+damping coefficients are studied in terms of Onsager-Casimir transport
+coefficients, with the help of the reciprocity relations. The effective
+temperature is deduced in the activation regime.",0610264v1
+2016-07-18,Magnetic Skyrmion Transport in a Nanotrack With Spatially Varying Damping and Non-adiabatic Torque,"Reliable transport of magnetic skyrmions is required for any future
+skyrmion-based information processing devices. Here we present a micromagnetic
+study of the in-plane current-driven motion of a skyrmion in a ferromagnetic
+nanotrack with spatially sinusoidally varying Gilbert damping and/or
+non-adiabatic spin-transfer torque coefficients. It is found that the skyrmion
+moves in a sinusoidal pattern as a result of the spatially varying Gilbert
+damping and/or non-adiabatic spin-transfer torque in the nanotrack, which could
+prevent the destruction of the skyrmion caused by the skyrmion Hall effect. The
+results provide a guide for designing and developing the skyrmion transport
+channel in skyrmion-based spintronic applications.",1607.04983v3
+2003-08-19,"Magnetization relaxation in (Ga,Mn)As ferromagnetic semiconductors","We describe a theory of Mn local-moment magnetization relaxation due to p-d
+kinetic-exchange coupling with the itinerant-spin subsystem in the
+ferromagnetic semiconductor (Ga,Mn)As alloy. The theoretical Gilbert damping
+coefficient implied by this mechanism is calculated as a function of Mn moment
+density, hole concentration, and quasiparticle lifetime. Comparison with
+experimental ferromagnetic resonance data suggests that in annealed strongly
+metallic samples, p-d coupling contributes significantly to the damping rate of
+the magnetization precession at low temperatures. By combining the theoretical
+Gilbert coefficient with the values of the magnetic anisotropy energy, we
+estimate that the typical critical current for spin-transfer magnetization
+switching in all-semiconductor trilayer devices can be as low as $\sim 10^{5}
+{\rm A cm}^{-2}$.",0308386v3
+2007-08-24,Enhancement of the Gilbert damping constant due to spin pumping in noncollinear ferromagnet/nonmagnet/ferromagnet trilayer systems,"We analyzed the enhancement of the Gilbert damping constant due to spin
+pumping in non-collinear ferromagnet / non-magnet / ferromagnet trilayer
+systems. We show that the Gilbert damping constant depends both on the
+precession angle of the magnetization of the free layer and on the direction of
+the magntization of the fixed layer. We find the condition to be satisfied to
+realize strong enhancement of the Gilbert damping constant.",0708.3323v1
+2017-06-14,Temperature-dependent Gilbert damping of Co2FeAl thin films with different degree of atomic order,"Half-metallicity and low magnetic damping are perpetually sought for in
+spintronics materials and full Heusler alloys in this respect provide
+outstanding properties. However, it is challenging to obtain the well-ordered
+half-metallic phase in as-deposited full Heusler alloys thin films and theory
+has struggled to establish a fundamentals understanding of the temperature
+dependent Gilbert damping in these systems. Here we present a study of the
+temperature dependent Gilbert damping of differently ordered as-deposited
+Co2FeAl full Heusler alloy thin films. The sum of inter- and intraband electron
+scattering in conjunction with the finite electron lifetime in Bloch states
+govern the Gilbert damping for the well-ordered phase in contrast to the
+damping of partially-ordered and disordered phases which is governed by
+interband electronic scattering alone. These results, especially the ultralow
+room temperature intrinsic damping observed for the well-ordered phase provide
+new fundamental insights to the physical origin of the Gilbert damping in full
+Heusler alloy thin films.",1706.04670v2
+2023-11-27,Gilbert damping in two-dimensional metallic anti-ferromagnets,"A finite spin life-time of conduction electrons may dominate Gilbert damping
+of two-dimensional metallic anti-ferromagnets or anti-ferromagnet/metal
+heterostructures. We investigate the Gilbert damping tensor for a typical
+low-energy model of a metallic anti-ferromagnet system with honeycomb magnetic
+lattice and Rashba spin-orbit coupling for conduction electrons. We distinguish
+three regimes of spin relaxation: exchange-dominated relaxation for weak
+spin-orbit coupling strength, Elliot-Yafet relaxation for moderate spin-orbit
+coupling, and Dyakonov-Perel relaxation for strong spin-orbit coupling. We
+show, however, that the latter regime takes place only for the in-plane Gilbert
+damping component. We also show that anisotropy of Gilbert damping persists for
+any finite spin-orbit interaction strength provided we consider no spatial
+variation of the N\'eel vector. Isotropic Gilbert damping is restored only if
+the electron spin-orbit length is larger than the magnon wavelength. Our theory
+applies to MnPS3 monolayer on Pt or to similar systems.",2311.16268v2
+2013-08-01,Inverse Spin Hall Effect in nanometer-thick YIG/Pt system,"High quality nanometer-thick (20 nm, 7 nm and 4 nm) epitaxial YIG films have
+been grown on GGG substrates using pulsed laser deposition. The Gilbert damping
+coefficient for the 20 nm thick films is 2.3 x 10-4 which is the lowest value
+reported for sub-micrometric thick films. We demonstrate Inverse spin Hall
+effect (ISHE) detection of propagating spin waves using Pt. The amplitude and
+the lineshape of the ISHE voltage correlate well to the increase of the Gilbert
+damping when decreasing thickness of YIG. Spin Hall effect based
+loss-compensation experiments have been conducted but no change in the
+magnetization dynamics could be detected.",1308.0192v1
+2020-08-14,Large enhancement of spin pumping due to the surface bound states in normal metal/superconductor structures,"We show that the spin pumping from ferromagnetic insulator into the adjacent
+metallic spin sink can be strongly stimulated by the superconducting
+correlations.
+  The key physical mechanism responsible for this effect is the presence of
+quasiparticle surface states at the ferromagnetic insulator/superconductor
+interface. We consider the minimal model when these states appear because of
+the suppressed pairing constant within the interfacial normal layer. For thin
+normal layers we obtain a strongly peaked temperature dependence of the Gilbert
+damping coefficient which has been recently observed in such systems. For
+thicker normal layers the Gilbert damping monotonically increases down to the
+temperatures much smaller than the critical one. The suggested model paves the
+way to controlling the temperature dependence of the spin pumping by
+fabricating hybrid normal metal/superconductor spin sinks.",2008.06253v1
+2012-07-28,Ultrafast optical control of magnetization in EuO thin films,"All-optical pump-probe detection of magnetization precession has been
+performed for ferromagnetic EuO thin films at 10 K. We demonstrate that the
+circularly-polarized light can be used to control the magnetization precession
+on an ultrafast time scale. This takes place within the 100 fs duration of a
+single laser pulse, through combined contribution from two nonthermal
+photomagnetic effects, i.e., enhancement of the magnetization and an inverse
+Faraday effect. From the magnetic field dependences of the frequency and the
+Gilbert damping parameter, the intrinsic Gilbert damping coefficient is
+evaluated to be {\alpha} \approx 3\times10^-3.",1207.6686v1
+2015-01-02,"Inertia, diffusion and dynamics of a driven skyrmion","Skyrmions recently discovered in chiral magnets are a promising candidate for
+magnetic storage devices because of their topological stability, small size
+($\sim 3-100$nm), and ultra-low threshold current density ($\sim
+10^{6}$A/m$^2$) to drive their motion. However, the time-dependent dynamics has
+hitherto been largely unexplored. Here we show, by combining the numerical
+solution of the Landau-Lifshitz-Gilbert equation and the analysis of a
+generalized Thiele's equation, that inertial effects are almost completely
+absent in skyrmion dynamics driven by a time-dependent current. In contrast,
+the response to time-dependent magnetic forces and thermal fluctuations depends
+strongly on frequency and is described by a large effective mass and a (anti-)
+damping depending on the acceleration of the skyrmion. Thermal diffusion is
+strongly suppressed by the cyclotron motion and is proportional to the Gilbert
+damping coefficient $\alpha$. This indicates that the skyrmion position is
+stable, and its motion responds to the time-dependent current without delay or
+retardation even if it is fast. These findings demonstrate the advantages of
+skyrmions as information carriers.",1501.00444v1
+2008-07-31,Scattering Theory of Gilbert Damping,"The magnetization dynamics of a single domain ferromagnet in contact with a
+thermal bath is studied by scattering theory. We recover the
+Landau-Liftshitz-Gilbert equation and express the effective fields and Gilbert
+damping tensor in terms of the scattering matrix. Dissipation of magnetic
+energy equals energy current pumped out of the system by the time-dependent
+magnetization, with separable spin-relaxation induced bulk and spin-pumping
+generated interface contributions. In linear response, our scattering theory
+for the Gilbert damping tensor is equivalent with the Kubo formalism.",0807.5009v1
+2016-04-11,All-Optical Study of Tunable Ultrafast Spin Dynamics in [Co/Pd]-NiFe Systems: The Role of Spin-Twist Structure on Gilbert Damping,"We investigate optically induced ultrafast magnetization dynamics in [Co(0.5
+nm)/Pd(1 nm)]x5/NiFe(t) exchange-spring samples with tilted perpendicular
+magnetic anisotropy using a time-resolved magneto-optical Kerr effect
+magnetometer. The competition between the out-of-plane anisotropy of the hard
+layer, the in-plane anisotropy of the soft layer and the applied bias field
+reorganizes the spins in the soft layer, which are modified further with the
+variation in t. The spin-wave spectrum, the ultrafast demagnetization time, and
+the extracted damping coefficient all depend on the spin distribution in the
+soft layer, while the latter two also depend on the spin-orbit coupling between
+the Co and Pd layers. The spin-wave spectra change from multimode to
+single-mode as t increases. At the maximum field reached in this study, H=2.5
+kOe, the damping shows a nonmonotonic dependence on t with a minimum at t=7.5
+nm. For t<7.5 nm, intrinsic effects dominate, whereas for t>7.5 nm, extrinsic
+effects govern the damping mechanisms.",1604.02998v1
+2024-01-18,Real-space nonlocal Gilbert damping from exchange torque correlation applied to bulk ferromagnets and their surfaces,"In this work we present an ab initio scheme based on linear response theory
+of exchange torque correlation, implemented into the real-space
+Korringa-Kohn-Rostoker (RS-KKR) framework to calculate diagonal elements of the
+atomic-site-dependent intrinsic Gilbert damping tensor. The method is first
+applied to bcc iron and fcc cobalt bulk systems. Beside reproducing earlier
+results from the literature for those bulk magnets, the effect of the lattice
+compression is also studied for Fe bulk, and significant changes for the
+Gilbert damping are found. Furthermore, (001)-oriented surfaces of Fe and Co
+are also investigated. It is found that the on-site Gilbert damping increases
+in the surface atomic layer and decreases in the subsurface layer, and
+approaches the bulk value moving further inside the magnets. Realistic atomic
+relaxation of the surface layers enhances the identified effects. The
+first-neighbor damping parameters are extremely sensitive to the surface
+relaxation. Despite their inhomogeneity caused by the surface, the transverse
+Gilbert damping tensor components remain largely insensitive to the
+magnetization direction.",2401.09938v2
+2007-06-12,Gilbert and Landau-Lifshitz damping in the presense of spin-torque,"A recent article by Stiles et al. (cond-mat/0702020) argued in favor of the
+Landau-Lifshitz damping term in the micromagnetic equations of motion over that
+of the more commonly accepted Gilbert damping form. Much of their argument
+revolved around spin-torque driven domain wall motion in narrow magnetic wires,
+since the presence of spin-torques can more acutely draw a distinction between
+the two forms of damping. In this article, the author uses simple arguments and
+examples to offer an alternative point of view favoring Gilbert.",0706.1736v1
+2015-06-02,Current-Driven Motion of Magnetic Domain Wall with Many Bloch Lines,"The current-driven motion of a domain wall (DW) in a ferromagnet with many
+Bloch lines (BLs) via the spin transfer torque is studied theoretically. It is
+found that the motion of BLs changes the current-velocity ($j$-$v$)
+characteristic dramatically. Especially, the critical current density to
+overcome the pinning force is reduced by the factor of the Gilbert damping
+coefficient $\alpha$ even compared with that of a skyrmion. This is in sharp
+contrast to the case of magnetic field driven motion, where the existence of
+BLs reduces the mobility of the DW.",1506.00723v1
+2023-03-13,Experimental investigation of the effect of topological insulator on the magnetization dynamics of ferromagnetic metal: $BiSbTe_{1.5}Se_{1.5}$ and $Ni_{80}Fe_{20}$ heterostructure,"We have studied ferromagnetic metal/topological insulator bilayer system to
+understand magnetization dynamics of ferromagnetic metal (FM) in contact with a
+topological insulator (TI). At magnetic resonance condition, the precessing
+magnetization in the metallic ferromagnet ($Ni_{80}Fe_{20}$) injects spin
+current into the topological insulator ($BiSbTe_{1.5}Se_{1.5}$), a phenomenon
+known as spin-pumping. Due to the spin pumping effect, fast relaxation in the
+ferromagnet results in the broadening of ferromagnetic resonance linewidth
+($\Delta H$). We evaluated the parameters like effective Gilbert damping
+coefficient ($\alpha_{eff}$), spin-mixing conductance ($g_{eff}^{\uparrow
+\downarrow}$) and spin current density ($j_S^0$) to confirm a successful spin
+injection due to spin-pumping into the $BiSbTe_{1.5}Se_{1.5}$ layer. TIs embody
+a spin-momentum locked surface state that span the bulk band-gap. It can act
+differently to the FM magnetization than the other normal metals. To probe the
+effect of topological surface state, a systematic low temperature study is
+crucial as surface state of TI dominates at lower temperatures. The exponential
+growth of $\Delta H$ for all different thickness combination of FM/TI bilayers
+and effective Gilbert damping coefficient ($\alpha_{eff}$) with lowering
+temperature confirms the prediction that spin chemical bias generated from
+spin-pumping induces surface current in TI due to spin-momentum locking. The
+hump-like feature of magnetic anisotropy field ($H_K$)of the bilayer around 60K
+suggests that the decrease of interfacial in-plane magnetic anisotropy can
+result from exchange coupling between the TI surface state and the local
+moments of FM layer.",2303.07025v2
+2021-01-07,Mechanisms behind large Gilbert damping anisotropies,"A method with which to calculate the Gilbert damping parameter from a
+real-space electronic structure method is reported here. The anisotropy of the
+Gilbert damping with respect to the magnetic moment direction and local
+chemical environment is calculated for bulk and surfaces of Fe$_{50}$Co$_{50}$
+alloys from first principles electronic structure in a real space formulation.
+The size of the damping anisotropy for Fe$_{50}$Co$_{50}$ alloys is
+demonstrated to be significant. Depending on details of the simulations, it
+reaches a maximum-minimum damping ratio as high as 200%. Several microscopic
+origins of the strongly enhanced Gilbert damping anisotropy have been examined,
+where in particular interface/surface effects stand out, as do local
+distortions of the crystal structure. Although theory does not reproduce the
+experimentally reported high ratio of 400% [Phys. Rev. Lett. 122, 117203
+(2019)], it nevertheless identifies microscopic mechanisms that can lead to
+huge damping anisotropies.",2101.02794v2
+2018-08-13,Gilbert damping phenomenology for two-sublattice magnets,"We present a systematic phenomenological description of Gilbert damping in
+two-sublattice magnets. Our theory covers the full range of materials from
+ferro- via ferri- to antiferromagnets. Following a Rayleigh dissipation
+functional approach within a Lagrangian classical field formulation, the theory
+captures intra- as well as cross-sublattice terms in the Gilbert damping,
+parameterized by a 2$\times$2 matrix. When spin-pumping into an adjacent
+conductor causes dissipation, we obtain the corresponding Gilbert damping
+matrix in terms of the interfacial spin-mixing conductances. Our model
+reproduces the experimentally observed enhancement of the ferromagnetic
+resonance linewidth in a ferrimagnet close to its compensation temperature
+without requiring an increased Gilbert parameter. It also predicts new
+contributions to damping in an antiferromagnet and suggests the resonance
+linewidths as a direct probe of the sublattice asymmetry, which may stem from
+boundary or bulk.",1808.04385v2
+2021-07-02,Anomalous Gilbert Damping and Duffing Features of the SFS {\boldmath $\varphi_0$} Josephson Junction,"We demonstrate unusual features of phase dynamics, IV-characteristics and
+magnetization dynamics of the $\varphi_0$ Josephson junction at small values of
+spin-orbit interaction, ratio of Josephson to magnetic energy and Gilbert
+damping. In particular, an anomalous shift of the ferromagnetic resonance
+frequency with an increase of Gilbert damping is found. The ferromagnetic
+resonance curves show the Duffing oscillator behaviour, reflecting the
+nonlinear nature of Landau-Lifshitz-Gilbert (LLG) equation. Based on the
+numerical analysis of each term in LLG equation we obtained an approximated
+equation demonstrated both damping effect and Duffing oscillator features. The
+resulting Duffing equation incorporates the Gilbert damping in a special way
+across the dissipative term and the restoring force. A resonance method for the
+determination of spin-orbit interaction in noncentrosymmetric materials which
+play the role of barrier in $\varphi_0$ junctions is proposed.",2107.00982v3
+2023-03-07,Electrically tunable Gilbert damping in van der Waals heterostructures of two-dimensional ferromagnetic metals and ferroelectrics,"Tuning the Gilbert damping of ferromagnetic (FM) metals via a nonvolatile way
+is of importance to exploit and design next-generation novel spintronic
+devices. Through systematical first-principles calculations, we study the
+magnetic properties of the van der Waals heterostructure of two-dimensional FM
+metal CrTe2 and ferroelectric (FE) In2Te3 monolayers. The ferromagnetism of
+CrTe2 is maintained in CrTe2/In2Te3 and its magnetic easy axis can be switched
+from in-plane to out-of-plane by reversing the FE polarization of In2Te3.
+Excitingly, we find that the Gilbert damping of CrTe2 is tunable when the FE
+polarization of In2Te3 is reversed from upward to downward. By analyzing the
+k-dependent contributions to the Gilbert damping, we unravel that such
+tunability results from the changed intersections between the bands of CrTe2
+and Fermi level on the reversal of the FE polarizations of In2Te3 in
+CrTe2/In2Te3. Our work provides an appealing way to electrically tailor Gilbert
+dampings of two-dimensional FM metals by contacting them with ferroelectrics.",2303.03852v1
+2015-08-28,The inviscid limit for the Landau-Lifshitz-Gilbert equation in the critical Besov space,"We prove that in dimensions three and higher the Landau-Lifshitz- Gilbert
+equation with small initial data in the critical Besov space is globally
+wellposed in a uniform way with respect to the Gilbert damping parameter. Then
+we show that the global solution converges to that of the Schrodinger maps in
+the natural space as the Gilbert damping term vanishes. The proof is based on
+some studies on the derivative Ginzburg-Landau equations.",1508.07118v3
+2023-09-20,Evaluating Gilbert Damping in Magnetic Insulators from First Principles,"Magnetic damping has a significant impact on the performance of various
+magnetic and spintronic devices, making it a long-standing focus of research.
+The strength of magnetic damping is usually quantified by the Gilbert damping
+constant in the Landau-Lifshitz-Gilbert equation. Here we propose a
+first-principles based approach to evaluate the Gilbert damping constant
+contributed by spin-lattice coupling in magnetic insulators. The approach
+involves effective Hamiltonian models and spin-lattice dynamics simulations. As
+a case study, we applied our method to Y$_3$Fe$_5$O$_{12}$, MnFe$_2$O$_4$ and
+Cr$_2$O$_3$. Their damping constants were calculated to be $0.8\times10^{-4}$,
+$0.2\times10^{-4}$, $2.2\times 10^{-4}$, respectively at a low temperature. The
+results for Y$_3$Fe$_5$O$_{12}$ and Cr$_2$O$_3$ are in good agreement with
+experimental measurements, while the discrepancy in MnFe$_2$O$_4$ can be
+attributed to the inhomogeneity and small band gap in real samples. The
+stronger damping observed in Cr$_2$O$_3$, compared to Y$_3$Fe$_5$O$_{12}$,
+essentially results from its stronger spin-lattice coupling. In addition, we
+confirmed a proportional relationship between damping constants and the
+temperature difference of subsystems, which had been reported in previous
+studies. These successful applications suggest that our approach serves as a
+promising candidate for estimating the Gilbert damping constant in magnetic
+insulators.",2309.11152v1
+2008-11-25,The quantum-mechanical basis of an extended Landau-Lifshitz-Gilbert equation for a current-carrying ferromagnetic wire,"An extended Landau-Lifshitz-Gilbert (LLG) equation is introduced to describe
+the dynamics of inhomogeneous magnetization in a current-carrying wire. The
+coefficients of all the terms in this equation are calculated
+quantum-mechanically for a simple model which includes impurity scattering.
+This is done by comparing the energies and lifetimes of a spin wave calculated
+from the LLG equation and from the explicit model. Two terms are of particular
+importance since they describe non-adiabatic spin-transfer torque and damping
+processes which do not rely on spin-orbit coupling. It is shown that these
+terms may have a significant influence on the velocity of a current-driven
+domain wall and they become dominant in the case of a narrow wall.",0811.4118v1
+2019-06-25,Conductivity-Like Gilbert Damping due to Intraband Scattering in Epitaxial Iron,"Confirming the origin of Gilbert damping by experiment has remained a
+challenge for many decades, even for simple ferromagnetic metals. In this
+Letter, we experimentally identify Gilbert damping that increases with
+decreasing electronic scattering in epitaxial thin films of pure Fe. This
+observation of conductivity-like damping, which cannot be accounted for by
+classical eddy current loss, is in excellent quantitative agreement with
+theoretical predictions of Gilbert damping due to intraband scattering. Our
+results resolve the longstanding question about a fundamental damping mechanism
+and offer hints for engineering low-loss magnetic metals for cryogenic
+spintronics and quantum devices.",1906.10326v2
+2008-08-28,Gilbert Damping in Conducting Ferromagnets II: Model Tests of the Torque-Correlation Formula,"We report on a study of Gilbert damping due to particle-hole pair excitations
+in conducting ferromagnets. We focus on a toy two-band model and on a four-band
+spherical model which provides an approximate description of ferromagnetic
+(Ga,Mn)As. These models are sufficiently simple that disorder-ladder-sum vertex
+corrections to the long-wavelength spin-spin response function can be summed to
+all orders. An important objective of this study is to assess the reliability
+of practical approximate expressions which can be combined with electronic
+structure calculations to estimate Gilbert damping in more complex systems.",0808.3923v1
+2010-01-26,Effect of spin-conserving scattering on Gilbert damping in ferromagnetic semiconductors,"The Gilbert damping in ferromagnetic semiconductors is theoretically
+investigated based on the $s$-$d$ model. In contrast to the situation in
+metals, all the spin-conserving scattering in ferromagnetic semiconductors
+supplies an additional spin relaxation channel due to the momentum dependent
+effective magnetic field of the spin-orbit coupling, thereby modifies the
+Gilbert damping. In the presence of a pure spin current, we predict a new
+contribution due to the interplay of the anisotropic spin-orbit coupling and a
+pure spin current.",1001.4576v1
+2011-05-20,"Magnetization Dissipation in the Ferromagnetic Semiconductor (Ga,Mn)As","We compute the Gilbert damping in (Ga,Mn)As based on the scattering theory of
+magnetization relaxation. The disorder scattering is included
+non-perturbatively. In the clean limit, the spin-pumping from the localized
+d-electrons to the itinerant holes dominates the relaxation processes. In the
+diffusive regime, the breathing Fermi-surface effect is balanced by the effects
+of interband scattering, which cause the Gilbert damping constant to saturate
+at around 0.005. In small samples, the system shape induces a large anisotropy
+in the Gilbert damping.",1105.4148v2
+2008-12-17,Origin of intrinsic Gilbert damping,"The damping of magnetization, represented by the rate at which it relaxes to
+equilibrium, is successfully modeled as a phenomenological extension in the
+Landau-Lifschitz-Gilbert equation. This is the damping torque term known as
+Gilbert damping and its direction is given by the vector product of the
+magnetization and its time derivative. Here we derive the Gilbert term from
+first principles by a non-relativistic expansion of the Dirac equation. We find
+that the Gilbert term arises when one calculates the time evolution of the spin
+observable in the presence of the full spin-orbital coupling terms, while
+recognizing the relationship between the curl of the electric field and the
+time varying magnetic induction.",0812.3184v2
+2019-07-01,Magnon decay theory of Gilbert damping in metallic antiferromagnets,"Gilbert damping is a key property governing magnetization dynamics in ordered
+magnets. We present a theoretical study of intrinsic Gilbert damping induced by
+magnon decay in antiferromagnetic metals through $s$-$d$ exchange interaction.
+Our theory delineates the qualitative features of damping in metallic
+antiferromagnets owing to their bipartite nature, in addition to providing
+analytic expressions for the damping parameters. Magnon-induced intraband
+electron scattering is found to predominantly cause magnetization damping,
+whereas the N\'eel field is found to be damped via disorder. Depending on the
+conduction electron band structure, we predict that magnon-induced interband
+electron scattering around band crossings may be exploited to engineer a strong
+N\'eel field damping.",1907.01045v1
+2022-11-24,Influence of non-local damping on magnon properties of ferromagnets,"We study the influence of non-local damping on magnon properties of Fe, Co,
+Ni and Fe$_{1-x}$Co$_{x}$ ($x=30\%,50\%$) alloys. The Gilbert damping parameter
+is typically considered as a local scalar both in experiment and in theoretical
+modelling. However, recent works have revealed that Gilbert damping is a
+non-local quantity that allows for energy dissipation between atomic sites.
+With the Gilbert damping parameters calculated from a state-of-the-art
+real-space electronic structure method, magnon lifetimes are evaluated from
+spin dynamics and linear response, where a good agreement is found between
+these two methods. It is found that non-local damping affects the magnon
+lifetimes in different ways depending on the system. Specifically, we find that
+in Fe, Co, and Ni the non-local damping decreases the magnon lifetimes, while
+in $\rm Fe_{70}Co_{30}$ and Fe$_{50}$Co$_{50}$ an opposite, non-local damping
+effect is observed, and our data show that it is much stronger in the former.",2211.13486v1
+2010-02-26,Correlation Effects in the Stochastic Landau-Lifshitz-Gilbert Equation,"We analyze the Landau-Lifshitz-Gilbert equation when the precession motion of
+the magnetic moments is additionally subjected to an uniaxial anisotropy and is
+driven by a multiplicative coupled stochastic field with a finite correlation
+time $\tau$. The mean value for the spin wave components offers that the
+spin-wave dispersion relation and its damping is strongly influenced by the
+deterministic Gilbert damping parameter $\alpha$, the strength of the
+stochastic forces $D$ and its temporal range $\tau$. The spin-spin-correlation
+function can be calculated in the low correlation time limit by deriving an
+evolution equation for the joint probability function. The stability analysis
+enables us to find the phase diagram within the $\alpha-D$ plane for different
+values of $\tau$ where damped spin wave solutions are stable. Even for zero
+deterministic Gilbert damping the magnons offer a finite lifetime. We detect a
+parameter range where the deterministic and the stochastic damping mechanism
+are able to compensate each other leading to undamped spin-waves. The onset is
+characterized by a critical value of the correlation time. An enhancement of
+$\tau$ leads to an increase of the oscillations of the correlation function.",1002.4958v1
+2019-02-26,Enhanced Gilbert Damping in Re doped FeCo Films: A Combined Experimental and Theoretical Study,"The effects of rhenium doping in the range 0 to 10 atomic percent on the
+static and dynamic magnetic properties of Fe65Co35 thin films have been studied
+experimentally as well as with first principles electronic structure
+calculations focusing on the change of the saturation magnetization and the
+Gilbert damping parameter. Both experimental and theoretical results show that
+the saturation magnetization decreases with increasing Re doping level, while
+at the same time Gilbert damping parameter increases. The experimental low
+temperature saturation magnetic induction exhibits a 29 percent decrease, from
+2.31 T to 1.64 T, in the investigated doping concentration range, which is more
+than predicted by the theoretical calculations. The room temperature value of
+the damping parameter obtained from ferromagnetic resonance measurements,
+correcting for extrinsic contributions to the damping, is for the undoped
+sample 0.0027, which is close to the theoretically calculated Gilbert damping
+parameter. With 10 atomic percent Re doping, the damping parameter increases to
+0.0090, which is in good agreement with the theoretical value of 0.0073. The
+increase in damping parameter with Re doping is explained by the increase in
+density of states at Fermi level, mostly contributed by the spin-up channel of
+Re. Moreover, both experimental and theoretical values for the damping
+parameter are observed to be weakly decreasing with decreasing temperature.",1902.09896v1
+2018-12-18,Thermal gradient driven domain wall dynamics,"The issue of whether a thermal gradient acts like a magnetic field or an
+electric current in the domain wall (DW) dynamics is investigated. Broadly
+speaking, magnetization control knobs can be classified as energy-driving or
+angular-momentum driving forces. DW propagation driven by a static magnetic
+field is the best-known example of the former in which the DW speed is
+proportional to the energy dissipation rate, and the current-driven DW motion
+is an example of the latter. Here we show that DW propagation speed driven by a
+thermal gradient can be fully explained as the angular momentum transfer
+between thermally generated spin current and DW. We found DW-plane rotation
+speed increases as DW width decreases. Both DW propagation speed along the wire
+and DW-plane rotation speed around the wire decrease with the Gilbert damping.
+These facts are consistent with the angular momentum transfer mechanism, but
+are distinct from the energy dissipation mechanism. We further show that
+magnonic spin-transfer torque (STT) generated by a thermal gradient has both
+damping-like and field-like components. By analyzing DW propagation speed and
+DW-plane rotation speed, the coefficient ( \b{eta}) of the field-like STT
+arising from the non-adiabatic process, is obtained. It is found that \b{eta}
+does not depend on the thermal gradient; increases with uniaxial anisotropy
+K_(||) (thinner DW); and decreases with the damping, in agreement with the
+physical picture that a larger damping or a thicker DW leads to a better
+alignment between the spin-current polarization and the local magnetization, or
+a better adiabaticity.",1812.07244v2
+2023-06-07,Helicity-dependent optical control of the magnetization state emerging from the Landau-Lifshitz-Gilbert equation,"It is well known that the Gilbert relaxation time of a magnetic moment scales
+inversely with the magnitude of the externally applied field, H, and the
+Gilbert damping, {\alpha}. Therefore, in ultrashort optical pulses, where H can
+temporarily be extremely large, the Gilbert relaxation time can momentarily be
+extremely short, reaching even picosecond timescales. Here we show that for
+typical ultrashort pulses, the optical control of the magnetization emerges by
+merely considering the optical magnetic field in the Landau-Lifshitz-Gilbert
+(LLG) equation. Surprisingly, when circularly polarized optical pulses are
+introduced to the LLG equation, an optically induced helicity-dependent torque
+results. We find that the strength of the interaction is determined by
+{\eta}={\alpha}{\gamma}H/f_opt, where f_opt and {\gamma} are the optical
+frequency and gyromagnetic ratio. Our results illustrate the generality of the
+LLG equation to the optical limit and the pivotal role of the Gilbert damping
+in the general interaction between optical magnetic fields and spins in solids.",2306.04617v2
+2018-04-03,Generalisation of Gilbert damping and magnetic inertia parameter as a series of higher-order relativistic terms,"The phenomenological Landau-Lifshitz-Gilbert (LLG) equation of motion remains
+as the cornerstone of contemporary magnetisation dynamics studies, wherein the
+Gilbert damping parameter has been attributed to first-order relativistic
+effects. To include magnetic inertial effects the LLG equation has previously
+been extended with a supplemental inertia term and the arising inertial
+dynamics has been related to second-order relativistic effects. Here we start
+from the relativistic Dirac equation and, performing a Foldy-Wouthuysen
+transformation, derive a generalised Pauli spin Hamiltonian that contains
+relativistic correction terms to any higher order. Using the Heisenberg
+equation of spin motion we derive general relativistic expressions for the
+tensorial Gilbert damping and magnetic inertia parameters, and show that these
+tensors can be expressed as series of higher-order relativistic correction
+terms. We further show that, in the case of a harmonic external driving field,
+these series can be summed and we provide closed analytical expressions for the
+Gilbert and inertial parameters that are functions of the frequency of the
+driving field.",1804.09242v1
+2016-08-02,Ferromagnetic Damping/Anti-damping in a Periodic 2D Helical surface; A Non-Equilibrium Keldysh Green Function Approach,"In this paper, we investigate theoretically the spin-orbit torque as well as
+the Gilbert damping for a two band model of a 2D helical surface state with a
+Ferromagnetic (FM) exchange coupling. We decompose the density matrix into the
+Fermi sea and Fermi surface components and obtain their contributions to the
+electronic transport as well as the spin-orbit torque (SOT). Furthermore, we
+obtain the expression for the Gilbert damping due to the surface state of a 3D
+Topological Insulator (TI) and predicted its dependence on the direction of the
+magnetization precession axis.",1608.00984v2
+2016-02-19,A systematic study of magnetodynamic properties at finite temperatures in doped permalloy from first principles calculations,"By means of first principles calculations, we have systematically
+investigated how the magnetodynamic properties Gilbert damping, magnetization
+and exchange stiffness are affected when permalloy (Py)
+(Fe$_{0.19}$Ni$_{0.81}$) is doped with 4d or 5d transition metal impurities. We
+find that the trends in the Gilbert damping can be understood from relatively
+few basic parameters such as the density of states at the Fermi level, the
+spin-orbit coupling and the impurity concentration. % The temperature
+dependence of the Gilbert damping is found to be very weak which we relate to
+the lack of intraband transitions in alloys. % Doping with $4d$ elements has no
+major impact on the studied Gilbert damping, apart from diluting the host.
+However, the $5d$ elements have a profound effect on the damping and allows it
+to be tuned over a large interval while maintaining the magnetization and
+exchange stiffness. % As regards spin stiffness, doping with early transition
+metals results in considerable softening, whereas late transition metals have a
+minor impact. % Our result agree well with earlier calculations where
+available. In comparison to experiments, the computed Gilbert damping appears
+slightly underestimated while the spin stiffness show good general agreement.",1602.06201v2
+2002-11-01,Exploring dynamical magnetism with time-dependent density-functional theory: from spin fluctuations to Gilbert damping,"We use time-dependent spin-density-functional theory to study dynamical
+magnetic phenomena. First, we recall that the local-spin-density approximation
+(LSDA) fails to account correctly for magnetic fluctuations in the paramagnetic
+state of iron and other itinerant ferromagnets. Next, we construct a
+gradient-dependent density functional that does not suffer from this problem of
+the LSDA. This functional is then used to derive, for the first time, the
+phenomenological Gilbert equation of micromagnetics directly from
+time-dependent density-functional theory. Limitations and extensions of Gilbert
+damping are discussed on this basis, and some comparisons with phenomenological
+theories and experiments are made.",0211021v1
+2012-04-24,Nonlocal feedback in ferromagnetic resonance,"Ferromagnetic resonance in thin films is analyzed under the influence of
+spatiotemporal feedback effects. The equation of motion for the magnetization
+dynamics is nonlocal in both space and time and includes isotropic, anisotropic
+and dipolar energy contributions as well as the conserved Gilbert- and the
+non-conserved Bloch-damping. We derive an analytical expression for the
+peak-to-peak linewidth. It consists of four separate parts originated by
+Gilbert damping, Bloch-damping, a mixed Gilbert-Bloch component and a
+contribution arising from retardation. In an intermediate frequency regime the
+results are comparable with the commonly used Landau-Lifshitz-Gilbert theory
+combined with two-magnon processes. Retardation effects together with Gilbert
+damping lead to a linewidth the frequency dependence of which becomes strongly
+nonlinear. The relevance and the applicability of our approach to ferromagnetic
+resonance experiments is discussed.",1204.5342v1
+2017-04-24,Spin injection into silicon detected by broadband ferromagnetic resonance spectroscopy,"We studied the spin injection in a NiFe(Py)/Si system using broadband
+ferromagnetic resonance spectroscopy. The Gilbert damping parameter of the Py
+layer on top of the Si channel was determined as a function of the Si doping
+concentration and Py layer thickness. For fixed Py thickness we observed an
+increase of the Gilbert damping parameter with decreasing resistivity of the Si
+channel. For a fixed Si doping concentration we measured an increasing Gilbert
+damping parameter for decreasing Py layer thickness. No increase of the Gilbert
+damping parameter was found Py/Si samples with an insulating interlayer. We
+attribute our observations to an enhanced spin injection into the
+low-resistivity Si by spin pumping.",1704.07006v1
+2019-11-07,Quantum Oscillations of Gilbert Damping in Ferromagnetic/Graphene Bilayer Systems,"We study the spin dynamics of a ferromagnetic insulator on which graphene is
+placed. We show that the Gilbert damping is enhanced by the proximity exchange
+coupling at the interface. The modulation of the Gilbert damping constant is
+proportional to the product of the spin-up and spin-down densities of states of
+graphene. Consequently, the Gilbert damping constant in a strong magnetic field
+oscillates as a function of the external magnetic field that originates from
+the Landau level structure of graphene. We find that a measurement of the
+oscillation period enables the strength of the exchange coupling constant to be
+determined. The results demonstrate in theory that the ferromagnetic resonance
+measurements may be used to detect the spin resolved electronic structure of
+the adjacent materials, which is critically important for future spin device
+evaluations.",1911.02775v2
+2021-03-11,Magnetoelastic Gilbert damping in magnetostrictive Fe$_{0.7}$Ga$_{0.3}$ thin films,"We report an enhanced magnetoelastic contribution to the Gilbert damping in
+highly magnetostrictive Fe$_{0.7}$Ga$_{0.3}$ thin films. This effect is
+mitigated for perpendicular-to-plane fields, leading to a large anisotropy of
+the Gilbert damping in all of the films (up to a factor of 10 at room
+temperature). These claims are supported by broadband measurements of the
+ferromagnetic resonance linewidths over a range of temperatures (5 to 400 K),
+which serve to elucidate the effect of both the magnetostriction and phonon
+relaxation on the magnetoelastic Gilbert damping.",2103.07008v1
+2022-01-27,Effect of vertex corrections on the enhancement of Gilbert damping in spin pumping into a two-dimensional electron gas,"We theoretically consider the effect of vertex correction on spin pumping
+from a ferromagnetic insulator (FI) into a two-dimensional electron gas (2DEG)
+in which the Rashba and Dresselhaus spin-orbit interactions coexist. The
+Gilbert damping in the FI is enhanced by elastic spin-flipping or magnon
+absorption. We show that the Gilbert damping due to elastic spin-flipping is
+strongly enhanced by the vertex correction when the ratio of the two spin-orbit
+interactions is near a special value at which the spin relaxation time diverges
+while that due to magnon absorption shows only small modification. We also show
+that the shift in the resonant frequency due to elastic spin-flipping is
+strongly enhanced in a similar way as the Gilbert damping.",2201.11498v3
+2016-02-22,Effects of Landau-Lifshitz-Gilbert damping on domain growth,"Domain patterns are simulated by the Landau-Lifshitz-Gilbert (LLG) equation
+with an easy-axis anisotropy. If the Gilbert damping is removed from the LLG
+equation, it merely describes the precession of magnetization with a
+ferromagnetic interaction. However, even without the damping, domains that look
+similar to those of scalar fields are formed, and they grow with time. It is
+demonstrated that the damping has no significant effects on domain growth laws
+and large-scale domain structure. In contrast, small-scale domain structure is
+affected by the damping. The difference in small-scale structure arises from
+energy dissipation due to the damping.",1602.06673v3
+2018-06-13,Low magnetic damping of ferrimagnetic GdFeCo alloys,"We investigate the Gilbert damping parameter for rare earth (RE)-transition
+metal (TM) ferrimagnets over a wide temperature range. Extracted from the
+field-driven magnetic domain-wall mobility, the Gilbert damping parameter was
+as low as 0.0072 and was almost constant across the angular momentum
+compensation temperature, starkly contrasting previous predictions that the
+Gilbert damping parameter should diverge at the angular momentum compensation
+temperature due to vanishing total angular momentum. Thus, magnetic damping of
+RE-TM ferrimagnets is not related to the total angular momentum but is
+dominated by electron scattering at the Fermi level where the TM has a dominant
+damping role.",1806.04881v1
+2023-06-22,"Gilbert damping in metallic ferromagnets from Schwinger-Keldysh field theory: Intrinsically nonlocal and nonuniform, and made anisotropic by spin-orbit coupling","Understanding the origin of damping mechanisms in magnetization dynamics of
+metallic ferromagnets is a fundamental problem for nonequilibrium many-body
+physics of systems where quantum conduction electrons interact with localized
+spins assumed to be governed by the classical Landau-Lifshitz-Gilbert (LLG)
+equation. It is also of critical importance for applications, as damping
+affects energy consumption and speed of spintronic and magnonic devices. Since
+the 1970s, a variety of linear-response and scattering theory approaches have
+been developed to produce widely used formulas for computation of
+spatially-independent Gilbert scalar parameter as the magnitude of the Gilbert
+damping term in the LLG equation. The largely unexploited for this purpose
+Schwinger-Keldysh field theory (SKFT) offers additional possibilities, such as
+to rigorously derive an extended LLG equation by integrating quantum electrons
+out. Here we derive such equation whose Gilbert damping for metallic
+ferromagnets is nonlocal, i.e., dependent on all localized spins at a given
+time, and nonuniform, even if all localized spins are collinear and spin-orbit
+coupling (SOC) is absent. This is in sharp contrast to standard lore, where
+nonlocal damping is considered to emerge only if localized spins are
+noncollinear; for such situations, direct comparison on the example of magnetic
+domain wall shows that SKFT-derived nonlocal damping is an order of magnitude
+larger than the previously considered one. Switching on SOC makes such nonlocal
+damping anisotropic, in contrast to standard lore where SOC is usually
+necessary to obtain nonzero Gilbert damping scalar parameter. Our analytical
+formulas, with their nonlocality being more prominent in low spatial
+dimensions, are fully corroborated by numerically exact quantum-classical
+simulations.",2306.13013v4
+2018-07-20,Another view on Gilbert damping in two-dimensional ferromagnets,"A keen interest towards technological implications of spin-orbit driven
+magnetization dynamics requests a proper theoretical description, especially in
+the context of a microscopic framework, to be developed. Indeed, magnetization
+dynamics is so far approached within Landau-Lifshitz-Gilbert equation which
+characterizes torques on magnetization on purely phenomenological grounds.
+Particularly, spin-orbit coupling does not respect spin conservation, leading
+thus to angular momentum transfer to lattice and damping as a result. This
+mechanism is accounted by the Gilbert damping torque which describes relaxation
+of the magnetization to equilibrium. In this study we work out a microscopic
+Kubo-St\v{r}eda formula for the components of the Gilbert damping tensor and
+apply the elaborated formalism to a two-dimensional Rashba ferromagnet in the
+weak disorder limit. We show that an exact analytical expression corresponding
+to the Gilbert damping parameter manifests linear dependence on the scattering
+rate and retains the constant value up to room temperature when no vibrational
+degrees of freedom are present in the system. We argue that the methodology
+developed in this paper can be safely applied to bilayers made of non- and
+ferromagnetic metals, e.g., CoPt.",1807.07897v2
+2008-06-28,Theory of spin magnetohydrodynamics,"We develop a phenomenological hydrodynamic theory of coherent magnetic
+precession coupled to electric currents. Exchange interaction between electron
+spin and collective magnetic texture produces two reciprocal effects:
+spin-transfer torque on the magnetic order parameter and the Berry-phase gauge
+field experienced by the itinerant electrons. The dissipative processes are
+governed by three coefficients: the ohmic resistance, Gilbert damping of the
+magnetization, and the ""beta coefficient"" describing viscous coupling between
+magnetic dynamics and electric current, which stems from spin mistracking of
+the magnetic order. We develop general magnetohydrodynamic equations and
+discuss the net dissipation produced by the coupled dynamics. The latter in
+particular allows us to determine a lower bound on the magnetic-texture
+resistivity.",0806.4656v2
+2008-11-13,"Intrinsic Coupling between Current and Domain Wall Motion in (Ga,Mn)As","We consider current-induced domain wall motion and, the reciprocal process,
+moving domain wall-induced current. The associated Onsager coefficients are
+expressed in terms of scattering matrices. Uncommonly, in (Ga,Mn)As, the
+effective Gilbert damping coefficient $\alpha_w$ and the effective out-of-plane
+spin transfer torque parameter $\beta_w$ are dominated by spin-orbit
+interaction in combination with scattering off the domain wall, and not
+scattering off extrinsic impurities. Numerical calculations give $\alpha_w \sim
+0.01$ and $\beta_w \sim 1$ in dirty (Ga,Mn)As. The extraordinary large
+$\beta_w$ parameter allows experimental detection of current or voltage induced
+by domain wall motion in (Ga,Mn)As.",0811.2235v2
+2009-05-01,Spin excitations in a monolayer scanned by a magnetic tip,"Energy dissipation via spin excitations is investigated for a hard
+ferromagnetic tip scanning a soft magnetic monolayer. We use the classical
+Heisenberg model with Landau-Lifshitz-Gilbert (LLG)-dynamics including a
+stochastic field representing finite temperatures. The friction force depends
+linearly on the velocity (provided it is small enough) for all temperatures.
+For low temperatures, the corresponding friction coefficient is proportional to
+the phenomenological damping constant of the LLG equation. This dependence is
+lost at high temperatures, where the friction coefficient decreases
+exponentially. These findings can be explained by properties of the spin
+polarization cloud dragged along with the tip.",0905.0112v2
+2016-05-21,Landau-Lifshitz theory of the magnon-drag thermopower,"Metallic ferromagnets subjected to a temperature gradient exhibit a magnonic
+drag of the electric current. We address this problem by solving a stochastic
+Landau-Lifshitz equation to calculate the magnon-drag thermopower. The
+long-wavelength magnetic dynamics result in two contributions to the
+electromotive force acting on electrons: (1) An adiabatic Berry-phase force
+related to the solid angle subtended by the magnetic precession and (2) a
+dissipative correction thereof, which is rooted microscopically in the
+spin-dephasing scattering. The first contribution results in a net force
+pushing the electrons towards the hot side, while the second contribution drags
+electrons towards the cold side, i.e., in the direction of the magnonic drift.
+The ratio between the two forces is proportional to the ratio between the
+Gilbert damping coefficient $\alpha$ and the coefficient $\beta$ parametrizing
+the dissipative contribution to the electromotive force.",1605.06578v1
+2019-06-17,Controlling acoustic waves using magnetoelastic Fano resonances,"We propose and analyze theoretically a class of energy-efficient
+magneto-elastic devices for analogue signal processing. The signals are carried
+by transverse acoustic waves while the bias magnetic field controls their
+scattering from a magneto-elastic slab. By tuning the bias field, one can alter
+the resonant frequency at which the propagating acoustic waves hybridize with
+the magnetic modes, and thereby control transmission and reflection
+coefficients of the acoustic waves. The scattering coefficients exhibit
+Breit-Wigner/Fano resonant behaviour akin to inelastic scattering in atomic and
+nuclear physics. Employing oblique incidence geometry, one can effectively
+enhance the strength of magnetoelastic coupling, and thus countermand the
+magnetic losses due to the Gilbert damping. We apply our theory to discuss
+potential benefits and issues in realistic systems and suggest further routes
+to enhance performance of the proposed devices.",1906.07297v2
+2017-05-21,Dynamical depinning of chiral domain walls,"The domain wall depinning field represents the minimum magnetic field needed
+to move a domain wall, typically pinned by samples' disorder or patterned
+constrictions. Conventionally, such field is considered independent on the
+Gilbert damping since it is assumed to be the field at which the Zeeman energy
+equals the pinning energy barrier (both damping independent). Here, we analyse
+numerically the domain wall depinning field as function of the Gilbert damping
+in a system with perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya
+interaction. Contrary to expectations, we find that the depinning field depends
+on the Gilbert damping and that it strongly decreases for small damping
+parameters. We explain this dependence with a simple one-dimensional model and
+we show that the reduction of the depinning field is related to the internal
+domain wall dynamics, proportional to the Dzyaloshinskii-Moriya interaction,
+and the finite size of the pinning barriers.",1705.07489v2
+2019-01-07,Giant anisotropy of Gilbert damping in epitaxial CoFe films,"Tailoring Gilbert damping of metallic ferromagnetic thin films is one of the
+central interests in spintronics applications. Here we report a giant Gilbert
+damping anisotropy in epitaxial Co$_{50}$Fe$_{50}$ thin film with a
+maximum-minimum damping ratio of 400 \%, determined by broadband spin-torque as
+well as inductive ferromagnetic resonance. We conclude that the origin of this
+damping anisotropy is the variation of the spin orbit coupling for different
+magnetization orientations in the cubic lattice, which is further corroborate
+from the magnitude of the anisotropic magnetoresistance in Co$_{50}$Fe$_{50}$.",1901.01941v1
+2019-11-02,Tuning Non-Gilbert-type damping in FeGa films on MgO(001) via oblique deposition,"The ability to tailor the damping factor is essential for spintronic and
+spin-torque applications. Here, we report an approach to manipulate the damping
+factor of FeGa/MgO(001) films by oblique deposition. Owing to the defects at
+the surface or interface in thin films, two-magnon scattering (TMS) acts as a
+non-Gilbert damping mechanism in magnetization relaxation. In this work, the
+contribution of TMS was characterized by in-plane angular dependent
+ferromagnetic resonance (FMR). It is demonstrated that the intrinsic Gilbert
+damping is isotropic and invariant, while the extrinsic mechanism related to
+TMS is anisotropic and can be tuned by oblique deposition. Furthermore, the two
+and fourfold TMS related to the uniaxial magnetic anisotropy (UMA) and
+magnetocrystalline anisotropy were discussed. Our results open an avenue to
+manipulate magnetization relaxation in spintronic devices.",1911.00728v1
+2001-10-11,Enhanced Gilbert Damping in Thin Ferromagnetic Films,"Using a scattering matrix approach, the precession of the magnetization of a
+ferromagnet is shown to transfer spins into adjacent normal metal layers. This
+``pumping'' of spins slows down the precession corresponding to an enhanced
+Gilbert damping factor in the Landau-Lifshitz equation. The damping is
+expressed in terms of the scattering matrix of the ferromagnet-normal metal
+interface, which is accessible to model and first-principles calculations. Our
+estimates for permalloy thin films explain the trends observed in recent
+experiments.",0110247v2
+2006-01-10,Voltage dependence of Landau-Lifshitz-Gilbert damping of a spin in a current driven tunnel junction,"We present a theory of Landau-Lifshitz-Gilbert damping $\alpha$ for a
+localized spin ${\vec S}$ in the junction coupled to the conduction electrons
+in both leads under an applied volatege $V$. We find the voltage dependence of
+the damping term reflecting the energy dependence of the density of states. We
+find the effect is linear in the voltage and cotrolled by particle-hole
+asymmetry of the leads.",0601185v1
+2015-02-06,Microscopic theory of Gilbert damping in metallic ferromagnets,"We present a microscopic theory for magnetization relaxation in metallic
+ferromagnets of nanoscopic dimensions that is based on the dynamic spin
+response matrix in the presence of spin-orbit coupling. Our approach allows the
+calculation of the spin excitation damping rate even for perfectly crystalline
+systems, where existing microscopic approaches fail. We demonstrate that the
+relaxation properties are not completely determined by the transverse
+susceptibility alone, and that the damping rate has a non-negligible frequency
+dependence in experimentally relevant situations. Our results indicate that the
+standard Landau-Lifshitz-Gilbert phenomenology is not always appropriate to
+describe spin dynamics of metallic nanostructure in the presence of strong
+spin-orbit coupling.",1502.02068v1
+2018-05-03,"Exact Intrinsic Localized Excitation of an Anisotropic Ferromagnetic Spin Chain in External Magnetic Field with Gilbert Damping, Spin Current and PT-Symmetry","We obtain the exact one-spin intrinsic localized excitation in an anisotropic
+Heisenberg ferromagnetic spin chain in a constant/variable external magnetic
+field with Gilbert damping included. We also point out how an appropriate
+magnitude spin current term in a spin transfer nano-oscillator (STNO) can
+stabilize the tendency towards damping. Further, we show how this excitation
+can be sustained in a recently suggested PT-symmetric magnetic nanostructure.
+We also briefly consider more general spin excitations.",1805.01230v1
+2011-04-08,Magnetization Dissipation in Ferromagnets from Scattering Theory,"The magnetization dynamics of ferromagnets are often formulated in terms of
+the Landau-Lifshitz-Gilbert (LLG) equation. The reactive part of this equation
+describes the response of the magnetization in terms of effective fields,
+whereas the dissipative part is parameterized by the Gilbert damping tensor. We
+formulate a scattering theory for the magnetization dynamics and map this
+description on the linearized LLG equation by attaching electric contacts to
+the ferromagnet. The reactive part can then be expressed in terms of the static
+scattering matrix. The dissipative contribution to the low-frequency
+magnetization dynamics can be described as an adiabatic energy pumping process
+to the electronic subsystem by the time-dependent magnetization. The Gilbert
+damping tensor depends on the time derivative of the scattering matrix as a
+function of the magnetization direction. By the fluctuation-dissipation
+theorem, the fluctuations of the effective fields can also be formulated in
+terms of the quasistatic scattering matrix. The theory is formulated for
+general magnetization textures and worked out for monodomain precessions and
+domain wall motions. We prove that the Gilbert damping from scattering theory
+is identical to the result obtained by the Kubo formalism.",1104.1625v1
+2022-02-12,Generalization of the Landau-Lifshitz-Gilbert equation by multi-body contributions to Gilbert damping for non-collinear magnets,"We propose a systematic and sequential expansion of the
+Landau-Lifshitz-Gilbert equation utilizing the dependence of the Gilbert
+damping tensor on the angle between magnetic moments, which arises from
+multi-body scattering processes. The tensor consists of a damping-like term and
+a correction to the gyromagnetic ratio. Based on electronic structure theory,
+both terms are shown to depend on e.g. the scalar, anisotropic, vector-chiral
+and scalar-chiral products of magnetic moments: $\vec{e}_i\cdot\vec{e}_j$,
+$(\vec{n}_{ij}\cdot\vec{e}_i)(\vec{n}_{ij}\cdot\vec{e}_j)$,
+$\vec{n}_{ij}\cdot(\vec{e}_i\times\vec{e}_j)$, $(\vec{e}_i\cdot\vec{e}_j)^2$,
+$\vec{e}_i\cdot(\vec{e}_j\times\vec{e}_k)$..., where some terms are subjected
+to the spin-orbit field $\vec{n}_{ij}$ in first and second order. We explore
+the magnitude of the different contributions using both the Alexander-Anderson
+model and time-dependent density functional theory in magnetic adatoms and
+dimers deposited on Au(111) surface.",2202.06154v1
+2022-11-23,The fractional Landau-Lifshitz-Gilbert equation,"The dynamics of a magnetic moment or spin are of high interest to
+applications in technology. Dissipation in these systems is therefore of
+importance for improvement of efficiency of devices, such as the ones proposed
+in spintronics. A large spin in a magnetic field is widely assumed to be
+described by the Landau-Lifshitz-Gilbert (LLG) equation, which includes a
+phenomenological Gilbert damping. Here, we couple a large spin to a bath and
+derive a generic (non-)Ohmic damping term for the low-frequency range using a
+Caldeira-Leggett model. This leads to a fractional LLG equation, where the
+first-order derivative Gilbert damping is replaced by a fractional derivative
+of order $s \ge 0$. We show that the parameter $s$ can be determined from a
+ferromagnetic resonance experiment, where the resonance frequency and linewidth
+no longer scale linearly with the effective field strength.",2211.12889v1
+2018-05-04,Effective damping enhancement in noncollinear spin structures,"Damping mechanisms in magnetic systems determine the lifetime, diffusion and
+transport properties of magnons, domain walls, magnetic vortices, and
+skyrmions. Based on the phenomenological Landau-Lifshitz-Gilbert equation, here
+the effective damping parameter in noncollinear magnetic systems is determined
+describing the linewidth in resonance experiments or the decay parameter in
+time-resolved measurements. It is shown how the effective damping can be
+calculated from the elliptic polarization of magnons, arising due to the
+noncollinear spin arrangement. It is concluded that the effective damping is
+larger than the Gilbert damping, and it may significantly differ between
+excitation modes. Numerical results for the effective damping are presented for
+the localized magnons in isolated skyrmions, with parameters based on the
+Pd/Fe/Ir(111) model-type system.",1805.01815v2
+2023-12-14,"Nonlocal damping of spin waves in a magnetic insulator induced by normal, heavy, or altermagnetic metallic overlayer: a Schwinger-Keldysh field theory approach","Understanding spin wave (SW) damping, and how to control it to the point of
+being able to amplify SW-mediated signals, is one of the key requirements to
+bring the envisaged magnonic technologies to fruition. Even widely used
+magnetic insulators with low magnetization damping in their bulk, such as
+yttrium iron garnet, exhibit 100-fold increase in SW damping due to inevitable
+contact with metallic layers in magnonic circuits, as observed in very recent
+experiments [I. Bertelli et al., Adv. Quantum Technol. 4, 2100094 (2021)]
+mapping SW damping in spatially-resolved fashion. Here, we provide microscopic
+and rigorous understanding of wavevector-dependent SW damping using extended
+Landau-Lifshitz-Gilbert equation with nonlocal damping tensor, instead of
+conventional local scalar Gilbert damping, as derived from Schwinger-Keldysh
+nonequilibrium quantum field theory. In this picture, the origin of nonlocal
+magnetization damping and thereby induced wavevector-dependent SW damping is
+interaction of localized magnetic moments of magnetic insulator with conduction
+electrons from the examined three different types of metallic overlayers --
+normal, heavy, and altermagnetic. Due to spin-split energy-momentum dispersion
+of conduction electrons in the latter two cases, the nonlocal damping is
+anisotropic in spin and space, and it can be dramatically reduced by changing
+the relative orientation of the two layers when compared to the usage of normal
+metal overlayer.",2312.09140v1
+2017-03-20,Relativistic theory of magnetic inertia in ultrafast spin dynamics,"The influence of possible magnetic inertia effects has recently drawn
+attention in ultrafast magnetization dynamics and switching. Here we derive
+rigorously a description of inertia in the Landau-Lifshitz-Gilbert equation on
+the basis of the Dirac-Kohn-Sham framework. Using the Foldy-Wouthuysen
+transformation up to the order of $1/c^4$ gives the intrinsic inertia of a pure
+system through the 2$^{\rm nd}$ order time-derivative of magnetization in the
+dynamical equation of motion. Thus, the inertial damping $\mathcal{I}$ is a
+higher order spin-orbit coupling effect, $\sim 1/c^4$, as compared to the
+Gilbert damping $\Gamma$ that is of order $1/c^2$. Inertia is therefore
+expected to play a role only on ultrashort timescales (sub-picoseconds). We
+also show that the Gilbert damping and inertial damping are related to one
+another through the imaginary and real parts of the magnetic susceptibility
+tensor respectively.",1704.01559v1
+2019-07-10,The superior role of the Gilbert damping on the signal-to-noise ratio in heat-assisted magnetic recording,"In magnetic recording the signal-to-noise ratio (SNR) is a good indicator for
+the quality of written bits. However, a priori it is not clear which parameters
+have the strongest influence on the SNR. In this work, we investigate the role
+of the Gilbert damping on the SNR. Grains consisting of FePt like hard magnetic
+material with two different grain sizes $d_1=5\,$nm and $d_2=7\,$nm are
+considered and simulations of heat-assisted magnetic recording (HAMR) are
+performed with the atomistic simulation program VAMPIRE. The simulations
+display that the SNR saturates for damping constants larger or equal than 0.1.
+Additionally, we can show that the Gilbert damping together with the bit length
+have a major effect on the SNR whereas other write head and material parameters
+only have a minor relevance on the SNR.",1907.04577v2
+2019-10-24,Spin waves in ferromagnetic thin films,"A spin wave is the disturbance of intrinsic spin order in magnetic materials.
+In this paper, a spin wave in the Landau-Lifshitz-Gilbert equation is obtained
+based on the assumption that the spin wave maintains its shape while it
+propagates at a constant velocity. Our main findings include: (1) in the
+absence of Gilbert damping, the spin wave propagates at a constant velocity
+with the increment proportional to the strength of the magnetic field; (2) in
+the absence of magnetic field, at a given time the spin wave converges
+exponentially fast to its initial profile as the damping parameter goes to zero
+and in the long time the relaxation dynamics of the spin wave converges
+exponentially fast to the easy-axis direction with the exponent proportional to
+the damping parameter; (3) in the presence of both Gilbert damping and magnetic
+field, the spin wave converges to the easy-axis direction exponentially fast at
+a small timescale while propagates at a constant velocity beyond that. These
+provides a comprehensive understanding of spin waves in ferromagnetic
+materials.",1910.11200v1
+2020-06-30,Negative Gilbert damping in cavity optomagnonics,"Exceptional point (EP) associated with the parity-time (PT) symmetry breaking
+is receiving considerable recent attention by the broad physics community. By
+introducing balanced gain and loss, it has been realized in photonic, acoustic,
+and electronic structures. However, the observation of magnonic EP remains
+elusive. The major challenge is to experimentally generate the negative Gilbert
+damping, which was thought to be highly unlikely but is demanded by the PT
+symmetry. In this work, we study the magneto-optical interaction of
+circularly-polarized lasers with a submicron magnet placed in an optical
+cavity. We show that the off-resonant coupling between the driving laser and
+cavity photon in the far-blue detuning can induce the magnetic gain (or
+negative damping) exactly of the Gilbert type. A hyperbolic-tangent function
+ansatz is found to well describe the time-resolved spin switching as the
+intrinsic magnetization dissipation is overcome. When the optically pumped
+magnet interacts with a purely lossy one, we observe a phase transition from
+the imbalanced to passive PT symmetries by varying the detuning coeffcient. Our
+findings provide a feasible way to manipulate the sign of the magnetic damping
+parameter and to realize the EP in cavity optomagnonics.",2006.16510v1
+2017-11-20,Spin Pumping in Ion-beam Sputtered Co_{2}FeAl/Mo Bilayers:Interfacial Gilbert Damping,"The spin pumping mechanism and associated interfacial Gilbert damping are
+demonstrated in ion-beam sputtered Co2FeAl (CFA) /Mo bilayer thin films
+employing ferromagnetic resonance spectroscopy. The dependence of the net spin
+current transportation on Mo layer thickness, 0 to 10 nm, and the enhancement
+of the net effective Gilbert damping are reported. The experimental data has
+been analyzed using spin pumping theory in terms of spin current pumped through
+the ferromagnet /nonmagnetic metal interface to deduce the effective spin
+mixing conductance and the spin-diffusion length, which are estimated to be
+1.16(0.19)x10^19 m^-2 and 3.50(0.35)nm, respectively. The damping constant is
+found to be 8.4(0.3)x10^-3 in the Mo(3.5nm) capped CFA(8nm) sample
+corresponding to a ~42% enhancement of the original Gilbert damping
+(6.0(0.3)x10^-3) in the uncapped CFA layer. This is further confirmed by
+inserting a Cu dusting layer which reduces the spin transport across the CFA
+/Mo interface. The Mo layer thickness dependent net spin current density is
+found to lie in the range of 1-3 MAm^-2, which also provides additional
+quantitative evidence of spin pumping in this bilayer thin film system.",1711.07455v1
+2008-05-21,Non-equilibrium thermodynamic study of magnetization dynamics in the presence of spin-transfer torque,"The dynamics of magnetization in the presence of spin-transfer torque was
+studied. We derived the equation for the motion of magnetization in the
+presence of a spin current by using the local equilibrium assumption in
+non-equilibrium thermodynamics. We show that, in the resultant equation, the
+ratio of the Gilbert damping constant, $\alpha$, and the coefficient, $\beta$,
+of the current-induced torque, called non-adiabatic torque, depends on the
+relaxation time of the fluctuating field $\tau_{c}$. The equality
+$\alpha=\beta$ holds when $\tau_c$ is very short compared to the time scale of
+magnetization dynamics. We apply our theory to current-induced magnetization
+reversal in magnetic multilayers and show that the switching time is a
+decreasing function of $\tau_{c}$.",0805.3306v1
+2010-08-03,Determination of the spin-flip time in ferromagnetic SrRuO3 from time-resolved Kerr measurements,"We report time-resolved Kerr effect measurements of magnetization dynamics in
+ferromagnetic SrRuO3. We observe that the demagnetization time slows
+substantially at temperatures within 15K of the Curie temperature, which is ~
+150K. We analyze the data with a phenomenological model that relates the
+demagnetization time to the spin flip time. In agreement with our observations
+the model yields a demagnetization time that is inversely proportional to T-Tc.
+We also make a direct comparison of the spin flip rate and the Gilbert damping
+coefficient showing that their ratio very close to kBTc, indicating a common
+origin for these phenomena.",1008.0674v1
+2015-03-26,Thermophoresis of an Antiferromagnetic Soliton,"We study dynamics of an antiferromagnetic soliton under a temperature
+gradient. To this end, we start by phenomenologically constructing the
+stochastic Landau-Lifshitz-Gilbert equation for an antiferromagnet with the aid
+of the fluctuation-dissipation theorem. We then derive the Langevin equation
+for the soliton's center of mass by the collective coordinate approach. An
+antiferromagentic soliton behaves as a classical massive particle immersed in a
+viscous medium. By considering a thermodynamic ensemble of solitons, we obtain
+the Fokker-Planck equation, from which we extract the average drift velocity of
+a soliton. The diffusion coefficient is inversely proportional to a small
+damping constant $\alpha$, which can yield a drift velocity of tens of m/s
+under a temperature gradient of $1$ K/mm for a domain wall in an easy-axis
+antiferromagnetic wire with $\alpha \sim 10^{-4}$.",1503.07854v2
+2016-04-24,Coupled Spin-Light dynamics in Cavity Optomagnonics,"Experiments during the past two years have shown strong resonant
+photon-magnon coupling in microwave cavities, while coupling in the optical
+regime was demonstrated very recently for the first time. Unlike with
+microwaves, the coupling in optical cavities is parametric, akin to
+optomechanical systems. This line of research promises to evolve into a new
+field of optomagnonics, aimed at the coherent manipulation of elementary
+magnetic excitations by optical means. In this work we derive the microscopic
+optomagnonic Hamiltonian. In the linear regime the system reduces to the
+well-known optomechanical case, with remarkably large coupling. Going beyond
+that, we study the optically induced nonlinear classical dynamics of a
+macrospin. In the fast cavity regime we obtain an effective equation of motion
+for the spin and show that the light field induces a dissipative term
+reminiscent of Gilbert damping. The induced dissipation coefficient however can
+change sign on the Bloch sphere, giving rise to self-sustained oscillations.
+When the full dynamics of the system is considered, the system can enter a
+chaotic regime by successive period doubling of the oscillations.",1604.07053v3
+2018-02-07,Breaking the current density threshold in spin-orbit-torque magnetic random access memory,"Spin-orbit-torque magnetic random access memory (SOT-MRAM) is a promising
+technology for the next generation of data storage devices. The main bottleneck
+of this technology is the high reversal current density threshold. This
+outstanding problem of SOT-MRAM is now solved by using a current density of
+constant magnitude and varying flow direction that reduces the reversal current
+density threshold by a factor of more than the Gilbert damping coefficient. The
+Euler-Lagrange equation for the fastest magnetization reversal path and the
+optimal current pulse are derived for an arbitrary magnetic cell. The
+theoretical limit of minimal reversal current density and current density for a
+GHz switching rate of the new reversal strategy for CoFeB/Ta SOT-MRAMs are
+respectively of the order of $10^5$ A/cm$^2$ and $10^6$ A/cm$^2$ far below
+$10^7$ A/cm$^2$ and $10^8$ A/cm$^2$ in the conventional strategy. Furthermore,
+no external magnetic field is needed for a deterministic reversal in the new
+strategy.",1802.02415v1
+2022-04-22,A short-circuited coplanar waveguide for low-temperature single-port ferromagnetic resonance spectroscopy set-up to probe the magnetic properties of ferromagnetic thin films,"A coplanar waveguide shorted in one end is proposed, designed, and
+implemented successfully to measure the properties of magnetic thin films as a
+part of the vector network analyzer ferromagnetic resonance (VNA-FMR)
+spectroscopy set-up. Its simple structure, potential applications and easy
+installation inside the cryostat chamber made it advantageous especially for
+low-temperature measurements. It provides a wide band of frequencies in the
+gigahertz range essential for FMR measurements. Our spectroscopy set-up with
+short-circuited coplanar waveguide has been used to extract Gilbert damping
+coefficient and effective magnetization values for standard ferromagnetic thin
+films like Py and Co. The thickness and temperature dependent studies of those
+magnetic parameters have also been done here for the afore mentioned magnetic
+samples.",2204.10596v2
+2014-04-05,Gilbert damping in noncollinear ferromagnets,"The precession and damping of a collinear magnetization displaced from its
+equilibrium are described by the Landau-Lifshitz-Gilbert equation. For a
+noncollinear magnetization, it is not known how the damping should be
+described. We use first-principles scattering theory to investigate the damping
+in one-dimensional transverse domain walls (DWs) of the important ferromagnetic
+alloy Ni$_{80}$Fe$_{20}$ and interpret the results in terms of phenomenological
+models. The damping is found to depend not only on the magnetization texture
+but also on the specific dynamic modes of Bloch and N\'eel DWs. Even in the
+highly disordered Ni$_{80}$Fe$_{20}$ alloy, the damping is found to be
+remarkably nonlocal.",1404.1488v2
+2019-11-21,Low damping and microstructural perfection of sub-40nm-thin yttrium iron garnet films grown by liquid phase epitaxy,"The field of magnon spintronics is experiencing an increasing interest in the
+development of solutions for spin-wave-based data transport and processing
+technologies that are complementary or alternative to modern CMOS
+architectures. Nanometer-thin yttrium iron garnet (YIG) films have been the
+gold standard for insulator-based spintronics to date, but a potential process
+technology that can deliver perfect, homogeneous large-diameter films is still
+lacking. We report that liquid phase epitaxy (LPE) enables the deposition of
+nanometer-thin YIG films with low ferromagnetic resonance losses and
+consistently high magnetic quality down to a thickness of 20 nm. The obtained
+epitaxial films are characterized by an ideal stoichiometry and perfect film
+lattices, which show neither significant compositional strain nor geometric
+mosaicity, but sharp interfaces. Their magneto-static and dynamic behavior is
+similar to that of single crystalline bulk YIG. We found, that the Gilbert
+damping coefficient alpha is independent of the film thickness and close to 1 x
+10-4, and that together with an inhomogeneous peak-to-peak linewidth broadening
+of delta H0|| = 0.4 G, these values are among the lowest ever reported for YIG
+films with a thickness smaller than 40 nm. These results suggest, that
+nanometer-thin LPE films can be used to fabricate nano- and micro-scaled
+circuits with the required quality for magnonic devices. The LPE technique is
+easily scalable to YIG sample diameters of several inches.",1911.09400v1
+2003-04-04,Dynamic exchange coupling and Gilbert damping in magnetic multilayers,"We theoretically study dynamic properties of thin ferromagnetic films in
+contact with normal metals. Moving magnetizations cause a flow of spins into
+adjacent conductors, which relax by spin flip, scatter back into the
+ferromagnet, or are absorbed by another ferromagnet. Relaxation of spins
+outside the moving magnetization enhances the overall damping of the
+magnetization dynamics in accordance with the Gilbert phenomenology. Transfer
+of spins between different ferromagnets by these nonequilibrium spin currents
+leads to a long-ranged dynamic exchange interaction and novel collective
+excitation modes. Our predictions agree well with recent
+ferromagnetic-resonance experiments on ultrathin magnetic films.",0304116v1
+2012-03-03,Scaling of intrinsic Gilbert damping with spin-orbital coupling strength,"We have experimentally and theoretically investigated the dependence of the
+intrinsic Gilbert damping parameter $\alpha_0$ on the spin-orbital coupling
+strength $\xi$ by using L1$_{\mathrm{0}}$ ordered
+FePd$_{\mathrm{1-x}}$Pt$_{\mathrm{x}}$ ternary alloy films with perpendicular
+magnetic anisotropy. With the time-resolved magneto-optical Kerr effect,
+$\alpha_0$ is found to increase by more than a factor of ten when $x$ varies
+from 0 to 1.0. Since changes of other leading parameters are found to be
+neglected, the $\alpha_0$ has for the first time been proven to be proportional
+to $\xi^2$.",1203.0607v1
+2013-03-20,Spin-pumping and Enhanced Gilbert Damping in Thin Magnetic Insulator Films,"Precessing magnetization in a thin film magnetic insulator pumps spins into
+adjacent metals; however, this phenomenon is not quantitatively understood. We
+present a theory for the dependence of spin-pumping on the transverse mode
+number and in-plane wave vector. For long-wavelength spin waves, the enhanced
+Gilbert damping for the transverse mode volume waves is twice that of the
+macrospin mode, and for surface modes, the enhancement can be ten or more times
+stronger. Spin-pumping is negligible for short-wavelength exchange spin waves.
+We corroborate our analytical theory with numerical calculations in agreement
+with recent experimental results.",1303.4922v1
+2022-06-10,Spin Pumping into Anisotropic Dirac Electrons,"We study spin pumping into an anisotropic Dirac electron system induced by
+microwave irradiation to an adjacent ferromagnetic insulator theoretically. We
+formulate the Gilbert damping enhancement due to the spin current flowing into
+the Dirac electron system using second-order perturbation with respect to the
+interfacial exchange coupling. As an illustration, we consider the anisotropic
+Dirac system realized in bismuth to show that the Gilbert damping varies
+according to the magnetization direction in the ferromagnetic insulator. Our
+results indicate that this setup can provide helpful information on the
+anisotropy of the Dirac electron system.",2206.04899v1
+2023-03-02,Spin Pumping into Carbon Nanotubes,"We theoretically study spin pumping from a ferromagnetic insulator (FI) into
+a carbon nanotube (CNT). By employing the bosonization method, we formulate the
+Gilbert damping induced by the FI/CNT junction, which can be measured by
+ferromagnetic resonance. We show that the increase in the Gilbert damping has a
+temperature dependence characteristic of a Luttinger liquid and is highly
+sensitive to the Luttinger parameter of the spin sector for a clean interface.
+We also discuss the experimental relevance of our findings based on numerical
+estimates, using realistic parameters.",2303.01343v2
+2019-08-29,Enhancement of ultrafast demagnetization rate and Gilbert damping driven by femtosecond laser-induced spin currents in Fe81Ga19/Ir20Mn80 bilayers,"In spintronics applications, ultrafast spin dynamics have to be controlled at
+femtosecond (fs) timescales via fs-laser radiation. At such ultrafast
+timescales, the effect of the Gilbert damping factor {\alpha} on ultrafast
+demagnetization time should be considered. In previous explorations for the
+relationship between these two parameters, it was found that the theoretical
+calculations based on the local spin-flip scattering model do not agree with
+the experimental results. Here, we find that in Fe81Ga19(FeGa)/Ir20Mn80(IrMn)
+bilayers, the unconventional IrMn thickness dependence of {\alpha} results from
+the competition between spin currents pumped from the ferromagnetic (FM) FeGa
+layer to the antiferromagnetic (AFM) IrMn layer and those pumped from the AFM
+layer to the FM layer. More importantly, we establish a proportional
+relationship between the change of the ultrafast demagnetization rate and the
+enhancement of Gilbert damping induced by the spin currents via interfacial
+spin chemical potential . Our work builds a bridge to connect the ultrafast
+demagnetization time and Gilbert damping in ultrafast photo-induced spin
+currents dominated systems, which not only explains the disagreement between
+experimental and theoretical results in the relation of {\tau}_M with {\alpha},
+but provides further insight into ultrafast spin dynamics as well.",1908.11084v1
+2021-09-08,Room-Temperature Intrinsic and Extrinsic Damping in Polycrystalline Fe Thin Films,"We examine room-temperature magnetic relaxation in polycrystalline Fe films.
+Out-of-plane ferromagnetic resonance (FMR) measurements reveal Gilbert damping
+parameters of $\approx$ 0.0024 for Fe films with thicknesses of 4-25 nm,
+regardless of their microstructural properties. The remarkable invariance with
+film microstructure strongly suggests that intrinsic Gilbert damping in
+polycrystalline metals at room temperature is a local property of nanoscale
+crystal grains, with limited impact from grain boundaries and film roughness.
+By contrast, the in-plane FMR linewidths of the Fe films exhibit distinct
+nonlinear frequency dependences, indicating the presence of strong extrinsic
+damping. To fit our in-plane FMR data, we have used a grain-to-grain two-magnon
+scattering model with two types of correlation functions aimed at describing
+the spatial distribution of inhomogeneities in the film. However, neither of
+the two correlation functions is able to reproduce the experimental data
+quantitatively with physically reasonable parameters. Our findings advance the
+fundamental understanding of intrinsic Gilbert damping in structurally
+disordered films, while demonstrating the need for a deeper examination of how
+microstructural disorder governs extrinsic damping.",2109.03684v2
+2006-06-09,Spin wave dynamics and the determination of intrinsic Gilbert damping in locally-excited Permalloy thin films,"Time-resolved scanning Kerr effect microscopy has been used to study
+magnetization dynamics in Permalloy thin films excited by transient magnetic
+pulses generated by a micrometer-scale transmission line structure. The results
+are consistent with magnetostatic spin wave theory and are supported by
+micromagnetic simulations. Magnetostatic volume and surface spin waves are
+measured for the same specimen using different bias field orientations and can
+be accurately calculated by k-space integrations over all excited plane wave
+components. A single damping constant of Gilbert form is sufficient to describe
+both scenarios. The nonuniform pulsed field plays a key role in the spin wave
+dynamics, with its Fourier transform serving as a weighting function for the
+participating modes. The intrinsic Gilbert damping parameter $\alpha$ is most
+conveniently measured when the spin waves are effectively stationary.",0606235v3
+2007-05-10,Effective temperature and Gilbert damping of a current-driven localized spin,"Starting from a model that consists of a semiclassical spin coupled to two
+leads we present a microscopic derivation of the Langevin equation for the
+direction of the spin. For slowly-changing direction it takes on the form of
+the stochastic Landau-Lifschitz-Gilbert equation. We give expressions for the
+Gilbert damping parameter and the strength of the fluctuations, including their
+bias-voltage dependence. At nonzero bias-voltage the fluctuations and damping
+are not related by the fluctuation-dissipation theorem. We find, however, that
+in the low-frequency limit it is possible to introduce a voltage-dependent
+effective temperature that characterizes the fluctuations in the direction of
+the spin, and its transport-steady-state probability distribution function.",0705.1432v3
+2014-12-05,Calculating linear response functions for finite temperatures on the basis of the alloy analogy model,"A scheme is presented that is based on the alloy analogy model and allows to
+account for thermal lattice vibrations as well as spin fluctuations when
+calculating response quantities in solids. Various models to deal with spin
+fluctuations are discussed concerning their impact on the resulting temperature
+dependent magnetic moment, longitudinal conductivity and Gilbert damping
+parameter. It is demonstrated that using the Monte Carlo (MC) spin
+configuration as an input, the alloy analogy model is capable to reproduce
+results of MC simulations on the average magnetic moment within all spin
+fluctuation models under discussion. On the other hand, response quantities are
+much more sensitive to the spin fluctuation model. Separate calculations
+accounting for either the thermal effect due to lattice vibrations or spin
+fluctuations show their comparable contributions to the electrical conductivity
+and Gilbert damping. However, comparison to results accounting for both thermal
+effects demonstrate violation of Matthiessen's rule, showing the non-additive
+effect of lattice vibrations and spin fluctuations. The results obtained for
+bcc Fe and fcc Ni are compared with the experimental data, showing rather good
+agreement for the temperature dependent electrical conductivity and Gilbert
+damping parameter.",1412.1988v1
+2015-10-13,Nonlocal torque operators in ab initio theory of the Gilbert damping in random ferromagnetic alloys,"We present an ab initio theory of the Gilbert damping in substitutionally
+disordered ferromagnetic alloys. The theory rests on introduced nonlocal
+torques which replace traditional local torque operators in the well-known
+torque-correlation formula and which can be formulated within the atomic-sphere
+approximation. The formalism is sketched in a simple tight-binding model and
+worked out in detail in the relativistic tight-binding linear muffin-tin
+orbital (TB-LMTO) method and the coherent potential approximation (CPA). The
+resulting nonlocal torques are represented by nonrandom, non-site-diagonal and
+spin-independent matrices, which simplifies the configuration averaging. The
+CPA-vertex corrections play a crucial role for the internal consistency of the
+theory and for its exact equivalence to other first-principles approaches based
+on the random local torques. This equivalence is also illustrated by the
+calculated Gilbert damping parameters for binary NiFe and FeCo random alloys,
+for pure iron with a model atomic-level disorder, and for stoichiometric FePt
+alloys with a varying degree of L10 atomic long-range order.",1510.03571v2
+2016-12-07,Gilbert damping of magnetostatic modes in a yttrium iron garnet sphere,"The magnetostatic mode (MSM) spectrum of a 300$\mu$m diameter single
+crystalline sphere of yttrium iron garnet is investigated using broadband
+ferromagnetic resonance (FMR). The individual MSMs are identified via their
+characteristic dispersion relations and the corresponding mode number tuples
+$(nmr)$ are assigned. Taking FMR data over a broad frequency and magnetic field
+range allows to analyze both the Gilbert damping parameter~$\alpha$ and the
+inhomogeneous line broadening contribution to the total linewidth of the MSMs
+separately. The linewidth analysis shows that all MSMs share the same Gilbert
+damping parameter $\alpha=2.7(5) \times 10^{-5}$ irrespective of their mode
+index. In contrast, the inhomogeneous line broadening shows a pronounced mode
+dependence. This observation is modeled in terms of two-magnon scattering
+processes of the MSMs into the spin-wave manifold, mediated by surface and
+volume defects.",1612.02360v1
+2018-05-29,Gilbert damping in non-collinear magnetic system,"The modification of the magnetization dissipation or Gilbert damping caused
+by an inhomogeneous magnetic structure and expressed in terms of a wave vector
+dependent tensor $\underline{\alpha}(\vec{q})$ is investigated by means of
+linear response theory. A corresponding expression for
+$\underline{\alpha}(\vec{q})$ in terms of the electronic Green function has
+been developed giving in particular the leading contributions to the Gilbert
+damping linear and quadratic in $q$. Numerical results for realistic systems
+are presented that have been obtained by implementing the scheme within the
+framework of the fully relativistic KKR (Korringa-Kohn-Rostoker) band structure
+method. Using the multilayered system (Cu/Fe$_{1-x}$Co$_x$/Pt)$_n$ as an
+example for systems without inversion symmetry we demonstrate the occurrence of
+non-vanishing linear contributions. For the alloy system bcc Fe$_{1-x}$Co$_x$
+having inversion symmetry, on the other hand, only the quadratic contribution
+is non-zero. As it is shown, this quadratic contribution does not vanish even
+if the spin-orbit coupling is suppressed, i.e.\ it is a direct consequence of
+the non-collinear spin configuration.",1805.11468v1
+2018-10-15,Localized spin waves in isolated $kπ$ skyrmions,"The localized magnon modes of isolated $k\pi$ skyrmions on a field-polarized
+background are analyzed based on the Landau-Lifshitz-Gilbert equation within
+the terms of an atomistic classical spin model, with system parameters based on
+the Pd/Fe biatomic layer on Ir(111). For increasing skyrmion order $k$ a higher
+number of excitation modes are found, including modes with nodes in the radial
+eigenfunctions. It is shown that at low fields $2\pi$ and $3\pi$ skyrmions are
+destroyed via a burst instability connected to a breathing mode, while $1\pi$
+skyrmions undergo an elliptic instability. At high fields all $k\pi$ skyrmions
+collapse due to the instability of a breathing mode. The effective damping
+parameters of the spin waves are calculated in the low Gilbert damping limit,
+and they are found to diverge in the case of the lowest-lying modes at the
+burst and collapse instabilities, but not at the elliptic instability. It is
+shown that the breathing modes of $k\pi$ skyrmions may become overdamped at
+higher Gilbert damping values.",1810.06471v1
+2018-10-24,Nearly isotropic spin-pumping related Gilbert damping in Pt/Ni$_{81}$Fe$_{19}$/Pt,"A recent theory by Chen and Zhang [Phys. Rev. Lett. 114, 126602 (2015)]
+predicts strongly anisotropic damping due to interfacial spin-orbit coupling in
+ultrathin magnetic films. Interfacial Gilbert-type relaxation, due to the spin
+pumping effect, is predicted to be significantly larger for magnetization
+oriented parallel to compared with perpendicular to the film plane. Here, we
+have measured the anisotropy in the Pt/Ni$_{81}$Fe$_{19}$/Pt system via
+variable-frequency, swept-field ferromagnetic resonance (FMR). We find a very
+small anisotropy of enhanced Gilbert damping with sign opposite to the
+prediction from the Rashba effect at the FM/Pt interface. The results are
+contrary to the predicted anisotropy and suggest that a mechanism separate from
+Rashba spin-orbit coupling causes the rapid onset of spin-current absorption in
+Pt.",1810.10595v4
+2019-11-08,Giant anisotropy of Gilbert damping in a Rashba honeycomb antiferromagnet,"Giant Gilbert damping anisotropy is identified as a signature of strong
+Rashba spin-orbit coupling in a two-dimensional antiferromagnet on a honeycomb
+lattice. The phenomenon originates in spin-orbit induced splitting of
+conduction electron subbands that strongly suppresses certain spin-flip
+processes. As a result, the spin-orbit interaction is shown to support an
+undamped non-equilibrium dynamical mode that corresponds to an ultrafast
+in-plane N\'eel vector precession and a constant perpendicular-to-the-plane
+magnetization. The phenomenon is illustrated on the basis of a two dimensional
+$s$-$d$ like model. Spin-orbit torques and conductivity are also computed
+microscopically for this model. Unlike Gilbert damping these quantities are
+shown to reveal only a weak anisotropy that is limited to the semiconductor
+regime corresponding to the Fermi energy staying in a close vicinity of
+antiferromagnetic gap.",1911.03408v1
+2005-05-10,Fluctuation-dissipation considerations and damping models for ferromagnetic materials,"The role of fluctuation-dissipation relations (theorems) for the
+magnetization dynamics with Landau-Lifshitz-Gilbert and Bloch-Bloembergen
+damping terms are discussed. We demonstrate that the use of the Callen-Welton
+fluctuation-dissipation theorem that was proven for Hamiltonian systems can
+give an inconsistent result for magnetic systems with dissipation.",0505259v1
+2018-07-13,Gilbert damping of high anisotropy Co/Pt multilayers,"Using broadband ferromagnetic resonance, we measure the damping parameter of
+[Co(5 \r{A})/Pt(3 \r{A})]${\times 6}$ multilayers whose growth was optimized to
+maximize the perpendicular anisotropy. Structural characterizations indicate
+abrupt interfaces essentially free of intermixing despite the miscible
+character of Co and Pt. Gilbert damping parameters as low as 0.021 can be
+obtained despite a magneto-crystalline anisotropy as large as
+$10^6~\textrm{J/m}^3$. The inhomogeneous broadening accounts for part of the
+ferromagnetic resonance linewidth, indicating some structural disorder leading
+to a equivalent 20 mT of inhomogenity of the effective field. The unexpectedly
+relatively low damping factor indicates that the presence of the Pt heavy metal
+within the multilayer may not be detrimental to the damping provided that
+intermixing is avoided at the Co/Pt interfaces.",1807.04977v1
+2019-08-23,Damping enhancement in coherent ferrite/insulating-paramagnet bilayers,"High-quality epitaxial ferrites, such as low-damping MgAl-ferrite (MAFO), are
+promising nanoscale building blocks for all-oxide heterostructures driven by
+pure spin current. However, the impact of oxide interfaces on spin dynamics in
+such heterostructures remains an open question. Here, we investigate the spin
+dynamics and chemical and magnetic depth profiles of 15-nm-thick MAFO
+coherently interfaced with an isostructural $\approx$1-8-nm-thick overlayer of
+paramagnetic CoCr$_2$O$_4$ (CCO) as an all-oxide model system. Compared to MAFO
+without an overlayer, effective Gilbert damping in MAFO/CCO is enhanced by a
+factor of $>$3, irrespective of the CCO overlayer thickness. We attribute this
+damping enhancement to spin scattering at the $\sim$1-nm-thick chemically
+disordered layer at the MAFO/CCO interface, rather than spin pumping or
+proximity-induced magnetism. Our results indicate that damping in ferrite-based
+heterostructures is strongly influenced by interfacial chemical disorder, even
+if the thickness of the disordered layer is a small fraction of the ferrite
+thickness.",1908.08629v2
+2006-11-23,Analytical solutions for two-level systems with damping,"A method is proposed to transform any analytic solution of the Bloch equation
+into an analytic solution of the Landau-Lifshitz-Gilbert equation. This allows
+for the analytical description of the dynamics of a two level system with
+damping. This method shows that damping turns the linear Schr\""{o}dinger
+equation of a two-level system into a nonlinear Schr\""{o}dinger equation. As
+applications, it is shown that damping has a relatively mild influence on
+self-induced transparency but destroys dynamical localization.",0611238v1
+2023-04-19,Thickness-dependent magnetic properties in Pt[CoNi]n multilayers with perpendicular magnetic anisotropy,"We systematically investigated the Ni and Co thickness-dependent
+perpendicular magnetic anisotropy (PMA) coefficient, magnetic domain
+structures, and magnetization dynamics of Pt(5 nm)/[Co(t_Co nm)/Ni(t_Ni
+nm)]5/Pt(1 nm) multilayers by combining the four standard magnetic
+characterization techniques. The magnetic-related hysteresis loops obtained
+from the field-dependent magnetization M and anomalous Hall resistivity (AHR)
+\r{ho}_xy found that the two serial multilayers with t_Co = 0.2 and 0.3 nm have
+the optimum PMA coefficient K_U well as the highest coercivity H_C at the Ni
+thickness t_Ni = 0.6 nm. Additionally, the magnetic domain structures obtained
+by Magneto-optic Kerr effect (MOKE) microscopy also significantly depend on the
+thickness and K_U of the films. Furthermore, the thickness-dependent linewidth
+of ferromagnetic resonance is inversely proportional to K_U and H_C, indicating
+that inhomogeneous magnetic properties dominate the linewidth. However, the
+intrinsic Gilbert damping constant determined by a linear fitting of
+frequency-dependent linewidth does not depend on Ni thickness and K_U. Our
+results could help promote the PMA [Co/Ni] multilayer applications in various
+spintronic and spin-orbitronic devices.",2304.09366v1
+2017-01-10,Magnetic properties in ultra-thin 3d transition metal alloys II: Experimental verification of quantitative theories of damping and spin-pumping,"A systematic experimental study of Gilbert damping is performed via
+ferromagnetic resonance for the disordered crystalline binary 3d transition
+metal alloys Ni-Co, Ni-Fe and Co-Fe over the full range of alloy compositions.
+After accounting for inhomogeneous linewidth broadening, the damping shows
+clear evidence of both interfacial damping enhancement (by spin pumping) and
+radiative damping. We quantify these two extrinsic contributions and thereby
+determine the intrinsic damping. The comparison of the intrinsic damping to
+multiple theoretical calculations yields good qualitative and quantitative
+agreement in most cases. Furthermore, the values of the damping obtained in
+this study are in good agreement with a wide range of published experimental
+and theoretical values. Additionally, we find a compositional dependence of the
+spin mixing conductance.",1701.02475v1
+2004-12-18,Fluctuations of the Magnetization in Thin Films due to Conduction Electrons,"A detailed analysis of damping and noise due to a {\it sd}-interaction in a
+thin ferromagnetic film sandwiched between two large normal metal layers is
+carried out. The magnetization is shown to obey in general a non-local equation
+of motion which differs from the the Gilbert equation and is extended to the
+non-adiabatic regime. To lowest order in the exchange interaction and in the
+limit where the Gilbert equation applies, we show that the damping term is
+enhanced due to interfacial effects but it also shows oscillations as a
+function of the film thickness. The noise calculation is however carried out to
+all orders in the exchange coupling constant. The ellipticity of the precession
+of the magnetization is taken into account. The damping is shown to have a
+Gilbert form only in the adiabatic limit while the relaxation time becomes
+strongly dependent on the geometry of the thin film. It is also shown that the
+induced noise characteristic of sd-exchange is inherently colored in character
+and depends on the symmetry of the Hamiltonian of the magnetization in the
+film. We show that the sd-noise can be represented in terms of an external
+stochastic field which is white only in the adiabatic regime. The temperature
+is also renormalized by the spin accumulation in the system. For large
+intra-atomic exchange interactions, the Gilbert-Brown equation is no longer
+valid.",0412510v1
+2014-07-02,Spin Waves in Ferromagnetic Insulators Coupled via a Normal Metal,"Herein, we study the spin-wave dispersion and dissipation in a ferromagnetic
+insulator--normal metal--ferromagnetic insulator system. Long-range dynamic
+coupling because of spin pumping and spin transfer lead to collective magnetic
+excitations in the two thin-film ferromagnets. In addition, the dynamic dipolar
+field contributes to the interlayer coupling. By solving the
+Landau-Lifshitz-Gilbert-Slonczewski equation for macrospin excitations and the
+exchange-dipole volume as well as surface spin waves, we compute the effect of
+the dynamic coupling on the resonance frequencies and linewidths of the various
+modes. The long-wavelength modes may couple acoustically or optically. In the
+absence of spin-memory loss in the normal metal, the spin-pumping-induced
+Gilbert damping enhancement of the acoustic mode vanishes, whereas the optical
+mode acquires a significant Gilbert damping enhancement, comparable to that of
+a system attached to a perfect spin sink. The dynamic coupling is reduced for
+short-wavelength spin waves, and there is no synchronization. For intermediate
+wavelengths, the coupling can be increased by the dipolar field such that the
+modes in the two ferromagnetic insulators can couple despite possible small
+frequency asymmetries. The surface waves induced by an easy-axis surface
+anisotropy exhibit much greater Gilbert damping enhancement. These modes also
+may acoustically or optically couple, but they are unaffected by thickness
+asymmetries.",1407.0635v1
+2015-05-15,Reliable Damping of Free Surface Waves in Numerical Simulations,"This paper generalizes existing approaches for free-surface wave damping via
+momentum sinks for flow simulations based on the Navier-Stokes equations. It is
+shown in 2D flow simulations that, to obtain reliable wave damping, the
+coefficients in the damping functions must be adjusted to the wave parameters.
+A scaling law for selecting these damping coefficients is presented, which
+enables similarity of the damping in model- and full-scale. The influence of
+the thickness of the damping layer, the wave steepness, the mesh fineness and
+the choice of the damping coefficients are examined. An efficient approach for
+estimating the optimal damping setup is presented. Results of 3D ship
+resistance computations show that the scaling laws apply to such simulations as
+well, so the damping coefficients should be adjusted for every simulation to
+ensure convergence of the solution in both model and full scale. Finally,
+practical recommendations for the setup of reliable damping in flow simulations
+with regular and irregular free surface waves are given.",1505.04087v2
+2010-12-20,Global attractors for the one dimensional wave equation with displacement dependent damping,"We study the long-time behavior of solutions of the one dimensional wave
+equation with nonlinear damping coefficient. We prove that if the damping
+coefficient function is strictly positive near the origin then this equation
+possesses a global attractor.",1012.4455v1
+2009-04-21,Tensor damping in metallic magnetic multilayers,"The mechanism of spin-pumping, described by Tserkovnyak et al., is formally
+analyzed in the general case of a magnetic multilayer consisting of two or more
+metallic ferromagnetic (FM) films separated by normal metal (NM) layers. It is
+shown that the spin-pumping-induced dynamic coupling between FM layers modifies
+the linearized Gilbert equations in a way that replaces the scalar Gilbert
+damping constant with a nonlocal matrix of Cartesian damping tensors. The
+latter are shown to be methodically calculable from a matrix algebra solution
+of the Valet-Fert transport equations. As an example, explicit analytical
+results are obtained for a 5-layer (spin-valve) of form NM/FM/NM'/FM/NM.
+Comparisons with earlier well known results of Tserkovnyak et al. for the
+related 3-layer FM/NM/FM indicate that the latter inadvertently hid the tensor
+character of the damping, and instead singled out the diagonal element of the
+local damping tensor along the axis normal to the plane of the two
+magnetization vectors. For spin-valve devices of technological interest, the
+influence of the tensor components of the damping on thermal noise or
+spin-torque critical currents are strongly weighted by the relative magnitude
+of the elements of the nonlocal, anisotropic stiffness-field tensor-matrix, and
+for in-plane magnetized spin-valves are generally more sensitive to the
+in-plane element of the damping tensor.",0904.3150v2
+2023-12-20,An effective field theory of damped ferromagnetic systems,"Using the in-in formalism, we generalize the recently constructed
+magnetoelastic EFT arXiv:2112.13873 [hep-th] to describe the damping dynamics
+of ferromagnetic systems at long wavelengths. We find that the standard Gilbert
+damping term naturally arises as the simplest leading-order symmetry-consistent
+non-conservative contribution within the in-in framework. The EFT is easily
+generalized to scenarios with anisotropy and inhomogeneity. In particular, we
+find the classic Landau-Lifshitz damping term emerges when isotropy is broken
+by a constant external background field. This provides a first principle
+explanation for distinguishing the two types of damping dynamics that were
+originally constructed phenomenologically. Furthermore, the EFT framework could
+also incorporate intrinsic anisotropy of the material in a straightforward way
+using the spurion method. For systems with inhomogeneity such as nontrivial
+spin textures, we find that the leading order derivative correction yields the
+generalized Gilbert damping equations that were found in condensed matter
+literature. This shows that the EFT approach enables us to derive the form of
+higher-derivative-order corrections in a systematic way. Lastly, using the
+phonon-magnon coupling deduced in the magnetoelastic EFT, we are able to make a
+prediction for the generic form of the phononic contribution to the damping
+equation.",2312.13093v1
+2015-10-07,"Tunable damping, saturation magnetization, and exchange stiffness of half-Heusler NiMnSb thin films","The half-metallic half-Heusler alloy NiMnSb is a promising candidate for
+applications in spintronic devices due to its low magnetic damping and its rich
+anisotropies. Here we use ferromagnetic resonance (FMR) measurements and
+calculations from first principles to investigate how the composition of the
+epitaxially grown NiMnSb influences the magnetodynamic properties of saturation
+magnetization $M_S$, Gilbert damping $\alpha$, and exchange stiffness $A$.
+$M_S$ and $A$ are shown to have a maximum for stoichiometric composition, while
+the Gilbert damping is minimum. We find excellent quantitative agreement
+between theory and experiment for $M_S$ and $\alpha$. The calculated $A$ shows
+the same trend as the experimental data, but has a larger magnitude.
+Additionally to the unique in-plane anisotropy of the material, these
+tunabilities of the magnetodynamic properties can be taken advantage of when
+employing NiMnSb films in magnonic devices.",1510.01894v1
+2017-08-07,"Chiral damping, chiral gyromagnetism and current-induced torques in textured one-dimensional Rashba ferromagnets","We investigate Gilbert damping, spectroscopic gyromagnetic ratio and
+current-induced torques in the one-dimensional Rashba model with an additional
+noncollinear magnetic exchange field. We find that the Gilbert damping differs
+between left-handed and right-handed N\'eel-type magnetic domain walls due to
+the combination of spatial inversion asymmetry and spin-orbit interaction
+(SOI), consistent with recent experimental observations of chiral damping.
+Additionally, we find that also the spectroscopic $g$ factor differs between
+left-handed and right-handed N\'eel-type domain walls, which we call chiral
+gyromagnetism. We also investigate the gyromagnetic ratio in the Rashba model
+with collinear magnetization, where we find that scattering corrections to the
+$g$ factor vanish for zero SOI, become important for finite spin-orbit
+coupling, and tend to stabilize the gyromagnetic ratio close to its
+nonrelativistic value.",1708.02008v2
+2017-09-14,Intrinsic Damping Phenomena from Quantum to Classical Magnets:An ab-initio Study of Gilbert Damping in Pt/Co Bilayer,"A fully quantum mechanical description of the precessional damping of Pt/Co
+bilayer is presented in the framework of the Keldysh Green function approach
+using {\it ab initio} electronic structure calculations. In contrast to
+previous calculations of classical Gilbert damping ($\alpha_{GD}$), we
+demonstrate that $\alpha_{GD}$ in the quantum case does not diverge in the
+ballistic regime due to the finite size of the total spin, $S$. In the limit of
+$S\rightarrow\infty$ we show that the formalism recovers the torque correlation
+expression for $\alpha_{GD}$ which we decompose into spin-pumping and
+spin-orbital torque correlation contributions. The formalism is generalized to
+take into account a self consistently determined dephasing mechanism which
+preserves the conservation laws and allows the investigation of the effect of
+disorder. The dependence of $\alpha_{GD}$ on Pt thickness and disorder strength
+is calculated and the spin diffusion length of Pt and spin mixing conductance
+of the bilayer are determined and compared with experiments.",1709.04911v2
+2018-04-02,Anisotropic Gilbert damping in perovskite La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ thin film,"The viscous Gilbert damping parameter governing magnetization dynamics is of
+primary importance for various spintronics applications. Although, the damping
+constant is believed to be anisotropic by theories. It is commonly treated as a
+scalar due to lack of experimental evidence. Here, we present an elaborate
+angle dependent broadband ferromagnetic resonance study of high quality
+epitaxial La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ films. Extrinsic effects are suppressed
+and we show convincing evidence of anisotropic damping with twofold symmetry at
+room temperature. The observed anisotropic relaxation is attributed to the
+magnetization orientation dependence of the band structure. In addition, we
+demonstrated that such anisotropy can be tailored by manipulating the stain.
+This work provides new insights to understand the mechanism of magnetization
+relaxation.",1804.00554v1
+2006-02-03,Microscopic description of Landau-Lifshitz-Gilbert type equation based on the s-d model,"A Landau-Lifshitz-Gilbert type equation has been derived by using s-d model
+in which the s-electron system is regarded as an environment coupled weakly
+with the localized spins. Based on the irreducible linear response theory, we
+show that the relaxation function of the s-electron spin leads to the Gilbert
+type damping term which corresponds to the retarded resistance function in the
+generalized Langevin equation. The Ohmic form of the Gilbert term stems from
+the fact that the imaginary part of the response function (spin susceptibility)
+of the itinerant electron system is proportional to the frequency (omega) in
+the low omega region. It is confirmed that the Caldeira-Leggett theory based on
+the path-integral approach gives the same result.",0602075v2
+2014-09-08,Self-similar solutions of the one-dimensional Landau-Lifshitz-Gilbert equation,"We consider the one-dimensional Landau-Lifshitz-Gilbert (LLG) equation, a
+model describing the dynamics for the spin in ferromagnetic materials. Our main
+aim is the analytical study of the bi-parametric family of self-similar
+solutions of this model. In the presence of damping, our construction provides
+a family of global solutions of the LLG equation which are associated to a
+discontinuous initial data of infinite (total) energy, and which are smooth and
+have finite energy for all positive times. Special emphasis will be given to
+the behaviour of this family of solutions with respect to the Gilbert damping
+parameter.
+  We would like to emphasize that our analysis also includes the study of
+self-similar solutions of the Schr\""odinger map and the heat flow for harmonic
+maps into the 2-sphere as special cases. In particular, the results presented
+here recover some of the previously known results in the setting of the
+1d-Schr\""odinger map equation.",1409.2340v1
+2017-09-12,Green's function formalism for spin transport in metal-insulator-metal heterostructures,"We develop a Green's function formalism for spin transport through
+heterostructures that contain metallic leads and insulating ferromagnets. While
+this formalism in principle allows for the inclusion of various magnonic
+interactions, we focus on Gilbert damping. As an application, we consider
+ballistic spin transport by exchange magnons in a metal-insulator-metal
+heterostructure with and without disorder. For the former case, we show that
+the interplay between disorder and Gilbert damping leads to spin current
+fluctuations. For the case without disorder, we obtain the dependence of the
+transmitted spin current on the thickness of the ferromagnet. Moreover, we show
+that the results of the Green's function formalism agree in the clean and
+continuum limit with those obtained from the linearized stochastic
+Landau-Lifshitz-Gilbert equation. The developed Green's function formalism is a
+natural starting point for numerical studies of magnon transport in
+heterostructures that contain normal metals and magnetic insulators.",1709.03775v1
+2019-09-06,The interplay of large two-magnon ferromagnetic resonance linewidths and low Gilbert damping in Heusler thin films,"We report on broadband ferromagnetic resonance linewidth measurements
+performed on epitaxial Heusler thin films. A large and anisotropic two-magnon
+scattering linewidth broadening is observed for measurements with the
+magnetization lying in the film plane, while linewidth measurements with the
+magnetization saturated perpendicular to the sample plane reveal low Gilbert
+damping constants of $(1.5\pm0.1)\times 10^{-3}$, $(1.8\pm0.2)\times 10^{-3}$,
+and $<8\times 10^{-4}$ for Co$_2$MnSi/MgO, Co$_2$MnAl/MgO, and Co$_2$FeAl/MgO,
+respectively. The in-plane measurements are fit to a model combining Gilbert
+and two-magnon scattering contributions to the linewidth, revealing a
+characteristic disorder lengthscale of 10-100 nm.",1909.02738v2
+2010-02-17,Measurement of Gilbert damping parameters in nanoscale CPP-GMR spin-valves,"In-situ, device level measurement of thermal mag-noise spectral linewidths in
+60nm diameter CPP-GMR spin-valve stacks of IrMn/ref/Cu/free, with reference and
+free layer of similar CoFe/CoFeGe alloy, are used to simultaneously determine
+the intrinsic Gilbert damping for both magnetic layers. It is shown that
+careful alignment at a ""magic-angle"" between free and reference layer static
+equilibrium magnetization can allow direct measurement of the broadband
+intrinsic thermal spectra in the virtual absence of spin-torque effects which
+otherwise grossly distort the spectral line shapes and require linewidth
+extrapolations to zero current (which are nonetheless also shown to agree well
+with the direct method). The experimental magic-angle spectra are shown to be
+in good qualitative and quantitative agreement with both macrospin calculations
+and micromagnetic eigenmode analysis. Despite similar composition and
+thickness, it is repeatedly found that the IrMn exchange pinned reference layer
+has ten times larger intrinsic Gilbert damping (alpha ~ 0.1) than that of the
+free-layer (alpha ~ 0.01). It is argued that the large reference layer damping
+results from strong, off -resonant coupling to to lossy modes of an IrMn/ref
+couple, rather than commonly invoked two-magnon processes.",1002.3295v1
+2018-09-28,Isotropic non-local Gilbert damping driven by spin currents in epitaxial Pd/Fe/MgO(001) films,"Although both theoretical predications and experimental observations
+demonstrated that the damping factor is anisotropic at
+ferromagnet/semiconductor interface with robust interfacial spin-orbit
+coupling, it is not well understood whether non-local Gilbert damping driven by
+spin currents in heavy metal/ferromagnetic metal (HM/FM) bilayers is
+anisotropic or not. Here, we investigated the in-plane angular- and frequency-
+dependence of magnetic relaxation of epitaxial Fe/MgO(001) films with different
+capping layers of Pd and Cu. After disentangling the parasitic contributions,
+such as two-magnon scattering (TMS), mosaicity, and field-dragging effect, we
+unambiguously observed that both local and non-local Gilbert damping are
+isotropic in Fe(001) plane, suggesting that the pure spin currents absorption
+is independent of Fe magnetization orientation in the epitaxial Pd/Fe
+heterostructure. First principles calculation reveals that the effective spin
+mixing conductance of Pd/Fe interface is nearly invariant for different
+magnetization directions in good agreement with the experimental observations.
+These results offer a valuable insight into the transmission and absorption of
+pure spin currents, and facilitate us to utilize next-generation spintronic
+devices.",1809.11020v1
+2004-09-24,Minimal field requirement in precessional magnetization switching,"We investigate the minimal field strength in precessional magnetization
+switching using the Landau-Lifshitz-Gilbert equation in under-critically damped
+systems. It is shown that precessional switching occurs when localized
+trajectories in phase space become unlocalized upon application of field
+pulses. By studying the evolution of the phase space, we obtain the analytical
+expression of the critical switching field in the limit of small damping for a
+magnetic object with biaxial anisotropy. We also calculate the switching times
+for the zero damping situation. We show that applying field along the medium
+axis is good for both small field and fast switching times.",0409671v1
+2011-11-04,Tunable magnetization relaxation in spin valves,"In spin values the damping parameters of the free layer are determined
+non-locally by the entire magnetic configuration. In a dual spin valve
+structure that comprises a free layer embedded between two pinned layers, the
+spin pumping mechanism, in combination with the angular momentum conservation,
+renders the tensor-like damping parameters tunable by varying the interfacial
+and diffusive properties. Simulations based on the Landau-Lifshitz-Gilbert
+phenomenology for a macrospin model are performed with the tensor-like damping
+and the relaxation time of the free layer magnetization is found to be largely
+dependent on while tunable through the magnetic configuration of the
+source-drain magnetization.",1111.1219v1
+2012-05-25,Spin wave amplification driven by heat flow: the role of damping and exchange interaction,"In this article we report on micromagnetic simulations performed on a
+permalloy nanostructure in presence of a uniform thermal gradient. Our
+numerical simulations show that heat flow is an effective mean to compensate
+the damping, and that the gradients at which spin-wave amplification is
+observed are experimentally accessible. In particular, we have studied the role
+of the Gilbert damping parameter on spin-wave amplification.",1205.5650v2
+2015-04-23,Magnetization damping in noncollinear spin valves with antiferromagnetic interlayer couplings,"We study the magnetic damping in the simplest of synthetic antiferromagnets,
+i.e. antiferromagnetically exchange-coupled spin valves in which applied
+magnetic fields tune the magnetic configuration to become noncollinear. We
+formulate the dynamic exchange of spin currents in a noncollinear texture based
+on the spindiffusion theory with quantum mechanical boundary conditions at the
+ferrromagnet|normal-metal interfaces and derive the Landau-Lifshitz-Gilbert
+equations coupled by the static interlayer non-local and the dynamic exchange
+interactions. We predict non-collinearity-induced additional damping that can
+be sensitively modulated by an applied magnetic field. The theoretical results
+compare favorably with published experiments.",1504.06042v1
+2016-05-05,Theory of magnon motive force in chiral ferromagnets,"We predict that magnon motive force can lead to temperature dependent,
+nonlinear chiral damping in both conducting and insulating ferromagnets. We
+estimate that this damping can significantly influence the motion of skyrmions
+and domain walls at finite temperatures. We also find that in systems with low
+Gilbert damping moving chiral magnetic textures and resulting magnon motive
+forces can induce large spin and energy currents in the transverse direction.",1605.01694v2
+2018-04-19,Damping of magnetization dynamics by phonon pumping,"We theoretically investigate pumping of phonons by the dynamics of a magnetic
+film into a non-magnetic contact. The enhanced damping due to the loss of
+energy and angular momentum shows interference patterns as a function of
+resonance frequency and magnetic film thickness that cannot be described by
+viscous (""Gilbert"") damping. The phonon pumping depends on magnetization
+direction as well as geometrical and material parameters and is observable,
+e.g., in thin films of yttrium iron garnet on a thick dielectric substrate.",1804.07080v2
+2024-01-22,Damping-Enhanced Magnon Transmission,"The inevitable Gilbert damping in magnetization dynamics is usually regarded
+as detrimental to spin transport. Here we demonstrate in a
+ferromagnetic-insulator--normal-metal heterostructure that the strong momentum
+dependence and chirality of the eddy-current-induced damping causes also
+beneficial scattering properties. Here we show that a potential barrier that
+reflects magnon wave packets becomes transparent in the presence of a metallic
+cap layer, but only in one direction. We formulate the unidirectional
+transmission in terms of a generalized group velocity with an imaginary
+component and the magnon skin effect. This trick to turn presumably harmful
+dissipation into useful functionalities should be useful for future quantum
+magnonic devices.",2401.12022v1
+2013-05-03,"Co2 FeAl thin films grown on MgO substrates: Correlation between static, dynamic and structural properties","Co2FeAl (CFA) thin films with thickness varying from 10 nm to 115 nm have
+been deposited on MgO(001) substrates by magnetron sputtering and then capped
+by Ta or Cr layer. X-rays diffraction (XRD) revealed that the cubic $[001]$ CFA
+axis is normal to the substrate and that all the CFA films exhibit full
+epitaxial growth. The chemical order varies from the $B2$ phase to the $A2$
+phase when decreasing the thickness. Magneto-optical Kerr effect (MOKE) and
+vibrating sample magnetometer measurements show that, depending on the field
+orientation, one or two-step switchings occur. Moreover, the films present a
+quadratic MOKE signal increasing with the CFA thickness, due to the increasing
+chemical order. Ferromagnetic resonance, MOKE transverse bias initial inverse
+susceptibility and torque (TBIIST) measurements reveal that the in-plane
+anisotropy results from the superposition of a uniaxial and of a fourfold
+symmetry term. The fourfold anisotropy is in accord with the crystal structure
+of the samples and is correlated to the biaxial strain and to the chemical
+order present in the films. In addition, a large negative perpendicular
+uniaxial anisotropy is observed. Frequency and angular dependences of the FMR
+linewidth show two magnon scattering and mosaicity contributions, which depend
+on the CFA thickness. A Gilbert damping coefficient as low as 0.0011 is found.",1305.0714v1
+2016-08-29,Sub-micrometer yttrium iron garnet LPE films with low ferromagnetic resonance losses,"Using liquid phase epitaxy (LPE) technique (111) yttrium iron garnet (YIG)
+films with thicknesses of ~100 nm and surface roughnesses as low as 0.3 nm have
+been grown as a basic material for spin-wave propagation experiments in
+microstructured waveguides. The continuously strained films exhibit nearly
+perfect crystallinity without significant mosaicity and with effective lattice
+misfits of delta a(perpendicular)/a(substrate) ~10-4 and below. The
+film/substrate interface is extremely sharp without broad interdiffusion layer
+formation. All LPE films exhibit a nearly bulk-like saturation magnetization of
+(1800+-20) Gs and an `easy cone' anisotropy type with extremely small in-plane
+coercive fields <0.2 Oe. There is a rather weak in-plane magnetic anisotropy
+with a pronounced six-fold symmetry observed for saturation field <1.5 Oe. No
+significant out-of-plane anisotropy is observed, but a weak dependence of the
+effective magnetization on the lattice misfit is detected. The narrowest
+ferromagnetic resonance linewidth is determined to be 1.4 Oe @ 6.5 GHz which is
+the lowest value reported so far for YIG films of 100 nm thicknesses and below.
+The Gilbert damping coefficient for investigated LPE films is estimated to be
+close to 1 x 10-4.",1608.08043v1
+2019-09-12,Spin Transport in Thick Insulating Antiferromagnetic Films,"Spin transport of magnonic excitations in uniaxial insulating
+antiferromagnets (AFs) is investigated. In linear response to spin biasing and
+a temperature gradient, the spin transport properties of
+normal-metal--insulating antiferromagnet--normal-metal heterostructures are
+calculated. We focus on the thick-film regime, where the AF is thicker than the
+magnon equilibration length. This regime allows the use of a drift-diffusion
+approach, which is opposed to the thin-film limit considered by Bender {\it et
+al.} 2017, where a stochastic approach is justified. We obtain the temperature-
+and thickness-dependence of the structural spin Seebeck coefficient
+$\mathcal{S}$ and magnon conductance $\mathcal{G}$. In their evaluation we
+incorporate effects from field- and temperature-dependent spin conserving
+inter-magnon scattering processes. Furthermore, the interfacial spin transport
+is studied by evaluating the contact magnon conductances in a microscopic model
+that accounts for the sub-lattice symmetry breaking at the interface. We find
+that while inter-magnon scattering does slightly suppress the spin Seebeck
+effect, transport is generally unaffected, with the relevant spin decay length
+being determined by non-magnon-conserving processes such as Gilbert damping. In
+addition, we find that while the structural spin conductance may be enhanced
+near the spin flip transition, it does not diverge due to spin impedance at the
+normal metal|magnet interfaces.",1909.05881v2
+2020-09-22,Magnon-mediated spin currents in Tm3Fe5O12/Pt with perpendicular magnetic anisotropy,"The control of pure spin currents carried by magnons in magnetic insulator
+(MI) garnet films with a robust perpendicular magnetic anisotropy (PMA) is of
+great interest to spintronic technology as they can be used to carry, transport
+and process information. Garnet films with PMA present labyrinth domain
+magnetic structures that enrich the magnetization dynamics, and could be
+employed in more efficient wave-based logic and memory computing devices. In
+MI/NM bilayers, where NM being a normal metal providing a strong spin-orbit
+coupling, the PMA benefits the spin-orbit torque (SOT) driven magnetization's
+switching by lowering the needed current and rendering the process faster,
+crucial for developing magnetic random-access memories (SOT-MRAM). In this
+work, we investigated the magnetic anisotropies in thulium iron garnet (TIG)
+films with PMA via ferromagnetic resonance measurements, followed by the
+excitation and detection of magnon-mediated pure spin currents in TIG/Pt driven
+by microwaves and heat currents. TIG films presented a Gilbert damping constant
+{\alpha}~0.01, with resonance fields above 3.5 kOe and half linewidths broader
+than 60 Oe, at 300 K and 9.5 GHz. The spin-to-charge current conversion through
+TIG/Pt was observed as a micro-voltage generated at the edges of the Pt film.
+The obtained spin Seebeck coefficient was 0.54 {\mu}V/K, confirming also the
+high interfacial spin transparency.",2009.10299v1
+2021-03-08,Emerging magnetic nutation,"Nutation has been recognized as of great significance for spintronics; but
+justifying its presence has proven to be a hard problem. In this paper we show
+that nutation can be understood as emerging from a systematic expansion of a
+kernel that describes the history of the interaction of a magnetic moment with
+a bath of colored noise. The parameter of the expansion is the ratio of the
+colored noise timescale to the precession period. In the process we obtain the
+Gilbert damping from the same expansion. We recover the known results, when the
+coefficients of the two terms are proportional to one another, in the white
+noise limit; and show how colored noise leads to situations where this simple
+relation breaks down, but what replaces it can be understood by the appropriate
+generalization of the fluctuation--dissipation theorem. Numerical simulations
+of the stochastic equations support the analytic approach. In particular we
+find that the equilibration time is about an order of magnitude longer than the
+timescale set by the colored noise for a wide range of values of the latter and
+we can identify the presence of nutation in the non-uniform way the
+magnetization approaches equilibrium.",2103.04787v3
+2008-11-04,Amplitude-Phase Coupling in a Spin-Torque Nano-Oscillator,"The spin-torque nano-oscillator in the presence of thermal fluctuation is
+described by the normal form of the Hopf bifurcation with an additive white
+noise. By the application of the reduction method, the amplitude-phase coupling
+factor, which has a significant effect on the power spectrum of the spin-torque
+nano-oscillator, is calculated from the Landau-Lifshitz-Gilbert-Slonczewski
+equation with the nonlinear Gilbert damping. The amplitude-phase coupling
+factor exhibits a large variation depending on in-plane anisotropy under the
+practical external fields.",0811.0425v1
+2013-09-28,High-efficiency GHz frequency doubling without power threshold in thin-film Ni81Fe19,"We demonstrate efficient second-harmonic generation at moderate input power
+for thin film Ni81Fe19 undergoing ferromagnetic resonance (FMR). Powers of the
+generated second-harmonic are shown to be quadratic in input power, with an
+upconversion ratio three orders of magnitude higher than that demonstrated in
+ferrite. The second harmonic signal generated exhibits a significantly lower
+linewidth than that predicted by low-power Gilbert damping, and is excited
+without threshold. Results are in good agreement with an analytic, approximate
+expansion of the Landau-Lifshitz-Gilbert (LLG) equation.",1309.7483v1
+2016-06-30,Skyrmion dynamics in a chiral magnet driven by periodically varying spin currents,"In this work, we investigated the spin dynamics in a slab of chiral magnets
+induced by an alternating (ac) spin current. Periodic trajectories of the
+skyrmion in real space are discovered under the ac current as a result of the
+Magnus and viscous forces, which originate from the Gilbert damping, the spin
+transfer torque, and the $ \beta $-nonadiabatic torque effects. The results are
+obtained by numerically solving the Landau-Lifshitz-Gilbert equation and can be
+explained by the Thiele equation characterizing the skyrmion core motion.",1606.09326v2
+2018-03-19,Dynamics of a Magnetic Needle Magnetometer: Sensitivity to Landau-Lifshitz-Gilbert Damping,"An analysis of a single-domain magnetic needle in the presence of an external
+magnetic field ${\bf B}$ is carried out with the aim of achieving a high
+precision magnetometer. We determine the uncertainty $\Delta B$ of such a
+device due to Gilbert dissipation and the associated internal magnetic field
+fluctuations that gives rise to diffusion of the magnetic needle axis direction
+${\bf n}$ and the needle orbital angular momentum. The levitation of the
+magnetic needle in a magnetic trap and its stability are also analyzed.",1803.10064v2
+2020-08-27,Nutation Resonance in Ferromagnets,"The inertial dynamics of magnetization in a ferromagnet is investigated
+theoretically. The analytically derived dynamic response upon microwave
+excitation shows two peaks: ferromagnetic and nutation resonances. The exact
+analytical expressions of frequency and linewidth of the magnetic nutation
+resonance are deduced from the frequency dependent susceptibility determined by
+the inertial Landau-Lifshitz-Gilbert equation. The study shows that the
+dependence of nutation linewidth on the Gilbert precession damping has a
+minimum, which becomes more expressive with increase of the applied magnetic
+field.",2008.12221v3
+2009-08-05,Persistence effects in deterministic diffusion,"In systems which exhibit deterministic diffusion, the gross parameter
+dependence of the diffusion coefficient can often be understood in terms of
+random walk models. Provided the decay of correlations is fast enough, one can
+ignore memory effects and approximate the diffusion coefficient according to
+dimensional arguments. By successively including the effects of one and two
+steps of memory on this approximation, we examine the effects of
+``persistence'' on the diffusion coefficients of extended two-dimensional
+billiard tables and show how to properly account for these effects, using walks
+in which a particle undergoes jumps in different directions with probabilities
+that depend on where they came from.",0908.0600v1
+2009-08-10,Diffusion coefficients for multi-step persistent random walks on lattices,"We calculate the diffusion coefficients of persistent random walks on
+lattices, where the direction of a walker at a given step depends on the memory
+of a certain number of previous steps. In particular, we describe a simple
+method which enables us to obtain explicit expressions for the diffusion
+coefficients of walks with two-step memory on different classes of one-, two-
+and higher-dimensional lattices.",0908.1271v1
+2007-02-01,Adiabatic Domain Wall Motion and Landau-Lifshitz Damping,"Recent theory and measurements of the velocity of current-driven domain walls
+in magnetic nanowires have re-opened the unresolved question of whether
+Landau-Lifshitz damping or Gilbert damping provides the more natural
+description of dissipative magnetization dynamics. In this paper, we argue that
+(as in the past) experiment cannot distinguish the two, but that
+Landau-Lifshitz damping nevertheless provides the most physically sensible
+interpretation of the equation of motion. From this perspective, (i) adiabatic
+spin-transfer torque dominates the dynamics with small corrections from
+non-adiabatic effects; (ii) the damping always decreases the magnetic free
+energy, and (iii) microscopic calculations of damping become consistent with
+general statistical and thermodynamic considerations.",0702020v3
+2009-04-09,Evaluating the locality of intrinsic precession damping in transition metals,"The Landau-Lifshitz-Gilbert damping parameter is typically assumed to be a
+local quantity, independent of magnetic configuration. To test the validity of
+this assumption we calculate the precession damping rate of small amplitude
+non-uniform mode magnons in iron, cobalt, and nickel. At scattering rates
+expected near and above room temperature, little change in the damping rate is
+found as the magnon wavelength is decreased from infinity to a length shorter
+than features probed in recent experiments. This result indicates that
+non-local effects due to the presence of weakly non-uniform modes, expected in
+real devices, should not appreciably affect the dynamic response of the element
+at typical operating temperatures. Conversely, at scattering rates expected in
+very pure samples around cryogenic temperatures, non-local effects result in an
+order of magnitude decrease in damping rates for magnons with wavelengths
+commensurate with domain wall widths. While this low temperature result is
+likely of little practical importance, it provides an experimentally testable
+prediction of the non-local contribution of the spin-orbit torque-correlation
+model of precession damping. None of these results exhibit strong dependence on
+the magnon propagation direction.",0904.1455v1
+2018-02-15,Damping's effect on the magnetodynamics of spin Hall nano-oscillators,"We study the impact of spin wave damping ($\alpha$) on the auto-oscillation
+properties of nano-constriction based spin Hall nano-oscillators (SHNOs). The
+SHNOs are based on a 5 nm Pt layer interfaced to a 5 nm
+Py$_{100-x-y}$Pt$_{x}$Ag$_{y}$ magnetic layer, where the Pt and Ag contents are
+co-varied to keep the saturation magnetization constant (within 10 %), while
+$\alpha$ varies close to a factor of three. We systematically investigate the
+influence of the Gilbert damping on the magnetodynamics of these SHNOs by means
+of electrical microwave measurements. Under the condition of a constant field,
+the threshold current scales with the damping in the magnetic layer. The
+threshold current as a function of field shows a parabolic-like behavior, which
+we attribute to the evolution of the spatial profile of the auto-oscillation
+mode. The signal linewidth is smaller for the high-damping materials in low
+magnetic fields, although the lowest observed linewidth was measured for the
+alloy with least damping.",1802.05548v1
+2004-05-02,Spin Dynamics and Multiple Reflections in Ferromagnetic Film in Contact with Normal Metal Layers,"Spin dynamics of a metallic ferromagnetic film imbedded between normal metal
+layers is studied using the spin-pumping theory of Tserkovnyak et al. [Phys.
+Rev. Lett. 88, 117601 (2002)]. The scattering matrix for this structure is
+obtained using a spin-dependent potential with quantum well in the
+ferromagnetic region. Owing to multiple reflections in the well, the excess
+Gilbert damping and the gyromagnetic ratio exhibit quantum oscillations as a
+function of the thickness of the ferromagnetic film. The wavelength of the
+oscillations is given by the depth of the quantum well. For iron film imbedded
+between gold layers, the amplitude of the oscillations of the Gilbert damping
+is in an order of magnitude agreement with the damping observed by Urban et al.
+[Phys. Rev. Lett. 87, 217204 (2001)]. The results are compared with the linear
+response theory of Mills [Phys. Rev. B 68, 0144419 (2003)].",0405020v1
+2004-06-18,Spin pumping and magnetization dynamics in ferromagnet-Luttinger liquid junctions,"We study spin transport between a ferromagnet with time-dependent
+magnetization and a conducting carbon nanotube or quantum wire, modeled as a
+Luttinger liquid. The precession of the magnetization vector of the ferromagnet
+due for instance to an outside applied magnetic field causes spin pumping into
+an adjacent conductor. Conversely, the spin injection causes increased
+magnetization damping in the ferromagnet. We find that, if the conductor
+adjacent to the ferromagnet is a Luttinger liquid, spin pumping/damping is
+suppressed by interactions, and the suppression has clear Luttinger liquid
+power law temperature dependence. We apply our result to a few particular
+setups. First we study the effective Landau-Lifshitz-Gilbert (LLG) coupled
+equations for the magnetization vectors of the two ferromagnets in a FM-LL-FM
+junction. Also, we compute the Gilbert damping for a FM-LL and a FM-LL-metal
+junction.",0406437v1
+2004-10-30,Dynamics of Domain Wall in a Biaxial Ferromagnet With Spin-torque,"The dynamics of the domain wall (DW) in a biaxial ferromagnet interacting
+with a spin-polarized current are described by sine-gordon (SG) equation
+coupled with Gilbert damping term in this paper. Within our frame-work of this
+model, we obtain a threshold of the current in the motion of a single DW with
+the perturbation theory on kink soliton solution to the corresponding
+ferromagnetic system, and the threshold is shown to be dependent on the Gilbert
+damping term. Also, the motion properties of the DW are discussed for the zero-
+and nonzero-damping cases, which shows that our theory to describe the dynamics
+of the DW are self-consistent.",0411005v3
+2005-10-31,Time-Resolved Spin Torque Switching and Enhanced Damping in Py/Cu/Py Spin-Valve Nanopillars,"We report time-resolved measurements of current-induced reversal of a free
+magnetic layer in Py/Cu/Py elliptical nanopillars at temperatures T = 4.2 K to
+160 K. Comparison of the data to Landau-Lifshitz-Gilbert macrospin simulations
+of the free layer switching yields numerical values for the spin torque and the
+Gilbert damping parameters as functions of T. The damping is strongly
+T-dependent, which we attribute to the antiferromagnetic pinning behavior of a
+thin permalloy oxide layer around the perimeter of the free layer. This
+adventitious antiferromagnetic pinning layer can have a major impact on spin
+torque phenomena.",0510798v2
+2006-09-18,General Form of Magnetization Damping: Magnetization dynamics of a spin system evolving nonadiabatically and out of equilibrium,"Using an effective Hamiltonian including the Zeeman and internal
+interactions, we describe the quantum theory of magnetization dynamics when the
+spin system evolves non-adiabatically and out of equilibrium. The
+Lewis-Riesenfeld dynamical invariant method is employed along with the
+Liouville-von Neumann equation for the density matrix. We derive a dynamical
+equation for magnetization defined with respect to the density operator with a
+general form of magnetization damping that involves the non-equilibrium
+contribution in addition to the Landau-Lifshitz-Gilbert equation. Two special
+cases of the radiation-spin interaction and the spin-spin exchange interaction
+are considered. For the radiation-spin interaction, the damping term is shown
+to be of the Gilbert type, while in the spin-spin exchange interaction case the
+results depend on a coupled chain of correlation functions.",0609431v2
+2010-12-25,Screw-pitch effect and velocity oscillation of domain-wall in ferromagnetic nanowire driven by spin-polarized current,"We investigate the dynamics of domain wall in ferromagnetic nanowire with
+spin-transfer torque. The critical current condition is obtained analytically.
+Below the critical current, we get the static domain wall solution which shows
+that the spin-polarized current can't drive domain wall moving continuously. In
+this case, the spin-transfer torque plays both the anti-precession and
+anti-damping roles, which counteracts not only the spin-precession driven by
+the effective field but also Gilbert damping to the moment. Above the critical
+value, the dynamics of domain wall exhibits the novel screw-pitch effect
+characterized by the temporal oscillation of domain wall velocity and width,
+respectively. Both the theoretical analysis and numerical simulation
+demonstrate that this novel phenomenon arise from the conjunctive action of
+Gilbert-damping and spin-transfer torque. We also find that the roles of
+spin-transfer torque are entirely contrary for the cases of below and above the
+critical current.",1012.5473v1
+2014-06-24,Interface enhancement of Gilbert damping from first-principles,"The enhancement of Gilbert damping observed for Ni80Fe20 (Py) films in
+contact with the non-magnetic metals Cu, Pd, Ta and Pt, is quantitatively
+reproduced using first-principles scattering theory. The ""spin-pumping"" theory
+that qualitatively explains its dependence on the Py thickness is generalized
+to include a number of factors known to be important for spin transport through
+interfaces. Determining the parameters in this theory from first-principles
+shows that interface spin-flipping makes an essential contribution to the
+damping enhancement. Without it, a much shorter spin-flip diffusion length for
+Pt would be needed than the value we calculate independently.",1406.6225v2
+2015-09-06,Study of spin dynamics and damping on the magnetic nanowire arrays with various nanowire widths,"We investigate the spin dynamics including Gilbert damping in the
+ferromagnetic nanowire arrays. We have measured the ferromagnetic resonance of
+ferromagnetic nanowire arrays using vector-network analyzer ferromagnetic
+resonance (VNA-FMR) and analyzed the results with the micromagnetic
+simulations. We find excellent agreement between the experimental VNA-FMR
+spectra and micromagnetic simulations result for various applied magnetic
+fields. We find that the demagnetization factor for longitudinal conditions, Nz
+(Ny) increases (decreases) as decreasing the nanowire width in the
+micromagnetic simulations. For the transverse magnetic field, Nz (Ny) increases
+(decreases) as increasing the nanowire width. We also find that the Gilbert
+damping constant increases from 0.018 to 0.051 as the increasing nanowire width
+for the transverse case, while it is almost constant as 0.021 for the
+longitudinal case.",1509.01807v1
+2016-03-25,Large spin pumping effect in antisymmetric precession of Ni$_{79}$Fe$_{21}$/Ru/Ni$_{79}$Fe$_{21}$,"In magnetic trilayer structures, a contribution to the Gilbert damping of
+ferromagnetic resonance arises from spin currents pumped from one layer to
+another. This contribution has been demonstrated for layers with weakly
+coupled, separated resonances, where magnetization dynamics are excited
+predominantly in one layer and the other layer acts as a spin sink. Here we
+show that trilayer structures in which magnetizations are excited
+simultaneously, antisymmetrically, show a spin-pumping effect roughly twice as
+large. The antisymmetric (optical) mode of antiferromagnetically coupled
+Ni$_{79}$Fe$_{21}$(8nm)/Ru/Ni$_{79}$Fe$_{21}$(8nm) trilayers shows a Gilbert
+damping constant greater than that of the symmetric (acoustic) mode by an
+amount as large as the intrinsic damping of Py ($\Delta
+\alpha\simeq\textrm{0.006}$). The effect is shown equally in field-normal and
+field-parallel to film plane geometries over 3-25 GHz. The results confirm a
+prediction of the spin pumping model and have implications for the use of
+synthetic antiferromagnets (SAF)-structures in GHz devices.",1603.07977v1
+2016-10-21,Spin transport and dynamics in all-oxide perovskite La$_{2/3}$Sr$_{1/3}$MnO$_3$/SrRuO$_3$ bilayers probed by ferromagnetic resonance,"Thin films of perovskite oxides offer the possibility of combining emerging
+concepts of strongly correlated electron phenomena and spin current in magnetic
+devices. However, spin transport and magnetization dynamics in these complex
+oxide materials are not well understood. Here, we experimentally quantify spin
+transport parameters and magnetization damping in epitaxial perovskite
+ferromagnet/paramagnet bilayers of La$_{2/3}$Sr$_{1/3}$MnO$_3$/SrRuO$_3$
+(LSMO/SRO) by broadband ferromagnetic resonance spectroscopy. From the SRO
+thickness dependence of Gilbert damping, we estimate a short spin diffusion
+length of $\lesssim$1 nm in SRO and an interfacial spin-mixing conductance
+comparable to other ferromagnet/paramagnetic-metal bilayers. Moreover, we find
+that anisotropic non-Gilbert damping due to two-magnon scattering also
+increases with the addition of SRO. Our results demonstrate LSMO/SRO as a
+spin-source/spin-sink system that may be a foundation for examining
+spin-current transport in various perovskite heterostructures.",1610.06661v1
+2019-02-12,Ultra-low damping in lift-off structured yttrium iron garnet thin films,"We show that using maskless photolithography and the lift-off technique,
+patterned yttrium iron garnet thin films possessing ultra-low Gilbert damping
+can be accomplished. The films of 70 nm thickness were grown on (001)-oriented
+gadolinium gallium garnet by means of pulsed laser deposition, and they exhibit
+high crystalline quality, low surface roughness, and the effective
+magnetization of 127 emu/cm3. The Gilbert damping parameter is as low as
+5x10-4. The obtained structures have well-defined sharp edges which along with
+good structural and magnetic film properties pave a path in the fabrication of
+high-quality magnonic circuits and oxide-based spintronic devices.",1902.04605v1
+2019-02-20,CoFeB/MgO/CoFeB structures with orthogonal easy axes: perpendicular anisotropy and damping,"We report on the Gilbert damping parameter $\alpha$, the effective
+magnetization $4\pi M_{eff}$, and the asymmetry of the $g$-factor in
+bottom-CoFeB(0.93~nm)/MgO(0.90--1.25~nm)/CoFeB(1.31~nm)-top as-deposited
+systems.
+  Magnetization of CoFeB layers exhibits a specific noncollinear configuration
+with orthogonal easy axes and with $4\pi M_{eff}$ values of $+2.2$ kG and
+$-2.3$ kG for the bottom and top layers, respectively. We show that $4\pi
+M_{eff}$ depends on the asymmetry $g_\perp - g_\parallel$ of the $g$-factor
+measured in the perpendicular and the in-plane directions revealing a highly
+nonlinear relationship. In contrast, the Gilbert damping is practically the
+same for both layers. Annealing of the films results in collinear easy axes
+perpendicular to the plane for both layers. However, the linewidth is strongly
+increased due to enhanced inhomogeneous broadening.",1902.07563v1
+2021-06-28,Stability of a Magnetically Levitated Nanomagnet in Vacuum: Effects of Gas and Magnetization Damping,"In the absence of dissipation a non-rotating magnetic nanoparticle can be
+stably levitated in a static magnetic field as a consequence of the spin origin
+of its magnetization. Here we study the effects of dissipation on the stability
+of the system, considering the interaction with the background gas and the
+intrinsic Gilbert damping of magnetization dynamics. At large applied magnetic
+fields we identify magnetization switching induced by Gilbert damping as the
+key limiting factor for stable levitation. At low applied magnetic fields and
+for small particle dimensions magnetization switching is prevented due to the
+strong coupling of rotation and magnetization dynamics, and the stability is
+mainly limited by the gas-induced dissipation. In the latter case, high vacuum
+should be sufficient to extend stable levitation over experimentally relevant
+timescales. Our results demonstrate the possibility to experimentally observe
+the phenomenon of quantum spin stabilized magnetic levitation.",2106.14858v3
+2021-10-31,Thermally induced all-optical ferromagnetic resonance in thin YIG films,"All-optical ferromagnetic resonance (AO-FMR) is a powerful tool for local
+detection of micromagnetic parameters, such as magnetic anisotropy, Gilbert
+damping or spin stiffness. In this work we demonstrate that the AO-FMR method
+can be used in thin films of Yttrium Iron Garnet (YIG) if a metallic capping
+layer (Au, Pt) is deposited on top of the film. Magnetization precession is
+triggered by heating of the metallic layer with femtosecond laser pulses. The
+heating modifies the magneto-crystalline anisotropy of the YIG film and shifts
+the quasi-equilibrium orientation of magnetization, which results in
+precessional magnetization dynamics. The laser-induced magnetization precession
+corresponds to a uniform (Kittel) magnon mode, with the precession frequency
+determined by the magnetic anisotropy of the material as well as the external
+magnetic field, and the damping time set by a Gilbert damping parameter. The
+AO-FMR method thus enables measuring local magnetic properties, with spatial
+resolution given only by the laser spot size.",2111.00586v1
+2024-01-01,Calculation of Gilbert damping and magnetic moment of inertia using torque-torque correlation model within ab initio Wannier framework,"Magnetization dynamics in magnetic materials are well described by the
+modified semiclassical Landau-Lifshitz-Gilbert (LLG) equation, which includes
+the magnetic damping $\alpha$ and the magnetic moment of inertia $\mathrm{I}$
+tensors as key parameters. Both parameters are material-specific and physically
+represent the time scales of damping of precession and nutation in
+magnetization dynamics. $\alpha$ and $\mathrm{I}$ can be calculated quantum
+mechanically within the framework of the torque-torque correlation model. The
+quantities required for the calculation are torque matrix elements, the real
+and imaginary parts of the Green's function and its derivatives. Here, we
+calculate these parameters for the elemental magnets such as Fe, Co and Ni in
+an ab initio framework using density functional theory and Wannier functions.
+We also propose a method to calculate the torque matrix elements within the
+Wannier framework. We demonstrate the effectiveness of the method by comparing
+it with the experiments and the previous ab initio and empirical studies and
+show its potential to improve our understanding of spin dynamics and to
+facilitate the design of spintronic devices.",2401.00714v1
+2023-08-18,Large thermo-spin effects in Heusler alloy based spin-gapless semiconductor thin films,"Recently, Heusler alloys-based spin gapless semiconductors (SGSs) with high
+Curie temperature (TC) and sizeable spin polarization have emerged as potential
+candidates for tunable spintronic applications. We report comprehensive
+investigation of the temperature dependent ANE and intrinsic longitudinal spin
+Seebeck effect (LSSE) in CoFeCrGa thin films grown on MgO substrates. Our
+findings show the anomalous Nernst coefficient for the MgO/CoFeCrGa (95 nm)
+film is $\cong 1.86$ micro V/K at room temperature which is nearly two orders
+of magnitude higher than that of the bulk polycrystalline sample of CoFeCrGa (=
+0.018 micro V/K) but comparable to that of the magnetic Weyl semimetal Co2MnGa
+thin film (2-3 micro V/K). Furthermore, the LSSE coefficient for our
+MgO/CoFeCrGa(95nm)/Pt(5nm) heterostructure is $\cong 20.5$ $\mu$V/K/$\Omega$ at
+room temperature which is twice larger than that of the half-metallic
+ferromagnetic La$_{0.7}$Sr$_{0.3}$MnO$_3$ thin films ($\cong$ 20.5
+$\mu$V/K/$\Omega$). We show that both ANE and LSSE coefficients follow
+identical temperature dependences and exhibit a maximum at $\cong$ 225 K which
+is understood as the combined effects of inelastic magnon scatterings and
+reduced magnon population at low temperatures. Our analyses not only indicate
+that the extrinsic skew scattering is the dominating mechanism for ANE in these
+films but also provide critical insights into the functional form of the
+observed temperature dependent LSSE at low temperatures. Furthermore, by
+employing radio frequency transverse susceptibility and broadband ferromagnetic
+resonance in combination with the LSSE measurements, we establish a correlation
+among the observed LSSE signal, magnetic anisotropy and Gilbert damping of the
+CoFeCrGa thin films, which will be beneficial for fabricating tunable and
+highly efficient Heusler alloys based spincaloritronic nanodevices.",2308.09843v1
+2017-12-20,Unifying ultrafast demagnetization and intrinsic Gilbert damping in Co/Ni bilayers with electronic relaxation near the Fermi surface,"The ability to controllably manipulate the laser-induced ultrafast magnetic
+dynamics is a prerequisite for future high speed spintronic devices. The
+optimization of devices requires the controllability of the ultrafast
+demagnetization time, , and intrinsic Gilbert damping, . In previous attempts
+to establish the relationship between and , the rare-earth doping of a
+permalloy film with two different demagnetization mechanism is not a suitable
+candidate. Here, we choose Co/Ni bilayers to investigate the relations between
+and by means of time-resolved magneto-optical Kerr effect (TRMOKE) via
+adjusting the thickness of the Ni layers, and obtain an approximately
+proportional relation between these two parameters. The remarkable agreement
+between TRMOKE experiment and the prediction of breathing Fermi-surface model
+confirms that a large Elliott-Yafet spin-mixing parameter is relevant to the
+strong spin-orbital coupling at the Co/Ni interface. More importantly, a
+proportional relation between and in such metallic films or heterostructures
+with electronic relaxation near Fermi surface suggests the local spin-flip
+scattering domains the mechanism of ultrafast demagnetization, otherwise the
+spin-current mechanism domains. It is an effective method to distinguish the
+dominant contributions to ultrafast magnetic quenching in metallic
+heterostructures by investigating both the ultrafast demagnetization time and
+Gilbert damping simultaneously. Our work can open a novel avenue to manipulate
+the magnitude and efficiency of Terahertz emission in metallic heterostructures
+such as the perpendicular magnetic anisotropic Ta/Pt/Co/Ni/Pt/Ta multilayers,
+and then it has an immediate implication of the design of high frequency
+spintronic devices.",1712.07323v1
+2015-06-16,Fast energy decay for wave equations with variable damping coefficients in the 1-D half line,"We derive fast decay estimates of the total energy for wave equations with
+localized variable damping coefficients, which are dealt with in the one
+dimensional half line $(0,\infty)$. The variable damping coefficient vanishes
+near the boundary $x = 0$, and is effective critically near spatial infinity $x
+= \infty$.",1506.04851v1
+2008-05-22,Intrinsic and non-local Gilbert damping in polycrystalline nickel studied by Ti:Sapphire laser fs spectroscopy,"The use of femtosecond laser pulses generated by a Ti:Sapphire laser system
+allows us to gain an insight into the magnetization dynamics on time scales
+from sub-picosecond up to 1 ns directly in the time domain. This experimental
+technique is used to excite a polycrystalline nickel (Ni) film optically and
+probe the dynamics afterwards. Different spin wave modes (the Kittel mode,
+perpendicular standing spin-wave modes (PSSW) and dipolar spin-wave modes
+(Damon-Eshbach modes)) are identified as the Ni thickness is increased. The
+Kittel mode allows determination of the Gilbert damping parameter alpha
+extracted from the magnetization relaxation time tau_alpha. The non-local
+damping by spin currents emitted into a non-magnetic metallic layer of vanadium
+(V), palladium (Pd) and the rare earth dysprosium (Dy) are studied for
+wedge-shaped Ni films 1 nm-30 nm. The damping parameter increases from
+alpha=0.045 intrinsic for nickel to alpha>0.10 for the heavy materials, such as
+Pd and Dy, for the thinnest Ni films below 10 nm thickness. Also, for the
+thinnest reference Ni film thickness, an increased magnetic damping below 4 nm
+is observed. The origin of this increase is discussed within the framework of
+line broadening by locally different precessional frequencies within the laser
+spot region.",0805.3495v1
+2015-06-18,The absence of intraband scattering in a consistent theory of Gilbert damping in metallic ferromagnets,"Damping of magnetization dynamics in a ferromagnetic metal is usually
+characterized by the Gilbert parameter alpha. Recent calculations of this
+quantity, using a formula due to Kambersky, find that it is infinite for a
+perfect crystal owing to an intraband scattering term which is of third order
+in the spin-orbit parameter xi This surprising result conflicts with recent
+work by Costa and Muniz who study damping numerically by direct calculation of
+the dynamical transverse spin susceptibility in the presence of spin-orbit
+coupling. We resolve this inconsistency by following the Costa-Muniz approach
+for a slightly simplified model where it is possible to calculate alpha
+analytically. We show that to second order in the spin-orbit parameter xi one
+retrieves the Kambersky result for alpha, but to higher order one does not
+obtain any divergent intraband terms. The present work goes beyond that of
+Costa and Muniz by pointing out the necessity of including the effect of
+long-range Coulomb interaction in calculating damping for large xi. A direct
+derivation of the Kambersky formula is given which shows clearly the
+restriction of its validity to second order in xi so that no intraband
+scattering terms appear. This restriction has an important effect on the
+damping over a substantial range of impurity content and temperature. The
+experimental situation is discussed.",1506.05622v2
+2020-02-07,"Engineering Co$_2$MnAl$_x$Si$_{1-x}$ Heusler compounds as a model system to correlate spin polarization, intrinsic Gilbert damping and ultrafast demagnetization","Engineering of magnetic materials for developing better spintronic
+applications relies on the control of two key parameters: the spin polarization
+and the Gilbert damping responsible for the spin angular momentum dissipation.
+Both of them are expected to affect the ultrafast magnetization dynamics
+occurring on the femtosecond time scale. Here, we use engineered Co2MnAlxSi1-x
+Heusler compounds to adjust the degree of spin polarization P from 60 to 100%
+and investigate how it correlates with the damping. We demonstrate
+experimentally that the damping decreases when increasing the spin polarization
+from 1.1 10-3 for Co2MnAl with 63% spin polarization to an ultra-low value of
+4.10-4 for the half-metal magnet Co2MnSi. This allows us investigating the
+relation between these two parameters and the ultrafast demagnetization time
+characterizing the loss of magnetization occurring after femtosecond laser
+pulse excitation. The demagnetization time is observed to be inversely
+proportional to 1-P and as a consequence to the magnetic damping, which can be
+attributed to the similarity of the spin angular momentum dissipation processes
+responsible for these two effects. Altogether, our high quality Heusler
+compounds allow controlling the band structure and therefore the channel for
+spin angular momentum dissipation.",2002.02686v1
+2006-08-22,Simulation of stress-impedance effects in low magnetostrictive films,"A theoretical study of stress-impedance effect based on the solution of
+Landau-Lifsitz-Gilbert equation has been carried out. The results show that
+stress impedance effects depend largely on several extrinsic (external bias
+field, external frequency) and intrinsic (orientation and magnitude of uniaxial
+anisotropy, damping) parameters.",0608488v1
+2017-03-09,Material developments and domain wall based nanosecond-scale switching process in perpendicularly magnetized STT-MRAM cells,"We investigate the Gilbert damping and the magnetization switching of
+perpendicularly magnetized FeCoB-based free layers embedded in tunnel junctions
+adequate for spin-torque operated memories. We study the influence of the boron
+content in MgO / FeCoB /Ta systems alloys on their Gilbert damping after
+crystallization annealing. Increasing the boron content from 20 to 30\%
+increases the crystallization temperature, thereby postponing the onset of
+elemental diffusion within the free layer. This reduction of the interdiffusion
+of the Ta atoms helps maintaining the Gilbert damping at a low level of 0.009
+without any penalty on the anisotropy and the magneto-transport properties up
+to the 400$^\circ$C annealing required in CMOS back-end of line processing. In
+addition, we show that dual MgO free layers of composition
+MgO/FeCoB/Ta/FeCoB/MgO have a substantially lower damping than their
+MgO/FeCoB/Ta counterparts, reaching damping parameters as low as 0.0039 for a 3
+\r{A} thick Tantalum spacer. This confirms that the dominant channel of damping
+is the presence of Ta impurities within the FeCoB alloy. On optimized tunnel
+junctions, we then study the duration of the switching events induced by
+spin-transfer-torque. We focus on the sub-threshold thermally activated
+switching in optimal applied field conditions. From the electrical signatures
+of the switching, we infer that once the nucleation has occurred, the reversal
+proceeds by a domain wall sweeping though the device at a few 10 m/s. The
+smaller the device, the faster its switching. We present an analytical model to
+account for our findings. The domain wall velocity is predicted to scale
+linearly with the current for devices much larger than the wall width. The wall
+velocity depends on the Bloch domain wall width, such that the devices with the
+lowest exchange stiffness will be the ones that host the domain walls with the
+slowest mobilities.",1703.03198v3
+2018-07-31,"Comparative study of methodologies to compute the intrinsic Gilbert damping: interrelations, validity and physical consequences","Relaxation effects are of primary importance in the description of magnetic
+excitations, leading to a myriad of methods addressing the phenomenological
+damping parameters. In this work, we consider several well-established forms of
+calculating the intrinsic Gilbert damping within a unified theoretical
+framework, mapping out their connections and the approximations required to
+derive each formula. This scheme enables a direct comparison of the different
+methods on the same footing and a consistent evaluation of their range of
+validity. Most methods lead to very similar results for the bulk ferromagnets
+Fe, Co and Ni, due to the low spin-orbit interaction strength and the absence
+of the spin pumping mechanism. The effects of inhomogeneities, temperature and
+other sources of finite electronic lifetime are often accounted for by an
+empirical broadening of the electronic energy levels. We show that the
+contribution to the damping introduced by this broadening is additive, and so
+can be extracted by comparing the results of the calculations performed with
+and without spin-orbit interaction. Starting from simulated ferromagnetic
+resonance spectra based on the underlying electronic structure, we
+unambiguously demonstrate that the damping parameter obtained within the
+constant broadening approximation diverges for three-dimensional bulk magnets
+in the clean limit, while it remains finite for monolayers. Our work puts into
+perspective the several methods available to describe and compute the Gilbert
+damping, building a solid foundation for future investigations of magnetic
+relaxation effects in any kind of material.",1807.11808v3
+2002-07-30,Microscopic relaxation mechanisms and linear magnetization dynamics,"Linear magnetization dynamics in the presense of a thermal bath is analyzed
+for two general classes of microscopic damping mechanisms. The resulting
+stochastic differential equations are always in the form of a damped harmonic
+oscillator driven by a thermal field. The damping term contains both the
+interaction mechanisms and the symmetry of the magnetic system. Back
+transformation from the oscillator coordinates to the magnetization variables
+results in a macroscopic tensor form of damping that reflects the system
+anisotropy. Scalar Landau-Lifshitz-Gilbert damping term is valid only for
+systems with axial symmetry. Analysis of FMR linewith measurements versus
+frequency, temperature, and film thickness in NiFe films shows good agreement
+with a combination of slow-relaxing impurity and magnon-electron confluence
+processes.",0207721v1
+2014-05-09,Magnetization dynamics and damping due to electron-phonon scattering in a ferrimagnetic exchange model,"We present a microscopic calculation of magnetization damping for a magnetic
+""toy model."" The magnetic system consists of itinerant carriers coupled
+antiferromagnetically to a dispersionless band of localized spins, and the
+magnetization damping is due to coupling of the itinerant carriers to a phonon
+bath in the presence of spin-orbit coupling. Using a mean-field approximation
+for the kinetic exchange model and assuming the spin-orbit coupling to be of
+the Rashba form, we derive Boltzmann scattering integrals for the distributions
+and spin coherences in the case of an antiferromagnetic exchange splitting,
+including a careful analysis of the connection between lifetime broadening and
+the magnetic gap. For the Elliott-Yafet type itinerant spin dynamics we extract
+dephasing and magnetization times T_1 and T_2 from initial conditions
+corresponding to a tilt of the magnetization vector, and draw a comparison to
+phenomenological equations such as the Landau-Lifshitz or the Gilbert damping.
+We also analyze magnetization precession and damping for this system including
+an anisotropy field and find a carrier mediated dephasing of the localized spin
+via the mean-field coupling.",1405.2347v1
+2015-11-13,Magnified Damping under Rashba Spin Orbit Coupling,"The spin orbit coupling spin torque consists of the field-like [REF: S.G. Tan
+et al., arXiv:0705.3502, (2007).] and the damping-like terms [REF: H.
+Kurebayashi et al., Nature Nanotechnology 9, 211 (2014).] that have been widely
+studied for applications in magnetic memory. We focus, in this article, not on
+the spin orbit effect producing the above spin torques, but on its magnifying
+the damping constant of all field like spin torques. As first order precession
+leads to second order damping, the Rashba constant is naturally co-opted,
+producing a magnified field-like damping effect. The Landau-Liftshitz-Gilbert
+equations are written separately for the local magnetization and the itinerant
+spin, allowing the progression of magnetization to be self-consistently locked
+to the spin.",1511.04227v1
+2022-05-13,Precession dynamics of a small magnet with non-Markovian damping: Theoretical proposal for an experiment to determine the correlation time,"Recent advances in experimental techniques have made it possible to
+manipulate and measure the magnetization dynamics on the femtosecond time scale
+which is the same order as the correlation time of the bath degrees of freedom.
+In the equations of motion of magnetization, the correlation of the bath is
+represented by the non-Markovian damping. For development of the science and
+technologies based on the ultrafast magnetization dynamics it is important to
+understand how the magnetization dynamics depend on the correlation time. It is
+also important to determine the correlation time experimentally. Here we study
+the precession dynamics of a small magnet with the non-Markovian damping.
+Extending the theoretical analysis of Miyazaki and Seki [J. Chem. Phys. 108,
+7052 (1998)] we obtain analytical expressions of the precession angular
+velocity and the effective damping constant for any values of the correlation
+time under assumption of small Gilbert damping constant. We also propose a
+possible experiment for determination of the correlation time.",2205.06399v1
+2022-10-16,Magnetic damping anisotropy in the two-dimensional van der Waals material Fe$_3$GeTe$_2$ from first principles,"Magnetization relaxation in the two-dimensional itinerant ferromagnetic van
+der Waals material Fe$_3$GeTe$_2$, below the Curie temperature, is
+fundamentally important for applications to low-dimensional spintronics
+devices. We use first-principles scattering theory to calculate the
+temperature-dependent Gilbert damping for bulk and single-layer Fe$_3$GeTe$_2$.
+The calculated damping frequency of bulk Fe$_3$GeTe$_2$ increases monotonically
+with temperature because of the dominance of resistivitylike behavior. By
+contrast, a very weak temperature dependence is found for the damping frequency
+of a single layer, which is attributed to strong surface scattering in this
+highly confined geometry. A systematic study of the damping anisotropy reveals
+that orientational anisotropy is present in both bulk and single-layer
+Fe3GeTe2. Rotational anisotropy is significant at low temperatures for both the
+bulk and a single layer and is gradually diminished by temperature-induced
+disorder. The rotational anisotropy can be significantly enhanced by up to 430%
+in gated single-layer Fe$_3$GeTe$_2$.",2210.08429v1
+2016-09-26,Relativistic theory of spin relaxation mechanisms in the Landau-Lifshitz-Gilbert equation of spin dynamics,"Starting from the Dirac-Kohn-Sham equation we derive the relativistic
+equation of motion of spin angular momentum in a magnetic solid under an
+external electromagnetic field. This equation of motion can be written in the
+form of the well-known Landau-Lifshitz-Gilbert equation for a harmonic external
+magnetic field, and leads to a more general magnetization dynamics equation for
+a general time-dependent magnetic field. In both cases with an electronic
+spin-relaxation term which stems from the spin-orbit interaction. We thus
+rigorously derive, from fundamental principles, a general expression for the
+anisotropic damping tensor which is shown to contain an isotropic Gilbert
+contribution as well as an anisotropic Ising-like and a chiral,
+Dzyaloshinskii-Moriya-like contribution. The expression for the spin relaxation
+tensor comprises furthermore both electronic interband and intraband
+transitions. We also show that when the externally applied electromagnetic
+field possesses spin angular momentum, this will lead to an optical spin torque
+exerted on the spin moment.",1609.07901v1
+2023-08-07,$\textit{In situ}$ electric-field control of ferromagnetic resonance in the low-loss organic-based ferrimagnet V[TCNE]$_{x\sim 2}$,"We demonstrate indirect electric-field control of ferromagnetic resonance
+(FMR) in devices that integrate the low-loss, molecule-based, room-temperature
+ferrimagnet vanadium tetracyanoethylene (V[TCNE]$_{x \sim 2}$) mechanically
+coupled to PMN-PT piezoelectric transducers. Upon straining the V[TCNE]$_x$
+films, the FMR frequency is tuned by more than 6 times the resonant linewidth
+with no change in Gilbert damping for samples with $\alpha = 6.5 \times
+10^{-5}$. We show this tuning effect is due to a strain-dependent magnetic
+anisotropy in the films and find the magnetoelastic coefficient $|\lambda_S|
+\sim (1 - 4.4)$ ppm, backed by theoretical predictions from DFT calculations
+and magnetoelastic theory. Noting the rapidly expanding application space for
+strain-tuned FMR, we define a new metric for magnetostrictive materials,
+$\textit{magnetostrictive agility}$, given by the ratio of the magnetoelastic
+coefficient to the FMR linewidth. This agility allows for a direct comparison
+between magnetostrictive materials in terms of their comparative efficacy for
+magnetoelectric applications requiring ultra-low loss magnetic resonance
+modulated by strain. With this metric, we show V[TCNE]$_x$ is competitive with
+other magnetostrictive materials including YIG and Terfenol-D. This combination
+of ultra-narrow linewidth and magnetostriction in a system that can be directly
+integrated into functional devices without requiring heterogeneous integration
+in a thin-film geometry promises unprecedented functionality for electric-field
+tuned microwave devices ranging from low-power, compact filters and circulators
+to emerging applications in quantum information science and technology.",2308.03353v1
+2002-11-22,Nonlinear microscopic relaxation of uniform magnetization precession,"Dynamic relaxation for nonlinear magnetization excitation is analyzed. For
+direct processes, such as magnon-electron scattering and two-magnon scattering,
+the relaxation rate is determined from the linear case simply by utilizing the
+magnetization oscillation frequency for nonlinear excitation. For an indirect
+process, such as slow-relaxing impurities, the analysis gives an additional
+relaxation term proportional to the excitation level. In all cases the
+effective magnetization damping is increased compared to
+Landau-Lifshitz-Gilbert damping.",0211499v1
+2005-10-11,Non-damping magnetization oscillations in a single-domain ferromagnet,"Non-damped oscillations of the magnetization vector of a ferromagnetic system
+subject to a spin polarized current and an external magnetic field are studied
+theoretically by solving the Landau-Lifshitz-Gilbert equation. It is shown that
+the frequency and amplitude of such oscillations can be controlled by means of
+an applied magnetic field and a spin current. The possibility of injection of
+the oscillating spin current into a non-magnetic system is also discussed.",0510280v1
+2007-03-27,Gauge Field Formulation of Adiabatic Spin Torques,"Previous calculation of spin torques for small-amplitude magnetization
+dynamics around a uniformly magnetized state [J. Phys. Soc. Jpn. {\bf 75}
+(2006) 113706] is extended here to the case of finite-amplitude dynamics. This
+is achieved by introducing an `` adiabatic'' spin frame for conduction
+electrons, and the associated SU(2) gauge field. In particular, the Gilbert
+damping is shown to arise from the time variation of the spin-relaxation source
+terms in this new frame, giving a new physical picture of the damping. The
+present method will allow a `` first-principle'' derivation of spin torques
+without any assumptions such as rotational symmetry in spin space.",0703705v1
+2008-05-09,"Spin dynamics in (III,Mn)V ferromagnetic semiconductors: the role of correlations","We address the role of correlations between spin and charge degrees of
+freedom on the dynamical properties of ferromagnetic systems governed by the
+magnetic exchange interaction between itinerant and localized spins. For this
+we introduce a general theory that treats quantum fluctuations beyond the
+Random Phase Approximation based on a correlation expansion of the Green's
+function equations of motion. We calculate the spin susceptibility, spin--wave
+excitation spectrum, and magnetization precession damping. We find that
+correlations strongly affect the magnitude and carrier concentration dependence
+of the spin stiffness and magnetization Gilbert damping.",0805.1320v2
+2010-01-16,Resonance Damping in Ferromagnets and Ferroelectrics,"The phenomenological equations of motion for the relaxation of ordered phases
+of magnetized and polarized crystal phases can be developed in close analogy
+with one another. For the case of magnetized systems, the driving magnetic
+field intensity toward relaxation was developed by Gilbert. For the case of
+polarized systems, the driving electric field intensity toward relaxation was
+developed by Khalatnikov. The transport times for relaxation into thermal
+equilibrium can be attributed to viscous sound wave damping via
+magnetostriction for the magnetic case and electrostriction for the
+polarization case.",1001.2845v1
+2016-05-15,Propagation of Thermally Induced Magnonic Spin Currents,"The propagation of magnons in temperature gradients is investigated within
+the framework of an atomistic spin model with the stochastic
+Landau-Lifshitz-Gilbert equation as underlying equation of motion. We analyze
+the magnon accumulation, the magnon temperature profile as well as the
+propagation length of the excited magnons. The frequency distribution of the
+generated magnons is investigated in order to derive an expression for the
+influence of the anisotropy and the damping parameter on the magnon propagation
+length. For soft ferromagnetic insulators with low damping a propagation length
+in the range of some $\mu$m can be expected for exchange driven magnons.",1605.04543v1
+2021-03-05,Universal spin wave damping in magnetic Weyl semimetals,"We analyze the decay of spin waves into Stoner excitations in magnetic Weyl
+semimetals. The lifetime of a mode is found to have a universal dependence on
+its frequency and momentum, and on a few parameters that characterize the
+relativistic Weyl spectrum. At the same time, Gilbert damping by Weyl electrons
+is absent. The decay rate of spin waves is calculated perturbatively using the
+s-d model of itinerant Weyl or Dirac electrons coupled to local moments. We
+show that many details of the Weyl spectrum, such as the momentum-space
+locations, dispersions and sizes of the Weyl Fermi pockets, can be deduced
+indirectly by probing the spin waves of local moments using inelastic neutron
+scattering.",2103.03885v1
+2023-02-17,Control of magnon-photon coupling by spin torque,"We demonstrate the influence of damping and field-like torques in the
+magnon-photon coupling process by classically integrating the generalized
+Landau-Lifshitz-Gilbert equation with RLC equation in which a phase correlation
+between dynamic magnetization and microwave current through combined Amp\`ere
+and Faraday effects are considered. We show that the gap between two hybridized
+modes can be controlled in samples with damping parameter in the order of
+$10^{-3}$ by changing the direction of the dc current density $J$ if a certain
+threshold is reached. Our results suggest that an experimental realization of
+the proposed magnon-photon coupling control mechanism is feasible in yttrium
+iron garnet/Pt hybrid structures.",2302.08910v1
+2017-03-21,Using rf voltage induced ferromagnetic resonance to study the spin-wave density of states and the Gilbert damping in perpendicularly magnetized disks,"We study how the shape of the spinwave resonance lines in rf-voltage induced
+FMR can be used to extract the spinwave density of states and the damping
+within the precessing layer in nanoscale tunnel junctions that possess
+perpendicular anisotropy. We work with a field applied along the easy axis to
+preserve the uniaxial symmetry of the system. We describe the set-up to study
+the susceptibility contributions of the spin waves in the field-frequency
+space. We then identify the maximum device size above which the spinwaves can
+no longer be studied in isolation as the linewidths of their responses make
+them overlap. The rf-voltage induced signal is the sum of two voltages that
+have comparable magnitudes: a first voltage that originates from the transverse
+susceptibility and rectification by magnetoresistance and a second voltage that
+arises from the non-linear longitudinal susceptibility and the resultant
+time-averaged change of the micromagnetic configuration. The transverse and
+longitudinal susceptibility signals have different dc bias dependences such
+that they can be separated by measuring how the device rectifies the rf voltage
+at different dc bias voltages. The transverse and longitudinal susceptibility
+signals have different lineshapes; their joint studies can yield the Gilbert
+damping of the free layer of the device with a degree of confidence that
+compares well with standard FMR. Our method is illustrated on FeCoB-based free
+layers in which the individual spin-waves can be sufficiently resolved only for
+disk diameters below 200 nm. The resonance line shapes on devices with 90 nm
+diameters are consistent with a Gilbert damping of 0.011. This damping of 0.011
+exceeds the value of 0.008 measured on the unpatterned films, which indicates
+that device-level measurements are needed for a correct evaluation of
+dissipation.",1703.07310v2
+2015-11-16,Determination of intrinsic damping of perpendicularly magnetized ultrathin films from time resolved precessional magnetization measurements,"Magnetization dynamics are strongly influenced by damping. An effective
+damping constant {\alpha}eff is often determined experimentally from the
+spectral linewidth of the free induction decay of the magnetization after the
+system is excited to its non-equilibrium state. Such an {\alpha}eff, however,
+reflects both intrinsic damping as well as inhomogeneous broadening. In this
+paper we compare measurements of the magnetization dynamics in ultrathin
+non-epitaxial films having perpendicular magnetic anisotropy using two
+different techniques, time-resolved magneto optical Kerr effect (TRMOKE) and
+hybrid optical-electrical ferromagnetic resonance (OFMR). By using an external
+magnetic field that is applied at very small angles to the film plane in the
+TRMOKE studies, we develop an explicit closed-form analytical expression for
+the TRMOKE spectral linewidth and show how this can be used to reliably extract
+the intrinsic Gilbert damping constant. The damping constant determined in this
+way is in excellent agreement with that determined from the OFMR method on the
+same samples. Our studies indicate that the asymptotic high-field approach that
+is often used in the TRMOKE method to distinguish the intrinsic damping from
+the effective damping may result in significant error, because such high
+external magnetic fields are required to make this approach valid that they are
+out of reach. The error becomes larger the lower is the intrinsic damping
+constant, and thus may account for the anomalously high damping constants that
+are often reported in TRMOKE studies. In conventional ferromagnetic resonance
+(FMR) studies, inhomogeneous contributions can be readily distinguished from
+intrinsic damping contributions from the magnetic field dependence of the FMR
+linewidth. Using the analogous approach, we show how reliable values of the
+intrinsic damping can be extracted from TRMOKE.",1511.04802v1
+2019-08-19,Spectral determinant for the damped wave equation on an interval,"We evaluate the spectral determinant for the damped wave equation on an
+interval of length $T$ with Dirichlet boundary conditions, proving that it does
+not depend on the damping. This is achieved by analysing the square of the
+damped wave operator using the general result by Burghelea, Friedlander, and
+Kappeler on the determinant for a differential operator with matrix
+coefficients.",1908.06862v1
+2020-10-12,Decays rates for Kelvin-Voigt damped wave equations II: the geometric control condition,"We study in this article decay rates for Kelvin-Voigt damped wave equations
+under a geometric control condition. We prove that when the damping coefficient
+is sufficiently smooth ($C^1$ vanishing nicely) we show that exponential decay
+follows from geometric control conditions (see~\cite{BuCh, Te12} for similar
+results under stronger assumptions on the damping function).",2010.05614v2
+2019-06-21,Unique determination of the damping coefficient in the wave equation using point source and receiver data,"In this article, we consider the inverse problems of determining the damping
+coefficient appearing in the wave equation. We prove the unique determination
+of the coefficient from the data coming from a single coincident
+source-receiver pair. Since our problem is under-determined, so some extra
+assumption on the coefficient is required to prove the uniqueness.",1906.08987v1
+2002-07-19,Gilbert Damping in Magnetic Multilayers,"We study the enhancement of the ferromagnetic relaxation rate in thin films
+due to the adjacent normal metal layers. Using linear response theory, we
+derive the dissipative torque produced by the s-d exchange interaction at the
+ferromagnet-normal metal interface. For a slow precession, the enhancement of
+Gilbert damping constant is proportional to the square of the s-d exchange
+constant times the zero-frequency limit of the frequency derivative of the
+local dynamic spin susceptibility of the normal metal at the interface.
+Electron-electron interactions increase the relaxation rate by the Stoner
+factor squared. We attribute the large anisotropic enhancements of the
+relaxation rate observed recently in multilayers containing palladium to this
+mechanism. For free electrons, the present theory compares favorably with
+recent spin-pumping result of Tserkovnyak et al. [Phys. Rev. Lett.
+\textbf{88},117601 (2002)].",0207471v1
+2002-08-06,Spin pumping and magnetization dynamics in metallic multilayers,"We study the magnetization dynamics in thin ferromagnetic films and small
+ferromagnetic particles in contact with paramagnetic conductors. A moving
+magnetization vector causes \textquotedblleft pumping\textquotedblright of
+spins into adjacent nonmagnetic layers. This spin transfer affects the
+magnetization dynamics similar to the Landau-Lifshitz-Gilbert phenomenology.
+The additional Gilbert damping is significant for small ferromagnets, when the
+nonmagnetic layers efficiently relax the injected spins, but the effect is
+reduced when a spin accumulation build-up in the normal metal opposes the spin
+pumping. The damping enhancement is governed by (and, in turn, can be used to
+measure) the mixing conductance or spin-torque parameter of the
+ferromagnet--normal-metal interface. Our theoretical findings are confirmed by
+agreement with recent experiments in a variety of multilayer systems.",0208091v2
+2005-12-29,Current-induced magnetization dynamics in disordered itinerant ferromagnets,"Current-driven magnetization dynamics in ferromagnetic metals are studied in
+a self-consistent adiabatic local-density approximation in the presence of
+spin-conserving and spin-dephasing impurity scattering. Based on a quantum
+kinetic equation, we derive Gilbert damping and spin-transfer torques entering
+the Landau-Lifshitz equation to linear order in frequency and wave vector.
+Gilbert damping and a current-driven dissipative torque scale identically and
+compete, with the result that a steady current-driven domain-wall motion is
+insensitive to spin dephasing in the limit of weak ferromagnetism. A uniform
+magnetization is found to be much more stable against spin torques in the
+itinerant than in the \textit{s}-\textit{d} model for ferromagnetism. A dynamic
+spin-transfer torque reminiscent of the spin pumping in multilayers is
+identified and shown to govern the current-induced domain-wall distortion.",0512715v4
+2006-11-22,Magnetization damping in a local-density approximation,"The linear response of itinerant transition metal ferromagnets to transverse
+magnetic fields is studied in a self-consistent adiabatic local-density
+approximation. The susceptibility is calculated from a microscopic Hamiltonian,
+including spin-conserving impurities, impurity induced spin-orbit interaction
+and magnetic impurities using the Keldysh formalism. The Gilbert damping
+constant in the Landau-Lifshitz-Gilbert equation is identified, parametrized by
+an effective transverse spin dephasing rate, and is found to be inversely
+proportional to the exchange splitting. Our result justify the phenomenological
+treatment of transverse spin dephasing in the study of current-induced
+magnetization dynamics in weak, itinerant ferromagnets by Tserkovnyak
+\textit{et al.}. We show that neglect of gradient corrections in the
+quasiclassical transport equations leads to incorrect results when the exchange
+potential becomes of the order of the Fermi energy.",0611588v1
+2007-08-03,Strong spin-orbit induced Gilbert damping and g-shift in iron-platinum nanoparticles,"The shape of ferromagnetic resonance spectra of highly dispersed, chemically
+disordered Fe_{0.2}Pt_{0.8} nanospheres is perfectly described by the solution
+of the Landau-Lifshitz-Gilbert (LLG) equation excluding effects by crystalline
+anisotropy and superparamagnetic fluctuations. Upon decreasing temperature, the
+LLG damping $\alpha(T)$ and a negative g-shift, g(T)-g_0, increase proportional
+to the particle magnetic moments determined from the Langevin analysis of the
+magnetization isotherms. These novel features are explained by the scattering
+of the $q \to 0$ magnon from an electron-hole (e/h) pair mediated by the
+spin-orbit coupling, while the sd-exchange can be ruled out. The large
+saturation values, $\alpha(0)=0.76$ and $g(0)/g_0-1=-0.37$, indicate the
+dominance of an overdamped 1 meV e/h-pair which seems to originate from the
+discrete levels of the itinerant electrons in the d_p=3 nm nanoparticles.",0708.0463v1
+2008-05-01,Chaotic Spin Dynamics of a Long Nanomagnet Driven by a Current,"We study the spin dynamics of a long nanomagnet driven by an electrical
+current. In the case of only DC current, the spin dynamics has a sophisticated
+bifurcation diagram of attractors. One type of attractors is a weak chaos. On
+the other hand, in the case of only AC current, the spin dynamics has a rather
+simple bifurcation diagram of attractors. That is, for small Gilbert damping,
+when the AC current is below a critical value, the attractor is a limit cycle;
+above the critical value, the attractor is chaotic (turbulent). For normal
+Gilbert damping, the attractor is always a limit cycle in the physically
+interesting range of the AC current. We also developed a Melnikov integral
+theory for a theoretical prediction on the occurrence of chaos. Our Melnikov
+prediction seems performing quite well in the DC case. In the AC case, our
+Melnikov prediction seems predicting transient chaos. The sustained chaotic
+attractor seems to have extra support from parametric resonance leading to a
+turbulent state.",0805.0147v1
+2010-10-08,"A unified first-principles study of Gilbert damping, spin-flip diffusion and resistivity in transition metal alloys","Using a formulation of first-principles scattering theory that includes
+disorder and spin-orbit coupling on an equal footing, we calculate the
+resistivity $\rho$, spin flip diffusion length $l_{sf}$ and the Gilbert damping
+parameter $\alpha$ for Ni$_{1-x}$Fe$_x$ substitutional alloys as a function of
+$x$. For the technologically important Ni$_{80}$Fe$_{20}$ alloy, permalloy, we
+calculate values of $\rho = 3.5 \pm 0.15$ $\mu$Ohm-cm, $l_{sf}=5.5 \pm 0.3$ nm,
+and $\alpha= 0.0046 \pm 0.0001$ compared to experimental low-temperature values
+in the range $4.2-4.8$ $\mu$Ohm-cm for $\rho$, $5.0-6.0$ nm for $l_{sf}$, and
+$0.004-0.013$ for $\alpha$ indicating that the theoretical formalism captures
+the most important contributions to these parameters.",1010.1626v3
+2011-02-22,Ab-initio calculation of the Gilbert damping parameter via linear response formalism,"A Kubo-Greenwood-like equation for the Gilbert damping parameter $\alpha$ is
+presented that is based on the linear response formalism. Its implementation
+using the fully relativistic Korringa-Kohn-Rostoker (KKR) band structure method
+in combination with Coherent Potential Approximation (CPA) alloy theory allows
+it to be applied to a wide range of situations. This is demonstrated with
+results obtained for the bcc alloy system Fe$_x$Co$_{1-x}$ as well as for a
+series of alloys of permalloy with 5d transition metals.
+  To account for the thermal displacements of atoms as a scattering mechanism,
+an alloy-analogy model is introduced. The corresponding calculations for Ni
+correctly describe the rapid change of $\alpha$ when small amounts of
+substitutional Cu are introduced.",1102.4551v1
+2012-08-07,Observation of Coherent Helimagnons and Gilbert damping in an Itinerant Magnet,"We study the magnetic excitations of itinerant helimagnets by applying
+time-resolved optical spectroscopy to Fe0.8Co0.2Si. Optically excited
+oscillations of the magnetization in the helical state are found to disperse to
+lower frequency as the applied magnetic field is increased; the fingerprint of
+collective modes unique to helimagnets, known as helimagnons. The use of
+time-resolved spectroscopy allows us to address the fundamental magnetic
+relaxation processes by directly measuring the Gilbert damping, revealing the
+versatility of spin dynamics in chiral magnets. (*These authors contributed
+equally to this work)",1208.1462v1
+2012-11-02,Dynamic Spin Injection into Chemical Vapor Deposited Graphene,"We demonstrate dynamic spin injection into chemical vapor deposition (CVD)
+grown graphene by spin pumping from permalloy (Py) layers. Ferromagnetic
+resonance measurements at room temperature reveal a strong enhancement of the
+Gilbert damping at the Py/graphene interface, exceeding that observed in even
+Py/platinum interfaces. Similar results are also shown on Co/graphene layers.
+This enhancement in the Gilbert damping is understood as the consequence of
+spin pumping at the interface driven by magnetization dynamics. Our
+observations suggest a strong enhancement of spin-orbit coupling in CVD
+graphene, in agreement with earlier spin valve measurements.",1211.0492v1
+2013-01-10,First-principles calculation of the Gilbert damping parameter via the linear response formalism with application to magnetic transition-metals and alloys,"A method for the calculations of the Gilbert damping parameter $\alpha$ is
+presented, which based on the linear response formalism, has been implemented
+within the fully relativistic Korringa-Kohn-Rostoker band structure method in
+combination with the coherent potential approximation alloy theory. To account
+for thermal displacements of atoms as a scattering mechanism, an alloy-analogy
+model is introduced. This allows the determination of $\alpha$ for various
+types of materials, such as elemental magnetic systems and ordered magnetic
+compounds at finite temperature, as well as for disordered magnetic alloys at
+$T = 0$ K and above. The effects of spin-orbit coupling, chemical and
+temperature induced structural disorder are analyzed. Calculations have been
+performed for the 3$d$ transition-metals bcc Fe, hcp Co, and fcc Ni, their
+binary alloys bcc Fe$_{1-x}$Co$_{x}$, fcc Ni$_{1-x}$Fe$_x$, fcc
+Ni$_{1-x}$Co$_x$ and bcc Fe$_{1-x}$V$_{x}$, and for 5d impurities in
+transition-metal alloys. All results are in satisfying agreement with
+experiment.",1301.2114v1
+2014-01-24,Wavenumber-dependent Gilbert damping in metallic ferromagnets,"New terms to the dynamical equation of magnetization motion, associated with
+spin transport, have been reported over the past several years. Each newly
+identified term is thought to possess both a real and an imaginary effective
+field leading to fieldlike and dampinglike torques on magnetization. Here we
+show that three metallic ferromagnets possess an imaginary effective-field term
+which mirrors the well-known real effective-field term associated with exchange
+in spin waves. Using perpendicular standing spin wave resonance between 2-26
+GHz, we evaluate the magnitude of the finite-wavenumber ($k$) dependent Gilbert
+damping $\alpha$ in three typical device ferromagnets, Ni$_{79}$Fe$_{21}$, Co,
+and Co$_{40}$Fe$_{40}$B$_{20}$, and demonstrate for the first time the presence
+of a $k^2$ term as $\Delta\alpha=\Delta\alpha_0+A_{k}\cdot k^2$ in all three
+metals. We interpret the new term as the continuum analog of spin pumping,
+predicted recently, and show that its magnitude, $A_{k}$=0.07-0.1 nm$^2$, is
+consistent with transverse spin relaxation lengths as measured by conventional
+(interlayer) spin pumping.",1401.6467v2
+2014-12-11,Deviation From the Landau-Lifshitz-Gilbert equation in the Inertial regime of the Magnetization,"We investigate in details the inertial dynamics of a uniform magnetization in
+the ferromagnetic resonance (FMR) context. Analytical predictions and numerical
+simulations of the complete equations within the Inertial
+Landau-Lifshitz-Gilbert (ILLG) model are presented. In addition to the usual
+precession resonance, the inertial model gives a second resonance peak
+associated to the nutation dynamics provided that the damping is not too large.
+The analytical resolution of the equations of motion yields both the precession
+and nutation angular frequencies. They are function of the inertial dynamics
+characteristic time $\tau$, the dimensionless damping $\alpha$ and the static
+magnetic field $H$. A scaling function with respect to $\alpha\tau\gamma H$ is
+found for the nutation angular frequency, also valid for the precession angular
+frequency when $\alpha\tau\gamma H\gg 1$. Beyond the direct measurement of the
+nutation resonance peak, we show that the inertial dynamics of the
+magnetization has measurable effects on both the width and the angular
+frequency of the precession resonance peak when varying the applied static
+field. These predictions could be used to experimentally identify the inertial
+dynamics of the magnetization proposed in the ILLG model.",1412.3783v1
+2015-08-04,A Critical Analysis of the Feasibility of Pure Strain-Actuated Giant Magnetostrictive Nanoscale Memories,"Concepts for memories based on the manipulation of giant magnetostrictive
+nanomagnets by stress pulses have garnered recent attention due to their
+potential for ultra-low energy operation in the high storage density limit.
+Here we discuss the feasibility of making such memories in light of the fact
+that the Gilbert damping of such materials is typically quite high. We report
+the results of numerical simulations for several classes of toggle precessional
+and non-toggle dissipative magnetoelastic switching modes. Material candidates
+for each of the several classes are analyzed and forms for the anisotropy
+energy density and ranges of material parameters appropriate for each material
+class are employed. Our study indicates that the Gilbert damping as well as the
+anisotropy and demagnetization energies are all crucial for determining the
+feasibility of magnetoelastic toggle-mode precessional switching schemes. The
+roles of thermal stability and thermal fluctuations for stress-pulse switching
+of giant magnetostrictive nanomagnets are also discussed in detail and are
+shown to be important in the viability, design, and footprint of
+magnetostrictive switching schemes.",1508.00629v2
+2015-12-16,Parity-time symmetry breaking in magnetic systems,"The understanding of out-of-equilibrium physics, especially dynamic
+instabilities and dynamic phase transitions, is one of the major challenges of
+contemporary science, spanning the broadest wealth of research areas that range
+from quantum optics to living organisms. Focusing on nonequilibrium dynamics of
+an open dissipative spin system, we introduce a non-Hermitian Hamiltonian
+approach, in which non-Hermiticity reflects dissipation and deviation from
+equilibrium. The imaginary part of the proposed spin Hamiltonian describes the
+effects of Gilbert damping and applied Slonczewski spin-transfer torque. In the
+classical limit, our approach reproduces Landau-Lifshitz-Gilbert-Slonczewski
+dynamics of a large macrospin. We reveal the spin-transfer torque-driven
+parity-time symmetry-breaking phase transition corresponding to a transition
+from precessional to exponentially damped spin dynamics. Micromagnetic
+simulations for nanoscale ferromagnetic disks demonstrate the predicted effect.
+Our findings can pave the way to a general quantitative description of
+out-of-equilibrium phase transitions driven by spontaneous parity-time symmetry
+breaking.",1512.05408v2
+2017-01-11,The Cauchy problem for the Landau-Lifshitz-Gilbert equation in BMO and self-similar solutions,"We prove a global well-posedness result for the Landau-Lifshitz equation with
+Gilbert damping provided that the BMO semi-norm of the initial data is small.
+As a consequence, we deduce the existence of self-similar solutions in any
+dimension. In the one-dimensional case, we characterize the self-similar
+solutions associated with an initial data given by some ($\mathbb{S}^2$-valued)
+step function and establish their stability. We also show the existence of
+multiple solutions if the damping is strong enough. Our arguments rely on the
+study of a dissipative quasilinear Schr\""odinger obtained via the stereographic
+projection and techniques introduced by Koch and Tataru.",1701.03083v2
+2017-01-27,Structural scale $q-$derivative and the LLG-Equation in a scenario with fractionality,"In the present contribution, we study the Landau-Lifshitz-Gilbert equation
+with two versions of structural derivatives recently proposed: the scale
+$q-$derivative in the non-extensive statistical mechanics and the axiomatic
+metric derivative, which presents Mittag-Leffler functions as eigenfunctions.
+The use of structural derivatives aims to take into account long-range forces,
+possible non-manifest or hidden interactions and the dimensionality of space.
+Having this purpose in mind, we build up an evolution operator and a deformed
+version of the LLG equation. Damping in the oscillations naturally show up
+without an explicit Gilbert damping term.",1701.08076v2
+2018-10-17,Perpendicularly magnetized YIG films with small Gilbert damping constant and anomalous spin transport properties,"The Y3Fe5O12 (YIG) films with perpendicular magnetic anisotropy (PMA) have
+recently attracted a great deal of attention for spintronics applications.
+Here, we report the induced PMA in the ultrathin YIG films grown on
+(Gd2.6Ca0.4)(Ga4.1Mg0.25Zr0.65)O12 (SGGG) substrates by epitaxial strain
+without preprocessing. Reciprocal space mapping shows that the films are
+lattice-matched to the substrates without strain relaxation. Through
+ferromagnetic resonance and polarized neutron reflectometry measurements, we
+find that these YIG films have ultra-low Gilbert damping constant with a
+magnetic dead layer as thin as about 0.3 nm at the YIG/SGGG interfaces.
+Moreover, the transport behavior of the Pt/YIG/SGGG films reveals an
+enhancement of spin mixing conductance and a large non-monotonic magnetic field
+dependence of anomalous Hall effect as compared with the Pt/YIG/Gd3Ga5O12 (GGG)
+films. The non-monotonic anomalous Hall signal is extracted in the temperature
+range from 150 to 350 K, which has been ascribed to the possible non-collinear
+magnetic order at the Pt/YIG interface induced by uniaxial strain.",1810.07384v2
+2019-03-07,Current-induced motion of twisted skyrmions,"Twisted skyrmions, whose helicity angles are different from that of Bloch
+skyrmions and N\'eel skyrmions, have already been demonstrated in experiments
+recently. In this work, we first contrast the magnetic structure and origin of
+the twisted skyrmion with other three types of skyrmion including Bloch
+skyrmion, N\'eel skyrmion and antiskyrmion. Following, we investigate the
+dynamics of twisted skyrmions driven by the spin transfer toque (STT) and the
+spin Hall effect (SHE) by using micromagnetic simulations. It is found that the
+spin Hall angle of the twisted skyrmion is related to the dissipative force
+tensor and the Gilbert damping both for the motions induced by the STT and the
+SHE, especially for the SHE induced motion, the skyrmion Hall angle depends
+substantially on the skyrmion helicity. At last, we demonstrate that the
+trajectory of the twisted skyrmion can be controlled in a two dimensional plane
+with a Gilbert damping gradient. Our results provide the understanding of
+current-induced motion of twisted skyrmions, which may contribute to the
+applications of skyrmion-based racetrack memories.",1903.02812v1
+2019-07-03,Anisotropy of spin-transfer torques and Gilbert damping induced by Rashba coupling,"Spin-transfer torques (STT), Gilbert damping (GD), and effective spin
+renormalization (ESR) are investigated microscopically in a 2D Rashba
+ferromagnet with spin-independent Gaussian white-noise disorder. Rashba
+spin-orbit coupling induced anisotropy of these phenomena is thoroughly
+analysed. For the case of two partly filled spin subbands, a remarkable
+relation between the anisotropic STT, GD, and ESR is established. In the
+absence of magnetic field and other torques on magnetization, this relation
+corresponds to a current-induced motion of a magnetic texture with the
+classical drift velocity of conduction electrons. Finally, we compute spin
+susceptibility of the system and generalize the notion of spin-polarized
+current.",1907.02041v3
+2021-11-05,Giant oscillatory Gilbert damping in superconductor/ferromagnet/superconductor junctions,"Interfaces between materials with differently ordered phases present unique
+opportunities for exotic physical properties, especially the interplay between
+ferromagnetism and superconductivity in the ferromagnet/superconductor
+heterostructures. The investigation of zero- and pi-junctions has been of
+particular interest for both fundamental physical science and emerging
+technologies. Here, we report the experimental observation of giant oscillatory
+Gilbert damping in the superconducting Nb/NiFe/Nb junctions with respect to the
+NiFe thickness. This observation suggests an unconventional spin pumping and
+relaxation via zero-energy Andreev bound states that exist only in the
+Nb/NiFe/Nb pi-junctions, but not in the Nb/NiFe/Nb zero-junctions. Our findings
+could be important for further exploring the exotic physical properties of
+ferromagnet/superconductor heterostructures, and potential applications of
+ferromagnet pi-junctions in quantum computing, such as half-quantum flux
+qubits.",2111.03233v1
+2022-11-14,Magnetization Dynamics in Synthetic Antiferromagnets with Perpendicular Magnetic Anisotropy,"Understanding the rich physics of magnetization dynamics in perpendicular
+synthetic antiferromagnets (p-SAFs) is crucial for developing next-generation
+spintronic devices. In this work, we systematically investigate the
+magnetization dynamics in p-SAFs combining time-resolved magneto-optical Kerr
+effect (TR-MOKE) measurements with theoretical modeling. These model analyses,
+based on a Landau-Lifshitz-Gilbert approach incorporating exchange coupling,
+provide details about the magnetization dynamic characteristics including the
+amplitudes, directions, and phases of the precession of p-SAFs under varying
+magnetic fields. These model-predicted characteristics are in excellent
+quantitative agreement with TR-MOKE measurements on an asymmetric p-SAF. We
+further reveal the damping mechanisms of two procession modes co-existing in
+the p-SAF and successfully identify individual contributions from different
+sources, including Gilbert damping of each ferromagnetic layer, spin pumping,
+and inhomogeneous broadening. Such a comprehensive understanding of
+magnetization dynamics in p-SAFs, obtained by integrating high-fidelity TR-MOKE
+measurements and theoretical modeling, can guide the design of p-SAF-based
+architectures for spintronic applications.",2211.07744v2
+2023-05-17,Material Parameters for Faster Ballistic Switching of an In-plane Magnetized Nanomagnet,"High-speed magnetization switching of a nanomagnet is necessary for faster
+information processing. The ballistic switching by a pulsed magnetic filed is a
+promising candidate for the high-speed switching. It is known that the
+switching speed of the ballistic switching can be increased by increasing the
+magnitude of the pulsed magnetic field. However it is difficult to generate a
+strong and short magnetic field pulse in a small device. Here we explore
+another direction to achieve the high-speed ballistic switching by designing
+material parameters such as anisotropy constant, saturation magnetization, and
+the Gilbert damping constant. We perform the macrospin simulations for the
+ballistic switching of in-plane magnetized nano magnets with varying material
+parameters. The results are analyzed based on the switching dynamics on the
+energy density contour. We show that the pulse width required for the ballistic
+switching can be reduced by increasing the magnetic anisotropy constant or by
+decreasing the saturation magnetization. We also show that there exists an
+optimal value of the Gilbert damping constant that minimizes the pulse width
+required for the ballistic switching.",2305.10111v1
+2023-05-23,Current-driven motion of magnetic topological defects in ferromagnetic superconductors,"Recent years have seen a number of instances where magnetism and
+superconductivity intrinsically coexist. Our focus is on the case where
+spin-triplet superconductivity arises out of ferromagnetism, and we make a
+hydrodynamic analysis of the effect of a charge supercurrent on magnetic
+topological defects like domain walls and merons. We find that the emergent
+electromagnetic field that arises out of the superconducting order parameter
+provides a description for not only the physical quantities such as the local
+energy flux density and the interaction between current and defects but also
+the energy dissipation through magnetic dynamics of the Gilbert damping, which
+becomes more prominent compared to the normal state as superconductivity
+attenuates the energy dissipation through the charge sector. In particular, we
+reveal that the current-induced dynamics of domain walls and merons in the
+presence of the Gilbert damping give rise to the nonsingular $4\pi$ and $2\pi$
+phase slips, respectively, revealing the intertwined dynamics of spin and
+charge degrees of freedom in ferromagnetic superconductors.",2305.13564v1
+2023-07-03,Magnetic lump motion in saturated ferromagnetic films,"In this paper, we study in detail the nonlinear propagation of magnetic
+soliton in a ferromagnetic film. The sample is magnetized to saturation by an
+external field perpendicular to film plane. A new generalized (2+1)-dimensional
+short-wave asymptotic model is derived. The bilinear-like forms of this
+equation are constructed, and exact magnetic line soliton solutions are
+exhibited. It is observed that a series of stable lumps can be generated by an
+unstable magnetic soliton under Gaussian disturbance. Such magnetic lumps are
+highly stable and can maintain their shapes and velocities during evolution or
+collision. The interaction between lump and magnetic soliton, as well as
+interaction between two lumps, are numerically investigated. We further discuss
+the nonlinear motion of lumps in ferrites with Gilbert-damping and
+inhomogeneous exchange effects. The results show that the Gilbert-damping
+effects make the amplitude and velocity of the magnetic lump decay
+exponentially during propagation. And the shock waves are generated from a lump
+when quenching the strength of inhomogeneous exchange.",2307.00903v1
+2005-03-24,Fast magnetization switching of Stoner particles: A nonlinear dynamics picture,"The magnetization reversal of Stoner particles is investigated from the point
+of view of nonlinear dynamics within the Landau-Lifshitz-Gilbert formulation.
+The following results are obtained. 1) We clarify that the so-called
+Stoner-Wohlfarth (SW) limit becomes exact when damping constant is infinitely
+large. Under the limit, the magnetization moves along the steepest energy
+descent path. The minimal switching field is the one at which there is only one
+stable fixed point in the system. 2) For a given magnetic anisotropy, there is
+a critical value for the damping constant, above which the minimal switching
+field is the same as that of the SW-limit. 3) We illustrate how fixed points
+and their basins change under a field along different directions. This change
+explains well why a non-parallel field gives a smaller minimal switching field
+and a short switching time. 4) The field of a ballistic magnetization reversal
+should be along certain direction window in the presence of energy dissipation.
+The width of the window depends on both of the damping constant and the
+magnetic anisotropy. The upper and lower bounds of the direction window
+increase with the damping constant. The window width oscillates with the
+damping constant for a given magnetic anisotropy. It is zero for both zero and
+infinite damping. Thus, the perpendicular field configuration widely employed
+in the current experiments is not the best one since the damping constant in a
+real system is far from zero.",0503594v1
+2022-03-03,Stability results of locally coupled wave equations with local Kelvin-Voigt damping: Cases when the supports of damping and coupling coefficients are disjoint,"In this paper, we study the direct/indirect stability of locally coupled wave
+equations with local Kelvin-Voigt dampings/damping and by assuming that the
+supports of the dampings and the coupling coefficients are disjoint. First, we
+prove the well-posedness, strong stability, and polynomial stability for some
+one dimensional coupled systems. Moreover, under some geometric control
+condition, we prove the well-posedness and strong stability in the
+multi-dimensional case.",2203.01632v1
+2020-09-16,Fast convex optimization via inertial dynamics combining viscous and Hessian-driven damping with time rescaling,"In a Hilbert setting, we develop fast methods for convex unconstrained
+optimization. We rely on the asymptotic behavior of an inertial system
+combining geometric damping with temporal scaling. The convex function to
+minimize enters the dynamic via its gradient. The dynamic includes three
+coefficients varying with time, one is a viscous damping coefficient, the
+second is attached to the Hessian-driven damping, the third is a time scaling
+coefficient. We study the convergence rate of the values under general
+conditions involving the damping and the time scale coefficients. The obtained
+results are based on a new Lyapunov analysis and they encompass known results
+on the subject. We pay particular attention to the case of an asymptotically
+vanishing viscous damping, which is directly related to the accelerated
+gradient method of Nesterov. The Hessian-driven damping significantly reduces
+the oscillatory aspects. As a main result, we obtain an exponential rate of
+convergence of values without assuming the strong convexity of the objective
+function. The temporal discretization of these dynamics opens the gate to a
+large class of inertial optimization algorithms.",2009.07620v1
+2021-08-04,Nonlinear fluid damping of elastically mounted pitching wings in quiescent water,"We experimentally study the nonlinear fluid damping of a rigid but
+elastically mounted pitching wing in the absence of a freestream flow. The
+dynamics of the elastic mount are simulated using a cyber-physical system. We
+perturb the wing and measure the fluid damping coefficient from damped
+oscillations over a large range of pitching frequencies, pitching amplitudes,
+pivot locations and sweep angles. A universal fluid damping scaling is proposed
+to incorporate all these parameters. Flow fields obtained using particle image
+velocimetry are analyzed to explain the nonlinear behaviors of the fluid
+damping.",2108.02090v1
+2023-07-05,Optimal damping of vibrating systems: dependence on initial conditions,"Common criteria used for measuring performance of vibrating systems have one
+thing in common: they do not depend on initial conditions of the system. In
+some cases it is assumed that the system has zero initial conditions, or some
+kind of averaging is used to get rid of initial conditions. The aim of this
+paper is to initiate rigorous study of the dependence of vibrating systems on
+initial conditions in the setting of optimal damping problems. We show that,
+based on the type of initial conditions, especially on the ratio of potential
+and kinetic energy of the initial conditions, the vibrating system will have
+quite different behavior and correspondingly the optimal damping coefficients
+will be quite different. More precisely, for single degree of freedom systems
+and the initial conditions with mostly potential energy, the optimal damping
+coefficient will be in the under-damped regime, while in the case of the
+predominant kinetic energy the optimal damping coefficient will be in the
+over-damped regime. In fact, in the case of pure kinetic initial energy, the
+optimal damping coefficient is $+\infty$! Qualitatively, we found the same
+behavior in multi degree of freedom systems with mass proportional damping. We
+also introduce a new method for determining the optimal damping of vibrating
+systems, which takes into account the peculiarities of initial conditions and
+the fact that, although in theory these systems asymptotically approach
+equilibrium and never reach it exactly, in nature and in experiments they
+effectively reach equilibrium in some finite time.",2307.02352v2
+2021-06-25,Perturbed primal-dual dynamics with damping and time scaling coefficients for affine constrained convex optimization problems,"In Hilbert space, we propose a family of primal-dual dynamical system for
+affine constrained convex optimization problem. Several damping coefficients,
+time scaling coefficients, and perturbation terms are thus considered. By
+constructing the energy functions, we investigate the convergence rates with
+different choices of the damping coefficients and time scaling coefficients.
+Our results extend the inertial dynamical approaches for unconstrained convex
+optimization problems to affine constrained convex optimization problems.",2106.13702v1
+2020-06-24,Stability of a star-shaped network with local Kelvin-Voigt damping and non-smooth coefficient at interface,"In this paper, we study the stability problem of a star-shaped network of
+elastic strings with a local Kelvin-Voigt damping. Under the assumption that
+the damping coefficients have some singularities near the transmission point,
+we prove that the semigroup corresponding to the system is polynomially stable
+and the decay rates depends on the speed of the degeneracy. This result
+improves the decay rate of the semigroup associated to the system on an earlier
+result of Z.~Liu and Q.~Zhang in \cite{LZ} involving the wave equation with
+local Kelvin-Voigt damping and non-smooth coefficient at interface.",2006.14949v1
+2008-05-07,Comparison Between Damping Coefficients of Measured Perforated Micromechanical Test Structures and Compact Models,"Measured damping coefficients of six different perforated micromechanical
+test structures are compared with damping coefficients given by published
+compact models. The motion of the perforated plates is almost translational,
+the surface shape is rectangular, and the perforation is uniform validating the
+assumptions made for compact models. In the structures, the perforation ratio
+varies from 24% - 59%. The study of the structure shows that the
+compressibility and inertia do not contribute to the damping at the frequencies
+used (130kHz - 220kHz). The damping coefficients given by all four compact
+models underestimate the measured damping coefficient by approximately 20%. The
+reasons for this underestimation are discussed by studying the various flow
+components in the models.",0805.0893v1
+2003-02-17,Magnetization dynamics with a spin-transfer torque,"The magnetization reversal and dynamics of a spin valve pillar, whose lateral
+size is 64$\times$64 nm$^2$, are studied by using micromagnetic simulation in
+the presence of spin transfer torque. Spin torques display both characteristics
+of magnetic damping (or anti-damping) and of an effective magnetic field. For a
+steady-state current, both M-I and M-H hysteresis loops show unique features,
+including multiple jumps, unusual plateaus and precessional states. These
+states originate from the competition between the energy dissipation due to
+Gilbert damping and the energy accumulation due to the spin torque supplied by
+the spin current. The magnetic energy oscillates as a function of time even for
+a steady-state current. For a pulsed current, the minimum width and amplitude
+of the spin torque for achieving current-driven magnetization reversal are
+quantitatively determined. The spin torque also shows very interesting thermal
+activation that is fundamentally different from an ordinary damping effect.",0302337v1
+2003-10-13,Domain wall mobility in nanowires: transverse versus vortex walls,"The motion of domain walls in ferromagnetic, cylindrical nanowires is
+investigated numerically by solving the Landau-Lifshitz-Gilbert equation for a
+classical spin model in which energy contributions from exchange, crystalline
+anisotropy, dipole-dipole interaction, and a driving magnetic field are
+considered. Depending on the diameter, either transverse domain walls or vortex
+walls are found. The transverse domain wall is observed for diameters smaller
+than the exchange length of the given material. Here, the system behaves
+effectively one-dimensional and the domain wall mobility agrees with a result
+derived for a one-dimensional wall by Slonczewski. For low damping the domain
+wall mobility decreases with decreasing damping constant. With increasing
+diameter, a crossover to a vortex wall sets in which enhances the domain wall
+mobility drastically. For a vortex wall the domain wall mobility is described
+by the Walker-formula, with a domain wall width depending on the diameter of
+the wire. The main difference is the dependence on damping: for a vortex wall
+the domain wall mobility can be drastically increased for small values of the
+damping constant up to a factor of $1/\alpha^2$.",0310277v1
+2013-10-29,Observational Study of Large Amplitude Longitudinal Oscillations in a Solar Filament,"On 20 August 2010 an energetic disturbance triggered damped large-amplitude
+longitudinal (LAL) oscillations in almost an entire filament. In the present
+work we analyze this periodic motion in the filament to characterize the
+damping and restoring mechanism of the oscillation. Our method involves placing
+slits along the axis of the filament at different angles with respect to the
+spine of the filament, finding the angle at which the oscillation is clearest,
+and fitting the resulting oscillation pattern to decaying sinusoidal and Bessel
+functions. These functions represent the equations of motion of a pendulum
+damped by mass accretion. With this method we determine the period and the
+decaying time of the oscillation. Our preliminary results support the theory
+presented by Luna and Karpen (2012) that the restoring force of LAL
+oscillations is solar gravity in the tubes where the threads oscillate, and the
+damping mechanism is the ongoing accumulation of mass onto the oscillating
+threads. Following an earlier paper, we have determined the magnitude and
+radius of curvature of the dipped magnetic flux tubes hosting a thread along
+the filament, as well as the mass accretion rate of the filament threads, via
+the fitted parameters.",1310.7657v1
+2014-12-08,Magnetization Dynamics driven by Non-equilibrium Spin-Orbit Coupled Electron Gas,"The dynamics of magnetization coupled to an electron gas via s-d exchange
+interaction is investigated by using density matrix technique. Our theory shows
+that non-equilibrium spin accumulation induces a spin torque and the electron
+bath leads to a damping of the magnetization. For the two-dimensional
+magnetization thin film coupled to the electron gas with Rashba spin-orbit
+coupling, the result for the spin-orbit torques is consistent with the previous
+semi-classical theory. Our theory predicts a damping of the magnetization,
+which is absent in the semi-classical theory. The magnitude of the damping due
+to the electron bath is comparable to the intrinsic Gilbert damping and may be
+important in describing the magnetization dynamics of the system.",1412.2479v1
+2017-03-06,Damping dependence of spin-torque effects in thermally assisted magnetization reversal,"Thermal fluctuations of nanomagnets driven by spin-polarized currents are
+treated via the Landau-Lifshitz-Gilbert equation as generalized to include both
+the random thermal noise field and Slonczewski spin-transfer torque terms. The
+magnetization reversal time of such a nanomagnet is then evaluated for wide
+ranges of damping by using a method which generalizes the solution of the
+so-called Kramers turnover problem for mechanical Brownian particles, thereby
+bridging the very low damping and intermediate damping Kramers escape rates, to
+the analogous magnetic turnover problem. The reversal time is then evaluated
+for a nanomagnet with the free energy density given in the standard form of
+superimposed easy-plane and in-plane easy-axis anisotropies with the dc bias
+field along the easy axis.",1703.01879v5
+2017-05-09,Low spin wave damping in the insulating chiral magnet Cu$_{2}$OSeO$_{3}$,"Chiral magnets with topologically nontrivial spin order such as Skyrmions
+have generated enormous interest in both fundamental and applied sciences. We
+report broadband microwave spectroscopy performed on the insulating chiral
+ferrimagnet Cu$_{2}$OSeO$_{3}$. For the damping of magnetization dynamics we
+find a remarkably small Gilbert damping parameter of about $1\times10^{-4}$ at
+5 K. This value is only a factor of 4 larger than the one reported for the best
+insulating ferrimagnet yttrium iron garnet. We detect a series of sharp
+resonances and attribute them to confined spin waves in the mm-sized samples.
+Considering the small damping, insulating chiral magnets turn out to be
+promising candidates when exploring non-collinear spin structures for high
+frequency applications.",1705.03416v1
+2018-09-04,Separation of the two-magnon scattering contribution to damping for the determination of the spin mixing conductance,"We present angle dependent measurements of the damping properties of
+epitaxial Fe layers with MgO, Al and Pt capping layers. Based on the
+preferential distribution of lattice defects following the crystal symmetry, we
+make use of a model of the defect density to separate the contribution of
+two-magnon scattering to the damping from the isotropic contribution
+originating in the spin pumping effect, the viscous Gilbert damping and the
+magnetic proximity effect. The separation of the two-magnon contribution, which
+depends strongly on the defect density, allows for the measurement of a value
+of the effective spin mixing conductance which is closer to the value
+exclusively due to spin pumping. The influence of the defect density for
+bilayers systems due to the different capping layers and to the unavoidable
+spread in defect density from sample to sample is thus removed. This shows the
+potential of studying spin pumping phenomena in fully ordered systems in which
+this separation is possible, contrary to polycrystalline or amorphous metallic
+thin films.",1809.01042v1
+2011-11-27,A two-stage approach to relaxation in billiard systems of locally confined hard spheres,"We consider the three-dimensional dynamics of systems of many interacting
+hard spheres, each individually confined to a dispersive environment, and show
+that the macroscopic limit of such systems is characterized by a coefficient of
+heat conduction whose value reduces to a dimensional formula in the limit of
+vanishingly small rate of interaction. It is argued that this limit arises from
+an effective loss of memory. Similarities with the diffusion of a tagged
+particle in binary mixtures are emphasized.",1111.6272v1
+2014-03-16,Interpolating local constants in families,"We extend the theory of local constants to l-adic families of representations
+of GL_n(F) where F is a p-adic field with l not equal to p. We construct zeta
+integrals and gamma factors for representations coming from the conjectural
+""local Langlands correspondence in families"" of Emerton-Helm, proving a
+rationality result and functional equation. We also construct a universal gamma
+factor with coefficients in the integral Bernstein center.",1403.3914v2
+2014-08-02,Machta-Zwanzig regime of anomalous diffusion in infinite-horizon billiards,"We study diffusion on a periodic billiard table with infinite horizon in the
+limit of narrow corridors. An effective trapping mechanism emerges according to
+which the process can be modeled by a L\'evy walk combining
+exponentially-distributed trapping times with free propagation along paths
+whose precise probabilities we compute. This description yields an
+approximation of the mean squared displacement of infinite-horizon billiards in
+terms of two transport coefficients which generalizes to this anomalous regime
+the Machta-Zwanzig approximation of normal diffusion in finite-horizon
+billiards [Phys. Rev. Lett. 50, 1959 (1983)].",1408.0349v1
+2022-12-22,Novel Bottomonium Results,"We present the latest results from the use of the Backus-Gilbert method for
+reconstructing the spectra of NRQCD bottomonium mesons using anisotropic
+FASTSUM ensembles at non-zero temperature. We focus in particular on results
+from the $\eta_b$, $\Upsilon$, $\chi_{b1}$ and $h_b$ generated from
+Tikhonov-regularized Backus-Gilbert coefficient sets. We extend previous work
+on the Laplace shifting theorem as a means of resolution improvement and
+present new results from its use. We conclude with a discussion of the
+limitations of the improvement routine and elucidate a connection with
+Parisi-Lepage statistical scaling.",2212.12016v1
+2023-11-29,Bayesian interpretation of Backus-Gilbert methods,"The extraction of spectral densities from Euclidean correlators evaluated on
+the lattice is an important problem, as these quantities encode physical
+information on scattering amplitudes, finite-volume spectra, inclusive decay
+rates, and transport coefficients. In this contribution, we show that the
+Bayesian approach to this ""inverse"" problem, based on Gaussian processes, can
+be reformulated in a way that yields a solution equivalent, up to statistical
+uncertainties, to the one obtained in a Backus-Gilbert approach. After
+discussing this equivalence, we point out its implications for a reliable
+determination of spectral densities from lattice simulations.",2311.18125v1
+2006-02-09,Magnetization damping in polycrystalline Co ultra-thin films: Evidence for non-local effects,"The magnetic properties and magnetization dynamics of polycrystalline
+ultra-thin Co layers were investigated using a broadband ferromagnetic
+resonance (FMR) technique at room temperature. A variable thickness (1 nm $\leq
+t \leq$ 10 nm) Co layer is sandwiched between 10 nm thick Cu layers (10 nm Cu|
+t Co|10 nm Cu), while materials in contact with the Cu outer interfaces are
+varied to determine their influence on the magnetization damping. The resonance
+field and the linewidth were studied for in-plane magnetic fields in field
+swept experiments at a fixed frequency, from 4 to 25 GHz. The Co layers have a
+lower magnetization density than the bulk, and an interface contribution to the
+magnetic anisotropy normal to the film plane. The Gilbert damping, as
+determined from the frequency dependence of the linewidth, increases with
+decreasing Co layer thickness for films with outer Pt layers. This enhancement
+is not observed in structures without Pt layers. The result can be understood
+in terms of a non-local contribution to the damping due to spin pumping from Co
+through the Cu layer and spin relaxation in Pt layers. Pt layers just 1.5 nm
+thick are found to be sufficient to enhance the damping and thus act as
+efficient ""spin-sinks"". In structures with Pt outer layers, this non-local
+contribution to the damping becomes predominant when the Co layer is thinner
+than 4 nm.",0602243v2
+2020-04-09,Magnetic Damping in Epitaxial Fe Alloyed with Vanadium and Aluminum,"To develop low-moment, low-damping metallic ferromagnets for power-efficient
+spintronic devices, it is crucial to understand how magnetic relaxation is
+impacted by the addition of nonmagnetic elements. Here, we compare magnetic
+relaxation in epitaxial Fe films alloyed with light nonmagnetic elements of V
+and Al. FeV alloys exhibit lower intrinsic damping compared to pure Fe, reduced
+by nearly a factor of 2, whereas damping in FeAl alloys increases with Al
+content. Our experimental and computational results indicate that reducing the
+density of states at the Fermi level, rather than the average atomic number,
+has a more significant impact in lowering damping in Fe alloyed with light
+elements. Moreover, FeV is confirmed to exhibit an intrinsic Gilbert damping
+parameter of $\simeq$0.001, among the lowest ever reported for ferromagnetic
+metals.",2004.04840v3
+2016-05-17,Simultaneous Identification of Damping Coefficient and Initial Value in PDEs from boundary measurement,"In this paper, the simultaneous identification of damping or anti-damping
+coefficient and initial value for some PDEs is considered. An identification
+algorithm is proposed based on the fact that the output of system happens to be
+decomposed into a product of an exponential function and a periodic function.
+The former contains information of the damping coefficient, while the latter
+does not. The convergence and error analysis are also developed. Three
+examples, namely an anti-stable wave equation with boundary anti-damping, the
+Schr\""odinger equation with internal anti-damping, and two connected strings
+with middle joint anti-damping, are investigated and demonstrated by numerical
+simulations to show the effectiveness of the proposed algorithm.",1605.05063v1
+2020-03-13,Anharmonic phonon damping enhances the $T_c$ of BCS-type superconductors,"A theory of superconductivity is presented where the effect of anharmonicity,
+as entailed in the acoustic, or optical, phonon damping, is explicitly
+considered in the pairing mechanism. The gap equation is solved including
+diffusive Akhiezer damping for longitudinal acoustic phonons or Klemens damping
+for optical phonons, with a damping coefficient which, in either case, can be
+directly related to the Gruneisen parameter and hence to the anharmonic
+coefficients in the interatomic potential. The results show that the increase
+of anharmonicity has a strikingly non-monotonic effect on the critical
+temperature $T_{c}$. The optimal damping coefficient yielding maximum $T_c$ is
+set by the velocity of the bosonic mediator. This theory may open up
+unprecedented opportunities for material design where $T_{c}$ may be tuned via
+the anharmonicity of the interatomic potential, and presents implications for
+the superconductivity in the recently discovered hydrides, where anharmonicity
+is very strong and for which the anharmonic damping is especially relevant.",2003.06220v2
+2014-05-19,"Comparison of micromagnetic parameters of ferromagnetic semiconductors (Ga,Mn)(As,P) and (Ga,Mn)As","We report on the determination of micromagnetic parameters of epilayers of
+the ferromagnetic semiconductor (Ga,Mn)As, which has easy axis in the sample
+plane, and (Ga,Mn)(As,P) which has easy axis perpendicular to the sample plane.
+We use an optical analog of ferromagnetic resonance where the
+laser-pulse-induced precession of magnetization is measured directly in the
+time domain. By the analysis of a single set of pump-and-probe magneto-optical
+data we determined the magnetic anisotropy fields, the spin stiffness and the
+Gilbert damping constant in these two materials. We show that incorporation of
+10% of phosphorus in (Ga,Mn)As with 6% of manganese leads not only to the
+expected sign change of the perpendicular to plane anisotropy field but also to
+an increase of the Gilbert damping and to a reduction of the spin stiffness.
+The observed changes in the micromagnetic parameters upon incorporating P in
+(Ga,Mn)As are consistent with the reduced hole density, conductivity, and Curie
+temperature of the (Ga,Mn)(As,P) material. We report that the magnetization
+precession damping is stronger for the n = 1 spin wave resonance mode than for
+the n = 0 uniform magnetization precession mode.",1405.4677v1
+2015-03-24,Spin dynamics and frequency dependence of magnetic damping study in soft ferromagnetic FeTaC film with a stripe domain structure,"Perpendicular magnetic anisotropy (PMA) and low magnetic damping are the key
+factors for the free layer magnetization switching by spin transfer torque
+technique in magnetic tunnel junction devices. The magnetization precessional
+dynamics in soft ferromagnetic FeTaC thin film with a stripe domain structure
+was explored in broad band frequency range by employing micro-strip
+ferromagnetic resonance technique. The polar angular variation of resonance
+field and linewidth at different frequencies have been analyzed numerically
+using Landau-Lifshitz-Gilbert equation by taking into account the total free
+energy density of the film. The numerically estimated parameters Land\'{e}
+$g$-factor, PMA constant, and effective magnetization are found to be 2.1,
+2$\times10^{5}$ erg/cm$^{3}$ and 7145 Oe, respectively. The frequency
+dependence of Gilbert damping parameter ($\alpha$) is evaluated by considering
+both intrinsic and extrinsic effects into the total linewidth analysis. The
+value of $\alpha$ is found to be 0.006 at 10 GHz and it increases with
+decreasing precessional frequency.",1503.07043v5
+2016-05-22,Low Gilbert damping in Co2FeSi and Fe2CoSi films,"Thin highly textured Fe$_{\mathrm{1+x}}$Co$_{\mathrm{2-x}}$Si ($0 \leq$ x
+$\leq 1$) films were prepared on MgO (001) substrates by magnetron
+co-sputtering. The magneto-optic Kerr effect (MOKE) and ferromagnetic resonance
+(FMR) measurements were used to investigate the composition dependence of the
+magnetization, the magnetic anisotropy, the gyromagnetic ratio and the
+relaxation of the films. The effective magnetization for the thin
+Fe$_{\mathrm{1+x}}$Co$_{\mathrm{2-x}}$Si films, determined by FMR measurements,
+are consistent with the Slater Pauling prediction. Both MOKE and FMR
+measurements reveal a pronounced fourfold anisotropy distribution for all
+films. In addition we found a strong influence of the stoichiometry on the
+anisotropy as the cubic anisotropy strongly increases with increasing Fe
+concentration. The gyromagnetic ratio is only weakly dependent on the
+composition. We find low Gilbert damping parameters for all films with values
+down to $0.0012\pm0.00012$ for Fe$_{1.75}$Co$_{1.25}$Si. The effective damping
+parameter for Co$_2$FeSi is found to be $0.0018\pm 0.0004$. We also find a
+pronounced anisotropic relaxation, which indicates significant contributions of
+two-magnon scattering processes that is strongest along the easy axes of the
+films. This makes thin Fe$_{\mathrm{1+x}}$Co$_{\mathrm{2-x}}$Si films ideal
+materials for the application in STT-MRAM devices.",1605.06797v1
+2017-09-21,Low Gilbert Damping Constant in Perpendicularly Magnetized W/CoFeB/MgO Films with High Thermal Stability,"Perpendicular magnetic materials with low damping constant and high thermal
+stability have great potential for realizing high-density, non-volatile, and
+low-power consumption spintronic devices, which can sustain operation
+reliability for high processing temperatures. In this work, we study the
+Gilbert damping constant ({\alpha}) of perpendicularly magnetized W/CoFeB/MgO
+films with a high perpendicular magnetic anisotropy (PMA) and superb thermal
+stability. The {\alpha} of these PMA films annealed at different temperatures
+is determined via an all-optical Time-Resolved Magneto-Optical Kerr Effect
+method. We find that {\alpha} of these W/CoFeB/MgO PMA films decreases with
+increasing annealing temperature, reaches a minimum of {\alpha} = 0.016 at an
+annealing temperature of 350 {\deg}C, and then increases to 0.024 after
+post-annealing at 400 {\deg}C. The minimum {\alpha} observed at 350 {\deg}C is
+rationalized by two competing effects as the annealing temperature becomes
+higher: the enhanced crystallization of CoFeB and dead-layer growth occurring
+at the two interfaces of the CoFeB layer. We further demonstrate that {\alpha}
+of the 400 {\deg}C-annealed W/CoFeB/MgO film is comparable to that of a
+reference Ta/CoFeB/MgO PMA film annealed at 300 {\deg}C, justifying the
+enhanced thermal stability of the W-seeded CoFeB films.",1709.07483v1
+2022-02-06,Enhancing Perpendicular Magnetic Anisotropy in Garnet Ferrimagnet by Interfacing with Few-Layer WTe2,"Engineering magnetic anisotropy in a ferro- or ferrimagnetic (FM) thin film
+is crucial in spintronic device. One way to modify the magnetic anisotropy is
+through the surface of the FM thin film. Here, we report the emergence of a
+perpendicular magnetic anisotropy (PMA) induced by interfacial interactions in
+a heterostructure comprised of a garnet ferrimagnet, Y3Fe5O12 (YIG), and the
+low-symmetry, high spin orbit coupling (SOC) transition metal dichalcogenide,
+WTe2. At the same time, we also observed an enhancement in Gilbert damping in
+the WTe2 covered YIG area. Both the magnitude of interface-induced PMA and the
+Gilbert damping enhancement have no observable WTe2 thickness dependence down
+to single quadruple-layer, indicating that the interfacial interaction plays a
+critical role. The ability of WTe2 to enhance the PMA in FM thin film, combined
+with its previously reported capability to generate out-of-plane damping like
+spin torque, makes it desirable for magnetic memory applications.",2202.02834v1
+2022-05-27,Scalar field damping at high temperatures,"The motion of a scalar field that interacts with a hot plasma, like the
+inflaton during reheating, is damped, which is a dissipative process. At high
+temperatures the damping can be described by a local term in the effective
+equation of motion. The damping coefficient is sensitive to multiple
+scattering. In the loop expansion its computation would require an all-order
+resummation. Instead we solve an effective Boltzmann equation, similarly to the
+computation of transport coefficients. For an interaction with another scalar
+field we obtain a simple relation between the damping coefficient and the bulk
+viscosity, so that one can make use of known results for the latter. The
+numerical prefactor of the damping coefficient turns out to be rather large, of
+order $ 10 ^ 4 $.",2205.14166v2
+2022-12-02,Equivalence between the energy decay of fractional damped Klein-Gordon equations and geometric conditions for damping coefficients,"We consider damped $s$-fractional Klein--Gordon equations on $\mathbb{R}^d$,
+where $s$ denotes the order of the fractional Laplacian. In the one-dimensional
+case $d = 1$, Green (2020) established that the exponential decay for $s \geq
+2$ and the polynomial decay of order $s/(4-2s)$ hold if and only if the damping
+coefficient function satisfies the so-called geometric control condition. In
+this note, we show that the $o(1)$ energy decay is also equivalent to these
+conditions in the case $d=1$. Furthermore, we extend this result to the
+higher-dimensional case: the logarithmic decay, the $o(1)$ decay, and the
+thickness of the damping coefficient are equivalent for $s \geq 2$. In
+addition, we also prove that the exponential decay holds for $0 < s < 2$ if and
+only if the damping coefficient function has a positive lower bound, so in
+particular, we cannot expect the exponential decay under the geometric control
+condition.",2212.01029v4
+2017-06-13,Uniform energy decay for wave equations with unbounded damping coefficients,"We consider the Cauchy problem for wave equations with unbounded damping
+coefficients in the whole space. For a general class of unbounded damping
+coefficients, we derive uniform total energy decay estimates together with a
+unique existence result of a weak solution. In this case we never impose strong
+assumptions such as compactness of the support of the initial data. This means
+that we never rely on the finite propagation speed property of the solution,
+and we try to deal with an essential unbounded coefficient case.",1706.03942v1
+2021-06-09,Grammage of cosmic rays in the proximity of supernova remnants embedded in a partially ionized medium,"We investigate the damping of Alfv\'en waves generated by the cosmic ray
+resonant streaming instability in the context of the cosmic ray escape and
+propagation in the proximity of supernova remnants. We consider ion-neutral
+damping, turbulent damping and non linear Landau damping in the warm ionized
+and warm neutral phases of the interstellar medium. For the ion-neutral
+damping, up-to-date damping coefficients are used. We investigate in particular
+whether the self-confinement of cosmic rays nearby sources can appreciably
+affect the grammage. We show that the ion-neutral damping and the turbulent
+damping effectively limit the residence time of cosmic rays in the source
+proximity, so that the grammage accumulated near sources is found to be
+negligible. Contrary to previous results, this also happens in the most extreme
+scenario where ion-neutral damping is less effective, namely in a medium with
+only neutral helium and fully ionized hydrogen. Therefore, the standard
+picture, in which CR secondaries are produced during the whole time spent by
+cosmic rays throughout the Galactic disk, need not to be deeply revisited.",2106.04948v1
+2023-02-23,Buckling Metamaterials for Extreme Vibration Damping,"Damping mechanical resonances is a formidable challenge in an increasing
+number of applications. Many of the passive damping methods rely on using low
+stiffness dissipative elements, complex mechanical structures or electrical
+systems, while active vibration damping systems typically add an additional
+layer of complexity. However, in many cases, the reduced stiffness or
+additional complexity and mass render these vibration damping methods
+unfeasible. Here, we introduce a method for passive vibration damping by
+allowing buckling of the primary load path, which sets an upper limit for
+vibration transmission: the transmitted acceleration saturates at a maximum
+value, no matter what the input acceleration is. This nonlinear mechanism leads
+to an extreme damping coefficient tan delta ~0.23 in our metal
+metamaterial|orders of magnitude larger than the linear damping of traditional
+lightweight structural materials. We demonstrate this principle experimentally
+and numerically in free-standing rubber and metal mechanical metamaterials over
+a range of accelerations, and show that bi-directional buckling can further
+improve its performance. Buckling metamaterials pave the way towards extreme
+vibration damping without mass or stiffness penalty, and as such could be
+applicable in a multitude of high-tech applications, including aerospace
+structures, vehicles and sensitive instruments.",2302.11968v1
+2014-03-19,The effects of time-dependent dissipation on the basins of attraction for the pendulum with oscillating support,"We consider a pendulum with vertically oscillating support and time-dependent
+damping coefficient which varies until reaching a finite final value. The sizes
+of the corresponding basins of attraction are found to depend strongly on the
+full evolution of the dissipation. In order to predict the behaviour of the
+system, it is essential to understand how the sizes of the basins of attraction
+for constant dissipation depend on the damping coefficient. For values of the
+parameters in the perturbation regime, we characterise analytically the
+conditions under which the attractors exist and study numerically how the sizes
+of their basins of attraction depend on the damping coefficient. Away from the
+perturbation regime, a numerical study of the attractors and the corresponding
+basins of attraction for different constant values of the damping coefficient
+produces a much more involved scenario: changing the magnitude of the
+dissipation causes some attractors to disappear either leaving no trace or
+producing new attractors by bifurcation, such as period doubling and
+saddle-node bifurcation. For an initially non-constant damping coefficient,
+both increasing and decreasing to some finite final value, we numerically
+observe that, when the damping coefficient varies slowly from a finite initial
+value to a different final value, without changing the set of attractors, the
+slower the variation the closer the sizes of the basins of attraction are to
+those they have for constant damping coefficient fixed at the initial value. If
+during the variation of the damping coefficient attractors appear or disappear,
+remarkable additional phenomena may occur. For instance, a fixed point
+asymptotically may attract the entire phase space, up to a zero measure set,
+even though no attractor with such a property exists for any value of the
+damping coefficient between the extreme values.",1403.4996v1
+2016-08-14,Mechanical energy and mean equivalent viscous damping for SDOF fractional oscillators,"This paper addresses the total mechanical energy of a single degree of
+freedom fractional oscillator. Based on the energy storage and dissipation
+properties of the Caputo fractional derivatives, the expression for total
+mechanical energy in the single degree of freedom fractional oscillator is
+firstly presented. The energy regeneration due to the external exciting force
+and the energy loss due to the fractional damping force during the vibratory
+motion are analyzed. Furthermore, based on the mean energy dissipation of the
+fractional damping element in steady-state vibration, a new concept of mean
+equivalent viscous damping is suggested and the value of the damping
+coefficient is evaluated.",1608.04071v1
+2023-09-26,Qualitative properties of solutions to a nonlinear transmission problem for an elastic Bresse beam,"We consider a nonlinear transmission problem for a Bresse beam, which
+consists of two parts, damped and undamped. The mechanical damping in the
+damped part is present in the shear angle equation only, and the damped part
+may be of arbitrary positive length. We prove well-posedness of the
+corresponding PDE system in energy space and establish existence of a regular
+global attractor under certain conditions on nonlinearities and coefficients of
+the damped part only. Moreover, we study singular limits of the problem when
+$l\to 0$ or $l\to 0$ simultaneously with $k_i\to +\infty$ and perform numerical
+modelling for these processes.",2309.15171v2
+2016-09-05,Remarks on an elliptic problem arising in weighted energy estimates for wave equations with space-dependent damping term in an exterior domain,"This paper is concerned with weighted energy estimates and diffusion
+phenomena for the initial-boundary problem of the wave equation with
+space-dependent damping term in an exterior domain. In this analysis, an
+elliptic problem was introduced by Todorova and Yordanov. This attempt was
+quite useful when the coefficient of the damping term is radially symmetric. In
+this paper, by modifying their elliptic problem, we establish weighted energy
+estimates and diffusion phenomena even when the coefficient of the damping term
+is not radially symmetric.",1609.01063v2
+2017-03-09,Long-time dynamics of the strongly damped semilinear plate equation in $\mathbb{R}^{n}$,"We investigate the initial-value problem for the semilinear plate equation
+containing localized strong damping, localized weak damping and nonlocal
+nonlinearity. We prove that if nonnegative damping coefficients are strictly
+positive almost everywhere in the exterior of some ball and the sum of these
+coefficients is positive a.e. in $%
+  \mathbb{R}
+  ^{n}$, then the semigroup generated by the considered problem possesses a
+global attractor in $H^{2}\left(
+  \mathbb{R}
+  ^{n}\right) \times L^{2}\left(
+  \mathbb{R}
+  ^{n}\right) $. We also establish boundedness of this attractor in $
+H^{3}\left(
+  \mathbb{R}
+  ^{n}\right) \times H^{2}\left(
+  \mathbb{R} ^{n}\right) $.",1703.03485v2
+2020-11-06,A generalized finite element method for the strongly damped wave equation with rapidly varying data,"We propose a generalized finite element method for the strongly damped wave
+equation with highly varying coefficients. The proposed method is based on the
+localized orthogonal decomposition introduced and is designed to handle
+independent variations in both the damping and the wave propagation speed
+respectively. The method does so by automatically correcting for the damping in
+the transient phase and for the propagation speed in the steady state phase.
+Convergence of optimal order is proven in $L_2(H^1)$-norm, independent of the
+derivatives of the coefficients. We present numerical examples that confirm the
+theoretical findings.",2011.03311v1
+2022-10-30,Intrinsic polynomial squeezing for Balakrishnan-Taylor beam models,"We explore the energy decay properties related to a model in extensible beams
+with the so-called energy damping. We investigate the influence of the
+nonloncal damping coefficient in the stability of the model. We prove, for the
+first time, that the corresponding energy functional is squeezed by
+polynomial-like functions involving the power of the damping coefficient, which
+arises intrinsically from the Balakrishnan-Taylor beam models. As a
+consequence, it is shown that such models with nonlocal energy damping are
+never exponentially stable in its essence.",2210.16931v1
+2020-11-16,Technology to Counter Online Flaming Based on the Frequency-Dependent Damping Coefficient in the Oscillation Model,"Online social networks, which are remarkably active, often experience
+explosive user dynamics such as online flaming, which can significantly impact
+the real world. However, countermeasures based on social analyses of the
+individuals causing flaming are too slow to be effective because of the
+rapidity with which the influence of online user dynamics propagates. A
+countermeasure technology for the flaming phenomena based on the oscillation
+model, which describes online user dynamics, has been proposed; it is an
+immediate solution as it does not depend on social analyses of individuals.
+Conventional countermeasures based on the oscillation model assume that the
+damping coefficient is a constant regardless of the eigenfrequency. This
+assumption is, however, problematic as the damping coefficients are, in
+general, inherently frequency-dependent; the theory underlying the dependence
+is being elucidated. This paper discusses a design method that uses the damping
+coefficient to prevent flaming under general conditions considering the
+frequency-dependence of the damping coefficient and proposes a countermeasure
+technology for the flaming phenomena.",2011.08117v1
+2018-10-25,Time-retarded damping and magnetic inertia in the Landau-Lifshitz-Gilbert equation self-consistently coupled to electronic time-dependent nonequilibrium Green functions,"The conventional Landau-Lifshitz-Gilbert (LLG) equation is a widely used tool
+to describe dynamics of local magnetic moments, viewed as classical vectors of
+fixed length, with their change assumed to take place simultaneously with the
+cause. Here we demonstrate that recently developed [M. D. Petrovi\'{c} {\em et
+al.}, {\tt arXiv:1802.05682}] self-consistent coupling of the LLG equation to
+time-dependent quantum-mechanical description of electrons microscopically
+generates time-retarded damping in the LLG equation described by a memory
+kernel which is also spatially dependent. For sufficiently slow dynamics of
+local magnetic moments, the memory kernel can be expanded to extract the
+Gilbert damping (proportional to first time derivative of magnetization) and
+magnetic inertia (proportional to second time derivative of magnetization)
+terms whose parameters, however, are time-dependent in contrast to
+time-independent parameters used in the conventional LLG equation. We use
+examples of single or multiple magnetic moments precessing in an external
+magnetic field, as well as field-driven motion of a magnetic domain wall (DW),
+to quantify the difference in their time evolution computed from conventional
+LLG equation vs. TDNEGF+LLG quantum-classical hybrid approach. The faster DW
+motion predicted by TDNEGF+LLG approach reveals that important quantum effects,
+stemming from finite amount of time which it takes for conduction electron spin
+to react to the motion of classical local magnetic moments, are missing from
+conventional classical micromagnetics simulations. We also demonstrate large
+discrepancy between TDNEGF+LLG-computed numerically exact and, therefore,
+nonperturbative result for charge current pumped by a moving DW and the same
+quantity computed by perturbative spin motive force formula combined with the
+conventional LLG equation.",1810.11016v2
+2019-08-08,Annihilation of topological solitons in magnetism with spin wave burst finale: The role of nonequilibrium electrons causing nonlocal damping and spin pumping over ultrabroadband frequency range,"We not only reproduce burst of short-wavelength spin waves (SWs) observed in
+recent experiment [S. Woo et al., Nat. Phys. 13, 448 (2017)] on
+magnetic-field-driven annihilation of two magnetic domain walls (DWs) but,
+furthermore, we predict that this setup additionally generates highly unusual}
+pumping of electronic spin currents in the absence of any bias voltage. Prior
+to the instant of annihilation, their power spectrum is ultrabroadband, so they
+can be converted into rapidly changing in time charge currents, via the inverse
+spin Hall effect, as a source of THz radiation of bandwidth $\simeq 27$ THz
+where the lowest frequency is controlled by the applied magnetic field. The
+spin pumping stems from time-dependent fields introduced into the quantum
+Hamiltonian of electrons by the classical dynamics of localized magnetic
+moments (LMMs) comprising the domains. The pumped currents carry spin-polarized
+electrons which, in turn, exert backaction on LMMs in the form of nonlocal
+damping which is more than twice as large as conventional local Gilbert
+damping. The nonlocal damping can substantially modify the spectrum of emitted
+SWs when compared to widely-used micromagnetic simulations where conduction
+electrons are completely absent. Since we use fully microscopic (i.e.,
+Hamiltonian-based) framework, self-consistently combining time-dependent
+electronic nonequilibrium Green functions with the Landau-Lifshitz-Gilbert
+equation, we also demonstrate that previously derived phenomenological formulas
+miss ultrabroadband spin pumping while underestimating the magnitude of
+nonlocal damping due to nonequilibrium electrons.",1908.03194v5
+2020-09-23,Remark on the exponential decay of the solutions of the damped wave equation,"A condition which guaranties the exponential decay of the solutions of the
+initial-boundary value problem for the damped wave equation is proved. A method
+for the effective computability of the coefficient of exponential decay is also
+presented.",2009.11244v1
+2021-06-22,Choice of Damping Coefficient in Langevin Dynamics,"This article considers the application of Langevin dynamics to sampling and
+investigates how to choose the damping parameter in Langevin dynamics for the
+purpose of maximizing thoroughness of sampling. Also, it considers the
+computation of measures of sampling thoroughness.",2106.11597v1
+2004-03-12,Factorization of damped wave equations with cubic nonlinearities,"The recent factorization scheme that we introduced for nonlinear polynomial
+ODEs in math-ph/0401040 is applied to the interesting case of damped wave
+equations with cubic nonlinearities. Traveling kink solutions are possible in
+the plane defined by the kink velocity versus the damping coefficient only
+along hyperbolas that are plotted herein",0403022v1
+2002-08-07,Toward a Universal Model of Damping--Modified Coulomb Friction,"A modification of Coulomb's law of friction uses a variable coefficient of
+friction that depends on a power law in the energy of mechanical oscillation.
+Through the use of three different exponents: 0, 1/2 and 1; all commonly
+encountered non-viscous forms of damping are accommodated. The nonlinear model
+appears to yield good agreement with experiment in cases of surface, internal,
+and amplitude dependent damping.",0208025v1
+2012-12-08,A note on the lifespan of solutions to the semilinear damped wave equation,"This paper concerns estimates of the lifespan of solutions to the semilinear
+damped wave equation. We give upper estimates of the lifespan for the
+semilinear damped wave equation with variable coefficients in all space
+dimensions.",1212.1772v3
+2018-03-20,Stability of the wave equations on a tree with local Kelvin-Voigt damping,"In this paper we study the stability problem of a tree of elastic strings
+with local Kelvin-Voigt damping on some of the edges. Under the compatibility
+condition of displacement and strain and continuity condition of damping
+coefficients at the vertices of the tree, exponential/polynomial stability are
+proved.",1803.07280v1
+2021-08-17,Spectral enclosures for the damped elastic wave equation,"In this paper we investigate spectral properties of the damped elastic wave
+equation. Deducing a correspondence between the eigenvalue problem of this
+model and the one of Lam\'e operators with non self-adjoint perturbations, we
+provide quantitative bounds on the location of the point spectrum in terms of
+suitable norms of the damping coefficient.",2108.07676v1
+2022-05-26,Ergodic results for the stochastic nonlinear Schrödinger equation with large damping,"We study the nonlinear Schr\""odinger equation with linear damping, i.e. a
+zero order dissipation, and additive noise. Working in $R^d$ with d = 2 or d =
+3, we prove the uniqueness of the invariant measure when the damping
+coefficient is sufficiently large.",2205.13364v1
+2016-08-30,Optimal damping ratios of multi-axial perfectly matched layers for elastic-wave modeling in general anisotropic media,"The conventional Perfectly Matched Layer (PML) is unstable for certain kinds
+of anisotropic media. This instability is intrinsic and independent of PML
+formulation or implementation. The Multi-axial PML (MPML) removes such
+instability using a nonzero damping coefficient in the direction parallel with
+the interface between a PML and the investigated domain. The damping ratio of
+MPML is the ratio between the damping coefficients along the directions
+parallel with and perpendicular to the interface between a PML and the
+investigated domain. No quantitative approach is available for obtaining these
+damping ratios for general anisotropic media. We develop a quantitative
+approach to determining optimal damping ratios to not only stabilize PMLs, but
+also minimize the artificial reflections from MPMLs. Numerical tests based on
+finite-difference method show that our new method can effectively provide a set
+of optimal MPML damping ratios for elastic-wave propagation in 2D and 3D
+general anisotropic media.",1608.08326v3
+2017-10-13,Mode-Dependent Damping in Metallic Antiferromagnets Due to Inter-Sublattice Spin Pumping,"Damping in magnetization dynamics characterizes the dissipation of magnetic
+energy and is essential for improving the performance of spintronics-based
+devices. While the damping of ferromagnets has been well studied and can be
+artificially controlled in practice, the damping parameters of
+antiferromagnetic materials are nevertheless little known for their physical
+mechanisms or numerical values. Here we calculate the damping parameters in
+antiferromagnetic dynamics using the generalized scattering theory of
+magnetization dissipation combined with the first-principles transport
+computation. For the PtMn, IrMn, PdMn and FeMn metallic antiferromagnets, the
+damping coefficient associated with the motion of magnetization ($\alpha_m$) is
+one to three orders of magnitude larger than the other damping coefficient
+associated with the variation of the N\'eel order ($\alpha_n$), in sharp
+contrast to the assumptions made in the literature.",1710.04766v1
+2020-03-29,Stability results for an elastic-viscoelastic waves interaction systems with localized Kelvin-Voigt damping and with an internal or boundary time delay,"We investigate the stability of a one-dimensional wave equation with non
+smooth localized internal viscoelastic damping of Kelvin-Voigt type and with
+boundary or localized internal delay feedback. The main novelty in this paper
+is that the Kelvin-Voigt and the delay damping are both localized via non
+smooth coefficients. In the case that the Kelvin-Voigt damping is localized
+faraway from the tip and the wave is subjected to a locally distributed
+internal or boundary delay feedback, we prove that the energy of the system
+decays polynomially of type t^{-4}. However, an exponential decay of the energy
+of the system is established provided that the Kelvin-Voigt damping is
+localized near a part of the boundary and a time delay damping acts on the
+second boundary. While, when the Kelvin-Voigt and the internal delay damping
+are both localized via non smooth coefficients near the tip, the energy of the
+system decays polynomially of type t^{-4}. Frequency domain arguments combined
+with piecewise multiplier techniques are employed.",2003.12967v1
+2023-09-15,On the formation of singularities for the slightly supercritical NLS equation with nonlinear damping,"We consider the focusing, mass-supercritical NLS equation augmented with a
+nonlinear damping term. We provide sufficient conditions on the nonlinearity
+exponents and damping coefficients for finite-time blow-up. In particular,
+singularities are formed for focusing and dissipative nonlinearities of the
+same power, provided that the damping coefficient is sufficiently small. Our
+result thus rigorously proves the non-regularizing effect of nonlinear damping
+in the mass-supercritical case, which was suggested by previous numerical and
+formal results.
+  We show that, under our assumption, the damping term may be controlled in
+such a way that the self-similar blow-up structure for the focusing NLS is
+approximately retained even within the dissipative evolution. The nonlinear
+damping contributes as a forcing term in the equation for the perturbation
+around the self-similar profile, that may produce a growth over finite time
+intervals. We estimate the error terms through a modulation analysis and a
+careful control of the time evolution of total momentum and energy functionals.",2309.08281v1
+2006-06-05,Phenomenological theory of current driven exchange switching in ferromagnetic nanojunctions,"Phenomenological approach is developed in the theory of spin-valve type
+ferromagnetic junctions to describe exchange switching by current flowing
+perpendicular to interfaces. Forward and backward current switching effects are
+described and they may be principally different in nature. Mobile electron
+spins are considered as being free in all the contacting ferromagnetic layers.
+Joint action of the following two current effects is investigated: the
+nonequilibrium longitudinal spin-injection effective field and the transverse
+spin-transfer surface torque. Dispersion relation for fluctuations is derived
+and solved for a junction model having spatially localized spin transfer
+torque: depth of the torque penetration into the free layer is assumed much
+smaller than the total free layer thickness. Some critical value of the well
+known Gilbert damping constant is established for the first time. Spin transfer
+torque dominates in the instability threshold determination for small enough
+damping constants, while the spin-injection effective field dominates for high
+damping. Fine interplay between spin transfer torque and spin injection is
+necessary to provide a hysteretic behavior of the resistance versus current
+dependence. The state diagram building up shows the possibility of
+non-stationary (time dependent) nonlinear states arising due to instability
+development. Calculations lead to the instability rise time values of the order
+of 0.1 ns. Spin wave resonance frequency spectrum softening occurs under the
+current growing to the instability threshold. Magnetization fluctuations above
+the threshold rise oscillating with time for low damping, but rise
+aperiodically and much more rapid for high damping.",0606102v2
+2015-07-29,Spin dynamics and relaxation in the classical-spin Kondo-impurity model beyond the Landau-Lifschitz-Gilbert equation,"The real-time dynamics of a classical spin in an external magnetic field and
+locally exchange coupled to an extended one-dimensional system of
+non-interacting conduction electrons is studied numerically. Retardation
+effects in the coupled electron-spin dynamics are shown to be the source for
+the relaxation of the spin in the magnetic field. Total energy and spin is
+conserved in the non-adiabatic process. Approaching the new local ground state
+is therefore accompanied by the emission of dispersive wave packets of
+excitations carrying energy and spin and propagating through the lattice with
+Fermi velocity. While the spin dynamics in the regime of strong exchange
+coupling J is rather complex and governed by an emergent new time scale, the
+motion of the spin for weak J is regular and qualitatively well described by
+the Landau-Lifschitz-Gilbert (LLG) equation. Quantitatively, however, the full
+quantum-classical hybrid dynamics differs from the LLG approach. This is
+understood as a breakdown of weak-coupling perturbation theory in J in the
+course of time. Furthermore, it is shown that the concept of the Gilbert
+damping parameter is ill-defined for the case of a one-dimensional system.",1507.08227v2
+2008-09-26,Damping and magnetic anisotropy of ferromagnetic GaMnAs thin films,"The magnetic properties of annealed, epitaxial Ga0.93Mn0.07As layers under
+tensile and compressive stress have been investigated by X-band (9GHz) and
+Q-band (35GHz) ferromagnetic resonance (FMR) spectroscopy. From the analysis of
+the linewidths of the uniform mode spectra the FMR Gilbert damping factor
+""alpha"" has been determined. At T=4K we obtain a minimum damping factor of
+""alpha"" = 0.003 for the compressively stressed layer. Its value is not
+isotropic. It has a minimum value for the easy axes orientations of the
+magnetic field and increases with the measuring temperature. Its average value
+is for both type of films of the order of 0.01 in spite of strong differences
+in the inhomogeneous linewidth which vary between 20 Oe and 600 Oe for the
+layers grown on GaAs and GaInAs substrates respectively.",0809.4644v2
+2013-08-02,Spin pumping damping and magnetic proximity effect in Pd and Pt spin-sink layers,"We investigated the spin pumping damping contributed by paramagnetic layers
+(Pd, Pt) in both direct and indirect contact with ferromagnetic
+Ni$_{81}$Fe$_{19}$ films. We find a nearly linear dependence of the
+interface-related Gilbert damping enhancement $\Delta\alpha$ on the heavy-metal
+spin-sink layer thicknesses t$_\textrm{N}$ in direct-contact
+Ni$_{81}$Fe$_{19}$/(Pd, Pt) junctions, whereas an exponential dependence is
+observed when Ni$_{81}$Fe$_{19}$ and (Pd, Pt) are separated by \unit[3]{nm} Cu.
+We attribute the quasi-linear thickness dependence to the presence of induced
+moments in Pt, Pd near the interface with Ni$_{81}$Fe$_{19}$, quantified using
+X-ray magnetic circular dichroism (XMCD) measurements. Our results show that
+the scattering of pure spin current is configuration-dependent in these systems
+and cannot be described by a single characteristic length.",1308.0450v2
+2015-02-05,Nonlinear analysis of magnetization dynamics excited by spin Hall effect,"We investigate the possibility of exciting self-oscillation in a
+perpendicular ferromagnet by the spin Hall effect on the basis of a nonlinear
+analysis of the Landau-Lifshitz-Gilbert (LLG) equation. In the self-oscillation
+state, the energy supplied by the spin torque during a precession on a constant
+energy curve should equal the dissipation due to damping. Also, the current to
+balance the spin torque and the damping torque in the self-oscillation state
+should be larger than the critical current to destabilize the initial state. We
+find that the second condition in the spin Hall system is not satisfied by
+deriving analytical solutions of the energy supplied by the spin transfer
+effect and the dissipation due to the damping from the nonlinear LLG equation.
+This indicates that the self-oscillation of a perpendicular ferromagnet cannot
+be excited solely by the spin Hall torque.",1502.01420v2
+2015-03-04,Critical current destabilizing perpendicular magnetization by the spin Hall effect,"The critical current needed to destabilize the magnetization of a
+perpendicular ferromagnet via the spin Hall effect is studied. Both the
+dampinglike and fieldlike torques associated with the spin current generated by
+the spin Hall effect is included in the Landau-Lifshitz-Gilbert equation to
+model the system. In the absence of the fieldlike torque, the critical current
+is independent of the damping constant and is much larger than that of
+conventional spin torque switching of collinear magnetic systems, as in
+magnetic tunnel junctions. With the fieldlike torque included, we find that the
+critical current scales with the damping constant as $\alpha^{0}$ (i.e.,
+damping independent),$\alpha$, and $\alpha^{1/2}$ depending on the sign of the
+fieldlike torque and other parameters such as the external field. Numerical and
+analytical results show that the critical current can be significantly reduced
+when the fieldlike torque possesses the appropriate sign, i.e. when the
+effective field associated with the fieldlike torque is pointing opposite to
+the spin direction of the incoming electrons. These results provide a pathway
+to reducing the current needed to switch magnetization using the spin Hall
+effect.",1503.01478v2
+2015-10-23,Laser-induced THz magnetization precession for a tetragonal Heusler-like nearly compensated ferrimagnet,"Laser-induced magnetization precessional dynamics was investigated in
+epitaxial films of Mn$_3$Ge, which is a tetragonal Heusler-like nearly
+compensated ferrimagnet. The ferromagnetic resonance (FMR) mode was observed,
+the precession frequency for which exceeded 0.5 THz and originated from the
+large magnetic anisotropy field of approximately 200 kOe for this ferrimagnet.
+The effective damping constant was approximately 0.03. The corresponding
+effective Landau-Lifshitz constant of approximately 60 Mrad/s and is comparable
+to those of the similar Mn-Ga materials. The physical mechanisms for the
+Gilbert damping and for the laser-induced excitation of the FMR mode were also
+discussed in terms of the spin-orbit-induced damping and the laser-induced
+ultrafast modulation of the magnetic anisotropy, respectively.",1510.06793v1
+2017-04-11,CoFeAlB alloy with low damping and low magnetization for spin transfer torque switching,"We investigate the effect of Al doping on the magnetic properties of the
+alloy CoFeB. Comparative measurements of the saturation magnetization, the
+Gilbert damping parameter $\alpha$ and the exchange constant as a function of
+the annealing temperature for CoFeB and CoFeAlB thin films are presented. Our
+results reveal a strong reduction of the magnetization for CoFeAlB in
+comparison to CoFeB. If the prepared CoFeAlB films are amorphous, the damping
+parameter $\alpha$ is unaffected by the Al doping in comparison to the CoFeB
+alloy. In contrast, in the case of a crystalline CoFeAlB film, $\alpha$ is
+found to be reduced. Furthermore, the x-ray characterization and the evolution
+of the exchange constant with the annealing temperature indicate a similar
+crystallization process in both alloys. The data proves the suitability of
+CoFeAlB for spin torque switching properties where a reduction of the switching
+current in comparison with CoFeB is expected.",1704.03326v1
+2018-09-25,"Theory of damping in magnetization dynamics, dispelling a myth and pointing a way forward","There is a widely-held belief amongst theoreticians that the Gilbert damping
+parameter {\alpha} in magnetization dynamics is infinite for a pure metal at
+T=0. The basic error leading to this belief is pointed out explicitly and the
+various methods of calculation used are viewed in a unified way based on the
+Lorentzian lineshape of ferromagnetic resonance spectra. A general torque
+formula for {\alpha} is proposed as a good starting-point for treating
+inhomogeneous materials such as alloys, compounds and layered structures. Local
+spin density functional theory provides a simple physical picture, in terms of
+a non-uniform precessional cone angle in ferromagnetic resonance, of how such
+inhomogeneity contributes to the damping. In a complementary many-body theory
+this contribution is given by a vertex correction to the torque-torque response
+function.",1809.09429v1
+2018-10-31,Anisotropic and controllable Gilbert-Bloch dissipation in spin valves,"Spin valves form a key building block in a wide range of spintronic concepts
+and devices from magnetoresistive read heads to spin-transfer-torque
+oscillators. We elucidate the dependence of the magnetic damping in the free
+layer on the angle its equilibrium magnetization makes with that in the fixed
+layer. The spin pumping-mediated damping is anisotropic and tensorial, with
+Gilbert- and Bloch-like terms. Our investigation reveals a mechanism for tuning
+the free layer damping in-situ from negligible to a large value via the
+orientation of fixed layer magnetization, especially when the magnets are
+electrically insulating. Furthermore, we expect the Bloch contribution that
+emerges from the longitudinal spin accumulation in the non-magnetic spacer to
+play an important role in a wide range of other phenomena in spin valves.",1811.00020v2
+2019-07-27,Two improved Gauss-Seidel projection methods for Landau-Lifshitz-Gilbert equation,"In this paper, we present two improved Gauss-Seidel projection methods with
+unconditional stability. The first method updates the gyromagnetic term and the
+damping term simultaneously and follows by a projection step. The second method
+introduces two sets of approximate solutions, where we update the gyromagnetic
+term and the damping term simultaneously for one set of approximate solutions
+and apply the projection step to the other set of approximate solutions in an
+alternating manner. Compared to the original Gauss-Seidel projection method
+which has to solve heat equations $7$ times at each time step, the improved
+methods solve heat equations $5$ times and $3$ times, respectively. First-order
+accuracy in time and second-order accuracy in space are verified by examples in
+both 1D and 3D. In addition, unconditional stability with respect to both the
+grid size and the damping parameter is confirmed numerically. Application of
+both methods to a realistic material is also presented with hysteresis loops
+and magnetization profiles. Compared with the original method, the recorded
+running times suggest that savings of both methods are about $2/7$ and $4/7$
+for the same accuracy requirement, respectively.",1907.11853v1
+2020-10-01,Modeling coupled spin and lattice dynamics,"A unified model of molecular and atomistic spin dynamics is presented
+enabling simulations both in microcanonical and canonical ensembles without the
+necessity of additional phenomenological spin damping. Transfer of energy and
+angular momentum between the lattice and the spin systems is achieved by a
+coupling term based upon the spin-orbit interaction. The characteristic spectra
+of the spin and phonon systems are analyzed for different coupling strength and
+temperatures. The spin spectral density shows magnon modes together with the
+uncorrelated noise induced by the coupling to the lattice. The effective
+damping parameter is investigated showing an increase with both coupling
+strength and temperature. The model paves the way to understanding magnetic
+relaxation processes beyond the phenomenological approach of the Gilbert
+damping and the dynamics of the energy transfer between lattice and spins.",2010.00642v1
+2021-04-22,Impact of Fe$_{80}$B$_{20}$ insertion on the properties of dual-MgO perpendicular magnetic tunnel junctions,"We explore the impact of Fe80B20 inserted at both
+Co$_{20}$Fe$_{80}$B$_{20}$/MgO interfaces of dual-MgO free layers (FLs) in
+bottom-pinned magnetic tunnel junctions (MTJs). MTJ stacks are annealed for 30
+min at 350 $^\circ$C and 400 $^\circ$C in a vacuum after film deposition.
+Current-in-plane tunneling measurements are carried out to characterize
+magnetotransport properties of the MTJs. Conventional magnetometry measurements
+and ferromagnetic resonance are conducted to estimate the saturation
+magnetization, the effective perpendicular anisotropy field and the Gilbert
+damping of dual-MgO FLs as a function of the Fe$_{80}$B$_{20}$ thickness and
+annealing temperatures. With ultrathin Fe$_{80}$B$_{20}$ (0.2 - 0.4 nm)
+inserted, perpendicular magnetic anisotropy (PMA) of FLs increases with similar
+tunnel magneto-resistance (TMR) and low damping values. As Fe$_{80}$B$_{20}$
+layer thickness further increases (0.6 - 1.2 nm), both TMR and PMA degrade, and
+damping increases dramatically. This study demonstrates a novel approach to
+tune properties of MTJ stacks with dual-MgO FLs up to 400 $^\circ$C annealing,
+which enables MTJ stacks for various applications.",2104.10918v1
+2021-09-24,Damping in yttrium iron garnet film with an interface,"We report strong damping enhancement in a 200 nm thick yttrium iron garnet
+(YIG) film due to spin inhomogeneity at the interface. The growth-induced thin
+interfacial gadolinium iron garnet (GdIG) layer antiferromagnetically (AFM)
+exchange couples with the rest of the YIG layer. The out-of-plane angular
+variation of ferromagnetic resonance (FMR) linewidth $\Delta H$ reflects a
+large inhomogeneous distribution of effective magnetization $\Delta 4 \pi
+M_{eff}$ due to the presence of an exchange springlike moments arrangement in
+YIG. We probe the spin inhomogeneity at the YIG-GdIG interface by performing an
+in-plane angular variation of resonance field $H_{r}$, leading to a
+unidirectional feature. The large extrinsic $\Delta 4\pi M_{eff}$ contribution,
+apart from the inherent intrinsic Gilbert contribution, manifests enhanced
+precessional damping in YIG film.",2109.12071v1
+2019-01-29,Bounding the spectral gap for an elliptic eigenvalue problem with uniformly bounded stochastic coefficients,"A key quantity that occurs in the error analysis of several numerical methods
+for eigenvalue problems is the distance between the eigenvalue of interest and
+the next nearest eigenvalue. When we are interested in the smallest or
+fundamental eigenvalue, we call this the spectral or fundamental gap. In a
+recent manuscript [Gilbert et al., arXiv:1808.02639], the current authors,
+together with Frances Kuo, studied an elliptic eigenvalue problem with
+homogeneous Dirichlet boundary conditions, and with coefficients that depend on
+an infinite number of uniformly distributed stochastic parameters. In this
+setting, the eigenvalues, and in turn the eigenvalue gap, also depend on the
+stochastic parameters. Hence, for a robust error analysis one needs to be able
+to bound the gap over all possible realisations of the parameters, and because
+the gap depends on infinitely-many random parameters, this is not trivial. This
+short note presents, in a simplified setting, an important result that was
+shown in the paper above. Namely, that, under certain decay assumptions on the
+coefficient, the spectral gap of such a random elliptic eigenvalue problem can
+be bounded away from 0, uniformly over the entire infinite-dimensional
+parameter space.",1901.10470v1
+2003-09-11,Theory of Current-Induced Magnetization Precession,"We solve appropriate drift-diffusion and Landau-Lifshitz-Gilbert equations to
+demonstrate that unpolarized current flow from a non-magnet into a ferromagnet
+can produce a precession-type instability of the magnetization. The fundamental
+origin of the instability is the difference in conductivity between majority
+spins and minority spins in the ferromagnet. This leads to spin accumulation
+and spin currents that carry angular momentum across the interface. The
+component of this angular momentum perpendicular to the magnetization drives
+precessional motion that is opposed by Gilbert damping. Neglecting magnetic
+anisotropy and magnetostatics, our approximate analytic and exact numerical
+solutions using realistic values for the material parameters show (for both
+semi-infinite and thin film geometries) that a linear instability occurs when
+both the current density and the excitation wave vector parallel to the
+interface are neither too small nor too large. For many aspects of the problem,
+the variation of the magnetization in the direction of the current flows makes
+an important contribution.",0309289v1
+2005-07-20,All-optical probe of precessional magnetization dynamics in exchange biased NiFe/FeMn bilayers,"An internal anisotropy pulse field is launched by an 8.3 ps short laser
+excitation, which triggers precessional magnetization dynamics of a
+polycrystalline NiFe/FeMn exchange bias system on the picosecond timescale. Due
+to the excitation the unidirectional anisotropy and, thus, the exchange
+coupling across the interface between the ferromagnetic and the
+antiferromagnetic layer is reduced, leading to a fast reduction of the exchange
+bias field and to a dramatic increase of the zero-field susceptibility. The
+fast optical unpinning is followed by a slower recovery of the interfacial
+exchange coupling dominated by spin-lattice and heat flow relaxation with a
+time constant of the order of 160 ps. The measured picosecond time evolution of
+the exchange decoupling and restoration is interpreted as an anisotropy pulse
+field giving rise to fast precessional magnetization dynamics of the
+ferromagnetic layer. The strength of the internal pulse field and even the
+initial magnetization deflection direction from the equilibrium orientation can
+be controlled by the absorbed photons. The dependence of the effective Gilbert
+damping on both small and large angle precessional motion was studied, yielding
+that both cases can be modeled with reasonable accuracy within the
+Landau-Lifshitz and Gilbert framework.",0507475v1
+2009-05-28,Hydrodynamic theory of coupled current and magnetization dynamics in spin-textured ferromagnets,"We develop the hydrodynamical theory of collinear spin currents coupled to
+magnetization dynamics in metallic ferromagnets. The collective spin density
+couples to the spin current through a U(1) Berry-phase gauge field determined
+by the local texture and dynamics of the magnetization. We determine
+phenomenologically the dissipative corrections to the equation of motion for
+the electronic current, which consist of a dissipative spin-motive force
+generated by magnetization dynamics and a magnetic texture-dependent
+resistivity tensor. The reciprocal dissipative, adiabatic spin torque on the
+magnetic texture follows from the Onsager principle. We investigate the effects
+of thermal fluctuations and find that electronic dynamics contribute to a
+nonlocal Gilbert damping tensor in the Landau-Lifshitz-Gilbert equation for the
+magnetization. Several simple examples, including magnetic vortices, helices,
+and spirals, are analyzed in detail to demonstrate general principles.",0905.4544v2
+2010-11-26,Dependence of nonlocal Gilbert damping on the ferromagnetic layer type in FM/Cu/Pt heterostructures,"We have measured the size effect in nonlocal Gilbert relaxation rate in
+FM(t$_{FM}$) / Cu (5nm) [/ Pt (2nm)] / Al(2nm) heterostructures, FM = \{
+Ni$_{81}$Fe$_{19}$, Co$_{60}$Fe$_{20}$B$_{20}$, pure Co\}. Common behavior is
+observed for three FM layers, where the additional relaxation obeys both a
+strict inverse power law dependence $\Delta G =K \:t^{n}$,
+$n=-\textrm{1.04}\pm\textrm{0.06}$ and a similar magnitude
+$K=\textrm{224}\pm\textrm{40 Mhz}\cdot\textrm{nm}$. As the tested FM layers
+span an order of magnitude in spin diffusion length $\lambda_{SDL}$, the
+results are in support of spin diffusion, rather than nonlocal resistivity, as
+the origin of the effect.",1011.5868v1
+2012-06-21,Fast domain wall propagation in uniaxial nanowires with transverse fields,"Under a magnetic field along its axis, domain wall motion in a uniaxial
+nanowire is much slower than in the fully anisotropic case, typically by
+several orders of magnitude (the square of the dimensionless Gilbert damping
+parameter). However, with the addition of a magnetic field transverse to the
+wire, this behaviour is dramatically reversed; up to a critical field strength,
+analogous to the Walker breakdown field, domain walls in a uniaxial wire
+propagate faster than in a fully anisotropic wire (without transverse field).
+Beyond this critical field strength, precessional motion sets in, and the mean
+velocity decreases. Our results are based on leading-order analytic
+calculations of the velocity and critical field as well as numerical solutions
+of the Landau-Lifshitz-Gilbert equation.",1206.4819v2
+2013-03-05,"Angle-Dependent Spin-Wave Resonance Spectroscopy of (Ga,Mn)As Films","A modeling approach for standing spin-wave resonances based on a
+finite-difference formulation of the Landau-Lifshitz-Gilbert equation is
+presented. In contrast to a previous study [Bihler et al., Phys. Rev. B 79,
+045205 (2009)], this formalism accounts for elliptical magnetization precession
+and magnetic properties arbitrarily varying across the layer thickness,
+including the magnetic anisotropy parameters, the exchange stiffness, the
+Gilbert damping, and the saturation magnetization. To demonstrate the
+usefulness of our modeling approach, we experimentally study a set of (Ga,Mn)As
+samples grown by low-temperature molecular-beam epitaxy by means of
+electrochemical capacitance-voltage measurements and angle-dependent standing
+spin-wave resonance spectroscopy. By applying our modeling approach, the angle
+dependence of the spin-wave resonance data can be reproduced in a simulation
+with one set of simulation parameters for all external field orientations. We
+find that the approximately linear gradient in the out-of-plane magnetic
+anisotropy is related to a linear gradient in the hole concentrations of the
+samples.",1303.1192v1
+2013-04-26,Landau-Lifshitz theory of the longitudinal spin Seebeck effect,"Thermal-bias-induced spin angular momentum transfer between a paramagnetic
+metal and ferromagnetic insulator is studied theoretically based on the
+stochastic Landau-Lifshitz-Gilbert (LLG) phenomenology. Magnons in the
+ferromagnet establish a nonequilibrium steady state by equilibrating with
+phonons via bulk Gilbert damping and electrons in the paramagnet via spin
+pumping, according to the fluctuation-dissipation theorem. Subthermal magnons
+and the associated spin currents are treated classically, while the appropriate
+quantum crossover is imposed on high-frequency magnetic fluctuations. We
+identify several length scales in the ferromagnet, which govern qualitative
+changes in the dependence of the thermally-induced spin current on the magnetic
+film thickness.",1304.7295v2
+2013-09-21,Patterns formation in axially symmetric Landau-Lifshitz-Gilbert-Slonczewski equations,"The Landau-Lifshitz-Gilbert-Slonczewski equation describes magnetization
+dynamics in the presence of an applied field and a spin polarized current. In
+the case of axial symmetry and with focus on one space dimension, we
+investigate the emergence of space-time patterns in the form of wavetrains and
+coherent structures, whose local wavenumber varies in space. A major part of
+this study concerns existence and stability of wavetrains and of front- and
+domain wall-type coherent structures whose profiles asymptote to wavetrains or
+the constant up-/down-magnetizations. For certain polarization the Slonczewski
+term can be removed which allows for a more complete charaterization, including
+soliton-type solutions. Decisive for the solution structure is the polarization
+parameter as well as size of anisotropy compared with the difference of field
+intensity and current intensity normalized by the damping.",1309.5523v4
+2014-02-27,On the longitudinal spin current induced by a temperature gradient in a ferromagnetic insulator,"Based on the solution of the stochastic Landau-Lifshitz-Gilbert equation
+discretized for a ferromagnetic chain subject to a uniform temperature
+gradient, we present a detailed numerical study of the spin dynamics with a
+focus particularly on finite-size effects. We calculate and analyze the net
+longitudinal spin current for various temperature gradients, chain lengths, and
+external static magnetic fields. In addition, we model an interface formed by a
+nonuniformly magnetized finite-size ferromagnetic insulator and a normal metal
+and inspect the effects of enhanced Gilbert damping on the formation of the
+space-dependent spin current within the chain. A particular aim of this study
+is the inspection of the spin Seebeck effect beyond the linear response regime.
+We find that within our model the microscopic mechanism of the spin Seebeck
+current is the magnon accumulation effect quantified in terms of the exchange
+spin torque. According to our results, this effect drives the spin Seebeck
+current even in the absence of a deviation between the magnon and phonon
+temperature profiles. Our theoretical findings are in line with the recently
+observed experimental results by M. Agrawal et al., Phys. Rev. Lett. 111,
+107204 (2013).",1402.6899v1
+2015-01-19,Effect of Exchange Interaction on Magnetic Thermal Fluctuation and Spin Susceptibility,"The expression of the thermal fluctuation parameter in the stochastic
+Landau-Lifshitz-Gilbert equation has been derived from a fundamental quantum
+theory of spins and phonons, in which the exchange interaction between nearest
+atoms has been included. Our studies show that the thermal fluctuation
+decreases exponentially with increasing exchange interaction. The non-uniform
+fluctuation of local spins make the spin susceptibility much different from the
+result derived by the macro-spin model or single spin model. The related spin
+susceptibility depends not only on the strength of exchange interaction, but
+also on the lattice structure. The non-uniform fluctuation can lead to an extra
+broadening of the resonance line width along with the broadening arisen from
+the Gilbert damping.",1501.04503v2
+2015-07-23,Nanomagnet coupled to quantum spin Hall edge: An adiabatic quantum motor,"The precessing magnetization of a magnetic islands coupled to a quantum spin
+Hall edge pumps charge along the edge. Conversely, a bias voltage applied to
+the edge makes the magnetization precess. We point out that this device
+realizes an adiabatic quantum motor and discuss the efficiency of its operation
+based on a scattering matrix approach akin to Landauer-B""uttiker theory.
+Scattering theory provides a microscopic derivation of the
+Landau-Lifshitz-Gilbert equation for the magnetization dynamics of the device,
+including spin-transfer torque, Gilbert damping, and Langevin torque. We find
+that the device can be viewed as a Thouless motor, attaining unit efficiency
+when the chemical potential of the edge states falls into the
+magnetization-induced gap. For more general parameters, we characterize the
+device by means of a figure of merit analogous to the ZT value in
+thermoelectrics.",1507.06505v2
+2017-03-28,Temperature dependent magnetic damping of yttrium iron garnet spheres,"We investigate the temperature dependent microwave absorption spectrum of an
+yttrium iron garnet sphere as a function of temperature (5 K to 300 K) and
+frequency (3 GHz to 43.5 GHz). At temperatures above 100 K, the magnetic
+resonance linewidth increases linearly with temperature and shows a
+Gilbert-like linear frequency dependence. At lower temperatures, the
+temperature dependence of the resonance linewidth at constant external magnetic
+fields exhibits a characteristic peak which coincides with a non-Gilbert-like
+frequency dependence. The complete temperature and frequency evolution of the
+linewidth can be modeled by the phenomenology of slowly relaxing rare-earth
+impurities and either the Kasuya-LeCraw mechanism or the scattering with
+optical magnons. Furthermore, we extract the temperature dependence of the
+saturation magnetization, the magnetic anisotropy and the g-factor.",1703.09444v2
+2017-12-10,Magnetic field gradient driven dynamics of isolated skyrmions and antiskyrmions in frustrated magnets,"The study of skyrmion/antiskyrmion motion in magnetic materials is very
+important in particular for the spintronics applications. In this work, we
+study the dynamics of isolated skyrmions and antiskyrmions in frustrated
+magnets driven by magnetic field gradient, using the Landau-Lifshitz-Gilbert
+simulations on the frustrated classical Heisenberg model on the triangular
+lattice. A Hall-like motion induced by the gradient is revealed in bulk system,
+similar to that in the well-studied chiral magnets. More interestingly, our
+work suggests that the lateral confinement in nano-stripes of the frustrated
+system can completely suppress the Hall motion and significantly speed up the
+motion along the gradient direction. The simulated results are well explained
+by the Thiele theory. It is demonstrated that the acceleration of the motion is
+mainly determined by the Gilbert damping constant, which provides useful
+information for finding potential materials for skyrmion-based spintronics.",1712.03550v1
+2018-02-28,Roles of chiral renormalization on magnetization dynamics in chiral magnets,"In metallic ferromagnets, the interaction between local magnetic moments and
+conduction electrons renormalizes parameters of the Landau-Lifshitz-Gilbert
+equation such as the gyromagnetic ratio and the Gilbert damping, and makes them
+dependent on the magnetic configurations. Although the effects of the
+renormalization for nonchiral ferromagnets are usually minor and hardly
+detectable, we show that the renormalization does play a crucial role for
+chiral magnets. Here the renormalization is chiral and as such we predict
+experimentally identifiable effects on the phenomenology of magnetization
+dynamics. In particular, our theory for the self-consistent magnetization
+dynamics of chiral magnets allows for a concise interpretation of domain wall
+creep motion. We also argue that the conventional creep theory of the domain
+wall motion, which assumes Markovian dynamics, needs critical reexamination
+since the gyromagnetic ratio makes the motion non-Markovian. The non-Markovian
+nature of the domain wall dynamics is experimentally checkable by the chirality
+of the renormalization.",1803.00017v2
+2018-12-20,Laser Controlled Spin Dynamics of Ferromagnetic Thin Film from Femtosecond to Nanosecond Timescale,"Laser induced modulation of the magnetization dynamics occurring over various
+time-scales have been unified here for a Ni80Fe20 thin film excited by
+amplified femtosecond laser pulses. The weak correlation between
+demagnetization time and pump fluence with substantial enhancement in
+remagnetization time is demonstrated using three-temperature model considering
+the temperatures of electron, spin and lattice. The picosecond magnetization
+dynamics is modeled using the Landau-Lifshitz-Gilbert equation. With increasing
+pump fluence the Gilbert damping parameter shows significant enhancement from
+its intrinsic value due to increment in the ratio of electronic temperature to
+Curie temperature within very short time scale. The precessional frequency
+experiences noticeable red shift with increasing pump fluence. The changes in
+the local magnetic properties due to accumulation and dissipation of thermal
+energy within the probed volume are described by the evolution of temporal
+chirp parameter in a comprehensive manner. A unification of ultrafast magnetic
+processes and its control over broad timescale would enable the integration of
+various magnetic processes in a single device and use one effect to control
+another.",1812.08404v1
+2019-03-13,Higher-order linearly implicit full discretization of the Landau--Lifshitz--Gilbert equation,"For the Landau--Lifshitz--Gilbert (LLG) equation of micromagnetics we study
+linearly implicit backward difference formula (BDF) time discretizations up to
+order $5$ combined with higher-order non-conforming finite element space
+discretizations, which are based on the weak formulation due to Alouges but use
+approximate tangent spaces that are defined by $L^2$-averaged instead of nodal
+orthogonality constraints. We prove stability and optimal-order error bounds in
+the situation of a sufficiently regular solution. For the BDF methods of orders
+$3$ to~$5$, this requires %a mild time step restriction $\tau \leqslant ch$ and
+that the damping parameter in the LLG equations be above a positive threshold;
+this condition is not needed for the A-stable methods of orders $1$ and $2$,
+for which furthermore a discrete energy inequality irrespective of solution
+regularity is proved.",1903.05415v2
+2019-12-01,Coarse-graining in micromagnetic simulations of dynamic hysteresis loops,"Micromagnetic simulations based on the stochastic Landau-Lifshitz-Gilbert
+equation are used to calculate dynamic magnetic hysteresis loops relevant to
+magnetic hyperthermia. With the goal to effectively simulate room-temperature
+loops for large iron-oxide-based systems at relatively slow sweep rates on the
+order of 1 Oe/ns or less, a previously derived renormalization group approach
+for coarse-graining (Grinstein and Koch, Phys. Rev. Lett. 20, 207201, 2003) is
+modified and applied to calculating loops for a magnetite nanorod. The nanorod
+modelled is the building block for larger nanoparticles that were employed in
+preclinical studies (Dennis et al., Nanotechnology 20, 395103, 2009). The
+scaling algorithm is shown to produce nearly identical loops over several
+decades in the model grain size. Sweep-rate scaling involving the Gilbert
+damping parameter is also demonstrated to allow orders of magnitude speed-up of
+the loop calculations.",1912.00310v3
+2020-02-17,Self-similar shrinkers of the one-dimensional Landau-Lifshitz-Gilbert equation,"The main purpose of this paper is the analytical study of self-shrinker
+solutions of the one-dimensional Landau-Lifshitz-Gilbert equation (LLG), a
+model describing the dynamics for the spin in ferromagnetic materials. We show
+that there is a unique smooth family of backward self-similar solutions to the
+LLG equation, up to symmetries, and we establish their asymptotics. Moreover,
+we obtain that in the presence of damping, the trajectories of the self-similar
+profiles converge to great circles on the sphere $\mathbb{S}^2$, at an
+exponential rate. In particular, the results presented in this paper provide
+examples of blow-up in finite time, where the singularity develops due to rapid
+oscillations forming limit circles.",2002.06858v2
+2021-02-20,Fast magnetization reversal of a magnetic nanoparticle induced by cosine chirp microwave field pulse,"We investigate the magnetization reversal of single-domain magnetic
+nanoparticle driven by the circularly polarized cosine chirp microwave pulse
+(CCMP). The numerical findings, based on the Landau-Lifshitz-Gilbert equation,
+reveal that the CCMP is by itself capable of driving fast and energy-efficient
+magnetization reversal. The microwave field amplitude and initial frequency
+required by a CCMP are much smaller than that of the linear down-chirp
+microwave pulse. This is achieved as the frequency change of the CCMP closely
+matches the frequency change of the magnetization precession which leads to an
+efficient stimulated microwave energy absorption (emission) by (from) the
+magnetic particle before (after) it crosses over the energy barrier. We further
+find that the enhancement of easy-plane shape anisotropy significantly reduces
+the required microwave amplitude and the initial frequency of CCMP. We also
+find that there is an optimal Gilbert damping for fast magnetization reversal.
+These findings may provide a pathway to realize the fast and low-cost memory
+device.",2102.10394v2
+2021-07-24,Electron-Phonon Scattering governs both Ultrafast and Precessional Magnetization Dynamics in Co-Fe Alloys,"Recent investigations have advanced the understanding of how
+structure-property relationships in ferromagnetic metal alloys affect the
+magnetization dynamics on nanosecond time-scales. A similar understanding for
+magnetization dynamics on femto- to pico-second time-scales does not yet exist.
+To address this, we perform time-resolved magneto optic Kerr effect (TRMOKE)
+measurements of magnetization dynamics in Co-Fe alloys on femto- to nano-second
+regimes. We show that Co-Fe compositions that exhibit low Gilbert damping
+parameters also feature prolonged ultrafast demagnetization upon
+photoexcitation. We analyze our experimental TR-MOKE data with the
+three-temperature-model (3TM) and the Landau-Lifshitz-Gilbert equation. These
+analyses reveal a strong compositional dependence of the dynamics across all
+time-scales on the strength of electron-phonon interactions. Our findings are
+beneficial to the spintronics and magnonics community, and will aid in the
+quest for energy-efficient magnetic storage applications.",2107.11699v1
+2022-09-07,Convergence analysis of an implicit finite difference method for the inertial Landau-Lifshitz-Gilbert equation,"The Landau-Lifshitz-Gilbert (LLG) equation is a widely used model for fast
+magnetization dynamics in ferromagnetic materials. Recently, the inertial LLG
+equation, which contains an inertial term, has been proposed to capture the
+ultra-fast magnetization dynamics at the sub-picosecond timescale.
+Mathematically, this generalized model contains the first temporal derivative
+and a newly introduced second temporal derivative of magnetization.
+Consequently, it produces extra difficulties in numerical analysis due to the
+mixed hyperbolic-parabolic type of this equation with degeneracy. In this work,
+we propose an implicit finite difference scheme based on the central difference
+in both time and space. A fixed point iteration method is applied to solve the
+implicit nonlinear system. With the help of a second order accurate constructed
+solution, we provide a convergence analysis in $H^1$ for this numerical scheme,
+in the $\ell^\infty (0, T; H_h^1)$ norm. It is shown that the proposed method
+is second order accurate in both time and space, with unconditional stability
+and a natural preservation of the magnetization length. In the hyperbolic
+regime, significant damping wave behaviors of magnetization at a shorter
+timescale are observed through numerical simulations.",2209.02914v2
+2022-09-16,Pseudo-PT symmetric Dirac equation : effect of a new mean spin angular momentum operator on Gilbert damping,"The pseudo-PT symmetric Dirac equation is proposed and analyzed by using a
+non-unitary Foldy-Wouthuysen transformations. A new spin operator PT symmetric
+expectation value (called the mean spin operator) for an electron interacting
+with a time-dependent electromagnetic field is obtained. We show that spin
+magnetization - which is the quantity usually measured experimentally - is not
+described by the standard spin operator but by this new mean spin operator to
+properly describe magnetization dynamics in ferromagnetic materials and the
+corresponding equation of motion is compatible with the phenomenological model
+of the Landau-Lifshitz-Gilbert equation (LLG).",2209.07908v1
+2022-11-15,Nonlinear sub-switching regime of magnetization dynamics in photo-magnetic garnets,"We analyze, both experimentally and numerically, the nonlinear regime of the
+photo-induced coherent magnetization dynamics in cobalt-doped yttrium iron
+garnet films. Photo-magnetic excitation with femtosecond laser pulses reveals a
+strongly nonlinear response of the spin subsystem with a significant increase
+of the effective Gilbert damping. By varying both laser fluence and the
+external magnetic field, we show that this nonlinearity originates in the
+anharmonicity of the magnetic energy landscape. We numerically map the
+parameter workspace for the nonlinear photo-induced spin dynamics below the
+photo-magnetic switching threshold. Corroborated by numerical simulations of
+the Landau-Lifshitz-Gilbert equation, our results highlight the key role of the
+cubic symmetry of the magnetic subsystem in reaching the nonlinear spin
+precession regime. These findings expand the fundamental understanding of
+laser-induced nonlinear spin dynamics as well as facilitate the development of
+applied photo-magnetism.",2211.08048v2
+2023-08-16,Discovery and regulation of chiral magnetic solitons: Exact solution from Landau-Lifshitz-Gilbert equation,"The Landau-Lifshitz-Gilbert (LLG) equation has emerged as a fundamental and
+indispensable framework within the realm of magnetism. However, solving the LLG
+equation, encompassing full nonlinearity amidst intricate complexities,
+presents formidable challenges. In this context, we develop a precise mapping
+through geometric representation, establishing a direct linkage between the LLG
+equation and an integrable generalized nonlinear Schr\""odinger equation. This
+novel mapping provides accessibility towards acquiring a great number of exact
+spatiotemporal solutions. Notably, exact chiral magnetic solitons, critical for
+stability and controllability in propagation with and without damping effects
+are discovered. Our formulation provides exact solutions for the long-standing
+fully nonlinear problem, facilitating practical control through spin current
+injection in magnetic memory applications.",2308.08331v1
+1997-07-20,Effects of gluon damping rate on the viscosity coefficient of the quark-gluon plasma at finite chemical potential,"By considering the Debye screening and damping rate of gluons, the viscosity
+coefficient of the quark-gluon plasma was evaluated via real-time finite
+temperature QCD in the relaxation time approximation at finite temperature and
+chemical potential . The results show that both the damping rate and the
+chemical potential cause considerable enhancements to the viscosity coefficient
+of hot dense quark-gluon plasma.",9707033v1
+2015-07-04,Comments on turbulence theory by Qian and by Edwards and McComb,"We reexamine Liouville equation based turbulence theories proposed by Qian
+{[}Phys. Fluids \textbf{26}, 2098 (1983){]} and Edwards and McComb {[}J. Phys.
+A: Math. Gen. \textbf{2}, 157 (1969){]}, which are compatible with Kolmogorov
+spectrum. These theories obtained identical equation for spectral density
+$q(k)$ and different results for damping coefficient. Qian proposed variational
+approach and Edwards and McComb proposed maximal entropy principle to obtain
+equation for the damping coefficient. We show that assumptions used in these
+theories to obtain damping coefficient correspond to unphysical conditions.",1507.01124v1
+2018-10-14,Critical exponent for nonlinear damped wave equations with non-negative potential in 3D,"We are studying possible interaction of damping coefficients in the
+subprincipal part of the linear 3D wave equation and their impact on the
+critical exponent of the corresponding nonlinear Cauchy problem with small
+initial data. The main new phenomena is that certain relation between these
+coefficients may cause very strong jump of the critical Strauss exponent in 3D
+to the critical 5D Strauss exponent for the wave equation without damping
+coefficients.",1810.05956v1
+2021-01-23,Oscillation time and damping coefficients in a nonlinear pendulum,"We establish a relationship between the normalized damping coefficients and
+the time that takes a nonlinear pendulum to complete one oscillation starting
+from an initial position with vanishing velocity. We establish some conditions
+on the nonlinear restitution force so that this oscillation time does not
+depend monotonically on the viscosity damping coefficient.",2101.09400v2
+2024-03-26,On a class of nonautonomous quasilinear systems with general time-gradually-degenerate damping,"In this paper, we study two systems with a time-variable coefficient and
+general time-gradually-degenerate damping. More explicitly, we construct the
+Riemann solutions to the time-variable coefficient Zeldovich approximation and
+time-variable coefficient pressureless gas systems both with general
+time-gradually-degenerate damping. Applying the method of similar variables and
+nonlinear viscosity, we obtain classical Riemann solutions and delta shock wave
+solutions.",2403.17732v1
+2013-11-14,The dimension of the leafwise reduced cohomology,"Geometric conditions are given so that the leafwise reduced cohomology is of
+infinite dimension, specially for foliations with dense leaves on closed
+manifolds. The main new definition involved is the intersection number of
+subfoliations with ""appropriate coefficients"". The leafwise reduced cohomology
+is also described for homogeneous foliations with dense leaves on closed
+nilmanifolds.",1311.3518v1
+2002-12-05,Dynamic stiffness of spin valves,"The dynamics of the magnetic order parameters of
+ferromagnet/normal-metal/ferromagnet spin valves and isolated ferromagnets may
+be very different. We investigate the role of the nonequilibrium spin-current
+exchange between the ferromagnets in the magnetization precession and
+switching. We find a (low-temperature) critical current bias for a coherent
+current-induced magnetization excitation in spin valves, which unifies and
+generalizes previous ideas of Slonczewski and Berger. In the absence of an
+applied bias, the effect of the spin transfer can be expressed as
+magnetic--configuration-dependent Gilbert damping.",0212130v2
+2005-01-13,Magnetization noise in magnetoelectronic nanostructures,"By scattering theory we show that spin current noise in normal electric
+conductors in contact with nanoscale ferromagnets increases the magnetization
+noise by means of a fluctuating spin-transfer torque. Johnson-Nyquist noise in
+the spin current is related to the increased Gilbert damping due to spin
+pumping, in accordance with the fluctuation-dissipation theorem. Spin current
+shot noise in the presence of an applied bias is the dominant contribution to
+the magnetization noise at low temperatures.",0501318v1
+2005-01-27,Current-induced macrospin vs spin-wave excitations in spin valves,"The mode dependence of current-induced magnetic excitations in spin valves is
+studied theoretically. The torque exerted on the magnetization by transverse
+spin currents as well as the Gilbert damping constant are found to depend
+strongly on the wave length of the excitation (spin wave). Analytic expressions
+are presented for the critical currents that excite a selected spin wave. The
+onset of macrospin (zero wavelength) vs finite wavelength instabilities depends
+on the device parameters and the current direction, in agreement with recent
+experimental findings.",0501672v3
+2006-05-08,Microscopic Calculation of Spin Torques in Disordered Ferromagnets,"Effects of conduction electrons on magnetization dynamics, represented by
+spin torques, are calculated microscopically in the first order in spatial
+gradient and time derivative of magnetization. Special attention is paid to the
+so-called $\beta$-term and the Gilbert damping, $\alpha$, in the presence of
+electrons' spin-relaxation processes, which are modeled by quenched magnetic
+(and spin-orbit) impurities. The obtained results such as $\alpha \ne \beta$
+hold for localized as well as itinerant ferromagnetism.",0605186v1
+2006-11-27,Microscopic Calculation of Spin Torques and Forces,"Spin torques, that is, effects of conduction electrons on magnetization
+dynamics, are calculated microscopically in the first order in spatial gradient
+and time derivative of magnetization. Special attention is paid to the
+so-called \beta-term and the Gilbert damping, \alpha, in the presence of
+electrons' spin-relaxation processes, which are modeled by quenched magnetic
+impurities. Two types of forces that the electric/spin current exerts on
+magnetization are identified based on a general formula relating the force to
+the torque.",0611669v1
+2007-10-15,Ferromagnetic resonance study of polycrystalline Fe_{1-x}V_x alloy thin films,"Ferromagnetic resonance has been used to study the magnetic properties and
+magnetization dynamics of polycrystalline Fe$_{1-x}$V$_{x}$ alloy films with
+$0\leq x < 0.7$. Films were produced by co-sputtering from separate Fe and V
+targets, leading to a composition gradient across a Si substrate. FMR studies
+were conducted at room temperature with a broadband coplanar waveguide at
+frequencies up to 50 GHz using the flip-chip method. The effective
+demagnetization field $4 \pi M_{\mathrm{eff}}$ and the Gilbert damping
+parameter $\alpha$ have been determined as a function of V concentration. The
+results are compared to those of epitaxial FeV films.",0710.2826v2
+2008-10-25,The domain wall spin torque-meter,"We report the direct measurement of the non-adiabatic component of the
+spin-torque in domain walls. Our method is independent of both the pinning of
+the domain wall in the wire as well as of the Gilbert damping parameter. We
+demonstrate that the ratio between the non-adiabatic and the adiabatic
+components can be as high as 1, and explain this high value by the importance
+of the spin-flip rate to the non-adiabatic torque. Besides their fundamental
+significance these results open the way for applications by demonstrating a
+significant increase of the spin torque efficiency.",0810.4633v1
+2008-12-03,Observation of ferromagnetic resonance in strontium ruthenate (SrRuO3),"We report the observation of ferromagnetic resonance (FMR) in SrRuO3 using
+the time-resolved magneto-optical Kerr effect. The FMR oscillations in the
+time-domain appear in response to a sudden, optically induced change in the
+direction of easy-axis anistropy. The high FMR frequency, 250 GHz, and large
+Gilbert damping parameter, alpha ~ 1, are consistent with strong spin-orbit
+coupling. We find that the parameters associated with the magnetization
+dynamics, including alpha, have a non-monotonic temperature dependence,
+suggestive of a link to the anomalous Hall effect.",0812.0832v1
+2011-02-26,Dynamics of Skyrmion Crystals in Metallic Thin Films,"We study the collective dynamics of the Skyrmion crystal (SkX) in thin films
+of ferromagnetic metals resulting from the nontrivial Skyrmion topology. We
+show that the current-driven motion of the crystal reduces the topological Hall
+effect and the Skyrmion trajectories bend away from the direction of the
+electric current (the Skyrmion Hall effect). We find a new dissipation
+mechanism in non-collinear spin textures that can lead to a much faster spin
+relaxation than Gilbert damping, calculate the dispersion of phonons in the
+SkX, and discuss effects of impurity pinning of Skyrmions.",1102.5384v2
+2011-04-15,Lagrangian approach and dissipative magnetic systems,"A Lagrangian is introduced which includes the coupling between magnetic
+moments $\mathbf{m}$ and the degrees of freedom $\boldsymbol{\sigma}$ of a
+reservoir. In case the system-reservoir coupling breaks the time reversal
+symmetry the magnetic moments perform a damped precession around an effective
+field which is self-organized by the mutual interaction of the moments. The
+resulting evolution equation has the form of the Landau-Lifshitz-Gilbert
+equation. In case the bath variables are constant vector fields the moments
+$\mathbf{m}$ fulfill the reversible Landau-Lifshitz equation. Applying
+Noether's theorem we find conserved quantities under rotation in space and
+within the configuration space of the moments.",1104.3002v1
+2011-07-04,Minimization of the Switching Time of a Synthetic Free Layer in Thermally Assisted Spin Torque Switching,"We theoretically studied the thermally assisted spin torque switching of a
+synthetic free layer and showed that the switching time is minimized if the
+condition H_J=|H_s|/(2 alpha) is satisfied, where H_J, H_s and alpha are the
+coupling field of two ferromagnetic layers, the amplitude of the spin torque,
+and the Gilbert damping constant. We also showed that the coupling field of the
+synthetic free layer can be determined from the resonance frequencies of the
+spin-torque diode effect.",1107.0753v2
+2012-09-14,Skyrmion Dynamics in Multiferroic Insulator,"Recent discovery of Skyrmion crystal phase in insulating multiferroic
+compound Cu$_2$OSeO$_3$ calls for new ways and ideas to manipulate the
+Skyrmions in the absence of spin transfer torque from the conduction electrons.
+It is shown here that the position-dependent electric field, pointed along the
+direction of the average induced dipole moment of the Skyrmion, can induce the
+Hall motion of Skyrmion with its velocity orthogonal to the field gradient.
+Finite Gilbert damping produces longitudinal motion. We find a rich variety of
+resonance modes excited by a.c. electric field.",1209.3120v1
+2013-03-12,Thermally excited spin waves in a nano-structure: thermal gradient vs. constant temperature,"Using micromagnetic simulations, we have investigated spin dynamics in a
+nanostructure in the presence of thermal fluctuations. In particular, we have
+studied the effects of a uniform temperature and of a uniform thermal gradient.
+In both cases, the stochastic field leads to an increase of the precession
+angle of the magnetization, and to a mild decreas of the linewidth of the
+resonance peaks. Our results indicate that the Gilbert damping parameter plays
+the role of control parameter for the amplification of spin waves.",1303.2895v1
+2013-07-29,Theoretical Study of Spin-Torque Oscillator with Perpendicularly Magnetized Free Layer,"The magnetization dynamics of spin torque oscillator (STO) consisting of a
+perpendicularly magnetized free layer and an in-plane magnetized pinned layer
+was studied by solving the Landau-Lifshitz-Gilbert equation. We derived the
+analytical formula of the relation between the current and the oscillation
+frequency of the STO by analyzing the energy balance between the work done by
+the spin torque and the energy dissipation due to the damping. We also found
+that the field-like torque breaks the energy balance, and change the
+oscillation frequency.",1307.7427v1
+2014-06-10,Influence of Ta insertions on the magnetic properties of MgO/CoFeB/MgO films probed by ferromagnetic resonance,"We show by vector network analyzer ferromagnetic resonance measurements that
+low Gilbert damping {\alpha} down to 0.006 can be achieved in perpendicularly
+magnetized MgO/CoFeB/MgO thin films with ultra-thin insertions of Ta in the
+CoFeB layer. While increasing the number of Ta insertions allows thicker CoFeB
+layers to remain perpendicular, the effective areal magnetic anisotropy does
+not improve with more insertions, and also comes with an increase in {\alpha}.",1406.2491v2
+2014-09-24,Dissipationless Multiferroic Magnonics,"We propose that the magnetoelectric effect in multiferroic insulators with
+coplanar antiferromagnetic spiral order, such as BiFeO$_{3}$, enables
+electrically controlled dissipationless magnonics. Applying an oscillating
+electric field in these materials with frequency as low as household frequency
+can activate Goldstone modes that manifests fast planar rotations of spins,
+whose motion is not obstructed by crystalline anisotropy. Combining with spin
+ejection mechanisms, such a fast planar rotation can deliver electricity at
+room temperature over a distance of the magnetic domain, which is free from the
+energy loss due to Gilbert damping.",1409.6900v2
+2015-02-09,Large amplitude oscillation of magnetization in spin-torque oscillator stabilized by field-like torque,"Oscillation frequency of spin torque oscillator with a perpendicularly
+magnetized free layer and an in-plane magnetized pinned layer is theoretically
+investigated by taking into account the field-like torque. It is shown that the
+field-like torque plays an important role in finding the balance between the
+energy supplied by the spin torque and the dissipation due to the damping,
+which results in a steady precession. The validity of the developed theory is
+confirmed by performing numerical simulations based on the
+Landau-Lifshitz-Gilbert equation.",1502.02699v1
+2015-07-24,Boosting Domain Wall Propagation by Notches,"We report a counter-intuitive finding that notches in an otherwise
+homogeneous magnetic nanowire can boost current-induced domain wall (DW)
+propagation. DW motion in notch-modulated wires can be classified into three
+phases: 1) A DW is pinned around a notch when the current density is below the
+depinning current density. 2) DW propagation velocity is boosted by notches
+above the depinning current density and when non-adiabatic spin-transfer torque
+strength $\beta$ is smaller than the Gilbert damping constant $\alpha$. The
+boost can be manyfold. 3) DW propagation velocity is hindered when $\beta >
+\alpha$. The results are explained by using the Thiele equation.",1507.06748v1
+2016-01-23,Nonlinear magnetization dynamics of antiferromagnetic spin resonance induced by intense terahertz magnetic field,"We report on the nonlinear magnetization dynamics of a HoFeO3 crystal induced
+by a strong terahertz magnetic field resonantly enhanced with a split ring
+resonator and measured with magneto-optical Kerr effect microscopy. The
+terahertz magnetic field induces a large change (~40%) in the spontaneous
+magnetization. The frequency of the antiferromagnetic resonance decreases in
+proportion to the square of the magnetization change. A modified
+Landau-Lifshitz-Gilbert equation with a phenomenological nonlinear damping term
+quantitatively reproduced the nonlinear dynamics.",1601.06213v1
+2017-08-11,Gradient expansion formalism for generic spin torques,"We propose a new quantum-mechanical formalism to calculate spin torques based
+on the gradient expansion, which naturally involves spacetime gradients of the
+magnetization and electromagnetic fields. We have no assumption in the
+small-amplitude formalism or no difficulty in the SU($2$) gauge transformation
+formalism. As a representative, we calculate the spin renormalization, Gilbert
+damping, spin-transfer torque, and $\beta$-term in a three-dimensional
+ferromagnetic metal with nonmagnetic and magnetic impurities being taken into
+account within the self-consistent Born approximation. Our results serve as a
+first-principles formalism for spin torques.",1708.03424v1
+2019-06-03,Magnon-phonon interactions in magnetic insulators,"We address the theory of magnon-phonon interactions and compute the
+corresponding quasi-particle and transport lifetimes in magnetic insulators
+with focus on yttrium iron garnet at intermediate temperatures from anisotropy-
+and exchange-mediated magnon-phonon interactions, the latter being derived from
+the volume dependence of the Curie temperature. We find in general weak effects
+of phonon scattering on magnon transport and the Gilbert damping of the
+macrospin Kittel mode. The magnon transport lifetime differs from the
+quasi-particle lifetime at shorter wavelengths.",1906.01042v1
+2019-09-17,Microwave induced tunable subharmonic steps in superconductor-ferromagnet-superconductor Josephson junction,"We investigate the coupling between ferromagnet and superconducting phase
+dynamics in superconductor-ferromagnet-superconductor Josephson junction. The
+current-voltage characteristics of the junction demonstrate a pattern of
+subharmonic current steps which forms a devil's staircase structure. We show
+that a width of the steps becomes maximal at ferromagnetic resonance. Moreover,
+we demonstrate that the structure of the steps and their widths can be tuned by
+changing the frequency of the external magnetic field, ratio of Josephson to
+magnetic energy, Gilbert damping and the junction size.",1909.08004v1
+2019-09-19,Magnetization dynamics of the compensated ferrimagnet $Mn_{2}Ru_{x}Ga$,"Here we study both static and time-resolved dynamic magnetic properties of
+the compensated ferrimagnet from room temperature down to 10K, thus crossing
+the magnetic compensation temperature $T_{M}$. The behaviour is analysed with a
+model of a simple collinear ferrimagnet with uniaxial anisotropy and
+site-specific gyromagnetic ratios. We find a maximum zero-applied-field
+resonance frequency of $\sim$160GHz and a low intrinsic Gilbert damping
+$\alpha$$\sim$0.02, making it a very attractive candidate for various
+spintronic applications.",1909.09085v1
+2019-11-28,Transport properties of spin superfluids: comparing easy-plane ferro- and antiferromagnets,"We present a study on spin-superfluid transport based on an atomistic,
+classical spin model. Easy-plane ferro- as well as antiferromagnets are
+considered, which allows for a direct comparison of these two material classes
+based on the same model assumptions. We find a spin-superfluid transport which
+is robust against variations of the boundary conditions, thermal fluctuations,
+and dissipation modeled via Gilbert damping. Though the spin accumulations is
+smaller for antiferromagnets the range of the spin-superfluid transport turns
+out to be identical for ferro- and antiferromagnets. Finally, we calculate and
+explore the role of the driving frequency and especially the critical
+frequency, where phase slips occur and the spin accumulation breaks down.",1911.12786v1
+2020-01-17,Fermi Level Controlled Ultrafast Demagnetization Mechanism in Half-Metallic Heusler Alloy,"The electronic band structure-controlled ultrafast demagnetization mechanism
+in Co2FexMn1-xSi Heusler alloy is underpinned by systematic variation of
+composition. We find the spin-flip scattering rate controlled by spin density
+of states at Fermi level is responsible for non-monotonic variation of
+ultrafast demagnetization time ({\tau}M) with x with a maximum at x = 0.4.
+Furthermore, Gilbert damping constant exhibits an inverse relationship with
+{\tau}M due to the dominance of inter-band scattering mechanism. This
+establishes a unified mechanism of ultrafast spin dynamics based on Fermi level
+position.",2001.06217v1
+2020-04-17,Collective coordinate study of spin wave emission from dynamic domain wall,"We study theoretically the spin wave emission from a moving domain wall in a
+ferromagnet. Introducing a deformation mode describing a modulation of the wall
+thickness in the collective coordinate description, we show that thickness
+variation couples to the spin wave linearly and induces spin wave emission. The
+dominant emitted spin wave turns out to be polarized in the out-of wall plane
+($\phi$)-direction. The emission contributes to the Gilbert damping parameter
+proportional to $\hbar\omega_\phi/K$, the ratio of the angular frequency
+$\omega_\phi$ of $\phi$ and the easy-axis anisotropy energy $K$.",2004.08082v1
+2021-03-10,Anisotropic superconducting spin transport at magnetic interfaces,"We present a theoretical investigation of anisotropic superconducting spin
+transport at a magnetic interface between a p-wave superconductor and a
+ferromagnetic insulator. Our formulation describes the ferromagnetic resonance
+modulations due to spin current generation depending on spin-triplet Cooper
+pair, including the frequency shift and enhanced Gilbert damping, in a unified
+manner. We find that the Cooper pair symmetry is detectable from the
+qualitative behavior of the ferromagnetic resonance modulation. Our theory
+paves the way toward anisotropic superconducting spintronics.",2103.05871v3
+2022-01-16,Ferromagnetic resonance modulation in $d$-wave superconductor/ferromagnetic insulator bilayer systems,"We investigate ferromagnetic resonance (FMR) modulation in $d$-wave
+superconductor (SC)/ferromagnetic insulator (FI) bilayer systems theoretically.
+The modulation of the Gilbert damping in these systems reflects the existence
+of nodes in the $d$-wave SC and shows power-law decay characteristics within
+the low-temperature and low-frequency limit. Our results indicate the
+effectiveness of use of spin pumping as a probe technique to determine the
+symmetry of unconventional SCs with high sensitivity for nanoscale thin films.",2201.06060v2
+2022-09-28,Unidirectional magnetic coupling,"We show that interlayer Dzyaloshinskii-Moriya interaction in combination with
+non-local Gilbert damping gives rise to unidirectional magnetic coupling. That
+is, the coupling between two magnetic layers -- say the left and right layer --
+is such that dynamics of the left layer leads to dynamics of the right layer,
+but not vice versa. We discuss the implications of this result for the magnetic
+susceptibility of a magnetic bilayer, electrically-actuated spin-current
+transmission, and unidirectional spin-wave packet generation and propagation.
+Our results may enable a route towards spin-current and spin-wave diodes and
+further pave the way to design spintronic devices via reservoir engineering.",2209.14179v1
+2023-08-11,Dynamical Majorana Ising spin response in a topological superconductor-magnet hybrid by microwave irradiation,"We study a dynamical spin response of surface Majorana modes in a topological
+superconductor-magnet hybrid under microwave irradiation. We find a method to
+toggle between dissipative and non-dissipative Majorana Ising spin dynamics by
+adjusting the external magnetic field angle and the microwave frequency. This
+reflects the topological nature of the Majorana modes, enhancing the Gilbert
+damping of the magnet, thereby, providing a detection method for the Majorana
+Ising spins. Our findings illuminate a magnetic probe for Majorana modes,
+paving the path to innovative spin devices.",2308.05955v2
+2012-10-25,Decay rates for the damped wave equation on the torus,"We address the decay rates of the energy for the damped wave equation when
+the damping coefficient $b$ does not satisfy the Geometric Control Condition
+(GCC). First, we give a link with the controllability of the associated
+Schr\""odinger equation. We prove in an abstract setting that the observability
+of the Schr\""odinger group implies that the semigroup associated to the damped
+wave equation decays at rate $1/\sqrt{t}$ (which is a stronger rate than the
+general logarithmic one predicted by the Lebeau Theorem).
+  Second, we focus on the 2-dimensional torus. We prove that the best decay one
+can expect is $1/t$, as soon as the damping region does not satisfy GCC.
+Conversely, for smooth damping coefficients $b$, we show that the semigroup
+decays at rate $1/t^{1-\eps}$, for all $\eps >0$. The proof relies on a second
+microlocalization around trapped directions, and resolvent estimates.
+  In the case where the damping coefficient is a characteristic function of a
+strip (hence discontinuous), St\'{e}phane Nonnenmacher computes in an appendix
+part of the spectrum of the associated damped wave operator, proving that the
+semigroup cannot decay faster than $1/t^{2/3}$. In particular, our study shows
+that the decay rate highly depends on the way $b$ vanishes.",1210.6879v1
+2006-10-04,On the dynamics of spin systems in the Landau-Lifshitz theory,"In the framework of the Landau-Lifshitz equations without any dissipation (an
+approximation which may also be helpful for finite but weak Gilbert damping),
+with all interactions included, for general ground states, geometries and
+domain structures, and many types of effective fields the dynamics of the spin
+precession around this ground state is considered.
+  At first the precession is treated in the linear approximation. For the
+eigenmodes of the precession one has a `rule of geometric mean' for the
+eigenfrequencies. For the eigenmodes pseudo-orthogonality relations are
+obtained, which reflect the gyrotropic and elliptic character of the spin
+precession and differ from those known from the Schrodinger equation. Moreover,
+pseudo-orthogonality relations are valid 'everywhere' (e.g., both in the outer
+region and in the core region of a magnetic vortex).
+  Then also some aspects of the nonlinear mode coupling with emphasis on
+`confluence' and `splitting' processes of elementary magnetic spin-wave
+excitations are considered. At the same time these processes contribute to the
+Gilbert damping.
+  There are thus essential differences to quantum mechanics, although at a
+first glance one discovers many similarities. From the results one may also get
+insights of why these systems are so complex that (although the essential
+quantities depend only on the local values of the partially long-ranged
+effective magnetic fields) practically only detailed experiments and computer
+simulations make sense.",0610122v4
+2016-04-26,First principles studies of the Gilbert damping and exchange interactions for half-metallic Heuslers alloys,"Heusler alloys have been intensively studied due to the wide variety of
+properties that they exhibit. One of these properties is of particular interest
+for technological applications, i.e. the fact that some Heusler alloys are
+half-metallic. In the following, a systematic study of the magnetic properties
+of three different Heusler families $\textrm{Co}_2\textrm{Mn}\textrm{Z}$,
+$\text{Co}_2\text{Fe}\text{Z}$ and $\textrm{Mn}_2\textrm{V}\textrm{Z}$ with
+$\text{Z}=\left(\text{Al, Si, Ga, Ge}\right)$ is performed. A key aspect is the
+determination of the Gilbert damping from first principles calculations, with
+special focus on the role played by different approximations, the effect that
+substitutional disorder and temperature effects. Heisenberg exchange
+interactions and critical temperature for the alloys are also calculated as
+well as magnon dispersion relations for representative systems, the
+ferromagnetic $\textrm{Co}_2\textrm{Fe}\textrm{Si}$ and the ferrimagnetic
+$\textrm{Mn}_2\textrm{V}\textrm{Al}$. Correlations effects beyond standard
+density-functional theory are treated using both the local spin density
+approximation including the Hubbard $U$ and the local spin density
+approximation plus dynamical mean field theory approximation, which allows to
+determine if dynamical self-energy corrections can remedy some of the
+inconsistencies which were previously reported for these alloys.",1604.07552v1
+2016-12-21,"Spin Pumping, Dissipation, and Direct and Alternating Inverse Spin Hall Effects in Magnetic Insulator-Normal Metal Bilayers","We theoretically consider the spin-wave mode- and wavelength-dependent
+enhancement of the Gilbert damping in magnetic insulator--normal metal bilayers
+due to spin pumping as well as the enhancement's relation to direct and
+alternating inverse spin Hall voltages in the normal metal. In the
+long-wavelength limit, including long-range dipole interactions, the ratio of
+the enhancement for transverse volume modes to that of the macrospin mode is
+equal to two. With an out-of-plane magnetization, this ratio decreases with
+both an increasing surface anisotropic energy and mode number. If the surface
+anisotropy induces a surface state, the enhancement can be an order of
+magnitude larger than for to the macrospin. With an in-plane magnetization, the
+induced dissipation enhancement can be understood by mapping the anisotropy
+parameter to the out-of-plane case with anisotropy. For shorter wavelengths, we
+compute the enhancement numerically and find good agreement with the analytical
+results in the applicable limits. We also compute the induced direct- and
+alternating-current inverse spin Hall voltages and relate these to the magnetic
+energy stored in the ferromagnet. Because the magnitude of the direct spin Hall
+voltage is a measure of spin dissipation, it is directly proportional to the
+enhancement of Gilbert damping. The alternating spin Hall voltage exhibits a
+similar in-plane wave-number dependence, and we demonstrate that it is greatest
+for surface-localized modes.",1612.07020v2
+2019-10-29,Perpendicular magnetic anisotropy in Pt/Co-based full Heusler alloy/MgO thin films structures,"Perpendicular magnetic anisotropy (PMA) in ultrathin magnetic structures is a
+key ingredient for the development of electrically controlled spintronic
+devices. Due to their relatively large spin-polarization, high Curie
+temperature and low Gilbert damping the Co-based full Heusler alloys are of
+special importance from a scientific and applications point of view. Here, we
+study the mechanisms responsible for the PMA in Pt/Co-based full Heusler
+alloy/MgO thin films structures. We show that the ultrathin Heusler films
+exhibit strong PMA even in the absence of magnetic annealing. By means of
+ferromagnetic resonance experiments, we demonstrate that the effective
+magnetization shows a two-regime behavior depending on the thickness of the
+Heusler layers. Using Auger spectroscopy measurements, we evidence
+interdiffusion at the underlayer/Heusler interface and the formation of an
+interfacial CoFe-rich layer which causes the two-regime behavior. In the case
+of the ultrathin films, the interfacial CoFe-rich layer promotes the strong PMA
+through the electronic hybridization of the metal alloy and oxygen orbitals
+across the ferromagnet/MgO interface. In addition, the interfacial CoFe-rich
+layer it is also generating an increase of the Gilbert damping for the
+ultrathin films beyond the spin-pumping effect. Our results illustrate that the
+strong PMA is not an intrinsic property of the Heusler/MgO interface but it is
+actively influenced by the interdiffusion, which can be tuned by a proper
+choice of the underlayer material, as we show for the case of the Pt, Ta and Cr
+underlayers.",1910.13107v1
+2020-10-15,Spin injection characteristics of Py/graphene/Pt by gigahertz and terahertz magnetization dynamics driven by femtosecond laser pulse,"Spin transport characteristics of graphene has been extensively studied so
+far. The spin transport along c-axis is however reported by rather limited
+number of papers. We have studied spin transport characteristics through
+graphene along c-axis with permalloy(Py)/graphene(Gr)/Pt by gigahertz (GHz) and
+terahertz (THz) magnetization dynamics driven by femtosecond laser pulses. The
+relatively simple sample structure does not require electrodes on the sample.
+The graphene layer was prepared by chemical vapor deposition and transferred on
+Pt film. The quality of graphene layer was characterized by Raman microscopy.
+Time resolved magneto-optical Kerr effect is used to characterize gigahertz
+magnetization dynamics. Magnetization precession is clearly observed both for
+Pt/Py and Pt/Gr/Py. The Gilbert damping constant of Pt/Py was 0.015, indicates
+spin pumping effect from Py to Pt. The Gilbert damping constant of Pt/Gr/Py is
+found to be 0.011, indicates spin injection is blocked by graphene layer. We
+have also performed the measurement of THz emission for Pt/Py and Pt/Gr/Py.
+While the THz emission is clearly observed for Pt/Py, a strong reduction of THz
+emission is observed for Pt/Gr/Py. With these two different experiments, and
+highly anisotropic resistivity of graphite, we conclude that the vertical spin
+transport is strongly suppressed by the graphene layer.",2010.07694v1
+2021-03-17,Spin injection efficiency at metallic interfaces probed by THz emission spectroscopy,"Terahertz (THz) spin-to-charge conversion has become an increasingly
+important process for THz pulse generation and as a tool to probe ultrafast
+spin interactions at magnetic interfaces. However, its relation to traditional,
+steady state, ferromagnetic resonance techniques is poorly understood. Here we
+investigate nanometric trilayers of Co/X/Pt (X=Ti, Au or Au0:85W0:15) as a
+function of the 'X' layer thickness, where THz emission generated by the
+inverse spin Hall effect is compared to the Gilbert damping of the
+ferromagnetic resonance. Through the insertion of the 'X' layer we show that
+the ultrafast spin current injected in the non-magnetic layer defines a direct
+spin conductance, whereas the Gilbert damping leads to an effective spin
+mixing-conductance of the trilayer. Importantly, we show that these two
+parameters are connected to each other and that spin-memory losses can be
+modeled via an effective Hamiltonian with Rashba fields. This work highlights
+that magneto-circuits concepts can be successfully extended to ultrafast
+spintronic devices, as well as enhancing the understanding of spin-to-charge
+conversion processes through the complementarity between ultrafast THz
+spectroscopy and steady state techniques.",2103.09557v1
+2021-09-13,Control of magnetization dynamics by substrate orientation in YIG thin films,"Yttrium Iron Garnet (YIG) and bismuth (Bi) substituted YIG (Bi0.1Y2.9Fe5O12,
+BYG) films are grown in-situ on single crystalline Gadolinium Gallium Garnet
+(GGG) substrates [with (100) and (111) orientations] using pulsed laser
+deposition (PLD) technique. As the orientation of the Bi-YIG film changes from
+(100) to (111), the lattice constant is enhanced from 12.384 {\AA} to 12.401
+{\AA} due to orientation dependent distribution of Bi3+ ions at dodecahedral
+sites in the lattice cell. Atomic force microscopy (AFM) images show smooth
+film surfaces with roughness 0.308 nm in Bi-YIG (111). The change in substrate
+orientation leads to the modification of Gilbert damping which, in turn, gives
+rise to the enhancement of ferromagnetic resonance (FMR) line width. The best
+values of Gilbert damping are found to be (0.54)*10-4, for YIG (100) and
+(6.27)*10-4, for Bi-YIG (111) oriented films. Angle variation measurements of
+the Hr are also performed, that shows a four-fold symmetry for the resonance
+field in the (100) grown film. In addition, the value of effective
+magnetization (4{\pi}Meff) and extrinsic linewidth ({\Delta}H0) are observed to
+be dependent on substrate orientation. Hence PLD growth can assist
+single-crystalline YIG and BYG films with a perfect interface that can be used
+for spintronics and related device applications.",2109.05901v1
+2022-06-06,Probing spin dynamics of ultra-thin van der Waals magnets via photon-magnon coupling,"Layered van der Waals (vdW) magnets can maintain a magnetic order even down
+to the single-layer regime and hold promise for integrated spintronic devices.
+While the magnetic ground state of vdW magnets was extensively studied, key
+parameters of spin dynamics, like the Gilbert damping, crucial for designing
+ultra-fast spintronic devices, remains largely unexplored. Despite recent
+studies by optical excitation and detection, achieving spin wave control with
+microwaves is highly desirable, as modern integrated information technologies
+predominantly are operated with these. The intrinsically small numbers of
+spins, however, poses a major challenge to this.
+  Here, we present a hybrid approach to detect spin dynamics mediated by
+photon-magnon coupling between high-Q superconducting resonators and ultra-thin
+flakes of Cr$_2$Ge$_2$Te$_6$ (CGT) as thin as 11\,nm. We test and benchmark our
+technique with 23 individual CGT flakes and extract an upper limit for the
+Gilbert damping parameter. These results are crucial in designing on-chip
+integrated circuits using vdW magnets and offer prospects for probing spin
+dynamics of monolayer vdW magnets.",2206.02460v2
+2022-09-01,Growth parameters of Bi0.1Y2.9Fe5O12 thin films for high frequency applications,"The growth and characterization of Bismuth (Bi) substituted YIG (Bi-YIG,
+Bi0.1Y2.9Fe5O12) thin films are reported. Pulsed laser deposited (PLD) films
+with thicknesses ranging from 20 to 150 nm were grown on Gadolinium Gallium
+Garnet substrates. Two substrate orientations of (100) and (111) were
+considered. The enhanced distribution of Bi3+ ions at dodecahedral site along
+(111) is observed to lead to an increment in lattice constant from 12.379
+angstrom in (100) to 12.415 angstrom in (111) oriented films. Atomic force
+microscopy images showed decreasing roughness with increasing film thickness.
+Compared to (100) grown films, (111) oriented films showed an increase in
+ferromagnetic resonance linewidth and consequent increase in Gilbert damping.
+The lowest Gilbert damping values are found to be (1.06) * 10E-4 for (100) and
+(2.30) * 10E-4 for (111) oriented films with thickness of 150 nm. The observed
+values of extrinsic linewidth, effective magnetization, and anisotropic field
+are related to thickness of the films and substrate orientation. In addition,
+the in-plane angular variation established four-fold symmetry for the (100)
+deposited films unlike the case of (111) deposited films. This study prescribes
+growth conditions for PLD grown single-crystalline Bi-YIG films towards desired
+high frequency and magneto-optical device applications.",2209.00558v1
+2019-10-17,Modified different nonlinearities for weakly coupled systems of semilinear effectively damped waves with different time-dependent coefficients in the dissipation terms,"We prove the global existence of small data solution in all space dimension
+for weakly coupled systems of semi-linear effectively damped wave, with
+different time-dependent coefficients in the dissipation terms. Moreover,
+nonlinearity terms $ f(t,u) $ and $ g(t,v) $ satisfying some properties of the
+parabolic equation. We study the problem in several classes of regularity.",1910.07731v1
+2021-10-10,Global existence of solutions for semilinear damped wave equations with variable coefficients,"We consider the Cauchy problem for the damped wave equations with variable
+coefficients a(x) having power type nonlinearity |u|^p. We discuss the global
+existence of solutions for small initial data and investigate the relation
+between the range of a(x) and the order p.",2110.04718v2
+2023-04-23,Decay rates for a variable-coefficient wave equation with nonlinear time-dependent damping,"In this paper, a class of variable-coefficient wave equations equipped with
+time-dependent damping and the nonlinear source is considered. We show that the
+total energy of the system decays to zero with an explicit and precise decay
+rate estimate under different assumptions on the feedback with the help of the
+method of weighted energy integral.",2304.11522v1
+2019-07-10,Determination of the damping co-efficient of electrons in optically transparent glasses at the true resonance frequency in the ultraviolet from an analysis of the Lorentz-Maxwell model of dispersion,"The Lorentz-Maxwell model of dispersion of light has been analyzed in this
+paper to determine the true resonance frequency in the ultraviolet for the
+electrons in optically transparent glasses and the damping coefficient at this
+frequency. For this we needed the refractive indices of glass in the optical
+frequency range. We argue that the true resonance condition in the absorption
+region prevails when the frequency at which the absorption coefficient is
+maximum is the same as the frequency at which the average energy per cycle of
+the electrons is also a maximum. We have simultaneously solved the two
+equations obtained from the two maxima conditions numerically to arrive at a
+unique solution for the true resonance frequency and the damping coefficient at
+this frequency. Assuming the damping coefficient to be constant over a small
+frequency range in the absorption region, we have determined the frequencies at
+which the extinction coefficient and the reflectance are maxima. These
+frequencies match very well with the published data for silica glasses
+available from the literature.",1907.04499v1
+2012-07-17,Asymptotic Dynamics of a Class of Coupled Oscillators Driven by White Noises,"This paper is devoted to the study of the asymptotic dynamics of a class of
+coupled second order oscillators driven by white noises. It is shown that any
+system of such coupled oscillators with positive damping and coupling
+coefficients possesses a global random attractor. Moreover, when the damping
+and the coupling coefficients are sufficiently large, the global random
+attractor is a one-dimensional random horizontal curve regardless of the
+strength of the noises, and the system has a rotation number, which implies
+that the oscillators in the system tend to oscillate with the same frequency
+eventually and therefore the so called frequency locking is successful. The
+results obtained in this paper generalize many existing results on the
+asymptotic dynamics for a single second order noisy oscillator to systems of
+coupled second order noisy oscillators. They show that coupled damped second
+order oscillators with large damping have similar asymptotic dynamics as the
+limiting coupled first order oscillators as the damping goes to infinite and
+also that coupled damped second order oscillators have similar asymptotic
+dynamics as their proper space continuous counterparts, which are of great
+practical importance.",1207.3864v1
+2020-09-22,Sharp exponential decay rates for anisotropically damped waves,"In this article, we study energy decay of the damped wave equation on compact
+Riemannian manifolds where the damping coefficient is anisotropic and modeled
+by a pseudodifferential operator of order zero. We prove that the energy of
+solutions decays at an exponential rate if and only if the damping coefficient
+satisfies an anisotropic analogue of the classical geometric control condition,
+along with a unique continuation hypothesis. Furthermore, we compute an
+explicit formula for the optimal decay rate in terms of the spectral abscissa
+and the long-time averages of the principal symbol of the damping over
+geodesics, in analogy to the work of Lebeau for the isotropic case. We also
+construct genuinely anisotropic dampings which satisfy our hypotheses on the
+flat torus.",2009.10832v2
+2017-02-27,Current Induced Damping of Nanosized Quantum Moments in the Presence of Spin-Orbit Interaction,"Motivated by the need to understand current-induced magnetization dynamics at
+the nanoscale, we have developed a formalism, within the framework of Keldysh
+Green function approach, to study the current-induced dynamics of a
+ferromagnetic (FM) nanoisland overlayer on a spin-orbit-coupling (SOC) Rashba
+plane. In contrast to the commonly employed classical micromagnetic LLG
+simulations the magnetic moments of the FM are treated {\it quantum
+mechanically}. We obtain the density matrix of the whole system consisting of
+conduction electrons entangled with the local magnetic moments and calculate
+the effective damping rate of the FM. We investigate two opposite limiting
+regimes of FM dynamics: (1) The precessional regime where the magnetic
+anisotropy energy (MAE) and precessional frequency are smaller than the
+exchange interactions, and (2) The local spin-flip regime where the MAE and
+precessional frequency are comparable to the exchange interactions. In the
+former case, we show that due to the finite size of the FM domain, the
+\textquotedblleft Gilbert damping\textquotedblright does not diverge in the
+ballistic electron transport regime, in sharp contrast to Kambersky's breathing
+Fermi surface theory for damping in metallic FMs. In the latter case, we show
+that above a critical bias the excited conduction electrons can switch the
+local spin moments resulting in demagnetization and reversal of the
+magnetization. Furthermore, our calculations show that the bias-induced
+antidamping efficiency in the local spin-flip regime is much higher than that
+in the rotational excitation regime.",1702.08408v2
+2021-06-16,Spin-Torque-driven Terahertz Auto Oscillations in Non-Collinear Coplanar Antiferromagnets,"We theoretically and numerically study the terahertz auto oscillations in
+thin-film metallic non-collinear coplanar antiferromagnets (AFMs), such as
+$\mathrm{Mn_{3}Sn}$ and $\mathrm{Mn_{3}Ir}$, under the effect of anti-damping
+spin-torque with spin polarization perpendicular to the plane of the film. To
+obtain the order parameter dynamics in these AFMs, we solve three
+Landau-Lifshitz-Gilbert equations coupled by exchange interactions assuming
+both single- and multi-domain (micromagnetics) dynamical processes. In the
+limit of strong exchange interaction, the oscillatory dynamics of the order
+parameter in these AFMs, which have opposite chiralities, could be mapped to
+that of a linear damped-driven pendulum in the case of $\mathrm{Mn_{3}Sn}$, and
+a non-linear damped-driven pendulum in case of $\mathrm{Mn_{3}Ir}$. The
+theoretical framework allows us to identify the input current requirements as a
+function of the material and geometry parameters for exciting an oscillatory
+response. We also obtain a closed-form approximate solution of the oscillation
+frequency for large input currents in case of both $\mathrm{Mn_{3}Ir}$ and
+$\mathrm{Mn_{3}Sn}$. Our analytical predictions of threshold current and
+oscillation frequency agree well with the numerical results and thus can be
+used as compact models to design and optimize the auto oscillator. Employing a
+circuit model, based on the principle of tunnel anisotropy magnetoresistance,
+we present detailed models of the output power and efficiency versus
+oscillation frequency of the auto oscillator. Finally, we explore the spiking
+dynamics of two unidirectional as well as bidirectional coupled AFM oscillators
+using non-linear damped-driven pendulum equations.",2106.08528v2
+2023-01-30,Investigation of Ultrafast Demagnetization and Gilbert Damping and their Correlation in Different Ferromagnetic Thin Films Grown Under Identical Conditions,"Following the demonstration of laser-induced ultrafast demagnetization in
+ferromagnetic nickel, several theoretical and phenomenological propositions
+have sought to uncover its underlying physics. In this work we revisit the
+three temperature model (3TM) and the microscopic three temperature model
+(M3TM) to perform a comparative analysis of ultrafast demagnetization in
+20-nm-thick cobalt, nickel and permalloy thin films measured using an
+all-optical pump-probe technique. In addition to the ultrafast dynamics at the
+femtosecond timescales, the nanosecond magnetization precession and damping are
+recorded at various pump excitation fluences revealing a fluence-dependent
+enhancement in both the demagnetization times and the damping factors. We
+confirm that the Curie temperature to magnetic moment ratio of a given system
+acts as a figure of merit for the demagnetization time, while the
+demagnetization times and damping factors show an apparent sensitivity to the
+density of states at the Fermi level for a given system. Further, from
+numerical simulations of the ultrafast demagnetization based on both the 3TM
+and the M3TM, we extract the reservoir coupling parameters that best reproduce
+the experimental data and estimate the value of the spin flip scattering
+probability for each system. We discuss how the fluence-dependence of
+inter-reservoir coupling parameters so extracted may reflect a role played by
+nonthermal electrons in the magnetization dynamics at low laser fluences.",2301.12797v1
+2016-10-01,The destabilizing effect of external damping: Singular flutter boundary for the Pfluger column with vanishing external dissipation,"Elastic structures loaded by nonconservative positional forces are prone to
+instabilities induced by dissipation: it is well-known in fact that internal
+viscous damping destabilizes the marginally stable Ziegler's pendulum and
+Pfluger column (of which the Beck's column is a special case), two structures
+loaded by a tangential follower force. The result is the so-called
+'destabilization paradox', where the critical force for flutter instability
+decreases by an order of magnitude when the coefficient of internal damping
+becomes infinitesimally small. Until now external damping, such as that related
+to air drag, is believed to provide only a stabilizing effect, as one would
+intuitively expect. Contrary to this belief, it will be shown that the effect
+of external damping is qualitatively the same as the effect of internal
+damping, yielding a pronounced destabilization paradox. Previous results
+relative to destabilization by external damping of the Ziegler's and Pfluger's
+elastic structures are corrected in a definitive way leading to a new
+understanding of the destabilizating role played by viscous terms.",1611.03886v1
+2018-05-16,Stabilization rates for the damped wave equation with Hölder-regular damping,"We study the decay rate of the energy of solutions to the damped wave
+equation in a setup where the geometric control condition is violated. We
+consider damping coefficients which are $0$ on a strip and vanish like
+polynomials, $x^{\beta}$. We prove that the semigroup cannot be stable at rate
+faster than $1/t^{(\beta+2)/(\beta+3)}$ by producing quasimodes of the
+associated stationary damped wave equation. We also prove that the semigroup is
+stable at rate at least as fast as $1/t^{(\beta+2)/(\beta+4)}$. These two
+results establish an explicit relation between the rate of vanishing of the
+damping and rate of decay of solutions. Our result partially generalizes a
+decay result of Nonnemacher in which the damping is an indicator function on a
+strip.",1805.06535v3
+2014-02-07,One-dimensional random attractor and rotation number of the stochastic damped sine-Gordon equation,"This paper is devoted to the study of the asymptotic dynamics of the
+stochastic damped sine-Gordon equation with homogeneous Neumann boundary
+condition. It is shown that for any positive damping and diffusion
+coefficients, the equation possesses a random attractor, and when the damping
+and diffusion coefficients are sufficiently large, the random attractor is a
+one-dimensional random horizontal curve regardless of the strength of noise.
+Hence its dynamics is not chaotic. It is also shown that the equation has a
+rotation number provided that the damping and diffusion coefficients are
+sufficiently large, which implies that the solutions tend to oscillate with the
+same frequency eventually and the so called frequency locking is successful.",1402.1787v1
+2021-02-01,Blow-up and lifespan estimates for a damped wave equation in the Einstein-de Sitter spacetime with nonlinearity of derivative type,"In this article, we investigate the blow-up for local solutions to a
+semilinear wave equation in the generalized Einstein - de Sitter spacetime with
+nonlinearity of derivative type. More precisely, we consider a semilinear
+damped wave equation with a time-dependent and not summable speed of
+propagation and with a time-dependent coefficient for the linear damping term
+with critical decay rate. We prove in this work that the results obtained in a
+previous work, where the damping coefficient takes two particular values $0$ or
+$2$, can be extended for any positive damping coefficient. In the blow-up case,
+the upper bound of the exponent of the nonlinear term is given, and the
+lifespan estimate of the global existence time is derived as well.",2102.01137v2
+2023-10-24,Frictional weakening of a granular sheared layer due to viscous rolling revealed by Discrete Element Modeling,"Considering a 3D sheared granular layer modeled with discrete elements, it is
+well known the rolling resistance significantly influences the mechanical
+behavior. Even if the rolling resistance role has been deeply investigated as
+it is commonly used to represent the the roughness of the grains and the
+interparticle locking, the role of rolling viscous damping coefficient has been
+largely overlooked so far. This parameter is rarely used or only to dissipate
+the energy and to converge numerically. This paper revisits the physical role
+of those coefficients with a parametric study of the rolling friction and the
+rolling damping for a sheared layer at different shear speeds and different
+confinement pressures. It has been observed that the damping coefficient
+induces a frictional weakening. Hence, competition between the rolling
+resistance and the rolling damping occurs. Angular resistance aims to avoid
+grains rolling, decreasing the difference between the angular velocities of
+grains. Whereas, angular damping acts in the opposite, avoiding a change in the
+difference between the angular velocities of grains. In consequence, grains
+keep rolling and the sample strength decreases. This effect must be considered
+to not overestimate the frictional response of a granular layer.",2310.15945v1
+2019-04-24,On the Energy Decay Rate of the Fractional Wave Equation on $\mathbb{R}$ with Relatively Dense Damping,"We establish upper bounds for the decay rate of the energy of the damped
+fractional wave equation when the averages of the damping coefficient on all
+intervals of a fixed length are bounded below. If the power of the fractional
+Laplacian, $s$, is between 0 and 2, the decay is polynomial. For $s \ge 2$, the
+decay is exponential. Second, we show that our assumption on the damping is
+necessary for the energy to decay exponentially.",1904.10946v3
+2021-02-28,Stability for an inverse source problem of the damped biharmonic plate equation,"This paper is concerned with the stability of the inverse source problem for
+the damped biharmonic plate equation in three dimensions. The stability
+estimate consists of the Lipschitz type data discrepancy and the high frequency
+tail of the source function, where the latter decreases as the upper bound of
+the frequency increases. The stability also shows exponential dependence on the
+constant damping coefficient. The analysis employs Carleman estimates and time
+decay estimates for the damped plate wave equation to obtain an exact
+observability bound and depends on the study of the resonance-free region and
+an upper bound of the resolvent of the biharmonic operator with respect to the
+complex wavenumber.",2103.00461v1
+2023-02-13,Damping of gravitational waves in f(R) gravity,"We study the damping of $f(R)$ gravitational waves by matter in flat
+spacetime and in expanding universe. In the former case, we find that the
+Landau damping of scalar mode in $f(R)$ theory exists, while that of the tensor
+mode in general relativity does not; we also present the viscosity coefficients
+and dispersion relations of the two modes. In the later case, we investigate
+the evolution of tensor and scalar modes in Friedmann-Robertson-Walker (FRW)
+cosmology with a matter distribution; by considering the case of $f(R)=R+\al
+R^2$, we analysis the influence of parameter $\al$ on wave damping,and put
+restrictions on its magnitude.",2302.06402v2
+2023-03-20,Nonlinear Damping and Field-aligned Flows of Propagating Shear Alfvén Waves with Braginskii Viscosity,"Braginskii MHD provides a more accurate description of many plasma
+environments than classical MHD since it actively treats the stress tensor
+using a closure derived from physical principles. Stress tensor effects
+nonetheless remain relatively unexplored for solar MHD phenomena, especially in
+nonlinear regimes. This paper analytically examines nonlinear damping and
+longitudinal flows of propagating shear Alfv\'en waves. Most previous studies
+of MHD waves in Braginskii MHD considered the strict linear limit of vanishing
+wave perturbations. We show that those former linear results only apply to
+Alfv\'en wave amplitudes in the corona that are so small as to be of little
+interest, typically a wave energy less than $10^{-11}$ times the energy of the
+background magnetic field. For observed wave amplitudes, the Braginskii viscous
+dissipation of coronal Alfv\'en waves is nonlinear and a factor around $10^9$
+stronger than predicted by the linear theory. Furthermore, the dominant damping
+occurs through the parallel viscosity coefficient $\eta_0$, rather than the
+perpendicular viscosity coefficient $\eta_2$ in the linearized solution. This
+paper develops the nonlinear theory, showing that the wave energy density
+decays with an envelope $(1+z/L_d)^{-1}$. The damping length $L_d$ exhibits an
+optimal damping solution, beyond which greater viscosity leads to lower
+dissipation as the viscous forces self-organise the longitudinal flow to
+suppress damping. Although the nonlinear damping greatly exceeds the linear
+damping, it remains negligible for many coronal applications.",2303.11128v1
+2024-01-09,Damping Separation of Finite Open Systems in Gravity-Related Experiments in the Free Molecular Flow Regime,"The residual gas damping of the test mass (TM) in the free molecular flow
+regime is studied in the finite open systems for high-precision gravity-related
+experiments. Through strict derivation, we separate the damping coefficients
+for two finite open systems, i.e., the bi-plate system and the sensor core
+system, into base damping and diffusion damping. This elucidates the
+relationship between the free damping in the infinite gas volume and the
+proximity damping in the constrained volume, unifies them into one microscopic
+picture, and allows us to point out three pathways of energy dissipation in the
+bi-plate gap. We also provide the conditions that need to be met to achieve
+this separation. In applications, for space gravitational wave detection, our
+results for the residual gas damping coefficient for the 4TM torsion balance
+experiment is the closest one to the experimental and simulation data compared
+to previous models. For the LISA mission, our estimation for residual gas
+acceleration noise at the sensitive axis is consistent with the simulation
+result, within about $5\%$ difference. In addition, in the test of the
+gravitational inverse-square law, our results suggest that the constraint on
+the distance between TM and the conducting membrane can be reduced by about
+$28\%$.",2401.04808v1
+2010-09-20,Diffusive properties of persistent walks on cubic lattices with application to periodic Lorentz gases,"We calculate the diffusion coefficients of persistent random walks on cubic
+and hypercubic lattices, where the direction of a walker at a given step
+depends on the memory of one or two previous steps. These results are then
+applied to study a billiard model, namely a three-dimensional periodic Lorentz
+gas. The geometry of the model is studied in order to find the regimes in which
+it exhibits normal diffusion. In this regime, we calculate numerically the
+transition probabilities between cells to compare the persistent random-walk
+approximation with simulation results for the diffusion coefficient.",1009.3922v1
+2012-11-13,Critical exponent for the semilinear wave equation with scale invariant damping,"In this paper we consider the critical exponent problem for the semilinear
+damped wave equation with time-dependent coefficients. We treat the scale
+invariant cases. In this case the asymptotic behavior of the solution is very
+delicate and the size of coefficient plays an essential role. We shall prove
+that if the power of the nonlinearity is greater than the Fujita exponent, then
+there exists a unique global solution with small data, provided that the size
+of the coefficient is sufficiently large. We shall also prove some blow-up
+results even in the case that the coefficient is sufficiently small.",1211.2900v1
+2010-12-07,Turbulence damping as a measure of the flow dimensionality,"The dimensionality of turbulence in fluid layers determines their properties.
+We study electromagnetically driven flows in finite depth fluid layers and show
+that eddy viscosity, which appears as a result of three-dimensional motions,
+leads to increased bottom damping. The anomaly coefficient, which characterizes
+the deviation of damping from the one derived using a quasi-two-dimensional
+model, can be used as a measure of the flow dimensionality. Experiments in
+turbulent layers show that when the anomaly coefficient becomes high, the
+turbulent inverse energy cascade is suppressed. In the opposite limit
+turbulence can self-organize into a coherent flow.",1012.1371v1
+2012-01-05,Damped bead on a rotating circular hoop - a bifurcation zoo,"The evergreen problem of a bead on a rotating hoop shows a multitude of
+bifurcations when the bead moves with friction. This motion is studied for
+different values of the damping coefficient and rotational speeds of the hoop.
+Phase portraits and trajectories corresponding to all different modes of motion
+of the bead are presented. They illustrate the rich dynamics associated with
+this simple system. For some range of values of the damping coefficient and
+rotational speeds of the hoop, linear stability analysis of the equilibrium
+points is inadequate to classify their nature. A technique involving
+transformation of coordinates and order of magnitude arguments is presented to
+examine such cases. This may provide a general framework to investigate other
+complex systems.",1201.1218v1
+2015-08-24,Scaling variables and asymptotic profiles for the semilinear damped wave equation with variable coefficients,"We study the asymptotic behavior of solutions for the semilinear damped wave
+equation with variable coefficients. We prove that if the damping is effective,
+and the nonlinearity and other lower order terms can be regarded as
+perturbations, then the solution is approximated by the scaled Gaussian of the
+corresponding linear parabolic problem. The proof is based on the scaling
+variables and energy estimates.",1508.05778v3
+2018-07-17,On the blow-up for critical semilinear wave equations with damping in the scattering case,"We consider the Cauchy problem for semilinear wave equations with variable
+coefficients and time-dependent scattering damping in $\mathbf{R}^n$, where
+$n\geq 2$. It is expected that the critical exponent will be Strauss' number
+$p_0(n)$, which is also the one for semilinear wave equations without damping
+terms. Lai and Takamura (2018) have obtained the blow-up part, together with
+the upper bound of lifespan, in the sub-critical case $p<p_0(n)$. In this
+paper, we extend their results to the critical case $p=p_0(n)$. The proof is
+based on Wakasa and Yordanov (2018), which concerns the blow-up and upper bound
+of lifespan for critical semilinear wave equations with variable coefficients.",1807.06164v1
+2013-09-19,Van der Waals Coefficients for the Alkali-metal Atoms in the Material Mediums,"The damping coefficients for the alkali atoms are determined very accurately
+by taking into account the optical properties of the atoms and three distinct
+types of trapping materials such as Au (metal), Si (semi-conductor) and
+vitreous SiO2 (dielectric). Dynamic dipole polarizabilities are calculated
+precisely for the alkali atoms that reproduce the damping coefficients in the
+perfect conducting medium within 0.2% accuracy. Upon the consideration of the
+available optical data of the above wall materials, the damping coefficients
+are found to be substantially different than those of the ideal conductor. We
+also evaluated dispersion coefficients for the alkali dimers and compared them
+with the previously reported values. These coefficients are fitted into a
+ready-to-use functional form to aid the experimentalists the interaction
+potentials only with the knowledge of distances.",1309.4897v1
+2001-03-30,Thermal magnetization fluctuations in thin films and a new physical form for magnetization damping,"The effect of thermal fluctuations on a thin film magnetoresistive element
+has been calculated. The technique involves adding to the basic spin dynamics a
+general form of interaction with a thermal bath. For a general anisotropic
+magnetic system the resulting equation can be written as a Langevin equation
+for a harmonic oscillator. Our approach predicts two times smaller noise power
+at low frequencies than the conventional stochastic Landau-Lifshitz-Gilbert
+equation. It is shown that equivalent results can be obtained by introducing a
+tensor phenomenological damping term to the gyromagnetic dynamics driven by a
+thermal fluctuating field.",0103624v3
+2004-02-03,First-principles study of magnetization relaxation enhancement and spin-transfer in thin magnetic films,"The interface-induced magnetization damping of thin ferromagnetic films in
+contact with normal-metal layers is calculated from first principles for clean
+and disordered Fe/Au and Co/Cu interfaces. Interference effects arising from
+coherent scattering turn out to be very small, consistent with a very small
+magnetic coherence length. Because the mixing conductances which govern the
+spin transfer are to a good approximation real valued, the spin pumping can be
+described by an increased Gilbert damping factor but an unmodified gyromagnetic
+ratio. The results also confirm that the spin-current induced magnetization
+torque is an interface effect.",0402088v2
+2005-02-28,Magnetization dynamics of two interacting spins in an external magnetic field,"The longitudinal relaxation time of the magnetization of a system of two
+exchange coupled spins subjected to a strong magnetic field is calculated
+exactly by averaging the stochastic Gilbert-Landau-Lifshitz equation for the
+magnetization, i.e., the Langevin equation of the process, over its
+realizations so reducing the problem to a system of linear
+differential-recurrence relations for the statistical moments (averaged
+spherical harmonics). The system is solved in the frequency domain by matrix
+continued fractions yielding the complete solution of the two-spin problem in
+external fields for all values of the damping and barrier height parameters.
+The magnetization relaxation time extracted from the exact solution is compared
+with the inverse relaxation rate from Langer's theory of the decay of
+metastable states, which yields in the high barrier and intermediate-to-high
+damping limits the asymptotic behaviour of the greatest relaxation time.",0502661v2
+2007-06-28,Coherent Magnetization Precession in GaMnAs induced by Ultrafast Optical Excitation,"We use femtosecond optical pulses to induce, control and monitor
+magnetization precession in ferromagnetic Ga0.965Mn0.035As. At temperatures
+below ~40 K we observe coherent oscillations of the local Mn spins, triggered
+by an ultrafast photoinduced reorientation of the in-plane easy axis. The
+amplitude saturation of the oscillations above a certain pump intensity
+indicates that the easy axis remains unchanged above ~TC/2. We find that the
+observed magnetization precession damping (Gilbert damping) is strongly
+dependent on pump laser intensity, but largely independent on ambient
+temperature. We provide a physical interpretation of the observed light-induced
+collective Mn-spin relaxation and precession.",0706.4270v2
+2008-02-14,Light-induced magnetization precession in GaMnAs,"We report dynamics of the transient polar Kerr rotation (KR) and of the
+transient reflectivity induced by femtosecond laser pulses in ferromagnetic
+(Ga,Mn)As with no external magnetic field applied. It is shown that the
+measured KR signal consist of several different contributions, among which only
+the oscillatory signal is directly connected with the ferromagnetic order in
+(Ga,Mn)As. The origin of the light-induced magnetization precession is
+discussed and the magnetization precession damping (Gilbert damping) is found
+to be strongly influenced by annealing of the sample.",0802.2043v2
+2008-09-17,Spin-transfer torque induced reversal in magnetic domains,"Using the complex stereographic variable representation for the macrospin,
+from a study of the nonlinear dynamics underlying the generalized
+Landau-Lifshitz(LL) equation with Gilbert damping, we show that the
+spin-transfer torque is effectively equivalent to an applied magnetic field. We
+study the macrospin switching on a Stoner particle due to spin-transfer torque
+on application of a spin polarized current. We find that the switching due to
+spin-transfer torque is a more effective alternative to switching by an applied
+external field in the presence of damping. We demonstrate numerically that a
+spin-polarized current in the form of a short pulse can be effectively employed
+to achieve the desired macro-spin switching.",0809.2910v1
+2009-12-30,Spin torque and critical currents for magnetic vortex nano-oscillator in nanopillars,"We calculated the main dynamic parameters of the spin polarized current
+induced magnetic vortex oscillations in nanopillars, such as the range of
+current density, where a vortex steady oscillations exist, the oscillation
+frequency and orbit radius. We accounted for both the non-linear vortex
+frequency and non-linear vortex damping. To describe the vortex excitations by
+the spin polarized current we used a generalized Thiele approach to motion of
+the vortex core as a collective coordinate. All the calculation results are
+represented via the free layer sizes, saturation magnetization, Gilbert damping
+and the degree of the spin polarization of the fixed layer. Predictions of the
+developed model can be checked experimentally.",0912.5521v1
+2010-10-01,Ferromagnetic resonance study of Co/Pd/Co/Ni multilayers with perpendicular anisotropy irradiated with Helium ions,"We present a ferromagnetic resonance (FMR) study of the effect of Helium ion
+irradiation on the magnetic anisotropy, the linewidth and the Gilbert damping
+of a Co/Ni multilayer coupled to Co/Pd bilayers. The perpendicular magnetic
+anisotropy decreases linearly with He ion fluence, leading to a transition to
+in-plane magnetization at a critical fluence of 5x10^{14} ions/cm^2. We find
+that the damping is nearly independent of fluence but the FMR linewidth at
+fixed frequency has a maximum near the critical fluence, indicating that the
+inhomogeneous broadening of the FMR line is a non-monotonic function of the He
+ion fluence. Based on an analysis of the angular dependence of the FMR
+linewidth, the inhomogeneous broadening is associated with spatial variations
+in the magnitude of the perpendicular magnetic anisotropy. These results
+demonstrate that ion irradiation may be used to systematically modify the
+magnetic anisotropy and distribution of magnetic anisotropy parameters of
+Co/Pd/Co/Ni multilayers for applications and basic physics studies.",1010.0268v2
+2010-11-23,Ultra-fast magnetisation rates within the Landau-Lifshitz-Bloch model,"The ultra-fast magnetisation relaxation rates during the laser-induced
+magnetisation process are analyzed in terms of the Landau-Lifshitz-Bloch (LLB)
+equation for different values of spin $S$. The LLB equation is equivalent in
+the limit $S \rightarrow \infty$ to the atomistic Landau-Lifshitz-Gilbert (LLG)
+Langevin dynamics and for $S=1/2$ to the M3TM model [B. Koopmans, {\em et al.}
+Nature Mat. \textbf{9} (2010) 259]. Within the LLB model the ultra-fast
+demagnetisation time ($\tau_{M}$) and the transverse damping ($\alpha_{\perp}$)
+are parameterized by the intrinsic coupling-to-the-bath parameter $\lambda$,
+defined by microscopic spin-flip rate. We show that for the phonon-mediated
+Elliott-Yafet mechanism, $\lambda$ is proportional to the ratio between the
+non-equilibrium phonon and electron temperatures.
+  We investigate the influence of the finite spin number and the scattering
+rate parameter $\lambda$ on the magnetisation relaxation rates. The relation
+between the fs demagnetisation rate and the LLG damping, provided by the LLB
+theory, is checked basing on the available experimental data. A good agreement
+is obtained for Ni, Co and Gd favoring the idea that the same intrinsic
+scattering process is acting on the femtosecond and nanosecond timescale.",1011.5054v1
+2011-10-15,Atomistic spin dynamic method with both damping and moment of inertia effects included from first principles,"We consider spin dynamics for implementation in an atomistic framework and we
+address the feasibility of capturing processes in the femtosecond regime by
+inclusion of moment of inertia. In the spirit of an {\it s-d} -like interaction
+between the magnetization and electron spin, we derive a generalized equation
+of motion for the magnetization dynamics in the semi-classical limit, which is
+non-local in both space and time. Using this result we retain a generalized
+Landau-Lifshitz-Gilbert equation, also including the moment of inertia, and
+demonstrate how the exchange interaction, damping, and moment of inertia, all
+can be calculated from first principles.",1110.3387v2
+2011-10-24,CoB/Ni-Based Multilayer Nanowire with High-Speed Domain Wall Motion under Low Current Control,"The spin-transfer torque motion of magnetic domain walls (DWs) in a
+CoB/Ni-based nanowire driven by a low current density of
+(1.12\pm0.8)\times10^{11} A m^{-2} has been observed indirectly by
+magnetotransport measurements. A high DW velocity of 85\pm4 m/s at zero field
+was measured at the threshold current density. Upon increasing the current
+density to 2.6\times10^{11} A m^{-2}, the DW velocity increases to 197\pm16 m/s
+before decreasing quickly in the high-current-density regime attributed to
+nonadiabatic spin-transfer torque at a low damping factor and weak pinning. The
+addition of B atoms to the Co layers decreased the magnitude of saturation
+magnetization, Gilbert damping factor, and density of pinning sites, making the
+CoB/Ni multilayer nanowire favorable for practical applications.",1110.5112v3
+2012-09-17,Nonlinear emission of spin-wave caustics from an edge mode of a micro-structured Co2Mn0.6Fe0.4Si waveguide,"Magnetic Heusler materials with very low Gilbert damping are expected to show
+novel magnonic transport phenomena. We report nonlinear generation of higher
+harmonics leading to the emission of caustic spin-wave beams in a low-damping,
+micro-structured Co2Mn0.6Fe0.4Si Heusler waveguide. The source for the higher
+harmonic generation is a localized edge mode formed by the strongly
+inhomogeneous field distribution at the edges of the spin-wave waveguide. The
+radiation characteristics of the propagating caustic waves observed at twice
+and three times the excitation frequency are described by an analytical
+calculation based on the anisotropic dispersion of spin waves in a magnetic
+thin film.",1209.3669v2
+2013-07-10,"Scaling of spin Hall angle in 3d, 4d and 5d metals from Y3Fe5O12/metal spin pumping","Pure spin currents generated by spin pumping in ferromagnet/nonmagnet (FM/NM)
+bilayers produce inverse spin Hall effect (ISHE) voltages in the NM, from which
+spin pumping and transport characteristics of the NM can be extracted. Due to
+its exceptionally low damping, Y3Fe5O12 (YIG) is an important and widely used
+FM for microwave devices and ferromagnetic resonance (FMR) spin pumping. Here
+we report systematic investigation of spin pumping from 20-nm thick YIG thin
+films to a series of 3d, 4d and 5d normal metals (Cu, Ag, Ta, W, Pt and Au)
+with various spin-orbit coupling strengths. From enhanced Gilbert damping
+obtained from the frequency dependence of FMR linewidths and ISHE signals, the
+spin Hall angles and YIG/NM interfacial spin mixing conductances are
+quantitatively determined for these metals. The spin Hall angles largely vary
+as the fourth power of the atomic number, corroborating the dominant role of
+spin-orbit coupling across a broad range in the inverse spin Hall effect.",1307.2648v2
+2013-11-25,Spin-wave excitation and propagation in microstructured waveguides of yttrium iron garnet (YIG)/Pt bilayers,"We present an experimental study of spin-wave excitation and propagation in
+microstructured waveguides patterned from a 100 nm thick yttrium iron garnet
+(YIG)/platinum (Pt) bilayer. The life time of the spin waves is found to be
+more than an order of magnitude higher than in comparably sized metallic
+structures despite the fact that the Pt capping enhances the Gilbert damping.
+Utilizing microfocus Brillouin light scattering spectroscopy, we reveal the
+spin-wave mode structure for different excitation frequencies. An exponential
+spin-wave amplitude decay length of 31 {\mu}m is observed which is a
+significant step towards low damping, insulator based micro-magnonics.",1311.6305v1
+2014-10-02,Investigation of the temperature-dependence of ferromagnetic resonance and spin waves in Co2FeAl0.5Si0.5,"Co2FeAl0.5Si0.5 (CFAS) is a Heusler compound that is of interest for
+spintronics applications, due to its high spin polarization and relatively low
+Gilbert damping constant. In this study, the behavior of ferromagnetic
+resonance as a function of temperature was investigated in CFAS, yielding a
+decreasing trend of damping constant as the temperature was increased from 13
+to 300 K. Furthermore, we studied spin waves in CFAS using both frequency
+domain and time domain techniques, obtaining group velocities and attenuation
+lengths as high as 26 km/s and 23.3 um, respectively, at room temperature.",1410.0439v1
+2014-12-12,Spin waves in micro-structured yttrium iron garnet nanometer-thick films,"We investigated the spin-wave propagation in a micro-structured yttrium iron
+garnet waveguide of $40$ nm thickness. Utilizing spatially-resolved Brillouin
+light scattering microscopy, an exponential decay of the spin-wave amplitude of
+$(10.06 \pm 0.83)$ $\mu$m was observed. This leads to an estimated Gilbert
+damping constant of $\alpha=(8.79\pm 0.73)\times 10^{-4}$, which is larger than
+damping values obtained through ferromagnetic resonance measurements in
+unstructured films. The theoretically calculated spatial interference of
+waveguide modes was compared to the spin-wave pattern observed experimentally
+by means of Brillouin light scattering spectroscopy.",1412.4032v1
+2016-04-16,A broadband Ferromagnetic Resonance dipper probe for magnetic damping measurements from 4.2 K to 300 K,"A dipper probe for broadband Ferromagnetic Resonance (FMR) operating from 4.2
+K to room temperature is described. The apparatus is based on a 2-port
+transmitted microwave signal measurement with a grounded coplanar waveguide.
+The waveguide generates a microwave field and records the sample response. A
+3-stage dipper design is adopted for fast and stable temperature control. The
+temperature variation due to FMR is in the milli-Kelvin range at liquid helium
+temperature. We also designed a novel FMR probe head with a spring-loaded
+sample holder. Improved signal-to-noise ratio and stability compared to a
+common FMR head are achieved. Using a superconducting vector magnet we
+demonstrate Gilbert damping measurements on two thin film samples using a
+vector network analyzer with frequency up to 26 GHz: 1) A Permalloy film of 5
+nm thickness and 2) a CoFeB film of 1.5 nm thickness. Experiments were
+performed with the applied magnetic field parallel and perpendicular to the
+film plane.",1604.04688v1
+2016-05-27,A reduced model for precessional switching of thin-film nanomagnets under the influence of spin-torque,"We study the magnetization dynamics of thin-film magnetic elements with
+in-plane magnetization subject to a spin-current flowing perpendicular to the
+film plane. We derive a reduced partial differential equation for the in-plane
+magnetization angle in a weakly damped regime. We then apply this model to
+study the experimentally relevant problem of switching of an elliptical element
+when the spin-polarization has a component perpendicular to the film plane,
+restricting the reduced model to a macrospin approximation. The macrospin
+ordinary differential equation is treated analytically as a weakly damped
+Hamiltonian system, and an orbit-averaging method is used to understand
+transitions in solution behaviors in terms of a discrete dynamical system. The
+predictions of our reduced model are compared to those of the full
+Landau--Lifshitz--Gilbert--Slonczewski equation for a macrospin.",1605.08698v1
+2016-06-21,Torsion Effects and LLG Equation,"Based on the non-relativistic regime of the Dirac equation coupled to a
+torsion pseudo-vector, we study the dynamics of magnetization and how it is
+affected by the presence of torsion. We consider that torsion interacting terms
+in Dirac equation appear in two ways one of these is thhrough the covariant
+derivative considering the spin connection and gauge magnetic field and the
+other is through a non-minimal spin torsion coupling. We show within this
+framework, that it is possible to obtain the most general Landau, Lifshitz and
+Gilbert (LLG) equation including the torsion effects, where we refer to torsion
+as a geometric field playing an important role in the spin coupling process. We
+show that the torsion terms can give us two important landscapes in the
+magnetization dynamics: one of them related with damping and the other related
+with the screw dislocation that give us a global effect like a helix damping
+sharped. These terms are responsible for changes in the magnetization
+precession dynamics.",1606.06610v1
+2016-07-05,Magnetic moment of inertia within the breathing model,"An essential property of magnetic devices is the relaxation rate in magnetic
+switching which strongly depends on the energy dissipation and magnetic inertia
+of the magnetization dynamics. Both parameters are commonly taken as a
+phenomenological entities. However very recently, a large effort has been
+dedicated to obtain Gilbert damping from first principles. In contrast, there
+is no ab initio study that so far has reproduced measured data of magnetic
+inertia in magnetic materials. In this letter, we present and elaborate on a
+theoretical model for calculating the magnetic moment of inertia based on the
+torque-torque correlation model. Particularly, the method has been applied to
+bulk bcc Fe, fcc Co and fcc Ni in the framework of the tight-binding
+approximation and the numerical values are comparable with recent experimental
+measurements. The theoretical results elucidate the physical origin of the
+moment of inertia based on the electronic structure. Even though the moment of
+inertia and damping are produced by the spin-orbit coupling, our analysis shows
+that they are caused by undergo different electronic structure mechanisms.",1607.01307v1
+2016-10-14,Nambu mechanics for stochastic magnetization dynamics,"The Landau-Lifshitz-Gilbert (LLG) equation describes the dynamics of a damped
+magnetization vector that can be understood as a generalization of Larmor spin
+precession. The LLG equation cannot be deduced from the Hamiltonian framework,
+by introducing a coupling to a usual bath, but requires the introduction of
+additional constraints. It is shown that these constraints can be formulated
+elegantly and consistently in the framework of dissipative Nambu mechanics.
+This has many consequences for both the variational principle and for
+topological aspects of hidden symmetries that control conserved quantities. We
+particularly study how the damping terms of dissipative Nambu mechanics affect
+the consistent interaction of magnetic systems with stochastic reservoirs and
+derive a master equation for the magnetization. The proposals are supported by
+numerical studies using symplectic integrators that preserve the topological
+structure of Nambu equations. These results are compared to computations
+performed by direct sampling of the stochastic equations and by using closure
+assumptions for the moment equations, deduced from the master equation.",1610.04598v2
+2017-01-31,"Lack of correlation between the spin mixing conductance and the ISHE-generated voltages in CoFeB/Pt,Ta bilayers","We investigate spin pumping phenomena in polycrystalline CoFeB/Pt and
+CoFeB/Ta bilayers and the correlation between the effective spin mixing
+conductance $g^{\uparrow\downarrow}_{\rm eff}$ and the obtained voltages
+generated by the spin-to-charge current conversion via the inverse spin Hall
+effect in the Pt and Ta layers. For this purpose we measure the in-plane
+angular dependence of the generated voltages on the external static magnetic
+field and we apply a model to separate the spin pumping signal from the one
+generated by the spin rectification effect in the magnetic layer. Our results
+reveal a dominating role of anomalous Hall effect for the spin rectification
+effect with CoFeB and a lack of correlation between
+$g^{\uparrow\downarrow}_{\rm eff}$ and inverse spin Hall voltages pointing to a
+strong role of the magnetic proximity effect in Pt in understanding the
+observed increased damping. This is additionally reflected on the presence of a
+linear dependency of the Gilbert damping parameter on the Pt thickness.",1701.09110v1
+2017-06-05,Consistent microscopic analysis of spin pumping effects,"We present a consistent microscopic study of spin pumping effects for both
+metallic and insulating ferromagnets. As for metallic case, we present a simple
+quantum mechanical picture of the effect as due to the electron spin flip as a
+result of a nonadiabatic (off-diagonal) spin gauge field. The effect of
+interface spin-orbit interaction is briefly discussed. We also carry out
+field-theoretic calculation to discuss on the equal footing the spin current
+generation and torque effects such as enhanced Gilbert damping constant and
+shift of precession frequency both in metallic and insulating cases. For thick
+ferromagnetic metal, our study reproduces results of previous theories such as
+the correspondence between the dc component of the spin current and enhancement
+of the damping. For thin metal and insulator, the relation turns out to be
+modified. For the insulating case, driven locally by interface $sd$ exchange
+interaction due to magnetic proximity effect, physical mechanism is distinct
+from the metallic case. Further study of proximity effect and interface
+spin-orbit interaction would be crucial to interpret experimental results in
+particular for insulators.",1706.01185v1
+2018-03-04,Optimization of Time-Resolved Magneto-optical Kerr Effect Signals for Magnetization Dynamics Measurements,"Recently magnetic storage and magnetic memory have shifted towards the use of
+magnetic thin films with perpendicular magnetic anisotropy (PMA). Understanding
+the magnetic damping in these materials is crucial, but normal Ferromagnetic
+Resonance (FMR) measurements face some limitations. The desire to quantify the
+damping in materials with PMA has resulted in the adoption of Time-Resolved
+Magneto-optical Kerr Effect (TR-MOKE) measurements. In this paper, we discuss
+the angle and field dependent signals in TR-MOKE, and utilize a numerical
+algorithm based on the Landau-Lifshitz-Gilbert (LLG) equation to provide
+information on the optimal conditions to run TR-MOKE measurements.",1803.01280v2
+2018-05-04,Superparamagnetic Relaxation Driven by Colored Noise,"A theoretical investigation of magnetic relaxation processes in single domain
+particles driven by colored noise is presented. Two approaches are considered;
+the Landau-Lifshitz-Miyazaki-Seki equation, which is a Langevin dynamics model
+based on the introduction of an Ornstein-Uhlenbeck correlated noise into the
+Landau-Lifshitz-Gilbert equation and a Generalized Master Equation approach
+whereby the ordinary Master Equation is modified through the introduction of an
+explicit memory kernel. It is found that colored noise is likely to become
+important for high anisotropy materials where the characteristic system time,
+in this case the inverse Larmor precession frequency, becomes comparable to the
+correlation time. When the escape time is much longer than the correlation
+time, the relaxation profile of the spin has a similar exponential form to the
+ordinary LLG equation, while for low barrier heights and intermediate damping,
+for which the correlation time is a sizable fraction of the escape time, an
+unusual bi-exponential decay is predicted as a characteristic of colored noise.
+At very high damping and correlation times, the time profile of the spins
+exhibits a more complicated, noisy trajectory.",1805.01776v2
+2018-06-02,Ultra-low damping insulating magnetic thin films get perpendicular,"A magnetic material combining low losses and large Perpendicular Magnetic
+Anisotropy (PMA) is still a missing brick in the magnonic and spintronic
+fields. We report here on the growth of ultrathin Bismuth doped
+Y$_{3}$Fe$_{5}$O$_{12}$ (BiYIG) films on Gd$_{3}$Ga$_{5}$O$_{12}$ (GGG) and
+substituted GGG (sGGG) (111) oriented substrates. A fine tuning of the PMA is
+obtained using both epitaxial strain and growth induced anisotropies. Both
+spontaneously in-plane and out-of-plane magnetized thin films can be
+elaborated. Ferromagnetic Resonance (FMR) measurements demonstrate the high
+dynamic quality of these BiYIG ultrathin films, PMA films with Gilbert damping
+values as low as 3 10$^{-4}$ and FMR linewidth of 0.3 mT at 8 GHz are achieved
+even for films that do not exceed 30 nm in thickness. Moreover, we measure
+Inverse Spin Hall Effect (ISHE) on Pt/BiYIG stacks showing that the magnetic
+insulator$'$s surface is transparent to spin current making it appealing for
+spintronic applications.",1806.00658v1
+2018-06-12,"Dynamical and current-induced Dzyaloshinskii-Moriya interaction: Role for damping, gyromagnetism, and current-induced torques in noncollinear magnets","Both applied electric currents and magnetization dynamics modify the
+Dzyaloshinskii-Moriya interaction (DMI), which we call current-induced DMI
+(CIDMI) and dynamical DMI (DDMI), respectively. We report a theory of CIDMI and
+DDMI. The inverse of CIDMI consists in charge pumping by a time-dependent
+gradient of magnetization $\partial^2 M(r,t)/\partial r\partial t$, while the
+inverse of DDMI describes the torque generated by $\partial^2 M(r,t)/\partial
+r\partial t$. In noncollinear magnets CIDMI and DDMI depend on the local
+magnetization direction. The resulting spatial gradients correspond to torques
+that need to be included into the theories of Gilbert damping, gyromagnetism,
+and current-induced torques (CITs) in order to satisfy the Onsager reciprocity
+relations. CIDMI is related to the modification of orbital magnetism induced by
+magnetization dynamics, which we call dynamical orbital magnetism (DOM), and
+spatial gradients of DOM contribute to charge pumping. We present applications
+of this formalism to the CITs and to the torque-torque correlation in textured
+Rashba ferromagnets.",1806.04782v3
+2018-10-11,"Propagating spin waves in nanometer-thick yttrium iron garnet films: Dependence on wave vector, magnetic field strength and angle","We present a comprehensive investigation of propagating spin waves in
+nanometer-thick yttrium iron garnet (YIG) films. We use broadband spin-wave
+spectroscopy with integrated coplanar waveguides (CPWs) and microstrip antennas
+on top of continuous and patterned YIG films to characterize spin waves with
+wave vectors up to 10 rad/$\mu$m. All films are grown by pulsed laser
+deposition. From spin-wave transmission spectra, parameters such as the Gilbert
+damping constant, spin-wave dispersion relation, group velocity, relaxation
+time, and decay length are derived and their dependence on magnetic bias field
+strength and angle is systematically gauged. For a 40-nm-thick YIG film, we
+obtain a damping constant of $3.5 \times 10^{-4}$ and a maximum decay length of
+1.2 mm. Our experiments reveal a strong variation of spin-wave parameters with
+magnetic bias field and wave vector. Spin-wave properties change considerably
+up to a magnetic bias field of about 30 mT and above a field angle of
+$\theta_{H} = 20^{\circ}$, where $\theta_{H} = 0^{\circ}$ corresponds to the
+Damon-Eshbach configuration.",1810.04973v1
+2019-05-30,Predicting New Iron Garnet Thin Films with Perpendicular Magnetic Anisotropy,"Perpendicular magnetic anisotropy (PMA) is a necessary condition for many
+spintronic applications like spin-orbit torques switching, logic and memory
+devices. An important class of magnetic insulators with low Gilbert damping at
+room temperature are iron garnets, which only have a few PMA types such as
+terbium and samarium iron garnet. More and stable PMA garnet options are
+necessary for researchers to be able to investigate new spintronic phenomena.
+In this study, we predict 20 new substrate/magnetic iron garnet film pairs with
+stable PMA at room temperature. The effective anisotropy energies of 10
+different garnet films that are lattice-matched to 5 different commercially
+available garnet substrates have been calculated using shape, magnetoelastic
+and magnetocrystalline anisotropy terms. Strain type, tensile or compressive
+depending on substrate choice, as well as the sign and the magnitude of the
+magnetostriction constants of garnets determine if a garnet film may possess
+PMA. We show the conditions in which Samarium, Gadolinium, Terbium, Holmium,
+Dysprosium and Thulium garnets may possess PMA on the investigated garnet
+substrate types. Guidelines for obtaining garnet films with low damping are
+presented. New PMA garnet films with tunable saturation moment and field may
+improve spin-orbit torque memory and compensated magnonic thin film devices.",1905.13042v1
+2019-07-17,Inhomogeneous domain walls in spintronic nanowires,"In case of a spin-polarized current, the magnetization dynamics in nanowires
+are governed by the classical Landau-Lifschitz equation with Gilbert damping
+term, augmented by a typically non-variational Slonczewski term. Taking axial
+symmetry into account, we study the existence of domain wall type coherent
+structure solutions, with focus on one space dimension and spin-polarization,
+but our results also apply to vanishing spin-torque term. Using methods from
+bifurcation theory for arbitrary constant applied fields, we prove the
+existence of domain walls with non-trivial azimuthal profile, referred to as
+inhomogeneous. We present an apparently new type of domain wall, referred to as
+non-flat, whose approach of the axial magnetization has a certain oscillatory
+character. Additionally, we present the leading order mechanism for the
+parameter selection of flat and non-flat inhomogeneous domain walls for an
+applied field below a threshold, which depends on anisotropy, damping, and
+spin-transfer. Moreover, numerical continuation results of all these domain
+wall solutions are presented.",1907.07470v2
+2019-09-10,Spin Pumping from Permalloy into Uncompensated Antiferromagnetic Co doped Zinc Oxide,"Heterostructures of Co-doped ZnO and Permalloy were investigated for their
+static and dynamic magnetic interaction. The highly Co-doped ZnO is
+paramagentic at room temperature and becomes an uncompensated antiferromagnet
+at low temperatures, showing a narrowly opened hysteresis and a vertical
+exchange bias shift even in the absence of any ferromagnetic layer. At low
+temperatures in combination with Permalloy an exchange bias is found causing a
+horizontal as well as vertical shift of the hysteresis of the heterostructure
+together with an increase in coercive field. Furthermore, an increase in the
+Gilbert damping parameter at room temperature was found by multifrequency FMR
+evidencing spin pumping. Temperature dependent FMR shows a maximum in magnetic
+damping close to the magnetic phase transition. These measurements also
+evidence the exchange bias interaction of Permalloy and long-range ordered
+Co-O-Co structures in ZnO, that are barely detectable by SQUID due to the
+shorter probing times in FMR.",1909.04362v3
+2020-02-27,Ultrafast magnetization dynamics in half-metallic Co$_2$FeAl Heusler alloy,"We report on optically induced, ultrafast magnetization dynamics in the
+Heusler alloy $\mathrm{Co_{2}FeAl}$, probed by time-resolved magneto-optical
+Kerr effect. Experimental results are compared to results from electronic
+structure theory and atomistic spin-dynamics simulations. Experimentally, we
+find that the demagnetization time ($\tau_{M}$) in films of
+$\mathrm{Co_{2}FeAl}$ is almost independent of varying structural order, and
+that it is similar to that in elemental 3d ferromagnets. In contrast, the
+slower process of magnetization recovery, specified by $\tau_{R}$, is found to
+occur on picosecond time scales, and is demonstrated to correlate strongly with
+the Gilbert damping parameter ($\alpha$). Our results show that
+$\mathrm{Co_{2}FeAl}$ is unique, in that it is the first material that clearly
+demonstrates the importance of the damping parameter in the remagnetization
+process. Based on these results we argue that for $\mathrm{Co_{2}FeAl}$ the
+remagnetization process is dominated by magnon dynamics, something which might
+have general applicability.",2002.12255v1
+2020-06-05,Controlling the nonlinear relaxation of quantized propagating magnons in nanodevices,"Relaxation of linear magnetization dynamics is well described by the viscous
+Gilbert damping processes. However, for strong excitations, nonlinear damping
+processes such as the decay via magnon-magnon interactions emerge and trigger
+additional relaxation channels. Here, we use space- and time-resolved
+microfocused Brillouin light scattering spectroscopy and micromagnetic
+simulations to investigate the nonlinear relaxation of strongly driven
+propagating spin waves in yttrium iron garnet nanoconduits. We show that the
+nonlinear magnon relaxation in this highly quantized system possesses
+intermodal features, i.e., magnons scatter to higher-order quantized modes
+through a cascade of scattering events. We further show how to control such
+intermodal dissipation processes by quantization of the magnon band in
+single-mode devices, where this phenomenon approaches its fundamental limit.
+Our study extends the knowledge about nonlinear propagating spin waves in
+nanostructures which is essential for the construction of advanced spin-wave
+elements as well as the realization of Bose-Einstein condensates in scaled
+systems.",2006.03400v2
+2021-05-16,Anatomy of inertial magnons in ferromagnets,"We analyze dispersion relations of magnons in ferromagnetic nanostructures
+with uniaxial anisotropy taking into account inertial terms, i.e. magnetic
+nutation. Inertial effects are parametrized by damping-independent parameter
+$\beta$, which allows for an unambiguous discrimination of inertial effects
+from Gilbert damping parameter $\alpha$. The analysis of magnon dispersion
+relation shows its two branches are modified by the inertial effect, albeit in
+different ways. The upper nutation branch starts at $\omega=1/ \beta$, the
+lower branch coincides with FMR in the long-wavelength limit and deviates from
+the zero-inertia parabolic dependence $\simeq\omega_{FMR}+Dk^2$ of the exchange
+magnon. Taking a realistic experimental geometry of magnetic thin films,
+nanowires and nanodiscs, magnon eigenfrequencies, eigenvectors and $Q$-factors
+are found to depend on the shape anisotropy. The possibility of phase-matched
+magneto-elastic excitation of nutation magnons is discussed and the condition
+was found to depend on $\beta$, exchange stiffness $D$ and the acoustic
+velocity.",2105.07376v1
+2021-11-16,Ultrathin ferrimagnetic GdFeCo films with very low damping,"Ferromagnetic materials dominate as the magnetically active element in
+spintronic devices, but come with drawbacks such as large stray fields, and low
+operational frequencies. Compensated ferrimagnets provide an alternative as
+they combine the ultrafast magnetization dynamics of antiferromagnets with a
+ferromagnet-like spin-orbit-torque (SOT) behavior. However to use ferrimagnets
+in spintronic devices their advantageous properties must be retained also in
+ultrathin films (t < 10 nm). In this study, ferrimagnetic Gdx(Fe87.5Co12.5)1-x
+thin films in the thickness range t = 2-20 nm were grown on high resistance
+Si(100) substrates and studied using broadband ferromagnetic resonance
+measurements at room temperature. By tuning their stoichiometry, a nearly
+compensated behavior is observed in 2 nm Gdx(Fe87.5Co12.5)1-x ultrathin films
+for the first time, with an effective magnetization of Meff = 0.02 T and a low
+effective Gilbert damping constant of {\alpha} = 0.0078, comparable to the
+lowest values reported so far in 30 nm films. These results show great promise
+for the development of ultrafast and energy efficient ferrimagnetic spintronic
+devices.",2111.08768v1
+2021-11-30,First and second order magnetic anisotropy and damping of europium iron garnet under high strain,"Understanding and tailoring static and dynamic properties of magnetic
+insulator thin films is important for spintronic device applications. Here, we
+grow atomically flat epitaxial europium iron garnet (EuIG) thin films by pulsed
+laser deposition on (111)-oriented garnet substrates with a range of lattice
+parameters. By controlling the lattice mismatch between EuIG and the
+substrates, we tune the strain in EuIG films from compressive to tensile
+regime, which is characterized by X-ray diffraction. Using ferromagnetic
+resonance, we find that in addition to the first-order perpendicular magnetic
+anisotropy which depends linearly on the strain, there is a significant
+second-order one that has a quadratic strain dependence. Inhomogeneous
+linewidth of the ferromagnetic resonance increases notably with increasing
+strain, while the Gilbert damping parameter remains nearly constant (~
+2x10^-2). These results provide valuable insight into the spin dynamics in
+ferrimagnetic insulators and useful guidance for material synthesis and
+engineering of next-generation spintronics applications.",2111.15142v1
+2022-10-01,Nonlinear features of the superconductor--ferromagnet--superconductor $\varphi_0$ Josephson junction in ferromagnetic resonance region,"We demonstrate the manifestations of the nonlinear features in magnetic
+dynamics and IV-characteristics of the $\varphi_0$ Josephson junction in the
+ferromagnetic resonance region. We show that at small values of system
+parameters, namely, damping, spin-orbit interaction, and Josephson to magnetic
+energy ratio, the magnetic dynamics is reduced to the dynamics of the scalar
+Duffing oscillator, driven by the Josephson oscillations. The role of
+increasing superconducting current in the resonance region is clarified.
+Shifting of the ferromagnetic resonant frequency and the reversal of its
+damping dependence due to nonlinearity are demonstrated by the full
+Landau-Lifshitz-Gilbert-Josephson system of equations, and in its different
+approximations. Finally, we demonstrate the negative differential resistance in
+the IV--characteristics, and its correlation with the foldover effect.",2210.00366v1
+2023-12-16,Spin-torque nano-oscillator based on two in-plane magnetized synthetic ferrimagnets,"We report the dynamic characterization of the spin-torque-driven in-plane
+precession modes of a spin-torque nano-oscillator based on two different
+synthetic ferrimagnets: a pinned one characterized by a strong RKKY interaction
+which is exchange coupled to an antiferromagnetic layer; and a second one,
+non-pinned characterized by weak RKKY coupling. The microwave properties
+associated with the steady-state precession of both SyFs are characterized by
+high spectral purity and power spectral density. However, frequency dispersion
+diagrams of the damped and spin transfer torque modes reveal drastically
+different dynamical behavior and microwave emission properties in both SyFs. In
+particular, the weak coupling between the magnetic layers of the non-pinned SyF
+raises discontinuous dispersion diagrams suggesting a strong influence of mode
+crossing. An interpretation of the different dynamical features observed in the
+damped and spin torque modes of both SyF systems was obtained by solving
+simultaneously, in a macrospin approach, a linearized version of the
+Landau-Lifshitz-Gilbert equation including the spin transfer torque term.",2312.10451v2
+2020-10-02,Multilevel quasi-Monte Carlo for random elliptic eigenvalue problems I: Regularity and error analysis,"Stochastic PDE eigenvalue problems are useful models for quantifying the
+uncertainty in several applications from the physical sciences and engineering,
+e.g., structural vibration analysis, the criticality of a nuclear reactor or
+photonic crystal structures. In this paper we present a multilevel quasi-Monte
+Carlo (MLQMC) method for approximating the expectation of the minimal
+eigenvalue of an elliptic eigenvalue problem with coefficients that are given
+as a series expansion of countably-many stochastic parameters. The MLQMC
+algorithm is based on a hierarchy of discretisations of the spatial domain and
+truncations of the dimension of the stochastic parameter domain. To approximate
+the expectations, randomly shifted lattice rules are employed. This paper is
+primarily dedicated to giving a rigorous analysis of the error of this
+algorithm. A key step in the error analysis requires bounds on the mixed
+derivatives of the eigenfunction with respect to both the stochastic and
+spatial variables simultaneously. Under stronger smoothness assumptions on the
+parametric dependence, our analysis also extends to multilevel higher-order
+quasi-Monte Carlo rules. An accompanying paper [Gilbert and Scheichl, 2022],
+focusses on practical extensions of the MLQMC algorithm to improve efficiency,
+and presents numerical results.",2010.01044v4
+2021-03-05,Multilevel quasi-Monte Carlo for random elliptic eigenvalue problems II: Efficient algorithms and numerical results,"Stochastic PDE eigenvalue problems often arise in the field of uncertainty
+quantification, whereby one seeks to quantify the uncertainty in an eigenvalue,
+or its eigenfunction. In this paper we present an efficient multilevel
+quasi-Monte Carlo (MLQMC) algorithm for computing the expectation of the
+smallest eigenvalue of an elliptic eigenvalue problem with stochastic
+coefficients. Each sample evaluation requires the solution of a PDE eigenvalue
+problem, and so tackling this problem in practice is notoriously
+computationally difficult. We speed up the approximation of this expectation in
+four ways: we use a multilevel variance reduction scheme to spread the work
+over a hierarchy of FE meshes and truncation dimensions; we use QMC methods to
+efficiently compute the expectations on each level; we exploit the smoothness
+in parameter space and reuse the eigenvector from a nearby QMC point to reduce
+the number of iterations of the eigensolver; and we utilise a two-grid
+discretisation scheme to obtain the eigenvalue on the fine mesh with a single
+linear solve. The full error analysis of a basic MLQMC algorithm is given in
+the companion paper [Gilbert and Scheichl, 2022], and so in this paper we focus
+on how to further improve the efficiency and provide theoretical justification
+for using nearby QMC points and two-grid methods. Numerical results are
+presented that show the efficiency of our algorithm, and also show that the
+four strategies we employ are complementary.",2103.03407v3
+2014-08-15,Linear hyperbolic equations with time-dependent propagation speed and strong damping,"We consider a second order linear equation with a time-dependent coefficient
+c(t) in front of the ""elastic"" operator. For these equations it is well-known
+that a higher space-regularity of initial data compensates a lower
+time-regularity of c(t).
+  In this paper we investigate the influence of a strong dissipation, namely a
+friction term which depends on a power of the elastic operator.
+  What we discover is a threshold effect. When the exponent of the elastic
+operator in the friction term is greater than 1/2, the damping prevails and the
+equation behaves as if the coefficient c(t) were constant. When the exponent is
+less than 1/2, the time-regularity of c(t) comes into play. If c(t) is regular
+enough, once again the damping prevails. On the contrary, when c(t) is not
+regular enough the damping might be ineffective, and there are examples in
+which the dissipative equation behaves as the non-dissipative one. As expected,
+the stronger is the damping, the lower is the time-regularity threshold.
+  We also provide counterexamples showing the optimality of our results.",1408.3499v1
+2019-10-24,Topological damping Rashba spin orbit torque in ballistic magnetic domain walls,"Rashba spin orbit torque derived from the broken inversion symmetry at
+ferromagnet/heavy metal interfaces has potential application in spintronic
+devices. In conventional description of the precessional and damping components
+of the Rashba spin orbit torque in magnetization textures, the decomposition
+coefficients are assumed to be independent of the topology of the underlying
+structure. Contrary to this common wisdom, for Schr\""{o}dinger electrons
+trespassing ballistically across a magnetic domain wall, we found that the
+decomposition coefficient of the damping component is determined by the
+topology of the domain wall. The resultant damping Rashba spin orbit torque is
+protected by the topology of the underlying magnetic domain wall and robust
+against small deviations from the ideal domain wall profile. Our identification
+of a topological damping Rashba spin orbit torque component in magnetic domain
+walls will help to understand experiments on current driven domain wall motion
+in ferromagnet/heavy metal systems with broken inversion symmetry and to
+facilitate its utilization in innovative device designs.",1910.10977v2
+2023-10-14,Exploring Damping Effect of Inner Control Loops for Grid-Forming VSCs,"This paper presents an analytical approach to explore the damping effect of
+inner loops on grid-forming converters. First, an impedance model is proposed
+to characterize the behaviors of inner loops, thereby illustrating their
+influence on output impedance shaping. Then, based on the impedance
+representation, the complex torque coefficient method is employed to assess the
+contribution of inner loops to system damping. The interactions among inner
+loops, outer loops, and the ac grid are analyzed. It reveals that inner loops
+shape the electrical damping torque coefficient and consequently influence both
+synchronous and sub-synchronous oscillation modes. The virtual admittance and
+current control-based inner-loop scheme is employed to illustrate the proposed
+analytical approach. The case study comprises the analysis of impedance
+profiles, the analysis of damping torque contributed by inner loops under
+various grid strengths, and the comparison between dq-frame and
+{\alpha}\b{eta}-frame realizations of inner loops. Finally, simulation and
+experimental tests collaborate with theoretical approaches and findings.",2310.09660v1
+2003-01-30,Dynamic effects of electromagnetic wave on a damped two-level atom,"We studied the dynamic effects of an electromagnetic(EM) wave with circular
+polarization on a two-level damped atom. The results demonstrate interesting ac
+Stark split of energy levels of damped atom. The split levels have different
+energies and lifetimes, both of which depend on the interaction and the damping
+rate of atom. When the frequency of the EM wave is tuned to satisfy the
+resonance condition in the strong coupling limit, the transition probability
+exhibits Rabi oscillation. Momentum transfer between atom and EM wave shows
+similar properties as the transition probability under resonance condition. For
+a damped atom interacting with EM field, there exists no longer stable state.
+More importantly, if the angular frequency of the EM wave is tuned the same as
+the atomic transition frequency and its amplitude is adjusted appropriately
+according to the damping coefficients, we can prepare a particular 'Dressed
+State' of the coupled system between atom and EM field and can keep the system
+coherently in this 'Dressed state' for a very long time. This opens another way
+to prepare coherent atomic states.",0301166v1
+2014-03-13,The best decay rate of the damped plate equation in a square,"In this paper we study the best decay rate of the solutions of a damped plate
+equation in a square and with a homogeneous Dirichlet boundary conditions. We
+show that the fastest decay rate is given by the supremum of the real part of
+the spectrum of the infinitesimal generator of the underlying semigroup, if the
+damping coefficient is in $L^\infty(\Omega).$ Moreover, we give some numerical
+illustrations by spectral computation of the spectrum associated to the damped
+plate equation. The numerical results obtained for various cases of damping are
+in a good agreement with theoretical ones. Computation of the spectrum and
+energy of discrete solution of damped plate show that the best decay rate is
+given by spectral abscissa of numerical solution.",1403.3199v1
+2015-02-16,Role of nonlinear anisotropic damping in the magnetization dynamics of topological solitons,"The consequences of nonlinear anisotropic damping, driven by the presence of
+Rashba spin-orbit coupling in thin ferromagnetic metals, are examined for the
+dynamics of topological magnetic solitons such as domain walls, vortices, and
+skyrmions. The damping is found to affect Bloch and N\'eel walls differently in
+the steady state regime below Walker breakdown and leads to a monotonic
+increase in the wall velocity above this transition for large values of the
+Rashba coefficient. For vortices and skyrmions, a generalization of the damping
+tensor within the Thiele formalism is presented. It is found that chiral
+components of the damping affect vortex- and hedgehog-like skyrmions in
+different ways, but the dominant effect is an overall increase in the
+viscous-like damping.",1502.04695v2
+2016-05-29,Damped Infinite Energy Solutions of the 3D Euler and Boussinesq Equations,"We revisit a family of infinite-energy solutions of the 3D incompressible
+Euler equations proposed by Gibbon et al. [9] and shown to blowup in finite
+time by Constantin [6]. By adding a damping term to the momentum equation we
+examine how the damping coefficient can arrest this blowup. Further, we show
+that similar infinite-energy solutions of the inviscid 3D Boussinesq system
+with damping can develop a singularity in finite time as long as the damping
+effects are insufficient to arrest the (undamped) 3D Euler blowup in the
+associated damped 3D Euler system.",1605.08965v3
+2016-06-14,Anomalous Damping of a Micro-electro-mechanical Oscillator in Superfluid $^3$He-B,"The mechanical resonance properties of a micro-electro-mechanical oscillator
+with a gap of 1.25 $\mu$m was studied in superfluid $^3$He-B at various
+pressures. The oscillator was driven in the linear damping regime where the
+damping coefficient is independent of the oscillator velocity. The quality
+factor of the oscillator remains low ($Q\approx 80$) down to 0.1 $T_c$, 4
+orders of magnitude less than the intrinsic quality factor measured in vacuum
+at 4 K. In addition to the Boltzmann temperature dependent contribution to the
+damping, a damping proportional to temperature was found to dominate at low
+temperatures. We propose a multiple scattering mechanism of the surface Andreev
+bound states to be a possible cause for the anomalous damping.",1606.04483v2
+2019-09-21,Stability for coupled waves with locally disturbed Kelvin-Voigt damping,"We consider a coupled wave system with partial Kelvin-Voigt damping in the
+interval (-1,1), where one wave is dissipative and the other does not. When the
+damping is effective in the whole domain (-1,1) it was proven in H.Portillo
+Oquendo and P.Sanez Pacheco, optimal decay for coupled waves with Kelvin-voigt
+damping, Applied Mathematics Letters 67 (2017), 16-20. That the energy is
+decreasing over the time with a rate equal to $t^{-\frac{1}{2}}$. In this
+paper, using the frequency domain method we show the effect of the coupling and
+the non smoothness of the damping coefficient on the energy decay. Actually, as
+expected we show the lack of exponential stability, that the semigroup loses
+speed and it decays polynomially with a slower rate then given in, H.Portillo
+Oquendo and P.Sanez Pacheco, optimal decay for coupled waves with Kelvin-voigt
+damping, Applied Mathematics Letters 67 (2017), 16-20, down to zero at least as
+$t^{-\frac{1}{12}}$.",1909.09838v1
+2020-06-30,Polynomial stabilization of non-smooth direct/indirect elastic/viscoelastic damping problem involving Bresse system,"We consider an elastic/viscoelastic transmission problem for the Bresse
+system with fully Dirichlet or Dirichlet-Neumann-Neumann boundary conditions.
+The physical model consists of three wave equations coupled in certain pattern.
+The system is damped directly or indirectly by global or local Kelvin-Voigt
+damping. Actually, the number of the dampings, their nature of distribution
+(locally or globally) and the smoothness of the damping coefficient at the
+interface play a crucial role in the type of the stabilization of the
+corresponding semigroup. Indeed, using frequency domain approach combined with
+multiplier techniques and the construction of a new multiplier function, we
+establish different types of energy decay rate (see the table of stability
+results below). Our results generalize and improve many earlier ones in the
+literature and in particular some studies done on the Timoshenko system with
+Kelvin-Voigt damping.",2006.16595v2
+2021-12-13,Cosmic ray streaming in the turbulent interstellar medium,"We study the streaming instability of GeV$-100~$GeV cosmic rays (CRs) and its
+damping in the turbulent interstellar medium (ISM). We find that the damping of
+streaming instability is dominated by ion-neutral collisional damping in weakly
+ionized molecular clouds, turbulent damping in the highly ionized warm medium,
+and nonlinear Landau damping in the Galactic halo. Only in the Galactic halo,
+is the streaming speed of CRs close to the Alfv\'{e}n speed. Alfv\'{e}nic
+turbulence plays an important role in both suppressing the streaming
+instability and regulating the diffusion of streaming CRs via magnetic field
+line tangling, with the effective mean free path of streaming CRs in the
+observer frame determined by the Alfv\'{e}nic scale in super-Alfv\'{e}nic
+turbulence. The resulting diffusion coefficient is sensitive to Alfv\'{e}n Mach
+number, which has a large range of values in the multi-phase ISM.
+Super-Alfv\'{e}nic turbulence contributes to additional confinement of
+streaming CRs, irrespective of the dominant damping mechanism.",2112.06941v2
+2023-12-07,Probing levitodynamics with multi-stochastic forces and the simple applications on the dark matter detection in optical levitation experiment,"If the terrestrial environment is permeated by dark matter, the levitation
+experiences damping forces and fluctuations attributed to dark matter. This
+paper investigates levitodynamics with multiple stochastic forces, including
+thermal drag, photon recoil, feedback, etc., assuming that all of these forces
+adhere to the fluctuation-dissipation theorem. The ratio of total damping to
+the stochastic damping coefficient distinguishes the levitodynamics from cases
+involving only one single stochastic force. The heating and cooling processes
+are formulated to determine the limits of temperature change. All sources of
+stochastic forces are comprehensively examined, revealing that dark matter
+collisions cannot be treated analogously to fluid dynamics. Additionally, a
+meticulous analysis is presented, elucidating the intricate relationship
+between the fundamental transfer cross-section and the macroscopic transfer
+cross-section. While the dark damping coefficient is suppressed by the mass of
+the levitated particle, scattering can be coherently enhanced based on the
+scale of the component microscopic particle, the atomic form factor, and the
+static structure factor. Hence, dark damping holds the potential to provide
+valuable insights into the detection of the macroscopic strength of fundamental
+particles. We propose experimental procedures for levitation and employ linear
+estimation to extract the dark damping coefficient. Utilizing current
+levitation results, we demonstrate that the fundamental transfer cross section
+of dark matter can be of the order $\sigma^{\rm D}_{T}\lsim {\cal
+O}(10^{-26})\rm cm^2$.",2312.04202v2
+2013-08-17,Thickness and power dependence of the spin-pumping effect in Y3Fe5O12/Pt heterostructures measured by the inverse spin Hall effect,"The dependence of the spin-pumping effect on the yttrium iron garnet
+(Y3Fe5O12, YIG) thickness detected by the inverse spin Hall effect (ISHE) has
+been investigated quantitatively. Due to the spin-pumping effect driven by the
+magnetization precession in the ferrimagnetic insulator YIG film a
+spin-polarized electron current is injected into the Pt layer. This spin
+current is transformed into electrical charge current by means of the ISHE. An
+increase of the ISHE-voltage with increasing film thickness is observed and
+compared to the theoretically expected behavior. The effective damping
+parameter of the YIG/Pt samples is found to be enhanced with decreasing YIG
+film thickness. The investigated samples exhibit a spin mixing conductance of
+g=(7.43 \pm 0.36) \times 10^{18} m^{-2} and a spin Hall angle of theta_{ISHE} =
+0.009 \pm 0.0008. Furthermore, the influence of nonlinear effects on the
+generated voltage and on the Gilbert damping parameter at high excitation
+powers are revealed. It is shown that for small YIG film thicknesses a
+broadening of the linewidth due to nonlinear effects at high excitation powers
+is suppressed because of a lack of nonlinear multi-magnon scattering channels.
+We have found that the variation of the spin-pumping efficiency for thick YIG
+samples exhibiting pronounced nonlinear effects is much smaller than the
+nonlinear enhancement of the damping.",1308.3787v1
+2020-05-28,Spintronics meets nonadiabatic molecular dynamics: Geometric spin torque and damping on noncollinear classical magnetism due to electronic open quantum system,"We analyze a quantum-classical hybrid system of steadily precessing slow
+classical localized magnetic moments, forming a head-to-head domain wall,
+embedded into an open quantum system of fast nonequilibrium electrons. The
+electrons reside within a metallic wire connected to macroscopic reservoirs.
+The model captures the essence of dynamical noncollinear and noncoplanar
+magnetic textures in spintronics, while making it possible to obtain the exact
+time-dependent nonequilibrium density matrix of electronic system and split it
+into four contributions. The Fermi surface contribution generates dissipative
+(or damping-like in spintronics terminology) spin torque on the moments, and
+one of the two Fermi sea contributions generates geometric torque dominating in
+the adiabatic regime. When the coupling to the reservoirs is reduced, the
+geometric torque is the only nonzero contribution. Locally it has both
+nondissipative (or field-like in spintronics terminology) and damping-like
+components, but with the sum of latter being zero, which act as the
+counterparts of geometric magnetism force and electronic friction in
+nonadiabatic molecular dynamics. Such current-independent geometric torque is
+absent from widely used micromagnetics or atomistic spin dynamics modeling of
+magnetization dynamics based on the Landau-Lifshitz-Gilbert equation, where
+previous analysis of Fermi surface-type torque has severely underestimated its
+magnitude.",2005.14153v2
+2020-09-29,Structural Phase Dependent Giant Interfacial Spin Transparency in W/CoFeB Thin Film Heterostructure,"Pure spin current has transfigured the energy-efficient spintronic devices
+and it has the salient characteristic of transport of the spin angular
+momentum. Spin pumping is a potent method to generate pure spin current and for
+its increased efficiency high effective spin-mixing conductance (Geff) and
+interfacial spin transparency (T) are essential. Here, a giant T is reported in
+Sub/W(t)/Co20Fe60B20(d)/SiO2(2 nm) heterostructures in \beta-tungsten (\beta-W)
+phase by employing all-optical time-resolved magneto-optical Kerr effect
+technique. From the variation of Gilbert damping with W and CoFeB thicknesses,
+the spin diffusion length of W and spin-mixing conductances are extracted.
+Subsequently, T is derived as 0.81 \pm 0.03 for the \beta-W/CoFeB interface. A
+sharp variation of Geff and T with W thickness is observed in consonance with
+the thickness-dependent structural phase transition and resistivity of W. The
+spin memory loss and two-magnon scattering effects are found to have negligible
+contributions to damping modulation as opposed to spin pumping effect which is
+reconfirmed from the invariance of damping with Cu spacer layer thickness
+inserted between W and CoFeB. The observation of giant interfacial spin
+transparency and its strong dependence on crystal structures of W will be
+important for pure spin current based spin-orbitronic devices.",2009.14143v1
+2023-12-31,Molecular Hybridization Induced Antidamping and Sizable Enhanced Spin-to-Charge Conversion in Co20Fe60B20/$β$-W/C60 Heterostructures,"Development of power efficient spintronics devices has been the compelling
+need in the post-CMOS technology era. The effective tunability of
+spin-orbit-coupling (SOC) in bulk and at the interfaces of hybrid materials
+stacking is a prerequisite for scaling down the dimension and power consumption
+of these devices. In this work, we demonstrate the strong chemisorption of C60
+molecules when grown on the high SOC $\beta$-W layer. The parent CFB/$\beta$-W
+bilayer exhibits large spin-to-charge interconversion efficiency, which can be
+ascribed to the interfacial SOC observed at the Ferromagnet/Heavy metal
+interface. Further, the adsorption of C60 molecules on $\beta$-W reduces the
+effective Gilbert damping by $\sim$15% in the CFB/$\beta$-W/C60
+heterostructures. The anti-damping is accompanied by a gigantic $\sim$115%
+enhancement in the spin-pumping induced output voltage owing to the molecular
+hybridization. The non-collinear Density Functional Theory calculations confirm
+the long-range enhancement of SOC of $\beta$-W upon the chemisorption of C60
+molecules, which in turn can also enhance the SOC at the CFB/$\beta$-W
+interface in CFB/$\beta$-W/C60 heterostructures. The combined amplification of
+bulk as well interfacial SOC upon molecular hybridization stabilizes the
+anti-damping and enhanced spin-to-charge conversion, which can pave the way for
+the fabrication of power efficient spintronics devices.",2401.00486v1
+2011-01-28,Entanglement between two atoms in a damping Jaynes-Cummings model,"The entanglement between two atoms in a damping Jaynes-Cummings model is
+investigated with different decay coefficients of the atoms from the upper
+level to other levels under detuning between the atomic frequency and the
+quantized light field frequency. The results indicate that the larger the decay
+coefficient is, the more quickly the entanglement decays. The detuning enhances
+the entanglement's average value at long times. More importantly, the results
+show that the so-called sudden death effect can be avoided by enhancing the
+detuning or the decay coefficient.",1101.5522v1
+2015-05-27,Logarithmic stability in determining a boundary coefficient in an ibvp for the wave equation,"In [2] we introduced a method combining together an observability inequality
+and a spectral decomposition to get a logarithmic stability estimate for the
+inverse problem of determining both the potential and the damping coefficient
+in a dissipative wave equation from boundary measurements. The present work
+deals with an adaptation of that method to obtain a logarithmic stability
+estimate for the inverse problem of determining a boundary damping coefficient
+from boundary measurements. As in our preceding work, the different boundary
+measurements are generated by varying one of the initial conditions.",1505.07248v1
+2021-05-20,On the the critical exponent for the semilinear Euler-Poisson-Darboux-Tricomi equation with power nonlinearity,"In this note, we derive a blow-up result for a semilinear generalized Tricomi
+equation with damping and mass terms having time-dependent coefficients. We
+consider these coefficients with critical decay rates. Due to this threshold
+nature of the time-dependent coefficients (both for the damping and for the
+mass), the multiplicative constants appearing in these lower-order terms
+strongly influence the value of the critical exponent, determining a
+competition between a Fujita-type exponent and a Strauss-type exponent.",2105.09879v2
+2021-07-11,Space-time arithmetic quasi-periodic homogenization for damped wave equations,"This paper is concerned with space-time homogenization problems for damped
+wave equations with spatially periodic oscillating elliptic coefficients and
+temporally (arithmetic) quasi-periodic oscillating viscosity coefficients. Main
+results consist of a homogenization theorem, qualitative properties of
+homogenized matrices which appear in homogenized equations and a corrector
+result for gradients of solutions. In particular, homogenized equations and
+cell problems will turn out to deeply depend on the quasi-periodicity as well
+as the log ratio of spatial and temporal periods of the coefficients. Even
+types of equations will change depending on the log ratio and
+quasi-periodicity. Proofs of the main results are based on a (very weak)
+space-time two-scale convergence theory.",2107.04966v1
+2014-08-26,Stability of an abstract-wave equation with delay and a Kelvin-Voigt damping,"In this paper we consider a stabilization problem for the abstract-wave
+equation with delay. We prove an exponential stability result for appropriate
+damping coefficient. The proof of the main result is based on a
+frequency-domain approach.",1408.6261v2
+2015-10-14,The General Solution to Vlasov Equation and Linear Landau Damping,"A general solution to linearized Vlasov equation for an electron
+electrostatic wave in a homogeneous unmagnetized plasma is derived. The
+quasi-linear diffusion coefficient resulting from this solution is a continuous
+function of omega in contrast to that derived from the traditional Vlasov
+treatment. The general solution is also equivalent to the Landau treatment of
+the plasma normal oscillations, and hence leads to the well-known Landau
+damping.",1510.03949v1
+2017-08-24,Nonlinear network dynamics for interconnected micro-grids,"This paper deals with transient stability in interconnected micro-grids. The
+main contribution involves i) robust classification of transient dynamics for
+different intervals of the micro-grid parameters (synchronization, inertia, and
+damping); ii) exploration of the analogies with consensus dynamics and bounds
+on the damping coefficient separating underdamped and overdamped dynamics iii)
+the extension to the case of disturbed measurements due to hackering or
+parameter uncertainties.",1708.07296v1
+2020-09-16,Exponential decay for semilinear wave equations with viscoelastic damping and delay feedback,"In this paper we study a class of semilinear wave type equations with
+viscoelastic damping and delay feedback with time variable coefficient. By
+combining semigroup arguments, careful energy estimates and an iterative
+approach we are able to prove, under suitable assumptions, a well-posedness
+result and an exponential decay estimate for solutions corresponding to small
+initial data. This extends and concludes the analysis initiated in [16] and
+then developed in [13, 17].",2009.07777v1
+2022-12-04,Inverse problem of recovering the time-dependent damping and nonlinear terms for wave equations,"In this paper, we consider the inverse boundary problems of recovering the
+time-dependent nonlinearity and damping term for a semilinear wave equation on
+a Riemannian manifold. The Carleman estimate and the construction of Gaussian
+beams together with the higher order linearization are respectively used to
+derive the uniqueness results of recovering the coefficients.",2212.01815v2
+2022-10-08,Recover all Coefficients in Second-Order Hyperbolic Equations from Finite Sets of Boundary Measurements,"We consider the inverse hyperbolic problem of recovering all spatial
+dependent coefficients, which are the wave speed, the damping coefficient,
+potential coefficient and gradient coefficient, in a second-order hyperbolic
+equation defined on an open bounded domain with smooth enough boundary. We show
+that by appropriately selecting finite pairs of initial conditions we can
+uniquely and Lipschitz stably recover all those coefficients from the
+corresponding boundary measurements of their solutions. The proofs are based on
+sharp Carleman estimate, continuous observability inequality and regularity
+theory for general second-order hyperbolic equations.",2210.03865v1
+2002-04-25,Statics and Fast Dynamics of Nanomagnets with Vortex Structure,"Within the framework of the Landau-Lifshitz-Gilbert equation, using permalloy
+parameters, we study the statics and dynamics of flat circular magnetic
+nano-structures with an in-plane magnetic vortex configuration, putting
+particular emphasis on the (planar) vorticity of the magnetic state and on the
+(perpendicular) polarisation of the vortex center (which may be shifted with
+respect to the center of the circle). These binary degrees of freedom can in
+principle be used to manipulate two independent bits of information.
+  Studying switching processes induced by in-plane and out-of plane field
+pulses we find that it is possible to switch the vorticity of the magnetic dot
+on a time scale of 40 ps in strong enough and short enough perpendicular
+external field pulses (B_z^ext \approx 0.5 T, duration \approx 40 ps). But for
+realistically small values of the Gilbert damping, only the vorticity can be
+switched this fast, and it turns out that it is better to dismiss the center of
+the circle totally, concentrating on flat 'nano-rings' with an inner radius R_1
+and an outer radius R_2. On these 'nano-rings' the vortex state is more stable,
+and with respect to the switching of the vorticity these structures have
+similar properties as circular dots.",0204541v3
+2007-03-15,Functional Keldysh Theory of Spin Torques,"We present a microscopic treatment of current-induced torques and thermal
+fluctuations in itinerant ferromagnets based on a functional formulation of the
+Keldysh formalism. We find that the nonequilibrium magnetization dynamics is
+governed by a stochastic Landau-Lifschitz-Gilbert equation with spin transfer
+torques. We calculate the Gilbert damping parameter $\alpha$ and the
+non-adiabatic spin transfer torque parameter $\beta$ for a model ferromagnet.
+We find that $\beta \neq \alpha$, in agreement with the results obtained using
+imaginary-time methods of Kohno, Tatara and Shibata [J. Phys. Soc. Japan 75,
+113706 (2006)]. We comment on the relationship between $s-d$ and
+isotropic-Stoner toy models of ferromagnetism and more realistic
+density-functional-theory models, and on the implications of these
+relationships for predictions of the $\beta/\alpha$ ratio which plays a central
+role in domain wall motion. Only for a single-parabolic-band isotropic-Stoner
+model with an exchange splitting that is small compared to the Fermi energy
+does $\beta/\alpha$ approach one. In addition, our microscopic formalism
+incorporates naturally the fluctuations needed in a nonzero-temperature
+description of the magnetization. We find that to first order in the applied
+electric field, the usual form of thermal fluctuations via a phenomenological
+stochastic magnetic field holds.",0703414v2
+2010-10-04,Thermal fluctuation field for current-induced domain wall motion,"Current-induced domain wall motion in magnetic nanowires is affected by
+thermal fluctuation. In order to account for this effect, the
+Landau-Lifshitz-Gilbert equation includes a thermal fluctuation field and
+literature often utilizes the fluctuation-dissipation theorem to characterize
+statistical properties of the thermal fluctuation field. However, the theorem
+is not applicable to the system under finite current since it is not in
+equilibrium. To examine the effect of finite current on the thermal
+fluctuation, we adopt the influence functional formalism developed by Feynman
+and Vernon, which is known to be a useful tool to analyze effects of
+dissipation and thermal fluctuation. For this purpose, we construct a quantum
+mechanical effective Hamiltonian describing current-induced domain wall motion
+by generalizing the Caldeira-Leggett description of quantum dissipation. We
+find that even for the current-induced domain wall motion, the statistical
+properties of the thermal noise is still described by the
+fluctuation-dissipation theorem if the current density is sufficiently lower
+than the intrinsic critical current density and thus the domain wall tilting
+angle is sufficiently lower than pi/4. The relation between our result and a
+recent result, which also addresses the thermal fluctuation, is discussed. We
+also find interesting physical meanings of the Gilbert damping alpha and the
+nonadiabaticy parameter beta; while alpha characterizes the coupling strength
+between the magnetization dynamics (the domain wall motion in this paper) and
+the thermal reservoir (or environment), beta characterizes the coupling
+strength between the spin current and the thermal reservoir.",1010.0478v2
+2015-06-03,Antidamping spin-orbit torque driven by spin-flip reflection mechanism on the surface of a topological insulator: A time-dependent nonequilibrium Green function approach,"Motivated by recent experiments observing spin-orbit torque (SOT) acting on
+the magnetization $\vec{m}$ of a ferromagnetic (F) overlayer on the surface of
+a three-dimensional topological insulator (TI), we investigate the origin of
+the SOT and the magnetization dynamics in such systems. We predict that lateral
+F/TI bilayers of finite length, sandwiched between two normal metal leads, will
+generate a large antidamping-like SOT per very low charge current injected
+parallel to the interface. The large values of antidamping-like SOT are {\it
+spatially localized} around the transverse edges of the F overlayer. Our
+analysis is based on adiabatic expansion (to first order in $\partial
+\vec{m}/\partial t$) of time-dependent nonequilibrium Green functions (NEGFs),
+describing electrons pushed out of equilibrium both by the applied bias voltage
+and by the slow variation of a classical degree of freedom [such as
+$\vec{m}(t)$]. From it we extract formulas for spin torque and charge pumping,
+which show that they are reciprocal effects to each other, as well as Gilbert
+damping in the presence of SO coupling. The NEGF-based formula for SOT
+naturally splits into four components, determined by their behavior (even or
+odd) under the time and bias voltage reversal. Their complex angular dependence
+is delineated and employed within Landau-Lifshitz-Gilbert simulations of
+magnetization dynamics in order to demonstrate capability of the predicted SOT
+to efficiently switch $\vec{m}$ of a perpendicularly magnetized F overlayer.",1506.01303v3
+2015-07-11,"Realization of the thermal equilibrium in inhomogeneous magnetic systems by the Landau-Lifshitz-Gilbert equation with stochastic noise, and its dynamical aspects","It is crucially important to investigate effects of temperature on magnetic
+properties such as critical phenomena, nucleation, pinning, domain wall motion,
+coercivity, etc. The Landau-Lifshitz-Gilbert (LLG) equation has been applied
+extensively to study dynamics of magnetic properties. Approaches of Langevin
+noises have been developed to introduce the temperature effect into the LLG
+equation. To have the thermal equilibrium state (canonical distribution) as the
+steady state, the system parameters must satisfy some condition known as the
+fluctuation-dissipation relation. In inhomogeneous magnetic systems in which
+spin magnitudes are different at sites, the condition requires that the ratio
+between the amplitude of the random noise and the damping parameter depends on
+the magnitude of the magnetic moment at each site. Focused on inhomogeneous
+magnetic systems, we systematically showed agreement between the stationary
+state of the stochastic LLG equation and the corresponding equilibrium state
+obtained by Monte Carlo simulations in various magnetic systems including
+dipole-dipole interactions. We demonstrated how violations of the condition
+result in deviations from the true equilibrium state. We also studied the
+characteristic features of the dynamics depending on the choice of the
+parameter set. All the parameter sets satisfying the condition realize the same
+stationary state (equilibrium state). In contrast, different choices of
+parameter set cause seriously different relaxation processes. We show two
+relaxation types, i.e., magnetization reversals with uniform rotation and with
+nucleation.",1507.03075v1
+2017-01-12,Dynamic coupling of ferromagnets via spin Hall magnetoresistance,"The synchronized magnetization dynamics in ferromagnets on a nonmagnetic
+heavy metal caused by the spin Hall effect is investigated theoretically. The
+direct and inverse spin Hall effects near the ferromagnetic/nonmagnetic
+interface generate longitudinal and transverse electric currents. The
+phenomenon is known as the spin Hall magnetoresistance effect, whose magnitude
+depends on the magnetization direction in the ferromagnet due to the spin
+transfer effect. When another ferromagnet is placed onto the same nonmagnet,
+these currents are again converted to the spin current by the spin Hall effect
+and excite the spin torque to this additional ferromagnet, resulting in the
+excitation of the coupled motions of the magnetizations. The in-phase or
+antiphase synchronization of the magnetization oscillations, depending on the
+value of the Gilbert damping constant and the field-like torque strength, is
+found in the transverse geometry by solving the Landau-Lifshitz-Gilbert
+equation numerically. On the other hand, in addition to these synchronizations,
+the synchronization having a phase difference of a quarter of a period is also
+found in the longitudinal geometry. The analytical theory clarifying the
+relation among the current, frequency, and phase difference is also developed,
+where it is shown that the phase differences observed in the numerical
+simulations correspond to that giving the fixed points of the energy supplied
+by the coupling torque.",1701.03201v2
+2018-10-16,Superfluid spin transport in ferro- and antiferromagnets,"This paper focuses on spin superfluid transport, observation of which was
+recently reported in antiferromagnet Cr$_2$O$_3$ [Yuan et al., Sci. Adv. 4,
+eaat1098 (2018)]. This paper analyzes the role of dissipation in transformation
+of spin current injected with incoherent magnons to a superfluid spin current
+near the interface where spin is injected. The Gilbert damping parameter in the
+Landau-Lifshitz-Gilbert theory does not describe dissipation properly, and the
+dissipation parameters are calculated from the Boltzmann equation for magnons
+scattered by defects. The two-fluid theory is developed similar to the
+two-fluid theory for superfluids. This theory shows that the influence of
+temperature variation in bulk on the superfluid spin transport (bulk Seebeck
+effect) is weak at low temperatures. The scenario that the results of Yuan et
+al. are connected with the Seebeck effect at the interface between the spin
+detector and the sample is also discussed.
+  The Landau criterion for an antiferromagnet put in a magnetic field is
+derived from the spectrum of collective spin modes. The Landau instability
+starts in the gapped mode earlier than in the Goldstone gapless mode, in
+contrast to easy-plane ferromagnets where the Goldstone mode becomes unstable.
+The structure of the magnetic vortex in the geometry of the experiment is
+determined. The vortex core has the skyrmion structure with finite
+magnetization component normal to the magnetic field. This magnetization
+creates stray magnetic fields around the exit point of the vortex line from the
+sample, which can be used for experimental detection of vortices.",1810.07020v4
+2020-02-20,Stoner-Wohlfarth switching of the condensate magnetization in a dipolar spinor gas and the metrology of excitation damping,"We consider quasi-one-dimensional dipolar spinor Bose-Einstein condensates in
+the homogeneous-local-spin-orientation approximation, that is with
+unidirectional local magnetization. By analytically calculating the exact
+effective dipole-dipole interaction, we derive a Landau-Lifshitz-Gilbert
+equation for the dissipative condensate magnetization dynamics, and show how it
+leads to the Stoner-Wohlfarth model of a uni-axial ferro-magnetic particle,
+where the latter model determines the stable magnetization patterns and
+hysteresis curves for switching between them. For an external magnetic field
+pointing along the axial, long direction, we analytically solve the
+Landau-Lifshitz-Gilbert equation. The solution explicitly demonstrates that the
+magnetic dipole-dipole interaction {\it accelerates} the dissipative dynamics
+of the magnetic moment distribution and the associated dephasing of the
+magnetic moment direction. Under suitable conditions, dephasing of the
+magnetization direction due to dipole-dipole interactions occurs within time
+scales up to two orders of magnitude smaller than the lifetime of currently
+experimentally realized dipolar spinor condensates, e.g., produced with the
+large magnetic-dipole-moment atoms ${}^{166} \textrm{Er}$. This enables
+experimental access to the dissipation parameter $\Gamma$ in the
+Gross-Pitaevski\v\i~mean-field equation, for a system currently lacking a
+complete quantum kinetic treatment of dissipative processes and, in particular,
+an experimental check of the commonly used assumption that $\Gamma$ is a single
+scalar independent of spin indices.",2002.08723v2
+2022-06-20,First-principles calculation of the parameters used by atomistic magnetic simulations,"While the ground state of magnetic materials is in general well described on
+the basis of spin density functional theory (SDFT), the theoretical description
+of finite-temperature and non-equilibrium properties require an extension
+beyond the standard SDFT. Time-dependent SDFT (TD-SDFT), which give for example
+access to dynamical properties are computationally very demanding and can
+currently be hardly applied to complex solids. Here we focus on the alternative
+approach based on the combination of a parameterized phenomenological spin
+Hamiltonian and SDFT-based electronic structure calculations, giving access to
+the dynamical and finite-temperature properties for example via spin-dynamics
+simulations using the Landau-Lifshitz-Gilbert (LLG) equation or Monte Carlo
+simulations. We present an overview on the various methods to calculate the
+parameters of the various phenomenological Hamiltonians with an emphasis on the
+KKR Green function method as one of the most flexible band structure methods
+giving access to practically all relevant parameters. Concerning these, it is
+crucial to account for the spin-orbit coupling (SOC) by performing relativistic
+SDFT-based calculations as it plays a key role for magnetic anisotropy and
+chiral exchange interactions represented by the DMI parameters in the spin
+Hamiltonian. This concerns also the Gilbert damping parameters characterizing
+magnetization dissipation in the LLG equation, chiral multispin interaction
+parameters of the extended Heisenberg Hamiltonian, as well as spin-lattice
+interaction parameters describing the interplay of spin and lattice dynamics
+processes, for which an efficient computational scheme has been developed
+recently by the present authors.",2206.09969v1
+2023-09-25,Ultrafast Demagnetization through Femtosecond Generation of Non-thermal Magnons,"Ultrafast laser excitation of ferromagnetic metals gives rise to correlated,
+highly non-equilibrium dynamics of electrons, spins and lattice, which are,
+however, poorly described by the widely-used three-temperature model (3TM).
+Here, we develop a fully ab-initio parameterized out-of-equilibrium theory
+based on a quantum kinetic approach--termed (N+2) temperature model--that
+describes magnon occupation dynamics due to electron-magnon scattering. We
+apply this model to perform quantitative simulations on the ultrafast,
+laser-induced generation of magnons in iron and demonstrate that on these
+timescales the magnon distribution is non-thermal: predominantly high-energy
+magnons are created, while the magnon occupation close to the center of the
+Brillouin zone even decreases, due to a repopulation towards higher energy
+states via a so-far-overlooked scattering term. We demonstrate that the simple
+relation between magnetization and temperature computed at equilibrium does not
+hold in the ultrafast regime and that the 3TM greatly overestimates the
+demagnetization. The ensuing Gilbert damping becomes strongly magnon wavevector
+dependent and requires a description beyond the conventional
+Landau-Lifshitz-Gilbert spin dynamics. Our ab-initio-parameterized calculations
+show that ultrafast generation of non-thermal magnons provides a sizable
+demagnetization within 200fs in excellent comparison with experimentally
+observed laser-induced demagnetizations. Our investigation emphasizes the
+importance of non-thermal magnon excitations for the ultrafast demagnetization
+process.",2309.14167v3
+2023-12-12,Sliding Dynamics of Current-Driven Skyrmion Crystal and Helix in Chiral Magnets,"The skyrmion crystal (SkX) and helix (HL) phases, present in typical chiral
+magnets, can each be considered as forms of density waves but with distinct
+topologies. The SkX exhibits gyrodynamics analogous to electrons under a
+magnetic field, while the HL state resembles topological trivial spin density
+waves. However, unlike the charge density waves, the theoretical analysis of
+the sliding motion of SkX and HL remains unclear, especially regarding the
+similarities and differences in sliding dynamics between these two spin density
+waves. In this work, we systematically explore the sliding dynamics of SkX and
+HL in chiral magnets in the limit of large current density. We demonstrate that
+the sliding dynamics of both SkX and HL can be unified within the same
+theoretical framework as density waves, despite their distinct microscopic
+orders. Furthermore, we highlight the significant role of gyrotropic sliding
+induced by impurity effects in the SkX state, underscoring the impact of
+nontrivial topology on the sliding motion of density waves. Our theoretical
+analysis shows that the effect of impurity pinning is much stronger in HL
+compared with SkX, i.e., $\chi^{SkX}/\chi^{HL}\sim \alpha^2$ ($\chi^{SkX}$,
+$\chi^{HL}$: susceptibility to the impurity potential, $\alpha$ ($\ll 1$) is
+the Gilbert damping). Moreover, the velocity correction is mostly in the
+transverse direction to the current in SkX. These results are further
+substantiated by realistic Landau-Lifshitz-Gilbert simulations.",2312.07116v2
+2007-01-08,Coefficient of restitution for viscoelastic disks,"The dissipative collision of two identical viscoelastic disks is studied. By
+using a known law for the elastic part of the interaction force and the
+viscoelastic damping model an analytical solution for the coefficient of
+restitution shall be given. The coefficient of restitution depends
+significantly on the impact velocity. It approaches one for small velocities
+and decreases for increasing velocities.",0701142v1
+2008-02-29,Heat conduction and Fourier's law in a class of many particle dispersing billiards,"We consider the motion of many confined billiard balls in interaction and
+discuss their transport and chaotic properties. In spite of the absence of mass
+transport, due to confinement, energy transport can take place through binary
+collisions between neighbouring particles. We explore the conditions under
+which relaxation to local equilibrium occurs on time scales much shorter than
+that of binary collisions, which characterize the transport of energy, and
+subsequent relaxation to local thermal equilibrium. Starting from the
+pseudo-Liouville equation for the time evolution of phase-space distributions,
+we derive a master equation which governs the energy exchange between the
+system constituents. We thus obtain analytical results relating the transport
+coefficient of thermal conductivity to the frequency of collision events and
+compute these quantities. We also provide estimates of the Lyapunov exponents
+and Kolmogorov-Sinai entropy under the assumption of scale separation. The
+validity of our results is confirmed by extensive numerical studies.",0802.4455v3
+2014-07-01,Transport properties of Lévy walks: an analysis in terms of multistate processes,"Continuous time random walks combining diffusive and ballistic regimes are
+introduced to describe a class of L\'evy walks on lattices. By including
+exponentially-distributed waiting times separating the successive jump events
+of a walker, we are led to a description of such L\'evy walks in terms of
+multistate processes whose time-evolution is shown to obey a set of coupled
+delay differential equations. Using simple arguments, we obtain asymptotic
+solutions to these equations and rederive the scaling laws for the mean squared
+displacement of such processes. Our calculation includes the computation of all
+relevant transport coefficients in terms of the parameters of the models.",1407.0227v2
+2015-01-21,Lévy walks on lattices as multi-state processes,"Continuous-time random walks combining diffusive scattering and ballistic
+propagation on lattices model a class of L\'evy walks. The assumption that
+transitions in the scattering phase occur with exponentially-distributed
+waiting times leads to a description of the process in terms of multiple
+states, whose distributions evolve according to a set of delay differential
+equations, amenable to analytic treatment. We obtain an exact expression of the
+mean squared displacement associated with such processes and discuss the
+emergence of asymptotic scaling laws in regimes of diffusive and superdiffusive
+(subballistic) transport, emphasizing, in the latter case, the effect of
+initial conditions on the transport coefficients. Of particular interest is the
+case of rare ballistic propagation, in which case a regime of superdiffusion
+may lurk underneath one of normal diffusion.",1501.05216v1
+2015-01-31,Bases and Structure Constants of Generalized Splines with Integer Coefficients on Cycles,"An integer generalized spline is a set of vertex labels on an edge-labeled
+graph that satisfy the condition that if two vertices are joined by an edge,
+the vertex labels are congruent modulo the edge label. Foundational work on
+these objects comes from Gilbert, Polster, and Tymoczko, who generalize ideas
+from geometry/topology (equivariant cohomology rings) and algebra (algebraic
+splines) to develop the notion of generalized splines. Gilbert, Polster, and
+Tymoczko prove that the ring of splines on a graph can be decomposed in terms
+of splines on its subgraphs (in particular, on trees and cycles), and then
+fully analyze splines on trees. Following Handschy-Melnick-Reinders and Rose,
+we analyze splines on cycles, in our case integer generalized splines. The
+primary goal of this paper is to establish two new bases for the module of
+integer generalized splines on cycles: the triangulation basis and the King
+basis. Unlike bases in previous work, we are able to characterize each basis
+element completely in terms of the edge labels of the underlying cycle. As an
+application we explicitly construct the multiplication table for the ring of
+integer generalized splines in terms of the King basis.",1502.00176v1
+2019-05-31,Characterizing the mod-$\ell$ local Langlands correspondence by nilpotent gamma factors,"Let $F$ be a $p$-adic field and choose $k$ an algebraic closure of
+$\mathbb{F}_{\ell}$, with $\ell$ different from $p$. We define ``nilpotent
+lifts'' of irreducible generic $k$-representations of $GL_n(F)$, which take
+coefficients in Artin local $k$-algebras. We show that an irreducible generic
+$\ell$-modular representation $\pi$ of $GL_n(F)$ is uniquely determined by its
+collection of Rankin--Selberg gamma factors $\gamma(\pi\times
+\widetilde{\tau},X,\psi)$ as $\widetilde{\tau}$ varies over nilpotent lifts of
+irreducible generic $k$-representations $\tau$ of $GL_t(F)$ for $t=1,\dots,
+\lfloor \frac{n}{2}\rfloor$. This gives a characterization of the mod-$\ell$
+local Langlands correspondence in terms of gamma factors, assuming it can be
+extended to a surjective local Langlands correspondence on nilpotent lifts.",1905.13487v2
+2020-01-31,An efficient automated data analytics approach to large scale computational comparative linguistics,"This research project aimed to overcome the challenge of analysing human
+language relationships, facilitate the grouping of languages and formation of
+genealogical relationship between them by developing automated comparison
+techniques. Techniques were based on the phonetic representation of certain key
+words and concept. Example word sets included numbers 1-10 (curated), large
+database of numbers 1-10 and sheep counting numbers 1-10 (other sources),
+colours (curated), basic words (curated).
+  To enable comparison within the sets the measure of Edit distance was
+calculated based on Levenshtein distance metric. This metric between two
+strings is the minimum number of single-character edits, operations including:
+insertions, deletions or substitutions. To explore which words exhibit more or
+less variation, which words are more preserved and examine how languages could
+be grouped based on linguistic distances within sets, several data analytics
+techniques were involved. Those included density evaluation, hierarchical
+clustering, silhouette, mean, standard deviation and Bhattacharya coefficient
+calculations. These techniques lead to the development of a workflow which was
+later implemented by combining Unix shell scripts, a developed R package and
+SWI Prolog. This proved to be computationally efficient and permitted the fast
+exploration of large language sets and their analysis.",2001.11899v1
+2022-06-22,Homogenization of the Landau-Lifshitz-Gilbert equation with natural boundary condition,"The full Landau-Lifshitz-Gilbert equation with periodic material coefficients
+and natural boundary condition is employed to model the magnetization dynamics
+in composite ferromagnets. In this work, we establish the convergence between
+the homogenized solution and the original solution via a Lax equivalence
+theorem kind of argument. There are a few technical difficulties, including: 1)
+it is proven the classic choice of corrector to homogenization cannot provide
+the convergence result in the $H^1$ norm; 2) a boundary layer is induced due to
+the natural boundary condition; 3) the presence of stray field give rise to a
+multiscale potential problem. To keep the convergence rates near the boundary,
+we introduce the Neumann corrector with a high-order modification. Estimates on
+singular integral for disturbed functions and boundary layer are deduced, to
+conduct consistency analysis of stray field. Furthermore, inspired by length
+conservation of magnetization, we choose proper correctors in specific
+geometric space. These, together with a uniform $W^{1,6}$ estimate on original
+solution, provide the convergence rates in the $H^1$ sense.",2206.10948v1
+2023-10-13,Unified framework of the microscopic Landau-Lifshitz-Gilbert equation and its application to Skyrmion dynamics,"The Landau-Lifshitz-Gilbert (LLG) equation is widely used to describe
+magnetization dynamics. We develop a unified framework of the microscopic LLG
+equation based on the nonequilibrium Green's function formalism. We present a
+unified treatment for expressing the microscopic LLG equation in several
+limiting cases, including the adiabatic, inertial, and nonadiabatic limits with
+respect to the precession frequency for a magnetization with fixed magnitude,
+as well as the spatial adiabatic limit for the magnetization with slow
+variation in both its magnitude and direction. The coefficients of those terms
+in the microscopic LLG equation are explicitly expressed in terms of
+nonequilibrium Green's functions. As a concrete example, this microscopic
+theory is applied to simulate the dynamics of a magnetic Skyrmion driven by
+quantum parametric pumping. Our work provides a practical formalism of the
+microscopic LLG equation for exploring magnetization dynamics.",2310.08807v1
+2004-04-19,Nonlinear response of superparamagnets with finite damping: an analytical approach,"The strongly damping-dependent nonlinear dynamical response of classical
+superparamagnets is investigated by means of an analytical approach. Using
+rigorous balance equations for the spin occupation numbers a simple approximate
+expression is derived for the nonlinear susceptibility. The results are in good
+agreement with those obtained from the exact (continued-fraction) solution of
+the Fokker-Planck equation. The formula obtained could be of assistance in the
+modelling of the experimental data and the determination of the damping
+coefficient in superparamagnets.",0404445v1
+2005-05-10,Highly Damped Quasinormal Modes of Generic Single Horizon Black Holes,"We calculate analytically the highly damped quasinormal mode spectra of
+generic single-horizon black holes using the rigorous WKB techniques of
+Andersson and Howls\cite{Andersson}. We thereby provide a firm foundation for
+previous analysis, and point out some of their possible limitations. The
+numerical coefficient in the real part of the highly damped frequency is
+generically determined by the behavior of coupling of the perturbation to the
+gravitational field near the origin, as expressed in tortoise coordinates. This
+fact makes it difficult to understand how the famous $ln(3)$ could be related
+to the quantum gravitational microstates near the horizon.",0505044v1
+2003-09-15,Eigenfrequencies and expansions for damped wave equations,"We study eigenfrequencies and propagator expansions for damped wave equations
+on compact manifolds. Under the assumption of geometric control, the propagator
+is shown to admit an expansion in terms of finitely many eigenmodes near the
+real axis, with an error term exponentially decaying in time. In the presence
+of a nondegenerate elliptic closed geodesic not meeting the support of the
+damping coefficient, we show that there exists a sequence of eigenfrequencies
+converging rapidly to the real axis. In the case of Zoll manifolds, we show
+that the propagator can be expanded in terms of clusters of the
+eigenfrequencies in the entire spectral band.",0309250v1
+2010-03-08,A single-ion nonlinear mechanical oscillator,"We study the steady state motion of a single trapped ion oscillator driven to
+the nonlinear regime. Damping is achieved via Doppler laser-cooling. The ion
+motion is found to be well described by the Duffing oscillator model with an
+additional nonlinear damping term. We demonstrate a unique ability of tuning
+both the linear as well as the nonlinear damping coefficients by controlling
+the cooling laser parameters. Our observations open a way for the investigation
+of nonlinear dynamics on the quantum-to-classical interface as well as
+mechanical noise squeezing in laser-cooling dynamics.",1003.1577v1
+2012-02-24,Small data global existence for the semilinear wave equation with space-time dependent damping,"In this paper we consider the critical exponent problem for the semilinear
+wave equation with space-time dependent damping. When the damping is effective,
+it is expected that the critical exponent agrees with that of only space
+dependent coefficient case. We shall prove that there exists a unique global
+solution for small data if the power of nonlinearity is larger than the
+expected exponent. Moreover, we do not assume that the data are compactly
+supported. However, it is still open whether there exists a blow-up solution if
+the power of nonlinearity is smaller than the expected exponent.",1202.5379v1
+2012-03-21,Approximate rogue wave solutions of the forced and damped Nonlinear Schrödinger equation for water waves,"We consider the effect of the wind and the dissipation on the nonlinear
+stages of the modulational instability. By applying a suitable transformation,
+we map the forced/damped Nonlinear Schr\""odinger (NLS) equation into the
+standard NLS with constant coefficients. The transformation is valid as long as
+|{\Gamma}t| \ll 1, with {\Gamma} the growth/damping rate of the waves due to
+the wind/dissipation. Approximate rogue wave solutions of the equation are
+presented and discussed. The results shed some lights on the effects of wind
+and dissipation on the formation of rogue waves.",1203.4735v1
+2013-11-16,Shear viscosity due to the Landau damping from quark-pion interaction,"We have calculated the shear viscosity coefficient $\eta$ of the strongly
+interacting matter in the relaxation time approximation, where a quasi particle
+description of quarks with its dynamical mass is considered from NJL model. Due
+to the thermodynamic scattering of quarks with pseudo scalar type condensate
+(i.e. pion), a non zero Landau damping will be acquired by the propagating
+quarks. This Landau damping may be obtained from the Landau cut contribution of
+the in-medium self-energy of quark-pion loop, which is evaluated in the
+framework of real-time thermal field theory.",1311.4070v1
+2014-03-24,Existence Results for Some Damped Second-Order Volterra Integro-Differential Equations,"In this paper we make a subtle use of operator theory techniques and the
+well-known Schauder fixed-point principle to establish the existence of
+pseudo-almost automorphic solutions to some second-order damped
+integro-differential equations with pseudo-almost automorphic coefficients. In
+order to illustrate our main results, we will study the existence of
+pseudo-almost automorphic solutions to a structurally damped plate-like
+boundary value problem.",1403.5955v1
+2014-08-09,Local existence results for the Westervelt equation with nonlinear damping and Neumann as well as absorbing boundary conditions,"We investigate the Westervelt equation with several versions of nonlinear
+damping and lower order damping terms and Neumann as well as absorbing boundary
+conditions. We prove local in time existence of weak solutions under the
+assumption that the initial and boundary data are sufficiently small.
+Additionally, we prove local well-posedness in the case of spatially varying
+$L^{\infty}$ coefficients, a model relevant in high intensity focused
+ultrasound (HIFU) applications.",1408.2160v1
+2015-03-03,Large Deviations for the Langevin equation with strong damping,"We study large deviations in the Langevin dynamics, with damping of order
+$\e^{-1}$ and noise of order $1$, as $\e\downarrow 0$. The damping coefficient
+is assumed to be state dependent. We proceed first with a change of time and
+then, we use a weak convergence approach to large deviations and their
+equivalent formulation in terms of the Laplace principle, to determine the good
+action functional.
+  Some applications of these results to the exit problem from a domain and to
+the wave front propagation for a suitable class of reaction diffusion equations
+are considered.",1503.01027v1
+2017-06-15,Fractional Driven Damped Oscillator,"The resonances associated with a fractional damped oscillator which is driven
+by an oscillatory external force are studied. It is shown that such resonances
+can be manipulated by tuning up either the coefficient of the fractional
+damping or the order of the corresponding fractional derivatives.",1706.08596v1
+2017-09-13,Life-span of blowup solutions to semilinear wave equation with space-dependent critical damping,"This paper is concerned with the blowup phenomena for initial value problem
+of semilinear wave equation with critical space-dependent damping term
+(DW:$V$). The main result of the present paper is to give a solution of the
+problem and to provide a sharp estimate for lifespan for such a solution when
+$\frac{N}{N-1}<p\leq p_S(N+V_0)$, where $p_S(N)$ is the Strauss exponent for
+(DW:$0$). The main idea of the proof is due to the technique of test functions
+for (DW:$0$) originated by Zhou--Han (2014, MR3169791). Moreover, we find a new
+threshold value $V_0=\frac{(N-1)^2}{N+1}$ for the coefficient of critical and
+singular damping $|x|^{-1}$.",1709.04401v1
+2018-06-08,"Brownian motion of magnetic domain walls and skyrmions, and their diffusion constants","Extended numerical simulations enable to ascertain the diffusive behavior at
+finite temperatures of chiral walls and skyrmions in ultra-thin model Co layers
+exhibiting symmetric - Heisenberg - as well as antisymmetric -
+Dzyaloshinskii-Moriya - exchange interactions. The Brownian motion of walls and
+skyrmions is shown to obey markedly different diffusion laws as a function of
+the damping parameter. Topology related skyrmion diffusion suppression with
+vanishing damping parameter, albeit already documented, is shown to be
+restricted to ultra-small skyrmion sizes or, equivalently, to ultra-low damping
+coefficients, possibly hampering observation.",1806.03172v1
+2020-02-09,Fujita modified exponent for scale invariant damped semilinear wave equations,"The aim of this paper is to prove a blow up result of the solution for a
+semilinear scale invariant damped wave equation under a suitable decay
+condition on radial initial data. The admissible range for the power of the
+nonlinear term depends both on the damping coefficient and on the pointwise
+decay order of the initial data. In addition we give an upper bound estimate
+for the lifespan of the solution, in terms of the power of the nonlinearity,
+size and growth of initial data.",2002.03418v2
+2020-05-24,A transmission problem for the Timoshenko system with one local Kelvin-Voigt damping and non-smooth coefficient at the interface,"In this paper, we study the indirect stability of Timoshenko system with
+local or global Kelvin-Voigt damping, under fully Dirichlet or mixed boundary
+conditions. Unlike the results of H. L. Zhao, K. S. Liu, and C. G. Zhang and of
+X. Tian and Q. Zhang, in this paper, we consider the Timoshenko system with
+only one locally or globally distributed Kelvin-Voigt damping. Indeed, we prove
+that the energy of the system decays polynomially and that the obtained decay
+rate is in some sense optimal. The method is based on the frequency domain
+approach combining with multiplier method.",2005.12756v1
+2020-08-11,An inverse spectral problem for a damped wave operator,"This paper proposes a new and efficient numerical algorithm for recovering
+the damping coefficient from the spectrum of a damped wave operator, which is a
+classical Borg-Levinson inverse spectral problem. The algorithm is based on
+inverting a sequence of trace formulas, which are deduced by a recursive
+formula, bridging geometrical and spectrum information explicitly in terms of
+Fredholm integral equations. Numerical examples are presented to illustrate the
+efficiency of the proposed algorithm.",2008.04523v1
+2020-08-18,A class of Finite difference Methods for solving inhomogeneous damped wave equations,"In this paper, a class of finite difference numerical techniques is presented
+to solve the second-order linear inhomogeneous damped wave equation. The
+consistency, stability, and convergences of these numerical schemes are
+discussed. The results obtained are compared to the exact solution, ordinary
+explicit, implicit finite difference methods, and the fourth-order compact
+method (FOCM). The general idea of these methods is developed by using the
+C0-semigroups operator theory. We also showed that the stability region for the
+explicit finite difference scheme depends on the damping coefficient.",2008.08043v2
+2020-09-10,Blow-up results for semilinear damped wave equations in Einstein-de Sitter spacetime,"We prove by using an iteration argument some blow-up results for a semilinear
+damped wave equation in generalized Einstein-de Sitter spacetime with a
+time-dependent coefficient for the damping term and power nonlinearity. Then,
+we conjecture an expression for the critical exponent due to the main blow-up
+results, which is consistent with many special cases of the considered model
+and provides a natural generalization of Strauss exponent. In the critical
+case, we consider a non-autonomous and parameter-dependent Cauchy problem for a
+linear ODE of second-order, whose explicit solutions are determined by means of
+special functions' theory.",2009.05372v1
+2021-06-16,Sharp upper and lower bounds of the attractor dimension for 3D damped Euler-Bardina equations,"The dependence of the fractal dimension of global attractors for the damped
+3D Euler--Bardina equations on the regularization parameter $\alpha>0$ and
+Ekman damping coefficient $\gamma>0$ is studied. We present explicit upper
+bounds for this dimension for the case of the whole space, periodic boundary
+conditions, and the case of bounded domain with Dirichlet boundary conditions.
+The sharpness of these estimates when $\alpha\to0$ and $\gamma\to0$ (which
+corresponds in the limit to the classical Euler equations) is demonstrated on
+the 3D Kolmogorov flows on a torus.",2106.09077v1
+2022-03-12,Stability for nonlinear wave motions damped by time-dependent frictions,"We are concerned with the dynamical behavior of solutions to semilinear wave
+systems with time-varying damping and nonconvex force potential. Our result
+shows that the dynamical behavior of solution is asymptotically stable without
+any bifurcation and chaos. And it is a sharp condition on the damping
+coefficient for the solution to converge to some equilibrium. To illustrate our
+theoretical results, we provide some numerical simulations for dissipative
+sine-Gordon equation and dissipative Klein-Gordon equation.",2203.06312v1
+2022-06-07,"Decay property of solutions to the wave equation with space-dependent damping, absorbing nonlinearity, and polynomially decaying data","We study the large time behavior of solutions to the semilinear wave equation
+with space-dependent damping and absorbing nonlinearity in the whole space or
+exterior domains. Our result shows how the amplitude of the damping
+coefficient, the power of the nonlinearity, and the decay rate of the initial
+data at the spatial infinity determine the decay rates of the energy and the
+$L^2$-norm of the solution. In Appendix, we also give a survey of basic results
+on the local and global existence of solutions and the properties of weight
+functions used in the energy method.",2206.03218v2
+2022-12-18,Exponential decay of solutions of damped wave equations in one dimensional space in the $L^p$ framework for various boundary conditions,"We establish the decay of the solutions of the damped wave equations in one
+dimensional space for the Dirichlet, Neumann, and dynamic boundary conditions
+where the damping coefficient is a function of space and time. The analysis is
+based on the study of the corresponding hyperbolic systems associated with the
+Riemann invariants. The key ingredient in the study of these systems is the use
+of the internal dissipation energy to estimate the difference of solutions with
+their mean values in an average sense.",2212.09164v1
+2023-05-03,Lyapunov functions for linear damped wave equations in one-dimensional space with dynamic boundary conditions,"We establish the exponential decay of the solutions of the damped wave
+equations in one-dimensional space where the damping coefficient is a
+nowhere-vanishing function of space. The considered PDE is associated with
+several dynamic boundary conditions, also referred to as Wentzell/Ventzel
+boundary conditions in the literature. The analysis is based on the
+determination of appropriate Lyapunov functions and some further analysis. This
+result is associated with a regulation problem inspired by a real experiment
+with a proportional-integral control. Some numerical simulations and additional
+results on closed wave equations are also provided.",2305.01969v2
+2023-07-12,Asymptotic behavior of solutions to the Cauchy problem for 1-D p-system with space dependent damping,"We consider the Cauchy problem for one-dimensional p-system with damping of
+space-dependent coefficient. This system models the compressible flow through
+porous media in the Lagrangean coordinate. Our concern is an asymptotic
+behavior of solutions, which is expected to be the diffusion wave based on the
+Darcy law. To show this expectation, the problem is reformulated to the Cauchy
+problem for the second order quasilinear hyperbolic equation with space
+dependent damping, which is analyzed by the energy method.",2307.05865v1
+2023-07-12,Parabolic-elliptic Keller-Segel's system,"We study on the whole space R d the compressible Euler system with damping
+coupled to the Poisson equation when the damping coefficient tends towards
+infinity. We first prove a result of global existence for the Euler-Poisson
+system in the case where the damping is large enough, then, in a second step,
+we rigorously justify the passage to the limit to the parabolic-elliptic
+Keller-Segel after performing a diffusive rescaling, and get an explicit
+convergence rate. The overall study is carried out in 'critical' Besov spaces,
+in the spirit of the recent survey [16] by R. Danchin devoted to partially
+dissipative systems.",2307.05981v1
+2021-07-29,Microscopic analysis of sound attenuation in low-temperature amorphous solids reveals quantitative importance of non-affine effects,"Sound attenuation in low temperature amorphous solids originates from their
+disordered structure. However, its detailed mechanism is still being debated.
+Here we analyze sound attenuation starting directly from the microscopic
+equations of motion. We derive an exact expression for the zero-temperature
+sound damping coefficient. We verify that the sound damping coefficients
+calculated from our expression agree very well with results from independent
+simulations of sound attenuation. The small wavevector analysis of our
+expression shows that sound attenuation is primarily determined by the
+non-affine displacements' contribution to the sound wave propagation
+coefficient coming from the frequency shell of the sound wave. Our expression
+involves only quantities that pertain to solids' static configurations. It can
+be used to evaluate the low temperature sound damping coefficients without
+directly simulating sound attenuation.",2107.14254v2
+2023-10-29,Asymptotic profiles for the Cauchy problem of damped beam equation with two variable coefficients and derivative nonlinearity,"In this article we investigate the asymptotic profile of solutions for the
+Cauchy problem of the nonlinear damped beam equation with two variable
+coefficients: \[ \partial_t^2 u + b(t) \partial_t u - a(t) \partial_x^2 u +
+\partial_x^4 u
+  = \partial_x \left( N(\partial_x u) \right). \] In the authors' previous
+article [17], the asymptotic profile of solutions for linearized problem ($N
+\equiv 0$) was classified depending on the assumptions for the coefficients
+$a(t)$ and $b(t)$ and proved the asymptotic behavior in effective damping
+cases. We here give the conditions of the coefficients and the nonlinear term
+in order that the solution behaves as the solution for the heat equation: $b(t)
+\partial_t u - a(t) \partial_x^2 u=0$ asymptotically as $t \to \infty$.",2310.18878v1
+2023-08-14,Temperature Evolution of Magnon Propagation Length in Tm$_3$Fe$_5$O$_{12}$ Thin Films: Roles of Magnetic Anisotropy and Gilbert Damping,"The magnon propagation length ($\langle\xi\rangle$) of a ferro/ferrimagnet
+(FM) is one of the key factors that controls the generation and propagation of
+thermally-driven spin current in FM/heavy metal (HM) bilayer based
+spincaloritronic devices. Theory predicts that for the FM layer,
+$\langle\xi\rangle$ is inversely proportional to the Gilbert damping ($\alpha$)
+and the square root of the effective magnetic anisotropy constant ($K_{\rm
+eff}$). However, direct experimental evidence of this relationship is lacking.
+To experimentally confirm this prediction, we employ a combination of
+longitudinal spin Seebeck effect (LSSE), transverse susceptibility, and
+ferromagnetic resonance experiments to investigate the temperature evolution of
+$\langle\xi\rangle$ and establish its correlation with the effective magnetic
+anisotropy field, $H_K^{\rm eff}$ ($\propto K_{\rm eff}$) and $\alpha$ in
+Tm$_3$Fe$_5$O$_{12}$ (TmIG)/Pt bilayers. We observe concurrent drops in the
+LSSE voltage and $\langle\xi\rangle$ below 200$^\circ$K in TmIG/Pt bilayers
+regardless of TmIG film thickness and substrate choice and attribute it to the
+noticeable increases in $H_K^{\rm eff}$ and $\alpha$ that occur within the same
+temperature range. From the TmIG thickness dependence of the LSSE voltage, we
+determined the temperature dependence of $\langle\xi\rangle$ and highlighted
+its correlation with the temperature-dependent $H_K^{\rm eff}$ and $\alpha$ in
+TmIG/Pt bilayers, which will be beneficial for the development of rare-earth
+iron garnet-based efficient spincaloritronic nanodevices.",2308.07236v3
+2015-06-23,The remarkable effectiveness of time-dependent damping terms for second order evolution equations,"We consider a second order linear evolution equation with a dissipative term
+multiplied by a time-dependent coefficient. Our aim is to design the
+coefficient in such a way that all solutions decay in time as fast as possible.
+  We discover that constant coefficients do not achieve the goal, as well as
+time-dependent coefficients that are too big. On the contrary, pulsating
+coefficients which alternate big and small values in a suitable way prove to be
+more effective.
+  Our theory applies to ordinary differential equations, systems of ordinary
+differential equations, and partial differential equations of hyperbolic type.",1506.06915v1
+2018-04-20,A Weakly Nonlinear Model for the Damping of Resonantly Forced Density Waves in Dense Planetary Rings,"In this paper we address the stability of resonantly forced density waves in
+dense planetary rings.
+  Already by Goldreich & Tremaine (1978) it has been argued that density waves
+might be unstable, depending on the relationship between the ring's viscosity
+and the surface mass density.
+  In the recent paper Schmidt et al. (2016) we have pointed out that when -
+within a fluid description of the ring dynamics - the criterion for viscous
+overstability is satisfied, forced spiral density waves become unstable as
+well.
+  In this case, linear theory fails to describe the damping, but nonlinearity
+of the underlying equations guarantees a finite amplitude and eventually a
+damping of the wave.
+  We apply the multiple scale formalism to derive a weakly nonlinear damping
+relation from a hydrodynamical model.
+  This relation describes the resonant excitation and nonlinear viscous damping
+of spiral density waves in a vertically integrated fluid disk with density
+dependent transport coefficients.
+  The model consistently predicts density waves to be (linearly) unstable in a
+ring region where the conditions for viscous overstability are met.
+  Sufficiently far away from the Lindblad resonance, the surface mass density
+perturbation is predicted to saturate to a constant value due to nonlinear
+viscous damping.
+  The wave's damping lengths of the model depend on certain input parameters,
+such as the distance to the threshold for viscous overstability in parameter
+space and the ground state surface mass density.",1804.07674v1
+2006-02-17,Damped quantum harmonic oscillator,"In the framework of the Lindblad theory for open quantum systems the damping
+of the harmonic oscillator is studied. A generalization of the fundamental
+constraints on quantum mechanical diffusion coefficients which appear in the
+master equation for the damped quantum oscillator is presented; the
+Schr\""odinger and Heisenberg representations of the Lindblad equation are given
+explicitly. On the basis of these representations it is shown that various
+master equations for the damped quantum oscillator used in the literature are
+particular cases of the Lindblad equation and that the majority of these
+equations are not satisfying the constraints on quantum mechanical diffusion
+coefficients. Analytical expressions for the first two moments of coordinate
+and momentum are also obtained by using the characteristic function of the
+Lindblad master equation. The master equation is transformed into Fokker-Planck
+equations for quasiprobability distributions. A comparative study is made for
+the Glauber $P$ representation, the antinormal ordering $Q$ representation and
+the Wigner $W$ representation. It is proven that the variances for the damped
+harmonic oscillator found with these representations are the same. By solving
+the Fokker-Planck equations in the steady state, it is shown that the
+quasiprobability distributions are two-dimensional Gaussians with widths
+determined by the diffusion coefficients. The density matrix is represented via
+a generating function, which is obtained by solving a time-dependent linear
+partial differential equation derived from the master equation. Illustrative
+examples for specific initial conditions of the density matrix are provided.",0602149v1
+2006-05-25,Time Quantified Monte Carlo Algorithm for Interacting Spin Array Micromagnetic Dynamics,"In this paper, we reexamine the validity of using time quantified Monte Carlo
+(TQMC) method [Phys. Rev. Lett. 84, 163 (2000); Phys. Rev. Lett. 96, 067208
+(2006)] in simulating the stochastic dynamics of interacting magnetic
+nanoparticles. The Fokker-Planck coefficients corresponding to both TQMC and
+Langevin dynamical equation (Landau-Lifshitz-Gilbert, LLG) are derived and
+compared in the presence of interparticle interactions. The time quantification
+factor is obtained and justified. Numerical verification is shown by using TQMC
+and Langevin methods in analyzing spin-wave dispersion in a linear array of
+magnetic nanoparticles.",0605621v1
+2000-07-10,Fractal Dimensions of the Hydrodynamic Modes of Diffusion,"We consider the time-dependent statistical distributions of diffusive
+processes in relaxation to a stationary state for simple, two dimensional
+chaotic models based upon random walks on a line. We show that the cumulative
+functions of the hydrodynamic modes of diffusion form fractal curves in the
+complex plane, with a Hausdorff dimension larger than one. In the limit of
+vanishing wavenumber, we derive a simple expression of the diffusion
+coefficient in terms of this Hausdorff dimension and the positive Lyapunov
+exponent of the chaotic model.",0007008v1
+2000-10-06,The Fractality of the Hydrodynamic Modes of Diffusion,"Transport by normal diffusion can be decomposed into the so-called
+hydrodynamic modes which relax exponentially toward the equilibrium state. In
+chaotic systems with two degrees of freedom, the fine scale structure of these
+hydrodynamic modes is singular and fractal. We characterize them by their
+Hausdorff dimension which is given in terms of Ruelle's topological pressure.
+For long-wavelength modes, we derive a striking relation between the Hausdorff
+dimension, the diffusion coefficient, and the positive Lyapunov exponent of the
+system. This relation is tested numerically on two chaotic systems exhibiting
+diffusion, both periodic Lorentz gases, one with hard repulsive forces, the
+other with attractive, Yukawa forces. The agreement of the data with the theory
+is excellent.",0010017v1
+1998-05-29,Atom cooling and trapping by disorder,"We demonstrate the possibility of three-dimensional cooling of neutral atoms
+by illuminating them with two counterpropagating laser beams of mutually
+orthogonal linear polarization, where one of the lasers is a speckle field,
+i.e. a highly disordered but stationary coherent light field. This
+configuration gives rise to atom cooling in the transverse plane via a Sisyphus
+cooling mechanism similar to the one known in standard two-dimensional optical
+lattices formed by several plane laser waves. However, striking differences
+occur in the spatial diffusion coefficients as well as in local properties of
+the trapped atoms.",9805037v1
+2014-08-11,An optimal irrigation network with infinitely many branching points,"The Gilbert-Steiner problem is a mass transportation problem, where the cost
+of the transportation depends on the network used to move the mass and it is
+proportional to a certain power of the ""flow"". In this paper, we introduce a
+new formulation of the problem, which turns it into the minimization of a
+convex functional in a class of currents with coefficients in a group. This
+framework allows us to define calibrations, which can be used to prove the
+optimality of concrete configurations. We apply this technique to prove the
+optimality of a certain irrigation network, having the topological property
+mentioned in the title.",1408.2406v1
+2023-03-15,Algebraic Geometry codes in the sum-rank metric,"We introduce the first geometric construction of codes in the sum-rank
+metric, which we called linearized Algebraic Geometry codes, using quotients of
+the ring of Ore polynomials with coefficients in the function field of an
+algebraic curve. We study the parameters of these codes and give lower bounds
+for their dimension and minimum distance. Our codes exhibit quite good
+parameters, respecting a similar bound to Goppa's bound for Algebraic Geometry
+codes in the Hamming metric. Furthermore, our construction yields codes
+asymptotically better than the sum-rank version of the Gilbert-Varshamov bound.",2303.08903v2
+2023-05-31,Codes from Goppa codes,"On a Goppa code whose structure polynomial has coefficients in the symbol
+field, the Frobenius acts. Its fixed codewords form a subcode. Deleting the
+naturally occurred redundance, we obtain a new code. It is proved that these
+new codes approach the Gilbert-Varshamov bound. It is also proved that these
+codes can be decoded within $O(n^2(\logn)^a)$ operations in the symbol field,
+which is usually much small than the location field, where $n$ is the codeword
+length, and $a$ a constant determined by the polynomial factorization
+algorithm.",2305.19565v5
+2023-07-21,Thermomechanics of ferri-antiferromagnetic phase transition in finitely-strained rocks towards paleomagnetism,"The thermodynamic model of visco-elastic deformable magnetic materials at
+finite strains is formulated in a fully Eulerian way in rates with the aim to
+describe thermoremanent paleomagnetism in crustal rocks. The Landau theory
+applied to a ferro-to-para-magnetic phase transition, the gradient theory for
+magnetization (leading to exchange energy) with general mechanically dependent
+coefficient, hysteresis in magnetization evolution by Gilbert equation
+involving objective corotational time derivative of magnetization, and
+demagnetizing field are considered in the model. The Jeffreys viscoelastic
+rheology is used with temperature-dependent creep to model solidification or
+melting transition. The model complies with energy conservation and the
+Clausius-Duhem entropy inequality.",2307.11826v2
+2011-06-23,Ratchet effect on a relativistic particle driven by external forces,"We study the ratchet effect of a damped relativistic particle driven by both
+asymmetric temporal bi-harmonic and time-periodic piecewise constant forces.
+This system can be formally solved for any external force, providing the
+ratchet velocity as a non-linear functional of the driving force. This allows
+us to explicitly illustrate the functional Taylor expansion formalism recently
+proposed for this kind of systems. The Taylor expansion reveals particularly
+useful to obtain the shape of the current when the force is periodic, piecewise
+constant. We also illustrate the somewhat counterintuitive effect that
+introducing damping may induce a ratchet effect. When the force is symmetric
+under time-reversal and the system is undamped, under symmetry principles no
+ratchet effect is possible. In this situation increasing damping generates a
+ratchet current which, upon increasing the damping coefficient eventually
+reaches a maximum and decreases toward zero. We argue that this effect is not
+specific of this example and should appear in any ratchet system with tunable
+damping driven by a time-reversible external force.",1106.4861v1
+2011-07-17,Nonlinear-damping continuation of the nonlinear Schrödinger equation - a numerical study,"We study the nonlinear-damping continuation of singular solutions of the
+critical and supercritical NLS. Our simulations suggest that for generic
+initial conditions that lead to collapse in the undamped NLS, the solution of
+the weakly-damped NLS $$
+i\psi_t(t,\X)+\Delta\psi+|\psi|^{p-1}\psi+i\delta|\psi|^{q-1}\psi=0,\qquad0<\delta
+\ll 1, $$ is highly asymmetric with respect to the singularity time, and the
+post-collapse defocusing velocity of the singular core goes to infinity as the
+damping coefficient $\delta$ goes to zero. In the special case of the
+minimal-power blowup solutions of the critical NLS, the continuation is a
+minimal-power solution with a higher (but finite) defocusing velocity, whose
+magnitude increases monotonically with the nonlinear damping exponent $q$.",1107.3281v1
+2018-04-06,Exponential Integrators Preserving Local Conservation Laws of PDEs with Time-Dependent Damping/Driving Forces,"Structure-preserving algorithms for solving conservative PDEs with added
+linear dissipation are generalized to systems with time-dependent
+damping/driving terms. This study is motivated by several PDE models of
+physical phenomena, such as Korteweg-de Vries, Klein-Gordon, Schr\""{o}dinger,
+and Camassa-Holm equations, all with damping/driving terms and time-dependent
+coefficients. Since key features of the PDEs under consideration are described
+by local conservation laws, which are independent of the boundary conditions,
+the proposed (second-order in time) discretizations are developed with the
+intent of preserving those local conservation laws. The methods are
+respectively applied to a damped-driven nonlinear Schr\""{o}dinger equation and
+a damped Camassa-Holm equation. Numerical experiments illustrate the
+structure-preserving properties of the methods, as well as favorable results
+over other competitive schemes.",1804.02266v1
+2019-11-13,Dipole oscillations of fermionic superfluids along the BEC-BCS crossover in disordered potentials,"We investigate dipole oscillations of ultracold Fermi gases along the BEC-BCS
+crossover through disordered potentials. We observe a disorder-induced damping
+of oscillations as well as a change of the fundamental Kohn-mode frequency. The
+measurement results are compared to numerical density matrix renormalization
+group calculations as well as to a three-dimensional simulation of
+non-interacting fermions. Experimentally, we find a disorder-dependent damping,
+which grows approximately with the second power of the disorder strength.
+Moreover, we observe experimentally a change of oscillation frequency which
+deviates from the expected behavior of a damped harmonic oscillator on a
+percent level. While this behavior is qualitatively expected from the
+theoretical models used, quantitatively the experimental observations show a
+significantly stronger effect than predicted by theory. Furthermore, while the
+frequency shift seems to scale differently with interaction strength in the BEC
+versus BCS regime, the damping coefficient apparently decreases with the
+strength of interaction, but not with the sign, which changes for BEC and BCS
+type Fermi gases. This is surprising, as the dominant damping mechanisms are
+expected to be different in the two regimes.",1911.05638v1
+2020-05-16,Simultaneous observation of anti-damping and inverse spin Hall effect in La$_{0.67}$Sr$_{0.33}$MnO$_{3}$/Pt bilayer system,"Manganites have shown potential in spintronics because they exhibit high spin
+polarization. Here, by ferromagnetic resonance we have studied the damping
+properties of La$_{0.67}$Sr$_{0.33}$MnO$_{3}$/Pt bilayers which are prepared by
+oxide molecular beam epitaxy. The damping coefficient ($\alpha$) of
+La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ (LSMO) single layer is found to be 0.0104.
+However the LSMO/Pt bilayers exhibit decrease in $\alpha$ with increase in Pt
+thickness. This decrease in the value of $\alpha$ is probably due to high
+anti-damping like torque. Further, we have investigated the angle dependent
+inverse spin Hall effect (ISHE) to quantify the spin pumping voltage from other
+spin rectification effects such as anomalous Hall effect and anisotropic
+magnetoresistance. We have observed high spin pumping voltage ($\sim$~20 $ \mu
+V$). The results indicate that both anti-damping and spin pumping phenomena are
+occuring simultaneously.",2005.07848v3
+2021-10-26,Theory of sound attenuation in amorphous solids from nonaffine motions,"We present a theoretical derivation of acoustic phonon damping in amorphous
+solids based on the nonaffine response formalism for the viscoelasticity of
+amorphous solids. The analytical theory takes into account the nonaffine
+displacements in transverse waves and is able to predict both the ubiquitous
+low-energy diffusive damping $\sim k^{2}$, as well as a novel contribution to
+the Rayleigh damping $\sim k^{4}$ at higher wavevectors and the crossover
+between the two regimes observed experimentally. The coefficient of the
+diffusive term is proportional to the microscopic viscous (Langevin-type)
+damping in particle motion (which arises from anharmonicity), and to the
+nonaffine correction to the static shear modulus, whereas the Rayleigh damping
+emerges in the limit of low anharmonicity, consistent with previous
+observations and macroscopic models. Importantly, the $k^4$ Rayleigh
+contribution derived here does not arise from harmonic disorder or elastic
+heterogeneity effects and it is the dominant mechanism for sound attenuation in
+amorphous solids as recently suggested by molecular simulations.",2110.13446v2
+2022-03-10,Accelerated gradient methods combining Tikhonov regularization with geometric damping driven by the Hessian,"In a Hilbert setting, for convex differentiable optimization, we consider
+accelerated gradient dynamics combining Tikhonov regularization with
+Hessian-driven damping. The Tikhonov regularization parameter is assumed to
+tend to zero as time tends to infinity, which preserves equilibria. The
+presence of the Tikhonov regularization term induces a strong convexity
+property which vanishes asymptotically. To take advantage of the exponential
+convergence rates attached to the heavy ball method in the strongly convex
+case, we consider the inertial dynamic where the viscous damping coefficient is
+taken proportional to the square root of the Tikhonov regularization parameter,
+and therefore also converges towards zero. Moreover, the dynamic involves a
+geometric damping which is driven by the Hessian of the function to be
+minimized, which induces a significant attenuation of the oscillations. Under
+an appropriate tuning of the parameters, based on Lyapunov's analysis, we show
+that the trajectories have at the same time several remarkable properties: they
+provide fast convergence of values, fast convergence of gradients towards zero,
+and strong convergence to the minimum norm minimizer. This study extends a
+previous paper by the authors where similar issues were examined but without
+the presence of Hessian driven damping.",2203.05457v2
+2022-08-25,The Effect of Frequency Droop Damping on System Parameters and Battery Sizing During Load Change Condition,"Inverter-based resources (IBR) have been widely studied for their advantages
+on the current power systems. This increase in the penetration of renewable
+energy has raised some concerns about the stability of the existing grid.
+Historically, power systems are dominated by synchronous generators that can
+easily react to system instability due to high inertia and damping
+characteristics. However, with IBR, the control of the inverter plays a crucial
+role in contributing to the system stability and enhancing the functionality of
+the inverters. One of these novel control methods is droop control. Droop
+characteristics are used to control voltage, frequency, and active and reactive
+power. This paper presents the impact of frequency droop damping on system
+frequency, real power, and the rate of change of frequency with distributed
+energy resources. Also, battery sizing is suggested based on the results. The
+results also show the need for optimal selection for the frequency droop
+damping to fulfill the appropriate battery size in terms of cost and
+performance. The simulations are carried out in an electromagnetic transient
+program (EMTP)",2208.12291v1
+2023-07-28,Premature jump-down mimicks nonlinear damping in nanoresonators,"Recent experiments on nano-resonators in a bistable regime use the
+`jump-down' point between states to infer mechanical properties of the membrane
+or a load, but often suggest the presence of some nonlinear damping. Motivated
+by such experiments, we develop a mechanical model of a membrane subject to a
+uniform, oscillatory load and linear damping. We solve this model numerically
+and compare its jump-down behaviour with standard asymptotic predictions for a
+one-dimensional Duffing oscillator with strain stiffening. We show that the
+axisymmetric, but spatially-varying, problem can be mapped to the Duffing
+problem with coefficients determined rationally from the model's Partial
+Differential Equations. However, we also show that jump-down happens earlier
+than expected (i.e.~at lower frequency, and with a smaller oscillation
+amplitude). Although this premature jump-down is often interpreted as the
+signature of a nonlinear damping in experiments, its appearance in numerical
+simulations with only linear damping suggests instead that indicate that the
+limitations of asymptotic results may, at least sometimes, be the cause. We
+therefore suggest that care should be exercised in interpreting the results of
+nano-resonator experiments.",2307.15656v1
+2023-10-11,Damping Density of an Absorptive Shoebox Room Derived from the Image-Source Method,"The image-source method is widely applied to compute room impulse responses
+(RIRs) of shoebox rooms with arbitrary absorption. However, with increasing RIR
+lengths, the number of image sources grows rapidly, leading to slow
+computation. In this paper, we derive a closed-form expression for the damping
+density, which characterizes the overall multi-slope energy decay. The
+omnidirectional energy decay over time is directly derived from the damping
+density. The resulting energy decay model accurately matches the late
+reverberation simulated via the image-source method. The proposed model allows
+the fast stochastic synthesis of late reverberation by shaping noise with the
+energy envelope. Simulations of various wall damping coefficients demonstrate
+the model's accuracy. The proposed model consistently outperforms the energy
+decay prediction accuracy compared to a state-of-the-art approximation method.
+The paper elaborates on the proposed damping density's applicability to
+modeling multi-sloped sound energy decay, predicting reverberation time in
+non-diffuse sound fields, and fast frequency-dependent RIR synthesis.",2310.07363v1
+2003-11-17,Cosmic Ray Scattering by Compressible Magnetohydrodynamic Turbulence,"Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call
+for substantial revisions in the picture of cosmic ray transport. In this paper
+we use recently obtained scaling laws for MHD modes to calculate the scattering
+frequency for cosmic rays in the ISM. We consider gyroresonance with MHD modes
+(Alfvenic, slow and fast) and transit-time damping (TTD) by fast modes. We
+provide calculations of cosmic ray scattering for various phases of
+interstellar medium with realistic interstellar turbulence driving that is
+consistent with the velocity dispersions observed in diffuse gas. We account
+for the turbulence cutoff arising from both collisional and collisionless
+damping. We obtain analytical expressions for diffusion coefficients that enter
+Fokker-Planck equation describing cosmic ray evolution. We calculate the
+scattering rate and parallel spatial diffusion coefficients of cosmic rays for
+both Alfvenic and fast modes. We conclude that fast modes provides the dominant
+contribution to cosmic ray scattering for the typical interstellar conditions
+in spite of the fact that fast modes are subjected to damping. We show that the
+efficiency of the scattering depends on the plasma beta since it determines the
+damping of the fast modes. We also show that the streaming instability is
+modified in the presence of turbulence.",0311369v1
+2010-03-16,Justification of the symmetric damping model of the dynamical Casimir effect in a cavity with a semiconductor mirror,"A ""microscopic"" justification of the ""symmetric damping"" model of a quantum
+oscillator with time-dependent frequency and time-dependent damping is given.
+This model is used to predict results of experiments on simulating the
+dynamical Casimir effect in a cavity with a photo-excited semiconductor mirror.
+It is shown that the most general bilinear time-dependent coupling of a
+selected oscillator (field mode) to a bath of harmonic oscillators results in
+two equal friction coefficients for the both quadratures, provided all the
+coupling coefficients are proportional to a single arbitrary function of time
+whose duration is much shorter than the periods of all oscillators. The choice
+of coupling in the rotating wave approximation form leads to the ""mimimum
+noise"" model of the quantum damped oscillator, introduced earlier in a pure
+phenomenological way.",1003.3061v2
+2022-07-13,Energy decay for the time dependent damped wave equation,"Energy decay is established for the damped wave equation on compact
+Riemannian manifolds where the damping coefficient is allowed to depend on
+time. Using a time dependent observability inequality, it is shown that the
+energy of solutions decays at an exponential rate if the damping coefficient
+satisfies a time dependent analogue of the classical geometric control
+condition. Existing time dependent observability inequalities are improved by
+removing technical assumptions on the permitted initial data.",2207.06260v4
+2022-10-10,Finite time extinction for a critically damped Schr{ö}dinger equation with a sublinear nonlinearity,"This paper completes some previous studies by several authors on the finite
+time extinction for nonlinear Schr{\""o}dinger equation when the nonlinear
+damping term corresponds to the limit cases of some ``saturating non-Kerr law''
+$F(|u|^2)u=\frac{a}{\varepsilon+(|u|^2)^\alpha}u,$ with $a\in\mathbb{C},$
+$\varepsilon\geqslant0,$ $2\alpha=(1-m)$ and $m\in[0,1).$ Here we consider the
+sublinear case $0<m<1$ with a critical damped coefficient: $a\in\mathbb{C}$ is
+assumed to be in the set $D(m)=\big\{z\in\mathbb{C}; \; \mathrm{Im}(z)>0 \text{
+and } 2\sqrt{m}\mathrm{Im}(z)=(1-m)\mathrm{Re}(z)\big\}.$ Among other things,
+we know that this damping coefficient is critical, for instance, in order to
+obtain the monotonicity of the associated operator (see the paper by Liskevich
+and Perel'muter [16] and the more recent study by Cialdea and Maz'ya [14]). The
+finite time extinction of solutions is proved by a suitable energy method after
+obtaining appropiate a priori estimates. Most of the results apply to
+non-necessarily bounded spatial domains.",2210.04493v4
+2023-12-28,Cause-effect relationship between model parameters and damping performance of hydraulic shock absorbers,"Despite long-term research and development of modern shock absorbers, the
+effect of variations of several crucial material and model parameters still
+remains dubious. The goal of this work is therefore a study of the changes of
+shock absorber dynamics with respect to typical parameter ranges in a realistic
+model. We study the impact of shim properties, as well as geometric features
+such as discharge coefficients and bleed orifice cross section. We derive
+cause-effect relationships by nonlinear parameter fitting of the differential
+equations of the model and show digressive and progressive quadratic damping
+curves for shim number and thickness, sharp exponential curves for discharge
+coefficients, and leakage width, as well as a linear decrease of damping
+properties with bleed orifice area. Temperature increase affecting material
+properties, such as density and viscosity of the mineral oil, is found to have
+a mostly linear relationship with damping and pressure losses. Our results are
+not only significant for the general understanding of shock absorber dynamics,
+but also serve as a guidance for the development of specific models by
+following the proposed methodology.",2312.17175v1
+2024-01-04,A Pure Integral-Type PLL with a Damping Branch to Enhance the Stability of Grid-Tied Inverter under Weak Grids,"In a phase-locked loop (PLL) synchronized inverter, due to the strong
+nonlinear coupling between the PLL's parame-ters and the operation power angle,
+the equivalent damping coefficient will quickly deteriorate while the power
+angle is close to 90{\deg} under an ultra-weak grid, which causes the
+synchronous instability. To address this issue, in this letter, a pure
+integral-type phase-locked loop (IPLL) with a damping branch is proposed to
+replace the traditional PI-type PLL. The equivalent damping coefficient of an
+IPLL-synchronized inverter is decoupled with the steady-state power angle. As a
+result, the IPLL-synchronized inverter can stably operate under an ultra-weak
+grid when the equilibrium point exists. Finally, time-domain simulation results
+verify the effectiveness and correctness of the proposed IPLL.",2401.02202v1
+2024-01-16,Waves in strong centrifugal filed: dissipative gas,"In the fast rotating gas (with the velocity typical for Iguassu gas
+centrifuge) three families of linear waves exist with different polarizations
+and law of dispersion. The energy of the waves is basically concentrated at the
+axis of rotation in the rarefied region. Therefore these waves decay on the
+distance comparable with the wavelength. There is only one type of waves
+propagating strictly along the axis of rotation with the law of dispersion
+similar to ordinary acoustic waves. These waves are interested for the physics
+of gas centrifuges. The energy density of these waves concentrates at the wall
+of the rotor. These waves have weak damping due to the molecular viscosity and
+heat conductivity. The damping coefficient is determined for this type of waves
+by numerical calculations. Analytical approximations for the damping
+coefficient is defined as well. At the parameters typical for the Iguassu
+centrifuge the damping is defined by interaction of the waves with the rotor
+wall.",2401.08240v1
+2024-01-19,Upper bound of the lifespan of the solution to the nonlinear fractional wave equations with time-dependent damping,"In this paper, we study the Cauchy problem of the nonlinear wave equation
+with fractional Laplacian and time-dependent damping. Firstly, we derive the
+weighted Sobolev estimate of the solution operators for the linear wave
+equation with the damping of constant coefficient, and prove the local
+existence and uniqueness in the weighted Sobolev space for the power-type
+nonlinearity and $b(t)\in L^\infty$, by the contraction mapping principle.
+Secondly, we consider the case of the source nonlinearity $f(u)\approx |u|^p$.
+In the subcritical and critical cases $1<p\leq p_c=1+\frac \sigma N$, based on
+the blow-up result on the ordinary differential inequality, we could prove the
+blow-up of the solution and obtain the upper bound of the lifespan. And the
+upper bound of the lifespan in the critical case is independent on the
+coefficient of the time-dependent damping and is completely new even if the
+classical case $b(t)=1$.",2401.10552v1
+2014-01-08,Dynamic exchange via spin currents in acoustic and optical modes of ferromagnetic resonance in spin-valve structures,"Two ferromagnetic layers magnetically decoupled by a thick normal metal
+spacer layer can be, nevertheless, dynamically coupled via spin currents
+emitted by the spin-pump and absorbed through the spin-torque effects at the
+neighboring interfaces. A decrease of damping in both layers due to a partial
+compensation of the angular momentum leakage in each layer was previously
+observed at the coincidence of the two ferromagnetic resonances. In case of
+non-zero magnetic coupling, such a dynamic exchange will depend on the mutual
+precession of the magnetic moments in the layers. A difference in the linewidth
+of the resonance peaks is expected for the acoustic and optical regimes of
+precession. However, the interlayer coupling hybridizes the resonance responses
+of the layers and therefore can also change their linewidths. The interplay
+between the two mechanisms has never been considered before. In the present
+work, the joint influence of the hybridization and non-local damping on the
+linewidth has been studied in weakly coupled NiFe/CoFe/Cu/CoFe/MnIr spin-valve
+multilayers. It has been found that the dynamic exchange by spin currents is
+different in the optical and acoustic modes, and this difference is dependent
+on the interlayer coupling strength. In contrast to the acoustic precession
+mode, the dynamic exchange in the optical mode works as an additional damping
+source. A simulation in the framework of the Landau-Lifshitz-Gilbert formalism
+for two ferromagnetic layers coupled magnetically and by spin currents has been
+done to separate the effects of the non-local damping from the resonance modes
+hybridization. In our samples both mechanisms bring about linewidth changes of
+the same order of magnitude, but lead to a distinctly different angular
+behavior. The obtained results are relevant for a broad class of coupled
+magnetic multilayers with ballistic regime of the spin transport.",1401.1672v1
+2020-08-29,Exploring a quantum-information-relevant magnonic material: Ultralow damping at low temperature in the organic ferrimagnet V[TCNE]x,"Quantum information science and engineering requires novel low-loss magnetic
+materials for magnon-based quantum-coherent operations. The search for low-loss
+magnetic materials, traditionally driven by applications in microwave
+electronics near room-temperature, has gained additional constraints from the
+need to operate at cryogenic temperatures for many applications in quantum
+information science and technology. Whereas yttrium iron garnet (YIG) has been
+the material of choice for decades, the emergence of molecule-based materials
+with robust magnetism and ultra-low damping has opened new avenues for
+exploration. Specifically, thin-films of vanadium tetracyanoethylene (V[TCNE]x)
+can be patterned into the multiple, connected structures needed for hybrid
+quantum elements and have shown room-temperature Gilbert damping ({\alpha} = 4
+\times 10^-5) that rivals the intrinsic (bulk) damping otherwise seen only in
+highly-polished YIG spheres (far more challenging to integrate into arrays).
+Here, we present a comprehensive and systematic study of the low-temperature
+magnetization dynamics for V[TCNE]x thin films, with implications for their
+application in quantum systems. These studies reveal a temperature-driven,
+strain-dependent magnetic anisotropy that compensates the thin-film shape
+anisotropy, and the recovery of a magnetic resonance linewidth at 5 K that is
+comparable to room-temperature values (roughly 2 G at 9.4 GHz). We can account
+for these variations of the V[TCNE]x linewidth within the context of scattering
+from very dilute paramagnetic impurities, and anticipate additional linewidth
+narrowing as the temperature is further reduced.",2008.13061v3
+2011-09-08,On the attenuation coefficient of monomode periodic waveguides,"It is widely accepted that, on ensemble average, the transmission T of guided
+modes decays exponentially with the waveguide length L due to small
+imperfections, leading to the important figure of merit defined as the
+attenuation-rate coefficient alpha = -<ln(T)>/L. In this letter, we evidence
+that the exponential-damping law is not valid in general for periodic monomode
+waveguides, especially as the group velocity decreases. This result that
+contradicts common beliefs and experimental practices aiming at measuring alpha
+is supported by a theoretical study of light transport in the limit of very
+small imperfections, and by numerical results obtained for two waveguide
+geometries that offer contrasted damping behaviours.",1109.1642v1
+2011-12-31,Stability of cnoidal waves in the parametrically driven nonlinear Schrödinger equation,"The parametrically driven, damped nonlinear Schr\""odinger equation has two
+cn- and two dn-wave solutions. We show that one pair of the cn and dn solutions
+is unstable for any combination of the driver's strength, dissipation
+coefficient and spatial period of the wave; this instability is against
+periodic perturbations. The second dn-wave solution is shown to be unstable
+against antiperiodic perturbations --- in a certain region of the parameter
+space. We also consider quasiperiodic perturbations with long modulation
+wavelength, in the limit where the driving strength is only weakly exceeding
+the damping coefficient.",1201.0263v1
+2016-04-20,Reconstruction for multiwave imaging in attenuating media with large damping coefficient,"In this article we study the reconstruction problem in TAT/PAT on an
+attenuating media. Namely, we prove a reconstruction procedure of the initial
+condition for the damped wave equation via Neumann series that works for
+arbitrary large smooth attenuation coefficients extending the result of Homan
+in [1]. We also illustrate the theoretical result by including some numerical
+experiments at the end of the paper.",1604.06068v3
+2016-09-20,H{ö}lder stability in determining the potential and the damping coefficient in a wave equation,"We improve the preceding results obtained by the first and the second authors
+in [3]. They concern the stability issue of the inverse problem that consists
+in determining the potential and the damping coefficient in a wave equation
+from an initial-to-boundary operator. We partially modify the arguments in [3]
+to show that actually we have H{\""o}lder stability instead of logarithmic
+stability.",1609.06102v1
+2021-11-30,Determining damping terms in fractional wave equations,"This paper deals with the inverse problem of recovering an arbitrary number
+of fractional damping terms in a wave equation. We develop several approaches
+on uniqueness and reconstruction, some of them relying on Tauberian theorems on
+the relation between the asymptotics of solutions in time and Laplace domain.
+Also the possibility of additionally recovering space dependent coefficients or
+initial data is discussed. The resulting methods for reconstructing
+coefficients and fractional orders in these terms are tested numerically.
+Additionally, we provide an analysis of the forward problem, a multiterm
+fractional wave equation.",2112.00080v2
+2023-06-28,Global solutions and blow-up for the wave equation with variable coefficients: II. boundary supercritical source,"In this paper, we consider the wave equation with variable coefficients and
+boundary damping and supercritical source terms. The goal of this work is
+devoted to prove the local and global existence, and classify decay rate of
+energy depending on the growth near zero on the damping term. Moreover, we
+prove the blow-up of the weak solution with positive initial energy as well as
+nonpositive initial energy.",2306.15897v4
+2023-07-29,An inverse problem for the fractionally damped wave equation,"We consider an inverse problem for a Westervelt type nonlinear wave equation
+with fractional damping. This equation arises in nonlinear acoustic imaging,
+and we show the forward problem is locally well-posed. We prove that the smooth
+coefficient of the nonlinearity can be uniquely determined, based on the
+knowledge of the source-to-solution map and a priori knowledge of the
+coefficient in an arbitrarily small subset of the domain. Our approach relies
+on a second order linearization as well as the unique continuation property of
+the spectral fractional Laplacian.",2307.16065v1
+2011-11-09,Stabilization by switching control methods,"In this paper we consider some stabilization problems for the wave equation
+with switching. We prove exponential stability results for appropriate damping
+coefficients. The proof of the main results is based on D'Alembert formula and
+some energy estimates.",1111.2171v1
+2015-03-31,Existence of the global attractor for the plate equation with nonlocal nonlinearity in R^{n},"We consider Cauchy problem for the semilinear plate equation with nonlocal
+nonlinearity. Under mild conditions on the damping coefficient, we prove that
+the semigroup generated by this problem possesses a global attractor.",1503.09123v1
+2021-03-29,Nonequilibrium Dynamics of the Chiral Quark Condensate under a Strong Magnetic Field,"Strong magnetic fields impact quantum-chromodynamics (QCD) properties in
+several situations; examples include the early universe, magnetars, and
+heavy-ion collisions. These examples share a common trait: time evolution. A
+prominent QCD property impacted by a strong magnetic field is the quark
+condensate, an approximate order parameter of the QCD transition between a
+high-temperature quark-gluon phase and a low-temperature hadronic phase. We use
+the linear sigma model with quarks to address the quark condensate time
+evolution under a strong magnetic field. We use the closed time path formalism
+of nonequilibrium quantum field theory to integrate out the quarks and obtain a
+mean-field Langevin equation for the condensate. The Langevin equation features
+dissipation and noise kernels controlled by a damping coefficient. We compute
+the damping coefficient for magnetic field and temperature values achieved in
+peripheral relativistic heavy-ion collisions and solve the Langevin equation
+for a temperature quench scenario. The magnetic field changes the dissipation
+and noise pattern by increasing the damping coefficient compared to the
+zero-field case. An increased damping coefficient increases fluctuations and
+time scales controlling condensate's short-time evolution, a feature that can
+impact hadron formation at the QCD transition. The formalism developed here can
+be extended to include other order parameters, hydrodynamic modes, and system's
+expansion to address magnetic field effects in complex settings as heavy-ion
+collisions, the early universe, and magnetars.",2103.15665v1
+2003-04-18,Elementary Excitations of Ferromagnetic Metal Nanoparticles,"We present a theory of the elementary spin excitations in transition metal
+ferromagnet nanoparticles which achieves a unified and consistent quantum
+description of both collective and quasiparticle physics. The theory starts by
+recognizing the essential role played by spin-orbit interactions in determining
+the energies of ferromagnetic resonances in the collective excitation spectrum
+and the strength of their coupling to low-energy particle-hole excitations. We
+argue that a crossover between Landau-damped ferromagnetic resonance and
+pure-state collective magnetic excitations occurs as the number of atoms in
+typical transition metal ferromagnet nanoparticles drops below approximately
+$10^4$, approximately where the single-particle level spacing, $\delta$,
+becomes larger than, $\sqrt{\alpha} E_{\rm res}$, where $E_{\rm res}$ is the
+ferromagnetic resonance frequency and $\alpha$ is the Gilbert damping
+parameter. We illustrate our ideas by studying the properties of semi-realistic
+model Hamiltonians, which we solve numerically for nanoparticles containing
+several hundred atoms. For small nanoparticles, we find one isolated
+ferromagnetic resonance collective mode below the lowest particle-hole
+excitation energy, at $E_{\rm res} \approx 0.1$ meV. The spectral weight of
+this pure excitation nearly exhausts the transverse dynamical susceptibility
+spectral weight. As $\delta$ approaches $\sqrt{\alpha} E_{\rm res}$, the
+ferromagnetic collective excitation is more likely to couple strongly with
+discrete particle-hole excitations. In this regime the distinction between the
+two types of excitations blurs. We discuss the significance of this picture for
+the interpretation of recent single-electron tunneling experiments.",0304427v1
+2014-08-02,Tunnel magnetoresistance and spin-transfer-torque switching in polycrystalline Co2FeAl full-Heusler alloy magnetic tunnel junctions on Si/SiO2 amorphous substrates,"We studied polycrystalline B2-type Co2FeAl (CFA) full-Heusler alloy based
+magnetic tunnel junctions (MTJs) fabricated on a Si/SiO2 amorphous substrate.
+Polycrystalline CFA films with a (001) orientation, a high B2 ordering, and a
+flat surface were achieved using a MgO buffer layer. A tunnel magnetoresistance
+(TMR) ratio up to 175% was obtained for an MTJ with a CFA/MgO/CoFe structure on
+a 7.5-nm-thick MgO buffer. Spin-transfer torque induced magnetization switching
+was achieved in the MTJs with a 2-nm-thick polycrystalline CFA film as a
+switching layer. Using a thermal activation model, the intrinsic critical
+current density (Jc0) was determined to be 8.2 x 10^6 A/cm^2, which is lower
+than 2.9 x 10^7 A/cm^2, the value for epitaxial CFA-MTJs [Appl. Phys. Lett.
+100, 182403 (2012)]. We found that the Gilbert damping constant evaluated using
+ferromagnetic resonance measurements for the polycrystalline CFA film was
+~0.015 and was almost independent of the CFA thickness (2~18 nm). The low Jc0
+for the polycrystalline MTJ was mainly attributed to the low damping of the CFA
+layer compared with the value in the epitaxial one (~0.04).",1408.0341v1
+2018-02-20,Ultrafast magnetization dynamics in pure and doped Heusler and inverse Heusler alloys,"By using a multiscale approach based on first-principles density functional
+theory combined with atomistic spin dynamics, we investigate the electronic
+structure and magnetization dynamics of an inverse Heusler and a Heusler
+compound and their alloys, i. e. Mn$_{2-x}Z_x$CoAl and Mn$_{2-x}Z_x$VAl, where
+$Z$ = Mo, W, Os and Ru, respectively. A signature of the ferrimagnetic ordering
+of Mn$_{2}$CoAl and Mn$_{2}$VAl Heusler alloys is reflected in the calculated
+Heisenberg exchange constants. They decay very rapidly with the interatomic
+distance and have short range, which is a consequence of the existence of the
+finite gap in the minority spin band. The calculated Gilbert damping parameter
+of both Mn$_2$CoAl and Mn$_2$VAl is high compared to other half-metals, but
+interestingly in the particular case of the inverse Mn$_{2}$CoAl alloys and due
+to the spin-gapless semiconducting property, the damping parameters decrease
+with the doping concentration in clear contradiction to the general trend.
+Atomistic spin dynamics simulations predict ultrafast magnetisation switching
+in Mn$_{2}$CoAl and Mn$_{2}$VAl under the influence of an external magnetic
+field, starting from a threshold field of $2\text{T}$. Our overall finding
+extends with Heusler and inverse Heusler alloys, the class of materials that
+exhibits laser induced magnetic switching.",1802.07195v1
+2018-04-10,GONG Catalog of Solar Filament Oscillations Near Solar Maximum,"We have catalogued 196 filament oscillations from the GONG $H{\alpha}$
+network data during several months near the maximum of solar cycle 24 (January
+- June 2014). Selected examples from the catalog are described in detail, along
+with our statistical analyses of all events. Oscillations were classified
+according to their velocity amplitude: 106 small-amplitude oscillations (SAOs),
+with velocities $<10\mathrm{\, km \; s^{-1}}$, and 90 large-amplitude
+oscillations (LAOs), with velocities $>10\mathrm{\, km \; s^{-1}}$. Both SAOs
+and LAOs are common, with one event of each class every two days on the visible
+side of the Sun. For nearly half of the events we identified their apparent
+trigger. The period distribution has a mean value of 58$\pm$15 min for both
+types of oscillations. The distribution of the damping time per period peaks at
+$\tau/P=1.75$ and $1.25$ for SAOs and LAOs respectively. We confirmed that LAO
+damping rates depend nonlinearly on the oscillation velocity. The angle between
+the direction of motion and the filament spine has a distribution centered at
+$27^\circ$ for all filament types. This angle agrees with the observed
+direction of filament-channel magnetic fields, indicating that most of the
+catalogued events are longitudinal (i.e., undergo field-aligned motions). We
+applied seismology to determine the average radius of curvature in the magnetic
+dips, $R\approx89$ Mm, and the average minimum magnetic-field strength,
+$B\approx16$ G. The catalog is available to the community online, and is
+intended to be expanded to cover at least 1 solar cycle.",1804.03743v1
+2018-10-16,Spin-wave-induced lateral temperature gradient in a YIG thin film/GGG system excited in an ESR cavity,"Lateral thermal gradient of an yttrium iron garnet (YIG) film under the
+microwave application in the cavity of the electron spin resonance system (ESR)
+was measured at room temperature by fabricating a Cu/Sb thermocouple onto it.
+To date, thermal transport in YIG films caused by the Damon-Eshbach mode (DEM)
+- the unidirectional spin-wave heat conveyer effect - was demonstrated only by
+the excitation using coplanar waveguides. Here we show that effect exists even
+under YIG excitation using the ESR cavity - tool often employed to realize spin
+pumping. The temperature difference observed around the ferromagnetic resonance
+(FMR) field under the 4 mW microwave power peaked at 13 mK. The observed
+thermoelectric signal indicates the imbalance of the population between the
+DEMs that propagate near the top and bottom surfaces of the YIG film. We
+attribute the DEM population imbalance to the different magnetic damping near
+the top and bottom YIG surfaces. Additionally, the spin wave dynamics of the
+system were investigated using the micromagnetic simulations. The micromagnetic
+simulations confirmed the existence of the DEM imbalance in the system with the
+increased Gilbert damping at one of the YIG interfaces. The reported results
+are indispensable for the quantitative estimation of the electromotive force in
+the spin-charge conversion experiments using ESR cavities.",1810.06875v1
+2021-08-24,Shape anisotropy effect on magnetization reversal induced by linear down chirp pulse,"We investigate the influence of shape anisotropy on the magnetization
+reversal of a single-domain magnetic nanoparticle driven by a circularly
+polarized linear down-chirp microwave field pulse (DCMP). Based on the
+Landau-Lifshitz-Gilbert equation, numerical results show that the three
+controlling parameters of DCMP, namely, microwave amplitude, initial frequency
+and chirp rate, decrease with the increase of shape anisotropy. For certain
+shape anisotropy, the reversal time significantly reduces. These findings are
+related to the competition of shape anisotropy and uniaxial magnetocrystalline
+anisotropy and thus to the height of energy barrier which separates the two
+stable states. The result of damping dependence of magnetization reversal
+indicates that for a certain sample shape, there exists an optimal damping
+situation at which magnetization is fastest. Moreover, it is also shown that
+the required microwave field amplitude can be lowered by applying the
+spin-polarized current simultaneously. The usage of an optimum combination of
+both microwave field pulse and current is suggested to achieve cost efficiency
+and faster switching. So these findings may provide the knowledge to fabricate
+the shape of a single domain nanoparticle for the fast and power-efficient
+magnetic data storage device.",2108.10965v2
+2021-11-23,Resonant dynamics of skyrmion lattices in thin film multilayers: Localised modes and spin wave emission,"The spectral signatures of magnetic skyrmions under microwave field
+excitation are of fundamental interest and can be an asset for high frequency
+applications. These topological solitons can be tailored in multilayered thin
+films, but the experimental observation of their spin wave dynamics remains
+elusive, in particular due to large damping. Here, we study Pt/FeCoB/AlO$_x$
+multilayers hosting dense and robust skyrmion lattices at room temperature with
+Gilbert damping of $\sim 0.02$. We use magnetic force microscopy to
+characterise their static magnetic phases and broadband ferromagnetic resonance
+to probe their high frequency response. Micromagnetic simulations reproduce the
+experiments with accuracy and allow us to identify distinct resonant modes
+detected in the skyrmion lattice phase. Low ($<$ 2 GHz) and intermediate
+frequency ($2-8$ GHz) modes involve excitations localised to skyrmion edges in
+conjunction with precession of the uniform background magnetisation, while a
+high frequency ($>$ 12 GHz) mode corresponds to in-phase skyrmion core
+precession emitting spin waves into uniform background with wavelengths in the
+50--80 nm range commensurate with the lattice structure. These findings could
+be instrumental in the investigation of room temperature wave scattering and
+the implementation of novel microwave processing schemes in reconfigurable
+arrays of solitons.",2111.11797v2
+2022-05-20,Effects of Crystalline Disorder on Interfacial and Magnetic Properties of Sputtered Topological Insulator/Ferromagnet Heterostructures,"Thin films of Topological insulators (TIs) coupled with ferromagnets (FMs)
+are excellent candidates for energy-efficient spintronics devices. Here, the
+effect of crystalline structural disorder of TI on interfacial and magnetic
+properties of sputter-deposited TI/FM, Bi2Te3/Ni80Fe20, heterostructures is
+reported. Ni and a smaller amount of Fe from Py was found to diffuse across the
+interface and react with Bi2Te3. For highly crystalline c-axis oriented Bi2Te3
+films, a giant enhancement in Gilbert damping is observed, accompanied by an
+effective out-of-plane magnetic anisotropy and enhanced damping-like spin-orbit
+torque (DL-SOT), possibly due to the topological surface states (TSS) of
+Bi2Te3. Furthermore, a spontaneous exchange bias is observed in hysteresis loop
+measurements at low temperatures. This is because of an antiferromagnetic
+topological interfacial layer formed by reaction of the diffused Ni with Bi2Te3
+which couples with the FM, Ni80Fe20. For increasing disorder of Bi2Te3, a
+significant weakening of exchange interaction in the AFM interfacial layer is
+found. These experimental results Abstract length is one paragraph.",2205.09913v1
+2022-12-24,Anatomy of ultrafast quantitative magneto-acoustics in freestanding nickel thin films,"We revisit the quantitative analysis of the ultrafast magneto-acoustic
+experiment in a freestanding nickel thin film by Kim and Bigot [1] by applying
+our recently proposed approach of magnetic and acoustic eigenmodes
+decomposition by Vernik et al. [2]. We show that the application of our
+modeling to the analysis of time-resolved reflectivity measurements allows for
+the determination of amplitudes and lifetimes of standing perpendicular
+acoustic phonon resonances with unprecedented accuracy. The acoustic damping is
+found to scale as $\propto\omega^2$ for frequencies up to 80~GHz and the peak
+amplitudes reach $10^{-3}$. The experimentally measured magnetization dynamics
+for different orientations of an external magnetic field agrees well with
+numerical solutions of magneto-elastically driven magnon harmonic oscillators.
+Symmetry-based selection rules for magnon-phonon interactions predicted by our
+modeling approach allow for the unambiguous discrimination between spatially
+uniform and non-uniform modes, as confirmed by comparing the resonantly
+enhanced magneto-elastic dynamics simultaneously measured on opposite sides of
+the film. Moreover, the separation of time scales for (early) rising and (late)
+decreasing precession amplitudes provide access to magnetic (Gilbert) and
+acoustic damping parameters in a single measurement.",2212.12673v1
+2023-05-16,Non-Hermitian Casimir Effect of Magnons,"There has been a growing interest in non-Hermitian quantum mechanics. The key
+concepts of quantum mechanics are quantum fluctuations. Quantum fluctuations of
+quantum fields confined in a finite-size system induce the zero-point energy
+shift. This quantum phenomenon, the Casimir effect, is one of the most striking
+phenomena of quantum mechanics in the sense that there are no classical analogs
+and has been attracting much attention beyond the hierarchy of energy scales,
+ranging from elementary particle physics to condensed matter physics, together
+with photonics. However, the non-Hermitian extension of the Casimir effect and
+the application to spintronics have not yet been investigated enough, although
+exploring energy sources and developing energy-efficient nanodevices are its
+central issues. Here we fill this gap. By developing a magnonic analog of the
+Casimir effect into non-Hermitian systems, we show that this non-Hermitian
+Casimir effect of magnons is enhanced as the Gilbert damping constant (i.e.,
+the energy dissipation rate) increases. When the damping constant exceeds a
+critical value, the non-Hermitian Casimir effect of magnons exhibits an
+oscillating behavior, including a beating one, as a function of the film
+thickness and is characterized by the exceptional point. Our result suggests
+that energy dissipation serves as a key ingredient of Casimir engineering.",2305.09231v1
+2008-02-21,Gas Damping Coefficient Research for MEMS Comb Linear Vibration Gyroscope,"Silicon-MEMS gyroscope is an important part of MEMS (Micro Electrical
+Mechanical System). There are some disturb ignored in traditional gyroscope
+that must be evaluated newly because of its smaller size (reach the level of
+micron). In these disturb, the air pressure largely influences the performance
+of MEMS gyroscope. Different air pressure causes different gas damping
+coefficient for the MEMS comb linear vibration gyroscope and different gas
+damping coefficient influences the quality factor of the gyroscope directive.
+The quality factor influences the dynamic working bandwidth of the MEMS comb
+linear vibration gyroscope, so it is influences the output characteristic of
+the MEMS comb linear vibration gyroscope. The paper shows the relationship
+between the air pressure and the output amplified and phase of the detecting
+axis through analyzing the air pressure influence on the MEMS comb linear
+vibration gyroscope. It discusses the influence on the frequency distribute and
+quality factor of the MEMS comb linear vibration gyroscope for different air
+pressure.",0802.3048v1
+2008-11-13,Higher order energy decay rates for damped wave equations with variable coefficients,"Under appropriate assumptions the energy of wave equations with damping and
+variable coefficients $c(x)u_{tt}-\hbox{div}(b(x)\nabla u)+a(x)u_t =h(x)$ has
+been shown to decay. Determining the rate of decay for the higher order
+energies involving the $k$th order spatial and time derivatives has been an
+open problem with the exception of some sparse results obtained for $k=1,2,3$.
+We establish estimates that optimally relate the higher order energies with the
+first order energy by carefully analyzing the effects of linear damping. The
+results concern weighted (in time) and also pointwise (in time) energy decay
+estimates. We also obtain $L^\infty$ estimates for the solution $u$. As an
+application we compute explicit decay rates for all energies which involve the
+dimension $n$ and the bounds for the coefficients $a(x)$ and $b(x)$ in the case
+$c (x)=1$ and $h(x)=0.$",0811.2159v1
+2009-05-13,Time-dependent barrier passage of Two-dimensional non-Ohmic damping system,"The time-dependent barrier passage of an anomalous damping system is studied
+via the generalized Langevin equation (GLE) with non-Ohmic memory damping
+friction tensor and corresponding thermal colored noise tensor describing a
+particle passing over the saddle point of a two-dimensional quadratic potential
+energy surface. The time-dependent passing probability and transmission
+coefficient are analytically obtained by using of the reactive flux method. The
+long memory aspect of friction is revealed to originate a non-monotonic
+$\delta$(power exponent of the friction) dependence of the passing probability,
+the optimal incident angle of the particle and the steady anomalous
+transmission coefficient. In the long time limit a bigger steady transmission
+coefficient is obtained which means less barrier recrossing than the
+one-dimensional case.",0905.2074v1
+2011-07-11,One-dimensional vertical dust strings in a glass box,"The oscillation spectrum of a one-dimensional vertical dust string formed
+inside a glass box on top of the lower electrode in a GEC reference cell was
+studied. A mechanism for creating a single vertical dust string is described.
+It is shown that the oscillation amplitudes, resonance frequencies, damping
+coefficients, and oscillation phases of the dust particles separate into two
+distinct groups. One group exhibits low damping coefficients, increasing
+amplitudes and decreasing resonance frequencies for dust particles closer to
+the lower electrode. The other group shows high damping coefficients but
+anomalous resonance frequencies and amplitudes. At low oscillation frequencies,
+the two groups are also separated by a {\pi}-phase difference. One possible
+cause for the difference in behavior between the two groups is discussed.",1107.2074v1
+2016-02-24,Pressure of a gas of underdamped active dumbbells,"The pressure exerted on a wall by a gas at equilibrium does not depend on the
+shape of the confining potential defining the wall. In contrast, it has been
+shown recently [A.P. Solon et al., Nat. Phys. 11, 673 (2015)] that a gas of
+overdamped active particles exerts on a wall a force that depends on the
+confining potential, resulting in a net force on an asymmetric wall between two
+chambers at equal densities. Here, considering a model of underdamped
+self-propelled dumbbells in two dimensions, we study how the behavior of the
+pressure depends on the damping coefficient of the dumbbells, thus exploring
+inertial effects. We find in particular that the force exerted on a moving wall
+between two chambers at equal density continuously vanishes at low damping
+coefficient, and exhibits a complex dependence on the damping coefficient at
+low density, when collisions are scarce. We further show that this behavior of
+the pressure can to a significant extent be understood in terms of the
+trajectories of individual particles close to and in contact with the wall.",1602.07420v1
+2016-03-31,Recovery of time-dependent damping coefficients and potentials appearing in wave equations from partial data,"We consider the inverse problem of determining a time-dependent damping
+coefficient $a$ and a time-dependent potential $q$, appearing in the wave
+equation $\partial_t^2u-\Delta_x u+a(t,x)\partial_tu+q(t,x)u=0$ in
+$Q=(0,T)\times\Omega$, with $T>0$ and $\Omega$ a $ \mathcal C^2$ bounded domain
+of $\mathbb R^n$, $n\geq2$, from partial observations of the solutions on
+$\partial Q$. More precisely, we look for observations on $\partial Q$ that
+allow to determine uniquely a large class of time-dependent damping
+coefficients $a$ and time-dependent potentials $q$ without involving an
+important set of data. We prove global unique determination of $a\in
+W^{1,p}(Q)$, with $p>n+1$, and $q\in L^\infty(Q)$ from partial observations on
+$\partial Q$.",1603.09600v2
+2020-05-04,Remarks on asymptotic order for the linear wave equation with the scale-invariant damping and mass with $L^r$-data,"In the present paper, we consider the linear wave equation with the
+scale-invariant damping and mass. It is known that the global behavior of the
+solution depends on the size of the coefficients in front of the damping and
+mass at initial time $t=0$. Indeed, the solution satisfies the similar decay
+estimate to that of the corresponding heat equation if it is large and to that
+of the modified wave equation if it is small. In our previous paper, we obtain
+the scattering result and its asymptotic order for the data in the energy space
+$H^1\times L^2$ when the coefficients are in the wave regime. In fact, the
+threshold of the coefficients relies on the spatial decay of the initial data.
+Namely, it varies depending on $r$ when the initial data is in $L^r$ ($1\leq r
+< 2$). In the present paper, we will show the scattering result and the
+asymptotic order in the wave regime for $L^r$-data, which is wider than the
+wave regime for the data in the energy space. Moreover, we give an improvement
+of the asymptotic order obtained in our previous paper for the data in the
+energy space.",2005.01335v2
+2023-06-18,Partial data inverse problem for hyperbolic equation with time-dependent damping coefficient and potential,"We study an inverse problem of determining a time-dependent damping
+coefficient and potential appearing in the wave equation in a compact
+Riemannian manifold of dimension three or higher. More specifically, we are
+concerned with the case of conformally transversally anisotropic manifolds, or
+in other words, compact Riemannian manifolds with boundary conformally embedded
+in a product of the Euclidean line and a transversal manifold. With an
+additional assumption of the attenuated geodesic ray transform being injective
+on the transversal manifold, we prove that the knowledge of a certain partial
+Cauchy data set determines time-dependent damping coefficient and potential
+uniquely.",2306.10442v2
+2013-03-14,Drag and Diffusion coefficients in extreme scenarios of temperature and chemical potential,"A comparative study of high and zero temperature plasma for the case of
+damping rate, drag and diffusion coefficients have been presented. In each of
+these quantities, it is revealed how the magnetic interaction dominates over
+the electric one at zero temperature unlike what happens at high temperature.",1303.3353v1
+2002-09-07,Neural network analysis of the magnetization reversal in magnetic dot arrays,"We simulated the remagnetization dynamics of the ultra-dense and ultra-thin
+magnetic dot array system with dipole-dipole and exchange coupling
+interactions. Within the proposed 2D XY superlattice model, the square dots are
+modeled by the spatially modulated exchange-couplings. The dipole-dipole
+interactions were approximated by the hierarchical sums and dynamics was
+reduced to damping term of the Landau-Lifshitz-Gilbert equation. The simulation
+of 40 000 spin system leads to nonequilibrium nonuniform configurations with
+soliton-antisoliton pairs detected at intra-dot and inter-dot scales. The
+classification of intra-dot magnetic configurations was performed using the
+self-adaptive neural networks with varying number of neurons.",0209186v1
+2005-04-06,Macrospin Models of Spin Transfer Dynamics,"The current-induced magnetization dynamics of a spin valve are studied using
+a macrospin (single domain) approximation and numerical solutions of a
+generalized Landau-Lifshitz-Gilbert equation. For the purpose of quantitative
+comparison with experiment [Kiselev {\it et al.} Nature {\bf 425}, 380 (2003)],
+we calculate the resistance and microwave power as a function of current and
+external field including the effects of anisotropies, damping, spin-transfer
+torque, thermal fluctuations, spin-pumping, and incomplete absorption of
+transverse spin current. While many features of experiment appear in the
+simulations, there are two significant discrepancies: the current dependence of
+the precession frequency and the presence/absence of a microwave quiet magnetic
+phase with a distinct magnetoresistance signature. Comparison is made with
+micromagnetic simulations designed to model the same experiment.",0504142v1
+2006-02-01,Mapping Monte Carlo to Langevin dynamics: A Fokker-Planck approach,"We propose a general method of using the Fokker-Planck equation (FPE) to link
+the Monte-Carlo (MC) and the Langevin micromagnetic schemes. We derive the
+drift and disusion FPE terms corresponding to the MC method and show that it is
+analytically equivalent to the stochastic Landau-Lifshitz-Gilbert (LLG)
+equation of Langevin-based micromagnetics. Subsequent results such as the time
+quantification factor for the Metropolis MC method can be rigorously derived
+from this mapping equivalence. The validity of the mapping is shown by the
+close numerical convergence between the MC method and the LLG equation for the
+case of a single magnetic particle as well as interacting arrays of particles.
+We also found that our Metropolis MC is accurate for a large range of damping
+factors $\alpha$, unlike previous time-quantified MC methods which break down
+at low $\alpha$, where precessional motion dominates.",0602011v2
+2006-04-21,Dynamic approach for micromagnetics close to the Curie temperature,"In conventional micromagnetism magnetic domain configurations are calculated
+based on a continuum theory for the magnetization which is assumed to be of
+constant length in time and space. Dynamics is usually described with the
+Landau-Lifshitz-Gilbert (LLG) equation the stochastic variant of which includes
+finite temperatures. Using simulation techniques with atomistic resolution we
+show that this conventional micromagnetic approach fails for higher
+temperatures since we find two effects which cannot be described in terms of
+the LLG equation: i) an enhanced damping when approaching the Curie temperature
+and, ii) a magnetization magnitude that is not constant in time. We show,
+however, that both of these effects are naturally described by the
+Landau-Lifshitz-Bloch equation which links the LLG equation with the theory of
+critical phenomena and turns out to be a more realistic equation for
+magnetization dynamics at elevated temperatures.",0604508v1
+2007-02-20,Spin dynamics in a superconductor / ferromagnet proximity system,"The ferromagnetic resonance of thin sputtered Ni80Fe20 films grown on Nb is
+measured. By varying the temperature and thickness of the Nb the role of the
+superconductivity on the whole ferromagnetic layer in these heterostructures is
+explored. The change in the spin transport properties below the superconducting
+transition of the Nb is found to manifest itself in the Ni80Fe20 layer by a
+sharpening in the resonance of the ferromagnet, or a decrease in the effective
+Gilbert damping co-efficient. This dynamic proximity effect is in contrast to
+low frequency studies in these systems, where the effect of the superconductor
+is confined to a small region in the ferromagnet. We interpret this in terms of
+the spin pumping model.",0702461v1
+2007-02-21,"Domain wall mobility, stability and Walker breakdown in magnetic nanowires","We present an analytical calculation of the velocity of a single 180 degree
+domain wall in a magnetic structure with reduced thickness and/or lateral
+dimension under the combined action of an external applied magnetic field and
+an electrical current. As for the case of field-induced domain wall propagation
+in thick films, two motion regimes with different mobilities are obtained,
+below and far above the so-called Walker field. Additionally, for the case of
+current induced motion, a Walker-like current density threshold can be defined.
+When the dimensions of the system become comparable to the domain wall width,
+the threshold field and current density, stating the wall's internal structure
+stability, are reduced by the same geometrical demagnetising factor which
+accounts for the confinement. This points out the fact that the velocity
+dependence over an extended field/current range and the knowledge of the Walker
+breakdown are mandatory to draw conclusions about the phenomenological Gilbert
+damping parameter tuning the magnetisation dynamics.",0702492v1
+2001-01-09,Hysteresis in layered spring magnets,"This article addresses a problem of micromagnetics: the reversal of magnetic
+moments in layered spring magnets. A one-dimensional model is used of a film
+consisting of several atomic layers of a soft material on top of several atomic
+layers of a hard material. Each atomic layer is taken to be uniformly
+magnetized, and spatial inhomogeneities within an atomic layer are neglected.
+The state of such a system is described by a chain of magnetic spin vectors.
+Each spin vector behaves like a spinning top driven locally by the effective
+magnetic field and subject to damping (Landau-Lifshitz-Gilbert equation). A
+numerical integration scheme for the LLG equation is presented that is
+unconditionally stable and preserves the magnitude of the magnetization vector
+at all times. The results of numerical investigations for a bilayer in a
+rotating in-plane magnetic field show hysteresis with a basic period of $2\pi$
+at moderate fields and hysteresis with a basic period of $\pi$ at strong
+fields.",0101077v1
+2005-01-01,Equatorial and related non-equilibrium states in magnetization dynamics of ferromagnets: Generalization of Suhl's spin-wave instabilities,"We investigate the nonlinear dynamics underlying the evolution of a 2-D
+nanoscale ferromagnetic film with uniaxial anisotropy in the presence of
+perpendicular pumping. Considering the associated Landau-Lifshitz spin
+evolution equation with Gilbert damping together with Maxwell equation for the
+demagnetization field, we study the dynamics in terms of the stereographic
+variable. We identify several new fixed points for suitable choice of external
+field in a rotating frame of reference. In particular, we identify explicit
+equatorial and related fixed points of the spin vector in the plane transverse
+to the anisotropy axis when the pumping frequency coincides with the amplitude
+of the static parallel field. We then study the linear stability of these novel
+fixed points under homogeneous and spin wave perturbations and obtain a
+generalized Suhl's instability criterion, giving the condition for exponential
+growth of P-modes under spin wave perturbations. Two parameter phase diagrams
+(in terms of amplitudes of static parallel and oscillatory perpendicular
+magnetic fields) for stability are obtained, which differ qualitatively from
+those for the conventional ferromagnetic resonance near thermal equilibrium and
+are amenable to experimental tests.",0501002v2
+2002-12-30,Stochastic resonance in periodic potentials: realization in a dissipative optical lattice,"We have observed the phenomenon of stochastic resonance on the Brillouin
+propagation modes of a dissipative optical lattice. Such a mode has been
+excited by applying a moving potential modulation with phase velocity equal to
+the velocity of the mode. Its amplitude has been characterized by the
+center-of-mass (CM) velocity of the atomic cloud. At Brillouin resonance, we
+studied the CM-velocity as a function of the optical pumping rate at a given
+depth of the potential wells. We have observed a resonant dependence of the CM
+velocity on the optical pumping rate, corresponding to the noise strength. This
+corresponds to the experimental observation of stochastic resonance in a
+periodic potential in the low-damping regime.",0212156v1
+2007-05-03,Planar spin-transfer device with a dynamic polarizer,"In planar nano-magnetic devices magnetization direction is kept close to a
+given plane by the large easy-plane magnetic anisotropy, for example by the
+shape anisotropy in a thin film. In this case magnetization shows effectively
+in-plane dynamics with only one angle required for its description. Moreover,
+the motion can become overdamped even for small values of Gilbert damping. We
+derive the equations of effective in-plane dynamics in the presence of
+spin-transfer torques. The simplifications achieved in the overdamped regime
+allow to study systems with several dynamic magnetic pieces (``free layers'').
+A transition from a spin-transfer device with a static polarizer to a device
+with two equivalent magnets is observed. When the size difference between the
+magnets is less than critical, the device does not exhibit switching, but goes
+directly into the ``windmill'' precession state.",0705.0406v1
+2007-05-03,Effective attraction induced by repulsive interaction in a spin-transfer system,"In magnetic systems with dominating easy-plane anisotropy the magnetization
+can be described by an effective one dimensional equation for the in-plane
+angle. Re-deriving this equation in the presence of spin-transfer torques, we
+obtain a description that allows for a more intuitive understanding of
+spintronic devices' operation and can serve as a tool for finding new dynamic
+regimes. A surprising prediction is obtained for a planar ``spin-flip
+transistor'': an unstable equilibrium point can be stabilized by a current
+induced torque that further repels the system from that point. Stabilization by
+repulsion happens due to the presence of dissipative environment and requires a
+Gilbert damping constant that is large enough to ensure overdamped dynamics at
+zero current.",0705.0508v1
+2007-06-21,Spin pumping by a field-driven domain wall,"We calculate the charge current in a metallic ferromagnet to first order in
+the time derivative of the magnetization direction. Irrespective of the
+microscopic details, the result can be expressed in terms of the conductivities
+of the majority and minority electrons and the non-adiabatic spin transfer
+torque parameter $\beta$. The general expression is evaluated for the specific
+case of a field-driven domain wall and for that case depends strongly on the
+ratio of $\beta$ and the Gilbert damping constant. These results may provide an
+experimental method to determine this ratio, which plays a crucial role for
+current-driven domain-wall motion.",0706.3160v3
+2007-09-18,Theory of current-driven magnetization dynamics in inhomogeneous ferromagnets,"We give a brief account of recent developments in the theoretical
+understanding of the interaction between electric currents and inhomogeneous
+ferromagnetic order parameters. We start by discussing the physical origin of
+the spin torques responsible for this interaction and construct a
+phenomenological description. We then consider the electric current-induced
+ferromagnetic instability and domain-wall motion. Finally, we present a
+microscopic justification of the phenomenological description of current-driven
+magnetization dynamics, with particular emphasis on the dissipative terms, the
+so-called Gilbert damping $\alpha$ and the $\beta$ component of the adiabatic
+current-driven torque.",0709.2937v2
+2008-02-12,Temperature dependent magnetization dynamics of magnetic nanoparticles,"Recent experimental and theoretical studies show that the switching behavior
+of magnetic nanoparticles can be well controlled by external time-dependent
+magnetic fields. In this work, we inspect theoretically the influence of the
+temperature and the magnetic anisotropy on the spin-dynamics and the switching
+properties of single domain magnetic nanoparticles (Stoner-particles). Our
+theoretical tools are the Landau-Lifshitz-Gilbert equation extended as to deal
+with finite temperatures within a Langevine framework. Physical quantities of
+interest are the minimum field amplitudes required for switching and the
+corresponding reversal times of the nanoparticle's magnetic moment. In
+particular, we contrast the cases of static and time-dependent external fields
+and analyze the influence of damping for a uniaxial and a cubic anisotropy.",0802.1740v1
+2008-09-25,The theory of magnetic field induced domain-wall propagation in magnetic nanowires,"A global picture of magnetic domain wall (DW) propagation in a nanowire
+driven by a magnetic field is obtained: A static DW cannot exist in a
+homogeneous magnetic nanowire when an external magnetic field is applied. Thus,
+a DW must vary with time under a static magnetic field. A moving DW must
+dissipate energy due to the Gilbert damping. As a result, the wire has to
+release its Zeeman energy through the DW propagation along the field direction.
+The DW propagation speed is proportional to the energy dissipation rate that is
+determined by the DW structure. An oscillatory DW motion, either the precession
+around the wire axis or the breath of DW width, should lead to the speed
+oscillation.",0809.4311v1
+2008-10-08,Transverse spin diffusion in ferromagnets,"We discuss the dissipative diffusion-type term of the form
+$\mathbf{m}\times\nabla^2\partial_t\mathbf{m}$ in the phenomenological
+Landau-Lifshitz equation of ferromagnetic precession, which describes enhanced
+Gilbert damping of finite-momentum spin waves. This term arises physically from
+itinerant-electron spin flows through a perturbed ferromagnetic configuration
+and can be understood to originate in the ferromagnetic spin pumping in the
+continuum limit. We develop a general phenomenology as well as provide
+microscopic theory for the Stoner and s-d models of ferromagnetism, taking into
+account disorder and electron-electron scattering. The latter is manifested in
+our problem through the Coulomb drag between the spin bands. The spin diffusion
+is identified in terms of the transverse spin conductivity, in analogy with the
+Einstein relation in the kinetic theory.",0810.1340v2
+2008-10-16,Interaction of reed and acoustic resonator in clarinetlike systems,"Sound emergence in clarinetlike instruments is investigated in terms of
+instability of the static regime. Various models of reed-bore coupling are
+considered, from the pioneering work of Wilson and Beavers [""Operating modes of
+the clarinet"", J. Acoust. Soc. Am. 56, 653--658 (1974)] to more recent modeling
+including viscothermal bore losses and vena contracta at the reed inlet. The
+pressure threshold above which these models may oscillate as well as the
+frequency of oscillation at threshold are calculated. In addition to Wilson and
+Beavers' previous conclusions concerning the role of the reed damping in the
+selection of the register the instrument will play on, the influence of the
+reed motion induced flow is also emphasized, particularly its effect on playing
+frequencies, contributing to reduce discrepancies between Wilson and Beavers'
+experimental results and theory, despite discrepancies still remain concerning
+the pressure threshold. Finally, analytical approximations of the oscillating
+solution based on Fourier series expansion are obtained in the vicinity of the
+threshold of oscillation. This allows to emphasize the conditions which
+determine the nature of the bifurcation (direct or inverse) through which the
+note may emerge, with therefore important consequences on the musical playing
+performances.",0810.2870v1
+2008-11-21,Spin Transfer Torque as a Non-Conservative Pseudo-Field,"In this paper we show that the spin transfer torque can be described by a
+pseudo magnetic field, proportional to the magnetic moment of the itinerant
+electrons that enters the Landau-Lifshitz-Gilbert equation in the same way as
+other external or internal magnetic fields. However, unlike an ordinary
+magnetic field, which is always conservative in nature, the spin torque induced
+pseudo field may have both conservative and non-conservative components. We
+further show that the magnetic moment of itinerant electrons develops an
+out-of-plane component only at non-equilibrium and this component is
+responsible for the Slonczewski type switching that acts against the damping
+and is always non-conservative. On the other hand, the in-plane components of
+the pseudo field exist both at equilibrium and out-of-equilibrium, and are
+responsible for the field like term. For tunnel based devices, this term
+results in lower switching current for anti-parallel (AP) to parallel (P)
+switching compared to P to AP, even when the torque magnitudes are completely
+symmetric with voltage.",0811.3472v1
+2008-12-13,Non-Adiabatic Spin Transfer Torque in Real Materials,"The motion of simple domain walls and of more complex magnetic textures in
+the presence of a transport current is described by the
+Landau-Lifshitz-Slonczewski (LLS) equations. Predictions of the LLS equations
+depend sensitively on the ratio between the dimensionless material parameter
+$\beta$ which characterizes non-adiabatic spin-transfer torques and the Gilbert
+damping parameter $\alpha$. This ratio has been variously estimated to be close
+to 0, close to 1, and large compared to 1. By identifying $\beta$ as the
+influence of a transport current on $\alpha$, we derive a concise, explicit and
+relatively simple expression which relates $\beta$ to the band structure and
+Bloch state lifetimes of a magnetic metal. Using this expression we demonstrate
+that intrinsic spin-orbit interactions lead to intra-band contributions to
+$\beta$ which are often dominant and can be (i) estimated with some confidence
+and (ii) interpreted using the ""breathing Fermi surface"" model.",0812.2570v1
+2009-05-29,Ferromagnetic resonance linewidth in ultrathin films with perpendicular magnetic anisotropy,"Transition metal ferromagnetic films with perpendicular magnetic anisotropy
+(PMA) have ferromagnetic resonance (FMR) linewidths that are one order of
+magnitude larger than soft magnetic materials, such as pure iron (Fe) and
+permalloy (NiFe) thin films. A broadband FMR setup has been used to investigate
+the origin of the enhanced linewidth in Ni$|$Co multilayer films with PMA. The
+FMR linewidth depends linearly on frequency for perpendicular applied fields
+and increases significantly when the magnetization is rotated into the film
+plane. Irradiation of the film with Helium ions decreases the PMA and the
+distribution of PMA parameters. This leads to a great reduction of the FMR
+linewidth for in-plane magnetization. These results suggest that fluctuations
+in PMA lead to a large two magnon scattering contribution to the linewidth for
+in-plane magnetization and establish that the Gilbert damping is enhanced in
+such materials ($\alpha \approx 0.04$, compared to $\alpha \approx 0.002$ for
+pure Fe).",0905.4779v2
+2009-10-01,Spin motive forces and current fluctuations due to Brownian motion of domain walls,"We compute the power spectrum of the noise in the current due to spin motive
+forces by a fluctuating domain wall. We find that the power spectrum of the
+noise in the current is colored, and depends on the Gilbert damping, the spin
+transfer torque parameter $\beta$, and the domain-wall pinning potential and
+magnetic anisotropy. We also determine the average current induced by the
+thermally-assisted motion of a domain wall that is driven by an external
+magnetic field. Our results suggest that measuring the power spectrum of the
+noise in the current in the presence of a domain wall may provide a new method
+for characterizing the current-to-domain-wall coupling in the system.",0910.0163v1
+2009-10-08,Fast domain wall propagation under an optimal field pulse in magnetic nanowires,"We investigate field-driven domain wall (DW) propagation in magnetic
+nanowires in the framework of the Landau-Lifshitz-Gilbert equation. We propose
+a new strategy to speed up the DW motion in a uniaxial magnetic nanowire by
+using an optimal space-dependent field pulse synchronized with the DW
+propagation. Depending on the damping parameter, the DW velocity can be
+increased by about two orders of magnitude compared the standard case of a
+static uniform field. Moreover, under the optimal field pulse, the change in
+total magnetic energy in the nanowire is proportional to the DW velocity,
+implying that rapid energy release is essential for fast DW propagation.",0910.1477v2
+2009-11-24,Origin of adiabatic and non-adiabatic spin transfer torques in current-driven magnetic domain wall motion,"A consistent theory to describe the correlated dynamics of quantum mechanical
+itinerant spins and semiclassical local magnetization is given. We consider the
+itinerant spins as quantum mechanical operators, whereas local moments are
+considered within classical Lagrangian formalism. By appropriately treating
+fluctuation space spanned by basis functions, including a zero-mode wave
+function, we construct coupled equations of motion for the collective
+coordinate of the center-of-mass motion and the localized zero-mode coordinate
+perpendicular to the domain wall plane. By solving them, we demonstrate that
+the correlated dynamics is understood through a hierarchy of two time scales:
+Boltzmann relaxation time when a non-adiabatic part of the spin-transfer torque
+appears, and Gilbert damping time when adiabatic part comes up.",0911.4628v1
+2010-01-26,Strategies and tolerances of spin transfer torque switching,"Schemes of switching nanomagnetic memories via the effect of spin torque with
+various polarizations of injected electrons are studied. Simulations based on
+macrospin and micromagnetic theories are performed and compared. We demonstrate
+that switching with perpendicularly polarized current by short pulses and free
+precession requires smaller time and energy than spin torque switching with
+collinear in plane spin polarization; it is also found to be superior to other
+kinds of memories. We study the tolerances of switching to the magnitude of
+current and pulse duration. An increased Gilbert damping is found to improve
+tolerances of perpendicular switching without increasing the threshold current,
+unlike in plane switching.",1001.4578v1
+2010-03-31,Magnonic Crystal with Two-Dimensional Periodicity as a Waveguide for Spin Waves,"We describe a simple method of including dissipation in the spin wave band
+structure of a periodic ferromagnetic composite, by solving the Landau-Lifshitz
+equation for the magnetization with the Gilbert damping term. We use this
+approach to calculate the band structure of square and triangular arrays of Ni
+nanocylinders embedded in an Fe host. The results show that there are certain
+bands and special directions in the Brillouin zone where the spin wave lifetime
+is increased by more than an order of magnitude above its average value. Thus,
+it may be possible to generate spin waves in such composites decay especially
+slowly, and propagate especially large distances, for certain frequencies and
+directions in ${\bf k}$-space.",1003.6092v1
+2010-07-20,Precessing vortices and antivortices in ferromagnetic elements,"A micromagnetic numerical study of the precessional motion of the vortex and
+antivortex states in soft ferromagnetic circular nanodots is presented using
+Landau-Lifshitz-Gilbert dynamics. For sufficiently small dot thickness and
+diameter, the vortex state is metastable and spirals toward the center of the
+dot when its initial displacement is smaller than a critical value. Otherwise,
+the vortex spirals away from the center and eventually exits the dot which
+remains in a state of in-plane magnetization (ground state). In contrast, the
+antivortex is always unstable and performs damped precession resulting in
+annihilation at the dot circumference. The vortex and antivortex frequencies of
+precession are compared with the response expected on the basis of Thiele's
+theory of collective coordinates. We also calculate the vortex restoring force
+with an explicit account of the magnetostatic and exchange interaction on the
+basis of the 'rigid' vortex and 'two-vortices side charges free' models and
+show that neither model explains the vortex translation mode eigenfrequency for
+nanodots of sufficiently small size.",1007.3508v1
+2010-10-07,Power optimization for domain wall motion in ferromagnetic nanowires,"The current mediated domain-wall dynamics in a thin ferromagnetic wire is
+investigated. We derive the effective equations of motion of the domain wall.
+They are used to study the possibility to optimize the power supplied by
+electric current for the motion of domain walls in a nanowire. We show that a
+certain resonant time-dependent current moving a domain wall can significantly
+reduce the Joule heating in the wire, and thus it can lead to a novel proposal
+for the most energy efficient memory devices. We discuss how Gilbert damping,
+non-adiabatic spin transfer torque, and the presence of Dzyaloshinskii-Moriya
+interaction can effect this power optimization.",1010.1537v1
+2011-03-30,Spin motive forces due to magnetic vortices and domain walls,"We study spin motive forces, i.e, spin-dependent forces, and voltages induced
+by time-dependent magnetization textures, for moving magnetic vortices and
+domain walls. First, we consider the voltage generated by a one-dimensional
+field-driven domain wall. Next, we perform detailed calculations on
+field-driven vortex domain walls. We find that the results for the voltage as a
+function of magnetic field differ between the one-dimensional and vortex domain
+wall. For the experimentally relevant case of a vortex domain wall, the
+dependence of voltage on field around Walker breakdown depends qualitatively on
+the ratio of the so-called $\beta$-parameter to the Gilbert damping constant,
+and thus provides a way to determine this ratio experimentally. We also
+consider vortices on a magnetic disk in the presence of an AC magnetic field.
+In this case, the phase difference between field and voltage on the edge is
+determined by the $\beta$ parameter, providing another experimental method to
+determine this quantity.",1103.5858v3
+2011-07-04,Influence of randomness and retardation on the FMR-linewidth,"The theory predicts that the spin-wave lifetime $\tau_L$ and the linewidth of
+ferromagnetic resonance $\Delta B$ can be governed by random fields and spatial
+memory. To that aim the effective field around which the magnetic moments
+perform a precession is superimposed by a stochastic time dependent magnetic
+field with finite correlation time. The magnetization dynamics is altered by
+inclusion of a spatial memory effect monitoring a non-local interaction of size
+$\xi$. The underlying Landau-Lifshitz-Gilbert equation (LLG) is modified
+accordingly. The stochastic LLG is equivalent to a Fokker-Planck equation which
+enables to calculate the mean values of the magnetization vector. Within the
+spin-wave approximation we present an analytical solution for the excitation
+energy and its damping. The lifetime and the linewidth are analyzed depending
+on the strength of the random field $D$ and its correlation time $\tau_c$ as
+well as the retardation strength $\Gamma_0$ and the size $\xi$. Whereas
+$\tau_L$ decreases with increasing $D$, retardation strength $\Gamma_0$ and
+$\tau_c$, the lifetime is enhanced for growing width $\xi$ of the spatial
+retardation kernel. In the same manner we calculate the experimentally
+measurable linewidth $\Delta B$ is increased strongly when the correlation time
+$\tau_c$ ranges in the nanosecond interval.",1107.0638v1
+2011-11-18,Charge and Spin Transport in Magnetic Tunnel Junctions: Microscopic Theory,"We study the charge and spin currents passing through a magnetic tunnel
+junction (MTJ) on the basis of a tight-binding model. The currents are
+evaluated perturbatively with respect to the tunnel Hamiltonian. The charge
+current has the form $A[\bm M_1(t)\times\dot{\bm M}_1(t)]\cdot\bm M_2+B\dot{\bm
+M}_1(t)\cdot\bm M_2$, where $\bm M_1(t)$ and $\bm M_2$ denote the directions of
+the magnetization in the free layer and fixed layer, respectively. The constant
+$A$ vanishes when one or both layers are insulators, {while the constant $B$
+disappears when both layers are insulators or the same ferromagnets.} The first
+term in the expression for charge current represents dissipation driven by the
+effective electric field induced by the dynamic magnetization. In addition,
+from an investigation of the spin current, we obtain the microscopic expression
+for the enhanced Gilbert damping constant $\varDelta \alpha$. We show that
+$\varDelta\alpha$ is proportional to the tunnel conductance and depends on the
+bias voltage.",1111.4295v2
+2012-01-17,Magnetic vortex echoes: application to the study of arrays of magnetic nanostructures,"We propose the use of the gyrotropic motion of vortex cores in nanomagnets to
+produce a magnetic echo, analogous to the spin echo in NMR. This echo occurs
+when an array of nanomagnets, e.g., nanodisks, is magnetized with an in-plane
+(xy) field, and after a time \tau a field pulse inverts the core magnetization;
+the echo is a peak in M_{xy} at t=2\tau. Its relaxation times depend on the
+inhomogeneity, on the interaction between the nanodots and on the Gilbert
+damping constant \alpha. Its feasibility is demonstrated using micromagnetic
+simulation. To illustrate an application of the echoes, we have determined the
+inhomogeneity and measured the magnetic interaction in an array of nanodisks
+separated by a distance d, finding a d^{-n} dependence, with n\approx 4.",1201.3553v1
+2012-02-15,Current-induced motion of a transverse magnetic domain wall in the presence of spin Hall effect,"We theoretically study the current-induced dynamics of a transverse magnetic
+domain wall in bi-layer nanowires consisting of a ferromagnet on top of a
+nonmagnet having strong spin-orbit coupling. Domain wall dynamics is
+characterized by two threshold current densities, $J_{th}^{WB}$ and
+$J_{th}^{REV}$, where $J_{th}^{WB}$ is a threshold for the chirality switching
+of the domain wall and $J_{th}^{REV}$ is another threshold for the reversed
+domain wall motion caused by spin Hall effect. Domain walls with a certain
+chirality may move opposite to the electron-flow direction with high speed in
+the current range $J_{th}^{REV} < J < J_{th}^{WB}$ for the system designed to
+satisfy the conditions $J_{th}^{WB} > J_{th}^{REV}$ and \alpha > \beta, where
+\alpha is the Gilbert damping constant and \beta is the nonadiabaticity of spin
+torque. Micromagnetic simulations confirm the validity of analytical results.",1202.3450v1
+2012-04-23,Rotating skyrmion lattices by spin torques and field or temperature gradients,"Chiral magnets like MnSi form lattices of skyrmions, i.e. magnetic whirls,
+which react sensitively to small electric currents j above a critical current
+density jc. The interplay of these currents with tiny gradients of either the
+magnetic field or the temperature can induce a rotation of the magnetic pattern
+for j>jc. Either a rotation by a finite angle of up to 15 degree or -- for
+larger gradients -- a continuous rotation with a finite angular velocity is
+induced. We use Landau-Lifshitz-Gilbert equations extended by extra damping
+terms in combination with a phenomenological treatment of pinning forces to
+develop a theory of the relevant rotational torques. Experimental neutron
+scattering data on the angular distribution of skyrmion lattices suggests that
+continuously rotating domains are easy to obtain in the presence of remarkably
+small currents and temperature gradients.",1204.5051v1
+2012-07-09,Thermal vortex dynamics in thin circular ferromagnetic nanodisks,"The dynamics of gyrotropic vortex motion in a thin circular nanodisk of soft
+ferromagnetic material is considered. The demagnetization field is calculated
+using two-dimensional Green's functions for the thin film problem and fast
+Fourier transforms. At zero temperature, the dynamics of the
+Landau-Lifshitz-Gilbert equation is simulated using fourth order Runge-Kutta
+integration. Pure vortex initial conditions at a desired position are obtained
+with a Lagrange multipliers constraint. These methods give accurate estimates
+of the vortex restoring force constant $k_F$ and gyrotropic frequency, showing
+that the vortex core motion is described by the Thiele equation to very high
+precision. At finite temperature, the second order Heun algorithm is applied to
+the Langevin dynamical equation with thermal noise and damping. A spontaneous
+gyrotropic motion takes place without the application of an external magnetic
+field, driven only by thermal fluctuations. The statistics of the vortex radial
+position and rotational velocity are described with Boltzmann distributions
+determined by $k_F$ and by a vortex gyrotropic mass $m_G=G^2/k_F$,
+respectively, where $G$ is the vortex gyrovector.",1207.2192v2
+2013-02-19,Chirality Sensitive Domain Wall Motion in Spin-Orbit Coupled Ferromagnets,"Using the Lagrangian formalism, we solve analytically the equations of motion
+for current-induced domain-wall dynamics in a ferromagnet with Rashba
+spin-orbit coupling. An exact solution for the domain wall velocity is
+provided, including the effect of non-equilibrium conduction electron
+spin-density, Gilbert damping, and the Rashba interaction parameter. We
+demonstrate explicitly that the influence of spin-orbit interaction can be
+qualitatively different from the role of non-adiabatic spin-torque in the sense
+that the former is sensitive to the chirality of the domain wall whereas the
+latter is not: the domain wall velocity shows a reentrant behavior upon
+changing the chirality of the domain wall. This could be used to experimentally
+distinguish between the spin-orbit and non-adiabatic contribution to the wall
+speed. A quantitative estimate for the attainable domain wall velocity is
+given, based on an experimentally relevant set of parameters for the system.",1302.4744v1
+2013-12-17,Control of the in-plane anisotropy in off-stoichiometric NiMnSb,"NiMnSb is a ferromagnetic half-metal which, because of its rich anisotropy
+and very low Gilbert damping, is a promising candidate for applications in
+information technologies. We have investigated the in-plane anisotropy
+properties of thin, MBE-grown NiMnSb films as a function of their Mn
+concentration. Using ferromagnetic resonance (FMR) to determine the uniaxial
+and four-fold anisotropy fields, 2KU/Ms and 2K1/Ms, we find that a small
+variation in composition is sufficient to change the film from primarily
+four-fold to primarily uniaxial behavior, allowing for continuous tuning of the
+anisotropy. This provides valuable flexibility in designing new device
+geometries.",1312.4781v2
+2014-05-09,Current-induced magnetization dynamics in two magnetic insulators separated by a normal metal,"We study the dynamics of spin valves consisting of two layers of magnetic
+insulators separated by a normal metal in the macrospin model. A current
+through the spacer generates a spin Hall current that can actuate the
+magnetization via the spin-transfer torque. We derive expressions for the
+effective Gilbert damping and the critical currents for the onset of
+magnetization dynamics including the effects of spin pumping that can be tested
+by ferromagnetic resonance experiments. The current generates an amplitude
+asymmetry between the in-phase and out-of-phase modes. We briefly discuss
+superlattices of metals and magnetic insulators.",1405.2267v1
+2014-05-25,Spin Hall phenomenology of magnetic dynamics,"We study the role of spin-orbit interactions in the coupled magnetoelectric
+dynamics of a ferromagnetic film coated with an electrical conductor. While the
+main thrust of this work is phenomenological, several popular simple models are
+considered microscopically in some detail, including Rashba and Dirac
+two-dimensional electron gases coupled to a magnetic insulator, as well as a
+diffusive spin Hall system. We focus on the long-wavelength magnetic dynamics
+that experiences current-induced torques and produces fictitious electromotive
+forces. Our phenomenology provides a suitable framework for analyzing
+experiments on current-induced magnetic dynamics and reciprocal charge pumping,
+including the effects of magnetoresistance and Gilbert-damping anisotropies,
+without a need to resort to any microscopic considerations or modeling.
+Finally, some remarks are made regarding the interplay of spin-orbit
+interactions and magnetic textures.",1405.6354v2
+2014-08-21,Brownian motion of massive skyrmions forced by spin polarized currents,"We report on the thermal effects on the motion of current-driven massive
+magnetic skyrmions. The reduced equation for the motion of skyrmion has the
+form of a stochastic generalized Thiele's equation. We propose an ansatz for
+the magnetization texture of a non-rigid single skyrmion that depends linearly
+with the velocity. By utilizing this ansatz it is is found that the mass of
+skyrmion is closely related to intrinsic skyrmion parameters, such as Gilbert
+damping, skyrmion-charge and dissipative force. We have found an exact
+expression for the average drift velocity as well as the mean-square velocity
+of the skyrmion. The longitudinal and transverse mobility of skyrmions for
+small spin-velocity of electrons is also determined and found to be independent
+of the skyrmion mass.",1408.4861v2
+2014-11-11,Capturing of a Magnetic Skyrmion with a Hole,"Magnetic whirls in chiral magnets, so-called skyrmions, can be manipulated by
+ultrasmall current densities. Here we study both analytically and numerically
+the interactions of a single skyrmion in two dimensions with a small hole in
+the magnetic layer. Results from micromagnetic simulations are in good
+agreement with effective equations of motion obtained from a generalization of
+the Thiele approach. Skyrmion-defect interactions are described by an effective
+potential with both repulsive and attractive components. For small current
+densities a previously pinned skyrmion stays pinned whereas an unpinned
+skyrmion moves around the impurities and never gets captured. For higher
+current densities, j_c1 < j < j_c2, however, single holes are able to capture
+moving skyrmions. The maximal cross section is proportional to the skyrmion
+radius and to Sqrt(alpha), where alpha is the Gilbert damping. For j > j_c2 all
+skyrmions are depinned. Small changes of the magnetic field strongly change the
+pinning properties, one can even reach a regime without pinning, j_c2=0. We
+also show that a small density of holes can effectively accelerate the motion
+of the skyrmion and introduce a Hall effect for the skyrmion.",1411.2857v1
+2014-12-01,Dissipation due to pure spin-current generated by spin pumping,"Based on spin-dependent transport theory and thermodynamics, we develop a
+generalized theory of the Joule heating in the presence of a spin current.
+Along with the conventional Joule heating consisting of an electric current and
+electrochemical potential, it is found that the spin current and spin
+accumulation give an additional dissipation because the spin-dependent
+scatterings inside bulk and ferromagnetic/nonmagnetic interface lead to a
+change of entropy. The theory is applied to investigate the dissipation due to
+pure spin-current generated by spin pumping across a
+ferromagnetic/nonmagnetic/ferromagnetic multilayer. The dissipation arises from
+an interface because the spin pumping is a transfer of both the spin angular
+momentum and the energy from the ferromagnet to conduction electrons near the
+interface. It is found that the dissipation is proportional to the enhancement
+of the Gilbert damping constant by spin pumping.",1412.0688v1
+2015-01-30,Head-to-Head Domain Wall Structures in Wide Permalloy Strips,"We analyze the equilibrium micromagnetic domain wall structures encountered
+in Permalloy strips of a wide range of thicknesses and widths, with strip
+widths up to several micrometers. By performing an extensive set of
+micromagnetic simulations, we show that the equilibrium phase diagram of the
+domain wall structures exhibits in addition to the previously found structures
+(symmetric and asymmetric transverse walls, vortex wall) also double vortex and
+triple vortex domain walls for large enough strip widths and thicknesses. Also
+several metastable domain wall structures are found for wide and/or thick
+strips. We discuss the details of the relaxation process from random
+magnetization initial states towards the stable domain wall structure, and show
+that our results are robust with respect to changes of e.g. the magnitude of
+the Gilbert damping constant and details of the initial conditions.",1501.07731v1
+2015-02-19,Characterization of spin relaxation anisotropy in Co using spin pumping,"Ferromagnets are believed to exhibit strongly anisotropic spin relaxation,
+with relaxation lengths for spin longitudinal to magnetization significantly
+longer than those for spin transverse to magnetization. Here we characterize
+the anisotropy of spin relaxation in Co using the spin pumping contribution to
+Gilbert damping in noncollinearly magnetized Py$_{1-x}$Cu$_{x}$/Cu/Co trilayer
+structures. The static magnetization angle between Py$_{1-x}$Cu$_{x}$ and Co,
+adjusted under field bias perpendicular to film planes, controls the
+projections of longitudinal and transverse spin current pumped from
+Py$_{1-x}$Cu$_{x}$ into Co. We find nearly isotropic absorption of pure spin
+current in Co using this technique; fits to a diffusive transport model yield
+the longitudinal spin relaxation length $< 2$ nm in Co. The longitudinal spin
+relaxation lengths found are an order of magnitude smaller than those
+determined by current-perpendicular-to-planes giant magnetoresistance
+measurements, but comparable with transverse spin relaxation lengths in Co
+determined by spin pumping.",1502.05687v3
+2015-04-01,Multiscale modeling of ultrafast element-specific magnetization dynamics of ferromagnetic alloys,"A hierarchical multiscale approach to model the magnetization dynamics of
+ferromagnetic ran- dom alloys is presented. First-principles calculations of
+the Heisenberg exchange integrals are linked to atomistic spin models based
+upon the stochastic Landau-Lifshitz-Gilbert (LLG) equation to calculate
+temperature-dependent parameters (e.g., effective exchange interactions,
+damping param- eters). These parameters are subsequently used in the
+Landau-Lifshitz-Bloch (LLB) model for multi-sublattice magnets to calculate
+numerically and analytically the ultrafast demagnetization times. The developed
+multiscale method is applied here to FeNi (permalloy) as well as to copper-
+doped FeNi alloys. We find that after an ultrafast heat pulse the Ni sublattice
+demagnetizes faster than the Fe sublattice for the here-studied FeNi-based
+alloys.",1504.00199v1
+2015-05-04,High-topological-number magnetic skyrmions and topologically protected dissipative structure,"The magnetic skyrmion with the topological number of unity ($Q=1$) is a
+well-known nanometric swirling spin structure in the nonlinear $\sigma$ model
+with the Dzyaloshinskii-Moriya interaction. Here, we show that magnetic
+skyrmion with the topological number of two ($Q=2$) can be created and
+stabilized by applying vertical spin-polarized current though it cannot exist
+as a static stable excitation. Magnetic skyrmion with $Q=2$ is a nonequilibrium
+dynamic object, subsisting on a balance between the energy injection from the
+current and the energy dissipation by the Gilbert damping. Once it is created,
+it becomes a topologically protected object against fluctuations of various
+variables including the injected current itself. Hence, we may call it a
+topologically protected dissipative structure. We also elucidate the nucleation
+and destruction mechanisms of the magnetic skyrmion with $Q=2$ by studying the
+evolutions of the magnetization distribution, the topological charge density as
+well as the energy density. Our results will be useful for the study of the
+nontrivial topology of magnetic skyrmions with higher topological numbers.",1505.00522v2
+2015-08-06,Large spin-wave bullet in a ferrimagnetic insulator driven by spin Hall effect,"Due to its transverse nature, spin Hall effects (SHE) provide the possibility
+to excite and detect spin currents and magnetization dynamics even in magnetic
+insulators. Magnetic insulators are outstanding materials for the investigation
+of nonlinear phenomena and for novel low power spintronics applications because
+of their extremely low Gilbert damping. Here, we report on the direct imaging
+of electrically driven spin-torque ferromagnetic resonance (ST-FMR) in the
+ferrimagnetic insulator Y$_3$Fe$_5$O$_{12}$ based on the excitation and
+detection by SHEs. The driven spin dynamics in Y$_3$Fe$_5$O$_{12}$ is directly
+imaged by spatially-resolved microfocused Brillouin light scattering (BLS)
+spectroscopy. Previously, ST-FMR experiments assumed a uniform precession
+across the sample, which is not valid in our measurements. A strong spin-wave
+localization in the center of the sample is observed indicating the formation
+of a nonlinear, self-localized spin-wave `bullet'.",1508.01427v1
+2015-12-02,Bose-Einstein Condensation of Magnons Pumped by the Bulk Spin Seebeck Effect,"We propose inducing Bose-Einstein condensation of magnons in a magnetic
+insulator by a heat flow oriented toward its boundary. At a critical heat flux,
+the oversaturated thermal gas of magnons accumulated at the boundary
+precipitates the condensate, which then grows gradually as the thermal bias is
+dialed up further. The thermal magnons thus pumped by the magnonic bulk (spin)
+Seebeck effect must generally overcome both the local Gilbert damping
+associated with the coherent magnetic dynamics as well as the radiative
+spin-wave losses toward the magnetic bulk, in order to achieve the threshold of
+condensation. We quantitatively estimate the requisite bias in the case of the
+ferrimagnetic yttrium iron garnet, discuss different physical regimes of
+condensation, and contrast it with the competing (so-called Doppler-shift) bulk
+instability.",1512.00557v1
+2016-01-10,"Interfacial Dzyaloshinskii-Moriya interaction, surface anisotropy energy,and spin pumping at spin orbit coupled Ir/Co interface","The interfacial Dzyaloshinskii-Moriya interaction (iDMI), surface anisotropy
+energy, and spin pumping at the Ir/Co interface are experimentally investigated
+by performing Brillouin light scattering. Contrary to previous reports, we
+suggest that the sign of the iDMI at the Ir/Co interface is the same as in the
+case of the Pt/Co interface. We also find that the magnitude of the iDMI energy
+density is relatively smaller than in the case of the Pt/Co interface, despite
+the large strong spin-orbit coupling (SOC) of Ir. The saturation magnetization
+and the perpendicular magnetic anisotropy (PMA) energy are significantly
+improved due to a strong SOC. Our findings suggest that an SOC in an Ir/Co
+system behaves in different ways for iDMI and PMA. Finally, we determine the
+spin pumping effect at the Ir/Co interface, and it increases the Gilbert
+damping constant from 0.012 to 0.024 for 1.5 nmthick Co.",1601.02210v3
+2016-02-23,Relaxation of a classical spin coupled to a strongly correlated electron system,"A classical spin which is antiferromagnetically coupled to a system of
+strongly correlated conduction electrons is shown to exhibit unconventional
+real-time dynamics which cannot be described by Gilbert damping. Depending on
+the strength of the local Coulomb interaction, the two main electronic
+dissipation channels, transport of excitations via correlated hopping and via
+excitations of correlation-induced magnetic moments, become active on largely
+different time scales. We demonstrate that this can lead to a prethermalization
+scenario which so far has been observed in purely electronic systems only and
+which is governed here by proximity to the divergent magnetic time scale in the
+infinite-U limit.",1602.07317v2
+2016-05-12,Classical limit of Rabi nutations in spins of ferromagnets,"Rabi oscillations describe the interaction of a two-level system with a
+rotating electromagnetic field. As such, they serve as the principle method for
+manipulating quantum bits. By using a combination of femtosecond laser pulses
+and microwave excitations, we have observed the classical form of Rabi
+nutations in a ferromagnetic system whose equations of motion mirror the case
+of a precessing quantum two-level system. Key to our experiments is the
+selection of a subset of spins that is in resonance with the microwave
+excitation and whose coherence time is thereby extended. Taking advantage of
+Gilbert damping, the relaxation times are further increased such that
+mode-locking takes place. The observation of such Rabi nutations is the first
+step towards potential applications based on phase-coherent spin manipulation
+in ferromagnets.",1605.03996v1
+2016-06-07,The temperature dependence of FeRh's transport properties,"The finite-temperature transport properties of FeRh compounds are
+investigated by first-principles Density Functional Theory-based calculations.
+The focus is on the behavior of the longitudinal resistivity with rising
+temperature, which exhibits an abrupt decrease at the metamagnetic transition
+point, $T = T_m$ between ferro- and antiferromagnetic phases. A detailed
+electronic structure investigation for $T \geq 0$ K explains this feature and
+demonstrates the important role of (i) the difference of the electronic
+structure at the Fermi level between the two magnetically ordered states and
+(ii) the different degree of thermally induced magnetic disorder in the
+vicinity of $T_m$, giving different contributions to the resistivity. To
+support these conclusions, we also describe the temperature dependence of the
+spin-orbit induced anomalous Hall resistivity and Gilbert damping parameter.
+For the various response quantities considered the impact of thermal lattice
+vibrations and spin fluctuations on their temperature dependence is
+investigated in detail. Comparison with corresponding experimental data finds
+in general a very good agreement.",1606.02072v1
+2016-09-05,Coarsening dynamics of topological defects in thin Permalloy films,"We study the dynamics of topological defects in the magnetic texture of
+rectangular Permalloy thin film elements during relaxation from random
+magnetization initial states. Our full micromagnetic simulations reveal complex
+defect dynamics during relaxation towards the stable Landau closure domain
+pattern, manifested as temporal power-law decay, with a system-size dependent
+cut-off time, of various quantities. These include the energy density of the
+system, and the number densities of the different kinds of topological defects
+present in the system. The related power-law exponents assume non-trivial
+values, and are found to be different for the different defect types. The
+exponents are robust against a moderate increase in the Gilbert damping
+constant and introduction of quenched structural disorder. We discuss details
+of the processes allowed by conservation of the winding number of the defects,
+underlying their complex coarsening dynamics.",1609.01094v1
+2016-09-27,Anomalous Feedback and Negative Domain Wall Resistance,"Magnetic induction can be regarded as a negative feedback effect, where the
+motive-force opposes the change of magnetic flux that generates the
+motive-force. In artificial electromagnetics emerging from spintronics,
+however, this is not necessarily the case. By studying the current-induced
+domain wall dynamics in a cylindrical nanowire, we show that the spin
+motive-force exerting on electrons can either oppose or support the applied
+current that drives the domain wall. The switching into the anomalous feedback
+regime occurs when the strength of the dissipative torque {\beta} is about
+twice the value of the Gilbert damping constant {\alpha}. The anomalous
+feedback manifests as a negative domain wall resistance, which has an analogy
+with the water turbine.",1609.08250v1
+2016-10-04,Magnetomechanical coupling and ferromagnetic resonance in magnetic nanoparticles,"We address the theory of the coupled lattice and magnetization dynamics of
+freely suspended single-domain nanoparticles. Magnetic anisotropy generates
+low-frequency satellite peaks in the microwave absorption spectrum and a
+blueshift of the ferromagnetic resonance (FMR) frequency. The low-frequency
+resonances are very sharp with maxima exceeding that of the FMR, because their
+magnetic and mechanical precessions are locked, thereby suppressing Gilbert
+damping. Magnetic nanoparticles can operate as nearly ideal motors that convert
+electromagnetic into mechanical energy. The Barnett/Einstein-de Haas effect is
+significant even in the absence of a net rotation.",1610.01072v2
+2016-10-05,Finite-dimensional colored fluctuation-dissipation theorem for spin systems,"When nano-magnets are coupled to random external sources, their magnetization
+becomes a random variable, whose properties are defined by an induced
+probability density, that can be reconstructed from its moments, using the
+Langevin equation, for mapping the noise to the dynamical degrees of freedom.
+When the spin dynamics is discretized in time, a general
+fluctuation-dissipation theorem, valid for non-Markovian noise, can be
+established, even when zero modes are present. We discuss the subtleties that
+arise, when Gilbert damping is present and the mapping between noise and spin
+degrees of freedom is non--linear.",1610.01622v1
+2017-03-31,Spin Seebeck effect in Y-type hexagonal ferrite thin films,"Spin Seebeck effect (SSE) has been investigated in thin films of two
+Y-hexagonal ferrites Ba$_2$Zn$_{2}$Fe$_{12}$O$_{22}$ (Zn2Y) and
+Ba$_2$Co$_{2}$Fe$_{12}$O$_{22}$ (Co2Y) deposited by a spin-coating method on
+SrTiO$_3$(111) substrate. The selected hexagonal ferrites are both
+ferrimagnetic with similar magnetic moments at room temperature and both
+exhibit easy magnetization plane normal to $c$-axis. Despite that, SSE signal
+was only observed for Zn2Y, whereas no significant SSE signal was detected for
+Co2Y. We tentatively explain this different behavior by a presence of two
+different magnetic ions in Co2Y, whose random distribution over octahedral
+sites interferes the long range ordering and enhances the Gilbert damping
+constant. The temperature dependence of SSE for Zn2Y was measured and analyzed
+with regard to the heat flux and temperature gradient relevant to the SSE
+signal.",1703.10903v1
+2017-06-02,Power Loss for a Periodically Driven Ferromagnetic Nanoparticle in a Viscous Fluid: the Finite Anisotropy Aspects,"The joint magnetic and mechanical motion of a ferromagnetic nanoparticle in a
+viscous fluid is considered within the dynamical approach. The equation based
+on the total momentum conservation law is used for the description of the
+mechanical rotation, while the modified Landau-Lifshitz-Gilbert equation is
+utilized for the description of the internal magnetic dynamics. The exact
+expressions for the particles trajectories and the power loss are obtained in
+the linear approximation. The comparison with the results of other widespread
+approaches, such as the model of fixed particle and the model of frozen
+magnetic moment, is performed. It is established that in the small oscillations
+mode the damping precession of the nanopartile magnetic moment is the main
+channel of energy dissipation, but the motion of the nanoparticle easy axis can
+significantly influence the value of the resulting power loss.",1706.00777v2
+2017-06-07,Adiabatic and nonadiabatic spin torques induced by spin-triplet supercurrent,"We study spin transfer torques induced by a spin-triplet supercurrent in a
+magnet with the superconducting proximity effect. By a perturbative approach,
+we show that spin-triplet correlations realize new types of torques, which are
+analogous to the adiabatic and non-adiabatic ($\beta$) torques, without
+extrinsic spin-flip scattering. Remarkable advantages compared to conventional
+spin-transfer torques are highlighted in domain wall manipulation. Oscillatory
+motions of a domain wall do not occur for a small Gilbert damping, and the
+threshold current density to drive its motion becomes zero in the absence of
+extrinsic pinning potentials due to the nonadiabatic torque controlled by the
+triplet correlations.",1706.02296v2
+2017-06-26,Perpendicular magnetic anisotropy in insulating ferrimagnetic gadolinium iron garnet thin films,"We present experimental control of the magnetic anisotropy in a gadolinium
+iron garnet (GdIG) thin film from in-plane to perpendicular anisotropy by
+simply changing the sample temperature. The magnetic hysteresis loops obtained
+by SQUID magnetometry measurements unambiguously reveal a change of the
+magnetically easy axis from out-of-plane to in-plane depending on the sample
+temperature. Additionally, we confirm these findings by the use of temperature
+dependent broadband ferromagnetic resonance spectroscopy (FMR). In order to
+determine the effective magnetization, we utilize the intrinsic advantage of
+FMR spectroscopy which allows to determine the magnetic anisotropy independent
+of the paramagnetic substrate, while magnetometry determines the combined
+magnetic moment from film and substrate. This enables us to quantitatively
+evaluate the anisotropy and the smooth transition from in-plane to
+perpendicular magnetic anisotropy. Furthermore, we derive the temperature
+dependent $g$-factor and the Gilbert damping of the GdIG thin film.",1706.08488v1
+2017-09-07,Tunable spin pumping in exchange coupled magnetic trilayers,"Magnetic thin films at ferromagnetic resonance (FMR) leak angular momentum,
+which may be absorbed by adjacent layers. This phenomenon, known as spin
+pumping, is manifested by an increase in the resonance linewidth ($\Delta H$),
+and the closely related Gilbert damping. Another effect of this transfer of
+spin currents is a dynamical and long-range coupling that can drive two
+magnetic layers into a collective precession when their FMR frequencies
+coincide. A collective behavior is also found in magnetic trilayers with
+interlayer exchange coupling (IEC). In this study we investigate the interplay
+between IEC and spin pumping, using Co/Cu/Py pseudo-spin values. We employ
+broadband FMR spectroscopy to explore both the frequency and coupling-strength
+dependence of $\Delta H$. Our observations show that there exists a cut-off
+frequency, set by the IEC strength, below which the precession is truly
+collective and the spin pumping is suppressed. These results demonstrate that
+it is possible to control the spin pumping efficiency by varying the frequency
+or the interlayer exchange coupling.",1709.02295v1
+2017-10-30,Probe of Spin Dynamics in Superconducting NbN Thin Films via Spin Pumping,"The emerging field of superconductor (SC) spintronics has attracted intensive
+attentions recently. Many fantastic spin dependent properties in SC have been
+discovered, including the observation of large magnetoresistance, long spin
+lifetimes and the giant spin Hall effect in SC, as well as spin supercurrent in
+Josephson junctions, etc. Regarding the spin dynamic in SC films, few studies
+has been reported yet. Here, we report the investigation of the spin dynamics
+in an s-wave superconducting NbN film via spin pumping from an adjacent
+insulating ferromagnet GdN layer. A profound coherence peak of the Gilbert
+damping is observed slightly below the superconducting critical temperature of
+the NbN layer, which is consistent with recent theoretical studies. Our results
+further indicate that spin pumping could be a powerful tool for investigating
+the spin dynamics in 2D crystalline superconductors.",1710.10833v2
+2017-11-17,Shot noise of charge and spin transport in a junction with a precessing molecular spin,"Magnetic molecules and nanomagnets can be used to influence the electronic
+transport in mesoscopic junction. In a magnetic field the precessional motion
+leads to resonances in the dc- and ac-transport properties of a nanocontact, in
+which the electrons are coupled to the precession. Quantities like the
+dc-conductance or the ac-response provide valuable information like the level
+structure and the coupling parameters. Here, we address the current noise
+properties of such contacts. This encompasses the charge current and
+spin-torque shot noise, which both show a step-like behavior as functions of
+bias voltage and magnetic field. The charge current noise shows pronounced dips
+around the steps, which we trace back to interference effects of electron in
+quasienergy levels coupled by the molecular spin precession. We show that some
+components of the noise of the spin-torque currents are directly related to the
+Gilbert damping and, hence, are experimentally accessible. Our results show
+that the noise characteristics allow to investigate in more detail the
+coherence of spin transport in contacts containing magnetic molecules.",1711.06759v2
+2018-02-05,Cooper-Pair Spin Current in a Strontium Ruthenate Heterostructure,"It has been recognized that the condensation of spin-triplet Cooper pairs
+requires not only the broken gauge symmetry but also the spin ordering as well.
+One consequence of this is the possibility of the Cooper-pair spin current
+analogous to the magnon spin current in magnetic insulators, the analogy also
+extending to the existence of the Gilbert damping of the collective
+spin-triplet dynamics. The recently fabricated heterostructure of the thin film
+of the itinerant ferromagnet SrRuO3 on the bulk Sr2RuO4, the best-known
+candidate material for the spin-triplet superconductor, offers a promising
+platform for generating such spin current. We will show how such
+heterostructure allows us to not only realize the long-range spin valve but
+also electrically drive the collective spin mode of the spin-triplet order
+parameter. Our proposal represents both a new realization of the spin
+superfluidity and a transport signature of the spin-triplet superconductivity.",1802.01599v1
+2018-02-12,Spin-orbit torque and spin pumping in YIG/Pt with interfacial insertion layers,"We experimentally investigate spin-orbit torque and spin pumping in
+Y$_3$Fe$_5$O$_{12}$(YIG)/Pt bilayers with ultrathin insertion layers at the
+interface. An insertion layer of Cu suppresses both spin-orbit torque and spin
+pumping, whereas an insertion layer of Ni$_{80}$Fe$_{20}$ (permalloy, Py)
+enhances them, in a quantitatively consistent manner with the reciprocity of
+the two spin transmission processes. However, we observe a large enhancement of
+Gilbert damping with the insertion of Py that cannot be accounted for solely by
+spin pumping, suggesting significant spin-memory loss due to the interfacial
+magnetic layer. Our findings indicate that the magnetization at the YIG-metal
+interface strongly influences the transmission and depolarization of pure spin
+current.",1802.03865v3
+2018-06-01,Dirac-Surface-State Modulated Spin Dynamics in a Ferrimagnetic Insulator at Room Temperature,"This work demonstrates dramatically modified spin dynamics of magnetic
+insulator (MI) by the spin-momentum locked Dirac surface states of the adjacent
+topological insulator (TI) which can be harnessed for spintronic applications.
+As the Bi-concentration x is systematically tuned in 5 nm thick (BixSb1-x)2Te3
+TI film, the weight of the surface relative to bulk states peaks at x = 0.32
+when the chemical potential approaches the Dirac point. At this concentration,
+the Gilbert damping constant of the precessing magnetization in 10 nm thick
+Y3Fe5O12 MI film in the MI/TI heterostructures is enhanced by an order of
+magnitude, the largest among all concentrations. In addition, the MI acquires
+additional strong magnetic anisotropy that favors the in-plane orientation with
+similar Bi-concentration dependence. These extraordinary effects of the Dirac
+surface states distinguish TI from other materials such as heavy metals in
+modulating spin dynamics of the neighboring magnetic layer.",1806.00151v1
+2018-08-23,Reduced thermal stability of antiferromagnetic nanostructures,"Antiferromagnetic materials hold promising prospects in novel types of
+spintronics applications. Assessing the stability of antiferromagnetic
+nanostructures against thermal excitations is a crucial aspect of designing
+devices with a high information density. Here we use theoretical calculations
+and numerical simulations to determine the mean switching time of
+antiferromagnetic nanoparticles in the superparamagnetic limit. It is
+demonstrated that the thermal stability is drastically reduced compared to
+ferromagnetic particles in the limit of low Gilbert damping, attributed to the
+exchange enhancement of the attempt frequencies. It is discussed how the system
+parameters have to be engineered in order to optimize the switching rates in
+antiferromagnetic nanoparticles.",1808.07665v3
+2018-09-17,On the speed of domain walls in thin nanotubes: the transition from the linear to the magnonic regime,"Numerical simulations of domain wall propagation in thin nanotubes when an
+external magnetic field is applied along the nanotube axis have shown an
+unexpected behavior described as a transition from a linear to a magnonic
+regime. As the applied magnetic field increases, the initial regime of linear
+growth of the speed with the field is followed by a sudden change in slope
+accompanied by the emission of spin waves. In this work an analytical formula
+for the speed of the domain wall that explains this behavior is derived by
+means of an asymptotic study of the Landau Lifshitz Gilbert equation for thin
+nanotubes. We show that the dynamics can be reduced to a one dimensional
+hyperbolic reaction diffusion equation, namely, the damped double Sine Gordon
+equation, which shows the transition to the magnonic regime as the domain wall
+speed approaches the speed of spin waves. This equation has been previously
+found to describe domain wall propagation in weak ferromagnets with the
+mobility proportional to the Dzyaloshinskii-Moriya interaction constant, for
+Permalloy nanotubes the mobility is proportional to the nanotube radius.",1809.06278v3
+2018-10-19,Magnon properties of random alloys,"We study magnon properties in terms of spin stiffness, Curie temperatures and
+magnon spectrum of Fe-Ni, Co-Ni and Fe-Co random alloys using a combination of
+electronic structure calculations and atomistic spin dynamics simulations.
+Influence of the disorder are studied in detail by use of large supercells with
+random atomic arrangement. It is found that disorder affects the magnon
+spectrum in vastly different ways depending on the system. Specifically, it is
+more pronounced in Fe-Ni alloys compared to Fe-Co alloys. In particular, the
+magnon spectrum at room temperature in Permalloy (Fe$_{20}$Ni$_{80}$) is found
+to be rather diffuse in a large energy interval while in Fe$_{75}$Co$_{25}$ it
+forms sharp branches. Fe-Co alloys are very interesting from a technological
+point of view due to the combination of large Curie temperatures and very low
+calculated Gilbert damping of $\sim$0.0007 at room temperature for Co
+concentrations around 20--30\%.",1810.08487v1
+2018-11-09,Switching of biaxial synthetic antiferromagnets: a micromagentic study,"We simulate the switching behavior of nanoscale synthetic antiferromagnets
+(SAFs), inspired by recent experimental progress in spin-orbit-torque switching
+of crystal antiferromagnets. The SAF consists of two ferromagnetic thin films
+with in-plane biaxial anisotropy and interlayer exchange coupling. Staggered
+field-like Rashba spin-orbit torques from the opposite surfaces of the SAF
+induce a canted net magnetization, which triggers an orthogonal torque that
+drives 90$^\circ$ switching of the N\'eel vector. Such dynamics driven by the
+field-like spin-orbit torque allows for faster switching with increased Gilbert
+damping, without a significant detrimental increase of the threshold switching
+current density. Our results point to the potential of SAFs as model systems,
+based on simple ferromagnetic metals, to mimic antiferromagnetic device
+physics.",1811.04094v2
+2018-12-03,Microscopic theory of magnon-drag electron flow in ferromagnetic metals,"A temperature gradient applied to a ferromagnetic metal induces not only
+independent flows of electrons and magnons but also drag currents because of
+their mutual interaction. In this paper, we present a microscopic study of the
+electron flow induced by the drag due to magnons. The analysis is based on the
+$s$-$d$ model, which describes conduction electrons and magnons coupled via the
+$s$-$d$ exchange interaction. Magnetic impurities are introduced in the
+electron subsystem as a source of spin relaxation. The obtained magnon-drag
+electron current is proportional to the entropy of magnons and to $\alpha -
+\beta$ (more precisely, to $1 - \beta/\alpha$), where $\alpha$ is the Gilbert
+damping constant and $\beta$ is the dissipative spin-transfer torque parameter.
+This result almost coincides with the previous phenomenological result based on
+the magnonic spin-motive forces, and consists of spin-transfer and
+momentum-transfer contributions, but with a slight disagreement in the former.
+The result is interpreted in terms of the nonequilibrium spin chemical
+potential generated by nonequilibrium magnons.",1812.00720v1
+2019-01-17,Spin transport parameters of NbN thin films characterised by spin pumping experiments,"We present measurements of ferromagnetic-resonance - driven spin pumping and
+inverse spin-Hall effect in NbN/Y3Fe5O12 (YIG) bilayers. A clear enhancement of
+the (effective) Gilbert damping constant of the thin-film YIG was observed due
+to the presence of the NbN spin sink. By varying the NbN thickness and
+employing spin-diffusion theory, we have estimated the room temperature values
+of the spin diffusion length and the spin Hall angle in NbN to be 14 nm and
+-1.1 10-2, respectively. Furthermore, we have determined the spin-mixing
+conductance of the NbN/YIG interface to be 10 nm-2. The experimental
+quantification of these spin transport parameters is an important step towards
+the development of superconducting spintronic devices involving NbN thin films.",1901.05753v1
+2019-02-12,Characterization of spin wave propagation in (111) YIG thin films with large anisotropy,"We report on long-range spin wave (SW) propagation in nanometer-thick yttrium
+iron garnet (YIG) film with an ultralow Gilbert damping. The knowledge of a
+wavenumber value $|\vec{k}|$ is essential for designing SW devices. Although
+determining the wavenumber $|\vec{k}|$ in experiments like Brillouin light
+scattering spectroscopy is straightforward, quantifying the wavenumber in
+all-electrical experiments has not been widely commented upon so far. We
+analyze magnetostatic spin wave (SW) propagation in YIG films in order to
+determine the SW wavenumber $|\vec{k}|$ excited by the coplanar waveguide. We
+show that it is crucial to consider the influence of magnetic anisotropy fields
+present in YIG thin films for precise determination of SW wavenumber. With the
+proposed methods we find that experimentally derived values of $|\vec{k}|$ are
+in perfect agreement with that obtained from electromagnetic simulation only if
+anisotropy fields are included.",1902.04608v1
+2019-03-20,Nonlinear magnetization dynamics driven by strong terahertz fields,"We present a comprehensive experimental and numerical study of magnetization
+dynamics triggered in a thin metallic film by single-cycle terahertz pulses of
+$\sim20$ MV/m electric field amplitude and $\sim1$ ps duration. The
+experimental dynamics is probed using the femtosecond magneto-optical Kerr
+effect (MOKE), and it is reproduced numerically using macrospin simulations.
+The magnetization dynamics can be decomposed in three distinct processes: a
+coherent precession of the magnetization around the terahertz magnetic field,
+an ultrafast demagnetization that suddenly changes the anisotropy of the film,
+and a uniform precession around the equilibrium effective field that is relaxed
+on the nanosecond time scale, consistent with a Gilbert damping process.
+Macrospin simulations quantitatively reproduce the observed dynamics, and allow
+us to predict that novel nonlinear magnetization dynamics regimes can be
+attained with existing table-top terahertz sources.",1903.08395v2
+2019-04-11,Measurement of spin mixing conductance in Ni$_{81}$Fe$_{19}$/$α$-W and Ni$_{81}$Fe$_{19}$/$β$-W heterostrucutures via ferromagnetic resonance,"We present measurements of interfacial Gilbert damping due to the spin
+pumping effect in Ni$_{81}$Fe$_{19}$/W heterostructures. Measurements were
+compared for heterostructures in which the crystallographic phase of W, either
+$\alpha$(bcc)-W or $\beta$(A15)-W, was enriched through deposition conditions
+and characterized using X-ray diffraction (XRD) and high-resolution
+cross-sectional transmission electron microscopy (HR-XTEM). Single phase
+Ni$_{81}$Fe$_{19}$/$\alpha$-W heterostructures could be realized, but
+heterostructures with $\beta$-W were realized as mixed $\alpha$-$\beta$ phase.
+The spin mixing conductances (SMC) for W at interfaces with Ni$_{81}$Fe$_{19}$
+were found to be significantly lower than those for similarly heavy metals such
+as Pd and Pt, but comparable to those for Ta, and independent of enrichment in
+the $\beta$ phase.",1904.05950v2
+2019-05-26,Influence of field-like torque in synchronization of spin torque oscillators,"The magnetization dynamics of two parallelly coupled spin torque oscillators,
+destabilization of steady states and removal of multistability, are
+investigated by taking into account the influence of field-like torque. It is
+shown that the existence of such torque can cancel the effect of damping and
+can, therefore, cause the oscillators to exhibit synchronized oscillations in
+response to direct current. Further, our results show that the presence of
+field-like torque enhances the power and Q-factor of the synchronized
+oscillations. The validity of the above results is confirmed by numerical and
+analytical studies based on the stochastic Landau-Lifshitz-Gilbert-Slonczewski
+equation.",1905.10804v2
+2019-05-30,Sub-nanosecond switching in a cryogenic spin-torque spin-valve memory element with a dilute permalloy free layer,"We present a study of the pulsed current switching characteristics of
+spin-valve nanopillars with in-plane magnetized dilute permalloy and undiluted
+permalloy free layers in the ballistic regime at low temperature. The dilute
+permalloy free layer device switches much faster: the characteristic switching
+time for a permalloy free (Ni0.83Fe0.17) layer device is 1.18 ns, while that
+for a dilute permalloy ([Ni0.83Fe0.17]0.6Cu0.4) free layer device is 0.475 ns.
+A ballistic macrospin model can capture the data trends with a reduced spin
+torque asymmetry parameter, reduced spin polarization and increased Gilbert
+damping for the dilute permalloy free layer relative to the permalloy devices.
+Our study demonstrates that reducing the magnetization of the free layer
+increases the switching speed while greatly reducing the switching energy and
+shows a promising route toward even lower power magnetic memory devices
+compatible with superconducting electronics.",1905.13262v1
+2019-07-05,Theory for shift current of bosons: Photogalvanic spin current in ferrimagnetic and antiferromagnetic insulators,"We theoretically study the optical generation of dc spin current (i.e., a
+spin-current solar cell) in ordered antiferromagnetic and ferrimagnetic
+insulators, motivated by a recent study on the laser-driven spinon spin current
+in noncentrosymmetric quantum spin chains [H. Ishizuka and M. Sato, Phys. Rev.
+Lett. 122, 197702 (2019)]. Using a non-linear response theory for magnons, we
+analyze the dc spin current generated by a linearly-polarized electromagnetic
+wave (typically, terahertz or gigahertz waves). Considering noncentrosymmetric
+two-sublattice magnets as an example, we find a finite dc spin current
+conductivity at $T=0$, where no thermally-excited magnons exist; this is in
+contrast to the case of the spinon spin current, in which the optical
+transition of the Fermi degenerate spinons plays an essential role. We find
+that the dc spin-current conductivity is insensitive to the Gilbert damping,
+i.e., it may be viewed as a shift current carried by bosonic particles
+(magnons). Our estimate shows that an electric-field intensity of
+$E\sim10^4-10^6$ V/cm is sufficient for an observable spin current. Our theory
+indicates that the linearly-polarized electromagnetic wave generally produces a
+dc spin current in noncentrosymmetric magnetic insulators.",1907.02734v1
+2019-07-10,Temperature dependence of magnetic resonance in ferrimagnetic GdFeCo alloys,"We provide a macroscopic theory and experimental results for magnetic
+resonances of antiferromagnetically-coupled ferrimagnets. Our theory, which
+interpolates the dynamics of antiferromagnets and ferromagnets smoothly, can
+describe ferrimagnetic resonances across the angular momentum compensation
+point. We also present experimental results for spin-torque induced
+ferrimagnetic resonance at several temperatures. The spectral analysis based on
+our theory reveals that the Gilbert damping parameter, which has been
+considered to be strongly temperature dependent, is insensitive to temperature.
+We envision that our work will facilitate further investigation of
+ferrimagnetic dynamics by providing a theoretical framework suitable for a
+broad range of temperatures.",1907.04540v1
+2019-07-11,Improving the Signal-to-noise Ratio for Heat-Assisted Magnetic Recording by Optimizing a High/Low Tc bilayer structure,"We optimize the recording medium for heat-assisted magnetic recording by
+using a high/low $T_{\mathrm{c}}$ bilayer structure to reduce AC and DC noise.
+Compared to a former work, small Gilbert damping $\alpha=0.02$ is considered
+for the FePt like hard magnetic material. Atomistic simulations are performed
+for a cylindrical recording grain with diameter $d=5\,$nm and height $h=8\,$nm.
+Different soft magnetic material compositions are tested and the amount of hard
+and soft magnetic material is optimized. The results show that for a soft
+magnetic material with $\alpha_{\mathrm{SM}}=0.1$ and
+$J_{ij,\mathrm{SM}}=7.72\times 10^{-21}\,$J/link a composition with $50\%$ hard
+and $50\%$ soft magnetic material leads to the best results. Additionally, we
+analyse how much the areal density can be improved by using the optimized
+bilayer structure compared to the pure hard magnetic recording material. It
+turns out that the optimized bilayer design allows an areal density that is
+$1\,$Tb/in$^2$ higher than that of the pure hard magnetic material while
+obtaining the same SNR.",1907.05027v1
+2019-07-19,A cryogenic memory element based on an anomalous Josephson junction,"We propose a non-volatile memory element based on a lateral ferromagnetic
+Josephson junction with spin-orbit coupling and out-of-plane magnetization. The
+interplay between the latter and the intrinsic exchange field of the
+ferromagnet leads to a magnetoelectric effect that couples the charge current
+through the junction and its magnetization, such that by applying a current
+pulse the direction of the magnetic moment in F can be switched. The two memory
+states are encoded in the direction of the out-of-plane magnetization. With the
+aim to determine the optimal working temperature for the memory element, we
+explore the noise-induced effects on the averaged stationary magnetization by
+taking into account thermal fluctuations affecting both the Josephson phase and
+the magnetic moment dynamics. We investigate the switching process as a
+function of intrinsic parameters of the ferromagnet, such as the Gilbert
+damping and strength of the spin-orbit coupling, and proposed a non-destructive
+readout scheme based on a dc-SQUID. Additionally, we analyze a way to protect
+the memory state from external perturbations by voltage gating in systems with
+a both linear-in-momentum Rashba and Dresselhaus spin-orbit coupling.",1907.08454v2
+2019-07-23,Electron transport in high-entropy alloys: Al$_{x}$CrFeCoNi as a case study,"The high-entropy alloys Al$_{x}$CrFeCoNi exist over a broad range of Al
+concentrations ($0 < x < 2$). With increasing Al content their structure is
+changed from the fcc to bcc phase. We investigate the effect of such structural
+changes on transport properties including the residual resistivity and the
+anomalous Hall resistivity. We have performed a detailed comparison of the
+first-principles simulations with available experimental data. We show that the
+calculated residual resistivities for all studied alloy compositions are in a
+fair agreement with available experimental data as concerns both the
+resistivity values and concentration trends. We emphasize that a good agreement
+with experiment was obtained also for the anomalous Hall resistivity. We have
+completed study by estimation of the anisotropic magnetoresistance,
+spin-disorder resistivity, and Gilbert damping. The obtained results prove that
+the main scattering mechanism is due to the intrinsic chemical disorder whereas
+the effect of spin polarization on the residual resistivity is appreciably
+weaker.",1907.09731v1
+2019-09-11,Chaos in nanomagnet via feedback current,"Nonlinear magnetization dynamics excited by spin-transfer effect with
+feedback current is studied both numerically and analytically. The numerical
+simulation of the Landau-Lifshitz-Gilbert equation indicates the positive
+Lyapunov exponent for a certain range of the feedback rate, which identifies
+the existence of chaos in a nanostructured ferromagnet. Transient behavior from
+chaotic to steady oscillation is also observed in another range of the feedback
+parameter. An analytical theory is also developed, which indicates the
+appearance of multiple attractors in a phase space due to the feedback current.
+An instantaneous imbalance between the spin-transfer torque and damping torque
+causes a transition between the attractors, and results in the complex
+dynamics.",1909.05315v2
+2019-11-27,Ellipticity and Dissipation Effects in Magnon Spin Valves,"We consider alignment-dependent spin and heat transport across a magnon spin
+valve in the tunneling regime, i.e., a junction consisting of two weakly
+coupled ferromagnetic insulators. We determine the difference in spin and heat
+conductance between the parallel and antiparallel configuration of the
+magnetization direction. The dependence of these conductances on both the
+Gilbert damping and ellipticity is studied. We find that both magnon
+ellipticity and dissipation open channels for magnons to tunnel through in the
+antiparallel configuration. Our results highlight an important difference
+between electronic and magnon spin transport in spin-valve structures and may
+be important for the development of devices based on magnetic insulators.",1911.12017v2
+2020-03-24,Spin-transfer torque driven intrinsic localized spin excitations in the presence of field-like torque,"We study the existence of intrinsic localized one-spin excitation in the
+Heisenberg one-dimensional ferromagnetic spin chain in the presence of
+perpendicular and parallel external magnetic fields and current with
+spin-transfer torque and field-like torque. The
+Landau-Lifshitz-Gilbert-Slonczewski(LLGS) equation is exactly solved for the
+one spin excitation in the absence of onsite anisotropy for the excitations of
+spin with fields perpendicular and parallel to the chain. We show the removal
+of damping in the spin excitations by appropriately introducing current and
+also the enhancement of angular frequency of the oscillations due to field-like
+torque in the case of both perpendicular and parallel field. The exactness of
+the analytical results is verified by matching with numerical counterparts.
+Further, we numerically confirm the existence of in-phase and anti-phase stable
+synchronized oscillations for two spin-excitations in the presence of current
+with perpendicular field and field-like torque.",2003.11023v2
+2020-04-02,Stable solitons in a nearly PT-symmetric ferromagnet with spin-transfer torque,"We consider the Landau-Lifshitz equation for the spin torque oscillator - a
+uniaxial ferromagnet in an external magnetic field with polarised spin current
+driven through it. In the absence of the Gilbert damping, the equation turns
+out to be PT-symmetric. We interpret the PT-symmetry as a balance between gain
+and loss - and identify the gaining and losing modes. In the vicinity of the
+bifurcation point of a uniform static state of magnetisation, the PT-symmetric
+Landau-Lifshitz equation with a small dissipative perturbation reduces to a
+nonlinear Schr\""odinger equation with a quadratic nonlinearity. The analysis of
+the Schr\""odinger dynamics demonstrates that the spin torque oscillator
+supports stable magnetic solitons. The PT near-symmetry is crucial for the
+soliton stability: the addition of a finite dissipative term to the
+Landau-Lifshitz equation destabilises all solitons that we have found.",2004.01245v2
+2020-05-11,Manipulating 1-dimensinal skyrmion motion by external magnetic field gradient,"We have investigated an analytic formula of the 1-dimensional magnetic
+skyrmion dynamics under external magnetic field gradient. We find excellent
+agreement between the analytical model and micromagnetic simulation results for
+various magnetic parameters such as the magnetic field gradient, Gilbert
+damping constant. We also observe much faster velocity of the chiral domain
+wall (DW) motion. The chiral DW is exist with smaller interfacial
+Dzyaloshinskii-Moriya interaction energy density cases. These results provide
+to develop efficient control of skyrmion for spintronic devices.",2005.05011v1
+2020-07-08,Finite-frequency spin susceptibility and spin pumping in superconductors with spin-orbit relaxation,"Static spin susceptibility of superconductors with spin-orbit relaxation has
+been calculated in the seminal work of A.A. Abrikosov and L.P. Gor'kov [Sov.
+Phys. JETP, {\bf 15}, 752 (1962)]. Surprisingly the generalization of this
+result to finite frequencies has not been done despite being quite important
+for the modern topic of superconducting spintronics. The present paper fills
+this gap by deriving the analytical expression for spin susceptibility. The
+time-dependent spin response is shown to be captured by the quasiclassical
+Eilenberger equation with collision integrals corresponding to the ordinary and
+spin-orbit scattering. Using the developed formalism we study the linear spin
+pumping effect between the ferromagnet and the adjacent superconducting film.
+The consequences for understanding recent experiments demonstrating the
+modification of Gilbert damping by the superconducting correlations are
+discussed.",2007.04372v2
+2020-07-16,Thermal noise effects on the magnetization switching of a ferromagnetic anomalous Josephson junction,"We discuss the effects of thermal noise on the magnetic response of a lateral
+ferromagnetic Josephson junction with spin-orbit coupling and out-of-plane
+magnetization. The direction of the magnetic moment in the ferromagnetic layer
+can be inverted by using controlled current pulses. This phenomenon is due to
+the magnetoelectric effect that couples the flowing charge current and the
+magnetization of the ferromagnet. We investigate the magnetization reversal
+effect versus intrinsic parameters of the ferromagnet, such as the Gilbert
+damping and strength of the spin-orbit coupling. We estimate the magnetization
+reversing time and find the optimal values of the parameters for fast
+switching. With the aim of increasing the operation temperature we study the
+effects induced by thermal fluctuations on the averaged stationary
+magnetization, and find the conditions that make the system more robust against
+noise.",2007.08414v3
+2020-08-21,Integration and characterization of micron-sized YIG structures with very low Gilbert damping on arbitrary substrates,"We present a novel process that allows the transfer of monocrystalline
+yttrium-iron-garnet microstructures onto virtually any kind of substrate. The
+process is based on a recently developed method that allows the fabrication of
+freestanding monocrystalline YIG bridges on gadolinium-gallium-garnet. Here the
+bridges' spans are detached from the substrate by a dry etching process and
+immersed in a watery solution. Using drop casting the immersed YIG platelets
+can be transferred onto the substrate of choice, where the structures finally
+can be reattached and thus be integrated into complex devices or experimental
+geometries. Using time resolved scanning Kerr microscopy and inductively
+measured ferromagnetic resonance we can demonstrate that the structures retain
+their excellent magnetic quality. At room temperature we find a ferromagnetic
+resonance linewidth of $\mu_0\Delta H_{HWHM}\approx 195\,\mu T$ and we were
+even able to inductively measure magnon spectra on a single micron-sized
+yttrium-iron-garnet platelet at a temperature of 5 K. The process is flexible
+in terms of substrate material and shape of the structure. In the future this
+approach will allow for new types of spin dynamics experiments up to now
+unthinkable.",2008.09390v1
+2020-09-01,Quantum Brownian Motion for Magnets,"Spin precession in magnetic materials is commonly modelled with the classical
+phenomenological Landau-Lifshitz-Gilbert (LLG) equation. Based on a quantized
+spin+environment Hamiltonian, we here derive a general spin operator equation
+of motion that describes three-dimensional precession and damping and
+consistently accounts for effects arising from memory, coloured noise and
+quantum statistics. The LLG equation is recovered as its classical, Ohmic
+approximation. We further introduce resonant Lorentzian system--reservoir
+couplings that allow a systematic comparison of dynamics between Ohmic and
+non--Ohmic regimes. Finally, we simulate the full non-Markovian dynamics of a
+spin in the semi--classical limit. At low temperatures, our numerical results
+demonstrate a characteristic reduction and flattening of the steady state spin
+alignment with an external field, caused by the quantum statistics of the
+environment. The results provide a powerful framework to explore general
+three-dimensional dissipation in quantum thermodynamics.",2009.00600v2
+2020-09-30,Quantum hydrodynamics of spin winding,"An easy-plane spin winding in a quantum spin chain can be treated as a
+transport quantity, which propagates along the chain but has a finite lifetime
+due to phase slips. In a hydrodynamic formulation for the winding dynamics, the
+quantum continuity equation acquires a source term due to the transverse
+vorticity flow. The latter reflects the phase slips and generally compromises
+the global conservation law. A linear-response formalism for the nonlocal
+winding transport then reduces to a Kubo response for the winding flow along
+the spin chain, in conjunction with the parasitic vorticity flow transverse to
+it. One-dimensional topological hydrodynamics can be recovered when the
+vorticity flow is asymptotically small. Starting with a microscopic spin-chain
+formulation, we focus on the asymptotic behavior of the winding transport based
+on the renormalized sine-Gordon equation, incorporating phase slips as well as
+Gilbert damping. A generic electrical device is proposed to manifest this
+physics. We thus suggest winding conductivity as a tangible concept that can
+characterize low-energy dynamics in a broad class of quantum magnets.",2010.00144v1
+2020-11-29,Cross-sublattice Spin Pumping and Magnon Level Attraction in van der Waals Antiferromagnets,"We theoretically study spin pumping from a layered van der Waals
+antiferromagnet in its canted ground state into an adjacent normal metal. We
+find that the resulting dc spin pumping current bears contributions along all
+spin directions. Our analysis allows for detecting intra- and cross-sublattice
+spin-mixing conductances via measuring the two in-plane spin current
+components. We further show that sublattice symmetry-breaking Gilbert damping
+can be realized via interface engineering and induces a dissipative coupling
+between the optical and acoustic magnon modes. This realizes magnon level
+attraction and exceptional points in the system. Furthermore, the dissipative
+coupling and cross-sublattice spin pumping contrive to produce an
+unconventional spin current in the out-of-plane direction. Our findings provide
+a route to extract the spin mixing conductance matrix and uncovers the unique
+opportunities, such as level attraction, offered by van der Waals
+antiferromagnet-normal metal hybrids.",2011.14314v1
+2021-01-18,Topological electric driving of magnetization dynamics in insulators,"Established forms of electromagnetic coupling are usually conservative (in
+insulators) or dissipative (in metals and semiconductors). Here we point out
+the possibility of nondissipative electric driving of magnetization dynamics,
+if the valence electronic states have nontrivial topology in the combined space
+of crystal momentum and magnetization configuration. We provide a hybrid
+insulator system to demonstrate that the topology-based nonconservative
+electrical generalized force is capable of supporting sustained magnetization
+motion in the presence of Gilbert damping, with quantized and steady energy
+pumping into magnetization motion from the electric field. We also generalize
+our results to magnetic textures, and discuss electric field induced
+Dzyaloshinskii-Moriya interaction which can be nonconservative.",2101.07164v3
+2021-02-07,Spinterface Induced Modification in Magnetic Properties in Co40Fe40B20/Fullerene Bilayers,"Organic semiconductor/ferromagnetic bilayer thin films can exhibit novel
+properties due to the formation of the spinterface at the interface.
+Buckminsterfullerene (C60) has been shown to exhibit ferromagnetism at the
+interface when it is placed next to a ferromagnet (FM) such as Fe or Co.
+Formation of spinterface occurs due to the orbital hybridization and spin
+polarized charge transfer at the interface. In this work, we have demonstrated
+that one can enhance the magnetic anisotropy of the low Gilbert damping alloy
+CoFeB by introducing a C60 layer. We have shown that anisotropy increases by
+increasing the thickness of C60 which might be a result of the formation of
+spinterface. However, the magnetic domain structure remains same in the bilayer
+samples as compared to the reference CoFeB film.",2102.03914v4
+2021-02-15,Magnetodynamic properties of dipole-coupled 1D magnonic crystals,"Magnonic crystals are magnetic metamaterials, that provide a promising way to
+manipulate magnetodynamic properties by controlling the geometry of the
+patterned structures. Here, we study the magnetodynamic properties of 1D
+magnonic crystals consisting of parallel NiFe strips with different strip
+widths and separations. The strips couple via dipole-dipole interactions. As an
+alternative to experiments and/or micromagnetic simulations, we investigate the
+accuracy of a simple macrospin model. For the case of simple strips, a model
+with a single free parameter to account for an overestimation of the
+out-of-plane demagnetization of the magnonic lattice is described. By adjusting
+this parameter a good fit with experimental as well as micromagnetic results is
+obtained. Moreover, the Gilbert damping is found independent of the lattice
+constant however the inhomogeneous linewidth broadening found to increase with
+decreasing stripe separation.",2102.07712v2
+2021-05-24,Spin pumping of two-dimensional electron gas with Rashba and Dresselhaus spin-orbit interactions,"We theoretically consider spin pumping in a junction between a ferromagnetic
+insulator (FI) and a two-dimensional electron gas (2DEG) in which the Rashba
+and Dresselhaus spin-orbit interactions coexist. Using second-order
+perturbation theory, we derive an increase in linewidth in the case of an
+interfacial exchange coupling in a ferromagnetic resonance (FMR) experiment. We
+clarify how the enhancement of Gilbert damping depends on the resonant
+frequency and spin orientation of the FI. We show that this setup of an FMR
+experiment can provide information on the spin texture of 2DEG at the Fermi
+surface.",2105.11193v3
+2021-08-05,Spin-transfer torque driven localized spin excitations in the presence of field-like torque,"We study the existence of localized one-spin excitation in the Heisenberg
+one-dimensional ferromagnetic spin chain in the presence of perpendicular and
+parallel external magnetic fields and current with spin-transfer torque and
+field-like torque. The Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation is
+exactly solved for the one spin excitation in the absence of onsite anisotropy
+for the excitations of spin with fields perpendicular and parallel to the
+chain. We show the removal of damping in the spin excitations by appropriately
+introducing current and also the enhancement of angular frequency of the
+oscillations due to field-like torque in the case of both perpendicular and
+parallel field. The exactness of the analytical results is verified by matching
+with numerical counterparts. Further, we numerically confirm the existence of
+in-phase and anti-phase stable synchronized oscillations for two
+spin-excitations in the presence of current with perpendicular field and
+field-like torque. We also show that the one-spin excitation is stable against
+thermal noise and gets only slightly modified against thermal fluctuations.",2108.02380v1
+2021-09-07,Inertial spin dynamics in epitaxial cobalt films,"We investigate the spin dynamics driven by terahertz magnetic fields in
+epitaxial thin films of cobalt in its three crystalline phases. The terahertz
+magnetic field generates a torque on the magnetization which causes it to
+precess for about 1 ps, with a sub-picosecond temporal lag from the driving
+force. Then, the magnetization undergoes natural damped THz oscillations at a
+frequency characteristic of the crystalline phase. We describe the experimental
+observations solving the inertial Landau-Lifshitz-Gilbert equation. Using the
+results from the relativistic theory of magnetic inertia, we find that the
+angular momentum relaxation time $\eta$ is the only material parameter needed
+to describe all the experimental evidence. Our experiments suggest a
+proportionality between $\eta$ and the strength of the magneto-crystalline
+anisotropy.",2109.03076v2
+2021-09-26,Transition state dynamics of a driven magnetic free layer,"Magnetization switching in ferromagnetic structures is an important process
+for technical applications such as data storage in spintronics, and therefore
+the determination of the corresponding switching rates becomes essential. We
+investigate a free-layer system in an oscillating external magnetic field
+resulting in an additional torque on the spin. The magnetization dynamics
+including inertial damping can be described by the phenomenological Gilbert
+equation. The magnetization switching between the two stable orientations on
+the sphere then requires the crossing of a potential region characterized by a
+moving rank-1 saddle. We adopt and apply recent extensions of transition state
+theory for driven systems to compute both the time-dependent and average
+switching rates of the activated spin system in the saddle region.",2109.12605v1
+2021-12-24,Skyrmion nucleation on the surface of a topological insulator,"Skyrmion nucleation induced by spin-transfer torques at an interface of a
+topological insulator and a ferromagnetic insulator is investigated. Due to
+strong spin-orbit coupling on a surface of topological insulators, which
+enhances the effect of spin torques, efficient manipulation of skyrmions is
+expected, and therefore, topological insulators could provide the ideal
+platform to achieve high-performance skyrmionic devices. Using micromagnetic
+simulations and energetics, we evaluate properties of the skyrmion nucleation
+on a surface of topological insulators, such as nucleation time, critical
+electric field, and skyrmion numbers. We show that the nucleation time is
+inversely proportional to the applied electric field. We also identify the
+Gilbert damping and temperature dependencies of the critical field.
+Furthermore, we analytically evaluate the effect of the Dzyaloshinskii-Moriya
+interaction and demonstrate that the temperature dependence can be explained by
+the reduction of a magnon excitation gap due to the self-energy corrections.",2112.12967v2
+2021-12-10,Enhanced Planar Antenna Efficiency Through Magnetic Thin-Films,"This work proposes to use magnetic material as the substrate of planar
+antennas to overcome the platform effect caused by the conducting ground plane.
+The upper bound of the radiation efficiency of an electric-current-driven
+low-profile antenna is theoretically derived, which is inversely proportional
+to the Gilbert damping factor of the magnetic material. Meanwhile, the
+improvement of radiation due to the use of magnetic material is demonstrated by
+a three-dimensional (3D) multiphysics and multiscale time-domain model. The
+simulation results match the theoretical derivation, showing 25% radiation
+efficiency from a planar antenna backed by a FeGaB thin film with 2.56 um
+thickness. Furthermore, for conductive ferromagnetic materials, it is shown
+that the eddy current loss can be well suppressed by laminating the thin film
+into multiple layers. The radiation efficiency of the modeled antenna with a
+conductive ferromagnetic substrate is improved from 2.2% to 11.8% by dividing
+the substrate into 10 layers, with a ferromagnetic material fill factor of 93%.",2201.04932v1
+2022-03-07,Ultrafast optical observation of spin-pumping induced dynamic exchange coupling in ferromagnetic semiconductor/metal bilayer,"Spin angular momentum transfer in magnetic bilayers offers the possibility of
+ultrafast and low-loss operation for next-generation spintronic devices. We
+report the field- and temperature- dependent measurements on the magnetization
+precessions in Co$_2$FeAl/(Ga,Mn)As by time-resolved magneto-optical Kerr
+effect (TRMOKE). Analysis of the effective Gilbert damping and phase shift
+indicates a clear signature of an enhanced dynamic exchange coupling between
+the two ferromagnetic (FM) layers due to the reinforced spin pumping at
+resonance. The temperature dependence of the dynamic exchange-coupling reveals
+a primary contribution from the ferromagnetism in (Ga,Mn)As.",2203.03225v2
+2022-04-21,Transport theory for topological Josephson junctions with a Majorana qubit,"We construct a semiclassical theory for the transport of topological
+junctions starting from a microscopic Hamiltonian that comprehensively includes
+the interplay among the Majorana qubit, the Josephson phase, and the
+dissipation process. With the path integral approach, we derive a set of
+semiclassical equations of motion that can be used to calculate the time
+evolution of the Josephson phase and the Majorana qubit. In the equations we
+reveal rich dynamical phenomena such as the qubit induced charge pumping, the
+effective spin-orbit torque, and the Gilbert damping. We demonstrate the
+influence of these dynamical phenomena on the transport signatures of the
+junction. We apply the theory to study the Shapiro steps of the junction, and
+find the suppression of the first Shapiro step due to the dynamical feedback of
+the Majorana qubit.",2204.09923v1
+2022-11-04,Derivation of Interacting Two-Qubit Dynamics from Spin-Boson Model,"We derive damping equations of motion for interacting two-spin states from a
+spin-boson model in order to examine qubit dynamics in quantum computers. On
+the basis of the composite operator method, we develop the Caldeira-Leggett
+approach for open quantum systems so that the entanglement dynamics originated
+from the two-spin correlation can be taken. We demonstrate numerical results
+for time dependence on the two-spin dynamics. We find that the relaxation of
+the total spin is described by a quantum version of the Landau-Lifshitz-Gilbert
+equation for magnetic materials. We also find that a two-spin composite mode
+keeps oscillation even after the total spin has been fully relaxed. We thus
+conclude that the two-spin correlation due to the presence of the composite
+mode is stable against dissipation. We consider the mechanism of why the
+correlation is maintained.",2211.02490v1
+2023-02-06,Global solutions of the Landau--Lifshitz--Baryakhtar equation,"The Landau--Lifshitz--Baryakhtar (LLBar) equation is a generalisation of the
+Landau--Lifshitz--Gilbert and the Landau--Lifshitz--Bloch equations which takes
+into account contributions from nonlocal damping and is valid at moderate
+temperature below the Curie temperature. Therefore, it is used to explain some
+discrepancies between the experimental observations and the known theories in
+various problems on magnonics and magnetic domain-wall dynamics. In this paper,
+the existence and uniqueness of global weak, strong, and regular solutions to
+LLBar equation are proven. H\""older continuity of the solution is also
+discussed.",2302.02556v3
+2023-03-22,Twisted bilayer graphene reveals its flat bands under spin pumping,"The salient property of the electronic band structure of twisted bilayer
+graphene (TBG), at the so-called magic angle (MA), is the emergence of flat
+bands around the charge neutrality point. These bands are associated with the
+observed superconducting phases and the correlated insulating states. Scanning
+tunneling microscopy combined with angle resolved photoemission spectroscopy
+are usually used to visualize the flatness of the band structure of TBG at the
+MA. Here, we theoretically argue that spin pumping (SP) provides a direct probe
+of the flat bands of TBG and an accurate determination of the MA. We consider a
+junction separating a ferromagnetic insulator and a heterostructure of TBG
+adjacent to a monolayer of a transition metal dichalcogenide. We show that the
+Gilbert damping of the ferromagnetic resonance experiment, through this
+junction, depends on the twist angle of TBG, and exhibits a sharp drop at the
+MA. We discuss the experimental realization of our results which open the way
+to a twist switchable spintronics in twisted van der Waals heterostructures.",2303.12380v2
+2023-05-01,Coherent and incoherent magnons induced by strong ultrafast demagnetization in thin permalloy films,"Understanding spin dynamics on femto- and picosecond timescales offers new
+opportunities for faster and more efficient spintronic devices. Here, we
+experimentally investigate the coherent spin dynamics after ultrashort laser
+excitation by time-resolved magneto optical Kerr effect (TR-MOKE) in thin
+Ni80Fe20 films. We provide a detailed study of the magnetic field and pump
+fluence dependence of the coherent precessional dynamics. We show that the
+coherent precession lifetime increases with the applied external magnetic field
+which cannot be understood by viscous Gilbert damping of the coherent magnons.
+Instead, it can be explained by nonlinear magnon interactions and by the change
+in the fraction of incoherent magnons. This interpretation is in agreement with
+the observed trends of the coherent magnon amplitude and lifetime as a function
+of the exciting laser fluence. Our results provide a new insight into the
+magnetization relaxation processes in ferromagnetic thin films, which is of
+great importance for further spintronic applications.",2305.00814v2
+2023-07-15,Switching current distributions in ferromagnetic anomalous Josephson junctions,"We investigate the switching current distributions of ferromagnetic anomalous
+Josephson junctions subjected to a linearly increasing bias current. Our study
+uncovers a significant correlation between the position of the switching
+current distributions and crucial system parameters, such as the strength of
+the spin-orbit coupling and the Gilbert damping parameter. This indicates that
+these parameters can be directly determined through experimental measurements.
+By conducting a comprehensive analysis of the interplay among noise,
+magnetization, phase dynamics, and the statistical properties of the switching
+current distribution, we deepen our understanding of these intriguing cryogenic
+spintronics devices. These findings hold potential for applications in the
+field of quantum computing architectures and information processing
+technologies.",2307.07751v2
+2023-07-26,Oscillatory Edge Modes in Two Dimensional Spin-Torque Oscillator Arrays,"Spin torque oscillators (STOs) are dissipative magnetic systems that provide
+a natural platform for exploring non-Hermitian phenomena. We theoretically
+study a two-dimensional (2d) array of STOs and show that its dynamics can be
+mapped to a 2d, non-Hermitian Su-Schrieffer-Heeger (SSH) model. We calculate
+the energy spectrum and identify the one-dimensional (1d) edge states of our
+model, corresponding to auto-oscillation of STOs on the boundary of the system
+while the bulk oscillators do not activate. We show that tuning the Gilbert
+damping, injected spin current, and coupling between STOs allows for exploring
+the edge state properties under different parameter regimes. Furthermore, this
+system admits 1d edge states with non-uniform probability density, and we
+explore their properties in systems of different sizes. Additional symmetry
+analysis indicates that these states are not topologically protected but are
+nevertheless confined to the edge of the system, as the bulk is protected by
+PT-symmetry. These results indicate that 2d arrays of STOs may be useful to
+explore novel edge state behavior in dissipative systems.",2307.13876v1
+2024-03-25,Detection of spin pumping free of rectification and thermal artefacts in molecular-based ferromagnetic insulator V[TCNE]x~2,"The molecular-based ferrimagnetic insulator V(TCNE)x has gained recent
+interest for efficient spin-wave excitation due to its low Gilbert damping
+ratio a=4E-5, and narrow ferromagnetic resonance linewidth f=1Oe. Here we
+report a clean spin pumping signal detected on V(TCNE)x/metal bilayer
+structures, free from spin rectification or thermal artifacts. On-chip coupling
+of microwave power is achieved via a coplanar waveguide to measure the in-plane
+angle-dependence of the inverse spin-Hall effect under ferromagnetic resonance
+conditions with respect to a constant external magnetic field. A signature of
+pure spin current from V(TCNE)x is observed in both platinum and permalloy
+metal layers, demonstrating the utility of V(TCNE)x for magnon spintronics
+studies in molecule/solid-state heterostructures.",2403.16429v2
+2024-04-01,"Harnessing Interlayer Magnetic Coupling for Efficient, Field-Free Current-Induced Magnetization Switching in a Magnetic Insulator","Owing to the unique features of low Gilbert damping, long spin-diffusion
+lengths and zero Ohmic losses, magnetic insulators are promising candidate
+materials for next-generation spintronic applications. However, due to the
+localized magnetic moments and the complex metal-oxide interface between
+magnetic insulators and heavy metals, spin-functional Dzyaloshinskii-Moriya
+interactions or spin Hall and Edelstein effects are weak, which diminishes the
+performance of these typical building blocks for spintronic devices. Here, we
+exploit the exchange coupling between metallic and insulating magnets for
+efficient electrical manipulation of heavy metal/magnetic insulator
+heterostructures. By inserting a thin Co layer, we enhance the spin-orbit
+torque efficiency by more than 20 times, which significantly reduces the
+switching current density. Moreover, we demonstrate field-free current-induced
+magnetization switching caused by a symmetry-breaking non-collinear magnetic
+texture. Our work launches magnetic insulators as an alternative platform for
+low-power spintronic devices.",2404.00845v1
+1999-02-01,Damping Rates and Mean Free Paths of Soft Fermion Collective Excitations in a Hot Fermion-Gauge-Scalar Theory,"We study the transport coefficients, damping rates and mean free paths of
+soft fermion collective excitations in a hot fermion-gauge-scalar plasma with
+the goal of understanding the main physical mechanisms that determine transport
+of chirality in scenarios of non-local electroweak baryogenesis. The focus is
+on identifying the different transport coefficients for the different branches
+of soft collective excitations of the fermion spectrum. These branches
+correspond to collective excitations with opposite ratios of chirality to
+helicity and different dispersion relations. By combining results from the hard
+thermal loop (HTL) resummation program with a novel mechanism of fermion
+damping through heavy scalar decay, we obtain a robust description of the
+different damping rates and mean free paths for the soft collective excitations
+to leading order in HTL and lowest order in the Yukawa coupling. The space-time
+evolution of wave packets of collective excitations unambiguously reveals the
+respective mean free paths. We find that whereas both the gauge and scalar
+contribution to the damping rates are different for the different branches, the
+difference of mean free paths for both branches is mainly determined by the
+decay of the heavy scalar into a hard fermion and a soft collective excitation.
+We argue that these mechanisms are robust and are therefore relevant for
+non-local scenarios of baryogenesis either in the Standard Model or extensions
+thereof.",9902218v2
+2004-11-26,Open quantum systems,"The damping of the harmonic oscillator is studied in the framework of the
+Lindblad theory for open quantum systems. A generalization of the fundamental
+constraints on quantum mechanical diffusion coefficients which appear in the
+master equation for the damped quantum oscillator is presented; the
+Schr\""odinger, Heisenberg and Weyl-Wigner-Moyal representations of the Lindblad
+equation are given explicitly. On the basis of these representations it is
+shown that various master equations for the damped quantum oscillator used in
+the literature are particular cases of the Lindblad equation and that not all
+of these equations are satisfying the constraints on quantum mechanical
+diffusion coefficients. The master equation is transformed into Fokker-Planck
+equations for quasiprobability distributions and a comparative study is made
+for the Glauber $P$ representation, the antinormal ordering $Q$ representation
+and the Wigner $W$ representation. The density matrix is represented via a
+generating function, which is obtained by solving a time-dependent linear
+partial differential equation derived from the master equation. The damped
+harmonic oscillator is applied for the description of the charge equilibration
+mode observed in deep inelastic reactions. For a system consisting of two
+harmonic oscillators the time dependence of expectation values, Wigner function
+and Weyl operator are obtained and discussed. In addition models for the
+damping of the angular momentum are studied. Using this theory to the quantum
+tunneling through the nuclear barrier, besides Gamow's transitions with energy
+conservation, additional transitions with energy loss, are found. When this
+theory is used to the resonant atom-field interaction, new optical equations
+describing the coupling through the environment are obtained.",0411189v1
+2015-04-16,Attenuation of short strongly nonlinear stress pulses in dissipative granular chains,"Attenuation of short, strongly nonlinear stress pulses in chains of spheres
+and cylinders was investigated experimentally and numerically for two ratios of
+their masses keeping their contacts identical. The chain with mass ratio 0.98
+supports solitary waves and another one (with mass ratio 0.55) supports
+nonstationary pulses which preserve their identity only on relatively short
+distances, but attenuate on longer distances because of radiation of small
+amplitude tails generated by oscillating small mass particles. Pulse
+attenuation in experiments in the chain with mass ratio 0.55 was faster at the
+same number of the particles from the entrance than in the chain with mass
+ratio 0.98. It is in quantitative agreement with results of numerical
+calculations with effective damping coefficient 6 kg/s. This level of damping
+was critical for eliminating the gap openings between particles in the system
+with mass ratio 0.55 present at lower or no damping. However with increase of
+dissipation numerical results show that the chain with mass ratio 0.98 provides
+faster attenuation than chain with mass ratio 0.55 due to the fact that the
+former system supports the narrower pulse with the larger difference between
+velocities of neighboring particles. The investigated chains demonstrated
+different wave structure at zero dissipation and at intermediate damping
+coefficients and the similar behavior at large damping.",1504.04344v1
+2023-03-15,Blow-up and decay for a class of variable coefficient wave equation with nonlinear damping and logarithmic source,"In this paper, we consider the long time behavior for the solution of a class
+of variable coefficient wave equation with nonlinear damping and logarithmic
+source. The existence and uniqueness of local weak solution can be obtained by
+using the Galerkin method and contraction mapping principle. However, the long
+time behavior of the solution is usually complicated and it depends on the
+balance mechanism between the damping and source terms. When the damping
+exponent $(p+1)$ (see assumption (H3)) is greater than the source term exponent
+$(q-1)$ (see equation (1.1)), namely, $p+2>q$, we obtain the global existence
+and accurate decay rates of the energy for the weak solutions with any initial
+data. Moreover, whether the weak solution exists globally or blows up in finite
+time, it is closely related to the initial data. In the framework of modified
+potential well theory, we construct the stable and unstable sets (see (2.8))
+for the initial data. For the initial data belonging to the stable set, we
+prove that the weak solution exists globally and has similar decay rates as the
+previous results. For $p+2<q$ and the initial data belonging to the unstable
+set, we prove that the weak solution blows up in finite time for a little
+special damping $g(u_{t})=|u_{t}|^{p}u_{t}$.",2303.08629v1
+2023-07-12,Exponential stability of damped Euler-Bernoulli beam controlled by boundary springs and dampers,"In this paper, the vibration model of an elastic beam, governed by the damped
+Euler-Bernoulli equation
+$\rho(x)u_{tt}+\mu(x)u_{t}$$+\left(r(x)u_{xx}\right)_{xx}=0$, subject to the
+clamped boundary conditions $u(0,t)=u_x(0,t)=0$ at $x=0$, and the boundary
+conditions $\left(-r(x)u_{xx}\right)_{x=\ell}=k_r u_x(\ell,t)+k_a
+u_{xt}(\ell,t)$, $\left(-\left(r(x)u_{xx}\right)_{x}\right )_{x=\ell}$$=- k_d
+u(\ell,t)-k_v u_{t}(\ell,t)$ at $x=\ell$, is analyzed. The boundary conditions
+at $x=\ell$ correspond to linear combinations of damping moments caused by
+rotation and angular velocity and also, of forces caused by displacement and
+velocity, respectively. The system stability analysis based on well-known
+Lyapunov approach is developed. Under the natural assumptions guaranteeing the
+existence of a regular weak solution, uniform exponential decay estimate for
+the energy of the system is derived. The decay rate constant in this estimate
+depends only on the physical and geometric parameters of the beam, including
+the viscous external damping coefficient $\mu(x) \ge 0$, and the boundary
+springs $k_r,k_d \ge 0$ and dampers $k_a,k_v \ge 0$. Some numerical examples
+are given to illustrate the role of the damping coefficient and the boundary
+dampers.",2307.06170v2
+2017-04-12,The gradient condition and the contribution of the dynamical part of Green-Kubo formula to the diffusion coefficient,"In the diffusive hydrodynamic limit for a symmetric interacting particle
+system (such as the exclusion process, the zero range process, the stochastic
+Ginzburg-Landau model, the energy exchange model), a possibly non-linear
+diffusion equation is derived as the hydrodynamic equation. The bulk diffusion
+coefficient of the limiting equation is given by Green-Kubo formula and it can
+be characterized by a variational formula. In the case the system satisfies the
+gradient condition, the variational problem is explicitly solved and the
+diffusion coefficient is given from the Green-Kubo formula through a static
+average only. In other words, the contribution of the dynamical part of
+Green-Kubo formula is 0. In this paper, we consider the converse, namely if the
+contribution of the dynamical part of Green-Kubo formula is 0, does it imply
+the system satisfies the gradient condition or not. We show that if the
+equilibrium measure {\mu} is product and {L^2} space of its single site
+marginal is separable, then the converse also holds. As an application of the
+result, we consider a class of stochastic models for energy transport studied
+by Gaspard and Gilbert in [1, 2], where the exact problem is discussed for this
+specific model.",1704.03745v2
+2010-06-25,Perturbations of Mathieu equations with parametric excitation of large period,"We consider a linear differential system of Mathieu equations with periodic
+coefficients over periodic closed orbits and we prove that, arbitrarily close
+to this system, there is a linear differential system of Hamiltonian damped
+Mathieu equations with periodic coefficients over periodic closed orbits such
+that, all but a finite number of closed periodic coefficients, have unstable
+solutions. The perturbations will be peformed in the periodic coefficients.",1006.5025v1
+2008-02-07,Cascade and Damping of Alfvén-Cyclotron Fluctuations: Application to Solar Wind Turbulence Spectrum,"With the diffusion approximation, we study the cascade and damping of
+Alfv\'{e}n-cyclotron fluctuations in solar plasmas numerically. Motivated by
+wave-wave couplings and nonlinear effects, we test several forms of the
+diffusion tensor. For a general locally anisotropic and inhomogeneous diffusion
+tensor in the wave vector space, the turbulence spectrum in the inertial range
+can be fitted with power-laws with the power-law index varying with the wave
+propagation direction. For several locally isotropic but inhomogeneous
+diffusion coefficients, the steady-state turbulence spectra are nearly
+isotropic in the absence of damping and can be fitted by a single power-law
+function. However, the energy flux is strongly polarized due to the
+inhomogeneity that leads to an anisotropic cascade. Including the anisotropic
+thermal damping, the turbulence spectrum cuts off at the wave numbers, where
+the damping rates become comparable to the cascade rates. The combined
+anisotropic effects of cascade and damping make this cutoff wave number
+dependent on the wave propagation direction, and the propagation direction
+integrated turbulence spectrum resembles a broken power-law, which cuts off at
+the maximum of the cutoff wave numbers or the $^4$He cyclotron frequency.
+Taking into account the Doppler effects, the model can naturally reproduce the
+broken power-law wave spectra observed in the solar wind and predicts that a
+higher break frequency is aways accompanied with a greater spectral index
+change that may be caused by the increase of the Alfv\'{e}n Mach number, the
+reciprocal of the plasma beta, and/or the angle between the solar wind velocity
+and the mean magnetic field. These predictions can be tested by future
+observations.",0802.0910v1
+2023-10-07,OEDG: Oscillation-eliminating discontinuous Galerkin method for hyperbolic conservation laws,"Controlling spurious oscillations is crucial for designing reliable numerical
+schemes for hyperbolic conservation laws. This paper proposes a novel, robust,
+and efficient oscillation-eliminating discontinuous Galerkin (OEDG) method on
+general meshes, motivated by the damping technique in [Lu, Liu, and Shu, SIAM
+J. Numer. Anal., 59:1299-1324, 2021]. The OEDG method incorporates an OE
+procedure after each Runge-Kutta stage, devised by alternately evolving
+conventional semidiscrete DG scheme and a damping equation. A novel damping
+operator is carefully designed to possess scale-invariant and
+evolution-invariant properties. We rigorously prove optimal error estimates of
+the fully discrete OEDG method for linear scalar conservation laws. This might
+be the first generic fully-discrete error estimates for nonlinear DG schemes
+with automatic oscillation control mechanism. The OEDG method exhibits many
+notable advantages. It effectively eliminates spurious oscillations for
+challenging problems across various scales and wave speeds, without
+problem-specific parameters. It obviates the need for characteristic
+decomposition in hyperbolic systems. It retains key properties of conventional
+DG method, such as conservation, optimal convergence rates, and
+superconvergence. Moreover, it remains stable under normal CFL condition. The
+OE procedure is non-intrusive, facilitating integration into existing DG codes
+as an independent module. Its implementation is easy and efficient, involving
+only simple multiplications of modal coefficients by scalars. The OEDG approach
+provides new insights into the damping mechanism for oscillation control. It
+reveals the role of damping operator as a modal filter and establishes close
+relations between the damping and spectral viscosity techniques. Extensive
+numerical results confirm the theoretical analysis and validate the
+effectiveness and advantages of the OEDG method.",2310.04807v1
+2018-08-08,Analysis of quasi-Monte Carlo methods for elliptic eigenvalue problems with stochastic coefficients,"We consider the forward problem of uncertainty quantification for the
+generalised Dirichlet eigenvalue problem for a coercive second order partial
+differential operator with random coefficients, motivated by problems in
+structural mechanics, photonic crystals and neutron diffusion. The PDE
+coefficients are assumed to be uniformly bounded random fields, represented as
+infinite series parametrised by uniformly distributed i.i.d. random variables.
+The expectation of the fundamental eigenvalue of this problem is computed by
+(a) truncating the infinite series which define the coefficients; (b)
+approximating the resulting truncated problem using lowest order conforming
+finite elements and a sparse matrix eigenvalue solver; and (c) approximating
+the resulting finite (but high dimensional) integral by a randomly shifted
+quasi-Monte Carlo lattice rule, with specially chosen generating vector. We
+prove error estimates for the combined error, which depend on the truncation
+dimension $s$, the finite element mesh diameter $h$, and the number of
+quasi-Monte Carlo samples $N$. Under suitable regularity assumptions, our
+bounds are of the particular form $\mathcal{O}(h^2+N^{-1+\delta})$, where
+$\delta>0$ is arbitrary and the hidden constant is independent of the
+truncation dimension, which needs to grow as $h\to 0$ and $N\to\infty$.
+Although the eigenvalue problem is nonlinear, which means it is generally
+considered harder than the analogous source problem, in almost all cases we
+obtain error bounds that converge at the same rate as the corresponding rate
+for the source problem. The proof involves a detailed study of the regularity
+of the fundamental eigenvalue as a function of the random parameters. As a key
+intermediate result in the analysis, we prove that the spectral gap (between
+the fundamental and the second eigenvalues) is uniformly positive over all
+realisations of the random problem.",1808.02639v3
+2021-01-22,Measurements and analysis of response function of cold atoms in optical molasses,"We report our experimental measurements and theoretical analysis of the
+position response function of a cloud of cold atoms residing in the viscous
+medium of an optical molasses and confined by a magneto-optical trap (MOT). We
+measure the position response function by applying a transient homogeneous
+magnetic field as a perturbing force. We observe a transition from a damped
+oscillatory motion to an over-damped relaxation, stemming from a competition
+between the viscous drag provided by the optical molasses and the restoring
+force of the MOT. Our observations are in both qualitative and quantitative
+agreement with the predictions of a theoretical model based on the Langevin
+equation. As a consistency check, and as a prototype for future experiments, we
+also study the free diffusive spreading of the atomic cloud in our optical
+molasses with the confining magnetic field of the MOT turned off. We find that
+the measured value of the diffusion coefficient agrees with the value predicted
+by our Langevin model, using the damping coefficient. The damping coefficient
+was deduced from our measurements of the position response function at the same
+temperature.",2101.09118v2
+2020-12-08,Sparse Correspondence Analysis for Contingency Tables,"Since the introduction of the lasso in regression, various sparse methods
+have been developed in an unsupervised context like sparse principal component
+analysis (s-PCA), sparse canonical correlation analysis (s-CCA) and sparse
+singular value decomposition (s-SVD). These sparse methods combine feature
+selection and dimension reduction. One advantage of s-PCA is to simplify the
+interpretation of the (pseudo) principal components since each one is expressed
+as a linear combination of a small number of variables. The disadvantages lie
+on the one hand in the difficulty of choosing the number of non-zero
+coefficients in the absence of a well established criterion and on the other
+hand in the loss of orthogonality for the components and/or the loadings. In
+this paper we propose sparse variants of correspondence analysis (CA)for large
+contingency tables like documents-terms matrices used in text mining, together
+with pPMD, a deation technique derived from projected deflation in s-PCA. We
+use the fact that CA is a double weighted PCA (for rows and columns) or a
+weighted SVD, as well as a canonical correlation analysis of indicator
+variables. Applying s-CCA or s-SVD allows to sparsify both rows and columns
+weights. The user may tune the level of sparsity of rows and columns and
+optimize it according to some criterium, and even decide that no sparsity is
+needed for rows (or columns) by relaxing one sparsity constraint. The latter is
+equivalent to apply s-PCA to matrices of row (or column) profiles.",2012.04271v1
+1996-01-09,Relaxation of Collective Excitations in LJ-13 Cluster,"We have performed classical molecular dynamics simulation of $Ar_{13}$
+cluster to study the behavior of collective excitations. In the solid ``phase''
+of the cluster, the collective oscillation of the monopole mode can be well
+fitted to a damped harmonic oscillator. The parameters of the equivalent damped
+harmonic oscillator-- the damping coefficient, spring constant, time period of
+oscillation and the mass of the oscillator -- all show a sharp change in
+behavior at a kinetic temperature of about $7.0^oK$. This marks yet another
+characteristic temperature of the system, a temperature $T_s$ below which
+collective excitations are very stable, and at higher temperatures the single
+particle excitations cause the damping of the collective oscillations. We argue
+that so long as the cluster remains confined within the global potential energy
+minimum the collective excitations do not decay; and once the cluster comes out
+of this well, the local potential energy minima pockets act as single particle
+excitation channels in destroying the collective motion. The effect is manifest
+in almost all the physical observables of the cluster.",9601026v2
+2003-09-11,Frequency and damping of hydrodynamic modes in a trapped Bose-condensed gas,"Recently it was shown that the Landau-Khalatnikov two-fluid hydrodynamics
+describes the collision-dominated region of a trapped Bose condensate
+interacting with a thermal cloud. We use these equations to discuss the low
+frequency hydrodynamic collective modes in a trapped Bose gas at finite
+temperatures. We derive a variational expressions based on these equations for
+both the frequency and damping of collective modes. A new feature is our use of
+frequency-dependent transport coefficients, which produce a natural cutoff by
+eliminating the collisionless low-density tail of the thermal cloud. Above the
+superfluid transition, our expression for the damping in trapped inhomogeneous
+gases is analogous to the result first obtained by Landau and Lifshitz for
+uniform classical fluids. We also use the moment method to discuss the
+crossover from the collisionless to the hydrodynamic region. Recent data for
+the monopole-quadrupole mode in the hydrodynamic region of a trapped gas of
+metastable $^4$He is discussed. We also present calculations for the damping of
+the analogous $m=0$ monopole-quadrupole condensate mode in the superfluid
+phase.",0309269v1
+2012-01-31,Parametric amplification and self-oscillation in a nanotube mechanical resonator,"A hallmark of mechanical resonators made from a single nanotube is that the
+resonance frequency can be widely tuned. Here, we take advantage of this
+property to realize parametric amplification and self-oscillation. The gain of
+the parametric amplification can be as high as 18.2 dB and tends to saturate at
+high parametric pumping due to nonlinear damping. These measurements allow us
+to determine the coefficient of the linear damping force. The corresponding
+damping rate is lower than the one obtained from the lineshape of the resonance
+(without pumping), supporting the recently reported scenario that describes
+damping in nanotube resonators by a nonlinear force. The possibility to combine
+nanotube resonant mechanics and parametric amplification holds promise for
+future ultra-low force sensing experiments.",1201.6557v1
+2012-07-12,Damping of phase fluctuations in superfluid Bose gases,"Using Popov's hydrodynamic approach we derive an effective Euclidean action
+for the long-wavelength phase fluctuations of superfluid Bose gases in D
+dimensions. We then use this action to calculate the damping of phase
+fluctuations at zero temperature as a function of D. For D >1 and wavevectors |
+k | << 2 mc (where m is the mass of the bosons and c is the sound velocity) we
+find that the damping in units of the phonon energy E_k = c | k | is to leading
+order gamma_k / E_k = A_D (k_0^D / 2 pi rho) (| k | / k_0)^{2 D -2}, where rho
+is the boson density and k_0 =2 mc is the inverse healing length. For D -> 1
+the numerical coefficient A_D vanishes and the damping is proportional to an
+additional power of |k | /k_0; a self-consistent calculation yields in this
+case gamma_k / E_k = 1.32 (k_0 / 2 pi rho)^{1/2} |k | / k_0. In one dimension,
+we also calculate the entire spectral function of phase fluctuations.",1207.3002v3
+2014-10-13,Relaxation damping in oscillating contacts,"If a contact of two purely elastic bodies with no sliding (infinite
+coefficient of friction) is subjected to superimposed oscillations in the
+normal and tangential directions, then a specific damping appears, that is not
+dependent on friction or dissipation in the material. We call this effect
+""relaxation damping"". The rate of energy dissipation due to relaxation damping
+is calculated in a closed analytic form for arbitrary axially-symmetric
+contacts. In the case of equal frequency of normal and tangential oscillations,
+the dissipated energy per cycle is proportional to the square of the amplitude
+of tangential oscillation and to the absolute value of the amplitude of normal
+oscillation, and is dependent on the phase shift between both oscillations. In
+the case of low frequency tangential motion with superimposed high frequency
+normal oscillations, the system acts as a tunable linear damper. Generalization
+of the results for macroscopically planar, randomly rough surfaces is
+discussed.",1410.3238v1
+2016-04-29,Nonlinear Landau damping of wave envelopes in a quantum plasma,"The nonlinear theory of Landau damping of electrostatic wave envelopes (WEs)
+is revisited in a quantum electron-positron (EP) pair plasma. Starting from a
+Wigner-Moyal equation coupled to the Poisson equation and applying the multiple
+scale technique, we derive a nonlinear Schr{\""o}dinger (NLS) equation which
+governs the evolution of electrostatic WEs. It is shown that the coefficients
+of the NLS equation, including the nonlocal nonlinear term, which appears due
+to the resonant particles having group velocity of the WEs, are significantly
+modified by the particle dispersion. The effects of the quantum parameter $H$
+(the ratio of the plasmon energy to the thermal energy densities), associated
+with the particle dispersion, are examined on the Landau damping rate of
+carrier waves, as well as on the modulational instability of WEs. It is found
+that the Landau damping rate and the decay rate of the solitary wave amplitude
+are greatly reduced compared to their classical values $(H=0)$.",1604.08751v4
+2017-06-11,Absorbing boundary layers for spin wave micromagnetics,"Micromagnetic simulations are used to investigate the effects of different
+absorbing boundary layers (ABLs) on spin waves (SWs) reflected from the edges
+of a magnetic nano-structure. We define the conditions that a suitable ABL must
+fulfill and compare the performance of abrupt, linear, polynomial and tan
+hyperbolic damping profiles in the ABL. We first consider normal incidence in a
+permalloy stripe and propose a transmission line model to quantify reflections
+and calculate the loss introduced into the stripe due to the ABL. We find that
+a parabolic damping profile absorbs the SW energy efficiently and has a low
+reflection coefficient, thus performing much better than the commonly used
+abrupt damping profile. We then investigated SWs that are obliquely incident at
+26.6, 45 and 63.4 degrees on the edge of a yttrium-iron-garnet film. The
+parabolic damping profile again performs efficiently by showing a high SW
+energy transfer to the ABL and a low reflected SW amplitude.",1706.03325v1
+2017-10-17,Entropic uncertainty relation under quantum channels with memory,"Recently, Xu et al. [Phys. Rev. A 86, 012113(2012)] explored the behavior of
+the entropic uncertainty relation under the influence of local unital and
+nonunital noisy channels for a class of Bell-diagonal states. We here reform
+their results and investigate the entropic uncertainty relation under the
+influence of unital and nonunital noisy channels with memory. Different types
+of noisy channels with memory, such as amplitude damping channel(nonunitary),
+phase-damping and depolarizing channels(unitary) have been taken into account.
+Some analytical or numerical results are presented. The effect of channels with
+memory on dynamics of the entropic uncertainties (or their lower bounds) has
+been discussed in detail. Compare with previous results, our results show that,
+the entropic uncertainties (or their lower bounds) subjecting to amplitude
+damping channel with memory will be reduced at first and then be lifted with
+the memory coefficient of channel $\mu$ increasing, however they will be only
+reduced under phase-damping and depolarizing channels with memory. Especially,
+in the limit of $\mu\rightarrow1$, the entropic uncertainties (or their lower
+bounds) could be well protected and immune to decoherence of channle. Moreover,
+the mechanism behind these phenomena are also explored by using the purity of
+state.",1710.06344v1
+2018-04-15,Reevaluation of radiation reaction and consequences for light-matter interactions at the nanoscale,"In the context of electromagnetism and nonlinear optical interactions damping
+is generally introduced as a phenomenological, viscous term that dissipates
+energy, proportional to the temporal derivative of the polarization. Here, we
+follow the radiation reaction method presented in [G. W. Ford and R. F.
+O'Connell, Phys. Lett. A, 157, 217 (1991)], which applies to non-relativistic
+electrons of finite size, to introduce an explicit reaction force in the
+Newtonian equation of motion, and derive a hydrodynamic equation that offers
+new insight on the influence of damping in generic plasmas, metal-based and/or
+dielectric structures. In these settings, we find new damping-dependent linear
+and nonlinear source terms that suggest the damping coefficient is proportional
+to the local charge density, and nonlocal contributions that stem from the
+spatial derivative of the magnetic field and discuss the conditions that could
+modify both linear and nonlinear electromagnetic responses.",1804.05369v1
+2018-12-04,Atmospheric oscillations provide simultaneous measurement of neutron star mass and radius,"Neutron stars with near-Eddington observable luminosities were shown to
+harbor levitating atmospheres, suspended above their surface. We report a new
+method to simultaneously measure the mass and radius of a neutron star based on
+oscillations of such atmospheres. In this paper, we present an analytic
+derivation of a family of relativistic, oscillatory, spherically symmetric
+eigenmodes of the optically and geometrically thin levitating atmospheres,
+including the damping effects induced by the radiation drag. We discover
+characteristic maxima in the frequencies of the damped oscillations and show
+that using the frequency maxima, one can estimate mass and radius of the
+neutron star, given the observed frequency and the corresponding luminosity of
+the star during the X-ray burst. Thus, our model provides a new way to probe
+the stellar parameters. We also show that the ratio of any two undamped
+eigenfrequencies depends only on the adiabatic index of the atmosphere, while
+for the damped eigenfrequencies, this ratio varies with the luminosity. The
+damping coefficient is independent of the mode number of the oscillations.
+Signatures of these atmospheres' dynamics will be reflected in the source's
+X-ray light curves.",1812.01299v2
+2019-01-13,Nonexistence of global solutions for a weakly coupled system of semilinear damped wave equations in the scattering case with mixed nonlinear terms,"In this paper we consider the blow-up of solutions to a weakly coupled system
+of semilinear damped wave equations in the scattering case with nonlinearities
+of mixed type, namely, in one equation a power nonlinearity and in the other a
+semilinear term of derivative type. The proof of the blow-up results is based
+on an iteration argument. As expected, due to the assumptions on the
+coefficients of the damping terms, we find as critical curve in the p-q plane
+for the pair of exponents (p,q) in the nonlinear terms the same one found by
+Hidano-Yokoyama and, recently, by Ikeda-Sobajima-Wakasa for the weakly coupled
+system of semilinear wave equations with the same kind of nonlinearities. In
+the critical and not-damped case we provide a different approach from the test
+function method applied by Ikeda-Sobajima-Wakasa to prove the blow-up of the
+solution on the critical curve, improving in some cases the upper bound
+estimate for the lifespan. More precisely, we combine an iteration argument
+with the so-called slicing method to show the blow-up dynamic of a weighted
+version of the functionals used in the subcritical case.",1901.04038v1
+2019-03-03,Spin wave damping in periodic and quasiperiodic magnonic structures,"We investigated the lifetime of spin wave eigenmodes in periodic and
+quasiperiodic sequences of Py and Co wires. Those materials differ
+significantly in damping coefficients, therefore, the spatial distribution of
+the mode amplitude within the structure is important for the lifetime of
+collective spin wave excitations. Modes of the lower frequencies prefer to
+concentrate in Py wires, because of the lower FMR frequency for this material.
+This inhomogeneous distribution of amplitude of modes (with lower amplitude in
+material of higher damping and with higher amplitude in material of lower
+damping) is preferable for extending the lifetime of the collective excitations
+beyond the volume average of lifetimes for solid materials. We established the
+relation between the profile of the mode and its lifetime for periodic and
+quasiperiodic structures. We performed also the comparative studies in order to
+find the differences resulting from complexity of the structure and enhancement
+of localization in quasiperiodic system on the lifetime of spin waves.",1903.00856v1
+2019-05-23,Strauss exponent for semilinear wave equations with scattering space dependent damping,"It is believed or conjectured that the semilinear wave equations with
+scattering space dependent damping admit the Strauss critical exponent, see
+Ikehata-Todorova-Yordanov \cite{ITY}(the bottom in page 2) and
+Nishihara-Sobajima-Wakasugi \cite{N2}(conjecture iii in page 4). In this work,
+we are devoted to showing the conjecture is true at least when the decay rate
+of the space dependent variable coefficients before the damping is larger than
+2. Also, if the nonlinear term depends only on the derivative of the solution,
+we may prove the upper bound of the lifespan is the same as that of the
+solution of the corresponding problem without damping. This shows in another
+way the \lq\lq hyperbolicity"" of the equation.",1905.09445v2
+2020-06-09,Logarithmic decay for damped hypoelliptic wave and Schr{ö}dinger equations,"We consider damped wave (resp. Schr{\""o}dinger and plate) equations driven by
+a hypoelliptic ""sum of squares"" operator L on a compact manifold and a damping
+function b(x). We assume the Chow-Rashevski-H{\""o}rmander condition at rank k
+(at most k Lie brackets needed to span the tangent space) together with
+analyticity of M and the coefficients of L. We prove decay of the energy at
+rate $log(t)^{-1/k}$ (resp. $log(t)^{-2/k}$ ) for data in the domain of the
+generator of the associated group. We show that this decay is optimal on a
+family of Grushin-type operators. This result follows from a perturbative
+argument (of independent interest) showing, in a general abstract setting, that
+quantitative approximate observability/controllability results for wave-type
+equations imply a priori decay rates for associated damped wave,
+Schr{\""o}dinger and plate equations. The adapted quantitative approximate
+observability/controllability theorem for hypoelliptic waves is obtained by the
+authors in [LL19, LL17].",2006.05122v1
+2020-11-15,A Random Matrix Theory Approach to Damping in Deep Learning,"We conjecture that the inherent difference in generalisation between adaptive
+and non-adaptive gradient methods in deep learning stems from the increased
+estimation noise in the flattest directions of the true loss surface. We
+demonstrate that typical schedules used for adaptive methods (with low
+numerical stability or damping constants) serve to bias relative movement
+towards flat directions relative to sharp directions, effectively amplifying
+the noise-to-signal ratio and harming generalisation. We further demonstrate
+that the numerical damping constant used in these methods can be decomposed
+into a learning rate reduction and linear shrinkage of the estimated curvature
+matrix. We then demonstrate significant generalisation improvements by
+increasing the shrinkage coefficient, closing the generalisation gap entirely
+in both logistic regression and several deep neural network experiments.
+Extending this line further, we develop a novel random matrix theory based
+damping learner for second order optimiser inspired by linear shrinkage
+estimation. We experimentally demonstrate our learner to be very insensitive to
+the initialised value and to allow for extremely fast convergence in
+conjunction with continued stable training and competitive generalisation.",2011.08181v5
+2021-04-09,"Nonexistence result for the generalized Tricomi equation with the scale-invariant damping, mass term and time derivative nonlinearity","In this article, we consider the damped wave equation in the
+\textit{scale-invariant case} with time-dependent speed of propagation, mass
+term and time derivative nonlinearity. More precisely, we study the blow-up of
+the solutions to the following equation: $$ (E) \quad u_{tt}-t^{2m}\Delta
+u+\frac{\mu}{t}u_t+\frac{\nu^2}{t^2}u=|u_t|^p, \quad \mbox{in}\
+\mathbb{R}^N\times[1,\infty), $$ that we associate with small initial data.
+Assuming some assumptions on the mass and damping coefficients, $\nu$ and
+$\mu>0$, respectively, that the blow-up region and the lifespan bound of the
+solution of $(E)$ remain the same as the ones obtained for the case without
+mass, {\it i.e.} $\nu=0$ in $(E)$. The latter case constitutes, in fact, a
+shift of the dimension $N$ by $\frac{\mu}{1+m}$ compared to the problem without
+damping and mass. Finally, we think that the new bound for $p$ is a serious
+candidate to the critical exponent which characterizes the threshold between
+the blow-up and the global existence regions.",2104.04393v2
+2021-07-29,A N-dimensional elastic\viscoelastic transmission problem with Kelvin-Voigt damping and non smooth coefficient at the interface,"We investigate the stabilization of a multidimensional system of coupled wave
+equations with only one Kelvin Voigt damping. Using a unique continuation
+result based on a Carleman estimate and a general criteria of Arendt Batty, we
+prove the strong stability of the system in the absence of the compactness of
+the resolvent without any geometric condition. Then, using a spectral analysis,
+we prove the non uniform stability of the system. Further, using frequency
+domain approach combined with a multiplier technique, we establish some
+polynomial stability results by considering different geometric conditions on
+the coupling and damping domains. In addition, we establish two polynomial
+energy decay rates of the system on a square domain where the damping and the
+coupling are localized in a vertical strip.",2107.13785v1
+2021-12-27,Trajectory attractors for 3D damped Euler equations and their approximation,"We study the global attractors for the damped 3D Euler--Bardina equations
+with the regularization parameter $\alpha>0$ and Ekman damping coefficient
+$\gamma>0$ endowed with periodic boundary conditions as well as their damped
+Euler limit $\alpha\to0$. We prove that despite the possible non-uniqueness of
+solutions of the limit Euler system and even the non-existence of such
+solutions in the distributional sense, the limit dynamics of the corresponding
+dissipative solutions introduced by P.\,Lions can be described in terms of
+attractors of the properly constructed trajectory dynamical system. Moreover,
+the convergence of the attractors $\Cal A(\alpha)$ of the regularized system to
+the limit trajectory attractor $\Cal A(0)$ as $\alpha\to0$ is also established
+in terms of the upper semicontinuity in the properly defined functional space.",2112.13691v1
+2023-01-02,Fast convex optimization via closed-loop time scaling of gradient dynamics,"In a Hilbert setting, for convex differentiable optimization, we develop a
+general framework for adaptive accelerated gradient methods. They are based on
+damped inertial dynamics where the coefficients are designed in a closed-loop
+way. Specifically, the damping is a feedback control of the velocity, or of the
+gradient of the objective function. For this, we develop a closed-loop version
+of the time scaling and averaging technique introduced by the authors. We thus
+obtain autonomous inertial dynamics which involve vanishing viscous damping and
+implicit Hessian driven damping. By simply using the convergence rates for the
+continuous steepest descent and Jensen's inequality, without the need for
+further Lyapunov analysis, we show that the trajectories have several
+remarkable properties at once: they ensure fast convergence of values, fast
+convergence of the gradients towards zero, and they converge to optimal
+solutions. Our approach leads to parallel algorithmic results, that we study in
+the case of proximal algorithms. These are among the very first general results
+of this type obtained using autonomous dynamics.",2301.00701v1
+2023-04-22,Video analysis of the damped oscillations of Pohl's pendulum,"In this paper problems that arose with the introduction of distance learning
+in physics at the Technical University of Sofia due to the COVID-19 pandemic
+and the imposition of video recording of laboratory exercises are indicated. It
+was found that the video for the ''Damped Mechanical Oscillations'' exercise
+provides enough information for a more detailed and in-depth analysis of the
+studied phenomenon compared to the standard way of capturing the data. The
+Video Editor program was used to view the video frame by frame and statistical
+processing - non-linear regression - was performed with the recorded data. The
+laboratory results are compared with the theoretical function, the parameters
+of which are optimized as a result of the specified processing. A theoretical
+model of the damped oscillation is described and the dependence of the damping
+coefficient on the current through the electromagnetic brake is theoretically
+investigated.",2304.11390v1
+2023-11-23,"Friction of a driven chain: Role of momentum conservation, Goldstone and radiation modes","We analytically study friction and dissipation of a driven bead in a 1D
+harmonic chain, and analyze the role of internal damping mechanism as well as
+chain length. Specifically, we investigate Dissipative Particle Dynamics and
+Langevin Dynamics, as paradigmatic examples that do and do not display
+translational symmetry, with distinct results: For identical parameters, the
+friction forces can differ by many orders of magnitude. For slow driving, a
+Goldstone mode traverses the entire system, resulting in friction of the driven
+bead that grows arbitrarily large (Langevin) or gets arbitrarily small
+(Dissipative Particle Dynamics) with system size. For a long chain, the
+friction for DPD is shown to be bound, while it shows a singularity (i.e. can
+be arbitrarily large) for Langevin damping. For long underdamped chains, a
+radiation mode is recovered in either case, with friction independent of
+damping mechanism. For medium length chains, the chain shows the expected
+resonant behavior. At the resonance, friction is non-analytic in damping
+parameter $\gamma$, depending on it as $\gamma^{-1}$. Generally, no zero
+frequency bulk friction coefficient can be determined, as the limits of small
+frequency and infinite chain length do not commute, and we discuss the regimes
+where ""simple"" macroscopic friction occurs.",2311.14075v1
+2023-12-14,Smoluchowski-Kramers diffusion approximation for systems of stochastic damped wave equations with non-constant friction,"We consider systems of damped wave equations with a state-dependent damping
+coefficient and perturbed by a Gaussian multiplicative noise. Initially, we
+investigate their well-posedness, under quite general conditions on the
+friction. Subsequently, we study the validity of the so-called
+Smoluchowski-Kramers diffusion approximation. We show that, under more
+stringent conditions on the friction, in the small-mass limit the solution of
+the system of stochastic damped wave equations converges to the solution of a
+system of stochastic quasi-linear parabolic equations. In this convergence, an
+additional drift emerges as a result of the interaction between the noise and
+the state-dependent friction. The identification of this limit is achieved by
+using a suitable generalization of the classical method of perturbed test
+functions, tailored to the current infinite dimensional setting.",2312.08925v1
+2024-03-25,Radiation damping of a Rayleigh scatterer illuminated by a plane wave,"We investigate the radiation damping experienced by a dielectric spherical
+particle when it is illuminated by an electromagnetic plane wave within the
+Rayleigh regime. We derive the equivalent electric dipole of the moving
+particle and subsequently calculate the electromagnetic force acting on it from
+two different approaches. In the first approach, we calculate the force from
+the integration of stress tensor and field momentum. In the second one, we
+calculate the force directly from the integration of the force density. Our
+derivations reveal that the damping coefficient is equal to $6P_{scat}/mc^2$
+along the propagation direction, whereas it is $P_{scat}/mc^2$ along
+perpendicular directions. Here, $P_{scat}$ denotes the power scattered by the
+particle, and $mc^2$ represents the particle's mass energy. The radiation
+damping derived in this study sets upper limits on the quality factor of
+optically levitated objects and ensures the existence of a steady-state
+solution of the particle's dynamics.",2403.16618v1
+2022-06-30,Effect of a viscous fluid shell on the propagation of gravitational waves,"In this paper we show that there are circumstances in which the damping of
+gravitational waves (GWs) propagating through a viscous fluid can be highly
+significant; in particular, this applies to Core Collapse Supernovae (CCSNe).
+In previous work, we used linearized perturbations on a fixed background within
+the Bondi-Sachs formalism, to determine the effect of a dust shell on GW
+propagation. Here, we start with the (previously found) velocity field of the
+matter, and use it to determine the shear tensor of the fluid flow. Then, for a
+viscous fluid, the energy dissipated is calculated, leading to an equation for
+GW damping. It is found that the damping effect agrees with previous results
+when the wavelength $\lambda$ is much smaller than the radius $r_i$ of the
+matter shell; but if $\lambda\gg r_i$, then the damping effect is greatly
+increased.
+  Next, the paper discusses an astrophysical application, CCSNe. There are
+several different physical processes that generate GWs, and many models have
+been presented in the literature. The damping effect thus needs to be evaluated
+with each of the parameters $\lambda,r_i$ and the coefficient of shear
+viscosity $\eta$, having a range of values. It is found that in most cases
+there will be significant damping, and in some cases that it is almost
+complete.
+  We also consider the effect of viscous damping on primordial gravitational
+waves (pGWs) generated during inflation in the early Universe. Two cases are
+investigated where the wavelength is either much shorter than the shell radii
+or much longer; we find that there are conditions that will produce significant
+damping, to the extent that the waves would not be detectable.",2206.15103v2
+2005-07-15,A Theory of Physical Quantum Computation: The Quantum Computer Condition,"In this paper we present a new unified theoretical framework that describes
+the full dynamics of quantum computation. Our formulation allows any questions
+pertaining to the physical behavior of a quantum computer to be framed, and in
+principle, answered. We refer to the central organizing principle developed in
+this paper, on which our theoretical structure is based, as the *Quantum
+Computer Condition* (QCC), a rigorous mathematical statement that connects the
+irreversible dynamics of the quantum computing machine, with the reversible
+operations that comprise the quantum computation intended to be carried out by
+the quantum computing machine. Armed with the QCC, we derive a powerful result
+that we call the *Encoding No-Go Theorem*. This theorem gives a precise
+mathematical statement of the conditions under which fault-tolerant quantum
+computation becomes impossible in the presence of dissipation and/or
+decoherence. In connection with this theorem, we explicitly calculate a
+universal critical damping value for fault-tolerant quantum computation. In
+addition we show that the recently-discovered approach to quantum error
+correction known as ""operator quantum error-correction"" (OQEC) is a special
+case of our more general formulation. Our approach furnishes what we will refer
+to as ""operator quantum fault-tolerance"" (OQFT). In particular, we show how the
+QCC allows one to derive error thresholds for fault tolerance in a completely
+general context. We prove the existence of solutions to a class of
+time-dependent generalizations of the Lindblad equation. Using the QCC, we also
+show that the seemingly different circuit, graph- (including cluster-) state,
+and adiabatic paradigms for quantum computing are in fact all manifestations of
+a single, universal paradigm for all physical quantum computation.",0507141v2
+2018-12-22,Spin dynamics of $3d$ and $4d$ impurities embedded in prototypical topological insulators,"Topological insulators are insulating bulk materials hosting conducting
+surface states. Their magnetic doping breaks time-reversal symmetry and
+generates numerous interesting effects such as dissipationless transport.
+Nonetheless, their dynamical properties are still poorly understood. Here, we
+perform a systematic investigation of transverse spin excitations of $3d$ and
+$4d$ single impurities embedded in two prototypical topological insulators
+(Bi$_2$Te$_3$ and Bi$_2$Se$_3$). The impurity-induced states within the bulk
+gap of the topological insulators are found to have a drastic impact on the
+spin excitation spectra, resulting in very high lifetimes reaching up to
+${microseconds}$. An intuitive picture of the spin dynamics is obtained by
+mapping onto a generalized Landau-Lifshitz-Gilbert phenomenological model. The
+first quantity extracted from this mapping procedure is the magnetic anisotropy
+energy, which is then compared to the one provided by the magnetic force
+theorem. This uncovers some difficulties encountered with the latter, which can
+provide erroneous results for impurities with a high density of states at the
+Fermi energy. Moreover, the Gilbert damping and nutation tensors are obtained.
+The nutation effects can lead to a non-negligible shift in the spin excitation
+resonance in the high-frequency regime. Finally, we study the impact of the
+surface state on the spin dynamics, which may be severely altered due to the
+repositioning of the impurity-induced state in comparison to the bulk case. Our
+systematic investigation of this series of magnetic impurities sheds light on
+their spin dynamics within topological insulators, with implications for
+available and future experimental studies as, for instance, on the viability of
+using such impurities for solid-state qubits.",1812.09596v1
+2016-07-27,Linear and nonlinear viscoelastic arterial wall models: application on animals,"This work deals with the viscoelasticity of the arterial wall and its
+influence on the pulse waves. We describe the viscoelasticity by a non-linear
+Kelvin-Voigt model in which the coefficients are fitted using experimental time
+series of pressure and radius measured on a sheep's arterial network. We
+obtained a good agreement between the results of the nonlinear Kelvin-Voigt
+model and the experimental measurements. We found that the viscoelastic
+relaxation time-defined by the ratio between the viscoelastic coefficient and
+the Young's modulus-is nearly constant throughout the network. Therefore, as it
+is well known that smaller arteries are stiffer, the viscoelastic coefficient
+rises when approaching the peripheral sites to compensate the rise of the
+Young's modulus, resulting in a higher damping effect. We incorporated the
+fitted viscoelastic coefficients in a nonlinear 1D fluid model to compute the
+pulse waves in the network. The damping effect of viscoelasticity on the high
+frequency waves is clear especially at the peripheral sites.",1607.07973v1
+2018-09-26,The influence of oscillations on energy estimates for damped wave models with time-dependent propagation speed and dissipation,"The aim of this paper is to derive higher order energy estimates for
+solutions to the Cauchy problem for damped wave models with time-dependent
+propagation speed and dissipation. The model of interest is \begin{equation*}
+u_{tt}-\lambda^2(t)\omega^2(t)\Delta u +\rho(t)\omega(t)u_t=0, \quad
+u(0,x)=u_0(x), \,\, u_t(0,x)=u_1(x). \end{equation*} The coefficients
+$\lambda=\lambda(t)$ and $\rho=\rho(t)$ are shape functions and
+$\omega=\omega(t)$ is an oscillating function. If $\omega(t)\equiv1$ and
+$\rho(t)u_t$ is an ""effective"" dissipation term, then $L^2-L^2$ energy
+estimates are proved in [2]. In contrast, the main goal of the present paper is
+to generalize the previous results to coefficients including an oscillating
+function in the time-dependent coefficients. We will explain how the interplay
+between the shape functions and oscillating behavior of the coefficient will
+influence energy estimates.",1809.10179v2
+2009-01-12,Nonlinear Wigner solid transport over superfluid helium under AC conditions,"Nonlinear transport properties of the two-dimensional Wigner solid of surface
+electrons on superfluid helium are studied for alternating current conditions.
+For time-averaged quantities like Fourier coefficients, the field-velocity
+characteristics are shown to be qualitatively different as compared to that
+found in the DC theory. For a spatially uniform current we found a general
+solution for the field-velocity relationship which appears to be strongly
+dependent on the current frequency. If the current frequency is much lower than
+the ripplon damping parameter, the Bragg-Cherenkov resonances which appear at
+high enough drift velocities acquire a distinctive saw-tooth shape with long
+right-side tails independent of small damping. For current frequencies which
+are close or higher than the ripplon damping coefficient, the interference of
+ripplons excited at different time intervals results in a new oscillatory (in
+drift velocity) regime of Bragg-Cherenkov scattering.",0901.1508v1
+2012-10-03,Effect of temperature and velocity on superlubricity,"We study the effects of temperature and sliding velocity on superlubricity in
+numerical simulations of the Frenkel-Kontorova model. We show that resonant
+excitations of the phonons in an incommensurate sliding body lead to an
+effective friction and to thermal equilibrium with energy distributed over the
+internal degrees of freedom. For finite temperature, the effective friction can
+be described well by a viscous damping force, with a damping coefficient that
+emerges naturally from the microscopic dynamics. This damping coefficient is a
+non-monotonic function of the sliding velocity which peaks around resonant
+velocities and increases with temperature. At low velocities, it remains finite
+and nonzero, indicating the preservation of superlubricity in the zero-velocity
+limit. Finally, we propose experimental systems in which our results could be
+verified.",1210.1124v1
+2015-04-09,"Periodic-coefficient damping estimates, and stability of large-amplitude roll waves in inclined thin film flow","A technical obstruction preventing the conclusion of nonlinear stability of
+large-Froude number roll waves of the St. Venant equations for inclined thin
+film flow is the ""slope condition"" of Johnson-Noble-Zumbrun, used to obtain
+pointwise symmetrizability of the linearized equations and thereby
+high-frequency resolvent bounds and a crucial H s nonlinear damping estimate.
+Numerically, this condition is seen to hold for Froude numbers 2 \textless{} F
+3.5, but to fail for 3.5 F. As hydraulic engineering applications typically
+involve Froude number 3 F 5, this issue is indeed relevant to practical
+considerations. Here, we show that the pointwise slope condition can be
+replaced by an averaged version which holds always, thereby completing the
+nonlinear theory in the large-F case. The analysis has potentially larger
+interest as an extension to the periodic case of a type of weighted
+""Kawashima-type"" damping estimate introduced in the asymptotically-constant
+coefficient case for the study of stability of large-amplitude viscous shock
+waves.",1504.02292v1
+2015-07-24,Effect of Landau damping on alternative ion-acoustic solitary waves in a magnetized plasma consisting of warm adiabatic ions and non-thermal electrons,"Bandyopadhyay and Das [Phys. Plasmas, 9, 465-473, 2002] have derived a
+nonlinear macroscopic evolution equation for ion acoustic wave in a magnetized
+plasma consisting of warm adiabatic ions and non-thermal electrons including
+the effect of Landau damping. In that paper they have also derived the
+corresponding nonlinear evolution equation when coefficient of the nonlinear
+term of the above mentioned macroscopic evolution equation vanishes, the
+nonlinear behaviour of the ion acoustic wave is described by a modified
+macroscopic evolution equation. But they have not considered the case when the
+coefficient is very near to zero. This is the case we consider in this paper
+and we derive the corresponding evolution equation including the effect of
+Landau damping. Finally, a solitary wave solution of this macroscopic evolution
+is obtained, whose amplitude is found to decay slowly with time.",1507.06733v1
+2017-03-28,Singularity formation for the 1D compressible Euler equation with variable damping coefficient,"In this paper, we consider some blow-up problems for the 1D Euler equation
+with time and space dependent damping. We investigate sufficient conditions on
+initial data and the rate of spatial or time-like decay of the coefficient of
+damping for the occurrence of the finite time blow-up. In particular, our
+sufficient conditions ensure that the derivative blow-up occurs in finite time
+with the solution itself and the pressure bounded. Our method is based on
+simple estimates with Riemann invariants. Furthermore, we give sharp lower and
+upper estimates of the lifespan of solutions, when initial data are small
+perturbations of constant states.",1703.09821v3
+2018-06-22,Optimal Design of Virtual Inertia and Damping Coefficients for Virtual Synchronous Machines,"Increased penetration of inverter-connected renewable energy sources (RES) in
+the power system has resulted in a decrease in available rotational inertia
+which serves as an immediate response to frequency deviation due to
+disturbances. The concept of virtual inertia has been proposed to combat this
+decrease by enabling the inverters to produce active power in response to a
+frequency deviation like a synchronous generator. In this paper, we present an
+algorithm to optimally design the inertia and damping coefficient required for
+an inverter-based virtual synchronous machine (VSM) to participate efficiently
+in the inertia response portion of primary frequency control. We design the
+objective function to explicitly trade-off between competing objectives such as
+the damping rate the the frequency nadir. Specifically, we formulate the design
+problem as a constrained and regularized H2 norm minimization problem, and
+develop an efficient gradient algorithm for this non-convex problem. This
+proposed algorithm is applied to a test case to demonstrate its performance
+against existing methods.",1806.08488v1
+2021-04-29,Nano-patterning of surfaces by ion sputtering: Numerical study of the anisotropic damped Kuramoto-Sivashinsky equation,"Nonlinear models for pattern evolution by ion beam sputtering on a material
+surface present an ongoing opportunity for new numerical simulations. A
+numerical analysis of the evolution of preexisting patterns is proposed to
+investigate surface dynamics, based on a 2D anisotropic damped
+Kuramoto-Sivashinsky equation, with periodic boundary conditions. A
+finite-difference semi-implicit time splitting scheme is employed on the
+discretization of the governing equation. Simulations were conducted with
+realistic coefficients related to physical parameters (anisotropies, beam
+orientation, diffusion). The stability of the numerical scheme is analyzed with
+time step and grid spacing tests for the pattern evolution, and the Method of
+Manufactured Solutions has been used to verify the proposed scheme. Ripples and
+hexagonal patterns were obtained from a monomodal initial condition for certain
+values of the damping coefficient, while spatiotemporal chaos appeared for
+lower values. The anisotropy effects on pattern formation were studied, varying
+the angle of incidence of the ion beam with respect to the irradiated surface.
+Analytical discussions are based on linear and weakly nonlinear analysis.",2104.14104v1
+2022-02-16,On the strong convergence of the trajectories of a Tikhonov regularized second order dynamical system with asymptotically vanishing damping,"This paper deals with a second order dynamical system with vanishing damping
+that contains a Tikhonov regularization term, in connection to the minimization
+problem of a convex Fr\'echet differentiable function $g$.
+  We show that for appropriate Tikhonov regularization parameters the value of
+the objective function in a generated trajectory converges fast to the global
+minimum of the objective function and a trajectory generated by the dynamical
+system converges weakly to a minimizer of the objective function. We also
+obtain the fast convergence of the velocities towards zero and some integral
+estimates. Nevertheless, our main goal is to extend and improve some recent
+results obtained in \cite{ABCR} and \cite{AL-nemkoz} concerning the strong
+convergence of the generated trajectories to an element of minimal norm from
+the $\argmin$ set of the objective function $g$. Our analysis also reveals that
+the damping coefficient and the Tikhonov regularization coefficient are
+strongly correlated.",2202.08980v1
+2023-05-06,Stochastic wave equation with Hölder noise coefficient: well-posedness and small mass limit,"We construct unique martingale solutions to the damped stochastic wave
+equation $$ \mu \frac{\partial^2u}{\partial t^2}(t,x)=\Delta
+u(t,x)-\frac{\partial u}{\partial
+t}(t,x)+b(t,x,u(t,x))+\sigma(t,x,u(t,x))\frac{dW_t}{dt},$$
+  where $\Delta$ is the Laplacian on $[0,1]$ with Dirichlet boundary condition,
+$W$ is space-time white noise, $\sigma$ is $\frac{3}{4}+\epsilon$ -H\""older
+continuous in $u$ and uniformly non-degenerate, and $b$ has linear growth. The
+same construction holds for the stochastic wave equation without damping term.
+More generally, the construction holds for SPDEs defined on separable Hilbert
+spaces with a densely defined operator $A$, and the assumed H\""older regularity
+on the noise coefficient depends on the eigenvalues of $A$ in a quantitative
+way. We further show the validity of the Smoluchowski-Kramers approximation:
+assume $b$ is H\""older continuous in $u$, then as $\mu$ tends to $0$ the
+solution to the damped stochastic wave equation converges in distribution, on
+the space of continuous paths, to the solution of the corresponding stochastic
+heat equation. The latter result is new even in the case of additive noise.",2305.04068v2
+2023-07-23,Visco-elastic damped wave models with time-dependent coefficient,"In this paper, we study the following Cauchy problem for linear visco-elastic
+damped wave models with a general time-dependent coefficient $g=g(t)$:
+\begin{equation} \label{EqAbstract} \tag{$\star$} \begin{cases} u_{tt}- \Delta
+u + g(t)(-\Delta)u_t=0, &(t,x) \in (0,\infty) \times \mathbb{R}^n, \\ u(0,x)=
+u_0(x),\quad u_t(0,x)= u_1(x), &x \in \mathbb{R}^n. \end{cases} \end{equation}
+We are interested to study the influence of the damping term $g(t)(-\Delta)u_t$
+on qualitative properties of solutions to \eqref{EqAbstract} as decay estimates
+for energies of higher order and the parabolic effect. The main tools are
+related to WKB-analysis. We apply elliptic as well as hyperbolic WKB-analysis
+in different parts of the extended phase space.",2307.12340v1
+2024-03-10,Linear-in-temperature resistivity and Planckian dissipation arise in a stochastic quantization model of Cooper pairs,"We suppose that a Cooper pair (CP) will experience a damping force exerted by
+the condensed matter. A Langevin equation of a CP in two dimensional condensed
+matter is established. Following a method similar to Nelson's stochastic
+mechanics, generalized Schr\""{o}dinger equation of a CP in condensed matter is
+derived. If the CPs move with a constant velocity, then the corresponding
+direct current (DC) electrical conductivity can be calculated. Therefore, a
+Drude like formula of resistivity of CPs is derived. We suppose that the
+damping coefficient of CPs in two dimensional cuprate superconductors is a
+linear function of temperature. Then the resistivity and scattering rate of CPs
+turn out to be also linear-in-temperature. The origin of linear-in-temperature
+resistivity and Planckian dissipation in cuprate superconductors may be the
+linear temperature dependence of the damping coefficient of CPs.",2403.09710v1
+2013-08-16,Quantum Gilbert-Varshamov Bound Through Symplectic Self-Orthogonal Codes,"It is well known that quantum codes can be constructed through classical
+symplectic self-orthogonal codes. In this paper, we give a kind of
+Gilbert-Varshamov bound for symplectic self-orthogonal codes first and then
+obtain the Gilbert-Varshamov bound for quantum codes. The idea of obtaining the
+Gilbert-Varshamov bound for symplectic self-orthogonal codes follows from
+counting arguments.",1308.3578v1
+2009-04-17,Plasmons and polaritons in a semi-infinite plasma and a plasma slab,"Plasmon and polariton modes are derived for an ideal semi-infinite
+(half-space) plasma and an ideal plasma slab by using a general, unifying
+procedure, based on equations of motion, Maxwell's equations and suitable
+boundary conditions. Known results are re-obtained in much a more direct manner
+and new ones are derived. The approach consists of representing the charge
+disturbances by a displacement field in the positions of the moving particles
+(electrons). The dielectric response and the electron energy loss are computed.
+The surface contribution to the energy loss exhibits an oscillatory behaviour
+in the transient regime near the surfaces. The propagation of an
+electromagnetic wave in these plasmas is treated by using the retarded
+electromagnetic potentials. The resulting integral equations are solved and the
+reflected and refracted waves are computed, as well as the reflection
+coefficient. For the slab we compute also the transmitted wave and the
+transmission coefficient. Generalized Fresnel's relations are thereby obtained
+for any incidence angle and polarization. Bulk and surface plasmon-polariton
+modes are identified. As it is well known, the field inside the plasma is
+either damped (evanescent) or propagating (transparency regime), and the
+reflection coefficient for a semi-infinite plasma exhibits an abrupt
+enhancement on passing from the propagating regime to the damped one (total
+reflection). Similarly, apart from characteristic oscillations, the reflection
+and transmission coefficients for a plasma slab exhibit an appreciable
+enhancement in the damped regime.",0904.2662v1
+2012-10-25,Molecular dissipation in the nonlinear eddy viscosity in the Navier-Stokes equations: modelling of accretion discs,"Physical damping, regarding the nonlinear Navier-Stokes viscous flow
+dynamics, refers to a tensorial turbulent dissipation term, attributed to
+adjacent moving macroscopic flow components. Mutual dissipation among these
+parts of fluid is described by a braking term in the momentum equation together
+with a heating term in the energy equation, both responsible of the damping of
+the momentum variation and of the viscous conversion of mechanical energy into
+heat. A macroscopic mixing scale length is currently the only characteristic
+length needed in the nonlinear modelling of viscous fluid dynamics describing
+the nonlinear eddy viscosity through the kinematic viscosity coefficient in the
+viscous stress tensor, without any reference to the chemical composition and to
+the atomic dimensions. Therefore, in this paper, we write a new formulation for
+the kinematic viscosity coefficient to the turbulent viscous physical
+dissipation in the Navier-Stokes equations, where molecular parameters are also
+included. Results of 2D tests are shown, where comparisons among flow
+structures are made on 2D shockless radial viscous transport and on 2D damping
+of collisional chaotic turbulence. An application to the 3D accretion disc
+modelling in low mass cataclysmic variables is also discussed. Consequences of
+the kinematic viscosity coefficient reformulation in a more strictly physical
+terms on the thermal conductivity coefficient for dilute gases are also
+discussed. The physical nature of the discussion here reported excludes any
+dependence by the pure mathematical aspect of the numerical modelling.",1210.6848v3
+2021-01-27,"New estimations of the added mass and damping of two cylinders vibrating in a viscous fluid, from theoretical and numerical approaches","This paper deals with the small oscillations of two circular cylinders
+immersed in a viscous stagnant fluid. A new theoretical approach based on an
+Helmholtz expansion and a bipolar coordinate system is presented to estimate
+the fluid forces acting on the two bodies. We show that these forces are linear
+combinations of the {\textcolor{black}{cylinder accelerations}} and velocities,
+through viscous fluid added coefficients. {\textcolor{black}{To assess the
+validity of this theory, we consider the case of two equal size cylinders, one
+of them being stationary while the other one is forced sinusoidally}}. The
+self-added mass and damping coefficients are shown to decrease with both the
+Stokes number and the separation distance. The cross-added mass and damping
+coefficients tend to increase with the Stokes number and the separation
+distance. Compared to the inviscid results, the effect of viscosity is to add a
+correction term which scales as $Sk^{-1/2}$. When the separation distance is
+sufficiently large, the two cylinders behave as if they were independent and
+the Stokes predictions for an isolated cylinder are recovered. Compared to
+previous works, the present theory offers a simple and flexible alternative for
+an easy determination of the fluid forces and related added coefficients. To
+our knowledge, this is also the first time that a numerical approach based on a
+penalization method is presented in the context of fluid-structure interactions
+for relatively small Stokes numbers, and successfully compared to theoretical
+predictions.",2101.11346v1
+2022-09-18,Design of a stiffness adjustable magnetic fluid shock absorber based on optimal stiffness coefficient,"With the rapid development of aerospace technology, the vibration problem of
+the spacecraft flexible structure urgently needs to be solved. Magnetic fluids
+are a type of multi-functional smart materials, which can be employed in shock
+absorbers to eliminate these vibrations. Referring to the calculation methods
+of stiffness coefficients of other passive dampers, the stiffness coefficient
+formula of magnetic fluid shock absorbers (MFSAs) was derived. Meanwhile, a
+novel stiffness adjustable magnetic fluid shock absorber (SA-MFSA) was
+proposed. On the basis of the second-order buoyancy principle, a series of
+SA-MFSAs were fabricated. The range of stiffness coefficients covered by these
+SA-MFSAs contains the optimal stiffness coefficient estimated by formulas. The
+repulsive force measurement and vibration attenuation experiments were
+conducted on these SA-MFSAs. In the case of small amplitude, the relationship
+between the repulsive force and the offset distance was linear. The simulation
+and experiment curves of repulsive forces were in good agreement. The results
+of vibration attenuation experiments demonstrated that the rod length and the
+magnetic fluid mass influence the damping efficiency of SA-MFSAs. In addition,
+these results verified that the SA-MFSA with the optimal stiffness coefficient
+performed best. Therefore, the stiffness coefficient formula can guide the
+design of MFSAs.",2209.08588v1
+2017-02-03,Enhanced Spin Conductance of a Thin-Film Insulating Antiferromagnet,"We investigate spin transport by thermally excited spin waves in an
+antiferromagnetic insulator. Starting from a stochastic Landau-Lifshitz-Gilbert
+phenomenology, we obtain the out-of-equilibrium spin-wave properties. In linear
+response to spin biasing and a temperature gradient, we compute the spin
+transport through a normal metal$|$antiferromagnet$|$normal metal
+heterostructure. We show that the spin conductance diverges as one approaches
+the spin-flop transition; this enhancement of the conductance should be readily
+observable by sweeping the magnetic field across the spin-flop transition. The
+results from such experiments may, on the one hand, enhance our understanding
+of spin transport near a phase transition, and on the other be useful for
+applications that require a large degree of tunability of spin currents. In
+contrast, the spin Seebeck coefficient does not diverge at the spin-flop
+transition. Furthermore, the spin Seebeck coefficient is finite even at zero
+magnetic field, provided that the normal metal contacts break the symmetry
+between the antiferromagnetic sublattices.",1702.00975v2
+2022-03-09,Finiteness for Hecke algebras of $p$-adic groups,"Let $G$ be a reductive group over a non-archimedean local field $F$ of
+residue characteristic $p$. We prove that the Hecke algebras of $G(F)$ with
+coefficients in a ${\mathbb Z}_{\ell}$-algebra $R$ for $\ell$ not equal to $p$
+are finitely generated modules over their centers, and that these centers are
+finitely generated $R$-algebras. Following Bernstein's original strategy, we
+then deduce that ""second adjointness"" holds for smooth representations of
+$G(F)$ with coefficients in any ring $R$ in which $p$ is invertible. These
+results had been conjectured for a long time. The crucial new tool that unlocks
+the problem is the Fargues-Scholze morphism between a certain ""excursion
+algebra"" defined on the Langlands parameters side and the Bernstein center of
+$G(F)$. Using this bridge, our main results are representation theoretic
+counterparts of the finiteness of certain morphisms between coarse moduli
+spaces of local Langlands parameters that we also prove here, which may be of
+independent interest",2203.04929v2
+2022-05-04,Separations in Proof Complexity and TFNP,"It is well-known that Resolution proofs can be efficiently simulated by
+Sherali-Adams (SA) proofs. We show, however, that any such simulation needs to
+exploit huge coefficients: Resolution cannot be efficiently simulated by SA
+when the coefficients are written in unary. We also show that Reversible
+Resolution (a variant of MaxSAT Resolution) cannot be efficiently simulated by
+Nullstellensatz (NS).
+  These results have consequences for total NP search problems. First, we
+characterise the classes PPADS, PPAD, SOPL by unary-SA, unary-NS, and
+Reversible Resolution, respectively. Second, we show that, relative to an
+oracle, PLS $\not\subseteq$ PPP, SOPL $\not\subseteq$ PPA, and EOPL
+$\not\subseteq$ UEOPL. In particular, together with prior work, this gives a
+complete picture of the black-box relationships between all classical TFNP
+classes introduced in the 1990s.",2205.02168v2
+2002-04-29,Schwarzschild black holes and propagation of electromagnetic and gravitational waves,"Disturbing of a spacetime geometry may result in the appearance of an
+oscillating and damped radiation - the so-called quasinormal modes. Their
+periods of oscillations and damping coefficients carry unique information about
+the mass and the angular momentum, that would allow one to identify the source
+of the gravitational field. In this talk we present recent bounds on the
+diffused energy, applicable to the Schwarzschild spacetime, that give also
+rough estimates of the energy of excited quasinormal modes.",0204086v1
+2002-09-21,Infrared Sensitivity in Damping Rate for Very Soft Moving Fermions in Finite Temperature QED,"We calculate the fermion damping rate to second order in powers of the
+external momentum $p$ in the context of QED at finite temperature using the
+hard-thermal-loop (HTL) summation scheme. We find that the coefficient of order
+$p^{2}$ is divergent in the infrared whereas the two others are finite. This
+result suggests that the htl-based pertubation is infrared sensitive at
+next-to-leading order.",0209246v1
+2004-10-11,Nodal two-dimensional solitons in nonlinear parametric resonance,"The parametrically driven damped nonlinear Schr\""odinger equation serves as
+an amplitude equation for a variety of resonantly forced oscillatory systems on
+the plane. In this note, we consider its nodal soliton solutions. We show that
+although the nodal solitons are stable against radially-symmetric perturbations
+for sufficiently large damping coefficients, they are always unstable to
+azimuthal perturbations. The corresponding break-up scenarios are studied using
+direct numerical simulations. Typically, the nodal solutions break into
+symmetric ""necklaces"" of stable nodeless solitons.",0410012v1
+2006-10-22,Response of a Magneto-Rheological Fluid Damper Subjected to Periodic Forcing in a High Frequency Limit,"We explored vibrations of a single-degree of freedom oscillator with a
+magneto-rheological damper subjected to kinematic excitations. Using fast and
+slow scales decoupling procedure we derived an effective damping coefficient in
+the limit of high frequency excitation. Damping characteristics, as functions
+of velocity, change considerably especially by terminating the singular
+non-smoothness points. This effect was more transparent for a larger control
+parameter which was defined as the product of the excitation amplitude and its
+frequency.",0610055v1
+2006-09-19,Quantum master equations from classical Lagrangians with two stochastic forces,"We show how a large family of master equations, describing quantum Brownian
+motion of a harmonic oscillator with translationally invariant damping, can be
+derived within a phenomenological approach, based on the assumption that an
+environment can be simulated by two classical stochastic forces. This family is
+determined by three time-dependent correlation functions (besides the frequency
+and damping coefficients), and it includes as special cases the known master
+equations, whose dissipative part is bilinear with respect to the operators of
+coordinate and momentum.",0609144v3
+2007-05-31,Stability of Solutions to Damped Equations with Negative Stiffness,"This article concerns the stability of a model for mass-spring systems with
+positive damping and negative stiness. It is well known that when the
+coefficients are frozen in time the system is unstable. Here we find conditions
+on the variable cofficients to prove stability. In particular, we disprove the
+believe that if the eigenvalues of the system change slowly in time the system
+remains unstable. We extend some of our results for nonlinear systems.",0705.4670v1
+2009-10-05,Construction of quasi-periodic response solutions in forced strongly dissipative systems,"We consider a class of ordinary differential equations describing
+one-dimensional quasiperiodically forced systems in the presence of large
+damping. We give a fully constructive proof of the existence of response
+solutions, that is quasi-periodic solutions which have the same frequency
+vector as the forcing. This requires dealing with a degenerate implicit
+function equation: we prove that the latter has a unique solution, which can be
+explicitly determined. As a by-product we obtain an explicit estimate of the
+minimal size of the damping coefficient.",0910.0746v1
+2009-11-12,A new perspective on supersymmetric inflation,"We consider supersymmetric inflation with the hybrid-type potential. In the
+absence of the symmetry that forbids Hubble-induced mass terms, the inflaton
+mass will be as large as the Hubble scale during inflation. We consider
+gravitational decay of the trigger field as the least decay mode and find that
+the damping caused by the dissipation can dominate the friction of the inflaton
+when the heavy trigger field is coupled to the inflaton. The dissipative
+damping provides a solution to the traditional $\eta$ problem without
+introducing additional symmetry and interactions. Considering the spatial
+inhomogeneities of the dissipative coefficient, we find that modulated
+inflation (modulation of the inflaton velocity) can create significant
+curvature perturbations.",0911.2350v1
+2010-09-09,The Damped String Problem Revisited,"We revisit the damped string equation on a compact interval with a variety of
+boundary conditions and derive an infinite sequence of trace formulas
+associated with it, employing methods familiar from supersymmetric quantum
+mechanics. We also derive completeness and Riesz basis results (with
+parentheses) for the associated root functions under less smoothness
+assumptions on the coefficients than usual, using operator theoretic methods
+(rather than detailed eigenvalue and root function asymptotics) only.",1009.1858v1
+2012-01-26,Inhomogeneous spin diffusion in traps with cold atoms,"The spin diffusion and damped oscillations are studied in the collision of
+two spin polarized clouds of cold atoms with resonant interactions. The strong
+density dependence of the diffusion coefficient leads to inhomogeneous spin
+diffusion that changes from central to surface spin flow as the temperature
+increases. The inhomogeneity and the smaller finite trap size significantly
+reduce the spin diffusion rate at low temperatures. The resulting spin
+diffusion rates, spin drag and initial damped oscillations are compatible with
+measurements at low to high temperatures for resonant attractive interactions
+but are incompatible with a metastable ferromagnetic phase.",1201.5526v2
+2012-07-31,An analytic description of the damping of gravitational waves by free streaming neutrinos,"We provide an analytic solution to the general wavelength
+integro-differential equation describing the damping of tensor modes of
+gravitational waves due to free streaming neutrinos in the early universe. Our
+result is expressed as a series of spherical Bessel functions whose
+coefficients are functions of the reduced wave number $Q$.",1207.7285v4
+2013-07-17,Functional inequalities on path space over a non-compact Riemannian manifold,"We prove the existence of the O-U Dirichlet form and the damped O-U Dirichlet
+form on path space over a general non-compact Riemannian manifold which is
+complete and stochastically complete. We show a weighted log-Sobolev inequality
+for the O-U Dirichlet form and the (standard) log-Sobolev inequality for the
+damped O-U Dirichlet form. In particular, the Poincar\'e inequality (and the
+super Poincar\'e inequality) can be established for the O-U Dirichlet form on
+path space over a class of Riemannian manifolds with unbounded Ricci
+curvatures. Moreover, we construct a large class of quasi-regular local
+Dirichlet forms with unbounded random diffusion coefficients on the path space
+over a general non-compact manifold.",1307.4482v2
+2016-04-27,Temperature Dependence Calibration and Correction of the DAMPE BGO Electromagnetic Calorimeter,"A BGO electromagnetic calorimeter (ECAL) is built for the DArk Matter
+Particle Explorer (DAMPE) mission. The effect of temperature on the BGO ECAL
+was investigated with a thermal vacuum experiment. The light output of a BGO
+crystal depends on temperature significantly. The temperature coefficient of
+each BGO crystal bar has been calibrated, and a correction method is also
+presented in this paper.",1604.08060v1
+2017-11-06,Linear inviscid damping and enhanced dissipation for the Kolmogorov flow,"In this paper, we prove the linear inviscid damping and voticity depletion
+phenomena for the linearized Euler equations around the Kolmogorov flow. These
+results confirm Bouchet and Morita's predictions based on numerical analysis.
+By using the wave operator method introduced by Li, Wei and Zhang, we solve
+Beck and Wayne's conjecture on the optimal enhanced dissipation rate for the
+2-D linearized Navier-Stokes equations around the bar state called Kolmogorov
+flow. The same dissipation rate is proved for the Navier-Stokes equations if
+the initial velocity is included in a basin of attraction of the Kolmogorov
+flow with the size of $\nu^{\frac 23+}$, here $\nu$ is the viscosity
+coefficient.",1711.01822v1
+2018-02-26,Controllability and observability for non-autonomous evolution equations: the averaged Hautus test,"We consider the observability problem for non-autonomous evolution systems
+(i.e., the operators governing the system depend on time). We introduce an
+averaged Hautus condition and prove that for skew-adjoint operators it
+characterizes exact observability. Next, we extend this to more general class
+of operators under a growth condition on the associated evolution family. We
+give an application to the Schr\""odinger equation with time dependent potential
+and the damped wave equation with a time dependent damping coefficient.",1802.09224v1
+2018-03-15,Improving the capacity of quantum dense coding by weak measurement and reversal measurement,"A protocol of quantum dense coding protection of two qubits is proposed in
+amplitude damping (AD) channel using weak measurement and reversal measurement.
+It is found that the capacity of quantum dense coding under the weak
+measurement and reversal measurement is always greater than that without weak
+measurement and reversal measurement. When the protocol is applied, for the AD
+channels with different damping coefficient, the result reflects that quantum
+entanglement can be protected and quantum dense coding becomes successful.",1803.05678v1
+2018-09-25,On the energy decay rates for the 1D damped fractional Klein-Gordon equation,"We consider the fractional Klein-Gordon equation in one spatial dimension,
+subjected to a damping coefficient, which is non-trivial and periodic, or more
+generally strictly positive on a periodic set. We show that the energy of the
+solution decays at the polynomial rate $O(t^{-\frac{s}{4-2s}})$ for $0< s<2 $
+and at some exponential rate when $s\geq 2$. Our approach is based on the
+asymptotic theory of $C_0$ semigroups in which one can relate the decay rate of
+the energy in terms of the resolvent growth of the semigroup generator. The
+main technical result is a new observability estimate for the fractional
+Laplacian, which may be of independent interest.",1809.09531v1
+2019-09-11,Remark on global existence of solutions to the 1D compressible Euler equation with time-dependent damping,"In this paper, we consider the 1D compressible Euler equation with the
+damping coefficient $\lambda/(1+t)^{\mu}$. Under the assumption that $0\leq \mu
+<1$ and $\lambda >0$ or $\mu=1$ and $\lambda > 2$, we prove that solutions
+exist globally in time, if initial data are small $C^1$ perturbation near
+constant states. In particular, we remove the conditions on the limit
+$\lim_{|x| \rightarrow \infty} (u (0,x), v (0,x))$, assumed in previous
+results.",1909.05683v1
+2020-07-24,Convergence Rates of Inertial Primal-Dual Dynamical Methods for Separable Convex Optimization Problems,"In this paper, we propose a second-order continuous primal-dual dynamical
+system with time-dependent positive damping terms for a separable convex
+optimization problem with linear equality constraints. By the Lyapunov function
+approach, we investigate asymptotic properties of the proposed dynamical system
+as the time $t\to+\infty$. The convergence rates are derived for different
+choices of the damping coefficients. We also show that the obtained results are
+robust under external perturbations.",2007.12428v1
+2021-02-14,Suppression of singularities of solutions of the Euler-Poisson system with density-dependent damping,"We find a sharp condition on the density-dependent coefficient of damping of
+a one-dimensional repulsive Euler-Poisson system, which makes it possible to
+suppress the formation of singularities in the solution of the Cauchy problem
+with arbitrary smooth data. In the context of plasma physics, this means the
+possibility of suppressing the breakdown of arbitrary oscillations of cold
+plasma.",2102.07176v2
+2021-02-28,The influence of the physical coefficients of a Bresse system with one singular local viscous damping in the longitudinal displacement on its stabilization,"In this paper, we investigate the stabilization of a linear Bresse system
+with one singular local frictional damping acting in the longitudinal
+displacement, under fully Dirichlet boundary conditions. First, we prove the
+strong stability of our system. Next, using a frequency domain approach
+combined with the multiplier method, we establish the exponential stability of
+the solution if and only if the three waves have the same speed of propagation.
+On the contrary, we prove that the energy of our system decays polynomially
+with rates $t^{-1}$ or $t^{-\frac{1}{2}}$.",2103.00628v2
+2021-11-11,Stabilization for Euler-Bernoulli beam equation with a local degenerated Kelvin-Voigt damping,"We consider the Euler-Bernoulli beam equation with a local Kelvin-Voigt
+dissipation type in the interval $(-1,1)$. The coefficient damping is only
+effective in $(0,1)$ and is degenerating near the $0$ point with a speed at
+least equal to $x^{\alpha}$ where $\alpha\in(0,5)$. We prove that the semigroup
+corresponding to the system is polynomially stable and the decay rate depends
+on the degeneracy speed $\alpha$.",2111.06431v1
+2022-01-22,Absorption of charged particles in Perfectly-Matched-Layers by optimal damping of the deposited current,"Perfectly-Matched Layers (PML) are widely used in Particle-In-Cell
+simulations, in order to absorb electromagnetic waves that propagate out of the
+simulation domain. However, when charged particles cross the interface between
+the simulation domain and the PMLs, a number of numerical artifacts can arise.
+In order to mitigate these artifacts, we introduce a new PML algorithm whereby
+the current deposited by the macroparticles in the PML is damped by an
+analytically-derived, optimal coefficient. The benefits of this new algorithm
+is illustrated in practical simulations.",2201.09084v2
+2023-02-23,Hopf-Like Bifurcation in a Wave Equation at a Removable Singularity,"It is shown that a one-dimensional damped wave equation with an odd time
+derivative nonlinearity exhibits small amplitude bifurcating time periodic
+solutions, when the bifurcation parameter is the linear damping coefficient is
+positive and accumulates to zero. The upshot is that the singularity of the
+linearized operator at criticality which stems from the well known small
+divisor problem for the wave operator, is entirely removed without the need to
+exclude parameters via Diophantine conditions, nor the use of accelerated
+convergence schemes. Only the contraction mapping principle is used.",2302.12092v2
+2023-03-24,Exponential decay estimates for semilinear wave-type equations with time-dependent time delay,"In this paper, we analyze a semilinear damped second order evolution equation
+with time-dependent time delay and time-dependent delay feedback coefficient.
+The nonlinear term satisfies a local Lipschitz continuity assumption. Under
+appropriate conditions, we prove well-posedness and exponential stability of
+our model for small initial data. Our arguments combine a Lyapunov functional
+approach with some continuity arguments. Moreover, as an application of our
+abstract results, the damped wave equation with a source term and delay
+feedback is analyzed.",2303.14208v1
+2023-06-13,Stability of asymptotically Hamiltonian systems with damped oscillatory and stochastic perturbations,"A class of asymptotically autonomous systems on the plane with oscillatory
+coefficients is considered. It is assumed that the limiting system is
+Hamiltonian with a stable equilibrium. The effect of damped multiplicative
+stochastic perturbations of white noise type on the stability of the system is
+discussed. It is shown that different long-term asymptotic regimes for
+solutions are admissible in the system and the stochastic stability of the
+equilibrium depends on the realized regime. In particular, we show that stable
+phase locking is possible in the system due to decaying stochastic
+perturbations. The proposed analysis is based on a combination of the averaging
+technique and the construction of stochastic Lyapunov functions.",2306.07694v1
+2023-07-27,Best Ulam constants for damped linear oscillators with variable coefficients,"This study uses an associated Riccati equation to study the Ulam stability of
+non-autonomous linear differential vector equations that model the damped
+linear oscillator. In particular, the best (minimal) Ulam constants for these
+non-autonomous linear differential vector equations are derived. These robust
+results apply to vector equations with solutions that blow up in finite time,
+as well as to vector equations with solutions that exist globally on
+$(-\infty,\infty)$. Illustrative, non-trivial examples are presented,
+highlighting the main results.",2307.15103v1
+2023-09-04,On the small-mass limit for stationary solutions of stochastic wave equations with state dependent friction,"We investigate the convergence, in the small mass limit, of the stationary
+solutions of a class of stochastic damped wave equations, where the friction
+coefficient depends on the state and the noisy perturbation if of
+multiplicative type. We show that the Smoluchowski-Kramers approximation that
+has been previously shown to be true in any fixed time interval, is still valid
+in the long time regime. Namely we prove that the first marginals of any
+sequence of stationary solutions for the damped wave equation converge to the
+unique invariant measure of the limiting stochastic quasilinear parabolic
+equation. The convergence is proved with respect to the Wasserstein distance
+associated with the $H^{-1}$ norm.",2309.01549v1
+2023-09-21,Inverse problems for a quasilinear strongly damped wave equation arising in nonlinear acoustics,"We consider inverse problems for a Westervelt equation with a strong damping
+and a time-dependent potential $q$. We first prove that all boundary
+measurements, including the initial data, final data, and the lateral boundary
+measurements, uniquely determine $q$ and the nonlinear coefficient $\beta$. The
+proof is based on complex geometric optics construction and the approach
+proposed by Isakov. Further, by considering fundamental solutions supported in
+a half-space constructed by H\""ormander, we prove that with vanishing initial
+conditions the Dirichlet-to-Neumann map determines $q$ and $\beta$.",2309.11775v1
+2023-12-29,On damping a control system of arbitrary order with global aftereffect on a tree,"We study a problem of damping a control system described by
+functional-differential equations of natural order $n$ and neutral type with
+non-smooth complex coefficients on an arbitrary tree with global delay. The
+latter means that the delay propagates through internal vertices of the tree.
+Minimization of the energy functional of the system leads to a variational
+problem. We establish its equivalence to a certain self-adjoint boundary value
+problem on the tree for equations of order $2n$ with nonlocal quasi-derivatives
+and multidirectional shifts of the argument, as well as Kirchhoff-type
+conditions emerging at the internal vertices. The unique solvability of both
+problems is proved.",2312.17592v1
+2024-01-11,Weak collision effect on nonlinear Landau damping for the Vlasov-Poisson-Fokker-Planck system,"We investigate the impact of weak collisions on Landau damping in the
+Vlasov-Poisson-Fokker-Planck system on a torus, specifically focusing on its
+proximity to a Maxwellian distribution. In the case where the Gevrey index
+satisfies $\frac{1}{s}<3$, we establish the global stability and enhanced
+dissipation of small initial data, which remain unaffected by the small
+diffusion coefficient $\nu$. For Gevrey index $\frac{1}{s}\ge3$, we prove the
+global stability and enhanced dissipation of initial data, whose size is on the
+order of $O(\nu^a)$ for any $a>\frac{1-3s}{3-3s}$. Our analysis provides
+insights into the effects of phase mixing, enhanced dissipation, and plasma
+echoes.",2401.05601v3
+2014-11-24,Damping of liquid sloshing by foams,"When a container is set in motion, the free surface of the liquid starts to
+oscillate or slosh. Such effects can be observed when a glass of water is
+handled carelessly and the fluid sloshes or even spills over the rims of the
+container. However, beer does not slosh as readily as water, which suggests
+that foam could be used to damp sloshing. In this work, we study experimentally
+the effect on sloshing of a liquid foam placed on top of a liquid bath. We
+generate a monodisperse two-dimensional liquid foam in a rectangular container
+and track the motion of the foam. The influence of the foam on the sloshing
+dynamics is experimentally characterized: only a few layers of bubbles are
+sufficient to significantly damp the oscillations. We rationalize our
+experimental findings with a model that describes the foam contribution to the
+damping coefficient through viscous dissipation on the walls of the container.
+Then we extend our study to confined three-dimensional liquid foam and observe
+that the behavior of 2D and confined 3D systems are very similar. Thus we
+conclude that only the bubbles close to the walls have a significant impact on
+the dissipation of energy. The possibility to damp liquid sloshing using foam
+is promising in numerous industrial applications such as the transport of
+liquefied gas in tankers or for propellants in rocket engines.",1411.6542v2
+2019-05-22,Ultra-low magnetic damping in Co 2 Mn-based Heusler compounds: promising materials for spintronic,"The prediction of ultra-low magnetic damping in Co 2 MnZ Heusler half-metal
+thin-film magnets is explored in this study and the damping response is shown
+to be linked to the underlying electronic properties. By substituting the Z
+elements in high crystalline quality films (Co 2 MnZ with Z=Si, Ge, Sn, Al, Ga,
+Sb), electronic properties such as the minority spin band gap, Fermi energy
+position in the gap and spin polarization can be tuned and the consequence on
+magnetization dynamics analyzed. The experimental results allow us to directly
+explore the interplay of spin polarization, spin gap, Fermi energy position and
+the magnetic damping obtained in these films, together with ab initio
+calculation predictions. The ultra-low magnetic damping coefficients measured
+in the range 4.1 10-4-9 10-4 for Co 2 MnSi, Ge, Sn, Sb are the lowest values
+obtained on a conductive layer and offers a clear experimental demonstration of
+theoretical predictions on Half-Metal Magnetic Heusler compounds and a pathway
+for future materials design.",1905.08987v1
+2019-07-29,Breather arrest in a chain of damped oscillators with Hertzian contact,"We explore breather propagation in the damped oscillatory chain with
+essentially nonlinear (non-linearizable) nearest-neighbour coupling.
+Combination of the damping and the substantially nonlinear coupling leads to
+rather unusual two-stage pattern of the breather propagation. The first stage
+occurs at finite fragment of the chain and is characterized by power-law decay
+of the breather amplitude. The second stage is characterized by extremely small
+breather amplitudes that decay hyper-exponentially with the site number. Thus,
+practically, one can speak about finite penetration depth of the breather. This
+phenomenon is referred to as breather arrest (BA). As particular example, we
+explore the chain with Hertzian contacts. Dependencies of the breather
+penetration depth on the initial excitation and on the damping coefficient on
+the breather penetration depth obey power laws. The results are rationalized by
+considering beating responses in a system of two damped linear oscillators with
+strongly nonlinear (non-linearizable) coupling. Initial excitation of one of
+these oscillators leads to strictly finite number of beating cycles. Then, the
+beating cycle in this simplified system is associated with the passage of the
+discrete breather between the neighbouring sites in the chain. Somewhat
+surprisingly, this simplified model reliably predicts main quantitative
+features of the breather arrest in the chain, including the exponents in
+numerically observed power laws.",1907.12462v1
+2019-12-09,Analytical solution of linearized equations of the Morris-Lecar neuron model at large constant stimulation,"The classical biophysical Morris-Lecar model of neuronal excitability
+predicts that upon stimulation of the neuron with a sufficiently large constant
+depolarizing current there exists a finite interval of the current values where
+periodic spike generation occurs. Above the upper boundary of this interval,
+there is four-stage damping of the spike amplitude: 1) minor primary damping,
+which reflects a typical transient to stationary dynamic state, 2) plateau of
+nearly undamped periodic oscillations, 3) strong damping, and 4) reaching a
+constant asymptotic value of the neuron potential. We have shown that in the
+vicinity of the asymptote the Morris-Lecar equations can be reduced to the
+standard equation for exponentially damped harmonic oscillations. Importantly,
+all coefficients of this equation can be explicitly expressed through
+parameters of the original Morris-Lecar model, enabling direct comparison of
+the numerical and analytical solutions for the neuron potential dynamics at
+later stages of the spike amplitude damping.",1912.04083v4
+2022-05-10,Nonlinear damping quantification from phase-resonant tests under base excitation,"The present work addresses the experimental identification of
+amplitude-dependent modal parameters (modal frequency, damping ratio, Fourier
+coefficients of periodic modal oscillation). Phase-resonant testing has emerged
+as an important method for this task, as it substantially reduces the amount of
+data required for the identification compared to conventional
+frequency-response testing at different excitation/response levels. In the case
+of shaker-stinger excitation, the applied excitation force is commonly measured
+in order to quantify the amplitude-dependent modal damping ratio from the
+phase-resonant test data. In the case of base excitation, however, the applied
+excitation force is challenging or impossible to measure. In this work we
+develop an original method for damping quantification from phase-resonant
+tests. It relies solely on response measurement; it avoids the need to resort
+to force measurement. The key idea is to estimate the power provided by the
+distributed inertia force imposed by the base motion. We develop both a
+model-free and a model-based variant of the method. We validate the developed
+method first in virtual experiments of a friction-damped and a geometrically
+nonlinear system, and then in a physical experiment involving a thin beam
+clamped at both ends via bolted joints. We conclude that the method is highly
+robust and provides high accuracy already for a reasonable number of sensors.",2205.04735v1
+2001-11-16,Resonances and superlattice pattern stabilization in two-frequency forced Faraday waves,"We investigate the role weakly damped modes play in the selection of Faraday
+wave patterns forced with rationally-related frequency components m*omega and
+n*omega. We use symmetry considerations to argue for the special importance of
+the weakly damped modes oscillating with twice the frequency of the critical
+mode, and those oscillating primarily with the ""difference frequency""
+|n-m|*omega and the ""sum frequency"" (n+m)*omega. We then perform a weakly
+nonlinear analysis using equations of Zhang and Vinals (1997, J. Fluid Mech.
+336) which apply to small-amplitude waves on weakly inviscid, semi-infinite
+fluid layers. For weak damping and forcing and one-dimensional waves, we
+perform a perturbation expansion through fourth order which yields analytical
+expressions for onset parameters and the cubic bifurcation coefficient that
+determines wave amplitude as a function of forcing near onset. For stronger
+damping and forcing we numerically compute these same parameters, as well as
+the cubic cross-coupling coefficient for competing waves travelling at an angle
+theta relative to each other. The resonance effects predicted by symmetry are
+borne out in the perturbation results for one spatial dimension, and are
+supported by the numerical results in two dimensions. The difference frequency
+resonance plays a key role in stabilizing superlattice patterns of the SL-I
+type observed by Kudrolli, Pier and Gollub (1998, Physica D 123).",0111039v2
+2019-07-08,Single-spectrum prediction of kurtosis of water waves in a non-conservative model,"We study statistical properties after a sudden episode of wind for water
+waves propagating in one direction. A wave with random initial conditions is
+propagated using a forced-damped higher order Nonlinear Schr\""odinger equation
+(NLS). During the wind episode, the wave action increases, the spectrum
+broadens, the spectral mean shifts up and the Benjamin-Feir index (BFI) and the
+kurtosis increase. Conversely, after the wind episode, the opposite occurs for
+each quantity. The kurtosis of the wave height distribution is considered the
+main parameter that can indicate whether rogue waves are likely to occur in a
+sea state, and the BFI is often mentioned as a means to predict the kurtosis.
+However, we find that while there is indeed a quadratic relation between these
+two, this relationship is dependent on the details of the forcing and damping.
+Instead, a simple and robust quadratic relation does exist between the kurtosis
+and the bandwidth. This could allow for a single-spectrum assessment of the
+likelihood of rogue waves in a given sea state. In addition, as the kurtosis
+depends strongly on the damping and forcing coefficients, by combining the
+bandwidth measurement with the damping coefficient, the evolution of the
+kurtosis after the wind episode can be predicted.",1907.03490v1
+2020-07-19,Global existence and convergence to the modified Barenblatt solution for the compressible Euler equations with physical vacuum and time-dependent damping,"In this paper, the smooth solution of the physical vacuum problem for the one
+dimensional compressible Euler equations with time-dependent damping is
+considered. Near the vacuum boundary, the sound speed is $C^{1/2}$-H\""{o}lder
+continuous. The coefficient of the damping depends on time, given by this form
+$\frac{\mu}{(1+t)^\lambda}$, $\lambda$, $\mu>0$, which decays by order
+$-\lambda$ in time. Under the assumption that $0<\lambda<1$, $0<\mu$ or
+$\lambda=1$, $2<\mu$, we will prove the global existence of smooth solutions
+and convergence to the modified Barenblatt solution of the related porous media
+equation with time-dependent dissipation and the same total mass when the
+initial data of the Euler equations is a small perturbation of that of the
+Barenblatt solution. The pointwise convergence rates of the density, velocity
+and the expanding rate of the physical vacuum boundary are also given. The
+proof is based on space-time weighted energy estimates, elliptic estimates and
+Hardy inequality in the Lagrangian coordinates. Our result is an extension of
+that in Luo-Zeng [Comm. Pure Appl. Math. 69 (2016), no. 7, 1354-1396], where
+the authors considered the physical vacuum free boundary problem of the
+compressible Euler equations with constant-coefficient damping.",2007.14802v2
+2018-10-30,Effect of Landau damping on ion acoustic solitary waves in a multi-species collisionless unmagnetized plasma consisting of nonthermal and isothermal electrons,"A Korteweg-de Vries (KdV) equation including the effect of Landau damping is
+derived to study the propagation of weakly nonlinear and weakly dispersive ion
+acoustic waves in a collisionless unmagnetized plasma consisting of warm
+adiabatic ions and two different species of electrons at different
+temperatures. The hotter energetic electron species follows the nonthermal
+velocity distribution of Cairns et al. [Geophys. Res. Lett. 22, 2709 (1995)]
+whereas the cooler electron species obeys the Boltzmann distribution. It is
+found that the coefficient of the nonlinear term of this KdV like evolution
+equation vanishes along different family of curves in different parameter
+planes. In this context, a modified KdV (MKdV) equation including the effect of
+Landau damping effectively describes the nonlinear behaviour of ion acoustic
+waves. It has also been observed that the coefficients of the nonlinear terms
+of the KdV and MKdV like evolution equations including the effect of Landau
+damping, are simultaneously equal to zero along a family of curves in the
+parameter plane. In this situation, we have derived a further modified KdV
+(FMKdV) equation including the effect of Landau damping to describe the
+nonlinear behaviour of ion acoustic waves. In fact, different modified KdV like
+evolution equations including the effect of Landau damping have been derived to
+describe the nonlinear behaviour of ion acoustic waves in different region of
+parameter space. The method of Ott & Sudan [Phys. Fluids 12, 2388 (1969)] has
+been applied to obtain the solitary wave solution of the evolution equation
+having the nonlinear term $(\phi^{(1)})^{r}\frac{\partial \phi^{(1)}}{\partial
+\xi}$, where $\phi^{(1)}$ is the first order perturbed electrostatic potential
+and $r =1,2,3$. We have found that the amplitude of the solitary wave solution
+decreases with time for all $r =1,2,3$.",1810.12739v1
+2003-01-15,Resonant triad dynamics in weakly damped Faraday waves with two-frequency forcing,"Many of the interesting patterns seen in recent multi-frequency Faraday
+experiments can be understood on the basis of three-wave interactions (resonant
+triads). In this paper we consider two-frequency forcing and focus on a
+resonant triad that occurs near the bicritical point where two pattern-forming
+modes with distinct wavenumbers emerge simultaneously. This triad has been
+observed directly (in the form of rhomboids) and has also been implicated in
+the formation of quasipatterns and superlattices. We show how the symmetries of
+the undamped unforced problem (time translation, time reversal, and Hamiltonian
+structure) can be used, when the damping is weak, to obtain general scaling
+laws and additional qualitative properties of the normal form coefficients
+governing the pattern selection process near onset; such features help to
+explain why this particular triad is seen only for certain ""low"" forcing
+ratios, and predict the existence of drifting solutions and heteroclinic
+cycles. We confirm the anticipated parameter dependence of the coefficients and
+investigate its dynamical consequences using coefficients derived numerically
+from a quasipotential formulation of the Faraday problem due to Zhang and
+Vinals.",0301015v1
+2011-04-25,Exactly Solvable Nonhomogeneous Burgers Equations with Variable Coefficients,"We consider a nonhomogeneous Burgers equation with time variable
+coefficients, and obtain an explicit solution of the general initial value
+problem in terms of solution to a corresponding linear ODE. Special exact
+solutions such as generalized shock and multi-shock solitary waves, triangular
+wave, N-wave and rational type solutions are found and discussed. As exactly
+solvable models, we study forced Burgers equations with constant damping and an
+exponentially decaying diffusion coefficient. Different type of exact solutions
+are obtained for the critical, over and under damping cases, and their behavior
+is illustrated explicitly. In particular, the existence of inelastic type of
+collisions is observed by constructing multi-shock solitary wave solutions, and
+for the rational type solutions the motion of the pole singularities is
+described.",1104.4717v1
+2011-06-03,Shear viscous effects on the primordial power spectrum from warm inflation,"We compute the primordial curvature spectrum generated during warm inflation,
+including shear viscous effects. The primordial spectrum is dominated by the
+thermal fluctuations of the radiation bath, sourced by the dissipative term of
+the inflaton field. The dissipative coefficient \Upsilon, computed from first
+principles in the close-to-equilibrium approximation, depends in general on the
+temperature T, and this dependence renders the system of the linear
+fluctuations coupled. Whenever the dissipative coefficient is larger than the
+Hubble expansion rate H, there is a growing mode in the fluctuations before
+horizon crossing. However, dissipation intrinsically means departures from
+equilibrium, and therefore the presence of a shear viscous pressure in the
+radiation fluid. This in turn acts as an extra friction term for the radiation
+fluctuations that tends to damp the growth of the perturbations. Independently
+of the T functional dependence of the dissipation and the shear viscosity, we
+find that when the shear viscous coefficient \zeta_s is larger than 3 \rho_r/H
+at horizon crossing, \rho_r being the radiation energy density, the shear
+damping effect wins and there is no growing mode in the spectrum.",1106.0701v1
+2012-07-18,Attractiveness of periodic orbits in parametrically forced systemswith time-increasing friction,"We consider dissipative one-dimensional systems subject to a periodic force
+and study numerically how a time-varying friction affects the dynamics. As a
+model system, particularly suited for numerical analysis, we investigate the
+driven cubic oscillator in the presence of friction. We find that, if the
+damping coefficient increases in time up to a final constant value, then the
+basins of attraction of the leading resonances are larger than they would have
+been if the coefficient had been fixed at that value since the beginning. From
+a quantitative point of view, the scenario depends both on the final value and
+the growth rate of the damping coefficient. The relevance of the results for
+the spin-orbit model are discussed in some detail.",1207.4319v1
+2016-09-30,Origin of the effective mobility in non-linear active micro-rheology,"The distinction between the damping coefficient and the effective non-linear
+mobility of driven particles in active micro-rheology of supercooled liquids is
+explained in terms of individual and collective dynamics. The effective
+mobility arises as a collective effect which gives insight into the energy
+landscape of the system. On the other hand, the damping coefficient is a
+constant that modulates the effect of external forces over the thermal energy
+which particles have at their disposition to perform Brownian motion. For long
+times, these thermal fluctuations become characterized in terms of an effective
+temperature that is a consequence of the dynamic coupling between kinetic and
+configurational degrees of freedom induced by the presence of the strong
+external force. The interplay between collective mobility and effective
+temperature allows to formulate a generalized Stokes-Einstein relation that may
+be used to determine the collective diffusion coefficient. The explicit
+relations we deduce reproduce simulation data remarkably well.",1609.09853v1
+2017-04-24,Quasilinear diffusion coefficients in a finite Larmor radius expansion for ion cyclotron heated plasmas,"In this paper, a reduced model of quasilinear diffusion by a small Larmor
+radius approximation is derived to couple the Maxwell's equations and the
+Fokker-Planck equation self-consistently for ion cyclotron range of frequency
+waves in a tokamak. The reduced model ensures the important properties of the
+full model by Kennel-Engelmann diffusion, such as diffusion directions, wave
+polarizations, and H-theorem. The kinetic energy change (W-dot) is used to
+derive the reduced model diffusion coefficients for the fundamental damping and
+the second harmonic damping to the lowest order of the finite Larmor radius
+expansion. The quasilinear diffusion coefficients are implemented in a coupled
+code (TORIC-CQL3D) with the equivalent reduced model of dielectric tensor. We
+also present the simulations of the ITER minority heating scenario, in which
+the reduced model is verified within the allowable errors from the full model
+results.",1704.07283v1
+2017-04-19,Refractive index of dense materials,"We show that applying the Lorentz-Lorenz transformation to the refractive
+index of metals, semiconductors and insulators allows for a less empirical
+modeling of this refractive index.",1704.05718v1
+1998-10-01,Finite temperature dynamics of vortices in the two dimensional anisotropic Heisenberg model,"We study the effects of finite temperature on the dynamics of non-planar
+vortices in the classical, two-dimensional anisotropic Heisenberg model with
+XY- or easy-plane symmetry. To this end, we analyze a generalized
+Landau-Lifshitz equation including additive white noise and Gilbert damping.
+Using a collective variable theory with no adjustable parameters we derive an
+equation of motion for the vortices with stochastic forces which are shown to
+represent white noise with an effective diffusion constant linearly dependent
+on temperature. We solve these stochastic equations of motion by means of a
+Green's function formalism and obtain the mean vortex trajectory and its
+variance. We find a non-standard time dependence for the variance of the
+components perpendicular to the driving force. We compare the analytical
+results with Langevin dynamics simulations and find a good agreement up to
+temperatures of the order of 25% of the Kosterlitz-Thouless transition
+temperature. Finally, we discuss the reasons why our approach is not
+appropriate for higher temperatures as well as the discreteness effects
+observed in the numerical simulations.",9810011v1
+2004-07-21,A selfconsistent theory of current-induced switching of magnetization,"A selfconsistent theory of the current-induced switching of magnetization
+using nonequilibrium Keldysh formalism is developed for a junction of two
+ferromagnets separated by a nonmagnetic spacer. It is shown that the
+spin-transfer torques responsible for current-induced switching of
+magnetization can be calculated from first principles in a steady state when
+the magnetization of the switching magnet is stationary. The spin-transfer
+torque is expressed in terms of one-electron surface Green functions for the
+junction cut into two independent parts by a cleavage plane immediately to the
+left and right of the switching magnet. The surface Green functions are
+calculated using a tight-binding Hamiltonian with parameters determined from a
+fit to an {\it ab initio} band structure.This treatment yields the spin
+transfer torques taking into account rigorously contributions from all the
+parts of the junction. To calculate the hysteresis loops of resistance versus
+current, and hence to determine the critical current for switching, the
+microscopically calculated spin-transfer torques are used as an input into the
+phenomenological Landau-Lifshitz equation with Gilbert damping. The present
+calculations for Co/Cu/Co(111) show that the critical current for switching is
+$\approx 10^7A/cm^2$, which is in good agreement with experiment.",0407562v2
+2006-02-24,Magnetization dynamics in dysprosium orthoferrites via inverse Faraday effect,"The ultrafast non-thermal control of magnetization has recently become
+feasible in canted antiferromagnets through photomagnetic instantaneous pulses
+[A.V. Kimel {\it et al.}, Nature {\bf 435}, 655 (2005)]. In this experiment
+circularly polarized femtosecond laser pulses set up a strong magnetic field
+along the wave vector of the radiation through the inverse Faraday effect,
+thereby exciting non-thermally the spin dynamics of dysprosium orthoferrites. A
+theoretical study is performed by using a model for orthoferrites based on a
+general form of free energy whose parameters are extracted from experimental
+measurements. The magnetization dynamics is described by solving coupled
+sublattice Landau-Lifshitz-Gilbert equations whose damping term is associated
+with the scattering rate due to magnon-magnon interaction. Due to the inverse
+Faraday effect and the non-thermal excitation, the effect of the laser is
+simulated by magnetic field Gaussian pulses with temporal width of the order of
+hundred femtoseconds. When the field is along the z-axis, a single resonance
+mode of the magnetization is excited. The amplitude of the magnetization and
+out-of-phase behavior of the oscillations for fields in z and -z directions are
+in good agreement with the cited experiment. The analysis of the effect of the
+temperature shows that magnon-magnon scattering mechanism affects the decay of
+the oscillations on the picosecond scale. Finally, when the field pulse is
+along the x-axis, another mode is excited, as observed in experiments. In this
+case the comparison between theoretical and experimental results shows some
+discrepancies whose origin is related to the role played by anisotropies in
+orthoferrites.",0602593v1
+2006-04-19,"Stress - and Magneto-Impedance in Co71-xFexCr7Si8B14 (x = 0, 2) amorphous ribbons","Systematic measurements of stress impedance (SI) and magneto-impedance (MI)
+have been carried out using Co-rich amorphous ribbons of nominal composition
+Co71-xFexCr7Si8B14 (x = 0, 2) at various excitation frequencies and bias fields
+and at room temperature. The impedance, Z, for both the samples was found to be
+very sensitive functions of applied tensile stress (up to 100MPa) exhibiting a
+maximum SI ratio as much as 80% at low frequency ~ 0.1MHz. The nature of
+variation of impedance, Z, changes with the excitation frequency especially at
+higher frequencies in MHz region where it exhibits a peak. Magnetization
+measurements were also performed to observe the effects of applied stress and
+magnetization decreases with the application of stress confirming the negative
+magnetostriction co-efficient of both the samples. Both the samples exhibited
+negative magneto-impedance when the variation of Z is observed with the applied
+bias magnetic field, H. Maximum MI ratio as large as 99% has been observed for
+both the samples at low fields ~ 27Oe. The impedance as functions of applied
+magnetic field, Z(H), decreases with the application of stress thus making the
+MI curves broader. Based on the electromagnetic screening and magnetization
+dynamics and incorporating the Gilbert and the Bloch-Bloembergen damping and
+stress dependent anisotropy, the SI has been calculated and is found to
+describe well the stress and field dependence of impedance of the two samples.",0604438v2
+2010-05-25,"Structural, static and dynamic magnetic properties of CoMnGe thin films on a sapphire a-plane substrate","Magnetic properties of CoMnGe thin films of different thicknesses (13, 34,
+55, 83, 100 and 200 nm), grown by RF sputtering at 400{\deg}C on single crystal
+sapphire substrates, were studied using vibrating sample magnetometry (VSM) and
+conventional or micro-strip line (MS) ferromagnetic resonance (FMR). Their
+behavior is described assuming a magnetic energy density showing twofold and
+fourfold in-plane anisotropies with some misalignment between their principal
+directions. For all the samples, the easy axis of the fourfold anisotropy is
+parallel to the c-axis of the substrate while the direction of the twofold
+anisotropy easy axis varies from sample to sample and seems to be strongly
+influenced by the growth conditions. Its direction is most probably monitored
+by the slight unavoidable angle of miscut the Al2O3 substrate. The twofold
+in-plane anisotropy field is almost temperature independent, in contrast with
+the fourfold field which is a decreasing function of the temperature. Finally,
+we study the frequency dependence of the observed line-width of the resonant
+mode and we conclude to a typical Gilbert damping constant of 0.0065 for the
+55-nm-thick film.",1005.4595v3
+2011-06-22,Effect of spin diffusion on current generated by spin motive force,"Spin motive force is a spin-dependent force on conduction electrons induced
+by magnetization dynamics. In order to examine its effects on magnetization
+dynamics, it is indispensable to take into account spin accumulation, spin
+diffusion, and spin-flip scattering since the spin motive force is in general
+nonuniform. We examine the effects of all these on the way the spin motive
+force generates the charge and spin currents in conventional situations, where
+the conduction electron spin relaxation dynamics is much faster than the
+magnetization dynamics. When the spin-dependent electric field is spatially
+localized, which is common in experimental situations, we find that the
+conservative part of the spin motive force is unable to generate the charge
+current due to the cancelation effect by the diffusion current. We also find
+that the spin current is a nonlocal function of the spin motive force and can
+be effectively expressed in terms of nonlocal Gilbert damping tensor. It turns
+out that any spin independent potential such as Coulomb potential does not
+affect our principal results. At the last part of this paper, we apply our
+theory to current-induced domain wall motion.",1106.4389v2
+2011-07-11,Spin and charge transport induced by gauge fields in a ferromagnet,"We present a microscopic theory of spin-dependent motive force (""spin motive
+force"") induced by magnetization dynamics in a conducting ferromagnet, by
+taking account of spin relaxation of conduction electrons. The theory is
+developed by calculating spin and charge transport driven by two kinds of gauge
+fields; one is the ordinary electromagnetic field $A^{\rm em}_{\mu}$, and the
+other is the effective gauge field $A^{z}_{\mu}$ induced by dynamical magnetic
+texture. The latter acts in the spin channel and gives rise to a spin motive
+force. It is found that the current induced as a linear response to
+$A^{z}_{\mu}$ is not gauge-invariant in the presence of spin-flip processes.
+This fact is intimately related to the non-conservation of spin via Onsager
+reciprocity, so is robust, but indicates a theoretical inconsistency. This
+problem is resolved by considering the time dependence of spin-relaxation
+source terms in the ""rotated frame"", as in the previous study on Gilbert
+damping [J. Phys. Soc. Jpn. {\bf 76}, 063710 (2007)]. This effect restores the
+gauge invariance while keeping spin non-conservation. It also gives a
+dissipative spin motive force expected as a reciprocal to the dissipative spin
+torque (""$\beta$-term"").",1107.2165v3
+2012-07-02,"Establishing micromagnetic parameters of ferromagnetic semiconductor (Ga,Mn)As","(Ga,Mn)As is at the forefront of research exploring the synergy of magnetism
+with the physics and technology of semiconductors, and has led to discoveries
+of new spin-dependent phenomena and functionalities applicable to a wide range
+of material systems. Its recognition and utility as an ideal model material for
+spintronics research has been undermined by the large scatter in reported
+semiconducting doping trends and micromagnetic parameters. In this paper we
+establish these basic material characteristics by individually optimizing the
+highly non-equilibrium synthesis for each Mn-doping level and by simultaneously
+determining all micromagnetic parameters from one set of magneto-optical
+pump-and-probe measurements. Our (Ga,Mn)As thin-film epilayers, spannig the
+wide range of accessible dopings, have sharp thermodynamic Curie point
+singularities typical of uniform magnetic systems. The materials show
+systematic trends of increasing magnetization, carrier density, and Curie
+temperature (reaching 188 K) with increasing doping, and monotonous doping
+dependence of the Gilbert damping constant of ~0.1-0.01 and the spin stiffness
+of ~2-3 meVnm^2. These results render (Ga,Mn)As well controlled degenerate
+semiconductor with basic magnetic characteristics comparable to common band
+ferromagnets.",1207.0310v1
+2013-03-14,Spin-torque effects in thermally assisted magnetization reversal: Method of statistical moments,"Thermal fluctuations of nanomagnets driven by spin-polarized currents are
+treated via the Landau-Lifshitz-Gilbert equation generalized to include both
+the random thermal noise field and the Slonczewski spin-transfer torque term.
+By averaging this stochastic (Langevin) equation over its realizations, the
+explicit infinite hierarchy of differential-recurrence relations for
+statistical moments (averaged spherical harmonics) is derived for arbitrary
+demagnetizing factors and magnetocrystalline anisotropy for the generic
+nanopillar model of a spin-torque device comprising two ferromagnetic strata
+representing the free and fixed layers and a nonmagnetic conducting spacer all
+sandwiched between two ohmic contacts. The influence of thermal fluctuations
+and spin-transfer torques on relevant switching characteristics, such as the
+stationary magnetization, the magnetization reversal time, etc., is calculated
+by solving the hierarchy for wide ranges of temperature, damping, external
+magnetic field, and spin-polarized current indicating new spin-torque effects
+in the thermally assisted magnetization reversal comprising several orders of
+magnitude. In particular, a pronounced dependence of the switching
+characteristics on the directions of the external magnetic field and the spin
+polarization exists.",1303.3476v4
+2013-06-19,"Asymmetric Ferromagnetic Resonance, Universal Walker Breakdown, and Counterflow Domain Wall Motion in the Presence of Multiple Spin-Orbit Torques","We study the motion of several types of domain wall profiles in spin-orbit
+coupled magnetic nanowires and also the influence of spin-orbit interaction on
+the ferromagnetic resonance of uniform magnetic films. We extend previous
+studies by fully considering not only the field-like contribution from the
+spin-orbit torque, but also the recently derived Slonczewski-like spin-orbit
+torque. We show that the latter interaction affects both the domain wall
+velocity and the Walker breakdown threshold non-trivially, which suggests that
+it should be accounted in experimental data analysis. We find that the presence
+of multiple spin-orbit torques may render the Walker breakdown to be universal
+in the sense that the threshold is completely independent on the
+material-dependent Gilbert damping, non-adiabaticity, and the chirality of the
+domain wall. We also find that domain wall motion against the current injection
+is sustained in the presence of multiple spin-orbit torques and that the wall
+profile will determine the qualitative influence of these different types of
+torques (e.g. field-like and Slonczewski-like). In addition, we consider a
+uniform ferromagnetic layer under a current bias, and find that the resonance
+frequency becomes asymmetric against the current direction in the presence of
+Slonczewski-like spin-orbit coupling. This is in contrast with those cases
+where such an interaction is absent, where the frequency is found to be
+symmetric with respect to the current direction. This finding shows that
+spin-orbit interactions may offer additional control over pumped and absorbed
+energy in a ferromagnetic resonance setup by manipulating the injected current
+direction.",1306.4680v1
+2013-11-29,Magnon radiation by moving Abrikosov vortices in ferromagnetic superconductors and superconductor-ferromagnet multilayers,"In systems combining type-II superconductivity and magnetism the
+non-stationary magnetic field of moving Abrikosov vortices may excite spin
+waves, or magnons. This effect leads to the appearance of an additional damping
+force acting on the vortices. By solving the London and Landau-Lifshitz-Gilbert
+equations we calculate the magnetic moment induced force acting on vortices in
+ferromagnetic superconductors and superconductor/ferromagnet superlattices. If
+the vortices are driven by a dc force, magnon generation due to the Cherenkov
+resonance starts as the vortex velocity exceeds some threshold value. For an
+ideal vortex lattice this leads to an anisotropic contribution to the
+resistivity and to the appearance of resonance peaks on the current voltage
+characteristics. For a disordered vortex array the current will exhibit a
+step-like increase at some critical voltage. If the vortices are driven by an
+ac force with a frequency \omega, the interaction with magnetic moments will
+lead to a frequency-dependent magnetic contribution \eta_M to the vortex
+viscosity. If \omega is below the ferromagnetic resonance frequency \omega_F,
+vortices acquire additional inertia. For \omega > \omega_F dissipation is
+enhanced due to magnon generation. The viscosity \eta_M can be extracted from
+the surface impedance of the ferromagnetic superconductor. Estimates of the
+magnetic force acting on vortices for the U-based ferromagnetic superconductors
+and cuprate/manganite superlattices are given.",1311.7620v1
+2014-03-03,Observations and Implications of Large-Amplitude Longitudinal Oscillations in a Solar Filament,"On 20 August 2010 an energetic disturbance triggered large-amplitude
+longitudinal oscillations in a nearby filament. The triggering mechanism
+appears to be episodic jets connecting the energetic event with the filament
+threads. In the present work we analyze this periodic motion in a large
+fraction of the filament to characterize the underlying physics of the
+oscillation as well as the filament properties. The results support our
+previous theoretical conclusions that the restoring force of large-amplitude
+longitudinal oscillations is solar gravity, and the damping mechanism is the
+ongoing accumulation of mass onto the oscillating threads. Based on our
+previous work, we used the fitted parameters to determine the magnitude and
+radius of curvature of the dipped magnetic field along the filament, as well as
+the mass accretion rate onto the filament threads. These derived properties are
+nearly uniform along the filament, indicating a remarkable degree of
+cohesiveness throughout the filament channel. Moreover, the estimated mass
+accretion rate implies that the footpoint heating responsible for the thread
+formation, according to the thermal nonequilibrium model, agrees with previous
+coronal heating estimates. We estimate the magnitude of the energy released in
+the nearby event by studying the dynamic response of the filament threads, and
+discuss the implications of our study for filament structure and heating.",1403.0381v1
+2015-01-16,Direct measurement of the magnetic anisotropy field in Mn--Ga and Mn--Co--Ga Heusler films,"The static and dynamic magnetic properties of tetragonally distorted Mn--Ga
+based alloys were investigated. Static properties are determined in magnetic
+fields up to 6.5~T using SQUID magnetometry. For the pure Mn$_{1.6}$Ga film,
+the saturation magnetisation is 0.36~MA/m and the coercivity is 0.29~T. Partial
+substitution of Mn by Co results in Mn$_{2.6}$Co$_{0.3}$Ga$_{1.1}$. The
+saturation magnetisation of those films drops to 0.2~MA/m and the coercivity is
+increased to 1~T.
+  Time-resolved magneto-optical Kerr effect (TR-MOKE) is used to probe the
+high-frequency dynamics of Mn--Ga. The ferromagnetic resonance frequency
+extrapolated to zero-field is found to be 125~GHz with a Gilbert damping,
+$\alpha$, of 0.019. The anisotropy field is determined from both SQUID and
+TR-MOKE to be 4.5~T, corresponding to an effective anisotropy density of
+0.81~MJ/m$^3$.
+  Given the large anisotropy field of the Mn$_{2.6}$Co$_{0.3}$Ga$_{1.1}$ film,
+pulsed magnetic fields up to 60~T are used to determine the field strength
+required to saturate the film in the plane. For this, the extraordinary Hall
+effect was employed as a probe of the local magnetisation. By integrating the
+reconstructed in--plane magnetisation curve, the effective anisotropy energy
+density for Mn$_{2.6}$Co$_{0.3}$Ga$_{1.1}$ is determined to be 1.23~MJ/m$^3$.",1501.03973v1
+2015-06-02,Respective influence of in-plane and out-of-plane spin-transfer torques in magnetization switching of perpendicular magnetic tunnel junctions,"The relative contributions of in-plane (damping-like) and out-of-plane
+(field-like) spin-transfer-torques in the magnetization switching of
+out-of-plane magnetized magnetic tunnel junctions (pMTJ) has been theoretically
+analyzed using the transformed Landau-Lifshitz (LL) equation with the STT
+terms. It is demonstrated that in a pMTJ structure obeying macrospin dynamics,
+the out-of-plane torque influences the precession frequency but it does not
+contribute significantly to the STT switching process (in particular to the
+switching time and switching current density), which is mostly determined by
+the in-plane STT contribution. This conclusion is confirmed by finite
+temperature and finite writing pulse macrospin simulations of the current-field
+switching diagrams. It contrasts with the case of STT-switching in in-plane
+magnetized MTJ in which the field-like term also influences the switching
+critical current. This theoretical analysis was successfully applied to the
+interpretation of voltage-field STT switching diagrams experimentally measured
+on perpendicular MTJ pillars 36 nm in diameter, which exhibit macrospin-like
+behavior. The physical nonequivalence of Landau and Gilbert dissipation terms
+in presence of STT-induced dynamics is also discussed.",1506.00780v2
+2015-08-28,Control of magnetic relaxation by electric-field-induced ferroelectric phase transition and inhomogeneous domain switching,"Electric-field modulation of magnetism in strain-mediated multiferroic
+heterostructures is considered a promising scheme for enabling memory and
+magnetic microwave devices with ultralow power consumption. However, it is not
+well understood how electric-field-induced strain influences magnetic
+relaxation, an important physical process for device applications. Here we
+investigate resonant magnetization dynamics in ferromagnet/ferrolectric
+multiferroic heterostructures, FeGaB/PMN-PT and NiFe/PMN-PT, in two distinct
+strain states provided by electric-field-induced ferroelectric phase
+transition. The strain not only modifies magnetic anisotropy but also magnetic
+relaxation. In FeGaB/PMN-PT, we observe a nearly two-fold change in intrinsic
+Gilbert damping by electric field, which is attributed to strain-induced tuning
+of spin-orbit coupling. By contrast, a small but measurable change in extrinsic
+linewidth broadening is attributed to inhomogeneous ferroelastic domain
+switching during the phase transition of the PMN-PT substrate.",1508.07290v2
+2016-04-05,Homodyne-detected ferromagnetic resonance of in-plane magnetized nano-contacts: composite spin wave resonances and their excitation mechanism,"This work provides a detailed investigation of the measured in-plane
+field-swept homodyne-detected ferromagnetic resonance (FMR) spectra of an
+extended Co/Cu/NiFe pseudo spin valve stack using a nanocontact (NC) geometry.
+The magnetodynamics are generated by a pulse-modulated microwave current and
+the resulting rectified dc mixing voltage, which appears across the NC at
+resonance, is detected using a lock-in amplifier. Most notably, we find that
+the measured spectra of the NiFe layer are composite in nature and highly
+asymmetric, consistent with the broadband excitation of multiple modes.
+Additionally, the data must be fit with two Lorentzian functions in order to
+extract a reasonable value for the Gilbert damping of the NiFe. Aided by
+micromagnetic simulations, we conclude that (i) for in-plane fields the rf
+Oersted field in the vicinity of the NC plays the dominant role in generating
+the observed spectra, (ii) in addition to the FMR mode, exchange dominated spin
+waves are also generated, and (iii) the NC diameter sets the mean wavevector of
+the exchange dominated spin wave, in good agreement with the dispersion
+relation.",1604.01389v1
+2017-01-10,Motion of skyrmions in nanowires driven by magnonic momentum-transfer forces,"We study the motion of magnetic skyrmions in a nanowire induced by a
+spin-wave current $J$ flowing out of a driving layer close to the edge of the
+wire. By applying micromagnetic simulation and an analysis of the effective
+Thiele equation, we find that the skyrmion trajectory is governed by an
+interplay of both forces due to the magnon current and the wire boundary. The
+skyrmion is attracted to the driving layer and is accelerated by the repulsive
+force due to the wire boundary. We consider both cases of a driving
+longitudinal and transverse to the nanowire, but a steady-state motion of the
+skyrmion is only obtained for a transverse magnon current. For the latter case,
+we find in the limit of low current densities $J$ the velocity-current relation
+$v \sim J/\alpha$ where $v$ is the skyrmion velocity and $\alpha$ is the
+Gilbert damping. For large $J$ in case of strong driving, the skyrmion is
+pushed into the driving layer resulting in a drop of the skyrmion velocity and,
+eventually, the destruction of the skyrmion.",1701.02430v2
+2017-01-19,Ultrafast Electron-Lattice Coupling Dynamics in VO2 and V2O3 Thin Films,"Ultrafast optical pump - optical probe and optical pump - terahertz probe
+spectroscopy were performed on vanadium dioxide (VO2) and vanadium sesquioxide
+(V2O3) thin films over a wide temperature range. A comparison of the
+experimental data from these two different techniques and two different
+vanadium oxides, in particular a comparison of the electronic oscillations
+generated by the photoinduced longitudinal acoustic modulation, reveals the
+strong electron-phonon coupling that exists in the metallic state of both
+materials. The low energy Drude response of V2O3 appears more susceptible than
+VO2 to ultrafast strain control. Additionally, our results provide a
+measurement of the temperature dependence of the sound velocity in both
+systems, revealing a four- to fivefold increase in VO2 and a three- to fivefold
+increase in V2O3 across the phase transition. Our data also confirm
+observations of strong damping and phonon anharmonicity in the metallic phase
+of VO2, and suggest that a similar phenomenon might be at play in the metallic
+phase of V2O3. More generally, our simple table-top approach provides relevant
+and detailed information about dynamical lattice properties of vanadium oxides,
+opening the way to similar studies in other complex materials.",1701.05531v1
+2017-02-21,All-optical Detection of Spin Hall Angle in W/CoFeB/SiO2 Heterostructures by Varying Tungsten Layer Thickness,"The development of advanced spintronics devices hinges on the efficient
+generation and utilization of pure spin current. In materials with large
+spin-orbit coupling, the spin Hall effect may convert charge current to pure
+spin current and a large conversion efficiency, which is quantified by spin
+Hall angle (SHA), is desirable for the realization of miniaturized and energy
+efficient spintronic devices. Here, we report a giant SHA in beta-tungsten
+(\b{eta}-W) thin films in Sub/W(t)/Co20Fe60B20(3 nm)/SiO2(2 nm)
+heterostructures with variable W thickness. We employed an all-optical
+time-resolved magneto-optical Kerr effect microscope for an unambiguous
+determination of SHA using the principle of modulation of Gilbert damping of
+the adjacent ferromagnetic layer by the spin-orbit torque from the W layer. A
+non-monotonic variation of SHA with W layer thickness (t) is observed with a
+maximum of about 0.4 at about t = 3 nm, followed by a sudden reduction to a
+very low value at t = 6 nm. This variation of SHA with W-thickness correlates
+well with the thickness dependent structural phase transition and resistivity
+variation of W above the spin diffusion length of W, while below this length
+the interfacial electronic effect at W/CoFeB influences the estimation of SHA.",1702.06258v1
+2017-03-21,Annealing stability of magnetic tunnel junctions based on dual MgO free layers and [Co/Ni] based thin synthetic antiferromagnet fixed system,"We study the annealing stability of bottom-pinned perpendicularly magnetized
+magnetic tunnel junctions based on dual MgO free layers and thin fixed systems
+comprising a hard [Co/Ni] multilayer antiferromagnetically coupled to thin a Co
+reference layer and a FeCoB polarizing layer. Using conventional magnetometry
+and advanced broadband ferromagnetic resonance, we identify the properties of
+each sub-unit of the magnetic tunnel junction and demonstrate that this
+material option can ensure a satisfactory resilience to the 400$^\circ$C
+thermal annealing needed in solid-state magnetic memory applications. The dual
+MgO free layer possesses an anneal-robust 0.4 T effective anisotropy and
+suffers only a minor increase of its Gilbert damping from 0.007 to 0.010 for
+the toughest annealing conditions. Within the fixed system, the ferro-coupler
+and texture-breaking TaFeCoB layer keeps an interlayer exchange above 0.8
+mJ/m$^2$, while the Ru antiferrocoupler layer within the synthetic
+antiferromagnet maintains a coupling above -0.5 mJ/m$^2$. These two strong
+couplings maintain the overall functionality of the tunnel junction upon the
+toughest annealing despite the gradual degradation of the thin Co layer
+anisotropy that may reduce the operation margin in spin torque memory
+applications. Based on these findings, we propose further optimization routes
+for the next generation magnetic tunnel junctions.",1703.07154v1
+2017-08-03,Evolution of the interfacial perpendicular magnetic anisotropy constant of the Co$_2$FeAl/MgO interface upon annealing,"We investigate thickness series of films of the Heusler alloy Co$_2$FeAl in
+order to study the effect of annealing on the interface with a MgO layer and on
+the bulk magnetic properties. Our results reveal that while the perpendicular
+interface anisotropy constant $K^{\perp}_{\rm S}$ is zero for the as-deposited
+samples, its value increases with annealing up to a value of $1.14\, \pm
+\,0.07$~mJ/m$^2$ for the series annealed at 320$^{\rm o}$C and of $2.07\, \pm
+\,0.7$~mJ/m$^2$ for the 450$^{\rm o}$C annealed series owing to a strong
+modification of the interface during the thermal treatment. This large value
+ensures a stabilization of a perpendicular magnetization orientation for a
+thickness below 1.7~nm. The data additionally shows that the in-plane biaxial
+anisotropy constant has a different evolution with thickness in as-deposited
+and annealed systems. The Gilbert damping parameter $\alpha$ shows minima for
+all series for a thickness of 40~nm and an absolute minimum value of
+$2.8\pm0.1\cdot10^{-3}$. The thickness dependence is explained in terms of an
+inhomogenous magnetization state generated by the interplay between the
+different anisotropies of the system and by crystalline disorder.",1708.01126v2
+2017-08-08,Spin-orbit-torque driven magnetoimpedance in Pt-layer/magnetic-ribbon heterostructures,"When a flow of electron passes through a paramagnetic layer with strong
+spin-orbit-coupling such as platinum (Pt), a net spin current is produced via
+spin Hall effect (SHE). This spin current can exert a torque on the
+magnetization of an adjacent ferromagnetic layer which can be probed via
+magnetization dynamic response, e.g. spin-torque ferromagnetic resonance
+(ST-FMR). Nevertheless, that effect in lower frequency magnetization dynamic
+regime (MHz) where skin effect occurs in high permeability ferromagnetic
+conductors namely the magneto-impedance (MI) effect can be fundamentally
+important which has not been studied so far. Here, by utilizing the MI effect
+in magnetic-ribbon/Pt heterostructure with high magnetic permeability that
+allows the ac current effectively confined at the skin depth of ~100 nm
+thickness, the effect of spin-orbit-torque (SOT) induced by the SHE probed via
+MI measurement is investigated. We observed a systematic MI frequency shift
+that increases by increasing the applied current amplitude and thickness of the
+Pt layer (varying from 0 nm to 20 nm). In addition, the role of Pt layer in
+ribbon/Pt heterostructure is evaluated with ferromagnetic resonance (FMR)
+effect representing standard Gilbert damping increase as the result of presence
+of the SHE. Our results unveil the role of SOT in dynamic control of the
+transverse magnetic permeability probed with impedance spectroscopy as useful
+and valuable technique for detection of future SHE devices.",1708.02402v2
+2017-12-20,Second-harmonic magnetic response characterizing magnetite-based colloid,"Nonlinear second-harmonic magnetic response (M2) was used to characterize an
+aqueous colloidal solution of dextran-coated magnetite (Fe3O4) nanoparticles.
+Data analysis with the formalism based on Gilbert-Landau-Lifshitz equation for
+stochastic dynamics of superparamagnetic (SP) particles ensured extensive
+quantifying of the system via a set of magnetic and magnetodynamic parameters,
+such as the mean magnetic moment, the damping constant, the longitudinal
+relaxation time, the magnetic anisotropy field and energy, and others. Combined
+with transmission electron microscopy and dynamic light scattering, M2
+technique allowed obtaining additional parameters, viz., the dextran-coating
+thickness and the interparticle magnetic dipolar energy. Aggregated colloidal
+nanoparticles were shown to be magnetically correlated inside the aggregate due
+to magnetic dipole-dipole (d-d) coupling within the correlation radius ~50 nm.
+With the d-d coupling account, the volume distribution of the aggregates
+recovered from M2 measurements is well consistent with electron microscopy
+results. From electron magnetic resonance, abrupt change of SP dynamics with
+increasing external magnetic field was observed and explained. The presented
+study exemplifies a novel M2-based procedure of comprehensive quantitative
+characterization applicable for a wide variety of SP systems.",1712.07534v1
+2018-02-09,Monocrystalline free standing 3D yttrium iron garnet magnon nano resonators,"Nano resonators in which mechanical vibrations and spin waves can be coupled
+are an intriguing concept that can be used in quantum information processing to
+transfer information between different states of excitation. Until now, the
+fabrication of free standing magnetic nanostructures which host long lived spin
+wave excitatons and may be suitable as mechanical resonators seemed elusive. We
+demonstrate the fabrication of free standing monocrystalline yttrium iron
+garnet (YIG) 3D nanoresonators with nearly ideal magnetic properties. The
+freestanding 3D structures are obtained using a complex lithography process
+including room temperature deposition and lift-off of amorphous YIG and
+subsequent crystallization by annealing. The crystallization nucleates from the
+substrate and propagates across the structure even around bends over distances
+of several micrometers to form e.g. monocrystalline resonators as shown by
+transmission electron microscopy. Spin wave excitations in individual
+nanostructures are imaged by time resolved scanning Kerr microscopy. The narrow
+linewidth of the magnetic excitations indicates a Gilbert damping constant of
+only $\alpha = 2.6 \times 10^{-4}$ rivalling the best values obtained for
+epitaxial YIG thin film material. The new fabrication process represents a leap
+forward in magnonics and magnon mechanics as it provides 3D YIG structures of
+unprecedented quality. At the same time it demonstrates a completely new route
+towards the fabrication of free standing crystalline nano structures which may
+be applicable also to other material systems.",1802.03176v2
+2018-11-30,Dynamical precession of spin in the two-dimensional spin-orbit coupled systems,"We investigate the spin dynamics in the two-dimensional spin-orbit coupled
+system subject to an in-plane ($x$-$y$ plane) constant electric field, which is
+assumed to be turned on at the moment $t=0$. The equation of spin precession in
+linear response to the switch-on of the electric field is derived in terms of
+Heisenberg's equation by the perturbation method up to the first order of the
+electric field. The dissipative effect, which is responsible for bringing the
+dynamical response to an asymptotic result, is phenomenologically implemented
+\`{a} la the Landau-Lifshitz-Gilbert equation by introducing damping terms upon
+the equation of spin dynamics. Mediated by the dissipative effect, the
+resulting spin dynamics asymptotes to a stationary state, where the spin and
+the momentum-dependent effective magnetic field are aligned again and have
+nonzero components in the out-of-plane ($z$) direction. In the linear response
+regime, the asymptotic response obtained by the dynamical treatment is in full
+agreement with the stationary response as calculated in the Kubo formula, which
+is a time-independent approach treating the applied electric field as
+completely time-independent. Our method provides a new perspective on the
+connection between the dynamical and stationary responses.",1811.12626v2
+2019-03-08,Spin-transfer torques for domain walls in antiferromagnetically coupled ferrimagnets,"Antiferromagnetic materials are outstanding candidates for next generation
+spintronic applications, because their ultrafast spin dynamics makes it
+possible to realize several orders of magnitude higher-speed devices than
+conventional ferromagnetic materials1. Though spin-transfer torque (STT) is a
+key for electrical control of spins as successfully demonstrated in
+ferromagnetic spintronics, experimental understanding of STT in
+antiferromagnets has been still lacking despite a number of pertinent
+theoretical studies2-5. Here, we report experimental results on the effects of
+STT on domain-wall (DW) motion in antiferromagnetically-coupled ferrimagnets.
+We find that non-adiabatic STT acts like a staggered magnetic field and thus
+can drive DWs effectively. Moreover, the non-adiabaticity parameter {\beta} of
+STT is found to be significantly larger than the Gilbert damping parameter
+{\alpha}, challenging our conventional understanding of the non-adiabatic STT
+based on ferromagnets as well as leading to fast current-induced
+antiferromagnetic DW motion. Our study will lead to further vigorous
+exploration of STT for antiferromagnetic spin textures for fundamental physics
+on spin-charge interaction as wells for efficient electrical control of
+antiferromagnetic devices.",1903.03251v1
+2019-03-26,Engineering of spin mixing conductance in Ru/FeCo/Ru interfaces: Effect of Re Doping,"We have deposited polycrystalline Re doped $(Fe_{65}Co_{35})_{100-x}Re_{x}$
+(0 $\leq$ x $\leq$ 12.6 at\%) thin films grown under identical conditions and
+sandwiched between thin layers of Ru in order to study the phenomenon of spin
+pumping as a function of Re concentration. In-plane and out-of-plane
+ferromagnetic resonance spectroscopy results show an enhancement of the Gilbert
+damping with an increase in Re doping. We found evidence of an increase in the
+real part of effective spin mixing conductance
+[Re($g^{\uparrow\downarrow}_{eff}$)] with the increase in Re doping of 6.6
+at\%, while a decrease is evident at higher Re doping. The increase in
+Re($g^{\uparrow\downarrow}_{eff}$) can be linked to the Re doping induced
+change of the interface electronic structure in the non-magnetic Ru layer and
+the effect interfacial spin-orbit coupling has on the effective spin-mixing
+conductance. The lowest and highest values of
+Re($g^{\uparrow\downarrow}_{eff}$) are found to be 9.883(02) $nm^{-2}$ and
+19.697(02) $nm^{-2}$ for 0 at\% and 6.6 at\% Re doping, respectively. The
+saturation magnetization decreases with increasing Re doping, from 2.362(13) T
+for the undoped film to 1.740(03) T for 12.6 at\% Re doping. This study opens a
+new direction of tuning the spin-mixing conductance in magnetic
+heterostructures by doping of the ferromagnetic layerr, which is essential for
+the realization of energy efficient operation of spintronic devices.",1903.10966v2
+2019-12-16,Spin-current manipulation of photoinduced magnetization dynamics in heavy metal / ferromagnet double layer based nanostructures,"Spin currents offer a way to control static and dynamic magnetic properties,
+and therefore they are crucial for next-generation MRAM devices or spin-torque
+oscillators. Manipulating the dynamics is especially interesting within the
+context of photo-magnonics. In typical $3d$ transition metal ferromagnets like
+CoFeB, the lifetime of light-induced magnetization dynamics is restricted to
+about 1 ns, which e.g. strongly limits the opportunities to exploit the wave
+nature in a magnonic crystal filtering device. Here, we investigate the
+potential of spin-currents to increase the spin wave lifetime in a functional
+bilayer system, consisting of a heavy metal (8 nm of $\beta$-Tantalum
+(Platinum)) and 5 nm CoFeB. Due to the spin Hall effect, the heavy metal layer
+generates a transverse spin current when a lateral charge current passes
+through the strip. Using time-resolved all-optical pump-probe spectroscopy, we
+investigate how this spin current affects the magnetization dynamics in the
+adjacent CoFeB layer. We observed a linear spin current manipulation of the
+effective Gilbert damping parameter for the Kittel mode from which we were able
+to determine the system's spin Hall angles. Furthermore, we measured a strong
+influence of the spin current on a high-frequency mode. We interpret this mode
+an an exchange dominated higher order spin-wave resonance. Thus we infer a
+strong dependence of the exchange constant on the spin current.",1912.07728v1
+2020-01-09,Role of longitudinal fluctuations in L$1_0$ FePt,"L$1_0$ FePt is a technologically important material for a range of novel data
+storage applications. In the ordered FePt structure the normally non-magnetic
+Pt ion acquires a magnetic moment, which depends on the local field originating
+from the neighboring Fe atoms. In this work a model of FePt is constructed,
+where the induced Pt moment is simulated by using combined longitudinal and
+rotational spin dynamics. The model is parameterized to include a linear
+variation of the moment with the exchange field, so that at the Pt site the
+magnetic moment depends on the Fe ordering. The Curie temperature of FePt is
+calculated and agrees well with similar models that incorporate the Pt dynamics
+through an effective Fe-only Hamiltonian. By computing the dynamic correlation
+function the anisotropy field and the Gilbert damping are extracted over a
+range of temperatures. The anisotropy exhibits a power-law dependence with
+temperature with exponent $n\approx2.1$. This agrees well with what observed
+experimentally and it is obtained without including a two-ion anisotropy term
+as in other approaches. Our work shows that incorporating longitudinal
+fluctuations into spin dynamics calculations is crucial for understanding the
+properties of materials with induced moments.",2001.03074v1
+2020-05-07,Effect of interfacial oxidation layer in spin pumping experiments on Ni$_{80}$Fe$_{20}$/SrIrO$_3$ heterostructures,"SrIrO$_3$ with its large spin-orbit coupling and low charge conductivity has
+emerged as a potential candidate for efficient spin-orbit torque magnetization
+control in spintronic devices. We here report on the influence of an
+interfacial oxide layer on spin pumping experiments in Ni$_{80}$Fe$_{20}$
+(NiFe)/SrIrO$_3$ bilayer heterostructures. To investigate this scenario we have
+carried out broadband ferromagnetic resonance (BBFMR) measurements, which
+indicate the presence of an interfacial antiferromagnetic oxide layer. We
+performed in-plane BBFMR experiments at cryogenic temperatures, which allowed
+us to simultaneously study dynamic spin pumping properties (Gilbert damping)
+and static magnetic properties (such as the effective magnetization and
+magnetic anisotropy). The results for NiFe/SrIrO$_3$ bilayer thin films were
+analyzed and compared to those from a NiFe/NbN/SrIrO$_3$ trilayer reference
+sample, where a spin-transparent, ultra-thin NbN layer was inserted to prevent
+oxidation of NiFe. At low temperatures, we observe substantial differences in
+the magnetization dynamics parameters of these samples, which can be explained
+by an antiferromagnetic interfacial layer in the NiFe/SrIrO$_3$ bilayers.",2005.03727v1
+2020-05-28,Hard antinodal gap revealed by quantum oscillations in the pseudogap regime of underdoped high-$T_{\rm c}$ superconductors,"An understanding of the missing antinodal electronic excitations in the
+pseudogap state is essential for uncovering the physics of the underdoped
+cuprate high temperature superconductors. The majority of high temperature
+experiments performed thus far, however, have been unable to discern whether
+the antinodal states are rendered unobservable due to their damping, or whether
+they vanish due to their gapping. Here we distinguish between these two
+scenarios by using quantum oscillations to examine whether the small Fermi
+surface pocket, found to occupy only 2% of the Brillouin zone in the underdoped
+cuprates, exists in isolation against a majority of completely gapped density
+of states spanning the antinodes, or whether it is thermodynamically coupled to
+a background of ungapped antinodal states. We find that quantum oscillations
+associated with the small Fermi surface pocket exhibit a signature sawtooth
+waveform characteristic of an isolated two-dimensional Fermi surface pocket.
+This finding reveals that the antinodal states are destroyed by a hard gap that
+extends over the majority of the Brillouin zone, placing strong constraints on
+a drastic underlying origin of quasiparticle disappearance over almost the
+entire Brillouin zone in the pseudogap regime.",2005.14123v1
+2020-06-01,Enhancement in Thermally Generated Spin Voltage at Pd/NiFe$_2$O$_4$ Interfaces by the Growth on Lattice-Matched Substrates,"Efficient spin injection from epitaxial ferrimagnetic NiFe$_2$O$_4$ thin
+films into a Pd layer is demonstrated via spin Seebeck effect measurements in
+the longitudinal geometry. The NiFe$_2$O$_4$ films (60 nm to 1 $\mu$m) are
+grown by pulsed laser deposition on isostructural spinel MgAl$_2$O$_4$,
+MgGa$_2$O$_4$, and CoGa$_2$O$_4$ substrates with lattice mismatch varying
+between 3.2% and 0.2%. For the thinner films ($\leq$ 330 nm), an increase in
+the spin Seebeck voltage is observed with decreasing lattice mismatch, which
+correlates well with a decrease in the Gilbert damping parameter as determined
+from ferromagnetic resonance measurements. High resolution transmission
+electron microscopy studies indicate substantial decrease of antiphase boundary
+and interface defects that cause strain-relaxation, i.e., misfit dislocations,
+in the films with decreasing lattice mismatch. This highlights the importance
+of reducing structural defects in spinel ferrites for efficient spin injection.
+It is further shown that angle-dependent spin Seebeck effect measurements
+provide a qualitative method to probe for in-plane magnetic anisotropies
+present in the films.",2006.00777v1
+2020-06-10,Study of magnetic interface and its effect in Fe/NiFe bilayers of alternating order,"We present a comprehensive study on the magnetization reversal in Fe/NiFe
+bilayer system by alternating the order of the magnetic layers. All the samples
+show growth-induced uniaxial magnetic anisotropy due to oblique angle
+deposition technique. Strong interfacial exchange coupling between the Fe and
+NiFe layers leads to the single-phase hysteresis loops in the bilayer system.
+The strength of coupling being dependent on the interface changes upon
+alternating the order of magnetic layers. The magnetic parameters such as
+coercivity HC, and anisotropy field HK become almost doubled when NiFe layer is
+grown over the Fe layers. This enhancement in the magnetic parameters is
+primarily dependent on the increase of the thickness and magnetic moment of
+Fe-NiFe interfacial layer as revealed from the polarized neutron reectivity
+(PNR) data of the bilayer samples. The difference in the thickness and
+magnetization of the Fe-NiFe interfacial layer indicates the modification of
+the microstructure by alternating the order of the magnetic layers of the
+bilayers. The interfacial magnetic moment increased by almost 18 % when NiFe
+layer is grown over the Fe layer. In spite of the different values of
+anisotropy fields and modified interfacial exchange coupling, the Gilbert
+damping constant values of the ferromagnetic bilayers remain similar to single
+NiFe layer.",2006.05756v1
+2020-09-07,Spin pumping in d-wave superconductor/ferromagnet hybrids,"Spin-pumping across ferromagnet/superconductor (F/S) interfaces has attracted
+much attention lately. Yet the focus has been mainly on s-wave
+superconductors-based systems whereas (high-temperature) d-wave superconductors
+such as YBa2Cu3O7-d (YBCO) have received scarce attention despite their
+fundamental and technological interest. Here we use wideband ferromagnetic
+resonance to study spin-pumping effects in bilayers that combine a soft
+metallic Ni80Fe20 (Py) ferromagnet and YBCO. We evaluate the spin conductance
+in YBCO by analyzing the magnetization dynamics in Py. We find that the Gilbert
+damping exhibits a drastic drop as the heterostructures are cooled across the
+normal-superconducting transition and then, depending on the S/F interface
+morphology, either stays constant or shows a strong upturn. This unique
+behavior is explained considering quasiparticle density of states at the YBCO
+surface, and is a direct consequence of zero-gap nodes for particular
+directions in the momentum space. Besides showing the fingerprint of d-wave
+superconductivity in spin-pumping, our results demonstrate the potential of
+high-temperature superconductors for fine tuning of the magnetization dynamics
+in ferromagnets using k-space degrees of freedom of d-wave/F interfaces.",2009.03196v3
+2020-10-17,Multiscale modelling of magnetostatic effects on magnetic nanoparticles with application to hyperthermia,"We extend a renormalization group-based course-graining method for
+micromagnetic simulations to include properly scaled magnetostatic
+interactions. We apply the method in simulations of dynamic hysteresis loops at
+clinically relevant sweep rates and at 310 K of iron oxide nanoparticles (NPs)
+of the kind that have been used in preclinical studies of magnetic
+hyperthermia. The coarse-graining method, along with a time scaling involving
+sweep rate and Gilbert damping parameter, allow us to span length scales from
+the unit cell to NPs approximately 50 nm in diameter with reasonable simulation
+times. For both NPs and the nanorods composing them, we report effective
+uniaxial anisotropy strengths and saturation magnetizations, which differ from
+those of the bulk materials magnetite and maghemite of which they are made, on
+account of the combined non-trivial effects of temperature, inter-rod exchange,
+magnetostatic interactions and the degree of orientational order within the
+nanorod composites. The effective parameters allow treating the NPs as single
+macrospins, and we find for the test case of calculating loops for two aligned
+NPs that using the dipole approximation is sufficient for distances beyond 1.5
+times the NP diameter. We also present a study on relating integration time
+step to micromagnetic cell size, finding that the optimal time step size scales
+approximately linearly with cell volume.",2010.08848v1
+2021-02-09,Unconventional quantum vortex matter state hosts quantum oscillations in the underdoped high-temperature cuprate superconductors,"A central question in the underdoped cuprates pertains to the nature of the
+pseudogap ground state. A conventional metallic ground state of the pseudogap
+region has been argued to host quantum oscillations upon destruction of the
+superconducting order parameter by modest magnetic fields. Here we use low
+applied measurement currents and millikelvin temperatures on ultra-pure single
+crystals of underdoped YBa$_2$Cu$_3$O$_{6+x}$ to unearth an unconventional
+quantum vortex matter ground state characterized by vanishing electrical
+resistivity, magnetic hysteresis, and non-ohmic electrical transport
+characteristics beyond the highest laboratory accessible static fields. A new
+model of the pseudogap ground state is now required to explain quantum
+oscillations that are hosted by the bulk quantum vortex matter state without
+experiencing sizeable additional damping in the presence of a large maximum
+superconducting gap; possibilities include a pair density wave.",2102.04927v2
+2021-03-11,Long-range spin transport on the surface of topological Dirac semimetal,"We theoretically propose the long-range spin transport mediated by the
+gapless surface states of topological Dirac semimetal (TDSM). Low-dissipation
+spin current is a building block of next-generation spintronics devices. While
+conduction electrons in metals and spin waves in ferromagnetic insulators
+(FMIs) are the major carriers of spin current, their propagation length is
+inevitably limited due to the Joule heating or the Gilbert damping. In order to
+suppress dissipation and realize long-range spin transport, we here make use of
+the spin-helical surface states of TDSMs, such as $\mathrm{Cd_3 As_2}$ and
+$\mathrm{Na_3 Bi}$, which are robust against disorder. Based on a junction of
+two FMIs connected by a TDSM, we demonstrate that the magnetization dynamics in
+one FMI induces a spin current on the TDSM surface flowing to the other FMI. By
+both the analytical transport theory on the surface and the numerical
+simulation of real-time evolution in the bulk, we find that the induced spin
+current takes a universal semi-quantized value that is insensitive to the
+microscopic coupling structure between the FMI and the TDSM. We show that this
+surface spin current is robust against disorder over a long range, which
+indicates that the TDSM surface serves as a promising system for realizing
+spintronics devices.",2103.06519v1
+2021-04-09,Spin diffusion length associated to out-of-plane resistivity of Pt thin films in spin pumping experiments,"We present a broadband ferromagnetic resonance study of the Gilbert damping
+enhancement ($\Delta \alpha$) due to spin pumping in NiFe/Pt bilayers. The
+bilayers, which have negligible interfacial spin memory loss, are studied as a
+function of the Pt layer thickness ($t_{\text{Pt}}$) and temperature (100-293
+K). Within the framework of diffusive spin pumping theory, we demonstrate that
+Dyakonov-Perel (DP) or Elliot-Yaffet (EY) spin relaxation mechanisms acting
+alone are incompatible with our observations. In contrast, if we consider that
+the relation between spin relaxation characteristic time ($\tau_{\text{s}}$)
+and momentum relaxation characteristic time ($\tau_{\text{p}}$) is determined
+by a superposition of DP and EY mechanisms, the qualitative and quantitative
+agreement with experimental results is excellent. Remarkably, we found that
+$\tau_{\text{p}}$ must be determined by the out-of-plane electrical resistivity
+($\rho$) of the Pt film and hence its spin diffusion length
+($\lambda_{\text{Pt}}$) is independent of $t_{\text{Pt}}$. Our work settles the
+controversy regarding the $t_{\text{Pt}}$ dependence of $\lambda_{\text{Pt}}$
+by demonstrating its fundamental connection with $\rho$ considered along the
+same direction of spin current flow. \end{abstract}",2104.04426v1
+2021-05-05,Ni$_{80}$Fe$_{20}$ Nanotubes with Optimized Spintronic Functionalities Prepared by Atomic Layer Deposition,"Permalloy Ni$_{80}$Fe$_{20}$ is one of the key magnetic materials in the
+field of magnonics. Its potential would be further unveiled if it could be
+deposited in three dimensional (3D) architectures of sizes down to the
+nanometer. Atomic Layer Deposition, ALD, is the technique of choice for
+covering arbitrary shapes with homogeneous thin films. Early successes with
+ferromagnetic materials include nickel and cobalt. Still, challenges in
+depositing ferromagnetic alloys reside in the synthesis via decomposing the
+consituent elements at the same temperature and homogeneously. We report
+plasma-enhanced ALD to prepare permalloy Ni$_{80}$Fe$_{20}$ thin films and
+nanotubes using nickelocene and iron(III) tert-butoxide as metal precursors,
+water as the oxidant agent and an in-cycle plasma enhanced reduction step with
+hydrogen. We have optimized the ALD cycle in terms of Ni:Fe atomic ratio and
+functional properties. We obtained a Gilbert damping of 0.013, a resistivity of
+28 $\mu\Omega$cm and an anisotropic magnetoresistance effect of 5.6 $\%$ in the
+planar thin film geometry. We demonstrate that the process also works for
+covering GaAs nanowires, resulting in permalloy nanotubes with high aspect
+ratios and diameters of about 150 nm. Individual nanotubes were investigated in
+terms of crystal phase, composition and spin-dynamic response by microfocused
+Brillouin Light Scattering. Our results enable NiFe-based 3D spintronics and
+magnonic devices in curved and complex topology operated in the GHz frequency
+regime.",2105.01969v1
+2021-06-23,Spin dynamics of itinerant electrons: local magnetic moment formation and Berry phase,"The state-of-the-art theoretical description of magnetic materials relies on
+solving effective Heisenberg spin problems or their generalizations to
+relativistic or multi-spin-interaction cases that explicitly assume the
+presence of local magnetic moments in the system. We start with a general
+interacting fermionic model that is often obtained in ab initio electronic
+structure calculations and show that the corresponding spin problem can be
+introduced even in the paramagnetic regime, which is characterized by a zero
+average value of the magnetization. Further, we derive a physical criterion for
+the formation of the local magnetic moment and confirm that the latter exists
+already at high temperatures well above the transition to the ordered magnetic
+state. The use of path-integral techniques allows us to disentangle spin and
+electronic degrees of freedom and to carefully separate rotational dynamics of
+the local magnetic moment from Higgs fluctuations of its absolute value. It
+also allows us to accurately derive the topological Berry phase and relate it
+to a physical bosonic variable that describes dynamics of the spin degrees of
+freedom. As the result, we demonstrate that the equation of motion in the case
+of a large magnetic moment takes a conventional Landau-Lifshitz form that
+explicitly accounts for the Gilbert damping due to itinerant nature of the
+original electronic model.",2106.12462v3
+2021-11-20,Skyrmionics in correlated oxides,"While chiral magnets, metal-based magnetic multilayers, or Heusler compounds
+have been considered as the material workhorses in the field of skyrmionics,
+oxides are now emerging as promising alternatives, as they host special
+correlations between the spin-orbital-charge-lattice degrees of freedom and/or
+coupled ferroic order parameters. These interactions open new possibilities for
+practically exploiting skyrmionics. In this article, we review the recent
+advances in the observation and control of topological spin textures in various
+oxide systems. We start with the discovery of skyrmions and related
+quasiparticles in bulk and heterostructure ferromagnetic oxides. Next, we
+emphasize the shortcomings of implementing ferromagnetic textures, which have
+led to the recent explorations of ferrimagnetic and antiferromagnetic oxide
+counterparts, with higher Curie temperatures, stray-field immunity, low Gilbert
+damping, ultrafast magnetic dynamics, and/or absence of skyrmion deflection.
+Then, we highlight the development of novel pathways to control the stability,
+motion, and detection of topological textures using electric fields and
+currents. Finally, we present the outstanding challenges that need to be
+overcome to achieve all-electrical, nonvolatile, low-power oxide skyrmionic
+devices.",2111.10562v2
+2021-12-01,Unconditional well-posedness and IMEX improvement of a family of predictor-corrector methods in micromagnetics,"Recently, Kim & Wilkening (Convergence of a mass-lumped finite element method
+for the Landau-Lifshitz equation, Quart. Appl. Math., 76, 383-405, 2018)
+proposed two novel predictor-corrector methods for the Landau-Lifshitz-Gilbert
+equation (LLG) in micromagnetics, which models the dynamics of the
+magnetization in ferromagnetic materials. Both integrators are based on the
+so-called Landau-Lifshitz form of LLG, use mass-lumped variational formulations
+discretized by first-order finite elements, and only require the solution of
+linear systems, despite the nonlinearity of LLG. The first(-order in time)
+method combines a linear update with an explicit projection of an intermediate
+approximation onto the unit sphere in order to fulfill the LLG-inherent
+unit-length constraint at the discrete level. In the second(-order in time)
+integrator, the projection step is replaced by a linear constraint-preserving
+variational formulation. In this paper, we extend the analysis of the
+integrators by proving unconditional well-posedness and by establishing a close
+connection of the methods with other approaches available in the literature.
+Moreover, the new analysis also provides a well-posed integrator for the
+Schr\""odinger map equation (which is the limit case of LLG for vanishing
+damping). Finally, we design an implicit-explicit strategy for the treatment of
+the lower-order field contributions, which significantly reduces the
+computational cost of the schemes, while preserving their theoretical
+properties.",2112.00451v1
+2021-12-21,Fast long-wavelength exchange spin waves in partially-compensated Ga:YIG,"Spin waves in yttrium iron garnet (YIG) nano-structures attract increasing
+attention from the perspective of novel magnon-based data processing
+applications. For short wavelengths needed in small-scale devices, the group
+velocity is directly proportional to the spin-wave exchange stiffness constant
+$\lambda_\mathrm{ex}$. Using wave vector resolved Brillouin Light Scattering
+(BLS) spectroscopy, we directly measure $\lambda_\mathrm{ex}$ in Ga-substituted
+YIG thin films and show that it is about three times larger than for pure YIG.
+Consequently, the spin-wave group velocity overcomes the one in pure YIG for
+wavenumbers $k > 4$ rad/$\mu$m, and the ratio between the velocities reaches a
+constant value of around 3.4 for all $k > 20$ rad/$\mu$m. As revealed by
+vibrating-sample magnetometry (VSM) and ferromagnetic resonance (FMR)
+spectroscopy, Ga:YIG films with thicknesses down to 59 nm have a low Gilbert
+damping ($\alpha < 10^{-3}$), a decreased saturation magnetization $\mu_0
+M_\mathrm{S}~\approx~20~$mT and a pronounced out-of-plane uniaxial anisotropy
+of about $\mu_0 H_{\textrm{u1}} \approx 95 $ mT which leads to an out-of-plane
+easy axis. Thus, Ga:YIG opens access to fast and isotropic spin-wave transport
+for all wavelengths in nano-scale systems independently of dipolar effects.",2112.11348v1
+2022-01-27,Magnon transport and thermoelectric effects in ultrathin Tm3Fe5O12/Pt nonlocal devices,"The possibility of electrically exciting and detecting magnon currents in
+magnetic insulators has opened exciting perspectives for transporting spin
+information in electronic devices. However, the role of the magnetic field and
+the nonlocal thermal gradients on the magnon transport remain unclear. Here, by
+performing nonlocal harmonic voltage measurements, we investigate magnon
+transport in perpendicularly magnetized ultrathin Tm3Fe5O12 (TmIG) films
+coupled to Pt electrodes. We show that the first harmonic nonlocal voltage
+captures spin-driven magnon transport in TmIG, as expected, and the second
+harmonic is dominated by thermoelectric voltages driven by current-induced
+thermal gradients at the detector. The magnon diffusion length in TmIG is found
+to be on the order of 0.3 {\mu}m at 0.5 T and gradually decays to 0.2 {\mu}m at
+0.8 T, which we attribute to the suppression of the magnon relaxation time due
+to the increase of the Gilbert damping with field. By performing current,
+magnetic field, and distance dependent nonlocal and local measurements we
+demonstrate that the second harmonic nonlocal voltage exhibits five
+thermoelectric contributions, which originate from the nonlocal spin Seebeck
+effect and the ordinary, planar, spin, and anomalous Nernst effects. Our work
+provides a guide on how to disentangle magnon signals from diverse
+thermoelectric voltages of spin and magnetic origin in nonlocal magnon devices,
+and establish the scaling laws of the thermoelectric voltages in
+metal/insulator bilayers.",2201.11353v1
+2022-01-31,Tuning spin-orbit torques across the phase transition in VO$_2$/NiFe heterostructure,"The emergence of spin-orbit torques as a promising approach to
+energy-efficient magnetic switching has generated large interest in material
+systems with easily and fully tunable spin-orbit torques. Here, current-induced
+spin-orbit torques in VO$_2$/NiFe heterostructures were investigated using
+spin-torque ferromagnetic resonance, where the VO$_2$ layer undergoes a
+prominent insulator-metal transition. A roughly two-fold increase in the
+Gilbert damping parameter, $\alpha$, with temperature was attributed to the
+change in the VO$_2$/NiFe interface spin absorption across the VO$_2$ phase
+transition. More remarkably, a large modulation ($\pm$100%) and a sign change
+of the current-induced spin-orbit torque across the VO$_2$ phase transition
+suggest two competing spin-orbit torque generating mechanisms. The bulk spin
+Hall effect in metallic VO$_2$, corroborated by our first-principles
+calculation of spin Hall conductivity, $\sigma_{SH} \approx 10^4
+\frac{\hbar}{e} \Omega^{-1} m^{-1}$, is verified as the main source of the
+spin-orbit torque in the metallic phase. The self-induced/anomalous torque in
+NiFe, of the opposite sign and a similar magnitude to the bulk spin Hall effect
+in metallic VO$_2$, could be the other competing mechanism that dominates as
+temperature decreases. For applications, the strong tunability of the torque
+strength and direction opens a new route to tailor spin-orbit torques of
+materials which undergo phase transitions for new device functionalities.",2201.12984v1
+2022-02-03,Controlling spin pumping into superconducting Nb by proximity-induced spin-triplet Cooper pairs,"Proximity-induced long-range spin-triplet supercurrents, important for the
+field of superconducting spintronics, are generated in
+superconducting/ferromagnetic heterostructures when interfacial magnetic
+inhomogeneities responsible for spin mixing and spin flip scattering are
+present. The multilayer stack Nb/Cr/Fe/Cr/Nb has been shown to support such
+exotic currents when fabricated into Josephson junction devices. However,
+creating pure spin currents controllably in superconductors outside of the
+Josephson junction architecture is a bottleneck to progress. Recently,
+ferromagnetic resonance was proposed as a possible direction, the signature of
+pure supercurrent creation being an enhancement of the Gilbert damping below
+the superconducting critical temperature, but the necessary conditions are
+still poorly established. Consistent with theoretical prediction, we
+demonstrate conclusively that pumping pure spin currents into a superconductor
+is only possible when conditions supporting proximity-induced spin-triplet
+effects are satisfied. Our study is an important step forward for
+superconducting pure spin current creation and manipulation, considerably
+advancing the field of superconducting spintronics.",2202.01520v1
+2022-06-17,Multiscale Modelling of the Antiferromagnet Mn2Au: From ab-initio to Micromagnetics,"Antiferromagnets (AFMs) are strong candidates for the future spintronic and
+memory applications largely because of their inherently fast dynamics and lack
+of stray fields, with Mn2Au being one of the most promising. For the numerical
+modelling of magnetic material properties, it is common to use ab-initio
+methods, atomistic models and micromagnetics. However, each method alone
+describes the physics within certain limits. Multiscale methods bridging the
+gap between these three approaches have been already proposed for ferromagnetic
+materials. Here, we present a complete multiscale model of the AFM Mn2Au as an
+exemplar material, starting with results from ab-initio methods going via
+atomistic spin dynamics (ASD) to an AFM Landau-Lifshitz-Bloch (AFM-LLB) model.
+Firstly, bulk is modelled using a classical spin Hamiltonian constructed based
+on earlier first-principles calculations. Secondly, this spin model is used in
+the stochastic Landau-Lifshitz-Gilbert (LLG) to calculate temperature-dependent
+equilibrium properties, such as magnetization and magnetic susceptibilities.
+Thirdly, the temperature dependent micromagnetic parameters are used in the
+AFM-LLB. We validate our approach by comparing the ASD and AFM-LLB models for
+three paradigmatic cases; (i) Damped magnetic oscillations, (ii) magnetization
+dynamics following a heat pulse resembling pump-probe experiments, (iii)
+magnetic domain wall motion under thermal gradients.",2206.08625v1
+2022-10-29,Micromagnetic frequency-domain simulation methods for magnonic systems,"We present efficient numerical methods for the simulation of small
+magnetization oscillations in three-dimensional micromagnetic systems.
+Magnetization dynamics is described by the Landau-Lifshitz-Gilbert (LLG)
+equation, linearized in the frequency domain around a generic equilibrium
+configuration, and formulated in a special operator form that allows leveraging
+large-scale techniques commonly used to evaluate the effective field in
+time-domain micromagnetic simulations. By using this formulation, we derive
+numerical algorithms to compute the free magnetization oscillations (i.e., spin
+wave eigenmodes) as well as magnetization oscillations driven by ac
+radio-frequency fields for arbitrarily shaped nanomagnets. Moreover,
+semi-analytical perturbation techniques based on the computation of a reduced
+set of eigenmodes are provided for fast evaluation of magnetization frequency
+response and absorption spectra as a function of damping and ac field. We
+present both finite difference and finite element implementations and
+demonstrate their effectiveness on a test case. These techniques open the
+possibility to study generic magnonic systems discretized with several hundred
+thousand (or even millions) of computational cells in a reasonably short time.",2210.16564v3
+2023-03-07,Magnon currents excited by the spin Seebeck effect in ferromagnetic EuS thin films,"A magnetic insulator is an ideal platform to propagate spin information by
+exploiting magnon currents. However, until now, most studies have focused on
+Y$_3$Fe$_5$O$_{12}$ (YIG) and a few other ferri- and antiferromagnetic
+insulators, but not on pure ferromagnets. In this study, we demonstrate for the
+first time that magnon currents can propagate in ferromagnetic insulating thin
+films of EuS. By performing both local and non-local transport measurements in
+18-nm-thick films of EuS using Pt electrodes, we detect magnon currents arising
+from thermal generation by the spin Seebeck effect. By comparing the dependence
+of the local and non-local signals with the temperature (< 30 K) and magnetic
+field (< 9 T), we confirm the magnon transport origin of the non-local signal.
+Finally, we extract the magnon diffusion length in the EuS film (~140 nm), a
+short value in good correspondence with the large Gilbert damping measured in
+the same film.",2303.03833v2
+2023-04-01,A coupled magneto-structural continuum model for multiferroic $\mathrm{BiFeO}_3$,"A continuum approach to study magnetoelectric multiferroic $\mathrm{BiFeO}_3$
+(BFO) is proposed. Our modeling effort marries the ferroelectric (FE) phase
+field method and micromagnetic simulations in order to describe the entire
+multiferroic order parameter sector (polarization, oxygen antiphase tilts,
+strain, and magnetism) self-consistently on the same time and length scale. In
+this paper, we discuss our choice of ferroelectric and magnetic energy terms
+and demonstrate benchmarks against known behavior. We parameterize the lowest
+order couplings of the structural distortions against previous predictions from
+density functional theory calculations giving access to simulations of the FE
+domain wall (DW) topology. This allows us to estimate the energetic hierarchy
+and thicknesses of the numerous structural DWs. We then extend the model to the
+canted antiferromagnetic order and demonstrate how the ferroelectric domain
+boundaries influence the resulting magnetic DWs. We also highlight some
+capabilities of this model by providing two examples relevant for applications.
+We demonstrate spin wave transmission through the multiferroic domain
+boundaries which identify rectification in qualitative agreement with recent
+experimental observations. As a second example of application, we model
+fully-dynamical magnetoelectric switching, where we find a sensitivity on the
+Gilbert damping with respect to switching pathways. We envision that this
+modeling effort will set the basis for further work on properties of arbitrary
+3D nanostructures of BFO (and related multiferroics) at the mesoscale.",2304.00270v1
+2023-09-18,Coherent Tunneling and Strain Sensitivity of an All Heusler Alloy Magnetic Tunneling Junction: A First-Principles Study,"Half-metallic Co-based full Heusler alloys have captured considerable
+attention of the researchers in the realm of spintronic applications, owing to
+their remarkable characteristics such as exceptionally high spin polarization
+at Fermi level, ultra-low Gilbert damping, and high Curie temperature. In this
+comprehensive study, employing density functional theory, we delve into the
+stability and electron transport properties of a magnetic tunneling junction
+(MTJ) comprising a Co$_2$MnSb/HfIrSb interface. Utilizing a standard model
+given by Julliere, we estimate the tunnel magnetoresistance (TMR) ratio of this
+heterojunction under external electric field, revealing a significantly high
+TMR ratio (500%) that remains almost unaltered for electric field magnitudes up
+to 0.5 V/A. In-depth investigation of K-dependent majority spin transmissions
+uncovers the occurrence of coherent tunneling for the Mn-Mn/Ir interface,
+particularly when a spacer layer beyond a certain thickness is employed.
+Additionally, we explore the impact of bi-axial strain on the MTJ by varying
+the in-plane lattice constants between -4% and +4%. Our spin-dependent
+transmission calculations demonstrate that the Mn-Mn/Ir interface manifests
+strain-sensitive transmission properties under both compressive and tensile
+strain, and yields a remarkable three-fold increase in majority spin
+transmission under tensile strain conditions. These compelling outcomes place
+the Co2MnSb/HfIrSb junction among the highly promising candidates for nanoscale
+spintronic devices, emphasizing the potential significance of the system in the
+advancement of the field.",2309.09755v1
+2023-10-27,Effect of interfacial Dzyaloshinskii-Moriya interaction in spin dynamics of an Antiferromagnet coupled Ferromagnetic double-barrier Magnetic Tunnel Junction,"In this work, we have studied the spin dynamics of a synthethic
+Antiferromagnet (SAFM)$|$Heavy Metal (HM)$|$Ferromagnet (FM) double barrier
+magnetic tunnel junction (MTJ) in presence of Ruderman-Kittel-Kasuya-Yoside
+interaction (RKKYI), interfacial Dzyaloshinskii-Moriya interaction (iDMI),
+N\'eel field and Spin-Orbit Coupling (SOC) with different Spin Transfer Torque
+(STT). We employ Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation to
+investigate the AFM dynamics of the proposed system. We found that the system
+exhibits a transition from regular to damped oscillations with the increase in
+strength of STT for systems with weaker iDMI than RKKYI while display sustained
+oscillatons for system having same order of iDMI and RKKYI. On the other hand
+the iDMI dominating system exhibits self-similar but aperiodic patterns in
+absence of N\'eel field. In the presence of N\'eel field, the RKKYI dominating
+systems exhibit chaotic oscillations for low STT but display sustained
+oscillation under moderate STT. Our results suggest that the decay time of
+oscillations can be controlled via SOC. The system can works as an oscillator
+for low SOC but display nonlinear characteristics with the rise in SOC for
+systems having weaker iDMI than RKKYI while an opposite characteristic are
+noticed for iDMI dominating systems. We found periodic oscillations under low
+external magnetic field in RKKYI dominating systems while moderate field are
+necessary for sustained oscillation in iDMI dominating systems. Moreover, the
+system exhibits saddle-node bifurcation and chaos under moderate N\'eel field
+and SOC with suitable iDMI and RKKYI. In addition, our results indicate that
+the magnon lifetime can be enhanced by increasing the strength of iDMI for both
+optical and acoustic modes.",2310.18175v1
+2023-11-14,Berry curvature induced giant intrinsic spin-orbit torque in single layer magnetic Weyl semimetal thin films,"Topological quantum materials can exhibit unconventional surface states and
+anomalous transport properties, but their applications to spintronic devices
+are restricted as they require the growth of high-quality thin films with
+bulk-like properties. Here, we study 10--30 nm thick epitaxial ferromagnetic
+Co$_{\rm 2}$MnGa films with high structural order. Very high values of the
+anomalous Hall conductivity, $\sigma_{\rm xy}=1.35\times10^{5}$ $\Omega^{-1}
+m^{-1}$, and the anomalous Hall angle, $\theta_{\rm H}=15.8\%$, both comparable
+to bulk values. We observe a dramatic crystalline orientation dependence of the
+Gilbert damping constant of a factor of two and a giant intrinsic spin Hall
+conductivity, $\mathit{\sigma_{\rm SHC}}=(6.08\pm 0.02)\times 10^{5}$
+($\hbar/2e$) $\Omega^{-1} m^{-1}$, which is an order of magnitude higher than
+literature values of single-layer Ni$_{\rm 80}$Fe$_{\rm 20}$, Ni, Co, Fe, and
+multilayer Co$_{\rm 2}$MnGa stacks. Theoretical calculations of the intrinsic
+spin Hall conductivity, originating from a strong Berry curvature, corroborate
+the results and yield values comparable to the experiment. Our results open up
+for the design of spintronic devices based on single layers of topological
+quantum materials.",2311.08145v2
+2023-12-26,All solution grown epitaxial magnonic crystal of thulium iron garnet thin film,"Magnonics has shown the immense potential of compatibility with CMOS devices
+and the ability to be utilized in futuristic quantum computing. Therefore, the
+magnonic crystals, both metallic and insulating, are under extensive
+exploration. The presence of high spin-orbit interaction induced by the
+presence of rare-earth elements in thulium iron garnet (TmIG) increases its
+potential in magnonic applications. Previously, TmIG thin films were grown
+using ultra-high vacuum-based techniques. Here, we present a cost-effective
+solution-based approach that enables the excellent quality interface and
+surface roughness of the epitaxial TmIG/GGG. The deposited TmIG (12.2 nm) thin
+film's physical and spin dynamic properties are investigated in detail. The
+confirmation of the epitaxy using X-ray diffraction in $\phi$-scan geometry
+along with the X-ray reflectivity and atomic force for the thickness and
+roughness analysis and topography, respectively. The epitaxial TmIG/GGG have
+confirmed the perpendicular magnetic anisotropy utilizing the
+polar-magneto-optic Kerr effect. Analyzing the ferromagnetic resonance study of
+TmIG/GGG thin films provides the anisotropy constant K$_U$ = 20.6$\times$10$^3$
+$\pm$ 0.2$\times$10$^3$ N/m$^2$ and the Gilbert damping parameter $\alpha$ =
+0.0216 $\pm$ 0.0028. The experimental findings suggest that the
+solution-processed TmIG/GGG thin films have the potential to be utilized in
+device applications.",2312.15973v1
+2024-03-01,Spin current control of magnetism,"Exploring novel strategies to manipulate the order parameter of magnetic
+materials by electrical means is of great importance, not only for advancing
+our understanding of fundamental magnetism, but also for unlocking potential
+practical applications. A well-established concept to date uses gate voltages
+to control magnetic properties, such as saturation magnetization, magnetic
+anisotropies, coercive field, Curie temperature and Gilbert damping, by
+modulating the charge carrier population within a capacitor structure. Note
+that the induced carriers are non-spin-polarized, so the control via the
+electric-field is independent of the direction of the magnetization. Here, we
+show that the magnetocrystalline anisotropy (MCA) of ultrathin Fe films can be
+reversibly modified by a spin current generated in Pt by the spin Hall effect.
+The effect decreases with increasing Fe thickness, indicating that the origin
+of the modification can be traced back to the interface. Uniquely, the change
+in MCA due to the spin current depends not only on the polarity of the charge
+current but also on the direction of magnetization, i.e. the change in MCA has
+opposite sign when the direction of magnetization is reversed. The control of
+magnetism by the spin current results from the modified exchange splitting of
+majority- and minority-spin bands, and differs significantly from the
+manipulation by gate voltages via a capacitor structure, providing a
+functionality that was previously unavailable and could be useful in advanced
+spintronic devices.",2403.00709v1
+2004-04-06,Bounds for contractive semigroups and second order systems,"We derive a uniform bound for the difference of two contractive semigroups,
+if the difference of their generators is form-bounded by the Hermitian parts of
+the generators themselves. We construct a semigroup dynamics for second order
+systems with fairly general operator coefficients and apply our bound to the
+perturbation of the damping term. The result is illustrated on a dissipative
+wave equation. As a consequence the exponential decay of some second order
+systems is proved.",0404120v1
+1998-05-29,Magnetic Faraday-Instability,"In a magnetic fluid parametrically driven surface waves can be excited by an
+external oscillating magnetic field. A static magnetic field changes the
+restoring forces and damping coefficients of the various surface waves. This
+property enables the excitation of both subharmonic and harmonic responses of
+the standing waves.",9806001v1
+2003-12-10,Charge Fluctuation of Dust Grains and its Impact on Dusty Wave Propagation,"In this paper we consider the influence of dust charge fluctuations on
+damping of the dust-ion-acoustic waves. Fluid approximation of longitudinal
+electrostatic waves in unmagnetized plasmas is considered. We show that for a
+weak acoustic wave the attenuation depends on a phenomenological charging
+coefficient.",0312067v1
+2005-07-26,On simulations of the classical harmonic oscillator equation by difference equations,"We show that any second order linear ordinary diffrential equation with
+constant coefficients (including the damped and undumped harmonic oscillator
+equation) admits an exact discretization, i.e., there exists a difference
+equation whose solutions exactly coincide with solutions of the corresponding
+differential equation evaluated at a discrete sequence of points (a lattice).
+Such exact discretization is found for an arbitrary lattice spacing.",0507182v1
+1998-02-16,Classical states via decoherence,"The initial states which minimize the predictability loss for a damped
+harmonic oscillator are identified as quasi-free states with a symmetry
+dictated by the environment's diffusion coefficients. For an isotropic
+diffusion in phase space, coherent states (or mixtures of coherent states) are
+selected as the most stable ones.",9802044v1
+2007-11-15,$C^m$-theory of damped wave equations with stabilisation,"The aim of this note is to extend the energy decay estimates from [J. Wirth,
+J. Differential Equations 222 (2006) 487--514] to a broader class of
+time-dependent dissipation including very fast oscillations. This is achieved
+using stabilisation conditions on the coefficient in the spirit of [F.
+Hirosawa, Math. Ann. 339/4 (2007) 819--839].",0711.2403v1
+2014-04-22,A unique continuation result for the plate equation and an application,"In this paper, we prove the unique continuation property for the weak
+solution of the plate equation with non-smooth coefficients. Then, we apply
+this result to study the global attractor for the semilinear plate equation
+with a localized damping.",1404.5586v3
+2017-09-24,Exceptional points in two simple textbook examples,"We propose to introduce the concept of exceptional points in intermediate
+courses on mathematics and classical mechanics by means of simple textbook
+examples. The first one is an ordinary second-order differential equation with
+constant coefficients. The second one is the well known damped harmonic
+oscillator. They enable one to connect the occurrence of linearly dependent
+exponential solutions with a defective matrix that cannot be diagonalized but
+can be transformed into a Jordan canonical form.",1710.00067v1
+2019-06-06,Well-posedness and exponential decay estimates for a Korteweg-de Vries-Burgers equation with time-delay,"We consider the KdV-Burgers equation and its linear version in presence of a
+delay feedback. We prove well-posedness of the models and exponential decay
+estimates under appropriate conditions on the damping coefficients. Our
+arguments rely on a Lyapunov functional approach combined with a step by step
+procedure and semigroup theory.",1906.02488v1
+2021-07-21,"Convergence rates for the Heavy-Ball continuous dynamics for non-convex optimization, under Polyak-Łojasiewicz condition","We study convergence of the trajectories of the Heavy Ball dynamical system,
+with constant damping coefficient, in the framework of convex and non-convex
+smooth optimization. By using the Polyak-{\L}ojasiewicz condition, we derive
+new linear convergence rates for the associated trajectory, in terms of
+objective function values, without assuming uniqueness of the minimizer.",2107.10123v2
+2021-08-29,Well-posedness and stability for semilinear wave-type equations with time delay,"In this paper we analyze a semilinear abstract damped wave-type equation with
+time delay. We assume that the delay feedback coefficient is variable in time
+and belonging to $L^1_{loc}([0, +\infty)).$ Under suitable assumptions, we show
+well-posedness and exponential stability for small initial data. Our strategy
+combines careful energy estimates and continuity arguments. Some examples
+illustrate the abstract results.",2108.12786v1
+2021-10-22,p-Laplacian wave equations in non-cylindrical domains,"This paper is devoted to studying the stability of p-Laplacian wave equations
+with strong damping in non-cylindrical domains. The method of proof based on
+some estimates for time-varying coefficients rising from moving boundary and a
+modified Kormonik inequality. Meanwhile, by selecting appropriate auxiliary
+functions, finally we obtain the polynomial stability (p > 2) and exponential
+stability (p = 2) for such systems in some unbounded development domains.",2110.11547v1
+2022-07-25,Inviscid limit for the compressible Navier-Stokes equations with density dependent viscosity,"We consider the compressible Navier-Stokes system describing the motion of a
+barotropic fluid with density dependent viscosity confined in a
+three-dimensional bounded domain $\Omega$. We show the convergence of the weak
+solution to the compressible Navier-Stokes system to the strong solution to the
+compressible Euler system when the viscosity and the damping coefficients tend
+to zero.",2207.12222v1
+2018-05-08,Effect of transport coefficients on excitation of flare-induced standing slow-mode waves in coronal loops,"Standing slow-mode waves have been recently observed in flaring loops by the
+Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO). By
+means of the coronal seismology technique transport coefficients in hot
+($\sim$10 MK) plasma were determined by Wang et al.(2015, Paper I), revealing
+that thermal conductivity is nearly suppressed and compressive viscosity is
+enhanced by more than an order of magnitude. In this study we use 1D nonlinear
+MHD simulations to validate the predicted results from the linear theory and
+investigate the standing slow-mode wave excitation mechanism. We first explore
+the wave trigger based on the magnetic field extrapolation and flare emission
+features. Using a flow pulse driven at one footpoint we simulate the wave
+excitation in two types of loop models: model 1 with the classical transport
+coefficients and model 2 with the seismology-determined transport coefficients.
+We find that model 2 can form the standing wave pattern (within about one
+period) from initial propagating disturbances much faster than model 1, in
+better agreement with the observations. Simulations of the harmonic waves and
+the Fourier decomposition analysis show that the scaling law between damping
+time ($\tau$) and wave period ($P$) follows $\tau\propto{P^2}$ in model 2,
+while $\tau\propto{P}$ in model 1. This indicates that the largely enhanced
+viscosity efficiently increases the dissipation of higher harmonic components,
+favoring the quick formation of the fundamental standing mode. Our study
+suggests that observational constraints on the transport coefficients are
+important in understanding both, the wave excitation and damping mechanisms.",1805.03282v1
+2005-01-02,Effect of dipolar interactions on the magnetization of a cubic array of nanomagnets,"We investigated the effect of intermolecular dipolar interactions on a cubic
+3D ensemble of 5X5X4=100 nanomagnets, each with spin $S = 5$. We employed the
+Landau-Lifshitz-Gilbert equation to solve for the magnetization $M(B)$ curves
+for several values of the damping constant $\alpha$, the induction sweep rate,
+the lattice constant $a$, the temperature $T$, and the magnetic anisotropy
+field $H_A$. We find that the smaller the $\alpha$, the stronger the maximum
+induction required to produce hysteresis. The shape of the hysteresis loops
+also depends on the damping constant. We find further that the system
+magnetizes and demagnetizes at decreasing magnetic field strengths with
+decreasing sweep rates, resulting in smaller hysteresis loops. Variations of
+$a$ within realistic values (1.5 nm - 2.5 nm) show that the dipolar interaction
+plays an important role in the magnetic hysteresis by controlling the
+relaxation process. The $T$ dependencies of $\alpha$ and of $M$ are presented
+and discussed with regard to recent experimental data on nanomagnets. $H_A$
+enhances the size of the hysteresis loops for external fields parallel to the
+anisotropy axis, but decreases it for perpendicular external fields. Finally,
+we reproduce and test an $M(B)$ curve for a 2D-system [M. Kayali and W. Saslow,
+Phys. Rev. B {\bf 70}, 174404 (2004)]. We show that its hysteretic behavior is
+only weakly dependent on the shape anisotropy field and the sweep rate, but
+depends sensitively upon the dipolar interactions. Although in 3D systems,
+dipole-dipole interactions generally diminish the hysteresis, in 2D systems,
+they strongly enhance it. For both square 2D and rectangular 3D lattices with
+${\bm B}||(\hat{\bm x}+\hat{\bm y})$, dipole-dipole interactions can cause
+large jumps in the magnetization.",0501006v2
+2019-03-07,"Uniaxial anisotropy, intrinsic and extrinsic damping in Co$_{2}$FeSi Heusler alloy thin films","Ferromagnetic resonance (FMR) technique has been used to study the
+magnetization relaxation processes and magnetic anisotropy in two different
+series of the Co2FeSi (CFS) Heusler alloy thin films, deposited on the Si(111)
+substrate by UHV sputtering. While the CFS films of fixed (50 nm) thickness,
+deposited at different substrate temperatures (TS) ranging from room
+temperature (RT) to 600^C, constitute the series-I, the CFS films with
+thickness t varying from 12 nm to 100 nm and deposited at 550^C make up the
+series-II. In series-I, the CFS films deposited at TS = RT and 200^C are
+completely amorphous, the one at TS = 300^C is partially crystalline, and those
+at TS equal 450^C, 550^C and 600^C are completely crystalline with B2 order. By
+contrast, all the CFS films in series-II are in the fully-developed B2
+crystalline state. Irrespective of the strength of disorder and film thickness,
+angular variation of the resonance field in the film plane unambiguously
+establishes the presence of global in-plane uniaxial anisotropy. Angular
+variation of the linewidth in the film plane reveals that, in the CFS thin
+films of varying thickness, a crossover from the in-plane local four-fold
+symmetry (cubic anisotropy) to local two-fold symmetry (uniaxial anisotropy)
+occurs as t exceeds 50 nm. Gilbert damping parameter {\alpha} decreases
+monotonously from 0.047 to 0.0078 with decreasing disorder strength (increasing
+TS) and jumps from 0.008 for the CFS film with t = 50 nm to 0.024 for the film
+with t equal 75 nm. Such variations of {\alpha} with TS and t are understood in
+terms of the changes in the total (spin-up and spin-down) density of states at
+the Fermi level caused by the disorder and film thickness.",1903.02976v1
+2023-09-19,Impact of strain on the SOT-driven dynamics of thin film Mn$_3$Sn,"Mn$_3$Sn, a metallic antiferromagnet with an anti-chiral 120$^\circ$ spin
+structure, generates intriguing magneto-transport signatures such as a large
+anomalous Hall effect, spin-polarized current with novel symmetries, anomalous
+Nernst effect, and magneto-optic Kerr effect. When grown epitaxially as
+MgO(110)[001]$\parallel$ Mn$_3$Sn($0\bar{1}\bar{1}0$)[0001], Mn$_3$Sn
+experiences a uniaxial tensile strain, which changes the bulk six-fold
+anisotropy landscape to a perpendicular magnetic anisotropy with two stable
+states. In this work, we investigate the field-assisted spin orbit-torque
+(SOT)-driven response of the order parameter in single-domain Mn$_3$Sn with
+uniaxial tensile strain. We find that for a non-zero external magnetic field,
+the order parameter can be switched between the two stable states if the
+magnitude of the input current is between two field-dependent critical
+currents. Below the lower critical current, the order parameter exhibits a
+stationary state in the vicinity of the initial stable state. On the other
+hand, above the higher critical current, the order parameter shows oscillatory
+dynamics which could be tuned from the 100's of megahertz to the gigahertz
+range. We obtain approximate expressions of the two critical currents and find
+them to agree very well with the numerical simulations for experimentally
+relevant magnetic fields. We also obtain unified functional form of the
+switching time versus the input current for different magnetic fields. Finally,
+we show that for lower values of Gilbert damping ($\alpha \leq 2\times
+10^{-3}$), the critical currents and the final steady states depend
+significantly on the damping constant. The numerical and analytic results
+presented in our work can be used by both theorists and experimentalists to
+understand the SOT-driven order dynamics in PMA Mn$_3$Sn and design future
+experiments and devices.",2309.10246v2
+2009-04-16,Good Concatenated Code Ensembles for the Binary Erasure Channel,"In this work, we give good concatenated code ensembles for the binary erasure
+channel (BEC). In particular, we consider repeat multiple-accumulate (RMA) code
+ensembles formed by the serial concatenation of a repetition code with multiple
+accumulators, and the hybrid concatenated code (HCC) ensembles recently
+introduced by Koller et al. (5th Int. Symp. on Turbo Codes & Rel. Topics,
+Lausanne, Switzerland) consisting of an outer multiple parallel concatenated
+code serially concatenated with an inner accumulator. We introduce stopping
+sets for iterative constituent code oriented decoding using maximum a
+posteriori erasure correction in the constituent codes. We then analyze the
+asymptotic stopping set distribution for RMA and HCC ensembles and show that
+their stopping distance hmin, defined as the size of the smallest nonempty
+stopping set, asymptotically grows linearly with the block length. Thus, these
+code ensembles are good for the BEC. It is shown that for RMA code ensembles,
+contrary to the asymptotic minimum distance dmin, whose growth rate coefficient
+increases with the number of accumulate codes, the hmin growth rate coefficient
+diminishes with the number of accumulators. We also consider random puncturing
+of RMA code ensembles and show that for sufficiently high code rates, the
+asymptotic hmin does not grow linearly with the block length, contrary to the
+asymptotic dmin, whose growth rate coefficient approaches the Gilbert-Varshamov
+bound as the rate increases. Finally, we give iterative decoding thresholds for
+the different code ensembles to compare the convergence properties.",0904.2482v1
+2004-08-10,Cosmic Ray Scattering and Streaming in Compressible Magnetohydrodynamic Turbulence,"Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call
+for revisions in the picture of cosmic ray transport. In this paper we use
+recently obtained scaling laws for MHD modes to obtain the scattering frequency
+for cosmic rays. Using quasilinear theory we calculate gyroresonance with MHD
+modes (Alfv\'{e}nic, slow and fast) and transit-time damping (TTD) by fast
+modes. We provide calculations of cosmic ray scattering for various phases of
+interstellar medium with realistic interstellar turbulence driving that is
+consistent with the velocity dispersions observed in diffuse gas. We account
+for the turbulence cutoff arising from both collisional and collisionless
+damping. We obtain analytical expressions for diffusion coefficients that enter
+Fokker-Planck equation describing cosmic ray evolution. We obtain the
+scattering rate and show that fast modes provide the dominant contribution to
+cosmic ray scattering for the typical interstellar conditions in spite of the
+fact that fast modes are subjected to damping. We determine how the efficiency
+of the scattering depends on the characteristics of ionized media, e.g. plasma
+$\beta$. We calculate the range of energies for which the streaming instability
+is suppressed by the ambient MHD turbulence.",0408172v1
+1999-11-22,Two-fluid hydrodynamics of a Bose gas including damping from normal fluid transport coefficients,"We extend our recent work on the two-fluid hydrodynamics of the condensate
+and non-condensate in a trapped Bose gas by including the dissipation
+associated with viscosity and thermal conduction. For purposes of illustration,
+we consider the hydrodynamic modes in the case of a uniform Bose gas. A finite
+thermal conductivity and shear viscosity give rise to a damping of the first
+and second sound modes in addition to that found previously due to the lack of
+diffusive equilibrium between the condensate and non-condensate. The
+relaxational mode associated with this equilibration process is strongly
+coupled to thermal fluctuations and reduces to the usual thermal diffusion mode
+above the Bose-Einstein transition. In contrast to the standard Landau
+two-fluid hydrodynamics, we predict a damped mode centered at zero frequency,
+in addition to the usual second sound doublet.",9911336v1
+2001-11-14,"Soliton-radiation coupling in the parametrically driven, damped nonlinear Schrödinger equation","We use the Riemann-Hilbert problem to study the interaction of the soliton
+with radiation in the parametrically driven, damped nonlinear Schr\""odinger
+equation. The analysis is reduced to the study of a finite-dimensional
+dynamical system for the amplitude and phase of the soliton and the complex
+amplitude of the long-wavelength radiation. In contrast to previously utilised
+Inverse Scattering-based perturbation techniques, our approach is valid for
+arbitrarily large driving strengths and damping coefficients. We show that,
+contrary to suggestions made in literature, the complexity observed in the
+soliton's dynamics cannot be accounted for just by its coupling to the
+long-wavelength radiation.",0111034v1
+1996-12-08,Towards a Simple Model of Compressible Alfvenic Turbulence,"A simple model collisionless, dissipative, compressible MHD (Alfvenic)
+turbulence in a magnetized system is investigated. In contrast to more familiar
+paradigms of turbulence, dissipation arises from Landau damping, enters via
+nonlinearity, and is distributed over all scales. The theory predicts that two
+different regimes or phases of turbulence are possible, depending on the ratio
+of steepening to damping coefficient (m_1/m_2). For strong damping
+(|m_1/m_2|<1), a regime of smooth, hydrodynamic turbulence is predicted. For
+|m_1/m_2|>1, steady state turbulence does not exist in the hydrodynamic limit.
+Rather, spikey, small scale structure is predicted.",9612005v2
+2009-01-15,The sound damping constant for generalized theories of gravity,"The near-horizon metric for a black brane in Anti-de Sitter (AdS) space and
+the metric near the AdS boundary both exhibit hydrodynamic behavior. We
+demonstrate the equivalence of this pair of hydrodynamic systems for the sound
+mode of a conformal theory. This is first established for Einstein's gravity,
+but we then show how the sound damping constant will be modified, from its
+Einstein form, for a generalized theory. The modified damping constant is
+expressible as the ratio of a pair of gravitational couplings that are
+indicative of the sound-channel class of gravitons. This ratio of couplings
+differs from both that of the shear diffusion coefficient and the shear
+viscosity to entropy ratio. Our analysis is mostly limited to conformal
+theories but suggestions are made as to how this restriction might eventually
+be lifted.",0901.2191v1
+2009-07-30,Gas damping force noise on a macroscopic test body in an infinite gas reservoir,"We present a simple analysis of the force noise associated with the
+mechanical damping of the motion of a test body surrounded by a large volume of
+rarefied gas. The calculation is performed considering the momentum imparted by
+inelastic collisions against the sides of a cubic test mass, and for other
+geometries for which the force noise could be an experimental limitation. In
+addition to arriving at an accurated estimate, by two alternative methods, we
+discuss the limits of the applicability of this analysis to realistic
+experimental configurations in which a test body is surrounded by residual gas
+inside an enclosure that is only slightly larger than the test body itself.",0907.5375v2
+2011-03-08,Steady states of the parametric rotator and pendulum,"We discuss several steady-state rotation and oscillation modes of the planar
+parametric rotator and pendulum with damping. We consider a general elliptic
+trajectory of the suspension point for both rotator and pendulum, for the
+latter at an arbitrary angle with gravity, with linear and circular
+trajectories as particular cases. We treat the damped, non-linear equation of
+motion of the parametric rotator and pendulum perturbatively for small
+parametric excitation and damping, although our perturbative approach can be
+extended to other regimes as well. Our treatment involves only ordinary
+second-order differential equations with constant coefficients, and provides
+numerically accurate perturbative solutions in terms of elementary functions.
+Some of the steady-state rotation and oscillation modes studied here have not
+been discussed in the previous literature. Other well-known ones, such as
+parametric resonance and the inverted pendulum, are extended to elliptic
+parametric excitation tilted with respect to gravity. The results presented
+here should be accessible to advanced undergraduates, and of interest to
+graduate students and specialists in the field of non-linear mechanics.",1103.1413v1
+2011-03-28,Motion of position-dependent mass as a damping-antidamping process: Application to the Fermi gas and to the Morse potential,"The object of this paper is to investigate, classically and quantum
+mechanically, the relation existing between the position-dependent effective
+mass and damping-antidamping dynamics. The quantization of the equations of
+motion is carried out using the geometric interpretation of the motion, and we
+compare it with the one based on the ordering ambiguity scheme. Furthermore, we
+apply the obtained results to a Fermi gas of damped-antidamped particles, and
+we solve the Schr\""odinger equation for an exponentially increasing
+(decreasing) mass in the presence of the Morse potential.",1103.5440v3
+2011-06-22,Tunable Magnonic Frequency and Damping in [Co/Pd]8 Multilayers with Variable Co Layer Thickness,"We report the experimental observation of collective picosecond magnetization
+dynamics in [Co/Pd]8 multilayers with perpendicular magnetic anisotropy. The
+precession frequency shows large and systematic variation from about 5 GHz to
+about 90 GHz with the decrease in the Co layer thickness from 1.0 nm to 0.22 nm
+due to the linear increase in the perpendicular magnetic anisotropy. The
+damping coefficient 'alpha' is found to be inversely proportional to the Co
+layer thickness and a linear relation between the perpendicular magnetic
+anisotropy and 'alpha' is established. We discuss the possible reasons behind
+the enhanced damping as the d-d hybridization at the interface and spin
+pumping. These observations are significant for the applications of these
+materials in spintronics and magnonic crystals.",1106.4491v1
+2012-05-14,Critical viscoelastic response in jammed solids,"We determine the linear viscoelastic response of jammed packings of athermal
+repulsive viscous spheres, a model for emulsions, wet foams, and soft colloidal
+suspensions. We numerically measure the complex shear modulus, a fundamental
+characterization of the response, and demonstrate that low frequency response
+displays dynamic critical scaling near unjamming. Viscoelastic shear response
+is governed by the relaxational eigenmodes of a packing. We use scaling
+arguments to explain the distribution of eigenrates, which develops a
+divergence at unjamming. We then derive the critical exponents characterizing
+response, including a vanishing shear modulus, diverging viscosity, and
+critical shear thinning regime. Finally, we demonstrate that macroscopic
+rheology is sensitive to details of the local viscous force law. By varying the
+ratio of normal and tangential damping coefficients, we identify and explain a
+qualitative difference between systems with strong and weak damping of sliding
+motion. When sliding is weakly damped there is no diverging time scale, no
+diverging viscosity, and no critical shear thinning regime.",1205.2960v1
+2012-10-04,Basic microscopic plasma physics unified and simplified by N-body classical mechanics,"Debye shielding, collisional transport, Landau damping of Langmuir waves, and
+spontaneous emission of these waves are introduced, in typical plasma physics
+textbooks, in different chapters. This paper provides a compact unified
+introduction to these phenomena without appealing to fluid or kinetic models,
+but by using Newton's second law for a system of $N$ electrons in a periodic
+box with a neutralizing ionic background. A rigorous equation is derived for
+the electrostatic potential. Its linearization and a first smoothing reveal
+this potential to be the sum of the shielded Coulomb potentials of the
+individual particles. Smoothing this sum yields the classical Vlasovian
+expression including initial conditions in Landau contour calculations of
+Langmuir wave growth or damping. The theory is extended to accommodate a
+correct description of trapping or chaos due to Langmuir waves. In the linear
+regime, the amplitude of such a wave is found to be ruled by Landau growth or
+damping and by spontaneous emission. Using the shielded potential, the
+collisional diffusion coefficient is computed for the first time by a
+convergent expression including the correct calculation of deflections for all
+impact parameters. Shielding and collisional transport are found to be two
+related aspects of the repulsive deflections of electrons.",1210.1546v2
+2015-01-23,"Response solutions for quasi-periodically forced, dissipative wave equations","We consider several models of nonlinear wave equations subject to very strong
+damping and quasi-periodic external forcing. This is a singular perturbation,
+since the damping is not the highest order term. We study the existence of
+response solutions (i.e., quasi-periodic solutions with the same frequency as
+the forcing). Under very general non-resonance conditions on the frequency, we
+show the existence of asymptotic expansions of the response solution; moreover,
+we prove that the response solution indeed exists and depends analytically on
+$\varepsilon$ (where $\varepsilon$ is the inverse of the coefficient
+multiplying the damping) for $\varepsilon$ in a complex domain, which in some
+cases includes disks tangent to the imaginary axis at the origin. In other
+models, we prove analyticity in cones of aperture $\pi/2$ and we conjecture it
+is optimal. These results have consequences for the asymptotic expansions of
+the response solutions considered in the literature. The proof of our results
+relies on reformulating the problem as a fixed point problem, constructing an
+approximate solution and studying the properties of iterations that converge to
+the solutions of the fixed point problem.",1501.05979v1
+2015-05-08,Existence and general stabilization of the Timoshenko system with a thermo-viscoelastic damping and a delay term in the internal feedback,"In this paper, we consider a Timoshenko system with a thermo-viscoelastic
+damping and a delay term in the internal feedback together with initial datum
+and boundary conditions of Dirichlet type, where g is a positive non-increasing
+relaxation function and {\mu}1, {\mu}2 are positive constants. Under an
+hypothesis between the weight of the delay term in the feedback and the the
+weight of the friction damping term, using the Faedo-Galerkin approximations
+together with some energy estimates, we prove the global existence of the
+solutions. Then, by introducing appropriate Lyapunov functionals, under the
+imposed constrain on the weights of the two feedbacks and the coefficients, we
+establish the general energy decay result from which the exponential and
+polynomial types of decay are only special cases.",1505.01899v1
+2015-09-03,Stability analysis of degenerately-damped oscillations,"Presented here is a study of well-posedness and asymptotic stability of a
+""degenerately damped"" PDE modeling a vibrating elastic string. The coefficient
+of the damping may vanish at small amplitudes thus weakening the effect of the
+dissipation. It is shown that the resulting dynamical system has strictly
+monotonically decreasing energy and uniformly decaying lower-order norms,
+however, is not uniformly stable on the associated finite-energy space. These
+theoretical findings were motivated by numerical simulations of this model
+using a finite element scheme and successive approximations. A description of
+the numerical approach and sample plots of energy decay are supplied. In
+addition, for certain initial data the solution can be determined in closed
+form up to a dissipative nonlinear ordinary differential equation. Such
+solutions can be used to assess the accuracy of the numerical examples.",1509.00917v1
+2016-07-20,"Envelope equation for the linear and nonlinear propagation of an electron plasma wave, including the effects of Landau damping, trapping, plasma inhomogeneity, and the change in the state of wave","This paper addresses the linear and nonlinear three-dimensional propagation
+of an electron wave in a collisionless plasma that may be inhomogeneous,
+nonstationary, anisotropic and even weakly magnetized. The wave amplitude,
+together with any hydrodynamic quantity characterizing the plasma (density,
+temperature,...) are supposed to vary very little within one wavelength or one
+wave period. Hence, the geometrical optics limit is assumed, and the wave
+propagation is described by a first order differential equation. This equation
+explicitly accounts for three-dimensional effects, plasma inhomogeneity, Landau
+damping, and the collisionless dissipation and electron acceleration due to
+trapping. It is derived by mixing results obtained from a direct resolution of
+the Vlasov-Poisson system and from a variational formalism involving a nonlocal
+Lagrangian density. In a one-dimensional situation, abrupt transitions are
+predicted in the coefficients of the wave equation. They occur when the state
+of the electron plasma wave changes, from a linear wave to a wave with trapped
+electrons. In a three dimensional geometry, the transitions are smoother,
+especially as regards the nonlinear Landau damping rate, for which a very
+simple effective and accurate analytic expression is provided.",1607.05844v2
+2017-04-07,Underdamped stochastic harmonic oscillator,"We investigate stationary states of the linear damped stochastic oscillator
+driven by L\'evy noises. In the long time limit kinetic and potential energies
+of the oscillator do not fulfill the equipartition theorem and their
+distributions follow the power-law asymptotics. At the same time, partition of
+the mechanical energy is controlled by the damping coefficient. We show that in
+the limit of vanishing damping a stochastic analogue of the equipartition
+theorem can be proposed, namely the statistical properties of potential and
+kinetic energies attain distributions characterized by the same width. Finally,
+we demonstrate that the ratio of instantaneous kinetic and potential energies
+which signifies departure from the mechanical energy equipartition, follows
+universal power-law asymptotics.",1704.02119v2
+2017-08-30,Convergence to diffusion waves for solutions of Euler equations with time-depending damping on quadrant,"This paper is concerned with the asymptotic behavior of the solution to the
+Euler equations with time-depending damping on quadrant $(x,t)\in
+\mathbb{R}^+\times\mathbb{R}^+$, \begin{equation}\notag \partial_t v
+  -
+  \partial_x u=0, \qquad \partial_t u
+  +
+  \partial_x p(v)
+  =\displaystyle
+  -\frac{\alpha}{(1+t)^\lambda} u, \end{equation} with null-Dirichlet boundary
+condition or null-Neumann boundary condition on $u$. We show that the
+corresponding initial-boundary value problem admits a unique global smooth
+solution which tends time-asymptotically to the nonlinear diffusion wave.
+Compared with the previous work about Euler equations with constant coefficient
+damping, studied by Nishihara and Yang (1999, J. Differential Equations, 156,
+439-458), and Jiang and Zhu (2009, Discrete Contin. Dyn. Syst., 23, 887-918),
+we obtain a general result when the initial perturbation belongs to the same
+space. In addition, our main novelty lies in the facts that the cut-off points
+of the convergence rates are different from our previous result about the
+Cauchy problem. Our proof is based on the classical energy method and the
+analyses of the nonlinear diffusion wave.",1708.09127v1
+2018-01-23,The effect of liquid on the vibrational intensity of a wineglass at steady state resonance,"As a liquid is inserted into a wineglass, the natural frequency of the
+wineglass decreases. This phenomenon, known as pitch lowering, is well
+explained in past papers. However, previous literature have not yet mentioned
+that pitch lowering also reduces the resonance intensity of a wineglass. Thus,
+this present paper aims to extend the body of research on this topic by
+describing the relationship between pitch lowering and its effect on resonation
+intensity. To do so, we identify the vibrating wineglass wall as a damped
+harmonic oscillator, derive a theoretical model, and find that the resonance
+intensity of the wineglass is proportional to the square of its natural
+frequency, under the assumption that damping stays constant. However, our
+experiments showed the coefficient of damping to increase with respect to the
+amount of liquid, which caused the data to deviate from its theoretical
+predictions. We conclude by discussing the accuracy and limitation of our
+proposed model.",1801.07514v5
+2018-04-11,A global existence result for a semilinear wave equation with scale-invariant damping and mass in even space dimension,"In the present article a semilinear wave equation with scale-invariant
+damping and mass is considered. The global (in time) existence of radial
+symmetric solutions in even spatial dimension $n$ is proved using weighted
+$L^\infty-L^\infty$ estimates, under the assumption that the multiplicative
+constants, which appear in the coefficients of damping and of mass terms,
+fulfill an interplay condition which yields somehow a ""wave-like"" model. In
+particular, combining this existence result with a recently proved blow-up
+result, a suitable shift of Strauss exponent is proved to be the critical
+exponent for the considered model. Moreover, the still open part of a
+conjecture done by D'Abbicco - Lucente - Reissig is proved to be true in the
+massless case.",1804.03978v1
+2018-07-17,Boundary-to-Displacement Asymptotic Gains for Wave Systems With Kelvin-Voigt Damping,"We provide estimates for the asymptotic gains of the displacement of a
+vibrating string with endpoint forcing, modeled by the wave equation with
+Kelvin-Voigt and viscous damping and a boundary disturbance. Two asymptotic
+gains are studied: the gain in the L2 spatial norm and the gain in the spatial
+sup norm. It is shown that the asymptotic gain property holds in the L2 norm of
+the displacement without any assumption for the damping coefficients. The
+derivation of the upper bounds for the asymptotic gains is performed by either
+employing an eigenfunction expansion methodology or by means of a small-gain
+argument, whereas a novel frequency analysis methodology is employed for the
+derivation of the lower bounds for the asymptotic gains. The graphical
+illustration of the upper and lower bounds for the gains shows that that the
+asymptotic gain in the L2 norm is estimated much more accurately than the
+asymptotic gain in the sup norm.",1807.06549v1
+2018-07-24,Stabilization of an unstable wave equation using an infinite dimensional dynamic controller,"This paper deals with the stabilization of an anti-stable string equation
+with Dirichlet actuation where the instability appears because of the
+uncontrolled boundary condition. Then, infinitely many unstable poles are
+generated and an infinite dimensional control law is therefore proposed to
+exponentially stabilize the system. The idea behind the choice of the
+controller is to extend the domain of the PDE so that the anti-damping term is
+compensated by a damping at the other boundary condition. Additionally, notice
+that the system can then be exponentially stabilized with a chosen decay-rate
+and is robust to uncertainties on the wave speed and the anti-damped
+coefficient of the wave equation, with the only use of a point-wise boundary
+measurement. The efficiency of this new control strategy is then compared to
+the backstepping approach.",1807.08999v2
+2018-08-30,The influence of the coefficients of a system of coupled wave equations with fractional damping on its stabilization,"In this work, we consider a system of two wave equations coupled by
+velocities in one-dimensional space, with one boundary fractional damping.
+First, we show that the system is strongly asymptotically stable if and only if
+the coupling parameter b of the two equations is outside a discrete set of
+exceptional real values. Next, we show that our system is not uniformly stable.
+Hence, we look for a polynomial decay rate for smooth initial data. Using
+frequency domain approach combining with multiplier method, we prove that the
+energy decay rate is greatly influenced by the nature of the coupling parameter
+b, the arithmetic property of the ratio of the wave propagation speeds a, the
+order of the fractional damping. Indeed, under the equal speed propagation
+condition, we establish an optimal polynomial energy decay rate. Furthermore,
+when the wave propagate with different speeds, under some arithmetic conditions
+on the ratio of the wave propagation speeds, we prove that the energy of our
+system decays polynomially to zero.",1808.10285v4
+2019-06-10,Global existence of weak solutions to the compressible quantum Navier-Stokes equations with degenerate viscosity,"We study the compressible quantum Navier-Stokes (QNS) equations with
+degenerate viscosity in the three dimensional periodic domains. On the one
+hand, we consider QNS with additional damping terms. Motivated by the recent
+works [Li-Xin, arXiv:1504.06826] and [Antonelli-Spirito, Arch. Ration. Mech.
+Anal., 203(2012), 499--527], we construct a suitable approximate system which
+has smooth solutions satisfying the energy inequality and the BD entropy
+estimate. Using this system, we obtain the global existence of weak solutions
+to the compressible QNS equations with damping terms for large initial data.
+Moreover, we obtain some new a priori estimates, which can avoid using the
+assumption that the gradient of the velocity is a well-defined function, which
+is indeed used directly in [Vasseur-Yu, SIAM J. Math. Anal., 48 (2016),
+1489--1511; Invent. Math., 206 (2016), 935--974]. On the other hand, in the
+absence of damping terms, we also prove the global existence of weak solutions
+to the compressible QNS equations without the lower bound assumption on the
+dispersive coefficient, which improves the previous result due to
+[Antonelli-Spirito, Arch. Ration. Mech. Anal., 203(2012), 499--527].",1906.03971v1
+2019-08-19,Time Delay in the Swing Equation: A Variety of Bifurcations,"The present paper addresses the swing equation with additional delayed
+damping as an example for pendulum-like systems. In this context, it is proved
+that recurring sub- and supercritical Hopf bifurcations occur if time delay is
+increased. To this end, a general formula for the first Lyapunov coefficient in
+second order systems with additional delayed damping and delay-free
+nonlinearity is given. In so far the paper extends results about stability
+switching of equilibria in linear time delay systems from Cooke and Grossman.
+In addition to the analytical results, periodic solutions are numerically dealt
+with. The numerical results demonstrate how a variety of qualitative behaviors
+is generated in the simple swing equation by only introducing time delay in a
+damping term.",1908.07996v3
+2019-12-30,A Link Between Relativistic Rest Energy and Fractionary Momentum Operators of Order 1/2,"The solution of a causal fractionary wave equation in an infinite potential
+well was obtained. First, the so-called ""free particle"" case was solved, giving
+as normalizable solutions a superposition of damped oscillations similar to a
+wave packet. From this results, the infinite potential well case was then
+solved. The damping coefficient of the equation obtained was matched with the
+exponent appearing in the Yucawa potential or ""screened"" Coulomb potential.
+When this matching was forced, the particle aquires an offset energy of E =
+mc^2/2 which then can be increased by each energy level. The expontential
+damping of the wave solutions in the box was found to be closely related with
+the radius of the proton when the particle has a mass equal to the mass of the
+proton. Lastly the fractionary wave equation was expressed in spherical
+coordinates and remains to be solved through analytical or numerical methods.",1912.12770v4
+2020-08-18,Singularity formation for compressible Euler equations with time-dependent damping,"In this paper, we consider the compressible Euler equations with
+time-dependent damping \frac{\a}{(1+t)^\lambda}u in one space dimension. By
+constructing 'decoupled' Riccati type equations for smooth solutions, we
+provide some sufficient conditions under which the classical solutions must
+break down in finite time. As a byproduct, we show that the derivatives blow
+up, somewhat like the formation of shock wave, if the derivatives of initial
+data are appropriately large at a point even when the damping coefficient goes
+to infinity with a algebraic growth rate. We study the case \lambda\neq1 and
+\lambda=1 respectively, moreover, our results have no restrictions on the size
+of solutions and the positivity/monotonicity of the initial Riemann invariants.
+In addition, for 1<\gamma<3 we provide time-dependent lower bounds on density
+for arbitrary classical solutions, without any additional assumptions on the
+initial data.",2008.07756v1
+2020-11-14,Learning a Reduced Basis of Dynamical Systems using an Autoencoder,"Machine learning models have emerged as powerful tools in physics and
+engineering. Although flexible, a fundamental challenge remains on how to
+connect new machine learning models with known physics. In this work, we
+present an autoencoder with latent space penalization, which discovers finite
+dimensional manifolds underlying the partial differential equations of physics.
+We test this method on the Kuramoto-Sivashinsky (K-S), Korteweg-de Vries (KdV),
+and damped KdV equations. We show that the resulting optimal latent space of
+the K-S equation is consistent with the dimension of the inertial manifold. The
+results for the KdV equation imply that there is no reduced latent space, which
+is consistent with the truly infinite dimensional dynamics of the KdV equation.
+In the case of the damped KdV equation, we find that the number of active
+dimensions decreases with increasing damping coefficient. We then uncover a
+nonlinear basis representing the manifold of the latent space for the K-S
+equation.",2011.07346v1
+2021-01-11,Damped (linear) response theory within the resolution-of-identity coupled cluster singles and approximate doubles (RI-CC2) method,"An implementation of a complex solver for the solution of the response
+equations required to compute the complex response functions of damped response
+theory is presented for the resolution-of-identity (RI) coupled-cluster singles
+and approximate doubles CC2 method. The implementation uses a partitioned
+formulation that avoids the storage of double excitation amplitudes to make it
+applicable to large molecules. The solver is the keystone element for the
+development of the damped coupled-cluster response formalism for linear and
+nonlinear effects in resonant frequency regions at the RI-CC2 level of theory.
+Illustrative results are reported for the one-photon absorption cross section
+of C60, the electronic circular dichroism of $n$-helicenes ($n$ = 5, 6, 7), and
+the $C_6$ dispersion coefficients of a set of selected organic molecules and
+fullerenes.",2101.03756v1
+2021-06-24,Landau damping of electron-acoustic waves due to multi-plasmon resonances,"The linear and nonlinear theories of electron-acoustic waves (EAWs) are
+studied in a partially degenerate quantum plasma with two-temperature electrons
+and stationary ions. The initial equilibrium of electrons is assumed to be
+given by the Fermi-Dirac distribution at finite temperature. By employing the
+multi-scale asymptotic expansion technique to the one-dimensional Wigner-Moyal
+and Poisson equations, it is shown that the effects of multi-plasmon resonances
+lead to a modified complex Korteweg-de Vries (KdV) equation with a new nonlocal
+nonlinearity. Besides giving rise to a nonlocal nonlinear term, the
+wave-particle resonance also modifies the local nonlinear coupling coefficient
+of the KdV equation. The latter is shown to conserve the number of particles,
+however, the wave energy decays with time. A careful analysis shows that the
+two-plasmon resonance is the dominant mechanism for nonlinear Landau damping of
+EAWs. An approximate soliton solution of the KdV equation is also obtained, and
+it is shown that the nonlinear Landau damping causes the wave amplitude to
+decay slowly with time compared to the classical theory.",2106.12754v2
+2021-08-12,The damping and diffusion of atoms moving in the background electromagnetic environment,"The interaction between an atom and the quantized electromagnetic field
+depends on the position of the atom. Then the atom experiences a force which is
+the minus gradient of this interaction. Through the Heisenberg equations of
+motion and the Born-Markov approximation, the mean and correlation of the force
+are obtained, showing that the center-of-mass motion of the atom is damped and
+diffused. This approach can be easily generalized to multi-level atoms, where
+the damping force and diffusion coefficients are just the weighted average of
+the contributions from all pairs of energy levels that have nonvanishing dipole
+elements. It is shown that these results are invariant under Galilean
+transformation, and in principle can be used to determine the velocity of the
+lab relative to the background radiation.",2108.05590v3
+2021-11-18,Sharp Stability of a String with Local Degenerate Kelvin-Voigt Damping,"This paper is on the asymptotic behavior of the elastic string equation with
+localized degenerate Kelvin--Voigt damping $$
+u_{tt}(x,t)-[u_{x}(x,t)+b(x)u_{x,t}(x,t)]_{x}=0,\; x\in(-1,1),\; t>0,$$ where
+$b(x)=0$ on $x\in (-1,0]$, and $b(x)=x^\alpha>0$ on $x\in (0,1)$ for
+$\alpha\in(0,1)$. It is known that the optimal decay rate of solution is
+$t^{-2}$ in the limit case $\alpha=0$, and exponential decay rate for
+$\alpha\ge 1$. When $\alpha\in (0,1)$, the damping coefficient $b(x)$ is
+continuous, but its derivative has a singularity at the interface $x=0$. In
+this case, the best known decay rate is $t^{-\frac{3-\alpha}{2(1-\alpha)}}$.
+Although this rate is consistent with the exponential one at $\alpha=1$, it
+failed to match the optimal one at $\alpha=0$.
+  In this paper, we obtain a sharper polynomial decay rate
+$t^{-\frac{2-\alpha}{1-\alpha}}$. More significantly, it is consistent with the
+optimal polynomial decay rate at $\alpha=0$ and the exponential decay rate at
+$\alpha = 1$.This is a big step toward the goal of obtaining eventually the
+optimal decay rate.",2111.09500v1
+2021-11-26,Damping of Pseudo-Goldstone Fields,"Approximate symmetries abound in Nature. If these symmetries are also
+spontaneously broken, the would-be Goldstone modes acquire a small mass, or
+inverse correlation length, and are referred to as pseudo-Goldstones. At
+nonzero temperature, the effects of dissipation can be captured by
+hydrodynamics at sufficiently long scales compared to the local equilibrium.
+Here we show that in the limit of weak explicit breaking, locality of
+hydrodynamics implies that the damping of pseudo-Goldstones is completely
+determined by their mass and diffusive transport coefficients. We present many
+applications: superfluids, QCD in the chiral limit, Wigner crystal and density
+wave phases in the presence of an external magnetic field or not, nematic
+phases and (anti-)ferromagnets. For electronic density wave phases,
+pseudo-Goldstone damping generates a contribution to the resistivity
+independent of the strength of disorder, which can have a linear temperature
+dependence provided the associated diffusivity saturates a bound. This is
+reminiscent of the phenomenology of strange metal high $T_c$ superconductors,
+where charge density waves are observed across the phase diagram.",2111.13459v2
+2023-06-26,"Blow-up result for a weakly coupled system of wave equations with a scale-invariant damping, mass term and time derivative nonlinearity","We study in this article the blow-up of solutions to a coupled semilinear
+wave equations which are characterized by linear damping terms in the
+\textit{scale-invariant regime}, time-derivative nonlinearities, mass terms and
+Tricomi terms. The latter are specifically of great interest from both physical
+and mathematical points of view since they allow the speeds of propagation to
+be time-dependent ones. However, we assume in this work that both waves are
+propagating with the same speeds. Employing this fact together with other
+hypotheses on the aforementioned parameters (mass and damping coefficients), we
+obtain a new blow-up region for the system under consideration, and we show a
+lifespan estimate of the maximal existence time.",2306.14768v1
+2010-03-11,Damping of MHD turbulence in partially ionized gas and the observed difference of velocities of neutrals and ions,"Theoretical and observational studies on the turbulence of the interstellar
+medium developed fast in the past decades. The theory of supersonic magnetized
+turbulence, as well as the understanding of projection effects of observed
+quantities, are still in progress. In this work we explore the characterization
+of the turbulent cascade and its damping from observational spectral line
+profiles. We address the difference of ion and neutral velocities by clarifying
+the nature of the turbulence damping in the partially ionized. We provide
+theoretical arguments in favor of the explanation of the larger Doppler
+broadening of lines arising from neutral species compared to ions as arising
+from the turbulence damping of ions at larger scales. Also, we compute a number
+of MHD numerical simulations for different turbulent regimes and explicit
+turbulent damping, and compare both the 3-dimensional distributions of velocity
+and the synthetic line profile distributions. From the numerical simulations,
+we place constraints on the precision with which one can measure the 3D
+dispersion depending on the turbulence sonic Mach number. We show that no
+universal correspondence between the 3D velocity dispersions measured in the
+turbulent volume and minima of the 2D velocity dispersions available through
+observations exist. For instance, for subsonic turbulence the correspondence is
+poor at scales much smaller than the turbulence injection scale, while for
+supersonic turbulence the correspondence is poor for the scales comparable with
+the injection scale. We provide a physical explanation of the existence of such
+a 2D-3D correspondence and discuss the uncertainties in evaluating the damping
+scale of ions that can be obtained from observations. However, we show that the
+statistics of velocity dispersion from observed line profiles can provide the
+spectral index and the energy transfer rate of turbulence. Also, comparing two
+similar simulations with different viscous coefficients it was possible to
+constrain the turbulent cut-off scale. This may especially prove useful since
+it is believed that ambipolar diffusion may be one of the dominant dissipative
+mechanism in star-forming regions. In this case, the determination of the
+ambipolar diffusion scale may be used as a complementary method for the
+determination of magnetic field intensity in collapsing cores. We discuss the
+implications of our findings in terms of a new approach to magnetic field
+measurement proposed by Li & Houde (2008).",1003.2346v1
+2012-11-06,Torsional Alfvén waves in solar partially ionized plasma: effects of neutral helium and stratification,"Ion-neutral collisions may lead to the damping of Alfven waves in
+chromospheric and prominence plasmas. Neutral helium atoms enhance the damping
+in certain temperature interval, where the ratio of neutral helium and neutral
+hydrogen atoms is increased. Therefore, the height-dependence of ionization
+degrees of hydrogen and helium may influence the damping rate of Alfven waves.
+We aim to study the effect of neutral helium in the damping of Alfven waves in
+stratified partially ionized plasma of the solar chromosphere. We consider a
+magnetic flux tube, which is expanded up to 1000 km height and then becomes
+vertical due to merging with neighboring tubes, and study the dynamics of
+linear torsional Alfven waves in the presence of neutral hydrogen and neutral
+helium atoms. We start with three-fluid description of plasma and consequently
+derive single-fluid magnetohydrodynamic (MHD) equations for torsional Alfven
+waves. Thin flux tube approximation allows to obtain the dispersion relation of
+the waves in the lower part of tubes, while the spatial dependence of
+steady-state Alfven waves is governed by Bessel type equation in the upper part
+of tubes. Consecutive derivation of single-fluid MHD equations results in a new
+Cowling diffusion coefficient in the presence of neutral helium which is
+different from previously used one. We found that shorter-period (< 5 s)
+torsional Alfven waves damp quickly in the chromospheric network due to
+ion-neutral collision. On the other hand, longer-period (> 5 s) waves do not
+reach the transition region as they become evanescent at lower heights in the
+network cores. Propagation of torsional Alfven waves through the chromosphere
+into the solar corona should be considered with caution: low-frequency waves
+are evanescent due to the stratification, while high-frequency waves are damped
+due to ion neutral collisions.",1211.1348v2
+1999-05-29,Theory of Hall Effect and Electrical Transport in High-Tc Cuprates: Effects of Antiferromagnetic Spin Fluctuations,"In the normal state of high-Tc cuprates, the Hall coefficient shows
+remarkable temperature dependence, and its absolute value is enhanced in
+comparison with that value simply estimated on the basis of band structure. It
+has been recognized that this temperature dependence of the Hall coefficient is
+due to highly anisotropic quasiparticle damping rate on the Fermi surface. In
+this paper we further take account of the vertex correction to the current
+vertex arising from quasiparticle interactions. Then the transport current is
+transformed to a large extent from the quasiparticle velocity, and is no longer
+proportional to the latter. As a consequence some pieces of the Fermi surface
+outside of the antiferromagnetic Brillouin zone make negative contribution to
+the Hall conductivity, even if the curvature of the Fermi surface is hole-like.
+The Hall coefficient is much larger at low temperatures than the estimate made
+without the vertex correction. Temperature dependence of the antiferromagnetic
+spin correlation length is also crucial to cause remarkable temperature
+dependence of the Hall coefficient. In our treatment the Hall coefficient of
+the electron-doped cuprates can be negative despite hole-like curvature of the
+Fermi surface.",9905428v1
+2021-06-02,In-medium kinetic theory of $D$ mesons and heavy-flavor transport coefficients,"We extend the kinetic theory of $D$ mesons to accommodate thermal and
+off-shell effects due to the medium modification of the heavy-meson spectral
+functions. From the Kadanoff-Baym approach we derive the off-shell
+Fokker-Planck equation which encodes the heavy-flavor transport coefficients.
+We analyze the thermal width (damping rate) of $D$ mesons due to their
+scattering off light mesons, focusing on new in-medium effects: off-shell
+corrections, inelastic channels, and the contribution of the Landau cut. We
+obtain that the latter effect (absent for vacuum scattering amplitudes) brings
+sizable corrections at moderate temperatures. We discuss how the heavy-flavor
+transport coefficients, like the drag and diffusion coefficients, are modified
+in matter. We find that the $D$-meson spatial diffusion coefficient matches
+smoothly to the latest results of lattice-QCD calculations and Bayesian
+analyses at higher temperatures.",2106.01156v2
+2022-04-08,Transport coefficients of heavy quarkonia comparing with heavy quark coefficients,"We revisit the transport coefficients of heavy quarkonia moving in
+high-temperature QCD plasmas. The thermal width and mass shift for heavy
+quarkonia are closely related to the momentum diffusion coefficient and its
+dispersive counterpart for heavy quarks, respectively. For quarkonium at rest
+in plasmas the longitudinal gluon part of the color-singlet self-energy diagram
+is sufficient to determine the leading-order thermal width, whereas the
+momentum dependence is obtained from the transverse gluon channel. Using the
+quarkonium-gluon effective vertex based on the dipole interaction of color
+charges, we discuss the damping rate, the effective rest and kinetic mass
+shifts of slowly moving quarkonia and compare with the corresponding
+coefficients of heavy quarks.",2204.04180v1
+2006-06-15,Purity and decoherence in the theory of a damped harmonic oscillator,"For the generalized master equations derived by Karrlein and Grabert for the
+microscopic model of a damped harmonic oscillator, the conditions for purity of
+states are written, in particular for different initial conditions and
+different types of damping, including Ohmic, Drude and weak coupling cases,
+Agarwal and Weidlich-Haake models. It is shown that the states which remain
+pure are the squeezed states with constant in time variances. For pure states,
+the generalized nonlinear Schr\"" odinger-type equations corresponding to these
+master equations are also obtained. Then the condition for purity of states of
+a damped harmonic oscillator is considered in the framework of Lindblad theory
+for open quantum systems. For a special choice of the environment coefficients,
+the correlated coherent states with constant variances and covariance are shown
+to be the only states which remain pure all the time during the evolution of
+the considered system. In Karrlein-Grabert and Lindblad models, as well as in
+the considered particular models, the expressions of the rate of entropy
+production is written and it is shown that the states which preserve their
+purity in time are also the states which minimize the entropy production and,
+therefore, they are the most stable ones under evolution in the presence of the
+environment and play an important role in the description of decoherence
+phenomenon.",0606134v1
+2009-10-09,One-way coupled Van der Pol system,"The equation of the Van der Pol oscillator, being characterized by a
+dissipative term, is non-Lagrangian. Appending an additional degree of freedom
+we bring the equation in the frame of action principle and thus introduce a
+one-way coupled system. As with the Van der Pol oscillator, the coupled system
+also involves only one parameter that controls the dynamics. The response
+system is described by a linear differential equation coupled nonlinearly to
+the drive system. In the linear approximation the equations of our coupled
+system coincide with those of the Bateman dual system (a pair of damped and
+anti-damped harmonic oscillators). The critical point of damped and anti-damped
+oscillators are stable and unstable for all physical values of the frictional
+coefficient $\mu$. Contrarily, the critical points of the drive- (Van der Pol)
+and response systems depend crucially on the values of $\mu$. These points are
+unstable for $\mu > 0$ while the critical point of the drive system is stable
+and that of the response system is unstable for $\mu < 0$. The one-way coupled
+system exhibits bifurcations which are different from those of the uncoupled
+Van der Pol oscillator. Our system is chaotic and we observe phase
+synchronization in the regime of dynamic chaos only for small values of $\mu$.",0910.1700v1
+2018-02-18,On energy stable discontinuous Galerkin spectral element approximations of the perfectly matched layer for the wave equation,"We develop a provably energy stable discontinuous Galerkin spectral element
+method (DGSEM) approximation of the perfectly matched layer (PML) for the three
+and two space dimensional (3D and 2D) linear acoustic wave equations, in first
+order form, subject to well-posed linear boundary conditions. First, using the
+well-known complex coordinate stretching, we derive an efficient un-split modal
+PML for the 3D acoustic wave equation. Second, we prove asymptotic stability of
+the continuous PML by deriving energy estimates in the Laplace space, for the
+3D PML in a heterogeneous acoustic medium, assuming piece-wise constant PML
+damping. Third, we develop a DGSEM for the wave equation using physically
+motivated numerical flux, with penalty weights, which are compatible with all
+well-posed, internal and external, boundary conditions. When the PML damping
+vanishes, by construction, our choice of penalty parameters yield an upwind
+scheme and a discrete energy estimate analogous to the continuous energy
+estimate. Fourth, to ensure numerical stability when PML damping is present, it
+is necessary to systematically extend the numerical numerical fluxes, and the
+inter-element and boundary procedures, to the PML auxiliary differential
+equations. This is critical for deriving discrete energy estimates analogous to
+the continuous energy estimates. Finally, we propose a procedure to compute PML
+damping coefficients such that the PML error converges to zero, at the optimal
+convergence rate of the underlying numerical method. Numerical experiments are
+presented in 2D and 3D corroborating the theoretical results.",1802.06388v1
+2018-09-19,Critical exponent for the semilinear wave equations with a damping increasing in the far field,"We consider the Cauchy problem of the semilinear wave equation with a damping
+term \begin{align*}
+  u_{tt} - \Delta u + c(t,x) u_t = |u|^p, \quad (t,x)\in (0,\infty)\times
+\mathbb{R}^N,\quad
+  u(0,x) = \varepsilon u_0(x), \ u_t(0,x) = \varepsilon u_1(x), \quad x\in
+\mathbb{R}^N, \end{align*} where $p>1$ and the coefficient of the damping term
+has the form \begin{align*}
+  c(t,x) = a_0 (1+|x|^2)^{-\alpha/2} (1+t)^{-\beta} \end{align*} with some $a_0
+> 0$, $\alpha < 0$, $\beta \in (-1, 1]$. In particular, we mainly consider the
+cases $ \alpha < 0, \beta =0$ or $\alpha < 0, \beta = 1$, which imply $\alpha +
+\beta < 1$, namely, the damping is spatially increasing and effective. Our aim
+is to prove that the critical exponent is given by $ p = 1+
+\frac{2}{N-\alpha}$. This shows that the critical exponent is the same as that
+of the corresponding parabolic equation $c(t,x) v_t - \Delta v = |v|^p$. The
+global existence part is proved by a weighted energy estimates with an
+exponential-type weight function and a special case of the
+Caffarelli-Kohn-Nirenberg inequality. The blow-up part is proved by a
+test-function method introduced by Ikeda and Sobajima (arXiv:1710.06780v1). We
+also give an upper estimate of the lifespan.",1809.06994v1
+2020-08-03,Improvement on the blow-up of the wave equation with the scale-invariant damping and combined nonlinearities,"We consider in this article the damped wave equation, in the
+\textit{scale-invariant case} with combined two nonlinearities, which reads as
+follows: \begin{displaymath} \d (E) \hspace{1cm} u_{tt}-\Delta
+u+\frac{\mu}{1+t}u_t=|u_t|^p+|u|^q, \quad \mbox{in}\ \R^N\times[0,\infty),
+\end{displaymath} with small initial data.\\ Compared to our previous work
+\cite{Our}, we show in this article that the first hypothesis on the damping
+coefficient $\mu$, namely $\mu < \frac{N(q-1)}{2}$, can be removed, and the
+second one can be extended from $(0, \mu_*/2)$ to $(0, \mu_*)$ where $\mu_*>0$
+is solution of $(q-1)\left((N+\mu_*-1)p-2\right) = 4$. Indeed, owing to a
+better understanding of the influence of the damping term in the global
+dynamics of the solution, we think that this new interval for $\mu$ describe
+better the threshold between the blow-up and the global existence regions.
+Moreover, taking advantage of the techniques employed in the problem $(E)$, we
+also improve the result in \cite{LT2,Palmieri} in relationship with the Glassey
+conjecture for the solution of $(E)$ but without the nonlinear term $|u|^q$.
+More precisely, we extend the blow-up region from $p \in (1, p_G(N+\sigma)]$,
+where $\sigma$ is given by \eqref{sigma} below, to $p \in (1, p_G(N+\mu)]$
+giving thus a better estimate of the lifespan in this case.",2008.02109v3
+2021-07-17,Theoretical and numerical study of vibrational resonance in a damped softening Duffing oscillator,"We study the possibility of occurrence of vibrational resonance in a
+softening Duffing oscillator in the underdamped and overdamped cases both
+theoretically as well as numerically. The oscillator is driven by two periodic
+forces. Numerically we find that in the underdamped case two oscillatory
+solutions are obtained in a limited range of the parameters considered (damping
+coefficient and amplitude of the high frequency force) for a fixed frequency
+and amplitude of the low frequency periodic force depending on the initial
+conditions. These solutions have distinct response amplitude to the low
+frequency force. When damping is gradually increased, only one oscillatory
+solution is observed. Vibrational resonance is observed in both the regions of
+oscillation. The analytical approximation yields only one oscillatory solution
+for all damping values. Analytically, the peak in the area bounded by the phase
+portrait as a function of the amplitude of the high frequency force is
+connected to vibrational resonance. Also, the values of the frequency of the
+low frequency forcing and the amplitude of the high frequency forcing at which
+vibrational resonance is found to occur are obtained. In the overdamped case,
+vibrational resonance is not observed for the softening Duffing oscillator thus
+showing a marked contrast to the overdamped bistable oscillator",2107.08302v1
+2021-11-15,"Convergence Analysis of A Second-order Accurate, Linear Numerical Scheme for The Landau-Lifshitz Equation with Large Damping Parameters","A second order accurate, linear numerical method is analyzed for the
+Landau-Lifshitz equation with large damping parameters. This equation describes
+the dynamics of magnetization, with a non-convexity constraint of unit length
+of the magnetization. The numerical method is based on the second-order
+backward differentiation formula in time, combined with an implicit treatment
+of the linear diffusion term and explicit extrapolation for the nonlinear
+terms. Afterward, a projection step is applied to normalize the numerical
+solution at a point-wise level. This numerical scheme has shown extensive
+advantages in the practical computations for the physical model with large
+damping parameters, which comes from the fact that only a linear system with
+constant coefficients (independent of both time and the updated magnetization)
+needs to be solved at each time step, and has greatly improved the numerical
+efficiency. Meanwhile, a theoretical analysis for this linear numerical scheme
+has not been available. In this paper, we provide a rigorous error estimate of
+the numerical scheme, in the discrete $\ell^{\infty}(0,T; \ell^2) \cap
+\ell^2(0,T; H_h^1)$ norm, under suitable regularity assumptions and reasonable
+ratio between the time step-size and the spatial mesh-size. In particular, the
+projection operation is nonlinear, and a stability estimate for the projection
+step turns out to be highly challenging. Such a stability estimate is derived
+in details, which will play an essential role in the convergence analysis for
+the numerical scheme, if the damping parameter is greater than 3.",2111.07537v1
+2022-12-22,Spin wave dispersion of ultra-low damping hematite ($α\text{-Fe}_2\text{O}_3$) at GHz frequencies,"Low magnetic damping and high group velocity of spin waves (SWs) or magnons
+are two crucial parameters for functional magnonic devices. Magnonics research
+on signal processing and wave-based computation at GHz frequencies focussed on
+the artificial ferrimagnetic garnet Y$_3$Fe$_5$O$_{12}$ (YIG) so far. We report
+on spin-wave spectroscopy studies performed on the natural mineral hematite
+($\alpha\text{-Fe}_2\text{O}_3$) which is a canted antiferromagnet. By means of
+broadband GHz spectroscopy and inelastic light scattering, we determine a
+damping coefficient of $1.1\times10^{-5}$ and magnon group velocities of a few
+10 km/s, respectively, at room temperature. Covering a large regime of wave
+vectors up to $k\approx 24~{\rm rad}/\mu$m, we find the exchange stiffness
+length to be relatively short and only about 1 \r{A}. In a small magnetic field
+of 30 mT, the decay length of SWs is estimated to be 1.1 cm similar to the best
+YIG. Still, inelastic light scattering provides surprisingly broad and partly
+asymmetric resonance peaks. Their characteristic shape is induced by the large
+group velocities, low damping and distribution of incident angles inside the
+laser beam. Our results promote hematite as an alternative and sustainable
+basis for magnonic devices with fast speeds and low losses based on a stable
+natural mineral.",2212.11887v2
+2024-02-19,Global existence for non-homogeneous incompressible inviscid fluids in presence of Ekman pumping,"In this paper, we study the global solvability of the density-dependent
+incompressible Euler equations, supplemented with a damping term of the form $
+\mathfrak{D}_{\alpha}^{\gamma}(\rho, u) = \alpha \rho^{\gamma} u $, where
+$\alpha>0$ and $ \gamma \in \{0,1\} $. To some extent, this system can be seen
+as a simplified model describing the mean dynamics in the ocean; from this
+perspective, the damping term can be interpreted as a term encoding the effects
+of the celebrated Ekman pumping in the system.
+  On the one hand, in the general case of space dimension $d\geq 2$, we
+establish global well-posedness in the Besov spaces framework, under a
+non-linear smallness condition involving the size of the initial velocity field
+$u_0$, of the initial non-homogeneity $\rho_0-1$ and of the damping coefficient
+$\alpha$. On the other hand, in the specific situation of planar motions and
+damping term with $\gamma=1$, we exhibit a second smallness condition implying
+global existence, which in particular yields global well-posedness for
+arbitrarily large initial velocity fields, provided the initial density
+variations $\rho_0-1$ are small enough. The formulated smallness conditions
+rely only on the endpoint Besov norm $B^1_{\infty,1}$ of the initial datum,
+whereas, as a byproduct of our analysis, we derive exponential decay of the
+velocity field and of the pressure gradient in the high regularity norms
+$B^s_{p,r}$.",2402.12592v1
+1993-04-01,Wavelet transforms versus Fourier transforms,"This note is a very basic introduction to wavelets. It starts with an
+orthogonal basis of piecewise constant functions, constructed by dilation and
+translation. The ``wavelet transform'' maps each $f(x)$ to its coefficients
+with respect to this basis. The mathematics is simple and the transform is fast
+(faster than the Fast Fourier Transform, which we briefly explain), but
+approximation by piecewise constants is poor. To improve this first wavelet, we
+are led to dilation equations and their unusual solutions. Higher-order
+wavelets are constructed, and it is surprisingly quick to compute with them ---
+always indirectly and recursively. We comment informally on the contest between
+these transforms in signal processing, especially for video and image
+compression (including high-definition television). So far the Fourier
+Transform --- or its 8 by 8 windowed version, the Discrete Cosine Transform ---
+is often chosen. But wavelets are already competitive, and they are ahead for
+fingerprints. We present a sample of this developing theory.",9304214v1
+2008-01-07,Magnetization reversal driven by spin-injection : a mesoscopic spin-transfer effect,"A mesoscopic description of spin-transfer effect is proposed, based on the
+spin-injection mechanism occurring at the junction with a ferromagnet. The
+effect of spin-injection is to modify locally, in the ferromagnetic
+configuration space, the density of magnetic moments. The corresponding
+gradient leads to a current-dependent diffusion process of the magnetization.
+In order to describe this effect, the dynamics of the magnetization of a
+ferromagnetic single domain is reconsidered in the framework of the
+thermokinetic theory of mesoscopic systems. Assuming an Onsager
+cross-coefficient that couples the currents, it is shown that spin-dependent
+electric transport leads to a correction of the Landau-Lifshitz-Gilbert
+equation of the ferromagnetic order parameter with supplementary diffusion
+terms. The consequence of spin-injection in terms of activation process of the
+ferromagnet is deduced, and the expressions of the effective energy barrier and
+of the critical current are derived. Magnetic fluctuations are calculated: the
+correction to the fluctuations is similar to that predicted for the activation.
+These predictions are consistent with the measurements of spin-transfer
+obtained in the activation regime and for ferromagnetic resonance under
+spin-injection.",0801.1019v1
+2012-07-24,Bulk Topological Invariants in Noninteracting Point Group Symmetric Insulators,"We survey various quantized bulk physical observables in two- and
+three-dimensional topological band insulators invariant under translational
+symmetry and crystallographic point group symmetries (PGS). In two-dimensional
+insulators, we show that: (i) the Chern number of a $C_n$-invariant insulator
+can be determined, up to a multiple of $n$, by evaluating the eigenvalues of
+symmetry operators at high-symmetry points in the Brillouin zone; (ii) the
+Chern number of a $C_n$-invariant insulator is also determined, up to a
+multiple of $n$, by the $C_n$ eigenvalue of the Slater determinant of a
+noninteracting many-body system and (iii) the Chern number vanishes in
+insulators with dihedral point groups $D_n$, and the quantized electric
+polarization is a topological invariant for these insulators. In
+three-dimensional insulators, we show that: (i) only insulators with point
+groups $C_n$, $C_{nh}$ and $S_n$ PGS can have nonzero 3D quantum Hall
+coefficient and (ii) only insulators with improper rotation symmetries can have
+quantized magnetoelectric polarization $P_3$ in the term
+$P_3\mathbf{E}\cdot\mathbf{B}$, the axion term in the electrodynamics of the
+insulator (medium).",1207.5767v2
+2016-08-06,"High current, high efficiency graded band gap perovskite solar cells","Organic-inorganic halide perovskite materials have emerged as attractive
+alternatives to conventional solar cell building blocks. Their high light
+absorption coefficients and long diffusion lengths suggest high power
+conversion efficiencies (PCE),1-5 and indeed perovskite-based single band gap
+and tandem solar cell designs have yielded impressive performances.1-16 One
+approach to further enhance solar spectrum utilization is the graded band gap,
+but this has not been previously achieved for perovskites. In this study, we
+demonstrate graded band gap perovskite solar cells with steady-state conversion
+efficiencies averaging 18.4%, with a best of 21.7%, all without reflective
+coatings. An analysis of the experimental data yields high fill factors of ~75%
+and high short circuit current densities up to 42.1 mA/cm2. These cells, which
+are based on a novel architecture of two perovskite layers (MASnI3 and
+MAPbI3-xBrx), incorporating GaN, monolayer hexagonal boron nitride, and
+graphene aerogel, display the highest efficiency ever reported for perovskite
+solar cells.",1608.02150v1
+2016-08-30,LiRa: A New Likelihood-Based Similarity Score for Collaborative Filtering,"Recommender system data presents unique challenges to the data mining,
+machine learning, and algorithms communities. The high missing data rate, in
+combination with the large scale and high dimensionality that is typical of
+recommender systems data, requires new tools and methods for efficient data
+analysis. Here, we address the challenge of evaluating similarity between two
+users in a recommender system, where for each user only a small set of ratings
+is available. We present a new similarity score, that we call LiRa, based on a
+statistical model of user similarity, for large-scale, discrete valued data
+with many missing values. We show that this score, based on a ratio of
+likelihoods, is more effective at identifying similar users than traditional
+similarity scores in user-based collaborative filtering, such as the Pearson
+correlation coefficient. We argue that our approach has significant potential
+to improve both accuracy and scalability in collaborative filtering.",1608.08646v2
+2018-11-01,Time Quantified Monte Carlo Method for Long-range Interacting Systems,"We propose a method for simulating the stochastic dynamics of classical spin
+systems with long-range interactions. The method incorporates the stochastic
+cutoff (SCO) method, which is originally specialized for simulating equilibrium
+state, into time quantified Monte Carlo (TQMC) method. We analytically prove
+that the present method gives the same real-time dynamics with the stochastic
+Landau-Lifshitz-Gilbert (s-LLG) equation, i.e., both method derives the same
+Fokker-Planck coefficients. We demonstrate magnetization reversal processes and
+confirm that the result is in good agreement with the result obtained by s-LLG.
+Using our method enables us to analyze complicated lattice systems consisting
+of many spins in a unit cell. Technical improvement of TQMC is also proposed.",1811.00237v2
+2019-01-10,Multi-Parameter Regression Survival Modelling: An Alternative to Proportional Hazards,"It is standard practice for covariates to enter a parametric model through a
+single distributional parameter of interest, for example, the scale parameter
+in many standard survival models. Indeed, the well-known proportional hazards
+model is of this kind. In this paper we discuss a more general approach whereby
+covariates enter the model through more than one distributional parameter
+simultaneously (e.g., scale and shape parameters). We refer to this practice as
+""multi-parameter regression"" (MPR) modelling and explore its use in a survival
+analysis context. We find that multi-parameter regression leads to more
+flexible models which can offer greater insight into the underlying data
+generating process. To illustrate the concept, we consider the two-parameter
+Weibull model which leads to time-dependent hazard ratios, thus relaxing the
+typical proportional hazards assumption and motivating a new test of
+proportionality. A novel variable selection strategy is introduced for such
+multi-parameter regression models. It accounts for the correlation arising
+between the estimated regression coefficients in two or more linear predictors
+-- a feature which has not been considered by other authors in similar
+settings. The methods discussed have been implemented in the mpr package in R.",1901.03277v1
+2019-11-05,Numerical methods for antiferromagnetics,"Compared with ferromagnetic counterparts, antiferromagnetic materials are
+considered as the future of spintronic applications since these materials are
+robust against the magnetic perturbation, produce no stray field, and display
+ultrafast dynamics. There are (at least) two sets of magnetic moments in
+antiferromagnets (with magnetization of the same magnitude but antiparallel
+directions) and ferrimagnets (with magnetization of the different magnitude).
+The coupled dynamics for the bipartite collinear antiferromagnets is modeled by
+a coupled system of Landau-Lifshitz-Gilbert equations with an additional term
+originated from the antiferromagnetic exchange, which leads to femtosecond
+magnetization dynamics. In this paper, we develop three Gauss-Seidel projection
+methods for micromagnetics simulation in antiferromagnets and ferrimagnets.
+They are first-order accurate in time and second-order in space, and only solve
+linear systems of equations with constant coefficients at each step.
+Femtosecond dynamics, N\'{e}el wall structure, and phase transition in presence
+of an external magnetic field for antiferromagnets are provided with the
+femtosecond stepsize.",1911.01717v1
+2023-02-06,Landau theory for ferro-paramagnetic phase transition in finitely-strained viscoelastic magnets,"The thermodynamic model of visco-elastic deformable magnetic materials at
+finite strains is formulated in a fully Eulerian way in rates. The Landau
+theory applies for ferro-to-para-magnetic phase transition, the gradient theory
+(leading exchange energy) for magnetization with general mechanically dependent
+coefficient, hysteresis in magnetization evolution by Landau-Lifshitz-Gilbert
+equation involving objective corotational time derivative of magnetization, and
+demagnetizing field are considered in the model. The Kelvin-Voigt viscoelastic
+rheology with a higher-order viscosity (exploiting the concept of multipolar
+materials) is used, allowing for physically relevant frame-indifferent stored
+energies and for local invertibility of deformation. The model complies with
+energy conservation and Clausius-Duhem entropy inequality. Existence and a
+certain regularity of weak solutions is proved by a Faedo-Galerkin
+semi-discretization and a suitable regularization.",2302.02850v1
+2000-10-12,Friction in a solid lubricant film,"Molecular dynamics study of a thin (one to five layers) lubricant film
+between two substrates in moving contact are performed using Langevin equations
+with an external damping coefficient depending on distance and velocity of
+atoms relative the substrates, motivated by microscopic configurations. They
+show that the minimal friction coefficient is obtained for the solid-sliding
+regime. A detailed analysis of the results, the comparison with other
+microscopic modeling approaches of friction, and the evaluation of quantities
+that can be compared to experiments, such as the velocity of the transition
+from stick-slip to smooth sliding, are used to discuss the relevance of the
+microscopic simulations of friction.",0010185v1
+1993-06-01,Transport Properties of Solitons,"We calculate in this article the transport coefficients which characterize
+the dynamics of solitons in quantum field theory using the methods of
+dissipative quantum systems. We show how the damping and diffusion coefficients
+of soliton-like excitations can be calculated using the integral functional
+formalism. The model obtained in this article has new features which cannot be
+obtained in the standard models of dissipation in quantum mechanics.",9306007v1
+2008-10-01,Estimating Speed and Damping in the Stochastic Wave Equation,"A parameter estimation problem is considered for a one-dimensional stochastic
+wave equation driven by additive space-time Gaussian white noise.
+  The estimator is of spectral type and utilizes a finite number of the spatial
+Fourier coefficients of the solution. The asymptotic properties of the
+estimator are studied as the number of the Fourier coefficients increases,
+while the observation time and the noise intensity are fixed.",0810.0046v1
+2009-06-23,Parameter Estimation in Diagonalizable Stochastic Hyperbolic Equations,"A parameter estimation problem is considered for a linear stochastic
+hyperbolic equation driven by additive space-time Gaussian white noise. The
+damping/amplification operator is allowed to be unbounded.
+  The estimator is of spectral type and utilizes a finite number of the spatial
+Fourier coefficients of the solution. The asymptotic properties of the
+estimator are studied as the number of the Fourier coefficients increases,
+while the observation time and the noise intensity are fixed.",0906.4353v1
+2011-12-11,Shear viscosity and spin diffusion coefficient of a two-dimensional Fermi gas,"Using kinetic theory, we calculate the shear viscosity and the spin diffusion
+coefficient as well as the associated relaxation times for a two-component
+Fermi gas in two dimensions, as a function of temperature, coupling strength,
+polarization, and mass ratio of the two components. It is demonstrated that the
+minimum value of the viscosity decreases with the mass ratio, since Fermi
+blocking becomes less efficient. We furthermore analyze recent experimental
+results for the quadrupole mode of a 2D gas in terms of viscous damping
+obtaining a qualitative agreement using no fitting parameters.",1112.2395v2
+2014-03-12,Logarithmic stability in determining two coefficients in a dissipative wave equation. Extensions to clamped Euler-Bernoulli beam and heat equations,"We are concerned with the inverse problem of determining both the potential
+and the damping coefficient in a dissipative wave equation from boundary
+measurements. We establish stability estimates of logarithmic type when the
+measurements are given by the operator who maps the initial condition to
+Neumann boundary trace of the solution of the corresponding initial-boundary
+value problem. We build a method combining an observability inequality together
+with a spectral decomposition. We also apply this method to a clamped
+Euler-Bernoulli beam equation. Finally, we indicate how the present approach
+can be adapted to a heat equation.",1403.3018v2
+2015-03-16,Determining a boundary coefficient in a dissipative wave equation: Uniqueness and directional lipschitz stability,"We are concerned with the problem of determining the damping boundary
+coefficient appearing in a dissipative wave equation from a single boundary
+measurement. We prove that the uniqueness holds at the origin provided that the
+initial condition is appropriately chosen. We show that the choice of the
+initial condition leading to uniqueness is related to a fine version of unique
+continuation property for elliptic operators. We also establish a Lipschitz
+directional stability estimate at the origin, which is obtained by a
+linearization process.",1503.04528v1
+2015-04-28,Fractional relaxation and fractional oscillation models involving Erdelyi-Kober integrals,"We consider fractional relaxation and fractional oscillation equations
+involving Erdelyi-Kober integrals. In terms of Riemann-Liouville integrals, the
+equations we analyze can be understood as equations with time-varying
+coefficients. Replacing Riemann-Liouville integrals with Erdelyi-Kober-type
+integrals in certain fractional oscillation models, we obtain some more general
+integro-differential equations. The corresponding Cauchy-type problems can be
+solved numerically, and, in some cases analytically, in terms of Saigo-Kilbas
+Mittag-Leffler functions. The numerical results are obtained by a treatment
+similar to that developed by K. Diethelm and N.J. Ford to solve the
+Bagley-Torvik equation. Novel results about the numerical approach to the
+fractional damped oscillator equation with time-varying coefficients are also
+presented.",1504.07568v1
+2017-12-28,On well-posedness of Ericksen-Leslie's parabolic-hyperbolic liquid crystal model in compressible flow,"We study the Ericksen-Leslie's parabolic-hyperbolic liquid crystal model in
+compressible flow. Inspired by our study for incompressible case
+\cite{Jiang-Luo-arXiv-2017} and some techniques from compressible Navier-Stokes
+equations, we prove the local-in-time existence of the classical solution to
+the system with finite initial energy, under some constraints on the Leslie
+coefficients which ensure the basic energy law is dissipative. Furthermore,
+with an additional assumption on the coefficients which provides a damping
+effect, and the smallness of the initial energy, the global classical solution
+can be established.",1712.09799v1
+2018-02-02,Energy decay and global solutions for a damped free boundary fluid-elastic structure interface model with variable coefficients in elasticity,"We cope with a free boundary fluid-structure interaction model. In the model,
+the viscous incompressible fluid interacts with elastic body via the common
+boundary. The motion of the fluid is governed by Navier-Stokes equations while
+the displacement of elastic structure is described by variable coefficient wave
+equations. The dissipation is placed on the common boundary between fluid and
+elastic body. Given small initial data, the global existence of the solutions
+of this system is proved and the exponential decay of solutions are obtained.",1802.00585v2
+2020-05-23,Stability analysis of multi-term fractional-differential equations with three fractional derivatives,"Necessary and sufficient stability and instability conditions are obtained
+for multi-term homogeneous linear fractional differential equations with three
+Caputo derivatives and constant coefficients. In both cases,
+fractional-order-dependent as well as fractional-order-independent
+characterisations of stability and instability properties are obtained, in
+terms of the coefficients of the multi-term fractional differential equation.
+The theoretical results are exemplified for the particular cases of the Basset
+and Bagley-Torvik equations, as well as for a multi-term fractional
+differential equation of an inextensible pendulum with fractional damping
+terms, and for a fractional harmonic oscillator.",2005.11486v1
+2021-08-21,Heterogeneous multiscale methods for the Landau-Lifshitz equation,"In this paper, we present a finite difference heterogeneous multiscale method
+for the Landau-Lifshitz equation with a highly oscillatory diffusion
+coefficient. The approach combines a higher order discretization and artificial
+damping in the so-called micro problem to obtain an efficient implementation.
+The influence of different parameters on the resulting approximation error is
+discussed. Numerical examples for both periodic as well as more general
+coefficients are given to demonstrate the functionality of the approach.",2108.09463v1
+2022-04-22,Coefficient of restitution of a linear dashpot on a rigid surface,"The linear dashpot model is applied to a single ball bouncing on a rigid
+surface. It is shown that when gravity is included the coefficient of
+restitution depends on impact velocity, in contrast to previous work that
+ignored the effects of gravity. This velocity dependence is most pronounced at
+low impact velocities and high damping. Previous work has considered the ball
+to be in contact with the floor when the compression is nonzero, while other
+analysis terminates the collision earlier, to prevent an attractive force. We
+compare these models and propose a hybrid between the two. The hybrid model is
+successful in reproducing experimental results for a cart bouncing repeatedly
+on a spring.",2204.10917v1
+2023-05-05,When does an active bath behave as an equilibrium one?,"Active baths are characterized by a non-Gaussian velocity distribution and a
+quadratic dependence with active velocity $v_0$ of the kinetic temperature and
+diffusion coefficient. While these results hold in over-damped active systems,
+inertial effects lead to normal velocity distributions, with kinetic
+temperature and diffusion coefficient increasing as $\sim v_0^\alpha$ with
+$1<\alpha<2$. Remarkably, the late-time diffusivity and mobility decrease with
+mass. Moreover, we show that the equilibrium Einstein relation is
+asymptotically recovered with inertia. In summary, the inertial mass restores
+an equilibrium-like behavior.",2305.03830v1
+2023-08-09,Quantitative analysis of secondary Bjerkenes forces in various liquids,"Numerically calculating the interaction forces between two free bubbles under
+the action of a background of random acoustic radiation, we highlight the
+contributions of radiative coefficient and absorption damping coefficient to
+the size of these forces.It is quantitatively demonstrated, for different radii
+of the oscillating bubbles, that the scattering absorption forces and the
+scattering scattering forces are close in magnitude.For superfluid helium, the
+forces change direction, oscillatingly, and the ratio of the forces is much
+less than one.",2308.13530v1
+2010-11-29,Long-time dynamics of Kirchhoff wave models with strong nonlinear damping,"We study well-posedness and long-time dynamics of a class of quasilinear wave
+equations with a strong damping. We accept the Kirchhoff hypotheses and assume
+that the stiffness and damping coefficients are $C^1$ functions of the
+$L_2$-norm of the gradient of the displacement. We first prove the existence
+and uniqueness of weak solutions and study their properties for a rather wide
+class of nonlinearities which covers the case of possible degeneration (or even
+negativity) of the stiffness coefficient and the case of a supercritical source
+term. Our main results deal with global attractors. In the case of strictly
+positive stiffness factors we prove that in the natural energy space endowed
+with a partially strong topology there exists a global attractor whose fractal
+dimension is finite. In the non-supercritical case the partially strong
+topology becomes strong and a finite dimensional attractor exists in the strong
+topology of the energy space. Moreover, in this case we also establish the
+existence of a fractal exponential attractor and give conditions that guarantee
+the existence of a finite number of determining functionals. Our arguments
+involve a recently developed method based on ""compensated"" compactness and
+quasi-stability estimates.",1011.6271v3
+2013-09-13,Analytical and experimental stability investigation of a hardware-in-the-loop satellite docking simulator,"The European Proximity Operation Simulator (EPOS) of the DLR-German Aerospace
+Center is a robotics-based simulator that aims at validating and verifying a
+satellite docking phase. The generic concept features a robotics tracking
+system working in closed loop with a force/torque feedback signal. Inherent
+delays in the tracking system combined with typical high stiffness at contact
+challenge the stability of the closed-loop system. The proposed concept of
+operations is hybrid: the feedback signal is a superposition of a measured
+value and of a virtual value that can be tuned in order to guarantee a desired
+behavior. This paper is concerned with an analytical study of the system's
+closed-loop stability, and with an experimental validation of the hybrid
+concept of operations in one dimension (1D). The robotics simulator is modeled
+as a second-order loop-delay system and closed-form expressions for the
+critical delay and associated frequency are derived as a function of the
+satellites' mass and the contact dynamics stiffness and damping parameters. A
+numerical illustration sheds light on the impact of the parameters on the
+stability regions. A first-order Pade approximation provides additional means
+of stability investigation. Experiments were performed and tests results are
+described for varying values of the mass and the damping coefficients. The
+empirical determination of instability is based on the coefficient of
+restitution and on the observed energy. There is a very good agreement between
+the critical damping values predicted by the analysis and observed during the
+tests...",1309.3512v1
+2014-06-13,Magnetic-Field Amplification in the Thin X-ray Rims of SN1006,"Several young supernova remnants (SNRs), including SN1006, emit synchrotron
+X-rays in narrow filaments, hereafter thin rims, along their periphery. The
+widths of these rims imply 50 to 100 $\mu$G fields in the region immediately
+behind the shock, far larger than expected for the interstellar medium
+compressed by unmodified shocks, assuming electron radiative losses limit rim
+widths. However, magnetic-field damping could also produce thin rims. Here we
+review the literature on rim width calculations, summarizing the case for
+magnetic-field amplification. We extend these calculations to include an
+arbitrary power-law dependence of the diffusion coefficient on energy, $D
+\propto E^{\mu}$. Loss-limited rim widths should shrink with increasing photon
+energy, while magnetic-damping models predict widths almost independent of
+photon energy. We use these results to analyze Chandra observations of SN 1006,
+in particular the southwest limb. We parameterize the full widths at half
+maximum (FWHM) in terms of energy as FWHM $\propto E^{m_E}_{\gamma}$. Filament
+widths in SN1006 decrease with energy; $m_E \sim -0.3$ to $-0.8$, implying
+magnetic field amplification by factors of 10 to 50, above the factor of 4
+expected in strong unmodified shocks. For SN 1006, the rapid shrinkage rules
+out magnetic damping models. It also favors short mean free paths (small
+diffusion coefficients) and strong dependence of $D$ on energy ($\mu \ge 1$).",1406.3630v2
+2015-04-17,Effective Action for Cosmological Scalar Fields at Finite Temperature,"Scalar fields appear in many theories beyond the Standard Model of particle
+physics. In the early universe, they are exposed to extreme conditions,
+including high temperature and rapid cosmic expansion. Understanding their
+behavior in this environment is crucial to understand the implications for
+cosmology. We calculate the finite temperature effective action for the field
+expectation value in two particularly important cases, for damped oscillations
+near the ground state and for scalar fields with a flat potential. We find that
+the behavior in both cases can in good approximation be described by a complex
+valued effective potential that yields Markovian equations of motion. Near the
+potential minimum, we recover the solution to the well-known Langevin equation.
+For large field values we find a very different behavior, and our result for
+the damping coefficient differs from the expressions frequently used in the
+literature. We illustrate our results in a simple scalar model, for which we
+give analytic approximations for the effective potential and damping
+coefficient. We also provide various expressions for loop integrals at finite
+temperature that are useful for future calculations in other models.",1504.04444v2
+2017-05-19,Analytical Prediction of Reflection Coefficients for Wave Absorbing Layers in Flow Simulations of Regular Free-Surface Waves,"Undesired wave reflections, which occur at domain boundaries in flow
+simulations with free-surface waves, can be minimized by applying source terms
+in the vicinity of the boundary to damp the waves. Examples of such approaches
+are absorbing layers, damping zones, forcing zones, relaxation zones and sponge
+layers. A problem with these approaches is that the effectivity of the wave
+damping depends on the parameters in the source term functions, which are
+case-dependent and must be adjusted to the wave. The present paper presents a
+theory which analytically predicts the reflection coefficients and which can be
+used to optimally select the source term parameters before running the
+simulation. The theory is given in a general form so that it is applicable to
+many existing implementations. It is validated against results from
+finite-volume-based flow simulations of regular free-surface waves and found to
+be of satisfactory accuracy for practical purposes.",1705.06940v2
+2018-07-26,Aspherical deformations of the Choptuik spacetime,"We perform dynamical and nonlinear numerical simulations to study critical
+phenomena in the gravitational collapse of massless scalar fields in the
+absence of spherical symmetry. We evolve axisymmetric sets of initial data and
+examine the effects of deviation from spherical symmetry. For small deviations
+we find values for the critical exponent and echoing period of the discretely
+self-similar critical solution that agree well with established values;
+moreover we find that such small deformations behave like damped oscillations
+whose damping coefficient and oscillation frequencies are consistent with those
+predicted in the linear perturbation calculations of Martin-Garcia and
+Gundlach. However, we also find that the critical exponent and echoing period
+appear to decrease with increasing departure from sphericity, and that, for
+sufficiently large departures from spherical symmetry, the deviations become
+unstable and grow, confirming earlier results by Choptuik et.al.. We find some
+evidence that these growing modes lead to a bifurcation, similar to those
+reported by Choptuik et.al., with two centers of collapse forming on the
+symmetry axis above and below the origin. These findings suggest that nonlinear
+perturbations of the critical solution lead to changes in the effective values
+of the critical exponent, echoing period and damping coefficient, and may even
+change the sign of the latter, so that perturbations that are stable in the
+linear regime can become unstable in the nonlinear regime.",1807.10342v2
+2019-03-07,Non-linear diffusion of cosmic rays escaping from supernova remnants - II. Hot ionized media,"We study the problem of the escape and transport of Cosmic-Rays (CR) from a
+source embedded in a fully ionised, hot phase of the interstellar medium (HIM).
+In particular, we model the CR escape and their propagation in the source
+vicinity taking into account excitation of Alfv\'enic turbulence by CR
+streaming and mechanisms damping the self-excited turbulence itself. Our
+estimates of escape radii and times result in large values (100 pc,
+$2\times10^5$ yr) for particle energies $\lesssim20$ GeV and smaller values for
+particles with increasing energies (35 pc and 14 kyr at 1 TeV). These escape
+times and radii, when used as initial conditions for the CR propagation outside
+the source, result in relevant suppression of the diffusion coefficient (by a
+factor 5-10) on time-scales comparable with their (energy dependent) escape
+time-scale. The damping mechanisms are fast enough that even on shorter time
+scales the Alfv\'enic turbulence is efficiently damped, and the ratio between
+random and ordered component of the magnetic field is $\delta B/B_0\ll 1$,
+justifying the use of quasi-linear theory. In spite of the suppressed diffusion
+coefficient, and then the increased residence time in the vicinity (<200 pc) of
+their source, the grammage accumulated by CRs after their escape is found to be
+negligible (at all energies) as compared to the one accumulated while diffusing
+in the whole Galaxy, due to the low density of the HIM.",1903.03193v1
+1997-09-04,Cosmic-Ray Momentum Diffusion In Magnetosonic Versus Alfvenic Turbulent Field,"Energetic particle transport in a finite amplitude magnetosonic and Alfvenic
+turbulence is considered using Monte Carlo particle simulations, which involve
+an integration of particle equation of motion. We show that in a low-Betha
+plasma cosmic ray can be the most important damping process for magnetosonic
+waves. Assuming such conditions we derive the momentum diffusion coefficient
+for relativistic particles in the presence of anisotropic finite-amplitude
+turbulent wave field, for flat and Kolmogorov-type turbulence spectra. We
+confirm the possibility of larger values of a momentum diffusion coefficient
+occuring due to transit-time damping resonance interaction in the presence of
+isotropic fast-mode waves in comparison to the Alfven waves of the same
+amplitude.",9709039v2
+2003-05-01,Scalar perturbation spectra from warm inflation,"We present a numerical integration of the cosmological scalar perturbation
+equations in warm inflation. The initial conditions are provided by a
+discussion of the thermal fluctuations of an inflaton field and thermal
+radiation using a combination of thermal field theory and thermodynamics. The
+perturbation equations include the effects of a damping coefficient $\Gamma$
+and a thermodynamic potential $V$. We give an analytic expression for the
+spectral index of scalar fluctuations in terms of a new slow-roll parameter
+constructed from $\Gamma$. A series of toy models, inspired by spontaneous
+symmetry breaking and a known form of the damping coefficient, lead to a
+spectrum with $n_s>1$ on large scales and $n_s<1$ on small scales.",0305015v3
+2000-09-21,Landau-Khalatnikov two-fluid hydrodynamics of a trapped Bose gas,"Starting from the quantum kinetic equation for the non-condensate atoms and
+the generalized Gross-Pitaevskii equation for the condensate, we derive the
+two-fluid hydrodynamic equations of a trapped Bose gas at finite temperatures.
+We follow the standard Chapman-Enskog procedure, starting from a solution of
+the kinetic equation corresponding to the complete local equilibrium between
+the condensate and the non-condensate components. Our hydrodynamic equations
+are shown to reduce to a form identical to the well-known Landau-Khalatnikov
+two-fluid equations, with hydrodynamic damping due to the deviation from local
+equilibrium. The deviation from local equilibrium within the thermal cloud
+gives rise to dissipation associated with shear viscosity and thermal
+conduction. In addition, we show that effects due to the deviation from the
+diffusive local equilibrium between the condensate and the non-condensate
+(recently considered by Zaremba, Nikuni and Griffin) can be described by four
+frequency-dependent second viscosity transport coefficients. We also derive
+explicit formulas for all the transport coefficients. These results are used to
+introduce two new characteristic relaxation times associated with hydrodynamic
+damping. These relaxation times give the rate at which local equilibrium is
+reached and hence determine whether one is in the two-fluid hydrodynamic
+region.",0009333v1
+1999-05-28,Existence threshold for the ac-driven damped nonlinear Schrödinger solitons,"It has been known for some time that solitons of the externally driven,
+damped nonlinear Schr\""odinger equation can only exist if the driver's
+strength, $h$, exceeds approximately $(2/ \pi) \gamma$, where $\gamma$ is the
+dissipation coefficient. Although this perturbative result was expected to be
+correct only to the leading order in $\gamma$, recent studies have demonstrated
+that the formula $h_{thr}= (2 /\pi) \gamma$ gives a remarkably accurate
+description of the soliton's existence threshold prompting suggestions that it
+is, in fact, exact. In this note we evaluate the next order in the expansion of
+$h_{thr}(\gamma)$ showing that the actual reason for this phenomenon is simply
+that the next-order coefficient is anomalously small: $h_{thr}=(2/ \pi) \gamma
++ 0.002 \gamma^3$. Our approach is based on a singular perturbation expansion
+of the soliton near the turning point; it allows to evaluate $h_{thr}(\gamma)$
+to all orders in $\gamma$ and can be easily reformulated for other perturbed
+soliton equations.",9906001v1
+2009-11-11,Ginzburg-Landau equation for dynamical four-wave mixing in gain nonlinear media with relaxation,"We consider the dynamical degenerate four-wave mixing (FWM) model in a cubic
+nonlinear medium including both the time relaxation of the induced nonlinearity
+and the nonlocal coupling. The initial ten-dimensional FWM system can be
+rewritten as a three-variable intrinsic system (namely the intensity pattern,
+the amplitude of the nonlinearity and the total net gain) which is very close
+to the pumped Maxwell-Bloch system. In the case of a purely nonlocal response
+the initial system reduces to a real damped sine-Gordon (SG) equation. We
+obtain a new solution of this equation in the form of a sech function with a
+time-dependent coefficient. By applying the reductive perturbation method to
+this damped SG equation, we obtain exactly the cubic complex Ginzburg Landau
+equation (CGL3), but with a time dependence in the loss/gain coefficient. The
+CGL3 describes the properties of the spatially localized interference pattern
+formed by the FWM.",0911.2129v1
+2010-02-05,Damped-driven KdV and effective equation for long-time behaviour of its solutions,"For the damped-driven KdV equation $$ \dot
+u-\nu{u_{xx}}+u_{xxx}-6uu_x=\sqrt\nu \eta(t,x), x\in S^1, \int u dx\equiv
+\int\eta dx\equiv0, $$ with $0<\nu\le1$ and smooth in $x$ white in $t$ random
+force $\eta$, we study the limiting long-time behaviour of the KdV integrals of
+motions $(I_1,I_2,...)$, evaluated along a solution $u^\nu(t,x)$, as $\nu\to0$.
+We prove that %if $u=u^\nu(t,x)$ is a solution of the equation above, for
+$0\le\tau:= \nu t \lesssim1$ the vector $
+I^\nu(\tau)=(I_1(u^\nu(\tau,\cdot)),I_2(u^\nu(\tau,\cdot)),...), $ converges in
+distribution to a limiting process $I^0(\tau)=(I^0_1,I^0_2,...)$. The $j$-th
+component $I_j^0$ equals $\12(v_j(\tau)^2+v_{-j}(\tau)^2)$, where
+$v(\tau)=(v_1(\tau), v_{-1}(\tau),v_2(\tau),...)$ is the vector of Fourier
+coefficients of a solution of an {\it effective equation} for the
+dam-ped-driven KdV. This new equation is a quasilinear stochastic heat equation
+with a non-local nonlinearity, written in the Fourier coefficients. It is well
+posed.",1002.1294v1
+2011-07-13,q-damped Oscillator and degenerate roots of constant coefficients q-difference ODE,"The classical model of q-damped oscillator is introduced and solved in terms
+of Jackson q-exponential function for three different cases, under-damped,
+over-damped and the critical one. It is shown that in all three cases solution
+is oscillating in time but is unbounded and non-periodic. By q-periodic
+function modulation, the self-similar micro-structure of the solution for small
+time intervals is derived. In the critical case with degenerate roots, the
+second linearly independent solution is obtained as a limiting case of two
+infinitesimally close roots. It appears as standard derivative of q-exponential
+and is rewritten in terms of the q-logarithmic function. We extend our result
+by constructing n linearly independent set of solutions to a generic constant
+coefficient q-difference equation degree N with n degenerate roots.",1107.2518v1
+2011-12-21,A numerical method for computing radially symmetric solutions of a dissipative nonlinear modified Klein-Gordon equation,"In this paper we develop a finite-difference scheme to approximate radially
+symmetric solutions of the initial-value problem with smooth initial conditions
+in an open sphere around the origin, where the internal and external damping
+coefficients are constant, and the nonlinear term follows a power law. We prove
+that our scheme is consistent of second order when the nonlinearity is
+identically equal to zero, and provide a necessary condition for it to be
+stable order n. Part of our study will be devoted to compare the physical
+effects of the damping coefficients.",1112.4921v1
+2013-08-20,Group classification and exact solutions of variable-coefficient generalized Burgers equations with linear damping,"Admissible point transformations between Burgers equations with linear
+damping and time-dependent coefficients are described and used in order to
+exhaustively classify Lie symmetries of these equations. Optimal systems of
+one- and two-dimensional subalgebras of the Lie invariance algebras obtained
+are constructed. The corresponding Lie reductions to ODEs and to algebraic
+equations are carried out. Exact solutions to particular equations are found.
+Some generalized Burgers equations are linearized to the heat equation by
+composing equivalence transformations with the Hopf-Cole transformation.",1308.4265v2
+2015-05-21,Control and stabilization of degenerate wave equations,"We study a wave equation in one space dimension with a general diffusion
+coefficient which degenerates on part of the boundary. Degeneracy is measured
+by a real parameter $\mu_a>0$. We establish observability inequalities for
+weakly (when $\mu_a \in [0,1[$) as well as strongly (when $\mu_a \in [1,2[$)
+degenerate equations. We also prove a negative result when the diffusion
+coefficient degenerates too violently (i.e. when $\mu_a>2$) and the blow-up of
+the observability time when $\mu_a$ converges to $2$ from below. Thus, using
+the HUM method we deduce the exact controllability of the corresponding
+degenerate control problem when $\mu_a \in [0,2[$. We conclude the paper by
+studying the boundary stabilization of the degenerate linearly damped wave
+equation and show that a suitable boundary feedback stabilizes the system
+exponentially. We extend this stability analysis to the degenerate nonlinearly
+boundary damped wave equation, for an arbitrarily growing nonlinear feedback
+close to the origin. This analysis proves that the degeneracy does not affect
+the optimal energy decay rates at large time. We apply the optimal-weight
+convexity method of \cite{alaamo2005, alajde2010} together with the results of
+the previous section, to perform this stability analysis.",1505.05720v1
+2020-04-14,Stability results of an elastic/viscoelastic transmission problem of locally coupled waves with non smooth coefficients,"We investigate the stabilization of a locally coupled wave equations with
+only one internal viscoelastic damping of Kelvin-Voigt type. The main novelty
+in this paper is that both the damping and the coupling coefficients are non
+smooth. First, using a general criteria of Arendt-Batty, combined with an
+uniqueness result, we prove that our system is strongly stable. Next, using a
+spectrum approach, we prove the non-exponential (uniform) stability of the
+system. Finally, using a frequency domain approach, combined with a piecewise
+multiplier technique and the construction of a new multiplier satisfying some
+ordinary differential equations, we show that the energy of smooth solutions of
+the system decays polynomially of type t^{-1}.",2004.06758v1
+2020-12-23,The fate of nonlinear perturbations near the QCD critical point,"The impact of the QCD critical point on the propagation of nonlinear waves
+has been studied. The effects have been investigated within the scope of
+second-order causal dissipative hydrodynamics by incorporating the critical
+point into the equation of state, and the scaling behaviour of transport
+coefficients and of thermodynamic response functions. Near the critical point,
+the nonlinear waves are found to be significantly damped which may result in
+the disappearance of the Mach cone effects of the away side jet. Such damping
+may lead to enhancement in the fluctuations of elliptic and higher flow
+coefficients. Therefore, the disappearance of Mach cone effects and the
+enhancement of fluctuations in flow harmonics in the event-by-event analysis
+may be considered as signals of the critical endpoint.",2012.12668v3
+2021-01-29,Quarter and Full Car Models Optimisation of Passive and Active Suspension System Using Genetic Algorithm,"This study evaluates a suspension design of a passenger car to obtain maximum
+rider's comfort when the vehicle is subjected to different road profile or road
+surface condition. The challenge will be on finding a balance between the
+rider's comfort and vehicle handling to optimize design parameters. The study
+uses a simple passive suspension system and an active suspension model
+integrated with a pneumatic actuator controlled by proportional integral
+derivative (PID) controller in both quarter car and full car models having a
+different degree of freedoms (DOF) and increasing degrees of complexities. The
+quarter car considered as a 2-DOF model, while the full car model is a 7-DOF
+model. The design process set to optimise the spring stiffnesses, damping
+coefficients and actuator PID controller gains. For optimisation, the research
+featured genetic algorithm optimisation technique to obtain a balanced response
+of the vehicle as evaluated from the displacement, velocity and acceleration of
+sprung and unsprung masses along with different human comfort and vehicle
+performance criteria. The results revealed that the active suspension system
+with optimised spring stiffness, damping coefficients and PID gains
+demonstrated the superior riding comfort and road holding compared to a passive
+suspension system.",2101.12629v1
+2021-03-06,Deep learning stochastic processes with QCD phase transition,"It is non-trivial to recognize phase transitions and track dynamics inside a
+stochastic process because of its intrinsic stochasticity. In this paper, we
+employ the deep learning method to classify the phase orders and predict the
+damping coefficient of fluctuating systems under Langevin's description. As a
+concrete set-up, we demonstrate this paradigm for the scalar condensation in
+QCD matter near the critical point, in which the order parameter of chiral
+phase transition can be characterized in a $1+1$-dimensional Langevin equation
+for $\sigma$ field. In a supervised learning manner, the Convolutional Neural
+Networks(CNNs) accurately classify the first-order phase transition and
+crossover based on $\sigma$ field configurations with fluctuations. Noise in
+the stochastic process does not significantly hinder the performance of the
+well-trained neural network for phase order recognition. For mixed dynamics
+with diverse dynamical parameters, we further devise and train the machine to
+predict the damping coefficients $\eta$ in a broad range. The results show that
+it is robust to extract the dynamics from the bumpy field configurations.",2103.04090v1
+2022-05-23,"Global existence, uniqueness and $L^{\infty}$-bound of weak solutions of fractional time-space Keller-Segel system","This paper studies the properties of weak solutions to a class of space-time
+fractional parabolic-elliptic Keller-Segel equations with logistic source terms
+in $\mathbb{R}^{n}$, $n\geq 2$. The global existence and $L^{\infty}$-bound of
+weak solutions are established. We mainly divide the damping coefficient into
+two cases: (i) $b>1-\frac{\alpha}{n}$, for any initial value and birth rate;
+(ii) $0<b\leq 1-\frac{\alpha}{n}$, for small initial value and small birth
+rate. The existence result is obtained by verifying the existence of a solution
+to the constructed regularization equation and incorporate the generalized
+compactness criterion of time fractional partial differential equation. At the
+same time, we get the $L^{\infty}$-bound of weak solutions by establishing the
+fractional differential inequality and using the Moser iterative method.
+Furthermore, we prove the uniqueness of weak solutions by using the
+hyper-contractive estimates when the damping coefficient is strong. Finally, we
+also propose a blow-up criterion for weak solutions, that is, if a weak
+solution blows up in finite time, then for all $h>q$, the $L^{h}$-norms of the
+weak solution blow up at the same time.",2205.11041v1
+2023-03-30,Superfluid $^3$He-B Surface States in a Confined Geometry Probed by a Microelectromechanical Oscillator,"A microelectromechanical oscillator with a 0.73 $\mu$m gap structure is
+employed to probe the surface Andreev bound states in superfluid $^3$He-B. The
+surface specularity of the oscillator is increased by preplating it with 1.6
+monolayers of $^4$He. In the linear regime, the temperature dependence of the
+damping coefficient is measured at various pressures, and the normalized energy
+gap is extracted. The damping coefficient increases after preplating at lower
+pressures, which is attributed to the decreased energy minigap of the surface
+bound states. The device is also driven into the nonlinear regime, where the
+temperature independent critical velocity at each pressure is measured. The
+critical velocity is observed to increase after preplating at all pressures,
+which might be related to the increased average energy gap. The observed
+behavior warrants a microscopic theory beyond a single parameter
+characterization of the surface.",2303.17073v1
+2023-06-10,"Discrepant Approaches to Modeling Stellar Tides, and the Blurring of Pseudosynchronization","We examine the reasons for discrepancies between two alternative approaches
+to modeling small-amplitude tides in binary systems. The 'direct solution' (DS)
+approach solves the governing differential equations and boundary conditions
+directly, while the 'modal decomposition' (MD) approach relies on a normal-mode
+expansion. Applied to a model for the primary star in the heartbeat system
+KOI-54, the two approaches predict quite different behavior of the secular
+tidal torque. The MD approach exhibits the pseudosynchronization phenomenon,
+where the torque due to the equilibrium tide changes sign at a single,
+well-defined and theoretically predicted stellar rotation rate. The DS approach
+instead shows 'blurred' pseudosynchronization, where positive and negative
+torques intermingle over a range of rotation rates.
+  We trace a major source of these differences to an incorrect damping
+coefficient in the profile functions describing the frequency dependence of the
+MD expansion coefficients. With this error corrected some differences between
+the approaches remain; however, both are in agreement that
+pseudosynchronization is blurred in the KOI-54 system. Our findings generalize
+to any type of star for which the tidal damping depends explicitly or
+implicitly on the forcing frequency.",2306.06429v1
+2023-08-25,The time dimensional reduction method to determine the initial conditions without the knowledge of damping coefficients,"This paper aims to reconstruct the initial condition of a hyperbolic equation
+with an unknown damping coefficient. Our approach involves approximating the
+hyperbolic equation's solution by its truncated Fourier expansion in the time
+domain and using a polynomial-exponential basis. This truncation process
+facilitates the elimination of the time variable, consequently, yielding a
+system of quasi-linear elliptic equations. To globally solve the system without
+needing an accurate initial guess, we employ the Carleman contraction
+principle. We provide several numerical examples to illustrate the efficacy of
+our method. The method not only delivers precise solutions but also showcases
+remarkable computational efficiency.",2308.13152v1
+2024-02-05,Symmetries and conservation laws of a fifth-order KdV equation with time-dependent coefficients and linear damping,"A fifth-order KdV equation with time dependent coefficients and linear
+damping has been studied. Symmetry groups have several different applications
+in the context of nonlinear differential equations. For instance, they can be
+used to determine conservation laws. We obtain the symmetries of the model
+applying Lie's classical method. The choice of some arbitrary functions of the
+equation by the equivalence transformation enhances the study of Lie symmetries
+of the equation. We have determined the subclasses of the equation which are
+nonlinearly self-adjoint. This allow us to obtain conservation laws by using a
+theorem proved by Ibragimov which is based on the concept of adjoint equation
+for nonlinear differential equations.",2402.03265v1
+2022-10-11,Finite-time singularity formations for the Landau-Lifshitz-Gilbert equation in dimension two,"We construct finite time blow-up solutions to the Landau-Lifshitz-Gilbert
+equation (LLG) from ${\mathbb R}^2$ into $S^2$ \begin{equation*} \begin{cases}
+u_t= a(\Delta u+|\nabla u|^2u) -b u\wedge \Delta u &\ \mbox{ in }\ {\mathbb
+R}^2\times(0,T), u(\cdot,0) = u_0\in S^2 &\ \mbox{ in }\ {\mathbb R}^2,
+\end{cases} \end{equation*} where $a^2+b^2=1,~a > 0,~ b\in {\mathbb R}$. Given
+any prescribed $N$ points in $\mathbb{R}^2$ and small $T>0$, we prove that
+there exists regular initial data such that the solution blows up precisely at
+these points at finite time $t=T$, taking around each point the profile of
+sharply scaled degree 1 harmonic map with the type II blow-up speed
+\begin{equation*} \| \nabla u\|_{L^\infty } \sim \frac{|\ln(T-t)|^2}{ T-t } \
+\mbox{ as } \ t\to T. \end{equation*} The proof is based on the {\em parabolic
+inner-outer gluing method}, developed in \cite{17HMF} for Harmonic Map Flow
+(HMF). However, a direct consequence of the presence of dispersion is the {\em
+lack of maximum principle} for suitable quantities, which makes the analysis
+more delicate even at the linearized level. To overcome this difficulty, we
+make use of two key technical ingredients: first, for the inner problem we
+employ the tool of {\em distorted Fourier transform}, as developed by Krieger,
+Miao, Schlag and Tataru \cite{Krieger09Duke,KMS20WM}. Second, the linear theory
+for the outer problem is achieved by means of the sub-Gaussian estimate for the
+fundamental solution of parabolic system in non-divergence form with
+coefficients of Dini mean oscillation in space ($\mathsf{DMO_x}$), which was
+proved by Dong, Kim and Lee \cite{dong22-non-divergence} recently.",2210.05800v1
+2023-03-07,Multilevel Monte Carlo methods for stochastic convection-diffusion eigenvalue problems,"We develop new multilevel Monte Carlo (MLMC) methods to estimate the
+expectation of the smallest eigenvalue of a stochastic convection-diffusion
+operator with random coefficients. The MLMC method is based on a sequence of
+finite element (FE) discretizations of the eigenvalue problem on a hierarchy of
+increasingly finer meshes. For the discretized, algebraic eigenproblems we use
+both the Rayleigh quotient (RQ) iteration and implicitly restarted Arnoldi
+(IRA), providing an analysis of the cost in each case. By studying the variance
+on each level and adapting classical FE error bounds to the stochastic setting,
+we are able to bound the total error of our MLMC estimator and provide a
+complexity analysis. As expected, the complexity bound for our MLMC estimator
+is superior to plain Monte Carlo. To improve the efficiency of the MLMC
+further, we exploit the hierarchy of meshes and use coarser approximations as
+starting values for the eigensolvers on finer ones. To improve the stability of
+the MLMC method for convection-dominated problems, we employ two additional
+strategies. First, we consider the streamline upwind Petrov--Galerkin
+formulation of the discrete eigenvalue problem, which allows us to start the
+MLMC method on coarser meshes than is possible with standard FEs. Second, we
+apply a homotopy method to add stability to the eigensolver for each sample.
+Finally, we present a multilevel quasi-Monte Carlo method that replaces Monte
+Carlo with a quasi-Monte Carlo (QMC) rule on each level. Due to the faster
+convergence of QMC, this improves the overall complexity. We provide detailed
+numerical results comparing our different strategies to demonstrate the
+practical feasibility of the MLMC method in different use cases. The results
+support our complexity analysis and further demonstrate the superiority over
+plain Monte Carlo in all cases.",2303.03673v2
+2008-12-31,Weak Solutions of the Stochastic Landau-Lifshitz-Gilbert Equation,"The Landau-Lifshitz-Gilbert equation perturbed by a multiplicative
+space-dependent noise is considered for a ferromagnet filling a bounded
+three-dimensional domain. We show the existence of weak martingale solutions
+taking values in a sphere $\mathbb S^2$. The regularity of weak solutions is
+also discussed. Some of the regularity results are new even for the
+deterministic Landau-Lifshitz-Gilbert equation.",0901.0039v1
+2023-09-08,Branching points in the planar Gilbert--Steiner problem have degree 3,"Gilbert--Steiner problem is a generalization of the Steiner tree problem on a
+specific optimal mass transportation.
+  We show that every branching point in a solution of the planar
+Gilbert--Steiner problem has degree 3.",2309.04202v2
+2000-03-27,Electron-Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements IV. Relativistic calculations for C IV and C V for UV and X-ray modeling,"The first complete set of unified cross sections and rate coefficients are
+calculated for photoionization and recombination of He- and Li-like ions using
+the relativistic Breit-Pauli R-matrix method. We present total, unified (e +
+ion) recombination rate coefficients for (e + C VI ---> C V) and (e + C V
+\longrightarrow C IV) including fine structure. Level-specific recombination
+rate coefficients up to the n = 10 levels are also obtained for the first time;
+these differ considerably from the approximate rates currently available.
+Applications to recombination-cascade coefficients in X-ray spectral models of
+K-alpha emission from the important He-like ions is pointed out. The overall
+uncertainty in the total recombination rates should not exceed 10-20%.
+Ionization fractions for Carbon are recomputed in the coronal approximation
+using the new rates.
+  The present (e + ion) recombination rate coefficients are compared with
+several sets of available data, including previous LS coupling results, and
+`experimentally derived' rate coefficients. The role of relativistic fine
+structure, resolution of resonances, radiation damping, and interference
+effects is discussed. Two general features of recombination rates are noted:
+(i) the non-resonant (radiative recombination) peak as E,T ---> 0, and the (ii)
+the high-T resonant (di-electronic recombination) peak.",0003411v2
+2018-07-19,Magnetization nutation induced by surface effects in nanomagnets,"We investigate the magnetization dynamics of ferromagnetic nanoparticles in
+the atomistic approach taking account of surface anisotropy and the spin
+misalignment it causes. We demonstrate that such inhomogeneous spin
+configurations induce nutation in the dynamics of the particle's magnetization.
+More precisely, in addition to the ordinary precessional motion with frequency
+$f_{p}\sim10\,{\rm GHz}$, we find that the dynamics of the net magnetic moment
+exhibits two more resonance peaks with frequencies $f_{c}$ and $f_{n}$ which
+are higher than the frequency $f_{p} : f_{c}=4\times f_{p}\sim40\,{\rm GHz}$ is
+related with the oscillations of the particle's magnetic moment between the
+minima of the effective potential induced by weak surface anisotropy. On the
+other hand, the much higher frequency $f_{n}\sim1\,{\rm THz}$ is attributed to
+the magnetization fluctuations at the atomic level driven by exchange
+interaction. We have compared our results on nutation induced by surface
+effects with those rendered by the macroscopic approach based on the
+Landau-Lifshitz-Gilbert equation augmented by an inertial term (proportional to
+the second-order time derivative of the macroscopic moment) with a
+phenomenological coefficient. The good agreement between the two models have
+allowed us to estimate the latter coefficient in terms of the atomistic
+parameters such as the surface anisotropy constant. We have thus proposed a new
+origin for the magnetization nutations as being induced by surface effects and
+have interpreted the corresponding resonance peaks and their frequencies.",1807.07392v1
+2021-07-02,Scaling of Turbulent Viscosity and Resistivity: Extracting a Scale-dependent Turbulent Magnetic Prandtl Number,"Turbulent viscosity $\nu_t$ and resistivity $\eta_t$ are perhaps the simplest
+models for turbulent transport of angular momentum and magnetic fields,
+respectively. The associated turbulent magnetic Prandtl number $Pr_t\equiv
+\nu_t/\eta_t$ has been well recognized to determine the final magnetic
+configuration of accretion disks. Here, we present an approach to determining
+these ''effective transport'' coefficients acting at different length-scales
+using coarse-graining and recent results on decoupled kinetic and magnetic
+energy cascades [Bian & Aluie 2019]. By analyzing the kinetic and magnetic
+energy cascades from a suite of high-resolution simulations, we show that our
+definitions of $\nu_t$, $\eta_t$, and $Pr_t$ have power-law scalings in the
+''decoupled range.'' We observe that $Pr_t\approx1 \text{~to~}2$ at the
+smallest inertial-inductive scales, increasing to $\approx 5$ at the largest
+scales. However, based on physical considerations, our analysis suggests that
+$Pr_t$ has to become scale-independent and of order unity in the decoupled
+range at sufficiently high Reynolds numbers (or grid-resolution), and that the
+power-law scaling exponents of velocity and magnetic spectra become equal. In
+addition to implications to astrophysical systems, the scale-dependent
+turbulent transport coefficients offer a guide for large eddy simulation
+modeling.",2107.00861v1
+2023-01-23,Correction of high-order phase variation effects in dynamic field monitoring,"Purpose: Field monitoring measures field perturbations, which can be
+accounted for during image reconstructions. In certain field monitoring
+environments, significant phase deviations can arise far from isocenter due to
+the finite extent of the gradient and/or main magnet. This can degrade the
+accuracy of field dynamics when field probes are placed near or outside the
+diameter spherical volume of the gradient coils and/or main magnet, leading to
+corrupted image quality. The objective of this work was to develop a correction
+algorithm that reduces errors from highly nonlinear phase variations at distant
+field probes in field dynamic fits. Methods: The algorithm is split into three
+components. Component one fits phase coefficients one spatial order at a time,
+while the second implements a weighted least squares solution based on probe
+distance. After initial fitting, component three calculates phase residuals and
+removes the phase for distant probes before re-fitting. Two healthy volunteers
+were scanned on a head-only 7T MRI using diffusion-weighted single-shot spiral
+and EPI sequences and field monitoring was performed. Images were reconstructed
+with and without phase coefficient correction and compared qualitatively.
+Results: The algorithm was able to correct corrupted field dynamics, resulting
+in image quality improvements. Significant artefact reduction was observed when
+correcting higher order fits, especially for diffusion weighted images.
+Stepwise fitting provided the most correction benefit, which was marginally
+improved when adding weighted least squares and phase residual corrections.
+Conclusion: The proposed algorithm can mitigate effects of phase errors in
+field monitoring, providing improved reliability of field dynamic
+characterization.",2301.09726v1
+2003-03-17,Quantum phase space function formulation of reactive flux theory,"On the basis of a coherent state representation of quantum noise operator and
+an ensemble averaging procedure a scheme for quantum Brownian motion has been
+proposed recently [Banerjee {\it et al}, Phys. Rev. E {\bf65}, 021109 (2002);
+{\bf66}, 051105 (2002)]. We extend this approach to formulate reactive flux
+theory in terms of quantum phase space distribution functions and to derive a
+time dependent quantum transmission coefficient - a quantum analogue of
+classical Kramers'-Grote-Hynes coefficient in the spirit of Kohen and Tannor's
+classical formulation. The theory is valid for arbitrary noise correlation and
+temperature. The specific forms of this coefficient in the Markovian as well as
+in the non-Markovian limits have been worked out in detail for intermediate to
+strong damping regime with an analysis of quantum effects. While the classical
+transmission coefficient is independent of temperature, its quantum counterpart
+has significant temperature dependence particularly in the low temperature
+regime.",0303319v1
+2017-01-30,Regularized solutions for some backward nonlinear parabolic equations with statistical data,"In this paper, we study the backward problem of determining initial condition
+for some class of nonlinear parabolic equations in multidimensional domain
+where data are given under random noise. This problem is ill-posed, i.e., the
+solution does not depend continuously on the data. To regularize the instable
+solution, we develop some new methods to construct some new regularized
+solution. We also investigate the convergence rate between the regularized
+solution and the solution of our equations. In particular, we establish results
+for several equations with constant coefficients and time dependent
+coefficients. The equations with constant coefficients include heat equation,
+extended Fisher-Kolmogorov equation, Swift-Hohenberg equation and many others.
+The equations with time dependent coefficients include Fisher type Logistic
+equations, Huxley equation, Fitzhugh-Nagumo equation. The methods developed in
+this paper can also be applied to get approximate solutions to several other
+equations including 1-D Kuramoto-Sivashinsky equation, 1-D modified
+Swift-Hohenberg equation, strongly damped wave equation and 1-D Burger's
+equation with randomly perturbed operator.",1701.08459v2
+2019-04-18,Random coefficient autoregressive processes describe Brownian yet non-Gaussian diffusion in heterogeneous systems,"Many studies on biological and soft matter systems report the joint presence
+of a linear mean-squared displacement and a non-Gaussian probability density
+exhibiting, for instance, exponential or stretched-Gaussian tails. This
+phenomenon is ascribed to the heterogeneity of the medium and is captured by
+random parameter models such as ""superstatistics"" or ""diffusing diffusivity"".
+Independently, scientists working in the area of time series analysis and
+statistics have studied a class of discrete-time processes with similar
+properties, namely, random coefficient autoregressive models. In this work we
+try to reconcile these two approaches and thus provide a bridge between
+physical stochastic processes and autoregressive models. We start from the
+basic Langevin equation of motion with time-varying damping or diffusion
+coefficients and establish the link to random coefficient autoregressive
+processes. By exploring that link we gain access to efficient statistical
+methods which can help to identify data exhibiting Brownian yet non-Gaussian
+diffusion.",1904.08737v2
+2023-05-10,Poles of hydrodynamic spectral functions and Einstein-Helfand formulas for transport coefficients,"The local-equilibrium approach to transport processes is related to the
+approach based on time-dependent correlation functions and their associated
+spectral functions characterizing the equilibrium fluctuations of particle,
+momentum and other densities. On the one hand, the transport coefficients are
+calculated with the Einstein-Helfand formulas derived in the local-equilibrium
+approach. On the other hand, the poles of the spectral functions at complex
+frequencies give the damping rates of the hydrodynamic modes. Since these rates
+also depend on the transport coefficients, their values can be compared to the
+predictions of the local-equilibrium approach. This comparison is
+systematically carried out for the hard-sphere fluid by computing numerically
+the transport coefficients, the spectral functions, and their poles as a
+function of the wave number in the hydrodynamic limit. The study shows the
+consistency between the two approaches for the determination of the transport
+properties.",2305.06287v1
+2023-06-08,Temperature anomalies of oscillating diffusion in ac-driven periodic systems,"We analyse the impact of temperature on the diffusion coefficient of an
+inertial Brownian particle moving in a symmetric periodic potential and driven
+by a symmetric time-periodic force. Recent studies have revealed the low
+friction regime in which the diffusion coefficient shows giant damped
+quasi-periodic oscillations as a function of the amplitude of the time-periodic
+force [I. G. Marchenko et al., Chaos 32, 113106 (2022)]. We find out that when
+temperature grows the diffusion coefficient increases at its minima, however,
+it decreases at the maxima within a finite temperature window. This curious
+behavior is explained in terms of the deterministic dynamics perturbed by
+thermal fluctuations and mean residence time of the particle in the locked and
+running trajectories. We demonstrate that temperature dependence of the
+diffusion coefficient can be accurately reconstructed from the stationary
+probability to occupy the running trajectories.",2306.04977v1
+2024-03-22,Investigating the Relationship between Simulation Parameters and Flow Variables in Simulating Atmospheric Gravity Waves in Wind Energy Applications,"Wind farms, particularly offshore clusters, are becoming larger than ever
+before. Besides influencing wind farms and local meteorology downstream, large
+wind farms can trigger atmospheric gravity waves in the inversion layer and the
+free atmosphere aloft. Wind farm-induced gravity waves can cause adverse
+pressure gradients upstream of the wind farm, that contribute to the global
+blockage effect, and favorable pressure gradients above and downstream of the
+wind farm that enhance wake recovery.
+  Numerical modeling is a powerful means of studying wind farm-induced
+atmospheric gravity waves, but it comes with the challenge of handling spurious
+reflections of these waves from domain boundaries. Approaches like radiation
+boundary conditions and forcing zones are used to avoid the reflections.
+However, the simulation setup heavily relies on ad-hoc processes. For instance,
+the widely used Rayleigh damping method requires ad-hoc tuning to acquire a
+setup only applicable to a particular case. To surmount this hurdle, we conduct
+a systematic LES study for flow over a 2D hill and through wind farm canopies
+that explores the dependence of domain size and damping layer setup on
+parameters driving linearly stratified atmospheric flows.
+  Mainly the internal waves in the free atmosphere reflect from the boundaries,
+therefore by simulation linearly stratified conditions we focus on internal
+waves only. The Froude number drives most of the internal wave properties, such
+as wavelengths, amplitude, and direction. Therefore, the domain sizing and
+Rayleigh damping layer setup mainly depends on the Froude number. We
+anticipated the effective wavelengths to be the correct length scale to size
+the domain and damping layer thickness. Also, the damping coefficient is scaled
+with Brunt-V\""ais\""al\""a frequency.",2403.18863v1
+2000-02-23,Two-frequency forced Faraday waves: Weakly damped modes and pattern selection,"Recent experiments (Kudrolli, Pier and Gollub, 1998) on two-frequency
+parametrically excited surface waves exhibit an intriguing ""superlattice"" wave
+pattern near a codimension-two bifurcation point where both subharmonic and
+harmonic waves onset simultaneously, but with different spatial wavenumbers.
+The superlattice pattern is synchronous with the forcing, spatially periodic on
+a large hexagonal lattice, and exhibits small-scale triangular structure.
+Similar patterns have been shown to exist as primary solution branches of a
+generic 12-dimensional $D_6\dot{+}T^2$-equivariant bifurcation problem, and may
+be stable if the nonlinear coefficients of the bifurcation problem satisfy
+certain inequalities (Silber and Proctor, 1998). Here we use the spatial and
+temporal symmetries of the problem to argue that weakly damped harmonic waves
+may be critical to understanding the stabilization of this pattern in the
+Faraday system. We illustrate this mechanism by considering the equations
+developed by Zhang and Vinals (1997, J. Fluid Mech. 336) for small amplitude,
+weakly damped surface waves on a semi-infinite fluid layer. We compute the
+relevant nonlinear coefficients in the bifurcation equations describing the
+onset of patterns for excitation frequency ratios of 2/3 and 6/7. For the 2/3
+case, we show that there is a fundamental difference in the pattern selection
+problems for subharmonic and harmonic instabilities near the codimension-two
+point. Also, we find that the 6/7 case is significantly different from the 2/3
+case due to the presence of additional weakly damped harmonic modes. These
+additional harmonic modes can result in a stabilization of the superpatterns.",0002041v2
+2007-12-28,Role of antikaon condensation in r-mode instability,"We investigate the effect of antikaon condensed matter on bulk viscosity in
+rotating neutron stars. We use relativistic field theoretical models to
+construct the equation of state of neutron stars with the condensate, where the
+phase transition from nucleonic to $K^-$ condensed phase is assumed to be of
+first order. We calculate the coefficient of bulk viscosity due to the
+non-leptonic weak interaction n --> p + K^-. The influence of antikaon bulk
+viscosity on the gravitational radiation reaction driven instability in the
+r-modes is investigated. We compare our results with the previously studied
+non-leptonic weak interaction $n + p --> p + \Lambda$ involving hyperons on the
+damping of the r-mode oscillations.
+  We find that the bulk viscosity coefficient due to the non-leptonic weak
+process involving the condensate is suppressed by several orders of magnitude
+in comparison with the non-superfluid hyperon bulk viscosity coefficient.
+Consequently, the antikaon bulk viscosity may not be able to damp the r-mode
+instability, while hyperon bulk viscosity can effectively suppress r-mode
+oscillations at low temperatures. Hence neutron stars containing $K^-$
+condensate in their core could be possible sources of gravitational waves.",0712.4347v1
+2020-03-30,DAMPE proton spectrum indicates a slow-diffusion zone in the nearby ISM,"The hardening and softening features in the DAMPE proton spectrum are very
+likely to be originated from a nearby supernova remnant (SNR). The proton
+spectrum from the nearby SNR is required to be very hard below $\approx10$ TeV.
+To reproduce this feature, we illustrate that anomalously slow-diffusion zone
+for cosmic rays (CRs) must be existed in the local interstellar medium (ISM)
+after also taking the dipole anisotropy of CRs into account. Assuming that the
+diffusion coefficient is homogeneous in the nearby ISM, we show that the
+diffusion coefficient is constrained to the magnitude of $10^{26}$ cm$^2$
+s$^{-1}$ when normalized to 1 GeV, which is about 100 times smaller than the
+average value in the Galaxy. We further discuss the spatial distribution of the
+slow diffusion and find two distinct possibilities. In one case, the SNR is
+several hundred of parsecs away from the solar system, meanwhile both the SNR
+and the solar system are required to be included in a large slow-diffusion
+zone. The homogeneous diffusion belongs to this case. In the other case, the
+SNR is very close with a distance of $\sim50$ pc and the slow-diffusion zone is
+only limited around the SNR. The required diffusion coefficient is further
+smaller in the latter case. This work provides a new way of studying the CR
+diffusion in the local ISM.",2003.13635v1
+2021-08-20,Cosmic-Ray Transport in Simulations of Star-forming Galactic Disks,"Cosmic ray transport on galactic scales depends on the detailed properties of
+the magnetized, multiphase interstellar medium (ISM). In this work, we
+post-process a high-resolution TIGRESS magnetohydrodynamic simulation modeling
+a local galactic disk patch with a two-moment fluid algorithm for cosmic ray
+transport. We consider a variety of prescriptions for the cosmic rays, from a
+simple purely diffusive formalism with constant scattering coefficient, to a
+physically-motivated model in which the scattering coefficient is set by
+critical balance between streaming-driven Alfv\'en wave excitation and damping
+mediated by local gas properties. We separately focus on cosmic rays with
+kinetic energies of $\sim 1$ GeV (high-energy) and $\sim 30$~MeV (low-energy),
+respectively important for ISM dynamics and chemistry. We find that
+simultaneously accounting for advection, streaming, and diffusion of cosmic
+rays is crucial for properly modeling their transport. Advection dominates in
+the high-velocity, low-density, hot phase, while diffusion and streaming are
+more important in higher density, cooler phases. Our physically-motivated model
+shows that there is no single diffusivity for cosmic-ray transport: the
+scattering coefficient varies by four or more orders of magnitude, maximal at
+density $n_\mathrm{H} \sim 0.01\, \mathrm{cm}^{-3}$. Ion-neutral damping of
+Alfv\'en waves results in strong diffusion and nearly uniform cosmic ray
+pressure within most of the mass of the ISM. However, cosmic rays are trapped
+near the disk midplane by the higher scattering rate in the surrounding
+lower-density, higher-ionization gas. The transport of high-energy cosmic rays
+differs from that of low-energy cosmic rays, with less effective diffusion and
+greater energy losses for the latter.",2108.09356v1
+2021-08-29,Sound induced by a simple impact oscillator,"Acoustic radiation due to vibration and impact of a spring-mass-damper
+oscillator whose motion is constrained by a barrier is analyzed at a field
+point in a free field. Impact between the mass and the barrier is modeled using
+a coefficient of restitution model. Non-linear behavior of the oscillator is
+observed due to motion constraint. Steady state response is studied using a
+bifurcation diagram. For small amplitudes of oscillation, the pressure
+perturbation by a vibrating mass in a compressible fluid is modeled as an
+acoustic dipole with its center at the equilibrium position of the mass and its
+axis aligned with the motion of the oscillator. The boundary condition for the
+acoustic domain is an acoustic free-field condition. It is observed that the
+unsteady acoustic pressure resulting from the impact force is a few orders of
+magnitude greater relative to the pressure field resulting from vibration alone
+before or after impact. We also analyzed the influence of coefficient of
+restitution, damping ratio, the ration of base excitation frequency to the
+natural frequency, and the ratio of the distance of the barrier to the base
+excitation amplitude on the acoustic radiation. Damping ratio and coefficient
+of restituion are shown to be the most significant paramters that affect the
+acoustic radiation from the vibro-impact oscillator.",2108.12804v1
+2022-04-30,A spectral element solution of the 2D linearized potential flow radiation problem,"We present a scalable 2D Galerkin spectral element method solution to the
+linearized potential flow radiation problem for wave induced forcing of a
+floating offshore structure. The pseudo-impulsive formulation of the problem is
+solved in the time-domain using a Gaussian displacement signal tailored to the
+discrete resolution. The added mass and damping coefficients are then obtained
+via Fourier transformation. The spectral element method is used to discretize
+the spatial fluid domain, whereas the classical explicit 4-stage 4th order
+Runge-Kutta scheme is employed for the temporal integration. Spectral
+convergence of the proposed model is established for both affine and
+curvilinear elements, and the computational effort is shown to scale with
+$\mathcal{O}(N^p)$, with $N$ begin the total number of grid points and $p
+\approx 1$. Temporal stability properties, caused by the spatial resolution,
+are considered to ensure a stable model. The solver is used to compute the
+hydrodynamic coefficients for several floating bodies and compare against known
+public benchmark results. The results are showing excellent agreement,
+ultimately validating the solver and emphasizing the geometrical flexibility
+and high accuracy and efficiency of the proposed solver strategy. Lastly, an
+extensive investigation of non-resolved energy from the pseudo-impulse is
+carried out to characterise the induced spurious oscillations of the free
+surface quantities leading to a verification of a proposal on how to
+efficiently and accurately calculate added mass and damping coefficients in
+pseudo-impulsive solvers.",2205.00184v1
+2007-02-23,Organization of the Modulopt collection of optimization problems in the Libopt environment -- Version 1.0,"This note describes how the optimization problems of the Modulopt collection
+are organized within the Libopt environment. It is aimed at being a guide for
+using and enriching this collection in this environment.",0702695v1
+2005-10-17,"Comment on ""Operator Quantum Error Correction""","The attempt to equate operator quantum error correction (quant-ph/0504189v1)
+with the quantum computer condition (quant-ph/0507141) in version two of
+quant-ph/0504189 is shown to be invalid.",0510116v1
+2007-09-17,H-Decompositions,"We show that for all graphs H of size n, the complete graph $K_{2n+1}$ has an
+$H$-decomposition.",0709.2525v5
+2008-10-06,Unsolvability of the isomorphism problem for [free abelian]-by-free groups,The isomorphism problem for [free abelian]-by-free groups is unsolvable.,0810.0935v2
+2011-11-27,"Comment on ""Capturing correlations in chaotic diffusion by approximation methods""","This is a comment on [G. Knight and R. Klages, Phys. Rev. E 84, 041135
+(2011); also available at arXiv:1107.5293v2 [math-ph]].",1111.6271v1
+2014-01-11,Hashimoto transform for stochastic Landau-Lifshitz-Gilbert equation,"We show that Hashimoto transformation is applicable to the one dimensional
+stochastic Landau-Lifshitz-Gilbert (LLG) equation and transforms it to the
+stochastic generalized heat equation with nonlocal (in space) interaction.",1401.2520v1
+2017-01-04,Non-linear Cyclic Codes that Attain the Gilbert-Varshamov Bound,"We prove that there exist non-linear binary cyclic codes that attain the
+Gilbert-Varshamov bound.",1701.01043v1
+2019-01-28,Conformal deformations preserving the Finslerian $R$-Einstein criterion,"Given a Finslerian metric $F$ on a $C^4$-manifold, conformal deformations of
+$F$ preserving the $R$-Einstein criterion are presented. In particular, locally
+conformal invariance between two Finslerian $R$-Einstein metrics is
+characterized.",1902.00069v1
+2022-04-07,How to design a network architecture using availability,"The best way to design a network is to take into account Availability values
+and Capacity Planning. You already saw Availability expressed with numbers such
+as 99.99%. The purpose of this document is to introduce the way to compute
+Availability values using Reliability Block Diagrams.",2204.03311v1
+2022-01-06,Parameter-free quantum hydrodynamic theory for plasmonics: Electron density-dependent damping rate and diffusion coefficient,"Plasmonics is a rapid growing field, which has enabled both fundamental
+science and inventions of various quantum optoelectronic devices. An accurate
+and efficient method to calculate the optical response of metallic structures
+with feature size in the nanoscale plays an important role. Quantum
+hydrodynamic theory (QHT) provides an efficient description of the
+free-electron gas, where quantum effects of nonlocality and spill-out are taken
+into account. In this work, we introduce a general QHT that includes diffusion
+to account for the broadening, which is a key problem in practical applications
+of surface plasmon. We will introduce a density-dependent diffusion coefficient
+to give very accurate linewidth. It is a self-consistent method, in which both
+the ground and excited states are solved by using the same energy functional,
+with the kinetic energy described by the Thomas-Fermi and von Weizs\""{a}cker
+(vW) formalisms. In addition, our QHT method is stable by introduction of an
+electron density-dependent damping rate. For sodium nanosphere of various
+sizes, the plasmon energy and broadening by our QHT method are in excellent
+agreement with those by density functional theory and Kreibig formula. By
+applying our QHT method to sodium jellium nanorods, we clearly show that our
+method enables a parameter-free simulation, i.e. without resorting to any
+empirical parameter, such as size-dependent damping rate and diffusing
+coefficient. It is found that there exists a perfect linear relation between
+the resonance wavelength and aspect radio. The width decreases with increasing
+aspect ratio and height. The calculations show that our QHT method provides an
+explicit and unified way to account for size-dependent frequency shifts and
+broadening of arbitrarily shaped geometries. It is reliable and robust with
+great predicability, and hence provides a general and efficient platform to
+study plasmonics.",2201.03426v3
+2010-02-22,Transport and magnetization dynamics in a superconductor/single-molecule magnet/superconductor junction,"We study dc-transport and magnetization dynamics in a junction of arbitrary
+transparency consisting of two spin-singlet superconducting leads connected via
+a single classical spin precessing at the frequency $\Omega$. The presence of
+the spin in the junction provides different transmission amplitudes for spin-up
+and spin-down quasiparticles as well as a time-dependent spin-flip transmission
+term. For a phase biased junction, we show that a steady-state superconducting
+charge current flows through the junction and that an out-of-equilibrium
+circularly polarized spin current, of frequency $\Omega$, is emitted in the
+leads. Detailed understanding of the charge and spin currents is obtained in
+the entire parameter range. In the adiabatic regime, $\hbar \Omega \ll 2\Delta$
+where $\Delta$ is the superconducting gap, and for high transparencies of the
+junction, a strong suppression of the current takes place around $\vp \approx
+0$ due to an abrupt change in the occupation of the Andreev bound-states. At
+higher values of the phase and/or precession frequency, extended
+(quasi-particle like) states compete with the bound-states in order to carry
+the current. Well below the superconducting transition, these results are shown
+to be weakly affected by the back-action of the spin current on the dynamics of
+the precessing spin. Indeed, we show that the Gilbert damping due to the
+quasi-particle spin current is strongly suppressed at low-temperatures, which
+goes along with a shift of the precession frequency due to the condensate. The
+results obtained may be of interest for on-going experiments in the field of
+molecular spintronics.",1002.3929v4
+2013-06-18,"Baryons do trace dark matter 380,000 years after the big bang: Search for compensated isocurvature perturbations with WMAP 9-year data","Primordial isocurvature fluctuations between photons and either neutrinos or
+non-relativistic species such as baryons or dark matter are known to be
+sub-dominant to adiabatic fluctuations. Perturbations in the relative densities
+of baryons and dark matter (known as compensated isocurvature perturbations, or
+CIPs), however, are surprisingly poorly constrained. CIPs leave no imprint in
+the cosmic microwave background (CMB) on observable scales, at least at linear
+order in their amplitude and zeroth order in the amplitude of adiabatic
+perturbations. It is thus not yet empirically known if baryons trace dark
+matter at the surface of last scattering. If CIPs exist, they would spatially
+modulate the Silk damping scale and acoustic horizon, causing distinct
+fluctuations in the CMB temperature/polarization power spectra across the sky:
+this effect is first order in both the CIP and adiabatic mode amplitudes. Here,
+temperature data from the Wilkinson Microwave Anisotropy Probe (WMAP) are used
+to conduct the first CMB-based observational search for CIPs, using
+off-diagonal correlations and the CMB trispectrum. Reconstruction noise from
+weak lensing and point sources is shown to be negligible for this data set. No
+evidence for CIPs is observed, and a 95%-confidence upper limit of $1.1\times
+10^{-2}$ is imposed to the amplitude of a scale-invariant CIP power spectrum.
+This limit agrees with CIP sensitivity forecasts for WMAP, and is competitive
+with smaller scale constraints from measurements of the baryon fraction in
+galaxy clusters. It is shown that the root-mean-squared CIP amplitude on 5-100
+degree scales is smaller than 0.07-0.17 (depending on the scale) at the
+95%-confidence level. Temperature data from the Planck satellite will provide
+an even more sensitive probe for the existence of CIPs, as will the upcoming
+ACTPol and SPTPol experiments on smaller angular scales.",1306.4319v1
+2015-05-29,Microscopic Theory for Coupled Atomistic Magnetization and Lattice Dynamics,"A coupled atomistic spin and lattice dynamics approach is developed which
+merges the dynamics of these two degrees of freedom into a single set of
+coupled equations of motion. The underlying microscopic model comprises local
+exchange interactions between the electron spin and magnetic moment and the
+local couplings between the electronic charge and lattice displacements. An
+effective action for the spin and lattice variables is constructed in which the
+interactions among the spin and lattice components are determined by the
+underlying electronic structure. In this way, expressions are obtained for the
+electronically mediated couplings between the spin and lattice degrees of
+freedom, besides the well known inter-atomic force constants and spin-spin
+interactions. These former susceptibilities provide an atomistic ab initio
+description for the coupled spin and lattice dynamics. It is important to
+notice that this theory is strictly bilinear in the spin and lattice variables
+and provides a minimal model for the coupled dynamics of these subsystems and
+that the two subsystems are treated on the same footing. Questions concerning
+time-reversal and inversion symmetry are rigorously addressed and it is shown
+how these aspects are absorbed in the tensor structure of the interaction
+fields. By means of these results regarding the spin-lattice coupling, simple
+explanations of ionic dimerization in double anti-ferromagnetic materials, as
+well as, charge density waves induced by a non-uniform spin structure are
+given. In the final parts, a set of coupled equations of motion for the
+combined spin and lattice dynamics are constructed, which subsequently can be
+reduced to a form which is analogous to the Landau-Lifshitz-Gilbert equations
+for spin dynamics and damped driven mechanical oscillator for the ...",1505.08005v3
+2016-04-28,Dynamics of skyrmionic states in confined helimagnetic nanostructures,"In confined helimagnetic nanostructures, skyrmionic states in the form of
+incomplete and isolated skyrmion states can emerge as the ground state in
+absence of both external magnetic field and magnetocrystalline anisotropy. In
+this work, we study the dynamic properties (resonance frequencies and
+corresponding eigenmodes) of skyrmionic states in thin film FeGe disk samples.
+We employ two different methods in finite-element based micromagnetic
+simulation: eigenvalue and ringdown method. The eigenvalue method allows us to
+identify all resonance frequencies and corresponding eigenmodes that can exist
+in the simulated system. However, using a particular experimentally feasible
+excitation can excite only a limited set of eigenmodes. Because of that, we
+perform ringdown simulations that resemble the experimental setup using both
+in-plane and out-of-plane excitations. In addition, we report the nonlinear
+dependence of resonance frequencies on the external magnetic bias field and
+disk sample diameter and discuss the possible reversal mode of skyrmionic
+states. We compare the power spectral densities of incomplete skyrmion and
+isolated skyrmion states and observe several key differences that can
+contribute to the experimental identification of the state present in the
+sample. We measure the FeGe Gilbert damping, and using its value we determine
+what eigenmodes can be expected to be observed in experiments. Finally, we show
+that neglecting the demagnetisation energy contribution or ignoring the
+magnetisation variation in the out-of-film direction - although not changing
+the eigenmode's magnetisation dynamics significantly - changes their resonance
+frequencies substantially. Apart from contributing to the understanding of
+skyrmionic states physics, this systematic work can be used as a guide for the
+experimental identification of skyrmionic states in confined helimagnetic
+nanostructures.",1604.08347v2
+2017-04-13,Low energy magnon dynamics and magneto-optics of the skyrmionic Mott insulator Cu$_2$OSeO$_3$,"In this work, we present a comprehensive study of the low energy optical
+magnetic response of the skyrmionic Mott insulator Cu$_2$OSeO$_3$ via high
+resolution time-domain THz spectroscopy. In zero field, a new magnetic
+excitation not predicted by spin-wave theory with frequency $f$ = 2.03 THz is
+observed and shown, with accompanying time-of-flight neutron scattering
+experiments, to be a zone folded magnon from the $\mathrm{R}$ to
+$\mathrm{\Gamma}$ points of the Brillouin zone. Highly sensitive polarimetry
+experiments performed in weak magnetic fields, $\mu_0$H $<$ 200 mT, observe
+Faraday and Kerr rotations which are proportional to the sample magnetization,
+allowing for optical detection of the skyrmion phase and construction of a
+magnetic phase diagram. From these measurements, we extract a critical exponent
+of $\beta$ = 0.35 $\pm$ 0.04, in good agreement with the expected value for the
+3D Heisenberg universality class of $\beta$ = 0.367. In large magnetic fields,
+$\mu_0$H $>$ 5 T, we observe the magnetically active uniform mode of the
+ferrimagnetic field polarized phase whose dynamics as a function of field and
+temperature are studied. In addition to extracting a $g_\text{eff}$ = 2.08
+$\pm$ 0.03, we observe the uniform mode to decay through a non-Gilbert damping
+mechanism and to possesses a finite spontaneous decay rate, $\Gamma_0$
+$\approx$ 25 GHz, in the zero temperature limit. Our observations are
+attributed to Dzyaloshinkii-Moriya interactions, which have been proposed to be
+exceptionally strong in Cu$_2$OSeO$_3$ and are expected to impact the low
+energy magnetic response of such chiral magnets.",1704.04228v1
+2017-08-25,Role of dimensional crossover on spin-orbit torque efficiency in magnetic insulator thin films,"Magnetic insulators (MIs) attract tremendous interest for spintronic
+applications due to low Gilbert damping and absence of Ohmic loss. Magnetic
+order of MIs can be manipulated and even switched by spin-orbit torques (SOTs)
+generated through spin Hall effect and Rashba-Edelstein effect in heavy
+metal/MI bilayers. SOTs on MIs are more intriguing than magnetic metals since
+SOTs cannot be transferred to MIs through direct injection of electron spins.
+Understanding of SOTs on MIs remains elusive, especially how SOTs scale with
+the film thickness. Here, we observe the critical role of dimensionality on the
+SOT efficiency by systematically studying the MI layer thickness dependent SOT
+efficiency in tungsten/thulium iron garnet (W/TmIG) bilayers. We first show
+that the TmIG thin film evolves from two-dimensional to three-dimensional
+magnetic phase transitions as the thickness increases, due to the suppression
+of long-wavelength thermal fluctuation. Then, we report the significant
+enhancement of the measured SOT efficiency as the thickness increases. We
+attribute this effect to the increase of the magnetic moment density in concert
+with the suppression of thermal fluctuations. At last, we demonstrate the
+current-induced SOT switching in the W/TmIG bilayers with a TmIG thickness up
+to 15 nm. The switching current density is comparable with those of heavy
+metal/ferromagnetic metal cases. Our findings shed light on the understanding
+of SOTs in MIs, which is important for the future development of ultrathin
+MI-based low-power spintronics.",1708.07584v2
+2018-07-04,Phase Boundary Exchange Coupling in the Mixed Magnetic Phase Regime of a Pd-doped FeRh Epilayer,"Spin-wave resonance measurements were performed in the mixed magnetic phase
+regime of a Pd-doped FeRh epilayer that appears as the first-order
+ferromagnetic-antiferromagnetic phase transition takes place. It is seen that
+the measured value of the exchange stiffness is suppressed throughout the
+measurement range when compared to the expected value of the fully
+ferromagnetic regime, extracted via the independent means of a measurement of
+the Curie point, for only slight changes in the ferromagnetic volume fraction.
+This behavior is attributed to the influence of the antiferromagnetic phase:
+inspired by previous experiments that show ferromagnetism to be most persistent
+at the surfaces and interfaces of FeRh thin films, we modelled the
+antiferromagnetic phase as forming a thin layer in the middle of the epilayer
+through which the two ferromagnetic layers are coupled up to a certain critical
+thickness. The development of this exchange stiffness is then consistent with
+that expected from the development of an exchange coupling across the magnetic
+phase boundary, as a consequence of a thickness dependent phase transition
+taking place in the antiferromagnetic regions and is supported by complimentary
+computer simulations of atomistic spin-dynamics. The development of the Gilbert
+damping parameter extracted from the ferromagnetic resonance investigations is
+consistent with this picture.",1807.01615v6
+2018-07-26,EPIC 246851721 b: A Tropical Jupiter Transiting a Rapidly Rotating Star in a Well-Aligned Orbit,"We report the discovery of EPIC 246851721 b, a ""tropical"" Jupiter in a
+6.18-day orbit around the bright ($V=11.439$) star EPIC 246851721 (TYC
+1283-739-1). We present a detailed analysis of the system using $K2$ and
+ground-based photometry, radial velocities, Doppler tomography and adaptive
+optics imaging. From our global models, we infer that the host star is a
+rapidly rotating ($v \sin i = 74.92 $ km s$^{-1}$) F dwarf with
+$T_\mathrm{eff}$ = 6202 K, $R_\star = 1.586 \ R_\odot$ and $M_\star= 1.317 \
+M_\odot$. EPIC 246851721 b has a radius of $1.051 \pm 0.044 R_J$, and a mass of
+3.0$^{+1.1}_{-1.2} M_J$ . Doppler tomography reveals an aligned spin-orbit
+geometry, with a projected obliquity of $-1.47^{\circ\ +0.87}_{\ -0.86}$,
+making EPIC 246851721 the fourth hottest star to host a Jovian planet with $P >
+5$ days and a known obliquity. Using quasi-periodic signatures in its light
+curve that appear to be spot modulations, we estimate the star's rotation
+period, and thereby infer the true obliquity of the system to be $3.7^{\circ\
++3.7}_{\ -1.8}$. We argue that this near-zero obliquity is likely to be
+primordial rather than a result of tidal damping. The host star also has a
+bound stellar companion, a $0.4 \ M_\odot$ M dwarf at a projected separation of
+2100 AU, but the companion is likely incapable of emplacing EPIC 246851721 b in
+its current orbit via high eccentricity Kozai-Lidov migration.",1807.10298v2
+2018-09-10,Magnetic properties and field-driven dynamics of chiral domain walls in epitaxial Pt/Co/Au$_x$Pt$_{1-x}$ trilayers,"Chiral domain walls in ultrathin perpendicularly magnetised layers have a
+N\'{e}el structure stabilised by a Dzyaloshinskii-Moriya interaction (DMI) that
+is generated at the interface between the ferromagnet and a heavy metal.
+Different heavy metals are required above and below a ferromagnetic film in
+order to generate the structural inversion asymmetry needed to ensure that the
+DMI arising at the two interfaces does not cancel. Here we report on the
+magnetic properties of epitaxial Pt/Co/Au$_x$Pt$_{1-x}$ trilayers grown by
+sputtering onto sapphire substrates with 0.6 nm thick Co. As $x$ rises from 0
+to 1 a structural inversion asymmetry is generated. We characterise the
+epilayer structure with x-ray diffraction and cross-sectional transmission
+electron microscopy, revealing (111) stacking. The saturation magnetization
+falls as the proximity magnetisation in Pt is reduced, whilst the perpendicular
+magnetic anisotropy $K_\mathrm{u}$ rises. The micromagnetic DMI strength $D$
+was determined using the bubble expansion technique and also rises from a
+negligible value when $x=0$ to $\sim 1$ mJ/m$^2$ for $x = 1$. The depinning
+field at which field-driven domain wall motion crosses from the creep to the
+depinning regime rises from $\sim 40$ to $\sim 70$ mT, attributed to greater
+spatial fluctuations of the domain wall energy with increasing Au
+concentration. Meanwhile, the increase in DMI causes the Walker field to rise
+from $\sim 10$ to $\sim 280$ mT, meaning that only in the $x = 1$ sample is the
+steady flow regime accessible. The full dependence of domain wall velocity on
+driving field bears little resemblance to the prediction of a simple
+one-dimensional model, but can be described very well using micromagnetic
+simulations with a realistic model of disorder. These reveal a rise in Gilbert
+damping as $x$ increases.",1809.03217v2
+2019-09-06,Macrospin analysis of RF excitations within fully perpendicular magnetic tunnel junctions with second order easy-axis magnetic anisotropy contribution,"The conditions of field and voltage for inducing steady state excitations in
+fully perpendicular magnetic tunnel junctions (pMTJs), adapted for memory
+applications, were numerically investigated by the resolution of the
+Landau-Lifshitz-Gilbert equation in the macrospin approach. Both damping-like
+and the field-like spin transfer torque terms were taken into account in the
+simulations, as well as the contribution of the second order uniaxial
+anisotropy term (K2), which has been recently revealed in MgO-based pMTJs. An
+in-plane applied magnetic field balances the out of plane symmetry of the pMTJ
+and allows the signal detection. Using this model, we assessed the states of
+the free layer magnetization as a function of strength of K2 and polar theta_H
+angle of the applied field (varied from 90 to 60 deg.). There are two stable
+states, with the magnetization in-plane or out of plane of the layer, and two
+dynamic states with self-sustained oscillations, called in-plane precession
+state (IPP) or out of plane precession state (OPP). The IPP mode, with
+oscillation frequencies up to 7 GHz, appears only for positive voltages if
+theta_H = 90 deg. However, it shows a more complex distribution when the field
+is slightly tilted out of plane. The OPP mode is excited only if K2 is
+considered and reaches a maximum oscillation frequency of 15 GHz. Large areas
+of dynamic states with high frequencies are obtained for strong values of the
+field-like torque and K2, when applying a slightly tilted external field toward
+the out of plane direction. The non-zero temperature does not modify the phase
+diagrams, but reduces drastically the power spectral density peak amplitudes.",1909.02926v1
+2021-04-21,Atomic Layer Deposition of Yttrium Iron Garnet Thin Films for 3D Magnetic Structures,"A wide variety of new phenomena such as novel magnetization configurations
+have been predicted to occur in three dimensional magnetic nanostructures.
+However, the fabrication of such structures is often challenging due to the
+specific shapes required, such as magnetic tubes and spirals. Furthermore, the
+materials currently used to assemble these structures are predominantly
+magnetic metals that do not allow to study the magnetic response of the system
+separately from the electronic one. In the field of spintronics, the
+prototypical material used for such experiments is the ferrimagnetic insulator
+yttrium iron garnet (Y$_3$Fe$_5$O$_{12}$, YIG). YIG is one of the best
+materials especially for magnonic studies due to its low Gilbert damping. Here,
+we report the first successful fabrication of YIG thin films via atomic layer
+deposition. To that end we utilize a supercycle approach based on the
+combination of sub-nanometer thin layers of the binary systems Fe$_2$O$_3$ and
+Y$_2$O$_3$ in the correct atomic ratio on Y$_3$Al$_5$O$_{12}$ substrates with a
+subsequent annealing step. Our process is robust against typical growth-related
+deviations, ensuring a good reproducibility. The ALD-YIG thin films exhibit a
+good crystalline quality as well as magnetic properties comparable to other
+deposition techniques. One of the outstanding characteristics of atomic layer
+deposition is its ability to conformally coat arbitrarily-shaped substrates.
+ALD hence is the ideal deposition technique to grant an extensive freedom in
+choosing the shape of the magnetic system. The atomic layer deposition of YIG
+enables the fabrication of novel three dimensional magnetic nanostructures,
+which in turn can be utilized for experimentally investigating the phenomena
+predicted in those structures.",2104.10293v2
+2022-11-03,Skyrmion Jellyfish in Driven Chiral Magnets,"Chiral magnets can host topological particles known as skyrmions, which carry
+an exactly quantised topological charge $Q=-1$. In the presence of an
+oscillating magnetic field ${\bf B}_1(t)$, a single skyrmion embedded in a
+ferromagnetic background will start to move with constant velocity ${\bf
+v}_{\text{trans}}$. The mechanism behind this motion is similar to the one used
+by a jellyfish when it swims through water. We show that the skyrmion's motion
+is a universal phenomenon, arising in any magnetic system with translational
+modes. By projecting the equation of motion onto the skyrmion's translational
+modes and going to quadratic order in ${\bf B}_1(t)$, we obtain an analytical
+expression for ${\bf v}_{\text{trans}}$ as a function of the system's linear
+response. The linear response and consequently ${\bf v}_{\text{trans}}$ are
+influenced by the skyrmion's internal modes and scattering states, as well as
+by the ferromagnetic background's Kittel mode. The direction and speed of ${\bf
+v}_{\text{trans}}$ can be controlled by changing the polarisation, frequency
+and phase of the driving field ${\bf B}_1(t)$. For systems with small Gilbert
+damping parameter $\alpha$, we identify two distinct physical mechanisms used
+by the skyrmion to move. At low driving frequencies, the skyrmion's motion is
+driven by friction, and $v_{\text{trans}}\sim\alpha$, whereas at higher
+frequencies above the ferromagnetic gap, the skyrmion moves by magnon emission,
+and $v_{\text{trans}}$ becomes independent of $\alpha$.",2211.01714v5
+2023-04-05,Threshold current of field-free perpendicular magnetization switching using anomalous spin-orbit torque,"Spin-orbit torque (SOT) is a candidate technique in next generation magnetic
+random-access memory (MRAM). Recently, experiments show that some material with
+low-symmetric crystalline or magnetic structures can generate anomalous SOT
+that has an out-of-plane component, which is crucial in switching perpendicular
+magnetization of adjacent ferromagnetic (FM) layer in the field-free condition.
+In this work, we analytically derive the threshold current of field-free
+perpendicular magnetization switching using the anomalous SOT. And we
+numerically calculate the track of the magnetic moment in a FM free layer when
+an applied current is smaller and greater than the threshold current. After
+that, we study the applied current dependence of the switching time and the
+switching energy consumption, which shows the minimum energy consumption
+decreases as out-of-plane torque proportion increases. Then we study the
+dependences of the threshold current on anisotropy strength, out-of-plane
+torque proportion, FM free layer thickness and Gilbert damping constant, and
+the threshold current shows negative correlation with the out-of-plane torque
+proportion and positive correlation with the other three parameters. Finally,
+we demonstrate that when the applied current is smaller than the threshold
+current, although it cannot switch the magnetization of FM free layer, it can
+still equivalently add an effective exchange bias field H_{bias} on the FM free
+layer. The H_{bias} is proportional to the applied current J_{SOT}, which
+facilitates the determination of the anomalous SOT efficiency. This work helps
+us to design new spintronic devices that favor field-free switching
+perpendicular magnetization using the anomalous SOT, and provides a way to
+adjust the exchange bias field, which is helpful in controlling FM layer
+magnetization depinning.",2304.02248v2
+1997-07-15,"Linear Response, Dynamical Friction and the Fluctuation-Dissipation Theorem in Stellar Dynamics","We apply linear response theory to a general, inhomogeneous, stationary
+stellar system, with particular emphasis on dissipative processes analogous to
+Landau damping. Assuming only that the response is causal, we show that the
+irreversible work done by an external perturber is described by the
+anti-Hermitian part of a linear response operator, and damping of collective
+modes is described by the anti-Hermitian part of a related polarization
+operator. We derive an exact formal expression for the response operator, which
+is the classical analog of a well-known result in quantum statistical physics.
+When the self-gravity of the response can be ignored, and the ensemble-averaged
+gravitational potential is integrable, the expressions for the mode energy,
+damping rate, and polarization operator reduce to well-known formulae derived
+from perturbation theory in action-angle variables. In this approximation,
+dissipation occurs only via resonant interaction with stellar orbits or
+collective modes. For stellar systems in thermal equilibrium, the
+anti-Hermitian part of the response operator is directly related to the
+correlation function of the fluctuations. Thus dissipative properties of the
+system are completely determined by the spectrum of density fluctuations---the
+fluctuation-dissipation theorem. In particular, we express the coefficient of
+dynamical friction for an orbiting test particle in terms of the fluctuation
+spectrum; this reduces to the known Chandrasekhar formula in the restrictive
+case of an infinite homogeneous system with a Maxwellian velocity distribution.",9707161v1
+2003-06-10,Oscillations of Bose-Einstein condensates with vortex lattices. II. Finite temperatures,"We derive the finite temperature oscillation modes of a harmonically confined
+Bose-Einstein condensed gas undergoing rigid body rotation supported by a
+vortex lattice in the condensate. The hydrodynamic modes separate into two
+classes corresponding to in-phase (center-of-mass) and counter-phase (relative)
+oscillations of the thermal cloud and the condensate. The in- and counter-phase
+oscillations are independent of each other in the case where the thermal cloud
+is inviscid for all modes studied, except the radial pulsations which couple
+them because the pressure perturbations of the condensate and the thermal cloud
+are governed by different adiabatic indices. If the thermal cloud is viscous,
+the two classes of oscillations are coupled, i.e. each type of motion involves
+simultaneously mass and entropy currents. The counter-phase oscillations are
+damped by the mutual friction between the condensate and the thermal cloud
+mediated by the vortex lattice. The damping is large for the values of the
+drag-to-lift ratio of the order of unity and becomes increasingly ineffective
+in either limit of small or large friction. An experimental measurement of a
+subset of these oscillation modes and their damping rates can provide
+information on the values of the phenomenological mutual friction coefficients,
+and hence the quasiparticle-vortex scattering processes in dilute atomic Bose
+gases.",0306245v2
+2005-01-28,Summation of divergent series and Borel summability for strongly dissipative equations with periodic or quasi-periodic forcing terms,"We consider a class of second order ordinary differential equations
+describing one-dimensional systems with a quasi-periodic analytic forcing term
+and in the presence of damping. As a physical application one can think of a
+resistor-inductor-varactor circuit with a periodic (or quasi-periodic) forcing
+function, even if the range of applicability of the theory is much wider. In
+the limit of large damping we look for quasi-periodic solutions which have the
+same frequency vector of the forcing term, and we study their analyticity
+properties in the inverse of the damping coefficient. We find that already the
+case of periodic forcing terms is non-trivial, as the solution is not analytic
+in a neighbourhood of the origin: it turns out to be Borel-summable. In the
+case of quasi-periodic forcing terms we need Renormalization Group techniques
+in order to control the small divisors arising in the perturbation series. We
+show the existence of a summation criterion of the series in this case also,
+but, however, this can not be interpreted as Borel summability.",0501500v1
+2009-09-30,Dynamic polarization of graphene by moving external charges: random phase approximation,"We evaluate the stopping and image forces on a charged particle moving
+parallel to a doped sheet of graphene by using the dielectric response
+formalism for graphene's $\pi$-electron bands in the random phase approximation
+(RPA). The forces are presented as functions of the particle speed and the
+particle distance for a broad range of charge-carrier densities in graphene. A
+detailed comparison with the results from a kinetic equation model reveal the
+importance of inter-band single-particle excitations in the RPA model for high
+particle speeds. We also consider the effects of a finite gap between graphene
+and a supporting substrate, as well as the effects of a finite damping rate
+that is included through the use of Mermin's procedure. The damping rate is
+estimated from a tentative comparison of the Mermin loss function with a HREELS
+experiment. In the limit of low particle speeds, several analytical results are
+obtained for the friction coefficient that show an intricate relationship
+between the charge-carrier density, the damping rate, and the particle
+distance, which may be relevant to surface processes and electrochemistry
+involving graphene.",0909.5598v3
+2010-03-12,Improving the model of emission from spinning dust: effects of grain wobbling and transient spin-up,"Observations continue to support the interpretation of the anomalous
+microwave foreground as electric dipole radiation from spinning dust grains as
+proposed by Draine and Lazarian (1998ab). In this paper we present a refinement
+of the original model by improving the treatment of a number of physical
+effects. First, we consider a disk-like grain rotating with angular velocity at
+an arbitrary angle with respect to the grain symmetry axis and derive the
+rotational damping and excitation coefficients arising from infrared emission,
+plasma-grain interactions and electric dipole emission. The angular velocity
+distribution and the electric dipole emission spectrum for grains is calculated
+using the Langevin equation, for cases both with and without fast internal
+relaxation. Our results show that, the peak emissivity of spinning dust,
+compared to earlier studies, increases by a factor of ~2 for the Warm Neutral
+Medium (WNM), the Warm Ionized Medium (WIM), the Cold Neutral Medium (CNM) and
+the Photodissociation Region (PDR), and by a factor ~4 for Reflection Nebulae
+(RN). The frequency at the emission peak also increases by factors ~1.4 to ~2
+for these media. The increased emission and peak frequency result from the
+non-sphericity of grain shape and from the anisotropy in damping and excitation
+along directions parallel and perpendicular to the grain symmetry axis. Second,
+we provide a detailed numerical study including transient spin-up of grains by
+single-ion collisions. The impulses broaden the emission spectrum and increase
+the peak emissivity for the CNM, WNM and WIM. In addition, we present an
+improved treatment of rotational excitation and damping by infrared emission.",1003.2638v2
+2013-05-15,Beam energy dependence of the viscous damping of anisotropic flow,"The flow harmonics $v_{2,3}$ for charged hadrons, are studied for a broad
+range of centrality selections and beam collision energies in Au+Au
+($\sqrt{s_{NN}}= 7.7 - 200$ GeV) and Pb+Pb ($\sqrt{s_{NN}}= 2.76$ TeV)
+collisions. They validate the characteristic signature expected for the system
+size dependence of viscous damping at each collision energy studied. The
+extracted viscous coefficients, that encode the magnitude of the ratio of shear
+viscosity to entropy density $\eta/s$, are observed to decrease to an apparent
+minimum as the collision energy is increased from $\sqrt{s_{NN}}= 7.7$ to
+approximately 62.4 GeV; thereafter, they show a slow increase with
+$\sqrt{s_{NN}}$ up to 2.76 TeV. This pattern of viscous damping provides the
+first experimental constraint for $\eta/s$ in the temperature-baryon chemical
+potential ($T, \mu_B$) plane, and could be an initial indication for decay
+trajectories which lie close to the critical end point in the phase diagram for
+nuclear matter.",1305.3341v3
+2014-07-15,C$ν$B damping of primordial gravitational waves and the fine-tuning of the C$γ$B temperature anisotropy,"Damping of primordial gravitational waves due to the anisotropic stress
+contribution owing to the cosmological neutrino background (C$\nu$B) is
+investigated in the context of a radiation-to-matter dominated Universe.
+Besides its inherent effects on the gravitational wave propagation, the
+inclusion of the C$\nu$B anisotropic stress into the dynamical equations also
+affects the tensor mode contribution to the anisotropy of the cosmological
+microwave background (C$\gamma$B) temperature. Given that the fluctuations of
+the C$\nu$B temperature in the (ultra)relativistic regime are driven by a
+multipole expansion, the mutual effects on the gravitational waves and on the
+C$\gamma$B are obtained through a unified prescription for a
+radiation-to-matter dominated scenario. The results are confronted with some
+preliminary results for the radiation dominated scenario. Both scenarios are
+supported by a simplified analytical framework, in terms of a scale independent
+dynamical variable, $k \eta$, that relates cosmological scales, $k$, and the
+conformal time, $\eta$. The background relativistic (hot dark) matter
+essentially works as an effective dispersive medium for the gravitational waves
+such that the damping effect is intensified for the Universe evolving to the
+matter dominated era. Changes on the temperature variance owing to the
+inclusion of neutrino collision terms into the dynamical equations result into
+spectral features that ratify that the multipole expansion coefficients
+$C_{l}^{T}$'s die out for $l \sim 100$.",1407.4058v1
+2014-12-08,Variable frequency characterization of interaction at nanoscale in linear dynamic AFM: an FFM primer,"Using electrostatic coupling between an AFM tip and a metallic surface as a
+test interaction, we here present the measurement of the force between the tip
+and the surface, together with the measurement of the interaction stiffness and
+the associated dissipation. These three quantities constitute a full
+characterization of the interaction at nanoscale. They are measured
+independently, simultaneously and quantitatively at the same place. This is
+made possible thanks to a force feedback method that ensures the DC immobility
+of the tip and to the simultaneous application of a sub-nanometer oscillation
+to the tip. In this established linear regime, stiffness and damping are
+directly obtained from amplitude and phase change measurements. The needed
+information for this linear transformation is solely the lever properties in
+the experimental context. Knowledge of k, its stiffness, its damping
+coefficient and Q0, its first resonance frequency is shown to be sufficient in
+the frequency range we are here exploring. Finally, we demonstrate that this
+method is not restricted to the lever resonance frequency. To the contrary,
+this interaction characterization whose resolution is limited by the Brownian
+motion, can be used at any frequencies with essentially the same performances.
+We believe that simultaneous and independent measurements of force, stiffness
+and damping, out of lever resonance, at nanoscale, and within the context of
+linear response define a new AFM paradigm that we call Force Feedback
+Microscopy (FFM). This article details the use of FFM using a well known and
+easy to implement electrostatic interaction between a regular AFM tip and a
+metallic surface in air.",1412.2640v1
+2016-06-29,On the global existence and blowup of smooth solutions to the multi-dimensional compressible Euler equations with time-depending damping,"In this paper, we are concerned with the global existence and blowup of
+smooth solutions to the multi-dimensional compressible Euler equations with
+time-depending damping \begin{equation*}
+  \partial_t\rho+\operatorname{div}(\rho u)=0, \quad
+  \partial_t(\rho u)+\operatorname{div}\left(\rho u\otimes
+u+p\,I_d\right)=-\alpha(t)\rho u, \quad
+  \rho(0,x)=\bar \rho+\varepsilon\rho_0(x),\quad u(0,x)=\varepsilon u_0(x),
+\end{equation*} where $x=(x_1, \cdots, x_d)\in\Bbb R^d$ $(d=2,3)$, the
+frictional coefficient is $\alpha(t)=\frac{\mu}{(1+t)^\lambda}$ with
+$\lambda\ge0$ and $\mu>0$, $\bar\rho>0$ is a constant, $\rho_0,u_0 \in
+C_0^\infty(\Bbb R^d)$, $(\rho_0,u_0)\not\equiv 0$, $\rho(0,x)>0$, and
+$\varepsilon>0$ is sufficiently small. One can totally divide the range of
+$\lambda\ge0$ and $\mu>0$ into the following four cases:
+  Case 1: $0\le\lambda<1$, $\mu>0$ for $d=2,3$;
+  Case 2: $\lambda=1$, $\mu>3-d$ for $d=2,3$;
+  Case 3: $\lambda=1$, $\mu\le 3-d$ for $d=2$;
+  Case 4: $\lambda>1$, $\mu>0$ for $d=2,3$.
+  \noindent We show that there exists a global $C^{\infty}-$smooth solution
+$(\rho, u)$ in Case 1, and Case 2 with $\operatorname{curl} u_0\equiv 0$, while
+in Case 3 and Case 4, in general, the solution $(\rho, u)$ blows up in finite
+time. Therefore, $\lambda=1$ and $\mu=3-d$ appear to be the critical power and
+critical value, respectively, for the global existence of small amplitude
+smooth solution $(\rho, u)$ in $d-$dimensional compressible Euler equations
+with time-depending damping.",1606.08935v1
+2017-12-22,Low-momentum dynamic structure factor of a strongly interacting Fermi gas at finite temperature: A two-fluid hydrodynamic description,"We provide a description of the dynamic structure factor of a homogeneous
+unitary Fermi gas at low momentum and low frequency, based on the dissipative
+two-fluid hydrodynamic theory. The viscous relaxation time is estimated and is
+used to determine the regime where the hydrodynamic theory is applicable and to
+understand the nature of sound waves in the density response near the
+superfluid phase transition. By collecting the best knowledge on the shear
+viscosity and thermal conductivity known so far, we calculate the various
+diffusion coefficients and obtain the damping width of the (first and second)
+sounds. We find that the damping width of the first sound is greatly enhanced
+across the superfluid transition and very close to the transition the second
+sound might be resolved in the density response for the transferred momentum up
+to the half of Fermi momentum. Our work is motivated by the recent measurement
+of the local dynamic structure factor at low momentum at Swinburne University
+of Technology and the on-going experiment on sound attenuation of a homogeneous
+unitary Fermi gas at Massachusetts Institute of Technology. We discuss how the
+measurement of the velocity and damping width of the sound modes in
+low-momentum dynamic structure factor may lead to an improved determination of
+the universal superfluid density, shear viscosity and thermal conductivity of a
+unitary Fermi gas.",1712.08320v1
+2018-10-17,Resonance-broadened transit time damping of particles in MHD turbulence,"As a fundamental astrophysical process, the scattering of particles by
+turbulent magnetic fields has its physical foundation laid by the
+magnetohydrodynamic (MHD) turbulence theory. In the framework of the modern
+theory of MHD turbulence, we derive a generalized broadened resonance function
+by taking into account both the magnetic fluctuations and nonlinear
+decorrelation of turbulent magnetic fields arising in MHD turbulence, and we
+specify the energy range of particles for the dominance of different broadening
+mechanisms. The broadened resonance allows for scattering of particles beyond
+the energy threshold of the linear resonance. By analytically determining the
+pitch-angle diffusion coefficients for transit time damping (TTD) with slow and
+fast modes, we demonstrate that the turbulence anisotropy of slow modes
+suppresses their scattering efficiency. Furthermore, we quantify the dependence
+of the relative importance between slow and fast modes in TTD scattering on (i)
+particle energy, (ii) plasma $\beta$ (the ratio of gas pressure to magnetic
+pressure), and (iii) damping of MHD turbulence, and we also provide the
+parameter space for the dominance of slow modes. To exemplify its applications,
+we find that among typical partially ionized interstellar phases, in the warm
+neutral medium slow and fast modes have comparable efficiencies in TTD
+scattering of cosmic rays. For low-energy particles, e.g., sub-Alfv\'{e}nic
+charged grains, we show that slow modes always dominate TTD scattering.",1810.07726v1
+2019-05-17,Statics and Dynamics of Polymeric Droplets on Chemically Homogeneous and Heterogeneous Substrates,"We present a molecular dynamics study of the motion of cylindrical polymer
+droplets on striped surfaces. We first consider the equilibrium properties of
+droplets on different surfaces, we show that for small stripes the
+Cassie-Baxter equation gives a good approximation of the equilibrium contact
+angle. As the stripe width becomes non-negligible compared to the dimension of
+the droplets, the droplet has to deform significantly to minimize its free
+energy, this results in a smaller value of the contact angle than the continuum
+model predicts. We then evaluate the slip length, and thus the damping
+coefficient as a function of the stripe width. For very small stripes, the
+heterogeneous surface behaves as an effective surface, with the same damping as
+an homogeneous surface with the same contact angle. However, as the stripe
+width increases, damping at the surface increases until reaching a plateau.
+Afterwards, we study the dynamics of droplets under a bulk force. We show that
+if the stripes are large enough the droplets are pinned until a critical
+acceleration. The critical acceleration increases linearly with stripe width.
+For large enough accelerations, the average velocity increases linearly with
+the acceleration, we show that it can then be predicted by a model depending
+only the size of droplet, viscosity and slip length. We show that the velocity
+of the droplet varies sinusoidally as a function of its position on the
+substrate. On the other hand, for accelerations just above the depinning
+acceleration we observe a characteristic stick-slip motion, with successive
+pinnings and depinnings.",1905.07214v1
+2020-05-22,"Quasinormal modes, shadow and greybody factors of 5D electrically charged Bardeen black holes","We study quasinormal modes (QNMs) in 5D electrically charged Bardeen black
+holes spacetime by considering the scalar and electromagnetic field
+perturbations. The black holes spacetime is an exact solution of Einstein
+gravity coupled to nonlinear electrodynamics in five dimensions, which has
+nonsingular behavior. To calculate QNMs, we use the WKB approximation method up
+to sixth order. Due to the presence of electric charge $q_e > 0$, both the
+scalar and electromagnetic field perturbations decay more slowly when compared
+to the Schwarzschild-Tangherlini black holes. We discover that the scalar field
+perturbations oscillate more rapidly when compared to the electromagnetic field
+perturbations. In terms of damping, the scalar field perturbations damp more
+quickly. Graphically we show that the transmission (reflection) coefficients
+decrease (increase) with an increase in the magnitude of the electric charge
+$q_e$. The emission of gravitational waves allows spacetime to undergo damped
+oscillations due to the nonzero value of the imaginary part, which is always
+negative. The imaginary part of the QNMs frequencies is continuously decreasing
+with an increase in the magnitude of the electric charge $q_e$ for a given mode
+($l,n$). A connection between the QNMs frequencies and the black hole shadow,
+as well as the geometric cross-section in the eikonal limit, is also described.",2005.11080v2
+2020-09-25,Direct computation of nonlinear mapping via normal form for reduced-order models of finite element nonlinear structures,"The direct computation of the third-order normal form for a geometrically
+nonlinear structure discretised with the finite element (FE) method, is
+detailed. The procedure allows to define a nonlinear mapping in order to derive
+accurate reduced-order models (ROM) relying on invariant manifold theory. The
+proposed reduction strategy is direct and simulation free, in the sense that it
+allows to pass from physical coordinates (FE nodes) to normal coordinates,
+describing the dynamics in an invariant-based span of the phase space. The
+number of master modes for the ROM is not a priori limited since a complete
+change of coordinate is proposed. The underlying theory ensures the quality of
+the predictions thanks to the invariance property of the reduced subspace,
+together with their curvatures in phase space that accounts for the nonresonant
+nonlinear couplings. The method is applied to a beam discretised with 3D
+elements and shows its ability in recovering internal resonance at high energy.
+Then a fan blade model is investigated and the correct prediction given by the
+ROMs are assessed and discussed. A method is proposed to approximate an
+aggregate value for the damping, that takes into account the damping
+coefficients of all the slave modes, and also using the Rayleigh damping model
+as input. Frequency-response curves for the beam and the blades are then
+exhibited, showing the accuracy of the proposed method.",2009.12145v1
+2020-10-08,A blow-up result for the wave equation with localized initial data: the scale-invariant damping and mass term with combined nonlinearities,"We are interested in this article in studying the damped wave equation with
+localized initial data, in the \textit{scale-invariant case} with mass term and
+two combined nonlinearities. More precisely, we consider the following
+equation: $$ (E) {1cm} u_{tt}-\Delta
+u+\frac{\mu}{1+t}u_t+\frac{\nu^2}{(1+t)^2}u=|u_t|^p+|u|^q, \quad \mbox{in}\
+\mathbb{R}^N\times[0,\infty), $$ with small initial data. Under some
+assumptions on the mass and damping coefficients, $\nu$ and $\mu>0$,
+respectively, we show that blow-up region and the lifespan bound of the
+solution of $(E)$ remain the same as the ones obtained in \cite{Our2} in the
+case of a mass-free wave equation, it i.e. $(E)$ with $\nu=0$.
+  Furthermore, using in part the computations done for $(E)$, we enhance the
+result in \cite{Palmieri} on the Glassey conjecture for the solution of $(E)$
+with omitting the nonlinear term $|u|^q$. Indeed, the blow-up region is
+extended from $p \in (1, p_G(N+\sigma)]$, where $\sigma$ is given by (1.12)
+below, to $p \in (1, p_G(N+\mu)]$ yielding, hence, a better estimate of the
+lifespan when $(\mu-1)^2-4\nu^2<1$. Otherwise, the two results coincide.
+Finally, we may conclude that the mass term {\it has no influence} on the
+dynamics of $(E)$ (resp. $(E)$ without the nonlinear term $|u|^q$), and the
+conjecture we made in \cite{Our2} on the threshold between the blow-up and the
+global existence regions obtained holds true here.",2010.05455v1
+2021-07-31,Damped inertial dynamics with vanishing Tikhonov regularization: strong asymptotic convergence towards the minimum norm solution,"In a Hilbert space, we provide a fast dynamic approach to the hierarchical
+minimization problem which consists in finding the minimum norm solution of a
+convex minimization problem. For this, we study the convergence properties of
+the trajectories generated by a damped inertial dynamic with Tikhonov
+regularization. When the time goes to infinity, the Tikhonov regularization
+parameter is supposed to tend towards zero, not too fast, which is a key
+property to make the trajectories strongly converge towards the minimizer of
+$f$ of minimum norm. According to the structure of the heavy ball method for
+strongly convex functions, the viscous damping coefficient is proportional to
+the square root of the Tikhonov regularization parameter. Therefore, it also
+converges to zero, which will ensure rapid convergence of values. Precisely,
+under a proper tuning of these parameters, based on Lyapunov's analysis, we
+show that the trajectories strongly converge towards the minimizer of minimum
+norm, and we provide the convergence rate of the values. We show a trade off
+between the property of fast convergence of values, and the property of strong
+convergence towards the minimum norm solution. This study improves several
+previous works where this type of results was obtained under restrictive
+hypotheses.",2108.00203v1
+2021-08-11,Numerical investigation of the formation and stability of homogeneous pairs of soft particles in inertial microfluidics,"We investigate the formation and stability of a pair of identical soft
+capsules in channel flow under mild inertia. We employ a combination of the
+lattice Boltzmann, finite element and immersed boundary methods to simulate the
+elastic particles in flow. Validation tests show excellent agreement with
+numerical results obtained by other research groups. Our results reveal new
+trajectory types that have not been observed for pairs of rigid particles.
+While particle softness increases the likelihood of a stable pair forming, the
+pair stability is determined by the lateral position of the particles. A key
+finding is that stabilisation of the axial distance occurs after lateral
+migration of the particles. During the later phase of pair formation, particles
+undergo damped oscillations that are independent of initial conditions. These
+damped oscillations are driven by a strong hydrodynamic coupling of the
+particle dynamics, particle inertia and viscous dissipation. While the
+frequency and damping coefficient of the oscillations depend on particle
+softness, the pair formation time is largely determined by the initial particle
+positions: the time to form a stable pair grows exponentially with the initial
+axial distance. Our results demonstrate that particle softness has a strong
+impact on the behaviour of particle pairs. The findings could have significant
+ramifications for microfluidic applications where a constant and reliable axial
+distance between particles is required, such as flow cytometry.",2108.05277v1
+2021-11-13,Attenuation of surface modes in granular media,"In this work, an unconsolidated granular medium, made of silica microbeads,
+is experimentally tested in a laboratory setting. The objective is to
+investigate the attenuation mechanisms of vertically polarized seismic waves
+traveling at the surface of unconsolidated substrates that are characterized by
+power-law rigidity profiles. Both geometric spreading and material damping due
+to skeletal dissipation are considered. An electromagnetic shaker is employed
+to excite the granular medium between 300 and 550 Hz, generating linear modes
+that are localized near the surface. A densely sampled section is recorded at
+the surface using a laser vibrometer. The explicit solution of the geometric
+attenuation law of Rayleigh-like waves in layered media is employed to
+calculate the geometric spreading function of the vertically polarized surface
+modes within the granular material. In accordance with recent studies, the
+dynamics of these small-amplitude multi-modal linear waves can be analysed by
+considering the granular medium as perfectly continuous and elastic. By
+performing a non-linear regression analysis on particle displacements,
+extracted from experimental velocity data, we determine the frequency-dependent
+attenuation coefficients, which account for the material damping.
+  The findings of this work show that laboratory-scale physical models can be
+used to study the geometric spreading of vertically polarized seismic waves
+induced by the soil inhomogeneity and characterize the material damping of the
+medium.",2111.07199v1
+2021-11-15,The Interplay of Regularizing Factors in the Model of Upper Hybrid Oscillations of Cold Plasma,"A one-dimensional nonlinear model of the so-called upper hybrid oscillations
+in a magnetoactive plasma is investigated taking into account electron-ion
+collisions. It is known that both the presence of an external magnetic field of
+strength $ B_0 $ and a sufficiently large collisional factor $ \nu $ help
+suppress the formation of a finite-dimensional singularity in a solution
+(breaking of oscillations). Nevertheless, the suppression mechanism is
+different: an external magnetic field increases the oscillation frequency, and
+collisions tend to stabilize the medium and suppress oscillations. In terms of
+the initial data and the coefficients $ B_0 $ and $ \nu $, we establish a
+criterion for maintaining the global smoothness of the solution. Namely, for
+fixed $ B_0 $ and $ \nu \ge 0 $ one can precisely divide the initial data into
+two classes: one leads to stabilization to the equilibrium and the other leads
+to the destruction of the solution in a finite time. Next, we examine the
+nature of the stabilization. We show that for small $ B_0 $ an increase in the
+intensity factor first leads to a change in the oscillatory behavior of the
+solution to monotonic damping, which is then again replaced by oscillatory
+damping. At large values of $ B_0 $, the solution is characterized by
+oscillatory damping regardless of the value of the intensity factor $ \nu $.",2111.07826v3
+2021-11-20,Excitation and Damping of Slow Magnetosonic Waves in Flaring Hot Coronal Loops: Effects of Compressive Viscosity,"Slow magnetosonic waves associated with flares were observed in coronal loops
+by SOHO/SUMER, SDO/AIA in various EUV bandpasses, and other instruments. The
+excitation and damping of slow magnetosonic waves provides information on the
+magnetic, temperature, and density structure of the loops. Recently, it was
+found using 1.5D models that the thermal conduction is suppressed and
+compressive viscosity is enhanced in hot (T>6 MK) flaring coronal loops. We
+model the excitation and dissipation of slow magnetosonic waves in hot coronal
+loops with realistic magnetic geometry, enhanced density, and temperature
+(compared to background corona) guided by EUV observations using 3D MHD
+visco-resistive model. The effects of compressive viscosity tensor component
+along the magnetic field are included with classical and enhanced viscosity
+coefficient values for the first time in 3D MHD coronal loop model. The waves
+are excited by a velocity pulse at the footpoint of the loop at coronal lower
+boundary. The modeling results demonstrate the excitation of the slow
+magnetosonic waves and nonlinear coupling to other wave modes, such as the kink
+and fast magnetosonic. We find significant leakage of the waves from the hot
+coronal loops with small effect of viscous dissipation in cooler (6MK) loops,
+and more significant effects of viscous dissipation in hotter (10.5MK) coronal
+loops. Our results demonstrate that nonlinear 3D MHD models are required to
+fully account for various wave couplings, damping, standing wave formation, and
+viscous dissipation in hot flaring coronal loops. Our viscous 3D MHD code
+provides a new tool for improved coronal seismology.",2111.10696v1
+2022-10-17,Interpretations of the cosmic ray secondary-to-primary ratios measured by DAMPE,"Precise measurements of the boron-to-carbon and boron-to-oxygen ratios by
+DAMPE show clear hardenings around $100$ GeV/n, which provide important
+implications on the production, propagation, and interaction of Galactic cosmic
+rays. In this work we investigate a number of models proposed in literature in
+light of the DAMPE findings. These models can roughly be classified into two
+classes, driven by propagation effects or by source ones. Among these models
+discussed, we find that the re-acceleration of cosmic rays, during their
+propagation, by random magnetohydrodynamic waves may not reproduce sufficient
+hardenings of B/C and B/O, and an additional spectral break of the diffusion
+coefficient is required. The other models can properly explain the hardenings
+of the ratios. However, depending on simplifications assumed, the models differ
+in their quality in reproducing the data in a wide energy range. The models
+with significant re-acceleration effect will under-predict low-energy
+antiprotons but over-predict low-energy positrons, and the models with
+secondary production at sources over-predict high-energy antiprotons. For all
+models high-energy positron excess exists.",2210.09205v3
+2022-12-28,Scattering of the UHECR at small pitch angle by damped plasma waves,"In spite a lot of theoretical and experimental effort that has been achieved
+in ultra-high energy cosmic ray (UHECR) scattering research in last few
+decades, some questions remain unanswered, or partially answered. Two of them,
+that will be in the focus of this paper are: possible source of UHECRs and the
+acceleration mechanism of cosmic rays beyond PeV energies. Small pitch-angle
+scattering of UHECRs and possible confinement has been investigated using
+quasilinear theory in order to analytically calculate pitch-angle Fokker-Planck
+coefficient. CR particles resonantly interact with oblique low frequency damped
+waves. We show that the resonance function is broadened due to damping effects
+and this result is compared with the nonlinear broadening. Unlike the case of
+purely parallel (or antiparallel) propagating waves in slab turbulence, the
+presence of the compressive magnetic field component of oblique fast-mode waves
+allows the cosmic ray particles to resonantly interact with these waves through
+the n = 0 resonance, together with gyroresonance, which strongly influence the
+Hillas limit. The derived results can be used to compute the parallel mean free
+path for all forms of the turbulence spectrum; it has been applied on the
+transport and propagation of CRs close to ultra-high energies in the Galaxy. An
+accurate understanding of particle acceleration in astrophysical sources could
+help to interpret eventual transition from Galactic to extragalactic origin of
+cosmic rays, if any, and the shape of the UHECR spectrum at the highest
+energies.",2212.13755v1
+2001-03-19,Fluctuations in the Cosmic Microwave Background I: Form Factors and their Calculation in Synchronous Gauge,"It is shown that the fluctuation in the temperature of the cosmic microwave
+background in any direction may be evaluated as an integral involving scalar
+and dipole form factors, which incorporate all relevant information about
+acoustic oscillations before the time of last scattering. A companion paper
+gives asymptotic expressions for the multipole coefficient $C_\ell$ in terms of
+these form factors. Explicit expressions are given here for the form factors in
+a simplified hydrodynamic model for the evolution of perturbations.",0103279v2
+2005-08-05,Damping of vortex waves in a superfluid,"The damping of vortex cyclotron modes is investigated within a generalized
+quantum theory of vortex waves. Similarly to the case of Kelvin modes, the
+friction coefficient turns out to be essentially unchanged under such
+oscillations, but it is shown to be affected by appreciable memory corrections.
+On the other hand, the nonequilibrium energetics of the vortex, which is
+investigated within the framework of linear response theory, shows that its
+memory corrections are negligible. The vortex response is found to be of the
+Debye type, with a relaxation frequency whose dependence on temperature and
+impurity concentration reflects the complexity of the heat bath and its
+interaction with the vortex.",0508167v1
+2005-09-02,Inhomogeneous soliton ratchets under two ac forces,"We extend our previous work on soliton ratchet devices [L. Morales-Molina et
+al., Eur. Phys. J. B 37, 79 (2004)] to consider the joint effect of two ac
+forces including non-harmonic drivings, as proposed for particle ratchets by
+Savele'v et al. [Europhys. Lett. 67}, 179 (2004); Phys. Rev. E {\bf 70} 066109
+(2004)]. Current reversals due to the interplay between the phases, frequencies
+and amplitudes of the harmonics are obtained. An analysis of the effect of the
+damping coefficient on the dynamics is presented. We show that solitons give
+rise to non-trivial differences in the phenomenology reported for particle
+systems that arise from their extended character. A comparison with soliton
+ratchets in homogeneous systems with biharmonic forces is also presented. This
+ratchet device may be an ideal candidate for Josephson junction ratchets with
+intrinsic large damping.",0509051v1
+2007-01-16,Influence of Lorentz violation on Dirac quasinormal modes in the Schwarzschild black hole spacetime,"Using the third-order WKB approximation and monodromy methods, we investigate
+the influence of Lorentz violating coefficient $b$ (associated with a special
+axial-vector $b_{\mu}$ field) on Dirac quasinormal modes in the Schwarzschild
+black hole spacetime. At fundamental overtone, the real part decreases linearly
+as the parameter $b$ increases. But the variation of the imaginary part with
+$b$ becomes more complex. For the larger multiple moment $k$, the magnitude of
+imaginary part increases with the increase of $b$, which means that presence of
+Lorentz violation makes Dirac field damps more rapidly. At high overtones, it
+is found that the real part of high-damped quasinormal frequency does not tend
+to zero, which is quite a different from the symptotic Dirac quasinormal modes
+without Lorentz violation.",0701089v1
+1994-01-21,Transport Properties of Quark and Gluon Plasmas,"The kinetic properties of relativistic quark-gluon and electron-photon
+plasmas are described in the weak coupling limit. The troublesome Rutherford
+divergence at small scattering angles is screened by Debye screening for the
+longitudinal or electric part of the interactions. The transverse or magnetic
+part of the interactions is effectively screened by Landau damping of the
+virtual photons and gluons transferred in the QED and QCD interactions
+respectively. Including screening a number of transport coefficients for QCD
+and QED plasmas can be calculated to leading order in the interaction strength,
+including rates of momentum and thermal relaxation, electrical conductivity,
+viscosities, flavor and spin diffusion of both high temperature and degenerate
+plasmas. Damping of quarks and gluons as well as color diffusion in quark-gluon
+plasmas is, however, shown not to be sufficiently screened and the rates
+depends on an infrared cut-off of order the ``magnetic mass"", $m_{\rm mag}\sim
+g^2 T$.",9401300v1
+1991-09-26,The Damping of Energetic Gluons and Quarks in High-Temperature QCD,"When a gluon or a quark is sent through the hot QCD plasma it can be absorbed
+into the ambient heat bath and so can acquire an effective lifetime. At high
+temperatures and for weak couplings the inverse lifetime, or damping rate, for
+energetic quarks and transverse gluons, (those whose momenta satisfy $|\p| \gg
+gT$) is given by $\gamma(\p) = c\; g^2 \log\left({1\over g}\right)\; T +
+O(g^2T)$. We show that very simple arguments suffice both to fix the numerical
+coefficient, $c$, in this expression and to show that the $O(g^2T)$
+contribution is incalculable in perturbation theory without further
+assumptions. For QCD with $N_c$ colours we find (expressed in terms of the
+casimir invariants $C_a=N_c$ and $C_f=(N_c^2-1)/(2N_c)$): $c_g=+{C_a\over
+4\pi}$ for gluons and $c_q=+{C_f\over 4\pi}$ for quarks. These numbers agree
+with the more detailed calculations of Pisarski \etal\ but disagree with those
+of Lebedev and Smilga. The simplicity of the calculation also permits a direct
+verification of the gauge-invariance and physical sign of the result.",9109051v1
+2006-11-21,Renormalization group study of damping in nonequilibrium field theory,"In this paper we shall study whether dissipation in a $\lambda\phi^{4}$ may
+be described, in the long wavelength, low frequency limit, with a simple Ohmic
+term $\kappa\dot{\phi}$, as it is usually done, for example, in studies of
+defect formation in nonequilibrium phase transitions. We shall obtain an
+effective theory for the long wavelength modes through the coarse graining of
+shorter wavelengths. We shall implement this coarse graining by iterating a
+Wilsonian renormalization group transformation, where infinitesimal momentum
+shells are coarse-grained one at a time, on the influence action describing the
+dissipative dynamics of the long wavelength modes. To the best of our
+knowledge, this is the first application of the nonequilibrium renormalization
+group to the calculation of a damping coefficient in quantum field theory.",0611222v1
+1997-03-26,A self-consistent treatment of damped motion for stable and unstable collective modes,"We address the dynamics of damped collective modes in terms of first and
+second moments. The modes are introduced in a self-consistent fashion with the
+help of a suitable application of linear response theory. Quantum effects in
+the fluctuations are governed by diffusion coefficients D_{\mu\nu}. The latter
+are obtained through a fluctuation dissipation theorem generalized to allow for
+a treatment of unstable modes. Numerical evaluations of the D_{\mu\nu} are
+presented. We discuss briefly how this picture may be used to describe global
+motion within a locally harmonic approximation. Relations to other methods are
+discussed, like ""dissipative tunneling"", RPA at finite temperature and
+generalizations of the ""Static Path Approximation"".",9703056v1
+1996-10-01,Exact time evolution and master equations for the damped harmonic oscillator,"Using the exact path integral solution for the damped harmonic oscillator it
+is shown that in general there does not exist an exact dissipative Liouville
+operator describing the dynamics of the oscillator for arbitrary initial bath
+preparations. Exact non-stationary Liouville operators can be found only for
+particular preparations. Three physically meaningful examples are examined. An
+exact new master equation is derived for thermal initial conditions. Second,
+the Liouville operator governing the time-evolution of equilibrium correlations
+is obtained. Third, factorizing initial conditions are studied. Additionally,
+one can show that there are approximate Liouville operators independent of the
+initial preparation describing the long time dynamics under appropriate
+conditions. The general form of these approximate master equations is derived
+and the coefficients are determined for special cases of the bath spectral
+density including the Ohmic, Drude and weak coupling cases. The connection with
+earlier work is discussed.",9610001v1
+2007-01-30,Charge Fluctuation of Dust Grain and Its Impact on Dusty-Acoustic Wave Damping,"We consider the influence of dust charge fluctuations on damping of the
+dust-ion-acoustic waves. It is assumed that all grains have equal masses but
+charges are not constant in time - they may fluctuate in time. The dust charges
+are not really independent of the variations in the plasma potentials. All
+modes will influence the charging mechanism, and feedback will lead to several
+new interesting and unexpected phenomena. The charging of the grains depends on
+local plasma characteristics. If the waves disturb these characteristic, then
+charging of the grains is affected and the grain charge is modified, with a
+resulting feedback on the wave mode. In the case considered here, when the
+temperature of electrons is much greater than the temperature of the ions and
+the temperature of electrons is not great enough for further ionization of the
+ions, we show that attenuation of the acoustic wave depends only on one
+phenomenological coefficient",0701336v1
+1999-10-05,"Uncertainty, entropy and decoherence of the damped harmonic oscillator in the Lindblad theory of open quantum systems","In the framework of the Lindblad theory for open quantum systems, expressions
+for the density operator, von Neumann entropy and effective temperature of the
+damped harmonic oscillator are obtained. The entropy for a state characterized
+by a Wigner distribution function which is Gaussian in form is found to depend
+only on the variance of the distribution function. We give a series of
+inequalities, relating uncertainty to von Neumann entropy and linear entropy.
+We analyze the conditions for purity of states and show that for a special
+choice of the diffusion coefficients, the correlated coherent states (squeezed
+coherent states) are the only states which remain pure all the time during the
+evolution of the considered system. These states are also the most stable under
+evolution in the presence of the environment and play an important role in the
+description of environment induced decoherence.",9910019v1
+2007-12-11,Neutrino oscillations in a stochastic model for space-time foam,"We study decoherence models for flavour oscillations in four-dimensional
+stochastically fluctuating space times and discuss briefly the sensitivity of
+current neutrino experiments to such models. We pay emphasis on demonstrating
+the model dependence of the associated decoherence-induced damping coefficients
+in front of the oscillatory terms in the respective transition probabilities
+between flavours. Within the context of specific models of foam, involving
+point-like D-branes and leading to decoherence-induced damping which is
+inversely proportional to the neutrino energies, we also argue that future
+limits on the relevant decoherence parameters coming from TeV astrophysical
+neutrinos, to be observed in ICE-CUBE, are not far from theoretically expected
+values with Planck mass suppression. Ultra high energy neutrinos from Gamma Ray
+Bursts at cosmological distances can also exhibit in principle sensitivity to
+such effects.",0712.1779v1
+2008-06-06,On the stability of shocks with particle pressure,"We perform a linear stability analysis for corrugations of a Newtonian shock,
+with particle pressure included, for an arbitrary diffusion coefficient. We
+study first the dispersion relation for homogeneous media, showing that,
+besides the conventional pressure waves and entropy/vorticity disturbances, two
+new perturbation modes exist, dominated by the particles' pressure and damped
+by diffusion. We show that, due to particle diffusion into the upstream region,
+the fluid will be perturbed also upstream: we treat these perturbation in the
+short wavelength (WKBJ) regime. We then show how to construct a corrugational
+mode for the shock itself, one, that is, where the shock executes free
+oscillations (possibly damped or growing) and sheds perturbations away from
+itself: this global mode requires the new modes. Then, using the perturbed
+Rankine-Hugoniot conditions, we show that this leads to the determination of
+the corrugational eigenfrequency. We solve numerically the equations for the
+eigenfrequency in the WKBJ regime for the models of Amato and Blasi (2005),
+showing that they are stable. We then discuss the differences between our
+treatment and previous work.",0806.1113v1
+2008-08-26,Nonlinear regularization techniques for seismic tomography,"The effects of several nonlinear regularization techniques are discussed in
+the framework of 3D seismic tomography. Traditional, linear, $\ell_2$ penalties
+are compared to so-called sparsity promoting $\ell_1$ and $\ell_0$ penalties,
+and a total variation penalty. Which of these algorithms is judged optimal
+depends on the specific requirements of the scientific experiment. If the
+correct reproduction of model amplitudes is important, classical damping
+towards a smooth model using an $\ell_2$ norm works almost as well as
+minimizing the total variation but is much more efficient. If gradients (edges
+of anomalies) should be resolved with a minimum of distortion, we prefer
+$\ell_1$ damping of Daubechies-4 wavelet coefficients. It has the additional
+advantage of yielding a noiseless reconstruction, contrary to simple $\ell_2$
+minimization (`Tikhonov regularization') which should be avoided. In some of
+our examples, the $\ell_0$ method produced notable artifacts. In addition we
+show how nonlinear $\ell_1$ methods for finding sparse models can be
+competitive in speed with the widely used $\ell_2$ methods, certainly under
+noisy conditions, so that there is no need to shun $\ell_1$ penalizations.",0808.3472v3
+2010-03-31,Non-Markovian master equation for a damped oscillator with time-varying parameters,"We derive an exact non-Markovian master equation that generalizes the
+previous work [Hu, Paz and Zhang, Phys. Rev. D {\bf 45}, 2843 (1992)] to damped
+harmonic oscillators with time-varying parameters. This is achieved by
+exploiting the linearity of the system and operator solution in Heisenberg
+picture. Our equation governs the non-Markovian quantum dynamics when the
+system is modulated by external devices. As an application, we apply our
+equation to parity kick decoupling problems. The time-dependent dissipative
+coefficients in the master equation are shown to be modified drastically when
+the system is driven by $\pi$ pulses. For coherence protection to be effective,
+our numerical results indicate that kicking period should be shorter than
+memory time of the bath. The effects of using soft pulses in an ohmic bath are
+also discussed.",1003.5975v1
+2011-06-06,Weakly nonlinear stochastic CGL equations,"We consider the linear Schr\""odinger equation under periodic boundary
+condition, driven by a random force and damped by a quasilinear damping: $$
+\frac{d}{dt}u+i\big(-\Delta+V(x)\big) u=\nu \Big(\Delta u-\gr |u|^{2p}u-i\gi
+|u|^{2q}u \Big) +\sqrt\nu\, \eta(t,x).\qquad (*) $$ The force $\eta$ is white
+in time and smooth in $x$. We are concerned with the limiting, as $\nu\to0$,
+behaviour of its solutions on long time-intervals $0\le t\le\nu^{-1}T$, and
+with behaviour of these solutions under the double limit $t\to\infty$ and
+$\nu\to0$. We show that these two limiting behaviours may be described in terms
+of solutions for the {\it system of effective equations for $(*)$} which is a
+well posed semilinear stochastic heat equation with a non-local nonlinearity
+and a smooth additive noise, written in Fourier coefficients. The effective
+equations do not depend on the Hamiltonian part of the perturbation
+$-i\gi|u|^{2q}u$ (but depend on the dissipative part $-\gr|u|^{2p}u$). If $p$
+is an integer, they may be written explicitly.",1106.1158v1
+2011-07-13,Increased Brownian force noise from molecular impacts in a constrained volume,"We report on residual gas damping of the motion of a macroscopic test mass
+enclosed in a nearby housing in the molecular flow regime. The damping
+coefficient, and thus the associated thermal force noise, is found to increase
+significantly when the distance between test mass and surrounding walls is
+smaller than the test mass itself. The effect has been investigated with two
+torsion pendulums of different geometry and has been modelled in a numerical
+simulation whose predictions are in good agreement with the measurements.
+Relevant to a wide variety of small-force experiments, the residual-gas force
+noise power for the test masses in the LISA gravitational wave observatory is
+roughly a factor 15 larger than in an infinite gas volume, though still
+compatible with the target acceleration noise of 3 fm s^-2 Hz^-1/2 at the
+foreseen pressure below 10^-6 Pa.",1107.2520v1
+2011-08-02,PHENIX Measurements of Higher-order Flow Harmonics in Au+Au collisions at Root_s = 200 GeV,"Flow coefficients $v_n$ for $n$ = 2, 3, 4, characterizing the anisotropic
+collective flow in Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV, are
+presented. They indicate the expected growth of viscous damping for sound
+propagation in the quark gluon plasma (QGP) produced in these collisions.
+Hydrodynamical model comparisons which include the effects of initial state
+geometry fluctuations, highlight the role of higher harmonics ($v_{n, n>2}$) as
+a constraint for disentangling the effects of viscosity and initial conditions,
+and suggest a small specific viscosity for the QGP. This viscosity is
+compatible with that obtained via a newly proposed technique
+\cite{Lacey:2011ug} which employs the relative magnitudes of $v_n$ to estimate
+the viscosity, and the ""viscous horizon"" or length-scale which characterizes
+the highest harmonic that survives viscous damping.",1108.0457v1
+2011-12-02,On the simulation of the energy transmission in the forbidden band-gap of a spatially discrete double sine-Gordon system,"In this work, we present a numerical method to consistently approximate
+solutions of a spatially discrete, double sine-Gordon chain which considers the
+presence of external damping. In addition to the finite-difference scheme
+employed to approximate the solution of the difference-differential equations
+of the model under investigation, our method provides positivity-preserving
+schemes to approximate the local and the total energy of the system, in such
+way that the discrete rate of change of the total energy with respect to time
+provides a consistent approximation of the corresponding continuous rate of
+change. Simulations are performed, first of all, to assess the validity of the
+computational technique against known qualitative solutions of coupled
+sine-Gordon and coupled double sine-Gordon chains. Secondly, the method is used
+in the investigation of the phenomenon of nonlinear transmission of energy in
+double sine-Gordon systems; the qualitative effects of the damping coefficient
+on the occurrence of the nonlinear process of supratransmission are briefly
+determined in this work, too.",1112.0595v1
+2013-04-15,Vibrational Resonance in the Morse Oscillator,"We investigate the occurrence of vibrational resonance in both classical and
+quantum mechanical Morse oscillators driven by a biharmonic force. The
+biharmonic force consists of two forces of widely different frequencies \omega
+and \Omega with \Omega>>\omega. In the damped and biharmonically driven
+classical Morse oscillator applying a theoretical approach we obtain an
+analytical expression for the response amplitude at the low-frequency \omega.
+We identify the conditions on the parameters for the occurrence of the
+resonance. The system shows only one resonance and moreover at resonance the
+response amplitude is 1/(d\omega) where d is the coefficient of linear damping.
+When the amplitude of the high-frequency force is varied after resonance the
+response amplitude does not decay to zero but approaches a nonzero limiting
+value. We have observed that vibrational resonance occurs when the sinusoidal
+force is replaced by a square-wave force. We also report the occurrence of
+resonance and anti-resonance of transition probability of quantum mechanical
+Morse oscillator in the presence of the biharmonic external field.",1304.3988v1
+2013-11-27,Encapsulated formulation of the Selective Frequency Damping method,"We present an alternative ""encapsulated"" formulation of the Selective
+Frequency Damping method for finding unstable equilibria of dynamical systems,
+which is particularly useful when analysing the stability of fluid flows. The
+formulation makes use of splitting methods, which means that it can be wrapped
+around an existing time-stepping code as a ""black box"". The method is first
+applied to a scalar problem in order to analyse its stability and highlight the
+roles of the control coefficient $\chi$ and the filter width $\Delta$ in the
+convergence (or not) towards the steady-state. Then the steady-state of the
+incompressible flow past a two-dimensional cylinder at $Re=100$, obtained with
+a code which implements the spectral/hp element method, is presented.",1311.7000v1
+2014-08-04,Collective Dynamics of Interacting Particles in Unsteady Flows,"We use the Fokker-Planck equation and its moment equations to study the
+collective behavior of interacting particles in unsteady one-dimensional flows.
+Particles interact according to a long-range attractive and a short-range
+repulsive potential field known as Morse potential. We assume Stokesian drag
+force between particles and their carrier fluid, and find analytic
+single-peaked traveling solutions for the spatial density of particles in the
+catastrophic phase. In steady flow conditions the streaming velocity of
+particles is identical to their carrier fluid, but we show that particle
+streaming is asynchronous with an unsteady carrier fluid. Using linear
+perturbation analysis, the stability of traveling solutions is investigated in
+unsteady conditions. It is shown that the resulting dispersion relation is an
+integral equation of the Fredholm type, and yields two general families of
+stable modes: singular modes whose eigenvalues form a continuous spectrum, and
+a finite number of discrete global modes. Depending on the value of drag
+coefficient, stable modes can be over-damped, critically damped, or decaying
+oscillatory waves. The results of linear perturbation analysis are confirmed
+through the numerical solution of the fully nonlinear Fokker-Planck equation.",1408.0558v1
+2014-09-01,Damping of Bloch oscillations: Variational solutions of the Boltzmann equation beyond linear response,"Variational solutions of the Boltzmann equation usually rely on the concept
+of linear response. We extend the variational approach for tight-binding models
+at high entropies to a regime far beyond linear response. We analyze both
+weakly interacting fermions and incoherent bosons on a lattice. We consider a
+case where the particles are driven by a constant force, leading to the
+well-known Bloch oscillations, and we consider interactions that are weak
+enough not to overdamp these oscillations. This regime is computationally
+demanding and relevant for ultracold atoms in optical lattices. We derive a
+simple theory in terms of coupled dynamic equations for the particle density,
+energy density, current and heat current, allowing for analytic solutions. As
+an application, we identify damping coefficients for Bloch oscillations in the
+Hubbard model at weak interactions and compute them for a one-dimensional toy
+model. We also approximately solve the long-time dynamics of a weakly
+interacting, strongly Bloch-oscillating cloud of fermionic particles in a
+tilted lattice, leading to a subdiffusive scaling exponent.",1409.0560v2
+2014-12-05,Adaptive Damping and Mean Removal for the Generalized Approximate Message Passing Algorithm,"The generalized approximate message passing (GAMP) algorithm is an efficient
+method of MAP or approximate-MMSE estimation of $x$ observed from a noisy
+version of the transform coefficients $z = Ax$. In fact, for large zero-mean
+i.i.d sub-Gaussian $A$, GAMP is characterized by a state evolution whose fixed
+points, when unique, are optimal. For generic $A$, however, GAMP may diverge.
+In this paper, we propose adaptive damping and mean-removal strategies that aim
+to prevent divergence. Numerical results demonstrate significantly enhanced
+robustness to non-zero-mean, rank-deficient, column-correlated, and
+ill-conditioned $A$.",1412.2005v1
+2014-12-14,An adaptive selective frequency damping method,"The selective frequency damping (SFD) method is an alternative to classical
+Newton's method to obtain unstable steady-state solutions of dynamical systems.
+However this method has two main limitations: it does not converge for
+arbitrary control parameters; and when it does converge, the time necessary to
+reach the steady-state solution may be very long. In this paper we present an
+adaptive algorithm to address these two issues. We show that by evaluating the
+dominant eigenvalue of a ""partially converged"" steady flow, we can select a
+control coefficient and a filter width that ensure an optimum convergence of
+the SFD method. We apply this adaptive method to several classical test cases
+of computational fluid dynamics and we show that a steady-state solution can be
+obtained without any a priori knowledge of the flow stability properties.",1412.4372v1
+2015-04-29,Wide-Range Tunable Dynamic Property of Carbon Nanotube-Based Fibers,"Carbon nanotube (CNT) fiber is formed by assembling millions of individual
+tubes. The assembly feature provides the fiber with rich interface structures
+and thus various ways of energy dissipation, as reflected by the non-zero loss
+tangent (>0.028--0.045) at low vibration frequencies. A fiber containing
+entangled CNTs possesses higher loss tangents than a fiber spun from aligned
+CNTs. Liquid densification and polymer infiltration, the two common ways to
+increase the interfacial friction and thus the fiber's tensile strength and
+modulus, are found to efficiently reduce the damping coefficient. This is
+because the sliding tendency between CNT bundles can also be well suppressed by
+the high packing density and the formation of covalent polymer cross-links
+within the fiber. The CNT/bismaleimide composite fiber exhibited the smallest
+loss tangent, nearly as the same as that of carbon fibers. At a higher level of
+the assembly structure, namely a multi-ply CNT yarn, the inter-fiber friction
+and sliding tendency obviously influence the yarn's damping performance, and
+the loss tangent can be tuned within a wide range, as similar to carbon fibers,
+nylon yarns, or cotton yarns. The wide-range tunable dynamic properties allow
+new applications ranging from high quality factor materials to dissipative
+systems.",1504.07881v1
+2015-05-13,The effect of a reversible shear transformation on plastic deformation of an amorphous solid,"Molecular dynamics simulations are performed to investigate the plastic
+response of a model glass to a local shear transformation in a quiescent
+system. The deformation of the material is induced by a spherical inclusion
+that is gradually strained into an ellipsoid of the same volume and then
+reverted back into the sphere. We show that the number of cage-breaking events
+increases with increasing strain amplitude of the shear transformation. The
+results of numerical simulations indicate that the density of cage jumps is
+larger in the cases of weak damping or slow shear transformation. Remarkably,
+we also found that, for a given strain amplitude, the peak value of the density
+profiles is a function of the ratio of the damping coefficient and the time
+scale of the shear transformation.",1505.03488v1
+2015-10-17,Direct evidence for minority spin gap in the Co2MnSi Heusler alloy,"Half Metal Magnets are of great interest in the field of spintronics because
+of their potential full spin-polarization at the Fermi level and low
+magnetization damping. The high Curie temperature and predicted 0.7eV minority
+spin gap make the Heusler alloy Co2MnSi very promising for applications.We
+investigated the half-metallic magnetic character of this alloy using
+spin-resolved photoemission, ab initio calculation and ferromagnetic resonance.
+At the surface of Co2MnSi, a gap in the minority spin channel is observed,
+leading to 100% spin polarization. However, this gap is 0.3 eV below the Fermi
+level and a minority spin state is observed at the Fermi level. We show that a
+minority spin gap at the Fermi energy can nevertheless be recovered either by
+changing the stoichiometry of the alloy or by covering the surface by Mn, MnSi
+or MgO. This results in extremely small damping coefficients reaching values as
+low as 7x 10-4.",1510.05085v1
+2016-04-06,Brownian motion of a matter-wave bright soliton: realizing a quantum pollen grain,"Taking an open quantum systems approach, we derive a collective equation of
+motion for the dynamics of a matter-wave bright soliton moving through a
+thermal cloud of a distinct atomic species. The reservoir interaction involves
+energy transfer without particle transfer between the soliton and thermal
+cloud, thus damping the soliton motion without altering its stability against
+collapse. We derive a Langevin equation for the soliton centre of mass velocity
+in the form of an Ornstein-Uhlenbeck process with analytical drift and
+diffusion coefficients. This collective motion is confirmed by simulations of
+the full stochastic projected Gross-Pitaevskii equation for the matter-wave
+field. The system offers a pathway for experimentally observing the elusive
+energy-damping reservoir interaction, and a clear realization of collective
+Brownian motion for a mesoscopic superfluid droplet.",1604.01487v1
+2016-04-28,Temperature Dependence of Viscosity in Normal Fluid $^3$He Below 800mK Determined by a Micro-electro-mechanical Oscillator,"A micro-electro-mechanical system vibrating in its shear mode was used to
+study the viscosity of normal liquid $^3$He from 20mK to 770mK at 3bar, 21bar,
+and 29bar. The damping coefficient of the oscillator was determined by
+frequency sweeps through its resonance at each temperature. Using a slide film
+damping model, the viscosity of the fluid was obtained. Our viscosity values
+are compared with previous measurements and with calculated values from Fermi
+liquid theory. The crossover from the classical to the Fermi liquid regime is
+manifest in the temperature dependence of viscosity. In the Fermi liquid
+regime, the temperature dependence of viscosity changes from $T^{-1}$ to
+$T^{-2}$ on cooling, indicating a transition from the Stokes flow to the
+Couette flow regime.",1604.08554v1
+2016-06-11,Parameter identification in a semilinear hyperbolic system,"We consider the identification of a nonlinear friction law in a
+one-dimensional damped wave equation from additional boundary measurements.
+Well-posedness of the governing semilinear hyperbolic system is established via
+semigroup theory and contraction arguments. We then investigte the inverse
+problem of recovering the unknown nonlinear damping law from additional
+boundary measurements of the pressure drop along the pipe. This coefficient
+inverse problem is shown to be ill-posed and a variational regularization
+method is considered for its stable solution. We prove existence of minimizers
+for the Tikhonov functional and discuss the convergence of the regularized
+solutions under an approximate source condition. The meaning of this condition
+and some arguments for its validity are discussed in detail and numerical
+results are presented for illustration of the theoretical findings.",1606.03580v1
+2016-09-15,Low-damping sub-10-nm thin films of lutetium iron garnet grown by molecular-beam epitaxy,"We analyze the structural and magnetic characteristics of (111)-oriented
+lutetium iron garnet (Lu$_3$Fe$_5$O$_{12}$) films grown by molecular-beam
+epitaxy, for films as thin as 2.8 nm. Thickness-dependent measurements of the
+in- and out-of-plane ferromagnetic resonance allow us to quantify the effects
+of two-magnon scattering, along with the surface anisotropy and the saturation
+magnetization. We achieve effective damping coefficients of $11.1(9) \times
+10^{-4}$ for 5.3 nm films and $32(3) \times 10^{-4}$ for 2.8 nm films, among
+the lowest values reported to date for any insulating ferrimagnetic sample of
+comparable thickness.",1609.04753v1
+2016-10-05,Higher-Harmonic Collective Modes in a Trapped Gas from Second-Order Hydrodynamics,"Utilizing a second-order hydrodynamics formalism, the dispersion relations
+for the frequencies and damping rates of collective oscillations as well as
+spatial structure of these modes up to the decapole oscillation in both two-
+and three- dimensional gas geometries are calculated. In addition to
+higher-order modes, the formalism also gives rise to purely damped
+""non-hydrodynamic"" modes. We calculate the amplitude of the various modes for
+both symmetric and asymmetric trap quenches, finding excellent agreement with
+an exact quantum mechanical calculation. We find that higher-order hydrodynamic
+modes are more sensitive to the value of shear viscosity, which may be of
+interest for the precision extraction of transport coefficients in Fermi gas
+systems.",1610.01611v2
+2016-12-06,Increased low-temperature damping in yttrium iron garnet thin films,"We report measurements of the frequency and temperature dependence of
+ferromagnetic resonance (FMR) for a 15-nm-thick yttrium iron garnet (YIG) film
+grown by off-axis sputtering. Although the FMR linewidth is narrow at room
+temperature (corresponding to a damping coefficient $\alpha$ = (9.0 $\pm$ 0.2)
+$\times 10^{-4}$), comparable to previous results for high-quality YIG films of
+similar thickness, the linewidth increases strongly at low temperatures, by a
+factor of almost 30. This increase cannot be explained as due to two-magnon
+scattering from defects at the sample interfaces. We argue that the increased
+low-temperature linewidth is due to impurity relaxation mechanisms that have
+been investigated previously in bulk YIG samples. We suggest that the
+low-temperature linewidth is a useful figure of merit to guide the optimization
+of thin-film growth protocols because it is a particularly sensitive indicator
+of impurities.",1612.01954v1
+2016-12-09,Slow motion for one-dimensional nonlinear damped hyperbolic Allen-Cahn systems,"We consider a nonlinear damped hyperbolic reaction-diffusion system in a
+bounded interval of the real line with homogeneous Neumann boundary conditions
+and we study the metastable dynamics of the solutions. Using an ""energy
+approach"" introduced by Bronsard and Kohn [CPAM 1990] to study slow motion for
+Allen-Cahn equation and improved by Grant [SIAM J. Math. Anal. 1995] in the
+study of Cahn-Morral systems, we improve and extend to the case of systems the
+results valid for the hyperbolic Allen-Cahn equation. In particular, we study
+the limiting behavior of the solutions as $\varepsilon\to0^+$, where
+$\varepsilon^2$ is the diffusion coefficient, and we prove existence and
+persistence of metastable states for a time
+$T_\varepsilon>\exp(A/\varepsilon)$. Such metastable states have a transition
+layer structure and the transition layers move with exponentially small
+velocity.",1612.03203v5
+2017-02-20,Resonant Scattering Characteristics of Homogeneous Dielectric Sphere,"In the present article the classical problem of electromagnetic scattering by
+a single homogeneous sphere is revisited. Main focus is the study of the
+scattering behavior as a function of the material contrast and the size
+parameters for all electric and magnetic resonances of a dielectric sphere.
+Specifically, the Pad\'e approximants are introduced and utilized as an
+alternative system expansion of the Mie coefficients. Low order Pad\'e
+approximants can give compact and physically insightful expressions for the
+scattering system and the enabled dynamic mechanisms. Higher order approximants
+are used for predicting accurately the resonant pole spectrum. These results
+are summarized into general pole formulae, covering up to fifth order magnetic
+and forth order electric resonances of a small dielectric sphere. Additionally,
+the connection between the radiative damping process and the resonant linewidth
+is investigated. The results obtained reveal the fundamental connection of the
+radiative damping mechanism with the maximum width occurring for each
+resonance. Finally, the suggested system ansatz is used for studying the
+resonant absorption maximum through a circuit-inspired perspective.",1702.05883v1
+2017-03-21,Numerical Range and Quadratic Numerical Range for Damped Systems,"We prove new enclosures for the spectrum of non-selfadjoint operator matrices
+associated with second order linear differential equations $\ddot{z}(t) + D
+\dot{z} (t) + A_0 z(t) = 0$ in a Hilbert space. Our main tool is the quadratic
+numerical range for which we establish the spectral inclusion property under
+weak assumptions on the operators involved; in particular, the damping operator
+only needs to be accretive and may have the same strength as $A_0$. By means of
+the quadratic numerical range, we establish tight spectral estimates in terms
+of the unbounded operator coefficients $A_0$ and $D$ which improve earlier
+results for sectorial and selfadjoint $D$; in contrast to numerical range
+bounds, our enclosures may even provide bounded imaginary part of the spectrum
+or a spectral free vertical strip. An application to small transverse
+oscillations of a horizontal pipe carrying a steady-state flow of an ideal
+incompressible fluid illustrates that our new bounds are explicit.",1703.07447v1
+2017-08-02,Global existence of solutions for semi-linear wave equation with scale-invariant damping and mass in exponentially weighted spaces,"In this paper we consider the following Cauchy problem for the semi-linear
+wave equation with scale-invariant dissipation and mass and power
+non-linearity: \begin{align}\label{CP abstract} \begin{cases} u_{tt}-\Delta
+u+\dfrac{\mu_1}{1+t} u_t+\dfrac{\mu_2^2}{(1+t)^2}u=|u|^p, \\ u(0,x)=u_0(x),
+\,\, u_t(0,x)=u_1(x), \end{cases}\tag{$\star$} \end{align} where $\mu_1,
+\mu_2^2$ are nonnegative constants and $p>1$. On the one hand we will prove a
+global (in time) existence result for \eqref{CP abstract} under suitable
+assumptions on the coefficients $\mu_1, \mu_2^2$ of the damping and the mass
+term and on the exponent $p$, assuming the smallness of data in exponentially
+weighted energy spaces. On the other hand a blow-up result for \eqref{CP
+abstract} is proved for values of $p$ below a certain threshold, provided that
+the data satisfy some integral sign conditions. Combining these results we find
+the critical exponent for \eqref{CP abstract} in all space dimensions under
+certain assumptions on $\mu_1$ and $\mu_2^2$. Moreover, since the global
+existence result is based on a contradiction argument, it will be shown firstly
+a local (in time) existence result.",1708.00738v1
+2017-11-11,Quantum Thermodynamics for Driven Dissipative Bosonic Systems,"We investigate two prototypical dissipative bosonic systems under slow
+driving and arbitrary system-bath coupling strength, recovering their dynamic
+evolution as well as the heat and work rates, and we verify that thermodynamic
+laws are respected. Specifically, we look at the damped harmonic oscillator and
+the damped two-level system. For the former, we study independently the slow
+time- dependent perturbation in the oscillator frequency and in the coupling
+strength. For the latter, we concentrate on the slow modulation of the energy
+gap between the two levels. Importantly, we are able to find the entropy
+production rates for each case without explicitly defining nonequilibrium
+extensions for the entropy functional. This analysis also permits the
+definition of phenomenological friction coefficients in terms of structural
+properties of the system-bath composite.",1711.04077v1
+2018-02-14,Motion of interfaces for a damped hyperbolic Allen-Cahn equation,"Consider the Allen-Cahn equation $u_t=\varepsilon^2\Delta u-F'(u)$, where $F$
+is a double well potential with wells of equal depth, located at $\pm1$. There
+are a lot of papers devoted to the study of the limiting behavior of the
+solutions as the diffusion coefficient $\varepsilon\to0^+$, and it is well
+known that, if the initial datum $u(\cdot,0)$ takes the values $+1$ and $-1$ in
+the regions $\Omega_+$ and $\Omega_-$, then the ""interface"" connecting
+$\Omega_+$ and $\Omega_-$ moves with normal velocity equal to the sum of its
+principal curvatures, i.e. the interface moves by mean curvature flow.
+  This paper concerns with the motion of the inteface for a damped hyperbolic
+Allen-Cahn equation, in a bounded domain of $\mathbb{R}^n$, for $n=2$ or $n=3$.
+In particular, we focus the attention on radially simmetric solutions, studying
+in detail the differences with the classic parabolic case, and we prove that,
+under appropriate assumptions on the initial data $u(\cdot,0)$ and
+$u_t(\cdot,0)$, the interface moves by mean curvature as $\varepsilon\to0^+$
+also in the hyperbolic framework.",1802.05038v1
+2018-04-01,Aggregated Momentum: Stability Through Passive Damping,"Momentum is a simple and widely used trick which allows gradient-based
+optimizers to pick up speed along low curvature directions. Its performance
+depends crucially on a damping coefficient $\beta$. Large $\beta$ values can
+potentially deliver much larger speedups, but are prone to oscillations and
+instability; hence one typically resorts to small values such as 0.5 or 0.9. We
+propose Aggregated Momentum (AggMo), a variant of momentum which combines
+multiple velocity vectors with different $\beta$ parameters. AggMo is trivial
+to implement, but significantly dampens oscillations, enabling it to remain
+stable even for aggressive $\beta$ values such as 0.999. We reinterpret
+Nesterov's accelerated gradient descent as a special case of AggMo and analyze
+rates of convergence for quadratic objectives. Empirically, we find that AggMo
+is a suitable drop-in replacement for other momentum methods, and frequently
+delivers faster convergence.",1804.00325v3
+2018-09-27,Non-equilibrium Quantum Langevin dynamics of orbital diamagnetic moment,"We investigate the time dependent orbital diamagnetic moment of a charged
+particle in a magnetic field in a viscous medium via the Quantum Langevin
+Equation. We study how the interplay between the cyclotron frequency and the
+viscous damping rate governs the dynamics of the orbital magnetic moment in the
+high temperature classical domain and the low temperature quantum domain for an
+Ohmic bath. These predictions can be tested via state of the art cold atom
+experiments with hybrid traps for ions and neutral atoms. We also study the
+effect of a confining potential on the dynamics of the magnetic moment. We
+obtain the expected Bohr Van Leeuwen limit in the high temperature, asymptotic
+time ($ \gamma t\longrightarrow \infty$, where $ \gamma $ is the viscous
+damping coefficient) limit.",1809.10370v1
+2018-12-10,Assessment of skin-friction-reduction techniques on a turbulent wing section,"The scope of the present project is to quantify the effects of uniform
+blowing and body-force damping on turbulent boundary layers subjected to a
+non-uniform adverse-pressure-gradient distribution. To this end, well-resolved
+large-eddy simulations are employed to describe the flow around the NACA4412
+airfoil at moderate Reynolds number 200, 000 based on freestream velocity and
+chord length. In the present paper we focus on uniform blowing and the
+conference presentation will include a comparison with body-force damping
+applied in the same region. The inner-scaled profiles of the mean velocity and
+of selected components of the Reynolds-stress tensor are examined and compared
+with the uncontrolled cases. It is known that uniform blowing and
+adverse-pressure gradients share some similarities in their effect on the
+boundary layers, and our results will show that these effects are not
+independent. The behaviour of the skin-friction coefficient is analyzed through
+the FIK decomposition, and the impact of this control strategy on the
+aerodynamic efficiency of the airfoil is discussed.",1812.03762v1
+2018-12-19,Rain Calms the Sea - The Impact of Entrained Air,"We propose a mechanism for the damping of short ocean gravity waves during
+rainstorms associated with the injection of air bubbles by rain drops. The
+mechanism is proposed as one of the possible explanations that ascribe to rain
+a calming effect on ocean surface waves. A model is developed that shows how
+wave attenuation increases with the presence of air bubbles in the upper
+reaches of the ocean. The model makes predictions of the effective wave
+dissipation coefficient, as a function of the volumetric ratio of air to water,
+as well as to the rainfall rate. The model predicts dissipation rates that are
+in line with experimental estimates of the effective wave damping rate.",1812.08200v2
+2019-01-10,Stability and Controllability results for a Timoshenko system,"In this paper, we study the indirect boundary stability and exact
+controllability of a one-dimensional Timoshenko system. In the first part of
+the paper, we consider the Timoshenko system with only one boundary fractional
+damping. We first show that the system is strongly stable but not uniformly
+stable. Hence, we look for a polynomial decay rate for smooth initial data.
+Using frequency domain arguments combined with the multiplier method, we prove
+that the energy decay rate depends on coefficients appearing in the PDE and on
+the order of the fractional damping. Moreover, under the equal speed
+propagation condition, we obtain the optimal polynomial energy decay rate. In
+the second part of this paper, we study the indirect boundary exact
+controllability of the Timoshenko system with mixed Dirichlet-Neumann boundary
+conditions and boundary control. Using non-harmonic analysis, we first
+establish a weak observability inequality, which depends on the ratio of the
+waves propagation speeds. Next, using the HUM method, we prove that the system
+is exactly controllable in appropriate spaces and that the control time can be
+small.",1901.03303v2
+2019-05-07,Integral representation formulae for the solution of a wave equation with time-dependent damping and mass in the scale-invariant case,"This paper is devoted to derive integral representation formulae for the
+solution of an inhomogeneous linear wave equation with time-dependent damping
+and mass terms, that are scale-invariant with respect to the so-called
+hyperbolic scaling. Yagdjian's integral transform approach is employed for this
+purpose. The main step in our argument consists in determining the kernel
+functions for the different integral terms, which are related to the source
+term and to initial data. We will start with the one dimensional case (in
+space). We point out that we may not apply in a straightforward way Duhamel's
+principle to deal with the source term since the coefficients of lower order
+terms make our model not invariant by time translation. On the contrary, we
+shall begin with the representation formula for the inhomogeneous equation with
+vanishing data by using a revised Duhamel's principle. Then, we will derive the
+representation of the solution in the homogeneous case with nontrivial data.
+After deriving the formula in the one dimensional case, the classical approach
+by spherical means is used in order to deal with the odd dimensional case.
+Finally, using the method of descent, the representation formula in the even
+dimensional case is proved.",1905.02408v1
+2019-05-20,Short time blow-up by negative mass term for semilinear wave equations with small data and scattering damping,"In this paper we study blow-up and lifespan estimate for solutions to the
+Cauchy problem with small data for semilinear wave equations with scattering
+damping and negative mass term. We show that the negative mass term will play a
+dominant role when the decay of its coefficients is not so fast, thus the
+solutions will blow up in a finite time. What is more, we establish a lifespan
+estimate from above which is much shorter than the usual one.",1905.08100v1
+2019-06-21,Control of eigenfunctions on surfaces of variable curvature,"We prove a microlocal lower bound on the mass of high energy eigenfunctions
+of the Laplacian on compact surfaces of negative curvature, and more generally
+on surfaces with Anosov geodesic flows. This implies controllability for the
+Schr\""odinger equation by any nonempty open set, and shows that every
+semiclassical measure has full support. We also prove exponential energy decay
+for solutions to the damped wave equation on such surfaces, for any nontrivial
+damping coefficient. These results extend previous works [arXiv:1705.05019],
+[arXiv:1712.02692], which considered the setting of surfaces of constant
+negative curvature.
+  The proofs use the strategy of [arXiv:1705.05019], [arXiv:1712.02692] and
+rely on the fractal uncertainty principle of [arXiv:1612.09040]. However, in
+the variable curvature case the stable/unstable foliations are not smooth, so
+we can no longer associate to these foliations a pseudodifferential calculus of
+the type used in [arXiv:1504.06589]. Instead, our argument uses Egorov's
+Theorem up to local Ehrenfest time and the hyperbolic parametrix of
+[arXiv:0706.3242], together with the $C^{1+}$ regularity of the stable/unstable
+foliations.",1906.08923v2
+2019-09-19,Blow-up for Strauss type wave equation with damping and potential,"We study a kind of nonlinear wave equations with damping and potential, whose
+coefficients are both critical in the sense of the scaling and depend only on
+the spatial variables. Based on the earlier works, one may think there are two
+kinds of blow-up phenomenons when the exponent of the nonlinear term is small.
+It also means there are two kinds of law to determine the critical exponent. In
+this paper, we obtain a blow-up result and get the estimate of the upper bound
+of the lifespan in critical and sub-critical cases. All of the results support
+such a conjecture, although for now, the existence part is still open.",1909.08885v3
+2019-12-10,Stability of traveling waves in a driven Frenkel-Kontorova model,"In this work we revisit a classical problem of traveling waves in a damped
+Frenkel-Kontorova lattice driven by a constant external force. We compute these
+solutions as fixed points of a nonlinear map and obtain the corresponding
+kinetic relation between the driving force and the velocity of the wave for
+different values of the damping coefficient. We show that the kinetic curve can
+become non-monotone at small velocities, due to resonances with linear modes,
+and also at large velocities where the kinetic relation becomes multivalued.
+Exploring the spectral stability of the obtained waveforms, we identify, at the
+level of numerical accuracy of our computations, a precise criterion for
+instability of the traveling wave solutions: monotonically decreasing portions
+of the kinetic curve always bear an unstable eigendirection. We discuss why the
+validity of this criterion in the {\it dissipative} setting is a rather
+remarkable feature offering connections to the Hamiltonian variant of the model
+and of lattice traveling waves more generally. Our stability results are
+corroborated by direct numerical simulations which also reveal the possible
+outcomes of dynamical instabilities.",1912.05052v2
+2020-06-10,Interpolation between Residual and Non-Residual Networks,"Although ordinary differential equations (ODEs) provide insights for
+designing network architectures, its relationship with the non-residual
+convolutional neural networks (CNNs) is still unclear. In this paper, we
+present a novel ODE model by adding a damping term. It can be shown that the
+proposed model can recover both a ResNet and a CNN by adjusting an
+interpolation coefficient. Therefore, the damped ODE model provides a unified
+framework for the interpretation of residual and non-residual networks. The
+Lyapunov analysis reveals better stability of the proposed model, and thus
+yields robustness improvement of the learned networks. Experiments on a number
+of image classification benchmarks show that the proposed model substantially
+improves the accuracy of ResNet and ResNeXt over the perturbed inputs from both
+stochastic noise and adversarial attack methods. Moreover, the loss landscape
+analysis demonstrates the improved robustness of our method along the attack
+direction.",2006.05749v4
+2020-06-24,The Complex Permeability of Split-Ring Resonator Arrays Measured at Microwave Frequencies,"We have measured the relative permeability of split-ring resonator (SRR)
+arrays used in metamaterials designed to have $\mu^\prime< 0$ over a narrow
+range of microwave frequencies. The SRR arrays were loaded into the bore of a
+loop-gap resonator (LGR) and reflection coefficient measurements were used to
+determine both the real and imaginary parts of the array's effective
+permeability. Data were collected as a function of array size and SRR spacing.
+The results were compared to those obtained from continuous extended split-ring
+resonators (ESRRs). The arrays of planar SRRs exhibited enhanced damping and a
+narrower range of frequencies with $\mu^\prime<0$ when compared to the ESRRs.
+The observed differences in damping, however, were diminished considerably when
+the array size was expanded from a one-dimensional array of $N$ SRRs to a
+$2\times 2\times N$ array. Our method can also be used to experimentally
+determine the effective permeability of other metamaterial designs.",2006.13861v1
+2020-12-28,Reliability optimization of friction-damped systems using nonlinear modes,"A novel probabilistic approach for the design of mechanical structures with
+friction interfaces is proposed. The objective function is defined as the
+probability that a specified performance measure of the forced vibration
+response is achieved subject to parameter uncertainties. The practicability of
+the approach regarding the extensive amount of required design evaluations is
+strictly related to the computational efficiency of the nonlinear dynamic
+analysis. Therefore, it is proposed to employ a recently developed parametric
+reduced order model (ROM) based on nonlinear modes of vibration, which can
+facilitate a decrease of the computational burden by several orders of
+magnitude. The approach was applied to a rotationally periodic assembly of a
+bladed disk with underplatform friction dampers. The robustness of the optimum
+damper design was significantly improved compared to the deterministic
+approach, taking into account uncertainties in the friction coefficient, the
+excitation level and the linear damping. Moreover, a scale invariance for
+piecewise linear contact constraints is proven, which can be very useful for
+the reduction of the numerical effort for the analysis of such systems.",2012.14466v1
+2021-01-25,A modified Kačanov iteration scheme with application to quasilinear diffusion models,"The classical Ka\v{c}anov scheme for the solution of nonlinear variational
+problems can be interpreted as a fixed point iteration method that updates a
+given approximation by solving a linear problem in each step. Based on this
+observation, we introduce a modified Ka\v{c}anov method, which allows for
+(adaptive) damping, and, thereby, to derive a new convergence analysis under
+more general assumptions and for a wider range of applications. For instance,
+in the specific context of quasilinear diffusion models, our new approach does
+no longer require a standard monotonicity condition on the nonlinear diffusion
+coefficient to hold. Moreover, we propose two different adaptive strategies for
+the practical selection of the damping parameters involved.",2101.10137v3
+2021-03-01,Dynamics of a ring of three unidirectionally coupled Duffing oscillators with time-dependent damping,"We study dynamics of a ring of three unidirectionally coupled double-well
+Duffing oscillators for three different values of the damping coefficient:
+fixed dumping, proportional to time, and inversely proportional to time. The
+dynamics in all cases is analyzed through time series, Fourier and Hilbert
+transforms, Poincar\'e sections, as well as bifurcation diagrams and Lyapunov
+exponents with respect to the coupling strength. In the first case, we observe
+a well-known route from a stable steady state to hyperchaos through Hopf
+bifurcation and a series of torus bifurcations, as the coupling strength is
+increased. In the second case, the system is highly dissipative and converges
+into one of stable equilibria. Finally, in the third case, transient toroidal
+hyperchaos takes place.",2103.01297v1
+2021-03-16,On an inverse problem of nonlinear imaging with fractional damping,"This paper considers the attenuated Westervelt equation in pressure
+formulation. The attenuation is by various models proposed in the literature
+and characterised by the inclusion of non-local operators that give power law
+damping as opposed to the exponential of classical models. The goal is the
+inverse problem of recovering a spatially dependent coefficient in the
+equation, the parameter of nonlinearity $\kappa(x)$, in what becomes a
+nonlinear hyperbolic equation with nonlocal terms. The overposed measured data
+is a time trace taken on a subset of the domain or its boundary. We shall show
+injectivity of the linearised map from $\kappa$ to the overposed data used to
+recover it and from this basis develop and analyse Newton-type schemes for its
+effective recovery.",2103.08965v1
+2021-04-22,Dissipation and fluctuations in elongated bosonic Josephson junctions,"We investigate the dynamics of bosonic atoms in elongated Josephson
+junctions. We find that these systems are characterized by an intrinsic
+coupling between the Josephson mode of macroscopic quantum tunneling and the
+sound modes. This coupling of Josephson and sound modes gives rise to a damped
+and stochastic Langevin dynamics for the Josephson degree of freedom. From a
+microscopic Lagrangian, we deduce and investigate the damping coefficient and
+the stochastic noise, which includes thermal and quantum fluctuations. Finally,
+we study the time evolution of relative-phase and population-imbalance
+fluctuations of the Josephson mode and their oscillating thermalization to
+equilibrium.",2104.11259v2
+2022-04-07,Pseudo Numerical Ranges and Spectral Enclosures,"We introduce the new concepts of pseu\-do numerical range for operator
+functions and families of sesquilinear forms as well as the pseu\-do block
+numerical range for $n \times n$ operator matrix functions. While these notions
+are new even in the bounded case, we cover operator polynomials with unbounded
+coefficients, unbounded holomorphic form families of type (a) and associated
+operator families of type (B). Our main results include spectral inclusion
+properties of pseudo numerical ranges and pseudo block numerical ranges. For
+diagonally dominant and off-diagonally dominant operator matrices they allow us
+to prove spectral enclosures in terms of the pseudo numerical ranges of Schur
+complements that no longer require dominance order $0$ and not even $<1$. As an
+application, we establish a new type of spectral bounds for linearly damped
+wave equations with possibly unbounded and/or singular damping.",2204.03584v1
+2022-04-14,Stability of Exponentially Damped Oscillations under Perturbations of the Mori-Chain,"There is an abundance of evidence that some relaxation dynamics, e.g.,
+exponential decays, are much more common in nature than others. Recently, there
+have been attempts to trace this dominance back to a certain stability of the
+prevalent dynamics versus generic Hamiltonian perturbations. In the paper at
+hand, we tackle this stability issue from yet another angle, namely in the
+framework of the recursion method. We investigate the behavior of various
+relaxation dynamics with respect to alterations of the so-called Lanczos
+coefficients. All considered scenarios are set up in order to comply with the
+""universal operator growth hypothesis"". Our numerical experiments suggest the
+existence of stability in a larger class of relaxation dynamics consisting of
+exponentially damped oscillations. Further, we propose a criterion to identify
+""pathological"" perturbations that lead to uncommon dynamics.",2204.06903v1
+2022-05-09,Mutual friction and diffusion of two-dimensional quantum vortices,"We present a microscopic open quantum systems theory of thermally-damped
+vortex motion in oblate atomic superfluids that includes previously neglected
+energy-damping interactions between superfluid and thermal atoms. This
+mechanism couples strongly to vortex core motion and causes dissipation of
+vortex energy due to mutual friction, as well as Brownian motion of vortices
+due to thermal fluctuations. We derive an analytic expression for the
+dimensionless mutual friction coefficient that gives excellent quantitative
+agreement with experimentally measured values, without any fitted parameters.
+Our work closes an existing two orders of magnitude gap between dissipation
+theory and experiments, previously bridged by fitted parameters, and provides a
+microscopic origin for the mutual friction and diffusion of quantized vortices
+in two-dimensional atomic superfluids.",2205.04065v2
+2022-05-12,Global existence and stability of subsonic time-periodic solution to the damped compressible Euler equations in a bounded domain,"In this paper, we consider the one-dimensional isentropic compressible Euler
+equations with source term $\beta(t,x)\rho|u|^{\alpha}u$ in a bounded domain,
+which can be used to describe gas transmission in a nozzle.~The model is
+imposed a subsonic time-periodic boundary condition.~Our main results reveal
+that the time-periodic boundary can trigger an unique subsonic time-periodic
+smooth solution and this unique periodic solution is stable under small
+perturbations on initial and boundary data.~To get the existence of subsonic
+time-periodic solution, we use the linear iterative skill and transfer the
+boundary value problem into two initial value ones by using the hyperbolic
+property of the system. Then the corresponding linearized system can be
+decoupled.~The uniqueness is a direct by-product of the stability. There is no
+small assumptions on the damping coefficient.",2205.05858v2
+2022-09-11,Approximation of Algebraic Riccati Equations with Generators of Noncompact Semigroups,"In this work, we demonstrate that the Bochner integral representation of the
+Algebraic Riccati Equations (ARE) are well-posed without any compactness
+assumptions on the coefficient and semigroup operators. From this result, we
+then are able to determine that, under some assumptions, the solution to the
+Galerkin approximations to these equations are convergent to the infinite
+dimensional solution. Going further, we apply this general result to
+demonstrate that the finite element approximation to the ARE are optimal for
+weakly damped wave semigroup processes in the $H^1(\Omega) \times L^2(\Omega)$
+norm. Optimal convergence rates of the functional gain for a weakly damped wave
+optimal control system in both the $H^1(\Omega) \times L^2(\Omega)$ and
+$L^2(\Omega)\times L^2(\Omega)$ norms are demonstrated in the numerical
+examples.",2209.04769v5
+2022-11-18,"Accelerated gradient methods with strong convergence to the minimum norm minimizer: a dynamic approach combining time scaling, averaging, and Tikhonov regularization","In a Hilbert framework, for convex differentiable optimization, we consider
+accelerated gradient methods obtained by combining temporal scaling and
+averaging techniques with Tikhonov regularization. We start from the continuous
+steepest descent dynamic with an additional Tikhonov regularization term whose
+coefficient vanishes asymptotically. We provide an extensive Lyapunov analysis
+of this first-order evolution equation. Then we apply to this dynamic the
+method of time scaling and averaging recently introduced by Attouch, Bot and
+Nguyen. We thus obtain an inertial dynamic which involves viscous damping
+associated with Nesterov's method, implicit Hessian damping and Tikhonov
+regularization. Under an appropriate setting of the parameters, just using
+Jensen's inequality, without the need for another Lyapunov analysis, we show
+that the trajectories have at the same time several remarkable properties: they
+provide a rapid convergence of values, fast convergence of the gradients to
+zero, and strong convergence to the minimum norm minimizer. These results
+complete and improve the previous results obtained by the authors.",2211.10140v1
+2022-12-21,Global existence and Blow-up for the 1D damped compressible Euler equations with time and space dependent perturbation,"In this paper, we consider the 1D Euler equation with time and space
+dependent damping term $-a(t,x)v$. It has long been known that when $a(t,x)$ is
+a positive constant or $0$, the solution exists globally in time or blows up in
+finite time, respectively. We prove that those results are invariant with
+respect to time and space dependent perturbations. We suppose that the
+coefficient $a$ satisfies the following condition $$ |a(t,x)- \mu_0| \leq
+a_1(t) + a_2 (x), $$ where $\mu_0 \geq 0$ and $a_1$ and $a_2$ are integrable
+functions with $t$ and $x$. Under this condition, we show the global existence
+and the blow-up with small initial data, when $\mu_0 >0$ and $\mu=0$
+respectively.",2212.11072v2
+2023-07-19,A spin-rotation mechanism of Einstein-de Haas effect based on a ferromagnetic disk,"Spin-rotation coupling (SRC) is a fundamental phenomenon that connects
+electronic spins with the rotational motion of a medium. We elucidate the
+Einstein-de Haas (EdH) effect and its inverse with SRC as the microscopic
+mechanism using the dynamic spin-lattice equations derived by elasticity theory
+and Lagrangian formalism. By applying the coupling equations to an iron disk in
+a magnetic field, we exhibit the transfer of angular momentum and energy
+between spins and lattice, with or without damping. The timescale of the
+angular momentum transfer from spins to the entire lattice is estimated by our
+theory to be on the order of 0.01 ns, for the disk with a radius of 100 nm.
+Moreover, we discover a linear relationship between the magnetic field strength
+and the rotation frequency, which is also enhanced by a higher ratio of Young's
+modulus to Poisson's coefficient. In the presence of damping, we notice that
+the spin-lattice relaxation time is nearly inversely proportional to the
+magnetic field. Our explorations will contribute to a better understanding of
+the EdH effect and provide valuable insights for magneto-mechanical
+manufacturing.",2307.10390v1
+2023-08-05,The isometric immersion of surfaces with finite total curvature,"In this paper, we study the smooth isometric immersion of a complete simply
+connected surface with a negative Gauss curvature in the three-dimensional
+Euclidean space. For a surface with a finite total Gauss curvature and
+appropriate oscillations of the Gauss curvature, we prove the global existence
+of a smooth solution to the Gauss-Codazzi system and thus establish a global
+smooth isometric immersion of the surface into the three-dimensional Euclidean
+space. Based on a crucial observation that some linear combinations of the
+Riemann invariants decay faster than others, we reformulate the Gauss-Codazzi
+system as a symmetric hyperbolic system with a partial damping. Such a damping
+effect and an energy approach permit us to derive global decay estimates and
+meanwhile control the non-integrable coefficients of nonlinear terms.",2308.02832v2
+2023-08-30,Stochastic Thermodynamics of Brownian motion in Temperature Gradient,"We study stochastic thermodynamics of a Brownian particle which is subjected
+to a temperature gradient and is confined by an external potential. We first
+formulate an over-damped Ito-Langevin theory in terms of local temperature,
+friction coefficient, and steady state distribution, all of which are
+experimentally measurable. We then study the associated stochastic
+thermodynamics theory. We analyze the excess entropy production (EP) both at
+trajectory level and at ensemble level, and derive the Clausius inequality as
+well as the transient fluctuation theorem (FT). We also use molecular dynamics
+to simulate a Brownian particle inside a Lennard-Jones fluid and verify the FT.
+Remarkably we find that the FT remains valid even in the under-damped regime.
+We explain the possible mechanism underlying this surprising result.",2308.15764v3
+2023-12-27,Universal orbital and magnetic structures in infinite-layer nickelates,"We conducted a comparative study of the rare-earth infinite-layer nickelates
+films, RNiO2 (R = La, Pr, and Nd) using resonant inelastic X-ray scattering
+(RIXS). We found that the gross features of the orbital configurations are
+essentially the same, with minor variations in the detailed hybridization. For
+low-energy excitations, we unambiguously confirm the presence of damped
+magnetic excitations in all three compounds. By fitting to a linear spin-wave
+theory, comparable spin exchange coupling strengths and damping coefficients
+are extracted, indicating a universal magnetic structure in the infinite-layer
+nickelates. Interestingly, while signatures of a charge order are observed in
+LaNiO2 in the quasi-elastic region of the RIXS spectrum, it is absent in NdNiO2
+and PrNiO2. This prompts further investigation into the universality and the
+origins of charge order within the infinite-layer inickelates.",2312.16444v1
+2005-07-28,Transverse spin waves in isotropic ferromagnets,"The comparison of transverse spin wave spectra and its attenuation in
+Heisenberg ferromagnet and in ferromagnetic Fermi liquid as well in polarized
+Fermi liquid is undertaken. The transverse spin waves frequency in polarized
+paramagnetic Fermi liquid as well in a Fermi liquid with spontaneous
+magnetization is found to be proportional to the square of the wave vector with
+complex diffusion coefficient such that the damping has a finite value
+proportional to the scattering rate of quasiparticles at T=0.
+  This behavior of polarized Fermi liquid contrasts with the behavior of
+Heisenberg ferromagnet in hydrodynamic regime where the transverse spin wave
+attenuation appears in terms proportional to the wave vector in fourth power.
+  The reactive part of diffusion coefficient in paramagnetic state at T=0
+proves to be inversely proportional to magnetization whereas in ferromagnetic
+state it is directly proportional to magnetization. The dissipative part of
+diffusion coefficient at T=0 in paramagnetic state is polarization independent,
+whereas in ferromagnetic state it is proportional to square of magnetization.
+Moreover, the spin wave spectrum in ferromagnetic Fermi liquid proves to be
+unstable that demonstrates the difficulty of the Fermi liquid description of
+itinerant ferromagnetism.",0507676v1
+1998-10-22,Quantifying excitations of quasinormal mode systems,"Computations of the strong field generation of gravitational waves by black
+hole processes produce waveforms that are dominated by quasinormal (QN)
+ringing, a damped oscillation characteristic of the black hole. We describe
+here the mathematical problem of quantifying the QN content of the waveforms
+generated. This is done in several steps: (i) We develop the mathematics of QN
+systems that are complete (in a sense to be defined) and show that there is a
+quantity, the ``excitation coefficient,'' that appears to have the properties
+needed to quantify QN content. (ii) We show that incomplete systems can (at
+least sometimes) be converted to physically equivalent complete systems. Most
+notably, we give a rigorous proof of completeness for a specific modified model
+problem. (iii) We evaluate the excitation coefficient for the model problem,
+and demonstrate that the excitation coefficient is of limited utility. We
+finish by discussing the general question of quantification of QN excitations,
+and offer a few speculations about unavoidable differences between normal mode
+and QN systems.",9810074v1
+2007-04-09,Bulk viscosity of superfluid neutron stars,"The hydrodynamics, describing dynamical effects in superfluid neutron stars,
+essentially differs from the standard one-fluid hydrodynamics. In particular,
+we have four bulk viscosity coefficients in the theory instead of one. In this
+paper we calculate these coefficients, for the first time, assuming they are
+due to non-equilibrium beta-processes (such as modified or direct Urca
+process). The results of our analysis are used to estimate characteristic
+damping times of sound waves in superfluid neutron stars. It is demonstrated
+that all four bulk viscosity coefficients lead to comparable dissipation of
+sound waves and should be considered on the same footing.",0704.1071v2
+2008-07-28,Enhancement of thermal transport in the degenerate periodic Anderson model,"The low-temperature transport coefficients of the degenerate periodic SU(N)
+Anderson model are calculated in the limit of infinite correlation between {\it
+f} electrons, within the framework of dynamical mean-field theory. We establish
+the Fermi liquid (FL) laws in the clean limit, taking into account the
+quasiparticle damping. The latter yields a reduced value of the Lorenz number
+in the Wiedemann-Franz law. Our results indicate that the renormalization of
+the thermal conductivity and of the Seebeck coefficient can lead to a
+substantial enhancement of the electronic thermoelectric figure-of-merit at low
+temperature.
+  Using the FL laws we discuss the low-temperature anomalies that show up in
+the electrical resistance of the intermetallic compounds with Cerium and
+Ytterbium ions, when studied as a function of pressure.
+  Our calculations explain the sharp maximum of the coefficient of the
+$T^2$-term of the electrical resistance and the rapid variation of residual
+resistance found in a number of Ce and Yb intermetallics at some critical
+pressure.",0807.4385v2
+2012-06-09,Non linearities in the harmonic spectrum of heavy ion collisions with ideal and viscous hydrodynamics,"We determine the non-linear hydrodynamic response to geometrical fluctuations
+in heavy ion collisions using ideal and viscous hydrodynamics. This response is
+characterized with a set of non-linear response coefficients that determine,
+for example, the $v_5$ that is produced by an $\epsilon_2$ and an $\epsilon_3$.
+We analyze how viscosity damps both the linear and non-linear response
+coefficients, and provide an analytical estimate that qualitatively explains
+most of the trends observed in more complete simulations. Subsequently, we use
+these nonlinear response coefficients to determine the linear and non-linear
+contributions to $v_1$, $v_4$ and $v_5$. For viscous hydrodynamics the
+nonlinear contribution is dominant for $v_4$, $v_5$ and higher harmonics. For
+$v_1$, the nonlinear response constitutes an important $\sim 25%$ correction in
+mid-central collisions. The nonlinear response is also analyzed as a function
+of transverse momentum for $v_1$, $v_4$ and $v_5$. Finally, recent measurements
+of correlations between event-planes of different harmonic orders are discussed
+in the context of non-linear response.",1206.1905v2
+2014-10-05,Finite-time stabilization of a network of strings,"We investigate the finite-time stabilization of a tree-shaped network of
+strings. Transparent boundary conditions are applied at all the external nodes.
+At any internal node, in addition to the usual continuity conditions, a
+modified Kirchhoff law incorporating a damping term $\alpha u_t$ with a
+coefficient $\alpha$ that may depend on the node is considered. We show that
+for a convenient choice of the sequence of coefficients $\alpha$, any solution
+of the wave equation on the network becomes constant after a finite time. The
+condition on the coefficients proves to be sharp at least for a star-shaped
+tree. Similar results are derived when we replace the transparent boundary
+condition by the Dirichlet (resp. Neumann) boundary condition at one external
+node.",1410.1122v1
+2014-11-03,Experimental Demonstration of the Co-existence of the Spin Hall and Rashba Effects in beta-Tantalum/Ferromagnet Bilayers,"We have measured the spin torques of beta-Tantalum / Co20Fe60B20 bilayers
+versus Ta thickness at room temperature using an FMR technique. The spin Hall
+coefficient was calculated both from the observed change in damping coefficient
+of the ferromagnet with Ta thickness, and from the ratio of the symmetric and
+anti-symmetric components of the FMR signal. Results from these two methods
+yielded values for the spin Hall coefficient of -0.090+/-0.005 and
+-0.11+/-0.01, respectively. We have also identified a significant out-of-plane
+spin torque originating from Ta, which is constant with Ta thickness. We
+ascribe this to an interface spin orbit coupling, or Rashba effect, due to the
+strength and constancy of the torque with Ta thickness. From fitting measured
+data to a model including interface spin orbit coupling, we have determined the
+spin diffusion length for beta-Tantalum to be ~2.5 nm.",1411.0601v1
+2017-11-05,An entropy production based method for determining the position diffusion's coefficient of a quantum Brownian motion,"Quantum Brownian motion of a harmonic oscillator in the Markovian
+approximation is described by the respective Caldeira-Leggett master equation.
+This master equation can be brought into Lindblad form by adding a position
+diffusion term to it. The coefficient of this term is either customarily taken
+to be the lower bound dictated by the Dekker inequality or determined by more
+detailed derivations on the linearly damped quantum harmonic oscillator. In
+this paper, we explore the theoretical possibilities of determining the
+position diffusion term's coefficient by analyzing the entropy production of
+the master equation.",1711.01642v2
+2019-03-25,Bouncing behavior and dissipative characterization of a chain-filled granular damper,"We have experimentally investigated the bouncing behavior and damping
+performance of a container partially filled with granular chains, namely a
+chain-filled damper. The motion of the chain-filled damper, recorded by a
+particle tracing technology, demonstrates that the granular chains can
+efficiently absorb the collisional energy of the damper. We extract both the
+restitution coefficient of the first collision and the total flight time to
+characterize the dissipation ability of the damper. Two containers and three
+types of granular chains, different in size, stiffness and restitution
+coefficient, are used to examine the experimental results. We find that the
+restitution coefficient of the first collision of a single-chain-filled damper
+can linearly tend to vanish with increasing the chain length and obtain a
+minimum filling mass required to cease the container at the first collision (no
+rebound). When the strong impact occurs, the collisional absorption efficiency
+of a chain-filled damper is superior to a monodisperse-particle-filled damper.
+Furthermore, the longer the chains are, the better the dissipative effect is.",1903.10329v1
+2020-02-06,Measurement of resistance coefficients of pendulum motion with balls of various sizes,"In order to obtain the damping and resistance coefficients of a pendulum, we
+constructed an optical system containing a photogate for measuring the speed of
+the pendulum at the lowest point of motion. The photogate consisted of a
+photoresistor, a laser, a mechanical body, and a pendulum ball. A 3D printer
+was used to produce the mechanical body and pendulum balls of various sizes.
+Furthermore, we used Arduino to automate measurement of the speed at the lowest
+point of motion and increase the precision. We found that the resistance
+coefficient was proportional to the size of the balls, regardless of the ball
+mass, in agreement with the drag equation for a small Reynolds number.",2002.03796v1
+2022-01-25,Kinetics of hydrodynamic pions in chiral perturbation theory,"We determine the kinetic coefficients of ultrasoft pions using chiral
+perturbation theory at finite temperature close to the chiral limit. This is
+used to compute the axial charge diffusion and damping coefficients in the
+hydrodynamic effective theory for these pion waves. We show that to provide a
+leading order answer for these coefficients one needs to explore the dynamics
+of hard, soft, and ultrasoft pion modes, which are represented microscopically
+by the appropriate kinetic and hydrodynamic descriptions..",2201.10495v2
+2022-09-21,Cross effects in spin hydrodynamics: A revisit Entropy analysis and statistical operator,"We revisit the construction of first-order spin hydrodynamics and find that
+the constitution relations receive the corrections from the cross effects
+resulting from spin-orbit coupling. Starting from a routine entropy analysis,
+we show how to identify cross effects and new cross transport coefficients from
+the second law of thermodynamics. Interestingly, the conventional transport
+coefficient heat conductivity $\kappa$ is bounded from below by the product of
+cross transport coefficients, which means the threshold of heat conduction is
+changed. With recourse to Zubarev's non-equilibrium statistical operator, we
+reproduce the construction of first-order spin hydrodynamics and identification
+of cross effects in a more rigorous way. By seeking the dispersion relations of
+normal modes, we find that these cross effects suppress the attenuation of
+sound modes and heat mode appearing in conventional hydrodynamics and also have
+impacts on the damping of non-hydrodynamic spin modes.",2209.10979v2
+2024-02-14,Global existence and long time behavior of solutions to some Oldroyd type models in hybrid Besov spaces,"In this paper, we deal with some Oldroyd type models, which describe
+incompressible viscoelastic fluids. There are 3 parameters in these models: the
+viscous coefficient of fluid $\nu_{1}$, the viscous coefficient of the elastic
+part of the stress tensor $\nu_{2}$, and the damping coefficient of the elastic
+part of the stress tensor $\alpha$. In this paper, we assume at least one of
+the parameters is zero: $(\nu_{1}, \nu_{2},\alpha)=(+,0,+), (+,0,0), (0,+,+),
+(0,+,0), (0,0,+)$ and prove the global existence of unique solutions to all
+these 5 cases in the framework of hybrid Besov spaces. We also derive decay
+rates of the solutions except for the case $(\nu_{1}, \nu_{2},\alpha)=(+,0,0)$.
+To the best of our knowledge, decay rates in this paper are the first results
+in this framework, and can improve some previous works.",2402.09175v1
+2012-06-14,On the Interpretation of the Foundations of Quantum Mechanics,"This study discusses the quantum behavior of a particle, which is controlled
+by fluctuations in the physical space-time (ST) variables, rather than provides
+a novel interpretation of quantum theory. The fluctuations, i.e.,
+inhomogeneities in a homogeneous phase ST, are prescribed by their probability.
+They determine the reciprocal space and correlate with the correlation entropy
+different from zero. Alongside with the minimum entropy, action, and the
+presence of the Winn-Ehrenfest adiabatic invariant (AI), the fluctuations
+require the Gilbert information (probabilistic) space linking the physical and
+the reciprocal ST. Physical quantities in the information space are represented
+by linear Hermitian operators, which is due to the entropy production in the
+presence of an AI. Evolution of a quantum system is described by the wave
+functions having the meaning of information concerning all virtually possible
+states of a quantum particle. The wave functions are the solutions to the
+Schrodinger equation and represent a navigation 'roadmap' for the particle to
+follow. A quantum system is in fact a classical Hamiltonian system in the space
+of coefficients of the wave function decomposition with respect to the operator
+eigenfunctions. It is the linearity and the Hermitian nature of the operators
+which determine the trajectory and the superposition principle in case of the
+wave behavior of fluctuations. The uncertainty principle, reflects correlation
+of the fluctuations and, hence, their nonlocality. This study discusses the
+wave function phase, the Berry phase and its relationship to quantization,
+discriminability of states and macroscopic quantum effects caused by
+localization of the particle, followed by a possible entropy change during its
+transition into a new thermodynamic state.",1206.2998v1
+2019-11-15,A geometric look at MHD and the Braginsky dynamo,"This paper considers magnetohydrodynamics (MHD) and some of its applications
+from the perspective of differential geometry, considering the dynamics of an
+ideal fluid flow and magnetic field on a general three-dimensional manifold,
+equipped with a metric and an induced volume form. The benefit of this level of
+abstraction is that it clarifies basic aspects of fluid dynamics such as how
+certain quantities are transported, how they transform under the action of
+mappings (for example the flow map between Lagrangian labels and Eulerian
+positions), how conservation laws arise, and the origin of certain
+approximations that preserve the mathematical structure of classical mechanics.
+First, the governing equations for ideal MHD are derived in a general setting
+by means of an action principle, and making use of Lie derivatives. The way in
+which these equations transform under a pull back, by the map taking the
+position of a fluid parcel to a background location, is detailed. This is then
+used to parameterise Alfv\'en waves using concepts of pseudomomentum and
+pseudofield, in parallel with the development of Generalised Lagrangian Mean
+theory in hydrodynamics. Finally non-ideal MHD is considered with a sketch of
+the development of the Braginsky $\alpha\omega$-dynamo in a general setting.
+Expressions for the $\alpha$-tensor are obtained, including a novel geometric
+formulation in terms of connection coefficients, and related to formulae found
+elsewhere in the literature.",1911.06592v2
+2020-09-18,Information- and Coding-Theoretic Analysis of the RLWE Channel,"Several cryptosystems based on the \emph{Ring Learning with Errors} (RLWE)
+problem have been proposed within the NIST post-quantum cryptography
+standardization process, e.g., NewHope. Furthermore, there are systems like
+Kyber which are based on the closely related MLWE assumption. Both previously
+mentioned schemes result in a non-zero decryption failure rate (DFR). The
+combination of encryption and decryption for these kinds of algorithms can be
+interpreted as data transmission over a noisy channel. To the best of our
+knowledge this paper is the first work that analyzes the capacity of this
+channel. We show how to modify the encryption schemes such that the input
+alphabets of the corresponding channels are increased. In particular, we
+present lower bounds on their capacities which show that the transmission rate
+can be significantly increased compared to standard proposals in the
+literature. Furthermore, under the common assumption of stochastically
+independent coefficient failures, we give lower bounds on achievable rates
+based on both the Gilbert-Varshamov bound and concrete code constructions using
+BCH codes. By means of our constructions, we can either increase the total
+bitrate (by a factor of $1.84$ for Kyber and by factor of $7$ for NewHope)
+while guaranteeing the same DFR or for the same bitrate, we can significantly
+reduce the DFR for all schemes considered in this work (e.g., for NewHope from
+$2^{-216}$ to $2^{-12769}$).",2009.08681v3
+2021-05-18,Magnetic flux structuring of the quiet Sun internetwork. Center-to-limb analysis of solar-cycle variations,"It is now well established that the quiet Sun contains in total more magnetic
+flux than active regions and represents an important reservoir of magnetic
+energy. But the nature and evolution of these fields remain largely unknown.
+  We investigate the solar-cycle and center-to-limb variations of magnetic-flux
+structures at small scales in internetwork regions of the quiet Sun.
+  We used Hinode SOT/SP data from the irradiance program between 2008 and 2016.
+Maps of the magnetic-flux density are derived from the center-of gravity method
+applied to the FeI 630.15 nm and FeI 630.25 nm lines. To correct the maps from
+the instrumental smearing, we applied a deconvolution method based on a
+principal component analysis of the line profiles and on a Richardson-Lucy
+deconvolution of their coefficients. We then performed a spectral analysis of
+the spatial fluctuations of the magnetic-flux density in 10'' x 10''
+internetwork regions spanning a wide range of latitudes.
+  At low and mid latitudes the power spectra do not vary significantly with the
+solar cycle. However at solar maximum for one scan in the activity belt showing
+an enhanced network, a marginal increase in the power of the magnetic
+fluctuations is observed at granular and larger scales in the internetwork. At
+high latitudes, we observe variations at granular and larger scales where the
+power decreases at solar maximum. At all the latitudes the power of the
+magnetic fluctuations at scales smaller than 0.5''remain constant throughout
+the solar cycle.
+  Our results favor a small-scale dynamo that operates in the internetwork, but
+they show that the global dynamo also contributes to the internetwork fields.",2105.08657v1
+2021-07-24,Dual-Attention Enhanced BDense-UNet for Liver Lesion Segmentation,"In this work, we propose a new segmentation network by integrating DenseUNet
+and bidirectional LSTM together with attention mechanism, termed as
+DA-BDense-UNet. DenseUNet allows learning enough diverse features and enhancing
+the representative power of networks by regulating the information flow.
+Bidirectional LSTM is responsible to explore the relationships between the
+encoded features and the up-sampled features in the encoding and decoding
+paths. Meanwhile, we introduce attention gates (AG) into DenseUNet to diminish
+responses of unrelated background regions and magnify responses of salient
+regions progressively. Besides, the attention in bidirectional LSTM takes into
+account the contribution differences of the encoded features and the up-sampled
+features in segmentation improvement, which can in turn adjust proper weights
+for these two kinds of features. We conduct experiments on liver CT image data
+sets collected from multiple hospitals by comparing them with state-of-the-art
+segmentation models. Experimental results indicate that our proposed method
+DA-BDense-UNet has achieved comparative performance in terms of dice
+coefficient, which demonstrates its effectiveness.",2107.11645v1
+2023-12-03,Heisenberg machines with programmable spin-circuits,"We show that we can harness two recent experimental developments to build a
+compact hardware emulator for the classical Heisenberg model in statistical
+physics. The first is the demonstration of spin-diffusion lengths in excess of
+microns in graphene even at room temperature. The second is the demonstration
+of low barrier magnets (LBMs) whose magnetization can fluctuate rapidly even at
+sub-nanosecond rates. Using experimentally benchmarked circuit models, we show
+that an array of LBMs driven by an external current source has a steady-state
+distribution corresponding to a classical system with an energy function of the
+form $E = -1/2\sum_{i,j} J_{ij} (\hat{m}_i \cdot \hat{m}_j$). This may seem
+surprising for a non-equilibrium system but we show that it can be justified by
+a Lyapunov function corresponding to a system of coupled
+Landau-Lifshitz-Gilbert (LLG) equations. The Lyapunov function we construct
+describes LBMs interacting through the spin currents they inject into the spin
+neutral substrate. We suggest ways to tune the coupling coefficients $J_{ij}$
+so that it can be used as a hardware solver for optimization problems involving
+continuous variables represented by vector magnetizations, similar to the role
+of the Ising model in solving optimization problems with binary variables.
+Finally, we implement a Heisenberg AND gate based on a network of three coupled
+stochastic LLG equations, illustrating the concept of probabilistic computing
+with a programmable Heisenberg model.",2312.01477v1
+2024-02-19,Density estimation for elliptic PDE with random input by preintegration and quasi-Monte Carlo methods,"In this paper, we apply quasi-Monte Carlo (QMC) methods with an initial
+preintegration step to estimate cumulative distribution functions and
+probability density functions in uncertainty quantification (UQ). The
+distribution and density functions correspond to a quantity of interest
+involving the solution to an elliptic partial differential equation (PDE) with
+a lognormally distributed coefficient and a normally distributed source term.
+There is extensive previous work on using QMC to compute expected values in UQ,
+which have proven very successful in tackling a range of different PDE
+problems. However, the use of QMC for density estimation applied to UQ problems
+will be explored here for the first time. Density estimation presents a more
+difficult challenge compared to computing the expected value due to
+discontinuities present in the integral formulations of both the distribution
+and density. Our strategy is to use preintegration to eliminate the
+discontinuity by integrating out a carefully selected random parameter, so that
+QMC can be used to approximate the remaining integral. First, we establish
+regularity results for the PDE quantity of interest that are required for
+smoothing by preintegration to be effective. We then show that an $N$-point
+lattice rule can be constructed for the integrands corresponding to the
+distribution and density, such that after preintegration the QMC error is of
+order $\mathcal{O}(N^{-1+\epsilon})$ for arbitrarily small $\epsilon>0$. This
+is the same rate achieved for computing the expected value of the quantity of
+interest. Numerical results are presented to reaffirm our theory.",2402.11807v1
+2004-11-02,Spurious contribution to CR scattering calculations,"The quasilinear theory for cosmic ray propagation is a well known and widely
+accepted theory. In this paper, we discuss the different contributions to the
+pitch-angle Fokker-Planck coefficient from large and small scales for slab
+geometry using the damping model of dynamical turbulence. These examinations
+will give us a hint on the limitation range where quasilinear approximation is
+a good approximation.",0411074v1
+2006-01-16,Bistability in Interstellar Gas-Phase Chemistry,"We present an analysis of ""bistability"" in gas-phase chemical models of dark
+interstellar clouds. We identify the chemical mechanisms that allow high- and
+low-ionization solutions to the chemical rate-equations to coexist. We derive
+simple analytic scaling relations for the gas densities and ionization rates
+for which the chemistry becomes bistable. We explain why bistability is
+sensitive to the H3+ dissociative recombination rate coefficient, and why it is
+damped by gas-grain neutralization.",0601323v1
+1995-03-17,Motion of heavy particles coupled to fermionic and bosonic environments in one dimension,"Making use of a simple unitary transformation we change the hamiltonian of a
+particle coupled to an one dimensional gas of bosons or fermions to a new form
+from which the many body degrees of freedom can be easily traced out. The
+effective dynamics of the particle allows us to compute its damping constant in
+terms of the reflection coefficient of the interaction potential and the
+occupation number of the environmental particles. We apply our results to a
+delta repulsive potential.",9503089v2
+1997-06-06,Dynamics of viscous amphiphilic films supported by elastic solid substrates,"The dynamics of amphiphilic films deposited on a solid surface is analyzed
+for the case when shear oscillations of the solid surface are excited. The two
+cases of surface- and bulk shear waves are studied with film exposed to gas or
+to a liquid. By solving the corresponding dispersion equation and the wave
+equation while maintaining the energy balance we are able to connect the
+surface density and the shear viscocity of a fluid amphiphilic overlayer with
+experimentally accessible damping coefficients, phase velocity, dissipation
+factor and resonant frequency shifts of shear waves.",9706058v1
+1997-09-30,AC transport with reservoirs of finite width,"The linear response conductance coefficients are calculated in the scattering
+approach at finite frequency, damping and magnetic field for a microstructure
+in which the reservoirs are modeled as quantum wire leads of infinite length
+but finite width. Independently of frequency, inelastic scattering causes
+subbands with large group velocity to contribute more strongly to the
+conductance than channels of comparable transmission but slower propagation. At
+finite frequency and magnetic fields, additional correction terms appear, some
+of which are sensitive to the phase of the S matrix.",9709332v2
+1999-12-08,Thermodynamical fluctuations and photo-thermal shot noise in gravitational wave antennae,"Thermodynamical fluctuations of temperature in mirrors of gravitational wave
+antennae are transformed through thermal expansion coefficient into additional
+noise. This source of noise, which may also be interpreted as fluctuations due
+to thermoelastic damping, may not be neglected and leads to the necessity to
+reexamine the choice of materials for the mirrors. Additional source of noise
+are fluctuations of the mirrors' surfaces caused by optical power absorbed in
+dielectrical reflective layers.",9912139v1
+2001-02-26,Relaxation time of weakly interacting superparamagnets,"The relaxation time of weakly interacting classical spins is calculated by
+introducing the averages of the local dipolar field, obtained by thermodynamic
+perturbation theory, in a rigorous expression for the single-spin
+thermoactivation rate in a weak but arbitrarily oriented field. At low
+temperatures the non-trivial dependence of the superparamagnetic blocking on
+the damping coefficient, numerically found by Berkov and Gorn, is reproduced by
+our model and interpreted in terms of the deviations from uniaxial anisotropy
+associated to the transversal component of the dipolar field acting on each
+spin.",0102472v1
+2001-08-11,Spin dynamics from time-dependent spin density-functional theory,"We derive the spin-wave dynamics of a magnetic material from the
+time-dependent spin density functional theory in the linear response regime.
+The equation of motion for the magnetization includes, besides the static spin
+stiffness, a ""Berry curvature"" correction and a damping term. A gradient
+expansion scheme based on the homogeneous spin-polarized electron gas is
+proposed for the latter two quantities, and the first few coefficients of the
+expansion are calculated to second order in the Coulomb interaction.",0108193v1
+2006-02-01,Special frequencies in reflection spectra of Bragg multiple quantum well structures,"We have studied theoretically optical reflection spectra from the Bragg
+multiple quantum well structures. We give an analytical explanation of the
+presence of two special frequencies in the spectra at which the reflection
+coefficient weakly depends on the quantum well number. The influence of the
+exciton nonradiative damping on the reflection spectra has been analyzed. It
+has been shown that allowance for the dielectric contrast gives rise to the
+third special frequency at which the contributions to the reflectivity related
+to the dielectric contrast and the exciton resonance mutually compensate one
+another.",0602013v1
+2007-02-05,Diffusion in Modulated Media,"We study the motion of Brownian particle in modulated media in the strong
+damping limit by using {\em toy model}, with special emphasis on the transition
+from localise to diffusive behavior. By using model potential we have seen the
+localised behavior when the number of minima of the potential is finite in the
+asymptotic time limit. In the limit of infinite number of minima we have seen
+the diffusive behavior.We calculate exactly the diffusion coefficient in
+periodic field of force. We have also studied the transport in commensurate and
+incommensurate media.",0702092v1
+2004-09-10,A Nonlinear Coupling Network to Simulate the Development of the r-mode Instablility in Neutron Stars I. Construction,"R-modes of a rotating neutron star are unstable because of the emission of
+gravitational radiation. We explore the saturation amplitudes of these modes
+determined by nonlinear mode-mode coupling. Modelling the star as
+incompressible allows the analytic computation of the coupling coefficients.
+All couplings up to n=30 are obtained, and analytic values for the shear
+damping and mode normalization are presented. In a subsequent paper we perform
+numerical simulations of a large set of coupled modes.",0409048v1
+1996-03-25,Fermion Scattering at a Phase Wave,"We study fermion reflection at a phase wave which is formed during a bubble
+collision in a first order phase transition. We calculate the reflection and
+the transmission coefficients by solving the Dirac equation with the phase wave
+background. Using the results we analyze the damping and the velocity of the
+wave.",9603401v2
+2003-06-01,Asymptotic Quasinormal Frequencies of d-dimensional Schwarzschild Black Holes,"We determine the quasinormal frequencies for all gravitational perturbations
+of the d-dimensional Schwarzschild black hole, in the infinite damping limit.
+Using the potentials for gravitational perturbations derived recently by
+Ishibashi and Kodama, we show that in all cases the asymptotic real part of the
+frequency is proportional to the Hawking temperature with a coefficient of log
+3. Via the correspondence principle, this leads directly to an equally spaced
+entropy spectrum. We comment on the possible implications for the spacing of
+eigenvalues of the Virasoro generator in the associated near-horizon conformal
+algebra.",0306004v2
+2002-03-05,Broken symmetries and pattern formation in two-frequency forced Faraday waves,"We exploit the presence of approximate (broken) symmetries to obtain general
+scaling laws governing the process of pattern formation in weakly damped
+Faraday waves. Specifically, we consider a two-frequency forcing function and
+trace the effects of time translation, time reversal and Hamiltonian structure
+for three illustrative examples: hexagons, two-mode superlattices, and two-mode
+rhomboids. By means of explicit parameter symmetries, we show how the size of
+various three-wave resonant interactions depends on the frequency ratio m:n and
+on the relative temporal phase of the two driving terms. These symmetry-based
+predictions are verified for numerically calculated coefficients, and help
+explain the results of recent experiments.",0203004v1
+1997-02-12,A self-consistent treatment of the dynamics of stable and unstable collective modes,"We address the dynamics of damped collective modes in terms of first and
+second moments. The modes are introduced in a self-consistent fashion with the
+help of a suitable application of linear response theory. Quantum effects in
+the fluctuations are governed by diffusion coefficients D_{\mu\nu}. The latter
+are obtained through a fluctuation dissipation theorem generalized to allow for
+a treatment of unstable modes. Numerical evaluations of the D_{\mu\nu} are
+presented. We discuss briefly how this picture may be used to describe global
+motion within a locally harmonic approximation.",9702029v1
+2005-01-07,Velocity-Space Diffusion in a Perpendicularly Propagating Electrostatic Wave,"The motion of ions in the fields B = B_0 zhat and E = E_0 yhat cos(k_perp y -
+omega t) is considered. When omega >> Omega_i and v_perp > omega/k_perp, the
+equations of motion may be reduced to a set of difference equations. These
+equations exhibit stochastic behavior when E_0 exceeds a threshold. The
+diffusion coefficient above the threshold is determined. Far above the
+threshold, ion Landau damping is recovered. Extension of the method to include
+parallel propagation is outlined.",0501035v1
+2002-05-20,Selection of Squeezed States via Decoherence,"In the framework of Lindblad theory for open quantum systems, we calculate
+the entropy of a damped quantum harmonic oscillator which is initially in a
+quasi-free state. The maximally predictable states are identified as those
+states producing the minimum entropy increase after a long enough time. In
+general, the states with a squeezing parameter depending on the environment's
+diffusion coefficients and friction constant are singled out, but if the
+friction constant is much smaller than the oscillator's frequency, coherent
+states
+  (or thermalized coherent states) are obtained as the preferred classical
+states.",0205127v1
+2002-06-17,Damped Bloch oscillations of cold atoms in optical lattices,"The paper studies Bloch oscillations of cold neutral atoms in the optical
+lattice. The effect of spontaneous emission on the dynamics of the system is
+analyzed both analytically and numerically. The spontaneous emission is shown
+to cause (i) the decay of Bloch oscillations with the decrement given by the
+rate of spontaneous emission and (ii) the diffusive spreading of the atoms with
+a diffusion coefficient depending on {\em both} the rate of spontaneous
+emission and the Bloch frequency.",0206108v1
+2005-06-22,A degenerate three-level laser with a parametric amplifier,"The aim of this paper is to study the squeezing and statistical properties of
+the light produced by a degenerate three-level laser whose cavity contains a
+degenerate parametric amplifier. In this quantum optical system the top and
+bottom levels of the three-level atoms injected into the laser cavity are
+coupled by the pump mode emerging from the parametric amplifier. For a linear
+gain coefficient of 100 and for a cavity damping constant of 0.8, the maximum
+intracavity squeezing is found at steady state and at threshold to be 93%.",0506178v3
+2006-04-28,Purity of states in the theory of open quantum systems,"The condition of purity of states for a damped harmonic oscillator is
+considered in the framework of Lindblad theory for open quantum systems. For a
+special choice of the environment coefficients, the correlated coherent states
+are shown to be the only states which remain pure all the time during the
+evolution of the considered system. These states are also the most stable under
+evolution in the presence of the environment.",0604212v1
+2007-05-08,Theoretical Analysis of Subthreshold Oscillatory Behaviors in Nonlinear Autonomous Systems,"We have developed a linearization method to investigate the subthreshold
+oscillatory behaviors in nonlinear autonomous systems. By considering firstly
+the neuronal system as an example, we show that this theoretical approach can
+predict quantitatively the subthreshold oscillatory activities, including the
+damping coefficients and the oscillatory frequencies which are in good
+agreement with those observed in experiments. Then we generalize the
+linearization method to an arbitrary autonomous nonlinear system. The detailed
+extension of this theoretical approach is also presented and further discussed.",0705.1019v1
+2007-06-03,A class of series acceleration formulae for Catalan's constant,"In this note, we develop transformation formulae and expansions for the log
+tangent integral, which are then used to derive series acceleration formulae
+for certain values of Dirichlet L-functions, such as Catalan's constant. The
+formulae are characterized by the presence of an infinite series whose general
+term consists of a linear recurrence damped by the central binomial coefficient
+and a certain quadratic polynomial. Typically, the series can be expressed in
+closed form as a rational linear combination of Catalan's constant and pi times
+the logarithm of an algebraic unit.",0706.0356v1
+2007-08-21,Dimer diffusion in a washboard potential,"The transport of a dimer, consisting of two Brownian particles bounded by a
+harmonic potential, moving on a periodic substrate is investigated both
+numerically and analytically. The mobility and diffusion of the dimer center of
+mass present distinct properties when compared with those of a monomer under
+the same transport conditions. Both the average current and the diffusion
+coefficient are found to be complicated non-monotonic functions of the driving
+force. The influence of dimer equilibrium length, coupling strength and damping
+constant on the dimer transport properties are also examined in detail.",0708.2858v2
+2007-10-25,Casimir energy and entropy between dissipative mirrors,"We discuss the Casimir effect between two identical, parallel slabs,
+emphasizing the role of dissipation and temperature. Starting from quite
+general assumptions, we analyze the behavior of the Casimir entropy in the
+limit T->0 and link it to the behavior of the slab's reflection coefficients at
+low frequencies. We also derive a formula in terms of a sum over modes, valid
+for dissipative slabs that can be interpreted in terms of a damped quantum
+oscillator.",0710.4915v2
+2007-12-19,Hyperon bulk viscosity in the presence of antikaon condensate,"We investigate the hyperon bulk viscosity due to the non-leptonic process $n
++ p \rightleftharpoons p + \Lambda $ in $K^-$ condensed matter and its effect
+on the r-mode instability in neutron stars. We find that the hyperon bulk
+viscosity coefficient in the presence of antikaon condensate is suppressed
+compared with the case without the condensate. The suppressed hyperon bulk
+viscosity in the superconducting phase is still an efficient mechanism to damp
+the r-mode instability in neutron stars.",0712.3171v2
+2008-06-24,A Gear-like Predictor-Corrector method for Brownian Dynamics Simulation,"We introduce a Predictor-Corrector type method suitable for performing
+many-particle Brownian Dynamics simulations. Since the method goes over to the
+Gear's method for Molecular Dynamics simulation in the limit of vanishing
+friction, we refer to it as a Gear-like algorithm. The algorithm has been
+tested on a one-dimensional, stochastically damped harmonic oscillator model,
+showing that it can cover a wide range of friction coefficients with a
+high-order accuracy, excellent stability, and a very small energy drift on the
+long time scales.",0806.3912v2
+2008-08-29,Kramers Theory for Conformational Transitions of Macromolecules,"We consider the application of Kramers theory to the microscopic calculation
+of rates of conformational transitions of macromolecules. The main difficulty
+in such an approach is to locate the transition state in a huge configuration
+space. We present a method which identifies the transition state along the most
+probable reaction pathway. It is then possible to microscopically compute the
+activation energy, the damping coefficient, the eigenfrequencies at the
+transition state and obtain the rate, without any a-priori choice of a reaction
+coordinate. Our theoretical results are tested against the results of Molecular
+Dynamics simulations for transitions in a 2-dimensional double well and for the
+cis-trans isomerization of a linear molecule.",0809.0027v1
+2008-12-30,Bulk viscosity of strange matter and r-modes in neutron stars,"We discuss bulk viscosity due to non-leptonic processes involving hyperons
+and Bose-Einstein condensate of negatively charged kaons in neutron stars. It
+is noted that the hyperon bulk viscosity coefficient is a few order of
+magnitude larger than that of the case with the condensate. Further it is found
+that the hyperon bulk viscosity is suppressed in a superconducting phase. The
+hyperon bulk viscosity efficiently damps the r-mode instability in neutron
+stars irrespective of whether a superconducting phase is present or not in
+neutron star interior.",0812.5021v1
+2009-05-01,Asymptotic behavior of second-order dissipative evolution equations combining potential with non-potential effects,"We study the asymptotic convergence properties, as the time variable goes to
+infinity, of trajectories of second-order dissipative evolution equations
+combining potential with non-potential effects. We exhibit a sharp condition,
+involving the damping parameter and the cocoercive coefficient of the
+non-potential operator, which guarantees convergence to equilibria of the
+trajectories. Applications are given to constrained optimization, fixed point
+problems, dynamical approach to Nash equilibria, and asymptotic stabilization
+in the case of a continuum of equilibria.",0905.0092v1
+2010-02-09,The pulse and monochromatic light stimulation of semiconductor quantum wells,"The light reflectance and absorbance are calculated for a quantum well (QW)
+the width of which is comparable with the light wave length. The difference of
+the refraction coefficients of the quantum well and barriers is taken into
+account. The stimulating pulse form is arbitrary. An existence of two closely
+situated discrete excitation energy levels is supposed. Such energy level pare
+may correspond to two magnetopolaron states in a quantizing magnetic field
+perpendicular to the QW plane. The relationship of the radiative and
+non-radiative damping is arbitrary. The final results does not use the
+approximation of the weak Coulomb interaction of electrons and holes.",1002.1780v1
+2010-02-09,Asymptotical photon distributions in the dissipative Dynamical Casimir Effect,"Asymptotical formulas for the photon distribution function of a quantum
+oscillator with time-dependent frequency and damping coefficients, interacting
+with a thermal reservoir, are derived in the case of a large mean number of
+quanta. Different regimes of excitation of an initial thermal state with an
+arbitrary temperature are considered. New formulas are used to predict the
+statistical properties of the electromagnetic field created in the experiments
+on the Dynamical Casimir Effect which are now under preparation.",1002.1861v1
+2010-03-12,Symmetry Analysis of 2+1 dimensional Burgers equation with variable damping,"The symmetry classification of the two dimensional Burgers equation with
+variable coefficient is considered. Symmetry algebra is found and a
+classification of its subalgebras, up to conjugacy, is obtained. Similarity
+reductions are performed for each class.",1003.2511v1
+2010-06-14,Transport parameters in neutron stars from in-medium NN cross sections,"We present a numerical study of shear viscosity and thermal conductivity of
+symmetric nuclear matter, pure neutron matter and $\beta$-stable nuclear
+matter, in the framework of the Brueckner theory. The calculation of in-medium
+cross sections and nucleon effective masses is performed with a consistent two
+and three body interaction. The investigation covers a wide baryon density
+range as requested in the applications to neutron stars. The results for the
+transport coefficients in $\beta$-stable nuclear matter are used to make
+preliminary predictions on the damping time scales of non radial modes in
+neutron stars.",1006.2656v1
+2010-12-10,Spin-orbit driven ferromagnetic resonance: A nanoscale magnetic characterisation technique,"We demonstrate a scalable new ferromagnetic resonance (FMR) technique based
+on the spin-orbit interaction. An alternating current drives FMR in uniform
+ferromagnetic structures patterned from the dilute magnetic semiconductors
+(Ga,Mn)As and (Ga,Mn)(As,P). This allows the direct measurement of magnetic
+anisotropy coefficients and damping parameters for individual nano-bars. By
+analysing the ferromagnetic resonance lineshape, we perform vector magnetometry
+on the current-induced driving field, observing contributions with symmetries
+of both the Dresselhaus and Rashba spin-orbit interactions.",1012.2397v1
+2011-09-28,Local solvability and loss of smoothness of the Navier-Stokes-Maxwell equations with large initial data,"Existence of local-in-time unique solution and loss of smoothness of full
+Magnet-Hydro-Dynamics system (MHD) is considered for periodic initial data. The
+result is proven using Fujita-Kato's method in $\ell^1$ based (for the Fourier
+coefficients) functional spaces enabling us to easily estimate nonlinear terms
+in the system as well as solutions to Maxwells's equations. A loss of
+smoothness result is shown for the velocity and magnetic field. It comes from
+the damped-wave operator which does not have any smoothing effect.",1109.6089v1
+2011-12-12,On the vanishing electron-mass limit in plasma hydrodynamics in unbounded media,"We consider the zero-electron-mass limit for the Navier-Stokes-Poisson system
+in unbounded spatial domains. Assuming smallness of the viscosity coefficient
+and ill-prepared initial data, we show that the asymptotic limit is represented
+by the incompressible Navier-Stokes system, with a Brinkman damping, in the
+case when viscosity is proportional to the electron-mass, and by the
+incompressible Euler system provided the viscosity is dominated by the electron
+mass. The proof is based on the RAGE theorem and dispersive estimates for
+acoustic waves, and on the concept of suitable weak solutions for the
+compressible Navier-Stokes system.",1112.2562v1
+2014-05-03,Lie Symmetry Classification and Numerical Analysis of KdV Equation with Power-law Nonlinearity,"In this paper, a complete Lie symmetry analysis of the damped wave equation
+with time-dependent coefficients is investigated. Then the invariant solutions
+and the exact solutions generated from the symmetries are presented. Moreover,
+a Lie algebraic classifications and the optimal system are discussed. Finally,
+using Chebyshev pseudo-spectral method (CPSM), a numerical analysis to solve
+the invariant solutions corresponded the Lie symmetries of main equation is
+presented. This method applies the Chebyshev-Gauss-Lobatto points as
+collocation points.",1405.0592v3
+2015-02-22,Fractional extension of Kramers rate and barrier escaping from metastable potential well,"The reactive process of barrier escaping from the metastable potential well
+is studied together with the extension of Kramers' rate formula to the
+fractional case. Characteristic quantities are computed for an thimbleful of
+insight into the near barrier escaping and recrossing dynamics. Where the
+stationary transmission coefficient is revealed to be larger than the usual
+cases which implies less barrier recrossing. And the non-monotonic varying of
+it reveals a close dependence to the fractional exponent $\alpha$. In most
+cases, the near barrier behavior of the escaping dynamics is equivalent to the
+diffusion in the two-dimensional non-Ohmic damping system.",1502.06184v1
+2016-02-20,Synchronization of two couple pendula in absence of escapement,"A model of two oscillating pendula placed on a mobile support is studied.
+Once an overall scheme of equations, under general assumptions, is formulated
+via the Lagrangian equations of motion, the specific case of absence of
+escapement is examined. The mechanical models consists of two coupled pendula
+both oscillating on a moving board attached to a spring. The final result
+performs a selection among the peculiar parameters of the physical process
+(lenghts, ratio of masses, friction and damping coefficients, stiffness of the
+spring) which provide a tendency to synchronization.",1602.06382v1
+2016-06-06,Weak invariants of time-dependent quantum dissipative systems,"The concept of weak invariant is introduced. Then, the weak invariants
+associated with time-dependent quantum dissipative systems are discussed in the
+context of master equations of the Lindblad type. In particular, with the help
+of the su(1,1) Lie-algebraic structure, the weak invariant is explicitly
+constructed for the quantum damped harmonic oscillator with the time-dependent
+frequency and friction coefficient. This generalizes the Lewis-Riesenfeld
+invariant to the case of nonunitary dynamics in the Markovian approximation.",1606.01767v4
+2017-06-25,Influence of qubits' nonradiative decay into a common bath on the transport properties of microwave photons,"We consider the influence of nonradiative damping of qubits on the microwave
+transport of photons, propagating in an open one-dimensional microstrip line.
+Within the framework of the formalism of a non-Hermitian Hamiltonian we
+obtained the expressions for the transmission and reflection coefficients for
+two qubits which explicitly account for the indirect interaction between qubits
+due to nonradiative decay into common bath. It is shown that this interaction
+leads to the results that are significantly different from those already known",1706.08028v2
+2018-07-17,Energy decay for evolution equations with delay feedbacks,"We study abstract linear and nonlinear evolutionary systems with single or
+multiple delay feedbacks, illustrated by several concrete examples. In
+particular, we assume that the operator associated with the undelayed part of
+the system generates an exponentially stable semigroup and that the delay
+damping coefficients are locally integrable in time. A step by step procedure
+combined with Gronwall's inequality allows us to prove the existence and
+uniqueness of solutions. Furthermore, under appropriate conditions we obtain
+exponential decay estimates.",1807.06445v2
+2018-08-22,Weak convergence of Euler-Maruyama's approximation for SDEs under integrability condition,"This work establishes the weak convergence of Euler-Maruyama's approximation
+for stochastic differential equations (SDEs) with singular drifts under the
+integrability condition in lieu of the widely used growth condition. This
+method is based on a skillful application of the dimension-free Harnack
+inequality. Moreover, when the drifts satisfy certain regularity conditions,
+the convergence rate is estimated. This method is also applicable when the
+diffusion coefficients are degenerate. A stochastic damping Hamiltonian system
+is studied as an illustrative example.",1808.07250v1
+2019-11-30,Robustness Evaluation of the Butterfly Optimization Algorithm on a Control System,"In this paper, the Butterfly Optimization Algorithm (BOA) proposed by [1] is
+adopted to optimize the parameters of a designed Lead-Lad Controller so as to
+obtain a stabilized control system. Numerical analysis was carried out for BOA
+on the control problem and the results are compared to those obtained from the
+well known Genetic Algorithm (GA) and Differential Evolution (DE) Algorithm.
+BOA performs better in terms of eigenvalue analysis but similar to GA and DE in
+terms of optimizing the minimum damping coefficient for the control system",1912.00185v1
+2019-12-05,Blow up for small-amplitude semilinear wave equations with mixed nonlinearities on asymptotically Euclidean manifolds,"In this work, we investigate the problem of finite time blow up as well as
+the upper bound estimates of lifespan for solutions to small-amplitude
+semilinear wave equations with mixed nonlinearities $a |u_t|^p+b |u|^q$, posed
+on asymptotically Euclidean manifolds, which is related to both the Strauss
+conjecture and Glassey conjecture. In some cases, we obtain existence results,
+where the lower bound of the lifespan agrees with the upper bound in order. In
+addition, our results apply for semilinear damped wave equations, when the
+coefficient of the dissipation term is integrable (without sign condition) and
+space-independent.",1912.02561v1
+2020-03-16,Extreme Hawking Radiation,"Modeling the collapse of an extreme Reissner-Nordstr\""om (ERN) black hole by
+solving the corresponding moving mirror model for the trajectory that
+asymptotically approaches uniform acceleration, we obtain the non-zero beta
+coefficients for all times. Finite energy is emitted, the radiation spectra is
+non-thermal (non-steady / not Planck), soft particles characterize the
+evaporation, and particle production at ultra-late times is damped.
+Entanglement entropy diverges with no Page curve turn-over, demonstrating
+non-thermal information loss. The radiation obeys time-reversal symmetry.",2003.07016v1
+2021-02-01,"Comment on ""Deformed Fokker-Planck equation: inhomogeneous medium with a position-dependent mass""","In a recent paper by B. G. da Costa {\it et al.} [Phys. Rev. E 102,
+062105(2020)], the phenomenological Langevin equation and the corresponding
+Fokker-Planck equation for an inhomogeneous medium with a position-dependent
+particle mass and position-dependent damping coefficient have been studied. The
+aim of this comment is to present a microscopic derivation of the Langevin
+equation for such a system. It is not equivalent to that in the commented
+paper.",2102.00699v1
+2021-02-05,Nonequilibrium statistical mechanics of crystals,"The local equilibrium approach previously developed by the Authors [J.
+Mabillard and P. Gaspard, J. Stat. Mech. (2020) 103203] for matter with broken
+symmetries is applied to crystalline solids. The macroscopic hydrodynamics of
+crystals and their local thermodynamic and transport properties are deduced
+from the microscopic Hamiltonian dynamics. In particular, the Green-Kubo
+formulas are obtained for all the transport coefficients. The eight
+hydrodynamic modes and their dispersion relation are studied for general and
+cubic crystals. In the same twenty crystallographic classes as those compatible
+with piezoelectricity, cross effects coupling transport between linear momentum
+and heat or crystalline order are shown to split the degeneracy of damping
+rates for modes propagating in opposite generic directions.",2102.03096v1
+2021-03-14,A note on damped wave equations with a nonlinear dissipation in non-cylindrical domains,"In this paper, we study the large time behavior of a class of wave equation
+with a nonlinear dissipation in non-cylindrical domains. The result we obtained
+here relaxes the conditions for the nonlinear term coefficients (in precise,
+that is $\beta(t)|u|^\rho u$) in \cite{alb} and \cite{ha} (which require
+$\beta(t)$ to be a constant or $\beta(t)$ to be decreasing with time $t$) and
+has less restriction for the defined regions.",2103.09678v2
+2021-03-28,"Skyrmion elongation, duplication and rotation by spin-transfer torque under spatially varying spin current","The effect of the spatially varying spin current on a skyrmion is numerically
+investigated. It is shown that an inhomogeneous current density induces an
+elongation of the skyrmion. This elongation can be controlled using current
+pulses of different strength and duration. Long current pulses lead to a
+splitting that forms two replicas of the initial skyrmion while for short
+pulses the elongated skyrmion relaxes back to its initial circular state
+through rotation in the MHz-GHz frequency range. The frequency is dependent on
+the strength of the damping coefficient.",2103.15094v1
+2021-05-13,Thermal instability in a ferrimagnetic resonator strongly coupled to a loop-gap microwave cavity,"We study nonlinear response of a ferrimagnetic sphere resonator (FSR)
+strongly coupled to a microwave loop gap resonator (LGR). The measured response
+in the regime of weak nonlinearity allows the extraction of the FSR Kerr
+coefficient and its cubic damping rate. We find that there is a certain range
+of driving parameters in which the system exhibits instability. In that range,
+self-sustained modulation of the reflected power off the system is generated.
+The instability is attributed to absorption-induced heating of the FSR above
+its Curie temperature.",2105.06102v2
+2022-01-25,A fully adaptive explicit stabilized integrator for advection-diffusion-reaction problems,"A novel second order family of explicit stabilized Runge-Kutta-Chebyshev
+methods for advection-diffusion-reaction equations is introduced. The new
+methods outperform existing schemes for relatively high Peclet number due to
+their favorable stability properties and explicitly available coefficients. The
+construction of the new schemes is based on stabilization using second kind
+Chebyshev polynomials first used in the construction of the stochastic
+integrator SK-ROCK. An adaptive algorithm to implement the new scheme is
+proposed. This algorithm is able to automatically select the suitable step
+size, number of stages, and damping parameter at each integration step.
+Numerical experiments that illustrate the efficiency of the new algorithm are
+presented.",2201.10206v2
+2022-11-08,Current and diffusion of Overdamped Active Brownian Particles in a Ratchet Potential,"The transport properties of a spherical active Brownian particle in a
+periodic potential under heavy damping are considered. The self-propelled
+particle is subjected to the asymmetric potential, detailed balance is lost and
+the particles generate a non-zero drift speed.
+  The average current is calculated and the diffusivity of the particle is
+analyzed from the effective diffusion coefficient. For chiral active particles,
+the diffusivity decreases with increasing the angular velocity, confining the
+particle near the initial position, and reducing the average current.",2211.04298v1
+2022-12-24,Anisotropic acoustics in dipolar Fermi gases,"We consider plane wave modes in ultracold, but not quantum degenerate,
+dipolar Fermi gases in the hydrodynamic limit. Longitudinal waves present
+anisotropies in both the speed of sound and their damping, and experience a
+small, undulatory effect in their flow velocity. Two distinct types of shear
+waves appear, a ``familiar"" one, and another that is accompanied by nontrivial
+density and temperature modulations. We propose these shear modes as an
+experimental means to measure the viscosity coefficients, including their
+anisotropies.",2212.12659v1
+2023-02-09,Two-loop hard thermal loops for any model,"Hard thermal loops describe how soft gauge fields are screened and damped in
+hot plasmas. As such they are used to calculate transport coefficients,
+Sphaleron rates, equations of state, and particle production. However, most
+calculations are done using one-loop self-energies. And two-loop contributions
+can be large. To that end this paper provides vector two-loop self-energies for
+generic models: Any scalar, fermion, or vector representation; and all possible
+renormalizable terms. Several examples are given to showcase the results.
+Two-loop results for higher-point functions are also given.",2302.04894v1
+2024-01-29,Dissipative effects on the propagation of spin modes,"In relativistic hydrodynamics with spin, following de Groot--van Leeuwen--van
+Weert's energy-momentum and spin tensor definitions, we analyze the propagation
+of spin degrees of freedom. We deduce an analytical formula for spin wave
+velocity, finding that it approaches half the speed of light in the
+ultra-relativistic limit. Only transverse degrees of freedom propagate, similar
+to electromagnetic waves. Additionally, we explore dissipative effects and
+determine the damping coefficients for Maxwell-J\""uttner statistics.",2401.16007v1
+2024-03-05,Microscopic parametrization of the near threshold oscillations of the nucleon time-like effective electromagnetic form factors,"We present an analysis of the recent near threshold BESIII data for the
+nucleon time-like effective form factors. The damped oscillation emerging from
+the subtraction of the dipole formula is treated in non-perturbative-QCD,
+making use of the light cone distribution amplitudes expansion.
+Non-perturbative effects are accounted for by considering Q2-dependent
+coefficients in such expansions, whose free parameters are determined by
+fitting to the proton and neutron data. Possible implications and future
+analysis have been discussed.",2403.02916v1
+2017-07-28,Measurements of the Temperature and E-Mode Polarization of the CMB from 500 Square Degrees of SPTpol Data,"We present measurements of the $E$-mode polarization angular auto-power
+spectrum ($EE$) and temperature-$E$-mode cross-power spectrum ($TE$) of the
+cosmic microwave background (CMB) using 150 GHz data from three seasons of
+SPTpol observations. We report the power spectra over the spherical harmonic
+multipole range $50 < \ell \leq 8000$, and detect nine acoustic peaks in the
+$EE$ spectrum with high signal-to-noise ratio. These measurements are the most
+sensitive to date of the $EE$ and $TE$ power spectra at $\ell > 1050$ and $\ell
+> 1475$, respectively. The observations cover 500 deg$^2$, a fivefold increase
+in area compared to previous SPTpol analyses, which increases our sensitivity
+to the photon diffusion damping tail of the CMB power spectra enabling tighter
+constraints on \LCDM model extensions. After masking all sources with
+unpolarized flux $>50$ mJy we place a 95% confidence upper limit on residual
+polarized point-source power of $D_\ell = \ell(\ell+1)C_\ell/2\pi
+<0.107\,\mu{\rm K}^2$ at $\ell=3000$, suggesting that the $EE$ damping tail
+dominates foregrounds to at least $\ell = 4050$ with modest source masking. We
+find that the SPTpol dataset is in mild tension with the $\Lambda CDM$ model
+($2.1\,\sigma$), and different data splits prefer parameter values that differ
+at the $\sim 1\,\sigma$ level. When fitting SPTpol data at $\ell < 1000$ we
+find cosmological parameter constraints consistent with those for $Planck$
+temperature. Including SPTpol data at $\ell > 1000$ results in a preference for
+a higher value of the expansion rate ($H_0 = 71.3 \pm
+2.1\,\mbox{km}\,s^{-1}\mbox{Mpc}^{-1}$ ) and a lower value for present-day
+density fluctuations ($\sigma_8 = 0.77 \pm 0.02$).",1707.09353v3
+1999-04-13,Damping of Collective Nuclear Motion and Thermodynamic Properties of Nuclei beyond Mean Field,"The dynamical description of correlated nuclear motion is based on a set of
+coupled equations of motion for the one-body density matrix $\rho (11';t)$ and
+the two-body correlation function $c_2(12,1'2';t)$, which is obtained from the
+density-matrix hierarchy beyond conventional mean-field approaches by
+truncating 3-body correlations. The resulting equations nonperturbatively
+describe particle-particle collisions (short-range correlations) as well as
+particle-hole interactions (long-range correlations). Within a basis of
+time-dependent Hartree-Fock states these equations of motion are solved for
+collective vibrations of $^{40}Ca$ at several finite thermal excitation
+energies corresponding to temperatures $T=0-6$ MeV. Transport coefficients for
+friction and diffusion are extracted from the explicit solutions in comparison
+to the solutions of the associated TDHF, VUU, Vlasov or damped quantum
+oscillator equations of motion. We find that the actual magnitude of the
+transport coefficients is strongly influenced by partlicle-hole correlations at
+low temperature which generate large fluctuations in the nuclear shape degrees
+of freedom. Thermodynamically, the specific heat and the entropy of the system
+as a function of temperature does not differ much from the mean-field limit
+except for a bump in the specific heat around $T\simeq 4$ MeV which we
+attribute to the melting of shell effects in the correlated system.",9904034v1
+2010-09-30,An efficient numerical algorithm for the L2 optimal transport problem with applications to image processing,"We present a numerical method to solve the optimal transport problem with a
+quadratic cost when the source and target measures are periodic probability
+densities. This method is based on a numerical resolution of the corresponding
+Monge-Amp\`ere equation. We extend the damped Newton algorithm of Loeper and
+Rapetti \cite{LR} to the more general case of a non uniform density which is
+relevant to the optimal transport problem, and we show that our algorithm
+converges for sufficiently large damping coefficients. The main idea consists
+of designing an iterative scheme where the fully nonlinear equation is
+approximated by a non-constant coefficient linear elliptic PDE that we solve
+numerically. We introduce several improvements and some new techniques for the
+numerical resolution of the corresponding linear system. Namely, we use a Fast
+Fourier Transform (FFT) method by Strain \cite{St}, which allows to increase
+the efficiency of our algorithm against the standard finite difference method.
+Moreover, we use a fourth order finite difference scheme to approximate the
+partial derivatives involved in the nonlinear terms of the Newton algorithm,
+which are evaluated once at each iteration; this leads to a significant
+improvement of the accuracy of the method, but does not sacrifice its
+efficiency. Finally, we present some numerical experiments which demonstrate
+the robustness and efficiency of our method on several examples of image
+processing, including an application to multiple sclerosis disease detection.",1009.6039v2
+2010-10-13,Global Uniqueness and Stability in Determining the Damping Coefficient of an Inverse Hyperbolic Problem with Non-Homogeneous Neumann B.C. through an Additional Dirichlet Boundary Trace,"We consider a second-order hyperbolic equation on an open bounded domain
+$\Omega$ in $\mathbb{R}^n$ for $n\geq2$, with $C^2$-boundary
+$\Gamma=\pa\Omega=\bar{\Gamma_0\cup\Gamma_1}$,
+$\Gamma_0\cap\Gamma_1=\emptyset$, subject to non-homogeneous Neumann boundary
+conditions on the entire boundary $\Gamma$. We then study the inverse problem
+of determining the interior damping coefficient of the equation by means of an
+additional measurement of the Dirichlet boundary trace of the solution, in a
+suitable, explicit sub-portion $\Gamma_1$ of the boundary $\Gamma$, and over a
+computable time interval $T>0$. Under sharp conditions on the complementary
+part $\Gamma_0= \Gamma\backslash\Gamma_1$, $T>0$, and under weak regularity
+requirements on the data, we establish the two canonical results in inverse
+problems: (i) uniqueness and (ii) stability (at the $L^2$-level). The latter
+(ii) is the main result of the paper. Our proof relies on three main
+ingredients: (a) sharp Carleman estimates at the $H^1 \times L_2$-level for
+second-order hyperbolic equations \cite{L-T-Z.1}; (b) a correspondingly implied
+continuous observability inequality at the same energy level \cite{L-T-Z.1};
+(c) sharp interior and boundary regularity theory for second-order hyperbolic
+equations with Neumann boundary data \cite{L-T.4}, \cite{L-T.5}, \cite{L-T.6},
+\cite{Ta.3}. The proof of the linear uniqueness result (Section 4, step 5) also
+takes advantage of a convenient tactical route ""post-Carleman estimates""
+suggested by V.Isakov in \cite[Thm.\,8.2.2, p.\,231]{Is.2}.",1010.2696v2
+2013-10-31,Impurity Screening and Surface Acoustic Wave Absorption in a Dipolar Exciton Condensate at Finite Temperatures,"We describe the behavior of a repulsively interacting Bose-Einstein
+condensate of indirect dipolar exciton gas in a double quantum well (QW) system
+under external static or dynamic electric fields at finite temperatures.
+Electrostatic perturbation is considered to be created by an impurity atom or
+shot-range defect of QW fluctuation. The screening of this defect potential by
+an exciton condensate is studied. We find asymptotic spatial dependence of the
+screened potential and analyse its dependence on the temperature and exciton
+concentration. It is shown that the asymptotic of the screened potential has a
+steep power law dependence in contrast to the well known results of electron
+gas. This peculiarity reflects the bosonic nature of the exciton condensate.
+The behavior of exciton condensate under external alternative field created by
+a surface acoustic wave (SAW) is examined in detail. We focus our attention on
+the dependence of SAW absorption coefficient on temperature and exciton
+concentration. We found that at zero temperatures Landau damping does not
+contribute to the SAW absorption, but the Belyaev mechanism produces unusual
+behavior of SAW absorption coefficient on exciton concentration: if the exciton
+concentration exceeds some critical value, the SAW absorption vanishes. At
+finite temperatures Landau damping comes into action and results in washing out
+the sharp absorption behavior. Such unusual SAW absorption properties can be
+used for experimental evidence of the exciton condensation. This method is also
+applicable to the experimental testing of both dark and bright exciton
+condensates, that is impossible to do with the optical luminescence technique.",1310.8394v1
+2015-04-05,Stability of non-autonomous difference equations with applications to transport and wave propagation on networks,"In this paper, we address the stability of transport systems and wave
+propagation on networks with time-varying parameters. We do so by reformulating
+these systems as non-autonomous difference equations and by providing a
+suitable representation of their solutions in terms of their initial conditions
+and some time-dependent matrix coefficients. This enables us to characterize
+the asymptotic behavior of solutions in terms of such coefficients. In the case
+of difference equations with arbitrary switching, we obtain a delay-independent
+generalization of the well-known criterion for autonomous systems due to Hale
+and Silkowski. As a consequence, we show that exponential stability of
+transport systems and wave propagation on networks is robust with respect to
+variations of the lengths of the edges of the network preserving their rational
+dependence structure. This leads to our main result: the wave equation on a
+network with arbitrarily switching damping at external vertices is
+exponentially stable if and only if the network is a tree and the damping is
+bounded away from zero at all external vertices but at most one.",1504.01116v4
+2016-11-24,Zero-Point Energy Leakage in Quantum Thermal Bath Molecular Dynamics Simulations,"The quantum thermal bath (QTB) has been presented as analternative to
+path-integral-based methods to introduce nuclear quantumeffects in molecular
+dynamics simulations. The method has proved to beefficient, yielding accurate
+results for various systems. However, the QTBmethod is prone to zero-point
+energy leakage (ZPEL) in highly anharmonicsystems. This is a well-known problem
+in methods based on classicaltrajectories where part of the energy of the
+high-frequency modes istransferred to the low-frequency modes leading to a
+wrong energydistribution. In some cases, the ZPEL can have dramatic
+consequences onthe properties of the system. Thus, we investigate the ZPEL by
+testing theQTB method on selected systems with increasing complexity in order
+to studythe conditions and the parameters that influence the leakage. We also
+analyze the consequences of the ZPEL on the structuraland vibrational
+properties of the system. We find that the leakage is particularly dependent on
+the damping coefficient and thatincreasing its value can reduce and, in some
+cases, completely remove the ZPEL. When using sufficiently high values for
+thedamping coefficient, the expected energy distribution among the vibrational
+modes is ensured. In this case, the QTB methodgives very encouraging results.
+In particular, the structural properties are well-reproduced. The dynamical
+properties should beregarded with caution although valuable information can
+still be extracted from the vibrational spectrum, even for large values ofthe
+damping term.",1611.08221v1
+2016-12-11,Temperature dependence of the plastic scintillator detector for DAMPE,"The Plastic Scintillator Detector (PSD) is one of the main sub-detectors in
+the DArk Matter Particle Explorer (DAMPE) project. It will be operated over a
+large temperature range from -$10$ to $30^{\circ}$C, so the temperature effect
+of the whole detection system should be studied in detail. The temperature
+dependence of the PSD system is mainly contributed by the three parts: the
+plastic scintillator bar, the photomultiplier tube (PMT), and the Front End
+Electronics (FEE). These three parts have been studied in detail and the
+contribution of each part has been obtained and discussed. The temperature
+coefficient of the PMT is $-0.320(\pm0.033)\%/^{\circ}$C, and the coefficient
+of the plastic scintillator bar is $-0.036(\pm0.038)\%/^{\circ}$C. This result
+means that after subtracting the FEE pedestal, the variation of the signal
+amplitude of the PMT-scintillator system due to temperature mainly comes from
+the PMT, and the plastic scintillator bar is not sensitive to temperature over
+the operating range. Since the temperature effect cannot be ignored, the
+temperature dependence of the whole PSD has been also studied and a correction
+has been made to minimize this effect. The correction result shows that the
+effect of temperature on the signal amplitude of the PSD system can be
+suppressed.",1612.03398v1
+2017-05-09,Recovery of mechanical pressure in a gas of underdamped active dumbbells with Brownian noise,"In contrast with a gas at thermodynamic equilibrium, the mean force exerted
+on a wall by a gas of active particles usually depends on the confining
+potential, thereby preventing a proper definition of mechanical pressure. In
+this paper, we investigate numerically the properties of a gas of underdamped
+self-propelled dumbbells subject to Brownian noise of increasing intensity, in
+order to understand how the notion of pressure is recovered as noise
+progressively masks the effects of self-propulsion and the system approaches
+thermodynamic equilibrium. The simulations performed for a mobile asymmetric
+wall separating two chambers containing an equal number of active dumbbells
+highlight some subtle and unexpected properties of the system. First, Brownian
+noise of moderate intensity is sufficient to let mean forces equilibrate for
+small values of the damping coefficient, while much stronger noise is required
+for larger values of the damping coefficient. Moreover, the displacement of the
+mean position of the wall upon increase of the intensity of the noise is not
+necessarily monotonous and may instead display changes of direction. Both facts
+actually reflect the existence of several mechanisms leading to the rupture of
+force balance, which tend to displace the mean position of the wall towards
+different directions and display different robustness against an increase of
+the intensity of Brownian noise. This work therefore provides a clear
+illustration of the fact that driving an autonomous system towards (or away
+from) thermodynamic equilibrium may not be a straightforward process, but may
+instead proceed through the variations of the relative weights of several
+conflicting mechanisms.",1705.03291v1
+2017-11-27,Colloidal particle adsorption at water/water interfaces with ultra-low interfacial tension,"Using fluorescence microscopy we study the adsorption of single latex
+microparticles at a water/water interface between demixing aqueous solutions of
+polymers, generally known as a water-in-water emulsion. Similar microparticles
+at the interface between molecular liquids have exhibited an extremely slow
+relaxation preventing the observation of expected equilibrium states. This
+phenomenon has been attributed to ""long-lived"" metastable states caused by
+significant energy barriers $\Delta{\cal F}\sim \gamma A_d\gg k_B T$ induced by
+high interfacial tension ($\gamma \sim 10^{-2}$ N/m) and nanoscale surface
+defects with characteristic areas $A_d \simeq$ 10--30 nm$^2$. For the studied
+water/water interface with ultra-low surface tension ($\gamma \sim 10^{-4}$
+N/m) we are able to characterize the entire adsorption process and observe
+equilibrium states prescribed by a single equilibrium contact angle independent
+of the particle size. Notably, we observe crossovers from fast initial dynamics
+to slower kinetic regimes analytically predicted for large surface defects
+($A_d \simeq$ 500 nm$^2$). Moreover, particle trajectories reveal a
+position-independent damping coefficient that is unexpected given the large
+viscosity contrast between phases. These observations are attributed to the
+remarkably diffuse nature of the water/water interface and the adsorption and
+entanglement of polymer chains in the semidilute solutions. This work offers
+some first insights on the adsorption dynamics/kinetics of microparticles at
+water/water interfaces in bio-colloidal systems.",1711.10024v2
+2018-09-19,Magnetic non-contact friction from domain wall dynamics actuated by oscillatory mechanical motion,"Magnetic friction is a form of non-contact friction arising from the
+dissipation of energy in a magnet due to spin reorientation in a magnetic
+field. In this paper we study magnetic friction in the context of
+micromagnetics, using our recent implementation of smooth spring-driven motion
+[Phys. Rev. E. 97, 053301 (2018)] to simulate ring-down measurements in two
+setups where domain wall dynamics is induced by mechanical motion. These
+include a single thin film with a domain wall in an external field and a setup
+mimicking a magnetic cantilever tip and substrate, in which the two magnets
+interact through dipolar interactions. We investigate how various micromagnetic
+parameters influence the domain wall dynamics actuated by the oscillatory
+spring-driven mechanical motion and the resulting damping coefficient. Our
+simulations show that the magnitude of magnetic friction can be comparable to
+other forms of non-contact friction. For oscillation frequencies lower than
+those inducing excitations of the internal structure of the domain walls, the
+damping coefficient is found to be independent of frequency. Hence, our results
+obtained in the frequency range from 8 to 112 MHz are expected to be relevant
+also for typical experimental setups operating in the 100 kHz range.",1809.07130v2
+2019-09-29,Tunable parametric amplification of a graphene nanomechanical resonator in the nonlinear regime,"Parametric amplification is widely used in nanoelectro-mechanical systems to
+enhance the transduced mechanical signals. Although parametric amplification
+has been studied in different mechanical resonator systems, the nonlinear
+dynamics involved receives less attention. Taking advantage of the excellent
+electrical and mechanical properties of graphene, we demonstrate electrical
+tunable parametric amplification using a doubly clamped graphene nanomechanical
+resonator. By applying external microwave pumping with twice the resonant
+frequency, we investigate parametric amplification in the nonlinear regime. We
+experimentally show that the extracted coefficient of the nonlinear Duffing
+force {\alpha} and the nonlinear damping coefficient {\eta} vary as a function
+of external pumping power, indicating the influence of higher-order
+nonlinearity beyond the Duffing (~x^3) and van der Pol (~x^2 dx/dt) types in
+our device. Even when the higher-order nonlinearity is involved, parametric
+amplification still can be achieved in the nonlinear regime. The parametric
+gain increases and shows a tendency of saturation with increasing external
+pumping power. Further, the parametric gain can be electrically tuned by the
+gate voltage with a maximum gain of 10.2 dB achieved at the gate voltage of 19
+V. Our results will benefit studies on nonlinear dynamics, especially nonlinear
+damping in graphene nanomechanical resonators that has been debated in the
+community over past decade.",1909.13219v2
+2019-11-21,Cosmic ray transport in starburst galaxies,"Starburst galaxies are efficient $\gamma$-ray producers, because their high
+supernova rates generate copious cosmic ray (CR) protons, and their high gas
+densities act as thick targets off which these protons can produce neutral
+pions and thence $\gamma$-rays. In this paper we present a first-principles
+calculation of the mechanisms by which CRs propagate through such environments,
+combining astrochemical models with analysis of turbulence in weakly ionised
+plasma. We show that CRs cannot scatter off the strong large-scale turbulence
+found in starbursts, because efficient ion-neutral damping prevents such
+turbulence from cascading down to the scales of CR gyroradii. Instead, CRs
+stream along field lines at a rate determined by the competition between
+streaming instability and ion-neutral damping, leading to transport via a
+process of field line random walk. This results in an effective diffusion
+coefficient that is nearly energy-independent up to CR energies of $\sim 1$
+TeV. We apply our computed diffusion coefficient to a simple model of CR escape
+and loss, and show that the resulting $\gamma$-ray spectra are in good
+agreement with the observed spectra of the starbursts NGC 253, M82, and Arp
+220. In particular, our model reproduces these galaxies' relatively hard GeV
+$\gamma$-ray spectra and softer TeV spectra without the need for any
+fine-tuning of advective escape times or the shape of the CR injection
+spectrum.",1911.09774v2
+2020-12-01,Solvable Theory of a Strange Metal at the Breakdown of a Heavy Fermi Liquid,"We introduce an effective theory for quantum critical points (QCPs) in heavy
+fermion systems, involving a change in carrier density without symmetry
+breaking. Our new theory captures a strongly coupled metallic QCP, leading to
+robust marginal Fermi liquid transport phenomenology, and associated linear in
+temperature ($T$) ""strange metal"" resistivity, all within a controlled large
+$N$ limit. In the parameter regime of strong damping of emergent bosonic
+excitations, the QCP also displays a near-universal ""Planckian"" transport
+lifetime, $\tau_{\mathrm{tr}}\sim\hbar/(k_BT)$. This is contrasted with the
+conventional so-called ""slave boson"" theory of the Kondo breakdown, where the
+large $N$ limit describes a weak coupling fixed point and non-trivial transport
+behavior may only be obtained through uncontrolled $1/N$ corrections. We also
+compute the weak-field Hall coefficient within the effective model as the
+system is tuned across the transition. We further find that between the two
+plateaus, reflecting the different carrier densities in the two Fermi liquid
+phases, the Hall coefficient can develop a peak in the critical crossover
+regime, like in recent experimental findings, in the parameter regime of weak
+boson damping.",2012.00763v2
+2021-11-30,Transient Stability of Low-Inertia Power Systems with Inverter-Based Generation,"This study examines the transient stability of low-inertia power systems with
+inverter-based generation (IBG) and proposes a sufficient stability criterion.
+In low-inertia grids, transient interactions are induced between the
+electromagnetic dynamics of the IBG and the electromechanical dynamics of the
+synchronous generator (SG) under a fault. For this, a hybrid IBG-SG system is
+established and a delta-power-frequency model is developed. Based on this
+model, new mechanisms of transient instability different from those of
+conventional power systems from the energy perspective are discovered. First,
+two loss-of-synchronization (LOS) types are identified based on the relative
+power imbalance owing to the mismatch between the inertia of the IBG and SG
+under a fault. Second, the relative angle and frequency will jump at the moment
+of a fault, thus affecting the system energy. Third, the cosine damping
+coefficient induces a positive energy dissipation, thereby contributing to the
+system stability. A unified criterion for identifying the two LOS types is
+proposed using the energy function method. This criterion is proved to be a
+sufficient stability condition for addressing the effects of the jumps and
+cosine damping coefficient on the system stability. The new mechanisms and
+effectiveness of the criterion are verified based on simulation results.",2111.15380v3
+2023-10-12,An improved dynamical Poisson equation solver for self-gravity,"Since self-gravity is crucial in the structure formation of the universe,
+many hydrodynamics simulations with the effect of self-gravity have been
+conducted. The multigrid method is widely used as a solver for the Poisson
+equation of the self-gravity; however, the parallelization efficiency of the
+multigrid method becomes worse when we use a massively parallel computer, and
+it becomes inefficient with more than $10^4$ cores, even for highly tuned
+codes. To perform large-scale parallel simulations ($> 10^4$ cores), developing
+a new gravity solver with good parallelization efficiency is beneficial. In
+this article, we develop a new self-gravity solver using the telegraph equation
+with a damping coefficient, $\kappa$. Parallelization is much easier than the
+case of the elliptic Poisson equation since the telegraph equation is a
+hyperbolic partial differential equation. We analyze convergence tests of our
+telegraph equations solver and determine that the best non-dimensional damping
+coefficient of the telegraph equations is $\tilde{\kappa} \simeq 2.5$. We also
+show that our method can maintain high parallelization efficiency even for
+massively parallel computations due to the hyperbolic nature of the telegraphic
+equation by weak-scaling tests. If the time step of the calculation is
+determined by heating/cooling or chemical reactions, rather than the CFL
+condition, our method may provide the method for calculating self-gravity
+faster than other previously known methods such as the fast Fourier transform
+and multigrid iteration solvers because gravitational phase velocity determined
+by the CFL condition using these timescales is much larger than the fluid
+velocity plus sound speed.",2310.08030v1
+2002-01-31,Electron impact excitation of helium-like oxygen up to n = 4 levels including radiation damping,"The primary X-ray diagnostic lines in He-like ions are mainly excited by
+electron impact from the ground level to the n = 2 levels, but at high
+temperatures n > 2 levels are also excited. In order to describe the atomic
+processes more completely collision strengths are computed for OVII including
+for the first time all of the following: (i) relativistic fine structure, (ii)
+levels up to the n = 4, and (iii) radiation damping of autoionizing resonances.
+The calculations are carried out using the Breit-Pauli R-matrix (BPRM) method
+with a 31-level eigenfunction expansion. Resonance structures in collision
+strengths are delineated in detail up to the n = 4 thresholds. For highly
+charged He-like ions radiation damping of autoionizing resonances is known to
+be significant. We investigate this effect in detail and find that while
+resonances are discernibly damped radiatively as the series limit n --> infty
+is approached from below, the overall effect on effective cross sections and
+rate coefficients is found to be very small. Collision strengths for the
+principal lines important in X-ray plasma diagnostics, w,x,y and z,
+corresponding to the 4 transitions to the ground level 1s^2 (^1S_0) <-- 1s2p
+(^1P^o_1), 1s2p (^3P^o_2), 1s2p (^3P^o_1), 1s2s (^3S_1), are explicitly shown.
+It is found that the effective collision strength of the forbidden z-line is up
+to a factor of 4 higher at T < 10^6 K than previous values. This is likely to
+be of considerable importance in the diagnostics of photoionized astrophysical
+plasmas. Significant differences are also found with previous works for several
+other transitions. This work is carried out as part of the Iron Project-RmaX
+Network.",0201535v1
+2015-10-10,Boundary layers and incompressible Navier-Stokes-Fourier limit of the Boltzmann Equation in Bounded Domain (I),"We establish the incompressible Navier-Stokes-Fourier limit for solutions to
+the Boltzmann equation with a general cut-off collision kernel in a bounded
+domain. Appropriately scaled families of DiPerna-Lions-(Mischler) renormalized
+solutions with Maxwell reflection boundary conditions are shown to have
+fluctuations that converge as the Knudsen number goes to zero. Every limit
+point is a weak solution to the Navier-Stokes-Fourier system with different
+types of boundary conditions depending on the ratio between the accommodation
+coefficient and the Knudsen number. The main new result of the paper is that
+this convergence is strong in the case of Dirichlet boundary condition. Indeed,
+we prove that the acoustic waves are damped immediately, namely they are damped
+in a boundary layer in time. This damping is due to the presence of viscous and
+kinetic boundary layers in space. As a consequence, we also justify the first
+correction to the infinitesimal Maxwellian that one obtains from the
+Chapman-Enskog expansion with Navier-Stokes scaling.
+  This extends the work of Golse and Saint-Raymond \cite{Go-Sai04, Go-Sai05}
+and Levermore and Masmoudi \cite{LM} to the case of a bounded domain. The case
+of a bounded domain was considered by Masmoudi and Saint-Raymond \cite{M-S} for
+linear Stokes-Fourier limit and Saint-Raymond \cite{SRM} for Navier-Stokes
+limit for hard potential kernels. Both \cite{M-S} and \cite{SRM} didn't study
+the damping of the acoustic waves. This paper extends the result of \cite{M-S}
+and \cite{SRM} to the nonlinear case and includes soft potential kernels. More
+importantly, for the Dirichlet boundary condition, this work strengthens the
+convergence so as to make the boundary layer visible. This answers an open
+problem proposed by Ukai \cite{Ukai}.",1510.02977v1
+2017-12-05,Harnessing Electrical Power from Vortex-Induced Vibration of a Circular Cylinder,"The generation of electrical power from Vortex-Induced Vibration (VIV) of a
+cylinder is investigated numerically. The cylinder is free to oscillate in the
+direction transverse to the incoming flow. The cylinder is attached to a magnet
+that can move along the axis of a coil made from conducting wire. The magnet
+and the coil together constitute a basic electrical generator. When the
+cylinder undergoes VIV, the motion of the magnet creates a voltage across the
+coil, which is connected to a resistive load. By Lenz's law, induced current in
+the coil applies a retarding force to the magnet. Effectively, the electrical
+generator applies a damping force on the cylinder with a spatially varying
+damping coefficient. For the initial investigation reported here, the Reynolds
+number is restricted to Re < 200, so that the flow is laminar and
+two-dimensional (2D). The incompressible 2D Navier-Stokes equations are solved
+using an extensively validated spectral-element based solver. The effects of
+the electromagnetic (EM) damping constant xi_m, coil dimensions (radius a,
+length L), and mass ratio on the electrical power extracted are quantified. It
+is found that there is an optimal value of xi_m (xi_opt) at which maximum
+electrical power is generated. As the radius or length of the coil is
+increased, the value of xi_opt is observed to increase. Although the maximum
+average power remains the same, a larger coil radius or length results in a
+more robust system in the sense that a relatively large amount of power can be
+extracted when xi_m is far from xi_opt, unlike the constant damping ratio case.
+The average power output is also a function of Reynolds number, primarily
+through the increased maximum oscillation amplitude that occurs with increased
+Reynolds number at least within the laminar range, although the general
+qualitative findings seem likely to carry across to high Reynolds number VIV.",1712.01588v1
+2020-02-14,Testing Physical Models for Cosmic Ray Transport Coefficients on Galactic Scales: Self-Confinement and Extrinsic Turbulence at GeV Energies,"The microphysics of ~GeV cosmic ray (CR) transport on galactic scales remain
+deeply uncertain, with almost all studies adopting simple prescriptions (e.g.
+constant-diffusivity). We explore different physically-motivated, anisotropic,
+dynamical CR transport scalings in high-resolution cosmological FIRE
+simulations of dwarf and ~$L_{\ast}$ galaxies where scattering rates vary with
+local plasma properties motivated by extrinsic turbulence (ET) or
+self-confinement (SC) scenarios, with varying assumptions about e.g. turbulent
+power spectra on un-resolved scales, Alfven-wave damping, etc. We
+self-consistently predict observables including $\gamma$-rays ($L_{\gamma}$),
+grammage, residence times, and CR energy densities to constrain the models. We
+demonstrate many non-linear dynamical effects (not captured in simpler models)
+tend to enhance confinement. For example, in multi-phase media, even allowing
+arbitrary fast transport in neutral gas does not substantially reduce CR
+residence times (or $L_{\gamma}$), as transport is rate-limited by the ionized
+WIM and 'inner CGM' gaseous halo ($10^{4}-10^{6}$ K gas within 10-30 kpc), and
+$L_{\gamma}$ can be dominated by trapping in small 'patches.' Most physical ET
+models contribute negligible scattering of ~1-10 GeV CRs, but it is crucial to
+account for anisotropy and damping (especially of fast modes) or else
+scattering rates would violate observations. We show that the most
+widely-assumed scalings for SC models produce excessive confinement by factors
+>100 in the WIM and inner CGM, where turbulent and Landau damping dominate.
+This suggests either a breakdown of quasi-linear theory used to derive the CR
+transport parameters in SC, or that other novel damping mechanisms dominate in
+intermediate-density ionized gas.",2002.06211v2
+2023-12-25,IMEX-RK methods for Landau-Lifshitz equation with arbitrary damping,"Magnetization dynamics in ferromagnetic materials is modeled by the
+Landau-Lifshitz (LL) equation, a nonlinear system of partial differential
+equations. Among the numerical approaches, semi-implicit schemes are widely
+used in the micromagnetics simulation, due to a nice compromise between
+accuracy and efficiency. At each time step, only a linear system needs to be
+solved and a projection is then applied to preserve the length of
+magnetization. However, this linear system contains variable coefficients and a
+non-symmetric structure, and thus an efficient linear solver is highly desired.
+If the damping parameter becomes large, it has been realized that efficient
+solvers are only available to a linear system with constant, symmetric, and
+positive definite (SPD) structure. In this work, based on the implicit-explicit
+Runge-Kutta (IMEX-RK) time discretization, we introduce an artificial damping
+term, which is treated implicitly. The remaining terms are treated explicitly.
+This strategy leads to a semi-implicit scheme with the following properties:
+(1) only a few linear system with constant and SPD structure needs to be solved
+at each time step; (2) it works for the LL equation with arbitrary damping
+parameter; (3) high-order accuracy can be obtained with high-order IMEX-RK time
+discretization. Numerically, second-order and third-order IMEX-RK methods are
+designed in both the 1-D and 3-D domains. A comparison with the backward
+differentiation formula scheme is undertaken, in terms of accuracy and
+efficiency. The robustness of both numerical methods is tested on the first
+benchmark problem from National Institute of Standards and Technology. The
+linearized stability estimate and optimal rate convergence analysis are
+provided for an alternate IMEX-RK2 numerical scheme as well.",2312.15654v1
+2020-07-21,Random walk of a massive quasiparticle in the phonon gas of an ultralow temperature superfluid,"We consider a 3D homogeneous superfluid at low temperature $T$ with 2 types
+of excitations, gapless phonons with a linear dispersion relation at low
+wavenumber, and gapped quasiparticles with a quadratic dispersion relation
+around extrema. We calculate the scattering amplitude of a phonon on a
+quasiparticle to leading order in $T$ for all subsonic quasiparticle
+velocities, with a $S$-matrix formalism between exact asymptotic states dressed
+by virtual phonons. We then characterize the erratic motion of the
+quasiparticle in the superfluid due to its unceasing collisions with thermal
+phonons through mean force $F(k)$, longitudinal and transverse $k$-dependent
+momentum diffusion coefficients, and spatial diffusion coefficient. At the
+minimum location $k_0$ of the dispersion relation, where the velocity vanishes,
+$F(k)$ varies linearly with velocity with an isotropic friction coefficient; if
+$k_0=0$, the momentum diffusion is also isotropic and $F(k_0)=0$; if $k_0>0$,
+it is not, and $F(k_0)$ is nonzero but subleading with respect to friction by
+one order in $T$. The velocity time correlation function, whose integral is the
+spatial diffusion coefficient, decays with the mean velocity damping rate if
+$k_0=0$; if $k_0>0$, it has a second exponential component, with an amplitude
+and a damping rate lower by a factor $\propto T$ (it is the velocity direction
+thermalization rate). We also characterize force and momentum diffusion close
+to the stability domain sonic edge. Our general expressions are expected to be
+exact to leading order in $T$. We illustrate them in the BCS approximation, for
+a fermionic quasiparticle (an unpaired fermion) in a superfluid of spin 1/2
+fermions, realisable with cold atoms in flat bottom traps. We also refute the
+statement of Lerch, Bartosch and Kopietz (2008), that there would be no
+fermionic quasiparticle in such a superfluid.",2007.10678v2
+1998-09-15,Solid friction at high sliding velocities: an explicit 3D dynamical SPH approach,"We present realistic 3D numerical simulations of elastic bodies sliding on
+top of each other in a regime of velocities ranging from meters to tens of
+meters per second using the so-called Smoothed Particle Hydrodynamics (SPH)
+method. Our investigations are restricted to regimes of pressure and roughness
+where only elastic deformations occur between asperities at the contact surface
+between the slider block and the substrate. In this regime, solid friction is
+due to the generation of vibrational radiations which are subsequently damped
+out. We study periodic commensurate and incommensurate asperities and various
+types of disordered surfaces. We report the evidence of a transition from zero
+(or non-measurable $\mu < 0.001$) friction to a finite friction as the normal
+pressure increases above about $10^6~Pa$. For larger normal pressures (up to
+$10^9~Pa$), we find a remarkably universal value for the friction coefficient
+$\mu \approx 0.06$, which is independent of the internal dissipation strength
+over three order of magnitudes, and independent of the detailled nature of the
+slider block-substrate interactions. We find that disorder may either decrease
+or increase $\mu$ due to the competition between two effects: disorder detunes
+the coherent vibrations of the asperties that occur in the periodic case,
+leading to weaker acoustic radiation and thus weaker damping. On the other
+hand, large disorder leads to stronger vibration amplitudes at local asperities
+and thus stronger damping. Our simulations have confirmed the existence of
+jumps over steps or asperities of the slider blocks occurring at the largest
+velocities studied ($10~m/s$). These jumps lead to chaotic motions similar to
+the bouncing-ball problem. We find a velocity strengthening with a doubling of
+the friction coefficient as the velocity increases from $1~m/s$ to $10~m/s$.",9809213v1
+2011-11-25,Application of a damped Locally Optimized Combination of Images method to the spectral characterization of faint companions using an Integral Field Spectrograph,"High-contrast imaging instruments are now being equipped with integral field
+spectrographs (IFS) to facilitate the detection and characterization of faint
+substellar companions. Algorithms currently envisioned to handle IFS data, such
+as the Locally Optimized Combination of Images (LOCI) algorithm, rely upon
+aggressive point-spread-function (PSF) subtraction, which is ideal for
+initially identifying companions but results in significantly biased photometry
+and spectroscopy due to unwanted mixing with residual starlight. This
+spectro-photometric issue is further complicated by the fact that algorithmic
+color response is a function of the companion's spectrum, making it difficult
+to calibrate the effects of the reduction without using iterations involving a
+series of injected synthetic companions. In this paper, we introduce a new PSF
+calibration method, which we call ""damped LOCI"", that seeks to alleviate these
+concerns. By modifying the cost function that determines the weighting
+coefficients used to construct PSF reference images, and also forcing those
+coefficients to be positive, it is possible to extract companion spectra with a
+precision that is set by calibration of the instrument response and
+transmission of the atmosphere, and not by post-processing. We demonstrate the
+utility of this approach using on-sky data obtained with the Project 1640 IFS
+at Palomar. Damped-LOCI does not require any iterations on the underlying
+spectral type of the companion, nor does it rely upon priors involving the
+chromatic and statistical properties of speckles. It is a general technique
+that can readily be applied to other current and planned instruments that
+employ IFS's.",1111.6102v1
+2024-03-04,Exploring Standing and Reflected Slow-mode Waves in Flaring Coronal Loops: A Parametric Study Using 2.5D MHD Modeling,"Recent observations of reflected propagating and standing slow-mode waves in
+hot flaring coronal loops have spurred our investigation into their underlying
+excitation and damping mechanisms. To understand these processes, we conduct
+2.5D magnetohydrodynamic (MHD) simulations using an arcade active region model
+that includes a hot and dense loop. Our simulations allow for in-depth
+parametric investigations complementing and expanding our previous 3D MHD
+modeling results. We excite these waves in two distinct models as motivated by
+observations from the SDO/AIA. Model 1 incorporates classical compressive
+viscosity coefficient, while Model 2 adopts a 10-times enhanced viscosity
+coefficient. We find that: (1) Our 2.5D MHD simulations reinforce previous
+conclusions derived from 1D and 3D MHD models that significantly enhanced
+viscosity is crucial for the rapid excitation of standing slow waves with
+damping times consistent with observations by Wang et al. (2015). (2) We
+uncover that nonlinearity in Model 1 delays the conversion of a reflected
+propagating wave into a standing wave. In contrast, Model 2 exhibits a much
+weak influence of nonlinearity. (3) Our results reveal that the transverse
+temperature structure holds more influence on wave behavior than the density
+structure. In Model 1, increased loop temperature contrast significantly
+enhances wave trapping within the structure, mitigating the impact of
+temperature-dependent viscous damping. Conversely, in Model 2, the impact of
+temperature structure on wave behavior weakens in comparison to the effect of
+viscosity. (4) Model 1 displays evident nonlinear coupling to the fast and kink
+magnetoacoustic waves and pronounced wave leakage into the corona. However,
+analyzing three observed wave events by SDO/AIA aligns with Model 2
+predictions, providing further support for the substantial viscosity increase.",2403.02464v1
+2021-02-09,Binet's factorial series and extensions to Laplace transforms,"We investigate a generalization of Binet's factorial series in the parameter
+$\alpha$ \[ \mu\left( z\right) =\sum_{m=1}^{\infty}\frac{b_{m}\left(
+\alpha\right) }{\prod_{k=0}^{m-1}(z+\alpha+k)}% \] due to Gilbert, for the
+Binet function \[ \mu\left( z\right) =\log\Gamma\left( z\right) -\left(
+z-\frac{1} {2}\right) \log z+z-\frac{1}{2}\log\left( 2\pi\right) \] After a
+review of the Binet function $\mu\left( z\right) $ and Gilbert's investigations
+of $\mu\left( z\right) $, several properties of the Binet polynomials
+$b_{m}\left( \alpha\right) $ are presented. We compare Gilbert's generalized
+factorial series with Stirling's asymptotic expansion and demonstrate by a
+numerical example that, with a same number of terms evaluated, the Gilbert
+generalized factorial series with an optimized value of $\alpha$ can beat the
+best possible accuracy of Stirling's expansion. Finally, we extend Binet's
+method to factorial series of Laplace transforms.",2102.04891v7
+2002-06-26,"General Formula for the Thermoelectric Transport Phenomena based on the Fermi Liquid Theory: Thermopower, Nernst Coefficient, and Thermal Conductivity","On the basis of the linear response transport theory, the general expressions
+for the thermoelectric transport coefficients, such as thermoelectric power
+(S), Nernst coefficient (\nu), and thermal conductivity (\kappa), are derived
+by using the Fermi liquid theory. The obtained expression is exact as for the
+most singular term in terms of 1/\gamma_k^* (\gamma_k^* being the quasiparticle
+damping rate). We utilize the Ward identities for the heat current which is
+derived by the local energy conservation law. Based on the derived expressions,
+we can calculate various thermoelectric transport coefficients within the
+framework of the Baym-Kadanoff type conserving approximation. Thus, the present
+expressions are very useful for studying the strongly correlated electrons such
+as high-Tc superconductors, organic metals, and heavy Fermion systems, where
+the current vertex corrections are expected to play important roles. By using
+the derived expression, we calculate the thermal conductivity \kappa in a
+free-dispersion model up to the second-order with respect to U. We find that it
+is slightly enhanced due to the vertex correction for the heat current,
+although the vertex correction for electron current makes the conductivity
+(\sigma) of this system diverge, reflecting the absence of the Umklapp process.",0206501v3
+2012-12-05,Stationary two-dimensional turbulence statistics using a Markovian forcing scheme,"In this study we investigate the statistics of two-dimensional stationary
+turbulence using a Markovian forcing scheme, which correlates the forcing
+process in the current time step to the previous time step according to a
+defined memory coefficient. In addition to the Markovian forcing mechanism, the
+hyperviscous dissipation mechanism for small scales and the Ekman friction type
+of linear damping mechanism for the large scales are included in the model. We
+examine the effects of various dissipation and forcing parameters on the
+turbulence statistics in both wave space and physical space. Our analysis
+includes the effects of the effective forcing scale, the bandwidth of the
+forcing, the memory correlation coefficient, and the forcing amplitude, along
+with the large scale friction and small scale dissipation coefficients. Scaling
+exponents of structure functions and energy spectra are calculated, and the
+role of the parameters associated with the Markovian forcing is discussed. We
+found that the scaling exponents are approximately invariant and show a
+universal behavior for the various forms of forcing schemes used. We found,
+however, that the final states strongly depend on the large scale friction
+mechanism considered. When the large scale friction mechanism is included in
+the model with a high friction coefficient, we demonstrate that the behavior is
+no longer universal. Our analysis also shows that the second-order vorticity
+structure function has an asymptotic scaling exponent for larger dissipation.
+Additionally, we confirmed that vorticity behaves as a passive scalar when the
+dissipation mechanism becomes less effective. Finally, although turbulence is
+not believed to have a separation of time scales in the dynamics of the
+velocity field, we conjectured that a separation of time scales exists in the
+dynamics of the energy spectrum.",1212.0916v1
+2023-06-12,Dynamics of the $O(4)$ critical point in QCD: critical pions and diffusion in Model G,"We present a detailed study of the finite momentum dynamics of the $O(4)$
+critical point of QCD, which lies in the dynamic universality class of Model G.
+The critical scaling of the model is analyzed in multiple dynamical channels.
+For instance, the finite momentum analysis allows us to precisely extract the
+pion dispersion curve below the critical point. The pion velocity is in
+striking agreement with the predictions relation and static universality. The
+pion damping rate and velocity are both consistent with the dynamical critical
+exponent $\zeta = 3/2$ of Model G. Similarly, although the critical amplitude
+for the diffusion coefficient of the conserved $O(4)$ charges is small, it is
+clearly visible both in the restored phase and with finite explicit symmetry
+breaking, and its dynamical scaling is again consistent with $\zeta=3/2$. We
+determine a new set of universal dynamical critical amplitude ratios relating
+the diffusion coefficient to a suitably defined order parameter relaxation
+time. We also show that in a finite volume simulation, the chiral condensate
+diffuses on the coset manifold in a manner consistent with dynamical scaling,
+and with a diffusion coefficient that is determined by the transport
+coefficients of hydrodynamic pions. Finally, the amplitude ratios (together
+with other non-universal amplitudes also reported here) compile all relevant
+information for further studies of Model G both in and out of equilibrium.",2306.06887v2
+2024-03-12,Cosmic Ray Feedback on Bi-stable ISM Turbulence,"Despite being energetically important, the effect of cosmic rays on the
+dynamics of the interstellar medium (ISM) is assumed to be negligible because
+the cosmic ray energy diffusion coefficient parallel to the magnetic field is
+relatively large. Using numerical simulations, we explore how variation of the
+cosmic ray diffusion coefficient as a function of gas temperature could impact
+the dynamics of the ISM. We create a two-zone model of cosmic ray transport,
+reflecting the strong damping of the small scale magnetic field fluctuations,
+which scatter the cosmic rays, in a gas with low ionization. The variable
+diffusion coefficient allows more cold gas to form. However, setting the
+diffusion coefficient at a critical value in the warm phase allows the cosmic
+rays to adjust the kinetic energy cascade. Specifically, we show the slope of
+the cascade changes for motion perpendicular to the mean magnetic field,
+whereas kinetic energy parallel to the magnetic field is reduced equally across
+inertial scales. We show that cosmic ray energization (or reacceleration) comes
+at the expense of total radiated energy generated during the formation of a
+cold cloud. We also show that our two-zone model of cosmic ray transport is
+capable of matching estimates of the grammage for some paths through the
+simulation, but full comparison of the grammage requires simulating turbulence
+in a larger volume.",2403.07976v1
+2023-10-11,High-speed photonic crystal modulator with non-volatile memory via structurally-engineered strain concentration in a piezo-MEMS platform,"Numerous applications in quantum and classical optics require scalable,
+high-speed modulators that cover visible-NIR wavelengths with low footprint,
+drive voltage (V) and power dissipation. A critical figure of merit for
+electro-optic (EO) modulators is the transmission change per voltage, dT/dV.
+Conventional approaches in wave-guided modulators seek to maximize dT/dV by the
+selection of a high EO coefficient or a longer light-material interaction, but
+are ultimately limited by nonlinear material properties and material losses,
+respectively. Optical and RF resonances can improve dT/dV, but introduce added
+challenges in terms of speed and spectral tuning, especially for high-Q
+photonic cavity resonances. Here, we introduce a cavity-based EO modulator to
+solve both trade-offs in a piezo-strained photonic crystal cavity. Our approach
+concentrates the displacement of a piezo-electric actuator of length L and a
+given piezoelectric coefficient into the PhCC, resulting in dT/dV proportional
+to L under fixed material loss. Secondly, we employ a material deformation that
+is programmable under a ""read-write"" protocol with a continuous, repeatable
+tuning range of 5 GHz and a maximum non-volatile excursion of 8 GHz. In
+telecom-band demonstrations, we measure a fundamental mode linewidth = 5.4 GHz,
+with voltage response 177 MHz/V corresponding to 40 GHz for voltage spanning
+-120 to 120 V, 3dB-modulation bandwidth of 3.2 MHz broadband DC-AC, and 142 MHz
+for resonant operation near 2.8 GHz operation, optical extinction down to
+min(log(T)) = -25 dB via Michelson-type interference, and an energy consumption
+down to 0.17 nW/GHz. The strain-enhancement methods presented here are
+applicable to study and control other strain-sensitive systems.",2310.07798v2
+2000-05-29,Entropy Production in a Persistent Random Walk,"We consider a one-dimensional persisent random walk viewed as a deterministic
+process with a form of time reversal symmetry. Particle reservoirs placed at
+both ends of the system induce a density current which drives the system out of
+equilibrium. The phase space distribution is singular in the stationary state
+and has a cumulative form expressed in terms of generalized Takagi functions.
+The entropy production rate is computed using the coarse-graining formalism of
+Gaspard, Gilbert and Dorfman. In the continuum limit, we show that the value of
+the entropy production rate is independent of the coarse-graining and agrees
+with the phenomenological entropy production rate of irreversible
+thermodynamics.",0005063v1
+2012-12-13,A convergent finite element approximation for the quasi-static Maxwell--Landau--Lifshitz--Gilbert equations,"We propose a $\theta$-linear scheme for the numerical solution of the
+quasi-static Maxwell-Landau-Lifshitz-Gilbert (MLLG) equations. Despite the
+strong nonlinearity of the Landau-Lifshitz-Gilbert equation, the proposed
+method results in a linear system at each time step. We prove that as the time
+and space steps tend to zero (with no further conditions when
+$\theta\in(1/2,1]$), the finite element solutions converge weakly to a weak
+solution of the MLLG equations. Numerical results are presented to show the
+applicability of the method.",1212.3369v1
+2013-09-28,Global Well-Posedness of the Landau-Lifshitz-Gilbert equation for initial data in Morrey space,"We establish the global well-posedness of the Landau-Lifshitz-Gilbert
+equation in $\mathbb R^n$ for any initial data ${\bf m}_0\in H^1_*(\mathbb
+R^n,\mathbb S^2)$ whose gradient belongs to the Morrey space $M^{2,2}(\mathbb
+R^n)$ with small norm $\displaystyle\|\nabla {\bf m}_0\|_{M^{2,2}(\mathbb
+R^n)}$. The method is based on priori estimates of a dissipative Schr\""odinger
+equation of Ginzburg-Landau types obtained from the Landau-Lifshitz-Gilbert
+equation by the moving frame technique.",1309.7426v1
+2016-10-26,Iterated Gilbert Mosaics and Poisson Tropical Plane Curves,"We propose an iterated version of the Gilbert model, which results in a
+sequence of random mosaics of the plane. We prove that under appropriate
+scaling, this sequence of mosaics converges to that obtained by a classical
+Poisson line process with explicit cylindrical measure. Our model arises from
+considerations on tropical plane curves, which are zeros of random tropical
+polynomials in two variables. In particular, the iterated Gilbert model
+convergence allows one to derive a scaling limit for Poisson tropical plane
+curves. Our work raises a number of open questions at the intersection of
+stochastic and tropical geometry.",1610.08533v1
+2017-05-29,Strong solvability of regularized stochastic Landau-Lifshitz-Gilbert equation,"We examine a stochastic Landau-Lifshitz-Gilbert equation based on an exchange
+energy functional containing second-order derivatives of the unknown field.
+Such regularizations are featured in advanced micromagnetic models recently
+introduced in connection with nanoscale topological solitons. We show that, in
+contrast to the classical stochastic Landau-Lifshitz-Gilbert equation based on
+the Dirichlet energy alone, the regularized equation is solvable in the
+stochastically strong sense. As a consequence it preserves the topology of the
+initial data, almost surely.",1705.10184v1
+2021-04-03,Improving the Gilbert-Varshamov Bound by Graph Spectral Method,"We improve Gilbert-Varshamov bound by graph spectral method. Gilbert graph
+$G_{q,n,d}$ is a graph with all vectors in $\mathbb{F}_q^n$ as vertices where
+two vertices are adjacent if their Hamming distance is less than $d$. In this
+paper, we calculate the eigenvalues and eigenvectors of $G_{q,n,d}$ using the
+properties of Cayley graph. The improved bound is associated with the minimum
+eigenvalue of the graph. Finally we give an algorithm to calculate the bound
+and linear codes which satisfy the bound.",2104.01403v3
+2000-05-10,Hydrodynamical Survey of First Overtone Cepheids,"A hydrodynamical survey of the pulsational properties of first overtone
+Galactic Cepheids is presented. The goal of this study is to reproduce their
+observed light- and radial velocity curves. The comparison between the models
+and the observations is made in a quantitative manner on the level of the
+Fourier coefficients. Purely radiative models fail to reproduce the observed
+features, but convective models give good agreement.
+  It is found that the sharp features in the Fourier coefficients are indeed
+caused by the P1/P4 = 2 resonance, despite the very large damping of the 4th
+overtone. For the adopted mass-luminosity relation the resonance center lies
+near a period of 4.2d +/- 0.2 as indicated by the observed radial velocity
+data, rather than near 3.2d as the light-curves suggest.",0005230v2
+2007-02-09,Bulk viscosity in kaon condensed matter,"We investigate the effect of $K^-$ condensed matter on bulk viscosity and
+r-mode instability in neutron stars. The bulk viscosity coefficient due to the
+non-leptonic process $n \rightleftharpoons p + K^-$ is studied here. In this
+connection, equations of state are constructed within the framework of
+relativistic field theoretical models where nucleon-nucleon and kaon-nucleon
+interactions are mediated by the exchange of scalar and vector mesons. We find
+that the bulk viscosity coefficient due to the non-leptonic weak process in the
+condensate is suppressed by several orders of magnitude. Consequently, kaon
+bulk viscosity may not damp the r-mode instability in neutron stars.",0702259v2
+2005-07-28,Theory of transverse spin dynamics in a polarized Fermi liquid and an itinerant ferromagnet,"The linear equations for transverse spin dynamics in a weakly polarized
+degenerate Fermi liquid with arbitrary relationship between temperature and
+polarization are derived from Landau-Silin phenomenological kinetic equation
+with general form of two-particle collision integral. Unlike the previous
+treatment where Fermi velocity and density of states have been taken as
+constants independent of polarization here we made derivation free from this
+assumption. The obtained equations are applicable for description of spin
+dynamics in paramagnetic Fermi liquid with finite polarization as well in an
+itinerant ferromagnet. In both cases transverse spin wave frequency is found to
+be proportional to the square of the wave vector with complex constant of
+proportionality (diffusion coefficient) such that the damping has a finite
+value at T=0. The polarization dependence of the diffusion coefficient is found
+to be different for a polarized Fermi liquid and for an itinerant ferromagnet.
+These conclusions are confirmed by derivation of transverse spin wave
+dispersion law in frame of field theoretical methods from the integral equation
+for the vortex function. It is shown that similar derivation taking into
+consideration the divergency of static transverse susceptibility also leads to
+the same attenuating spin wave spectrum.",0507675v1
+1993-12-02,Standard Model CP-violation and Baryon asymmetry,"Simply based on CP arguments, we argue against a Standard Model explanation
+of the baryon asymmetry of the universe in the presence of a first order phase
+transition. A CP-asymmetry is found in the reflection coefficients of quarks
+hitting the phase boundary created during the electroweak transition. The
+problem is analyzed both in an academic zero temperature case and in the
+realistic finite temperature one. The building blocks are similar in both
+cases: Kobayashi-Maskawa CP-violation, CP-even phases in the reflection
+coefficients of quarks, and physical transitions due to fermion self-energies.
+In both cases an effect is present at order $\alpha_W^2$ in rate. A standard
+GIM behaviour is found as intuitively expected. In the finite temperature case,
+a crucial role is played by the damping rate of quasi-particles in a hot
+plasma, which is a relevant scale together with $M_W$ and the temperature. The
+effect is many orders of magnitude below what observation requires, and
+indicates that non standard physics is indeed needed in the cosmological
+scenario.",9312215v1
+1996-04-17,Variation of transport coefficients for average fission dynamics with temperature and shape,"We study slow collective motion at finite thermal excitations on the basis of
+linear response theory applied to the locally harmonic approximation. The
+transport coefficients for average motion, friction \gamma, inertia M and the
+local stiffness C are computed along a fission path of Th-224 within a
+quasi-static picture. The inverse relaxation time \beta=\gamma/M and the
+effective damping rate \eta=\gamma/(2\sqrt{M|C|}) are found to increase with
+temperature, but do not change much with the collective variable. The values
+found for \eta and \beta as well as their behavior with temperature are in
+accord with experimental findings.",9604024v3
+2001-03-05,"Nuclear fission: The ""onset of dissipation"" from a microscopic point of view","Semi-analytical expressions are suggested for the temperature dependence of
+those combinations of transport coefficients which govern the fission process.
+This is based on experience with numerical calculations within the linear
+response approach and the locally harmonic approximation. A reduced version of
+the latter is seen to comply with Kramers' simplified picture of fission. It is
+argued that for variable inertia his formula has to be generalized, as already
+required by the need that for overdamped motion the inertia must not appear at
+all. This situation may already occur above T=2 MeV, where the rate is
+determined by the Smoluchowski equation. Consequently, comparison with
+experimental results do not give information on the effective damping rate, as
+often claimed, but on a special combination of local stiffnesses and the
+friction coefficient calculated at the barrier.",0103013v3
+2008-12-08,Partial integrability of the anharmonic oscillator,"We consider the anharmonic oscillator with an arbitrary-degree anharmonicity,
+a damping term and a forcing term, all coefficients being time-dependent: u"" +
+g_1(x) u' + g_2(x) u + g_3(x) u^n + g_4(x) = 0, n real. Its physical
+applications range from the atomic Thomas-Fermi model to Emden gas dynamics
+equilibria, the Duffing oscillator and numerous dynamical systems. The present
+work is an overview which includes and generalizes all previously known results
+of partial integrability of this oscillator. We give the most general two
+conditions on the coefficients under which a first integral of a particular
+type exists. A natural interpretation is given for the two conditions. We
+compare these two conditions with those provided by the Painleve' analysis.",0812.1451v1
+2010-11-29,Viscous lock-exchange in rectangular channels,"In a viscous lock-exchange gravity current, which describes the reciprocal
+exchange of two fluids of different densities in a horizontal channel, the
+front between two Newtonian fluids spreads as the square root of time. The
+resulting diffusion coefficient reflects the competition between the buoyancy
+driving effect and the viscous damping, and depends on the geometry of the
+channel. This lock-exchange diffusion coefficient has already been computed for
+a porous medium, a 2D Stokes flow between two parallel horizontal boundaries
+separated by a vertical height, H, and, recently, for a cylindrical tube. In
+the present paper, we calculate it, analytically, for a rectangular channel
+(horizontal thickness b, vertical height, H) of any aspect ratio (H/b) and
+compare our results with experiments in horizontal rectangular channels for a
+wide range of aspect ratios (1/10-10). We also discuss the 2D Stokes-Darcy
+model for flows in Hele-Shaw cells and show that it leads to a rather good
+approximation, when an appropriate Brinkman correction is used.",1011.6262v1
+2011-02-15,Decay of energy and suppression of Fermi acceleration in a dissipative driven stadium-like billiard,"The behavior of the average energy for an ensemble of non-interacting
+particles is studied using scaling arguments in a dissipative time-dependent
+stadium-like billiard. The dynamics of the system is described by a four
+dimensional nonlinear mapping. The dissipation is introduced via inelastic
+collisions between the particles and the moving boundary. For different
+combinations of initial velocities and damping coefficients, the long time
+dynamics of the particles leads them to reach different states of final energy
+and to visit different attractors, which change as the dissipation is varied.
+The decay of the average energy of the particles, which is observed for a large
+range of restitution coefficients and different initial velocities, is
+described using scaling arguments. Since this system exhibits unlimited energy
+growth in the absence of dissipation, our results for the dissipative case give
+support to the principle that Fermi acceleration seem not to be a structurally
+stable phenomenon.",1102.3139v4
+2012-05-31,Spin diffusion of lattice fermions in one dimension,"We study long-time spin diffusion of harmonically trapped lattice fermions in
+one dimension. Combining thermodynamic Bethe ansatz approach and local density
+approximation, we calculate spin current and spin diffusion coefficient driven
+by the population imbalance. We find spin current is driven by susceptibility
+effects rather than typical diffusion where magnetization would transport from
+regions of high magnetization to low. As expected, spin transport is zero
+through insulating regions and are only present in the metallic regions. In the
+weak coupling limit, the local spin diffusion coefficient shows maxima at all
+the insulating regions. Further, we estimate damping rate of diffusion modes in
+the weak coupling limit within the lower metallic portion of the cloud. The
+predicted spin current pattern can be probed via currently available
+experimental techniques.",1205.7019v2
+2012-11-15,A localized orthogonal decomposition method for semi-linear elliptic problems,"In this paper we propose and analyze a new Multiscale Method for solving
+semi-linear elliptic problems with heterogeneous and highly variable
+coefficient functions. For this purpose we construct a generalized finite
+element basis that spans a low dimensional multiscale space. The basis is
+assembled by performing localized linear fine-scale computations in small
+patches that have a diameter of order H |log H| where H is the coarse mesh
+size. Without any assumptions on the type of the oscillations in the
+coefficients, we give a rigorous proof for a linear convergence of the H1-error
+with respect to the coarse mesh size. To solve the arising equations, we
+propose an algorithm that is based on a damped Newton scheme in the multiscale
+space.",1211.3551v2
+2014-11-27,Transport coefficients in superfluid neutron stars,"We study the shear and bulk viscosity coefficients as well as the thermal
+conductivity as arising from the collisions among phonons in superfluid neutron
+stars. We use effective field theory techniques to extract the allowed phonon
+collisional processes, written as a function of the equation of state and the
+gap of the system. The shear viscosity due to phonon scattering is compared to
+calculations of that coming from electron collisions. We also comment on the
+possible consequences for r-mode damping in superfluid neutron stars. Moreover,
+we find that phonon collisions give the leading contribution to the bulk
+viscosities in the core of the neutron stars. We finally obtain a
+temperature-independent thermal conductivity from phonon collisions and compare
+it with the electron-muon thermal conductivity in superfluid neutron stars.",1411.7622v1
+2015-02-19,"Nonequilibrium inhomogeneous steady state distribution in disordered, mean-field rotator systems","We present a novel method to compute the phase space distribution in the
+nonequilibrium stationary state of a wide class of mean-field systems involving
+rotators subject to quenched disordered external drive and dissipation. The
+method involves a series expansion of the stationary distribution in inverse of
+the damping coefficient; the expansion coefficients satisfy recursion relations
+whose solution requires computing a sparse matrix, making numerical evaluation
+simple and efficient. We illustrate our method for the paradigmatic Kuramoto
+model of spontaneous collective synchronization and for its two mode
+generalization, in presence of noise and inertia, and demonstrate an excellent
+agreement between simulations and theory for the phase space distribution.",1502.05559v2
+2016-06-17,Unveiling the scattering behavior of small spheres,"A classical way for exploring the scattering behavior of a small sphere is to
+approximate Mie coefficients with a Taylor series expansion. This ansatz
+delivered a plethora of insightful results, mostly for small spheres supporting
+localized plasmonic resonances. However, many scattering aspects are still
+uncharted, especially with regards to magnetic resonances. Here, an alternative
+system ansatz is proposed based on the Pad\'e approximants for the Mie
+coefficients. The result reveal the existence of a self-regulating radiative
+damping mechanism for the first magnetic resonance and new general resonating
+aspects for the higher order multipoles. Hence, a systematic way of exploring
+the scattering behavior is introduced, sharpening our understanding about the
+sphere's scattering behavior and its emergent functionalities.",1606.05523v4
+2016-08-08,Simulations of Energetic Particles Interacting with Nonlinear Anisotropic Dynamical Turbulence,"We investigate test-particle diffusion in dynamical turbulence based on a
+numerical approach presented before. For the turbulence we employ the nonlinear
+anisotropic dynamical turbulence model which takes into account wave
+propagation effects as well as damping effects. We compute numerically
+diffusion coefficients of energetic particles along and across the mean
+magnetic field. We focus on turbulence and particle parameters which should be
+relevant for the solar system and compare our findings with different
+interplanetary observations. We vary different parameters such as the
+dissipation range spectral index, the ratio of the turbulence bendover scales,
+and the magnetic field strength in order to explore the relevance of the
+different parameters. We show that the bendover scales as well as the magnetic
+field ratio have a strong influence on diffusion coefficients whereas the
+influence of the dissipation range spectral index is weak. The best agreement
+with solar wind observations can be found for equal bendover scales and a
+magnetic field ratio of $\delta$B/B0 = 0.75.",1609.05226v1
+2017-02-06,General Scattering Characteristics of Resonant Core-Shell Spheres,"This article presents and discusses the general features and aspects
+regarding the electromagnetic scattering by a small core-shell plasmonic
+sphere. First, the thickness effects on the plasmonic resonances are presented
+in the electrostatic (Rayleigh) limit, utilizing the MacLaurin expansion of the
+Mie coefficients of hollow scatterers. Several aspects regarding the core
+effects are given, illustrating the enabling mechanisms and peculiarities of
+its resonant scattering response on it electrostatic limit. The electrodynamic
+aspects of the scattering process are revealed through the newly introduced
+Pad\'e expansion of the Mie coefficients. Additionally we expose how the core
+material affects the dynamic mechanisms, such as the dynamic depolarization and
+radiative damping. The described method can be expanded for other type of
+resonances and canonical shapes, while the general characteristics presented
+here are expected to stimulate further studies regarding the functionalities of
+the core-shell scatterers.",1702.01620v2
+2017-07-10,Model Identification and Controller Parameter Optimization for an Autopilot Design for Autonomous Underwater Vehicles,"Nowadays an accurate modeling of the system to be controlled is essential for
+reliable autopilot. This paper presents a non-linear model of the autonomous
+underwater vehicle 'CWolf'. Matrices and the corresponding coefficients
+generate a parameterized representation for added mass, Coriolis and
+centripetal forces, damping, gravity and buoyancy, using the equations of
+motion, for all six degrees of freedom. The determination of actuator behaviour
+by surge tests allows the conversion of propeller revolutions to the respective
+forces and moments. Based on geometric approximations, the coefficients of the
+model can be specified by optimization algorithms in 'open loop' sea trials.
+The realistic model is the basis for the subsequent design of the autopilot.
+The reference variables used in the four decoupled adaptive PID controllers for
+surge, heading, pitch and heave are provided a 'Line of Sight' - guidance
+system. A constraint criteria optimization determines the required controller
+parameters. The verification by 'closed loop' sea trials ensures the results.",1707.02767v1
+2017-08-06,Dynamics and locomotion of flexible foils in a frictional environment,"Over the past few decades, oscillating flexible foils have been used to study
+the physics of organismal propulsion in different fluid environments. Here we
+extend this work to a study of flexible foils in a frictional environment. When
+the foil is oscillated by heaving at one end but not allowed to locomote
+freely, the dynamics change from periodic to non-periodic and chaotic as the
+heaving amplitude is increased or the bending rigidity is decreased. For
+friction coefficients lying in a certain range, the transition passes through a
+sequence of $N$-periodic and asymmetric states before reaching chaotic
+dynamics. Resonant peaks are damped and shifted by friction and large heaving
+amplitudes, leading to bistable states.
+  When the foil is allowed to locomote freely, the horizontal motion smoothes
+the resonant behaviors. For moderate frictional coefficients, steady but slow
+locomotion is obtained. For large transverse friction and small tangential
+friction corresponding to wheeled snake robots, faster locomotion is obtained.
+Traveling wave motions arise spontaneously, and and move with horizontal speed
+that scales as transverse friction to the 1/4 power and input power that scales
+as transverse friction to the 5/12 power. These scalings are consistent with a
+boundary layer form of the solutions near the foil's leading edge.",1708.01827v1
+2017-09-19,On well-posedness of Ericksen-Leslie's hyperbolic incompressible liquid crystal model,"We study the Ericksen-Leslie's hyperbolic incompressible liquid crystal
+model. Under some constraints on the Leslie coefficients which ensure the basic
+energy law is dissipative, we prove the local-in-time existence and uniqueness
+of the classical solution to the system with finite initial energy.
+Furthermore, with an additional assumption on the coefficients which provides a
+damping effect, and the smallness of the initial energy, the unique global
+classical solution can be established.",1709.06370v3
+2017-09-19,Higher-order Fermi-liquid corrections for an Anderson impurity away from half-filling,"We study the higher-order Fermi-liquid relations of Kondo systems for
+arbitrary impurity-electron fillings, extending the many-body quantum
+theoretical approach of Yamada-Yosida. It includes partly a microscopic
+clarification of the related achievements based on Nozi\`{e}res'
+phenomenological description: Filippone, Moca, von Delft, and Mora [Phys.\
+Rev.\ B {\bf 95}, 165404 (2017)]. In our formulation, the Fermi-liquid
+parameters such as the quasi-particle energy, damping, and transport
+coefficients are related to each other through the total vertex
+$\Gamma_{\sigma\sigma';\sigma'\sigma} (\omega, \omega'; \omega', \omega)$,
+which may be regarded as a generalized Landau quasi-particle interaction. We
+obtain exactly this function up to linear order with respect to the frequencies
+$\omega$ and $\omega'$ using the anti-symmetry and analytic properties. The
+coefficients acquire additional contributions of three-body fluctuations away
+from half-filling through the non-linear susceptibilities. We also apply the
+formulation to non-equilibrium transport through a quantum dot, and clarify how
+the zero-bias peak evolves in a magnetic field.",1709.06385v2
+2019-02-06,Solar energetic particle propagation in wave turbulence and the possibility of wave generation,"A complete theory for the complex interaction between solar energetic
+particles and the turbulent interplanetary magnetic field remains elusive. In
+this work we aim to contribute towards such a theory by modelling the
+propagation of solar energetic particle electrons in plasma wave turbulence. We
+specify a background turbulence spectrum, as constrained through observations,
+calculate the transport coefficients from first principles, and simulate the
+propagation of these electrons in the inner heliosphere. We have also, for the
+first time, included dynamical effects into the perpendicular diffusion
+coefficient. We show that such a ""physics-first"" approach can lead to
+reasonable results, when compared qualitatively to observations. In addition,
+we include the effect of wave growth/damping due to streaming electrons and
+show that these particles can significantly alter the turbulence levels close
+to the Sun for the largest events.",1902.02038v1
+2019-02-20,Influence of Physical Properties of Hockey Stick Blade on Shots,"Parameters of a shot of an ice hockey player are mostly determined by the
+capabilities of the player and the physical properties of the stick used. To
+reach better performance, every hockey player uses also a hockey tape for an
+adjustment of the stick blade, that changes both the damping properties as well
+as the friction coefficient of the blade surface. To show the unexpected extent
+to which these physical properties of the blade affect the shot, we compared
+two types of blade cover: traditional tape (rolled onto the blade) and a blade
+sticker that adheres to both sides of the hockey stick blade. We analysed
+high-speed recordings of two types of shots by 13 players, ranging from
+amateurs and junior players to NHL superstars. The two covers differ greatly in
+friction coefficient and stiffness, which results in significantly (more than
+$99\%$ confidence) greater speed, rotation and energy when using the stiffer
+and rougher sticker.",1903.02635v2
+2020-07-30,A diffusive origin for the cosmic-ray spectral hardening reveals signatures of a nearbysource in the leptons and protons data,"In this work we aim at reproducing, simultaneously, the spectral feature at
+$\sim 10 \, \mathrm{TeV}$ in the cosmic-ray proton spectrum, recently reported
+by the DAMPE Collaboration, together with the spectral break at $\sim 1 \,
+\mathrm{TeV}$ measured by H.E.S.S. in the lepton spectrum. Those features are
+interpreted as signatures of one nearby hidden cosmic-ray accelerator. We show
+that this interpretation is consistent with the dipole-anisotropy data as long
+as the rigidity scaling of the diffusion coefficient features a hardening at
+$\sim 200 \, \mathrm{GV}$, as suggested by the light-nuclei data measured with
+high accuracy by the AMS-02 Collaboration. Such rigidity-dependent diffusion
+coefficient is applied consistently to the large-scale diffuse cosmic-ray sea
+as well as to the particles injected by the nearby source.",2007.15321v2
+2020-08-25,Stability results of coupled wave models with locally memory in a past history framework via non smooth coefficients on the interface,"In this paper, we investigate the stabilization of a locally coupled wave
+equations with local viscoelastic damping of past history type acting only in
+one equation via non smooth coefficients. First, using a general criteria of
+Arendt-Batty, we prove the strong stability of our system. Second, using a
+frequency domain approach combined with the multiplier method, we establish the
+exponential stability of the solution if and only if the two waves have the
+same speed of propagation. In case of different speed propagation, we prove
+that the energy of our system decays polynomially with rate 1/t. Finally, we
+show the lack of exponential stability if the speeds of wave propagation are
+different.",2008.11596v1
+2021-04-24,Convex optimization via inertial algorithms with vanishing Tikhonov regularization: fast convergence to the minimum norm solution,"In a Hilbertian framework, for the minimization of a general convex
+differentiable function $f$, we introduce new inertial dynamics and algorithms
+that generate trajectories and iterates that converge fastly towards the
+minimizer of $f$ with minimum norm. Our study is based on the non-autonomous
+version of the Polyak heavy ball method, which, at time $t$, is associated with
+the strongly convex function obtained by adding to $f$ a Tikhonov
+regularization term with vanishing coefficient $\epsilon(t)$. In this dynamic,
+the damping coefficient is proportional to the square root of the Tikhonov
+regularization parameter $\epsilon(t)$. By adjusting the speed of convergence
+of $\epsilon(t)$ towards zero, we will obtain both rapid convergence towards
+the infimal value of $f$, and the strong convergence of the trajectories
+towards the element of minimum norm of the set of minimizers of $f$. In
+particular, we obtain an improved version of the dynamic of Su-Boyd-Cand\`es
+for the accelerated gradient method of Nesterov. This study naturally leads to
+corresponding first-order algorithms obtained by temporal discretization. In
+the case of a proper lower semicontinuous and convex function $f$, we study the
+proximal algorithms in detail, and show that they benefit from similar
+properties.",2104.11987v1
+2021-08-13,Topology optimization for acoustic structures considering viscous and thermal boundary layers using a sequential linearized Navier-Stokes model,"This study proposes a level set-based topology optimization method for
+designing acoustic structures with viscous and thermal boundary layers in
+perspective. Acoustic waves propagating in a narrow channel are damped by
+viscous and thermal boundary layers. To estimate these viscothermal effects, we
+first introduce a sequential linearized Navier-Stokes model based on three
+weakly coupled Helmholtz equations for viscous, thermal, and acoustic pressure
+fields. Then, the optimization problem is formulated, where a sound-absorbing
+structure comprising air and an isothermal rigid medium is targeted, and its
+sound absorption coefficient is set as an objective function. The adjoint
+variable method and the concept of the topological derivative are used to
+approximately obtain design sensitivity. A level set-based topology
+optimization method is used to solve the optimization problem. Two-dimensional
+numerical examples are provided to support the validity of the proposed method.
+Moreover, the mechanisms that lead to the high absorption coefficient of the
+optimized design are discussed.",2108.06116v2
+2021-10-12,Computing semigroups with error control,"We develop an algorithm that computes strongly continuous semigroups on
+infinite-dimensional Hilbert spaces with explicit error control. Given a
+generator $A$, a time $t>0$, an arbitrary initial vector $u_0$ and an error
+tolerance $\epsilon>0$, the algorithm computes $\exp(tA)u_0$ with error bounded
+by $\epsilon$. The algorithm is based on a combination of a regularized
+functional calculus, suitable contour quadrature rules, and the adaptive
+computation of resolvents in infinite dimensions. As a particular case, we show
+that it is possible, even when only allowing pointwise evaluation of
+coefficients, to compute, with error control, semigroups on the unbounded
+domain $L^2(\mathbb{R}^d)$ that are generated by partial differential operators
+with polynomially bounded coefficients of locally bounded total variation. For
+analytic semigroups (and more general Laplace transform inversion), we provide
+a quadrature rule whose error decreases like $\exp(-cN/\log(N))$ for $N$
+quadrature points, that remains stable as $N\rightarrow\infty$, and which is
+also suitable for infinite-dimensional operators. Numerical examples are given,
+including: Schr\""odinger and wave equations on the aperiodic Ammann--Beenker
+tiling, complex perturbed fractional diffusion equations on $L^2(\mathbb{R})$,
+and damped Euler--Bernoulli beam equations.",2110.06350v1
+2021-10-16,"Global well-posedness, stability and instability for the non-viscous Oldroyd-B model","In this paper we consider the 3-dimensional incompressible Oldroyd-B model.
+First, we establish two results of the global existence for different kinds of
+the coupling coefficient $k$. Then, we prove that the solutions $(u,\tau)$ are
+globally steady when $k^m\rightarrow k>0$, though $(u,\tau)$ corresponds to
+different decays for different kinds of $k>0~$. Finally, we show that the
+energy of $u(t,x)$ will have a jump when $k\rightarrow 0$ in large time, which
+implies a non-steady phenomenon. In a word, we find an interesting physical
+phenomenon of \eqref{1} such that smaller coupling coefficient $k$ will have a
+better impact for the energy dissipation of $(u,\tau)$, but $k$ can't be too
+small to zero, or the dissipation will vanish instantly. While the damping term
+$\tau$ and $\mathbb{D}u$ always bring the well impact for the energy
+dissipation.",2110.08475v1
+2021-11-01,Dissipative superfluid relativistic magnetohydrodynamics of a multicomponent fluid: the combined effect of particle diffusion and vortices,"We formulate dissipative magnetohydrodynamic equations for finite-temperature
+superfluid and superconducting charged relativistic mixtures, taking into
+account the effects of particle diffusion and possible presence of
+Feynman-Onsager and/or Abrikosov vortices in the system. The equations depend
+on a number of phenomenological transport coefficients, which describe, in
+particular, relative motions of different particle species and their
+interaction with vortices. We demonstrate how to relate these transport
+coefficients to the mutual friction parameters and momentum transfer rates
+arising in the microscopic theory. The resulting equations can be used to
+study, in a unified and coherent way, a very wide range of phenomena associated
+with dynamical processes in neutron stars, e.g., the magnetothermal evolution,
+stellar oscillations and damping, as well as development and suppression of
+various hydrodynamic instabilities in neutron stars.",2111.00999v1
+2021-11-11,Quasinormal modes of charged black holes with corrections from nonlinear electrodynamics,"We study quasinormal modes related to gravitational and electromagnetic
+perturbations of spherically symmetric charged black holes in nonlinear
+electrodynamics. Beyond the linear Maxwell electrodynamics, we consider a class
+of Lagrangian with higher-order corrections written by the electromagnetic
+field strength and its Hodge dual with arbitrary coefficients, and we
+parametrize the corrections for quasinormal frequencies in terms of the
+coefficients. It is confirmed that the isospectrality of quasinormal modes
+under parity is generally violated due to nonlinear electrodynamics. As
+applications, the corrections for quasinormal frequencies in Euler-Heisenberg
+and Born-Infeld electrodynamics are calculated, then it is clarified that the
+nonlinear effects act to lengthen the oscillation period and enhance the
+damping rate of the quasinormal modes.",2111.06273v2
+2022-06-29,Strongly coupled quantum Otto cycle with single qubit bath,"We discuss a model of a closed quantum evolution of two-qubits where the
+joint Hamiltonian is so chosen that one of the qubits acts as a bath and
+thermalize the other qubit which is acting as the system. The corresponding
+exact master equation for the system is derived. Interestingly, for a specific
+choice of parameters the master equation takes the
+Gorini-Kossakowski-Lindblad-Sudarshan (GKLS) form with constant coefficients,
+representing pumping and damping of a single qubit system. Based on this model
+we construct an Otto cycle connected to a single qubit bath and study its
+thermodynamic properties. Our analysis goes beyond the conventional weak
+coupling scenario and illustrates the effects of finite bath including
+non-Markovianity. We find closed form expressions for efficiency (coefficient
+of performance), power (cooling power) for heat engine regime (refrigerator
+regime) for different modifications of the joint Hamiltonian.",2206.14751v1
+2022-08-29,Benchmarking magnetized three-wave coupling for laser backscattering: Analytic solutions and kinetic simulations,"Understanding magnetized laser-plasma interactions is important for
+controlling magneto-inertial fusion experiments and developing magnetically
+assisted radiation and particle sources. In the long-pulse regime, interactions
+are dominated by coherent three-wave interactions, whose nonlinear coupling
+coefficients become known only recently when waves propagate at oblique angles
+with the magnetic field. In this paper, backscattering coupling coefficients
+predicted by warm-fluid theory is benchmarked using particle-in-cell
+simulations in one spatial dimension, and excellent agreements are found for a
+wide range of plasma temperatures, magnetic field strengths, and laser
+propagation angles, when the interactions are mediated by electron-dominant
+hybrid waves. Systematic comparisons between theory and simulations are made
+possible by a rigorous protocol: On the theory side, the initial boundary value
+problem of linearized three-wave equations is solved, and the transient-time
+solutions allow effects of growth and damping to be distinguished. On the
+simulation side, parameters are carefully chosen and calibration runs are
+performed to ensure that stimulated runs are well controlled. Fitting
+simulation data to analytical solutions yields numerical growth rates, which
+match theory predictions within error bars. Although warm-fluid theory is found
+to be valid for a wide parameter range, genuine kinetic effects have also been
+observed.",2208.13832v2
+2022-09-07,Acoustic attenuation in magnetic insulator films: effects of magnon polaron formation,"A magnon and a phonon are the quanta of spin wave and lattice wave,
+respectively, and they can hybridize into a magnon polaron when their
+frequencies and wavenumbers match close enough the values at the exceptional
+point. Guided by an analytically calculated magnon polaron dispersion,
+dynamical phase-field simulations are performed to investigate the effects of
+magnon polaron formation on the attenuation of a bulk acoustic wave in a
+magnetic insulator film. It is shown that a stronger magnon-phonon coupling
+leads to a larger attenuation. The simulations also demonstrate the existence
+of a minimum magnon-phonon interaction time required for the magnon polaron
+formation, which is found to decrease with the magnetoelastic coupling
+coefficient but increase with the magnetic damping coefficient. These results
+deepen the understanding of the mechanisms of acoustic attenuation in magnetic
+crystals and provide insights into the design of new-concept spin interconnects
+that operate based on acoustically driven magnon propagation.",2209.03481v2
+2023-02-27,Diagonal State Space Augmented Transformers for Speech Recognition,"We improve on the popular conformer architecture by replacing the depthwise
+temporal convolutions with diagonal state space (DSS) models. DSS is a recently
+introduced variant of linear RNNs obtained by discretizing a linear dynamical
+system with a diagonal state transition matrix. DSS layers project the input
+sequence onto a space of orthogonal polynomials where the choice of basis
+functions, metric and support is controlled by the eigenvalues of the
+transition matrix. We compare neural transducers with either conformer or our
+proposed DSS-augmented transformer (DSSformer) encoders on three public
+corpora: Switchboard English conversational telephone speech 300 hours,
+Switchboard+Fisher 2000 hours, and a spoken archive of holocaust survivor
+testimonials called MALACH 176 hours. On Switchboard 300/2000 hours, we reach a
+single model performance of 8.9%/6.7% WER on the combined test set of the Hub5
+2000 evaluation, respectively, and on MALACH we improve the WER by 7% relative
+over the previous best published result. In addition, we present empirical
+evidence suggesting that DSS layers learn damped Fourier basis functions where
+the attenuation coefficients are layer specific whereas the frequency
+coefficients converge to almost identical linearly-spaced values across all
+layers.",2302.14120v1
+2023-03-22,Invariants for time-dependent Hamiltonian systems,"An exact invariant is derived for $n$-degree-of-freedom Hamiltonian systems
+with general time-dependent potentials. The invariant is worked out in two
+equivalent ways. In the first approach, we define a special {\it Ansatz\/} for
+the invariant and determine its time-dependent coefficients. In the second
+approach, we perform a two-step canonical transformation of the initially
+time-dependent Hamiltonian to a time-independent one. The invariant is found to
+contain a function of time $f_{2}(t)$, defined as a solution of a linear
+third-order differential equation whose coefficients depend in general on the
+explicitly known configuration space trajectory that follows from the system's
+time evolution. It is shown that the invariant can be interpreted as the time
+integral of an energy balance equation. Our result is applied to a
+one-dimensional, time-dependent, damped non-linear oscillator, and to a
+three-dimensional system of Coulomb-interacting particles that are confined in
+a time-dependent quadratic external potential. We finally show that our results
+can be used to assess the accuracy of numerical simulations of time-dependent
+Hamiltonian systems.",2303.12746v1
+2023-04-25,Room dimensions and absorption inference from room transfer function via machine learning,"The inference of the absorption configuration of an existing room solely
+using acoustic signals can be challenging. This research presents two methods
+for estimating the room dimensions and frequency-dependent absorption
+coefficients using room transfer functions. The first method, a knowledge-based
+approach, calculates the room dimensions through damped resonant frequencies of
+the room. The second method, a machine learning approach, employs multi-task
+convolutional neural networks for inferring the room dimensions and
+frequency-dependent absorption coefficients of each surface. The study shows
+that accurate wave-based simulation data can be used to train neural networks
+for real-world measurements and demonstrates a potential for this algorithm to
+be used to estimate the boundary input data for room acoustic simulations. The
+proposed methods can be a valuable tool for room acoustic simulations during
+acoustic renovation or intervention projects, as they enable to infer the room
+geometry and absorption conditions with reasonably small data requirements.",2304.12993v1
+2023-06-19,Reciprocal hydrodynamic response estimation in a random spreading sea,"Direct estimation of the hydrodynamic response of an offshore structure in a
+random spreading sea can lead to large computational costs. In this paper the
+actual spreading sea is replaced by an idealised diffuse wave field and the
+diffuse field reciprocity (DFR) relationship is derived analytically and
+verified against diffraction analysis for offshore application. The DFR
+approach provides an analytical expression for the estimation of the wave
+loading spectrum in a spreading sea. It is very efficient because only the
+added damping coefficients are required. Furthermore, if normalised to the peak
+amplitude of a spreading sea, an upper bound response can be obtained using the
+reciprocal approach. And this is demonstrated using a spar type floating wind
+turbine. Given that the hydrodynamic coefficients are routine outputs for
+offshore structural design, engineers would obtain the upper bound response
+without additional computational cost using this new approach.",2306.11058v1
+2023-09-11,Design of a Freely Rotating Wind Tunnel Test Bench for Measurements of Dynamic Coefficients,"The needs to improve performances of artillery projectiles require accurate
+aerodynamic investigation methods. The aerodynamic design of a projectile
+usually starts from numerical analyses, mostly including semiempirical methods
+and/or Computational Fluid Dynamics (CFD), up to experimental techniques
+composed of wind-tunnel measurements or free-flight validations. In the frame,
+the present paper proposes a dedicated measurement methodology able to
+simultaneously determine the stability derivative C m$\alpha$ and the pitch
+damping coefficient sum Cmq + Cm$\alpha$ in a wind tunnel by means of a single
+and almost non-intrusive metrological setup called MiRo. This method is based
+on the stereovision principle and a three-axis freely-rotating mechanical test
+bench. In order to assess the reliability, repeatability and accuracy of this
+technique, the MiRo wind tunnel measurements are compared to other sources like
+aerodynamic balance measurements, alternative wind tunnel measurements, Ludwieg
+tube measurements, free-flight measurements and CFD simulations.",2309.05302v1
+2006-02-20,Fluctuation theorem applied to the Nosé-Hoover thermostated Lorentz gas,"We present numerical evidence supporting the validity of the Gallavotti-Cohen
+Fluctuation Theorem applied to the driven Lorentz gas with Nos\'e-Hoover
+thermostating. It is moreover argued that the asymptotic form of the
+fluctuation formula is independent of the amplitude of the driving force, in
+the limit where it is small.",0602458v1
+1997-12-28,Model-independent $\tan β$ bounds in the MSSM,"We demonstrate, through the study of the one-loop effective potential in the
+MSSM, the existence of fully model-independent lower and upper theoretical
+bounds on $\tan \beta$. We give their general analytic form and illustrate some
+of their implications.",9712529v1
+2006-12-26,Very Light Gravitino Dark Matter,"We address the question of dark matter in the context of gauge mediated
+supersymmetry breaking models. In contrast with mSUGRA scenarios, the messenger
+of the susy breaking to the visible sector can play an important role allowing
+a relic gravitino in the $\sim {keV}$ to $10 {MeV}$ mass range to account for
+the cold dark matter in the Universe.",0612331v1
+2004-09-15,Characterizing rigid simplicial actions on trees,"We extend Forester's rigidity theorem so as to give a complete
+characterization of rigid group actions on trees (an action is rigid if it is
+the only reduced action in its deformation space, in particular it is invariant
+under automorphisms preserving the set of elliptic subgroups).",0409245v1
+2005-12-14,Efficient Construction of Photonic Quantum Computational Clusters,"We demonstrate a method of creating photonic two-dimensional cluster states
+that is considerably more efficient than previously proposed approaches. Our
+method uses only local unitaries and type-I fusion operations. The increased
+efficiency of our method compared to previously proposed constructions is
+obtained by identifying and exploiting local equivalence properties inherent in
+cluster states.",0512110v1
+2007-10-26,The dark matter as a light gravitino,"We address the question of gravitino dark matter in the context of gauge
+mediated supersymmetry breaking models. A special emphasis is put on the role
+played by the MSSM singlet messenger in the case of SO(10) grand unification.",0710.5121v1
+2008-03-05,Innovative Weak Formulation for The Landau-Lifshitz-Gilbert Equations,"A non-conventional finite element formalism is proposed to solve the dynamic
+Landau-Lifshitz-Gilbert micromagnetic equations. Two bidimensional test
+problems are treated to estimate the validity and the accuracy of this finite
+element approach",0803.0599v1
+2008-10-27,The profile of bubbling solutions of a class of fourth order geometric equations on 4-manifolds,"We study a class of fourth order geometric equations defined on a
+4-dimensional compact Riemannian manifold which includes the Q-curvature
+equation. We obtain sharp estimates on the difference near the blow-up points
+between a bubbling sequence of solutions and the standard bubble.",0810.4879v1
+2009-03-02,Asymptotic Improvement of the Binary Gilbert-Varshamov Bound on the Code Rate,"We compute the code parameters for binary linear codes obtained by greedy
+constructing the parity check matrix. Then we show that these codes improve the
+Gilbert-Varshamov (GV) bound on the code size and rate. This result counter
+proves the conjecture on the asymptotical exactness of the binary GV bound.",0903.0302v2
+2009-11-16,The Independent Chip Model and Risk Aversion,"We consider the Independent Chip Model (ICM) for expected value in poker
+tournaments. Our first result is that participating in a fair bet with one
+other player will always lower one's expected value under this model. Our
+second result is that the expected value for players not participating in a
+fair bet between two players always increases. We show that neither result
+necessarily holds for a fair bet among three or more players.",0911.3100v1
+2011-03-29,Statistical properties of $r$-adic processes and their connections to families of popular fractal curves,"Results concerning the statists of $r$-adic processes and their fractal
+properties are reviewed. The connection between singular eigenstates of the
+statistical evolution of such processes and popular fractal curves is
+emphasized.",1103.5683v1
+2011-05-09,Global Solvability of the Cauchy Problem for the Landau-Lifshitz-Gilbert Equation in Higher Dimensions,"We prove existence, uniqueness and asymptotics of global smooth solutions for
+the Landau-Lifshitz-Gilbert equation in dimension $n \ge 3$, valid under a
+smallness condition of initial gradients in the $L^n$ norm. The argument is
+based on the method of moving frames that produces a covariant complex
+Ginzburg-Landau equation, and a priori estimates that we obtain by the method
+of weighted-in-time norms as introduced by Fujita and Kato.",1105.1597v1
+2012-03-28,Fibonacci numbers in phyllotaxis : a simple model,"A simple model is presented which explains the occurrence of high order
+Fibonacci number parastichies in asteracae flowers by two distinct steps. First
+low order parastichies result from the fact that a new floret, at its
+appearance is repelled by two former ones, then, in order to accommodate for
+the increase of the radius, parastichies numbers have to evolve and can do it
+only by applying the Fibonacci recurrence formula.",1203.6257v1
+2014-02-19,Ordered groupoids and the holomorph of an inverse semigroup,"We present a construction for the holomorph of an inverse semigroup, derived
+from the cartesian closed structure of the category of ordered groupoids. We
+compare the holomorph with the monoid of mappings that preserve the ternary
+heap operation on an inverse semigroup: for groups these two constructions
+coincide. We present detailed calculations for semilattices of groups and for
+the polycyclic monoids.",1402.4592v1
+2014-11-01,Functorial Zeta Integrals,"The functional equation for nonarchimedean Rankin-Selberg local Euler factors
+was proved by Jacquet, Piatetski-Shapiro, and Shalika in 1983. In this
+expository note we translate the original proof into the purely functorial
+language of parabolic induction-restriction of Bernstein-Zelevinsky. This new
+language gives a clearer presentation of the ideas, and works over arbitrary
+fields with characteristic not equal to the residue characteristic.",1411.0148v1
+2016-02-17,Dispersion and Scaling Law of Dynamic Hysteresis Based on the Landau-Lifshitz-Gilbert Model,"Hysteresis dispersion under a varying external field Hex is investigated
+through numerical simulations based on the Landau-Lifshitz-Gilbert (LLG)
+equation, indicating the energy dissipation can be determined by W({\eta}) = A
+(f, H0). A linear relation between area of hysteresis and magnitude of external
+field is discovered. Evolution of hysteresis is also investigated under
+oscillating external field.",1602.05375v1
+2016-06-06,Proof of tightness of Varshamov - Gilbert bound for binary codes,"We prove tightness of right logarithmic asymptotic of Varshamov- Gilbert
+bound for linear binary codes We find general asymptotic coding bound for
+linear codes",1606.01592v5
+2017-02-21,Cohomology and extensions of ordered groupoids,"We adapt and generalise results of Loganathan on the cohomology of inverse
+semigroups to the cohomology of ordered groupoids. We then derive a five-term
+exact sequence in cohomology from an extension of ordered groupoids, and show
+that this sequence leads to a classification of extensions by a second
+cohomology group. Our methods use structural ideas in cohomology as far as
+possible, rather than computation with cocycles.",1702.06333v1
+2017-05-11,Two Gilbert-Varshamov Type Existential Bounds for Asymmetric Quantum Error-Correcting Codes,"In this note we report two versions of Gilbert-Varshamov type existential
+bounds for asymmetric quantum error-correcting codes.",1705.04087v2
+2017-09-21,Self-Dual Codes better than the Gilbert--Varshamov bound,"We show that every self-orthogonal code over $\mathbb F_q$ of length $n$ can
+be extended to a self-dual code, if there exists self-dual codes of length $n$.
+Using a family of Galois towers of algebraic function fields we show that over
+any nonprime field $\mathbb F_q$, with $q\geq 64$, except possibly $q=125$,
+there are self-dual codes better than the asymptotic Gilbert--Varshamov bound.",1709.07221v1
+2018-10-12,A convex approach to the Gilbert-Steiner problem,"We describe a convex relaxation for the Gilbert-Steiner problem both in $R^d$
+and on manifolds, extending the framework proposed in [9], and we discuss its
+sharpness by means of calibration type arguments. The minimization of the
+resulting problem is then tackled numerically and we present results for an
+extensive set of examples. In particular we are able to address the Steiner
+tree problem on surfaces.",1810.05417v1
+2018-11-09,Finslerian metrics locally conformally $R$-Einstein,"Let $R$ be the $hh$-curvature associated with the Chern connection or the
+Cartan connection. Adopting the pulled-back tangent bundle approach to the
+Finslerian Geometry, an intrinsic characterization of $R$-Einstein metrics is
+given. Finslerian metrics which are locally conformally $R$-Einstein are
+classified.",1811.04077v3
+2019-02-05,Harmonic maps with prescribed singularities and applications in general relativity,"This paper presents a general existence and uniqueness result for harmonic
+maps with prescribed singularities into non-positively curved targets, and
+surveys a number of applications to general relativity. It is based on a talk
+delivered by the author at The 11th Mathematical Society of Japan Seasonal
+Institute, The Role of Metrics in the Theory of Partial Differential Equations.",1902.01576v2
+2020-03-13,3D Stochastic Landau-Lifshitz-Gilbert Equations coupled with Maxwell's Equations with full energy,"We consider 3D stochastic Landau-Lifshitz-Gilbert equations coupled with the
+Maxwell equations with the full energy. We have proved the existence and some
+further regularities of the weak solution.",2003.06091v4
+2021-12-09,Induced Semi-Riemannian structures on null submanifolds,"In this paper, we induce a semi-Riemannian metric on the $r$-null
+submanifold. We establish the links between the null geometry and basics
+invariants of the associated semi-Riemannian geometry on $r$-null submanifold
+and semi-Riemannian constructed from a semi-Riemannian ambient.",2112.07348v1
+2022-04-12,How to design a network architecture using capacity planning,"Building a network architecture must answer to organization needs, but also
+to two major elements which are the need for dependability and performance. By
+performance, we must understand the ability to meet an immediate need and the
+ability to scale without reducing the performance of the whole as new elements
+are added to the network infrastructure. This last point is covered by Capacity
+Planning domain.",2204.05916v2
+2022-07-31,Moduli of Representations of Skewed-Gentle Algebras,"We prove irreducible components of moduli spaces of semistable
+representations of skewed-gentle algebras, and more generally, clannish
+algebras, are isomorphic to products of projective spaces. This is achieved by
+showing irreducible components of varieties of representations of clannish
+algebras can be viewed as irreducible components of skewed-gentle algebras,
+which we show are always normal. The main theorem generalizes an analogous
+result for moduli of representations of special biserial algebras proven by
+Carroll-Chindris-Kinser-Weyman.",2208.00336v1
+2022-08-01,iOCR: Informed Optical Character Recognition for Election Ballot Tallies,"The purpose of this study is to explore the performance of Informed OCR or
+iOCR. iOCR was developed with a spell correction algorithm to fix errors
+introduced by conventional OCR for vote tabulation. The results found that the
+iOCR system outperforms conventional OCR techniques.",2208.00865v1
+2023-03-13,Adaptive mesh refinement for the Landau-Lifshitz-Gilbert equation,"We propose a new adaptive algorithm for the approximation of the
+Landau-Lifshitz-Gilbert equation via a higher-order tangent plane scheme. We
+show that the adaptive approximation satisfies an energy inequality and
+demonstrate numerically, that the adaptive algorithm outperforms uniform
+approaches.",2303.07463v1
+2023-05-08,Evaluation of the Gilbert-Varshamov Bound using Multivariate Analytic Combinatorics,"Analytic combinatorics in several variables refers to a suite of tools that
+provide sharp asymptotic estimates for certain combinatorial quantities. In
+this paper, we apply these tools to determine the Gilbert-Varshamov (GV) bound
+for the sticky insertion and the constrained-synthesis channel.",2305.04439v1
+2023-12-11,Matrix Formulae and Skein Relations for Quasi-cluster Algebras,"In this paper, we give matrix formulae for non-orientable surfaces that
+provide the Laurent expansion for quasi-cluster variables, generalizing the
+orientable surface matrix formulae by Musiker-Williams. We additionally use our
+matrix formulas to prove the skein relations for the elements in the
+quasi-cluster algebra associated to curves on the non-orientable surface.",2312.06148v1
+2009-08-12,Linear Fractionally Damped Oscillator,"In this paper the linearly damped oscillator equation is considered with the
+damping term generalized to a Caputo fractional derivative. The order of the
+derivative being considered is 0 less than or equal to nu which is less than or
+equal to 1 . At the lower end, nu = 0, the equation represents an un-damped
+oscillator and at the upper end, nu = 1, the ordinary linearly damped
+oscillator equation is recovered. A solution is found analytically and a
+comparison with the ordinary linearly damped oscillator is made. It is found
+that there are nine distinct cases as opposed to the usual three for the
+ordinary equation (damped, over-damped, and critically damped). For three of
+these cases it is shown that the frequency of oscillation actually increases
+with increasing damping order before eventually falling to the limiting value
+given by the ordinary damped oscillator equation. For the other six cases the
+behavior is as expected, the frequency of oscillation decreases with increasing
+order of the derivative (damping term).",0908.1683v1
+1997-10-02,Dust and elemental abundances in Damped Ly alpha absorbers,"The effects of the dust on the determination of elemental abundances in
+damped Ly alpha (DLA) absorbers are investigated. Relations between the
+observed abundances measured in the gas phase and the overall abundances (gas
+plus dust) are derived as a function of dust-to-gas ratio, metallicity,
+element-to-element abundance pattern, average extinction coefficient of dust
+grains, and chemical composition of dust grains. A method is presented for
+determining dust-to-gas ratios, dust-to-metals ratios, and dust-corrected
+relative abundances in DLA absorbers by assuming dust of Galactic type and
+constant abundance ratios between iron-peak elements. The method is applied to
+a sample of 17 DLA absorbers with available Zn, Cr and/or Fe measurements. The
+resulting dust-to-gas ratios are mostly distributed between 2% and 25% of the
+Galactic value, in good quantitative agreement with the results from reddening
+studies of QSOs with foreground DLA absorption. A correlation is found between
+dust-to-gas ratio and metallicity in DLA galaxies, with a typical
+dust-to-metals ratio of ~ 60% the Galactic value. The derived dust-to-metals
+ratios are then used to correct from the effects of dust the abundance ratios
+[Si/Fe], [S/Fe], [Ti/Fe], [Mn/Fe], [Ni/Fe] available for a sub-sample of 9
+absorbers. The [alpha/Fe] ratios corrected from dust do not show the
+enhancement characteristic of metal-poor Galactic stars, but instead have
+essentially solar values, within +/- 0.2 dex. This suggests that the chemical
+history of DLA absorbers is different from that experienced by the Milky Way.
+Evidences that point to dwarf galaxies, rather than to spiral galaxies, as
+important contributors to the DLA phenomenon are summarized.",9710026v1
+2002-11-26,R-modes of neutron stars with the superfluid core,"We investigate the modal properties of the $r$-modes of rotating neutron
+stars with the core filled with neutron and proton superfluids, taking account
+of entrainment effects between the superfluids. The stability of the $r$-modes
+against gravitational radiation reaction is also examined considering viscous
+dissipation due to shear and a damping mechanism called mutual friction between
+the superfluids in the core. We find the $r$-modes in the superfluid core are
+split into ordinary $r$-modes and superfluid $r$-modes, which we call,
+respectively, $r^o$- and $r^s$-modes. The two superfluids in the core flow
+together for the $r^o$-modes, while they counter-move for the $r^s$-modes. For
+the $r^o$-modes, the coefficient $\kappa_0\equiv\lim_{\Omega\to
+0}\omega/\Omega$ is equal to $2m/[l^\prime(l^\prime+1)]$, almost independent of
+the parameter $\eta$ that parameterizes the entrainment effects between the
+superfluids, where $\Omega$ is the angular frequency of rotation, $\omega$ the
+oscillation frequency observed in the corotating frame of the star, and
+$l^\prime$ and $m$ are the indices of the spherical harmonic function
+representing the angular dependence of the $r$-modes. For the $r^s$-modes, on
+the other hand, $\kappa_0$ is equal to $2m/[l^\prime(l^\prime+1)]$ at $\eta=0$
+(no entrainment), and it almost linearly increases as $\eta$ is increased from
+$\eta=0$. The mutual friction in the superfluid core is found ineffective to
+stabilize the $r$-mode instability caused by the $r^o$-mode except in a few
+narrow regions of $\eta$. The $r$-mode instability caused by the $r^s$-modes,
+on the other hand, is extremely weak and easily damped by dissipative processes
+in the star.",0211580v1
+2006-02-06,Voigt Profile Fitting to Quasar Absorption Lines: An Analytic Approximation to the Voigt-Hjerting Function,"The Voigt-Hjerting function is fundamental in order to correctly model the
+profiles of absorption lines imprinted in the spectra of bright background
+sources by intervening absorbing systems. In this work we present a simple
+analytic approximation to this function in the context of absorption line
+profiles of intergalactic HI absorbers. Using basic calculus tools, we derive
+an analytic expression for the Voigt-Hjerting function that contains only
+fourth order polynomial and Gaussian functions. In connection with the
+absorption coefficient of intergalactic neutral hydrogen, this approximation is
+suitable for modeling Voigt profiles with an accuracy of $10^{-4}$ or better
+for an arbitrary wavelength baseline, for column densities up to $N_{HI} =
+10^{22} cm^{-2}$, and for damping parameters $a \lesssim 10^{-4}$, i.e. the
+entire range of parameters characteristic to all Lyman transitions arising in a
+variety of HI absorbing systems such as Lyman Alpha Forest clouds, Lyman Limit
+systems and Damped Lyman Alpha systems. We hence present an approximation to
+the Voigt-Hjerting function that is both accurate and flexible to implement in
+various types of programming languages and machines, and with which Voigt
+profiles can be calculated in a reliable and very simple manner.",0602124v2
+2003-10-29,Superparamagnetism and Spin Glass Dynamics of Interacting Magnetic Nanoparticle Systems,"The physical properties of magnetic nanoparticles have been investigated with
+focus on the influence of dipolar interparticle interaction. For weakly coupled
+nanoparticles, thermodynamic perturbation theory is employed to derive
+analytical expressions for the linear equilibrium susceptibility, the
+zero-field specific heat and averages of the local dipolar fields. By
+introducing the averages of the dipolar fields in an expression for the
+relaxation rate of a single particle, a nontrivial dependence of the
+superparamagnetic blocking on the damping coefficient is evidenced. This
+damping dependence is interpreted in terms of the nonaxially symmetric
+potential created by the transverse component of the dipolar field.
+  Strongly interacting nanoparticle systems are investigated experimentally in
+terms of spin glass behavior. Disorder and frustration arise in samples
+consisting of frozen ferrofluids from the randomness in particle position and
+anisotropy axis orientation. A strongly interacting FeC system is shown to
+exhibit critical dynamics characteristic of a spin glass phase transition.
+Aging, memory and rejuvenation phenomena similar to those of conventional spin
+glasses are observed, albeit with much weaker rejuvenation effects than in both
+a Ag(11 at% Mn) Heisenberg and an Fe_{0.5}Mn_{0.5}TiO_3 Ising spin glass.
+Differences in the nonequilibrium dynamics of the strongly interacting
+nanoparticle system and the two spin glass samples are discussed in terms of
+anisotropy and different timescales, due to the much longer microscopic flip
+time of a magnetic moment than of an atomic spin.",0310684v2
+1996-12-31,Fluid Models for Kinetic Effects on Coherent Nonlinear Alfven Waves. I. Fundamental Theory,"Collisionless regime kinetic models for coherent nonlinear Alfven wave
+dynamics are studied using fluid moment equations with an approximate closure
+anzatz. Resonant particle effects are modelled by incorporating an additional
+term representing dissipation akin to parallel heat conduction. Unlike
+collisional dissipation, parallel heat conduction is presented by an integral
+operator. The modified derivative nonlinear Schrodinger equation thus has a
+spatially nonlocal nonlinear term describing the long-time evolution of the
+envelope of parallel-propagating Alfven waves, as well. Coefficients in the
+nonlinear terms are free of the 1/(1-beta) singularity usually encountered in
+previous analyses, and have very a simple form which clarifies the physical
+processes governing the large amplitude Alfvenic nonlinear dynamics. The
+nonlinearity appears via coupling of an Alfvenic mode to a kinetic ion-acoustic
+mode. Damping of the nonlinear Alfven wave appears via strong Landau damping of
+the ion-acoustic wave when the electron-to-ion temperature ratio is close to
+unity. For a (slightly) obliquely propagating wave, there are finite Larmor
+radius corrections in the dynamical equation. This effect depends on the angle
+of wave propagation relative to B_0 and vanishes for the limit of strictly
+parallel propagation. Explicit magnetic perturbation envelope equations
+amenable to further analysis and numerical solution are obtained. Implications
+of these models for collisionless shock dynamics are discussed.",9612017v1
+2008-06-01,Ray-based calculations of backscatter in laser fusion targets,"A 1D, steady-state model for Brillouin and Raman backscatter from an
+inhomogeneous plasma is presented. The daughter plasma waves are treated in the
+strong damping limit, and have amplitudes given by the (linear) kinetic
+response to the ponderomotive drive. Pump depletion, inverse-bremsstrahlung
+damping, bremsstrahlung emission, Thomson scattering off density fluctuations,
+and whole-beam focusing are included. The numerical code DEPLETE, which
+implements this model, is described. The model is compared with traditional
+linear gain calculations, as well as ""plane-wave"" simulations with the paraxial
+propagation code pF3D. Comparisons with Brillouin-scattering experiments at the
+OMEGA Laser Facility [T. R. Boehly et al., Opt. Commun. 133, p. 495 (1997)]
+show that laser speckles greatly enhance the reflectivity over the DEPLETE
+results. An approximate upper bound on this enhancement, motivated by phase
+conjugation, is given by doubling the DEPLETE coupling coefficient. Analysis
+with DEPLETE of an ignition design for the National Ignition Facility (NIF) [J.
+A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Technol. 26, p. 755
+(1994)], with a peak radiation temperature of 285 eV, shows encouragingly low
+reflectivity. Re-absorption of Raman light is seen to be significant in this
+design.",0806.0045v2
+2015-07-06,Fast inertial dynamics and FISTA algorithms in convex optimization. Perturbation aspects,"In a Hilbert space setting $\mathcal H$, we study the fast convergence
+properties as $t \to + \infty$ of the trajectories of the second-order
+differential equation $ \ddot{x}(t) + \frac{\alpha}{t} \dot{x}(t) + \nabla \Phi
+(x(t)) = g(t)$, where $\nabla\Phi$ is the gradient of a convex continuously
+differentiable function $\Phi: \mathcal H \to \mathbb R$, $\alpha$ is a
+positive parameter, and $g: [t_0, + \infty[ \rightarrow \mathcal H$ is a
+""small"" perturbation term. In this damped inertial system, the viscous damping
+coefficient $\frac{\alpha}{t}$ vanishes asymptotically, but not too rapidly.
+  For $\alpha \geq 3$, and $\int_{t_0}^{+\infty} t \|g(t)\| dt < + \infty$,
+just assuming that the solution set is non empty, we show that any trajectory
+of the above system satisfies the fast convergence property $\Phi(x(t))-
+\min_{\mathcal H}\Phi \leq \frac{C}{t^2}$. For $\alpha > 3$, we show that any
+trajectory converges weakly to a minimizer of $\Phi$, and we show the strong
+convergence property in various practical situations. This complements the
+results obtained by Su-Boyd- Cand\`es, and Attouch-Peypouquet-Redont, in the
+unperturbed case $g=0$. The parallel study of the time discretized version of
+this system provides new insight on the effect of errors, or perturbations on
+Nesterov's type algorithms. We obtain fast convergence of the values, and
+convergence of the trajectories for a perturbed version of the variant of FISTA
+recently considered by Chambolle-Dossal, and Su-Boyd-Cand\`es.",1507.01367v1
+2016-02-05,Combining fast inertial dynamics for convex optimization with Tikhonov regularization,"In a Hilbert space setting $\mathcal H$, we study the convergence properties
+as $t \to + \infty$ of the trajectories of the second-order differential
+equation \begin{equation*}
+  \mbox{(AVD)}_{\alpha, \epsilon} \quad \quad \ddot{x}(t) + \frac{\alpha}{t}
+\dot{x}(t) + \nabla \Phi (x(t)) + \epsilon (t) x(t) =0, \end{equation*} where
+$\nabla\Phi$ is the gradient of a convex continuously differentiable function
+$\Phi: \mathcal H \to \mathbb R$, $\alpha$ is a positive parameter, and
+$\epsilon (t) x(t)$ is a Tikhonov regularization term, with $\lim_{t \to
+\infty}\epsilon (t) =0$. In this damped inertial system, the damping
+coefficient $\frac{\alpha}{t}$ vanishes asymptotically, but not too quickly, a
+key property to obtain rapid convergence of the values. In the case $\epsilon
+(\cdot) \equiv 0$, this dynamic has been highlighted recently by Su, Boyd, and
+Cand\`es as a continuous version of the Nesterov accelerated method. Depending
+on the speed of convergence of $\epsilon (t)$ to zero, we analyze the
+convergence properties of the trajectories of $\mbox{(AVD)}_{\alpha,
+\epsilon}$. We obtain results ranging from the rapid convergence of $\Phi
+(x(t))$ to $\min \Phi$ when $\epsilon (t)$ decreases rapidly to zero, up to the
+strong ergodic convergence of the trajectories to the element of minimal norm
+of the set of minimizers of $\Phi$, when $\epsilon (t)$ tends slowly to zero.",1602.01973v1
+2016-02-19,Resonant absorption and amplification of circularly-polarized waves in inhomogeneous chiral media,"It has been found that in the media where the dielectric permittivity
+$\epsilon$ or the magnetic permeability $\mu$ is near zero and in transition
+metamaterials where $\epsilon$ or $\mu$ changes from positive to negative
+values, there occur a strong absorption or amplification of the electromagnetic
+wave energy in the presence of an infinitesimally small damping or gain and a
+strong enhancement of the electromagnetic fields. We attribute these phenomena
+to the mode conversion of transverse electromagnetic waves into longitudinal
+plasma oscillations and its inverse process. In this paper, we study analogous
+phenomena occurring in chiral media theoretically using the invariant imbedding
+method. In uniform isotropic chiral media, right-circularly-polarized and
+left-circularly-polarized waves are the eigenmodes of propagation with
+different effective refractive indices $n_+$ and $n_-$, whereas in the chiral
+media with a nonuniform impedance variation, they are no longer the eigenmodes
+and are coupled to each other. We find that both in uniform chiral slabs where
+either $n_+$ or $n_-$ is near zero and in chiral transition metamaterials where
+$n_+$ or $n_-$ changes from positive to negative values, a strong absorption or
+amplification of circularly-polarized waves occurs in the presence of an
+infinitesimally small damping or gain. We present detailed calculations of the
+mode conversion coefficient, which measures the fraction of the electromagnetic
+wave energy absorbed into the medium, for various configurations of $\epsilon$
+and $\mu$ with an emphasis on the influence of a nonuniform impedance. We
+propose possible applications of these phenomena to linear and nonlinear
+optical devices that react selectively to the helicity of the circular
+polarization.",1602.06022v1
+2018-06-22,Overcoming obstacles in nonequilibrium holography,"We study universal spatial features of certain non-equilibrium steady states
+corresponding to flows of strongly correlated fluids over obstacles. This
+allows us to predict universal spatial features of far-from-equilibrium
+systems, which in certain interesting cases depend cleanly on the hydrodynamic
+transport coefficients of the underlying theory, such as $\eta/s$, the shear
+viscosity to entropy density ratio. In this work we give a purely
+field-theoretical definition of the spatial collective modes identified earlier
+and proceed to demonstrate their usefulness in a set of examples, drawing on
+hydrodynamic theory as well as holographic duality. We extend our earlier
+treatment by adding a finite chemical potential, which introduces a
+qualitatively new feature, namely damped oscillatory behavior in space. We find
+interesting transitions between oscillatory and damped regimes and we consider
+critical exponents associated with these. We explain in detail the numerical
+method and add a host of new examples, including fully analytical ones. Such a
+treatment is possible in the large-dimension limit of the bulk theory, as well
+as in three dimensions, where we also exhibit a fully analytic non-linear
+example that beautifully illustrates the original proposal of spatial
+universality. This allows us to explicitly demonstrate how an infinite tower of
+discrete modes condenses into a branch cut in the zero-temperature limit,
+converting exponential decay into a power law tail.",1806.08655v1
+2018-06-28,Optimizing wave-generation and wave-damping in 3D-flow simulations with implicit relaxation-zones,"In finite-volume-based flow-simulations with free-surface waves, wave
+reflections at the domain boundaries can cause substantial errors in the
+results and must therefore be minimized. This can be achieved via `implicit
+relaxation zones', but only if the relaxation zone's case-dependent parameters
+are optimized. This work proposes an analytical approach for optimizing these
+parameters. The analytical predictions are compared against results from
+2D-flow simulations for different water depths, flow solvers, and relaxation
+functions, and against results from 3D-flow simulations with strongly
+wave-reflecting bodies subjected to nonlinear free-surface waves. The present
+results demonstrate that the proposed approach satisfactorily predicts both the
+optimum parameter settings and the upper-limit for the corresponding reflection
+coefficients $C_{\mathrm{R}}$. Simulation results for $C_{\mathrm{R}}$ were
+mostly below or equal to the analytical predictions, but never more than
+$3.4\%$ larger. Therefore, the proposed approach can be recommended for
+engineering practice. Furthermore, it is shown that implicit relaxation zones
+can be considered as a special-case of forcing zones, a family of approaches
+which includes among others absorbing layers, damping zones and sponge layers.
+The commonalities and differences between these approaches are discussed,
+including to what extend the present findings are applicable to these other
+approaches and vice versa.",1806.10995v3
+2018-07-06,On the use of circulant matrices for the stability analysis of recent weakly compressible SPH methods,"In this study, a linear stability analysis is performed for different Weakly
+Compressible Smooth Particle Hydrodynamics (WCSPH) methods on a 1D periodic
+domain describing an incompressible base flow. The perturbation equation can be
+vectorized and written as an ordinary differential equation where the
+coefficients are circulant matrices. The diagonalization of the system is
+equivalent to apply a spatial discrete Fourier transform. This leads to
+stability conditions expressed by the discrete Fourier transform of the first
+and second derivatives of the kernel. Although spurious modes are highlighted,
+no tensile nor pairing instabilities are found in the present study, suggesting
+that the perturbations of the stresses are always damped if the base flow is
+incompressible. The perturbations equation is solved in the Laplace domain,
+allowing to derive an analytical solution of the transient state. Also, it is
+demonstrated analytically that a positive background pressure combined with the
+uncorrected gradient operator leads to a reordering of the particle lattice. It
+is also shown that above a critical value, the background pressure leads to
+instabilities. Finally, the dispersion curves for inviscid and viscous flows
+are plotted for different WCSPH methods and compared to the continuum solution.
+It is observed that a background pressure equal to $\rho c^2$ gives the best
+fidelity to predict the propagation of a sound wave. When viscosity effects are
+taken into account, the damping of pressure fluctuations show the best
+agreement with the continuum for $p_{back} \sim \rho c^2/2$.",1807.02315v2
+2018-08-15,Pull-in dynamics of overdamped microbeams,"We study the dynamics of MEMS microbeams undergoing electrostatic pull-in. At
+DC voltages close to the pull-in voltage, experiments and numerical simulations
+have reported `bottleneck' behaviour in which the transient dynamics slow down
+considerably. This slowing down is highly sensitive to external forces, and so
+has widespread potential for applications that use pull-in time as a sensing
+mechanism, including high-resolution accelerometers and pressure sensors.
+Previously, the bottleneck phenomenon has only been understood using lumped
+mass-spring models that do not account for effects such as variable residual
+stress and different boundary conditions. We extend these studies to
+incorporate the beam geometry, developing an asymptotic method to analyse the
+pull-in dynamics. We attribute bottleneck behaviour to critical slowing down
+near the pull-in transition, and we obtain a simple expression for the pull-in
+time in terms of the beam parameters and external damping coefficient. This
+expression is found to agree well with previous experiments and numerical
+simulations that incorporate more realistic models of squeeze film damping, and
+so provides a useful design rule for sensing applications. We also consider the
+accuracy of a single-mode approximation of the microbeam equations --- an
+approach that is commonly used to make analytical progress, without systematic
+investigation of its accuracy. By comparing to our bottleneck analysis, we
+identify the factors that control the error of this approach, and we
+demonstrate that this error can indeed be very small.",1808.05237v1
+2019-07-05,"Response solutions to quasi-periodically forced systems, even to possibly ill-posed PDEs, with strong dissipation and any frequency vectors","We consider several models (including both multidimensional ordinary
+differential equations (ODEs) and partial differential equations (PDEs),
+possibly ill-posed), subject to very strong damping and quasi-periodic external
+forcing. We study the existence of response solutions (i.e., quasi-periodic
+solutions with the same frequency as the forcing). Under some regularity
+assumptions on the nonlinearity and forcing, without any arithmetic condition
+on the forcing frequency $\omega$, we show that the response solutions indeed
+exist. Moreover, the solutions we obtained possess optimal regularity in
+$\varepsilon$ (where $\varepsilon$ is the inverse of the coefficients
+multiplying the damping) when we consider $\varepsilon$ in a domain that does
+not include the origin $\varepsilon=0$ but has the origin on its boundary. We
+get that the response solutions depend continuously on $\varepsilon$ when we
+consider $\varepsilon $ tends to $0$. However, in general, they may not be
+differentiable at $\varepsilon=0$. In this paper, we allow multidimensional
+systems and we do not require that the unperturbed equations under
+consideration are Hamiltonian. One advantage of the method in the present paper
+is that it gives results for analytic, finitely differentiable and low
+regularity forcing and nonlinearity, respectively. As a matter of fact, we do
+not even need that the forcing is continuous. Notably, we obtain results when
+the forcing is in $L^2$ space and the nonlinearity is just Lipschitz as well as
+in the case that the forcing is in $H^1$ space and the nonlinearity is $C^{1 +
+\text{Lip}}$. In the proof of our results, we reformulate the existence of
+response solutions as a fixed point problem in appropriate spaces of smooth
+functions.",1907.02835v1
+2020-06-23,Unexpected convergence of lattice Boltzmann schemes,"In this work, we study numerically the convergence of the scalar D2Q9 lattice
+Boltzmann scheme with multiple relaxation times when the time step is
+proportional to the space step and tends to zero. We do this by a combination
+of theory and numerical experiment. The classical formal analysis when all the
+relaxation parameters are fixed and the time step tends to zero shows that the
+numerical solution converges to solutions of the heat equation, with a
+constraint connecting the diffusivity, the space step and the coefficient of
+relaxation of the momentum. If the diffusivity is fixed and the space step
+tends to zero, the relaxation parameter for the momentum is very small, causing
+a discrepency between the previous analysis and the numerical results. We
+propose a new analysis of the method for this specific situation of evanescent
+relaxation, based on the dispersion equation of the lattice Boltzmann scheme. A
+new asymptotic partial differential equation, the damped acoustic system, is
+emergent as a result of this formal analysis. Complementary numerical
+experiments establish the convergence of the scalar D2Q9 lattice Boltzmann
+scheme with multiple relaxation times and acoustic scaling in this specific
+case of evanescent relaxation towards the numerical solution of the damped
+acoustic system.",2006.12947v1
+2020-09-13,Inertia and feedback parameters adaptive control of virtual synchronous generator,"The virtual synchronous generator technology analogs the characteristics of
+the synchronous generator via the controller design. It improved the stability
+of the grid systems which include the new energy. At the same time, according
+to the adjustable characteristics of the virtual synchronous generator
+parameters, the parameter adaptive adjustment is used to improve the dynamic
+performance of the system. However, the traditional virtual synchronous
+generator adaptive control technology still has two drawbacks: on the one hand,
+the large-scale adjustment of the damping droop coefficient and the virtual
+moment of inertia requires the system having a high energy storage margin; On
+the other hand, there is a power overshoot phenomenon in the transient
+regulation process, which is disadvantageous to the power equipment. First,
+this paper provides a convenient adjustment method for improving the transient
+stability of the system, the system damping is adjusted by introducing the
+output speed feedback. Second, according to the transient power-angle
+characteristics of the system, a parameter adaptive control strategy is
+proposed, which shortens the transient adjustment time and ensures that the
+deviation of the system frequency in the transient adjustment process is within
+the allowable range, and improves the transient performance of the grid
+frequency adjustment, at the same time, the power overshoot is suppressed.
+Finally, the experimental results show that the proposed control strategy is
+superior to the existing adaptive control strategy.",2009.05916v1
+2021-02-03,Jerky active matter: a phase field crystal model with translational and orientational memory,"Most field theories for active matter neglect effects of memory and inertia.
+However, recent experiments have found inertial delay to be important for the
+motion of self-propelled particles. A major challenge in the theoretical
+description of these effects, which makes the application of standard methods
+very difficult, is the fact that orientable particles have both translational
+and orientational degrees of freedom which do not necessarily relax on the same
+time scale. In this work, we derive the general mathematical form of a field
+theory for soft matter systems with two different time scales. This allows to
+obtain a phase field crystal model for polar (i.e., nonspherical or active)
+particles with translational and orientational memory. Notably, this theory is
+of third order in temporal derivatives and can thus be seen as a spatiotemporal
+jerky dynamics. We obtain the phase diagram of this model, which shows that,
+unlike in the passive case, the linear stability of the liquid state depends on
+the damping coefficients. Moreover, we investigate sound waves in active
+matter. It is found that, in active fluids, there are two different mechanisms
+for sound propagation. For certain parameter values and sufficiently high
+frequencies, sound mediated by polarization waves experiences less damping than
+usual passive sound mediated by pressure waves of the same frequency. By
+combining the different modes, acoustic frequency filters based on active
+fluids could be realized.",2102.02169v1
+2021-04-23,Development of Advanced Linearized Gyrokinetic Collision Operators Using a Moment Approach,"The derivation and numerical implementation of a linearized version of the
+gyrokinetic (GK) Coulomb collision operator (Jorge R. et al., J. Plasma Phys.
+85, 905850604 (2019)) and of the widely-used linearized GK Sugama collision
+operator (Sugama H. et al., Phys. Plasmas 16, 112503 (2009)) is reported. An
+approach based on a Hermite-Laguerre moment expansion of the perturbed
+gyrocenter distribution function is used, referred to as gyro-moment expansion.
+This approach allows considering arbitrary perpendicular wavenumber and
+expressing the two linearized GK operators as a linear combination of
+gyro-moments where the expansion coefficients are given by closed analytical
+expressions that depend on the perpendicular wavenumber and on the temperature
+and mass ratios of the colliding species. The drift-kinetic (DK) limits of the
+GK linearized Coulomb and Sugama operators are also obtained. Comparisons
+between the gyro-moment approach with the GK continuum code GENE are reported
+focusing on the ion-temperature-gradient (ITG) instability and zonal flow (ZF)
+damping, finding an excellent agreement. In particular, we demonstrate that the
+GK linearized Sugama yields a stronger collisional damping of the ZF residual
+compared to the GK linearized Coulomb. Finally, we show that the numerical
+efficiency of the gyro-moment approach increases with collisionality, a desired
+property for boundary plasma applications.",2104.11480v2
+2021-05-19,Viscoelasticity and elastocapillarity effects in the impact of drops on a repellent surface,"We investigate freely expanding viscoelastic sheets. The sheets are produced
+by the impact of drops on a quartz plate covered with a thin layer of liquid
+nitrogen that suppresses shear viscous dissipation as a result of the cold
+Leidenfrost effect. The time evolution of the sheet is simultaneously recorded
+from top and side views using high-speed cameras. The investigated viscoelastic
+fluids are Maxwell fluids, which are characterized by low elastic moduli, and
+relaxation times that vary over almost two orders of magnitude, thus giving
+access to a large spectrum of viscoelastic and elastocapillary effects. For the
+purposes of comparison, Newtonian fluids, with viscosity varying over three
+orders of magnitude, are also investigated. In this study, $d_{\mathrm{max}}$,
+the maximal expansion of the sheets, and $t_{\mathrm{max}}$ the time to reach
+this maximal expansion from the time at impact, are measured as a function of
+the impact velocity. By using a generalized damped harmonic oscillator model,
+we rationalize the role of capillarity, bulk elasticity and viscous dissipation
+in the expansion dynamics of all investigated samples. In the model, the spring
+constant is a combination of the surface tension and the bulk dynamic elastic
+modulus. The time-varying damping coefficient is associated to biaxial
+extensional viscous dissipation and is proportional to the dynamic loss
+modulus. For all samples, we find that the model reproduces accurately the
+experimental data for $d_{\mathrm{max}}$ and $t_{\mathrm{max}}$.",2105.09244v1
+2021-12-29,Towards First-principle Characterization of Cosmic-ray Transport Coefficients from Multi-scale Kinetic Simulations,"A major uncertainty in understanding the transport and feedback of
+cosmic-rays (CRs) within and beyond our Galaxy lies in the unknown CR
+scattering rates, which are primarily determined by wave-particle interaction
+at microscopic gyro-resonant scales. The source of the waves for the bulk CR
+population is believed to be self-driven by the CR streaming instability
+(CRSI), resulting from the streaming of CRs downward a CR pressure gradient.
+While a balance between driving by the CRSI and wave damping is expected to
+determine wave amplitudes and hence the CR scattering rates, the problem
+involves significant scale separation with substantial ambiguities based on
+quasi-linear theory (QLT). Here we propose a novel ""streaming box"" framework to
+study the CRSI with an imposed CR pressure gradient, enabling first-principle
+measurement of the CR scattering rates as a function of environmental
+parameters. By employing the magnetohydrodynamic-particle-in-cell (MHD-PIC)
+method with ion-neutral damping, we conduct a series of simulations with
+different resolutions and CR pressure gradients and precisely measure the
+resulting CR scattering rates in steady state. The measured rates show scalings
+consistent with QLT, but with a normalization smaller by a factor of several
+than typical estimates based on single-fluid treatment of CRs. A
+momentum-by-momentum treatment provides better estimates when integrated over
+momentum, but is also subject substantial deviations especially at small
+momentum. Our framework thus opens up the path towards providing comprehensive
+subgrid physics for macroscopic studies of CR transport and feedback in broad
+astrophysical contexts.",2112.14782v2
+2022-01-17,Sizing of Energy Storage System for Virtual Inertia Emulation,"The infusion of renewable energy sources into the conventional synchronous
+generation system decreases the overall system inertia and negatively impacts
+the stability of its primary frequency response. The lowered inertia is due to
+the absence of inertia in some of the renewable energy-based systems. To
+maintain the stability of the system, we need to keep the frequency in the
+permissible limits and maintain low rotational inertia. Some authors in the
+literature have used the virtual synchronous generators (VSG) as a solution to
+this problem. Although the VSG based distributed recourses (DER) exhibits the
+characteristics and behavior of synchronous generators (SG) such as inertia,
+frequency droop functions and damping but it does not optimally solve the
+question of frequency stability. This paper presents a solution for these
+problems via an empirical model that sizes the Battery Energy Storage System
+(BESS) required for the inertia emulation and damping control. The tested
+system consists of a Photovoltaic (PV) based VSG that is connected to a 9-Bus
+grid and the simulation experiments are carried out using EMTP software. The
+VSG transient response is initiated by a symmetric fault on the grid side. Our
+simulations show the battery energy sizing required to emulate the virtual
+inertia corresponding to several design parameters, i.e., the droop gain,
+K{\omega}, the droop coefficient, Kd, and the VSG time constant Ta.",2201.06566v2
+2022-04-12,The drag exerted by weakly dissipative trapped lee waves on the atmosphere: application to Scorer's two-layer model,"While it is known that trapped lee waves propagating at low levels in a
+stratified atmosphere exert a drag on the mountains that generate them, the
+distribution of the corresponding reaction force exerted on the atmospheric
+mean circulation, defined by the wave momentum flux profiles, has not been
+established, because for inviscid trapped lee waves these profiles oscillate
+indefinitely downstream. A framework is developed here for the unambiguous
+calculation of momentum flux profiles produced by trapped lee waves, which
+circumvents the difficulties plaguing the inviscid trapped lee wave theory.
+Using linear theory, and taking Scorer's two-layer atmosphere as an example,
+the waves are assumed to be subject to a small dissipation, expressed as a
+Rayleigh damping. The resulting wave pattern decays downstream, so the momentum
+flux profile integrated over the area occupied by the waves converges to a
+well-defined form. Remarkably, for weak dissipation, this form is independent
+of the value of Rayleigh damping coefficient, and the inviscid drag, determined
+in previous studies, is recovered as the momentum flux at the surface. The
+divergence of this momentum flux profile accounts for the areally-integrated
+drag exerted by the waves on the atmosphere. The application of this framework
+to this and other types of trapped lee waves potentially enables the
+development of physically-based parametrizations of the effects of trapped lee
+waves on the atmosphere.",2204.05858v1
+2022-08-30,Hyperon bulk viscosity and $r$-modes of neutron stars,"We propose and apply a new parameterization of the modified chiral effective
+model to study rotating neutron stars with hyperon cores in the framework of
+the relativistic mean-field theory. The inclusion of mesonic cross couplings in
+the model has improved the density content of the symmetry energy slope
+parameters, which are in agreement with the findings from recent terrestrial
+experiments. The bulk viscosity of the hyperonic medium is analyzed to
+investigate its role in the suppression of gravitationally driven $r$-modes.
+The hyperonic bulk viscosity coefficient caused by non-leptonic weak
+interactions and the corresponding damping timescales are calculated and the
+$r$-mode instability windows are obtained. The present model predicts a
+significant reduction of the unstable region due to a more effective damping of
+oscillations. We find that from $\sim 10^8$ K to $\sim 10^{9}$ K, hyperonic
+bulk viscosity completely suppresses the $r$-modes leading to a stable region
+between the instability windows. Our analysis indicates that the instability
+can reduce the angular velocity of the star up to $\sim$0.3~$\Omega_K$, where
+$\Omega_K$ is the Kepler frequency of the star.",2208.14436v1
+2023-02-19,Non-separable Covariance Kernels for Spatiotemporal Gaussian Processes based on a Hybrid Spectral Method and the Harmonic Oscillator,"Gaussian processes provide a flexible, non-parametric framework for the
+approximation of functions in high-dimensional spaces. The covariance kernel is
+the main engine of Gaussian processes, incorporating correlations that underpin
+the predictive distribution. For applications with spatiotemporal datasets,
+suitable kernels should model joint spatial and temporal dependence. Separable
+space-time covariance kernels offer simplicity and computational efficiency.
+However, non-separable kernels include space-time interactions that better
+capture observed correlations. Most non-separable kernels that admit explicit
+expressions are based on mathematical considerations (admissibility conditions)
+rather than first-principles derivations. We present a hybrid spectral approach
+for generating covariance kernels which is based on physical arguments. We use
+this approach to derive a new class of physically motivated, non-separable
+covariance kernels which have their roots in the stochastic, linear, damped,
+harmonic oscillator (LDHO). The new kernels incorporate functions with both
+monotonic and oscillatory decay of space-time correlations. The LDHO covariance
+kernels involve space-time interactions which are introduced by dispersion
+relations that modulate the oscillator coefficients. We derive explicit
+relations for the spatiotemporal covariance kernels in the three oscillator
+regimes (underdamping, critical damping, overdamping) and investigate their
+properties. We further illustrate the hybrid spectral method by deriving
+covariance kernels that are based on the Ornstein-Uhlenbeck model.",2302.09580v3
+2023-11-28,Energy diffusion in weakly interacting chains with fermionic dissipation-assisted operator evolution,"Interacting lattice Hamiltonians at high temperature generically give rise to
+energy transport governed by the classical diffusion equation; however,
+predicting the rate of diffusion requires numerical simulation of the
+microscopic quantum dynamics. For the purpose of predicting such transport
+properties, computational time evolution methods must be paired with schemes to
+control the growth of entanglement to tractably simulate for sufficiently long
+times. One such truncation scheme -- dissipation-assisted operator evolution
+(DAOE) -- controls entanglement by damping out components of operators with
+large Pauli weight. In this paper, we generalize DAOE to treat fermionic
+systems. Our method instead damps out components of operators with large
+fermionic weight. We investigate the performance of DAOE, the new fermionic
+DAOE (FDAOE), and another simulation method, density matrix truncation (DMT),
+in simulating energy transport in an interacting one-dimensional Majorana
+chain. The chain is found to have a diffusion coefficient scaling like
+interaction strength to the fourth power, contrary to naive expectations based
+on Fermi's Golden rule -- but consistent with recent predictions based on the
+theory of \emph{weak integrability breaking}. In the weak interaction regime
+where the fermionic nature of the system is most relevant, FDAOE is found to
+simulate the system more efficiently than DAOE.",2311.17148v2
+2005-03-08,Electron-Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. IX. Ni XXVI and Ni XXVII for UV and X-ray modeling,"The inverse processes of photoionization and electron-ion recombination of
+(hnu + Ni XXVI --> Ni XXVII + e and (hnu + Ni XXVII --> Ni XXVIII + e) are
+studied using the unified method for the total recombination. The method
+subsumes both the radiative and di-electronic recombination processes and
+enables self-consistent sets of results for photoionization and electron-ion
+recombination by using the same wavefunction expansion. Photoionization cross
+sections (sigma_PI), recombination cross sections (sigma_{RC}), recombination
+collision strengths (Omega_{RC}), and recombination rate coefficients
+(alpha_{RC}) are obtained for ionization balance and spectral analysis of UV
+and X-ray lines. Level-specific photoionization cross sections and
+recombination rates are presented to enable accurate computation of
+recombination-cascade matrices for all fine structure levels n(SLJ) up to n <=
+10: 98 bound fine structure levels of Ni XXVI with 0 <= l <= 9, 0 <= L <= 11,
+1/2 <= J <= 17/2, and 198 levels of Ni XXVII with 0 <= l <= 9, 0 <= L <= 14, 0
+<= J <= 10. Total alpha_{RC} for Ni XXVI and Ni XXVII are compared with the
+existing values with very good agreement. Total recombination rate coefficients
+for the hydrogen-like recombined ion, Ni XXVIII, are also presented. The
+calculations are carried out in relativistic Breit-Pauli R-matrix (BPRM)
+approximation with inclusion of radiation damping of resonances. With
+consideration of all details of the processes, the results, which include the
+level specific sigma_{PI} and alpha_{R} calculated for the first time, should
+be the most accurate for these ions.",0503197v1
+2013-09-12,Diffusive transport in Weyl semimetals,"Diffusion, a ubiquitous phenomenon in nature, is a consequence of particle
+number conservation and locality, in systems with sufficient damping. In this
+paper we consider diffusive processes in the bulk of Weyl semimetals, which are
+exotic quantum materials, recently of considerable interest. In order to do
+this, we first explicitly implement the analytical scheme by which disorder
+with anisotropic scattering amplitude is incorporated into the diagrammatic
+response-function formalism for calculating the `diffuson'. The result thus
+obtained is consistent with transport coefficients evaluated from the Boltzmann
+transport equation or the renormalized uniform current vertex calculation, as
+it should be. We thus demonstrate that the computation of the diffusion
+coefficient should involve the transport lifetime, and not the quasiparticle
+lifetime. Using this method, we then calculate the density response function in
+Weyl semimetals and discover an unconventional diffusion process that is
+significantly slower than conventional diffusion. This gives rise to relaxation
+processes that exhibit stretched exponential decay, instead of the usual
+exponential diffusive relaxation. This result is then explained using a model
+of thermally excited quasiparticles diffusing with diffusion coefficients which
+are strongly dependent on their energies. We elucidate the roles of the various
+energy and time scales involved in this novel process and propose an experiment
+by which this process may be observed.",1309.3278v1
+2018-01-03,Gravitational Waves in Locally Rotationally Symmetric (LRS) Class II Cosmologies,"In this work we consider perturbations of homogeneous and hypersurface
+orthogonal cosmological backgrounds with local rotational symmetry (LRS), using
+a method based on the 1 + 1 + 2 covariant split of spacetime. The backgrounds,
+of LRS class II, are characterised by that the vorticity, the twist of the
+2-sheets, and the magnetic part of the Weyl tensor all vanish. They include the
+flat Friedmann universe as a special case. The matter contents of the perturbed
+spacetimes are given by vorticity-free perfect fluids, but otherwise the
+perturbations are arbitrary and describe gravitational, shear, and density
+waves. All the perturbation variables can be given in terms of the time
+evolution of a set of six harmonic coefficients. This set decouples into one
+set of four coefficients with the density perturbations acting as source terms,
+and another set of two coefficients describing damped source-free gravitational
+waves with odd parity. We also consider the flat Friedmann universe, which~has
+been considered by several others using the 1 + 3 covariant split, as a check
+of the isotropic limit. In agreement with earlier results we find a
+second-order wavelike equation for the magnetic part of the Weyl tensor which
+decouples from the density gradient for the flat Friedmann universes. Assuming
+vanishing vector perturbations, including the density gradient, we find a
+similar equation for the electric part of the Weyl tensor, which was previously
+unnoticed.",1801.01147v1
+2019-04-12,"Phonon hydrodynamics, thermal conductivity and second sound in 2D crystals","Starting from our previous work where we have obtained a system of coupled
+integro-differential equations for acoustic sound waves and phonon density
+fluctuations in 2D crystals, we derive here the corresponding hydrodynamic
+equations and study their consequences as function of temperature and
+frequency. These phenomena encompass propagation and damping of acoustic sound
+waves, diffusive heat conduction, second sound and Poiseuille heat flow, all of
+which are characterized by specific transport coefficients. We calculate these
+coefficients by means of correlation functions without using the concept of
+relaxation time. Numerical calculations are performed as well in order to show
+the temperature dependence of the transport coefficients and of the thermal
+conductivity. As a consequence of thermal tension mechanical and thermal
+phenomena are coupled. We calculate the dynamic susceptibilities for
+displacement and temperature fluctuations and study their resonances. Due to
+the thermo-mechanical coupling the thermal resonances such as Landau-Placzek
+peak and second sound doublet appear in the displacement susceptibility and
+conversely the acoustic sound wave doublet appears in the temperature
+susceptibility, Our analytical results do not only apply to graphene but are
+also valid for arbitrary 2D crystals with hexagonal symmetry like 2D h-BN,
+2H-transition metal dichalcogenides and oxides.",1904.06327v1
+2020-12-17,Surface wave scattering by multiple flexible fishing cage system,"A study of the wave dynamics around a multiple fishing cage system is carried
+out under the assumption of the linear water wave theory and small-amplitude
+wave response. The Fourier--Bessel series expansion of the velocity potential
+is derived for regions enclosed under the open-water and cage systems and in
+the immediate vicinity. Further, the scattering between the cages is accounted
+for by employing Graf's addition theorem. The porous flexible cage system is
+modelled using Darcy's law and the three-dimensional membrane equation. The
+edges of the cages are moored along its circumferences to balance its position
+in the deep sea. The unknown coefficients in the potentials are obtained by
+employing the matched eigenfunction method in conjunction with the
+least-squares approximation method. In addition, the far-field scattering
+coefficients for the entire system are obtained by expanding the Bessel and
+Hankel functions in the plane wave representation form. Numerical results such
+as the hydrodynamic forces, scattering coefficients, and power dissipation are
+investigated for various cage and wave parameters. The wave loading on the cage
+system can be significantly damped by the spatial arrangement, membrane
+tension, and porous-effect parameter. Moreover, the far-field results suggest
+that the cage system can also be used as a breakwater.",2012.09522v1
+2021-01-19,Role of nucleon-nucleon correlation in transport coefficients and gravitational-wave-driven $r$-mode instability of neutron stars,"The thermal conductivity and shear viscosity of dense nuclear matter, along
+with the corresponding shear viscosity timescale of canonical neutron stars
+(NSs), are investigated, where the effect of Fermi surface depletion (i.e., the
+$Z$-factor effect) induced by the nucleon-nucleon correlation are taken into
+account. The factors which are responsible for the transport coefficients,
+including the equation of state for building the stellar structure, nucleon
+effective masses, in-medium cross sections, and the $Z$-factor at Fermi
+surfaces, are all calculated in the framework of the Brueckner theory. The
+Fermi surface depletion is found to enhance the transport coefficients by
+several times at high densities, which is more favorable to damping the
+gravitational-wave-driven $r$-mode instability of NSs. Yet, the onset of the
+$Z$-factor-quenched neutron triplet superfluidity provides the opposite
+effects, which can be much more significant than the above mentioned $Z$-factor
+effect itself. Therefore, different from the previous understanding, the
+nucleon shear viscosity is still smaller than the lepton one in the superfluid
+NS matter at low temperatures. Accordingly, the shear viscosity cannot stablize
+canonical NSs against $r$-mode oscillations even at quite low core temperatures
+$10^6$ K.",2101.07551v1
+2022-07-12,Operator growth and Krylov construction in dissipative open quantum systems,"Inspired by the universal operator growth hypothesis, we extend the formalism
+of Krylov construction in dissipative open quantum systems connected to a
+Markovian bath. Our construction is based upon the modification of the
+Liouvillian superoperator by the appropriate Lindbladian, thereby following the
+vectorized Lanczos algorithm and the Arnoldi iteration. This is well justified
+due to the incorporation of non-Hermitian effects due to the environment. We
+study the growth of Lanczos coefficients in the transverse field Ising model
+(integrable and chaotic limits) for boundary amplitude damping and bulk
+dephasing. Although the direct implementation of the Lanczos algorithm fails to
+give physically meaningful results, the Arnoldi iteration retains the generic
+nature of the integrability and chaos as well as the signature of
+non-Hermiticity through separate sets of coefficients (Arnoldi coefficients)
+even after including the dissipative environment. Our results suggest that the
+Arnoldi iteration is meaningful and more appropriate in dealing with open
+systems.",2207.05347v3
+2022-09-27,Inertio-capillary rebound of a droplet impacting a fluid bath,"The rebound of droplets impacting a deep fluid bath is studied both
+experimentally and theoretically. Millimetric drops are generated using a
+piezoelectric droplet-on-demand generator and normally impact a bath of the
+same fluid. Measurements of the droplet trajectory and other rebound metrics
+are compared directly to the predictions of a linear quasi-potential model, as
+well as fully resolved direct numerical simulations (DNS) of the unsteady
+Navier-Stokes equations. Both models resolve the time-dependent bath and
+droplet shapes in addition to the droplet trajectory. In the quasi-potential
+model, the droplet and bath shape are decomposed using orthogonal function
+decompositions leading to two sets of coupled damped linear harmonic oscillator
+equations solved using an implicit numerical method. The underdamped dynamics
+of the drop are directly coupled to the response of the bath through a
+single-point kinematic match condition which we demonstrate to be an effective
+and efficient model in our parameter regime of interest. Starting from the
+inertio-capillary limit in which both gravitational and viscous effects are
+negligible, increases in gravity or viscosity lead to a decrease in the
+coefficient of restitution and an increase in the contact time. The
+inertio-capillary limit defines an upper bound on the possible coefficient of
+restitution for droplet-bath impact, depending only on the Weber number. The
+quasi-potential model is able to rationalize historical experimental
+measurements for the coefficient of restitution, first presented by Jayaratne
+and Mason (1964).",2209.13276v2
+2017-06-28,Generating Log-normal Mock Catalog of Galaxies in Redshift Space,"We present a public code to generate a mock galaxy catalog in redshift space
+assuming a log-normal probability density function (PDF) of galaxy and matter
+density fields. We draw galaxies by Poisson-sampling the log-normal field, and
+calculate the velocity field from the linearised continuity equation of matter
+fields, assuming zero vorticity. This procedure yields a PDF of the pairwise
+velocity fields that is qualitatively similar to that of N-body simulations. We
+check fidelity of the catalog, showing that the measured two-point correlation
+function and power spectrum in real space agree with the input precisely. We
+find that a linear bias relation in the power spectrum does not guarantee a
+linear bias relation in the density contrasts, leading to a cross-correlation
+coefficient of matter and galaxies deviating from unity on small scales. We
+also find that linearising the Jacobian of the real-to-redshift space mapping
+provides a poor model for the two-point statistics in redshift space. That is,
+non-linear redshift-space distortion is dominated by non-linearity in the
+Jacobian. The power spectrum in redshift space shows a damping on small scales
+that is qualitatively similar to that of the well-known Fingers-of-God (FoG)
+effect due to random velocities, except that the log-normal mock does not
+include random velocities. This damping is a consequence of non-linearity in
+the Jacobian, and thus attributing the damping of the power spectrum solely to
+FoG, as commonly done in the literature, is misleading.",1706.09195v2
+2021-02-22,Slow-Mode Magnetoacoustic Waves in Coronal Loops,"Rapidly decaying long-period oscillations often occur in hot coronal loops of
+active regions associated with small (or micro-) flares. This kind of wave
+activity was first discovered with the SOHO/SUMER spectrometer from Doppler
+velocity measurements of hot emission lines, thus also often called ""SUMER""
+oscillations. They were mainly interpreted as global (or fundamental mode)
+standing slow magnetoacoustic waves. In addition, increasing evidence has
+suggested that the decaying harmonic type of pulsations detected in light
+curves of solar and stellar flares are likely caused by standing slow-mode
+waves. The study of slow magnetoacoustic waves in coronal loops has become a
+topic of particular interest in connection with coronal seismology. We review
+recent results from SDO/AIA and Hinode/XRT observations that have detected both
+standing and reflected intensity oscillations in hot flaring loops showing the
+physical properties (e.g., oscillation periods, decay times, and triggers) in
+accord with the SUMER oscillations. We also review recent advances in theory
+and numerical modeling of slow-mode waves focusing on the wave excitation and
+damping mechanisms. MHD simulations in 1D, 2D and 3D have been dedicated to
+understanding the physical conditions for the generation of a reflected
+propagating or a standing wave by impulsive heating. Various damping mechanisms
+and their analysis methods are summarized. Calculations based on linear theory
+suggest that the non-ideal MHD effects such as thermal conduction, compressive
+viscosity, and optically thin radiation may dominate in damping of slow-mode
+waves in coronal loops of different physical conditions. Finally, an overview
+is given of several important seismological applications such as determination
+of transport coefficients and heating function.",2102.11376v1
+2022-05-29,Modeling the Dynamics of the Coronavirus SARS-CoV-2 Pandemic using Modified SIR Model with the 'Damped-Oscillator' Dynamics of the Effective Reproduction Number,"The COVID-19 pandemic has been a great catastrophe that upended human lives
+and caused millions of deaths all over the world. The rapid spread of the
+virus, with its early-stage exponential growth and subsequent 'waves', caught
+many medical professionals and decision-makers unprepared. Even though
+epidemiological models have been known for almost a century (since the 'Spanish
+Influenza' pandemic of 1918-20), the real-life spread of the SARS-CoV-2 virus
+often confounded the modelers. While the general framework of epidemiological
+models like SEIR (susceptible-exposed-infected-recovered) or SIR
+(susceptible-exposed-infected) was not in question, the behavior of model
+parameters turned out to be unpredictable and complicated. In particular, while
+the 'basic' reproduction number, R0, can be considered a constant (for the
+original SARS-CoV-2 virus, prior to the emergence of variants, R0 is between
+2.5 and 3.0), the 'effective' reproduction number, R(t), was a complex function
+of time, influenced by human behavior in response to the pandemic (e.g.,
+masking, lockdowns, transition to remote work, etc.) To better understand these
+phenomena, we model the first year of the pandemic (between February 2020 and
+February 2021) for a number of localities (fifty US states, as well as several
+countries) using a simple SIR model. We show that the evolution of the pandemic
+can be described quite successfully by assuming that R(t) behaves in a
+'viscoelastic' manner, as a sum of two or three 'damped oscillators' with
+different natural frequencies and damping coefficients. These oscillators
+likely correspond to different sub-populations having different reactions to
+proposed mitigation measures. The proposed approach can offer future data
+modelers new ways to fit the reproduction number evolution with time (as
+compared to the purely data-driven approaches most prevalent today).",2205.14747v1
+2023-08-03,"Part I: Rebuttal to ""Uniform stabilization for the Timoshenko beam by a locally distributed damping""","A paper, entitled ""Uniform stabilization for the Timoshenko beam by a locally
+distributed damping"" was published in 2003, in the journal Electronic Journal
+of Differential Equations. Its title concerns exclusively its Section 3,
+devoted to the case of equal speeds of propagation and to its main theorem,
+namely Theorem 3.1. It states that the solutions of the Timoshenko system (see
+(1.3) in [1]) decays exponentially when the damping coefficient b is locally
+distributed. The proof of Theorem 3.1 is crucially based on Lemma 3.6, which
+states the existence of a strict Lyapunov function along which the solutions of
+(1.3) decay when the speeds of propagation are equal. This rebuttal shows the
+major gap and flaws in the proof of Lemma 3.6, which invalidate the proofs of
+Lemma 3.6 and Theorem 3.1. Lemma 3.6 is stated at the top of page 12. The main
+part of its proof is given in the pages 12 and 13. In the last eight lines of
+page 13, eight inequalities are requested to hold together for the proof of
+Lemma 3.6. They don't appear in the statements of Lemma 3.6. The subsequent
+flaws come from the evidence that several of them are contradictory either
+between them or with claims in the title of the article. We also point in this
+rebuttal other flaws, or gaps in the proofs of Theorem 2.2 related to strong
+stability and non uniform stability for the case of distinct speeds of
+propagation. In [3], we correct and complete the proof of strong stability. We
+also correct, set up the missing functional frames, fill the gaps in the proof
+of non uniform stability in the cases of different speeds of propagation, and
+complete a missing argument in the proof of Theorem A in [4] (see Remark 4.3),
+the result of Theorem A being used in the paper [1] on which this rebuttal is
+mainly devoted.",2308.01611v1
+2023-08-05,Modulating Spin Current Induced Effective Damping in $β-W/Py$ Heterostructures by a Systematic Variation in Resistivity of the Sputtered Deposited $β-W$ films,"Utilizing the spin-induced pumping from a ferromagnet (FM) into a heavy metal
+(HM) under the ferromagnetic resonance (FMR) condition, we report an
+enhancement in effective damping in $\beta$- W/Py bilayers by systematically
+varying resistivity ($\rho_{W}$) of $\beta$-W films. Different resistivity
+ranging from 100 $\mu\Omega$-cm to 1400 $\mu\Omega$-cm with a thickness of 8 nm
+can be achieved by varying the argon pressure ($P_{Ar}$) during the growth by
+the method of sputtering. The coefficient of effective damping $\alpha_{eff}$
+is observed to increase from 0.010 to 0.025 with $\rho_{W}$, which can be
+modulated by $P_{Ar}$. We observe a modest dependence of $\alpha_{eff}$ on the
+sputtering power ($p_{S}$) while keeping the $P_{Ar}$ constant. $\alpha_{eff}$
+dependence on both $P_{Ar}$ and $p_{S}$ suggests that there exists a strong
+correlation between $\alpha_{eff}$ and $\rho_{W}$. It is thus possible to
+utilize $\rho_{W}$ as a tuning parameter to regulate the $\alpha_{eff}$, which
+can be advantageous for faster magnetization dynamics switching. The thickness
+dependence study of Py in the aforementioned bilayers manifests a higher spin
+mixing conductance ($g^{\uparrow\downarrow}_{eff}$) which suggests a strong
+spin pumping from Py into the $\beta$-W layer. The effective spin current
+($J_{S(eff)}$) is also evaluated by considering the spin-back flow in this
+process. Intrinsic spin mixing conductance ($g^{\uparrow\downarrow}_{W}$) and
+spin diffusion length ($\lambda_{SD}$) of $\beta$-W are additionally
+investigated using thickness variations in $\beta$-W. Furthermore, the
+low-temperature study in $\beta$-W/Py reveals an intriguing temperature
+dependence in $\alpha_{eff}$ which is quite different from $\alpha_{b}$ of
+single Py layer and the enhancement in $\alpha_{eff}$ at low temperature can be
+attributed to the spin-induced pumping from Py layer into $\beta$-W.",2308.02939v1
+2004-05-06,On a theorem of Kac and Gilbert,"We prove a general operator theoretic result that asserts that many
+multiplicity two selfadjoint operators have simple singular spectrum.",0405110v1
+2011-01-05,Beating the Gilbert-Varshamov Bound for Online Channels,"In the online channel coding model, a sender wishes to communicate a message
+to a receiver by transmitting a codeword x =(x_1,...,x_n) in {0,1}^n bit by bit
+via a channel limited to at most pn corruptions. The channel is online in the
+sense that at the ith step the channel decides whether to flip the ith bit or
+not and its decision is based only on the bits transmitted so far, i.e.,
+(x_1,...,x_i). This is in contrast to the classical adversarial channel in
+which the corruption is chosen by a channel that has full knowledge on the sent
+codeword x. The best known lower bound on the capacity of both the online
+channel and the classical adversarial channel is the well-known
+Gilbert-Varshamov bound. In this paper we prove a lower bound on the capacity
+of the online channel which beats the Gilbert-Varshamov bound for any positive
+p such that H(2p) < 0.5 (where H is the binary entropy function). To do so, we
+prove that for any such p, a code chosen at random combined with the nearest
+neighbor decoder achieves with high probability a rate strictly higher than the
+Gilbert-Varshamov bound (for the online channel).",1101.1045v1
+2014-11-25,From heavy-tailed Boolean models to scale-free Gilbert graphs,"Define the scale-free Gilbert graph based on a Boolean model with
+heavy-tailed radius distribution on the $d$-dimensional torus by connecting two
+centers of balls by an edge if at least one of the balls contains the center of
+the other. We investigate two asymptotic properties of this graph as the size
+of the torus tends to infinity. First, we determine the tail index associated
+with the asymptotic distribution of the sum of all power-weighted incoming and
+outgoing edge lengths at a randomly chosen vertex. Second, we study the
+behavior of chemical distances on scale-free Gilbert graphs and show the
+existence of different regimes depending on the tail index of the radius
+distribution. Despite some similarities to long-range percolation and
+ultra-small scale-free geometric networks, scale-free Gilbert graphs are
+actually more closely related to fractal percolation and this connection gives
+rise to different scaling limits. We also propose a modification of the graph,
+where the total number of edges can be reduced substantially at the cost of
+introducing a logarithmic factor in the chemical distances.",1411.6824v1
+2016-03-16,Recent Results from SPLASH: Chemical Abundances and Kinematics of Andromeda's Stellar Halo,"Large scale surveys of Andromeda's resolved stellar populations have
+revolutionized our view of this galaxy over the past decade. The combination of
+large-scale, contiguous photometric surveys and pointed spectroscopic surveys
+has been particularly powerful for discovering substructure and disentangling
+the structural components of Andromeda. The SPLASH (Spectroscopic and
+Photometric Landscape of Andromeda's Stellar Halo) survey consists of broad-
+and narrow-band imaging and spectroscopy of red giant branch stars in lines of
+sight ranging in distance from 2 kpc to more than 200 kpc from Andromeda's
+center. The SPLASH data reveal a power-law surface brightness profile extending
+to at least two-thirds of Andromeda's virial radius (Gilbert et al. 2012), a
+metallicity gradient extending to at least 100 kpc from Andromeda's center
+(Gilbert et al. 2014), and evidence of a significant population of heated disk
+stars in Andromeda's inner halo (Dorman et al. 2013). We are also using the
+velocity distribution of halo stars to measure the tangential motion of
+Andromeda (Beaton et al., in prep).",1603.05160v1
+2017-05-09,Gilbert's disc model with geostatistical marking,"We study a variant of Gilbert's disc model, in which discs are positioned at
+the points of a Poisson process in $\mathbb{R}^2$ with radii determined by an
+underlying stationary and ergodic random field
+$\varphi:\mathbb{R}^2\to[0,\infty)$, independent of the Poisson process. When
+the random field is independent of the point process one often talks about
+'geostatistical marking'. We examine how typical properties of interest in
+stochastic geometry and percolation theory, such as coverage probabilities and
+the existence of long-range connections, differ between Gilbert's model with
+radii given by some random field and Gilbert's model with radii assigned
+independently, but with the same marginal distribution. Among our main
+observations we find that complete coverage of $\mathbb{R}^2$ does not
+necessarily happen simultaneously, and that the spatial dependence induced by
+the random field may both increase as well as decrease the critical threshold
+for percolation.",1705.03337v2
+2019-01-30,Is the mailing Gilbert-Steiner problem convex?,"A convexification of the mailing version of the finite Gilbert problem for
+optimal networks is introduced. It is ia convex functional on the set of
+probability measures subject to the Wasserstein $p-$ metric. The minimizer of
+this convex functional is a measure supported in a graph. If this graph is a
+tree (i.e contains no cycles) then this tree is also a minimum of the
+corresponding mailing Gilbert problem. A numerical algorithm for the
+implementation of the convexified Gilbert-mailing problem is also suggested,
+based on entropic regularization.",1901.10924v4
+2019-11-06,Phase transitions for chase-escape models on Gilbert graphs,"We present results on phase transitions of local and global survival in a
+two-species model on Gilbert graphs. At initial time there is an infection at
+the origin that propagates on the Gilbert graph according to a continuous-time
+nearest-neighbor interacting particle system. The Gilbert graph consists of
+susceptible nodes and nodes of a second type, which we call white knights. The
+infection can spread on susceptible nodes without restriction. If the infection
+reaches a white knight, this white knight starts to spread on the set of
+infected nodes according to the same mechanism, with a potentially different
+rate, giving rise to a competition of chase and escape. We show
+well-definedness of the model, isolate regimes of global survival and
+extinction of the infection and present estimates on local survival. The proofs
+rest on comparisons to the process on trees, percolation arguments and
+finite-degree approximations of the underlying random graphs.",1911.02622v2
+2019-12-13,Distance between Bound Entangled States from Unextendible Product Bases and Separable States,"We discuss the use of the Gilbert algorithm to tailor entanglement witnesses
+for unextendibleproduct basis bound entangled states (UPB BE states). The
+method relies on the fact that an optimalentanglement witness is given by a
+plane perpendicular to a line between the reference state, entanglementof which
+is to be witnessed, and its closest separable state (CSS). The Gilbert
+algorithm finds anapproximation of CSS. In this article, we investigate if this
+approximation can be good enough toyield a valid entanglement witness. We
+compare witnesses found with Gilbert algorithm and those givenby
+Bandyopadhyay-Ghosh-Roychowdhury (BGR) construction. This comparison allows us
+to learnabout the amount of entanglement and we find a relationship between it
+and a feature of the constructionof UPB BE states, namely the size of their
+central tile. We show that in most studied cases, witnessesfound with the
+Gilbert algorithm in this work are more optimal than ones obtained by
+Bandyopadhyay,Ghosh, and Roychowdhury. This result implies the increased
+tolerance to experimental imperfections ina realization of the state.",1912.06569v2
+2020-10-16,Genome organization: experiments and modelling,"This is an introduction to the special issue Genome organization: experiments
+and simulations, published in Chromosome Research, volume 25, issue 1 (2017).",2010.08464v1
+2023-10-17,Sparse grid approximation of stochastic parabolic PDEs: The Landau--Lifshitz--Gilbert equation,"We show convergence rates for a sparse grid approximation of the distribution
+of solutions of the stochastic Landau-Lifshitz-Gilbert equation. Beyond being a
+frequently studied equation in engineering and physics, the stochastic
+Landau-Lifshitz-Gilbert equation poses many interesting challenges that do not
+appear simultaneously in previous works on uncertainty quantification: The
+equation is strongly non-linear, time-dependent, and has a non-convex side
+constraint. Moreover, the parametrization of the stochastic noise features
+countably many unbounded parameters and low regularity compared to other
+elliptic and parabolic problems studied in uncertainty quantification. We use a
+novel technique to establish uniform holomorphic regularity of the
+parameter-to-solution map based on a Gronwall-type estimate and the implicit
+function theorem. This method is very general and based on a set of abstract
+assumptions. Thus, it can be applied beyond the Landau-Lifshitz-Gilbert
+equation as well. We demonstrate numerically the feasibility of approximating
+with sparse grid and show a clear advantage of a multi-level sparse grid
+scheme.",2310.11225v2
+2024-04-04,Resolving Gilbert's Conjecture: Dimensional Dependencies in Hardy Spaces Valued in Clifford Modules,"This article provides a thorough investigation into Gilbert's Conjecture,
+pertaining to Hardy spaces in the upper half-space valued in Clifford modules.
+We explore the conjecture proposed by Gilbert in 1991, which seeks to extend
+the classical principle of representing real $L^p$ functions on the real line
+as boundary values of Hardy holomorphic functions to higher-dimensional
+Euclidean spaces valued in any Clifford module. We present a complete
+resolution to this conjecture, demonstrating that its validity is contingent
+upon the dimension $n$, specifically holding true when \(n \not\equiv 6, 7 \mod
+8\) and failing otherwise. The pivotal discovery that Gilbert's conjecture can
+be reformulated as a set of algebraic conditions is underscored in this work.
+To navigate these conditions, we employ a novel strategy that leverages the
+octonions, revealing their instrumental role in addressing issues related to
+Clifford modules and spinors. This innovative approach not only provides
+explicit realization through the generalization of the Hilbert transform to the
+Riesz transform but also establishes a significant advancement in the
+understanding of Hardy spaces within higher dimensions.",2404.03478v1
+1998-02-23,Shell Effects on Rotational Damping in Superdeformed Nuclei,"Damping of rotational motion in superdeformed Hg and Dy-region nuclei is
+studied by means of cranked shell model diagonalization. It is shown that a
+shell oscillation in single-particle alignments affects significantly
+properties of rotational damping. Onset properties of damping and damping width
+for Hg are quite different from those for Dy-region superdeformed nuclei.",9802065v1
+2003-08-29,Influence of radiative damping on the optical-frequency susceptibility,"Motivated by recent discussions concerning the manner in which damping
+appears in the electric polarizability, we show that (a) there is a dependence
+of the nonresonant contribution on the damping and that (b) the damping enters
+according to the ""opposite sign prescription."" We also discuss the related
+question of how the damping rates in the polarizability are related to
+energy-level decay rates.",0309001v1
+2024-03-19,Weakly elliptic damping gives sharp decay,"We prove that weakly elliptic damping gives sharp energy decay for the
+abstract damped wave semigroup, where the damping is not in the functional
+calculus. In this case, there is no overdamping. We show applications in
+linearised water waves and Kelvin--Voigt damping.",2403.13067v1
+2019-02-25,Resonant absorption as a damping mechanism for the transverse oscillations of the coronal loops observed by SDO/AIA,"Solar coronal loops represent the variety of fast, intermediate, and slow
+normal mode oscillations. In this study, the transverse oscillations of the
+loops with a few-minutes period and also with damping caused by the resonant
+absorption were analyzed using extreme ultraviolet (EUV) images of the Sun. We
+employed the 171 $\AA$ data recorded by Solar Dynamic Observatory
+(SDO)/Atmospheric Imaging Assembly (AIA) to analyze the parameters of coronal
+loop oscillations such as period, damping time, loop length, and loop width.
+For the loop observed on 11 October 2013, the period and the damping of this
+loop are obtained to be 19 and 70 minutes, respectively. The damping quality,
+the ratio of the damping time to the period, is computed about 3.6. The period
+and damping time for the extracted loop recorded on 22 January 2013 are about
+81 and 6.79 minutes, respectively. The damping quality is also computed as 12.
+It can be concluded that the damping of the transverse oscillations of the
+loops is in the strong damping regime, so resonant absorption would be the main
+reason for the damping.",1902.09649v1
+2013-05-21,Characterization and Synthesis of Rayleigh Damped Elastodynamic Networks,"We consider damped elastodynamic networks where the damping matrix is assumed
+to be a non-negative linear combination of the stiffness and mass matrices
+(also known as Rayleigh or proportional damping). We give here a
+characterization of the frequency response of such networks. We also answer the
+synthesis question for such networks, i.e., how to construct a Rayleigh damped
+elastodynamic network with a given frequency response. Our analysis shows that
+not all damped elastodynamic networks can be realized when the proportionality
+constants between the damping matrix and the mass and stiffness matrices are
+fixed.",1305.4961v1
+2016-08-08,Damping Functions correct over-dissipation of the Smagorinsky Model,"This paper studies the time-averaged energy dissipation rate $\langle
+\varepsilon_{SMD} (u)\rangle$ for the combination of the Smagorinsky model and
+damping function. The Smagorinsky model is well known to over-damp. One common
+correction is to include damping functions that reduce the effects of model
+viscosity near walls. Mathematical analysis is given here that allows
+evaluation of $\langle \varepsilon_{SMD} (u)\rangle $ for any damping function.
+Moreover, the analysis motivates a modified van Driest damping. It is proven
+that the combination of the Smagorinsky with this modified damping function
+does not over dissipate and is also consistent with Kolmogorov phenomenology.",1608.02655v2
+2015-02-26,Efficient modelling of particle collisions using a non-linear viscoelastic contact force,"In this paper the normal collision of spherical particles is investigated.
+The particle interaction is modelled in a macroscopic way using the Hertzian
+contact force with additional linear damping. The goal of the work is to
+develop an efficient approximate solution of sufficient accuracy for this
+problem which can be used in soft-sphere collision models for Discrete Element
+Methods and for particle transport in viscous fluids. First, by the choice of
+appropriate units, the number of governing parameters of the collision process
+is reduced to one, which is a simple combination of known material parameters
+as well as initial conditions. It provides a dimensionless parameter that
+characterizes all such collisions up to dynamic similitude. Next, a rigorous
+calculation of the collision time and restitution coefficient from the
+governing equations, in the form of a series expansion in this parameter is
+provided. Such a calculation based on first principles is particularly
+interesting from a theoretical perspective. Since the governing equations
+present some technical difficulties, the methods employed are also of interest
+from the point of view of the analytical technique. Using further
+approximations, compact expressions for the restitution coefficient and the
+collision time are then provided. These are used to implement an approximate
+algebraic rule for computing the desired stiffness and damping in the framework
+of the adaptive collision model (Kempe & Fr\""{o}hlich, J. Fluid Mech., 709:
+445-489, 2012). Numerical tests with binary as well as multiple particle
+collisions are reported to illustrate the accuracy of the proposed method and
+its superiority in terms of numerical efficiency.",1502.07728v2
+2018-12-10,H$_2$/HD molecular data for analysis of quasar spectra in search of varying constants,"Absorption lines of H$_2$ and HD molecules observed at high redshift in the
+line of sight towards quasars are a test ground to search for variation of the
+proton-to-electron mass ratio $\mu$. For this purpose, results from
+astronomical observations are compared with a compilation of molecular data of
+the highest accuracy, obtained in laboratory studies as well as in
+first-principles calculations. Aims: A comprehensive line list is compiled for
+H$_2$ and HD absorption lines in the Lyman ($B^1\Sigma_u^+$ - $X^1\Sigma_g^+$)
+and Werner ($C^1\Pi_u$ - $X^1\Sigma_g^+$) band systems up to the Lyman cutoff
+at 912 Angstroms. Molecular parameters listed for each line $i$ are the
+transition wavelength $\lambda_i$, the line oscillator strength $f_i$, the
+radiative damping parameter of the excited state $\Gamma_i$, and the
+sensitivity coefficient $K_i$ for a variation of the proton-to-electron mass
+ratio. Methods: The transition wavelengths $\lambda_i$ for the H$_2$ and HD
+molecules are determined by a variety of advanced high-precision spectroscopic
+experiments involving narrowband vacuum ultraviolet lasers, Fourier-transform
+spectrometers, and synchrotron radiation sources. Results for the line
+oscillator strengths $f_i$, damping parameters $\Gamma_i$, and sensitivity
+coefficients $K_i$ are obtained in theoretical quantum chemical calculations.
+Results: A new list of molecular data is compiled for future analyses of cold
+clouds of hydrogen absorbers, specifically for studies of $\mu$-variation from
+quasar data. The list is applied in a refit of quasar absorption spectra of
+B0642$-$5038 and J1237$+$0647 yielding constraints on a variation of the
+proton-to-electron mass ratio $\Delta\mu/\mu$ consistent with previous
+analyses.",1812.03628v2
+2019-12-24,Modified Drude model for small gold nanoparticles surface plasmon resonance based on the role of classical confinement,"We study the effect of restoration force caused by the limited size of a
+small metallic nanoparticle (MNP) on its linear response to the electric field
+of incident light. In a semi-classical phenomenological Drude-like model for
+small MNP, we consider restoration force caused by the displacement of
+conduction electrons with respect to the ionic background taking into account a
+free coefficient as a function of diameter of NP in the force term obtained by
+the idealistic Thomson model in order to adjust the classical approach. All
+important mechanisms of the energy dissipation such as electron-electron,
+electron-phonon and electron-NP surface scatterings and radiation are included
+in the model. In addition a correction term added to the damping factor of
+mentioned mechanisms in order to rectify the deficiencies of theoretical
+approaches. To determine the free parameters, the experimental data of
+extinction cross section of gold NPs with different sizes doped in the glass
+are used and a good agreement between experimental data and our model is
+observed. It is shown that by decreasing the diameter of NP, the restoration
+force becomes larger and classical confinement effect becomes more dominant in
+the interaction. According to experimental data, the best fitted parameter for
+the coefficient of restoration force is a third order negative powers function
+of diameter. The fitted function for the correction damping factor is
+proportional to the inverse squared wavelength and third order power series of
+NP diameter. The real and imaginary parts of permittivity for different sizes
+of gold NPs are presented and it is seen that the imaginary part is more
+sensitive to the diameter variations. Increase in the NP diameter causes
+increase in the real part of permittivity and decrease in the imaginary part.",1912.11245v1
+2022-01-03,"Solid-like to Liquid-like Behavior of Cu Diffusion in Superionic Cu2X (X=S, Se): An Inelastic Neutron Scattering and Ab-Initio Molecular Dynamics Investigation","Cu2Se and Cu2S are excellent model systems of superionic conductors with
+large diffusion coefficients that have been reported to exhibit different
+solid-liquid-like Cu-ion diffusion. In this paper, we clarify the atomic
+dynamics of these compounds with temperature-dependent ab-initio molecular
+dynamics (AIMD) simulations and inelastic neutron scattering (INS) experiments.
+Using the dynamical structure factor and Van-Hove correlation function, we
+interrogate the jump-time, hopping length distribution and associated diffusion
+coefficients. In cubic-Cu2Se at 500 K, we find solid-like diffusion with
+Cu-jump lengths matching well the first-neighbour Cu-Cu distance of ~3 {\AA} in
+the crystal, and clearly defined optic phonons involving Cu-vibrations. Above
+700 K, the jump-length distribution becomes a broad maximum cantered around 4
+{\AA}, spanning the first and second neighbour lattice distances, and a
+concurrent broadening of the Cu-phonon density of states. Further, above 900 K,
+the Cu-diffusion becomes close to liquid-like, with distributions of Cu-atoms
+continuously connecting crystal sites, while the vibrational modes involving Cu
+motions are highly damped, though still not fully over-damped as in a liquid.
+At low temperatures, the solid-like diffusion is consistent with previous X-ray
+diffraction and quasielastic neutron scattering experiments, while the
+higher-temperature observation of the liquid-like diffusion is in agreement
+with previous AIMD simulations. We also report AIMD simulations in Cu2S in the
+hexagonal and cubic superionic phases, and observe similar solid and
+liquid-like diffusion at low- and high-temperatures, respectively. The
+calculated ionic-conductivity is in fair agreement with reported experimental
+values.",2201.00606v1
+2024-02-22,Laser patterning of magnonic structure via local crystallization of Yittrium Iron Garnet,"The fabrication and integration of high-quality structures of Yttrium Iron
+Garnet (YIG) is critical for magnonics.Films with excellent properties are
+obtained only on single crystal Gadolinium Gallium Garnet (GGG) substrates
+using high-temperature processes. The subsequent realization of magnonic
+structures via lithography and etching is not straightforward as it requires a
+tight control of the edge roughness, to avoid magnon scattering, and
+planarization in case of multilayer devices. In this work we describe a
+different approach based on local laser annealing of amorphous YIG films,
+avoiding the need for subjecting the entire sample to high thermal budgets and
+for physical etching. Starting from amorphous and paramagnetic YIG films grown
+by pulsed laser deposition at room temperature on GGG, a 405 nm laser is used
+for patterning arbitrary shaped ferrimagnetic structures by local
+crystallization. In thick films (160 nm) the laser induced surface corrugation
+prevents the propagation of spin-wave modes in patterned conduits. For thinner
+films (80 nm) coherent propagation is observed in 1.2 micron wide conduits
+displaying an attenuation length of 5 micron which is compatible with a damping
+coefficient of about 5e-3. Possible routes to achieve damping coefficients
+compatible with state-of-the art epitaxial YIG films are discussed.",2402.14444v1
+2024-03-07,The stochastic Ravine accelerated gradient method with general extrapolation coefficients,"In a real Hilbert space domain setting, we study the convergence properties
+of the stochastic Ravine accelerated gradient method for convex differentiable
+optimization. We consider the general form of this algorithm where the
+extrapolation coefficients can vary with each iteration, and where the
+evaluation of the gradient is subject to random errors. This general treatment
+models a breadth of practical algorithms and numerical implementations. We show
+that, under a proper tuning of the extrapolation parameters, and when the error
+variance associated with the gradient evaluations or the step-size sequences
+vanish sufficiently fast, the Ravine method provides fast convergence of the
+values both in expectation and almost surely. We also improve the convergence
+rates from O(.) to o(.). Moreover, we show almost sure summability property of
+the gradients, which implies the fast convergence of the gradients towards
+zero. This property reflects the fact that the high-resolution ODE of the
+Ravine method includes a Hessian-driven damping term. When the space is also
+separable, our analysis allows also to establish almost sure weak convergence
+of the sequence of iterates provided by the algorithm. We finally specialize
+the analysis to consider different parameter choices, including vanishing and
+constant (heavy ball method with friction) damping parameter, and present a
+comprehensive landscape of the tradeoffs in speed and accuracy associated with
+these parameter choices and statistical properties on the sequence of errors in
+the gradient computations. We provide a thorough discussion of the similarities
+and differences with the Nesterov accelerated gradient which satisfies similar
+asymptotic convergence rates.",2403.04860v2
+2012-01-27,Full and Half Gilbert Tessellations with Rectangular Cells,"We investigate the ray-length distributions for two different rectangular
+versions of Gilbert's tessellation. In the full rectangular version, lines
+extend either horizontally (with east- and west-growing rays) or vertically
+(north- and south-growing rays) from seed points which form a Poisson point
+process, each ray stopping when another ray is met. In the half rectangular
+version, east and south growing rays do not interact with west and north rays.
+For the half rectangular tessellation we compute analytically, via recursion, a
+series expansion for the ray-length distribution, whilst for the full
+rectangular version we develop an accurate simulation technique, based in part
+on the stopping-set theory of Zuyev, to accomplish the same. We demonstrate the
+remarkable fact that plots of the two distributions appear to be identical when
+the intensity of seeds in the half model is twice that in the full model. Our
+paper explores this coincidence mindful of the fact that, for one model, our
+results are from a simulation (with inherent sampling error). We go on to
+develop further analytic theory for the half-Gilbert model using stopping-set
+ideas once again, with some novel features. Using our theory, we obtain exact
+expressions for the first and second moment of ray length in the half-Gilbert
+model. For all practical purposes, these results can be applied to the
+full-Gilbert model as much better approximations than those provided by
+Mackissack and Miles.",1201.5780v1
+2021-06-08,On numerical aspects of parameter identification for the Landau-Lifshitz-Gilbert equation in Magnetic Particle Imaging,"The Landau-Lifshitz-Gilbert equation yields a mathematical model to describe
+the evolution of the magnetization of a magnetic material, particularly in
+response to an external applied magnetic field. It allows one to take into
+account various physical effects, such as the exchange within the magnetic
+material itself. In particular, the Landau-Lifshitz-Gilbert equation encodes
+relaxation effects, i.e., it describes the time-delayed alignment of the
+magnetization field with an external magnetic field. These relaxation effects
+are an important aspect in magnetic particle imaging, particularly in the
+calibration process. In this article, we address the data-driven modeling of
+the system function in magnetic particle imaging, where the
+Landau-Lifshitz-Gilbert equation serves as the basic tool to include relaxation
+effects in the model. We formulate the respective parameter identification
+problem both in the all-at-once and the reduced setting, present reconstruction
+algorithms that yield a regularized solution and discuss numerical experiments.
+Apart from that, we propose a practical numerical solver to the nonlinear
+Landau-Lifshitz-Gilbert equation, not via the classical finite element method,
+but through solving only linear PDEs in an inverse problem framework.",2106.07625v1
+2021-01-28,"Fluid-elastic coefficients in single phase cross flow: dimensional analysis, direct and indirect experimental methods","The importance of fluid-elastic forces in tube bundle vibrations can hardly
+be over-emphasized, in view of their damaging potential. In the last decades,
+advanced models for representing fluid-elastic coupling have therefore been
+developed by the community of the domain. Those models are nowadays embedded in
+the methodologies that are used on a regular basis by both steam generators
+providers and operators, in order to prevent the risk of a tube failure with
+adequate safety margins. From an R&D point of view however, the need still
+remains for more advanced models of fluid-elastic coupling, in order to fully
+decipher the physics underlying the observed phenomena. As a consequence, new
+experimental flow-coupling coefficients are also required to specifically feed
+and validate those more sophisticated models. Recent experiments performed at
+CEA-Saclay suggest that the fluid stiffness and damping coefficients depend on
+further dimensionless parameters beyond the reduced velocity.
+  In this work, the problem of data reduction is first revisited, in the light
+of dimensional analysis. For single-phase flows, it is underlined that the
+flow-coupling coefficients depend at least on two dimensionless parameters,
+namely the Reynolds number $Re$ and the Stokes number $Sk$. Therefore, reducing
+the experimental data in terms of the compound dimensionless quantity
+$V_r=Re/Sk$ necessarily leads to impoverish results, hence the data dispersion.
+In a second step, experimental data are presented using the dimensionless
+numbers $Re$ and $Sk$. We report experiments, for a 3x5 square tube bundle
+subjected to water transverse flow. The bundle is rigid, except for the central
+tube which is mounted on a flexible suspension allowing for translation motions
+in the lift direction.",2101.12021v1
+2000-09-11,Numerical Studies on Locally Damped Structures,"In the JLC/NLC X-band linear collider, it is essential to reduce the
+long-range dipole wakefields in the accelerator structure to prevent beam break
+up (BBU) and emittance degradation. The two methods of reducing the long-range
+wakefields are detuning and damping. Detuning reduces the wakefields rapidly as
+the dipole modes de-cohere but, with a finite number of modes, the wakefield
+will grow again as the modes re-cohere. In contrast, damping suppresses the
+wakefields at a longer distance. There are two principal damping schemes:
+synchronous damping using HOM manifolds such as that used in the RDDS1
+structure and local damping similar to that used in the CLIC structure. In a
+locally damped scheme, one can obtain almost any Q value, however, the damping
+can have significant effects on the accelerating mode. In this paper, we
+present a medium local-damping scheme where the wakefields are controlled to
+meet the BBU requirement while minimizing the degradations of the fundamental
+rf parameters. We will address the load design and pulse heating issues
+associated with the medium damping scheme.",0009039v1
+2015-03-13,A one-step optimal energy decay formula for indirectly nonlinearly damped hyperbolic systems coupled by velocities,"In this paper, we consider the energy decay of a damped hyperbolic system of
+wave-wave type which is coupled through the velocities. We are interested in
+the asymptotic properties of the solutions of this system in the case of
+indirect nonlinear damping, i.e. when only one equation is directly damped by a
+nonlinear damping. We prove that the total energy of the whole system decays as
+fast as the damped single equation. Moreover, we give a one-step general
+explicit decay formula for arbitrary nonlinearity. Our results shows that the
+damping properties are fully transferred from the damped equation to the
+undamped one by the coupling in velocities, different from the case of
+couplings through displacements as shown in \cite{AB01, ACK01, AB02, AL12} for
+the linear damping case, and in \cite{AB07} for the nonlinear damping case. The
+proofs of our results are based on multiplier techniques, weighted nonlinear
+integral inequalities and the optimal-weight convexity method of \cite{AB05,
+AB10}.",1503.04126v1
+2015-08-21,Radiative damping in wave guide based FMR measured via analysis of perpendicular standing spin waves in sputtered Permalloy films,"The damping $\alpha$ of the spinwave resonances in 75 nm, 120 nm, and 200nm
+-thick Permalloy films is measured via vector-network-analyzer
+ferromagnetic-resonance (VNA-FMR) in the out-of-plane geometry. Inductive
+coupling between the sample and the waveguide leads to an additional radiative
+damping term. The radiative contribution to the over-all damping is determined
+by measuring perpendicular standing spin waves (PSSWs) in the Permalloy films,
+and the results are compared to a simple analytical model. The damping of the
+PSSWs can be fully explained by three contributions to the damping: The
+intrinsic damping, the eddy-current damping, and the radiative damping. No
+other contributions were observed. Furthermore, a method to determine the
+radiative damping in FMR measurements with a single resonance is suggested.",1508.05265v1
+2022-09-28,Tunable nonlinear damping in parametric regime,"Nonlinear damping plays a significant role in several area of physics and it
+is becoming increasingly important to understand its underlying mechanism.
+However, microscopic origin of nonlinear damping is still a debatable topic.
+Here, we probe and report nonlinear damping in a highly tunable MoS2 nano
+mechanical drum resonator using electrical homodyne actuation and detection
+technique. In our experiment, we achieve 2:1 internal resonance by tuning
+resonance frequency and observe enhanced non-linear damping. We probe the
+effect of non-linear damping by characterizing parametric gain. Geometry and
+tunability of the device allow us to reduce the effect of other prominent
+Duffing non-linearity to probe the non-linear damping effectively. The enhanced
+non-linear damping in the vicinity of internal resonance is also observed in
+direct drive, supporting possible origin of non-linear damping. Our experiment
+demonstrates, a highly tunable 2D material based nanoresonator offers an
+excellent platform to study the nonlinear physics and exploit nonlinear damping
+in parametric regime.",2209.14120v1
+2005-11-07,The Effects of Alfven Waves and Radiation Pressure in Dusty Winds of Late-Type Stars. II. Dust-Cyclotron Damping,"There are in the literature several theories to explain the mass loss in
+stellar winds. In particular, for late-type stars, some authors have proposed a
+wind model driven by an outward-directed flux of damped Alfven waves. The winds
+of these stars present great amounts of dust particles that, if charged, can
+give rise to new wave modes or modify the pre-existing ones. In this work, we
+study how the dust can affect the propagation of Alfven waves in these winds
+taking into account a specific damping mechanism, dust-cyclotron damping. This
+damping affects the Alfven wave propagation near the dust-cyclotron frequency.
+Hence, if we assume a dust size distribution, the damping occurs over a broad
+band of wave frequencies. In this work, we present a model of Alfven
+wave-driven winds using the dust-cyclotron damping mechanism. On the basis of
+coronal holes in the Sun, which present a superradial expansion, our model also
+assumes a diverging geometry for the magnetic field. Thus, the mass, momentum,
+and energy equations are obtained and then solved in a self-consistent
+approach. Our results of wind velocity and temperature profiles for a typical
+K5 supergiant star shows compatibility with observations. We also show that,
+considering the presence of charged dust particles, the wave flux is less
+damped due to the dust-cyclotron damping than it would be if we consider some
+other damping mechanisms studied in the literature, such as nonlinear damping,
+resonant surface damping, and turbulent damping.",0511192v2
+2013-09-11,Initial versus tangent stiffness-based Rayleigh damping in inelastic time history seismic analyses,"In the inelastic time history analyses of structures in seismic motion, part
+of the seismic energy that is imparted to the structure is absorbed by the
+inelastic structural model, and Rayleigh damping is commonly used in practice
+as an additional energy dissipation source. It has been acknowledged that
+Rayleigh damping models lack physical consistency and that, in turn, it must be
+carefully used to avoid encountering unintended consequences as the appearance
+of artificial damping. There are concerns raised by the mass proportional part
+of Rayleigh damping, but they are not considered in this paper. As far as the
+stiffness proportional part of Rayleigh damping is concerned, either the
+initial structural stiffness or the updated tangent stiffness can be used. The
+objective of this paper is to provide a comprehensive comparison of these two
+types of Rayleigh damping models so that a practitioner (i) can objectively
+choose the type of Rayleigh damping model that best fits her/his needs and (ii)
+is provided with useful analytical tools to design Rayleigh damping model with
+good control on the damping ratios throughout inelastic analysis. To that end,
+a review of the literature dedicated to Rayleigh damping within these last two
+decades is first presented; then, practical tools to control the modal damping
+ratios throughout the time history analysis are developed; a simple example is
+finally used to illustrate the differences resulting from the use of either
+initial or tangent stiffness-based Rayleigh damping model.",1309.2741v1
+2017-07-14,Damping of gravitational waves by matter,"We develop a unified description, via the Boltzmann equation, of damping of
+gravitational waves by matter, incorporating collisions. We identify two
+physically distinct damping mechanisms -- collisional and Landau damping. We
+first consider damping in flat spacetime, and then generalize the results to
+allow for cosmological expansion. In the first regime, maximal collisional
+damping of a gravitational wave, independent of the details of the collisions
+in the matter is, as we show, significant only when its wavelength is
+comparable to the size of the horizon. Thus damping by intergalactic or
+interstellar matter for all but primordial gravitational radiation can be
+neglected. Although collisions in matter lead to a shear viscosity, they also
+act to erase anisotropic stresses, thus suppressing the damping of
+gravitational waves. Damping of primordial gravitational waves remains
+possible. We generalize Weinberg's calculation of gravitational wave damping,
+now including collisions and particles of finite mass, and interpret the
+collisionless limit in terms of Landau damping. While Landau damping of
+gravitational waves cannot occur in flat spacetime, the expansion of the
+universe allows such damping by spreading the frequency of a gravitational wave
+of given wavevector.",1707.05192v2
+2003-04-10,Electron-Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. VII. Relativistic calculations for O VI and O VII for UV and X-ray modeling,"Aimed at ionization balance and spectral analysis of UV and X-ray sources, we
+present self-consistent sets of photoionization cross sections, recombination
+cross sections, and rate coefficients for Li-like O VI and He-like O VII.
+Relativistic fine structure is considered through the Breit-Pauli R-matrix
+(BPRM) method in the close coupling approximation, implementing the unified
+treatment for total electron-ion recombination subsuming both radiative and
+di-electronic recombination processes. Self-consistency is ensured by using an
+identical wavefunction expansion for the inverse processes of photoionization
+and photo-recombination. Radiation damping of resonances, important for H-like
+and He-like core ions, is included. Compared to previous LS coupling results
+without radiative decay of low-n (<= 10) resonances, the presents results show
+significant reduction in O VI recombination rates at high temperatures. In
+addition to the total rates, level-specific photoionization cross sections and
+recombination rates are presented for all fine structure levels n (lSLJ) up to
+n <= 10, to enable accurate computation of recombination-cascade matrices and
+spectral formation of prominent UV and X-ray lines such as the 1032,1038 A
+doublet of O VI, and the `triplet' forbidden, intercombination, and resonance
+X-ray lines of O VII at 22.1, 21.8, and 21.6 \ang respectively. Altogether,
+atomic parameters for 98 levels of O VI and 116 fine structure levels of O VII
+are theoretically computed. These data should provide a reasonably complete set
+of photoionization and recombination rates in collisional or radiative
+equilibrium.",0304204v1
+2013-07-25,Relaxation of Bose-Einstein Condensates of Magnons in Magneto-Textural Traps in Superfluid $^3$He-B,"In superfluid $^3$He-B externally pumped quantized spin-wave excitations or
+magnons spontaneously form a Bose-Einstein condensate in a 3-dimensional trap
+created with the order-parameter texture and a shallow minimum in the
+polarizing field. The condensation is manifested by coherent precession of the
+magnetization with a common frequency in a large volume. The trap shape is
+controlled by the profile of the applied magnetic field and by the condensate
+itself via the spin-orbit interaction. The trapping potential can be
+experimentally determined with the spectroscopy of the magnon levels in the
+trap. We have measured the decay of the ground state condensates after
+switching off the pumping in the temperature range $(0.14\div
+0.2)T_{\mathrm{c}}$. Two contributions to the relaxation are identified: (1)
+spin-diffusion with the diffusion coefficient proportional to the density of
+thermal quasiparticles and (2) the approximately temperature-independent
+radiation damping caused by the losses in the NMR pick-up circuit. The measured
+dependence of the relaxation on the shape of the trapping potential is in a
+good agreement with our calculations based on the magnetic field profile and
+the magnon-modified texture. Our values for the spin diffusion coefficient at
+low temperatures agree with the theoretical prediction and earlier measurements
+at temperatures above $0.5T_{\mathrm{c}}$.",1307.6782v2
+2014-01-07,Spectral parameter power series for polynomial pencils of Sturm-Liouville operators and Zakharov-Shabat systems,"A spectral parameter power series (SPPS) representation for solutions of
+Sturm-Liouville equations of the form
+$$(pu')'+qu=u\sum_{k=1}^{N}\lambda^{k}r_{k}$$ is obtained. It allows one to
+write a general solution of the equation as a power series in terms of the
+spectral parameter $\lambda$. The coefficients of the series are given in terms
+of recursive integrals involving a particular solution of the equation
+$(pu_{0}')'+qu_{0}=0$. The convenient form of the solution provides an
+efficient numerical method for solving corresponding initial value, boundary
+value and spectral problems.
+  A special case of the considered Sturm-Liouville equation arises in relation
+with the Zakharov-Shabat system. We derive an SPPS representation for its
+general solution and consider other applications as the one-dimensional Dirac
+system and the equation describing a damped string. Several numerical examples
+illustrate the efficiency and the accuracy of the numerical method based on the
+SPPS representations which besides its natural advantages like the simplicity
+in implementation and accuracy is applicable to the problems admitting complex
+coefficients, spectral parameter dependent boundary conditions and complex
+spectrum.",1401.1520v1
+2016-11-29,Derivation of a generalized Schrödinger equation from the theory of scale relativity,"Using Nottale's theory of scale relativity relying on a fractal space-time,
+we derive a generalized Schr\""odinger equation taking into account the
+interaction of the system with the external environment. This equation
+describes the irreversible evolution of the system towards a static quantum
+state. We first interpret the scale-covariant equation of dynamics stemming
+from Nottale's theory as a hydrodynamic viscous Burgers equation for a
+potential flow involving a complex velocity field and an imaginary viscosity.
+We show that the Schr\""odinger equation can be directly obtained from this
+equation by performing a Cole-Hopf transformation equivalent to the WKB
+transformation. We then introduce a friction force proportional and opposite to
+the complex velocity in the scale-covariant equation of dynamics in a way that
+preserves the local conservation of the normalization condition. We find that
+the resulting generalized Schr\""odinger equation, or the corresponding fluid
+equations obtained from the Madelung transformation, involve not only a damping
+term but also an effective thermal term. The friction coefficient and the
+temperature are related to the real and imaginary parts of the complex friction
+coefficient in the scale-covariant equation of dynamics. This may be viewed as
+a form of fluctuation-dissipation theorem. We show that our generalized
+Schr\""odinger equation satisfies an $H$-theorem for the quantum Boltzmann free
+energy. As a result, the probability distribution relaxes towards an
+equilibrium state which can be viewed as a Boltzmann distribution including a
+quantum potential. We propose to apply this generalized Schr\""odinger equation
+to dark matter halos in the Universe, possibly made of self-gravitating
+Bose-Einstein condensates.",1612.02323v1
+2016-12-08,Robust identification of harmonic oscillator parameters using the adjoint Fokker-Planck equation,"We present a model-based output-only method for identifying from time series
+the parameters governing the dynamics of stochastically forced oscillators. In
+this context, suitable models of the oscillator's damping and stiffness
+properties are postulated, guided by physical understanding of the oscillatory
+phenomena. The temporal dynamics and the probability density function of the
+oscillation amplitude are described by a Langevin equation and its associated
+Fokker-Planck equation, respectively. One method consists in fitting the
+postulated analytical drift and diffusion coefficients with their estimated
+values, obtained from data processing by taking the short-time limit of the
+first two transition moments. However, this limit estimation loses robustness
+in some situations - for instance when the data is band-pass filtered to
+isolate the spectral contents of the oscillatory phenomena of interest. In this
+paper, we use a robust alternative where the adjoint Fokker-Planck equation is
+solved to compute Kramers-Moyal coefficients exactly, and an iterative
+optimisation yields the parameters that best fit the observed statistics
+simultaneously in a wide range of amplitudes and time scales. The method is
+illustrated with a stochastic Van der Pol oscillator serving as a prototypical
+model of thermoacoustic instabilities in practical combustors, where system
+identification is highly relevant to control.",1612.02579v1
+2017-06-19,Derivation of a generalized Schrödinger equation for dark matter halos from the theory of scale relativity,"Using Nottale's theory of scale relativity, we derive a generalized
+Schr\""odinger equation applying to dark matter halos. This equation involves a
+logarithmic nonlinearity associated with an effective temperature and a source
+of dissipation. Fundamentally, this wave equation arises from the
+nondifferentiability of the trajectories of the dark matter particles whose
+origin may be due to ordinary quantum mechanics, classical ergodic (or almost
+ergodic) chaos, or to the fractal nature of spacetime at the cosmic scale. The
+generalized Schr\""odinger equation involves a coefficient ${\cal D}$, possibly
+different from $\hbar/2m$, whose value for dark matter halos is ${\cal
+D}=1.02\times 10^{23}\, {\rm m^2/s}$. We suggest that the cold dark matter
+crisis may be solved by the fractal (nondifferentiable) structure of spacetime
+at the cosmic scale, or by the chaotic motion of the particles on a very long
+timescale, instead of ordinary quantum mechanics. The equilibrium states of the
+generalized Schr\""odinger equation correspond to configurations with a
+core-halo structure. The quantumlike potential generates a solitonic core that
+solves the cusp problem of the classical cold dark matter model. The
+logarithmic nonlinearity accounts for the presence of an isothermal halo that
+leads to flat rotation curves. The damping term ensures that the system relaxes
+towards an equilibrium state. This property is guaranteed by an $H$-theorem
+satisfied by a Boltzmann-like free energy functional. In our approach, the
+temperature and the friction arise from a single formalism. They correspond to
+the real and imaginary parts of the complex friction coefficient present in the
+scale covariant equation of dynamics that is at the basis of Nottale's theory
+of scale relativity.",1706.05900v2
+2017-06-21,Spectral analysis and multigrid preconditioners for two-dimensional space-fractional diffusion equations,"Fractional diffusion equations (FDEs) are a mathematical tool used for
+describing some special diffusion phenomena arising in many different
+applications like porous media and computational finance. In this paper, we
+focus on a two-dimensional space-FDE problem discretized by means of a second
+order finite difference scheme obtained as combination of the Crank-Nicolson
+scheme and the so-called weighted and shifted Gr\""unwald formula.
+  By fully exploiting the Toeplitz-like structure of the resulting linear
+system, we provide a detailed spectral analysis of the coefficient matrix at
+each time step, both in the case of constant and variable diffusion
+coefficients. Such a spectral analysis has a very crucial role, since it can be
+used for designing fast and robust iterative solvers. In particular, we employ
+the obtained spectral information to define a Galerkin multigrid method based
+on the classical linear interpolation as grid transfer operator and
+damped-Jacobi as smoother, and to prove the linear convergence rate of the
+corresponding two-grid method. The theoretical analysis suggests that the
+proposed grid transfer operator is strong enough for working also with the
+V-cycle method and the geometric multigrid. On this basis, we introduce two
+computationally favourable variants of the proposed multigrid method and we use
+them as preconditioners for Krylov methods. Several numerical results confirm
+that the resulting preconditioning strategies still keep a linear convergence
+rate.",1706.06844v1
+2018-02-03,Origin of the size-dependence of the equilibrium van der Waals binding between nanostructures,"Nanostructures can be bound together at equilibrium by the van der Waals
+(vdW) effect, a small but ubiquitous many-body attraction that presents
+challenges to density functional theory. How does the binding energy depend
+upon the size or number of atoms in one of a pair of identical nanostructures?
+To answer this question, we treat each nanostructure properly as a whole
+object, not as a collection of atoms. Our calculations start from an accurate
+static dipole polarizability for each considered nanostructure, and an accurate
+equilibrium center-to-center distance for the pair (the latter from experiment,
+or from the vdW-DF-cx functional). We consider the competition in each term
+$-C_{2k}/d^{2k}$ ($k=3, 4, 5$) of the long-range vdW series for the interaction
+energy, between the size dependence of the vdW coefficient $C_{2k}$ and that of
+the $2k$-th power of the center-to-center distance $d$. The damping of these
+vdW terms can be negligible, but in any case it does not affect the size
+dependence for a given term in the absence of non-vdW binding. To our surprise,
+the vdW energy can be size-independent for quasi-spherical nanoclusters bound
+to one another by vdW interaction, even with strong nonadditivity of the vdW
+coefficient, as demonstrated for fullerenes. We also show that, for
+low-dimensional systems, the vdW interaction yields the strongest
+size-dependence, in stark contrast to that of fullerenes. We illustrate this
+with parallel planar polycyclic aromatic hydrocarbons. Other cases are between,
+as shown by sodium clusters.",1802.00975v1
+2018-04-12,System-size dependence of the viscous attenuation of anisotropic flow in p+Pb and Pb+Pb collisions at LHC energies,"The elliptic and triangular flow coefficients ($\mathrm{v_n, \, n=2,3}$)
+measured in Pb+Pb ($\sqrt{s_{_{\rm NN}}} = 2.76$ TeV) and p+Pb ($\sqrt{s_{_{\rm
+NN}}} = 5.02$ TeV) collisions, are studied as a function of initial-state
+eccentricity ($\varepsilon_n$), and dimensionless size characterized by the
+cube root of the mid-rapidity charged hadron multiplicity density
+$\mathrm{\left< N_{ch} \right>^{1/3}}$. The results indicate that the influence
+of eccentricity ($\mathrm{v_n} \propto \varepsilon_n$) observed for large
+$\mathrm{\left< N_{ch} \right>}$, is superseded by the effects of viscous
+attenuation for small $\mathrm{\left< N_{ch} \right>}$, irrespective of the
+colliding species. Strikingly similar acoustic scaling patterns of exponential
+viscous modulation, with a damping rate proportional to $\mathrm{n^2}$ and
+inversely proportional to the dimensionless size, are observed for the
+eccentricity-scaled coefficients for the two sets of colliding species. The
+resulting scaling parameters suggest that, contrary to current predilections,
+the patterns of viscous attenuation, as well as the specific shear viscosity
+$\left<\frac{\eta}{s}(\text{T})\right>$ for the matter created in p+Pb and
+Pb+Pb collisions, are comparable.",1804.04618v3
+2019-03-04,Role of geometrical cues in neuronal growth,"Geometrical cues play an essential role in neuronal growth. Here, we quantify
+axonal growth on surfaces with controlled geometries and report a general
+stochastic approach that quantitatively describes the motion of growth cones.
+We show that axons display a strong directional alignment on micro-patterned
+surfaces when the periodicity of the patterns matches the dimension of the
+growth cone. The growth cone dynamics on surfaces with uniform geometry is
+described by a linear Langevin equation with both deterministic and stochastic
+contributions. In contrast, axonal growth on surfaces with periodic patterns is
+characterized by a system of two generalized Langevin equations with both
+linear and quadratic velocity dependence and stochastic noise. We combine
+experimental data with theoretical analysis to measure the key parameters of
+the growth cone motion: angular distributions, correlation functions, diffusion
+coefficients, characteristics speeds and damping coefficients. We demonstrate
+that axonal dynamics displays a cross-over from an Ornstein-Uhlenbeck process
+to a non-linear stochastic regime when the geometrical periodicity of the
+pattern approaches the linear dimension of the growth cone. Growth alignment is
+determined by surface geometry, which is fully quantified by the deterministic
+part of the Langevin equation. These results provide new insight into the role
+of curvature sensing proteins and their interactions with geometrical cues.",1903.01337v2
+2019-05-07,On the reduction of required motions in the dynamic analysis using an optimization-based spectral matching,"This study aims to show the efficiency of a proposed spectral matching
+technique for the reduction of required ground motions in the dynamic time
+history analysis. In this non-stationary spectral matching approach,
+unconstrained optimization is employed to adjust the signal to match a target
+spectrum. Adjustment factors of discrete wavelet transform (DWT) coefficients
+associated with the signals are then considered as decision variables and the
+Levenberg-Marquardt algorithm is employed to find the optimum values of DWT
+coefficients. This matching algorithm turns out to be quite effective in the
+spectral matching objective, where matching at multiple damping ratios can be
+readily achieved. First, the efficiency of the spectral matching procedure is
+investigated in a case study earthquake record and then compared with two
+conventional spectral matching methods. Results show considerable improvement
+in the matching accuracy which is accompanied by minimal changes in shaking
+characteristics of the original signal. In addition, it is shown that
+earthquake records matched with the proposed method can noticeably reduce the
+essential number of ground motions that are normally required for the dynamic
+analysis of a case study model. In this regard, it has been found that we can
+reduce the number of required motions by more than 80% when matched motions are
+selected to be used as the seismic inputs for the dynamic analysis.",1905.02394v4
+2019-06-11,Anomalous diffusion for neuronal growth on surfaces with controlled geometries,"Geometrical cues are known to play a very important role in neuronal growth
+and the formation of neuronal networks. Here, we present a detailed analysis of
+axonal growth and dynamics for neuronal cells cultured on patterned
+polydimethylsiloxane surfaces. We use fluorescence microscopy to image neurons,
+quantify their dynamics, and demonstrate that the substrate geometrical
+patterns cause strong directional alignment of axons. We quantify axonal growth
+and report a general stochastic approach that quantitatively describes the
+motion of growth cones. The growth cone dynamics is described by Langevin and
+Fokker-Planck equations with both deterministic and stochastic contributions.
+We show that the deterministic terms contain both the angular and speed
+dependence of axonal growth, and that these two contributions can be separated.
+Growth alignment is determined by surface geometry, and it is quantified by the
+deterministic part of the Langevin equation. We combine experimental data with
+theoretical analysis to measure the key parameters of the growth cone motion:
+speed and angular distributions, correlation functions, diffusion coefficients,
+characteristics speeds and damping coefficients. We demonstrate that axonal
+dynamics displays a cross-over from Brownian motion (Ornstein-Uhlenbeck
+process) at earlier times to anomalous dynamics (superdiffusion) at later
+times. The superdiffusive regime is characterized by non-Gaussian speed
+distributions and power law dependence of the axonal mean square length and the
+velocity correlation functions. These results demonstrate the importance of
+geometrical cues in guiding axonal growth, and could lead to new methods for
+bioengineering novel substrates for controlling neuronal growth and
+regeneration.",1906.05679v1
+2019-11-01,Free and forced wave propagation in beam lattice metamaterials with viscoelastic resonators,"Beam lattice materials are characterized by a periodic microstructure
+realizing a geometrically regular pattern of elementary cells. In these
+microstructured materials, the dispersion properties governing the free dynamic
+propagation of elastic waves can be studied by formulating parametric
+lagrangian models and applying the Floquet-Bloch theory. Within this framework,
+governing the wave propagation by means of spectral design techniques and/or
+energy dissipation mechanisms is a major issue of theoretical and applied
+interest. Specifically, the wave propagation can be inhibited by purposely
+designing the microstructural parameters to open band gaps in the material
+spectrum at target center frequencies. Based on these motivations, a general
+dynamic formulation for determining the dispersion properties of beam lattice
+metamaterials, equipped with local resonators is presented. The mechanism of
+local resonance is realized by tuning periodic auxiliary masses,
+viscoelastically coupled with the beam lattice microstructure. As peculiar
+aspect, the viscoelastic coupling is derived by a mechanical formulation based
+on the Boltzmann superposition integral, whose kernel is approximated by a
+Prony series. Consequently, the free propagation of damped waves is governed by
+a linear homogeneous system of integral-differential equations of motion.
+Therefore, differential equations of motion with frequency-dependent
+coefficients are obtained by applying the bilateral Laplace transform. The
+corresponding complex-valued branches characterizing the dispersion spectrum
+are determined and parametrically analyzed. Particularly, the spectra
+corresponding to Taylor series approximations of the equation coefficients are
+investigated.",1911.00455v1
+2020-11-18,The theory of cosmic-ray scattering on pre-existing MHD modes meets data,"We present a comprehensive study about the phenomenological implications of
+the theory describing Galactic cosmic-ray scattering onto magnetosonic and
+Alfv\'enic fluctuations in the $\mathrm{GeV} - \mathrm{PeV}$ domain. We compute
+a set of diffusion coefficients from first principles, for different values of
+the Alfv\'enic Mach number and other relevant parameters associated to both the
+Galactic halo and the extended disk, taking into account the different damping
+mechanisms of turbulent fluctuations acting in these environments. We confirm
+that the scattering rate associated to Alfv\'enic turbulence is highly
+suppressed if the anisotropy of the cascade is taken into account. On the other
+hand, we highlight that magnetosonic modes play a dominant role in Galactic
+confinement of cosmic rays up to $\mathrm{PeV}$ energies. We implement the
+diffusion coefficients in the numerical framework of the {\tt DRAGON} code, and
+simulate the equilibrium spectrum of different primary and secondary cosmic-ray
+species. We show that, for reasonable choices of the parameters under
+consideration, all primary and secondary fluxes at high energy (above a
+rigidity of $\simeq 200 \, \mathrm{GV}$) are correctly reproduced within our
+framework, in both normalization and slope.",2011.09197v2
+2021-02-03,On Geometric Fourier Particle In Cell Methods,"In this article we describe a unifying framework for variational
+electromagnetic particle schemes of spectral type, and we propose a novel
+spectral Particle-In-Cell (PIC) scheme that preserves a discrete Hamiltonian
+structure. Our work is based on a new abstract variational derivation of
+particle schemes which builds on a de Rham complex where Low's Lagrangian is
+discretized using a particle approximation of the distribution function. In
+this framework, which extends the recent Finite Element based Geometric
+Electromagnetic PIC (GEMPIC) method to a variety of field solvers, the
+discretization of the electromagnetic potentials and fields is represented by a
+de Rham sequence of compatible spaces, and the particle-field coupling
+procedure is described by approximation operators that commute with the
+differential operators in the sequence. In particular, for spectral Maxwell
+solvers the choice of truncated $L^2$ projections using continuous Fourier
+transform coefficients for the commuting approximation operators yields the
+gridless Particle-in-Fourier method, whereas spectral Particle-in-Cell methods
+are obtained by using discrete Fourier transform coefficients computed from a
+grid. By introducing a new sequence of spectral pseudo-differential
+approximation operators, we then obtain a novel variational spectral PIC method
+with discrete Hamiltonian structure that we call Fourier-GEMPIC. Fully discrete
+schemes are then derived using a Hamiltonian splitting procedure, leading to
+explicit time steps that preserve the Gauss laws and the discrete Poisson
+bracket associated with the Hamiltonian structure. These explicit steps share
+many similarities with standard spectral PIC methods. As arbitrary filters are
+allowed in our framework, we also discuss aliasing errors and study a natural
+back-filtering procedure to mitigate the damping caused by anti-aliasing
+smoothing particle shapes.",2102.02106v1
+2021-02-10,Axion Quasiparticles for Axion Dark Matter Detection,"It has been suggested that certain antiferromagnetic topological insulators
+contain axion quasiparticles (AQs), and that such materials could be used to
+detect axion dark matter (DM). The AQ is a longitudinal antiferromagnetic spin
+fluctuation coupled to the electromagnetic Chern-Simons term, which, in the
+presence of an applied magnetic field, leads to mass mixing between the AQ and
+the electric field. The electromagnetic boundary conditions and transmission
+and reflection coefficients are computed. A model for including losses into
+this system is presented, and the resulting linewidth is computed. It is shown
+how transmission spectroscopy can be used to measure the resonant frequencies
+and damping coefficients of the material, and demonstrate conclusively the
+existence of the AQ. The dispersion relation and boundary conditions permit
+resonant conversion of axion DM into THz photons in a material volume that is
+independent of the resonant frequency, which is tuneable via an applied
+magnetic field. A parameter study for axion DM detection is performed,
+computing boost amplitudes and bandwidths using realistic material properties
+including loss. The proposal could allow for detection of axion DM in the mass
+range between 1 and 10 meV using current and near future technology.",2102.05366v2
+2021-05-16,A Realizable Filtered Intrusive Polynomial Moment Method,"Intrusive uncertainty quantification methods for hyperbolic problems exhibit
+spurious oscillations at shocks, which leads to a significant reduction of the
+overall approximation quality. Furthermore, a challenging task is to preserve
+hyperbolicity of the gPC moment system. An intrusive method which guarantees
+hyperbolicity is the intrusive polynomial moment (IPM) method, which performs
+the gPC expansion on the entropy variables. The method, while still being
+subject to oscillations, requires solving a convex optimization problem in
+every spatial cell and every time step. The aim of this work is to mitigate
+oscillations in the IPM solution by applying filters. Filters reduce
+oscillations by damping high order gPC coefficients. Naive filtering, however,
+may lead to unrealizable moments, which means that the IPM optimization problem
+does not have a solution and the method breaks down. In this paper, we propose
+and analyze two separate strategies to guarantee the existence of a solution to
+the IPM problem. First, we propose a filter which maintains realizability by
+being constructed from an underlying Fokker-Planck equation. Second, we
+regularize the IPM optimization problem to be able to cope with non-realizable
+gPC coefficients. Consequently, standard filters can be applied to the
+regularized IPM method. We demonstrate numerical results for the two strategies
+by investigating the Euler equations with uncertain shock structures in one-
+and two-dimensional spatial settings. We are able to show a significant
+reduction of spurious oscillations by the proposed filters.",2105.07473v1
+2021-10-04,Probing three-state Potts nematic fluctuations by ultrasound attenuation,"Motivated by recent studies of three-state Potts nematic states in
+magic-angle twisted bilayer graphene and doped-Bi$_2$Se$_3$, we analyze the
+impact of critical nematic fluctuations on the low energy properties of
+phonons. In this study we propose how to identify the three-state Potts nematic
+fluctuations by ultrasound attenuation. The Gaussian fluctuation analysis shows
+that the Landau damping term becomes isotropic due to fluctuations of the
+$C_{3}$-breaking bond-order, and the nemato-elastic coupling is also shown to
+be isotropic. These two features lead to an isotropic divergence of the
+transverse sound attenuation coefficient and an isotropic lattice softening, in
+contrast to the case of the $C_4$-breaking bond-order which shows the strong
+anisotropy. Moreover, we use a mean-field approximation and discuss the
+impurity effects. The transition temperature takes its maximum near the filling
+of the van-Hove singularity, and the large density of states favors the nematic
+phase transition. It turns out that the phase transition is of weak first-order
+in the wide range of filling and, with increasing the impurity scattering, the
+first order transition line at low temperatures gradually shifts towards the
+second-order line, rendering the transition a weak first-order in a wider range
+of parameters. Furthermore, it is confirmed that the enhancement of the
+ultrasound attenuation coefficient will be clearly observed in experiments in
+the case of a weak first-order phase transition.",2110.01308v4
+2022-11-09,Gravitational wave constraints on spatial covariant gravities,"The direct discovery of gravitational waves (GWs) from the coalescence of
+compact binary components by the LIGO/Virgo/KAGRA Collaboration provides an
+unprecedented opportunity for exploring the underlying theory of gravity that
+drives the coalescence process in the strong and highly dynamical field regime
+of gravity. In this paper, we consider the observational effects of spatial
+covariant gravities on the propagation of GWs in the cosmological background
+and obtain the observational constraints on coupling coefficients in the action
+of spatial covariant gravities from GW observations. We first decompose the GWs
+into the left- and right-hand circular polarization modes and derive the
+effects of the spatial covariant gravities on the propagation equation of GWs.
+We find that these effects can be divided into three classes: 1)
+frequency-independent effects on GW speed and friction, 2) parity-violating
+amplitude and velocity birefringences, and 3) a Lorentz-violating damping rate
+and dispersion of GWs. With these effects, we calculate the corresponding
+modified waveform of GWs generated by the coalescence of compact binaries. By
+comparing these new effects with the publicly available posterior samples or
+results from various tests of gravities with LIGO/Virgo/KAGRA data in the
+literature, we derive the observational constraints on coupling coefficients of
+the spatial covariant gravities. These results represent the most comprehensive
+constraints on the spatial covariant gravities in the literature.",2211.04711v2
+2023-09-08,"Minimum-dissipation model for large-eddy simulation in OpenFoam -A study on channel flow, periodic hills and flow over cylinder","The minimum-dissipation model is applied to turbulent channel flows up to
+$Re_\tau = 2000$, flow past a circular cylinder at $Re=3900$, and flow over
+periodic hills at $Re=10595$. Numerical simulations are performed in OpenFOAM
+which is based on finite volume methods for discretizing partial differential
+equations. We use both symmetry-preserving discretizations and standard
+second-order accurate discretization methods in OpenFOAM on structured meshes.
+The results are compared to DNS and experimental data.
+  The results of channel flow mainly demonstrate the static QR model performs
+equally well as the dynamic models while reducing the computational cost. The
+model constant $C=0.024$ gives the most accurate prediction, and the
+contribution of the sub-grid model decreases with the increase of the mesh
+resolution and becomes very small (less than 0.2 molecular viscosity) if the
+fine meshes are used. Furthermore, the QR model is able to predict the mean and
+rms velocity accurately up to $Re_\tau = 2000$ without a wall damping function.
+The symmetry-preserving discretization outperforms the standard OpenFOAM
+discretization at $Re_\tau=1000$. The results for the flow over a cylinder show
+that mean velocity, drag coefficient, and lift coefficient are in good
+agreement with the experimental data. The symmetry-preserving scheme with the
+QR model predicts the best results. The various comparisons carried out for
+flows over periodic hills demonstrate the need to use the symmetry-preserving
+discretization or central difference schemes in OpenFOAM in combination with
+the minimum dissipation model. The model constant of $C=0.024$ is again the
+best one.",2309.04415v1
+2023-11-02,Minimum-dissipation model for large-eddy simulation using symmetry-preserving discretization in OpenFOAM,"The minimum-dissipation model is applied to channel flow up to $Re_\tau =
+2000$, flow past a circular cylinder at $Re=3900$, and flow over periodic hills
+at $Re=10595$. Numerical simulations were performed in OpenFOAM which is based
+on the finite volume methods. We used both symmetry-preserving and standard
+second-order accurate discretization methods in OpenFOAM on structured meshes.
+The results are compared to DNS and experimental data.
+  The results of channel flow demonstrate a static QR model performs equally
+well as the dynamic models while reducing the computational cost. The model
+constant of $C=0.024$ gives the most accurate prediction, and the contribution
+of the sub-grid model decreases with the increase of the mesh resolution and
+becomes very small (less than 0.2 molecular viscosity) if a fine mesh is used.
+Furthermore, the QR model is able to predict the mean and rms velocity
+accurately up to $Re_\tau = 2000$ without a wall damping function. The
+symmetry-preserving discretization outperforms the standard OpenFOAM
+discretization at $Re_\tau=1000$. The results for the flow over a cylinder show
+that the mean velocity, drag coefficient, and lift coefficient are in good
+agreement with the experimental data and the central difference schemes
+conjugated with the QR model predict better results. The various comparisons
+carried out for flows over periodic hills demonstrate the need to use central
+difference schemes in OpenFOAM in combination with the minimum dissipation
+model. The best model constant is again $C=0.024$. The single wind turbine
+simulation shows that the QR model is capable of predicting accurate results in
+complex rotating scenarios.",2311.01360v1
+2023-11-03,Room-Temperature CsPbBr$_3$ Mixed Polaritons States,"Light-matter interactions are known to lead to the formation of polariton
+states through what is called strong coupling, leading to the formation of two
+hybrid states usually tagged as Upper and Lower Polaritons. Here, we consider a
+similar interaction between excitons and photons in the realm of strong
+interactions, with the difference that it enables us to obtain a
+mixed-polariton state. In this case, the energy of this mixed state is found
+between the energies of the exciton state and the cavity mode, resulting in an
+imaginary coupling coefficient related to a specific class of singular points.
+These mixed states are often considered unobservable, although they are
+predicted well when the dressed states of a two-level atom are considered.
+However, intense light confinement can be obtained by using a Bound State in
+the Continuum, reducing the damping rates, and enabling the observation of
+mixed states resulting from the correct kind of exceptional point giving place
+to strong coupling. In this study, using the Transfer Matrix Method, we
+simulated cavities made of porous silicon coupled with CsPbBr3 perovskite
+quantum dots to numerically observe the mixed states as well as experimentally,
+by fabricating appropriate samples. The dispersion relation of the mixed states
+is fitted using the same equation as that used for strong coupling but
+considering a complex coupling coefficient, which is directly related to the
+appropriate type of exceptional point.",2311.02252v2
+1998-05-22,Analytic description of the r-mode instability in uniform density stars,"We present an analytic description of the $r$-mode instability in newly-born
+neutron stars, using the approximation of uniform density. Our computation is
+consistently accurate to second order in the angular velocity of the star. We
+obtain formulae for the growth-time of the instability due to
+gravitational-wave emission, for both current and mass multipole radiation and
+for the damping timescale, due to viscosity. The $l=m=2$ current-multipole
+radiation dominates the timescale of the instability. We estimate the deviation
+of the second order accurate results from the lowest order approximation and
+show that the uncertainty in the equation of state has only a small effect on
+the onset of the $r$-mode instability. The viscosity coefficients and the
+cooling process in newly-born neutron stars are, at present, uncertain and our
+analytic formaulae enables a quick check of such effects on the development of
+the instability.",9805297v1
+2004-06-21,Resolution and accuracy of resonances in R-matrix cross sections,"We investigate the effect of resonances in photoionization and recombination
+cross sections computed using the R-matrix method. Photoionization and
+recombination rates derived from high-resolution cross sections for oxygen ions
+are compared with earlier works with less resolution and accuracy, such as in
+the widely used Opacity Project data. We find significant differences in
+photoionization rates for O II metastable states, averaged over Planck
+functions corresponding to ionizing radiation fields, with respect to the
+intrinsic accuracy of the calculations and improved resolution. Furthermore,
+for highly charged ions other physical effects are also important.
+Recombination rate coefficients, averaged over a Maxwellian distribution, are
+extremely sensitive to the position and resolution of near-threshold
+resonances, and radiation damping, in (e + O VII) --> O VI + hnu. Surprisingly
+however, the effect on the monochromatic and the mean Rosseland and Planck
+bound-free opacities is relatively small, but may be potentially significant.",0406472v1
+2006-07-01,Exotic bulk viscosity and its influence on neutron star r-modes,"We investigate the effect of exotic matter in particular, hyperon matter on
+neutron star properties such as equation of state (EoS), mass-radius
+relationship and bulk viscosity. Here we construct equations of state within
+the framework of a relativistic field theoretical model. As hyperons are
+produced abundantly in dense matter, hyperon-hyperon interaction becomes
+important and is included in this model. Hyperon-hyperon interaction gives rise
+to a softer EoS which results in a smaller maximum mass neutron star compared
+with the case without the interaction. Next we compute the coefficient of bulk
+viscosity and the corresponding damping time scale due to the non-leptonic weak
+process including $\Lambda$ hyperons. Further, we investigate the role of the
+bulk viscosity on gravitational radiation driven r-mode instability in a
+neutron star of given mass and temperature and find that the instability is
+effectively suppressed.",0607005v2
+2006-07-11,Collisional Particle Disks,"We present a new, simple, fast algorithm to numerically evolve disks of
+inelastically colliding particles surrounding a central star. Our algorithm
+adds negligible computational cost to the fastest existing collisionless N-body
+codes, and can be used to simulate, for the first time, the interaction of
+planets with disks over many viscous times. Though the algorithm is implemented
+in two dimensions-i.e., the motions of bodies need only be tracked in a
+plane-it captures the behavior of fully three-dimensional disks in which
+collisions maintain inclinations that are comparable to random eccentricities.
+We subject the algorithm to a battery of tests for the case of an isolated,
+narrow, circular ring. Numerical simulations agree with analytic theory with
+regards to how particles' random velocities equilibrate; how the ring viscously
+spreads; and how energy dissipation, angular momentum transport, and material
+transport are connected. We derive and measure the critical value of the
+coefficient of restitution above which viscous stirring dominates inelastic
+damping and the particles' velocity dispersion runs away.",0607241v1
+2007-01-19,Revised Primordial Helium Abundance Based on New Atomic Data,"We have derived a primordial helium abundance of Yp = 0.2477 +- 0.0029, based
+on new atomic physics computations of the recombination coefficients of He I
+and of the collisional excitation of the H I Balmer lines together with
+observations and photoionization models of metal-poor extragalactic H II
+regions. The new atomic data increase our previous determination of Yp by
+0.0086, a very significant amount. By combining our Yp result with the
+predictions made by the standard Big Bang nucleosynthesis model, we find a
+baryon-to-photon ratio, \eta, in excellent agreement both with the \eta value
+derived by the primordial deuterium abundance value observed in damped
+Lyman-\alpha systems and with the one obtained from the WMAP observations.",0701580v2
+1995-07-03,Fundamental steps of group velocity for slow surface polariton under the quantum hall effect conditions,"A new type of collective electromagnetic excitations, namely surface
+polaritons (SP) --- in a 2D electronic layer in a high magnetic field under
+Quantum Hall Effect (QHE) conditions is predicted. We have found the spectrum,
+damping, and polarization of the SP in a wide range of frequencies $\omega$ and
+wavevectors $\bf k$. It is shown that near the Cyclotron Resonance (CR)
+($\omega\sim\Omega=\displaystyle eB/mc$) the phase velocity of the SP is
+drastically slowed down and the group velocity undergoes fundamental steps
+defined by the Fine Structure Constant $\alpha=e^2/\hbar c$. In the vicinity of
+a CR subharmonic ($\omega\sim 2 \Omega$) the negative (anomalous) dispersion of
+the SP occurs. The relaxation of electrons in the 2D layer gives rise to a new
+dissipative collective threshold-type mode of the SP. We suggest a method for
+calculating the kinetic coefficients for the 2D electronic layer under QHE
+condition, using the Wigner distribution function formalism and determine their
+spatial and frequency dispersion. Using this method we have calculated the
+line-shape of the CR and the d.c. conductance under the QHE condition, which
+are in good agreement with experimental data.",9507001v1
+1996-04-26,Macroscopic Quantum Tunneling of a Fluxon in a Long Josephson Junction,"Macroscopic quantum tunneling (MQT) for a single fluxon moving along a long
+Josephson junction is studied theoretically. To introduce a fluxon-pinning
+force, we consider inhomogeneities made by modifying thickness of an insulating
+layer locally. Two different situations are studied: one is the quantum
+tunneling from a metastable state caused by a single inhomogeneity, and the
+other is the quantum tunneling in a two-state system made by two
+inhomogeneities. In the quantum tunneling from a metastable state, the decay
+rate is estimated within the WKB approximation. Dissipation effects on a fluxon
+dynamics are taken into account by the Caldeira-Leggett theory. We propose a
+device to observe quantum tunneling of a fluxon experimentally. Required
+experimental resolutions to observe MQT of a fluxon seem attainable within the
+presently available micro-fabrication technique. For the two-state system, we
+study quantum resonance between two stable states, i.e., macroscopic quantum
+coherence (MQC). From the estimate for dissipation coefficients due to
+quasiparticle tunneling, the observation of MQC appears to be possible within
+the Caldeira-Leggett theory.",9604160v2
+1997-09-03,Shaping an ultracold atomic soliton in a travelling wave laser beam,"An ultracold wave packet of bosonic atoms loaded into a travelling laser wave
+may form a many-atom soliton.This is disturbed by a homogeneous force field,
+for example by the inevitable gravitation. The wave packet is accelerated and
+therefore the laser frequency appears to be chirped in the rest frame of the
+atoms. We derive the effective nonlinear Schr\""odinger equation. It shows a
+time dependent nonlinearity coefficient which amounts to a damping or
+antidamping, respectively. The accelerated packet solution remains a soliton
+which changes its shape adiabatically. Similarly, an active shaping can be
+obtained in the force-free case by chirping the laser frequency thus
+representing a way of coherent control of the soliton form. The experimental
+consequences are discussed.",9709038v1
+1997-10-20,Row-switched states in two-dimensional underdamped Josephson junction arrays,"When magnetic flux moves across layered or granular superconductor
+structures, the passage of vortices can take place along channels which develop
+finite voltage, while the rest of the material remains in the zero-voltage
+state. We present analytical studies of an example of such mixed dynamics: the
+row-switched (RS) states in underdamped two-dimensional Josephson arrays,
+driven by a uniform DC current under external magnetic field but neglecting
+self-fields. The governing equations are cast into a compact
+differential-algebraic system which describes the dynamics of an assembly of
+Josephson oscillators coupled through the mesh current. We carry out a formal
+perturbation expansion, and obtain the DC and AC spatial distributions of the
+junction phases and induced circulating currents. We also estimate the interval
+of the driving current in which a given RS state is stable. All these
+analytical predictions compare well with our numerics. We then combine these
+results to deduce the parameter region (in the damping coefficient versus
+magnetic field plane) where RS states can exist.",9710204v1
+1998-04-21,Inelastic collapse of a randomly forced particle,"We consider a randomly forced particle moving in a finite region, which
+rebounds inelastically with coefficient of restitution r on collision with the
+boundaries. We show that there is a transition at a critical value of r,
+r_c\equiv e^{-\pi/\sqrt{3}}, above which the dynamics is ergodic but beneath
+which the particle undergoes inelastic collapse, coming to rest after an
+infinite number of collisions in a finite time. The value of r_c is argued to
+be independent of the size of the region or the presence of a viscous damping
+term in the equation of motion.",9804229v1
+1999-02-25,Mobility of Bloch Walls via the Collective Coordinate Method,"We have studied the problem of the dissipative motion of Bloch walls
+considering a totally anisotropic one dimensional spin chain in the presence of
+a magnetic field. Using the so-called ""collective coordinate method"" we
+construct an effective Hamiltonian for the Bloch wall coupled to the magnetic
+excitations of the system. It allows us to analyze the Brownian motion of the
+wall in terms of the reflection coefficient of the effective potential felt by
+the excitations due to the existence of the wall. We find that for finite
+values of the external field the wall mobility is also finite. The spectrum of
+the potential at large fields is investigated and the dependence of the damping
+constant on temperature is evaluated. As a result we find the temperature and
+magnetic field dependence of the wall mobility.",9902330v1
+2004-02-21,Effect of backing thickness on determination of the phase in neutron reflectometry by variation of backing,"The determination of density profiles with knowing the phase information of
+complex reflection coefficient for neutron specularly reflected from a film,
+yields unique results. Recently it has been shown that the phase can be
+determined by using controlled variation of the scattering length density of
+the fronting (incident) and/or backing (substrate) medium instead of reference
+layers of finite thickness. This method is applicable under the simplifying
+assumption that the backing is infinitely thick (semi-infinite substrate). By
+this assumption the reflected beams from the end side of the backing is
+neglected, which appears reasonable since in most cases absorption will damp
+out the neutron current before it has reached the end side. But for weakly
+absorbing backing, the reflection from the end side may be considerable. So
+backing must be considered as a thick matter. We show that for this kind of
+backing, using method of variation of the backing, as an example of variation
+of the surroundings, leads to completely wrong answer in determination of the
+phase.",0402541v1
+2004-03-23,Phase transitions induced by noise cross-correlations,"A general approach to consider spatially extended stochastic systems with
+correlations between additive and multiplicative noises subject to nonlinear
+damping is developed. Within modified cumulant expansion method, we derive an
+effective Fokker-Planck equation whose stationary solutions describe a
+character of ordered state. We find that fluctuation cross-correlations lead to
+a symmetry breaking of the distribution function even in the case of the
+zero-dimensional system. In general case, continuous, discontinuous and
+reentrant noise induced phase transitions take place. It is appeared the
+cross-correlations play a role of bias field which can induce a chain of phase
+transitions being different in nature. Within mean field approach, we give an
+intuitive explanation of the system behavior through an effective potential of
+thermodynamic type. This potential is written in the form of an expansion with
+coefficients defined by temperature, intensity of spatial coupling, auto- and
+cross-correlation times and intensities of both additive and multiplicative
+noises.",0403583v2
+2004-12-13,Field-tuned quantum critical point of antiferromagnetic metals,"A magnetic field applied to a three-dimensional antiferromagnetic metal can
+destroy the long-range order and thereby induce a quantum critical point. Such
+field-induced quantum critical behavior is the focus of many recent
+experiments. We investigate theoretically the quantum critical behavior of
+clean antiferromagnetic metals subject to a static, spatially uniform external
+magnetic field. The external field does not only suppress (or induce in some
+systems) antiferromagnetism but also influences the dynamics of the order
+parameter by inducing spin precession. This leads to an exactly marginal
+correction to spin-fluctuation theory. We investigate how the interplay of
+precession and damping determines the specific heat, magnetization,
+magnetocaloric effect, susceptibility and scattering rates. We point out that
+the precession can change the sign of the leading \sqrt{T} correction to the
+specific heat coefficient c(T)/T and can induce a characteristic maximum in
+c(T)/T for certain parameters. We argue that the susceptibility \chi =\partial
+M/\partial B is the thermodynamic quantity which shows the most significant
+change upon approaching the quantum critical point and which gives experimental
+access to the (dangerously irrelevant) spin-spin interactions.",0412284v1
+2005-10-13,Statistical-mechanical description of classical test-particle dynamics in the presence of an external force field: modelling noise and damping from first principles,"Aiming to establish a rigorous link between macroscopic random motion
+(described e.g. by Langevin-type theories) and microscopic dynamics, we have
+undertaken a kinetic-theoretical study of the dynamics of a classical
+test-particle weakly coupled to a large heat-bath in thermal equilibrium. Both
+subsystems are subject to an external force field. From the (time-non-local)
+generalized master equation a Fokker-Planck-type equation follows as a
+""quasi-Markovian"" approximation. The kinetic operator thus defined is shown to
+be ill-defined; in specific, it does not preserve the positivity of the
+test-particle distribution function $f(\mathbf{x}, \mathbf{v}; t)$. Adopting an
+alternative approach, previously proposed for quantum open systems, is proposed
+to lead to a correct kinetic operator, which yields all the expected
+properties. A set of explicit expressions for the diffusion and drift
+coefficients are obtained, allowing for modelling macroscopic diffusion and
+dynamical friction phenomena, in terms of an external field and intrinsic
+physical parameters.",0510359v2
+2006-04-13,Dissipative magneto-optic solitons,"Magneto-optic behaviour is a specific, non-reciprocal example of gyrotropic
+behaviour. When coupled to photo-induced Faraday rotation it is possible to
+discriminate this effect from the background of other nonlinear effects
+Non-reciprocal behaviour is characteristic of artificial gyrotropy and can be
+used in optical isolators and a range of coherence and quantum problems. This
+is all in sharp contrast to natural gyrotropy, like optical activity. it is
+also important to go beyond third-order, Kerr, optical nonlinearity and move
+towards a saturable model of terms in the polarisation. In this spirit, this
+chapter seeks to determinate the influence of a magneto-optic presence upon an
+optically nonlinear material that is modelled by a cubic-quintic form of
+polarisation. In addition, the coefficients of the envelope equation will be
+made complex, to take into account both linear and nonlinear damping and cubic
+gain processes. The emphasis is upon the simulation outcomes, however, rather
+the applications.",0604355v1
+2006-12-07,Dynamics of a metastable state nonlinearly coupled to a heat bath driven by an external noise,"Based on a system-reservoir model, where the system is nonlinearly coupled to
+a heat bath and the heat bath is modulated by an external stationary Gaussian
+noise, we derive the generalized Langevin equation with space dependent
+friction and multiplicative noise and construct the corresponding Fokker-Planck
+equation, valid for short correlation time, with space dependent diffusion
+coefficient to study the escape rate from a metastable state in the moderate to
+large damping regime. By considering the dynamics in a model cubic potential we
+analyze the result numerically which are in good agreement with the theoretical
+prediction. It has been shown numerically that the enhancement of rate is
+possible by properly tuning the correlation time of the external noise.",0612193v2
+2002-12-03,d-Dimensional Black Hole Entropy Spectrum from Quasi-Normal Modes,"Starting from recent observations\cite{hod,dreyer1} about quasi-normal modes,
+we use semi-classical arguments to derive the Bekenstein-Hawking entropy
+spectrum for $d$-dimensional spherically symmetric black holes. We find that
+the entropy spectrum is equally spaced: $S_{BH}=k \ln(m_0)n$, where $m_0$ is a
+fixed integer that must be derived from the microscopic theory. As shown in
+\cite{dreyer1},4-$d$ loop quantum gravity yields precisely such a spectrum with
+$m_0=3$ providing the Immirzi parameter is chosen appropriately. For
+$d$-dimensional black holes of radius $R_H(M)$, our analysis requires the
+existence of a unique quasinormal mode frequency in the large damping limit
+$\omega^{(d)}(M) = \alpha^{(d)}c/ R_H(M)$ with coefficient $\alpha^{(d)} =
+{(d-3)/over 4\pi} \ln(m_0)$, where $m_0$ is an integer and $\Gamma^{(d-2)}$ is
+the volume of the unit $d-2$ sphere.",0212014v2
+2003-12-17,A Post-Newtonian diagnostic of quasi-equilibrium binary configurations of compact objects,"Using equations of motion accurate to the third post-Newtonian (3PN) order
+(O(v/c)^6 beyond Newtonian gravity), we derive expressions for the total energy
+E and angular momentum J of the orbits of compact binary systems (black holes
+or neutron stars) for arbitrary orbital eccentricity. We also incorporate
+finite-size contributions such as spin-orbit and spin-spin coupling, and
+rotational and tidal distortions, calculated to the lowest order of
+approximation, but we exclude the effects of gravitational radiation damping.
+We describe how these formulae may be used as an accurate diagnostic of the
+physical content of quasi-equilibrium configurations of compact binary systems
+of black holes and neutron stars generated using numerical relativity. As an
+example, we show that quasi-equilibrium configurations of corotating neutron
+stars recently reported by Miller et al. can be fit by our diagnostic to better
+than one per cent with a circular orbit and with physically reasonable tidal
+coefficients.",0312082v3
+1994-07-29,Standard Model Baryogenesis,"Simply on CP arguments, we argue against a Standard Model explanation of
+baryogenesis via the charge transport mechanism. A CP-asymmetry is found in the
+reflection coefficients of quarks hitting the electroweak phase boundary
+created during a first order phase transition. The problem is analyzed both in
+an academic zero temperature case and in the realistic finite temperature one.
+At finite temperature, a crucial role is played by the damping rate of
+quasi-quarks in a hot plasma, which induces loss of spatial coherence and
+suppresses reflection on the boundary even at tree-level. The resulting baryon
+asymmetry is many orders of magnitude below what observation requires. We
+comment as well on related works.",9407403v2
+2000-02-25,A New Source for Electroweak Baryogenesis in the MSSM,"One of the most experimentally testable explanations for the origin of the
+baryon asymmetry of the universe is that it was created during the electroweak
+phase transition, in the minimal supersymmetric standard model. Previous
+efforts have focused on the current for the difference of the two Higgsino
+fields, $H_1-H_2$, as the source of biasing sphalerons to create the baryon
+asymmetry. We point out that the current for the orthogonal linear combination,
+$H_1+H_2$, is larger by several orders of magnitude. Although this increases
+the efficiency of electroweak baryogenesis, we nevertheless find that large
+CP-violating angles $\ge 0.15$ are required to get a large enough baryon
+asymmetry.",0002272v2
+2000-06-15,Development of the electroweak phase transition and baryogenesis,"We investigate the evolution of the electroweak phase transition, using a
+one-Higgs effective potential that can be regarded as an approximation for the
+Minimal Supersymmetric Standard Model. The phase transition occurs in a small
+interval around a temperature T_t below the critical one. We calculate this
+temperature as a function of the parameters of the potential and of a damping
+coefficient related to the viscosity of the plasma. The parameters that are
+relevant for baryogenesis, such as the velocity and thickness of the walls of
+bubbles and the value of the Higgs field inside them, change significantly in
+the range of temperatures where the first-order phase transition can occur.
+However, we find that in the likely interval for T_t there is no significant
+variation of these parameters. Furthermore, the temperature T_t is in general
+not far below the temperature at which bubbles begin to nucleate.",0006177v2
+2001-03-09,Transport theory for a two-flavor color superconductor,"QCD with two light quark flavors at high baryonic density and low temperature
+is a color superconductor. The diquark condensate partially breaks the SU(3)
+gauge symmetry down to an SU(2) subgroup. We study thermal fluctuations of the
+superconductor for temperatures below the gap. These are described by a simple
+transport equation, linked to a quasiparticle behavior of the thermal
+excitations of the condensate. When solved in the collisionless limit and close
+to equilibrium, it gives rise to the ``hard superconducting loop'' (HSL)
+effective theory for the unbroken SU(2) gauge fields with momenta smaller than
+the gap. This theory describes Debye screening and Landau damping of the gauge
+fields in the presence of the diquark condensate. We also explain how our
+effective theory follows to one-loop order from quantum field theory. Our
+approach provides a convenient starting point for the computation of transport
+coefficients of the two-flavor color superconductor.",0103092v2
+2002-05-18,Perturbative and non-perturbative aspects of the non-abelian Boltzmann-Langevin equation,"We study the Boltzmann-Langevin equation which describes the dynamics of hot
+Yang-Mills fields with typical momenta of order of the magnetic screening scale
+g^2 T. It is transformed into a path integral and Feynman rules are obtained.
+We find that the leading log Langevin equation can be systematically improved
+in a well behaved expansion in log(1/g)^-1. The result by Arnold and Yaffe that
+the leading log Langevin equation is still valid at next-to-leading-log order
+is confirmed. We also confirm their result for the next-to-leading-log damping
+coefficient, or color conductivity, which is shown to be gauge fixing
+independent for a certain class of gauges. The frequency scale g^2T does not
+contribute to this result, but it does contribute, by power counting, to the
+transverse gauge field propagator. Going beyond a perturbative expansion we
+find 1-loop ultraviolet divergences which cannot be removed by renormalizing
+the parameters in the Boltzmann-Langevin equation.",0205202v2
+2003-07-05,"Hard Loops, Soft Loops, and High Density Effective Field Theory","We study several issues related to the use of effective field theories in QCD
+at large baryon density. We show that the power counting is complicated by the
+appearance of two scales inside loop integrals. Hard dense loops involve the
+large scale $\mu^2$ and lead to phenomena such as screening and damping at the
+scale $g\mu$. Soft loops only involve small scales and lead to superfluidity
+and non-Fermi liquid behavior at exponentially small scales. Four-fermion
+operators in the effective theory are suppressed by powers of $1/\mu$, but they
+get enhanced by hard loops. As a consequence their contribution to the pairing
+gap is only suppressed by powers of the coupling constant, and not powers of
+$1/\mu$. We determine the coefficients of four-fermion operators in the
+effective theory by matching quark-quark scattering amplitudes. Finally, we
+introduce a perturbative scheme for computing corrections to the gap parameter
+in the superfluid phase",0307074v1
+2004-02-04,Infrared Behavior of High-Temperature QCD,"The damping rate \gamma_t(p) of on-shell transverse gluons with ultrasoft
+momentum p is calculated in the context of next-to-leading-order
+hard-thermal-loop-summed perturbation of high-temperature QCD. It is obtained
+in an expansion to second order in p. The first coefficient is recovered but
+that of order p^2 is found divergent in the infrared. Divergences from
+light-like momenta do also occur but are circumvented. Our result and method
+are critically discussed, particularly regarding a Ward identity obtained in
+the literature. When enforcing the equality between \gamma_t(0) and
+\gamma_l(0), a rough estimate of the magnetic mass is obtained. Carrying a
+similar calculation in the context of scalar quantum electrodynamics shows that
+the early ultrasoft-momentum expansion we make has little to do with the
+infrared sensitivity of the result.",0402041v1
+2004-06-04,Shear Viscosity in a CFL Quark Star,"We compute the mean free path and shear viscosity in the color-flavor locked
+(CFL) phase of dense quark matter at low temperature T, when the contributions
+of mesons, quarks and gluons to the transport coefficients are Boltzmann
+suppressed. CFL quark matter displays superfluid properties, and transport
+phenomena in such cold regime are dominated by phonon-phonon scattering. We
+study superfluid phonons within thermal field theory and compute the mean free
+path associated to their most relevant collision processes. Small-angle
+processes turn out to be more efficient in slowing transport phenomena in the
+CFL matter, while the mean free path relevant for the shear viscosity is less
+sensitive to collinear scattering due to the presence of zero modes in the
+Boltzmann equation. In analogy with superfluid He4, we find the same T power
+law for the superfluid phonon damping rate and mean free path. Our results are
+relevant for the study of rotational properties of compact stars, and correct
+wrong estimates existing in the literature.",0406058v3
+2005-01-11,Fermionic dispersion relations in ultradegenerate relativistic plasmas beyond leading logarithmic order,"We determine the dispersion relations of fermionic quasiparticles in
+ultradegenerate plasmas by a complete evaluation of the on-shell
+hard-dense-loop-resummed one-loop fermion self energy for momenta of the order
+of the Fermi momentum and above. In the case of zero temperature, we calculate
+the nonanalytic terms in the vicinity of the Fermi surface beyond the known
+logarithmic approximation, which turn out to involve fractional higher powers
+in the energy variable. For nonzero temperature (but much smaller than the
+chemical potential), we obtain the analogous expansion in closed form, which is
+then analytic but involves polylogarithms. These expansions are compared with a
+full numerical evaluation of the resulting group velocities and damping
+coefficients.",0501089v2
+1994-07-19,On the Macroscopic Limit of Nuclear Dissipation,"The Landau-Vlasov equation is applied to a slab of width $L$. This geometry
+is introduced to simulate somehow the finiteness of real nuclei but to allow
+for analytical solutions, nevertheless. We focus on the damping of low
+frequency surface modes and discuss their friction coefficient. For this
+quantity we study the macroscopic limit as defined by $L\to \infty$. We
+demonstrate that the same result can be obtained for finite $L$ by applying an
+appropriate frequency smoothing, if only the smearing interval is sufficiently
+large. The apparent, but important consequences are discussed which this result
+will have for the understanding of the nature of dissipation in real nuclei.",9407029v1
+1997-12-08,Amplitude equations and pattern selection in Faraday waves,"A nonlinear theory of pattern selection in parametric surface waves (Faraday
+waves) is presented that is not restricted to small viscous dissipation. By
+using a multiple scale asymptotic expansion near threshold, a standing wave
+amplitude equation is derived from the governing equations. The amplitude
+equation is of gradient form, and the coefficients of the associated Lyapunov
+function are computed for regular patterns of various symmetries as a function
+of a viscous damping parameter gamma. For gamma approximately 1, the selected
+wave pattern comprises a single standing wave (stripe pattern). For gamma much
+less than 1, patterns of square symmetry are obtained in the capillary regime
+(large frequencies). At lower frequencies (the mixed gravity-capillary regime),
+a sequence of six-fold (hexagonal), eight-fold,... patterns are predicted. For
+even lower frequencies (gravity waves) a stripe pattern is again selected. Our
+predictions of the stability regions of the various patterns are in
+quantitative agreement with recent experiments conducted in large aspect ratio
+systems.",9712003v1
+2003-04-17,Linear theory of nonlocal transport in a magnetized plasma,"A system of nonlocal electron-transport equations for small perturbations in
+a magnetized plasma is derived using the systematic closure procedure of V. Yu.
+Bychenkov et al., Phys. Rev. Lett. 75, 4405 (1995). Solution to the linearized
+kinetic equation with a Landau collision operator is obtained in the diffusive
+approximation. The Fourier components of the longitudinal, oblique, and
+transversal electron fluxes are found in an explicit form for quasistatic
+conditions in terms of the generalized forces: the gradients of density and
+temperature, and the electric field. The full set of nonlocal transport
+coefficients is given and discussed. Nonlocality of transport enhances electron
+fluxes across magnetic field above the values given by strongly collisional
+local theory. Dispersion and damping of magnetohydrodynamic waves in weakly
+collisional plasmas is discussed. Nonlocal transport theory is applied to the
+problem of temperature relaxation across the magnetic field in a laser hot
+spot.",0304063v1
+2005-10-20,"Probing liquid surface waves, liquid properties and liquid films with light diffraction","Surface waves on liquids act as a dynamical phase grating for incident light.
+In this article, we revisit the classical method of probing such waves
+(wavelengths of the order of mm) as well as inherent properties of liquids and
+liquid films on liquids, using optical diffraction. A combination of simulation
+and experiment is proposed to trace out the surface wave profiles in various
+situations (\emph{eg.} for one or more vertical, slightly immersed,
+electrically driven exciters). Subsequently, the surface tension and the
+spatial damping coefficient (related to viscosity) of a variety of liquids are
+measured carefully in order to gauge the efficiency of measuring liquid
+properties using this optical probe. The final set of results deal with liquid
+films where dispersion relations, surface and interface modes, interfacial
+tension and related issues are investigated in some detail, both theoretically
+and experimentally. On the whole, our observations and analyses seem to support
+the claim that this simple, low--cost apparatus is capable of providing a
+wealth of information on liquids and liquid surface waves in a non--destructive
+way.",0510184v2
+2002-04-30,Laser-driven atom moving in a multimode cavity: strong enhancement of cavity-cooling efficiency,"Cavity-mediated cooling of the center--of--mass motion of a transversally,
+coherently pumped atom along the axis of a high--Q cavity is studied. The
+internal dynamics of the atomic dipole strongly coupled to the cavity field is
+treated by a non-perturbative quantum mechanical model, while the effect of the
+cavity on the external motion is described classically in terms of the
+analytically obtained linear friction and diffusion coefficients. Efficient
+cavity-induced damping is found which leads to steady-state temperatures
+well-below the Doppler limit. We reveal a mathematical symmetry between the
+results here and for a similar system where, instead of the atom, the cavity
+field is pumped. The cooling process is strongly enhanced in a degenerate
+multimode cavity. Both the temperature and the number of scattered photons
+during the characteristic cooling time exhibits a significant reduction with
+increasing number of modes involved in the dynamics. The residual number of
+spontaneous emissions in a cooling time for large mode degeneracy can reach and
+even drop below the limit of a single photon.",0204170v1
+2004-07-06,Field quantization in inhomogeneous absorptive dielectrics,"The quantization of the electromagnetic field in a three-dimensional
+inhomogeneous dielectric medium with losses is carried out in the framework of
+a damped-polariton model with an arbitrary spatial dependence of its
+parameters. The equations of motion for the canonical variables are solved
+explicitly by means of Laplace transformations for both positive and negative
+time. The dielectric susceptibility and the quantum noise-current density are
+identified in terms of the dynamical variables and parameters of the model. The
+operators that diagonalize the Hamiltonian are found as linear combinations of
+the canonical variables, with coefficients depending on the electric
+susceptibility and the dielectric Green function. The complete time dependence
+of the electromagnetic field and of the dielectric polarization is determined.
+Our results provide a microscopic justification of the phenomenological
+quantization scheme for the electromagnetic field in inhomogeneous dielectrics.",0407045v1
+2006-09-15,Photoionization Broadening of the 1S-2S Transition in a Beam of Atomic Hydrogen,"We consider the excitation dynamics of the two-photon \sts transition in a
+beam of atomic hydrogen by 243 nm laser radiation. Specifically, we study the
+impact of ionization damping on the transition line shape, caused by the
+possibility of ionization of the 2S level by the same laser field. Using a
+Monte-Carlo simulation, we calculate the line shape of the \sts transition for
+the experimental geometry used in the two latest absolute frequency
+measurements (M. Niering {\it et al.}, PRL 84, 5496 (2000) and M. Fischer {\it
+et al.}, PRL 92, 230802 (2004)). The calculated line shift and line width are
+in excellent agreement with the experimentally observed values. From this
+comparison we can verify the values of the dynamic Stark shift coefficient for
+the \sts transition for the first time on a level of 15%. We show that the
+ionization modifies the velocity distribution of the metastable atoms, the line
+shape of the \sts transition, and has an influence on the derivation of its
+absolute frequency.",0609114v1
+2006-09-21,ε-convertibility of entangled states and extension of Schmidt rank in infinite-dimensional systems,"By introducing the concept of $\epsilon$-convertibility, we extend Nielsen's
+and Vidal's theorems to the entanglement transformation of infinite-dimensional
+systems. Using an infinite-dimensional version of Vidal's theorem we derive a
+new stochastic-LOCC (SLOCC) monotone which can be considered as an extension of
+the Schmidt rank. We show that states with polynomially-damped Schmidt
+coefficients belong to a higher rank of entanglement class in terms of SLOCC
+convertibility. For the case of Hilbert spaces of countable, but infinite
+dimensionality, we show that there are actually an uncountable number of
+classes of pure non-interconvertible bipartite entangled states.",0609167v4
+2007-04-20,Determining factors behind the PageRank log-log plot,"We study the relation between PageRank and other parameters of information
+networks such as in-degree, out-degree, and the fraction of dangling nodes. We
+model this relation through a stochastic equation inspired by the original
+definition of PageRank. Further, we use the theory of regular variation to
+prove that PageRank and in-degree follow power laws with the same exponent. The
+difference between these two power laws is in a multiple coefficient, which
+depends mainly on the fraction of dangling nodes, average in-degree, the power
+law exponent, and damping factor. The out-degree distribution has a minor
+effect, which we explicitly quantify. Our theoretical predictions show a good
+agreement with experimental data on three different samples of the Web.",0704.2694v1
+2007-05-15,Electrical excitation of shock and soliton-like waves in two-dimensional electron channels,"We study electrical excitation of nonlinear plasma waves in heterostructures
+with two-dimensional electron channels and with split gates, and the
+propagation of these waves using hydrodynamic equations for electron transport
+coupled with two-dimensional Poisson equation for self-consistent electric
+potential. The term related to electron collisions with impurities and phonons
+as well as the term associated with viscosity are included into the
+hydrodynamic equations. We demonstrate the formation of shock and soliton-like
+waves as a result of the evolution of strongly nonuniform initial electron
+density distribution. It is shown that the shock wave front and the shape of
+soliton-like pulses pronouncedly depend on the coefficient of viscosity, the
+thickness of the gate layer and the nonuniformity of the donor distribution
+along the channel. The electron collisions result in damping of the shock and
+soliton-like waves, while they do not markedly affect the thickness of the
+shock wave front.",0705.2111v1
+2007-07-27,Oscillatory D'yakonov-Perel' spin dynamics in two dimensional electron gases,"Optical pump-probe measurements of spin-dynamics at temperatures down to 1.5K
+are described for a series of (001)-oriented GaAs/AlGaAs quantum well samples
+containing high mobility two-dimensional electron gases (2DEGs). For well
+widths ranging from 5 nm to 20 nm and 2DEG sheet densities from 1.75x1011cm-2
+to 3.5x1011cm-2 the evolution of a small injected spin population is found to
+be a damped oscillation rather than exponential relaxation, consistent with the
+quasi-collision-free regime of D'yakonov-Perel spin dynamics. A Monte Carlo
+simulation method is used to extract the spin-orbit-induced electron spin
+precession frequency |W(kF)| and electron momentum scattering time tp* at the
+Fermi wavevector. The spin decay time passes through a minimum at a temperature
+corresponding to the transition from collision-free to collision-dominated
+regimes and tp* is found to be close to the ensemble momentum scattering time
+tp obtained from Hall measurements of electron mobility. The values of |W(kF)|
+give the Dresselhaus (BIA) coefficient of spin-orbit interaction as a function
+of electron confinement energy in the quantum show, qualitatively, the
+behaviour expected from k.p theory.",0707.4180v1
+2008-01-07,Field Theoretic Description of Ultrarelativistic Electron-Positron Plasmas,"Ultrarelativistic electron-positron plasmas can be produced in high-intensity
+laser fields and play a role in various astrophysical situations. Their
+properties can be calculated using QED at finite temperature. Here we will use
+perturbative QED at finite temperature for calculating various important
+properties, such as the equation of state, dispersion relations of collective
+plasma modes of photons and electrons, Debye screening, damping rates, mean
+free paths, collision times, transport coefficients, and particle production
+rates, of ultrarelativistic electron-positron plasmas. In particular, we will
+focus on electron-positron plasmas produced with ultra-strong lasers.",0801.0956v2
+2008-05-20,Probability of metastable configurations in spherical three-dimensional Yukawa crystals,"Recently the occurrence probabilities of ground- and metastable states of
+three-dimensional Yukawa clusters with 27 and 31 particles have been analyzed
+in dusty plasma experiments [Block et al., Physics of Plasmas 15, 040701
+(2008)]. There it was found that, in many cases, the ground state appeared
+substantially less frequently than excited states. Here we analyze this
+question theoretically by means of molecular dynamics (MD) and Monte Carlo
+simulations and an analytical method based on the canonical partition function.
+We confirm that metastable states can occur with a significantly higher
+probability than the ground state. The results strongly depend on the screening
+parameter of the Yukawa interaction and the damping coefficient used in the MD
+simulations. The analytical method allows one to gain insight into the
+mechanisms being responsible for the occurrence probabilities of metastable
+states in strongly correlated finite systems.",0805.3016v1
+2008-05-29,Dispersion enhancement and damping by buoyancy driven flows in 2D networks of capillaries,"The influence of a small relative density difference on the displacement of
+two miscible liquids is studied experimentally in transparent 2D networks of
+micro channels. Both stable displacements in which the denser fluid enters at
+the bottom of the cell and displaces the lighter one and unstable displacements
+in which the lighter fluid is injected at the bottom and displaces the denser
+one are realized. Except at the lowest mean flow velocity U, the average
+$C(x,t)$ of the relative concentration satisfies a convection-dispersion
+equation. The dispersion coefficient is studied as function of the relative
+magnitude of fluid velocity and of the velocity of buoyancy driven fluid
+motion. A model is suggested and its applicability to previous results obtained
+in 3D media is discussed.",0805.4564v1
+2008-06-12,Vortex dynamics in trapped Bose-Einstein condensate,"We perform numerical simulations of vortex motion in a trapped Bose-Einstein
+condensate by solving the two-dimensional Gross-Pitaevskii Equation in the
+presence of a simple phenomenological model of interaction between the
+condensate and the finite temperature thermal cloud. At zero temperature, the
+trajectories of a single, off - centred vortex precessing in the condensate,
+and of a vortex - antivortex pair orbiting within the trap, excite acoustic
+emission. At finite temperatures the vortices move to the edge of the
+condensate and vanish. By fitting the finite -temperature trajectories, we
+relate the phenomenological damping parameter to the friction coefficients
+$\alpha$ and $\alpha^{'}$, which are used to describe the interaction between
+quantised vortices and the normal fluid in superfluid helium.",0806.2077v2
+2008-06-12,Diversity-induced resonance in a system of globally coupled linear oscillators,"The purpose of this paper to analyze in some detail the arguably simplest
+case of diversity-induced reseonance: that of a system of globally-coupled
+linear oscillators subjected to a periodic forcing. Diversity appears as the
+parameters characterizing each oscillator, namely its mass, internal frequency
+and damping coefficient are drawn from a probability distribution. The main
+ingredients for the diversity-induced-resonance phenomenon are present in this
+system as the oscillators display a variability in the individual responses but
+are induced, by the coupling, to synchronize their responses. A steady state
+solution for this model is obtained. We also determine the conditions under
+which it is possible to find a resonance effect.",0806.2106v1
+2008-08-05,From Equilibrium to Transport Properties of Strongly Correlated Fermi Liquids,"We summarize recent results regarding the equilibrium and non-equilibrium
+behavior of cold dilute atomic gases in the limit in which the two body
+scattering length a goes to infinity. In this limit the system is described by
+a Galilean invariant (non-relativistic) conformal field theory. We discuss the
+low energy effective lagrangian appropriate to the limit a->infinity, and
+compute low energy coefficients using an epsilon-expansion. We also show how to
+combine the effective lagrangian with kinetic theory in order to compute the
+shear viscosity, and compare the kinetic theory predictions to experimental
+results extracted from the damping of collective modes in trapped Fermi gases.",0808.0734v1
+2008-09-09,What can we learn from electromagnetic plasmas about the quark-gluon plasma?,"Ultra-relativistic electromagnetic plasmas can be used for improving our
+understanding of the quark-gluon plasma. In the weakly coupled regime both
+plasmas can be described by transport theoretical and quantum field theoretical
+methods leading to similar results for the plasma properties (dielectric
+tensor, dispersion relations, plasma frequency, Debye screening, transport
+coefficients, damping and particle production rates). In particular, future
+experiments with ultra-relativistic electron-positron plasmas in ultra-strong
+laser fields might open the possibility to test these predictions, e.g. the
+existence of a new fermionic plasma wave (plasmino). In the strongly coupled
+regime electromagnetic plasmas such as complex plasmas can be used as models or
+at least analogies for the quark-gluon plasma possibly produced in relativistic
+heavy-ion experiments. For example, pair correlation functions can be used to
+investigate the equation of state and cross section enhancement for parton
+scattering can be explained.",0809.1507v1
+2008-10-06,Ultrarelativistic Electron-Positron Plasma,"Ultrarelativistic electron-positron plasmas can be produced in high-intensity
+laser fields and play a role in various astrophysical situations. Their
+properties can be calculated using QED at finite temperature. Here we will use
+perturbative QED at finite temperature for calculating various important
+properties, such as the equation of state, dispersion relations of collective
+plasma modes of photons and electrons, Debye screening, damping rates, mean
+free paths, collision times, transport coefficients, and particle production
+rates, of ultrarelativistic electron-positron plasmas. In particular, we will
+focus on electron-positron plasmas produced with ultra-strong lasers.",0810.0909v1
+2009-01-27,"A simple, low-cost, data-logging pendulum built from a computer mouse","Lessons and homework problems involving a pendulum are often a big part of
+introductory physics classes and laboratory courses from high school to
+undergraduate levels. Although laboratory equipment for pendulum experiments is
+commercially available, it is often expensive and may not be affordable for
+teachers on fixed budgets, particularly in developing countries. We present a
+low-cost, easy-to-build rotary sensor pendulum using the existing hardware in a
+ball-type computer mouse. We demonstrate how this apparatus may be used to
+measure both the frequency and coefficient of damping of a simple physical
+pendulum. This easily constructed laboratory equipment makes it possible for
+all students to have hands-on experience with one of the most important simple
+physical systems.",0901.4319v1
+2009-02-18,Frequency dependence of viscous and viscoelastic dissipation in coated micro-cantilevers from noise measurement,"We measure the mechanical thermal noise of soft silicon atomic force
+microscopy cantilevers. Using an interferometric setup, we have a resolution
+down to 1E-14 m/rtHz on a wide spectral range (3 Hz to 1E5 Hz). The low
+frequency behavior depends dramatically on the presence of a reflective
+coating: almost flat spectrums for uncoated cantilevers versus 1/f like trend
+for coated ones. The addition of a viscoelastic term in models of the
+mechanical system can account for this observation. Use of Kramers-Kronig
+relations validate this approach with a complete determination of the response
+of the cantilever: a power law with a small coefficient is found for the
+frequency dependence of viscoelasticity due to the coating, whereas the viscous
+damping due to the surrounding atmosphere is accurately described by the Sader
+model.",0902.3134v2
+2009-03-10,Phonon-phonon interactions and phonon damping in carbon nanotubes,"We formulate and study the effective low-energy quantum theory of interacting
+long-wavelength acoustic phonons in carbon nanotubes within the framework of
+continuum elasticity theory. A general and analytical derivation of all three-
+and four-phonon processes is provided, and the relevant coupling constants are
+determined in terms of few elastic coefficients. Due to the low dimensionality
+and the parabolic dispersion, the finite-temperature density of noninteracting
+flexural phonons diverges, and a nonperturbative approach to their interactions
+is necessary. Within a mean-field description, we find that a dynamical gap
+opens. In practice, this gap is thermally smeared, but still has important
+consequences. Using our theory, we compute the decay rates of acoustic phonons
+due to phonon-phonon and electron-phonon interactions, implying upper bounds
+for their quality factor.",0903.1771v2
+2009-03-30,Breit-Wigner resonances and the quasinormal modes of anti-de Sitter black holes,"The purpose of this short communication is to show that the theory of
+Breit-Wigner resonances can be used as an efficient numerical tool to compute
+black hole quasinormal modes. For illustration we focus on the Schwarzschild
+anti-de Sitter (SAdS) spacetime. The resonance method is better suited to small
+SAdS black holes than the traditional series expansion method, allowing us to
+confirm that the damping timescale of small SAdS black holes for scalar and
+gravitational fields is proportional to r_+^(-2l-2), where r_+ is the horizon
+radius. The proportionality coefficients are in good agreement with analytic
+calculations. We also examine the eikonal limit of SAdS quasinormal modes,
+confirming quantitatively Festuccia and Liu's prediction of the existence of
+very long-lived modes in asymptotically AdS spacetimes. Our results are
+particularly relevant for the AdS/CFT correspondence, since long-lived modes
+presumably dominate the decay timescale of the perturbations.",0903.5311v1
+2009-08-21,Aspects of warm-flat directions,"Considering the mechanism of dissipative slow-roll that has been used in warm
+inflation scenario, we show that dissipation may alter usual cosmological
+scenarios associated with SUSY-flat directions. We mainly consider SUSY-flat
+directions that have strong interactions with non-flat directions and may cause
+strong dissipation both in thermal and non-thermal backgrounds. An example is
+the Affleck-Dine mechanism in which dissipation may create significant (both
+qualitative and quantitative) discrepancies between the conventional scenario
+and the dissipative one. We also discuss several mechanisms of generating
+curvature perturbations in which the dissipative field, which is distinguished
+from the inflaton field, can be used as the source of cosmological
+perturbations. Considering the Morikawa-Sasaki dissipative coefficient, the
+damping caused by the dissipation may be significant for many MSSM flat
+directions even if the dissipation is far from thermal equilibrium.",0908.3059v4
+2009-10-19,Friction force on slow charges moving over supported graphene,"We provide a theoretical model that describes the dielectric coupling of a 2D
+layer of graphene, represented by a polarization function in the Random Phase
+Approximation, and a semi-infinite 3D substrate, represented by a surface
+response function in a non-local formulation. We concentrate on the role of the
+dynamic response of the substrate for low-frequency excitations of the combined
+graphene-substrate system, which give rise to the stopping force on slowly
+moving charges above graphene. A comparison of the dielectric loss function
+with experimental HREELS data for graphene on a SiC substrate is used to
+estimate the damping rate in graphene and to reveal the importance of phonon
+excitations in an insulating substrate. A signature of the hybridization
+between graphene's pi plasmon and the substrate's phonon is found in the
+stopping force. A friction coefficient that is calculated for slow charges
+moving above graphene on a metallic substrate shows an interplay between the
+low-energy single-particle excitations in both systems.",0910.3586v1
+2009-11-15,Effect of three-body loss on itinerant ferromagnetism in an atomic Fermi gas,"A recent experiment has provided the first evidence for itinerant
+ferromagnetism in an ultracold atomic gas of fermions with repulsive
+interactions. However, the gas in this regime is also subject to significant
+three-body loss. We adopt an extended Hertz-Millis theory to account for the
+effect of loss on the transition and on the ferromagnetic state. We find that
+the losses damp quantum fluctuations and thereby significantly increase the
+critical interaction strength needed to induce ferromagnetism. This effect may
+resolve a discrepancy between the experiment and previous theoretical
+predictions of the critical interaction strength. We further illuminate the
+impact of loss by studying the collective spin excitations in the ferromagnet.
+Even in the fully polarized state, where loss is completely suppressed, spin
+waves acquire a decay rate proportional to the three-body loss coefficient.",0911.2839v1
+2009-12-18,Gravitational Instability in Presence of Bulk Viscosity: the Jeans Mass and the Quasi-Isotropic Solution,"This paper focuses on the analysis of the gravitational instability in
+presence of bulk viscosity both in Newtonian regime and in the
+fully-relativistic approach. The standard Jeans Mechanism and the
+Quasi-Isotropic Solution are treated expressing the bulk-viscosity coefficient
+$\zeta$ as a power-law of the fluid energy density $\rho$, i.e.,
+$\zeta=\zo\rho^{s}$. In the Newtonian regime, the perturbation evolution is
+founded to be damped by viscosity and the top-down mechanism of structure
+fragmentation is suppressed. The value of the Jeans Mass remains unchanged also
+in presence of viscosity. In the relativistic approach, we get a power-law
+solution existing only in correspondence to a restricted domain of $\zo$.",0912.3641v1
+2010-01-14,A Theoretical Closure for Turbulent Flows Near Walls,"This paper proposes a simple new closure principle for turbulent shear flows.
+The turbulent flow field is divided into an outer and an inner region. The
+inner region is made up of a log-law region and a wall layer. The wall layer is
+viewed in terms of the well known inrush-sweep-burst sequence observed since
+1967. It is modelled as a transient laminar sub-boundary layer, which obeys the
+Stokes solution for an impulsively started flat plate. The wall layer may also
+be modelled with a steady state solution by adding a damping function to the
+log-law.
+  Closure is achieved by matching the unsteady and steady state solutions at
+the edge of the wall layer. This procedure in effect feeds information about
+the transient coherent structures back into the time-averaged solution and
+determines theoretically the numerical coefficient of the logarithmic law of
+the wall
+  The method gives a new technique for writing accurate wall functions, valid
+for all Reynolds numbers, in computer fluid dynamics (CFD) programmes.
+  Keywords: Reynolds equations, modelling, closure technique, wall layer,
+log-law, CFD.",1001.2353v1
+2010-02-23,Bulk viscosity in hyperonic star and r-mode instability,"We consider a rotating neutron star with the presence of hyperons in its
+core, using an equation of state in an effective chiral model within the
+relativistic mean field approximation. We calculate the hyperonic bulk
+viscosity coefficient due to nonleptonic weak interactions. By estimating the
+damping timescales of the dissipative processes, we investigate its role in the
+suppression of gravitationally driven instabilities in the $r$-mode. We observe
+that $r$-mode instability remains very much significant for hyperon core
+temperature of around $10^8 $K, resulting in a comparatively larger instability
+window. We find that such instability can reduce the angular velocity of the
+rapidly rotating star considerably upto $\sim0.04 \Omega_K$, with $\Omega_K$ as
+the Keplerian angular velocity.",1002.4253v1
+2010-03-03,Phonon lineshapes in atom-surface scattering,"Phonon lineshapes in atom-surface scattering are obtained from a simple
+stochastic model based on the so-called Caldeira-Leggett Hamiltonian. In this
+single-bath model, the excited phonon resulting from a creation or annihilation
+event is coupled to a thermal bath consisting of an infinite number of harmonic
+oscillators, namely the bath phonons. The diagonalization of the corresponding
+Hamiltonian leads to a renormalization of the phonon frequencies in terms of
+the phonon friction or damping coefficient. Moreover, when there are adsorbates
+on the surface, this single-bath model can be extended to a two-bath model
+accounting for the effect induced by the adsorbates on the phonon lineshapes as
+well as their corresponding lineshapes.",1003.0790v2
+2010-03-30,Superfluid hyperon bulk viscosity and the r-mode instability of rotating neutron stars,"In order to establish whether the unstable r-modes in a rotating neutron star
+provide a detectable source of gravitational waves, we need to understand the
+details of the many dissipative processes that tend to counteract the
+instability. It has been established that the bulk viscosity due to exotic
+particles, like hyperons, may be particularly important in this respect.
+However, the effects of hyperon superfluidity have so far not been fully
+accounted for. While the associated suppression of the reaction rates that give
+rise to the bulk viscosity has been estimated, superfluid aspects of the fluid
+dynamics have not been considered. In this paper we determine the r-mode
+instability window for a neutron star with a $\Sigma^{-}$ hyperon core, using
+the appropriate multifluid formalism including, for the first time, the effect
+of the ""superfluid"" bulk viscosity coefficients. We demonstrate that, even
+though the extra terms may increase the bulk viscosity damping somewhat, their
+presence does not affect the qualitative features of the r-mode instability
+window.",1003.5849v1
+2010-05-07,r-modes in low temperature colour-flavour-locked superconducting quark star,"We present the first multi-fluid analysis of a dense neutron star core with a
+deconfined colour-flavour-locked superconducting quark component. Accounting
+only for the condensate and (finite temperature) phonons, we make progress by
+taking over results for superfluid $^4$He. The resultant two-fluid model
+accounts for a number of additional viscosity coefficients (compared to the
+Navier-Stokes equations) and we show how they enter the dissipation analysis
+for an oscillating star. We provide simple estimates for the gravitational-wave
+driven r-mode instability, demonstrating that the various phonon processes that
+we consider are not effective damping agents. Even though the results are
+likely of little direct astrophysical importance (since we consider an overly
+simplistic stellar model) our analysis represents significant technical
+progress, laying the foundation for more detailed numerical studies and
+preparing the ground for the inclusion of additional aspects (in particular
+associated with kaons) of the problem.",1005.1163v1
+2010-06-25,Molecular Dynamics at Low Time Resolution,"The internal dynamics of macro-molecular systems is characterized by widely
+separated time scales, ranging from fraction of ps to ns. In ordinary molecular
+dynamics simulations, the elementary time step dt used to integrate the
+equation of motion needs to be chosen much smaller of the shortest time scale,
+in order not to cut-off important physical effects. We show that, in systems
+obeying the over-damped Langevin Eq., the fast molecular dynamics which occurs
+at time scales smaller than dt can be analytically integrated out and gives
+raise to a time-dependent correction to the diffusion coefficient, which we
+rigorously compute. The resulting effective Langevin equation describes by
+construction the same long-time dynamics, but has a lower time resolution
+power, hence it can be integrated using larger time steps dt. We illustrate and
+validate this method by studying the diffusion of a point-particle in a
+one-dimensional toy-model and the denaturation of a protein.",1006.5045v1
+2010-07-15,Universal Quantum Viscosity in a Unitary Fermi Gas,"A Fermi gas of atoms with resonant interactions is predicted to obey
+universal hydrodynamics, where the shear viscosity and other transport
+coefficients are universal functions of the density and temperature. At low
+temperatures, the viscosity has a universal quantum scale $\hbar n$ where $n$
+is the density, while at high temperatures the natural scale is $p_T^3/\hbar^2$
+where $p_T$ is the thermal momentum. We employ breathing mode damping to
+measure the shear viscosity at low temperature. At high temperature $T$, we
+employ anisotropic expansion of the cloud to find the viscosity, which exhibits
+precise $T^{3/2}$ scaling. In both experiments, universal hydrodynamic
+equations including friction and heating are used to extract the viscosity. We
+estimate the ratio of the shear viscosity to the entropy density and compare to
+that of a perfect fluid.",1007.2625v2
+2010-07-26,Phase-Field Reaction-Pathway Kinetics of Martensitic Transformations in a Model Fe3Ni Alloy,"A three-dimensional phase-field approach to martensitic transformations that
+uses reaction pathways in place of a Landau potential is introduced and applied
+to a model of Fe3Ni. Pathway branching involves an unbounded set of variants
+through duplication and rotations by the rotation point groups of the austenite
+and martensite phases. Path properties, including potential energy and elastic
+tensors, are calibrated by molecular statics. Acoustic waves are dealt with via
+a splitting technique between elastic and dissipative behaviors in a
+large-deformation framework. The sole free parameter of the model is the
+damping coefficient associated to transformations, tuned by comparisons with
+molecular dynamics simulations. Good quantitative agreement is then obtained
+between both methods.",1007.4515v1
+2010-08-07,Fermi acceleration and suppression of Fermi acceleration in a time-dependent Lorentz Gas,"We study some dynamical properties of a Lorentz gas. We have considered both
+the static and time dependent boundary. For the static case we have shown that
+the system has a chaotic component characterized with a positive Lyapunov
+Exponent. For the time-dependent perturbation we describe the model using a
+four-dimensional nonlinear map. The behaviour of the average velocity is
+considered in two situations (i) non-dissipative and (ii) dissipative. Our
+results show that the unlimited energy growth is observed for the
+non-dissipative case. However, when dissipation, via damping coefficients, is
+introduced the senary changes and the unlimited engergy growth is suppressed.
+The behaviour of the average velocity is described using scaling approach.",1008.1344v2
+2010-11-01,Terahertz surface plasmons in optically pumped graphene structures,"We analyze the surface plasmons (SPs) propagating along the optically pumped
+single-graphene layer (SGL) and multiple-graphene layer (MGL) structures. It is
+shown that at sufficiently strong optical pumping when the real part of dynamic
+conductivity of SGL and MGL structures becomes negative in the terahertz (THz)
+range of frequencies due to the interband population inversion, the damping of
+the THz SPs can give way to their amplification. This effect can be used in
+graphene-based THz lasers and other devices. Due to relatively small SP group
+velocity, the absolute value of their absorption coefficient (SP gain) can be
+large, substantially exceeding that of the optically pumped structures with the
+dielectric waveguide. The comparison of the SGL and MGL structures shows that
+to maximize the SP gain the number of GL layers should be properly choosen.",1011.0238v1
+2010-11-01,In-flight dissipation as a mechanism to suppress Fermi acceleration,"Some dynamical properties of time-dependent driven elliptical-shaped billiard
+are studied. It was shown that for the conservative time-dependent dynamics the
+model exhibits the Fermi acceleration [Phys. Rev. Lett. 100, 014103 (2008)]. On
+the other hand, it was observed that damping coefficients upon collisions
+suppress such phenomenon [Phys. Rev. Lett. 104, 224101 (2010)]. Here, we
+consider a dissipative model under the presence of in-flight dissipation due to
+a drag force which is assumed to be proportional to the square of the
+particle's velocity. Our results reinforce that dissipation leads to a phase
+transition from unlimited to limited energy growth. The behaviour of the
+average velocity is described using scaling arguments.",1011.0419v1
+2010-12-29,Dependence of boundary lubrication on the misfit angle between the sliding surfaces,"Using molecular dynamics based on Langevin equations with a coordinate- and
+velocity-dependent damping coefficient, we study the frictional properties of a
+thin layer of ""soft"" lubricant (where the interaction within the lubricant is
+weaker than the lubricant-substrate interaction) confined between two solids.
+At low driving velocities the system demonstrates stick-slip motion. The
+lubricant may or may not be melted during sliding, thus exhibiting either the
+""liquid sliding"" (LS) or the ""layer over layer sliding"" (LoLS) regimes. The
+LoLS regime mainly operates at low sliding velocities. We investigate the
+dependence of friction properties on the misfit angle between the sliding
+surfaces and calculate the distribution of static frictional thresholds for a
+contact of polycrystalline surfaces.",1012.5922v1
+2010-12-31,Structural optimization of the Ziegler's pendulum: singularities and exact optimal solutions,"Structural optimization of non-conservative systems with respect to stability
+criteria is a research area with important applications in fluid-structure
+interactions, friction-induced instabilities, and civil engineering. In
+contrast to optimization of conservative systems where rigorously proven
+optimal solutions in buckling problems have been found, for non-conservative
+optimization problems only numerically optimized designs were reported. The
+proof of optimality in the non-conservative optimization problems is a
+mathematical challenge related to multiple eigenvalues, singularities on the
+stability domain, and non-convexity of the merit functional. We present a study
+of the optimal mass distribution in a classical Ziegler's pendulum where local
+and global extrema can be found explicitly. In particular, for the undamped
+case, the two maxima of the critical flutter load correspond to a vanishing
+mass either in a joint or at the free end of the pendulum; in the minimum, the
+ratio of the masses is equal to the ratio of the stiffness coefficients. The
+role of the singularities on the stability boundary in the optimization is
+highlighted and extension to the damped case as well as to the case of higher
+degrees of freedom is discussed.",1101.0246v1
+2011-01-24,Boundary crisis and suppression of Fermi acceleration in a dissipative two dimensional non-integrable time-dependent billiard,"Some dynamical properties for a dissipative time-dependent oval-shaped
+billiard are studied. The system is described in terms of a four-dimensional
+nonlinear mapping. Dissipation is introduced via inelastic collisions of the
+particle with the boundary, thus implying that the particle has a fractional
+loss of energy upon collision. The dissipation causes profound modifications in
+the dynamics of the particle as well as in the phase space of the non
+dissipative system. In particular, inelastic collisions can be assumed as an
+efficient mechanism to suppress Fermi acceleration of the particle. The
+dissipation also creates attractors in the system, including chaotic. We show
+that a slightly modification of the intensity of the damping coefficient yields
+a drastic and sudden destruction of the chaotic attractor, thus leading the
+system to experience a boundary crisis. We have characterized such a boundary
+crisis via a collision of the chaotic attractor with its own basin of
+attraction and confirmed that inelastic collisions do indeed suppress Fermi
+acceleration in two-dimensional time dependent billiards.",1101.4593v1
+2011-04-14,Phenomenological modeling of long range noncontact friction in micro- and nanoresonators,"Motivated by the results of an experiment using atomic force microscopy
+performed by Gotsmann and Fuchs [Phys. Rev. Lett. {\bf 86}, 2597 (2001)], where
+a strong energy loss due to the tip-sample interaction was measured, we
+investigate the potential implications of this energy loss channel to the
+quality factor of suspended micro- and nanoresonators. Because the observed
+tip-sample dissipation remains without a satisfactory theoretical explanation,
+two phenomenological models are proposed to generalize the experimental
+observations. A minimal phenomenological model simply extends for larger
+separations the range of validity of the power law found experimentally for the
+damping coefficient. A more elaborate phenomenological model assumes that the
+noncontact friction is a consequence of the Casimir force acting between the
+closely spaced surfaces. Both models provide quantitative results for the
+noncontact friction between any two objects which are then used to estimate the
+energy loss for suspended bar micro- and nanoresonators. Its is concluded that
+the energy loss due to the unknown mechanism has the potential to seriously
+restrict the quality factor of both micro- and nanoresonators.",1104.2832v2
+2011-05-03,Nonequilibrium chiral fluid dynamics including dissipation and noise,"We present a consistent theoretical approach for the study of nonequilibrium
+effects in chiral fluid dynamics within the framework of the linear sigma model
+with constituent quarks. Treating the quarks as an equilibrated heat bath we
+use the influence functional formalism to obtain a Langevin equation for the
+sigma field. This allows us to calculate the explicit form of the damping
+coefficient and the noise correlators. For a selfconsistent derivation of both
+the dynamics of the sigma field and the quark fluid we have to employ the 2PI
+(two-particle irreducible) effective action formalism. The energy dissipation
+from the field to the fluid is treated in the exact formalism of the 2PI
+effective action where a conserved energy-momentum tensor can be constructed.
+We derive its form and comment on approximations generating additional terms in
+the energy-momentum balance of the entire system.",1105.0622v1
+2011-05-05,Long-range three-body atom-diatom potential for doublet Li${}_3$,"An accurate long-range {\em ab initio} potential energy surface has been
+calculated for the ground state ${}^2A'$ lithium trimer in the frozen diatom
+approximation using all electron RCCSD(T). The {\em ab initio} energies are
+corrected for basis set superposition error and extrapolated to the complete
+basis limit. Molecular van der Waals dispersion coefficients and three-body
+dispersion damping terms for the atom-diatomic dissociation limit are presented
+from a linear least squares fit and shown to be an essentially exact
+representation of the {\em ab initio} surface at large range.",1105.1090v2
+2011-05-12,Searching for Perfect Fluids: Quantum Viscosity in a Universal Fermi Gas,"We measure the shear viscosity in a two-component Fermi gas of atoms, tuned
+to a broad s-wave collisional (Feshbach) resonance. At resonance, the atoms
+strongly interact and exhibit universal behavior, where the equilibrium
+thermodynamic properties and the transport coefficients are universal functions
+of the density $n$ and temperature $T$. We present a new calibration of the
+temperature as a function of global energy, which is directly measured from the
+cloud profiles. Using the calibration, the trap-averaged shear viscosity in
+units of $\hbar\,n$ is determined as a function of the reduced temperature at
+the trap center, from nearly the ground state to the unitary two-body regime.
+Low temperature data is obtained from the damping rate of the radial breathing
+mode, while high temperature data is obtained from hydrodynamic expansion
+measurements. We also show that the best fit to the high temperature expansion
+data is obtained for a vanishing bulk viscosity. The measured trap-averaged
+entropy per particle and shear viscosity are used to estimate the ratio of the
+shear viscosity to the entropy density, which is compared that conjectured for
+a perfect fluid.",1105.2496v1
+2011-05-21,Stochastic population oscillations in spatial predator-prey models,"It is well-established that including spatial structure and stochastic noise
+in models for predator-prey interactions invalidates the classical
+deterministic Lotka-Volterra picture of neutral population cycles. In contrast,
+stochastic models yield long-lived, but ultimately decaying erratic population
+oscillations, which can be understood through a resonant amplification
+mechanism for density fluctuations. In Monte Carlo simulations of spatial
+stochastic predator-prey systems, one observes striking complex spatio-temporal
+structures. These spreading activity fronts induce persistent correlations
+between predators and prey. In the presence of local particle density
+restrictions (finite prey carrying capacity), there exists an extinction
+threshold for the predator population. The accompanying continuous
+non-equilibrium phase transition is governed by the directed-percolation
+universality class. We employ field-theoretic methods based on the Doi-Peliti
+representation of the master equation for stochastic particle interaction
+models to (i) map the ensuing action in the vicinity of the absorbing state
+phase transition to Reggeon field theory, and (ii) to quantitatively address
+fluctuation-induced renormalizations of the population oscillation frequency,
+damping, and diffusion coefficients in the species coexistence phase.",1105.4242v1
+2011-06-17,Sequential vibrational resonance in multistable systems,"The phenomenon of sequential vibrational resonance existed in a multistable
+system that is excited by both high- and low-frequency signals is reported. By
+the method of direct separation of motions, the theoretical investigation on
+vibrational resonance is conducted in both cases of underdamped and overdamped,
+and the analytical predictions are in good agreement with the numerical
+simulations. In view of the theoretical results, the zero-order Bessel function
+related to the high-frequency signal is included in the renormalized resonant
+frequency, and which leads to the appearance of the sequential vibrational
+resonance. In the case of underdamped system with small damping coefficient,
+the resonance occurs in a series of discrete parameter regions. The sequential
+vibrational resonance is different from the traditional multiple vibrational
+resonance, because its appearance is much more regular. The results in this
+work may be helpful in the field of signal processing electronics, especially
+for dealing with the very-low-frequency signal.",1106.3431v1
+2011-10-27,Existence of global strong solutions for the shallow-water equations with large initial data,"This work is devoted to the study of a viscous shallow-water system with
+friction and capillarity term. We prove in this paper the existence of global
+strong solutions for this system with some choice of large initial data when
+$N\geq 2$ in critical spaces for the scaling of the equations. More precisely,
+we introduce as in \cite{Hprepa} a new unknown,\textit{a effective velocity}
+$v=u+\mu\n\ln h$ ($u$ is the classical velocity and $h$ the depth variation of
+the fluid) with $\mu$ the viscosity coefficient which simplifies the system and
+allow us to cancel out the coupling between the velocity $u$ and the depth
+variation $h$. We obtain then the existence of global strong solution if
+$m_{0}=h_{0}v_{0}$ is small in $B^{\N-1}_{2,1}$ and $(h_{0}-1)$ large in
+$B^{\N}_{2,1}$. In particular it implies that the classical momentum
+$m_{0}^{'}=h_{0} u_{0}$ can be large in $B^{\N-1}_{2,1}$, but small when we
+project $m_{0}^{'}$ on the divergence field. These solutions are in some sense
+\textit{purely compressible}. We would like to point out that the friction term
+term has a fundamental role in our work inasmuch as coupling with the pressure
+term it creates a damping effect on the effective velocity.",1110.6100v1
+2011-10-28,Nonlinear instability of solutions in parabolic and hyperbolic diffusion,"We consider semilinear evolution equations of the form $a(t)\partial_{tt}u +
+b(t) \partial_t u + Lu = f(x,u)$ and $b(t) \partial_t u + Lu = f(x,u),$ with
+possibly unbounded $a(t)$ and possibly sign-changing damping coefficient
+$b(t)$, and determine precise conditions for which linear instability of the
+steady state solutions implies nonlinear instability. More specifically, we
+prove that linear instability with an eigenfunction of fixed sign gives rise to
+nonlinear instability by either exponential growth or finite-time blow-up. We
+then discuss a few examples to which our main theorem is immediately
+applicable, including evolution equations with supercritical and exponential
+nonlinearities.",1110.6240v3
+2011-11-09,Numerical stability of the Z4c formulation of general relativity,"We study numerical stability of different approaches to the discretization of
+a conformal decomposition of the Z4 formulation of general relativity. We
+demonstrate that in the linear, constant coefficient regime a novel
+discretization for tensors is formally numerically stable with a method of
+lines time-integrator. We then perform a full set of apples with apples tests
+on the non-linear system, and thus present numerical evidence that both the new
+and standard discretizations are, in some sense, numerically stable in the
+non-linear regime. The results of the Z4c numerical tests are compared with
+those of BSSNOK evolutions. We typically do not employ the Z4c constraint
+damping scheme and find that in the robust stability and gauge wave tests the
+Z4c evolutions result in lower constraint violation at the same resolution as
+the BSSNOK evolutions. In the gauge wave tests we find that the Z4c evolutions
+maintain the desired convergence factor over many more light-crossing times
+than the BSSNOK tests. The difference in the remaining tests is marginal.",1111.2177v1
+2012-01-30,Non-contact Friction and Relaxational Dynamics of Surface Defects,"Motion of cantilever near sample surfaces exhibits additional friction even
+before two bodies come into mechanical contact. Called non-contact friction
+(NCF), this friction is of great practical importance to the ultrasensitive
+force detection measurements. Observed large NCF of a micron-scale cantilever
+found anomalously large damping that exceeds theoretical predictions by 8-11
+orders of magnitude. This finding points to contribution beyond fluctuating
+electromagnetic fields within van der Waals approach. Recent experiments
+reported by Saitoh et al. (Phys. Rev. Lett. 105, 236103 (2010)) also found
+nontrivial distance dependence of NCF. Motivated by these observations, we
+propose a mechanism based on the coupling of cantilever to the relaxation
+dynamics of surface defects. We assume that the surface defects couple to the
+cantilever tip via spin-spin coupling and their spin relaxation dynamics gives
+rise to the backaction terms and modifies both the friction coefficient and the
+spring constant. We explain the magnitude, as well as the distance dependence
+of the friction due to these backaction terms. Reasonable agreement is found
+with the experiments.",1201.6378v1
+2012-02-09,Casimir-Polder interaction of fullerene molecules with surfaces,"We calculate the thermal Casimir--Polder potential of C60 and C70 fullerene
+molecules near gold and silicon nitride surfaces, motivated by their relevance
+for molecular matter wave interference experiments. We obtain the coefficients
+governing the asymptotic power laws of the interaction in the thermal, retarded
+and nonretarded distance regimes and evaluate the full potential numerically.
+The interaction is found to be dominated by electronic transitions, and hence
+independent of the internal temperature of the molecules. The contributions
+from phonon transitions, which are affected by the molecular temperature, give
+rise to only a small correction. Moreover, we find that the sizeable molecular
+line widths of thermal fullerenes may modify the nonretarded interaction,
+depending on the model used. Detailed measurements of the nonretarded potential
+of fullerene thus allow one to distinguish between different theories of
+incorporating damping.",1202.1982v1
+2012-04-30,New integrability case for the Riccati equation,"A new integrability condition of the Riccati equation
+$dy/dx=a(x)+b(x)y+c(x)y^{2}$ is presented. By introducing an auxiliary equation
+depending on a generating function $f(x)$, the general solution of the Riccati
+equation can be obtained if the coefficients $a(x)$, $b(x)$, $c(x)$, and the
+function $f(x)$ satisfy a particular constraint. The validity and reliability
+of the method are tested by obtaining the general solutions of some Riccati
+type differential equations. Some applications of the integrability conditions
+for the case of the damped harmonic oscillator with time dependent frequency,
+and for solitonic wave, are briefly discussed.",1204.6546v1
+2012-06-23,Superlattice formed by quantum-dot sheets: density of states and IR absorption,"Low-energy continuous states of electron in heterosrtucture with periodically
+placed quantum-dot sheets are studied theoretically. The Green's function of
+electron is governed by the Dyson equation with the self-energy function which
+is determined the boundary conditions at quantum-dot sheets with weak damping
+in low-energy region. The parameters of superlattice formed by quantum-dot
+sheets are determined using of the short-range model of quantum dot. The
+density of states and spectral dependencies of the anisotropic absorption
+coefficient under mid-IR transitions from doped quantum dots into miniband
+states of superlattice strongly depend on dot concentration and on period of
+sheets. These dependencies can be used for characterization of the multi-layer
+structure and they determine parameters of different optoelectronic devices
+exploiting vertical transport of carriers through quantum-dot sheets.",1206.5418v1
+2012-07-27,Spin transition rates in nanowire superlattices: Rashba spin-orbit coupling effects,"We investigate the influence of Rashba spin-orbit coupling in a parabolic
+nanowire modulated by longitudinal periodic potential. The modulation potential
+can be obtained from realistically grown supperlattices (SLs). Our study shows
+that the Rashba spin-orbit interaction induces the level crossing point in the
+parabolic nanowire SLs. We estimate large anticrossing width (approximately 117
+$\mu eV$) between singlet-triplet states. We study the phonon and
+electromagnetic field mediated spin transition rates in the parabolic nanowire
+SLs. We report that the phonon mediated spin transition rate is several order
+of magnitude larger than the electromagnetic field mediated spin transition
+rate. Based on the Feynman disentangling technique, we find the exact spin
+transition probability. For the case wave vector $k=0$, we report that the
+transition probability can be tuned in the form of resonance at fixed time
+interval. For the general case ($k\neq 0$), we solve the Riccati equation and
+find that the arbitrary values of $k$ induces the damping in the transition
+probability. At large value of Rashba spin-orbit coupling coefficients for
+($k\neq 0$), spin transition probability freezes.",1207.6580v2
+2012-09-24,Non-stationary Magnetic Microstructures in Stellar Thin Accretion Discs,"We examine the morphology of magnetic structures in thin plasma accretion
+discs, generalizing a stationary ideal MHD model to the time-dependent
+visco-resistive case. Our analysis deals with small scale perturbations to a
+central dipole-like magnetic field, which give rise -- as in the ideal case --
+to the periodic modulation of magnetic flux surfaces along the radial
+direction, corresponding to the formation of a toroidal current channels
+sequence. These microstructures suffer an exponential damping in time because
+of the non-zero resistivity coefficient, allowing us to define a configuration
+lifetime which mainly depends on the midplane temperature and on the length
+scale of the structure itself. By means of this lifetime we show that the
+microstructures can exist within the inner region of stellar discs in a precise
+range of temperatures, and that their duration is consistent with local
+transient processes (minutes to hours).",1209.5227v2
+2013-03-22,Scattering Rates For Leptogenesis: Damping of Lepton Flavour Coherence and Production of Singlet Neutrinos,"Using the Closed-Time-Path approach, we perform a systematic leading order
+calculation of the relaxation rate of flavour correlations of left-handed
+Standard Model leptons. This quantity is of pivotal relevance for flavoured
+Leptogenesis in the Early Universe, and we find it to be 5.19*10^-3 T at T=10^7
+GeV and 4.83*10^-3 T at T=10^13 GeV. These values apply to the Standard Model
+with a Higgs-boson mass of 125 GeV. The dependence of the numerical coefficient
+on the temperature T is due to the renormalisation group running. The leading
+linear and logarithmic dependencies of the flavour relaxation rate on the gauge
+and top-quark couplings are extracted, such that the results presented in this
+work can readily be applied to extensions of the Standard Model. We also derive
+the production rate of light (compared to the temperature) sterile right-handed
+neutrinos, a calculation that relies on the same methods. We confirm most
+details of earlier results, but find a substantially larger contribution from
+the t-channel exchange of fermions.",1303.5498v1
+2013-06-18,Spinor dynamics in an antiferromagnetic spin-1 thermal Bose gas,"We present experimental observations of coherent spin-population oscillations
+in a cold thermal, Bose gas of spin-1 sodium-23 atoms. The population
+oscillations in a multi-spatial-mode thermal gas have the same behavior as
+those observed in a single-spatial-mode antiferromagnetic spinor Bose Einstein
+condensate. We demonstrate this by showing that the two situations are
+described by the same dynamical equations, with a factor of two change in the
+spin-dependent interaction coefficient, which results from the change to
+particles with distinguishable momentum states in the thermal gas. We compare
+this theory to the measured spin population evolution after times up to a few
+hundreds of ms, finding quantitative agreement with the amplitude and period.
+We also measure the damping time of the oscillations as a function of magnetic
+field.",1306.4255v1
+2013-06-19,Soliton dynamics in an extended nonlinear Schrodinger equation with a spatial counterpart of the stimulated Raman scattering,"Dynamics of solitons is considered in the framework of the extended nonlinear
+Schrodinger equation (NLSE), which is derived from a system of Zakharov's type
+for the interaction between high- and low-frequency (HF and LF) waves, in which
+the LF field is subject to diffusive damping. The model may apply to the
+propagation of HF waves in plasmas. The resulting NLSE includes a
+pseudo-stimulated-Raman-scattering (PSRS) term, i.e., a spatial-domain
+counterpart of the SRS term which is well known as an ingredient of the
+temporal-domain NLSE in optics. Also included is inhomogeneity of the spatial
+second-order diffraction (SOD). It is shown that the wavenumber downshift of
+solitons, caused by the PSRS, may be compensated by an upshift provided by the
+SOD whose coefficient is a linear function of the coordinate. An analytical
+solution for solitons is obtained in an approximate form. Analytical and
+numerical results agree well, including the predicted balance between the PSRS
+and the linearly inhomogeneous SOD.",1306.4550v1
+2013-09-18,On an auto-controlled global existence scheme of the incompressible Navier Stokes equation,"We propose a global scheme for the incompressible Navier Stokes equation,
+where at each time step a damping potential term is introduced via a time
+dilation transformation of the equation itself. This leads a global upper
+bounds of the value function and its spatial derivatives. The regularity is
+limited only by the regularity of the viscosity coefficient function and by the
+regularity and polynomial decay of the data. On an analytical level the scheme
+proposed is an alternative to schemes with external control functions.",1309.4824v11
+2013-10-21,Cosmic ray propagation in galactic turbulence,"We revisit propagation of galactic cosmic rays (CRs) in light of recent
+advances in CR diffusion theory in realistic interstellar turbulence. We use a
+tested model of turbulence in which it has been shown that fast modes dominate
+scattering of CRs. As a result, propagation becomes inhomogeneous and
+environment dependent. By adopting the formalism of the nonlinear theory
+developed by Yan & Lazarian, we calculate the diffusion of CRs
+self-consistently from first principles. We assume a two- phase model for the
+Galaxy to account for different damping mechanisms of the fast modes, and we
+find that the energy dependence of the diffusion coefficient is mainly affected
+by medium properties. We show that it gives a correct framework to interpret
+some of the recent CR puzzles.",1310.5732v2
+2013-10-23,Spectroscopic investigation of local mechanical impedance of living cells,"The mechanical properties of PC12 living cells have been studied at the
+nanoscale with a Force Feedback Microscope using two experimental approaches.
+Firstly, the local mechanical impedance of the cell membrane has been mapped
+simultaneously to the cell morphology at constant force. As the force of the
+interaction is gradually increased, we observed the appearance of the
+sub-membrane cytoskeleton. We shall compare the results obtained with this
+method with the measurement of other existing techniques. Secondly, a
+spectroscopic investigation has been performed varying the indentation of the
+tip in the cell membrane and consequently the force applied on it. In contrast
+with conventional dynamic atomic force microscopy techniques, here the small
+oscillation amplitude of the tip is not necessarily imposed at the cantilever
+first eigenmode. This allows the user to arbitrarily choose the excitation
+frequency in developing spectroscopic AFM techniques. The mechanical response
+of the PC12 cell membrane is found to be frequency dependent in the 1 kHz - 10
+kHz range. The damping coefficient is reproducibly observed to decrease when
+the excitation frequency is increased.",1310.6201v1
+2013-11-21,Note on the super inflation in loop quantum cosmology,"Phenomenological effect of the super-inflation in loop quantum cosmology
+(LQC) is discussed. We investigate the case that the Universe is filled with
+the interacting field between massive scalar field and radiation. Considering
+the damping coefficient $\Gamma$ as a constant, the changes of the scale factor
+during super-inflation with four different initial conditions are discussed,
+and we find that the changes of the scale factor depends on the initial values
+of energy density of the scalar field and radiation at the bounce point. But no
+matter which initial condition is chosen, the radiation always dominated at the
+late time. Moreover, we investigate whether the super-inflation can provide
+enough e-folding number. For the super-inflation starts from the quantum bounce
+point, the initial value of Hubble parameter $H(t_i)\sim0$, then it is possible
+to solve the flatness problem and horizon problem. As an example, following the
+method of \cite{Amoros-prd} to calculate particle horizon on the condition that
+the radiation dominated at bounce point, and we find that the Universe has had
+enough time to be homogeneous and isotopic.",1311.5325v1
+2013-12-10,Delaying the waterfall transition in warm hybrid inflation,"We analyze the dynamics and observational predictions of supersymmetric
+hybrid inflation in the warm regime, where dissipative effects are mediated by
+the waterfall fields and their subsequent decay into light degrees of freedom.
+This produces a quasi-thermal radiation bath with a slowly-varying temperature
+during inflation and further damps the inflaton's motion, thus prolonging
+inflation. As in the standard supercooled scenario, inflation ends when the
+waterfall fields become tachyonic and can no longer sustain a nearly constant
+vacuum energy, but the interaction with the radiation bath makes the waterfall
+fields effectively heavier and delays the phase transition to the
+supersymmetric minimum. In this work, we analyze for the first time the effects
+of finite temperature corrections and SUSY mass splittings on the quantum
+effective potential and the resulting dissipation coefficient. We show, in
+particular, that dissipation can significantly delay the onset of the tachyonic
+instability to yield 50-60 e-folds of inflation and an observationally
+consistent primordial spectrum, which is not possible in the standard
+supercooled regime when inflation is driven by radiative corrections.",1312.2961v1
+2013-12-11,Modelling of the optical properties of silver with use of six fitting parameters,"We propose a realistic model of the optical properties of silver, in which
+inter-band transition with a threshold energy of ~ 4 eV is described
+phenomenologically by an ensemble of oscillators with same damping constant and
+a certain distribution of resonant frequencies in the interband transition
+threshold to infinity. The contribution of the conduction electrons in the
+dielectric function is determined by the Drude formula. The proposed model
+actually contains the features of both the Drude-Lorentz model (Raki\'c et al.
+1998) and Tauc-Lorentz model (Jian-Hong Qiu et al. 2005). However, unlike these
+works proposed model contains only six fitting parameters, with the square root
+of the mean square deviation of the absorption coefficient and refractive index
+of silver from the experimental values in the range of 0.6 nm - 6.0 nm being of
+the order of 0.05.",1312.3100v1
+2014-02-17,"Spatio-temporal dynamics of an active, polar, viscoelastic ring","Constitutive equations for a one-dimensional, active, polar, viscoelastic
+liquid are derived by treating the strain field as a slow hydrodynamic
+variable. Taking into account the couplings between strain and polarity allowed
+by symmetry, the hydrodynamics of an active, polar, viscoelastic body include
+an evolution equation for the polarity field that generalizes the damped
+Kuramoto-Sivashinsky equation. Beyond thresholds of the active coupling
+coefficients between the polarity and the stress or the strain rate,
+bifurcations of the homogeneous state lead first to stationary waves, then to
+propagating waves of the strain, stress and polarity fields. I argue that these
+results are relevant to living matter, and may explain rotating actomyosin
+rings in cells and mechanical waves in epithelial cell monolayers.",1402.3987v1
+2014-05-14,An exactly solvable $\mathcal{PT}$-symmetric dimer from a Hamiltonian system of nonlinear oscillators with gain and loss,"We show that a pair of coupled nonlinear oscillators, of which one oscillator
+has positive and the other one negative damping of equal rate, can form a
+Hamiltonian system. Small-amplitude oscillations in this system are governed by
+a $\mathcal{PT}$-symmetric nonlinear Schr\""odinger dimer with linear and cubic
+coupling. The dimer also represents a Hamiltonian system and is found to be
+exactly solvable in elementary functions. We show that the nonlinearity softens
+the $\mathcal{PT}$-symmetry breaking transition in the nonlinearly-coupled
+dimer: stable periodic and quasiperiodic states with large enough amplitudes
+persist for an arbitrarily large value of the gain-loss coefficient.",1405.3588v2
+2014-07-02,Basins of attraction in forced systems with time-varying dissipation,"We consider dissipative periodically forced systems and investigate cases in
+which having information as to how the system behaves for constant dissipation
+may be used when dissipation varies in time before settling at a constant final
+value. First, we consider situations where one is interested in the basins of
+attraction for damping coefficients varying linearly between two given values
+over many different time intervals: we outline a method to reduce the
+computation time required to estimate numerically the relative areas of the
+basins and discuss its range of applicability. Second, we observe that
+sometimes very slight changes in the time interval may produce abrupt large
+variations in the relative areas of the basins of attraction of the surviving
+attractors: we show how comparing the contracted phase space at a time after
+the final value of dissipation has been reached with the basins of attraction
+corresponding to that value of constant dissipation can explain the presence of
+such variations. Both procedures are illustrated by application to a pendulum
+with periodically oscillating support.",1407.0556v1
+2014-09-24,Scaling laws for the bifurcation-escape rate in a nanomechanical resonator,"We report on experimental and theoretical studies of the fluctuation-induced
+escape time from a metastable state of a nanomechanical Duffing resonator in
+cryogenic environment. By tuning in situ the non-linear coefficient $\gamma$ we
+could explore a wide range of the parameter space around the bifurcation point,
+where the metastable state becomes unstable. We measured in a relaxation
+process the distribution of the escape times. We have been able to verify its
+exponential distribution and extract the escape rate $\Gamma$. We investigated
+the scaling of $\Gamma$ with respect to the distance to the bifurcation point
+and $\gamma$, finding an unprecedented quantitative agreement with the
+theoretical description of the stochastic problem. Simple power scaling laws
+turn out to hold in a large region of the parameter's space, as anticipated by
+recent theoretical predictions. These unique findings, implemented in a model
+dynamical system, are relevant to all systems experiencing under-damped
+saddle-node bifurcation.",1409.6971v3
+2014-09-30,Numerical Simulation of Two Dimentional sine-Gordon Solitons Using the Modified Cubic B-Spline Differential Quadrature Method,"In this article, a numerical simulation of two dimensional nonlinear
+sine-Gordon equation with Neumann boundary condition is obtained by using a
+composite scheme referred to as a modified cubic B spline differential
+quadrature method. The modified cubic B-spline serves as a basis function in
+the differential quadrature method to compute the weighting coefficients. Thus,
+the sine-Gordon equation is converted into a system of second order ordinary
+differential equations (ODEs). We solve the resulting system of ODEs by an
+optimal five stage and fourth-order strong stability preserving Runge Kutta
+scheme. Both damped and undamped cases are considered for the numerical
+simulation with Josephson current density function with value minus one. The
+computed results are found to be in good agreement with the exact solutions and
+other numerical results available in literature.",1410.0058v1
+2014-11-12,Semi-active Suspension Control using Modern Methodology: Comprehensive Comparison Study,"Semi-active suspensions have drawn particular attention due to their superior
+performance over the other types of suspensions. One of their advantages is
+that their damping coefficient can be controlled without the need for any
+external source of power. In this study, three control approaches are
+implemented on a quarter-car model using MATLAB/Simulink. The investigated
+control methodologies are Acceleration Driven Damper, Power Driven Damper, and
+H_infinity Robust Control. The three controllers are known as comfort-oriented
+approaches. H_infinity Robust Control is an advanced method that guarantees
+transient performance and rejects external disturbances. It is shown that
+H_infinity with the proposed modification, has the best performance although
+its relatively high cost of computation could be potentially considered as a
+drawback.",1411.3305v1
+2015-03-19,Quasinormal modes of test fields around regular black holes,"We study scalar, electromagnetic and gravitational test fields in the
+Hayward, Bardeen and Ay\'on-Beato-Garc\'ia regular black hole spacetimes and
+demonstrate that the test fields are stable in all these spacetimes. Using the
+sixth order WKB approximation of the linear ""axial"" perturbative scheme, we
+determine dependence of the quasinormal mode (QNM) frequencies on the
+characteristic parameters of the test fields and the spacetime charge
+parameters of the regular black holes. We give also the greybody factors,
+namely the transmission and reflection coefficients of scattered scalar,
+electromagnetic and gravitational waves. We show that damping of the QNMs in
+regular black hole spacetimes is suppressed in comparison to the case of
+Schwarzschild black holes, and increasing charge parameter of the regular black
+holes increases reflection and decreases transmission factor of incident waves
+for each of the test fields.",1503.05737v2
+2015-04-03,Role of attractive forces in determining the equilibrium structure and dynamics of simple liquids,"Molecular Dynamics simulations of a Lennard-Jones system with different range
+of attraction show that the attractive forces modify the radial distribution of
+the particles. For condensed liquids only, the forces within the the first
+coordination shell (FCS) are important, but for gases and moderate condensed
+fluids, even the attractive forces outside the FCS play a role. The changes in
+the distribution caused by neglecting the attractive forces, lead to a too high
+pressure. The weak long-range attractions damp the dynamics and the diffusion
+of the particles in gas-, super critical fluid- and in liquid states. The
+values of self-diffusion coefficients (SDC) agree qualitatively with a modified
+Cohen-Turnbull model. The SDC-s along the critical isotherm show no anomaly at
+the critical point in agreement with experimental data.",1504.00809v1
+2015-06-08,Another derivation of generalized Langevin equations,"The formal derivation of Langevin equations (and, equivalently Fokker-Planck
+equations) with projection operator techniques of Mori, Zwanzig, Kawasaki and
+others apparently not has widely found its way into textbooks. It has been
+reproduced dozens of times on the fly with many references to the literature
+and without adding much substantially new. Here we follow the tradition, but
+strive to produce a self-contained text. Furthermore, we address questions that
+naturally arise in the derivation. Among other things the meaning of the
+divergence of the Poisson brackets is explained, and the role of nonlinear
+damping coefficients is clarified. The derivation relies on classical
+mechanics, and encompasses everything one can construct from point particles
+and potentials: solids, liquids, liquid crystals, conductors, polymers, systems
+with spin-like degrees of freedom ... Einstein relations and Onsager
+reciprocity relations come for free.",1506.02650v2
+2015-06-09,Sensitivity analysis for shape optimization of a focusing acoustic lens in lithotripsy,"We are interested in shape sensitivity analysis for an optimization problem
+arising in medical applications of high intensity focused ultrasound. The goal
+is to find the optimal shape of a focusing acoustic lens so that the desired
+acoustic pressure at a kidney stone is achieved. Coupling of the silicone
+acoustic lens and nonlinearly acoustic fluid region is modeled by the
+Westervelt equation with nonlinear strong damping and piecewise constant
+coefficients. We follow the variational approach to calculating the shape
+derivative of the cost functional which does not require computing the shape
+derivative of the state variable; however assumptions of certain spatial
+regularity of the primal and the adjoint state are needed to obtain the
+derivative, in particular for its strong form according to the
+Delfour-Hadamard-Zol\' esio Structure Theorem.",1506.02781v1
+2015-06-26,Dimer with gain and loss: Integrability and $\mathcal{PT}$-symmetry restoration,"A $\mathcal{PT}$-symmetric nonlinear Schr\""odinger dimer is a two-site
+discrete nonlinear Schr\""odinger equation with one site losing and the other
+one gaining energy at the same rate. In this paper, two four-parameter families
+of cubic $\mathcal{PT}$-symmetric dimers are constructed as gain-loss
+extensions of their conservative, Hamiltonian, counterparts. We prove that all
+these damped-driven equations define completely integrable Hamiltonian systems.
+The second aim of our study is to identify nonlinearities that give rise to the
+spontaneous $\mathcal{PT}$-symmetry restoration. When the symmetry of the
+underlying linear dimer is broken and an unstable small perturbation starts to
+grow, the nonlinear coupling of the required type diverts progressively large
+amounts of energy from the gaining to the losing site. As a result, the
+exponential growth is saturated and all trajectories remain trapped in a finite
+part of the phase space regardless of the value of the gain-loss coefficient.",1506.08229v2
+2015-07-09,Background field method in the gradient flow,"In perturbative consideration of the Yang--Mills gradient flow, it is useful
+to introduce a gauge non-covariant term (""gauge-fixing term"") to the flow
+equation that gives rise to a Gaussian damping factor also for gauge degrees of
+freedom. In the present paper, we consider a modified form of the gauge-fixing
+term that manifestly preserves covariance under the background gauge
+transformation. It is shown that our gauge-fixing term does not affect
+gauge-invariant quantities as the conventional gauge-fixing term. The
+formulation thus allows a background gauge covariant perturbative expansion of
+the flow equation that provides, in particular, a very efficient computational
+method of expansion coefficients in the small flow time expansion. The
+formulation can be generalized to systems containing fermions.",1507.02360v3
+2015-07-16,Fast Convergence of an Inertial Gradient-like System with Vanishing Viscosity,"In a real Hilbert space $\mathcal H$, we study the fast convergence
+properties as $t \to + \infty$ of the trajectories of the second-order
+evolution equation $$ \ddot{x}(t) + \frac{\alpha}{t} \dot{x}(t) + \nabla \Phi
+(x(t)) = 0, $$ where $\nabla \Phi$ is the gradient of a convex continuously
+differentiable function $\Phi : \mathcal H \rightarrow \mathbb R$, and $\alpha$
+is a positive parameter. In this inertial system, the viscous damping
+coefficient $\frac{\alpha}{t}$ vanishes asymptotically in a moderate way. For
+$\alpha > 3$, we show that any trajectory converges weakly to a minimizer of
+$\Phi$, just assuming that the set of minimizers is nonempty. The strong
+convergence is established in various practical situations. These results
+complement the $\mathcal O(t^{-2})$ rate of convergence for the values obtained
+by Su, Boyd and Cand\`es. Time discretization of this system, and some of its
+variants, provides new fast converging algorithms, expanding the field of rapid
+methods for structured convex minimization introduced by Nesterov, and further
+developed by Beck and Teboulle. This study also complements recent advances due
+to Chambolle and Dossal.",1507.04782v1
+2015-07-29,"Gravitational, shear and matter waves in Kantowski-Sachs cosmologies","A general treatment of vorticity-free, perfect fluid perturbations of
+Kantowski-Sachs models with a positive cosmological constant are considered
+within the framework of the 1+1+2 covariant decomposition of spacetime. The
+dynamics is encompassed in six evolution equations for six harmonic
+coefficients, describing gravito-magnetic, kinematic and matter perturbations,
+while a set of algebraic expressions determine the rest of the variables. The
+six equations further decouple into a set of four equations sourced by the
+perfect fluid, representing forced oscillations and two uncoupled damped
+oscillator equations.
+  The two gravitational degrees of freedom are represented by pairs of
+gravito-magnetic perturbations. In contrast with the Friedmann case one of them
+is coupled to the matter density perturbations, becoming decoupled only in the
+geometrical optics limit. In this approximation, the even and odd tensorial
+perturbations of the Weyl tensor evolve as gravitational waves on the
+anisotropic Kantowski-Sachs background, while the modes describing the shear
+and the matter density gradient are out of phase dephased by $\pi /2$ and share
+the same speed of sound.",1507.08300v2
+2015-08-14,Reactive collisions of polar molecules in quasi-two-dimensional traps,"We investigate collisions of polar molecules in quasi-2D traps in the
+presence of an external electric field perpendicular to the collision plane. We
+use the quantum-defect model characterized by two dimensionless parameters: $y$
+and $s$. The first of them is related to the probability of the reaction at
+short distances, whereas the latter one defines the wave function phase at
+short distances. For $y$ close to unity we obtain universal collision rates
+determined by the quantum reflection process from the long-range part of the
+interaction potential that depends only on the van der Waals coefficient,
+dipole-dipole interaction and the trap frequency. For small short-range
+reaction probabilities collision rates are highly nonuniversal and trap induced
+shape resonances are visible. For high dipole moments we observe the damping of
+reactive collisions, which can stabilize the ultracold gas of polar molecules.
+The calculations were performed with help of multichannel wave funcion
+propagation by imposing short-range boundary condition derived from the
+quantum-defect model.",1508.03443v1
+2015-11-06,Curvature and torsion effects in the spin-current driven domain wall motion,"The domain wall motion along a helix-shaped nanowire is studied for the case
+of spin-current driving via Bazaliy-Zhang-Li mechanism. The analysis is based
+on collective variable approach. Two new effects are ascertained: (i) the
+curvature results in appearance of the Walker limit for a uniaxial wire, (ii)
+the torsion results in effective shift of the nonadiabatic spin torque
+parameter $\beta$. The latter effect changes considerably the domain wall
+velocity and can result in negative domain wall mobility. This effect can be
+also used for an experimental determination of the nonadiabatic parameter
+$\beta$ and damping coefficient $\alpha$.",1511.02193v1
+2015-11-15,Fluid friction and wall viscosity of the 1D blood flow model,"We study the behavior of the pulse waves of water into a flexible tube for
+application to blood flow simulations. In pulse waves both fluid friction and
+wall viscosity are damping factors, and difficult to evaluate separately. In
+this paper, the coefficients of fluid friction and wall viscosity are estimated
+by fitting a nonlinear 1D flow model to experimental data. In the experimental
+setup, a distensible tube is connected to a piston pump at one end and closed
+at another end. The pressure and wall displacements are measured
+simultaneously. A good agreement between model predictions and experiments was
+achieved. For amplitude decrease, the effect of wall viscosity on the pulse
+wave has been shown as important as that of fluid viscosity.",1511.04729v1
+2016-01-10,Classic Calculations of Static Properties of the Nucleons reexamined,"Classic calculations of the magnetic moments mu_p and mu_n of the nucleons
+using the traditional exponential kernel show instability with respect to
+variations of the Borel mass as well as arbitrariness with respect to the
+choice of the onset of perturbative QCD. The use of a polynomial kernel, the
+coefficients of which are determined by the masses of the nucleon resonances
+stabilizes the calculation and provides much better damping of the unknown
+contribution of the nucleon continuum. The method is also applied to the
+evaluation of the coupling gA of proton to the axial current and to the strong
+part of the neutron-proton mass difference Delta M_np. All these quantities
+depend sensitively on the value of the 4-quark condensate < 0 | qqqq | 0 > and
+the value < 0 | qqqq | 0 > ~ 1.5< 0 | qq | 0 >^2 reproduces the experimental
+results.",1601.02247v2
+2016-01-28,Dynamic system classifier,"Stochastic differential equations describe well many physical, biological and
+sociological systems, despite the simplification often made in their
+derivation. Here the usage of simple stochastic differential equations to
+characterize and classify complex dynamical systems is proposed within a
+Bayesian framework. To this end, we develop a dynamic system classifier (DSC).
+The DSC first abstracts training data of a system in terms of time dependent
+coefficients of the descriptive stochastic differential equation. Thereby the
+DSC identifies unique correlation structures within the training data. For
+definiteness we restrict the presentation of DSC to oscillation processes with
+a time dependent frequency {\omega}(t) and damping factor {\gamma}(t). Although
+real systems might be more complex, this simple oscillator captures many
+characteristic features. The {\omega} and {\gamma} timelines represent the
+abstract system characterization and permit the construction of efficient
+signal classifiers. Numerical experiments show that such classifiers perform
+well even in the low signal-to-noise regime.",1601.07901v2
+2016-05-11,Electromagnetic properties of a double layer graphene system with electron-hole pairing,"We study electromagnetic properties of a double layer graphene system in
+which electrons from one layer are coupled with holes from the other layer. The
+gauge invariant linear response functions are obtained. The frequency
+dependences of the transmission, reflection and absorption coefficients are
+computed. We predict a peak in the reflection and absorption at the frequency
+equals to the gap in the quasiparticle spectrum. It is shown that the
+electron-hole pairing results in an essential modification of the spectrum of
+surface TM plasmons. We find that the optical TM mode splits into a low
+frequency undamped branch and a high frequency damped branch. At zero
+temperature the lower branch disappears. It is established that the pairing
+does not influence the acoustic TM mode. It is also shown that the pairing
+opens the frequency window in the subgap range for the surface TE wave.",1605.03307v1
+2016-08-02,Nonperturbative quasi-classical theory of the nonlinear electrodynamic response of graphene,"An electromagnetic response of a single graphene layer to a uniform,
+arbitrarily strong electric field $E(t)$ is calculated by solving the kinetic
+Boltzmann equation within the relaxation-time approximation. The theory is
+valid at low (microwave, terahertz, infrared) frequencies satisfying the
+condition $\hbar\omega\lesssim 2E_F$, where $E_F$ is the Fermi energy. We
+investigate the saturable absorption and higher harmonics generation effects,
+as well as the transmission, reflection and absorption of radiation incident on
+the graphene layer, as a function of the frequency and power of the incident
+radiation and of the ratio of the radiative to scattering damping rates. We
+show that the optical bistability effect, predicted in Phys. Rev. B 90, 125425
+(2014) on the basis of a perturbative approach, disappears when the problem is
+solved exactly. We show that, under the action of a high-power radiation
+($\gtrsim 100$ kW/cm$^2$) both the reflection and absorption coefficients
+strongly decrease and the layer becomes transparent.",1608.00877v2
+2016-09-23,Underdamped scaled Brownian motion: (non-)existence of the overdamped limit in anomalous diffusion,"It is quite generally assumed that the overdamped Langevin equation provides
+a quantitative description of the dynamics of a classical Brownian particle in
+the long time limit. We establish and investigate a paradigm anomalous
+diffusion process governed by an underdamped Langevin equation with an explicit
+time dependence of the system temperature and thus the diffusion and damping
+coefficients. We show that for this underdamped scaled Brownian motion (UDSBM)
+the overdamped limit fails to describe the long time behaviour of the system
+and may practically even not exist at all for a certain range of the parameter
+values. Thus persistent inertial effects play a non-negligible role even at
+significantly long times. From this study a general questions on the
+applicability of the overdamped limit to describe the long time motion of an
+anomalously diffusing particle arises, with profound consequences for the
+relevance of overdamped anomalous diffusion models. We elucidate our results in
+view of analytical and simulations results for the anomalous diffusion of
+particles in free cooling granular gases.",1609.07250v1
+2016-11-25,Random and quasi-coherent aspects in particle motion and their effects on transport and turbulence evolution,"The quasi-coherent effects in two-dimensional incompressible turbulence are
+analyzed starting from the test particle trajectories. They can acquire
+coherent aspects when the stochastic potential has slow time variation and the
+motion is not strongly perturbed. The trajectories are, in these conditions,
+random sequences of large jumps and trapping or eddying events. Trapping
+determines quasi-coherent trajectory structures, which have a micro-confinement
+effect that is reflected in the transport coefficients. They determine
+non-Gaussian statistics and flows associated to an average velocity. Trajectory
+structures also influence the test modes on turbulent plasmas. Nonlinear
+damping and generation of zonal flow modes is found in drift turbulence in
+uniform magnetic field. The coupling of test particle and test mode studies
+permitted to evaluate the self-consistent evolution of the drift turbulence in
+an iterated approach. The results show an important nonlinear effect of ion
+diffusion, which can prevent the transition to the nonlinear regime at small
+drive of the instability. At larger drive, quasi-coherent trajectory structures
+appear and they have complex effects on turbulence.",1611.08521v1
+2017-01-07,A quantitative description of Nernst effect in high-temperature superconductors,"A quantitative vortex-fluid model for flux-flow resistivity $\rho$ and Nernst
+signal $e_N$ in high-temperature superconductors (HTSC) is proposed. Two kinds
+of vortices, magnetic and thermal, are considered, and the damping viscosity
+$\eta$ is modeled by extending the Bardeen-Stephen model to include the
+contributions of flux pinning at low temperature and in weak magnetic fields,
+and vortex-vortex collisions in strong magnetic fields. Remarkably accurate
+descriptions for both Nernst signal of six samples and flux flow resistivity
+are achieved over a wide range of temperature $T$ and magnetic field $B$. A
+discrepancy of three orders of magnitude between data and Anderson's model of
+Nernst signal is pointed out and revised using experimental values of $\eta$
+from magnetoresistance. Furthermore, a two-step procedure is developed to
+reliably extract, from the Nernst signal, a set of physical parameters
+characterizing the vortex dynamics, which yields predictions of local
+superfluid density $n_s$, the Kosterlitz coefficient $b$ of thermal vortices,
+and upper critical field and temperature. Application of the model and
+systematic measurement of relevant physical quantities from Nernst signal in
+other HTSC samples are discussed.",1701.01832v1
+2017-01-23,Understanding stability diagram of perpendicular magnetic tunnel junctions,"Perpendicular magnetic tunnel junctions (MTJ) with a bottom pinned reference
+layer and a composite free layer (FL) are investigated. Different thicknesses
+of the FL were tested to obtain an optimal balance between tunneling
+magnetoresistance (TMR) ratio and perpendicular magnetic anisotropy. After
+annealing at 400 $^\circ$C, the TMR ratio for 1.5 nm thick CoFeB sublayer
+reached 180 % at room temperature and 280 % at 20 K with an MgO tunnel barrier
+thickness corresponding to the resistance area product RA = 10
+Ohm$\mathrm{\mu}$m$^2$. The voltage vs. magnetic field stability diagrams
+measured in pillar-shaped MTJs with 130 nm diameter indicate the competition
+between spin transfer torque (STT), voltage controlled magnetic anisotropy
+(VCMA) and temperature effects in the switching process. An extended stability
+phase diagram model that takes into account all three parameters and the
+effective damping measured independently using broadband ferromagnetic
+resonance technique enabled the determination of both STT and VCMA coefficients
+that are responsible for the FL magnetization switching.",1701.06411v1
+2017-01-27,Evaluating the Friction of Rotary Joints in Molecular Machines,"A computationally-efficient method for evaluating friction in molecular
+rotary bearings is presented. This method estimates drag from fluctuations in
+molecular dynamics simulations via the fluctuation-dissipation theorem. This is
+effective even for simulation times short compared to a bearing's energy
+damping time and for rotation speeds comparable to or below typical thermal
+values. We apply this method to two molecular rotary bearings of similar size
+at 300K: previously studied nested (9,9)/(14,14) double-walled carbon nanotubes
+and a hypothetical rotary joint consisting of single acetylenic bonds in a
+rigid diamondoid housing. The acetylenic joint has a rotational frictional drag
+coefficient of $2 \times 10^{-35}\,\mbox{kg m${}^2$/s}$. The friction for the
+nested nanotubes is 120 times larger, comparable to values reported by previous
+studies. This fluctuation-based method could evaluate dissipation in a variety
+of molecular systems with similarly rigid and symmetric bearings.",1701.08202v2
+2017-04-01,Homogenization for a Class of Generalized Langevin Equations with an Application to Thermophoresis,"We study a class of systems whose dynamics are described by generalized
+Langevin equations with state-dependent coefficients. We find that in the
+limit, in which all the characteristic time scales vanish at the same rate, the
+position variable of the system converges to a homogenized process, described
+by an equation containing additional drift terms induced by the noise. The
+convergence results are obtained using the main result in
+\cite{hottovy2015smoluchowski}, whose version is proven here under a weaker
+spectral assumption on the damping matrix. We apply our results to study
+thermophoresis of a Brownian particle in a non-equilibrium heat bath.",1704.00134v2
+2017-04-03,Parametrization of the Tkatchenko-Scheffler dispersion correction scheme for popular exchange-correlation density functionals: effect on the description of liquid water,"We present a list of optimized damping range parameters $s_R$ to be used with
+the Tkatchenko-Scheffler van der Waals dispersion-correction scheme [Phys. Rev.
+Lett. 102, 073005 (2009)]. The optimal $s_R$ are obtained for seven popular
+generalized-gradient approximation exchange-correlation density functionals:
+PBE, RPBE, revPBE, PBEsol, BLYP, AM05 and PW91. The optimization is carried out
+in the standard way by minimizing the mean absolute error of the S22 test set,
+where the reference interaction energies are taken from coupled-cluster
+calculations. With the optimized range parameters, we assess the impact of van
+der Waals corrections on the ability of these functionals to accurately
+describe structural and thermodynamic properties of liquid water: radial
+distribution functions, self-diffusion coefficients and standard molar
+entropies.",1704.00761v2
+2017-04-13,Stochastic Gradient Descent as Approximate Bayesian Inference,"Stochastic Gradient Descent with a constant learning rate (constant SGD)
+simulates a Markov chain with a stationary distribution. With this perspective,
+we derive several new results. (1) We show that constant SGD can be used as an
+approximate Bayesian posterior inference algorithm. Specifically, we show how
+to adjust the tuning parameters of constant SGD to best match the stationary
+distribution to a posterior, minimizing the Kullback-Leibler divergence between
+these two distributions. (2) We demonstrate that constant SGD gives rise to a
+new variational EM algorithm that optimizes hyperparameters in complex
+probabilistic models. (3) We also propose SGD with momentum for sampling and
+show how to adjust the damping coefficient accordingly. (4) We analyze MCMC
+algorithms. For Langevin Dynamics and Stochastic Gradient Fisher Scoring, we
+quantify the approximation errors due to finite learning rates. Finally (5), we
+use the stochastic process perspective to give a short proof of why Polyak
+averaging is optimal. Based on this idea, we propose a scalable approximate
+MCMC algorithm, the Averaged Stochastic Gradient Sampler.",1704.04289v2
+2017-05-19,Phenomenology of light- and strange-quark simultaneous production at high energies,"This letter presents an extension of EPL116(2017)62001 to light- and
+strange-quark nonequilibrium chemical phase-space occupancy factors
+($\gamma_{q,s}$). The resulting damped trigonometric functionalities relating
+$\gamma_{q,s}$ to the nucleon-nucleon center-of-mass energies $(\sqrt{s_{NN}})$
+looks very similar except different coefficients. The phenomenology of the
+resulting $\gamma_{q,s}(\sqrt{s_{NN}})$ describes a rapid decrease at
+$\sqrt{s_{NN}}\lesssim7~$GeV followed by a faster increase up to $\sim20~$GeV.
+Then, both $\gamma_{q,s}$ become nonsensitive to $\sqrt{s_{NN}}$. Although
+these differ from $\gamma_{s}(\sqrt{s_{NN}})$ obtained at
+$\gamma_q(\sqrt{s_{NN}})=1$, various particle ratios including
+$\mathrm{K}^+/\pi^+$, $\mathrm{K}^-/\pi^-$, $\mathrm{\Lambda}/\pi^-$,
+$\bar{\mathrm{\Lambda}}/\pi^-$, $\mathrm{\Xi}^+/\pi^+$, and
+$\mathrm{\Omega}/\pi^-$, can well be reproduced, as well. We conclude that
+$\gamma_{q,s}(\sqrt{s_{NN}})$ should be instead determined from fits of various
+particle yields and ratios but not merely from fits to the particle ratio
+$\mathrm{K}^+/\pi^+$.",1705.06961v1
+2017-11-08,An Extended Kalman Filter Enhanced Hilbert-Huang Transform in Oscillation Detection,"Hilbert-Huang transform (HHT) has drawn great attention in power system
+analysis due to its capability to deal with dynamic signal and provide
+instantaneous characteristics such as frequency, damping, and amplitudes.
+However, its shortcomings, including mode mixing and end effects, are as
+significant as its advantages. A preliminary result of an extended Kalman
+filter (EKF) method to enhance HHT and hopefully to overcome these
+disadvantages is presented in this paper. The proposal first removes dynamic DC
+components in signals using empirical mode decomposition. Then an EKF model is
+applied to extract instant coefficients. Numerical results using simulated and
+real-world low-frequency oscillation data suggest the proposal can help to
+overcome the mode mixing and end effects with a properly chosen number of
+modes.",1711.04644v1
+2017-11-15,Probing Split-Ring Resonator Permeabilities with Loop-Gap Resonators,"A method is proposed to experimentally determine the effective complex
+permeability of split-ring resonator (SRR) arrays used in the design of
+metamaterials at microwave frequencies. We analyze the microwave response of a
+loop-gap resonator (LGR) whose bore has been partially loaded with one or more
+SRRs. Our analysis reveals that the resonance frequency, magnetic plasma
+frequency, and damping constant of the effective permeability of the SRR array
+can be extracted from fits to the reflection coefficient (S11) of an
+inductively-coupled LGR. We propose LGR designs that would allow both a
+one-dimensional array of SRRs and small three-dimensional arrays of SRRs to be
+characterized. Finally, we demonstrate the method using a toroidal LGR loaded
+with a single extended SRR of length z.",1711.05819v1
+2017-12-01,Some Optimizations on Detecting Gravitational Wave Using Convolutional Neural Network,"This work investigates the problem of detecting gravitational wave (GW)
+events based on simulated damped sinusoid signals contaminated with white
+Gaussian noise. It is treated as a classification problem with one class for
+the interesting events. The proposed scheme consists of the following two
+successive steps: decomposing the data using a wavelet packet, representing the
+GW signal and noise using the derived decomposition coefficients; and
+determining the existence of any GW event using a convolutional neural network
+(CNN) with a logistic regression output layer. The characteristics of this work
+is its comprehensive investigations on CNN structure, detection window width,
+data resolution, wavelet packet decomposition and detection window overlap
+scheme. Extensive simulation experiments show excellent performances for
+reliable detection of signals with a range of GW model parameters and
+signal-to-noise ratios. While we use a simple waveform model in this study, we
+expect the method to be particularly valuable when the potential GW shapes are
+too complex to be characterized with a template bank.",1712.00356v2
+2018-02-12,Dynamics of a magnetic skyrmionium driven by spin waves,"The magnetic skyrmionium is a skyrmion-like structure but carries a zero net
+skyrmion number, which can be used as a building block for non-volatile
+information processing devices. Here, we study the dynamics of a magnetic
+skyrmionium driven by propagating spin waves. It is found that the skyrmionium
+can be effectively driven into motion by spin waves showing tiny skyrmion Hall
+effect, of which the mobility is much better than that of the skyrmion at the
+same condition. We also show that the skyrmionium mobility depends on the
+nanotrack width and damping coefficient, and can be controlled by an external
+out-of-plane magnetic field. Besides, we demonstrate the skyrmionium motion
+driven by spin waves is inertial. Our results indicate that the skyrmionium is
+a promising building block for building spin-wave spintronic devices.",1802.03868v2
+2018-02-16,Articulatory information and Multiview Features for Large Vocabulary Continuous Speech Recognition,"This paper explores the use of multi-view features and their discriminative
+transforms in a convolutional deep neural network (CNN) architecture for a
+continuous large vocabulary speech recognition task. Mel-filterbank energies
+and perceptually motivated forced damped oscillator coefficient (DOC) features
+are used after feature-space maximum-likelihood linear regression (fMLLR)
+transforms, which are combined and fed as a multi-view feature to a single CNN
+acoustic model. Use of multi-view feature representation demonstrated
+significant reduction in word error rates (WERs) compared to the use of
+individual features by themselves. In addition, when articulatory information
+was used as an additional input to a fused deep neural network (DNN) and CNN
+acoustic model, it was found to demonstrate further reduction in WER for the
+Switchboard subset and the CallHome subset (containing partly non-native
+accented speech) of the NIST 2000 conversational telephone speech test set,
+reducing the error rate by 12% relative to the baseline in both cases. This
+work shows that multi-view features in association with articulatory
+information can improve speech recognition robustness to spontaneous and
+non-native speech.",1802.05853v1
+2018-02-26,A magnetic resonance in high-frequency viscosity of two-dimensional electrons,"Two-dimensional (2D) electrons in high-quality nanostructures at low
+temperatures can form a viscous fluid. We develop a theory of high-frequency
+magnetotransport in such fluid. The time dispersion of viscosity should be
+taken into account at the frequencies about and above the rate of
+electron-electron collisions. We show that the shear viscosity coefficients as
+functions of magnetic field and frequency have the only resonance at the
+frequency equal to the doubled cyclotron frequency. We demonstrate that such
+resonance manifests itself in the plasmon damping. Apparently, the predicted
+resonance is also responsible for the peaks and features in photoresistance and
+photovoltage, recently observed on the best-quality GaAs quantum wells. The
+last fact should considered as an important evidence of forming a viscous
+electron fluid in such structures.",1802.09179v3
+2018-03-14,Langevin equation in systems with also negative temperatures,"We discuss how to derive a Langevin equation (LE) in non standard systems,
+i.e. when the kinetic part of the Hamiltonian is not the usual quadratic
+function. This generalization allows to consider also cases with negative
+absolute temperature. We first give some phenomenological arguments suggesting
+the shape of the viscous drift, replacing the usual linear viscous damping, and
+its relation with the diffusion coefficient modulating the white noise term. As
+a second step, we implement a procedure to reconstruct the drift and the
+diffusion term of the LE from the time-series of the momentum of a heavy
+particle embedded in a large Hamiltonian system. The results of our
+reconstruction are in good agreement with the phenomenological arguments.
+Applying the method to systems with negative temperature, we can observe that
+also in this case there is a suitable Langevin equation, obtained with a
+precise protocol, able to reproduce in a proper way the statistical features of
+the slow variables. In other words, even in this context, systems with negative
+temperature do not show any pathology.",1803.05317v2
+2018-04-07,Chemotaxis effect vs logistic damping on boundedness in the 2-D minimal Keller-Segel model,"In this paper, we study chemotaxis effect vs logistic dampening on
+boundedness for the two-dimensional minimal Keller-Segel model with logistic
+source in a 2-D smooth and bounded domain. It is well-known that this model
+allows only for global and uniform-in-time bounded solutions for any
+chemotactic strength and logistic dampening. Here, we carefully employ a simple
+and new method to regain its boundedness and, with particular attention to how
+boundedness depends qualitatively on the coefficient of chemotactic strength
+and logistic dampening rate. Up to a scaling constant depending only on initial
+data and the domain, we provide explicit upper bounds for the the solution
+components of the corresponding initial-boundary value problem. This
+qualitative boundedness results seems to be the first result in the regard.",1804.02501v1
+2018-05-07,"Lewis-Riesenfeld quantization and SU(1,1) coherent states for 2D damped harmonic oscillator","In this paper we study a two-dimensional [2D] rotationally symmetric harmonic
+oscillator with time-dependent frictional force. At the classical level, we
+solve the equations of motion for a particular case of the time-dependent
+coefficient of friction. At the quantum level, we use the Lewis-Riesenfeld
+procedure of invariants to construct exact solutions for the corresponding
+time-dependent Schr\""{o}dinger equations. The eigenfunctions obtained are in
+terms of the generalized Laguerre polynomials. By mean of the solutions we
+verify a generalization version of the Heisenberg's uncertainty relation and
+derive the generators of the $su(1,1)$ Lie algebra. Based on these generators,
+we construct the coherent states $\grave{\textrm{a}}$ la Barut-Girardello and
+$\grave{\textrm{a}}$ la Perelomov and respectively study their properties.",1805.02484v2
+2018-05-16,Numerical analysis of the weakly nonlinear Boussinesq system with a freely moving body on the bottom,"In this study, the numerical analysis of a specific fluid-solid interaction
+problem is detailed. The weakly nonlinear Boussinesq system is considered with
+the addition of a solid object lying on the flat bottom, allowed to move
+horizontally under the pressure forces created by the waves. We present an
+accurate finite difference scheme for this physical model, finely tuned to
+preserve important features of the original coupled system: nonlinear effects
+for the waves, energy dissipation due to the frictional movement of the solid.
+The moving bottom case is compared with a system where the same object is fixed
+to the bottom in order to observe the qualitative and quantitative differences
+in wave transformation. In particular a loss of wave amplitude is observed. The
+influence of the friction on the whole system is also measured, indicating
+differences for small and large coefficients of friction. Overall, hydrodynamic
+damping effects reminiscent to the dead-water phenomenon can be established.",1805.07216v1
+2018-05-21,"Squeezed in three dimensions, moving in two: Hydrodynamic theory of 3D incompressible easy-plane polar active fluids","We study the hydrodynamic behavior of three dimensional (3D) incompressible
+collections of self-propelled entities in contact with a momentum sink in a
+state with non-zero average velocity, hereafter called 3D easy-plane
+incompressible polar active fluids. We show that the hydrodynamic model for
+this system belongs to the same universality class as that of an equilibrium
+system, namely a special 3D anisotropic magnet. The latter can be further
+mapped onto yet another equilibrium system, a DNA-lipid mixture in the sliding
+columnar phase. Through these connections we find a divergent renormalization
+of the damping coefficients in 3D easy-plane incompressible polar active
+fluids, and obtain their equal-time velocity correlation functions.",1805.07930v1
+2018-06-12,Complex magnetism and non-Fermi liquid state in the vicinity of the quantum critical point in the CeCo$_{1-x}$Fe$_x$Ge$_3$ series,"We report extensive studies on the CeCo$_{1-x}$Fe$_{x}$Ge$_3$ alloys, which
+show quantum critical point (QCP) due to damping the antiferromagnetic order in
+CeCoGe$_3$ down to 0 K by doping with the paramagnetic CeFeGe$_3$ compound. The
+presence of QCP is confirmed by detecting the non-Fermi liquid behavior (NFL)
+using a wide range of the experimental methods: magnetic susceptibility,
+specific heat, electrical resistivity, magnetoresistance, and thermoelectric
+power. In the case of the thermoelectric power we find a clear enhancement of
+the Seebeck coefficient for $x$ around 0.6, i.e. in the neighborhood of QCP.
+Finally, the different complementary studies enabled construction of the
+complex magnetic phase diagram for the CeCo$_{1-x}$Fe$_{x}$Ge$_3$ system,
+including the energy scale imposed by the crystal electric field splitting of
+the Ce ground state.",1806.04656v1
+2018-08-21,Position Sensor-less and Adaptive Speed Design for Controlling Brush-less DC Motor Drives,"This paper proposes a method for direct torque control of Brushless DC (BLDC)
+motors. Evaluating the trapezium of back-EMF is needed, and is done via a
+sliding mode observer employing just one measurement of stator current. The
+effect of the proposed estimation algorithm is reducing the impact of switching
+noise and consequently eliminating the required filter. Furthermore, to
+overcome the uncertainties related to BLDC motors, Recursive Least Square (RLS)
+is regarded as a real-time estimator of inertia and viscous damping
+coefficients of the BLDC motor. By substituting the estimated load torque in
+mechanical dynamic equations, the rotor speed can be calculated. Also, to
+increase the robustness and decrease the rise time of the system, Modified
+Model Reference Adaptive System (MMRAS) is applied in order to design a new
+speed controller. Simulation results confirm the validity of this recommended
+method.",1808.06768v1
+2018-09-28,Unifying averaged dynamics of the Fokker-Planck equation for Paul traps,"Collective dynamics of a collisional plasma in a Paul trap is governed by the
+Fokker-Planck equation, which is usually assumed to lead to a unique asymptotic
+time-periodic solution irrespective of the initial plasma distribution. This
+uniqueness is, however, hard to prove in general due to analytical
+difficulties. For the case of small damping and diffusion coefficients, we
+apply averaging theory to a special solution to this problem, and show that the
+averaged dynamics can be represented by a remarkably simple 2D phase portrait,
+which is independent of the applied rf field amplitude. In particular, in the
+2D phase portrait, we have two regions of initial conditions. From one region,
+all solutions are unbounded. From the other region, all solutions go to a
+stable fixed point, which represents a unique time-periodic solution of the
+plasma distribution function, and the boundary between these two is a parabola.",1809.10952v2
+2018-10-29,Three Mechanisms of Weight Decay Regularization,"Weight decay is one of the standard tricks in the neural network toolbox, but
+the reasons for its regularization effect are poorly understood, and recent
+results have cast doubt on the traditional interpretation in terms of $L_2$
+regularization. Literal weight decay has been shown to outperform $L_2$
+regularization for optimizers for which they differ. We empirically investigate
+weight decay for three optimization algorithms (SGD, Adam, and K-FAC) and a
+variety of network architectures. We identify three distinct mechanisms by
+which weight decay exerts a regularization effect, depending on the particular
+optimization algorithm and architecture: (1) increasing the effective learning
+rate, (2) approximately regularizing the input-output Jacobian norm, and (3)
+reducing the effective damping coefficient for second-order optimization. Our
+results provide insight into how to improve the regularization of neural
+networks.",1810.12281v1
+2018-11-05,Logarithmic estimates for continuity equations,"The aim of this short note is twofold. First, we give a sketch of the proof
+of a recent result proved by the authors in the paper [Colombo, Crippa, and
+Spirito, Calc. Var. Partial Differential Equations 2015] concerning existence
+and uniqueness of renormalized solutions of continuity equations with unbounded
+damping coefficient. Second, we show how the ideas in [Colombo, Crippa, and
+Spirito, Calc. Var. Partial Differential Equations 2015] can be used to provide
+an alternative proof of the result in [Clop, Jiang, Mateu, and Orobitg, Calc.
+Var. Partial Differential Equations 2016], [Desjardins, Comm. Partial Diff. Eq.
+1996], and [Mucha, J. Differential Equations 2010] where the usual requirement
+of boundedness of the divergence of the vector field has been relaxed to
+various settings of exponentially integrable functions.",1811.02463v1
+2018-12-20,Edge modes and Fabry-Perot Plasmonic Resonances in anomalous-Hall Thin Films,"We study plasmon propagation on a metallic two-dimensional surface partially
+coated with a thin film of anomalous-Hall material. The resulting three
+regions, separated by two sharp interfaces, are characterised by different Hall
+conductivities but identical normal conductivities. A single bound mode is
+found, which can localise to either interface and has an asymmetric potential
+profile across the region. For propagating modes, we calculate the reflection
+and transmission coefficients through the magnetic region. We find Airy
+transmission patterns with sharp maxima and minima as a function of the plasmon
+incidence angle. The system therefore behaves as a high-quality filter.",1812.08798v2
+2019-01-01,Gravitational Waves in the Presence of Viscosity,"We analyze gravitational waves propagating in an isotropic cosmic fluid
+endowed with a bulk viscosity $\zeta$ and a shear viscosity $\eta$, assuming
+these coefficients to vary with fluid density $\rho$ as $\rho^\lambda$, with
+$\lambda=1/2$ favored by experimental evidence. We give the general governing
+equation for the gravitational waves, and focus thereafter on two examples. The
+first concerns waves in the very late universe, close to the Big Rip, where the
+fate of the comic fluid is dependent highly on the values of the parameters.
+Our second example considers the very early universe, the lepton era; the
+motivation for this choice being that the microscopical bulk viscosity as
+calculated from statistical mechanics is then at maximum. We find that the
+gravitational waves on such an underlying medium are damped, having a decay
+constant equal to the inverse of the conformal Hubble parameter. Our results
+turn out to be in good agreement with other viscosity-based approaches.",1901.00767v3
+2019-01-20,Fate of spin polarization in a relativistic fluid: An entropy-current analysis,"We derive relativistic hydrodynamic equations with a dynamical spin degree of
+freedom on the basis of an entropy-current analysis. The first and second laws
+of local thermodynamics constrain possible structures of the constitutive
+relations including a spin current and the antisymmetric part of the
+(canonical) energy-momentum tensor. Solving the obtained hydrodynamic equations
+within the linear-mode analysis, we find spin-diffusion modes, indicating that
+spin density is damped out after a characteristic time scale controlled by
+transport coefficients introduced in the antisymmetric part of the
+energy-momentum tensor in the entropy-current analysis. This is a consequence
+of mutual convertibility between spin and orbital angular momentum.",1901.06615v2
+2019-01-24,A priori error estimates for the finite element approximation of Westervelt's quasilinear acoustic wave equation,"We study the spatial discretization of Westervelt's quasilinear strongly
+damped wave equation by piecewise linear finite elements. Our approach employs
+the Banach fixed-point theorem combined with a priori analysis of a linear wave
+model with variable coefficients. Degeneracy of the semi-discrete Westervelt
+equation is avoided by relying on the inverse estimates for finite element
+functions and the stability and approximation properties of the interpolation
+operator. In this way, we obtain optimal convergence rates in $L^2$-based
+spatial norms for sufficiently small data and mesh size and an appropriate
+choice of initial approximations. Numerical experiments in a setting of a 1D
+channel as well as for a focused-ultrasound problem illustrate our theoretical
+findings.",1901.08510v3
+2019-02-26,Coulomb drag of excitons in Bose-Fermi mixtures,"We develop a microscopic theory of the Coulomb drag effect in a hybrid system
+consisting of spatially separated two-dimensional quantum gases of degenerate
+electrons and dipolar excitons. We consider both the normal-phase and
+condensate regimes of the exciton subsystem and investigate the cross-mobility
+of the system being the kinetic coefficient, which couples the static electric
+field applied to the electron layer with the particle density current (flux) in
+the exciton subsystem. We study the temperature dependence of the
+cross-mobility and its dependence on the interlayer separation. We show that
+exciton-exciton interaction plays a dramatic role. If the exciton gas is in the
+normal phase, then the screening of interlayer interaction by the exciton
+subsystem results in an exponential damping of the cross-mobility with the
+decrease of temperature, while at low temperatures, the interactions result in
+a robust bosonic transport due to the emergence of the Bogoliubov
+quasiparticles.",1902.09721v1
+2019-04-23,Generalized Moment Correction for Long-Ranged Electrostatics,"Describing long-ranged electrostatics using short-ranged pair potentials is
+appealing since the computational complexity scales linearly with the number of
+particles. The foundation of this approach is to mimic the long-ranged medium
+response by cancelling electric multipoles within a small cutoff sphere. We
+propose a rigorous and formally exact new method that cancels up to infinitely
+many multipole moments and is free of operational damping parameters often
+required in existing theories. Using molecular dynamics simulations of water
+with and without added salt, we discuss radial distribution functions,
+Kirkwood-Buff integrals, dielectrics, diffusion coefficients, and angular
+correlations in relation to existing electrostatic models. We find that the
+proposed method is an efficient and accurate alternative for handling
+long-ranged electrostatics as compared to Ewald summation schemes. The
+methodology and proposed parameterization is applicable also for dipole-dipole
+interactions.",1904.10335v2
+2019-06-02,Analytical prediction of logarithmic Rayleigh scattering in amorphous solids from tensorial heterogeneous elasticity with power-law disorder,"The damping or attenuation coefficient of sound waves in solids due to
+impurities scales with the wavevector to the fourth power, also known as
+Rayleigh scattering. In amorphous solids, Rayleigh scattering may be enhanced
+by a logarithmic factor although computer simulations offer conflicting
+conclusions regarding this enhancement and its microscopic origin. We present a
+tensorial replica field-theoretic derivation based on heterogeneous or
+fluctuating elasticity (HE), which shows that long-range (power-law) spatial
+correlations of the elastic constants, is the origin of the logarithmic
+enhancement to Rayleigh scattering of phonons in amorphous solids. We also
+consider the case of zero spatial fluctuations in the elastic constants, and of
+power-law decaying fluctuations in the internal stresses. Also in this case the
+logarithmic enhancement to the Rayleigh scattering law can be derived from the
+proposed tensorial HE framework.",1906.00372v3
+2019-05-31,Deterministic and stochastic damage detection via dynamic response analysis,"The paper proposes a method of damage detection in elastic materials, which
+is based on analyzing the time-dependent (dynamic) response of the material
+excited by an acoustic signal. A case study is presented consisting of
+experimental measurements and their mathematical analysis. The decisive
+parameters (wave speed and damping coefficient) of a mathematical model of the
+acoustic wave are calibrated by comparing the measurement data with the
+numerically evaluated exact solution predicted by the mathematical model. The
+calibration is done both deterministically by minimizing the square error over
+time and stochastically by a Bayesian approach, implemented through the
+Metropolis-Hastings algorithm. The resulting posterior distribution of the
+parameters can be used to construct a Bayesian test for damage.",1906.00797v2
+2019-07-21,Supersolutions for parabolic equations with unbounded diffusion and its applications to some classes of parabolic and hyperbolic equations,"This paper is concerned with supersolutions to parabolic equations of the
+form \begin{equation} \partial_t U (x,t)-D(x)\Delta U(x,t)=0, \quad (x,t)\in
+\mathbb{R}^N \times (0,\infty), \end{equation} where $D\in C(\mathbb{R}^N)$ is
+positive. Under the behavior of the diffusion coefficient $D$ with polynomial
+order at spatial infinity, a family of supersolutions with slowly decaying
+property at spatial infinity is provided. As a first application, weighted
+$L^2$ type decay estimates for the initial-boundary value problem of the
+corresponding parabolic equation are proved. The second application is the
+study of the exterior problem of wave equations with space-dependent damping
+terms. By using supersolutions provided above, energy estimates with polynomial
+weight and diffusion phenomena are shown.",1907.08992v1
+2019-08-11,A computational study of transient shear banding in soft jammed solids,"We have designed 3D numerical simulations of a soft spheres model, with size
+polidispersity and in athermal conditions, to study the transient shear banding
+that occurs during yielding of jammed soft solids. We analyze the effects of
+different types of drag coefficients used in the simulations and compare the
+results obtained using Lees-Edwards periodic boundary conditions with the case
+in which the same model solid is confined between two walls. The specific
+damping mechanism and the different boundary conditions indeed modify the load
+curves and the velocity profiles in the transient regime. Nevertheless, we find
+that the presence of a stress-overshoot and of a related transient banding
+phenomenon for large enough samples are a robust feature for overdamped
+systems, where their presence do not depend on the specific drag used and on
+the different boundary conditions.",1908.03943v1
+2019-09-10,Diffusion and memory effect in a stochastic processes and the correspondence to an information propagation in a social system,"A generalized Langevin equation is suggested to describe a system with
+memory($u(t,t') = \frac{1}{\Gamma (\nu )}(t - t')^\nu $) as well as with
+positive and negative damping. The equation can be transformed into the
+Fokker-Planck equation by using the Kramers-Moyal expansion. The solution of
+Fokker-Planck equation shows that velocity obeys a Gaussian distribution. The
+distribution curve will flatten as the memory parameter increases, which
+indicates that memory can enhance the randomness of the system. There are also
+some other memory effects behind this distribution, which can be characterized
+by calculating the transport coefficients, mean square displacement and
+correlation between the noise and space. These discussions can be paralleled to
+a social system to understand the propagation of social ideology caused by
+memory.",1909.04220v1
+2019-10-10,Mesoscopic theory for systems with competing interactions near a confining wall,"Mesoscopic theory for self-assembling systems near a planar confining surface
+is developed. Euler- Lagrange (EL) equations and the boundary conditions (BC)
+for the local volume fraction and the correlation function are derived from the
+DFT expression for the grand thermodynamic potential. Various levels of
+approximation can be considered for the obtained equations. The lowest-order
+nontrivial approximation (GM) resembles the Landau-Brazovskii type theory for a
+semiinfinite system. Unlike in the original phenomenological theory, however,
+all coefficients in our equations and BC are expressed in terms of the
+interaction potential and the thermodynamic state. Analytical solutions of the
+linearized equations in GM are presented and discussed on a general level and
+for a particular example of the double-Yukawa potential. We show exponentially
+damped oscillations of the volume fraction and the correlation function in the
+direction perpendicular to the confining surface. The correlations show
+oscillatory decay in directions parallel to this surface too, with the decay
+length increasing significantly when the system boundary is approached. The
+framework of our theory allows for a systematic improvement of the accuracy of
+the results.",1910.04474v2
+2019-11-11,Orbit-like trajectory of the vortex core in a magnetic nanodot,"In physics, conserved quantities are key to understanding and describing
+physical phenomena. These conserved quantities are related to Noether's theorem
+and the Lagrangian description both in classical mechanics and in field theory.
+In this article we have found the equation of the vortex core trajectory in
+terms of two conserved physical quantities, namely the energy, $E$, and a
+vector perpendicular to the orbit plane, $\vec{A} = -\vec{L} + \vec{G} \,
+|\vec{r}_c|^2/2$ where $\vec{G}$, $\vec{L}$ and $\vec{r}_c$ are the topological
+gyrovector, the angular momentum and the position of the vortex core,
+respectively. We find that in the absence of a dissipative term, for small
+deviations of the vortex core, the trajectory is bounded between two concentric
+circles. On the contrary, under the action of a dissipative term proportional
+to the damping coefficient, $\vec{A}$ is no longer conservative and the vortex
+core moves either towards the center or out of the cylinder, depending on the
+circularity of the magnetic vortex and the intensity of the magnetic field
+applied in the plane of the cylinder.",1911.04555v2
+2019-12-04,A high-order discontinuous Galerkin method for nonlinear sound waves,"We propose a high-order discontinuous Galerkin scheme for nonlinear acoustic
+waves on polytopic meshes. To model sound propagation with and without losses,
+we use Westervelt's nonlinear wave equation with and without strong damping.
+Challenges in the numerical analysis lie in handling the nonlinearity in the
+model, which involves the derivatives in time of the acoustic velocity
+potential, and in preventing the equation from degenerating. We rely in our
+approach on the Banach fixed-point theorem combined with a stability and
+convergence analysis of a linear wave equation with a variable coefficient in
+front of the second time derivative. By doing so, we derive an a priori error
+estimate for Westervelt's equation in a suitable energy norm for the polynomial
+degree $p \geq 2$. Numerical experiments carried out in two-dimensional
+settings illustrate the theoretical convergence results. In addition, we
+demonstrate efficiency of the method in a three-dimensional domain with varying
+medium parameters, where we use the discontinuous Galerkin approach in a hybrid
+way.",1912.02281v1
+2019-12-05,The blow up of solutions to semilinear wave equations on asymptotically Euclidean manifolds,"In this paper, we investigate the problem of blow up and sharp upper bound
+estimates of the lifespan for the solutions to the semilinear wave equations,
+posed on asymptotically Euclidean manifolds. Here the metric is assumed to be
+exponential perturbation of the spherical symmetric, long range asymptotically
+Euclidean metric. One of the main ingredients in our proof is the construction
+of (unbounded) positive entire solutions for
+$\Delta_{g}\phi_\lambda=\lambda^{2}\phi_\lambda$, with certain estimates which
+are uniform for small parameter $\lambda\in (0,\lambda_0)$. In addition, our
+argument works equally well for semilinear damped wave equations, when the
+coefficient of the dissipation term is integrable (without sign condition) and
+space-independent.",1912.02540v1
+2019-12-08,Dynamical Primal-Dual Accelerated Method with Applications to Network Optimization,"This paper develops a continuous-time primal-dual accelerated method with an
+increasing damping coefficient for a class of convex optimization problems with
+affine equality constraints. This paper analyzes critical values for parameters
+in the proposed method and prove that the rate of convergence in terms of the
+duality gap function is $O(\tfrac{1}{t^2})$ by choosing suitable parameters. As
+far as we know, this is the first continuous-time primal-dual accelerated
+method that can obtain the optimal rate. Then this work applies the proposed
+method to two network optimization problems, a distributed optimization problem
+with consensus constraints and a distributed extended monotropic optimization
+problem, and obtains two variant distributed algorithms. Finally, numerical
+simulations are given to demonstrate the efficacy of the proposed method.",1912.03690v2
+2020-01-08,Assessing different approaches to ab initio calculations of spin wave stiffness,"Ab initio calculations of the spin wave stiffness constant $D$ for elemental
+Fe and Ni performed by different groups in the past have led to values with a
+considerable spread of 50-100 %. We present results for the stiffness constant
+$D$ of Fe, Ni, and permalloy Fe$_{0.19}$Ni$_{0.81}$ obtained by three different
+approaches: (i) by finding the quadratic term coefficient of the power
+expansion of the spin wave energy dispersion, (ii) by a damped real-space
+summation of weighted exchange coupling constants, and (iii) by integrating the
+appropriate expression in reciprocal space. All approaches are implemented by
+means of the same Korringa-Kohn-Rostoker (KKR) Green function formalism. We
+demonstrate that if properly converged, all procedures yield comparable values,
+with uncertainties of 5-10 % remaining. By a careful analysis of the influence
+of various technical parameters we estimate the margin of errors for the
+stiffness constants evaluated by different approaches and suggest procedures to
+minimize the risk of getting incorrect results.",2001.02558v2
+2020-02-12,Exact Solution for the Heat Conductance in Harmonic Chains,"We present an exact solution for the heat conductance along a harmonic chain
+connecting two reservoirs at different temperatures. In this model, the end
+points correspond to Brownian particles with different damping coefficients.
+Such analytical expression for the heat conductance covers its behavior from
+mesoscopic to very long one-dimensional quantum chains, and validates the
+ballistic nature of the heat transport in the latter example. This implies the
+absence of the Fourier law for classical and quantum harmonic chains. We also
+provide a thorough analysis of the normal modes of system which helps us to
+satisfactorily interpret these results.",2002.05195v2
+2020-04-17,On Enhanced Dissipation for the Boussinesq Equations,"In this article we consider the stability and damping problem for the 2D
+Boussinesq equations with partial dissipation near a two parameter family of
+stationary solutions which includes Couette flow and hydrostatic balance.
+  In the first part we show that for the linearized problem in an infinite
+periodic channel the evolution is asymptotically stable if any diffusion
+coefficient is non-zero. In particular, this imposes weaker conditions than for
+example vertical diffusion. Furthermore, we study the interaction of shear
+flow, hydrostatic balance and partial dissipation.
+  In a second part we adapt the methods used by Bedrossian, Vicol and Wang in
+the Navier-Stokes problem and combine them with cancellation properties of the
+Boussinesq equations to establish small data stability and enhanced dissipation
+results for the nonlinear Boussinesq problem with full dissipation.",2004.08125v1
+2020-05-05,Heavy quark diffusion in an overoccupied gluon plasma,"We extract the heavy-quark diffusion coefficient \kappa and the resulting
+momentum broadening <p^2> in a far-from-equilibrium non-Abelian plasma. We find
+several features in the time dependence of the momentum broadening: a short
+initial rapid growth of <p^2>, followed by linear growth with time due to
+Langevin-type dynamics and damped oscillations around this growth at the
+plasmon frequency. We show that these novel oscillations are not easily
+explained using perturbative techniques but result from an excess of gluons at
+low momenta. These oscillation are therefore a gauge invariant confirmation of
+the infrared enhancement we had previously observed in gauge-fixed correlation
+functions. We argue that the kinetic theory description of such systems becomes
+less reliable in the presence of this IR enhancement.",2005.02418v2
+2020-09-02,Frustrated bearings,"In a bearing state, touching spheres (disks in two dimensions) roll on each
+other without slip. Here we frustrate a system of touching spheres by imposing
+two different bearing states on opposite sides and search for the
+configurations of lowest energy dissipation. If the dissipation between
+contacts of spheres is viscous (with random damping constants), the angular
+momentum continuously changes from one bearing state to the other. For Coulomb
+friction (with random friction coefficients) in two dimensions, a sharp line
+separates the two bearing states and we show that this line corresponds to the
+minimum cut. Astonishingly however, in three dimensions, intermediate bearing
+domains, that are not synchronized with either side, are energetically more
+favorable than the minimum-cut surface. Instead of a sharp cut, the steady
+state displays a fragmented structure. This novel type of state of minimum
+dissipation is characterized by a spanning network of slipless contacts that
+reaches every sphere. Such a situation becomes possible because in three
+dimensions bearing states have four degrees of freedom.",2009.01295v1
+2020-11-02,On the stability of Bresse and Timoshenko systems with hyperbolic heat conduction,"We investigate the stability of three thermoelastic beam systems with
+hyperbolic heat conduction. First, we study the Bresse-Gurtin-Pipkin system,
+providing a necessary and sufficient condition for the exponential stability
+and the optimal polynomial decay rate when the condition is violated. Second,
+we obtain analogous results for the Bresse-Maxwell-Cattaneo system, completing
+an analysis recently initiated in the literature. Finally, we consider the
+Timoshenko-Gurtin-Pipkin system and we find the optimal polynomial decay rate
+when the known exponential stability condition does not hold. As a byproduct,
+we fully recover the stability characterization of the
+Timoshenko-Maxwell-Cattaneo system. The classical ""equal wave speeds""
+conditions are also recovered through singular limit procedures. Our conditions
+are compatible with some physical constraints on the coefficients as the
+positivity of the Poisson's ratio of the material. The analysis faces several
+challenges connected with the thermal damping, whose resolution rests on
+recently developed mathematical tools such as quantitative Riemann-Lebesgue
+lemmas.",2011.00994v2
+2020-11-21,A Trace-restricted Kronecker-Factored Approximation to Natural Gradient,"Second-order optimization methods have the ability to accelerate convergence
+by modifying the gradient through the curvature matrix. There have been many
+attempts to use second-order optimization methods for training deep neural
+networks. Inspired by diagonal approximations and factored approximations such
+as Kronecker-Factored Approximate Curvature (KFAC), we propose a new
+approximation to the Fisher information matrix (FIM) called Trace-restricted
+Kronecker-factored Approximate Curvature (TKFAC) in this work, which can hold
+the certain trace relationship between the exact and the approximate FIM. In
+TKFAC, we decompose each block of the approximate FIM as a Kronecker product of
+two smaller matrices and scaled by a coefficient related to trace. We
+theoretically analyze TKFAC's approximation error and give an upper bound of
+it. We also propose a new damping technique for TKFAC on convolutional neural
+networks to maintain the superiority of second-order optimization methods
+during training. Experiments show that our method has better performance
+compared with several state-of-the-art algorithms on some deep network
+architectures.",2011.10741v1
+2020-12-12,Stabilized explicit Adams-type methods,"In this work we present explicit Adams-type multistep methods with extended
+stability interval, which are analogous to the stabilized Chebyshev
+Runge--Kutta methods. It is proved that for any $k\geq 1$ there exists an
+explicit $k$-step Adams-type method of order one with stability interval of
+length $2k$. The first order methods have remarkably simple expressions for
+their coefficients and error constant. A damped modification of these methods
+is derived. In general case to construct a $k$-step method of order $p$ it is
+necessary to solve a constrained optimization problem in which the objective
+function and $p$ constraints are second degree polynomials in $k$ variables. We
+calculate higher-order methods up to order six numerically and perform some
+numerical experiments to confirm the accuracy and stability of the methods.",2012.06767v1
+2020-12-18,Intermodal Brillouin scattering in solid-core photonic crystal fibers,"We investigate intermodal forward Brillouin scattering in a solid-core PCF,
+demonstrating efficient power conversion between the HE11 and HE21 modes, with
+a maximum gain coefficient of 21.4/W/km. By exploring mechanical modes of
+different symmetries, we observe both polarization-dependent and
+polarization-independent intermodal Brillouin interaction. Finally, we discuss
+the role of squeeze film air damping and leakage mechanisms, ultimately
+critical to the engineering of PCF structures with enhanced interaction between
+high order optical modes through flexural mechanical modes.",2012.10007v1
+2021-04-25,Multiphoton resonance in a driven Kerr oscillator in presence of high-order nonlinearities,"We considered the multiphoton resonance in the periodically driven quantum
+oscillator with Kerr nonlinearity in the presence of weak high-order
+nonlinearities. Multiphoton resonance leads to the emergence of peaks and dips
+in the dependence of the stationary occupations of the stable states on
+detuning. We demonstrated that due to high-order nonlinearities, these peaks
+and dips acquire additional fine structure and split into several closely
+spaced ones. Quasiclassically, multiphoton resonance is treated as tunneling
+between the regions of the oscillator phase portrait, and the fine structure of
+the multiphoton resonance is a consequence of a special quasienergy dependence
+of the tunneling rate between different regions of the classical phase
+portrait. For different values of damping and high-order nonlinearity
+coefficients, we identified the domain of quasienergies where tunneling
+strongly influences the system kinetics. The corresponding tunneling term in
+the Fokker-Planck equation in quasienergy space was derived directly from the
+quantum master equation.",2104.12140v2
+2021-04-27,Green's functions and the Cauchy problem of the Burgers hierarchy and forced Burgers equation,"We consider the Cauchy problem for the Burgers hierarchy with general time
+dependent coefficients. The closed form for the Green's function of the
+corresponding linear equation of arbitrary order $N$ is shown to be a sum of
+generalised hypergeometric functions. For suitably damped initial conditions we
+plot the time dependence of the Cauchy problem over a range of $N$ values. For
+$N=1$, we introduce a spatial forcing term. Using connections between the
+associated second order linear Schr\""{o}dinger and Fokker-Planck equations, we
+give closed form expressions for the corresponding Green's functions of the
+sinked Bessel process with constant drift. We then apply the Green's function
+to give time dependent profiles for the corresponding forced Burgers Cauchy
+problem.",2104.12976v1
+2021-05-27,Polarization-dependent excitons and plasmon activity in nodal-line semimetal ZrSiS,"The optical properties of bulk ZrSiS nodal-line semimetal are theoretically
+studied within a many-body formalism. The G0W0 bands are similar to those
+calculated within the density functional theory, except near the {\Gamma}
+point; in particular, no significant differences are found around the Fermi
+energy. On the other hand, the solution of the Bethe-Salpeter equation reveals
+a significant excitonic activity, mostly as dark excitons which appear in a
+wide energy range. Bright excitons, on the contrary, are less numerous, but
+their location and intensity depend greatly on the polarization of the incident
+electric field, as the absorption coefficient itself does. The binding energy
+of these excitons correlate well with their spatial distribution functions. In
+any case, a good agreement with available experimental data for
+absorption-reflection is achieved. Finally, the possible activation of plasma
+oscillations at low energies is discarded, because these are damped by
+producing electron-hole pairs, more importantly for q along the {\Gamma}-M
+path.",2105.13285v1
+2021-07-07,Growth of Aggregates with Liquid-Like Ice-Shells in Protoplanetary Discs,"During the first stages of planet formation, the collision growth of dust
+aggregates in protoplanetary discs (PPDs) is interrupted at the bouncing
+barrier. Dust aggregates coated by different species of ice turn out to be
+helpful to shift the bouncing barrier towards larger sizes due to their
+enhanced sticking properties in some cases. A rarely noticed fact is that
+H$_2$O- and H$_2$O-CH$_3$OH-NH$_3$-ice behave liquid-like when UV-irradiated
+within a PPD-similar environment. Dust aggregates coated by these ice species
+might be damped in collisions due to the liquid-like ice-shell which would
+effectively results in an increase of the sticking velocity. In this work,
+collisions of dust aggregates covered by the liquid-like
+H$_2$O-CH$_3$OH-NH$_3$-ice-shell are considered numerically. The coefficient of
+restitution and the sticking velocity are calculated for different thicknesses
+of the ice-shell. The simulation predicts that an ice-shell-thickness of few
+microns would be sufficient to allow the growth of cm-sized clusters in the
+PPD.",2107.03188v1
+2021-07-08,A Comparison of Data-Driven Techniques for Power Grid Parameter Estimation,"Power grid parameter estimation involves the estimation of unknown
+parameters, such as inertia and damping coefficients, using observed dynamics.
+In this work, we present a comparison of data-driven algorithms for the power
+grid parameter estimation problem. First, we propose a new algorithm to solve
+the parameter estimation problem based on the Sparse Identification of
+Nonlinear Dynamics (SINDy) approach, which uses linear regression to infer the
+parameters that best describe the observed data. We then compare its
+performance against two benchmark algorithms, namely, the unscented Kalman
+filter (UKF) approach and the physics-informed neural networks (PINN) approach.
+We perform extensive simulations on IEEE bus systems to examine the performance
+of the aforementioned algorithms. Our results show that the SINDy algorithm
+outperforms the PINN and UKF algorithms in being able to accurately estimate
+the power grid parameters over a wide range of system parameters (including
+high and low inertia systems). Moreover, it is extremely efficient
+computationally and so takes significantly less time than the PINN algorithm,
+thus making it suitable for real-time parameter estimation.",2107.03762v1
+2021-08-09,Learning Langevin dynamics with QCD phase transition,"In this proceeding, the deep Convolutional Neural Networks (CNNs) are
+deployed to recognize the order of QCD phase transition and predict the
+dynamical parameters in Langevin processes. To overcome the intrinsic
+randomness existed in a stochastic process, we treat the final spectra as
+image-type inputs which preserve sufficient spatiotemporal correlations. As a
+practical example, we demonstrate this paradigm for the scalar condensation in
+QCD matter near the critical point, in which the order parameter of chiral
+phase transition can be characterized in a $1+1$-dimensional Langevin equation
+for $\sigma$ field. The well-trained CNNs accurately classify the first-order
+phase transition and crossover from $\sigma$ field configurations with
+fluctuations, in which the noise does not impair the performance of the
+recognition. In reconstructing the dynamics, we demonstrate it is robust to
+extract the damping coefficients $\eta$ from the intricate field
+configurations.",2108.03987v1
+2021-08-21,Consistent SPH simulations of the anisotropic dispersion of a contaminant plume,"Solute transport through heterogeneous porous media is governed by fuid
+advection, molecular diffusion and anisotropic dispersion. The dispersion is
+assumed to obey Fick's law and the dispersion coefficient is defined as a
+second rank tensor. However, this problem has revealed to be a very difficult
+one because independently of the numerical methods employed, the solutions are
+seen to exhibit artificial oscillations and negative concentrations when the
+dispersivity becomes anisotropic. Here we report consistent SPH simulations of
+the anisotropic dispersion of a Gaussian contaminant plume in porous media
+using the open source code DualSPHysics. Consistency of the SPH method is
+restored by increasing the spatial resolution along with the number of
+neighbours within the compact support of the interpolating kernel. The solution
+shows that as the number of neighbours is increased with resolution, full
+convergence of the numerical solutions is guaranteed regardless of the
+dispersivity. However, despite the restored consistency, negative
+concentrations, albeit at a lower level, are still present. This suggests that
+a compromise between the number of neighbours and the size of the smoothing
+length must be guaranteed such that sufficient implicit numerical diffusion
+remains to damp out unphysical oscillations.",2108.09488v1
+2021-11-01,Retesting the no-hair theorem with GW150914,"For a distorted black hole (BH), its ringdown waveform is a superposition of
+quasi-normal modes (QNMs). In general relativity (GR), the lower order QNM
+frequencies and damping rates can be well approximated by a polynomial of BH's
+dimensionless spin and overall scaled by BH's mass. That is to say, we can test
+the no-hair theorem of BH in GR model-independently by allowing not only an
+overall fractional deviation (as M. Isi {\it et al.} did) but also a set of
+fractional deviation for every coefficient. In the paper, we will apply the
+latter method to retest the no-hair theorem with GW150914 and probe hairs'
+behaviors if hairs exist. Eventually, we find the data favors GR.",2111.00953v2
+2021-11-17,Global stability dynamics of the timelike extremal hypersurfaces in Minkowski space,"This paper aims to study the relationship between the timelike extremal
+hypersurfaces and the classical minimal surfaces. This target also gives the
+long time dynamics of timelike extremal hypersurfaces in Minkowski spacetime
+$\mathbb{R}^{1+M}$ with the dimension $2\leq M\leq7$. In this dimension, the
+stationary solution of timelike extremal hypersurface equation is the solution
+of classical minimal surface equation, which only admits the hyperplane
+solution by Bernstein theorem. We prove that this hyperplane solution as the
+stationary solution of timelike extremal hypersurface equation is asymptotic
+stablely by finding the hidden dissipative structure of linearized equation.
+Here we overcome that the vector field method (based on the energy estimate and
+bootstrap argument) is lose effectiveness due to the lack of time-decay of
+solution for the linear perturbation equation. Meanwhile, a global well-posed
+result of linear damped wave with variable time-space coefficients is
+established. Hence, our result construct a unique global timelike non-small
+solution near the hyperplane.",2111.08877v3
+2021-11-17,A Generalized Proportionate-Type Normalized Subband Adaptive Filter,"We show that a new design criterion, i.e., the least squares on subband
+errors regularized by a weighted norm, can be used to generalize the
+proportionate-type normalized subband adaptive filtering (PtNSAF) framework.
+The new criterion directly penalizes subband errors and includes a sparsity
+penalty term which is minimized using the damped regularized Newton's method.
+The impact of the proposed generalized PtNSAF (GPtNSAF) is studied for the
+system identification problem via computer simulations. Specifically, we study
+the effects of using different numbers of subbands and various sparsity penalty
+terms for quasi-sparse, sparse, and dispersive systems. The results show that
+the benefit of increasing the number of subbands is larger than promoting
+sparsity of the estimated filter coefficients when the target system is
+quasi-sparse or dispersive. On the other hand, for sparse target systems,
+promoting sparsity becomes more important. More importantly, the two aspects
+provide complementary and additive benefits to the GPtNSAF for speeding up
+convergence.",2111.08952v1
+2021-12-07,Complexity for Open Quantum System,"We study the complexity for an open quantum system. Our system is a harmonic
+oscillator coupled to a one-dimensional massless scalar field, which acts as
+the bath. Specifically, we consider the reduced density matrix by tracing out
+the bath degrees of freedom for both regular and inverted oscillator and
+computed the complexity of purification (COP) and complexity by using the
+operator-state mapping. We found that when the oscillator is regular the COP
+saturates quickly for both underdamped and overdamped oscillators.
+Interestingly, when the oscillator is underdamped, we discover a kink like
+behaviour for the saturation value of COP with varying damping coefficient. For
+the inverted oscillator, we found a linear growth of COP with time for all
+values of bath-system interaction. However, when the interaction is increased
+the slope of the linear growth decreases, implying that the unstable nature of
+the system can be regulated by the bath.",2112.03955v1
+2021-12-14,Strong coupling in a Au plasmonic antenna-SiO$_{2}$ layer system: a hybrid mode analysis,"A detailed analysis of the optical response of a system accommodating several
+coupled modes is needed for the complete understanding of the strong coupling
+effect. In this paper, we report on the analysis of scattering cross section
+spectra of Au antennas on a SiO$_{2}$ layer on a Si substrate in the IR region.
+A classical model of coupled oscillators is used for determining the resonant
+energies, damping rates and coupling strengths of four phonon polariton modes
+in the SiO$_{2}$ layer coupled to a localized surface plasmon mode in a Au
+antenna. The calculated Hopfield mixing coefficients then show the contribution
+of the individual uncoupled modes to the hybrid modes of the coupled system.",2112.07767v1
+2021-12-22,Dynamic structure factor of the magnetized one-component plasma: crossover from weak to strong coupling,"Plasmas in strong magnetic fields have been mainly studied in two distinct
+limiting cases--that of weak and strong nonideality with very different
+physical properties. While the former is well described by the familiar theory
+of Braginskii, the latter regime is closer to the behavior of a Coulomb liquid.
+Here we study in detail the transition between both regimes. We focus on the
+evolution of the dynamic structure factor of the magnetized one-component
+plasma from weak to strong coupling, which is studied with first-principle
+molecular dynamics simulations. The simulations show the vanishing of Bernstein
+modes and the emergence of higher harmonics of the upper hybrid mode across the
+magnetic field, a redistribution of spectral power between the two main
+collective modes under oblique angles, and a suppression of plasmon damping
+along the magnetic field. Comparison with results from various models,
+including the random phase approximation, a Mermin-type dielectric function,
+and the Quasi-Localized Charge Approximation show that none of the theories is
+capable of reproducing the crossover that occurs when the coupling parameter is
+on the order of unity. The findings are relevant to the scattering spectra,
+stopping power, and transport coefficients of correlated magnetized plasmas.",2112.11981v1
+2021-12-29,Stabilization results for delayed fifth order KdV-type equation in a bounded domain,"Studied here is the Kawahara equation, a fifth order Korteweg-de Vries type
+equation, with time-delayed internal feedback. Under suitable assumptions on
+the time delay coefficients we prove that solutions of this system are
+exponentially stable. First, considering a damping and delayed system, with
+some restriction of the spatial length of the domain, we prove that the
+Kawahara system is exponentially stable for $T> T_{\min}$. After that,
+introducing a more general delayed system, and by introducing suitable
+energies, we show using Lyapunov approach, that the energy of the Kawahara
+equation goes to zero exponentially, considering the initial data small and a
+restriction in the spatial length of the domain. To remove these hypotheses, we
+use the compactness-uniqueness argument which reduces our problem to prove an
+observability inequality, showing a semi-global stabilization result.",2112.14854v1
+2022-01-25,Dissipative Hamiltonian Neural Networks: Learning Dissipative and Conservative Dynamics Separately,"Understanding natural symmetries is key to making sense of our complex and
+ever-changing world. Recent work has shown that neural networks can learn such
+symmetries directly from data using Hamiltonian Neural Networks (HNNs). But
+HNNs struggle when trained on datasets where energy is not conserved. In this
+paper, we ask whether it is possible to identify and decompose conservative and
+dissipative dynamics simultaneously. We propose Dissipative Hamiltonian Neural
+Networks (D-HNNs), which parameterize both a Hamiltonian and a Rayleigh
+dissipation function. Taken together, they represent an implicit Helmholtz
+decomposition which can separate dissipative effects such as friction from
+symmetries such as conservation of energy. We train our model to decompose a
+damped mass-spring system into its friction and inertial terms and then show
+that this decomposition can be used to predict dynamics for unseen friction
+coefficients. Then we apply our model to real world data including a large,
+noisy ocean current dataset where decomposing the velocity field yields useful
+scientific insights.",2201.10085v2
+2022-02-08,Spin waves in spin hydrodynamics,"The propagation properties of spin degrees of freedom are analyzed in the
+framework of relativistic hydrodynamics with spin based on the de Groot--van
+Leeuwen--van Weert definitions of the energy-momentum and spin tensors. We
+derive the analytical expression for the spin wave velocity for arbitrary
+statistics and show that it goes to half the speed of light in the
+ultra-relativistic limit. We find that only the transverse degrees of freedom
+propagate, analogously to electromagnetic waves. Finally, we consider the
+effect of dissipative corrections and calculate the damping coefficients for
+the case of Maxwell-J\""uttner statistics.",2202.03952v2
+2022-03-14,Eliashberg theory of the Jahn-Teller-Hubbard model,"We study a multiorbital Hubbard model coupled to local Jahn-Teller phonons to
+investigate the superconducting state realized in fullerides. A weak-coupling
+approach is employed in combination with a local self-energy approximation. In
+addition to the normal and anomalous self-energies of the electrons, we
+consider the phonon self-energy, which allows a self-consistent treatment of
+the energetics. The frequency dependence of the self-energies and their
+characteristic coefficients, such as renormalization factors and dampings, are
+investigated in detail using numerical calculations. It is clarified that the
+anisotropic phonons play an important role in the stabilization of the
+superconducting state. By comparing the full results to those without phonon
+self-energies, we show that the superconductivity is stabilized by the
+softening of the phonon frequency. The effects of electronic fluctuations are
+also considered, which leads to the coupling to orbitons, an analog of plasmons
+in the electron gas. This additional contribution further stabilizes the
+superconducting state.",2203.06946v1
+2022-04-20,A theoretical framework for the Hamiltonian of angular momentum optomechanical system,"Photon carries linear momentum and angular momentum simultaneously. Within
+the light-matter interaction process, exchange of linear momentum results in
+optical forces, whereas exchange of angular momentum leads to optical torques.
+Use of optical forces (light pressure or damping) have been long and wide in
+quantum optomechanics, however, those of optical torque and optical angular
+momentum are not. Here we propose a theoretical framework based on optical
+angular momentum and optical torques to derive the Hamiltonians of cavity
+orbital and spin angular momentum optomechanical systems, respectively.
+Moreover, based on the method, we successfully obtain the Hamiltonian of the
+complex angular momentum optomechanical systems consisting of micro-cavity and
+several torsional oscillators, whose reflection coefficients are non-unit. Our
+results indicate the general applicability of our theoretical framework for the
+Hamiltonian of angular momentum optomechanical systems and extend the research
+scope of quantum optomechanics.",2204.09446v2
+2022-05-17,Acoustic gravitational interaction revised,"In this paper, we deduce the expression of the gravito-acoustic force between
+two oscillating bubbles using the hypothesis that this type of force is a force
+of scattering-absorption of the energy of excitatory waves. The expression of
+the gravito-acoustic force at resonance highlights the dependence of this force
+on the product of the virtual masses of the two bubbles and on an acoustic
+gravitational constant. The acoustic gravitational constant depends on the
+absorption damping coefficient. We may say also that the expression of the
+acoustic gravitational constant is analogous to the expression of the
+gravitational constant in the electromagnetic world, that one obtained in the
+Einstein-Sciama model and the Dirac-Eddington large numbers hypothesis. The
+results obtained for this type of phenomenon in the acoustic world support the
+similarity between the acoustic world and the electromagnetic world.",2206.00435v1
+2022-06-03,Kinetic chemotaxis tumbling kernel determined from macroscopic quantities,"Chemotaxis is the physical phenomenon that bacteria adjust their motions
+according to chemical stimulus. A classical model for this phenomenon is a
+kinetic equation that describes the velocity jump process whose
+tumbling/transition kernel uniquely determines the effect of chemical stimulus
+on bacteria. The model has been shown to be an accurate model that matches with
+bacteria motion qualitatively. For a quantitative modeling, biophysicists and
+practitioners are also highly interested in determining the explicit value of
+the tumbling kernel. Due to the experimental limitations, measurements are
+typically macroscopic in nature. Do macroscopic quantities contain enough
+information to recover microscopic behavior? In this paper, we give a positive
+answer. We show that when given a special design of initial data, the
+population density, one specific macroscopic quantity as a function of time,
+contains sufficient information to recover the tumbling kernel and its
+associated damping coefficient. Moreover, we can read off the chemotaxis
+tumbling kernel using the values of population density directly from this
+specific experimental design. This theoretical result using kinetic theory
+sheds light on how practitioners may conduct experiments in laboratories.",2206.01629v2
+2022-06-28,Origin of the spontaneous oscillations in a simplified coagulation-fragmentation system driven by a source,"We consider a system of aggregated clusters of particles, subjected to
+coagulation and fragmentation processes with mass dependent rates. Each monomer
+particle can aggregate with larger clusters, and each cluster can fragment into
+individual monomers with a rate directly proportional to the aggregation rate.
+The dynamics of the cluster densities is governed by a set of Smoluchowski
+equations, and we consider the addition of a source of monomers at constant
+rate. The whole dynamics can be reduced to solving a unique non-linear
+differential equation which displays self-oscillations in a specific range of
+parameters, and for a number of distinct clusters in the system large enough.
+This collective phenomenon is due to the presence of a fluctuating damping
+coefficient and is closely related to the Li\'enard self-oscillation mechanism
+observed in a more general class of physical systems such as the van der Pol
+oscillator.",2206.13884v1
+2022-07-25,Modelling and well-posedness of evolutionary differential variational-hemivariational inequalities,"In this paper, we study the well-posedness of a class of evolutionary
+variational-hemivariational inequalities coupled with a nonlinear ordinary
+differential equation in Banach spaces. The proof is based on an iterative
+approximation scheme showing that the problem has a unique mild solution. In
+addition, we established continuity of the flow map with respect to the initial
+data. Under the general framework, we consider two new applications for
+modelling of frictional contact with viscoelastic materials, where the friction
+coefficient $\mu$ depends on an external state variable $\alpha$ and the slip
+rate $|\dot{u}_\tau|$. In the first application, we consider Coulomb friction
+with normal compliance, and in the second, normal damped response. In both
+cases, we present a new first-order approximation of the Dieterich
+rate-and-state friction law.",2207.12284v2
+2022-08-05,Giant oscillations of diffusion in ac-driven periodic systems,"We revisit the problem of diffusion in a driven system consisting of an
+inertial Brownian particle moving in a symmetric periodic potential and
+subjected to a symmetric time-periodic force. We reveal parameter domains in
+which diffusion is normal in the long time limit and exhibits intriguing giant
+damped quasiperiodic oscillations as a function of the external driving
+amplitude. As the mechanism behind this effect we identify the corresponding
+oscillations of difference in the number of locked and running trajectories
+which carries the leading contribution to the diffusion coefficient. Our
+findings can be verified experimentally in a multitude of physical systems
+including colloidal particles, Josephson junction or cold atoms dwelling in
+optical lattices, to name only a few.",2208.03223v2
+2022-08-24,Out-of-equilibrium optomechanical resonance self-excitation,"The fundamental sensitivity limit of atomic force microscopy is strongly
+correlated to the thermal noise of the cantilever oscillation. A method to
+suppress this unwanted noise is to reduce the bandwidth of the measurement, but
+this approach is limited by the speed of the measurement and the width of the
+cantilever resonance, commonly defined through the quality factor Q. However,
+it has been shown that optomechanical resonances in interferometers might
+affect the cantilever oscillations resulting in an effective quality factor
+Q$_{eff}$ . When the laser power is sufficiently increased the cantilever
+oscillations might even reach the regime of self-oscillation. In this
+self-oscillation state, the noise of the system is partially determined by the
+interaction with the laser light far from equilibrium. Here, we show and
+discuss how tuning of the laser power leads to nonlinear optomechanical effects
+that can dramatically increase the effective quality factor of the cantilever
+leading to out-of-equilibrium noise. We model the effects using a fourth order
+nonlinearity of the damping coefficient.",2208.11390v1
+2022-09-19,Stationary states of an active Brownian particle in a harmonic trap,"We study the stationary states of an over-damped active Brownian particle
+(ABP) in a harmonic trap in two dimensions, via mathematical calculations and
+numerical simulations. In addition to translational diffusion, the ABP
+self-propels with a certain velocity, whose magnitude is constant, but its
+direction is subject to Brownian rotation. In the limit where translational
+diffusion is negligible, the stationary distribution of the particle's position
+shows a transition between two different shapes, one with maximum and the other
+with minimum density at the centre, as the trap stiffness is increased. We show
+that this non-intuitive behaviour is captured by the relevant Fokker-Planck
+equation, which, under minimal assumptions, predicts a continuous ``phase
+transition"" between the two different shapes. As the translational diffusion
+coefficient is increased, both these distributions converge into the
+equilibrium, Boltzmann form. Our simulations support the analytical
+predictions, and also show that the probability distribution of the orientation
+angle of the self-propulsion velocity undergoes a transition from unimodal to
+bimodal forms in this limit. We also extend our simulations to a three
+dimensional trap, and find similar behaviour.",2209.09184v2
+2022-10-07,Optimal Energy Shaping Control for a Backdrivable Hip Exoskeleton,"Task-dependent controllers widely used in exoskeletons track predefined
+trajectories, which overly constrain the volitional motion of individuals with
+remnant voluntary mobility. Energy shaping, on the other hand, provides
+task-invariant assistance by altering the human body's dynamic characteristics
+in the closed loop. While human-exoskeleton systems are often modeled using
+Euler-Lagrange equations, in our previous work we modeled the system as a
+port-controlled-Hamiltonian system, and a task-invariant controller was
+designed for a knee-ankle exoskeleton using interconnection-damping assignment
+passivity-based control. In this paper, we extend this framework to design a
+controller for a backdrivable hip exoskeleton to assist multiple tasks. A set
+of basis functions that contains information of kinematics is selected and
+corresponding coefficients are optimized, which allows the controller to
+provide torque that fits normative human torque for different activities of
+daily life. Human-subject experiments with two able-bodied subjects
+demonstrated the controller's capability to reduce muscle effort across
+different tasks.",2210.03777v2
+2022-10-18,Nanoscale friction controlled by top layer thickness in [LaMnO$_{3}$]$_{m}$/[SrMnO$_{3}$]$_{n}$ superlattices,"We conducted lateral force microscopy measurements on seven
+[LaMnO$_{3}$]$_{m}$/[SrMnO$_{3}$]$_{n}$ superlattices with varied layer
+thicknesses. We observe that the friction forces and the friction coefficients
+initially increase with increasing LaMnO3 top layer thickness, followed by
+saturation when the top layer thickness exceeds a few nanometers. These
+observations clearly demonstrate that sliding friction is affected by
+sub-surface material properties to a depth of several nanometers and is not
+just determined by dynamics in the contact interface. We argue that the
+sub-surface dissipated energy is governed by damping in the elastically
+strained volume below the AFM tip, an effect which we estimate via
+thermoelasticity. The absence of a correlation between friction and the thermal
+resistivity of our superlattices shows furthermore that high-frequency phonons
+and heat conduction do not play a role in determining friction. Our
+observations thus demonstrate that friction can be tailored by sub-surface
+material properties.",2210.09677v1
+2022-12-15,Resonant and off-resonant magnetoacoustic waves in epitaxial Fe$_3$Si/GaAs hybrid structures,"Surface acoustic waves (SAWs) provide an efficient dynamical coupling between
+strain and magnetization in micro/nano-metric devices. Using a hybrid device
+composed of a piezoelectric, GaAs, and a ferromagnetic Heusler alloy thin film,
+Fe$_3$Si, we are able to quantify the amplitude of magnetoacoustic waves
+generated with SAWs via magnetic imaging in an X-ray photoelectron microscope.
+The cubic anisotropy of the sample together with a low damping coefficient
+allows for the observation of resonant and non-resonant magnetoelastic
+coupling. Additionally, via micromagnetic simulation, we verify the
+experimental behavior and quantify the magnetoelastic shear strain component in
+Fe$_3$Si that appears to be very large ($b_2=14\times 10^6$ J/m$^3$), much
+larger than the one found in Nickel.",2212.07994v1
+2022-12-22,State-and-rate friction in contact-line dynamics,"In order to probe the dynamics of contact-line motion, we study the
+macroscopic properties of sessile drops deposited on and then aspirated from
+carefully prepared horizontal surfaces. By measuring the contact angle and drop
+width simultaneously during droplet removal, we determine the changes in the
+shape of the drop as it depins and recedes. Our data indicate that there is a
+force which opposes the motion of the contact line that depends both on the
+amount of time that the drop has been in contact with the surface and on the
+withdrawal rate. For water on silanized glass, we capture the experimentally
+observed behavior with an overdamped dynamical model of contact-line motion in
+which the phenomenological drag coefficient and the assumed equilibrium contact
+angle are the only inputs. For other liquid/substrate pairs, the observed
+contact-line motion suggests that a maximum static friction force is important
+in addition to damping. The dependence on time of contact and withdrawal rate,
+reminiscent of rate-and-state friction between solid surfaces, is qualitatively
+consistent across three substrate-liquid pairs.",2212.11759v1
+2023-02-07,SDYN-GANs: Adversarial Learning Methods for Multistep Generative Models for General Order Stochastic Dynamics,"We introduce adversarial learning methods for data-driven generative modeling
+of the dynamics of $n^{th}$-order stochastic systems. Our approach builds on
+Generative Adversarial Networks (GANs) with generative model classes based on
+stable $m$-step stochastic numerical integrators. We introduce different
+formulations and training methods for learning models of stochastic dynamics
+based on observation of trajectory samples. We develop approaches using
+discriminators based on Maximum Mean Discrepancy (MMD), training protocols
+using conditional and marginal distributions, and methods for learning dynamic
+responses over different time-scales. We show how our approaches can be used
+for modeling physical systems to learn force-laws, damping coefficients, and
+noise-related parameters. The adversarial learning approaches provide methods
+for obtaining stable generative models for dynamic tasks including long-time
+prediction and developing simulations for stochastic systems.",2302.03663v1
+2023-02-26,Topology optimization method with nonlinear diffusion,"This paper is concerned with topology optimization based on a level set
+method using (doubly) nonlinear diffusion equations. Topology optimization
+using the level set method is called level set-based topology optimization,
+which is possible to determine optimal configurations that minimize objective
+functionals by updating level set functions. In this paper, as an update
+equation for level set functions, (doubly) nonlinear diffusion equations with
+reaction terms are derived, and then the singularity and degeneracy of the
+diffusion coefficient are applied to obtain fast convergence of configurations
+and damping oscillation on boundary structures. In particular, the reaction
+terms in the proposed method do not depend on the topological derivatives, and
+therefore, sensitivity analysis to determine a descent direction for objective
+functionals is relaxed. Furthermore, a numerical algorithm for the proposed
+method is constructed and applied to typical minimization problems to show
+numerical validity. This paper is a justification and generalization of the
+method using reaction-diffusion equations developed by one of the authors in
+Yamada et al. (2010).",2302.13310v1
+2023-02-27,Natural Gradient Hybrid Variational Inference with Application to Deep Mixed Models,"Stochastic models with global parameters $\bm{\theta}$ and latent variables
+$\bm{z}$ are common, and variational inference (VI) is popular for their
+estimation. This paper uses a variational approximation (VA) that comprises a
+Gaussian with factor covariance matrix for the marginal of $\bm{\theta}$, and
+the exact conditional posterior of $\bm{z}|\bm{\theta}$. Stochastic
+optimization for learning the VA only requires generation of $\bm{z}$ from its
+conditional posterior, while $\bm{\theta}$ is updated using the natural
+gradient, producing a hybrid VI method. We show that this is a well-defined
+natural gradient optimization algorithm for the joint posterior of
+$(\bm{z},\bm{\theta})$. Fast to compute expressions for the Tikhonov damped
+Fisher information matrix required to compute a stable natural gradient update
+are derived. We use the approach to estimate probabilistic Bayesian neural
+networks with random output layer coefficients to allow for heterogeneity.
+Simulations show that using the natural gradient is more efficient than using
+the ordinary gradient, and that the approach is faster and more accurate than
+two leading benchmark natural gradient VI methods. In a financial application
+we show that accounting for industry level heterogeneity using the deep model
+improves the accuracy of probabilistic prediction of asset pricing models.",2302.13536v1
+2023-05-03,An identification method for oscillators with response-dependent inertia,"This paper is concerned with identifying the instantaneous modal parameters
+of forced oscillatory systems with response-dependent generalized inertia
+(mass, inductance, or equivalent) based on their measured dynamics. An
+identification method is proposed, which is a variation of the ""FORCEVIB""
+method. The method utilizes analytic signal representation and the properties
+of the Hilbert transform to obtain an analytic relationship between a system's
+natural frequency and damping coefficient to its response and excitation
+signals. The proposed method is validated by comparing the identification
+results to the asymptotic solution of a simple system with response-dependent
+inertia and is then demonstrated, numerically and experimentally, for other
+more complicated nonlinear systems.",2305.02135v2
+2023-05-06,Asymptotic stability of Couette flow in a strong uniform magnetic field for the Euler-MHD system,"In this paper, we prove the asymptotic stability of Couette flow in a strong
+uniform magnetic field for the Euler-MHD system, when the perturbations are in
+Gevrey-$\frac{1}{s}$, $(\frac12<s\leq 1)$ and of size smaller than the
+resistivity coefficient $\mu$. More precisely, we prove (1) the
+$\mu^{-\frac13}$-amplification of the perturbed vorticity, namely, the size of
+the vorticity grows from
+$\|\omega_{\mathrm{in}}\|_{\mathcal{G}^{\lambda_{0}}}\lesssim \mu$ to
+$\|\omega_{\infty}\|_{\mathcal{G}^{\lambda'}}\lesssim \mu^{\frac23}$; (2) the
+polynomial decay of the perturbed current density, namely,
+$\left\|j_{\neq}\right\|_{L^2}\lesssim \frac{c_0 }{\langle t\rangle^2
+}\min\left\{\mu^{-\frac13},\langle t \rangle\right\}$; (3) and the damping for
+the perturbed velocity and magnetic field, namely, \[
+\left\|(u^1_{\neq},b^1_{\neq})\right\|_{L^2}\lesssim \frac{c_0\mu }{\langle
+t\rangle }\min\left\{\mu^{-\frac13},\langle t \rangle\right\}, \quad
+\left\|(u^2,b^2)\right\|_{L^2}\lesssim \frac{c_0\mu }{\langle t\rangle^2
+}\min\left\{\mu^{-\frac13},\langle t \rangle\right\}. \] We also confirm that
+the strong uniform magnetic field stabilizes the Euler-MHD system near Couette
+flow.",2305.04052v1
+2023-05-06,Robust optimization of control parameters for WEC arrays using stochastic methods,"This work presents a new computational optimization framework for the robust
+control of parks of Wave Energy Converters (WEC) in irregular waves. The power
+of WEC parks is maximized with respect to the individual control damping and
+stiffness coefficients of each device. The results are robust with respect to
+the incident wave direction, which is treated as a random variable.
+Hydrodynamic properties are computed using the linear potential model, and the
+dynamics of the system is computed in the frequency domain. A slamming
+constraint is enforced to ensure that the results are physically realistic. We
+show that the stochastic optimization problem is well posed. Two optimization
+approaches for dealing with stochasticity are then considered: stochastic
+approximation and sample average approximation. The outcomes of the above
+mentioned methods in terms of accuracy and computational time are presented.
+The results of the optimization for complex and realistic array configurations
+of possible engineering interest are then discussed. Results of extensive
+numerical experiments demonstrate the efficiency of the proposed computational
+framework.",2305.04130v2
+2023-05-17,Composite operators of stochastic model A,"By means of the field-theoretic renormalization group, we study the damping
+of the viscosity coefficient near the superfluid phase transition. We utilize
+the fact that in the infrared region, the complex model used to describe the
+phase transition belongs to the same universality class as the well-known
+stochastic model A. This allows us a determination of the critical behavior of
+viscosity using composite operators for model A. Our analysis is based on the
+$\varepsilon$-expansion near the upper critical dimension $d_c = 4$ of model A.
+The critical exponent of viscosity is then calculated from the critical
+dimensions of composite operators of massless two-component model A. In
+particular, we present results for critical dimensions of a selected class of
+composite operators with the canonical dimension $8$ to the leading order.",2305.10094v1
+2023-05-30,Gravitational traces of bumblebee gravity in metric-affine formalism,"This work explores various manifestations of bumblebee gravity within the
+metric-affine formalism. We investigate the impact of the Lorentz violation
+parameter, denoted as $X$, on the modification of the Hawking temperature. Our
+calculations reveal that as $X$ increases, the values of the Hawking
+temperature attenuate. To examine the behavior of massless scalar
+perturbations, specifically the quasinormal modes, we employ the WKB method.
+The transmission and reflection coefficients are determined through our
+calculations. The outcomes indicate that a stronger Lorentz-violating parameter
+results in slower damping oscillations of gravitational waves. To comprehend
+the influence of the quasinormal spectrum on time-dependent scattering
+phenomena, we present a detailed analysis of scalar perturbations in the
+time-domain solution. Additionally, we conduct an investigation on shadows,
+revealing that larger values of $X$ correspond to larger shadow radii.
+Furthermore, we constrain the magnitude of the shadow radii using the EHT
+horizon-scale image of $Sgr A^*$. Finally, we calculate both the time delay and
+the deflection angle.",2305.18871v2
+2023-06-22,Global dynamics of a predator-prey model with alarm-taxis,"This paper concerns with the global dynamics of classical solutions to an
+important alarm-taxis ecosystem, which demonstrates the behaviors of prey that
+attract secondary predator when threatened by primary predator. And the
+secondary predator pursues the signal generated by the interaction of the prey
+and primary predator. However, it seems that the necessary gradient estimates
+for global existence cannot be obtained in critical case due to strong coupled
+structure. Thereby, we develop a new approach to estimate the gradient of prey
+and primary predator which takes advantage of slightly higher damping power.
+Then the boundedness of classical solutions in two dimension with Neumann
+boundary conditions can be established by energy estimates and semigroup
+theory. Moreover, by constructing Lyapunov functional, it is proved that the
+coexistence homogeneous steady states is asymptotically stability and the
+convergence rate is exponential under certain assumptions on the system
+coefficients.",2306.12828v1
+2023-07-13,Current status and desired accuracy of the isotopic production cross-sections relevant to astrophysics of cosmic rays II. Fluorine to Silicon (and updated LiBeB),"High-precision cosmic-ray data from ongoing and recent past experiments
+(Voyager, ACE-CRIS, PAMELA, ATIC, CREAM, NUCLEON, AMS-02, CALET, DAMPE) are
+being released in the tens of MeV/n to multi-TeV/n energy range. Astrophysical
+and dark matter interpretations of these data are limited by the precision of
+nuclear production cross-sections. In Paper I, PRC 98, 034611 (2018), we set up
+a procedure to rank nuclear reactions whose desired measurements will enable us
+to fully exploit currently available data on CR Li to N ($Z=3-7$) species. Here
+we extend these rankings to O up to Si nuclei ($Z=8-14$), also updating our
+results on the LiBeB species. We also highlight how comprehensive new high
+precision nuclear data, that could e.g. be obtained at the SPS at CERN, would
+be a game-changer for the determination of key astrophysical quantities
+(diffusion coefficient, halo size of the Galaxy) and indirect searches for dark
+matter signatures.",2307.06798v1
+2023-08-18,Numerical analysis of the Maxwell-Cattaneo-Vernotte nonlinear model,"In the literature, one can find numerous modifications of Fourier's law from
+which the first one is called Maxwell-Cattaneo-Vernotte heat equation. Although
+this model has been known for decades and successfully used to model
+low-temperature damped heat wave propagation, its nonlinear properties are
+rarely investigated. In this paper, we aim to present the functional
+relationship between the transport coefficients and the consequences of their
+temperature dependence. Furthermore, we introduce a particular implicit
+numerical scheme in order to solve such nonlinear heat equations reliably. We
+investigate the scheme's stability, dissipation, and dispersion attributes as
+well. We demonstrate the effect of temperature-dependent thermal conductivity
+on two different initial-boundary value problems, including time-dependent
+boundaries and heterogeneous initial conditions.",2308.09494v1
+2023-08-20,On the Approximation of Operator-Valued Riccati Equations in Hilbert Spaces,"In this work, we present an abstract theory for the approximation of
+operator-valued Riccati equations posed on Hilbert spaces. It is demonstrated
+here, under the assumption of compactness in the coefficient operators, that
+the error of the approximate solution to the operator-valued Riccati equation
+is bounded above by the approximation error of the governing semigroup. One
+significant outcome of this result is the correct prediction of optimal
+convergence for finite element approximations of the operator-valued Riccati
+equations for when the governing semigroup involves parabolic, as well as
+hyperbolic processes. We derive the abstract theory for the time-dependent and
+time-independent operator-valued Riccati equations in the first part of this
+work. In the second part, we prove optimal convergence rates for the finite
+element approximation of the functional gain associated with model
+one-dimensional weakly damped wave and thermal LQR control systems. These
+theoretical claims are then corroborated with computational evidence.",2308.10130v4
+2023-09-14,Where are the Pevatrons that Form the Knee in the Spectrum of the Cosmic Ray Nucleon Component around 4 PeV?,"The paper discusses an approach that made it possible to estimate the
+distance to the nearest pevatrons, which form a knee in the spectrum of the
+cosmic ray nucleon component of about $4$ PeV. It is based on the spectra of
+nucleons and electrons obtained by the authors in the framework of the
+superdiffusion model of nonclassical cosmic rays diffusion, which have a knee,
+on the assumption that nucleons and electrons are accelerated by the same type
+sources and their propagation in an inhomogeneous turbulent galactic medium is
+characterized by the same diffusion coefficient, and also on the knee in the
+spectrum of the electronic component in the region of $0.9$ TeV, established in
+the DAMPE experiment.
+  It is shown that pevatrons, which form a knee in the spectrum of the cosmic
+ray nucleon component of about $4$ PeV, are located at distances of the order
+of $0.75$ kpc from the Earth.",2309.07421v1
+2023-09-25,Magnetism on the thermal dynamics of 2D antiferromagnetic membranes,"We developed a theoretical scheme of incorporating the magnetoelastic
+contribution into the thermal elastic dynamics for the thin membranes of 2D
+antiferromagnetic material with restricted geometry. We extended the elastic
+Gr\""uneisen relation into an effective version which includes the magnetic
+counterpart to the volume change of internal energy. Based on the specific heat
+and thermal conductivity from the elastic and magnetic origins we predicted the
+dependency of observables, such as effective Gr\""uneisen parameter, thermal
+expansion coefficient, and the damping factor, with respect to a wide range of
+temperature across the phase transition. Our model of analysis as been
+validated by applying to the case of FePS3 flake resonator and the theoretical
+predictions fits well with the reported experiment data.",2309.13991v2
+2023-09-27,Stochastic Differential Equation for a System Coupled to a Thermostatic Bath via an Arbitrary Interaction Hamiltonian,"The conventional Langevin equation offers a mathematically convenient
+framework for investigating open stochastic systems interacting with their
+environment or a bath. However, it is not suitable for a wide variety of
+systems whose dynamics rely on the nature of the environmental interaction, as
+the equation does not incorporate any specific information regarding that
+interaction. Here, we present a universal formulation of the stochastic
+differential equation (SDE) for an open system coupled to a thermostatic bath
+via an arbitrary interaction Hamiltonian. This SDE encodes the interaction
+information to a fictitious potential (mean force) and a position-dependent
+damping coefficient. Surprisingly, we find that the conventional Langevin
+equation can be recovered in the presence of arbitrary strong interactions
+given two conditions: translational invariance of the potential and disjoint
+separability of the bath particles. Our results provide a universal framework
+for studying open stochastic systems with an arbitrary interaction Hamiltonian
+and yield deeper insight into why various experiments fit the conventional
+Langevin description regardless of the strength or type of interaction.",2309.15359v1
+2023-09-28,A Lagrangian theory for galaxy shape statistics,"We formulate the Lagrangian perturbation theory of galaxy intrinsic
+alignments and compute the resulting auto and cross power spectra of galaxy
+shapes, densities and matter to 1-loop order. Our model represents a consistent
+effective-theory description of galaxy shape including the resummation of
+long-wavelength displacements which damp baryon acoustic oscillations, and
+includes one linear, three quadratic and two cubic dimensionless bias
+coefficients at this order, along with counterterms and stochastic
+contributions whose structure we derive. We compare this Lagrangian model
+against the three-dimensional helicity spectra of halo shapes measured in
+N-body simulations by Akitsu et al (2023) and find excellent agreement on
+perturbative scales while testing a number of more restrictive bias
+parametrizations. The calculations presented are immediately relevant to
+analyses of both cosmic shear surveys and spectroscopic shape measurements, and
+we make a fast FFTLog-based code spinosaurus publicly available with this
+publication.",2309.16761v2
+2023-10-09,Anomaly and Brownian fluid particle in Navier-Stokes turbulence,"We investigate the Navier-Stokes turbulence driven by a stochastic random
+Gaussian force. Using a field-theoretic approach, we uncover an anomaly that
+brings hidden structure to the theory. The anomaly is generated by a
+non-self-adjoint operator of the Jacobian and it follows the symmetries of the
+stochastic Navier-Stokes equation. We calculate the anomaly and demonstrate
+that by forcing the anomaly to vanish, the velocity field is constrained and a
+monopole-type object with a constant charge is formed. When the viscosity is
+zero, the anomaly can be interpreted as the Brownian damping coefficient of a
+random fluid particle. We provide the Brownian particle equation and its
+solution in the presence of a pump and viscosity. Our results suggest that the
+anomaly is an inherent feature of stochastic turbulence and must be taken into
+account in all stochastic turbulence calculations. This constitutes an
+additional law for the original set of stochastic Navier-Stokes equations.",2310.06007v3
+2023-10-23,Forget metamaterial: It does not improve sound absorption performance as it claims,"The term `sub-wavelength' is commonly used to describe innovative
+sound-absorbing structures usually labeled as `metamaterials'. Such structures,
+however, inherently do not bring groundbreaking advancements. This study
+addresses the limitations imposed by the thickness criterion of Yang et al. by
+introducing the concept of equivalent mass-spring-damping parameters within the
+resonator framework. This innovative approach introduces an index of
+`half-absorption bandwidth' to effectively overcome the thickness restriction.
+Four practical cases are then presented to correct prevalent misleading
+conceptions about low-frequency, broadband absorption as claimed. The
+phenomenon of mass disappearing in the expression of sound absorption
+coefficient supports the conclusion that volume is the only determinant factor
+in sound absorption performance. Any attempts to improve sound absorption
+solely through geometry and structural designs would inevitably sacrifice the
+half-absorption bandwidth. Additionally, the concept of negative stiffness or
+bulk modulus is merely a mathematical convention without any real improvement
+in absorption performance. Overall, this research focuses on the physical
+mechanism of sound-absorbing structures by correcting traditional
+misunderstandings, and offers a comprehensive framework for assessing and
+enhancing sound absorption.",2310.14638v1
+2023-10-30,Optimal control theory for maximum power of Brownian heat engines,"The pursuit of achieving the maximum power in microscopic thermal engines has
+gained increasing attention in recent studies of stochastic thermodynamics. We
+employ the optimal control theory to study the performance of Brownian heat
+engines and determine the optimal heat-engine cycles in generic damped
+situation, which were previously known only in the overdamped and the
+underdamped limits. These optimal cycles include two isothermal processes, two
+adiabatic processes, and an extra isochoric relaxation process at the upper
+stiffness constraint. Our results not only interpolate the optimal cycles
+between the overdamped and the underdamped limits, but also determine the
+appropriate friction coefficient of the Brownian heat engine to achieve the
+maximum power. These findings offer valuable insights for the development of
+high-performance Brownian heat engines in experimental setups.",2310.19622v1
+2023-11-15,On the interaction between compressible inviscid flow and an elastic plate,"We address a free boundary model for the compressible Euler equations where
+the free boundary, which is elastic, evolves according to a weakly damped
+fourth order hyperbolic equation forced by the fluid pressure. This system
+captures the interaction of an inviscid fluid with an elastic plate. We
+establish a priori estimates on local-in-time solutions in low regularity
+Sobolev spaces, namely with velocity and density initial data v0,R0 in H3. The
+main new device is a variable coefficients space tangential-time differential
+operator of order 1 with non-homogeneous boundary conditions, which captures
+the hyperbolic nature of the compressible Euler equations as well as the
+coupling with the structural dynamics.",2311.08731v1
+2023-11-28,Data-Driven Constraints on Cosmic-Ray Diffusion: Probing Self-Generated Turbulence in the Milky Way,"We employ a data-driven approach to investigate the rigidity and spatial
+dependence of the diffusion of cosmic rays in the turbulent magnetic field of
+the Milky Way. Our analysis combines data sets from the experiments Voyager,
+AMS-02, CALET, and DAMPE for a range of cosmic ray nuclei from protons to
+oxygen. Our findings favor models with a smooth behavior in the diffusion
+coefficient, indicating a good qualitative agreement with the predictions of
+self-generated magnetic turbulence models. Instead, the current cosmic-ray data
+do not exhibit a clear preference for or against inhomogeneous diffusion, which
+is also a prediction of these models. Future progress might be possible by
+combining cosmic-ray data with gamma rays or radio observations, enabling a
+more comprehensive exploration.",2311.17150v1
+2023-12-13,Efficient solution of sequences of parametrized Lyapunov equations with applications,"Sequences of parametrized Lyapunov equations can be encountered in many
+application settings. Moreover, solutions of such equations are often
+intermediate steps of an overall procedure whose main goal is the computation
+of quantities of the form $f(X)$ where $X$ denotes the solution of a Lyapunov
+equation. We are interested in addressing problems where the parameter
+dependency of the coefficient matrix is encoded as a low-rank modification to a
+\emph{seed}, fixed matrix. We propose two novel numerical procedures that fully
+exploit such a common structure. The first one builds upon recycling Krylov
+techniques, and it is well-suited for small dimensional problems as it makes
+use of dense numerical linear algebra tools. The second algorithm can instead
+address large-scale problems by relying on state-of-the-art projection
+techniques based on the extended Krylov subspace. We test the new algorithms on
+several problems arising in the study of damped vibrational systems and the
+analyses of output synchronization problems for multi-agent systems. Our
+results show that the algorithms we propose are superior to state-of-the-art
+techniques as they are able to remarkably speed up the computation of accurate
+solutions.",2312.08201v1
+2023-12-24,Resonance effects for linear wave equations with scale invariant oscillating damping,"We consider an abstract linear wave equation with a time-dependent
+dissipation that decays at infinity with the so-called scale invariant rate,
+which represents the critical case. We do not assume that the coefficient of
+the dissipation term is smooth, and we investigate the effect of its
+oscillations on the decay rate of solutions.
+  We prove a decay estimate that holds true regardless of the oscillations.
+Then we show that oscillations that are too fast have no effect on the decay
+rate, while oscillations that are in resonance with one of the frequencies of
+the elastic part can alter the decay rate.
+  In the proof we first reduce ourselves to estimating the decay of solutions
+to a family of ordinary differential equations, then by using polar coordinates
+we obtain explicit formulae for the energy decay of these solutions, so that in
+the end the problem is reduced to the analysis of the asymptotic behavior of
+suitable oscillating integrals.",2312.15531v2
+2024-01-26,Maximum plasmon thermal conductivity of a thin metal film,"Due to their extremely long propagation lengths compared to the wavelengths,
+surface plasmon polaritons (SPPs) have been considered as a key in enhancing
+thermal conductivity in thin metal films. This study explores the conditions at
+which the plasmon thermal conductivity is maximized, considering the
+thickness-dependent metal permittivity. We derived the analytical solutions for
+the plasmon thermal conductivity in both the thin-film and thick-film limits to
+analyze the effect of the permittivities of metals and substrates. From the
+analytical solutions of plasmon thermal conductivity, we deduced that the
+plasmon thermal conductivity is proportional to the electron thermal
+conductivity based on the Wiedemann-Franz law. Additionally, we analyzed the
+conditions where the enhancement ratio of the thermal conductivity via SPPs is
+maximized. Metals with high plasma frequency and low damping coefficient are
+desirable for achieving the maximum plasmon thermal conductivity as well as the
+maximum enhancement ratio of thermal conductivity among metals. Significantly,
+10-cm-long and 14-nm-thick Al film demonstrates most superior in-plane heat
+transfer via SPPs, showing a 53.5\% enhancement in thermal conductivity
+compared to its electron thermal counterpart on a lossless glass substrate.",2401.14677v1
+2024-02-19,Subspace methods for the simulation of molecular response properties on a quantum computer,"We explore Davidson methods for obtaining excitation energies and other
+linear response properties within quantum self-consistent linear response
+(q-sc-LR) theory. Davidson-type methods allow for obtaining only a few selected
+excitation energies without explicitly constructing the electronic Hessian
+since they only require the ability to perform Hessian-vector multiplications.
+We apply the Davidson method to calculate the excitation energies of hydrogen
+chains (up to H$_{10}$) and analyze aspects of statistical noise for computing
+excitation energies on quantum simulators. Additionally, we apply Davidson
+methods for computing linear response properties such as static
+polarizabilities for H$_2$, LiH, H$_2$O, OH$^-$, and NH$_3$, and show that
+unitary coupled cluster outperforms classical projected coupled cluster for
+molecular systems with strong correlation. Finally, we formulate the Davidson
+method for damped (complex) linear response, with application to the nitrogen
+K-edge X-ray absorption of ammonia, and the $C_6$ coefficients of H$_2$, LiH,
+H$_2$O, OH$^-$, and NH$_3$.",2402.12186v1
+2024-03-06,Non-homogeneous anisotropic bulk viscosity for acoustic wave attenuation in weakly compressible methods,"A major limitation of the weakly compressible approaches to simulate
+incompressible flows is the appearance of artificial acoustic waves that
+introduce a large mass conservation error and lead to spurious oscillations in
+the force coefficients. In this work, we propose a non-homogeneous anisotropic
+bulk viscosity term to effectively damp the acoustic waves. By implementing
+this term in a computational framework based on the recently proposed general
+pressure equation, we demonstrate that the non-homogeneous and anisotropic
+nature of the term makes it significantly more effective than the isotropic
+homogeneous version widely used in the literature. Moreover, it is
+computationally more efficient than the pressure (or mass) diffusion term,
+which is an alternative mechanism used to suppress acoustic waves. We simulate
+a range of benchmark problems to comprehensively investigate the performance of
+the bulk viscosity on the effective suppression of acoustic waves, mass
+conservation error, order of convergence of the solver, and computational
+efficiency. The proposed form of the bulk viscosity enables fairly accurate
+modelling of the initial transients of unsteady simulations, which is highly
+challenging for weakly compressible approaches, and to the best of our
+knowledge, existing approaches can't provide an accurate prediction of such
+transients.",2403.03475v1
+2024-03-07,Experimental amplification and squeezing of a motional state of an optically levitated nanoparticle,"A contactless control of fluctuations of phase space variables of a
+nanoobject belongs among the key methods needed for ultra-precise
+nanotechnology and the upcoming quantum technology of macroscopic systems. Here
+we utilize the experimental platform of a single levitating nanoparticle (NP)
+to demonstrate essential protocols providing linear amplification of the
+mechanical phase space variables together with squeezing of phase space
+probability distribution. The protocol combines a controlled fast switching
+between the parabolic trapping potential and either weak parabolic or inverted
+parabolic amplifying potential leading to amplification of mean value and
+variance (fluctuations) along an arbitrary phase space variable and squeezing
+along the complementary one. The protocol is completed with cold damping scheme
+to control the initial fluctuations of the NP phase space variables. We reached
+the amplification gain $|G|>2$, the squeezing coefficient above 4 dB, and the
+second-order energy correlation function approaching 3 which corresponds to a
+maximum for a stochastic non-equilibrium classical state. These experimental
+results will already allow pre-amplification and manipulation of nanomechanical
+NP motion for all quantum protocols if the NP cooling towards the ground state
+is applied.",2403.04302v1
+2024-03-14,Dynamical Friction and Black Holes in Ultralight Dark Matter Solitons,"We numerically simulate the motion of a black hole as it plunges radially
+through an ultralight dark matter soliton. We investigate the timescale in
+which dynamical friction reduces the kinetic energy of the black hole to a
+minimum, and consider the sensitivity of this timescale to changes in the ULDM
+particle mass, the total soliton mass, and the mass of the black hole. We
+contrast our numerical results with a semi-analytic treatment of dynamical
+friction, and find that the latter is poorly suited to this scenario. In
+particular, we find that the back-reaction of the soliton to the presence of
+the black hole is significant, resulting in oscillations in the coefficient of
+dynamical friction which cannot be described in the simple semi-analytical
+framework. Furthermore, we observe a late-time reheating effect, in which a
+significant amount of kinetic energy is transferred back to the black hole
+after an initial damping phase. This complicates the discussion of ULDM
+dynamical friction on the scales relevant to the final parsec problem.",2403.09038v1
+2024-03-21,Partially explicit splitting scheme with explicit-implicit-null method for nonlinear multiscale flow problems,"In this work, we present an efficient approach to solve nonlinear
+high-contrast multiscale diffusion problems. We incorporate the
+explicit-implicit-null (EIN) method to separate the nonlinear term into a
+linear term and a damping term, and then utilise the implicit and explicit time
+marching scheme for the two parts respectively. Due to the multiscale property
+of the linear part, we further introduce a temporal partially explicit
+splitting scheme and construct suitable multiscale subspaces to speed up the
+computation. The approximated solution is splitted into these subspaces
+associated with different physics. The temporal splitting scheme employs
+implicit discretization in the subspace with small dimension that representing
+the high-contrast property and uses explicit discretization for the other
+subspace. We exploit the stability of the proposed scheme and give the
+condition for the choice of the linear diffusion coefficient. The convergence
+of the proposed method is provided. Several numerical tests are performed to
+show the efficiency and accuracy of the proposed approach.",2403.14220v1
+2024-03-13,The q-ary Gilbert-Varshamov bound can be improved for all but finitely many positive integers q,"For any positive integer $q\geq 2$ and any real number $\delta\in(0,1)$, let
+$\alpha_q(n,\delta n)$ denote the maximum size of a subset of $\mathbb{Z}_q^n$
+with minimum Hamming distance at least $\delta n$, where
+$\mathbb{Z}_q=\{0,1,\dotsc,q-1\}$ and $n\in\mathbb{N}$. The asymptotic rate
+function is defined by $ R_q(\delta) =
+\limsup_{n\rightarrow\infty}\frac{1}{n}\log_q\alpha_q(n,\delta n).$ The famous
+$q$-ary asymptotic Gilbert-Varshamov bound, obtained in the 1950s, states that
+\[ R_q(\delta) \geq 1 -
+\delta\log_q(q-1)-\delta\log_q\frac{1}{\delta}-(1-\delta)\log_q\frac{1}{1-\delta}
+\stackrel{\mathrm{def}}{=}R_\mathrm{GV}(\delta,q) \] for all positive integers
+$q\geq 2$ and $0<\delta<1-q^{-1}$. In the case that $q$ is an even power of a
+prime with $q\geq 49$, the $q$-ary Gilbert-Varshamov bound was firstly improved
+by using algebraic geometry codes in the works of Tsfasman, Vladut, and Zink
+and of Ihara in the 1980s. These algebraic geometry codes have been modified to
+improve the $q$-ary Gilbert-Varshamov bound $R_\mathrm{GV}(\delta,q)$ at a
+specific tangent point $\delta=\delta_0\in (0,1)$ of the curve
+$R_\mathrm{GV}(\delta,q)$ for each given integer $q\geq 46$. However, the
+$q$-ary Gilbert-Varshamov bound $R_\mathrm{GV}(\delta,q)$ at $\delta=1/2$,
+i.e., $R_\mathrm{GV}(1/2,q)$, remains the largest known lower bound of
+$R_q(1/2)$ for infinitely many positive integers $q$ which is a generic prime
+and which is a generic non-prime-power integer. In this paper, by using codes
+from geometry of numbers introduced by Lenstra in the 1980s, we prove that the
+$q$-ary Gilbert-Varshamov bound $R_\mathrm{GV}(\delta,q)$ with $\delta\in(0,1)$
+can be improved for all but finitely many positive integers $q$. It is shown
+that the growth defined by $\eta(\delta)=
+\liminf_{q\rightarrow\infty}\frac{1}{\log q}\log[1-\delta-R_q(\delta)]^{-1}$
+for every $\delta\in(0,1)$ has actually a nontrivial lower bound.",2403.08727v2
+2002-06-27,Initial-amplitude dependence in weakly damped oscillators,"A pedagogically instructive experimental procedure is suggested for
+distinguishing between different damping terms in a weakly damped oscillator,
+which highclights the connection between non-linear damping and
+initial-amplitude dependence. The most common damping terms such as contact
+friction, air resistance, viscous drag, and electromagnetic damping have
+velocity dependences of the form constant, v, or v^2. The corresponding energy
+dependences of the form \sqrt{E}, E, or E\sqrt{E} in the energy loss equation
+give rise to characteristic dependence of the amplitude decay slope on the
+initial amplitude.",0206086v1
+2006-05-22,The entanglement of damped noon-state and its performance in phase measurement,"The state evolution of the initial optical \textit{noon} state is
+investigated. The residue entanglement of the state is calculated after it is
+damped by amplitude and phase damping. The relative entropy of entanglement of
+the damped state is exactly obtained. The performance of direct application of
+the damped \textit{noon} state is compared with that of firstly distilling the
+docoherence damped state then applying it in measurement.",0605184v1
+2007-10-04,Channel-Adapted Quantum Error Correction for the Amplitude Damping Channel,"We consider error correction procedures designed specifically for the
+amplitude damping channel. We analyze amplitude damping errors in the
+stabilizer formalism. This analysis allows a generalization of the [4,1]
+`approximate' amplitude damping code of quant-ph/9704002. We present this
+generalization as a class of [2(M+1),M] codes and present quantum circuits for
+encoding and recovery operations. We also present a [7,3] amplitude damping
+code based on the classical Hamming code. All of these are stabilizer codes
+whose encoding and recovery operations can be completely described with
+Clifford group operations. Finally, we describe optimization options in which
+recovery operations may be further adapted according to the damping probability
+gamma.",0710.1052v1
+2010-03-24,Dynamical shift condition for unequal mass black hole binaries,"Certain numerical frameworks used for the evolution of binary black holes
+make use of a gamma driver, which includes a damping factor. Such simulations
+typically use a constant value for damping. However, it has been found that
+very specific values of the damping factor are needed for the calculation of
+unequal mass binaries. We examine carefully the role this damping plays, and
+provide two explicit, non-constant forms for the damping to be used with
+mass-ratios further from one. Our analysis of the resultant waveforms compares
+well against the constant damping case.",1003.4681v1
+2011-11-30,Local phase damping of single qubits sets an upper bound on the phase damping rate of entangled states,"I derive an inequality in which the phase damping rates of single qubits set
+an upper bound for the phase damping rate of entangled states of many qubits.
+The derivation is based on two assumptions: first, that the phase damping can
+be described by a dissipator in Lindblad form and, second, that the phase
+damping preserves the population of qubit states in a given basis.",1111.7152v2
+2012-05-11,Quantum dynamics of the damped harmonic oscillator,"The quantum theory of the damped harmonic oscillator has been a subject of
+continual investigation since the 1930s. The obstacle to quantization created
+by the dissipation of energy is usually dealt with by including a discrete set
+of additional harmonic oscillators as a reservoir. But a discrete reservoir
+cannot directly yield dynamics such as Ohmic damping (proportional to velocity)
+of the oscillator of interest. By using a continuum of oscillators as a
+reservoir, we canonically quantize the harmonic oscillator with Ohmic damping
+and also with general damping behaviour. The dynamics of a damped oscillator is
+determined by an arbitrary effective susceptibility that obeys Kramers-Kronig
+relations. This approach offers an alternative description of nano-mechanical
+oscillators and opto-mechanical systems.",1205.2545v1
+2014-02-28,Escape rate for the power-law distribution in low-to-intermediate damping,"Escape rate in the low-to-intermediate damping connecting the low damping
+with the intermediate damping is established for the power-law distribution on
+the basis of flux over population theory. We extend the escape rate in the low
+damping to the low-to-intermediate damping, and get an expression for the
+power-law distribution. Then we apply the escape rate for the power-law
+distribution to the experimental study of the excited-state isomerization, and
+show a good agreement with the experimental value. The extra current and the
+improvement of the absorbing boundary condition are discussed.",1402.7194v2
+2015-03-21,On damping created by heterogeneous yielding in the numerical analysis of nonlinear reinforced concrete frame elements,"In the dynamic analysis of structural engineering systems, it is common
+practice to introduce damping models to reproduce experimentally observed
+features. These models, for instance Rayleigh damping, account for the damping
+sources in the system altogether and often lack physical basis. We report on an
+alternative path for reproducing damping coming from material nonlinear
+response through the consideration of the heterogeneous character of material
+mechanical properties. The parameterization of that heterogeneity is performed
+through a stochastic model. It is shown that such a variability creates the
+patterns in the concrete cyclic response that are classically regarded as
+source of damping.",1503.07122v1
+2016-01-20,Introduction to Landau Damping,"The mechanism of Landau damping is observed in various systems from plasma
+oscillations to accelerators. Despite its widespread use, some confusion has
+been created, partly because of the different mechanisms producing the damping
+but also due to the mathematical subtleties treating the effects. In this
+article the origin of Landau damping is demonstrated for the damping of plasma
+oscillations. In the second part it is applied to the damping of coherent
+oscillations in particle accelerators. The physical origin, the mathematical
+treatment leading to the concept of stability diagrams and the applications are
+discussed.",1601.05227v1
+2018-07-25,Regularity and asymptotic behaviour for a damped plate-membrane transmission problem,"We consider a transmission problem where a structurally damped plate equation
+is coupled with a damped or undamped wave equation by transmission conditions.
+We show that exponential stability holds in the damped-damped situation and
+polynomial stability (but no exponential stability) holds in the
+damped-undamped case. Additionally, we show that the solutions first defined by
+the weak formulation, in fact have higher Sobolev space regularity.",1807.09730v1
+2002-11-03,Damping of coupled phonon--plasmon modes,"The effect of free carriers on dispersion and damping of coupled
+phonon-plasmon modes is considered in the long-wave approximation. The electron
+and phonon scattering rate as well as Landau damping are taken into account.",0211040v1
+2002-02-01,"On ""the authentic damping mechanism"" of the phonon damping model","Some general features of the phonon damping model are presented. It is
+concluded that the fits performed within this model have no physical content.",0202006v1
+2018-01-28,Observations of excitation and damping of transversal oscillation in coronal loops by AIA/SDO,"The excitation and damping of transversal coronal loop oscillations and
+quantitative relation between damping time, damping quality (damping time per
+period), oscillation amplitude, dissipation mechanism and the wake phenomena
+are investigated. The observed time series data with the \textit{Atmospheric
+Imaging Assembly} (AIA) telescope on NASA's \textit{Solar Dynamics Observatory}
+(SDO) satellite on 2015 March 2, consisting of 400 consecutive images with 12
+seconds cadence in the 171 $ \rm{{\AA}}$ pass band is analyzed for evidence of
+transversal oscillations along the coronal loops by Lomb-Scargle periodgram. In
+this analysis signatures of transversal coronal loop oscillations that are
+damped rapidly were found with dominant oscillation periods in the range of
+$\rm{P=12.25-15.80}$ minutes. Also, damping times and damping qualities of
+transversal coronal loop oscillations at dominant oscillation periods are
+estimated in the range of $ \rm{\tau_d=11.76-21.46}$ minutes and $
+\rm{\tau_d/P=0.86-1.49}$, respectively. The observational results of this
+analysis show that damping qualities decrease slowly with increasing the
+amplitude of oscillation, but periods of oscillations are not sensitive
+function of amplitude of oscillations. The order of magnitude of the damping
+qualities and damping times are in good agreement with previous findings and
+the theoretical prediction for damping of kink mode oscillations by dissipation
+mechanism. Furthermore, oscillation of loop segments attenuate with time
+roughly as $t^{-\alpha}$ that magnitude values of $\alpha$ for 30 different
+segments change from 0.51 to 0.75.",1801.09217v1
+1999-11-16,Probing supernovae ejecta by Halpha damping wings,"It is predicted that H$\alpha$ emission line at the early nebular epoch of
+type II-P supernovae may display robust observational effects of damping wings.
+This is illustrated by Monte-Carlo simulations. The strength of damping wing
+effects may be used to constrain parameters of the line-emitting zone. An
+anomalous redshift, width and red wing of H$\alpha$ revealed by SN 1997D on day
+150 are explained in terms of damping wing effects.",9911300v1
+2009-01-23,Rheological Interpretation of Rayleigh Damping,"Damping is defined through various terms such as energy loss per cycle (for
+cyclic tests), logarithmic decrement (for vibration tests), complex modulus,
+rise-time or spectrum ratio (for wave propagation analysis), etc. For numerical
+modeling purposes, another type of damping is frequently used : it is called
+Rayleigh damping. It is a very convenient way of accounting for damping in
+numerical models, although the physical or rheological meaning of this approach
+is not clear. A rheological model is proposed to be related to classical
+Rayleigh damping : it is a generalized Maxwell model with three parameters. For
+moderate damping (<25%), this model perfectly coincide with Rayleigh damping
+approach since internal friction has the same expression in both cases and
+dispersive phenomena are negligible. This is illustrated by finite element
+(Rayleigh damping) and analytical (generalized Maxwell model) results in a
+simple one-dimensional case.",0901.3717v1
+2009-05-20,"Eigenvalue asymptotics, inverse problems and a trace formula for the linear damped wave equation","We determine the general form of the asymptotics for Dirichlet eigenvalues of
+the one-dimensional linear damped wave operator. As a consequence, we obtain
+that given a spectrum corresponding to a constant damping term this determines
+the damping term in a unique fashion. We also derive a trace formula for this
+problem.",0905.3242v1
+2015-05-06,Remarks on the asymptotic behavior of the solution of an abstract damped wave equation,"We study an abstract damped wave equation. We prove that the solution of the
+damped wave equation becomes closer to the solution of a heat type equation as
+time tend to infinity. As an application of our approach, we also study the
+asymptotic behavior of the damped wave equation in Euclidean space under the
+geometric control condition.",1505.01794v2
+2017-01-18,Two types of spurious damping forces potentially modeled in numerical seismic nonlinear response history analysis,"The purpose of this paper is to provide practitioners with further insight
+into spurious damping forces that can be generated in nonlinear seismic
+response history analyses (RHA). The term 'spurious' is used to refer to
+damping forces that are not present in an elastic system and appear as
+nonlinearities develop: such damping forces are not necessarily intended and
+appear as a result of modifications in the structural properties as it yields
+or damages due to the seismic action. In this paper, two types of spurious
+damping forces are characterized. Each type has often been treated separately
+in the literature, but each has been qualified as 'spurious', somehow blurring
+their differences. Consequently, in an effort to clarify the consequences of
+choosing a particular viscous damping model for nonlinear RHA, this paper shows
+that damping models that avoid spurious damping forces of one type do not
+necessarily avoid damping forces of the other type.",1701.05092v1
+2017-02-02,Exponential stability for a coupled system of damped-undamped plate equations,"We consider the transmission problem for a coupled system of undamped and
+structurally damped plate equations in two sufficiently smooth and bounded
+subdomains. It is shown that, independently of the size of the damped part, the
+damping is strong enough to produce uniform exponential decay of the energy of
+the coupled system.",1702.00637v1
+2017-09-11,Comparison of damping mechanisms for transverse waves in solar coronal loops,"We present a method to assess the plausibility of alternative mechanisms to
+explain the damping of magnetohydrodynamic (MHD) transverse waves in solar
+coronal loops. The considered mechanisms are resonant absorption of kink waves
+in the Alfv\'en continuum, phase-mixing of Alfv\'en waves, and wave leakage.
+Our methods make use of Bayesian inference and model comparison techniques. We
+first infer the values for the physical parameters that control the wave
+damping, under the assumption of a particular mechanism, for typically observed
+damping time-scales. Then, the computation of marginal likelihoods and Bayes
+factors enable us to quantify the relative plausibility between the alternative
+mechanisms. We find that, in general, the evidence is not large enough to
+support a single particular damping mechanism as the most plausible one.
+Resonant absorption and wave leakage offer the most probable explanations in
+strong damping regimes, while phase mixing is the best candidate for
+weak/moderate damping. When applied to a selection of 89 observed transverse
+loop oscillations, with their corresponding measurements of damping times
+scales and taking into account data uncertainties, we find that only in a few
+cases positive evidence for a given damping mechanism is available.",1709.03347v1
+2019-03-25,Distributed Inter-Area Oscillation Damping Control for Power Systems by Using Wind Generators and Load Aggregators,"This paper investigates the potential of wind turbine generators (WTGs) and
+load aggregators (LAs) to provide supplementary damping control services for
+low frequency inter-area oscillations (LFOs) through the additional distributed
+damping control units (DCUs) proposed in their controllers. In order to provide
+a scalable methodology for the increasing number of WTGs and LAs, a novel
+distributed control framework is proposed to coordinate damping controllers.
+Firstly, a distributed algorithm is designed to reconstruct the system Jacobian
+matrix for each damping bus (buses with damping controllers). Thus, the
+critical LFO can be identified locally at each damping bus by applying
+eigen-analysis to the obtained system Jacobian matrix. Then, if the damping
+ratio of the critical LFO is less than a preset threshold, the control
+parameters of DCUs will be tuned in a distributed and coordinated manner to
+improve the damping ratio and minimize the total control cost at the same time.
+The proposed control framework is tested in a modified IEEE 39-bus test system.
+The simulation results with and without the proposed control framework are
+compared to demonstrate the effectiveness of the proposed framework.",1903.10135v1
+2020-12-05,On Periodical Damping Ratio of a Controlled Dynamical System with Parametric Resonances,"This report provides an interpretation on the periodically varying damping
+ratio of a dynamical system with direct control of oscillation or vibration
+damping. The principal parametric resonance of the system and a new type of
+parametric resonance, named ""zero-th order"" parametric resonance, are
+investigated by using the method of multiple scales to find approximate,
+analytical solutions of the system, which provide an interpretation on such
+damping variations.",2012.02932v1
+2021-06-22,Sharp decay rate for the damped wave equation with convex-shaped damping,"We revisit the damped wave equation on two-dimensional torus where the damped
+region does not satisfy the geometric control condition. We show that if the
+damping vanishes as a H\""older function $|x|^{\beta}$, and in addition, the
+boundary of the damped region is strictly convex, the wave is stable at rate
+$t^{-1+\frac{2}{2\beta+7}}$, which is better than the known optimal decay rate
+$t^{-1+\frac{1}{\beta+3}}$ for strip-shaped dampings of the same H\""older
+regularity. Moreover, we show by example that the decay rate is optimal. This
+illustrates the fact that the energy decay rate depends not only on the order
+of vanishing of the damping, but also on the shape of the damped region. The
+main ingredient of the proof is the averaging method (normal form reduction)
+developed by Hitrick and Sj\""ostrand (\cite{Hi1}\cite{Sj}).",2106.11782v3
+2021-08-09,Effect of stepwise adjustment of Damping factor upon PageRank,"The effect of adjusting damping factor {\alpha}, from a small initial value
+{\alpha}0 to the final desired {\alpha}f value, upon then iterations needed for
+PageRank computation is observed. Adjustment of the damping factor is done in
+one or more steps. Results show no improvement in performance over a fixed
+damping factor based PageRank.",2108.04150v1
+2021-08-17,"Asymptotic behaviour of the wave equation with nonlocal weak damping, anti-damping and critical nonlinearity","In this paper we prove the existence of the global attractor for the wave
+equation with nonlocal weak damping, nonlocal anti-damping and critical
+nonlinearity.",2108.07395v2
+1997-11-20,Symmetric matrices and quantum codes,"This paper has been withdrawn since a Gilbert-Varshamov bound for general
+quantum codes has already appeared in Ekert and Macchiavello, Prys. Rev. Lett.
+77, p. 2585, and a Gilbert-Varshamov bound for stabilizer codes connected with
+orthogonal geometry, or equivalently, with symmetric matrices as in this paper,
+has been proved by Calredbank, Rains, Shor and Sloane, Phys. Rev. Lett. 78, p.
+405. I would like to thank Robert Calderbank for pointing out these references
+to me.",9711026v2
+1994-06-09,Black Holes from Blue Spectra,"Blue primordial power spectra with a spectral index $n>1$ can lead to a
+significant production of primordial black holes in the very early Universe.
+The evaporation of these objects leads to a number of observational
+consequences and a model independent upper limit of $n \approx 1.4$. In some
+cases this limit is strengthened to $n=1.3$. Such limits may be employed to
+define the boundary to the region of parameter space consistent with
+generalized inflationary predictions. [To appear in Proceedings of the CASE
+WESTERN CMB WORKSHOP, April 22-24 1994. Figures available on request from
+J.H.Gilbert@qmw.ac.uk]",9406028v1
+1995-06-14,Inversions in astronomy and the SOLA method,"This paper was presented at the Institute for Mathematics and its
+Applications workshop ""Inverse problems in wave propagation"" and will appear in
+the series IMA volumes (Springer). A brief overview of applications of
+inversions within astronomy is presented and also an inventory of techniques
+commonly in use. Most of this paper is focussed on the method of Subtractive
+Optimally Localized Averages (SOLA) which is an adaptation of the Backus and
+Gilbert method. This method was originally developed for use in helioseismology
+where the Backus and Gilbert method is computationally too slow. Since then it
+has also been applied to the problem of reverberation mapping of active
+galactic nuclei and the differences between this inverse problem and the ones
+of helioseismology are also discussed.",9506084v1
+1997-11-11,No Need for MACHOS in the Halo,"A simple interpretation of the more than dozen microlensing events seen in
+the direction of the LMC is a halo population of MACHOs which accounts for
+about half of the mass of the Galaxy. Such an interpretation is not without its
+problems, and we show that current microlensing data can, with some advantage,
+be explained by dark components of the disk and spheroid, whose total mass is
+only about 10% of the mass of the Galaxy.",9711110v1
+2006-02-11,Likelihood Functions for Galaxy Cluster Surveys,"Galaxy cluster surveys offer great promise for measuring cosmological
+parameters, but survey analysis methods have not been widely studied. Using
+methods developed decades ago for galaxy clustering studies, it is shown that
+nearly exact likelihood functions can be written down for galaxy cluster
+surveys. The sparse sampling of the density field by galaxy clusters allows
+simplifications that are not possible for galaxy surveys. An application to
+counts in cells is explicitly tested using cluster catalogs from numerical
+simulations and it is found that the calculated probability distributions are
+very accurate at masses above several times 10^{14}h^{-1} solar masses at z=0
+and lower masses at higher redshift.",0602251v3
+2000-03-25,Thermokinetic approach of the generalized Landau-Lifshitz-Gilbert equation with spin polarized current,"In order to describe the recently observed effect of current induced
+magnetization reversal in magnetic nanostructures, the thermokinetic theory is
+applied to a metallic ferromagnet in contact with a reservoir of spin polarized
+conduction electrons. The spin flip relaxation of the conduction electrons is
+described thermodynamically as a chemical reaction. The diffusion equation of
+the chemical potential (or the giant magnetoresistance) and the usual
+Landau-Lifshitz-Gilbert (LLG) equation are derived from the entropy variation.
+The expression of the conservation laws of the magnetic moments, including spin
+dependent scattering processes, leads then to the generalized LLG equation with
+spin polarized current. The equation is applied to the measurements obtained on
+single magnetic Ni nanowires.",0003409v1
+2004-05-26,Nonequilibrium Extension of the Landau-Lifshitz-Gilbert Equation for Magnetic Systems,"Using the invariant operator method for an effective Hamiltonian including
+the radiation-spin interaction, we describe the quantum theory for
+magnetization dynamics when the spin system evolves nonadiabatically and out of
+equilibrium, $d \hat{\rho}/dt \neq 0$. It is shown that the vector parameter of
+the invariant operator and the magnetization defined with respect to the
+density operator, both satisfying the quantum Liouville equation, still obey
+the Landau-Lifshitz-Gilbert equation.",0405599v1
+2006-10-16,Properties of Codes with the Rank Metric,"In this paper, we study properties of rank metric codes in general and
+maximum rank distance (MRD) codes in particular. For codes with the rank
+metric, we first establish Gilbert and sphere-packing bounds, and then obtain
+the asymptotic forms of these two bounds and the Singleton bound. Based on the
+asymptotic bounds, we observe that asymptotically Gilbert-Varsharmov bound is
+exceeded by MRD codes and sphere-packing bound cannot be attained. We also
+establish bounds on the rank covering radius of maximal codes, and show that
+all MRD codes are maximal codes and all the MRD codes known so far achieve the
+maximum rank covering radius.",0610099v2
+1994-08-26,On the Dirichlet problem for harmonic maps with prescribed singularities,"Let $\M$ be a classical Riemannian globally symmetric space of rank one and
+non-compact type. We prove the existence and uniqueness of solutions to the
+Dirichlet problem for harmonic maps into $\M$ with prescribed singularities
+along a closed submanifold of the domain. This generalizes our previous work
+where such maps into the hyperbolic plane were constructed. This problem, in
+the case where $\M$ is the complex-hyperbolic plane, has applications to
+equilibrium configurations of co-axially rotating charged black holes in
+General Relativity.",9408005v1
+1997-08-15,One-Loop Minimization Conditions in the Minimal Supersymmetric Standard Model,"We study, in the Minimal Supersymmetric Standard Model, the electroweak
+symmetry breaking conditions obtained from the one-loop effective potential.
+Novel model-independent lower and upper bounds on $\tan \beta$, involving the
+other free parameters of the model, are inferred and determined analytically.
+We discuss briefly some of the related issues and give an outlook for further
+applications.",9708368v1
+2004-05-31,On a Penrose Inequality with Charge,"We construct a time-symmetric asymptotically flat initial data set to the
+Einstein-Maxwell Equations which satisfies the inequality: m - 1/2(R + Q^2/R) <
+0, where m is the total mass, R=sqrt(A/4) is the area radius of the outermost
+horizon and Q is the total charge. This yields a counter-example to a natural
+extension of the Penrose Inequality to charged black holes.",0405602v3
+2004-07-26,Automorphisms of free groups have asymptotically periodic dynamics,"We show that every automorphism $\alpha$ of a free group $F_k$ of finite rank
+$k$ has {\it asymptotically periodic} dynamics on $F_k$ and its boundary
+$\partial F_k$: there exists a positive power $\alpha^q$ such that every
+element of the compactum $F_k \cup \partial F_k$ converges to a fixed point
+under iteration of $\alpha^q$.",0407437v2
+2004-12-30,The Construction of a Partially Regular Solution to the Landau-Lifshitz-Gilbert Equation in $\mathbb{R}^2$,"We establish a framework to construct a global solution in the space of
+finite energy to a general form of the Landau-Lifshitz-Gilbert equation in
+$\mathbb{R}^2$. Our characterization yields a partially regular solution,
+smooth away from a 2-dimensional locally finite Hausdorff measure set. This
+construction relies on approximation by discretization, using the special
+geometry to express an equivalent system whose highest order terms are linear
+and the translation of the machinery of linear estimates on the fundamental
+solution from the continuous setting into the discrete setting. This method is
+quite general and accommodates more general geometries involving targets that
+are compact smooth hypersurfaces.",0412534v1
+2002-01-13,Inverse Cascade Regime in Shell Models of 2-Dimensional Turbulence,"We consider shell models that display an inverse energy cascade similar to
+2-dimensional turbulence (together with a direct cascade of an enstrophy-like
+invariant). Previous attempts to construct such models ended negatively,
+stating that shell models give rise to a ""quasi-equilibrium"" situation with
+equipartition of the energy among the shells. We show analytically that the
+quasi-equilibrium state predicts its own disappearance upon changing the model
+parameters in favor of the establishment of an inverse cascade regime with K41
+scaling. The latter regime is found where predicted, offering a useful model to
+study inverse cascades.",0201020v1
+2002-04-23,Algebraic decay in hierarchical graphs,"We study the algebraic decay of the survival probability in open hierarchical
+graphs. We present a model of a persistent random walk on a hierarchical graph
+and study the spectral properties of the Frobenius-Perron operator. Using a
+perturbative scheme, we derive the exponent of the classical algebraic decay in
+terms of two parameters of the model. One parameter defines the geometrical
+relation between the length scales on the graph, and the other relates to the
+probabilities for the random walker to go from one level of the hierarchy to
+another. The scattering resonances of the corresponding hierarchical quantum
+graphs are also studied. The width distribution shows the scaling behavior
+$P(\Gamma) \sim 1/\Gamma$.",0204056v1
+2004-03-11,Statistics of active vs. passive advections in magnetohydrodynamic turbulence,"Active turbulent advection is considered in the context of
+magneto-hydrodynamics. In this case, an auxiliary passive field bears no
+apparent connection to the active field. The scaling properties of the two
+fields are different. In the framework of a shell model, we show that the
+two-point structure function of the passive field has a unique zero mode,
+characterizing the scaling of this field only. In other words, the existence of
+statistical invariants for the decaying passive field carries no information on
+the scaling properties of the active field.",0403017v1
+2006-01-19,Drift of particles in self-similar systems and its Liouvillian interpretation,"We study the dynamics of classical particles in different classes of
+spatially extended self-similar systems, consisting of (i) a self-similar
+Lorentz billiard channel, (ii) a self-similar graph, and (iii) a master
+equation. In all three systems the particles typically drift at constant
+velocity and spread ballistically. These transport properties are analyzed in
+terms of the spectral properties of the operator evolving the probability
+densities. For systems (i) and (ii), we explain the drift from the properties
+of the Pollicott-Ruelle resonance spectrum and corresponding eigenvectors",0601042v1
+1997-11-20,Quantum self-dual codes and symmetric matrices,"This paper has been withdrawn since a Gilbert-Varshamov bound for general
+quantum codes has already appeared in Ekert and Macchiavello, Prys. Rev. Lett.
+77, p. 2585, and a Gilbert-Varshamov bound for stabilizer codes connected with
+orthogonal geometry, or equivalently, with symmetric matrices as in this paper,
+has been proved by Calredbank, Rains, Shor and Sloane, Phys. Rev. Lett. 78, p.
+405. I would like to thank Robert Calderbank for pointing out these references
+to me.",9711047v2
+2001-06-06,Constraints on Eavesdropping on the BB84 Protocol,"An undetected eavesdropping attack must produce count rate statistics that
+are indistinguishable from those that would arise in the absence of such an
+attack. In principle this constraint should force a reduction in the amount of
+information available to the eavesdropper. In this paper we illustrate, by
+considering a particular class of eavesdropping attacks, how the general
+analysis of this problem may proceed.",0106034v2
+2007-09-14,A complete proof of The Graceful Tree Conjecture using the concept of Edge Degree,We show the Graceful Tree Conjecture holds.,0709.2201v9
+2007-09-24,An extension of a result concerning convex geometric graphs,"We show a general result known as the Erdos_Sos Conjecture: if
+$E(G)>{1/2}(k-1)n$ where $G$ has order $n$ then $G$ contains every tree of
+order $k+1$ as a subgraph.",0709.3590v5
+2008-06-13,Heat conduction and Fourier's law by consecutive local mixing and thermalization,"We present a first-principles study of heat conduction in a class of models
+which exhibit a new multi-step local thermalization mechanism which gives rise
+to Fourier's law. Local thermalization in our models occurs as the result of
+binary collisions among locally confined gas particles. We explore the
+conditions under which relaxation to local equilibrium, which involves no
+energy exchange, takes place on time scales shorter than that of the binary
+collisions which induce local thermalization. The role of this mechanism in
+multi-phase material systems such as aerogels is discussed.",0806.2193v1
+2010-04-09,Strict inequalities of critical probabilities on Gilbert's continuum percolation graph,"Any infinite graph has site and bond percolation critical probabilities
+satisfying $p_c^{site}\geq p_c^{bond}$. The strict version of this inequality
+holds for many, but not all, infinite graphs.
+  In this paper, the class of graphs for which the strict inequality holds is
+extended to a continuum percolation model. In Gilbert's graph with
+supercritical density on the Euclidean plane, there is almost surely a unique
+infinite connected component. We show that on this component $p_c^{site} >
+p_c^{bond}$. This also holds in higher dimensions.",1004.1596v2
+2010-04-15,Rank of mapping tori and companion matrices,"Given $f$ in $GL(d,Z)$, it is decidable whether its mapping torus (the
+semi-direct product of $Z^d$ with $Z$) may be generated by two elements or not;
+if so, one can classify generating pairs up to Nielsen equivalence. If $f$ has
+infinite order, the mapping torus of $f^n$ cannot be generated by two elements
+for $n$ large enough; equivalently, $f^n$ is not conjugate to a companion
+matrix in $GL(d,Z)$ if $n$ is large.",1004.2649v1
+2010-04-30,Limit theory for planar Gilbert tessellations,"A Gilbert tessellation arises by letting linear segments (cracks) in the
+plane unfold in time with constant speed, starting from a homogeneous Poisson
+point process of germs in randomly chosen directions. Whenever a growing edge
+hits an already existing one, it stops growing in this direction. The resulting
+process tessellates the plane. The purpose of the present paper is to establish
+law of large numbers, variance asymptotics and a central limit theorem for
+geometric functionals of such tessellations. The main tool applied is the
+stabilization theory for geometric functionals.",1005.0023v1
+2010-06-24,Periodic solutions for the Landau-Lifshitz-Gilbert equation,"Ferromagnetic materials tend to develop very complex magnetization patterns
+whose time evolution is modeled by the so-called Landau-Lifshitz-Gilbert
+equation (LLG). In this paper, we construct time-periodic solutions for LLG in
+the regime of soft and small ferromagnetic particles which satisfy a certain
+shape condition. Roughly speaking, it is assumed that the length of the
+particle is greater than its hight and its width. The approach is based on a
+perturbation argument and the spectral analysis of the corresponding linearized
+problem as well as the theory of sectorial operators.",1006.4765v1
+2010-12-19,A counterexample to a Penrose inequality conjectured by Gibbons,"We show that the Brill-Lindquist initial data provides a counterexample to a
+Riemannian Penrose inequality with charge conjectured by G. Gibbons. The
+observation illustrates a sub-additive characteristic of the area radii for the
+individual connected components of an outermost horizon as a lower bound of the
+ADM mass.",1012.4190v2
+2012-01-12,Coil-helix transition in poly(L-glutamic acid) : Evidence for a 3-state non-cooperative process,"A careful analysis of measurements of circular dichroism of poly(L-glutamic
+acid) (PGA) shows that the data can be very accurately described by introducing
+a third state for the PGA configuration, in addition to the helix and coil
+ones, and considering a simple equilibrium between these three states, without
+cooperativity. The third state is more conspicuous when high molecular weight
+polyethyleneglycol (PEG) is added. Excluded volume effects shown by differences
+in presence of short and long PEG chains indicate a direct interaction of PEG
+and PGA rather than an osmotic effect.",1201.2566v1
+2012-03-20,Vortex dynamics in the presence of excess energy for the Landau-Lifschitz-Gilbert equation,"We study the Landau-Lifshitz-Gilbert equation for the dynamics of a magnetic
+vortex system. We present a PDE-based method for proving vortex dynamics that
+does not rely on strong well-preparedness of the initial data and allows for
+instantaneous changes in the strength of the gyrovector force due to bubbling
+events. The main tools are estimates of the Hodge decomposition of the
+supercurrent and an analysis of the defect measure of weak convergence of the
+stress energy tensor. Ginzburg-Landau equations with mixed dynamics in the
+presence of excess energy are also discussed.",1203.4426v1
+2012-12-22,Cumulative Distance Enumerators of Random Codes and their Thresholds,"Cumulative weight enumerators of random linear codes are introduced, their
+asymptotic properties are studied, and very sharp thresholds are exhibited; as
+a consequence, it is shown that the asymptotic Gilbert-Varshamov bound is a
+very sharp threshold point for the density of the linear codes whose relative
+distance is greater than a given positive number. For arbitrary random codes,
+similar settings and results are exhibited; in particular, the very sharp
+threshold point for the density of the codes whose relative distance is greater
+than a given positive number is located at half the asymptotic
+Gilbert-Varshamov bound.",1212.5679v1
+2013-01-23,The Importance of Continuous Value Based Project Management in the Context of Requirements Engineering,"Despite several scientific achievements in the last years, there are still a
+lot of IT projects that fail. Researchers found that one out of five
+IT-projects run out of time, budget or value. Major reasons for this failure
+are unexpected economic risk factors that emerge during the runtime of
+projects. In order to be able to identify emerging risks early and to
+counteract reasonably, financial methods for a continuous IT-project-steering
+are necessary, which as of today to the best of our knowledge are missing
+within scientific literature.",1301.5438v1
+2013-04-08,On Automorphisms and Subtowers of an asymptotically optimal Tower of Function Fields,"In this article we investigate the automorphism group of an asymptotically
+optimal tower of function fields introduced by Garcia and Stichtenoth. In
+particular we provide a detailed description of the decomposition group of some
+rational places. This group acts on the algebraic-geometric standard codes
+obtained by the Garcia-Stichtenoth tower exceeding the Gilbert-Varshamov bound.
+The fields fixed by the decomposition groups form an asymptotically optimal
+non-Galois subtower, which has been first found by Bezerra and Garcia and
+yields an improvement for computing codes above the Gilbert-Varshamov bound. In
+this article we also describe its proportionality to the Garcia-Stichtenoth
+tower and obtain new precise results on its rational places and their
+Weierstra{\ss} semigroups.",1304.2145v1
+2013-05-06,The Moment Generating function for ray lengths in the Half Gilbert Model with Rectangular Cells,"In the full rectangular version of Gilbert's tessellation lines extend either
+horizontally (with east- and west--growing rays) or vertically (north- and
+south--growing rays) from seed points which form a Poisson point process, each
+ray stopping when another ray is met. In the half rectangular version, east and
+south growing rays do not interact with west and north rays. Using techniques
+developed in our previous paper, we derive an exact expression for the moment
+generating function for the ray length distribution in the half rectangular
+model.",1305.1289v1
+2013-07-15,Degenerate transition pathways for screw dislocations: implications for migration,"In body-centred-cubic (bcc) metals migrating 1/2<111> screw dislocations
+experience a periodic energy landscape with a triangular symmetry. Atomistic
+simulations, such as those performed using the nudged-elastic-band (NEB)
+method, generally predict a transition-pathway energy-barrier with a
+double-hump; contradicting Ab Initio findings. Examining the trajectories
+predicted by NEB for a particle in a Peierls energy landscape representative of
+that obtained for a screw dislocation, reveals an unphysical anomaly caused by
+the occurrence of monkey saddles in the landscape. The implications for motion
+of screws with and without stress are discussed.",1307.3848v2
+2013-08-17,The Riemannian Penrose Inequality with Charge for Multiple Black Holes,"We present a proof of the Riemannian Penrose inequality with charge $r\leq m
++ \sqrt{m^2-q^2}$, where $A=4\pi r^2$ is the area of the outermost apparent
+horizon with possibly multiple connected components, $m$ is the total ADM mass,
+and $q$ the total charge of a strongly asymptotically flat initial data set for
+the Einstein-Maxwell equations, satisfying the charged dominant energy
+condition, with no charged matter outside the horizon.",1308.3771v3
+2013-08-23,Quotients and subgroups of Baumslag-Solitar groups,"We determine all generalized Baumslag-Solitar groups (finitely generated
+groups acting on a tree with all stabilizers infinite cyclic) which are
+quotients of a given Baumslag-Solitar group BS(m,n), and (when BS(m,n) is not
+Hopfian) which of them also admit BS(m,n) as a quotient. We determine for which
+values of r,s one may embed BS(r,s) into a given BS(m,n), and we characterize
+finitely generated groups which embed into some BS(n,n).",1308.5122v2
+2013-12-17,Limit theory for the Gilbert graph,"For a given homogeneous Poisson point process in $\mathbb{R}^d$ two points
+are connected by an edge if their distance is bounded by a prescribed distance
+parameter. The behaviour of the resulting random graph, the Gilbert graph or
+random geometric graph, is investigated as the intensity of the Poisson point
+process is increased and the distance parameter goes to zero. The asymptotic
+expectation and covariance structure of a class of length-power functionals are
+computed. Distributional limit theorems are derived that have a Gaussian, a
+stable or a compound Poisson limiting distribution. Finally, concentration
+inequalities are provided using a concentration inequality for the convex
+distance.",1312.4861v2
+2014-03-13,Fibrations of ordered groupoids and the factorization of ordered functors,"We investigate canonical factorizations of ordered functors of ordered
+groupoids through star-surjective functors. Our main construction is a quotient
+ordered groupoid, depending on an ordered version of the notion of normal
+subgroupoid, that results is the factorization of an ordered functor as a
+star-surjective functor followed by a star-injective functor. Any
+star-injective functor possesses a universal factorization through a covering,
+by Ehresmann's Maximum Enlargement Theorem. We also show that any ordered
+functor has a canonical factorization through a functor with the ordered
+homotopy lifting property.",1403.3254v2
+2014-06-10,A thin-film limit in the Landau-Lifshitz-Gilbert equation relevant for the formation of Néel walls,"We consider an asymptotic regime for two-dimensional ferromagnetic films that
+is consistent with the formation of transition layers (N\'eel walls). We first
+establish compactness of S2-valued magnetizations in the energetic regime of
+N\'eel walls and characterize the set of accumulation points. We then prove
+that N\'eel walls are asymptotically the unique energy minimizing
+configurations. We finally study the corresponding dynamical issues, namely the
+compactness properties of the magnetizations under the flow of the
+Landau-Lifshitz-Gilbert equation.",1406.2709v1
+2014-12-11,Gamma factors of pairs and a local converse theorem in families,"We prove a GL(n)xGL(n-1) local converse theorem for l-adic families of smooth
+representations of GL(n,F) where F is a finite extension of Q_p and l is
+different from p. To do so, we also extend the theory of Rankin-Selberg
+integrals, first introduced by Jacquet, Piatetski-Shapiro, and Shalika, to the
+setting of families, continuing previous work of the author.",1412.3500v2
+2015-05-28,A Geometric Interpretation of the Boolean Gilbert-Johnson-Keerthi Algorithm,"The Gilbert-Johnson-Keerthi (GJK) algorithm is an iterative improvement
+technique for finding the minimum distance between two convex objects. It can
+easily be extended to work with concave objects and return the pair of closest
+points. [4] The key operation of GJK is testing whether a Voronoi region of a
+simplex contains the origin or not. In this paper we show that, in the context
+where one is interested only in the Boolean value of whether two convex objects
+intersect, and not in the actual distance between them, the number of test
+cases in GJK can be significantly reduced. This results in a simpler and more
+efficient algorithm that can be used in many computational geometry
+applications.",1505.07873v1
+2016-01-29,Ordered groupoid quotients and congruences on inverse semigroups,"We introduce a preorder on an inverse semigroup $S$ associated to any normal
+inverse subsemigroup $N$, that lies between the natural partial order and
+Green's ${\mathscr J}$-relation. The corresponding equivalence relation
+$\simeq_N$ is not necessarily a congruence on $S$, but the quotient set does
+inherit a natural ordered groupoid structure. We show that this construction
+permits the factorisation of any inverse semigroup homomorphism into a
+composition of a quotient map and a star-injective functor, and that this
+decomposition implies a classification of congruences on $S$. We give an
+application to the congruence and certain normal inverse subsemigroups
+associate to an inverse monoid presentation.",1601.08194v1
+2016-08-16,Closed inverse subsemigroups of graph inverse semigroups,"As part of his study of representations of the polycylic monoids, M.V. Lawson
+described all the closed inverse submonoids of a polycyclic monoid $P_n$ and
+classified them up to conjugacy. We show that Lawson's description can be
+extended to closed inverse subsemigroups of graph inverse semigroups. We then
+apply B. Schein's theory of cosets in inverse semigroups to the closed inverse
+subsemigroups of graph inverse semigroups: we give necessary and sufficient
+conditions for a closed inverse subsemigroup of a graph inverse semigroup to
+have finite index, and determine the value of the index when it is finite.",1608.04538v1
+2016-10-11,Converse theorems and the local Langlands correspondence in families,"We prove a descent criterion for certain families of smooth representations
+of GL_n(F) (F a p-adic field) in terms of the gamma factors of pairs
+constructed in previous work of the second author. We then use this descent
+criterion, together with a theory of gamma factors for families of
+representations of the Weil group W_F (developed previously by both authors),
+to prove a series of conjectures, due to the first author, that give a complete
+description of the integral Bernstein center in terms of Galois theory and the
+local Langlands correspondence. An immediate consequence is the conjectural
+""local Langlands correspondence in families"" of Emerton and Helm.",1610.03277v1
+2016-10-14,An alternative view on dissipation in turbulent flows,"An original experimental setup has been elaborated in order to get a better
+view of turbulent flows in a von Karman geometry. The availability of a very
+fast camera allowed to follow in time the evolution of the flows. A surprising
+finding is that the development of smaller whorls ceases earlier than expected
+and the aspect of the flows remains the same above Reynolds number of a few
+thousand. This fact provides an explanation of the constancy of the reduced
+dissipation in the same range without the need of singularity. Its cause could
+be in relation with the same type of behavior observed in a rotating frame.",1610.05356v2
+2017-03-02,Small Superposition Dimension and Active Set Construction for Multivariate Integration Under Modest Error Demand,"Constructing active sets is a key part of the Multivariate Decomposition
+Method. An algorithm for constructing optimal or quasi-optimal active sets is
+proposed in the paper. By numerical experiments, it is shown that the new
+method can provide sets that are significantly smaller than the sets
+constructed by the already existing method. The experiments also show that the
+superposition dimension could surprisingly be very small, at most 3, when the
+error demand is not smaller than $10^{-3}$ and the weights decay sufficiently
+fast.",1703.00985v1
+2017-03-03,Heat conduction and the nonequilibrium stationary states of stochastic energy exchange processes,"I revisit the exactly solvable Kipnis--Marchioro--Presutti model of heat
+conduction [J. Stat. Phys. 27 65 (1982)] and describe, for one-dimensional
+systems of arbitrary sizes whose ends are in contact with thermal baths at
+different temperatures, a systematic characterization of their non-equilibrium
+stationary states. These arguments avoid resorting to the analysis of a dual
+process and yield a straightforward derivation of Fourier's law, as well as
+higher-order static correlations, such as the covariant matrix. The
+transposition of these results to families of gradient models generalizing the
+KMP model is established and specific cases are examined.",1703.01240v1
+2017-03-04,Algebraic geometry codes with complementary duals exceed the asymptotic Gilbert-Varshamov bound,"It was shown by Massey that linear complementary dual (LCD for short) codes
+are asymptotically good. In 2004, Sendrier proved that LCD codes meet the
+asymptotic Gilbert-Varshamov (GV for short) bound. Until now, the GV bound
+still remains to be the best asymptotical lower bound for LCD codes. In this
+paper, we show that an algebraic geometry code over a finite field of even
+characteristic is equivalent to an LCD code and consequently there exists a
+family of LCD codes that are equivalent to algebraic geometry codes and exceed
+the asymptotical GV bound.",1703.01441v1
+2017-03-17,A finite element approximation for the stochastic Landau--Lifshitz--Gilbert equation with multi-dimensional noise,"We propose an unconditionally convergent linear finite element scheme for the
+stochastic Landau--Lifshitz--Gilbert (LLG) equation with multi-dimensional
+noise. By using the Doss-Sussmann technique, we first transform the stochastic
+LLG equation into a partial differential equation that depends on the solution
+of the auxiliary equation for the diffusion part. The resulting equation has
+solutions absolutely continuous with respect to time. We then propose a
+convergent $\theta$-linear scheme for the numerical solution of the
+reformulated equation. As a consequence, we are able to show the existence of
+weak martingale solutions to the stochastic LLG equation.",1703.05901v1
+2017-04-12,The homology of principally directed ordered groupoids,"We present some homological properties of a relation $\beta$ on ordered
+groupoids that generalises the minimum group congruence for inverse semigroups.
+When $\beta$ is a transitive relation on an ordered groupoid $G$, the quotient
+$G / \beta$ is again an ordered groupoid, and construct a pair of adjoint
+functors between the module categories of $G$ and of $G / \beta$. As a
+consequence, we show that the homology of $G$ is completely determined by that
+of $G / \beta$, generalising a result of Loganathan for inverse semigroups.",1704.03689v1
+2017-06-15,Absence of correlations in the energy exchanges of an exactly solvable model of heat transport with many degrees of freedom,"A process based on the exactly solvable Kipnis--Marchioro--Presutti model of
+heat conduction [J. Stat. Phys. 27 65 (1982)] is described whereby lattice
+cells share their energies among many identical degrees of freedom while, in
+each cell, only two of them are associated with energy exchanges connecting
+neighbouring cells. It is shown that, up to dimensional constants, the heat
+conductivity is half the interaction rate, regardless of the degrees of
+freedom. Moreover, as this number becomes large, correlations between the
+energy variables involved in the exchanges vanish. In this regime, the process
+thus boils down to the time-evolution of the local temperatures which is
+prescribed by the discrete heat equation.",1706.04849v1
+2017-11-29,On the local converse theorem and the descent theorem in families,"We prove an analogue of Jacquet's conjecture on the local converse theorem
+for \ell-adic families of co-Whittaker representations of GL_n(F), where F is a
+finite extension of Q_p and \ell does not equal p. We also prove an analogue of
+Jacquet's conjecture for a descent theorem, which asks for the smallest
+collection of gamma factors determining the subring of definition of an
+\ell-adic family. These two theorems are closely related to the local Langlands
+correspondence in \ell-adic families.",1711.11159v1
+2018-06-23,List Decodability of Symbol-Pair Codes,"We investigate the list decodability of symbol-pair codes in the present
+paper. Firstly, we show that list decodability of every symbol-pair code does
+not exceed the Gilbert-Varshamov bound. On the other hand, we are able to prove
+that with high probability, a random symbol-pair code can be list decoded up to
+the Gilbert-Varshamov bound. Our second result of this paper is to derive the
+Johnson-type bound, i.e., a lower bound on list decoding radius in terms of
+minimum distance. Finally, we present a list decoding algorithm of Reed-Solomon
+codes beyond the Johnson-type bound.",1806.08992v1
+2018-07-05,Volumetric performance capture from minimal camera viewpoints,"We present a convolutional autoencoder that enables high fidelity volumetric
+reconstructions of human performance to be captured from multi-view video
+comprising only a small set of camera views. Our method yields similar
+end-to-end reconstruction error to that of a probabilistic visual hull computed
+using significantly more (double or more) viewpoints. We use a deep prior
+implicitly learned by the autoencoder trained over a dataset of view-ablated
+multi-view video footage of a wide range of subjects and actions. This opens up
+the possibility of high-end volumetric performance capture in on-set and
+prosumer scenarios where time or cost prohibit a high witness camera count.",1807.01950v2
+2018-10-26,Immobilization of convex bodies in $R^n$,"We extend to arbitrary finite $n$ the notion of immobilization of a convex
+body $O$ in $R^n$ by a finite set of points $P$ in the boundary of $O$. Because
+of its importance for this problem, necessary and sufficient conditions are
+found for the immobilization of an $n$-simplex. A fairly complete geometric
+description of these conditions is given: as $n$ increases from $n = 2$, some
+qualitative difference in the nature of the sets $P$ emerges.",1810.11381v1
+2019-01-14,Groupoids and the algebra of rewriting in group presentations,"Presentations of groups by rewriting systems (that is, by monoid
+presentations), have been fruitfully studied by encoding the rewriting system
+in a $2$--complex -- the Squier complex -- whose fundamental groupoid then
+describes the derivation of consequences of the rewrite rules. We describe a
+reduced form of the Squier complex, investigate the structure of its
+fundamental groupoid, and show that key properties of the presentation are
+still encoded in the reduced form.",1901.04348v1
+2019-05-27,Tuning Free Rank-Sparse Bayesian Matrix and Tensor Completion with Global-Local Priors,"Matrix and tensor completion are frameworks for a wide range of problems,
+including collaborative filtering, missing data, and image reconstruction.
+Missing entries are estimated by leveraging an assumption that the matrix or
+tensor is low-rank. Most existing Bayesian techniques encourage rank-sparsity
+by modelling factorized matrices and tensors with Normal-Gamma priors. However,
+the Horseshoe prior and other ""global-local"" formulations provide
+tuning-parameter-free solutions which may better achieve simultaneous
+rank-sparsity and missing-value recovery. We find these global-local priors
+outperform commonly used alternatives in simulations and in a collaborative
+filtering task predicting board game ratings.",1905.11496v1
+2019-06-26,Fairness criteria through the lens of directed acyclic graphical models,"A substantial portion of the literature on fairness in algorithms proposes,
+analyzes, and operationalizes simple formulaic criteria for assessing fairness.
+Two of these criteria, Equalized Odds and Calibration by Group, have gained
+significant attention for their simplicity and intuitive appeal, but also for
+their incompatibility. This chapter provides a perspective on the meaning and
+consequences of these and other fairness criteria using graphical models which
+reveals Equalized Odds and related criteria to be ultimately misleading. An
+assessment of various graphical models suggests that fairness criteria should
+ultimately be case-specific and sensitive to the nature of the information the
+algorithm processes.",1906.11333v1
+2020-01-14,Neural Architecture Search for Deep Image Prior,"We present a neural architecture search (NAS) technique to enhance the
+performance of unsupervised image de-noising, in-painting and super-resolution
+under the recently proposed Deep Image Prior (DIP). We show that evolutionary
+search can automatically optimize the encoder-decoder (E-D) structure and
+meta-parameters of the DIP network, which serves as a content-specific prior to
+regularize these single image restoration tasks. Our binary representation
+encodes the design space for an asymmetric E-D network that typically converges
+to yield a content-specific DIP within 10-20 generations using a population
+size of 500. The optimized architectures consistently improve upon the visual
+quality of classical DIP for a diverse range of photographic and artistic
+content.",2001.04776v1
+2020-07-18,Finslerian convolution metrics and their special classes,"Here, it is introduced a concept of convolution metric in Finslerian
+Geometry. This convolution metric is a kind of function obtained by a given
+mathematical operation between two Finslerian metrics. Some basic properties of
+the Finslerian convolution metrics are studied. Then it is characterized
+Finslerian convolution metrics which are of type Riemannian, Minkowskian as
+well as Randers. Furthermore, some examples of the Finslerian convolutions are
+given.",2007.14803v3
+2020-09-14,What mathematical billiards teach us about statistical physics?,"We survey applications of the theory of hyperbolic (and to a lesser extent
+non hyperbolic) billiards to some fundamental problems of statistical physics
+and their mathematically rigorous derivations in the framework of classical
+Hamiltonian systems.",2009.06284v2
+2020-11-29,Applications of the Backus-Gilbert method to linear and some non linear equations,"We investigate the use of a functional analytical version of the
+Backus-Gilbert Method as a reconstruction strategy to get specific information
+about the solution of linear and slightly non-linear systems with Frech\'et
+derivable operators. Some a priori error estimates are shown and tested for two
+classes of problems: a nonlinear moment problem and a linear elliptic Cauchy
+problem. For this second class of problems a special version of the
+Green-formula is developed in order to analyze the involved adjoint equations.",2011.14407v1
+2021-11-30,Global weak solutions for the Landau-Lifshitz-Gilbert-Vlasov-Maxwell system coupled via emergent electromagnetic fields,"Motivated by recent models of current driven magnetization dynamics, we
+examine the coupling of the Landau-Lifshitz-Gilbert equation and classical
+electron transport governed by the Vlasov-Maxwell system. The interaction is
+based on space-time gyro-coupling in the form of emergent electromagnetic
+fields of quantized helicity that add up to the conventional Maxwell fields. We
+construct global weak solutions of the coupled system in the framework of
+frustrated magnets with competing first and second order gradient interactions
+known to host topological solitons such as magnetic skyrmions and hopfions.",2111.15482v1
+2022-04-02,Introduction to the Artificial Intelligence that can be applied to the Network Automation Journey,"The computer network world is changing and the NetDevOps approach has brought
+the dynamics of applications and systems into the field of communication
+infrastructure. Businesses are changing and businesses are faced with
+difficulties related to the diversity of hardware and software that make up
+those infrastructures. The ""Intent-Based Networking - Concepts and Definitions""
+document describes the different parts of the ecosystem that could be involved
+in NetDevOps. The recognize, generate intent, translate and refine features
+need a new way to implement algorithms. This is where artificial intelligence
+comes in.",2204.00800v1
+2022-05-24,Theory of the Energy Variance in a Quantum Bit,"We define a new quantum Hermitian operator (namely, the energy variance
+operator) which is simply duplicated from the statistical definition of energy
+variance in classical physics. Its expectation value yields the standard
+deviation of the energy about the mean value of this latter. We show by use of
+an exact Hamiltonian description that this standard deviation is due to the
+high-frequeny energy oscillations which are usually discarded in the rotating
+wave aproximation. We check the present theory by recovering the duration of an
+abrupt quantum jump that has been described in a recent experiment.",2205.12763v1
+2022-07-11,Quasilinear rough evolution equations,"We investigate the abstract Cauchy problem for a quasilinear parabolic
+equation in a Banach space of the form \( du_t -L_t(u_t)u_t dt = N_t(u_t)dt +
+F(u_t)\cdot d\mathbf X_t \), where \( \mathbf X\) is a \( \gamma\)-H\""older
+rough path for \( \gamma\in(1/3,1/2)\). We explore the mild formulation that
+combines functional analysis techniques and controlled rough paths theory which
+entail the local well-posedness of such equations. We apply our results to the
+stochastic Landau-Lifshitz-Gilbert and Shigesada-Kawasaki-Teramoto equation. In
+this framework we obtain a random dynamical system associated to the
+Landau-Lifshitz-Gilbert equation.",2207.04787v1
+2022-08-01,A Pansiot-type subword complexity theorem for automorphisms of free groups,"Inspired by Pansiot's work on substitutions, we prove a similar theorem for
+automorphisms of a free group F of finite rank: if a right-infinite word
+represents an attracting fixed point of an automorphism of F, the subword
+complexity of X is equivalent to n, n log log n, n log n, or n^2. The proof
+uses combinatorial arguments analogue to Pansiot's as well as train tracks. We
+also define the recurrence complexity of X, and we apply it to laminations. In
+particular, we show that attracting laminations have complexity equivalent to
+n, n log log n, n log n, or n^2 (to n if the automorphism is fully
+irreducible).",2208.00676v1
+2022-08-13,May the force be with you,"Modern methods in dimensionality reduction are dominated by nonlinear
+attraction-repulsion force-based methods (this includes t-SNE, UMAP,
+ForceAtlas2, LargeVis, and many more). The purpose of this paper is to
+demonstrate that all such methods, by design, come with an additional feature
+that is being automatically computed along the way, namely the vector field
+associated with these forces. We show how this vector field gives additional
+high-quality information and propose a general refinement strategy based on
+ideas from Morse theory. The efficiency of these ideas is illustrated
+specifically using t-SNE on synthetic and real-life data sets.",2208.06676v1
+2022-10-26,Linearized frequency domain Landau-Lifshitz-Gilbert equation formulation,"We present a general finite element linearized Landau-Lifshitz-Gilbert
+equation (LLGE) solver for magnetic systems under weak time-harmonic excitation
+field. The linearized LLGE is obtained by assuming a small deviation around the
+equilibrium state of the magnetic system. Inserting such expansion into LLGE
+and keeping only first order terms gives the linearized LLGE, which gives a
+frequency domain solution for the complex magnetization amplitudes under an
+external time-harmonic applied field of a given frequency. We solve the linear
+system with an iterative solver using generalized minimal residual method. We
+construct a preconditioner matrix to effectively solve the linear system. The
+validity, effectiveness, speed, and scalability of the linear solver are
+demonstrated via numerical examples.",2210.14525v1
+2022-11-10,Secure Aggregation Is Not All You Need: Mitigating Privacy Attacks with Noise Tolerance in Federated Learning,"Federated learning is a collaborative method that aims to preserve data
+privacy while creating AI models. Current approaches to federated learning tend
+to rely heavily on secure aggregation protocols to preserve data privacy.
+However, to some degree, such protocols assume that the entity orchestrating
+the federated learning process (i.e., the server) is not fully malicious or
+dishonest. We investigate vulnerabilities to secure aggregation that could
+arise if the server is fully malicious and attempts to obtain access to
+private, potentially sensitive data. Furthermore, we provide a method to
+further defend against such a malicious server, and demonstrate effectiveness
+against known attacks that reconstruct data in a federated learning setting.",2211.06324v1
+2022-12-22,Theory and construction of Quasi-Monte Carlo rules for option pricing and density estimation,"In this paper we propose and analyse a method for estimating three quantities
+related to an Asian option: the fair price, the cumulative distribution
+function, and the probability density. The method involves preintegration with
+respect to one well chosen integration variable to obtain a smooth function of
+the remaining variables, followed by the application of a tailored lattice
+Quasi-Monte Carlo rule to integrate over the remaining variables.",2212.11493v2
+2022-12-30,Asymptotic stability of 2-domain walls for the Landau-Lifshitz-Gilbert equation in a nanowire with Dzyaloshinskii-Moriya interaction,"We consider a ferromagnetic nanowire, with an energy functional $E$ with
+easy-axis in the direction $e_1$, and which takes into account the
+Dzyaloshinskii-Moriya interaction. We consider configurations of the
+magnetization which are perturbations of two well separated domain wall, and
+study their evolution under the Landau-Lifshitz-Gilbert flow associated to E.
+Our main result is that, if the two walls have opposite speed, these
+configurations are asymptotically stable, up to gauges intrinsic to the
+invariances of the energy $E$. Our analysis builds on the framework developed
+in [4], taking advantage that it is amenable to space localisation.",2212.14589v1
+2023-01-12,Time Domain Verification of Differential Transmission Line Modeling Methods,"The advantages and limitations of time-domain pseudo-random binary sequence
+(PRBS) excitation methods for system identification of individual modes within
+a multi-conductor transmission system are discussed. We develop the
+modifications necessary to standard frequency-domain transmission-line models
+to match time-domain experimental data from several types of transmission
+systems. We show a variety of experimental results showing very good to
+excellent agreement with our model's predictions, up to approximately 10 GHz.",2301.05281v1
+2023-01-17,Power Supply Compensation for Capacitive Loads,"As ASIC supply voltages approach one volt, the source-impedance goals for
+power distribution networks are driven ever lower as well. One approach to
+achieving these goals is to add decoupling capacitors of various values until
+the desired impedance profile is obtained. An unintended consequence of this
+approach can be reduced power supply stability and even oscillation. In this
+paper, we present a case study of a system design which encountered these
+problems and we describe how these problems were resolved. Time-domain and
+frequency-domain analysis techniques are discussed and measured data is
+presented.",2301.09580v1
+2023-01-17,Applications of Optimization Routines in Signal Integrity Analysis,"Signal integrity analysis often involves the development of design guidelines
+through manual manipulation of circuit parameters and judicious interpretation
+of results. Such an approach can result in significant effort and sub-optimal
+conclusions. Optimization routines have been well proven to aid analysis across
+a variety of common tasks. In addition, there are several non-traditional
+applications where optimization can be useful. This paper begins by describing
+the basics of optimization followed by two specific case studies where
+non-traditional optimization provides significant improvements in both analysis
+efficiency and channel performance.",2301.10157v1
+2023-01-17,High Speed Parallel Signal Crosstalk Cancellation Concept,"High performance computing (HPC) systems make extensive use of high speed
+electrical interconnects, in routing signals among processing elements, or
+between processing elements and memory. Increasing bandwidth demands result in
+high density, parallel I/O exposed to crosstalk due to tightly coupled
+transmission lines. The crosstalk cancellation signaling concept discussed in
+this paper utilizes the known, predictable theory of coupled transmission lines
+to cancel crosstalk from neighboring traces with carefully chosen resistive
+cross-terminations between them. Through simulation and analysis of practical
+bus architectures, we explore the merits of crosstalk cancellation which could
+be used in dense interconnect HPC (or other) applications.",2301.10170v1
+2023-04-05,Elimination and Factorization,"If a matrix $A$ has rank $r$, then its row echelon form (from elimination)
+contains the identity matrix in its first $r$ independent columns. How do we
+\emph{interpret the matrix} $F$ that appears in the remaining columns of that
+echelon form\,? $F$ multiplies those first $r$ independent columns of $A$ to
+give its $n-r$ dependent columns. Then $F$ reveals bases for the row space and
+the nullspace of the original matrix $A$. And $F$ is the key to the column-row
+factorization $\boldsymbol{A}=\boldsymbol{CR}$.",2304.02659v1
+2023-04-25,Jet: Multilevel Graph Partitioning on Graphics Processing Units,"The multilevel heuristic is the dominant strategy for high-quality sequential
+and parallel graph partitioning. Partition refinement is a key step of
+multilevel graph partitioning. In this work, we present Jet, a new parallel
+algorithm for partition refinement specifically designed for Graphics
+Processing Units (GPUs). We combine Jet with GPU-aware coarsening to develop a
+$k$-way graph partitioner, the Jet partitioner. The new partitioner achieves
+superior quality compared to state-of-the-art shared memory partitioners on a
+large collection of test graphs.",2304.13194v2
+2023-05-16,QHDL: a Low-Level Circuit Description Language for Quantum Computing,"This paper proposes a descriptive language called QHDL, akin to VHDL, to
+program gate-based quantum computing systems. Unlike other popular quantum
+programming languages, QHDL targets low-level quantum computing programming and
+aims to provide a common framework for programming FPGAs and gate-based quantum
+computing systems. The paper presents an initial implementation and design
+principles of the QHDL framework, including a compiler and quantum computer
+simulator. We discuss the challenges of low-level integration of streaming
+models and quantum computing for programming FPGAs and gate-based quantum
+computing systems.",2305.09419v1
+2023-05-21,An Alternative Derivation of the Landau-Lifshitz-Gilbert Equation for Saturated Ferromagnets,"The Landau-Lifshitz-Gilbert equation for rigid and saturated ferromagnets is
+derived using a two-continuum model constructed by H.F. Tiersten for elastic
+and saturated ferromagnets. The relevant basic laws of physics are applied
+systematically to the two continua or their combination. The exchange
+interaction is introduced into the model through surface distributed magnetic
+couples. This leads to a continuum theory with magnetization gradients in the
+stored energy density. The saturation condition of the magnetization functions
+as constraints on the energy density and has implications in the constitutive
+relations.",2305.18232v1
+2023-06-25,Gilbert's conjecture and A new way to octonionic analytic functions from the clifford analysis,"In this article we will give a affirmative answer to Gilbert's conjecture on
+Hardy spaces of Clifford analytic functions in upper half-space of
+$\mathbb{R}^8$. It depends on a explicit construction of Spinor space
+$\mathcal{R}_8$ and Clifford algebra $Cl_8$ by octonion algbra. What's more ,
+it gives us an associative way to octonionic analytic function theory. And the
+similar question has been discussed in Octonionic Hardy space in upper-half
+space, some classical results about octonionic analytic functions have been
+reformulated, too.",2306.14164v1
+2023-06-28,Stochastic Landau-Lifshitz-Gilbert equations for frustrated magnets under fluctuating currents,"We examine a stochastic Landau-Lifshitz-Gilbert equation for a frustrated
+ferromagnet with competing first and second order exchange interactions exposed
+to deterministic and random spin transfer torques in form of transport noise.
+We prove the existence and pathwise uniqueness of weak martingale solutions in
+the energy space. The result ensures the persistence of topological patterns,
+occurring in such magnetic systems, under the influence of a fluctuating spin
+current.",2306.15843v1
+2023-07-28,"MDS, Hermitian Almost MDS, and Gilbert-Varshamov Quantum Codes from Generalized Monomial-Cartesian Codes","We construct new stabilizer quantum error-correcting codes from generalized
+monomial-Cartesian codes. Our construction uses an explicitly defined twist
+vector, and we present formulas for the minimum distance and dimension.
+Generalized monomial-Cartesian codes arise from polynomials in $m$ variables.
+When $m=1$ our codes are MDS, and when $m=2$ and our lower bound for the
+minimum distance is $3$ the codes are at least Hermitian Almost MDS. For an
+infinite family of parameters when $m=2$ we prove that our codes beat the
+Gilbert-Varshamov bound. We also present many examples of our codes that are
+better than any known code in the literature.",2307.15488v1
+2023-09-06,Optimal Control of the 2D Landau-Lifshitz-Gilbert Equation with Control Energy in Effective Magnetic Field,"The optimal control of magnetization dynamics in a ferromagnetic sample at a
+microscopic scale is studied. The dynamics of this model is governed by the
+Landau-Lifshitz-Gilbert equation on a two-dimensional bounded domain with the
+external magnetic field (the control) applied through the effective field. We
+prove the global existence and uniqueness of a regular solution in $\mathbb
+S^2$ under a smallness condition on control and initial data. We establish the
+existence of optimal control and derive a first-order necessary optimality
+condition using the Fr\'echet derivative of the control-to-state operator and
+adjoint problem approach.",2309.02786v1
+2023-09-22,Relaxed optimal control for the stochastic Landau-Lifshitz-Gilbert equation,"We consider the stochastic Landau-Lifshitz-Gilbert equation, perturbed by a
+real-valued Wiener process. We add an external control to the effective field
+as an attempt to drive the magnetization to a desired state and also to control
+thermal fluctuations. We use the theory of Young measures to relax the given
+control problem along with the associated cost. We consider a control operator
+that can depend (possibly non-linearly) on both the control and the associated
+solution. Moreover, we consider a fairly general associated cost functional
+without any special convexity assumption. We use certain compactness arguments,
+along with the Jakubowski version of the Skorohod Theorem to show that the
+relaxed problem admits an optimal control.",2309.12556v1
+2024-01-14,Multilevel Metamodels: A Novel Approach to Enhance Efficiency and Generalizability in Monte Carlo Simulation Studies,"Metamodels, or the regression analysis of Monte Carlo simulation (MCS)
+results, provide a powerful tool to summarize MCS findings. However, an as of
+yet unexplored approach is the use of multilevel metamodels (MLMM) that better
+account for the dependent data structure of MCS results that arises from
+fitting multiple models to the same simulated data set. In this study, we
+articulate the theoretical rationale for the MLMM and illustrate how it can
+dramatically improve efficiency over the traditional regression approach,
+better account for complex MCS designs, and provide new insights into the
+generalizability of MCS findings.",2401.07294v2
+2024-02-29,Evaluating the Gilbert-Varshamov Bound for Constrained Systems,"We revisit the well-known Gilbert-Varshamov (GV) bound for constrained
+systems. In 1991, Kolesnik and Krachkovsky showed that GV bound can be
+determined via the solution of some optimization problem. Later, Marcus and
+Roth (1992) modified the optimization problem and improved the GV bound in many
+instances. In this work, we provide explicit numerical procedures to solve
+these two optimization problems and hence, compute the bounds. We then show the
+procedures can be further simplified when we plot the respective curves. In the
+case where the graph presentation comprise a single state, we provide explicit
+formulas for both bounds.",2402.18869v1
+2003-08-25,Detection of molecular hydrogen at z=1.15 toward HE 0515-4414,"A new molecular hydrogen cloud is found in the sub-damped Ly-alpha absorber
+[log N(HI)=19.88+/-0.05] at the redshift z=1.15 toward the bright quasar
+HE0515-4414 (zem = 1.71). More than 30 absorption features in the Lyman band
+system of H2 are identified in the UV spectrum of this quasar obtained with the
+Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope.
+The H2-bearing cloud shows a total H2 column density N(H2)=(8.7^{+8.7}_-{4.0})
+10^16 cm^-2, and a fractional molecular abundance f(H2)=(2.3^{+2.3}_{-1.1})
+10^-3 derived from the H2 lines arising from the J=0-5 rotational levels of the
+ground electronic vibrational state. The estimated rate of photodissociation at
+the cloud edge I_0<=1.8 10^{-8} s^-1 is much higher than the mean Galactic disk
+value, I_MW~=5.5 10^{-11} s^-1. This may indicate an enhanced star-formation
+activity in the z=1.15 system as compared with molecular clouds at z~=3 where
+I~=I_MW. We also find a tentative evidence that the formation rate coefficient
+of H2 upon grain surfaces at z=1.15 is a factor of 10 larger than a canonical
+Milky Way value, R_MW~=3 10^-17 cm^3 s^-1. The relative dust-to-gas ratio
+estimated from the [Cr/Zn] ratio is equal to k=0.89+/-0.19 (in units of the
+mean Galactic disk value), which is in good agreement with a high molecular
+fraction in this system. The estimated line-of-sight size of L~=0.25 pc may
+imply that the H2 is confined within small and dense filaments embedded in a
+more rarefied gas giving rise to the z=1.15 sub-damped Ly-alpha absorber.",0308432v1
+2004-10-04,Dissipative dynamics of topological defects in frustrated Heisenberg spin systems,"We study the dynamics of topological defects of a frustrated spin system
+displaying spiral order. As a starting point we consider the SO(3) nonlinear
+sigma model to describe long-wavelength fluctuations around the noncollinear
+spiral state. Besides the usual spin-wave magnetic excitations, the model
+allows for topologically non-trivial static solutions of the equations of
+motion, associated with the change of chirality (clockwise or counterclockwise)
+of the spiral. We consider two types of these topological defects, single
+vortices and vortex-antivortex pairs, and quantize the corresponding solutions
+by generalizing the semiclassical approach to a non-Abelian field theory. The
+use of the collective coordinates allows us to represent the defect as a
+particle coupled to a bath of harmonic oscillators, which can be integrated out
+employing the Feynman-Vernon path-integral formalism. The resulting effective
+action for the defect indicates that its motion is damped due to the scattering
+by the magnons. We derive a general expression for the damping coefficient of
+the defect, and evaluate its temperature dependence in both cases, for a single
+vortex and for a vortex-antivortex pair. Finally, we consider an application of
+the model for cuprates, where a spiral state has been argued to be realized in
+the spin-glass regime. By assuming that the defect motion contributes to the
+dissipative dynamics of the charges, we can compare our results with the
+measured inverse mobility in a wide range of temperature. The relatively good
+agreement between our calculations and the experiments confirms the possible
+relevance of an incommensurate spiral order for lightly doped cuprates.",0410082v3
+2010-09-14,Modeling laser wakefield accelerators in a Lorentz boosted frame,"Modeling of laser-plasma wakefield accelerators in an optimal frame of
+reference \cite{VayPRL07} is shown to produce orders of magnitude speed-up of
+calculations from first principles. Obtaining these speedups requires
+mitigation of a high-frequency instability that otherwise limits effectiveness
+in addition to solutions for handling data input and output in a
+relativistically boosted frame of reference. The observed high-frequency
+instability is mitigated using methods including an electromagnetic solver with
+tunable coefficients, its extension to accomodate Perfectly Matched Layers and
+Friedman's damping algorithms, as well as an efficient large bandwidth digital
+filter. It is shown that choosing the frame of the wake as the frame of
+reference allows for higher levels of filtering and damping than is possible in
+other frames for the same accuracy. Detailed testing also revealed
+serendipitously the existence of a singular time step at which the instability
+level is minimized, independently of numerical dispersion, thus indicating that
+the observed instability may not be due primarily to Numerical Cerenkov as has
+been conjectured. The techniques developed for Cerenkov mitigation prove
+nonetheless to be very efficient at controlling the instability. Using these
+techniques, agreement at the percentage level is demonstrated between
+simulations using different frames of reference, with speedups reaching two
+orders of magnitude for a 0.1 GeV class stages. The method then allows direct
+and efficient full-scale modeling of deeply depleted laser-plasma stages of 10
+GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to
+very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for
+the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.",1009.2727v2
+2013-03-07,The coupling between internal waves and shear-induced turbulence in stellar radiation zones: the critical layer,"Internal gravity waves (hereafter IGWs) are known as one of the candidates
+for explaining the angular velocity profile in the Sun and in solar-type
+main-sequence and evolved stars, due to their role in the transport of angular
+momentum. Our bringing concerns critical layers, a process poorly explored in
+stellar physics, defined as the location where the local relative frequency of
+a given wave to the rotational frequency of the fluid tends to zero (i.e that
+corresponds to co-rotation resonances). IGW propagate through stably-stratified
+radiative regions, where they extract or deposit angular momentum through two
+processes: radiative and viscous dampings and critical layers. Our goal is to
+obtain a complete picture of the effects of this latters. First, we expose a
+mathematical resolution of the equation of propagation for IGWs in adiabatic
+and non-adiabatic cases near critical layers. Then, the use of a dynamical
+stellar evolution code, which treats the secular transport of angular momentum,
+allows us to apply these results to the case of a solar-like star.The analysis
+reveals two cases depending on the value of the Richardson number at critical
+layers: a stable one, where IGWs are attenuated as they pass through a critical
+level, and an unstable turbulent case where they can be reflected/transmitted
+by the critical level with a coefficient larger than one. Such
+over-reflection/transmission can have strong implications on our vision of
+angular momentum transport in stellar interiors. This paper highlights the
+existence of two regimes defining the interaction between an IGW and a critical
+layer. An application exposes the effect of the first regime, showing a
+strengthening of the damping of the wave. Moreover, this work opens new ways
+concerning the coupling between IGWs and shear instabilities in stellar
+interiors.",1303.1715v1
+2014-05-01,Energy Loss of Solar $p$ Modes due to the excitation of Magnetic Sausage Tube Waves: Importance of Coupling the Upper Atmosphere,"We consider damping and absorption of solar $p$ modes due to their energy
+loss to magnetic tube waves that can freely carry energy out of the acoustic
+cavity. The coupling of $p$ modes and sausage tube waves is studied in a model
+atmosphere composed of a polytropic interior above which lies an isothermal
+upper atmosphere. The sausage tube waves, excited by $p$ modes, propagate along
+a magnetic fibril which is assumed to be a vertically aligned, stratified, thin
+magnetic flux-tube. The deficit of $p$-mode energy is quantified through the
+damping rate, $\Gamma$ and absorption coefficient, $\alpha$. The variation of
+$\Gamma$ and $\alpha$ as a function of frequency and the tube's plasma
+properties is studied in detail. Previous similar studies have considered only
+a subphotospheric layer, modelled as a polytrope that has been truncated at the
+photosphere (Bogdan et al. (1996), Hindman & Jain 2008, Gascoyne et al.
+(2011)). Such studies have found that the resulting energy loss by the $p$
+modes is very sensitive to the upper boundary condition, which because of the
+lack of a upper atmosphere have been imposed in a somewhat ad hoc manner. The
+model presented here avoids such problems by using an isothermal layer to model
+the overlying atmosphere (chromosphere), and consequently, allows us to analyse
+the propagation of $p$-mode driven sausage waves above the photosphere. In this
+paper we restrict our attention to frequencies below the acoustic cut-off
+frequency. We demonstrate the importance of coupling all waves (acoustic,
+magnetic) in the subsurface solar atmosphere with the overlying atmosphere in
+order to accurately model the interaction of solar $f$ and $p$ modes with
+sausage tube waves.",1405.0130v2
+2015-09-01,Excitation of surface and volume plasmons in metal nanocluster by fast electrons,"Surface and volume plasmons excited in a metal cluster by moving electron and
+corresponding inelastic scattering spectra are studied based on the
+hydrodynamic approach. Along with the bulk losses traditionally taken into
+account, the surface and radiative ones are also considered as the physical
+mechanisms responsible for the plasmon damping. The second and third mechanisms
+are found to be essential for the surface plasmons and depend very differently
+on the multipole mode order. The differential equations are obtained which
+describe the temporal evolution of every particular mode as that one of a
+linear oscillator excited by the given external force, and the electron energy
+loss spectra are calculated. The changes in spectrum shape with the impact
+parameter and with the electron passage time are analyzed and found to be in
+good enough agreement with the data of scanning transmission electron
+microscopy (STEM) experiments. It is shown that, in the general case, a
+pronounced contribution to the formation of the loss spectrum is given by the
+both surface and volume plasmons with low and high multipole indices. In
+particular, at long electron passage time, the integral loss spectrum which is
+calculated for the free-electron cluster model contains two main peaks: a broad
+peak from merging of many high-order multipole resonances of the surface
+plasmons and a narrower peak of nearly the same height from merged volume
+plasmons excited by the electrons that travel through the central region of the
+cluster. Comparatively complex dependences of the calculated excitation
+coefficients and damping constants of various plasmons on the order of the
+excited multipole result in wide diversity of possible types of the loss
+spectrum even for the same cluster material and should be taken into account in
+interpretation of corresponding electron energy loss spectroscopy (EELS)
+experiments.",1509.00405v2
+2016-01-29,New class of quantum error-correcting codes for a bosonic mode,"We construct a new class of quantum error-correcting codes for a bosonic mode
+which are advantageous for applications in quantum memories, communication, and
+scalable computation. These 'binomial quantum codes' are formed from a finite
+superposition of Fock states weighted with binomial coefficients. The binomial
+codes can exactly correct errors that are polynomial up to a specific degree in
+bosonic creation and annihilation operators, including amplitude damping and
+displacement noise as well as boson addition and dephasing errors. For
+realistic continuous-time dissipative evolution, the codes can perform
+approximate quantum error correction to any given order in the timestep between
+error detection measurements. We present an explicit approximate quantum error
+recovery operation based on projective measurements and unitary operations. The
+binomial codes are tailored for detecting boson loss and gain errors by means
+of measurements of the generalized number parity. We discuss optimization of
+the binomial codes and demonstrate that by relaxing the parity structure, codes
+with even lower unrecoverable error rates can be achieved. The binomial codes
+are related to existing two-mode bosonic codes but offer the advantage of
+requiring only a single bosonic mode to correct amplitude damping as well as
+the ability to correct other errors. Our codes are similar in spirit to 'cat
+codes' based on superpositions of the coherent states, but offer several
+advantages such as smaller mean number, exact rather than approximate
+orthonormality of the code words, and an explicit unitary operation for
+repumping energy into the bosonic mode. The binomial quantum codes are
+realizable with current superconducting circuit technology and they should
+prove useful in other quantum technologies, including bosonic quantum memories,
+photonic quantum communication, and optical-to-microwave up- and
+down-conversion.",1602.00008v3
+2016-05-31,Constraint on a cosmological variation in the proton-to-electron mass ratio from electronic CO absorption,"Carbon monoxide (CO) absorption in the sub-damped Lyman-$\alpha$ absorber at
+redshift $z_{abs} \simeq 2.69$, toward the background quasar SDSS
+J123714.60+064759.5 (J1237+0647), was investigated for the first time in order
+to search for a possible variation of the proton-to-electron mass ratio, $\mu$,
+over a cosmological time-scale. The observations were performed with the Very
+Large Telescope/Ultraviolet and Visual Echelle Spectrograph with a
+signal-to-noise ratio of 40 per 2.5 kms$^{-1}$ per pixel at $\sim 5000$ \AA.
+Thirteen CO vibrational bands in this absorber are detected: the A$^{1}\Pi$ -
+X$^{1}\Sigma^{+}$ ($\nu'$,0) for $\nu' = 0 - 8$, B$^{1}\Sigma^{+}$ -
+X$^{1}\Sigma^{+}$ (0,0), C$^{1}\Sigma^{+}$ - X$^{1}\Sigma^{+}$ (0,0), and
+E$^{1}\Pi$ - X$^{1}\Sigma^{+}$ (0,0) singlet-singlet bands and the
+d$^{3}\Delta$ - X$^{1}\Sigma^{+}$ (5,0) singlet-triplet band. An updated
+database including the most precise molecular inputs needed for a
+$\mu$-variation analysis is presented for rotational levels $J = 0 - 5$,
+consisting of transition wavelengths, oscillator strengths, natural lifetime
+damping parameters, and sensitivity coefficients to a variation of the
+proton-to-electron mass ratio. A comprehensive fitting method was used to fit
+all the CO bands at once and an independent constraint of $\Delta\mu/\mu = (0.7
+\pm 1.6_{stat} \pm 0.5_{syst}) \times 10^{-5}$ was derived from CO only. A
+combined analysis using both molecular hydrogen and CO in the same J1237+0647
+absorber returned a final constraint on the relative variation of
+$\Delta\mu/\mu = (-5.6 \pm 5.6_{stat} \pm 3.1_{syst}) \times 10^{-6}$, which is
+consistent with no variation over a look-back time of $\sim 11.4$ Gyrs.",1605.09742v1
+2017-11-01,Entanglement entropy of a three-spin interacting spin chain with a time-reversal breaking impurity at one boundary,"We investigate the effect of a time-reversal breaking impurity term on both
+the equilibrium and non-equilibrium critical properties of entanglement entropy
+(EE) in a three-spin interacting transverse Ising model which can be mapped to
+a one-dimensional p-wave superconductor with next-nearest-neighbor hopping. Due
+to the presence of next-nearest-neighbor hopping, a new topological phase with
+two zero-energy Majorana modes at each end of an open chain appears in the
+phase diagram. We show that the derivative of EE with respect to one of the
+parameters of the Hamiltonian can detect the quantum phase transitions by
+exhibiting cusp like structure at those points; impurity strength ($\la_d$) can
+substantially modify the peak/dip height associated with the cusp. Importantly,
+we find that the logarithmic scaling of the EE with block size remains
+unaffected by the application of the impurity term, although, the coefficient
+(i.e., central charge) varies logarithmically with the impurity strength for a
+lower range of $\la_d$ and eventually saturates with an exponential damping
+factor ($\sim \exp(-\la_d)$) for the phase boundaries shared with the phase
+containing two Majorana edge modes. On the other hand, it receives a linear
+correction in term of $\la_d$ for an another phase boundary. Finally, we focus
+to study the effect of the impurity in the time evolution of the EE for the
+critical quenching case where impurity term is applied only to the final
+Hamiltonian. Interestingly, it has been shown that for all the phase boundaries
+in contrary to the equilibrium case, the saturation value of the EE increases
+logarithmically with the strength of impurity in a certain region of $\la_d$
+and finally, for higher values of $\la_d$, it increases very slowly which is
+dictated by an exponential damping factor.",1711.01164v2
+2018-01-23,Predicting Quasar Continua Near Lyman-$α$ with Principal Component Analysis,"Measuring the proximity effect and the damping wing of intergalactic neutral
+hydrogen in quasar spectra during the epoch of reionization requires an
+estimate of the intrinsic continuum at rest-frame wavelengths $\lambda_{\rm
+rest}\sim1200$-$1260$ {\AA}. In contrast to previous works which used composite
+spectra with matched spectral properties or explored correlations between
+parameters of broad emission lines, we opted for a non-parametric predictive
+approach based on principal component analysis (PCA) to predict the intrinsic
+spectrum from the spectral properties at redder (i.e. unabsorbed) wavelengths.
+We decomposed a sample of $12764$ spectra of $z\sim2$-$2.5$ quasars from
+SDSS/BOSS into 10 red-side ($1280$ {\AA} $<\lambda_{\rm rest}<2900$ {\AA}) and
+6 blue-side ($1180$ {\AA} $<\lambda_{\rm rest}<1280$ {\AA}) PCA basis spectra,
+and constructed a projection matrix to predict the blue-side coefficients from
+a fit to the red-side spectrum. We found that our method predicts the blue-side
+continuum with $\sim6$-$12\%$ precision and $\lesssim1\%$ bias by testing on
+the full training set sample. We then computed predictions for the blue-side
+continua of the two quasars currently known at $z>7$: ULAS J1120+0641
+($z=7.09$) and ULAS J1342+0928 ($z=7.54$). Both of these quasars are known to
+exhibit extreme emission line properties, so we individually calibrated the
+precision of the continuum predictions from similar quasars in the training
+set. We find that both $z>7$ quasars, and in particular ULAS J1342+0928, show
+signs of damping wing-like absorption at wavelengths redward of Ly$\alpha$.",1801.07679v1
+2018-05-23,Quantifying the validity and breakdown of the overdamped approximation in stochastic thermodynamics: Theory and experiment,"Stochastic thermodynamics provides an important framework to explore small
+physical systems where thermal fluctuations are inevitable. In the studies of
+stochastic thermodynamics, some thermodynamic quantities, such as the
+trajectory work, associated with the complete Langevin equation (the Kramers
+equation) are often assumed to converge to those associated with the overdamped
+Langevin equation (the Smoluchowski equation) in the overdamped limit under the
+overdamped approximation. Nevertheless, a rigorous mathematical proof of the
+convergence of the work distributions to our knowledge has not been reported so
+far. Here we study the convergence of the work distributions explicitly. In the
+overdamped limit, we rigorously prove the convergence of the extended
+Fokker-Planck equations including work using a multiple timescale expansion
+approach. By taking the linearly dragged harmonic oscillator as an exactly
+solvable example, we analytically calculate the work distribution associated
+with the Kramers equation, and verify its convergence to that associated with
+the Smoluchowski equation in the overdamped limit. We quantify the accuracy of
+the overdamped approximation as a function of the damping coefficient. In
+addition, we experimentally demonstrate that the data of the work distribution
+of a levitated silica nanosphere agrees with the overdamped approximation in
+the overdamped limit, but deviates from the overdamped approximation in the
+low-damping case. Our work fills a gap between the stochastic thermodynamics
+based on the complete Langevin equation (the Kramers equation) and the
+overdamped Langevin equation (the Smoluchowski equation), and deepens our
+understanding of the overdamped approximation in stochastic thermodynamics.",1805.09080v3
+2018-09-05,Experiments on wave propagation in grease ice: combined wave gauges and PIV measurements,"Water wave attenuation by grease ice is a key mechanism for the polar
+regions, as waves in ice influence many phenomena such as ice drift, ice
+breaking, and ice formation. However, the models presented so far in the
+literature are limited in a number of regards, and more insights are required
+from either laboratory experiments or fieldwork for these models to be
+validated and improved. Unfortunately, performing detailed measurements of wave
+propagation in grease ice, either on the field or in the laboratory, is
+challenging. As a consequence, laboratory data are relatively scarce, and often
+consist of only a couple of wave elevation measurements along the length of the
+wave tank. We present combined measurements of wave elevation using an array of
+ultrasonic probes, and water kinematics using Particle Image Velocimetry (PIV),
+in a small-scale wave tank experiment. Experiments are performed over a wider
+frequency range than what has been previously investigated. The wave elevation
+measurements are used to compute the wave number and exponential damping
+coefficient. By contrast with a previous study in grease ice, we find that the
+wave number is consistent with the mass loading model, i.e. it increases
+compared with the open water case. Wave attenuation is compared with a series
+of one-layer models, and we show that they satisfactorily describe the viscous
+damping that is taking place. PIV data are also consistent with exponential
+wave amplitude attenuation, and a POD analysis reveals the existence of mean
+flows under the ice that are a consequence of the displacement and packing of
+the ice induced by the gradient in the wave-induced stress. Finally, we show
+that the dynamics of grease ice can generate eddy structures that inject eddy
+viscosity in the water under the grease ice, which would lead to enhanced
+mixing and participating in energy dissipation.",1809.01476v2
+2022-02-08,"Evolution of energy, momentum, and spin parameter in dark matter flow and integral constants of motion","N-body equations of motion in comoving system and expanding background are
+reformulated in a transformed system with static background and fixed damping.
+The energy and momentum evolution in dark matter flow are rigorously formulated
+for both systems. The energy evolution in transformed system has a simple form
+that is identical to the damped harmonic oscillator. The cosmic energy equation
+can be easily derived in both systems. For entire N-body system, 1) combined
+with the two-body collapse model (TBCM), kinetic and potential energy increase
+linearly with time $t$ such that $K_p=\varepsilon_ut$ and
+$P_y=-7\varepsilon_ut/5$, where $\varepsilon_u$ is a constant rate of energy
+cascade; 2) an effective gravitational potential exponent $n_e=-10/7\ne-1$
+($n_e=-1.38$ from simulation) can be identified due to surface energy of fast
+growing halos; 3) the radial momentum $G\propto a^{3/2}$ and angular momentum
+$H\propto a^{5/2}$, where $a$ is the scale factor. On halo scale, 1) halo
+kinetic and potential energy can be modelled by two dimensionless constants
+$\alpha_s^*$ and $\beta_s^*$. Both constants are independent of time and halo
+mass; 2) both halo radial and angular momentum $\propto a^{3/2}$ and can be
+modeled by two mass-dependent coefficients $\tau_s^*$ and $\eta_s^*$; 3) halo
+spin parameter is determined by $\alpha_s^*$ and $\eta_s^*$ and decreases with
+halo mass with derived values of 0.09 and 0.031 for small and large halos.
+Finally, the radial and angular momentum are closely related to the integral
+constants of motion $I_m$, i.e. the integral of velocity correlation or the
+$m$th derivative of energy spectrum at long wavelength limit. On large scale,
+angular momentum is negligible, $I_2$=0 reflects the conservation of linear
+momentum, while $I_4$ reflects the fluctuation of radial momentum $G$. On halo
+scale, $I_4$ is determined by both momentum that are comparable with each
+other.",2202.04054v2
+2022-09-10,Self-Consistent Computation of Spin Torques and Magneto-Resistance in Tunnel Junctions and Magnetic Read-Heads with Metallic Pinhole Defects,"A three-dimensional self-consistent spin transport model is developed, which
+includes both tunnelling transport, as well as metallic transport. Using the
+spin accumulation computed either side of a tunnel barrier, spin torques are
+obtained, and it is shown the model reproduces both damping-like and field-like
+spin-transfer torques, with the expected sinusoidal angular dependence, and
+inverse ferromagnetic layer thickness dependence. An explicit solution to the
+drift-diffusion model is derived, which allows analysing the effect of both the
+reference and free layer thickness on the spin-transfer torque polarization and
+field-like coefficient. In particular, when the layers are thin, additional
+spin-dependent scattering contributions due to incomplete absorption of
+transverse spin components reduce both the damping-like and field-like spin
+torques. It is shown the model developed here can be used to compute the
+signal-to-noise ratio in realistic magnetic read-heads, where spin
+torque-induced fluctuations and instabilities limit the maximum operating
+voltage. The effect of metallic pinhole defects in the insulator layer is also
+analysed, which results in a mixture of metallic and tunnelling transport, and
+highly non-uniform charge and spin currents, requiring the full spin transport
+model to compute the resulting magneto-resistance and spin torques. Increasing
+the area covered by pinholes results in a rapid degradation of the
+magneto-resistance, following an inverse dependence. Moreover, the spin torque
+angular dependence becomes skewed, and the spin-transfer torque polarization
+decreases. The same results are obtained when considering tunnel junctions with
+a single pinhole defect, but decreasing cross-sectional area, showing that even
+a single pinhole defect can significantly degrade the performance of tunnel
+junctions and magnetic read-heads below the 40 nm node.",2209.04613v1
+2023-06-23,Nonlinear asymptotic stability and transition threshold for 2D Taylor-Couette flows in Sobolev spaces,"In this paper, we investigate the stability of the 2-dimensional (2D)
+Taylor-Couette (TC) flow for the incompressible Navier-Stokes equations. The
+explicit form of velocity for 2D TC flow is given by $u=(Ar+\frac{B}{r})(-\sin
+\theta, \cos \theta)^T$ with $(r, \theta)\in [1, R]\times \mathbb{S}^1$ being
+an annulus and $A, B$ being constants. Here, $A, B$ encode the rotational
+effect and $R$ is the ratio of the outer and inner radii of the annular region.
+Our focus is the long-term behavior of solutions around the steady 2D TC flow.
+While the laminar solution is known to be a global attractor for 2D channel
+flows and plane flows, it is unclear whether this is still true for rotating
+flows with curved geometries. In this article, we prove that the 2D
+Taylor-Couette flow is asymptotically stable, even at high Reynolds number
+($Re\sim \nu^{-1}$), with a sharp exponential decay rate of
+$\exp(-\nu^{\frac13}|B|^{\frac23}R^{-2}t)$ as long as the initial perturbation
+is less than or equal to $\nu^\frac12 |B|^{\frac12}R^{-2}$ in Sobolev space.
+The powers of $\nu$ and $B$ in this decay estimate are optimal. It is derived
+using the method of resolvent estimates and is commonly recognized as the
+enhanced dissipative effect. Compared to the Couette flow, the enhanced
+dissipation of the rotating Taylor-Couette flow not only depends on the
+Reynolds number but also reflects the rotational aspect via the rotational
+coefficient $B$. The larger the $|B|$, the faster the long-time dissipation
+takes effect. We also conduct space-time estimates describing inviscid-damping
+mechanism in our proof. To obtain these inviscid-damping estimates, we find and
+construct a new set of explicit orthonormal basis of the weighted
+eigenfunctions for the Laplace operators corresponding to the circular flows.
+These provide new insights into the mathematical understanding of the 2D
+Taylor-Couette flows.",2306.13562v1
+2023-12-18,Size dependent optical response in coupled systems of plasmons and electron-hole pairs in metallic nanostructures,"In bulk materials, the collective modes and individual modes are orthogonal
+each other, and no connection occurs if there is no damping processes. In the
+presence of damping, the collective modes, i.e., plasmons decay into the hot
+carriers. In finite systems, the collective and individual modes are coupled by
+the Coulomb interaction. Such couplings by longitudinal (L) field have been
+intensively investigated, whereas a coupling via transverse (T) field has been
+poorly studied although the plasmon is excited by an irradiated light on
+surface and in finite nanostructures. Then, the T field would play a
+significant role in the coupling between the collective and individual
+excitations. In this study, we investigate how the T field mediates the
+coherent coupling. This study is based on the recently developed microscopic
+nonlocal theory of electronic systems in metals and the results of eigenmode
+analyses by this theory. To tune the coupling strength in a single nanorod, we
+examine three parameters: Rod length $L_z$, background refractive index $n_{\rm
+b}$, and Fermi energy $\varepsilon_{\rm F}$. We discuss the modulation ratio of
+the spectrum of optical response coefficients to evaluate the coupling by the T
+field. The T field shifts the collective excitation energy, which causes a
+finite modulation at both collective excitation and individual excitations. The
+three parameters can change the energy distance between the collective and
+individual excitations. Thus, the coherent coupling by the T field is enhanced
+for a proper tuning of the parameters. The results of the investigation of
+system parameter dependence would give insight into the guiding principle of
+designing the materials for highly efficient hot carrier generation.",2312.10867v2
+2024-03-04,Cosmic-ray diffusion in two local filamentary clouds,"A fairly uniform cosmic-ray (CR) distribution is observed near the Sun,
+except in the nearby Eridu cloud, which shows an unexplained 30-50% deficit in
+GeV to TeV CR flux. To explore the origin of this deficit, we studied the
+Reticulum cloud, which shares notable traits with Eridu: a comparable distance
+in the low-density region of the Local Valley and a filamentary structure of
+atomic hydrogen extending along ordered magnetic-field lines that are steeply
+inclined to the Galactic plane. Using 14 years of Fermi-LAT data in the 0.16 to
+63 GeV energy band, we found that the gamma-ray emissivity in the Reticulum
+cloud is fully consistent with the average spectrum measured in the solar
+neighbourhood, but this emissivity, and therefore the CR flux, is 1.57 $\pm$
+0.09 times larger than in Eridu across the whole energy band. The difference
+cannot be attributed to uncertainties in gas mass. Nevertheless, we find that
+the two clouds are similar in many respects at a parsec scale: both have
+magnetic-field strengths of a few micro-Gauss in the plane of the sky; both are
+in approximate equilibrium between magnetic and thermal pressures; they have
+similar turbulent velocities and sonic Mach numbers; and both show
+magnetic-field regularity with a dispersion in orientation lower than 10-15
+degrees over large zones. The gas in Reticulum is colder and denser than in
+Eridu, but we find similar parallel diffusion coefficients around a few times
+1e28 cm2/s in both clouds if CRs above 1 GV in rigidity diffuse on resonant,
+self-excited Alfv\'en waves that are damped by ion-neutral interactions. The
+loss of CRs in Eridu remains unexplained, but these two clouds provide
+important test cases to further study how magnetic turbulence, line tangling,
+and ion-neutral damping regulate CR diffusion in the dominant gas phase of the
+interstellar medium.",2403.02466v1
+1999-04-20,Experimentally Derived Dielectronic Recombination Rate Coefficients for Heliumlike C V and Hydrogenic O VIII,"Using published measurements of dielectronic recombination (DR) resonance
+strengths and energies for C V to C IV and O VIII to O VII, we have calculated
+the DR rate coefficient for these ions. Our derived rates are in good agreement
+with multiconfiguration, intermediate-coupling and multiconfiguration,
+fully-relativistic calculations as well as with most LS coupling calculations.
+Our results are not in agreement with the recommended DR rates commonly used
+for modeling cosmic plasmas. We have used theoretical radiative recombination
+(RR) rates in conjunction with our derived DR rates to produce a total
+recombination rate for comparison with unified RR+DR calculations in LS
+coupling. Our results are not in agreement with undamped, unified calculations
+for C V but are in reasonable agreement with damped, unified calculations for O
+VIII. For C V, the Burgess general formula (GF) yields a rate which is in very
+poor agreement with our derived rate. The Burgess & Tworkowski modification of
+the GF yields a rate which is also in poor agreement. The Merts et al.
+modification of the GF yields a rate which is in fair agreement. For O VIII the
+GF yields a rate which is in fair agreement with our derived rate. The Burgess
+& Tworkowski modification of the GF yields a rate which is in good agreement.
+And the Merts et al. modification yields a rate which is in very poor
+agreement. These results suggest that for DN=1 DR it is not possible to know a
+priori which formula will yield a rate closer to the true DR rate. We describe
+the technique used to obtain DR rate coefficients from laboratory measurements
+of DR resonance strengths and energies. For use in plasma modeling, we also
+present easy-to-use fitting formulae for the experimentally derived DR rates.",9904258v1
+2016-10-12,Optical Properties Of Nanometer-Scale Structures,"Two approaches (micro- and macro- investigations) are used to determine the
+dimension dependences of the optical parameters of the nanometer-scale layers
+of materials. It is shown that both an index of refraction and coefficient of
+absorption depend strongly on the thickness of the layer. In this region of
+thicknesses, the dimension resonance occurs, where an index of refraction has a
+maximum and a coefficient of absorption has a minimum. The numerical
+calculation of the optical parameters of some materials (Ag, Al, Fe, Ge, Si,
+Se, Te) have been carried out with the use of the experimental data of
+reflection and transparency of thin layers, obtained in a series of works, and
+with our formulas for the wave amplitudes and the laws of refractions. The
+analogues of the Fresnel formulas and the Snell law have been derived from the
+Maxwell boundary conditions where the absorption and conductivity of media were
+taken into account. The use of our formulas for the wave amplitudes leads to
+the fulfillment of the conservation law of energy both for the TE- and TM-
+polarizations of light. The reemission of light is possible for the
+thicknesses, which is equal to the wavelength of light in a medium, divisible
+by integer:
+$\frac{2{\pi}d_{res}}{2}={\lambda}_m{\cdot}m=\frac{{\lambda}_0}{n}{\cdot}m$,
+where m=1,2,3... The visible luminescence of the porous silicon, silicon
+whiskers and other nanometer-scale structures can be explained by their
+emission in the case of dimension resonance because in this region of
+thicknesses, layers have a big negative coefficient of absorption and little -
+of a damping. It is also shown that in the case of the TM-polarization, in a
+material with a high conductivity, light refracts in a ""wrong"" direction (at
+all positive optical parameters) due to a surface current. In the case of the
+TE-polarization, light refracts only in a ""right"" direction.",1610.03775v1
+1992-06-18,Wormholes and Supersymmetry,"Revisions: reference added to: G. Gilbert, {\sl Nucl.Phys.} {\bf B328}, 159
+(1989)",9206072v2
+1993-05-26,Musings on Magnus,"The object of this paper is to describe a simple method for proving that
+certain groups are residually torsion-free nilpotent, to describe some new
+parafree groups and to raise some new problems in honour of the memory of
+Wilhelm Magnus.",9305201v1
+2001-10-17,Expected number of distinct part sizes in a random integer composition,"The asymptotics, as $n\to\infty$, for the expected number of distinct part
+sizes in a random composition of an integer n is obtained.",0110189v1
+2003-12-29,Non-hopfian relatively free groups,"To solve problems of Gilbert Baumslag and Hanna Neumann, posed in the 1960's,
+we construct a nontrivial variety of groups all of whose noncyclic free groups
+are non-hopfian.",0312491v1
+2005-10-26,Winning rate in the full-information best choice problem,"Following a long-standing suggestion by Gilbert and Mosteller, we derive an
+explicit formula for the asymptotic winning rate in the full-information
+problem of the best choice.",0510568v3
+2007-12-20,The dark matter as a light gravitino (II),"We address the question of gravitino dark matter in the context of gauge
+mediated supersymmetry breaking models.",0712.3465v1
+2014-02-25,Du-Hwang Characteristic Area: Catch-22,"The paper is devoted to description of two interconnected mistakes generated
+by the gap in the Du and Hwang approach to Gilbert-Pollack Steiner ratio
+conjecture.",1402.6079v1
+2016-06-01,Existence of arbitrarily smooth solutions of the LLG equation in 3D with natural boundary conditions,"We prove that the Landau-Lifshitz-Gilbert equation in three space dimensions
+with homogeneous Neumann boundary conditions admits arbitrarily smooth
+solutions, given that the initial data is sufficiently close to a constant
+function.",1606.00086v1
+2018-10-28,Asymptotic Gilbert-Varshamov bound on Frequency Hopping Sequences,"Given a $q$-ary frequency hopping sequence set of length $n$ and size $M$
+with Hamming correlation $H$, one can obtain a $q$-ary (nonlinear) cyclic code
+of length $n$ and size $nM$ with Hamming distance $n-H$. Thus, every upper
+bound on the size of a code from coding theory gives an upper bound on the size
+of a frequency hopping sequence set. Indeed, all upper bounds from coding
+theory have been converted to upper bounds on frequency hopping sequence sets
+(\cite{Ding09}). On the other hand, a lower bound from coding theory does not
+automatically produce a lower bound for frequency hopping sequence sets. In
+particular, the most important lower bound--the Gilbert-Varshamov bound in
+coding theory has not been transformed to frequency hopping sequence sets. The
+purpose of this paper is to convert the Gilbert-Varshamov bound in coding
+theory to frequency hopping sequence sets by establishing a connection between
+a special family of cyclic codes (which are called hopping cyclic codes in this
+paper) and frequency hopping sequence sets. We provide two proofs of the
+Gilbert-Varshamov bound. One is based on probabilistic method that requires
+advanced tool--martingale. This proof covers the whole rate region. The other
+proof is purely elementary but only covers part of the rate region.",1810.11757v2
+2020-05-26,Reidemeister Moves in Gauss Diagrams,"We provide a simple algorithm for recognizing and performing Reidemeister
+moves in a Gauss diagram.",2005.12957v1
+2021-05-26,Lee Weight for Nonbinary Quantum Error Correction,"We propose the quantum Lee weight for quantum errors, provide a
+Gilbert-Varshamov type bound, and a code construction for the proposed weight.",2105.12354v1
+2021-09-19,Compactness of isospectral conformal Finslerian metrics set on a 3-manifold,"Let F be a Finslerian metric on an n-dimensional closed manifold M. In this
+work, we study problems about compactness of isospectral sets of conformal
+Finslerian metrics when n=3.",2110.06338v2
+2001-05-31,Lower bound for the quantum capacity of a discrete memoryless quantum channel,"We generalize the random coding argument of stabilizer codes and derive a
+lower bound on the quantum capacity of an arbitrary discrete memoryless quantum
+channel. For the depolarizing channel, our lower bound coincides with that
+obtained by Bennett et al. We also slightly improve the quantum
+Gilbert-Varshamov bound for general stabilizer codes, and establish an analogue
+of the quantum Gilbert-Varshamov bound for linear stabilizer codes. Our proof
+is restricted to the binary quantum channels, but its extension of to l-adic
+channels is straightforward.",0105151v4
+2007-08-30,Asymptotic improvement of the Gilbert-Varshamov bound for linear codes,"The Gilbert-Varshamov bound states that the maximum size A_2(n,d) of a binary
+code of length n and minimum distance d satisfies A_2(n,d) >= 2^n/V(n,d-1)
+where V(n,d) stands for the volume of a Hamming ball of radius d. Recently
+Jiang and Vardy showed that for binary non-linear codes this bound can be
+improved to A_2(n,d) >= cn2^n/V(n,d-1) for c a constant and d/n <= 0.499. In
+this paper we show that certain asymptotic families of linear binary [n,n/2]
+random double circulant codes satisfy the same improved Gilbert-Varshamov
+bound.",0708.4164v1
+2007-09-26,Finite Element Formalism for Micromagnetism,"The aim of this work is to present the details of the finite element approach
+we developed for solving the Landau-Lifschitz-Gilbert equations in order to be
+able to treat problems involving complex geometries. There are several
+possibilities to solve the complex Landau-Lifschitz-Gilbert equations
+numerically. Our method is based on a Galerkin-type finite element approach. We
+start with the dynamic Landau-Lifschitz-Gilbert equations, the associated
+boundary condition and the constraint on the magnetization norm. We derive the
+weak form required by the finite element method. This weak form is afterwards
+integrated on the domain of calculus. We compared the results obtained with our
+finite element approach with the ones obtained by a finite difference method.
+The results being in very good agreement, we can state that our approach is
+well adapted for 2D micromagnetic systems.",0709.4153v1
+2009-05-07,Heat transport in stochastic energy exchange models of locally confined hard spheres,"We study heat transport in a class of stochastic energy exchange systems that
+characterize the interactions of networks of locally trapped hard spheres under
+the assumption that neighbouring particles undergo rare binary collisions. Our
+results provide an extension to three-dimensional dynamics of previous ones
+applying to the dynamics of confined two-dimensional hard disks [Gaspard P &
+Gilbert T On the derivation of Fourier's law in stochastic energy exchange
+systems J Stat Mech (2008) P11021]. It is remarkable that the heat conductivity
+is here again given by the frequency of energy exchanges. Moreover the
+expression of the stochastic kernel which specifies the energy exchange
+dynamics is simpler in this case and therefore allows for faster and more
+extensive numerical computations.",0905.1051v1
+2011-08-15,Hydrodynamics of self-alignment interactions with precession and derivation of the Landau-Lifschitz-Gilbert equation,"We consider a kinetic model of self-propelled particles with alignment
+interaction and with precession about the alignment direction. We derive a
+hydrodynamic system for the local density and velocity orientation of the
+particles. The system consists of the conservative equation for the local
+density and a non-conservative equation for the orientation. First, we assume
+that the alignment interaction is purely local and derive a first order system.
+However, we show that this system may lose its hyperbolicity. Under the
+assumption of weakly non-local interaction, we derive diffusive corrections to
+the first order system which lead to the combination of a heat flow of the
+harmonic map and Landau-Lifschitz-Gilbert dynamics. In the particular case of
+zero self-propelling speed, the resulting model reduces to the phenomenological
+Landau-Lifschitz-Gilbert equations. Therefore the present theory provides a
+kinetic formulation of classical micromagnetization models and spin dynamics.",1108.2951v1
+2011-09-30,"Magnetization Dynamics, Gyromagnetic Relation, and Inertial Effects","The gyromagnetic relation - i.e. the proportionality between the angular
+momentum $\vec L$ (defined by an inertial tensor) and the magnetization $\vec
+M$ - is evidence of the intimate connections between the magnetic properties
+and the inertial properties of ferromagnetic bodies. However, inertia is absent
+from the dynamics of a magnetic dipole (the Landau-Lifshitz equation, the
+Gilbert equation and the Bloch equation contain only the first derivative of
+the magnetization with respect to time). In order to investigate this
+paradoxical situation, the lagrangian approach (proposed originally by T. H.
+Gilbert) is revisited keeping an arbitrary nonzero inertial tensor. A dynamic
+equation generalized to the inertial regime is obtained. It is shown how both
+the usual gyromagnetic relation and the well-known Landau-Lifshitz-Gilbert
+equation are recovered at the kinetic limit, i.e. for time scales above the
+relaxation time $\tau$ of the angular momentum.",1109.6782v1
+2012-08-28,Decomposition of modified Landau-Lifshitz-Gilbert equation and corresponding analytic solutions,"The Suzuki-Trotter decomposition in general allows one to divide the equation
+of motion of a dynamical system into smaller parts whose integration are easier
+than the original equation. In this study, we first rewrite by employing
+feasible approximations the modified Landau-Lifshitz-Gilbert equation for
+localized spins in a suitable form for simulations using the Suzuki-Trotter
+decomposition. Next we decompose the equation into parts and demonstrate that
+the parts are classified into three groups, each of which can be solved
+exactly. Since the modified Landau-Lifshitz-Gilbert equation from which we
+start is in rather a general form, simulations of spin dynamics in various
+systems accompanying only small numerical errors are possible.",1208.5545v1
+2013-11-20,Asymptotic Improvement of the Gilbert-Varshamov Bound on the Size of Permutation Codes,"Given positive integers $n$ and $d$, let $M(n,d)$ denote the maximum size of
+a permutation code of length $n$ and minimum Hamming distance $d$. The
+Gilbert-Varshamov bound asserts that $M(n,d) \geq n!/V(n,d-1)$ where $V(n,d)$
+is the volume of a Hamming sphere of radius $d$ in $\S_n$.
+  Recently, Gao, Yang, and Ge showed that this bound can be improved by a
+factor $\Omega(\log n)$, when $d$ is fixed and $n \to \infty$. Herein, we
+consider the situation where the ratio $d/n$ is fixed and improve the
+Gilbert-Varshamov bound by a factor that is \emph{linear in $n$}. That is, we
+show that if $d/n < 0.5$, then $$ M(n,d)\geq cn\,\frac{n!}{V(n,d-1)} $$ where
+$c$ is a positive constant that depends only on $d/n$. To establish this
+result, we follow the method of Jiang and Vardy. Namely, we recast the problem
+of bounding $M(n,d)$ into a graph-theoretic framework and prove that the
+resulting graph is locally sparse.",1311.4925v1
+2016-11-21,On the List-Decodability of Random Self-Orthogonal Codes,"In 2011, Guruswami-H{\aa}stad-Kopparty \cite{Gru} showed that the
+list-decodability of random linear codes is as good as that of general random
+codes. In the present paper, we further strengthen the result by showing that
+the list-decodability of random {\it Euclidean self-orthogonal} codes is as
+good as that of general random codes as well, i.e., achieves the classical
+Gilbert-Varshamov bound. Specifically, we show that, for any fixed finite field
+$\F_q$, error fraction $\delta\in (0,1-1/q)$ satisfying $1-H_q(\delta)\le
+\frac12$ and small $\epsilon>0$, with high probability a random Euclidean
+self-orthogonal code over $\F_q$ of rate $1-H_q(\delta)-\epsilon$ is $(\delta,
+O(1/\epsilon))$-list-decodable. This generalizes the result of linear codes to
+Euclidean self-orthogonal codes. In addition, we extend the result to list
+decoding {\it symplectic dual-containing} codes by showing that the
+list-decodability of random symplectic dual-containing codes achieves the
+quantum Gilbert-Varshamov bound as well. This implies that list-decodability of
+quantum stabilizer codes can achieve the quantum Gilbert-Varshamov bound.
+  The counting argument on self-orthogonal codes is an important ingredient to
+prove our result.",1611.06673v1
+2017-11-29,Linear second-order IMEX-type integrator for the (eddy current) Landau-Lifshitz-Gilbert equation,"Combining ideas from [Alouges et al. (Numer. Math., 128, 2014)] and
+[Praetorius et al. (Comput. Math. Appl., 2017)], we propose a numerical
+algorithm for the integration of the nonlinear and time-dependent
+Landau-Lifshitz-Gilbert (LLG) equation which is unconditionally convergent,
+formally (almost) second-order in time, and requires only the solution of one
+linear system per time-step. Only the exchange contribution is integrated
+implicitly in time, while the lower-order contributions like the
+computationally expensive stray field are treated explicitly in time. Then, we
+extend the scheme to the coupled system of the Landau-Lifshitz-Gilbert equation
+with the eddy current approximation of Maxwell equations (ELLG). Unlike
+existing schemes for this system, the new integrator is unconditionally
+convergent, (almost) second-order in time, and requires only the solution of
+two linear systems per time-step.",1711.10715v1
+2017-12-28,Subquadratic time encodable codes beating the Gilbert-Varshamov bound,"We construct explicit algebraic geometry codes built from the
+Garcia-Stichtenoth function field tower beating the Gilbert-Varshamov bound for
+alphabet sizes at least 192. Messages are identied with functions in certain
+Riemann-Roch spaces associated with divisors supported on multiple places.
+Encoding amounts to evaluating these functions at degree one places. By
+exploiting algebraic structures particular to the Garcia-Stichtenoth tower, we
+devise an intricate deterministic \omega/2 < 1.19 runtime exponent encoding and
+1+\omega/2 < 2.19 expected runtime exponent randomized (unique and list)
+decoding algorithms. Here \omega < 2.373 is the matrix multiplication exponent.
+If \omega = 2, as widely believed, the encoding and decoding runtimes are
+respectively nearly linear and nearly quadratic. Prior to this work, encoding
+(resp. decoding) time of code families beating the Gilbert-Varshamov bound were
+quadratic (resp. cubic) or worse.",1712.10052v2
+2018-11-15,Hilbert-Schmidt distance and entanglement witnessing,"Gilbert proposed an algorithm for bounding the distance between a given point
+and a convex set. In this article we apply the Gilbert's algorithm to get an
+upper bound on the Hilbert-Schmidt distance between a given state and the set
+of separable states. While Hilbert Schmidt Distance does not form a proper
+entanglement measure, it can nevertheless be useful for witnessing
+entanglement. We provide here a few methods based on the Gilbert's algorithm
+that can reliably qualify a given state as strongly entangled or practically
+separable, while being computationally efficient. The method also outputs
+successively improved approximations to the Closest Separable State for the
+given state. We demonstrate the efficacy of the method with examples.",1811.06599v3
+2020-02-13,Age of Information with Gilbert-Elliot Servers and Samplers,"We study age of information in a status updating system that consists of a
+single sampler, i.e., source node, that sends time-sensitive status updates to
+a single monitor node through a server node. We first consider a Gilbert-Elliot
+service profile at the server node. In this model, service times at the server
+node follow a finite state Markov chain with two states: ${bad}$ state $b$ and
+${good}$ state $g$ where the server is faster in state $g$. We determine the
+time average age experienced by the monitor node and characterize the
+age-optimal state transition matrix $P$ with and without an average cost
+constraint on the service operation. Next, we consider a Gilbert-Elliot
+sampling profile at the source. In this model, the interarrival times follow a
+finite state Markov chain with two states: ${bad}$ state $b$ and ${good}$ state
+$g$ where samples are more frequent in state $g$. We find the time average age
+experienced by the monitor node and characterize the age-optimal state
+transition matrix $P$.",2002.05711v1
+2005-08-26,Damping of MHD turbulence in Solar Flares,"(Abridged) We describe the cascade of plasma waves or turbulence injected,
+presumably by reconnection, at scales comparable to the size of a solar flare
+loop to scales comparable to particle gyroradii, and evaluate their damping by
+various mechanisms. We show that the classical viscous damping is unimportant
+for magnetically dominated or low beta plasmas and the primary damping
+mechanism is the collisionless damping by the background particles. We show
+that the damping rate is proportional to the total random momentum density of
+the particles. For solar flare conditions this means that in most flares,
+except the very large ones, the damping is dominated by thermal background
+electrons. For large flares one requires acceleration of essentially all
+background electrons into a nonthermal distribution so that the accelerated
+electrons can be important in the damping of the waves. In general, damping by
+thermal or nonthermal protons is negligible compared to that of electrons
+except for quasi-perpendicular propagating waves or for rare proton dominated
+flares with strong nuclear gamma-ray line emission. Using the rate for damping
+we determine the critical scale below which the damping becomes important and
+the spectrum of the turbulence steepens. This critical scale, however, has
+strong dependence on the angle of propagation with respect to the magnetic
+field direction. The waves can cascade down to very small scales, such as the
+gyroradii of the particles at small angles (quasi-parallel propagation) and
+possibly near 90 degree (quasi-perpendicular propagation) giving rise to a
+highly anisotropic spectral distribution.",0508567v1
+2011-07-27,Constraint damping for the Z4c formulation of general relativity,"One possibility for avoiding constraint violation in numerical relativity
+simulations adopting free-evolution schemes is to modify the continuum
+evolution equations so that constraint violations are damped away. Gundlach et.
+al. demonstrated that such a scheme damps low amplitude, high frequency
+constraint violating modes exponentially for the Z4 formulation of General
+Relativity. Here we analyze the effect of the damping scheme in numerical
+applications on a conformal decomposition of Z4. After reproducing the
+theoretically predicted damping rates of constraint violations in the linear
+regime, we explore numerical solutions not covered by the theoretical analysis.
+In particular we examine the effect of the damping scheme on low-frequency and
+on high-amplitude perturbations of flat spacetime as well and on the long-term
+dynamics of puncture and compact star initial data in the context of spherical
+symmetry. We find that the damping scheme is effective provided that the
+constraint violation is resolved on the numerical grid. On grid noise the
+combination of artificial dissipation and damping helps to suppress constraint
+violations. We find that care must be taken in choosing the damping parameter
+in simulations of puncture black holes. Otherwise the damping scheme can cause
+undesirable growth of the constraints, and even qualitatively incorrect
+evolutions. In the numerical evolution of a compact static star we find that
+the choice of the damping parameter is even more delicate, but may lead to a
+small decrease of constraint violation. For a large range of values it results
+in unphysical behavior.",1107.5539v2
+1999-11-24,Damped Lyman alpha absorber and the faint end of the galaxy luminosity function at high redshift,"We combine predictions for several hierarchical cosmogonies with
+observational evidence on damped Lyman alpha systems to establish a
+correspondence between the high redshift galaxy population and the properties
+of damped Lyman alpha systems. We assume that high redshift galaxies and damped
+Lyman alpha systems are hosted by the same dark matter halos and require
+consistency between the predicted halo space density, the rate of incidence and
+the velocity width distribution of damped Lyman alpha systems, and the observed
+galaxy luminosity function at the bright end. We arrive at the following
+results: (1) predicted impact parameters between the damped absorption system
+and the luminous part of the absorbing galaxy are expected to be very small
+(0.3 - 1arcsec) for most galaxies; (2) luminosities of galaxies causing damped
+absorption are generally fainter than m_R = 25 and damped Lyman alpha systems
+are predicted to sample preferentially the outer regions of galaxies at the
+faint end of the galaxy luminosity function at high redshift. Therefore, DLAS
+should currently provide the best probe of the progenitors of normal
+present-day galaxies.",9911447v1
+2003-03-13,An explicit unconditionally stable numerical method for solving damped nonlinear Schrödinger equations with a focusing nonlinearity,"This paper introduces an extension of the time-splitting sine-spectral (TSSP)
+method for solving damped focusing nonlinear Schr\""{o}dinger equations (NLS).
+The method is explicit, unconditionally stable and time transversal invariant.
+Moreover, it preserves the exact decay rate for the normalization of the wave
+function if linear damping terms are added to the NLS. Extensive numerical
+tests are presented for cubic focusing nonlinear Schr\""{o}dinger equations in
+2d with a linear, cubic or a quintic damping term. Our numerical results show
+that quintic or cubic damping always arrests blowup, while linear damping can
+arrest blowup only when the damping parameter $\dt$ is larger than a threshold
+value $\dt_{\rm th}$. We note that our method can also be applied to solve the
+3d Gross-Pitaevskii equation with a quintic damping term to model the dynamics
+of a collapsing and exploding Bose-Einstein condensate (BEC).",0303158v1
+2004-11-03,Quantum probability applied to the damped harmonic oscillator,"In this introductory course we sketch the framework of quantum probability in
+order to discuss open quantum systems, in particular the damped harmonic
+oscillator.",0411024v1
+2006-11-23,Path integrals and wavepacket evolution for damped mechanical systems,"Damped mechanical systems with various forms of damping are quantized using
+the path integral formalism. In particular, we obtain the path integral kernel
+for the linearly damped harmonic oscillator and a particle in a uniform
+gravitational field with linearly or quadratically damped motion. In each case,
+we study the evolution of Gaussian wavepackets and discuss the characteristic
+features that help us distinguish between different types of damping. For
+quadratic damping, we show that the action and equation of motion of such a
+system has a connection with the zero dimensional version of a currently
+popular scalar field theory. Furthermore we demonstrate that the equation of
+motion (for quadratic damping) can be identified as a geodesic equation in a
+fictitious two-dimensional space.",0611239v1
+2007-07-05,Damping of bulk excitations over an elongated BEC - the role of radial modes,"We report the measurement of Beliaev damping of bulk excitations in cigar
+shaped Bose Einstein condensates of atomic vapor. By using post selection,
+excitation line shapes of the total population are compared with those of the
+undamped excitations. We find that the damping depends on the initial
+excitation energy of the decaying quasi particle, as well as on the excitation
+momentum. We model the condensate as an infinite cylinder and calculate the
+damping rates of the different radial modes. The derived damping rates are in
+good agreement with the experimentally measured ones. The damping rates
+strongly depend on the destructive interference between pathways for damping,
+due to the quantum many-body nature of both excitation and damping products.",0707.0776v1
+2008-09-22,Damping in 2D and 3D dilute Bose gases,"Damping in 2D and 3D dilute gases is investigated using both the
+hydrodynamical approach and the Hartree-Fock-Bogoliubov (HFB) approximation .
+We found that the both methods are good for the Beliaev damping at zero
+temperature and Landau damping at very low temperature, however, at high
+temperature, the hydrodynamical approach overestimates the Landau damping and
+the HFB gives a better approximation. This result shows that the comparison of
+the theoretical calculation using the hydrodynamical approach and the
+experimental data for high temperature done by Vincent Liu (PRL {\bf21} 4056
+(1997)) is not proper. For two-dimensional systems, we show that the Beliaev
+damping rate is proportional to $k^3$ and the Landau damping rate is
+proportional to $ T^2$ for low temperature and to $T$ for high temperature. We
+also show that in two dimensions the hydrodynamical approach gives the same
+result for zero temperature and for low temperature as HFB, but overestimates
+the Landau damping for high temperature.",0809.3632v3
+2008-12-08,Landau Damping and Alfven Eigenmodes of Neutron Star Torsion Oscillations,"Torsion oscillations of the neutron star crust are Landau damped by the
+Alfven continuum in the bulk. For strong magnetic fields (in magnetars),
+undamped Alfven eigenmodes appear.",0812.1570v1
+2010-09-24,Spatial Damping of Propagating Kink Waves in Prominence Threads,"Transverse oscillations and propagating waves are frequently observed in
+threads of solar prominences/filaments and have been interpreted as kink
+magnetohydrodynamic (MHD) modes. We investigate the spatial damping of
+propagating kink MHD waves in transversely nonuniform and partially ionized
+prominence threads. Resonant absorption and ion-neutral collisions (Cowling's
+diffusion) are the damping mechanisms taken into account. The dispersion
+relation of resonant kink waves in a partially ionized magnetic flux tube is
+numerically solved by considering prominence conditions. Analytical expressions
+of the wavelength and damping length as functions of the kink mode frequency
+are obtained in the Thin Tube and Thin Boundary approximations. For typically
+reported periods of thread oscillations, resonant absorption is an efficient
+mechanism for the kink mode spatial damping, while ion-neutral collisions have
+a minor role. Cowling's diffusion dominates both the propagation and damping
+for periods much shorter than those observed. Resonant absorption may explain
+the observed spatial damping of kink waves in prominence threads. The
+transverse inhomogeneity length scale of the threads can be estimated by
+comparing the observed wavelengths and damping lengths with the theoretically
+predicted values. However, the ignorance of the form of the density profile in
+the transversely nonuniform layer introduces inaccuracies in the determination
+of the inhomogeneity length scale.",1009.4871v1
+2012-08-01,Artificial Neural Network Based Prediction of Optimal Pseudo-Damping and Meta-Damping in Oscillatory Fractional Order Dynamical Systems,"This paper investigates typical behaviors like damped oscillations in
+fractional order (FO) dynamical systems. Such response occurs due to the
+presence of, what is conceived as, pseudo-damping and meta-damping in some
+special class of FO systems. Here, approximation of such damped oscillation in
+FO systems with the conventional notion of integer order damping and time
+constant has been carried out using Genetic Algorithm (GA). Next, a multilayer
+feed-forward Artificial Neural Network (ANN) has been trained using the GA
+based results to predict the optimal pseudo and meta-damping from knowledge of
+the maximum order or number of terms in the FO dynamical system.",1208.0318v1
+2012-08-27,Optimization of the damped quantum search,"The damped quantum search proposed in [A. Mizel, Phys. Rev. Lett., 102 150501
+(2009)] was analyzed by calculating the highest possible probability of finding
+the target state in each iteration. A new damping parameter that depends on the
+number of iterations was obtained, this was compared to the critical damping
+parameter for different values of target to database size ratio. The result
+shows that the range of the new damping parameter as a function of the target
+to database size ratio increases as the number of iterations is increased.
+Furthermore, application of the new damping parameter per iteration on the
+damped quantum search scheme shows a significant improvement on some target to
+database size ratio (i.e. greater than or equal to 50% maximum percentage
+difference) over the critically damped quantum search.",1208.5475v1
+2013-04-03,Damping the zero-point energy of a harmonic oscillator,"The physics of quantum electromagnetism in an absorbing medium is that of a
+field of damped harmonic oscillators. Yet until recently the damped harmonic
+oscillator was not treated with the same kind of formalism used to describe
+quantum electrodynamics in a arbitrary medium. Here we use the techniques of
+macroscopic QED, based on the Huttner--Barnett reservoir, to describe the
+quantum mechanics of a damped oscillator. We calculate the thermal and
+zero-point energy of the oscillator for a range of damping values from zero to
+infinity. While both the thermal and zero-point energies decrease with damping,
+the energy stored in the oscillator at fixed temperature increases with
+damping, an effect that may be experimentally observable. As the results follow
+from canonical quantization, the uncertainty principle is valid for all damping
+levels.",1304.0977v2
+2015-05-28,Damping factors for head-tail modes at strong space charge,"This paper suggests how feedback and Landau damping can be taken into account
+for transverse oscillations of bunched beam at strong space charge.",1505.07704v1
+2015-06-18,Damping of MHD turbulence in partially ionized plasma: implications for cosmic ray propagation,"We study the damping from neutral-ion collisions of both incompressible and
+compressible magnetohydrodynamic (MHD) turbulence in partially ionized medium.
+We start from the linear analysis of MHD waves applying both single-fluid and
+two-fluid treatments. The damping rates derived from the linear analysis are
+then used in determining the damping scales of MHD turbulence. The physical
+connection between the damping scale of MHD turbulence and cutoff boundary of
+linear MHD waves is investigated. Our analytical results are shown to be
+applicable in a variety of partially ionized interstellar medium (ISM) phases
+and solar chromosphere. As a significant astrophysical utility, we introduce
+damping effects to propagation of cosmic rays in partially ionized ISM. The
+important role of turbulence damping in both transit-time damping and
+gyroresonance is identified.",1506.05585v1
+2016-02-04,Damping Evaluation for Free Vibration of Spherical Structures in Elastodynamic-Acoustic Interaction,"This paper discusses the free vibration of elastic spherical structures in
+the presence of an externally unbounded acoustic medium. In this vibration,
+damping associated with the radiation of energy from the confined solid medium
+to the surrounding acoustic medium is observed. Evaluating the coupled system
+response (solid displacement and acoustic pressure) and characterizing the
+acoustic radiation damping in conjunction with the media properties are the
+main objectives of this research. In this work, acoustic damping is
+demonstrated for two problems: the thin spherical shell and the solid sphere.
+The mathematical approach followed in solving these coupled problems is based
+on the Laplace transform method. The linear under-damped harmonic oscillator is
+the reference model for damping estimation. The damping evaluation is performed
+in frequency as well as in time domains; both investigations lead to identical
+damping factor expressions.",1604.06738v1
+2017-09-05,Enhancement of space-charge induced damping due to reactive impedances for head-tail modes,"Landau damping of head-tail modes in bunches due to spreads in the tune shift
+can be a deciding factor for beam stability. We demonstrate that the coherent
+tune shifts due to reactive impedances can enhance the space-charge induced
+damping and change the stability thresholds (here, a reactive impedance implies
+the imaginary part of the impedance of both signs). For example, high damping
+rates at strong space-charge, or damping of the $k=0$ mode, can be possible. It
+is shown and explained, how the negative reactive impedances (causing negative
+coherent tune shifts similarly to the effect of space-charge) can enhance the
+Landau damping, while the positive coherent tune shifts have an opposite
+effect. It is shown that the damping rate is a function of the coherent mode
+position in the incoherent spectrum, in accordance with the concept of the
+interaction of a collective mode with resonant particles. We present an
+analytical model, which allows for quantitative predictions of damping
+thresholds for different head-tail modes, for arbitrary space-charge and
+coherent tune-shift conditions, as it is verified using particle tracking
+simulations.",1709.01425v1
+2018-05-21,Critical damping in nonviscously damped linear systems,"In structural dynamics, energy dissipative mechanisms with non-viscous
+damping are characterized by their dependence on the time-history of the
+response velocity, mathematically represented by convolution integrals
+involving hereditary functions. Combination of damping parameters in the
+dissipative model can lead the system to be overdamped in some (or all) modes.
+In the domain of the damping parameters, the thresholds between induced
+oscillatory and non--oscillatory motion are called critical damping surfaces
+(or manifolds, since we can have a lot of parameters). In this paper a general
+method to obtain critical damping surfaces for nonviscously damped systems is
+proposed. The approach is based on transforming the algebraic equations which
+defined implicitly the critical curves into a system of differential equations.
+The derivations are validated with three numerical methods covering single and
+multiple degree of freedom systems.",1805.08022v1
+2018-11-01,Hereditary effects of exponentially damped oscillators with past histories,"Hereditary effects of exponentially damped oscillators with past histories
+are considered in this paper. Nonviscously damped oscillators involve
+hereditary damping forces which depend on time-histories of vibrating motions
+via convolution integrals over exponentially decaying functions. As a result,
+this kind of oscillators are said to have memory. In this work, initialization
+for nonviscously damped oscillators is firstly proposed. Unlike the classical
+viscously damped ones, information of the past history of response velocity is
+necessary to fully determine the dynamic behaviors of nonviscously damped
+oscillators. Then, initialization response of exponentially damped oscillators
+is obtained to characterize the hereditary effects on the dynamic response. At
+last, stability of initialization response is proved and the hereditary effects
+are shown to gradually recede with increasing of time.",1811.00216v1
+2019-08-01,The Temperature-dependent Damping of Propagating Slow Magnetoacoustic Waves,"The rapid damping of slow magnetoacoustic waves in the solar corona has been
+extensively studied in previous years. Most studies suggest that thermal
+conduction is a dominant contributor to this damping, albeit with a few
+exceptions. Employing extreme-ultraviolet (EUV) imaging data from SDO/AIA, we
+measure the damping lengths of propagating slow magnetoacoustic waves observed
+in several fan-like loop structures using two independent methods. The
+dependence of the damping length on temperature has been studied for the first
+time. The results do not indicate any apparent decrease in damping length with
+temperature, which is in contrast to the existing viewpoint. Comparing with the
+corresponding theoretical values calculated from damping due to thermal
+conduction, it is inferred that thermal conduction is suppressed in hotter
+loops. An alternative interpretation that suggests thermal conduction is not
+the dominant damping mechanism, even for short period waves in warm active
+region loops, is also presented.",1908.00384v1
+2019-10-14,Decay rates for the damped wave equation with finite regularity damping,"Decay rates for the energy of solutions of the damped wave equation on the
+torus are studied. In particular, damping invariant in one direction and equal
+to a sum of squares of nonnegative functions with a particular number of
+derivatives of regularity is considered. For such damping energy decays at rate
+$1/t^{2/3}$. If additional regularity is assumed the decay rate improves. When
+such a damping is smooth the energy decays at $1/t^{4/5-\delta}$. The proof
+uses a positive commutator argument and relies on a pseudodifferential calculus
+for low regularity symbols.",1910.06372v3
+2022-07-01,Seismic Response of Yielding Structures Coupled to Rocking Walls with Supplemental Damping,"Given that the coupling of a framing structure to a strong, rocking wall
+enforces a first-mode response, this paper investigates the dynamic response of
+a yielding single-degree-of-freedom oscillator coupled to a rocking wall with
+supplemental damping (hysteretic or linear viscous) along its sides. The full
+nonlinear equations of motion are derived, and the study presents an earthquake
+response analysis in term of inelastic spectra. The study shows that for
+structures with preyielding period T1<1.0 s the effect of supplemental damping
+along the sides of the rocking wall is marginal even when large values of
+damping are used. The study uncovers that occasionally the damped response
+matches or exceeds the undamped response; however, when this happens, the
+exceedance is marginal. The paper concludes that for yielding structures with
+strength less than 10% of their weight the use of supplemental damping along
+the sides of a rocking wall coupled to a yielding structure is not recommended.
+The paper shows that supplemental damping along the sides of the rocking wall
+may have some limited beneficial effects for structures with longer preyielding
+periods (say T1>1.0 s). Nevertheless, no notable further response reduction is
+observed when larger values of hysteretic or viscous damping are used.",2207.00641v1
+2023-03-08,Material-Geometry Interplay in Damping of Biomimetic Scale Beams,"Biomimetic scale-covered substrates are architected meta-structures
+exhibiting fascinating emergent nonlinearities via the geometry of collective
+scales contacts. In spite of much progress in understanding their elastic
+nonlinearity, their dissipative behavior arising from scales sliding is
+relatively uninvestigated in the dynamic regime. Recently discovered is the
+phenomena of viscous emergence, where dry Coulomb friction between scales can
+lead to apparent viscous damping behavior of the overall multi-material
+substrate. In contrast to this structural dissipation, material dissipation
+common in many polymers has never been considered, especially synergestically
+with geometrical factors. This is addressed here for the first time, where
+material visco-elasticity is introduced via a simple Kelvin-Voigt model for
+brevity and clarity. The results contrast the two damping sources in these
+architectured systems: material viscoelasticity, and geometrical frictional
+scales contact. It is discovered that although topically similar in effective
+damping, viscoelsatic damping follows a different damping envelope than dry
+friction, including starkly different effects on damping symmetry and specific
+damping capacity.",2303.04920v1
+2023-04-11,A comparison of 7 Tesla MR spectroscopic imaging and 3 Tesla MR fingerprinting for tumor localization in glioma patients,"This paper investigates the correlation between magnetic resonance
+spectroscopic imaging (MRSI) and magnetic resonance fingerprinting (MRF) in
+glioma patients by comparing neuro-oncological markers obtained from MRSI to
+T1/T2 maps from MRF.
+  Data from 12 consenting patients with gliomas were analyzed by defining
+hotspots for T1, T2 and various metabolic ratios, and comparing them using
+S{\o}rensen-Dice Similarity Coefficients (DSCs) and the distances between their
+centers of intensity (COIDs).
+  Median DSCs between MRF and the tumor segmentation were 0.73 (T1) and 0.79
+(T2). The DSCs between MRSI and MRF were highest for Gln/tNAA (T1: 0.75, T2:
+0.80, tumor: 0.78), followed by Gly/tNAA (T1: 0.57, T2: 0.62, tumor: 0.54) and
+tCho/tNAA (T1: 0.61, T2: 0.58, tumor: 0.45). The median values in the tumor
+hotspot were T1=1724 ms, T2=86 ms, Gln/tNAA=0.61, Gly/tNAA=0.28, Ins/tNAA=1.15,
+and tCho/tNAA=0.48, and, in the peritumoral region, were T1=1756 ms, T2=102ms,
+Gln/tNAA=0.38, Gly/tNAA=0.20, Ins/tNAA=1.06, and tCho/tNAA=0.38, and, in the
+NAWM, were T1=950 ms, T2=43 ms, Gln/tNAA=0.16, Gly/tNAA=0.07, Ins/tNAA=0.54,
+and tCho/tNAA=0.20.
+  The results of this study constitute the first comparison of 7T MRSI and 3T
+MRF, showing a good correspondence between these methods.",2304.05254v1
+1998-03-28,Landau damping and the echo effect in a confined Bose-Einstein condensate,"Low energy collective mode of a confined Bose-Einstein condensate should
+demonstrate the echo effect in the regime of Landau damping. This echo is a
+signature of reversible nature of Landau damping. General expression for the
+echo profile is derived in the limit of small amplitudes of the external
+pulses. Several universal features of the echo are found. The existence of echo
+in other cases of reversible damping -- Fano effect and Caldeira-Leggett model
+-- is emphasized. It is suggested to test reversible nature of the damping in
+the atomic traps by conducting the echo experiment.",9803351v1
+2000-07-10,Dephasing of Electrons on Helium by Collisions with Gas Atoms,"The damping of quantum effects in the transport properties of electrons
+deposited on a surface of liquid helium is studied. It is found that due to
+vertical motion of the helium vapour atoms the interference of paths of
+duration $t$ is damped by a factor $\exp - (t/\tau_v)^3$. An expression is
+derived for the weak-localization lineshape in the case that damping occurs by
+a combination of processes with this type of cubic exponential damping and
+processes with a simple exponential damping factor.",0007160v1
+1997-10-07,Damping rate of plasmons and photons in a degenerate nonrelativistic plasma,"A calculation is presented of the plasmon and photon damping rates in a dense
+nonrelativistic plasma at zero temperature, following the resummation program
+of Braaten-Pisarski. At small soft momentum $k$, the damping is dominated by $3
+\to 2$ scattering processes corresponding to double longitudinal Landau
+damping. The dampings are proportional to $(\alpha/v_{F})^{3/2} k^2/m$, where
+$v_{F}$ is the Fermi velocity.",9710260v1
+2002-12-16,Influence of damping on the vanishing of the electro-optic effect in chiral isotropic media,"Using first principles, it is demonstrated that radiative damping alone
+cannot lead to a nonvanishing electro-optic effect in a chiral isotropic
+medium. This conclusion is in contrast with that obtained by a calculation in
+which damping effects are included using the standard phenomenological model.
+We show that these predictions differ because the phenomenological damping
+equations are valid only in regions where the frequencies of the applied
+electromagnetic fields are nearly resonant with the atomic transitions. We also
+show that collisional damping can lead to a nonvanishing electrooptic effect,
+but with a strength sufficiently weak that it is unlikely to be observable
+under realistic laboratory conditions.",0212089v1
+2005-08-28,Simultaneous amplitude and phase damping of a kind of Gaussian states and their separability,"We give out the time evolution solution of simultaneous amplitude and phase
+damping for any continuous variable state. For the simultaneous amplitude and
+phase damping of a wide class of two- mode entangled Gaussian states, two
+analytical conditions of the separability are given. One is the sufficient
+condition of separability. The other is the condition of PPT separability where
+the Peres-Horodecki criterion is applied. Between the two conditions there may
+exist bound entanglement. The simplest example is the simultaneous amplitude
+and phase damping of a two-mode squeezed vacuum state. The damped state is
+non-Gaussian.",0508209v2
+2007-05-14,"Identification of the dominant precession damping mechanism in Fe, Co, and Ni by first-principles calculations","The Landau-Lifshitz equation reliably describes magnetization dynamics using
+a phenomenological treatment of damping. This paper presents first-principles
+calculations of the damping parameters for Fe, Co, and Ni that quantitatively
+agree with existing ferromagnetic resonance measurements. This agreement
+establishes the dominant damping mechanism for these systems and takes a
+significant step toward predicting and tailoring the damping constants of new
+materials.",0705.1990v1
+2007-08-28,Ising Dynamics with Damping,"We show for the Ising model that is possible construct a discrete time
+stochastic model analogous to the Langevin equation that incorporates an
+arbitrary amount of damping. It is shown to give the correct equilibrium
+statistics and is then used to investigate nonequilibrium phenomena, in
+particular, magnetic avalanches. The value of damping can greatly alter the
+shape of hysteresis loops, and for small damping and high disorder, the
+morphology of large avalanches can be drastically effected. Small damping also
+alters the size distribution of avalanches at criticality.",0708.3855v1
+2008-02-08,On the scaling of the damping time for resonantly damped oscillations in coronal loops,"There is not as yet full agreement on the mechanism that causes the rapid
+damping of the oscillations observed by TRACE in coronal loops. It has been
+suggested that the variation of the observed values of the damping time as
+function of the corresponding observed values of the period contains
+information on the possible damping mechanism. The aim of this Letter is to
+show that, for resonant absorption, this is definitely not the case unless
+detailed a priori information on the individual loops is available.",0802.1143v1
+2008-10-02,Critically damped quantum search,"Although measurement and unitary processes can accomplish any quantum
+evolution in principle, thinking in terms of dissipation and damping can be
+powerful. We propose a modification of Grover's algorithm in which the idea of
+damping plays a natural role. Remarkably, we have found that there is a
+critical damping value that divides between the quantum $O(\sqrt{N})$ and
+classical O(N) search regimes. In addition, by allowing the damping to vary in
+a fashion we describe, one obtains a fixed-point quantum search algorithm in
+which ignorance of the number of targets increases the number of oracle queries
+only by a factor of 1.5.",0810.0470v1
+2009-07-01,Modal approximations to damped linear systems,"We consider a finite dimensional damped second order system and obtain
+spectral inclusion theorems for the related quadratic eigenvalue problem. The
+inclusion sets are the 'quasi Cassini ovals' which may greatly outperform
+standard Gershgorin circles. As the unperturbed system we take a modally damped
+part of the system; this includes the known proportionally damped models, but
+may give much sharper estimates. These inclusions are then applied to derive
+some easily calculable sufficient conditions for the overdampedness of a given
+damped system.",0907.0167v1
+2010-01-14,Multi-Error-Correcting Amplitude Damping Codes,"We construct new families of multi-error-correcting quantum codes for the
+amplitude damping channel. Our key observation is that, with proper encoding,
+two uses of the amplitude damping channel simulate a quantum erasure channel.
+This allows us to use concatenated codes with quantum erasure-correcting codes
+as outer codes for correcting multiple amplitude damping errors. Our new codes
+are degenerate stabilizer codes and have parameters which are better than the
+amplitude damping codes obtained by any previously known construction.",1001.2356v1
+2011-09-05,Spectral theory of damped quantum chaotic systems,"We investigate the spectral distribution of the damped wave equation on a
+compact Riemannian manifold, especially in the case of a metric of negative
+curvature, for which the geodesic flow is Anosov. The main application is to
+obtain conditions (in terms of the geodesic flow on $X$ and the damping
+function) for which the energy of the waves decays exponentially fast, at least
+for smooth enough initial data. We review various estimates for the high
+frequency spectrum in terms of dynamically defined quantities, like the value
+distribution of the time-averaged damping. We also present a new condition for
+a spectral gap, depending on the set of minimally damped trajectories.",1109.0930v1
+2012-06-07,From resolvent estimates to damped waves,"In this paper we show how to obtain decay estimates for the damped wave
+equation on a compact manifold without geometric control via knowledge of the
+dynamics near the un-damped set. We show that if replacing the damping term
+with a higher-order \emph{complex absorbing potential} gives an operator
+enjoying polynomial resolvent bounds on the real axis, then the ""resolvent""
+associated to our damped problem enjoys bounds of the same order. It is known
+that the necessary estimates with complex absorbing potential can also be
+obtained via gluing from estimates for corresponding non-compact models.",1206.1565v1
+2012-12-03,Inviscid limit of stochastic damped 2D Navier-Stokes equations,"We consider the inviscid limit of the stochastic damped 2D Navier- Stokes
+equations. We prove that, when the viscosity vanishes, the stationary solution
+of the stochastic damped Navier-Stokes equations converges to a stationary
+solution of the stochastic damped Euler equation and that the rate of
+dissipation of enstrophy converges to zero. In particular, this limit obeys an
+enstrophy balance. The rates are computed with respect to a limit measure of
+the unique invariant measure of the stochastic damped Navier-Stokes equations.",1212.0509v3
+2014-01-13,NLSE for quantum plasmas with the radiation damping,"We consider contribution of the radiation damping in the quantum hydrodynamic
+equations for spinless particles. We discuss possibility of obtaining of
+corresponding non-linear Schrodinger equation (NLSE) for the macroscopic wave
+function. We compare contribution of the radiation damping with weakly (or
+semi-) relativistic effects appearing in the second order by v/c. The radiation
+damping appears in the third order by v/c. So it might be smaller than weakly
+relativistic effects, but it gives damping of the Langmuir waves which can be
+considerable.",1401.2829v1
+2014-09-26,An ultimate storage ring lattice with vertical emittance generated by damping wigglers,"We discuss the approach of generating round beams for ultimate storage rings
+using vertical damping wigglers (with horizontal magnetic field). The vertical
+damping wigglers provide damping and excite vertical emittance. This eliminates
+the need to generate large linear coupling that is impractical with traditional
+off-axis injection. We use a PEP-X compatible lattice to demonstrate the
+approach. This lattice uses separate quadrupole and sextupole magnets with
+realistic gradient strengths. Intrabeam scattering effects are calculated. The
+horizontal and vertical emittances are 22.3 pm and 10.3 pm, respectively, for a
+200 mA, 4.5 GeV beam, with a vertical damping wiggler of a total length of 90
+meters, peak field of 1.5 T and wiggler period of 100 mm.",1409.7452v2
+2017-03-01,Behaviors of the energy of solutions of two coupled wave equations with nonlinear damping on a compact manifold with boundary,"In this paper we study the behaviors of the the energy of solutions of
+coupled wave equations on a compact manifold with boundary in the case of
+indirect nonlinear damping . Only one of the two equations is directly damped
+by a localized nonlinear damping term. Under geometric conditions on both the
+coupling and the damping regions we prove that the rate of decay of the energy
+of smooth solutions of the system is determined from a first order differential
+equation .",1703.00172v1
+2017-06-02,Vanishing viscosity limit for global attractors for the damped Navier--Stokes system with stress free boundary conditions,"We consider the damped and driven Navier--Stokes system with stress free
+boundary conditions and the damped Euler system in a bounded domain
+$\Omega\subset\mathbf{R}^2$. We show that the damped Euler system has a
+(strong) global attractor in~$H^1(\Omega)$. We also show that in the vanishing
+viscosity limit the global attractors of the Navier--Stokes system converge in
+the non-symmetric Hausdorff distance in $H^1(\Omega)$ to the the strong global
+attractor of the limiting damped Euler system (whose solutions are not
+necessarily unique).",1706.00607v1
+2018-01-20,Long time dynamics for weakly damped nonlinear Klein-Gordon equations,"We continue our study of damped nonlinear Klein-Gordon equations. In our
+previous work we considered fixed positive damping and proved a form of the
+soliton resolution conjecture for radial solutions. In contrast, here we
+consider damping which decreases in time to 0. In the class of radial data we
+again establish soliton resolution provided the damping goes to 0 sufficiently
+slowly. While our previous work relied on invariant manifold theory, here we
+use the Lojasiewicz-Simon inequality applied to a suitable Lyapunov functional.",1801.06735v1
+2018-02-28,Nonexistence of global solutions of wave equations with weak time-dependent damping and combined nonlinearity,"In our previous two works, we studied the blow-up and lifespan estimates for
+damped wave equations with a power nonlinearity of the solution or its
+derivative, with scattering damping independently. In this work, we are devoted
+to establishing a similar result for a combined nonlinearity. Comparing to the
+result of wave equation without damping, one can say that the scattering
+damping has no influence.",1802.10273v1
+2018-11-12,Choking non-local magnetic damping in exchange biased ferromagnets,"We investigated the temperature dependence of the magnetic damping in the
+exchange biased Pt/ Fe50Mn50 /Fe20Ni80 /SiOx multilayers. In samples having a
+strong exchange bias, we observed a drastic decrease of the magnetic damping of
+the FeNi with increasing temperature up to the blocking temperature. The
+results essentially indicate that the non-local enhancement of the magnetic
+damping can be choked by the adjacent antiferromagnet and its temperature
+dependent exchange bias. We also pointed out that such a strong temperature
+dependent damping may be very beneficial for spintronic applications.",1811.04821v1
+2019-05-23,Escaping Locally Optimal Decentralized Control Polices via Damping,"We study the evolution of locally optimal decentralized controllers with the
+damping of the control system. Empirically it is shown that even for instances
+with an exponential number of connected components, damping merges all local
+solutions to the one global solution. We characterize the evolution of locally
+optimal solutions with the notion of hemi-continuity and further derive
+asymptotic properties of the objective function and of the locally optimal
+controllers as the damping becomes large. Especially, we prove that with enough
+damping, there is no spurious locally optimal controller with favorable control
+structures. The convoluted behavior of the locally optimal trajectory is
+illustrated with numerical examples.",1905.09915v1
+2019-08-22,Some remarks on the asymptotic profile of solutions to structurally damped $σ$-evolution equations,"In this paper, we are interested in analyzing the asymptotic profiles of
+solutions to the Cauchy problem for linear structurally damped
+$\sigma$-evolution equations in $L^2$-sense. Depending on the parameters
+$\sigma$ and $\delta$ we would like to not only indicate approximation formula
+of solutions but also recognize the optimality of their decay rates as well in
+the distinct cases of parabolic like damping and $\sigma$-evolution like
+damping. Moreover, such results are also discussed when we mix these two kinds
+of damping terms in a $\sigma$-evolution equation to investigate how each of
+them affects the asymptotic profile of solutions.",1908.08492v1
+2019-09-18,Global smooth solutions of the damped Boussinesq equations with a class of large initial data,"The global regularity problem concerning the inviscid Boussinesq equations
+remains an open problem. In an attempt to understand this problem, we examine
+the damped Boussinesq equations and study how damping affects the regularity of
+solutions. In this paper, we consider the global existence to the damped
+Boussinesq equations with a class of large initial data, whose $B^{s}_{p,r}$ or
+$\dot{B}^{s}_{p,r}$ norms can be arbitrarily large. The idea is splitting the
+linear Boussinesq equations from the damped Boussinesq equations, the
+exponentially decaying solution of the former equations together with the
+structure of the Boussinesq equations help us to obtain the global smooth
+solutions.",1909.08360v1
+2020-02-15,Asymptotic profile and optimal decay of solutions of some wave equations with logarithmic damping,"We introduce a new model of the nonlocal wave equations with a logarithmic
+damping mechanism. We consider the Cauchy poroblem for the new model in the
+whole space. We study the asymptotic profile and optimal decay and blowup rates
+of solutions as time goes to infinity. The damping terms considered in this
+paper is not studied so far, and in the low frequency parameters the damping is
+rather weakly effective than that of well-studied fractional type of nonlocal
+damping. In order to get the optimal estimates in time we meet the so-called
+hypergeometric functions with special parameters.",2002.06319v1
+2020-05-13,Weak Input to state estimates for 2D damped wave equations with localized and non-linear damping,"In this paper, we study input-to-state (ISS) issues for damped wave equations
+with Dirichlet boundary conditions on a bounded domain of dimension two. The
+damping term is assumed to be non-linear and localized to an open subset of the
+domain. In a first step, we handle the undisturbed case as an extension of a
+previous work, where stability results are given with a damping term active on
+the full domain. Then, we address the case with disturbances and provide
+input-to-state types of results.",2005.06206v3
+2020-07-25,Decay for the Kelvin-Voigt damped wave equation: Piecewise smooth damping,"We study the energy decay rate of the Kelvin-Voigt damped wave equation with
+piecewise smooth damping on the multi-dimensional domain. Under suitable
+geometric assumptions on the support of the damping, we obtain the optimal
+polynomial decay rate which turns out to be different from the one-dimensional
+case studied in \cite{LR05}. This optimal decay rate is saturated by high
+energy quasi-modes localised on geometric optics rays which hit the interface
+along non orthogonal neither tangential directions. The proof uses
+semi-classical analysis of boundary value problems.",2007.12994v2
+2020-08-12,From Lieb-Thirring inequalities to spectral enclosures for the damped wave equation,"Using a correspondence between the spectrum of the damped wave equation and
+non-self-adjoint Schroedinger operators, we derive various bounds on complex
+eigenvalues of the former. In particular, we establish a sharp result that the
+one-dimensional damped wave operator is similar to the undamped one provided
+that the L^1 norm of the (possibly complex-valued) damping is less than 2. It
+follows that these small dampings are spectrally undetectable.",2008.05176v1
+2021-08-02,Wide-Area Damping Control for Interarea Oscillations in Power Grids Based on PMU Measurements,"In this paper, a phasor measurement unit (PMU)-based wide-area damping
+control method is proposed to damp the interarea oscillations that threaten the
+modern power system stability and security. Utilizing the synchronized PMU
+data, the proposed almost model-free approach can achieve an effective damping
+for the selected modes using a minimum number of synchronous generators.
+Simulations are performed to show the validity of the proposed wide-area
+damping control scheme.",2108.01193v1
+2021-09-05,Regularity of the semigroups associated with some damped coupled elastic systems II: a nondegenerate fractional damping case,"In this paper, we examine regularity issues for two damped abstract elastic
+systems; the damping and coupling involve fractional powers $\mu, \theta$, with
+$0 \leq \mu , \theta \leq 1$, of the principal operators. The matrix defining
+the coupling and damping is nondegenerate. This new work is a sequel to the
+degenerate case that we discussed recently in \cite{kfl}. First, we prove that
+for $1/2 \leq \mu , \theta \leq 1$, the underlying semigroup is analytic. Next,
+we show that for $\min(\mu,\theta) \in (0,1/2)$, the semigroup is of certain
+Gevrey classes. Finally, some examples of application are provided.",2109.02044v1
+2021-09-28,A robust and efficient line search for self-consistent field iterations,"We propose a novel adaptive damping algorithm for the self-consistent field
+(SCF) iterations of Kohn-Sham density-functional theory, using a backtracking
+line search to automatically adjust the damping in each SCF step. This line
+search is based on a theoretically sound, accurate and inexpensive model for
+the energy as a function of the damping parameter. In contrast to usual damped
+SCF schemes, the resulting algorithm is fully automatic and does not require
+the user to select a damping. We successfully apply it to a wide range of
+challenging systems, including elongated supercells, surfaces and
+transition-metal alloys.",2109.14018v3
+2021-11-17,Spectral asymptotics for the vectorial damped wave equation,"The eigenfrequencies associated to a scalar damped wave equation are known to
+belong to a band parallel to the real axis. In [Sj{\""o}00] J. Sj{\""o}strand
+showed that up to a set of density 0, the eigenfrequencies are confined in a
+thinner band determined by the Birkhoff limits of the damping term. In this
+article we show that this result is still true for a vectorial damped wave
+equation. In this setting the Lyapunov exponents of the cocycle given by the
+damping term play the role of the Birkhoff limits of the scalar setting.",2111.08982v1
+2021-12-13,Rotons and their damping in elongated dipolar Bose-Einstein condensates,"We discuss finite temperature damping of rotons in elongated Bose-condensed
+dipolar gases, which are in the Thomas-Fermi regime in the tightly confined
+directions. The presence of many branches of excitations which can participate
+in the damping process, is crucial for the Landau damping and results in
+significant increase of the damping rate. It is found, however, that even
+rotons with energies close to the roton gap may remain fairly stable in systems
+with the roton gap as small as 1nK.",2112.06835v2
+2022-03-12,Asymptotic expansion of solutions to the wave equation with space-dependent damping,"We study the large time behavior of solutions to the wave equation with
+space-dependent damping in an exterior domain. We show that if the damping is
+effective, then the solution is asymptotically expanded in terms of solutions
+of corresponding parabolic equations. The main idea to obtain the asymptotic
+expansion is the decomposition of the solution of the damped wave equation into
+the solution of the corresponding parabolic problem and the time derivative of
+the solution of the damped wave equation with certain inhomogeneous term and
+initial data. The estimate of the remainder term is an application of weighted
+energy method with suitable supersolutions of the corresponding parabolic
+problem.",2203.06360v1
+2022-10-27,Sharp polynomial decay for polynomially singular damping on the torus,"We study energy decay rates for the damped wave equation with unbounded
+damping, without the geometric control condition. Our main decay result is
+sharp polynomial energy decay for polynomially controlled singular damping on
+the torus. We also prove that for normally $L^p$-damping on compact manifolds,
+the Schr\""odinger observability gives $p$-dependent polynomial decay, and
+finite time extinction cannot occur. We show that polynomially controlled
+singular damping on the circle gives exponential decay.",2210.15697v3
+2023-09-27,Dispersion and damping of ion-acoustic waves in the plasma with a regularized kappa-distribution,"The dispersion and damping of ion-acoustic waves in the plasma with a
+regularized kappa-distribution are studied. The generalized dispersion relation
+and damping rate are derived, which both depend significantly on the parameters
+alpha and kappa. The numerical analyses show that the wave frequency and the
+damping rate of ion-acoustic waves in the plasma with the regularized
+kappa-distribution are both generally less than those in the plasma with the
+kappa-distribution, and if kappa is less than a value, the ion-acoustic waves
+and their damping rate exist in the plasma with the regularized
+kappa-distribution.",2309.15885v1
+2023-11-16,Near-optimal Closed-loop Method via Lyapunov Damping for Convex Optimization,"We introduce an autonomous system with closed-loop damping for first-order
+convex optimization. While, to this day, optimal rates of convergence are only
+achieved by non-autonomous methods via open-loop damping (e.g., Nesterov's
+algorithm), we show that our system is the first one featuring a closed-loop
+damping while exhibiting a rate arbitrarily close to the optimal one. We do so
+by coupling the damping and the speed of convergence of the system via a
+well-chosen Lyapunov function. We then derive a practical first-order algorithm
+called LYDIA by discretizing our system, and present numerical experiments
+supporting our theoretical findings.",2311.10053v1
+2024-02-05,Fractional damping induces resonant behavior in the Duffing oscillator,"The interaction between the fractional order parameter and the damping
+parameter can play a relevant role for introducing different dynamical
+behaviors in a physical system. Here, we study the Duffing oscillator with a
+fractional damping term. Our findings show that for certain values of the
+fractional order parameter, the damping parameter, and the forcing amplitude
+high oscillations amplitude can be induced. This phenomenon is due to the
+appearance of a resonance in the Duffing oscillator only when the damping term
+is fractional.",2402.02940v1
+2024-03-13,Impact of Decoherence on Average Correlation,"This article presents a comprehensive study of the impact of decoherence on
+the average correlation for pure quantum states. We explore two primary
+mechanisms of decoherence: phase damping and amplitude damping, each having
+distinct effects on quantum systems. Phase damping, which describes the loss of
+quantum coherence without energy loss, primarily affects the phase
+relationships between the components of a quantum system while amplitude
+damping involves energy dissipation and also affects the state's occupation
+probabilities. We show that the average correlation follows a predictable
+decaying pattern in both scenarios. Our analysis can be understood in the
+context of quantum computing, by focusing on how phase damping influences the
+entanglement and correlation between qubits, key factors in quantum
+computational efficiency and error correction protocols.",2403.10551v1
+1998-02-18,Damping rates of hot Giant Dipole Resonances,"The damping rate of hot giant dipole resonances (GDR) is investigated.
+Besides Landau damping we consider collisions and density fluctuations as
+contributions to the damping of GDR. Within the nonequilibrium Green's function
+method we derive a non-Markovian kinetic equation. The linearization of the
+latter one leads to complex dispersion relations. The complex solution provides
+the centroid energy and the damping width of giant resonances. The experimental
+damping widths are the full width half maximum (FWHM) and can be reproduced by
+the full width of the structure function. Within simple finite size scaling we
+give a relation between the minimal interaction strength which is required for
+a collective oscillation and the clustersize. We investigate the damping of
+giant dipole resonances within a Skyrme type of interaction. Different
+collision integrals are compared with each other in order to incorporate
+correlations. The inclusion of a conserving relaxation time approximation
+allows to find the $T^2$-dependence of the damping rate with a temperature
+known from the Fermi-liquid theory. However, memory effects turn out to be
+essential for a proper treatment of the damping of collective modes. We derive
+a Landau like formula for the one--particle relaxation time similar to the
+damping of zero sound.",9802052v2
+2015-12-11,Ultra-low magnetic damping of a metallic ferromagnet,"The phenomenology of magnetic damping is of critical importance for devices
+that seek to exploit the electronic spin degree of freedom since damping
+strongly affects the energy required and speed at which a device can operate.
+However, theory has struggled to quantitatively predict the damping, even in
+common ferromagnetic materials. This presents a challenge for a broad range of
+applications in spintronics and spin-orbitronics that depend on materials and
+structures with ultra-low damping. Such systems enable many experimental
+investigations that further our theoretical understanding of numerous magnetic
+phenomena such as damping and spin-transport mediated by chirality and the
+Rashba effect. Despite this requirement, it is believed that achieving
+ultra-low damping in metallic ferromagnets is limited due to the scattering of
+magnons by the conduction electrons. However, we report on a binary alloy of Co
+and Fe that overcomes this obstacle and exhibits a damping parameter
+approaching 0.0001, which is comparable to values reported only for
+ferrimagnetic insulators. We explain this phenomenon by a unique feature of the
+bandstructure in this system: The density of states exhibits a sharp minimum at
+the Fermi level at the same alloy concentration at which the minimum in the
+magnetic damping is found. This discovery provides both a significant
+fundamental understanding of damping mechanisms as well as a test of
+theoretical predictions.",1512.03610v1
+2020-05-12,Effective Viscous Damping Enables Morphological Computation in Legged Locomotion,"Muscle models and animal observations suggest that physical damping is
+beneficial for stabilization. Still, only a few implementations of mechanical
+damping exist in compliant robotic legged locomotion. It remains unclear how
+physical damping can be exploited for locomotion tasks, while its advantages as
+sensor-free, adaptive force- and negative work-producing actuators are
+promising. In a simplified numerical leg model, we studied the energy
+dissipation from viscous and Coulomb damping during vertical drops with
+ground-level perturbations. A parallel spring-damper is engaged between
+touch-down and mid-stance, and its damper auto-disengages during mid-stance and
+takeoff. Our simulations indicate that an adjustable and viscous damper is
+desired. In hardware we explored effective viscous damping and adjustability
+and quantified the dissipated energy. We tested two mechanical, leg-mounted
+damping mechanisms; a commercial hydraulic damper, and a custom-made pneumatic
+damper. The pneumatic damper exploits a rolling diaphragm with an adjustable
+orifice, minimizing Coulomb damping effects while permitting adjustable
+resistance. Experimental results show that the leg-mounted, hydraulic damper
+exhibits the most effective viscous damping. Adjusting the orifice setting did
+not result in substantial changes of dissipated energy per drop, unlike
+adjusting damping parameters in the numerical model. Consequently, we also
+emphasize the importance of characterizing physical dampers during real legged
+impacts to evaluate their effectiveness for compliant legged locomotion.",2005.05725v2
+2022-02-10,Non-stationary Anderson acceleration with optimized damping,"Anderson acceleration (AA) has a long history of use and a strong recent
+interest due to its potential ability to dramatically improve the linear
+convergence of the fixed-point iteration. Most authors are simply using and
+analyzing the stationary version of Anderson acceleration (sAA) with a constant
+damping factor or without damping. Little attention has been paid to
+nonstationary algorithms. However, damping can be useful and is sometimes
+crucial for simulations in which the underlying fixed-point operator is not
+globally contractive. The role of this damping factor has not been fully
+understood. In the present work, we consider the non-stationary Anderson
+acceleration algorithm with optimized damping (AAoptD) in each iteration to
+further speed up linear and nonlinear iterations by applying one extra
+inexpensive optimization. We analyze this procedure and develop an efficient
+and inexpensive implementation scheme. We also show that, compared with the
+stationary Anderson acceleration with fixed window size sAA(m), optimizing the
+damping factors is related to dynamically packaging sAA(m) and sAA(1) in each
+iteration (alternating window size $m$ is another direction of producing
+non-stationary AA). Moreover, we show by extensive numerical experiments that
+the proposed non-stationary Anderson acceleration with optimized damping
+procedure often converges much faster than stationary AA with constant damping
+or without damping.",2202.05295v1
+2023-06-30,A finite element method to compute the damping rate of oscillating fluids inside microfluidic nozzles,"We introduce a finite element method for computing the damping rate of fluid
+oscillations in nozzles of drop-on-demand (DoD) microfluidic devices. Accurate
+knowledge of the damping rates for the least-damped oscillation modes following
+droplet ejection is paramount for assessing jetting stability at higher jetting
+frequencies, as ejection from a non-quiescent meniscus can result in deviations
+from nominal droplet properties. Computational fluid dynamics (CFD) simulations
+often struggle to accurately predict meniscus damping in the limit of low
+viscosity and high surface tension. Moreover, their use in design loops aimed
+at optimizing the nozzle geometry for stable jetting is slow and
+computationally expensive. The faster alternative we adopt here is to compute
+the damping rate directly from the eigenvalues of the linearized problem.
+Starting from a variational formulation of the linearized governing equations,
+we obtain a generalized eigenvalue problem for the oscillation modes, and
+approximate its solutions with a finite element method that uses Taylor-Hood
+elements. We solve the matrix eigenvalue problem with a sparse, parallelized
+implementation of the Krylov-Schur algorithm. The spatial shape and temporal
+evolution (angular frequency and damping rate) of the set of least-damped
+oscillation modes are obtained in a matter of minutes, compared to days for a
+CFD simulation. We verify that the method can reproduce an analytical benchmark
+problem, and then determine numerical convergence rates on two examples with
+axisymmetric geometry. We also prove that the method is free of spurious modes
+with zero or positive damping rates. The method's ability to quickly generate
+accurate estimates of fluid oscillation damping rates makes it suitable for
+integration into design loops for prototyping microfluidic nozzles.",2307.00094v1
+2024-01-18,Multithermal apparent damping of slow waves due to strands with a Gaussian temperature distribution,"Context. Slow waves in solar coronal loops are strongly damped. The current
+theory of damping by thermal conduction cannot explain some observational
+features.\n Aims. We investigate the propagation of slow waves in a coronal
+loop built up from strands of different temperatures. \n Methods. We consider
+the loop to have a multithermal, Gaussian temperature distribution. The
+different propagation speeds in different strands lead to an multithermal
+apparent damping of the wave, similar to observational phase mixing. We use an
+analytical model to predict the damping length and propagation speed for the
+slow waves, including in imaging with filter telescopes. \n Results. We compare
+the damping length due to this multithermal apparent damping with damping due
+to thermal conduction and find that the multithermal apparent damping is more
+important for shorter period slow waves. We have found the influence of
+instrument filters on the wave's propagation speed and damping. This allows us
+to compare our analytical theory to forward models of numerical simulations. \n
+Conclusions. We find that our analytical model matches the numerical
+simulations very well. Moreover, we offer an outlook for using the slow wave
+properties to infer the loop's thermal properties.",2401.09803v1
+2001-03-09,Rayleigh Scattering and Microwave Background Fluctuations,"During the recombination epoch, cosmic background photons couple not only to
+free electrons through Thompson scattering, but also to the neutral hydrogen
+through Rayleigh scattering. This latter is ~2% effect for photons near the
+peak of the photon energy distribution at z=800 and a ~0.2% effect at z=1100.
+Including Rayleigh scattering in the calculation reduces Silk damping at fixed
+redshift, alters the position of the surface of last scattering and alters the
+propagation of acoustic waves. We estimate the amplitude of these effects. For
+the Microwave Anisotropy Probe (MAP), Rayleigh scattering increases the
+anisotropy spectrum by 0.1% at the most. For the highest frequencies of the
+Planck Surveyor, the effects of Rayleigh scattering are much more dramatic
+(decreasing the anisotropy spectrum by 3% at \nu~550GHz and l~1000). The
+relative difference between the spectra of low and high frequencies is imposed
+by an oscillation with a function of multipole l and the oscillation amplitude
+is up to 0.5% between 100 and 550GHz. Rayleigh scattering also slows the
+decoupling between radiation and matter, but the effect is undetectably small.",0103149v3
+2001-03-19,Fluctuations in the Cosmic Microwave Background II: $C_\ell$ at Large and Small $\ell$,"General asymptotic formulas are given for the coefficient $C_\ell$ of the
+term of multipole number $\ell$ in the temperature correlation function of the
+cosmic microwave background, in terms of scalar and dipole form factors
+introduced in a companion paper. The formulas apply in two overlapping limits:
+for $\ell\gg 1$ and for $\ell d/d_A\ll 1$ (where $d_A$ is the angular diameter
+distance of the surface of last scattering, and $d$ is a length, of the order
+of the acoustic horizon at the time of last scattering, that characterizes
+acoustic oscillations before this time.) The frequently used approximation that
+$C_\ell$ receives its main contribution from wave numbers of order $\ell/d_A$
+is found to be less accurate for the contribution of the Doppler effect than
+for the Sachs--Wolfe effect and intrinsic temperature fluctuations. For $\ell
+d/d_A\ll 1$ and $\ell\geq 2$, the growth of $C_\ell$ with $\ell$ is shown to be
+affected by acoustic oscillation wave numbers of all scales. The asymptotic
+formulas are applied to a model of acoustic oscillations before the time of
+last scattering, with results in reasonable agreement with more elaborate
+computer calculations.",0103281v2
+2003-01-22,Propagation model for cosmic ray species in the Galaxy,"In a recent paper (Moskalenko et al., 2002), it has been shown that the flux
+of secondary cosmic ray (CR) antiprotons appears to be contradictory to
+measurements of secondary to primary nuclei ratios in cosmic rays when
+calculated in the same Galactic propagation model. The contradiction appears as
+a value of the diffusion coefficient necessary to match the secondary ratios
+antiproton/proton and B/C. In particlular, it was shown that the reacceleration
+models designed to match secondary to primary nuclei ratios produce too few
+antiprotons. It is, however, clear that some reacceleration is unavoidable in
+the turbulent interstellar medium. Here we discuss an idea of how to improve
+reacceleration model by allowing for the damping of interstellar turbulences on
+the small scale by cosmic rays, mostly protons. This would lead to increase in
+the mean free path lenghts at low energies, the well-known phenomena
+empirically discovered in the Leaky Box models, thus producing less secondary
+nuclei. Antiprotons will remain almost non-affected due to their high energy
+threshold of production cross section.",0301420v1
+2005-02-28,On the existence of three-dimensional hydrostatic and magnetostatic equilibria of self-gravitating fluid bodies,"(Abridged) We develop an analytical spectral method to solve the equations of
+equilibrium for a self-gravitating, magnetized fluid body, under the only
+hypotheses that (a) the equation of state is isothermal, (b) the configuration
+is scale-free, and (c) the body is electrically neutral. All physical variables
+are represented as series of scalar and vector spherical harmonics of degree l
+and order m, and the equilibrium equations are reduced to a set of coupled
+quadratic algebraic equations for the expansion coefficients of the density and
+the magnetic vector potential. The method is general, and allows to recover
+previously known hydrostatic and magnetostatic solutions possessing axial
+symmetry. A linear perturbation analysis of the equations in spectral form show
+that these basic axisymmetric states, considered as a continuos sequence with
+the relative amount of magnetic support as control parameter, have in general
+no neighboring nonaxisymmetric equilibria. This result lends credence to a
+conjecture originally made by H. Grad and extends early results obtained by E.
+Parker to the case of self-gravitating magnetized bodies. The only allowed
+bifurcations of this sequence of axisymmetric equilibria are represented by
+distortions with dipole-like angular dependence (l=1) that can be continued
+into the nonlinear regime. These new configurations are either (i) azimuthally
+asymmetric (m=+-1) or (ii) azimuthally symmetric but without reflection
+symmetry with respect to the equatorial plane (m=0). To the extent that
+interstellar clouds can be represented as isolated magnetostatic equilibria,
+the results of this study suggest that the observed triaxial shapes of
+molecular cloud cores can be interpreted in terms of weakly damped Alfven
+oscillations about an equilibrium state.",0502584v1
+2006-06-14,Electron Acceleration in Solar Flares: Theory of Spectral Evolution,"Context: Stochastic acceleration is thought to be a key mechanism in the
+energization of solar flare electrons.
+  Aims: We study whether stochastic acceleration can reproduce the observed
+soft-hard-soft evolution of the spectral features of the hard X-ray emitted by
+suprathermal electron. We pay special attention to the effects of particle
+trapping and escape.
+  Methods: The Fokker-Planck equation for the electron distribution is
+integrated numerically using the coefficients derived by Miller et al. for
+transit-time damping acceleration. The electron spectra are then converted to
+photon spectra for comparison with RHESSI observation of looptop sources.
+  Results: The presence of particle escape softens the model spectra computed
+in the stochastic acceleration framework. The ratio between the efficiency of
+trapping and acceleration controls the spectral evolution which follows a
+soft-hard-soft pattern. Furthermore, a pivot point (that is, a common crossing
+point of the accelerated particle spectra at different times) is found at
+around 10 keV. It can be brought into agreement with the observed value of 20
+keV by enhanced trapping through an electric potential.
+  Conclusions: The model proposed here accounts for the key features observed
+in the spectral evolution of hard X-ray emission from looptop sources.",0606339v2
+1996-07-04,Continuous Elastic Phase Transitions in Pure and Disordered Crystals,"We review the theory of second--order (ferro--)elastic phase transitions,
+where the order parameter consists of a certain linear combination of strain
+tensor components, and the accompanying soft mode is an acoustic phonon. In
+three--dimensional crystals, the softening can occur in one-- or
+two--dimensional soft sectors. The ensuing anisotropy reduces the effect of
+fluctuations, rendering the critical behaviour of these systems classical for a
+one--dimensional soft sector, and classical with logarithmic corrections in
+case of a two--dimensional soft sector. The dynamical critical exponent is $z =
+2$, and as a consequence the sound velocity vanishes as $c_s \propto | T - T_c
+|^{1/2}$, while the phonon damping coefficient is essentially
+temperature--independent. Disorder may lead to a variety of precursor effects
+and modified critical behaviour. Defects that locally soften the crystal may
+induce the phenomenon of local order parameter condensation. When the
+correlation length of the pure system exceeds the average defect separation
+$n_{\rm D}^{-1/3}$, a disorder--induced phase transition to a state with
+non--zero average order parameter can occur at a temperature $T_c(n_{\rm D})$
+well above the transition temperature $T_c^0$ of the pure crystal. Near
+$T_c^0$, the order--parameter curve, susceptibility, and specific heat appear
+rounded. For $T < T_c(n_{\rm D})$ the spatial inhomogeneity induces a static
+central peak with finite $q$ width in the scattering cross section, accompanied
+by a dynamical component that is confined to the very vicinity of the
+disorder--induced phase transition.",9607028v2
+2004-03-28,Bilayer Membrane in Confined Geometry: Interlayer Slide and Steric Repulsion,"We derived free energy functional of a bilayer lipid membrane from the first
+principles of elasticity theory. The model explicitly includes
+position-dependent mutual slide of monolayers and bending deformation. Our free
+energy functional of liquid-crystalline membrane allows for incompressibility
+of the membrane and vanishing of the in-plane shear modulus and obeys
+reflectional and rotational symmetries of the flat bilayer. Interlayer slide at
+the mid-plane of the membrane results in local difference of surface densities
+of the monolayers. The slide amplitude directly enters free energy via the
+strain tensor. For small bending deformations the ratio between bending modulus
+and area compression coefficient, Kb/KA, is proportional to the square of
+monolayer thickness, h. Using the functional we performed self-consistent
+calculation of steric potential acting on bilayer between parallel confining
+walls separated by distance 2d. We found that temperature-dependent curvature
+at the minimum of confining potential is enhanced four times for a bilayer with
+slide as compared with a unit bilayer. We also calculate viscous modes of
+bilayer membrane between confining walls. Pure bending of the membrane is
+investigated, which is decoupled from area dilation at small amplitudes. Three
+sources of viscous dissipation are considered: water and membrane viscosities
+and interlayer drag. Dispersion has two branches. Confinement between the walls
+modifies the bending mode with respect to membrane in bulk solution.
+Simultaneously, inter-layer slipping mode, damped by viscous drag, remains
+unchanged by confinement.",0403676v1
+1995-06-26,A Stochastic Approach to Thermal Fluctuations during a First Order Electroweak Phase Transition,"We investigate the role played by subcritical bubbles at the onset of the
+electroweak phase transition. Treating the configuration modelling the thermal
+fluctuations around the homogeneous zero configuration of the Higgs field as a
+stochastic variable, we describe its dynamics by a phenomenological Langevin
+equation. This approach allows to properly take into account both the effects
+of the thermal bath on the system: a systematic dyssipative force, which tends
+to erase out any initial subcritical configuration, and a random stochastic
+force responsible for the fluctuations. We show that the contribution to the
+variance $\lgh\phi^2(t)\rg_V$ in a given volume $V$ from any initial
+subcritical configuration is quickly damped away and that, in the limit of long
+times, $\lgh\phi^2(t)\rg_V$ approaches its equilibrium value provided by the
+stochastic force and independent from the viscosity coefficient, as predicted
+by the fluctuation-dissipation theorem. In agreement with some recent claims,
+we conclude that thermal fluctuations do not affect the nucleation of critical
+bubbles at the onset of the electroweak phase transition making electroweak
+baryogenesis scenarios still a viable possibility to explain the primordial
+baryon asymmetry in the Universe.",9506419v1
+1995-10-26,Classical and quantum many-body description of bremsstrahlung in dense matter (Landau - Pomeranchuk - Migdal effect),"Some considerations about the importance of coherence effects for
+bremsstrahlung processes in non--equilibrium dense matter (Landau - Pomeranchuk
+- Migdal - effect) are presented. They are of particular relevance for the
+application to photon - and di-lepton production from high energy nuclear
+collisions, to gluon radiation in QCD transport, or parton kinetics and to
+neutrino and axion radiation from supernova explosion and from hot neutron
+stars. The soft behavior of the bremsstrahlung from a source described by
+classical transport models is discussed and pocket correction formulas for the
+in-matter radiation cross sections are suggested in terms of standard transport
+coefficients. The radiation rates are also discussed within a non--equilibrium
+quantum field theory (Schwinger - Kadanoff - Baym - Keldysh) formulation. A
+classification of diagrams and corresponding resummation in physically
+meaningful terms is proposed, which considers the finite damping width of all
+source particles in matter. This way each diagram in this expansion is already
+free from the infra--red divergences. Both, the correct quasi--particle and
+quasi--classical limits are recovered from this subset of graphs. Explicit
+results are given for dense matter in thermal equilibrium. The diagrammatic
+description may suggest a formulation of a transport theory that includes the
+propagation of off--shell particles in non--equilibrium dense matter.",9510417v1
+1997-10-15,Domain Walls Out of Equilibrium,"We study the non-equilibrium dynamics of domain walls in real time for
+$\phi^4$ and Sine Gordon models in 1+1 dimensions in the dilute regime. The
+equation of motion for the collective coordinate is obtained by integrating out
+the meson excitations around the domain wall to one-loop order. The real-time
+non-equilibrium relaxation is studied analytically and numerically to this
+order. The constant friction coefficient vanishes but there is dynamical
+friction and relaxation caused by off-shell non-Markovian effects. The validity
+of a Markovian description is studied in detail. The proper Langevin equation
+is obtained to this order, the noise is Gaussian and additive but colored. We
+analyze the classical and hard thermal loop contributions to the self-energy
+and noise kernels and show that at temperatures larger than the meson mass the
+hard contributions are negligible and the finite temperature contribution to
+the dynamics is governed by the classical soft modes of the meson bath. The
+long time relaxational dynamics is completely dominated by classical Landau
+damping resulting in that the corresponding time scales are not set by the
+temperature but by the meson mass. The noise correlation function and the
+dissipative kernel obey a generalized form of the Fluctuation-Dissipation
+relation.",9710359v2
+2005-01-06,Non-statistical fluctuations for deep inelastic processes in 27Al + 27Al,"The excitation functions for different fragments produced in the 27Al + 27Al
+dissipative collisions have been measured in steps of 250 keV in the energy
+range 122 - 132 MeV. Deep inelastic processes have been selected by integrating
+events over a total kinetic energy loss window of 12 MeV between 20 and 32 MeV.
+Large fluctuations have been observed in all the studied excitation functions.
+Non-satistical origin of these fluctuations is confirmed by large channel cross
+correlations coefficients. Energy autocorrelation function of cross section
+excitation function presents damped oscillation structure as predicted for the
+case when a di-nuclear system with a lifetime similar with its revolution
+period is formed. The periodicity of the energy autocorrelation function is
+used to obtain information on the deformation of the 27Al + 27 Al di-nucleus.",0501003v1
+2004-10-14,Cold Strongly Coupled Atoms Make a Near-perfect Liquid,"Feshbach resonances of trapped ultracold alkali atoms allow to vary the
+atomic scattering length a. At very large values of a the system enters an
+universal strongly coupled regime in which its properties--the ground state
+energy, pressure {\it etc.}--become independent of a. We discuss transport
+properties of such systems. In particular, the universality arguments imply
+that the shear viscosity of ultracold Fermi atoms at the Feschbach resonance is
+proportional to the particle number density n, and the Plank constant \hbar
+\eta=\hbar n \alpha_\eta, where \alpha_\eta is a universal constant. Using
+Heisenberg uncertainty principle and Einstein's relation between diffusion and
+viscosity we argue that the viscosity has the lower bound given by
+\alpha_{\eta} \leq (6\pi)^{-1}. We relate the damping of low-frequency density
+oscillations of ultracold optically trapped ^{6}Li atoms to viscosity and find
+that the value of the coefficient \alpha_\eta is about 0.3. We also show that
+such a small viscosity can not be explained by kinetic theory based on binary
+scattering. We conclude that the system of ultracold atoms near the Feshbach
+resonance is a near-ideal liquid.",0410067v2
+1996-08-14,Ginzburg-Landau-Gor'kov Theory of Magnetic oscillations in a type-II 2-dimensional Superconductor,"We investigate de Haas-van Alphen (dHvA) oscillations in the mixed state of a
+type-II two-dimensional superconductor within a self-consistent Gor'kov
+perturbation scheme. Assuming that the order parameter forms a vortex lattice
+we can calculate the expansion coefficients exactly to any order. We have
+tested the results of the perturbation theory to fourth and eight order against
+an exact numerical solution of the corresponding Bogoliubov-de Gennes
+equations. The perturbation theory is found to describe the onset of
+superconductivity well close to the transition point $H_{c2}$. Contrary to
+earlier calculations by other authors we do not find that the perturbative
+scheme predicts any maximum of the dHvA-oscillations below $H_{c2}$. Instead we
+obtain a substantial damping of the magnetic oscillations in the mixed state as
+compared to the normal state. We have examined the effect of an oscillatory
+chemical potential due to particle conservation and the effect of a finite
+Zeeman splitting. Furthermore we have investigated the recently debated issue
+of a possibility of a sign change of the fundamental harmonic of the magnetic
+oscillations. Our theory is compared with experiment and we have found good
+agreement.",9608004v3
+2007-10-04,Detailed Examination of Transport Coefficients in Cubic-Plus-Quartic Oscillator Chains,"We examine the thermal conductivity and bulk viscosity of a one-dimensional
+(1D) chain of particles with cubic-plus-quartic interparticle potentials and no
+on-site potentials. This system is equivalent to the FPU-alpha beta system in a
+subset of its parameter space. We identify three distinct frequency regimes
+which we call the hydrodynamic regime, the perturbative regime and the
+collisionless regime. In the lowest frequency regime (the hydrodynamic regime)
+heat is transported ballistically by long wavelength sound modes. The model
+that we use to describe this behaviour predicts that as the frequency goes to
+zero the frequency dependent bulk viscosity and the frequency dependent thermal
+conductivity should diverge with the same power law dependence on frequency.
+Thus, we can define the bulk Prandtl number as the ratio of the bulk viscosity
+to the thermal conductivity (with suitable prefactors to render it
+dimensionless). This dimensionless ratio should approach a constant value as
+frequency goes to zero. We use mode-coupling theory to predict the zero
+frequency limit. Values of the bulk Prandtl number from simulations are in
+agreement with these predictions over a wide range of system parameters. In the
+middle frequency regime, which we call the perturbative regime, heat is
+transported by sound modes which are damped by four-phonon processes. We call
+the highest frequency regime the collisionless regime since at these
+frequencies the observing times are much shorter than the characteristic
+relaxation times of phonons. The perturbative and collisionless regimes are
+discussed in detail in the appendices.",0710.1066v1
+2008-01-01,Radiative torques alignment in the presence of pinwheel torques,"We study the alignment of grains subject to both radiative torques and
+pinwheel torques while accounting for thermal flipping of grains. By pinwheel
+torques we refer to all systematic torques that are fixed in grain body axes,
+including the radiative torques arising from scattering and absorption of
+isotropic radiation. We discuss new types of pinwheel torques, which are
+systematic torques arising from infrared emission and torques arising from the
+interaction of grains with ions and electrons in hot plasma. We show that both
+types of torques are long-lived, i.e. may exist longer than gaseous damping
+time. We compare these torques with the torques introduced by E. Purcell,
+namely, torques due to H$_2$ formation, the variation of accommodation
+coefficient for gaseous collisions and photoelectric emission. Furthermore, we
+revise the Lazarian & Draine model for grain thermal flipping. We calculate
+mean flipping timescale induced by Barnett and nuclear relaxation for both
+paramagnetic and superparamagnetic grains, in the presence of stochastic
+torques associated with pinwheel torques, e.g. the stochastic torques arising
+from H$_2$ formation, and gas bombardment. We show that the combined effect of
+internal relaxation and stochastic torques can result in fast flipping for
+sufficiently small grains and, because of this, they get thermally trapped,
+i.e. rotate thermally in spite of the presence of pinwheel torques. For
+sufficiently large grains, we show that the pinwheel torques can increase the
+degree of grain alignment achievable with the radiative torques by increasing
+the magnitude of the angular momentum of low attractor points and/or by driving
+grains to new high attractor points.",0801.0266v2
+2008-09-09,Turbulent Convection in Stellar Interiors. II. The Velocity Field,"We analyze stellar convection with the aid of 3D hydrodynamic simulations,
+introducing the turbulent cascade into our theoretical analysis. We devise
+closures of the Reynolds-decomposed mean field equations by simple physical
+modeling of the simulations (we relate temperature and density fluctuations via
+coefficients); the procedure (CABS, Convection Algorithms Based on Simulations)
+is terrestrially testable and is amenable to systematic improvement. We develop
+a turbulent kinetic energy equation which contains both nonlocal and time
+dependent terms, and is appropriate if the convective transit time is shorter
+than the evolutionary time scale. The interpretation of mixing-length theory
+(MLT) as generally used in astrophysics is incorrect; MLT forces the mixing
+length to be an imposed constant. Direct tests show that the damping associated
+with the flow is that suggested by Kolmogorov. The eddy size is approximately
+the depth of the convection zone, and this dissipation length corresponds to
+the ""mixing length"". New terms involving local heating by turbulent dissipation
+should appear in the stellar evolution equations. The enthalpy flux
+(""convective luminosity"") is directly connected to the buoyant acceleration,
+and hence the velocity scale. MLT tends to systematically underestimate this
+velocity scale. Quantitative comparison with a variety of 3D simulations
+reveals a previously recognized consistency. Examples of application to stellar
+evolution will be presented in subsequent papers in this series.",0809.1625v2
+2011-04-04,The underlying physical meaning of the $ν_{\rm max}-ν_{\rm c}$ relation,"Asteroseismology of stars that exhibit solar-like oscillations are enjoying a
+growing interest with the wealth of observational results obtained with the
+CoRoT and Kepler missions. In this framework, scaling laws between
+asteroseismic quantities and stellar parameters are becoming essential tools to
+study a rich variety of stars. However, the physical underlying mechanisms of
+those scaling laws are still poorly known. Our objective is to provide a
+theoretical basis for the scaling between the frequency of the maximum in the
+power spectrum ($\nu_{\rm max}$) of solar-like oscillations and the cut-off
+frequency ($\nu_{\rm c}$). Using the SoHO GOLF observations together with
+theoretical considerations, we first confirm that the maximum of the height in
+oscillation power spectrum is determined by the so-called \emph{plateau} of the
+damping rates. The physical origin of the plateau can be traced to the
+destabilizing effect of the Lagrangian perturbation of entropy in the
+upper-most layers which becomes important when the modal period and the local
+thermal relaxation time-scale are comparable. Based on this analysis, we then
+find a linear relation between $\nu_{\rm max}$ and $\nu_{\rm c}$, with a
+coefficient that depends on the ratio of the Mach number of the exciting
+turbulence to the third power to the mixing-length parameter.",1104.0630v2
+2012-04-09,Global MRI with Braginskii viscosity in a galactic profile,"We present a global-in-radius linear analysis of the axisymmetric
+magnetorotational instability (MRI) in a collisional magnetized plasma with
+Braginskii viscosity. For a galactic angular velocity profile $\Omega$ we
+obtain analytic solutions for three magnetic field orientations: purely
+azimuthal, purely vertical and slightly pitched (almost azimuthal). In the
+first two cases the Braginskii viscosity damps otherwise neutrally stable
+modes, and reduces the growth rate of the MRI respectively. In the final case
+the Braginskii viscosity makes the MRI up to $2\sqrt{2}$ times faster than its
+inviscid counterpart, even for \emph{asymptotically small} pitch angles. We
+investigate the transition between the Lorentz-force-dominated and the
+Braginskii viscosity-dominated regimes in terms of a parameter $\sim \Omega
+\nub/B^2$ where $\nub$ is the viscous coefficient and $B$ the Alfv\'en speed.
+In the limit where the parameter is small and large respectively we recover the
+inviscid MRI and the magnetoviscous instability (MVI). We obtain asymptotic
+expressions for the approach to these limits, and find the Braginskii viscosity
+can magnify the effects of azimuthal hoop tension (the growth rate becomes
+complex) by over an order of magnitude. We discuss the relevance of our results
+to the local approximation, galaxies and other magnetized astrophysical
+plasmas. Our results should prove useful for benchmarking codes in global
+geometries.",1204.1948v1
+2012-10-25,Gravitational bremsstrahlung in ultra-planckian collisions,"A classical computation of gravitational bremsstrahlung in ultra-planckian
+collisions of massive point particles is presented in an arbitrary number d of
+toroidal or non-compact extra dimensions. Our method generalizes the
+post-linear formalism of General Relativity to the multidimensional case. The
+total emitted energy, as well as its angular and frequency distribution are
+discussed in detail. In terms of the gravitational radius r_S of the collision
+energy, the impact parameter b and the Lorentz factor in the CM frame, the
+leading order radiation efficiency in the Lab frame is shown to be of order
+(r_S/b)^{3(d+1)} gamma_{cm} for d=0, 1 and of order (r_S/b)^{3(d+1)}
+gamma_{cm}^{2d-3} for d>1, up to a known d-dependent coefficient and a ln
+gamma_{cm} factor for d=2, while the characteristic frequency of the radiation
+is gamma/b. The contribution of the low frequency part of the radiation (soft
+gravitons) to the total radiated energy is shown to be negligible for all
+values of d. The domain of validity of the classical result is discussed.
+Finally, it is shown that within the region of validity of our approach the
+efficiency can obtain unnatural values greater than one, which is interpreted
+to mean that the peripheral ultra-planckian collisions should be strongly
+radiation damped.",1210.6976v1
+2013-07-29,Shear shocks in fragile networks,"A minimal model for studying the mechanical properties of amorphous solids is
+a disordered network of point masses connected by unbreakable springs. At a
+critical value of its mean connectivity, such a network becomes fragile: it
+undergoes a rigidity transition signaled by a vanishing shear modulus and
+transverse sound speed. We investigate analytically and numerically the linear
+and non-linear visco-elastic response of these fragile solids by probing how
+shear fronts propagate through them. Our approach, that we tentatively label
+shear front rheology, provides an alternative route to standard oscillatory
+rheology. In the linear regime, we observe at late times a diffusive broadening
+of the fronts controlled by an effective shear viscosity that diverges at the
+critical point. No matter how small the microscopic coefficient of dissipation,
+strongly disordered networks behave as if they were over-damped because energy
+is irreversibly leaked into diverging non-affine fluctuations. Close to the
+transition, the regime of linear response becomes vanishingly small: the
+tiniest shear strains generate strongly non-linear shear shock waves
+qualitatively different from their compressional counterparts in granular
+media. The inherent non-linearities trigger an energy cascade from low to high
+frequency components that keep the network away from attaining the quasi-static
+limit. This mechanism, reminiscent of acoustic turbulence, causes a
+super-diffusive broadening of the shock width.",1307.7665v1
+2014-01-30,From the Samuelson Volatility Effect to a Samuelson Correlation Effect: Evidence from Crude Oil Calendar Spread Options,"We introduce a multi-factor stochastic volatility model based on the
+CIR/Heston stochastic volatility process. In order to capture the Samuelson
+effect displayed by commodity futures contracts, we add expiry-dependent
+exponential damping factors to their volatility coefficients. The pricing of
+single underlying European options on futures contracts is straightforward and
+can incorporate the volatility smile or skew observed in the market. We
+calculate the joint characteristic function of two futures contracts in the
+model in analytic form and use the one-dimensional Fourier inversion method of
+Caldana and Fusai (JBF 2013) to price calendar spread options. The model leads
+to stochastic correlation between the returns of two futures contracts. We
+illustrate the distribution of this correlation in an example. We then propose
+analytical expressions to obtain the copula and copula density directly from
+the joint characteristic function of a pair of futures. These expressions are
+convenient to analyze the term-structure of dependence between the two futures
+produced by the model. In an empirical application we calibrate the proposed
+model to volatility surfaces of vanilla options on WTI. In this application we
+provide evidence that the model is able to produce the desired stylized facts
+in terms of volatility and dependence. In a separate appendix, we give guidance
+for the implementation of the proposed model and the Fourier inversion results
+by means of one and two-dimensional FFT methods.",1401.7913v3
+2014-02-04,Complete Tidal Evolution of Pluto-Charon,"Both Pluto and its satellite Charon have rotation rates synchronous with
+their orbital mean motion. This is the theoretical end point of tidal evolution
+where transfer of angular momentum has ceased. Here we follow Pluto's tidal
+evolution from an initial state having the current total angular momentum of
+the system but with Charon in an eccentric orbit with semimajor axis $a \approx
+4R_P$ (where $R_P$ is the radius of Pluto), consistent with its impact origin.
+Two tidal models are used, where the tidal dissipation function $Q \propto$
+1/frequency and $Q=$ constant, where details of the evolution are strongly
+model dependent. The inclusion of the gravitational harmonic coefficient
+$C_{22}$ of both bodies in the analysis allows smooth, self consistent
+evolution to the dual synchronous state, whereas its omission frustrates
+successful evolution in some cases. The zonal harmonic $J_2$ can also be
+included, but does not cause a significant effect on the overall evolution. The
+ratio of dissipation in Charon to that in Pluto controls the behavior of the
+orbital eccentricity, where a judicious choice leads to a nearly constant
+eccentricity until the final approach to dual synchronous rotation. The tidal
+models are complete in the sense that every nuance of tidal evolution is
+realized while conserving total angular momentum - including temporary capture
+into spin-orbit resonances as Charon's spin decreases and damped librations
+about the same.",1402.0625v1
+2014-07-11,Chiral Hall Effect and Chiral Electric Waves,"We investigate the vector and axial currents induced by external
+electromagnetic fields and chemical potentials in chiral systems at finite
+temperature. Similar to the normal Hall effect, we find that an axial Hall
+current is generated in the presence of the electromagnetic fields along with
+an axial chemical potential, which may be dubbed as the ""chiral Hall
+effect""(CHE). The CHE is related to the interactions of chiral fermions and
+exists with the a nonzero axial chemical potential. We argue that the CHE could
+lead to nontrivial charge distributions at different rapidity in asymmetric
+heavy ion collisions. Moreover, we study the chiral electric waves(CEW) led by
+the fluctuations of the vector and axial chemical potentials along with the
+chiral electric separation effect(CESE), where a density wave propagates along
+the applied electric field. Combining with the normal/chiral Hall effects, the
+fluctuations of chemical potentials thus result in Hall density waves. The Hall
+density waves may survive even at zero chemical potentials and become
+non-dissipative. We further study the transport coefficients including the Hall
+conductivities, damping times, wave velocities, and diffusion constants of CEW
+in a strongly coupled plasma via the AdS/CFT correspondence.",1407.3168v3
+2014-09-01,Interface-resolved direct numerical simulation of the erosion of a sediment bed sheared by laminar channel flow,"A numerical method based upon the immersed boundary technique for the
+fluid-solid coupling and on a soft-sphere approach for solid-solid contact is
+used to perform direct numerical simulation of the flow-induced motion of a
+thick bed of spherical particles in a horizontal plane channel. The collision
+model features a normal force component with a spring and a damper, as well as
+a damping tangential component, limited by a Coulomb friction law. The standard
+test case of a single particle colliding perpendicularly with a horizontal wall
+in a viscous fluid is simulated over a broad range of Stokes numbers, yielding
+values of the effective restitution coefficient in close agreement with
+experimental data. The case of bedload particle transport by laminar channel
+flow is simulated for 24 different parameter values covering a broad range of
+the Shields number. Comparison of the present results with reference data from
+the experiment of Aussillous et al. (J. Fluid Mech. 2013) yields excellent
+agreement. It is confirmed that the particle flow rate varies with the third
+power of the Shields number once the known threshold value is exceeded. The
+present data suggests that the thickness of the mobile particle layer
+(normalized with the height of the clear fluid region) increases with the
+square of the normalized fluid flow rate.",1409.0339v1
+2014-10-28,Equations of a Moving Mirror and the Electromagnetic Field,"We consider a system composed of a mobile slab and the electromagnetic field.
+We assume that the slab is made of a material that has the following properties
+when it is at rest: it is linear, isotropic, non-magnetizable, and ohmic with
+zero free charge density. Using instantaneous Lorentz transformations, we
+deduce the set of self-consistent equations governing the dynamics of the
+system and we obtain approximate equations to first order in the velocity and
+the acceleration of the slab. As a consequence of the motion of the slab, the
+field must satisfy a wave equation with damping and slowly varying coefficients
+plus terms that are small when the time-scale of the evolution of the mirror is
+much smaller than that of the field. Also, the motion of the slab and its
+interaction with the field introduce two effects in the slab's equation of
+motion. The first one is a position- and time-dependent mass related to the
+$\textit{effective mass}$ taken in phenomenological treatments of this type of
+systems. The second one is a velocity-dependent force that can give rise to
+friction and that is related to the much sought $\textit{cooling}$ of
+mechanical objects.",1410.7609v2
+2014-12-17,Fluctuation-dissipation dynamics of cosmological scalar fields,"We show that dissipative effects have a significant impact on the evolution
+of cosmological scalar fields, leading to friction, entropy production and
+field fluctuations. We explicitly compute the dissipation coefficient for
+different scalar fields within the Standard Model and some of its most widely
+considered extensions, in different parametric regimes. We describe the generic
+consequences of fluctuation-dissipation dynamics in the post-inflationary
+universe, focusing in particular on friction and particle production, and
+analyze in detail two important effects. Firstly, we show that dissipative
+friction delays the process of spontaneous symmetry breaking and may even damp
+the the motion of a Higgs field sufficiently to induce a late period of warm
+inflation. Along with dissipative entropy production, this may parametrically
+dilute the abundance of dangerous thermal relics. Secondly, we show that
+dissipation can generate the observed baryon asymmetry without symmetry
+restoration, and we develop in detail a model of dissipative leptogenesis. We
+further show that this generically leads to characteristic baryon isocurvature
+perturbations that can be tested with CMB observations. This work provides a
+fundamental framework to go beyond the leading thermal equilibrium
+semi-classical approximation in addressing fundamental problems in modern
+cosmology.",1412.5489v2
+2014-12-22,H$_2$ Lyman and Werner band lines and their sensitivity for a variation of the proton-electron mass ratio in the gravitational potential of white dwarfs,"Recently an accurate analysis of absorption spectra of molecular hydrogen,
+observed with the Cosmic Origins Spectrograph aboard the Hubble Space
+Telescope, in the photosphere of white dwarf stars GD133 and GD29-38 was
+published in a Letter [Phys. Rev. Lett. 113, 123002 (2014)], yielding a
+constraint on a possible dependence of the proton-electron mass ratio on a
+gravitational field of strength 10,000 times that at the Earth's surface. In
+the present paper further details of that study are presented, in particular a
+re-evaluation of the spectrum of the $B^1\Sigma_u^+ - X^1\Sigma_g^+ (v',v'')$
+Lyman bands relevant for the prevailing temperatures (12,000 - 14,000 K) of the
+photospheres. An emphasis is on the calculation of so-called
+$K_i$-coefficients, that represent the sensitivity of each individual line to a
+possible change in the proton-electron mass ratio. Such calculations were
+performed by semi-empirical methods and by ab initio methods providing accurate
+and consistent values. A full listing is provided for the molecular physics
+data on the Lyman bands (wavelengths $\lambda_i$, line oscillator strengths
+$f_i$, radiative damping rates $\Gamma_i$, and sensitivity coefficients $K_i$)
+as required for the analyses of H$_2$-spectra in hot dwarf stars. A similar
+listing of the molecular physics parameters for the $C^1\Pi_u - X^1\Sigma_g^+
+(v',v'')$ Werner bands is provided for future use in the analysis of white
+dwarf spectra.",1412.6920v1
+2014-12-11,Modeling the Aerodynamic Lift Produced by Oscillating Airfoils at Low Reynolds Number,"For present study, setting Strouhal Number (St) as control parameter,
+numerical simulations for flow past oscillating NACA-0012 airfoil at 1,000
+Reynolds Numbers (Re) are performed. Temporal profiles of unsteady forces; lift
+and thrust, and their spectral analysis clearly indicate the solution to be a
+period-1 attractor for low Strouhal numbers. This study reveals that
+aerodynamic forces produced by plunging airfoil are independent of initial
+kinematic conditions of airfoil that proves the existence of limit cycle.
+Frequencies present in the oscillating lift force are composed of fundamental
+(fs), even and odd harmonics (3fs) at higher Strouhal numbers. Using numerical
+simulations, shedding frequencies (f_s) were observed to be nearly equal to the
+excitation frequencies in all the cases. Unsteady lift force generated due to
+the plunging airfoil is modeled by modified van der Pol oscillator. Using
+method of multiple scales and spectral analysis of steady-state CFD solutions,
+frequencies and damping terms in the van der Pol oscillator model are
+estimated. We prove the applicability of this model to all planar motions of
+airfoil; plunging, pitching and flapping. An important aspect of
+currently-proposed model is capturing the time-averaged value of aerodynamic
+lift coefficient.",1502.06431v1
+2015-03-09,Boundedness in a quasilinear fully parabolic Keller-Segel system of higher dimension with logistic source,"This paper deals with the higher dimension quasilinear parabolic-parabolic
+Keller-Segel system involving a source term of logistic type $
+u_t=\nabla\cdot(\phi(u)\nabla u)-\chi\nabla\cdot(u\nabla v)+g(u)$, $\tau
+v_t=\Delta v-v+u$ in $\Omega\times (0,T)$, subject to nonnegative initial data
+and homogeneous Neumann boundary condition, where $\Omega$ is smooth and
+bounded domain in $\mathbb{R}^n$, $n\ge 2$, $\phi$ and $g$ are smooth and
+positive functions satisfying $ks^p\le\phi$ when $s\ge s_0>1$, $g(s) \le as -
+\mu s^2$ for $s>0$ with $g(0)\ge0$ and constants $a\ge 0$, $\tau,\chi,\mu>0$.
+It was known that the model without the logistic source admits both bounded and
+unbounded solutions, identified via the critical exponent $\frac{2}{n}$. On the
+other hand, the model is just a critical case with the balance of logistic
+damping and aggregation effects, for which the property of solutions should be
+determined by the coefficients involved. In the present paper it is proved that
+there is $\theta_0>0$ such that the problem admits global bounded classical
+solutions, regardless of the size of initial data and diffusion whenever
+$\frac{\chi}{\mu}<\theta_0$. This shows the substantial effect of the logistic
+source to the behavior of solutions.",1503.02387v1
+2015-03-16,Effect of primordial magnetic fields on the ionization history,"Primordial magnetic fields (PMF) damp at scales smaller than the photon
+diffusion and free-streaming scale. This leads to heating of ordinary matter
+(electrons and baryons), which affects both the thermal and ionization history
+of our Universe. Here, we study the effect of heating due to ambipolar
+diffusion and decaying magnetic turbulence. We find that changes to the
+ionization history computed with recfast are significantly overestimated when
+compared with CosmoRec. The main physical reason for the difference is that the
+photoionization coefficient has to be evaluated using the radiation temperature
+rather than the matter temperature. A good agreement with CosmoRec is found
+after changing this aspect. Using Planck 2013 data and considering only the
+effect of PMF-induced heating, we find an upper limit on the r.m.s. magnetic
+field amplitude of B0 < 1.1 nG (95% c.l.) for a stochastic background of PMF
+with a nearly scale-invariant power spectrum. We also discuss uncertainties
+related to the approximations for the heating rates and differences with
+respect to previous studies. Our results are important for the derivation of
+constraints on the PMF power spectrum obtained from measurements of the cosmic
+microwave background anisotropies with full-mission Planck data. They may also
+change some of the calculations of PMF-induced effects on the primordial
+chemistry and 21cm signals.",1503.04827v1
+2015-11-18,Gravito-inertial waves in a differentially rotating spherical shell,"The gravito-inertial waves propagating over a shellular baroclinic flow
+inside a rotating spherical shell are analysed using the Boussinesq
+approximation. The wave properties are examined by computing paths of
+characteristics in the non-dissipative limit, and by solving the full
+dissipative eigenvalue problem using a high-resolution spectral method.
+Gravito-inertial waves are found to obey a mixed-type second-order operator and
+to be often focused around short-period attractors of characteristics or
+trapped in a wedge formed by turning surfaces and boundaries. We also find
+eigenmodes that show a weak dependence with respect to viscosity and heat
+diffusion just like truly regular modes. Some axisymmetric modes are found
+unstable and likely destabilized by baroclinic instabilities. Similarly, some
+non-axisymmetric modes that meet a critical layer (or corotation resonance) can
+turn unstable at sufficiently low diffusivities. In all cases, the instability
+is driven by the differential rotation. For many modes of the spectrum, neat
+power laws are found for the dependence of the damping rates with diffusion
+coefficients, but the theoretical explanation for the exponent values remains
+elusive in general. The eigenvalue spectrum turns out to be very rich and
+complex, which lets us suppose an even richer and more complex spectrum for
+rotating stars or planets that own a differential rotation driven by
+baroclinicity.",1511.05832v2
+2016-02-02,"Reflected brownian motion: selection, approximation and linearization","We construct a family of SDEs whose solutions select a reflected Brownian
+flow as well as a stochastic damped transport process (W\_t). The latter gives
+a representation for the solutions to the heat equation for differential
+1-forms with the absolute boundary conditions; it evolves pathwise by the Ricci
+curvature in the interior, by the shape operator on the boundary and driven by
+the boundary local time, and has its normal part erased on the boundary. On the
+half line this construction selects the Skorohod solution (and its derivative
+with respect to initial points), not the Tanaka solution. On the half space
+this agrees with the construction of N. Ikeda and S. Watanabe
+\cite{Ikeda-Watanabe} by Poisson point processes. This leads also to an
+approximation for the boundary local time in the topology of uniform
+convergence; not in the semi-martingale topology, indicating the difficulty for
+the convergence of solutions of a family of random ODE's, with nice
+coefficients, to the solution of an equation with jumps and driven by the local
+time. In addition, We note that (W\_t) is the weak derivative of a family of
+reflected Brownian motions with respect to the starting point.",1602.00897v4
+2016-02-06,Basic Properties of Conductivity and Normal Hall Effect in the Periodic Anderson Model,"Exact formulas of diagonal conductivity $\sigma_{xx}$ and Hall conductivity
+$\sigma_{xy}$ are derived from the Kubo formula in hybridized two-orbital
+systems with arbitrary band dispersions. On the basis of the theoretical
+framework for the Fermi liquid based on these formulas, the ground-state
+properties of the periodic Anderson model with electron correlation and weak
+impurity scattering are studied on the square lattice. It is shown that
+imbalance of the mass-renormalization factors in $\sigma_{xx}$ and
+$\sigma_{xy}$ causes remarkable increase in the valence-fluctuation regime as
+the f level increases while the cancellation of the renormalization factors
+causes slight increase in $\sigma_{xx}$ and $\sigma_{xy}$ in the Kondo regime.
+The Hall coefficient $R_{\rm H}$ shows almost constant behavior in both the
+regimes. Near half filling, $R_{\rm H}$ is expressed by the total hole density
+as $R_{\rm H}=1/(\bar{n}_{\rm hole}e)$ while $R_{\rm H}$ approaches zero near
+quarter filling, which reflects the curvature of the Fermi surface. These
+results hold as far as the damping rate for f electrons is less than about
+$10~\%$ of the renormalized hybridization gap. From these results we discuss
+pressure dependence of residual resistivity and normal Hall effect in Ce- and
+Yb-based heavy electron systems.",1602.02229v1
+2016-03-28,Kernelized Weighted SUSAN based Fuzzy C-Means Clustering for Noisy Image Segmentation,"The paper proposes a novel Kernelized image segmentation scheme for noisy
+images that utilizes the concept of Smallest Univalue Segment Assimilating
+Nucleus (SUSAN) and incorporates spatial constraints by computing circular
+colour map induced weights. Fuzzy damping coefficients are obtained for each
+nucleus or center pixel on the basis of the corresponding weighted SUSAN area
+values, the weights being equal to the inverse of the number of horizontal and
+vertical moves required to reach a neighborhood pixel from the center pixel.
+These weights are used to vary the contributions of the different nuclei in the
+Kernel based framework. The paper also presents an edge quality metric obtained
+by fuzzy decision based edge candidate selection and final computation of the
+blurriness of the edges after their selection. The inability of existing
+algorithms to preserve edge information and structural details in their
+segmented maps necessitates the computation of the edge quality factor (EQF)
+for all the competing algorithms. Qualitative and quantitative analysis have
+been rendered with respect to state-of-the-art algorithms and for images ridden
+with varying types of noises. Speckle noise ridden SAR images and Rician noise
+ridden Magnetic Resonance Images have also been considered for evaluating the
+effectiveness of the proposed algorithm in extracting important segmentation
+information.",1603.08564v1
+2016-06-11,Characterization of base roughness for granular chute flows,"Base roughness plays an important role to the dynamics of granular flows but
+is yet poorly understood due to the difficulty of its quantification. For a
+bumpy base made by spheres, at least two factors should be considered to
+characterize its geometric roughness, namely the size ratio of base- to
+flow-particles and the packing of base particles. In this paper, we propose a
+definition of base roughness, Ra, which is a function of both the size ratio
+and the packing arrangement of base particles. The function is generalized for
+random and regular packing of multi-layered spheres, where the range of
+possible values of Ra is studied, along with the optimal values to create
+maximum base roughness. The new definition is applied to granular flows down
+chute in both two- and three-dimensional configurations. It is proven to be a
+good indicator of slip condi- tion, and a transition occurs from slip to
+non-slip condition as Ra increases. Critical values of Ra are identified for
+the construction of a non-slip base. The effects of contact parameters on base
+velocity are studied, and it is shown that while the coefficient of friction is
+less influential, normal damping has more profound effect on base velocity at
+lower values of Ra. The application of present definition to other base
+geometries is also discussed.",1606.03554v1
+2016-06-22,Non-linear diffusion of cosmic rays escaping from supernova remnants - I. The effect of neutrals,"Supernova remnants are believed to be the main sources of galactic Cosmic
+Rays (CR). Within this framework, particles are accelerated at supernova
+remnant shocks and then released in the interstellar medium. The mechanism
+through which CRs are released and the way in which they propagate still remain
+open issues. The main difficulty is the high non-linearity of the problem: CRs
+themselves excite the magnetic turbulence that confines them close to their
+sources. We solve numerically the coupled differential equations describing the
+evolution in space and time of the escaping particles and of the waves
+generated through the CR streaming instability. The warm ionized and warm
+neutral phases of the interstellar medium are considered. These phases occupy
+the largest fraction of the disc volume, where most supernovae explode, and are
+characterised by the significant presence of neutral particles. The friction
+between those neutrals and ions results in a very effective wave damping
+mechanism. It is found that streaming instability affects the propagation of
+CRs even in the presence of ion-neutral friction. The diffusion coefficient can
+be suppressed by more than a factor of $\sim 2$ over a region of few tens of pc
+around the remnant. The suppression increases for smaller distances. The
+propagation of $\approx 10$ GeV particles is affected for several tens of
+kiloyears after escape, while $\approx 1$ TeV particles are affected for few
+kiloyears. This might have a great impact on the interpretation of gamma-ray
+observations of molecular clouds located in the vicinity of supernova remnants.",1606.06902v2
+2016-08-29,Hilbert space hypocoercivity for the Langevin dynamics revisited,"We provide a complete elaboration of the $L^2$-Hilbert space hypocoercivity
+theorem for the degenerate Langevin dynamics via studying the longtime behavior
+of the strongly continuous contraction semigroup solving the associated
+Kolmogorov (backward) equation as an abstract Cauchy problem. This
+hypocoercivity result is proven in previous works before by Dolbeault, Mouhot
+and Schmeiser in the corresponding dual Fokker-Planck framework, but without
+including domain issues of the appearing operators. In our elaboration, we
+include the domain issues and additionally compute the rate of convergence in
+dependence of the damping coefficient. Important statements for the complete
+elaboration are the m-dissipativity results for the Langevin operator
+established by Conrad and the first named author of this article as well as the
+essential selfadjointness results for generalized Schr\""{o}dinger operators by
+Wielens or Bogachev, Krylov and R\""{o}ckner. We emphasize that the chosen
+Kolmogorov approach is natural. Indeed, techniques from the theory of
+(generalized) Dirichlet forms imply a stochastic representation of the Langevin
+semigroup as the transition kernel of diffusion process which provides a
+martingale solution to the Langevin equation. Hence an interesting connection
+between the theory of hypocoercivity and the theory of (generalized) Dirichlet
+forms is established besides.",1608.07889v1
+2017-04-06,Evolution of a proto-neutron star with a nuclear many-body equation of state: Neutrino luminosity and gravitational wave frequencies,"In a core-collapse supernova, a huge amount of energy is released in the
+Kelvin-Helmholtz phase subsequent to the explosion, when the proto-neutron star
+cools and deleptonizes as it loses neutrinos. Most of this energy is emitted
+through neutrinos, but a fraction of it can be released through gravitational
+waves. We model the evolution of a proto-neutron star in the Kelvin-Helmholtz
+phase using a general relativistic numerical code, and a recently proposed
+finite temperature, many-body equation of state; from this we consistently
+compute the diffusion coefficients driving the evolution. To include the
+many-body equation of state, we develop a new fitting formula for the high
+density baryon free energy at finite temperature and intermediate proton
+fraction. We estimate the emitted neutrino signal, assessing its detectability
+by present terrestrial detectors, and we determine the frequencies and damping
+times of the quasi-normal modes which would characterize the gravitational wave
+signal emitted in this stage.",1704.01923v2
+2017-05-16,A Tube Dynamics Perspective Governing Stability Transitions: An Example Based on Snap-through Buckling,"The equilibrium configuration of an engineering structure, able to withstand
+a certain loading condition, is usually associated with a local minimum of the
+underlying potential energy. However, in the nonlinear context, there may be
+other equilibria present, and this brings with it the possibility of a
+transition to an alternative (remote) minimum. That is, given a sufficient
+disturbance, the structure might buckle, perhaps suddenly, to another shape.
+This paper considers the dynamic mechanisms under which such transitions
+(typically via saddle points) occur. A two-mode Hamiltonian is developed for a
+shallow arch/buckled beam. The resulting form of the potential energy---two
+stable wells connected by rank-1 saddle points---shows an analogy with
+resonance transitions in celestial mechanics or molecular reconfigurations in
+chemistry, whereas here the transition corresponds to switching between two
+stable structural configurations. Then, from Hamilton's equations, the
+analytical equilibria are determined and linearization of the equations of
+motion about the saddle is obtained. After computing the eigenvalues and
+eigenvectors of the coefficient matrix associated with the linearization, a
+symplectic transformation is given which puts the Hamiltonian into normal form
+and simplifies the equations, allowing us to use the conceptual framework known
+as tube dynamics. The flow in the equilibrium region of phase space as well as
+the invariant manifold tubes in position space are discussed. Also, we account
+for the addition of damping in the tube dynamics framework, which leads to a
+richer set of behaviors in transition dynamics than previously explored.",1705.05903v2
+2018-02-13,Acoustic Disturbances in Galaxy Clusters,"Galaxy cluster cores are pervaded by hot gas which radiates at far too high a
+rate to maintain any semblance of a steady state; this is referred to as the
+cooling flow problem. Of the many heating mechanisms that have been proposed to
+balance radiative cooling, one of the most attractive is dissipation of
+acoustic waves generated by Active Galactic Nuclei (AGN). Fabian (2005) showed
+that if the waves are nearly adiabatic, wave damping due to heat conduction and
+viscosity must be well below standard Coulomb rates in order to allow the waves
+to propagate throughout the core. Because of the importance of this result, we
+have revisited wave dissipation under galaxy cluster conditions in a way that
+accounts for the self limiting nature of dissipation by electron thermal
+conduction, allows the electron and ion temperature perturbations in the waves
+to evolve separately, and estimates kinetic effects by comparing to a
+semi-collisionless theory. While these effects considerably enlarge the toolkit
+for analyzing observations of wavelike structures and developing a quantitative
+theory for wave heating, the drastic reduction of transport coefficients
+proposed in Fabian (2005) remains the most viable path to acoustic wave heating
+of galaxy cluster cores.",1802.04808v2
+2018-04-23,Dissipation-Based Continuation Method for Multiphase Flow in Heterogeneous Porous Media,"In reservoir simulation, solution of the coupled systems of nonlinear
+algebraic equations that are associated with fully-implicit (backward Euler)
+discretization is challenging. Having a robust and efficient nonlinear solver
+is necessary in order for reservoir simulation to serve as the primary tool for
+managing the recovery processes of large-scale reservoirs. Here, we develop a
+continuation method based on the use of a dissipation operator. We focus on
+nonlinear two-phase flow and transport in heterogeneous formations in the
+presence of viscous, gravitational, and capillary forces. The homotopy is
+constructed by adding numerical dissipation to the coupled discrete
+conservation equations. A continuation parameter is introduced to control the
+amount of dissipation. Numerical evidence of multi-dimensional models and
+detailed analysis of single-cell problems are used to explain how the
+dissipation operator improves the nonlinear convergence of the coupled system
+of equations. An adaptive strategy to determine the dissipation coefficient is
+proposed. The dissipation level is computed locally for each cell interface. We
+demonstrate the efficiency of the dissipation-based continuation (DBC)
+nonlinear solver using several examples, including 1D scalar transport and 2D
+heterogeneous problems with fully-coupled flow and transport. The DBC solver
+has better convergence properties compared with the standard damped-Newton
+solvers used in reservoir simulation.",1804.08538v2
+2018-05-08,A fast adhesive discrete element method for random packings of fine particles,"Introducing a reduced particle stiffness in discrete element method (DEM)
+allows for bigger time steps and therefore fewer total iterations in a
+simulation. Although this approach works well for dry non-adhesive particles,
+it has been shown that for fine particles with adhesion, system behaviors are
+drastically sensitive to the particle stiffness. Besides, a simple and
+applicable principle to set the parameters in adhesive DEM is also lacking. To
+solve these two problems, we first propose a fast DEM based on scaling laws to
+reduce particle Young's modulus, surface energy and to modify rolling and
+sliding resistances simultaneously in the framework of Johnson-Kendall-Roberts
+(JKR)-based contact theory. A novel inversion method is then presented to help
+users to quickly determine the damping coefficient, particle stiffness and
+surface energy to reproduce a prescribed experimental result. After validating
+this inversion method, we apply the fast adhesive DEM to packing problems of
+microparticles. Measures of packing fraction, averaged coordination number and
+distributions of local packing fraction and contact number of each particle are
+in good agreement with results simulated using original value of particle
+properties. The new method should be helpful to accelerate DEM simulations for
+systems associated with aggregates or agglomerates.",1805.03025v2
+2019-01-13,Stochastic resonance and bifurcation of order parameter in a coupled system of underdamped Duffing oscillators,"The long-term mean-field dynamics of coupled underdamped Duffing oscillators
+driven by an external periodic signal with Gaussian noise is investigated. A
+Boltzmann-type H-theorem is proved for the associated nonlinear Fokker-Planck
+equation to ensure that the system can always be relaxed to one of the
+stationary states as time is long enough. Based on a general framework of the
+linear response theory, the linear dynamical susceptibility of the system order
+parameter is explicitly deduced. With the spectral amplification factor as a
+quantifying index, calculation by the method of moments discloses that both
+mono-peak and double-peak resonance might appear, and that noise can greatly
+signify the peak of the resonance curve of the coupled underdamped system as
+compared with a single-element bistable system. Then, with the input signals
+taken from laboratory experiments, further observations show that the
+mean-field coupled stochastic resonance system can amplify the periodic input
+signal. Also, it reveals that for some driving frequencies, the optimal
+stochastic resonance parameter and the critical bifurcation parameter have a
+close relationship. Moreover, it is found that the damping coefficient can also
+give rise to nontrivial non-monotonic behaviors of the resonance curve, and the
+resultant resonant peak attains its maximal height if the noise intensity or
+the coupling strength takes the critical value. The new findings reveal the
+role of the order parameter in a coupled system of chaotic oscillators.",1901.03955v2
+2019-03-19,Conservative Discontinuous Galerkin Schemes for Nonlinear Fokker-Planck Collision Operators,"We present a novel discontinuous Galerkin algorithm for the solution of a
+class of Fokker-Planck collision operators. These operators arise in many
+fields of physics, and our particular application is for kinetic plasma
+simulations. In particular, we focus on an operator often known as the
+`Lenard-Bernstein,' or `Dougherty,' operator. Several novel algorithmic
+innovations are reported. The concept of weak-equality is introduced and used
+to define weak-operators to compute primitive moments needed in the updates.
+Weak-equality is also used to determine a reconstruction procedure that allows
+an efficient and accurate discretization of the diffusion term. We show that
+when two integration by parts are used to construct the discrete weak-form, and
+finite velocity-space extents are accounted for, a scheme that conserves
+density, momentum and energy exactly is obtained. One novel feature is that the
+requirements of momentum and energy conservation lead to unique formulas to
+compute primitive moments. Careful definition of discretized moments also
+ensure that energy is conserved in the piecewise linear case, even though the
+$v^2$ term is not included in the basis-set used in the discretization. A
+series of benchmark problems are presented and show that the scheme conserves
+momentum and energy to machine precision. Empirical evidence also indicates
+that entropy is a non-decreasing function. The collision terms are combined
+with the Vlasov equation to study collisional Landau damping and plasma heating
+via magnetic pumping. We conclude with an outline of future work, in particular
+with some indications of how the algorithms presented here can be extended to
+use the Rosenbluth potentials to compute the drag and diffusion coefficients.",1903.08062v1
+2019-03-20,Limits of flexural wave absorption by open lossy resonators: reflection and transmission problems,"The limits of flexural wave absorption by open lossy resonators are
+analytically and numerically reported in this work for both the reflection and
+transmission problems. An experimental validation for the reflection problem is
+presented. The reflection and transmission of flexural waves in 1D resonant
+thin beams are analyzed by means of the transfer matrix method. The hypotheses,
+on which the analytical model relies, are validated by experimental results.
+The open lossy resonator, consisting of a finite length beam thinner than the
+main beam, presents both energy leakage due to the aperture of the resonators
+to the main beam and inherent losses due to the viscoelastic damping. Wave
+absorption is found to be limited by the balance between the energy leakage and
+the inherent losses of the open lossy resonator. The perfect compensation of
+these two elements is known as the critical coupling condition and can be
+easily tuned by the geometry of the resonator. On the one hand, the scattering
+in the reflection problem is represented by the reflection coefficient. A
+single symmetry of the resonance is used to obtain the critical coupling
+condition. Therefore the perfect absorption can be obtained in this case. On
+the other hand, the transmission problem is represented by two eigenvalues of
+the scattering matrix, representing the symmetric and anti-symmetric parts of
+the full scattering problem. In the geometry analyzed in this work, only one
+kind of symmetry can be critically coupled, and therefore, the maximal
+absorption in the transmission problem is limited to 0.5. The results shown in
+this work pave the way to the design of resonators for efficient flexural wave
+absorption.",1903.08522v1
+2019-04-18,Emergence of hydrodynamical behavior in expanding quark-gluon plasmas,"We use a set of simple angular moments to solve the Boltzmann equation in the
+relaxation time approximation for a boost invariant longitudinally expanding
+gluonic plasma. The transition from the free streaming regime at early time to
+the hydrodynamic regime at late time is well captured by the first two-moments,
+corresponding to the monopole and quadrupole components of the momentum
+distribution, or equivalently to the energy density and the difference between
+the longitudinal and the transverse pressures. We relate this property to the
+existence of fixed points in the infinite hierarchy of equations satisfied by
+the moments. These fixed points are already present in the two-moment
+truncations and are only moderately affected by the coupling to higher moments.
+Collisions contribute to a damping of all the non trivial moments. At late
+time, when the hydrodynamic regime is entered, only the monopole and quadrupole
+moments are significant and remain strongly coupled, the decay of the
+quadrupole moment being delayed by the expansion, causing in turn a delay in
+the full isotropization of the system. The two-moment truncation contains
+second order viscous hydrodynamics, in its various variants, and third order
+hydrodynamics, together with explicit values of the relevant transport
+coefficients, can be easily obtained from the three-moment truncation.",1904.08677v1
+2019-04-29,A nonlinear subgrid-scale model for large-eddy simulations of rotating turbulent flows,"Rotating turbulent flows form a challenging test case for large-eddy
+simulation (LES). We, therefore, propose and validate a new subgrid-scale (SGS)
+model for such flows. The proposed SGS model consists of a dissipative eddy
+viscosity term as well as a nondissipative term that is nonlinear in the
+rate-of-strain and rate-of-rotation tensors. The two corresponding model
+coefficients are a function of the vortex stretching magnitude. Therefore, the
+model is consistent with many physical and mathematical properties of the
+Navier-Stokes equations and turbulent stresses, and is easy to implement. We
+determine the two model constants using a nondynamic procedure that takes into
+account the interaction between the model terms. Using detailed direct
+numerical simulations (DNSs) and LESs of rotating decaying turbulence and
+spanwise-rotating plane-channel flow, we reveal that the two model terms
+respectively account for dissipation and backscatter of energy, and that the
+nonlinear term improves predictions of the Reynolds stress anisotropy near
+solid walls. We also show that the new SGS model provides good predictions of
+rotating decaying turbulence and leads to outstanding predictions of
+spanwise-rotating plane-channel flow over a large range of rotation rates for
+both fine and coarse grid resolutions. Moreover, the new nonlinear model
+performs as well as the dynamic Smagorinsky and scaled anisotropic
+minimum-dissipation models in LESs of rotating decaying turbulence and
+outperforms these models in LESs of spanwise-rotating plane-channel flow,
+without requiring (dynamic) adaptation or near-wall damping of the model
+constants.",1904.12748v1
+2019-04-29,Dynamics of scalar fields in an expanding/contracting cosmos at finite temperature,"This paper extends the study of the quantum dissipative effects of a
+cosmological scalar field by taking into account the cosmic expansion and
+contraction. Cheung, Drewes, Kang and Kim calculated the effective action and
+quantum dissipative effects of a cosmological scalar field. The analytic
+expressions for the effective potential and damping coefficient were presented
+using a simple scalar model with quartic interaction. Their work was done using
+Minkowski-space propagators in loop diagrams. In this work we incorporate the
+Hubble expansion and contraction of the comic background, and focus on the
+thermal dynamics of a scalar field in a regime where the effective potential
+changes slowly. We let the Hubble parameter, $H$, attain a small but non-zero
+value and carry out calculations to first order in $H$. If we set $H=0$ all
+results match those obtained previously in flat spacetime [1]. Interestingly we
+have to integrate over the resonances, which in turn leads to an amplification
+of the effects of a non-zero $H$. This is an intriguing phenomenon which cannot
+be uncovered in flat spacetime. The implications on particle creations in the
+early universe will be studied in a forthcoming work.",1904.12941v2
+2019-05-09,Global Robustness vs. Local Vulnerabilities in Complex Synchronous Networks,"In complex network-coupled dynamical systems, two questions of central
+importance are how to identify the most vulnerable components and how to devise
+a network making the overall system more robust to external perturbations. To
+address these two questions, we investigate the response of complex networks of
+coupled oscillators to local perturbations. We quantify the magnitude of the
+resulting excursion away from the unperturbed synchronous state through
+quadratic performance measures in the angle or frequency deviations. We find
+that the most fragile oscillators in a given network are identified by
+centralities constructed from network resistance distances. Further defining
+the global robustness of the system from the average response over ensembles of
+homogeneously distributed perturbations, we find that it is given by a family
+of topological indices known as generalized Kirchhoff indices. Both resistance
+centralities and Kirchhoff indices are obtained from a spectral decomposition
+of the stability matrix of the unperturbed dynamics and can be expressed in
+terms of resistance distances. We investigate the properties of these
+topological indices in small-world and regular networks. In the case of
+oscillators with homogeneous inertia and damping coefficients, we find that
+inertia only has small effects on robustness of coupled oscillators. Numerical
+results illustrate the validity of the theory.",1905.03582v1
+2019-05-20,Out of time ordered effective dynamics of a quartic oscillator,"We study the dynamics of a quantum Brownian particle weakly coupled to a
+thermal bath. Working in the Schwinger-Keldysh formalism, we develop an
+effective action of the particle up to quartic terms. We demonstrate that this
+quartic effective theory is dual to a stochastic dynamics governed by a
+non-linear Langevin equation. The Schwinger-Keldysh effective theory, or the
+equivalent non-linear Langevin dynamics, is insufficient to determine the out
+of time order correlators (OTOCs) of the particle. To overcome this limitation,
+we construct an extended effective action in a generalised Schwinger-Keldysh
+framework. We determine the additional quartic couplings in this OTO effective
+action and show their dependence on the bath's 4-point OTOCs. We analyse the
+constraints imposed on the OTO effective theory by microscopic reversibility
+and thermality of the bath. We show that these constraints lead to a
+generalised fluctuation-dissipation relation between the non-Gaussianity in the
+distribution of the thermal noise experienced by the particle and the thermal
+jitter in its damping coefficient. The quartic effective theory developed in
+this work provides extension of several results previously obtained for the
+cubic OTO dynamics of a Brownian particle.",1905.08307v6
+2019-06-11,Instability of flux flow and production of vortex-antivortex pairs by current-driven Josephson vortices in layered superconductors,"We report numerical simulations of the nonlinear dynamics of Josephson
+vortices driven by strong dc currents in layered superconductors. Dynamic
+equations for interlayer phase differences in a stack of coupled
+superconducting layers were solved to calculate a drag coefficient $\eta(J)$ of
+the vortex as a function of the perpendicular dc current density $J$. It is
+shown that Cherenkov radiation produced by a moving vortex causes significant
+radiation drag increasing $\eta(v)$ at high vortex velocities $v$ and striking
+instabilities of driven Josephson vortices moving faster than a terminal
+velocity $v_c$. The steady-state flux flow breaks down at $v>v_c$ as the vortex
+starts producing a cascade of expanding vortex-antivortex pairs evolving into
+either planar macrovortex structures or branching flux patterns propagating
+both along and across the layers. The pair production triggered by a rapidly
+moving vortex is most pronounced in a stack of underdamped planar junctions
+where it can occur at $J>J_s$ well below the interlayer Josephson critical
+current density. Both $v_c$ and $J_s$ were calculated as functions of the
+quasiparticle damping parameter, and the dc magnetic field applied parallel to
+the layers. The effects of vortex interaction on the Cherenkov instability of
+moving vortex chains and lattices in annular stacks of Josephson junctions were
+considered. It is shown that a vortex driven by a current density $J>J_s$ in a
+multilayer of finite length excites self-sustained large-amplitude standing
+waves of magnetic flux, resulting in temporal oscillations of the total
+magnetic moment. We evaluated a contribution of this effect to the power $W$
+radiated by the sample and showed that $W$ increases strongly as the number of
+layers increases.",1906.04783v1
+2020-01-22,Probing XY phase transitions in a Josephson junction array with tunable frustration,"The seminal theoretical works of Berezinskii, Kosterlitz, and Thouless
+presented a new paradigm for phase transitions in condensed matter that are
+driven by topological excitations. These transitions have been extensively
+studied in the context of two-dimensional XY models -- coupled compasses -- and
+have generated interest in the context of quantum simulation. Here, we use a
+circuit quantum-electrodynamics architecture to study the critical behavior of
+engineered XY models through their dynamical response. In particular, we
+examine not only the unfrustrated case but also the fully-frustrated case which
+leads to enhanced degeneracy associated with the spin rotational [U$(1)$] and
+discrete chiral ($Z_2$) symmetries. The nature of the transition in the
+frustrated case has posed a challenge for theoretical studies while direct
+experimental probes remain elusive. Here we identify the transition
+temperatures for both the unfrustrated and fully-frustrated XY models by
+probing a Josephson junction array close to equilibrium using weak microwave
+excitations and measuring the temperature dependence of the effective damping
+obtained from the complex reflection coefficient. We argue that our probing
+technique is primarily sensitive to the dynamics of the U$(1)$ part.",2001.07877v2
+2020-01-30,Electrical spectroscopy of forward volume spin waves in perpendicularly magnetized materials,"We study the potential of all-electrical inductive techniques for the
+spectroscopy of propagating forward volume spin waves. We develop a
+one-dimensional model to account for the electrical signature of spin-wave
+reflection and transmission between inductive antennas and validate it with
+experiments on a perpendicularly magnetized Co/Ni multilayer. We describe the
+influence of the antenna geometry and antenna-to-antenna separation, as well as
+that of the material parameters on the lineshape of the inductive signals. For
+a finite damping, the broadband character of the antenna emission in the wave
+vector space imposes to take into account the growing decoherence of the
+magnetization waves upon their spatial propagation. The transmission signal can
+be viewed as resulting from two contributions: a first one from propagating
+spin-waves leading to an oscillatory phase of the broadband transmission
+coefficient, and another one originating from the distant induction of
+ferromagnetic resonance because of the long-range stray fields of realistic
+antennas. Depending on the relative importance of these two contributions, the
+decay of the transmitted signal with the propagation distance may not be
+exponential and the oscillatory character of the spin-wave phase upon
+propagation may be hidden. Our model and its experimental validation allow to
+define geometrical and material specifications to be met to enable the use of
+forward volume spin waves as efficient information carriers.",2001.11483v1
+2020-02-27,Dipole polarizability of time-varying particles,"Invariance under time translation (or stationarity) is probably one of the
+most important assumptions made when investigating electromagnetic phenomena.
+Breaking this assumption is expected to open up novel possibilities and result
+in exceeding conventional limitations. However, to explore the field of
+time-varying electromagnetic structures, we primarily need to contemplate the
+fundamental principles and concepts from a nonstationarity perspective. Here,
+we revisit one of those key concepts: The polarizability of a small particle,
+assuming that its properties vary in time. We describe the creation of induced
+dipole moment by external fields in a nonstationary, causal way, and introduce
+a complex-valued function, called temporal complex polarizability, for
+elucidating a nonstationary Hertzian dipole under time-harmonic illumination.
+This approach can be extended to any subwavelength particle exhibiting electric
+response. In addition, we also study the classical model of the polarizability
+of an oscillating electron using the equation of motion whose damping
+coefficient and natural frequency are changing in time. Next, we theoretically
+derive the effective permittivity corresponding to time-varying media
+(comprising free or bound electrons, or dipolar meta-atoms) and explicitly show
+the differences with the conventional macroscopic Drude-Lorentz model. This
+paper will hopefully pave the road towards better understanding of
+nonstationary scattering from small particles and homogenization of
+time-varying materials, metamaterials, and metasurfaces.",2002.12297v3
+2020-02-25,The Casimir densities for a sphere in the Milne universe,"The influence of a spherical boundary on the vacuum fluctuations of a massive
+scalar field is investigated in background of $(D+1)$-dimensional Milne
+universe, assuming that the field obeys Robin boundary condition on the sphere.
+The normalized mode functions are derived for the regions inside and outside
+the sphere and different vacuum states are discussed. For the conformal vacuum,
+the Hadamard function is decomposed into boundary-free and sphere-induced
+contributions and an integral representation is obtained for the latter in both
+the interior and exterior regions. As important local characteristics of the
+vacuum state the vacuum expectation values (VEVs) of the field squared and of
+the energy-momentum tensor are investigated. It is shown that the vacuum
+energy-momentum tensor has an off-diagonal component that corresponds to the
+energy flux along the radial direction. Depending on the coefficient in Robin
+boundary condition the sphere-induced contribution to the vacuum energy and the
+energy flux can be either positive or negative. At late stages of the expansion
+and for a massive field the decay of the sphere-induced VEVs, as functions of
+time, is damping oscillatory. The geometry under consideration is conformally
+related to that for a static spacetime with negative constant curvature space
+and the sphere-induced contributions in the corresponding VEVs are compared.",2003.05372v2
+2020-04-15,On the cavity evolution and the Rayleigh--Plesset equation in superfluid helium,"On the basis of the two-fluid hydrodynamics, an analogue of the famous
+Rayleigh-Plesse equation for the dynamics of a spherical bubble in superfluid
+helium is obtained. The mass flow velocity $v$ and the velocity of the normal
+component $v_{n}$ were chosen as independent variables. Due to the two-fluid
+nature of HeII, the cross terms in the evolution equation for the boundary
+position $\ R(t)$ appeared, which were absent in classical Rayleigh-Plesset
+equation in ordinary fluids. One of them renormilizes the coefficient in front
+of $(dR/dt)^{2}$. Another additional term formally coinciding with the viscous
+term, describes the attenuation of the boundary oscillations. This
+""extra-damping"" term, greatly exceeding the usual viscous term, leads to a
+significant difference in the dynamics of cavity compared to HeI. In
+particular, this results in the interesting effect of abnormal suppression of
+oscillations of the vapor--liquid boundary observed in many works. There is
+also an additional term proportional to the squared velocity of the normal
+component, which is independent of the derivative $dR/dt$, and can be included
+in the pressure drop. Its physical meaning is that it describes a ""Bernoulli""
+-like pressure created by the flow of a normal component. The obtained result
+declares that some results on the dynamics of the cavity in superfluid helium
+should be reviewed",2004.06893v1
+2020-05-30,Spiral defect chaos in Rayleigh-Bénard convection: Asymptotic and numerical studies of azimuthal flows induced by rotating spirals,"Rotating spiral patterns in Rayleigh-B\'enard convection are known to induce
+azimuthal flows, which raises the question of how different neighboring spirals
+interact with each other in spiral chaos, and the role of hydrodynamics in this
+regime. Far from the core, we show that spiral rotations lead to an azimuthal
+body force that is irrotational and of magnitude proportional to the
+topological index of the spiral and its angular frequency. The force, although
+irrotational, cannot be included in the pressure field as it would lead to a
+nonphysical, multivalued pressure. We calculate the asymptotic dependence of
+the resulting flow, and show that it leads to a logarithmic dependence of the
+azimuthal velocity on distance r away from the spiral core in the limit of
+negligible damping coefficient. This solution dampens to approximately $1/r$
+when accounting for no-slip boundary conditions for the convection cell's
+plate. This flow component can provide additional hydrodynamic interactions
+among spirals including those observed in spiral defect chaos. We show that the
+analytic prediction for the azimuthal velocity agrees with numerical results
+obtained from both two-dimensional generalized Swift-Hohenberg and
+three-dimensional Boussinesq models, and find that the velocity field is
+affected by the size and charges of neighboring spirals. Numerically, we
+identify a correlation between the appearance of spiral defect chaos and the
+balancing between the mean-flow advection and the diffusive dynamics related to
+roll unwinding.",2006.00147v1
+2020-06-16,Learning Rates as a Function of Batch Size: A Random Matrix Theory Approach to Neural Network Training,"We study the effect of mini-batching on the loss landscape of deep neural
+networks using spiked, field-dependent random matrix theory. We demonstrate
+that the magnitude of the extremal values of the batch Hessian are larger than
+those of the empirical Hessian. We also derive similar results for the
+Generalised Gauss-Newton matrix approximation of the Hessian. As a consequence
+of our theorems we derive an analytical expressions for the maximal learning
+rates as a function of batch size, informing practical training regimens for
+both stochastic gradient descent (linear scaling) and adaptive algorithms, such
+as Adam (square root scaling), for smooth, non-convex deep neural networks.
+Whilst the linear scaling for stochastic gradient descent has been derived
+under more restrictive conditions, which we generalise, the square root scaling
+rule for adaptive optimisers is, to our knowledge, completely novel. %For
+stochastic second-order methods and adaptive methods, we derive that the
+minimal damping coefficient is proportional to the ratio of the learning rate
+to batch size. We validate our claims on the VGG/WideResNet architectures on
+the CIFAR-$100$ and ImageNet datasets. Based on our investigations of the
+sub-sampled Hessian we develop a stochastic Lanczos quadrature based on the fly
+learning rate and momentum learner, which avoids the need for expensive
+multiple evaluations for these key hyper-parameters and shows good preliminary
+results on the Pre-Residual Architecure for CIFAR-$100$.",2006.09092v6
+2020-07-20,Hydrodynamic and thermal characteristics of a freely-vibrating circular cylinder in mixed convection flow,"The hydrodynamic and thermal characteristics of a freely-vibrating circular
+cylinder in mixed convection flow are numerically investigated at low Reynolds
+numbers. The numerical investigations are conducted for a range of parameters,
+Ur = [2.0, 10], Pr = [0.7, 10] and Ri = [0.5, 2.0]. Whereas the Reynolds
+number, the mass ratio and the damping ratio are fixed. A secondary VIV lock-in
+region is found in the cases of high Richardson number Ri=2.0 for high reduced
+velocity values, in which the buoyancy-driven flow is non-trivial. A wide VIV
+lock-in region is formed with tremendous energy transfer between fluid and
+structure, which is extremely meaningful for hydropower harvesting. The
+influences of Prandtl and Richardson numbers on the hydrodynamics, structural
+dynamics and heat transfer are discussed in detail. The temperature contours
+are concentrated around cylinder for the cases of high Prandtl number, which
+are associated with high mean Nusselt values. The influence on heat transfer
+efficiency over the cylinder's surface is quantified via the calculation of
+mean Nusselt number and its fluctuation for different circumstances. The energy
+transfer coefficient is employed to quantify the energy transfer between fluid
+and structure in mixed convection flow. The phase angle difference between the
+transverse displacement of cylinder and the lift force is used to support the
+discussions of energy transfer. A stabilized finite element formulation in
+Arbitrary Lagrangian-Eulerian description is derived. The structural dynamics
+and vortex-induced vibration are documented for various environments, e.g.,
+different reduced velocity, Prandtl numbers and Richardson numbers. The
+influence of structural dynamics on the heat transfer efficiency over a heated
+cylinder is recorded and discussed as well. The obtained numerical results
+match well with literature and the established empirical formula.",2007.10091v2
+2020-07-29,Delayed Rebounds in the Two-Ball Bounce Problem,"In the classroom demonstration of a tennis ball dropped on top of a
+basketball, the surprisingly high bounce of the tennis ball is typically
+explained using momentum conservation for elastic collisions, with the
+basketball-floor collision treated as independent from the collision between
+the two balls. This textbook explanation is extended to inelastic collisions by
+including a coefficient of restitution. This independent contact model (ICM),
+as reviewed in this paper, is accurate for a wide variety of cases, even when
+the collisions are not truly independent. However, it is easy to explore
+situations that are not explained by the ICM, such as swapping the tennis ball
+for a ping-pong ball. In this paper, we study the conditions that lead to a
+""delayed rebound effect,"" a small first bounce followed by a higher second
+bounce, using techniques accessible to an undergraduate student. The dynamical
+model is based on the familiar solution of the damped harmonic oscillator. We
+focus on making the equations of motion dimensionless for numerical simulation,
+and reducing the number of parameters and initial conditions to emphasize
+universal behavior. The delayed rebound effect is found for a range of
+parameters, most commonly in cases where the first bounce is lower than the ICM
+prediction.",2007.15005v2
+2020-08-08,Axial Gravitational Waves in Bianchi I Universe,"In this paper, we have studied the propagation of axial gravitational waves
+in Bianchi I universe using the Regge-Wheeler gauge. In this gauge, there are
+only two non-zero components of $ h_{\mu\nu} $ in the case of axial waves:
+$h_0(t,r)$ and $h_1(t,r)$. The field equations in absence of matter have been
+derived both for the unperturbed as well as axially perturbed metric. These
+field equations are solved simultaneously by assuming the expansion scalar
+$\Theta$ to be proportional to the shear scalar $\sigma$ (so that $a= b^n$,
+where $a$, $b$ are the metric coefficients and $n$ is an arbitrary constant),
+and the wave equation for the perturbation parameter $h_0(t,r)$ have been
+derived. We used the method of separation of variables to solve for this
+parameter, and have subsequently determined $h_1(t,r)$. We then discuss a few
+special cases in order to interpret the results. We find that the anisotropy of
+the background spacetime is responsible for the damping of the gravitational
+waves as they propagate through this spacetime. The perturbations depend on the
+values of the angular momentum $l$. The field equations in the presence of
+matter reveal that the axially perturbed spacetime leads to perturbations only
+in the azimuthal velocity of the fluid leaving the matter field undisturbed.",2008.04780v2
+2020-11-13,Hopf Bifurcation for General 1D Semilinear Wave Equations with Delay,"We consider boundary value problems for 1D autonomous damped and delayed
+semilinear wave equations of the type $$ \partial^2_t u(t,x)-
+a(x,\lambda)^2\partial_x^2u(t,x)=
+b(x,\lambda,u(t,x),u(t-\tau,x),\partial_tu(t,x),\partial_xu(t,x)), \; x \in
+(0,1) $$ with smooth coefficient functions $a$ and $b$ such that
+$a(x,\lambda)>0$ and $b(x,\lambda,0,0,0,0) = 0$ for all $x$ and $\lambda$. We
+state conditions ensuring Hopf bifurcation, i.e., existence, local uniqueness
+(up to time shifts), regularity (with respect to $t$ and $x$) and smooth
+dependence (on $\tau$ and $\lambda$) of small non-stationary time-periodic
+solutions, which bifurcate from the stationary solution $u=0$, and we derive a
+formula which determines the bifurcation direction with respect to the
+bifurcation parameter $\tau$.
+  To this end, we transform the wave equation into a system of partial integral
+equations by means of integration along characteristics, and then we apply a
+Lyapunov-Schmidt procedure and a generalized implicit function theorem to this
+system. The main technical difficulties, which have to be managed, are typical
+for hyperbolic PDEs (with or without delay): small divisors and the ""loss of
+derivatives"" property.
+  We do not use any properties of the corresponding initial-boundary value
+problem. In particular, our results are true also for negative delays $\tau$.",2011.06824v1
+2020-12-01,"Digital Light Processing in a Hybrid Atomic Force Microscope: In situ, Nanoscale Characterization of the Printing Process","Stereolithography (SLA) and digital light processing (DLP) are powerful
+additive manufacturing techniques that address a wide range of applications
+including regenerative medicine, prototyping, and manufacturing. Unfortunately,
+these printing processes introduce micrometer-scale anisotropic inhomogeneities
+due to the resin absorptivity, diffusivity, reaction kinetics, and swelling
+during the requisite photoexposure. Previously, it has not been possible to
+characterize high-resolution mechanical heterogeneity as it develops during the
+printing process. By combining DLP 3D printing with atomic force microscopy in
+a hybrid instrument, heterogeneity of a single, in situ printed voxel is
+characterized. Here, we describe the instrument and demonstrate three
+modalities for characterizing voxels during and after printing. Sensing
+Modality I maps the mechanical properties of just-printed, resin-immersed
+voxels, providing the framework to study the relationships between voxel sizes,
+print exposure parameters, and voxel-voxel interactions. Modality II captures
+the nanometric, in situ working curve and is the first demonstration of in situ
+cure depth measurement. Modality III dynamically senses local rheological
+changes in the resin by monitoring the viscoelastic damping coefficient of the
+resin during patterning. Overall, this instrument equips researchers with a
+tool to develop rich insight into resin development, process optimization, and
+fundamental printing limits.",2012.00496v1
+2021-02-23,Cosmic Ray Transport in the Ionized and Neutral ISM: MHD-PIC Simulations and Effective Fluid Treatments,"Cosmic rays (CRs) have critical impacts in the multiphase interstellar medium
+(ISM), driving dynamical motions in low-density plasma and modifying the
+ionization state, temperature, and chemical composition of higher-density
+atomic and molecular gas. We present a study of CR propagation between the
+ionized ISM and a neutral cloud. Using one-dimensional magnetohydrodynamic
+particle-in-cell simulations which include ion-neutral drag to damp
+Alfv$\acute{\text{e}}$n waves in the cloud, we self-consistently evolve the
+kinetic physics of CRs and fluid dynamics of the multiphase gas. By introducing
+the cloud in our periodic domain, our simulations break translational symmetry
+and allow the emergence of spatial structure in the CR distribution function. A
+negative spatial gradient forms across the fully-ionized ISM region while a
+positive gradient forms across the neutral cloud. We connect our results with
+CR hydrodynamics formulations by computing the wave-particle scattering rates
+as predicted by quasilinear, fluid, and Fokker-Planck theory. For momenta where
+the mean free path is short relative to the box size, we find excellent
+agreement among all scattering rates. By exploring different cloud sizes and
+ion-neutral collision rates, we show that our results are robust. Our work
+provides a first-principles verification of CR hydrodynamics when particles
+stream down their pressure gradient, and opens a pathway toward comprehensive
+calibrations of transport coefficients from self-generated
+Alfv$\acute{\text{e}}$n wave scattering with CRs.",2102.11877v1
+2021-03-10,Quasi-solid state microscopic dynamics in equilibrium classical liquids: Self-consisnent relaxation theory,"In the framework of the concept of time correlation functions, we develop a
+self-consistent relaxation theory of the transverse collective particle
+dynamics in liquids. The theory agrees with well-known results in both the
+short-wave (free particle dynamics) and the long-wave (hydrodynamic) limits. We
+obtain a general expression for the spectral density~$C_T(k,\omega)$ of
+transverse particle current realized in the range of wave numbers $k$. In
+domain of microscopic spatial scales comparable to action scale of effective
+forces of interparticle interaction, the theory reproduces a transition from a
+regime with typical equilibrium liquid dynamics to a regime with collective
+particle dynamics where properties similar to solid-state properties appear:
+effective shear stiffness and transverse (shear) acoustic waves. In the
+framework of the corresponding approximations, we obtain expressions for the
+spectral density of transverse particle current for all characteristic regimes
+in equilibrium collective dynamics. We obtain expressions for dispersion law
+for transverse (shear) acoustic waves and also relations for the kinematic
+shear viscosity $\nu$, the transverse speed of sound $v^{(T)}$, and the
+corresponding sound damping coefficient $\Gamma^{(T)}$. We compare the
+theoretical results with the results of atomic dynamics simulations of liquid
+lithium near the melting point.",2103.06241v1
+2021-04-01,Brownian motion under intermittent harmonic potentials,"We study the effects of an intermittent harmonic potential of strength $\mu =
+\mu_0 \nu$ -- that switches on and off stochastically at a constant rate
+$\gamma$, on an overdamped Brownian particle with damping coefficient $\nu$.
+This can be thought of as a realistic model for realisation of stochastic
+resetting. We show that this dynamics admits a stationary solution in all
+parameter regimes and compute the full time dependent variance for the position
+distribution and find the characteristic relaxation time. We find the exact
+non-equilibrium stationary state distributions in the limits -- (i)
+$\gamma\ll\mu_0 $ which shows a non-trivial distribution, in addition as
+$\mu_0\to\infty$, we get back the result for resetting with refractory period;
+(ii) $\gamma\gg\mu_0$ where the particle relaxes to a Boltzmann distribution of
+an Ornstein-Uhlenbeck process with half the strength of the original potential
+and (iii) intermediate $\gamma=2n\mu_0$ for $n=1, 2$. The mean first passage
+time (MFPT) to find a target exhibits an optimisation with the switching rate,
+however unlike instantaneous resetting the MFPT does not diverge but reaches a
+stationary value at large rates. MFPT also shows similar behavior with respect
+to the potential strength. Our results can be verified in experiments on
+colloids using optical tweezers.",2104.00609v2
+2021-04-29,Resonant Chains of Exoplanets: Libration Centers for Three-body Angles,"Resonant planetary systems contain at least one planet pair with orbital
+periods librating at a near-integer ratio (2/1, 3/2, 4/3, etc.) and are a
+natural outcome of standard planetary formation theories. Systems with multiple
+adjacent resonant pairs are known as resonant chains and can exhibit three-body
+resonances -- characterized by a critical three-body angle. Here we study
+three-body angles as a diagnostic of resonant chains through tidally-damped
+N-body integrations. For each combination of the 2:1, 3:2, 4:3, and 5:4 mean
+motion resonances (the most common resonances in the known resonant chains), we
+characterize the three-body angle equilibria for several mass schemes,
+migration timescales, and initial separations. We find that under our
+formulation of the three-body angle, which does not reduce coefficients, 180
+deg is the preferred libration center, and libration centers shifted away from
+180 deg are associated with non-adjacent resonances. We then relate these
+angles to observables, by applying our general results to two transiting
+systems: Kepler-60 and Kepler-223. For these systems, we compare N-body models
+of the three-body angle to the zeroth order in e approximation accessible via
+transit phases, used in previous publications. In both cases, we find the
+three-body angle during the Kepler observing window is not necessarily
+indicative of the long-term oscillations and stress the role of dynamical
+models in investigating three-body angles. We anticipate our results will
+provide a useful diagnostic in the analysis of resonant chains.",2104.14665v1
+2021-04-30,Complete modeling of hydrodynamic bearings with a boundary parameterization approach,"The present work aims to revisit the simplifications made in the
+Navier-Stokes equations for the flow between two cylinders with a small
+thickness of lubricating oil film. Through a dimensionless analysis, the terms
+of these equations are mapped and ordered by importance for the hydrodynamic
+bearing application. An effective parameterization of the geometry is proposed,
+enabling a more detailed description of the problem and its adaptation to other
+contexts. At the end, an elliptical partial differential equation is reached
+and solved by the centered finite difference method, whose solution is the
+pressure field between the cylinders. To illustrate the effectiveness of the
+proposed approach, the model is applied to hydrodynamic bearings, where the
+pressure field and some parameters resulting from it, such as stiffness and
+damping coefficients, are computed. Based on the facilities offered by the
+parameterization of the geometry, two different configurations are presented:
+(1) elliptical and (2) worn bearings. Their responses are evaluated and a
+comparative analysis is performed. The modeling exposed in this text, as well
+as all its simulations were developed to integrate Ross-Rotordynamics, an open
+library in Python, available on the GitHub platform.",2105.00118v3
+2021-07-27,Performance-based optimal distribution of viscous dampers in structure using hysteretic energy compatible endurance time excitations,"Performance-based optimization of energy dissipation devices in structures
+necessitates massive and repetitive dynamic analyses. In the endurance time
+method known as a rather fast dynamic analysis procedure, structures are
+subjected to intensifying dynamic excitations and their response at multiple
+intensity levels is estimated by a minimal number of analyses. So, this method
+significantly reduces computational endeavors. In this paper, the endurance
+time method is employed to determine the optimal placement of viscous dampers
+in a weak structure to achieve the desired performance at various hazard
+levels, simultaneously. The viscous damper is one of the energy dissipation
+systems which can dissipate a large amount of seismic input energy to the
+structure. To this end, hysteretic energy compatible endurance time excitation
+functions are used and the validity of the results is investigated by comparing
+them with the results obtained from a suite of ground motions. To optimize the
+placement of the dampers, the genetic algorithm is used. The damping
+coefficients of the dampers are considered as design variables in the
+optimization procedure and determined in such a way that the sum of them has a
+minimum value. The behavior of the weak structure before and after
+rehabilitation is also investigated using endurance time and nonlinear time
+history analysis procedures in different hazard levels.",2107.12983v1
+2021-08-18,Velocity auto correlation function of a confined Brownian particle,"Motivated by the simple models of molecular motor obeying a linear
+force-velocity relation, we have studied the stochastic dynamics of a Brownian
+particle in the presence of a linear velocity dependent force,
+$f_s(1-\frac{v}{v_0})$ where $f_{s}$ is a constant. The position and velocity
+auto correlation functions in different situations of the dynamics are
+calculated exactly. We observed that the velocity auto correlation function
+shows an exponentially decaying behaviour with time and saturates to a constant
+value in the time asymptotic limit, for a fixed $f_s$. It attains saturation
+faster with increase in the $f_{s}$ value. When the particle is confined in a
+harmonic well, the spectral density exhibits a symmetric behaviour and the
+corresponding velocity auto correlation function shows a damped oscillatory
+behaviour before decaying to zero in the long time limit. With viscous
+coefficient, a non-systematic variation of the velocity auto correlation
+function is observed. Further, in the presence of a sinusoidal driving force,
+the correlation in velocities increases with increase in the amplitude of
+driving in the transient regime. For the particle confined in a harmonic well,
+the correlation corresponding to the shift relative to the average position is
+basically the thermal contribution to the total position correlation. Moreover,
+in the athermal regime, the total correlation is entirely due to the velocity
+dependent force.",2108.07922v1
+2021-10-08,Relationship between low-discrepancy sequence and static solution to multi-bodies problem,"The main interest of this paper is to study the relationship between the
+low-discrepancy sequence and the static solution to the multi-bodies problem in
+high-dimensional space. An assumption that the static solution to the
+multi-bodies problem is a low-discrepancy sequence is proposed. Considering the
+static solution to the multi-bodies problem corresponds to the minimum
+potential energy principle, we further assume that the distribution of the
+bodies is the most uniform when the potential energy is the smallest. To verify
+the proposed assumptions, a dynamical evolutionary model (DEM) based on the
+minimum potential energy is established to find out the static solution. The
+central difference algorithm is adopted to solve the DEM and an evolutionary
+iterative scheme is developed. The selection of the mass and the damping
+coefficient to ensure the convergence of the evolutionary iteration is
+discussed in detail. Based on the DEM, the relationship between the potential
+energy and the discrepancy during the evolutionary iteration process is
+studied. It is found that there is a significant positive correlation between
+them, which confirms the proposed assumptions. We also combine the DEM with the
+restarting technique to generate a series of low-discrepancy sequences. These
+sequences are unbiased and perform better than other low-discrepancy sequences
+in terms of the discrepancy, the potential energy, integrating eight test
+functions and computing the statistical moments for two practical stochastic
+problems. Numerical examples also show that the DEM can not only generate
+uniformly distributed sequences in cubes, but also in non-cubes.",2110.03918v1
+2021-12-08,Resolving Hall and dissipative viscosity ambiguities via boundary effects,"We examine the physical implications of the viscous redundancy of
+two-dimensional anisotropic fluids, where different components of the viscosity
+tensor lead to identical effects in the bulk of a system [Rao and Bradlyn,
+Phys. Rev. X $\textbf{10}$, 021005 (2020)]. We first re-introduce the
+redundancy, show how it reflects a lack of knowledge of microscopic information
+of a system, and give microscopic examples. Next, we show that fluid flow in
+systems with a boundary can distinguish between otherwise redundant viscosity
+coefficients. In particular, we show how the dispersion and damping of
+gravity-dominated surface waves can be used to resolve the redundancies between
+both dissipative and Hall viscosities, and discuss how these results apply to
+recent experiments in chiral active fluids with nonvanishing Hall viscosity.
+Our results highlight the importance of divergenceless, magnetization-like
+contributions to the stress (which we dub ``contact terms''). Finally, we apply
+our results to the hydrodynamics of quantum Hall fluids, and show that the
+extra contribution to the action that renders the bulk Wen-Zee action gauge
+invariant in systems with a boundary can be reinterpreted in terms of the bulk
+viscous redundancy.",2112.04545v2
+2021-12-25,Transport and modeling of subgrid-scale turbulent kinetic energy in channel flows,"To develop a more convenient subgrid-scale (SGS) model that performs well
+even in coarse grid cases, we investigate the transport and modeling of SGS
+turbulent kinetic energy (hereafter SGS energy) in turbulent channel flows
+based on the stabilized mixed model (SMM). In this paper, we try to increase
+the convenience of the SMM by replacing the modeled transport equation for the
+SGS energy with an algebraic model. The SMM quantitatively adequately predicts
+the total turbulent kinetic energy of the direct numerical simulation (DNS)
+even in coarse grid cases. For both the filtered DNS (fDNS) and large-eddy
+simulation (LES), the statistically averaged production term balances with the
+dissipation in the region away from the wall in the SGS energy transport
+equation. In contrast, we reveal that the correlation coefficient between the
+production and dissipation terms is high for the modeled transport equation in
+LES, whereas that for the fDNS is low. Based on the high correlation or local
+equilibrium between the production and dissipation observed in the LES, we
+demonstrate the reduction of the SMM into a zero-equation SMM (ZE-SMM). We
+construct a new damping function based on the grid-scale Kolmogorov length to
+reproduce the near-wall behavior of the algebraic model for the SGS energy. The
+ZE-SMM provides quantitatively the same performance as the original SMM that
+employs the SGS energy transport model. This result suggests that the local
+equilibrium model for the SGS energy provides the equivalent performance as the
+transport model in wall-bounded turbulent flows even in coarse grid cases.",2112.13200v3
+2022-01-08,Local Gyrokinetic Collisional Theory of the Ion-Temperature Gradient Mode,"We present a study of the linear properties of ion temperature gradient (ITG)
+modes with collisions modelled by the linearized gyrokinetic (GK) Coulomb
+collision operator (Frei et al. 2021) in the local limit. The study is based on
+a Hermite-Laguerre polynomial expansion of the perturbed ion distribution
+function applied to the linearized GK Boltzmann equation, yielding a hierarchy
+of coupled equations for the expansion coefficients, referred to as
+gyro-moments. We explore analytically the collisionless and high-collisional
+limits of the gyro-moment hierarchy. Parameter scans revealing the dependence
+of the ITG growth rate on the collisionality are reported, showing strong
+damping at small scales as the collisionality increases. These properties are
+compared with the predictions based on the Sugama, the momentum-conserving
+pitch-angle scattering, the Hirshman- Sigmar-Clarke, and the Daugherty
+collision operators. The importance of finite Larmor radius (FLR) terms in the
+collision operators is pointed out by the appearance of a short wavelength (SW)
+ITG branch when collisional FLR terms are neglected, this branch being
+completely suppressed by collisional FLR effects. We demonstrate that energy
+diffusion is important at high collisionality and small scale lengths and that,
+among the collision operators considered in this work, the GK Sugama collision
+operator yields, in general, the smallest deviation on the ITG growth rate
+compared to the GK Coulomb collision operator. Convergence studies of the
+gyro-moment method are reported.",2201.02860v2
+2022-02-11,Cosmic-ray generated bubbles around their sources,"Cosmic rays are thought to escape their sources streaming along the local
+magnetic field lines. We show that this phenomenon generally leads to the
+excitation of both resonant and non-resonant streaming instabilities. The
+self-generated magnetic fluctuations induce particle diffusion in extended
+regions around the source, so that cosmic rays build up a large pressure
+gradient. By means of two-dimensional (2D) and three-dimensional (3D) hybrid
+particle-in-cell simulations, we show that such a pressure gradient excavates a
+cavity around the source and leads to the formation of a cosmic-ray dominated
+bubble, inside which diffusivity is strongly suppressed. Based on the trends
+extracted from self-consistent simulations, we estimate that, in the absence of
+severe damping of the self-generated magnetic fields, the bubble should keep
+expanding until pressure balance with the surrounding medium is reached,
+corresponding to a radius of $\sim 10-50$ pc. The implications of the formation
+of these regions of low diffusivity for sources of Galactic cosmic rays are
+discussed. Special care is devoted to estimating the self-generated diffusion
+coefficient and the grammage that cosmic rays might accumulate in the bubbles
+before moving into the interstellar medium. Based on the results of 3D
+simulations, general considerations on the morphology of the $\gamma$-ray and
+synchrotron emission from these extended regions also are outlined.",2202.05814v1
+2022-02-22,Criterion of Bari basis property for $2 \times 2$ Dirac-type operators with strictly regular boundary conditions,"The paper is concerned with the Bari basis property of a boundary value
+problem associated in $L^2([0,1]; \mathbb{C}^2)$ with the following $2 \times
+2$ Dirac-type equation for $y = {\rm col}(y_1, y_2)$: $$L_U(Q) y =-i B^{-1} y'
++ Q(x) y = \lambda y , \quad B = \begin{pmatrix} b_1 & 0 \\ 0 & b_2
+\end{pmatrix}, \quad b_1 < 0 < b_2, $$ with a potential matrix $Q \in
+L^2([0,1]; \mathbb{C}^{2 \times 2})$ and subject to the strictly regular
+boundary conditions $Uy :=\{U_1, U_2\}y=0$. If $b_2 = -b_1 =1$ this equation is
+equivalent to one dimensional Dirac equation. We show that the system of root
+vectors $\{f_n\}_{n \in \mathbb{Z}}$ of the operator $L_U(Q)$ forms a Bari
+basis in $L^2([0,1]; \mathbb{C}^2)$ if and only if the unperturbed operator
+$L_U(0)$ is self-adjoint. We also give explicit conditions for this in terms of
+coefficients in the boundary conditions. The Bari basis criterion is a
+consequence of our more general result: Let $Q \in L^p([0,1]; \mathbb{C}^{2
+\times 2})$, $p \in [1,2]$, boundary conditions be strictly regular, and let
+$\{g_n\}_{n \in \mathbb{Z}}$ be the sequence biorthogonal to the system of root
+vectors $\{f_n\}_{n \in \mathbb{Z}}$ of the operator $L_U(Q)$. Then $$ \{\|f_n
+- g_n\|_2\}_{n \in \mathbb{Z}} \in (\ell^p(\mathbb{Z}))^*
+\quad\Leftrightarrow\quad L_U(0) = L_U(0)^*. $$ These abstract results are
+applied to non-canonical initial-boundary value problem for a damped string
+equation.",2202.11148v1
+2022-03-22,Hydromagnetic waves in an expanding universe -- cosmological MHD code tests using analytic solutions,"We describe how analytic solutions for linear hydromagnetic waves can be used
+for testing cosmological magnetohydrodynamic (MHD) codes. We start from the
+comoving MHD equations and derive analytic solutions for the amplitude
+evolution of linear hydromagnetic waves in a matter-dominated, flat
+Einstein-de-Sitter (EdS) universe. The waves considered are comoving, linearly
+polarized Alfv\'en waves and comoving, magnetosonic (fast) waves modified by
+self-gravity. The solution for compressible waves is found for a general
+adiabatic index and we consider the limits of hydrodynamics without
+self-gravity in addition to the full solution. In addition to these analytic
+solutions, the linearized equations are solved numerically for a $\Lambda$CDM
+cosmology. We use the analytic and numeric solutions to compare with results
+obtained using the cosmological MHD code AREPO and find good agreement when
+using a sufficient number of grid points. We interpret the numerical damping
+clearly evident in simulations with few grid points by further deriving the
+Alfv\'en wave solution including physical Navier-Stokes viscosity. A comparison
+between Alfv\'en wave simulations and theory reveals that the dissipation can
+be described by a numerical viscosity coefficient $\eta_\mathrm{num} \propto
+a^{-5/2}$ where $a$ is the scale factor. We envision that our examples could be
+useful when developing a new cosmological MHD code or for regression testing of
+existing codes.",2203.11887v2
+2022-03-22,Cosmic-Ray Transport in Varying Galactic Environments,"We study the propagation of mildly-relativistic cosmic rays (CRs) in
+multiphase interstellar medium environments with conditions typical of nearby
+disk galaxies. We employ the techniques developed in Armillotta+21 to
+post-process three high-resolution TIGRESS magnetohydrodynamic simulations
+modeling local patches of star-forming galactic disks. Together, the three
+simulations cover a wide range of gas surface density, gravitational potential,
+and star formation rate (SFR). Our prescription for CR propagation includes the
+effects of advection by the background gas, streaming along the magnetic field
+at the local ion Alfv\'en speed, and diffusion relative to the Alfv\'en waves,
+with the diffusion coefficient set by the balance between streaming-driven
+Alfv\'en wave excitation and damping mediated by local gas properties. We find
+that the combined transport processes are more effective in environments with
+higher SFR. These environments are characterized by higher-velocity hot
+outflows (created by clustered supernovae) that rapidly advect CRs away from
+the galactic plane. As a consequence, the ratio of midplane CR pressure to
+midplane gas pressures decreases with increasing SFR. We also use the
+post-processed simulations to make predictions regarding potential dynamical
+impacts of CRs. The relatively flat CR pressure profiles near the midplane
+argue that they would not provide significant support against gravity for most
+of the ISM mass. However, the CR pressure gradients are larger than the other
+pressure gradients in the extra-planar region (|z|>0.5 kpc), suggesting that
+CRs may affect the dynamics of galactic fountains and/or winds. The degree of
+this impact is expected to increase in environments with lower SFR.",2203.11949v1
+2022-05-23,Universal mechanical response of metallic glasses during strain-rate-dependent uniaxial compression,"Experimental data on the compressive strength $\sigma_{\rm max}$ versus
+strain rate ${\dot \varepsilon}_{\rm eng}$ for metallic glasses undergoing
+uniaxial compression shows significantly different behavior for different
+alloys. For some metallic glasses, $\sigma_{\rm max}$ decreases with increasing
+${\dot \varepsilon}_{\rm eng}$, for others, $\sigma_{\rm max}$ increases with
+increasing ${\dot \varepsilon}_{\rm eng}$, and for others $\sigma_{\rm max}$
+versus ${\dot \varepsilon}_{\rm eng}$ is nonmonotonic. Using numerical
+simulations of metallic glasses undergoing uniaxial compression at nonzero
+strain rate and temperature, we show that they obey a universal relation for
+the compressive strength versus temperature, which determines their mechanical
+response. At low ${\dot \varepsilon}_{\rm eng}$, increasing strain rate leads
+to increases in temperature and decreases in $\sigma^*_{\rm max}$, whereas at
+high ${\dot \varepsilon}_{\rm eng}$, increasing strain rate leads to decreases
+in temperature and increases in $\sigma^*_{\rm max}$. This non-monotonic
+behavior of $\sigma^*_{\rm max}$ versus temperature causes the nonmonotonic
+behavior of $\sigma^*_{\rm max}$ versus ${\dot \varepsilon}_{\rm eng}$.
+Variations in the internal dissipation change the characteristic strain rate at
+which the nonmonotonic behavior occurs. These results are general for a wide
+range of metallic glasses with different atomic interactions, damping
+coefficients, and chemical compositions.",2205.11340v1
+2022-05-29,Negative cavity photon spectral function in an optomechanical system with two parametrically-driven mechanical modes,"We propose an experimentally feasible optomechanical scheme to realize a
+negative cavity photon spectral function (CPSF) which is equivalent to a
+negative absorption. The system under consideration is an optomechanical system
+consisting of two mechanical (phononic) modes which are linearly coupled to a
+common cavity mode via the radiation pressure while parametrically driven
+through the coherent time-modulation of their spring coefficients. Using the
+equations of motion for the cavity retarded Green's function obtained in the
+framework of the generalized linear response theory, we show that in the
+red-detuned and weak-coupling regimes a frequency-dependent effective cavity
+damping rate (ECDR) corresponding to a negative CPSF can be realized by
+controlling the cooperativities and modulation parameters while the system
+still remains in the stable regime. Nevertheless, such a negativity which acts
+as an optomechanical gain never occurs in a standard (an unmodulated bare)
+cavity optomechanical system. Besides, we find that the presence of two
+modulated mechanical degrees of freedom provides more controllability over the
+magnitude and bandwidth of the negativity of CPSF, in comparison to the setup
+with a single modulated mechanical oscillator. Interestingly, the introduced
+negativity may open a new platform to realize an extraordinary (modified)
+optomechanically induced transparency (in which the input signal is amplified
+in the output) leading to a perfect tunable optomechanical filter with
+switchable bandwidth which can be used as an optical transistor.",2205.15314v3
+2022-06-27,Diffusion in the Presence of Correlated Returns in a Two-dimensional Energy Landscape and non-Monotonic Friction Dependence: Examination of Simulation Results by a Random Walk Model,"Diffusion in a multidimensional energy surface with minima and barriers is a
+problem of importance in statistical mechanics and also has wide applications,
+such as protein folding. To understand it in such a system, we carry out theory
+and simulations of a tagged particle moving on a two-dimensional periodic
+potential energy surface, both in the presence and absence of noise. Langevin
+dynamics simulations at multiple temperatures are carried out to obtain the
+diffusion coefficient of a solute particle. Friction is varied from zero to
+large values. Diffusive motion emerges in the limit of long times, even in the
+absence of noise, although the trajectory is found to remain correlated over a
+long time. This correlation is manifested in correlated returns to the starting
+minima following a scattering by surrounding maxima. Noise destroys this
+correlation, induces chaos, and increases diffusion at small friction.
+Diffusion thus exhibits a non-monotonic friction dependence at the intermediate
+value of the damping, ultimately converging to our theoretically predicted
+value. The latter is obtained by using the well-established relation between
+diffusion and random walk. An excellent agreement is obtained between theory
+and simulations in the high friction limit, but not so in the intermediate
+regime. The rate of escape from one cell to another is obtained from the
+multidimensional rate theory of Langer. We find that enhanced dimensionality
+plays an important role. In order to quantify the effects of noise on the
+potential-imposed coherence on the trajectories, we calculate the Lyapunov
+exponent. At small friction values, the Lyapunov exponent mimics the friction
+dependence of the rate.",2206.13565v1
+2022-07-14,The Damped Wave Equation with Acoustic Boundary Conditions and Non-locally Reacting Surfaces,"The aim of the paper is to study the problem $$u_{tt}+du_t-c^2\Delta u=0
+\qquad \text{in $\mathbb{R}\times\Omega$,}$$ $$\mu v_{tt}- \text{div}_\Gamma
+(\sigma \nabla_\Gamma v)+\delta v_t+\kappa v+\rho u_t =0\qquad \text{on
+$\mathbb{R}\times \Gamma_1$,}$$ $$v_t =\partial_\nu u\qquad \text{on
+$\mathbb{R}\times \Gamma_1$,}$$ $$\partial_\nu u=0 \text{on $\mathbb{R}\times
+\Gamma_0$,}$$ $$u(0,x)=u_0(x),\quad u_t(0,x)=u_1(x)\quad \text{in $\Omega$,}$$
+$$v(0,x)=v_0(x),\quad v_t(0,x)=v_1(x) \quad \text{on $\Gamma_1$,}$$ where
+$\Omega$ is a open domain of $\mathbb{R}^N$ with uniformly $C^r$ boundary
+($N\ge 2$, $r\ge 1$), $\Gamma=\partial\Omega$, $(\Gamma_0,\Gamma_1)$ is a
+relatively open partition of $\Gamma$ with $\Gamma_0$ (but not $\Gamma_1$)
+possibly empty. Here $\text{div}_\Gamma$ and $\nabla_\Gamma$ denote the
+Riemannian divergence and gradient operators on $\Gamma$, $\nu$ is the outward
+normal to $\Omega$, the coefficients $\mu,\sigma,\delta, \kappa, \rho$ are
+suitably regular functions on $\Gamma_1$ with $\rho,\sigma$ and $\mu$ uniformly
+positive, $d$ is a suitably regular function in $\Omega$ and $c$ is a positive
+constant.
+  In this paper we first study well-posedness in the natural energy space and
+give regularity results. Hence we study asymptotic stability for solutions when
+$\Omega$ is bounded, $\Gamma_1$ is connected, $r=2$, $\rho$ is constant and
+$\kappa,\delta,d\ge 0$.",2207.07047v2
+2022-08-01,Stochastic Galerkin particle methods for kinetic equations of plasmas with uncertainties,"The study of uncertainty propagation is of fundamental importance in plasma
+physics simulations. To this end, in the present work we propose a novel
+stochastic Galerkin (sG) particle {method} for collisional kinetic models of
+plasmas under the effect of uncertainties. This class of methods is based on a
+generalized polynomial chaos (gPC) expansion of the particles' position and
+velocity. In details, we introduce a stochastic particle approximation for the
+Vlasov-Poisson system with a BGK term describing plasma collisions. A careful
+reformulation of such dynamics is needed to perform the sG projection and to
+obtain the corresponding system for the gPC coefficients. We show that the sG
+particle method preserves the main physical properties of the problem, such as
+conservations and positivity of the solution, while achieving spectral accuracy
+for smooth solutions in the random space. Furthermore, in the fluid limit the
+sG particle solver is designed to possess the asymptotic-preserving property
+necessary to obtain a sG particle scheme for the limiting Euler-Poisson system,
+thus avoiding the loss of hyperbolicity typical of conventional sG methods
+based on finite differences or finite volumes. We tested the schemes
+considering the classical Landau damping problem in the presence of both small
+and large initial uncertain perturbations, the two stream instability and the
+Sod shock tube problems under uncertainties. The results show that the proposed
+method is able to capture the correct behavior of the system in all test cases,
+even when the relaxation time scale is very small.",2208.00692v2
+2022-08-02,Diagrammatic perturbation theory for Stochastic nonlinear oscillators,"We consider the stochastically driven one dimensional nonlinear oscillator
+$\ddot{x}+2\Gamma\dot{x}+\omega^2_0 x+\lambda x^3 = f(t)$ where f(t) is a
+Gaussian noise which, for the bulk of the work, is delta correlated (white
+noise). We construct the linear response function in frequency space in a
+systematic Feynman diagram-based perturbation theory. As in other areas of
+physics, this expansion is characterized by the number of loops in the diagram.
+This allows us to show that the damping coefficient acquires a correction at
+$O(\lambda^2)$ which is the two loop order. More importantly, it leads to the
+numerically small but conceptually interesting finding that the response is a
+function of the frequency at which a stochastic system is probed. The method is
+easily generalizable to different kinds of nonlinearity and replacing the
+nonlinear term in the above equation by $\mu x^2$ , we can discuss the issue of
+noise driven escape from a potential well. If we add a periodic forcing to the
+cubic nonlinearity situation, then we find that the response function can have
+a contribution jointly proportional to the strength of the noise and the
+amplitude of the periodic drive. To treat the stochastic Kapitza problem in
+perturbation theory we find that it is necessary to have a coloured noise.",2208.01349v2
+2022-08-09,Pulsar radio emission mechanism II. On the origin of relativistic Langmuir solitons in pulsar plasma,"Observations suggest that coherent radio emission from pulsars is excited in
+a dense pulsar plasma by curvature radiation from charge bunches. Numerous
+studies propose that these charge bunches are relativistic charge solitons
+which are solutions of the non-linear Schr\""{o}dinger equation (NLSE) with a
+group velocity dispersion ($G$), cubic-nonlinearity($q$) and non-linear Landau
+damping ($s$). The formation of stable solitons crucially depends on the
+parameters $G, q$ and $s$ and the particle distribution function. In this work,
+we use realistic pulsar plasma parameters obtained from observational
+constraints to explore the parameter space of NLSE for two representative
+distribution functions (DF) of particles' momenta: Lorentzian (long-tailed) and
+Gaussian (short-tailed). The choice of DF critically affects the value of
+$|s/q|$, which, in turn, determines whether solitons can form. Numerical
+simulations show that well-formed solitons are obtained only for small values
+of $|s/q| \lesssim 0.1$ while for moderate and higher values of $|s/q| \gtrsim
+0.5$ soliton formation is suppressed. Small values for $|s/q| \sim 0.1$ are
+readily obtained for long-tailed DF for a wide range of plasma temperatures. On
+the other hand, short-tailed DF provides these values only for some narrow
+range of plasma parameters. Thus, the presence of a prominent high-energy tail
+in the particle DF favours soliton formation for a wide range of plasma
+parameters. Besides pair plasma, we also include an iron ion component and find
+that they make a negligible contribution in either modifying the NLSE
+coefficients or contributing to charge separation.",2208.04894v1
+2022-08-24,Analysis of point-contact models of the bounce of a hard spinning ball on a compliant frictional surface,"Inspired by the turf-ball interaction in golf, this paper seeks to understand
+the bounce of a ball that can be modelled as a rigid sphere and the surface as
+supplying an elasto-plastic contact force in addition to Coulomb friction. A
+general formulation is proposed that models the finite time interval of bounce
+from touch-down to lift-off. Key to the analysis is understanding transitions
+between slip and roll during the bounce. Starting from the rigid-body limit
+with a an energetic or Poisson coefficient of restitution, it is shown that
+slip reversal during the contact phase cannot be captured in this case, which
+result generalises to the case of pure normal compliance. Yet, the introduction
+of linear tangential stiffness and damping, does enable slip reversal. This
+result is extended to general weakly nonlinear normal and tangential
+compliance. An analysis using Filippov theory of piecewise-smooth systems leads
+to an argument in a natural limit that lift-off while rolling is non-generic
+and that almost all trajectories that lift off, do so under slip conditions.
+Moreover, there is a codimension-one surface in the space of incoming velocity
+and spin which divides balls that lift off with backspin from those that lift
+off with topspin. The results are compared with recent experimental
+measurements on golf ball bounce and the theory is shown to capture the main
+features of the data.",2208.11685v1
+2022-08-31,Reynolds number effects on the bistable flows over a wavy circular cylinder,"The wake of wavy cylinder has been shown to exhibit bistability. Depending on
+the initial condition, the final state of the wake can either develop into a
+steady flow (state I), or periodic shedding (state II). In this paper, we
+perform direct numerical simulations to reveal the Reynolds number effects on
+these two wake states. With increasing Reynolds number, the steady vortical
+structures in state I wake sways back and forth in the spanwise direction,
+resulting in low-frequency fluctuations in drag forces, but not in lift. For
+state II, the increase in Reynolds number is associated with the emergence of
+another spectral peak in the lift coefficient. The secondary frequency is
+associated with highly three-dimensional vortical structures in the wake. For
+both states, the wakes transition to turblent flows at higher Reynolds numbers,
+with the development of small-scale vortices. We further study the streamwise
+gust flows over the wavy cylinder. The time-varying inflow velocity results in
+a wide range of instantaneous Reynolds number spanning from the absolutely
+unstable flow regime to the bistable regime. Depending on the period of the
+inflow velocity variation, the wake perturbations grown at the absolutely
+unstable flow regime can be damped out in state I wake, or grow large enough to
+trigger the transition state II, resulting in loss of flow control efficacy.
+The above analyses reveal novel flow physics of the bistable states at
+unexplored Reynolds numbers, and showcase the complex transition behavior
+between the two states in unsteady flows. The insights gained from this study
+improve the understanding of the wake dynamics of the wavy cylinder.",2208.14606v1
+2022-09-13,Do Periods of Decayless Kink Oscillations of Solar Coronal Loops Depend on Noise?,"Decayless kink oscillations of solar coronal loops are studied in terms of a
+low-dimensional model based on a randomly driven Rayleigh oscillator with
+coefficients experiencing random fluctuations. The model considers kink
+oscillations as natural modes of coronal loops, decaying by linear resonant
+absorption. The damping is counteracted by random motions of the loop
+footpoints and the interaction of the loop with external quasi-steady flows
+with random fluctuations. In other words, the model combines the
+self-oscillatory and randomly driven mechanisms for the decayless behaviour.
+The random signals are taken to be of the stationary red noise nature. In the
+noiseless case, the model has an asymptotically stationary oscillatory
+solution, i.e., a kink self-oscillation. It is established that the kink
+oscillation period is practically independent of noise. This finding justifies
+the seismological estimations of the kink and Alfv\'en speeds and the magnetic
+field in an oscillating loop by kink oscillations, based on the observed
+oscillation period. The oscillatory patterns are found to be almost harmonic.
+Noisy fluctuations of external flows modulate the amplitude of the almost
+monochromatic oscillatory pattern symmetrically, while random motions of the
+loop footpoints cause antisymmetric amplitude modulation. Such modulations are
+also consistent with the observed behaviour.",2209.06343v1
+2022-10-11,Switching Dynamics of Shallow Arches,"This paper presents an analytical method to predict the delayed switching
+dynamics of nonlinear shallow arches while switching from one state to another
+state for different loading cases. We study an elastic arch subject to static
+loading and time-dependent loading separately. In particular, we consider a
+time-dependent loading that evolves linearly with time at a constant rate. In
+both cases, we observed that the switching does not occur abruptly when the
+load exceeds the static switching load, rather the time scale of the dynamics
+drastically slows down; hence there is a delay in switching. For
+time-independent loading, this delay increases as the applied load approach the
+static switching load. Whereas for a time-dependent loading, the delay is
+proportional to the rate of the applied load. Other than the loading
+parameters, the delay switching time also depends on the local curvature of the
+force-displacement function at the static switching point and the damping
+coefficient of the arch material. The delay switching occurs due to the
+flatness of the energy curve at static switching load. Therefore, we linearize
+the arch near the static switching point and get a reduced nonlinear ordinary
+differential equation to study the switching dynamics of the arch. This reduced
+equation allows us to derive analytical expressions for the delay switching
+time of the. We further compare the derived analytical results with the
+numerical solutions and observed a good agreement between them. Finally, the
+derived analytical formulae can be used to design arches for self-offloading
+dynamic footwear for diabetics.",2210.05734v2
+2022-10-11,Moment-Based Approach to the Flux-Tube linear Gyrokinetic Model,"This work reports on the development and numerical implementation of the
+linear electromagnetic gyrokinetic (GK) model in a tokamak flux-tube geometry
+using a moment approach based on the expansion of the perturbed distribution
+function on a velocity-space Hermite-Laguerre polynomials basis. A hierarchy of
+equations of the expansion coefficients, referred to as the gyro-moments (GM),
+is derived. We verify the numerical implementation of the GM hierarchy in the
+collisionless limit by performing a comparison with the continuum GK code GENE,
+recovering the linear properties of the ion-temperature gradient, trapped
+electron, kinetic ballooning, and microtearing modes, as well as the
+collisionless damping of zonal flows. The present investigation reveals the
+ability of the GM approach to describe fine velocity-space scale structures
+appearing near the trapped and passing boundary and kinetic effects associated
+with parallel and perpendicular particle drifts. In addition, the effects of
+collisions are studied using advanced collision operators, including the GK
+Coulomb collision operator. The main findings are that the number of GMs
+necessary for convergence decreases with plasma collisionality and is lower for
+pressure gradient-driven modes, such as in H-mode pedestal regions, compared to
+instabilities driven by trapped particles and magnetic gradient drifts often
+found in the core. The accuracy of approximations often used to model
+collisions (relative to the GK Coulomb operator) is studied, showing
+differences between collision operator models that increase with collisionality
+and electron temperature gradient in the case of TEM. The present linear
+analysis demonstrates that the GM approach efficiently describes the plasma
+dynamics for typical parameters of the tokamak boundary, ranging from the
+low-collisionality banana H-mode to the high-collisionality Pfirsch-Schl\""uter
+conditions.",2210.05799v1
+2022-10-17,Pion dynamics in a soft-wall AdS-QCD model,"Pseudo-Goldstone modes appear in many physical systems and display robust
+universal features. First, their mass $m$ obeys the so-called
+Gell-Mann-Oakes-Renner (GMOR) relation $f^2\,m^2=H\,\bar{\sigma}$, with $f$ the
+Goldstone stiffness, $H$ the explicit breaking scale and $\bar{\sigma}$ the
+spontaneous condensate. More recently, it has been shown that their damping
+$\Omega$ is constrained to follow the relation $\Omega=m^2 D_\varphi$, where
+$D_\varphi$ is the Goldstone diffusivity in the purely spontaneous phase. Pions
+are the most paradigmatic example of pseudo-Goldstone modes and they are
+related to chiral symmetry breaking in QCD. In this work, we consider a
+bottom-up soft-wall AdS-QCD model with broken ${\rm{SU}}(2)_L \times
+{\rm{SU}}(2)_R$ symmetry and we study the nature of the associated
+pseudo-Goldstone modes -- the pions. In particular, we perform a detailed
+investigation of their dispersion relation in presence of dissipation, of the
+role of the explicit breaking induced by the quark masses and of the dynamics
+near the critical point. Taking advantage of the microscopic information
+provided by the holographic model, we give quantitative predictions for all the
+coefficients appearing in the effective description. In particular, we estimate
+the finite temperature behavior of the kinetic parameter $\mathfrak{r^2}$
+defined as the ration between the Goldstone diffusivity $D_\varphi$ and the
+pion attenuation constant $D_A$. Interestingly, we observe important deviations
+from the value $\mathfrak{r^2}=3/4$ computed in chiral perturbation theory in
+the limit of zero temperature.",2210.09088v1
+2022-11-03,Viscous attenuation of gravitational waves propagating through an inhomogeneous background,"We consider the propagation of gravitational waves in the late-time Universe
+in the presence of matter distribution inhomogeneities, and we also consider
+the cosmic fluid to be viscous. In this work, we investigate the cumulative
+effect of inhomogeneities and viscosity of the cosmic-fluid on the observables
+associated with the sources of the gravitational waves. Employing Buchert's
+averaging procedure in the backreaction framework, we consider a model of
+spacetime in which matter is distributed in-homogeneously across space. Using
+the modified redshift versus distance relation, through the averaging process
+in the context of the model, we study the variation of the redshift-dependent
+part of the observed gravitational wave amplitude for different combinations of
+our model parameters while simultaneously considering damping of the
+gravitational wave amplitude due to viscosity of the cosmic-fluid. Then, we
+investigate the differences occurring in the variation of the
+redshift-dependent part of the observed gravitational wave amplitude due to
+consideration of viscous attenuation. We show that there are significant
+deviations after the inclusion of viscous attenuation in our analysis,
+depending on the chosen value of the coefficient of viscosity. Our result
+signifies the importance of the effect of viscosity, within the model of an
+inhomogeneous Universe, on precision measurements of parameters of
+compact-binary sources of gravitational waves.",2211.01652v3
+2022-11-07,Three-Dimensionality in the flow of an elastically mounted circular cylinder with two-degree-of-freedom vortex-induced-vibrations,"The study numerically investigates the three-dimensionality in the flow and
+two-degree-of-freedom (2 DOF) vortex-induced-vibrations (VIV) characteristics
+of an elastically mounted circular cylinder. The cylinder is allowed to vibrate
+in both streamwise and transverse directions. A low value of mass-ratio with
+the zero damping coefficient is taken for the simulations. The primary aim is
+to understand the vortex shedding behind the cylinder and the transition
+characteristics of the wake-flow from two-dimensional (2D) to three-dimensional
+(3D). The Reynolds number (Re) is varied from 150 (fully 2D flow) to 1000
+(fully 3D flow), which lies inside the laminar range. The reduced velocity is
+varied which covers all three major VIV branches (Initial Branch (IB), Upper
+Branch (UB), and the Lower Branch (LB)). The oscillating cylinder sweeps the
+figure-eight trajectory. Two branches (IB, LB) and three branches (IB, UB, LB)
+amplitude responses are obtained for the low and high Re values, respectively.
+The wake behind the cylinder with 2-DOF VIV undergoes the mode-C transition of
+2D to 3D flow as opposed to the direct mode-B transition observed for
+transverse only VIV in the literature. The critical Re range of the 2D to 3D
+transition for the 2-DOF VIV cylinder at a reduced velocity of 6 is around 250,
+less than the 1-DOF VIV. Also, this range varies with the variation in and the
+streamwise to transverse oscillation frequency ratio. A map is proposed for the
+2-DOF VIV, highlighting the different modes of transition obtained for
+combinations of reduced frequency and Re.",2211.03307v1
+2022-11-10,Nonreciprocal nanoparticle refrigerators: design principles and constraints,"We study the heat transfer between two nanoparticles held at different
+temperatures that interact through nonreciprocal forces, by combining molecular
+dynamics simulations with stochastic thermodynamics. Our simulations reveal
+that it is possible to construct nano refrigerators that generate a net heat
+transfer from a cold to a hot reservoir at the expense of power exerted by the
+nonreciprocal forces. Applying concepts from stochastic thermodynamics to a
+minimal under-damped Langevin model, we derive exact analytical expressions
+predictions for the fluctuations of work, heat, and efficiency, which reproduce
+thermodynamic quantities extracted from the molecular dynamics simulations. The
+theory only involves a single unknown parameter, namely an effective friction
+coefficient, which we estimate fitting the results of the molecular dynamics
+simulation to our theoretical predictions. Using this framework, we also
+establish design principles which identify the minimal amount of entropy
+production that is needed to achieve a certain amount of uncertainty in the
+power fluctuations of our nano refrigerator. Taken together, our results shed
+light on how the direction and fluctuations of heat flows in natural and
+artificial nano machines can be accurately quantified and controlled by using
+nonreciprocal forces.",2211.05502v3
+2022-11-11,Chemical Mixing Induced by Internal Gravity Waves in Intermediate Mass Stars,"Internal gravity waves (IGWs) can cause mixing in the radiative interiors of
+stars. We study this mixing by introducing tracer particles into two -
+dimensional (2D) hydrodynamic simulations. Following the work of Rogers &
+McElwaine (2017), arXiv:1709.04920, we extend our study to different masses (3
+M$_{\odot}$, 7 M$_{\odot}$ and 20 M$_{\odot}$) and ages (ZAMS, midMS and TAMS).
+The diffusion profiles of these models are influenced by various parameters
+such as the Brunt-V\""ais\""al\""a frequency, density, thermal damping, the
+geometric effect and the frequencies of waves contributing to these mixing
+profiles. We find that the mixing profile changes dramatically across age. In
+younger stars, we noted that the diffusion coefficient increases towards the
+surface, whereas in older stars the initial increase in the diffusion profile
+is followed by a decreasing trend. We also find that mixing is stronger in more
+massive stars. Hence, future stellar evolution models should include this
+variation. In order to aid the inclusion of this mixing in one-dimensional (1D)
+stellar evolution models, we determine the dominant waves contributing to these
+mixing profiles and present a prescription that can be included in 1D models.",2211.06432v1
+2023-06-20,A revised gap-averaged Floquet analysis of Faraday waves in Hele-Shaw cells,"Existing theoretical analyses of Faraday waves in Hele-Shaw cells rely on the
+Darcy approximation and assume a parabolic flow profile in the narrow
+direction. However, Darcy's model is known to be inaccurate when convective or
+unsteady inertial effects are important. In this work, we propose a
+gap-averaged Floquet theory accounting for inertial effects induced by the
+unsteady terms in the Navier-Stokes equations, a scenario that corresponds to a
+pulsatile flow where the fluid motion reduces to a two-dimensional oscillating
+Poiseuille flow, similarly to the Womersley flow in arteries. When
+gap-averaging the linearized Navier-Stokes equation, this results in a modified
+damping coefficient, which is a function of the ratio between the Stokes
+boundary layer thickness and the cell's gap, and whose complex value depends on
+the frequency of the wave response specific to each unstable parametric region.
+We first revisit the standard case of horizontally infinite rectangular
+Hele-Shaw cells by also accounting for a dynamic contact angle model. A
+comparison with existing experiments shows the predictive improvement brought
+by the present theory and points out how the standard gap-averaged model often
+underestimates the Faraday threshold. The analysis is then extended to the less
+conventional case of thin annuli. A series of dedicated experiments for this
+configuration highlights how Darcy's thin-gap approximation overlooks a
+frequency detuning that is essential to correctly predict the locations of the
+Faraday tongues in the frequency-amplitude parameter plane. These findings are
+well rationalized and captured by the present model.",2306.11501v1
+2023-07-04,Exponential stability of Euler-Bernoulli beam under boundary controls in rotation and angular velocity,"This paper addresses the analysis of a boundary feedback system involving a
+non-homogeneous Euler-Bernoulli beam governed by the equation
+$m(x)u_{tt}+\mu(x)u_{t}$$+\left(r(x)u_{xx}\right)_{xx}=0$, subject to the
+initial $u(x,0)=u_0(x)$, $u_t(x,0)=v_0(x)$ and boundary conditions $u(0,t)=0$,
+$\left (-r(x)u_{xx}(x,t)\right )_{x=0}=-k^{-}_r u_{x}(0,t)-k^{-}_a
+u_{xt}(0,t)$, $u(\ell,t)=0$, $\left (-r(x)u_{xx}(x,t)\right )_{x=\ell}=-k^{+}_r
+u_{x}(\ell,t)-k^{+}_a u_{xt}(\ell,t)$, with boundary control at both ends
+resulting from the rotation and angular velocity. The approach proposed in this
+study relies on the utilization of regular weak solutions, energy identity, and
+a physically motivated Lyapunov function. By imposing natural assumptions
+concerning physical parameters and other inputs, which ensure the existence of
+a regular weak solution, we successfully derive a uniform exponential decay
+estimate for the system's energy. The decay rate constant featured in this
+estimate is solely dependent on the physical and geometric properties of the
+beam. These properties encompass crucial parameters such as the viscous
+external damping coefficient $\mu(x)$, as well as the boundary springs
+$k^{-}_r,k^+_r $ and dampers $k^{-}_a,k^+_a$. To illustrate the practical
+effectiveness of our theoretical findings, numerical examples are provided.
+These examples serve to demonstrate the applicability and relevance of our
+derived results in real-world scenarios.",2307.01518v1
+2023-07-10,Full-F Turbulent Simulation in a Linear Device using a Gyro-Moment Approach,"Simulations of plasma turbulence in a linear plasma device configuration are
+presented. These simulations are based on a simplified version of the
+gyrokinetic (GK) model proposed by B. J. Frei et al. [J. Plasma Phys. 86,
+905860205 (2020)] where the full-F distribution function is expanded on a
+velocity-space polynomial basis allowing us to reduce its evolution to the
+solution of an arbitrary number of fluid-like equations for the expansion
+coefficients, denoted as the gyro-moments (GM). By focusing on the
+electrostatic and neglecting finite Larmor radius effects, a full-F GM
+hierarchy equation is derived to evolve the ion dynamics, which includes a
+nonlinear Dougherty collision operator, localized sources, and Bohm sheath
+boundary conditions. An electron fluid Braginskii model is used to evolve the
+electron dynamics, coupled to the full-F ion GM hierarchy equation via a
+vorticity equation where the Boussinesq approximation is used. A set of full-F
+turbulent simulations are then performed using the parameters of the LArge
+Plasma Device (LAPD) experiments with different numbers of ion GMs and
+different values of collisionality. The ion distribution function is analyzed
+illustrating the convergence properties of the GM approach. In particular, we
+show that higher-order GMs are damped by collisions in the high-collisional
+regime relevant to LAPD experiments. The GM results are then compared with
+those from two-fluid Braginskii simulations, finding qualitative agreement in
+the time-averaged profiles and statistical turbulent properties.",2307.04562v2
+2023-07-12,Robust scalable initialization for Bayesian variational inference with multi-modal Laplace approximations,"For predictive modeling relying on Bayesian inversion, fully independent, or
+``mean-field'', Gaussian distributions are often used as approximate
+probability density functions in variational inference since the number of
+variational parameters is twice the number of unknown model parameters. The
+resulting diagonal covariance structure coupled with unimodal behavior can be
+too restrictive when dealing with highly non-Gaussian behavior, including
+multimodality. High-fidelity surrogate posteriors in the form of Gaussian
+mixtures can capture any distribution to an arbitrary degree of accuracy while
+maintaining some analytical tractability. Variational inference with Gaussian
+mixtures with full-covariance structures suffers from a quadratic growth in
+variational parameters with the number of model parameters. Coupled with the
+existence of multiple local minima due to nonconvex trends in the loss
+functions often associated with variational inference, these challenges
+motivate the need for robust initialization procedures to improve the
+performance and scalability of variational inference with mixture models.
+  In this work, we propose a method for constructing an initial Gaussian
+mixture model approximation that can be used to warm-start the iterative
+solvers for variational inference. The procedure begins with an optimization
+stage in model parameter space in which local gradient-based optimization,
+globalized through multistart, is used to determine a set of local maxima,
+which we take to approximate the mixture component centers. Around each mode, a
+local Gaussian approximation is constructed via the Laplace method. Finally,
+the mixture weights are determined through constrained least squares
+regression. Robustness and scalability are demonstrated using synthetic tests.
+The methodology is applied to an inversion problem in structural dynamics
+involving unknown viscous damping coefficients.",2307.06424v1
+2023-09-26,Universal Pairwise Interatomic van der Waals Potentials Based on Quantum Drude Oscillators,"Repulsive short-range and attractive long-range van der Waals (vdW) forces
+have an appreciable role in the behavior of extended molecular systems. When
+using empirical force fields - the most popular computational methods applied
+to such systems - vdW forces are typically described by Lennard-Jones-like
+potentials, which unfortunately have a limited predictive power. Here, we
+present a universal parameterization of a quantum-mechanical vdW potential,
+which requires only two free-atom properties - the static dipole polarizability
+$\alpha_1$ and the dipole-dipole $C_6$ dispersion coefficient. This is achieved
+by deriving the functional form of the potential from the quantum Drude
+oscillator (QDO) model, employing scaling laws for the equilibrium distance and
+the binding energy as well as applying the microscopic law of corresponding
+states. The vdW-QDO potential is shown to be accurate for vdW binding energy
+curves, as demonstrated by comparing to ab initio binding curves of 21
+noble-gas dimers. The functional form of the vdW-QDO potential has the correct
+asymptotic behavior both at zero and infinite distances. In addition, it is
+shown that the damped vdW-QDO potential can accurately describe vdW
+interactions in dimers consisting of group II elements. Finally, we demonstrate
+the applicability of the atom-in-molecule vdW-QDO model for predicting accurate
+dispersion energies for molecular systems. The present work makes an important
+step towards constructing universal vdW potentials, which could benefit
+(bio)molecular computational studies.",2309.14910v1
+2023-10-18,Quartic scaling of sound attenuation with frequency in vitreous silica,"Several theoretical approaches to disordered media predict that acoustic
+waves should undergo a quartic increase in their attenuation coefficient with
+increasing frequency in the sub-terahertz region. Such Rayleigh-type scattering
+would be related to the anomalous low-temperature plateau in the thermal
+conductivity and to the so-called boson peak, i.e. an excess of vibrational
+modes above the Debye density of states at around 1 THz. Brillouin scattering
+of light allows the measurement of sound absorption and velocity dispersion up
+to about 0.1 THz while inelastic x-ray scattering is limited to frequencies
+larger than about 1 THz. We take advantage of the advent of ultrafast optical
+techniques to explore the acoustical properties of amorphous SiO2 layers in the
+difficult but crucial frequency region within this gap. A quartic scaling law
+with frequency is clearly revealed between 0.2 and 0.9 THz, which is further
+shown to be independent of temperature. This strongly damped regime is
+accompanied by a decrease in the sound velocity already starting from about 0.5
+THz, in line with theories. Our study assists to clarify the anomalous
+acoustical properties in glasses at frequencies entering the boson peak region.",2310.11832v1
+2023-11-11,Effects of wave parameters on load reduction performance for amphibious aircraft with V-hydrofoil,"An investigation of the influence of the hydrofoil on load reduction
+performance during an amphibious aircraft landing on still and wavy water is
+conducted by solving the Unsteady Reynolds-Averaged Navier-Stokes equations
+coupled with the standard $k-\omega$ turbulence model in this paper. During the
+simulations, the numerical wave tank is realized by using the velocity-inlet
+boundary wave maker coupled with damping wave elimination technique on the
+outlet, while the volume of fluid model is employed to track the water-air
+interface. Subsequently, the effects of geometric parameters of hydrofoil have
+been first discussed on still water, which indicates the primary factor
+influencing the load reduction is the static load coefficient of hydrofoil.
+Furthermore, the effects of descent velocity, wave length and wave height on
+load reduction are comprehensively investigated. The results show that the
+vertical load reduces more than 55$\%$ at the early stage of landing on the
+still water through assembling the hydrofoil for different descent velocity
+cases. Meanwhile, for the amphibious aircraft with high forward velocity, the
+bottom of the fuselage will come into close contact with the first wave when
+landing on crest position, and then the forebody will impact the next wave
+surface with extreme force. In this circumstance, the load reduction rate
+decreases to around 30$\%$, which will entail a further decline with the
+increase of wave length or wave height.",2311.06516v1
+2023-11-17,Simulating X-ray Reverberation in the UV-Emitting Regions of Active Galactic Nuclei Accretion Disks with 3D Multi-Frequency Magnetohydrodynamic Simulations,"Active galactic nuclei (AGN) light curves observed with different wavebands
+show that the variability in longer wavelength bands lags the variability in
+shorter wavelength bands. Measuring these lags, or reverberation mapping, is
+used to measure the radial temperature profile and extent of AGN disks,
+typically with a reprocessing model that assumes X-rays are the main driver of
+the variability in other wavelength bands. To demonstrate how this reprocessing
+works with realistic accretion disk structures, we use 3D local shearing box
+multi-frequency radiation magnetohydrodynamic (MHD) simulations to model the
+UV-emitting region of an AGN disk, which is unstable to the magnetorotational
+instability (MRI) and convection. At the same time, we inject hard X-rays
+($>1$~keV) into the simulation box to study the effects of X-ray irradiation on
+the local properties of the turbulence and the resulting variability of the
+emitted UV light curve. We find that disk turbulence is sufficient to drive
+intrinsic variability in emitted UV light curves and that a damped random walk
+(DRW) model is a good fit to this UV light curve for timescales $>5$~days.
+Meanwhile, the injected X-rays have almost no impact on the power spectrum of
+the emitted UV light curve. In addition, the injected X-ray and emitted UV
+light curves are only correlated if there is X-ray variability on timescales
+$>1$~day, in which case we find a correlation coefficient $r=0.52$. These
+results suggest that hard X-rays with scattering dominated opacity are likely
+not the main driver of the reverberation signals.",2311.10820v1
+2023-11-25,Ultrasensitive vibrational resonance induced by small disturbances,"We have found two kinds of ultra-sensitive vibrational resonance in coupled
+nonlinear systems. It is particularly worth pointing out that this
+ultra-sensitive vibrational resonance is a transient behavior caused by
+transient chaos. Considering long-term response, the system will transform from
+transient chaos to periodic response. The pattern of vibrational resonance will
+also transform from ultra-sensitive vibrational resonance to conventional
+vibrational resonance. This article focuses on the transient ultra-sensitive
+vibrational resonance phenomenon. It is induced by a small disturbance of the
+high-frequency excitation and the initial simulation conditions, respectively.
+The damping coefficient and the coupling strength are the key factors to induce
+the ultra-sensitive vibrational resonance. By increasing these two parameters,
+the vibrational resonance pattern can be transformed from an ultra-sensitive
+vibrational resonance to a conventional vibrational resonance. The reason for
+different vibrational resonance patterns to occur lies in the state of the
+system response. The response usually presents transient chaotic behavior when
+the ultra-sensitive vibrational resonance appears and the plot of the response
+amplitude versus the controlled parameters shows a highly fractalized pattern.
+When the response is periodic or doubly-periodic, it usually corresponds to the
+conventional vibrational resonance. The ultra-sensitive vibrational resonance
+not only occurs at the excitation frequency, but it also occurs at some more
+nonlinear frequency components. The ultra-sensitive vibrational resonance as a
+transient behavior and the transformation of vibrational resonance patterns are
+new phenomena in coupled nonlinear systems.",2312.11474v1
+2024-02-13,Hyperballistic transport in dense ionized matter under external AC electric fields,"The Langevin equation is ubiquitously employed to numerically simulate
+plasmas and dusty plasmas. However, the usual assumption of white noise becomes
+untenable when the system is subject to an external AC electric field. This is
+because the charged particles in the plasma, which provide the thermal bath for
+the particle transport, become themselves responsive to the AC field and the
+thermal noise is field-dependent and non-Markovian. We theoretically study the
+particle diffusivity in a Langevin transport model for a tagged charged
+particle immersed in a dense plasma of charged particles that act as the
+thermal bath, under an external AC electric field, by properly accounting for
+the effects of the AC field on the thermal bath statistics. We analytically
+derive the time-dependent generalized diffusivity $D(t)$ for different initial
+conditions. The generalized diffusivity exhibits damped oscillatory-like
+behaviour with initial very large peaks, where the generalized diffusion
+coefficient is enhanced by orders of magnitude with respect to the
+infinite-time steady-state value. The latter coincides with the Stokes-Einstein
+diffusivity in the absence of external field. For initial conditions where the
+external field is already on at $t=0$ and the system is thermalized under DC
+conditions for $t \leq 0$, the short-time behaviour is hyperballistic, $MSD
+\sim t^4$ (where MSD is the mean-squared displacement), leading to giant
+enhancement of the particle transport. Finally, the theory elucidates the role
+of medium polarization on the local Lorentz field, and allows for estimates of
+the effective electric charge due to polarization by the surrounding charges.",2402.08519v2
+2024-02-15,Tracer dynamics in polymer networks: generalized Langevin description,"Tracer diffusion in polymer networks and hydrogels is relevant in biology and
+technology, while it also constitutes an interesting model process for the
+dynamics of molecules in fluctuating, heterogeneous soft matter. Here, we study
+systematically the time-dependent dynamics and (non-Markovian) memory effects
+of tracers in polymer networks based on (Markovian) implicit-solvent Langevin
+simulations. In particular, we consider spherical tracer solutes at high
+dilution in regular, tetrafunctional bead-spring polymer networks, and control
+the tracer-network Lennard-Jones (LJ) interactions and the polymer density.
+Based on the analysis of the memory (friction) kernels, we recover the expected
+long-time transport coefficients, and demonstrate how the short-time tracer
+dynamics, polymer fluctuations, and the viscoelastic response are interlinked.
+Further, we fit the characteristic memory modes of the tracers with damped
+harmonic oscillations and identify LJ contributions, bond vibrations, and slow
+network relaxations, which enter the kernel with an almost linear scaling with
+the LJ attractions. This procedure proposes a reduced functional form for the
+tracer memory, allowing for a convenient inter- and extrapolation of the memory
+kernels. This leads eventually to highly efficient simulations utilizing the
+generalized Langevin equation (GLE), in which the polymer network acts as an
+additional thermal bath with tuneable intensity.",2402.10148v1
+2024-02-21,Obstacle crossing strategies for high-speed 4WD small-scale vehicle,"Unmanned ground vehicle obstacle crossing generally relies on two strategies:
+(i) applying a wheel torque for climbing and (ii) modifying the vehicle shape
+by using a wheel-leg or wheel-paddle to lift the wheel on top of the obstacle.
+However, most of those strategies sacrifice speed in order to have a longer
+contact duration between the wheels and the obstacle. This paper investigates
+the behaviour of a 4WD high-speed vehicle while crossing a step obstacle using
+a design of experiment (DoE). A 3D multibody vehicle model is equipped with a
+novel 2-DoF suspension system, which horizontal damping coefficient is modify
+to dampen wheel motion in longitudinal and vertical directions in relation to
+the chassis, for a given speed and obstacle height. The DoE results allow to
+propose a novel high-speed obstacle crossing strategy based on three metrics:
+(i) the kinetic energy variation of the vehicle, (ii) the contact duration
+between the wheel and the obstacle, and (iii) the pitch rate at the start of
+the ballistic phase. Experimental function are proposed to be able modify these
+metric in real time.",2402.13650v1
+2001-08-02,Dielectronic Recombination (via N=2 --> N'=2 Core Excitations) and Radiative Recombination of Fe XX: Laboratory Measurements and Theoretical Calculations,"We have measured the resonance strengths and energies for dielectronic
+recombination (DR) of Fe XX forming Fe XIX via N=2 --> N'=2 (Delta_N=0) core
+excitations. We have also calculated the DR resonance strengths and energies
+using AUTOSTRUCTURE, HULLAC, MCDF, and R-matrix methods, four different
+state-of-the-art theoretical techniques. On average the theoretical resonance
+strengths agree to within <~10% with experiment. However, the 1 sigma standard
+deviation for the ratios of the theoretical-to-experimental resonance strengths
+is >~30% which is significantly larger than the estimated relative experimental
+uncertainty of <~10%. This suggests that similar errors exist in the calculated
+level populations and line emission spectrum of the recombined ion. We confirm
+that theoretical methods based on inverse-photoionization calculations (e.g.,
+undamped R-matrix methods) will severely overestimate the strength of the DR
+process unless they include the effects of radiation damping. We also find that
+the coupling between the DR and radiative recombination (RR) channels is small.
+We have used our experimental and theoretical results to produce
+Maxwellian-averaged rate coefficients for Delta_N=0 DR of Fe XX. For kT>~1 eV,
+which includes the predicted formation temperatures for Fe XX in an optically
+thin, low-density photoionized plasma with cosmic abundances, our experimental
+and theoretical results are in good agreement. We have also used our R-matrix
+results, topped off using AUTOSTRUCTURE for RR into J>=25 levels, to calculate
+the rate coefficient for RR of Fe XX. Our RR results are in good agreement with
+previously published calculations.",0108048v1
+2003-10-21,Self-Consistent R-matrix Approach To Photoionization And Unified Electron-Ion Recombination,"A unified scheme using the R-matrix method has been developed for
+electron-ion recombination subsuming heretofore separate treatments of
+radiative and dielectronic recombination (RR and DR). The ab initio coupled
+channel approach unifies resonant and non-resonant phenomena, and enables a
+general and self-consistent treatment of photoionization and electron-ion
+recombination employing idential wavefunction expansion. Detailed balance takes
+account of interference effects due to resonances in cross sections, calculated
+explicitly for a large number of recombined (e+ion) bound levels over extended
+energy regions. The theory of DR by Bell and Seaton is adapted for high-n
+resonances in the region below series limits. The R-matrix method is employed
+for (A) partial and total photoionization and photorecombination cross sections
+of (e+ion) bound levels, and (B) DR and (e+ion) scattering cross sections.
+Relativistic effects and fine structure are considered in the Breit-Pauli
+approximation. Effects such as radiation damping may be taken into account
+where necessary. Unfiied recombination cross sections are in excellent
+agreement with measurements on ion storage rings to about 10-20%. In addition
+to high accuracy, the strengths of the method are: (I) both total and
+level-specific cross sections and rate coefficients are obtained, and (II) a
+single (e+ion) recombination rate coefficient for any given atom or ion is
+obtained over the entire temperature range of practical importance in
+laboratory and astrophysical plasmas, (III) self-consistent results are
+obtained for photoionization and recombination; comprehensive datasets have
+been computed for over 50 atoms and ions. Selected data are presented for iron
+ions.",0310624v1
+2001-10-19,A Survey of Numerical Solutions to the Coagulation Equation,"We present the results of a systematic survey of numerical solutions to the
+coagulation equation for a rate coefficient of the form A_ij \propto (i^mu j^nu
++ i^nu j^mu) and monodisperse initial conditions. The results confirm that
+there are three classes of rate coefficients with qualitatively different
+solutions. For nu \leq 1 and lambda = mu + nu \leq 1, the numerical solution
+evolves in an orderly fashion and tends toward a self-similar solution at large
+time t. The properties of the numerical solution in the scaling limit agree
+with the analytic predictions of van Dongen and Ernst. In particular, for the
+subset with mu > 0 and lambda < 1, we disagree with Krivitsky and find that the
+scaling function approaches the analytically predicted power-law behavior at
+small mass, but in a damped oscillatory fashion that was not known previously.
+For nu \leq 1 and lambda > 1, the numerical solution tends toward a
+self-similar solution as t approaches a finite time t_0. The mass spectrum n_k
+develops at t_0 a power-law tail n_k \propto k^{-tau} at large mass that
+violates mass conservation, and runaway growth/gelation is expected to start at
+t_crit = t_0 in the limit the initial number of particles n_0 -> \infty. The
+exponent tau is in general less than the analytic prediction (lambda + 3)/2,
+and t_0 = K/[(lambda - 1) n_0 A_11] with K = 1--2 if lambda > 1.1. For nu > 1,
+the behaviors of the numerical solution are similar to those found in a
+previous paper by us. They strongly suggest that there are no self-consistent
+solutions at any time and that runaway growth is instantaneous in the limit n_0
+-> \infty. They also indicate that the time t_crit for the onset of runaway
+growth decreases slowly toward zero with increasing n_0.",0110411v1
+2003-11-08,Memory effects in superfluid vortex dynamics,"The dissipative dynamics of a vortex line in a superfluid is investigated
+within the frame of a non-Markovian quantal Brownian motion model. Our starting
+point is a recently proposed interaction Hamiltonian between the vortex and the
+superfluid quasiparticle excitations, which is generalized to incorporate the
+effect of scattering from fermion impurities ($^3$He atoms). Thus, a
+non-Markovian equation of motion for the mean value of the vortex position
+operator is derived within a weak-coupling approximation. Such an equation is
+shown to yield, in the Markovian and elastic scattering limits, a $^3$He
+contribution to the longitudinal friction coefficient equivalent to that
+arising from the Rayfield-Reif formula. Simultaneous Markov and elastic
+scattering limits are found, however, to be incompatible, since an unexpected
+breakdown of the Markovian approximation is detected at low cyclotron
+frequencies. Then, a non-Markovian expression for the longitudinal friction
+coefficient is derived and computed as a function of temperature and $^3$He
+concentration. Such calculations show that cyclotron frequencies within the
+range 0.01$-$0.03 ps$^{-1}$ yield a very good agreement to the longitudinal
+friction figures computed from the Iordanskii and Rayfield-Reif formulas for
+pure $^4$He, up to temperatures near 1 K. A similar performance is found for
+nonvanishing $^3$He concentrations, where the comparison is also shown to be
+very favorable with respect to the available experimental data. Memory effects
+are shown to be weak and increasing with temperature and concentration.",0311179v3
+2015-09-03,Evidence of thermal conduction suppression in a solar flaring loop by coronal seismology of slow-mode waves,"Analysis of a longitudinal wave event observed by the Atmospheric Imaging
+Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) is presented. A
+time sequence of 131 A images reveals that a C-class flare occurred at one
+footpoint of a large loop and triggered an intensity disturbance (enhancement)
+propagating along it. The spatial features and temporal evolution suggest that
+a fundamental standing slow-mode wave could be set up quickly after meeting of
+two initial disturbances from the opposite footpoints. The oscillations have a
+period of ~12 min and a decay time of ~9 min. The measured phase speed of
+500$\pm$50 km/s matches the sound speed in the heated loop of ~10 MK,
+confirming that the observed waves are of slow mode. We derive the
+time-dependent temperature and electron density wave signals from six AIA
+extreme-ultraviolet (EUV) channels, and find that they are nearly in phase.The
+measured polytropic index from the temperature and density perturbations is
+1.64$\pm$0.08 close to the adiabatic index of 5/3 for an ideal monatomic gas.
+The interpretation based on a 1D linear MHD model suggests that the thermal
+conductivity is suppressed by at least a factor of 3 in the hot flare loop at 9
+MK and above. The viscosity coefficient is determined by coronal seismology
+from the observed wave when only considering the compressive viscosity
+dissipation. We find that to interpret the rapid wave damping, the classical
+compressive viscosity coefficient needs to be enhanced by a factor of 15 as the
+upper limit.",1509.00920v2
+2016-12-07,Ab initio quantum-statistical approach to kinetic theory of low-temperature dilute gases of hydrogen-like atoms,"We develop a microscopic approach to the consistent construction of the
+kinetic theory of dilute weakly ionized gases of hydrogen-like atoms. The
+approach is based on the framework of the second quantization method in the
+presence of bound states of particles and the method of reduced description of
+relaxation processes. Within the approach we developed the first-order
+perturbation theory over the weak interaction for a system of kinetic equations
+for the Wigner distribution functions of free fermions of both kinds and their
+bound states, the hydrogen-like atoms. It is shown that the conditions of
+low-temperature approximation, of the gas non-degeneracy and the approximation
+of weak interaction are realistic and can be met in a wide range of
+temperatures and the densities of the studied system. We obtain dispersion
+equations for determining the frequency and wave attenuation coefficients in
+dilute weakly ionized gas of hydrogen-like atoms near the described equilibrium
+state. In the two-level atom approximation it is shown that in the system there
+are longitudinal waves of matter polarization and transverse waves with the
+behavior characteristic of plasmon polaritons. The expressions for the
+dependence of the frequency and the Landau damping coefficients on the wave
+vector for all branches of the oscillations detected, are obtained.
+Quantitative estimations of the characteristics of the elementary perturbations
+in the system on an example of a weakly ionized dilute gas of Na-23 atoms are
+presented. The possibility of using the results of the theory developed to
+describe the properties of a Bose condensate of photons in dilute weakly
+ionized gas of hydrogen-like atoms is noted and the directions of its
+generalizations are discussed.",1612.02245v1
+2018-07-27,Phase spreading and temporal coherence of a pair-condensed Fermi gas at low temperature,"A condensate of pairs in an isolated, homogeneous, unpolarised, finite-size
+spin 1/2 Fermi gas at low nonzero temperature T, undergoes with time a phase
+change with a random component, due to coupling to the gas thermal phonons.
+With the quantum second Josephson relation relating the derivative of the
+condensate phase operator to the phonon occupation numbers, and linearised
+kinetic equations giving the evolution of occupation number fluctuations, we
+access the behaviour of the phase change variance at times much longer than the
+phonon collision time. The case of a convex phonon branch is similar to the
+Bose gas case: the leading collisional processes are the Beliaev-Landau
+3-phonons processes, and the variance is the sum of a ballistic term and of a
+delayed diffusive term, whose analytical expressions are given in the
+thermodynamic limit. The concave case is more exotic. It is analysed at time
+scales $T^{-9}$, allowing one to restrict to 2 phonons $\rightarrow$ 2 phonons
+small-angle Landau-Khalatnikov processes. The total number of phonons is
+conserved and the phonon mean occupation numbers at equilibrium can exhibit a
+negative chemical potential, assumed isotropic. The phase change variance is
+then the sum of a ballistic term, of a diffusive term, of exotic subsubleading
+terms and of a constant term. The analytic expression of some of the
+corresponding coefficients is obtained, as well as the diverging leading
+behavior of the other ones when the phonon chemical potential tends to 0. When
+this chemical potential is 0, the variance sub-ballistic part becomes
+superdiffusive, with an exponent 5/3 and an exactly-known coefficient. For a
+nonzero infinitesimal phonon chemical potential, a law is found, interpolating
+between superdiffusive and diffusive phase spreading. Also new results are
+obtained on the phonon Landau-Khalatnikov damping rate, in particular at
+negative phonon chemical potential.",1807.10476v2
+2019-08-14,Comparison of wave-structure interaction dynamics of a submerged cylindrical point absorber with three degrees of freedom using potential flow and computational fluid dynamics models,"In this paper we compare the heave, surge, and pitch dynamics of a submerged
+cylindrical point absorber, simulated using potential flow and fully-resolved
+computational fluid dynamics (CFD) models. The potential flow model is based on
+the time-domain Cummins equation, whereas the CFD model uses the fictitious
+domain Brinkman penalization (FD/BP) technique. The submerged cylinder is
+tethered to the seabed using a power take-off (PTO) unit which restrains the
+heave, surge, and pitch motions of the converter, and absorbs energy from all
+three modes. It is demonstrated that the potential theory over-predicts the
+amplitudes of heave and surge motions, whereas it results in an insignificant
+pitch for a fully-submerged axisymmetric converter. It also under-estimates the
+slow drift of the buoy, which the CFD model is able to capture reliably.
+Further, we use fully-resolved CFD simulations to study the performance of a
+three degrees of freedom (DOF) cylindrical buoy under varying PTO coefficients,
+mass density of the buoy, and incoming wave heights. It is demonstrated that
+the PTO coefficients predicted by the linear potential theory are sub-optimal
+for waves of moderate and high steepness. The wave absorption efficiency
+improves significantly when higher than the predicted value of the PTO damping
+is selected. Simulations with different mass densities of the buoy show that
+converters with low mass densities have an increased tension in their PTO and
+mooring lines. Moreover, the mass density also influences the range of
+resonance periods of the device. Finally, simulations with different wave
+heights show that at higher heights, the wave absorption efficiency of the
+converter decreases and a large portion of available wave power remains
+unabsorbed.",1908.04981v4
+2019-09-13,Multi-Particle Collisions in Microgravity: Coefficient of Restitution and Sticking Threshold for Systems of Mm-Sized Particles,"The current model of planet formation lacks a good understanding of the
+growth of dust particles inside the protoplanetary disk beyond mm sizes. In
+order to investigate the low-velocity collisions between this type of
+particles, the NanoRocks experiment was flown on the International Space
+Station (ISS) between September 2014 and March 2016. We present the results of
+this experiment. We quantify the damping of energy in systems of multiple
+particles in the 0.1 to 1 mm size range while they are in the bouncing regime,
+and study the formation of clusters through sticking collisions between
+particles. We developed statistical methods for the analysis of the large
+quantity of collision data collected by the experiment. We measured the average
+motion of particles, the moment of clustering, and the cluster size formed. In
+addition, we ran simple numerical simulations in order to validate our
+measurements. We computed the average coefficient of restitution (COR) of
+collisions and find values ranging from 0.55 for systems including a population
+of fine grains to 0.94 for systems of denser particles. We also measured the
+sticking threshold velocities and find values around 1 cm/s, consistent with
+the current dust collision models based on independently collected experimental
+data. Our findings have the following implications that can be useful for the
+simulation of particles in PPDs and planetary rings: (1) The average COR of
+collisions between same-sized free-floating particles at low speeds (< 2 cm/s)
+is not dependent on the collision velocity; (2) The simplified approach of
+using a constant COR value will accurately reproduce the average behavior of a
+particle system during collisional cooling; (3) At speeds below 5 mm/s, the
+influence of particle rotation becomes apparent on the collision behavior; (4)
+Current dust collision models predicting sticking thresholds are robust.",1909.06417v1
+2020-03-20,A comparison of wave observations in the Arctic marginal ice zone with spectral models,"Increased economic activity and research interest in the Arctic raise the
+need for better wave forecasts in the marginal ice zone (MIZ). Mathematical and
+numerical models of wave propagation in sea ice would benefit from more in situ
+data for validation. This study presents shipborne wave measurements from the
+MIZ where altimeter readings are corrected for ship motion to obtain estimated
+single point ocean surface elevation. From the combined measurements, we obtain
+significant wave height and zero up-crossing period, as well as one-dimensional
+wave spectra. In addition, we provide spectra and integrated parameters
+obtained from inertial motion units (IMU) placed on ice floes inside the MIZ.
+The results are compared with integrated parameters from the WAM-4 spectral
+wave model over a period of three days in the open ocean. We also compare our
+measurements outside and inside the MIZ with hindcast data from the new
+pan-Arctic WAM-3 model and the Wave Watch III model for the European Arctic,
+which both model wave attenuation in sea ice. A good agreement is found with
+WAM-4 and WW3 in zero up-crossing period and significant wave height outside
+the MIZ, where deviations are less than 23%. WAM-3 is on the other hand up to
+60% higher than observations. WW3 and WAM-3 are able to estimate the trends for
+significant wave height and zero up-crossing period inside the MIZ, although
+the discrepancies with respect to the observations were larger than in the open
+ocean. Wave damping by sea ice is investigated by looking at the spatial
+attenuation coefficients. Predicted attenuation coefficients are found to be
+72-83% smaller for WW3 and 3-64% larger for WAM-3 compared to observations.
+Hence, further model tuning is necessary to better estimate wave parameters in
+the ice.",2003.09472v3
+2020-09-24,Kinetic energy dissipation and fluctuations in strongly-damped heavy-ion collisions within the stochastic mean-field approach,"Background: Microscopic mean-field approaches have been successful in
+describing the most probable reaction outcomes in low-energy heavy-ion
+reactions. However, those approaches are known to severely underestimate
+dispersions of observables around the average values that has limited their
+applicability. Recently it has been shown that a quantal transport approach
+based on the stochastic mean-field (SMF) theory significantly improves the
+description, while its application has been limited so far to fragment mass and
+charge dispersions.
+  Purpose: In this work, we extend the quantal transport approach based on the
+SMF theory for relative kinetic energy dissipation and angular momentum
+transfer in low-energy heavy-ion reactions.
+  Results: As the first application of the proposed formalism, we consider the
+radial linear momentum dispersion, neglecting the coupling between radial and
+angular momenta. We analyze the total kinetic energy (TKE) distribution of
+binary reaction products in the $^{136}$Xe+$^{208}$Pb reaction at
+$E_\mathrm{c.m.}=526$ MeV and compare with experimental data. From time
+evolution of single-particle orbitals in TDHF, the radial diffusion coefficient
+is computed on a microscopic basis, while a phenomenological treatment is
+introduced for the radial friction coefficient. By solving the quantal
+diffusion equation for the radial linear momentum, the dispersion of the radial
+linear momentum is obtained, from which one can construct the TKE distribution.
+We find that the calculations provide a good description of the TKE
+distribution for large values of energy losses, TKEL $\gtrsim$ 150 MeV.
+However, the calculations underestimate the TKE distribution for smaller energy
+losses. Further studies are needed to improve the technical details of
+calculations.
+  (Shortened due to the word limit)",2009.11978v2
+2021-01-21,A Gauss-Seidel projection method with the minimal number of updates for stray field in micromagnetic simulations,"Magnetization dynamics in magnetic materials is often modeled by the
+Landau-Lifshitz equation, which is solved numerically in general. In
+micromagnetic simulations, the computational cost relies heavily on the
+time-marching scheme and the evaluation of stray field. Explicit marching
+schemes are efficient but suffer from severe stability constraints, while
+nonlinear systems of equations have to be solved in implicit schemes though
+they are unconditionally stable. A better compromise between stability and
+efficiency is the semi-implicit scheme, such as the Gauss-Seidel projection
+method (GSPM) and the second-order backward differentiation formula scheme
+(BDF2). At each marching step, GSPM solves several linear systems of equations
+with constant coefficients and updates the stray field several times, while
+BDF2 updates the stray field only once but solves a larger linear system of
+equations with variable coefficients and a nonsymmetric structure. In this
+work, we propose a new method, dubbed as GSPM-BDF2, by combing the advantages
+of both GSPM and BDF2. Like GSPM, this method is first-order accurate in time
+and second-order accurate in space, and is unconditionally stable with respect
+to the damping parameter. However, GSPM-BDF2 updates the stray field only once
+per time step, leading to an efficiency improvement of about $60\%$ than the
+state-of-the-art GSPM for micromagnetic simulations. For Standard Problem \#4
+and \#5 from National Institute of Standards and Technology, GSPM-BDF2 reduces
+the computational time over the popular software OOMMF by $82\%$ and $96\%$,
+respectively. Thus, the proposed method provides a more efficient choice for
+micromagnetic simulations.",2101.08574v1
+2022-07-06,Anisotropic Behavior of the Thermoelectric Power and the Thermal Conductivity in a Unidirectional Lateral Superlattice: A Typical Anisotropic System Exhibiting Two Distinct Nernst Coefficients,"We have calculated the thermoelectric conductivity tensor $\varepsilon_{ij}$
+and the thermal conductivity tensor $\lambda_{ij}$ of a unidirectional lateral
+superlattice (ULSL) ($i,j = x,y$, with the $x$-axis aligned to the principal
+axis of the ULSL), %, given as the first- and the second-order moments,
+employing based on the asymptotic analytic formulas of the electrical
+conductivity tensor $\sigma_{ij}$ in the literature valid at low magnetic
+fields where large numbers of Landau levels are occupied. With the resulting
+analytic expressions, we clarify the conditions for the Mott formula
+(Wiedemann-Franz law) to be applicable with high precision to
+$\varepsilon_{ij}$ ($\lambda_{ij}$). We further present plots of the
+commensurability oscillations $\delta\varepsilon_{ij}$, $\delta\lambda_{ij}$,
+$\delta\kappa_{ij}$, and $\delta S_{ij}$ in $\varepsilon_{ij}$, $\lambda_{ij}$,
+(an alternative, more standard definition of) the thermal conductivity tensor
+$\kappa_{ij}$, and the thermopower tensor $S_{ij}$, calculated using typical
+parameters for a ULSL fabricated from a GaAs/AlGaAs two-dimensional electron
+gas (2DEG). Notable features of the $\delta S_{ij}$ are (i) anisotropic
+behavior ($\delta S_{xx} \ne \delta S_{yy}$) and (ii) the dominance of the $xy$
+component over the other components ($|\delta S_{xy}| \gg |\delta S_{yx}|,
+|\delta S_{xx}|, |\delta S_{yy}|$). The latter clearly indicates that the two
+Nernst coefficients, $S_{xy}$ and $S_{yx}$, can be totally different from each
+other in an anisotropic system. Both (i) and (ii) are at variance with the
+previous theory and are attributable to the inclusion of a damping factor due
+to the small-angle scattering characteristic of GaAs/AlGaAs 2DEGs, which have
+not been taken into consideration in $\delta S_{ij}$ thus far.",2207.02367v3
+2022-07-13,Probing Bardeen-Kiselev black hole with cosmological constant caused by Einstein equations coupled with nonlinear electrodynamics using quasinormal modes and greybody bounds,"In this work, we investigate a static and spherically symmetric
+Bardeen-Kiselev black hole with cosmological constant which is a solution of
+the Einstein-non-linear Maxwell field equations along with a quintessential
+field. We compute the quasinormal frequencies for Bardeen-Kiselev black
+hole(BH) with cosmological constant due to electromagnetic and gravitational
+perturbations. By varying the BH parameters, we discuss the behaviour of both
+real and imaginary parts of the BH quasinormal frequencies and compare
+frequencies with Reissner-Nordstr\""om-de Sitter BH surrounded by quintessence
+(RN-dSQ). Interestingly, it shows that the response of Bardeen-Kiselev BH with
+cosmological constant and RN-dSQ under electromagnetic perturbations are
+different when the charge parameter $q$, the state parameter $w$ and the
+normalization factor $c$ are varied, but for the gravitational perturbations,
+the response of Bardeen-Kiselev BH with cosmological constant and RN-dSQ are
+different only when the charge parameter $q$ is varied. Therefore, compared
+with the gravitational perturbations, the electromagnetic perturbations can be
+used to understand nonlinear and linear electromagnetic fields in curved
+spacetime separately. Another interesting observation is that due to the
+presence of quintessence, the electromagnetic perturbations around the
+Bardeen-Kiselev BH with cosmological constant damps faster and oscillates
+slowly, and for the gravitational perturbations, the quasinormal mode decays
+slowly and oscillates slowly. We also study the reflection and transmission
+coefficients along with absorption cross section for the Bardeen-Kiselev BH
+with cosmological constant, it shows that the transmission coefficients will
+increase due to the presence of quintessence.",2207.05907v4
+2022-07-29,Global spherically symmetric solutions to degenerate compressible Navier-Stokes equations with large data and far field vacuum,"We consider the initial-boundary value problem (IBVP) for the isentropic
+compressible Navier-Stokes equations (\textbf{CNS}) in the domain exterior to a
+ball in $\mathbb R^d$ $(d=2\ \text{or} \ 3)$. When viscosity coefficients are
+given as a constant multiple of the mass density $\rho$, based on some analysis
+of the nonlinear structure of this system, we prove the global existence of the
+unique spherically symmetric classical solution for (large) initial data with
+spherical symmetry and far field vacuum in some inhomogeneous Sobolev spaces.
+Moreover, the solutions we obtained have the conserved total mass and finite
+total energy. $\rho$ keeps positive in the domain considered but decays to zero
+in the far field, which is consistent with the facts that the total mass is
+conserved, and \textbf{CNS} is a model of non-dilute fluids where $\rho$ is
+bounded away from the vacuum. To prove the existence, on the one hand, we
+consider a well-designed reformulated structure by introducing some new
+variables, which, actually, can transfer the degeneracies of the time evolution
+and the viscosity to the possible singularity of some special source terms. On
+the other hand, it is observed that, for the spherically symmetric flow, the
+radial projection of the so-called effective velocity $\boldsymbol{v} =U+\nabla
+\varphi(\rho)$ ($U$ is the velocity of the fluid, and $\varphi(\rho)$ is a
+function of $\rho$ defined via the shear viscosity coefficient $\mu(\rho)$:
+$\varphi'(\rho)=2\mu(\rho)/\rho^2$), verifies a damped transport equation which
+provides the possibility to obtain its upper bound. Then combined with the BD
+entropy estimates, one can obtain the required uniform a priori estimates of
+the solution. It is worth pointing out that the frame work on the
+well-posedness theory established here can be applied to the shallow water
+equations.",2207.14494v1
+2022-11-23,Lattice eddy simulation of turbulent flows,"Kolmogorov's (1941) theory of self-similarity implies the universality of
+small-scale eddies, and holds promise for a universal sub-grid scale model for
+large eddy simulation. The fact is the empirical coefficient of a typical
+sub-grid scale model varies from 0.1 to 0.2 in free turbulence and damps
+gradually to zero approaching the walls. This work has developed a Lattice Eddy
+Simulation method (LAES), in which the sole empirical coefficient is constant
+(Cs=0.08). LAES assumes the fluid properties are stored in the nodes of a
+typical CFD mesh, treats the nodes as lattices and makes analysis on one
+specific lattice, i. To be specific, LAES express the domain derivative on that
+lattice with the influence of nearby lattices. The lattices right next to i,
+which is named as i+, ""collide"" with i, imposing convective effects on i. The
+lattices right next to i+, which is named as i++, impose convective effects on
+i+ and indirectly influence i. The influence is actually turbulent diffusion.
+The derived governing equations of LAES look like the Navier-Stokes equations
+and reduce to filtered Naiver-Stokes equations with the Smagorinsky sub-grid
+scale model (Smagorinsky 1963) on meshes with isotropic cells. LAES yields
+accurate predictions of turbulent channel flows at Re=180, 395, and 590 on very
+coarse meshes and LAES with a constant Cs perform as well as the dynamic LES
+model (Germano et al. 1991) does. Thus, this work has provided strong evidence
+for Kolmogorov's theory of self-similarity.",2211.12810v1
+1996-06-07,Abundances at High Redshifts: the Chemical Enrichment History of Damped Lyman-alpha Galaxies,"Damped Lyman-alpha absorption systems found in the spectra of high redshift
+quasars are believed to trace the interstellar gas in high redshift galaxies.
+In this paper, we study the elemental abundances of C, N, O, Al, Si, S, Cr, Mn,
+Fe, Ni, and Zn in a sample of 14 damped Lyman-alpha systems using high quality
+echelle spectra of quasars obtained with the 10m Keck telescope. These
+abundances are combined with similar measurements in the literature in order to
+investigate the chemical evolution of damped Lyman-alpha galaxies in the
+redshift range 0.7<z<4.4. Among the things investigated are: the metallicity
+distribution of damped Lyman-alpha galaxy, its evolution with redshift (ie,
+age-metallicity relation), the relative abundance patterns of the heavy metals
+and implications for their nucleosynthetic origin, the effects of dust, the
+nature of the star formation process in damped Lyman-alpha galaxies, and the
+nature of damped Lyman-alpha galaxies themselves.",9606044v1
+1998-07-17,Chaotic scattering on surfaces and collisional damping of collective modes,"The damping of hot giant dipole resonances is investigated. The contribution
+of surface scattering is compared with the contribution from interparticle
+collisions. A unified response function is presented which includes surface
+damping as well as collisional damping. The surface damping enters the response
+via the Lyapunov exponent and the collisional damping via the relaxation time.
+The former is calculated for different shape deformations of quadrupole and
+octupole type. The surface as well as the collisional contribution each
+reproduce almost the experimental value, therefore we propose a proper
+weighting between both contributions related to their relative occurrence due
+to collision frequencies between particles and of particles with the surface.
+We find that for low and high temperatures the collisional contribution
+dominates whereas the surface damping is dominant around the temperatures
+$\sqrt{3}/2\pi$ of the centroid energy.",9807185v4
+2000-09-08,Probing High-Redshift Disks with Damped Lyman Alpha Systems,"Evidence is presented that the damped Lyman alpha absorption systems are the
+high-redshift (z > 3) progenitors of galaxy disks. I discuss kinematic evidence
+that the damped Lyman Alpha systems are rotating disks. I also discuss
+implications of the lack of metal-poor damped Lyman alpha systems with line
+width Delta v > 100 {\kms}. I then present new evidence stemming from
+correlations between element-abundance ratios and [Fe/H], which connects damped
+systems to the thick stellar disk of the Galaxy. I discuss the connections
+between damped Lyman alpha systems and Lyman break galaxies, and how [CII] 158
+micron emission from damped Lyman alpha systems discriminates among competing
+theories of galaxy formation. ~",0009126v1
+2006-09-10,Damping of Compressional MHD Waves In Quiescent Prominences and Prominence-Corona Transition Region (PCTR),"The effects of radiative losses due to Newtonian cooling and MHD turbulence
+have been considered to examine the spatial damping of linear compressional
+waves in quiescent prominences and prominence-corona transition region (PCTR).
+The radiative losses give acceptable damping lengths for the slow mode wave for
+the radiative relaxation time in the range (10-1000s). From prominence
+seismology, the values of opacity and turbulent kinematic viscosity have been
+inferred. It has been found that for a given value of radiative relaxation
+time, the high frequency slow mode waves are highly damped. We have also
+investigated the possible role of MHD turbulence in damping of MHD waves and
+found a turbulent viscosity can re-produce the observed damping time and
+damping length in prominences, especially in PCTR.",0609266v1
+1997-10-14,Damping of low-energy excitations of a trapped Bose condensate at finite temperatures,"We present the theory of damping of low-energy excitations of a trapped Bose
+condensate at finite temperatures, where the damping is provided by the
+interaction of these excitations with the thermal excitations. We emphasize the
+key role of stochastization in the behavior of the thermal excitations for
+damping in non-spherical traps. The damping rates of the lowest excitations,
+following from our theory, are in fair agreement with the data of recent JILA
+and MIT experiments. The damping of quasiclassical excitations is determined by
+the condensate boundary region, and the result for the damping rate is
+drastically different from that in a spatially homogeneous gas.",9710128v3
+2001-12-09,Soliton dynamics in damped and forced Boussinesq equations,"We investigate the dynamics of a lattice soliton on a monatomic chain in the
+presence of damping and external forces. We consider Stokes and hydrodynamical
+damping. In the quasi-continuum limit the discrete system leads to a damped and
+forced Boussinesq equation. By using a multiple-scale perturbation expansion up
+to second order in the framework of the quasi-continuum approach we derive a
+general expression for the first-order velocity correction which improves
+previous results. We compare the soliton position and shape predicted by the
+theory with simulations carried out on the level of the monatomic chain system
+as well as on the level of the quasi-continuum limit system. For this purpose
+we restrict ourselves to specific examples, namely potentials with cubic and
+quartic anharmonicities as well as the truncated Morse potential, without
+taking into account external forces. For both types of damping we find a good
+agreement with the numerical simulations both for the soliton position and for
+the tail which appears at the rear of the soliton. Moreover we clarify why the
+quasi-continuum approximation is better in the hydrodynamical damping case than
+in the Stokes damping case.",0112148v1
+2006-04-17,The Highly Damped Quasinormal Modes of $d$-dimensional Reissner-Nordstrom Black Holes in the Small Charge Limit,"We analyze in detail the highly damped quasinormal modes of $d$-dimensional
+Reissner-Nordstr$\ddot{\rm{o}}$m black holes with small charge, paying
+particular attention to the large but finite damping limit in which the
+Schwarzschild results should be valid. In the infinite damping limit, we
+confirm using different methods the results obtained previously in the
+literature for higher dimensional Reissner-Nordstr$\ddot{\rm{o}}$m black holes.
+Using a combination of analytic and numerical techniques we also calculate the
+transition of the real part of the quasinormal mode frequency from the
+Reissner-Nordstr$\ddot{\rm{o}}$m value for very large damping to the
+Schwarzschild value of $\ln(3) T_{bh}$ for intermediate damping. The real
+frequency does not interpolate smoothly between the two values. Instead there
+is a critical value of the damping at which the topology of the
+Stokes/anti-Stokes lines change, and the real part of the quasinormal mode
+frequency dips to zero.",0604073v2
+2005-02-16,Damping signatures in future neutrino oscillation experiments,"We discuss the phenomenology of damping signatures in the neutrino
+oscillation probabilities, where either the oscillating terms or the
+probabilities can be damped. This approach is a possibility for tests of
+non-oscillation effects in future neutrino oscillation experiments, where we
+mainly focus on reactor and long-baseline experiments. We extensively motivate
+different damping signatures due to small corrections by neutrino decoherence,
+neutrino decay, oscillations into sterile neutrinos, or other mechanisms, and
+classify these signatures according to their energy (spectral) dependencies. We
+demonstrate, at the example of short baseline reactor experiments, that damping
+can severely alter the interpretation of results, e.g., it could fake a value
+of $\sin(2\theta_{13})$ smaller than the one provided by Nature. In addition,
+we demonstrate how a neutrino factory could constrain different damping models
+with emphasis on how these different models could be distinguished, i.e., how
+easily the actual non-oscillation effects could be identified. We find that the
+damping models cluster in different categories, which can be much better
+distinguished from each other than models within the same cluster.",0502147v2
+1997-07-23,Riccati parameter modes from Newtonian free damping motion by supersymmetry,"We determine the class of damped modes \tilde{y} which are related to the
+common free damping modes y by supersymmetry. They are obtained by employing
+the factorization of Newton's differential equation of motion for the free
+damped oscillator by means of the general solution of the corresponding Riccati
+equation together with Witten's method of constructing the supersymmetric
+partner operator. This procedure leads to one-parameter families of (transient)
+modes for each of the three types of free damping, corresponding to a
+particular type of %time-dependent angular frequency. %time-dependent,
+antirestoring acceleration (adding up to the usual Hooke restoring
+acceleration) of the form a(t)=\frac{2\gamma ^2}{(\gamma t+1)^{2}}\tilde{y},
+where \gamma is the family parameter that has been chosen as the inverse of the
+Riccati integration constant. In supersymmetric terms, they represent all those
+one Riccati parameter damping modes having the same Newtonian free damping
+partner mode",9707019v4
+2000-08-22,Local and Fundamental Mode Coupler Damping of the Transverse Wakefield in RDDS1 Linacs,"In damping the wakefield generated by an electron beam traversing several
+thousand X-band linacs in the NLC we utilise a Gaussian frequency distribution
+of dipole modes to force the modes to deconstructively interfere, supplemented
+with moderate damping achieved by coupling these modes to four attached
+manifolds. Most of these modes are adequately damped by the manifolds. However,
+the modes towards the high frequency end of the lower dipole band are not
+adequately damped because the last few cells are, due to mechanical fabrication
+requirements, not coupled to the manifolds. To mitigate this problem in the
+present RDDS1 design, the output coupler for the accelerating mode has been
+designed so as to also couple out those dipole modes which reach the output
+coupler cell. In order to couple out both dipole mode polarizations, the output
+coupler has four ports. We also report on the results of a study of the
+benefits which can be achieved by supplementing manifold damping with local
+damping for a limited number of cells at the downstream end of the structure.",0008211v1
+2007-10-25,Damping of Condensate Oscillation of a Trapped Bose Gas in a One-Dimensional Optical Lattice at Finite Temperatures,"We study damping of a dipole oscillation in a Bose-Condensed gas in a
+combined cigar-shaped harmonic trap and one-dimensional (1D) optical lattice
+potential at finite temperatures. In order to include the effect of thermal
+excitations in the radial direction, we derive a quasi-1D model of the
+Gross-Pitaeavskii equation and the Bogoliubov equations. We use the Popov
+approximation to calculate the temperature dependence of the condensate
+fraction with varying lattice depth. We then calculate the Landau damping rate
+of a dipole oscillation as a function of the lattice depth and temperature. The
+damping rate increases with increasing lattice depth, which is consistent with
+experimental observations. The magnitude of the damping rate is in reasonable
+agreement with experimental data. We also find that the damping rate has a
+strong temperature dependence, showing a sharp increase with increasing
+temperature. Finally, we emphasize the importance of the radial thermal
+excitations in both equilibrium properties and the Landau damping.",0710.4610v1
+2008-01-03,Spin orbit precession damping in transition metal ferromagnets,"We provide a simple explanation, based on an effective field, for the
+precession damping rate due to the spin-orbit interaction. Previous effective
+field treatments of spin-orbit damping include only variations of the state
+energies with respect to the magnetization direction, an effect referred to as
+the breathing Fermi surface. Treating the interaction of the rotating spins
+with the orbits as a perturbation, we include also changes in the state
+populations in the effective field. In order to investigate the quantitative
+differences between the damping rates of iron, cobalt, and nickel, we compute
+the dependence of the damping rate on the density of states and the spin-orbit
+parameter. There is a strong correlation between the density of states and the
+damping rate. The intraband terms of the damping rate depend on the spin-orbit
+parameter cubed while the interband terms are proportional to the spin-orbit
+parameter squared. However, the spectrum of band gaps is also an important
+quantity and does not appear to depend in a simple way on material parameters.",0801.0549v1
+2009-02-03,Damping of filament thread oscillations: effect of the slow continuum,"Transverse oscillations of small amplitude are commonly seen in
+high-resolution observations of filament threads, i.e. the fine-structures of
+solar filaments/prominences, and are typically damped in a few periods. Kink
+wave modes supported by the thread body offer a consistent explanation of these
+observed oscillations. Among the proposed mechanisms to explain the kink mode
+damping, resonant absorption in the Alfven continuum seems to be the most
+efficient as it produces damping times of about 3 periods. However, for a
+nonzero-beta plasma and typical prominence conditions, the kink mode is also
+resonantly coupled to slow (or cusp) continuum modes, which could further
+reduce the damping time. In this Letter, we explore for the first time both
+analytically and numerically the effect of the slow continuum on the damping of
+transverse thread oscillations. The thread model is composed of a homogeneous
+and straight cylindrical plasma, an inhomogeneous transitional layer, and the
+homogeneous coronal plasma. We find that the damping of the kink mode due to
+the slow resonance is much less efficient than that due to the Alfven
+resonance.",0902.0572v2
+2010-11-23,Magnetohydrodynamic kink waves in two-dimensional non-uniform prominence threads,"We analyse the oscillatory properties of resonantly damped transverse kink
+oscillations in two-dimensional prominence threads. The fine structures are
+modelled as cylindrically symmetric magnetic flux tubes with a dense central
+part with prominence plasma properties and an evacuated part, both surrounded
+by coronal plasma. The equilibrium density is allowed to vary non-uniformly in
+both the transverse and the longitudinal directions.We examine the influence of
+longitudinal density structuring on periods, damping times, and damping rates
+for transverse kink modes computed by numerically solving the linear resistive
+magnetohydrodynamic (MHD) equations. The relevant parameters are the length of
+the thread and the density in the evacuated part of the tube, two quantities
+that are difficult to directly estimate from observations. We find that both of
+them strongly influence the oscillatory periods and damping times, and to a
+lesser extent the damping ratios. The analysis of the spatial distribution of
+perturbations and of the energy flux into the resonances allows us to explain
+the obtained damping times. Implications for prominence seismology, the physics
+of resonantly damped kink modes in two-dimensional magnetic flux tubes, and the
+heating of prominence plasmas are discussed.",1011.5175v2
+2011-04-04,Plasmonic abilities of gold and silver spherical nanoantennas in terms of size dependent multipolar resonance frequencies and plasmon damping rates,"Absorbing and emitting optical properties of a spherical plasmonic
+nanoantenna are described in terms of the size dependent resonance frequencies
+and damping rates of the multipolar surface plasmons (SP). We provide the
+plasmon size characteristics for gold and silver spherical particles up to the
+large size retardation regime where the plasmon radiative damping is
+significant. We underline the role of the radiation damping in comparison with
+the energy dissipation damping in formation of receiving and transmitting
+properties of a plasmonic particle. The size dependence of both: the multipolar
+SP resonance frequencies and corresponding damping rates can be a convenient
+tool in tailoring the characteristics of plasmonic nanoantennas for given
+application. Such characteristics enable to control an operation frequency of a
+plasmonic nanoantenna and to change the operation range from the spectrally
+broad to spectrally narrow and vice versa. It is also possible to switch
+between particle receiving (enhanced absorption) and emitting (enhanced
+scattering) abilities. Changing the polarization geometry of observation it is
+possible to effectively separate the dipole and the quadrupole plasmon
+radiation from all the non-plasmonic contributions to the scattered light.
+Keywords: surface plasmon (SP) resonance, plasmon damping rates, multipolar
+plasmon",1104.0565v1
+2011-11-16,Three-player quantum Kolkata restaurant problem under decoherence,"Effect of quantum decoherence in a three-player quantum Kolkata restaurant
+problem is investigated using tripartite entangled qutrit states. Amplitude
+damping, depolarizing, phase damping, trit-phase flip and phase flip channels
+are considered to analyze the behaviour of players payoffs. It is seen that
+Alice's payoff is heavily influenced by the amplitude damping channel as
+compared to the depolarizing and flipping channels. However, for higher level
+of decoherence, Alice's payoff is strongly affected by depolarizing noise.
+Whereas the behaviour of phase damping channel is symmetrical around 50 %
+decoherence. It is also seen that for maximum decoherence (p=1), the influence
+of amplitude damping channel dominates over depolarizing and flipping channels.
+Whereas, phase damping channel has no effect on the Alice's payoff. Therefore,
+the problem becomes noiseless one at maximum decoherence in case of phase
+damping channel. Furthermore, the Nash equilibrium of the problem does not
+change under decoherence.",1111.3913v2
+2012-07-27,The effect of non-uniform damping on flutter in axial flow and energy harvesting strategies,"The problem of energy harvesting from flutter instabilities in flexible
+slender structures in axial flows is considered. In a recent study, we used a
+reduced order theoretical model of such a system to demonstrate the feasibility
+for harvesting energy from these structures. Following this preliminary study,
+we now consider a continuous fluid-structure system. Energy harvesting is
+modelled as strain-based damping and the slender structure under investigation
+lies in a moderate fluid loading range, for which {the flexible structure} may
+be destabilised by damping. The key goal of this work is to {analyse the effect
+of damping distribution and intensity on the amount of energy harvested by the
+system}. The numerical results {indeed} suggest that non-uniform damping
+distributions may significantly improve the power harvesting capacity of the
+system. For low damping levels, clustered dampers at the position of peak
+curvature are shown to be optimal. Conversely for higher damping, harvesters
+distributed over the whole structure are more effective.",1207.6484v1
+2012-11-20,Damping rates of surface plasmons for particles of size from nano- to micrometers; reduction of the nonradiative decay,"Damping rates of multipolar, localized surface plasmons (SP) of gold and
+silver nanospheres of radii up to $1000nm$ were found with the tools of
+classical electrodynamics. The significant increase in damping rates followed
+by noteworthy decrease for larger particles takes place along with substantial
+red-shift of plasmon resonance frequencies as a function of particle size. We
+also introduced interface damping into our modeling, which substantially
+modifies the plasmon damping rates of smaller particles. We demonstrate
+unexpected reduction of the multipolar SP damping rates in certain size ranges.
+This effect can be explained by the suppression of the nonradiative decay
+channel as a result of the lost competition with the radiative channel. We show
+that experimental dipole damping rates [H. Baida, et al., Nano Lett. 9(10)
+(2009) 3463, and C. S\""onnichsen, et al., Phys. Rev. Lett. 88 (2002) 077402],
+and the resulting resonance quality factors can be described in a consistent
+and straightforward way within our modeling extended to particle sizes still
+unavailable experimentally.",1211.4781v1
+2013-10-23,Landau damping in a collisionless dipolar Bose gas,"We present a theory for the Landau damping of low energy quasi-particles in a
+collisionless, quasi-2D dipolar Bose gas and produce expressions for the
+damping rate in uniform and non-uniform systems. Using simple energy-momentum
+conservation arguments, we show that in the homogeneous system, the nature of
+the low energy dispersion in a dipolar Bose gas severely inhibits Landau
+damping of long wave-length excitations. For a gas with contact and dipolar
+interactions, the damping rate for phonons tends to decrease with increasing
+dipolar interactions; for strong dipole-dipole interactions, phonons are
+virtually undamped over a broad range of temperature. The damping rate for
+maxon-roton excitations is found to be significantly larger than the damping
+rate for phonons.",1310.6386v1
+2014-01-15,Damping of Terahertz Plasmons in Graphene Coupled with Surface Plasmons in Heavily-Doped Substrate,"Coupling of plasmons in graphene at terahert (THz) frequencies with surface
+plasmons in a heavily-doped substrate is studied theoretically. We reveal that
+a huge scattering rate may completely damp out the plasmons, so that proper
+choices of material and geometrical parameters are essential to suppress the
+coupling effect and to obtain the minimum damping rate in graphene. Even with
+the doping concentration 10^{19} - 10^{20} cm^{-3} and the thickness of the
+dielectric layer between graphene and the substrate 100 nm, which are typical
+values in real graphene samples with a heavily-doped substrate, the increase in
+the damping rate is not negligible in comparison with the
+acoustic-phonon-limited damping rate. Dependence of the damping rate on
+wavenumber, thicknesses of graphene-to-substrate and gate-to-graphene
+separation, substrate doping concentration, and dielectric constants of
+surrounding materials are investigated. It is shown that the damping rate can
+be much reduced by the gate screening, which suppresses the field spread of the
+graphene plasmons into the substrate.",1401.3396v1
+2014-11-28,Non-equilibrium thermodynamics of damped Timoshenko and damped Bresse systems,"In this paper, we cast damped Timoshenko and damped Bresse systems into a
+general framework for non-equilibrium thermodynamics, namely the GENERIC
+(General Equation for Non-Equilibrium Reversible-Irreversible Coupling)
+framework. The main ingredients of GENERIC consist of five building blocks: a
+state space, a Poisson operator, a dissipative operator, an energy functional,
+and an entropy functional. The GENERIC formulation of damped Timoshenko and
+damped Bresse systems brings several benefits. First, it provides alternative
+ways to derive thermodynamically consistent models of these systems by
+construct- ing building blocks instead of invoking conservation laws and
+constitutive relations. Second, it reveals clear physical and geometrical
+structures of these systems, e.g., the role of the energy and the entropy as
+the driving forces for the reversible and irreversible dynamics respectively.
+Third, it allows us to introduce a new GENERIC model for damped Timoshenko
+systems that is not existing in the literature.",1412.0038v2
+2014-12-08,Bi-$\cal{PT}$ symmetry in nonlinearly damped dynamical systems and tailoring $\cal{PT}$ regions with position dependent loss-gain profiles,"We investigate the remarkable role of position dependent damping in
+determining the parametric regions of symmetry breaking in nonlinear
+$\cal{PT}$-symmetric systems. We illustrate the nature of $\cal{PT}$-symmetry
+preservation and breaking with reference to a remarkable integrable scalar
+nonlinear system. In the two dimensional cases of such position dependent
+damped systems, we unveil the existence of a class of novel
+bi-$\cal{PT}$-symmetric systems which have two fold $\cal{PT}$ symmetries. We
+analyze the dynamics of these systems and show how symmetry breaking occurs,
+that is whether the symmetry breaking of the two $\cal{PT}$ symmetries occurs
+in pair or occurs one by one. The addition of linear damping in these
+nonlinearly damped systems induces competition between the two types of
+damping. This competition results in a $\cal{PT}$ phase transition in which the
+$\cal{PT}$ symmetry is broken for lower loss/gain strength and is restored by
+increasing the loss/gain strength. We also show that by properly designing the
+form of the position dependent damping, we can tailor the $\cal{PT}$-symmetric
+regions of the system.",1412.2574v3
+2015-09-04,Damped transverse oscillations of interacting coronal loops,"Damped transverse oscillations of magnetic loops are routinely observed in
+the solar corona. This phenomenon is interpreted as standing kink
+magnetohydrodynamic waves, which are damped by resonant absorption owing to
+plasma inhomogeneity across the magnetic field. The periods and damping times
+of these oscillations can be used to probe the physical conditions of the
+coronal medium. Some observations suggest that interaction between neighboring
+oscillating loops in an active region may be important and can modify the
+properties of the oscillations compared to those of an isolated loop. Here we
+theoretically investigate resonantly damped transverse oscillations of
+interacting non-uniform coronal loops. We provide a semi-analytic method, based
+on the T-matrix theory of scattering, to compute the frequencies and damping
+rates of collective oscillations of an arbitrary configuration of parallel
+cylindrical loops. The effect of resonant damping is included in the T-matrix
+scheme in the thin boundary approximation. Analytic and numerical results in
+the specific case of two interacting loops are given as an application.",1509.01487v1
+2015-09-14,Beliaev damping in quasi-2D dipolar condensates,"We study the effects of quasiparticle interactions in a quasi-two dimensional
+(quasi-2D), zero-temperature Bose-Einstein condensate of dipolar atoms, which
+can exhibit a roton-maxon feature in its quasiparticle spectrum. Our focus is
+the Beliaev damping process, in which a quasiparticle collides with the
+condensate and resonantly decays into a pair of quasiparticles. Remarkably, the
+rate for this process exhibits a highly non-trivial dependence on the
+quasiparticle momentum and the dipolar interaction strength. For weak
+interactions, the low energy phonons experience no damping, and the higher
+energy quasiparticles undergo anomalously weak damping. In contrast, the
+Beliaev damping rates become anomalously large for stronger dipolar
+interactions, as rotons become energetically accessible as final states.
+Further, we find a qualitative anisotropy in the damping rates when the dipoles
+are tilted off the axis of symmetry. Our study reveals the unconventional
+nature of Beliaev damping in dipolar condensates, and has important
+implications for ongoing studies of equilibrium and non-equilibrium dynamics in
+these systems.",1509.04217v1
+2015-12-08,Thermal energies of classical and quantum damped oscillators coupled to reservoirs,"We consider the global thermal state of classical and quantum harmonic
+oscillators that interact with a reservoir. Ohmic damping of the oscillator can
+be exactly treated with a 1D scalar field reservoir, whereas general non-Ohmic
+damping is conveniently treated with a continuum reservoir of harmonic
+oscillators. Using the diagonalized Hamiltonian of the total system, we
+calculate a number of thermodynamic quantities for the damped oscillator: the
+mean force internal energy, mean force free energy, and another internal energy
+based on the free-oscillator Hamiltonian. The classical mean force energy is
+equal to that of a free oscillator, for both Ohmic and non-Ohmic damping and no
+matter how strong the coupling to the reservoir. In contrast, the quantum mean
+force energy depends on the details of the damping and diverges for strictly
+Ohmic damping. These results give additional insight into the steady-state
+thermodynamics of open systems with arbitrarily strong coupling to a reservoir,
+complementing results for energies derived within dynamical approaches (e.g.
+master equations) in the weak-coupling regime.",1512.02551v2
+2016-10-10,A Five-Freedom Active Damping and Alignment Device Used in the Joule Balance,"Damping devices are necessary for suppressing the undesired coil motions in
+the watt/joule balance. In this paper, an active electromagnetic damping
+device, located outside the main magnet, is introduced in the joule balance
+project. The presented damping device can be used in both dynamic and static
+measurement modes. With the feedback from a detection system, five degrees of
+freedom of the coil, i.e. the horizontal displacement $x$, $y$ and the rotation
+angles $\theta_x$, $\theta_y$, $\theta_z$, can be controlled by the active
+damping device. Hence, two functions, i.e. suppressing the undesired coil
+motions and reducing the misalignment error, can be realized with this active
+damping device. The principle, construction and performance of the proposed
+active damping device are presented.",1610.02799v1
+2017-10-10,A four-field gyrofluid model with neoclassical effects for the study of the rotation velocity of magnetic islands in tokamaks,"A four-field system of equations which includes the neoclassical flow damping
+effects and the lowest-order finite-Larmor-radius (FLR) corrections is deduced
+from a system of gyrofluid equations. The FLR corrections to the poloidal flow
+damping are calculated by solving a simplified version of the gyrokinetic
+equation. This system of equations is applied to the study of a chain of freely
+rotating magnetic islands in a tokamak, resulting from the nonlinear evolution
+of a resistive tearing mode, to determine the islands rotation velocity
+consistently with the fields radial profiles close to the resonant surface. The
+island rotation velocity is determined by imposing the torque-balance
+condition. The equations thus deduced are applied to the study of two different
+collisional regimes, namely the weak-damping regime and the intermediate
+damping regime. The equations reduce, in the weak damping regime, to a form
+already obtained in previous works, while an additional term, containing the
+lowest order FLR corrections to the poloidal flow damping, appears in the
+intermediate damping regime. The numerical integration of the final system of
+equations permits to determine the dependence of the island rotation velocity
+on the plasma collisionality and the islands width compared to the ion Larmor
+radius.",1710.03585v1
+2017-12-04,Resonance oscillation of a damped driven simple pendulum,"The resonance characteristics of a driven damped harmonic oscillator are well
+known. Unlike harmonic oscillators which are guided by parabolic potentials, a
+simple pendulum oscillates under sinusoidal potentials. The problem of an
+undamped pendulum has been investigated to a great extent. However, the
+resonance characteristics of a driven damped pendulum have not been re- ported
+so far due to the difficulty in solving the problem analytically. In the
+present work we report the resonance characteristics of a driven damped
+pendulum calculated numerically. The results are compared with the resonance
+characteristics of a damped driven harmonic oscillator. The work can be of
+pedagogic interest too as it reveals the richness of driven damped motion of a
+simple pendulum in comparison to and how strikingly it differs from the motion
+of a driven damped harmonic oscillator. We confine our work only to the
+nonchaotic regime of pendulum motion.",1712.01032v1
+2018-01-17,On Global Existence and Blow-up for Damped Stochastic Nonlinear Schrödinger Equation,"In this paper, we consider the well-posedness of the weakly damped stochastic
+nonlinear Schr\""odinger(NLS) equation driven by multiplicative noise. First, we
+show the global existence of the unique solution for the damped stochastic NLS
+equation in critical case. Meanwhile, the exponential integrability of the
+solution is proved, which implies the continuous dependence on the initial
+data. Then, we analyze the effect of the damped term and noise on the blow-up
+phenomenon. By modifying the associated energy, momentum and variance identity,
+we deduce a sharp blow-up condition for damped stochastic NLS equation in
+supercritical case. Moreover, we show that when the damped effect is large
+enough, the damped effect can prevent the blow-up of the solution with high
+probability.",1801.05630v1
+2018-03-29,Giant resonant nonlinear damping in nanoscale ferromagnets,"Magnetic damping is a key metric for emerging technologies based on magnetic
+nanoparticles, such as spin torque memory and high-resolution biomagnetic
+imaging. Despite its importance, understanding of magnetic dissipation in
+nanoscale ferromagnets remains elusive, and the damping is often treated as a
+phenomenological constant. Here we report the discovery of a giant
+frequency-dependent nonlinear damping that strongly alters the response of a
+nanoscale ferromagnet to spin torque and microwave magnetic field. This novel
+damping mechanism originates from three-magnon scattering that is strongly
+enhanced by geometric confinement of magnons in the nanomagnet. We show that
+the giant nonlinear damping can invert the effect of spin torque on a
+nanomagnet leading to a surprising current-induced enhancement of damping by an
+antidamping torque. Our work advances understanding of magnetic dynamics in
+nanoscale ferromagnets and spin torque devices.",1803.10925v1
+2019-03-01,Comprehensive Study of Neutrino-Dark Matter Mixed Damping,"Mixed damping is a physical effect that occurs when a heavy species is
+coupled to a relativistic fluid which is itself free streaming. As a cross-case
+between collisional damping and free-streaming, it is crucial in the context of
+neutrino-dark matter interactions. In this work, we establish the parameter
+space relevant for mixed damping, and we derive an analytical approximation for
+the evolution of dark matter perturbations in the mixed damping regime to
+illustrate the physical processes responsible for the suppression of
+cosmological perturbations. Although extended Boltzmann codes implementing
+neutrino-dark matter scattering terms automatically include mixed damping, this
+effect has not been systematically studied. In order to obtain reliable
+numerical results, it is mandatory to reconsider several aspects of
+neutrino-dark matter interactions, such as the initial conditions, the
+ultra-relativistic fluid approximation and high order multiple moments in the
+neutrino distribution. Such a precise treatment ensures the correct assessment
+of the relevance of mixed damping in neutrino-dark matter interactions.",1903.00540v2
+2019-08-04,Efficient spin excitation via ultrafast damping-like torques in antiferromagnets,"Damping effects form the core of many emerging concepts for high-speed
+spintronic applications. Important characteristics such as device switching
+times and magnetic domain-wall velocities depend critically on the damping
+rate. While the implications of spin damping for relaxation processes are
+intensively studied, damping effects during impulsive spin excitations are
+assumed to be negligible because of the shortness of the excitation process.
+Herein, we show that, unlike in ferromagnets, ultrafast damping plays a crucial
+role in antiferromagnets because of their strongly elliptical spin precession.
+In time-resolved measurements, we find that ultrafast damping results in an
+immediate spin canting along the short precession axis. The interplay between
+antiferromagnetic exchange and magnetic anisotropy amplifies this canting by
+several orders of magnitude towards large-amplitude modulations of the
+antiferromagnetic order parameter. This leverage effect discloses a highly
+efficient route towards the ultrafast manipulation of magnetism in
+antiferromagnetic spintronics.",1908.01359v3
+2019-10-31,Gyrokinetic investigation of the damping channels of Alfvén modes in ASDEX Upgrade,"The linear destabilization and nonlinear saturation of energetic-particle
+driven Alfv\'enic instabilities in tokamaks strongly depend on the damping
+channels. In this work, the collisionless damping mechanisms of Alfv\'enic
+modes are investigated within a gyrokinetic framework, by means of global
+simulations with the particle-in-cell code ORB5, and compared with the
+eigenvalue code LIGKA and reduced models. In particular, the continuum damping
+and the Landau damping (of ions and electrons) are considered. The electron
+Landau damping is found to be dominant on the ion Landau damping for
+experimentally relevant cases. As an application, the linear and nonlinear
+dynamics of toroidicity induced Alfv\'en eigenmodes and energetic-particle
+driven modes in ASDEX Upgrade is investigated theoretically and compared with
+experimental measurements.",1910.14489v1
+2020-12-27,Quantum speed limit time in relativistic frame,"We investigate the roles of the relativistic effect on the speed of evolution
+of a quantum system coupled with amplitude damping channels. We find that the
+relativistic effect speed-up the quantum evolution to a uniform evolution speed
+of open quantum systems for the damping parameter $p_{\tau}\lesssim
+p_{\tau_{c0}}.$ Moreover, we point out a non-monotonic behavior of the quantum
+speed limit time (QSLT) with acceleration in the damping limit
+$p_{\tau_{c0}}\lesssim p_{\tau}\lesssim p_{\tau_{c1}},$ where the relativistic
+effect first speed-up and then slow down the quantum evolution process of the
+damped system. For the damping strength $p_{\tau_{c1}}\lesssim p_{\tau}$, we
+observe a monotonic increasing behavior of QSLT, leads to slow down the quantum
+evolution of the damped system. In addition, we examine the roles of the
+relativistic effect on the speed limit time for a system coupled with the phase
+damping channels.",2012.13859v2
+2021-06-23,Regularization of central forces with damping in two and three-dimensions,"Regularization of damped motion under central forces in two and
+three-dimensions are investigated and equivalent, undamped systems are
+obtained. The dynamics of a particle moving in $\frac{1}{r}$ potential and
+subjected to a damping force is shown to be regularized a la Levi-Civita. We
+then generalize this regularization mapping to the case of damped motion in the
+potential $r^{-\frac{2N}{N+1}}$. Further equation of motion of a damped Kepler
+motion in 3-dimensions is mapped to an oscillator with inverted sextic
+potential and couplings, in 4-dimensions using Kustaanheimo-Stiefel
+regularization method. It is shown that the strength of the sextic potential is
+given by the damping co-efficient of the Kepler motion. Using homogeneous
+Hamiltonian formalism, we establish the mapping between the Hamiltonian of
+these two models. Both in 2 and 3-dimensions, we show that the regularized
+equation is non-linear, in contrast to undamped cases. Mapping of a particle
+moving in a harmonic potential subjected to damping to an undamped system with
+shifted frequency is then derived using Bohlin-Sudman transformation.",2106.12134v1
+2021-07-06,Theory of vibrators with variable-order fractional forces,"In this paper, we present a theory of six classes of vibrators with
+variable-order fractional forces of inertia, damping, and restoration. The
+novelty and contributions of the present theory are reflected in six aspects.
+1) Equivalent motion equations of those variable-order fractional vibrators are
+proposed. 2) The analytical expressions of the effective mass, damping, and
+stiffness of those variable-order fractional vibrators are presented. 3) The
+asymptotic properties of the effective mass, damping, and stiffness of a class
+of variable-order fractional vibrators are given. 4) The restricted effective
+parameters (damping ratio, damping free natural frequency, damped natural
+frequency, frequency ratio) of the variable-order fractional vibrators are put
+forward. 5) We bring forward the analytical representations of the free
+responses, the impulse responses, and the frequency transfer functions of those
+variable-order fractional vibrators. 6) We propose a solution to an open
+problem of how to mathematically explain the Rayleigh damping assumption based
+on the present theory of variable-order fractional vibrations.",2107.02340v2
+2021-08-15,Exponential stability of a damped beam-string-beam transmission problem,"We consider a beam-string-beam transmission problem, where two structurally
+damped or undamped beams are coupled with a frictionally damped string by
+transmission conditions. We show that for this type of structure, the
+dissipation produced by the frictional part is strong enough to produce
+exponential decay of the solution no matter how small is its size: for the
+exponential stability in the damped-damped-damped situation we use energy
+method and in the undamped-damped-undamped situation we use a frequency domain
+method from the semigroups theory, which combines a contradiction argument with
+the multiplier technique to carry out a special analysis for the resolvent.
+Additionally, we show that the solution first defined by the weak formulation,
+in fact, has higher Sobolev space regularity.",2108.06749v1
+2021-09-10,Fourth-order dynamics of the damped harmonic oscillator,"It is shown that the classical damped harmonic oscillator belongs to the
+family of fourth-order Pais-Uhlenbeck oscillators. It follows that the
+solutions to the damped harmonic oscillator equation make the Pais-Uhlenbeck
+action stationary. Two systematic approaches are given for deriving the
+Pais-Uhlenbeck action from the damped harmonic oscillator equation, and it may
+be possible to use these methods to identify stationary action principles for
+other dissipative systems which do not conform to Hamilton's principle. It is
+also shown that for every damped harmonic oscillator $x$, there exists a
+two-parameter family of dual oscillators $y$ satisfying the Pais-Uhlenbeck
+equation. The damped harmonic oscillator and any of its duals can be
+interpreted as a system of two coupled oscillators with atypical spring
+stiffnesses (not necessarily positive and real-valued). For overdamped systems,
+the resulting coupled oscillators should be physically achievable and may have
+engineering applications. Finally, a new physical interpretation is given for
+the optimal damping ratio $\zeta=1/\sqrt{2}$ in control theory.",2109.06034v1
+2022-01-13,Damping of Alfvén waves in MHD turbulence and implications for cosmic ray streaming instability and galactic winds,"Alfv\'{e}nic component of MHD turbulence damps Alfv\'{e}nic waves. The
+consequences of this effect are important for many processes, from cosmic ray
+(CR) propagation to launching outflows and winds in galaxies and other
+magnetized systems. We discuss the differences in the damping of the streaming
+instability by turbulence and the damping of a plane parallel wave. The former
+takes place in the system of reference aligned with the local direction of
+magnetic field along which CRs stream. The latter is in the reference frame of
+the mean magnetic field and traditionally considered in plasma studies. We also
+compare the turbulent damping of streaming instability with ion-neutral
+collisional damping, which becomes the dominant damping effect at a
+sufficiently low ionization fraction. Numerical testing and astrophysical
+implications are also discussed.",2201.05168v1
+2022-03-14,Investigation of nonlinear squeeze-film damping involving rarefied gas effect in micro-electro-mechanical-systems,"In this paper, the nonlinear squeeze-film damping (SFD) involving rarefied
+gas effect in the micro-electro-mechanical-systems (MEMS) is investigated.
+Considering the motion of structures (beam, cantilever, and membrane) in MEMS,
+the dynamic response of structure will be influenced largely by the
+squeeze-film damping. In the traditional model, a viscous damping assumption
+that damping force is linear with moving velocity is used. As the nonlinear
+damping phenomenon is observed for a micro-structure oscillating with a
+high-velocity, this assumption is invalid and will generates error result for
+predicting the response of micro-structure. In addition, due to the small size
+of device and the low pressure of encapsulation, the gas in MEMS usually is
+rarefied gas. Therefore, to correctly predict the damping force, the rarefied
+gas effect must be considered. To study the nonlinear SFD phenomenon involving
+the rarefied gas effect, a kinetic method, namely discrete unified gas kinetic
+scheme (DUGKS), is introduced. And based on DUGKS, two solving methods, a
+traditional decoupled method (Eulerian scheme) and a coupled framework
+(arbitrary Lagrangian-Eulerian scheme), are adopted. With these two methods,
+two basic motion forms, linear (perpendicular) and tilting motions of a rigid
+micro-beam, are studied with forced and free oscillations.",2203.06902v1
+2022-05-21,Noether symmetries and first integrals of damped harmonic oscillator,"Noether theorem establishes an interesting connection between symmetries of
+the action integral and conservation laws of a dynamical system. The aim of the
+present work is to classify the damped harmonic oscillator problem with respect
+to Noether symmetries and to construct corresponding conservation laws for all
+over-damped, under damped and critical damped cases. For each case we obtain
+maximum five linearly independent group generators which provide related five
+conserved quantities. Remarkably, after obtaining complete set of invariant
+quantities we obtain analytical solutions for each case. In the current work,
+we also introduce a new Lagrangian for the damped harmonic oscillator. Though
+the form of this new Lagrangian and presented by Bateman are completely
+different, yet it generates same set of Noether symmetries and conserved
+quantities. So, this new form of Lagrangian we are presenting here may be
+seriously interesting for the physicists. Moreover, we also find the Lie
+algebras of Noether symmetries and point out some interesting aspects of
+results related to Noether symmetries and first integrals of damped harmonic
+oscillator which perhaps not reported in the earlier studies.",2205.10525v1
+2023-01-31,The emergence of soft-glassy mechanics in simulated foams,"Several seemingly different soft materials, including foams, cells, and many
+complex fluids, exhibit remarkably similar rheological properties and
+microscopic dynamics, termed soft glassy mechanics. Here, we show that such
+behavior emerges from a simple model of a damped ripening foam, for
+sufficiently weak damping. In particular, we observe intermittent avalanchey
+dynamics, bubble super-diffusion, and power-law rheology that vary as the
+damping factor is changed. In the limit of weak damping, the dynamics are
+determined by the tortuous low-lying portions of the energy landscape, as
+described in a recent study. For strong damping the viscous stresses cause the
+system configuration to evolve along higher energy paths, washing out
+small-scale tortuosity and producing motion with an increasingly ballistic
+character. Using a microrheological approach, the linear viscoelastic response
+of the model can be efficiently calculated. This resembles the power-law
+rheology expected for soft glassy mechanics, but unexpectedly, is only weakly
+sensitive to the damping parameter. Lastly, we study the reported memory effect
+in foams after large perturbations and find that the timescale of the memory
+goes to zero as the damping parameter vanishes, suggesting that the effect is
+due to viscous stress relaxation rather than slow structural changes stabilized
+by the energy landscape.",2301.13400v1
+2023-02-13,Thickness and temperature dependent damping in La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ epitaxial films,"The damping of La0.67Sr0.33MnO3 (LSMO) epitaxial films as a function of
+thickness at different temperatures was studied. The competition between two
+scattering types (\r{ho}-like and {\sigma}-like) with entirely distinct
+thickness and temperature dependencies resulted in complicated damping
+behavior. The behavior of {\sigma}-like damping in LSMO films is consistent
+with the behavior in magnetic metal films. However, because \r{ho}-like damping
+is sensitive to the fine electron structure near the Fermi surface, the
+distortion of the oxygen octahedra controlled by the film thickness is an
+important factor in controlling the damping. Our study demonstrates that the
+complexity of damping in LSMO epitaxial films is a consequence of
+strong-correlation effects, which are characteristic of complex
+transition-metal oxides.",2302.06099v3
+1998-05-07,Discovery of z=0.0912 and z=0.2212 Damped Lyman-alpha Absorption Line Systems Toward the Quasar OI 363: Limits on the Nature of Damped Lyman-alpha Galaxies,"The discovery of a z_abs = 0.0912 damped Lyman-alpha absorption-line system
+in the HST-FOS ultraviolet spectrum of the quasar OI 363 (0738+313) is
+reported. This is the lowest redshift quasar damped Lyman-alpha system known.
+Its neutral hydrogen column density is N(HI) = 1.5(+/- 0.2) E21 atoms/cm^2,
+which easily exceeds the classical criterion for damped Lyman-alpha of N(HI)
+greater than or equal to 2E20 atoms/cm^2. Remarkably, a z_abs = 0.2212 damped
+system with N(HI) = 7.9(+/- 1.4) E20 atoms/cm^2 has also been discovered in the
+same spectrum.
+  In the past, the standard paradigm for damped Lyman-alpha systems has been
+that they arise in galactic or protogalactic HI disks with low impact
+parameters in luminous galaxies. However, WIYN imaging of the OI 363 field
+shows that none of the galaxies visible in the vicinity of the quasar is a
+luminous gas-rich spiral with low impact parameter, either at z = 0.0912 or z =
+0.2212. Thus, these damped systems are among the clearest examples yet of cases
+that are inconsistent with the standard damped Lyman-alpha - HI-disk paradigm.",9805093v1
+2008-01-24,Attenuation of small-amplitude oscillations in a prominence-corona model with a transverse magnetic field,"Small-amplitude prominence oscillations are usually damped after a few
+periods. We study the attenuation of non-adiabatic magnetoacoustic waves in a
+slab prominence embedded in the coronal medium. We assume an equilibrium
+configuration with a transverse magnetic field to the slab axis and investigate
+wave damping by thermal conduction and radiative losses. The differential MHD
+equations that govern linear slow and fast modes are numerically solved to
+obtain the complex oscillatory frequency and the corresponding eigenfunctions.
+We find that coronal thermal conduction and radiative losses from the
+prominence plasma reveal as the most relevant damping mechanisms. Both
+mechanisms govern together the attenuation of hybrid modes, whereas prominence
+radiation is responsible for the damping of internal modes and coronal
+conduction essentially dominates the attenuation of external modes. In
+addition, the energy transfer between the prominence and the corona caused by
+thermal conduction has a noticeable effect on the wave stability, radiative
+losses from the prominence plasma being of paramount importance for the thermal
+stability of fast modes. We conclude that slow modes are efficiently damped,
+with damping times compatible with observations. On the contrary, fast modes
+are less attenuated by non-adiabatic effects and their damping times are
+several orders of magnitude larger than those observed. The presence of the
+corona causes a decrease of the damping times with respect to those of an
+isolated prominence slab, but its effect is still insufficient to obtain
+damping times of the order of the period in the case of fast modes.",0801.3744v2
+2010-04-26,Selective spatial damping of propagating kink waves due to resonant absorption,"There is observational evidence of propagating kink waves driven by
+photospheric motions. These disturbances, interpreted as kink
+magnetohydrodynamic (MHD) waves are attenuated as they propagate upwards in the
+solar corona. In this paper we show that resonant absorption provides a simple
+explanation to the spatial damping of these waves. Kink MHD waves are studied
+using a cylindrical model of solar magnetic flux tubes which includes a
+non-uniform layer at the tube boundary. Assuming that the frequency is real and
+the longitudinal wavenumber complex, the damping length and damping per
+wavelength produced by resonant absorption are analytically calculated. The
+damping length of propagating kink waves due resonant absorption is a
+monotonically decreasing function of frequency. For kink waves with low
+frequencies the damping length is exactly inversely proportional to frequency
+and we denote this as the TGV relation. When moving to high frequencies the TGV
+relation continues to be an exceptionally good approximation of the actual
+dependency of the damping length on frequency. This dependency means that
+resonant absorption is selective as it favours low frequency waves and can
+efficiently remove high frequency waves from a broad band spectrum of kink
+waves. It is selective as the damping length is inversely proportional to
+frequency so that the damping becomes more severe with increasing frequency.
+This means that radial inhomogeneity can cause solar waveguides to be a natural
+low-pass filter for broadband disturbances. Hence kink wave trains travelling
+along, e.g., coronal loops, will have a greater proportion of the high
+frequency components dissipated lower down in the atmosphere. This could have
+important consequences with respect to the spatial distribution of wave heating
+in the solar atmosphere.",1004.4468v1
+2011-04-10,Spatial Damping of Propagating Kink Waves Due to Resonant Absorption: Effect of Background Flow,"Observations show the ubiquitous presence of propagating magnetohydrodynamic
+(MHD) kink waves in the solar atmosphere. Waves and flows are often observed
+simultaneously. Due to plasma inhomogeneity in the perpendicular direction to
+the magnetic field, kink waves are spatially damped by resonant absorption. The
+presence of flow may affect the wave spatial damping. Here, we investigate the
+effect of longitudinal background flow on the propagation and spatial damping
+of resonant kink waves in transversely nonuniform magnetic flux tubes. We
+combine approximate analytical theory with numerical investigation. The
+analytical theory uses the thin tube (TT) and thin boundary (TB) approximations
+to obtain expressions for the wavelength and the damping length. Numerically,
+we verify the previously obtained analytical expressions by means of the full
+solution of the resistive MHD eigenvalue problem beyond the TT and TB
+approximations. We find that the backward and forward propagating waves have
+different wavelengths and are damped on length scales that are inversely
+proportional to the frequency as in the static case. However, the factor of
+proportionality depends on the characteristics of the flow, so that the damping
+length differs from its static analogue. For slow, sub-Alfvenic flows the
+backward propagating wave gets damped on a shorter length scale than in the
+absence of flow, while for the forward propagating wave the damping length is
+longer. The different properties of the waves depending on their direction of
+propagation with respect to the background flow may be detected by the
+observations and may be relevant for seismological applications.",1104.1791v1
+2013-02-08,On the Damping-Induced Self-Recovery Phenomenon in Mechanical Systems with Several Unactuated Cyclic Variables,"The damping-induced self-recovery phenomenon refers to the fundamental
+property of underactuated mechanical systems: if an unactuated cyclic variable
+is under a viscous damping-like force and the system starts from rest, then the
+cyclic variable will always move back to its initial condition as the actuated
+variables come to stop. The regular momentum conservation phenomenon can be
+viewed as the limit of the damping-induced self-recovery phenomenon in the
+sense that the self-recovery phenomenon disappears as the damping goes to zero.
+This paper generalizes the past result on damping-induced self-recovery for the
+case of a single unactuated cyclic variable to the case of multiple unactuated
+cyclic variables. We characterize a class of external forces that induce new
+conserved quantities, which we call the damping-induced momenta. The
+damping-induced momenta yield first-order asymptotically stable dynamics for
+the unactuated cyclic variables under some conditions, thereby inducing the
+self-recovery phenomenon. It is also shown that the viscous damping-like forces
+impose bounds on the range of trajectories of the unactuated cyclic variables.
+Two examples are presented to demonstrate the analytical discoveries: the
+planar pendulum with gimbal actuators and the three-link planar manipulator on
+a horizontal plane.",1302.2109v1
+2016-07-06,Damping of Alfven waves by Turbulence and its Consequences: from Cosmic-Rays Streaming to Launching Winds,"This paper considers turbulent damping of Alfven waves in magnetized plasmas.
+We identify two cases of damping, one related to damping of cosmic rays
+streaming instability, the other related to damping of Alfven waves emitted by
+a macroscopic wave source, e.g. stellar atmosphere. The physical difference
+between the two cases is that in the former case the generated waves are
+emitted in respect to the local direction of magnetic field, in the latter in
+respect to the mean field. The scaling of damping is different in the two
+cases. We the regimes of turbulence ranging from subAlfvenic to superAlfvenic
+we obtain analytical expressions for the damping rates and define the ranges of
+applicability of these expressions. Describing the damping of the streaming
+instability, we find that for subAlfvenic turbulence the range of cosmic ray
+energies influenced by weak turbulence is unproportionally large compared to
+the range of scales that the weak turbulence is present. On the contrary, the
+range of cosmic ray energies affected by strong Alfvenic turbulence is rather
+limited. A number of astrophysical applications of the process ranging from
+launching of stellar and galactic winds to propagation of cosmic rays in
+galaxies and clusters of galaxies is considered. In particular, we discuss how
+to reconcile the process of turbulent damping with the observed isotropy of the
+Milky Way cosmic rays.",1607.02042v1
+2018-01-18,Quantum Landau damping in dipolar Bose-Einstein condensates,"We consider Landau damping of elementary excitations in Bose-Einstein
+condensates (BECs) with dipolar interactions. We discuss quantum and
+quasi-classical regimes of Landau damping. We use a generalized wave-kinetic
+description of BECs which, apart from the long range dipolar interactions, also
+takes into account the quantum fluctuations and the finite energy corrections
+to short-range interactions. Such a description is therefore more general than
+the usual mean field approximation. The present wave-kinetic approach is well
+suited for the study of kinetic effects in BECs, such as those associated with
+Landau damping, atom trapping and turbulent diffusion. The inclusion of quantum
+fluctuations and energy corrections change the dispersion relation and the
+damping rates, leading to possible experimental signatures of these effects.
+  Quantum Landau damping is described with generality, and particular examples
+of dipole condensates in two and three dimensions are studied. The occurrence
+of roton-maxon configurations, and their relevance to Landau damping is also
+considered in detail, as well as the changes introduced by the three different
+processes, associated with dipolar interactions, quantum fluctuations and
+finite energy range collisions. The present approach is mainly based on a
+linear perturbative procedure, but the nonlinear regime of Landau damping,
+which includes atom trapping and atom diffusion, is also briefly discussed.",1801.06256v1
+2020-05-31,Optimal decay rates of the compressible Euler equations with time-dependent damping in $\mathbb R^n$: (I) under-damping case,"This paper is concerned with the multi-dimensional compressible Euler
+equations with time-dependent damping of the form
+$-\frac{\mu}{(1+t)^\lambda}\rho\boldsymbol u$ in $\mathbb R^n$, where $n\ge2$,
+$\mu>0$, and $\lambda\in[0,1)$. When $\lambda>0$ is bigger, the damping effect
+time-asymptotically gets weaker, which is called under-damping. We show the
+optimal decay estimates of the solutions such that $\|\partial_x^\alpha
+(\rho-1)\|_{L^2(\mathbb R^n)}\approx
+(1+t)^{-\frac{1+\lambda}{2}(\frac{n}{2}+|\alpha|)}$, and $\|\partial_x^\alpha
+\boldsymbol u\|_{L^2(\mathbb R^n)}\approx
+(1+t)^{-\frac{1+\lambda}{2}(\frac{n}{2}+|\alpha|)-\frac{1-\lambda}{2}}$, and
+see how the under-damping effect influences the structure of the Euler system.
+Different from the traditional view that the stronger damping usually makes the
+solutions decaying faster, here surprisingly we recognize that the weaker
+damping with $0\le\lambda<1$ enhances the faster decay for the solutions. The
+adopted approach is the technical Fourier analysis and the Green function
+method. The main difficulties caused by the time-dependent damping lie in
+twofold: non-commutativity of the Fourier transform of the linearized operator
+precludes explicit expression of the fundamental solution; time-dependent
+evolution implies that the Green matrix $G(t,s)$ is not translation invariant,
+i.e., $G(t,s)\ne G(t-s,0)$. We formulate the exact decay behavior of the Green
+matrices $G(t,s)$ with respect to $t$ and $s$ for both linear wave equations
+and linear hyperbolic system, and finally derive the optimal decay rates for
+the nonlinear Euler system.",2006.00401v1
+2022-08-17,Anti-parity-time symmetry hidden in a damping linear resonator,"Phase transition from the over-damping to under-damping states is a
+ubiquitous phenomenon in physical systems. However, what kind of symmetry is
+broken associated with this phase transition remains unclear. Here, we discover
+that this phase transition is determined by an anti-parity-time
+(anti-$\mathcal{PT}$) symmetry hidden in a single damping linear resonator,
+which is significantly different from the conventional
+anti-$\mathcal{PT}$-symmetric systems with two or more modes. We show that the
+breaking of the anti-$\mathcal{PT}$ symmetry yields the phase transition from
+the over-damping to under-damping states, with an exceptional point (EP)
+corresponding to the critical-damping state. Moreover, we propose an
+optomechanical scheme to show this anti-$\mathcal{PT}$ symmetry breaking by
+using the optical spring effect in a quadratic optomechanical system. We also
+suggest an optomechanical sensor with the sensitivity enhanced significantly
+around the EPs for the anti-$\mathcal{PT}$ symmetry breaking. Our work unveils
+the anti-$\mathcal{PT}$ symmetry hidden in damping oscillations and hence opens
+up new possibilities for exploiting wide anti-$\mathcal{PT}$ symmetry
+applications in single damping linear resonators.",2208.08187v2
+1996-12-10,Collisional matter-phase damping in Bose-condensed gas,"Collisional damping of the excitations in a Bose-condensed gas is
+investigated over the wide range of energies and temperatures. Numerical
+results for the damping rate are presented and a number of asymptotic and
+interpolating expressions for it are derived.",9612086v1
+2001-11-29,Tensor form of magnetization damping,"A tensor form of phenomenological damping is derived for small magnetization
+motions. This form reflects basic physical relaxation processes for a general
+uniformly magnetized particle or film. Scalar Landau-Lifshitz damping is found
+to occur only for two special cases of system symmetry.",0111566v1
+1999-07-28,An effective relaxation-time approach to collisionless quark-gluon plasma,"We present an effective relaxation-time theory to study the collisionless
+quark-gluon plasma. Applying this method we calculate the damping rate to be of
+order $g^2T$ and find plasmon scattering is the damping mechanism. The damping
+for the transverse mode is stronger than the longitudinal one.",9907526v1
+1999-11-16,Dynamical resummation and damping in the O(N) model,"A general real-time formalism is developed to resum the self-energy operator
+of broken symmetry scalar field theories in form of self-consistent gap
+equations for the spectral function. The solution of the equations is
+approximated with finite lifetime quasi-particles. In the Landau damping rates
+viscosity terms, analogous to gauge theories, appear, what leads to a finite
+damping rate for the long wavelength Goldstone modes.",9911374v1
+1993-03-24,On the Quantizations of the Damped Systems,"Based on a simple observation that a classical second order differential
+equation may be decomposed into a set of two first order equations, we
+introduce a Hamiltonian framework to quantize the damped systems. In
+particular, we analyze the system of a linear damped harmonic oscillator and
+demonstrate that the time evolution of the Schr\""odinger equation is
+unambiguously determined.",9303137v1
+2006-01-09,Energy decay for damped wave equations on partially rectangular domains,"We consider the wave equation with a damping term on a partially rectangular
+planar domain, assuming that the damping is concentrated close to the
+non-rectangular part of the domain. Polynomial decay estimates for the energy
+of the solution are established.",0601195v1
+2002-06-07,Resonant states and classical damping,"Using Koopman's approach to classical dynamical systems we show that the
+classical damping may be interpreted as appearance of resonant states of the
+corresponding Koopman's operator. It turns out that simple classical damped
+systems give rise to discrete complex spectra. Therefore, the corresponding
+generalized eigenvectors may be interpreted as classical resonant states.",0206009v1
+2002-12-19,Trapped particle bounds on stimulated scatter in the large k/kD regime,"In the strongly damped regime, the convective gain rate for stimulated
+scatter varies inversely with the plasma wave damping rate. Electron trapping
+effects reduce the damping but also lead to loss of resonance for large enough
+amplitude waves. This leads to a gain rate bound and corresponding optimum
+scattered light frequency and plasma wave amplitude.",0212071v1
+2003-02-03,Oscillator damping with more than one mechanism of internal friction dissipation,"The author's modified Coulomb damping model has been generalized to
+accommodate internal friction that derives from several dissipation mechanisms
+acting simultaneously. Because of its fundamental nonlinear nature, internal
+friction damping causes the quality factor Q of an oscillator in free-decay to
+change in time. Examples are given which demonstrate reasonable agreement
+between theory and experiment.",0302003v1
+2003-02-15,Anisotropic Internal Friction Damping,"The mechanical damping properties of sheet polaroid material have been
+studied with a physical pendulum. The polaroid samples were placed under the
+knife-edges of the pendulum, which was operated in free-decay at a period in
+the vicinity of 10 s. With the edges oriented parallel to the direction of the
+long molecular chains in the polaroid, it was found that the damping was more
+than 10% smaller than when oriented perpendicular to the chains.",0302055v1
+2006-08-07,Study of the Damped Pendulum,"Experiments on the oscillatory motion of a suspended bar magnet throws light
+on the damping effects acting on the pendulum. The viscous drag offered by air
+was found the be the main contributor for slowing the pendulum down. The nature
+and magnitude of the damping effects were shown to be strongly dependent on the
+amplitude.",0608071v1
+1995-02-27,Quantum Oscillator with Kronig-Penney Excitation in Different Regimes of Damping,"There are discussed the exact solution of the time--dependent Schr\""{o}dinger
+equation for a damped quantum oscillator subject to a periodical frequency
+delta--kicks describing squeezed states which are expressed in terms of
+Chebyshev polynomials. The cases of strong and weak damping are investigated in
+the frame of Caldirola--Kanai model.",9502023v1
+2007-03-12,Quantum estimation of a damping constant,"We discuss an interferometric approach to the estimation of quantum
+mechanical damping. We study specific classes of entangled and separable probe
+states consisting of superpositions of coherent states. Based on the assumption
+of limited quantum resources we show that entanglement improves the estimation
+of an unknown damping constant.",0703091v2
+2008-11-07,Asymptotic stability of the wave equation on compact surfaces and locally distributed damping - A sharp result,"This paper is concerned with the study of the wave equation on compact
+surfaces and locally distributed damping. We study the case where the damping
+is effective in a well-chosen subset of arbitrarily small measure.",0811.1190v1
+2008-11-07,Uniform Stabilization of the wave equation on compact surfaces and locally distributed damping,"This paper is concerned with the study of the wave equation on compact
+surfaces and locally distributed damping. We study the case where the damping
+is effective on the complement of visible umbilical sets.",0811.1204v1
+2010-11-20,Enhanced damping of ion acoustic waves in dense plasmas,"A theory for the ion acoustic wave damping in dense plasmas and warm dense
+matter, accounting for the Umklapp process, is presented. A higher decay rate
+compared to the prediction from the Landau damping theory is predicted for
+high-Z dense plasmas where the electron density ranges from $10^{21}$ to $
+10^{24} \mathrm{cm^{-3}}$ and the electron temperature is moderately higher
+than the Fermi energy.",1011.4607v1
+2012-05-16,Enhanced coupling design of a detuned damped structure for clic,"The key feature of the improved coupling design in the Damped Detuned
+Structure (DDS) is focused on the four manifolds. Rectangular geometry slots
+and rectangular manifolds are used. This results in a significantly stronger
+coupling to the manifolds compared to the previous design. We describe the new
+design together with its wakefield damping properties.",1205.3590v1
+2012-06-26,On the $L^{2}$-critical nonlinear Schrödinger Equation with a nonlinear damping,"We consider the Cauchy problem for the $L^{2}$-critical nonlinear
+Schr\""{o}dinger equation with a nonlinear damping. According to the power of
+the damping term, we prove the global existence or the existence of finite time
+blowup dynamics with the log-log blow-up speed for $\|\nabla u(t)\|_{L^2}$.",1206.6082v4
+2012-10-12,Semi-linear wave equations with effective damping,"We study the Cauchy problem for the semi-linear damped wave equation in any
+space dimension. We assume that the time-dependent damping term is effective.
+We prove the global existence of small energy data solutions in the
+supercritical case.",1210.3493v1
+2012-12-10,Strongly damped wave equation with exponential nonlinearities,"In this paper, we study the initial boundary value problem for the two
+dimensional strong damped wave equation with exponentially growing source and
+damping terms. We first show the well-posedness of this problem and then prove
+the existence of the global attractor in $(H_{0}^{1}(\Omega)\cap
+L^{\infty}(\Omega))\times L^{2}(\Omega)$.",1212.2180v2
+2013-10-27,Exponential decay of solutions for the plate equation with localized damping,"In this paper, we give positive answer to the open question raised in [E.
+Zuazua, Exponential decay for the semilinear wave equation with localized
+damping in unbounded domains. J. Math. Pures Appl., 70 (1991) 513--529] on the
+exponential decay of solutions for the semilinear plate equation with localized
+damping.",1310.7243v3
+2014-03-07,Landau damping in Sobolev spaces for the Vlasov-HMF model,"We consider the Vlasov-HMF (Hamiltonian Mean-Field) model. We consider
+solutions starting in a small Sobolev neighborhood of a spatially homogeneous
+state satisfying a linearized stability criterion (Penrose criterion). We prove
+that these solutions exhibit a scattering behavior to a modified state, which
+implies a nonlinear Landau damping effect with polynomial rate of damping.",1403.1668v2
+2015-03-30,Damping to prevent the blow-up of the Korteweg-de Vries equation,"We study the behavior of the solution of a generalized damped KdV equation
+$u_t + u_x + u_{xxx} + u^p u_x + \mathscr{L}_{\gamma}(u)= 0$. We first state
+results on the local well-posedness. Then when $p \geq 4$, conditions on
+$\mathscr{L}_{\gamma}$ are given to prevent the blow-up of the solution.
+Finally, we numerically build such sequences of damping.",1503.08559v1
+2015-11-25,A Proposal of a Damping Term for the Relativistic Euler Equations,"We introduce a damping term for the special relativistic Euler equations in
+$3$-D and show that the equations reduce to the non-relativistic damped Euler
+equations in the Newtonian limit. We then write the equations as a symmetric
+hyperbolic system for which local-in-time existence of smooth solutions can be
+shown.",1511.08183v1
+2016-01-27,Concatenated Codes for Amplitude Damping,"We discuss a method to construct quantum codes correcting amplitude damping
+errors via code concatenation. The inner codes are chosen as asymmetric
+Calderbank-Shor-Steane (CSS) codes. By concatenating with outer codes
+correcting symmetric errors, many new codes with good parameters are found,
+which are better than the amplitude damping codes obtained by any previously
+known construction.",1601.07423v1
+2016-03-29,Generalized damped Milne-Pinney equation and Chiellini method,"We adopt the Chiellini integrability method to find the solutions of various
+generalizations of the damped Milne-Pinney equations. In particular, we find
+the solution of the damped Ermakov-Painlev\'e II equation and generalized
+dissipative Milne-Pinney equation.",1603.08747v2
+2017-12-07,Damped wave equations on compact hyperbolic surfaces,"We prove exponential decay of energy for solutions of the damped wave
+equation on compact hyperbolic surfaces with regular initial data as long as
+the damping is nontrivial. The proof is based on a similar strategy as in
+Dyatlov-Jin and in particular, uses the fractal uncertainty principle proved in
+Bourgain-Dyatlov.",1712.02692v1
+2018-09-10,Logarithmic Decay of a Wave Equation with Kelvin-Voigt Damping,"In this paper we analyze the long time behavior of a wave equation with local
+Kelvin-Voigt Damping. Through introducing proper class symbol and
+pseudo-differential calculus, we obtain a Carleman estimate, and then establish
+an estimate on the corresponding resolvent operator. As a result, we show the
+logarithmic decay rate for energy of the system without any geometric
+assumption on the subdomain on which the damping is effective.",1809.03196v1
+2018-11-07,Slow-dissipation limit of the harmonic oscillator with general power-law damping,"An approximate solution is presented for simple harmonic motion in the
+presence of damping by a force which is a general power-law function of the
+velocity. The approximation is shown to be quite robust, allowing for a simple
+way to investigate amplitude decay in the presence of general types of weak,
+nonlinear damping.",1811.02953v2
+2019-09-25,Forced Coupled Duffing Oscillators with Nonlinear Damping: Resonance and Antiresonance,"In this work, we investigate resonance and antiresonance behaviour in forced
+coupled Duffing oscillators with nonlinear damping. Further, we will analyse
+the parameter dependence of the frequency response and stability. In the course
+of all the analysis, emphasis shall be on how different damping mechanisms
+contrast against each other.",1909.11390v1
+2020-04-21,Damping rate limitations for transverse dampers in large hadron colliders,"The paper focuses on two issues important for design and operation of
+bunch-by-bunch transverse damper in a very large hadron collider, where fast
+damping is required to suppress beam instabilities and noise induced emittance
+growth. The first issue is associated with kick variation along a bunch which
+affects the damping of head-tail modes. The second issue is associated with
+affect of damper noise on the instability threshold.",2004.10249v2
+2021-02-01,Global existence for semilinear wave equations with scaling invariant damping in 3-D,"Global existence for small data Cauchy problem of semilinear wave equations
+with scaling invariant damping in 3-D is established in this work, assuming
+that the data are radial and the constant in front of the damping belongs to
+$[1.5, 2)$. The proof is based on a weighted $L^2-L^2$ estimate for
+inhomogeneous wave equation, which is established by interpolating between
+energy estimate and Morawetz type estimate.",2102.00909v1
+2022-02-10,Stochastic optimal control for nonlinear damped network dynamics,"We present a stochastic optimal control problem for a tree network. The
+dynamics of the network are governed by transport equations with a special
+emphasis on the non-linear damping function. Demand profiles at the network
+sinks are modelled by a stochastic differential equations. An explicit optimal
+inflow into the network is determined and numerical simulations are presented
+to show the effects for different choices of the non-linear damping.",2202.05114v1
+2022-03-03,Conformal symmetry in damped Pais-Uhlenbeck oscillator,"Two Lagrangian formulations for describing of the damped harmonic oscillator
+have been introduced by Bateman. For these models we construct higher
+derivative generalization which enjoys the l-conformal Newton-Hooke symmetry.
+The dynamics of generalized systems corresponds to the damped Pais-Uhlenbeck
+oscillator for a particular choice of its frequencies.",2203.01651v1
+2022-10-31,An adaptive damped Newton method for strongly monotone and Lipschitz continuous operator equations,"We will consider the damped Newton method for strongly monotone and Lipschitz
+continuous operator equations in a variational setting. We will provide a very
+accessible justification why the undamped Newton method performs better than
+its damped counterparts in a vicinity of a solution. Moreover, in the given
+setting, an adaptive step-size strategy will be presented, which guarantees the
+global convergence and favours an undamped update if admissible.",2210.17107v1
+2022-11-19,Blow up and lifespan estimates for systems of semi-linear wave equations with damping and potential,"In this paper, we consider the semi-linear wave systems with
+power-nonlinearities and a large class of space-dependent damping and
+potential. We obtain the same blow-up regions and the lifespan estimates for
+three types wave systems, compared with the systems without damping and
+potential.",2211.10639v1
+2023-08-10,Pathwise uniqueness for stochastic heat and damped equations with Hölder continuous drift,"In this paper, we prove pathwise uniqueness for stochastic differential
+equations in infinite dimension. Under our assumptions, we are able to consider
+the stochastic heat equation up to dimension $3$, the stochastic damped wave
+equation in dimension $1$ and the stochastic Euler-Bernoulli damped beam
+equation up to dimension $3$. We do not require that the so-called {\it
+structure condition} holds true.",2308.05415v1
+2023-10-30,Beliaev damping in Bose gas,"According to the Bogoliubov theory the low energy behaviour of the Bose gas
+at zero temperature can be described by non-interacting bosonic quasiparticles
+called phonons. In this work the damping rate of phonons at low momenta, the
+so-called Beliaev damping, is explained and computed with simple arguments
+involving the Fermi Golden Rule and Bogoliubov's quasiparticles.",2310.20070v1
+2023-11-25,Energy scattering for the unsteady damped nonlinear Schrodinger equation,"We investigate the large time behavior of the solutions to the nonlinear
+focusing Schr\""odinger equation with a time-dependent damping in the energy
+sub-critical regime. Under non classical assumptions on the unsteady damping
+term, we prove some scattering results in the energy space.",2311.14980v2
+2017-10-18,Direct detection of metal-insulator phase transitions using the modified Backus-Gilbert method,"The detection of the (semi)metal-insulator phase transition can be extremely
+difficult if the local order parameter which characterizes the ordered phase is
+unknown.In some cases, it is even impossible to define a local order parameter:
+the most prominent example of such system is the spin liquid state. This state
+was proposed to exist in theHubbard model on the hexagonal lattice in a region
+between the semimetal phase and the antiferromagnetic insulator phase. The
+existence of this phase has been the subject of a long debate. In order to
+detect these exotic phases we must use alternative methods to those used for
+more familiar examples of spontaneous symmetry breaking. We have modified the
+Backus-Gilbert method of analytic continuation which was previously used in the
+calculation of the pion quasiparticle mass in lattice QCD. The modification of
+the method consists of the introduction of the Tikhonov regularization scheme
+which was used to treat the ill-conditioned kernel. This modified
+Backus-Gilbert method is applied to the Euclidean propagators in momentum space
+calculated using the hybridMonte Carlo algorithm. In this way, it is possible
+to reconstruct the full dispersion relation and to estimate the mass gap, which
+is a direct signal of the transition to the insulating state. We demonstrate
+the utility of this method in our calculations for the Hubbard model on the
+hexagonal lattice. We also apply the method to the metal-insulator phase
+transition in the Hubbard-Coulomb model on the square lattice.",1710.06675v1
+2020-09-14,Bounds and Code Constructions for Partially Defect Memory Cells,"This paper considers coding for so-called partially stuck memory cells. Such
+memory cells can only store partial information as some of their levels cannot
+be used due to, e.g., wear out. First, we present a new code construction for
+masking such partially stuck cells while additionally correcting errors. This
+construction (for cells with $q >2$ levels) is achieved by generalizing an
+existing masking-only construction in [1] (based on binary codes) to correct
+errors as well. Compared to previous constructions in [2], our new construction
+achieves larger rates for many sets of parameters. Second, we derive a
+sphere-packing (any number of $u$ partially stuck cells) and a
+Gilbert-Varshamov bound ($u<q$ partially stuck cells) for codes that can mask a
+certain number of partially stuck cells and correct errors additionally. A
+numerical comparison between the new bounds and our previous construction of
+PSMCs for the case $u<q$ in [2] shows that our construction lies above the
+Gilbert-Varshamov-like bound for several code parameters.",2009.06512v3
+2002-02-21,Mechanisms of spin-polarized current-driven magnetization switching,"The mechanisms of the magnetization switching of magnetic multilayers driven
+by a current are studied by including exchange interaction between local
+moments and spin accumulation of conduction electrons. It is found that this
+exchange interaction leads to two additional terms in the
+Landau-Lifshitz-Gilbert equation: an effective field and a spin torque. Both
+terms are proportional to the transverse spin accumulation and have comparable
+magnitudes.",0202363v1
+2005-10-30,Domain instability during precessional magnetization reversal,"Spin wave equations in the non-equilibrium precessing state of a
+ferromagnetic system are found. They show a spin-wave instability towards
+growing domains of stable magnetization. Precession of the uniform
+magnetization mode is described by the Landau Lifshitz equation with the
+exponentially growing in time effective Gilbert dissipation constant that could
+have both signs. On the developed stages of the domain instability a
+non-stationary picture of domain chaos is observed.",0510817v1
+1991-12-02,Perturbations of a Stringy Black Hole,"We extend the three dimensional stringy black hole of Horne and Horowitz to
+four dimensions. After a brief discussion of the global properties of the
+metric, we discuss the stability of the background with respect to small
+perturbations, following the methods of Gilbert and of Chandrasekhar. The
+potential for axial perturbations is found to be positive definite.",9112001v2
+1996-05-06,Finitely presented subgroups of automatic groups and their isoperimetric functions,"We describe a general technique for embedding certain amalgamated products
+into direct products. This technique provides us with a way of constructing a
+host of finitely presented subgroups of automatic groups which are not even
+asynchronously automatic. We can also arrange that such subgroups satisfy, at
+best, an exponential isoperimetric inequality.",9605201v1
+1999-07-22,Constructing Hyperbolic Manifolds,"In this paper we show how to obtain representations of Coxeter groups acting
+on H^n to certain classical groups. We determine when the kernel of such a
+representation is torsion-free and thus the quotient a hyperbolic n-manifold.",9907139v1
+2002-02-06,Quaternionic equation for electromagnetic fields in inhomogeneous media,"We show that the Maxwell equations for arbitrary inhomogeneous media are
+equivalent to a single quaternionic equation which can be considered as a
+generalization of the Vekua equation for generalized analytic functions.",0202010v1
+1996-02-29,Error Correction in Quantum Communication,"We show how procedures which can correct phase and amplitude errors can be
+directly applied to correct errors due to quantum entanglement. We specify
+general criteria for quantum error correction, introduce quantum versions of
+the Hamming and the Gilbert-Varshamov bounds and comment on the practical
+implementation of quantum codes.",9602022v1
+2007-05-19,Log-periodic drift oscillations in self-similar billiards,"We study a particle moving at unit speed in a self-similar Lorentz billiard
+channel; the latter consists of an infinite sequence of cells which are
+identical in shape but growing exponentially in size, from left to right. We
+present numerical computation of the drift term in this system and establish
+the logarithmic periodicity of the corrections to the average drift.",0705.2790v1
+2008-04-26,Asymptotic Bound on Binary Self-Orthogonal Codes,"We present two constructions for binary self-orthogonal codes. It turns out
+that our constructions yield a constructive bound on binary self-orthogonal
+codes. In particular, when the information rate R=1/2, by our constructive
+lower bound, the relative minimum distance \delta\approx 0.0595 (for GV bound,
+\delta\approx 0.110). Moreover, we have proved that the binary self-orthogonal
+codes asymptotically achieve the Gilbert-Varshamov bound.",0804.4194v1
+2008-11-14,Scott and Swarup's regular neighbourhood as a tree of cylinders,"Let G be a finitely presented group. Scott and Swarup have constructed a
+canonical splitting of G which encloses all almost invariant sets over
+virtually polycyclic subgroups of a given length. We give an alternative
+construction of this regular neighbourhood, by showing that it is the tree of
+cylinders of a JSJ splitting.",0811.2389v1
+2009-05-04,Self-organized quantum transitions in a spin-electron coupled system,"We investigate quantum dynamics of the excited electronic states in the
+double-exchange model at half-filling by solving coupled equations for the
+quantum evolution of electrons and Landau-Lifshits-Gilbert equation for
+classical spins. The non-adiabatic quantum transitions driving the relaxation
+are coordinated through the self-organized space-time structure of the
+electron/spin dynamics leading to a resonant precession analogous to the ESR
+process.",0905.0311v1
+2009-05-04,Oscillating Ponomarenko dynamo in the highly conducting limit,"This paper considers dynamo action in smooth helical flows in cylindrical
+geometry, otherwise known as Ponomarenko dynamos, with periodic time
+dependence. An asymptotic framework is developed that gives growth rates and
+frequencies in the highly conducting limit of large magnetic Reynolds number,
+when modes tend to be localized on resonant stream surfaces. This theory is
+validated by means of numerical simulations.",0905.0415v1
+2009-07-15,Barnett Effect in Thin Magnetic Films and Nanostructures,"The Barnett effect refers to the magnetization induced by rotation of a
+demagnetized ferromagnet. We describe the location and stability of stationary
+states in rotating nanostructures using the Landau-Lifshitz-Gilbert equation.
+The conditions for an experimental observation of the Barnett effect in
+different materials and sample geometries are discussed.",0907.2648v1
+2009-12-24,Scenarios of Gravitino Dark Matter and their Cosmological and Particle Physics Implications,"I report on some scenarios where the gravitino is the dark matter and the
+supersymmetry breaking mediated by a gauge sector.",0912.4885v1
+2010-07-20,Factoring Permutation Matrices Into a Product of Tridiagonal Matrices,"Gilbert Strang posited that a permutation matrix of bandwidth $w$ can be
+written as a product of $N < 2w$ permutation matrices of bandwidth 1. A proof
+employing a greedy ``parallel bubblesort'' algorithm on the rows of the
+permutation matrix is detailed and further points of interest are elaborated.",1007.3467v1
+2011-05-26,Qu'est-ce qu'une espèce de structures? Genèse et description,"This is an overview (in french) of the Theory of Species for a general
+audience. Basic notions are introduced in a non too technical manner, with an
+explanation of why should one approach the notion of discrete structures in
+this particular way.",1105.5406v1
+2011-12-16,"Reply to the comment of T.Gilbert and D.P.Sanders on ""Capturing correlations in chaotic diffusion by approximation methods""","This is a reply to the comment by Gilbert and Sanders [arXiv:1111.6271
+(2011)]. We point out that their comment is a follow-up of a previous
+discussion which we briefly summarize before we refute their new criticism.",1112.3927v1
+2012-03-24,A new look at finitely generated metabelian groups,"A group is metabelian if its commutator subgroup is abelian. For finitely
+generated metabelian groups, classical commutative algebra, algebraic geometry
+and geometric group theory, especially the latter two subjects, can be brought
+to bear on their study. The object of this paper is to describe some of the new
+ideas and open problems that arise.",1203.5431v1
+2012-06-05,A convergent and precise finite element scheme for Landau-Lifschitz-Gilbert equation,"In this paper, we rigorously study an order 2 scheme that was previously
+proposed by some of the authors. A slight modification is proposed that enables
+us to prove the convergence of the scheme while simplifying in the same time
+the inner iteration.",1206.0997v1
+2013-01-20,Residual properties of groups defined by basic commutators,"In this paper we study the residual nilpotence of groups defined by basic
+commutators. We prove that the so-called Hydra groups as well as certain of
+their generalizations and quotients are, in the main, residually torsion-free
+nilpotent. By way of contrast we give an example of a group defined by two
+basic commutators which is not residually torsion-free nilpotent.",1301.4629v2
+2013-03-21,Anisimov's Theorem for inverse semigroups,"The idempotent problem of a finitely generated inverse semigroup is the
+formal language of all words over the generators representing idempotent
+elements. This note proves that a finitely generated inverse semigroup with
+regular idempotent problem is necessarily finite. This answers a question of
+Gilbert and Noonan Heale, and establishes a generalisation to inverse
+semigroups of Anisimov's Theorem for groups.",1303.5239v1
+2013-10-13,Underwater Gas Expansion and Deflagration,"The underwater combustion of a propane-air mixture in an acrylic cylinder is
+captured on video from multiple angles. This experiment is designed to provide
+visual data and pressure time-histories for future CFD validation studies.",1310.3523v1
+2014-03-12,A semi-discrete scheme for the stochastic Landau-Lifshitz equation,"We propose a new convergent time semi-discrete scheme for the stochastic
+Landau-Lifshitz-Gilbert equation. The scheme is only linearly implicit and does
+not require the resolution of a nonlinear problem at each time step. Using a
+martingale approach, we prove the convergence in law of the scheme up to a
+subsequence.",1403.3016v1
+2014-03-17,Quantum codes from affine variety codes and their subfield-subcodes,"We use affine variety codes and their subfield-subcodes for obtaining quantum
+stabilizer codes via the CSS code construction. With this procedure, we get
+codes with good parameters and a code whose parameters exceed the CSS quantum
+Gilbert-Varshamov bound given by Feng and Ma.",1403.4060v2
+2015-10-19,Decomposability of Finitely Generated Torsion-free Nilpotent Groups,"We describe an algorithm for deciding whether or not a given finitely
+generated torsion-free nilpotent group is decomposable as the direct product of
+nontrivial subgroups.",1510.05632v2
+2016-02-27,On automatic subsets of the Gaussian integers,"Suppose that $a$ and $b$ are multiplicatively independent Gaussian integers,
+that are both of modulus~$\geq \sqrt 5$. We prove that there exist a $X\subset
+\mathbb Z[i]$ which is $a$-automatic but not $b$-automatic. This settles a
+problem of Allouche, Cateland, Gilbert, Peitgen, Shallit, and Skordev.",1602.08579v3
+2016-03-02,On self-dual double circulant codes,"Self-dual double circulant codes of odd dimension are shown to be dihedral in
+even characteristic and consta-dihedral in odd characteristic. Exact counting
+formulae are derived for them and used to show they contain families of codes
+with relative distance satisfying a modified Gilbert-Varshamov bound.",1603.00762v1
+2016-09-22,Manipulation of magnetic Skyrmions with a Scanning Tunneling Microscope,"The dynamics of a single magnetic Skyrmion in an atomic spin system under the
+influence of Scanning Tunneling Microscope is investigated by computer
+simulations solving the Landau-Lifshitz-Gilbert equation. Two possible
+scenarios are described: manipulation with aid of a spin-polarized tunneling
+current and by an electric field created by the scanning tunneling microscope.
+The dynamics during the creation and annihilation process is studied and the
+possibility to move single Skyrmions is showed.",1609.06797v1
+2016-11-03,Quantile Reinforcement Learning,"In reinforcement learning, the standard criterion to evaluate policies in a
+state is the expectation of (discounted) sum of rewards. However, this
+criterion may not always be suitable, we consider an alternative criterion
+based on the notion of quantiles. In the case of episodic reinforcement
+learning problems, we propose an algorithm based on stochastic approximation
+with two timescales. We evaluate our proposition on a simple model of the TV
+show, Who wants to be a millionaire.",1611.00862v1
+2017-01-30,Elementary equivalence vs commensurability for hyperbolic groups,"We study to what extent torsion-free (Gromov)-hyperbolic groups are
+elementarily equivalent to their finite index subgroups. In particular, we
+prove that a hyperbolic limit group either is a free product of cyclic groups
+and surface groups, or admits infinitely many subgroups of finite index which
+are pairwise non elementarily equivalent.",1701.08853v1
+2017-08-01,Imaging from the Inside Out: Inverse Scattering with Photoactivated Internal Sources,"We propose a method to reconstruct the optical properties of a scattering
+medium with subwavelength resolution. The method is based on the solution to
+the inverse scattering problem with photoactivated internal sources. Numerical
+simulations of three-dimensional structures demonstrate that a resolution of
+approximately $\lambda/25$ is achievable.",1708.00128v1
+2017-09-22,On self-dual four circulant codes,"Four circulant codes form a special class of $2$-generator, index $4$,
+quasi-cyclic codes. Under some conditions on their generator matrices they can
+be shown to be self-dual. Artin primitive root conjecture shows the existence
+of an infinite subclass of these codes satisfying a modified Gilbert-Varshamov
+bound.",1709.07548v1
+2018-02-21,Enhanced global signal of neutral hydrogen due to excess radiation at cosmic dawn,"We revisit the global 21cm signal calculation incorporating a possible radio
+background at early times, and find that the global 21cm signal shows a much
+stronger absorption feature, which could enhance detection prospects for future
+21 cm experiments. In light of recent reports of a possible low-frequency
+excess radio background, we propose that detailed 21 cm calculations should
+include a possible early radio background.",1802.07432v1
+2019-03-22,Nonlinear Iterative Hard Thresholding for Inverse Scattering,"We consider the inverse scattering problem for sparse scatterers. An image
+reconstruction algorithm is proposed that is based on a nonlinear
+generalization of iterative hard thresholding. The convergence and error of the
+method was analyzed by means of coherence estimates and compared to numerical
+simulations.",1903.10875v1
+2019-04-06,Phenomenological description of the dynamics of bipartite antiferromagnets in the limit of strong exchange,"The equation of motion of the staggered order parameter is derived in a
+step-by-step manner from the coupled Landau-Lifshitz-Gilbert dynamics of
+bipartite spin moments in the limit of strong antiferromagnetic exchange
+coupling.",1904.03529v4
+2019-04-19,Variational approximation of functionals defined on $1$-dimensional connected sets in $\mathbb{R}^n$,"In this paper we consider the Euclidean Steiner tree problem and, more
+generally, (single sink) Gilbert--Steiner problems as prototypical examples of
+variational problems involving 1-dimensional connected sets in $\mathbb{R}^n$.
+Following the the analysis for the planar case presented in [4], we provide a
+variational approximation through Ginzburg--Landau type energies proving a
+$\Gamma$-convergence result for $n \geq 3$.",1904.09328v1
+2020-03-02,Improved Gilbert-Varshamov Bound for Entanglement-Assisted Asymmetric Quantum Error Correction by Symplectic Orthogonality,"We propose and prove an existential theorem for entanglement-assisted
+asymmetric quantum error correction. Then we demonstrate its superiority over
+the conventional one.",2003.00668v2
+2020-07-14,Competitively Pricing Parking in a Tree,"Motivated by demand-responsive parking pricing systems we consider
+posted-price algorithms for the online metrical matching problem and the online
+metrical searching problem in a tree metric. Our main result is a poly-log
+competitive posted-price algorithm for online metrical searching.",2007.07294v2
+2021-05-14,Very regular solution to Landau-Lifshitz system with spin-polarized transport,"In this paper, we provide a precise description of the compatibility
+conditions for the initial data so that one can show the existence and
+uniqueness of regular short-time solution to the Neumann initial-boundary
+problem of a class of Landau-Lifshitz-Gilbert system with spin-polarized
+transport, which is a strong nonlinear coupled parabolic system with non-local
+energy.",2105.06616v1
+2022-09-23,Limiting Distributions of Sums with Random Spectral Weights,"This paper studies the asymptotic properties of weighted sums of the form
+$Z_n=\sum_{i=1}^n a_i X_i$, in which $X_1, X_2, \ldots, X_n$ are i.i.d.~random
+variables and $a_1, a_2, \ldots, a_n$ correspond to either eigenvalues or
+singular values in the classic Erd\H{o}s-R\'enyi-Gilbert model. In particular,
+we prove central limit-type theorems for the sequences $n^{-1}Z_n$ with varying
+conditions imposed on $X_1, X_2, \ldots, X_n$.",2209.11389v1
+2023-09-16,Expansion of the Critical Intensity for the Random Connection Model,"We derive an asymptotic expansion for the critical percolation density of the
+random connection model as the dimension of the encapsulating space tends to
+infinity. We calculate rigorously the first expansion terms for the Gilbert
+disk model, the hyper-cubic model, the Gaussian connection kernel, and a
+coordinate-wise Cauchy kernel.",2309.08830v1
+2024-03-14,Remarks on the rate of linear vortex symmetrization,"We reformulate results from the paper ``Linear vortex symmetrization: The
+spectral density function"" by Ionescu and the author in simplified forms and
+derive rigorously the bounds given in Bassom and Gilbert (J. Fluid Mech.,
+1998), which provided interesting insights on the vortex symmetrization
+phenomenon.",2403.09397v1
+2003-10-29,Comparing Chemical Abundances of the Damped Lya Systems and Metal-Poor Stars,"I briefly draw comparisons between the fields of damped Lya and metal-poor
+stellar abundances. In particular, I examine their complementary
+age-metallicity relations and comparisons between the damped Lya and dwarf
+galaxy abundance patterns. Regarding the latter, I describe a series of
+problems concerning associating high z damped Lya systems with present-day
+dwarfs.",0310850v1
+2006-12-01,Stochastic excitation and damping of solar-type oscillations,"A review on acoustic mode damping and excitation in solar-type stars is
+presented. Current models for linear damping rates are discussed in the light
+of recent low-degree solar linewidth measurements with emphasis on the
+frequency-dependence of damping rates of low-order modes. Recent developments
+in stochastic excitation models are reviewed and tested against the latest
+high-quality data of solar-like oscillations, such as from alpha Cen A, and
+against results obtained from hydrodynamical simulations.",0612024v1
+1997-08-11,A theoretical study on the damping of collective excitations in a Bose-Einstein condensate,"We study the damping of low-lying collective excitations of condensates in a
+weakly interacting Bose gas model within the framework of imaginary time path
+integral. A general expression of the damping rate has been obtained in the low
+momentum limit for both the very low temperature regime and the higher
+temperature regime. For the latter, the result is new and applicable to recent
+experiments. Theoretical predictions for the damping rate are compared with the
+experimental values.",9708080v3
+1997-09-24,Damping in dilute Bose gases: a mean-field approach,"Damping in a dilute Bose gas is investigated using a mean-field approximation
+which describes the coupled oscillations of condensate and non-condensate atoms
+in the collisionless regime. Explicit results for both Landau and Beliaev
+damping rates are given for non-uniform gases. In the case of uniform systems
+we obtain results for the damping of phonons both at zero and finite
+temperature. The isothermal compressibility of a uniform gas is also discussed.",9709259v1
+2000-09-01,Damped Bogoliubov excitations of a condensate interacting with a static thermal cloud,"We calculate the damping of condensate collective excitations at finite
+temperatures arising from the lack of equilibrium between the condensate and
+thermal atoms. We neglect the non-condensate dynamics by fixing the thermal
+cloud in static equilibrium. We derive a set of generalized Bogoliubov
+equations for finite temperatures that contain an explicit damping term due to
+collisional exchange of atoms between the two components. We have numerically
+solved these Bogoliubov equations to obtain the temperature dependence of the
+damping of the condensate modes in a harmonic trap. We compare these results
+with our recent work based on the Thomas-Fermi approximation.",0009021v2
+2000-11-20,Cavity assisted quasiparticle damping in a Bose-Einstein condensate,"We consider an atomic Bose-Einstein condensate held within an optical cavity
+and interacting with laser fields. We show how the interaction of the cavity
+mode with the condensate can cause energy due to excitations to be coupled to a
+lossy cavity mode, which then decays, thus damping the condensate, how to
+choose parameters for damping specific excitations, and how to target a range
+of different excitations to potentially produce extremely cold condensates.",0011341v2
+2002-12-16,The nonlinear damping of Bose-Einstein condensate oscillations at ultra-low temperatures,"We analyze the damping of the transverse breathing mode in an elongated trap
+at ultralow temperatures. The damping occurs due to the parametric resonance
+entailing the energy transfer to the longitudinal degrees of freedom. It is
+found that the nonlinear coupling between the transverse and discrete
+longitudinal modes can result in an anomalous behavior of the damping as a
+function of time with the partially reversed pumping of the breathing mode. The
+picture revealed explains the results observed in [16].",0212377v2
+2004-08-27,Tunable magnetization damping in transition metal ternary alloys,"We show that magnetization damping in Permalloy, Ni80Fe20 (``Py''), can be
+enhanced sufficiently to reduce post-switching magnetization precession to an
+acceptable level by alloying with the transition metal osmium (Os). The damping
+increases monotonically upon raising the Os-concentration in Py, at least up to
+9% of Os. Other effects of alloying with Os are suppression of magnetization
+and enhancement of in-plane anisotropy. Magnetization damping also increases
+significantly upon alloying with the five other transition metals included in
+this study (4d-elements: Nb, Ru, Rh; 5d-elements: Ta, Pt) but never as strongly
+as with Os.",0408608v1
+2005-03-06,Nonlinear damping in nanomechanical beam oscillator,"We investigate the impact of nonlinear damping on the dynamics of a
+nanomechanical doubly clamped beam. The beam is driven into nonlinear regime
+and the response is measured by a displacement detector. For data analysis we
+introduce a nonlinear damping term to Duffing equation. The experiment shows
+conclusively that accounting for nonlinear damping effects is needed for
+correct modeling of the nanomechanical resonators under study.",0503130v2
+2006-05-23,The origin of increase of damping in transition metals with rare earth impurities,"The damping due to rare earth impurities in transition metals is discussed in
+the low concentration limit. It is shown that the increase in damping is mainly
+due to the coupling of the orbital moments of the rare earth impurities and the
+conduction $p$-electrons. It is shown that an itinerant picture for the host
+transition ions is needed to reproduce the observed dependence of the damping
+on the total angular moment of the rare earths.",0605583v1
+2001-05-14,Simplified models of electromagnetic and gravitational radiation damping,"In previous work the authors analysed the global properties of an approximate
+model of radiation damping for charged particles. This work is put into context
+and related to the original motivation of understanding approximations used in
+the study of gravitational radiation damping. It is examined to what extent the
+results obtained previously depend on the particular model chosen. Comparisons
+are made with other models for gravitational and electromagnetic fields. The
+relation of the kinetic model for which theorems were proved to certain
+many-particle models with radiation damping is exhibited.",0105045v1
+1994-06-07,Damping Rate of a Yukawa Fermion at Finite Temperature,"The damping of a massless fermion coupled to a massless scalar particle at
+finite temperature is considered using the Braaten-Pisarski resummation
+technique. First the hard thermal loop diagrams of this theory are extracted
+and effective Green's functions are constructed. Using these effective Green's
+functions the damping rate of a soft Yukawa fermion is calculated. This rate
+provides the most simple example for the damping of a soft particle. To leading
+order it is proportional to $g^2T$, whereas the one of a hard fermion is of
+higher order.",9406242v1
+2006-05-02,Moduli decay in the hot early Universe,"We consider moduli fields interacting with thermalized relativistic matter.
+We determine the temperature dependence of their damping rate and find it is
+dominated by thermal effects in the high temperature regime, i.e. for
+temperatures larger than their mass. For a simple scalar model the damping rate
+is expressed through the known matter bulk viscosity. The high temperature
+damping rate is always smaller than the Hubble rate, so that thermal effects
+are not sufficient for solving the cosmological moduli problem.",0605030v2
+2006-11-27,Inviscid limit for damped and driven incompressible Navier-Stokes equations in ${{\mathbb R}^2}$,"We consider the zero viscosity limit of long time averages of solutions of
+damped and driven Navier-Stokes equations in ${\mathbb R}^2$. We prove that the
+rate of dissipation of enstrophy vanishes. Stationary statistical solutions of
+the damped and driven Navier-Stokes equations converge to renormalized
+stationary statistical solutions of the damped and driven Euler equations.
+These solutions obey the enstrophy balance.",0611782v1
+2003-09-09,Traveling solitons in the damped driven nonlinear Schrödinger equation,"The well known effect of the linear damping on the moving nonlinear
+Schr\""odinger soliton (even when there is a supply of energy via the spatially
+homogeneous driving) is to quench its momentum to zero. Surprisingly, the zero
+momentum does not necessarily mean zero velocity. We show that two or more
+parametrically driven damped solitons can form a complex traveling with zero
+momentum at a nonzero constant speed.
+  All traveling complexes we have found so far, turned out to be unstable.
+Thus, the parametric driving is capable of sustaining the uniform motion of
+damped solitons, but some additional agent is required to stabilize it.",0309031v1
+2001-11-25,The Landau Damping Effect and Complex-valued Nature of Physical Quantities,"Within the framework of the hypothesis offered by authors about
+complex-valued nature of physical quantities, the effect of the Landau damping
+has been explored with assumption that not only frequency can be a small
+imaginary component but also a wave vector. The numerical solution of the
+obtained dispersion equation testifies that uncollisional damping is
+accompanied in a certain region of space by antidumping of waves, and in
+particular situations antidumping may prevail over damping. It is possible that
+this effect may explain the experimental difficulties connected with inhibition
+of instabilities of plasma in the problem of controllable thermonuclear fusion.",0111176v1
+2005-10-14,Nontrapping arrest of Langmuir wave damping near the threshold amplitude,"Evolution of a Langmuir wave is studied numerically for finite amplitudes
+slightly above the threshold which separates damping from nondamping cases.
+Arrest of linear damping is found to be a second-order effect due to ballistic
+evolution of perturbations, resonant power transfer between field and
+particles, and organization of phase space into a positive slope for the
+average distribution function $f_{av}$ around the resonant wave phase speed
+$v_\phi$. Near the threshold trapping in the wave potential does not arrest
+damping or saturate the subsequent growth phase.",0510131v3
+2000-06-22,Decoherence and Entanglement in Two-mode Squeezed Vacuum States,"I investigate the decoherence of two-mode squeezed vacuum states by analyzing
+the relative entropy of entanglement. I consider two sources of decoherence:
+(i) the phase damping and (ii) the amplitude damping due to the coupling to the
+thermal environment. In particular, I give the exact value of the relative
+entropy of entanglement for the phase damping model. For the amplitude damping
+model, I give an upper bound for the relative entropy of entanglement, which
+turns out to be a good approximation for the entanglement measure in usual
+experimental situations.",0006100v1
+2006-08-02,Damped Population Oscillation in a Spontaneously Decaying Two-Level Atom Coupled to a Monochromatic Field,"We investigate the time evolution of atomic population in a two-level atom
+driven by a monochromatic radiation field, taking spontaneous emission into
+account. The Rabi oscillation exhibits amplitude damping in time caused by
+spontaneous emission. We show that the semiclassical master equation leads in
+general to an overestimation of the damping rate and that a correct
+quantitative description of the damped Rabi oscillation can thus be obtained
+only with a full quantum mechanical theory.",0608020v1
+2007-08-28,Linear frictional forces cause orbits to neither circularize nor precess,"For the undamped Kepler potential the lack of precession has historically
+been understood in terms of the Runge-Lenz symmetry. For the damped Kepler
+problem this result may be understood in terms of the generalization of Poisson
+structure to damped systems suggested recently by Tarasov[1]. In this
+generalized algebraic structure the orbit-averaged Runge-Lenz vector remains a
+constant in the linearly damped Kepler problem to leading order in the damping
+coe",0708.3827v3
+2008-12-11,Frequency-dependent Drude damping in Casimir force calculations,"The Casimir force is calculated between Au thin films that are described by a
+Drude model with a frequency dependent damping function. The model parameters
+are obtained from available experimental data for Au thin films. Two cases are
+considered; annealed and nonannealed films that have a different damping
+function. Compared with the calculations using a Drude model with a constant
+damping parameter, we observe changes in the Casimir force of a few percent.
+This behavior is only observed in films of no more than 300 $\AA$ thick.",0812.2209v1
+2008-12-18,Dipole Oscillations of a Fermi Gas in a Disordered Trap: Damping and Localization,"We theoretically study the dipole oscillations of an ideal Fermi gas in a
+disordered trap. We show that even weak disorder induces strong damping of the
+oscillations and we identify a metal-insulator crossover. For very weak
+disorder, we show that damping results from a dephasing effect related to weak
+random perturbations of the energy spectrum. For increasing disorder, we show
+that the Fermi gas crosses over to an insulating regime characterized by
+strong-damping due to the proliferation of localized states.",0812.3501v2
+2009-03-11,Confronting the damping of the baryon acoustic oscillations with observation,"We investigate the damping of the baryon acoustic oscillations in the matter
+power spectrum due to the quasinonlinear clustering and redshift-space
+distortions by confronting the models with the observations of the Sloan
+Digital Sky Survey luminous red galaxy sample. The chi-squared test suggests
+that the observed power spectrum is better matched by models with the damping
+of the baryon acoustic oscillations rather than the ones without the damping.",0903.1883v1
+2009-04-10,Spectral deviations for the damped wave equation,"We prove a Weyl-type fractal upper bound for the spectrum of the damped wave
+equation, on a negatively curved compact manifold. It is known that most of the
+eigenvalues have an imaginary part close to the average of the damping
+function. We count the number of eigenvalues in a given horizontal strip
+deviating from this typical behaviour; the exponent that appears naturally is
+the `entropy' that gives the deviation rate from the Birkhoff ergodic theorem
+for the geodesic flow. A Weyl-type lower bound is still far from reach; but in
+the particular case of arithmetic surfaces, and for a strong enough damping, we
+can use the trace formula to prove a result going in this direction.",0904.1736v1
+2009-10-26,Pressure Fronts in 1D Damped Nonlinear Lattices,"The propagation of pressure fronts (impact solutions) in 1D chains of atoms
+coupled by anharmonic potentials between nearest neighbor and submitted to
+damping forces preserving uniform motion, is investigated. Travelling fronts
+between two regions at different uniform pressures are found numerically and
+well approximate analytically. It is proven that there are three analytical
+relations between the impact velocity, the compression, the front velocity and
+the energy dissipation which only depend on the coupling potential and are
+\textit{independent} of the damping. Such travelling front solutions cannot
+exist without damping.",0910.4890v1
+2009-11-05,Bloch oscillations in lattice potentials with controlled aperiodicity,"We numerically investigate the damping of Bloch oscillations in a
+one-dimensional lattice potential whose translational symmetry is broken in a
+systematic manner, either by making the potential bichromatic or by introducing
+scatterers at distinct lattice sites. We find that the damping strongly depends
+on the ratio of lattice constants in the bichromatic potential, and that even a
+small concentration of scatterers can lead to strong damping. Moreover,
+mean-field interactions are able to counteract aperiodicity-induced damping of
+Bloch oscillations.",0911.1108v3
+2010-01-12,Decoherence and damping in ideal gases,"The particle and current densities are shown to display damping and undergo
+decoherence in ideal quantum gases. The damping is read off from the equations
+of motion reminiscent of the Navier-Stokes equations and shows some formal
+similarity with Landau damping. The decoherence leads to consistent density and
+current histories with characteristic length and time scales given by the ideal
+gas.",1001.1803v2
+2010-05-14,The effect of spin magnetization in the damping of electron plasma oscillations,"The effect of spin of particles in the propagation of plasma waves is studied
+using a semi-classical kinetic theory for a magnetized plasma. We focus in the
+simple damping effects for the electrostatic wave modes besides Landau damping.
+Without taking into account more quantum effects than spin contribution to
+Vlasov's equation, we show that spin produces a new damping or instability
+which is proportional to the zeroth order magnetization of the system. This
+correction depends on the electromagnetic part of the wave which is coupled
+with the spin vector.",1005.2573v1
+2010-06-01,Recent Progress on a Manifold Damped and Detuned Structure for CLIC,"A damped detuned structure for the main X-band linacs of CLIC is being
+investigated as an alternative design to the present baseline heavily damped
+structure. In our earlier designs we studied detuned structures, operating at
+11.994 GHz, with a range of dipole bandwidths in order to ensure the structure
+satisfies beam dynamics and rf breakdown constraints. Here we report on the
+development of a damped and detuned structure which satisfies both constraints.
+Preparations for high power testing of the structure are also discussed",1006.0087v1
+2010-07-21,Finite temperature damping of collective modes of a BCS-BEC crossover superfluid,"A new mechanism is proposed to explain the puzzling damping of collective
+excitations, which was recently observed in the experiments of strongly
+interacting Fermi gases below the superfluid critical temperature on the
+fermionic (BCS) side of Feshbach resonance. Sound velocity, superfluid density
+and damping rate are calculated with effective field theory. We find that a
+dominant damping process is due to the interaction between superfluid phonons
+and thermally excited fermionic quasiparticles, in contrast to the previously
+proposed pair-breaking mechanism. Results from our effective model are compared
+quantitatively with recent experimental findings, showing a good agreement.",1007.3694v2
+2010-08-04,Confinement induced by fermion damping in three-dimensional QED,"The three-dimensional non-compact QED is known to exhibit weak confinement
+when fermions acquire a finite mass via the mechanism of dynamical chiral
+symmetry breaking. In this paper, we study the effect of fermion damping caused
+by elastic scattering on the classical potential between fermions. By
+calculating the vacuum polarization function that incorporates the fermion
+damping effect, we show that fermion damping can induce a weak confinement even
+when the fermions are massless and the chiral symmetry is not broken.",1008.0736v2
+2011-06-22,Highly Damped Quasinormal Modes and the Small Scale Structure of Quantum Corrected Black Hole Exteriors,"Quasinormal modes provide valuable information about the structure of
+spacetime outside a black hole. There is also a conjectured relationship
+between the highly damped quasinormal modes and the semi-classical spectrum of
+the horizon area/entropy. In this paper, we show that for spacetimes
+characterized by more than one scale, the ""infinitely damped"" modes in
+principle probe the structure of spacetime outside the horizon at the shortest
+length scales. We demonstrate this with the calculation of the highly damped
+quasinormal modes of the non-singular, single horizon, quantum corrected black
+hole derived in [14].",1106.4357v1
+2012-02-20,Simple Non-Markovian Microscopic Models for the Depolarizing Channel of a Single Qubit,"The archetypal one-qubit noisy channels ---depolarizing, phase-damping and
+amplitude-damping channels--- describe both Markovian and non-Markovian
+evolution. Simple microscopic models for the depolarizing channel, both
+classical and quantum, are considered. Microscopic models which describe phase
+damping and amplitude damping channels are briefly reviewed.",1202.4210v4
+2012-05-11,On radiative damping in plasma-based accelerators,"Radiative damping in plasma-based electron accelerators is analyzed. The
+electron dynamics under combined influence of the constant accelerating force
+and the classical radiation reaction force is studied. It is shown that
+electron acceleration cannot be limited by radiation reaction. If initially the
+accelerating force was stronger than the radiation reaction force then the
+electron acceleration is unlimited. Otherwise the electron is decelerated by
+radiative damping up to a certain instant of time and then accelerated without
+limits. Regardless of the initial conditions the infinite-time asymptotic
+behavior of an electron is governed by self-similar solution providing
+unlimited acceleration. The relative energy spread induced by the radiative
+damping decreases with time in the infinite-time limit.",1205.2436v1
+2012-06-14,Damping of optomechanical disks resonators vibrating in air,"We report on miniature GaAs disk optomechanical resonators vibrating in air
+in the radiofrequency range. The flexural modes of the disks are studied by
+scanning electron microscopy and optical interferometry, and correctly modeled
+with the elasticity theory for annular plates. The mechanical damping is
+systematically measured, and confronted with original analytical models for air
+damping. Formulas are derived that correctly reproduce both the mechanical
+modes and the damping behavior, and can serve as design tools for
+optomechanical applications in fluidic environment.",1206.3032v1
+2012-07-09,A Generalized Interpolation Inequality and its Application to the Stabilization of Damped Equations,"In this paper, we establish a generalized H{\""o}lder's or interpolation
+inequality for weighted spaces in which the weights are non-necessarily
+homogeneous. We apply it to the stabilization of some damped wave-like
+evolution equations. This allows obtaining explicit decay rates for smooth
+solutions for more general classes of damping operators. In particular, for
+$1-d$ models, we can give an explicit decay estimate for pointwise damping
+mechanisms supported on any strategic point.",1207.2030v2
+2012-07-10,Conformation dependent damping and generalization of fluctuation-dissipation relation,"Damping on an object generally depends on its conformation (shape size etc.).
+We consider the Langevin dynamics of a model system with a conformation
+dependent damping and generalize the fluctuation dissipation relation to fit in
+such a situation. We derive equilibrium distribution function for such a case
+which converges to the standard Boltzmann form at the limit of uniform damping.
+The results can have implications, in general, for barrier overcoming processes
+where standard Boltzmann statistics is slow.",1207.2218v2
+2012-10-30,On algebraic damping close to inhomogeneous Vlasov equilibria in multi-dimensional spaces,"We investigate the asymptotic damping of a perturbation around inhomogeneous
+stable stationary states of the Vlasov equation in spatially multi-dimensional
+systems. We show that branch singularities of the Fourier-Laplace transform of
+the perturbation yield algebraic dampings. In two spatial dimensions, we
+classify the singularities and compute the associated damping rate and
+frequency. This 2D setting also applies to spherically symmetric
+self-gravitating systems. We validate the theory using a toy model and an
+advection equation associated with the isochrone model, a model of spherical
+self-gravitating systems.",1210.8040v1
+2013-04-07,Phenomenological model of anomalous magnon softening and damping in half-metallic manganites,"To describe anomalous zone-boundary softening and damping of magnons in
+manganites we present a phenomenological two-fluid model containing
+ferromagnetic Fermi-liquid and non-Fermi-liquid components. The Fermi-liquid
+component accounts for softening of zone-boundary magnons and for the Landau
+damping of magnons in the Stoner continuum arising at low frequencies due to
+zero-point effects. Coupling of the Fermi-liquid and non-Fermi-liquid fluids
+yields conventional long wavelength magnons damped due to their coupling with
+longitudinal spin fluctuations.",1304.1983v1
+2013-04-25,Determination of Transverse Density Structuring from Propagating MHD Waves in the Solar Atmosphere,"We present a Bayesian seismology inversion technique for propagating
+magnetohydrodynamic (MHD) transverse waves observed in coronal waveguides. The
+technique uses theoretical predictions for the spatial damping of propagating
+kink waves in transversely inhomogeneous coronal waveguides. It combines wave
+amplitude damping length scales along the waveguide with theoretical results
+for resonantly damped propagating kink waves to infer the plasma density
+variation across the oscillating structures. Provided the spatial dependence of
+the velocity amplitude along the propagation direction is measured and the
+existence of two different damping regimes is identified, the technique would
+enable us to fully constrain the transverse density structuring, providing
+estimates for the density contrast and its transverse inhomogeneity length
+scale.",1304.6869v1
+2013-07-08,Optimal decay rate of the bipolar Euler-Poisson system with damping in $\mathbb{R}^3$,"By rewriting a bipolar Euler-Poisson equations with damping into an Euler
+equation with damping coupled with an Euler-Poisson equation with damping, and
+using a new spectral analysis, we obtain the optimal decay results of the
+solutions in $L^2$-norm, which improve theose in \cite{Li3, Wu3}. More
+precisely, the velocities $u_1,u_2$ decay at the $L^2-$rate $(1+t)^{-{5}{4}}$,
+which is faster than the normal $L^2-$rate $(1+t)^{-{3}{4}}$ for the Heat
+equation and the Navier-Stokes equations. In addition, the disparity of two
+densities $\rho_1-\rho_2$ and the disparity of two velocities $u_1-u_2$ decay
+at the $L^2$-rate $(1+t)^{-2}$.",1307.2081v1
+2013-07-27,Symmetry considerations on radiation damping,"It is well known that a direct Lagrangian description of radiation damping is
+still missing. In this paper we will use a specific approach of this problem
+which is the standard way to treat the radiation damping problem. The
+objectives here are to construct: a N=2 supersymmetric extension for the model
+describing the radiation damping on the noncommutative plane with electric and
+magnetic interactions; a dualization analysis of the original action; the
+supercharge algebra and the total Hamiltonian for the system.",1307.7319v1
+2014-02-10,Damping of a nanocantilever by paramagnetic spins,"We compute damping of mechanical oscillations of a cantilever that contains
+flipping paramagnetic spins. This kind of damping is mandated by the dynamics
+of the total angular momentum, spin + mechanical. Rigorous expression for the
+damping rate is derived in terms of measurable parameters. The effect of spins
+on the quality factor of the cantilever can be significant in cantilevers of
+small length that have large concentration of paramagnetic spins of atomic
+and/or nuclear origin.",1402.2326v1
+2014-02-20,Long-time behavior of solutions of a BBM equation with generalized damping,"We study the long-time behavior of the solution of a damped BBM equation $u_t
++ u_x - u_{xxt} + uu_x + \mathscr{L}_{\gamma}(u) = 0$. The proposed dampings
+$\mathscr{L}_{\gamma}$ generalize standards ones, as parabolic
+($\mathscr{L}_{\gamma}(u)=-\Delta u$) or weak damping
+($\mathscr{L}_{\gamma}(u)=\gamma u$) and allows us to consider a greater range.
+After establish the local well-posedness in the energy space, we investigate
+some numerical properties.",1402.5009v1
+2014-02-24,N=2 supersymmetric radiation damping problem on a noncommutative plane,"It is well known that a direct Lagrangian description of radiation damping is
+still missing. In this paper a specific approach of this problem was used,
+which is the standard way to treat the radiation damping problem. A $N=2$
+supersymmetric extension for the model describing the radiation damping on the
+noncommutative plane with electric and magnetic interactions was obtained. The
+entire supercharge algebra and the total Hamiltonian for the system were
+analyzed. Finally, noncommutativity features were introduced and its
+consequences were explored..",1402.6996v1
+2014-11-03,Renormalized solutions to the continuity equation with an integrable damping term,"We consider the continuity equation with a nonsmooth vector field and a
+damping term. In their fundamental paper, DiPerna and Lions proved that, when
+the damping term is bounded in space and time, the equation is well posed in
+the class of distributional solutions and the solution is transported by
+suitable characteristics of the vector field. In this paper, we prove existence
+and uniqueness of renormalized solutions in the case of an integrable damping
+term, employing a new logarithmic estimate inspired by analogous ideas of
+Ambrosio, Lecumberry, and Maniglia, Crippa and De Lellis in the Lagrangian
+case.",1411.0451v1
+2015-02-07,Landau Damping in a Mixture of Bose and Fermi Superfluids,"We study the Landau damping in Bose-Fermi superfluid mixture at finite
+temperature. We find that at low temperature, the Landau damping rate will be
+exponentially suppressed at both the BCS side and the BEC side of Fermi
+superfluid. The momentum dependence of the damping rate is obtained, and it is
+quite different from the BCS side to the BEC side. The relations between our
+result and collective mode experiment in the recently realized Bose-Fermi
+superfluid mixture are also discussed.",1502.02116v1
+2015-03-20,Applying a formula for generator redispatch to damp interarea oscillations using synchrophasors,"If an interarea oscillatory mode has insufficient damping, generator
+redispatch can be used to improve its damping. We explain and apply a new
+analytic formula for the modal sensitivity to rank the best pairs of generators
+to redispatch. The formula requires some dynamic power system data and we show
+how to obtain that data from synchrophasor measurements. The application of the
+formula to damp interarea modes is explained and illustrated with interarea
+modes of the New England 10-machine power system.",1503.06144v2
+2016-01-21,Codeword Stabilized Quantum Codes for Asymmetric Channels,"We discuss a method to adapt the codeword stabilized (CWS) quantum code
+framework to the problem of finding asymmetric quantum codes. We focus on the
+corresponding Pauli error models for amplitude damping noise and phase damping
+noise. In particular, we look at codes for Pauli error models that correct one
+or two amplitude damping errors. Applying local Clifford operations on graph
+states, we are able to exhaustively search for all possible codes up to length
+$9$. With a similar method, we also look at codes for the Pauli error model
+that detect a single amplitude error and detect multiple phase damping errors.
+Many new codes with good parameters are found, including nonadditive codes and
+degenerate codes.",1601.05763v1
+2016-02-08,On Boundary Damped Inhomogeneous Timoshenko Beams and Related Problems,"We consider the model equations for the Timoshenko beam as a first order
+system in the framework of evolutionary equations. The focus is on boundary
+damping, which is implemented as a dynamic boundary condition. A change of
+material laws allows to include a large class of cases of boundary damping. By
+choosing a particular material law, it is shown that the first order approach
+to Sturm-Liouville problems with boundary damping is also covered.",1602.02521v1
+2016-02-13,Diffusion phenomena for the wave equation with space-dependent damping in an exterior domain,"In this paper, we consider the asymptotic behavior of solutions to the wave
+equation with space-dependent damping in an exterior domain. We prove that when
+the damping is effective, the solution is approximated by that of the
+corresponding heat equation as time tends to infinity. Our proof is based on
+semigroup estimates for the corresponding heat equation and weighted energy
+estimates for the damped wave equation. The optimality of the decay late for
+solutions is also established.",1602.04318v1
+2016-02-29,Robust quantum state recovery from amplitude damping within a mixed states framework,"Due to the interaction with the environment, a quantum state is subjected to
+decoherence which becomes one of the biggest problems for practical quantum
+computation. Amplitude damping is one of the most important decoherence
+processes. Here, we show that general two-qubit mixed states undergoing an
+amplitude damping can be almost completely restored using a reversal procedure.
+This reversal procedure through CNOT and Hadamard gates, could also protect the
+entanglement of two-qubit mixed states, when it undergoes general amplitude
+damping. Moreover, in the presence of uncertainty in the underlying system, we
+propose a robust recovering method with optimal characteristics of the problem.",1602.08865v1
+2016-05-23,Large time behaivor of global solutions to nonlinear wave equations with frictional and viscoelastic damping terms,"In this paper, we study the Cauchy problem for a nonlinear wave equation with
+frictional and viscoelastic damping terms. As is pointed out by [8], in this
+combination, the frictional damping term is dominant for the viscoelastic one
+for the global dynamics of the linear equation. In this note we observe that if
+the initial data is small, the frictional damping term is again dominant even
+in the nonlinear equation case. In other words, our main result is diffusion
+phenomena: the solution is approximated by the heat kernel with a suitable
+constant. Our proof is based on several estimates for the corresponding linear
+equations.",1605.07232v1
+2016-07-21,Protecting and enhancing spin squeezing under decoherence using weak measurement,"We propose an efficient method to protect spin squeezing under the action of
+amplitude-damping, depolarizing and phase-damping channels based on measurement
+reversal from weak measurement, and consider an ensemble of N independent
+spin-1/2 particles with exchange symmetry. We find that spin squeezing can be
+enhanced greatly under three different decoherence channels and spin-squeezing
+sudden death (SSSD) can be avoided undergoing amplitude damping and
+phase-damping channels.",1607.06530v2
+2016-11-16,Finite-orbit-width effects on the geodesic acoustic mode in the toroidally rotating tokamak plasma,"The Landau damping of geodesic acoustic mode (GAM) in a torodial rotating
+tokamak plasma is analytically investigated by taking into account the
+finite-orbit-width (FOW) resonance effect to the 3rd order. The analytical
+result is shown to agree well with the numerical solution. The dependence of
+the damping rate on the toroidal Mach number $M$ relies on $k_r \rho_i$. For
+sufficiently small $k_r \rho_i$, the damping rate monotonically decreases with
+$M$. For relatively large $k_r \rho_i$, the damping rate increases with $M$
+until approaching the maximum and then decreases with $M$.",1611.05168v1
+2017-04-21,The Effects of Rolling Deformation and Annealing Treatment on Damping Capacity of 1200 Aluminium Alloy,"Annealing treatment is an important step of rolling deformation that
+contributes to microstructural evolution and leads to the significant changes
+in damping capacity. Damping capacities were analyzed in the parallel to
+rolling direction at 1 and 10 Hz respectively. It was found that severe plastic
+deformation at 40 percent reduction has lower damping capacity compared to that
+of 30 percent and 20 percent reductions respectively. The microstructural
+results show that the grains of as rolled alloys were changed to almost
+equiaxed structures after a rolling reduction at 40 percent reduction.",1704.07362v1
+2017-07-12,Isolated resonances and nonlinear damping,"We analyze isolated resonance curves (IRCs) in a single-degree-of-freedom
+system with nonlinear damping. The adopted procedure exploits singularity
+theory in conjunction with the harmonic balance method. The analysis unveils a
+geometrical connection between the topology of the damping force and IRCs.
+Specifically, we demonstrate that extremas and zeros of the damping force
+correspond to the appearance and merging of IRCs.",1707.03561v2
+2017-07-25,Best exponential decay rate of energy for the vectorial damped wave equation,"The energy of solutions of the scalar damped wave equation decays uniformly
+exponentially fast when the geometric control condition is satisfied. A theorem
+of Lebeau [leb93] gives an expression of this exponential decay rate in terms
+of the average value of the damping terms along geodesics and of the spectrum
+of the infinitesimal generator of the equation. The aim of this text is to
+generalize this result in the setting of a vectorial damped wave equation on a
+Riemannian manifold with no boundary. We obtain an expression analogous to
+Lebeau's one but new phenomena like high frequency overdamping arise in
+comparison to the scalar setting. We also prove a necessary and sufficient
+condition for the strong stabilization of the vectorial wave equation.",1707.07893v1
+2017-08-20,Radiation Damping of a Polarizable Particle,"A polarizable body moving in an external electromagnetic field will slow
+down. This effect is referred to as radiation damping and is analogous to
+Doppler cooling in atomic physics. Using the principles of special relativity
+we derive an expression for the radiation damping force and find that it solely
+depends on the scattered power. The cooling of the particle's center-of-mass
+motion is balanced by heating due to radiation pressure shot noise, giving rise
+to an equilibrium that depends on the ratio of the field's frequency and the
+particle's mass. While damping is of relativistic nature heating has it's roots
+in quantum mechanics.",1708.06628v1
+2017-09-13,Energy decay for the Klein-Gordon equation with highly oscillating damping,"We consider the free Klein-Gordon equation with periodic damping. We show on
+this simple model that if the usual geometric condition holds then the decay of
+the energy is uniform with respect to the oscillations of the damping, and in
+particular the size of the derivatives do not play any role. We also show that
+without geometric condition the polynomial decay of the energy is even slightly
+better for a highly oscillating damping. To prove these estimates we provide a
+parameter dependent version of well known results of semigroup theory.",1709.04197v1
+2017-11-01,Analysis of A Splitting Scheme for Damped Stochastic Nonlinear Schrödinger Equation with Multiplicative Noise,"In this paper, we investigate the damped stochastic nonlinear
+Schr\""odinger(NLS) equation with multiplicative noise and its splitting-based
+approximation. When the damped effect is large enough, we prove that the
+solutions of the damped stochastic NLS equation and the splitting scheme are
+exponential stable and possess some exponential integrability.
+  These properties lead that the strong order of the scheme is $\frac 12$ and
+independent of time. Meanwhile, we analyze the regularity of the Kolmogorov
+equation with respect to the equation. As a consequence, the weak order of the
+scheme is shown to be twice the strong order and independent of time.",1711.00516v2
+2017-12-31,Stabilization of the weakly coupled wave-plate system with one internal damping,"This paper is addressed to a stabilization problem of a system coupled by a
+wave and a Euler-Bernoulli plate equation. Only one equation is supposed to be
+damped. Under some assumption about the damping and the coupling terms, it is
+shown that sufficiently smooth solutions of the system decay logarithmically at
+infinity without any geometric conditions on the effective damping domain. The
+proofs of these decay results rely on the interpolation inequalities for the
+coupled elliptic-parabolic systems and make use of the estimate of the
+resolvent operator for the coupled system. The main tools to derive the desired
+interpolation inequalities are global Carleman estimates.",1801.00232v1
+2018-05-10,Dynamics of coherence-induced state ordering under Markovian channels,"We study the dynamics of coherence-induced state ordering under incoherent
+channels, particularly four specific Markovian channels: $-$ amplitude damping
+channel, phase damping channel, depolarizing channel and bit flit channel for
+single-qubit states. We show that the amplitude damping channel, phase damping
+channel, and depolarizing channel do not change the coherence-induced state
+ordering by $l_1$ norm of coherence, relative entropy of coherence, geometric
+measure of coherence, and Tsallis relative $\alpha$-entropies, while the bit
+flit channel does change for some special cases.",1805.03898v1
+2018-08-19,Sharp lifespan estimates of blowup solutions to semilinear wave equations with time-dependent effective damping,"We consider the initial value problem for the semilinear wave equation with
+time-dependent effective damping. The interest is the behavior of lifespan of
+solutions in view of the asymptotic profile of the damping as $t\to \infty$.
+The result of this paper is the sharp lifespan estimates of blowup solutions
+for general time-dependent damping including threshold cases between effective
+and overdamping.",1808.06189v2
+2018-09-05,Damping estimates for oscillatory integral operators with real-analytic phases and its applications,"In this paper, we investigate sharp damping estimates for a class of one
+dimensional oscillatory integral operators with real-analytic phases. By
+establishing endpoint estimates for suitably damped oscillatory integral
+operators, we are able to give a new proof of the sharp $L^p$ estimates which
+have been proved by Xiao in Endpoint estimates for one-dimensional oscillatory
+integral operators, \emph{Advances in Mathematics}, \textbf{316}, 255-291
+(2017). The damping estimates obtained in this paper are of independent
+interest.",1809.01298v2
+2018-09-26,"Global Attractor For Weakly Damped, Forced Mkdv Equation Below Energy Space","We prove the existence of the global attractor in $ \dot H^s$, $s > 11/12$
+for the weakly damped and forced mKdV on the one dimensional torus. The
+existence of global attractor below the energy space has not been known, though
+the global well-posedness below the energy space is established. We directly
+apply the I-method to the damped and forced mKdV, because the Miura
+transformation does not work for the mKdV with damping and forcing terms. We
+need to make a close investigation into the trilinear estimates involving
+resonant frequencies, which are different from the bilinear estimates
+corresponding to the KdV.",1809.09787v1
+2018-10-03,Damped Oscillator with delta-kicked frequency in probability representation of quantum mechanic,"We obtain the tomogram of squeezed correlated states of a quantum parametric
+damped oscillator in an explicit form. We study the damping within the
+framework of the Caldirola--Kanai model and chose the parametric excitation in
+the form of a very short pulse simulated by a delta-kick of frequency; the
+squeezing phenomenon is reviewed. The cases of strong and weak damping are
+investigated.",1810.01672v1
+2018-10-26,Drastic Reduction of Plasmon Damping in Two-Dimensional Electron Disks,"The plasmon damping has been investigated using resonant microwave absorption
+of two-dimensional electrons in disks with different diameters. We have found
+an unexpected drastic reduction of the plasmon damping in the regime of strong
+retardation. This finding implies large delocalization of retarded plasmon
+field outside the plane of the two-dimensional electron system. A universal
+relation between the damping of plasmon polariton waves and retardation
+parameter is reported.",1811.01040v1
+2019-01-05,Cauchy problem for thermoelastic plate equations with different damping mechanisms,"In this paper we study Cauchy problem for thermoelastic plate equations with
+friction or structural damping in $\mathbb{R}^n$, $n\geq1$, where the heat
+conduction is modeled by Fourier's law. We explain some qualitative properties
+of solutions influenced by different damping mechanisms. We show which damping
+in the model has a dominant influence on smoothing effect, energy estimates,
+$L^p-L^q$ estimates not necessary on the conjugate line, and on diffusion
+phenomena. Moreover, we derive asymptotic profiles of solutions in a framework
+of weighted $L^1$ data. In particular, sharp decay estimates for lower bound
+and upper bound of solutions in the $\dot{H}^s$ norm ($s\geq0$) are shown.",1901.01423v2
+2019-03-04,Damping of cosmological tensor modes in Horndeski theories after GW170817,"This paper investigates the propagation of cosmological gravitational waves
+interacting with free-streaming neutrinos within the context of Horndeski
+theories of gravity constrained by the detection of GW170817. We apply the
+theory of cosmological perturbations to explicitly derive the
+Einstein-Boltzmann equation for the damped propagation of first-order
+transverse traceless gravitational waves. In contrast to general relativity, we
+argue that modified gravity can give rise to non-vanishing free-streaming
+damping effects during the cosmological matter dominated era. We also provide
+an analytic formula for the main multipole order with which modified gravity
+and free-streaming neutrinos damp the variety of tensor correlation functions
+of the cosmic microwave background.",1903.01502v2
+2019-08-22,Damping of the Anderson-Bogolyubov mode by spin and mass imbalance in Fermi mixtures,"We study the temporally nonlocal contributions to the gradient expansion of
+the pair fluctuation propagator for spin- and mass-imbalanced Fermi mixtures.
+These terms are related to damping processes of sound-like
+(Anderson-Bogolyubov) collective modes and are relevant for the structure of
+the complex pole of the pair fluctuation propagator. We derive conditions under
+which damping occurs even at zero temperature for large enough mismatch of the
+Fermi surfaces. We compare our analytical results with numerically computed
+damping rates of the Anderson-Bogolyubov mode.",1908.08559v2
+2019-11-05,On the Smallness Condition in Linear Inviscid Damping: Monotonicity and Resonance Chains,"We consider the linearized Euler equations around a smooth, bilipschitz shear
+profile $U(y)$ on $\mathbb{T}_L \times \mathbb{R}$. We construct an explicit
+flow which exhibits linear inviscid damping for $L$ sufficiently small, but for
+which damping fails if $L$ is large. In particular, similar to the instability
+results for convex profiles for a shear flow being bilipschitz is not
+sufficient for linear inviscid damping to hold. Instead of an eigenvalue-based
+argument the underlying mechanism here is shown to be based on a new cascade of
+resonances moving to higher and higher frequencies in $y$, which is distinct
+from the echo chain mechanism in the nonlinear problem.",1911.02066v1
+2020-01-02,On Echo Chains in Landau damping: Self-similar Solutions and Gevrey 3 as a Linear Stability Threshold,"We show that the linearized Vlasov-Poisson equations around self-similar
+non-homogeneous states near zero contain the full plasma echo mechanism,
+yielding Gevrey 3 as a critical stability class. Moreover, here Landau damping
+may persist despite blow-up: We construct a critical Gevrey regularity class in
+which the force field converges in $L^2$. Thus, on the one hand, the physical
+phenomenon of Landau damping holds. On the other hand, the density diverges to
+infinity in Sobolev regularity. Hence, ``strong damping'' cannot hold.",2001.00513v1
+2020-01-21,Pseudospectra of the damped wave equation with unbounded damping,"We analyze pseudospectra of the generator of the damped wave equation with
+unbounded damping. We show that the resolvent norm diverges as $\Re z \to -
+\infty$. The highly non-normal character of the operator is a robust effect
+preserved even when a strong potential is added. Consequently, spectral
+instabilities and other related pseudospectral effects are present.",2001.07767v1
+2020-02-09,The damped wave equation with singular damping,"We analyze the spectral properties and peculiar behavior of solutions of a
+damped wave equation on a finite interval with a singular damping of the form
+$\alpha/x$, $\alpha>0$. We establish the exponential stability of the semigroup
+for all positive $\alpha$, and determine conditions for the spectrum to consist
+of a finite number of eigenvalues. As a consequence, we fully characterize the
+set of initial conditions for which there is extinction of solutions in finite
+time. Finally, we propose two open problems related to extremal decay rates of
+solutions.",2002.03440v1
+2020-03-12,Optimal nonlinear damping control of second-order systems,"Novel nonlinear damping control is proposed for the second-order systems. The
+proportional output feedback is combined with the damping term which is
+quadratic to the output derivative and inverse to the set-point distance. The
+global stability, passivity property, and convergence time and accuracy are
+demonstrated. Also the control saturation case is explicitly analyzed. The
+suggested nonlinear damping is denoted as optimal since requiring no design
+additional parameters and ensuring a fast convergence, without transient
+overshoots for a non-saturated and one transient overshoot for a saturated
+control configuration.",2003.05670v3
+2020-11-11,Reduction of back switching by large damping ferromagnetic material,"Recent studies on magnetization dynamics induced by spin-orbit torque have
+revealed a weak dependence of the critical current for magnetization switching
+on the damping constant of a ferromagnetic free layer. This study, however,
+reveals that the damping constant nevertheless plays a key role in
+magnetization switching induced by spin-orbit torque. An undesirable switching,
+returning to an initial state, named as back switching, occurs in a ferromagnet
+with an easy axis parallel to the current direction. Numerical and theoretical
+analyses reveal that back switching is strongly suppressed when the damping
+constant of the ferromagnet is large.",2011.05566v1
+2020-12-28,Nonlinear modal analysis of nonconservative systems: Extension of the periodic motion concept,"As the motions of nonconservative autonomous systems are typically not
+periodic, the definition of nonlinear modes as periodic motions cannot be
+applied in the classical sense. In this paper, it is proposed 'make the motions
+periodic' by introducing an additional damping term of appropriate sign and
+magnitude. It is shown that this generalized definition is particularly suited
+to reflect the periodic vibration behavior induced by harmonic external forcing
+or negative linear damping. In a large range, the energy dependence of modal
+frequency, damping ratio and stability is reproduced well. The limitation to
+isolated or weakly-damped modes is discussed.",2101.00949v1
+2021-04-12,Lp-asymptotic stability of 1D damped wave equations with localized and linear damping,"In this paper, we study the $L^p$-asymptotic stability of the one-dimensional
+linear damped wave equation with Dirichlet boundary conditions in $[0,1]$, with
+$p\in (1,\infty)$. The damping term is assumed to be linear and localized to an
+arbitrary open sub-interval of $[0,1]$. We prove that the semi-group
+$(S_p(t))_{t\geq 0}$ associated with the previous equation is well-posed and
+exponentially stable. The proof relies on the multiplier method and depends on
+whether $p\geq 2$ or $1<p<2$.",2104.05679v1
+2021-05-13,Sharp Polynomial Decay for Waves Damped from the Boundary in Cylindrical Waveguides,"We study the decay of global energy for the wave equation with H\""older
+continuous damping placed on the $C^{1,1}$-boundary of compact and non-compact
+waveguides with star-shaped cross-sections. We show there is sharp
+$t^{-1/2}$-decay when the damping is uniformly bounded from below on the
+cylindrical wall of product cylinders where the Geometric Control Condition is
+violated. On non-product cylinders, we also show that there is $t^{-1/3}$-decay
+when the damping is uniformly bounded from below on the cylindrical wall.",2105.06566v1
+2021-06-02,Stabilisation of the generalised Rao-Nakra beam by partial viscous damping,"In this paper, we consider the stabilization of the generalized Rao-Nakra
+beam equation, which consists of four wave equations for the longitudinal
+displacements and the shear angle of the top and bottom layers and one
+Euler-Bernoulli beam equation for the transversal displacement. Dissipative
+mechanism are provided through viscous damping for two displacements. The
+location of the viscous damping are divided into two groups, characterized by
+whether both of the top and bottom layers are directly damped or otherwise.
+Each group consists of three cases. We obtain the necessary and sufficient
+conditions for the cases in group two to be strongly stable. Furthermore,
+polynomial stability of certain orders are proved. The cases in group one are
+left for future study",2106.01189v1
+2021-09-01,Vibration damping platform for cavity quantum-electrodynamics experiments,"We present a mechanical platform with enhanced vibration damping properties
+for cavity quantum-electrodynamics experiments. It is based on a composite
+design that combines a soft, vibration-damping core with a rigid shell
+maintaining optical alignment. It passively damps the vibrations generated by
+piezoelectric actuators controlling the mirror positions. The mechanical
+resonances of the platform, which lead to a length change of the cavity are
+efficiently suppressed up to 100 kHz. Our platform is ultra-high vacuum
+compatible and can be used in most applications, in particular where long
+cavities and optical access to the cavity center are required.",2109.00439v1
+2021-09-05,"Existence of a generalized polynomial attractor for the wave equation with nonlocal weak damping, anti-damping and critical nonlinearity","In this paper, we first establish a criterion based on contractive function
+for the existence of polynomial attractors. This criterion only involves some
+rather weak compactness associated with the repeated limit inferior and
+requires no compactness, which makes it suitable for critical cases. Then by
+this abstract theorem, we verify the existence of a polynomial attractor and
+estimate its attractive speed for the wave equation with nonlocal weak damping,
+anti-damping and critical nonlinearity.",2109.01967v2
+2021-11-29,Stabilization of coupled wave equations with viscous damping on cylindrical and non-regular domains: Cases without the geometric control condition,"In this paper, we investigate the direct and indirect stability of locally
+coupled wave equations with local viscous damping on cylindrical and
+non-regular domains without any geometric control condition. If only one
+equation is damped, we prove that the energy of our system decays polynomially
+with the rate $t^{-\frac{1}{2}}$ if the two waves have the same speed of
+propagation, and with rate $t^{-\frac{1}{3}}$ if the two waves do not propagate
+at the same speed. Otherwise, in case of two damped equations, we prove a
+polynomial energy decay rate of order $t^{-1}$.",2111.14554v1
+2022-01-25,Linear pair creation damping of high frequency plasma oscillation,"We have studied the linear dispersion relation for Langmuir waves in plasmas
+of very high density, based on the Dirac-Heisenberg-Wigner formalism. The
+vacuum contribution to the physical observables leads to ultra-violet
+divergences, that are removed by a charge renormalization. The remaining vacuum
+contribution is small, and is in agreement with previously derived expressions
+for the time-dependent vacuum polarization. The main new feature of the theory
+is a damping mechanism similar to Landau damping, but where the plasmon energy
+give rise to creation of electron-positron pairs. The dependence of the damping
+rate (pair-creation rate) on wave-number, temperature, and density is analyzed.
+Finally, the analytical results of linearized theory are compared.",2201.10370v1
+2022-03-13,Continuum damping of topologically-protected edge modes at the boundary of a magnetized plasma,"Recent extension of the topological ideas to continuous systems with broken
+time-reversal symmetry, such as magnetized plasmas, provides new insights into
+the nature of scattering-free topologically-protected surface plasma waves
+(TSPWs). We demonstrate a unique characteristic of TSPWs propagating above the
+electron cyclotron frequency: their collisionless damping via coupling to the
+continuum of resonant modes localized inside a smooth plasma-vacuum interface.
+Damped TSPWs retain their unidirectional nature and robustness against
+backscattering. When sheared magnetic field creates a boundary between damped
+and undamped TSPWs, the two refract into each other without reflections",2203.06693v2
+2022-04-21,On scattering and damping of Toroidal Alfven eigenmode by drift wave turbulence,"We demonstrate analytically that, in toroidal plasmas, scattering by drift
+wave turbulence could lead to appreciable damping of toroidal Alfven eigenmodes
+via generation of short-wavelength electron Landau damped kinetic Alfven waves.
+A corresponding analytic expression of the damping rate is derived, and found
+to be, typically, comparable to the linear drive by energetic particles. The
+implications of this novel mechanism on the transport and heating processes in
+burning plasmas are also discussed.",2204.09876v1
+2023-07-11,Global smooth solution for the 3D generalized tropical climate model with partial viscosity and damping,"The three-dimensional generalized tropical climate model with partial
+viscosity and damping is considered in this paper. Global well-posedness of
+solutions of the three-dimensional generalized tropical climate model with
+partial viscosity and damping is proved for $\alpha\geq\frac{3}{2}$ and
+$\beta\geq4$. Global smooth solution of the three-dimensional generalized
+tropical climate model with partial viscosity and damping is proved in
+$H^s(\mathbb R^3)$ $(s>2)$ for $\alpha\geq\frac{3}{2}$ and $4\leq\beta\leq5$.",2307.05145v3
+2023-08-07,Reconstruction of the initial data from the solutions of damped wave equations,"In this paper, we consider two types of damped wave equations: the weakly
+damped equation and the strongly damped equation and show that the initial
+velocity from the solution on the unit sphere. This inverse problem is related
+to Photoacoustic Tomography (PAT), a hybrid medical imaging technique. PAT is
+based on generating acoustic waves inside of an object of interest and one of
+the mathematical problem in PAT is reconstructing the initial velocity from the
+solution of the wave equation measured on the outside of object. Using the
+spherical harmonics and spectral theorem, we demonstrate a way to recover the
+initial velocity.",2308.03362v1
+2023-09-26,Sharp conditions for exponential and non-exponential uniform stabilization of the time dependent damped wave equation,"It is classical that uniform stabilization of solutions to the damped wave
+equation is equivalent to the geometric control condition The author previously
+showed that, when the damping depends on time, a generalization of the
+geometric control condition implies uniform stabilization at an exponential
+rate. In this paper, it is shown that this generalization of the geometric
+control condition is necessary for uniform stabilization at an exponential
+rate. Furthermore, when the damping does not satisfy this generalization, and
+has some additional structure, upper and lower bounds on non-exponential
+uniform stabilization are computed. The qualitative behavior of these upper and
+lower bounds coincide.",2309.15005v1
+2023-10-19,The damped focusing cubic wave equation on a bounded domain,"For the focusing cubic wave equation on a compact Riemannian manifold of
+dimension $3$, the dichotomy between global existence and blow-up for solutions
+starting below the energy of the ground state is known since the work of Payne
+and Sattinger. In the case of a damped equation, we prove that the dichotomy
+between global existence and blow-up still holds. In particular, the damping
+does not prevent blow-up. Assuming that the damping satisfies the geometric
+control condition, we then prove that any global solution converges to a
+stationary solution along a time sequence, and that global solutions below the
+energy of the ground state can be stabilised, adapting the proof of a similar
+result in the defocusing case.",2310.12644v2
+2024-04-03,Damping Reveals Hidden Dimensions in Elastic Metastructures Through Induced Transparency,"Damping typically results in attenuation of vibrations and elastic wave
+propagation in mechanical systems. Contrary to this conventional understanding,
+we demonstrate experimentally and explain theoretically the revival of an
+elastic wave transmitted through a periodic metastructure when a weak
+non-Hermitian defect (damping mechanism) induces violation of time-reversal
+symmetry. Damping alters the nature of the system's resonant modes, instigating
+interference in the scattering field. This leads to transmission revival,
+revealing the presence of hidden modes which are otherwise masked by the
+symmetry. Our findings offer an innovative approach for designing
+dissipation-driven switches and controllers and non-destructive structural
+health monitoring systems.",2404.02979v1
+1997-06-30,Damped Lyman Alpha Systems at High Redshift and Models of Protogalactic Disks,"We employ observationally determined intrinsic velocity widths and column
+densities of damped Lyman-alpha systems at high redshift to investigate the
+distribution of baryons in protogalaxies within the context of a standard cold
+dark matter model. We proceed under the assumption that damped Lyman alpha
+systems represent a population of cold, rotationally supported, protogalactic
+disks and that the abundance of protogalactic halos is well approximated by a
+cold dark matter model with critical density and vanishing cosmological
+constant. Using conditional cross sections to observe a damped system with a
+given velocity width and column density, we compare observationally inferred
+velocity width and column density distributions to the corresponding
+theoretically determined distributions for a variety of disk parameters and CDM
+normalizations. In general, we find that the observations can not be reproduced
+by the models for most disk parameters and CDM normalizations. Whereas the
+column density distribution favors small disks with large neutral gas fraction,
+the velocity width distribution favors large and thick disks with small neutral
+gas fraction. The possible resolutions of this problem in the context of this
+CDM model may be: (1) an increased contribution of rapidly rotating disks
+within massive dark matter halos to damped Lyman-alpha absorption or (2) the
+abandoning of simple disk models within this CDM model for damped Lyman-alpha
+systems at high redshift. Here the first possibility may be achieved by
+supposing that damped Lya system formation only occurs in halos with fairly
+large circular velocities and the second possibility may result from a large
+contribution of mergers and double-disks to damped Lya absorption at high
+redshift.",9706290v1
+2000-03-16,Non-existence of radiation damping of gravitational motions,"A rigorous, non-perturbative proof that there is no radiation damping of
+gravitational motions.",0003230v1
+2006-07-14,Lagrangian description of the radiation damping,"We present a Lagrangian formalism to the dissipative system of a charge
+interacting with its own radiation field, which gives rise to the radiation
+damping \cite{Heitler}, by the indirect representation doubling the phase-space
+dimensions.",0607370v1
+1994-05-17,Damping Rate of a Hard Photon in a Relativistic Plasma,"The damping rate of a hard photon in a hot relativistic QED and QCD plasma is
+calculated using the resummation technique by Braaten and Pisarski.",9405309v1
+1998-04-08,Evidence for xi- and t-dependent damping of the Pomeron Flux in the proton,"We show that a triple-Regge parametrization of inclusive single diffraction
+agrees with the data in the following two domains: (a) xi > 0.03 at all t, (b)
+|t| > 1 GeV^2 at all xi. Since the triple-Regge parametrization fails when
+applied to the full xi-t range of the total single-diffractive cross section,
+we conclude that damping occurs only at low-xi and low-|t|. We give a (``toy'')
+parametrization of the damping factor, D(xi), valid at low-|t|, which describes
+the diffractive differential cross-section (dsig/dt) data at the ISR and
+roughly accounts for the observed s-dependence of diffractive total
+cross-section up to Tevatron energies. However, an effective damping factor
+calculated for the CDF fitted function for dsig/dxidt at sqrt(s} = 1800 GeV and
+|t| = 0.05 GeV^2, suggests that, at fixed-xi, damping increases as s increases.
+  We conjecture that, in the regions where the triple-Regge formalism describes
+the data and there is no evidence of damping, factorization is valid and the
+Pomeron-flux-factor may be universal. With the assumption that the observed
+damping is due to multi-Pomeron exchange, our results imply that the recent UA8
+demonstration that the effective Pomeron trajectory flattens for |t| > 1 GeV$^2
+is evidence for the onset of the perturbative 2-gluon pomeron. Our damping
+results may also shed some light on the self-consistency of recent measurements
+of hard-diffractive jet production cross sections in the UA8, CDF and ZEUS
+experiments.",9804257v1
+2001-11-27,On the uniphase steady solutions of the nonlinear damped wave equation,"We study the steady uniphase and multiphase solutions of the discretized
+nonlinear damped wave equation.Conditions for the stability abd instability of
+the steady solutions are given;in the instability case the linear stable and
+unstable associated manifolds are described.",0111281v1
+2006-09-05,Damping estimates for oscillatory integral operators with finite type singularities,"We derive damping estimates and asymptotics of $L^p$ operator norms for
+oscillatory integral operators with finite type singularities. The methods are
+based on incorporating finite type conditions into $L^2$ almost orthogonality
+technique of Cotlar-Stein.",0609145v1
+2002-02-19,"On ""the authentic damping mechanism"" of the phonon damping model. II","This article continues a discussion raised in previous publications (LANL
+preprint server, nucl-th/0202006 and nucl-th/0202020). I try to convince my
+opponents that general arguments are not ""my case"" and may be applied to their
+model.",0202058v1
+1996-12-27,Coherent and trajectory-coherent states of a damped harmonic oscillator,"In this paper we construct the coherent and trajectory-coherent states of a
+damped harmonic oscillator. We investigate the properties of this states.",9612051v2
+2003-05-21,Probability representation of kinetic equation for open quantum system,"The tomographic probability distribution is used to decribe the kinetic
+equations for open quantum systems. Damped oscillator is studied. Purity
+parameter evolution for different damping regime is considered.",0305119v1
+2007-08-09,The resonant damping of fast magnetohydrodynamic oscillations in a system of two coronal slabs,"Observations of transversal coronal loop oscillations very often show the
+excitation and damping of oscillations in groups of coronal loops rather than
+in individual and isolated structures. We present results on the oscillatory
+properties (periods, damping rates, and spatial distribution of perturbations)
+for resonantly damped oscillations in a system of two inhomogeneous coronal
+slabs and compare them to the properties found in single slab loop models. A
+system of two identical coronal loops is modeled, in Cartesian geometry, as
+being composed by two density enhancements. The linear magnetohydrodynamic
+(MHD) wave equations for oblique propagation of waves are solved and the
+damping of the different solutions, due to the transversal inhomogeneity of the
+density profile, is computed. The physics of the obtained results is analyzed
+by an examination of the perturbed physical variables. We find that, due to the
+interaction between the loops, the normal modes of oscillation present in a
+single slab split into symmetric and antisymmetric oscillations when a system
+of two identical slabs is considered. The frequencies of these solutions may
+differ from the single slab results when the distance between the loops is of
+the order of a few slab widths. Oblique propagation of waves weakens this
+interaction, since solutions become more confined to the edges of the slabs.
+The damping is strong for surface-like oscillations, while sausage body-like
+solutions are unaffected. For some solutions, and small slab separations, the
+damping in a system of two loops differs substantially from the damping of a
+single loop.",0708.1251v1
+2009-12-08,Exact Invariant Solutions for Generalized Invicid Burgers' Equation with Damping,"In this work we study the Lie group analysis of a generalized invicid
+Burgers' equations with damping. Seven inequivalent classes of this generalized
+equation were classified and many exact and transformed solutions were obtained
+for each class.",0912.1631v1
+2011-07-28,Creating quantum discord through local generalized amplitude damping,"We show that two qubits initially in completely classical state can create
+quantum discord through a local generalized amplitude damping channel, but high
+temperature will impede the creating of quantum discord.",1107.5670v1
+2011-09-06,Damping of Alfven waves in solar partially ionized plasmas: effect of neutral helium in multi-fluid approach,"Chromospheric and prominence plasmas contain neutral atoms, which may change
+the plasma dynamics through collision with ions. Most of the atoms are neutral
+hydrogen, but a significant amount of neutral helium may also be present in the
+plasma with a particular temperature. Damping of MHD waves due to ion collision
+with neutral hydrogen is well studied, but the effects of neutral helium are
+largely unknown. We aim to study the effect of neutral helium in the damping of
+Alfven waves in solar partially ionized plasmas. We consider three-fluid
+magnetohydrodynamic (MHD) approximation, where one component is
+electron-proton-singly ionized helium and other two components are the neutral
+hydrogen and neutral helium atoms. We derive the dispersion relation of linear
+Alfven waves in isothermal and homogeneous plasma. Then we solve the dispersion
+relation and derive the damping rates of Alfven waves for different plasma
+parameters. The presence of neutral helium significantly enhances the damping
+of Alfven waves compared to the damping due to neutral hydrogen at certain
+values of plasma temperature (10000-40000 K) and ionization. Damping rates have
+a peak near the ion-neutral collision frequency, but decrease for the higher
+part of wave spectrum. Collision of ions with neutral helium atoms can be of
+importance for the damping of Alfven waves in chromospheric spicules and in
+prominence-corona transition regions.",1109.1154v1
+2012-03-08,Damping rates of solar-like oscillations across the HR diagram. Theoretical calculations confronted to CoRoT and Kepler observations,"Space-borne missions CoRoT and {\it Kepler} are providing a rich harvest of
+high-quality constraints on solar-like pulsators. Among the seismic parameters,
+mode damping rates remains poorly understood and thus barely used to infer
+physical properties of stars. Nevertheless, thanks to CoRoT and {\it Kepler}
+space-crafts it is now possible to measure damping rates for hundreds of
+main-sequence and thousands of red-giant stars with an unprecedented precision.
+  By using a non-adiabatic pulsation code including a time-dependent convection
+treatment, we compute damping rates for stellar models representative for
+solar-like pulsators from the main-sequence to the red-giant phase. This allows
+us to reproduce the observations of both CoRoT and {\it Kepler}, which
+validates our modeling of mode damping rates and thus the underlying physical
+mechanisms included in the modeling. Actually, by considering the perturbations
+of turbulent pressure and entropy (including perturbation of the dissipation
+rate of turbulent energy into heat) by the oscillation in our computation, we
+succeed in reproducing the observed relation between damping rates and
+effective temperature.
+  Moreover, we discuss the physical reasons for mode damping rates to scale
+with effective temperature, as observationally exhibited. Finally, this opens
+the way for the use of mode damping rates to probe turbulent convection in
+solar-like stars.",1203.1737v2
+2012-09-14,Semi-linear structural damped waves,"We study the global existence of small data solutions for Cauchy problem for
+the semi-linear structural damped wave equation with source term.",1209.3204v2
+2014-02-25,Asymptotic Profiles for wave equations with strong damping,"We consider the Cauchy problem in ${\bf R}^{n}$ for strongly damped wave
+equations. We derive asymptotic profiles of these solutions with weighted
+$L^{1,1}({\bf R}^{n})$ data by using a method introduced in [10].",1402.6073v1
+2014-04-17,Exponential stability of the wave equation with memory and time delay,"We study the asymptotic behaviour of the wave equation with viscoelastic
+damping in presence of a time-delayed damping. We prove exponential stability
+if the amplitude of the time delay term is small enough.",1404.4456v1
+2014-08-30,Marginalizing over the PageRank Damping Factor,"In this note, we show how to marginalize over the damping parameter of the
+PageRank equation so as to obtain a parameter-free version known as TotalRank.
+Our discussion is meant as a reference and intended to provide a guided tour
+towards an interesting result that has applications in information retrieval
+and classification.",1409.0104v1
+2014-10-29,Blowup for the nonlinear Schrödinger equation with an inhomogeneous damping term in the $L^2$ critical case,"We consider the nonlinear Schr\""odinger equation with $L^2$-critical exponent
+and an inhomogeneous damping term. By using the tools developed by Merle and
+Raphael, we prove the existence of blowup phenomena in the energy space
+$H^1(\mathbb{R})$.",1410.8011v1
+2014-11-28,Landau damping,"Landau damping is calculated using real variables, clarifying the physical
+mechanism.",1411.7793v1
+2014-12-16,Linear Collisionless Landau Damping in Hilbert Space,"The equivalence between the Laplace transform [Landau L., J. Phys. USSR, 10
+(1946), 25] and Hermite transform [Zocco and Schekochihin, Phys. Plasmas, 18,
+102309 (2011)] solutions of the linear collisionless Landau damping problem is
+proven.",1412.4913v1
+2015-07-08,Calculation of continuum damping of Alfvén eigenmodes in 2D and 3D cases,"In ideal MHD, shear Alfv\'{e}n eigenmodes may experience dissipationless
+damping due to resonant interaction with the shear Alfv\'{e}n continuum. This
+continuum damping can make a significant contribution to the overall
+growth/decay rate of shear Alfv\'{e}n eigenmodes, with consequent implications
+for fast ion transport. One method for calculating continuum damping is to
+solve the MHD eigenvalue problem over a suitable contour in the complex plane,
+thereby satisfying the causality condition. Such an approach can be implemented
+in three-dimensional ideal MHD codes which use the Galerkin method. Analytic
+functions can be fitted to numerical data for equilibrium quantities in order
+to determine the value of these quantities along the complex contour. This
+approach requires less resolution than the established technique of calculating
+damping as resistivity vanishes and is thus more computationally efficient. The
+complex contour method has been applied to the three-dimensional finite element
+ideal MHD code CKA . In this paper we discuss the application of the complex
+contour technique to calculate the continuum damping of global modes in tokamak
+as well as torsatron, W7X and H1-NF stellarator cases. To the authors'
+knowledge these stellarator calculations represent the first calculation of
+continuum damping for eigenmodes in fully three-dimensional equilibria. The
+continuum damping of global modes in W7X and H1-NF stellarator configurations
+investigated is found to depend sensitively on coupling to numerous poloidal
+and toroidal harmonics.",1507.02072v1
+2015-08-16,Jeans instability and hydrodynamic roots of Landau damping,"Landau damping of Langmuir waves is shown to have hydrodynamic roots, and, in
+principle, might have been predicted (along with Langmuir waves) several
+decades earlier, soon after Jeans (1902) paper appeared.",1508.03809v1
+2015-12-07,"Damped and zero-damped quasinormal modes of charged, nearly extremal black holes","Despite recent progress, the complete understanding of the perturbations of
+charged, rotating black holes as described by the Kerr-Newman metric remains an
+open and fundamental problem in relativity. In this study, we explore the
+existence of families of quasinormal modes of Kerr-Newman black holes whose
+decay rates limit to zero at extremality, called zero-damped modes in past
+studies. We review the nearly extremal and WKB approximation methods for
+spin-weighted scalar fields (governed by the Dudley-Finley equation) and give
+an accounting of the regimes where scalar zero-damped and damped modes exist.
+Using Leaver's continued fraction method, we verify that these approximations
+give accurate predictions for the frequencies in their regimes of validity. In
+the nonrotating limit, we argue that gravito-electromagnetic perturbations of
+nearly extremal Reissner-Nordstr\""{o}m black holes have zero-damped modes in
+addition to the well-known spectrum of damped modes. We provide an analytic
+formula for the frequencies of these modes, verify their existence using a
+numerical search, and demonstrate the accuracy of our formula. These results,
+along with recent numerical studies, point to the existence of a simple
+universal equation for the frequencies of zero-damped gravito-electromagnetic
+modes of Kerr-Newman black holes, whose precise form remains an open question.",1512.02247v2
+2016-09-24,Recovering the damping rates of cyclotron damped plasma waves from simulation data,"Plasma waves with frequencies close to the particular gyrofrequencies of the
+charged particles in the plasma lose energy due to cyclotron damping. We
+briefly discuss the gyro-resonance of low frequency plasma waves and ions
+particularly with regard to particle-in-cell (PiC) simulations. A setup is
+outlined which uses artificially excited waves in the damped regime of the wave
+mode's dispersion relation to track the damping of the wave's electromagnetic
+fields. Extracting the damping rate directly from the field data in real or
+Fourier space is an intricate and non-trivial task. We therefore present a
+simple method of obtaining the damping rate {\Gamma} from the simulation data.
+This method is described in detail, focusing on a step-by-step explanation of
+the course of actions. In a first application to a test simulation we find that
+the damping rates obtained from this simulation generally are in good agreement
+with theoretical predictions. We then compare the results of one-, two- and
+three-dimensional simulation setups and simulations with different physical
+parameter sets.",1609.07646v2
+2016-10-25,Quadratically damped oscillators with non-linear restoring force,"In this paper we qualitatively analyse quadratically damped oscillators with
+non-linear restoring force. In particular, we obtain Hamiltonian structure and
+analytical form of the energy functions.",1610.07821v1
+2016-11-24,Longitudinal Stability Study for the FACET-II e+ Damping Ring,"This is an initial study of the longitudinal, single-bunch stability in the
+proposed FACET-II e+ damping ring. It is preliminary because many vacuum
+chamber objects of the ring have not yet been designed.",1611.08042v1
+2017-08-25,On the entropy gain under the action of amplitude damping channel on qutrit,"After realising qutrit in the form of bipartite system we estimate from below
+the entropy gain under the action of the amplitude damping channel.",1708.07710v1
+2017-10-24,Demonstration of a switchable damping system to allow low-noise operation of high-Q low-mass suspension systems,"Low mass suspension systems with high-Q pendulum stages are used to enable
+quantum radiation pressure noise limited experiments. Utilising multiple
+pendulum stages with vertical blade springs and materials with high quality
+factors provides attenuation of seismic and thermal noise, however damping of
+these high-Q pendulum systems in multiple degrees of freedom is essential for
+practical implementation. Viscous damping such as eddy-current damping can be
+employed but introduces displacement noise from force noise due to thermal
+fluctuations in the damping system. In this paper we demonstrate a passive
+damping system with adjustable damping strength as a solution for this problem
+that can be used for low mass suspension systems without adding additional
+displacement noise in science mode. We show a reduction of the damping factor
+by a factor of 8 on a test suspension and provide a general optimisation for
+this system.",1710.08698v2
+2017-11-30,Asymptotic for a second order evolution equation with vanishing damping term and Tikhonov regularization,"We investigate the asymptotic behavior of solutions to a second order
+differential equation with vanishing damping term, convex potential and
+regularizing Tikhonov term.",1711.11241v1
+2018-10-04,Damping of slow surface sausage modes in photospheric waveguides,"There has been considerable interest in sausage modes in photospheric
+waveguides like pores and sunspots, and slow surface sausage modes (SSSMs) have
+been suggested to damp ufficiently rapidly to account for chromospheric
+heating. Working in the framework of linear resistive magnetohydrodynamics, we
+examine how efficient electric resistivity and resonant absorption in the cusp
+continuum can be for damping SSSMs in a photospheric waveguide with equilibrium
+parameters compatible with recent measurements of a photospheric pore. For
+SSSMs with the measured wavelength, we find that the damping rate due to the
+cusp resonance is substantially less strong than theoretically expected with
+the thin-boundary approximation. The damping-time-to-period ratio ($\tau/P$) we
+derive for standing modes, equivalent to the damping-length-to-wavelength ratio
+for propagating modes given the extremely weak dispersion, can reach only $\sim
+180$. However, the accepted values for electric resistivity ($\eta$) correspond
+to a regime where both the cusp resonance and resistivity play a role. The
+values for $\tau/P$ attained at the largest allowed $\eta$ may reach $\sim 30$.
+We conclude that electric resistivity can be considerably more efficient than
+the cusp resonance for damping SSSMs in the pore in question, and it needs to
+be incorporated into future studies on the damping of SSSMs in photospheric
+waveguides in general.",1810.02051v1
+2018-10-20,Landau Damping in a weakly collisional regime,"In this paper, we consider the nonlinear Vlasov-Poisson equations in a weakly
+collisional regime and study the linear Boltzmann collision operator. We prove
+that Landau damping still occurs in this case.",1810.10955v1
+2018-10-26,Energy regenerative damping in variable impedance actuators for long-term robotic deployment,"Energy efficiency is a crucial issue towards longterm deployment of compliant
+robots in the real world. In the context of variable impedance actuators
+(VIAs), one of the main focuses has been on improving energy efficiency through
+reduction of energy consumption. However, the harvesting of dissipated energy
+in such systems remains under-explored. This study proposes a novel variable
+damping module design enabling energy regeneration in VIAs by exploiting the
+regenerative braking effect of DC motors. The proposed damping module uses four
+switches to combine regenerative and dynamic braking, in a hybrid approach that
+enables energy regeneration without a reduction in the range of damping
+achievable. A physical implementation on a simple VIA mechanism is presented in
+which the regenerative properties of the proposed module are characterised and
+compared against theoretical predictions. To investigate the role of variable
+regenerative damping in terms of energy efficiency of longterm operation,
+experiments are reported in which the VIA equipped with the proposed damping
+module performs sequential reaching to a series of stochastic targets. The
+results indicate that the combination of variable stiffness and variable
+regenerative damping is preferable to achieve the optimal trade-off between
+task performance and energy efficiency. Use of the latter results in a 25%
+performance improvement on overall performance metrics (incorporating reaching
+accuracy, settling time, energy consumption and regeneration), over comparable
+schemes where either stiffness or damping are fixed.",1810.11246v3
+2018-12-26,A class large solution of the 2D MHD equations with velocity and magnetic damping,"In this paper, we construct a class global large solution to the
+two-dimensional MHD equations with damp terms in the nonhomogeneous Sobolev
+framework.",1812.10310v2
+2019-01-24,Generalization of Stokes-Einstein relation to coordinate dependent damping and diffusivity: An apparent conflict,"Brownian motion with coordinate dependent damping and diffusivity is
+ubiquitous. Understanding equilibrium of a Brownian particle with coordinate
+dependent diffusion and damping is a contentious area. In this paper, we
+present an alternative approach based on already established methods to this
+problem. We solve for the equilibrium distribution of the over-damped dynamics
+using Kramers-Moyal expansion. We compare this with the over-damped limit of
+the generalized Maxwell-Boltzmann distribution. We show that the equipartition
+of energy helps recover the Stokes-Einstein relation at constant diffusivity
+and damping of the homogeneous space. However, we also show that, there exists
+no homogeneous limit of coordinate dependent diffusivity and damping with
+respect to the applicability of Stokes-Einstein relation when it does not hold
+locally. In the other scenario where the Stokes-Einstein relation holds
+locally, one needs to impose a restriction on the local maximum velocity of the
+Brownian particle to make the modified Maxwell-Boltzmann distribution coincide
+with the modified Boltzmann distribution in the over-damped limit.",1901.08358v4
+2019-02-19,Linear inviscid damping near monotone shear flows,"We give an elementary proof of sharp decay rates and the linear inviscid
+damping near monotone shear flow in a periodic channel, first obtained in [14].
+We shall also obtain the precise asymptotics of the solutions, measured in the
+space $L^{\infty}$.",1902.06849v1
+2019-04-18,Damping of Propagating Kink Waves in the Solar Corona,"Alfv\'enic waves have gained renewed interest since the existence of
+ubiquitous propagating kink waves were discovered in the corona. {It has long
+been suggested that Alfv\'enic} waves play an important role in coronal heating
+and the acceleration of the solar wind. To this effect, it is imperative to
+understand the mechanisms that enable their energy to be transferred to the
+plasma. Mode conversion via resonant absorption is believed to be one of the
+main mechanisms for kink wave damping, and is considered to play a key role in
+the process of energy transfer. This study examines the damping of propagating
+kink waves in quiescent coronal loops using the Coronal Multi-channel
+Polarimeter (CoMP). A coherence-based method is used to track the Doppler
+velocity signal of the waves, enabling us to investigate the spatial evolution
+of velocity perturbations. The power ratio of outward to inward propagating
+waves is used to estimate the associated damping lengths and quality factors.
+To enable accurate estimates of these quantities, {we provide the first
+derivation of a likelihood function suitable for fitting models to the ratio of
+two power spectra obtained from discrete Fourier transforms. Maximum likelihood
+estimation is used to fit an exponential damping model to the observed
+variation in power ratio as a function of frequency.} We confirm earlier
+indications that propagating kink waves are undergoing frequency dependent
+damping. Additionally, we find that the rate of damping decreases, or
+equivalently the damping length increases, for longer coronal loops that reach
+higher in the corona.",1904.08834v1
+2019-05-19,Finite time blow up for wave equations with strong damping in an exterior domain,"We consider the initial boundary value problem in exterior domain for
+strongly damped wave equations with power type nonlinearity |u|^p. We will
+establish blow-up results under some conditions on the initial data and the
+exponent p.",1905.07782v1
+2019-12-15,A result for nonexistence of global solutions to semi-linear structural damped wave model,"Main goal of this note is to give a result for nonexistence of global
+solutions and determine the critical exponent as well to a semi-linear
+structurally damped wave equation.",1912.07066v1
+2020-10-13,The Impact of Damping in Second-Order Dynamical Systems with Applications to Power Grid Stability,"We consider a broad class of second-order dynamical systems and study the
+impact of damping as a system parameter on the stability, hyperbolicity, and
+bifurcation in such systems. We prove a monotonic effect of damping on the
+hyperbolicity of the equilibrium points of the corresponding first-order
+system. This provides a rigorous formulation and theoretical justification for
+the intuitive notion that damping increases stability. To establish this
+result, we prove a matrix perturbation result for complex symmetric matrices
+with positive semidefinite perturbations to their imaginary parts, which may be
+of independent interest. Furthermore, we establish necessary and sufficient
+conditions for the breakdown of hyperbolicity of the first-order system under
+damping variations in terms of observability of a pair of matrices relating
+damping, inertia, and Jacobian matrices, and propose sufficient conditions for
+Hopf bifurcation resulting from such hyperbolicity breakdown. The developed
+theory has significant applications in the stability of electric power systems,
+which are one of the most complex and important engineering systems. In
+particular, we characterize the impact of damping on the hyperbolicity of the
+swing equation model which is the fundamental dynamical model of power systems,
+and demonstrate Hopf bifurcations resulting from damping variations.",2010.06662v2
+2020-10-26,Linear Predictive Coding for Acute Stress Prediction from Computer Mouse Movements,"Prior work demonstrated the potential of using the Linear Predictive Coding
+(LPC) filter to approximate muscle stiffness and damping from computer mouse
+movements to predict acute stress levels of users. Theoretically, muscle
+stiffness and damping in the arm can be estimated using a mass-spring-damper
+(MSD) biomechanical model. However, the damping frequency (i.e., stiffness) and
+damping ratio values derived using LPC were not yet compared with those from a
+theoretical MSD model. This work demonstrates that the damping frequency and
+damping ratio from LPC are significantly correlated with those from an MSD
+model, thus confirming the validity of using LPC to infer muscle stiffness and
+damping. We also compare the stress level binary classification performance
+using the values from LPC and MSD with each other and with neural network-based
+baselines. We found comparable performance across all conditions demonstrating
+LPC and MSD model-based stress prediction efficacy, especially for longer mouse
+trajectories. Clinical relevance: This work demonstrates the validity of the
+LPC filter to approximate muscle stiffness and damping and predict acute stress
+from computer mouse movements.",2010.13836v3
+2020-11-01,Sharp dimension estimates of the attractor of the damped 2D Euler-Bardina equations,"We prove existence of the global attractor of the damped and driven 2D
+Euler--Bardina equations on the torus and give an explicit two-sided estimate
+of its dimension that is sharp as $\alpha\to0^+$.",2011.00607v1
+2021-03-30,Strong solution of 3D-NSE with exponential damping,"In this paper we prove the existence and uniqueness of strong solution of the
+incompressible Navier-Stokes equations with damping $\alpha
+(e^{\beta|u|^2}-1)u$.",2103.16707v1
+2021-09-27,Damping transition in an open generalized Aubry-André-Harper model,"We study the damping dynamics of the single-particle correlation for an open
+system under periodic and aperiodic order, which is dominated by the Lindblad
+master equation. In the absence of the aperiodic order, the Liouvillian
+superoperator exhibits the non-Hermitian skin effect, which leads to
+unidirectional damping dynamics, dubbed as ""chiral damping"". Due to the
+non-Hermitian skin effect, the damping dynamics is boundary sensitive: The
+long-time damping of such open systems is algebraic under periodic boundary
+conditions but exponential under open boundary conditions. We reveal the phase
+transition with the inclusion of the hopping amplitude modulation. By using the
+spectral topology and a finite-size scaling analysis in the commensurate case,
+we show there exists a phase transition of the skin effect with non-Bloch
+anti-parity-time symmetry breaking. For the incommensurate case, we find richer
+phases with the coexistence of the non-Hermitian skin effect and the Anderson
+localization, which are separated by a generalized mobility edge. We reveal the
+transition of the damping dynamics as a consequence of the phase transition.
+Furthermore, we propose a possible scheme with ultracold atoms in a dissipative
+momentum lattice to realize and detect the damping dynamics.",2109.12958v2
+2022-01-20,Long Time Decay of Leray Solution of 3D-NSE With Exponential Damping,"We study the uniqueness, the continuity in $L^2$ and the large time decay for
+the Leray solutions of the $3D$ incompressible Navier-Stokes equations with
+nonlinear exponential damping term $a (e^{b |u|^{\bf 4}}-1)u$, ($a,b>0$).",2201.08292v1
+2023-09-04,Joint Oscillation Damping and Inertia Provision Service for Converter-Interfaced Generation,"As renewable generation becomes more prevalent, traditional power systems
+dominated by synchronous generators are transitioning to systems dominated by
+converter-interfaced generation. These devices, with their weaker damping
+capabilities and lower inertia, compromise the system's ability to withstand
+disturbances, pose a threat to system stability, and lead to oscillations and
+poor frequency response performance. While some new converter-interfaced
+generations are capable of providing superior damping and fast frequency
+control, there is a lack of effective measures to incentivize manufacturers to
+adopt them. To address this gap, this paper defines the joint oscillation
+damping and inertia provision services at the system level, seeking to
+encourage converter-interfaced generation to provide enhanced damping and fast
+frequency response capabilities. Our approach is anchored in a novel convex
+parametric formulation that combines oscillation mode and frequency stability
+constraints. These constraints ensure a sufficient damping ratio for all
+oscillation modes and maintain transient frequency trajectories within
+acceptable limits. They are designed to integrate smoothly into various
+operational and planning optimization frameworks. Using this formulation, we
+introduce a joint service for oscillation damping and inertia provision based
+on a cost-minimization problem. This facilitates the optimal allocation of
+damping and virtual inertia to converters, achieving both small-signal
+stability and frequency stability. Furthermore, we investigate the economic
+effects of introducing this service into a new ancillary service market,
+assessing its impact on system operations and cost-efficiency. Numerical tests
+highlight the service's efficacy in ensuring both small-signal stability and
+frequency stability, and offer insights into potential economic benefits.",2309.01321v1
+2024-01-30,The Velocity-Space Signature of Transit-Time Damping,"Transit-time damping (TTD) is a process in which the magnetic mirror force --
+induced by the parallel gradient of magnetic field strength -- interacts with
+resonant plasma particles, leading to the collisionless damping of
+electromagnetic waves and the resulting energization of those particles through
+the perpendicular component of the electric field, $E_\perp$. In this study, we
+utilize the recently developed field-particle correlation technique to analyze
+gyrokinetic simulation data. This method enables the identification of the
+velocity-space structure of the TTD energy transfer rate between waves and
+particles during the damping of plasma turbulence. Our analysis reveals a
+unique bipolar pattern of energy transfer in velocity space characteristic of
+TTD. By identifying this pattern, we provide clear evidence of TTD's
+significant role in the damping of strong plasma turbulence. Additionally, we
+compare the TTD signature with that of Landau damping (LD). Although they both
+produce a bipolar pattern of phase-space energy density loss and gain about the
+parallel resonant velocity of the \Alfvenic waves, they are mediated by
+different forces and exhibit different behaviors as $v_\perp \to 0$. We also
+explore how the dominant damping mechanism varies with ion plasma beta
+$\beta_i$, showing that TTD dominates over LD for $\beta_i > 1$. This work
+deepens our understanding of the role of TTD in the damping of weakly
+collisional plasma turbulence and paves the way to seek the signature of TTD
+using in situ spacecraft observations of turbulence in space plasmas.",2401.16697v1
+2024-03-04,How long will the quasar UV/optical flickering be damped?,"The UV/optical light curves of Active Galactic Nuclei (AGNs) are commonly
+described by the Damped Random Walk (DRW) model. However, the physical
+interpretation of the damping timescale, a key parameter in the DRW model,
+remains unclear. Particularly, recent observations indicate a weak dependence
+of the damping timescale upon both wavelength and accretion rate, clearly being
+inconsistent with the accretion-disk theory. In this study, we investigate the
+damping timescale in the framework of the Corona Heated Accretion disk
+Reprocessing (CHAR) model, a physical model that describes AGN variability. We
+find that while the CHAR model can reproduce the observed power spectral
+densities of the 20-year light curves for 190 sources from \cite{Stone2022},
+the observed damping timescale, as well as its weak dependence on wavelength,
+can also be well recovered through fitting the mock light curves with DRW. We
+further demonstrate that such weak dependence is artificial due to the effect
+of inadequate durations of light curves, which leads to best-fitting damping
+timescales lower than the intrinsic ones. After eliminating this effect, the
+CHAR model indeed yields a strong dependence of the intrinsic damping timescale
+on the bolometric luminosity and rest-frame wavelength. Our results highlight
+the demand for sufficiently long light curves in AGN variability studies and
+important applications of the CHAR model in such studies.",2403.01691v1
+2005-04-18,Chemical Abundances in SFG and DLA,"We investigate the chemical abundances of local star-forming galaxies which
+cause Damped Lyman Alpha lines. A metallicity versus redshift diagram is
+constructed, on which the chemical abundances of low-redshift star-forming
+galaxy populations are compared with those of high-redshift Damped Lyman Alpha
+systems. We disucss two types of experiments on individual star-forming
+galaxies. In the first, the Damped Lyman Alpha line is created against an
+internal ultraviolet light source generated by a star-forming cluster or a
+supernova explosion. In the second, the Damped Lyman Alpha line is seen against
+a background Quasar. The metallicities measured from ionized gas in the
+star-forming regions, and neutral gas in the Damped Lyman Alpha systems, are
+compared with one another on a case-by-case basis. We highlight the occurrence
+of the star-forming galaxy/Quasar pair SBS 1543+593/HS 1543+5921, where the
+emission- and absorption-line derived abundances give the same result. We argue
+that we therefore can in principle, interpret Damped Lyman Alpha system
+metallicities as an extension of star-forming galaxy metallicities to higher
+redshifts, supporting that gas-rich galaxies had lower chemical abundances when
+the were younger.",0504389v2
+1995-09-06,Fermi Liquid Damping and NMR Relaxation in Superconductors,"Electron collisions for a two dimensional Fermi liquid (FL) are shown to give
+a quasiparticle damping with interesting frequency and temperature variations
+in the BCS superconducting state. The spin susceptibility which determines the
+structure of the damping is analyzed in the normal state for a Hubbard model
+with a constant on--site Coulomb repulsion. This is then generalized to the
+superconducting state by including coherence factors and self energy and vertex
+corrections. Calculations of the NMR relaxation rate reveal that the FL damping
+structure can reduce the Hebel--Slichter peak, in agreement with data on the
+organic superconductor (MDT-TTF)$_2$AuI$_2$. However, the strongly suppressed
+FL damping in the superconducting state does not eliminate the Hebel-Slichter
+peak, and thus suggests that other mechanisms are needed to explain the NMR
+data on (TMTSF)$_2$ClO$_4$, the BEDT organic compounds, and cuprate
+superconductors. Predictions of the temperature variation of the damping and
+the spin response are given over a wide frequency range as a guide to
+experimental probes of the symmetry of the superconducting pairs.",9509028v1
+1997-05-08,Topological asymmetry in the damping-pairing contribution of electron-boson scattering,"We make a harmonic analysis of the pairing and damping contribution of a
+finite $k$ range isotropic electron-phonon (or other boson) scattering in an
+anisotropic two-dimensional electronic system. We show that the pairing
+contribution of the anisotropic part of the electronic system can be much
+larger than its damping contribution enhancing significantly T_c. The higher is
+the order of the harmonic of the electronic anisotropy, smaller is its damping
+contribution and higher can be the asymmetry in its damping-pairing
+contribution. This could explain the puzzle of a much broader quasiparticle
+peak in the n-doped than in the p-doped cuprates, their smaller T_c's being
+also attributed to larger damping effects.",9705071v1
+2000-03-29,Damping of condensate collective modes due to equilibration with the non-condensate,"We consider the damping of condensate collective modes at finite temperatures
+arising from lack of equilibrium between the condensate and the non-condensate
+atoms, an effect that is ignored in the usual discussion of the collisionless
+region. As a first approximation, we ignore the dynamics of the thermal cloud.
+Our calculations should be applicable to collective modes of the condensate
+which are oscillating out-of-phase with the thermal cloud. We obtain a
+generalized Stringari equation of motion for the condensate at finite
+temperatures, which includes a damping term associated with the fact that the
+condensate is not in diffusive equilibrium with the static thermal cloud. This
+inter-component collisional damping of the condensate modes is comparable in
+magnitude to the Landau damping considered in the recent literature.",0003481v5
+2006-06-27,Theoretical limit of the minimal magnetization switching field and the optimal field pulse for Stoner particles,"The theoretical limit of the minimal magnetization switching field and the
+optimal field pulse design for uniaxial Stoner particles are investigated. Two
+results are obtained. One is the existence of a theoretical limit of the
+smallest magnetic field out of all possible designs. It is shown that the limit
+is proportional to the damping constant in the weak damping regime and
+approaches the Stoner-Wohlfarth (SW) limit at large damping. For a realistic
+damping constant, this limit is more than ten times smaller than that of
+so-called precessional magnetization reversal under a non-collinear static
+field. The other is on the optimal field pulse design: If the magnitude of a
+magnetic field does not change, but its direction can vary during a reversal
+process, there is an optimal design that gives the shortest switching time. The
+switching time depends on the field magnitude, damping constant, and magnetic
+anisotropy. However, the optimal pulse shape depends only on the damping
+constant.",0606681v1
+2001-02-09,Magnetic effects on the viscous boundary layer damping of the r-modes in neutron stars,"This paper explores the effects that magnetic fields have on the viscous
+boundary layers (VBLs) that can form in neutron stars at the crust-core
+interface, and it investigates the VBL damping of the gravitational-radiation
+driven r-mode instability. Approximate solutions to the magnetohydrodynamic
+equations valid in the VBL are found for ordinary-fluid neutron stars. It is
+shown that magnetic fields above 10^9 Gauss significantly change the structure
+of the VBL, and that magnetic fields decrease the VBL damping time.
+Furthermore, VBL damping completely suppresses the r-mode instability for B >=
+10^{12} Gauss. Thus, magnetic fields will profoundly affect the VBL damping of
+the r-mode instability in hot young pulsars (that are cool enough to have
+formed a solid crust). One can speculate that magnetic fields can affect the
+VBL damping of this instability in LMXBs and other cold old pulsars (if they
+have sufficiently large internal fields).",0102042v1
+2002-07-26,Landau damping of partially incoherent Langmuir waves,"It is shown that partial incoherence, in the form of stochastic phase noise,
+of a Langmuir wave in an unmagnetized plasma gives rise to a Landau-type
+damping. Starting from the Zakharov equations, which describe the nonlinear
+interaction between Langmuir and ion-acoustic waves, a kinetic equation is
+derived for the plasmons by introducing the Wigner-Moyal transform of the
+complex Langmuir wave field. This equation is then used to analyze the
+stability properties of small perturbations on a stationary solution consisting
+of a constant amplitude wave with stochastic phase noise. The concomitant
+dispersion relation exhibits the phenomenon of Landau-like damping. However,
+this damping differs from the classical Landau damping in which a Langmuir
+wave, interacting with the plasma electrons, loses energy. In the present
+process, the damping is non-dissipative and is caused by the resonant
+interaction between an instantaneously-produced disturbance, due to the
+parametric interactions, and a partially incoherent Langmuir wave, which can be
+considered as a quasi-particle composed of an ensemble of partially incoherent
+plasmons.",0207050v1
+2007-12-18,"Spectroscopy of electronic defect states in Cu(In, Ga)(S, Se)$_2$-based heterojunctions and Schottky diodes under damp-heat exposure","The changes of defect characteristics induced by accelerated lifetime tests
+on the heterostructure n-ZnO/i-ZnO/CdS/Cu(In, Ga)(S, Se)$_2$/Mo relevant for
+photovoltaic energy conversion are investigated. We subject heterojunction and
+Schottky devices to extended damp heat exposure at 85$^{\circ}$C ambient
+temperature and 85% relative humidity for various time periods. In order to
+understand the origin of the pronounced changes of the devices, we apply
+current--voltage and capacitance--voltage measurements, admittance
+spectroscopy, and deep-level transient spectroscopy. The fill factor and
+open-circuit voltage of test devices are reduced after prolonged damp heat
+treatment, leading to a reduced energy conversion efficiency. We observe the
+presence of defect states in the vicinity of the CdS/chalcopyrite interface.
+Their activation energy increases due to damp heat exposure, indicating a
+reduced band bending at the Cu(In, Ga)(S, Se)$_2$ surface. The Fermi-level
+pinning at the buffer/chalcopyrite interface, maintaining a high band bending
+in as-grown cells, is lifted due to the damp-heat exposure. We also observe
+changes in the bulk defect spectra due to the damp-heat treatment.",0712.2982v1
+2009-01-26,Dispersion of Waves in Relativistic Plasmas with Isotropic Particle Distributions,"The dispersion laws of Langmuir and transverse waves are calculated in the
+relativistic non-magnetized formalism for several isotropic particle
+distributions: thermal, power-law, relativistic Lorentzian $\kappa,$ and hybrid
+$\beta$. For Langmuir waves the parameters of superluminal undamped, subluminal
+damped principal and higher modes are determined for a range of distribution
+parameters. The undamped and principal damped modes are found to match
+smoothly. Principal damped and second damped modes are found not to match
+smoothly. The presence of maximum wavenumber is discovered above that no
+longitudinal modes formally exist. The higher damped modes are discovered to be
+qualitatively different for thermal and certain non-thermal distributions.
+Consistently with the known results, the Landau damping is calculated to be
+stronger for non-thermal power-law-like distributions. The dispersion law is
+obtained for the single undamped transverse mode. The analytic results for the
+simplest distributions are provided.",0901.4050v1
+2009-03-28,Torsional waves propagation in an initially stressed dissipative cylinder,"The present paper has been framed to show the effect of damping on the
+propagation of torsional waves in an initially stressed, dissipative,
+incompressible cylinder of infinite length. A governing equation has been
+formulated on Biot's incremental deformation theory. The velocities of
+torsional waves are obtained as complex ones, in which real part gives the
+phase velocity of propagation and corresponding imaginary part gives the
+damping. The study reveals that the damping of the medium has strong effect in
+the propagation of torsional wave. Since every medium has damping so it is more
+realistic to use the damped wave equation instead of the undamped wave
+equation. The study also shows that the velocity of propagation of such waves
+depend on the presence of initial stress. The influences of damping and initial
+stresses are shown separately.",0903.4896v1
+2009-04-29,Atomistic theory for the damping of vibrational modes in mono-atomic gold chains,"We develop a computational method for evaluating the damping of vibrational
+modes in mono-atomic metallic chains suspended between bulk crystals under
+external strain. The damping is due to the coupling between the chain and
+contact modes and the phonons in the bulk substrates. The geometry of the atoms
+forming the contact is taken into account. The dynamical matrix is computed
+with density functional theory in the atomic chain and the contacts using
+finite atomic displacements, while an empirical method is employed for the bulk
+substrate. As a specific example, we present results for the experimentally
+realized case of gold chains in two different crystallographic directions. The
+range of the computed damping rates confirm the estimates obtained by fits to
+experimental data [Frederiksen et al., Phys. Rev. B, 75, 205413(R)(2007)]. Our
+method indicates that an order-of-magnitude variation in the damping is
+possible even for relatively small changes in the strain. Such detailed insight
+is necessary for a quantitative analysis of damping in metallic atomic chains,
+and in explaining the rich phenomenology seen in the experiments.",0904.4627v2
+2009-12-20,A Kinetic Alfven wave cascade subject to collisionless damping cannot reach electron scales in the solar wind at 1 AU,"(Abridged) Turbulence in the solar wind is believed to generate an energy
+cascade that is supported primarily by Alfv\'en waves or Alfv\'enic
+fluctuations at MHD scales and by kinetic Alfv\'en waves (KAWs) at kinetic
+scales $k_\perp \rho_i\gtrsim 1$. Linear Landau damping of KAWs increases with
+increasing wavenumber and at some point the damping becomes so strong that the
+energy cascade is completely dissipated. A model of the energy cascade process
+that includes the effects of linear collisionless damping of KAWs and the
+associated compounding of this damping throughout the cascade process is used
+to determine the wavenumber where the energy cascade terminates. It is found
+that this wavenumber occurs approximately when $|\gamma/\omega|\simeq 0.25$,
+where $\omega(k)$ and $\gamma(k)$ are, respectively, the real frequency and
+damping rate of KAWs and the ratio $\gamma/\omega$ is evaluated in the limit as
+the propagation angle approaches 90 degrees relative to the direction of the
+mean magnetic field.",0912.4026v2
+2010-07-27,Alfvèn wave phase-mixing and damping in the ion cyclotron range of frequencies,"Aims. To determine the effect of the Hall term in the generalised Ohm's law
+on the damping and phase mixing of Alfven waves in the ion cyclotron range of
+frequencies in uniform and non-uniform equilibrium plasmas. Methods. Wave
+damping in a uniform plasma is treated analytically, whilst a Lagrangian remap
+code (Lare2d) is used to study Hall effects on damping and phase mixing in the
+presence of an equilibrium density gradient. Results. The magnetic energy
+associated with an initially Gaussian field perturbation in a uniform resistive
+plasma is shown to decay algebraically at a rate that is unaffected by the Hall
+term to leading order in k^2di^2 where k is wavenumber and di is ion skin
+depth. A similar algebraic decay law applies to whistler perturbations in the
+limit k^2di^2>>1. In a non-uniform plasma it is found that the
+spatially-integrated damping rate due to phase mixing is lower in Hall MHD than
+it is in MHD, but the reduction in the damping rate, which can be attributed to
+the effects of wave dispersion, tends to zero in both the weak and strong phase
+mixing limits.",1007.4752v2
+2011-02-24,Environment-assisted quantum Minority games,"The effect of entanglement and correlated noise in a four-player quantum
+Minority game is investigated. Different time correlated quantum memory
+channels are considered to analyze the Nash equilibrium payoff of the 1st
+player. It is seen that the Nash equilibrium payoff is substantially enhanced
+due to the presence of correlated noise. The behaviour of damping channels
+(amplitude damping and phase damping) is approximately similar. However,
+bit-phase flip channel heavily influences the minority game as compared to
+other channels in the presence of correlated noise. On the other hand, phase
+flip channel has a symmetrical behaviour around 50% noise threshold. The
+significant reduction in payoffs due to decoherence is well compensated due to
+the presence of correlated noise. However, the Nash equilibrium of the game
+does not change in the presence of noise. It is seen that in case of
+generalized amplitude damping channel, entanglement plays a significant role at
+lower level of decoherence. The channel has less dominant effects on the payoff
+at higher values of decoherence. Furthermore, amplitude damping and generalized
+amplitude damping channels have almost comparable effects at lower level of
+decoherence $(p<0.5)$. Therefore, the game deserves careful study during its
+implementation due to prominent role of noise for different channels.",1102.5056v2
+2011-03-17,Viscous damping of r-modes: Large amplitude saturation,"We analyze the viscous damping of r-mode oscillations of compact stars,
+taking into account non-linear viscous effects in the large-amplitude regime.
+The qualitatively different cases of hadronic stars, strange quark stars, and
+hybrid stars are studied. We calculate the viscous damping times of r-modes,
+obtaining numerical results and also general approximate analytic expressions
+that explicitly exhibit the dependence on the parameters that are relevant for
+a future spindown evolution calculation. The strongly enhanced damping of large
+amplitude oscillations leads to damping times that are considerably lower than
+those obtained when the amplitude dependence of the viscosity is neglected.
+Consequently, large-amplitude viscous damping competes with the gravitational
+instability at all physical frequencies and could stop the r-mode growth in
+case this is not done before by non-linear hydrodynamic mechanisms.",1103.3521v2
+2011-05-01,"Viscous damping of nanobeam resonators: humidity, thermal noise and the paddling effect","The nanobeam resonator is the key mechanical component in the
+nano-electromechanical system. In addition to its high frequency originating
+from its low dimension, the performance is significantly influenced by the
+circumstances, especially at nanoscale where a large surface area of the
+material is exposed. Molecular dynamics simulations and theoretical analysis
+are used for a quantitative prediction on the damping behavior, such as the
+critical damping condition and lifetime, of nanobeam resonators that directly
+maps the fluid-structure properties and interaction information into dynamical
+behaviors. We show here how the humidity defines the critical damping condition
+through viscous forces, marking the transition from under-damping to
+over-damping regime at elevated humidity. Novel phenomena such as the thermal
+fluctuation and paddling effects are also discussed.",1105.0139v1
+2011-06-07,Damping by branching: a bioinspiration from trees,"Man-made slender structures are known to be sensitive to high levels of
+vibration, due to their flexibility, which often cause irreversible damage. In
+nature, trees repeatedly endure large amplitudes of motion, mostly caused by
+strong climatic events, yet with minor or no damage in most cases. A new
+damping mechanism inspired by the architecture of trees is here identified and
+characterized in the simplest tree-like structure, a Y-shape branched
+structure. Through analytical and numerical analyses of a simple
+two-degree-of-freedom model, branching is shown to be the key ingredient in
+this protective mechanism that we call damping-by-branching. It originates in
+the geometrical nonlinearities so that it is specifically efficient to damp out
+large amplitudes of motion. A more realistic model, using flexible beam
+approximation, shows that the mechanism is robust. Finally, two bioinspired
+architectures are analyzed, showing significant levels of damping achieved via
+branching with typically 30% of the energy being dissipated in one oscillation.
+This concept of damping-by-branching is of simple practical use in the design
+of slender flexible structures.",1106.1283v1
+2011-11-29,Dispersion and damping of potential surface waves in a degenerate plasma,"Potential (electrostatic) surface waves in plasma half-space with degenerate
+electrons are studied using the quasi-classical mean-field kinetic model. The
+wave spectrum and the collisionless damping rate are obtained numerically for a
+wide range of wavelengths. In the limit of long wavelengths, the wave frequency
+$\omega$ approaches the cold-plasma limit $\omega=\omega_p/\sqrt{2}$ with
+$\omega_p$ being the plasma frequency, while at short wavelengths, the wave
+spectrum asymptotically approaches the spectrum of zero-sound mode propagating
+along the boundary. It is shown that the surface waves in this system remain
+weakly damped at all wavelengths (in contrast to strongly damped surface waves
+in Maxwellian electron plasmas), and the damping rate nonmonotonically depends
+on the wavelength, with the maximum (yet small) damping occuring for surface
+waves with wavelength of $\approx5\pi\lambda_{F}$, where $\lambda_{F}$ is the
+Thomas-Fermi length.",1111.6723v1
+2012-01-29,Smooth attractors of finite dimension for von Karman evolutions with nonlinear frictional damping localized in a boundary layer,"In this paper dynamic von Karman equations with localized interior damping
+supported in a boundary collar are considered. Hadamard well-posedness for von
+Karman plates with various types of nonlinear damping are well-known, and the
+long-time behavior of nonlinear plates has been a topic of recent interest.
+Since the von Karman plate system is of ""hyperbolic type"" with critical
+nonlinearity (noncompact with respect to the phase space), this latter topic is
+particularly challenging in the case of geometrically constrained and nonlinear
+damping. In this paper we first show the existence of a compact global
+attractor for finite-energy solutions, and we then prove that the attractor is
+both smooth and finite dimensional. Thus, the hyperbolic-like flow is
+stabilized asymptotically to a smooth and finite dimensional set.
+  Key terms: dynamical systems, long-time behavior, global attractors,
+nonlinear plates, nonlinear damping, localized damping",1201.6072v1
+2012-06-15,Landau Damping in a Turbulent Setting,"To address the problem of Landau damping in kinetic turbulence, the forcing
+of the linearized Vlasov equation by a stationary random source is considered.
+It is found that the time-asymptotic density response is dominated by resonant
+particle interactions that are synchronized with the source. The energy
+consumption of this response is calculated, implying an effective damping rate,
+which is the main result of this paper. Evaluating several cases, it is found
+that the effective damping rate can differ from the Landau damping rate in
+magnitude and also, remarkably, in sign. A limit is demonstrated in which the
+density and current become phase-locked, which causes the effective damping to
+be negligible; this potentially resolves an energy paradox that arises in the
+application of critical balance to a kinetic turbulence cascade.",1206.3415v4
+2013-10-29,Influence of sample geometry on inductive damping measurement methods,"We study the precession frequency and effective damping of patterned
+permalloy thin films of different geometry using integrated inductive test
+structures. The test structures consist of coplanar wave guides fabricated onto
+patterned permalloy stripes of different geometry. The width, length and
+position of the permalloy stripe with respect to the center conductor of the
+wave guide are varied. The precession frequency and effective damping of the
+different devices is derived by inductive measurements in time and frequency
+domain in in-plane magnetic fields. While the precession frequencies do not
+reveal a significant dependence on the sample geometry we find a decrease of
+the measured damping with increasing width of the permalloy centered underneath
+the center conductor of the coplanar wave guide. We attribute this effect to an
+additional damping contribution due to inhomogeneous line broadening at the
+edges of the permalloy stripes which does not contribute to the inductive
+signal provided the permalloy stripe is wider than the center conductor.
+Consequences for inductive determination of the effective damping using such
+integrated reference samples are discussed.",1310.7817v1
+2014-04-02,Determination of the cross-field density structuring in coronal waveguides using the damping of transverse waves,"Time and spatial damping of transverse magnetohydrodynamic (MHD) kink
+oscillations is a source of information on the cross-field variation of the
+plasma density in coronal waveguides. We show that a probabilistic approach to
+the problem of determining the density structuring from the observed damping of
+transverse oscillations enables us to obtain information on the two parameters
+that characterise the cross-field density profile. The inference is performed
+by computing the marginal posterior distributions for density contrast and
+transverse inhomo- geneity length-scale using Bayesian analysis and damping
+ratios for transverse oscillations under the assumption that damping is
+produced by resonant absorption. The obtained distributions show that, for
+damping times of a few oscillatory periods, low density contrasts and short
+inho- mogeneity length scales are more plausible in explaining observations.
+This means that valuable information on the cross-field density profile can be
+obtained even if the inversion problem, with two unknowns and one observable,
+is a mathematically ill-posed problem.",1404.0584v1
+2014-04-14,Distributed Approximate Message Passing for Compressed Sensing,"In this paper, an efficient distributed approach for implementing the
+approximate message passing (AMP) algorithm, named distributed AMP (DAMP), is
+developed for compressed sensing (CS) recovery in sensor networks with the
+sparsity K unknown. In the proposed DAMP, distributed sensors do not have to
+use or know the entire global sensing matrix, and the burden of computation and
+storage for each sensor is reduced. To reduce communications among the sensors,
+a new data query algorithm, called global computation for AMP (GCAMP), is
+proposed. The proposed GCAMP based DAMP approach has exactly the same recovery
+solution as the centralized AMP algorithm, which is proved theoretically in the
+paper. The performance of the DAMP approach is evaluated in terms of the
+communication cost saved by using GCAMP. For comparison purpose, thresholding
+algorithm (TA), a well known distributed Top-K algorithm, is modified so that
+it also leads to the same recovery solution as the centralized AMP. Numerical
+results demonstrate that the GCAMP based DAMP outperforms the Modified TA based
+DAMP, and reduces the communication cost significantly.",1404.3766v2
+2014-12-17,The most metal-rich damped Lyman alpha systems at z>1.5 I: The Data,"We present HIRES observations for 30 damped Lyman alpha systems, selected on
+the basis of their large metal column densities from previous, lower resolution
+data. The measured metal column densities for Fe, Zn, S, Si, Cr, Mn, and Ni are
+provided for these 30 systems. Combined with previously observed large metal
+column density damped Lyman alpha systems, we present a sample of 44 damped
+Lyman alpha systems observed with high resolution spectrographs (R~30000).
+These damped Lyman alpha systems probe the most chemically evolved systems at
+redshifts greater than 1.5. We discuss the context of our sample with the
+general damped Lyman alpha population, demonstrating that we are probing the
+top 10% of metal column densities with our sample. In a companion paper, we
+will present an analysis of the sample's elemental abundances in the context of
+galactic chemical enrichment.",1412.5491v1
+2015-03-26,Transient nutations decay in diluted paramagnetic solids: a radiation damping mechanism,"Here, a theory of the intensity and concentration dependent damping of
+nutation signals observed by Boscaino et al. (Phys. Rev B 48, 7077 (1993);
+Phys. Rev. A 59, 4087 (1999)) and by others in various two-level spin systems
+is proposed. It is shown that in diluted paramagnetic solids contribution of
+dipole-dipole interaction to the nutation decay is negligibly small. We
+elaborated a cavity loss (radiation damping) mechanism that explains the
+intensity- and concentration dependence of the damping. It is shown that
+instead of ordinary Bloch's transverse T2 and longitudinal T1 damping
+parameters the decay of transverse and longitudinal spin components in nutation
+process are described by one and the same intensity-, concentration-,
+frequency- and time dependent damping parameter.",1503.07641v2
+2015-08-17,Increased magnetic damping of a single domain wall and adjacent magnetic domains detected by spin torque diode in a nanostripe,"We use spin-torque resonance to probe simultaneously and separately the
+dynamics of a magnetic domain wall and of magnetic domains in a nanostripe
+magnetic tunnel junction. Thanks to the large associated resistance variations
+we are able to analyze quantitatively the resonant properties of these single
+nanoscale magnetic objects. In particular, we find that the magnetic damping of
+both domains and domain walls is doubled compared to the damping value of their
+host magnetic layer. We estimate the contributions to damping arising from
+dipolar couplings between the different layers in the junction and from the
+intralayer spin pumping effect. We find that they cannot explain the large
+damping enhancement that we observe. We conclude that the measured increased
+damping is intrinsic to large amplitudes excitations of spatially localized
+modes or solitons such as vibrating or propagating domain walls",1508.04043v1
+2016-04-27,Influence of nonlocal damping on the field-driven domain wall motion,"We derive the complete expression of nonlocal damping in noncollinear
+magnetization due to the nonuniform spin current pumped by precessional
+magnetization and incorporate it into a generalized Thiele equation to study
+its effects on the dynamics of the transverse and vortex domain walls (DWs) in
+ferromagnetic nanowires. We demonstrate that the transverse component of
+nonlocal damping slows down the field-driven DW propagation and increases the
+Walker breakdown field whereas it is neglected in many previous works in
+literature. The experimentally measured DW mobility variation with the damping
+tuned by doping with heavy rare-earth elements that had discrepancy from
+micromagnetic simulation are now well understood with the nonlocal damping. Our
+results suggest that the nonlocal damping should be properly included as a
+prerequisite for quantitative studies of current-induced torques in
+noncollinear magnetization.",1604.07971v2
+2016-04-27,Damping of the Collective Amplitude Mode in Superconductors with Strong Electron-Phonon Coupling,"We study the effect of strong electron-phonon interactions on the damping of
+the Higgs amplitude mode in superconductors by means of non-equilibrium
+dynamical mean-field simulations of the Holstein model. In contrast to the BCS
+dynamics, we find that the damping of the Higgs mode strongly depends on the
+temperature, becoming faster as the systen approaches the transition
+temperature. The damping at low temperatures is well described by a power-law,
+while near the transition temperature the damping shows exponential-like
+behavior. We explain this crossover by a temperature-dependent quasiparticle
+lifetime caused by the strong electron- phonon coupling, which smears the
+superconducting gap edge and makes the relaxation of the Higgs mode into
+quasiparticles more efficient at elevated temperatures. We also reveal that the
+phonon dynamics can soften the Higgs mode, which results in a slower damping.",1604.08073v2
+2016-12-16,Dynamics of cohering and decohering power under Markovian channels,"In this paper, we investigate the cohering and decohering power for the
+one-qubit Markovian channels with respect to coherence in terms of the
+$l_{1}$-norm, the R$\acute{e}$nyi $\alpha$-relative entropy and the Tsallis
+$\alpha$-relative entropy. In the case of $\alpha=2$, the cohering and
+decohering power of the amplitude damping channel, the phase damping channel,
+the depolarizing channel, and the flip channels under the three measures of
+coherence are calculated analytically. The decohering power on the $x, y, z$
+basis referring to the amplitude damping channel, the phase damping channel,
+the flip channel for every measure we investigated is equal. This property also
+happens in the cohering power of the phase damping channel, the depolarizing
+channel, and the flip channels. However, the decohering power of the
+depolarizing channel is independent to the reference basis, and the cohering
+power of the amplitude damping channel on the $x, y$ basis is different to that
+on the $z$ basis.",1612.05355v1
+2017-01-19,Decoherence effects on multiplayer cooperative quantum games,"We study the behavior of cooperative multiplayer quantum games [35,36] in the
+presence of decoherence using different quantum channels such as amplitude
+damping, depolarizing and phase damping. It is seen that the outcomes of the
+games for the two damping channels with maximum values of decoherence reduce to
+same value. However, in comparison to phase damping channel, the payoffs of
+cooperators are strongly damped under the influence\ amplitude damping channel
+for\ the lower values of decoherence parameter. In the case of depolarizing
+channel, the game is a no-payoff game irrespective of the degree of
+entanglement in the initial state for the larger values of decoherence
+parameter. The decoherence gets the cooperators worse off.",1701.05342v1
+2017-07-30,Blow-up for semilinear damped wave equations with sub-Strauss exponent in the scattering case,"It is well-known that the critical exponent for semilinear damped wave
+equations is Fujita exponent when the damping is effective. Lai, Takamura and
+Wakasa in 2017 have obtained a blow-up result not only for super-Fujita
+exponent but also for the one closely related to Strauss exponent when the
+damping is scaling invariant and its constant is relatively small,which has
+been recently extended by Ikeda and Sobajima. Introducing a multiplier for the
+time-derivative of the spatial integral of unknown functions, we succeed in
+employing the technics on the analysis for semilinear wave equations and
+proving a blow-up result for semilinear damped wave equations with sub-Strauss
+exponent when the damping is in the scattering range.",1707.09583v3
+2017-10-09,Resonant absorption of surface sausage and surface kink modes under photospheric conditions,"We study the effect of resonant absorption of surface sausage and surface
+kink modes under photospheric conditions where the slow surface sausage modes
+undergo resonant damping in the slow continuum and the surface kink modes in
+the slow and Alfv\'{e}n continua at the transitional layers. We use recently
+derived analytical formulas to obtain the damping rate (time). By considering
+linear density and linear pressure profiles for the transitional layers, we
+show that resonant absorption in the slow continuum could be an efficient
+mechanism for the wave damping of the slow surface sausage and slow surface
+kink modes whilst the damping rate of the slow surface kink mode in the
+Alfv\'{e}n continuum is weak. It is also found that the resonant damping of the
+fast surface kink mode is much stronger than that of the slow surface kink
+mode, showing a similar efficiency as under coronal conditions. It is worth to
+notice that the slow body sausage and kink modes can also resonantly damp in
+the slow continuum for those linear profiles.",1710.03350v2
+2017-11-21,Nonexistence of global solutions of nonlinear wave equations with weak time-dependent damping related to Glassey conjecture,"This work is devoted to the nonexistence of global-in-time energy solutions
+of nonlinear wave equation of derivative type with weak time-dependent damping
+in the scattering and scale invariant range. By introducing some multipliers to
+absorb the damping term, we succeed in establishing the same upper bound of the
+lifespan for the scattering damping as the non-damped case, which is a part of
+so-called Glassey conjecture on nonlinear wave equations. We also study an
+upper bound of the lifespan for the scale invariant damping with the same
+method.",1711.07591v2
+2018-01-03,Stabilisation of wave equations on the torus with rough dampings,"For the damped wave equation on a compact manifold with {\em continuous}
+dampings, the geometric control condition is necessary and sufficient for
+{uniform} stabilisation. In this article, on the two dimensional torus, in the
+special case where $a(x) = \sum\_{j=1}^N a\_j 1\_{x\in R\_j}$ ($R\_j$ are
+polygons), we give a very simple necessary and sufficient geometric condition
+for uniform stabilisation. We also propose a natural generalization of the
+geometric control condition which makes sense for $L^\infty$ dampings. We show
+that this condition is always necessary for uniform stabilisation (for any
+compact (smooth) manifold and any $L^\infty$ damping), and we prove that it is
+sufficient in our particular case on $\mathbb{T}^2$ (and for our particular
+dampings).",1801.00983v2
+2018-03-12,Optical Rotation of Levitated Spheres in High Vacuum,"A circularly polarized laser beam is used to levitate and control the
+rotation of microspheres in high vacuum. At low pressure, rotation frequencies
+as high as 6 MHz are observed for birefringent vaterite spheres, limited by
+centrifugal stresses. Due to the extremely low damping in high vacuum,
+controlled optical rotation of amorphous SiO$_2$ spheres is also observed at
+rates above several MHz. At $10^{-7}$ mbar, a damping time of $6\times10^4$ s
+is measured for a $10\ \mu$m diameter SiO$_2$ sphere. No additional damping
+mechanisms are observed above gas damping, indicating that even longer damping
+times may be possible with operation at lower pressure. The controlled optical
+rotation of microspheres at MHz frequencies with low damping, including for
+materials that are not intrinsically birefringent, provides a new tool for
+performing precision measurements using optically levitated systems.",1803.04297v1
+2018-03-23,A conservation law with spatially localized sublinear damping,"We consider a general conservation law on the circle, in the presence of a
+sublinear damping. If the damping acts on the whole circle, then the solution
+becomes identically zero in finite time, following the same mechanism as the
+corresponding ordinary differential equation. When the damping acts only
+locally in space, we show a dichotomy: if the flux function is not zero at the
+origin, then the transport mechanism causes the extinction of the solution in
+finite time, as in the first case. On the other hand, if zero is a
+non-degenerate critical point of the flux function, then the solution becomes
+extinct in finite time only inside the damping zone, decays algebraically
+uniformly in space, and we exhibit a boundary layer, shrinking with time,
+around the damping zone. Numerical illustrations show how similar phenomena may
+be expected for other equations.",1803.08767v1
+2019-03-06,Microwave magnon damping in YIG films at millikelvin temperatures,"Magnon systems used in quantum devices require low damping if coherence is to
+be maintained. The ferrimagnetic electrical insulator yttrium iron garnet (YIG)
+has low magnon damping at room temperature and is a strong candidate to host
+microwave magnon excitations in future quantum devices. Monocrystalline YIG
+films are typically grown on gadolinium gallium garnet (GGG) substrates. In
+this work, comparative experiments made on YIG waveguides with and without GGG
+substrates indicate that the material plays a significant role in increasing
+the damping at low temperatures. Measurements reveal that damping due to
+temperature-peak processes is dominant above 1 K. Damping behaviour that we
+show can be attributed to coupling to two-level fluctuators (TLFs) is observed
+below 1 K. Upon saturating the TLFs in the substrate-free YIG at 20 mK,
+linewidths of 1.4 MHz are achievable: lower than those measured at room
+temperature.",1903.02527v3
+2020-05-15,Slow magnetosonic wave absorption by pressure induced ionization-recombination dissipation,"A new mechanisms for damping of slow magnetosonic waves (SMW) by pressure
+induced oscillations of the ionization degree is proposed. An explicit formula
+for the damping rate is quantitatively derived. Physical conditions where the
+new mechanism will dominate are briefly discussed. The ionization-recombination
+damping is frequency independent and has no hydrodynamic interpretation.
+Roughly speaking large area of partially ionized plasma are damper for basses
+of SMW while usual MHD mechanisms operate as a low pass filter. The derived
+damping rate is proportional to the square of the sine between the constant
+magnetic field and the wave-vector. Angular distribution of the spectral
+density of SMW and Alfv\'en waves (AW) created by turbulent regions and passing
+through large regions of partially ionized plasma is qualitatively considered.
+The calculated damping rate is expressed by the electron impact cross section
+of the hydrogen atom and in short all details of the proposed damping
+mechanisms are well studied.",2005.07730v1
+2020-07-02,Uniformly-Damped Binomial Filters: Five-percent Maximum Overshoot Optimal Response Design,"In this paper, the five-percent maximum overshoot design of uniformly-damped
+binomial filters (transfer-functions) is introduced. First, the butterworth
+filter response is represented as a damped-binomial filter response. To extend
+the maximum-overshoot response of the second-order butterworth to higher
+orders, the binomial theorem is extended to the uniformly-damped binomial
+theorem. It is shown that the five-percent uniformly-damped binomial filter is
+a compromise between the butterworth filter and the standard binomial filter,
+with respect to the filter-approximation problem in the time and frequency
+domain. Finally, this paper concludes that in applications of interest, such as
+step-tracking, where both strong filtering and a fast, smooth
+transient-response, with negligible overshoot are desired, the response of the
+normalized five-percent uniformly-damped binomial form is a candidate
+replacement for both the butterworth and standard binomial filter forms.",2007.00890v3
+2020-09-17,Temperature Dependent Non-linear Damping in Palladium Nano-mechanical Resonators,"Advances in nano-fabrication techniques has made it feasible to observe
+damping phenomena beyond the linear regime in nano-mechanical systems. In this
+work, we report cubic non-linear damping in palladium nano-mechanical
+resonators. Nano-scale palladium beams exposed to a $H_2$ atmosphere become
+softer and display enhanced Duffing non-linearity as well as non-linear damping
+at ultra low temperatures. The damping is highest at the lowest temperatures of
+$\sim 110\: mK$ and decreases when warmed up-to $\sim 1\textrm{ }K$. We
+experimentally demonstrate for the first time a temperature dependent
+non-linear damping in a nano-mechanical system below 1 K. It is consistent with
+a predicted two phonon mediated non-linear Akhiezer scenario for ballistic
+phonons with mean free path comparable to the beam thickness. This opens up new
+possibilities to engineer non-linear phenomena at low temperatures.",2009.08324v1
+2020-12-25,Information constraint in open quantum systems,"We propose an effect called information constraint which is characterized by
+the existence of different decay rates of signal strengths propagating along
+opposite directions. It is an intrinsic property of a type of open quantum
+system, which does not rely on boundary conditions. We define the value of
+information constraint ($I_C$) as the ratio of different decay rates and derive
+the analytical representation of $I_C$ for general quadratic Lindbladian
+systems. Based on information constraint, we can provide a simple and elegant
+explanation of chiral and helical damping, and get the local maximum points of
+relative particle number for the periodical boundary system, consistent with
+numerical calculations. Inspired by information constraint, we propose and
+prove the correspondence between edge modes and damping modes. A new damping
+mode called Dirac damping is constructed, and chiral/helical damping can be
+regarded as a special case of Dirac damping.",2012.13583v3
+2021-04-29,Non-linear damping of standing kink waves computed with Elsasser variables,"In a previous paper, we computed the energy density and the non-linear energy
+cascade rate for transverse kink waves using Elsasser variables. In this paper,
+we focus on the standing kink waves, which are impulsively excited in coronal
+loops by external perturbations. We present an analytical calculation to
+compute the damping time due to the non-linear development of the
+Kelvin-Helmholtz instability. The main result is that the damping time is
+inversely proportional to the oscillation amplitude. We compare the damping
+times from our formula with the results of numerical simulations and
+observations. In both cases we find a reasonably good match. The comparison
+with the simulations show that the non-linear damping dominates in the high
+amplitude regime, while the low amplitude regime shows damping by resonant
+absorption. In the comparison with the observations, we find a power law
+inversely proportional to the amplitude $\eta^{-1}$ as an outer envelope for
+our Monte Carlo data points.",2104.14331v1
+2021-05-31,Revisiting the Plasmon Radiation Damping of Gold Nanorods,"Noble metal nanoparticles have been utilized for a vast amount of optical
+applications. For the applications that used metal nanoparticles as nanosensors
+and optical labeling, larger radiation damping is preferred (higher optical
+signal). To get a deeper knowledge about the radiation damping of noble metal
+nanoparticles, we used gold nanorods with different geometry factors (aspect
+ratios) as the model system to study. We investigated theoretically how the
+radiation damping of a nanorod depends on the material, and shape of the
+particle. Surprisingly, a simple analytical equation describes radiation
+damping very accurately and allow to disentangle the maximal radiation damping
+parameter for gold nanorod with resonance energy E_res around 1.81 eV (685 nm).
+We found very good agreement with theoretical predictions and experimental data
+obtained by single-particle spectroscopy. Our results and approaches may pave
+the way for designing and optimizing gold nanostructure with higher optical
+signal and better sensing performance.",2105.14873v1
+2021-06-23,Bayesian evidence for a nonlinear damping model for coronal loop oscillations,"Recent observational and theoretical studies indicate that the damping of
+solar coronal loop oscillations depends on the oscillation amplitude. We
+consider two mechanisms, linear resonant absorption and a nonlinear damping
+model. We confront theoretical predictions from these models with observed data
+in the plane of observables defined by the damping ratio and the oscillation
+amplitude. The structure of the Bayesian evidence in this plane displays a
+clear separation between the regions where each model is more plausible
+relative to the other. There is qualitative agreement between the regions of
+high marginal likelihood and Bayes factor for the nonlinear damping model and
+the arrangement of observed data. A quantitative application to 101 loop
+oscillation cases observed with SDO/AIA results in the marginal likelihood for
+the nonlinear model being larger in the majority of them. The cases with
+conclusive evidence for the nonlinear damping model outnumber considerably
+those in favor of linear resonant absorption.",2106.12243v1
+2021-07-13,Convergence of iterates for first-order optimization algorithms with inertia and Hessian driven damping,"In a Hilbert space setting, for convex optimization, we show the convergence
+of the iterates to optimal solutions for a class of accelerated first-order
+algorithms. They can be interpreted as discrete temporal versions of an
+inertial dynamic involving both viscous damping and Hessian-driven damping. The
+asymptotically vanishing viscous damping is linked to the accelerated gradient
+method of Nesterov while the Hessian driven damping makes it possible to
+significantly attenuate the oscillations. By treating the Hessian-driven
+damping as the time derivative of the gradient term, this gives, in discretized
+form, first-order algorithms. These results complement the previous work of the
+authors where it was shown the fast convergence of the values, and the fast
+convergence towards zero of the gradients.",2107.05943v1
+2021-12-13,Effect of interfacial damping on high-frequency surface wave resonance on a nanostrip-bonded substrate,"Since surface acoustic waves (SAW) are often generated on substrates to which
+nanostrips are periodically attached, it is very important to consider the
+effect of interface between the deposited strip and the substrate surface,
+which is an unavoidable issue in manufacturing. In this paper, we propose a
+theoretical model that takes into account the interface damping and calculate
+the dispersion relationships both for frequency and attenuation of SAW
+resonance. This results show that the interface damping has an insignificant
+effect on resonance frequency, but, interestingly, attenuation of the SAW can
+decrease significantly in the high frequency region as the interface damping
+increases. Using picosecond ultrasound spectroscopy, we confirm the validity of
+our theory; the experimental results show similar trends both for resonant
+frequency and attenuation in the SAW resonance. Furthermore, the resonant
+behavior of the SAW is simulated using the finite element method, and the
+intrinsic cause of interface damping on the vibrating system is discussed.
+These findings strongly indicate the necessity of considering interfacial
+damping in the design of SAW devices.",2112.06367v1
+2022-09-13,Latest results from the DAMPE space mission,"The DArk Matter Particle Explorer (DAMPE) is a space-based particle detector
+launched on December 17th, 2015 from the Jiuquan Satellite Launch Center
+(China). The main goals of the DAMPE mission are the study of galactic cosmic
+rays (CR), the electron-positron energy spectrum, gamma-ray astronomy, and
+indirect dark matter search. Among its sub-detectors, the deep calorimeter
+makes DAMPE able to measure electrons and gamma-ray spectra up to 10 TeV, and
+CR nuclei spectra up to hundreds of TeV, with unprecedented energy resolution.
+This high-energy region is important in order to search for electron-positron
+sources, for dark matter signatures in space, and to clarify CR acceleration
+and propagation mechanisms inside our galaxy. A general overview of the DAMPE
+experiment will be presented in this work, along with its main results and
+ongoing activities.",2209.06014v1
+2022-10-25,Microscopic structure of electromagnetic whistler wave damping by kinetic mechanisms in hot magnetized Vlasov plasmas,"The kinetic damping mechanism of low frequency transverse perturbations
+propagating parallel to the magnetic field in a magnetized warm electron plasma
+is simulated by means of electromagnetic (EM) Vlasov simulations. The
+short-time-scale damping of the electron magnetohydrodynamic whistler
+perturbations and underlying physics of finite electron temperature effect on
+its real frequency are recovered rather deterministically, and analyzed. The
+damping arises from an interplay between a global (prevailing over entire
+phase-space) and the more familiar resonant-electron-specific kinetic damping
+mechanisms, both of which preserve entropy but operate distinctly by leaving
+their characteristic signatures on an initially coherent finite amplitude
+modification of the warm electron equilibrium distribution. The net damping
+results from a deterministic thermalization, or phase-mixing process, largely
+supplementing the resonant acceleration of electrons at shorter time scales,
+relevant to short-lived turbulent EM fluctuations. A kinetic model for the
+evolving initial transverse EM perturbation is presented and applied to
+signatures of the whistler wave phase-mixing process in simulations.",2210.13764v1
+2023-01-13,An artificially-damped Fourier method for dispersive evolution equations,"Computing solutions to partial differential equations using the fast Fourier
+transform can lead to unwanted oscillatory behavior. Due to the periodic nature
+of the discrete Fourier transform, waves that leave the computational domain on
+one side reappear on the other and for dispersive equations these are typically
+high-velocity, high-frequency waves. However, the fast Fourier transform is a
+very efficient numerical tool and it is important to find a way to damp these
+oscillations so that this transform can still be used. In this paper, we
+accurately model solutions to four nonlinear partial differential equations on
+an infinite domain by considering a finite interval and implementing two
+damping methods outside of that interval: one that solves the heat equation and
+one that simulates rapid exponential decay. Heat equation-based damping is best
+suited for small-amplitude, high-frequency oscillations while exponential decay
+is used to damp traveling waves and high-amplitude oscillations. We demonstrate
+significant improvements in the runtime of well-studied numerical methods when
+adding in the damping method.",2301.05789v1
+2023-03-07,Stabilization of the wave equation on larger-dimension tori with rough dampings,"This paper deals with uniform stabilization of the damped wave equation. When
+the manifold is compact and the damping is continuous, the geometric control
+condition is known to be necessary and sufficient. In the case where the
+damping is a sum of characteristic functions of polygons on a two-dimensional
+torus, a result by Burq-G\'erard states that stabilization occurs if and only
+if every geodesic intersects the interior of the damped region or razes damped
+polygons on both sides. We give a natural generalization of their result to a
+sufficient condition on tori of any dimension $d \geq 3$. In some particular
+cases, we show that this sufficient condition can be weakened.",2303.03733v4
+2023-07-10,The Characteristic Shape of Damping Wings During Reionization,"Spectroscopic analysis of Ly$\alpha$ damping wings of bright sources at $z>6$
+is a promising way to measure the reionization history of the universe.
+However, the theoretical interpretation of the damping wings is challenging due
+to the inhomogeneous nature of the reionization process and the proximity
+effect of bright sources. In this Letter, we analyze the damping wings arising
+from the neutral patches in the radiative transfer cosmological simulation
+suite Cosmic Reionization on Computers (CROC). We find that the damping wing
+profile remains a tight function of volume-weighted neutral fraction $\left<
+x_{\rm HI} \right>_{\rm v}$, especially when $\left< x_{\rm HI} \right>_{\rm
+v}>0.5$, despite the patchy nature of reionization and the proximity effect.
+This small scatter indicates that with a well-measured damping wing profile, we
+could constrain the volume-weighted neutral fraction as precise as $\Delta
+\left< x_{\rm HI} \right>_{\rm v} \lesssim 0.1$ in the first half of
+reionization.",2307.04797v1
+2023-07-17,Dissipation in solids under oscillatory shear: Role of damping scheme and sample thickness,"We study dissipation as a function of sample thickness in solids under global
+oscillatory shear applied to the top layer of the sample. Two types of damping
+mechanism are considered: Langevin and Dissipative Particle Dynamics (DPD). In
+the regime of low driving frequency, and under strain-controlled conditions, we
+observe that for Langevin damping, dissipation increases with sample thickness,
+while for DPD damping, it decreases. Under force-controlled conditions,
+dissipation increases with sample thickness for both damping schemes. These
+results can be physically understood by treating the solid as a one-dimensional
+harmonic chain in the quasi-static limit, for which explicit equations (scaling
+relations) describing dissipation as a function of chain length (sample
+thickness) are provided. The consequences of these results, in particular
+regarding the choice of damping scheme in computer simulations, are discussed.",2307.08413v1
+2023-08-17,A low-rank algorithm for strongly damped wave equations with visco-elastic damping and mass terms,"Damped wave equations have been used in many real-world fields. In this
+paper, we study a low-rank solution of the strongly damped wave equation with
+the damping term, visco-elastic damping term and mass term. Firstly, a
+second-order finite difference method is employed for spatial discretization.
+Then, we receive a second-order matrix differential system. Next, we transform
+it into an equivalent first-order matrix differential system, and split the
+transformed system into three subproblems. Applying a Strang splitting to these
+subproblems and combining a dynamical low-rank approach, we obtain a low-rank
+algorithm. Numerical experiments are reported to demonstrate that the proposed
+low-rank algorithm is robust and accurate, and has second-order convergence
+rate in time.",2308.08888v2
+2023-10-30,Optimal backward uniqueness and polynomial stability of second order equations with unbounded damping,"For general second order evolution equations, we prove an optimal condition
+on the degree of unboundedness of the damping, that rules out finite-time
+extinction. We show that control estimates give energy decay rates that
+explicitly depend on the degree of unboundedness, and establish a dilation
+method to turn existing control estimates for one propagator into those for
+another in the functional calculus. As corollaries, we prove Schr\""odinger
+observability gives decay for unbounded damping, weak monotonicity in damping,
+and quantitative unique continuation and optimal propagation for fractional
+Laplacians. As applications, we establish a variety of novel and explicit
+energy decay results to systems with unbounded damping, including singular
+damping, linearised gravity water waves and Euler--Bernoulli plates.",2310.19911v1
+2024-03-12,"Modulational instability of nonuniformly damped, broad-banded waves: applications to waves in sea-ice","This paper sets out to explore the modulational (or Benjamin-Feir)
+instability of a monochromatic wave propagating in the presence of damping such
+as that induced by sea-ice on the ocean surface. The fundamental wave motion is
+modelled using the spatial Zakharov equation, to which either uniform or
+non-uniform (frequency dependent) damping is added. By means of mode truncation
+the spatial analogue of the classical Benjamin-Feir instability can be studied
+analytically using dynamical systems techniques. The formulation readily yields
+the free surface envelope, giving insight into the physical implications of
+damping on the modulational instability. The evolution of an initially unstable
+mode is also studied numerically by integrating the damped, spatial Zakharov
+equation, in order to complement the analytical theory. This sheds light on the
+effects of damping on spectral broadening arising from this instability.",2403.07425v1
+1994-05-12,Black Hole Relics and Inflation: Limits on Blue Perturbation Spectra,"Blue primordial power spectra have spectral index $n>1$ and arise naturally
+in the recently proposed hybrid inflationary scenario. An observational upper
+limit on {\em n} is derived by normalizing the spectrum at the quadrupole scale
+and considering the possible overproduction of Planck mass relics formed in the
+final stage of primordial black hole evaporation. In the inflationary Universe
+with the maximum reheating temperature compatible with the observed quadrupole
+anisotropy, the upper limit is $n=1.4$, but it is slightly weaker for lower
+reheat temperatures. This limit applies over 57 decades of mass and is
+therefore insensitive to cosmic variance and any gravitational wave
+contribution to the quadrupole anisotropy. It is also independent of the dark
+matter content of the Universe and therefore the bias parameter. In some
+circumstances, there may be an extended dust-like phase between the end of
+inflation and reheating. In this case, primordial black holes form more
+abundantly and the upper limit is $n=1.3$.",9405027v1
+1995-02-01,Spectra and Statistics of Cosmic String Perturbations on the Microwave Background: A Monte Carlo Approach,"Using Monte Carlo simulations of perturbations induced by cosmic strings on
+the microwave background, we demonstrate the scale invariance of string
+fluctuation patterns. By comparing string-induced fluctuation patterns with
+gaussian random phase ones, we show that the non-gaussian signatures of the
+string patterns are detectable by tests based on the moments of the
+distributions only for angular scales smaller than a few arcminutes and for
+maps based on the gradient of temperature fluctuations. However, we find that
+tests of the gaussianity of the moments fail when we include a reasonable
+amount of instrumental noise in a pattern. Signal to noise ratios of $3.3$ or
+greater completely suppress a string pattern's non-gaussian features even at
+the highest resolutions.",9502004v2
+1999-04-16,The Sunyaev-Zeldovich Effect as Microwave Foreground and Probe of Cosmology,"The Sunyaev-Zel'dovich (SZ) effect from clusters of galaxies should yield a
+significant signal in cosmic microwave background(CMB) experiments at small
+angular scales ($\ell \ga 1000$). Experiments with sufficient frequency
+coverage should be able to remove much of this signal in order to recover the
+primary anisotropy. The SZ signal is interesting in its own right; the
+amplitude and angular dependence are sensitive to both cosmology and the
+evolution of the gas. Combining CMB measurements with planned non-targeted SZ
+surveys could isolate the cosmological effects, providing CMB experiments with
+a low-redshift test of cosmology as a consistency check. Improvements in the
+determination of the angular diameter distance as a function of redshift from
+SZ and X-ray observations of a large sample of clusters will also provide a
+probe of cosmology.",9904220v1
+2000-12-05,Near-IR Spectroscopy and Population Synthesis of Super Star Clusters in NGC 1569,"We present H- and K-band NIRSPEC spectroscopy of super star clusters (SSCs)
+in the irregular starburst galaxy NGC 1569, obtained at the Keck Observatory.
+We fit these photospheric spectra to NextGen model atmospheres to obtain
+effective spectral types of clusters, and find that the information in both H-
+and K-band spectra is necessary to remove degeneracy in the fits. The light of
+SSC B is unambiguously dominated by K0 supergiants (T_eff=4400 +- 100 K, log
+g=0.5 +- 0.5). The double cluster SSC A has higher T_eff (G5) and less tightly
+constrained surface gravity (log g=1.3 +- 1.3), consistent with a mixed stellar
+population dominated by blue Wolf-Rayet stars and red supergiants. We predict
+the time evolution of infrared spectra of SSCs using Starburst99 population
+synthesis models coupled with empirical stellar spectral libraries (at solar
+metallicity). The resulting model sequence allows us to assign ages of 15-18
+Myr for SSC B and 18-21 Myr for SSC A.",0012089v1
+2001-05-14,Understanding Cluster Gas Evolution and Fine-Scale CMB Anisotropy with Deep Sunyaev-Zel'dovich Effect Surveys,"We investigate the impact of gas evolution on the expected yields from deep
+Sunyaev-Zel'dovich (SZ) effect surveys as well as on the expected SZ effect
+contribution to fine scale anisotropy in the Cosmic Microwave Background. The
+approximate yields from SZ effect surveys are remarkably insensitive to gas
+evolution, even though the observable properties of the resulting clusters can
+be markedly different. The CMB angular power spectrum at high multipoles due to
+the SZ effect from clusters is quite sensitive to gas evolution. We show that
+moderate resolution SZ effect imaging of clusters found in deep SZ effect
+surveys should allow a good understanding of gas evolution in galaxy clusters,
+independent of the details of the nature of the gas evolution. Such an
+understanding will be necessary before precise cosmological constraints can be
+set from yields of large cluster surveys.",0105229v1
+2001-05-22,"Constraints on Omega_m, Omega_L, and Sigma_8, from Galaxy Cluster Redshift Distributions","We show that the counts of galaxy clusters in future deep cluster surveys can
+place strong constraints on the matter density, Omega_m, the vacuum energy
+density, Omega_L, and the normalization of the matter power spectrum, sigma_8.
+Degeneracies between these parameters are different from those in studies of
+either high--redshift type Ia Supernovae (SNe), or cosmic microwave background
+(CMB) anisotropies. Using a mass threshold for cluster detection expected to be
+typical for upcoming SZE surveys, we find that constraints on Omega_m and
+sigma_8 at the level of roughly 5% or better can be expected, assuming redshift
+information is known at least to z=0.5 and in the absence of significant
+systematic errors. Without information past this redshift, Omega_L is
+constrained to 25%. With complete redshift information, deep (M_{lim}=
+10^{14}h^{-1}{M_sun}), relatively small solid angle (roughly 12 {deg}^2)
+surveys can further constrain Omega_L to an accuracy of 15%, while large solid
+angle surveys with ground-based large-format bolometer arrays could measure
+Omega_L to a precision of 4% or better.",0105396v2
+2002-05-27,Radio Point Sources and the Thermal SZ Power Spectrum,"Radio point sources are strongly correlated with clusters of galaxies, so a
+significant fraction of the thermal Sunyaev-Zel'dovich (SZ) effect signal could
+be affected by point source contamination. Based on empirical estimates of the
+radio galaxy population, it is shown that the rms temperature fluctuations of
+the thermal SZ effect could be underestimated by as much as 30% at an observing
+frequency of 30 GHz at l>1000. The effect is larger at higher multipoles. If
+the recent report of excess power at small angular scales is to be explained by
+the thermal SZ effect, then radio point sources at an observing frequency of 30
+GHz must be a surprisingly weak contaminant of the SZ effect for low-mass
+clusters.",0205467v2
+2002-07-29,Measuring Cluster Peculiar Velocities and Temperatures at cm and mm Wavelengths,"We present a detailed investigation of issues related to the measurement of
+peculiar velocities and temperatures using Sunyaev-Zel'dovich (SZ) effects. We
+estimate the accuracy to which peculiar velocities and gas temperatures of
+distant galaxy clusters could be measured. With uK sensitivity on arcminute
+scales at several frequencies it will be possible to measure peculiar
+velocities to an accuracy of about 130 km/s and gas temperatures to better than
+1 keV. The limiting factor for the accuracy of the measured peculiar velocity
+is the presence of bulk motions within the galaxy cluster, even for apparently
+relaxed clusters. The accuracy of the temperature is mainly limited by noise.
+These results are independent of redshift. Such constraints can best be
+achieved with only three frequencies: one in the Rayleigh-Jeans region (<40
+GHz), one near 150 GHz, and the third at 300 GHz or higher. Measurements at the
+null of the thermal SZ effect are of marginal utility, other than as a
+foreground/background monitor.",0207600v2
+2002-07-29,CMB-Normalized Predictions for Sunyaev-Zel'dovich effect fluctuations,"We predict the level of small-scale anisotropy in the cosmic microwave
+background (CMB) due to the Sunyaev--Zel'dovich (SZ) effect for the ensemble of
+cosmological models that are consistent with current measurements of
+large-scale CMB anisotropy. We argue that the recently reported detections of
+the small-scale (arcminutes) CMB anisotropy are only marginally consistent with
+being the SZ effect when cosmological models are calibrated to the existing
+primary CMB data on large scales. The discrepancy is at more than 2-2.5 sigma,
+and is mainly due to a lower sigma_8 <0.8 favored by the primary CMB and a
+higher sigma_8 > 1 favored by the SZ effect. A degeneracy between the optical
+depth to Thomson scattering and the CMB-derived value of sigma_8 suggests that
+the discrepancy is reduced if the universe was reionized very early, at a
+redshift of about 25.",0207633v1
+2002-08-08,Cosmology with the Sunyaev-Zel'dovich Effect,"The Sunyaev-Zel'dovich effect (SZE) provides a unique way to map the
+large-scale structure of the universe as traced by massive clusters of
+galaxies. As a spectral distortion of the cosmic microwave background, the SZE
+is insensitive to the redshift of the galaxy cluster, making it well-suited for
+studies of clusters at all redshifts, and especially at reasonably high
+redshifts (z > 1) where the abundance of clusters is critically dependent on
+the underlying cosmology. Recent high signal-to-noise detections of the SZE
+have enabled interesting constraints on the Hubble constant and the matter
+density of the universe using small samples of galaxy clusters. Upcoming SZE
+surveys are expected to find hundreds to thousands of new galaxy clusters, with
+a mass selection function that is remarkably uniform with redshift. In this
+review we provide an overview of the SZE and its use for cosmological studies
+with emphasis on the cosmology that can, in principle, be extracted from SZE
+survey yields. We discuss the observational and theoretical challenges that
+must be met before precise cosmological constraints can be extracted from the
+survey yields.",0208192v1
+2002-09-25,External Shear in Quadruply Imaged Lens Systems,"We use publicly available N-body simulations and semi-analytic models of
+galaxy formation to estimate the levels of external shear due to structure near
+the lens in gravitational lens systems. We also describe two selection effects,
+specific to four-image systems, that enhance the probability of observing
+systems to have higher external shear. Ignoring additional contributions from
+""cosmic shear"" and assuming that lens galaxies are not significantly flattened,
+we find that the mean shear at the position of a quadruple lens galaxy is 0.11,
+the rms shear is roughly 0.15, and there is roughly a 45% likelihood of
+external shear greater than 0.1. This is much larger than previous estimates
+and in good agreement with typical measured external shear. The higher shear
+primarily stems from the tendency of early-type galaxies, which are the
+majority of lenses, to reside in overdense regions.",0209532v2
+2003-05-21,A Method for Mapping the Temperature Profile of X-ray Clusters Through Radio Observations,"Many of the most luminous extragalactic radio sources are located at the
+centers of X-ray clusters, and so their radiation must be scattered by the
+surrounding hot gas. We show that radio observations of the highly-polarized
+scattered radiation (which depends on the electron density distribution) in
+combination with the thermal Sunyaev-Zeldovich effect (which measures the
+electron pressure distribution), can be used to determine the radial profile of
+the electron temperature within the host cluster. The sensitivity levels
+expected from current instruments will allow radio measurements of
+mass-weighted cluster temperature profiles to better than roughly 1 keV
+accuracy, as long as the central radio source is steady over several million
+years. Variable or beamed sources will leave observable signatures in the
+scattered emission. For clusters with a central point source brighter than
+about 1 mJy, the scattered polarization signal is stronger than competing
+effects due to the cosmic microwave background.",0305417v1
+2006-09-26,Reconstructing the Thomson Optical Depth due to Patchy Reionization with 21-cm Fluctuation Maps,"Large fluctuations in the electron column density can occur during the
+reionization process. We investigate the possibility of deriving the electron
+density fluctuations through detailed mapping of the redshifted 21-cm emission
+from the neutral medium during reionization. We find that the
+electron-scattering optical depth and 21-cm differential brightness temperature
+are strongly anti-correlated, allowing optical depth estimates based entirely
+on redshifted 21-cm measurements. This should help isolate the CMB polarization
+fluctuations that are due to reionization, allowing both cleaning of the patchy
+reionization polarization signal as a contaminating source of confusion to
+other signals and a measurement of the primordial quadrupole that would be
+measured at various locations in the universe at the epoch of reionization.
+This latter application in principle allows mapping of the primordial density
+field at z~1100 over a large fraction of the Hubble volume.",0609689v2
+1998-07-06,Field Driven Thermostated System : A Non-Linear Multi-Baker Map,"In this paper, we discuss a simple model for a field driven, thermostated
+random walk that is constructed by a suitable generalization of a multi-baker
+map. The map is a usual multi-baker, but perturbed by a thermostated external
+field that has many of the properties of the fields used in systems with
+Gaussian thermostats. For small values of the driving field, the map is
+hyperbolic and has a unique SRB measure that we solve analytically to first
+order in the field parameter. We then compute the positive and negative
+Lyapunov exponents to second order and discuss their relation to the transport
+properties. For higher values of the parameter, this system becomes
+non-hyperbolic and posseses an attractive fixed point.",9807011v2
+2006-01-19,Fluctuation theorem for constrained equilibrium systems,"We discuss the fluctuation properties of equilibrium chaotic systems with
+constraints such as iso-kinetic and Nos\'e-Hoover thermostats. Although the
+dynamics of these systems does not typically preserve phase-space volumes, the
+average phase-space contraction rate vanishes, so that the stationary states
+are smooth. Nevertheless finite-time averages of the phase-space contraction
+rate have non-trivial fluctuations which we show satisfy a simple version of
+the Gallavotti-Cohen fluctuation theorem, complementary to the usual
+fluctuation theorem for non-equilibrium stationary states, and appropriate to
+constrained equilibrium states. Moreover we show these fluctuations are
+distributed according to a Gaussian curve for long-enough times. Three
+different systems are considered here, namely (i) a fluid composed of particles
+interacting with Lennard-Jones potentials; (ii) a harmonic oscillator with
+Nos\'e-Hoover thermostatting; (iii) a simple hyperbolic two-dimensional map.",0601435v1
+2003-06-12,ATLAS Data Challenge 1,"In 2002 the ATLAS experiment started a series of Data Challenges (DC) of
+which the goals are the validation of the Computing Model, of the complete
+software suite, of the data model, and to ensure the correctness of the
+technical choices to be made. A major feature of the first Data Challenge (DC1)
+was the preparation and the deployment of the software required for the
+production of large event samples for the High Level Trigger (HLT) and physics
+communities, and the production of those samples as a world-wide distributed
+activity. The first phase of DC1 was run during summer 2002, and involved 39
+institutes in 18 countries. More than 10 million physics events and 30 million
+single particle events were fully simulated. Over a period of about 40 calendar
+days 71000 CPU-days were used producing 30 Tbytes of data in about 35000
+partitions. In the second phase the next processing step was performed with the
+participation of 56 institutes in 21 countries (~ 4000 processors used in
+parallel). The basic elements of the ATLAS Monte Carlo production system are
+described. We also present how the software suite was validated and the
+participating sites were certified. These productions were already partly
+performed by using different flavours of Grid middleware at ~ 20 sites.",0306052v1
+2004-06-21,Long Nonbinary Codes Exceeding the Gilbert - Varshamov Bound for any Fixed Distance,"Let A(q,n,d) denote the maximum size of a q-ary code of length n and distance
+d. We study the minimum asymptotic redundancy \rho(q,n,d)=n-log_q A(q,n,d) as n
+grows while q and d are fixed. For any d and q<=d-1, long algebraic codes are
+designed that improve on the BCH codes and have the lowest asymptotic
+redundancy \rho(q,n,d) <= ((d-3)+1/(d-2)) log_q n known to date. Prior to this
+work, codes of fixed distance that asymptotically surpass BCH codes and the
+Gilbert-Varshamov bound were designed only for distances 4,5 and 6.",0406039v3
+2006-08-19,Algorithmic linear dimension reduction in the l_1 norm for sparse vectors,"This paper develops a new method for recovering m-sparse signals that is
+simultaneously uniform and quick. We present a reconstruction algorithm whose
+run time, O(m log^2(m) log^2(d)), is sublinear in the length d of the signal.
+The reconstruction error is within a logarithmic factor (in m) of the optimal
+m-term approximation error in l_1. In particular, the algorithm recovers
+m-sparse signals perfectly and noisy signals are recovered with polylogarithmic
+distortion. Our algorithm makes O(m log^2 (d)) measurements, which is within a
+logarithmic factor of optimal. We also present a small-space implementation of
+the algorithm. These sketching techniques and the corresponding reconstruction
+algorithms provide an algorithmic dimension reduction in the l_1 norm. In
+particular, vectors of support m in dimension d can be linearly embedded into
+O(m log^2 d) dimensions with polylogarithmic distortion. We can reconstruct a
+vector from its low-dimensional sketch in time O(m log^2(m) log^2(d)).
+Furthermore, this reconstruction is stable and robust under small
+perturbations.",0608079v1
+2007-03-06,LIBOPT - An environment for testing solvers on heterogeneous collections of problems - Version 1.0,"The Libopt environment is both a methodology and a set of tools that can be
+used for testing, comparing, and profiling solvers on problems belonging to
+various collections. These collections can be heterogeneous in the sense that
+their problems can have common features that differ from one collection to the
+other. Libopt brings a unified view on this composite world by offering, for
+example, the possibility to run any solver on any problem compatible with it,
+using the same Unix/Linux command. The environment also provides tools for
+comparing the results obtained by solvers on a specified set of problems. Most
+of the scripts going with the Libopt environment have been written in Perl.",0703025v1
+1995-09-19,Harmonic Maps with Prescribed Singularities on Unbounded Domains,"The Einstein/Abelian-Yang-Mills Equations reduce in the stationary and
+axially symmetric case to a harmonic map with prescribed singularities
+$\p\colon\R^3\sm\Sigma\to\H^{k+1}_\C$ into the $(k+1)$-dimensional complex
+hyperbolic space. In this paper, we prove the existence and uniqueness of
+harmonic maps with prescribed singularities $\p\colon\R^n\sm\Sigma\to\H$, where
+$\Sigma$ is an unbounded smooth closed submanifold of $\R^n$ of codimension at
+least $2$, and $\H$ is a real, complex, or quaternionic hyperbolic space. As a
+corollary, we prove the existence of solutions to the reduced stationary and
+axially symmetric Einstein/Abelian-Yang-Mills Equations.",9509003v1
+1994-12-12,N-Black Hole Stationary and Axially Symmetric Solutions of the Einstein-Maxwell Equations,"The Einstein/Maxwell equations reduce in the stationary and axially symmetric
+case to a harmonic map with prescribed singularities phi: R^3\Sigma -> H^2_C,
+where Sigma is a subset of the axis of symmetry, and H^2_C is the complex
+hyperbolic plane. Motivated by this problem, we prove the existence and
+uniqueness of harmonic maps with prescribed singularities phi: R^n\Sigma -> H,
+where Sigma is a submanifold of R^n of co-dimension at least 2, and H is a
+classical Riemannian globally symmetric space of noncompact type and rank one.
+This result, when applied to the black hole problem, yields solutions which can
+be interpreted as equilibrium configurations of multiple co-axially rotating
+charged black holes held apart by singular struts.",9412036v2
+1997-11-17,Novel Electroweak Symmetry Breaking Conditions From Quantum Effects In The MSSM,"We present, in the context of the Minimal Supersymmetric Standard Model, a
+detailed one-loop analytic study of the minimization conditions of the
+effective potential in the Higgs sector.
+  Special emphasis is put on the role played by $Str M^4$ in the determination
+of the electroweak symmetry breaking conditions, where first and second order
+derivatives of the effective potential are systematically taken into account.
+Novel, necessary (and sufficient in the Higgs sector) model-independent
+constraints, are thus obtained analytically, leading to new theoretical lower
+and upper bounds on $\tan \beta$. Although fully model-independent, these
+bounds are found to be much more restrictive than the existing model-dependent
+ones! A first illustration is given in the context of a SUGRA-GUT motivated
+scenario.",9711356v1
+1999-01-08,On the fourth adjoint Contractions of divisorial and fiber types,"In this paper, we will list up all the cases for the ray contractions of
+divisorial and fiber types for smooth projective varieties of dimension five.
+These are obtained as a corollary from the lists of n-dimensional k-th adjoint
+contractions f: X -> Y of the same types for k=1,2,3 and 4 (n> or =5). The
+lists for k=1,2 and 3 have previously been obtained in [Na], Proposition 1.2
+and Theorem 1.3. The main task will be to have such a list for k=4, where one
+case in the list fails to show that a positive-dimensional general fiber F of f
+is irreducible when n>5. This assertion will, however, be proven when n=5 with
+an essential aid of 3-dimensional Minimal Model Program in [Mo2]. (We do not
+show the existence of cases.)",9901033v2
+2004-04-19,Asymptotic Improvement of the Gilbert-Varshamov Bound on the Size of Binary Codes,"Given positive integers $n$ and $d$, let $A_2(n,d)$ denote the maximum size
+of a binary code of length $n$ and minimum distance $d$. The well-known
+Gilbert-Varshamov bound asserts that $A_2(n,d) \geq 2^n/V(n,d-1)$, where
+$V(n,d) = \sum_{i=0}^{d} {n \choose i}$ is the volume of a Hamming sphere of
+radius $d$. We show that, in fact, there exists a positive constant $c$ such
+that $$ A_2(n,d) \geq c \frac{2^n}{V(n,d-1)} \log_2 V(n,d-1) $$ whenever $d/n
+\le 0.499$. The result follows by recasting the Gilbert- Varshamov bound into a
+graph-theoretic framework and using the fact that the corresponding graph is
+locally sparse. Generalizations and extensions of this result are briefly
+discussed.",0404325v1
+2005-11-03,On the automorphism group of generalized Baumslag-Solitar groups,"A generalized Baumslag-Solitar group (GBS group) is a finitely generated
+group $G$ which acts on a tree with all edge and vertex stabilizers infinite
+cyclic. We show that Out(G) either contains non-abelian free groups or is
+virtually nilpotent of class at most 2. It has torsion only at finitely many
+primes.
+  One may decide algorithmically whether Out(G) is virtually nilpotent or not.
+If it is, one may decide whether it is virtually abelian, or finitely
+generated. The isomorphism problem is solvable among GBS groups with Out(G)
+virtually nilpotent.
+  If $G$ is unimodular (virtually $F_n \times Z$), then Out(G) is commensurable
+with a semi-direct product $Z^k \rtimes Out(H)$ with $H$ virtually free.",0511083v1
+2001-07-08,Statistically Preserved Structures in Shell Models of Passive Scalar Advection,"It was conjectured recently that Statiscally Preserved Structures underlie
+the statistical physics of turbulent transport processes. We analyze here in
+detail the time-dependent (non compact) linear operator that governs the
+dynamics of correlation functions in the case of shell models of passive scalar
+advection. The problem is generic in the sense that the driving velocity field
+is neither Gaussian nor $\delta$-correlated in time. We show how to naturally
+discuss the dynamics in terms of an effective compact operator that displays
+""zero modes"" which determine the anomalous scaling of the correlation
+functions. Since shell models have neither Lagrangian structure nor ""shape
+dynamics"" this example differs significantly from standard passive scalar
+advection. Nevertheless with the necessary modifications the generality and
+efficacy of the concept of Statistically Preserved Structures are further
+exemplified. In passing we point out a bonus of the present approach, in
+providing analytic predictions for the time-dependent correlation functions in
+decaying turbulent transport.",0107016v1
+2001-11-13,Statistically Preserved Structures and Anomalous Scaling in Turbulent Active Scalar Advection,"The anomalous scaling of correlation functions in the turbulent statistics of
+active scalars (like temperature in turbulent convection) is understood in
+terms of an auxiliary passive scalar which is advected by the same turbulent
+velocity field. While the odd-order correlation functions of the active and
+passive fields differ, we propose that the even-order correlation functions are
+the same to leading order (up to a trivial multiplicative factor). The leading
+correlation functions are statistically preserved structures of the passive
+scalar decaying problem, and therefore universality of the scaling exponents of
+the even-order correlations of the active scalar is demonstrated.",0111030v1
+2003-03-27,On the parametric dependences of a class of non-linear singular maps,"We discuss a two-parameter family of maps that generalize piecewise linear,
+expanding maps of the circle. One parameter measures the effect of a
+non-linearity which bends the branches of the linear map. The second parameter
+rotates points by a fixed angle. For small values of the nonlinearity
+parameter, we compute the invariant measure and show that it has a singular
+density to first order in the nonlinearity parameter. Its Fourier modes have
+forms similar to the Weierstrass function. We discuss the consequences of this
+singularity on the Lyapunov exponents and on the transport properties of the
+corresponding multibaker map. For larger non-linearities, the map becomes
+non-hyperbolic and exhibits a series of period-adding bifurcations.",0303062v1
+2001-06-06,The Secrecy Capacity of Practical Quantum Cryptography,"Quantum cryptography has attracted much recent attention due to its potential
+for providing secret communications that cannot be decrypted by any amount of
+computational effort. This is the first analysis of the secrecy of a practical
+implementation of the BB84 protocol that simultaneously takes into account and
+presents the {\it full} set of complete analytical expressions for effects due
+to the presence of pulses containing multiple photons in the attenuated output
+of the laser, the finite length of individual blocks of key material, losses
+due to error correction, privacy amplification, continuous authentication,
+errors in polarization detection, the efficiency of the detectors, and
+attenuation processes in the transmission medium. The analysis addresses
+eavesdropping attacks on individual photons rather than collective attacks in
+general. Of particular importance is the first derivation of the necessary and
+sufficient amount of privacy amplification compression to ensure secrecy
+against the loss of key material which occurs when an eavesdropper makes
+optimized individual attacks on pulses containing multiple photons. It is shown
+that only a fraction of the information in the multiple photon pulses is
+actually lost to the eavesdropper.",0106033v1
+2005-11-17,"Quantum Computer Condition: Stability, Classical Computation and Norms","The Quantum Computer Condition (QCC) provides a rigorous and completely
+general framework for carrying out analyses of questions pertaining to
+fault-tolerance in quantum computers. In this paper we apply the QCC to the
+problem of fluctuations and systematic errors in the values of characteristic
+parameters in realistic systems. We show that fault-tolerant quantum
+computation is possible despite variations in these parameters. We also use the
+QCC to explicitly show that reliable classical computation can be carried out
+using as input the results of fault-tolerant, but imperfect, quantum
+computation. Finally, we consider the advantages and disadvantages of the
+superoperator and diamond norms in connection with application of the QCC to
+various quantum information-theoretic problems.",0511177v1
+2006-12-19,On the use of photonic N00N states for practical quantum interferometry,"The performance of photonic $N00N$ states, propagating in an attenuating
+medium, is analyzed with respect to phase estimation. It is shown that, for
+$N00N$ states propagating through a lossy medium, the Heisenberg limit is never
+achieved. It is also shown that, for a given value of $N$, a signal comprised
+of an attenuated separable state of $N$ photons will actually produce a better
+phase estimate than will a signal comprised of an equally attenuated $N00N$
+state, unless the transmittance of the medium is very high. This is a
+consequence of the need to utilize measurement operators appropriate to the
+different signal states. The result is that, for most practical applications in
+realistic scenarios with attenuation, the resolution of $N00N$ state-based
+phase estimation not only does not achieve the Heisenberg Limit, but is
+actually worse than the Standard Quantum Limit. It is demonstrated that this
+performance deficit becomes more pronounced as the number, $N$, of photons in
+the signal increases.",0612156v1
+2007-05-22,Analysis of evidence of Mars life,"Gillevinia straata, the scientific name [1, 2] recognizing the first
+extraterrestrial living form ever nomenclated, as well as the existence of a
+new biological kingdom, Jakobia, in a new biosphere -Marciana- of what now has
+become the living system Solaria, is grounded on old evidence reinterpreted in
+the light of newly acquired facts. The present exposition provides a summary
+overview of all these grounds, outlined here as follows. A more detailed paper
+is being prepared for publication.",0705.3176v3
+2007-06-26,Feedback in the Antennae Galaxies (NGC 4038/9): I. High-Resolution Infrared Spectroscopy of Winds from Super Star Clusters,"We present high-resolution (R ~ 24,600) near-IR spectroscopy of the youngest
+super star clusters (SSCs) in the prototypical starburst merger, the Antennae
+Galaxies. These SSCs are young (3-7 Myr old) and massive (10^5 - 10^7 M_sun for
+a Kroupa IMF) and their spectra are characterized by broad, extended Br-gamma
+emission, so we refer to them as emission-line clusters (ELCs) to distinguish
+them from older SSCs. The Brgamma lines of most ELCs have supersonic widths
+(60-110 km/s FWHM) and non-Gaussian wings whose velocities exceed the clusters'
+escape velocities. This high-velocity unbound gas is flowing out in winds that
+are powered by the clusters' massive O and W-R stars over the course of at
+least several crossing times. The large sizes of some ELCs relative to those of
+older SSCs may be due to expansion caused by these outflows; many of the ELCs
+may not survive as bound stellar systems, but rather dissipate rapidly into the
+field population. The observed tendency of older ELCs to be more compact than
+young ones is consistent with the preferential survival of the most
+concentrated clusters at a given age.",0706.3935v1
+2007-06-29,Reliable Final Computational Results from Faulty Quantum Computation,"In this paper we extend both standard fault tolerance theory and Kitaev's
+model for quantum computation, combining them so as to yield quantitative
+results that reveal the interplay between the two. Our analysis establishes a
+methodology that allows us to quantitatively determine design parameters for a
+quantum computer, the values of which ensure that an overall computation of
+interest yields a correct *final result* with some prescribed probability of
+success, as opposed to merely ensuring that the desired *final quantum state*
+is obtained. As a specific example of the practical application of our
+approach, we explicitly calculate the number of levels of error correction
+concatenation needed to achieve a correct final result for the overall
+computation with some prescribed success probability. Since our methodology
+allows one to determine parameters required in order to achieve the correct
+final result for the overall quantum computation, as opposed to merely ensuring
+that the desired final quantum state is produced, our method enables the
+determination of complete quantum computational resource requirements
+associated to the actual solution of practical problems.",0707.0008v1
+2007-08-24,Quantum Sensor Miniaturization,"The classical bound on image resolution defined by the Rayleigh limit can be
+beaten by exploiting the properties of quantum mechanical entanglement. If
+entangled photons are used as signal states, the best possible resolution is
+instead given by the Heisenberg limit, an improvement proportional to the
+number of entangled photons in the signal. In this paper we present a novel
+application of entanglement by showing that the resolution obtained by an
+imaging system utilizing separable photons can be achieved by an imaging system
+making use of entangled photons, but with the advantage of a smaller aperture,
+thus resulting in a smaller and lighter system. This can be especially valuable
+in satellite imaging where weight and size play a vital role.",0708.3403v1
+2007-09-02,A Universal Operator Theoretic Framework for Quantum Fault Tolerance,"In this paper we introduce a universal operator theoretic framework for
+quantum fault tolerance. This incorporates a top-down approach that implements
+a system-level criterion based on specification of the full system dynamics,
+applied at every level of error correction concatenation. This leads to more
+accurate determinations of error thresholds than could previously be obtained.
+This is demonstrated both formally and with an explicit numerical example. The
+basis for our approach is the Quantum Computer Condition (QCC), an inequality
+governing the evolution of a quantum computer. We show that all known coding
+schemes are actually special cases of the QCC. We demonstrate this by
+introducing a new, operator theoretic form of entanglement assisted quantum
+error correction, which incorporates as special cases all known error
+correcting protocols, and is itself a special case of the QCC.",0709.0128v3
+2007-10-25,Ordering in red abalone nacre,"Red abalone nacre is an intensely studied biomineral, and yet its formation
+mechanism remains poorly understood. Here we report quantitative measurements
+probing the degree of order of the aragonite tablets in nacre, and show that
+order develops over a distance of about 50 microns. These observations indicate
+that the orientational order of aragonite tablets in nacre is established
+gradually and dynamically, and we show that a model of controlled assembly
+based on suppression of the crystal growth rate along a specific direction,
+when growth is confined in a layered structure, yields a tablet pattern
+consistent with those revealed by detailed experimental measurements. This work
+provides strong evidence that the organism s control of crystal orientation in
+nacre occurs via regulation of crystal nucleation and growth as opposed to
+direct templation or heteroepitaxial growth on organic molecules on the organic
+matrix sheets.",0710.4573v1
+2007-11-01,Interaction effects in mixed-valent Kondo insulators,"We study theoretically the class of mixed-valent Kondo insulators, employing
+a recently developed local moment approach to heavy Fermion systems using the
+asymmetric periodic Anderson model (PAM). Novel features in spectra and
+transport, observable experimentally but lying outside the scope of the
+symmetric PAM or the Kondo lattice model, emerge naturally within the present
+theory. We argue in particular that a shoulder-like feature in the optical
+conductivity, that is distinct from the usual mid-infrared or direct gap peak
+and has been observed experimentally in mixed-valent compounds such as
+CeOs4Sb12 and YbAl3, is of intrinsic origin. Detailed comparison is made
+between the resultant theory and transport/optical experiments on the
+filled-skutterudite compound CeOs4Sb12, and good agreement is obtained.",0711.0121v1
+2008-01-31,Counting growth types of automorphisms of free groups,"Given an automorphism of a free group $F_n$, we consider the following
+invariants: $e$ is the number of exponential strata (an upper bound for the
+number of different exponential growth rates of conjugacy classes); $d$ is the
+maximal degree of polynomial growth of conjugacy classes; $R$ is the rank of
+the fixed subgroup. We determine precisely which triples $(e,d,R)$ may be
+realized by an automorphism of $F_n$. In particular, the inequality $e\le
+(3n-2)/4}$ (due to Levitt-Lustig) always holds. In an appendix, we show that
+any conjugacy class grows like a polynomial times an exponential under
+iteration of the automorphism.",0801.4844v2
+2008-04-29,Combining geometry and combinatorics: A unified approach to sparse signal recovery,"There are two main algorithmic approaches to sparse signal recovery:
+geometric and combinatorial. The geometric approach starts with a geometric
+constraint on the measurement matrix and then uses linear programming to decode
+information about the signal from its measurements. The combinatorial approach
+constructs the measurement matrix and a combinatorial decoding algorithm to
+match. We present a unified approach to these two classes of sparse signal
+recovery algorithms.
+  The unifying elements are the adjacency matrices of high-quality unbalanced
+expanders. We generalize the notion of Restricted Isometry Property (RIP),
+crucial to compressed sensing results for signal recovery, from the Euclidean
+norm to the l_p norm for p about 1, and then show that unbalanced expanders are
+essentially equivalent to RIP-p matrices.
+  From known deterministic constructions for such matrices, we obtain new
+deterministic measurement matrix constructions and algorithms for signal
+recovery which, compared to previous deterministic algorithms, are superior in
+either the number of measurements or in noise tolerance.",0804.4666v1
+2008-08-08,Heat conductivity from molecular chaos hypothesis in locally confined billiard systems,"We study the transport properties of a large class of locally confined
+Hamiltonian systems, in which neighboring particles interact through hard core
+elastic collisions. When these collisions become rare and the systems large, we
+derive a Boltzmann-like equation for the evolution of the probability
+densities. We solve this equation in the linear regime and compute the heat
+conductivity from a Green-Kubo formula. The validity of our approach is
+demonstated by comparing our predictions to the results of numerical
+simulations performed on a new class of high-dimensional defocusing chaotic
+billiards.",0808.1179v2
+2008-09-23,On the derivation of Fourier's law in stochastic energy exchange systems,"We present a detailed derivation of Fourier's law in a class of stochastic
+energy exchange systems that naturally characterize two-dimensional mechanical
+systems of locally confined particles in interaction. The stochastic systems
+consist of an array of energy variables which can be partially exchanged among
+nearest neighbours at variable rates. We provide two independent derivations of
+the thermal conductivity and prove this quantity is identical to the frequency
+of energy exchanges. The first derivation relies on the diffusion of the
+Helfand moment, which is determined solely by static averages. The second
+approach relies on a gradient expansion of the probability measure around a
+non-equilibrium stationary state. The linear part of the heat current is
+determined by local thermal equilibrium distributions which solve a
+Boltzmann-like equation. A numerical scheme is presented with computations of
+the conductivity along our two methods. The results are in excellent agreement
+with our theory.",0809.3967v2
+2008-10-19,Coding Theorems for Repeat Multiple Accumulate Codes,"In this paper the ensemble of codes formed by a serial concatenation of a
+repetition code with multiple accumulators connected through random
+interleavers is considered. Based on finite length weight enumerators for these
+codes, asymptotic expressions for the minimum distance and an arbitrary number
+of accumulators larger than one are derived using the uniform interleaver
+approach. In accordance with earlier results in the literature, it is first
+shown that the minimum distance of repeat-accumulate codes can grow, at best,
+sublinearly with block length. Then, for repeat-accumulate-accumulate codes and
+rates of 1/3 or less, it is proved that these codes exhibit asymptotically
+linear distance growth with block length, where the gap to the
+Gilbert-Varshamov bound can be made vanishingly small by increasing the number
+of accumulators beyond two. In order to address larger rates, random puncturing
+of a low-rate mother code is introduced. It is shown that in this case the
+resulting ensemble of repeat-accumulate-accumulate codes asymptotically
+achieves linear distance growth close to the Gilbert-Varshamov bound. This
+holds even for very high rate codes.",0810.3422v1
+2008-12-09,Statistical properties of time-reversible triangular maps of the square,"Time reversal symmetric triangular maps of the unit square are introduced
+with the property that the time evolution of one of their two variables is
+determined by a piecewise expanding map of the unit interval. We study their
+statistical properties and establish the conditions under which their
+equilibrium measures have a product structure, i.e. factorises in a symmetric
+form. When these conditions are not verified, the equilibrium measure does not
+have a product form and therefore provides additional information on the
+statistical properties of theses maps. This is the case of anti-symmetric cusp
+maps, which have an intermittent fixed point and yet have uniform invariant
+measures on the unit interval. We construct the invariant density of the
+corresponding two-dimensional triangular map and prove that it exhibits a
+singularity at the intermittent fixed point.",0812.1648v1
+2009-03-20,Fractality of the non-equilibrium stationary states of open volume-preserving systems: I. Tagged particle diffusion,"Deterministic diffusive systems such as the periodic Lorentz gas, multi-baker
+map, as well as spatially periodic systems of interacting particles, have
+non-equilibrium stationary states with fractal properties when put in contact
+with particle reservoirs at their boundaries. We study the macroscopic limits
+of these systems and establish a correspondence between the thermodynamics of
+the macroscopic diffusion process and the fractality of the stationary states
+that characterize the phase-space statistics. In particular the entropy
+production rate is recovered from first principles using a formalism due to
+Gaspard [J. Stat. Phys. 88, 1215 (1997)]. This article is the first of two; the
+second article considers the influence of a uniform external field on such
+systems.",0903.3476v1
+2009-03-20,Fractality of the non-equilibrium stationary states of open volume-preserving systems: II. Galton boards,"Galton boards are models of deterministic diffusion in a uniform external
+field, akin to driven periodic Lorentz gases, here considered in the absence of
+dissipation mechanism. Assuming a cylindrical geometry with axis along the
+direction of the external field, the two-dimensional board becomes a model for
+one-dimensional mass transport along the direction of the external field. This
+is a purely diffusive process which admits fractal non-equilibrium stationary
+states under flux boundary conditions. Analytical results are obtained for the
+statistics of multi-baker maps modeling such a non-uniform diffusion process. A
+correspondence is established between the local phase-space statistics and
+their macroscopic counter-parts. The fractality of the invariant state is shown
+to be responsible for the positiveness of the entropy production rate.",0903.3849v1
+2009-07-23,On Possible Variation in the Cosmological Baryon Fraction,"The fraction of matter that is in the form of baryons or dark matter could
+have spatial fluctuations in the form of baryon-dark matter isocurvature
+fluctuations. We use big bang nucleosynthesis calculations compared with
+observed light element abundances as well as galaxy cluster gas fractions to
+constrain cosmological variations in the baryon fraction. Light element
+abundances constrain spatial variations to be less than 26-27%, while a sample
+of ""relaxed"" galaxy clusters shows spatial variations in gas fractions less
+than 8%. Larger spatial variations could cause differential screening of the
+primary cosmic microwave background anisotropies, leading to asymmetries in the
+fluctuations and ease some tension with the halo-star 7Li abundance.
+Fluctuations within our allowed bounds can lead to ""B-mode"" CMB polarization
+anisotropies at a non-negligible level.",0907.3919v2
+2009-08-28,Chaos in cylindrical stadium billiards via a generic nonlinear mechanism,"We describe conditions under which higher-dimensional billiard models in
+bounded, convex regions are fully chaotic, generalizing the Bunimovich stadium
+to dimensions above two. An example is a three-dimensional stadium bounded by a
+cylinder and several planes; the combination of these elements may give rise to
+defocusing, allowing large chaotic regions in phase space. By studying families
+of marginally-stable periodic orbits that populate the residual part of phase
+space, we identify conditions under which a nonlinear instability mechanism
+arises in their vicinity. For particular geometries, this mechanism rather
+induces stable nonlinear oscillations, including in the form of
+whispering-gallery modes.",0908.4243v2
+2009-09-23,The Gilbert Arborescence Problem,"We investigate the problem of designing a minimum cost flow network
+interconnecting n sources and a single sink, each with known locations in a
+normed space and with associated flow demands. The network may contain any
+finite number of additional unprescribed nodes from the space; these are known
+as the Steiner points. For concave increasing cost functions, a minimum cost
+network of this sort has a tree topology, and hence can be called a Minimum
+Gilbert Arborescence (MGA). We characterise the local topological structure of
+Steiner points in MGAs, showing, in particular, that for a wide range of
+metrics, and for some typical real-world cost-functions, the degree of each
+Steiner point is 3.",0909.4270v2
+2010-08-12,Magnetization dynamics in the inertial regime: nutation predicted at short time scales,"The dynamical equation of the magnetization has been reconsidered with
+enlarging the phase space of the ferromagnetic degrees of freedom to the
+angular momentum. The generalized Landau-Lifshitz-Gilbert equation that
+includes inertial terms, and the corresponding Fokker-Planck equation, are then
+derived in the framework of mesoscopic non-equilibrium thermodynamics theory. A
+typical relaxation time $\tau$ is introduced describing the relaxation of the
+magnetization acceleration from the inertial regime towards the precession
+regime defined by a constant Larmor frequency. For time scales larger than
+$\tau$, the usual Gilbert equation is recovered. For time scales below $\tau$,
+nutation and related inertial effects are predicted. The inertial regime offers
+new opportunities for the implementation of ultrafast magnetization switching
+in magnetic devices.",1008.2177v1
+2010-11-03,Existence of vertical spin stiffness in Landau-Lifshitz-Gilbert equation in ferromagnetic semiconductors,"We calculate the magnetization torque due to the spin polarization of the
+itinerant electrons by deriving the kinetic spin Bloch equations based on the
+$s$-$d$ model. We find that the first-order gradient of the magnetization
+inhomogeneity gives rise to the current-induced torques, which are consistent
+to the previous works. At the second-order gradient, we find an effective
+magnetic field perpendicular to the spin stiffness filed. This field is
+proportional to the nonadiabatic parameter $\beta$. We show that this vertical
+spin stiffness term can significantly modify the domain-wall structure in
+ferromagnetic semiconductors and hence should be included in the
+Landau-Lifshitz-Gilbert equation in studying the magnetization dynamics.",1011.0871v1
+2011-01-05,The Fascinating World of Landau-Lifshitz-Gilbert Equation: An Overview,"The Landau-Lifshitz-Gilbert (LLG) equation is a fascinating nonlinear
+evolution equation both from mathematical and physical points of view. It is
+related to the dynamics of several important physical systems such as
+ferromagnets, vortex filaments, moving space curves, etc. and has intimate
+connections with many of the well known integrable soliton equations, including
+nonlinear Schr\""odinger and sine-Gordon equations. It can admit very many
+dynamical structures including spin waves, elliptic function waves, solitons,
+dromions, vortices, spatio-temporal patterns, chaos, etc. depending on the
+physical and spin dimensions and the nature of interactions. An exciting recent
+development is that the spin torque effect in nanoferromagnets is described by
+a generalization of the LLG equation which forms a basic dynamical equation in
+the field of spintronics. This article will briefly review these developments
+as a tribute to Robin Bullough who was a great admirer of the LLG equation.",1101.1005v1
+2011-02-05,Graph Theory,"This is a replacement paper. There are 6 chapters. The first two chapters are
+introductory. The third chapter is on extremal graph theory. The fourth chapter
+is about algebra in graph theory. The fifth chapter is focused on algorithms.
+The third section of the fifth chapter deals with computable time. The sixth
+chapter has sections on probability and enumeration.",1102.1087v11
+2011-04-28,The High-Redshift Neutral Hydrogen Signature of an Anisotropic Matter Power Spectrum,"An anisotropic power spectrum will have a clear signature in the 21cm
+radiation from high-redshift hydrogen. We calculate the expected power spectrum
+of the intensity fluctuations in neutral hydrogen from before the epoch of
+reionization, and predict the accuracy to which future experiments could
+constrain a quadrupole anisotropy in the power spectrum. We find that the
+Square Kilometer Array will have marginal detection abilities for this signal
+at z~17 if the process of reionization has not yet started; reionization could
+enhance the detectability substantially. Pushing to higher redshifts and higher
+sensitivity will allow highly precise (percent level) measurements of
+anisotropy.",1104.5403v3
+2011-06-30,A generalisation of the Gilbert-Varshamov bound and its asymptotic evaluation,"The Gilbert-Varshamov (GV) lower bound on the maximum cardinality of a q-ary
+code of length n with minimum Hamming distance at least d can be obtained by
+application of Turan's theorem to the graph with vertex set {0,1,..,q-1}^n in
+which two vertices are joined if and only if their Hamming distance is at least
+d. We generalize the GV bound by applying Turan's theorem to the graph with
+vertex set C^n, where C is a q-ary code of length m and two vertices are joined
+if and only if their Hamming distance at least d. We asymptotically evaluate
+the resulting bound for n-> \infty and d \delta mn for fixed \delta > 0, and
+derive conditions on the distance distribution of C that are necessary and
+sufficient for the asymptotic generalized bound to beat the asymptotic GV
+bound. By invoking the Delsarte inequalities, we conclude that no improvement
+on the asymptotic GV bound is obtained. By using a sharpening of Turan's
+theorem due to Caro and Wei, we improve on our bound. It is undecided if there
+exists a code C for which the improved bound can beat the asymptotic GV bound.",1106.6206v1
+2011-07-17,Probabilistic Methods on Erdos Problems,"The paper reviews and tries to describe the reference set method, which is a
+method of combinatorial optimization that gives upper bounds on parameters.",1107.3279v17
+2011-09-12,Externally-driven transmission and collisions of domain walls in ferromagnetic wires,"Analytical multi-domain solutions to the dynamical (Landau-Lifshitz-Gilbert)
+equation of a one-dimensional ferromagnet including an external magnetic field
+and spin-polarized electric current are found using the Hirota bilinearization
+method. A standard approach to solve the Landau-Lifshitz equation (without the
+Gilbert term) is modified in order to treat the dissipative dynamics. I
+establish the relations between the spin interaction parameters (the constants
+of exchange, anisotropy, dissipation, external-field intensity, and
+electric-current intensity) and the domain-wall parameters (width and velocity)
+and compare them to the results of the Walker approximation and micromagnetic
+simulations. The domain-wall motion driven by a longitudinal external field is
+analyzed with especial relevance to the field-induced collision of two domain
+walls. I determine the result of such a collision (which is found to be the
+elastic one) on the domain-wall parameters below and above the Walker breakdown
+(in weak- and strong-field regimes). Single-domain-wall dynamics in the
+presence of an external transverse field is studied with relevance to the
+challenge of increasing the domain-wall velocity below the breakdown.",1109.2465v1
+2011-10-19,Current-induced switching in transport through anisotropic magnetic molecules,"Anisotropic single-molecule magnets may be thought of as molecular switches,
+with possible applications to molecular spintronics. In this paper, we consider
+current-induced switching in single-molecule junctions containing an
+anisotropic magnetic molecule. We assume that the carriers interact with the
+magnetic molecule through the exchange interaction and focus on the regime of
+high currents in which the molecular spin dynamics is slow compared to the time
+which the electrons spend on the molecule. In this limit, the molecular spin
+obeys a non-equilibrium Langevin equation which takes the form of a generalized
+Landau-Lifshitz-Gilbert equation and which we derive microscopically by means
+of a non-equilibrium Born-Oppenheimer approximation. We exploit this Langevin
+equation to identify the relevant switching mechanisms and to derive the
+current-induced switching rates. As a byproduct, we also derive S-matrix
+expressions for the various torques entering into the Landau-Lifshitz-Gilbert
+equation which generalize previous expressions in the literature to
+non-equilibrium situations.",1110.4270v2
+2011-10-27,"George Augustus Linhart - as a ""widely unknown"" thermodynamicist","The name of George Augustus Linhart is in fact ""widely unknown"". In effect,
+he was a Viennese-born USA-American physicist-chemist, partially associated
+with the Gilbert Newton Lewis' school of thermodynamics at the University of
+California in Berkeley. As a lone small boy, he had arrived (from Austria via
+Hamburg) at New York in 1896, but was officially USA-naturalized only in 1912.
+He was able to pick up English in the streets of New York and Philadelphia,
+when occasionally working as a waiter and/or as a tailor - just to somehow
+survive. But, nonetheless, he could successfully graduate a high school in
+about one year - and then went to the universities for his further education.
+After obtaining his BS from the University of Pennsylvania, he could manage
+getting both MA and then PhD from the Yale University, Kent Chemical
+Laboratory. George Augustus Linhart was afterwards definitely able to
+successfully work out the true foundations of thermodynamics and could thus
+outdistance many famous thermodynamicists of his time and even the later ones.
+Linhart's view of the Second Law of Thermodynamics was and is extremely
+fruitful. The interconnection of Linhart's ideas with those of Gilbert Newton
+Lewis, as well as with the modern standpoints are discussed here in detail.",1110.6352v1
+2012-03-29,Power Allocation over Two Identical Gilbert-Elliott Channels,"We study the problem of power allocation over two identical Gilbert-Elliot
+communication channels. Our goal is to maximize the expected discounted number
+of bits transmitted over an infinite time horizon. This is achieved by choosing
+among three possible strategies: (1) betting on channel 1 by allocating all the
+power to this channel, which results in high data rate if channel 1 happens to
+be in good state, and zero bits transmitted if channel 1 is in bad state (even
+if channel 2 is in good state) (2) betting on channel 2 by allocating all the
+power to the second channel, and (3) a balanced strategy whereby each channel
+is allocated half the total power, with the effect that each channel can
+transmit a low data rate if it is in good state. We assume that each channel's
+state is only revealed upon transmission of data on that channel. We model this
+problem as a partially observable Markov decision processes (MDP), and derive
+key threshold properties of the optimal policy. Further, we show that by
+formulating and solving a relevant linear program the thresholds can be
+determined numerically when system parameters are known.",1203.6630v2
+2012-04-11,A short note on spin pumping theory with Landau-Lifshitz-Gilbert equation under quantum fluctuation; necessity for quantization of localized spin,"We would like to point out the blind spots of the approach combining the spin
+pumping theory proposed by Tserkovnyak et al. with the Landau-Lifshitz-Gilbert
+equation; this method has been widely used for interpreting vast experimental
+results. The essence of the spin pumping effect is the quantum fluctuation.
+Thus, localized spin degrees of freedom should be quantized, i.e. be treated as
+magnons not as classical variables. Consequently, the precessing ferromagnet
+can be regarded as a magnon battery. This point of view will be useful for
+further progress of spintronics.",1204.2339v1
+2012-05-22,Signature of Phase Transitions in the Disordered Quantum Spin Hall State From the Entanglement Spectrum,"Of the available classes of insulators which have been shown to contain
+topologically non-trivial properties one of the most important is class AII,
+which contains systems that possess time-reversal symmetry $T$ with $T^2=-1.$
+This class has been the subject of significant attention as it encompasses
+non-trivial Z$_2$ topological insulators such as the quantum spin Hall (QSH)
+state and the 3D strong topological insulator. One of the defining properties
+of this system is the robustness of the state under the addition of disorder
+that preserves $T.$ In this letter, we explore the phase diagram of the
+disordered QSH state as a function of disorder strength and chemical potential
+by examining the entanglement spectrum for disordered class AII symplectic
+systems. As for the case of the $T$ breaking Chern insulator we show that there
+is a correspondence between the level-spacing statistics of the Hamiltonian and
+that of the level spacing statistics of the entanglement spectrum. We observe a
+feature in the statistics of the entanglement spectrum that aids the
+identification of delocalized states and consequently critical energies across
+which phase transitions occur.",1205.5071v1
+2012-07-03,The unusual smoothness of the extragalactic unresolved radio background,"If the radio background is coming from cosmological sources, there should be
+some amount of clustering due to the large scale structure in the universe.
+Simple models for the expected clustering combined with the recent measurement
+by ARCADE-2 of the mean extragalactic temperature lead to predicted clustering
+levels that are substantially above upper limits from searches for anisotropy
+on arcminute scales using ATCA and the VLA. The rms temperature variations in
+the cosmic radio background appear to be more than a factor of 10 smaller (in
+temperature) than the fluctuations in the cosmic infrared background. It is
+therefore extremely unlikely that this background comes from galaxies, galaxy
+clusters, or any sources that trace dark matter halos at z<5, unless typical
+sources are smooth on arcminute scales, requiring typical sizes of several Mpc.",1207.0856v1
+2012-10-12,Optimal Power Allocation Policy over Two Identical Gilbert-Elliott Channels,"We study the fundamental problem of optimal power allocation over two
+identical Gilbert-Elliott (Binary Markov) communication channels. Our goal is
+to maximize the expected discounted number of bits transmitted over an infinite
+time span by judiciously choosing one of the four actions for each time slot:
+1) allocating power equally to both channels, 2) allocating all the power to
+channel 1, 3) allocating all the power to channel 2, and 4) allocating no power
+to any of the channels. As the channel state is unknown when power allocation
+decision is made, we model this problem as a partially observable Markov
+decision process(POMDP), and derive the optimal policy which gives the optimal
+action to take under different possible channel states. Two different
+structures of the optimal policy are derived analytically and verified by
+linear programming simulation. We also illustrate how to construct the optimal
+policy by the combination of threshold calculation and linear programming
+simulation once system parameters are known.",1210.3609v1
+2013-03-16,A convergent linear finite element scheme for the Maxwell-Landau-Lifshitz-Gilbert equation,"We consider a lowest-order finite element discretization of the nonlinear
+system of Maxwell's and Landau-Lifshitz-Gilbert equations (MLLG). Two
+algorithms are proposed to numerically solve this problem, both of which only
+require the solution of at most two linear systems per timestep. One of the
+algorithms is fully decoupled in the sense that each timestep consists of the
+sequential computation of the magnetization and afterwards the magnetic and
+electric field. Under some mild assumptions on the effective field, we show
+that both algorithms converge towards weak solutions of the MLLG system.
+Numerical experiments for a micromagnetic benchmark problem demonstrate the
+performance of the proposed algorithms.",1303.4009v1
+2013-03-17,On the Landau-Lifshitz-Gilbert equation with magnetostriction,"To describe and simulate dynamic micromagnetic phenomena, we consider a
+coupled system of the nonlinear Landau-Lifshitz-Gilbert equation and the
+conservation of momentum equation. This coupling allows to include
+magnetostrictive effects into the simulations. Existence of weak solutions has
+recently been shown in [Carbout et al. 2011]. In our contribution, we give an
+alternate proof which additionally provides an effective numerical integrator.
+The latter is based on lowest-order finite elements in space and a
+linear-implicit Euler time-stepping. Despite the nonlinearity, only two linear
+systems have to be solved per timestep, and the integrator fully decouples both
+equations. Finally, we prove unconditional convergence---at least of a
+subsequence---towards, and hence existence of, a weak solution of the coupled
+system, as timestep size and spatial mesh-size tend to zero. Numerical
+experiments conclude the work and shed new light on the existence of blow-up in
+micromagnetic simulations.",1303.4060v2
+2013-03-27,Optimal Power Allocation over Multiple Identical Gilbert-Elliott Channels,"We study the fundamental problem of power allocation over multiple
+Gilbert-Elliott communication channels. In a communication system with time
+varying channel qualities, it is important to allocate the limited transmission
+power to channels that will be in good state. However, it is very challenging
+to do so because channel states are usually unknown when the power allocation
+decision is made. In this paper, we derive an optimal power allocation policy
+that can maximize the expected discounted number of bits transmitted over an
+infinite time span by allocating the transmission power only to those channels
+that are believed to be good in the coming time slot. We use the concept belief
+to represent the probability that a channel will be good and derive an optimal
+power allocation policy that establishes a mapping from the channel belief to
+an allocation decision.
+  Specifically, we first model this problem as a partially observable Markov
+decision processes (POMDP), and analytically investigate the structure of the
+optimal policy. Then a simple threshold-based policy is derived for a
+three-channel communication system. By formulating and solving a linear
+programming formulation of this power allocation problem, we further verified
+the derived structure of the optimal policy.",1303.6771v1
+2013-04-29,Generalized Baumslag-Solitar groups: rank and finite index subgroups,"A generalized Baumslag-Solitar (GBS) group is a finitely generated group
+acting on a tree with infinite cyclic edge and vertex stabilizers. We show how
+to determine effectively the rank (minimal cardinality of a generating set) of
+a GBS group; as a consequence, one can compute the rank of the mapping torus of
+a finite order outer automorphism of a free group $F_n$. We also show that the
+rank of a finite index subgroup of a GBS group G cannot be smaller than the
+rank of G. We determine which GBS groups are large (some finite index subgroup
+maps onto $F_2$), and we solve the commensurability problem (deciding whether
+two groups have isomorphic finite index subgroups) in a particular family of
+GBS groups.",1304.7582v2
+2013-06-02,On the Riemannian Penrose inequality with charge and the cosmic censorship conjecture,"We note an area-charge inequality orignially due to Gibbons: if the outermost
+horizon $S$ in an asymptotically flat electrovacuum initial data set is
+connected then $|q|\leq r$, where $q$ is the total charge and $r=\sqrt{A/4\pi}$
+is the area radius of $S$. A consequence of this inequality is that for
+connected black holes the following lower bound on the area holds: $r\geq
+m-\sqrt{m^2-q^2}$. In conjunction with the upper bound $r\leq m +
+\sqrt{m^2-q^2}$ which is expected to hold always, this implies the natural
+generalization of the Riemannian Penrose inequality: $m\geq 1/2(r+q^2/r)$.",1306.0206v3
+2013-08-19,A finite element approximation for the stochastic Landau-Lifshitz-Gilbert equation,"The stochastic Landau--Lifshitz--Gilbert (LLG) equation describes the
+behaviour of the magnetization under the influence of the effective field
+consisting of random fluctuations. We first reformulate the equation into an
+equation the unknown of which is differentiable with respect to the time
+variable. We then propose a convergent $\theta$-linear scheme for the numerical
+solution of the reformulated equation. As a consequence, we show the existence
+of weak martingale solutions to the stochastic LLG equation. A salient feature
+of this scheme is that it does not involve a nonlinear system, and that no
+condition on time and space steps is required when $\theta\in(\frac{1}{2},1]$.
+Numerical results are presented to show the applicability of the method.",1308.3912v2
+2014-01-14,Constructions of Pure Asymmetric Quantum Alternant Codes Based on Subclasses of Alternant Codes,"In this paper, we construct asymmetric quantum error-correcting codes(AQCs)
+based on subclasses of Alternant codes. Firstly, We propose a new subclass of
+Alternant codes which can attain the classical Gilbert-Varshamov bound to
+construct AQCs. It is shown that when $d_x=2$, $Z$-parts of the AQCs can attain
+the classical Gilbert-Varshamov bound. Then we construct AQCs based on a famous
+subclass of Alternant codes called Goppa codes. As an illustrative example, we
+get three $[[55,6,19/4]],[[55,10,19/3]],[[55,15,19/2]]$ AQCs from the well
+known $[55,16,19]$ binary Goppa code. At last, we get asymptotically good
+binary expansions of asymmetric quantum GRS codes, which are quantum
+generalizations of Retter's classical results. All the AQCs constructed in this
+paper are pure.",1401.3215v2
+2014-03-19,Numerical integration of the stochastic Landau-Lifshitz-Gilbert equation in generic time-discretisation schemes,"We introduce a numerical method to integrate the stochastic
+Landau-Lifshitz-Gilbert equation in spherical coordinates for generic
+discretization schemes. This method conserves the magnetization modulus and
+ensures the approach to equilibrium under the expected conditions. We test the
+algorithm on a benchmark problem: the dynamics of a uniformly magnetized
+ellipsoid. We investigate the influence of various parameters, and in
+particular, we analyze the efficiency of the numerical integration, in terms of
+the number of steps needed to reach a chosen long time with a given accuracy.",1403.4822v2
+2014-05-05,Measuring logarithmic corrections to normal diffusion in infinite-horizon billiards,"We perform numerical measurements of the moments of the position of a tracer
+particle in a two-dimensional periodic billiard model (Lorentz gas) with
+infinite corridors. This model is known to exhibit a weak form of
+super-diffusion, in the sense that there is a logarithmic correction to the
+linear growth in time of the mean-squared displacement. We show numerically
+that this expected asymptotic behavior is easily overwhelmed by the subleading
+linear growth throughout the time-range accessible to numerical simulations. We
+compare our simulations to the known analytical results for the variance of the
+anomalously-rescaled limiting normal distributions.",1405.0975v2
+2014-05-12,Efficient Energy-minimization in Finite-Difference Micromagnetics: Speeding up Hysteresis Computations,"We implement an efficient energy-minimization algorithm for finite-difference
+micromagnetics that proofs especially useful for the computation of hysteresis
+loops. Compared to results obtained by time integration of the
+Landau-Lifshitz-Gilbert equation, a speedup of up to two orders of magnitude is
+gained. The method is implemented in a finite-difference code running on CPUs
+as well as GPUs. This setup enables us to compute accurate hysteresis loops of
+large systems with a reasonable computational effort. As a benchmark we solve
+the {\mu}Mag Standard Problem #1 with a high spatial resolution and compare the
+results to the solution of the Landau-Lifshitz-Gilbert equation in terms of
+accuracy and computing time.",1405.2728v3
+2014-07-26,Magnetization reversal condition for a nanomagnet within a rotating magnetic field,"The reversal condition of magnetization in a nanomagnet under the effect of
+rotating magnetic field generated by a microwave is theoretically studied based
+on the Landau-Lifshitz-Gilbert equation. In a rotating frame, the microwave
+produces a dc magnetic field pointing in the reversed direction, which
+energetically stabilizes the reversed state. We find that the microwave
+simultaneously produces a torque preventing the reversal. It is pointed out
+that this torque leads to a jump in the reversal field with respect to the
+frequency. We derive the equations determining the reversal fields in both the
+low- and high-frequency regions from the energy balance equation. The
+validities of the formulas are confirmed by a comparison with the numerical
+simulation of the Landau-Lifshitz-Gilbert equation.",1407.7095v1
+2014-09-17,Aharonov-Bohm Oscillations in a Quasi-Ballistic 3D Topological Insulator Nanowire,"In three-dimensional topological insulators (3D TI) nanowires, transport
+occurs via gapless surface states where the spin is fixed perpendicular to the
+momentum[1-6]. Carriers encircling the surface thus acquire a \pi Berry phase,
+which is predicted to open up a gap in the lowest-energy 1D surface subband.
+Inserting a magnetic flux ({\Phi}) of h/2e through the nanowire should cancel
+the Berry phase and restore the gapless 1D mode[7-8]. However, this signature
+has been missing in transport experiments reported to date[9-11]. Here, we
+report measurements of mechanically-exfoliated 3D TI nanowires which exhibit
+Aharonov-Bohm oscillations consistent with topological surface transport. The
+use of low-doped, quasi-ballistic devices allows us to observe a minimum
+conductance at {\Phi} = 0 and a maximum conductance reaching e^2/h at {\Phi} =
+h/2e near the lowest subband (i.e. the Dirac point), as well as the carrier
+density dependence of the transport.",1409.5095v1
+2014-10-13,[$α$/Fe] Abundances of Four Outer M 31 Halo Stars,"We present alpha element to iron abundance ratios, [$\alpha$/Fe], for four
+stars in the outer stellar halo of the Andromeda Galaxy (M 31). The stars were
+identified as high-likelihood field halo stars by Gilbert et al. (2012) and lie
+at projected distances between 70 and 140 kpc from M 31's center. These are the
+first alpha abundances measured for a halo star in a galaxy beyond the Milky
+Way. The stars range in metallicity between [Fe/H]= -2.2 and [Fe/H]= -1.4. The
+sample's average [$\alpha$/Fe] ratio is +0.20+/-0.20. The best-fit average
+value is elevated above solar which is consistent with rapid chemical
+enrichment from Type II supernovae. The mean [$\alpha$/Fe] ratio of our M31
+outer halo sample agrees (within the uncertainties) with that of Milky Way
+inner/outer halo stars that have a comparable range of [Fe/H].",1410.3475v1
+2014-11-05,Kalman Filtering over Gilbert-Elliott Channels: Stability Conditions and the Critical Curve,"This paper investigates the stability of Kalman filtering over
+Gilbert-Elliott channels where random packet drop follows a time-homogeneous
+two-state Markov chain whose state transition is determined by a pair of
+failure and recovery rates. First of all, we establish a relaxed condition
+guaranteeing peak-covariance stability described by an inequality in terms of
+the spectral radius of the system matrix and transition probabilities of the
+Markov chain. We further show that that condition can be interpreted using a
+linear matrix inequality feasibility problem. Next, we prove that the
+peak-covariance stability implies mean-square stability, if the system matrix
+has no defective eigenvalues on the unit circle. This connection between the
+two stability notions holds for any random packet drop process. We prove that
+there exists a critical curve in the failure-recovery rate plane, below which
+the Kalman filter is mean-square stable and no longer mean-square stable above,
+via a coupling method in stochastic processes. Finally, a lower bound for this
+critical failure rate is obtained making use of the relationship we establish
+between the two stability criteria, based on an approximate relaxation of the
+system matrix.",1411.1217v1
+2015-03-02,An Anisotropic Landau-Lifschitz-Gilbert model of dissipation in qubits,"We derive a microscopic model for dissipative dynamics in a system of
+mutually interacting qubits coupled to a thermal bath that generalises the
+dissipative model of Landau-Lifschitz-Gilbert to the case of anisotropic bath
+couplings. We show that the dissipation acts to bias the quantum trajectories
+towards a reduced phase space. This model applies to a system of
+superconducting flux qubits whose coupling to the environment is necessarily
+anisotropic. We study the model in the context of the D-Wave computing device
+and show that the form of environmental coupling in this case produces dynamics
+that are closely related to several models proposed on phenomenological
+grounds.",1503.00651v2
+2015-03-25,Optimising the neutron environment of Radiation Portal Monitors: a computational optimisation study,"Efficient and reliable detection of radiological or nuclear threats is a
+crucial part of national and international efforts to prevent terrorist
+activities. Radiation Portal Monitors (RPMs), which are deployed worldwide, are
+intended to interdict smuggled fissile material by detecting emissions of
+neutrons and gamma rays. However, considering the range and variety of threat
+sources, vehicular and shielding scenarios, and that only a small signature is
+present, it is important that the design of the RPMs allows these signatures to
+be accurately differentiated from the environmental background. Using
+Monte-Carlo neutron-transport simulations of a model helium-3 detector system
+we have conducted a parameter study to identify the optimum combination of
+detector shielding and collimation that maximises the sensitivity of RPMs.
+These structures, which could be simply and cost-effectively added to existing
+RPMs, can improve the detector response by more than a factor of two relative
+to an unmodified, bare design. Furthermore, optimisation of the air gap
+surrounding the helium tubes also improves detector efficiency.",1503.07346v1
+2015-06-29,Energy spectra of primary knock-on atoms under neutron irradiation,"Materials subjected to neutron irradiation will suffer from a build-up of
+damage caused by the displacement cascades initiated by nuclear reactions.
+Previously, the main ""measure"" of this damage accumulation has been through the
+displacements per atom (dpa) index. There are known limitations associated with
+the dpa quantity and its domain of application and therefore this paper
+describes a more rigorous methodology to calculate the primary atomic recoil
+events (often called the primary knock-on atoms or PKAs) that lead to cascade
+damage events as a function of energy and recoiling species for any simulated
+or measured neutron irradiation scenario. Via examples of fusion relevant
+materials, it is shown that the PKA spectra can be complex, involving many
+different recoiling species, potentially differing in both proton and neutron
+number from the original target nuclei, including high energy recoils of light
+emitted particles such as alpha-particles and protons. The variations in PKA
+spectra as a function of time, neutron field, and material are explored.
+Example PKA spectra are applied to radiation damage quantification using the
+binary collision approximation and stochastic cluster dynamics, and the results
+from these different approaches are discussed and compared.",1506.08554v1
+2015-08-25,Direct Visualization of Memory Effects in Artificial Spin Ice,"We experimentally demonstrate that arrays of interacting nanoscale
+ferromagnetic islands, known as artificial spin ice, develop reproducible
+microstates upon cycling an applied magnetic field. The onset of this memory
+effect is determined by the strength of the applied field relative to the array
+coercivity. Specifically, when the applied field strength is almost exactly
+equal to the array coercivity, several training cycles are required before the
+array achieves a nearly completely repeatable microstate, whereas when the
+applied field strength is stronger or weaker than the array coercivity, a
+repeatable microstate is achieved after the first minor loop. We show through
+experiment and simulation that this memory exhibited by artificial spin ice is
+due to a ratchet effect on interacting, magnetically-charged defects in the
+island moment configuration and to the complexity of the network of strings of
+reversed moments that forms during magnetization reversal.",1508.06330v1
+2015-10-21,On the limiting Markov process of energy exchanges in a rarely interacting ball-piston gas,"We analyse the process of energy exchanges generated by the elastic
+collisions between a point-particle, confined to a two-dimensional cell with
+convex boundaries, and a `piston', i.e. a line-segment, which moves back and
+forth along a one-dimensional interval partially intersecting the cell. This
+model can be considered as the elementary building block of a spatially
+extended high-dimensional billiard modeling heat transport in a class of hybrid
+materials exhibiting the kinetics of gases and spatial structure of solids.
+Using heuristic arguments and numerical analysis, we argue that, in a regime of
+rare interactions, the billiard process converges to a Markov jump process for
+the energy exchanges and obtain the expression of its generator.",1510.06408v2
+2015-10-29,Deligne--Langlands gamma factors in families,"Let F be a p-adic field, W_F its absolute Weil group, and let k be an
+algebraically closed field of prime characteristic l different from p. Attached
+to any l-adic representation of W_F are local epsilon- and L-factors. There are
+natural notions of families of l-adic representations of W_F, such as the
+theory of Galois deformations or, more generally, families over arbitrary
+Noetherian W(k)-algebras. However, the epsilon and L-factors do not interpolate
+well in such families. In this paper it is shown that the gamma factor, which
+is the product of the epsilon factor with a ratio of L-factors, interpolates
+over such families.",1510.08743v3
+2015-11-01,Verification of commercial motor performance for WEAVE at the William Herschel Telescope,"WEAVE is a 1000-fiber multi-object spectroscopic facility for the 4.2~m
+William Herschel Telescope. It will feature a double-headed pick-and-place
+fiber positioning robot comprising commercially available robotic axes. This
+paper presents results on the performance of these axes, obtained by testing a
+prototype system in the laboratory. Positioning accuracy is found to be better
+than the manufacturer's published values for the tested cases, indicating that
+the requirement for a maximum positioning error of 8.0~microns is achievable.
+Field reconfiguration times well within the planned 60 minute observation
+window are shown to be likely when individual axis movements are combined in an
+efficient way.",1511.00202v1
+2015-11-02,Learning from history: Adaptive calibration of 'tilting spine' fiber positioners,"This paper discusses a new approach for determining the calibration
+parameters of independently-actuated optical fibers in multi-object
+astronomical fiber positioning systems. This work comes from the development of
+a new type of piezoelectric motor intended to enhance the 'tilting spine' fiber
+positioning technology originally created by the Australian Astronomical
+Observatory. Testing has shown that the motor's performance can vary depending
+on the fiber's location within its accessible field, meaning that an individual
+fiber is difficult calibrate with a one-time routine. Better performance has
+resulted from constantly updating calibration parameters based on the observed
+movements of the fiber during normal closed-loop positioning. Over time,
+location-specific historical data is amassed that can be used to better predict
+the results of a future fiber movement. This is similar to a technique
+previously proposed by the Australian Astronomical Observatory, but with the
+addition of location-specific learning. Results from a prototype system are
+presented, showing a significant reduction in overall positioning error when
+using this new approach.",1511.00737v1
+2016-06-23,Echidna Mark II: one giant leap for 'tilting spine' fibre positioning technology,"The Australian Astronomical Observatory's 'tilting spine' fibre positioning
+technology has been redeveloped to provide superior performance in a smaller
+package. The new design offers demonstrated closed-loop positioning errors of
+2.8 {\mu}m RMS in only five moves (~10 s excluding metrology overheads) and an
+improved capacity for open-loop tracking during observations. Tilt-induced
+throughput losses have been halved by lengthening spines while maintaining
+excellent accuracy. New low-voltage multilayer piezo actuator technology has
+reduced a spine's peak drive amplitude from ~150 V to <10 V, simplifying the
+control electronics design, reducing the system's overall size, and improving
+modularity. Every spine is now a truly independent unit with a dedicated drive
+circuit and no restrictions on the timing or direction of fibre motion.",1606.07305v1
+2016-08-15,Inverse subsemigroups of finite index in finitely generated inverse semigroups,"The index of a subgroup of a group counts the number of cosets of that
+subgroup. A subgroup of finite index often shares structural properties with
+the group, and the existence of a subgroup of finite index with some particular
+property can therefore imply useful structural information for the overgroup. A
+developed theory of cosets in inverse semigroups exists, originally due to
+Schein: it is defined only for closed inverse subsemigroups, and the structural
+correspondences between an inverse semigroup and a closed inverse subsemigroup
+of finite index are weaker than in the group case. Nevertheless, many aspects
+of this theory are of interest, and some of them are addressed in this paper.
+We study the basic theory of cosets in inverse semigroups, including an index
+formula for chains of subgroups and an analogue of M. Hall's Theorem on
+counting subgroups of finite index in finitely generated groups. We then look
+in detail at the connection between the following properties of a closed
+inverse submonoid of an inverse monoid: having finite index; being a
+recognisable subset; being a rational subset; being finitely generated (as a
+closed inverse submonoid). A remarkable result of Margolis and Meakin shows
+that these properties are equivalent for closed inverse submonoids of free
+inverse monoids.",1608.04254v1
+2016-10-03,Magnetic microscopy and simulation of strain-mediated control of magnetization in Ni/PMN-PT nanostructures,"Strain-mediated thin film multiferroics comprising
+piezoelectric/ferromagnetic heterostructures enable the electrical manipulation
+of magnetization with much greater efficiency than other methods; however, the
+investigation of nanostructures fabricated from these materials is limited.
+Here we characterize ferromagnetic Ni nanostructures grown on a ferroelectric
+PMN-PT substrate using scanning electron microscopy with polarization analysis
+(SEMPA) and micromagnetic simulations. The magnetization of the Ni
+nanostructures can be controlled with a combination of sample geometry and
+applied electric field, which strains the ferroelectric substrate and changes
+the magnetization via magnetoelastic coupling. We evaluate two types of
+simulations of ferromagnetic nanostructures on strained ferroelectric
+substrates: conventional micromagnetic simulations including a simple uniaxial
+strain, and coupled micromagnetic-elastodynamic simulations. Both simulations
+qualitatively capture the response of the magnetization changes produced by the
+applied strain, with the coupled solution providing more accurate
+representation.",1610.00746v1
+2016-10-17,Formalising Real Numbers in Homotopy Type Theory,"Cauchy reals can be defined as a quotient of Cauchy sequences of rationals.
+The limit of a Cauchy sequence of Cauchy reals is defined through lifting it to
+a sequence of Cauchy sequences of rationals. This lifting requires the axiom of
+countable choice or excluded middle, neither of which is available in homotopy
+type theory. To address this, the Univalent Foundations Program uses a higher
+inductive-inductive type to define the Cauchy reals as the free Cauchy complete
+metric space generated by the rationals. We generalize this construction to
+define the free Cauchy complete metric space generated by an arbitrary metric
+space. This forms a monad in the category of metric spaces with Lipschitz
+functions. When applied to the rationals it defines the Cauchy reals. Finally,
+we can use Altenkirch and Danielson (2016)'s partiality monad to define a
+semi-decision procedure comparing a real number and a rational number.
+  The entire construction has been formalized in the Coq proof assistant. It is
+available at https://github.com/SkySkimmer/HoTTClasses/tree/CPP2017 .",1610.05072v2
+2016-11-04,The flow and evolution of ice-sucrose crystal mushes,"We study the rheology of suspensions of ice crystals at moderate to high
+volume fractions in a sucrose solution in which they are partially soluble; a
+model system for a wide class of crystal mushes or slurries. Under step changes
+in shear rate, the viscosity changes to a new `relaxed' value over several
+minutes, in a manner well fitted by a single exponential. The behavior of the
+relaxed viscosity is power-law shear thinning with shear rate, with an exponent
+of $-1.76 \pm 0.25$, so that shear stress falls with increasing shear rate. On
+longer timescales, the crystals ripen (leading to a falling viscosity) so that
+the mean radius increases with time to the power $0.14 \pm 0.07$. We speculate
+that this unusually small exponent is due to the interaction of classical
+ripening dynamics with abrasion or breakup under flow. We compare the
+rheological behavior to mechanistic models based on flow-induced aggregation
+and breakup of crystal clusters, finding that the exponents can be predicted
+from liquid phase sintering and breakup by brittle fracture.",1611.01365v1
+2016-11-08,Convergence of an implicit-explicit midpoint scheme for computational micromagnetics,"Based on lowest-order finite elements in space, we consider the numerical
+integration of the Landau-Lifschitz-Gilbert equation (LLG). The dynamics of LLG
+is driven by the so-called effective field which usually consists of the
+exchange field, the external field, and lower-order contributions such as the
+stray field. The latter requires the solution of an additional partial
+differential equation in full space. Following Bartels and Prohl (2006)
+(Convergence of an implicit finite element method for the
+Landau-Lifschitz-Gilbert equation. SIAM J. Numer. Anal. 44), we employ the
+implicit midpoint rule to treat the exchange field. However, in order to treat
+the lower-order terms effectively, we combine the midpoint rule with an
+explicit Adams-Bashforth scheme. The resulting integrator is formally of
+second-order in time, and we prove unconditional convergence towards a weak
+solution of LLG. Numerical experiments underpin the theoretical findings.",1611.02465v2
+2016-11-17,Dynamical contribution to the heat conductivity in stochastic energy exchanges of locally confined gases,"We present a systematic computation of the heat conductivity of the Markov
+jump process modeling the energy exchanges in an array of locally confined hard
+spheres at the conduction threshold. Based on a variational formula [Sasada M.
+2016, {\it Thermal conductivity for stochastic energy exchange models},
+arXiv:1611.08866], explicit upper bounds on the conductivity are derived, which
+exhibit a rapid power-law convergence towards an asymptotic value. We thereby
+conclude that the ratio of the heat conductivity to the energy exchange
+frequency deviates from its static contribution by a small negative correction,
+its dynamic contribution, evaluated to be $-0.000\,373$ in dimensionless units.
+This prediction is corroborated by kinetic Monte Carlo simulations which were
+substantially improved compared to earlier results.",1611.05809v3
+2016-11-27,Thermal conductivity for stochastic energy exchange models,"We consider a class of stochastic models for energy transport and study
+relations between the thermal conductivity and some static observables, such as
+the static conductivity, which is defined as the contribution of static
+correlations in Green-Kubo formula. The class of models is a generalization of
+two specific models derived by Gaspard and Gilbert as mesoscopic dynamics of
+energies for two-dimensional and three-dimensional locally confined hard-discs.
+They claim some equalities hold between the thermal conductivity and several
+static observables and also conjecture that these equations are universal in
+the sense that they hold for mesoscopic dynamics of energies for confined
+particles interacting through hard-core collisions. In this paper, we give
+sufficient and necessary conditions for these equalities to hold in the class
+we introduce. In particular, we prove that the equality between the thermal
+conductivity and other static observables holds if and only if the model obeys
+the gradient condition. Since the gradient condition does not hold for models
+derived by Gaspard and Gilbert, our result implies a part of their claim is
+incorrect.",1611.08866v1
+2016-12-07,Spatial heterogeneity of W transmutation in a fusion device,"Accurately quantifying the transmutation rate of tungsten (W) under neutron
+irradiation is a necessary requirement in the assessment of its performance as
+an armour material in a fusion power plant. The usual approach of calculating
+average responses, assuming large, homogenised material volumes, is
+insufficient to capture the full complexity of the transmutation picture in the
+context of a realistic fusion power plant design, particularly for rhenium (Re)
+production from W. Combined neutron transport and inventory simulations for
+representative {\it spatially heterogeneous} models of a fusion power plant
+show that the production rate of Re is strongly influenced by the local spatial
+environment. Localised variation in neutron moderation (slowing down) due to
+structural steel and coolant, particularly water, can dramatically increase Re
+production because of the huge cross sections of giant resolved resonances in
+the neutron-capture reaction of \(^{186}\)W at low neutron energies.
+Calculations using cross section data corrected for temperature (Doppler)
+effects suggest that temperature may have a relatively lesser influence on
+transmutation rates.",1612.03892v1
+2017-01-20,Structure of optimal strategies for remote estimation over Gilbert-Elliott channel with feedback,"We investigate remote estimation over a Gilbert-Elliot channel with feedback.
+We assume that the channel state is observed by the receiver and fed back to
+the transmitter with one unit delay. In addition, the transmitter gets ACK/NACK
+feedback for successful/unsuccessful transmission. Using ideas from team
+theory, we establish the structure of optimal transmission and estimation
+strategies and identify a dynamic program to determine optimal strategies with
+that structure. We then consider first-order autoregressive sources where the
+noise process has unimodal and symmetric distribution. Using ideas from
+majorization theory, we show that the optimal transmission strategy has a
+threshold structure and the optimal estimation strategy is Kalman-like.",1701.05943v1
+2017-02-04,Fabrication of Atomically Precise Nanopores in Hexagonal Boron Nitride,"We demonstrate the fabrication of individual nanopores in hexagonal boron
+nitride (hBN) with atomically precise control of the pore size. Previous
+methods of pore production in other 2D materials create pores of irregular
+geometry with imprecise diameters. By taking advantage of the preferential
+growth of boron vacancies in hBN under electron beam irradiation, we are able
+to observe the pore growth via transmission electron microscopy, and terminate
+the process when the pore has reached its desired size. Careful control of beam
+conditions allows us to nucleate and grow individual triangular and hexagonal
+pores with diameters ranging from subnanometer to 6nm over a large area of
+suspended hBN using a conventional TEM. These nanopores could find application
+in molecular sensing, DNA sequencing, water desalination, and molecular
+separation. Furthermore, the chemical edge-groups along the hBN pores can be
+made entirely nitrogen terminated or faceted with boron-terminated edges,
+opening avenues for tailored functionalization and extending the applications
+of these hBN nanopores.",1702.01220v1
+2017-02-10,A finite element approximation for the stochastic Maxwell--Landau--Lifshitz--Gilbert system,"The stochastic Landau--Lifshitz--Gilbert (LLG) equation coupled with the
+Maxwell equations (the so called stochastic MLLG system) describes the creation
+of domain walls and vortices (fundamental objects for the novel nanostructured
+magnetic memories). We first reformulate the stochastic LLG equation into an
+equation with time-differentiable solutions. We then propose a convergent
+$\theta$-linear scheme to approximate the solutions of the reformulated system.
+As a consequence, we prove convergence of the approximate solutions, with no or
+minor conditions on time and space steps (depending on the value of $\theta$).
+Hence, we prove the existence of weak martingale solutions of the stochastic
+MLLG system. Numerical results are presented to show applicability of the
+method.",1702.03027v1
+2017-03-07,The extrapolated explicit midpoint scheme for variable order and step size controlled integration of the Landau-Lifschitz-Gilbert equation,"A practical and efficient scheme for the higher order integration of the
+Landau-Lifschitz-Gilbert (LLG) equation is presented. The method is based on
+extrapolation of the two-step explicit midpoint rule and incorporates adaptive
+time step and order selection. We make use of a piecewise time-linear stray
+field approximation to reduce the necessary work per time step. The
+approximation to the interpolated operator is embedded into the extrapolation
+process to keep in step with the hierarchic order structure of the scheme. We
+verify the approach by means of numerical experiments on a standardized NIST
+problem and compare with a higher order embedded Runge-Kutta formula. The
+efficiency of the presented approach increases when the stray field computation
+takes a larger portion of the costs for the effective field evaluation.",1703.02479v1
+2017-09-06,Adaptively time stepping the stochastic Landau-Lifshitz-Gilbert equation at nonzero temperature: implementation and validation in MuMax3,"Thermal fluctuations play an increasingly important role in micromagnetic
+research relevant for various biomedical and other technological applications.
+Until now, it was deemed necessary to use a time stepping algorithm with a
+fixed time step in order to perform micromagnetic simulations at nonzero
+temperatures. However, Berkov and Gorn have shown that the drift term which
+generally appears when solving stochastic differential equations can only
+influence the length of the magnetization. This quantity is however fixed in
+the case of the stochastic Landau-Lifshitz-Gilbert equation. In this paper, we
+exploit this fact to straightforwardly extend existing high order solvers with
+an adaptive time stepping algorithm. We implemented the presented methods in
+the freely available GPU-accelerated micromagnetic software package MuMax3 and
+used it to extensively validate the presented methods. Next to the advantage of
+having control over the error tolerance, we report a twenty fold speedup
+without a loss of accuracy, when using the presented methods as compared to the
+hereto best practice of using Heun's solver with a small fixed time step.",1709.01682v1
+2017-09-18,Growth-Induced In-Plane Uniaxial Anisotropy in V$_{2}$O$_{3}$/Ni Films,"We report on a strain-induced and temperature dependent uniaxial anisotropy
+in V$_{2}$O$_{3}$/Ni hybrid thin films, manifested through the interfacial
+strain and sample microstructure, and its consequences on the angular dependent
+magnetization reversal. X-ray diffraction and reciprocal space maps identify
+the in-plane crystalline axes of the V$_{2}$O$_{3}$; atomic force and scanning
+electron microscopy reveal oriented rips in the film microstructure.
+Quasi-static magnetometry and dynamic ferromagnetic resonance measurements
+identify a uniaxial magnetic easy axis along the rips. Comparison with films
+grown on sapphire without rips shows a combined contribution from strain and
+microstructure in the V$_{2}$O$_{3}$/Ni films. Magnetization reversal
+characteristics captured by angular-dependent first order reversal curve
+measurements indicate a strong domain wall pinning along the direction
+orthogonal to the rips, inducing an angular-dependent change in the reversal
+mechanism. The resultant anisotropy is tunable with temperature and is most
+pronounced at room temperature, which is beneficial for potential device
+applications.",1709.06100v1
+2018-05-07,Generalized Random Gilbert-Varshamov Codes,"We introduce a random coding technique for transmission over discrete
+memoryless channels, reminiscent of the basic construction attaining the
+Gilbert-Varshamov bound for codes in Hamming spaces. The code construction is
+based on drawing codewords recursively from a fixed type class, in such a way
+that a newly generated codeword must be at a certain minimum distance from all
+previously chosen codewords, according to some generic distance function. We
+derive an achievable error exponent for this construction, and prove its
+tightness with respect to the ensemble average. We show that the exponent
+recovers the Csisz\'{a}r and K{\""o}rner exponent as a special case, which is
+known to be at least as high as both the random-coding and expurgated
+exponents, and we establish the optimality of certain choices of the distance
+function. In addition, for additive distances and decoding metrics, we present
+an equivalent dual expression, along with a generalization to infinite
+alphabets via cost-constrained random coding.",1805.02515v2
+2018-07-04,Deep Autoencoder for Combined Human Pose Estimation and body Model Upscaling,"We present a method for simultaneously estimating 3D human pose and body
+shape from a sparse set of wide-baseline camera views. We train a symmetric
+convolutional autoencoder with a dual loss that enforces learning of a latent
+representation that encodes skeletal joint positions, and at the same time
+learns a deep representation of volumetric body shape. We harness the latter to
+up-scale input volumetric data by a factor of $4 \times$, whilst recovering a
+3D estimate of joint positions with equal or greater accuracy than the state of
+the art. Inference runs in real-time (25 fps) and has the potential for passive
+human behaviour monitoring where there is a requirement for high fidelity
+estimation of human body shape and pose.",1807.01511v1
+2018-10-08,Hiding the weights -- CBC black box algorithms with a guaranteed error bound,"The component-by-component (CBC) algorithm is a method for constructing good
+generating vectors for lattice rules for the efficient computation of
+high-dimensional integrals in the ""weighted"" function space setting introduced
+by Sloan and Wo\'zniakowski. The ""weights"" that define such spaces are needed
+as inputs into the CBC algorithm, and so a natural question is, for a given
+problem how does one choose the weights? This paper introduces two new CBC
+algorithms which, given bounds on the mixed first derivatives of the integrand,
+produce a randomly shifted lattice rule with a guaranteed bound on the
+root-mean-square error. This alleviates the need for the user to specify the
+weights. We deal with ""product weights"" and ""product and order dependent (POD)
+weights"". Numerical tables compare the two algorithms under various assumed
+bounds on the mixed first derivatives, and provide rigorous upper bounds on the
+root-mean-square integration error.",1810.03394v1
+2018-10-11,Alternative Stacking Sequences in Hexagonal Boron Nitride,"The relative orientation of successive sheets, i.e. the stacking sequence, in
+layered two-dimensional materials is central to the electronic, thermal, and
+mechanical properties of the material. Often different stacking sequences have
+comparable cohesive energy, leading to alternative stable crystal structures.
+Here we theoretically and experimentally explore different stacking sequences
+in the van der Waals bonded material hexagonal boron nitride (h-BN). We examine
+the total energy, electronic bandgap, and dielectric response tensor for five
+distinct high symmetry stacking sequences for both bulk and bilayer forms of
+h-BN. Two sequences, the generally assumed AA' sequence and the relatively
+unknown (for h-BN) AB (Bernal) sequence, are predicted to have comparably low
+energy. We present a scalable modified chemical vapor deposition method that
+produces large flakes of virtually pure AB stacked h-BN; this new material
+complements the generally available AA' stacked h-BN.",1810.04814v1
+2018-10-17,Unified theory of magnetization dynamics with relativistic and nonrelativistic spin torques,"Spin torques play a crucial role in operative properties of modern spintronic
+devices. To study current-driven magnetization dynamics, spin-torque terms
+providing the action of spin-polarized currents have previously often been
+added in a phenomenological way to the Landau-Lifshitz-Gilbert equation
+describing the local spin dynamics, yet without derivation from fundamental
+principles. Here, starting from the Dirac-Kohn-Sham theory and incorporating
+nonlocal spin transport we rigorously derive the various spin-torque terms that
+appear in current-driven magnetization dynamics. In particular we obtain an
+extended magnetization dynamics equation that precisely contains the
+nonrelativistic adiabatic and relativistic nonadiabatic spin-transfer torques
+(STTs) of the Berger and Zhang-Li forms as well as relativistic spin-orbit
+torques (SOTs). We derive in addition a previously unnoticed relativistic
+spin-torque term and moreover show that the various obtained spin-torque terms
+do not appear in the same mathematical form in both the Landau-Lifshitz and
+Landau-Lifshitz-Gilbert equations of spin dynamics.",1810.07438v1
+2018-10-23,Resource-Constrained Simultaneous Detection and Labeling of Objects in High-Resolution Satellite Images,"We describe a strategy for detection and classification of man-made objects
+in large high-resolution satellite photos under computational resource
+constraints. We detect and classify candidate objects by using five pipelines
+of convolutional neural network processing (CNN), run in parallel. Each
+pipeline has its own unique strategy for fine tunning parameters, proposal
+region filtering, and dealing with image scales. The conflicting region
+proposals are merged based on region confidence and not just based on overlap
+areas, which improves the quality of the final bounding-box regions selected.
+We demonstrate this strategy using the recent xView challenge, which is a
+complex benchmark with more than 1,100 high-resolution images, spanning 800,000
+aerial objects around the world covering a total area of 1,400 square
+kilometers at 0.3 meter ground sample distance. To tackle the
+resource-constrained problem posed by the xView challenge, where inferences are
+restricted to be on CPU with 8GB memory limit, we used lightweight CNN's
+trained with the single shot detector algorithm. Our approach was competitive
+on sequestered sets; it was ranked third.",1810.10110v1
+2018-11-01,"Ludometrics: Luck, and How to Measure It","Game theory is the study of tractable games which may be used to model more
+complex systems. Board games, video games and sports, however, are intractable
+by design, so ""ludological"" theories about these games as complex phenomena
+should be grounded in empiricism. A first ""ludometric"" concern is the empirical
+measurement of the amount of luck in various games. We argue against a narrow
+view of luck which includes only factors outside any player's control, and
+advocate for a holistic definition of luck as complementary to the variation in
+effective skill within a population of players. We introduce two metrics for
+luck in a game for a given population - one information theoretical, and one
+Bayesian, and discuss the estimation of these metrics using sparse,
+high-dimensional regression techniques. Finally, we apply these techniques to
+compare the amount of luck between various professional sports, between Chess
+and Go, and between two hobby board games: Race for the Galaxy and Seasons.",1811.00673v1
+2019-01-28,Topology and Observables of the Non-Hermitian Chern Insulator,"Topology plays a central role in nearly all disciplines of physics, yet its
+applications have so far been restricted to closed, lossless systems in
+thermodynamic equilibrium. Given that many physical systems are open and may
+include gain and loss mechanisms, there is an eminent need to reexamine
+topology within the context of non-Hermitian theories that describe open, lossy
+systems. The recent generalization of the Chern number to non-Hermitian
+Hamiltonians initiated this reexamination; however, there is so far no
+established connection between a non-Hermitian topological invariant and the
+quantization of an observable. In this work, we show that no such relationship
+exists between the Chern number of non-Hermitian bands and the quantization of
+the Hall conductivity. Using field theoretical techniques, we calculate the
+longitudinal and Hall conductivities of a non-Hermitian Hamiltonian with a
+finite Chern number to explicitly demonstrate the physics of a non-quantized
+Hall conductivity despite an invariable Chern number. These results demonstrate
+that the Chern number does not provide a physically meaningful classification
+of non-Hermitian Hamiltonians.",1901.09961v2
+2019-03-25,Deep Shape from Polarization,"This paper makes a first attempt to bring the Shape from Polarization (SfP)
+problem to the realm of deep learning. The previous state-of-the-art methods
+for SfP have been purely physics-based. We see value in these principled
+models, and blend these physical models as priors into a neural network
+architecture. This proposed approach achieves results that exceed the previous
+state-of-the-art on a challenging dataset we introduce. This dataset consists
+of polarization images taken over a range of object textures, paints, and
+lighting conditions. We report that our proposed method achieves the lowest
+test error on each tested condition in our dataset, showing the value of
+blending data-driven and physics-driven approaches.",1903.10210v2
+2019-04-30,The algebra of rewriting for presentations of inverse monoids,"We describe a formalism, using groupoids, for the study of rewriting for
+presentations of inverse monoids, that is based on the Squier complex
+construction for monoid presentations. We introduce the class of pseudoregular
+groupoids, an example of which now arises as the fundamental groupoid of our
+version of the Squier complex. A further key ingredient is the factorisation of
+the presentation map from a free inverse monoid as the composition of an
+idempotent pure map and an idempotent separating map. The relation module of a
+presentation is then defined as the abelianised kernel of this idempotent
+separating map. We then use the properties of idempotent separating maps to
+derive a free presentation of the relation module. The construction of its
+kernel - the module of identities - uses further facts about pseudoregular
+groupoids.",1904.13135v1
+2019-07-18,"The homology of groups, profinite completions, and echoes of Gilbert Baumslag","We present novel constructions concerning the homology of finitely generated
+groups. Each construction draws on ideas of Gilbert Baumslag. There is a
+finitely presented acyclic group $U$ such that $U$ has no proper subgroups of
+finite index and every finitely presented group can be embedded in $U$. There
+is no algorithm that can determine whether or not a finitely presentable
+subgroup of a residually finite, biautomatic group is perfect. For every
+recursively presented abelian group $A$ there exists a pair of groups
+$i:P_A\hookrightarrow G_A$ such that $i$ induces an isomorphism of profinite
+completions, where $G_A$ is a torsion-free biautomatic group that is residually
+finite and superperfect, while $P_A$ is a finitely generated group with
+$H_2(P_A,\mathbb{Z})\cong A$.",1907.08072v2
+2019-08-08,Semantic Estimation of 3D Body Shape and Pose using Minimal Cameras,"We aim to simultaneously estimate the 3D articulated pose and high fidelity
+volumetric occupancy of human performance, from multiple viewpoint video (MVV)
+with as few as two views. We use a multi-channel symmetric 3D convolutional
+encoder-decoder with a dual loss to enforce the learning of a latent embedding
+that enables inference of skeletal joint positions and a volumetric
+reconstruction of the performance. The inference is regularised via a prior
+learned over a dataset of view-ablated multi-view video footage of a wide range
+of subjects and actions, and show this to generalise well across unseen
+subjects and actions. We demonstrate improved reconstruction accuracy and lower
+pose estimation error relative to prior work on two MVV performance capture
+datasets: Human 3.6M and TotalCapture.",1908.03030v2
+2019-09-06,The universal unramified module for GL(n) and the Ihara conjecture,"Let $F$ be a finite extension of $\mathbb{Q}_p$. Let $W(k)$ denote the Witt
+vectors of an algebraically closed field $k$ of characteristic $\ell$ different
+from $p$ and $2$, and let $\mathcal{Z}$ be the spherical Hecke algebra for
+$GL_n(F)$ over $W(k)$. Given a Hecke character $\lambda:\mathcal{Z}\to R$,
+where $R$ is an arbitrary $W(k)$-algebra, we introduce the universal unramified
+module $\mathcal{M}_{\lambda,R}$. We show $\mathcal{M}_{\lambda,R}$ embeds in
+its Whittaker space and is flat over $R$, resolving a conjecture of Lazarus. It
+follows that $\mathcal{M}_{\lambda,k}$ has the same semisimplification as any
+unramified principle series with Hecke character $\lambda$.
+  In the setting of mod-$\ell$ automorphic forms, Clozel, Harris, and Taylor
+formulate a conjectural analogue of Ihara's lemma. It predicts that every
+irreducible submodule of a certain cyclic module $V$ of mod-$\ell$ automorphic
+forms is generic. Our result on the Whittaker model of
+$\mathcal{M}_{\lambda,k}$ reduces the Ihara conjecture to the statement that
+$V$ is generic.",1909.02709v3
+2019-10-10,Weak-strong uniqueness for the Landau-Lifshitz-Gilbert equation in micromagnetics,"We consider the time-dependent Landau-Lifshitz-Gilbert equation. We prove
+that each weak solution coincides with the (unique) strong solution, as long as
+the latter exists in time. Unlike available results in the literature, our
+analysis also includes the physically relevant lower-order terms like Zeeman
+contribution, anisotropy, stray field, and the Dzyaloshinskii-Moriya
+interaction (which accounts for the emergence of magnetic Skyrmions). Moreover,
+our proof gives a template on how to approach weak-strong uniqueness for even
+more complicated problems, where LLG is (nonlinearly) coupled to other
+(nonlinear) PDE systems.",1910.04630v2
+2019-11-20,Hard Choices in Artificial Intelligence: Addressing Normative Uncertainty through Sociotechnical Commitments,"As AI systems become prevalent in high stakes domains such as surveillance
+and healthcare, researchers now examine how to design and implement them in a
+safe manner. However, the potential harms caused by systems to stakeholders in
+complex social contexts and how to address these remains unclear. In this
+paper, we explain the inherent normative uncertainty in debates about the
+safety of AI systems. We then address this as a problem of vagueness by
+examining its place in the design, training, and deployment stages of AI system
+development. We adopt Ruth Chang's theory of intuitive comparability to
+illustrate the dilemmas that manifest at each stage. We then discuss how
+stakeholders can navigate these dilemmas by incorporating distinct forms of
+dissent into the development pipeline, drawing on Elizabeth Anderson's work on
+the epistemic powers of democratic institutions. We outline a framework of
+sociotechnical commitments to formal, substantive and discursive challenges
+that address normative uncertainty across stakeholders, and propose the
+cultivation of related virtues by those responsible for development.",1911.09005v1
+2019-11-22,Asymmetric entanglement-assisted quantum error-correcting codes and BCH codes,"The concept of asymmetric entanglement-assisted quantum error-correcting code
+(asymmetric EAQECC) is introduced in this article. Codes of this type take
+advantage of the asymmetry in quantum errors since phase-shift errors are more
+probable than qudit-flip errors. Moreover, they use pre-shared entanglement
+between encoder and decoder to simplify the theory of quantum error correction
+and increase the communication capacity. Thus, asymmetric EAQECCs can be
+constructed from any pair of classical linear codes over an arbitrary field.
+Their parameters are described and a Gilbert-Varshamov bound is presented.
+Explicit parameters of asymmetric EAQECCs from BCH codes are computed and
+examples exceeding the introduced Gilbert-Varshamov bound are shown.",1911.10031v2
+2019-12-16,Nanosecond-timescale development of Faraday rotation in an ultracold gas,"When a gas of ultracold atoms is suddenly illuminated by light that is nearly
+resonant with an atomic transition, the atoms cannot respond instantaneously.
+This non-instantaneous response means the gas is initially more transparent to
+the applied light than in steady-state. The timescale associated with the
+development of light absorption is set by the atomic excited state lifetime.
+Similarly, the index of refraction in the gas also requires time to reach a
+steady-state value, but the development of the associated phase response is
+expected to be slower than absorption effects. Faraday rotation is one
+manifestation of differing indices of refraction for orthogonal circular light
+polarization components. We have performed experiments measuring the
+time-dependent development of polarization rotation in an ultracold gas
+subjected to a magnetic field. Our measurements match theoretical predictions
+based on solving optical Bloch equations. We are able to identify how
+parameters such as steady-state optical thickness and applied magnetic field
+strength influence the development of Faraday rotation.",1912.07553v1
+2020-03-24,An information theoretic framework for classifying exoplanetary system architectures,"We propose several descriptive measures to characterize the arrangements of
+planetary masses, periods, and mutual inclinations within exoplanetary systems.
+These measures are based in complexity theory and capture the global,
+system-level trends of each architecture. Our approach considers all planets in
+a system simultaneously, facilitating both intra-system and inter-system
+analysis. We find that based on these measures, Kepler's high-multiplicity
+($N\geq3$) systems can be explained if most systems belong to a single
+intrinsic population, with a subset of high-multiplicity systems ($\sim20\%$)
+hosting additional, undetected planets intermediate in period between the known
+planets. We confirm prior findings that planets within a system tend to be
+roughly the same size and approximately coplanar. We find that forward modeling
+has not yet reproduced the high degree of spacing similarity (in log-period)
+actually seen in the Kepler data. Although our classification scheme was
+developed using compact Kepler multis as a test sample, our methods can be
+immediately applied to any other population of exoplanetary systems. We apply
+this classification scheme to (1) quantify the similarity between systems, (2)
+resolve observational biases from physical trends, and (3) identify which
+systems to search for additional planets and where to look for these planets.",2003.11098v1
+2020-05-14,On the Performance Analysis of Streaming Codes over the Gilbert-Elliott Channel,"The Gilbert-Elliot (GE) channel is a commonly-accepted model for packet
+erasures in networks. Streaming codes are a class of packet-level erasure codes
+designed to provide reliable communication over the GE channel. The design of a
+streaming code may be viewed as a two-step process. In the first, a more
+tractable, delay-constrained sliding window (DCSW) channel model is considered
+as a proxy to the GE channel. The streaming code is then designed to reliably
+recover from all erasures introduced by the DCSW channel model. Simulation is
+typically used to evaluate the performance of the streaming code over the
+original GE channel, as analytic performance evaluation is challenging. In the
+present paper, we take an important first step towards analytical performance
+evaluation. Recognizing that most, efficient constructions of a streaming code
+are based on the diagonal embedding or horizontal embedding of scalar block
+codes within a packet stream, this paper provides upper and lower bounds on the
+block-erasure probability of the underlying scalar block code when operated
+over the GE channel.",2005.06921v2
+2020-08-25,Differentiating a Tensor Language,"How does one compile derivatives of tensor programs, such that the resulting
+code is purely functional (hence easier to optimize and parallelize) and
+provably efficient relative to the original program? We show that naively
+differentiating tensor code---as done in popular systems like Tensorflow and
+PyTorch---can cause asymptotic slowdowns in pathological cases, violating the
+Cheap Gradients Principle. However, all existing automatic differentiation
+methods that guarantee this principle (for variable size data) do so by relying
+on += mutation through aliases/pointers---which complicates downstream
+optimization. We provide the first purely functional, provably efficient,
+adjoint/reverse-mode derivatives of array/tensor code by explicitly accounting
+for sparsity. We do this by focusing on the indicator function from Iverson's
+APL. We also introduce a new ""Tensor SSA"" normal form and a new derivation of
+reverse-mode automatic differentiation based on the universal property of
+inner-products.",2008.11256v1
+2020-09-14,Moduli of Langlands Parameters,"Let $F$ be a nonarchimedean local field of residue characteristic $p$, let
+$\hat{G}$ be a split reductive group over $\mathbb{Z}[1/p]$ with an action of
+$W_F$, and let $^LG$ denote the semidirect product $\hat{G}\rtimes W_F$. We
+construct a moduli space of Langlands parameters $W_F \to {^LG}$, and show that
+it is locally of finite type and flat over $\mathbb{Z}[1/p]$, and that it is a
+reduced local complete intersection. We give parameterizations of the connected
+components and the irreducible components of the geometric fibers of this
+space, and parameterizations of the connected components of the total space
+over $\overline{\mathbb{Z}}[1/p]$ (under mild hypotheses) and over
+$\overline{\mathbb{Z}}_{\ell}$ for $\ell\neq p$. In each case, we show
+precisely how each connected component identifies with the ""principal""
+connected component attached to a smaller split reductive group scheme. Finally
+we study the GIT quotient of this space by $\hat{G}$ and give a complete
+description of its fibers up to homeomorphism, and a complete description of
+its ring of functions after inverting an explicit finite set of primes
+depending only on $^LG$.",2009.06708v3
+2020-09-30,Spin-diffusion model for micromagnetics in the limit of long times,"In this paper, we consider spin-diffusion Landau-Lifshitz-Gilbert equations
+(SDLLG), which consist of the time-dependent Landau-Lifshitz-Gilbert (LLG)
+equation coupled with a time-dependent diffusion equation for the electron spin
+accumulation. The model takes into account the diffusion process of the spin
+accumulation in the magnetization dynamics of ferromagnetic multilayers. We
+prove that in the limit of long times, the system reduces to simpler equations
+in which the LLG equation is coupled to a nonlinear and nonlocal steady-state
+equation, referred to as SLLG. As a by-product, the existence of global weak
+solutions to the SLLG equation is obtained. Moreover, we prove weak-strong
+uniqueness of solutions of SLLG, i.e., all weak solutions coincide with the
+(unique) strong solution as long as the latter exists in time. The results
+provide a solid mathematical ground to the qualitative behavior originally
+predicted by Zhang, Levy, and Fert in [Physical Review Letters 88 (2002)] in
+ferromagnetic multilayers.",2009.14534v1
+2020-12-20,Reconstructing phase-resolved hysteresis loops from first-order reversal curves,"The first order reversal curve (FORC) method is a magnetometry based
+technique used to capture nanoscale magnetic phase separation and interactions
+with macroscopic measurements using minor hysteresis loop analysis. This makes
+the FORC technique a powerful tool in the analysis of complex systems which
+cannot be effectively probed using localized techniques. However, recovering
+quantitative details about the identified phases which can be compared to
+traditionally measured metrics remains an enigmatic challenge. We demonstrate a
+technique to reconstruct phase-resolved magnetic hysteresis loops by
+selectively integrating the measured FORC distribution. From these minor loops,
+the traditional metrics - including the coercivity and saturation field, and
+the remanent and saturation magnetization - can be determined. In order to
+perform this analysis, special consideration must be paid to the accurate
+quantitative management of the so-called reversible features. This technique is
+demonstrated on three representative materials systems, high anisotropy FeCuPt
+thin-films, Fe nanodots, and SmCo/Fe exchange spring magnet films, and shows
+excellent agreement with the direct measured major loop, as well as the phase
+separated loops.",2012.11041v1
+2021-01-13,Self-organization in the one-dimensional Landau-Lifshitz-Gilbert-Slonczewski equation with non-uniform anisotropy fields,"In magnetic films driven by spin-polarized currents, the
+perpendicular-to-plane anisotropy is equivalent to breaking the time
+translation symmetry, i.e., to a parametric pumping. In this work, we
+numerically study those current-driven magnets via the
+Landau-Lifshitz-Gilbert-Slonczewski equation in one spatial dimension. We
+consider a space-dependent anisotropy field in the parametric-like regime. The
+anisotropy profile is antisymmetric to the middle point of the system. We find
+several dissipative states and dynamical behavior and focus on localized
+patterns that undergo oscillatory and phase instabilities. Using numerical
+simulations, we characterize the localized states' bifurcations and present the
+corresponding diagram of phases.",2101.05263v1
+2021-01-20,Global Optimization of the Mean First Passage Time for Narrow Capture Problems in Elliptic Domains,"Narrow escape and narrow capture problems which describe the average times
+required to stop the motion of a randomly travelling particle within a domain
+have applications in various areas of science. While for general domains, it is
+known how the escape time decreases with the increase of the trap sizes, for
+some specific 2D and 3D domains, higher-order asymptotic formulas have been
+established, providing the dependence of the escape time on the sizes and
+locations of the traps. Such results allow the use of global optimization to
+seek trap arrangements that minimize average escape times. In a recent paper
+\cite{iyaniwura2021optimization}, an explicit size- and trap location-dependent
+expansion of the average mean first passage time (MFPT) in a 2D elliptic domain
+was derived. The goal of this work is to systematically seek global minima of
+MFPT for $1\leq N\leq 50$ traps in elliptic domains using global optimization
+techniques, and compare the corresponding putative optimal trap arrangements
+for different values of the domain eccentricity. Further, an asymptotic formula
+the for the average MFPT in elliptic domains with $N$ circular traps of
+arbitrary sizes is derived, and sample optimal configurations involving
+non-equal traps are computed.",2101.08368v2
+2021-02-03,Bounds and Genericity of Sum-Rank-Metric Codes,"We derive simplified sphere-packing and Gilbert--Varshamov bounds for codes
+in the sum-rank metric, which can be computed more efficiently than previous
+ones. They give rise to asymptotic bounds that cover the asymptotic setting
+that has not yet been considered in the literature: families of sum-rank-metric
+codes whose block size grows in the code length. We also provide two genericity
+results: we show that random linear codes achieve almost the sum-rank-metric
+Gilbert--Varshamov bound with high probability. Furthermore, we derive bounds
+on the probability that a random linear code attains the sum-rank-metric
+Singleton bound, showing that for large enough extension fields, almost all
+linear codes achieve it.",2102.02244v3
+2021-03-01,A pathwise stochastic Landau-Lifshitz-Gilbert equation with application to large deviations,"Using a rough path formulation, we investigate existence, uniqueness and
+regularity for the stochastic Landau-Lifshitz-Gilbert equation with
+Stratonovich noise on the one dimensional torus. As a main result we show the
+continuity of the so-called It\^o-Lyons map in the energy spaces
+$L^\infty(0,T;H^k)\cap L^2(0,T;H^{k+1})$ for any $k\ge1$. The proof proceeds in
+two steps. First, based on an energy estimate in the aforementioned space
+together with a compactness argument we prove existence of a unique solution,
+implying the continuous dependence in a weaker norm. This is then strengthened
+in the second step where the continuity in the optimal norm is established
+through an application of the rough Gronwall lemma. Our approach is direct and
+does not rely on any transformation formula, which permits to treat
+multidimensional noise. As an easy consequence we then deduce a Wong-Zakai type
+result, a large deviation principle for the solution and a support theorem.",2103.00926v1
+2021-03-17,Numerical analysis of the Landau-Lifshitz-Gilbert equation with inertial effects,"We consider the numerical approximation of the inertial
+Landau-Lifshitz-Gilbert equation (iLLG), which describes the dynamics of the
+magnetization in ferromagnetic materials at subpicosecond time scales. We
+propose and analyze two fully discrete numerical schemes: The first method is
+based on a reformulation of the problem as a linear constrained variational
+formulation for the linear velocity. The second method exploits a reformulation
+of the problem as a first order system in time for the magnetization and the
+angular momentum. Both schemes are implicit, based on first-order finite
+elements, and generate approximations satisfying the unit-length constraint of
+iLLG at the vertices of the underlying mesh. For both methods, we prove
+convergence of the approximations towards a weak solution of the problem.
+Numerical experiments validate the theoretical results and show the
+applicability of the methods for the simulation of ultrafast magnetic
+processes.",2103.09888v2
+2021-07-12,Human-like Relational Models for Activity Recognition in Video,"Video activity recognition by deep neural networks is impressive for many
+classes. However, it falls short of human performance, especially for
+challenging to discriminate activities. Humans differentiate these complex
+activities by recognising critical spatio-temporal relations among explicitly
+recognised objects and parts, for example, an object entering the aperture of a
+container. Deep neural networks can struggle to learn such critical
+relationships effectively. Therefore we propose a more human-like approach to
+activity recognition, which interprets a video in sequential temporal phases
+and extracts specific relationships among objects and hands in those phases.
+Random forest classifiers are learnt from these extracted relationships. We
+apply the method to a challenging subset of the something-something dataset and
+achieve a more robust performance against neural network baselines on
+challenging activities.",2107.05319v2
+2021-08-17,Small-misorientation toughness in biominerals evolved convergently,"The hardest materials in living organisms are biologically grown crystalline
+minerals, or biominerals, which are also incredibly fracture-tough. Biomineral
+mesostructure includes size, shape, spatial arrangement, and crystal
+orientation of crystallites, observable at the mesoscale (10 nanometer - 10
+micron). Here we show that diverse biominerals, including nacre and prisms from
+mollusk shells, coral skeletons, and tunicate spicules have different
+mesostructures, but they converged to similar, small (<30 degrees)
+misorientations of adjacent crystals at the mesoscale. We show that such small
+misorientations are an effective toughening mechanism. Combining
+Polarization-dependent Imaging Contrast (PIC) mapping of mesostructures and
+Molecular Dynamics (MD) simulations of misoriented bicrystals, we reveal here
+that small misorientations toughen bicrystals, thus explaining why they evolved
+independently but convergently: preventing fracture is a clear evolutionary
+advantage for diverse organisms.",2108.07877v1
+2021-08-19,Evidence for a liquid precursor to biomineral formation,"The crystals in animal biominerals such as sea urchin spines, mollusk shells,
+and coral skeletons, form by attachment of amorphous particles that
+subsequently crystallize. Do these solid amorphous precursor particles have
+liquid precursors? Polymer-induced liquid precursors (PILP), or prenucleation
+clusters coalescing into a liquid precursor to calcium carbonate
+crystallization have been observed extensively in synthetic systems. Molecular
+dynamics simulations also predict liquid-liquid phase separation. However,
+evidence for liquid precursors in natural biominerals remains elusive. Here we
+present Scanning or PhotoEmission Electron Microscopy (SEM, PEEM) evidence
+consistent with a dense liquid-like precursor in regenerating sea urchin
+spines. The observed precursor originates in tissue and ultimately transforms
+into a single crystal of calcite (CaCO3) with complex stereom morphology.",2108.08429v1
+2021-08-22,Factors Enhancing E-Government Service Gaps in a Developing Country Context,"Globally, the discourse of e-government has gathered momentum in public
+service delivery. No country has been left untouched in the implementation of
+e-government. Several government departments and agencies are now using
+information and communication technology (ICTs) to deliver government services
+and information to citizens, other government departments, and businesses.
+However, most of the government departments have not provided all of their
+services electronically or at least the most important ones. Thus, this creates
+a phenomenon of e-government service gaps. The objective of this study was to
+investigate the contextual factors enhancing e-government service gaps in a
+developing country. To achieve this aim, the TOE framework was employed
+together with a qualitative case study to guide data collection and analysis.
+The data was collected through semi-structured interviews from government
+employees who are involved in the implementation of e-government services in
+Zimbabwe as well as from citizens and businesses. Eleven (11) factors were
+identified and grouped under the TOE framework. This research contributes
+significantly to the implementation and utilisation of e-government services in
+Zimbabwe. The study also contributes to providing a strong theoretical
+understanding of the factors that enhance e-government service gaps explored in
+the research model.",2108.09803v1
+2021-09-23,Cyclically presented groups as Labelled Oriented Graph groups,"We use results concerning the Smith forms of circulant matrices to identify
+when cyclically presented groups have free abelianisation and so can be
+Labelled Oriented Graph (LOG) groups. We generalize a theorem of Odoni and
+Cremona to show that for a fixed defining word, whose corresponding representer
+polynomial has an irreducible factor that is not cyclotomic and not equal to
+$\pm t$, there are at most finitely many $n$ for which the corresponding
+$n$-generator cyclically presented group has free abelianisation. We classify
+when Campbell and Robertson's generalized Fibonacci groups $H(r,n,s)$ are LOG
+groups and when the Sieradski groups are LOG groups. We prove that amongst
+Johnson and Mawdesley's groups of Fibonacci type, the only ones that can be LOG
+groups are Gilbert-Howie groups $H(n,m)$. We conjecture that if a Gilbert-Howie
+group is a LOG group, then it is a Sieradski group, and prove this in certain
+cases (in particular, for fixed $m$, the conjecture can only be false for
+finitely many $n$). We obtain necessary conditions for a cyclically presented
+group to be a connected LOG group in terms of the representer polynomial and
+apply them to the Prishchepov groups.",2109.11463v1
+2021-12-03,Spectral reconstruction in NRQCD via the Backus-Gilbert method,"We present progress results from the FASTSUM collaboration's programme to
+determine the spectrum of the bottomonium system as a function of temperature
+using a variety of approaches. In this contribution, the Backus Gilbert method
+is used to reconstruct spectral functions from NRQCD meson correlator data from
+FASTSUM's anisotropic ensembles at nonzero temperature. We focus in particular
+on the resolving power of the method, providing a demonstration of how the
+underlying resolution functions can be probed by exploiting the Laplacian
+nature of the NRQCD kernel. We conclude with estimates of the bottomonium
+ground state mass and widths at nonzero temperature.",2112.02075v2
+2021-12-23,Energy minimizing maps with prescribed singularities and Gilbert-Steiner optimal networks,"We investigate the relation between energy minimizing maps valued into
+spheres having topological singularities at given points and optimal networks
+connecting them (e.g. Steiner trees, Gilbert-Steiner irrigation networks). We
+show the equivalence of the corresponding variational problems, interpreting in
+particular the branched optimal transport problem as a homological Plateau
+problem for rectifiable currents with values in a suitable normed group. This
+generalizes the pioneering work by Brezis, Coron and Lieb [10].",2112.12511v4
+2022-02-02,Asymptotic stability of precessing domain walls for the Landau-Lifshitz-Gilbert equation in a nanowire with Dzyaloshinskii-Moriya interaction,"We consider a ferromagnetic nanowire and we focus on an asymptotic regime
+where the Dzyaloshinskii-Moriya interaction is taken into account. First we
+prove a dimension reduction result via $\Gamma$-convergence that determines a
+limit functional $E$ defined for maps $m:\mathbb{R}\to \mathbb{S}^2$ in the
+direction $e_1$ of the nanowire. The energy functional $E$ is invariant under
+translations in $e_1$ and rotations about the axis $e_1$. We fully classify the
+critical points of finite energy $E$ when a transition between $-e_1$ and $e_1$
+is imposed; these transition layers are called (static) domain walls. The
+evolution of a domain wall by the Landau-Lifshitz-Gilbert equation associated
+to $E$ under the effect of an applied magnetic field $h(t)e_1$ depending on the
+time variable $t$ gives rise to the so-called precessing domain wall. Our main
+result proves the asymptotic stability of precessing domain walls for small $h$
+in $L^\infty([0, +\infty))$ and small $H^1(\mathbb{R})$ perturbations of the
+static domain wall, up to a gauge which is intrinsic to invariances of the
+functional $E$.",2202.01005v1
+2022-02-14,The Higgs Boson Mass as Fundamental Parameter of the Minimal Supersymmetric Standard Model,"In the Minimal Supersymmetric Standard Model (MSSM) the mass of the lightest
+neutral Higgs boson is determined by the supersymmetric parameters. In the
+$m_h$MSSM the precisely measured Higgs boson replaces the trilinear coupling
+$A_t$ as input parameter. Expressions are derived to extract $A_t$ in a
+semi-analytical form as a function of the light Higgs boson (pole) mass. An
+algorithm is developed and implemented at two--loop precision, generalizable to
+higher orders, to perform this inversion consistently. The result of the
+algorithm, implemented in the SuSpect spectrum calculator, is illustrated on a
+parameter set compatible with LHC measurements.",2202.06919v2
+2022-02-15,Coding and Bounds for Partially Defective Memory Cells,"This paper considers coding for so-called partially stuck (defect) memory
+cells. Such memory cells can only store partial information as some of their
+levels cannot be used fully due to, e.g., wearout. First, we present new
+constructions that are able to mask $u$ partially stuck cells while correcting
+at the same time $t$ random errors. The process of ""masking"" determines a word
+whose entries coincide with writable levels at the (partially) stuck cells. For
+$u>1$ and alphabet size $q>2$, our new constructions improve upon the required
+redundancy of known constructions for $t=0$, and require less redundancy for
+masking partially stuck cells than former works required for masking fully
+stuck cells (which cannot store any information). Second, we show that treating
+some of the partially stuck cells as erroneous cells can decrease the required
+redundancy for some parameters. Lastly, we derive Singleton-like,
+sphere-packing-like, and Gilbert--Varshamov-like bounds. Numerical comparisons
+state that our constructions match the Gilbert--Varshamov-like bounds for
+several code parameters, e.g., BCH codes that contain all-one word by our first
+construction.",2202.07541v1
+2022-03-24,Multi-platform Process Flow Models and Algorithms for Extraction and Documentation of Digital Forensic Evidence from Mobile Devices,"The increasing need for the examination of evidence from mobile and portable
+gadgets increases the essential need to establish dependable measures for the
+investigation of these gadgets. Many differences exist while detailing the
+requirement for the examination of each gadget, to help detectives and
+examiners in guaranteeing that of any kind piece of evidence extracted/
+collected from any mobile devices is well documented and the outcomes can be
+repeatable, a reliable and well-documented investigation process must be
+implemented if the results of the examination are to be repeatable and
+defensible in courts of law. In this paper we developed a generic process flow
+model for the extraction of digital evidence in mobile devices running on
+android, Windows, iOs and Blackberry operating system. The research adopted
+survey approach and extensive literature review a s means to collect data. The
+models developed were validate through expert opinion. Results of this work can
+guide solution developers in ensuring standardization of evidence extraction
+tools for mobile devices.",2203.13258v1
+2022-06-07,Implicit biases in transit models using stellar pseudo-density,"The transit technique is responsible for the majority of exoplanet
+discoveries to date. Characterizing these planets involves careful modeling of
+their transit profiles. A common technique involves expressing the transit
+duration using a density-like parameter, $\tilde{\rho}$, often called the
+""circular density."" Most notably, the Kepler project -- the largest analysis of
+transit lightcurves to date -- adopted a linear prior on $\tilde{\rho}$. Here,
+we show that such a prior biases measurements of impact parameter, $b$, due to
+the non-linear relationship between $\tilde{\rho}$ and transit duration. This
+bias slightly favors low values ($b \lesssim 0.3$) and strongly disfavors high
+values ($b \gtrsim 0.7$) unless transit signal-to-noise ratio is sufficient to
+provide an independent constraint on $b$, a criterion that is not satisfied for
+the majority of Kepler planets. Planet-to-star radius ratio, $r$, is also
+biased due to $r{-}b$ covariance. Consequently, the median Kepler DR25 target
+suffers a $1.6\%$ systematic underestimate of $r$. We present a techniques for
+correcting these biases and for avoiding them in the first place.",2206.03432v1
+2022-09-12,GenLoco: Generalized Locomotion Controllers for Quadrupedal Robots,"Recent years have seen a surge in commercially-available and affordable
+quadrupedal robots, with many of these platforms being actively used in
+research and industry. As the availability of legged robots grows, so does the
+need for controllers that enable these robots to perform useful skills.
+However, most learning-based frameworks for controller development focus on
+training robot-specific controllers, a process that needs to be repeated for
+every new robot. In this work, we introduce a framework for training
+generalized locomotion (GenLoco) controllers for quadrupedal robots. Our
+framework synthesizes general-purpose locomotion controllers that can be
+deployed on a large variety of quadrupedal robots with similar morphologies. We
+present a simple but effective morphology randomization method that
+procedurally generates a diverse set of simulated robots for training. We show
+that by training a controller on this large set of simulated robots, our models
+acquire more general control strategies that can be directly transferred to
+novel simulated and real-world robots with diverse morphologies, which were not
+observed during training.",2209.05309v1
+2022-10-11,Element-Specific First Order Reversal Curves Measured by Magnetic Transmission X-ray Microscopy,"The first order reversal curve (FORC) method is a macroscopic measurement
+technique which can be used to extract quantitative, microscopic properties of
+hysteretic systems. Using magnetic transmission X-ray microscopy (MTXM), local
+element-specific FORC measurements are performed on a 20 nm thick film of CoTb.
+The FORCs measured with microscopy reveal a step-by-step domain evolution under
+the magnetic field cycling protocol, and provide a direct visualization of the
+mechanistic interpretation of FORC diagrams. They are compared with
+magnetometry FORCs and show good quantitative agreement. Furthermore, the high
+spatial resolution and element-specific sensitivity of MTXM provide new
+capabilities to measure FORCs on small regions or specific phases within
+multicomponent systems, including buried layers in heterostructures. The
+ability to perform FORCs on very small features is demonstrated with the
+MTXM-FORC measurement of a rectangular microstructure with vortex-like Landau
+structures. This work demonstrates the confluence of two uniquely powerful
+techniques to achieve quantitative insight into nanoscale magnetic behavior.",2210.05739v1
+2022-11-08,Landau-Lifshitz-Gilbert equations: Controllability by Low Modes Forcing for deterministic version and Support Theorems for Stochastic version,"In this article, we study the controllability issues of the
+Landau-Lifshitz-Gilbert Equations (LLGEs), accompanied with non-zero exchange
+energy only, in an interval in one spatial dimension with Neumann boundary
+conditions. The paper is of twofold. In the first part of the paper, we study
+the controllability issues of the LLGEs. The control force acting here is
+degenerate i.e., it acts through a few numbers of low mode frequencies. We
+exploit the Fourier series expansion of the solution. We borrow methods of
+differential geometric control theory (Lie bracket generating property) to
+establish the global controllability of the finite-dimensional Galerkin
+approximations of LLGEs. We show $L^2$ approximate controllability of the full
+system. In the second part, we consider the LLGEs with lower-dimensional
+degenerate random forcing (finite-dimensional Brownian motions) and study
+support theorems.",2211.04204v1
+2022-11-18,Knowledge Graph Refinement based on Triplet BERT-Networks,"Knowledge graph embedding techniques are widely used for knowledge graph
+refinement tasks such as graph completion and triple classification. These
+techniques aim at embedding the entities and relations of a Knowledge Graph
+(KG) in a low dimensional continuous feature space. This paper adopts a
+transformer-based triplet network creating an embedding space that clusters the
+information about an entity or relation in the KG. It creates textual sequences
+from facts and fine-tunes a triplet network of pre-trained transformer-based
+language models. It adheres to an evaluation paradigm that relies on an
+efficient spatial semantic search technique. We show that this evaluation
+protocol is more adapted to a few-shot setting for the relation prediction
+task. Our proposed GilBERT method is evaluated on triplet classification and
+relation prediction tasks on multiple well-known benchmark knowledge graphs
+such as FB13, WN11, and FB15K. We show that GilBERT achieves better or
+comparable results to the state-of-the-art performance on these two refinement
+tasks.",2211.10460v1
+2022-11-22,Generalized Random Gilbert-Varshamov Codes: Typical Error Exponent and Concentration Properties,"We find the exact typical error exponent of constant composition generalized
+random Gilbert-Varshamov (RGV) codes over DMCs channels with generalized
+likelihood decoding. We show that the typical error exponent of the RGV
+ensemble is equal to the expurgated error exponent, provided that the RGV
+codebook parameters are chosen appropriately. We also prove that the random
+coding exponent converges in probability to the typical error exponent, and the
+corresponding non-asymptotic concentration rates are derived. Our results show
+that the decay rate of the lower tail is exponential while that of the upper
+tail is double exponential above the expurgated error exponent. The explicit
+dependence of the decay rates on the RGV distance functions is characterized.",2211.12238v1
+2023-01-05,Improved Gilbert-Varshamov bounds for hopping cyclic codes and optical orthogonal codes,"Hopping cyclic codes (HCCs) are (non-linear) cyclic codes with the additional
+property that the $n$ cyclic shifts of every given codeword are all distinct,
+where $n$ is the code length. Constant weight binary hopping cyclic codes are
+also known as optical orthogonal codes (OOCs). HCCs and OOCs have various
+practical applications and have been studied extensively over the years.
+  The main concern of this paper is to present improved Gilbert-Varshamov type
+lower bounds for these codes, when the minimum distance is bounded below by a
+linear factor of the code length. For HCCs, we improve the previously best
+known lower bound of Niu, Xing, and Yuan by a linear factor of the code length.
+For OOCs, we improve the previously best known lower bound of Chung, Salehi,
+and Wei, and Yang and Fuja by a quadratic factor of the code length. As
+by-products, we also provide improved lower bounds for frequency hopping
+sequences sets and error-correcting weakly mutually uncorrelated codes. Our
+proofs are based on tools from probability theory and graph theory, in
+particular the McDiarmid's inequality on the concentration of Lipschitz
+functions and the independence number of locally sparse graphs.",2301.02042v1
+2023-01-11,Thou Shalt not Pick all Items if Thou are First: of Strategyproof and Fair Picking Sequences,"When allocating indivisible items to agents, it is known that the only
+strategyproof mechanisms that satisfy a set of rather mild conditions are
+constrained serial dictatorships: given a fixed order over agents, at each step
+the designated agent chooses a given number of items (depending on her position
+in the sequence). With these rules, also known as non-interleaving picking
+sequences, agents who come earlier in the sequence have a larger choice of
+items. However, this advantage can be compensated by a higher number of items
+received by those who come later. How to balance priority in the sequence and
+number of items received is a nontrivial question. We use a previous model,
+parameterized by a mapping from ranks to scores, a social welfare functional,
+and a distribution over preference profiles. For several meaningful choices of
+parameters, we show that the optimal sequence can be computed in polynomial
+time. Last, we give a simple procedure for eliciting scoring vectors and we
+study the impact of the assignment from agents to positions on the ex-post
+social welfare.",2301.06086v1
+2023-01-17,Comparison of Optical and Electrical Links for Highly-Interconnected Systems,"As data rates for multi-gigabit serial interfaces within multi-node compute
+systems approach and exceed 10 Gigabits per second (Gbps), board-to-board and
+chip-to-chip optical signaling solutions become more attractive, particularly
+for longer (e.g. 50-100 cm) links. The transition to optical signaling will
+potentially allow new high performance compute (HPC) system architectures that
+benefit from characteristics unique to optical links.
+  To examine these characteristics, we built and tested several optical
+demonstration vehicles; one based on dense wavelength division multiplexing
+(DWDM), and others based on multiple point-to-point links carried across
+multimode fibers. All test vehicles were constructed to evaluate applicability
+to a multi-node compute system. Test results, combined with data from recent
+research efforts are summarized and compared to equivalent electrical links and
+the advantages and design characteristics unique to optical signaling are
+identified.",2301.10169v1
+2023-01-17,PWB Manufacturing Variability Effects on High Speed SerDes Links: Statistical Insights from Thousands of 4-Port SParameter Measurements,"Variability analysis is important in successfully deploying multi-gigabit
+backplane printed wiring boards (PWBs) with growing numbers of high-speed
+SerDes links. We discuss the need for large sample sizes to obtain accurate
+variability estimates of SI metrics (eye height, phase skew, etc).
+  Using a dataset of 11,961 S-parameters, we demonstrate statistical techniques
+to extract accurate estimates of PWB SI performance variations. We cite
+numerical examples illustrating how these variations may contribute to
+underestimated or overestimated design criteria, causing unnecessary design
+expense. Tabular summaries of performance variation and key findings of broad
+interest to the general SI community are highlighted.",2301.10176v1
+2023-01-17,"A Zero Sum Signaling Method for High Speed, Dense Parallel Bus Communications","Complex digital systems such as high performance computers (HPCs) make
+extensive use of high-speed electrical interconnects, in routing signals among
+processing elements, or between processing elements and memory. Despite
+increases in serializer/deserializer (SerDes) and memory interface speeds,
+there is demand for higher bandwidth busses in constrained physical spaces
+which still mitigate simultaneous switching noise (SSN). The concept of zero
+sum signaling utilizes coding across a data bus to allow the use of
+single-ended buffers while still mitigating SSN, thereby reducing the number of
+physical channels (e.g. circuit board traces) by nearly a factor of two when
+compared with traditional differential signaling. Through simulation and
+analysis of practical (non-ideal) data bus and power delivery network
+architectures, we demonstrate the feasibility of zero sum signaling and compare
+performance with that of traditional (single-ended and differential) methods.",2302.05427v1
+2023-03-20,Dynamic Documentation for AI Systems,"AI documentation is a rapidly-growing channel for coordinating the design of
+AI technologies with policies for transparency and accessibility. Calls to
+standardize and enact documentation of algorithmic harms and impacts are now
+commonplace. However, documentation standards for AI remain inchoate, and fail
+to match the capabilities and social effects of increasingly impactful
+architectures such as Large Language Models (LLMs). In this paper, we show the
+limits of present documentation protocols, and argue for dynamic documentation
+as a new paradigm for understanding and evaluating AI systems. We first review
+canonical approaches to system documentation outside the context of AI,
+focusing on the complex history of Environmental Impact Statements (EISs). We
+next compare critical elements of the EIS framework to present challenges with
+algorithmic documentation, which have inherited the limitations of EISs without
+incorporating their strengths. These challenges are specifically illustrated
+through the growing popularity of Model Cards and two case studies of
+algorithmic impact assessment in China and Canada. Finally, we evaluate more
+recent proposals, including Reward Reports, as potential components of fully
+dynamic AI documentation protocols.",2303.10854v1
+2023-01-17,"56 Gbps PCB Design Strategies for Clean, Low-Skew Channels","Although next generation (>28 Gbps) SerDes standards have been contemplated
+for several years, it has not been clear whether PCB structures supporting 56
+Gbps NRZ will be feasible and practical. In this paper, we assess a number of
+specific PCB design strategies (related to pin-field breakouts, via stubs, and
+fiber weave skew) both through simulation and through measurement of a wide
+range of structures on a PCB test vehicle. We demonstrate that conventional
+approaches in many cases will not be sufficient, but that modest
+(manufacturable) design changes can enable low-skew 56 Gbps NRZ channels having
+acceptable insertion and return loss.",2304.01909v1
+2023-01-17,Inverting the SerDes Link Design Flow Process,"The traditional SerDes link simulation process begins with the extraction of
+printed circuit board (PCB) physical stripline and via models, followed by
+channel modeling and link simulation. We invert this simulation flow by first
+creating link performance curves across an array of hypothetical channels
+defined with specially-developed, high level, equation-based models; limited
+physical extraction is later undertaken to relate PCB channel implementation to
+these performance curves. These curves allow us to determine the system-level
+SerDes channel requirements and to become better informed in choosing PCB
+technologies for lower cost and easier manufacturability. The inverted modeling
+process is very efficient, allowing for the rapid identification and avoidance
+of problematic channel topologies and the study of other potentially useful
+channel designs.",2304.01911v1
+2023-01-17,Plated-Through-Hole Via Design Specifications for 112G Serial Links,"An earlier study of a high layer-count test board using plated-through-hole
+(PTH) vias and a limited quantity of laser vias was shown to be capable of
+supporting 112 Gb/s PAM-4 links (or equivalent signaling having 28 GHz
+(Nyquist) bandwidth). This original board design was then rebuilt using a
+different fabricator, and the test results revealed a significant decrease in
+the bandwidth of the vias. These results led to the development of a set of
+design specifications that PCB vendors can easily validate, which will ensure
+that the use of high layer-count boards with PTH technology are viable for
+emerging 112 Gb/s PAM-4 links.",2304.01913v1
+2023-04-18,Sample-and-Hold Safety with Control Barrier Functions,"A common assumption on the deployment of safeguarding controllers on the
+digital platform is that high sampling frequency translates to a small
+violation of safety. This paper investigates and formalizes this assumption
+through the lens of Input-to-State Safety. From this perspective, and
+leveraging control barrier functions (CBFs), we propose an alternative solution
+for maintaining safety of sample-and-hold controlled systems without any
+violation to the original safe set. Our approach centers around modulating the
+sampled control input in order to guarantee a more robust safety condition. We
+analyze both the time-triggered and the event-triggered sample-and-hold
+implementations, including the characterization of sampling frequency
+requirements and trigger conditions. We demonstrate the effectiveness of our
+approach in the context of adaptive cruise control through simulations.",2304.08685v2
+2023-01-17,Efficient Circuit-Level Implementation of Knuth-Based Balanced and Nearly-Balanced Codes,"Coding schemes are often used in high-speed processor-processor or
+processor-memory busses in digital systems. In particular, we have introduced
+(in a 2012 DesignCon paper) a zero sum (ZS) signaling method which uses
+balanced or nearly-balanced coding to reduce simultaneous switching noise (SSN)
+in a single-ended bus to a level comparable to that of differential signaling.
+While several balanced coding schemes are known, few papers exist that describe
+the necessary digital hardware implementations of (known) balanced coding
+schemes, and no algorithms had previously been developed for nearly-balanced
+coding. In this work, we extend a known balanced coding scheme to accommodate
+nearly-balanced coding and demonstrate a range of coding and decoding circuits
+through synthesis in 65 nm CMOS. These hardware implementations have minimal
+impact on the energy efficiency and area when compared to current
+serializer/deserializers (SerDes) at clock rates which would support SerDes
+integration.",2304.13497v1
+2023-01-17,Capacitor Optimization in Power Distribution Networks Using Numerical Computation Techniques,"This paper presents a power distribution network (PDN) decoupling capacitor
+optimization application with three primary goals: reduction of solution times
+for large networks, development of flexible network scoring routines, and a
+concentration strictly on achieving the best network performance. Example
+optimizations are performed using broadband models of a printed circuit board
+(PCB), a chip-package, on-die networks, and candidate capacitors. A novel
+worst-case time-domain optimization technique is presented as an alternative to
+the traditional frequency-domain approach. The trade-offs and criteria for
+scoring the computed network are presented. The output is a recommended set of
+capacitors which can then be applied to the product design.",2305.01540v1
+2023-05-26,Sphaleron rate from a modified Backus-Gilbert inversion method,"We compute the sphaleron rate in quenched QCD for a temperature $T \simeq
+1.24~T_c$ from the inversion of the Euclidean lattice time correlator of the
+topological charge density. We explore and compare two different strategies:
+one follows a new approach proposed in this study and consists in extracting
+the rate from finite lattice spacing correlators, and then in taking the
+continuum limit at fixed smoothing radius followed by a zero-smoothing
+extrapolation; the other follows the traditional approach of extracting the
+rate after performing such double extrapolation directly on the correlator. In
+both cases the rate is obtained from a recently-proposed modification of the
+standard Backus-Gilbert procedure. The two strategies lead to compatible
+estimates within errors, which are then compared to previous results in the
+literature at the same or similar temperatures; the new strategy permits to
+obtain improved results, in terms of statistical and systematic uncertainties.",2305.17120v2
+2023-07-21,Visibility graph-based covariance functions for scalable spatial analysis in nonconvex domains,"We present a new method for constructing valid covariance functions of
+Gaussian processes over irregular nonconvex spatial domains such as water
+bodies, where the geodesic distance agrees with the Euclidean distance only for
+some pairs of points. Standard covariance functions based on geodesic distances
+are not positive definite on such domains. Using a visibility graph on the
+domain, we use the graphical method of ""covariance selection"" to propose a
+class of covariance functions that preserve Euclidean-based covariances between
+points that are connected through the domain. The proposed method preserves the
+partially Euclidean nature of the intrinsic geometry on the domain while
+maintaining validity (positive definiteness) and marginal stationarity over the
+entire parameter space, properties which are not always fulfilled by existing
+approaches to construct covariance functions on nonconvex domains. We provide
+useful approximations to improve computational efficiency, resulting in a
+scalable algorithm. We evaluate the performance of competing state-of-the-art
+methods using simulation studies on a contrived nonconvex domain. The method is
+applied to data regarding acidity levels in the Chesapeake Bay, showing its
+potential for ecological monitoring in real-world spatial applications on
+irregular domains.",2307.11941v2
+2023-08-23,Consistency of common spatial estimators under spatial confounding,"This paper addresses the asymptotic performance of popular spatial regression
+estimators on the task of estimating the effect of an exposure on an outcome in
+the presence of an unmeasured spatially-structured confounder. This setting is
+often referred to as ""spatial confounding."" We consider spline models, Gaussian
+processes (GP), generalized least squares (GLS), and restricted spatial
+regression (RSR) under two data generation processes: one where the confounder
+is a fixed effect and one where it is a random effect. The literature on
+spatial confounding is confusing and contradictory, and our results correct and
+clarify several misunderstandings. We first show that, like an unadjusted OLS
+estimator, RSR is asymptotically biased under any spatial confounding scenario.
+We then prove a novel result on the consistency of the GLS estimator under
+spatial confounding. We finally prove that estimators like GLS, GP, and
+splines, that are consistent under confounding by a fixed effect will also be
+consistent under confounding by a random effect. We conclude that, contrary to
+much of the recent literature on spatial confounding, traditional estimators
+based on partially linear models are amenable to estimating effects in the
+presence of spatial confounding. We support our theoretical arguments with
+simulation studies.",2308.12181v1
+2023-09-19,Stochastic control of the Landau-Lifshitz-Gilbert equation,"We consider the stochastic Landau-Lifshitz-Gilbert equation in dimension 1. A
+control process is added to the effective field. We show the existence of a
+weak martingale solution for the resulting controlled equation. The proof uses
+the classical Faedo-Galerkin approximation, along with the Jakubowski version
+of the Skorohod Theorem. We then show pathwise uniqueness for the obtained
+solution, which is then coupled with the theory of Yamada and Watanabe to give
+the existence of a unique strong solution. We then show, using some semigroup
+techniques that the obtained solution satisfies the maximum regularity. We then
+show the existence of an optimal control. A main ingredient of the proof is
+using the compact embedding of a space into itself, albeit with the weak
+topology.",2309.10260v1
+2023-10-18,Parallel-in-Time Integration of the Landau-Lifshitz-Gilbert Equation with the Parallel Full Approximation Scheme in Space and Time,"Speeding up computationally expensive problems, such as numerical simulations
+of large micromagnetic systems, requires efficient use of parallel computing
+infrastructures. While parallelism across space is commonly exploited in
+micromagnetics, this strategy performs poorly once a minimum number of degrees
+of freedom per core is reached. We use magnum.pi, a finite-element
+micromagnetic simulation software, to investigate the Parallel Full
+Approximation Scheme in Space and Time (PFASST) as a space- and time-parallel
+solver for the Landau-Lifshitz-Gilbert equation (LLG). Numerical experiments
+show that PFASST enables efficient parallel-in-time integration of the LLG,
+significantly improving the speedup gained from using a given number of cores
+as well as allowing the code to scale beyond spatial limits.",2310.11819v1
+2023-12-29,Chebyshev and Backus-Gilbert reconstruction for inclusive semileptonic $B_{(s)}$-meson decays from Lattice QCD,"We present a study on the nonperturbative calculation of observables for
+inclusive semileptonic decays of $B_{(s)}$ mesons using lattice QCD. We focus
+on the comparison of two different methods to analyse the lattice data of
+Euclidean correlation functions, specifically Chebyshev and Backus-Gilbert
+approaches. This type of computation may eventually provide new insight into
+the long-standing tension between the inclusive and exclusive determinations of
+the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements $|V_{cb}|$ and $|V_{ub}|$.
+We report the results from a pilot lattice computation for the decay $B_s
+\rightarrow X_c \, l\nu_l$, where the valence quark masses are approximately
+tuned to their physical values using the relativistic-heavy quark action for
+the $b$ quark and the domain-wall formalism for the other valence quarks. We
+address the computation of the total decay rate as well as leptonic and
+hadronic moments, discussing similarities and differences between the two
+analysis techniques.",2312.17401v1
+2024-02-22,Gilbert-Varshamov Bound for Codes in $L_1$ Metric using Multivariate Analytic Combinatorics,"Analytic combinatorics in several variables refers to a suite of tools that
+provide sharp asymptotic estimates for certain combinatorial quantities. In
+this paper, we apply these tools to determine the Gilbert--Varshamov lower
+bound on the rate of optimal codes in $L_1$ metric. Several different code
+spaces are analyzed, including the simplex and the hypercube in $\mathbb{Z^n}$,
+all of which are inspired by concrete data storage and transmission models such
+as the sticky insertion channel, the permutation channel, the adjacent
+transposition (bit-shift) channel, the multilevel flash memory channel, etc.",2402.14712v1
+2024-02-28,Embodied Supervision: Haptic Display of Automation Command to Improve Supervisory Performance,"A human operator using a manual control interface has ready access to their
+own command signal, both by efference copy and proprioception. In contrast, a
+human supervisor typically relies on visual information alone. We propose
+supplying a supervisor with a copy of the operators command signal,
+hypothesizing improved performance, especially when that copy is provided
+through haptic display. We experimentally compared haptic with visual access to
+the command signal, quantifying the performance of N equals 10 participants
+attempting to determine which of three reference signals was being tracked by
+an operator. Results indicate an improved accuracy in identifying the tracked
+target when haptic display was available relative to visual display alone. We
+conjecture the benefit follows from the relationship of haptics to the
+supervisor's own experience, perhaps muscle memory, as an operator.",2402.18707v1
+2024-03-14,Quantum analog of Landau-Lifshitz-Gilbert dynamics,"The Landau-Lifshitz-Gilbert (LLG) and Landau-Lifshitz (LL) equations play an
+essential role for describing the dynamics of magnetization in solids. While a
+quantum analog of the LL dynamics has been proposed in [Phys. Rev. Lett. 110,
+147201 (2013)], the corresponding quantum version of LLG remains unknown. Here,
+we propose such a quantum LLG equation that inherently conserves purity of the
+quantum state. We examine the quantum LLG dynamics of a dimer consisting of two
+interacting spin-1/2 particles. Our analysis reveals that, in the case of
+ferromagnetic coupling, the evolution of initially uncorrelated spins mirrors
+the classical LLG dynamics. However, in the antiferromagnetic scenario, we
+observe pronounced deviations from classical behavior, underscoring the unique
+dynamics of becoming a spinless state, which is non-locally correlated.
+Moreover, when considering spins that are initially correlated, our study
+uncovers an unusual form of transient quantum correlation dynamics, which
+differ significantly from what is typically seen in open quantum systems.",2403.09255v1
+2024-03-15,Identification and estimation of mediational effects of longitudinal modified treatment policies,"We demonstrate a comprehensive semiparametric approach to causal mediation
+analysis, addressing the complexities inherent in settings with longitudinal
+and continuous treatments, confounders, and mediators. Our methodology utilizes
+a nonparametric structural equation model and a cross-fitted sequential
+regression technique based on doubly robust pseudo-outcomes, yielding an
+efficient, asymptotically normal estimator without relying on restrictive
+parametric modeling assumptions. We are motivated by a recent scientific
+controversy regarding the effects of invasive mechanical ventilation (IMV) on
+the survival of COVID-19 patients, considering acute kidney injury (AKI) as a
+mediating factor. We highlight the possibility of ""inconsistent mediation,"" in
+which the direct and indirect effects of the exposure operate in opposite
+directions. We discuss the significance of mediation analysis for scientific
+understanding and its potential utility in treatment decisions.",2403.09928v1
+2024-03-22,Two-scale Analysis for Multiscale Landau-Lifshitz-Gilbert Equation: Theory and Numerical Methods,"This paper discusses the theory and numerical method of two-scale analysis
+for the multiscale Landau-Lifshitz-Gilbert equation in composite ferromagnetic
+materials. The novelty of this work can be summarized in three aspects:
+Firstly, the more realistic and complex model is considered, including the
+effects of the exchange field, anisotropy field, stray field, and external
+magnetic field. The explicit convergence orders in the $H^1$ norm between the
+classical solution and the two-scale solution are obtained. Secondly, we
+propose a robust numerical framework, which is employed in several
+comprehensive experiments to validate the convergence results for the Periodic
+and Neumann problems. Thirdly, we design an improved implicit numerical scheme
+to reduce the required number of iterations and relaxes the constraints on the
+time step size, which can significantly improve computational efficiency.
+Specifically, the projection and the expansion methods are given to overcome
+the inherent non-consistency in the initial data between the multiscale problem
+and homogenized problem.",2403.14957v1
+2020-11-30,Role of Compressive Viscosity and Thermal Conductivity on the Damping of Slow Waves in the Coronal Loops With and Without Heating-Cooling Imbalance,"In the present paper, we derive a new dispersion relation for slow
+magnetoacoustic waves invoking the effect of thermal conductivity, compressive
+viscosity, radiation and unknown heating term along with the consideration of
+heating cooling imbalance from linearized MHD equations. We solve the general
+dispersion relation to understand role of compressive viscosity and thermal
+conductivity in damping of the slow waves in coronal loops with and without
+heating cooling imbalance. We have analyzed wave damping for the range of loop
+length $L$=50-500 Mm, temperature $T$=5-30 MK, and density
+$\rho$=10$^{-11}$-10$^{-9}$ kg m$^{-3}$. It was found that inclusion of
+compressive viscosity along with thermal conductivity significantly enhances
+the damping of fundamental mode oscillations in shorter (e.g., $L$=50 Mm) and
+super-hot ($T>$10 MK) loops. However, role of the viscosity in damping is
+insignificant in longer (e.g., $L$=500 Mm) and hot loops (T$\leq$10 MK) where,
+instead, thermal conductivity along with the presence of heating cooling
+imbalance plays a dominant role. For the shorter loops at the super-hot regime
+of the temperature, increment in loop density substantially enhances damping of
+the fundamental modes due to thermal conductivity when the viscosity is absent,
+however, when the compressive viscosity is added the increase in density
+substantially weakens damping. Thermal conductivity alone is found to play a
+dominant role in longer loops at lower temperatures (T$\leq$10 MK), while
+compressive viscosity dominates in damping at super-hot temperatures ($T>$10
+MK) in shorter loops. The predicted scaling law between damping time ($\tau$)
+and wave period ($P$) is found to better match to observed SUMER oscillations
+when heating cooling imbalance is taken into account in addition to thermal
+conductivity and compressive viscosity for the damping of the fundamental slow
+mode oscillations.",2011.14519v2
+1999-08-20,The ac-Driven Motion of Dislocations in a Weakly Damped Frenkel-Kontorova Lattice,"By means of numerical simulations, we demonstrate that ac field can support
+stably moving collective nonlinear excitations in the form of dislocations
+(topological solitons, or kinks) in the Frenkel-Kontorova (FK) lattice with
+weak friction, which was qualitatively predicted by Bonilla and Malomed [Phys.
+Rev. B{\bf 43}, 11539 (1991)]. Direct generation of the moving dislocations
+turns out to be virtually impossible; however, they can be generated initially
+in the lattice subject to an auxiliary spatial modulation of the on-site
+potential strength. Gradually relaxing the modulation, we are able to get the
+stable moving dislocations in the uniform FK lattice with the periodic boundary
+conditions, provided that the driving frequency is close to the gap frequency
+of the linear excitations in the uniform lattice. The excitations have a large
+and noninteger index of commensurability with the lattice (suggesting that its
+actual value is irrational). The simulations reveal two different types of the
+moving dislocations: broad ones, that extend, roughly, to half the full length
+of the periodic lattice (in that sense, they cannot be called solitons), and
+localized soliton-like dislocations, that can be found in an excited state,
+demonstrating strong persistent internal vibrations. The minimum (threshold)
+amplitude of the driving force necessary to support the traveling excitation is
+found as a function of the friction coefficient. Its extrapolation suggests
+that the threshold does not vanish at the zero friction, which may be explained
+by radiation losses. The moving dislocation can be observed experimentally in
+an array of coupled small Josephson junctions in the form of an {\it inverse
+Josephson effect}, i.e., a dc-voltage response to the uniformly applied ac bias
+current.",9908292v1
+2003-06-19,Quantum model of phonon transport and heat conductivity in carbon nanoclusters and nanotubes,"A complex approach phonon quantum discrete model (PQDM) was developed to
+describe dynamics, kinetics and statistics of phonons in carbon nanostructures
+with zero-chirality of both zig-zag and armchair geometry. The model allows
+include into the pure phonon problem existing interaction with others
+subsystems: electrons, photons, impurities and defects. We predict that planar
+C- structures are geometrically stable and may bridge interelectrode space in
+strong external electric field. The exact solution of generalized thermal
+conductivity (TC) equation was obtained for nanotubes. Temperature distribution
+along the tube was derived analytically. The diagonalization procedure for the
+case ofstrong ph-ph interaction was proposed. It was shown the quadratic
+increasing of heat conductivity with the growth of the phonon mean free path
+(PMFP). Heat capacitance and the entropy of carbon linear tubes were calculated
+as the function of temperature. Our theoretical approach explains the nature of
+good TC in carbon and carbon-like materials by existing of the soft vibration
+branch (low frequency radial breathing mode phonons with high density of states
+at thermal energies) accompanied by structure hardness (high frequency $\phi$-
+and z-branches) providing big PMFP. TC coefficient for high conducting channel
+in surrounding medium was calculated. The mechanism of heat conductivity
+temperature damping was analyzed. Two competitive tendencies produce TC maximum
+at intermediate temperatures (100-300)K. It was shown the strongly non-linear
+increasing of effective heat conductivity with the growth nanotubes
+concentration. It was shown that insertion of armchair nanotube inside a medium
+or its coating by polyacetilene molecule considerably changes the structure of
+radial breathing phonons.",0306503v1
+2005-02-11,A Weakly Nonlinear Analysis of Impulsively-Forced Faraday Waves,"Parametrically-excited surface waves, forced by a periodic sequence of
+delta-function impulses, are considered within the framework of the
+Zhang-Vi\~nals model (J. Fluid Mech. 1997). The exact impulsive-forcing
+results, in the linear and weakly nonlinear regimes, are compared with
+numerical results for sinusoidal and multifrequency forcing. We find
+surprisingly good agreement between impulsive forcing results and those
+obtained using a two-term truncated Fourier series representation of the
+impulsive forcing function. As noted previously by Bechhoefer and Johnson (Am.
+J. Phys. 1996), in the case of two equally-spaced impulses per period there are
+only subharmonic modes of instability. The familiar situation of alternating
+subharmonic and harmonic resonance tongues emerges for unequally-spaced
+impulses. We extend the linear analysis for two impulses per period to the
+weakly nonlinear regime for one-dimensional waves. Specifically, we derive an
+analytic expression for the cubic Landau coefficient in the bifurcation
+equation as a function of the dimensionless fluid parameters and spacing
+between the two impulses. As the capillary parameter is varied, one finds a
+parameter region of wave amplitude suppression, which is due to a familiar 1:2
+spatio-temporal resonance between the subharmonic mode of instability and a
+damped harmonic mode. This resonance occurs for impulsive forcing even when
+harmonic resonance tongues are absent from the neutral stability curve. The
+strength of this resonance feature can be tuned by varying the spacing between
+the impulses. This finding is interpreted in terms of a recent symmetry-based
+analysis of multifrequency forced Faraday waves by Porter, Topaz and Silber
+(Phys. Rev. Lett. 2004, Phys. Rev. E 2004).",0502025v1
+2007-06-25,Toward faithful templates for non-spinning binary black holes using the effective-one-body approach,"We present an accurate approximation of the full gravitational radiation
+waveforms generated in the merger of non-eccentric systems of two non-spinning
+black holes. Utilizing information from recent numerical relativity simulations
+and the natural flexibility of the effective-one-body (EOB) model, we extend
+the latter so that it can successfully match the numerical relativity waveforms
+during the last stages of inspiral, merger and ringdown. By ``successfully''
+here, we mean with phase differences < 8% of a gravitational-wave cycle
+accumulated by the end of the ringdown phase, maximizing only over time of
+arrival and initial phase. We obtain this result by simply adding a
+4-post-Newtonian order correction in the EOB radial potential and determining
+the (constant) coefficient by imposing high-matching performances with
+numerical waveforms of mass ratios m1/m2 = 1, 3/2, 2 and 4, m1 and m2 being the
+individual black-hole masses. The final black-hole mass and spin predicted by
+the numerical simulations are used to determine the ringdown frequency and
+decay time of three quasi-normal-mode damped sinusoids that are attached to the
+EOB inspiral-(plunge) waveform at the EOB light-ring. The EOB waveforms might
+be tested and further improved in the future by comparison with extremely long
+and accurate inspiral numerical-relativity waveforms. They may already be
+employed for coherent searches and parameter estimation of gravitational waves
+emitted by non-spinning coalescing binary black holes with ground-based
+laser-interferometer detectors.",0706.3732v3
+2011-08-21,Time-Dependent Behavior of Lyman$α$ Photon Transfer in High Redshift Optically Thick Medium,"With Monte Carlo simulation method, we investigate the time dependent
+behavior of Ly$\alpha$ photon transfer in optically thick medium of the
+concordance $\Lambda$CDM universe. At high redshift, the Ly$\alpha$ photon
+escaping from optically thick medium has a time scale as long as the age of the
+luminous object, or even comparable to the age of the universe. In this case,
+time-independent, or stationary solutions of the Ly$\alpha$ photon transfer
+with resonant scattering will overlook important features of the escaped
+Ly$\alpha$ photons in physical and frequency spaces. More seriously, the
+expansion of the universe leads to that the time-independent solutions of the
+Ly$\alpha$ photon transfer may not exist. We show that time-dependent solutions
+sometimes are essential for understanding the Ly$\alpha$ emission and
+absorption at high redshifts. For Ly\alpha photons from sources at redshift
+1+z=10 and being surrounded by neutral hydrogen IGM of the $\Lambda$CDM
+universe, the escape coefficient is found to be always less, or much less than
+one, regardless of the age or life time of the sources. Under such environment,
+we also find that even when the Ly$\alpha$ photon luminosity of the sources is
+stable, the mean surface brightness is gradually increasing in the first 10^6
+years, and then decreasing with a power law of time, but never approaches a
+stable, time-independent state. That is, all 1+z=10 sources in a neutral Hubble
+expanding IGM with Ly$\alpha$ luminosity L have their maximum of mean surface
+brightness ~ 10^{-21}(L/(10^{43}erg/s)) erg s^{-1} cm^{-2} arcsec^{-2} at the
+age of about 10^6 years. The time-dependent effects on the red damping wing
+profile are also addressed.",1108.4162v1
+2011-09-03,Magnetic Fields Effects on the Electronic Conduction Properties of Molecular Ring Structures,"While mesoscopic conducting loops are sensitive to external magnetic fields,
+as seen by observations of the Aharonov-Bohm (AB) effect in such structures,
+the field needed to observe the AB periodicity in small molecular rings is
+unrealistically large. The present study aims to identify conditions under
+which magnetic field dependence can be observed in electronic conduction
+through such molecules. We consider molecular ring structures modeled both
+within the tight-binding (H\""uckel) model and as continuous rings. In fact,
+much of the observed qualitative behavior can be rationalized in terms of a
+much simpler two-state model. Dephasing in these models is affected by two
+common tools: the B\""uttiker probe method and coherence damping within a
+density matrix formulation. We show that current through a benzene ring can be
+controlled by moderate fields provided that (a) conduction must be dominated by
+degenerate (in the free molecule) molecular electronic resonances, associated
+with multiple pathways as is often the case with ring molecules; (b)
+molecular-leads electronic coupling must is weak so as to affect relatively
+distinct conduction resonances; (c) molecular binding to the leads must be
+asymmetric (e.g., for benzene, connection in the meta or ortho, but not para,
+configurations) and, (d) dephasing has to be small. Under these conditions,
+considerable sensitivity to an imposed magnetic field normal to the molecular
+ring plane is found in benzene and other aromatic molecules. Interestingly, in
+symmetric junctions (e.g. para connected benzene) a large sensitivity of the
+transmission coefficient to magnetic field is not reflected in the
+current-voltage characteristic. Although sensitivity to magnetic field is
+suppressed by dephasing, quantitative estimates indicate that magnetic field
+control can be observed under realistic condition.",1109.0619v1
+2012-04-01,Resonance Broadening and Heating of Charged Particles in Magnetohydrodynamic Turbulence,"The heating, acceleration, and pitch-angle scattering of charged particles by
+MHD turbulence are important in a wide range of astrophysical environments,
+including the solar wind, accreting black holes, and galaxy clusters. We
+simulate the interaction of high-gyrofrequency test particles with fully
+dynamical simulations of subsonic MHD turbulence, focusing on the parameter
+regime with beta ~ 1, where beta is the ratio of gas to magnetic pressure. We
+use the simulation results to calibrate analytical expressions for test
+particle velocity-space diffusion coefficients and provide simple fits that can
+be used in other work.
+  The test particle velocity diffusion in our simulations is due to a
+combination of two processes: interactions between particles and magnetic
+compressions in the turbulence (as in linear transit-time damping; TTD) and
+what we refer to as Fermi Type-B (FTB) interactions, in which charged particles
+moving on field lines may be thought of as beads spiralling around moving
+wires. We show that test particle heating rates are consistent with a TTD
+resonance which is broadened according to a decorrelation prescription that is
+Gaussian in time. TTD dominates the heating for v_s >> v_A (e.g. electrons),
+where v_s is the thermal speed of species s and v_A is the Alfven speed, while
+FTB dominates for v_s << v_A (e.g. minor ions). Proton heating rates for beta ~
+1 are comparable to the turbulent cascade rate. Finally, we show that velocity
+diffusion of collisionless, large gyrofrequency particles due to large-scale
+MHD turbulence does not produce a power-law distribution function.",1204.0155v2
+2012-07-18,Quasinormal-mode spectrum of Kerr black holes and its geometric interpretation,"There is a well-known, intuitive geometric correspondence between
+high-frequency QNMs of Schwarzschild black holes and null geodesics that reside
+on the light-ring : the real part of the mode's frequency relates to the
+geodesic's orbital frequency, and the imaginary part of the frequency
+corresponds to the Lyapunov exponent of the orbit. For slowly rotating black
+holes, the QNM real frequency is a linear combination of a the orbit's
+precessional and orbital frequencies, but the correspondence is otherwise
+unchanged. In this paper, we find a relationship between the QNM frequencies of
+Kerr black holes of arbitrary (astrophysical) spins and general spherical
+photon orbits, which is analogous to the relationship for slowly rotating
+holes. To derive this result, we first use the WKB approximation to compute
+accurate algebraic expressions for large-l QNM frequencies. Comparing our WKB
+calculation to the leading-order, geometric-optics approximation to scalar-wave
+propagation in the Kerr spacetime, we then draw a correspondence between the
+real parts of the parameters of a QNM and the conserved quantities of spherical
+photon orbits. At next-to-leading order in this comparison, we relate the
+imaginary parts of the QNM parameters to coefficients that modify the amplitude
+of the scalar wave. With this correspondence, we find a geometric
+interpretation to two features of the QNM spectrum of Kerr black holes: First,
+for Kerr holes rotating near the maximal rate, a large number of modes have
+nearly zero damping; we connect this characteristic to the fact that a large
+number of spherical photon orbits approach the horizon in this limit. Second,
+for black holes of any spins, the frequencies of specific sets of modes are
+degenerate; we find that this feature arises when the spherical photon orbits
+corresponding to these modes form closed (as opposed to ergodically winding)
+curves.",1207.4253v1
+2013-03-18,Sensitivity analysis of a time-delayed thermo-acoustic system via an adjoint-based approach,"We apply adjoint-based sensitivity analysis to a time-delayed thermo-acoustic
+system: a Rijke tube containing a hot wire. We calculate how the growth rate
+and frequency of small oscillations about a base state are affected either by a
+generic passive control element in the system (the structural sensitivity
+analysis) or by a generic change to its base state (the base-state sensitivity
+analysis). We illustrate the structural sensitivity by calculating the effect
+of a second hot wire with a small heat release parameter. In a single
+calculation, this shows how the second hot wire changes the growth rate and
+frequency of the small oscillations, as a function of its position in the tube.
+We then examine the components of the structural sensitivity in order to
+determine the passive control mechanism that has the strongest influence on the
+growth rate. We find that a force applied to the acoustic momentum equation in
+the opposite direction to the instantaneous velocity is the most stabilizing
+feedback mechanism. We also find that its effect is maximized when it is placed
+at the downstream end of the tube. This feedback mechanism could be supplied,
+for example, by an adiabatic mesh. We illustrate the base-state sensitivity by
+calculating the effects of small variations in the damping factor, the
+heat-release time-delay coefficient, the heat-release parameter, and the hot
+wire location. The successful application of sensitivity analysis to
+thermo-acoustics opens up new possibilities for the passive control of
+thermo-acoustic oscillations by providing gradient information that can be
+combined with constrained optimization algorithms in order to reduce linear
+growth rates.",1303.4267v2
+2013-07-12,Detection of Lyβauto-correlations and Lyα-Lyβ cross-correlations in BOSS Data Release 9,"The Lyman-$\beta$ forest refers to a region in the spectra of distant quasars
+that lies between the rest-frame Lyman-$\beta$ and Lyman-$\gamma$ emissions.
+The forest in this region is dominated by a combination of absorption due to
+resonant Ly$\alpha$ and Ly$\beta$ scattering. When considering the 1D Ly$\beta$
+forest in addition to the 1D Ly$\alpha$ forest, the full statistical
+description of the data requires four 1D power spectra: Ly$\alpha$ and
+Ly$\beta$ auto-power spectra and the Ly$\alpha$-Ly$\beta$ real and imaginary
+cross-power spectra. We describe how these can be measured using an optimal
+quadratic estimator that naturally disentangles Ly$\alpha$ and Ly$\beta$
+contributions. Using a sample of approximately 60,000 quasar sight-lines from
+the BOSS Data Release 9, we make the measurement of the one-dimensional power
+spectrum of fluctuations due to the Ly$\beta$ resonant scattering. While we
+have not corrected our measurements for resolution damping of the power and
+other systematic effects carefully enough to use them for cosmological
+constraints, we can robustly conclude the following: i) Ly$\beta$ power
+spectrum and Ly$\alpha$-Ly$\beta$ cross spectra are detected with high
+statistical significance; ii) the cross-correlation coefficient is $\approx 1$
+on large scales; iii) the Ly$\beta$ measurements are contaminated by the
+associated OVI absorption, which is analogous to the SiIII contamination of the
+Ly$\alpha$ forest. Measurements of the Ly$\beta$ forest will allow extension of
+the usable path-length for the Ly$\alpha$ measurements while allowing a better
+understanding of the physics of intergalactic medium and thus more robust
+cosmological constraints.",1307.3403v4
+2013-12-20,Stability Boundaries for Resonant Migrating Planet Pairs,"Convergent migration allows pairs of planet to become trapped into mean
+motion resonances. Once in resonance, the planets' eccentricities grow to an
+equilibrium value that depends on the ratio of migration time scale to the
+eccentricity damping timescale, $K=\tau_a/\tau_e$, with higher values of
+equilibrium eccentricity for lower values of $K$. For low equilibrium
+eccentricities, $e_{eq}\propto K^{-1/2}$. The stability of a planet pair
+depends on eccentricity so the system can become unstable before it reaches its
+equilibrium eccentricity. Using a resonant overlap criterion that takes into
+account the role of first and second order resonances and depends on
+eccentricity, we find a function $K_{min}(\mu_p, j)$ that defines the lowest
+value for $K$, as a function of the ratio of total planet mass to stellar mass
+($\mu_p$) and the period ratio of the resonance defined as $P_1/P_2=j/(j+k)$,
+that allows two convergently migrating planets to remain stable in resonance at
+their equilibrium eccentricities. We scaled the functions $K_{min}$ for each
+resonance of the same order into a single function $K_c$. The function $K_{c}$
+for planet pairs in first order resonances is linear with increasing planet
+mass and quadratic for pairs in second order resonances with a coefficient
+depending on the relative migration rate and strongly on the planet to planet
+mass ratio. The linear relation continues until the mass approaches a critical
+mass defined by the 2/7 resonance overlap instability law and $K_c \to \infty$.
+We compared our analytic boundary with an observed sample of resonant two
+planet systems. All but one of the first order resonant planet pair systems
+found by radial velocity measurements are well inside the stability region
+estimated by this model. We calculated $K_c$ for Kepler systems without
+well-constrained eccentricities and found only weak constraints on $K$.",1312.6099v1
+2014-04-10,Electromagnetic effects in the pion dispersion relation at finite temperature,"We investigate the charged-neutral pion self-energy difference at finite
+temperature. Within Chiral Perturbation Theory we extend previous analysis in
+the chiral and soft pion limits. Our analysis with physical masses leads to
+additional contributions for temperatures typical of a meson gas, including a
+momentum-dependent function for the self energy. In addition, a nonzero
+imaginary part arises, which we define consistently in the Coulomb gauge and
+comes from an infrared enhanced contribution due to thermal bath photons. For
+distributions typical of a heavy-ion meson gas, the charged and neutral pion
+masses and their difference depend on temperature through slowly increasing
+functions. Chiral symmetry restoration is ultimately responsible for keeping
+the corrections smooth and compatible with observed pion spectra. We study
+phenomenological effects related to the electromagnetic damping leading to
+corrections for transport coefficients and neutral-charged mean free times
+differences. An important aspect is the connection with chiral symmetry
+restoration through the relation of the pion mass difference with the
+vector-axial spectral function difference, which holds at $T=0$ due to a sum
+rule in the chiral and soft pion limits. We analyze the modifications of that
+sum rule including nonzero pion masses and temperature, up to order $T^2$ and
+$M_\pi^2$. Both effects produce terms making the pion mass difference grow
+against chiral-restoring decreasing contributions. Finally, we analyze the
+corrections to the previous ChPT and sum rule results within the resonance
+saturation framework at finite temperature, including explicitly $\rho$ and
+$a_1$ exchanges. Our results show that the ChPT result is robust at low and
+intermediate temperatures, the leading corrections being of order $T^2
+M_\pi^2/M_R^2$ with $M_R$ the involved resonance masses.",1404.2746v3
+2014-11-10,Nonlinear Dynamics of Particles Excited by an Electric Curtain,"The use of the electric curtain (EC) has been proposed for manipulation and
+control of particles in various applications. The EC studied in this paper is
+called the 2-phase EC, which consists of a series of long parallel electrodes
+embedded in a thin dielectric surface. The EC is driven by an oscillating
+electric potential of a sinusoidal form where the phase difference of the
+electric potential between neighboring electrodes is 180 degrees. We
+investigate the one- and two-dimensional nonlinear dynamics of a particle in an
+EC field. The form of the dimensionless equations of motion is codimension two,
+where the dimensionless control parameters are the interaction amplitude ($A$)
+and damping coefficient ($\beta$). Our focus on the one-dimensional EC is
+primarily on a case of fixed $\beta$ and relatively small $A$, which is
+characteristic of typical experimental conditions. We study the nonlinear
+behaviors of the one-dimensional EC through the analysis of bifurcations of
+fixed points. We analyze these bifurcations by using Floquet theory to
+determine the stability of the limit cycles associated with the fixed points in
+the Poincar\'e sections. Some of the bifurcations lead to chaotic trajectories
+where we then determine the strength of chaos in phase space by calculating the
+largest Lyapunov exponent. In the study of the two-dimensional EC we
+independently look at bifurcation diagrams of variations in $A$ with fixed
+$\beta$ and variations in $\beta$ with fixed $A$. Under certain values of
+$\beta$ and $A$, we find that no stable trajectories above the surface exists;
+such chaotic trajectories are described by a chaotic attractor, for which the
+the largest Lyapunov exponent is found. We show the well-known stable
+oscillations between two electrodes come into existence for variations in $A$
+and the transitions between several distinct regimes of stable motion for
+variations in $\beta$.",1411.2492v1
+2015-04-20,On the Riesz basis property of root vectors system for $2 \times 2$ Dirac type operators,"The paper is concerned with the Riesz basis property of a boundary value
+problem associated in $L^2[0,1] \otimes \mathbb{C}^2$ with the following $2
+\times 2$ Dirac type equation $$ L y = -i B^{-1} y' + Q(x) y = \lambda y, \quad
+B = \begin{pmatrix} b_1 & 0 \\ 0 & b_2 \end{pmatrix}, \quad y = \begin{pmatrix}
+y_1 \\ y_2 \end{pmatrix}, \quad (1) $$ with a summable potential matrix $Q \in
+L^1[0,1] \otimes \mathbb{C}^{2 \times 2}$ and $b_1 < 0 < b_2$. If $b_2 = -b_1
+=1$ this equation is equivalent to one dimensional Dirac equation. It is proved
+that the system of root functions of a linear boundary value problem
+constitutes a Riesz basis in $L^2[0,1] \otimes \mathbb{C}^2$ provided that the
+boundary conditions are strictly regular.
+  By analogy with the case of ordinary differential equations, boundary
+conditions are called strictly regular if the eigenvalues of the corresponding
+unperturbed $(Q=0)$ operator are asymptotically simple and separated. As
+distinguished from the Dirac case there is no simple algebraic criterion of the
+strict regularity whenever $b_1 + b_2 \not = 0$. However under certain
+restrictions on coefficients of the boundary linear forms we present certain
+algebraic criteria of the strict regularity in the latter case. In particular,
+it is shown that regular separated boundary conditions are always strictly
+regular while periodic (antiperiodic) boundary conditions are strictly regular
+if and only if $b_1 + b_2 \not = 0.$
+  The proof of the main result is based on existence of triangular
+transformation operators for system (1). Their existence is also established
+here in the case of a summable $Q$. In the case of regular (but not strictly
+regular) boundary conditions we prove the Riesz basis property with
+parentheses. The main results are applied to establish the Riesz basis property
+of the dynamic generator of spatially non-homogenous damped Timoshenko beam
+model.",1504.04954v2
+2015-10-14,Fermi surface versus Fermi sea contributions to intrinsic anomalous and spin Hall effects of multiorbital metals in the presence of Coulomb interaction and spin-Coulomb drag,"Anomalous Hall effect (AHE) and spin Hall effect (SHE) are fundamental
+phenomena, and their potential for application is great. However, we understand
+the interaction effects unsatisfactorily, and should have clarified issues
+about the roles of the Fermi sea term and Fermi surface term of the
+conductivity of the intrinsic AHE or SHE of an interacting multiorbital metal
+and about the effects of spin-Coulomb drag on the intrinsic SHE. Here we
+resolve the first issue and provide the first step about the second issue by
+developing a general formalism in the linear response theory with appropriate
+approximations and using analytic arguments. The most striking result is that
+even without impurities the Fermi surface term, a non-Berry-curvature term,
+plays dominant roles at high or slightly low temperatures. In particular, this
+Fermi surface term causes the temperature dependence of the dc anomalous Hall
+or spin Hall conductivity due to the interaction-induced quasiparticle damping
+and the correction of the dc spin Hall conductivity due to the spin-Coulomb
+drag. Those results revise our understanding of the intrinsic AHE and SHE. We
+also find that the differences between the dc anomalous Hall and longitudinal
+conductivities arise from the difference in the dominant multiband excitations.
+This not only explains why the Fermi sea term such as the Berry-curvature term
+becomes important in clean and low-temperature case only for interband
+transports but also provides the useful principles on treating the
+electron-electron interaction in an interacting multiorbital metal for general
+formalism of transport coefficients. Several correspondences between our
+results and experiments are finally discussed.",1510.03988v5
+2016-05-02,Cosmic Galaxy-IGM HI Relation at ${\it{z}}\sim 2-3$ Probed in the COSMOS/UltraVISTA $1.6$ deg$^2$ Field,"We present spatial correlations of galaxies and IGM HI in the
+COSMOS/UltraVISTA 1.62 deg$^2$ field. Our data consist of 13,415 photo-$z$
+galaxies at $z\sim2-3$ with $K_s<23.4$ and the Ly$\alpha$ forest absorptions in
+the background quasar spectra selected from SDSS data with no signature of
+damped Ly$\alpha$ system contamination. We estimate a galaxy overdensity
+$\delta_{gal}$ in an impact parameter of 2.5 pMpc, and calculate the Ly$\alpha$
+forest fluctuations $\delta_{\langle F\rangle}$ whose negative values
+correspond to the strong Ly$\alpha$ forest absorptions. We identify weak
+evidence of an anti-correlation between $\delta_{gal}$ and $\delta_{\langle
+F\rangle}$ with a Spearman's rank correlation coefficient of $-0.39$ suggesting
+that the galaxy overdensities and the Ly$\alpha$ forest absorptions positively
+correlate in space at the $\sim90\%$ confidence level. This positive
+correlation indicates that high-$z$ galaxies exist around an excess of HI gas
+in the Ly$\alpha$ forest. We find four cosmic volumes, dubbed
+$A_{obs}$-$D_{obs}$, that have extremely large (small) values of $\delta_{gal}
+\simeq0.8$ ($-1$) and $\delta_{\langle F\rangle}$ $\simeq0.1$ ($-0.4$), three
+out of which, $B_{obs}$-$D_{obs}$, significantly depart from the correlation,
+and weaken the correlation signal. We perform cosmological hydrodynamical
+simulations, and compare with our observational results. Our simulations
+reproduce the correlation, agreeing with the observational results. Moreover,
+our simulations have model counterparts of $A_{obs}$-$D_{obs}$, and suggest
+that the observations pinpoint, by chance, a galaxy overdensity like a
+proto-cluster, gas filaments lying on the sightline, a large void, and
+orthogonal low-density filaments. Our simulations indicate that the significant
+departures of $B_{obs}$-$D_{obs}$ are produced by the filamentary large-scale
+structures and the observation sightline effects.",1605.00379v3
+2016-10-19,New scenario of turbulence theory and wall-bounded turbulence: Theoretical significance,"General scenario of turbulence theory is proposed and applied to streaky
+wall-bounded turbulence. This scenario introduces a new field of transverse
+waves. Significance of the theory rests on a mathematical theorem associated
+with the conservation law of current flux, expressed in a form of 4d physical
+space-time representation, which predicts a system of Maxwell-type equation and
+supports transverse waves traveling with a phase speed c_t. In regard to the
+streaky wall flows, there exist both dynamical mechanism and energy channel
+which excite transverse waves and exchange energy between flow field and wave
+field. Energy is supplied from the flow field to the wave field if wavelengths
+are sufficiently large. The waves are accompanied with a new mechanism of
+energy dissipation, an internal friction analogous to the Ohm's effect. Some
+part of the energy is dissipated into heat. Thus, there exists a sustaining
+mechanism, which implies that the streaky structure of wall-bounded turbulence
+is a dissipative structure.
+  The predictions are consistent with experimental observations of wall
+turbulence: (i) Existence of traveling waves: The waves are characterized by
+two scales of wavelength and a damping-length d. (ii) Existence of two large
+scales (LSM and VLSM) observed in turbulent shear flows: Those are interpreted
+by the waves amplified with the transient growth mechanism and maintained by
+interaction with the new transverse wave field. The waves are robust since they
+have their own energy and momentum. (iii) Enhanced energy dissipation in wavy
+turbulence. Its bulk rate of energy dissipation takes a form resembling the
+models of eddy-viscosity, and its coefficient \nu_D is estimated to be of the
+order of c_t d and much larger than the molecular viscosity.
+  No self-contradiction is incurred by the new field introduced.",1610.05975v2
+2016-11-22,The cross-correlation between 21cm intensity mapping maps and the Lyman-alpha forest in the post-reionization era,"We investigate the cross-correlation signal between 21cm intensity mapping
+maps and the Lyman-alpha forest in the fully non-linear regime using
+state-of-the-art hydrodynamic simulations. The cross-correlation signal between
+these fields can provide a coherent and comprehensive picture of the neutral
+hydrogen (HI) content of our Universe in the post-reionization era, probing
+both its mass content and volume distribution. We compute the auto-power
+spectra of both fields together with their cross-power spectrum at z = 2.4 and
+find that on large scales the fields are completely anti-correlated. This
+anti-correlation arises because regions with high (low) 21cm emission, such as
+those with a large (low) concentration of damped Lyman-alpha systems, will show
+up as regions with low (high) transmitted flux. We find that on scales smaller
+than k = 0.2 h/Mpc the cross-correlation coefficient departs from -1, at a
+scale where non-linearities show up. We use the anisotropy of the power spectra
+in redshift-space to determine the values of the bias and of the redshift-space
+distortion parameters of both fields; we find that the errors on the value of
+these parameters could decrease by 30% when adding data from the cross-power
+spectrum in a conservative analysis. Our results point out that linear theory
+is capable of reproducing the shape and amplitude of the cross-power up to
+rather non-linear scales. Finally, we find that the 21cm-Lya cross-power
+spectrum can be detected by combining data from a BOSS-like survey together
+with 21cm intensity mapping observations by SKA1-MID with a S/N ratio higher
+than 3 in the range 0.06< k <1 h/Mpc. We emphasize that while the shape and
+amplitude of the 21cm auto-power spectrum can be severely affected by residual
+foreground contamination, cross-power spectra will be less sensitive to that
+and therefore can be used to identify systematics in the 21cm maps.",1611.07527v2
+2017-02-02,Bouncing on Titan: Motion of the Huygens Probe in the Seconds After Landing,"While landing on Titan, several instruments onboard Huygens acquired
+measurements that indicate the probe did not immediately come to rest. Detailed
+knowledge of the probe's motion can provide insight into the nature of Titan's
+surface. Combining accelerometer data from the Huygens Atmospheric Structure
+Instrument (HASI) and the Surface Science Package (SSP) with photometry data
+from the Descent Imager/Spectral Radiometer (DISR) we develop a quantitative
+model to describe motion of the probe, and its interaction with the surface.
+The most likely scenario is the following. Upon impact, Huygens created a 12 cm
+deep hole in the surface of Titan. It bounced back, out of the hole onto the
+flat surface, after which it commenced a 30-40 cm long slide in the southward
+direction. The slide ended with the probe out of balance, tilted in the
+direction of DISR by around 10 degrees. The probe then wobbled back and forth
+five times in the north-south direction, during which it probably encountered a
+1-2 cm sized pebble. The SSP provides evidence for movement up to 10 s after
+impact. This scenario puts the following constraints on the physical properties
+of the surface. For the slide over the surface we determine a friction
+coefficient of 0.4. While this value is not necessarily representative for the
+surface itself due to the presence of protruding structures on the bottom of
+the probe, the dynamics appear to be consistent with a surface consistency of
+damp sand. Additionally, we find that spectral changes observed in the first
+four seconds after landing are consistent with a transient dust cloud, created
+by the impact of the turbulent wake behind the probe on the surface. The
+optical properties of the dust particles are consistent with those of Titan
+aerosols from Tomasko et al. (P&SS 56, 669). We suggest that the surface at the
+landing site was covered by a dust layer, possibly the 7 mm layer of...",1702.00667v1
+2017-06-26,"Parsing spatiotemporal dynamical stability in ECoG during seizure onset, propagation, and termination","Understanding brain dynamics in epilepsy is critical for establishing
+rigorous control objectives that enable new therapeutic methods to mitigate
+seizure occurrence. In multichannel electrocorticography (ECoG) recordings
+acquired in 21 subjects during a total of 94 seizures, we apply dynamical
+systems stability analysis to assess the balance versus imbalance of seizure
+dynamics across different timescales and brain regions. Specifically, we
+consider a sliding time window multivariate autoregressive linear approximation
+of the data captured by the ECoG channels, where eigendecomposition of the
+estimated matrix of coefficients describes the contribution of different
+regions to the spatiotemporal process (eigenvectors) associated with a
+particular timescale (eigenvalues). Interestingly, we observe a pattern of
+eigenvalue evolution and slowly changing (or approximately time-invariant)
+eigenvectors across both seizures and subjects. The seizure-onset is marked by
+an increase in high frequency spatial information to which a few regions
+contribute for a long period. By contrast, the seizure termination is
+characterized by a sudden, small time period change in dynamics to which many
+regions contribute. As the seizure terminates, the relatively stable ictal
+dynamics rapidly transition into the post-ictal regime, marked by relatively
+fast-damping oscillations. Our methodology offers a subject-specific
+characterization of the spatiotemporal behavior of the seizure, providing new
+insights into the dynamic patterns and functional interactions between brain
+regions that occur over different timescales. More generally, our approach
+informs the development of engineering objectives that can be used to deploy
+new control strategies to prevent seizure evolution or to hasten seizure
+termination.",1706.08202v1
+2017-10-05,Cross section alignment of polycyclic aromatic hydrocarbons by anisotropic radiation,"We study the effect of anisotropic radiation illumination on the alignment of
+polycyclic aromatic hydrocarbons (PAHs) and report that cross-sectional
+mechanism of alignment earlier considered in terms of gas-grain interactions
+can also be efficient for the photon-grain interaction. We demonstrate this by
+first calculating the angle-dependence rotational damping and excitation
+coefficients by photon absorption followed by infrared emission. We then
+calculate the degree of PAH alignment for the different environments and
+physical parameters, including the illumination direction, ionization fraction,
+and magnetic field strength. For the reflection nebula (RN) conditions with
+unidirectional radiation field, we find that the degree of alignment tends to
+increase with increasing the angle $\psi$ between the illumination direction
+and the magnetic field, as a result of the decrease of the cross-section of
+photon absorption with $\psi$. We calculate the polarization of spinning PAH
+emission using the obtained degree of alignment for the different physical
+parameters, assuming constant grain temperatures. We find that the polarization
+of spinning PAH emission from RN can be large, between $5-20~\%$ at frequencies
+$\nu > 20$ GHz, whereas the polarization is less than $3~\%$ for
+photodissociation regions (PDRs). In realistic conditions, the polarization is
+expected to be lower due to grain temperature fluctuations and magnetic field
+geometry. The polarization for the diffuse cold neutral medium (CNM) is rather
+low, below $1~\%$ at $\nu>20$ GHz, consistent with observations by WMAP and
+Planck. Our results demonstrate that the RNe are the favored environment to
+observe the polarization of spinning dust emission as well as polarized mid-IR
+emission from PAHs.",1710.01835v2
+2018-06-01,Kinetic Model for Stochastic Heating in the INCA Discharge,"A novel electron heating mechanism based on periodically structured vortex
+fields induced in a plane was first proposed in 2014 [U. Czarnetzki and Kh.
+Tarnev, Physics of Plasmas 21, 123508 (2014)]. This theoretical concept has now
+been realized in an experiment which confirms efficient collisionless heating
+in such array structures [Ph. Ahr, T.V. Tsankov, J. Kuhfeld, U. Czarnetzki,
+submitted to Plasma Sources Science and Technology, arXiv:1806.02043v1 (2018)].
+The new concept is called ""Inductively Coupled Array"": INCA. Here, the physical
+mechanism behind the collisionless (stochastic) heating is investigated by two
+analytical models. Firstly, the electron heating rate in an array field
+structure with an exponential spatial decay of the field in the direction
+perpendicular to the plane is investigated by stochastically averaging single
+electron trajectories. The approach is similar to the Lieberman model for the
+classical stochastic heating in standard inductively coupled plasmas. This
+analysis shows that classical stochastic heating by thermal motion along the
+vertical direction makes a negligible contribution. However, there is a strong
+collisonless non-local heating effect in the plane. In conclusion, heating is
+non-local in the plane but local in the vertical direction. This insight allows
+a straightforward solution of the collisionless Boltzmann equation which not
+only confirms the results of the Lieberman model but provides also explicit
+expressions for the complex conductivity. Based on the conductivity an
+effective stochastic collision frequency, the complex damping coefficient and
+the related field penetration of the field into the plasma is calculated.
+Finally, elastic collisions with neutral background atoms are included in the
+model and a condition for dominance of stochastic heating over Ohmic heating is
+derived.",1806.00505v2
+2019-01-09,Wave heating in gravitationally stratified coronal loops in the presence of resistivity and viscosity,"In recent years, coronal loops have been the focus of studies related to the
+damping of different magnetohydrodynamic (MHD) surface waves and their
+connection with coronal seismology and wave heating. For a better understanding
+of wave heating, we need to take into account the effects of different
+dissipation coefficients such as resistivity and viscosity, the importance of
+the loop physical characteristics, and the ways gravity can factor into the
+evolution of these phenomena. We aim to map the sites of energy dissipation
+from transverse waves in coronal loops in the presence and absence of
+gravitational stratification and to compare ideal, resistive, and viscous MHD.
+Using the PLUTO code, we performed 3D MHD simulations of kink waves in single,
+straight, density-enhanced coronal flux tubes of multiple temperatures. We see
+the creation of spatially expanded Kelvin-Helmholtz eddies along the loop,
+which deform the initial monolithic loop profile. For the case of driven
+oscillations, the Kelvin-Helmholtz instability develops despite physical
+dissipation, unless very high values of shear viscosity are used. Energy
+dissipation gets its highest values near the apex, but is present all along the
+loop. We observe an increased efficiency of wave heating once the kinetic
+energy saturates at the later stages of the simulation and a turbulent density
+profile has developed. The inclusion of gravity greatly alters the dynamic
+evolution of our systems and should not be ignored in future studies. Stronger
+physical dissipation leads to stronger wave heating in our set-ups. Finally,
+once the kinetic energy of the oscillating loop starts saturating, all the
+excess input energy turns into internal energy, resulting in more efficient
+wave heating.",1901.02676v2
+2019-01-31,Analysis and active control of geometrically nonlinear responses of smart FG porous plates with graphene nanoplatelets reinforcement based on Bézier extraction of NURBS,"In this paper, we propose an effective computational approach to analyze and
+active control of geometrically nonlinear responses of functionally graded (FG)
+porous plates with graphene nanoplatelets (GPLs) reinforcement integrated with
+piezoelectric layers. The key concept behind this work is to utilize
+isogeometric analysis (IGA) based on B\'ezier extraction technique and
+$C^0$-type higher-order shear deformation theory ($C^0$-HSDT). By applying
+B\'ezier extraction, the original Non-Uniform Rational B-Spline (NURBS) control
+meshes can be transformed into B\'ezier elements which allow us to inherit the
+standard numerical procedure like the standard finite element method (FEM). In
+this scenario, the approximation of mechanical displacement field is calculated
+via $C^0$-HSDT whilst the electric potential field is considered as a linear
+function across the thickness of each piezoelectric sublayer. The FG plate
+includes internal pores and GPLs dispersed into metal matrix either uniformly
+or non-uniformly along plate's thickness. To control responses of structures,
+the top and bottom surfaces of FG plate are firmly bonded with piezoelectric
+layers which are considered as sensor and actuator layers. The geometrically
+nonlinear equations are solved by Newton-Raphson iterative procedure and
+Newmark's integration. The influence of porosity coefficient, weight fraction
+of GPLs as well as external electrical voltage on geometrically nonlinear
+behaviors of plate structures with various distributions of porosity and GPLs
+are thoroughly investigated. A constant displacement and velocity feedback
+control approaches are then adopted to actively control geometrically nonlinear
+static and dynamic responses, where structural damping effect is taken into
+account, based on a closed-loop control with sensor and actuator layers.",1902.10806v2
+2019-04-18,Cosmic-ray transport from AMS-02 B/C data: benchmark models and interpretation,"This article aims at establishing new benchmark scenarios for Galactic
+cosmic-ray propagation in the GV-TV rigidity range, based on fits to the AMS-02
+B/C data with the USINE v3.5 propagation code. We employ a new fitting
+procedure, cautiously taking into account data systematic error correlations in
+different rigidity bins and considering Solar modulation potential and leading
+nuclear cross-section as nuisance parameters. We delineate specific low,
+intermediate, and high-rigidity ranges that can be related to both features in
+the data and peculiar microphysics mechanisms resulting in spectral breaks. We
+single out a scenario which yields excellent fits to the data and includes all
+the presumably relevant complexity, the BIG model. This model has two limiting
+regimes: (i) the SLIM model, a minimal diffusion-only setup, and (ii) the
+QUAINT model, a convection-reacceleration model where transport is tuned by
+non-relativistic effects. All models lead to robust predictions in the
+high-energy regime ($\gtrsim10$GV), i.e. independent of the propagation
+scenario: at $1\sigma$, the diffusion slope $\delta$ is $[0.43-0.53]$, whereas
+$K_{10}$, the diffusion coefficient at 10GV, is $[0.26-0.36]$kpc$^2$Myr$^{-1}$;
+we confirm the robustness of the high-energy break, with a typical value
+$\Delta_h\sim 0.2$. We also find a hint for a similar (reversed) feature at low
+rigidity around the B/C peak ($\sim 4$GV) which might be related to some
+effective damping scale in the magnetic turbulence.",1904.08917v2
+2019-05-06,Formation and decay of eddy currents generated by crossed surface waves,"The mass-transport induced by crossed surface waves consists of the Stokes
+and Euler contributions which are very different in nature. The first
+contribution is a generalization of Stokes drift for a plane wave in ideal
+fluid and the second contribution arises due to the fluid viscosity and it is
+excited by a force applied in the viscous sublayer near the fluid surface. We
+study the formation and decay of the induced mass-transport theoretically and
+experimentally and demonstrate that both contributions have different time
+scales for typical experimental conditions. The evolution of the Euler
+contribution is described by a diffusion equation, where the fluid kinematic
+viscosity plays the role of the diffusion coefficient, while the Stokes
+contribution evolves faster, feeling the additional damping near the system
+boundaries. The difference becomes more pronounced if the fluid surface is
+contaminated. We model the effect of contamination by a thin insoluble liquid
+film presented on the fluid surface with the compression modulus being the only
+non-zero rheological parameter of the film. Then the Euler contribution into
+the mass-transport becomes parametrically larger and the evolution of the
+Stokes contribution becomes parametrically faster. The parameter is the same in
+both cases and it is equal to the quality factor of surfaces waves, which is
+modified by the presence of a surface film. We infer the value of the
+compression modulus of the film by fitting the results of transient
+measurements of eddy currents and demonstrate that the obtained value leads to
+the correct ratio of amplitudes of horizontal and vertical velocities of the
+wave motion and is in reasonable agreement with the measured dissipation rate
+of surface waves.",1905.01875v2
+2019-10-30,A priori bounds for the $Φ^4$ equation in the full sub-critical regime,"We derive a priori bounds for the $\Phi^4$ equation in the full sub-critical
+regime using Hairer's theory of regularity structures. The equation is formally
+given by \begin{equation} \label{e}(\partial_t-\Delta)\phi = -\phi^3 + \infty
+\phi +\xi, \tag{$\star$} \end{equation} where the term $+\infty \phi$
+represents infinite terms that have to be removed in a renormalisation
+procedure. We emulate fractional dimensions $d<4$ by adjusting the regularity
+of the noise term $\xi$, choosing $\xi \in C^{-3+\delta}$. Our main result
+states that if $\phi$ satisfies this equation on a space-time cylinder $P=
+(0,1) \times \{ |x| \leq 1 \}$, then away from the boundary $\partial P$ the
+solution $\phi$ can be bounded in terms of a finite number of explicit
+polynomial expressions in $\xi$, and this bound holds uniformly over all
+possible choices of boundary data for $\phi$. The derivation of this bound
+makes full use of the super-linear damping effect of the non-linear term
+$-\phi^3$. A key part of our analysis consists of an appropriate re-formulation
+of the theory of regularity structures in the specific context of \eqref{e},
+which allows to couple the small scale control one obtains from this theory
+with a suitable large scale argument. Along the way we make several new
+observations and simplifications. Instead of a model $(\Pi_x)_x$ and the family
+of translation operators $(\Gamma_{x,y})_{x,y}$ we work with just a single
+object $(\mathbb{X}_{x, y})$ which acts on itself for translations, very much
+in the spirit of Gubinelli's theory of branched rough paths. Furthermore, we
+show that in the specific context of \eqref{e} the hierarchy of continuity
+conditions which constitute Hairer's definition of a \emph{modelled
+distribution} can be reduced to the single continuity condition on the
+""coefficient on the constant level"".",1910.13854v2
+2019-11-18,Wave measurements from ship mounted sensors in the Arctic marginal ice zone,"Increased research interest and economic activity in the Arctic raise the
+need for new observations of sea ice dynamics. Remote sensing as well as
+mathematical and numerical models of wave propagation in sea ice would benefit
+from more in situ data for validation. This study presents wave measurements in
+the marginal ice zone (MIZ) obtained from ship mounted sensors. The system
+combines altimeter readings from the ship bow with ship motion correction data
+to provide estimated single point ocean surface elevation. Significant wave
+height and mean wave period, as well as one-dimensional wave spectra are
+derived from the combined measurements. The results are compared with
+integrated parameters from a spectral wave model over a period of eight days in
+the open ocean, and with spectra and integrated parameters derived from motion
+detecting instruments placed on ice floes inside the MIZ. Mean absolute errors
+of the integrated parameters are in the range 15.0-18.9% when comparing with
+the spectral wave model and 1.0-9.6% when comparing with valid motion detecting
+instruments. The spatial wave damping coefficient is estimated by looking at
+the change in spectral wave amplitude found at discrete frequency values as the
+ship was moving along the longitudinal direction of the MIZ within time
+intervals where the wave field is found to be approximately constant in time.
+As expected from theory, high frequency waves are effectively dampened by the
+presence of sea ice. The observed wave attenuation rates compare favourably
+with a two-layer dissipation model. Our methodology can be regarded as a simple
+and reliable way to collect more waves-in-ice data as it can be easily added to
+any ship participating to ice expeditions, at little extra cost.",1911.07612v2
+2020-08-02,"Phase Diagram, Stability and Magnetic Properties of Nonlinear Excitations in Spinor Bose-Einstein Condensates","We present the phase diagram, the underlying stability and magnetic
+properties as well as the dynamics of nonlinear solitary wave excitations
+arising in the distinct phases of a harmonically confined spinor $F=1$
+Bose-Einstein condensate. Particularly, it is found that nonlinear excitations
+in the form of dark-dark-bright solitons exist in the antiferromagnetic and in
+the easy-axis phase of a spinor gas, being generally unstable in the former
+while possessing stability intervals in the latter phase. Dark-bright-bright
+solitons can be realized in the polar and the easy-plane phases as unstable and
+stable configurations respectively; the latter phase can also feature stable
+dark-dark-dark solitons. Importantly, the persistence of these types of states
+upon transitioning, by means of tuning the quadratic Zeeman coefficient from
+one phase to the other is unravelled. Additionally, the spin-mixing dynamics of
+stable and unstable matter waves is analyzed, revealing among others the
+coherent evolution of magnetic dark-bright, nematic dark-bright-bright and
+dark-dark-dark solitons. Moreover, for the unstable cases unmagnetized or
+magnetic droplet-like configurations and spin-waves consisting of regular and
+magnetic solitons are seen to dynamically emerge remaining thereafter robust
+while propagating for extremely large evolution times. Interestingly, exposing
+spinorial solitons to finite temperatures, their anti-damping in trap
+oscillation is showcased. It is found that the latter is suppressed for
+stronger bright soliton component ""fillings"". Our investigations pave the wave
+for a systematic production and analysis involving spin transfer processes of
+such waveforms which have been recently realized in ultracold experiments.",2008.00475v3
+2021-02-18,On stochastic heating and its phase-space signatures in low-$β$ kinetic turbulence,"We revisit the theory of stochastic heating of ions and investigate its
+phase-space signatures in kinetic turbulence of relevance to low-$\beta$
+portions of the solar wind. We retain a full scale-dependent approach in our
+treatment, and consider the case in which electric-field fluctuations can be
+described by a generalized Ohm's law that includes Hall and thermo-electric
+effects. These two electric-field terms provide the dominant contributions to
+stochastic ion heating when the ion-Larmor scale is much smaller than the ion
+skin depth, $\rho_{\mathrm{i}}\ll d_{\mathrm{i}}$, which is the case at
+$\beta{\ll}1$. Employing well-known spectral scaling laws for Alfv\'en-wave and
+kinetic-Alfv\'en-wave turbulent fluctuations, we obtain scaling relations
+characterizing the field-perpendicular particle-energization rate and energy
+diffusion coefficient associated with stochastic heating in these two regimes.
+Phase-space signatures of ion heating are then investigated using 3D
+hybrid-kinetic simulations of continuously driven Alfv\'enic turbulence at low
+$\beta$. In these simulations, energization of ions parallel to the magnetic
+field is sub-dominant compared to its perpendicular counterpart
+($Q_{\parallel,\mathrm{i}}\ll Q_{\perp,\mathrm{i}}$), and the fraction of
+turbulent energy that goes into ion heating is ${\approx}75$\% at
+$\beta_{\mathrm{i}}=0.3$ and ${\approx}40$\% at
+$\beta_{\mathrm{i}}{\simeq}0.1$. The phase-space signatures of ion energization
+are consistent with Landau-resonant collisionless damping and a
+($\beta$-dependent) combination of ion-cyclotron and stochastic heating. We
+demonstrate good agreement between our theory and various signatures associated
+with the stochastic portion of the heating. We discuss the effect of
+intermittency on stochastic heating and the implications of our work for the
+interpretation of stochastic heating in solar-wind spacecraft data.",2102.09654v2
+2021-06-16,Accurate and efficient hydrodynamic analysis of structures with sharp edges by the Extended Finite Element Method (XFEM): 2D studies,"Achieving accurate numerical results of hydrodynamic loads based on the
+potential-flow theory is very challenging for structures with sharp edges, due
+to the singular behavior of the local-flow velocities. In this paper, we
+introduce the Extended Finite Element Method (XFEM) to solve fluid-structure
+interaction problems involving sharp edges on structures. Four different FEM
+solvers, including conventional linear and quadratic FEMs as well as their
+corresponding XFEM versions with local enrichment by singular basis functions
+at sharp edges, are implemented and compared. To demonstrate the accuracy and
+efficiency of the XFEMs, a thin flat plate in an infinite fluid domain and a
+forced heaving rectangle at the free surface, both in two dimensions, will be
+studied. For the flat plate, the mesh convergence studies are carried out for
+both the velocity potential in the fluid domain and the added mass, and the
+XFEMs show apparent advantages thanks to their local enhancement at the sharp
+edges. Three different enrichment strategies are also compared, and suggestions
+will be made for the practical implementation of the XFEM. For the forced
+heaving rectangle, the linear and 2nd order mean wave loads are studied. Our
+results confirm the previous conclusion in the literature that it is not
+difficult for a conventional numerical model to obtain convergent results for
+added mass and damping coefficients. However, when the 2nd order mean wave
+loads requiring the computation of velocity components are calculated via
+direct pressure integration, it takes a tremendously large number of elements
+for the conventional FEMs to get convergent results. On the contrary, the
+numerical results of XFEMs converge rapidly even with very coarse meshes,
+especially for the quadratic XFEM.",2106.08620v2
+2021-06-25,Validity of point-mass model in off-resonance dynamic atomic force microscopy,"The quantitative measurement of viscoelasticity of nano-scaleentities is an
+important goal of nanotechnology research and there is considerable progress
+with advent of dynamic Atomic Force Microscopy. The hydrodynamics of
+cantilever, the force sensor in AFM measurements, plays a pivotal role in
+quantitative estimates of nano-scale viscoelasticity. The point-mass
+model,wherein the AFM cantilever is approximated as a point mass with mass-less
+spring is widely used in dynamic AFM analysis and its validity, particularly in
+liquid environments, is debated. It is suggested that the cantilever must be
+treated as a continuous rectangular beam to obtain accurate estimates of
+nano-scale viscoelasticity of materials it is probing. Here, we derived
+equations, which relate stiffness and damping coefficient of the material under
+investigation to measured parameters, by approximating cantilever as a point
+mass and also considering the full geometric details. These equations are
+derived for both tip-excited as well as base excited cantilevers. We have
+performed off-resonance dynamic atomic force spectroscopy on a single protein
+molecule to investigate the validity of widely used point-mass model. We
+performed measurements with AFMs equipped with different cantilever excitation
+methods as well as detection schemes to measure cantilever response. The data
+was analyzed using both, continuous-beam model and the point-mass model. We
+found that both models yield same results when the experiments are performed in
+truly off-resonance regime with small amplitudes and the cantilever stiffness
+is much higher than the interaction stiffness. Our findings suggest that a
+simple point-mass approximation based model is adequate to describe the
+dynamics, provided care is taken while performing experiments so that the
+approximations used in these models are valid.",2106.13631v1
+2021-11-20,Current noise and Keldysh vertex function of an Anderson impurity in the Fermi liquid regime,"We present a complete microscopic Fermi-liquid description for
+next-to-leading order transport through an Anderson impurity under a finite
+bias voltage $V$. It is applicable to multilevel quantum dots without
+particle-hole or time-reversal symmetry, and is constructed based on the
+nonequilibrium Keldysh formalism, taking into account the current conservation
+between electrons in the impurity levels and the conduction bands.
+Specifically, we derive the formula for the current noise generated in the
+steady flow up to terms of order $(eV)^3$ at zero temperature $T=0$. To this
+end, we calculate the Keldysh vertex functions
+$\Gamma_{\sigma\sigma';\sigma'\sigma}^{ \nu_1\nu_2;\nu_3\nu_4} (\omega,\omega';
+\omega',\omega)$, which depend on branches $\nu_1, \nu_2, \nu_3$ and $\nu_4$ of
+the time-loop contour and on spin degrees of freedom $\sigma$ and $\sigma'$, up
+to linear-order terms with respect to $eV$, $T$, and frequencies $\omega$ and
+$\omega'$. The coefficients of these linear-order terms are determined by a set
+of the parameters, defined with respect to the equilibrium ground state: the
+phase shift, static susceptibilities, and nonlinear three-body susceptibilities
+of the impurity electrons. The low-energy expressions of the vertex components
+are shown to satisfy the Ward identities with the Keldysh Green's functions
+expanded up to terms of order $\omega^2$, $(eV)^2$, and $T^2$. We also find
+that the imaginary part of the Ward identities can be described in terms of the
+$eV$-dependent collision integrals for a single-quasiparticle excitation and
+that for a single quasiparticle-quasihole pair excitation. These collision
+integrals ensure the current conservation of the next-to-leading order
+Fermi-liquid transport due to the quasiparticles with a finite damping rate.",2111.10483v2
+2021-12-01,Numerical Study of Cosmic Ray Confinement through Dust Resonant Drag Instabilities,"We investigate the possibility of cosmic ray (CR) confinement by charged dust
+grains through resonant drag instabilities (RDIs). We perform
+magnetohydrodynamic particle-in-cell simulations of magnetized gas mixed with
+charged dust and cosmic rays, with the gyro-radii of dust and GeV CRs on
+$\sim\mathrm{AU}$ scales fully resolved. As a first study, we focus on one type
+of RDI wherein charged grains drift super-Alfv{\'e}nically, with Lorentz forces
+strongly dominating over drag forces. Dust grains are unstable to the RDIs and
+form concentrated columns and sheets, whose scale grows until saturating at the
+simulation box size. Initially perfectly-streaming CRs are strongly scattered
+by RDI-excited Alfv{\'e}n waves, with the growth rate of the CR perpendicular
+velocity components equaling the growth rate of magnetic field perturbations.
+These rates are well-predicted by analytic linear theory. CRs finally become
+isotropized and drift at least at $\sim v_\mathrm{A}$ by unidirectional
+Alfv\'{e}n waves excited by the RDIs, with a uniform distribution of the pitch
+angle cosine $\mu$ and a flat profile of the CR pitch angle diffusion
+coefficient $D_{\mu\mu}$ around $\mu = 0$, without the ""$90$ degree pitch angle
+problem."" With CR feedback on the gas included, $D_{\mu\mu}$ decreases by a
+factor of a few, indicating a lower CR scattering rate, because the
+backreaction on the RDI from the CR pressure adds extra wave damping, leading
+to lower quasi-steady-state scattering rates. Our study demonstrates that the
+dust-induced CR confinement can be very important under certain conditions,
+e.g., the dusty circumgalactic medium around quasars or superluminous galaxies.",2112.00752v2
+2022-03-09,"A comparison of variational upwinding schemes for geophysical fluids, and their application to potential enstrophy conserving discretisations","Methods for upwinding the potential vorticity in a compatible finite element
+discretisation of the rotating shallow water equations are studied. These
+include the well-known anticipated potential vorticity method (APVM),
+streamwise upwind Petrov-Galerkin (SUPG) method, and a recent approach where
+the trial functions are evaluated downstream within the reference element. In
+all cases the upwinding scheme conserves both potential vorticity and energy,
+since the antisymmetric structure of the equations is preserved. The APVM leads
+to a symmetric definite correction to the potential enstrophy that is
+dissipative and inconsistent, resulting in a turbulent state where the
+potential enstrophy is more strongly damped than for the other schemes. While
+the SUPG scheme is widely known to be consistent, since it modifies the test
+functions only, the downwinded trial function formulation results in the
+advection of downwind corrections. Results of the SUPG and downwinded trial
+function schemes are very similar in terms of both potential enstrophy
+conservation and turbulent spectra. The main difference between these schemes
+is in the energy conservation and residual errors. If just two nonlinear
+iterations are applied then the energy conservation errors are improved for the
+downwinded trial function formulation, reflecting a smaller residual error than
+for the SUPG scheme.
+  We also present formulations by which potential enstrophy is exactly
+integrated at each time level. Results using these formulations are observed to
+be stable in the absence of dissipation, despite the uncontrolled aliasing of
+grid scale turbulence. Using such a formulation and the APVM with a coefficient
+$\mathcal{O}(100)$ times smaller that its regular value leads to turbulent
+spectra that are greatly improved at the grid scale over the SUPG and
+downwinded trial function formulations with unstable potential enstrophy
+errors.",2203.04629v3
+2022-03-26,Ion Alfvén velocity fluctuations and implications for the diffusion of streaming cosmic rays,"The interstellar medium (ISM) of star-forming galaxies is magnetized and
+turbulent. Cosmic rays (CRs) propagate through it, and those with energies from
+$\sim\,\rm{GeV} - \rm{TeV}$ are likely subject to the streaming instability,
+whereby the wave damping processes balances excitation of resonant ionic
+Alfv\'en waves by the CRs, reaching an equilibrium in which the propagation
+speed of the CRs is very close to the local ion Alfv\'en velocity. The
+transport of streaming CRs is therefore sensitive to ionic Alfv\'en velocity
+fluctuations. In this paper we systematically study these fluctuations using a
+large ensemble of compressible MHD turbulence simulations. We show that for
+sub-Alfv\'enic turbulence, as applies for a strongly magnetized ISM, the ionic
+Alfv\'en velocity probability density function (PDF) is determined solely by
+the density fluctuations from shocked gas forming parallel to the magnetic
+field, and we develop analytical models for the ionic Alfv\'en velocity PDF up
+to second moments. For super-Alfv\'enic turbulence, magnetic and density
+fluctuations are correlated in complex ways, and these correlations as well as
+contributions from the magnetic fluctuations sets the ionic Alfv\'en velocity
+PDF. We discuss the implications of these findings for underlying ""macroscopic""
+diffusion mechanisms in CRs undergoing the streaming instability, including
+modeling the macroscopic diffusion coefficient for the parallel transport in
+sub-Alfv\'enic plasmas. We also describe how, for highly-magnetized turbulent
+gas, the gas density PDF, and hence column density PDF, can be used to access
+information about ionic Alfv\'en velocity structure from observations of the
+magnetized ISM.",2203.13952v3
+2022-06-24,"Data-driven reduced order models using invariant foliations, manifolds and autoencoders","This paper explores how to identify a reduced order model (ROM) from a
+physical system. A ROM captures an invariant subset of the observed dynamics.
+We find that there are four ways a physical system can be related to a
+mathematical model: invariant foliations, invariant manifolds, autoencoders and
+equation-free models. Identification of invariant manifolds and equation-free
+models require closed-loop manipulation of the system. Invariant foliations and
+autoencoders can also use off-line data. Only invariant foliations and
+invariant manifolds can identify ROMs, the rest identify complete models.
+Therefore, the common case of identifying a ROM from existing data can only be
+achieved using invariant foliations.
+  Finding an invariant foliation requires approximating high-dimensional
+functions. For function approximation, we use polynomials with compressed
+tensor coefficients, whose complexity increases linearly with increasing
+dimensions. An invariant manifold can also be found as the fixed leaf of a
+foliation. This only requires us to resolve the foliation in a small
+neighbourhood of the invariant manifold, which greatly simplifies the process.
+Combining an invariant foliation with the corresponding invariant manifold
+provides an accurate ROM. We analyse the ROM in case of a focus type
+equilibrium, typical in mechanical systems. The nonlinear coordinate system
+defined by the invariant foliation or the invariant manifold distorts
+instantaneous frequencies and damping ratios, which we correct. Through
+examples we illustrate the calculation of invariant foliations and manifolds,
+and at the same time show that Koopman eigenfunctions and autoencoders fail to
+capture accurate ROMs under the same conditions.",2206.12269v3
+2022-10-23,Tidally excited gravity waves in the cores of solar-type stars: resonances and critical-layer formation,"We simulate the propagation and dissipation of tidally induced nonlinear
+gravity waves in the cores of solar-type stars. We perform hydrodynamical
+simulations of a previously developed Boussinesq model using a spectral-element
+code to study the stellar core as a wave cavity that is periodically forced at
+the outer boundary with a given azimuthal wavenumber and an adjustable
+frequency. For low-amplitude forcing, the system exhibits resonances with
+standing g-modes at particular frequencies, corresponding to a situation in
+which the tidal torque is highly frequency-dependent. For high-amplitude
+forcing, the excited waves break promptly near the centre and spin up the core
+so that subsequent waves are absorbed in an expanding critical layer, as found
+in previous work, leading to a tidal torque with a smooth frequency-dependence.
+For intermediate-amplitude forcing, we find that linear damping of the waves
+gradually spins up the core such that the resonance condition can be altered
+drastically. The system can evolve towards or away from g-mode resonances,
+depending on the difference between the forcing frequency and the closest
+eigenfrequency. Eventually, a critical layer forms and absorbs the incoming
+waves, leading to a situation similar to the high-amplitude case in which the
+waves break promptly. We study the dependence of this process on the forcing
+amplitude and frequency, as well as on the diffusion coefficients. We emphasize
+that the small Prandtl number in the centre of solar-like stars facilitates the
+development of a differentially rotating core owing to the nonlinear feedback
+of waves. Our simulations and analysis reveal that this important mechanism may
+drastically change the phase of gravity waves and thus the classical picture of
+resonance locking in solar-type stars needs to be revised.",2210.12880v2
+1993-06-22,Weakly Damped Modes in Star Clusters and Galaxies,"A perturber may excite a coherent mode in a star cluster or galaxy. If the
+stellar system is stable, it is commonly assumed that such a mode will be
+strongly damped and therefore of little practical consequence other than
+redistributing momentum and energy deposited by the perturber. This paper
+demonstrates that this assumption is false; weakly damped modes exist and may
+persist long enough to have observable consequences. To do this, a method for
+investigating the dispersion relation for spherical stellar systems and for
+locating weakly damped modes in particular is developed and applied to King
+models of varying concentration. This leads to the following remarkable result:
+King models exhibit {\it very} weakly damped $m=1$ modes over a wide range of
+concentration ($0.67\le c\le1.5$ have been examined). The predicted damping
+time is tens to hundreds of crossing times. This mode causes the peak density
+to shift from and slowly revolve about the initial center. The existence of the
+mode is supported by n-body simulation. Higher order modes and possible
+astronomical consequences are discussed. Weakly damped modes, for example, may
+provide a natural explanation for observed discrepancies between density and
+kinematic centers in galaxies, the location of velocity cusps due to massive
+black holes, and $m=1$ disturbances of disks embedded in massive halos.
+Gravitational shocking may excite the $m=1$ mode in globular clusters, which
+could modify their subsequent evolution and displace the positions of exotic
+remnants.",9306020v1
+1997-12-03,On the Evolution of Damped Lyman Alpha Systems to Galactic Disks,"The mean metallicity of the thick disk of the Galaxy is 0.5 dex higher than
+that of the damped Lyman alpha systems. This has been interpreted to argue that
+stars in the former do not arise out of gas in the latter. Using new
+metallicity and H I column-density data we show the metal-rich damped systems
+do contain sufficient baryons at the thick-disk metallicity to account for the
+stellar masses of thick disks. Comparing our kinematic data with the
+metallicities we show that damped Lyman alpha systems exhibiting the largest
+profile velocity widths span a narrow range of high metallicities, while
+systems with small velocity widths span a wider range of metallicities. This is
+naturally explained by passage of the damped Lyman alpha sightlines through
+rapidly rotating disks with negative radial gradients in metallicity. The
+systematically lower N(H I) of systems with high velocity widths indicates (a)
+the gaseous disks have centrally located holes, and (b) an apparent
+inconsistency with the protogalactic clump model for damped Lyman alpha
+systems. The higher metallicity of systems with low N(H I) further implies that
+stars rather than gas dominate the baryonic content of the most metal-rich
+damped systems.",9712050v1
+1998-10-23,Chemical Abundances of the Damped Lya Systems at z>1.5,"We present chemical abundance measurements for 19 damped lya systems observed
+with HIRES on the 10m W.M. Keck Telescope. Our principal goal is to investigate
+the abundance patterns of the damped systems and thereby determine the
+underlying physical processes which dominate their chemical evolution. We place
+particular emphasis on gauging the relative importance of two complementary
+effects often invoked to explain the damped lya abundances: (1) nucleosynthetic
+enrichment from Type II supernovae and (2) an ISM-like dust depletion pattern.
+  Similar to the principal results of Lu et al. (1996), our observations lend
+support both for dust depletion and Type II SN enrichment. Specifically, the
+observed overabundance of Zn/Fe and underabundance of Ni/Fe relative to solar
+abundances suggest significant dust depletion within the damped lya systems.
+Meanwhile, the relative abundances of Al, Si, and Cr vs. Fe are consistent with
+both dust depletion and Type II supernova enrichment. Our measurements of Ti/Fe
+and the Mn/Fe measurements from Lu et al. (1996), however, cannot be explained
+by dust depletion and indicate an underlying Type II SN pattern. Finally, the
+observed values of [S/Fe] are inconsistent with the combined effects of dust
+depletion and the nucleosynthetic yields expected for Type II supernovae. This
+last result emphasizes the need for another physical process to explain the
+damped lya abundance patterns.
+  We also examine the metallicity of the damped lya systems both with respect
+to Zn/H and Fe/H. Our results confirm previous surveys by Pettini and
+collaborators, i.e., [<Zn/H>] = -1.15 +/- 0.15 dex. [abridged]",9810381v1
+2002-04-03,The role of damped Alfven waves on magnetospheric accretion models of young stars,"We examine the role of Alfven wave damping in heating the plasma in the
+magnetic funnels of magnetospheric accretion models of young stars. We study
+four different damping mechanisms of the Alfven waves: nonlinear, turbulent,
+viscous-resistive and collisional. Two different possible origins for the
+Alfven waves are discussed: 1) Alfven waves generated at the surface of the
+star by the shock produced by the infalling matter; and 2) Alfven waves
+generated locally in the funnel by the Kelvin-Helmholtz instability. We find
+that, in general, the damping lengths are smaller than the tube length. Since
+thermal conduction in the tube is not efficient, Alfven waves generated only at
+the star's surface cannot heat the tube to the temperatures necessary to fit
+the observations. Only for very low frequency Alfven waves ~10^{-5} the ion
+cyclotron frequency, is the viscous-resistive damping length greater than the
+tube length. In this case, the Alfven waves produced at the surface of the star
+are able to heat the whole tube. Otherwise, local production of Alfven waves is
+required to explain the observations. The turbulence level is calculated for
+different frequencies for optically thin and thick media. We find that
+turbulent velocities varies greatly for different damping mechanisms, reaching
+\~100 km s^{-1} for the collisional damping of small frequency waves.",0204056v1
+2009-09-19,Resonantly Damped Kink Magnetohydrodynamic Waves in a Partially Ionized Filament Thread,"Transverse oscillations of solar filament and prominence threads have been
+frequently reported. These oscillations have the common features of being of
+short period (2-10 min) and being damped after a few periods. Kink
+magnetohydrodynamic (MHD) wave modes have been proposed as responsible for the
+observed oscillations, whereas resonant absorption in the Alfven continuum and
+ion-neutral collisions are the best candidates to be the damping mechanisms.
+Here, we study both analytically and numerically the time damping of kink MHD
+waves in a cylindrical, partially ionized filament thread embedded in a coronal
+environment. The thread model is composed of a straight and thin, homogeneous
+filament plasma, with a transverse inhomogeneous transitional layer where the
+plasma physical properties vary continuously from filament to coronal
+conditions. The magnetic field is homogeneous and parallel to the thread axis.
+We find that the kink mode is efficiently damped by resonant absorption for
+typical wavelengths of filament oscillations, the damping times being
+compatible with the observations. Partial ionization does not affect the
+process of resonant absorption, and the filament plasma ionization degree is
+only important for the damping for wavelengths much shorter than those
+observed. To our knowledge, this is the first time that the phenomenon of
+resonant absorption is studied in a partially ionized plasma.",0909.3599v1
+2009-10-15,Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionized prominence plasma: Effect of helium,"Prominences are partially ionized, magnetized plasmas embedded in the solar
+corona. Damped oscillations and propagating waves are commonly observed. These
+oscillations have been interpreted in terms of magnetohydrodynamic (MHD) waves.
+Ion-neutral collisions and non-adiabatic effects (radiation losses and thermal
+conduction) have been proposed as damping mechanisms. We study the effect of
+the presence of helium on the time damping of non-adiabatic MHD waves in a
+plasma composed by electrons, protons, neutral hydrogen, neutral helium (He I),
+and singly ionized helium (He II) in the single-fluid approximation. The
+dispersion relation of linear non-adiabatic MHD waves in a homogeneous,
+unbounded, and partially ionized prominence medium is derived. The period and
+the damping time of Alfven, slow, fast, and thermal waves are computed. A
+parametric study of the ratio of the damping time to the period with respect to
+the helium abundance is performed. The efficiency of ion-neutral collisions as
+well as thermal conduction is increased by the presence of helium. However, if
+realistic abundances of helium in prominences (~10%) are considered, this
+effect has a minor influence on the wave damping. The presence of helium can be
+safely neglected in studies of MHD waves in partially ionized prominence
+plasmas.",0910.2883v1
+2009-12-21,The effect of longitudinal flow on resonantly damped kink oscillations,"The most promising mechanism acting towards damping the kink oscillations of
+coronal loops is resonant absorption. In this context most of previous studies
+neglected the effect of the obvious equilibrium flow along magnetic field
+lines. The flows are in general sub-Alfv\'enic and hence comparatively slow.
+Here we investigate the effect of an equilibrium flow on the resonant
+absorption of linear kink MHD waves in a cylindrical magnetic flux tube with
+the aim of determining the changes in the frequency of the forward and backward
+propagating waves and in the modification of the damping times due to the flow.
+A loop model with both the density and the longitudinal flow changing in the
+radial direction is considered. We use the thin tube thin boundary (TTTB)
+approximation in order to calculate the damping rates. The full resistive
+eigenvalue problem is also solved without assuming the TTTB approximation.
+Using the small ratio of flow and Alfv\'en speeds we derive simple analytical
+expressions to the damping rate. The analytical expressions are in good
+agreement with the resistive eigenmode calculations. Under typical coronal
+conditions the effect of the flow on the damped kink oscillations is small when
+the characteristic scale of the density layer is similar or smaller than the
+characteristic width of the velocity layer. However, in the opposite situation
+the damping rates can be significantly altered, specially for the backward
+propagating wave which is undamped while the forward wave is overdamped.",0912.4136v1
+2010-07-12,Seismology of Standing Kink Oscillations of Solar Prominence Fine Structures,"We investigate standing kink magnetohydrodynamic (MHD) oscillations in a
+prominence fine structure modeled as a straight and cylindrical magnetic tube
+only partially filled with the prominence material, and with its ends fixed at
+two rigid walls representing the solar photosphere. The prominence plasma is
+partially ionized and a transverse inhomogeneous transitional layer is included
+between the prominence thread and the coronal medium. Thus, ion-neutral
+collisions and resonant absorption are the considered damping mechanisms.
+Approximate analytical expressions of the period, the damping time, and their
+ratio are derived for the fundamental mode in the thin tube and thin boundary
+approximations. We find that the dominant damping mechanism is resonant
+absorption, which provides damping ratios in agreement with the observations,
+whereas ion-neutral collisions are irrelevant for the damping. The values of
+the damping ratio are independent of both the prominence thread length and its
+position within the magnetic tube, and coincide with the values for a tube
+fully filled with the prominence plasma. The implications of our results in the
+context of the MHD seismology technique are discussed, pointing out that the
+reported short-period (2 - 10 min) and short-wavelength (700 - 8,000 km) thread
+oscillations may not be consistent with a standing mode interpretation and
+could be related to propagating waves. Finally, we show that the inversion of
+some prominence physical parameters, e.g., Alfv\'en speed, magnetic field
+strength, transverse inhomogeneity length-scale, etc., is possible using
+observationally determined values of the period and damping time of the
+oscillations along with the analytical approximations of these quantities.",1007.1959v2
+2012-10-30,Mode- and size-dependent Landau-Lifshitz damping in magnetic nanostructures: Evidence for non-local damping,"We demonstrate a strong dependence of the effective damping on the nanomagnet
+size and the particular spin-wave mode that can be explained by the theory of
+intralayer transverse-spin-pumping. The effective Landau-Lifshitz damping is
+measured optically in individual, isolated nanomagnets as small as 100 nm. The
+measurements are accomplished by use of a novel heterodyne magneto-optical
+microwave microscope with unprecedented sensitivity. Experimental data reveal
+multiple standing spin-wave modes that we identify by use of micromagnetic
+modeling as having either localized or delocalized character, described
+generically as end- and center-modes. The damping parameter of the two modes
+depends on both the size of the nanomagnet as well as the particular spin-wave
+mode that is excited, with values that are enhanced by as much as 40% relative
+to that measured for an extended film. Contrary to expectations based on the ad
+hoc consideration of lithography-induced edge damage, the damping for the
+end-mode decreases as the size of the nanomagnet decreases. The data agree with
+the theory for damping caused by the flow of intralayer transverse
+spin-currents driven by the magnetization curvature. These results have serious
+implications for the performance of nanoscale spintronic devices such as
+spin-torque-transfer magnetic random access memory.",1210.8118v3
+2012-11-21,Kinetic theory of surface plasmon polariton in semiconductor nanowires,"Based on the semiclassical model Hamiltonian of the surface plasmon polariton
+and the nonequilibrium Green-function approach, we present a microscopic
+kinetic theory to study the influence of the electron scattering on the
+dynamics of the surface plasmon polariton in semiconductor nanowires. The
+damping of the surface plasmon polariton originates from the resonant
+absorption by the electrons (Landau damping), and the corresponding damping
+exhibits size-dependent oscillations and distinct temperature dependence
+without any scattering. The scattering influences the damping by introducing a
+broadening and a shifting to the resonance. To demonstrate this, we investigate
+the damping of the surface plasmon polariton in InAs nanowires in the presence
+of the electron-impurity, electron-phonon and electron-electron Coulomb
+scatterings. The main effect of the electron-impurity and electron-phonon
+scatterings is to introduce a broadening, whereas the electron-electron Coulomb
+scattering can not only cause a broadening, but also introduce a shifting to
+the resonance. For InAs nanowires under investigation, the broadening due to
+the electron-phonon scattering dominates. As a result, the scattering has a
+pronounced influence on the damping of the surface plasmon polariton: The
+size-dependent oscillations are smeared out and the temperature dependence is
+also suppressed in the presence of the scattering. These results demonstrate
+the the important role of the scattering on the surface plasmon polariton
+damping in semiconductor nanowires.",1211.5055v2
+2013-11-12,Damping filter method for obtaining spatially localized solutions,"Spatially localized structures are key components of turbulence and other
+spatio-temporally chaotic systems. From a dynamical systems viewpoint, it is
+desirable to obtain corresponding exact solutions, though their existence is
+not guaranteed. A damping filter method is introduced to obtain variously
+localized solutions, and adopted into two typical cases. This method introduces
+a spatially selective damping effect to make a good guess at the exact
+solution, and we can obtain an exact solution through a continuation with the
+damping amplitude. First target is a steady solution to Swift-Hohenberg
+equation, which is a representative of bi-stable systems in which localized
+solutions coexist, and a model for span-wisely localized cases. Not only
+solutions belonging to the well-known snaking branches but also those belonging
+to an isolated branch known as ""isolas"" are found with a continuation paths
+between them in phase space extended with the damping amplitude. This indicates
+that this spatially selective excitation mechanism has an advantage in
+searching spatially localized solutions. Second target is a spatially localized
+traveling-wave solution to Kuramoto-Sivashinsky equation, which is a model for
+stream-wisely localized cases. Since the spatially selective damping effect
+breaks Galilean and translational invariances, the propagation velocity cannot
+be determined uniquely while the damping is active, and a singularity arises
+when these invariances are recovered. We demonstrate that this singularity can
+be avoided by imposing a simple condition, and a localized traveling-wave
+solution is obtained with a specific propagation speed.",1311.2792v2
+2014-09-19,Highly confined low-loss plasmons in graphene-boron nitride heterostructures,"Graphene plasmons were predicted to possess ultra-strong field confinement
+and very low damping at the same time, enabling new classes of devices for deep
+subwavelength metamaterials, single-photon nonlinearities, extraordinarily
+strong light-matter interactions and nano-optoelectronic switches. While all of
+these great prospects require low damping, thus far strong plasmon damping was
+observed, with both impurity scattering and many-body effects in graphene
+proposed as possible explanations. With the advent of van der Waals
+heterostructures, new methods have been developed to integrate graphene with
+other atomically flat materials. In this letter we exploit near-field
+microscopy to image propagating plasmons in high quality graphene encapsulated
+between two films of hexagonal boron nitride (h-BN). We determine dispersion
+and particularly plasmon damping in real space. We find unprecedented low
+plasmon damping combined with strong field confinement, and identify the main
+damping channels as intrinsic thermal phonons in the graphene and dielectric
+losses in the h-BN. The observation and in-depth understanding of low plasmon
+damping is the key for the development of graphene nano-photonic and
+nano-optoelectronic devices.",1409.5674v1
+2015-09-02,Energy Dependence of Synchrotron X-Ray Rims in Tycho's Supernova Remnant,"Several young supernova remnants exhibit thin X-ray bright rims of
+synchrotron radiation at their forward shocks. Thin rims require strong
+magnetic field amplification beyond simple shock compression if rim widths are
+only limited by electron energy losses. But, magnetic field damping behind the
+shock could produce similarly thin rims with less extreme field amplification.
+Variation of rim width with energy may thus discriminate between competing
+influences on rim widths. We measured rim widths around Tycho's supernova
+remnant in 5 energy bands using an archival 750 ks Chandra observation. Rims
+narrow with increasing energy and are well described by either loss-limited or
+damped scenarios, so X-ray rim width-energy dependence does not uniquely
+specify a model. But, radio counterparts to thin rims are not loss-limited and
+better reflect magnetic field structure. Joint radio and X-ray modeling favors
+magnetic damping in Tycho's SNR with damping lengths ~1--5% of remnant radius
+and magnetic field strengths ~50--400 $\mu$G assuming Bohm diffusion. X-ray rim
+widths are ~1% of remnant radius, somewhat smaller than inferred damping
+lengths. Electron energy losses are important in all models of X-ray rims,
+suggesting that the distinction between loss-limited and damped models is
+blurred in soft X-rays. All loss-limited and damping models require magnetic
+fields $\gtrsim$ 20 $\mu$G, affirming the necessity of magnetic field
+amplification beyond simple compression.",1509.00877v1
+2016-02-02,Forward Modelling of Propagating Slow Waves in Coronal Loops and Their Frequency-Dependent Damping,"Propagating slow waves in coronal loops exhibit a damping which depends upon
+the frequency of the waves. In this study we aim to investigate the
+relationship of the damping length (L$_d$) with the frequency of the
+propagating wave. We present a 3-D coronal loop model with uniform density and
+temperature and investigate the frequency dependent damping mechanism for the
+four chosen wave periods. We include the thermal conduction to damp the waves
+as they propagate through the loop. The numerical model output has been forward
+modelled to generate synthetic images of SDO/AIA 171 \r{A} and 193 \r{A}
+channels. The use of forward modelling, which incorporates the atomic emission
+properties into the intensity images, allows us to directly compare our results
+with the real observations. The results show that the damping lengths vary
+linearly with the periods. We also measure the contributions of the emission
+properties on the damping lengths by using density values from the simulation.
+In addition to that} we have also calculated the theoretical dependence of
+L$_d$ with wave periods and showed that it is consistent with the results we
+obtained from the numerical modelling and earlier observations.",1602.00787v1
+2016-05-11,Damping of prominence longitudinal oscillations due to mass accretion,"We study the damping of longitudinal oscillations of a prominence thread
+caused by the mass accretion. In this model we considered a thin curved
+magnetic tube filled with the plasma. The parts of the tube at the two sides of
+the thread are filled with hot rarefied plasma. We assume that there are flows
+of rarefied plasma toward the thread caused by the plasma evaporation at the
+magnetic tube footpoints. Our main assumption is that the hot plasma is
+instantaneously accommodated by the thread when it arrives at the thread, and
+its temperature and density become equal to those of the thread. Then we derive
+the system of ordinary differential equations describing the thread dynamics.
+We consider linear and nonlinear oscillation. The nonlinearity reduces the
+damping time, however this reduction is small. The damping time is inversely
+proportional to the accretion rate. We also obtain that the oscillation periods
+decrease with time. However even for the largest initial oscillation amplitude
+considered in our article the period reduction does not exceed 20%. We conclude
+that the mass accretion can damp the motion of the threads rapidly. Thus, this
+mechanism can explain the observed strong damping of large-amplitude
+longitudinal oscillations. In addition, the damping time can be used to
+determine the mass accretion rate and indirectly the coronal heating.",1605.03376v1
+2016-11-17,Inductive detection of field-like and damping-like AC inverse spin-orbit torques in ferromagnet/normal metal bilayers,"Functional spintronic devices rely on spin-charge interconversion effects,
+such as the reciprocal processes of electric field-driven spin torque and
+magnetization dynamics-driven spin and charge flow. Both damping-like and
+field-like spin-orbit torques have been observed in the forward process of
+current-driven spin torque and damping-like inverse spin-orbit torque has been
+well-studied via spin pumping into heavy metal layers. Here we demonstrate that
+established microwave transmission spectroscopy of ferromagnet/normal metal
+bilayers under ferromagnetic resonance can be used to inductively detect the AC
+charge currents driven by the inverse spin-charge conversion processes. This
+technique relies on vector network analyzer ferromagnetic resonance (VNA-FMR)
+measurements. We show that in addition to the commonly-extracted spectroscopic
+information, VNA-FMR measurements can be used to quantify the magnitude and
+phase of all AC charge currents in the sample, including those due to spin
+pumping and spin-charge conversion. Our findings reveal that
+Ni$_{80}$Fe$_{20}$/Pt bilayers exhibit both damping-like and field-like inverse
+spin-orbit torques. While the magnitudes of both the damping-like and
+field-like inverse spin-orbit torque are of comparable scale to prior reported
+values for similar material systems, we observed a significant dependence of
+the damping-like magnitude on the order of deposition. This suggests interface
+quality plays an important role in the overall strength of the damping-like
+spin-to-charge conversion.",1611.05798v2
+2016-12-30,Spectroscopic evidence of Alfvén wave damping in the off-limb solar corona,"We investigate off-limb active region and quiet Sun corona using
+spectroscopic data. Active region is clearly visible in several spectral lines
+formed in the temperature range of 1.1--2.8 MK. We derive electron number
+density using line ratio method, and non-thermal velocity in the off-limb
+region up to the distance of 140 Mm. We compare density scale heights derived
+from several spectral line pairs with expected scale heights as per hydrostatic
+equilibrium model. Using several isolated and unblended spectral line profiles,
+we estimate non-thermal velocities in active region and quiet Sun. Non-thermal
+velocities obtained from warm lines in active region first show increase and
+later show either decrease or almost constant value with height in the far
+off-limb region, whereas hot lines show consistent decrease. However, in the
+quiet Sun region, non-thermal velocities obtained from various spectral lines
+show either gradual decrease or remain almost constant with height. Using these
+obtained parameters, we further calculate Alfv\'en wave energy flux in the both
+active and quiet Sun regions. We find significant decrease in wave energy
+fluxes with height, and hence provide evidence of Alfv\'en wave damping.
+Furthermore, we derive damping lengths of Alfv\'en waves in the both regions
+and find them to be in the range of 25-170 Mm. Different damping lengths
+obtained at different temperatures may be explained as either possible
+temperature dependent damping or measurements obtained in different coronal
+structures formed at different temperatures along the line-of-sight.
+Temperature dependent damping may suggest some role of thermal conduction in
+the damping of Alfv\'en waves in the lower corona.",1612.09551v2
+2017-01-04,Controlling plasmon modes and damping in buckled two-dimensional material open systems,"Full ranges of both hybrid plasmon-mode dispersions and their damping are
+studied systematically by our recently developed mean-field theory in open
+systems involving a conducting substrate and a two-dimensional (2D) material
+with a buckled honeycomb lattice, such as silicene, germanene, and a group
+\rom{4} dichalcogenide as well. In this hybrid system, the single plasmon mode
+for a free-standing 2D layer is split into one acoustic-like and one
+optical-like mode, leading to a dramatic change in the damping of plasmon
+modes. In comparison with gapped graphene, critical features associated with
+plasmon modes and damping in silicene and molybdenum disulfide are found with
+various spin-orbit and lattice asymmetry energy bandgaps, doping types and
+levels, and coupling strengths between 2D materials and the conducting
+substrate. The obtained damping dependence on both spin and valley degrees of
+freedom is expected to facilitate measuring the open-system dielectric property
+and the spin-orbit coupling strength of individual 2D materials. The unique
+linear dispersion of the acoustic-like plasmon mode introduces additional
+damping from the intraband particle-hole modes which is absent for a
+free-standing 2D material layer, and the use of molybdenum disulfide with a
+large bandgap simultaneously suppresses the strong damping from the interband
+particle-hole modes.",1701.01084v1
+2017-04-05,Stimulated Brillouin scattering behaviors in different species ignition hohlraum plasmas in high-temperature and high-density region,"The presence of multiple ion species can add additional branches to the IAW
+dispersion relation and change the Landau damping significantly. Different IAW
+modes excited by stimulated Brillouin scattering (SBS) and different SBS
+behaviors in several typical ignition hohlraum plasmas in the high-temperature
+and high-density region have been researched by Vlasov-Maxwell simulation. The
+slow mode in HeH or CH plasmas is the least damped mode and will be excited in
+SBS, while the fast mode in AuB plasmas is the least damped mode and will be
+excited in SBS. Due to strong Landau damping, the SBS in H or HeH plasmas is
+strong convective instability, while the SBS in AuB plasmas is absolute
+instability due to the weak Landau damping. However, although the SBS in CH
+plasmas is weak convective instability in the linear theory, the SBS will
+transform into absolute instability due to decreasing linear Landau damping by
+particles trapping. These results give a detail research of the IAW modes
+excitation and the properties of SBS in different species plasmas, thus
+providing the possibility of controlling SBS by increasing the linear Landau
+damping of the IAW by changing ion species.",1704.02317v1
+2017-06-29,Resonant Absorption of Axisymmetric Modes in Twisted Magnetic Flux Tubes,"It has been shown recently that magnetic twist and axisymmetric MHD modes are
+ubiquitous in the solar atmosphere and therefore, the study of resonant
+absorption for these modes have become a pressing issue as it can have
+important consequences for heating magnetic flux tubes in the solar atmosphere
+and the observed damping. In this investigation, for the first time, we
+calculate the damping rate for axisymmetric MHD waves in weakly twisted
+magnetic flux tubes. Our aim is to investigate the impact of resonant damping
+of these modes for solar atmospheric conditions. This analytical study is based
+on an idealized configuration of a straight magnetic flux tube with a weak
+magnetic twist inside as well as outside the tube. By implementing the
+conservation laws derived by \cite{Sakurai:1991aa} and the analytic solutions
+for weakly twisted flux tubes obtained recently by \cite{Giagkiozis:2015apj},
+we derive a dispersion relation for resonantly damped axisymmetric modes in the
+spectrum of the Alfv\'{e}n continuum. We also obtain an insightful analytical
+expression for the damping rate in the long wavelength limit. Furthermore, it
+shown that both the longitudinal magnetic field and the density, which are
+allowed to vary continuously in the inhomogeneous layer, have a significant
+impact on the damping time. Given the conditions in the solar atmosphere,
+resonantly damped axisymmetric modes are highly likely to be ubiquitous and
+play an important role in energy dissipation.
+  We also suggest that given the character of these waves, it is likely that
+they have already been observed in the guise of Alfv\'{e}n waves.",1706.09665v1
+2017-08-16,Damping of an oscillating scalar field indirectly coupled to a thermal bath,"The damping process of a homogeneous oscillating scalar field that indirectly
+interacts with a thermal bath through a mediator field is investigated over a
+wide range of model parameters. We consider two types of mediator fields, those
+that can decay to the thermal bath and those that are individually stable but
+pair annihilate. The former case has been extensively studied in the literature
+by treating the damping as a local effect after integrating out the assumed
+close-to-equilibrium mediator field. The same approach does not apply if the
+mediator field is stable and freezes out of equilibrium. To account for the
+latter case, we adopt a non-local description of damping that is only
+meaningful when we consider full half-oscillations of the field being damped.
+The damping rates of the oscillating scalar field and the corresponding heating
+rate of the thermal bath in all bulk parameter regions are calculated in both
+cases, corroborating previous results in the direct decay case. Using the
+obtained results, the time it takes for the amplitude of the scalar field to be
+substantially damped is estimated.",1708.04865v2
+2018-09-14,Continuous and discrete damping reduction for systems with quadratic interaction,"We study the connection between Lagrangian and Hamiltonian descriptions of
+closed/open dynamics, for a collection of particles with quadratic interaction
+(closed system) and a sub-collection of particles with linear damping (open
+system). We consider both continuous and discrete versions of mechanics. We
+define the Damping Reduction as the mapping from the equations of motion of the
+closed system to those of the open one. As variational instruments for the
+obtention of these equations we use the Hamilton's principle (closed dynamics)
+and Lagrange-d'Alembert principle (open dynamics). We establish the
+commutativity of the branches Legendre transform + Damping Reduction and
+Damping Reduction+Legendre transform, where the Legendre transform is the usual
+mapping between Lagrangian and Hamiltonian mechanics. At a discrete level, this
+commutativity provides interesting insight about the resulting integrators.
+More concretely, Discrete Damping Reduction yields particular numerical schemes
+for linearly damped systems which are not symplectic anymore, but preserve some
+of the features of their symplectic counterparts from which they proceed (for
+instance the semi-implicitness in some cases). The theoretical results are
+illustrated with the examples of the heat bath and transmission lines. In the
+latter case some simulations are displayed, showing a better performance of the
+integrators with variational origin.",1809.05532v1
+2019-03-02,Complex Stiffness Model of Physical Human-Robot Interaction: Implications for Control of Performance Augmentation Exoskeletons,"Human joint dynamic stiffness plays an important role in the stability of
+performance augmentation exoskeletons. In this paper, we consider a new
+frequency domain model of the human joint dynamics which features a complex
+value stiffness. This complex stiffness consists of a real stiffness and a
+hysteretic damping. We use it to explain the dynamic behaviors of the human
+connected to the exoskeleton, in particular the observed non-zero low frequency
+phase shift and the near constant damping ratio of the resonant as stiffness
+and inertia vary. We validate this concept by experimenting with an elbow-joint
+exoskeleton testbed on a subject while modifying joint stiffness behavior,
+exoskeleton inertia, and strength augmentation gains. We compare three
+different models of elbow-joint dynamic stiffness: a model with real stiffness,
+viscous damping and inertia, a model with complex stiffness and inertia, and a
+model combining the previous two models. Our results show that the hysteretic
+damping term improves modeling accuracy, using a statistical F-test. Moreover
+this improvement is statistically more significant than using classical viscous
+damping term. In addition, we experimentally observe a linear relationship
+between the hysteretic damping and the real part of the stiffness which allows
+us to simplify the complex stiffness model as a 1-parameter system. Ultimately,
+we design a fractional order controller to demonstrate how human hysteretic
+damping behavior can be exploited to improve strength amplification performance
+while maintaining stability.",1903.00704v4
+2020-05-31,Optimal decay rates of the compressible Euler equations with time-dependent damping in $\mathbb R^n$: (II) over-damping case,"This paper is concerned with the multi-dimensional compressible Euler
+equations with time-dependent over-damping of the form
+$-\frac{\mu}{(1+t)^\lambda}\rho\boldsymbol u$ in $\mathbb R^n$, where $n\ge2$,
+$\mu>0$, and $\lambda\in[-1,0)$. This continues our previous work dealing with
+the under-damping case for $\lambda\in[0,1)$. We show the optimal decay
+estimates of the solutions such that for $\lambda\in(-1,0)$ and $n\ge2$,
+$\|\rho-1\|_{L^2(\mathbb R^n)}\approx(1+t)^{-\frac{1+\lambda}{4}n}$ and
+$\|\boldsymbol u\|_{L^2(\mathbb R^n)}\approx
+(1+t)^{-\frac{1+\lambda}{4}n-\frac{1-\lambda}{2}}$, which indicates that a
+stronger damping gives rise to solutions decaying optimally slower. For the
+critical case of $\lambda=-1$, we prove the optimal logarithmical decay of the
+perturbation of density for the damped Euler equations such that
+$\|\rho-1\|_{L^2(\mathbb R^n)}\approx |\ln(e+t)|^{-\frac{n}{4}}$ and
+$\|\boldsymbol u\|_{L^2(\mathbb R^n)}\approx
+(1+t)^{-1}\cdot|\ln(e+t)|^{-\frac{n}{4}-\frac{1}{2}}$ for $n\ge7$. The
+over-damping effect reduces the decay rates of the solutions to be slow, which
+causes us some technical difficulty in obtaining the optimal decay rates by the
+Fourier analysis method and the Green function method. Here, we propose a new
+idea to overcome such a difficulty by artfully combining the Green function
+method and the time-weighted energy method.",2006.00403v1
+2020-07-07,Nonlinear viscoelastic isolation for seismic vibration mitigation,"The aim of this paper is to assess the effectiveness of nonlinear
+viscoelastic damping in controlling base-excited vibrations. Specifically, the
+focus is on investigating the robustness of the nonlinear base isolation
+performance in controlling the system response due to a wide set of possible
+excitation spectra. The dynamic model is derived to study a simple structure
+whose base isolation is provided via a Rubber-Layer Roller Bearing (RLRB)
+(rigid cylinders rolling on rigid plates with highly damping rubber coatings)
+equipped with a nonlinear cubic spring, thus presenting both nonlinear damping
+and stiffness. We found that, under periodic loading, due to the non-monotonic
+bell-shaped viscoelastic damping arising from the viscoelastic rolling
+contacts, different dynamic regimes occur mostly depending on whether the
+damping peak is overcome or not. Interestingly, in the former case, poorly
+damped self-excited vibrations may be triggered by the steep damping decrease.
+Moreover, in order to investigate the robustness of the isolation performance,
+we consider a set of real seismic excitations, showing that tuned nonlinear
+RLRB provide loads isolation in a wider range of excitation spectra, compared
+to generic linear isolators. This is peculiarly suited for applications (such
+as seismic and failure engineering) in which the specific excitation spectrum
+is unknown a priori, and blind design on statistical data has to be employed.",2007.04378v1
+2021-01-20,Damped perturbations in stellar systems: Genuine modes and Landau-damped waves,"This research was stimulated by the recent studies of damping solutions in
+dynamically stable spherical stellar systems. Using the simplest model of the
+homogeneous stellar medium, we discuss nontrivial features of stellar systems.
+Taking them into account will make it possible to correctly interpret the
+results obtained earlier and will help to set up decisive numerical experiments
+in the future. In particular, we compare the initial value problem versus the
+eigenvalue problem. It turns out that in the unstable regime, the Landau-damped
+waves can be represented as a superposition of van Kampen modes {\it plus} a
+discrete damped mode, usually ignored in the stability study. This mode is a
+solution complex conjugate to the unstable Jeans mode. In contrast, the
+Landau-damped waves are not genuine modes: in modes, eigenfunctions depend on
+time as $\exp (-{\rm i} \omega t)$, while the waves do not have eigenfunctions
+on the real $v$-axis at all. However, `eigenfunctions' on the complex
+$v$-contours do exist. Deviations from the Landau damping are common and can be
+due to singularities or cut-off of the initial perturbation above some fixed
+value in the velocity space.",2101.08287v2
+2021-03-10,Dynamical Pose Estimation,"We study the problem of aligning two sets of 3D geometric primitives given
+known correspondences. Our first contribution is to show that this primitive
+alignment framework unifies five perception problems including point cloud
+registration, primitive (mesh) registration, category-level 3D registration,
+absolution pose estimation (APE), and category-level APE. Our second
+contribution is to propose DynAMical Pose estimation (DAMP), the first general
+and practical algorithm to solve primitive alignment problem by simulating
+rigid body dynamics arising from virtual springs and damping, where the springs
+span the shortest distances between corresponding primitives. We evaluate DAMP
+in simulated and real datasets across all five problems, and demonstrate (i)
+DAMP always converges to the globally optimal solution in the first three
+problems with 3D-3D correspondences; (ii) although DAMP sometimes converges to
+suboptimal solutions in the last two problems with 2D-3D correspondences, using
+a scheme for escaping local minima, DAMP always succeeds. Our third
+contribution is to demystify the surprising empirical performance of DAMP and
+formally prove a global convergence result in the case of point cloud
+registration by charactering local stability of the equilibrium points of the
+underlying dynamical system.",2103.06182v3
+2021-04-13,Apparent nonlinear damping triggered by quantum fluctuations,"Nonlinear damping, the change in damping rate with the amplitude of
+oscillations plays an important role in many electrical, mechanical and even
+biological oscillators. In novel technologies such as carbon nanotubes,
+graphene membranes or superconducting resonators, the origin of nonlinear
+damping is sometimes unclear. This presents a problem, as the damping rate is a
+key figure of merit in the application of these systems to extremely precise
+sensors or quantum computers. Through measurements of a superconducting
+resonator, we show that from the interplay of quantum fluctuations and the
+nonlinearity of a Josephson junction emerges a power-dependence in the
+resonator response which closely resembles nonlinear damping. The phenomenon
+can be understood and visualized through the flow of quasi-probability in phase
+space where it reveals itself as dephasing. Crucially, the effect is not
+restricted to superconducting circuits: we expect that quantum fluctuations or
+other sources of noise give rise to apparent nonlinear damping in systems with
+a similar conservative nonlinearity, such as nano-mechanical oscillators or
+even macroscopic systems.",2104.06464v2
+2023-07-26,Improving frequency response with synthetic damping available from fleets of distributed energy resources,"With the increasing use of renewable generation in power systems, responsive
+resources will be necessary to support primary frequency control in future
+low-inertia/under-damped power systems. Flexible loads can provide
+fast-frequency response services if coordinated effectively. However, practical
+implementations of such synthetic damping services require both effective local
+sensing and control at the device level and an ability to accurately estimate
+online and predict the available synthetic damping from a fleet. In addition,
+the inherent trade-off between a fleet being available for fast frequency
+response while providing other ancillary services needs to be characterized. In
+this context, the manuscript presents a novel, fully decentralized,
+packet-based controller for diverse flexible loads that dynamically prioritizes
+and interrupts loads to engender synthetic damping suitable for primary
+frequency control. Moreover, the packet-based control methodology is shown to
+accurately characterize the available synthetic damping in real-time, which is
+useful to aggregators and system operators. Furthermore, spectral analysis of
+historical frequency regulation data is used to produce a probabilistic bound
+on the expected available synthetic damping for primary frequency control from
+a fleet and the trade-off from concurrently providing secondary frequency
+control services. Finally, numerical simulation on IEEE test networks
+demonstrates the effectiveness of the proposed methodology.",2307.14498v1
+2023-12-11,Possible Contamination of the Intergalactic Medium Damping Wing in ULAS J1342+0928 by Proximate Damped Ly$α$ Absorption,"The red damping wing from neutral hydrogen in the intergalactic medium is a
+smoking-gun signal of ongoing reionization. One potential contaminant of the
+intergalactic damping wing signal is dense gas associated with foreground
+galaxies, which can give rise to proximate damped Ly$\alpha$ absorbers. The
+Ly$\alpha$ imprint of such absorbers on background quasars is indistinguishable
+from the intergalactic medium within the uncertainty of the intrinsic quasar
+continuum, and their abundance at $z\gtrsim7$ is unknown. Here we show that the
+complex of low-ionization metal absorption systems recently discovered by deep
+JWST/NIRSpec observations in the foreground of the $z=7.54$ quasar
+ULAS~J1342$+$0928 can potentially reproduce the quasar's spectral profile close
+to rest-frame Ly$\alpha$ without invoking a substantial contribution from the
+intergalactic medium, but only if the absorbing gas is extremely metal-poor
+($[{\rm O}/{\rm H}]\sim-3.5$). Such a low oxygen abundance has never been
+observed in a damped Ly$\alpha$ absorber at any redshift, but this possibility
+still complicates the interpretation of the spectrum. Our analysis highlights
+the need for deep spectroscopy of high-redshift quasars with JWST or ELT to
+""purify"" damping wing quasar samples, an exercise which is impossible for much
+fainter objects like galaxies.",2312.06747v1
+2024-02-13,Forecasts for Constraining Lorentz-violating Damping of Gravitational Waves from Compact Binary Inspirals,"Violation of Lorentz symmetry can result in two distinct effects in the
+propagation of the gravitational waves (GWs). One is a modified dispersion
+relation and another is a frequency-dependent damping of GWs. While the former
+has been extensively studied in the literature, in this paper we concentrate on
+the frequency-dependent damping effect that arises from several specific
+Lorentz-violating theories, such as spatial covariant gravities,
+Ho\v{r}ava-Lifshitz gravities, etc. This Lorentz-violating damping effect
+changes the damping rate of GWs at different frequencies and leads to an
+amplitude correction to the GW waveform of compact binary inspiral systems.
+With this modified waveform, we then use the Fisher information matrix to
+investigate the prospects of constraining the Lorentz-violating damping effect
+with GW observations. We consider both ground-based and space-based GW
+detectors, including the advanced LIGO, Einstein Telescope, Cosmic Explorer
+(CE), Taiji, TianQin, and LISA. Our results indicate that the ground-based
+detectors in general give tighter constraints than those from the space-based
+detectors. Among the considered three ground-based detectors, CE can give the
+tightest constraints on the Lorentz-violating damping effect, which improves
+the current constraint from LIGO-Virgo-KAGRA events by about 8 times.",2402.08240v1
+2024-03-13,Thermal Hall effect incorporating magnon damping in localized spin systems,"We propose a theory for thermal Hall transport mediated by magnons to address
+the impact of their damping resulting from magnon-magnon interactions in
+insulating magnets. This phenomenon is anticipated to be particularly
+significant in systems characterized by strong quantum fluctuations,
+exemplified by spin-1/2 systems. Employing a nonlinear flavor-wave theory, we
+analyze a general model for localized electron systems and develop a
+formulation for thermal conductivity based on a perturbation theory, utilizing
+bosonic Green's functions with a nonzero self-energy. We derive the expression
+of the thermal Hall conductivity incorporating magnon damping. To demonstrate
+the applicability of the obtained representation, we adopt it to two $S=1/2$
+quantum spin models on a honeycomb lattice. In calculations for these systems,
+we make use of the self-consistent imaginary Dyson equation approach at finite
+temperatures for evaluating the magnon damping rate. In both systems, the
+thermal Hall conductivity is diminished due to the introduction of magnon
+damping over a wide temperature range. This effect arises due to the smearing
+of magnon spectra with nonzero Berry curvatures. We also discuss the relation
+to the damping of chiral edge modes of magnons. Our formulation can be applied
+to various localized electron systems as we begin with a general Hamiltonian
+for these systems. Our findings shed light on a new aspect of topological
+magnonics emergent from many-body effects and will stimulate further
+investigations on the impact of magnon damping on topological phenomena.",2403.08478v1
+2024-04-02,A recipe for eccentricity and inclination damping for partial gap opening planets in 3D disks,"In a previous paper we showed that, like the migration speed, the
+eccentricity damping efficiency is modulated linearly by the depth of the
+partial gap a planet carves in the disk surface density profile, resulting in
+less efficient $e$-damping compared to the prescription commonly used in
+population synthesis works. Here, we extend our analysis to 3D, refining our
+$e$-damping formula and studying how the inclination damping efficiency is also
+affected. We perform high resolution 3D locally isothermal hydrodynamical
+simulations of planets with varying masses embedded in disks with varying
+aspect ratios and viscosities. We extract the gap profile and orbital damping
+timescales for fixed eccentricities and inclinations up to the disk scale
+height. The limit in gap depths below which vortices appear, in the
+low-viscosity case, happens roughly at the transition between classical type-I
+and type-II migration regimes. The orbital damping timescales can be described
+by two linear trends with a break around gap depths $\sim80\%$ and with slopes
+and intercepts depending on the eccentricity and inclination. These trends are
+understood on physical grounds and are reproduced by simple fitting formulas
+whose error is within the typically uncertainty of type-I torque formulas.
+Thus, our recipes for the gap depth and orbital damping efficiencies yield a
+simple description for planet-disk interactions to use in N-body codes in the
+case of partial gap opening planets that is consistent with high-resolution 3D
+hydro-simulations. Finally, we show examples of how our novel orbital damping
+prescription can affect the outcome of population synthesis experiments.",2404.02247v1
+2009-08-21,Surface Alfven Wave Damping in a 3D Simulation of the Solar Wind,"Here we investigate the contribution of surface Alfven wave damping to the
+heating of the solar wind in minima conditions. These waves are present in
+regions of strong inhomogeneities in density or magnetic field (e. g., the
+border between open and closed magnetic field lines). Using a 3-dimensional
+Magnetohydrodynamics (MHD) model, we calculate the surface Alfven wave damping
+contribution between 1-4 solar radii, the region of interest for both
+acceleration and coronal heating. We consider waves with frequencies lower than
+those that are damped in the chromosphere and on the order of those dominating
+the heliosphere. In the region between open and closed field lines, within a
+few solar radii of the surface, no other major source of damping has been
+suggested for the low frequency waves we consider here. This work is the first
+to study surface Alfven waves in a 3D environment without assuming a priori a
+geometry of field lines or magnetic and density profiles. We determine that
+waves with frequencies >2.8x10^-4 Hz are damped between 1-4 solar radii. In
+quiet sun regions, surface Alfven waves are damped at further distances
+compared to active regions, thus carrying additional wave energy into the
+corona. We compare the surface Alfven wave contribution to the heating by a
+variable polytropic index and find that it an order of magnitude larger than
+needed for quiet sun regions. For active regions the contribution to the
+heating is twenty percent. As it has been argued that a variable gamma acts as
+turbulence, our results indicate that surface Alfven wave damping is comparable
+to turbulence in the lower corona. This damping mechanism should be included
+self consistently as an energy driver for the wind in global MHD models.",0908.3146v1
+2017-11-21,Determination of spin Hall effect and spin diffusion length of Pt from self-consistent fitting of damping enhancement and inverse spin-orbit torque measurements,"Understanding the evolution of spin-orbit torque (SOT) with increasing
+heavy-metal thickness in ferromagnet/normal metal (FM/NM) bilayers is critical
+for the development of magnetic memory based on SOT. However, several
+experiments have revealed an apparent discrepancy between damping enhancement
+and damping-like SOT regarding their dependence on NM thickness. Here, using
+linewidth and phase-resolved amplitude analysis of vector network analyzer
+ferromagnetic resonance (VNA-FMR) measurements, we simultaneously extract
+damping enhancement and both field-like and damping-like inverse SOT in
+Ni$_{80}$Fe$_{20}$/Pt bilayers as a function of Pt thickness. By enforcing an
+interpretation of the data which satisfies Onsager reciprocity, we find that
+both the damping enhancement and damping-like inverse SOT can be described by a
+single spin diffusion length ($\approx$ 4 nm), and that we can separate the
+spin pumping and spin memory loss (SML) contributions to the total damping.
+This analysis indicates that less than 40% of the angular momentum pumped by
+FMR through the Ni$_{80}$Fe$_{20}$/Pt interface is transported as spin current
+into the Pt. On account of the SML and corresponding reduction in total spin
+current available for spin-charge transduction in the Pt, we determine the Pt
+spin Hall conductivity ($\sigma_\mathrm{SH} = (2.36 \pm 0.04)\times10^6
+\Omega^{-1} \mathrm{m}^{-1}$) and bulk spin Hall angle
+($\theta_\mathrm{SH}=0.387 \pm0.008$) to be larger than commonly-cited values.
+These results suggest that Pt can be an extremely useful source of SOT if the
+FM/NM interface can be engineered to minimize SML. Lastly, we find that
+self-consistent fitting of the damping and SOT data is best achieved by a model
+with Elliott-Yafet spin relaxation and extrinsic inverse spin Hall effect, such
+that both the spin diffusion length and spin Hall conductivity are proportional
+to the Pt charge conductivity.",1711.07654v2
+2019-09-19,"Nonlinear energy loss in the oscillations of coated and uncoated bubbles: Role of thermal, radiation damping and encapsulating shell at various excitation pressures","A simple generalized model (GM) for coated bubbles accounting for the effect
+of compressibility of the liquid is presented. The GM was then coupled with
+nonlinear ODEs that account for the thermal effects. Starting with mass and
+momentum conservation equations for a bubbly liquid and using the GM, nonlinear
+pressure dependent terms were derived for energy dissipation due to thermal
+damping (Td), radiation damping (Rd) and dissipation due to the viscosity of
+liquid (Ld) and coating (Cd). The dissipated energies were solved for uncoated
+and coated 2- 20 $\mu m$ bubbles over a frequency range of $0.25f_r-2.5f_r$
+($f_r$ is the bubble resonance) and for various acoustic pressures
+(1kPa-300kPa). Thermal effects were examined for air and C3F8 gas cores in each
+case. For uncoated bubbles with an air gas core and a diameter larger than 4
+$\mu m$, thermal damping is the strongest damping factor. When pressure
+increases, the contributions of Rd grow faster and become the dominant damping
+mechanism for pressure dependent resonance frequencies (e.g. fundamental and
+super harmonic resonances). For coated bubbles, Cd is the strongest damping
+mechanism. As pressure increases Rd contributes more to damping compared to Ld
+and Td. In case of air bubbles, as pressure increases, the linear thermal model
+largely deviates from the nonlinear model and accurate modeling requires
+inclusion of the full thermal model. However, for coated C3F8 bubbles of
+diameter 1-8 $\mu m$, typically used in medical ultrasound, thermal effects
+maybe neglected even at higher pressures. We show that the scattering to
+damping ratio (STDR), a measure of the effectiveness of the bubble as contrast
+agent, is pressure dependent and can be maximized for specific frequency ranges
+and pressures.",1909.08793v1
+2020-11-20,The effect of magnetic field on the damping of slow waves in the solar corona,"Slow magnetoacoustic waves are routinely observed in astrophysical plasma
+systems such as the solar corona. As a slow wave propagates through a plasma,
+it modifies the equilibrium quantities of density, temperature, and magnetic
+field. In the corona and other plasma systems, the thermal equilibrium is
+comprised of a balance between continuous heating and cooling processes, the
+magnitudes of which vary with density, temperature and magnetic field. Thus the
+wave may induce a misbalance between these competing processes. Its back
+reaction on the wave has been shown to lead to dispersion, and amplification or
+damping, of the wave. In this work the importance of the effect of magnetic
+field in the rapid damping of slow waves in the solar corona by heating/cooling
+misbalance is evaluated and compared to the effects of thermal conduction. The
+two timescales characterising the effect of misbalance are derived and
+calculated for plasma systems with a range of typical coronal conditions. The
+predicted damping times of slow waves from thermal misbalance in the solar
+corona are found to be of the order of 10-100 minutes, coinciding with the wave
+periods and damping times observed. Moreover the slow wave damping by thermal
+misbalance is found to be comparable to the damping by field-aligned thermal
+conduction. We show that in the infinite field limit, the wave dynamics is
+insensitive to the dependence of the heating function on the magnetic field,
+and this approximation is found to be valid in the corona so long as the
+magnetic field strength is greater than 10G for quiescent loops and plumes and
+100G for hot and dense loops. In summary thermal misbalance may damp slow
+magnetoacoustic waves rapidly in much of the corona, and its inclusion in our
+understanding of slow mode damping may resolve discrepancies between
+observations and theory relying on compressive viscosity and thermal conduction
+alone.",2011.10437v1
+1997-11-25,Abundances of Heavy Elements and CO Molecules in High Redshift Damped Lyman-alpha Galaxies,"Damped Lyman-alpha systems seen in spectra of background quasars are
+generally thought to represent high redshift counterparts of present-day
+galaxies. We summarize observations of heavy element abundances in damped
+Lyman-alpha systems. The results of a systematic search for CO and C II*
+absorption in 17 damped Lyman-alpha systems are also presented using
+observations obtained with the 10m Keck telescopes. The latter provides a
+useful constraint on the expected strength of [C II] 158 micron emission from
+damped Lyman-alpha galaxies. It is hoped that these results will be useful for
+planning future radio to millimeter wave observations of high redshift galaxies
+using next generation instruments which are now being built.",9711298v1
+1997-12-05,Magnetohydrodynamics in the Early Universe and the Damping of Non-linear Alfven Waves,"The evolution and viscous damping of cosmic magnetic fields in the early
+universe, is analysed. Using the fact that the fluid, electromagnetic, and
+shear viscous energy-momentum tensors are all conformally invariant, the
+evolution is transformed from the expanding universe setting into that in flat
+spacetime. Particular attention is paid to the evolution of nonlinear Alfven
+modes. For a small enough magnetic field, which satisfies our observational
+constraints, these wave modes either oscillate negligibly or, when they do
+oscillate, become overdamped. Hence they do not suffer Silk damping on galactic
+and subgalactic scales. The smallest scale which survives damping depends on
+the field strength and is of order a dimensionless Alfven velocity times the
+usual baryon-photon Silk damping scale. After recombination, nonlinear effects
+can convert the Alfven mode into compressional, gravitationally unstable waves
+and seed cosmic structures if the cosmic magnetic field is sufficiently strong.",9712083v1
+2001-08-09,Are Simulations of CDM Consistent with Galactic-Scale Observations at High Redshift?,"We compare new observations on the kinematic characteristics of the damped
+Lya systems against results from numerical SPH simulations to test the
+predictions of hierarchical galaxy formation. This exercise is particularly
+motivated by recent numerical results on the cross-section of damped Lya
+systems. Our analysis focuses on the velocity widths of ~50 low-ion absorption
+profiles from our sample of z>1.5 damped Lya systems. The results indicate that
+current numerical simulations fail to match the damped Lya observations at high
+confidence levels (>99.9%). Although we do not believe that our results present
+an insurmountable challenge to the paradigm of hierarchical cosmology, the
+damped Lya observations suggest that current numerical SPH simulations overlook
+an integral aspect of galaxy formation.",0108154v1
+2003-03-19,Distinct Abundance Patterns in Multiple Damped Ly-alpha Galaxies: Evidence for Truncated Star Formation?,"(abridged) Following our previous work on metal abundances of a double damped
+Ly-alpha system with a line-of-sight separation ~2000 km/s (Ellison & Lopez
+2001), we present VLT UVES abundances of 3 new systems spanning a total of
+\~6000 km/s at z~2.5 toward the southern QSO CTQ247. These abundances are
+supplemented with echelle observations of another `double' damped Ly-alpha
+system in the literature. We propose a definition in terms of velocity shift of
+the sub-class 'multiple damped Ly-alpha system', which is motivated by its
+possible connection with large-scale structure. We find that the abundance
+ratio alpha/Fe is systematically low in multiple systems compared with single
+systems, and with a small scatter. The same behavior is found in 2 more single
+DLA systems taken from the literature that show evidence of belonging to a
+galaxy group. After a careful investigation of possible sources of systematic
+errors, we conclude that the low alpha/Fe ratios in multiple DLAs have a
+nucleosynthetic origin. We suggest that they could be explained by reduced star
+formation in multiple damped Ly-alpha systems, possibly due to environmental
+effects.",0303441v1
+2003-05-16,New Damped Lya Metallicities from ESI Spectroscopy of Five Palomar Sky Survey Quasars,"This paper presents chemical abundance measurements for 12 new z>3 damped Lya
+systems discovered toward five quasars from the Palomar Sky Survey. We
+determine HI column densities from profile fits to the observed damped Lya
+profiles and measure ionic column densities and limits for all observed
+metal-line transitions. This dataset, acquired with the Echellette Spectrograph
+and Imager on the KeckII telescope, adds to the rapidly growing database of
+damped Lya abundances. It will impact studies of chemical evolution in the
+early universe and help identify candidates for detailed follow-up observations
+with echelle spectrographs. We report the discovery of the first quasar
+sightline with four cosmologically distinct damped Lya systems.",0305313v1
+2006-07-06,Ekman layer damping of r-modes revisited,"We investigate the damping of neutron star r-modes due to the presence of a
+viscous boundary (Ekman) layer at the interface between the crust and the core.
+Our study is motivated by the possibility that the gravitational-wave driven
+instability of the inertial r-modes may become active in rapidly spinning
+neutron stars, eg. in low-mass X-ray binaries, and the fact that a viscous
+Ekman layer at the core-crust interface provides an efficient damping mechanism
+for these oscillations. We review various approaches to the problem and carry
+out an analytic calculation of the effects due to the Ekman layer for a rigid
+crust. Our analytic estimates support previous numerical results, and provide
+further insight into the intricacies of the problem. We add to previous work by
+discussing the effect that compressibility and composition stratification have
+on the boundary layer damping. We show that, while stratification is
+unimportant for the r-mode problem, composition suppresses the damping rate by
+about a factor of two (depending on the detailed equation of state).",0607105v2
+1997-11-05,Hydrodynamic damping in trapped Bose gases,"Griffin, Wu and Stringari have derived the hydrodynamic equations of a
+trapped dilute Bose gas above the Bose-Einstein transition temperature. We give
+the extension which includes hydrodynamic damping, following the classic work
+of Uehling and Uhlenbeck based on the Chapman-Enskog procedure. Our final
+result is a closed equation for the velocity fluctuations $\delta v$ which
+includes the hydrodynamic damping due to the shear viscosity $\eta$ and the
+thermal conductivity $\kappa$. Following Kavoulakis, Pethick and Smith, we
+introduce a spatial cutoff in our linearized equations when the density is so
+low that the hydrodynamic description breaks down. Explicit expressions are
+given for $\eta$ and $\kappa$, which are position-dependent through dependence
+on the local fugacity when one includes the effect of quantum degeneracy of the
+trapped gas. We also discuss a trapped Bose-condensed gas, generalizing the
+work of Zaremba, Griffin and Nikuni to include hydrodynamic damping due to the
+(non-condensate) normal fluid.",9711036v4
+1998-05-01,Finite Temperature Perturbation Theory for a Spatially Inhomogeneous Bose-condensed Gas,"We develop a finite temperature perturbation theory (beyond the mean field)
+for a Bose-condensed gas and calculate temperature-dependent damping rates and
+energy shifts for Bogolyubov excitations of any energy. The theory is
+generalized for the case of excitations in a spatially inhomogeneous (trapped)
+Bose-condensed gas, where we emphasize the principal importance of
+inhomogeneouty of the condensate density profile and develop the method of
+calculating the self-energy functions. The use of the theory is demonstrated by
+calculating the damping rates and energy shifts of low-energy quasiclassical
+excitations, i.e. the quasiclassical excitations with energies much smaller
+than the mean field interaction between particles. In this case the boundary
+region of the condensate plays a crucial role, and the result for the damping
+rates and energy shifts is completely different from that in spatially
+homogeneous gases. We also analyze the frequency shifts and damping of sound
+waves in cylindrical Bose condensates and discuss the role of damping in the
+recent MIT experiment on the sound propagation.",9805015v2
+2003-10-18,Experiment and Dynamic Simulations of Radiation Damping of Laser-polarized liquid 129Xe at low magnetic field in a flow system,"Radiation damping is generally observed when the sample with high spin
+concentration and high gyro-magnetic ratio is placed in a high magnetic field.
+However, we firstly observed liquid state 129Xe radiation damping using
+laser-enhanced nuclear polarization at low magnetic field in a flow system in
+which the polarization enhancement factor for the liquid state 129Xe was
+estimated to be 5000, and furthermore theoretically simulated the envelopes of
+the 129Xe FID and spectral lineshape in the presence of both relaxation and
+radiation damping with different pulse flip angles and ratios of T2*/Trd. The
+radiation damping time constant Trd of 5 ms was derived based on the
+simulations. The reasons of depolarization and the further possible
+improvements were also discussed.",0310435v1
+2004-03-25,XMCD characterization of rare-earth dopants in Ni$_{81}$Fe$_{19}$(50nm): microscopic basis of engineered damping,"We present direct evidence for the contribution of local orbital moments to
+the damping of magnetization precession in magnetic thin films. Using x-ray
+magnetic circular dichroism (XMCD) characterization of rare-earth (RE)
+M$_{4,5}$ edges in Ni$_{81}$Fe$_{19}$ doped with $<$ 2% Gd and Tb, we show that
+the enhancement of GHz precessional relaxation is accompanied by a significant
+orbital moment fraction on the RE site. Tb impurities, which enhance the
+Landau-Lifshitz(-Gilbert) LL(-G) damping $\lambda(\alpha)$, show a spin to
+orbital number ratio of 1.5$\pm$0.3; Gd impurities, which have no effect on
+damping, show a spin to orbital number ratio of zero within experimental error.
+The results indicate that the dopant-based control of magnetization damping in
+RE-doped ferromagnets is an atomistic effect, arising from spin-lattice
+coupling, and thus scalable to nanometer dimensions.",0403627v1
+2005-02-08,Landau Damping of Spin Waves in Trapped Boltzmann Gases,"A semiclassical method is used to study Landau damping of transverse
+pseudo-spin waves in harmonically trapped ultracold gases in the collisionless
+Boltzmann limit. In this approach, the time evolution of a spin is calculated
+numerically as it travels in a classical orbit through a spatially dependent
+mean field. This method reproduces the Landau damping results for spin-waves in
+unbounded systems obtained with a dielectric formalism. In trapped systems, the
+simulations indicate that Landau damping occurs for a given spin-wave mode
+because of resonant phase space trajectories in which spins are ""kicked out"" of
+the mode (in spin space). A perturbative analysis of the resonant and nearly
+resonant trajectories gives the Landau damping rate, which is calculated for
+the dipole and quadrupole modes as a function of the interaction strength. The
+results are compared to a numerical solution of the kinetic equation by Nikuni
+et al.",0502189v1
+2005-06-01,Landau damping of Bogoliubov excitations in optical lattices at finite temperature,"We study the damping of Bogoliubov excitations in an optical lattice at
+finite temperatures. For simplicity, we consider a Bose-Hubbard tight-binding
+model and limit our analysis to the lowest excitation band. We use the Popov
+approximation to calculate the temperature dependence of the number of
+condensate atoms $n^{\rm c 0}(T)$ in each lattice well. We calculate the Landau
+damping of a Bogoliubov excitation in an optical lattice due to coupling to a
+thermal cloud of excitations. While most of the paper concentrates on 1D
+optical lattices, we also briefly present results for 2D and 3D lattices. For
+energy conservation to be satisfied, we find that the excitations in the
+collision process must exhibit anomalous dispersion ({\it i.e.} the excitation
+energy must bend upward at low momentum), as also exhibited by phonons in
+superfluid $^4\rm{He}$. This leads to the sudden disappearance of all damping
+processes in $D$-dimensional simple cubic optical lattice when $U n^{\rm c
+0}\ge 6DJ$, where $U$ is the on-site interaction, and $J$ is the hopping matrix
+element. Beliaev damping in a 1D optical lattice is briefly discussed.",0506016v1
+2006-06-15,Landau damping: instability mechanism of superfluid Bose gases moving in optical lattices,"We investigate Landau damping of Bogoliubov excitations in a dilute Bose gas
+moving in an optical lattice at finite temperatures. Using a 1D tight-binding
+model, we explicitly obtain the Landau damping rate, the sign of which
+determines the stability of the condensate. We find that the sign changes at a
+certain condensate velocity, which is exactly the same as the critical velocity
+determined by the Landau criterion of superfluidity. This coincidence of the
+critical velocities reveals the microscopic mechanism of the Landau
+instability. This instability mechanism is also consistent with the recent
+experiment suggesting that a thermal cloud plays a crucial role in breakdown of
+superfluids, since the thermal cloud is also vital in the Landau damping
+process. We also examine the possibility of simultaneous disappearance of all
+damping processes.",0606398v2
+1996-11-25,Damping rates of hard momentum particles in a cold ultrarelativistic plasma,"We compute the damping rates of one-particle excitations in a cold
+ultrarelativistic plasma to leading order in the coupling constant e for three
+types of interaction: Yukawa coupling to a massless scalar boson, QED and QCD.
+Damping rates of charged particles in QED and QCD are of order e^3 mu, while
+damping rates of other particles are of order e^4 mu or e^4 mu log(1/e). We
+find that the damping rate of an electron or of a quark is constant far from
+the Fermi surface, and decreases linearly with the excitation energy close to
+the Fermi surface. This unusual behavior is attributed to the long-range
+magnetic interactions.",9611415v2
+1999-09-24,Gauge Invariance of Nonlinear Landau Damping Rate of Bose Excitations in Quark-Gluon Plasma,"On the basis of the approximate dynamical equations describing the behavior
+of quark-gluon plasma (QGP) in the semiclassical limit and Yang-Mills equation,
+the kinetic equation for longitudinal waves (plasmons) is obtained. With the
+Ward identities the gauge invariance of obtained nonlinear Landau damping rate
+is proved. The physical mechanisms defining nonlinear scattering of a plasmon
+by QGP particles are analyzed. The problem on a connection of nonlinear Landau
+damping rate of longitudinal oscillations with damping rate, obtained in the
+framework of hard thermal loops approximation, is considered. It is shown that
+the gauge-dependent part of nonlinear Landau damping rate for the plasmons with
+zero momentum vanishes on mass-shell.",9909505v1
+2005-07-16,Sharp estimates for the number of degrees of freedom for the damped-driven 2D Navier--Stokes equations,"We derive upper bounds for the number of asymptotic degrees (determining
+modes and nodes) of freedom for the two-dimensional Navier--Stokes system and
+Navier-Stokes system with damping. In the first case we obtain the previously
+known estimates in an explicit form, which are larger than the fractal
+dimension of the global attractor. However, for the Navier--Stokes system with
+damping our estimates for the number of the determining modes and nodes are
+comparable to the sharp estimates for the fractal dimension of the global
+attractor. Our investigation of the damped-driven 2D Navier--Stokes system is
+inspired by the Stommel--Charney barotropic model of ocean circulation where
+the damping represents the Rayleigh friction. We remark that our results
+equally apply to the Stommel--Charney model.",0507327v1
+2006-12-04,A singular perturbation approach for choosing PageRank damping factor,"The choice of the PageRank damping factor is not evident. The Google's choice
+for the value c=0.85 was a compromise between the true reflection of the Web
+structure and numerical efficiency. However, the Markov random walk on the
+original Web Graph does not reflect the importance of the pages because it
+absorbs in dead ends. Thus, the damping factor is needed not only for speeding
+up the computations but also for establishing a fair ranking of pages. In this
+paper, we propose new criteria for choosing the damping factor, based on the
+ergodic structure of the Web Graph and probability flows. Specifically, we
+require that the core component receives a fair share of the PageRank mass.
+Using singular perturbation approach we conclude that the value c=0.85 is too
+high and suggest that the damping factor should be chosen around 1/2. As a
+by-product, we describe the ergodic structure of the OUT component of the Web
+Graph in detail. Our analytical results are confirmed by experiments on two
+large samples of the Web Graph.",0612079v1
+1998-10-26,Microscopic Structure of Rotational Damping,"The damping of collective rotational motion is studied microscopically,
+making use of shell model calculations based on the cranked Nilsson deformed
+mean-field and on residual two-body interactions, and focusing on the shape of
+the gamma-gamma correlation spectra and on its systematic behavior. It is shown
+that the spectral shape is directly related to the damping width of collective
+rotation, \Gammarot, and to the spreading width of many-particle many-hole
+configurations, \Gammamu. The rotational damping width is affected by the shell
+structure, and is very sensitive to the position of the Fermi surface, besides
+mass number, spin and deformation. This produces a rich variety of features in
+the rotational damping phenomena.",9810066v1
+2004-07-25,Rotational damping in a multi-$j$ shell particles-rotor model,"The damping of collective rotational motion is investigated by means of
+particles-rotor model in which the angular momentum coupling is treated exactly
+and the valence nucleons are in a multi-$j$ shell mean-field. It is found that
+the onset energy of rotational damping is around 1.1 MeV above yrast line, and
+the number of states which form rotational band structure is thus limited. The
+number of calculated rotational bands around 30 at a given angular momentum
+agrees qualitatively with experimental data. The onset of rotational damping
+takes place gradually as a function of excitation energy. It is shown that the
+pairing correlation between valence nucleons has a significant effect on the
+appearance of rotational damping.",0407089v3
+2001-07-19,Manifold Damping of Transverse Wakefields in High Phase Advance Traveling Wave Structures and Local Damping of Dipole Wakefields in Standing Wave Accelerators,"Operating the SLAC/KEK DDS (Damped Detuned Structure) X-band linacs at high
+gradients (in excess of 70MV/m) has recently been found to be limited by the
+accelerator structures breaking down and as a consequence severe damage occurs
+to the cells which makes the structures inoperable. A series of recent
+experiments at SLAC indicates that arcing in the structures is significantly
+reduced if the group velocity of the accelerating mode is reduced and
+additionally it has been discovered that reducing the length of the
+accelerating structure also limits the number and intensity of breakdown events
+[1]. However, in designing new accelerating structures care must be taken to
+ensure that the beam-induced transverse wakefields do not cause the beam to
+become unstable. Here, we report on damping transverse wakefields in two
+different short structures: a 90cm traveling wave structure in which the
+wakefield is coupled out to four attached manifolds and secondly, in a standing
+wave structure in which a limited number of cells heavily damp down the
+wakefield.
+  [1] C. Adolphsen, ROAA003, this conf.",0107048v1
+2002-06-28,Manifold Damping Of Wakefields In High Phase Advance Linacs For The NLC,"Earlier RDDS (Rounded Damped Detuned Structures) [1,2], designed, fabricated
+and tested at SLAC, in collaboration with KEK, have been shown to damp
+wakefields successfully. However, electrical breakdown has been found to occur
+in these structures and this makes them inoperable at the desired gradient.
+Recent results [3] indicate that lowering the group velocity of the
+accelerating mode reduces electrical breakdown events. In order to preserve the
+filling time of each structure a high synchronous phase advance (150 degrees as
+opposed to 120 used in previous NLC designs) has been chosen. Here, damping of
+the wakefield is analyzed. Manifold damping and interleaving of structure cell
+frequencies is discussed. These wakefields impose alignment tolerances on the
+cells and on the structure as a whole. Tolerance calculations are performed and
+these are compared with analytic estimations.",0206090v1
+2006-06-30,Nonlinear Damping of the LC Circuit using Anti-parallel Diodes,"We investigate a simple variation of the series RLC circuit in which
+anti-parallel diodes replace the resistor. This results in a damped harmonic
+oscillator with a nonlinear damping term that is maximal at zero current and
+decreases with an inverse current relation for currents far from zero. A set of
+nonlinear differential equations for the oscillator circuit is derived and
+integrated numerically for comparison with circuit measurements. The agreement
+is very good for both the transient and steady-state responses. Unlike the
+standard RLC circuit, the behavior of this circuit is amplitude dependent. In
+particular for the transient response the oscillator makes a transition from
+under-damped to over-damped behavior, and for the driven oscillator the
+resonance response becomes sharper and stronger as drive source amplitude
+increases. The equipment is inexpensive and common to upper level physics labs.",0606261v1
+1995-11-11,A New Look at the Landau's Theory of Spreading and Damping of Waves in Collisionless Plasmas,"The theory of plasma waves and Landau damping in Maxwellian plasmas, Landau's
+``rule of pass around poles'' include doubtful statements, particularly related
+to an artificial ``constructing'' of the dispersion equation, what should allow
+the possibility of its solution otherwise not existing at all, and the
+possibility of analytical continuations of corresponding very specific ruptured
+functions in the one-dimensional Laplace transformation, used by Landau, what
+is the base of his theory.
+  We represent, as an accessible variant, a more general alternative theory
+based on a two-dimensional Laplace transformation, leading to an asymptotical
+in time and space solution as a complicated superposition of coupled damping
+and {\em non-damping \/} plane waves and oscillations with different dispersion
+laws for every constituent mode. This theory naturally and very simply explains
+paradoxes of the phenomenon of plasma echo. We propose for discussion a new
+ideology of plasma waves (both electron and ion-acoustic waves) qualitatively
+different from the traditional theory of Landau damping for non-collisional as
+well as for low-collisional plasmas.",9511001v1
+2001-07-27,Quantum limits of cold damping with optomechanical coupling,"Thermal noise of a mirror can be reduced by cold damping. The displacement is
+measured with a high-finesse cavity and controlled with the radiation pressure
+of a modulated light beam. We establish the general quantum limits of noise in
+cold damping mechanisms and we show that the optomechanical system allows to
+reach these limits. Displacement noise can be arbitrarily reduced in a narrow
+frequency band. In a wide-band analysis we show that thermal fluctuations are
+reduced as with classical damping whereas quantum zero-point fluctuations are
+left unchanged. The only limit of cold damping is then due to zero-point energy
+of the mirror",0107138v2
+2005-05-20,A symmetric treatment of damped harmonic oscillator in extended phase space,"Extended phase space (EPS) formulation of quantum statistical mechanics
+treats the ordinary phase space coordinates on the same footing and thereby
+permits the definite the canonical momenta conjugate to these coordinates . The
+extended lagrangian and extended hamiltonian are defined in EPS by the same
+procedure as one does for ordinary lagrangian and hamiltonian. The combination
+of ordinary phase space and their conjugate momenta exhibits the evolution of
+particles and their mirror images together. The resultant evolution equation in
+EPS for a damped harmonic oscillator, is such that the energy dissipated by the
+actual oscillator is absorbed in the same rate by the image oscillator leaving
+the whole system as a conservative system. We use the EPS formalism to obtain
+the dual hamiltonian of a damped harmonic oscillator, first proposed by
+Batemann, by a simple extended canonical transformations in the extended phase
+space. The extended canonical transformations are capable of converting the
+damped system of actual and image oscillators to an undamped one, and transform
+the evolution equation into a simple form. The resultant equation is solved and
+the eigenvalues and eigenfunctions for damped oscillator and its mirror image
+are obtained. The results are in agreement with those obtained by Bateman. At
+last, the uncertainty relation are examined for above system.",0505147v1
+2007-08-28,Pattern formation in the damped Nikolaevskiy equation,"The Nikolaevskiy equation has been proposed as a model for seismic waves,
+electroconvection and weak turbulence; we show that it can also be used to
+model transverse instabilities of fronts. This equation possesses a large-scale
+""Goldstone"" mode that significantly influences the stability of spatially
+periodic steady solutions; indeed, all such solutions are unstable at onset,
+and the equation exhibits so-called soft-mode turbulence. In many applications,
+a weak damping of this neutral mode will be present, and we study the influence
+of this damping on solutions to the Nikolaevskiy equation. We examine the
+transition to the usual Eckhaus instability as the damping of the large-scale
+mode is increased, through numerical calculation and weakly nonlinear analysis.
+The latter is accomplished using asymptotically consistent systems of coupled
+amplitude equations. We find that there is a critical value of the damping
+below which (for a given value of the supercriticality parameter) all periodic
+steady states are unstable. The last solutions to lose stability lie in a cusp
+close to the left-hand side of the marginal stability curve.",0708.3735v1
+2008-01-12,Strong and weak coupling limits in optics of quantum well excitons,"A transition between the strong (coherent) and weak (incoherent) coupling
+limits of resonant interaction between quantum well (QW) excitons and bulk
+photons is analyzed and quantified as a function of the incoherent damping rate
+caused by exciton-phonon and exciton-exciton scattering. For confined QW
+polaritons, a second, anomalous, damping-induced dispersion branch arises and
+develops with increasing damping. In this case, the strong-weak coupling
+transition is attributed to a critical damping rate, when the intersection of
+the normal and damping-induced dispersion branches occurs. For the radiative
+states of QW excitons, i.e., for radiative QW polaritons, the transition is
+described as a qualitative change of the photoluminescence spectrum at grazing
+angles along the QW structure. Furthermore, we show that the radiative
+corrections to the QW exciton states with in-plane wavevector approaching the
+photon cone are universally scaled by an energy parameter rather than diverge.
+The strong-weak coupling transition rates are also proportional to the same
+energy parameter. The numerical evaluations are given for a GaAs single quantum
+well with realistic parameters.",0801.1895v2
+2008-01-22,Damped Bloch Oscillations of Bose-Einstein Condensates in Disordered Potential Gradients,"We investigate both experimentally and theoretically disorder induced damping
+of Bloch oscillations of Bose-Einstein condensates in optical lattices. The
+spatially inhomogeneous force responsible for the damping is realised by a
+combination of a disordered optical and a magnetic gradient potential. We show
+that the inhomogeneity of this force results in a broadening of the
+quasimomentum spectrum, which in turn causes damping of the centre-of-mass
+oscillation. We quantitatively compare the obtained damping rates to the
+simulations using the Gross-Pitaevskii equation. Our results are relevant for
+high precision experiments on very small forces, which require the observation
+of a large number of oscillation cycles.",0801.3437v2
+2008-02-26,"Fractional Langevin Equation: Over-Damped, Under-Damped and Critical Behaviors","The dynamical phase diagram of the fractional Langevin equation is
+investigated for harmonically bound particle. It is shown that critical
+exponents mark dynamical transitions in the behavior of the system. Four
+different critical exponents are found. (i) $\alpha_c=0.402\pm 0.002$ marks a
+transition to a non-monotonic under-damped phase, (ii) $\alpha_R=0.441...$
+marks a transition to a resonance phase when an external oscillating field
+drives the system, (iii) $\alpha_{\chi_1}=0.527...$ and (iv)
+$\alpha_{\chi_2}=0.707...$ marks transition to a double peak phase of the
+""loss"" when such an oscillating field present. As a physical explanation we
+present a cage effect, where the medium induces an elastic type of friction.
+Phase diagrams describing over-damped, under-damped regimes, motion and
+resonances, show behaviors different from normal.",0802.3777v1
+2008-04-26,Vibrational modes of metal nanoshells and bimetallic core-shell nanoparticles,"We study theoretically spectrum of radial vibrational modes in composite
+metal nanostructures such as bimetallic core-shell particles and metal
+nanoshells with dielectric core in an environment. We calculate frequencies and
+damping rates of fundamental (breathing) modes for these nanostructures along
+with those of two higher-order modes. For metal nanoshells, we find that the
+breathing mode frequency is always lower than the one for solid particles of
+the same size, while the damping is higher and increases with reduction of the
+shell thickness. We identify two regimes that can be characterized as weakly
+damped and overdamped vibrations in the presence of external medium. For
+bimetalllic particles, we find periodic dependence of frequency and damping
+rate on the shell thickness with period determined by mode number. For both
+types of nanostructures, the frequency of higher modes is nearly independent of
+the environment, while the damping rate shows strong sensitivity to outside
+medium.",0804.4249v2
+2008-09-26,Damping of the baryon acoustic oscillations in the matter power spectrum as a probe of the growth factor,"We investigate the damping of the baryon acoustic oscillations (BAO)
+signature in the matter power spectrum due to the quasi-nonlinear clustering of
+density perturbations. On the basis of the third order perturbation theory, we
+construct a fitting formula of the damping in an analytic way. This
+demonstrates that the damping is closely related with the growth factor and the
+amplitude of the matter power spectrum. Then, we investigate the feasibility of
+constraining the growth factor through a measurement of the damping of the BAO
+signature. An extension of our formula including higher order corrections of
+density perturbations is also discussed.",0809.4538v2
+2008-10-07,Corotational Damping of Diskoseismic C-modes in Black Hole Accretion Discs,"Diskoseismic c-modes in accretion discs have been invoked to explain
+low-frequency variabilities observed in black-hole X-ray binaries. These modes
+are trapped in the inner-most region of the disc and have frequencies much
+lower than the rotation frequency at the disc inner radius. We show that
+because the trapped waves can tunnel through the evanescent barrier to the
+corotational wave zone, the c-modes are damped due to wave absorption at the
+corotation resonance. We calculate the corotational damping rates of various
+c-modes using the WKB approximation. The damping rate varies widely depending
+on the mode frequency, the black hole spin parameter and the disc sound speed,
+and is generally much less than 10% of the mode frequency. A sufficiently
+strong excitation mechanism is needed to overcome this corotational damping and
+make the mode observable.",0810.1299v3
+2008-10-10,Non-standard conserved Hamiltonian structures in dissipative/damped systems : Nonlinear generalizations of damped harmonic oscillator,"In this paper we point out the existence of a remarkable nonlocal
+transformation between the damped harmonic oscillator and a modified Emden type
+nonlinear oscillator equation with linear forcing, $\ddot{x}+\alpha
+x\dot{x}+\beta x^3+\gamma x=0,$ which preserves the form of the time
+independent integral, conservative Hamiltonian and the equation of motion.
+Generalizing this transformation we prove the existence of non-standard
+conservative Hamiltonian structure for a general class of damped nonlinear
+oscillators including Li\'enard type systems. Further, using the above
+Hamiltonian structure for a specific example namely the generalized modified
+Emden equation $\ddot{x}+\alpha x^q\dot{x}+\beta x^{2q+1}=0$, where $\alpha$,
+$\beta$ and $q$ are arbitrary parameters, the general solution is obtained
+through appropriate canonical transformations. We also present the conservative
+Hamiltonian structure of the damped Mathews-Lakshmanan oscillator equation. The
+associated Lagrangian description for all the above systems is also briefly
+discussed.",0810.1819v2
+2008-11-05,R-matrix inner-shell electron-impact excitation of Fe$^{15+}$ including Auger-plus-radiation damping,"We present results for the inner-shell electron-impact excitation of
+Fe$^{15+}$ using the intermediate-coupling frame transformation {\it R}-matrix
+approach in which Auger-plus-radiation damping has been included. The target
+and close-coupling expansions are both taken to be the 134 levels belonging to
+the configurations ${\rm 2s^22p^63}l$, ${\rm 2s^22p^53s3}l$, ${\rm
+2s^22p^53p^2}$ and ${\rm 2s^22p^53p3d}$. The comparison of Maxwell-averaged
+effective collision strengths with and without damping shows that the damping
+reduction is about 30-40% for many transitions at low temperatures, but up to
+80% for a few transitions. As a consequence, the results of previous Dirac
+$R$-matrix calculations (Aggarwal and Keenan, 2008) overestimate the effective
+collision strengths due to their omission of Auger-plus-radiation damping.",0811.0750v1
+2009-03-11,An alternate design for CLIC main linac wakefield suppression,"The present design of the main accelerating structure for CLIC is based on
+heavy damping (WDS) with a Q of ~10. The wakefield suppression in this case
+entails locating the damping materials in relatively close proximity to the
+accelerating cells. Herein we present an alternate design for the main
+accelerating structures. We detune the lowest dipole band by prescribing a
+Gaussian distribution to the cell parameters and consider moderate damping
+Q~500 to prevent the recoherence of the modes; in this case the damping
+materials can be located at an extended distance from the accelerating
+structure. The procedure to achieve a well-damped wakefield is described.
+Results are presented elucidating the various designs including the current one
+which is being developed to incorporate r.f. breakdown, pulse surface heating
+and beam dynamics constraints.",0903.1935v1
+2009-04-17,Revealing Sub-Surface Vibrational Modes by Atom-Resolved Damping Force Spectroscopy,"We propose to use the damping signal of an oscillating cantilever in dynamic
+atomic force microscopy as a noninvasive tool to study the vibrational
+structure of the substrate. We present atomically resolved maps of damping in
+carbon nanotube peapods, capable of identifying the location and packing of
+enclosed Dy@C82 molecules as well as local excitations of vibrational modes
+inside nanotubes of different diameter. We elucidate the physical origin of
+damping in a microscopic model and provide quantitative interpretation of the
+observations by calculating the vibrational spectrum and damping of Dy@C82
+inside nanotubes with different diameters using ab initio total energy and
+molecular dynamics calculations.",0904.2666v1
+2009-08-04,Time domain detection of pulsed spin torque damping reduction,"Combining multiple ultrafast spin torque impulses with a 5 nanosecond
+duration pulse for damping reduction, we observe time-domain precession which
+evolves from an initial 1 ns duration transient with changing precessional
+amplitude to constant amplitude oscillations persisting for over 2 ns. These
+results are consistent with relaxation of the transient trajectories to a
+stable orbit with nearly zero damping. We find that in order to observe
+complete damping cancellation and the transient behavior in a time domain
+sampling measurement, a short duration, fast rise-time pulse is required to
+cancel damping without significant trajectory dephasing.",0908.0481v1
+2009-10-02,Damping of a nanomechanical oscillator strongly coupled to a quantum dot,"We present theoretical and experimental results on the mechanical damping of
+an atomic force microscope cantilever strongly coupled to a self-assembled InAs
+quantum dot. When the cantilever oscillation amplitude is large, its motion
+dominates the charge dynamics of the dot which in turn leads to nonlinear,
+amplitude-dependent damping of the cantilever. We observe highly asymmetric
+lineshapes of Coulomb blockade peaks in the damping that reflect the degeneracy
+of energy levels on the dot, in excellent agreement with our strong coupling
+theory. Furthermore, we predict that excited state spectroscopy is possible by
+studying the damping versus oscillation amplitude, in analogy to varying the
+amplitude of an ac gate voltage.",0910.0308v1
+2010-01-27,The spatial damping of magnetohydrodynamic waves in a flowing partially ionised prominence plasma,"Solar prominences are partially ionised plasmas displaying flows and
+oscillations. These oscillations show time and spatial damping and, commonly,
+have been explained in terms of magnetohydrodynamic (MHD) waves. We study the
+spatial damping of linear non-adiabatic MHD waves in a flowing partially
+ionised plasma, having prominence-like physical properties. We consider single
+fluid equations for a partially ionised hydrogen plasma including in the energy
+equation optically thin radiation, thermal conduction by electrons and
+neutrals, and heating. Keeping the frequency real and fixed, we have solved the
+obtained dispersion relations for the complex wavenumber, k, and have analysed
+the behaviour of the damping length, wavelength and the ratio of the damping
+length to the wavelength, versus period, for Alfven, fast, slow and thermal
+waves.",1001.4962v1
+2010-03-04,Internal dissipation of a polymer,"The dynamics of flexible polymer molecules are often assumed to be governed
+by hydrodynamics of the solvent. However there is considerable evidence that
+internal dissipation of a polymer contributes as well. Here we investigate the
+dynamics of a single chain in the absence of solvent to characterize the nature
+of this internal friction. We model the chains as freely hinged but with
+localized bond angles and 3-fold symmetric dihedral angles. We show that the
+damping is close but not identical to Kelvin damping, which depends on the
+first temporal and second spatial derivative of monomer position. With no
+internal potential between monomers, the magnitude of the damping is small for
+long wavelengths and weakly damped oscillatory time dependent behavior is seen
+for a large range of spatial modes. When the size of the internal potential is
+increased, such oscillations persist, but the damping becomes larger. However
+underdamped motion is present even with quite strong dihedral barriers for long
+enough wavelengths.",1003.0944v2
+2010-05-26,Indirect Evidence for Lévy Walks in Squeeze Film Damping,"Molecular flow gas damping of mechanical motion in confined geometries, and
+its associated noise, is important in a variety of fields, including precision
+measurement, gravitational wave detection, and MEMS devices. We used two
+torsion balance instruments to measure the strength and distance-dependence of
+`squeeze film' damping. Measured quality factors derived from free decay of
+oscillation are consistent with gas particle superdiffusion in L\'evy walks and
+inconsistent with those expected from traditional Gaussian random walk particle
+motion. The distance-dependence of squeeze film damping observed in our
+experiments is in agreement with a parameter-free Monte Carlo simulation. The
+squeeze film damping of the motion of a plate suspended a distance d away from
+a parallel surface scales with a fractional power between 1/d and 1/d^2.",1005.4926v2
+2010-05-28,Gravitational wave asteroseismology with fast rotating neutron stars,"We investigate damping and growth times of the f-mode for rapidly rotating
+stars and a variety of different polytropic equations of state in the Cowling
+approximation. We discuss the differences in the eigenfunctions of co- and
+counterrotating modes and compute the damping times of the f-mode for several
+EoS and all rotation rates up to the Kepler-limit. This is the first study of
+the damping/growth time of this type of oscillations for fast rotating neutron
+stars in a general relativistic framework. We use these frequencies and
+damping/growth times to create robust empirical formulae which can be used for
+gravitational wave asteroseismology. The estimation of the damping/growth time
+is based on the quadrupole formula and our results agree very well with
+Newtonian ones in the appropriate limit.",1005.5228v3
+2010-06-09,Synchrotron oscillation damping due to beam-beam collisions,"In DA{\Phi}NE, the Frascati e+/e- collider, the crab waist collision scheme
+has been successfully implemented in 2008 and 2009. During the collision
+operations for Siddharta experiment, an unusual synchrotron damping effect has
+been observed. Indeed, with the longitudinal feedback switched off, the
+positron beam becomes unstable with beam currents in the order of 200-300 mA.
+The longitudinal instability is damped by bringing the positron beam in
+collision with a high current electron beam (~2A). Besides, we have observed a
+shift of \approx 600Hz in the residual synchrotron sidebands. Precise
+measurements have been performed by using both a commercial spectrum analyzer
+and the diagnostics capabilities of the DA{\Phi}NE longitudinal bunch-by-bunch
+feedback. This damping effect has been observed in DA{\Phi}NE for the first
+time during collisions with the crab waist scheme. Our explanation is that beam
+collisions with a large crossing angle produce a longitudinal tune shift and a
+longitudinal tune spread, providing Landau damping of synchrotron oscillations.",1006.1783v1
+2010-06-30,Landau Damping of Baryon Structure Formation in the Post Reionization Epoch,"It has been suggested by Chen and Lai that the proper description of the
+large scale structure formation of the universe in the post-reionization era,
+which is conventionally characterized via gas hydrodynamics, should include the
+plasma collective effects in the formulation. Specifically, it is the combined
+pressure from the baryon thermal motions and the residual long-range
+electrostatic potentials resulted from the imperfect Debye shielding, that
+fights against the gravitational collapse. As a result, at small-scales the
+baryons would oscillate at the ion-acoustic, instead of the conventional
+neutral acoustic, frequency. In this paper we extend and improve the Chen-Lai
+formulation with the attention to the Landau damping of the ion-acoustic
+oscillations. Since T_e \sim T_i in the post-reionization era, the ion acoustic
+oscillations would inevitably suffer the Landau damping which severely
+suppresses the baryon density spectrum in the regimes of intermediate and high
+wavenumber k. To describe this Landau-damping phenomenon more appropriately, we
+find it necessary to modify the filtering wavenumber k_f in our analysis. It
+would be interesting if our predicted Landau damping of the ion-acoustic
+oscillations can be observed at high redshifts.",1006.5777v1
+2010-07-12,Passive damping of beam vibrations through distributed electric networks and piezoelectric transducers: prototype design and experimental validation,"The aim of this work is two-fold: to design devices for passive electric
+damping of structural vibrations by distributed piezoelectric transducers and
+electric networks, and to experimentally validate the effectiveness of such a
+damping concept. Two different electric networks are employed, namely a purely
+resistive network and an inductive-resistive one. The presented devices can be
+considered as distributed versions of the well-known resistive and resonant
+shunt of a single piezoelectric transducer. The technicalfeasibility and
+damping effectiveness of the proposed novel devices are assessed through the
+construction of an experimental prototype. Experimental results are shown to be
+in very good agreement with theoretical predictions. It is proved that the
+presented technique allows for a substantial reduction in the inductances used
+when compared with those required by the single resonant shunted transducer. In
+particular, it is shown that the required inductance decreases when the number
+of piezoelectric elements is increased. The electric networks are optimized in
+order to reduce forced vibrations close to the first resonance frequency.
+Nevertheless, the damping effectiveness for higher modes is experimentally
+proved. As well as specific results, fundamental theoretical and experimental
+considerations for passive distributed vibration control are provided.",1007.1863v1
+2010-07-23,Highly-damped quasi-normal frequencies for piecewise Eckart potentials,"Highly-damped quasi-normal frequencies are very often of the form omega_n =
+(offset) + i n (gap). We investigate the genericity of this phenomenon by
+considering a model potential that is piecewise Eckart (piecewise
+Poeschl-Teller), and developing an analytic ""quantization condition"" for the
+highly-damped quasi-normal frequencies. We find that this omega_n = (offset) +
+i n (gap) behaviour is generic but not universal, with the controlling feature
+being whether or not the ratio of the rates of exponential falloff in the two
+asymptotic directions is a rational number. These observations are of direct
+relevance to any physical situation where highly-damped quasi-normal modes
+(damped modes) are important --- in particular (but not limited to) to black
+hole physics, both theoretical and observational.",1007.4039v2
+2010-09-23,Asymptotic Spectrum of Kerr Black Holes in the Small Angular Momentum Limit,"We study analytically the highly damped quasinormal modes of Kerr black holes
+in the small angular momentum limit. To check the previous analytic
+calculations in the literature, which use a combination of radial and tortoise
+coordinates, we reproduce all the results using the radial coordinate only.
+According to the earlier calculations, the real part of the highly damped
+quasinormal mode frequency of Kerr black holes approaches zero in the limit
+where the angular momentum goes to zero. This result is not consistent with the
+Schwarzschild limit where the real part of the highly damped quasinormal mode
+frequency is equal to c^3 ln(3)/(8 pi G M). In this paper, our calculations
+suggest that the highly damped quasinormal modes of Kerr black holes in the
+zero angular momentum limit make a continuous transition from the Kerr value to
+the Schwarzschild value. We explore the nature of this transition using a
+combination of analytical and numerical techniques. Finally, we calculate the
+highly damped quasinormal modes of the extremal case in which the topology of
+Stokes/anti-Stokes lines takes a different form.",1009.4632v2
+2010-12-31,Exact Tkachenko modes and their damping in the vortex lattice regime of rapidly rotating bosons,"We have found an exact analytical solution of the Bogoliubov-de Gennes
+equations for the Tkachenko modes of the vortex lattice in the lowest Landau
+level (LLL) in the thermodynamic limit at any momenta and calculated their
+damping rates. At finite temperatures both Beliaev and Landau damping leads to
+momentum independent damping rates in the low-energy limit, which shows that at
+sufficiently low energies Tkachenko modes become strongly damped. We then found
+that the mean square fluctuations of the density grow logarithmically at large
+distances, which indicates that the state is ordered in the vortex lattice only
+on a finite (although exponentially large) distance scale and introduces a
+low-momentum cut-off. Using this circumstance we showed that at finite
+temperatures the one-body density matrix undergoes an exponential decay at
+large distances.",1101.0269v1
+2011-01-20,Decoherence and entanglement degradation of a qubit-qutrit system in non-inertial frames,"We study the effect of decoherence on a qubit-qutrit system under the
+influence of global, local and multilocal decoherence in non-inertial frames.
+We show that the entanglement sudden death can be avoided in non-inertial
+frames in the presence of amplitude damping, depolarizing and phase damping
+channels. However, degradation of entanglement is seen due to Unruh effect. It
+is shown that for lower level of decoherence, the depolarizing channel degrades
+the entanglement more heavily as compared to the amplitude damping and phase
+damping channels. However, for higher values of decoherence parameters,
+amplitude damping channel heavily degrades the entanglement of the hybrid
+system. Further more, no ESD is seen for any value of Rob's acceleration.",1101.3986v1
+2011-10-05,Radiation damping in pulsed Gaussian beams,"We consider the effects of radiation damping on the electron dynamics in a
+Gaussian beam model of a laser field. For high intensities, i.e. with
+dimensionless intensity a0 \gg 1, it is found that the dynamics divide into
+three regimes. For low energy electrons (low initial {\gamma}-factor,
+{\gamma}0) the radiation damping effects are negligible. At higher energies,
+but still at 2{\gamma}0 < a0, the damping alters the final displacement and the
+net energy change of the electron. For 2{\gamma}0 > a0 one is in a regime of
+radiation reaction induced electron capture. This capture is found to be stable
+with respect to the spatial properties of the electron beam and results in a
+significant energy loss of the electrons. In this regime the plane wave model
+of the laser field provides a good description of the dynamics, whereas for
+lower energies the Gaussian beam and plane wave models differ significantly.
+Finally the dynamics are considered for the case of an XFEL field. It is found
+that the significantly lower intensities of such fields inhibits the damping
+effects.",1110.0996v1
+2012-03-28,Analysis of the absorbing layers for the weakly-compressible lattice Boltzmann schemes,"It has been demonstrated that Lattice Boltzmann schemes (LBSs) are very
+efficient for Computational AeroAcoustics (CAA). In order to handle the issue
+of absorbing acoustic boundary conditions for LBS, three kinds of damping terms
+are proposed and added into the right hand sides of the governing equations of
+LBS. From the classical theory, these terms play an important role to absorb
+and minimize the acoustic wave reflections from computational boundaries.
+Meanwhile, the corresponding macroscopic equations with the damping terms are
+recovered for analyzing the macroscopic behaviors of the these damping terms
+and determining the critical absorbing strength. Further, in order to detect
+the dissipation and dispersion behaviors, the linearized LBS with the damping
+terms is derived and analyzed. The dispersive and dissipative properties are
+explored in the wave-number spaces via the Von Neumann analysis. The related
+damping strength critical values and the optimal absorbing term are addressed.
+Finally, some benchmark problems are implemented to assess the theoretical
+results.",1203.6350v1
+2012-04-11,Formation of bremsstrahlung in an absorptive QED/QCD medium,"The radiative energy loss of a relativistic charge in a dense, absorptive
+medium can be affected significantly by damping phenomena. The effect is more
+pronounced for large energies of the charge and/or large damping of the
+radiation. This can be understood in terms of a competition between the
+formation time of bremsstrahlung and a damping time scale. We discuss this
+competition in detail for the absorptive QED and QCD medium, focusing on the
+case in which the mass of the charge is large compared to the in-medium mass of
+the radiation quanta. We identify the regions in energy and parameter space, in
+which either coherence or damping effects are of major importance for the
+radiative energy loss spectrum. We show that damping phenomena can lead to a
+stronger suppression of the spectrum than coherence effects.",1204.2469v2
+2012-06-05,Existence and exponential stability of a damped wave equation with dynamic boundary conditions and a delay term,"In this paper we consider a multi-dimensional wave equation with dynamic
+boundary conditions related to the Kelvin-Voigt damping and a delay term acting
+on the boundary. If the weight of the delay term in the feedback is less than
+the weight of the term without delay or if it is greater under an assumption
+between the damping factor, and the difference of the two weights, we prove the
+global existence of the solutions. Under the same assumptions, the exponential
+stability of the system is proved using an appropriate Lyapunov functional.
+More precisely, we show that even when the weight of the delay is greater than
+the weight of the damping in the boundary conditions, the strong damping term
+still provides exponential stability for the system.",1206.1010v1
+2012-08-27,Analysis of the damped quantum search and its application to the one-dimensional Ising system,"An analysis on the damped quantum search by exploring the rate at which the
+target state is obtained. The results were compared with that of the classical
+search since the standard Grover's algorithm does not give a convergent result
+if the number of target state is unknown. For a large number of target states,
+the classical and the damped quantum search give a similar result. However, for
+intermediate values of the target size the damped quantum search gives a higher
+probability of success than the classical search. Furthermore, we also made an
+analysis on the average number of iterations needed to obtain at least one of
+the target states. As the number of target states is reduced, the damped
+quantum search gives a better result than the classical search. The results
+coincide if the size of target state is comparable to the size of the sample.",1208.5509v1
+2012-10-20,Radiative damping of surface plasmon resonance in spheroidal metallic nanoparticle embedded in a dielectric medium,"The local field approach and kinetic equation method is applied to calculate
+the surface plasmon radiative damping in a spheroidal metal nanoparticle
+embedded in any dielectric media. The radiative damping of the surface plasmon
+resonance as a function of the particle radius, shape, dielectric constant of
+the surrounding medium and the light frequency is studied in detail. It is
+found that the radiative damping grows quadratically with the particle radius
+and oscillates with altering both the particle size and the dielectric constant
+of a surrounding medium. Much attention is paid to the electron
+surface-scattering contribution to the plasmon decay. All calculations of the
+radiative damping are illustrated by examples on the Au and Na nanoparticles.",1210.5647v1
+2012-11-11,Dissipation in relativistic superfluid neutron stars,"We analyze damping of oscillations of general relativistic superfluid neutron
+stars. To this aim we extend the method of decoupling of superfluid and normal
+oscillation modes first suggested in [Gusakov & Kantor PRD 83, 081304(R)
+(2011)]. All calculations are made self-consistently within the finite
+temperature superfluid hydrodynamics. The general analytic formulas are derived
+for damping times due to the shear and bulk viscosities. These formulas
+describe both normal and superfluid neutron stars and are valid for oscillation
+modes of arbitrary multipolarity. We show that: (i) use of the ordinary
+one-fluid hydrodynamics is a good approximation, for most of the stellar
+temperatures, if one is interested in calculation of the damping times of
+normal f-modes; (ii) for radial and p-modes such an approximation is poor;
+(iii) the temperature dependence of damping times undergoes a set of rapid
+changes associated with resonance coupling of neighboring oscillation modes.
+The latter effect can substantially accelerate viscous damping of normal modes
+in certain stages of neutron-star thermal evolution.",1211.2452v1
+2013-03-07,Universal damping behavior of dipole oscillations of one-dimensional ultracold gases induced by quantum phase slips,"We study superflow decay via quantum phase slips in trapped one-dimensional
+(1D) quantum gases through dipole oscillations induced by sudden displacement
+of the trapping potential. We find the relation between the damping rate of the
+dipole oscillation $G$ and the phase-slip nucleation rate $\Gamma$ as $G\propto
+\Gamma/v$, where $v$ is the flow velocity. This relation allows us to show that
+damping of 1D Bose gases in optical lattices, which has been extensively
+studied in experiment, is due to quantum phase slips. It is also found that the
+damping rate versus the flow velocity obeys the scaling formula for an impurity
+potential even in the absence of an explicit impurity. We suggest that the
+damping rate at a finite temperature exhibits a universal crossover behavior
+upon changing the flow velocity.",1303.1616v1
+2013-07-16,Blow-up of solutions to the one-dimensional semilinear wave equation with damping depending on time and space variables,"In this paper, we give a small data blow-up result for the one-dimensional
+semilinear wave equation with damping depending on time and space variables. We
+show that if the damping term can be regarded as perturbation, that is,
+non-effective damping in a certain sense, then the solution blows up in finite
+time for any power of nonlinearity. This gives an affirmative answer for the
+conjecture that the critical exponent agrees with that of the wave equation
+when the damping is non-effective in one space dimension.",1307.4260v2
+2013-11-12,Landau damping: paraproducts and Gevrey regularity,"We give a new, simpler, proof of nonlinear Landau damping on T^d in
+Gevrey-1/s regularity (s > 1/3) which matches the regularity requirement
+predicted by the formal analysis of Mouhot and Villani in the original proof of
+Landau damping [Acta Mathematica 2011]. Our proof combines in a novel way ideas
+from the original proof of Landau damping and the proof of inviscid damping in
+2D Euler [arXiv:1306.5028]. As in the work on 2D Euler, we use paraproduct
+decompositions and controlled regularity loss to replace the Newton iteration
+scheme employed in the original proof. We perform time-response estimates
+adapted from the original proof to control the plasma echoes and couple them to
+energy estimates on the distribution function in the style of the work on 2D
+Euler.",1311.2870v1
+2014-02-26,Comparison of methods for numerical calculation of continuum damping,"Continuum resonance damping is an important factor in determining the
+stability of certain global modes in fusion plasmas. A number of analytic and
+numerical approaches have been developed to compute this damping, particularly
+in the case of the toroidicity-induced shear Alfv\'en eigenmode. This paper
+compares results obtained using an analytical perturbative approach with those
+found using resistive and complex contour numerical approaches. It is found
+that the perturbative method does not provide accurate agreement with reliable
+numerical methods for the range of parameters examined. This discrepancy exists
+even in the limit where damping approaches zero. When the perturbative
+technique is implemented using a standard finite element method, the damping
+estimate fails to converge with radial grid resolution. The finite elements
+used cannot accurately represent the eigenmode in the region of the continuum
+resonance, regardless of the number of radial grid points used.",1402.6389v1
+2014-05-16,Quantum corrections to nonlinear ion acoustic wave with Landau damping,"Quantum corrections to nonlinear ion acoustic wave with Landau damping have
+been computed using Wigner equation approach. The dynamical equation governing
+the time development of nonlinear ion acoustic wave with semiclassical quantum
+corrections is shown to have the form of higher KdV equation which has higher
+order nonlinear terms coming from quantum corrections, with the usual classical
+and quantum corrected Landau damping integral terms.
+  The conservation of total number of ions is shown from the evolution
+equation. The decay rate of KdV solitary wave amplitude due to presence of
+Landau damping terms has been calculated assuming the Landau damping parameter
+$\alpha_1 = \sqrt{{m_e}/{m_i}}$ to be of the same order of the quantum
+parameter $Q = {\hbar^2}/({24 m^2 c^2_{s} L^2})$. The amplitude is shown to
+decay very slowly with time as determined by the quantum factor $ Q$.",1405.4107v1
+2014-05-19,Mesh Size and Damped Edge Effects in Micromagnetic Spin Wave Simulation,"We have studied the dependence of spin wave dispersion on the characteristics
+of the mesh used in a finite element micromagnetic simulation. It is shown that
+the dispersion curve has a cut off at a frequency which is analytically
+predictable. The frequency depends on the average mesh length used for the
+simulation. Based on this, a recipe to effectively obtain the dispersion
+relation has been suggested. In a separate study, spin wave reflections are
+absorbed by introducing highly damped edges in the device. However, an abrupt
+change in the damping parameter causes reflections. We compare damping profiles
+and identify an exponential damping profile as causing significantly less
+reflections.",1405.4615v2
+2014-07-08,Fourier-Hermite spectral representation for the Vlasov-Poisson system in the weakly collisional limit,"We study Landau damping in the 1+1D Vlasov-Poisson system using a
+Fourier-Hermite spectral representation. We describe the propagation of free
+energy in phase space using forwards and backwards propagating Hermite modes
+recently developed for gyrokinetics [Schekochihin et al. (2014)]. The change in
+the electric field corresponds to the net Hermite flux via a free energy
+evolution equation. In linear Landau damping, decay in the electric field
+corresponds to forward propagating Hermite modes; in nonlinear damping, the
+initial decay is followed by a growth phase characterised by the generation of
+backwards propagating Hermite modes by the nonlinear term. The free energy
+content of the backwards propagating modes increases exponentially until
+balancing that of the forward propagating modes. Thereafter there is no
+systematic net Hermite flux, so the electric field cannot decay and the
+nonlinearity effectively suppresses Landau damping. These simulations are
+performed using the fully-spectral 5D gyrokinetics code SpectroGK [Parker et
+al. 2014], modified to solve the 1+1D Vlasov-Poisson system. This captures
+Landau damping via an iterated L\'enard-Bernstein collision operator or via
+Hou-Li filtering in velocity space. Therefore the code is applicable even in
+regimes where phase-mixing and filamentation are dominant.",1407.1932v1
+2014-08-14,Particle Dynamics in Damped Nonlinear Quadrupole Ion Traps,"We examine the motions of particles in quadrupole ion traps as a function of
+damping and trapping forces, including cases where nonlinear damping or
+nonlinearities in the electric field geometry play significant roles. In the
+absence of nonlinearities, particles are either damped to the trap center or
+ejected, while their addition brings about a rich spectrum of stable closed
+particle trajectories. In three-dimensional (3D) quadrupole traps, the extended
+orbits are typically confined to the trap axis, and for this case we present a
+1D analysis of the relevant equation of motion. We follow this with an analysis
+of 2D quadrupole traps that frequently show diamond-shaped closed orbits. For
+both the 1D and 2D cases we present experimental observations of the calculated
+trajectories in microparticle ion traps. We also report the discovery of a new
+collective behavior in damped 2D microparticle ion traps, where particles
+spontaneously assemble into a remarkable knot of overlapping, corotating
+diamond orbits, self-stabilized by air currents arising from the particle
+motion.",1409.6262v1
+2015-01-03,Finite-Parameters Feedback Control for Stabilizing Damped Nonlinear Wave Equations,"In this paper we introduce a finite-parameters feedback control algorithm for
+stabilizing solutions of various classes of damped nonlinear wave equations.
+Specifically, stabilization the zero steady state solution of initial boundary
+value problems for nonlinear weakly and strongly damped wave equations,
+nonlinear wave equation with nonlinear damping term and some related nonlinear
+wave equations, introducing a feedback control terms that employ parameters,
+such as, finitely many Fourier modes, finitely many volume elements and
+finitely many nodal observables and controllers. In addition, we also establish
+the stabilization of the zero steady state solution to initial boundary value
+problem for the damped nonlinear wave equation with a controller acting in a
+proper subdomain. Notably, the feedback controllers proposed here can be
+equally applied for stabilizing other solutions of the underlying equations.",1501.00556v1
+2015-06-26,A Universal Damping Mechanism of Quantum Vibrations in Deep Sub-Barrier Fusion Reactions,"We demonstrate the damping of quantum octupole vibrations near the touching
+point when two colliding nuclei approach each other in the mass-asymmetric
+$^{208}$Pb + $^{16}$O system, for which the strong fusion hindrance was clearly
+observed. We, for the first time, apply the random-phase approximation method
+to the heavy-mass asymmetric di-nuclear system to calculate the transition
+strength $B$(E3) as a function of the center-of-mass distance. The obtained
+$B$(E3) strengths are substantially damped near the touching point, because the
+single-particle wave functions of the two nuclei strongly mix with each other
+and a neck is formed. The energy-weighted sums of $B$(E3) are also strongly
+correlated with the damping factor which is phenomenologically introduced in
+the standard coupled-channel calculations to reproduce the fusion hindrance.
+This strongly indicates that the damping of the quantum vibrations universally
+occurs in the deep sub-barrier fusion reactions.",1506.07963v1
+2015-07-28,Phenomenology of chiral damping in noncentrosymmetric magnets,"A phenomenology of magnetic chiral damping is proposed in the context of
+magnetic materials lacking inversion symmetry breaking. We show that the
+magnetic damping tensor adopts a general form that accounts for a component
+linear in magnetization gradient in the form of Lifshitz invariants. We propose
+different microscopic mechanisms that can produce such a damping in
+ferromagnetic metals, among which spin pumping in the presence of anomalous
+Hall effect and an effective ""$s$-$d$"" Dzyaloshinskii-Moriya antisymmetric
+exchange. The implication of this chiral damping in terms of domain wall motion
+is investigated in the flow and creep regimes. These predictions have major
+importance in the context of field- and current-driven texture motion in
+noncentrosymmetric (ferro-, ferri-, antiferro-)magnets, not limited to metals.",1507.07762v1
+2015-08-06,"Phenomenological description of the nonlocal magnetization relaxation in magnonics, spintronics, and domain-wall dynamics","A phenomenological equation called Landau-Lifshitz-Baryakhtar (LLBar)
+equation, which could be viewed as the combination of Landau-Lifshitz (LL)
+equation and an extra ""exchange damping"" term, was derived by Baryakhtar using
+Onsager's relations. We interpret the origin of this ""exchange damping"" as
+nonlocal damping by linking it to the spin current pumping. The LLBar equation
+is investigated numerically and analytically for the spin wave decay and domain
+wall motion. Our results show that the lifetime and propagation length of
+short-wavelength magnons in the presence of nonlocal damping could be much
+smaller than those given by LL equation. Furthermore, we find that both the
+domain wall mobility and the Walker breakdown field are strongly influenced by
+the nonlocal damping.",1508.01478v1
+2016-01-05,Vlasov Simulations of Electron-Ion Collision Effects on Damping of Electron Plasma Waves,"Collisional effects can play an essential role in the dynamics of plasma
+waves by setting a minimum damping rate and by interfering with wave-particle
+resonances. Kinetic simulations of the effects of electron-ion pitch angle
+scattering on Electron Plasma Waves (EPWs) are presented here. In particular,
+the effects of such collisions on the frequency and damping of small-amplitude
+EPWs for a range of collision rates and wave phase velocities are computed and
+compared with theory. Both the Vlasov simulations and linear kinetic theory
+find the direct contribution of electron-ion collisions to wave damping is
+about a factor of two smaller than is obtained from linearized fluid theory. To
+our knowledge, this simple result has not been published before.
+  Simulations have been carried out using a grid-based (Vlasov) approach, based
+on a high-order conservative finite difference method for discretizing the
+Fokker-Planck equation describing the evolution of the electron distribution
+function. Details of the implementation of the collision operator within this
+framework are presented. Such a grid-based approach, which is not subject to
+numerical noise, is of particular interest for the accurate measurements of the
+wave damping rates.",1601.01002v1
+2016-02-13,The effect of orbital damping during planet migration on the Inclination and Eccentricity Distributions of Neptune Trojans,"We explore planetary migration scenarios for formation of high inclination
+Neptune Trojans (NTs) and how they are affected by the planetary migration of
+Neptune and Uranus. If Neptune and Uranus's eccentricity and inclination were
+damped during planetary migration, then their eccentricities and inclinations
+were higher prior and during migration than their current values. Using test
+particle integrations we study the stability of primordial NTs, objects that
+were initially Trojans with Neptune prior to migration. We also study
+Trans-Neptunian objects captured into resonance with Neptune and becoming NTs
+during planet migration. We find that most primordial NTs were unstable and
+lost if eccentricity and inclination damping took place during planetary
+migration. With damping, secular resonances with Neptune can increase a low
+eccentricity and inclination population of Trans-Neptunian objects increasing
+the probability that they are captured into 1:1 resonance with Neptune,
+becoming high inclination NTs. We suggest that the resonant trapping scenario
+is a promising and more effective mechanism explaining the origin of NTs that
+is particularly effective if Uranus and Neptune experienced eccentricity and
+inclination damping during planetary migration.",1602.04303v1
+2016-03-08,Damping of the Higgs and Nambu-Goldstone modes of superfluid Bose gases at finite temperatures,"We study collective modes of superfluid Bose gases in optical lattices at
+commensurate fillings. We focus on the vicinity of the quantum phase transition
+to the Mott insulator, where there exists the Higgs amplitude mode in addition
+to the Nambu-Goldstone phase mode associated with the spontaneous U(1) symmetry
+breaking. We analyze finite-temperature effects on the damping of the
+collective modes by using an effective spin-1 model and the field theoretical
+methods based on the finite-temperature Green's function. We calculate the
+damping rates up to 1-loop order and evaluate them analytically and
+numerically. We show that the damping rate of the Higgs mode increases with
+increasing the temperature but it remains underdamped up to a typical
+temperature achieved in experiments. Moreover, we find that the Nambu-Goldstone
+mode attenuates via a Landau damping process resulting from interactions with
+the Higgs mode and it can be overdamped at the typical temperature in a certain
+parameter region.",1603.02395v1
+2016-04-12,Offline software for the DAMPE experiment,"A software system has been developed for the DArk Matter Particle Explorer
+(DAMPE) mission, a satellite-based experiment. The DAMPE software is mainly
+written in C++ and steered using Python script. This article presents an
+overview of the DAMPE offline software, including the major architecture design
+and specific implementation for simulation, calibration and reconstruction. The
+whole system has been successfully applied to DAMPE data analysis, based on
+which some results from simulation and beam test experiments are obtained and
+presented.",1604.03219v6
+2016-04-18,Stabilization of Damped Waves on Spheres and Zoll Surfaces of Revolution,"We study the strong stabilization of wave equations on some sphere-like
+manifolds, with rough damping terms which do not satisfy the geometric control
+condition posed by Rauch-Taylor and Bardos-Lebeau-Rauch. We begin with an
+unpublished result of G. Lebeau, which states that on S^d , the indicator
+function of the upper hemisphere strongly stabilizes the damped wave equation,
+even though the equators, which are geodesics contained in the boundary of the
+upper hemisphere, do not enter the damping region. Then we extend this result
+on dimension 2, to Zoll surfaces of revolution, whose geometry is similar to
+that of S^2 . In particular, geometric objects such as the equator, and the
+hemi-surfaces are well defined. Our result states that the indicator function
+of the upper hemi-surface strongly stabilizes the damped wave equation, even
+though the equator, as a geodesic, does not enter the upper hemi-surface
+either.",1604.05218v2
+2016-07-25,Damping of parametrically excited magnons in the presence of the longitudinal spin Seebeck effect,"The impact of the longitudinal spin Seebeck effect (LSSE) on the magnon
+damping in magnetic-insulator/nonmagnetic-metal bilayers was recently discussed
+in several reports. However, results of those experiments can be blurred by
+multimode excitation within the measured linewidth. In order to avoid possible
+intermodal interference, we investigated the damping of a single magnon group
+in a platinum covered Yttrium Iron Garnet (YIG) film by measurement of the
+threshold of its parametric excitation. Both dipolar and exchange spin-wave
+branches were probed. It turned out that the LSSE-related modification of
+spin-wave damping in a micrometer-thick YIG film is too weak to be observed in
+the entire range of experimentally accessible wavevectors. At the same time,
+the change in the mean temperature of the YIG layer, which can appear by
+applying a temperature gradient, strongly modifies the damping value.",1607.07274v1
+2016-07-27,Frequency dispersion of small-amplitude capillary waves in viscous fluids,"This work presents a detailed study of the dispersion of capillary waves with
+small amplitude in viscous fluids using an analytically derived solution to the
+initial value problem of a small-amplitude capillary wave as well as direct
+numerical simulation. A rational parametrization for the dispersion of
+capillary waves in the underdamped regime is proposed, including predictions
+for the wavenumber of critical damping based on a harmonic oscillator model.
+The scaling resulting from this parametrization leads to a self-similar
+solution of the frequency dispersion of capillary waves that covers the entire
+underdamped regime, which allows an accurate evaluation of the frequency at a
+given wavenumber, irrespective of the fluid properties. This similarity also
+reveals characteristic features of capillary waves, for instance that critical
+damping occurs when the characteristic timescales of dispersive and dissipative
+mechanisms are balanced. In addition, the presented results suggest that the
+widely adopted hydrodynamic theory for damped capillary waves does not
+accurately predict the dispersion when viscous damping is significant and a new
+definition of the damping rate, which provides consistent accuracy in the
+underdamped regime, is presented.",1607.08266v1
+2016-10-18,On the stability of the Bresse system with frictional damping,"In this paper, we consider the Bresse system with frictional damping terms
+and prove some optimal decay results for the $L^2$-norm of the solution and its
+higher order derivatives. In fact, if we consider just one damping term acting
+on the second equation of the solution, we show that the solution does not
+decay at all. On the other hand, by considering one damping term alone acting
+on the third equation, we show that this damping term is strong enough to
+stabilize the whole system. In this case, we found a completely new stability
+number that depends on the parameters in the system.
+  In addition, we prove the optimality of the results by using eigenvalues
+expansions. Our obtained results have been proved under some assumptions on the
+wave speeds of the three equations in the Bresse system.",1610.05500v2
+2017-01-12,Blow-up for semilinear wave equations with the scale invariant damping and super-Fujita exponent,"The blow-up for semilinear wave equations with the scale invariant damping
+has been well-studied for sub-Fujita exponent. However, for super-Fujita
+exponent, there is only one blow-up result which is obtained in 2014 by
+Wakasugi in the case of non-effective damping. In this paper we extend his
+result in two aspects by showing that: (I) the blow-up will happen for bigger
+exponent, which is closely related to the Strauss exponent, the critical number
+for non-damped semilinear wave equations; (II) such a blow-up result is
+established for a wider range of the constant than the known non-effective one
+in the damping term.",1701.03232v3
+2017-02-17,Transition of multi-diffusive states in a biased periodic potential,"We study a frequency-dependent damping model of hyper-diffusion within the
+generalized Langevin equation. The model allows for the colored noise defined
+by its spectral density, assumed to be proportional to $\omega^{\delta-1}$ at
+low frequencies with $0<\delta<1$ (sub-Ohmic damping) or $1<\delta<2$
+(super-Ohmic damping), where the frequency-dependent damping is deduced from
+the noise by means of the fluctuation-dissipation theorem. It is shown that for
+super-Ohmic damping and certain parameters, the diffusive process of the
+particle in a titled periodic potential undergos sequentially four
+time-regimes: thermalization, hyper-diffusion, collapse and asymptotical
+restoration. For analysing transition phenomenon of multi-diffusive states, we
+demonstrate that the first exist time of the particle escaping from the locked
+state into the running state abides by an exponential distribution. The concept
+of equivalent velocity trap is introduced in the present model, moreover,
+reformation of ballistic diffusive system is also considered as a marginal
+situation, however there does not exhibit the collapsed state of diffusion.",1702.05370v1
+2017-09-27,Wave turbulence in vibrating plates : the effect of damping,"The effect of damping in the wave turbulence regime for thin vibrating plates
+is studied. An experimental method, allowing measurements of dissipation in the
+system at all scales, is first introduced. Practical experimental devices for
+increasing the dissipation are used. The main observable consequence of
+increasing the damping is a significant modification in the slope of the power
+spectral density, so that the observed power laws are not in a pure inertial
+regime. However, the system still displays a turbulent behavior with a cut-off
+frequency that is determined by the injected power which does not depend on
+damping. By using the measured damping power-law in numerical simulations,
+similar conclusions are drawn out.",1709.09438v1
+2017-11-02,Vibration Damping of Carbon Nanotube Assembly Materials,"Vibration reduction is of great importance in various engineering
+applications, and a material that exhibits good vibration damping along with
+high strength and modulus has become more and more vital. Owing to the superior
+mechanical property of carbon nanotube (CNT), new types of vibration damping
+material can be developed. This paper presents recent advancements, including
+our progresses, in the development of high-damping macroscopic CNT assembly
+materials, such as forests, gels, films, and fibers. In these assemblies,
+structural deformation of CNTs, zipping and unzipping at CNT connection nodes,
+strengthening and welding of the nodes, and sliding between CNTs or CNT bundles
+are playing important roles in determining the viscoelasticity, and elasticity
+as well. Towards the damping enhancement, strategies for micro-structure and
+interface design are also discussed.",1711.00623v1
+2017-12-05,Dark Matter Annihilation from Nearby Ultra-compact Micro Halos to Explain the Tentative Excess at ~1.4 TeV in DAMPE data,"The tentative 1.4 TeV excess in the $e^+e^-$ spectrum measured by The DArk
+Matter Particle Explorer (DAMPE) motivates the possible existence of one or
+more local dark matter concentrated regions. In particular, Ultra-compact Micro
+Halos (UCMHs) seeded by large density perturbations in the early universe,
+allocated within ~0.3 kpc from the solar system, could provide the potential
+source of electrons and positrons produced from dark matter annihilation,
+enough to explain the DAMPE signal. Here we consider a UCMH with density
+profile assuming radial in-fall and explore the preferred halo parameters to
+explain the 1.4 TeV ""DAMPE excess"". We find that typical parameter space of
+UCMHs can easily explain the ""DAMPE excess"" with usual thermal-averaged
+annihilation cross section of WIMP. The fraction of dark matter stored in such
+UCMHs in the Galactic-scale halo can be reduced to as small as $O(10^{-5})$,
+well within the current cosmological and astrophysical constraints.",1712.01724v2
+2017-12-21,A new charge reconstruction algorithm for the DAMPE silicon microstrip detector,"The DArk Matter Particle Explorer (DAMPE) is one of the four satellites
+within the Strategic Pioneer Research Program in Space Science of the Chinese
+Academy of Science (CAS). The Silicon-Tungsten Tracker (STK), which is composed
+of 768 singled-sided silicon microstrip detectors, is one of the four
+subdetectors in DAMPE, providing track reconstruction and charge identification
+for relativistic charged particles. The charge response of DAMPE silicon
+microstrip detectors is complicated, depending on the incident angle and impact
+position. A new charge reconstruction algorithm for the DAMPE silicon
+microstrip detector is introduced in this paper. This algorithm can correct the
+complicated charge response, and was proved applicable by the ion test beam.",1712.08011v1
+2018-01-23,The dominancy of damping like torque for the current induced magnetization switching in Pt/Co/W multilayers,"Two classes of spin-orbit coupling (SOC) mechanisms have been considered as
+candidate sources for the spin orbit torque (SOT): the spin Hall Effect (SHE)
+in heavy metals with strong SOC and the Rashba effect arising from broken
+inversion symmetry at material surfaces and interfaces. In this work, we have
+investigated the SOT in perpendicularly magnetized Pt/Co/W films, which is
+compared with the results in Pt/Co/AlOx films. Theoretically, in the case of
+the asymmetric structure of trilayers with opposite sign of spin Hall angle,
+both damping like torque and field like torque due to the SHE and the Rashba
+effect will be enhanced. Using the harmonic measurements, we have characterized
+the effective fields corresponding to the damping like torque and the field
+like torque, but we have found the dominancy of damping like torque in the
+Pt/Co/W films. It is much different from the results in the Pt/Co/AlOx films,
+in which both the damping like torque and the field like torque are strong.",1801.07408v1
+2018-02-20,The damped wave equation with unbounded damping,"We analyze new phenomena arising in linear damped wave equations on unbounded
+domains when the damping is allowed to become unbounded at infinity. We prove
+the generation of a contraction semigroup, study the relation between the
+spectra of the semigroup generator and the associated quadratic operator
+function, the convergence of non-real eigenvalues in the asymptotic regime of
+diverging damping on a subdomain, and we investigate the appearance of
+essential spectrum on the negative real axis. We further show that the presence
+of the latter prevents exponential estimates for the semigroup and turns out to
+be a robust effect that cannot be easily canceled by adding a positive
+potential. These analytic results are illustrated by examples.",1802.07026v1
+2018-05-29,Enhancing precision of damping rate by PT symmetric Hamiltonian,"We utilize quantum Fisher information to investigate the damping parameter
+precision of a dissipative qubit. PT symmetric non-Hermitian Hamiltonian is
+used to enhance the parameter precision in two models: one is direct PT
+symmetric quantum feedback; the other is that the damping rate is encoded into
+a effective PT symmetric non-Hermitian Hamiltonian conditioned on the absence
+of decay events. We find that compared with the case without feedback and with
+Hermitian quantum feedback, direct PT symmetric non-Hermitan quantum feedback
+can obtain better precision of damping rate. And in the second model the result
+shows that the uncertainty of damping rate can be close to 0 at the exceptional
+point. We also obtain that non-maximal multiparticle entanglement can improve
+the precision to reach Heisenberg limit.",1805.11216v1
+2018-05-31,Damping Effect on PageRank Distribution,"This work extends the personalized PageRank model invented by Brin and Page
+to a family of PageRank models with various damping schemes. The goal with
+increased model variety is to capture or recognize a larger number of types of
+network activities, phenomena and propagation patterns. The response in
+PageRank distribution to variation in damping mechanism is then characterized
+analytically, and further estimated quantitatively on 6 large real-world link
+graphs. The study leads to new observation and empirical findings. It is found
+that the difference in the pattern of PageRank vector responding to parameter
+variation by each model among the 6 graphs is relatively smaller than the
+difference among 3 particular models used in the study on each of the graphs.
+This suggests the utility of model variety for differentiating network
+activities and propagation patterns. The quantitative analysis of the damping
+mechanisms over multiple damping models and parameters is facilitated by a
+highly efficient algorithm, which calculates all PageRank vectors at once via a
+commonly shared, spectrally invariant subspace. The spectral space is found to
+be of low dimension for each of the real-world graphs.",1806.00127v1
+2018-08-10,Relativistic charge solitons created due to nonlinear Landau damping: A candidate for explaining coherent radio emission in pulsars,"A potential resolution for the generation of coherent radio emission in
+pulsar plasma is the existence of relativistic charge solitons, which are
+solutions of nonlinear Schr\""{o}dinger equation (NLSE). In an earlier study,
+Melikidze et al. (2000) investigated the nature of these charge solitons;
+however, their analysis ignored the effect of nonlinear Landau damping, which
+is inherent in the derivation of the NLSE in the pulsar pair plasma. In this
+paper we include the effect of nonlinear Landau damping and obtain solutions of
+the NLSE by applying a suitable numerical scheme. We find that for reasonable
+parameters of the cubic nonlinearity and nonlinear Landau damping, soliton-like
+intense pulses emerge from an initial disordered state of Langmuir waves and
+subsequently propagate stably over sufficiently long times, during which they
+are capable of exciting the coherent curvature radiation in pulsars. We
+emphasize that this emergence of {\em stable} intense solitons from a
+disordered state does not occur in a purely cubic NLSE; thus, it is {\em
+caused} by the nonlinear Landau damping.",1808.03657v1
+2018-11-21,Super Damping of Mechanical Vibrations,"We report the phenomenon of coherent super decay, where a linear sum of
+several damped oscillators can collectively decay much faster than the
+individual ones in the first stage, followed by stagnating ones after more than
+90 percent of the energy has already been dissipated. The parameters of the
+damped oscillators for CSD are determined by the process of response function
+decomposition, which is to use several slow decay response functions to
+approximate the response function of a fast decay reference resonator. Evidence
+established in experiments and in finite element simulations not only strongly
+supported the numerical investigations, but also uncovered an unexplored region
+of the tuned mass damper parameter space where TMDs with total mass less than
+0.2 percent of a primary free body can damp its first resonance up to a damping
+ratio of 4.6 percent. Our findings also shed light onto the intriguing
+underline connections between complex functions with different singular points.",1811.08621v2
+2018-11-29,Flowing fibers as a proxy of turbulence statistics,"The flapping states of a flexible fiber fully coupled to a three-dimensional
+turbulent flow are investigated via state-of-the-art numerical methods. Two
+distinct flapping regimes are predicted by the phenomenological theory recently
+proposed by Rosti et al. [Phys. Rev. Lett. 121, 044501, 2018]: the under-damped
+regime, where the elasticity strongly affects the fiber dynamics, and the
+over-damped regime, where the elastic effects are strongly inhibited. In both
+cases we can identify a critical value of the bending rigidity of the fiber by
+a resonance condition, which further provides a distinction between different
+flapping behaviors, especially in the under-damped case. We validate the theory
+by means of direct numerical simulations and find that, both for the
+over-damped regime and for the under-damped one, fibers are effectively slaved
+to the turbulent fluctuations and can therefore be used as a proxy to measure
+various two-point statistics of turbulence. Finally, we show that this holds
+true also in the case of a passive fiber, without any feedback force on the
+fluid.",1811.12023v2
+2018-11-29,The Lugiato-Lefever equation with nonlinear damping caused by two photon absorption,"In this paper we investigate the effect of nonlinear damping on the
+Lugiato-Lefever equation $$ \i \partial_t a = -(\i-\zeta) a - da_{xx}
+-(1+\i\kappa)|a|^2a +\i f $$ on the torus or the real line. For the case of the
+torus it is shown that for small nonlinear damping $\kappa>0$ stationary
+spatially periodic solutions exist on branches that bifurcate from constant
+solutions whereas all nonconstant solutions disappear when the damping
+parameter $\kappa$ exceeds a critical value. These results apply both for
+normal ($d<0$) and anomalous ($d>0$) dispersion. For the case of the real line
+we show by the Implicit Function Theorem that for small nonlinear damping
+$\kappa>0$ and large detuning $\zeta\gg 1$ and large forcing $f\gg 1$ strongly
+localized, bright solitary stationary solutions exists in the case of anomalous
+dispersion $d>0$. These results are achieved by using techniques from
+bifurcation and continuation theory and by proving a convergence result for
+solutions of the time-dependent Lugiato-Lefever equation.",1811.12200v3
+2018-11-26,Linear Theory of Electron-Plasma Waves at Arbitrary Collisionality,"The dynamics of electron-plasma waves are described at arbitrary
+collisionality by considering the full Coulomb collision operator. The
+description is based on a Hermite-Laguerre decomposition of the velocity
+dependence of the electron distribution function. The damping rate, frequency,
+and eigenmode spectrum of electron-plasma waves are found as functions of the
+collision frequency and wavelength. A comparison is made between the
+collisionless Landau damping limit, the Lenard-Bernstein and Dougherty
+collision operators, and the electron-ion collision operator, finding large
+deviations in the damping rates and eigenmode spectra. A purely damped entropy
+mode, characteristic of a plasma where pitch-angle scattering effects are
+dominant with respect to collisionless effects, is shown to emerge numerically,
+and its dispersion relation is analytically derived. It is shown that such a
+mode is absent when simplified collision operators are used, and that
+like-particle collisions strongly influence the damping rate of the entropy
+mode.",1811.12855v2
+2019-01-17,"Influences of interfacial oxidization on surface magnetic energy, magnetic damping and spin-orbit-torques in Pt / ferromagnet / capping structures","We investigate the effect of capping layer (CAP) on the interfacial magnetic
+anisotropy energy density (K_S), magnetic damping ({\alpha}), and spin-orbit
+torques (SOTs) in heavy-metal (Pt) / ferromagnet (Co or Py) / CAP (MgO/Ta,
+HfOx, or TaN). At room temperature (RT) the CAP materials influence the
+effective magnitude of K_S, which is associated with a formation of interfacial
+magnetic oxides. The dynamical dissipation parameters of Co are considerably
+influenced by the CAP (especially MgO) while those of Py are not. This is
+possibly due to an extra magnetic damping via spin-pumping process across the
+Co/CoO interface and incoherent magnon generation (spin fluctuation) in the
+interfacial CoO. It is also observed that both anti-damping and field-like SOT
+efficiencies vary marginally with the CAP in the thickness ranges we examined.
+Our results reveal the crucial role of interfacial oxides on the perpendicular
+magnetic anisotropy, magnetic damping, and SOTs.",1901.05777v1
+2019-05-31,The amplitude of solar p-mode oscillations from three-dimensional convection simulations,"The amplitude of solar p-mode oscillations is governed by stochastic
+excitation and mode damping, both of which take place in the surface convection
+zone. However, the time-dependent, turbulent nature of convection makes it
+difficult to self-consistently study excitation and damping processes through
+the use of traditional one-dimensional hydrostatic models. To this end, we
+carried out \textit{ab initio} three-dimensional, hydrodynamical numerical
+simulations of the solar atmosphere to investigate how p-modes are driven and
+dissipated in the Sun. The description of surface convection in the simulations
+is free from the tuneable parameters typically adopted in traditional
+one-dimensional models. Mode excitation and damping rates are computed based on
+analytical expressions whose ingredients are evaluated directly from the
+three-dimensional model. With excitation and damping rates both available, we
+estimate the theoretical oscillation amplitude and frequency of maximum power,
+$\nu_{\max}$, for the Sun. We compare our numerical results with helioseismic
+observations, finding encouraging agreement between the two. The numerical
+method presented here provides a novel way to investigate the physical
+processes responsible for mode driving and damping, and should be valid for all
+solar-type oscillating stars.",1905.13397v2
+2019-10-03,Many-body collision contributions to electron momentum damping rates in a plasma influenced by electron strong coupling,"Experimental studies of electron-ion collision rates in an ultracold neutral
+plasma (UNP) can be conducted through measuring the rate of electron plasma
+oscillation damping. For sufficiently cold and dense conditions where strong
+coupling influences are important, the measured damping rate was faster by 37\%
+than theoretical expectations [W. Chen, C. Witte, and J. Roberts, Phys. Rev. E
+\textbf{96}, 013203 (2017)]. We have conducted a series of numerical
+simulations to isolate the primary source of this difference. By analyzing the
+distribution of electron velocity changes due to collisions in a molecular
+dynamics simulation, examining the trajectory of electrons with high deflection
+angle in such simulations, and examining the oscillation damping rate while
+varying the ratio of two-body to three-body electron-ion collision rates, we
+have found that the difference is consistent with the effect due to many-body
+collisions leading to bound electrons. This has implications for other
+electron-ion collision related transport properties in addition to electron
+oscillation damping.",1910.01707v1
+2019-10-18,Escape of a forced-damped particle from weakly nonlinear truncated potential well,"Escape from a potential well is an extreme example of transient behavior. We
+consider the escape of the harmonically forced particle under viscous damping
+from the benchmark truncated weakly nonlinear potential well. Main attention is
+paid to most interesting case of primary 1:1 resonance. The treatment is based
+on multiple-scales analysis and exploration of the slow-flow dynamics. Contrary
+to Hamiltonian case described in earlier works, in the case with damping the
+slow-flow equations are not integrable. However, if the damping is small
+enough, it is possible to analyze the perturbed slow-flow equations. The effect
+of the damping on the escape threshold is evaluated in the explicit analytic
+form. Somewhat unexpectedly, the escape mechanisms in terms of the slow flow
+are substantially different for the linear and weakly nonlinear cases.",1910.08545v1
+2020-02-07,Model of damping and anisotropy at elevated temperatures: application to granular FePt films,"Understanding the damping mechanism in finite size systems and its dependence
+on temperature is a critical step in the development of magnetic
+nanotechnologies. In this work, nano-sized materials are modeled via atomistic
+spin dynamics, the damping parameter being extracted from Ferromagnetic
+Resonance (FMR) simulations applied for FePt systems, generally used for
+heat-assisted magnetic recording media (HAMR). We find that the damping
+increases rapidly close to Tc and the effect is enhanced with decreasing system
+size, which is ascribed to scattering at the grain boundaries. Additionally,
+FMR methods provide the temperature dependence of both damping and the
+anisotropy, important for the development of HAMR. Semi-analytical calculations
+show that, in the presence of a grain size distribution, the FMR linewidth can
+decrease close to the Curie temperature due to a loss of inhomogeneous line
+broadening. Although FePt has been used in this study, the results presented in
+the current work are general and valid for any ferromagnetic material.",2002.02865v1
+2020-04-06,Damping-like Torque in Monolayer 1T-TaS$_2$,"A damping-like spin orbit torque (SOT) is a prerequisite for ultralow power
+spin logic devices. Here, we report on the damping-like SOT in just one
+monolayer of the conducting transition metal dichalcogenide (TMD) TaS$_2$
+interfaced with a NiFe (Py) ferromagnetic layer. The charge-spin conversion
+efficiency is found to be 0.25$\pm$0.03 and the spin Hall conductivity (2.63
+$\times$ 10$^5$ $\frac{\hbar}{2e}$ $\Omega^{-1}$ m$^{-1}$) is found to be
+superior to values reported for other TMDs. The origin of this large
+damping-like SOT can be found in the interfacial properties of the TaS$_2$/Py
+heterostructure, and the experimental findings are complemented by the results
+from density functional theory calculations. The dominance of damping-like
+torque demonstrated in our study provides a promising path for designing next
+generation conducting TMD based low-powered quantum memory devices.",2004.02649v1
+2020-05-15,Calibration and performance of the neutron detector onboard of the DAMPE mission,"The DArk Matter Particle Explorer (DAMPE), one of the four space-based
+scientific missions within the framework of the Strategic Pioneer Program on
+Space Science of the Chinese Academy of Sciences, has been successfully
+launched on Dec. 17th 2015 from Jiuquan launch center. One of the most
+important scientific goals of DAMPE is to search for the evidence of dark
+matter indirectly by measuring the spectrum of high energy cosmic-ray
+electrons. The neutron detector, one of the four sub-payloads of DAMPE, is
+designed to distinguish high energy electrons from hadron background by
+measuring the secondary neutrons produced in the shower. In this paper, a
+comprehensive introduction of the neutron detector is presented, including the
+design, the calibration and the performance. The analysis with simulated data
+and flight data indicates a powerful proton rejection capability of the neutron
+detector, which plays an essential role for TeV electron identification of
+DAMPE.",2005.07828v1
+2020-07-16,Linearized wave-damping structure of Vlasov-Poisson in $\mathbb R^3$,"In this paper we study the linearized Vlasov-Poisson equation for localized
+disturbances of an infinite, homogeneous Maxwellian background distribution in
+$\mathbb R^3_x \times \mathbb R^3_v$. In contrast with the confined case
+$\mathbb T^d _x \times \mathbb R_v ^d$, or the unconfined case $\mathbb R^d_x
+\times \mathbb R^d_v$ with screening, the dynamics of the disturbance are not
+scattering towards free transport as $t \to \pm \infty$: we show that the
+electric field decomposes into a very weakly-damped Klein-Gordon-type evolution
+for long waves and a Landau-damped evolution. The Klein-Gordon-type waves
+solve, to leading order, the compressible Euler-Poisson equations linearized
+about a constant density state, despite the fact that our model is
+collisionless, i.e. there is no trend to local or global thermalization of the
+distribution function in strong topologies. We prove dispersive estimates on
+the Klein-Gordon part of the dynamics. The Landau damping part of the electric
+field decays faster than free transport at low frequencies and damps as in the
+confined case at high frequencies; in fact, it decays at the same rate as in
+the screened case. As such, neither contribution to the electric field behaves
+as in the vacuum case.",2007.08580v1
+2020-07-25,Using a Lindbladian approach to model decoherence in two coupled nuclear spins via correlated phase-damping and amplitude damping noise channels,"In this work, we studied the relaxation dynamics of coherences of different
+order present in a system of two coupled nuclear spins. We used a previously
+designed model for intrinsic noise present in such systems which considers the
+Lindblad master equation for Markovian relaxation. We experimentally created
+zero-, single- and double- quantum coherences in several two-spin systems and
+performed a complete state tomography and computed state fidelity. We
+experimentally measured the decay of zero- and double- quantum coherences in
+these systems. The experimental data fitted well to a model that considers the
+main noise channels to be a correlated phase damping channel acting
+simultaneously on both spins in conjunction with a generalized amplitude
+damping channel acting independently on both spins. The differential relaxation
+of multiple-quantum coherences can be ascribed to the action of a correlated
+phase damping channel acting simultaneously on both the spins.",2007.12972v1
+2020-09-29,The effects of nonlinear damping on degenerate parametric amplification,"This paper considers the dynamic response of a single degree of freedom
+system with nonlinear stiffness and nonlinear damping that is subjected to both
+resonant direct excitation and resonant parametric excitation, with a general
+phase between the two. This generalizes and expands on previous studies of
+nonlinear effects on parametric amplification, notably by including the effects
+of nonlinear damping, which is commonly observed in a large variety of systems,
+including micro- and nano-scale resonators. Using the method of averaging, a
+thorough parameter study is carried out that describes the effects of the
+amplitudes and relative phase of the two forms of excitation. The effects of
+nonlinear damping on the parametric gain are first derived. The transitions
+among various topological forms of the frequency response curves, which can
+include isolae, dual peaks, and loops, are determined, and bifurcation analyses
+in parameter spaces of interest are carried out. In general, these results
+provide a complete picture of the system response and allow one to select drive
+conditions of interest that avoid bistability while providing maximum amplitude
+gain, maximum phase sensitivity, or a flat resonant peak, in systems with
+nonlinear damping.",2009.14284v2
+2020-11-10,Damped oscillators within the general theory of Casimir and van der Waals forces,"It is demonstrated that the general theory of Casimir and van der Waals
+forces describes the interaction-induced equilibrium thermodynamic potentials
+of the damped harmonic oscillator bilinearly coupled to the environment. An
+extended model for a damped oscillator is suggested along the lines of the
+general theory of Casimir and van der Waals forces, and the corresponding
+thermodynamic quantities obtained. While the original model involves a heat
+bath consisting of a large number of free oscillators having infinitesimal
+damping functions, the extended model allows any generally admissible frequency
+and temperature dependent dissipative susceptibilities of the heat bath
+constituents, influenced by the additional dissipative environmental channels
+that are not directly linked to the system oscillator. Consequently, the
+results obtained are applicable to the frequency and temperature dependent
+damping function of the system oscillator.",2011.04960v2
+2021-01-03,The effect of flow on resonant absorption of slow MHD waves in magnetic flux tubes,"In this paper, we study kink and sausage oscillations in the presence of
+longitudinal background flow. We study resonant absorption of the kink and
+sausage modes in the slow continuum under magnetic pore conditions in the
+presence of flow. we determine the dispersion relation then solve it
+numerically, and find the frequencies and damping rates of the slow kink and
+sausage surface modes. We also, obtain analytical solution for the damping rate
+of the slow surface mode in the long wavelength limit. We show that in the
+presence of plasma flow, resonance absorption can result in strong damping for
+forward waves and can be considered as an efficient mechanism to justify the
+extremely rapid damping of slow surface sausage waves observed in magnetic
+pores. Also, the plasma flow reduces the efficiency of resonance absorption to
+damp backward waves. Furthermore, for the pore conditions, the resonance
+instability is avoided in our model.",2101.02064v1
+2021-02-02,Analysis of Lower Hybrid Drift Waves in Kappa Distributions over Solar Atmosphere,"Kappa distributions and with loss cone features have been frequently observed
+with flares emissions with the signatures of Lower hybrid waves. We have
+analysed the plasma with Kappa distributions and with loss cone features for
+the drift wave instabilities in perpendicular propagation for Large flare and
+Normal flare and Coronal condition . While analysing the growth/damping rate,
+we understand that the growth of propagation of EM waves increases with kappa
+distribution index for all the three cases. In comparing the propagation large
+flare shows lesser growth in compared with the normal and the coronal plasmas.
+When added the loss cone features to Kappa distributions, we find that the
+damping of EM wave propagation takes place. The damping rate EM waves is
+increases with perpendicular temperature and loss cone index l, in all the
+three cases but damping is very high for large flare and then normal in
+comparision with coronal condition. This shows that the lower hybrid damping
+may be the source of coronal heating.",2102.01323v1
+2021-02-25,Regularity and stability of the semigroup associated with some interacting elastic systems I: A degenerate damping case,"In this paper, we examine regularity and stability issues for two damped
+abstract elastic systems. The damping involves the average velocity and a
+fractional power $\theta$, with $\theta$ in $[-1,1]$, of the principal
+operator. The matrix operator defining the damping mechanism for the coupled
+system is degenerate. First, we prove that for $\theta$ in $(1/2,1]$, the
+underlying semigroup is not analytic, but is differentiable for $\theta$ in
+$(0,1)$; this is in sharp contrast with known results for a single similarly
+damped elastic system, where the semigroup is analytic for $\theta$ in
+$[1/2,1]$; this shows that the degeneracy dominates the dynamics of the
+interacting systems, preventing analyticity in that range. Next, we show that
+for $\theta$ in $(0,1/2]$, the semigroup is of certain Gevrey classes. Finally,
+we show that the semigroup decays exponentially for $\theta$ in $[0,1]$, and
+polynomially for $\theta$ in $[-1,0)$. To prove our results, we use the
+frequency domain method, which relies on resolvent estimates. Optimality of our
+resolvent estimates is also established. Several examples of application are
+provided.",2102.13217v4
+2021-03-05,Existence and congruence of global attractors for damped and forced integrable and nonintegrable discrete nonlinear Schrödinger equations,"We study two damped and forced discrete nonlinear Schr\""odinger equations on
+the one-dimensional infinite lattice. Without damping and forcing they are
+represented by the integrable Ablowitz-Ladik equation (AL) featuring non-local
+cubic nonlinear terms, and its standard (nonintegrable) counterpart with local
+cubic nonlinear terms (DNLS). The global existence of a unique solution to the
+initial value problem for both, the damped and forced AL and DNLS, is proven.
+It is further shown that for sufficiently close initial data, their
+corresponding solutions stay close for all times. Concerning the asymptotic
+behaviour of the solutions to the damped and forced AL and DNLS, for the former
+a sufficient condition for the existence of a restricted global attractor is
+established while it is shown that the latter possesses a global attractor.
+Finally, we prove the congruence of the restricted global AL attractor and the
+DNLS attractor for dynamics ensuing from initial data contained in an
+appropriate bounded subset in a Banach space.",2103.03533v1
+2021-05-17,Dissipation of Oscillation Energy and Distribution of Damping Power in a Multimachine Power System: A Small-signal Analysis,"This paper revisits the concept of damping torque in a multimachine power
+system and its relation to the dissipation of oscillation energy in synchronous
+machine windings. As a multimachine extension of an existing result on a
+single-machine-infinite-bus (SMIB) system, we show that the total damping power
+for a mode stemming from the interaction of electromagnetic torques and rotor
+speeds is equal to the sum of average power dissipations in the generator
+windings corresponding to the modal oscillation. Further, counter-intuitive to
+the SMIB result, we demonstrate that, although the equality holds on an
+aggregate, such is not the case for individual machines in an interconnected
+system. To that end, distribution factors are derived for expressing the
+average damping power of each generator as a linear combination of average
+powers of modal energy dissipation in the windings of all machines in the
+system. These factors represent the distribution of damping power in a
+multimachine system. The results are validated on IEEE 4-machine and 16-machine
+test systems.",2105.07618v2
+2021-06-04,Imaging spin-wave damping underneath metals using electron spins in diamond,"Spin waves in magnetic insulators are low-damping signal carriers that could
+enable a new generation of spintronic devices. The excitation, control, and
+detection of spin waves by metal electrodes is crucial for interfacing these
+devices to electrical circuits. It is therefore important to understand
+metal-induced damping of spin-wave transport, but characterizing this process
+requires access to the underlying magnetic films. Here we show that spins in
+diamond enable imaging of spin waves that propagate underneath metals in
+magnetic insulators, and then use this capability to reveal a 100-fold increase
+in spin-wave damping. By analyzing spin-wave-induced currents in the metal, we
+derive an effective damping parameter that matches these observations well. We
+furthermore detect buried scattering centers, highlighting the technique's
+power for assessing spintronic device quality. Our results open new avenues for
+studying metal - spin-wave interaction and provide access to interfacial
+processes such as spin-wave injection via the spin-Hall effect.",2106.02508v2
+2021-06-04,Inherent Non-Linear Damping in Resonators with Inertia Amplification,"Inertia amplification is a mechanism coupling degrees of freedom within a
+vibrating structure. Its goal is to achieve an apparent high dynamic mass and,
+accordingly, a low resonance frequency. Such structures have been described for
+use in locally resonant metamaterials and phononic crystals to lower the
+starting frequency of a band gap without adding mass to the system. This study
+shows that any non-linear kinematic coupling between translational or
+rotational vibrations leads to the appearance of amplitude-dependent damping.
+The analytical derivation of the equation of motion of a resonator with inertia
+amplification creates insight in the damping process, and shows that the
+vibration damping increases with its amplitude. The theoretical study is
+validated by experimental evidence from two types of inertia-amplification
+resonators. Finally, the importance of amplitude-dependent damping is
+illustrated when the structure is used as a tuned mass damper for a cantilever
+beam.",2106.02576v2
+2021-06-30,On the effect of perturbations in first-order optimization methods with inertia and Hessian driven damping,"Second-order continuous-time dissipative dynamical systems with viscous and
+Hessian driven damping have inspired effective first-order algorithms for
+solving convex optimization problems. While preserving the fast convergence
+properties of the Nesterov-type acceleration, the Hessian driven damping makes
+it possible to significantly attenuate the oscillations. To study the stability
+of these algorithms with respect to perturbations, we analyze the behaviour of
+the corresponding continuous systems when the gradient computation is subject
+to exogenous additive errors. We provide a quantitative analysis of the
+asymptotic behaviour of two types of systems, those with implicit and explicit
+Hessian driven damping. We consider convex, strongly convex, and non-smooth
+objective functions defined on a real Hilbert space and show that, depending on
+the formulation, different integrability conditions on the perturbations are
+sufficient to maintain the convergence rates of the systems. We highlight the
+differences between the implicit and explicit Hessian damping, and in
+particular point out that the assumptions on the objective and perturbations
+needed in the implicit case are more stringent than in the explicit case.",2106.16159v2
+2021-07-13,A new approach to the quantization of the damped harmonic oscillator,"In this paper, a new approach for constructing Lagrangians for driven and
+undriven linearly damped systems is proposed, by introducing a redefined time
+coordinate and an associated coordinate transformation to ensure that the
+resulting Lagrangian satisfies the Helmholtz conditions. The approach is
+applied to canonically quantize the damped harmonic oscillator and although it
+predicts an energy spectrum that decays at the same rate to previous models,
+unlike those approaches it recovers the classical critical damping condition,
+which determines transitions between energy eigenstates, and is therefore
+consistent with the correspondence principle. It is also demonstrated how to
+apply the procedure to a driven damped harmonic oscillator.",2107.05827v3
+2021-11-21,Energy Transport in 1-Dimensional Oscillator Arrays With Hysteretic Damping,"Energy transport in 1-dimensional oscillator arrays has been extensively
+studied to date in the conservative case, as well as under weak viscous
+damping. When driven at one end by a sinusoidal force, such arrays are known to
+exhibit the phenomenon of supratransmission, i.e. a sudden energy surge above a
+critical driving amplitude. In this paper, we study 1-dimensional oscillator
+chains in the presence of hysteretic damping, and include nonlinear stiffness
+forces that are important for many materials at high energies. We first employ
+Reid's model of local hysteretic damping, and then study a new model of nearest
+neighbor dependent hysteretic damping to compare their supratransmission and
+wave packet spreading properties in a deterministic as well as stochastic
+setting. The results have important quantitative differences, which should be
+helpful when comparing the merits of the two models in specific engineering
+applications.",2111.10816v3
+2021-12-15,An Innovative Transverse Emittance Cooling Technique using a Laser-Plasma Wiggler,"We propose an innovative beam cooling scheme based on laser driven plasma
+wakefields to address the challenge of high luminosity generation for a future
+linear collider. For linear colliders, beam cooling is realised by means of
+damping rings equipped with wiggler magnets and accelerating cavities. This
+scheme ensures systematic reduction of phase space volume through synchrotron
+radiation emission whilst compensating for longitudinal momentum loss via an
+accelerating cavity. In this paper, the concept of a plasma wiggler and its
+effective model analogous to a magnetic wiggler are introduced; relation of
+plasma wiggler characteristics with damping properties are demonstrated;
+underpinning particle-in-cell simulations for laser propagation optimisation
+are presented. The oscillation of transverse wakefields and resulting
+sinusoidal probe beam trajectory are numerically demonstrated. The formation of
+an order of magnitude larger effective wiggler field compared to conventional
+wigglers is successfully illustrated. Potential damping ring designs on the
+basis of this novel plasma-based technology are presented and performance in
+terms of damping times and footprint was compared to an existing conventional
+damping ring design.",2112.08163v1
+2021-12-21,ISS-Based Robustness to Various Neglected Damping Mechanisms for the 1-D Wave PDE,"This paper is devoted to the study of the robustness properties of the 1-D
+wave equation for an elastic vibrating string under four different damping
+mechanisms that are usually neglected in the study of the wave equation: (i)
+friction with the surrounding medium of the string (or viscous damping), (ii)
+thermoelastic phenomena (or thermal damping), (iii) internal friction of the
+string (or Kelvin-Voigt damping), and (iv) friction at the free end of the
+string (the so-called passive damper). The passive damper is also the simplest
+boundary feedback law that guarantees exponential stability for the string. We
+study robustness with respect to distributed inputs and boundary disturbances
+in the context of Input-to-State Stability (ISS). By constructing appropriate
+ISS Lyapunov functionals, we prove the ISS property expressed in various
+spatial norms.",2112.11287v1
+2022-01-20,Derivation of the linear Boltzmann equation from the damped quantum Lorentz gas with a general scatterer configuration,"It is a fundamental problem in mathematical physics to derive macroscopic
+transport equations from microscopic models. In this paper we derive the linear
+Boltzmann equation in the low-density limit of a damped quantum Lorentz gas for
+a large class of deterministic and random scatterer configurations. Previously
+this result was known only for the single-scatterer problem on the flat torus,
+and for uniformly random scatterer configurations where no damping is required.
+The damping is critical in establishing convergence -- in the absence of
+damping the limiting behaviour depends on the exact configuration under
+consideration, and indeed, the linear Boltzmann equation is not expected to
+appear for periodic and other highly ordered configurations.",2201.08229v2
+2022-01-22,Effect of MagneticField on the Damping Behavior of a Ferrofluid based Damper,"This paper is an extension of our earlier work where we had reported a proof
+of concept for a ferrofluid based damper. The damper used ferrofluid as damping
+medium and it was seen that damping efficiency of the damper changes on
+application of magnetic field. The present paper deals with a systematic study
+of the effect of magnetic field on the damping efficiency of the damper.
+Results of these studies are reported. It is seen that damping ratio varies
+linearly with magnetic field ({\zeta} / H = 0.028 per kG) for magnetic field in
+range of 0.0 to 4.5 kG. It may be mentioned that ferrofluid is different from
+magnetorheological fluid even though both of them are magnetic field-responsive
+fluids. The ferrofluid-dampers are better suited than MR Fluid-dampers for
+their use in automobiles.",2201.09027v1
+2022-01-28,Machine learning-based method of calorimeter saturation correction for helium flux analysis with DAMPE experiment,"DAMPE is a space-borne experiment for the measurement of the cosmic-ray
+fluxes at energies up to around 100 TeV per nucleon. At energies above several
+tens of TeV, the electronics of DAMPE calorimeter would saturate, leaving
+certain bars with no energy recorded. In the present work we discuss the
+application of machine learning techniques for the treatment of DAMPE data, to
+compensate the calorimeter energy lost by saturation.",2201.12185v3
+2022-04-01,On the Importance of High-Frequency Damping in High-Order Conservative Finite-Difference Schemes for Viscous Fluxes,"This paper discusses the importance of high-frequency damping in high-order
+conservative finite-difference schemes for viscous terms in the Navier-Stokes
+equations. Investigating nonlinear instability encountered in a high-resolution
+viscous shock-tube simulation, we have discovered that a modification to the
+viscous scheme rather than the inviscid scheme resolves a problem with spurious
+oscillations around shocks. The modification introduces a term responsible for
+high-frequency damping that is missing in a conservative high-order viscous
+scheme. The importance of damping has been known for schemes designed for
+unstructured grids. However, it has not been recognized well in very high-order
+difference schemes, especially in conservative difference schemes. Here, we
+discuss how it is easily missed in a conservative scheme and how to improve
+such schemes by a suitably designed damping term.",2204.00393v1
+2022-06-20,Stability and Damping in the Disks of Massive Galaxies,"After their initial formation, disk galaxies are observed to be rotationally
+stable over periods of >6 Gyr, implying that any large velocity disturbances of
+stars and gas clouds are damped rapidly on the timescale of their rotation.
+However, it is also known that despite this damping, there must be a degree of
+random local motion to stabilize the orbits against degenerate collapse. A
+mechanism for such damping is proposed by a combination of inter-stellar
+gravitational interactions, and interactions with the Oort clouds and exo-Oort
+objects associated with each star. Analysis of the gravitational interactions
+between two stars is a three-body problem, because the stars are also in orbit
+round the large virtual mass of the galaxy. These mechanisms may produce rapid
+damping of large perturbations within a time period that is short on the scale
+of observational look-back time, but long on the scale of the disk rotational
+period for stars with small perturbations. This mechanism may also account for
+the locally observed mean perturbations in the Milky Way of 8-15~km/s for
+younger stars and 20-30~km/s for older stars.",2206.09671v2
+2022-09-15,Superfluid $^4$He as a rigorous test bench for different damping models in nanoelectromechanical resonators,"We have used nanoelectromechanical resonators to probe superfluid $^4$He at
+different temperature regimes, spanning over four orders of magnitude in
+damping. These regimes are characterized by the mechanisms which provide the
+dominant contributions to damping and the shift of the resonance frequency:
+tunneling two level systems at the lowest temperatures, ballistic phonons and
+rotons at few hundred mK, and laminar drag in the two-fluid regime below the
+superfluid transition temperature as well as in the normal fluid. Immersing the
+nanoelectromechanical resonators in fluid increases their effective mass
+substantially, decreasing their resonance frequency. Dissipationless superflow
+gives rise to a unique possibility to dramatically change the mechanical
+resonance frequency in situ, allowing rigorous tests on different damping
+models in mechanical resonators. We apply this method to characterize tunneling
+two-level system losses and magnetomotive damping in the devices.",2209.07229v2
+2022-11-08,On the injection scale of the turbulence in the partially ionized very local interstellar medium,"The cascade of magnetohydrodynamic (MHD) turbulence is subject to ion-neutral
+collisional damping and neutral viscous damping in the partially ionized
+interstellar medium. By examining the damping effects in the warm and partially
+ionized local interstellar medium, we find that the interstellar turbulence is
+damped by neutral viscosity at $\sim 261$ au and cannot account for the
+turbulent magnetic fluctuations detected by Voyager 1 and 2. The MHD turbulence
+measured by Voyager in the very local interstellar medium (VLISM) should be
+locally injected in the regime where ions are decoupled from neutrals for its
+cascade to survive the damping effects. With the imposed ion-neutral decoupling
+condition, and the strong turbulence condition for the observed Kolmogorov
+magnetic energy spectrum, we find that the turbulence in the VLISM is
+sub-Alfv\'{e}nic, and its largest possible injection scale is $\sim 194$ au.",2211.04496v1
+2022-12-11,"The overtone level spacing of a black hole quasinormal frequencies: a fingerprint of a local $SL(2,\mathbb{R})$ symmetry","The imaginary part of the quasinormal frequencies spectrum for a static and
+spherically symmetric black hole is analytically known to be equally spaced,
+both for the highly damped and the weakly damped families of quasinormal modes.
+Some interesting attempts have been made in the last twenty years to understand
+in simple ways this level spacing for the only case of highly damped
+quasinormal frequencies. Here, we show that the overtone level spacing, for
+both the highly damped and weakly damped families of quasinormal modes, can
+simply be understood as a fingerprint of a hidden local $SL(2,\mathbb{R})$
+symmetry, near different regions of the black hole spacetime, i.e. the
+near-horizon and the near-photon sphere regions.",2212.05538v1
+2022-12-15,Formation of shifted shock for the 3D compressible Euler equations with time-dependent damping,"In this paper, we show the shock formation to the compressible Euler
+equations with time-dependent damping $\frac{a\p u}{(1+t)^{\lam}}$ in three
+spatial dimensions without any symmetry conditions. It's well-known that for
+$\lam>1$, the damping is too weak to prevent the shock formation for suitably
+large data. However, the classical results only showed the finite existence of
+the solution. Follow the work by D.Christodoulou in\cite{christodoulou2007},
+starting from the initial isentropic and irrotational short pulse data, we show
+the formation of shock is characterized by the collapse of the characteristic
+hypersurfaces and the vanishing of the inverse foliation density function
+$\mu$, at which the first derivatives of the velocity and the density blow up,
+and the lifespan $T_{\ast}(a,\lam)$ is exponentially large. Moreover, the
+damping effect will shift the time of shock formation $T_{\ast}$. The methods
+in the paper can also be extended to the Euler equations with general
+time-decay damping.",2212.07828v1
+2023-01-15,Damped-driven system of bouncing droplets leading to deterministic diffusive behavior,"Damped-driven systems are ubiquitous in science, however the damping and
+driving mechanisms are often quite convoluted. This manuscript presents an
+experimental and theoretical investigation of a fluidic droplet on a vertically
+vibrating fluid bath as a damped-driven system. We study a fluidic droplet in
+an annular cavity with the fluid bath forced above the Faraday wave threshold.
+We model the droplet as a kinematic point particle in air and as inelastic
+collisions during impact with the bath. In both experiments and the model the
+droplet is observed to chaotically change velocity with a Gaussian
+distribution. Finally, the statistical distributions from experiments and
+theory are analyzed. Incredibly, this simple deterministic interaction of
+damping and driving of the droplet leads to more complex Brownian-like and
+Levy-like behavior.",2301.06041v2
+2023-03-01,Generation of intraparticle quantum correlations in amplitude damping channel and its robustness,"Quantum correlations between two or more different degrees of freedom of the
+same particle is sometimes referred to as intraparticle entanglement. In this
+work, we study these intra-particle correlations between two different degrees
+of freedom under various decoherence channels viz. amplitude damping,
+depolarising and phase damping channels. We observe a unique feature of the
+amplitude damping channel, wherein entanglement is shown to arise starting from
+separable states. In case of non maximally entangled input states, in addition
+to entanglement sudden death, the creation of entanglement is also observed,
+having an asymptotic decay over a long time. These counter-intuitive behaviours
+arise due to the subtle interplay of channel and input state parameters, and
+are not seen for interparticle entanglement without consideration of
+non-Markovian noise. It is also not observed for maximally entangled input
+states. Furthermore, investigation of entanglement evolution in phase damping
+and depolarizing channels shows its robustness against decoherence as compared
+to interparticle entanglement.",2303.01238v1
+2023-03-16,Quantum Brownian Motion in the Caldeira-Leggett Model with a Damped Environment,"We model a quantum system coupled to an environment of damped harmonic
+oscillators by following the approach of Caldeira-Leggett and adopting the
+Caldirola-Kanai Lagrangian for the bath oscillators. In deriving the master
+equation of the quantum system of interest (a particle in a general potential),
+we show that the potential is modified non-trivially by a new inverted harmonic
+oscillator term, induced by the damping of the bath oscillators. We analyze
+numerically the case of a particle in a double-well potential, and find that
+this modification changes both the rate of decoherence at short times and the
+well-transfer probability at longer times. We also identify a simple rescaling
+condition that keeps the potential fixed despite changes in the environmental
+damping. Here, the increase of environmental damping leads to a slowing of
+decoherence.",2303.09516v1
+2023-03-22,A Numerical Study of Landau Damping with PETSc-PIC,"We present a study of the standard plasma physics test, Landau damping, using
+the Particle-In-Cell (PIC) algorithm. The Landau damping phenomenon consists of
+the damping of small oscillations in plasmas without collisions. In the PIC
+method, a hybrid discretization is constructed with a grid of finitely
+supported basis functions to represent the electric, magnetic and/or
+gravitational fields, and a distribution of delta functions to represent the
+particle field. Approximations to the dispersion relation are found to be
+inadequate in accurately calculating values for the electric field frequency
+and damping rate when parameters of the physical system, such as the plasma
+frequency or thermal velocity, are varied. We present a full derivation and
+numerical solution for the dispersion relation, and verify the PETSC-PIC
+numerical solutions to the Vlasov-Poisson for a large range of wave numbers and
+charge densities.",2303.12620v1
+2023-04-07,Shifted shock formation for the 3D compressible Euler equations with damping and variation of the vorticity,"In this paper, we consider the shock formation problem for the
+3-dimensional(3D) compressible Euler equations with damping inspired by the
+work \cite{BSV3Dfulleuler}. It will be shown that for a class of large data,
+the damping can not prevent the formation of point shock, and the damping
+effect shifts the shock time and the wave amplitude while the shock location
+and the blow up direction remain the same with the information of this point
+shock being computed explicitly. Moreover, the vorticity is concentrated in the
+non-blow-up direction, which varies exponentially due to the damping effect.
+Our proof is based on the estimates for the modulated self-similar variables
+and lower bounds for the Lagrangian trajectories.",2304.03506v2
+2023-07-05,Bayesian evidence for two slow-wave damping models in hot coronal loops,"We compute the evidence in favour of two models, one based on field-aligned
+thermal conduction alone and another that includes thermal misbalance as well,
+in explaining the damping of slow magneto-acoustic waves in hot coronal loops.
+Our analysis is based on the computation of the marginal likelihood and the
+Bayes factor for the two damping models. We quantify their merit in explaining
+the apparent relationship between slow mode periods and damping times, measured
+with SOHO/SUMER in a set of hot coronal loops. The results indicate evidence in
+favour of the model with thermal misbalance in the majority of the sample, with
+a small population of loops for which thermal conduction alone is more
+plausible. The apparent possibility of two different regimes of slow-wave
+damping, if due to differences between the loops of host active regions and/or
+the photospheric dynamics, may help with revealing the coronal heating
+mechanism.",2307.02439v1
+2023-07-24,From characteristic functions to multivariate distribution functions and European option prices by the damped COS method,"We provide a unified framework for the computation of the distribution
+function and the computation of prices of financial options from the
+characteristic function of some density by the COS method. The classical COS
+method is numerically very efficient in one-dimension but cannot deal very well
+with certain financial options in general dimensions. Therefore, we introduce
+the damped COS method which can handle a large class of integrands very
+efficiently. We prove the convergence of the (damped) COS method and study its
+order of convergence. The (damped) COS method converges exponentially if the
+characteristic function decays exponentially. To apply the (damped) COS method,
+one has to specify two parameters: a truncation range for the multivariate
+density and the number of terms to approximate the truncated density by a
+cosine series. We provide an explicit formula for the truncation range and an
+implicit formula for the number of terms. Numerical experiments up to five
+dimensions confirm the theoretical results.",2307.12843v6
+2023-07-26,A Nonlinear Damped Metamaterial: Wideband Attenuation with Nonlinear Bandgap and Modal Dissipation,"In this paper, we incorporate the effect of nonlinear damping with the
+concept of locally resonant metamaterials to enable vibration attenuation
+beyond the conventional bandgap range. The proposed design combines a linear
+host cantilever beam and periodically distributed inertia amplifiers as
+nonlinear local resonators. The geometric nonlinearity induced by the inertia
+amplifiers causes an amplitude-dependent nonlinear damping effect. Through the
+implementation of both modal superposition and numerical harmonic methods the
+finite nonlinear metamaterial is accurately modelled. The resulting nonlinear
+frequency response reveals the bandgap is both amplitude-dependent and
+broadened. Furthermore, the modal frequencies are also attenuated due to the
+nonlinear damping effect. The theoretical results are validated experimentally.
+By embedding the nonlinear damping effect into locally resonant metamaterials,
+wideband attenuation of the proposed metamaterial is achieved, which opens new
+possibilities for versatile metamaterials beyond the limit of their linear
+counterparts.",2307.14165v2
+2023-09-22,Long time energy averages and a lower resolvent estimate for damped waves,"We consider the damped wave equation on a compact manifold. We propose
+different ways of measuring decay of the energy (time averages of lower energy
+levels, decay for frequency localized data...) and exhibit links with resolvent
+estimates on the imaginary axis. As an application we prove a universal
+logarithmic lower resolvent bound on the imaginary axis for the damped wave
+operator when the Geometric Control Condition (GCC) is not satisfied. This is
+to be compared to the uniform boundedness of the resolvent on that set when GCC
+holds. The proofs rely on (i) various (re-)formulations of the damped wave
+equation as a conservative hyperbolic part perturbed by a lower order damping
+term;(ii) a ""Plancherel-in-time"" argument as in classical proofs of the
+Gearhart-Huang-Pr{\""u}ss theorem; and (iii) an idea of Bony-Burq-Ramond of
+propagating a coherent state along an undamped trajectory up to Ehrenfest time.",2309.12709v1
+2023-12-12,Coordination of Damping Controllers: A Data-Informed Approach for Adaptability,"This work proposes a data-informed approach for an adaptable coordination of
+damping controllers. The novel concept of coordination is based on minimizing
+the Total Action, a single metric that measures the system's dynamic response
+post-disturbance. This is a performance measure based on the physics of the
+power system, which encapsulates the oscillation energy related to synchronous
+generators. Deep learning theory is used to propose a Total Action function
+approximator, which captures the relationship between the system wide-area
+measurements, the status of damping controllers, and the conditions of the
+disturbance. By commissioning the switching status (on/off) of damping
+controllers in real-time, the oscillation energy is reduced, enhancing the
+power system stability. The concept is tested in the Western North America
+Power System (wNAPS) and compared with a model-based approach for the
+coordination of damping controllers. The data-informed coordination outperforms
+the model-based approach, demonstrating exceptional adaptability and
+performance to handle multi-modal events. The proposed scheme shows outstanding
+reductions in low-frequency oscillations even under various operating
+conditions, fault locations, and time delay considerations.",2312.07739v1
+2024-01-26,Efficient Control of Magnetization Dynamics Via W/CuO$_\text{x}$ Interface,"Magnetization dynamics, which determine the speed of magnetization switching
+and spin information propagation, play a central role in modern spintronics.
+Gaining its control will satisfy the different needs of various spintronic
+devices. In this work, we demonstrate that the surface oxidized Cu
+(CuO$_\text{x}$) can be employed for the tunability of magnetization dynamics
+of ferromagnet (FM)/heavy metal (HM) bilayer system. The capping CuO$_\text{x}$
+layer in CoFeB/W/CuO$_\text{x}$ trilayer reduces the magnetic damping value in
+comparison with the CoFeB/W bilayer. The magnetic damping even becomes lower
+than that of the CoFeB/CuO$_\text{x}$ by ~ 16% inferring the stabilization of
+anti-damping phenomena. Further, the reduction in damping is accompanied by a
+very small reduction in the spin pumping-induced output DC voltage in the
+CoFeB/W/CuO$_\text{x}$ trilayer. The simultaneous observation of anti-damping
+and spin-to-charge conversion can be attributed to the orbital Rashba effect
+observed at the HM/CuO$_\text{x}$ interface. Our experimental findings
+illustrate that the cost-effective CuO$_\text{x}$ can be employed as an
+integral part of modern spintronics devices owing to its rich underneath
+spin-orbital physics.",2401.14708v1
+2024-02-08,The stability analysis based on viscous theory of Faraday waves in Hele-Shaw cells,"The linear instability of Faraday waves in Hele-Shaw cells is investigated
+with consideration of the viscosity of fluids after gap-averaging the governing
+equations due to the damping from two lateral walls and the dynamic behavior of
+contact angle. A new hydrodynamic model is thus derived and solved
+semi-analytically. The contribution of viscosity to critical acceleration
+amplitude is slight compared to other factors associated with dissipation, and
+the potential flow theory is sufficient to describe onset based on the present
+study, but the rotational component of velocity can change the timing of onset
+largely, which paradoxically comes from the viscosity. The model degenerates
+into a novel damped Mathieu equation if the viscosity is dropped with two
+damping terms referring to the gap-averaged damping and dissipation from
+dynamic contact angle, respectively. The former increases when the gap size
+decreases, and the latter grows as frequency rises. When it comes to the
+dispersion relation of Faraday waves, an unusual detuning emerges due to the
+imaginary part of the gap-averaged damping.",2402.05505v2
+2024-02-09,Damping of density oscillations from bulk viscosity in quark matter,"We study the damping of density oscillations in the quark matter phase that
+might occur in compact stars. To this end we compute the bulk viscosity and the
+associated damping time in three-flavor quark matter, considering both
+nonleptonic and semileptonic electroweak processes. We use two different
+equations of state of quark matter, more precisely, the MIT bag model and
+perturbative QCD, including the leading order corrections in the strong
+coupling constant. We analyze the dependence of our results on the density,
+temperature and value of strange quark mass in each case. We then find that the
+maximum of the bulk viscosity is in the range of temperature from 0.01 to 0.1
+MeV for frequencies around 1 kHz, while the associated minimal damping times of
+the density oscillations at those temperatures might be in the range of few to
+hundreds milliseconds. Our results suggest that bulk viscous damping might be
+relevant in the post-merger phase after the collision of two neutron stars if
+deconfined matter is achieved in the process.",2402.06595v1
+2013-09-02,Nonstrict inequality for Schmidt coefficients of three-qubit states,"Generalized Schmidt decomposition of pure three-qubit states has four
+positive and one complex coefficients. In contrast to the bipartite case, they
+are not arbitrary and the largest Schmidt coefficient restricts severely other
+coefficients. We derive a nonstrict inequality between three-qubit Schmidt
+coefficients, where the largest coefficient defines the least upper bound for
+the three nondiagonal coefficients or, equivalently, the three nondiagonal
+coefficients together define the greatest lower bound for the largest
+coefficient. In addition, we show the existence of another inequality which
+should establish an upper bound for the remaining Schmidt coefficient.",1309.0399v3
+2018-10-30,Generalized Stability of Heisenberg Coefficients,"Stembridge introduced the notion of stability for Kronecker triples which
+generalize Murnaghan's classical stability result for Kronecker coefficients.
+Sam and Snowden proved a conjecture of Stembridge concerning stable Kronecker
+triple, and they also showed an analogous result for Littlewood--Richardson
+coefficients. Heisenberg coefficients are Schur structure constants of the
+Heisenberg product which generalize both Littlewood--Richardson coefficients
+and Kronecker coefficients. We show that any stable triple for Kronecker
+coefficients or Littlewood--Richardson coefficients also stabilizes Heisenberg
+coefficients, and we classify the triples stabilizing Heisenberg coefficients.
+We also follow Vallejo's idea of using matrix additivity to generate Heisenberg
+stable triples.",1810.12512v1
+2003-08-05,Reliability of Calderbank-Shor-Steane Codes and Security of Quantum Key Distribution,"After Mayers (1996, 2001) gave a proof of the security of the
+Bennett-Brassard 1984 (BB84) quantum key distribution protocol, Shor and
+Preskill (2000) made a remarkable observation that a Calderbank-Shor-Steane
+(CSS) code had been implicitly used in the BB84 protocol, and suggested its
+security could be proven by bounding the fidelity, say F(n), of the
+incorporated CSS code of length n in the form 1-F(n) <= exp[-n E+o(n)] for some
+positive number E. This work presents such a number E=E(R) as a function of the
+rate of a code R, and a threshold R' such that E(R)>0 whenever R < R', which is
+larger than the achievable rate based on the Gilbert-Varshamov bound that is
+essentially due to Shor and Preskill (2000). The codes in the present work are
+robust against fluctuations of channel parameters, which fact is needed to
+establish the security rigorously and was not proved for rates above the
+Gilbert-Varshamov rate before in the literature. As a byproduct, the security
+of a modified BB84 protocol against any joint (coherent) attacks is proved
+quantitatively.",0308029v6
+2011-07-13,(In-)Stability of Singular Equivariant Solutions to the Landau-Lifshitz-Gilbert Equation,"In this paper we use formal asymptotic arguments to understand the stability
+proper- ties of equivariant solutions to the Landau-Lifshitz-Gilbert model for
+ferromagnets. We also analyze both the harmonic map heatflow and Schrodinger
+map flow limit cases. All asymptotic results are verified by detailed numerical
+experiments, as well as a robust topological argument. The key result of this
+paper is that blowup solutions to these problems are co-dimension one and hence
+both unstable and non-generic. Solutions permitted to deviate from radial
+symmetry remain global for all time but may, for suitable initial data,
+approach arbitrarily close to blowup. A careful asymptotic analysis of
+solutions near blowup shows that finite-time blowup corresponds to a saddle
+fixed point in a low dimensional dynamical system. Radial symmetry precludes
+motion anywhere but on the stable manifold towards blowup. A similar scenario
+emerges in the equivariant setting: blowup is unstable. To be more precise,
+blowup is co-dimension one both within the equivariant symmetry class and in
+the unrestricted class of initial data. The value of the parameter in the
+Landau-Lifshitz-Gilbert equation plays a very subdued role in the analysis of
+equivariant blowup, leading to identical blowup rates and spatial scales for
+all parameter values. One notable exception is the angle between solution in
+inner scale (which bubbles off) and outer scale (which remains), which does
+depend on parameter values. Analyzing near-blowup solutions, we find that in
+the inner scale these solution quickly rotate over an angle {\pi}. As a
+consequence, for the blowup solution it is natural to consider a continuation
+scenario after blowup where one immediately re-attaches a sphere (thus
+restoring the energy lost in blowup), yet rotated over an angle {\pi}. This
+continuation is natural since it leads to continuous dependence on initial
+data.",1107.2620v1
+1996-09-10,The Damping Tail of CMB Anisotropies,"By decomposing the damping tail of CMB anisotropies into a series of transfer
+functions representing individual physical effects, we provide ingredients that
+will aid in the reconstruction of the cosmological model from small-scale CMB
+anisotropy data. We accurately calibrate the model-independent effects of
+diffusion and reionization damping which provide potentially the most robust
+information on the background cosmology. Removing these effects, we uncover
+model-dependent processes such as the acoustic peak modulation and
+gravitational enhancement that can help distinguish between alternate models of
+structure formation and provide windows into the evolution of fluctuations at
+various stages in their growth.",9609079v1
+1997-09-16,Lyman-alpha emission as a tool to study high redshift damped systems,"We report a quantitative study of the escape of Lyman-alpha photons from an
+inhomogeneous optically thick medium that mimics the structure of damped
+Lyman-alpha absorbers. Modeling the optically thick disk with 3 components
+(massive stars and HII regions, dust, and neutral hydrogen), we study the
+resulting emission line profile that may arise near the extended damped
+absorption profile.",9709150v1
+1997-10-17,The chemical evolution of galaxies causing damped Ly$α$ absorption,"We have compiled all available data on chemical abundances in damped Lyman
+alpha absorption systems for comparison with results from our combined chemical
+and spectrophotometric galaxy evolution models. Preliminary results from
+chemically consistent calculations are in agreement with observations of damped
+Ly$\alpha$ systems.",9710193v1
+1998-01-26,Are Damped Lyman alpha Systems Rotating Disks ?,"We report on high spectral resolution observations of five damped Lyman alpha
+systems whose line velocity profiles and abundances are analyzed. By combining
+these data with information from the literature, we study the kinematics of the
+low and high ionization phases of damped systems and discuss the possibility
+that part of the motions is due to rotation.",9801243v1
+2001-10-29,Damping of inhomogeneities in neutralino dark matter,"The lightest supersymmetric particle, most likely the neutralino, might
+account for a large fraction of dark matter in the Universe. We show that the
+primordial spectrum of density fluctuations in neutralino cold dark matter
+(CDM) has a sharp cut-off due to two damping mechanisms: collisional damping
+during the kinetic decoupling of the neutralinos at O(10 MeV) and free
+streaming after last scattering of neutralinos. The cut-off in the primordial
+spectrum defines a minimal mass for CDM objects in hierarchical structure
+formation. For typical neutralino and sfermion masses the first gravitationally
+bound neutralino clouds have masses above 10^(-6) M_\odot.",0110601v1
+2002-08-03,Adiabatic Index of Dense Matter and Damping of Neutron Star Pulsations,"The adiabatic index Gamma_1 for perturbations of dense matter is studied
+under various physical conditions which can prevail in neutron star cores. The
+dependence of Gamma_1 on the composition of matter (in particular, on the
+presence of hyperons), on the stellar pulsation amplitude, and on the baryon
+superfluidity is analyzed. Timescales of damping of stellar pulsations are
+estimated at different compositions, temperatures, and pulsation amplitudes.
+Damping of pulsations by bulk viscosity in the neutron-star cores can prevent
+the stars to pulsate with relative amplitudes > (1-15)% (depending on the
+composition of matter).",0208078v1
+2003-01-07,Damping of Neutron Star Shear Modes by Superfluid Friction,"The forced motion of superfluid vortices in shear oscillations of rotating
+solid neutron star matter produces damping of the mode. A simple model of the
+unpinning and repinning processes is described, with numerical calculations of
+the consequent energy decay times. These are of the order of 1 s or more for
+typical anomalous X-ray pulsars but become very short for the general
+population of radio pulsars. The superfluid friction processes considered here
+may also be significant for the damping of r-modes in rapidly rotating neutron
+stars.",0301112v1
+2005-04-25,Radiative Effect on Particle Acceleration via Relativistic Electromagnetic Expansion,"The radiation damping effect on the diamagnetic relativistic pulse
+accelerator (DRPA) is studied in two-and-half dimensional Particle-in-Cell
+(PIC) simulation with magnetized electron-positron plasmas. Self-consistently
+solved radiation damping force converts particle energy to radiation energy.
+The DRPA is still robust with radiation, and the Lorentz factor of the most
+high energy particles reach more than two thousand before they decouple from
+the electromagnetic pulse. Resulted emitted power from the pulse front is lower
+in the radiative case than the estimation from the non-radiative case due to
+the radiation damping. The emitted radiation is strongly linearly polarized and
+peaked within few degrees from the direction of Poynting flux.",0504561v1
+1999-05-06,Collective and chaotic motion in self-bound many-body systems,"We investigate the interplay of collective and chaotic motion in a classical
+self-bound N-body system with two-body interactions. This system displays a
+hierarchy of three well separated time scales that govern the onset of chaos,
+damping of collective motion and equilibration. Comparison with a mean-field
+problem shows that damping is mainly due to dephasing. The Lyapunov exponent,
+damping and equilibration rates depend mildly on the system size N.",9905007v2
+1997-05-12,Damping of Oscillations in Layer-by-Layer Growth,"We present a theory for the damping of layer-by-layer growth oscillations in
+molecular beam epitaxy. The surface becomes rough on distances larger than a
+layer coherence length which is substantially larger than the diffusion length.
+The damping time can be calculated by a comparison of the competing roughening
+and smoothening mechanisms. The dependence on the growth conditions,
+temperature and deposition rate, is characterized by a power law. The
+theoretical results are confirmed by computer simulations.",9705100v1
+1999-09-17,Thermoelastic Damping in Micro- and Nano-Mechanical Systems,"The importance of thermoelastic damping as a fundamental dissipation
+mechanism for small-scale mechanical resonators is evaluated in light of recent
+efforts to design high-Q micrometer- and nanometer-scale electro-mechanical
+systems (MEMS and NEMS). The equations of linear thermoelasticity are used to
+give a simple derivation for thermoelastic damping of small flexural vibrations
+in thin beams. It is shown that Zener's well-known approximation by a
+Lorentzian with a single thermal relaxation time slightly deviates from the
+exact expression.",9909271v1
+2000-10-01,Super-Radiance and the Unstable Photon Oscillator,"If the damping of a simple harmonic oscillator from a thermally random force
+is sufficiently strong, then the oscillator may become unstable. For a photon
+oscillator (radiatively damped by electric dipole moments), the instability
+leads to a low temperature Hepp-Lieb-Preparata super-radiant phase transition.
+The stable oscillator regime is described by the free energy of the
+conventional Casimir effect. The unstable (strongly damped) oscillator has a
+free energy corresponding to Dicke super-radiance.",0010013v1
+2001-08-07,Non-damped Acoustic Plasmon and Superconductivity in Single Wall Carbon Nanotubes,"We show that non-damped acoustic plasmons exist in single wall carbon
+nanotubes (SWCNT) and propose that the non-damped acoustic plasmons may mediate
+electron-electron attraction and result in superconductivity in the SWCNT. The
+superconducting transition temperature Tc for the SWCNT (3,3) obtained by this
+mechanism agrees with the recent experimental result (Z. K. Tang et al, Science
+292, 2462(2001)). We also show that it is possible to get higher Tc up to 99 K
+by doping the SWCNT (5,5).",0108124v2
+2001-12-16,The Damping of the Bose-Condensate Oscillations in a Trap at Zero Temperature,"We discuss an existence of the damping for the radial condensate oscillations
+in a cylindric trap at zero temperature. The damping is a result of the
+parametric resonance leading to energy transfer from the coherent condensate
+oscillations to the longitudinal sound waves within a finite frequency
+interval. The parametric resonance is due to the oscillations of the sound
+velocity. The triggering amplitudes at zero temperature are associated with the
+zero-point oscillations.",0112292v1
+2002-06-13,Beliaev damping of quasi-particles in a Bose-Einstein condensate,"We report a measurement of the suppression of collisions of quasi-particles
+with ground state atoms within a Bose-Einstein condensate at low momentum.
+These collisions correspond to Beliaev damping of the excitations, in the
+previously unexplored regime of the continuous quasi-particle energy spectrum.
+We use a hydrodynamic simulation of the expansion dynamics, with the Beliaev
+damping cross-section, in order to confirm the assumptions of our analysis.",0206234v1
+2002-06-28,Accidental suppression of Landau damping of the transverse breathing mode in elongated Bose-Einstein condensates,"We study transverse radial oscillations of an elongated Bose-Einstein
+condensate using finite temperature simulations, in the context of a recent
+experiment at ENS. We demonstrate the existence of a mode corresponding to an
+in-phase collective oscillation of both the condensate and thermal cloud.
+Excitation of this mode accounts for the very small damping rate observed
+experimentally, and we find excellent quantitative agreement between experiment
+and theory. In contrast to other condensate modes, interatomic collisions are
+found to be the dominant damping mechanism in this case.",0206582v1
+2005-03-03,Collapse of thermal activation in moderately damped Josephson junctions,"We study switching current statistics in different moderately damped
+Josephson junctions: a paradoxical collapse of the thermal activation with
+increasing temperature is reported and explained by interplay of two
+conflicting consequences of thermal fluctuations, which can both assist in
+premature escape and help in retrapping back into the stationary state. We
+analyze the influence of dissipation on the thermal escape by tuning the
+damping parameter with a gate voltage, magnetic field, temperature and an
+in-situ capacitor.",0503067v1
+2006-03-13,Universal features of the defect-induced damping of lattice vibrations,"It is shown that any defect gives an Ohmic contribution to the damping of any
+normal mode of the crystal lattice with nonzero wavevector which does not
+vanish at zero temperature. This explains the large phason damping observed at
+low temperatures in incommensurate phases, and might be a key factor to
+understand the linear-in-$T$ specific heat observed in a number of real
+dielectrics at low enough temperatures.",0603343v2
+2006-04-25,Spin Precession and Avalanches,"In many magnetic materials, spin dynamics at short times are dominated by
+precessional motion as damping is relatively small. In the limit of no damping
+and no thermal noise, we show that for a large enough initial instability, an
+avalanche can transition to an ergodic phase where the state is equivalent to
+one at finite temperature, often above that for ferromagnetic ordering. This
+dynamical nucleation phenomenon is analyzed theoretically. For small finite
+damping the high temperature growth front becomes spread out over a large
+region. The implications for real materials are discussed.",0604563v1
+2007-02-11,Non-Markovian coherence dynamics of driven spin boson model: damped quantum beat or large amplitude coherence oscillation,"The dynamics of driven spin boson model is studied analytically by means of
+the perturbation approach based on a unitary transformation. We gave the
+analytical expression for the population difference and coherence of the two
+level system. The results show that in the weak driven case, the population
+difference present damped coherent oscillation (single or double frequency) and
+the frequencies depend on the initial state. The coherence exhibit damped
+oscillation with Rabi frequency. When driven field is strong enough, the
+population difference exhibit undamped large-amplitude coherent oscillation.
+The results easily return to the two extreme cases without dissipation or
+without periodic driven.",0702268v1
+2006-05-01,Stability and quasinormal modes of the massive scalar field around Kerr black holes,"We find quasinormal spectrum of the massive scalar field in the background of
+the Kerr black holes. We show that all found modes are damped under the
+quasinormal modes boundary conditions when $\mu M$ is not large, thereby
+implying stability of the massive scalar field. This complements the region of
+stability determined by the Beyer inequality for large masses of the field. We
+show that, similar to the case of a non-rotating black holes, the massive term
+of the scalar field does not contribute in the regime of high damping. Thereby,
+the high damping asymptotic should be the same as for the massless scalar
+field.",0605013v1
+1992-04-06,Comment on ``High Temperature Fermion Propagator -- Resummation and Gauge Dependence of the Damping Rate'',"Baier et al. have reported the damping rate of long-wavelength fermionic
+excitations in high-temperature QED and QCD to be gauge-fixing-dependent even
+within the resummation scheme due to Braaten and Pisarski. It is shown that
+this problem is caused by the singular nature of the on-shell expansion of the
+fermion self-energy in the infra-red. Its regularization reveals that the
+alleged gauge dependence pertains to the residue rather than the pole of the
+fermion propagator, so that in particular the damping constant comes out
+gauge-independent, as it should.",9204210v1
+1993-02-09,Damping rates for moving particles in hot QCD,"Using a program of perturbative resummation I compute the damping rates for
+fields at nonzero spatial momentum to leading order in weak coupling in hot
+$QCD$. Sum rules for spectral densities are used to simplify the calculations.
+For massless fields the damping rate has an apparent logarithmic divergence in
+the infrared limit, which is cut off by the screening of static magnetic fields
+(``magnetic mass''). This demonstrates how at high temperature even
+perturbative quantities are sensitive to nonperturbative phenomenon.",9302242v1
+1994-04-21,Is \lq\lq Heavy Quark Damping Rate Puzzle'' in Hot QCD Really the Puzzle?,"Within the framework of perturbative resummation scheme of Pisarski and
+Braaten, the decay- or damping-rate of a moving heavy quark (muon) to leading
+order in weak coupling in hot QCD (QED) is examined. Although, as is well
+known, the conventionally-defined damping rate diverges logarithmically at the
+infrared limit, shown is that no such divergence appears in the physically
+measurable decay rate. The cancellation occurs between the contribution from
+the \lq\lq real'' decay diagram and the contribution from the diagrams with
+\lq\lq thermal radiative correction''.",9404318v1
+1996-01-12,Damping Rate of a Scalar Particle in Hot Scalar QED,"In contrast to the damping of partons in a quark-gluon plasma, the damping of
+a scalar particle in a hot scalar QED plasma can be calculated to leading order
+for the whole momentum range using the Braaten-Pisarski method. In this way the
+evolution of the logarithmic infrared singularity caused by the exchange of a
+transverse photon from soft to hard momenta can be studied.",9601254v1
+1996-09-17,Damping Rate of Quasiparticles in Degenerate Ultrarelativistic Plasmas,"We compute the damping rate of a fermion in a dense relativistic plasma at
+zero temperature. Just above the Fermi sea, the damping rate is dominated by
+the exchange of soft magnetic photons (or gluons in QCD) and is proportional to
+$(E-\mu)$, where E is the fermion energy and $\mu$ the chemical potential. We
+also compute the contribution of soft electric photons and of hard photons. As
+in the nonrelativistic case, the contribution of longitudinal photons is
+proportional to $(E-\mu)^2$, and is thus non leading in the relativistic case.",9609369v1
+1997-05-28,Classical Statistical Mechanics and Landau Damping,"We study the retarded response function in scalar $\phi^4$-theory at finite
+temperature. We find that in the high-temperature limit the imaginary part of
+the self-energy is given by the classical theory to leading order in the
+coupling. In particular the plasmon damping rate is a purely classical effect
+to leading order, as shown by Aarts and Smit. The dominant contribution to
+Landau damping is given by the propagation of classical fields in a heat bath
+of non-interacting fields.",9705452v1
+1997-12-01,A potential infrared problem with the damping rates for gluons with soft momentum in hot QCD,"We calculate the damping rate $\gamma_l$ for longitudinal gluons with zero
+momentum in finite high temperature QCD and show that some of its contributing
+terms are infrared divergent. This is in contrast with the expectation that
+this damping rate is to be equal to the corresponding one $\gamma_t$ for
+transverse gluons which is known to be finite. Our calculation was motivated by
+the fact that similar divergent terms occur when we calculated in a previous
+work $\gamma_t$ to order $ p^2$, p being the momentum of the gluon. After we
+present our results, we briefly discuss them.",9712210v1
+1998-04-21,The Plasmon Damping Rate for T -> T_C,"The plasmon damping rate in scalar field theory is computed close to the
+critical temperature. It is shown that the divergent result obtained in
+perturbation theory is a consequence of neglecting the thermal renormalization
+of the coupling. Taking this effect into account, a vanishing damping rate is
+obtained, leading to the critical slowing down of the equilibration process.",9804351v2
+1998-10-06,Self-consistent Study on Color Transport in the Quark Gluon Plasma at Finite Chemical Potential,"We calculate the relaxation time self-consistently to study the damping of
+collective color modes and the color conductivity in a QGP by deriving
+self-consistent equations for the damping rates of gluons and quarks to leading
+order QCD by TFD including a chemical potential for quarks. We show that the
+damping rates are not sensitive to the chemical potential whereas color
+conductivity is enhanced considerably.",9810256v1
+1999-02-19,The problem of nonlinear Landau damping in quark-gluon plasma,"On the basis of the semiclassical equations for quark-gluon plasma (QGP) and
+Yang-Mills equation, the generalized kinetic equation for waves with regard to
+its interaction is obtained. The physical mechanisms defining nonlinear
+scattering of a plasmon by QGP particles are analysed. The problem on a
+connection of nonlinear Landau damping rate of longitudinal oscillation with
+damping rate, obtained on the basis of hard thermal loops approximation, is
+considered.",9902397v2
+1999-07-21,A Slavnov-Taylor identity and equality of damping rates for static transverse and longitudinal gluons in hot QCD,"A Slavnov-Taylor identity is derived for the gluon polarization tensor in hot
+QCD. We evaluate its implications for damping of gluonic modes in the plasma.
+Applying the identity to next to the leading order in hard-thermal-loop
+resummed perturbation theory, we derive the expected equality of damping rates
+for static transverse and longitudinal (soft) gluons. This is of interest also
+in view of deviating recent reports of $\gamma_t(p=0)\neq\gamma_l(p=0)$ based
+on a direct calculation of $\gamma_l(p=0)$.",9907439v1
+2000-09-15,Fermion Damping Rate Effects in Cold Dense Matter,"We review the non-Fermi or marginal liquid behavior of a relativistic QED
+plasma. In this medium a quasiparticle has a damping rate that depends linearly
+on the distance between its energy and the Fermi surface. We stress that this
+dependence is due to the long-range character of the magnetic interactions in
+the medium. Finally, we study how the quark damping rate modifies the gap
+equation of color superconductivity, reducing the value of the gap at the Fermi
+surface.",0009182v1
+2001-07-19,Photon Damping Caused by Electron-Positron Pair Production in a Strong Magnetic Field,"Damping of an electromagnetic wave in a strong magnetic field is analyzed in
+the kinematic region near the threshold of electron-positron pair production.
+Damping of the electromagnetic field is shown to be noticeably nonexponential
+in this region. The resulting width of the photon $\gamma \to e^+ e^-$ decay is
+considerably smaller than previously known results.",0107217v1
+2004-09-27,Damping of electromagnetic waves due to electron-positron pair production,"The problem of the backreaction during the process of electron-positron pair
+production by a circularly polarized electromagnetic wave propagating in a
+plasma is investigated. A model based on the relativistic Boltzmann-Vlasov
+equation with a source term corresponding to the Schwinger formula for the pair
+creation rate is used. The damping of the wave, the nonlinear up-shift of its
+frequency due to the plasma density increase and the effect of the damping on
+the wave polarization and on the background plasma acceleration are
+investigated as a function of the wave amplitude.",0409301v1
+2005-10-25,Infrared behavior of the dispersion relations in high-temperature scalar QED,"We investigate the infrared properties of the next-to-leading-order
+dispersion relations in scalar quantum electrodynamics at high temperature in
+the context of hard-thermal-loop perturbation theory. Specifically, we
+determine the damping rate and the energy for scalars with ultrasoft momenta.
+We show by explicit calculations that an early external-momentum expansion,
+before the Matsubara sum is performed, gives exactly the same result as a late
+one. The damping rate is obtained up to fourth order included in the ultrasoft
+momentum and the energy up to second order. The damping rate is found sensitive
+in the infrared whereas the energy not.",0510330v1
+2006-11-09,Lepton asymmetry in the primordial gravitational wave spectrum,"Effects of neutrino free streaming is evaluated on the primordial spectrum of
+gravitational radiation taking both neutrino chemical potential and masses into
+account. The former or the lepton asymmetry induces two competitive effects,
+namely, to increase anisotropic pressure, which damps the gravitational wave
+more, and to delay the matter-radiation equality time, which reduces the
+damping. The latter effect is more prominent and a large lepton asymmetry would
+reduce the damping. We may thereby be able to measure the magnitude of lepton
+asymmetry from the primordial gravitational wave spectrum.",0611121v1
+2005-03-17,A New Approach to Canonical Quantization of the Radiation Damping,"Inspired in some works about quantization of dissipative systems, in
+particular of the damped harmonic oscillator\cite{MB,RB,12}, we consider the
+dissipative system of a charge interacting with its own radiation, which
+originates the radiation damping (RD). Using the indirect Lagrangian
+representation we obtained a Lagrangian formalism with a Chern-Simons-like
+term. A Hamiltonian analysis is also done, what leads to the quantization of
+the system.",0503135v1
+2004-06-02,Instability results for the damped wave equation in unbounded domains,"We extend some previous results for the damped wave equation in bounded
+domains in Euclidean spaces to the unbounded case. In particular, we show that
+if the damping term is of the form $\alpha a$ with bounded $a$ taking on
+negative values on a set of positive measure, then there will always exist
+unbounded solutions for sufficiently large positive $\alpha$.
+  In order to prove these results, we generalize some existing results on the
+asymptotic behaviour of eigencurves of one-parameter families of Schrodinger
+operators to the unbounded case, which we believe to be of interest in their
+own right.",0406041v1
+2002-12-11,Rotational Damping and Compound Formation in Warm Rotating Nuclei,"The rotational damping width \Gamma_{rot} and the compound damping width
+\Gamma_{comp} are two fundamental quantities that characterize rapidly rotating
+compound nuclei having finite thermal excitation energy. A two-component
+structure in the strength function of consecutive E2 transitions reflects the
+two widths, and it causes characteristic features in the double and triple
+gamma-ray spectra. We discuss a new method to extract experimentally values of
+\Gamma_{rot} and \Gamma_{comp}. The first preliminary result of this method is
+presented.",0212050v1
+2003-07-27,Chaos and rotational damping in particle-rotor model,"The onset of chaos and the mechanism of rotational damping are studied in an
+exactly soluble particle-rotor model. It is shown that the degree of chaoticity
+as inferred from the statistical measures is closely related to the onset of
+rotational damping obtained using the model Hamiltonian.",0307104v2
+1997-07-10,Supersymmetric partner chirping of Newtonian free damping,"We connect the classical free damping cases by means of Rosner's construction
+in supersymmetric quantum mechanics. Starting with the critical damping, one
+can obtain in the underdamping case a chirping of instantaneous physical
+frequency \omega ^{2}(t) \propto \omega_{u}^{2}sech^2(\omega_{u}t), whereas in
+the overdamped case the ""chirping"" is of the (unphysical) type \omega
+^{2}(t)\propto\omega_{o}^{2}sec^{2}(\omega_{o}t), where \omega_{u}$ and
+$\omega_{o} are the underdamped and overdamped frequency parameters,
+respectively",9707012v4
+2000-04-10,Ermakov-Lewis angles for one-parameter supersymmetric families of Newtonian free damping modes,"We apply the Ermakov-Lewis procedure to the one-parameter damped modes
+\tilde{y} recently introduced by Rosu and Reyes, which are related to the
+common Newtonian free damping modes y by the general Riccati solution [H.C.
+Rosu and M. Reyes, Phys. Rev. E 57, 4850 (1998), physics/9707019]. In
+particular, we calculate and plot the angle quantities of this approach that
+can help to distinguish these modes from the common y modes",0004014v4
+2002-10-29,Model of Internal Friction Damping in Solids,"A model for harmonic oscillator damping due to the internal friction of
+solids has been developed, based on considerations of a long period pendulum.
+The assumption of a complex elastic modulus to describe stress-strain
+hysteresis in the support structure of the pendulum yields an expression for
+the figure of merit Q that agrees with many experiments involving material
+damping. As such, the approximations of this linear model stand in contrast
+with common theory.",0210121v1
+2003-06-11,Nonlinear Damping of the 'Linear' Pendulum,"This study shows that typical pendulum dynamics is far from the simple
+equation of motion presented in textbooks. A reasonably complete damping model
+must use nonlinear terms in addition to the common linear viscous expression.
+In some cases a nonlinear substitute for assumed linear damping may be more
+appropriate. Even for exceptional cases where all nonlinearity may be ignored,
+it is shown that viscous dissipation involves subtleties that can lead to huge
+errors when ignored.",0306081v1
+2003-07-02,Harmonic Oscillator Potential to describe Internal Dissipation,"Assuming that a constant potential energy function has meaning for a
+dissipated harmonic oscillator, then an important issue is the time dependence
+of the turning points. Turning point studies demonstrate that the common model
+of external (viscous) damping fails to properly describe those many systems
+where structural (internal friction) damping is the most important source of
+dissipation. For internal friction damping, the better model of potential
+energy is one in which the function is not stationary.",0307016v1
+2004-08-19,Beyond the Linear Damping Model for Mechanical Harmonic Oscillators,"The steady state motion of a folded pendulum has been studied using
+frequencies of drive that are mainly below the natural (resonance) frequency of
+the instrument. Although the free-decay of this mechanical oscillator appears
+textbook exponential, the steady state behavior of the instrument for
+sub-resonance drive can be remarkably complex. Although the response cannot be
+explained by linear damping models, the general features can be understood with
+the nonlinear, modified Coulomb damping model developed by the author.",0408091v1
+1998-01-28,Phenomenological damping in trapped atomic Bose-Einstein condensates,"The method of phenomenological damping developed by Pitaevskii for
+superfluidity near the $\lambda$ point is simulated numerically for the case of
+a dilute, alkali, inhomogeneous Bose-condensed gas near absolute zero. We study
+several features of this method in describing the damping of excitations in a
+Bose-Einstein condensate. In addition, we show that the method may be employed
+to obtain numerically accurate ground states for a variety of trap potentials.",9801064v1
+1998-04-06,Optimal quantum codes for preventing collective amplitude damping,"Collective decoherence is possible if the departure between quantum bits is
+smaller than the effective wave length of the noise field. Collectivity in the
+decoherence helps us to devise more efficient quantum codes. We present a class
+of optimal quantum codes for preventing collective amplitude damping to a
+reservoir at zero temperature. It is shown that two qubits are enough to
+protect one bit quantum information, and approximately $L+ 1/2 \log_2((\pi
+L)/2)$ qubits are enough to protect $L$ qubit information when $L$ is large.
+For preventing collective amplitude damping, these codes are much more
+efficient than the previously-discovered quantum error correcting or avoiding
+codes.",9804014v1
+2000-01-12,Antibunching effect of the radiation field in a microcavity with a mirror undergoing heavily damping oscillation,"The interaction between the radiation field in a microcavity with a mirror
+undergoing damping oscillation is investigated. Under the heavily damping
+cases, the mirror variables are adiabatically eliminated.
+  The the stationary conditions of the system are discussed. The small
+fluctuation approximation around steady values is applied to analysis the
+antibunching effect of the cavity field. The antibunching condition is given
+under two limit cases.",0001036v1
+2000-03-29,Disagreement between correlations of quantum mechanics and stochastic electrodynamics in the damped parametric oscillator,"Intracavity and external third order correlations in the damped nondegenerate
+parametric oscillator are calculated for quantum mechanics and stochastic
+electrodynamics (SED), a semiclassical theory. The two theories yield greatly
+different results, with the correlations of quantum mechanics being cubic in
+the system's nonlinear coupling constant and those of SED being linear in the
+same constant. In particular, differences between the two theories are present
+in at least a mesoscopic regime. They also exist when realistic damping is
+included. Such differences illustrate distinctions between quantum mechanics
+and a hidden variable theory for continuous variables.",0003131v1
+2002-02-15,Decoherence of Quantum Damped Oscillators,"Quantum dissipation is studied within two model oscillators, the
+Caldirola-Kanai (CK) oscillator as an open system with one degree of freedom
+and the Bateman-Feshbach-Tikochinsky (BFT) oscillator as a closed system with
+two degrees of freedom. Though these oscillators describe the same classical
+damped motion, the CK oscillator retains the quantum coherence, whereas the
+damped subsystem of the BFT oscillator exhibits both quantum decoherence and
+classical correlation. Furthermore the amplified subsystem of the BFT
+oscillator shows the same degree of quantum decohernce and classical
+correlation.",0202089v1
+2002-12-05,Time correlated quantum amplitude damping channel,"We analyze the problem of sending classical information through qubit
+channels where successive uses of the channel are correlated. This work extends
+the analysis of C. Macchiavello and G. M. Palma to the case of a non-Pauli
+channel - the amplitude damping channel. Using the channel description outlined
+in S. Daffer, et al, we derive the correlated amplitude damping channel. We
+obtain a similar result to C. Macchiavello and G. M. Palma, that is, that under
+certain conditions on the degree of channel memory, the use of entangled input
+signals may enhance the information transmission compared to the use of product
+input signals.",0212032v1
+2005-06-01,Quantum damped oscillator I: dissipation and resonances,"Quantization of a damped harmonic oscillator leads to so called Bateman's
+dual system. The corresponding Bateman's Hamiltonian, being a self-adjoint
+operator, displays the discrete family of complex eigenvalues. We show that
+they correspond to the poles of energy eigenvectors and the corresponding
+resolvent operator when continued to the complex energy plane. Therefore, the
+corresponding generalized eigenvectors may be interpreted as resonant states
+which are responsible for the irreversible quantum dynamics of a damped
+harmonic oscillator.",0506007v1
+2005-10-19,The damped harmonic oscillator in deformation quantization,"We propose a new approach to the quantization of the damped harmonic
+oscillator in the framework of deformation quantization. The quantization is
+performed in the Schr\""{o}dinger picture by a star-product induced by a
+modified ""Poisson bracket"". We determine the eigenstates in the damped regime
+and compute the transition probability between states of the undamped harmonic
+oscillator after the system was submitted to dissipation.",0510150v1
+2006-04-28,The characteristic function of optical evolution,"The master equation of quantum optical density operator is transformed to the
+equation of characteristic function. The parametric amplification and amplitude
+damping as well as the phase damping are considered. The solution for the most
+general initial quantum state is obtained for parametric amplification and
+amplitude damping. The purity of one mode Gaussian system and the entanglement
+of two mode Gaussian system are studied.",0604208v4
+2007-01-13,Wave-particle duality in the damped harmonic oscillator,"Quantization of the damped harmonic oscillator is taken as leitmotiv to
+gently introduce elements of quantum probability theory for physicists. To this
+end, we take (graduate) students in physics as entry level and explain the
+physical intuition and motivation behind the, sometimes overwhelming, math
+machinery of quantum probability theory.
+  The main text starts with the quantization of the (undamped) harmonic
+oscillator from the Heisenberg and Schroedinger point of view. We show how both
+treatments are special instances of a quantum probabilistic quantization
+procedure: the second quantization functor. We then apply the second
+quantization functor to the damped harmonic oscillator and interpret the
+quantum dynamics of the position and energy operator as stochastic processes.",0701082v1
+2007-04-11,Time dependence of joint entropy of oscillating quantum systems,"The time dependent entropy (or Leipnik's entropy) of harmonic and damped
+harmonic oscillators is extensively investigated by using time dependent wave
+function obtained by the Feynman path integral method. Our results for simple
+harmonic oscillator are in agrement with the literature. However, the joint
+entropy of damped harmonic oscillator shows remarkable discontinuity with time
+for certain values of damping factor. According to the results, the envelop of
+the joint entropy curve increases with time monotonically. This results is the
+general properties of the envelop of the joint entropy curve for quantum
+systems.",0704.1370v3
+2007-06-30,The squeezed generalized amplitude damping channel,"Squeezing of a thermal bath introduces new features absent in an open quantum
+system interacting with an uncorrelated (zero squeezing) thermal bath. The
+resulting dynamics, governed by a Lindblad-type evolution, extends the concept
+of a generalized amplitude damping channel, which corresponds to a dissipative
+interaction with a purely thermal bath. Here we present the Kraus
+representation of this map, which we call the squeezed generalized amplitude
+damping channel. As an application of this channel to quantum information, we
+study the classical capacity of this channel.",0707.0059v2
+2007-07-09,Memory in a nonlocally damped oscillator,"We analyze the new equation of motion for the damped oscillator. It differs
+from the standard one by a damping term which is nonlocal in time and hence it
+gives rise to a system with memory. Both classical and quantum analysis is
+performed. The characteristic feature of this nonlocal system is that it breaks
+local composition low for the classical Hamiltonian dynamics and the
+corresponding quantum propagator.",0707.1199v2
+2007-07-20,Dynamics of Bloch Oscillations in Disordered Lattice Potentials,"We present a detailed analysis of the dynamics of Bloch oscillations of
+Bose-Einstein condensates in disordered lattice potentials. Due to the disorder
+and the interparticle interactions these oscillations undergo a dephasing,
+reflected in a damping of the center of mass oscillations, which should be
+observable under realistic experimental conditions. The interplay between
+interactions and disorder is far from trivial, ranging from an
+interaction-enhanced damping due to modulational instability for strong
+interactions, to an interaction-reduced damping due to a dynamical screening of
+the disorder potential.",0707.3131v1
+2007-09-14,Damping of field-induced chemical potential oscillations in ideal two-band compensated metals,"The field and temperature dependence of the de Haas-van Alphen oscillations
+spectrum is studied for an ideal two-dimensional compensated metal. It is shown
+that the chemical potential oscillations, involved in the frequency
+combinations observed in the case of uncompensated orbits, are strongly damped
+and can even be suppressed when the effective masses of the electron- and
+hole-type orbits are the same. When magnetic breakdown between bands occurs,
+this damping is even more pronounced and the Lifshits-Kosevich formalism
+accounts for the data in a wide field range.",0709.2223v2
+2007-09-14,Update on Ion Studies,"The effect of ions has received one of the highest priorities in R&D for the
+damping rings of the International Linear Collider(ILC). It is detrimental to
+the performance of the electron damping ring. In this note, an update
+concerning the ion studies for the ILC damping ring is given. We investigate
+the gap role and irregular fill pattern in the ring.The ion density reduction
+in different fills is calculated analytically. Simulation results are also
+presented.",0709.2248v1
+2007-10-03,Stability of a Nonlinear Axially Moving String With the Kelvin-Voigt Damping,"In this paper, a nonlinear axially moving string with the Kelvin-Voigt
+damping is considered. It is proved that the string is stable, i.e., its
+transversal displacement converges to zero when the axial speed of the string
+is less than a certain critical value. The proof is established by showing that
+a Lyapunov function corresponding to the string decays to zero exponentially.
+It is also shown that the string displacement is bounded when a bounded
+distributed force is applied to it transversally. Furthermore, a few open
+problems regarding the stability and stabilization of strings with the
+Kelvin-Voigt damping are stated.",0710.0872v1
+2007-10-15,General Solution of the Quantum Damped Harmonic Oscillator,"In this paper the general solution of the quantum damped harmonic oscillator
+is given.",0710.2724v4
+2008-02-21,Identification of Test Structures for Reduced Order Modeling of the Squeeze Film Damping in Mems,"In this study the dynamic behaviour of perforated microplates oscillating
+under the effect of squeeze film damping is analyzed. A numerical approach is
+adopted to predict the effects of damping and stiffness transferred from the
+surrounding ambient air to oscillating structures ; the effect of hole's cross
+section and plate's extension is observed. Results obtained by F.E.M. models
+are compared with experimental measurements performed by an optical
+interferometric microscope.",0802.3076v1
+2008-03-14,Current-induced noise and damping in non-uniform ferromagnets,"In the presence of spatial variation of the magnetization direction, electric
+current noise causes a fluctuating spin-transfer torque that increases the
+fluctuations of the ferromagnetic order parameter. By the
+fluctuation-dissipation theorem, the equilibrium fluctuations are related to
+the magnetization damping, which in non-uniform ferromagnets acquires a
+nonlocal tensor structure. In biased ferromagnets, shot noise can become the
+dominant contribution to the magnetization noise at low temperatures.
+Considering spin spirals as a simple example, we show that the current-induced
+noise and damping is significant.",0803.2175v1
+2008-04-23,Ion acoustic waves in the plasma with the power-law q-distribution in nonextensive statistics,"We investigate the dispersion relation and Landau damping of ion acoustic
+waves in the collisionless magnetic-field-free plasma if it is described by the
+nonextensive q-distributions of Tsallis statistics. We show that the increased
+numbers of superthermal particles and low velocity particles can explain the
+strengthened and weakened modes of Landau damping, respectively, with the
+q-distribution. When the ion temperature is equal to the electron temperature,
+the weakly damped waves are found to be the distributions with small values of
+q.",0804.3732v1
+2008-07-23,Tunneling-induced damping of phase coherence revivals in deep optical lattices,"We consider phase coherence collapse and revival in deep optical lattices,
+and calculate within the Bose-Hubbard model the revival amplitude damping
+incurred by a finite tunneling coupling of the lattice wells (after sweeping
+from the superfluid to the Mott phase). Deriving scaling laws for the
+corresponding decay of first-order coherence revival in terms of filling
+factor, final lattice depth, and number of tunneling coupling partners, we
+estimate whether revival-damping related to tunneling between sites can be or
+even has already been observed in experiment.",0807.3627v2
+2008-07-31,Generalized Theory of Landau Damping,"Collisionless damping of electrical waves in plasma is investigated in the
+frame of the classical formulation of the problem. The new principle of
+regularization of the singular integral is used. The exact solution of the
+corresponding dispersion equation is obtained. The results of calculations lead
+to existence of discrete spectrum of frequencies and discrete spectrum of
+dispersion curves. Analytical results are in good coincidence with results of
+direct mathematical experiments. Key words: Foundations of the theory of
+transport processes and statistical physics; Boltzmann physical kinetics;
+damping of plasma waves, linear theory of wave`s propagation PACS: 67.55.Fa,
+67.55.Hc",0807.5007v1
+2008-08-05,"Radiation damping, noncommutativity and duality","In this work, our main objective is to construct a N=2 supersymmetric
+extension of the nonrelativistic $(2+1)$-dimensional model describing the
+radiation damping on the noncommutative plane with scalar (electric) and vector
+(magnetic) interactions by the N=2 superfield technique. We also introduce a
+dual equivalent action to the radiation damping one using the Noether
+procedure.",0808.0694v2
+2008-10-06,Local existence and exponential growth for a semilinear damped wave equation with dynamic boundary conditions,"In this paper we consider a multi-dimensional damped semiliear wave equation
+with dynamic boundary conditions, related to the Kelvin-Voigt damping. We
+firstly prove the local existence by using the Faedo-Galerkin approximations
+combined with a contraction mapping theorem. Secondly, the exponential growth
+of the energy and the $L^p$ norm of the solution is presented.",0810.1013v1
+2008-11-20,An explanation for the pseudogap of high-temperature superconductors based on quantum optics,"We first explain the pseudogap of high-temperature superconductivity based on
+an approach of quantum optics. After introducing a damping factor for the
+lifetime $\tau$ of quasiparticles, the superconducting dome is naturally
+produced, and the pseudogap is the consequence of pairing with damped
+coherence. We derive a new expression of Ginzburg-Landau free energy density,
+in which a six-order term due to decoherence damping effect is included.
+Without invoking any microscopic pairing mechanism, this approach provides a
+simple universal equation of second-order phase transition, which can be
+reduced to two well-known empirical scaling equations: the superconducting dome
+Presland-Tallon equation, and the normal-state pseudogap crossover temperature
+$T^{*}$ line.",0811.3262v1
+2008-12-18,Exponential decay for solutions to semilinear damped wave equation,"This paper is concerned with decay estimate of solutions to the semilinear
+wave equation with strong damping in a bounded domain. Introducing an
+appropriate Lyaponuv function, we prove that when the damping is linear, we can
+find initial data, for which the solution decays exponentially. This result
+improves an early one in an article of Gazzola and Squassina.",0812.3637v3
+2009-05-27,Difference between penetration and damping lengths in photonic crystal mirrors,"Different mirror geometries in two-dimensional photonic crystal slabs are
+studied with fully-vectorial calculations. We compare their optical properties
+and, in particular, we show that, for heterostructure mirrors, the penetration
+length associated with the delay induced by distributed reflection is not
+correlated to the characteristic damping length of the electromagnetic energy
+distribution in the mirror. This unexpected result evidences that the usual
+trade-off between short damping lengths and large penetration lengths that is
+classically encountered in distributed Bragg reflectors can be overcome with
+carefully designed photonic crystal structures.",0905.4449v2
+2009-06-01,Exponential Decay Rates for the Damped Korteweg-de Vries Type Equation,"The exponential decay rate of $L^2-$norm related to the Korteweg-de Vries
+equation with localized damping posed on whole real line will be established.
+In addition, by using classical arguments we determine the $H^1-$norm of the
+solution associated to Korteweg-de Vries equation with damping in whole domain,
+can not have a decay property for an arbitrary initial data.",0906.0285v2
+2009-07-02,Damping and decoherence of a nanomechanical resonator due to a few two level systems,"We consider a quantum model of a nanomechanical flexing beam resonator
+interacting with a bath comprising a few damped tunneling two level systems
+(TLS's). In contrast with a resonator interacting bilinearly with an ohmic free
+oscillator bath (modeling clamping loss, for example), the mechanical resonator
+damping is amplitude dependent, while the decoherence of quantum superpositions
+of mechanical position states depends only weakly on their spatial separation.",0907.0431v1
+2009-07-29,High performance single-error-correcting quantum codes for amplitude damping,"We construct families of high performance quantum amplitude damping codes.
+All of our codes are nonadditive and most modestly outperform the best possible
+additive codes in terms of encoded dimension. One family is built from
+nonlinear error-correcting codes for classical asymmetric channels, with which
+we systematically construct quantum amplitude damping codes with parameters
+better than any prior construction known for any block length n > 7 except
+n=2^r-1. We generalize this construction to employ classical codes over GF(3)
+with which we numerically obtain better performing codes up to length 14.
+Because the resulting codes are of the codeword stabilized (CWS) type, easy
+encoding and decoding circuits are available.",0907.5149v1
+2009-10-12,Suppression of Landau damping via electron band gap,"The pondermotive potential in the X-ray Raman compression can generate an
+electron band gap which suppresses the Landau damping. The regime is identified
+where a Langmuir wave can be driven without damping in the stimulated Raman
+compression. It is shown that the partial wave breaking and the frequency
+detuning due to the trapped particles would be greatly reduced.",0910.2196v3
+2009-10-27,Rabi type oscillations in damped single 2D-quantum dot,"We present a quantized model of harmonically confined dot atom with inherent
+damping in the presence of a transverse magnetic field. The model leads to a
+non hermitian Hamiltonian in real coordinate. We have analytically studied the
+effects that damping has on the Rabi type oscillations of the system. The model
+explains the decoherence of Rabi oscillation in a Josephson Junction.",0910.5184v1
+2009-12-16,Toward a dynamical shift condition for unequal mass black hole binary simulations,"Moving puncture simulations of black hole binaries rely on a specific gauge
+choice that leads to approximately stationary coordinates near each black hole.
+Part of the shift condition is a damping parameter, which has to be properly
+chosen for stable evolutions. However, a constant damping parameter does not
+account for the difference in mass in unequal mass binaries. We introduce a
+position dependent shift damping that addresses this problem. Although the
+coordinates change, the changes in the extracted gravitational waves are small.",0912.3125v1
+2010-03-09,Damping of Nanomechanical Resonators,"We study the transverse oscillatory modes of nanomechanical silicon nitride
+strings under high tensile stress as a function of geometry and mode index m <=
+9. Reproducing all observed resonance frequencies with classical elastic theory
+we extract the relevant elastic constants. Based on the oscillatory local
+strain we successfully predict the observed mode-dependent damping with a
+single frequency independent fit parameter. Our model clarifies the role of
+tensile stress on damping and hints at the underlying microscopic mechanisms.",1003.1868v1
+2010-03-24,Global attractors for strongly damped wave equations with displacement dependent damping and nonlinear source term of critical exponent,"In this paper the long time behaviour of the solutions of 3-D strongly damped
+wave equation is studied. It is shown that the semigroup generated by this
+equation possesses a global attractor in H_{0}^{1}(\Omega)\times L_{2}(\Omega)
+and then it is proved that this global attractor is a bounded subset of
+H^{2}(\Omega)\times H^{2}(\Omega) and also a global attractor in
+H^{2}(\Omega)\cap H_{0}^{1}(\Omega)\times H_{0}^{1}(\Omega).",1003.4760v3
+2010-04-12,Entanglement properties of optical coherent states under amplitude damping,"Through concurrence, we characterize the entanglement properties of optical
+coherent-state qubits subject to an amplitude damping channel. We investigate
+the distillation capabilities of known error correcting codes and obtain upper
+bounds on the entanglement depending on the non-orthogonality of the coherent
+states and the channel damping parameter. This work provides a first, full
+quantitative analysis of these photon-loss codes which are naturally
+reminiscent of the standard qubit codes against Pauli errors.",1004.1931v2
+2010-05-20,Nonclassical phase-space trajectories for the damped harmonic quantum oscillator,"The phase-space path-integral approach to the damped harmonic oscillator is
+analyzed beyond the Markovian approximation. It is found that pairs of
+nonclassical trajectories contribute to the path-integral representation of the
+Wigner propagating function. Due to the linearity of the problem, the sum
+coordinate of a pair still satisfies the classical equation of motion.
+Furthermore, it is shown that the broadening of the Wigner propagating function
+of the damped oscillator arises due to the time-nonlocal interaction mediated
+by the heat bath.",1005.3839v1
+2010-06-09,Self frequency-locking of a chain of oscillators,"The paper studies the vibrational modes of a slightly damped uniform chain,
+with n masses coupled by elastic forces. It will be shown that, for certain
+lengths of the chain, that is for certain values of n, the damping of one of
+the masses at a specific position in the chain is able to constrain the
+vibration of the system to oscillate at a specific frequency. The damped mass
+turns out to be a node of the chain, subdividing it in two parts. This node can
+be considered as the synchronization element of the two subchains. As a
+consequence the oscillating system of n-masses is self-locking to the
+synchronized frequency of its subchains.",1006.1722v1
+2010-08-20,First principles quasiparticle damping rates in bulk lead,"First principles calculations of the damping rates (inverse inelastic
+lifetimes) of low energy quasiparticles in bulk Pb are presented. Damping rates
+are obtained both for excited electrons and holes with energies up to 8 eV on a
+set of k vectors throughout the Brillouin zone (BZ). Strong localization
+effects in the calculated lifetimes are found. Averaged over the BZ inelastic
+lifetimes versus quasiparticle energy are reported as well. In addition, the
+effect of the spin-orbit induced splitting in the band structure on the
+calculated lifetimes in Pb is investigated.",1008.3415v1
+2011-03-18,Single File Diffusion of particles with long ranged interactions: damping and finite size effects,"We study the Single File Diffusion (SFD) of a cyclic chain of particles that
+cannot cross each other, in a thermal bath, with long ranged interactions, and
+arbitrary damping. We present simulations that exhibit new behaviors
+specifically associated to systems of small number of particles and to small
+damping. In order to understand those results, we present an original analysis
+based on the decomposition of the particles motion in the normal modes of the
+chain. Our model explains all dynamic regimes observed in our simulations, and
+provides convincing estimates of the crossover times between those regimes.",1103.3642v1
+2011-04-21,Spin Damping Monopole,"We present theoretical evidence that a magnetic monopole emerges in dynamic
+magnetic systems in the presence of the spin-orbit interaction. The monopole
+field is expressed in terms of spin damping associated with magnetization
+dynamics. We demonstrate that the observation of this spin damping monopole is
+accomplished electrically using Ampere's law for monopole current. Our
+discovery suggests the integration of monopoles into electronics, namely,
+monopolotronics.",1104.4215v2
+2011-08-16,Long time dynamics for forced and weakly damped KdV on the torus,"The forced and weakly damped Korteweg-de Vries (KdV) equation with periodic
+boundary conditions is considered. Starting from $L^2$ and mean-zero initial
+data we prove that the solution decomposes into two parts; a linear one which
+decays to zero as time goes to infinity and a nonlinear one which always
+belongs to a smoother space. As a corollary we prove that all solutions are
+attracted by a ball in $H^s$, $s\in(0,1)$, whose radius depends only on $s$,
+the $L^2$ norm of the forcing term and the damping parameter. This gives a new
+proof for the existence of a smooth global attractor and provides quantitative
+information on the size of the attractor set in $H^s$.",1108.3358v1
+2011-10-12,Acceleration Control in Nonlinear Vibrating Systems based on Damped Least Squares,"A discrete time control algorithm using the damped least squares is
+introduced for acceleration and energy exchange controls in nonlinear vibrating
+systems. It is shown that the damping constant of least squares and sampling
+time step of the controller must be inversely related to insure that vanishing
+the time step has little effect on the results. The algorithm is illustrated on
+two linearly coupled Duffing oscillators near the 1:1 internal resonance. In
+particular, it is shown that varying the dissipation ratio of one of the two
+oscillators can significantly suppress the nonlinear beat phenomenon.",1110.2811v2
+2011-10-17,Normal Mode Expansion of Damped Coupled Oscillators in 3 dimensions,"In this paper, I aim to study free oscillations of a system of oscillators in
+more than one dimensions in the absence of damping. The basic approach lies in
+decoupling the motion in the individual perpendicular directions. Once the
+equations are decoupled, the existent techniques of Normal mode expansion for
+1-dimensional oscillators are used to solve for the equations of motion. I also
+study the motion of a driven system of oscillators in higher dimensions in the
+presence of a velocity dependent damping force.",1110.3773v1
+2011-10-25,Distinguishing mesoscopic quantum superpositions from statistical mixtures in periodically shaken double wells,"For Bose-Einstein condensates in double wells, N-particle Rabi-like
+oscillations often seem to be damped. Far from being a decoherence effect, the
+apparent damping can indicate the emergence of quantum superpositions in the
+many-particle quantum dynamics. However, in an experiment it would be difficult
+to distinguish the apparent damping from decoherence effects. The present paper
+suggests using controlled periodic shaking to quasi-instantaneously switch the
+sign of an effective Hamiltonian, thus implementing an `echo' technique which
+distinguishes quantum superpositions from statistical mixtures. The scheme for
+the effective time-reversal is tested by numerically solving the time-dependent
+N-particle Schrodinger equation.",1110.5444v1
+2011-11-23,Wave Propagation And Landau-Type Damping In Liquids,"Intermolecular forces are modeled by means of a modified Lennard-Jones
+potential, introducing a distance of minimum approach, and the effect of
+intermolecular interactions is accounted for with a self consistent field of
+the Vlasov type. A Vlasov equation is then written and used to investigate the
+propagation of perturbations in a liquid. A dispersion relation is obtained and
+an effect of damping, analogous to what is known in plasmas as ""Landau
+damping"", is found to take place.",1111.5519v3
+2011-11-25,Radiation Damping for Speeding-up NMR Applications,"We demonstrate theoretically and numerically how to control the NMR
+relaxation rate after application of the standard spin echo technique. Using
+radiation damping, we return the nuclear magnetization to its equilibrium state
+during a time interval that is negligible compared to the relaxation time. We
+obtain an estimate for optimal radiation damping which is consistent with our
+numerical simulations.",1111.7060v1
+2011-12-09,Perturbed damped pendulum: finding periodic solutions,"Using the damped pendulum system we introduce the averaging method to study
+the periodic solutions of a dynamical system with small perturbation. We
+provide sufficient conditions for the existence of periodic solutions with
+small amplitude of the non--linear perturbed damped pendulum. The averaging
+theory provides a useful means to study dynamical systems, accessible to Master
+and PhD students.",1112.2129v2
+2011-12-28,The role of damping for the driven anharmonic quantum oscillator,"For the model of a linearly driven quantum anharmonic oscillator, the role of
+damping is investigated. We compare the position of the stable points in phase
+space obtained from a classical analysis to the result of a quantum mechanical
+analysis. The solution of the full master equation shows that the stable points
+behave qualitatively similar to the classical solution but with small
+modifications. Both the quantum effects and additional effects of temperature
+can be described by renormalizing the damping.",1112.6119v1
+2012-01-03,Creating and studying ion acoustic waves in ultracold neutral plasmas,"We excite ion acoustic waves in ultracold neutral plasmas by imprinting
+density modulations during plasma creation. Laser-induced fluorescence is used
+to observe the density and velocity perturbations created by the waves. The
+effect of expansion of the plasma on the evolution of the wave amplitude is
+described by treating the wave action as an adiabatic invariant. After
+accounting for this effect, we determine that the waves are weakly damped, but
+the damping is significantly faster than expected for Landau damping.",1201.0786v1
+2012-03-11,Magnetic damping of a carbon nanotube NEMS resonator,"A suspended, doubly clamped single wall carbon nanotube is characterized at
+cryogenic temperatures. We observe specific switching effects in dc-current
+spectroscopy of the embedded quantum dot. These have been identified previously
+as nano-electromechanical self-excitation of the system, where positive
+feedback from single electron tunneling drives mechanical motion. A magnetic
+field suppresses this effect, by providing an additional damping mechanism.
+This is modeled by eddy current damping, and confirmed by measuring the
+resonance quality factor of the rf-driven nano-electromechanical resonator in
+an increasing magnetic field.",1203.2319v2
+2012-04-02,Random Symmetry Breaking and Freezing in Chaotic Networks,"Parameter space of a driven damped oscillator in a double well potential
+presents either a chaotic trajectory with sign oscillating amplitude or a
+non-chaotic trajectory with a fixed sign amplitude. A network of such delay
+coupled damped oscillators is shown to present chaotic dynamics while the
+amplitude sign of each damped oscillator is randomly frozen. This phenomenon of
+random broken global symmetry of the network simultaneously with random
+freezing of each degree of freedom is accompanied by the existence of
+exponentially many randomly frozen chaotic attractors with the ize of the
+network. Results are exemplified by a network of modified Duffing oscillators
+with infinite ange pseudo-inverse delayed interactions.",1204.0528v1
+2012-04-04,Nonlinear Damping in Graphene Resonators,"Based on a continuum mechanical model for single-layer graphene we propose
+and analyze a microscopic mechanism for dissipation in nanoelectromechanical
+graphene resonators. We find that coupling between flexural modes and in-plane
+phonons leads to linear and nonlinear damping of out-of-plane vibrations. By
+tuning external parameters such as bias and ac voltages, one can cross over
+from a linear to a nonlinear-damping dominated regime. We discuss the behavior
+of the effective quality factor in this context.",1204.0911v2
+2012-05-22,Heavy quark damping rate in hot viscous QCD plasma,"We derive an expression for the heavy quark damping rate in hot quark gluon
+plasma in presence of flow. Here all the bath particles here are out of
+equilibrium due to the existence of non-zero velocity gradient. The magnetic
+sector shows similar infrared divergences even after hard thermal loop
+corrections as one encounters in case of non-viscous plasma. We estimate the
+first order correction in ($\eta/s$) for heavy quark damping rate due to the
+non-zero viscosity of the QCD plasma.",1205.4895v3
+2012-07-24,Quantum capacity of an amplitude-damping channel with memory,"We calculate the quantum capacity of an amplitude-damping channel with time
+correlated Markov noise, for two channel uses. Our results show that memory of
+the channel increases it's ability to transmit quantum information
+significantly. We analyze and compare our findings with earlier numerical
+results on amplitude-damping channel with memory. An upper bound on the amount
+of quantum information transmitted over the channel in presence of memory, for
+an arbitrary number of channel uses is also presented.",1207.5612v3
+2012-08-21,Protecting quantum entanglement from amplitude damping,"Quantum entanglement is a critical resource for quantum information and
+quantum computation. However, entanglement of a quantum system is subjected to
+change due to the interaction with the environment. One typical result of the
+interaction is the amplitude damping that usually results in the reduction of
+the entanglement. Here we propose a protocol to protect quantum entanglement
+from the amplitude damping by applying Hadamard and CNOT gates. As opposed to
+some recently studied methods, the scheme presented here does not require weak
+measurement in the reversal process, leading to a faster recovery of
+entanglement. We propose a possible experimental implementation based on linear
+optical system.",1208.4187v2
+2012-10-03,Exact solutions for discrete breathers in forced-damped chain,"Exact solutions for symmetric discrete breathers (DBs) are obtained in
+forced-damped linear chain with on-site vibro-impact constraints. The damping
+is related to inelastic impacts; the forcing may be chosen from broad class of
+periodic antisymmetric functions. Global conditions for existence and stability
+of the DB are established. Some unusual phenomena, like non-monotonous
+dependence of the stability boundary on the forcing amplitude, are revealed
+analytically for the full system and illustrated numerically for small periodic
+lattices.",1210.1085v1
+2012-12-18,Using the mobile phone acceleration sensor in Physics experiments: free and damped harmonic oscillations,"The mobile acceleration sensor has been used to in Physics experiments on
+free and damped oscillations. Results for the period, frequency, spring
+constant and damping constant match very well to measurements obtained by other
+methods. The Accelerometer Monitor application for Android has been used to get
+the outputs of the sensor. Perspectives for the Physics laboratory have also
+been discussed.",1212.4403v1
+2012-12-20,How long-range interactions tune the damping in compact stars,"Long-range interactions lead to non-Fermi liquid effects in dense matter. We
+show that, in contrast to other material properties, their effect on the bulk
+viscosity of quark matter is significant since they shift its resonant maximum
+and can thereby change the viscosity by many orders of magnitude. This is of
+importance for the damping of oscillations of compact stars, like in particular
+unstable r-modes, and the quest to detect signatures of deconfined matter in
+astrophysical observations. We find that, in contrast to neutron stars with
+standard damping mechanisms, compact stars that contain ungapped quark matter
+are consistent with the observed data on low mass x-ray binaries.",1212.5242v1
+2013-02-12,Impact of gluon damping on heavy-quark quenching,"In this conference contribution, we discuss the influence of
+gluon-bremsstrahlung damping in hot, absorptive QCD matter on the heavy-quark
+radiation spectra. Within our Monte-Carlo implementation for the description of
+the heavy-quark in-medium propagation we demonstrate that as a consequence of
+gluon damping the quenching of heavy quarks becomes significantly affected at
+higher transverse momenta.",1302.2934v1
+2013-03-12,On nonlinear Schrodinger type equations with nonlinear damping,"We consider equations of nonlinear Schrodinger type augmented by nonlinear
+damping terms. We show that nonlinear damping prevents finite time blow-up in
+several situations, which we describe. We also prove that the presence of a
+quadratic confinement in all spatial directions drives the solution of our
+model to zero for large time. In the case without external potential we prove
+that the solution may not go to zero for large time due to (non-trivial)
+scattering.",1303.3033v2
+2013-06-15,A formula for damping interarea oscillations with generator redispatch,"We derive a new formula for the sensitivity of electromechanical oscillation
+damping with respect to generator redispatch. The formula could lead to some
+combination of observations, computations and heuristics to more effectively
+damp interarea oscillations.",1306.3590v2
+2013-07-24,Eigenvalue asymptotics for the damped wave equation on metric graphs,"We consider the linear damped wave equation on finite metric graphs and
+analyse its spectral properties with an emphasis on the asymptotic behaviour of
+eigenvalues. In the case of equilateral graphs and standard coupling conditions
+we show that there is only a finite number of high-frequency abscissas, whose
+location is solely determined by the averages of the damping terms on each
+edge. We further describe some of the possible behaviour when the edge lengths
+are no longer necessarily equal but remain commensurate.",1307.6377v3
+2013-08-03,Hadamard well-posedness for a hyperbolic equation of viscoelasticity with supercritical sources and damping,"Presented here is a study of a viscoelastic wave equation with supercritical
+source and damping terms. We employ the theory of monotone operators and
+nonlinear semigroups, combined with energy methods to establish the existence
+of a unique local weak solution. In addition, it is shown that the solution
+depends continuously on the initial data and is global provided the damping
+dominates the source in an appropriate sense.",1308.0720v2
+2013-10-14,Signatures of two-level defects in the temperature-dependent damping of nanomechanical silicon nitride resonators,"The damping rates of high quality factor nanomechanical resonators are well
+beyond intrinsic limits. Here, we explore the underlying microscopic loss
+mechanisms by investigating the temperature-dependent damping of the
+fundamental and third harmonic transverse flexural mode of a doubly clamped
+silicon nitride string. It exhibits characteristic maxima reminiscent of
+two-level defects typical for amorphous materials. Coupling to those defects
+relaxes the momentum selection rules, allowing energy transfer from discrete
+long wavelength resonator modes to the high frequency phonon environment.",1310.3671v1
+2013-10-25,Quenched decoherence in qubit dynamics due to strong amplitude-damping noise,"We study non-perturbatively the time evolution of a qubit subject to
+amplitude-damping noise. We show that at strong coupling the qubit decoherence
+can be quenched owing to large environment feedbacks, such that the qubit can
+evolve coherently even in the long-time limit. As an application, we show that
+for a quantum channel that consists of two independent qubits subject to
+uncorrelated local amplitude-damping noises, it can maintain at strong coupling
+finite entanglement and better than classical teleportation fidelity at long
+times.",1310.6843v2
+2013-12-19,Cyclotron dynamics of interacting bosons in artificial magnetic fields,"We study theoretically quantum dynamics of interacting bosons in artificial
+magnetic fields as engineered in recent ultracold atomic experiments, where
+quantum cyclotron orbital motion has been observed. With exact numerical
+simulations and perturbative analyses, we find that interactions induce damping
+in the cyclotron motion. The damping time is found to be dependent on
+interaction and tunneling strengths monotonically, while its dependence on
+magnetic flux is non-monotonic. Sufficiently strong interactions would render
+bosons dynamically localized inhibiting the cyclotron motion. The damping
+predicted by us can be construed as an interaction-induced quantum decoherence
+of the cyclotron motion.",1312.5747v2
+2014-01-11,Damping in two component Bose gas,"We investigate the Landau and Baliaev damping of the collective modes in a
+two-component Bose gas using the mean-field approximation. We show that due to
+the two body atom-atom interaction, oscillations of each component is coupled
+to the thermal excitations of the other component which gives rise to creation
+or destruction of the elementary excitations that can take place in the two
+separate components.In addition we find that the damping is also enhanced due
+to inter-component coupling.",1401.2537v1
+2014-04-25,The time singular limit for a fourth-order damped wave equation for MEMS,"We consider a free boundary problem modeling electrostatic
+microelectromechanical systems. The model consists of a fourth-order damped
+wave equation for the elastic plate displacement which is coupled to an
+elliptic equation for the electrostatic potential. We first review some recent
+results on existence and non-existence of steady-states as well as on local and
+global well-posedness of the dynamical problem, the main focus being on the
+possible touchdown behavior of the elastic plate. We then investigate the
+behavior of the solutions in the time singular limit when the ratio between
+inertial and damping effects tends to zero.",1404.6342v1
+2014-05-12,A note on a strongly damped wave equation with fast growing nonlinearities,"A strongly damped wave equation including the displacement depending
+nonlinear damping term and nonlinear interaction function is considered. The
+main aim of the note is to show that under the standard dissipativity
+restrictions on the nonlinearities involved the initial boundary value problem
+for the considered equation is globally well-posed in the class of sufficiently
+regular solutions and the semigroup generated by the problem possesses a global
+attractor in the corresponding phase space. These results are obtained for the
+nonlinearities of an arbitrary polynomial growth and without the assumption
+that the considered problem has a global Lyapunov function.",1405.2707v1
+2014-06-03,Optimal Estimation of a Classical Force with a Damped Oscillator in the non-Markovian Bath,"We solve the optimal quantum limit of probing a classical force exactly by a
+damped oscillator initially prepared in the factorized squeezed state. The
+memory effects of the thermal bath on the oscillator evolution are
+investigated. We show that the optimal force sensitivity obtained by the
+quantum estimation theory approaches to zero for the non-Markovian bath,
+whereas approaches to a finite non-zero value for the Markovian bath as the
+energy of the damped oscillator goes to infinity.",1406.0658v1
+2014-08-11,Characterization and suppression techniques for degree of radiation damping in inversion recovery measurements,"Radiation damping (RD) has been shown to affect T1 measurement in inversion
+recovery experiments. In this work, we demonstrate that the extent of RD
+depends upon the T1 of the sample. RD difference spectroscopy (RADDSY) is used
+to characterize the severity of RD, while gradient inversion recovery (GIR) is
+used for RD suppression in T1 measurements. At 9.4 T, for the radiation damping
+characteristic time (Trd) of 50 ms, these investigations show non-negligible RD
+effects for T1 values greater than Trd, with severe distortions for T1 longer
+than about 150 ms, showing reasonable agreement with the predicted Trd. We also
+report a discrepancy between published expressions for the characteristic RD
+time.",1408.2457v2
+2014-09-28,Spin-electron acoustic waves: The Landau damping and ion contribution in the spectrum,"Separated spin-up and spin-down quantum kinetics is derived for more detailed
+research of the spin-electron acoustic waves. Kinetic theory allows to obtain
+spectrum of the spin-electron acoustic waves including effects of occupation of
+quantum states more accurately than quantum hydrodynamics. We apply quantum
+kinetic to calculate the Landau damping of the spin-electron acoustic waves. We
+have considered contribution of ions dynamics in the spin-electron acoustic
+wave spectrum. We obtain contribution of ions in the Landau damping in
+temperature regime of classic ions. Kinetic analysis for ion-acoustic, zero
+sound, and Langmuir waves at separated spin-up and spin-down electron dynamics
+is presented as well.",1409.7885v1
+2014-10-05,Ultimate limit of field confinement by surface plasmon polaritons,"We show that electric field confinement in surface plasmon polaritons
+propagating at the metal/dielectric interfaces enhances the loss due to Landau
+damping and which effectively limits the degree of confinement itself. We prove
+that Landau damping and associated with it surface collision damping follow
+directly from Lindhard formula for the dielectric constant of free electron gas
+Furthermore, we demonstrate that even if all the conventional loss mechanisms,
+caused by phonons, electron-electron, and interface roughness scattering, were
+eliminated, the maximum attainable degree of confinement and the loss
+accompanying it would not change significantly compared to the best existing
+plasmonic materials, such as silver.",1410.1226v1
+2014-10-15,Quasiparticle Damping of Surface Waves in Superfluid $^3$He and $^4$He,"Oscillations on free surface of superfluids at the inviscid limit are damped
+by quasiparticle scattering. We have studied this effect in both superfluids
+$^3$He and $^4$He deep below the respective critical temperatures. Surface
+oscillators offer several benefits over immersed mechanical oscillators
+traditionally used for similar purposes. Damping is modeled as specular
+scattering of ballistic quasiparticles from the moving free surface. The model
+is in reasonable agreement with our measurements for superfluid $^4$He but
+significant deviation is found for $^3$He.",1410.4071v1
+2014-12-22,Long time behavior for a semilinear hyperbolic equation with asymtotically vanishing damping term and convex potential,"We investigate the asymptotic behavior, as t goes to infinity, for a
+semilinear hyperbolic equation with asymptotically smal dissipation and convex
+potential. We prove that if the damping term behaves like K/t^\alpha for t
+large enough, k>0 and 0</alpha<1 then every global solution converges weakly to
+an equilibrium point. This result is a positive answer to a question left open
+in the paper [A. Cabot and P. Frankel, Asymptotics for some semilinear
+hyperbolic equation with non-autonomous damping. J. Differential Equations 252
+(2012) 294-322.]",1412.7008v1
+2015-03-14,Stabilization of the nonlinear damped wave equation via linear weak observability,"We consider the problem of energy decay rates for nonlinearly damped abstract
+infinite dimensional systems. We prove sharp, simple and quasi-optimal energy
+decay rates through an indirect method, namely a weak observability estimate
+for the corresponding undamped system. One of the main advantage of these
+results is that they allow to combine the optimal-weight convexity method of
+Alabau-Boussouira and a methodology of Ammari-Tucsnak for weak stabilization by
+observability. Our results extend to nonlinearly damped systems, those of
+Ammari and Tucsnak. At the end, we give an appendix on the weak stabilization
+of linear evolution systems.",1503.04356v1
+2015-06-02,"On the the wave equation with hyperbolic dynamical boundary conditions, interior and boundary damping and source","The aim of the paper is to study local Hadamard well-posedness for wave
+equation with an hyperbolic dynamical boundary condition, internal and/or
+boundary damping and sources for initial data in the natural energy space.
+Moreover the regularity of solutions is studied. Finally a dynamical system is
+generated when sources are at most linear at infinity, or they are dominated by
+the damping terms.",1506.00910v4
+2015-06-15,Tautochrone in the damped cycloidal pendulum,"The tautochrone on a cycloid curve is usually considered without drag force.
+In this work, we investigate the motion of a damped cycloidal pendulum under
+presence of a drag force. Using the Lagrange formulation, and considering
+linear dependence with velocity for damping force, we found the dynamics of the
+system to remain tautochrone. This dictates the possibility for studying the
+tautochrone experimentally, e.g. the cycloidal pendulum in water or oil.",1506.04943v2
+2015-10-01,Impact of surface collisions on enhancement and quenching of the luminescence near the metal nanoparticles,"The fact that surface-induced damping rate of surface plasmon polaritons
+(SPPs) in metal nanoparticles increases with the decrease of particle size is
+well known. We show that this rate also increases with the degree of the mode
+confinement, hence damping of the higher order nonradiative SPP modes in
+spherical particles is greatly enhanced relative to damping of the fundamental
+(dipole) SPP mode. Since higher order modes are the ones responsible for
+quenching of luminescence in the vicinity of metal surfaces, the degree of
+quenching increases resulting in a substantial decrease in the amount of
+attainable enhancement of the luminescence",1510.00321v1
+2015-10-22,On numerical Landau damping for splitting methods applied to the Vlasov-HMF model,"We consider time discretizations of the Vlasov-HMF (Hamiltonian Mean-Field)
+equation based on splitting methods between the linear and non-linear parts. We
+consider solutions starting in a small Sobolev neighborhood of a spatially
+homogeneous state satisfying a linearized stability criterion (Penrose
+criterion). We prove that the numerical solutions exhibit a scattering behavior
+to a modified state, which implies a nonlinear Landau damping effect with
+polynomial rate of damping. Moreover, we prove that the modified state is close
+to the continuous one and provide error estimates with respect to the time
+stepsize.",1510.06555v1
+2015-11-02,Asymptotic decomposition for nonlinear damped Klein-Gordon equations,"In this paper, we proved that if the solution to damped focusing Klein-Gordon
+equations is global forward in time, then it will decouple into a finite number
+of equilibrium points with different shifts from the origin. The core
+ingredient of our proof is the existence of the ""concentration-compact
+attractor"" which yields a finite number of profiles. Using damping effect, we
+can prove all the profiles are equilibrium points.",1511.00437v3
+2015-11-11,Contact Stiffness and Damping of Liquid Films in Dynamic Atomic Force Microscopy,"Small-amplitude dynamic atomic force microscopy (dynamic-AFM) in a simple
+nonpolar liquid was studied through molecular dynamics simulations. We find
+that within linear dynamics regime, the contact stiffness and damping of the
+confined film exhibit the similar solvation force oscillations, and they are
+generally out-of-phase. For the solidified film with integer monolayer
+thickness, further compression of the film before layering transition leads to
+higher stiffness and lower damping. We find that molecular diffusion in the
+solidified film was nevertheless enhanced due to the mechanical excitation of
+AFM tip.",1511.03580v1
+2015-11-13,Nonlinear Radiation Damping of Nuclear Spin Waves and Magnetoelastic Waves in Antiferromagnets,"Parallel pumping of nuclear spin waves in antiferromagnetic CsMnF3 at liquid
+helium temperatures and magnetoelastic waves in antiferromagnetic FeBO3 at
+liquid nitrogen temperature in a helical resonator was studied. It was found
+that the absorbed microwave power is approximately equal to the irradiated
+power from the sample and that the main restriction mechanism of absortption in
+both cases is defined by the nonlinear radiation damping predicted about two
+decades ago. We believe that the nonlinear radiation damping is a common
+feature of parallel pumping technique of all normal magnetic excitations and it
+can be detected by purposeful experiments.",1511.04396v1
+2016-03-01,Damped vacuum states of light,"We consider one-dimensional propagation of quantum light in the presence of a
+block of material, with a full account of dispersion and absorption. The
+electromagnetic zero-point energy for some frequencies is damped (suppressed)
+by the block below the free-space value, while for other frequencies it is
+increased. We also calculate the regularized (Casimir) zero-point energy at
+each frequency and find that it too is damped below the free-space value (zero)
+for some frequencies. The total Casimir energy is positive.",1603.00233v2
+2016-04-18,Parameter Estimation of Gaussian-Damped Sinusoids from a Geometric Perspective,"The five parameter gaussian damped sinusoid equation is a reasonable model
+for betatron motion with chromatic decoherence of the proton bunch centroid
+signal in the ring at the Spallation Neutron Source. A geometric method for
+efficiently fitting this equation to the turn by turn signals to extract the
+betatron tune and damping constant will be presented. This method separates the
+parameters into global and local parameters and allows the use of vector
+arithmetic to eliminate the local parameters from the parameter search space.
+Furthermore, this method is easily generalized to reduce the parameter search
+space for a larger class of problems.",1604.05167v1
+2016-04-20,Landau damping in finite regularity for unconfined systems with screened interactions,"We prove Landau damping for the collisionless Vlasov equation with a class of
+$L^1$ interaction potentials (including the physical case of screened Coulomb
+interactions) on $\mathbb R^3_x \times \mathbb R^3_v$ for localized
+disturbances of an infinite, homogeneous background. Unlike the confined case
+$\mathbb T^3_x \times \mathbb R_v^3$, results are obtained for initial data in
+Sobolev spaces (as well as Gevrey and analytic classes). For spatial
+frequencies bounded away from zero, the Landau damping of the density is
+similar to the confined case. The finite regularity is possible due to an
+additional dispersive mechanism available on $\mathbb R_x^3$ which reduces the
+strength of the plasma echo resonance.",1604.05783v1
+2016-04-26,Trigonometric Splines for Oscillator Simulation,"We investigate the effects of numerical damping for oscillator simulation
+with spline methods. Numerical damping results in an artificial loss of energy
+and leads therefore to unreliable results in the simulation of autonomous
+systems, as e.g.\ oscillators. We show that the negative effects of numerical
+damping can be eliminated by the use of trigonometric splines. This will be in
+particular important for spline based adaptive methods.",1604.07607v1
+2016-07-13,Optimal decay rate for the wave equation on a square with constant damping on a strip,"We consider the damped wave equation with Dirichlet boundary conditions on
+the unit square. We assume the damping to be a characteristic function of a
+strip. We prove the exact $t^{-4/3}$-decay rate for the energy of classical
+solutions. This answers a question of Anantharaman and L\'eautaud (2014).",1607.03633v2
+2016-08-29,"Stochastic 3D Navier-Stokes equations with nonlinear damping: martingale solution, strong solution and small time large deviation principles","In this paper, by using classical Faedo-Galerkin approximation and
+compactness method, the existence of martingale solutions for the stochastic 3D
+Navier-Stokes equations with nonlinear damping is obtained. The existence and
+uniqueness of strong solution are proved for $\beta > 3$ with any $\alpha>0$
+and $\alpha \geq \frac12$ as $\beta = 3$. Meanwhile, a small time large
+deviation principle for the stochastic 3D Navier-Stokes equation with damping
+is proved for $\beta > 3$ with any $\alpha>0$ and $\alpha \geq \frac12$ as
+$\beta = 3$.",1608.07996v1
+2016-09-05,Estimates of lifespan and blow-up rates for the wave equation with a time-dependent damping and a power-type nonlinearity,"We study blow-up behavior of solutions for the Cauchy problem of the
+semilinear wave equation with time-dependent damping. When the damping is
+effective, and the nonlinearity is subcritical, we show the blow-up rates and
+the sharp lifespan estimates of solutions. Upper estimates are proved by an ODE
+argument, and lower estimates are given by a method of scaling variables.",1609.01035v2
+2016-09-06,Numerical Convergence Rate for a Diffusive Limit of Hyperbolic Systems: p-System with Damping,"This paper deals with diffusive limit of the p-system with damping and its
+approximation by an Asymptotic Preserving (AP) Finite Volume scheme. Provided
+the system is endowed with an entropy-entropy flux pair, we give the
+convergence rate of classical solutions of the p-system with damping towards
+the smooth solutions of the porous media equation using a relative entropy
+method. Adopting a semi-discrete scheme, we establish that the convergence rate
+is preserved by the approximated solutions. Several numerical experiments
+illustrate the relevance of this result.",1609.01436v1
+2016-09-20,Global existence and asymptotic behavior of solutions to the Euler equations with time-dependent damping,"We study the isentropic Euler equations with time-dependent damping, given by
+$\frac{\mu}{(1+t)^\lambda}\rho u$. Here, $\lambda,\mu$ are two non-negative
+constants to describe the decay rate of damping with respect to time. We will
+investigate the global existence and asymptotic behavior of small data
+solutions to the Euler equations when $0<\lambda<1,0<\mu$ in multi-dimensions
+$n\geq 1$. The asymptotic behavior will coincide with the one that obtained by
+many authors in the case $\lambda=0$. We will also show that the solution can
+only decay polynomially in time while in the three dimensions, the vorticity
+will decay exponentially fast.",1609.06286v1
+2016-11-08,Emulated Inertia and Damping of Converter-Interfaced Power Source,"Converter-interfaced power sources (CIPSs), like wind turbine and energy
+storage, can be switched to the inertia emulation mode when the detected
+frequency deviation exceeds a pre-designed threshold, i.e. dead band, to
+support the frequency response of a power grid. This letter proposes an
+approach to derive the emulated inertia and damping from a CIPS based on the
+linearized model of the CIPS and the power grid, where the grid is represented
+by an equivalent single machine. The emulated inertia and damping can be
+explicitly expressed in time and turn out to be time-dependent.",1611.02698v1
+2016-12-09,Ornstein-Uhlenbeck Process with Fluctuating Damping,"This paper studies Langevin equation with random damping due to
+multiplicative noise and its solution. Two types of multiplicative noise,
+namely the dichotomous noise and fractional Gaussian noise are considered.
+Their solutions are obtained explicitly, with the expressions of the mean and
+covariance determined explicitly. Properties of the mean and covariance of the
+Ornstein-Uhlenbeck process with random damping, in particular the asymptotic
+behavior, are studied. The effect of the multiplicative noise on the stability
+property of the resulting processes is investigated.",1612.03013v3
+2016-12-20,Symmetry group classification and optimal reduction of a class of damped Timoshenko beam system with a nonlinear rotational moment,"We consider a nonlinear Timoshenko system of partial differential equations
+(PDEs) with a frictional damping term in rotation angle. The nonlinearity is
+due to the arbitrary dependence on the rotation moment. A Lie symmetry group
+classification of the arbitrary function of rotation moment is presented. An
+optimal system of one-dimensional subalgebras of the nonlinear damped
+Timoshenko system is derived for all the non-linear cases. All possible
+invariant variables of the optimal systems for the three non-linear cases are
+presented. The corresponding reduced systems of ordinary differential equations
+(ODEs) are also provided.",1612.06775v1
+2017-03-14,Landau damping in the multiscale Vlasov theory,"Vlasov kinetic theory is extended by adopting an extra one particle
+distribution function as an additional state variable characterizing the
+micro-turbulence internal structure. The extended Vlasov equation keeps the
+reversibility, the Hamiltonian structure, and the entropy conservation of the
+original Vlasov equation. In the setting of the extended Vlasov theory we then
+argue that the Fokker-Planck type damping in the velocity dependence of the
+extra distribution function induces the Landau damping. The same type of
+extension is made also in the setting of fluid mechanics.",1703.04577v2
+2017-03-15,Energy decay and diffusion phenomenon for the asymptotically periodic damped wave equation,"We prove local and global energy decay for the asymptotically periodic damped
+wave equation on the Euclidean space. Since the behavior of high frequencies is
+already mostly understood, this paper is mainly about the contribution of low
+frequencies. We show in particular that the damped wave behaves like a solution
+of a heat equation which depends on the H-limit of the metric and the mean
+value of the absorption index.",1703.05112v1
+2017-04-03,Linear inviscid damping and vorticity depletion for shear flows,"In this paper, we prove the linear damping for the 2-D Euler equations around
+a class of shear flows under the assumption that the linearized operator has no
+embedding eigenvalues. For the symmetric flows, we obtain the explicit decay
+estimates of the velocity, which is the same as one for monotone shear flows.
+We confirm a new dynamical phenomena found by Bouchet and Morita: the depletion
+of the vorticity at the stationary streamlines, which could be viewed as a new
+mechanism leading to the damping for the base flows with stationary
+streamlines.",1704.00428v1
+2017-04-25,Diffusion phenomena for the wave equation with space-dependent damping term growing at infinity,"In this paper, we study the asymptotic behavior of solutions to the wave
+equation with damping depending on the space variable and growing at the
+spatial infinity. We prove that the solution is approximated by that of the
+corresponding heat equation as time tends to infinity. The proof is based on
+semigroup estimates for the corresponding heat equation and weighted energy
+estimates for the damped wave equation. To construct a suitable weight function
+for the energy estimates, we study a certain elliptic problem.",1704.07650v1
+2017-06-05,Mixed finite elements for global tide models with nonlinear damping,"We study mixed finite element methods for the rotating shallow water
+equations with linearized momentum terms but nonlinear drag. By means of an
+equivalent second-order formulation, we prove long-time stability of the system
+without energy accumulation. We also give rates of damping in unforced systems
+and various continuous dependence results on initial conditions and forcing
+terms. \emph{A priori} error estimates for the momentum and free surface
+elevation are given in $L^2$ as well as for the time derivative and divergence
+of the momentum. Numerical results confirm the theoretical results regarding
+both energy damping and convergence rates.",1706.01352v1
+2017-07-11,Stability of partially locked states in the Kuramoto model through Landau damping with Sobolev regularity,"The Kuramoto model is a mean-field model for the synchronisation behaviour of
+oscillators, which exhibits Landau damping. In a recent work, the nonlinear
+stability of a class of spatially inhomogeneous stationary states was shown
+under the assumption of analytic regularity. This paper proves the nonlinear
+Landau damping under the assumption of Sobolev regularity. The weaker
+regularity required the construction of a different more robust bootstrap
+argument, which focuses on the nonlinear Volterra equation of the order
+parameter.",1707.03475v2
+2017-08-27,Global well-posedness for the semilinear wave equation with time dependent damping in the overdamping case,"We study global existence of solutions to the Cauchy problem for the wave
+equation with time-dependent damping and a power nonlinearity in the
+overdamping case. We prove the global well-posedness for small data in the
+energy space for the whole energy-subcritical case. This result implies that
+small data blow-up does not occur in the overdamping case, different from the
+other cases, i.e. effective or non-effective damping.",1708.08044v2
+2017-09-04,A note on the blowup of scale invariant damping wave equation with sub-Strauss exponent,"We concern the blow up problem to the scale invariant damping wave equations
+with sub-Strauss exponent. This problem has been studied by Lai, Takamura and
+Wakasa (\cite{Lai17}) and Ikeda and Sobajima \cite{Ikedapre} recently. In
+present paper, we extend the blowup exponent from $p_F(n)\leq p<p_S(n+2\mu)$ to
+$1<p<p_S(n+\mu)$ without small restriction on $\mu$. Moreover, the upper bound
+of lifespan is derived with uniform estimate $T(\varepsilon)\leq
+C\varepsilon^{-2p(p-1)/\gamma(p,n+2\mu)}$. This result extends the blowup
+result of semilinear wave equation and shows the wave-like behavior of scale
+invariant damping wave equation's solution even with large $\mu>1$.",1709.00866v2
+2017-09-24,Suppression of Recurrence in the Hermite-Spectral Method for Transport Equations,"We study the unphysical recurrence phenomenon arising in the numerical
+simulation of the transport equations using Hermite-spectral method. From a
+mathematical point of view, the suppression of this numerical artifact with
+filters is theoretically analyzed for two types of transport equations. It is
+rigorously proven that all the non-constant modes are damped exponentially by
+the filters in both models, and formally shown that the filter does not affect
+the damping rate of the electric energy in the linear Landau damping problem.
+Numerical tests are performed to show the effect of the filters.",1709.08194v1
+2017-11-01,Life-Span of Semilinear Wave Equations with Scale-invariant Damping: Critical Strauss Exponent Case,"The blow up problem of the semilinear scale-invariant damping wave equation
+with critical Strauss type exponent is investigated. The life span is shown to
+be: $T(\varepsilon)\leq C\exp(\varepsilon^{-2p(p-1)})$ when $p=p_S(n+\mu)$ for
+$0<\mu<\frac{n^2+n+2}{n+2}$. This result completes our previous study
+\cite{Tu-Lin} on the sub-Strauss type exponent $p<p_S(n+\mu)$. Our novelty is
+to construct the suitable test function from the modified Bessel function. This
+approach might be also applied to the other type damping wave equations.",1711.00223v1
+2017-11-14,Spin-Noise and Damping in Individual Metallic Ferromagnetic Nanoparticles,"We introduce a highly sensitive and relatively simple technique to observe
+magnetization motion in single Ni nanoparticles, based on charge sensing by
+electron tunneling at millikelvin temperature. Sequential electron tunneling
+via the nanoparticle drives nonequilibrium magnetization dynamics, which
+induces an effective charge noise that we measure in real time. In the free
+spin diffusion regime, where the electrons and magnetization are in detailed
+balance, we observe that magnetic damping time exhibits a peak with the
+magnetic field, with a record long damping time of $\simeq 10$~ms.",1711.05142v1
+2017-12-04,Graviton-mediated dark matter model explanation the DAMPE electron excess and search at $e^+e^-$ colliders,"The very recent result of the DAMPE cosmic ray spectrum of electrons shows a
+narrow bump above the background at around 1.4 TeV. We attempt to explain the
+DAMPE electron excess in a simplified Kaluza-Klein graviton-mediated dark
+matter model, in which the graviton only interacts with leptons and dark
+matter. The related phenomenological discussions are given and this simplified
+graviton-mediated dark matter model has the potential to be cross-tested in
+future lepton collider experiments.",1712.01143v1
+2017-12-13,On nonlinear damped wave equations for positive operators. I. Discrete spectrum,"In this paper we study a Cauchy problem for the nonlinear damped wave
+equations for a general positive operator with discrete spectrum. We derive the
+exponential in time decay of solutions to the linear problem with decay rate
+depending on the interplay between the bottom of the operator's spectrum and
+the mass term. Consequently, we prove global in time well-posedness results for
+semilinear and for more general nonlinear equations with small data. Examples
+are given for nonlinear damped wave equations for the harmonic oscillator, for
+the twisted Laplacian (Landau Hamiltonian), and for the Laplacians on compact
+manifolds.",1712.05009v1
+2018-03-14,Damped Newton's Method on Riemannian Manifolds,"A damped Newton's method to find a singularity of a vector field in
+Riemannian setting is presented with global convergence study. It is ensured
+that the sequence generated by the proposed method reduces to a sequence
+generated by the Riemannian version of the classical Newton's method after a
+finite number of iterations, consequently its convergence rate is
+superlinear/quadratic. Moreover, numerical experiments illustrate that the
+damped Newton's method has better performance than Newton's method in number of
+iteration and computational time.",1803.05126v2
+2018-05-29,Asymptotic profile of solutions for strongly damped Klein-Gordon equations,"We consider the Cauchy problem in the whole space for strongly damped
+Klein-Gordon equations. We derive asymptotic profles of solutions with weighted
+initial data by a simple method introduced by R. Ikehata. The obtained results
+show that the wave effect will be weak because of the mass term, especially in
+the low dimensional case (n = 1,2) as compared with the strongly damped wave
+equations without mass term (m = 0), so the most interesting topic in this
+paper is the n = 1,2 cases.",1805.11975v1
+2018-06-18,Damped second order flow applied to image denoising,"In this paper, we introduce a new image denoising model: the damped flow
+(DF), which is a second order nonlinear evolution equation associated with a
+class of energy functionals of image. The existence, uniqueness and
+regularization property of DF are proven. For the numerical implementation,
+based on the St\""{o}rmer-Verlet method, a discrete damped flow, SV-DDF, is
+developed. The convergence of SV-DDF is studied as well. Several numerical
+experiments, as well as a comparison with other methods, are provided to
+demonstrate the feasibility and effectiveness of the SV-DDF.",1806.06732v2
+2018-07-10,Cyclotron Damping along an Uniform Magnetic Field,"We prove cyclotron damping for the collisionless Vlasov-Maxwell equations on
+$\mathbb{T}_{x}^{3}\times\mathbb{R}_{v}^{3}$ under the assumptions that the
+electric induction is zero and $(\mathcal{\mathbf{PSC}})$ holds. It is a
+crucial step to solve the stability problem of the Vlasov-Maxwell equations.
+Our proof is based on a new dynamical system of the plasma particles,
+originating from Faraday Law of Electromagnetic induction and Lenz's Law. On
+the basis of it, we use the improved Newton iteration scheme to show the
+damping mechanism.",1807.05254v3
+2018-08-22,Radiation Damping of a Yang-Mills Particle Revisited,"The problem of a color-charged point particle interacting with a four
+dimensional Yang-Mills gauge theory is revisited. The radiation damping is
+obtained inspired in the Dirac's computation. The difficulties in the
+non-abelian case were solved by using an ansatz for the Li\'enard-Wiechert
+potentials, already used in the literature for finding solutions to the
+Yang-Mills equations. Three non-trivial examples of radiation damping for the
+non-abelian particle are discussed in detail.",1808.07533v2
+2018-08-28,Enhancement of zonal flow damping due to resonant magnetic perturbations in the background of an equilibrium $E \times B$ sheared flow,"Using a parametric interaction formalism, we show that the equilibrium
+sheared rotation can enhance the zonal flow damping effect found in Ref. [M.
+Leconte and P.H. Diamond, \emph{Phys. Plasmas} 19, 055903 (2012)]. This
+additional damping contribution is proportional to $(L_s/L_V)^2 \times \delta
+B_r^2 / B^2$, where $L_s/L_V$ is the ratio of magnetic shear length to the
+scale-length of equilibrium $E \times B$ flow shear, and $\delta B_r / B$ is
+the amplitude of the external magnetic perturbation normalized to the
+background magnetic field.",1808.09110v1
+2018-08-30,Optimal indirect stability of a weakly damped elastic abstract system of second order equations coupled by velocities,"In this paper, by means of the Riesz basis approach, we study the stability
+of a weakly damped system of two second order evolution equations coupled
+through the velocities. If the fractional order damping becomes viscous and the
+waves propagate with equal speeds, we prove exponential stability of the system
+and, otherwise, we establish an optimal polynomial decay rate. Finally, we
+provide some illustrative examples.",1808.10256v1
+2018-09-10,Linear inviscid damping for the $β$-plane equation,"In this paper, we study the linear inviscid damping for the linearized
+$\beta$-plane equation around shear flows. We develop a new method to give the
+explicit decay rate of the velocity for a class of monotone shear flows. This
+method is based on the space-time estimate and the vector field method in sprit
+of the wave equation. For general shear flows including the Sinus flow, we also
+prove the linear damping by establishing the limiting absorption principle,
+which is based on the compactness method introduced by Wei-Zhang-Zhao in
+\cite{WZZ2}. The main difficulty is that the Rayleigh-Kuo equation has more
+singular points due to the Coriolis effects so that the compactness argument
+becomes more involved and delicate.",1809.03065v1
+2018-10-23,Perfect absorption of water waves by linear or nonlinear critical coupling,"We report on experiments of perfect absorption for surface gravity waves
+impinging a wall structured by a subwavelength resonator. By tuning the
+geometry of the resonator, a balance is achieved between the radiation damping
+and the intrinsic viscous damping, resulting in perfect absorption by critical
+coupling. Besides, it is shown that the resistance of the resonator, hence the
+intrinsic damping, can be controlled by the wave amplitude, which provides a
+way for perfect absorption tuned by nonlinear mechanisms. The perfect absorber
+that we propose, without moving parts or added material, is simple, robust and
+it presents a deeply subwavelength ratio wavelength/size $\simeq 18$.",1810.09884v1
+2018-12-16,Damping of sound waves by bulk viscosity in reacting gases,"The very long standing problem of sound waves propagation in fluids is
+reexamined. In particular, from the analysis of the wave damping in reacting
+gases following the work of Einsten \citep{Ein}, it is found that the damping
+due to the chemical reactions occurs nonetheless the second (bulk) viscosity
+introduced by Landau \& Lifshitz \citep{LL86} is zero. The simple but important
+case of a recombining Hydrogen plasma is examined.",1812.06478v1
+2019-02-27,Forward Discretely Self-Similar Solutions of the MHD Equations and the Viscoelastic Navier-Stokes Equations with Damping,"In this paper, we prove the existence of forward discretely self-similar
+solutions to the MHD equations and the viscoelastic Navier-Stokes equations
+with damping with large weak $L^3$ initial data. The same proving techniques
+are also applied to construct self-similar solutions to the MHD equations and
+the viscoelastic Navier-Stokes equations with damping with large weak $L^3$
+initial data. This approach is based on [Z. Bradshaw and T.-P. Tsai, Ann. Henri
+Poincar'{e}, vol. 18, no. 3, 1095-1119, 2017].",1902.10771v3
+2019-03-11,The effect of magnetic twist on resonant absorption of slow sausage waves in magnetic flux tubes,"Observations show that twisted magnetic flux tubes are present throughout the
+sun's atmosphere. The main aim of this work is to obtain the damping rate of
+sausage modes in the presence of magnetic twist. Using the connection formulae
+obtained by Sakurai et al. (1991), we investigate resonant absorption of the
+sausage modes in the slow continuum under photosphere conditions. We derive the
+dispersion relation and solve it numerically and consequently obtain the
+frequencies and damping rates of the slow surface sausage modes. We conclude
+that the magnetic twist can result in strong damping in comparison with the
+untwisted case.",1903.04171v1
+2019-03-14,Endpoint Strichartz estimate for the damped wave equation and its application,"Recently, the Strichartz estimates for the damped wave equation was obtained
+by the first author except for the wave endpoint case. In the present paper, we
+give the Strichartz estimate in the wave endpoint case. We slightly modify the
+argument of Keel--Tao. Moreover, we apply the endpoint Strichartz estimate to
+the unconditional uniqueness for the energy critical nonlinear damped wave
+equation. This problem seems not to be solvable as the perturbation of the wave
+equation.",1903.05891v2
+2019-04-02,Linear inviscid damping in Gevrey spaces,"We prove linear inviscid damping near a general class of monotone shear flows
+in a finite channel, in Gevrey spaces. It is an essential step towards proving
+nonlinear inviscid damping for general shear flows that are not close to the
+Couette flow, which is a major open problem in 2d Euler equations.",1904.01188v2
+2019-04-16,Damping modes of harmonic oscillator in open quantum systems,"Through a set of generators that preserves the hermiticity and trace of
+density matrices, we analyze the damping of harmonic oscillator in open quantum
+systems into four modes, distinguished by their specific effects on the
+covariance matrix of position and momentum of the oscillator. The damping modes
+could either cause exponential decay to the initial covariance matrix or shift
+its components. They have to act together properly in actual dynamics to ensure
+that the generalized uncertainty relation is satisfied. We use a few quantum
+master equations to illustrate the results.",1904.07452v2
+2019-05-20,Stabilization of two strongly coupled hyperbolic equations in exterior domains,"In this paper we study the behavior of the total energy and the $L^2$-norm of
+solutions of two coupled hyperbolic equations by velocities in exterior
+domains. Only one of the two equations is directly damped by a localized
+damping term. We show that, when the damping set contains the coupling one and
+the coupling term is effective at infinity and on captive region, then the
+total energy decays uniformly and the $L^2$-norm of smooth solutions is
+bounded. In the case of two Klein-Gordon equations with equal speeds we deduce
+an exponential decay of the energy.",1905.08370v1
+2019-06-02,Mixed control of vibrational systems,"We consider new performance measures for vibrational systems based on the
+$H_2$ norm of linear time invariant systems. New measures will be used as an
+optimization criterion for the optimal damping of vibrational systems. We
+consider both theoretical and concrete cases in order to show how new measures
+stack up against the standard measures. The quality and advantages of new
+measures as well as the behaviour of optimal damping positions and
+corresponding damping viscosities are illustrated in numerical experiments.",1906.00503v1
+2019-06-27,Comments on the linear modified Poisson-Boltzmann equation in electrolyte solution theory,"Three analytic results are proposed for a linear form of the modified
+Poisson-Boltzmann equation in the theory of bulk electrolytes. Comparison is
+also made with the mean spherical approximation results. The linear theories
+predict a transition of the mean electrostatic potential from a
+Debye-H\""{u}ckel type damped exponential to a damped oscillatory behaviour as
+the electrolyte concentration increases beyond a critical value. The screening
+length decreases with increasing concentration when the mean electrostatic
+potential is damped oscillatory. A comparison is made with one set of recent
+experimental screening results for aqueous NaCl electrolytes.",1906.11584v1
+2019-09-19,Growth rate and gain of stimulated Brillouin scattering considering nonlinear Landau damping due to particle trapping,"Growth rate and gain of SBS considering the reduced Landau damping due to
+particle trapping has been proposed to predict the growth and average level of
+SBS reflectivity. Due to particle trapping, the reduced Landau damping has been
+taken used of to calculate the gain of SBS, which will make the simulation data
+of SBS average reflectivity be consistent to the Tang model better. This work
+will solve the pending questions in laser-plasma interaction and have wide
+applications in parametric instabilities.",1909.11606v1
+2019-11-26,Pullback Attractors for a Critical Degenerate Wave Equation with Time-dependent Damping,"The aim of this paper is to analyze the long-time dynamical behavior of the
+solution for a degenerate wave equation with time-dependent damping term
+$\partial_{tt}u + \beta(t)\partial_tu = \mathcal{L}u(x,t) + f(u)$ on a bounded
+domain $\Omega\subset\mathbb{R}^N$ with Dirichlet boundary conditions. Under
+some restrictions on $\beta(t)$ and critical growth restrictions on the
+nonlinear term $f$, we will prove the local and global well-posedness of the
+solution and derive the existence of a pullback attractor for the process
+associated with the degenerate damped hyperbolic problem.",1911.11432v1
+2019-12-18,Blow-up criteria for linearly damped nonlinear Schrödinger equations,"We consider the Cauchy problem for linearly damped nonlinear Schr\""odinger
+equations
+  \[ i\partial_t u + \Delta u + i a u= \pm |u|^\alpha u, \quad (t,x) \in
+[0,\infty) \times \mathbb{R}^N, \] where $a>0$ and $\alpha>0$. We prove the
+global existence and scattering for a sufficiently large damping parameter in
+the energy-critical case. We also prove the existence of finite time blow-up
+$H^1$ solutions to the focusing problem in the mass-critical and
+mass-supercritical cases.",1912.08752v2
+2020-01-17,Bounding the Classical Capacity of Multilevel Damping Quantum Channels,"A recent method to certify the classical capacity of quantum communication
+channels is applied for general damping channels in finite dimension. The
+method compares the mutual information obtained by coding on the computational
+and a Fourier basis, which can be obtained by just two local measurement
+settings and classical optimization. The results for large representative
+classes of different damping structures are presented.",2001.06486v2
+2020-01-27,Robustness of polynomial stability of damped wave equations,"In this paper we present new results on the preservation of polynomial
+stability of damped wave equations under addition of perturbing terms. We in
+particular introduce sufficient conditions for the stability of perturbed
+two-dimensional wave equations on rectangular domains, a one-dimensional weakly
+damped Webster's equation, and a wave equation with an acoustic boundary
+condition. In the case of Webster's equation, we use our results to compute
+explicit numerical bounds that guarantee the polynomial stability of the
+perturbed equation.",2001.10033v3
+2020-02-16,Blow up results for semi-linear structural damped wave model with nonlinear memory,"This article is to study the nonexistence of global solutions to semi-linear
+structurally damped wave equation with nonlinear memory in $\R^n$ for any space
+dimensions $n\ge 1$ and for the initial arbitrarily small data being subject to
+the positivity assumption. We intend to apply the method of a modified test
+function to establish blow-up results and to overcome some difficulties as well
+caused by the well-known fractional Laplacian $(-\Delta)^{\sigma/2}$ in
+structural damping terms.",2002.06582v1
+2020-03-04,Existence and uniqueness of solutions to the damped Navier-Stokes equations with Navier boundary conditions for three dimensional incompressible fluid,"In this article, we study the solutions of the damped Navier--Stokes equation
+with Navier boundary condition in a bounded domain $\Omega$ in $\mathbb{R}^3$
+with smooth boundary. The existence of the solutions is global with the damped
+term $\vartheta |u|^{\beta-1}u, \vartheta >0.$ The regularity and uniqueness of
+solutions with Navier boundary condition is also studied. This extends the
+existing results in literature.",2003.01903v1
+2020-04-22,Logarithmic stabilization of an acoustic system with a damping term of Brinkman type,"We study the problem of stabilization for the acoustic system with a
+spatially distributed damping. Without imposing any hypotheses on the
+structural properties of the damping term, we identify logarithmic decay of
+solutions with growing time. Logarithmic decay rate is shown by using a
+frequency domain method and combines a contradiction argument with the
+multiplier technique and a new Carleman estimate to carry out a special
+analysis for the resolvent.",2004.10669v1
+2020-06-09,Lifespan of solutions to a damped fourth-order wave equation with logarithmic nonlinearity,"This paper is devoted to the lifespan of solutions to a damped fourth-order
+wave equation with logarithmic nonlinearity $$u_{tt}+\Delta^2u-\Delta
+u-\omega\Delta u_t+\alpha(t)u_t=|u|^{p-2}u\ln|u|.$$ Finite time blow-up
+criteria for solutions at both lower and high initial energy levels are
+established, and an upper bound for the blow-up time is given for each case.
+Moreover, by constructing a new auxiliary functional and making full use of the
+strong damping term, a lower bound for the blow-up time is also derived.",2006.05006v1
+2020-07-05,Oscillation of damped second order quasilinear wave equations with mixed arguments,"Following the previous work [1], we investigate the impact of damping on the
+oscillation of smooth solutions to some kind of quasilinear wave equations with
+Robin and Dirichlet boundary condition. By using generalized Riccati
+transformation and technical inequality method, we give some sufficient
+conditions to guarantee the oscillation of all smooth solutions. From the
+results, we conclude that positive damping can ``hold back"" oscillation. At
+last, some examples are presented to confirm our main results.",2007.02284v1
+2020-07-08,A competition on blow-up for semilinear wave equations with scale-invariant damping and nonlinear memory term,"In this paper, we investigate blow-up of solutions to semilinear wave
+equations with scale-invariant damping and nonlinear memory term in
+$\mathbb{R}^n$, which can be represented by the Riemann-Liouville fractional
+integral of order $1-\gamma$ with $\gamma\in(0,1)$. Our main interest is to
+study mixed influence from damping term and the memory kernel on blow-up
+conditions for the power of nonlinearity, by using test function method or
+generalized Kato's type lemma. We find a new competition, particularly for the
+small value of $\gamma$, on the blow-up range between the effective case and
+the non-effective case.",2007.03954v2
+2020-08-02,Quantum capacity analysis of multi-level amplitude damping channels,"The set of Multi-level Amplitude Damping (MAD) quantum channels is introduced
+as a generalization of the standard qubit Amplitude Damping Channel to quantum
+systems of finite dimension $d$. In the special case of $d=3$, by exploiting
+degradability, data-processing inequalities, and channel isomorphism, we
+compute the associated quantum and private classical capacities for a rather
+wide class of maps, extending the set of solvable models known so far. We
+proceed then to the evaluation of the entanglement assisted, quantum and
+classical, capacities.",2008.00477v3
+2020-08-17,Asymptotic profiles and singular limits for the viscoelastic damped wave equation with memory of type I,"In this paper, we are interested in the Cauchy problem for the viscoelastic
+damped wave equation with memory of type I. By applying WKB analysis and
+Fourier analysis, we explain the memory's influence on dissipative structures
+and asymptotic profiles of solutions to the model with weighted $L^1$ initial
+data. Furthermore, concerning standard energy and the solution itself, we
+establish singular limit relations between the Moore-Gibson-Thompson equation
+with memory and the viscoelastic damped wave equation with memory.",2008.07151v1
+2020-09-11,Asymptotic profiles for a wave equation with parameter dependent logarithmic damping,"We study a nonlocal wave equation with logarithmic damping which is rather
+weak in the low frequency zone as compared with frequently studied strong
+damping case. We consider the Cauchy problem for this model in the whole space
+and we study the asymptotic profile and optimal estimates of the solutions and
+the total energy as time goes to infinity in L^{2}-sense. In that case some
+results on hypergeometric functions are useful.",2009.06395v1
+2020-09-17,Sensitivity of steady states in a degenerately-damped stochastic Lorenz system,"We study stability of solutions for a randomly driven and degenerately damped
+version of the Lorenz '63 model. Specifically, we prove that when damping is
+absent in one of the temperature components, the system possesses a unique
+invariant probability measure if and only if noise acts on the convection
+variable. On the other hand, if there is a positive growth term on the vertical
+temperature profile, we prove that there is no normalizable invariant state.
+Our approach relies on the derivation and analysis of non-trivial Lyapunov
+functions which ensure positive recurrence or null-recurrence/transience of the
+dynamics.",2009.08429v1
+2021-02-20,Lifespan estimates for semilinear wave equations with space dependent damping and potential,"In this work, we investigate the influence of general damping and potential
+terms on the blow-up and lifespan estimates for energy solutions to power-type
+semilinear wave equations. The space-dependent damping and potential functions
+are assumed to be critical or short range, spherically symmetric perturbation.
+The blow up results and the upper bound of lifespan estimates are obtained by
+the so-called test function method. The key ingredient is to construct special
+positive solutions to the linear dual problem with the desired asymptotic
+behavior, which is reduced, in turn, to constructing solutions to certain
+elliptic ""eigenvalue"" problems.",2102.10257v1
+2021-02-24,Attractors for locally damped Bresse systems and a unique continuation property,"This paper is devoted to Bresse systems, a robust model for circular beams,
+given by a set of three coupled wave equations. The main objective is to
+establish the existence of global attractors for dynamics of semilinear
+problems with localized damping. In order to deal with localized damping a
+unique continuation property (UCP) is needed. Therefore we also provide a
+suitable UCP for Bresse systems. Our strategy is to set the problem in a
+Riemannian geometry framework and see the system as a single equation with
+different Riemann metrics. Then we perform Carleman-type estimates to get our
+result.",2102.12025v1
+2021-03-09,Global weak solution of 3D-NSE with exponential damping,"In this paper we prove the global existence of incompressible Navier-Stokes
+equations with damping $\alpha (e^{\beta |u|^2}-1)u$, where we use Friedrich
+method and some new tools. The delicate problem in the construction of a global
+solution, is the passage to the limit in exponential nonlinear term. To solve
+this problem, we use a polynomial approximation of the damping part and a new
+type of interpolation between $L^\infty(\mathbb{R}^+,L^2(\mathbb{R}^3))$ and
+the space of functions $f$ such that $(e^{\beta|f|^2}-1)|f|^2\in
+L^1(\mathbb{R}^3)$. Fourier analysis and standard techniques are used.",2103.05388v1
+2021-05-03,Enhanced and unenhanced dampings of Kolmogorov flow,"In the present study, Kolmogorov flow represents the stationary sinusoidal
+solution $(\sin y,0)$ to a two-dimensional spatially periodic Navier-Stokes
+system, driven by an external force. This system admits the additional
+non-stationary solution $(\sin y,0)+e^{-\nu t} (\sin y,0)$, which tends
+exponentially to the Kolmogorov flow at the minimum decay rate determined by
+the viscosity $\nu$. Enhanced damping or enhanced dissipation of the problem is
+obtained by presenting higher decay rate for the difference between a solution
+and the non-stationary basic solution. Moreover, for the understanding of the
+metastability problem in an explicit manner, a variety of exact solutions are
+presented to show enhanced and unenhanced dampings.",2105.00730v2
+2021-05-06,On Linear Damping Around Inhomogeneous Stationary States of the Vlasov-HMF Model,"We study the dynamics of perturbations around an inhomogeneous stationary
+state of the Vlasov-HMF (Hamiltonian Mean-Field) model, satisfying a linearized
+stability criterion (Penrose criterion). We consider solutions of the
+linearized equation around the steady state, and prove the algebraic decay in
+time of the Fourier modes of their density. We prove moreover that these
+solutions exhibit a scattering behavior to a modified state, implying a linear
+Landau damping effect with an algebraic rate of damping.",2105.02484v1
+2021-05-31,Blowup of Solutions to a Damped Euler Equation with Homogeneous Three-Point Boundary Condition,"It has been established that solutions to the inviscid Proudman-Johnson
+equation subject to a homogeneous three-point boundary condition can develop
+singularities in finite time. In this paper, we consider the possibility of
+singularity formation in solutions of the generalized, inviscid
+Proudman-Johnson equation with damping subject to the same homogeneous
+three-point boundary condition. In particular, we derive conditions the initial
+data must satisfy in order for solutions to blowup in finite time with either
+bounded or unbounded smooth damping term.",2106.00068v1
+2021-06-23,Damping of the Franz-Keldysh oscillations in the presence of disorder,"Franz-Keldysh oscillations of the optical absorption in the presence of
+short-range disorder are studied theoretically. The magnitude of the effect
+depends on the relation between the mean-free path in a zero field and the
+distance between the turning points in electric field. Damping of the
+Franz-Keldysh oscillations by the disorder develops at high absorption
+frequency. Effect of damping is amplified by the fact that, that electron and
+hole are most sensitive to the disorder near the turning points. This is
+because, near the turning points, velocities of electron and hole turn to zero.",2106.12691v1
+2021-07-01,Event-triggering mechanism to damp the linear wave equation,"This paper aims at proposing a sufficient matrix inequality condition to
+carry out the global exponential stability of the wave equation under an
+event-triggering mechanism that updates a damping source term. The damping is
+distributed in the whole space but sampled in time. The wellposedness of the
+closed-loop event-triggered control system is shown. Furthermore, the avoidance
+of Zeno behavior is ensured provided that the initial data are more regular.
+The interest of the results is drawn through some numerical simulations.",2107.00292v1
+2022-01-28,Quantum metrology with a non-linear kicked Mach-Zehnder interferometer,"We study the sensitivity of a Mach-Zehnder interferometer that contains in
+addition to the phase shifter a non-linear element. By including both elements
+in a cavity or a loop that the light transverses many times, a non-linear
+kicked version of the interferometer arises. We study its sensitivity as
+function of the phase shift, the kicking strength, the maximally reached
+average number of photons, and damping due to photon loss for an initial
+coherent state. We find that for vanishing damping Heisenberg-limited scaling
+of the sensitivity arises if squeezing dominates the total photon number. For
+small to moderate damping rates the non-linear kicks can considerably increase
+the sensitivity as measured by the quantum Fisher information per unit time.",2201.12255v1
+2022-02-27,The time asymptotic expansion for the compressible Euler equations with time-dependent damping,"In this paper, we study the compressible Euler equations with time-dependent
+damping $-\frac{1}{(1+t)^{\lambda}}\rho u$. We propose a time asymptotic
+expansion around the self-similar solution of the generalized porous media
+equation (GPME) and rigorously justify this expansion as $\lambda \in
+(\frac17,1)$. In other word, instead of the self-similar solution of GPME, the
+expansion is the best asymptotic profile of the solution to the compressible
+Euler equations with time-dependent damping.",2202.13385v1
+2022-03-30,A Toy Model for Damped Water Waves,"We consider a toy model for a damped water waves system in a domain $\Omega_t
+\subset \mathbb{T} \times \mathbb{R}$. The toy model is based on the
+paradifferential water waves equation derived in the work of
+Alazard-Burq-Zuily. The form of damping we utilize we utilize is a modified
+sponge layer proposed for the three-dimensional water waves system by Clamond,
+et. al. We show that, in the case of small Cauchy data, solutions to the toy
+model exhibit a quadratic lifespan. This is done via proving energy estimates
+with the energy being constructed from appropriately chosen vector fields.",2203.16645v1
+2022-05-10,Global attractor for the weakly damped forced Kawahara equation on the torus,"We study the long time behaviour of solutions for the weakly damped forced
+Kawahara equation on the torus. More precisely, we prove the existence of a
+global attractor in $L^2$, to which as time passes all solutions draw closer.
+In fact, we show that the global attractor turns out to lie in a smoother space
+$H^2$ and be bounded therein. Further, we give an upper bound of the size of
+the attractor in $H^2$ that depends only on the damping parameter and the norm
+of the forcing term.",2205.04642v1
+2022-10-24,The time asymptotic expansion for the compressible Euler equations with damping,"In 1992, Hsiao and Liu \cite{Hsiao-Liu-1} firstly showed that the solution to
+the compressible Euler equations with damping time-asymptotically converges to
+the diffusion wave $(\bar v, \bar u)$ of the porous media equation. In
+\cite{Geng-Huang-Jin-Wu}, we proposed a time-asymptotic expansion around the
+diffusion wave $(\bar v, \bar u)$, which is a better asymptotic profile than
+$(\bar v, \bar u)$. In this paper, we rigorously justify the time-asymptotic
+expansion by the approximate Green function method and the energy estimates.
+Moreover, the large time behavior of the solution to compressible Euler
+equations with damping is accurately characterized by the time asymptotic
+expansion.",2210.13157v1
+2023-02-09,A remark on the logarithmic decay of the damped wave and Schrödinger equations on a compact Riemannian manifold,"In this paper we consider a compact Riemannian manifold (M, g) of class C 1
+$\cap$ W 2,$\infty$ and the damped wave or Schr\""odinger equations on M , under
+the action of a damping function a = a(x). We establish the following fact: if
+the measure of the set {x $\in$ M ; a(x) = 0} is strictly positive, then the
+decay in time of the associated energy is at least logarithmic.",2302.04498v1
+2023-03-02,Using vibrating wire in non-linear regime as a thermometer in superfluid $^3$He-B,"Vibrating wires are common temperature probes in $^3$He experiments. By
+measuring mechanical resonance of a wire driven by AC current in magnetic field
+one can directly obtain temperature-dependent viscous damping. This is easy to
+do in a linear regime where wire velocity is small enough and damping force is
+proportional to velocity. At lowest temperatures in superfluid $^3$He-B a
+strong non-linear damping appears and linear regime shrinks to a very small
+velocity range. Expanding measurements to the non-linear area can significantly
+improve sensitivity. In this note I describe some technical details useful for
+analyzing such temperature measurements.",2303.01189v1
+2023-04-06,A turbulent study for a damped Navier-Stokes equation: turbulence and problems,"In this article we consider a damped version of the incompressible
+Navier-Stokes equations in the whole three-dimensional space with a
+divergence-free and time-independent external force. Within the framework of a
+well-prepared force and with a particular choice of the damping parameter, when
+the Grashof numbers are large enough, we are able to prove some estimates from
+below and from above between the fluid characteristic velocity and the energy
+dissipation rate according to the Kolmogorov dissipation law. Precisely, our
+main contribution concerns the estimate from below which is not often studied
+in the existing literature. Moreover, we address some remarks which open the
+door to a deep discussion on the validity of this theory of turbulence.",2304.03134v1
+2023-05-13,Global existence for a 3D Tropical Climate Model with damping and small initial data in $\dot H^{1/2}(\mathbb{R}^3)$,"We consider a 3D Tropical Climate Model with damping terms in the equation of
+the barotropic mode $u$ and in the equation of the first baroclinic mode $v$ of
+the velocity. The equation for the temperature $\theta$ is free from dampings.
+We prove global existence in time for this system assuming the initial data
+$(u_0, v_0,\theta_0)$ small, in terms of the homogeneous space $\dot
+H^{1/2}(\mathbb{R}^3)$.",2305.07964v1
+2023-06-21,The effect of singularities and damping on the spectra of photonic crystals,"Understanding the dispersive properties of photonic crystals is a fundamental
+and well-studied problem. However, the introduction of singular permittivities
+and damping complicates the otherwise straightforward theory. In this paper, we
+study photonic crystals with a Drude-Lorentz model for the permittivity,
+motivated by halide perovskites. We demonstrate how the introduction of
+singularities and damping affects the spectral band structure and show how to
+interpret the notion of a ""band gap"" in this setting. We present explicit
+solutions for a one-dimensional model and show how integral operators can be
+used to handle multi-dimensional systems.",2306.12254v1
+2023-07-25,Asymptotic behavior and life-span estimates for the damped inhomogeneous nonlinear Schrödinger equation,"We are interested in the behavior of solutions to the damped inhomogeneous
+nonlinear Schr\""odinger equation $ i\partial_tu+\Delta
+u+\mu|x|^{-b}|u|^{\alpha}u+iau=0$, $\mu \in\mathbb{C} $, $b>0$, $a \in
+\mathbb{C}$ such that $\Re \textit{e}(a) \geq 0$, $\alpha>0$. We establish
+lower and upper bound estimates of the life-span. In particular for $a\geq 0$,
+we obtain explicit values $a_*,\; a^*$ such that if $a<a_*$ then blow up
+occurs, while for $a>a^*,$ global existence holds. Also, we prove scattering
+results with precise decay rates for large damping. Some of the results are new
+even for $b=0.$",2307.13495v1
+2023-07-26,On nonlinear Landau damping and Gevrey regularity,"In this article we study the problem of nonlinear Landau damping for the
+Vlasov-Poisson equations on the torus. As our main result we show that for
+perturbations initially of size $\epsilon>0$ and time intervals
+$(0,\epsilon^{-N})$ one obtains nonlinear stability in regularity classes
+larger than Gevrey $3$, uniformly in $\epsilon$. As a complementary result we
+construct families of Sobolev regular initial data which exhibit nonlinear
+Landau damping. Our proof is based on the methods of Grenier, Nguyen and
+Rodnianski.",2307.14271v1
+2023-08-18,Damping for fractional wave equations and applications to water waves,"Motivated by numerically modeling surface waves for inviscid Euler equations,
+we analyze linear models for damped water waves and establish decay properties
+for the energy for sufficiently regular initial configurations. Our findings
+give the explicit decay rates for the energy, but do not address
+reflection/transmission of waves at the interface of the damping. Still for a
+subset of the models considered, this represents the first result proving the
+decay of the energy of the surface wave models.",2308.09288v1
+2023-08-30,Optimal decay for one-dimensional damped wave equations with potentials via a variant of Nash inequality,"The optimality of decay properties of the one-dimensional damped wave
+equations with potentials belonging to a certain class is discussed. The
+typical ingredient is a variant of Nash inequality which involves an invariant
+measure for the corresponding Schr\""odinger semigroup. This enables us to find
+a sharp decay estimate from above. Moreover, the use of a test function method
+with the Nash-type inequality provides the decay estimate from below. The
+diffusion phenomena for the damped wave equations with potentials are also
+considered.",2308.15680v1
+2023-09-15,Explicit solutions and linear inviscid damping in the Euler-Boussinesq equation near a stratified Couette flow in the periodic strip,"This short note provides explicit solutions to the linearized Boussinesq
+equations around the stably stratified Couette flow posed on
+$\mathbb{T}\times\mathbb{R}$. We consider the long-time behavior of such
+solutions and prove inviscid damping of the perturbed density and velocity
+field for any positive Richardson number, with optimal rates. The explicit
+solution is obtained through the limiting absorption principle whereas the
+inviscid damping is proved using oscillatory integral methods.",2309.08419v2
+2023-09-21,Beyond Qubits : An Extensive Noise Analysis for Qutrit Quantum Teleportation,"The four quantum noises Bit Flip, Phase Flip, Depolarization, and Amplitude
+Damping as well as any potential combinations of them are examined in this
+papers investigation of quantum teleportation using qutrit states. Among the
+above mentioned noises, we observed phase flip has highest fidelity. Compared
+to uncorrelated Amplitude Damping, we find that correlated Amplitude Damping
+performs two times better. Finally, we agreed that, for better fidelity, it is
+preferable to provide the same noise in channel state if noise is unavoidable.",2309.12163v1
+2023-12-22,Soliton resolution for the energy critical damped wave equations in the radial case,"We consider energy-critical damped wave equation \begin{equation*}
+\partial_{tt}u-\Delta u+\alpha \partial_t u=\left|u\right|^{\frac{4}{D-2}}u
+\end{equation*} with radial initial data in dimensions $D\geq 4$. The equation
+has a nontrivial radial stationary solution $W$, called the ground state, which
+is unique up to sign and scale. We prove that any bounded energy norm solution
+behaves asymptotically as a superposition of the modulated ground states and a
+radiation term. In the global case, particularly, the solution converges to a
+pure multi-bubble due to the damping effect.",2401.04115v2
+2024-02-18,Sharp lifespan estimate for the compressible Euler system with critical time-dependent damping in $\R^2$,"This paper concerns the long time existence to the smooth solutions of the
+compressible Euler system with critical time dependent damping in $\R^2$. We
+establish the sharp lifespan estimate from below, with respect to the small
+parameter of the initial perturbation. For this end, the vector fields
+$\widehat{Z}$ (defined below) are used instead of the usual one $Z$, to get
+better decay for the linear error terms. This idea may also apply to the long
+time behavior study of nonlinear wave equations with time-dependent damping.",2402.11516v1
+2024-02-28,Linear inviscid damping in the presence of an embedding eigenvalue,"In this paper, we investigate the long-time dynamics of the linearized 2-D
+Euler equations around a hyperbolic tangent flow $(\tanh y,0)$. A key
+difference compared to previous results is that the linearized operator has an
+embedding eigenvalue, which has a significant impact on the dynamics of the
+linearized system. For the first mode, the dynamics consists of there parts:
+non-decay part related to the eigenspace associated with the embedding
+eigenvalue, slow decay part due to the resolvent singularity, and fast decay
+part related to the inviscid damping. For higher modes, the dynamics is similar
+to the inviscid damping phenomena in the case without embedding eigenvalues.",2402.18229v1
+2024-03-19,Improved decay results for micropolar flows with nonlinear damping,"We examine the long-time behavior of solutions (and their derivatives) to the
+micropolar equations with nonlinear velocity damping. Additionally, we get a
+speed-up gain of $ t^{1/2} $ for the angular velocity, consistent with
+established findings for classic micropolar flows lacking nonlinear damping.
+Consequently, we also obtain a sharper result regarding the asymptotic
+stability of the micro-rotational velocity $\ww(\cdot,t)$. Related results of
+independent interest are also included.",2403.12885v1
+1994-05-02,Damped Lyman Alpha Systems vs. Cold + Hot Dark Matter,"Although the Cold + Hot Dark Matter (CHDM) cosmology provides perhaps the
+best fit of any model to all the available data at the current epoch, CHDM
+produces structure at relatively low redshifts and thus could be ruled out if
+there were evidence for formation of massive objects at high redshifts. Damped
+Ly$\alpha$ systems are abundant in quasar absorption spectra and thus provide
+possibly the most significant evidence for early structure formation, and thus
+perhaps the most stringent constraint on CHDM. Using the numbers of halos in
+N-body simulations to normalize Press-Schechter estimates of the number
+densities of protogalaxies as a function of redshift, we find that CHDM with
+$\Omega_c/\Omega_\nu/\Omega_b = 0.6/0.3/0.1$ is compatible with the damped
+Ly$\alpha$ data at $\le 2.5$, but that it is probably incompatible with the
+limited $z>3$ damped Ly$\alpha$ data. The situation is uncertain because there
+is very little data for $z>3$, and also it is unclear whether all damped
+Ly$\alpha$ systems are associated with collapsed protogalaxies. The predictions
+of CHDM are quite sensitive to the hot (neutrino) fraction, and we find that
+$\Omega_c/\Omega_\nu/\Omega_b = 0.675/0.25/0.075$ is compatible even with the
+$z>3$ data. This corresponds to lowering the neutrino mass from 6.8 to 5.7 eV,
+for $H_0=50\kmsMpc$. In CHDM, the higher redshift damped Ly$\alpha$ systems are
+predicted to have lower masses, which can be checked by measuring the velocity
+widths of the associated metal line systems.",9405003v1
+1995-03-24,High Redshift Lyman Limit and Damped Lyman-Alpha Absorbers,"We have obtained high signal:to:noise optical spectroscopy at 5\AA\
+resolution of 27 quasars from the APM z$>$4 quasar survey. The spectra have
+been analyzed to create new samples of high redshift Lyman-limit and damped
+Lyman-$\alpha$ absorbers. These data have been combined with published data
+sets in a study of the redshift evolution and the column density distribution
+function for absorbers with $\log$N(HI)$\ge17.5$, over the redshift range 0.01
+$<$ z $<$ 5. The main results are: \begin{itemize} \item Lyman limit systems:
+The data are well fit by a power law $N(z) = N_0(1 + z)^{\gamma}$ for the
+number density per unit redshift. For the first time intrinsic evolution is
+detected in the product of the absorption cross-section and comoving spatial
+number density for an $\Omega = 1$ Universe. We find $\gamma = 1.55$ ($\gamma =
+0.5$ for no evolution) and $N_0 = 0.27$ with $>$99.7\% confidence limits for
+$\gamma$ of 0.82 \& 2.37. \item Damped \lya systems: The APM QSOs provide a
+substantial increase in the redshift path available for damped surveys for
+$z>3$. Eleven candidate and three confirmed damped Ly$\alpha$ absorption
+systems, have been identified in the APM QSO spectra covering the redshift
+range $2.8\le z \le 4.4$ (11 with $z>3.5$). Combining the APM survey confirmed
+and candidate damped \lya absorbers with previous surveys, we find evidence for
+a turnover at z$\sim$3 or a flattening at z$\sim$2 in the cosmological mass
+density of neutral gas, $\Omega_g$. \end{itemize} The Lyman limit survey
+results are published in Storrie-Lombardi, et~al., 1994, ApJ, 427, L13. Here we
+describe the results for the DLA population of absorbers.",9503089v1
+1997-05-15,Cosmological Constraints from High-Redshift Damped Lyman-Alpha Systems,"Any viable cosmological model must produce enough structure at early epochs
+to explain the amount of gas associated with high-redshift damped Ly$\alpha$
+systems. We study the evolution of damped Ly$\alpha$ systems at redshifts $z\ge
+2$ in cold dark matter (CDM) and cold+hot dark matter (CDM+HDM) models using
+both N-body and hydrodynamic simulations. Our approach incorporates the effects
+of gas dynamics, and we find that all earlier estimates which assumed that all
+the baryons in dark matter halos would contribute to damped Ly$\alpha$
+absorption have overestimated the column density distribution $f(N)$ and the
+fraction of neutral dense gas $\Omega_g$ in damped Ly$\alpha$ systems. The
+differences are driven by ionization of hydrogen in the outskirts of galactic
+halos and by gaseous dissipation near the halo centers, and they tend to
+exacerbate the problem of late galaxy formation in CDM+HDM models. We only
+include systems up to the highest observed column density $N\sim 10^{21.8}$
+cm$^{-2}$ in the estimation of $\Omega_g$ for a fair comparison with data. If
+the observed $f(N)$ and $\Omega_g$ inferred from a small number of confirmed
+and candidate absorbers are robust, the amount of gas in damped Ly$\alpha$
+systems at high redshifts in the $\Omega_\nu=0.2$ CDM+HDM model falls well
+below the observations.",9705113v1
+2001-01-03,Galactic Chemical Abundances at z>3 I: First Results from the Echellette Spectrograph and Imager,"We present the first results from an ongoing survey to discover and measure
+the metallicity of z>3 damped Lya systems with the Echellette Spectrograph and
+Imager (ESI) on the Keck II telescope. Our motivation arises from a recent
+study on the damped Lya systems suggesting only mild evolution in the cosmic
+metallicity from z~2 to 4. The Echellette Spectrograph and Imager, which
+provides two complementary spectroscopic modes, is the ideal instrument for a
+z>3 damped Lya survey. We describe our observing strategy and report on the
+discovery and analysis of 5 new z>3 damped Lya systems acquired in a single
+night of observing. These observations further support the principal
+conclusions of the previous study: (1) the cosmic metallicity in neutral gas
+inferred from the damped Lya systems does not evolve significantly from z~2 to
+4; (2) the unweighted metallicity exhibits a statistically significant decrease
+with increasing redshift; and (3) not a single damped Lya system has a
+metallicity below [Fe/H]=-3. We discuss the implications of these results and
+comment on recent theoretical studies which attempt to explain the
+observations.",0101029v1
+2002-01-17,Self-shielding Effects on the Column Density Distribution of Damped Lyman Alpha Systems,"We calculate the column density distribution of damped Lyman alpha systems,
+modeled as spherical isothermal gaseous halos ionized by the external cosmic
+background. The effects of self-shielding introduce a hump in this
+distribution, at a column density N_{HI} \sim 1.6x10^{17} X^{-1} cm^{-2}, where
+X is the neutral fraction at the radius where self-shielding starts being
+important. The most recent compilation of the column density distribution by
+Storrie-Lombardi & Wolfe shows marginal evidence for the detection of this
+feature due to self-shielding, suggesting a value X \sim 10^{-3}. Assuming a
+photoionization rate \Gamma \sim 10^{-12} s^{-1} from the external ionizing
+background, the radius where self-shielding occurs is inferred to be about
+3.8kpc. If damped Lyman alpha systems consist of a clumpy medium, this should
+be interpreted as the typical size of the gas clumps in the region where they
+become self-shielding. Clumps of this size with typical column densities N_H
+\sim 3x10^{20} cm^{-2} would be in hydrostatic equilibrium at the
+characteristic photoionization temperature \sim 10^4 K if they do not contain
+dark matter. Since this size is similar to the overall radius of damped \lya
+systems in Cold Dark Matter models, where all halos are assumed to contain
+similar gas clouds producing damped absorbers, this suggests that the gas in
+damped absorbers is in fact not highly clumped.",0201275v2
+2002-04-30,Two-phase equilibrium and molecular hydrogen formation in damped Lyman-alpha systems,"Molecular hydrogen is quite underabundant in damped Lyman-alpha systems at
+high redshift, when compared to the interstellar medium near the Sun. This has
+been interpreted as implying that the gas in damped Lyman-alpha systems is
+warm. like the nearby neutral intercloud medium, rather than cool, as in the
+clouds which give rise to most H I absorption in the Milky Way. Other lines of
+evidence suggest that the gas in damped Lyman-alpha systems -- in whole or part
+-- is actually cool; spectroscopy of neutral and ionized carbon, discussed
+here, shows that the damped Lyman-alpha systems observed at lower redshift z
+$<$ 2.3 are largely cool, while those seen at z $>$ 2.8 are warm (though not
+devoid of H2). To interpret the observations of carbon and hydrogen we
+constructed detailed numerical models of H2 formation under the conditions of
+two-phase thermal equilibrium, like those which account for conditions near the
+Sun, but with varying metallicity, dust-gas ratio, $etc$. We find that the low
+metallicity of damped Lyman-alpha systems is enough to suppress H2 formation by
+many orders of magnitude even in cool diffuse clouds, as long as the ambient
+optical/uv radiation field is not too small. For very low metallicity and under
+the most diffuse conditions, H2 formation will be dominated by slow gas-phase
+processes not involving grains, and a minimum molecular fraction in the range
+$10^{-8}-10^{-7}$ is expected.",0204515v1
+2003-05-12,Ordinary and Viscosity-Damped MHD Turbulence,"We compare the properties of ordinary strong magnetohydrodynamic (MHD)
+turbulence in a strongly magnetized medium with the recently discovered
+viscosity-damped regime. We focus on energy spectra, anisotropy, and
+intermittency. Our most surprising conclusion is that in ordinary strong MHD
+turbulence the velocity and magnetic fields show different high-order structure
+function scalings. Moreover this scaling depends on whether the intermittency
+is viewed in a global or local system of reference. This reconciles seemingly
+contradictory earlier results. On the other hand, the intermittency scaling for
+viscosity-damped turbulence is very different, and difficult to understand in
+terms of the usual phenomenological models for intermittency in turbulence. Our
+remaining results are in reasonable agreement with expectations. First, we find
+that our high resolution simulations for ordinary MHD turbulence show that the
+energy spectra are {\it compatible} with a Kolmogorov spectrum, while
+viscosity-damped turbulence shows a shallow $k^{-1}$ spectrum for the magnetic
+fluctuations. Second, a new numerical technique confirms that ordinary MHD
+turbulence exhibits Goldreich-Sridhar type anisotropy, while viscosity-damped
+MHD turbulence shows extremely anisotropic eddy structures. Finally, we show
+that many properties of incompressible turbulence for both the ordinary and
+viscosity-damped regimes carry over to the case of compressible turbulence.",0305212v2
+2003-09-17,Observational Tests of Damping by Resonant Absorption in Coronal Loop Oscillations,"One of the proposed damping mechanisms of coronal (transverse) loop
+oscillations in the kink-mode is resonant absorption as a result of the Alfven
+speed variation at the outer boundary of coronal loops. Analytical expressions
+for the period and damping time exist for loop models with thin non-uniform
+boundaries. Here we measure the thickness of the non-uniform layer in
+oscillating loops for 11 events, by forward-fitting of the cross-sectional
+density profile and line-of-sight integration to the cross-sectional fluxes
+observed with TRACE 171 A. This way we model the internal and external electron
+density of the coronal plasma in oscillating loops. This allows us to test the
+theoretically predicted damping rates for thin boundaries as function of the
+density ratio. We find that the density ratio predicted by the damping time is
+higher than the density ratio estimated from the background fluxes. The lower
+densities modeled from the background fluxes are likely to be a consequence of
+the neglected hotter plasma that is not detected with the TRACE 171 A filter.
+Taking these correction into account, resonant absorption predicts damping
+times of kink-mode oscillations that are commensurable with the observed ones
+and provides a new diagnostic of the density contrast of oscillating loops.",0309470v1
+2005-03-01,Metal Abundances in a Damped Lyman-alpha System Along Two Lines of Sight at z=0.93,"We study metal abundances in the z=0.9313 damped Lya system observed in the
+two lines-of-sight, A and B, toward the gravitationally-lensed double QSO
+HE0512-3329. Spatially resolved STIS spectra constrain the neutral-gas column
+density to be LogN(HI)=20.5 in both Aand B. UVES spectra (spectral resolution
+FWHM=9.8 km/s) show, in contrast, significant line-of-sight differences in the
+column densities of MnII and FeII; these are not due to observational
+systematics. We find that [Mn/H]=-1.44 and [Fe/H]=-1.52 in damped Lya system A,
+while [Mn/H]=-0.98 and [Fe/H]>-1.32, and possibly as high as [Fe/H] approx. -1
+in damped Lya system B. A careful assessment of possible systematic errors
+leads us to conclude that these transverse differences are significant at a 5
+sigma level or greater. Although nucleosynthesis effects may also be at play,
+we favor differential dust-depletion as the main mechanism producing the
+observed abundance gradient. The transverse separation is 5 kpc at the redshift
+of the absorber, which is also likely to be the lensing galaxy. The derived
+abundances therefore probe two opposite sides of a single galaxy hosting both
+damped Lya systems. This is the first time firm abundance constraints have been
+obtained for a single damped system probed by two lines-of-sight. The
+significance of this finding for the cosmic evolution of metals is discussed.",0503026v1
+2000-08-26,Adsorbate aggregation and relaxation of low-frequency vibrations,"We present a study of resonant vibrational coupling between adsorbates and an
+elastic substrate at low macroscopic coverages. In the first part of the paper
+we consider the situation when adsorbates form aggregates with high local
+coverage. Based upon our previously published theory, we derive formulas
+describing the damping rate of adsorbate vibrations for two cases of such
+aggregation: (i) adsorbates attached to step edges and (ii) adsorbates forming
+two-dimensional islands. We have shown that damping is governed by local
+coverage. Particularly, for a wide range of resonant frequencies, the damping
+rate of adsorbates forming well separated islands is described by the damping
+rate formula for a periodic overlayer with the coverage equal to the local
+coverage in the island. The second part of the paper is devoted to facilitating
+the evaluation of damping rates for a disordered overlayer. The formula
+describing the damping rate involves the parameter $\beta$ which is related to
+the local density of phonon states at the substrate surface and does not allow
+a closed-form representation. For substrates of isotropic and cubic symmetries,
+we have developed a good analytical approximation to this parameter. For a vast
+majority of cubic substrates the difference between the analytical
+approximation and numerical calculation does not exceed 4%.",0008389v1
+2004-10-26,Mean-field treatment of the damping of the oscillations of a 1D Bose gas in an optical lattice,"We present a theoretical treatment of the surprisingly large damping observed
+recently in one-dimensional Bose-Einstein atomic condensates in optical
+lattices. We show that time-dependent Hartree-Fock-Bogoliubov (HFB)
+calculations can describe qualitatively the main features of the damping
+observed over a range of lattice depths. We also derive a formula of the
+fluctuation-dissipation type for the damping, based on a picture in which the
+coherent motion of the condensate atoms is disrupted as they try to flow
+through the random local potential created by the irregular motion of
+noncondensate atoms. We expect this irregular motion to result from the
+well-known dynamical instability exhibited by the mean-field theory for these
+systems. When parameters for the characteristic strength and correlation times
+of the fluctuations, obtained from the HFB calculations, are substituted in the
+damping formula, we find very good agreement with the experimentally-observed
+damping, as long as the lattice is shallow enough for the fraction of atoms in
+the Mott insulator phase to be negligible. We also include, for completeness,
+the results of other calculations based on the Gutzwiller ansatz, which appear
+to work better for the deeper lattices.",0410677v4
+1998-10-16,Fermion Damping in a Fermion-Scalar Plasma,"In this article we study the dynamics of fermions in a fermion-scalar plasma.
+We begin by obtaining the effective in-medium Dirac equation in real time which
+is fully renormalized and causal and leads to the initial value problem. For a
+heavy scalar we find the novel result that the decay of the scalar into fermion
+pairs in the medium leads to damping of the fermionic excitations and their
+in-medium propagation as quasiparticles. That is, the fermions acquire a width
+due to the decay of the heavier scalar in the medium. We find the damping rate
+to lowest order in the Yukawa coupling for arbitrary values of scalar and
+fermion masses, temperature and fermion momentum. An all-order expression for
+the damping rate in terms of the exact quasiparticle wave functions is
+established. A kinetic Boltzmann approach to the relaxation of the fermionic
+distribution function confirms the damping of fermionic excitations as a
+consequence of the induced decay of heavy scalars in the medium. A
+linearization of the Boltzmann equation near equilibrium clearly displays the
+relationship between the damping rate of fermionic mean fields and the fermion
+interaction rate to lowest order in the Yukawa coupling directly in real time.",9810393v2
+2006-01-06,Wave energy localization by self-focusing in large molecular structures: a damped stochastic discrete nonlinear Schroedinger equation model,"Wave self-focusing in molecular systems subject to thermal effects, such as
+thin molecular films and long biomolecules, can be modeled by stochastic
+versions of the Discrete Self-Trapping equation of Eilbeck, Lomdahl and Scott,
+and this can be approximated by continuum limits in the form of stochastic
+nonlinear Schroedinger equations.
+  Previous studies directed at the SNLS approximations have indicated that the
+self-focusing of wave energy to highly localized states can be inhibited by
+phase noise (modeling thermal effects) and can be restored by phase damping
+(modeling heat radiation).
+  We show that the continuum limit is probably ill-posed in the presence of
+spatially uncorrelated noise, at least with little or no damping, so that
+discrete models need to be addressed directly. Also, as has been noted by other
+authors, omission of damping produces highly unphysical results.
+  Numerical results are presented for the first time for the discrete models
+including the highly nonlinear damping term, and new numerical methods are
+introduced for this purpose. Previous conjectures are in general confirmed, and
+the damping is shown to strongly stabilize the highly localized states of the
+discrete models. It appears that the previously noted inhibition of nonlinear
+wave phenomena by noise is an artifact of modeling that includes the effects of
+heat, but not of heat loss.",0601017v1
+2007-11-15,Effect of the steady flow on spatial damping of small-amplitude prominence oscillations,"Aims. Taking account of steady flow in solar prominences, we study its
+effects on spatial damping of small-amplitude non-adiabatic magnetoacoustic
+waves in a homogeneous, isothermal, and unbounded prominence plasma. Methods.
+We model the typical feature of observed damped oscillatory motion in
+prominences, removing the adiabaticity assumption through thermal conduction,
+radiation and heating. Invoking steady flow in MHD equations, we linearise them
+under small-amplitude approximation and obtain a new general dispersion
+relation for linear non-adiabatic magnetoacoustic waves in prominences Results.
+The presence of steady flow breaks the symmetry of forward and backward
+propagating MHD wave modes in prominences. The steady flow has dramatic
+influence on the propagation and damping of magnetoacoustic and thermal waves.
+Depending upon the direction and strength of flow the magnetoacoustic and
+thermal modes can show both the features of wave amplification and damping. At
+the wave period of 5 min where the photospheric power is maximum, the slow mode
+shows wave amplification. However, in the absence of steady flow the slow mode
+wave shows damping. Conclusions. For the wave period between 5 min and 15 min,
+the amplification length for slow mode, in the case of prominence regime 1.1,
+varies between 3.4*10^11 m to 2*10^12 m. Dramatic influence of steady flow on
+small-amplitude prominence oscillations is likely to play an important role in
+both wave detection and prominence seismology.",0711.2353v1
+2011-04-13,Evolution of inclined planets in three-dimensional radiative discs,"While planets in the solar system only have a low inclination with respect to
+the ecliptic there is mounting evidence that in extrasolar systems the
+inclination can be very high, at least for close-in planets. One process to
+alter the inclination of a planet is through planet-disc interactions. Recent
+simulations considering radiative transport have shown that the evolution of
+migration and eccentricity can strongly depend on the thermodynamic state of
+the disc. We extend previous studies to investigate the planet-disc
+interactions of fixed and moving planets on inclined and eccentric orbits. We
+also analyse the effect of the disc's thermodynamic properties on the orbital
+evolution of embedded planets in detail. The protoplanetary disc is modelled as
+a viscous gas where the internally produced dissipation is transported by
+radiation. For locally isothermal discs, we confirm previous results and find
+inclination damping and inward migration for planetary cores. For low
+inclinations i < 2 H/r, the damping is exponential, while di/dt is proportional
+to i^-2 for larger i. For radiative discs, the planetary migration is very
+limited, as long as their inclination exceeds a certain threshold. If the
+inclination is damped below this threshold, planetary cores with a mass up to
+approximately 33 Earth masses start to migrate outwards, while larger cores
+migrate inwards right from the start. The inclination is damped for all
+analysed planet masses. In a viscous disc an initial inclination of embedded
+planets will be damped for all planet masses. This damping occurs on timescales
+that are shorter than the migration time. If the inclination lies beneath a
+certain threshold, the outward migration in radiative discs is not handicapped.
+Outward migration is strongest for circular and non-inclined orbits.",1104.2408v1
+2011-07-12,Mode conversion of radiatively damped magnetogravity waves in the solar chromosphere,"Modelling of adiabatic gravity wave propagation in the solar atmosphere
+showed that mode conversion to field guided acoustic waves or Alfv\'en waves
+was possible in the presence of highly inclined magnetic fields. This work aims
+to extend the previous adiabatic study, exploring the consequences of radiative
+damping on the propagation and mode conversion of gravity waves in the solar
+atmosphere. We model gravity waves in a VAL-C atmosphere, subject to a uniform,
+and arbitrarily orientated magnetic field, using the Newton cooling
+approximation for radiatively damped propagation. The results indicate that the
+mode conversion pathways identified in the adiabatic study are maintained in
+the presence of damping. The wave energy fluxes are highly sensitive to the
+form of the height dependence of the radiative damping time. While simulations
+starting from 0.2 Mm result in modest flux attenuation compared to the
+adiabatic results, short damping times expected in the low photosphere
+effectively suppress gravity waves in simulations starting at the base of the
+photosphere. It is difficult to reconcile our results and observations of
+propagating gravity waves with significant energy flux at photospheric heights
+unless they are generated in situ, and even then, why they are observed to be
+propagating as low as 70 km where gravity waves should be radiatively
+overdamped.",1107.2208v1
+2013-09-23,Phonon-mediated damping of mechanical vibrations in a finite atomic chain coupled to an outer environment,"We study phonon-mediated damping of mechanical vibrations in a finite
+quantum-mechanical atomic-chain model. Our study is motivated by the quest to
+understand the quality factors (Q) of nanomechanical resonators and
+nanoelectromechanical systems (NEMS), as well as actual experiments with
+suspended atomic chains and molecular junctions. We consider a finite atomic
+chain which is coupled to a zero-temperature outer environment, modeled as two
+additional semi-infinite chains, thus inducing ""clamping-losses"". Weak coupling
+to the outer environment ensures that the clamping losses are small, and that
+the initially discrete nature of the phonon spectrum is approximately
+maintained. We then consider a phonon damping process known as ""Landau-Rumer
+damping"", where phonons in the excited mode of vibration decay into other modes
+through anharmonic phonon-phonon interaction. The approximately discrete nature
+of the phonon spectrum leads to sharp nonmonotonic changes in Q as parameters
+are varied, and to the appearance of resonances in the damping. The latter
+correspond to the existence of decay processes where the participating phonons
+approximately conserve energy. We explore means to control the damping by
+changing either the number of atoms in the chains or the ratio between the
+longitudinal and transverse speeds of sound, thereby suggesting future
+experiments to observe this resonance-like behavior.",1309.5772v1
+2014-04-01,Stellar dynamics in gas: The role of gas damping,"In this paper, we consider how gas damping affects the dynamical evolution of
+gas-embedded star clusters. Using a simple three-component (i.e. one gas and
+two stellar components) model, we compare the rates of mass segregation due to
+two-body relaxation, accretion from the interstellar medium, and gas dynamical
+friction in both the supersonic and subsonic regimes. Using observational data
+in the literature, we apply our analytic predictions to two different
+astrophysical environments, namely galactic nuclei and young open star
+clusters. Our analytic results are then tested using numerical simulations
+performed with the NBSymple code, modified by an additional deceleration term
+to model the damping effects of the gas.
+  The results of our simulations are in reasonable agreement with our analytic
+predictions, and demonstrate that gas damping can significantly accelerate the
+rate of mass segregation. A stable state of approximate energy equilibrium
+cannot be achieved in our model if gas damping is present, even if Spitzer's
+Criterion is satisfied. This instability drives the continued dynamical
+decoupling and subsequent ejection (and/or collisions) of the more massive
+population. Unlike two-body relaxation, gas damping causes overall cluster
+contraction, reducing both the core and half-mass radii. If the cluster is mass
+segregated (and/or the gas density is highest at the cluster centre), the
+latter contracts faster than the former, accelerating the rate of core
+collapse.",1404.0379v1
+2014-04-26,Landau damping effects on dust-acoustic solitary waves in a dusty negative-ion plasma,"The nonlinear theory of dust-acoustic waves (DAWs) with Landau damping is
+studied in an unmagnetized dusty negative-ion plasma in the extreme conditions
+when the free electrons are absent. The cold massive charged dusts are
+described by fluid equations, whereas the two-species of ions (positive and
+negative) are described by the kinetic Vlasov equations. A Korteweg de-Vries
+(KdV) equation with Landau damping, governing the dynamics of weakly nonlinear
+and weakly dispersive DAWs, is derived following Ott and Sudan [Phys. Fluids
+{\bf 12}, 2388 (1969)]. It is shown that for some typical laboratory and space
+plasmas, the Landau damping (and the nonlinear) effects are more pronounced
+than the finite Debye length (dispersive) effects for which the KdV soliton
+theory is not applicable to DAWs in dusty pair-ion plasmas. The properties of
+the linear phase velocity, solitary wave amplitudes (in presence and absence of
+the Landau damping) as well as the Landau damping rate are studied with the
+effects of the positive ion to dust density ratio $(\mu_{pd})$ as well as the
+ratios of positive to negative ion temperatures $(\sigma)$ and masses $(m)$.",1404.6623v3
+2015-03-31,Damping of Confined Excitations Modes of 1D Condensates in an Optical Lattice,"We study the damping of the collective excitations of Bose-Einstein
+condensates in a harmonic trap potential loaded in an optical lattice. In the
+presence of a confining potential the system is non-homogeneous and the
+collective excitations are characterized by a set of discrete confined
+phonon-like excitations. We derive a general convenient analytical description
+for the damping rate, which takes into account, the trapping potential and the
+optical lattice, for the Landau and Beliaev processes at any temperature, $T$.
+At high temperature or weak spatial confinement, we show that both mechanisms
+display linear dependence on $T$. In the quantum limit, we found that the
+Landau damping is exponentially suppressed at low temperatures and the total
+damping is independent of $T$. Our theoretical predictions for the damping rate
+under thermal regime is in completely correspondence with the experimental
+values reported for 1D condensate of sodium atoms. We show that the laser
+intensity can tune the collision process, allowing a \textit{resonant effect}
+for the condensate lifetime. Also, we study the influence of the attractive or
+repulsive non-linear terms on the decay rate of the collective excitations. A
+general expression of the renormalized Goldstone frequency has been obtained as
+a function of the 1D non-linear self-interaction parameter, laser intensity and
+temperature.",1503.08884v2
+2015-08-06,On the spatial scales of wave heating in the solar chromosphere,"Dissipation of magnetohydrodynamic (MHD) wave energy has been proposed as a
+viable heating mechanism in the solar chromospheric plasma. Here, we use a
+simplified one-dimensional model of the chromosphere to theoretically
+investigate the physical processes and the spatial scales that are required for
+the efficient dissipation of Alfv\'en waves and slow magnetoacoustic waves. We
+consider the governing equations for a partially ionized hydrogen-helium plasma
+in the single-fluid MHD approximation and include realistic wave damping
+mechanisms that may operate in the chromosphere, namely Ohmic and ambipolar
+magnetic diffusion, viscosity, thermal conduction, and radiative losses. We
+perform an analytic local study in the limit of small amplitudes to
+approximately derive the lengthscales for critical damping and efficient
+dissipation of MHD wave energy. We find that the critical dissipation
+lengthscale for Alfv\'en waves depends strongly on the magnetic field strength
+and ranges from 10~m to 1~km for realistic field strengths. The damping of
+Alfv\'en waves is dominated by Ohmic diffusion for weak magnetic field and low
+heights in the chromosphere, and by ambipolar diffusion for strong magnetic
+field and medium/large heights in the chromosphere. Conversely, the damping of
+slow magnetoacoustic waves is less efficient, and spatial scales shorter than
+10~m are required for critical damping. Thermal conduction and viscosity govern
+the damping of slow magnetoacoustic waves and play an equally important role at
+all heights. These results indicate that the spatial scales at which strong
+wave heating may work in the chromosphere are currently unresolved by
+observations.",1508.01497v1
+2015-11-11,A statistical study of decaying kink oscillations detected using SDO/AIA,"Despite intensive studies of kink oscillations of coronal loops in the last
+decade, a large scale statistically significant investigation of the
+oscillation parameters has not been made using data from the Solar Dynamics
+Observatory (SDO).
+  We carry out a statistical study of kink oscillations using Extreme
+Ultra-Violet (EUV) imaging data from a previously compiled catalogue.
+  We analysed 58 kink oscillation events observed by the Atmospheric Imaging
+Assembly (AIA) onboard SDO during its first four years of operation
+(2010-2014). Parameters of the oscillations, including the initial apparent
+amplitude, period, length of the oscillating loop, and damping are studied for
+120 individual loop oscillations.
+  Analysis of the initial loop displacement and oscillation amplitude leads to
+the conclusion that the initial loop displacement prescribes the initial
+amplitude of oscillation in general. The period is found to scale with the loop
+length, and a linear fit of the data cloud gives a kink speed of Ck
+=(1330+/-50) km s-1 . The main body of the data corresponds to kink speeds in
+the range Ck =(800-3300) km s-1. Measurements of 52 exponential damping times
+were made, and it was noted that at least 22 of the damping profiles may be
+better approximated by a combination of non-exponential and exponential
+profiles, rather than a purely exponential damping envelope. There are an
+additional 10 cases where the profile appears to be purely non-exponential, and
+no damping time was measured. A scaling of the exponential damping time with
+the period is found, following the previously established linear scaling
+between these two parameters.",1511.03558v1
+2016-03-01,A comparative study of protocols for secure quantum communication under noisy environment: single-qubit-based protocols versus entangled-state-based protocols,"The effect of noise on various protocols of secure quantum communication has
+been studied. Specifically, we have investigated the effect of amplitude
+damping, phase damping, squeezed generalized amplitude damping, Pauli type as
+well as various collective noise models on the protocols of quantum key
+distribution, quantum key agreement,quantum secure direct quantum communication
+and quantum dialogue. From each type of protocol of secure quantum
+communication, we have chosen two protocols for our comparative study; one
+based on single qubit states and the other one on entangled states. The
+comparative study reported here has revealed that single-qubit-based schemes
+are generally found to perform better in the presence of amplitude damping,
+phase damping, squeezed generalized amplitude damping noises, while
+entanglement-based protocols turn out to be preferable in the presence of
+collective noises. It is also observed that the effect of noise entirely
+depends upon the number of rounds of quantum communication involved in a scheme
+of quantum communication. Further, it is observed that squeezing, a completely
+quantum mechanical resource present in the squeezed generalized amplitude
+channel, can be used in a beneficial way as it may yield higher fidelity
+compared to the corresponding zero squeezing case.",1603.00178v1
+2016-11-17,A stable partitioned FSI algorithm for rigid bodies and incompressible flow. Part I: Model problem analysis,"A stable partitioned algorithm is developed for fluid-structure interaction
+(FSI) problems involving viscous incompressible flow and rigid bodies. This
+{\em added-mass partitioned} (AMP) algorithm remains stable, without
+sub-iterations, for light and even zero mass rigid bodies when added-mass and
+viscous added-damping effects are large. The scheme is based on a generalized
+Robin interface condition for the fluid pressure that includes terms involving
+the linear acceleration and angular acceleration of the rigid body. Added-mass
+effects are handled in the Robin condition by inclusion of a boundary integral
+term that depends on the pressure. Added-damping effects due to the viscous
+shear forces on the body are treated by inclusion of added-damping tensors that
+are derived through a linearization of the integrals defining the force and
+torque. Added-damping effects may be important at low Reynolds number, or, for
+example, in the case of a rotating cylinder or rotating sphere when the
+rotational moments of inertia are small. In this first part of a two-part
+series, the properties of the AMP scheme are motivated and evaluated through
+the development and analysis of some model problems. The analysis shows when
+and why the traditional partitioned scheme becomes unstable due to either
+added-mass or added-damping effects. The analysis also identifies the proper
+form of the added-damping which depends on the discrete time-step and the
+grid-spacing normal to the rigid body. The results of the analysis are
+confirmed with numerical simulations that also demonstrate a second-order
+accurate implementation of the AMP scheme.",1611.05711v1
+2017-01-30,Torsional Alfvén resonances as an efficient damping mechanism for non-radial oscillations in red giant stars,"Stars are self-gravitating fluids in which pressure, buoyancy, rotation and
+magnetic fields provide the restoring forces for global modes of oscillation.
+Pressure and buoyancy energetically dominate, while rotation and magnetism are
+generally assumed to be weak perturbations and often ignored. However,
+observations of anomalously weak dipole mode amplitudes in red giant stars
+suggest that a substantial fraction of these are subject to an additional
+source of damping localised to their core region, with indirect evidence
+pointing to the role of a deeply buried magnetic field. It is also known that
+in many instances the gravity-mode character of affected modes is preserved,
+but so far no effective damping mechanism has been proposed that accommodates
+this aspect. Here we present such a mechanism, which damps the oscillations of
+stars harbouring magnetised cores via resonant interactions with standing
+Alfv\'en modes of high harmonic index. The damping rates produced by this
+mechanism are quantitatively on par with those associated with turbulent
+convection, and in the range required to explain observations, for realistic
+stellar models and magnetic field strengths. Our results suggest that magnetic
+fields can provide an efficient means of damping stellar oscillations without
+needing to disrupt the internal structure of the modes, and lay the groundwork
+for an extension of the theory of global stellar oscillations that incorporates
+these effects.",1701.08771v1
+2018-03-30,Damping of gravitational waves in a viscous Universe and its implication for dark matter self-interactions,"It is well known that a gravitational wave (GW) experiences the damping
+effect when it propagates in a fluid with nonzero shear viscosity. In this
+paper, we propose a new method to constrain the GW damping rate and thus the
+fluid shear viscosity. By defining the effective distance which incorporates
+damping effects, we can transform the GW strain expression in a viscous
+Universe into the same form as that in a perfect fluid. Therefore, the
+constraints of the luminosity distances from the observed GW events by LIGO and
+Virgo can be directly applied to the effective distances in our formalism. We
+exploit the lognormal likelihoods for the available GW effective distances and
+a Gaussian likelihood for the luminosity distance inferred from the
+electromagnetic radiation observation of the binary neutron star merger event
+GW170817. Our fittings show no obvious damping effects in the current GW data,
+and the upper limit on the damping rate with the combined data is $6.75 \times
+10^{-4}\,{\rm Mpc}^{-1}$ at 95\% confidence level. By assuming that the dark
+matter self-scatterings are efficient enough for the hydrodynamic description
+to be valid, we find that a GW event from its source at a luminosity distance
+$D\gtrsim 10^4\;\rm Mpc$ can be used to put a constraint on the dark matter
+self-interactions.",1803.11397v1
+2018-05-29,Basic microscopic plasma physics from N-body mechanics,"Computing is not understanding. This is exemplified by the multiple and
+discordant interpretations of Landau damping still present after seventy years.
+For long deemed impossible, the mechanical N-body description of this damping,
+not only enables its rigorous and simple calculation, but makes unequivocal and
+intuitive its interpretation as the synchronization of almost resonant passing
+particles. This synchronization justifies mechanically why a single formula
+applies to both Landau growth and damping. As to the electrostatic potential,
+the phase mixing of many beam modes produces Landau damping, but it is
+unexpectedly essential for Landau growth too. Moreover, collisions play an
+essential role in collisionless plasmas. In particular, Debye shielding results
+from a cooperative dynamical self-organization process, where ""collisional""
+deflections due to a given electron diminish the apparent number of charges
+about it. The finite value of exponentiation rates due to collisions is crucial
+for the equivalent of the van Kampen phase mixing to occur in the N-body
+system. The N-body approach incorporates spontaneous emission naturally, whose
+compound effect with Landau damping drives a thermalization of Langmuir waves.
+O'Neil's damping with trapping typical of initially large enough Langmuir waves
+results from a phase transition. As to collisional transport, there is a smooth
+connection between impact parameters where the two-body Rutherford picture is
+correct, and those where a collective description is mandatory. The N-body
+approach reveals two important features of the Vlasovian limit: it is singular
+and it corresponds to a renormalized description of the actual N-body dynamics.",1805.11408v2
+2018-08-22,"Constructing a boosted, spinning black hole in the damped harmonic gauge","The damped harmonic gauge is important for numerical relativity computations
+based on the generalized harmonic formulation of Einstein's equations, and is
+used to reduce coordinate distortions near binary black hole mergers. However,
+currently there is no prescription to construct quasiequilibrium binary black
+hole initial data in this gauge. Instead, initial data are typically
+constructed using a superposition of two boosted analytic single black hole
+solutions as free data in the solution of the constraint equations. Then, a
+smooth time-dependent gauge transformation is done early in the evolution to
+move into the damped harmonic gauge. Using this strategy to produce initial
+data in damped harmonic gauge would require the solution of a single black hole
+in this gauge, which is not known analytically. In this work we construct a
+single boosted, spinning, equilibrium BH in damped harmonic coordinates as a
+regular time-independent coordinate transformation from Kerr-Schild
+coordinates. To do this, we derive and solve a set of 4 coupled, nonlinear,
+elliptic equations for this transformation, with appropriate boundary
+conditions. This solution can now be used in the construction of damped
+harmonic initial data for binary black holes.",1808.07490v3
+2018-12-13,Neutrino damping in a fermion and scalar background,"We consider the propagation of a neutrino in a background composed of a
+scalar particle and a fermion using a simple model for the coupling of the form
+$\lambda\bar f_R\nu_L\phi$. In the presence of these interactions there can be
+damping terms in the neutrino effective potential and index of refraction. We
+calculate the imaginary part of the neutrino self-energy in this case, from
+which the damping terms are determined. The results are useful in the context
+of Dark Matter-neutrino interaction models in which the scalar and/or fermion
+constitute the dark-matter. The corresponding formulas for models in which the
+scalar particle couples to two neutrinos via a coupling of the form
+$\lambda^{(\nu\nu\phi)}\bar\nu^c_R\nu_L\phi$ are then obtained as a special
+case, which can be important also in the context of neutrino collective
+oscillations in a supernova and in the Early Universe hot plasma before
+neutrino decoupling. A particular feature of our results is that the damping
+term in a $\nu\phi$ background is independent of the antineutrino-neutrino
+asymmetry in the background. Therefore, the relative importance of the damping
+term may be more significant if the neutrino-antineutrino asymmetry in the
+background is small, because the leading $Z$-exchange and $\phi$-exchange
+contributions to the effective potential, which are proportional to the
+neutrino-antineutrino asymmetry, are suppressed in that case, while the damping
+term is not.",1812.05672v2
+2019-04-25,High Spin-Wave Propagation Length Consistent with Low Damping in a Metallic Ferromagnet,"We report ultra-low intrinsic magnetic damping in
+Co$_{\text{25}}$Fe$_{\text{75}}$ heterostructures, reaching the low $10^{-4}$
+regime at room temperature. By using a broadband ferromagnetic resonance
+technique, we extracted the dynamic magnetic properties of several
+Co$_{\text{25}}$Fe$_{\text{75}}$-based heterostructures with varying
+ferromagnetic layer thickness. By estimating the eddy current contribution to
+damping, measuring radiative damping and spin pumping effects, we found the
+intrinsic damping of a 26\,nm thick sample to be $$\alpha_{\mathrm{0}} \lesssim
+3.18\times10^{-4}$. Furthermore, using Brillouin light scattering microscopy we
+measured spin-wave propagation lengths of up to $(21\pm1)\,\mathrm{\mu m}$ in a
+26 nm thick Co$_{\text{25}}$Fe$_{\text{75}}$ heterostructure at room
+temperature, which is in excellent agreement with the measured damping.",1904.11321v3
+2019-11-02,Soft contribution to the damping rate of a hard photon in a weakly magnetized hot medium,"We consider weakly magnetized hot QED plasma comprising electrons and
+positrons. There are three distinct dispersive (longitudinal and two
+transverse) modes of a photon in a thermo-magnetic medium. At lowest order in
+coupling constant, photon is damped in this medium via Compton scattering and
+pair creation process. We evaluate the damping rate of hard photon by
+calculating the imaginary part of the each transverse dispersive modes in a
+thermo-magnetic QED medium. We note that one of the fermions in the loop of
+one-loop photon self-energy is considered as soft and the other one is hard.
+Considering the resummed fermion propagator in a weakly magnetized medium for
+the soft fermion and the Schwinger propagator for hard fermion, we calculate
+the soft contribution to the damping rate of hard photon. In weak field
+approximation the thermal and thermo-magnetic contributions to damping rate get
+separated out for each transverse dispersive mode. The total damping rate for
+each dispersive mode in presence of magnetic field is found to be reduced than
+that of the thermal one. This formalism can easily be extended to QCD plasma.",1911.00744v2
+2020-09-25,Temperature dependence of the damping parameter in the ferrimagnet Gd$_3$Fe$_5$O$_{12}$,"The damping parameter ${\alpha}_{\text{FM}}$ in ferrimagnets defined
+according to the conventional practice for ferromagnets is known to be strongly
+temperature dependent and diverge at the angular momentum compensation
+temperature, where the net angular momentum vanishes. However, recent
+theoretical and experimental developments on ferrimagnetic metals suggest that
+the damping parameter can be defined in such a way, which we denote by
+${\alpha}_{\text{FiM}}$, that it is free of the diverging anomaly at the
+angular momentum compensation point and is little dependent on temperature. To
+further understand the temperature dependence of the damping parameter in
+ferrimagnets, we analyze several data sets from literature for a ferrimagnetic
+insulator, gadolinium iron garnet, by using the two different definitions of
+the damping parameter. Using two methods to estimate the individual sublattice
+magnetizations, which yield results consistent with each other, we found that
+in all the used data sets, the damping parameter ${\alpha}_{\text{FiM}}$ does
+not increase at the angular compensation temperature and shows no anomaly
+whereas the conventionally defined ${\alpha}_{\text{FM}}$ is strongly dependent
+on the temperature.",2009.12073v2
+2020-09-25,A Complex Stiffness Human Impedance Model with Customizable Exoskeleton Control,"The natural impedance, or dynamic relationship between force and motion, of a
+human operator can determine the stability of exoskeletons that use
+interaction-torque feedback to amplify human strength. While human impedance is
+typically modelled as a linear system, our experiments on a single-joint
+exoskeleton testbed involving 10 human subjects show evidence of nonlinear
+behavior: a low-frequency asymptotic phase for the dynamic stiffness of the
+human that is different than the expected zero, and an unexpectedly consistent
+damping ratio as the stiffness and inertia vary. To explain these observations,
+this paper considers a new frequency-domain model of the human joint dynamics
+featuring complex value stiffness comprising a real stiffness term and a
+hysteretic damping term. Using a statistical F-test we show that the hysteretic
+damping term is not only significant but is even more significant than the
+linear damping term. Further analysis reveals a linear trend linking hysteretic
+damping and the real part of the stiffness, which allows us to simplify the
+complex stiffness model down to a 1-parameter system. Then, we introduce and
+demonstrate a customizable fractional-order controller that exploits this
+hysteretic damping behavior to improve strength amplification bandwidth while
+maintaining stability, and explore a tuning approach which ensures that this
+stability property is robust to muscle co-contraction for each individual.",2009.12446v1
+2020-11-26,On the stabilization of breather-type solutions of the damped higher order nonlinear Schrödinger equation,"Spatially periodic breather solutions (SPBs) of the nonlinear Schr\""o\-dinger
+(NLS) equation are frequently used to model rogue waves and are typically
+unstable. In this paper we study the effects of dissipation and higher order
+nonlinearities on the stabilization of both single and multi-mode SPBs in the
+framework of a damped higher order NLS (HONLS) equation. We observe the onset
+of novel instabilities associated with the development of critical states which
+result from symmetry breaking in the damped HONLS system. We broaden the
+Floquet characterization of instabilities of solutions of the NLS equation,
+using an even 3-phase solution of the NLS as an example, to show instabilities
+are associated with degenerate complex elements of both the periodic and
+continuous Floquet spectrum. As a result the Floquet criteria for the
+stabilization of a solution of the damped HONLS centers around the elimination
+of all complex degenerate elements of the spectrum. For an initial SPB with a
+given mode structure, a perturbation analysis shows that for short time only
+the complex double points associated with resonant modes split under the damped
+HONLS while those associated with nonresonant modes remain effectively closed.
+The corresponding damped HONLS numerical experiments corroborate that
+instabilities associated with nonresonant modes persist on a longer time scale
+than the instabilities associated with resonant modes.",2011.13334v1
+2020-12-22,Comparison of local and global gyrokinetic calculations of collisionless zonal flow damping in quasi-symmetric stellarators,"The linear collisionless damping of zonal flows is calculated for
+quasi-symmetric stellarator equilibria in flux-tube, flux-surface, and
+full-volume geometry. Equilibria are studied from the quasi-helical symmetry
+configuration of the Helically Symmetric eXperiment (HSX), a broken symmetry
+configuration of HSX, and the quasi-axial symmetry geometry of the National
+Compact Stellarator eXperiment (NCSX). Zonal flow oscillations and long-time
+damping affect the zonal flow evolution, and the zonal flow residual goes to
+zero for small radial wavenumber. The oscillation frequency and damping rate
+depend on the bounce-averaged radial particle drift in accordance with theory.
+While each flux tube on a flux surface is unique, several different flux tubes
+in HSX or NCSX can reproduce the zonal flow damping from a flux-surface
+calculation given an adequate parallel extent. The flux-surface or flux-tube
+calculations can accurately reproduce the full-volume long-time residual for
+moderate $k_x$, but the oscillation and damping time scales are longer in local
+representations, particularly for small $k_x$ approaching the system size.",2012.12213v2
+2020-12-31,Damping of slow surface kink modes in solar photospheric waveguides modeled by one-dimensional inhomogeneities,"Given the recent interest in magnetohydrodynamic (MHD) waves in pores and
+sunspot umbrae, we examine the damping of slow surface kink modes (SSKMs) by
+modeling solar photospheric waveguides with a cylindrical inhomogeneity
+comprising a uniform interior, a uniform exterior, and a continuous transition
+layer (TL) in between. Performing an eigen-mode analysis in linear, resistive,
+gravity-free MHD, our approach is idealized in that, among other things, our
+equilibrium is structured only in the radial direction. We can nonetheless
+address two damping mechanisms simultaneously, one being the Ohmic resistivity,
+and the other being the resonant absorption of SSKMs in the cusp and
+Alfv$\acute{\rm e}$n continua. We find that the relative importance of the two
+mechanisms depends sensitively on the magnetic Reynolds number ($R_{\rm m}$).
+Resonant absorption is the sole damping mechanism for realistically large
+values of $R_{\rm m}$, and the cusp resonance in general dominates the
+Alfv$\acute{\rm e}$n one unless the axial wavenumbers are at the lower end of
+the observationally relevant range. We also find that the thin-boundary
+approximation holds only when the TL-width-to-radius ratios are much smaller
+than nominally expected. The Ohmic resistivity is far more important for
+realistically small $R_{\rm m}$. Even in this case, SSKMs are only marginally
+damped, with damping-time-to-period-ratios reaching $\sim 10$ in the parameter
+range we examine.",2012.15426v1
+2021-02-24,Finding the mechanism of wave energy flux damping in solar pores using numerical simulations,"Context. Solar magnetic pores are, due to their concentrated magnetic fields,
+suitable guides for magnetoacoustic waves. Recent observations have shown that
+propagating energy flux in pores is subject to strong damping with height;
+however, the reason is still unclear. Aims. We investigate possible damping
+mechanisms numerically to explain the observations. Methods. We performed 2D
+numerical magnetohydrodynamic (MHD) simulations, starting from an equilibrium
+model of a single pore inspired by the observed properties. Energy was inserted
+into the bottom of the domain via different vertical drivers with a period of
+30s. Simulations were performed with both ideal MHD and non-ideal effects.
+Results. While the analysis of the energy flux for ideal and non-ideal MHD
+simulations with a plane driver cannot reproduce the observed damping, the
+numerically predicted damping for a localized driver closely corresponds with
+the observations. The strong damping in simulations with localized driver was
+caused by two geometric effects, geometric spreading due to diverging field
+lines and lateral wave leakage.",2102.12420v1
+2022-04-08,Damped Strichartz estimates and the incompressible Euler--Maxwell system,"Euler--Maxwell systems describe the dynamics of inviscid plasmas. In this
+work, we consider an incompressible two-dimensional version of such systems and
+prove the existence and uniqueness of global weak solutions, uniformly with
+respect to the speed of light $c\in (c_0,\infty)$, for some threshold value
+$c_0>0$ depending only on the initial data. In particular, the condition
+$c>c_0$ ensures that the velocity of the plasma nowhere exceeds the speed of
+light and allows us to analyze the singular regime $c\to\infty$.
+  The functional setting for the fluid velocity lies in the framework of
+Yudovich's solutions of the two-dimensional Euler equations, whereas the
+analysis of the electromagnetic field hinges upon the refined interactions
+between the damping and dispersive phenomena in Maxwell's equations in the
+whole space. This analysis is enabled by the new development of a robust
+abstract method allowing us to incorporate the damping effect into a variety of
+existing estimates. The use of this method is illustrated by the derivation of
+damped Strichartz estimates (including endpoint cases) for several dispersive
+systems (including the wave and Schr\""odinger equations), as well as damped
+maximal regularity estimates for the heat equation. The ensuing damped
+Strichartz estimates supersede previously existing results on the same systems.",2204.04277v3
+2022-05-11,A new look at the frequency-dependent damping of slow-mode waves in the solar corona,"Being directly observed in the Doppler shift and imaging data and indirectly
+as quasi-periodic pulsations in solar and stellar flares, slow magnetoacoustic
+waves offer an important seismological tool for probing many vital parameters
+of the coronal plasma. A recently understood active nature of the solar corona
+for magnetoacoustic waves, manifested through the phenomenon of wave-induced
+thermal misbalance, led to the identification of new natural mechanisms for the
+interpretation of observed properties of waves. A frequency-dependent damping
+of slow waves in various coronal plasma structures remains an open question, as
+traditional wave damping theories fail to match observations. We demonstrate
+that accounting for the back-reaction caused by thermal misbalance on the wave
+dynamics leads to a modification of the relationship between the damping time
+and oscillation period of standing slow waves, prescribed by the linear theory.
+The modified relationship is not of a power-law form and has the equilibrium
+plasma conditions and properties of the coronal heating/cooling processes as
+free parameters. It is shown to readily explain the observed scaling of the
+damping time with period of standing slow waves in hot coronal loops.
+Functional forms of the unknown coronal heating process, consistent with the
+observed frequency-dependent damping, are seismologically revealed.",2205.05346v1
+2022-12-13,The Effect of Internal Damping on Locomotion in Frictional Environments,"The gaits of undulating animals arise from a complex interaction of their
+central nervous system, muscle, connective tissue, bone, and environment. As a
+simplifying assumption, many previous studies have often assumed that
+sufficient internal force is available to produce observed kinematics, thus not
+focusing on quantifying the interconnection between muscle effort, body shape,
+and external reaction forces. This interplay, however, is critical to
+locomotion performance in crawling animals, especially when accompanied by body
+viscoelasticity. Moreover, in bio-inspired robotic applications, the body's
+internal damping is indeed a parameter that the designer can tune. Still, the
+effect of internal damping is not well understood. This study explores how
+internal damping affects the locomotion performance of a crawler with a
+continuous, visco-elastic, nonlinear beam model. Crawler muscle actuation is
+modeled as a traveling wave of bending moment propagating posteriorly along the
+body. Consistent with the friction properties of the scales of snakes and
+limbless lizards, environmental forces are modeled using anisotropic Coulomb
+friction. It is found that by varying the crawler body's internal damping, the
+crawler's performance can be altered, and distinct gaits could be achieved,
+including changing the net locomotion direction from forward to back. We will
+discuss this forward and backward control and identify the optimal internal
+damping for peak crawling speed.",2212.06290v1
+2023-01-19,Inverse Problems of Identifying the Unknown Transverse Shear Force in the Euler-Bernoulli Beam with Kelvin-Voigt Damping,"In this paper, we study the inverse problems of determining the unknown
+transverse shear force $g(t)$ in a system governed by the damped
+Euler-Bernoulli equation $\rho(x)u_{tt}+\mu(x)u_t+ (r(x)u_{xx})_{xx}+
+(\kappa(x)u_{xxt})_{xx}=0, ~(x,t)\in (0,\ell)\times(0,T],$ subject to the
+boundary conditions $u(0,t) =0$, $u_{x}(0,t)=0$,
+$\left[r(x)u_{xx}+\kappa(x)u_{xxt}\right]_{x=\ell} =0$,
+$-\left[\big(r(x)u_{xx}+\kappa(x)u_{xxt}\big)_{x}\right]_{x=\ell}=g(t)$, $t\in
+[0,T]$, from the measured deflection $\nu(t):=u(\ell,t)$, $t \in [0,T]$, and
+from the bending moment $\omega(t):=-\left(
+r(0)u_{xx}(0,t)+\kappa(0)u_{xxt}(0,t) \right)$, $t \in [0,T]$, where the terms
+$(\kappa(x)u_{xxt})_{xx}$ and $\mu(x)u_t$ account for the Kelvin-Voigt damping
+and external damping, respectively.
+  The main purpose of this study is to analyze the Kelvin-Voigt damping effect
+on determining the unknown transverse shear force (boundary input) through the
+given boundary measurements. The inverse problems are transformed into
+minimization problems for Tikhonov functionals, and it is shown that the
+regularized functionals admit unique solutions for the inverse problems. By
+suitable regularity on the admissible class of shear force $g(t),$ we prove
+that these functionals are Fr\'echet differentiable, and the derivatives are
+expressed through the solutions of corresponding adjoint problems posed with
+measured data as boundary data associated with the direct problem. The
+solvability of these adjoint problems is obtained under the minimal regularity
+of the boundary data $g(t)$, which turns out to be the regularizing effect of
+the Kelvin-Voigt damping in the direct problem.",2301.07931v1
+2023-03-28,Escape Kinetics of an Underdamped Colloidal Particle from a Cavity through Narrow Pores,"It is often desirable to know the controlling mechanism of survival
+probability of nano - or microscale particles in small cavities such as, e.g.,
+confined submicron particles in fiber beds of high-efficiency filter media or
+ions/small molecules in confined cellular structures. Here we address this
+issue based on numerical study of the escape kinetics of inertial Brownian
+colloidal particles from various types of cavities with single and multiple
+pores. We consider both the situations of strong and weak viscous damping. Our
+simulation results show that as long as the thermal length is larger than the
+cavity size the mean exit time remains insensitive to the medium viscous
+damping. On further increasing damping strength, a linear relation between
+escape rate and damping strength emerges gradually. This result is in sharp
+contrast to the energy barrier crossing dynamics where the escape rate exhibits
+a turnover behavior as a function of the damping strength. Moreover, in the
+ballistic regime, the exit rate is directly proportional to the pore width and
+the thermal velocity. All these attributes are insensitive to the cavity as
+well as the pore structures. Further, we show that the effects of pore
+structure variation on the escape kinetics are conspicuously different in the
+low damping regimes compared to the overdamped situation. Apart from direct
+applications in biology and nanotechnology, our simulation results can
+potentially be used to understand diffusion of living or artificial micro/nano
+objects, such as bacteria, virus, Janus Particle etc. where memory effects play
+dictating roles.",2303.16092v1
+2023-06-05,Damping of coronal oscillations in self-consistent 3D radiative MHD simulations of the solar atmosphere,"Oscillations are abundant in the solar corona. Coronal loop oscillations are
+typically studied using highly idealised models of magnetic flux tubes. In
+order to improve our understanding of coronal oscillations, it is necessary to
+consider the effect of realistic magnetic field topology and density
+structuring. We analyse the damping of coronal oscillations using a
+self-consistent 3D radiation-MHD simulation of the solar atmosphere spanning
+from the convection zone into the corona, the associated oscillation
+dissipation and heating, and finally the physical processes responsible for the
+damping and dissipation. The simulated corona formed in such a model does not
+depend on any prior assumptions about the shape of the coronal loops. We find
+that the bundle of magnetic loops shows damped transverse oscillations in
+response to perturbations in two separate instances with oscillation periods of
+177 s and 191 s, velocity amplitudes of 10 km/s and 16 km/s and damping times
+of 176 s and 198 s, respectively. The coronal oscillations lead to the
+development of velocity shear in the simulated corona resulting in the
+formation of vortices seen in the velocity field caused by the Kelvin-Helmholtz
+instability, contributing to the damping and dissipation of the transverse
+oscillations. The oscillation parameters and evolution observed are in line
+with the values typically seen in observations of coronal loop oscillations.
+The dynamic evolution of the coronal loop bundle suggests the models of
+monolithic and static coronal loops with constant lengths might need to be
+re-evaluated by relaxing the assumption of highly idealised waveguides.",2306.02770v1
+2023-08-22,Investigating the characteristic shape and scatter of intergalactic damping wings during reionization,"Ly$\alpha$ damping wings in the spectra of bright objects at high redshift
+are a useful probe of the ionization state of the intergalactic medium during
+the reionization epoch. It has recently been noted that, despite the
+inhomogeneous nature of reionization, these damping wings have a characteristic
+shape which is a strong function of the volume-weighted average neutral
+hydrogen fraction of the intergalactic medium. We present here a closer
+examination of this finding using a simulation of patchy reionization from the
+Sherwood-Relics simulation suite. We show that the characteristic shape and
+scatter of the damping wings are determined by the average neutral hydrogen
+density along the line of sight, weighted by its contribution to the optical
+depth producing the damping wing. We find that there is a redshift dependence
+in the characteristic shape due to the expansion of the Universe. Finally, we
+show that it is possible to differentiate between the shapes of damping wings
+in galaxies and young (or faint) quasars at different points in the
+reionization history at large velocity offsets from the point where the
+transmission first reaches zero.",2308.11709v1
+2023-10-02,Characterizing the Velocity-Space Signature of Electron Landau Damping,"Plasma turbulence plays a critical role in the transport of energy from
+large-scale magnetic fields and plasma flows to small scales, where the
+dissipated turbulent energy ultimately leads to heating of the plasma species.
+A major goal of the broader heliophysics community is to identify the physical
+mechanisms responsible for the dissipation of the turbulence and to quantify
+the consequent rate of plasma heating. One of the mechanisms proposed to damp
+turbulent fluctuations in weakly collisional space and astrophysical plasmas is
+electron Landau damping. The velocity-space signature of electron energization
+by Landau damping can be identified using the recently developed field-particle
+correlation technique. Here, we perform a suite of gyrokinetic turbulence
+simulations with ion plasma beta values of 0.01, 0.1, 1, and 10 and use the
+field-particle correlation technique to characterize the features of the
+velocity-space signatures of electron Landau damping in turbulent plasma
+conditions consistent with those observed in the solar wind and planetary
+magnetospheres. We identify the key features of the velocity-space signatures
+of electron Landau damping as a function of varying plasma \beta_i to provide a
+critical framework for interpreting the results of field-particle correlation
+analysis of in situ spacecraft observations of plasma turbulence.",2310.01242v2
+2024-01-23,Damped kink motions in a system of two solar coronal tubes with elliptic cross-sections,"This study is motivated by observations of coordinated transverse
+displacements in neighboring solar active region loops, addressing specifically
+how the behavior of kink motions in straight two-tube equilibria is impacted by
+tube interactions and tube cross-sectional shapes.We work with linear, ideal,
+pressureless magnetohydrodynamics. Axially standing kink motions are examined
+as an initial value problem for transversely structured equilibria involving
+two identical, field-aligned, density-enhanced tubes with elliptic
+cross-sections (elliptic tubes). Continuously nonuniform layers are implemented
+around both tube boundaries. We numerically follow the system response to
+external velocity drivers, largely focusing on the quasi-mode stage of internal
+flows to derive the pertinent periods and damping times. The periods and
+damping times we derive for two-circular-tube setups justify available modal
+results found with the T-matrix approach. Regardless of cross-sectional shapes,
+our nonuniform layers feature the development of small-scale shears and energy
+accumulation around Alf\'ven resonances, indicative of resonant absorption and
+phase-mixing. As with two-circular-tube systems, our configurational symmetries
+make it still possible to classify lower-order kink motions by the polarization
+and symmetric properties of the internal flows; hence such mode labels as $S_x$
+and $A_x$. However, the periods and damping times for two-elliptic-tube setups
+further depend on cross-sectional aspect ratios, with $A_x$ motions
+occasionally damped less rapidly than $S_x$ motions. We find uncertainties up
+to $\sim 20\%$ ($\sim 50\%$) for the axial Alfven time (the inhomogeneity
+lengthscale) if the periods (damping times) computed for two-elliptic-tube
+setups are seismologically inverted with canonical theories for isolated
+circular tubes.",2401.12885v2
+1995-02-08,The Chemical Evolution of Damped Lyman Alpha Galaxies,"Measurements of element abundances in damped Lyman alpha systems are
+providing new means to investigate the chemical evolution of galaxies,
+particularly at early times. We review progress in this area, concentrating on
+recent efforts to extend the range of existing surveys to both higher and lower
+redshifts.",9502047v1
+1996-01-19,The Chemical Enrichment History of Damped Lyman-alpha Galaxies,"Studies of damped Lyman-alpha absorption systems in quasar spectra are
+yielding very interesting results regarding the chemical evolution of these
+galaxies. We present some preliminary results from such a program.",9601098v1
+1997-01-30,Initial Chemical Enrichment in Galaxies,"We present evidence that damped Lyman-alpha galaxies detected in spectra of
+quasars may not have started forming stars until the redshift z~3. If damped
+Lyman-alpha absorbers are the progenitors of disk galaxies, then the above
+result may indicate that star formation in galactic disks first began at z~3.",9701241v1
+1997-10-24,The N/Si Abundance Ratio in Fifteen Damped Lyman-alpha Galaxies: Implications for the Origin of Nitrogen,"Galactic chemical evolution model calculations indicate that there should be
+considerable scatter in the observed N/O ratios at a fixed metallicity (O/H)
+for galaxies with very low metallicities due to the delayed release of primary
+N from intermediate mass stars relative to that of O from short-lived massive
+stars. Moreover, the scatter should increase progressively toward decreasing
+metallicity. Such effects have not been convincingly demonstrated by
+observations of H II regions in nearby metal-poor galaxies, raising doubts
+about the time-delay model of primary N production. Pettini et al and Lipman et
+al realized the utility of high-redshift damped Lyman-alpha galaxies for
+gaining further insights into the origin of N and discussed abundances in three
+damped Lyman-alpha galaxies. Since abundance measurements for O are generally
+unavailable for damped Lyman-alpha galaxies, they used N/Si or N/S in place of
+N/O under the reasonable assumption that the abundance ratios O/Si and O/S are
+the same as solar in damped Lyman-alpha galaxies. We discuss observations of
+heavy element abundances in 15 high-redshift (z>2) damped Lyman-alpha galaxies,
+many of which have metallicities comparable to or lower than the lowest
+metallicity galaxy known locally (I Zw 18). We find that the N/Si ratios in
+damped Lyman-alpha galaxies exhibit a very large scatter (about 1 dex) at
+[Si/H]~-2 and there is some indication that the scatter increases toward
+decreasing metallicity. Considerations of various sources of uncertainties
+suggest that they are not likely the main causes of the large scatter. These
+results thus provide strong support for the time-delay model of primary N
+production in intermediate mass stars if, indeed, O/Si=solar in damped
+Lyman-alpha galaxies.",9710266v2
+2001-06-05,On Nonlinear Alfvén Waves Generated by Cosmic Ray Streaming Instability,"Nonlinear damping of parallel propagating Alfv\'en waves in high-$\beta$
+plasma is considered. Trapping of thermal ions and Coulomb collisions are taken
+into account. Saturated damping rate is calculated. Applications are made for
+cosmic ray propagation in the Galaxy.",0106078v1
+2001-10-15,The UCSD HIRES/KeckI Damped Lya Abundance Database: II. The Implications,"We present a comprehensive analysis of the damped Lya abundance database
+presented in the first paper of this series. This database provides a
+homogeneous set of abundance measurements for many elements including Si, Cr,
+Ni, Zn, Fe, Al, S, Co, O, and Ar from 38 damped Lya systems with z > 1.5. With
+little exception, these damped Llya systems exhibit very similar relative
+abundances. There is no significant correlation in X/Fe with [Fe/H] metallicity
+and the dispersion in X/Fe is small at all metallicity.
+  We search the database for trends indicative of dust depletion and in a few
+cases find strong evidence. Specifically, we identify a correlation between
+[Si/Ti] and [Zn/Fe] which is unambiguous evidence for depletion.
+  We present a discussion on the nucleosynthetic history of the damped Lya
+systems by focusing on abundance patterns which are minimally affected by dust
+depletion. We find [Si/Fe] -> +0.25 dex as [Zn/Fe] -> 0 and that the [Si/Fe]
+values exhibit a plateau of ~+0.3 dex at [Si/H] < -1.5 dex. Together these
+trends indicate significant alpha-enrichment in the damped Lya systems at low
+metallicity, an interpretation further supported by the observed O/Fe, S/Fe and
+Ar/Fe ratios. We also discuss Fe-peak nucleosynthesis and the odd-even effect.
+  To assess the impact of dust obscuration, we present estimates of the
+dust-to-gas ratios for the damped Lya sightlines and crudely calculate dust
+extinction corrections. The distribution of extinction corrections suggests the
+effects of dust obscuration are minimal and that the population of 'missing'
+damped systems has physical characteristics similar to the observed sample.
+  We update our investigation on the chemical evolution of the early universe
+in neutral gas. [significantly abridged]",0110351v1
+2005-09-05,"Comment on ""Damping of Tensor Modes in Cosmology""","We provide an analytic solution to the short wave length limit of the
+integro-differential equation describing the damping of the tensor modes of
+gravitational waves.",0509096v2
+1997-02-12,Crossover from coherent to incoherent dynamics in damped quantum systems,"The destruction of quantum coherence by environmental influences is
+investigated taking the damped harmonic oscillator and the dissipative
+two-state system as prototypical examples. It is shown that the location of the
+coherent-incoherent transition depends to a large degree on the dynamical
+quantity under consideration.",9702115v1
+1998-06-05,Dielectric formalism and damping of collective modes in trapped Bose-Einstein condensed gases,"We present the general dielectric formalism for Bose-Einstein condensed
+systems in external potential at finite temperatures. On the basis of a model
+arising within this framework as a first approximation in an intermediate
+temperature region for large condensate we calculate the damping of low-energy
+excitations in the collisionless regime.",9806079v1
+1999-05-27,Do correlations create an energy gap in electronic bilayers? Critical analysis of different approaches,"This paper investigates the effect of correlations in electronic bilayers on
+the longitudinal collective mode structure. We employ the dielectric
+permeability constructed by means of the classical theory of moments. It is
+shown that the neglection of damping processes overestimates the role of
+correlations. We conclude that the correct account of damping processes leads
+to an absence of an energy gap.",9905405v1
+1999-11-16,Damping of low-energy excitations of a Bose-condensed gas in the hydrodynamic regime,"We develop a theory to describe the damping of elementary excitations of a
+Bose-condensed gas in the hydrodynamic regime for the thermal cloud. We discuss
+second sound in a spatially homogeneous gas and the lowest excitations of a
+trapped condensate.",9911238v2
+2002-04-18,"Faraday patterns in Bose-Einstein condensates. Amplitude equation for rolls in the parametrically driven, damped Gross-Pitaevskii equation","The parametrically driven, damped Gross-Pitaevskii equation, which models
+Bose-Einstein condensates in which the interatomic s-wave scattering length is
+modulated in time, is shown to support spatially modulated states in the form
+of rolls. A Landau equation with broken phase symmetry is derived, which
+governs the dynamics of the roll amplitude.",0204406v1
+2002-11-14,Sound damping in ferrofluids: Magnetically enhanced compressional viscosity,"The damping of sound waves in magnetized ferrofluids is investigated and
+shown to be considerably higher than in the non-magnetized case. This fact may
+be interpreted as a field-enhanced, effective compressional viscosity -- in
+analogy to the ubiquitous field-enhanced shear viscosity that is known to be
+the reason for many unusual behavior of ferrofluids under shear.",0211297v1
+2003-10-23,Input and output in damped quantum systems III: Formulation of damped systems driven by Fermion fields,"A comprehensive input-output theory is developed for Fermionic input fields.
+Quantum stochastic differential equations are developed in both the Ito and
+Stratonovich forms. The major technical issue is the development of a formalism
+which takes account of anticommutation relations between the Fermionic driving
+field and those system operators which can change the number of Fermions within
+the system.",0310542v1
+2004-01-12,Nonexponential motional damping of impurity atoms in Bose-Einstein condensates,"We demonstrate that the damping of the motion of an impurity atom injected at
+a supercritical velocity into a Bose-Einstein condensate can exhibit
+appreciable deviation from the exponential law on time scales of $10^{-5}$ s.",0401172v1
+2005-02-21,Two Transitions in the Damping of a Unitary Fermi Gas,"We measure the temperature dependence of the radial breathing mode in an
+optically trapped, strongly-interacting Fermi gas of $^6$Li, just above the
+center of a broad Feshbach resonance. The frequency remains close to the
+unitary hydrodynamic value, while the damping rate reveals transitions at two
+well-separated temperatures, consistent with the existence of atom pairs above
+a superfluid transition.",0502507v1
+1994-07-04,Cat States and Single Runs for the Damped Harmonic Oscillator,"We discuss the fate of initial states of the cat type for the damped harmonic
+oscillator, mostly employing a linear version of the stochastic Schr\""odinger
+equation. We also comment on how such cat states might be prepared and on the
+relation of single realizations of the noise to single runs of experiments.",9407001v1
+2000-10-27,Damping and the Hartree Ensemble Approximation,"We study a Hartree ensemble approximation for real-time dynamics in the toy
+model of 1+1 dimensional scalar field theory. Damping behavior seen in
+numerical simulations is compared with analytical predictions based on
+perturbation theory in the original (non-Hartree-approximated) model.",0010054v1
+1995-03-21,APPLICATIONS OF HIGH-TEMPERATURE FIELD THEORY TO HEAVY-ION COLLISIONS,"A recent development in finite temperature field theory, the so-called
+Braaten-Pisarski method, and its application to properties of a quark-gluon
+plasma, possibly formed in relativistic heavy ion collisions, are reviewed. In
+particular parton damping rates, the energy loss of energetic partons,
+thermalization times, viscosity, and production and damping rates of hard
+photons are discussed.",9503400v1
+1996-03-19,Damping Rate and Lyapunov Exponent of a Higgs Field at High Temperature,"The damping rate of a Higgs field at zero momentum is calculated using the
+Braaten-Pisarski method and compared to the Lyapunov exponent of the classical
+SU(2) Yang-Mills Higgs system.",9603339v1
+1997-04-30,Comments on the Erhan-Schlein model of damping the pomeron flux at small x-pomeron,"We explore the theoretical and experimental consequences of a model proposed
+by Samim Erhan and Peter Schlein for unitarizing the diffractive amplitude by
+damping the pomeron flux at small x-pomeron and conclude that the model is
+unphysical and contradicts well established experimental data.",9704454v1
+1998-03-26,The Nonlinear Spatial Damping Rate in QGP,"The derivative expansion method has been used to solve the semiclassical
+kinetic equations of quark-gluon plasma (QGP). The nonlinear spatial damping
+rate, the imaginary part of the wave vector, for the longitudinal secondary
+color waves in the long wavelength limit has been calculated numerically.",9803455v1
+2006-07-27,Long-Time Asymptotic Behavior of Dissipative Boussinesq System,"In this paper, we study various dissipative mechanics associated with the
+Boussinesq systems which model two-dimensional small amplitude long wavelength
+water waves. We will show that the decay rate for the damped one-directional
+model equations, such as the KdV and BBM equations, holds for some of the
+damped Boussinesq systems which model two-directional waves.",0607708v1
+2006-12-27,Stochastic inertial manifolds for damped wave equations,"In this paper, stochastic inertial manifold for damped wave equations
+subjected to additive white noise is constructed by the Lyapunov-Perron method.
+It is proved that when the intensity of noise tends to zero the stochastic
+inertial manifold converges to its deterministic counterpart almost surely.",0612774v1
+2007-01-19,On the Domain of Analyticity and Small Scales for the Solutions of the Damped-driven 2D Navier-Stokes Equations,"We obtain a logarithmically sharp estimate for the space-analyticity radius
+of the solutions of the damped-driven 2D Navier-Stokes equations with periodic
+boundary conditions and relate this to the small scales in this system. This
+system is inspired by the Stommel--Charney barotropic ocean circulation model.",0701530v1
+2002-09-04,Wigner function for damped systems,"Both classical and quantum damped systems give rise to complex spectra and
+corresponding resonant states. We investigate how resonant states, which do not
+belong to the Hilbert space, fit the phase space formulation of quantum
+mechanics. It turns out that one may construct out of a pair of resonant states
+an analog of the stationary Wigner function.",0209008v1
+2004-12-14,Two-Ion Dusty Plasma Waves and Landau Damping,"The paper analyses the properties of dusty plasmas in the extreme conditions
+when the free electrons are absent. The nonlinear Korteveg de Vries equation
+with a nonlocal (integral) term in a small parameter approximation is derived.
+The conditions are determined when the integral term is essential hence the
+Landau damping of two-ion-dusty plasma waves is substantial.",0412033v1
+2002-10-16,Dependence of Nuclear Level Density on Vibrational State Damping,"The response function approach is proposed to include vibrational state in
+calculation of level density. The calculations show rather strong dependence of
+level density on the relaxation times of collective state damping.",0210048v1
+1999-02-09,One-Dimensional Motion of Sommerfeld Sphere in Potential Hole in Classical Electrodynamics: Inside the Hole,"Equation of motion of Sommerfeld sphere in the one-dimensional potential
+hole, produced by two equal charges on some distance from each other, is
+numerically investigated. Two types of solutions are found: (i) damping
+oscillations, (ii) oscillations without damping (radiationless motion).
+Solutions with growing amplitude (""climbing-up-the-wall solution"") for chosen
+initial conditions were not founded.",9902018v3
+2000-03-23,The Hawking-Unruh Temperature and Damping in a Linear Focusing Channel,"The Hawking-Unruh effective temperature, hbar a* / 2 pi c k, due to quantum
+fluctuations in the radiation of an accelerated charged-particle beam can be
+used to show that transverse oscillations of the beam in a practical linear
+focusing channel damp to the quantum-mechanical limit. A comparison is made
+between this behavior and that of beams in a wiggler.",0003061v1
+2003-06-17,Ruchhardt Oscillator Decay- Thermodynamic basis for Hysteretic Damping,"Using thermodynamic arguments based on the ideal gas law, it is shown that
+hysteretic (also called structural) damping is the natural form of energy
+dissipation for this classic oscillator that is used to measure the ratio of
+heat capacities for a gas.",0306136v1
+2005-08-25,Rutherford scattering with radiation damping,"We study the effect of radiation damping on the classical scattering of
+charged particles. Using a perturbation method based on the Runge-Lenz vector,
+we calculate radiative corrections to the Rutherford cross section, and the
+corresponding energy and angular momentum losses.",0508186v2
+2006-01-18,Expressions for frictional and conservative force combinations within the dissipative Lagrange-Hamilton formalism,"Dissipative Lagrangians and Hamiltonians having Coulomb, viscous and
+quadratic damping,together with gravitational and elastic terms are presented
+for a formalism that preserves the Hamiltonian as a constant of the motion.
+Their derivations are also shown. The resulting L's and H's may prove useful in
+exploring new types of damped quantum systems.",0601133v1
+1997-03-27,Macroscopic quantum damping in SQUID rings,"The measurement process is introduced in the dynamics of Josephson devices
+exhibiting quantum behaviour in a macroscopic degree of freedom. The
+measurement is shown to give rise to a dynamical damping mechanism whose
+experimental observability could be relevant to understand decoherence in
+macroscopic quantum systems.",9703052v1
+2005-07-19,Radiation reaction and quantum damped harmonic oscillator,"By taking a Klein-Gordon field as the environment of an harmonic oscillator
+and using a new method for dealing with quantum dissipative systems (minimal
+coupling method), the quantum dynamics and radiation reaction for a quantum
+damped harmonic oscillator investigated. Applying perturbation method, some
+transition probabilities indicating the way energy flows between oscillator,
+reservoir and quantum vacuum, obtained",0507179v1
+2005-08-18,Density operator and entropy of the damped quantum harmonic oscillator,"The expression for the density operator of the damped harmonic oscillator is
+derived from the master equation in the framework of the Lindblad theory for
+open quantum systems. Then the von Neumann entropy and effective temperature of
+the system are obtained. The entropy for a state characterized by a Wigner
+distribution function which is Gaussian in form is found to depend only on the
+variance of the distribution function.",0508141v1
+2006-03-03,On the damping of the angular momentum of three harmonic oscillators,"In the frame of the Lindblad theory of open quantum systems, the system of
+three uncoupled harmonic oscillators with opening operators linear in the
+coordinates and momenta of the considered system is analyzed. The damping of
+the angular momentum and of its projection is obtained.",0603029v1
+2006-10-10,Simultaneous amplification and non-symmetric amplitude damping of two-mode Gaussian state,"The evolution of two-mode Gaussian state under symmetric amplification,
+non-symmetric damping and thermal noise is studied. The time dependent solution
+of the state characteristic function is obtained. The separability criterions
+are given for the final state of weak amplification as well as strong
+amplification.",0610070v1
+2007-10-13,The separability of tripartite Gaussian state with amplification and amplitude damping,"Tripartite three mode Gaussian state undergoes parametric amplification and
+amplitude damping as well as thermal noise is studied. In the case of a state
+totally symmetrically interacting with the environment, the time dependent
+correlation matrix of the state in evolution is given. The conditions for fully
+separability and fully entanglement of the final tripartite three mode Gaussian
+state are worked out.",0710.2570v1
+2007-12-16,Nonadditive quantum error correcting codes adapted to the ampltitude damping channel,"A family of high rate quantum error correcting codes adapted to the amplitude
+damping channel is presented. These codes are nonadditive and exploit
+self-complementarity structure to correct all first-order errors. Their rates
+can be higher than 1/2. The recovery operations of these codes can be generated
+by a simple algorithm and have a projection nature, which makes them
+potentially easy to implement.",0712.2586v1
+2007-12-22,Chaos in an intermittently driven damped oscillator,"We observe chaotic dynamics in a damped linear oscillator, which is driven
+only at certain regions of phase space. Both deterministic and random drives
+are studied. The dynamics is characterized using standard techniques of
+nonlinear dynamics. Interchanging roles of determinism and stochasticity is
+also considered.",0712.3827v2
+2008-03-01,Well-posedness of the IBVP for 2-D Euler Equations with Damping,"In this paper we focus on the initial-boundary value problem of the 2-D
+isentropic Euler equations with damping. We prove the global-in-time existence
+of classical solution to the initial-boundary value problem by the method of
+energy estimates.",0803.0039v1
+2008-03-27,Shear viscosity of degenerate electron matter,"We calculate the partial electron shear viscosity $\eta_{ee}$ limited by
+electron-electron collisions in a strongly degenerate electron gas taking into
+account the Landau damping of transverse plasmons. The Landau damping strongly
+suppresses $\eta_{ee}$ in the domain of ultrarelativistic degenerate electrons
+and modifies its %asymptotic temperature behavior. The efficiency of the
+electron shear viscosity in the cores of white dwarfs and envelopes of neutron
+stars is analyzed.",0803.3893v1
+2008-04-09,Stationary Oscillations in a Damped Wave Equation from Isospectral Bessel Functions,"Using the isospectral partners of the Bessel functions derived by Reyes et
+al., we find, on one hand, that these functions show non-typical supersymmetric
+(SUSY) behavior and, on the other, that the isospectral partner of the
+classical wave equation is equivalent to that of a damped system whose
+oscillations do not vanish in time, but show a non-harmonic shape.",0804.1510v1
+2008-06-03,Simulation study of fast ion instability in the ILC damping ring and PETRA III,"The fast ion instability is simulated in different gas pressures and fill
+patterns for the damping ring of the International Linear Collider (ILC) and
+PETRA III respectively. Beam size variation due to beta function and dispersion
+function change is taken into account. Feedback is also applied in the
+simulation.",0806.0529v1
+2008-08-01,Damped wave equations with dynamic boundary conditions,"We discuss several classes of linear second order initial-boundary value
+problems, where damping terms appear in the main wave equation as well as in
+the dynamic boundary condition. We investigate their well-posedness and
+describe some qualitative properties of their solutions, including boundedness,
+stability, or almost periodicity. In particular, we are able to characterize
+the analyticity of certain $C_0$-semigroups associated to such problems.
+Applications to several problems on domains and networks are shown.",0808.0213v1
+2008-12-17,The damping of gravitational waves in dust,"We examine a simple model of interaction of gravitational waves with matter
+(primarily represented by dust). The aim is to investigate a possible damping
+effect on the intensity of gravitational wave when passing through media. This
+might be important for gravitational wave astronomy when the sources are
+obscured by dust or molecular clouds.",0812.3336v1
+2009-05-24,Computer assisted proof of the existence of homoclinic tangency for the Henon map and for the forced-damped pendulum,"We present a topological method for the efficient computer assisted
+verification of the existence of the homoclinic tangency which unfolds
+generically in a one-parameter family of planar maps. The method has been
+applied to the Henon map and the forced damped pendulum ODE.",0905.3924v1
+2009-08-15,"Antigravitation, Dark Energy, Dark Matter - Alternative Solution","Collisional damping of gravitational waves in the Newtonian matter is
+investigated. The generalized theory of Landau damping is applied to the
+gravitational physical systems in the context of the plasma gravitational
+analogy.",0908.2180v3
+2009-08-31,A comment about the existence of a weak solution for a non linear wave equation damped propagation,"We give a proof for the existence of a weak solution on the initial-value
+problem of a non-linear damped propagation",0909.0052v2
+2009-09-15,Quantum Parrondo's games under decoherence,"We study the effect of quantum noise on history dependent quantum Parrondo's
+games by taking into account different noise channels. Our calculations show
+that entanglement can play a crucial role in quantum Parrondo's games. It is
+seen that for the maximally entangled initial state in the presence of
+decoherence, the quantum phases strongly influence the payoffs for various
+sequences of the game. The effect of amplitude damping channel leads to winning
+payoffs. Whereas the depolarizing and phase damping channels lead to the losing
+payoffs. In case of amplitude damping channel, the payoffs are enhanced in the
+presence of decoherence for the sequence AAB. This is because the quantum
+phases interfere constructively which leads to the quantum enhancement of the
+payoffs in comparison to the undecohered case. It is also seen that the quantum
+phase angles damp the payoffs significantly in the presence of decoherence.
+Furthermore, it is seen that for multiple games of sequence AAB, under the
+influence of amplitude damping channel, the game still remains a winning game.
+However, the quantum enhancement reduces in comparison to the single game of
+sequence AAB because of the destructive interference of phase dependent terms.
+In case of depolarizing channel, the game becomes a loosing game. It is seen
+that for the game sequence B the game is loosing one and the behavior of
+sequences B and BB is similar for amplitude damping and depolarizing channels.
+In addition, the repeated games of A are only influenced by the amplitude
+damping channel and the game remains a losing game. Furthermore, it is also
+seen that for any sequence when played in series, the phase damping channel
+does not influence the game.",0909.2897v2
+2009-10-01,Global attractor for weakly damped Nonlinear Schrödinger equations in $L^2(\R)$,"We prove that the weakly damped nonlinear Schr\""odinger flow in
+$L^2(\mathbb{R})$ provides a dynamical system which possesses a global
+attractor. The proof relies on the continuity of the Schr\""odinger flow for the
+weak topology in $L^2(\R)$.",0910.0172v1
+2009-12-11,"Waves, damped wave and observation","We consider the wave equation in a bounded domain (eventually convex). Two
+kinds of inequality are described when occurs trapped ray. Applications to
+control theory are given. First, we link such kind of estimate with the damped
+wave equation and its decay rate. Next, we describe the design of an
+approximate control function by an iterative time reversal method.",0912.2202v1
+2010-01-01,Exponential Energy Decay for Damped Klein-Gordon Equation with Nonlinearities of Arbitrary Growth,"We derive a uniform exponential decay of the total energy for the nonlinear
+Klein-Gordon equation with a damping around spatial infinity in the whole space
+or in the exterior of a star shaped obstacle.",1001.0209v1
+2010-03-10,"Covariant Constitutive Relations, Landau Damping and Non-stationary Inhomogeneous Plasmas","Models of covariant linear electromagnetic constitutive relations are
+formulated that have wide applicability to the computation of susceptibility
+tensors for dispersive and inhomogeneous media. A perturbative framework is
+used to derive a linear constitutive relation for a globally neutral plasma
+enabling one to describe in this context a generalized Landau damping mechanism
+for non-stationary inhomogeneous plasma states.",1003.2062v1
+2010-03-28,Damped wave dynamics for a complex Ginzburg-Landau equation with low dissipation,"We consider a complex Ginzburg-Landau equation, corresponding to a
+Gross-Pitaevskii equation with a small dissipation term. We study an asymptotic
+regime for long-wave perturbations of constant maps of modulus one. We show
+that such solutions never vanish and we derive a damped wave dynamics for the
+perturbation.",1003.5375v1
+2010-06-16,Hysteresis effects in Bose-Einstein condensates,"Here, we consider damped two-components Bose-Einstein condensates with
+many-body interactions. We show that, when the external trapping potential has
+a double-well shape and when the nonlinear coupling factors are modulated in
+time, hysteresis effects may appear under some circumstances. Such hysteresis
+phenomena are a result of the joint contribution between the appearance of
+saddle node bifurcations and damping effect.",1006.3240v1
+2010-09-25,Different Network Topologies for Distributed Electric Damping of Beam Vibrations,"In this work passive electric damping of structural vibrations by distributed
+piezoelectric transducers and electric networks is analyzed. Different
+distributed electric controllers are examined as finite degrees of freedom
+systems and their performances are compared. Modal reduction is used to
+optimize the electric parameters",1009.5001v1
+2010-12-27,The Relativistic kinetics of gravitational waves collisional damping in hot Universe,"The article is a translation of authors paper printed earlier in the
+inaccessible edition and summarizing the results of research of gravitational
+waves damping problem in the cosmologic plasma due to the different
+interactions of elementary particles.",1012.5582v1
+2011-01-14,Blowup for the Damped $L^{2}$-Critical Nonlinear Schrödinger Equation,"We consider the Cauchy problem for the $L^{2}$-critical damped nonlinear
+Schr\""odinger equation. We prove existence and stability of finite time blowup
+dynamics with the log-log blow-up speed for $\|\nabla u(t)\|_{L^2}$.",1101.2763v3
+2011-02-05,Partial regularity of weak solutions of the viscoelastic Navier-Stokes equations with damping,"We prove an analog of the Caffarelli-Kohn-Nirenberg theorem for weak
+solutions of a system of PDE that model a viscoelastic fluid in the presence of
+an energy damping mechanism. The system was recently introduced as a possible
+method of establishing the global in time existence of weak solutions of the
+well known Oldroyd system.",1102.1112v1
+2011-02-21,The One Dimensional Damped Forced Harmonic Oscillator Revisited,"In this paper we give a general solution to the problem of the damped
+harmonic oscillator under the influence of an arbitrary time-dependent external
+force. We employ simple methods accessible for beginners and useful for
+undergraduate students and professors in an introductory course of mechanics.",1102.4112v1
+2011-03-18,"Soliton complexity in the damped-driven nonlinear Schrödinger equation: stationary, periodic, quasiperiodic complexes","Stationary and oscillatory bound states, or complexes, of the damped-driven
+solitons are numerically path-followed in the parameter space. We compile a
+chart of the two-soliton attractors, complementing the one-soliton attractor
+chart.",1103.3607v1
+2011-09-27,Exponential energy decay of solutions for a system of viscoelastic wave equations of Kirchhoff type with strong damping,"The initial boundary value problem for a system of viscoelastic wave
+equations of Kirchhoff type with strong damping is considered. We prove that,
+under suitable assumptions on relaxation functions and certain initial data,
+the decay rate of the solutions energy is exponential.",1109.5921v1
+2011-11-20,Null controllability of the structurally damped wave equation with moving point control,"We investigate the internal controllability of the wave equation with
+structural damping on the one dimensional torus. We assume that the control is
+acting on a moving point or on a moving small interval with a constant
+velocity. We prove that the null controllability holds in some suitable Sobolev
+space and after a fixed positive time independent of the initial conditions.",1111.4655v1
+2011-12-04,On the Apparent Superluminal Motion of a Damped Gaussian Pulse,"Alicki has demonstrated that a travelling Gaussian pulse subject to damping
+is indistinguishable from an undamped pulse moving with greater speed; such an
+effect could create the illusion of a pulse moving faster than light. In this
+note, an alternative derivation of the same result is presented. However, it is
+unlikely that this particular illusion could explain the superluminal
+neutrino-velocities reported by OPERA.",1112.1324v1
+2011-12-28,Photon Damping in One-Loop HTL Perturbation Theory,"We determine the damping rates of slow-moving photons in next-to-leading
+order hard-thermal-loop perturbation of massless QED. We find both longitudinal
+and transverse rates finite, positive, and equal at zero momentum. Various
+divergences, light-cone and at specific momenta, but not infrared, appear and
+cancel systematically.",1112.6065v2
+2012-04-06,Late time evolution of the gravitational wave damping in the early Universe,"An analytical solution for time evolution of the gravitational wave damping
+in the early Universe due to freely streaming neutrinos is found in the late
+time regime. The solution is represented by a convergent series of spherical
+Bessel functions of even order and was possible with the help of a new compact
+formula for the convolution of spherical Bessel functions of integer order.",1204.1384v2
+2012-05-30,Beam Dynamics Studies for the CLIC Main Linac,"The implications of long-range wakefields on the beam quality are
+investigated through a detailed beam dynamics study. Injection offsets are
+considered and the resulting emittance dilution recorded, including systematic
+sources of error. These simulations have been conducted for damped and detuned
+structures (DDS) and for waveguide damped structures-both for the CLIC
+collider.",1205.6623v2
+2012-07-31,Energy decay rates for solutions of the wave equations with nonlinear damping in exterior domain,"In this paper we study the behaviors of the energy of solutions of the wave
+equations with localized nonlinear damping in exterior domains.",1207.7336v3
+2012-11-02,A modified test function method for damped waves,"In this paper we use a modified test function method to derive nonexistence
+results for the semilinear wave equation with time-dependent speed and damping.
+The obtained critical exponent is the same exponent of some recent results on
+global existence of small data solution.",1211.0453v1
+2012-12-15,Damping and Pseudo-fermions,"After a short abstract introduction on the time evolution driven by non
+self-adjoint hamiltonians, we show how the recently introduced concept of {\em
+pseudo-fermion} can be used in the description of damping in finite dimensional
+quantum systems, and we compare the results deduced adopting the Schr\""odinger
+and the Heisenberg representations.",1212.3663v1
+2013-01-14,On estimating the output entropy of a tensor product of the quantum phase-damping channel with an arbitrary channel,"We obtained the estimation from below for the output entropy of a tensor
+product of the quantum phase-damping channel with an arbitrary channel. It is
+shown that from this estimation immediately follows that the strong
+superadditivity of the output entropy holds for this channel as well as for the
+quantum depolarizing channel.",1301.2886v1
+2013-06-10,Smooth attractors for the quintic wave equations with fractional damping,"Dissipative wave equations with critical quintic nonlinearity and damping
+term involving the fractional Laplacian are considered. The additional
+regularity of energy solutions is established by constructing the new
+Lyapunov-type functional and based on this, the global well-posedness and
+dissipativity of the energy solutions as well as the existence of a smooth
+global and exponential attractors of finite Hausdorff and fractal dimension is
+verified.",1306.2294v1
+2013-07-20,Entanglement-assisted capacities of time-correlated amplitude-damping channel,"We calculate the information capacities of a time-correlated
+amplitude-damping channel, provided the sender and receiver share prior
+entanglement. Our analytical results show that the noisy channel with zero
+capacity can transmit information if it has finite memory. The capacities
+increase as the memory increases attaining maximum value for perfect memory
+channel.",1307.5403v1
+2013-07-23,Comment on Damping Force in the Transit-time Method of Optical Stochastic Cooling,"In this brief report we pointed at mistake in paper A. Zholents, Damping
+Force in the Transit-Time Method of Optical Stochastic Cooling, PRLST. Mar 1,
+2012. 2 pp. Published in Phys.Rev.ST Accel. Beams 15 (2012) 032801.",1307.6185v1
+2013-08-23,Stability results for second-order evolution equations with switching time-delay,"We consider second-order evolution equations in an abstract setting with
+intermittently delayed/ not-delayed damping. We give sufficient conditions for
+asymptotic and exponential stability, improving and generalising our previous
+results from [19]. In particular, under suitable conditions, we can consider
+unbounded damping operators. Some concrete examples are finally presented.",1308.5100v1
+2013-09-10,Convergence of global solutions for some classes of nonlinear damped wave equations,"We consider the asymptotic behavior of the soltion to the wave equation with
+time-dependent damping and analytic nonlinearity. Our main goal is to prove the
+convergence of a global solution to an equilibrium as time goes to infinity by
+means of a suitable Lojasiewicz-Simon type inequality.",1309.2364v1
+2013-09-13,On diffusion phenomena for the linear wave equation with space-dependent damping,"In this paper, we prove the diffusion phenomenon for the linear wave equation
+with space-dependent damping. We prove that the asymptotic profile of the
+solution is given by a solution of the corresponding heat equation in the
+$L^2$-sense.",1309.3377v1
+2013-09-19,Compressible Euler equation with damping on Torus in arbitrary dimensions,"We study the exponential stability of constant steady state of isentropic
+compressible Euler equation with damping on $\mathbb T^n$. The local existence
+of solutions is based on semigroup theory and some commutator estimates. We
+propose a new method instead of energy estimates to study the stability, which
+works equally well for any spatial dimensions.",1309.5059v3
+2013-10-28,Large deviations for a damped telegraph process,"In this paper we consider a slight generalization of the damped telegraph
+process in Di Crescenzo and Martinucci (2010). We prove a large deviation
+principle for this process and an asymptotic result for its level crossing
+probabilities (as the level goes to infinity). Finally we compare our results
+with the analogous well-known results for the standard telegraph process.",1310.7332v1
+2013-10-29,Blow-up for the wave equation with nonlinear source and boundary damping terms,"The paper deals with blow--up for the solutions of wave equation with
+nonlinear source and nonlinear boudary damping terms, posed in a bounded and
+regular domain. The initial data are posed in the energy space. The aim of the
+paper is to improve previous blow-up results concerning the problem.",1310.7734v1
+2013-11-24,Global small solution to the 2D MHD system with a velocity damping term,"This paper studies the global well-posedness of the incompressible
+magnetohydrodynamic (MHD) system with a velocity damping term. We establish the
+global existence and uniqueness of smooth solutions when the initial data is
+close to an equilibrium state. In addition, explicit large-time decay rates for
+various Sobolev norms of the solutions are also given.",1311.6185v1
+2014-08-25,Asymptotic behavior of global entropy solutions for nonstrictly hyperbolic systems with linear damping,"In this paper we investigate the large time behavior of the global weak
+entropy solutions to the symmetric Keyftiz-Kranzer system with linear damping.
+It is proved that as t tends to infinite the entropy solutions tend to zero in
+the L p norm",1408.5856v1
+2015-02-02,"Spontaneous toroidal rotation, anomalous radial particle flux, and the electron-ion asymmetric anomalous viscous damping","AA spontaneous toroidal rotation due to the electron-ion asymmetric anomalous
+viscous damping and the turbulent radial particle flux has been found, which
+explains the experimental observation of the anomalous toroidal momentum source
+in the edge of a tokamak plasma.",1502.00499v3
+2015-03-06,Concentration Of Laplace Eigenfunctions And Stabilization Of Weakly Damped Wave Equation,"- In this article, we prove some universal bounds on the speed of
+concentration on small (frequency-dependent) neighborhoods of submanifolds of L
+2-norms of quasi modes for Laplace operators on compact manifolds. We deduce
+new results on the rate of decay of weakly damped wave equations.
+R{\'e}sum{\'e}.",1503.02058v1
+2015-03-11,Upper bounds for the attractor dimension of damped Navier-Stokes equations in $\mathbb R^2$,"We consider finite energy solutions for the damped and driven two-dimensional
+Navier--Stokes equations in the plane and show that the corresponding dynamical
+system possesses a global attractor. We obtain upper bounds for its fractal
+dimension when the forcing term belongs to the whole scale of homogeneous
+Sobolev spaces from -1 to 1",1503.03415v1
+2015-03-18,Laplace Eigenfunctions And Damped Wave Equation Ii: Product Manifolds,"- The purpose of this article is to study possible concentrations of
+eigenfunc-tions of Laplace operators (or more generally quasi-modes) on product
+manifolds. We show that the approach of the first author and Zworski [10, 11]
+applies (modulo rescalling) and deduce new stabilization results for weakly
+damped wave equations which extend to product manifolds previous results by
+Leautaud-Lerner [12] obtained for products of tori.",1503.05513v1
+2016-01-13,Non uniform decay of the energy of some dissipative evolution systems,"In this paper we consider second order evolution equations with bounded
+damping. We give a characterization of a non uniform decay for the damped
+problem using a kind of observability estimate for the associated undamped
+problem.",1601.03373v1
+2016-01-27,Forward self-similar solutions to the viscoelastic Navier-Stokes equation with damping,"Motivated by \cite{JS}, we prove that there exists a global, forward
+self-similar solution to the viscoelastic Navier-Stokes equation with damping,
+that is smooth for $t>0$, for any initial data that is homogeneous of degree
+$-1$.",1601.07478v1
+2016-03-14,Phase speed and frequency-dependent damping of longitudinal intensity oscillations in coronal loop structures observed with AIA/SDO,"Longitudinal intensity oscillations along coronal loops that are interpreted
+as signatures of magneto-acoustic waves are observed frequently in different
+coronal structures. The aim of this paper is to estimate the physical
+parameters of the slow waves and the quantitative dependence of these
+parameters on their frequencies in the solar corona loops that are situated
+above active regions with the Atmospheric Imaging Assembly (AIA) onboard Solar
+Dynamic Observatory (SDO). The observed data on 2012-Feb-12, consisting of 300
+images with an interval of 24 seconds in the 171 $\rm{\AA}$ and 193 $\rm{\AA}$
+passbands is analyzed for evidence of propagating features as slow waves along
+the loop structures. Signatures of longitudinal intensity oscillations that are
+damped rapidly as they travel along the loop structures were found, with
+periods in the range of a few minutes to few tens of minutes. Also, the
+projected (apparent) phase speeds, projected damping lengths, damping times and
+damping qualities of filtered intensities centred on the dominant frequencies
+are measured in the range of $\rm{C_s}\simeq 38-79~ \rm {km~s^{-1}}$,
+$\rm{L_d}\simeq 23-68 ~\rm{Mm }$, $\rm{\tau_d}\simeq 7- 21 ~\rm {min}$ and
+$\rm{\tau_d/P}\simeq 0.34- 0.77$, respectively. The theoretical and
+observational results of this study indicate that the damping times and damping
+lengths increase with increasing the oscillation periods, and are highly
+sensitive function of oscillation period, but the projected speeds and the
+damping qualities are not very sensitive to the oscillation periods.
+Furthermore, the magnitude values of physical parameters are in good agreement
+with the prediction of the theoretical dispersion relations of high-frequency
+MHD waves ($>1.1~ \rm{mHz}$) in a coronal plasma with electron number density
+in the range of $\rm{n_e}\simeq 10^{7} - 10^{12} ~\rm{cm^{-3}}$.",1603.04207v1
+2016-04-27,Critical exponent for nonlinear wave equations with frictional and viscoelastic damping terms,"In this paper, we study the Cauchy problem for a nonlinear wave equation with
+frictional and viscoelastic damping terms. Our aim is to obtain the threshold,
+to classify the global existence of solution for small data or the finite time
+blow-up pf the solution, with respect to the growth order of the nonlinearity.",1604.08265v1
+2016-05-19,On circular flows: linear stability and damping,"In this article we establish linear inviscid damping with optimal decay rates
+around 2D Taylor-Couette flow and similar monotone flows in an annular domain
+$B_{r_{2}}(0) \setminus B_{r_{1}}(0) \subset \mathbb{R}^{2}$. Following recent
+results by Wei, Zhang and Zhao, we establish stability in weighted norms, which
+allow for a singularity formation at the boundary, and additional provide a
+description of the blow-up behavior.",1605.05959v1
+2016-08-04,Resonance Damping of the THz-frequency Transverse Acoustic Phonon in the Relaxor Ferroelectric KTa1-xNbxO3,"The damping ($\Gamma_a$) of the transverse acoustic (TA) phonon in single
+crystals of the relaxor $KTa_{1-x}Nb_xO_3$ with x=0.15-0.17 was studied by
+means of high resolution inelastic cold neutron scattering near the (200) B.Z.
+point where diffuse scattering is absent, although it is present near (110). In
+a wide range of temperatures centered on the phase transition, T=195K-108K, the
+TA phonon width (damping) exhibits a step increase around momentum q=0.07, goes
+through a shallow maximum at q=0.09-0.12 and remains high up to the highest
+momentum studied of q=0.16. These experimental results are explained in terms
+of a resonant interaction between the TA phonon and the collective or
+correlated reorientation through tunneling of the off-center Nb+5 ions. The
+observed TA damping is successfully reproduced in a simple model that includes
+an interaction between the TA phonon and a dispersionless localized mode (LM)
+with frequency $\omega_L$ and damping $\Gamma_L$ ($\Gamma_L < \omega_L$),
+itself coupled to the transverse optic (TO) mode. Maximum damping of the TA
+phonon occurs when its frequency $\omega_a \approx{\omega_L}$. $\omega_L$ and
+$\Gamma_L$ are moderately dependent on temperature but the oscillator strength,
+$M_2$, of the resonant damping exhibits a strong maximum in the range
+$T\sim{150 K-120 K}$ in which neutron diffuse scattering near the (110) B.Z.
+point is also maximum and the dielectric susceptibility exhibits the relaxor
+behavior. The maximum value of M appears to be due to the increasing number of
+polar nanodomains. In support of the proposed model, the observed value of
+$\omega_L$ is found to be similar to the estimate previously obtained by
+Girshberg and Yacoby. Alternatively, the TA phonon damping can be successfully
+fitted in the framework of an empirical Havriliak - Negami (HN) relaxation
+model that includes a strong resonance-like transient contribution.",1608.01591v1
+2016-08-26,Cheillini integrability and quadratically damped oscillators,"In this paper a new approach to study an equation of the Lienard type with a
+strong quadratic damping is proposed based on Jacobi's last multiplier and
+Cheillini's integrability condition. We obtain a closed form solution of the
+transcendental characteristic equation of the Lienard type equation using the
+Lambert W-function.",1608.07377v1
+2016-11-27,Nonlinear Wave Equation with Damping: Periodic Forcing and Non-Resonant Solutions to the Kuznetsov Equation,"Existence of non-resonant solutions of time-periodic type are established for
+the Kuznetsov equation with a periodic forcing term. The equation is considered
+in a three-dimensional whole-space, half-space and bounded domain, and with
+both non-homogeneous Dirichlet and Neumann boundary values. A method based on
+Lp estimates of the corresponding linearization, namely the wave equation with
+Kelvin-Voigt damping, is employed.",1611.08883v1
+2017-02-02,Stationary solutions for stochastic damped Navier-Stokes equations in $\mathbb R^d$,"We consider the stochastic damped Navier-Stokes equations in $\mathbb R^d$
+($d=2,3$), assuming as in our previous work [4] that the covariance of the
+noise is not too regular, so It\^o calculus cannot be applied in the space of
+finite energy vector fields. We prove the existence of an invariant measure
+when $d=2$ and of a stationary solution when $d=3$.",1702.00697v1
+2017-03-08,Moderate deviations for the Langevin equation with strong damping,"In this paper, we establish a moderate deviations principle for the Langevin
+dynamics with strong damping. The weak convergence approach plays an important
+role in the proof.",1703.03033v3
+2017-03-17,Damping in a Superconducting Mechanical Resonator,"We study a mechanical resonator made of aluminum near the normal to super
+conductivity phase transition. A sharp drop in the rate of mechanical damping
+is observed below the critical temperature. The experimental results are
+compared with predictions based on the Bardeen Cooper Schrieffer theory of
+superconductivity and a fair agreement is obtained.",1703.05912v1
+2017-03-27,On the $L^{2}$-critical nonlinear Schrodinger equation with an inhomogeneous damping term,"We consider the $L^2$-critical nonlinear Schrodinger equation with an
+inhomogeneous damping term. We prove that there exists an initial data such
+that the corresponding solution is global in $H^1(R^d)$ and we give the minimal
+time of the blow up for some initial data.",1703.09101v1
+2017-06-22,Asymptotic profile of solutions for some wave equations with very strong structural damping,"We consider the Cauchy problem in R^n for some types of damped wave
+equations. We derive asymptotic profiles of solutions with weighted
+L^{1,1}(R^n) initial data by employing a simple method introduced by the first
+author. The obtained results will include regularity loss type estimates, which
+are essentially new in this kind of equations.",1706.07174v1
+2017-08-11,Global existence of a diffusion limit with damping for the compressible radiative Euler system coupled to an electromagnetic field,"We study the Cauchy problem for a system of equations corresponding to a
+singular limit of radiative hydrodynamics, namely the 3D radiative compressible
+Euler system coupled to an electromagnetic field through the MHD approximation.
+Assuming the presence of damping together with suitable smallness hypotheses
+for the data, we prove that this problem admits a unique global smooth
+solution.",1708.03681v1
+2017-08-21,A remark on the critical exponent for the semilinear damped wave equation on the half-space,"In this short notice, we prove the non-existence of global solutions to the
+semilinear damped wave equation on the half-space, and we determine the
+critical exponent for any space dimension.",1708.06429v1
+2017-12-04,Radiative seesaw models linking to dark matter candidates inspired by the DAMPE excess,"We propose two possibilities to explain an excess of electron/positron flux
+around 1.4 TeV recently reported by Dark Matter Explore (DAMPE) in the
+framework of radiative seesaw models where one of them provides a fermionic
+dark matter candidate, and the other one provides a bosonic dark matter
+candidate. We also show unique features of both models regarding neutrino mass
+structure.",1712.00941v1
+2018-01-06,Multiscale analysis of semilinear damped stochastic wave equations,"In this paper we proceed with the multiscale analysis of semilinear damped
+stochastic wave motions. The analysis is made by combining the well-known sigma
+convergence method with its stochastic counterpart, associated to some
+compactness results such as the Prokhorov and Skorokhod theorems. We derive the
+equivalent model, which is of the same type as the micro-model.",1801.02036v1
+2018-07-06,Global existence for the 3-D semilinear damped wave equations in the scattering case,"We study the global existence of solutions to semilinear damped wave
+equations in the scattering case with derivative power-type nonlinearity on
+(1+3) dimensional nontrapping asymptotically Euclidean manifolds. The main idea
+is to exploit local energy estimate, together with local existence to convert
+the parameter $\mu$ to small one.",1807.02403v1
+2018-09-22,Asymptotic behavior of solutions to 3D incompressible Navier-Stokes equations with damping,"In this paper, we study the upper bound of the time decay rate of solutions
+to the Navier-Stokes equations and generalized Navier-Stokes equations with
+damping term $|u|^{\beta-1}u$ ($\beta>1$) in $\mathbb{R}^3$.",1809.08394v2
+2018-10-22,Optimal leading term of solutions to wave equations with strong damping terms,"We analyze the asymptotic behavior of solutions to wave equations with strong
+damping terms. If the initial data belong to suitable weighted $L^1$ spaces,
+lower bounds for the difference between the solutions and the leading terms in
+the Fourier space are obtained, which implies the optimality of expanding
+methods and some estimates proposed in this paper.",1810.09114v1
+2018-10-29,Apples with Apples comparison of 3+1 conformal numerical relativity schemes,"This paper contains a comprehensive comparison catalog of `Apples with
+Apples' tests for the BSSNOK, CCZ4 and Z4c numerical relativity schemes, with
+and without constraint damping terms for the latter two. We use basic numerical
+methods and reach the same level of accuracy as existing results in the
+literature. We find that the best behaving scheme is generically CCZ4 with
+constraint damping terms.",1810.12346v1
+2018-11-07,Statistical complexity of the quasiperiodical damped systems,"We consider the concept of statistical complexity to write the
+quasiperiodical damped systems applying the snapshot attractors. This allows us
+to understand the behaviour of these dynamical systems by the probability
+distribution of the time series making a difference between the regular, random
+and structural complexity on finite measurements. We interpreted the
+statistical complexity on snapshot attractor and determined it on the
+quasiperiodical forced pendulum.",1811.02958v1
+2018-12-13,Rapid exponential stabilization of a 1-D transmission wave equation with in-domain anti-damping,"We consider the problem of pointwise stabilization of a one-dimensional wave
+equation with an internal spatially varying anti-damping term. We design a
+feedback law based on the backstepping method and prove exponential stability
+of the closed-loop system with a desired decay rate.",1812.11035v1
+2019-01-20,Stationary Solutions of Damped Stochastic 2-dimensional Euler's Equation,"Existence of stationary point vortices solution to the damped and
+stochastically driven Euler's equation on the two dimensional torus is proved,
+by taking limits of solutions with finitely many vortices. A central limit
+scaling is used to show in a similar manner the existence of stationary
+solutions with white noise marginals.",1901.06744v1
+2019-03-13,Solar $p$-mode damping rates: insight from a 3D hydrodynamical simulation,"Space-borne missions CoRoT and Kepler have provided a rich harvest of
+high-quality photometric data for solar-like pulsators. It is now possible to
+measure damping rates for hundreds of main-sequence and thousands of red-giant.
+However, among the seismic parameters, mode damping rates remain poorly
+understood and thus barely used for inferring the physical properties of stars.
+Previous approaches to model mode damping rates were based on mixing-length
+theory or a Reynolds-stress approach to model turbulent convection. While able
+to grasp the main physics of the problem, those approaches are of little help
+to provide quantitative estimates as well as a definitive answer on the
+relative contribution of each physical mechanism. Our aim is thus to assess the
+ability of 3D hydrodynamical simulations to infer the physical mechanisms
+responsible for damping of solar-like oscillations. To this end, a solar
+high-spatial resolution and long-duration hydrodynamical 3D simulation computed
+with the ANTARES code allows probing the coupling between turbulent convection
+and the normal modes of the simulated box. Indeed, normal modes of the
+simulation experience realistic driving and damping in the super-adiabatic
+layers of the simulation. Therefore, investigating the properties of the normal
+modes in the simulation provides a unique insight into the mode physics. We
+demonstrate that such an approach provides constraints on the solar damping
+rates and is able to disentangle the relative contribution related to the
+perturbation of the turbulent pressure, the gas pressure, the radiative flux,
+and the convective flux contributions. Finally, we conclude that using the
+normal modes of a 3D numerical simulation is possible and is potentially able
+to unveil the respective role of the different physical mechanisms responsible
+for mode damping provided the time-duration of the simulation is long enough.",1903.05479v1
+2019-04-15,Carleman estimate for an adjoint of a damped beam equation and an application to null controllability,"In this article we consider a control problem of a linear Euler-Bernoulli
+damped beam equation with potential in dimension one with periodic boundary
+conditions. We derive a new Carleman estimate for an adjoint of the equation
+under consideration. Then using a well known duality argument we obtain
+explicitly the control function which can be used to drive the solution
+trajectory of the control problem to zero state.",1904.07038v1
+2019-05-01,Dissipative structure and diffusion phenomena for doubly dissipative elastic waves in two space dimensions,"In this paper we study the Cauchy problem for doubly dissipative elastic
+waves in two space dimensions, where the damping terms consist of two different
+friction or structural damping. We derive energy estimates and diffusion
+phenomena with different assumptions on initial data. Particularly, we find the
+dominant influence on diffusion phenomena by introducing a new threshold of
+diffusion structure.",1905.00257v1
+2019-07-12,Non-Existence of Periodic Orbits for Forced-Damped Potential Systems in Bounded Domains,"We prove Lr-estimates on periodic solutions of periodically-forced,
+linearly-damped mechanical systems with polynomially-bounded potentials. The
+estimates are applied to obtain a non-existence result of periodic solutions in
+bounded domains, depending on an upper bound on the gradient of the potential.
+The results are illustrated on examples.",1907.05778v1
+2019-09-02,On the inclusion of damping terms in the hyperbolic MBO algorithm,"The hyperbolic MBO is a threshold dynamic algorithm which approximates
+interfacial motion by hyperbolic mean curvature flow. We introduce a
+generalization of this algorithm for imparting damping terms onto the equation
+of motion. We also construct corresponding numerical methods, and perform
+numerical tests. We also use our results to show that the generalized
+hyperbolic MBO is able to approximate motion by the standard mean curvature
+flow.",1909.00552v1
+2019-09-07,Lindblad dynamics of the damped and forced quantum harmonic oscillator: General solution,"The quantum dynamics of a damped and forced harmonic oscillator described by
+a Lindblad master equation is analyzed. The master equation is converted into a
+matrix-vector representation and the resulting non-Hermitian Schr\""odinger
+equation is solved by Lie-algebraic techniques allowing the construction of the
+general solution for the density operator.",1909.03206v1
+2019-11-01,Convergence of a damped Newton's method for discrete Monge-Ampere functions with a prescribed asymptotic cone,"We prove the convergence of a damped Newton's method for the nonlinear system
+resulting from a discretization of the second boundary value problem for the
+Monge-Ampere equation. The boundary condition is enforced through the use of
+the notion of asymptotic cone. The differential operator is discretized based
+on a partial discrete analogue of the subdifferential.",1911.00260v2
+2019-12-17,"Comment on ""On the Origin of Frictional Energy Dissipation""","In their interesting study (Ref. [1]) Hu et al have shown that for a simple
+""harmonium"" solid model the slip-induced motion of surface atoms is close to
+critically damped. This result is in fact well known from studies of
+vibrational damping of atoms and molecules at surfaces. However, for real
+practical cases the situation may be much more complex and the conclusions of
+Hu et al invalid.",1912.07799v1
+2020-01-23,Nonlinear inviscid damping for a class of monotone shear flows in finite channel,"We prove the nonlinear inviscid damping for a class of monotone shear flows
+in $T\times [0,1]$ for initial perturbation in Gevrey-$1/s$($s>2$) class with
+compact support. The main idea of the proof is to use the wave operator of a
+slightly modified Rayleigh operator in a well chosen coordinate system.",2001.08564v1
+2020-02-26,Bistability in the dissipative quantum systems I: Damped and driven nonlinear oscillator,"We revisit quantum dynamics of the damped and driven nonlinear oscillator. In
+the classical case this system has two stationary solutions (the limit cycles)
+in the certain parameter region, which is the origin of the celebrated
+bistability phenomenon. The quantum-classical correspondence for the oscillator
+dynamics is discussed in details.",2002.11373v1
+2020-04-08,Scattering and asymptotic order for the wave equations with the scale-invariant damping and mass,"We consider the linear wave equation with the time-dependent scale-invariant
+damping and mass. We also treat the corresponding equation with the energy
+critical nonlinearity. Our aim is to show that the solution scatters to a
+modified linear wave solution and to obtain its asymptotic order.",2004.03832v2
+2020-04-24,Infinite energy solutions for weakly damped quintic wave equations in $\mathbb{R}^3$,"The paper gives a comprehensive study of infinite-energy solutions and their
+long-time behavior for semi-linear weakly damped wave equations in
+$\mathbb{R}^3$ with quintic nonlinearities. This study includes global
+well-posedness of the so-called Shatah-Struwe solutions, their dissipativity,
+the existence of a locally compact global attractors (in the uniformly local
+phase spaces) and their extra regularity.",2004.11864v1
+2020-07-30,Delta shock solution to the generalized one-dimensional zero-pressure gas dynamics system with linear damping,"In this paper, we propose a time-dependent viscous system and by using the
+vanishing viscosity method we show the existence of delta shock solution for a
+particular $2 \times 2$ system of conservation laws with linear damping.",2007.15184v2
+2020-08-06,On global attractors for 2D damped driven nonlinear Schrödinger equations,"Well-posedness and global attractor are established for 2D damped driven
+nonlinear Schr\""odinger equation with almost periodic pumping in a bounded
+region. The key role is played by a novel application of the energy equation.",2008.02741v1
+2020-08-30,Influence of dissipation on extreme oscillations of a forced anharmonic oscillator,"Dynamics of a periodically forced anharmonic oscillator (AO) with cubic
+nonlinearity, linear damping, and nonlinear damping, is studied. To begin with,
+the authors examine the dynamics of an AO. Due to this symmetric nature, the
+system has two neutrally stable elliptic equilibrium points in positive and
+negative potential-wells. Hence, the unforced system can exhibit both
+single-well and double-well periodic oscillations depending on the initial
+conditions. Next, the authors include nonlinear damping into the system. Then,
+the symmetry of the system is broken instantly and the stability of the two
+elliptic points is altered to result in stable focus and unstable focus in the
+positive and negative potential-wells, respectively. Consequently, the system
+is dual-natured and is either non-dissipative or dissipative, depending on
+location in the phase space. Furthermore, when one includes a periodic external
+forcing with suitable parameter values into the nonlinearly damped AO system
+and starts to increase the damping strength, the symmetry of the system is not
+broken right away, but it occurs after the damping reaches a threshold value.
+As a result, the system undergoes a transition from double-well chaotic
+oscillations to single-well chaos mediated through extreme events (EEs).
+Furthermore, it is found that the large-amplitude oscillations developed in the
+system are completely eliminated if one incorporates linear damping into the
+system. The numerically calculated results are in good agreement with the
+theoretically obtained results on the basis of Melnikov's function. Further, it
+is demonstrated that when one includes linear damping into the system, this
+system has a dissipative nature throughout the entire phase space of the
+system. This is believed to be the key to the elimination of EEs.",2008.13172v1
+2020-09-18,Vanishing viscosity limit for Riemann solutions to a $2 \times 2$ hyperbolic system with linear damping,"In this paper, we propose a time-dependent viscous system and by using the
+vanishing viscosity method we show the existence of %delta shock solution
+solutions for the Riemann problem to a particular $2 \times 2$ system of
+conservation laws with linear damping.",2009.09041v1
+2020-11-28,A Smoluchowski-Kramers approximation for an infinite dimensional system with state-dependent damping,"We study the validity of a Smoluchowski-Kramers approximation for a class of
+wave equations in a bounded domain of $\mathbb{R}^n$ subject to a
+state-dependent damping and perturbed by a multiplicative noise. We prove that
+in the small mass limit the solution converges to the solution of a stochastic
+quasilinear parabolic equation where a noise-induced extra drift is created.",2011.14236v2
+2020-12-13,Uniform Stabilization of the Petrovsky-Wave Nonlinear coupled system with strong damping,"This paper concerns the well-posedness and uniform stabilization of the
+Petrovsky-Wave Nonlinear coupled system with strong damping. Existence of
+global weak solutions for this problem is established by using the Galerkin
+method. Meanwhile, under a clever use of the multiplier method, we estimate the
+total energy decay rate.",2012.07109v3
+2021-03-24,"On the long-time statistical behavior of smooth solutions of the weakly damped, stochastically-driven KdV equation","This paper considers the damped periodic Korteweg-de Vries (KdV) equation in
+the presence of a white-in-time and spatially smooth stochastic source term and
+studies the long-time behavior of solutions. We show that the integrals of
+motion for KdV can be exploited to prove regularity and ergodic properties of
+invariant measures for damped stochastic KdV. First, by considering non-trivial
+modifications of the integrals of motion, we establish Lyapunov structure by
+proving that moments of Sobolev norms of solutions at all orders of regularity
+are bounded globally-in-time; existence of invariant measures follows as an
+immediate consequence. Next, we prove a weak Foias-Prodi type estimate for
+damped stochastic KdV, for which the synchronization occurs in expected value.
+This estimate plays a crucial role throughout our subsequent analysis. As a
+first novel application, we combine the Foias-Prodi estimate with the Lyapunov
+structure to establish that invariant measures are supported on $C^\infty$
+functions provided that the external driving forces belong to $C^\infty$. We
+then establish ergodic properties of invariant measures, treating the regimes
+of arbitrary damping and large damping separately. For arbitrary damping, we
+demonstrate that the framework of `asymptotic coupling' can be implemented for
+a compact proof of uniqueness of the invariant measure provided that
+sufficiently many directions in phase space are stochastically forced. Our
+proof is paradigmatic for SPDEs for which a weak Foias-Prodi type property
+holds. Lastly, for large damping, we establish the existence of a spectral gap
+with respect to a Wasserstein-like distance, and exponential mixing and
+uniqueness of the invariant measure follows.",2103.12942v2
+2021-04-21,On absorbing set for 3D Maxwell--Schrödinger damped driven equations in bounded region,"We consider the 3D damped driven Maxwell--Schr\""odinger equations in a
+bounded region under suitable boundary conditions. We establish new a priori
+estimates, which provide the existence of global finite energy weak solutions
+and bounded absorbing set. The proofs rely on the Sobolev type estimates for
+magnetic Schr\""odinger operator.",2104.10723v1
+2021-06-23,Pitt inequality for the linear structurally damped $σ$-evolution equations,"This work is devoted to improve the time decay estimates for the solution and
+some of its derivatives of the linear structurally damped $\sigma$-evolution
+equations. The Pitt inequality is the main tool provided that the initial data
+lies in some weighted spaces.",2106.12342v1
+2021-07-22,Dimension estimates for the attractor of the regularized damped Euler equations on the sphere,"We prove existence of the global attractor of the damped and driven
+Euler--Bardina equations on the 2D sphere and on arbitrary domains on the
+sphere
+  and give explicit estimates of its fractal dimension in terms of the physical
+parameters.",2107.10779v1
+2021-09-22,State-space representation of Matérn and Damped Simple Harmonic Oscillator Gaussian processes,"Gaussian processes (GPs) are used widely in the analysis of astronomical time
+series. GPs with rational spectral densities have state-space representations
+which allow O(n) evaluation of the likelihood. We calculate analytic state
+space representations for the damped simple harmonic oscillator and the
+Mat\'ern 1/2, 3/2 and 5/2 processes.",2109.10685v1
+2021-10-21,Stability properties of dissipative evolution equations with nonautonomous and nonlinear damping,"In this paper, we obtain some stability results of (abstract) dissipative
+evolution equations with a nonautonomous and nonlinear damping using the
+exponential stability of the retrograde problem with a linear and autonomous
+feedback and a comparison principle. We then illustrate our abstract statements
+for different concrete examples, where new results are achieved. In a
+preliminary step, we prove some well-posedness results for some nonlinear and
+nonautonomous evolution equations.",2110.11122v1
+2021-11-23,Logistic damping effect in chemotaxis models with density-suppressed motility,"This paper is concerned with a parabolic-elliptic chemotaxis model with
+density-suppressed motility and general logistic source in an $n$-dimensional
+smooth bounded domain with Neumann boundary conditions. Under the minimal
+conditions for the density-suppressed motility function, we explore how strong
+the logistic damping can warrant the global boundedness of solutions, and
+further establish the asymptotic behavior of solutions on top of the
+conditions.",2111.11669v1
+2022-01-04,Global existence and decay estimates for a viscoelastic plate equation with nonlinear damping and logarithmic nonlinearity,"In this article, we consider a viscoelastic plate equation with a logarithmic
+nonlinearity in the presence of nonlinear frictional damping term. Using the
+the Faedo-Galerkin method we establish the global existence of the solution of
+the problem and we also prove few general decay rate results.",2201.00983v1
+2022-01-20,Long Time Decay of Leray Solution of 3D-NSE With Damping,"In \cite{CJ}, the authors show that the Cauchy problem of the Navier-Stokes
+equations with damping $\alpha|u|^{\beta-1}u(\alpha>0,\;\beta\geq1)$ has global
+weak solutions in $L^2(\R^3)$. In this paper, we prove the uniqueness, the
+continuity in $L^2$ for $\beta>3$, also the large time decay is proved for
+$\beta\geq\frac{10}3$. Fourier analysis and standard techniques are used.",2201.08427v1
+2022-02-20,On a non local non-homogeneous fractional Timoshenko system with frictional and viscoelastic damping terms,"We are devoted to the study of a nonhomogeneous time-fractional Timoshenko
+system with frictional and viscoelastic damping terms. We are concerned with
+the well-posedness of the given problem. The approach relies on some
+functional-analysis tools, operator theory, a prori estimates, and density
+arguments.",2202.09879v1
+2022-04-05,Large time behavior of solutions to nonlinear beam equations,"In this note we analyze the large time behavior of solutions to a class of
+initial/boundary problems involving a damped nonlinear beam equation. We show
+that under mild conditions on the damping term of the equation of motions the
+solutions of the dynamical problem converge to the solution of the stationary
+problem. We also show that this convergence is exponential.",2204.02151v1
+2022-05-09,Energy asymptotics for the strongly damped Klein-Gordon equation,"We consider the strongly damped Klein Gordon equation for defocusing
+nonlinearity and we study the asymptotic behaviour of the energy for periodic
+solutions. We prove first the exponential decay to zero for zero mean
+solutions. Then, we characterize the limit of the energy, when the time tends
+to infinity, for solutions with small enough initial data and we finally prove
+that such limit is not necessary zero.",2205.04205v1
+2022-06-07,Asymptotic study of Leray Solution of 3D-NSE With Exponential Damping,"We study the uniqueness, the continuity in $L^2$ and the large time decay for
+the Leray solutions of the $3D$ incompressible Navier-Stokes equations with the
+nonlinear exponential damping term $a (e^{b |u|^{\bf 2}}-1)u$, ($a,b>0$)
+studied by the second author in \cite{J1}.",2206.03138v1
+2022-06-25,"Decay estimate in a viscoelastic plate equation with past history, nonlinear damping, and logarithmic nonlinearity","In this article, we consider a viscoelastic plate equation with past history,
+nonlinear damping, and logarithmic nonlinearity. We prove explicit and general
+decay rate results of the solution to the viscoelastic plate equation with past
+history. Convex properties, logarithmic inequalities, and generalised Young's
+inequality are mainly used to prove the decay estimate.",2206.12561v1
+2022-09-07,Blow up and lifespan estimates for systems of semi-linear wave equations with dampings and potentials,"In this paper, we consider the semi-linear wave systems with
+power-nonlinearities and space-dependent dampings and potentials. We obtain the
+blow-up regions for three types wave systems as well as the lifespan estimates.",2209.02920v1
+2022-12-14,Gevrey regularity for the Euler-Bernoulli beam equation with localized structural damping,"We study a Euler-Bernoulli beam equation with localized discontinuous
+structural damping. As our main result, we prove that the associated
+$C_0$-semigroup $(S(t))_{t\geq0}$ is of Gevrey class $\delta>24$ for $t>0$,
+hence immediately differentiable. Moreover, we show that $(S(t))_{t\geq0}$ is
+exponentially stable.",2212.07110v1
+2022-12-28,On extended lifespan for 1d damped wave equation,"In this manuscript, a sharp lifespan estimate of solutions to semilinear
+classical damped wave equation is investigated in one dimensional case, when
+the sum of initial position and speed is $0$ pointwisely. Especially, an
+extension of lifespan is shown in this case. Moreover, existence of some global
+solutions are obtained by a direct computation.",2212.13845v1
+2023-02-06,Uniform stabilization of an acoustic system,"We study the problem of stabilization for the acoustic system with a
+spatially distributed damping. With imposing hypothesis on the structural
+properties of the damping term, we identify exponential decay of solutions with
+growing time.",2302.02726v1
+2023-05-22,Fast energy decay for wave equation with a monotone potential and an effective damping,"We consider the total energy decay of the Cauchy problem for wave equations
+with a potential and an effective damping. We treat it in the whole
+one-dimensional Euclidean space. Fast energy decay is established with the help
+of potential. The proofs of main results rely on a multiplier method and
+modified techniques adopted in [8].",2305.12666v1
+2023-08-03,Blow-up for semilinear wave equations with damping and potential in high dimensional Schwarzschild spacetime,"In this work, we study the blow up results to power-type semilinear wave
+equation in the high dimensional Schwarzschild spacetime, with damping and
+potential terms. We can obtain the upper bound estimates of lifespan without
+the assumption that the support of the initial date should be far away from the
+black hole.",2308.01691v1
+2023-08-22,Lifespan estimates for 1d damped wave equation with zero moment initial data,"In this manuscript, a sharp lifespan estimate of solutions to semilinear
+classical damped wave equation is investigated in one dimensional case when the
+Fourier 0th moment of sum of initial position and speed is $0$. Especially, it
+is shown that the behavior of lifespan changes with $p=3/2$ with respect to the
+size of the initial data.",2308.11113v1
+2023-09-01,Damped Euler system with attractive Riesz interaction forces,"We consider the barotropic Euler equations with pairwise attractive Riesz
+interactions and linear velocity damping in the periodic domain. We establish
+the global-in-time well-posedness theory for the system near an equilibrium
+state. We also analyze the large-time behavior of solutions showing the
+exponential rate of convergence toward the equilibrium state as time goes to
+infinity.",2309.00210v1
+2023-10-02,The damped wave equation and associated polymer,"Considering the damped wave equation with a Gaussian noise $F$ where $F$ is
+white in time and has a covariance function depending on spatial variables, we
+will see that this equation has a mild solution which is stationary in time
+$t$. We define a weakly self-avoiding polymer with intrinsic length $J$
+associated to this SPDE. Our main result is that the polymer has an effective
+radius of approximately $J^{5/3}$.",2310.01631v1
+2023-10-17,Indirect boundary stabilization for weakly coupled degenerate wave equations under fractional damping,"In this paper, we consider the well-posedness and stability of a
+one-dimensional system of degenerate wave equations coupled via zero order
+terms with one boundary fractional damping acting on one end only. We prove
+optimal polynomial energy decay rate of order $1/t^{(3-\tau)}$. The method is
+based on the frequency domain approach combined with multiplier technique.",2310.11174v1
+2024-03-11,Uniform estimates for solutions of nonlinear focusing damped wave equations,"For a damped wave (or Klein-Gordon) equation on a bounded domain, with a
+focusing power-like nonlinearity satisfying some growth conditions, we prove
+that a global solution is bounded in the energy space, uniformly in time. Our
+result applies in particular to the case of a cubic equation on a bounded
+domain of dimension 3.",2403.06541v1
+1995-10-27,A modified R1 X R1 method for helioseismic rotation inversions,"We present an efficient method for two dimensional inversions for the solar
+rotation rate using the Subtractive Optimally Localized Averages (SOLA) method
+and a modification of the R1 X R1 technique proposed by Sekii (1993). The SOLA
+method is based on explicit construction of averaging kernels similar to the
+Backus-Gilbert method. The versatility and reliability of the SOLA method in
+reproducing a target form for the averaging kernel, in combination with the
+idea of the R1 X R1 decomposition, results in a computationally very efficient
+inversion algorithm. This is particularly important for full 2-D inversions of
+helioseismic data in which the number of modes runs into at least tens of
+thousands.",9510143v1
+1997-10-22,Globular Cluster Microlensing: Globular Clusters as Microlensing Targets,"We investigate the possibility of using globular clusters as targets for
+microlensing searches. Such searches will be challenging and require more
+powerful telescopes than now employed, but are feasible in the 0 future.
+Although expected event rates are low, we show that the wide variety of lines
+of sight to globular clusters greatly enhances the ability to distinguish
+between halo models using microlensing observations as compared to LMC/SMC
+observations alone.",9710251v1
+2002-12-17,An Intrinsic Baldwin Effect in the H-beta Broad Emission Line in the Spectrum of NGC 5548,"We investigate the possibility of an intrinsic Baldwin Effect (i.e.,nonlinear
+emission-line response to continuum variations) in the broad H-beta emission
+line of the active galaxy NGC 5548 using cross-correlation techniques to remove
+light travel-time effects from the data. We find a nonlinear relationship
+between the H-beta emission line and continuum fluxes that is in good agreement
+with theoretical predictions. We suggest that similar analysis of multiple
+lines might provide a useful diagnostic of physical conditions in the
+broad-line region.",0212379v1
+2002-12-28,Detecting supersymmetric dark matter in M31 with CELESTE ?,"It is widely believed that dark matter exists within galaxies and clusters of
+galaxies. Under the assumption that this dark matter is composed of the
+lightest, stable supersymmetric particle, assumed to be the neutralino, the
+feasibility of its indirect detection via observations of a diffuse gamma-ray
+signal due to neutralino annihilation within M31 is examined.",0212560v1
+2003-03-18,Model-Independent Reionization Observables in the CMB,"We represent the reionization history of the universe as a free function in
+redshift and study the potential for its extraction from CMB polarization
+spectra. From a principal component analysis, we show that the ionization
+history information is contained in 5 modes, resembling low-order Fourier modes
+in redshift space. The amplitude of these modes represent a compact description
+of the observable properties of reionization in the CMB, easily predicted given
+a model for the ionization fraction. Measurement of these modes can ultimately
+constrain the total optical depth, or equivalently the initial amplitude of
+fluctuations to the 1% level regardless of the true model for reionization.",0303400v1
+2006-05-08,Discovery of an Extended Halo of Metal-poor Stars in the Andromeda Spiral Galaxy,This paper has been withdrawn. Please see astro-ph/0502366.,0605172v3
+1995-01-02,Dynamics of homogeneous magnetizations in strong transverse driving fields,"Spatially homogeneous solutions of the Landau--Lifshitz--Gilbert equation are
+analysed. The conservative as well as the dissipative case is considered
+explicitly. For the linearly polarized driven Hamiltonian system we apply
+canonical perturbation theory to uncover the main resonances as well as the
+global phase space structure. In the case of circularly polarized driven
+dissipative motion we present the complete bifurcation diagram including
+bifurcations up to codimension three.",9501002v1
+2000-09-18,Electronic properties of the degenerate Hubbard Model : A dynamical mean field approach,"We have investigated electronic properties of the degenerate multi-orbital
+Hubbard model, in the limit of large spatial dimension. A new local model,
+including a doubly degenerate strongly correlated site has been introduced and
+solved in the framework of the non-crossing approximation (NCA). Mott-Hubbard
+transitions have been examined in details, including the calculation of Coulomb
+repulsion critical values and electronic densities of states for any regime of
+parameters.",0009253v1
+2001-01-11,Theoretical and Experimental Approach to Spin Dynamics in Thin Magnetic Films,"The Landau-Lifshitz (L-L) equation describing the time dependence of the
+magnetisation vector is numerically integrated fully without any simplifying
+assumptions in the time domain and the magnetisation time series obtained is
+Fourier transformed (FFT) to yield the permeability spectrum up to 10 GHz. The
+non linear results are compared to the experimental results obtained on
+magnetic amorphous thin films of Co-Zr, Co-Zr-Re. We analyse our results with
+the frequency response obtained directly from the Landau-Lifshitz equation as
+well as with the second order Gilbert frequency response.",0101154v1
+2004-08-13,Finite lattice size effect in the ground state phase diagram of quasi-two-dimensional magnetic dipolar dots array with perpendicular anisotropy,"A prototype Hamiltonian for the generic patterned magnetic structures, of
+dipolar interaction with perpendicular anisotropy, is investigated within the
+finite-size framework by Landau-Lifshift-Gilbert classical spin dynamics.
+Modifications on the ground state phase diagram are discussed with an emphasis
+on the disappearance of continuous degeneracy in the ground state of in-plane
+phase due to the finite lattice size effect. The symmetry-governed ground state
+evolution upon the lattice size increase provides a critical insight into the
+systematic transition to the infinite extreme.",0408324v1
+2004-10-01,Current-spin coupling for ferromagnetic domain walls in fine wires,"The coupling between a current and a domain wall is examined. In the presence
+of a finite current and the absence of a potential which breaks the
+translational symmetry, there is a perfect transfer of angular momentum from
+the conduction electrons to the wall. As a result, the ground state is in
+uniform motion. This remains the case when relaxation is accounted for. This is
+described by, appropriately modified, Landau-Lifshitz-Gilbert equations.",0410035v1
+2004-12-17,Hysteresis loops of magnetic thin films with perpendicular anisotropy,"We model the magnetization of quasi two-dimensional systems with easy
+perpendicular (z-)axis anisotropy upon change of external magnetic field along
+z. The model is derived from the Landau-Lifshitz-Gilbert equation for
+magnetization evolution, written in closed form in terms of the z component of
+the magnetization only. The model includes--in addition to the external
+field--magnetic exchange, dipolar interactions and structural disorder. The
+phase diagram in the disorder/interaction strength plane is presented, and the
+different qualitative regimes are analyzed. The results compare very well with
+observed experimental hysteresis loops and spatial magnetization patterns, as
+for instance for the case of Co-Pt multilayers.",0412461v1
+2006-01-11,Relaxing-Precessional Magnetization Switching,"A new way of magnetization switching employing both the spin-transfer torque
+and the torque by a magnetic field is proposed. The solution of the
+Landau-Lifshitz-Gilbert equation shows that the dynamics of the magnetization
+in the initial stage of the switching is similar to that in the precessional
+switching, while that in the final stage is rather similar to the relaxing
+switching. We call the present method the relaxing-precessional switching. It
+offers a faster and lower-power-consuming way of switching than the relaxing
+switching and a more controllable way than the precessional switching.",0601227v1
+2006-04-01,Magnetization reversal through synchronization with a microwave,"Based on the Landau-Lifshitz-Gilbert equation, it can be shown that a
+circularly-polarized microwave can reverse the magnetization of a Stoner
+particle through synchronization. In comparison with magnetization reversal
+induced by a static magnetic field, it can be shown that when a proper
+microwave frequency is used the minimal switching field is much smaller than
+that of precessional magnetization reversal. A microwave needs only to overcome
+the energy dissipation of a Stoner particle in order to reverse magnetization
+unlike the conventional method with a static magnetic field where the switching
+field must be of the order of magnetic anisotropy.",0604013v1
+2006-06-26,Self Consistent NEGF-LLG Model for Spin-Torque Based Devices,"We present here a self consistent solution of quantum transport, using the
+Non Equilibrium Green's Function (NEGF) method, and magnetization dynamics,
+using the Landau-Lifshitz-Gilbert (LLG) formulation. We have applied this model
+to study current induced magnetic switching due to `spin torque' in a device
+where the electronic transport is ballistic and the free magnetic layer is
+sandwiched between two anti-parallel ferromagnetic contacts. The device shows
+clear hysteretic current-voltage characteristics, at room temperature, with a
+sharp transition between the bistable states and hence can be used as a
+non-volatile memory. We show that the proposed design may allow reducing the
+switching current by an order of magnitude.",0606648v2
+2006-07-25,Thermally-Assisted Current-Driven Domain Wall Motion,"Starting from the stochastic Landau-Lifschitz-Gilbert equation, we derive
+Langevin equations that describe the nonzero-temperature dynamics of a rigid
+domain wall. We derive an expression for the average drift velocity of the
+domain wall as a function of the applied current, and find qualitative
+agreement with recent magnetic semiconductor experiments. Our model implies
+that at any nonzero temperature the average domain-wall velocity initially
+varies linearly with current, even in the absence of non-adiabatic spin
+torques.",0607663v1
+2006-09-08,Large cone angle magnetization precession of an individual nanomagnet with dc electrical detection,"We demonstrate on-chip resonant driving of large cone-angle magnetization
+precession of an individual nanoscale permalloy element. Strong driving is
+realized by locating the element in close proximity to the shorted end of a
+coplanar strip waveguide, which generates a microwave magnetic field. We used a
+microwave frequency modulation method to accurately measure resonant changes of
+the dc anisotropic magnetoresistance. Precession cone angles up to $9^{0}$ are
+determined with better than one degree of resolution. The resonance peak shape
+is well-described by the Landau-Lifshitz-Gilbert equation.",0609190v1
+2006-12-30,Low relaxation rate in a low-Z alloy of iron,"The longest relaxation time and sharpest frequency content in ferromagnetic
+precession is determined by the intrinsic (Gilbert) relaxation rate \emph{$G$}.
+For many years, pure iron (Fe) has had the lowest known value of $G=\textrm{57
+Mhz}$ for all pure ferromagnetic metals or binary alloys. We show that an
+epitaxial iron alloy with vanadium (V) possesses values of $G$ which are
+significantly reduced, to 35$\pm$5 Mhz at 27% V. The result can be understood
+as the role of spin-orbit coupling in generating relaxation, reduced through
+the atomic number $Z$.",0701004v1
+2004-09-07,Distance properties of expander codes,"We study the minimum distance of codes defined on bipartite graphs. Weight
+spectrum and the minimum distance of a random ensemble of such codes are
+computed. It is shown that if the vertex codes have minimum distance $\ge 3$,
+the overall code is asymptotically good, and sometimes meets the
+Gilbert-Varshamov bound.
+  Constructive families of expander codes are presented whose minimum distance
+asymptotically exceeds the product bound for all code rates between 0 and 1.",0409010v1
+1996-06-11,Radiative corrections to $e^+e^-\to H^+ H^-$,"We study the 1-loop corrections to the charged Higgs production both in the
+Minimal Supersymmetric Standard Model (MSSM) and in a more general type II
+two-Higgs-doublet model (THDM-II). We consider the full set of corrections
+(including soft photon contributions as well as box diagrams), and define a
+parametrization that allows a comparison between the two models. Besides the
+soft photon radiation there can be prominent model-dependent effects.",9606300v1
+1997-05-15,Analytic constraints from electroweak symmetry breaking in the MSSM,"We report on how a straightforward (albeit technically involved) analytic
+study of the 1-loop effective potential in the Minimal Supersymmetric Standard
+Model, modifies the usual electroweak symmetry breaking conditions involving
+$\tan \beta$ and the other free parameters of the model. The study implies new
+constraints which (in contrast with the existing ones like $1 \leq \tan \beta
+\leq m_t/m_b$) are fully model-independent and exclude more restrictively a
+region around $\tan \beta \sim 1$. Further results of this study will be only
+touched upon here.",9705330v1
+1998-10-01,Extracting chargino/neutralino mass parameters from physical observables,"I report on two papers, hep-ph/9806279 and hep-ph/9807336, where
+complementary strategies are proposed for the determination of the
+chargino/neutralino sector parameters, $M_1, M_2, \mu $ and $\tan \beta$, from
+the knowledge of some physical observables. This determination and the
+occurrence of possible ambiguities are studied as far as possible analytically
+within the context of the unconstrained MSSM, assuming however no CP-violation.",9810214v1
+1999-12-28,Associated H$^{-}$ W$^{+}$ Production in High Energy $e^+e^-$ Collisions,"We study the associated production of charged Higgs bosons with $W$ gauge
+bosons in high energy $e^+ e^-$ collisions at the one loop level. We present
+the analytical results and give a detailed discussion for the total cross
+section predicted in the context of a general Two Higgs Doublet Model (THDM).",9912527v2
+2001-03-25,"Comment on ``Infrared Fixed Point Structure in Minimal Supersymmetric Standard Model with Baryon and Lepton Number Violation""","We reconsider the Infrared Quasi Fixed Points which were studied recently in
+the literature in the context of the Baryon and Lepton number violating Minimal
+Supersymmetric Standard Model (hep-ph/0011274). The complete analysis requires
+further care and reveals more structure than what was previously shown. The
+formalism we develop here is quite general, and can be readily applied to a
+large class of models.",0103270v1
+1991-11-21,"""the Instability of String-Theoretic Black Holes""","It is demonstrated that static, charged, spherically--symmetric black holes
+in string theory are classically and catastrophically unstable to linearized
+perturbations in four dimensions, and moreover that unstable modes appear for
+arbitrarily small positive values of the charge. This catastrophic classical
+instability dominates and is distinct from much smaller and less significant
+effects such as possible quantum mechanical evaporation. The classical
+instability of the string--theoretic black hole contrasts sharply with the
+situation which obtains for the Reissner--Nordstr\""om black hole of general
+relativity, which has been shown by Chandrasekhar to be perfectly stable to
+linearized perturbations at the event horizon.",9111042v1
+1997-12-09,The combinatorics of biased riffle shuffles,"This paper studies biased riffle shuffles, first defined by Diaconis, Fill,
+and Pitman. These shuffles generalize the well-studied Gilbert-Shannon-Reeds
+shuffle and convolve nicely. An upper bound is given for the time for these
+shuffles to converge to the uniform distribution; this matches lower bounds of
+Lalley. A careful version of a bijection of Gessel leads to a generating
+function for cycle structure after one of these shuffles and gives new results
+about descents in random permutations. Results are also obtained about the
+inversion and descent structure of a permutation after one of these shuffles.",9712240v1
+2000-08-16,Homotopies and automorphisms of crossed modules of groupoids,"We give a detailed description of the structure of the actor 2-crossed module
+related to the automorphisms of a crossed module of groupoids. This generalises
+work of Brown and Gilbert for the case of crossed modules of groups, and part
+of this is needed for work on 2-dimensional holonomy to be developed elsewhere
+(see math.DG/0009082).",0008117v2
+2005-06-14,Transitive and Self-dual Codes Attaining the Tsfasman-Vladut-Zink Bound,"We introduce - as a generalization of cyclic codes - the notion of transitive
+codes, and we show that the class of transitive codes is asymptotically good.
+Even more, transitive codes attain the Tsfasman-Vladut-Zink bound over F_q, for
+all aquares q=l^2. We also show that self-orthogonal and self-dual codes attain
+the Tsfasman-Vladut-Zink bound, thus improving previous results about self-dual
+codes attaining the Gilbert-Varshamov bound. The main tool is a new
+asymptotically optimal tower (E_n) of function fields over F_q where all
+extensions E_n/E_0 are Galois.",0506264v1
+2005-09-01,Counting unlabelled toroidal graphs with no K33-subdivisions,"We provide a description of unlabelled enumeration techniques, with complete
+proofs, for graphs that can be canonically obtained by substituting 2-pole
+networks for the edges of core graphs. Using structure theorems for toroidal
+and projective-planar graphs containing no K33-subdivisions, we apply these
+techniques to obtain their unlabelled enumeration.",0509004v2
+2006-05-19,Deformation spaces of trees,"Let G be a finitely generated group. Two simplicial G-trees are said to be in
+the same deformation space if they have the same elliptic subgroups (if H fixes
+a point in one tree, it also does in the other). Examples include
+Culler-Vogtmann's outer space, and spaces of JSJ decompositions. We discuss
+what features are common to trees in a given deformation space, how to pass
+from one tree to all other trees in its deformation space, and the topology of
+deformation spaces. In particular, we prove that all deformation spaces are
+contractible complexes.",0605545v2
+1999-10-12,"Uniform spectral properties of one-dimensional quasicrystals, III. $α$-continuity","We study the spectral properties of discrete one-dimensional Schr\""odinger
+operators with Sturmian potentials. It is shown that the point spectrum is
+always empty. Moreover, for rotation numbers with bounded density, we establish
+purely $\alpha$-continuous spectrum, uniformly for all phases. The proofs rely
+on the unique decomposition property of Sturmian potentials, a
+mass-reproduction technique based upon a Gordon-type argument, and on the
+Jitomirskaya-Last extension of the Gilbert-Pearson theory of subordinacy.",9910017v1
+2003-08-18,Vector Coherent States on Clifford algebras,"The well-known canonical coherent states are expressed as an infinite series
+in powers of a complex number $z$ together with a positive sequence of real
+numbers $\rho(m)=m$. In this article, in analogy with the canonical coherent
+states, we present a class of vector coherent states by replacing the complex
+variable $z$ by a real Clifford matrix. We also present another class of vector
+coherent states by simultaneously replacing $z$ by a real Clifford matrix and
+$\rho(m)$ by a real matrix. As examples, we present vector coherent states on
+quaternions and octonions with their real matrix representations.",0308020v2
+2007-01-12,Non-equilibrium Lorentz gas on a curved space,"The periodic Lorentz gas with external field and iso-kinetic thermostat is
+equivalent, by conformal transformation, to a billiard with expanding
+phase-space and slightly distorted scatterers, for which the trajectories are
+straight lines. A further time rescaling allows to keep the speed constant in
+that new geometry. In the hyperbolic regime, the stationary state of this
+billiard is characterized by a phase-space contraction rate, equal to that of
+the iso-kinetic Lorentz gas. In contrast to the iso-kinetic Lorentz gas where
+phase-space contraction occurs in the bulk, the phase-space contraction rate
+here takes place at the periodic boundaries.",0701024v1
+2006-02-23,Equivalence of two mathematical forms for the bound angular momentum of the electromagnetic field,"It is shown that the mathematical form, obtained in a recent paper, for the
+angular momentum of the electromagnetic field in the vicinity of electric
+charge is equivalent to another form obtained previously by Cohen-Tannoudji,
+Dupont-Roc and Gilbert. In this version of the paper an improved derivation is
+given.",0602157v3
+2006-10-13,Senescence Can Explain Microbial Persistence,"It has been known for many years that small fractions of persister cells
+resist killing in many bacterial colony-antimicrobial confrontations. These
+persisters are not believed to be mutants. Rather it has been hypothesized that
+they are phenotypic variants. Current models allow cells to switch in and out
+of the persister phenotype. Here we suggest a different explanation, namely
+senescence, for persister formation. Using a mathematical model including age
+structure, we show that senescence provides a natural explanation for
+persister-related phenomena including the observations that persister fraction
+depends on growth phase in batch culture and dilution rate in continuous
+culture.",0610026v1
+2002-12-30,Dark propagation modes in optical lattices,"We examine the stimulated light scattering onto the propagation modes of a
+dissipative optical lattice. We show that two different pump-probe
+configurations may lead to the excitation, via different mechanisms, of the
+same mode. We found that in one configuration the scattering on the propagation
+mode results in a resonance in the probe transmission spectrum while in the
+other configuration no modification of the scattering spectrum occurs, i.e. the
+mode is dark. A theoretical explanation of this behaviour is provided.",0212157v1
+2003-09-29,Phase-control of directed diffusion in a symmetric optical lattice,"We demonstrate the phenomenon of directed diffusion in a symmetric periodic
+potential. This has been realized with cold atoms in a one-dimensional
+dissipative optical lattice. The stochastic process of optical pumping leads to
+a diffusive dynamics of the atoms through the periodic structure, while a
+zero-mean force which breaks the temporal symmetry of the system is applied by
+phase-modulating one of the lattice beams. The atoms are set into directed
+motion as a result of the breaking of the temporal symmetry of the system.",0309208v1
+2003-09-29,Synchronization of Hamiltonian motion and dissipative effects in optical lattices: Evidence for a stochastic resonance,"We theoretically study the influence of the noise strength on the excitation
+of the Brillouin propagation modes in a dissipative optical lattice. We show
+that the excitation has a resonant behavior for a specific amount of noise
+corresponding to the precise synchronization of the Hamiltonian motion on the
+optical potential surfaces and the dissipative effects associated with optical
+pumping in the lattice. This corresponds to the phenomenon of stochastic
+resonance. Our results are obtained by numerical simulations and correspond to
+the analysis of microscopic quantities (atomic spatial distributions) as well
+as macroscopic quantities (enhancement of spatial diffusion and pump-probe
+spectra). We also present a simple analytical model in excellent agreement with
+the simulations.",0309210v1
+2006-06-23,Playing Quantum Physics Jeopardy with zero-energy eigenstates,"We describe an example of an exact, quantitative Jeopardy-type quantum
+mechanics problem. This problem type is based on the conditions in
+one-dimensional quantum systems that allow an energy eigenstate for the
+infinite square well to have zero curvature and zero energy when suitable Dirac
+delta functions are added. This condition and its solution are not often
+discussed in quantum mechanics texts and have interesting pedagogical
+consequences.",0606196v1
+2006-10-18,Subsystem Codes,"We investigate various aspects of operator quantum error-correcting codes or,
+as we prefer to call them, subsystem codes. We give various methods to derive
+subsystem codes from classical codes. We give a proof for the existence of
+subsystem codes using a counting argument similar to the quantum
+Gilbert-Varshamov bound. We derive linear programming bounds and other upper
+bounds. We answer the question whether or not there exist
+[[n,n-2d+2,r>0,d]]<sub>q</sub> subsystem codes. Finally, we compare stabilizer
+and subsystem codes with respect to the required number of syndrome qudits.",0610153v1
+2007-05-14,The dynamical response to the node defect in thermally activated remagnetization of magnetic dot array,"The influence of nonmagnetic central node defect on dynamical properties of
+regular square-shaped 5 x 5 segment of magnetic dot array under the thermal
+activation is investigated via computer simulations. Using stochastic
+Landau-Lifshitz-Gilbert equation we simulate hysteresis and relaxation
+processes. The remarkable quantitative and qualitative differences between
+magnetic dot arrays with nonmagnetic central node defect and magnetic dot
+arrays without defects have been found.",0705.1889v1
+2007-05-18,Steady-state conduction in self-similar billiards,"The self-similar Lorentz billiard channel is a spatially extended
+deterministic dynamical system which consists of an infinite one-dimensional
+sequence of cells whose sizes increase monotonically according to their
+indices. This special geometry induces a nonequilibrium stationary state with
+particles flowing steadily from the small to the large scales. The
+corresponding invariant measure has fractal properties reflected by the
+phase-space contraction rate of the dynamics restricted to a single cell with
+appropriate boundary conditions. In the near-equilibrium limit, we find
+numerical agreement between this quantity and the entropy production rate as
+specified by thermodynamics.",0705.2758v1
+2007-06-04,Generation of microwave radiation in planar spin-transfer devices,"Current induced precession states in spin-transfer devices are studied in the
+case of large easy plane anisotropy (present in most experimental setups). It
+is shown that the effective one-dimensional planar description provides a
+simple qualitative understanding of the emergence and evolution of such states.
+Switching boundaries are found analytically for the collinear device and the
+spin-flip transistor. The latter can generate microwave oscillations at zero
+external magnetic field without either special functional form of spin-transfer
+torque, or ``field-like'' terms, if Gilbert constant corresponds to the
+overdamped planar regime.",0706.0529v1
+2007-12-26,Mass and angular-momentum inequalities for axi-symmetric initial data sets. II. Angular-momentum,"We extend the validity of Dain's angular-momentum inequality to maximal,
+asymptotically flat, initial data sets on a simply connected manifold with
+several asymptotically flat ends which are invariant under a U(1) action and
+which admit a twist potential.",0712.4064v2
+2008-01-28,TER: A Robot for Remote Ultrasonic Examination: Experimental Evaluations,"This chapter:
+  o Motivates the clinical use of robotic tele-echography
+  o Introduces the TER system
+  o Describes technical and clinical evaluations performed with TER",0801.4355v1
+2008-03-14,Spin-torque shot noise in magnetic tunnel junctions,"Spin polarized current may transfer angular momentum to a ferromagnet,
+resulting in a spin-torque phenomenon. At the same time the shot noise,
+associated with the current, leads to a non-equilibrium stochastic force acting
+on the ferromagnet. We derive stochastic version of Landau-Lifshitz-Gilbert
+equation for a magnetization of a ''free'' ferromagnetic layer in contact with
+a ''fixed'' ferromagnet. We solve the corresponding Fokker-Planck equation and
+show that the non-equilibrium noise yields to a non-monotonous dependence of
+the precession spectrum linewidth on the current.",0803.2101v1
+2008-04-07,Paired Orbitals for Different Spins equations,"Eigenvalue-type equations for Lowdin-Amos-Hall spin-paired (corresponding)
+orbitals are developed to provide an alternative to the standard spin-polarized
+Hartree-Fock or Kohn-Sham equations. Obtained equations are non-canonical
+unrestricted Hartree-Fock-type equations in which non-canonical orbitals are
+fixed to be biorthogonal spin-paired orbitals. To derive paired orbitals for
+different spins (PODS) equations there has been applied Adams-Gilbert
+localizing operator approach. PODS equations are especially useful for
+treatment of the broken-symmetry solutions for antiferromagnetic materials.",0804.0967v1
+2008-04-26,Spin-torque oscillator based on tilted magnetization of the fixed layer,"The spin torque oscillator (STO), where the magnetization of the fixed layer
+is tilted out of the film plane, is capable of strong microwave signal
+generation in zero magnetic field. Through numerical simulations of the
+Landau-Lifshitz-Gilbert-Slonczewski equations, within a macro-spin
+approximation, we study the microwave signal generation as a function of drive
+current for two realistic tilt angles. The tilt magnetization of the fixed
+layer can be achieved by using a material with high out-of-plane
+magnetocrystalline anisotropy, such as L10 FePt.",0804.4213v1
+2008-07-11,Superconductivity up to 29 K in SrFe2As2 and BaFe2As2 at high pressures,"We report the discovery of superconductivity at high pressure in SrFe2As2 and
+BaFe2As2. The superconducting transition temperatures are up to 27 K in
+SrFe2As2 and 29 K in BaFe2As2, making these the highest pressure-induced
+superconducting materials discovered thus far.",0807.1896v2
+2008-07-14,An Adaptive Entanglement Distillation Scheme Using Quantum Low Density Parity Check Codes,"Quantum low density parity check (QLDPC) codes are useful primitives for
+quantum information processing because they can be encoded and decoded
+efficiently. Besides, the error correcting capability of a few QLDPC codes
+exceeds the quantum Gilbert-Varshamov bound. Here, we report a numerical
+performance analysis of an adaptive entanglement distillation scheme using
+QLDPC codes. In particular, we find that the expected yield of our adaptive
+distillation scheme to combat depolarization errors exceed that of Leung and
+Shor whenever the error probability is less than about 0.07 or greater than
+about 0.28. This finding illustrates the effectiveness of using QLDPC codes in
+entanglement distillation.",0807.2122v1
+2008-07-16,Analytical solution of the equation of motion for a rigid domain wall in a magnetic material with perpendicular anisotropy,"This paper reports the solution of the equation of motion for a domain wall
+in a magnetic material which exhibits high magneto-crystalline anisotropy.
+Starting from the Landau-Lifschitz-Gilbert equation for field-induced motion,
+we solve the equation to give an analytical expression, which specifies the
+domain wall position as a function of time. Taking parameters from a Co/Pt
+multilayer system, we find good quantitative agreement between calculated and
+experimentally determined wall velocities, and show that high field uniform
+wall motion occurs when wall rigidity is assumed.",0807.2604v3
+2008-07-16,A graphical extension for the Windows version of the Parallel Finite Element Micromagnetics Package (MagParExt),"In the current paper we present a graphical user interface useful for
+settings input parameter of the Windows precompiled binaries for the Parallel
+Finite Element Micromagnetics Package (MagPar). The Package is used for
+magnetization dynamics analysis on a base of the Landau-Lifshitz-Gilbert (LLG)
+equation. In an available version of the MagPar package there are several text
+files which control simulations. Presented here graphical extension (MagParExt)
+enables easy preparation of input and output data, stored in text files, and
+additionally, direct and fast creation of figures obtained from dependencies
+between simulated physical quantities.",0807.2655v1
+2008-08-17,Attempt frequency of magnetization in nanomagnets with thin-film geometry,"Solving the stochastic Landau-Lifshitz-Gilbert equation numerically, we
+investigate the effect of the potential landscape on the attempt frequency of
+magnetization in nanomagnets with the thin-film geometry. Numerical estimates
+of the attempt frequency are analyzed in comparison with theoretical
+predictions from the Fokker-Planck equation for the Neel-Brown model. It is
+found that for a nanomagnet with the thin-film geometry, theoretically
+predicted values for the universal case are in excellent agreement with
+numerical estimates.",0808.2281v1
+2008-08-30,Path integral study of the role of correlation in exchange coupling of spins in double quantum dots and optical lattices,"We explore exchange coupling of a pair of spins in a double dot and in an
+optical lattice. Our algorithm uses the frequency of exchanges in a bosonic
+path integral, evaluated with Monte Carlo. This algorithm is simple enough to
+be a ""black box"" calculator, yet gives insights into the role of correlation
+through two-particle probability densities, visualization of instantons, and
+pair correlation functions. We map the problem to Hubbard model and see that
+exchange and correlation renormalize the effective parameters, dramatically
+lowering U at larger separations.",0809.0038v1
+2008-09-16,Stochastic dynamics of magnetization in a ferromagnetic nanoparticle out of equilibrium,"We consider a small metallic particle (quantum dot) where ferromagnetism
+arises as a consequence of Stoner instability. When the particle is connected
+to electrodes, exchange of electrons between the particle and the electrodes
+leads to a temperature- and bias-driven Brownian motion of the direction of the
+particle magnetization. Under certain conditions this Brownian motion is
+described by the stochastic Landau-Lifshitz-Gilbert equation. As an example of
+its application, we calculate the frequency-dependent magnetic susceptibility
+of the particle in a constant external magnetic field, which is relevant for
+ferromagnetic resonance measurements.",0809.2611v1
+2008-12-09,On densest packings of equal balls of $\rb^{n}$ and Marcinkiewicz spaces,"We investigate, by ""a la Marcinkiewicz"" techniques applied to the
+(asymptotic) density function, how dense systems of equal spheres of $\rb^{n},
+n \geq 1,$ can be partitioned at infinity in order to allow the computation of
+their density as a true limit and not a limsup. The density of a packing of
+equal balls is the norm 1 of the characteristic function of the systems of
+balls in the sense of Marcinkiewicz. Existence Theorems for densest sphere
+packings and completely saturated sphere packings of maximal density are given
+new direct proofs.",0812.1720v1
+2009-01-26,Bioprotectant glassforming solutions confined in porous silicon nanocapillaries,"Glycerol and trehalose-glycerol binary solutions are glass-forming liquids
+with remarkable bioprotectant properties. In this paper, we address the effects
+of confining of these solutions in straight channels of diameter D=8 nm formed
+by porous silicon. Neutron diffraction and incoherent quasielastic neutron
+scattering are used to reveal the different effects of nanoconfinement and
+addition of trehalose on the intermolecular structure and molecular dynamics of
+the liquid and glassy phases, on a nanosecond timescale.",0901.3994v1
+2009-02-12,Computing equations for residually free groups,"We show that there is no algorithm deciding whether the maximal residually
+free quotient of a given finitely presented group is finitely presentable or
+not.
+  Given a finitely generated subgroup G of a finite product of limit groups, we
+discuss the possibility of finding an explicit set of defining equations (i.e.
+of expressing G as the maximal residually free quotient of an explicit finitely
+presented group).",0902.2119v2
+2009-03-06,Simulation of current-induced microwave oscillation in geometrically confined domain wall,"We studied magnetization dynamics of a geometrically confined domain wall
+under dc current by solving simultaneously the Landau-Lifshitz-Gilbert equation
+and diffusion equation for spin accumulation. We showed that the oscillation
+motion of the domain wall is driven by the spin-transfer torque and the dc
+current is converted to the ac voltage signal. The results means that the
+geometrically confined domain wall is applicable as a source of microwave
+oscillator.",0903.1151v1
+2009-04-05,Projective Space Codes for the Injection Metric,"In the context of error control in random linear network coding, it is useful
+to construct codes that comprise well-separated collections of subspaces of a
+vector space over a finite field. In this paper, the metric used is the
+so-called ""injection distance"", introduced by Silva and Kschischang. A
+Gilbert-Varshamov bound for such codes is derived. Using the code-construction
+framework of Etzion and Silberstein, new non-constant-dimension codes are
+constructed; these codes contain more codewords than comparable codes designed
+for the subspace metric.",0904.0813v2
+2009-05-28,Hamilton cycles in random geometric graphs,"We prove that, in the Gilbert model for a random geometric graph, almost
+every graph becomes Hamiltonian exactly when it first becomes 2-connected. This
+answers a question of Penrose. We also show that in the k-nearest neighbor
+model, there is a constant \kappa\ such that almost every \kappa-connected
+graph has a Hamilton cycle.",0905.4650v2
+2009-06-25,Nonlinear Schroedinger-Poisson Theory for Quantum-Dot Helium,"We use a nonlinear Schroedinger-Poisson equation to describe two interacting
+electrons with opposite spins confined in a parabolic potential, a quantum dot.
+We propose an effective form of the Poisson equation taking into account the
+dimensional mismatch of the two-dimensional electronic system and the
+three-dimensional electrostatics. The results agree with earlier numerical
+calculations performed in a large basis of two-body states and provide a simple
+model for continuous quantum-classical transition with increasing nonlinearity.
+Specific intriguing properties due to eigenstate non-orthogonality are
+emphasized.",0906.4650v1
+2009-06-29,Performance of Magnetic Quantum Cellular Automata and Limitations due to Thermal Noise,"Operation parameters of magnetic quantum cellular automata are evaluated for
+the purposes of reliable logic operation. The dynamics of the nanomagnets is
+simulated via the Landau-Lifshitz-Gilbert equations with a stochastic magnetic
+field corresponding to thermal fluctuations. It is found that in the macrospin
+approximation the switching speed does not change under scaling of both size
+and distances between nanomagnets. Thermal fluctuations put a limitation on the
+size of nanomagnets, since the gate error rate becomes excessive for
+nanomagnets smaller than 200nm at room temperature.",0906.5172v1
+2009-09-15,Critical current density for spin transfer torque switching with composite free layer structure,"Critical current density of composite free layer (CFL) in magnetic tunneling
+junction is investigated. CFL consists of two exchange coupled ferromagnetic
+layers, where the coupling is parallel or anti-parallel. Instability condition
+of the CFL under the spin transfer torque, which is related with critical
+current density, is obtained by analytic spin wave excitation model and
+confirmed by macro-spin Landau-Lifshitz-Gilbert equation. The critical current
+densities for the coupled two identical layers are investigated with various
+coupling strengths, and spin transfer torque efficiencies.",0909.2711v1
+2009-09-25,Tunable steady-state domain wall oscillator with perpendicular magnetic anisotropy,"We theoretically study domain wall oscillations upon the injection of a dc
+current through a geometrically constrained wire with perpendicular magnetic
+anisotropy. The oscillation frequency spectrum can be tuned by the injected
+current density, but additionally by the application of an external magnetic
+field independent of the power. The results of analytical calculations are
+supported by micromagnetic simulations based on the Landau-Lifshitz-Gilbert
+equation. The simple concept of our localized steady-state oscillator might
+prove useful as a nanoscale microwave generator with possible applications in
+telecommunication or for rf-assisted writing in magnetic hard drives.",0909.4733v1
+2009-10-13,Dipolar field effect on microwave oscillation in a domain wall spin-valve,"We examined dipolar field effects on the microwave generation in the domain
+wall spin-valve by solving simultaneously the Landau-Lifshitz-Gilbert and
+Zhang-Levy-Fert diffusion equations. By numerically analyzing dipolar field
+dependence, we showed that the microwave generation needs the dipole-dipole
+interaction for a 180$^\circ$ domain wall and the amplitude of the microwave
+voltage signal depends strongly on the exchange length. In order to design a
+microwave generator using the domain wall spin-valve with high efficiency, we
+propose that the materials with short exchange length are preferred.",0910.2280v1
+2009-10-30,Dissipative dynamics of magnetic solitons in metals,"Soliton dynamics in spin-textured metals generate electrical currents, which
+produce backaction through spin torques. We modify the Landau-Lifshitz-Gilbert
+equation and the corresponding solitonic equations of motion to include such
+higher-order texture effects. We also find a quasistatic equation for the
+induced electrochemical potential, which needs to be solved for
+self-consistently, in the incompressible limit. As an example, we consider the
+orbital motion of a vortex in a point-contact spin valve, and discuss
+modifications of orbit radius, frequency, and dissipation power.",0910.5912v2
+2009-11-16,"JSJ decompositions: definitions, existence, uniqueness. I: The JSJ deformation space","This paper and its companion arXiv:1002.4564 have been replaced by
+arXiv:1602.05139.
+  We give a general simple definition of JSJ decompositions by means of a
+universal maximality property. The JSJ decomposition should not be viewed as a
+tree (which is not uniquely defined) but as a canonical deformation space of
+trees. We prove that JSJ decompositions of finitely presented groups always
+exist, without any assumption on edge groups. Many examples are given.",0911.3173v3
+2010-02-15,Domain wall motion in ferromagnetic nanowires driven by arbitrary time-dependent fields: An exact result,"We address the dynamics of magnetic domain walls in ferromagnetic nanowires
+under the influence of external time-dependent magnetic fields. We report a new
+exact spatiotemporal solution of the Landau-Lifshitz-Gilbert equation for the
+case of soft ferromagnetic wires and nanostructures with uniaxial anisotropy.
+The solution holds for applied fields with arbitrary strength and time
+dependence. We further extend this solution to applied fields slowly varying in
+space and to multiple domain walls.",1002.2913v1
+2010-05-24,SN2010U -- a Luminous Nova in NGC 4214,"The luminosity, light curve, post--maximum spectrum, and lack of a progenitor
+on deep pre-outburst images suggest that SN 2010U was a luminous, fast nova.
+Its outburst magnitude is consistent with that for a fast nova using the
+Maximum Magnitude-Rate of Decline relationship for classical novae.",1005.4356v1
+2010-06-11,Highly Parallel Sparse Matrix-Matrix Multiplication,"Generalized sparse matrix-matrix multiplication is a key primitive for many
+high performance graph algorithms as well as some linear solvers such as
+multigrid. We present the first parallel algorithms that achieve increasing
+speedups for an unbounded number of processors. Our algorithms are based on
+two-dimensional block distribution of sparse matrices where serial sections use
+a novel hypersparse kernel for scalability. We give a state-of-the-art MPI
+implementation of one of our algorithms. Our experiments show scaling up to
+thousands of processors on a variety of test scenarios.",1006.2183v1
+2010-06-24,Boundary regularity for minimizers of the micromagnetic energy functional,"Motivated by the construction of time-periodic solutions for the
+three-dimensional Landau-Lifshitz-Gilbert equation in the case of soft and
+small ferromagnetic particles, we investigate the regularity properties of
+minimizers of the micromagnetic energy functional at the boundary. In
+particular, we show that minimizers are regular provided the volume of the
+particle is sufficiently small. The approach uses a reflection construction at
+the boundary and an adaption of the well-known regularity theory for minimizing
+harmonic maps into spheres.",1006.4766v1
+2010-06-24,Time-periodic Néel wall motions,"In thin ferromagnetic films, the predominance of the magnetic shape
+anisotropy leads to in-plane magnetizations. The simplest domain wall in this
+geometry is the one-dimensional Neel wall that connects two magnetizations of
+opposite sign by a planar 180 degree rotation. In this paper, we perturb the
+static Neel wall profile in order to construct time-periodic Neel wall motions
+governed by to the Landau-Lifshitz-Gilbert equation. Our construction works
+within a certain parameter regime and requires the restriction to external
+magnetic fields with small amplitudes and suitable time averages.",1006.4768v1
+2010-06-30,Supercurrent-Induced Magnetization Dynamics,"We investigate supercurrent-induced magnetization dynamics in a Josephson
+junction with two misaligned ferromagnetic layers, and demonstrate a variety of
+effects by solving numerically the Landau-Lifshitz-Gilbert equation. In
+particular, we demonstrate the possibility to obtain supercurrent-induced
+magnetization switching for an experimentally feasible set of parameters, and
+clarify the favorable condition for the realization of magnetization reversal.
+These results constitute a superconducting analogue to conventional
+current-induced magnetization dynamics and indicate how spin-triplet
+supercurrents may be utilized for practical purposes in spintronics.",1007.0004v1
+2010-07-09,Polarization and magnetization dynamics of a field-driven multiferroic structure,"We consider a multiferroic chain with a linear magnetoelectric coupling
+induced by the electrostatic screening at the ferroelectric/ferromagnet
+interface. We study theoretically the dynamic ferroelectric and magnetic
+response to external magnetic and electric fields by utilizing an approach
+based on coupled Landau- Khalatnikov and finite-temperature
+Landau-Lifshitz-Gilbert equations. Additionally, we compare with Monte Carlo
+calculations. It is demonstrated that for material parameters corresponding to
+BaTiO3/Fe the polarization and the magnetization are controllable by external
+magnetic and electric fields respectively.",1007.1543v1
+2010-07-11,Factorization of banded permutations,"We consider the factorization of permutations into bandwidth 1 permutations,
+which are products of mutually nonadjacent simple transpositions. We exhibit an
+upper bound on the minimal number of such factors and thus prove a conjecture
+of Gilbert Strang: a banded permutation of bandwidth $w$ can be represented as
+the product of at most $2w-1$ permutations of bandwidth 1. An analogous result
+holds also for infinite and cyclically banded permutations.",1007.1760v2
+2010-07-14,Nonlinear interference in a mean-field quantum model,"Using similar nonlinear stationary mean-field models for Bose-Einstein
+Condensation of cold atoms and interacting electrons in a Quantum Dot, we
+propose to describe the original many-particle ground state as a one-particle
+statistical mixed state of the nonlinear eigenstates whose weights are provided
+by the eigenstate non-orthogonality. We search for physical grounds in the
+interpretation of our two main results, namely, quantum-classical nonlinear
+transition and interference between nonlinear eigenstates.",1007.2408v1
+2011-01-17,Steiner Ratio for Manifolds,"The Steiner ratio characterizes the greatest possible deviation of the length
+of a minimal spanning tree from the length of the minimal Steiner tree. In this
+paper, estimates of the Steiner ratio on Riemannian manifolds are obtained. As
+a corollary, the Steiner ratio for flat tori, flat Klein bottles, and
+projective plane of constant positive curvature are computed. Steiner ratio -
+Steiner problem - Gilbert--Pollack conjecture - surfaces of constant curvature",1101.3144v1
+2011-02-04,Current-induced dynamics of composite free layer with antiferromagnetic interlayer exchange coupling,"Current-induced dynamics in spin valves including composite free layer with
+antiferromagnetic interlayer exchange coupling is studied theoretically within
+the diffusive transport regime. We show that current-induced dynamics of a
+synthetic antiferromagnet is significantly different from dynamics of a
+synthetic ferrimagnet. From macrospin simulations we obtain conditions for
+switching the composite free layer, as well as for appearance of various
+self-sustained dynamical modes. Numerical simulations are compared with simple
+analytical models of critical current based on linearized
+Landau-Lifshitz-Gilbert equation.",1102.1028v2
+2011-04-01,Spin waves cause non-linear friction,"Energy dissipation is studied for a hard magnetic tip that scans a soft
+magnetic substrate. The dynamics of the atomic moments are simulated by solving
+the Landau-Lifshitz-Gilbert (LLG) equation numerically. The local energy
+currents are analysed for the case of a Heisenberg spin chain taken as
+substrate. This leads to an explanation for the velocity dependence of the
+friction force: The non-linear contribution for high velocities can be
+attributed to a spin wave front pushed by the tip along the substrate.",1104.0197v2
+2011-05-31,Upper and Lower Bounds on the Minimum Distance of Expander Codes,"The minimum distance of expander codes over GF(q) is studied. A new upper
+bound on the minimum distance of expander codes is derived. The bound is shown
+to lie under the Varshamov-Gilbert (VG) bound while q >= 32. Lower bounds on
+the minimum distance of some families of expander codes are obtained. A lower
+bound on the minimum distance of low-density parity-check (LDPC) codes with a
+Reed--Solomon constituent code over GF(q) is obtained. The bound is shown to be
+very close to the VG bound and to lie above the upper bound for expander codes.",1105.6224v1
+2011-06-28,Stability of precessing domain walls in ferromagnetic nanowires,"We show that recently reported precessing solution of Landau-Lifshitz-Gilbert
+equations in ferromagnetic nanowires is stable under small perturbations of
+initial data, applied field and anisotropy constant. Linear stability is
+established analytically, while nonlinear stability is verified numerically.",1106.5808v2
+2011-07-01,Current induced magnetization reversal on the surface of a topological insulator,"We study dynamics of the magnetization coupled to the surface Dirac fermions
+of a three di- mensional topological insulator. By solving the
+Landau-Lifshitz-Gilbert equation in the presence of charge current, we find
+current induced magnetization dynamics and discuss the possibility of mag-
+netization reversal. The torque from the current injection depends on the
+transmission probability through the ferromagnet and shows nontrivial
+dependence on the exchange coupling. The mag- netization dynamics is a direct
+manifestation of the inverse spin-galvanic effect and hence another ferromagnet
+is unnecessary to induce spin transfer torque in contrast to the conventional
+setup.",1107.0116v1
+2011-08-05,Thermoelectric detection of ferromagnetic resonance of a nanoscale ferromagnet,"We present thermoelectric measurements of the heat dissipated due to
+ferromagnetic resonance of a Permalloy strip. A microwave magnetic field,
+produced by an on-chip coplanar strip waveguide, is used to drive the
+magnetization precession. The generated heat is detected via Seebeck
+measurements on a thermocouple connected to the ferromagnet. The observed
+resonance peak shape is in agreement with the Landau-Lifshitz-Gilbert equation
+and is compared with thermoelectric finite element modeling. Unlike other
+methods, this technique is not restricted to electrically conductive media and
+is therefore also applicable to for instance ferromagnetic insulators.",1108.1286v1
+2011-08-31,Effects of Fermion Flavor on Exciton Condensation in Double Layer Systems,"We use fermionic path integral quantum Monte Carlo to study the effects of
+fermion flavor on the physical properties of dipolar exciton condensates in
+double layer systems. We find that by including spin in the system weakens the
+effective interlayer interaction strength, yet this has very little effect on
+the Kosterlitz-Thouless transition temperature. We further find that, to obtain
+the correct description of screening, it is necessary to account for
+correlation in both the interlayer and intralayer interactions. We show that
+while the excitonic binding cannot completely surpress screening by additional
+fermion flavors, their screening effectiveness is reduced leading to a much
+higher transition temperatures than predicted with large-N analysis.",1108.6107v1
+2011-09-30,An ultrafast image recovery and recognition system implemented with nanomagnets possessing biaxial magnetocrystalline anisotropy,"A circular magnetic disk with biaxial magnetocrystalline anisotropy has four
+stable magnetization states which can be used to encode a pixel's shade in a
+black/gray/white image. By solving the Landau-Lifshitz- Gilbert equation, we
+show that if moderate noise deflects the magnetization slightly from a stable
+state, it always returns to the original state, thereby automatically
+de-noising the corrupted image. The same system can compare a noisy input image
+with a stored image and make a matching decision using magneto-tunneling
+junctions. These tasks are executed at ultrahigh speeds (~2 ns for a
+512\times512 pixel image).",1109.6932v1
+2011-11-10,Magnonic band structure of a two-dimensional magnetic superlattice,"The frequencies and linewidths of spin waves in a two-dimensional periodic
+superlattice of magnetic materials are found, using the Landau-Lifshitz-Gilbert
+equations. The form of the exchange field from a surface-torque-free boundary
+between magnetic materials is derived, and magnetic-material combinations are
+identified which produce gaps in the magnonic spectrum across the entire
+superlattice Brillouin zone for hexagonal and square-symmetry superlattices.",1111.2506v1
+2011-11-29,Supercurrent induced domain wall motion,"We study the dynamics of a magnetic domain wall, inserted in, or juxtaposed
+to, a conventional superconductor, via the passage of a spin polarized current
+through a FSF junction. Solving the Landau-Lifshitz-Gilbert equation of motion
+for the magnetic moments we calculate the velocity of the domain wall and
+compare it with the case of a FNF junction. We find that in several regimes the
+domain wall velocity is larger when it is driven by a supercurrent.",1111.6751v1
+2011-12-02,The Main Diagonal of a Permutation Matrix,"By counting 1's in the ""right half"" of $2w$ consecutive rows, we locate the
+main diagonal of any doubly infinite permutation matrix with bandwidth $w$.
+Then the matrix can be correctly centered and factored into block-diagonal
+permutation matrices. Part II of the paper discusses the same questions for the
+much larger class of band-dominated matrices. The main diagonal is determined
+by the Fredholm index of a singly infinite submatrix. Thus the main diagonal is
+determined ""at infinity"" in general, but from only $2w$ rows for banded
+permutations.",1112.0582v2
+2011-12-11,Stability of the Greedy Algorithm on the Circle,"We consider a single-server system with service stations in each point of the
+circle. Customers arrive after exponential times at uniformly-distributed
+locations. The server moves at finite speed and adopts a greedy routing
+mechanism. It was conjectured by Coffman and Gilbert in~1987 that the service
+rate exceeding the arrival rate is a sufficient condition for the system to be
+positive recurrent, for any value of the speed. In this paper we show that the
+conjecture holds true.",1112.2389v3
+2011-12-12,Riffle shuffles with biased cuts,"The well-known Gilbert-Shannon-Reeds model for riffle shuffles assumes that
+the cards are initially cut 'about in half' and then riffled together. We
+analyze a natural variant where the initial cut is biased. Extending results of
+Fulman (1998), we show a sharp cutoff in separation and L-infinity distances.
+This analysis is possible due to the close connection between shuffling and
+quasisymmetric functions along with some complex analysis of a generating
+function.",1112.2650v1
+2011-12-15,Solutions of the Fully Compressible Semi-Geostrophic System,"The fully compressible semi-geostrophic system is widely used in the
+modelling of large-scale atmospheric flows. In this paper, we prove rigorously
+the existence of weak Lagrangian solutions of this system, formulated in the
+original physical coordinates. In addition, we provide an alternative proof of
+the earlier result on the existence of weak solutions of this system expressed
+in the so-called geostrophic, or dual, coordinates. The proofs are based on the
+optimal transport formulation of the problem and on recent general results
+concerning transport problems posed in the Wasserstein space of probability
+measures.",1112.3553v2
+2012-01-23,Micromagnetic Simulations for Spin Transfer Torque in Magnetic Multilayers,"We investigate the spin transfer torque (STT) in the magnetic multilayer
+structures with micromagnetic simulations. We implement the STT contribution
+for the magnetic multilayer structures in addition to the
+Landau-Lifshitz-Gilbert (LLG) micromagnetic simulators. Not only the Sloncewski
+STT term, the zero, first, and second order field- like terms are also
+considered, and the effects of the Oersted field by the current are addressed.
+We determine the switching current densities of the free layer with the
+exchange biased synthetic ferrimagnetic reference layers for various cases.",1201.4707v1
+2012-01-26,Pseudospin Transfer Torques in Semiconductor Electron Bilayers,"We use self-consistent quantum transport theory to investigate the influence
+of electron-electron interactions on interlayer transport in semiconductor
+electron bilayers in the absence of an external magnetic field. We conclude
+that, even though spontaneous pseudospin order does not occur at zero field,
+interaction-enhanced quasiparticle tunneling amplitudes and pseudospin transfer
+torques do alter tunneling I-V characteristics, and can lead to time-dependent
+response to a dc bias voltage.",1201.5569v2
+2012-03-03,Skyrmion Generation by Current,"Skyrmions, once a hypothesized field-theoretical object believed to describe
+the nature of elementary particles, became common sightings in recent years
+among several non-centrosymmetric metallic ferromagnets. For more practical
+applications of Skyrmionic matter as carriers of information, thus realizing
+the prospect of ""Skyrmionics"", it is necessary to have the means to create and
+manipulate Skyrmions individually. We show through extensive simulation of the
+Landau-Lifshitz-Gilbert equation that a circulating current imparted to the
+metallic chiral ferromagnetic system can create isolated Skyrmionic spin
+texture without the aid of external magnetic field.",1203.0638v1
+2012-04-25,Numerical Study on Spin Torque Switching in Thermally Activated Region,"We studied the spin torque switching of the single free layer in the
+thermally activated region by numerically solving the Landau-Lifshitz-Gilbert
+equation. We found that the temperature dependence of the switching time of the
+in-plane magnetized system is nonlinear, which means $b \neq 1$. Here, $b$ is
+the exponent of the current term in the switching rate formula and has been
+widely assumed to be unity. This result enables us to evaluate the thermal
+stability of spintronics devices.",1204.5596v2
+2012-07-13,Theory of current-driven motion of Skyrmions and spirals in helical magnets,"We study theoretically the dynamics of the spin textures, i.e., Skyrmion
+crystal (SkX) and spiral structure (SS), in two-dimensional helical magnets
+under external current. By numerically solving the Landau-Lifshitz-Gilbert
+equation, it is found that (i) the critical current density of the motion is
+much lower for SkX compared with SS in agreement with the recent experiment,
+(ii) there is no intrinsic pinning effect for SkX and the deformation of the
+internal structure of Skyrmion reduces the pinning effect dramatically, (iii)
+the Bragg intensity of SkX shows strong time-dependence as can be observed by
+neutron scattering experiment.",1207.3224v1
+2012-07-19,Solar Orbiter: Exploring the Sun-heliosphere connection,"The heliosphere represents a uniquely accessible domain of space, where
+fundamental physical processes common to solar, astrophysical and laboratory
+plasmas can be studied under conditions impossible to reproduce on Earth and
+unfeasible to observe from astronomical distances. Solar Orbiter, the first
+mission of ESA's Cosmic Vision 2015-2025 programme, will address the central
+question of heliophysics: How does the Sun create and control the heliosphere?
+In this paper, we present the scientific goals of the mission and provide an
+overview of the mission implementation.",1207.4579v2
+2012-07-19,Harnessing the modulation instability spectrum in optical fibers with a periodic dispersion landscape,"We report the experimental demonstration of modulation instability process
+assisted by a dispersion grating in an optical fiber. A simple analytical model
+is developed to further analyze and explain the complex dynamics of this
+process, showing that each of the multiple spectral components grows thanks to
+a quasi phase-matching mechanism inherent to the periodicity of the waveguide
+parameters. This model is confirmed by numerical simulations and it is
+successfully used to tailor the multi-peak modulation instability spectrum
+shape. These theoretical predictions are confirmed by experiments.",1207.4667v1
+2012-08-11,Lexicodes over Rings,"In this paper, we consider the construction of linear lexicodes over finite
+chain rings by using a $B$-ordering over these rings and a selection criterion.
+% and a greedy Algorithm. As examples we give lexicodes over $\mathbb{Z}_4$ and
+$\mathbb{F}_2+u\mathbb{F}_2$. %First, greedy algorithms are presented to
+construct %lexicodes using a multiplicative property. Then, greedy algorithms
+%are given for the case when the selection criteria is not %multiplicative such
+as the minimum distance constraint. It is shown that this construction produces
+many optimal codes over rings and also good binary codes. Some of these codes
+meet the Gilbert bound. We also obtain optimal self-dual codes, in particular
+the octacode.",1208.2361v2
+2012-09-07,Self-sustained current oscillations in spin-blockaded quantum dots,"Self-sustained current oscillation observed in spin-blockaded double quantum
+dots is explained as a consequence of periodic motion of dynamically polarized
+nuclear spins (along a limit cycle) in the spin-blockaded regime under an
+external magnetic field and a spin-transfer torque. It is shown, based on the
+Landau-Lifshtz-Gilbert equation, that a sequence of semistable limit cycle,
+Hopf and homoclinic bifurcations occurs as the external field is tuned. The
+divergent period near the homoclinic bifurcation explains well why the period
+in the experiment is so long and varies by many orders of magnitudes.",1209.1548v1
+2012-10-04,All Spin Nano-magnetic State Elements,"We propose an all spin state element to enable all spin state machines using
+spin currents and nanomagnets. We demonstrate via numerical simulations the
+operation of a state element a critical building block for synchronous,
+sequential logic computation. The numerical models encompass
+Landau-Lifshitz-Gilbert (LLG) nanomagnet dynamics with stochastic models and
+vector spin-transport in metallic magnetic and non-magnetic channels. Combined
+with all spin combinatorial logic, the state elements can enable synchronous
+and asynchronous computing elements.",1210.1613v1
+2012-11-02,Effect of Spin Torque on Magnetization Switching Speed Having Nonuniform Spin Distribution,"We study the influence of the spin torque, which depends on the space and
+time derivative of magnetization, on magnetization reversal time in a
+ferromagnetic fine particle. The spin torque operates to dissipate the angular
+momentum of the magnetization precession, and the torque increases in a spin
+vortex structure. We calculate the magnetization reversal time under a DC
+magnetic field using the Landau-Lifshitz-Gilbert equation containing a spin
+torque term. We found that the spin torque changes the magnetization switching
+speed significantly during the reversal process by maintaining a spin vortex in
+an intermediate state.",1211.0360v1
+2013-01-14,magnum.fe: A micromagnetic finite-element simulation code based on FEniCS,"We have developed a finite-element micromagnetic simulation code based on the
+FEniCS package called magnum.fe. Here we describe the numerical methods that
+are applied as well as their implementation with FEniCS. We apply a
+transformation method for the solution of the demagnetization-field problem. A
+semi-implicit weak formulation is used for the integration of the
+Landau-Lifshitz-Gilbert equation. Numerical experiments show the validity of
+simulation results. magnum.fe is open source and well documented. The broad
+feature range of the FEniCS package makes magnum.fe a good choice for the
+implementation of novel micromagnetic finite-element algorithms.",1301.3061v2
+2013-02-04,Control of dissipation in superconducting films by magnetic stray fields,"Hybrid superconducting/magnetic nanostructures on Si substrates have been
+built with identical physical dimensions but different magnetic configurations.
+By constructing arrays based on Co-dots with in-plane, out-of-plane, and vortex
+state magnetic configurations, the stray fields are systematically tuned.
+Dissipation in the mixed state of superconductors can be decreased (increased)
+by several orders of magnitude by decreasing (increasing) the stray magnetic
+fields. Furthermore, ordering of the stray fields over the entire array helps
+to suppress dissipation and enhance commensurability effects increasing the
+number of dissipation minima.",1302.0680v1
+2013-02-09,Lower bounds on the minimum distance of long codes in the Lee metric,"The Gilbert type bound for codes in the title is reviewed, both for small and
+large alphabets. Constructive lower bounds better than these existential bounds
+are derived from geometric codes, either over Fp or Fp2 ; or over even degree
+extensions of Fp: In the latter case the approach is concatena- tion with a
+good code for the Hamming metric as outer code and a short code for the Lee
+metric as an inner code. In the former case lower bounds on the minimum Lee
+distance are derived by algebraic geometric arguments inspired by results of
+Wu, Kuijper, Udaya (2007).",1302.2246v1
+2013-03-04,Mansuripur's Paradox,"A recent article claims that the Lorentz force law is incompatible with
+special relativity. We discuss the ""paradox"" on which this claim is based. The
+resolution depends on whether one assumes a ""Gilbert"" model for the magnetic
+dipole (separated monopoles) or the standard ""Ampere"" model (current loop). The
+former was presented in these pages many years ago; the latter requires the
+inclusion of ""hidden momentum.""",1303.0732v2
+2013-04-09,Instability of Walker Propagating Domain Wall in Magnetic Nanowires,"Stability of the well-known Walker propagating domain wall (DW) solution of
+the Landau-Lifshitz-Gilbert equation is analytically investigated.
+Surprisingly, the Walker's rigid body propagating DW mode is not stable against
+the spin wave/wavepacket emission. In the low field region only stern spin
+waves are emitted while both stern and bow waves are generated under high
+fields. In a high enough field, but below the Walker breakdown field, the
+Walker solution could be convective/absolute unstable if the transverse
+magnetic anisotropy is larger than a critical value, corresponding to a
+significant modification of the DW profile and DW propagating speed.",1304.2439v1
+2013-04-26,Maximizing Spin Torque Diode Voltage by Optimizing Magnetization Alignment,"The optimum condition of the magnetization alignment to maximize the spin
+torque diode voltage is derived by solving the Landau-Lifshitz-Gilbert
+equation. We show that the optimized diode voltage can be one order of
+magnitude larger than that of the conventional alignment where the easy axes of
+the free and the pinned layers are parallel. These analytical predictions are
+confirmed by numerical simulations.",1304.7079v1
+2013-05-23,Residual properties of automorphism groups of (relatively) hyperbolic groups,"We show that Out(G) is residually finite if G is a one-ended group that is
+hyperbolic relative to virtually polycyclic subgroups. More generally, if G is
+one-ended and hyperbolic relative to proper residually finite subgroups, the
+group of outer automorphisms preserving the peripheral structure is residually
+finite. We also show that Out(G) is virtually p-residually finite for every
+prime p if G is one-ended and toral relatively hyperbolic, or infinitely-ended
+and virtually p-residually finite.",1305.5403v3
+2013-05-25,Thermally-Assisted Spin-Transfer Torque Dynamics in Energy Space,"We consider the general Landau-Lifshitz-Gilbert theory underlying the
+magnetization dynamics of a macrospin magnet subject to spin-torque effects and
+thermal fluctuations. Thermally activated dynamical properties are analyzed by
+averaging the full magnetization equations over constant- energy orbits. After
+averaging, all the relevant dynamical scenarios are a function of the ratio
+between hard and easy axis anisotropies. We derive analytically the range of
+currents for which limit cycles exist and discuss the regimes in which the
+constant energy orbit averaging technique is applicable.",1305.5945v2
+2013-06-10,Imperfect Construction of Microclusters,"Microclusters are the basic building blocks used to construct cluster states
+capable of supporting fault-tolerant quantum computation. In this paper, we
+explore the consequences of errors on microcluster construction using two error
+models. To quantify the effect of the errors we calculate the fidelity of the
+constructed microclusters and the fidelity with which two such microclusters
+can be fused together. Such simulations are vital for gauging the capability of
+an experimental system to achieve fault tolerance.",1306.2202v1
+2013-06-19,Weyl Phases in Point-Group Symmetric Superconductors,"We study superconductivity in a Weyl semimetal with broken time-reversal
+symmetry and stabilized by a point-group symmetry. The resulting
+superconducting phase is characterized by topologically protected bulk nodes
+and surface states with Fermi arcs. The topological invariant governing the
+system is calculated using changes in eigenvalues of the point-group operator
+along high-symmetry momentum lines. We show that this invariant is determined
+by the Fermi surface topology of the Weyl semimetal. We discuss the effect of
+surface orientation and $C_4$-breaking strain as possible experimental
+consequences.",1306.4696v1
+2013-06-21,The Polarization Signature of Local Bulk Flows,"A large peculiar velocity of the intergalactic medium produces a Doppler
+shift of the cosmic microwave background with a frequency-dependent quadrupole
+term. This quadrupole will act as a source for polarization of the cosmic
+microwave background, creating a large-scale polarization anisotropy if the
+bulk flow is local and coherent on large scales. In the case where we are near
+the center of the moving region, the polarization signal is a pure quadrupole.
+We show that the signal is small, but detectable with future experiments for
+bulk flows as large as some recent reports.",1306.5248v3
+2013-07-21,Rigidity in the Positive Mass Theorem with Charge,"In this paper we show how a natural coupling of the Dirac equation with the
+generalized Jang equation, leads to a proof of the rigidity statement in the
+positive mass theorem with charge, without the maximal slicing condition,
+provided a solution to the coupled system exists.",1307.5499v4
+2014-01-08,Tri-Dirac Surface Modes in Topological Superconductors,"We propose a new type of topological surface modes having cubic dispersion in
+three-dimensional topological superconductors. Lower order dispersions are
+prohibited by the threefold rotational symmetry and time-reversal symmetry.
+Cooper pairing in the bulk changes sign under improper rotations, akin
+to$^{3}$He-B. The surface manifestations are a divergent surface density of
+states at the Fermi level and isospins that rotate three times as they circle
+the origin in momentum space. We propose that Heusler alloys with band
+inversion are candidate materials to harbor the novel topological
+superconductivity.",1401.1823v1
+2014-01-09,Automated Code Generation for Lattice Quantum Chromodynamics and beyond,"We present here our ongoing work on a Domain Specific Language which aims to
+simplify Monte-Carlo simulations and measurements in the domain of Lattice
+Quantum Chromodynamics. The tool-chain, called Qiral, is used to produce
+high-performance OpenMP C code from LaTeX sources. We discuss conceptual issues
+and details of implementation and optimization. The comparison of the
+performance of the generated code to the well-established simulation software
+is also made.",1401.2039v1
+2014-01-13,Effect of Dzyaloshinskii Moriya interaction on magnetic vortex,"The effect of the Dzyaloshinskii Moriya interaction on the vortex in magnetic
+microdisk was investigated by micro magnetic simulation based on the Landau
+Lifshitz Gilbert equation. Our results show that the DM interaction modifies
+the size of the vortex core, and also induces an out of plane magnetization
+component at the edge and inside the disk. The DM interaction can destabilizes
+one vortex handedness, generate a bias field to the vortex core and couple the
+vortex polarity and chirality. This DM-interaction-induced coupling can
+therefore provide a new way to control vortex polarity and chirality.",1401.3292v1
+2014-01-31,Self-Oscillation in Spin Torque Oscillator Stabilized by Field-like Torque,"The self-oscillation of the magnetization in a spin torque oscillator (STO)
+with a perpendicularly magnetized free layer and an in-plane magnetized pinned
+layer in the absence of an applied magnetic field was studied by numerically
+solving the Landau-Lifshitz-Gilbert equation. It was pointed out that
+field-like torque was necessary to realize stable self-oscillation in this type
+of STO at zero field. The numerical simulation at finite temperature showed
+that the presence of the field-like torque led to a high power with a
+relatively high oscillation frequency.",1401.8088v2
+2014-02-05,Spin-polarized transport in ferromagnetic multilayers: An unconditionally convergent FEM integrator,"We propose and analyze a decoupled time-marching scheme for the coupling of
+the Landau-Lifshitz-Gilbert equation with a quasilinear diffusion equation for
+the spin accumulation. This model describes the interplay of magnetization and
+electron spin accumulation in magnetic and non-magnetic multilayer structures.
+Despite the strong nonlinearity of the overall PDE system, the proposed
+integrator requires only the solution of two linear systems per time-step.
+Unconditional convergence of the integrator towards weak solutions is proved.",1402.0983v2
+2014-02-12,An efficient algorithm for the entropy rate of a hidden Markov model with unambiguous symbols,"We demonstrate an efficient formula to compute the entropy rate $H(\mu)$ of a
+hidden Markov process with $q$ output symbols where at least one symbol is
+unambiguously received. Using an approximation to $H(\mu)$ to the first $N$
+terms we give a $O(Nq^3$) algorithm to compute the entropy rate of the hidden
+Markov model. We use the algorithm to estimate the entropy rate when the
+parameters of the hidden Markov model are unknown.In the case of $q =2$ the
+process is the output of the Z-channel and we use this fact to give bounds on
+the capacity of the Gilbert channel.",1402.2733v2
+2014-03-24,Skyrmionic spin Seebeck effect via dissipative thermomagnonic torques,"We derive thermomagnonic torque and its ""$\beta$-type"" dissipative correction
+from the stochastic Landau-Lifshitz-Gilbert equation. The ""$\beta$-type""
+dissipative correction describes viscous coupling between magnetic dynamics and
+magnonic current and it stems from spin mistracking of the magnetic order. We
+show that thermomagnonic torque is important for describing temperature
+gradient induced motion of skyrmions in helical magnets while dissipative
+correction plays an essential role in generating transverse Magnus force. We
+propose to detect such skyrmionic motion by employing the transverse spin
+Seebeck effect geometry.",1403.6160v2
+2014-04-18,"Sparse Approximation, List Decoding, and Uncertainty Principles","We consider list versions of sparse approximation problems, where unlike the
+existing results in sparse approximation that consider situations with unique
+solutions, we are interested in multiple solutions. We introduce these problems
+and present the first combinatorial results on the output list size. These
+generalize and enhance some of the existing results on threshold phenomenon and
+uncertainty principles in sparse approximations. Our definitions and results
+are inspired by similar results in list decoding. We also present lower bound
+examples that bolster our results and show they are of the appropriate size.",1404.5190v2
+2014-04-25,Linewidth of Power Spectrum Originated from Thermal Noise in Spin Torque Oscillator,"A theoretical formula of the linewidth caused by the thermal activation in a
+spin torque oscillator with a perpendicularly magnetized free layer and an
+in-plane magnetized pinned layer was developed by solving the stochastic
+Landau-Lifshitz-Gilbert equation in the energy-phase representation. It is
+shown that the linewidth can be suppressed down to 0.1 MHz by applying a large
+current (10 mA for typical material parameters). A quality factor larger than
+10^{4} is predicted in the large current limit, which is two orders of
+magnitude larger than the recently observed experimental value.",1404.6558v1
+2014-09-04,Integer Generalized Splines on Cycles,"Let G be a graph whose edges are labeled by positive integers. Label each
+vertex with an integer and suppose if two vertices are joined by an edge, the
+vertex labels are congruent to each other modulo the edge label. The set of
+vertex labels satisfying this condition is called a generalized spline.
+Gilbert, Polster, and Tymoczko recently defined generalized splines based on
+work on polynomial splines by Billera, Rose, Haas, Goresky-Kottwitz-Machperson,
+and many others. We focus on generalized splines on $n$-cycles. We construct a
+particularly nice basis for the module of splines on $n$-cycles. As an
+application, we construct generalized splines on star graphs, wheel graphs, and
+complete graphs.",1409.1481v1
+2014-09-10,Proof of the Riemannian Penrose Inequality with Charge for Multiple Black Holes,"We present a proof of the Riemannian Penrose inequality with charge in the
+context of asymptotically flat initial data sets for the Einstein-Maxwell
+equations, having possibly multiple black holes with no charged matter outside
+the horizon, and satisfying the relevant dominant energy condition. The proof
+is based on a generalization of Hubert Bray's conformal flow of metrics adapted
+to this setting.",1409.3271v2
+2014-09-15,Enhanced synchronization in an array of spin torque nano oscillators in the presence of oscillating external magnetic field,"We demonstrate that the synchronization of an array of electrically coupled
+spin torque nano-oscillators (STNO) modelled by
+Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation can be enhanced appreciably
+in the presence of a common external microwave magnetic field. The applied
+microwave magnetic field stabilizes and enhances the regions of synchronization
+in the parameter space of our analysis, where the oscillators are exhibiting
+synchronized oscillations thereby emitting improved microwave power. To
+characterize the synchronized oscillations we have calculated the locking range
+in the domain of external source frequency.",1409.4384v2
+2014-10-19,Extensions of the Charged Riemannian Penrose Inequality,"In this paper we investigate the extension of the charged Riemannian Penrose
+inequality to the case where charges are present outside the horizon. We prove
+a positive result when the charge densities are compactly supported, and
+present a counterexample when the charges extend to infinity. We also discuss
+additional extensions to other matter models.",1410.5027v2
+2014-10-23,Quantum spin dynamics,"The classical Landau-Lifshitz equation has been derived from quantum
+mechanics. Starting point is the assumption of a non-Hermitian Hamilton
+operator to take the energy dissipation into account. The corresponding quantum
+mechanical time dependent Schr\""odinger, Liouville and Heisenberg equation have
+been described and the similarities and differences between classical and
+quantum mechanical spin dynamics have been discussed. Furthermore, a time
+dependent Schr\""odinger equation corresponding to the classical
+Landau-Lifshitz-Gilbert equation and two ways to include temperature into the
+quantum mechanical spin dynamics have been proposed.",1410.6383v1
+2014-12-04,Role of Magnetic Field in Self-Oscillation of Nanomagnet Excited by Spin Torque,"The critical current of the self-oscillation of spin torque oscillator (STO)
+consisting of a perpendicularly magnetized free layer and an in-plane
+magnetized pinned layer was studied by solving the Landau-Lifshitz-Gilbert
+(LLG) equation. We found that the critical current diverged at certain field
+directions, indicating that the self-oscillation does not occur at these
+directions. It was also found that the sign of the critical current changed
+depending on the applied field direction.",1412.1532v1
+2015-01-30,Memory functions of magnetic skyrmions,"Magnetic skyrmion, a swirling spin texture, in chiral magnets is
+characterized by (i) nano-scale size ($\sim$1nm -- 100nm), (ii) topological
+stability, and (iii) gyro-dynamics. These features are shown to be advantageous
+for (a) high-density data-storage, (b) nonvolatile memory, and (c) ultra-low
+current and energy cost manipulation, respectively. By the numerical
+simulations of Landau-Lifshitz-Gilbert equation, the elementary functions of
+skyrmions are demonstrated aiming at the design principles of skyrmionic memory
+devices.",1501.07650v1
+2015-02-14,Energy dissipation in single-domain ferromagnetic nanoparticles: Dynamical approach,"We study, both analytically and numerically, the phenomenon of energy
+dissipation in single-domain ferromagnetic nanoparticles driven by an
+alternating magnetic field. Our interest is focused on the power loss resulting
+from the Landau-Lifshitz-Gilbert equation, which describes the precessional
+motion of the nanoparticle magnetic moment. We determine the power loss as a
+function of the field amplitude and frequency and analyze its dependence on
+different regimes of forced precession induced by circularly and linearly
+polarized magnetic fields. The conditions to maximize the nanoparticle heating
+are also analyzed.",1502.04222v1
+2015-02-23,The Positive Mass Theorem for Multiple Rotating Charged Black Holes,"In this paper a lower bound for the ADM mass is given in terms of the angular
+momenta and charges of black holes present in axisymmetric initial data sets
+for the Einstein-Maxwell equations. This generalizes the mass-angular
+momentum-charge inequality obtained by Chrusciel and Costa to the case of
+multiple black holes. We also weaken the hypotheses used in the proof of this
+result for single black holes, and establish the associated rigidity statement.",1502.06290v2
+2015-02-24,An Upper Bound on the Minimum Distance of LDPC Codes over GF(q),"In [1] a syndrome counting based upper bound on the minimum distance of
+regular binary LDPC codes is given. In this paper we extend the bound to the
+case of irregular and generalized LDPC codes over GF(q). The comparison to the
+lower bound for LDPC codes over GF(q) and to the upper bound for non-binary
+codes is done. The new bound is shown to lie under the Gilbert-Varshamov bound
+at high rates.",1502.06874v1
+2015-03-16,Impact of Current on Static and Kinetic Depinning Fields of Domain Wall in Ferromagnetic Nanostrip,"The impact of current on static and kinetic depinning fields of a domain wall
+in an one dimensional ferromagnetic nanostrip is investigated by solving the
+Landau-Lifshitz-Gilbert equation with adiabatic and non-adiabatic spin-transfer
+torques analytically and numerically. The results show that in the absence of
+current, the static depinning field is greater than the kinetic depinning field
+and both the depinning fields decrease by the increase of current applied in a
+direction opposite to the direction of the applied field. Both the depinning
+fields can also be tuned by the current to make them equal.",1503.04553v1
+2015-04-17,Critical analysis and remedy of switching failures in straintronic logic using Bennett clocking in the presence of thermal fluctuations,"Straintronic logic is a promising platform for beyond Moore's law computing.
+Using Bennett clocking mechanism, information can propagate through an array of
+strain-mediated multiferroic nanomagnets exploiting the dipolar coupling
+between the magnets without having to physically interconnect them. Here we
+perform a critical analysis of switching failures, i.e., error in information
+propagation due to thermal fluctuations through a chain of such straintronic
+devices. We solved stochastic Landau-Lifshitz-Gilbert equation considering
+room-temperature thermal perturbations and show that magnetization switching
+may fail due to inherent magnetization dynamics accompanied by thermally
+broadened switching delay distribution. Avenues available to circumvent such
+issue are proposed.",1504.04618v1
+2015-06-18,Landauer limit of energy dissipation in a magnetostrictive particle,"According to Landauer's principle, a minimum amount of energy proportional to
+temperature must be dissipated during the erasure of a classical bit of
+information compensating the entropy loss, thereby linking the information and
+thermodynamics. Here we show that the Landauer limit of energy dissipation is
+achievable in a shape-anisotropic single-domain magnetostrictive nanomagnet
+having two mutually anti-parallel degenerate magnetization states that store a
+bit of information. We model the magnetization dynamics using stochastic
+Landau-Lifshitz-Gilbert equation in the presence of thermal fluctuations and
+show that on average the Landauer bound is satisfied, i.e., it accords to the
+generalized Landauer's principle for small systems with stochastic
+fluctuations.",1506.07897v1
+2015-06-29,Pseudo-Spin Based Dynamical Model for Polarisation Switching in Ferroelectrics,"A microscopic view of the response of the electric dipoles to a dynamic
+external field in a ferroelectric (FE) chain has been studied by two spin
+dynamics methods. One is the prominent micromagnetic approach, and the other is
+the micromagnetic approach with a variable size of the pseudo-spin. The energy
+stored in the ferroelectric chain is described by the transverse Ising model
+(TIM) with electric pseudo-spins. The simulations are based on a modified
+Landau-Lifshitz-Gilbert (LLG) equation which is precession free. The results
+obtained are shown and compared with the result supplemented by
+Landau-Devonshire (L-D) theory in the Appendix.",1506.08500v2
+2015-07-13,Explicit Construction of AG Codes from Generalized Hermitian Curves,"We present multi-point algebraic geometric codes overstepping the
+Gilbert-Varshamov bound. The construction is based on the generalized Hermitian
+curve introduced by A. Bassa, P. Beelen, A. Garcia, and H. Stichtenoth. These
+codes are described in detail by constrcting a generator matrix. It turns out
+that these codes have nice properties similar to those of Hermitian codes. It
+is shown that the duals are also such codes and an explicit formula is given.",1507.03418v1
+2015-07-22,Reflexive insensitive modal logics,"We analyze a class of modal logics rendered insensitive to reflexivity by way
+of a modification to the semantic definition of the modal operator. We explore
+the extent to which these logics can be characterized, and prove a general
+completeness theorem on the basis of a translation between normal modal logics
+and their reflexive-insensitive counterparts. Lastly, we provide a sufficient
+semantic condition describing when a similarly general soundness result is also
+available.",1507.06113v1
+2015-08-24,Spin Dynamics Simulation of the Magneto-Electric Effect in a Composite Multiferroic Chain,"A composite multiferroic chain with an interfacial linear magneto-electric
+coupling is used to study the magnetic and electric responses to an external
+magnetic or electric field. The simulation uses continuous spin dynamics
+through the Landau-Lifshitz-Gilbert equations of the magnetic spin and the
+electric pseudo-spin. The results demonstrate an accurate description of the
+distribution of the magnetisation and polarisation are induced by applied
+electric and magnetic field, respectively.",1508.05693v1
+2015-10-16,Reaction diffusion dynamics and the Schryer-Walker solution for domain walls of the Landau-Lifshitz-Gilbert equation,"We study the dynamics of the equation obtained by Schryer and Walker for the
+motion of domain walls. The reduced equation is a reaction diffusion equation
+for the angle between the applied field and the magnetization vector. If the
+hard axis anisotropy $K_d$ is much larger than the easy axis anisotropy $K_u$,
+there is a range of applied fields where the dynamics does not select the
+Schryer-Walker solution. We give analytic expressions for the speed of the
+domain wall in this regime and the conditions for its existence.",1510.04927v1
+2015-11-06,Dynamic Response in a Finite Size Composite Multiferroic Thin Film,"Composite multiferroics, heterostructures of ferromagnetic (FM) and
+ferroelectric (FE) materials, are characterized by a remarkable magnetoelectric
+effect at the interface. Previous work has supported the ferromagnetic
+structure with magnetic spins and the ferroelectric with pseudospins which act
+as electric dipoles in a microscopic model, coupled with a magnetoelectric
+interaction [J. Appl. Phys. 118, 124109 (2015)]. In this work, by solving the
+stochastic Landau-Lifshitz-Gilbert equation, the electric-field-induced
+magnetization switching in a twisted boundary condition has been studied, and a
+behavior of domain wall in the ferromagnetic structure is discussed.",1511.01982v2
+2015-12-18,Existence of travelling-wave solutions representing domain wall motion in a thin ferromagnetic nanowire,"We study the dynamics of a domain wall under the influence of applied
+magnetic fields in a one-dimensional ferromagnetic nanowire, governed by the
+Landau--Lifshitz--Gilbert equation. Existence of travelling-wave solutions
+close to two known static solutions is proven using
+implicit-function-theorem-type arguments.",1512.06016v2
+2016-01-18,On Simultaneous Percolation with Two Disk Types,"In this paper we consider the simultaneous percolation of two Gilbert disk
+models. The two models are connected through excluding disks, which prevent
+elements of the second model to be in the vicinity of the first model. Under
+these assumptions we characterize the region of densities in which the two
+models both have a unique infinite connected component. The motivation for this
+work is the co-existence of two cognitive radio networks.",1601.04471v2
+2016-01-22,Toward a New Microscopic Framework for Kondo Lattice Materials,"Understanding the emergence and subsequent behavior of heavy electrons in
+Kondo lattice materials is one of the grand challenges in condensed matter
+physics. In this perspective we review the progress that has been made during
+the past decade and suggest some directions for future research. Our focus will
+be on developing a new microscopic framework that incorporates the basic
+concepts that emerge from a phenomenological description of the key
+experimental findings.",1601.06050v1
+2016-02-01,The Eddy Current-LLG Equations-Part I: FEM-BEM Coupling,"We analyse a numerical method for the coupled system of the eddy current
+equations in $\mathbb{R}^3$ with the Landau-Lifshitz-Gilbert equation in a
+bounded domain. The unbounded domain is discretised by means of
+finite-element/boundary-element coupling. Even though the considered problem is
+strongly nonlinear, the numerical approach is constructed such that only two
+linear systems per time step have to be solved. In this first part of the
+paper, we prove unconditional weak convergence (of a subsequence) of the
+finite-element solutions towards a weak solution. A priori error estimates will
+be presented in the second part.",1602.00744v1
+2016-02-01,The Eddy Current--LLG Equations: FEM-BEM Coupling and A Priori Error Estimates,"We analyze a numerical method for the coupled system of the eddy current
+equations in $\mathbb{R}^3$ with the Landau-Lifshitz-Gilbert equation in a
+bounded domain. The unbounded domain is discretized by means of
+finite-element/boundary-element coupling. Even though the considered problem is
+strongly nonlinear, the numerical approach is constructed such that only two
+linear systems per time step have to be solved. We prove unconditional weak
+convergence (of a subsequence) of the finite-element solutions towards a weak
+solution. We establish a priori error estimates if a sufficiently smooth strong
+solution exists. Numerical experiments underlining the theoretical results are
+presented.",1602.00745v2
+2016-02-24,Partial Category Actions on Sets and Topological Spaces,"We introduce (continuous) partial category actions on sets (topological
+spaces) and show that each such action admits a universal globalization.
+Thereby, we obtain a simultaneous generalization of corresponding results for
+groups, by Kellendonk and Lawson, and for monoids, by Megrelishvili and
+Schroder. We apply this result to the special case of partial groupoid actions
+where we obtain a sharpening of a result by Gilbert, concerning ordered
+groupoids, in the sense that mediating functions between universal
+globalizations always are injective.",1602.07541v4
+2016-05-20,Interlayer interaction in multilayer CoPt/Co structures,"We report a study of interlayer exchange interaction in multilayer CoPt/Co
+structures consisting of periodic CoPt multilayer film with an ""easy axis""
+anisotropy and thick Co layer with an ""easy plane"" anisotropy separated by Pt
+spacer with variable thickness. The magnetooptical Kerr effect (MOKE) and
+ferromagnetic resonance (FMR) measurements show up the essentially
+non-collinear state of magnetic moments of the layers and strong exchange
+coupling between CoPt and Co subsystems. The estimation of effective anisotropy
+and exchange coupling in a simple model based on the Landau-Lifshitz-Gilbert
+equation describing magnetization dynamics was performed.",1605.06468v1
+2016-06-02,On self-dual double negacirculant codes,"Double negacirculant (DN) codes are the analogues in odd characteristic of
+double circulant codes. Self-dual DN codes of odd dimension are shown to be
+consta-dihedral. Exact counting formulae are derived for DN codes. The special
+class of length a power of two is studied by means of Dickson polynomials, and
+is shown to contain families of codes with relative distances satisfying a
+modified Gilbert-Varshamov bound.",1606.00815v1
+2016-07-12,Tailoring the topological details of the magnetic skyrmion by the spin configuration at the edges,"The magnetic skyrmion structure can be formed in the chiral magnets (CMs)
+with strong Dzyaloshinskii-Moriya interactions. In this work, we propose a way
+of artificially tailoring the topological details of the skyrmion such as its
+radial and whirling symmetric patterns by external magnetic fields besieging
+the CM slab. As long as the boundary magnetic fields are strong enough to fix
+the boundary ferromagnetism, the attained skyrmion profile is stable over time.
+The dynamics of spins is considered by numerically solving the non-equilibrium
+Landau-Lifshitz-Gilbert equation.",1607.03268v2
+2016-09-07,Entanglement manipulation by a magnetic pulse in Gd3N@C80 endohedral metallofullerenes on a Cu(001) surface,"In this paper we present result of theoretical calculation of entanglement
+within a spin structure of Gd3N@C80 under the in uence of rectangular impulses.
+Research is conducted using general spin Hamiltonian within SSNQ (spin system
+of N-qubits). Calculation of entanglement with variable impulse is performed
+using the time-dependent Landau-Lifshitz-Gilbert equation with spin-spin
+correlation function. We show that long rectangular impulse (t=850ps) can be
+used for maintaining of entanglement value. This allows us to offer a new
+algorithm which can be used to reduce the challenge of decoherence to logical
+scheme optimization.",1609.01959v1
+2016-09-10,Optical tomography on graphs,"We present an algorithm for solving inverse problems on graphs analogous to
+those arising in diffuse optical tomography for continuous media. In
+particular, we formulate and analyze a discrete version of the inverse Born
+series, proving estimates characterizing the domain of convergence,
+approximation errors, and stability of our approach. We also present a
+modification which allows additional information on the structure of the
+potential to be incorporated, facilitating recovery for a broader class of
+problems.",1609.03041v1
+2016-09-30,Interaction Between a Domain Wall and Spin Supercurrent in Easy-cone Magnets,"A domain wall and spin supercurrent can coexist in magnets with easy-cone
+anisotropy owing to simultaneous spontaneous breaking of Z$_2$ and U(1)
+symmetries. Their interaction is theoretically investigated in quasi
+one-dimensional ferromagnets within the Landau-Lifshitz-Gilbert phenomenology.
+Specifically, we show that spin supercurrent can exert the torque on a domain
+wall and thereby drive it. We also show, as a reciprocal phenomenon, a
+field-induced motion of a domain wall can generate spin supercurrent.",1610.00034v1
+2016-10-04,A Local Inverse Formula and a Factorization,"When a matrix has a banded inverse there is a remarkable formula that quickly
+computes that inverse, using only local information in the original matrix.
+This local inverse formula holds more generally, for matrices with sparsity
+patterns that are examples of chordal graphs or perfect eliminators. The
+formula has a long history going back at least as far as the completion problem
+for covariance matrices with missing data. Maximum entropy estimates,
+log-determinants, rank conditions, the Nullity Theorem and wavelets are all
+closely related, and the formula has found wide applications in machine
+learning and graphical models. We describe that local inverse and explain how
+it can be understood as a matrix factorization.",1610.01230v1
+2016-10-10,Parametric frequency mixing in the magneto-elastically driven FMR-oscillator,"We demonstrate the nonlinear frequency conversion of ferromagnetic resonance
+(FMR) frequency by optically excited elastic waves in a thin metallic film on
+dielectric substrates. Time-resolved probing of the magnetization directly
+witnesses magneto-elastically driven second harmonic generation, sum- and
+difference frequency mixing from two distinct frequencies, as well as
+parametric downconversion of each individual drive frequency. Starting from the
+Landau-Lifshitz-Gilbert equations, we derive an analytical equation of an
+elastically driven nonlinear parametric oscillator and show that frequency
+mixing is dominated by the parametric modulation of FMR frequency.",1610.02926v1
+2016-11-05,Magnonic analog of relativistic Zitterbewegung in an antiferromagnetic spin chain,"We theoretically investigate the spin wave (magnon) excitations in a
+classical antiferromagnetic spin chain with easy-axis anisotropy. We obtain a
+Dirac-like equation by linearizing the Landau- Lifshitz-Gilbert equation in
+this antiferromagnetic system, in contrast to the ferromagnetic system in which
+a Schr\""{o}dinger equation is derived. The Hamiltonian operator in the
+Dirac-like equation is a pseudo-Hermitian. We compute and demonstrate the
+relativistic Zitterbewegung (trembling motion) in the antiferromagnetic spin
+chain by measuring the expectation values of the wave packet position.",1611.01512v2
+2016-11-15,The norm of the Fourier transform on compact or discrete abelian groups,"We calculate the norm of the Fourier operator from $L^p(X)$ to $L^q(\hat{X})$
+when $X$ is an infinite locally compact abelian group that is, furthermore,
+compact or discrete. This subsumes the sharp Hausdorff-Young inequality on such
+groups. In particular, we identify the region in $(p,q)$-space where the norm
+is infinite, generalizing a result of Fournier, and setting up a contrast with
+the case of finite abelian groups, where the norm was determined by Gilbert and
+Rzeszotnik. As an application, uncertainty principles on such groups expressed
+in terms of R\'enyi entropies are discussed.",1611.04692v1
+2016-12-01,Optimizing Quantiles in Preference-based Markov Decision Processes,"In the Markov decision process model, policies are usually evaluated by
+expected cumulative rewards. As this decision criterion is not always suitable,
+we propose in this paper an algorithm for computing a policy optimal for the
+quantile criterion. Both finite and infinite horizons are considered. Finally
+we experimentally evaluate our approach on random MDPs and on a data center
+control problem.",1612.00094v1
+2017-02-02,Magnon Condensation and Spin Superfluidity,"We consider the phenomenon of Bose-Einstein condensation of quasi-equilibrium
+magnons which leads to a spin superfluidity, the coherent quantum transfer of
+magnetization in magnetic materials. These phenomena are beyond the classical
+Landau-Lifshitz-Gilbert paradigm. The critical conditions for excited magnon
+density for ferro- and antiferromagnets, bulk and thin films are estimated and
+discussed. The BEC should occur in the antiferromagnetic hematite at much lower
+excited magnon density compared to the ferromagnetic YIG.",1702.00846v2
+2017-02-09,Transient spin dynamics in a single-molecule magnet,"We explore the limitations and validity of semi-classically formulated spin
+equations of motion. Using a single-molecule magnet as a test model, we employ
+three qualitatively different approximation schemes. From a microscopic model,
+we derive a generalized spin equation of motion in which the parameters have a
+non-local time-dependence. This dynamical equation is simplified to the
+Landau-Lifshitz-Gilbert equation with i) time-dependent, and ii)
+time-independent parameters. We show that transient dynamics is essentially
+non-existing in the latter approximation, while the former breaks down in the
+regime of strong coupling between the spin and the itinerant electrons.",1702.02820v2
+2017-03-05,On the VC-Dimension of Binary Codes,"We investigate the asymptotic rates of length-$n$ binary codes with
+VC-dimension at most $dn$ and minimum distance at least $\delta n$. Two upper
+bounds are obtained, one as a simple corollary of a result by Haussler and the
+other via a shortening approach combining Sauer-Shelah lemma and the linear
+programming bound. Two lower bounds are given using Gilbert-Varshamov type
+arguments over constant-weight and Markov-type sets.",1703.01586v2
+2017-03-09,Long quasi-polycyclic $t-$CIS codes,"We study complementary information set codes of length $tn$ and dimension $n$
+of order $t$ called ($t-$CIS code for short). Quasi-cyclic and quasi-twisted
+$t$-CIS codes are enumerated by using their concatenated structure. Asymptotic
+existence results are derived for one-generator and have co-index $n$ by
+Artin's conjecture for quasi cyclic and special case for quasi twisted. This
+shows that there are infinite families of long QC and QT $t$-CIS codes with
+relative distance satisfying a modified Varshamov-Gilbert bound for rate $1/t$
+codes.
+  Similar results are defined for the new and more general class of
+quasi-polycyclic codes introduced recently by Berger and Amrani.",1703.03109v1
+2017-09-05,On the Lagrangian branched transport model and the equivalence with its Eulerian formulation,"First we present two classical models of Branched Transport: the Lagrangian
+model introduced by Bernot, Caselles, Morel, Maddalena, Solimini, and the
+Eulerian model introduced by Xia. An emphasis is put on the Lagrangian model,
+for which we give a complete proof of existence of minimizers in a
+--hopefully-- simplified manner. We also treat in detail some
+$\sigma$-finiteness and rectifiability issues to yield rigorously the energy
+formula connecting the irrigation cost I$\alpha$ to the Gilbert Energy
+E$\alpha$. Our main purpose is to use this energy formula and exploit a Smirnov
+decomposition of vector flows, which was proved via the Dacorogna-Moser
+approach by Santambrogio, to establish the equivalence between the Lagrangian
+and Eulerian models.",1709.01414v1
+2017-09-09,On Low-Risk Heavy Hitters and Sparse Recovery Schemes,"We study the heavy hitters and related sparse recovery problems in the
+low-failure probability regime. This regime is not well-understood, and has
+only been studied for non-adaptive schemes. The main previous work is one on
+sparse recovery by Gilbert et al.(ICALP'13). We recognize an error in their
+analysis, improve their results, and contribute new non-adaptive and adaptive
+sparse recovery algorithms, as well as provide upper and lower bounds for the
+heavy hitters problem with low failure probability.",1709.02919v3
+2017-10-30,Lattice calculation of hadronic tensor of the nucleon,"We report an attempt to calculate the deep inelastic scattering structure
+functions from the hadronic tensor calculated on the lattice. We used the
+Backus-Gilbert reconstruction method to address the inverse Laplace
+transformation for the analytic continuation from the Euclidean to the
+Minkowski space.",1710.11145v1
+2017-10-31,TF Boosted Trees: A scalable TensorFlow based framework for gradient boosting,"TF Boosted Trees (TFBT) is a new open-sourced frame-work for the distributed
+training of gradient boosted trees. It is based on TensorFlow, and its
+distinguishing features include a novel architecture, automatic loss
+differentiation, layer-by-layer boosting that results in smaller ensembles and
+faster prediction, principled multi-class handling, and a number of
+regularization techniques to prevent overfitting.",1710.11555v1
+2017-11-08,Micromagnetic simulation study of a disordered model for one-dimensional granular perovskite manganite oxide nanostructures,"Chemical techniques are an efficient method to synthesize one-dimensional
+perovskite manganite oxide nanostructures with a granular morphology, that is,
+formed by arrays of monodomain magnetic nanoparticles. Integrating the
+stochastic Landau-Lifshitz-Gilbert equation, we simulate the dynamics of a
+simple disordered model for such materials that only takes into account the
+morphological characteristics of their nanograins. We show that it is possible
+to describe reasonably well experimental hysteresis loops reported in the
+literature for single La_0.67Ca_0.33MnO_3 nanotubes and powders of these
+nanostructures, simulating small systems consisting of only 100 nanoparticles.",1711.03159v2
+2017-11-21,Construction of asymptotically good locally repairable codes via automorphism groups of function fields,"Locally repairable codes have been investigated extensively in recent years
+due to practical application in distributed storage as well as theoretical
+interest. However, not much work on asymptotical behavior of locally repairable
+codes has been done until now. In particular, there is a little result on
+constructive lower bound on asymptotical behavior of locally repairable codes.
+In this paper, we extend the construction given in \cite{BTV17} via
+automorphism groups of function field towers. The main advantage of our
+construction is to allow more flexibility of locality. Furthermore, we show
+that the Gilbert-Varshamov type bound on locally repairable codes can be
+improved for all sufficiently large alphabet size $q$.",1711.07703v1
+2017-11-21,Stability of axisymmetric chiral skyrmions,"We examine topological solitons in a minimal variational model for a chiral
+magnet, so-called chiral skyrmions. In the regime of large background fields,
+we prove linear stability of axisymmetric chiral skyrmions under arbitrary
+perturbations in the energy space, a long-standing open question in physics
+literature. Moreover, we show strict local minimality of axisymmetric chiral
+skyrmions and nearby existence of moving soliton solution for the
+Landau-Lifshitz-Gilbert equation driven by a small spin transfer torque.",1711.07717v1
+2017-12-13,Mutual synchronization of spin-torque oscillators consisting of perpendicularly magnetized free layers and in-plane magnetized pinned layers,"A mutual synchronization of spin-torque oscillators coupled through current
+injection is studied theoretically. Models of electrical coupling in parallel
+and series circuits are proposed. Solving the Landau-Lifshitz-Gilbert equation,
+excitation of in-phase or antiphase synchronization, depending on the ways the
+oscillators are connected, is found. It is also found from both analytical and
+numerical calculations that the current-frequency relations for both parallel
+and series circuits are the same as that for a single spin-torque oscillator.",1712.04591v1
+2018-01-25,Pharmacokinetics Simulations for Studying Correlates of Prevention Efficacy of Passive HIV-1 Antibody Prophylaxis in the Antibody Mediated Prevention (AMP) Study,"A key objective in two phase 2b AMP clinical trials of VRC01 is to evaluate
+whether drug concentration over time, as estimated by non-linear mixed effects
+pharmacokinetics (PK) models, is associated with HIV infection rate. We
+conducted a simulation study of marker sampling designs, and evaluated the
+effect of study adherence and sub-cohort sample size on PK model estimates in
+multiple-dose studies. With m=120, even under low adherence (about half of
+study visits missing per participant), reasonably unbiased and consistent
+estimates of most fixed and random effect terms were obtained. Coarsened marker
+sampling schedules were also studied.",1801.08626v1
+2018-03-30,Nanostructured Ceramic Oxides with a Slow Crack Growth Resistance Close to Covalent Materials,"Oxide ceramics are sensitive to slow crack growth because adsorption of water
+can take place at the crack tip, leading to a strong decrease of the surface
+energy in humid (or air) conditions. This is a major drawback concerning
+demanding, long-term applications such as orthopaedic implants. Here we show
+that a specific nanostructuration of ceramic oxides can lead to a crack
+resistance never reached before, similar to that of covalent ceramics.",1804.01393v1
+2018-05-30,Quantum Annealed Criticality,"Experimentally there exist many materials with first-order phase transitions
+at finite temperature that display quantum criticality. Classically a
+strain-energy density coupling is known to drive first-order transitions in
+compressible systems, and here we generalize this Larkin-Pikin mechanism to the
+quantum case. We show that if the T=0 system lies above its upper critical
+dimension, the line of first-order transitions can end in a quantum annealed
+critical point where zero-point fluctuations restore the underlying criticality
+of the order parameter.",1805.11771v1
+2018-08-03,A thermally driven spin-transfer-torque system far from equilibrium: enhancement of the thermoelectric current via pumping current,"We consider a small itinerant ferromagnet exposed to an external magnetic
+field and strongly driven by a thermally induced spin current. For this model,
+we derive the quasi-classical equations of motion for the magnetization where
+the effects of a dynamical non-equilibrium distribution function are taken into
+account self-consistently. We obtain the Landau-Lifshitz-Gilbert equation
+supplemented by a spin-transfer torque term of Slonczewski form. We identify a
+regime of persistent precessions in which we find an enhancement of the
+thermoelectric current by the pumping current.",1808.01192v1
+2018-09-12,But How Does It Work in Theory? Linear SVM with Random Features,"We prove that, under low noise assumptions, the support vector machine with
+$N\ll m$ random features (RFSVM) can achieve the learning rate faster than
+$O(1/\sqrt{m})$ on a training set with $m$ samples when an optimized feature
+map is used. Our work extends the previous fast rate analysis of random
+features method from least square loss to 0-1 loss. We also show that the
+reweighted feature selection method, which approximates the optimized feature
+map, helps improve the performance of RFSVM in experiments on a synthetic data
+set.",1809.04481v3
+2018-09-22,"Optimizing a Generalized Gini Index in Stable Marriage Problems: NP-Hardness, Approximation and a Polynomial Time Special Case","This paper deals with fairness in stable marriage problems. The idea studied
+here is to achieve fairness thanks to a Generalized Gini Index (GGI), a
+well-known criterion in inequality measurement, that includes both the
+egalitarian and utilitarian criteria as special cases. We show that determining
+a stable marriage optimizing a GGI criterion of agents' disutilities is an
+NP-hard problem. We then provide a polynomial time 2-approximation algorithm in
+the general case, as well as an exact algorithm which is polynomial time in the
+case of a constant number of non-zero weights parametrizing the GGI criterion.",1809.08453v1
+2018-10-17,Out-of-plane auto-oscillation in spin Hall oscillator with additional polarizer,"The theoretical investigation on magnetization dynamics excited by the spin
+Hall effect in metallic multilayers having two ferromagnets is discussed. The
+relaxation of the transverse spin in one ferromagnet enables us to manipulate
+the direction of the spin-transfer torque excited in another ferromagnet,
+although the spin-polarization originally generated by the spin Hall effect is
+geometrically fixed. Solving the Landau-Lifshitz-Gilbert-Slonczewski equation,
+the possibility to excite an out-of-plane auto-oscillation of an in-plane
+magnetized ferromagnet is presented. An application to magnetic recording using
+microwave-assisted magnetization reversal is also discussed.",1810.07831v1
+2018-11-23,Most Graphs are Knotted,"We present four models for a random graph and show that, in each case, the
+probability that a graph is intrinsically knotted goes to one as the number of
+vertices increases. We also argue that, for $k \geq 18$, most graphs of order
+$k$ are intrinsically knotted and, for $k \geq 2n+9$, most of order $k$ are not
+$n$-apex. We observe that $p(n) = 1/n$ is the threshold for intrinsic knotting
+and linking in Gilbert's model.",1811.09726v1
+2018-12-13,Entanglement-assisted quantum error-correcting codes over arbitrary finite fields,"We prove that the known formulae for computing the optimal number of
+maximally entangled pairs required for entanglement-assisted quantum
+error-correcting codes (EAQECCs) over the binary field hold for codes over
+arbitrary finite fields as well. We also give a Gilbert-Varshamov bound for
+EAQECCs and constructions of EAQECCs coming from punctured self-orthogonal
+linear codes which are valid for any finite field.",1812.05312v4
+2019-01-23,Coupled dynamics of magnetizations in spin-Hall oscillators via spin current injection,"An array of spin torque oscillators (STOs) for practical applications such as
+pattern recognition was recently proposed, where several STOs are connected by
+a common nonmagnet. In this structure, in addition to the electric and/or
+magnetic interactions proposed in previous works, the STOs are spontaneously
+coupled to each other through the nonmagnetic connector, due to the injection
+of spin current. Solving the Landau-Lifshitz-Gilbert equation numerically for
+such system consisting of three STOs driven by the spin Hall effect, it is
+found that both in-phase and antiphase synchronization of the STOs can be
+achieved by adjusting the current density and appropriate distance between the
+oscillators.",1901.07669v1
+2019-01-28,A Multi-parameter regression model for interval censored survival data,"We develop flexible multi-parameter regression survival models for interval
+censored survival data arising in longitudinal prospective studies and
+longitudinal randomised controlled clinical trials. A multi-parameter Weibull
+regression survival model, which is wholly parametric, and has non-proportional
+hazards, is the main focus of the paper. We describe the basic model, develop
+the interval-censored likelihood and extend the model to include gamma frailty
+and a dispersion model. We evaluate the models by means of a simulation study
+and a detailed re-analysis of data from the Signal Tandmobiel$^{\circledR}$
+study. The results demonstrate that the multi-parameter regression model with
+frailty is computationally efficient and provides an excellent fit to the data.",1901.09634v1
+2019-02-15,Stochastic homogenization of the Landau-Lifshitz-Gilbert equation,"Following the ideas of V. V. Zhikov and A. L. Pyatnitski, and more precisely
+the stochastic two-scale convergence, this paper establishes a homogenization
+theorem in a stochastic setting for two nonlinear equations : the equation of
+harmonic maps into the sphere and the Landau-Lifschitz equation. These
+equations have strong nonlinear features, in particular, in general their
+solutions are not unique.",1902.05743v1
+2019-03-06,Cluster multipole dynamics in non-collinear antiferromagnets,"A systematic framework to investigate spin dynamics in non-collinear
+antiferromagnet is proposed. Taking Mn$_3$Sn as a representative example, we
+derive an effective low energy model based on the multipole expansion of the
+magnetic structure, and investigate the uniform precession and the domain wall
+dynamics. We show that the solution for the effective model accurately
+reproduces the numerical calculation of the Landau-Lifshitz-Gilbert equations.
+Our results indicate that Mn$_3$Sn has preferable properties for applications
+to a racetrack memory and a spin torque oscillator, and thus, is a promising
+candidate for new devices by using the multipole degrees of freedom.",1903.02259v1
+2019-03-22,Learning magnetization dynamics,"Deep neural networks are used to model the magnetization dynamics in magnetic
+thin film elements. The magnetic states of a thin film element can be
+represented in a low dimensional space. With convolutional autoencoders a
+compression ratio of 1024:1 was achieved. Time integration can be performed in
+the latent space with a second network which was trained by solutions of the
+Landau-Lifshitz-Gilbert equation. Thus the magnetic response to an external
+field can be computed quickly.",1903.09499v1
+2019-04-01,Synchrony breakdown and noise-induced oscillation death in ensembles of serially connected spin-torque oscillators,"We consider collective dynamics in the ensemble of serially connected
+spin-torque oscillators governed by the Landau-Lifshitz-Gilbert-Slonczewski
+magnetization equation. Proximity to homoclinicity hampers synchronization of
+spin-torque oscillators: when the synchronous ensemble experiences the
+homoclinic bifurcation, the Floquet multiplier, responsible for the temporal
+evolution of small deviations from the ensemble mean, diverges. Depending on
+the configuration of the contour, sufficiently strong common noise, exemplified
+by stochastic oscillations of the current through the circuit, may suppress
+precession of the magnetic field for all oscillators. We derive the explicit
+expression for the threshold amplitude of noise, enabling this suppression.",1904.00897v1
+2019-04-21,Global classical solutions to an evolutionary model for magnetoelasticity,"In this paper, we first prove the local-in-time existence of the evolutionary
+model for magnetoelasticity with finite initial energy by employing the
+nonlinear iterative approach given in \cite{Jiang-Luo-2019-SIAM} to deal with
+the geometric constraint $M \in \mathbb{S}^{d-1}$ in the
+Landau-Lifshitz-Gilbert (LLG) equation. Inspired by
+\cite{Lin-Liu-Zhang-CPAM2005, Lin-Zhang-2008-CPAM}, we reformulate the
+evolutionary model for magnetoelasticity with vanishing external magnetic field
+$H_{ext}$, so that a further dissipative term will be sought from the elastic
+stress. We thereby justify the global well-posedness to the evolutionary model
+for magnetoelasticity with zero external magnetic field under small size of
+initial data.",1904.09531v1
+2019-06-21,Thermal Collapse of a Skyrmion,"Thermal collapse of an isolated skyrmion on a two-dimensional spin lattice
+has been investigated. The method is based upon solution of the system of
+stochastic Landau-Lifshitz-Gilbert equations for up $10^4$ spins. Recently
+developed pulse-noise algorithm has been used for the stochastic component of
+the equations. The collapse rate follows the Arrhenius law. Analytical formulas
+derived within a continuous spin-field model support numerically-obtained
+values of the energy barrier and the pre-exponential factor, and their
+dependence on the magnetic field. Our findings agree with experiments, as well
+as with recent numerical results obtained by other methods.",1906.09132v3
+2019-06-23,"Random subgroups, automorphisms, splittings","We show that, if $H$ is a random subgroup of a finitely generated free group
+$F_k$, only inner automorphisms of $F_k$ may leave $H$ invariant. A similar
+result holds for random subgroups of toral relatively hyperbolic groups, more
+generally of groups which are hyperbolic relative to slender subgroups. These
+results follow from non-existence of splittings over slender groups which are
+relative to a random group element. Random subgroups are defined using random
+walks or balls in a Cayley tree of $F_k$.",1906.09654v1
+2019-07-28,Polarization of the Cosmic Infrared Background Fluctuations,"The cosmic infrared background (CIB) is slightly polarized. Polarization
+directions of individual galaxies could be aligned with tidal fields around
+galaxies, resulting in nonzero CIB polarization. We use a linear intrinsic
+alignment model to theoretically predict angular correlations of the CIB
+polarization fluctuations and find that electriclike and curl-like ($B$-mode)
+polarization modes are equally generated with power four orders of magnitude
+less than its intensity. The CIB $B$-mode signal is negligible and not a
+concerning foreground for the inflationary $B$-mode searches at nominal
+frequencies for cosmic microwave background measurements, but could be detected
+at submillimetre wavelengths by future space missions.",1907.12085v1
+2019-08-05,Constructive asymptotic bounds of locally repairable codes via function fields,"Locally repairable codes have been investigated extensively in recent years
+due to practical applications in distributed and cloud storage systems.
+However, there are few asymptotical constructions of locally repairable codes
+in the literature. In this paper, we provide an explicit asymptotic
+construction of locally repairable codes over arbitrary finite fields from
+local expansions of functions at a rational place. This construction gives a
+Tsfasman-Vladut-Zink type bound for locally repairable codes. Its main
+advantage is that there are no constraints on both locality and alphabet size.
+Furthermore, we show that the Gilbert-Varshamov type bound on locally
+repairable codes over non-prime finite fields can be exceeded for sufficiently
+large alphabet size.",1908.01471v1
+2019-10-25,Application-Layer Coding with Intermittent Feedback under Delay and Duty-Cycle Constraints,"We propose two application-layer coding schemes for delay-constrained
+point-to-point packet communications with restrictions on the transmitter's
+maximum duty-cycle. The schemes operate over GF(2) and utilize intermittently
+available receiver feedback for erasure correction. Applications that will
+benefit from the proposed schemes include wireless sensor networks in which
+energy-constrained sensors must deliver readings to a gateway within a
+deadline. Simulation results for independent Bernoulli erasure channels,
+Gilbert-Elliott channels, and Long Range (LoRa) communications demonstrate
+orders-of-magnitude reductions in the delivery failure rate as compared to
+feedback-assisted repetition redundancy and a blind coding scheme that does not
+utilize feedback.",1910.11700v2
+2019-10-28,Dissipative solutions to a system for the flow of magnetoviscoelastic materials,"We address the question of global in time existence of solutions to a
+magnetoviscoelastic system with general initial data. We show that the notion
+of dissipative solutions allows to prove such an existence in two and three
+dimensions. This extends an earlier result for the viscoelastic subsystem to
+the setting which includes the magnetization vector and its evolution in terms
+of a Landau-Lifshitz-Gilbert equation.",1910.12751v2
+2019-12-09,Multi-reference protocol for (auto)ionization spectra: application to molecules,"We present the application of the spherically averaged continuum model to the
+evaluation of molecular photoelectron and resonant Auger electron spectra. In
+this model, the continuum wave function is obtained in a numerically efficient
+way by solving the radial Schr\""odinger equation with a spherically averaged
+molecular potential. Different approximations to the Auger transition matrix
+element and, in particular, the one-center approximation are thoroughly tested
+against experimental data for the CH$_4$, O$_2$, NO$_2$, and pyrimidine
+molecules. In general, this approach appears to estimate the shape of the
+photoelectron and autoionization spectra as well as the total Auger decay rates
+with reasonable accuracy, allowing for the interpretation of experimental
+results.",1912.04139v1
+2020-01-25,Phase estimation of spin-torque oscillator by nonlinear spin-torque diode effect,"A theoretical analysis is developed on spin-torque diode effect in nonlinear
+region. An analytical solution of the diode voltage generated from spin-torque
+oscillator by the rectification of an alternating current is derived. The diode
+voltage is revealed to depend nonlinearly on the phase difference between the
+oscillator and the alternating current. The validity of the analytical
+prediction is confirmed by numerical simulation of the Landau-Lifshitz-Gilbert
+equation. The results indicate that the spin-torque diode effect is useful to
+evaluate the phase of a spin-torque oscillator in forced synchronization state.",2001.09247v1
+2020-04-06,Frequency enhancement and power tunability in tilted polarizer spin-torque nano oscillator,"In the absence of an applied magnetic field, a spin-torque nano
+oscillator(STNO) with a tilted polarizer is studied using numerical simulation
+of the associated Landau-Lifshitz-Gilbert-Slonczewski equation. We find
+considerable enhancement of frequency by tilting the polarizer out-of-plane
+appropriately. Also, we observe improved tunability of frequency of
+oscillations from 15 GHz to 75 GHz and increment in the power spectral density
+by current and tilt angle. In addition, our findings and insights pave a simple
+way for nanoscale level microwave generators to be implemented.",2004.02659v1
+2020-05-11,Perspective on Metallic Antiferromagnets,"Antiferromagnet materials have recently gained renewed interest due to their
+possible use in spintronics technologies, where spin transport is the
+foundation of their functionalities. In that respect metallic antiferromagnets
+are of particular interest, since they enable complex interplays between
+electronic charge transport, spin, optical, and magnetization dynamics. Here we
+review phenomena where the metallic conductivity provides unique perspectives
+for the practical use and fundamental properties of antiferromagnetic
+materials.",2005.05247v1
+2020-07-09,Enumerating alternating matrix spaces over finite fields with explicit coordinates,"We initiate the study of enumerating linear subspaces of alternating matrices
+over finite fields with explicit coordinates. We postulate that this study can
+be viewed as a linear algebraic analogue of the classical topic of enumerating
+labelled graphs. To support this viewpoint, we present q-analogues of Gilbert's
+formula for enumerating connected graphs (Can. J. Math., 1956), and Read's
+formula for enumerating c-colored graphs (Can. J. Math., 1960). We also develop
+an analogue of Riddell's formula relating the exponential generating function
+of graphs with that of connected graphs (Riddell's PhD thesis, 1951), building
+on Eulerian generating functions developed by Srinivasan (Discrete Math.,
+2006).",2007.05108v1
+2020-08-06,"On Passivity, Feedback Passivity, And Feedback Passivity Over Erasure Network: A Piecewise Affine Approximation Approach","In this paper, we deal with the problem of passivity and feedback
+passification of smooth discrete-time nonlinear systems by considering their
+piecewise affine approximations. Sufficient conditions are derived for
+passivity and feedback passivity. These results are then extended to systems
+that operate over Gilbert-Elliott type communication channels. As a special
+case, results for feedback passivity of piecewise affine systems over a lossy
+channel are also derived.",2008.02748v1
+2020-08-20,Hyperbolic groups of Fibonacci type and T(5) cyclically presented groups,"Building on previous results concerning hyperbolicity of groups of Fibonacci
+type, we give an almost complete classification of the (non-elementary)
+hyperbolic groups within this class. We are unable to determine the
+hyperbolicity status of precisely two groups, namely the Gilbert-Howie groups
+H(9,4), H(9,7). We show that if H(9,4) is torsion-free then it is not
+hyperbolic. We consider the class of T(5) cyclically presented groups and
+classify the (non-elementary) hyperbolic groups and show that the Tits
+alternative holds.",2008.08986v2
+2020-10-13,Mechanistic Modelling of Chromatin Folding to Understand Function,"Experimental approaches have been applied to address questions in
+understanding three-dimensional chromatin organisation and function. As
+datasets increase in size and complexity, it becomes a challenge to reach a
+mechanistic interpretation of experimental results. Polymer simulations and
+mechanistic modelling have been applied to explain experimental observations,
+and the links to different aspects of genome function. Here, we provide a guide
+for biologists, explaining different simulation approaches and the contexts in
+which they have been used.",2010.06413v1
+2020-12-05,Dual Regularized Optimal Transport,"In this paper, we present a new formulation of unbalanced optimal transport
+called Dual Regularized Optimal Transport (DROT). We argue that regularizing
+the dual formulation of optimal transport results in a version of unbalanced
+optimal transport that leads to sparse solutions and that gives us control over
+mass creation and destruction. We build intuition behind such control and
+present theoretical properties of the solutions to DROT. We demonstrate that
+due to recent advances in optimization techniques, we can feasibly solve such a
+formulation at large scales and present extensive experimental evidence for
+this formulation and its solution.",2012.03126v1
+2020-12-20,Achieving positive rates with predetermined dictionaries,"In the first part of the paper we consider binary input channels that are not
+necessarily stationary and show how positive rates can be achieved using codes
+constrained to be within predetermined dictionaries. We use a
+Gilbert-Varshamov-like argument to obtain the desired rate achieving codes.
+Next we study the corresponding problem for channels with arbitrary alphabets
+and use conflict-set decoding to show that if the dictionaries are contained
+within nice sets, then positive rates are achievable.",2012.10897v1
+2020-12-25,Colossal stability of antiferromagnetically exchange coupled nanomagnets,"Bistable nanomagnets store a binary bit of information. Exchange coupled
+nanomagnets can increase the thermal stability at low dimensions. Here we show
+that the antiferromagnetically (AFM) coupled nanomagnets can be highly stable
+at low dimensions than that of the ferromagnetically (FM) coupled nanomagnets.
+By solving stochastic Landau-Lifshitz-Gilbert equation of magnetization
+dynamics at room temperature, we analyze the stability of the exchange coupled
+nanomagnets in the presence of correlated, uncorrelated, and anti-correlated
+noise. The results show that the correlated noise can make the stability of the
+AFM coupled nanomagnets very high. Such finding will lead to very high-density
+non-volatile storage and logic devices in our future information processing
+systems.",2012.13590v1
+2021-03-08,Cutoff for the Asymmetric Riffle Shuffle,"In the Gilbert-Shannon-Reeds shuffle, a deck of $N$ cards is cut into two
+approximately equal parts which are then riffled uniformly at random. Bayer and
+Diaconis famously showed that this Markov chain undergoes cutoff in total
+variation after $\frac{3\log(N)}{2 \log(2)}$ shuffles. We establish cutoff for
+the more general asymmetric riffle shuffles in which one cuts the deck into
+differently sized parts before riffling. The value of the cutoff point confirms
+a conjecture of Lalley from 2000. Some appealing consequences are that
+asymmetry always slows mixing and that total variation mixing is strictly
+faster than separation and $L^{\infty}$ mixing.",2103.05068v3
+2021-03-24,Information Freshness Analysis of Slotted ALOHA in Gilbert-Elliot Channels,"This letter analyzes a class of information freshness metrics for large IoT
+systems in which terminals employ slotted ALOHA to access a common channel.
+Considering a Gilbert- Elliot channel model, information freshness is evaluated
+through a penalty function that follows a power law of the time elapsed since
+the last received update, in contrast with the linear growth of age of
+information. By means of a signal flow graph analysis of Markov processes, we
+provide exact closed form expressions for the average penalty and for the peak
+penalty violation probability.",2103.13346v2
+2021-04-30,Micromagnetic modeling of magnon coherent states in a nonuniform magnetic field,"The study of the dynamics of magnetically ordered states in strong excitation
+through micromagnetic modeling has become relevant due to the observation of
+magnon Bose condensation. In particular, the question has arisen about the
+possibility of describing the coherent quantum state by the quasi-classical
+Landau-Lifshitz-Gilbert equations. We performed micromagnetic simulations of
+magnetization precession with a high angle of deviation in an out-of-plane
+nonuniform dc field. Our results confirm the formation of coherent magnon state
+under conditions of high excitation. This coherent state extends over long
+distances and described by a spatially inhomogeneous amplitude and a
+homogeneous precession phase.",2104.14804v1
+2021-07-07,Superconducting Magnets,"Superconductivity allows to construct and operate magnets at field values
+beyond 2 Tesla, the practical limitation of normal-conducting magnets
+exploiting ferro-magnetism. The field of superconducting magnets is dominated
+by the field generated in the coil. The stored energy and the electromagnetic
+forces generated by the coil are the main challenges to be overcome in the
+design of these magnets. For further reading you may consult the following
+books: [1], [2], [3], [4] or the proceedings of two specialized CAS courses:
+[5] and [6].",2107.03177v1
+2021-08-14,An Experimental-Design Perspective on Population Genetic Variation,"We consider the hypothesis that Evolution promotes population-wide genome
+patterns that, under randomization, ensures the External Validity of
+adaptations across population members. An adaptation is Externally Valid (EV)
+if its effect holds under a wide range of population genetic variations. A
+prediction following the hypothesis is that pairwise base substitutions in
+segregating regions must be 'random' as in Erdos-Renyi-Gilbert random graphs,
+but with edge probabilities derived from Experimental-Design concepts. We
+demonstrate these probabilities, and consequent mutation rates, in the
+full-genomes of 2504 humans, 1135 flowering plants, 1170 flies, 453 domestic
+sheep and 1223 brown rats.",2108.06580v1
+2021-12-14,Extending the team with a project-specific bot,"While every other software team is adopting off-the-shelf bots to automate
+everyday tasks, the Coq team has made a different choice by developing and
+maintaining a project-specific bot from the ground up. In this article, we
+describe the reasons for this choice, what kind of automation this has allowed
+us to implement, how the many features of this custom bot have evolved based on
+internal feedback, and the technology and architecture choices that have made
+it possible.",2112.07365v1
+2021-12-29,Multi-Adversarial Safety Analysis for Autonomous Vehicles,"This work in progress considers reachability-based safety analysis in the
+domain of autonomous driving in multi-agent systems. We formulate the safety
+problem for a car following scenario as a differential game and study how
+different modelling strategies yield very different behaviors regardless of the
+validity of the strategies in other scenarios. Given the nature of real-life
+driving scenarios, we propose a modeling strategy in our formulation that
+accounts for subtle interactions between agents, and compare its Hamiltonian
+results to other baselines. Our formulation encourages reduction of
+conservativeness in Hamilton-Jacobi safety analysis to provide better safety
+guarantees during navigation.",2112.14344v1
+2022-01-26,Analyzing Ta-Shma's Code via the Expander Mixing Lemma,"Random walks in expander graphs and their various derandomizations (e.g.,
+replacement/zigzag product) are invaluable tools from pseudorandomness.
+Recently, Ta-Shma used s-wide replacement walks in his breakthrough
+construction of a binary linear code almost matching the Gilbert-Varshamov
+bound (STOC 2017). Ta-Shma's original analysis was entirely linear algebraic,
+and subsequent developments have inherited this viewpoint. In this work, we
+rederive Ta-Shma's analysis from a combinatorial point of view using repeated
+application of the expander mixing lemma. We hope that this alternate
+perspective will yield a better understanding of Ta-Shma's construction. As an
+additional application of our techniques, we give an alternate proof of the
+expander hitting set lemma.",2201.11166v1
+2022-02-15,Further Collapses in TFNP,"We show $\textsf{EOPL}=\textsf{PLS}\cap\textsf{PPAD}$. Here the class
+$\textsf{EOPL}$ consists of all total search problems that reduce to the
+End-of-Potential-Line problem, which was introduced in the works by Hubacek and
+Yogev (SICOMP 2020) and Fearnley et al. (JCSS 2020). In particular, our result
+yields a new simpler proof of the breakthrough collapse
+$\textsf{CLS}=\textsf{PLS}\cap\textsf{PPAD}$ by Fearnley et al. (STOC 2021). We
+also prove a companion result $\textsf{SOPL}=\textsf{PLS}\cap\textsf{PPADS}$,
+where $\textsf{SOPL}$ is the class associated with the Sink-of-Potential-Line
+problem.",2202.07761v2
+2022-03-19,A proposed test of quantum mechanics with three connected atomic clock transitions,"We consider possible extensions to quantum mechanics proposed by Steven
+Weinberg, and re-analyze his prediction of a new test based upon three atomic
+clocks in the same atom. We propose realistic experimental systems where this
+hypothesis can be tested. Two systems already set limits on deviations from
+quantum mechanics, while with another system, one would be able to search for
+new physics at the limit of sensitivity of the best atomic clocks.",2203.10269v3
+2022-06-14,Generalized graph splines and the Universal Difference Property,"We study the generalized graph splines introduced by Gilbert, Tymoczko, and
+Viel and focus on an attribute known as the Universal Difference Property
+(UDP). We prove that paths, trees, and cycles satisfy UDP. We explore UDP on
+graphs pasted at a single vertex and use Pr\""ufer domains to illustrate that
+not every edge labeled graph satisfies UDP. We show that UDP must hold for any
+edge labeled graph over a ring $R$ if and only if $R$ is a Pr\""ufer domain.
+Lastly, we prove that UDP is preserved by isomorphisms of edge labeled graphs.",2206.06981v2
+2022-08-04,Total stability and Auslander-Reiten theory for Dynkin quivers,"This paper concerns stability functions for Dynkin quivers, in the generality
+introduced by Rudakov. We show that relatively few inequalities need to be
+satisfied for a stability function to be totally stable (i.e. to make every
+indecomposable stable). Namely, a stability function $\mu$ is totally stable if
+and only if $\mu(\tau V) < \mu(V)$ for every almost split sequences $0 \to \tau
+V \to E \to V \to 0$ where $E$ is indecomposable. These can be visualized as
+those sequences around the ""border"" of the Auslander-Reiten quiver.",2208.02445v1
+2022-09-09,Magnetization dynamics and reversal of two-dimensional magnets,"Micromagnetics simulation based on the classical Landau-Lifshitz-Gilbert
+(LLG) equation has long been a powerful method for modeling magnetization
+dynamics and reversal of three-dimensional (3D) magnets. For two-dimensional
+(2D) magnets, the magnetization reversal always accompanies the collapse of the
+magnetization even at low temperatures due to intrinsic strong spin
+fluctuation. We propose a micromagnetic theory that explicitly takes into
+account the rapid demagnetization and remagnetization dynamics of 2D magnets
+during magnetization reversal. We apply the theory to a single-domain magnet to
+illustrate fundamental differences in magnetization trajectories and reversal
+times for 2D and 3D magnets.",2209.04483v1
+2022-11-06,Two-Qutrit entanglement: 56-years old algorithm challenges machine learning,"Classifying states as entangled or separable is a highly challenging task,
+while it is also one of the foundations of quantum information processing
+theory. This task is higly nontrivial even for relatively simple cases, such as
+two-qutrit Bell-diagonal states, i.e., mixture of nine mutually orthogonal
+maximally entangled states. In this article we apply the Gilbert algorithm to
+revise previously obtained results for this class. In particular we use
+``cartography of entanglement'' to argue that most states left in [Hiesmayr, B.
+C. {\em Scientific Reports} {\bf 11}, 19739 (2021)] as unknown to be entangled
+or separable are most likely indeed separable, or very weakly entangled. The
+presented technique can find endless applications in more general cases.",2211.03213v1
+2022-12-07,Quantitative CLTs on the Poisson space via Skorohod estimates and $p$-Poincaré inequalities,"We establish new explicit bounds on the Gaussian approximation of Poisson
+functionals based on novel estimates of moments of Skorohod integrals.
+Combining these with the Malliavin-Stein method, we derive bounds in the
+Wasserstein and Kolmogorov distances whose application requires minimal moment
+assumptions on add-one cost operators $\unicode{x2014}$ thereby extending the
+results from (Last, Peccati and Schulte, 2016). Our applications include a CLT
+for the Online Nearest Neighbour graph, whose validity was conjectured in
+(Wade, 2009; Penrose and Wade, 2009). We also apply our techniques to derive
+quantitative CLTs for edge functionals of the Gilbert graph, of the $k$-Nearest
+Neighbour graph and of the Radial Spanning Tree, both in cases where
+qualitative CLTs are known and unknown.",2212.03782v1
+2022-12-19,Bounds on Mixed Codes with Finite Alphabets,"Mixed codes, which are error-correcting codes in the Cartesian product of
+different-sized spaces, model degrading storage systems well. While such codes
+have previously been studied for their algebraic properties (e.g., existence of
+perfect codes) or in the case of unbounded alphabet sizes, we focus on the case
+of finite alphabets, and generalize the Gilbert-Varshamov, sphere-packing,
+Elias-Bassalygo, and first linear programming bounds to that setting. In the
+latter case, our proof is also the first for the non-symmetric mono-alphabetic
+$q$-ary case using Navon and Samorodnitsky's Fourier-analytic approach.",2212.09314v1
+2023-02-17,Codes Correcting Burst and Arbitrary Erasures for Reliable and Low-Latency Communication,"Motivated by modern network communication applications which require low
+latency, we study codes that correct erasures with low decoding delay. We
+provide a simple explicit construction that yields convolutional codes that can
+correct both burst and arbitrary erasures under a maximum decoding delay
+constraint $T$. Our proposed code has efficient encoding/decoding algorithms
+and requires a field size that is linear in $T$. We study the performance of
+our code over the Gilbert-Elliot channel; our simulation results show
+significant performance gains over low-delay codes existing in the literature.",2302.08644v1
+2023-03-10,On the coherence of one-relator groups and their group algebras,"We prove that one-relator groups are coherent, solving a well-known problem
+of Gilbert Baumslag. Our proof strategy is readily applicable to many classes
+of groups of cohomological dimension two. We show that fundamental groups of
+two-complexes with non-positive immersions are homologically coherent, we show
+that groups with staggered presentations and many Coxeter groups are coherent
+and we show that group algebras over fields of characteristic zero of groups
+with reducible presentations without proper powers are coherent.",2303.05976v3
+2023-05-11,Linear Codes with Prescribed Hull Dimension and Minimum Distance,"The hull of a linear code (i.e., a finite field vector space)~\({\mathcal
+C}\) is defined to be the vector space formed by the intersection
+of~\({\mathcal C}\) with its dual~\({\mathcal C}^{\perp}.\) Constructing vector
+spaces with a specified hull dimension has important applications and it is
+therefore of interest to study minimum distance properties of such spaces. In
+this paper, we use the probabilistic method to obtain spaces with a given hull
+dimension and minimum distance and also derive Gilbert-Varshamov type
+sufficient conditions for their existence.",2305.07140v1
+2023-05-18,Bounds on Size of Homopolymer Free Codes,"For any given alphabet of size $q$, a Homopolymer Free code (HF code) refers
+to an $(n, M, d)_q$ code of length $n$, size $M$ and minimum Hamming distance
+$d$, where all the codewords are homopolymer free sequences. For any given
+alphabet, this work provides upper and lower bounds on the maximum size of any
+HF code using Sphere Packing bound and Gilbert-Varshamov bound. Further, upper
+and lower bounds on the maximum size of HF codes for various HF code families
+are calculated. Also, as a specific case, upper and lower bounds are obtained
+on the maximum size of homopolymer free DNA codes.",2305.10741v1
+2023-06-08,A Macroscopic Theory of Saturated Ferromagnetic Conductors,"A phenomenological theory of rigid and saturated ferromagnetic conductors is
+constructed from a four-continuum model consisting of a rigid lattice
+continuum, a bound charge continuum for polarization, a circulating current
+continuum for magnetization, and a free charge continuum for electrical
+conduction. The basic laws of physics are applied to the four continua. Thermal
+couplings and the related dissipative effects are also included. The theory
+includes the Landau-Lifshitz-Gilbert equation as one of a system of
+simultaneous equations.",2306.11525v1
+2023-07-02,Unveiling Stable One-dimensional Magnetic Solitons in Magnetic Bilayers,"We propose a novel model which efficiently describes the magnetization
+dynamics in a magnetic bilayer system. By applying a particular gauge
+transformation to the Landau-Lifshitz-Gilbert (LLG) equation, we successfully
+convert the model into an exactly integrable framework. Thus the obtained
+analytical solutions allows us to predict a 1D magnetic soliton pair existed by
+tunning the thickness of the spacing layer between the two ferrimagnetic
+layers. The decoupling-unlocking-locking transition of soliton motion is
+determined at various interaction intensitiy. Our results have implications for
+the manipulation of magnetic solitons and the design of magnetic soliton-based
+logic devices.",2307.00471v1
+2023-09-22,Characterizing Smooth Safety Filters via the Implicit Function Theorem,"Optimization-based safety filters, such as control barrier function (CBF)
+based quadratic programs (QPs), have demonstrated success in controlling
+autonomous systems to achieve complex goals. These CBF-QPs can be shown to be
+continuous, but are generally not smooth, let alone continuously
+differentiable. In this paper, we present a general characterization of smooth
+safety filters -- smooth controllers that guarantee safety in a minimally
+invasive fashion -- based on the Implicit Function Theorem. This
+characterization leads to families of smooth universal formulas for
+safety-critical controllers that quantify the conservatism of the resulting
+safety filter, the utility of which is demonstrated through illustrative
+examples.",2309.12614v1
+2023-09-23,Sphaleron rate from lattice QCD,"We compute the sphaleron rate on the lattice from the inversion of the
+Euclidean time correlators of the topological charge density, performing also
+controlled continuum and zero-smoothing extrapolations. The correlator
+inversion is performed by means of a recently-proposed modification of the
+Backus-Gilbert method.",2309.13327v1
+2023-09-23,"CA-PCA: Manifold Dimension Estimation, Adapted for Curvature","The success of algorithms in the analysis of high-dimensional data is often
+attributed to the manifold hypothesis, which supposes that this data lie on or
+near a manifold of much lower dimension. It is often useful to determine or
+estimate the dimension of this manifold before performing dimension reduction,
+for instance. Existing methods for dimension estimation are calibrated using a
+flat unit ball. In this paper, we develop CA-PCA, a version of local PCA based
+instead on a calibration of a quadratic embedding, acknowledging the curvature
+of the underlying manifold. Numerous careful experiments show that this
+adaptation improves the estimator in a wide range of settings.",2309.13478v1
+2023-11-13,Dedukti: a Logical Framework based on the $λ$$Π$-Calculus Modulo Theory,"Dedukti is a Logical Framework based on the $\lambda$$\Pi$-Calculus Modulo
+Theory. We show that many theories can be expressed in Dedukti: constructive
+and classical predicate logic, Simple type theory, programming languages, Pure
+type systems, the Calculus of inductive constructions with universes, etc. and
+that permits to used it to check large libraries of proofs developed in other
+proof systems: Zenon, iProver, FoCaLiZe, HOL Light, and Matita.",2311.07185v1
+2023-12-24,Sphaleron rate as an inverse problem: a novel lattice approach,"We compute the sphaleron rate on the lattice. We adopt a novel strategy based
+on the extraction of the spectral density via a modified version of the
+Backus-Gilbert method from finite-lattice-spacing and finite-smoothing-radius
+Euclidean topological charge density correlators. The physical sphaleron rate
+is computed by performing controlled continuum limit and zero-smoothing
+extrapolations both in pure gauge and, for the first time, in full QCD.",2312.15468v1
+2005-05-20,On the expansion of the power of any polynomial 1+x+x^2+x^3+x^4+etc,"In this paper, Euler gives the general trionomial coefficient as a sum of the
+binomial coefficients, the general quadrinomial coefficient as a sum of the
+binomial and trinomial coefficients, the general quintonomial coefficient as a
+sum of the binomial and quadrinomial coefficients, and gives a general
+determination of the coefficients of the expansion of any polynomial
+(1+x+x^2+...+x^m)^n as a sum of the coefficients of lower degree polynomial
+coefficients.",0505425v1
+2023-12-05,Central limit theorem for the average closure coefficient,"Many real-world networks exhibit the phenomenon of edge clustering, which is
+typically measured by the average clustering coefficient. Recently, an
+alternative measure, the average closure coefficient, is proposed to quantify
+local clustering. It is shown that the average closure coefficient possesses a
+number of useful properties and can capture complementary information missed by
+the classical average clustering coefficient. In this paper, we study the
+asymptotic distribution of the average closure coefficient of a heterogeneous
+Erd\""{o}s-R\'{e}nyi random graph. We prove that the standardized average
+closure coefficient converges in distribution to the standard normal
+distribution. In the Erd\""{o}s-R\'{e}nyi random graph, the variance of the
+average closure coefficient exhibits the same phase transition phenomenon as
+the average clustering coefficient.",2312.03142v1
+1999-12-17,Expectations For an Interferometric Sunyaev-Zel'dovich Effect Survey for Galaxy Clusters,"Non-targeted surveys for galaxy clusters using the Sunyaev-Zel'dovich effect
+(SZE) will yield valuable information on both cosmology and evolution of the
+intra-cluster medium (ICM). The redshift distribution of detected clusters will
+constrain cosmology, while the properties of the discovered clusters will be
+important for studies of the ICM and galaxy formation. Estimating survey yields
+requires a detailed model for both cluster properties and the survey strategy.
+We address this by making mock observations of galaxy clusters in cosmological
+hydrodynamical simulations. The mock observatory consists of an interferometric
+array of ten 2.5 m diameter telescopes, operating at a central frequency of 30
+GHz with a bandwidth of 8 GHz. We find that clusters with a mass above $2.5
+\times 10^{14} h_{50}^{-1} M_\odot$ will be detected at any redshift, with the
+exact limit showing a very modest redshift dependence. Using a Press-Schechter
+prescription for evolving the number densities of clusters with redshift, we
+determine that such a survey should find hundreds of galaxy clusters per year,
+many at high redshifts and relatively low mass -- an important regime uniquely
+accessible to SZE surveys. Currently favored cosmological models predict
+roughly 25 clusters per square degree.",9912364v2
+2000-02-17,K-Band Spectroscopy of an Obscured Massive Stellar Cluster in the Antennae Galaxies (NGC 4038/4039) with NIRSPEC,"We present infrared spectroscopy of the Antennae Galaxies (NGC 4038/4039)
+with NIRSPEC at the W. M. Keck Observatory. We imaged the star clusters in the
+vicinity of the southern nucleus (NGC 4039) in 0.39"" seeing in K-band using
+NIRSPEC's slit-viewing camera. The brightest star cluster revealed in the
+near-IR (M_K(0) = -17.9) is insignificant optically, but coincident with the
+highest surface brightness peak in the mid-IR (12-18 um) ISO image presented by
+Mirabel et al (1998). We obtained high signal-to-noise 2.03-2.45 um spectra of
+the nucleus and the obscured star cluster at R = 1900.
+  The cluster is very young (age ~ 4 Myr), massive (M ~ 16E6 M_sun), and
+compact (density ~ 115 M_sun pc^(-3) within a 32 pc half-light radius),
+assuming a Salpeter IMF (0.1-100 M_sun). Its hot stars have a radiation field
+characterized by T_eff ~ 39,000 K, and they ionize a compact HII region with
+n_e ~ 10^4 cm^(-3). The stars are deeply embedded in gas and dust (A_V = 9-10
+mag), and their strong FUV field powers a clumpy photodissociation region with
+densities n_H > 10^5 cm^(-3) on scales of ~ 200 pc, radiating L{H_2 1-0 S(1)}=
+9600 L_sun.",0002357v1
+2003-02-20,The Reionization History at High Redshifts II: Estimating the Optical Depth to Thomson Scattering from CMB Polarization,"In light of the recent inference of a high optical depth to Thomson
+scattering, tau, from the WMAP data we investigate the effects of extended
+periods of partial ionization and ask if the value of tau inferred by assuming
+a single sharp transition is an unbiased estimate. We construct and consider
+several representative ionization models and evaluate their signatures in the
+CMB. If tau is estimated with a single sharp transition we show that there can
+be a significant bias in the derived value (and therefore a bias in sigma8 as
+well). For WMAP noise levels the bias in tau is smaller than the statistical
+uncertainty, but for Planck or a cosmic variance limited experiment the tau
+bias could be much larger than the statistical uncertainties. This bias can be
+reduced in the ionization models we consider by fitting a slightly more
+complicated ionization history, such as a two-step ionization process. Assuming
+this two-step process we find the Planck satellite can simultaneously determine
+the initial redshift of reionization to +-2 and tau to +-0.01 Uncertainty about
+the ionization history appears to provide a limit of about 0.005 on how well
+tau can be estimated from CMB polarization data, much better than expected from
+WMAP but significantly worse than expected from cosmic-variance limits.",0302404v2
+2007-02-27,The Sunyaev-Zeldovich Background,"The cosmic background due to the Sunyaev-Zeldovich (SZ) effect is expected to
+be the largest signal at mm and cm wavelengths at a resolution of a few
+arcminutes. We investigate some simple statistics of SZ maps and their scaling
+with the normalization of the matter power spectrum, sigma_8, as well as the
+effects of the unknown physics of the intracluster medium on these statistics.
+We show that the SZ background provides a significant background for SZ cluster
+searches, with the onset of confusion occurring around 10^{14} h^{-1} solar
+masses in a cosmology-dependent way, where confusion is defined as typical
+errors in recovered flux larger than 20%. The confusion limit, corresponds to
+the mass at which there are roughly ten clusters per square degree, with this
+number nearly independent of cosmology and cluster gas physics. Typical errors
+grow quickly as lower mass objects are included in the catalog.
+  We also point out that there is nothing in particular about the rms of the
+filtered map that makes it especially well-suited for capturing aspects of the
+SZ effect, and other indicators of the one-point SZ probability distribution
+function are at least as well suited for the task. For example, the full width
+at half maximum of the one point probability distribution has a field-to-field
+scatter that is about 60% that of the rms.
+  The simplest statistics of SZ maps are largely unaffected by cluster physics
+such aspreheating, although the impact of preheating is clear by eye in the
+maps.Studies aimed at learning about the physics of the intracluster medium
+will apparently require more specialized statistical indicators.",0702727v1
+1998-01-23,An Analytical Construction of the SRB Measures for Baker-type Maps,"For a class of dynamical systems, called the axiom-A systems, Sinai, Ruelle
+and Bowen showed the existence of an invariant measure (SRB measure) weakly
+attracting the temporal average of any initial distribution that is absolutely
+continuous with respect to the Lebesgue measure. Recently, the SRB measures
+were found to be related to the nonequilibrium stationary state distribution
+functions for thermostated or open systems. Inspite of the importance of these
+SRB measures, it is difficult to handle them analytically because they are
+often singular functions. In this article, for three kinds of Baker-type maps,
+the SRB measures are analytically constructed with the aid of a functional
+equation, which was proposed by de Rham in order to deal with a class of
+singular functions. We first briefly review the properties of singular
+functions including those of de Rham. Then, the Baker-type maps are described,
+one of which is non-conservative but time reversible, the second has a
+Cantor-like invariant set, and the third is a model of a simple chemical
+reaction $R \leftrightarrow I \leftrightarrow P$. For the second example, the
+cases with and without escape are considered. For the last example, we consider
+the reaction processes in a closed system and in an open system under a flux
+boundary condition. In all cases, we show that the evolution equation of the
+distribution functions partially integrated over the unstable direction is very
+similar to de Rham's functional equation and, employing this analogy, we
+explicitly construct the SRB measures.",9801031v2
+1998-04-08,Entropy Production : From Open Volume Preserving to Dissipative Systems,"We generalize Gaspard's method for computing the \epsilon-entropy production
+rate in Hamiltonian systems to dissipative systems with attractors considered
+earlier by T\'el, Vollmer, and Breymann. This approach leads to a natural
+definition of a coarse grained Gibbs entropy which is extensive, and which can
+be expressed in terms of the SRB measures and volumes of the coarse graining
+sets which cover the attractor. One can also study the entropy and entropy
+production as functions of the degree of resolution of the coarse graining
+process, and examine the limit as the coarse graining size approaches zero. We
+show that this definition of the Gibbs entropy leads to a positive rate of
+irreversible entropy production for reversible dissipative systems. We apply
+the method to the case of a two dimensional map, based upon a model considered
+by Vollmer, T\'el and Breymann, that is a deterministic version of a
+biased-random walk. We treat both volume preserving and dissipative versions of
+the basic map, and make a comparison between the two cases. We discuss the
+\epsilon-entropy production rate as a function of the size of the coarse
+graining cells for these biased-random walks and, for an open system with flux
+boundary conditions, show regions of exponential growth and decay of the rate
+of entropy production as the size of the cells decreases. This work describes
+in some detail the relation between the results of Gaspard, those of T\'el,
+Vollmer and Breymann, and those of Ruelle, on entropy production in various
+systems described by Anosov or Anosov-like maps.",9804009v2
+1998-07-23,A priori bounds for co-dimension one isometric embeddings,"We prove a priori bounds for the trace of the second fundamental form of a
+$C^4$ isometric embedding into $R^{n+1}$ of a metric $g$ of non-negative
+sectional curvature on $S^n$, in terms of the scalar curvature, and the
+diameter of $g$. These estimates give a bound on the extrinsic geometry in
+terms of intrinsic quantities. They generalize estimates originally obtained by
+Weyl for the case $n=2$ and positive curvature, and then by P. Guan and the
+first author for non-negative curvature and $n=2$. Using $C^{2,\alpha}$
+interior estimates of Evans and Krylov for concave fully nonlinear elliptic
+partial differential equations, these bounds allow us to obtain the following
+convergence theorem: For any $\epsilon>0$, the set of metrics of non-negative
+sectional curvature and scalar curvature bounded below by $\epsilon$ which are
+isometrically embedable in Euclidean space $R^{n+1}$ is closed in the H\""older
+space $C^{4,\alpha}$, $0<\alpha<1$. These results are obtained in an effort to
+understand the following higher dimensional version of the Weyl embedding
+problem which we propose: \emph{Suppose that $g$ is a smooth metric of
+non-negative sectional curvature and positive scalar curvature on \S^n$ which
+is locally isometrically embeddable in $R^{n+1}$. Does $(S^n,g)$ then admit a
+smooth global isometric embedding into $R^{n+1}$?}",9807130v1
+2002-07-02,Active and Passive Fields in Turbulent Transport: the Role of Statistically Preserved Structures,"We have recently proposed that the statistics of active fields (which affect
+the velocity field itself) in well-developed turbulence are also dominated by
+the Statistically Preserved Structures of auxiliary passive fields which are
+advected by the same velocity field. The Statistically Preserved Structures are
+eigenmodes of eigenvalue 1 of an appropriate propagator of the decaying
+(unforced) passive field, or equivalently, the zero modes of a related
+operator. In this paper we investigate further this surprising finding via two
+examples, one akin to turbulent convection in which the temperature is the
+active scalar, and the other akin to magneto-hydrodynamics in which the
+magnetic field is the active vector. In the first example, all the even
+correlation functions of the active and passive fields exhibit identical
+scaling behavior. The second example appears at first sight to be a
+counter-example: the statistical objects of the active and passive fields have
+entirely different scaling exponents. We demonstrate nevertheless that the
+Statistically Preserved Structures of the passive vector dominate again the
+statistics of the active field, except that due to a dynamical conservation law
+the amplitude of the leading zero mode cancels exactly. The active vector is
+then dominated by the sub-leading zero mode of the passive vector. Our work
+thus suggests that the statistical properties of active fields in turbulence
+can be understood with the same generality as those of passive fields.",0207005v1
+2001-06-07,"Secrecy, Computational Loads and Rates in Practical Quantum Cryptography","A number of questions associated with practical implementations of quantum
+cryptography systems having to do with unconditional secrecy, computational
+loads and effective secrecy rates in the presence of perfect and imperfect
+sources are discussed. The different types of unconditional secrecy, and their
+relationship to general communications security, are discussed in the context
+of quantum cryptography. In order to actually carry out a quantum cryptography
+protocol it is necessary that sufficient computational resources be available
+to perform the various processing steps, such as sifting, error correction,
+privacy amplification and authentication. We display the full computer machine
+instruction requirements needed to support a practical quantum cryptography
+implementation. We carry out a numerical comparison of system performance
+characteristics for implementations that make use of either weak coherent
+sources of light or perfect single photon sources, for eavesdroppers making
+individual attacks on the quantum channel characterized by different levels of
+technological capability. We find that, while in some circumstances it is best
+to employ perfect single photon sources, in other situations it is preferable
+to utilize weak coherent sources. In either case the secrecy level of the final
+shared cipher is identical, with the relevant distinguishing figure-of-merit
+being the effective throughput rate.",0106043v2
+2001-08-02,Privacy Amplification in Quantum Key Distribution: Pointwise Bound versus Average Bound,"In order to be practically useful, quantum cryptography must not only provide
+a guarantee of secrecy, but it must provide this guarantee with a useful,
+sufficiently large throughput value. The standard result of generalized privacy
+amplification yields an upper bound only on the average value of the mutual
+information available to an eavesdropper. Unfortunately this result by itself
+is inadequate for cryptographic applications. A naive application of the
+standard result leads one to incorrectly conclude that an acceptable upper
+bound on the mutual information has been achieved. It is the pointwise value of
+the bound on the mutual information, associated with the use of some specific
+hash function, that corresponds to actual implementations. We provide a fully
+rigorous mathematical derivation that shows how to obtain a cryptographically
+acceptable upper bound on the actual, pointwise value of the mutual
+information. Unlike the bound on the average mutual information, the value of
+the upper bound on the pointwise mutual information and the number of bits by
+which the secret key is compressed are specified by two different parameters,
+and the actual realization of the bound in the pointwise case is necessarily
+associated with a specific failure probability. The constraints amongst these
+parameters, and the effect of their values on the system throughput, have not
+been previously analyzed. We show that the necessary shortening of the key
+dictated by the cryptographically correct, pointwise bound, can still produce
+viable throughput rates that will be useful in practice.",0108013v1
+2008-03-27,Assessing surrogate endpoints in vaccine trials with case-cohort sampling and the Cox model,"Assessing immune responses to study vaccines as surrogates of protection
+plays a central role in vaccine clinical trials. Motivated by three ongoing or
+pending HIV vaccine efficacy trials, we consider such surrogate endpoint
+assessment in a randomized placebo-controlled trial with case-cohort sampling
+of immune responses and a time to event endpoint. Based on the principal
+surrogate definition under the principal stratification framework proposed by
+Frangakis and Rubin [Biometrics 58 (2002) 21--29] and adapted by Gilbert and
+Hudgens (2006), we introduce estimands that measure the value of an immune
+response as a surrogate of protection in the context of the Cox proportional
+hazards model. The estimands are not identified because the immune response to
+vaccine is not measured in placebo recipients. We formulate the problem as a
+Cox model with missing covariates, and employ novel trial designs for
+predicting the missing immune responses and thereby identifying the estimands.
+The first design utilizes information from baseline predictors of the immune
+response, and bridges their relationship in the vaccine recipients to the
+placebo recipients. The second design provides a validation set for the
+unmeasured immune responses of uninfected placebo recipients by immunizing them
+with the study vaccine after trial closeout. A maximum estimated likelihood
+approach is proposed for estimation of the parameters. Simulated data examples
+are given to evaluate the proposed designs and study their properties.",0803.3919v1
+2008-06-13,The Formation and Evolution of Massive Stellar Clusters in IC 4662,"We present a multiwavelength study of the formation of massive stellar
+clusters, their emergence from cocoons of gas and dust, and their feedback on
+surrounding matter. Using data that span from radio to optical wavelengths,
+including Spitzer and Hubble ACS observations, we examine the population of
+young star clusters in the central starburst region of the irregular Wolf-Rayet
+galaxy IC 4662. We model the radio-to-IR spectral energy distributions of
+embedded clusters to determine the properties of their HII regions and dust
+cocoons (sizes, masses, densities, temperatures), and use near-IR and optical
+data with mid-IR spectroscopy to constrain the properties of the embedded
+clusters themselves (mass, age, extinction, excitation, abundance). The two
+massive star-formation regions in IC 4662 are excited by stellar populations
+with ages of ~ 4 million years and masses of ~ 3 x 10^5 M_sun (assuming a
+Kroupa IMF). They have high excitation and sub-solar abundances, and they may
+actually be comprised of several massive clusters rather than the single
+monolithic massive compact objects known as Super Star Clusters (SSCs). Mid-IR
+spectra reveal that these clusters have very high extinctions, A_V ~ 20-25 mag,
+and that the dust in IC 4662 is well-mixed with the emitting gas, not in a
+foreground screen.",0806.2302v1
+2009-01-28,Searching for Main-Belt Comets Using the Canada-France-Hawaii Telescope Legacy Survey,"The Canada-France-Hawaii Telescope Legacy Survey, specifically the Very Wide
+segment of data, is used to search for possible main-belt comets. In the first
+data set, 952 separate objects with asteroidal orbits within the main-belt are
+examined using a three-level technique. First, the full-width-half-maximum of
+each object is compared to stars of similar magnitude, to look for evidence of
+a coma. Second, the brightness profiles of each object are compared with three
+stars of the same magnitude, which are nearby on the image to ensure any
+extended profile is not due to imaging variations. Finally, the star profiles
+are subtracted from the asteroid profile and the residuals are compared with
+the background using an unpaired T-test. No objects in this survey show
+evidence of cometary activity. The second survey includes 11438 objects in the
+main-belt, which are examined visually. One object, an unknown comet, is found
+to show cometary activity. Its motion is consistent with being a main-belt
+asteroid, but the observed arc is too short for a definitive orbit calculation.
+No other body in this survey shows evidence of cometary activity. Upper limits
+of the number of weakly and strongly active main-belt comets are derived to be
+630+/-77 and 87+/-28, respectively. These limits are consistent with those
+expected from asteroid collisions. In addition, data extracted from the
+Canada-France-Hawaii Telescope image archive of main-belt comet 176P/LINEAR is
+presented.",0901.4511v1
+2009-10-02,Spectroscopic Observations of New Oort Cloud Comet 2006 VZ13 and Four Other Comets,"Spectral data are presented for comets 2006 VZ13 (LINEAR), 2006 K4 (NEAT),
+2006 OF2 (Broughton), 2P/Encke, and 93P/Lovas I, obtained with the Cerro-Tololo
+Inter-American Observatory 1.5-m telescope in August 2007. Comet 2006 VZ13 is a
+new Oort cloud comet and shows strong lines of CN (3880 angstroms), the Swan
+band sequence for C_2 (4740, 5160, and 5630 angstroms), C_3 (4056 angstroms),
+and other faint species. Lines are also identified in the spectra of the other
+comets. Flux measurements of the CN, C_2 (Delta v = +1,0), and C_3 lines are
+recorded for each comet and production rates and ratios are derived. When
+considering the comets as a group, there is a correlation of C_2 and C_3
+production with CN, but there is no conclusive evidence that the production
+rate ratios depend on heliocentric distance. The continuum is also measured,
+and the dust production and dust-to-gas ratios are calculated. There is a
+general trend, for the group of comets, between the dust-to-gas ratio and
+heliocentric distance, but it does not depend on dynamical age or class. Comet
+2006 VZ13 is determined to be in the carbon-depleted (or Tempel 1 type) class.",0910.0416v1
+2009-12-01,Approximate Sparse Recovery: Optimizing Time and Measurements,"An approximate sparse recovery system consists of parameters $k,N$, an
+$m$-by-$N$ measurement matrix, $\Phi$, and a decoding algorithm, $\mathcal{D}$.
+Given a vector, $x$, the system approximates $x$ by $\widehat x
+=\mathcal{D}(\Phi x)$, which must satisfy $\| \widehat x - x\|_2\le C \|x -
+x_k\|_2$, where $x_k$ denotes the optimal $k$-term approximation to $x$. For
+each vector $x$, the system must succeed with probability at least 3/4. Among
+the goals in designing such systems are minimizing the number $m$ of
+measurements and the runtime of the decoding algorithm, $\mathcal{D}$.
+  In this paper, we give a system with $m=O(k \log(N/k))$
+measurements--matching a lower bound, up to a constant factor--and decoding
+time $O(k\log^c N)$, matching a lower bound up to $\log(N)$ factors.
+  We also consider the encode time (i.e., the time to multiply $\Phi$ by $x$),
+the time to update measurements (i.e., the time to multiply $\Phi$ by a
+1-sparse $x$), and the robustness and stability of the algorithm (adding noise
+before and after the measurements). Our encode and update times are optimal up
+to $\log(N)$ factors.",0912.0229v1
+2010-04-07,Concatenated quantum codes can attain the quantum Gilbert-Varshamov bound,"A family of quantum codes of increasing block length with positive rate is
+asymptotically good if the ratio of its distance to its block length approaches
+a positive constant. The asymptotic quantum Gilbert-Varshamov (GV) bound states
+that there exist $q$-ary quantum codes of sufficiently long block length $N$
+having fixed rate $R$ with distance at least $N H^{-1}_{q^2}((1-R)/2)$, where
+$H_{q^2}$ is the $q^2$-ary entropy function. For $q < 7$, only random quantum
+codes are known to asymptotically attain the quantum GV bound. However, random
+codes have little structure. In this paper, we generalize the classical result
+of Thommesen to the quantum case, thereby demonstrating the existence of
+concatenated quantum codes that can asymptotically attain the quantum GV bound.
+The outer codes are quantum generalized Reed-Solomon codes, and the inner codes
+are random independently chosen stabilizer codes, where the rates of the inner
+and outer codes lie in a specified feasible region.",1004.1127v6
+2010-09-02,Stable and unstable regimes in higher-dimensional convex billiards with cylindrical shape,"We introduce a class of convex, higher-dimensional billiard models which
+generalise stadium billiards. These models correspond to the free motion of a
+point-particle in a region bounded by cylinders cut by planes. They are
+motivated by models of particles interacting via a string-type mechanism, and
+confined by hard walls. The combination of these elements may give rise to a
+defocusing mechanism, similar to that in two dimensions, which allows large
+chaotic regions in phase space. The remaining part of phase space is associated
+with marginally stable behaviour. In fact periodic orbits in these systems
+generically come in continuous parametric families, sociated with a pair of
+parabolic eigen-directions: the periodic orbits are unstable in the presence of
+a defocusing mechanism, but marginally stable otherwise. By performing the
+stability analysis of families of periodic orbits at a nonlinear level, we
+establish the conditions under which families are nonlinearly stable or
+unstable. As a result, we identify regions in the parameter space of the models
+which admit non-linearly stable oscillations in the form of whispering gallery
+modes. Where no families of periodic orbits are stable, the billiards are
+completely chaotic, i.e.\ the Lyapunov exponents of the billiard map are
+non-zero.",1009.0337v1
+2011-08-29,"Magnetization Dynamics, Throughput and Energy Dissipation in a Universal Multiferroic Nanomagnetic Logic Gate with Fan-in and Fan-out","The switching dynamics of a multiferroic nanomagnetic NAND gate with
+fan-in/fan-out is simulated by solving the Landau-Lifshitz-Gilbert (LLG)
+equation while neglecting thermal fluctuation effects. The gate and logic wires
+are implemented with dipole-coupled 2-phase (magnetostrictive/piezoelectric)
+multiferroic elements that are clocked with electrostatic potentials of ~50 mV
+applied to the piezoelectric layer generating 10 MPa stress in the
+magnetostrictive layers for switching. We show that a pipeline bit throughput
+rate of ~ 0.5 GHz is achievable with proper magnet layout and sinusoidal
+four-phase clocking. The gate operation is completed in 2 ns with a latency of
+4 ns. The total (internal + external) energy dissipated for a single gate
+operation at this throughput rate is found to be only ~ 1000 kT in the gate and
+~3000 kT in the 12-magnet array comprising two input and two output wires for
+fan-in and fan-out. This makes it respectively 3 and 5 orders of magnitude more
+energy-efficient than complementary-metal-oxide-semiconductor-transistor (CMOS)
+based and spin-transfer-torque-driven nanomagnet based NAND gates. Finally, we
+show that the dissipation in the external clocking circuit can always be
+reduced asymptotically to zero using increasingly slow adiabatic clocking, such
+as by designing the RC time constant to be 3 orders of magnitude smaller than
+the clocking period. However, the internal dissipation in the device must
+remain and cannot be eliminated if we want to perform fault-tolerant classical
+computing.
+  Keywords: Nanomagnetic logic, multiferroics, straintronics and spintronics,
+Landau-Lifshitz-Gilbert equation.",1108.5758v1
+2011-09-15,Stato evolutivo delle stelle della Cintura di Orione ed implicazioni archeoastronomiche,"In the present work it is evaluated the evolutionary state of the Orion Belt
+stars, an asterism very important for the ancient Egyptians, finding that, when
+the pyramids were built, the brightness of the three stars of the Belt was
+practically the same as today. This not trivial result has important
+implications in the framework of the so-called Orion Correlation Theory, a
+controversial theory proposed by Bauval and Gilbert (1994), according to which
+a perfect coincidence would exist between the disposition of the three stars of
+the Orion Belt and that of the main Giza pyramids, so that the latter would
+represent the monumental reproduction on the ground of that important asterism.
+  ----
+  Nel presente lavoro viene determinato lo stato evolutivo delle stelle della
+Cintura di Orione, ricavando che, all'epoca della costruzione delle piramidi,
+la luminosita' delle tre stelle della Cintura era di fatto uguale a quella
+odierna. Tale non banale risultato riveste una importanza fondamentale
+nell'ambito della verifica della controversa Teoria della Correlazione di
+Orione proposta da Bauval e Gilbert nel 1994, secondo la quale esisterebbe una
+perfetta coincidenza tra la disposizione delle tre stelle della Cintura e
+quella delle tre piramidi nella piana di Giza.",1109.3284v2
+2012-07-31,Surface Acoustic Wave-Driven Ferromagnetic Resonance in Nickel Thin Films: Theory and Experiment,"We present an extensive experimental and theoretical study of surface
+acoustic wave-driven ferromagnetic resonance. In a first modeling approach
+based on the Landau-Lifshitz-Gilbert equation, we derive expressions for the
+magnetization dynamics upon magnetoelastic driving that are used to calculate
+the absorbed microwave power upon magnetic resonance as well as the spin
+current density generated by the precessing magnetization in the vicinity of a
+ferromagnet/normal metal interface. In a second modeling approach, we deal with
+the backaction of the magnetization dynamics on the elastic wave by solving the
+elastic wave equation and the Landau-Lifshitz-Gilbert equation
+selfconsistently, obtaining analytical solutions for the acoustic wave phase
+shift and attenuation. We compare both modeling approaches with the complex
+forward transmission of a LiNbO$_3$/Ni surface acoustic wave hybrid device
+recorded experimentally as a function of the external magnetic field
+orientation and magnitude, rotating the field within three different planes and
+employing three different surface acoustic wave frequencies. We find
+quantitative agreement of the experimentally observed power absorption and
+surface acoustic wave phase shift with our modeling predictions using one set
+of parameters for all field configurations and frequencies.",1208.0001v1
+2012-09-27,Vortex Lattices in the Superconducting Phases of Doped Topological Insulators and Heterostructures,"Majorana fermions are predicted to play a crucial role in condensed matter
+realizations of topological quantum computation. These heretofore undiscovered
+quasiparticles have been predicted to exist at the cores of vortex excitations
+in topological superconductors and in heterostructures of superconductors and
+materials with strong spin-orbit coupling. In this work we examine topological
+insulators with bulk s-wave superconductivity in the presence of a
+vortex-lattice generated by a perpendicular magnetic field. Using
+self-consistent Bogoliubov-de Gennes, calculations we confirm that beyond the
+semi-classical, weak-pairing limit that the Majorana vortex states appear as
+the chemical potential is tuned from either side of the band edge so long as
+the density of states is sufficient for superconductivity to form. Further, we
+demonstrate that the previously predicted vortex phase transition survives
+beyond the semi-classical limit. At chemical potential values smaller than the
+critical chemical potential, the vortex lattice modes hybridize within the top
+and bottom surfaces giving rise to a dispersive low-energy mid-gap band. As the
+chemical potential is increased, the Majorana states become more localized
+within a single surface but spread into the bulk toward the opposite surface.
+Eventually, when the chemical potential is sufficiently high in the bulk bands,
+the Majorana modes can tunnel between surfaces and eventually a critical point
+is reached at which modes on opposite surfaces can freely tunnel and annihilate
+leading to the topological phase transition previously studied in the work of
+Hosur et al.",1209.6373v1
+2013-04-23,L2/L2-foreach sparse recovery with low risk,"In this paper, we consider the ""foreach"" sparse recovery problem with failure
+probability $p$. The goal of which is to design a distribution over $m \times
+N$ matrices $\Phi$ and a decoding algorithm $\algo$ such that for every
+$\vx\in\R^N$, we have the following error guarantee with probability at least
+$1-p$ \[\|\vx-\algo(\Phi\vx)\|_2\le C\|\vx-\vx_k\|_2,\] where $C$ is a constant
+(ideally arbitrarily close to 1) and $\vx_k$ is the best $k$-sparse
+approximation of $\vx$.
+  Much of the sparse recovery or compressive sensing literature has focused on
+the case of either $p = 0$ or $p = \Omega(1)$. We initiate the study of this
+problem for the entire range of failure probability. Our two main results are
+as follows: \begin{enumerate} \item We prove a lower bound on $m$, the number
+measurements, of $\Omega(k\log(n/k)+\log(1/p))$ for $2^{-\Theta(N)}\le p <1$.
+Cohen, Dahmen, and DeVore \cite{CDD2007:NearOptimall2l2} prove that this bound
+is tight. \item We prove nearly matching upper bounds for \textit{sub-linear}
+time decoding. Previous such results addressed only $p = \Omega(1)$.
+\end{enumerate}
+  Our results and techniques lead to the following corollaries: (i) the first
+ever sub-linear time decoding $\lolo$ ""forall"" sparse recovery system that
+requires a $\log^{\gamma}{N}$ extra factor (for some $\gamma<1$) over the
+optimal $O(k\log(N/k))$ number of measurements, and (ii) extensions of Gilbert
+et al. \cite{GHRSW12:SimpleSignals} results for information-theoretically
+bounded adversaries.",1304.6232v1
+2013-11-28,"Starbugs: all-singing, all-dancing fibre positioning robots","Starbugs are miniature piezoelectric 'walking' robots with the ability to
+simultaneously position many optical fibres across a telescope's focal plane.
+Their simple design incorporates two piezoceramic tubes to form a pair of
+concentric 'legs' capable of taking individual steps of a few microns, yet with
+the capacity to move a payload several millimetres per second. The Australian
+Astronomical Observatory has developed this technology to enable fast and
+accurate field reconfigurations without the inherent limitations of more
+traditional positioning techniques, such as the 'pick and place' robotic arm.
+We report on our recent successes in demonstrating Starbug technology, driven
+principally by R&D efforts for the planned MANIFEST (many instrument
+fibre-system) facility for the Giant Magellan Telescope. Significant
+performance gains have resulted from improvements to the Starbug system,
+including i) the use of a vacuum to attach Starbugs to the underside of a
+transparent field plate, ii) optimisation of the control electronics, iii) a
+simplified mechanical design with high sensitivity piezo actuators, and iv) the
+construction of a dedicated laboratory 'test rig'. A method of reliably
+rotating Starbugs in steps of several arcminutes has also been devised, which
+integrates with the pre-existing x-y movement directions and offers greater
+flexibility while positioning. We present measured performance data from a
+prototype system of 10 Starbugs under full (closed-loop control), at field
+plate angles of 0-90 degrees.",1311.7371v1
+2014-02-05,Magnetization dynamics: path-integral formalism for the stochastic Landau-Lifshitz-Gilbert equation,"We construct a path-integral representation of the generating functional for
+the dissipative dynamics of a classical magnetic moment as described by the
+stochastic generalization of the Landau-Lifshitz-Gilbert equation proposed by
+Brown, with the possible addition of spin-torque terms. In the process of
+constructing this functional in the Cartesian coordinate system, we critically
+revisit this stochastic equation. We present it in a form that accommodates for
+any discretization scheme thanks to the inclusion of a drift term. The
+generalized equation ensures the conservation of the magnetization modulus and
+the approach to the Gibbs-Boltzmann equilibrium in the absence of non-potential
+and time-dependent forces. The drift term vanishes only if the mid-point
+Stratonovich prescription is used. We next reset the problem in the more
+natural spherical coordinate system. We show that the noise transforms
+non-trivially to spherical coordinates acquiring a non-vanishing mean value in
+this coordinate system, a fact that has been often overlooked in the
+literature. We next construct the generating functional formalism in this
+system of coordinates for any discretization prescription. The functional
+formalism in Cartesian or spherical coordinates should serve as a starting
+point to study different aspects of the out-of-equilibrium dynamics of magnets.
+Extensions to colored noise, micro-magnetism and disordered problems are
+straightforward.",1402.1200v2
+2014-10-17,The fixed irreducible bridge ensemble for self-avoiding walks,"We define a new ensemble for self-avoiding walks in the upper half-plane, the
+fixed irredicible bridge ensemble, by considering self-avoiding walks in the
+upper half-plane up to their $n$-th bridge height, $Y_n$, and scaling the walk
+by $1/Y_n$ to obtain a curve in the unit strip, and then taking $n\to\infty$.
+We then conjecture a relationship between this ensemble to $\SLE$ in the unit
+strip from $0$ to a fixed point along the upper boundary of the strip,
+integrated over the conjectured exit density of self-avoiding walk spanning a
+strip in the scaling limit. We conjecture that there exists a positive constant
+$\sigma$ such that $n^{-\sigma}Y_n$ converges in distribution to that of a
+stable random variable as $n\to\infty$. Then the conjectured relationship
+between the fixed irreducible bridge scaling limit and $\SLE$ can be described
+as follows: If one takes a SAW considered up to $Y_n$ and scales by $1/Y_n$ and
+then weights the walk by $Y_n$ to an appropriate power, then in the limit
+$n\to\infty$, one should obtain a curve from the scaling limit of the
+self-avoiding walk spanning the unit strip. In addition to a heuristic
+derivation, we provide numerical evidence to support the conjecture and give
+estimates for the boundary scaling exponent.",1410.4796v1
+2014-11-20,Type II Seesaw Higgsology and LEP/LHC constraints,"In the {\sl type II seesaw} model, if spontaneous violation of the lepton
+number conservation prevails over that of explicit violation, a rich Higgs
+sector phenomenology is expected to arise with light scalar states having mixed
+charged-fermiophobic/neutrinophilic properties. We study the constraints on
+these light CP-even ($h^0$) and CP-odd ($A^0$) states from LEP exclusion
+limits, combined with the so far established limits and properties of the
+$125-126$~GeV ${\cal H}$ boson discovered at the LHC. We show that, apart from
+a fine-tuned region of the parameter space, masses in the $\sim 44$ to $80$ GeV
+range escape from the LEP limits if the vacuum expectation value of the Higgs
+triplet is $\lesssim {\cal O}(10^{-3})$GeV, that is comfortably in the region
+for 'natural' generation of Majorana neutrino masses within this model. In the
+lower part of the scalar mass spectrum the decay channels ${\cal H} \to h^0
+h^0, A^0 A^0$ lead predominantly to heavy flavor plus missing energy or to
+totally invisible Higgs decays, mimicking dark matter signatures without a dark
+matter candidate. Exclusion limits at the percent level of these
+(semi-)invisible decay channels would be needed, together with stringent bounds
+on the (doubly-)charged states, to constrain significantly this scenario. We
+also revisit complementary constraints from ${\cal H} \to \gamma \gamma$ and
+${\cal H} \to Z \gamma$ channels on the (doubly)charged scalar sector of the
+model, pinpointing non-sensitivity regions, and carry out a likeliness study
+for the theoretically allowed couplings in the scalar potential.",1411.5645v1
+2015-01-11,Epidemic Threshold of an SIS Model in Dynamic Switching Networks,"In this paper, we analyze dynamic switching networks, wherein the networks
+switch arbitrarily among a set of topologies. For this class of dynamic
+networks, we derive an epidemic threshold, considering the SIS epidemic model.
+First, an epidemic probabilistic model is developed assuming independence
+between states of nodes. We identify the conditions under which the epidemic
+dies out by linearizing the underlying dynamical system and analyzing its
+asymptotic stability around the origin. The concept of joint spectral radius is
+then used to derive the epidemic threshold, which is later validated using
+several networks (Watts-Strogatz, Barabasi-Albert, MIT reality mining graphs,
+Regular, and Gilbert). A simplified version of the epidemic threshold is
+proposed for undirected networks. Moreover, in the case of static networks, the
+derived epidemic threshold is shown to match conventional analytical results.
+Then, analytical results for the epidemic threshold of dynamic networksare
+proved to be applicable to periodic networks. For dynamic regular networks, we
+demonstrate that the epidemic threshold is identical to the epidemic threshold
+for static regular networks. An upper bound for the epidemic spread probability
+in dynamic Gilbert networks is also derived and verified using simulation.",1501.02472v2
+2015-04-29,Entropy measures as geometrical tools in the study of cosmology,"Classical chaos is often characterized as exponential divergence of nearby
+trajectories. In many interesting cases these trajectories can be identified
+with geodesic curves. We define here the entropy by $S = \ln \chi (x)$ with
+$\chi(x)$ being the distance between two nearby geodesics. We derive an
+equation for the entropy which by transformation to a Ricatti-type equation
+becomes similar to the Jacobi equation. We further show that the geodesic
+equation for a null geodesic in a double warped space time leads to the same
+entropy equation. By applying a Robertson-Walker metric for a flat
+three-dimensional Euclidian space expanding as a function of time, we again
+reach the entropy equation stressing the connection between the chosen entropy
+measure and time. We finally turn to the Raychaudhuri equation for expansion,
+which also is a Ricatti equation similar to the transformed entropy equation.
+Those Ricatti-type equations have solutions of the same form as the Jacobi
+equation. The Raychaudhuri equation can be transformed to a harmonic oscillator
+equation, and it has been shown that the geodesic deviation equation of Jacobi
+is essentially equivalent to that of a harmonic oscillator. The Raychaudhuri
+equations are strong geometrical tools in the study of General Relativity and
+Cosmology. We suggest a refined entropy measure applicable in Cosmology and
+defined by the average deviation of the geodesics in a congruence.",1504.07855v2
+2015-06-24,Ebb: A DSL for Physical Simulation on CPUs and GPUs,"Designing programming environments for physical simulation is challenging
+because simulations rely on diverse algorithms and geometric domains. These
+challenges are compounded when we try to run efficiently on heterogeneous
+parallel architectures. We present Ebb, a domain-specific language (DSL) for
+simulation, that runs efficiently on both CPUs and GPUs. Unlike previous DSLs,
+Ebb uses a three-layer architecture to separate (1) simulation code, (2)
+definition of data structures for geometric domains, and (3) runtimes
+supporting parallel architectures. Different geometric domains are implemented
+as libraries that use a common, unified, relational data model. By structuring
+the simulation framework in this way, programmers implementing simulations can
+focus on the physics and algorithms for each simulation without worrying about
+their implementation on parallel computers. Because the geometric domain
+libraries are all implemented using a common runtime based on relations, new
+geometric domains can be added as needed, without specifying the details of
+memory management, mapping to different parallel architectures, or having to
+expand the runtime's interface.
+  We evaluate Ebb by comparing it to several widely used simulations,
+demonstrating comparable performance to hand-written GPU code where available,
+and surpassing existing CPU performance optimizations by up to 9$\times$ when
+no GPU code exists.",1506.07577v3
+2016-04-27,Scoping of material response under DEMO neutron irradiation: comparison with fission and influence of nuclear library selection,"Predictions of material activation inventories will be a key input to
+virtually all aspects of the operation, safety and environmental assessment of
+future fusion nuclear plants. Additionally, the neutron-induced transmutation
+(change) of material composition (inventory) with time, and the creation and
+evolution of configurational damage from atomic displacements, require precise
+quantification because they can lead to significant changes in material
+properties, and thus influence reactor-component lifetime. A comprehensive
+scoping study has been performed to quantify the activation, transmutation
+(depletion and build-up) and immediate damage response under neutron
+irradiation for all naturally occurring elements from hydrogen to bismuth. The
+resulting database provides a global picture of the response of a material,
+covering the majority of nuclear technological space, but focussing
+specifically on typical conditions expected for a demonstration fusion power
+plant (DEMO). Results from fusion are compared against typical fission
+conditions for selected fusion relevant materials, demonstrating that the
+latter cannot be relied upon to give accurate scalable experimental predictions
+of material response in a future fusion reactor. Results from different nuclear
+data libraries are also compared, highlighting the variations and deficiencies.",1604.08496v1
+2016-05-23,Beyond the Interface Limit: Structural and Magnetic Depth Profiles of Voltage-Controlled Magneto-Ionic Heterostructures,"Electric-field control of magnetism provides a promising route towards
+ultralow power information storage and sensor technologies. The effects of
+magneto-ionic motion have so far been prominently featured in the direct
+modification of interface chemical and physical characteristics. Here we
+demonstrate magnetoelectric coupling moderated by voltage-driven oxygen
+migration beyond the interface limit in relatively thick AlOx/GdOx/Co (15 nm)
+films. Oxygen migration and its ramifications on the Co magnetization are
+quantitatively mapped with polarized neutron reflectometry under thermal and
+electro-thermal conditionings. The depth-resolved profiles uniquely identify
+interfacial and bulk behaviors and a semi-reversible suppression and recovery
+of the magnetization. Magnetometry measurements show that the conditioning
+changes the microstructure so as to disrupt long-range ferromagnetic ordering,
+resulting in an additional magnetically soft phase. X-ray spectroscopy confirms
+electric field induced changes in the Co oxidation state but not in the Gd,
+suggesting that the GdOx transmits oxygen but does not source or sink it. These
+results together provide crucial insight into controlling magnetic
+heterostructures via magneto-ionic motion, not only at the interface, but also
+throughout the bulk of the films.",1605.07209v1
+2016-06-02,RankSign: an efficient signature algorithm based on the rank metric,"In this paper we propose a new approach to code-based signatures that makes
+use in particular of rank metric codes. When the classical approach consists in
+finding the unique preimage of a syndrome through a decoding algorithm, we
+propose to introduce the notion of mixed decoding of erasures and errors for
+building signature schemes. In that case the difficult problem becomes, as is
+the case in lattice-based cryptography, finding a preimage of weight above the
+Gilbert-Varshamov bound (case where many solutions occur) rather than finding a
+unique preimage of weight below the Gilbert-Varshamov bound. The paper
+describes RankSign: a new signature algorithm for the rank metric based on a
+new mixed algorithm for decoding erasures and errors for the recently
+introduced Low Rank Parity Check (LRPC) codes. We explain how it is possible
+(depending on choices of parameters) to obtain a full decoding algorithm which
+is able to find a preimage of reasonable rank weight for any random syndrome
+with a very strong probability. We study the semantic security of our signature
+algorithm and show how it is possible to reduce the unforgeability to direct
+attacks on the public matrix, so that no information leaks through signatures.
+Finally, we give several examples of parameters for our scheme, some of which
+with public key of size $11,520$ bits and signature of size $1728$ bits.
+Moreover the scheme can be very fast for small base fields.",1606.00629v2
+2016-09-09,Image and Video Mining through Online Learning,"Within the field of image and video recognition, the traditional approach is
+a dataset split into fixed training and test partitions. However, the labelling
+of the training set is time-consuming, especially as datasets grow in size and
+complexity. Furthermore, this approach is not applicable to the home user, who
+wants to intuitively group their media without tirelessly labelling the
+content. Our interactive approach is able to iteratively cluster classes of
+images and video. Our approach is based around the concept of an image
+signature which, unlike a standard bag of words model, can express
+co-occurrence statistics as well as symbol frequency. We efficiently compute
+metric distances between signatures despite their inherent high dimensionality
+and provide discriminative feature selection, to allow common and distinctive
+elements to be identified from a small set of user labelled examples. These
+elements are then accentuated in the image signature to increase similarity
+between examples and pull correct classes together. By repeating this process
+in an online learning framework, the accuracy of similarity increases
+dramatically despite labelling only a few training examples. To demonstrate
+that the approach is agnostic to media type and features used, we evaluate on
+three image datasets (15 scene, Caltech101 and FG-NET), a mixed text and image
+dataset (ImageTag), a dataset used in active learning (Iris) and on three
+action recognition datasets (UCF11, KTH and Hollywood2). On the UCF11 video
+dataset, the accuracy is 86.7% despite using only 90 labelled examples from a
+dataset of over 1200 videos, instead of the standard 1122 training videos. The
+approach is both scalable and efficient, with a single iteration over the full
+UCF11 dataset of around 1200 videos taking approximately 1 minute on a standard
+desktop machine.",1609.02770v2
+2016-11-17,Stashing the stops in multijet events at the LHC,"While the presence of a light stop is increasingly disfavored by the
+experimental limits set on R-parity conserving scenarios, the naturalness of
+supersymmetry could still be safely concealed in the more challenging final
+states predicted by the existence of non-null R-parity violating couplings.
+Although R-parity violating signatures are extensively looked for at the Large
+Hadron Collider, these searches always assume 100\% branching ratios for the
+direct decays of supersymmetric particles into Standard Model ones. In this
+paper we scrutinize the implications of relaxing this assumption by focusing on
+one motivated scenario where the lightest stop is heavier than a chargino and a
+neutralino. Considering a class of R-parity baryon number violating couplings,
+we show on general grounds that while the direct decay of the stop into
+Standard Model particles is dominant for large values of these couplings,
+smaller values give rise, instead, to the dominance of a plethora of longer
+decay chains and richer final states that have not yet been analyzed at the
+LHC, thus weakening the impact of the present experimental stop mass limits. We
+characterize the case for R-parity baryon number violating couplings in the
+$10^{-7} - 10^{-1}$ range, in two different benchmark points scenarios within
+the model-independent setting of the low-energy phenomenological Minimal
+Supersymmetric Standard Model. We identify the different relevant experimental
+signatures, estimate the corresponding proton--proton cross sections at
+$\sqrt{s}=14$ TeV and discuss signal versus background issues.",1611.05850v2
+2017-02-18,Inf-sup stable finite-element methods for the Landau--Lifshitz--Gilbert and harmonic map heat flow equation,"In this paper we propose and analyze a finite element method for both the
+harmonic map heat and Landau--Lifshitz--Gilbert equation, the time variable
+remaining continuous. Our starting point is to set out a unified saddle point
+approach for both problems in order to impose the unit sphere constraint at the
+nodes since the only polynomial function satisfying the unit sphere constraint
+everywhere are constants. A proper inf-sup condition is proved for the Lagrange
+multiplier leading to the well-posedness of the unified formulation. \emph{A
+priori} energy estimates are shown for the proposed method.
+  When time integrations are combined with the saddle point finite element
+approximation some extra elaborations are required in order to ensure both
+\emph{a priori} energy estimates for the director or magnetization vector
+depending on the model and an inf-sup condition for the Lagrange multiplier.
+This is due to the fact that the unit length at the nodes is not satisfied in
+general when a time integration is performed. We will carry out a linear Euler
+time-stepping method and a non-linear Crank--Nicolson method. The latter is
+solved by using the former as a non-linear solver.",1702.05588v2
+2017-06-15,Generalized Voltage-based State-Space Modelling of Modular Multilevel Converters with Constant Equilibrium in Steady-State,"This paper demonstrates that the sum and difference of the upper and lower
+arm voltages are suitable variables for deriving a generalized state-space
+model of an MMC which settles at a constant equilibrium in steady-state
+operation, while including the internal voltage and current dynamics. The
+presented modelling approach allows for separating the multiple frequency
+components appearing within the MMC as a first step of the model derivation, to
+avoid variables containing multiple frequency components in steady-state. On
+this basis, it is shown that Park transformations at three different
+frequencies ($+\omega$, $-2\omega$ and $+3\omega$) can be applied for deriving
+a model formulation where all state-variables will settle at constant values in
+steady-state, corresponding to an equilibrium point of the model. The resulting
+model is accurately capturing the internal current and voltage dynamics of a
+three-phase MMC, independently from how the control system is implemented. The
+main advantage of this model formulation is that it can be linearised, allowing
+for eigenvalue-based analysis of the MMC dynamics. Furthermore, the model can
+be utilized for control system design by multi-variable methods requiring any
+stable equilibrium to be defined by a fixed operating point. Time-domain
+simulations in comparison to an established average model of the MMC, as well
+as results from a detailed simulation model of an MMC with 400 sub-modules per
+arm, are presented as verification of the validity and accuracy of the
+developed model.",1706.04959v1
+2017-11-07,Global Properties of M31's Stellar Halo from the SPLASH Survey: III. Measuring the Stellar Velocity Dispersion Profile,"We present the velocity dispersion of red giant branch (RGB) stars in M31's
+halo, derived by modeling the line of sight velocity distribution of over 5000
+stars in 50 fields spread throughout M31's stellar halo. The dataset was
+obtained as part of the SPLASH (Spectroscopic and Photometric Landscape of
+Andromeda's Stellar Halo) Survey, and covers projected radii of 9 to 175 kpc
+from M31's center. All major structural components along the line of sight in
+both the Milky Way (MW) and M31 are incorporated in a Gaussian Mixture Model,
+including all previously identified M31 tidal debris features in the observed
+fields. The probability an individual star is a constituent of M31 or the MW,
+based on a set of empirical photometric and spectroscopic diagnostics, is
+included as a prior probability in the mixture model. The velocity dispersion
+of stars in M31's halo is found to decrease only mildly with projected radius,
+from 108 km/s in the innermost radial bin (8.2 to 14.1 kpc) to $\sim 80$ to 90
+km/s at projected radii of $\sim 40$ to 130 kpc, and can be parameterized with
+a power-law of slope $-0.12\pm 0.05$. The quoted uncertainty on the power-law
+slope reflects only the precision of the method, although other sources of
+uncertainty we consider contribute negligibly to the overall error budget.",1711.02700v1
+2017-12-19,Efficient implementations of the Multivariate Decomposition Method for approximating infinite-variate integrals,"In this paper we focus on efficient implementations of the Multivariate
+Decomposition Method (MDM) for approximating integrals of $\infty$-variate
+functions. Such $\infty$-variate integrals occur for example as expectations in
+uncertainty quantification. Starting with the anchored decomposition $f =
+\sum_{\mathfrak{u}\subset\mathbb{N}} f_\mathfrak{u}$, where the sum is over all
+finite subsets of $\mathbb{N}$ and each $f_\mathfrak{u}$ depends only on the
+variables $x_j$ with $j\in\mathfrak{u}$, our MDM algorithm approximates the
+integral of $f$ by first truncating the sum to some `active set' and then
+approximating the integral of the remaining functions $f_\mathfrak{u}$
+term-by-term using Smolyak or (randomized) quasi-Monte Carlo (QMC) quadratures.
+The anchored decomposition allows us to compute $f_\mathfrak{u}$ explicitly by
+function evaluations of $f$. Given the specification of the active set and
+theoretically derived parameters of the quadrature rules, we exploit structures
+in both the formula for computing $f_\mathfrak{u}$ and the quadrature rules to
+develop computationally efficient strategies to implement the MDM in various
+scenarios. In particular, we avoid repeated function evaluations at the same
+point. We provide numerical results for a test function to demonstrate the
+effectiveness of the algorithm.",1712.06782v3
+2018-05-24,Impact of thermal fluctuations on transport in antiferromagnetic semimetals,"Recent demonstrations on manipulating antiferromagnetic (AF) order have
+triggered a growing interest in antiferromagnetic metal (AFM), and potential
+high-density spintronic applications demand further improvements in the
+anisotropic magnetoresistance (AMR). The antiferromagnetic semimetals (AFS) are
+newly discovered materials that possess massless Dirac fermions that are
+protected by the crystalline symmetries. In this material, a reorientation of
+the AF order may break the underlying symmetries and induce a finite energy
+gap. As such, the possible phase transition from the semimetallic to insulating
+phase gives us a choice for a wide range of resistance ensuring a large AMR. To
+further understand the robustness of the phase transition, we study thermal
+fluctuations of the AF order in AFS at a finite temperature. For macroscopic
+samples, we find that the thermal fluctuations effectively decrease the
+magnitude of the AF order by renormalizing the effective Hamiltonian. Our
+finding suggests that the insulating phase exhibits a gap narrowing at elevated
+temperatures, which leads to a substantial decrease in AMR. We also examine
+spatially correlated thermal fluctuations for microscopic samples by solving
+the microscopic Landau-Lifshitz-Gilbert equation finding a qualitative
+difference of the gap narrowing in the insulating phase. For both cases, the
+semimetallic phase shows a minimal change in its transmission spectrum
+illustrating the robustness of the symmetry protected states in AFS. Our
+finding may serve as a guideline for estimating and maximizing AMR of the AFS
+samples at elevated temperatures.",1805.09826v1
+2018-05-29,An exact solution for choosing the largest measurement from a sample drawn from an uniform distribution,"In ""Recognizing the Maximum of a Sequence"", Gilbert and Mosteller analyze a
+full information game where n measurements from an uniform distribution are
+drawn and a player (knowing n) must decide at each draw whether or not to
+choose that draw. The goal is to maximize the probability of choosing the draw
+that corresponds to the maximum of the sample. In their calculations of the
+optimal strategy, the optimal probability and the asymptotic probability, they
+assume that after a draw x the probability that the next i numbers are all
+smaller than x is $x^i$; but this fails to recognize that continuing the game
+(not choosing a draw because it is lower than a cutoff and waiting for the next
+draw) conditions the distribution of the following i numbers such that their
+expected maximum is higher then i/(i+1). The problem is now redefined with each
+draw leading to a win, a false positive loss, a false negative loss and a
+continuation. An exact formula for these probabilities is deduced, both for the
+general case of n-1 different indifference numbers (assuming 0 as the last
+cutoff) and the particular case of the same indifference number for all cutoffs
+but the last. An approximation is found that preserves the main characteristics
+of the optimal solution (slow decay of win probability, quick decay of false
+positives and linear decay of false negatives). This new solution and the
+original Gilbert and Mosteller formula are compared against simulations, and
+their asymptotic behavior is studied.",1805.11556v1
+2018-06-28,From clusters to queries: exploiting uncertainty in the modularity landscape of complex networks,"Uncovering latent community structure in complex networks is a field that has
+received an enormous amount of attention. Unfortunately, whilst potentially
+very powerful, unsupervised methods for uncovering labels based on topology
+alone has been shown to suffer from several difficulties. For example, the
+search space for many module extraction approaches, such as the modularity
+maximisation algorithm, appears to be extremely glassy, with many high valued
+solutions that lack any real similarity to one another. However, in this paper
+we argue that this is not a flaw with the modularity maximisation algorithm
+but, rather, information that can be used to aid the context specific
+classification of functional relationships between vertices. Formally, we
+present an approach for generating a high value modularity consensus space for
+a network, based on the ensemble space of locally optimal modular partitions.
+We then use this approach to uncover latent relationships, given small query
+sets. The methods developed in this paper are applied to biological and social
+datasets with ground-truth label data, using a small number of examples used as
+seed sets to uncover relationships. When tested on both real and synthetic
+datasets our method is shown to achieve high levels of classification accuracy
+in a context specific manner, with results comparable to random walk with
+restart methods.",1806.10904v1
+2018-07-05,Veloce Rosso: Australia's new precision radial velocity spectrograph,"Veloce is an ultra-stable fibre-fed R4 echelle spectrograph for the 3.9 m
+Anglo-Australian Telescope. The first channel to be commissioned, Veloce
+'Rosso', utilises multiple low-cost design innovations to obtain Doppler
+velocities for Sun-like and M-dwarf stars at <1 m/s precision. The spectrograph
+has an asymmetric white-pupil format with a 100-mm beam diameter, delivering
+R>75,000 spectra over a 580-950 nm range for the Rosso channel. Simultaneous
+calibration is provided by a single-mode pulsed laser frequency comb in tandem
+with a traditional arc lamp. A bundle of 19 object fibres provides a 2.4"" field
+of view for full sampling of stellar targets from the AAT site. Veloce is
+housed in dual environmental enclosures that maintain positive air pressure at
+a stability of +/-0.3 mbar, with a thermal stability of +/-0.01 K on the
+optical bench. We present a technical overview and early performance data from
+Australia's next major spectroscopic machine.",1807.01938v1
+2018-07-19,Generalized Metric Repair on Graphs,"Many modern data analysis algorithms either assume that or are considerably
+more efficient if the distances between the data points satisfy a metric. These
+algorithms include metric learning, clustering, and dimensionality reduction.
+Because real data sets are noisy, the similarity measures often fail to satisfy
+a metric. For this reason, Gilbert and Jain [11] and Fan, et al. [8] introduce
+the closely related problems of $\textit{sparse metric repair}$ and
+$\textit{metric violation distance}$. The goal of each problem is to repair as
+few distances as possible to ensure that the distances between the data points
+satisfy a metric. We generalize these problems so as to no longer require all
+the distances between the data points. That is, we consider a weighted graph
+$G$ with corrupted weights w and our goal is to find the smallest number of
+modifications to the weights so that the resulting weighted graph distances
+satisfy a metric. This problem is a natural generalization of the sparse metric
+repair problem and is more flexible as it takes into account different
+relationships amongst the input data points. As in previous work, we
+distinguish amongst the types of repairs permitted (decrease, increase, and
+general repairs). We focus on the increase and general versions and establish
+hardness results and show the inherent combinatorial structure of the problem.
+We then show that if we restrict to the case when $G$ is a chordal graph, then
+the problem is fixed parameter tractable. We also present several classes of
+approximation algorithms. These include and improve upon previous metric repair
+algorithms for the special case when $G = K_n$",1807.07619v1
+2018-10-17,Precipitating Ordered Skyrmion Lattices from Helical Spaghetti,"Magnetic skyrmions have been the focus of intense research due to their
+potential applications in ultra-high density data and logic technologies, as
+well as for the unique physics arising from their antisymmetric exchange term
+and topological protections. In this work we prepare a chiral jammed state in
+chemically disordered (Fe, Co)Si consisting of a combination of
+randomly-oriented magnetic helices, labyrinth domains, rotationally disordered
+skyrmion lattices and/or isolated skyrmions. Using small angle neutron
+scattering, (SANS) we demonstrate a symmetry-breaking magnetic field sequence
+which disentangles the jammed state, resulting in an ordered, oriented skyrmion
+lattice. The same field sequence was performed on a sample of powdered Cu2OSeO3
+and again yields an ordered, oriented skyrmion lattice, despite relatively
+non-interacting nature of the grains. Micromagnetic simulations confirm the
+promotion of a preferred skyrmion lattice orientation after field treatment,
+independent of the initial configuration, suggesting this effect may be
+universally applicable. Energetics extracted from the simulations suggest that
+approaching a magnetic hard axis causes the moments to diverge away from the
+magnetic field, increasing the Dzyaloshinskii-Moriya energy, followed
+subsequently by a lattice re-orientation. The ability to facilitate an emergent
+ordered magnetic lattice with long-range orientation in a variety of materials
+despite overwhelming internal disorder enables the study of skyrmions even in
+imperfect powdered or polycrystalline systems and greatly improves the ability
+to rapidly screen candidate skyrmion materials.",1810.07631v1
+2018-11-09,Post-randomization Biomarker Effect Modification in an HIV Vaccine Clinical Trial,"While the HVTN 505 trial showed no overall efficacy of the tested vaccine to
+prevent HIV infection over placebo, previous studies, biological theories, and
+the finding that immune response markers strongly correlated with infection in
+vaccine recipients generated the hypothesis that a qualitative interaction
+occurred. This hypothesis can be assessed with statistical methods for studying
+treatment effect modification by an intermediate response variable (i.e.,
+principal stratification effect modification (PSEM) methods). However,
+available PSEM methods make untestable structural risk assumptions, such that
+assumption-lean versions of PSEM methods are needed in order to surpass the
+high bar of evidence to demonstrate a qualitative interaction. Fortunately, the
+survivor average causal effect (SACE) literature is replete with
+assumption-lean methods that can be readily adapted to the PSEM application for
+the special case of a binary intermediate response variable. We map this
+adaptation, opening up a host of new PSEM methods for a binary intermediate
+variable measured via two-phase sampling, for a dichotomous or failure time
+final outcome and including or excluding the SACE monotonicity assumption. The
+new methods support that the vaccine partially protected vaccine recipients
+with a high polyfunctional CD8+ T cell response, an important new insight for
+the HIV vaccine field.",1811.03930v1
+2019-03-22,Natural reward as the fundamental macroevolutionary force,"Darwin's theory of evolution by natural selection does not predict long-term
+progress or advancement, nor does it provide a useful way to define or
+understand these concepts. Nevertheless, the history of life is marked by major
+trends that appear progressive, and seemingly more advanced forms of life have
+appeared. To reconcile theory and fact, evolutionists have proposed novel
+theories that extend natural selection to levels and time frames not justified
+by the original structure of Darwin's theory. To extend evolutionary theory
+without violating the most basic tenets of Darwinism, I here identify a
+separate struggle and an alternative evolutionary force. Owing to the abundant
+free energy in our universe, there is a struggle for supremacy that naturally
+rewards those that are first to invent novelties that allow exploitation of
+untapped resources. This natural reward comes in form of a temporary monopoly,
+which is granted to those who win a competitive race to innovate. By analogy to
+human economies, natural selection plays the role of nature's inventor,
+gradually fashioning inventions to the situation at hand, while natural reward
+plays the role of nature's entrepreneur, choosing which inventions to first
+disseminate to large markets. Natural reward leads to progress through a
+process of invention-conquest macroevolution, in which the dual forces of
+natural selection and natural reward create and disseminate major innovations.
+Over vast time frames, natural reward drives the advancement of life by a
+process of extinction-replacement megaevolution that releases constraints on
+progress and increases the innovativeness of life.",1903.09567v1
+2019-07-15,Entanglement-assisted Quantum Codes from Algebraic Geometry Codes,"Quantum error correcting codes play the role of suppressing noise and
+decoherence in quantum systems by introducing redundancy. Some strategies can
+be used to improve the parameters of these codes. For example, entanglement can
+provide a way for quantum error correcting codes to achieve higher rates than
+the one obtained via the traditional stabilizer formalism. Such codes are
+called entanglement-assisted quantum (QUENTA) codes. In this paper, we use
+algebraic geometry codes to construct several families of QUENTA codes via the
+Euclidean and the Hermitian construction. Two of the families created have
+maximal entanglement and have quantum Singleton defect equal to zero or one.
+Comparing the other families with the codes with the respective quantum
+Gilbert-Varshamov bound, we show that our codes have a rate that surpasses that
+bound. At the end, asymptotically good towers of linear complementary dual
+codes are used to obtain asymptotically good families of maximal entanglement
+QUENTA codes. Furthermore, a simple comparison with the quantum
+Gilbert-Varshamov bound demonstrates that using our construction it is possible
+to create an asymptotically family of QUENTA codes that exceeds this bound.",1907.06357v2
+2019-09-06,Parameter identification for the Landau-Lifshitz-Gilbert equation in Magnetic Particle Imaging,"Magnetic particle imaging (MPI) is a tracer-based technique for medical
+imaging where the tracer consists of ironoxide nanoparticles. The key idea is
+to measure the particle response to a temporally changing external magnetic
+field to compute the spatial concentration of the tracer inside the object. A
+decent mathematical model demands for a data-driven computation of the system
+function which does not only describe the measurement geometry but also encodes
+the interaction of the particles with the external magnetic field. The physical
+model of this interaction is given by the Landau-Lifshitz-Gilbert (LLG)
+equation. The determination of the system function can be seen as an inverse
+problem of its own which can be interpreted as a calibration problem for MPI.
+In this contribution the calibration problem is formulated as an inverse
+parameter identification problem for the LLG equation. We give a detailed
+analysis of the direct as well as the inverse problem in an all-at-once as well
+as in a reduced setting. The analytical results yield a deeper understanding of
+inverse problems connected to the LLG equation and provide a starting point for
+the development of robust numerical solution methods in MPI.",1909.02912v1
+2019-11-06,Automated Left Ventricle Dimension Measurement in 2D Cardiac Ultrasound via an Anatomically Meaningful CNN Approach,"Two-dimensional echocardiography (2DE) measurements of left ventricle (LV)
+dimensions are highly significant markers of several cardiovascular diseases.
+These measurements are often used in clinical care despite suffering from large
+variability between observers. This variability is due to the challenging
+nature of accurately finding the correct temporal and spatial location of
+measurement endpoints in ultrasound images. These images often contain fuzzy
+boundaries and varying reflection patterns between frames. In this work, we
+present a convolutional neural network (CNN) based approach to automate 2DE LV
+measurements. Treating the problem as a landmark detection problem, we propose
+a modified U-Net CNN architecture to generate heatmaps of likely coordinate
+locations. To improve the network performance we use anatomically meaningful
+heatmaps as labels and train with a multi-component loss function. Our network
+achieves 13.4%, 6%, and 10.8% mean percent error on intraventricular septum
+(IVS), LV internal dimension (LVID), and LV posterior wall (LVPW) measurements
+respectively. The design outperforms other networks and matches or approaches
+intra-analyser expert error.",1911.02448v1
+2019-11-12,Linear-mode avalanche photodiode arrays for low-noise near-infrared imaging in space,"Astronomical observations often require the detection of faint signals in the
+presence of noise, and the near-infrared regime is no exception. In particular,
+where the application has short exposure time constraints, we are frequently
+and unavoidably limited by the read noise of a system. A recent and
+revolutionary development in detector technology is that of linear-mode
+avalanche photodiode (LmAPD) arrays. By the introduction of a signal
+multiplication region within the device, effective read noise can be reduced to
+<0.2 e-, enabling the detection of very small signals at frame rates of up to 1
+kHz. This is already impacting ground-based astronomy in high-speed
+applications such as wavefront sensing and fringe tracking, but has not yet
+been exploited for scientific space missions. We present the current status of
+a collaboration with Leonardo MW - creators of the 'SAPHIRA' LmAPD array - as
+we work towards the first in-orbit demonstration of a SAPHIRA device in 'Emu',
+a hosted payload on the International Space Station. The Emu mission will fully
+benefit from the 'noiseless' gains offered by LmAPD technology as it produces a
+time delay integration photometric sky survey at 1.4 microns, using compact
+readout electronics developed at the Australian National University. This is
+just one example of a use case that could not be achieved with conventional
+infrared sensors.",1911.04684v1
+2020-03-17,Maximizing Influence-based Group Shapley Centrality,"One key problem in network analysis is the so-called influence maximization
+problem, which consists in finding a set $S$ of at most $k$ seed users, in a
+social network, maximizing the spread of information from $S$. This paper
+studies a related but slightly different problem: We want to find a set $S$ of
+at most $k$ seed users that maximizes the spread of information, when $S$ is
+added to an already pre-existing - but unknown - set of seed users $T$. We
+consider such scenario to be very realistic. Assume a central entity wants to
+spread a piece of news, while having a budget to influence $k$ users. This
+central authority may know that some users are already aware of the information
+and are going to spread it anyhow. The identity of these users being however
+completely unknown. We model this optimization problem using the Group Shapley
+value, a well-founded concept from cooperative game theory. While the standard
+influence maximization problem is easy to approximate within a factor
+$1-1/e-\epsilon$ for any $\epsilon>0$, assuming common computational complexity
+conjectures, we obtain strong hardness of approximation results for the problem
+at hand in this paper. Maybe most prominently, we show that it cannot be
+approximated within $1/n^{o(1)}$ under the Gap Exponential Time Hypothesis.
+Hence, it is unlikely to achieve anything better than a polynomial factor
+approximation. Nevertheless, we show that a greedy algorithm can achieve a
+factor of $\frac{1-1/e}{k}-\epsilon$ for any $\epsilon>0$, showing that not all
+is lost in settings where $k$ is bounded.",2003.07966v1
+2020-04-24,Single-electron operation of a silicon-CMOS 2x2 quantum dot array with integrated charge sensing,"The advanced nanoscale integration available in silicon complementary
+metal-oxide-semiconductor (CMOS) technology provides a key motivation for its
+use in spin-based quantum computing applications. Initial demonstrations of
+quantum dot formation and spin blockade in CMOS foundry-compatible devices are
+encouraging, but results are yet to match the control of individual electrons
+demonstrated in university-fabricated multi-gate designs. We show here that the
+charge state of quantum dots formed in a CMOS nanowire device can be sensed by
+using floating gates to electrostatically couple it to a remote single electron
+transistor (SET) formed in an adjacent nanowire. By biasing the nanowire and
+gates of the remote SET with respect to the nanowire hosting the quantum dots,
+we controllably form ancillary quantum dots under the floating gates, thus
+enabling the demonstration of independent control over charge transitions in a
+quadruple (2x2) quantum dot array. This device overcomes the limitations
+associated with measurements based on tunnelling transport through the dots and
+permits the sensing of all charge transitions, down to the last electron in
+each dot. We use effective mass theory to investigate the necessary
+optimization of the device parameters in order to achieve the tunnel rates
+required for spin-based quantum computation.",2004.11558v1
+2020-08-22,Measurement of magnetic fields using the voltage generated by a vibrating wire,"A vibrating wire may be used as an instrument with a variety of applications,
+one of which is the measurement of magnetic fields. Often, the magnetic fields
+are determined by measuring the amplitude of the wire vibration under the
+action of a Lorentz force. Though generally adequate, this approach may be
+inconvenient in certain circumstances. One of these occurs when it is necessary
+to measure the amplitude of high-frequency vibration, as the amplitude is
+expected to decrease linearly with frequency, and thus becomes harder to
+measure. Another example may be found in situations where the sensor must
+operate over a wide range of vibration frequencies. In this case the sensor
+will be unresponsive to specific frequencies of wire vibration, which are
+determined by the placement of the sensor. This means that for the instrument
+to be robust, the sensor must be precisely mobile, or multiple sensors must be
+used.
+  Here a technique which may be used to supplement the displacement sensor is
+described. This technique makes use of the voltage generated by the motion of
+the wire in the magnetic field under measurement. It is predicted that the
+technique may be more suitable for measurements requiring high frequency
+vibration, and is sensitive to all frequencies of vibration. Measurements of a
+magnetic field obtained using this technique are compared to those found using
+only a displacement sensor, and the benefits and drawbacks of the technique are
+discussed.",2008.09898v1
+2020-11-25,Domain wall motion in axially symmetric spintronic nanowires,"This article is concerned with the dynamics of magnetic domain walls (DWs) in
+nanowires as solutions to the classical Landau-Lifschitz-Gilbert equation
+augmented by a typically non-variational Slonczewski term for spin-torque
+effects. Taking applied field and spin-polarization as the primary parameters,
+we study dynamic stability as well as selection mechanisms analytically and
+numerically in an axially symmetric setting. Concerning the stability of the
+DWs' asymptotic states, we distinguish the bistable (both stable) and the
+monostable (one unstable, one stable) parameter regime. In the bistable regime,
+we extend known stability results of an explicit family of precessing solutions
+and identify a relation of applied field and spin-polarization for standing
+DWs. We verify that this family is convectively unstable into the monostable
+regime, thus forming so-called pushed fronts, before turning absolutely
+unstable. In the monostable regime, we present explicit formulas for the
+so-called absolute spectrum of more general matrix operators. This allows us to
+relate translation and rotation symmetries to the position of the singularities
+of the pointwise Green's function. Thereby, we determine the linear selection
+mechanism for the asymptotic velocity and frequency of DWs and corroborate
+these by long-time numerical simulations. All these results include the axially
+symmetric Landau-Lifschitz-Gilbert equation.",2012.01343v1
+2020-12-27,Vacuum Stability Conditions for Higgs Potentials with $SU(2)_L$ Triplets,"Tree-level dynamical stability of scalar field potentials in renormalizable
+theories can in principle be expressed in terms of positivity conditions on
+quartic polynomial structures. However, these conditions cannot always be cast
+in a fully analytical resolved form, involving only the couplings and being
+valid for all field directions. In this paper we consider such forms in three
+physically motivated models involving $SU(2)$ triplet scalar fields: the
+Type-II seesaw model, the Georgi-Machacek model, and a generalized two-triplet
+model. A detailed analysis of the latter model allows to establish the full set
+of necessary and sufficient boundedness from below conditions. These can serve
+as a guide, together with unitarity and vacuum structure constraints, for
+consistent phenomenological (tree-level) studies. They also provide a seed for
+improved loop-level conditions, and encompass in particular the leading ones
+for the more specific Georgi-Machacek case. Incidentally, we present complete
+proofs of various properties and also derive general positivity conditions on
+quartic polynomials that are equivalent but much simpler than the ones used in
+the literature.",2012.13947v2
+2021-03-25,Phases of Small Worlds: A Mean Field Formulation,"A network is said to have the properties of a small world if a suitably
+defined average distance between any two nodes is proportional to the logarithm
+of the number of nodes, $N$. In this paper, we present a novel derivation of
+the small-world property for Gilbert-Erd\""os-Renyi random networks. We employ a
+mean field approximation that permits the analytic derivation of the
+distribution of shortest paths that exhibits logarithmic scaling away from the
+phase transition, inferable via a suitably interpreted order parameter. We
+begin by framing the problem in generality with a formal generating functional
+for undirected weighted random graphs with arbitrary disorder, recovering the
+result that the free energy associated with an ensemble of Gilbert graphs
+corresponds to a system of non-interacting fermions identified with the edge
+states. We then present a mean field solution for this model and extend it to
+more general realizations of network randomness. For a two family class of
+stochastic block models that we refer to as dimorphic networks, which allow for
+links within the different families to be drawn from two independent discrete
+probability distributions, we find the mean field approximation maps onto a
+spin chain combinatorial problem and again yields useful approximate analytic
+expressions for mean path lengths. Dimorophic networks exhibit a richer phase
+structure, where distinct small world regimes separate in analogy to the
+spinodal decomposition of a fluid. We find that is it possible to induce small
+world behavior in sub-networks that by themselves would not be in the
+small-world regime.",2103.14001v2
+2021-05-04,Evaluating Metrics for Standardized Benchmarking of Remote Presence Systems,"To reduce the need for business-related air travel and its associated energy
+consumption and carbon footprint, the U.S. Department of Energy's ARPA-E is
+supporting a research project called SCOTTIE - Systematic Communication
+Objectives and Telecommunications Technology Investigations and Evaluations.
+SCOTTIE tests virtual and augmented reality platforms in a functional
+comparison with face-to-face (FtF) interactions to derive travel replacement
+thresholds for common industrial training scenarios. The primary goal of Study
+1 is to match the communication effectiveness and learning outcomes obtained
+from a FtF control using virtual reality (VR) training scenarios in which a
+local expert with physical equipment trains a remote apprentice without
+physical equipment immediately present. This application scenario is
+commonplace in industrial settings where access to expensive equipment and
+materials is limited and a number of apprentices must travel to a central
+location in order to undergo training. Supplying an empirically validated
+virtual training alternative constitutes a readily adoptable use-case for
+businesses looking to reduce time and monetary expenditures associated with
+travel. The technology used for three different virtual presence technologies
+was strategically selected for feasibility, relatively low cost, business
+relevance, and potential for impact through transition. The authors suggest
+that the results of this study might generalize to the challenge of virtual
+conferences.",2105.01772v1
+2021-07-12,Partially Concatenated Calderbank-Shor-Steane Codes Achieving the Quantum Gilbert-Varshamov Bound Asymptotically,"In this paper, we utilize a concatenation scheme to construct new families of
+quantum error correction codes achieving the quantum Gilbert-Varshamov (GV)
+bound asymptotically. We concatenate alternant codes with any linear code
+achieving the classical GV bound to construct Calderbank-Shor-Steane (CSS)
+codes. We show that the concatenated code can achieve the quantum GV bound
+asymptotically and can approach the Hashing bound for asymmetric Pauli
+channels. By combing Steane's enlargement construction of CSS codes, we derive
+a family of enlarged stabilizer codes achieving the quantum GV bound for
+enlarged CSS codes asymptotically. As applications, we derive two families of
+fast encodable and decodable CSS codes with parameters
+$\mathscr{Q}_1=[[N,\Omega(\sqrt{N}),\Omega( \sqrt{N})]],$ and
+$\mathscr{Q}_2=[[N,\Omega(N/\log N),\Omega(N/\log N)/\Omega(\log N)]].$ We show
+that $\mathscr{Q}_1$ can be encoded very efficiently by circuits of size $O(N)$
+and depth $O(\sqrt{N})$. For an input error syndrome, $\mathscr{Q}_1$ can
+correct any adversarial error of weight up to half the minimum distance bound
+in $O(N)$ time. $\mathscr{Q}_1$ can also be decoded in parallel in
+$O(\sqrt{N})$ time by using $O(\sqrt{N})$ classical processors. For an input
+error syndrome, we proved that $\mathscr{Q}_2$ can correct a linear number of
+${X}$-errors with high probability and an almost linear number of ${Z}$-errors
+in $O(N )$ time. Moreover, $\mathscr{Q}_2$ can be decoded in parallel in
+$O(\log(N))$ time by using $O(N)$ classical processors.",2107.05174v2
+2021-07-12,Assessment of Immune Correlates of Protection via Controlled Vaccine Efficacy and Controlled Risk,"Immune correlates of protection (CoPs) are immunologic biomarkers accepted as
+a surrogate for an infectious disease clinical endpoint and thus can be used
+for traditional or provisional vaccine approval. To study CoPs in randomized,
+placebo-controlled trials, correlates of risk (CoRs) are first assessed in
+vaccine recipients. This analysis does not assess causation, as a CoR may fail
+to be a CoP. We propose a causal CoP analysis that estimates the controlled
+vaccine efficacy curve across biomarker levels $s$, $CVE(s)$, equal to one
+minus the ratio of the controlled-risk curve $r_C(s)$ at $s$ and placebo risk,
+where $r_C(s)$ is causal risk if all participants are assigned vaccine and the
+biomarker is set to $s$. The criterion for a useful CoP is wide variability of
+$CVE(s)$ in $s$. Moreover, estimation of $r_C(s)$ is of interest in itself,
+especially in studies without a placebo arm. For estimation of $r_C(s)$,
+measured confounders can be adjusted for by any regression method that
+accommodates missing biomarkers, to which we add sensitivity analysis to
+quantify robustness of CoP evidence to unmeasured confounding. Application to
+two harmonized phase 3 trials supports that 50% neutralizing antibody titer has
+value as a controlled vaccine efficacy CoP for virologically confirmed dengue
+(VCD): in CYD14 the point estimate (95% confidence interval) for $CVE(s)$
+accounting for measured confounders and building in conservative margin for
+unmeasured confounding increases from 29.6% (95% CI 3.5 to 45.9) at titer 1:36
+to 78.5% (95% CI 67.9 to 86.8) at titer 1:1200; these estimates are 17.4% (95%
+CI -14.4 to 36.5) and 84.5% (95% CI 79.6 to 89.1) for CYD15.",2107.05734v1
+2021-07-23,"Efficient nonparametric estimation of the covariate-adjusted threshold-response function, a support-restricted stochastic intervention","Identifying a biomarker or treatment-dose threshold that marks a specified
+level of risk is an important problem, especially in clinical trials. This
+risk, viewed as a function of thresholds and possibly adjusted for covariates,
+we call the threshold-response function. Extending the work of Donovan, Hudgens
+and Gilbert (2019), we propose a nonparametric efficient estimator for the
+covariate-adjusted threshold-response function, which utilizes machine learning
+and Targeted Minimum-Loss Estimation (TMLE). We additionally propose a more
+general estimator, based on sequential regression, that also applies when there
+is outcome missingness. We show that the threshold-response for a given
+threshold may be viewed as the expected outcome under a stochastic intervention
+where all participants are given a treatment dose above the threshold. We prove
+the estimator is efficient and characterize its asymptotic distribution. A
+method to construct simultaneous 95% confidence bands for the
+threshold-response function and its inverse is given. Furthermore, we discuss
+how to adjust our estimator when the treatment or biomarker is
+missing-at-random, as is the case in clinical trials with biased sampling
+designs, using inverse-probability-weighting. The methods are assessed in a
+diverse set of simulation settings with rare outcomes and cumulative
+case-control sampling. The methods are employed to estimate neutralizing
+antibody thresholds for virologically confirmed dengue risk in the CYD14 and
+CYD15 dengue vaccine trials.",2107.11459v2
+2021-10-15,The radio SZ effect as a probe of the cosmological radio background,"If there is a substantial cosmological radio background, there should be a
+radio Sunyaev-Zeldovich (SZ) effect that goes along with it. The radio
+background Comptonization leads to a slight photon excess at all wavelengths,
+while Comptonization of the CMB at low frequencies leads to a decrement. For
+levels of the radio background consistent with observations, these effects
+cancel each other around $\nu\simeq 735~$MHz, with an excess at lower
+frequencies and a decrement at higher frequencies. Assuming a purely
+cosmological origin of the observed ARCADE radio excess, at $\nu \lesssim
+20\,{\rm GHz}$ the signal scales as $\Delta T / T_{\rm CMB}\simeq 2\,y\left[
+(\nu/735\,{\rm MHz})^{-2.59}-1\right]$ with frequency and the Compton-$y$
+parameter of the cluster. For a typical cluster, the total radio SZ signal is
+at the level of $\Delta T\simeq 1\,{\rm mK}$ around the null, with a steep
+scaling towards radio frequencies. This is above current raw sensitivity limits
+for many radio facilities at these wavelengths, providing a unique way to
+confirm the cosmological origin of the ARCADE excess and probe its properties
+(e.g., redshift dependence and isotropy). We also give an expression to compute
+the radio-analogue of the kinematic SZ effect, highlighting that this might
+provide a new tool to probe large-scale velocity fields and the cosmic
+evolution of the radio background.",2110.08373v1
+2021-10-20,No Transits of Proxima Centauri Planets in High-Cadence TESS Data,"Proxima Centauri is our nearest stellar neighbor and one of the most
+well-studied stars in the sky. In 2016, a planetary companion was detected
+through radial velocity measurements. Proxima Centauri b has a minimum mass of
+1.3 Earth masses and orbits with a period of 11.2 days at 0.05 AU from its
+stellar host, and resides within the star's Habitable Zone. While recent work
+has shown that Proxima Centauri b likely does not transit, given the value of
+potential atmospheric observations via transmission spectroscopy of the closest
+possible Habitable Zone planet, we reevaluate the possibility that Proxima
+Centauri b is a transiting exoplanet using data from the Transiting Exoplanet
+Survey Satellite (TESS). We use three sectors (Sectors 11, 12, and 38 at
+2-minute cadence) of observations from TESS to search for planets. Proxima
+Centauri is an extremely active M5.5 star, emitting frequent white-light
+flares; we employ a novel method that includes modeling the stellar activity in
+our planet search algorithm. We do not detect any planet signals. We injected
+synthetic transiting planets into the TESS and use this analysis to show that
+Proxima Centauri b cannot be a transiting exoplanet with a radius larger than
+0.4 R$_\oplus$. Moreover, we show that it is unlikely that any Habitable Zone
+planets larger than Mars transit Proxima Centauri.",2110.10702v2
+2021-12-20,Analysis of preintegration followed by quasi-Monte Carlo integration for distribution functions and densities,"In this paper, we analyse a method for approximating the distribution
+function and density of a random variable that depends in a non-trivial way on
+a possibly high number of independent random variables, each with support on
+the whole real line. Starting with the integral formulations of the
+distribution and density, the method involves smoothing the original integrand
+by preintegration with respect to one suitably chosen variable, and then
+applying a suitable quasi-Monte Carlo (QMC) method to compute the integral of
+the resulting smoother function. Interpolation is then used to reconstruct the
+distribution or density on an interval. The preintegration technique is a
+special case of conditional sampling, a method that has previously been applied
+to a wide range of problems in statistics and computational finance. In
+particular, the pointwise approximation studied in this work is a specific case
+of the conditional density estimator previously considered in L'Ecuyer et al.,
+arXiv:1906.04607. Our theory provides a rigorous regularity analysis of the
+preintegrated function, which is then used to show that the errors of the
+pointwise and interpolated estimators can both achieve nearly first-order
+convergence. Numerical results support the theory.",2112.10308v5
+2021-12-21,Exponential decay of intersection volume with applications on list-decodability and Gilbert-Varshamov type bound,"We give some natural sufficient conditions for balls in a metric space to
+have small intersection. Roughly speaking, this happens when the metric space
+is (i) expanding and (ii) well-spread, and (iii) a certain random variable on
+the boundary of a ball has a small tail. As applications, we show that the
+volume of intersection of balls in Hamming, Johnson spaces and symmetric groups
+decay exponentially as their centers drift apart. To verify condition (iii), we
+prove some large deviation inequalities `on a slice' for functions with
+Lipschitz conditions.
+  We then use these estimates on intersection volumes to
+  $\bullet$ obtain a sharp lower bound on list-decodability of random $q$-ary
+codes, confirming a conjecture of Li and Wootters; and
+  $\bullet$ improve the classical bound of Levenshtein from 1971 on constant
+weight codes by a factor linear in dimension, resolving a problem raised by
+Jiang and Vardy.
+  Our probabilistic point of view also offers a unified framework to obtain
+improvements on other Gilbert--Varshamov type bounds, giving conceptually
+simple and calculation-free proofs for $q$-ary codes, permutation codes, and
+spherical codes. Another consequence is a counting result on the number of
+codes, showing ampleness of large codes.",2112.11274v2
+2021-12-22,Preintegration is not smoothing when monotonicity fails,"Preintegration is a technique for high-dimensional integration over
+$d$-dimensional Euclidean space, which is designed to reduce an integral whose
+integrand contains kinks or jumps to a $(d-1)$-dimensional integral of a smooth
+function. The resulting smoothness allows efficient evaluation of the
+$(d-1)$-dimensional integral by a Quasi-Monte Carlo or Sparse Grid method. The
+technique is similar to conditional sampling in statistical contexts, but the
+intention is different: in conditional sampling the aim is to reduce the
+variance, rather than to achieve smoothness. Preintegration involves an initial
+integration with respect to one well chosen real-valued variable. Griebel, Kuo,
+Sloan [Math. Comp. 82 (2013), 383--400] and Griewank, Kuo, Le\""ovey, Sloan [J.
+Comput. Appl. Maths. 344 (2018), 259--274] showed that the resulting
+$(d-1)$-dimensional integrand is indeed smooth under appropriate conditions,
+including a key assumption -- the integrand of the smooth function underlying
+the kink or jump is strictly monotone with respect to the chosen special
+variable when all other variables are held fixed. The question addressed in
+this paper is whether this monotonicity property with respect to one well
+chosen variable is necessary. We show here that the answer is essentially yes,
+in the sense that without this property the resulting $(d-1)$-dimensional
+integrand is generally not smooth, having square-root or other singularities.",2112.11621v1
+2021-12-30,A causal inference framework for spatial confounding,"Recently, addressing spatial confounding has become a major topic in spatial
+statistics. However, the literature has provided conflicting definitions, and
+many proposed definitions do not address the issue of confounding as it is
+understood in causal inference. We define spatial confounding as the existence
+of an unmeasured causal confounder with a spatial structure. We present a
+causal inference framework for nonparametric identification of the causal
+effect of a continuous exposure on an outcome in the presence of spatial
+confounding. We propose double machine learning (DML), a procedure in which
+flexible models are used to regress both the exposure and outcome variables on
+confounders to arrive at a causal estimator with favorable robustness
+properties and convergence rates, and we prove that this approach is consistent
+and asymptotically normal under spatial dependence. As far as we are aware,
+this is the first approach to spatial confounding that does not rely on
+restrictive parametric assumptions (such as linearity, effect homogeneity, or
+Gaussianity) for both identification and estimation. We demonstrate the
+advantages of the DML approach analytically and in simulations. We apply our
+methods and reasoning to a study of the effect of fine particulate matter
+exposure during pregnancy on birthweight in California.",2112.14946v7
+2022-01-20,Accurate modeling of grazing transits using umbrella sampling,"Grazing transits present a special problem for statistical studies of
+exoplanets. Even though grazing planetary orbits are rare (due to geometric
+selection effects), for many low to moderate signal-to-noise cases, a
+significant fraction of the posterior distribution is nonetheless consistent
+with a grazing geometry. A failure to accurately model grazing transits can
+therefore lead to biased inferences even for cases where the planet is not
+actually on a grazing trajectory. With recent advances in stellar
+characterization, the limiting factor for many scientific applications is now
+the quality of available transit fits themselves, and so the time is ripe to
+revisit the transit fitting problem. In this paper, we model exoplanet transits
+using a novel application of umbrella sampling and a geometry-dependent
+parameter basis that minimizes covariances between transit parameters. Our
+technique splits the transit fitting problem into independent Monte Carlo
+sampling runs for the grazing, non-grazing, and transition regions of the
+parameter space, which we then recombine into a single joint posterior
+probability distribution using a robust weighting scheme. Our method can be
+trivially parallelized and so requires no increase in the wall clock time
+needed for computations. Most importantly, our method produces accurate
+estimates of exoplanet properties for both grazing and non-grazing orbits,
+yielding more robust results than standard methods for many common star-planet
+configurations.",2201.08350v1
+2022-04-22,Reward Reports for Reinforcement Learning,"Building systems that are good for society in the face of complex societal
+effects requires a dynamic approach. Recent approaches to machine learning (ML)
+documentation have demonstrated the promise of discursive frameworks for
+deliberation about these complexities. However, these developments have been
+grounded in a static ML paradigm, leaving the role of feedback and
+post-deployment performance unexamined. Meanwhile, recent work in reinforcement
+learning has shown that the effects of feedback and optimization objectives on
+system behavior can be wide-ranging and unpredictable. In this paper we sketch
+a framework for documenting deployed and iteratively updated learning systems,
+which we call Reward Reports. Taking inspiration from various contributions to
+the technical literature on reinforcement learning, we outline Reward Reports
+as living documents that track updates to design choices and assumptions behind
+what a particular automated system is optimizing for. They are intended to
+track dynamic phenomena arising from system deployment, rather than merely
+static properties of models or data. After presenting the elements of a Reward
+Report, we discuss a concrete example: Meta's BlenderBot 3 chatbot. Several
+others for game-playing (DeepMind's MuZero), content recommendation
+(MovieLens), and traffic control (Project Flow) are included in the appendix.",2204.10817v3
+2022-05-29,Generalized Stochastic Matching,"In this paper, we generalize the recently studied Stochastic Matching problem
+to more accurately model a significant medical process, kidney exchange, and
+several other applications. Up until now the Stochastic Matching problem that
+has been studied was as follows: given a graph G = (V, E), each edge is
+included in the realized sub-graph of G mutually independently with probability
+p_e, and the goal is to find a degree-bounded sub-graph Q of G that has an
+expected maximum matching that approximates the expected maximum matching of
+the realized sub-graph. This model does not account for possibilities of vertex
+dropouts, which can be found in several applications, e.g. in kidney exchange
+when donors or patients opt out of the exchange process as well as in online
+freelancing and online dating when online profiles are found to be faked. Thus,
+we will study a more generalized model of Stochastic Matching in which vertices
+and edges are both realized independently with some probabilities p_v, p_e,
+respectively, which more accurately fits important applications than the
+previously studied model.
+  We will discuss the first algorithms and analysis for this generalization of
+the Stochastic Matching model and prove that they achieve good approximation
+ratios. In particular, we show that the approximation factor of a natural
+algorithm for this problem is at least $0.6568$ in unweighted graphs, and $1/2
++ \epsilon$ in weighted graphs for some constant $\epsilon > 0$. We further
+improve our result for unweighted graphs to $2/3$ using edge degree constrained
+subgraphs (EDCS).",2205.14717v1
+2022-07-25,Spin-transfer and spin-orbit torques in the Landau-Lifshitz-Gilbert equation,"Dynamic simulations of spin-transfer and spin-orbit torques are increasingly
+important for a wide range of spintronic devices including magnetic random
+access memory, spin-torque nano-oscillators and electrical switching of
+antiferromagnets. Here we present a computationally efficient method for the
+implementation of spin-transfer and spin-orbit torques within the
+Landau-Lifshitz-Gilbert equation used in micromagnetic and atomistic
+simulations. We consolidate and simplify the varying terminology of different
+kinds of torques into a physical action and physical origin that clearly shows
+the common action of spin torques while separating their different physical
+origins. Our formalism introduces the spin torque as an effective magnetic
+field, greatly simplifying the numerical implementation and aiding the
+interpretation of results. The strength of the effective spin torque field
+unifies the action of the spin torque and subsumes the details of experimental
+effects such as interface resistance and spin Hall angle into a simple
+transferable number between numerical simulations. We present a series of
+numerical tests demonstrating the mechanics of generalised spin torques in a
+range of spintronic devices. This revised approach to modelling spin-torque
+effects in numerical simulations enables faster simulations and a more direct
+way of interpreting the results, and thus it is also suitable to be used in
+direct comparisons with experimental measurements or in a modelling tool that
+takes experimental values as input.",2207.12071v2
+2022-08-03,On ergodic invariant measures for the stochastic Landau-Lifschitz-Gilbert equation in 1D,"We establish existence of an ergodic invariant measure on
+$H^1(D,\mathbb{R}^3)\cap L^2(D,\mathbb{S}^2)$ for the stochastic
+Landau-Lifschitz-Gilbert equation on a bounded one dimensional interval $D$.
+The conclusion is achieved by employing the classical Krylov-Bogoliubov
+theorem. In contrast to other equations, verifying the hypothesis of the
+Krylov-Bogoliubov theorem is not a standard procedure. We employ rough paths
+theory to show that the semigroup associated to the equation has the Feller
+property in $H^1(D,\mathbb{R}^3)\cap L^2(D,\mathbb{S}^2)$. It does not seem
+possible to achieve the same conclusion by the classical Stratonovich calculus.
+On the other hand, we employ the classical Stratonovich calculus to prove the
+tightness hypothesis. The Krein-Milman theorem implies existence of an ergodic
+invariant measure. In case of spatially constant noise, we show that there
+exists a unique Gibbs invariant measure and we establish the qualitative
+behaviour of the unique stationary solution. In absence of the anisotropic
+energy and for a spatially constant noise, we are able to provide a path-wise
+long time behaviour result: in particular, every solution synchronises with a
+spherical Brownian motion and it is recurrent for large times",2208.02136v2
+2023-01-25,"The Benchmark M Dwarf Eclipsing Binary CM Draconis With TESS: Spots, Flares and Ultra-Precise Parameters","A gold standard for the study of M dwarfs is the eclipsing binary CM
+Draconis. It is rare because it is bright ($J_{\rm mag}=8.5$) and contains twin
+fully convective stars on an almost perfectly edge-on orbit. Both masses and
+radii were previously measured to better than $1\%$ precision, amongst the best
+known. We use 15 sectors of data from the Transiting Exoplanet Survey Satellite
+(TESS) to show that CM Draconis is the gift that keeps on giving. Our paper has
+three main components. First, we present updated parameters, with radii and
+masses constrained to previously unheard of precisions of $\approx 0.06\%$ and
+$\approx 0.12\%$, respectively. Second, we discover strong and variable spot
+modulation, suggestive of spot clustering and an activity cycle on the order of
+$\approx 4$ years. Third, we discover 163 flares. We find a relationship
+between the spot modulation and flare rate, with flares more likely to occur
+when the stars appear brighter. This may be due to a positive correlation
+between flares and the occurrence of bright spots (plages). The flare rate is
+surprisingly not reduced during eclipse, but one flare may show evidence of
+being occulted. We suggest the flares may be preferentially polar, which has
+positive implications for the habitability of planets orbiting M dwarfs.",2301.10858v2
+2023-02-23,Beyond Bias and Compliance: Towards Individual Agency and Plurality of Ethics in AI,"AI ethics is an emerging field with multiple, competing narratives about how
+to best solve the problem of building human values into machines. Two major
+approaches are focused on bias and compliance, respectively. But neither of
+these ideas fully encompasses ethics: using moral principles to decide how to
+act in a particular situation. Our method posits that the way data is labeled
+plays an essential role in the way AI behaves, and therefore in the ethics of
+machines themselves. The argument combines a fundamental insight from ethics
+(i.e. that ethics is about values) with our practical experience building and
+scaling machine learning systems. We want to build AI that is actually ethical
+by first addressing foundational concerns: how to build good systems, how to
+define what is good in relation to system architecture, and who should provide
+that definition.
+  Building ethical AI creates a foundation of trust between a company and the
+users of that platform. But this trust is unjustified unless users experience
+the direct value of ethical AI. Until users have real control over how
+algorithms behave, something is missing in current AI solutions. This causes
+massive distrust in AI, and apathy towards AI ethics solutions. The scope of
+this paper is to propose an alternative path that allows for the plurality of
+values and the freedom of individual expression. Both are essential for
+realizing true moral character.",2302.12149v1
+2023-04-03,Three-Dimensional Structure of Hybrid Magnetic Skyrmions Determined by Neutron Scattering,"Magnetic skyrmions are topologically protected chiral spin textures which
+present opportunities for next-generation magnetic data storage and logic
+information technologies. The topology of these structures originates in the
+geometric configuration of the magnetic spins - more generally described as the
+structure. While the skyrmion structure is most often depicted using a 2D
+projection of the three-dimensional structure, recent works have emphasized the
+role of all three dimensions in determining the topology and their response to
+external stimuli. In this work, grazing-incidence small-angle neutron
+scattering and polarized neutron reflectometry are used to determine the
+three-dimensional structure of hybrid skyrmions. The structure of the hybrid
+skyrmions, which includes a combination of N\'eel-like and Bloch-like
+components along their length, is expected to significantly contribute to their
+notable stability, which includes ambient conditions. To interpret the neutron
+scattering data, micromagnetic simulations of the hybrid skyrmions were
+performed, and the corresponding diffraction patterns were determined using a
+Born approximation transformation. The converged magnetic profile reveals the
+magnetic structure along with the skyrmion depth profile, including the
+thickness of the Bloch and N\'eel segments and the diameter of the core.",2304.01369v2
+2023-05-18,Towards Intersectional Moderation: An Alternative Model of Moderation Built on Care and Power,"Shortcomings of current models of moderation have driven policy makers,
+scholars, and technologists to speculate about alternative models of content
+moderation. While alternative models provide hope for the future of online
+spaces, they can fail without proper scaffolding. Community moderators are
+routinely confronted with similar issues and have therefore found creative ways
+to navigate these challenges. Learning more about the decisions these
+moderators make, the challenges they face, and where they are successful can
+provide valuable insight into how to ensure alternative moderation models are
+successful.
+  In this study, I perform a collaborative ethnography with moderators of
+r/AskHistorians, a community that uses an alternative moderation model,
+highlighting the importance of accounting for power in moderation. Drawing from
+Black feminist theory, I call this ""intersectional moderation."" I focus on
+three controversies emblematic of r/AskHistorians' alternative model of
+moderation: a disagreement over a moderation decision; a collaboration to fight
+racism on Reddit; and a period of intense turmoil and its impact on policy.
+Through this evidence I show how volunteer moderators navigated multiple layers
+of power through care work. To ensure the successful implementation of
+intersectional moderation, I argue that designers should support
+decision-making processes and policy makers should account for the impact of
+the sociotechnical systems in which moderators work.",2305.11250v1
+2023-06-08,Environmental Considerations in the age of Space Exploration: the Conservation and Protection of Non-Earth Environments,"This document is an abbreviated version of the law review, led by Alexander
+Q. Gilbert, entitled: ""Major Federal Actions Significantly Affecting the
+Quality of the Space Environment: Applying NEPA to Federal and Federally
+Authorized Outer Space Activities."" Here, we discuss the future of the space
+environment, and how it is increasingly becoming a human environment with
+regard to continued robotic and human presence in orbit, planned and proposed
+robotic and human presence on bodies such as the Moon and Mars, planned space
+mining projects, the increase use of low-Earth orbit for communications
+satellites, and other human uses of space. As such, we must evaluate and
+protect these environments just as we do on Earth. In order to prioritize
+mitigating threat of contamination, avoiding conflict, and promoting
+sustainability in space, all to ensure that actors maintain equal and safe
+access to space, we propose applying the National Environmental Policy Act, or
+NEPA, to space missions. We put forward three examples of environmental best
+practices for those involved in space missions to consider: adopting
+precautionary and communicative structure to before, during, and after missions
+taking place off-world, environmental impact statements, and transparency in
+tools that may impact the environment (including radioisotope power sources,
+plans in case of vehicle loss or loss of trajectory, and others). For
+additional discussion related to potential space applications of NEPA, NEPA's
+statutory text, and NEPA's relation to space law and judicial precedent for
+space, we recommend reading the full law review.",2306.05594v1
+2023-07-13,Accurate and efficient photo-eccentric transit modeling,"A planet's orbital eccentricity is fundamental to understanding the present
+dynamical state of a system and is a relic of its formation history. There is
+high scientific value in measuring eccentricities of Kepler and TESS planets
+given the sheer size of these samples and the diversity of their planetary
+systems. However, Kepler and TESS lightcurves typically only permit robust
+determinations of planet-to-star radius ratio $r$, orbital period $P$, and
+transit mid-point $t_0$. Three other orbital properties, including impact
+parameter $b$, eccentricity $e$, and argument of periastron $\omega$, are more
+challenging to measure because they are all encoded in the lightcurve through
+subtle effects on a single observable -- the transit duration $T_{14}$. In
+Gilbert, MacDougall, & Petigura (2022), we showed that a five-parameter transit
+description $\{P, t_0, r, b, T_{14}\}$ naturally yields unbiased measurements
+of $r$ and $b$. Here, we build upon our previous work and introduce an accurate
+and efficient prescription to measure $e$ and $\omega$. We validate this
+approach through a suite of injection-and-recovery experiments. Our method
+agrees with previous approaches that use a seven-parameter transit description
+$\{P, t_0, r, b, \rho_\star, e, \omega\}$ which explicitly fits the
+eccentricity vector and mean stellar density. The five-parameter method is
+simpler than the seven-parameter method and is ""future-proof"" in that posterior
+samples can be quickly reweighted (via importance sampling) to accommodate
+updated priors and updated stellar properties. This method thus circumvents the
+need for an expensive reanalysis of the raw photometry, offering a streamlined
+path toward large-scale population analyses of eccentricity from transit
+surveys.",2307.07070v1
+2023-09-01,"A decoupled, convergent and fully linear algorithm for the Landau--Lifshitz--Gilbert equation with magnetoelastic effects","We consider the coupled system of the Landau--Lifshitz--Gilbert equation and
+the conservation of linear momentum law to describe magnetic processes in
+ferromagnetic materials including magnetoelastic effects in the small-strain
+regime. For this nonlinear system of time-dependent partial differential
+equations, we present a decoupled integrator based on first-order finite
+elements in space and an implicit one-step method in time. We prove
+unconditional convergence of the sequence of discrete approximations towards a
+weak solution of the system as the mesh size and the time-step size go to zero.
+Compared to previous numerical works on this problem, for our method, we prove
+a discrete energy law that mimics that of the continuous problem and, passing
+to the limit, yields an energy inequality satisfied by weak solutions.
+Moreover, our method does not employ a nodal projection to impose the unit
+length constraint on the discrete magnetisation, so that the stability of the
+method does not require weakly acute meshes. Furthermore, our integrator and
+its analysis hold for a more general setting, including body forces and
+traction, as well as a more general representation of the magnetostrain.
+Numerical experiments underpin the theory and showcase the applicability of the
+scheme for the simulation of the dynamical processes involving magnetoelastic
+materials at submicrometer length scales.",2309.00605v2
+2023-11-09,Skyrmion-Excited Spin Wave Fractal Network,"Magnetic skyrmions exhibit unique, technologically relevant pseudo-particle
+behaviors which arise from their topological protection, including
+well-defined, three-dimensional dynamic modes that occur at microwave
+frequencies. During dynamic excitation, spin waves are ejected into the
+interstitial regions between skyrmions, creating the magnetic equivalent of a
+turbulent sea. However, since the spin waves in these systems have a
+well-defined length scale, and the skyrmions are on an ordered lattice, ordered
+structures from spin wave interference can precipitate from the chaos. This
+work uses small angle neutron scattering (SANS) to capture the dynamics in
+hybrid skyrmions and investigate the spin wave structure. Performing
+simultaneous ferromagnetic resonance and SANS, the diffraction pattern shows a
+large increase in low-angle scattering intensity which is present only in the
+resonance condition. This scattering pattern is best fit using a mass fractal
+model, which suggests the spin waves form a long-range fractal network. The
+fractal structure is constructed of fundamental units with a size that encodes
+the spin wave emissions and are constrained by the skyrmion lattice. These
+results offer critical insights into the nanoscale dynamics of skyrmions,
+identify a new dynamic spin wave fractal structure, and demonstrates SANS as a
+unique tool to probe high-speed dynamics.",2311.05469v1
+2023-12-08,Analysis of the magnetization control problem for the 2D evolutionary Landau-Lifshitz-Gilbert equation,"The magnetization control problem for the Landau-Lifshitz-Gilbert (LLG)
+equation $m_t= m \times (\Delta m +u)- m \times (m \times (\Delta m +u)),\
+(x,t) \in \Omega\times (0,T] $ with zero Neumann boundary data on a
+two-dimensional bounded domain $\Omega$ is studied when the control energy $u$
+is applied on the effective field. First, we show the existence of a weak
+solution, and the magnetization vector field $m$ satisfies an energy
+inequality. If a weak solution $m$ obeys the condition that $\nabla m\in
+L^4(0,T;L^4(\Omega)),$ then we show that it is a regular solution. The
+classical cost functional is modified by incorporating
+$L^4(0,T;L^4(\Omega))$-norm of $\nabla m$ so that a rigorous study of the
+optimal control problem is established. Then, we justified the existence of an
+optimal control and derived first-order necessary optimality conditions using
+an adjoint problem approach. We have established the continuous dependency and
+Fr\'echet differentiability of the control-to-state and control-to-costate
+operators and shown the Lipschitz continuity of their Fr\'echet derivatives.
+Using these postulates, we derived a local second-order sufficient optimality
+condition when a control belongs to a critical cone. Finally, we also obtain
+another remarkable global optimality condition posed only in terms of the
+adjoint state associated with the control problem.",2312.05165v1
+2024-01-05,Solutions to the Landau-Lifshitz-Gilbert equation in the frequency space: Discretization schemes for the dynamic-matrix approach,"The dynamic matrix method addresses the Landau-Lifshitz-Gilbert (LLG)
+equation in the frequency domain by transforming it into an eigenproblem.
+Subsequent numerical solutions are derived from the eigenvalues and
+eigenvectors of the dynamic matrix. In this work we explore discretization
+methods needed to obtain a matrix representation of the dynamic operator, a
+fundamental counterpart of the dynamic matrix. Our approach opens a new set of
+linear algebra tools for the dynamic matrix method and expose the
+approximations and limitations intrinsic to it. Moreover, our discretization
+algorithms can be applied to various discretization schemes, extending beyond
+micromagnetism problems. We present some application examples, including a
+technique to obtain the dynamic matrix directly from the magnetic free energy
+function of an ensemble of macrospins, and an algorithmic method to calculate
+numerical micromagnetic kernels, including plane wave kernels. We also show how
+to exploit symmetries and reduce the numerical size of micromagnetic
+dynamic-matrix problems by a change of basis. This procedure significantly
+reduces the size of the dynamic matrix by several orders of magnitude while
+maintaining high numerical precision. Additionally, we calculate analytical
+approximations for the dispersion relations in magnonic crystals. This work
+contributes to the understanding of the current magnetization dynamics methods,
+and could help the development and formulations of novel analytical and
+numerical methods for solving the LLG equation within the frequency domain.",2401.02933v2
+2015-04-16,Formulas for the Walsh coefficients of smooth functions and their application to bounds on the Walsh coefficients,"We establish formulas for the $b$-adic Walsh coefficients of functions in
+$C^\alpha[0,1]$ for an integer $\alpha \geq 1$ and give upper bounds on the
+Walsh coefficients of these functions. We also study the Walsh coefficients of
+periodic and non-periodic functions in reproducing kernel Hilbert spaces.",1504.04131v2
+2017-07-10,Taylor coefficients of non-holomorphic Jacobi forms and applications,"In this paper, we prove modularity results of Taylor coefficients of certain
+non-holomorphic Jacobi forms. It is well-known that Taylor coefficients of
+holomorphic Jacobi forms are quasimoular forms. However recently there has been
+a wide interest for Taylor coefficients of non-holomorphic Jacobi forms for
+example arising in combinatorics. In this paper, we show that such coefficients
+still inherit modular properties. We then work out the precise spaces in which
+these coefficients lie for two examples.",1707.02703v1
+2022-02-14,Coefficient Decomposition of Spatial Regressive Models Based on Standardized Variables,"Spatial autocorrelation analysis is the basis for spatial autoregressive
+modeling. However, the relationships between spatial correlation coefficients
+and spatial regression models are not yet well clarified. The paper is devoted
+to explore the deep structure of spatial regression coefficients. By means of
+mathematical reasoning, a pair of formulae of canonical spatial regression
+coefficients are derived from a general spatial regression model based on
+standardized variables. The spatial auto- and lag-regression coefficients are
+reduced to a series of statistic parameters and measurements, including
+conventional regressive coefficient, Pearson correlation coefficient, Moran's
+indexes, spatial cross-correlation coefficients, and the variance of prediction
+residuals. The formulae show determinate inherent relationships between spatial
+correlation coefficients and spatial regression coefficients. New finding is as
+below: the spatial autoregressive coefficient mainly depends on the Moran's
+index of the independent variable, while the spatial lag-regressive coefficient
+chiefly depends on the cross-correlation coefficient of independent variable
+and dependent variable. The observational data of an urban system in Beijing,
+Tianjin, and Hebei region of China were employed to verify the newly derived
+formulae, and the results are satisfying. The new formulae and their variates
+are helpful for understand spatial regression models from the perspective of
+spatial correlation and can be used to assist spatial regression modeling.",2202.06535v1
+2023-05-12,VC-PINN: Variable Coefficient Physical Information Neural Network For Forward And Inverse PDE Problems with Variable Coefficient,"The paper proposes a deep learning method specifically dealing with the
+forward and inverse problem of variable coefficient partial differential
+equations -- Variable Coefficient Physical Information Neural Network
+(VC-PINN). The shortcut connections (ResNet structure) introduced into the
+network alleviates the ""Vanishing gradient"" and unifies the linear and
+nonlinear coefficients. The developed method was applied to four equations
+including the variable coefficient Sine-Gordon (vSG), the generalized variable
+coefficient Kadomtsev-Petviashvili equation (gvKP), the variable coefficient
+Korteweg-de Vries equation (vKdV), the variable coefficient Sawada-Kotera
+equation (vSK). Numerical results show that VC-PINN is successful in the case
+of high dimensionality, various variable coefficients (polynomials,
+trigonometric functions, fractions, oscillation attenuation coefficients), and
+the coexistence of multiple variable coefficients. We also conducted an
+in-depth analysis of VC-PINN in a combination of theory and numerical
+experiments, including four aspects, the necessity of ResNet, the relationship
+between the convexity of variable coefficients and learning, anti-noise
+analysis, the unity of forward and inverse problems/relationship with standard
+PINN.",2305.07479v2
+1995-10-27,Radiation Damping and Quantum Excitation for Longitudinal Charged Particle Dynamics in the Thermal Wave Model,"On the basis of the recently proposed {\it Thermal Wave Model (TWM) for
+particle beams}, we give a description of the longitudinal charge particle
+dynamics in circular accelerating machines by taking into account both
+radiation damping and quantum excitation (stochastic effect), in presence of a
+RF potential well. The longitudinal dynamics is governed by a 1-D
+Schr\""{o}dinger-like equation for a complex wave function whose squared modulus
+gives the longitudinal bunch density profile. In this framework, the
+appropriate {\it r.m.s. emittance} scaling law, due to the damping effect, is
+naturally recovered, and the asymptotic equilibrium condition for the bunch
+length, due to the competition between quantum excitation (QE) and radiation
+damping (RD), is found. This result opens the possibility to apply the TWM,
+already tested for protons, to electrons, for which QE and RD are very
+important.",9510004v1
+1994-02-04,Constraints on Models of Galaxy Formation from the Evolution of Damped Ly$α$ Absorption Systems,"There is accumulating observational evidence suggesting that damped
+Ly$\alpha$ absorption systems systems are the progenitors of present-day spiral
+galaxies. We use the observed properties of these systems to place constraints
+on the history of star formation in galactic disks, and on cosmological
+theories of structure formation in the universe. We show that the observed
+increase in $\Omega_{HI}$ contributed by damped Ly$\alpha$ systems at high
+redshift implies that star formation must have been considerably less efficient
+in the past. We also show that the data can constrain cosmological models in
+which structure forms at late epochs. A mixed dark matter (MDM) model with
+$\Omega_{\nu}=0.3$ is unable to reproduce the mass densities of cold gas seen
+at high redshift, even in the absence of any star formation. We show that at
+redshifts greater than 3, this model predicts that the total baryonic mass
+contained in dark matter halos with circular velocities $V_c > 35$ km s$^{-1}$
+is less than the observed mass of HI in damped systems. At these redshifts, the
+photo-ionizing background would prevent gas from dissipating and collapsing to
+form high column density systems in halos smaller than 35 km s$^{-1}$. MDM
+models are thus ruled out by the observations.",9402015v1
+1999-02-11,The HI Column Density Distribution Function at z=0: the Connection to Damped Ly alpha Statistics,"We present a measurement of the HI column density distribution function,
+f(N), at the present epoch for column densities log N > 20 cm^-2. These high
+column densities compare to those measured in damped Ly alpha lines seen in
+absorption against background quasars. Although observationally rare, it
+appears that the bulk of the neutral gas in the Universe is associated with
+these damped Ly alpha systems. In order to obtain a good anchor point at z=0 we
+determine f(N) in the local Universe by using 21cm synthesis observations of a
+complete sample of spiral galaxies. We show that f(N) for damped Ly alpha
+systems has changed significantly from high z to the present and that change is
+greatest for the highest column densities. The measurements indicate that low
+surface brightness galaxies make a minor contribution to the cross section for
+HI, especially for log N > 21^-2.",9902171v1
+2000-10-27,Planetary Torques as the Viscosity of Protoplanetary Disks,"We revisit the idea that density-wave wakes of planets drive accretion in
+protostellar disks. The effects of many small planets can be represented as a
+viscosity if the wakes damp locally, but the viscosity is proportional to the
+damping length. Damping occurs mainly by shocks even for earth-mass planets.
+The excitation of the wake follows from standard linear theory including the
+torque cutoff. We use this as input to an approximate but quantitative
+nonlinear theory based on Burger's equation for the subsequent propagation and
+shock. Shock damping is indeed local but weakly so. If all metals in a
+minimum-mass solar nebula are invested in planets of a few earth masses each,
+dimensionless viscosities [alpha] of order dex(-4) to dex(-3) result. We
+compare this with observational constraints. Such small planets would have
+escaped detection in radial-velocity surveys and could be ubiquitous. If so,
+then the similarity of the observed lifetime of T Tauri disks to the
+theoretical timescale for assembling a rocky planet may be fate rather than
+coincidence.",0010576v1
+2000-12-27,Constraining Dark Matter candidates from structure formation,"We show that collisional damping of adiabatic primordial fluctuations yields
+constraints on the possible range of mass and interaction rates of Dark Matter
+particles. Our analysis relies on a general classification of Dark Matter
+candidates, that we establish independently of any specific particle theory or
+model. From a relation between the collisional damping scale and the Dark
+Matter interaction rate, we find that Dark Matter candidates must have
+cross-sections at decoupling smaller than $ 10^{-33} \frac{m_{dm}}{1 MeV} cm^2$
+with photons and $10^{-37} \frac{m_{dm}}{1 MeV} cm^2$ with neutrinos, to
+explain the observed primordial structures of $10^9$ Solar mass. These damping
+constraints are particularly relevant for Warm Dark Matter candidates. They
+also leave open less known regions of parameter space corresponding to
+particles having rather high interaction rates with other species than
+neutrinos and photons.",0012504v2
+2001-07-26,The Contribution of HI-Rich Galaxies to the Damped Absorber Population at z=0,"We present a study of HI-rich galaxies in the local universe selected from
+blind emission-line surveys. These galaxies represent the emission-line
+counterparts of local damped Lyman-alpha systems. We find that the HI
+cross-section of galaxies is drawn from a large range of galaxy masses below
+M_star, 66% of the area comes from galaxies in the range 8.5 < Log M_star <
+9.7. Both because of the low mass galaxy contribution, and because of the range
+of galaxy types and luminosities at any given HI mass, the galaxies
+contributing to the HI cross-section are not exclusively L_star spirals, as is
+often expected. The optical and near infrared counterparts of these galaxies
+cover a range of types (from spirals to irregulars), luminosities (from L_star
+to <0.01 L_star), and surface brightnesses. The range of optical and near
+infrared properties as well as the kinematics for this population are
+consistent with the properties for the low-z damped Lyman-alpha absorbers. We
+also show that the number of HI-rich galaxies in the local universe does not
+preclude evolution of the low-z damped absorber population, but it is
+consistent with no evolution.",0107495v1
+2003-11-17,Wave damping by MHD turbulence and its effect upon cosmic ray propagation in the ISM,"Cosmic rays scatter off magnetic irregularities (Alfven waves) with which
+they are resonant, that is waves of wavelength comparable to their gyroradii.
+These waves may be generated either by the cosmic rays themselves, if they
+stream faster than the Alfven speed, or by sources of MHD turbulence. Waves
+excited by streaming cosmic rays are ideally shaped for scattering, whereas the
+scattering efficiency of MHD turbulence is severely diminished by its
+anisotropy. We show that MHD turbulence has an indirect effect on cosmic ray
+propagation by acting as a damping mechanism for cosmic ray generated waves.
+The hot (``coronal'') phase of the interstellar medium is the best candidate
+location for cosmic ray confinement by scattering from self-generated waves. We
+relate the streaming velocity of cosmic rays to the rate of turbulent
+dissipation in this medium, for the case in which turbulent damping is the
+dominant damping mechanism. We conclude that cosmic rays with up to 10^2 GeV
+could not stream much faster than the Alfven speed, but that 10^6 GeV cosmic
+rays would stream unimpeded by self-generated waves unless the coronal gas were
+remarkably turbulence-free.",0311400v1
+2004-10-25,Constraints on Dark Matter interactions from structure formation: Damping lengths,"(Shortened) Weakly Interacting Massive Particles are often said to be the
+best Dark Matter candidates. Studies have shown however that rather large Dark
+Matter-photon or Dark Matter-baryon interactions could be allowed by cosmology.
+Here we address the question of the role of the Dark Matter interactions in
+more detail to determine at which extent Dark Matter has to be necessarily
+weakly interacting. To this purpose, we compute the collisional damping (and
+free-streaming) lengths of generic interacting Dark Matter candidates and
+compare them to the scale of the smallest primordial structures known to exist
+in the Universe. We obtain necessary conditions that any candidate must
+satisfy. We point out the existence of new Dark Matter scenarios and exhibit
+new damping regimes. For example, an interacting candidate may bear a similar
+damping than that of collisionless Warm Dark Matter particles. The main
+difference is due to the Dark Matter coupling to interacting (or even
+freely-propagating) species. Our approach yields a general classification of
+Dark Matter candidates which extends the definitions of the usual Cold, Warm
+and Hot Dark Matter scenarios when interactions, weak or strong, are
+considered.",0410591v1
+2005-10-10,Collisional dissipation of Alfvén waves in a partially ionised solar chromosphere,"Certain regions of the solar atmosphere are at sufficiently low temperatures
+to be only partially ionised. The lower chromosphere contains neutral atoms,
+the existence of which greatly increases the efficiency of the damping of waves
+due to collisional friction momentum transfer. More specifically the Cowling
+conductivity can be up to 12 orders of magnitude smaller than the Spitzer
+value, so that the main damping mechanism in this region is due to the
+collisions between neutrals and positive ions. Using values for the gas density
+and temperature as functions of height taken from the VAL C model of the quiet
+Sun, an estimate is made for the dependance of the Cowling conductivity on
+height and strength of magnetic field. Using both analytic and numerical
+approaches the passage of Alfven waves over a wide spectrum through this
+partially ionised region is investigated. Estimates of the efficiency of this
+region in the damping of Alfven waves are made and compared for both
+approaches. We find that Alfven waves with frequencies above 0.6Hz are
+completely damped and frequencies below 0.01 Hz unaffected.",0510265v1
+2006-04-10,The Nearby Damped Lyman-alpha Absorber SBS 1543+593: A Large HI Envelope in a Gas-Rich Galaxy Group,"We present a Very Large Array (VLA) HI 21cm map and optical observations of
+the region around one of the nearest damped Lyman-alpha absorbers beyond the
+local group, SBS 1543+593. Two previously uncataloged galaxies have been
+discovered and a redshift has been determined for a third. All three of these
+galaxies are at the redshift of SBS 1543+593 and are ~185 kpc from the damped
+Lyman-alpha absorber. We discuss the HI and optical properties of SBS 1543+593
+and its newly identified neighbors. Both SBS 1543+593 and Dwarf 1 have baryonic
+components that are dominated by neutral gas -- unusual for damped Lyman-alpha
+absorbers for which only ~5% of the HI cross-section originates in such
+strongly gas-dominated systems. What remains unknown is whether low mass
+gas-rich groups are common surrounding gas-rich galaxies in the local universe
+and whether the low star-formation rate in these systems is indicative of a
+young system or a stable, slowly evolving system. We discuss these evolutionary
+scenarios and future prospects for answering these questions.",0604220v1
+2006-08-02,SINS of Viscosity Damped Turbulence,"The problems with explaining the Small Ionized and Neutral Structures (SINS)
+appealing to turbulence stem from inefficiency of the Kolmogorov cascade in
+creating large fluctuations at sufficiently small scales. However, other types
+of cascades are possible. When magnetic turbulence in a fluid with viscosity
+that is much larger than resistivity gets to a viscous damping scale, the
+turbulence does not vanish. Instead, it gets into a different new regime.
+Viscosity-damped turbulence produces fluctuations on the small scales. Magnetic
+fields sheared by turbulent motions by eddies not damped by turbulence create
+small scale filaments that are confined by the external plasma pressure. This
+creates small scale density fluctuations. In addition, extended current sheets
+create even stronger density gradients that accompany field reversals in the
+plane perpendicular to mean magnetic field. Those can be responsible for the
+SINS formation. This scenario is applicable to partially ionized gas. More
+studies of reconnection in the viscosity dominated regime are necessary to
+understand better the extend to which the magnetic reversals can compress the
+gas.",0608046v3
+1998-01-13,Comparative Study of the Adiabatic Evolution of a Nonlinear Damped Oscillator and an Hamiltonian Generalized Nonlinear Oscillator,"In this paper we study to what extent the canonical equivalence and the
+identity of the geometric phases of dissipative and conservative linear
+oscillators, established in a preceeding paper, can be generalized to nonlinear
+ones. Considering first the 1-D quartic generalized oscillator we determine, by
+means of a perturbative time dependent technic of reduction to normal forms,
+the canonical transformations which lead to the adiabatic invariant of the
+system and to the first order non linear correction to its Hannay angle. Then,
+applying the same transformations to the 1-D quartic damped oscillator we show
+that this oscillator is canonically equivalent to the linear generalized
+harmonic oscillator for finite values of the damping parameter (which implies
+no correction to the linear Hannay angle) whereas, in an appropriate weak
+damping limit, it becomes equivalent to the quartic generalized oscillator
+(which implies a non linear correction to this angle) .",9801017v1
+1995-03-20,Quasiparticle damping in two-dimensional superconductors with unconventional pairing.,"We calculate the damping of excitations due to four-fermionic interaction in
+the case of two-dimensional superconductor with nodes in the spectrum. At zero
+temperature and low frequencies it reveals gapless $\omega^3$ behavior at the
+nodal points. With the frequency increasing the crossover to the normal-state
+regimes appears. At high frequencies the damping strongly depends on details of
+a normal-state spectrum parametrization. Two important particular cases such as
+the models of almost free and tight-binding electrons are studied explicitly
+and the characteristic scales are expressed through the model-free parameters
+of the spectrum at the nodal points. The possibility of crossover in
+temperature dependence of damping in the superconducting phase is discussed.",9503112v1
+1997-10-14,Damping of Hydrodynamic Modes in a Trapped Bose Gas above the Bose-Einstein Transition Temperature,"We calculate the damping of low-lying collective modes of a trapped Bose gas
+in the hydrodynamic regime, and show that this comes solely from the shear
+viscosity, since the contributions from bulk viscosity and thermal conduction
+vanish. The hydrodynamic expression for the damping diverges due to the failure
+of hydrodynamics in the outer parts of the cloud, and we take this into account
+by a physically motivated cutoff procedure. Our analysis of available
+experimental data indicates that higher densities than have yet been achieved
+are necessary for investigating hydrodynamic modes above the Bose-Einstein
+transition temperature.",9710130v2
+1997-12-24,Thermal dephasing and the echo effect in a confined Bose-Einstein condensate,"It is shown that thermal fluctuations of the normal component induce
+dephasing -- reversible damping of the low energy collective modes of a
+confined Bose-Einstein condensate. The dephasing rate is calculated for the
+isotropic oscillator trap, where Landau damping is expected to be suppressed.
+This rate is characterized by a steep temperature dependence, and it is weakly
+amplitude dependent.
+  In the limit of large numbers of bosons forming the condensate, the rate
+approaches zero. However, for the numbers employed by the JILA group, the
+calculated value of the rate is close to the experimental one. We suggest that
+a reversible nature of the damping caused by the thermal dephasing in the
+isotropic trap can be tested by the echo effect. A reversible nature of Landau
+damping is also discussed, and a possibility of observing the echo effect in an
+anisotropic trap is considered as well. The parameters of the echo are
+calculated in the weak echo limit for the isotropic trap. Results of the
+numerical simulations of the echo are also presented.",9712287v1
+1998-09-29,Numerical test of the damping time of layer-by-layer growth on stochastic models,"We perform Monte Carlo simulations on stochastic models such as the
+Wolf-Villain (WV) model and the Family model in a modified version to measure
+mean separation $\ell$ between islands in submonolayer regime and damping time
+$\tilde t$ of layer-by-layer growth oscillations on one dimension. The
+stochastic models are modified, allowing diffusion within interval $r$ upon
+deposited. It is found numerically that the mean separation and the damping
+time depend on the diffusion interval $r$, leading to that the damping time is
+related to the mean separation as ${\tilde t} \sim \ell^{4/3}$ for the WV model
+and ${\tilde t} \sim \ell^2$ for the Family model. The numerical results are in
+excellent agreement with recent theoretical predictions.",9809382v1
+2000-01-10,Enhanced vortex damping by eddy currents in superconductor-semiconduc tor hybrids,"An enhancement of vortex-motion damping in thin Pb/In superconducting films
+is obtained through coupling to an adjacent two-dimensional electron gas formed
+in a modulation-doped GaAs/AlGaAs heterostructure. This effect is observed by
+monitoring the power dissipation at the superconductor in the vortex state
+while increasing the density of the electron gas using a gate voltage.
+Quantitative agreement is found with calculations based on a viscous model of
+vortex damping which considers generation of eddy currents in the electron gas
+by moving flux lines. In the regime of filamentary and channel vortex flow,
+eddy-current damping leads to striking dissipation breakdown due to stopping of
+entire vortex channels.",0001123v1
+2000-10-11,The experimental observation of Beliaev damping in a Bose condensed gas,"We report the first experimental observation of Beliaev damping of a
+collective excitation in a Bose-condensed gas. Beliaev damping is not predicted
+by the Gross-Pitaevskii equation and so this is one of the few experiments that
+tests BEC theory beyond the mean field approximation. Measurements of the
+amplitude of a high frequency scissors mode, show that the Beliaev process
+transfers energy to a lower lying mode and then back and forth between these
+modes. These characteristics are quite distinct from those of Landau damping,
+which leads to a monotonic decrease in amplitude. To enhance the Beliaev
+process we adjusted the geometry of the magnetic trapping potential to give a
+frequency ratio of 2 to 1 between two of the scissors modes of the condensate.
+The ratios of the trap oscillation frequencies $\omega_y / \omega_x$ and
+$\omega_z / \omega_x$ were changed independently, so that we could investigate
+the resonant coupling over a range of conditions.",0010157v1
+2001-06-18,AC induced damping of a fluxon in long Josephson junction,"We present a theoretical and experimental study of Josephson vortex (fluxon)
+moving in the presence of spatially homogeneous dc and ac bias currents. By
+mapping this problem to the problem of calculating the current-voltage
+characteristic of a small Josephson junction, we derive the dependence of the
+average fluxon velocity on the dc bias current. In particular we find that the
+low frequency ac bias current results in an additional nonlinear damping of
+fluxon motion. Such ac induced damping crucially depends on the intrinsic
+damping parameter and increases drastically as this parameter is reduced. We
+find a good agreement of the analysis with both the direct numerical
+simulations and the experimentally measured current-voltage characteristics of
+a long annular Josephson junction with one trapped fluxon.",0106337v1
+2002-03-20,Microscopic nonequilibrium dynamics of an inhomogeneous Bose gas beyond the Born approximation,"Using the prescription of the nonequilibrium statistical operator method, we
+derive a non-Markovian generalization to the kinetic theory described by Walser
+{\sl et al.} [Phys. Rev. A {\bf 59}, 3878 (1999)]. Quasi-particle damping and
+effects arising from the finite duration of a collision are introduced to
+include terms beyond the Born approximation. Such a self-consistent theory is
+shown to conserve energy to second order in the interaction strength, even in
+the Markov limit. This kinetic theory is applied to a simple model of a Bose
+gas confined in a spherical trap to study the full real-time evolution towards
+equilibrium. A modified form for the damping function, is seen to strongly
+improve the energy conservation. Based on a linear response calculation, we
+predict the damping rates and frequencies of the collective excitations. We
+demonstrate the emergence of differing time scales for damping and
+equilibration.",0203415v1
+2003-05-12,Landau damping in trapped Bose-condensed gases,"We study Landau damping in dilute Bose-Einstein condensed gases in both
+spherical and prolate ellipsoidal harmonic traps. We solve the Bogoliubov
+equations for the mode spectrum in both of these cases, and calculate the
+damping by summing over transitions between excited quasiparticle states. The
+results for the spherical case are compared to those obtained in the
+Hartree-Fock approximation, where the excitations take on a single-particle
+character, and excellent agreement between the two approaches is found. We have
+also taken the semiclassical limit of the Hartree-Fock approximation and obtain
+a novel expression for the Landau damping rate involving the time dependent
+self-diffusion function of the thermal cloud. As a final approach, we study the
+decay of a condensate mode by making use of dynamical simulations in which both
+the condensate and thermal cloud are evolved explicitly as a function of time.
+A detailed comparison of all these methods over a wide range of sample sizes
+and trap geometries is presented.",0305251v1
+2003-05-27,Damped finite-time-singularity driven by noise,"We consider the combined influence of linear damping and noise on a dynamical
+finite-time-singularity model for a single degree of freedom. We find that the
+noise effectively resolves the finite-time-singularity and replaces it by a
+first-passage-time or absorbing state distribution with a peak at the
+singularity and a long time tail. The damping introduces a characteristic
+cross-over time. In the early time regime the probability distribution and
+first-passage-time distribution show a power law behavior with scaling exponent
+depending on the ratio of the non linear coupling strength to the noise
+strength. In the late time regime the behavior is controlled by the damping.
+The study might be of relevance in the context of hydrodynamics on a nanometer
+scale, in material physics, and in biophysics.",0305630v1
+2003-06-05,On Surface Plasmon Damping in Metallic Nanoparticles,"Two possible mechanisms of surface plasmon (SP) oscillations damping in
+metallic nanoparticles (MNPs), not connected with electron-phonon interaction
+are investigated theoretically: a) the radiation damping of SP, b) resonant
+coupling of SP oscillations with electronic transitions in matrix. It is shown
+that the radiation damping rate is proportional to the number of electrons in
+MNP and therefore this channel of energy outflow from MNP becomes essential for
+relatively large particles. The investigation of second mechanism shows that
+the rate of SP oscillations energy leakage from MNP dos not depend on particle
+size and is fully determined by the optical characteristics of the matrix. It
+is demonstrated that for very small MNPs of 3-5 nm size, where the strong 3D
+size quantization effect suppresses the electron-phonon interaction, the
+resonance coupling in certain cases provides an effective energy outflow.",0306123v1
+2003-11-13,Damping of Bogoliubov Excitations in Optical Lattices,"Extending recent work to finite temperatures, we calculate the Landau damping
+of a Bogoliubov excitation in an optical lattice, due to coupling to a thermal
+cloud of such excitations. For simplicity, we consider a 1D Bose-Hubbard model
+and restrict ourselves to the first energy band. For energy conservation to be
+satisfied, the excitations in the collision processes must exhibit ``anomalous
+dispersion'', analogous to phonons in superfluid $^4\rm{He}$. This leads to the
+disappearance of all damping processes when $U n^{\rm c 0}\ge 6t$, where $U$ is
+the on-site interaction, $t$ is the hopping matrix element and $n^{\rm c 0}(T)$
+is the number of condensate atoms at a lattice site. This phenomenon also
+occurs in 2D and 3D optical lattices. The disappearance of Beliaev damping
+above a threshold wavevector is noted.",0311321v1
+2004-09-22,Symmetry breaking in driven and strongly damped pendulum,"We examine the conditions for appearance of symmetry breaking bifurcation in
+damped and periodically driven pendulum in the case of strong damping. We show
+that symmetry breaking, unlike other nonlinear phenomena, can exist at high
+dissipation. We prove that symmetry breaking phases exist between phases of
+symmetric normal and symmetric inverted oscillations. We find that symmetry
+broken solutions occupy a sufficiently smaller region of pendulum's parameter
+space in comparison to the statements made in earlier considerations [McDonald
+and Plischke, Phys. Rev. B 27 (1983) 201]. Our research on symmetry breaking in
+a strongly damped pendulum is relevant to an understanding of phenomena of
+dynamic symmetry breaking and rectification in a pure ac driven semiconductor
+superlattices.",0409572v1
+2004-10-19,Strongly inhibited transport of a 1D Bose gas in a lattice,"We report the observation of strongly damped dipole oscillations of a quantum
+degenerate 1D atomic Bose gas in a combined harmonic and optical lattice
+potential. Damping is significant for very shallow axial lattices (0.25 photon
+recoil energies), and increases dramatically with increasing lattice depth,
+such that the gas becomes nearly immobile for times an order of magnitude
+longer than the single-particle tunneling time. Surprisingly, we see no
+broadening of the atomic quasimomentum distribution after damped motion. Recent
+theoretical work suggests that quantum fluctuations can strongly damp dipole
+oscillations of 1D atomic Bose gas, providing a possible explanation for our
+observations.",0410491v3
+2005-08-10,Collective oscillations of a quasi one dimensional Bose condensate under damping,"Influence of the damping on collective oscillations of a one-dimensional
+trapped Bose gas in the mean field regime has been studied. Using the
+phenomenological damping approach developed by L.P. Pitaevskii, modified
+variational equations for the parameters of the condensate wave function is
+derived. Analytical expressions for the condensate parameters in equilibrium
+state have been obtained. Bistability in nonlinear oscillations of the
+condensate under periodic variations of the trap potential is predicted. The
+predictions of the modified variational approach are confirmed by full
+numerical simulations of the 1D GP equation with the damping.",0508262v1
+2005-08-11,Influence of layer defects on the damping in ferroelectric thin films,"A Green's function technique for a modified Ising model in a transverse field
+is applied, which allows to calculate the damping of the elementary excitations
+and the phase transition temperature of ferroelectric thin films with
+structural defects. Based on an analytical expression for the damping function,
+we analyze its dependence on temperature, film thickness and interaction
+strength numerically. The results demonstrate that defect layers in
+ferroelectric thin films, layers with impurities or vacancies as well as layers
+with dislocations are able to induce a strong increase of the damping due to
+different exchange interactions within the defect layers. The results are in
+good agreement with experimental data for thin ferroelectric films with
+different thickness.",0508287v1
+2007-02-23,Parametric Resonance of Optically Trapped Aerosols,"The Brownian dynamics of an optically trapped water droplet are investigated
+across the transition from over to under-damped oscillations. The spectrum of
+position fluctuations evolves from a Lorentzian shape typical of over-damped
+systems (beads in liquid solvents), to a damped harmonic oscillator spectrum
+showing a resonance peak. In this later under-damped regime, we excite
+parametric resonance by periodically modulating the trapping power at twice the
+resonant frequency. The power spectra of position fluctuations are in excellent
+agreement with the obtained analytical solutions of a parametrically modulated
+Langevin equation.",0702557v1
+2007-03-22,Spin-Torque Ferromagnetic Resonance Measurements of Damping in Nanomagnets,"We measure the magnetic damping parameter a in thin film CoFeB and permalloy
+(Py) nanomagnets at room temperature using ferromagnetic resonance driven by
+microwave frequency spin-transfer torque. We obtain $\alpha_{CoFeB} = 0.014 \pm
+0.003$ and $\alpha_{Py}=0.010 \pm 0.002$, values comparable to measurements for
+extended thin films, but significantly less than the effective damping
+determined previously for similar nanomagnets by fits to time-domain studies of
+large-angle magnetic excitations and magnetic reversal. The greater damping
+found for the large amplitude nanomagnet dynamics is attributed to the
+nonlinear excitation of non-uniform magnetic modes.",0703577v1
+2007-02-28,Numerical Model For Vibration Damping Resulting From the First Order Phase Transformations,"A numerical model is constructed for modelling macroscale damping effects
+induced by the first order martensite phase transformations in a shape memory
+alloy rod. The model is constructed on the basis of the modified
+Landau-Ginzburg theory that couples nonlinear mechanical and thermal fields.
+The free energy function for the model is constructed as a double well function
+at low temperature, such that the external energy can be absorbed during the
+phase transformation and converted into thermal form. The Chebyshev spectral
+methods are employed together with backward differentiation for the numerical
+analysis of the problem. Computational experiments performed for different
+vibration energies demonstrate the importance of taking into account damping
+effects induced by phase transformations.",0702172v1
+2005-04-22,Constraint damping in the Z4 formulation and harmonic gauge,"We show that by adding suitable lower-order terms to the Z4 formulation of
+the Einstein equations, all constraint violations except constant modes are
+damped. This makes the Z4 formulation a particularly simple example of a
+lambda-system as suggested by Brodbeck et al. We also show that the Einstein
+equations in harmonic coordinates can be obtained from the Z4 formulation by a
+change of variables that leaves the implied constraint evolution system
+unchanged. Therefore the same method can be used to damp all constraints in the
+Einstein equations in harmonic gauge.",0504114v2
+2005-07-05,Universality of Highly Damped Quasinormal Modes for Single Horizon Black Holes,"It has been suggested that the highly damped quasinormal modes of black holes
+provide information about the microscopic quantum gravitational states
+underlying black hole entropy. This interpretation requires the form of the
+highly damped quasinormal mode frequency to be universally of the form:
+$\hbar\omega_R = \ln(l)kT_{BH}$, where $l$ is an integer, and $T_{BH}$ is the
+black hole temperature. We summarize the results of an analysis of the highly
+damped quasinormal modes for a large class of single horizon, asymptotically
+flat black holes.",0507019v1
+2005-09-07,Massive vector field perturbations in the Schwarzschild background: stability and quasinormal spectrum,"We consider the perturbations of the massive vector field around
+Schwarzschild black hole, (generally, with non-vanishing $\Lambda$ - term). The
+monopole massive vector perturbation equations can be reduced to a single
+wave-like equation. We have proved the stability against these perturbations
+and investigated the quasinormal spectrum. The quasinormal behaviour for
+Schwarzschild black hole is quite unexpected: the fundamental mode and all
+higher overtones shows totally different dependence on the mass of the field
+$m$: as $m$ is increasing, the damping rate of the fundamental mode is
+decreasing, what results in appearing of the infinitely long living modes,
+while, on contrary, damping rate of all higher overtones are increasing, and
+their real oscillation frequencies gradually go to tiny values. Thereby, for
+all higher overtones, almost non-oscillatory, damping modes can exist. In the
+limit of asymptotically high damping, $Re \omega$ goes to $ln3/(8 \pi M)$,
+while imaginary part shows equidistant behaviour with spacing $Im \omega_{n+1}-
+Im \omega_{n}=i/4M$. In addition, we have found quasinormal spectrum of massive
+vector field for Schwarzschild-anti-de Sitter black hole.",0509026v3
+2006-11-27,The Mystery of the Asymptotic Quasinormal Modes of Gauss-Bonnet Black Holes,"We analyze the quasinormal modes of $D$-dimensional Schwarzschild black holes
+with the Gauss-Bonnet correction in the large damping limit and show that
+standard analytic techniques cannot be applied in a straightforward manner to
+the case of infinite damping. However, by using a combination of analytic and
+numeric techniques we are able to calculate the quasinormal mode frequencies in
+a range where the damping is large but finite. We show that for this damping
+region the famous $\ln(3)$ appears in the real part of the quasinormal mode
+frequency. In our calculations, the Gauss-Bonnet coupling, $\alpha$, is taken
+to be much smaller than the parameter $\mu$, which is related to the black hole
+mass.",0611139v1
+1995-09-22,Damping rate of neutrinos in the singlet Majoron model,"The damping rate and free path of neutrinos in the singlet Majoron model have
+been calculated including both finite temperature and symmetry breaking
+effects. The behaviour of right- and left-handed fermions are found inherently
+different. While the damping rates of the left-handed leptons are essentially
+model independent, e.g. directly applicable to the Standard Model, for the
+right-handed particles the rates are crucially sensitive to parameters of the
+scalar sector. In general, the damping rates are fairly large. The possibility
+of the right-handed neutrinos to penetrate deep into the broken phase in the
+electroweak phase transition still remains, however, for some parts of
+parameter space.",9509359v1
+1996-09-25,The hot baryon violation rate is $O(α_W^5 T^4)$,"The rate per unit volume for anomalous electroweak baryon number violation at
+high temperatures, in the symmetric phase, has been estimated in the literature
+to be $O(\alpha_W^4 T^4)$ based on simple scaling arguments. We argue that
+damping effects in the plasma suppress the rate by an extra power of $\alpha_W$
+to give $O(\alpha_W^5 T^4)$. We show how to understand this effect in a variety
+of ways ranging from an effective description of the long-distance modes
+responsible for baryon number violation, to a microscopic picture of the
+short-distance modes responsible for damping. In particular, we resolve an old
+controversy as to whether damping effects are relevant. Finally, we argue that
+similar damping effects should occur in numerical simulations of the rate in
+classical thermal field theory on a spatial lattice, and we point out a
+potential problem with simulations in the literature that have not found such
+an effect.",9609481v1
+2001-03-29,Phase transition dynamics in the hot Abelian Higgs model,"We present a detailed numerical study of the equilibrium and non-equilibrium
+dynamics of the phase transition in the finite-temperature Abelian Higgs model.
+Our simulations use classical equations of motion both with and without
+hard-thermal-loop corrections, which take into account the leading quantum
+effects. From the equilibrium real-time correlators, we determine the Landau
+damping rate, the plasmon frequency and the plasmon damping rate. We also find
+that, close to the phase transition, the static magnetic field correlator shows
+power-law magnetic screening at long distances. The information about the
+damping rates allows us to derive a quantitative prediction for the number
+density of topological defects formed in a phase transition. We test this
+prediction in a non-equilibrium simulation and show that the relevant time
+scale for defect formation is given by the Landau damping rate.",0103311v1
+1996-04-12,Onset of Rotational Damping in Superdeformed Nuclei,"We discuss damping of the collective rotational motion in $A\sim 150$
+superdeformed nuclei by means of a shell model combining the cranked Nilsson
+mean-filed and the surface-delta two-body residual force. It is shown that,
+because of the shell structure associated with the superdeformed mean-field,
+onset energy of the rotational damping becomes $E_x \sim 2-3 $ MeV above yrast
+line, which is much higher than in normal deformed nuclei. The mechanism of the
+shell structure effect is investigated through detailed analysis of level
+densities in superdeformed nuclei. It is predicted the onset of damping varies
+in different supedeformed nuclei along with variation in the single-particle
+structure at the Fermi surface.",9604015v1
+2001-09-12,The damping width of giant dipole resonances of cold and hot nuclei: a macroscopic model,"A phenomenological macroscopic model of the Giant Dipole Resonance (GDR)
+damping width of cold- and hot-nuclei with ground-state spherical and
+near-spherical shapes is developed. The model is based on a generalized Fermi
+Liquid model which takes into account the nuclear surface dynamics. The
+temperature dependence of the GDR damping width is accounted for in terms of
+surface- and volume-components. Parameter-free expressions for the damping
+width and the effective deformation are obtained. The model is validated with
+GDR measurements of the following nuclides, $^{39,40}$K, $^{42}$Ca, $^{45}$Sc,
+$^{59,63}$Cu, $^{109-120}$Sn,$^{147}$Eu, $^{194}$Hg, and $^{208}$Pb, and is
+compared with the predictions of other models.",0109034v1
+2006-01-31,Small damping approach in Fermi-liquid theory,"The validity of small damping approximation (SDA) for the quasi-classical
+description of the averaged properties of nuclei at high temperatures is
+studied within the framework of collisional kinetic theory. The isoscalar
+collective quadrupole vibrations in hot nuclei are considered. We show that the
+extension of the SDA, by accounting for the damping of the distribution
+function $\delta f$ in the collision integral reduces the rate of variation
+with temperature of the Fermi surface distortion effects. The damping of the
+$\delta f$ in the collision integral increases significantly the collisional
+width of the giant quadrupole resonance (GQR) for small enough values of the
+relaxation time. The temperature dependence of the eigenenergy of the GQR
+becomes much more weaker than in the corresponding SDA case.",0601094v1
+2001-11-05,Damping of transversal plasma-electron oscillations and waves in low-collision electron-ion plasmas,"Previously developed method for finding asymptotic solutions of Vlasov
+equations using two-dimensional (in coordinate x and time t) Laplace transform
+is here applied to consider transversal oscillations and waves in low-collision
+quasi-neutral (n_i \simeq n_e) Maxwellian electron-ion plasmas. We obtain two
+branches of electron waves: the ubiquitous one of high-frequency and
+high-velocity oscillations and the unusual low-velocity one. Taking into
+account Coulomb collisions in the limit m_e << m_i, \bar{v_i} << \bar{v_e}, and
+T_e m_e << T_i m_i results in expressions for transversal plasma-electron
+oscillation/wave decrements with a damping of the low-velocity electron branch
+\sim n_i^{1/3}/\bar{v}_e^{4/3}, where n_i is the ion density and \bar{v}_e is
+the mean electron velocity. It ought to rehabilitate Vlasov principal value
+prescription for relevant integrals, but to supplement it with representation
+of an asymptotical solution as a sum of exponents (not a single one).
+""Non-damping"" kinematical waves in low-collision plasma transform in the
+damping ones at reasonably chosen iteration process.",0111014v3
+2002-03-13,Enhanced radiative ion cooling,"Enhanced radiative cooling of ion beams in storage rings and Robinson's
+damping criterion are discussed.",0203036v1
+2003-05-24,Impact of the Wiggler Coherent Synchrotron Radiation Impedance on the Beam Instability,"Coherent Synchrotron Radiation (CSR) can play an important role by not only
+increasing the energy spread and emittance of a beam, but also leading to a
+potential instability. Previous studies of the CSR induced longitudinal
+instability were carried out for the CSR impedance due to dipole magnets.
+However, many storage rings include long wigglers where a large fraction of the
+synchrotron radiation is emitted. This includes high-luminosity factories such
+as DAPHNE, PEP-II, KEK-B, and CESR-C as well as the damping rings of future
+linear colliders. In this paper, the instability due to the CSR impedance from
+a wiggler is studied assuming a large wiggler parameter $K$. The primary
+consideration is a low frequency microwave-like instability, which arises near
+the pipe cut-off frequency. Detailed results are presented on the growth rate
+and threshold for the damping rings of several linear collider designs.
+Finally, the optimization of the relative fraction of damping due to the
+wiggler systems is discussed for the damping rings.",0305107v1
+2004-09-13,Landau damping in thin films irradiated by a strong laser field,"The rate of linear collisionless damping (Landau damping) in a classical
+electron gas confined to a heated ionized thin film is calculated. The general
+expression for the imaginary part of the dielectric tensor in terms of the
+parameters of the single-particle self-consistent electron potential is
+obtained. For the case of a deep rectangular well, it is explicitly calculated
+as a function of the electron temperature in the two limiting cases of specular
+and diffuse reflection of the electrons from the boundary of the
+self-consistent potential. For realistic experimental parameters, the
+contribution of Landau damping to the heating of the electron subsystem is
+estimated. It is shown that for films with a thickness below about 100 nm and
+for moderate laser intensities it may be comparable with or even dominate over
+electron-ion collisions and inner ionization.",0409062v1
+1996-06-24,Quantum damping of position due to energy measurements,"Quantum theory for measurements of energy is introduced and its consequences
+for the average position of monitored dynamical systems are analyzed. It turns
+out that energy measurements lead to a localization of the expectation values
+of other observables. This is manifested, in the case of position, as a damping
+of the motion without classical analogue. Quantum damping of position for an
+atom bouncing on a reflecting surface in presence of a homogeneous
+gravitational field is dealt in detail and the connection with an experiment
+already performed in the classical regime is studied. We show that quantum
+damping is testable provided that the same measurement strength obtained in the
+experimental verification of the quantum Zeno effect in atomic spectroscopy [W.
+M. Itano et al., Phys. Rev. A {\bf 41}, 2295 (1990)] is made available.",9606024v1
+2006-12-17,Influence of a classical homogeneous gravitational field on dissipative dynamics of the Jaynes-Cummings model with phase damping,"In this paper, we study the dissipative dynamics of the Jaynes-Cummings model
+with phase damping in the presence of a classical homogeneous gravitational
+field. The model consists of a moving two-level atom simultaneously exposed to
+the gravitational field and a single-mode traveling radiation field in the
+presence of the phase damping. We present a quantum treatment of the internal
+and external dynamics of the atom based on an alternative su(2) dynamical
+algebraic structure. By making use of the super-operator technique, we obtain
+the solution of the master equation for the density operator of the quantum
+system, under the Markovian approximation. Assuming that initially the
+radiation field is prepared in a Glauber coherent state and the two-level atom
+is in the excited state, we investigate the influence of gravity on the
+temporal evolution of collapses and revivals of the atomic population
+inversion, atomic dipole squeezing, atomic momentum diffusion, photon counting
+statistics and quadrature squeezing of the radiation field in the presence of
+phase damping.",0612143v2
+2007-04-25,Theory of weakly damped free-surface flows: a new formulation based on potential flow solutions,"Several theories for weakly damped free-surface flows have been formulated.
+In this paper we use the linear approximation to the Navier-Stokes equations to
+derive a new set of equations for potential flow which include dissipation due
+to viscosity. A viscous correction is added not only to the irrotational
+pressure (Bernoulli's equation), but also to the kinematic boundary condition.
+The nonlinear Schr\""odinger (NLS) equation that one can derive from the new set
+of equations to describe the modulations of weakly nonlinear, weakly damped
+deep-water gravity waves turns out to be the classical damped version of the
+NLS equation that has been used by many authors without rigorous justification.",0704.3352v1
+2007-05-25,The Secular Evolution of a Close Ring-Satellite System: The Excitation of Spiral Bending Waves at a Nearby Gap Edge,"The secular perturbations exerted by an inclined satellite orbiting in a gap
+in a broad planetary ring tends to excite the inclinations of the nearby ring
+particles, and the ring's self-gravity can allow that disturbance to propagate
+away in the form of a spiral bending wave. The amplitude of this spiral bending
+wave is determined, as well as the wavelength, which shrinks as the waves
+propagate outwards due to the effects of the central planet's oblateness. The
+excitation of these bending waves also damps the satellite's inclination I.
+This secular I damping is also compared to the inclination excitation that is
+due to the satellite's many other vertical resonances in the ring, and the
+condition for inclination damping is determined. The secular I damping is
+likely responsible for confining the orbits of Saturn's two known gap-embedded
+moons, Pan and Daphnis, to the ring plane.",0705.3797v1
+2007-06-15,Anticorrelation between temperature and fluctuations in moderately damped Josephson junctions,"We study the influence of dissipation on the switching current statistics of
+moderately damped Josephson junctions. Different types of both low- and high-
+$T_c$ junctions with controlled damping are studied. The damping parameter of
+the junctions is tuned in a wide range by changing temperature, magnetic field,
+gate voltage, introducing a ferromagnetic layer or in-situ capacitive shunting.
+A paradoxical collapse of switching current fluctuations occurs with increasing
+$T$ in all studied junctions. The phenomenon critically depends on dissipation
+in the junction and is explained by interplay of two counteracting consequences
+of thermal fluctuations, which on the one hand assist in premature switching
+into the resistive state and on the other hand help in retrapping back to the
+superconducting state. This is one of the rare examples of anticorrelation
+between temperature and fluctuation amplitude of a physically measurable
+quantity.",0706.2248v1
+2007-08-06,Collisionless damping of electron waves in non-Maxwellian plasma,"In this paper we have criticized the so-called Landau damping theory. We have
+analyzed solutions of the standard dispersion equations for longitudinal
+(electric) and transversal (electromagnetic and electron) waves in
+half-infinite slab of the uniform collisionless plasmas with non-Maxwellian and
+Maxwellian-like electron energy distribution functions. One considered the most
+typical cases of both the delta-function type distribution function (the plasma
+stream with monochromatic electrons) and distribution functions, different from
+Maxwellian ones as with a surplus as well as with a shortage in the Maxwellian
+distribution function tail. It is shown that there are present for the
+considered cases both collisionless damping and also non-damping electron waves
+even in the case of non-Maxwellian distribution function.",0708.0748v5
+2007-08-14,Preliminary Results on Vibration Damping Properties of Nanoscale-Reinforced Composite Materials,"The focus in this paper is an analysis of existing state of the arts directed
+toward the development of the next generation of vibration damping systems. The
+research work concentrates on an investigation related to
+nanoparticles/fibres/tubes-reinforced materials and coatings dynamic
+characterization and modeling of the fundamental phenomena that control
+relationships between structure and damping/mechanical properties of the
+materials. We simulated composite materials using finite element and mesh free
+methods, using a hollow shell representation of the individual nanotube/fiber.
+Results of the research work will provide a platform for the development of
+nanoparticle-reinforced damping materials that are light-weight, vibration and
+shock resistant. The outcome of the research work is expected to have
+wide-ranging technical benefits with direct relevance to industry in areas of
+transportation (aerospace, automotive, rail), electronics and civil
+infrastructure development.",0708.1821v1
+2007-08-18,Non-Riemannian geometrical asymmetrical damping stresses on the Lagrange instability of shear flows,"It is shown that the physical interpretation of Elie Cartan three-dimensional
+space torsion as couple asymmetric stress, has the effect of damping,
+previously Riemannian unstable Couette planar shear flow, leading to stability
+of the flow in the Lagrangean sense. Actually, since the flow speed is
+inversely proportional to torsion, it has the effect of causing a damping in
+the planar flow atenuating the instability effect. In this sense we may say
+that Cartan torsion induces shear viscous asymmetric stresses in the fluid,
+which are able to damp the instability of the flow. The stability of the flow
+is computed from the sectional curvature in non-Riemannian three-dimensional
+manifold. Marginal stability is asssumed by making the sectional non-Riemannian
+curvature zero, which allows us to determine the speeds of flows able to induce
+this stability. The ideas discussed here show that torsion plays the
+geometrical role of magnetic field in hydromagnetic instability of Couette
+flows recently investigated by Bonnano and Urpin (PRE, (2007,in press) can be
+extended and applied to plastic flows with microstructure defects. Recently
+Riemannian asymmetric stresses in magnetohydrodynamics (MHD) have been
+considered by Billig (2004).",0708.2467v1
+2007-12-07,State transition of a non-Ohmic damping system in a corrugated plane,"Anomalous transport of a particle subjected to non-Ohmic damping of the power
+$\delta$ in a tilted periodic potential is investigated via Monte Carlo
+simulation of generalized Langevin equation. It is found that the system
+exhibits two relative motion modes: the locking state and the running state.
+Under the surrounding of sub-Ohmic damping ($0<\delta<1$), the particle should
+transfer into a running state from a locking state only when local minima of
+the potential vanish; hence the particle occurs a synchronization oscillation
+in its mean displacement and mean square displacement (MSD). In particular, the
+two motion modes are allowed to coexist in the case of super-Ohmic damping
+($1<\delta<2$) for moderate driving forces, namely, where exists double centers
+in the velocity distribution. This induces the particle having faster
+diffusion, i.e., its MSD reads $<\Delta x^2(t)> = 2D^{(\delta)}_{eff}
+t^{\delta_{eff}}$. Our result shows that the effective power index
+$\delta_{\textmd{eff}}$ can be enhanced and is a nonmonotonic function of the
+temperature and the driving force. The mixture effect of the two motion modes
+also leads to a breakdown of hysteresis loop of the mobility.",0712.1070v1
+2007-12-25,The damped Pinney equation and its applications to dissipative quantum mechanics,"The work considers the damped Pinney equation, defined as the model arising
+when a linear in velocity damping term is included in the Pinney equation. In
+the general case the resulting equation does not admit Lie point symmetries or
+is reducible to a simpler form by any obvious coordinate transformation. In
+this context the method of Kuzmak-Luke is applied to derive a perturbation
+solution, for weak damping and slow time-dependence of the frequency function.
+The perturbative and numerical solutions are shown to be in good agreement. The
+results are applied to examine the time-evolution of Gaussian shaped
+wave-functions in the Kostin formulation of dissipative quantum mechanics.",0712.4083v3
+2008-01-01,Non-linear equations for electron waves in Maxwellian low-collision ion-electron plasmas,"The before described general principles and methodology of calculating
+electron wave propagation in homogeneous isotropic half-infinity slab of
+Maxwellian plasma with indefinite but in principal value sense taken integrals
+in characteristic equations, and the use of 2D Laplace transform method are
+applied to an evaluation of collision damping decrements of plane electron
+longitudinal and transverse waves. Damping decrement tends to infinity when the
+wave frequency tends to electron Langmuir frequency from above values. We
+considered recurrent relations for amplitudes of the overtones which form in
+their sum the all solution of the plasma wave non-linear equations including
+collision damping and quadratic (non-linear) terms. Collisionless damping at
+frequencies more the Langmuir one is possible only in non-Maxwellian plasmas.",0801.0286v2
+2008-02-22,Radiative Damping and Functional Differential Equations,"We propose a general technique to solve the classical many-body problem with
+radiative damping. We modify the short-distance structure of Maxwell
+electrodynamics. This allows us to avoid runaway solutions as if we had a
+covariant model of extended particles. The resulting equations of motion are
+functional differential equations (FDEs) rather than ordinary differential
+equations. Using recently developed numerical techniques for stiff FDEs, we
+solve these equations for the one-body central force problem with radiative
+damping with a view to benchmark our new approach. Our results indicate that
+locally the magnitude of radiation damping may be well approximated by the
+standard third-order expression but the global properties of our solutions are
+dramatically different. We comment on the two body problem and applications to
+quantum field theory and quantum mechanics.",0802.3390v2
+2008-04-24,Analytic approximate seismology of transversely oscillating coronal loops,"We present an analytic approximate seismic inversion scheme for damped
+transverse coronal loop oscillations based on the thin tube and thin boundary
+approximation for computing the period and the damping time. Asymptotic
+expressions for the period and damping rate are used to illustrate the process
+of seismological inversion in a simple and easy to follow manner. The inversion
+procedure is formulated in terms of two simple functions, which are given by
+simple closed expressions. The analytic seismic inversion shows that an
+infinite amount of 1-dimensional equilibrium models can reproduce the observed
+periods and damping times. It predicts a specific range of allowable values for
+the Alfven travel time and lower bounds for the density contrast and the
+inhomogeneity length scale. When the results of the present analytic seismic
+inversion are compared with those of a previous numerical inversion, excellent
+agreement is found up to the point that the analytic seismic inversion emerges
+as a tool for validating results of numerical inversions. Actually it helped us
+to identify and correct inaccuracies in a previous numerical investigation.",0804.3877v1
+2008-10-21,On Wigner functions and a damped star product in dissipative phase-space quantum mechanics,"Dito and Turrubiates recently introduced an interesting model of the
+dissipative quantum mechanics of a damped harmonic oscillator in phase space.
+Its key ingredient is a non-Hermitian deformation of the Moyal star product
+with the damping constant as deformation parameter. We compare the
+Dito-Turrubiates scheme with phase-space quantum mechanics (or deformation
+quantization) based on other star products, and extend it to incorporate Wigner
+functions. The deformed (or damped) star product is related to a complex
+Hamiltonian, and so necessitates a modified equation of motion involving
+complex conjugation. We find that with this change the Wigner function
+satisfies the classical equation of motion. This seems appropriate since
+non-dissipative systems with quadratic Hamiltonians share this property.",0810.3893v1
+2009-01-08,Grand-mother clocks and quiet lasers,"Galileo noted in the 16th century that the period of oscillation of a
+pendulum is almost independent of the amplitude. However, such a pendulum is
+damped by air friction. The latter may be viewed as resulting from air
+molecules getting in contact with the pendulum. It follows that air friction,
+not only damps the oscillation, but also introduces randomness. In the
+so-called ``grand-mother'' clock, discovered by Huygens in the 18th century,
+damping is compensated for, on the average, by an escapement mechanism driven
+by a falling weight. The purpose of this paper is to show that such a clock is,
+in its idealized form, a quiet oscillator. By ``quiet'' we mean that in spite
+of the randomness introduced by damping, the dissipated power (viewed as the
+oscillator output) does not fluctuate slowly. Comparison is made with quiet
+laser oscillators discovered theoretically in 1984. Because the input power
+does not fluctuate in both the mechanical oscillator and the quiet laser
+oscillator, the output power does not fluctuate at small Fourier frequencies,
+irrespectively of the detailed mechanisms involved.",0901.0983v1
+2009-01-15,Interaction of fast charged projectiles with two-dimensional electron gas: Interaction and disorder effects,"The results of a theoretical investigation on the stopping power of ions
+moving in a disordered two-dimensional degenerate electron gas are presented.
+The stopping power for an ion is calculated employing linear response theory
+using the dielectric function approach. The disorder, which leads to a damping
+of plasmons and quasiparticles in the electron gas, is taken into account
+through a relaxation time approximation in the linear response function. The
+stopping power for an ion is calculated in both the low- and high-velocity
+limits. In order to highlight the effects of damping we present a comparison of
+our analytical and numerical results, in the case of point-like ions, obtained
+for a non-zero damping with those for a vanishing damping. It is shown that the
+equipartition sum rule first formulated by Lindhard and Winther for
+three-dimensional degenerate electron gas does not necessarily hold in
+two-dimensions. We have generalized this rule introducing an effective
+dielectric function. In addition some new results for two-dimensional
+interacting electron gas have been obtained. In this case the
+exchange-correlation interactions of electrons are considered via
+local-field-corrected dielectric function.",0901.2249v1
+2009-02-01,Non-Markovian Analysis of the Phase Damped Jaynes-Cummings Model in the Presence of a Classical Homogeneous Gravitational Field,"In this paper, the non-Markovian dissipative dynamics of the phase damped
+Jaynes-Cummings model in the presence of a classical homogeneous gravitational
+field will be analyzed. The model consists of a moving two-level atom
+simultaneously exposed to the gravitational field and a single-mode traveling
+radiation field in the presence of a non-Markovian phase damping mechanism.
+First, the non-Markovian master equation for the reduced density operator of
+the system in terms of a Hamiltonian describing the atom-field interaction in
+the presence of a homogeneous gravitational field will be presented. Then, the
+super-operator technique will be generalized and an exact solution of the
+non-Markovian master equation will be obtained. Assuming that initially the
+radiation field is prepared in a Glauber coherent state and the two-level atom
+is in the excited state, the non-Markovian effects on the temporal evolution of
+collapses and revivals of the atomic population inversion and photon counting
+statistics of the radiation field in the presence of both the phase damping and
+a homogeneous gravitational field will be investigated.",0902.0114v1
+2009-05-04,Models of Damped Oscillators in Quantum Mechanics,"We consider several models of the damped oscillators in nonrelativistic
+quantum mechanics in a framework of a general approach to the dynamics of the
+time-dependent Schroedinger equation with variable quadratic Hamiltonians. The
+Green functions are explicitly found in terms of elementary functions and the
+corresponding gauge transformations are discussed. The factorization technique
+is applied to the case of a shifted harmonic oscillator. The time-evolution of
+the expectation values of the energy related operators is determined for two
+models of the quantum damped oscillators under consideration. The classical
+equations of motion for the damped oscillations are derived for the
+corresponding expectation values of the position operator.",0905.0507v6
+2009-05-28,Resonant Nonlinear Damping of Quantized Spin Waves in Ferromagnetic Nanowires,"We use spin torque ferromagnetic resonance to measure the spectral properties
+of dipole-exchange spin waves in permalloy nanowires. Our measurements reveal
+that geometric confinement has a profound effect on the damping of spin waves
+in the nanowire geometry. The damping parameter of the lowest-energy quantized
+spin wave mode depends on applied magnetic field in a resonant way and exhibits
+a maximum at a field that increases with decreasing nanowire width. This
+enhancement of damping originates from a nonlinear resonant three-magnon
+confluence process allowed at a particular bias field value determined by
+quantization of the spin wave spectrum in the nanowire geometry.",0905.4699v2
+2009-06-01,Effect of Decoherence in Ekert-Protocol,"We have examined the effect of the decoherence in the Ekert91 quantum
+cryptographic protocol. In order to explore this issue we have introduced two
+major decoherences, the depolarizing channel and the generalized amplitude
+damping, between the singlet source and one of the legitimate users. It is
+shown that the depolarizing channel disentangles the quantum channel more
+easily than the generalized amplitude damping. This fact indicates that the
+Ekert protocol is more robust to the generalized amplitude damping. We also
+have computed the Bell inequality to check the robustness or weakness of the
+Ekert91 protocol. Computation of the Bell inequality also confirms the
+robustness of the Ekert91 protocol to the generalized amplitude damping
+compared to the depolarizing channel.",0906.0233v1
+2009-08-05,Surface plasmon lifetime in metal nanoshells,"The lifetime of localized surface plasmon plays an important role in many
+aspects of plasmonics and its applications. In small metal nanostructures, the
+dominant mechanism restricting plasmon lifetime is size-dependent Landau
+damping. We performed quantum-mechanical calculations of Landau damping for the
+bright surface plasmon mode in a metal nanoshell. In contrast to the
+conventional model based on the electron surface scattering, we found that the
+damping rate decreases as the nanoshell thickness is reduced. The origin of
+this behavior is traced to the spatial distribution of plasmon local field
+inside the metal shell. We also found that, due to interference of electron
+scattering amplitudes from nanoshell's two metal surfaces, the damping rate
+exhibits pronounced quantum beats with changing shell thickness.",0908.0647v3
+2009-08-12,Coarse Grained Simulations of a Small Peptide: Effects of Finite Damping and Hydrodynamic Interactions,"In the coarse grained Brownian Dynamics simulation method the many solvent
+molecules are replaced by random thermal kicks and an effective friction acting
+on the particles of interest. For Brownian Dynamics the friction has to be so
+strong that the particles' velocities are damped much faster than the duration
+of an integration timestep. Here we show that this conceptual limit can be
+dropped with an analytic integration of the equations of damped motion. In the
+resulting Langevin integration scheme our recently proposed approximate form of
+the hydrodynamic interactions between the particles can be incorparated
+conveniently, leading to a fast multi-particle propagation scheme, which
+captures more of the short-time and short-range solvent effects than standard
+BD. Comparing the dynamics of a bead-spring model of a short peptide, we
+recommend to run simulations of small biological molecules with the Langevin
+type finite damping and to include the hydrodynamic interactions.",0908.1685v1
+2009-09-01,Quantum Stackelberg duopoly in the presence of correlated noise,"We study the influence of entanglement and correlated noise using correlated
+amplitude damping, depolarizing and phase damping channels on the quantum
+Stackelberg duopoly. Our investigations show that under the action of amplitude
+damping channel a critical point exists for unentangled initial state as well,
+at which firms get equal payoffs. The game becomes a follower advantage game
+when the channel is highly decohered. Two critical points corresponding to two
+values of the entanglement angle are found in the presence of correlated noise.
+Within the range of these limits of entanglement angle, the game is follower
+advantage game. In case of depolarizing channel, the payoffs of the two firms
+are strongly influenced by the memory parameter. The presence of quantum memory
+ensures the existence of Nash equilibrium for the entire range of decoherence
+and entanglement parameters for both the channels. A local maximum in the
+payoffs is observed which vanishes as the channel correlation increases.
+Moreover, under the influence of depolarizing channel, the game is always a
+leader advantage game. Furthermore, it is seen that phase damping channel does
+not effect the outcome of the game.",0909.0063v2
+2009-09-04,Second sound dipole mode in a partially Bose-Einstein condensed gas,"We study the second sound dipole mode in a partially Bose-Einstein condensed
+gas. This mode is excited by spatially separating and releasing the
+center-of-mass of the Bose-Einstein condensate (BEC) with respect to the
+thermal cloud, after which the equilibration is observed. The oscillation
+frequency and the damping rate of this mode is studied for different harmonic
+confinements and temperatures. The measured damping rates close to the
+collisionless regime are found to be in good agreement with Landau damping. For
+increasing hydrodynamicity of the cloud we observe an increase of the damping.",0909.0886v1
+2009-12-30,Finite dimensional attractor for a composite system of wave/plate equations with localised damping,"The long-term behaviour of solutions to a model for acoustic-structure
+interactions is addressed; the system is comprised of coupled semilinear wave
+(3D) and plate equations with nonlinear damping and critical sources. The
+questions of interest are: existence of a global attractor for the dynamics
+generated by this composite system, as well as dimensionality and regularity of
+the attractor. A distinct and challenging feature of the problem is the
+geometrically restricted dissipation on the wave component of the system. It is
+shown that the existence of a global attractor of finite fractal dimension --
+established in a previous work by Bucci, Chueshov and Lasiecka (Comm. Pure
+Appl. Anal., 2007) only in the presence of full interior acoustic damping --
+holds even in the case of localised dissipation. This nontrivial generalization
+is inspired by and consistent with the recent advances in the study of wave
+equations with nonlinear localised damping.",0912.5464v2
+2010-02-12,Features of ion acoustic waves in collisional plasmas,"The effects of friction on the ion acoustic (IA) wave in fully and partially
+ionized plasmas are studied. In a quasi-neutral electron-ion plasma the
+friction between the two species cancels out exactly and the wave propagates
+without any damping. If the Poisson equation is used instead of the
+quasi-neutrality, however, the IA wave is damped and the damping is dispersive.
+In a partially ionized plasma, the collisions with the neutrals modify the IA
+wave beyond recognition. For a low density of neutrals the mode is damped. Upon
+increasing the neutral density, the mode becomes first evanescent and then
+reappears for a still larger number of neutrals. A similar behavior is obtained
+by varying the mode wave-length. The explanation for this behavior is given. In
+an inhomogeneous plasma placed in an external magnetic field, and for
+magnetized electrons and un-magnetized ions, the IA mode propagates in any
+direction and in this case the collisions make it growing on the account of the
+energy stored in the density gradient. The growth rate is angle dependent. A
+comparison with the collision-less kinetic density gradient driven IA
+instability is also given.",1002.2502v1
+2010-02-18,Damping mechanisms for oscillations in solar prominences,"Small amplitude oscillations are a commonly observed feature in
+prominences/filaments. These oscillations appear to be of local nature, are
+associated to the fine structure of prominence plasmas, and simultaneous flows
+and counterflows are also present. The existing observational evidence reveals
+that small amplitude oscillations, after excited, are damped in short spatial
+and temporal scales by some as yet not well determined physical mechanism(s).
+Commonly, these oscillations have been interpreted in terms of linear
+magnetohydrodynamic (MHD) waves, and this paper reviews the theoretical damping
+mechanisms that have been recently put forward in order to explain the observed
+attenuation scales. These mechanisms include thermal effects, through
+non-adiabatic processes, mass flows, resonant damping in non-uniform media, and
+partial ionization effects. The relevance of each mechanism is assessed by
+comparing the spatial and time scales produced by each of them with those
+obtained from observations. Also, the application of the latest theoretical
+results to perform prominence seismology is discussed, aiming to determine
+physical parameters in prominence plasmas that are difficult to measure by
+direct means.",1002.3489v2
+2010-03-07,Theory of plasmon decay in dense plasmas and warm dense matter,"The decay of the Langmuir waves in dense plasmas is not accurately predicted
+by the prevalent Landau damping theory. A dielectric function theory is
+introduced, predicting much higher damping than the Landau damping theory. This
+strong damping is in better agreement with the experimentally observed data in
+metals. It is shown that the strong plasmon decay leads to the existence of a
+parameter regime where the backward Raman scattering is unstable while the
+forward Raman scattering is stable. This regime may be used to create intense
+x-ray pulses, by means of the the backward Raman compression. The optimal pulse
+duration and intensity is estimated.",1003.1523v2
+2010-04-12,Dissipative Transport of a Bose-Einstein Condensate,"We investigate the effects of impurities, either correlated disorder or a
+single Gaussian defect, on the collective dipole motion of a Bose-Einstein
+condensate of $^7$Li in an optical trap. We find that this motion is damped at
+a rate dependent on the impurity strength, condensate center-of-mass velocity,
+and interatomic interactions. Damping in the Thomas-Fermi regime depends
+universally on the disordered potential strength scaled to the condensate
+chemical potential and the condensate velocity scaled to the peak speed of
+sound. The damping rate is comparatively small in the weakly interacting
+regime, and the damping in this case is accompanied by strong condensate
+fragmentation. \textit{In situ} and time-of-flight images of the atomic cloud
+provide evidence that this fragmentation is driven by dark soliton formation.",1004.1891v2
+2010-05-23,Constraining phases of quark matter with studies of r-mode damping in neutron stars,"The r-mode instability in rotating compact stars is used to constrain the
+phase of matter at high density. The color-flavor-locked phase with kaon
+condensation (CFL-K0) and without (CFL) is considered in the temperature range
+10^8K < T <10^{11} K. While the bulk viscosity in either phase is only
+effective at damping the r-mode at temperatures T > 10^{11} K, the shear
+viscosity in the CFL-K0 phase is the only effective damping agent all the way
+down to temperatures T > 10^8 K characteristic of cooling neutron stars.
+However, it cannot keep the star from becoming unstable to gravitational wave
+emission for rotation frequencies f ~ 56-11 Hz at T ~ 10^8-10^9 K. Stars
+composed almost entirely of CFL or CFL-K0 matter are ruled out by observation
+of rapidly rotating neutron stars, indicating that dissipation at the
+quark-hadron interface or nuclear crust interface must play a key role in
+damping the instability.",1005.4161v1
+2010-07-07,Observational evidence of resonantly damped propagating kink waves in the solar corona,"In this Letter we establish clear evidence for the resonant absorption
+damping mechanism by analyzing observational data from the novel Coronal
+Multi-Channel Polarimeter (CoMP). This instrument has established that in the
+solar corona there are ubiquitous propagating low amplitude ($\approx$1 km
+s$^{-1}$) Alfv\'{e}nic waves with a wide range of frequencies. Realistically
+interpreting these waves as the kink mode from magnetohydrodynamic (MHD) wave
+theory, they should exhibit a frequency dependent damping length due to
+resonant absorption, governed by the TGV relation showing that transversal
+plasma inhomogeneity in coronal magnetic flux tubes causes them to act as
+natural low-pass filters. It is found that observed frequency dependence on
+damping length (up to about 8 mHz) can be explained by the kink wave
+interpretation and furthermore, the spatially averaged equilibrium parameter
+describing the length scale of transverse plasma density inhomogeneity over a
+system of coronal loops is consistent with the range of values estimated from
+TRACE observations of standing kink modes.",1007.1080v1
+2010-07-12,Variable damping and coherence in a high-density magnon gas,"We report on the fast relaxation behavior of a high-density magnon gas
+created by a parametric amplification process. The magnon gas is probed using
+the technique of spin-wave packet recovery by parallel parametric pumping.
+Experimental results show a damping behavior which is in disagreement with both
+the standard model of exponential decay and with earlier observations of
+non-linear damping. In particular, the inherent magnon damping is found to
+depend upon the presence of the parametric pumping field. A phenomenological
+model which accounts for the dephasing of the earlier injected magnons is in
+good agreement with the experimental data.",1007.1895v3
+2010-07-21,A low-power circuit for piezoelectric vibration control by synchronized switching on voltage sources,"In the paper, a vibration damping system powered by harvested energy with
+implementation of the so-called SSDV (synchronized switch damping on voltage
+source) technique is designed and investigated. In the semi-passive approach,
+the piezoelectric element is intermittently switched from open-circuit to
+specific impedance synchronously with the structural vibration. Due to this
+switching procedure, a phase difference appears between the strain induced by
+vibration and the resulting voltage, thus creating energy dissipation. By
+supplying the energy collected from the piezoelectric materials to the
+switching circuit, a new low-power device using the SSDV technique is proposed.
+Compared with the original self-powered SSDI (synchronized switch damping on
+inductor), such a device can significantly improve its performance of vibration
+control. Its effectiveness in the single-mode resonant damping of a composite
+beam is validated by the experimental results.",1007.3596v1
+2010-10-24,Long-time dynamics in plate models with strong nonlinear damping,"We study long-time dynamics of a class of abstract second order in time
+evolution equations in a Hilbert space with the damping term depending both on
+displacement and velocity. This damping represents the nonlinear strong
+dissipation phenomenon perturbed with relatively compact terms. Our main result
+states the existence of a compact finite dimensional attractor. We study
+properties of this attractor. We also establish the existence of a fractal
+exponential attractor and give the conditions that guarantee the existence of a
+finite number of determining functionals. In the case when the set of
+equilibria is finite and hyperbolic we show that every trajectory is attracted
+by some equilibrium with exponential rate. Our arguments involve a recently
+developed method based on the ""compensated"" compactness and quasi-stability
+estimates. As an application we consider the nonlinear Kirchhoff, Karman and
+Berger plate models with different types of boundary conditions and strong
+damping terms. Our results can be also applied to the nonlinear wave equations.",1010.4991v1
+2010-11-05,"Effects of Turbulence, Eccentricity Damping, and Migration Rate on the Capture of Planets into Mean Motion Resonance","Pairs of migrating extrasolar planets often lock into mean motion resonance
+as they drift inward. This paper studies the convergent migration of giant
+planets (driven by a circumstellar disk) and determines the probability that
+they are captured into mean motion resonance. The probability that such planets
+enter resonance depends on the type of resonance, the migration rate, the
+eccentricity damping rate, and the amplitude of the turbulent fluctuations.
+This problem is studied both through direct integrations of the full 3-body
+problem, and via semi-analytic model equations. In general, the probability of
+resonance decreases with increasing migration rate, and with increasing levels
+of turbulence, but increases with eccentricity damping. Previous work has shown
+that the distributions of orbital elements (eccentricity and semimajor axis)
+for observed extrasolar planets can be reproduced by migration models with
+multiple planets. However, these results depend on resonance locking, and this
+study shows that entry into -- and maintenance of -- mean motion resonance
+depends sensitively on migration rate, eccentricity damping, and turbulence.",1011.1486v1
+2010-11-21,Quasi-normal frequencies: Semi-analytic results for highly damped modes,"Black hole highly-damped quasi-normal frequencies (QNFs) are very often of
+the form (offset)} + i n (gap). We have investigated the genericity of this
+phenomenon for the Schwarzschild--deSitter (SdS) black hole by considering a
+model potential that is piecewise Eckart (piecewise Poeschl-Teller), and
+developing an analytic ``quantization condition'' for the highly-damped
+quasi-normal frequencies. We find that the (offset) + i n(gap) behaviour is
+common but not universal, with the controlling feature being whether or not the
+ratio of the surface gravities is a rational number. We furthermore observed
+that the relation between rational ratios of surface gravities and periodicity
+of QNFs is very generic, and also occurs within different analytic approaches
+applied to various types of black hole spacetimes. These observations are of
+direct relevance to any physical situation where highly-damped quasi-normal
+modes are important.",1011.4634v1
+2011-03-08,Application of Explicit Symplectic Algorithms to Integration of Damping Oscillators,"In this paper an approach is outlined. With this approach some explicit
+algorithms can be applied to solve the initial value problem of $n-$dimensional
+damped oscillators. This approach is based upon following structure: for any
+non-conservative classical mechanical system and arbitrary initial conditions,
+there exists a conservative system; both systems share one and only one common
+phase curve; and, the value of the Hamiltonian of the conservative system is,
+up to an additive constant, equal to the total energy of the non-conservative
+system on the aforementioned phase curve, the constant depending on the initial
+conditions. A key way applying explicit symplectic algorithms to damping
+oscillators is that by the Newton-Laplace principle the nonconservative force
+can be reasonably assumed to be equal to a function of a component of
+generalized coordinates $q_i$ along a phase curve, such that the damping force
+can be represented as a function analogous to an elastic restoring force
+numerically in advance. Two numerical examples are given to demonstrate the
+good characteristics of the algorithms.",1103.1455v1
+2011-03-09,Nonlinear damping in mechanical resonators based on graphene and carbon nanotubes,"Carbon nanotubes and graphene allow fabricating outstanding nanomechanical
+resonators. They hold promise for various scientific and technological
+applications, including sensing of mass, force, and charge, as well as the
+study of quantum phenomena at the mesoscopic scale. Here, we have discovered
+that the dynamics of nanotube and graphene resonators is in fact highly exotic.
+We propose an unprecedented scenario where mechanical dissipation is entirely
+determined by nonlinear damping. As a striking consequence, the quality factor
+Q strongly depends on the amplitude of the motion. This scenario is radically
+different from that of other resonators, whose dissipation is dominated by a
+linear damping term. We believe that the difference stems from the reduced
+dimensionality of carbon nanotubes and graphene. Besides, we exploit the
+nonlinear nature of the damping to improve the figure of merit of
+nanotube/graphene resonators.",1103.1788v1
+2011-05-03,Entanglement in a Bipartite Gaussian State,"To examine the loss of entanglement in a two-particle Gaussian system, we
+couple it to an environment and use the Non-Rotating Wave master equation to
+study the system's dynamics. We also present a derivation of this equation. We
+consider two different types of evolution. Under free evolution we find that
+entanglement is lost quickly between the particles. When a harmonic potential
+is added between the particles, two very different behaviours can be observed,
+namely in the over and under-damped cases respectively, where the strength of
+the damping is determined by how large the coupling to the bath is with respect
+to the frequency of the potential. In the over-damped case, we find that the
+entanglement vanishes at even shorter times than it does in the free evolution.
+In the (very) under-damped case, we observe that the entanglement does not
+vanish. Instead it oscillates towards a stable value.",1105.0564v1
+2011-06-15,Plasma damping effects on the radiative energy loss of relativistic particles,"The energy loss of a relativistic charge undergoing multiple scatterings
+while traversing an infinite, polarizable and absorptive plasma is
+investigated. Polarization and damping mechanisms in the medium are
+phenomenologically modelled by a complex index of refraction. Apart from the
+known Ter-Mikaelian effect related to the dielectric polarization of matter, we
+find an additional, substantial reduction of the energy loss due to damping of
+radiation. The observed effect is more prominent for larger damping and/or
+larger energy of the charge. A conceivable analog of this phenomenon in QCD
+could influence the study of jet quenching phenomena in ultra-relativistic
+heavy-ion collisions at RHIC and LHC.",1106.2856v3
+2011-09-12,Reduction of compressibility and parallel transfer by Landau damping in turbulent magnetized plasmas,"Three-dimensional numerical simulations of decaying turbulence in a
+magnetized plasma are performed using a so-called FLR-Landau fluid model which
+incorporates linear Landau damping and finite Larmor radius (FLR) corrections.
+It is shown that compared to simulations of compressible Hall-MHD, linear
+Landau damping is responsible for significant damping of magnetosonic waves,
+which is consistent with the linear kinetic theory. Compressibility of the
+fluid and parallel energy cascade along the ambient magnetic field are also
+significantly inhibited when the beta parameter is not too small. In contrast
+with Hall-MHD, the FLR-Landau fluid model can therefore correctly describe
+turbulence in collisionless plasmas such as the solar wind, providing an
+interpretation for its nearly incompressible behavior.",1109.2636v1
+2011-09-24,Existence of weak solutions for the generalized Navier-Stokes equations with damping,"In this work we consider the generalized Navier-Stoke equations with the
+presence of a damping term in the momentum equation. % The problem studied here
+derives from the set of equations which govern the isothermal flow of
+incompressible, homogeneous and non-Newtonian fluids. % For the generalized
+Navier-Stokes problem with damping, we prove the existence of weak solutions by
+using regularization techniques, the theory of monotone operators and
+compactness arguments together with the local decomposition of the pressure and
+the Lipschitz-truncation method. The existence result proved here holds for any
+$q>\frac{2N}{N+2}$ and any $\sigma>1$, where $q$ is the exponent of the
+diffusion term and $\sigma$ is the exponent which characterizes the damping
+term.",1109.5217v1
+2011-11-14,New Electrodynamics of Pulsars,"We have recently proposed that Force-Free Electrodynamics (FFE) does not
+apply to pulsars -- pulsars should be described by the high-conductivity limit
+of Strong-Field Electrodynamics (SFE), which predicts an order-unity damping of
+the Poynting flux, while FFE postulates zero damping. The strong damping result
+has not been accepted by several pulsar experts, who claim that FFE basically
+works and the Poynting flux damping can be arbitrarily small.
+  Here we consider a thought experiment -- cylindrical periodic pulsar. We show
+that FFE is incapable of describing this object, while SFE predictions are
+physically plausible. The intrinsic breakdown of FFE should mean that the FFE
+description of the singular current layer (the only region of magnetosphere
+where FFE and the high-conductivity SFE differ) is incorrect. Then the
+high-conductivity SFE should be the right theory for real pulsars too, and the
+pure-FFE description of pulsars should be discarded.",1111.3377v1
+2011-12-20,Dynamics of DNA breathing in the Peyrard-Bishop model with damping and external force,"The impact of damping effect and external forces to the DNA breathing is
+investigated within the Peyrard-Bishop model. In in the continuum limit, the
+dynamics of the breathing of DNA is described by the forced-damped nonlinear
+Schrodinger equation and studied by means of variational method. The analytical
+solutions are obtained for special cases. It is shown that the breather
+propagation is decelerated in the presence of damping factor without the
+external force, while the envelope velocity and the amplitude increase
+significantly with the presence of external force. It is particularly found
+that the higher harmonic terms are enhanced when the periodic force is applied.
+It is finally argued that the external force accelerates the DNA breathing.",1112.4715v1
+2012-02-22,Radiation Damping in the Photoionization of Fe^{14+},"A theoretical investigation of photoabsorption and photoionization of
+Fe^{14+} extending beyond an earlier frame transformation R-matrix
+implementation is performed using a fully-correlated, Breit-Pauli R-matrix
+formulation including both fine-structure splitting of strongly-bound
+resonances and radiation damping. The radiation damping of $2p\rightarrow nd$
+resonances gives rise to a resonant photoionization cross section that is
+significantly lower than the total photoabsorption cross section. Furthermore,
+the radiation-damped photoionization cross section is found to be in good
+agreement with recent experimental results once a global shift in energy of
+$\approx -3.5$ eV is applied. These findings have important implications.
+Firstly, the presently available synchrotron experimental data are applicable
+only to photoionization processes and not to photoabsorption; the latter is
+required in opacity calculations. Secondly, our computed cross section, for
+which the L-shell ionization threshold is aligned with the NIST value, shows a
+series of $2p \rightarrow nd$ Rydberg resonances that are uniformly 3-4 eV
+higher in energy than the corresponding experimental profiles, indicating that
+the L-shell threshold energy values currently recommended by NIST are likely in
+error.",1202.4800v1
+2012-02-29,Present status of development of damping ring extraction kicker system for CLIC,"The CLIC damping rings will produce ultra-low emittance beam, with high bunch
+charge, necessary for the luminosity performance of the collider. To limit the
+beam emittance blow-up due to oscillations, the pulse power modulators for the
+damping ring kickers must provide extremely flat, high-voltage pulses:
+specifications call for a 160 ns duration and a flattop of 12.5 kV, 250 A, with
+a combined ripple and droop of not more than \pm0.02 %. The stripline design is
+also extremely challenging: the field for the damping ring kicker system must
+be homogenous to within \pm0.01 % over a 1 mm radius, and low beam coupling
+impedance is required. The solid-state modulator, the inductive adder, is a
+very promising approach to meeting the demanding specifications for the field
+pulse ripple and droop. This paper describes the initial design of the
+inductive adder and the striplines of the kicker system.",1202.6527v1
+2012-04-03,Inhomogeneity of the phase space of the damped harmonic oscillator under Levy noise,"The damped harmonic oscillator under symmetric L\'{e}vy white noise shows
+inhomogeneous phase space, which is in contrast to the homogeneous one of the
+same oscillator under the Gaussian white noise, as shown in a recent paper [I.
+M. Sokolov, W. Ebeling, and B. Dybiec, Phys. Rev. E \textbf{83}, 041118
+(2011)]. The inhomogeneity of the phase space shows certain correlation between
+the coordinate and the velocity of the damped oscillator under symmetric
+L\'{e}vy white noise. In the present work we further explore the physical
+origin of these distinguished features and find that it is due to the
+combination of the damped effect and heavy tail of the noise. We demonstrate
+directly this in the reduced coordinate $\tilde{x}$ versus velocity $\tilde{v}$
+plots and identify the physics of the anti-association of the coordinate and
+velocity.",1204.0593v2
+2012-06-20,Metadamping: An emergent phenomenon in dissipative metamaterials,"We theoretically demonstrate the concept of metadamping in dissipative
+metamaterials. We consider an infinite mass-spring chain with repeated local
+resonators and a statically equivalent periodic chain whose wave propagation
+characteristics are based on Bragg scattering. For each system we introduce
+identical viscous damping (dashpot) elements and compare the damping ratio
+associated with all Bloch modes. We find that the locally resonant metamaterial
+exhibits higher dissipation overall which indicates a damping emergence
+phenomena due to the presence of local resonance. We conclude our investigation
+by quantifying the degree of emergent damping as a function of the long-wave
+speed of sound in the medium or the static stiffness.",1206.4577v2
+2012-07-12,Spin Damping in an RF Atomic Magnetometer,"Under negative feedback, the quality factor Q of a radio-frequency
+magnetometer can be decreased by more than two orders of magnitude, so that any
+initial perturbation of the polarized spin system can be rapidly damped,
+preparing the magnetometer for detection of the desired signal. We find that
+noise is also suppressed under such spin-damping, with a characteristic
+spectral response corresponding to the type of noise; therefore magnetic,
+photon-shot, and spin-projection noise can be measured distinctly. While the
+suppression of resonant photon-shot noise implies the closed-loop production of
+polarization-squeezed light, the suppression of resonant spin-projection noise
+does not imply spin-squeezing, rather simply the broadening of the noise
+spectrum with Q. Furthermore, the application of spin-damping during
+phase-sensitive detection suppresses both signal and noise in such a way as to
+increase the sensitivity bandwidth. We demonstrate a three-fold increase in the
+magnetometer's bandwidth while maintaining 0.3 fT/\surdHz sensitivity.",1207.2842v1
+2012-08-27,The properties of non-thermal X-ray filaments in young supernova remnants,"Context. Young supernova remnants (SNRs) exhibit narrow filaments of
+non-thermal X-ray emission whose widths can be limited either by electron
+energy losses or damping of the magnetic field. Aims. We want to investigate
+whether or not different models of these filaments can be observationally
+tested. Methods. Using observational parameters of four historical remnants, we
+calculate the filament profiles and compare the spectra of the filaments with
+those of the total non-thermal emission. For that purpose, we solve an
+one-dimensional stationary transport equation for the isotropic differential
+number density of the electrons. Results. We find that the difference between
+the spectra of filament and total non-thermal emission above 1 keV is more
+pronounced in the damping model than in the energy-loss model. Conclusions. A
+considerable damping of the magnetic field can result in an observable
+difference between the spectra of filament and total non-thermal emission, thus
+potentially permitting an observational discrimination between the energy-loss
+model and the damping model of the X-ray filaments.",1208.5322v1
+2012-09-10,Mid-infrared plasmons in scaled graphene nanostructures,"Plasmonics takes advantage of the collective response of electrons to
+electromagnetic waves, enabling dramatic scaling of optical devices beyond the
+diffraction limit. Here, we demonstrate the mid-infrared (4 to 15 microns)
+plasmons in deeply scaled graphene nanostructures down to 50 nm, more than 100
+times smaller than the on-resonance light wavelength in free space. We reveal,
+for the first time, the crucial damping channels of graphene plasmons via its
+intrinsic optical phonons and scattering from the edges. A plasmon lifetime of
+20 femto-seconds and smaller is observed, when damping through the emission of
+an optical phonon is allowed. Furthermore, the surface polar phonons in SiO2
+substrate underneath the graphene nanostructures lead to a significantly
+modified plasmon dispersion and damping, in contrast to a non-polar
+diamond-like-carbon (DLC) substrate. Much reduced damping is realized when the
+plasmon resonance frequencies are close to the polar phonon frequencies. Our
+study paves the way for applications of graphene in plasmonic waveguides,
+modulators and detectors in an unprecedentedly broad wavelength range from
+sub-terahertz to mid-infrared.",1209.1984v1
+2012-11-05,No asymptotically highly damped quasi-normal modes without horizons?,"We explore the question of what happens with the asymptotically highly damped
+quasi-normal modes ($\ell$ fixed, $|\omega_{I}|\to\infty$) when the underlying
+spacetime has no event horizons. We consider the characteristic oscillations of
+a scalar field in a large class of asymptotically flat spherically symmetric
+static spacetimes without (absolute) horizons, such that the class accommodates
+the cases that are known to be of some sort of physical interest. The question
+of the asymptotic quasi-normal modes in such spacetimes is relevant to
+elucidate the connection between the behavior of the asymptotic quasi-normal
+modes and the quantum properties of event horizons, as put forward in some
+recent important conjectures. We prove for a large class of asymptotically flat
+spacetimes without horizons that the scalar field asymptotically highly damped
+modes do not exist. This provides in our view additional evidence that there is
+indeed a close link between the asymptotically highly damped modes and the
+existence of spacetime horizons (and their properties).",1211.1046v2
+2012-11-21,Chaotic saddles in nonlinear modulational interactions in a plasma,"A nonlinear model of modulational processes in the subsonic regime involving
+a linearly unstable wave and two linearly damped waves with different damping
+rates in a plasma is studied numerically. We compute the maximum Lyapunov
+exponent as a function of the damping rates in a two-parameter space, and
+identify shrimp-shaped self-similar structures in the parameter space. By
+varying the damping rate of the low-frequency wave, we construct bifurcation
+diagrams and focus on a saddle-node bifurcation and an interior crisis
+associated with a periodic window. We detect chaotic saddles and their stable
+and unstable manifolds, and demonstrate how the connection between two chaotic
+saddles via coupling unstable periodic orbits can result in a crisis-induced
+intermittency. The relevance of this work for the understanding of modulational
+processes observed in plasmas and fluids is discussed.",1211.5070v1
+2012-12-18,Thermal activation at moderate-to-high and high damping: finite barrier effects and force spectroscopy,"We study the thermal escape problem in the moderate-to-high and high damping
+regime of a system with a parabolic barrier. We present a formula that matches
+our numerical results accounting for finite barrier effects, and compare it
+with previous works. We also show results for the full damping range. We
+quantitatively study some aspects on the relation between mean first passage
+time and the definition of a escape rate. To finish we apply our results and
+considerations in the framework of force spectroscopy problems. We study the
+differences on the predictions using the different theories and discuss the
+role of $\gamma \dot{F}$ as the relevant parameter at high damping.",1212.4290v2
+2013-01-18,Interfacial roughening in non-ideal fluids: Dynamic scaling in the weak- and strong-damping regime,"Interfacial roughening denotes the nonequilibrium process by which an
+initially flat interface reaches its equilibrium state, characterized by the
+presence of thermally excited capillary waves. Roughening of fluid interfaces
+has been first analyzed by Flekkoy and Rothman [Phys. Rev. Lett. 75, 260
+(1995)], where the dynamic scaling exponents in the weakly damped case in two
+dimensions were found to agree with the Kardar-Parisi-Zhang universality class.
+We extend this work by taking into account also the strong-damping regime and
+perform extensive fluctuating hydrodynamics simulations in two dimensions using
+the Lattice Boltzmann method. We show that the dynamic scaling behavior is
+different in the weakly and strongly damped case.",1301.4468v2
+2013-02-02,Achieving the Quantum Ground State of a Mechanical Oscillator using a Bose-Einstein Condensate with Back-Action and Cold Damping feedback schemes,"We present a detailed study to show the possibility of approaching the
+quantum ground-state of a hybrid optomechanical quantum device formed by a
+Bose-Einstein condensate (BEC) confined inside a high-finesse optical cavity
+with an oscillatory end mirror. Cooling is achieved using two experimentally
+realizable schemes: back-action cooling and cold damping quantum feedback
+cooling. In both the schemes, we found that increasing the two body atom-atom
+interaction brings the mechanical oscillator to its quantum ground state. It
+has been observed that back-action cooling is more effective in the good cavity
+limit while the cold damping cooling scheme is more relevant in the bad cavity
+limit. It is also shown that in the cold damping scheme, the device is more
+efficient in the presence of BEC than in the absence of BEC.",1302.0339v1
+2013-02-27,Resonantly damped oscillations of elliptically shaped stratified emerging coronal loops,"The effects of both elliptical shape and stage of emergence of the coronal
+loop on the resonant absorption of standing kink oscillations are studied. To
+do so, a typical coronal loop is modeled as a zero-beta longitudinally
+stratified cylindrical magnetic flux tube. We developed the connection formulae
+for the resonant absorption of standing transversal oscillations of a coronal
+loop with an elliptical shape, at various stages of its emergence. Using the
+connection formulae, the dispersion relation is derived and solved numerically
+to obtain the frequencies and damping rates of the fundamental and
+first-overtone kink modes. Our numerical results show that both the elliptical
+shape and stage of emergence of the loop alter the frequencies and damping
+rates of the tube as well as the ratio of frequencies of the fundamental and
+its first-overtone modes. However, the ratio of the oscillation frequency to
+the damping rate is not affected by the tube shape and stage of its emergence
+and also is independent of the density stratification parameter.",1302.6884v1
+2013-02-28,Damping of Quantum Vibrations Revealed in Deep Sub-barrier Fusion,"We demonstrate that when two colliding nuclei approach each other, their
+quantum vibrations are damped near the touching point. We show that this
+damping is responsible for the fusion hindrance phenomena measured in the deep
+sub-barrier fusion reactions. To show those, we for the first time apply the
+random-phase-approximation (RPA) method to the two-body $^{16}$O + $^{16}$O and
+$^{40}$Ca + $^{40}$Ca systems. We calculate the octupole transition strengths
+for the two nuclei adiabatically approaching each other. The calculated
+transition strength drastically decreases near the touching point, strongly
+suggesting the vanishing of the quantum couplings between the relative motion
+and the vibrational intrinsic degrees of freedom of each nucleus. Based on this
+picture, we also calculate the fusion cross section for the $^{40}$Ca +
+$^{40}$Ca system using the coupled-channel method with the damping factor
+simulating the vanishing of the couplings. The calculated results reproduce
+well the experimental data, indicating that the smooth transition from the
+sudden to adiabatic processes indeed occurs in the deep sub-barrier fusion
+reactions.",1302.7115v2
+2013-03-14,Microwave-assisted switching of a nanomagnet: analytical determination of the optimal microwave field,"We analytically determine the optimal microwave field that allows for the
+magnetization reversal of a nanomagnet modeled as a macrospin. This is done by
+minimizing the total injected energy. The results are in good agreement with
+the fields obtained numerically using the optimal control theory. For typical
+values of the damping parameter, a weak microwave field is sufficient to induce
+switching through a resonant process. The optimal field is orthogonal to the
+magnetization direction at any time and modulated both in amplitude and
+frequency. The dependence of the pulse shape on the applied field and damping
+parameter is interpreted. The total injected energy is found to be
+proportionnal to the energy barrier between the initial state and the saddle
+point and to the damping parameter. This result may be used as a means for
+probing the damping parameter in real nanoparticles.",1303.3501v4
+2013-04-05,Nonlocal Gravity: Damping of Linearized Gravitational Waves,"In nonlocal general relativity, linearized gravitational waves are damped as
+they propagate from the source to the receiver in the Minkowski vacuum.
+Nonlocal gravity is a generalization of Einstein's theory of gravitation in
+which nonlocality is due to the gravitational memory of past events. That
+nonlocal gravity is dissipative is demonstrated in this paper within certain
+approximation schemes. The gravitational memory drag leads to the decay of the
+amplitude of gravitational waves given by the exponential damping factor exp
+(-t/\tau), where $\tau$ depends on the kernel of nonlocal gravity. The damping
+time $\tau$ is estimated for gravitational waves of current observational
+interest and is found to be of the order of, or longer than, the age of the
+universe.",1304.1769v1
+2013-07-29,Damping of Primordial Gravitational Waves from Generalized Sources,"It has been shown that a cosmological background with an anisotropic stress
+tensor, appropriate for a free streaming thermal neutrino background, can damp
+primordial gravitational waves after they enter the horizon, and can thus
+affect the CMB B-mode polarization signature due to such tensor modes. Here we
+generalize this result, and examine the sensitivity of this effect to non-zero
+neutrino masses, extra neutrino species, and also a possible relativistic
+background of axions from axion strings. In particular, additional neutrinos
+with cosmologically interesting neutrino masses at the O(1) eV level will
+noticeably reduce damping compared to massless neutrinos for gravitational wave
+modes with $k\tau_0 \approx 100-200$, where $\tau_0 \approx 2/H_0$ and $H_0$ is
+the present Hubble parameter, while an axion background would produce a
+phase-dependent damping distinct from that produced by neutrinos.",1307.7571v1
+2013-08-08,Small global solutions to the damped two-dimensional Boussinesq equations,"The two-dimensional (2D) incompressible Euler equations have been thoroughly
+investigated and the resolution of the global (in time) existence and
+uniqueness issue is currently in a satisfactory status. In contrast, the global
+regularity problem concerning the 2D inviscid Boussinesq equations remains
+widely open. In an attempt to understand this problem, we examine the damped 2D
+Boussinesq equations and study how damping affects the regularity of solutions.
+Since the damping effect is insufficient in overcoming the difficulty due to
+the ""vortex stretching"", we seek unique global small solutions and the efforts
+have been mainly devoted to minimizing the smallness assumption. By positioning
+the solutions in a suitable functional setting (more precisely the homogeneous
+Besov space $\mathring{B}^1_{\infty,1}$), we are able to obtain a unique global
+solution under a minimal smallness assumption.",1308.1723v1
+2013-08-21,Approximate quantum error correction for generalized amplitude damping errors,"We present analytic estimates of the performances of various approximate
+quantum error correction schemes for the generalized amplitude damping (GAD)
+qubit channel. Specifically, we consider both stabilizer and nonadditive
+quantum codes. The performance of such error-correcting schemes is quantified
+by means of the entanglement fidelity as a function of the damping probability
+and the non-zero environmental temperature. The recovery scheme employed
+throughout our work applies, in principle, to arbitrary quantum codes and is
+the analogue of the perfect Knill-Laflamme recovery scheme adapted to the
+approximate quantum error correction framework for the GAD error model. We also
+analytically recover and/or clarify some previously known numerical results in
+the limiting case of vanishing temperature of the environment, the well-known
+traditional amplitude damping channel. In addition, our study suggests that
+degenerate stabilizer codes and self-complementary nonadditive codes are
+especially suitable for the error correction of the GAD noise model. Finally,
+comparing the properly normalized entanglement fidelities of the best
+performant stabilizer and nonadditive codes characterized by the same length,
+we show that nonadditive codes outperform stabilizer codes not only in terms of
+encoded dimension but also in terms of entanglement fidelity.",1308.4582v2
+2013-11-01,Kinetic theory of acoustic-like modes in nonextensive pair plasmas,"The low-frequency acoustic-like modes in a pair plasma (electron-positron or
+pair-ion) is studied by employing a kinetic theory model based on the Vlasov
+and Poisson's equation with emphasizing the Tsallis's nonextensive statistics.
+The possibility of the acoustic-like modes and their properties in both fully
+symmetric and temperature-asymmetric cases are examined by studying the
+dispersion relation, Landau damping and instability of modes. The resultant
+dispersion relation in this study is compatible with the acoustic branch of the
+experimental data [W. Oohara, D. Date, and R. Hatakeyama, Phys. Rev. Lett. 95,
+175003 (2005)], in which the electrostatic waves have been examined in a pure
+pair-ion plasma. Particularly, our study reveals that the occurrence of growing
+or damped acoustic-like modes depends strongly on the nonextensivity of the
+system as a measure for describing the long-range Coulombic interactions and
+correlations in the plasma. The mechanism that leads to the unstable modes lies
+in the heart of the nonextensive formalism yet, the mechanism of damping is the
+same developed by Landau. Furthermore, the solutions of acoustic-like waves in
+an equilibrium Maxwellian pair plasma are recovered in the extensive limit
+($q\rightarrow1$), where the acoustic modes have only the Landau damping and no
+growth.",1311.0193v1
+2013-11-29,Exploring viscous damping in undergraduate Physics laboratory using electromagnetically coupled oscillators,"We design a low-cost, electromagnetically coupled, simple harmonic oscillator
+and demonstrate free, damped and forced oscillations in an under-graduate (UG)
+Physics laboratory. It consists of a spring-magnet system that can oscillate
+inside a cylinder around which copper coils are wound. Such demonstrations can
+compliment the traditional way in which a Waves & Oscillations course is taught
+and offers a richer pedagogical experience for students. We also show that with
+minimal modifications, it can be used to probe the magnitude of viscous damping
+forces in liquids by analyzing the oscillations of an immersed magnet. Finally,
+we propose some student activities to explore non-linear damping effects and
+their characterization using this apparatus.",1311.7489v1
+2013-12-18,Radiative damping and synchronization in a graphene-based terahertz emitter,"We investigate the collective electron dynamics in a recently proposed
+graphene-based terahertz emitter under the influence of the radiative damping
+effect, which is included self-consistently in a molecular dynamics approach.
+We show that under appropriate conditions synchronization of the dynamics of
+single electrons takes place, leading to a rise of the oscillating component of
+the charge current. The synchronization time depends dramatically on the
+applied dc electric field and electron scattering rate, and is roughly
+inversely proportional to the radiative damping rate that is determined by the
+carrier concentration and the geometrical parameters of the device. The
+emission spectra in the synchronized state, determined by the oscillating
+current component, are analyzed. The effective generation of higher harmonics
+for large values of the radiative damping strength is demonstrated.",1312.5193v1
+2014-01-20,Analysis of mean cluster size in directed compact percolation near a damp wall,"We investigate the behaviour of the mean size of directed compact percolation
+clusters near a damp wall in the low-density region, where sites in the bulk
+are wet (occupied) with probability $p$ while sites on the wall are wet with
+probability $p_w$. Methods used to find the exact solution for the dry case
+($p_w=0$) and the wet case ($p_w=1$) turn out to be inadequate for the damp
+case. Instead we use a series expansion for the $p_w=2p$ case to obtain a
+second order inhomogeneous differential equation satisfied by the mean size,
+which exhibits a critical exponent $\gamma=2$, in common with the wet wall
+result. For the more general case of $p_w=rp$, with $r$ rational, we use a
+modular arithmetic method of finding ODEs and obtain a fourth order homogeneous
+ODE satisfied by the series. The ODE is expressed exactly in terms of $r$. We
+find that in the damp region $0<r<2$ the critical exponent $\gamma^{\rm
+damp}=1$, in common with the dry wall result.",1401.4793v1
+2014-02-13,On the Convergence of Approximate Message Passing with Arbitrary Matrices,"Approximate message passing (AMP) methods and their variants have attracted
+considerable recent attention for the problem of estimating a random vector
+$\mathbf{x}$ observed through a linear transform $\mathbf{A}$. In the case of
+large i.i.d. zero-mean Gaussian $\mathbf{A}$, the methods exhibit fast
+convergence with precise analytic characterizations on the algorithm behavior.
+However, the convergence of AMP under general transforms $\mathbf{A}$ is not
+fully understood. In this paper, we provide sufficient conditions for the
+convergence of a damped version of the generalized AMP (GAMP) algorithm in the
+case of quadratic cost functions (i.e., Gaussian likelihood and prior). It is
+shown that, with sufficient damping, the algorithm is guaranteed to converge,
+although the amount of damping grows with peak-to-average ratio of the squared
+singular values of the transforms $\mathbf{A}$. This result explains the good
+performance of AMP on i.i.d. Gaussian transforms $\mathbf{A}$, but also their
+difficulties with ill-conditioned or non-zero-mean transforms $\mathbf{A}$. A
+related sufficient condition is then derived for the local stability of the
+damped GAMP method under general cost functions, assuming certain strict
+convexity conditions.",1402.3210v3
+2014-03-28,Strichartz estimates and smooth attractors for a sub-quintic wave equation with fractional damping in bounded domains,"The work is devoted to Dirichlet problem for sub-quintic semi-linear wave
+equation with damping damping term of the form $(-\Delta)^\alpha\partial_t u$,
+$\alpha\in(0,\frac{1}{2})$, in bounded smooth domains of $\Bbb R^3$. It appears
+that to prove well-posedness and develop smooth attractor theory for the
+problem we need additional regularity of the solutions, which does not follow
+from the energy estimate. Considering the original problem as perturbation of
+the linear one the task is reduced to derivation of Strichartz type estimate
+for the linear wave equation with fractional damping, which is the main feature
+of the work. Existence of smooth exponential attractor for the natural
+dynamical system associated with the problem is also established.",1403.7476v1
+2014-05-12,Global Existence and Nonlinear Diffusion of Classical Solutions to Non-Isentropic Euler Equations with Damping in Bounded Domain,"We considered classical solutions to the initial boundary value problem for
+non-isentropic compressible Euler equations with damping in multi-dimensions.
+We obtained global a priori estimates and global existence results of classical
+solutions to both non-isentropic Euler equations with damping and their
+nonlinear diffusion equations under small data assumption. We proved the
+pressure and velocity decay exponentially to constants, while the entropy and
+density can not approach constants. Finally, we proved the pressure and
+velocity of the non-isentropic Euler equations with damping converge
+exponentially to those of their nonlinear diffusion equations when the time
+goes to infinity.",1405.2842v3
+2014-05-16,Damping of Confined Modes in a Ferromagnetic Thin Insulating Film: Angular Momentum Transfer Across a Nanoscale Field-defined Interface,"We observe a dependence of the damping of a confined mode of precessing
+ferromagnetic magnetization on the size of the mode. The micron-scale mode is
+created within an extended, unpatterned YIG film by means of the intense local
+dipolar field of a micromagnetic tip. We find that damping of the confined mode
+scales like the surface-to-volume ratio of the mode, indicating an interfacial
+damping effect (similar to spin pumping) due to the transfer of angular
+momentum from the confined mode to the spin sink of ferromagnetic material in
+the surrounding film. Though unexpected for insulating systems, the measured
+intralayer spin-mixing conductance $g_{\uparrow \downarrow} = 5.3 \times
+10^{19} {\rm m}^{-2}$ demonstrates efficient intralayer angular momentum
+transfer.",1405.4203v2
+2014-06-03,Persistently damped transport on a network of circles,"In this paper we address the exponential stability of a system of transport
+equations with intermittent damping on a network of $N \geq 2$ circles
+intersecting at a single point $O$. The $N$ equations are coupled through a
+linear mixing of their values at $O$, described by a matrix $M$. The activity
+of the intermittent damping is determined by persistently exciting signals, all
+belonging to a fixed class. The main result is that, under suitable hypotheses
+on $M$ and on the rationality of the ratios between the lengths of the circles,
+such a system is exponentially stable, uniformly with respect to the
+persistently exciting signals. The proof relies on an explicit formula for the
+solutions of this system, which allows one to track down the effects of the
+intermittent damping.",1406.0731v4
+2014-06-06,Damping of quasiparticles in a Bose-Einstein condensate coupled to an optical cavity,"We present a general theory for calculating the damping rate of elementary
+density wave excitations in a Bose-Einstein condensate strongly coupled to a
+single radiation field mode of an optical cavity. Thereby we give a detailed
+derivation of the huge resonant enhancement in the Beliaev damping of a density
+wave mode, predicted recently by K\'onya et al., Phys.~Rev.~A 89, 051601(R)
+(2014). The given density-wave mode constitutes the polariton-like soft mode of
+the self-organization phase transition. The resonant enhancement takes place,
+both in the normal and ordered phases, outside the critical region. We show
+that the large damping rate is accompanied by a significant frequency shift of
+this polariton mode. Going beyond the Born-Markov approximation and determining
+the poles of the retarded Green's function of the polariton, we reveal a strong
+coupling between the polariton and a collective mode in the phonon bath formed
+by the other density wave modes.",1406.1669v1
+2014-08-18,Kirchhoff equations with strong damping,"We consider Kirchhoff equations with strong damping, namely with a friction
+term which depends on a power of the ""elastic"" operator. We address local and
+global existence of solutions in two different regimes depending on the
+exponent in the friction term.
+  When the exponent is greater than 1/2, the dissipation prevails, and we
+obtain global existence in the energy space assuming only degenerate
+hyperbolicity and continuity of the nonlinear term. When the exponent is less
+than 1/2, we assume strict hyperbolicity and we consider a phase space
+depending on the continuity modulus of the nonlinear term and on the exponent
+in the damping. In this phase space we prove local existence, and global
+existence if initial data are small enough.
+  The regularity we assume both on initial data and on the nonlinear term is
+weaker than in the classical results for Kirchhoff equations with standard
+damping.
+  Proofs exploit some recent sharp results for the linearized equation and
+suitably defined interpolation spaces.",1408.3908v1
+2014-08-28,A convergent method for linear half-space kinetic equations,"We give a unified proof for the well-posedness of a class of linear
+half-space equations with general incoming data and construct a Galerkin method
+to numerically resolve this type of equations in a systematic way. Our main
+strategy in both analysis and numerics includes three steps: adding damping
+terms to the original half-space equation, using an inf-sup argument and
+even-odd decomposition to establish the well-posedness of the damped equation,
+and then recovering solutions to the original half-space equation. The proposed
+numerical methods for the damped equation is shown to be quasi-optimal and the
+numerical error of approximations to the original equation is controlled by
+that of the damped equation. This efficient solution to the half-space problem
+is useful for kinetic-fluid coupling simulations.",1408.6630v4
+2014-09-02,Damping effects in hole-doped graphene: the relaxation-time approximation,"The dynamical conductivity of interacting multiband electronic systems
+derived in Ref.[1] is shown to be consistent with the general form of the Ward
+identity. Using the semiphenomenological form of this conductivity formula, we
+have demonstrated that the relaxation-time approximation can be used to
+describe the damping effects in weakly interacting multiband systems only if
+local charge conservation in the system and gauge invariance of the response
+theory are properly treated. Such a gauge-invariant response theory is
+illustrated on the common tight-binding model for conduction electrons in
+hole-doped graphene. The model predicts two distinctly resolved maxima in the
+energy-loss-function spectra. The first one corresponds to the intraband
+plasmons (usually called the Dirac plasmons). On the other hand, the second
+maximum ($\pi$ plasmon structure) is simply a consequence of the van Hove
+singularity in the single-electron density of states. The dc resistivity and
+the real part of the dynamical conductivity are found to be well described by
+the relaxation-time approximation, but only in the parametric space in which
+the damping is dominated by the direct scattering processes. The ballistic
+transport and the damping of Dirac plasmons are thus the questions that require
+abandoning the relaxation-time approximation.",1409.0621v1
+2014-11-13,Maximal correlation between flavor entanglement and oscillation damping due to localization effects,"Localization effects and quantum decoherence driven by the mass-eigenstate
+wave packet propagation are shown to support a statistical correlation between
+quantum entanglement and damped oscillations in the scenario of three-flavor
+quantum mixing for neutrinos. Once the mass-eigenstates that support flavor
+oscillations are identified as three-{\em qubit} modes, a decoherence scale can
+be extracted from correlation quantifiers, namely the entanglement of formation
+and the logarithmic negativity. Such a decoherence scale is compared with the
+coherence length of damped oscillations. Damping signatures exhibited by flavor
+transition probabilities as an effective averaging of the oscillating terms are
+then explained as owing to loss of entanglement between mass modes involved in
+the relativistic propagation.",1411.3634v1
+2015-01-20,Damping of long wavelength collective modes in spinor Bose-Fermi mixtures,"Using an effective field theory we describe the low energy bosonic
+excitations in a three dimensional ultra-cold mixture of spin-1 bosons and
+spin-1/2 fermions. We establish an interesting fermionic excitation induced
+generic damping of the usual undamped long wavelength bosonic collective
+Goldstone modes. Two states with bosons forming either a ferromagnetic or polar
+superfluid are studied. The linear dispersion of the bosonic Bogoliubov
+excitations is preserved with a renormalized sound velocity. For the polar
+superfluid we find both gapless modes (density and spin) are damped, whereas in
+the ferromagnetic superfluid we find the density (spin) mode is (not) damped.
+We argue quite generally that this holds for any mixture of bosons and fermions
+that are coupled through at least a density-density interaction. We discuss the
+implications of our many-body interaction results for experiments on Bose-Fermi
+mixtures.",1501.05015v2
+2015-01-27,Non-linear fluctuation effects in dynamics of freely suspended film,"Long-scale dynamic fluctuation phenomena in freely suspended films is
+analyzed. We consider isotropic films that, say, can be pulled from bulk
+smectic A liquid crystals. The key feature of such objects is possibility of
+bending deformations of the film. The bending (also known as flexular) mode
+turns out to be anomalously weakly attenuated. In the harmonic approximation
+there is no viscous-like damping of the bending mode, proportional to q^2 (q is
+the wave vector of the mode), since it is forbidden by the rotational symmetry.
+Therefore the bending mode is strongly affected by non-linear dynamic
+fluctuation effects. We calculate the dominant fluctuation contributions to the
+damping of the bending mode due to its coupling to the in-plane viscous mode,
+that restores the viscous-like q^2 damping of the bending mode. Our
+calculations are performed in the framework of the perturbation theory where
+the coupling of the modes is assumed to be small, then the bending mode damping
+is relatively weak. We discuss our results in the context of existing
+experiments and numeric simulations of the freely suspended films and propose
+possible experimental observations of our predictions.",1501.06703v1
+2015-01-30,Intrinsic Damping of Collective Spin Modes in a Two-Dimensional Fermi Liquid with Spin-Orbit Coupling,"A Fermi liquid with spin-orbit coupling (SOC) is expected to support a new
+kind of collective modes: oscillations of magnetization in the absence of the
+magnetic field. We show that these modes are damped by the electron-electron
+interaction even in the limit of an infinitely long wavelength (q = 0). The
+linewidth of the collective mode is on the order of {\Delta}^2=E_F , where
+{\Delta} is a characteristic spin-orbit energy splitting and E_F is the Fermi
+energy. Such damping is in a stark contrast to known damping mechanisms of both
+charge and spin collective modes in the absence of SOC, all of which disappear
+at q = 0, and arises because none of the components of total spin is conserved
+in the presence of SOC.",1502.00027v1
+2015-02-01,Nonlocal Damping of Helimagnets in One-Dimensional Interacting Electron Systems,"We investigate the magnetization relaxation of a one-dimensional helimagnetic
+system coupled to interacting itinerant electrons. The relaxation is assumed to
+result from the emission of plasmons, the elementary excitations of the
+one-dimensional interacting electron system, caused by slow changes of the
+magnetization profile. This dissipation mechanism leads to a highly nonlocal
+form of magnetization damping that is strongly dependent on the
+electron-electron interaction. Forward scattering processes lead to a spatially
+constant damping kernel, while backscattering processes produce a spatially
+oscillating contribution. Due to the nonlocal damping, the thermal fluctuations
+become spatially correlated over the entire system. We estimate the
+characteristic magnetization relaxation times for magnetic quantum wires and
+nuclear helimagnets.",1502.00268v2
+2015-07-21,Onboard Calibration Circuit for the Front-end Electronics of DAMPE BGO Calorimeter,"An onboard calibration circuit has been designed for the front-end
+electronics (FEE) of DAMPE BGO Calorimeter. It is mainly composed of a 12 bit
+DAC, an operation amplifier and an analog switch. Test results showed that a
+dynamic range of 0 ~ 30 pC with a precision of 5 fC was achieved, which meets
+the requirements of the front-end electronics. Furthermore, it is used to test
+the trigger function of the FEEs. The calibration circuit has been implemented
+and verified by all the environmental tests for both Qualification Model and
+Flight Model of DAMPE. The DAMPE satellite will be launched at the end of 2015
+and the calibration circuit will perform onboard calibration in space.",1507.05862v1
+2015-07-30,Reservoir interactions during Bose-Einstein condensation: modified critical scaling in the Kibble-Zurek mechanism of defect formation,"As a test of the Kibble-Zurek mechanism (KZM) of defect formation, we
+simulate the Bose-Einstein condensation transition in a toroidally confined
+Bose gas using the stochastic projected Gross-Pitaevskii equation (SPGPE), with
+and without the energy-damping reservoir interaction. Energy-damping alters the
+scaling of the winding number distribution with the quench time - a departure
+from the universal KZM theory that relies on equilibrium critical exponents.
+Numerical values are obtained for the correlation-length critical exponent
+$\nu$ and the dynamical critical exponent $z$ for each variant of reservoir
+interaction theory. The energy-damping reservoir interactions cause significant
+modification of the dynamical critical exponent of the phase transition, whilst
+preserving the essential KZM critical scaling behavior. Comparison of numerical
+and analytical two-point correlation functions further illustrates the effect
+of energy damping on the correlation length during freeze out.",1507.08357v1
+2015-08-23,Melnikov chaos in a modified Rayleigh-Duffing oscillator with $ φ^6$ potential,"The chaotic behavior of the modified Rayleigh-Duffing oscillator with $
+\phi^6$ potential and external excitation which modeles ship rolling motions
+are investigated both analytically and numerically. Melnikov method is applied
+and the conditions for the existence of homoclinic and heteroclinic chaos are
+obtained. The effects of nonlinear damping on roll motion of ships are analyzed
+in detail. As it is known, nonlinear roll damping is a very important parameter
+in estimating ship reponses. The predictions are tested numerical simulations
+based on the basin of attraction. We conclude that certains quadratic damping
+effects are contrary to cubic damping effect.",1508.05664v1
+2015-09-23,Quantum Error-Correcting Codes for Qudit Amplitude Damping,"Traditional quantum error-correcting codes are designed for the depolarizing
+channel modeled by generalized Pauli errors occurring with equal probability.
+Amplitude damping channels model, in general, the decay process of a multilevel
+atom or energy dissipation of a bosonic system at zero temperature. We discuss
+quantum error-correcting codes adapted to amplitude damping channels for higher
+dimensional systems (qudits). For multi-level atoms, we consider a natural kind
+of decay process, and for bosonic systems,we consider the qudit amplitude
+damping channel obtained by truncating the Fock basis of the bosonic modes to a
+certain maximum occupation number. We construct families of
+single-error-correcting quantum codes that can be used for both cases. Our
+codes have larger code dimensions than the previously known
+single-error-correcting codes of the same lengths. Additionally, we present
+families of multi-error correcting codes for these two channels, as well as
+generalizations of our construction technique to error-correcting codes for the
+qutrit $V$ and $\Lambda$ channels.",1509.06829v1
+2015-10-09,Determining form and data assimilation algorithm for weakly damped and driven Korteweg-de Vries equaton- Fourier modes case,"We show that the global attractor of a weakly damped and driven Korteweg-de
+Vries equation (KdV) is embedded in the long-time dynamics of an ordinary
+differential equation called a determining form. In particular, there is a
+one-to-one identification of the trajectories in the global attractor of the
+damped and driven KdV and the steady state solutions of the determining form.
+Moreover, we analyze a data assimilation algorithm (down-scaling) for the
+weakly damped and driven KdV. We show that given a certain number of low
+Fourier modes of a reference solution of the KdV equation, the algorithm
+recovers the full reference solution at an exponential rate in time.",1510.02730v1
+2015-10-27,Remarks on 1-D Euler Equations with Time-Decayed Damping,"We study the 1-d isentropic Euler equations with time-decayed damping
+\begin{equation} \left\{ \begin{aligned} &\partial_t \rho+\partial_x(\rho u)=0,
+\\ &\partial_t(\rho u)+ \partial_x(\rho
+u^2)+\partial_xp(\rho)=-\frac{\mu}{1+t}\rho u,\\
+&\rho|_{t=0}=1+\varepsilon\rho_0(x),u|_{t=0}=\varepsilon u_0(x). \end{aligned}
+\right. \nonumber \end{equation}
+  This work is inspired by a recent work of F. Hou, I. Witt and H.C. Yin
+\cite{Hou01}. In \cite{Hou01}, they proved a global existence and blow-up
+result of 3-d irrotational Euler flow with time-dependent damping. In the 1-d
+case, we will prove a different result when the damping decays of order $-1$
+with respect to the time $t$. More precisely, when $\mu>2$, we prove the global
+existence of the 1-d Euler system. While when $0\leq\mu\leq2 $, we will prove
+the blow up of $C^1$ solutions.",1510.08115v1
+2016-01-04,Generalized Bloch's theorem for viscous metamaterials: Dispersion and effective properties based on frequencies and wavenumbers that are simultaneously complex,"It is common for dispersion curves of damped periodic materials to be based
+on real frequencies versus complex wavenumbers or, conversely, real wavenumbers
+versus complex frequencies. The former condition corresponds to harmonic wave
+motion where a driving frequency is prescribed and where attenuation due to
+dissipation takes place only in space alongside spatial attenuation due to
+Bragg scattering. The latter condition, on the other hand, relates to free wave
+motion admitting attenuation due to energy loss only in time while spatial
+attenuation due to Bragg scattering also takes place. Here, we develop an
+algorithm for 1D systems that provides dispersion curves for damped free wave
+motion based on frequencies and wavenumbers that are permitted to be
+simultaneously complex. This represents a generalized application of Bloch's
+theorem and produces a dispersion band structure that fully describes all
+attenuation mechanisms, in space and in time. The algorithm is applied to a
+viscously damped mass-in-mass metamaterial exhibiting local resonance. A
+frequency-dependent effective mass for this damped infinite chain is also
+obtained.",1601.00683v1
+2016-02-05,Protecting entanglement from correlated amplitude damping channel using weak measurement and quantum measurement reversal,"Based on the quantum technique of weak measurement, we propose a scheme to
+protect the entanglement from correlated amplitude damping decoherence. In
+contrast to the results of memoryless amplitude damping channel, we show that
+the memory effects play a significant role in the suppression of entanglement
+sudden death and protection of entanglement under severe decoherence. Moreover,
+we find that the initial entanglement could be drastically amplified by the
+combination of weak measurement and quantum measurement reversal even under the
+correlated amplitude damping channel. The underlying mechanism can be
+attributed to the probabilistic nature of weak measurements.",1602.01998v1
+2016-03-10,Stability Analysis of Networked Systems Containing Damped and Undamped Nodes,"This paper answers the question if a qualitatively heterogeneous passive
+networked system containing damped and undamped nodes shows consensus in the
+output of the nodes in the long run. While a standard Lyapunov analysis shows
+that the damped nodes will always converge to a steady-state value, the
+convergence of the undamped nodes is much more delicate and depends on the
+parameter values of the network as well as on the topology of the graph. A
+complete stability analysis is presented based on an eigenvector analysis
+involving the mass values and the topology of both the original graph and the
+reduced graph obtained by a Kron reduction that eliminates the damped nodes.",1603.03477v1
+2016-05-02,Three types of nonlinear resonances,"We analyse different types of nonlinear resonances in a weakly damped Duffing
+oscillator using bifurcation theory techniques. In addition to (i) odd
+subharmonic resonances found on the primary branch of symmetric periodic
+solutions with the forcing frequency and (ii) even subharmonic resonances due
+to symmetry-broken periodic solutions that bifurcate off the primary branch and
+also oscillate at the forcing frequency, we uncover (iii) novel resonance type
+due to isolas of periodic solutions that are not connected to the primary
+branch. These occur between odd and even resonances, oscillate at a fraction of
+the forcing frequency, and give rise to a complicated resonance `curve' with
+disconnected elements and high degree of multistability. We use bifurcation
+continuation to compute resonance tongues in the plane of the forcing frequency
+vs. the forcing amplitude for different but fixed values of the damping rate.
+In this way, we demonstrate that identified here isolated resonances explain
+the intriguing structure of ""patchy tongues"" observed for week damping and link
+it to a seemingly unrelated phenomenon of ""bifurcation superstructure""
+described for moderate damping.",1605.00858v2
+2016-07-21,The Noisy Oscillator : Random Mass and Random Damping,"The problem of a linear damped noisy oscillator is treated in the presence of
+two multiplicative sources of noise which imply a random mass and random
+damping. The additive noise and the noise in the damping are responsible for an
+influx of energy to the oscillator and its dissipation to the surrounding
+environment. A random mass implies that the surrounding molecules not only
+collide with the oscillator but may also adhere to it, thereby changing its
+mass. We present general formulas for the first two moments and address the
+question of mean and energetic stabilities. The phenomenon of stochastic
+resonance, i.e. the expansion due to the noise of a system response to an
+external periodic signal, is considered for separate and joint action of two
+sources of noise and their characteristics.",1607.06289v2
+2016-08-09,Optomechanical damping of a nanomembrane inside an optical ring cavity,"We experimentally and theoretically investigate mechanical nanooscillators
+coupled to the light in an optical ring resonator made of dielectric mirrors.
+We identify an optomechanical damping mechanism that is fundamentally different
+to the well known cooling in standing wave cavities. While, in a standing wave
+cavity the mechanical oscillation shifts the resonance frequency of the cavity
+in a ring resonator the frequency does not change. Instead the position of the
+nodes is shifted with the mechanical excursion. We derive the damping rates and
+test the results experimentally with a silicon-nitride nanomembrane. It turns
+out that scattering from small imperfections of the dielectric mirror coatings
+has to be taken into account to explain the value of the measured damping rate.
+We extend our theoretical model and regard a second reflector in the cavity
+that captures the effects of mirror back scattering. This model can be used to
+also describe the situation of two membranes that both interact with the cavity
+fields. This may be interesting for future work on synchronization of distant
+oscillators that are coupled by intracavity light fields.",1608.02799v1
+2016-08-11,Decay of geodesic acoustic modes due to the combined action of phase mixing and Landau damping,"Geodesic acoustic modes (GAMs) are oscillations of the electric field whose
+importance in tokamak plasmas is due to their role in the regulation of
+turbulence. The linear collisionless damping of GAMs is investigated here by
+means of analytical theory and numerical simulations with the global
+gyrokinetic particle-in-cell code ORB5. The combined effect of the phase mixing
+and Landau damping is found to quickly redistribute the GAM energy in
+phase-space, due to the synergy of the finite orbit width of the passing ions
+and the cascade in wave number given by the phase mixing. When plasma
+parameters characteristic of realistic tokamak profiles are considered, the GAM
+decay time is found to be an order of magnitude lower than the decay due to the
+Landau damping alone, and in some cases of the same order of magnitude of the
+characteristic GAM drive time due to the nonlinear interaction with an ITG
+mode. In particular, the radial mode structure evolution in time is
+investigated here and reproduced quantitatively by means of a dedicated initial
+value code and diagnostics.",1608.03447v1
+2016-09-06,JRSP of three-particle state via three tripartite GHZ class in quantum noisy channels,"We present a scheme for joint remote state preparation (JRSP) of
+three-particle state via three tripartite Greenberger-Horne-Zeilinger (GHZ)
+entangled states as the quantum channel linking the parties. We use eight-qubit
+mutually orthogonal basis vector as measurement point of departure. The
+likelihood of success for this scheme has been found to be $1/8$. However, by
+putting some special cases into consideration, the chances can be ameliorated
+to $1/4$ and $1$. The effects of amplitude-damping noise, phase-damping noise
+and depolarizing noise on this scheme have been scrutinized and the analytical
+derivations of fidelities for the quantum noisy channels have been presented.
+We found that for $0.55\leq\eta\leq1$, the states conveyed through depolarizing
+channel lose more information than phase-damping channel while the information
+loss through amplitude damping channel is most minimal.",1609.01538v3
+2016-09-22,Damping of nonlinear standing kink oscillations: a numerical study,"We aim to study the standing fundamental kink mode of coronal loops in the
+nonlinear regime, investigating the changes in energy evolution in the
+cross-section and oscillation amplitude of the loop which are related to
+nonlinear effects, in particular to the development of the Kelvin-Helmholtz
+instability (KHI). We run idea, high-resolution three-dimensional (3D)
+magnetohydrodynamics (MHD) simulations, studying the influence of the initial
+velocity amplitude and the inhomogeneous layer thickness. We model the coronal
+loop as a straight, homogeneous magnetic flux tube with an outer inhomogeneous
+layer, embedded in a straight, homogeneous magnetic field. We find that, for
+low amplitudes which do not allow for the KHI to develop during the simulated
+time, the damping time agrees with the theory of resonant absorption. However,
+for higher amplitudes, the presence of KHI around the oscillating loop can
+alter the loop's evolution, resulting in a significantly faster damping than
+predicted by the linear theory in some cases. This questions the accuracy of
+seismological methods applied to observed damping profiles, based on linear
+theory.",1609.06883v1
+2016-09-28,Nonlinear damping and dephasing in nanomechanical systems,"We present a microscopic theory of nonlinear damping and dephasing of
+low-frequency eigenmodes in nano- and micro-mechanical systems. The mechanism
+of the both effects is scattering of thermally excited vibrational modes off
+the considered eigenmode. The scattering is accompanied by energy transfer of
+$2\hbar\omega_0$ for nonlinear damping and is quasieleastic for dephasing. We
+develop a formalism that allows studying both spatially uniform systems and
+systems with a strong nonuniformity, which is smooth on the typical wavelength
+of thermal modes but not their mean free path. The formalism accounts for the
+decay of thermal modes, which plays a major role in the nonlinear damping and
+dephasing. We identify the nonlinear analogs of the Landau-Rumer,
+thermoelastic, and Akhiezer mechanisms and find the dependence of the
+relaxation parameters on the temperature and the geometry of a system.",1609.08714v1
+2016-09-24,Parametric Landau damping of space charge modes,"Landau damping is the mechanism of plasma and beam stabilization; it arises
+through energy transfer from collective modes to the incoherent motion of
+resonant particles. Normally this resonance requires the resonant particle's
+frequency to match the collective mode frequency. We have identified an
+important new damping mechanism, {\it parametric Landau damping}, which is
+driven by the modulation of the mode-particle interaction. This reveals new
+possibilities for stability control through manipulation of both particle and
+mode-particle coupling spectra. We demonstrate the existence of parametric
+Landau damping in a simulation of transverse coherent modes of bunched
+accelerator beams with space charge.",1609.09393v3
+2016-12-13,Continuous-variable entanglement generated with a hybrid PT-symmetric system,"We study a proposal of generating macroscopic continuous-variable
+entanglement with two coupled waveguides respectively carrying optical damping
+and optical gain. Moreover, a squeezing element is added into one or both
+waveguides. We show that quantum noise effect existing in the process is
+essential to the degree of the generated entanglement. It will totally
+eliminate the entanglement in the setup of adding the squeezing element into
+the waveguide filled with optical damping material, but will not completely
+damp the entanglement to zero in the other configurations of having the
+squeezing element in the gain medium or in both gain and damping medium. The
+degree of the generated continuous-variable entanglement is irrelevant to the
+intensities of the input light in coherent states. Moreover, the relations
+between the entanglement and system parameters are illustrated in terms of the
+dynamical evolutions of the created continuous-variable entanglement.",1612.03996v2
+2017-01-08,Decentralized Robust Control for Damping Inter-area Oscillations in Power Systems,"As power systems become more and more interconnected, the inter-area
+oscillations has become a serious factor limiting large power transfer among
+different areas. Underdamped (Undamped) inter-area oscillations may cause
+system breakup and even lead to large-scale blackout. Traditional damping
+controllers include Power System Stabilizer (PSS) and Flexible AC Transmission
+System (FACTS) controller, which adds additional damping to the inter-area
+oscillation modes by affecting the real power in an indirect manner. However,
+the effectiveness of these controllers is restricted to the neighborhood of a
+prescribed set of operating conditions. In this paper, decentralized robust
+controllers are developed to improve the damping ratios of the inter-area
+oscillation modes by directly affecting the real power through the turbine
+governing system. The proposed control strategy requires only local signals and
+is robust to the variations in operation condition and system topology. The
+effectiveness of the proposed robust controllers is illustrated by detailed
+case studies on two different test systems.",1701.02036v1
+2017-01-18,Ion beam test results of the Plastic Scintillator Detector of DAMPE,"The DArk Matter Particle Explorer (DAMPE) is one of the four satellites
+within Strategic Pioneer Research Program in Space Science of the Chinese
+Academy of Science (CAS). DAMPE can detect electrons, photons and ions in a
+wide energy range (5 GeV to 10 TeV) and ions up to iron (100GeV to 100 TeV).
+Plastic Scintillator Detector (PSD) is one of the four payloads in DAMPE,
+providing e/{\gamma} separation and charge identification up to Iron. An ion
+beam test was carried out for the Qualification Model of PSD in CERN with
+40GeV/u Argon primary beams. The Birk's saturation and charge resolution of PSD
+were investigated.",1701.04947v2
+2017-01-18,DAMPE space mission: first data,"The DAMPE (DArk Matter Particle Explorer) satellite was launched on December
+17, 2015 and started its data taking operation a few days later.
+  DAMPE has a large geometric factor ($\sim~0.3\ m^2\ sr$) and provides good
+tracking, calorimetric and charge measurements for electrons, gammas rays and
+nuclei. This will allow precise measurement of cosmic ray spectra from tens of
+$GeV$ up to about $100\ TeV$. In particular, the energy region between $1-100\
+TeV$ will be explored with higher precision compared to previous experiments.
+The various subdetectors allow an efficient identification of the electron
+signal over the large (mainly proton-induced) background. As a result, the
+all-electron spectrum will be measured with excellent resolution from few $GeV$
+up to few $TeV$, thus giving the opportunity to identify possible contribution
+of nearby sources. A report on the mission goals and status is presented,
+together with the on-orbit detector performance and the first data coming from
+space.",1701.05046v1
+2017-01-25,Control Allocation for Wide Area Coordinated Damping,"In this work, a modal-based sparse control allocation (CA) is proposed for
+coordinated and fault-tolerant wide-area damping controllers (WADCs). In our
+proposed method, the supervisory CA only communicates with necessary actuators
+to achieve the required damping performance and in case of actuator failures
+(e.g., due to loss of communication or scheduling), capabilities of the
+remaining actuators are fully used before the nominal performance is degraded.
+This method offers the advantages of modular design where WADC is initially
+designed to achieve satisfactory damping without the detailed knowledge of
+actuators. In the next step, CA is designed to manage actuator failures and
+limitations without the need to redesign the nominal WADC. The proposed
+approach is applied to a modified $286$-bus Western Electricity Coordinating
+Council (WECC) system to verify the feasibility on a complex power system.
+Simulation results indicate the effectiveness of the proposed method in
+coordinating multiple actuators and building resiliency.",1701.07456v1
+2017-03-22,Direct Measurement of Kramers Turnover with a Levitated Nanoparticle,"Understanding the thermally activated escape from a metastable state is at
+the heart of important phenomena such as the folding dynamics of proteins, the
+kinetics of chemical reactions or the stability of mechanical systems. In 1940
+Kramers calculated escape rates both in the high damping and the low damping
+regime and suggested that the rate must have a maximum for intermediate
+damping. This phenomenon, today known as the Kramers turnover, has triggered
+important theoretical and numerical studies. However, to date there is no
+direct and quantitative experimental verification of this turnover. Using a
+nanoparticle trapped in a bi-stable optical potential we experimentally measure
+the nanoparticle's transition rates for variable damping and directly resolve
+the Kramers turnover. Our measurements are in agreement with an analytical
+model that is free of adjustable parameters.",1703.07699v2
+2017-04-03,Suppression of plasma echoes and Landau damping in Sobolev spaces by weak collisions in a Vlasov-Fokker-Planck equation,"In this paper, we study Landau damping in the weakly collisional limit of a
+Vlasov-Fokker-Planck equation with nonlinear collisions in the phase-space
+$(x,v) \in \mathbb T_x^n \times \mathbb R^n_v$. The goal is four-fold: (A) to
+understand how collisions suppress plasma echoes and enable Landau damping in
+agreement with linearized theory in Sobolev spaces, (B) to understand how phase
+mixing accelerates collisional relaxation, (C) to understand better how the
+plasma returns to global equilibrium during Landau damping, and (D) to rule out
+that collision-driven nonlinear instabilities dominate. We give an estimate for
+the scaling law between Knudsen number and the maximal size of the perturbation
+necessary for linear theory to be accurate in Sobolev regularity. We conjecture
+this scaling to be sharp (up to logarithmic corrections) due to potential
+nonlinear echoes in the collisionless model.",1704.00425v2
+2017-04-14,Impulse-Based Hybrid Motion Control,"The impulse-based discrete feedback control has been proposed in previous
+work for the second-order motion systems with damping uncertainties. The
+sate-dependent discrete impulse action takes place at zero crossing of one of
+both states, either relative position or velocity. In this paper, the proposed
+control method is extended to a general hybrid motion control form. We are
+using the paradigm of hybrid system modeling while explicitly specifying the
+state trajectories each time the continuous system state hits the guards that
+triggers impulsive control actions. The conditions for a stable convergence to
+zero equilibrium are derived in relation to the control parameters, while
+requiring only the upper bound of damping uncertainties to be known. Numerical
+examples are shown for an underdamped closed-loop dynamics with oscillating
+transients, an upper bounded time-varying positive system damping, and system
+with an additional Coulomb friction damping.",1704.04372v5
+2017-04-19,Reliable channel-adapted error correction: Bacon-Shor code recovery from amplitude damping,"We construct two simple error correction schemes adapted to amplitude damping
+noise for Bacon-Shor codes and investigate their prospects for fault-tolerant
+implementation. Both consist solely of Clifford gates and require far fewer
+qubits, relative to the standard method, to achieve correction to a desired
+order in the damping rate. The first, employing one-bit teleportation and
+single-qubit measurements, needs only one fourth as many physical qubits, while
+the second, using just stabilizer measurements and Pauli corrections, needs
+only half. We show that existing fault-tolerance methods can be employed for
+the latter, while the former can be made to avoid potential catastrophic errors
+and can easily cope with damping faults in ancilla qubits.",1704.05857v1
+2017-04-30,Comparison of dynamic mechanical properties of non-superheated and superheated A357 alloys,"The influence of superheat treatment on the microstructure and dynamic
+mechanical properties of A357 alloys has been investigated. The study of
+microstructure was performed by the optical microscope. Dynamic mechanical
+properties (storage modulus, loss modulus, and damping capacity) were measured
+by the dynamic mechanical analyzer (DMA). Microstructure showed coarser and
+angular eutectic Si particles with larger {\alpha}-Al dendrites in the
+non-superheated A357 alloy. In contrast, finer and rounded eutectic Si
+particles together with smaller and preferred oriented {\alpha}-Al dendrites
+have been observed in the superheated A357 alloy. Dynamic mechanical properties
+showed an increasing trend of loss modulus and damping capacity meanwhile a
+decreasing trend of storage modulus at elevated temperatures for superheated
+and non-superheated A357 alloys. The high damping capacity of superheated A357
+has been ascribed to the grain boundary damping at elevated temperatures.",1705.00350v1
+2017-05-19,Improving two - qubit state teleportation affected by amplitude damping noise based on choosing appropriate quantum channel,"We consider two qubit teleportation via quantum channel affected by amplitude
+damping noise. Addressing the same problem, X. Hu, Y. Gu, Q. Gong and G. Guo
+[Phys. Rev. A 81, 054302, (2010)] recently showed that in presence of noise,
+subjecting more qubits in quantum channel to amplitude damping can increase the
+fidelity of teleportation protocol. However, in this paper, by making some
+adjustments on quantum channel, we obtain teleportation fidelity which is even
+higher than one in the case of X. Hu et al. Moreover, our strategy is simpler
+than quantum distillation and compared to using weak measurement, it is
+deterministic. Furthermore, explicit analysis of fidelity is provided, we show
+that in general, choosing appropriate quantum channel enhances the ability of
+teleportation better and negates the fact that more amplitude damping noise
+more quality.",1705.07064v2
+2017-05-27,Charge reconstruction study of the DAMPE Silicon-Tungsten Tracker with ion beams,"The DArk Matter Particle Explorer (DAMPE) is one of the four satellites
+within Strategic Pioneer Research Program in Space Science of the Chinese
+Academy of Science (CAS). DAMPE can detect electrons, photons in a wide energy
+range (5 GeV to 10 TeV) and ions up to iron (100GeV to 100 TeV).
+Silicon-Tungsten Tracker (STK) is one of the four subdetectors in DAMPE,
+providing photon-electron conversion, track reconstruction and charge
+identification for ions. Ion beam test was carried out in CERN with 60GeV/u
+Lead primary beams. Charge reconstruction and charge resolution of STK
+detectors were investigated.",1705.09791v1
+2017-06-09,Effect of oxygen plasma on nanomechanical silicon nitride resonators,"Precise control of tensile stress and intrinsic damping is crucial for the
+optimal design of nanomechanical systems for sensor applications and quantum
+optomechanics in particular. In this letter we study the in uence of oxygen
+plasma on the tensile stress and intrinsic damping of nanomechanical silicon
+nitride resonators. Oxygen plasma treatments are common steps in micro and
+nanofabrication. We show that oxygen plasma of only a few minutes oxidizes the
+silicon nitride surface, creating several nanometer thick silicon dioxide
+layers with a compressive stress of 1.30(16)GPa. Such oxide layers can cause a
+reduction of the e ective tensile stress of a 50 nm thick stoichiometric
+silicon nitride membrane by almost 50%. Additionally, intrinsic damping
+linearly increases with the silicon dioxide lm thickness. An oxide layer of
+1.5nm grown in just 10s in a 50W oxygen plasma almost doubled the intrinsic
+damping. The oxide surface layer can be e ciently removed in bu ered HF.",1706.02957v1
+2017-07-03,Quantum behaviour of pumped and damped triangular Bose Hubbard systems,"We propose and analyse analogs of optical cavities for atoms using three-well
+Bose-Hubbard models with pumping and losses. We consider triangular
+configurations. With one well pumped and one damped, we find that both the
+mean-field dynamics and the quantum statistics show a quantitative dependence
+on the choice of damped well. The systems we analyse remain far from
+equilibrium, preserving good coherence between the wells in the steady-state.
+We find quadrature squeezing and mode entanglement for some parameter regimes
+and demonstrate that the trimer with pumping and damping at the same well is
+the stronger option for producing non-classical states. Due to recent
+experimental advances, it should be possible to demonstrate the effects we
+investigate and predict.",1707.01000v1
+2017-07-06,Damping optimization of parameter dependent mechanical systems by rational interpolation,"We consider an optimization problem related to semi-active damping of
+vibrating systems. The main problem is to determine the best damping matrix
+able to minimize influence of the input on the output of the system. We use a
+minimization criteria based on the $\mathcal{H}_2$ system norm.
+  The objective function is non-convex and the associated optimization problem
+typically requires a large number of objective function evaluations. We propose
+an optimization approach that calculates `interpolatory' reduced order models,
+allowing for significant acceleration of the optimization process.
+  In our approach, we use parametric model reduction (PMOR) based on the
+Iterative Rational Krylov Algorithm, which ensures good approximations relative
+to the $\mathcal{H}_2$ system norm, aligning well with the underlying damping
+design objectives. For the parameter sampling that occurs within each PMOR
+cycle, we consider approaches with predetermined sampling and approaches using
+adaptive sampling, and each of these approaches may be combined with three
+possible strategies for internal reduction. In order to preserve important
+system properties, we maintain second-order structure, which through the use of
+modal coordinates, allows for very efficient implementation.
+  The methodology proposed here provides a significant acceleration of the
+optimization process; the gain in efficiency is illustrated in numerical
+experiments.",1707.01789v1
+2017-07-08,Nonlinear dynamics of damped DNA systems with long-range interactions,"We investigate the nonlinear dynamics of a damped Peyrard-Bishop DNA model
+taking into account long-range interactions with distance dependence |l|^-s on
+the elastic coupling constant between different DNA base pairs. Considering
+both Stokes and long-range hydrodynamical damping forces, we use the discrete
+difference operator technique and show in the short wavelength modes that the
+lattice equation can be governed by the complex Ginzburg-Landau equation. We
+found analytically that the technique leads to the correct expression for the
+breather soliton parameters. We found that the viscosity makes the amplitude of
+the breather to damp out. We compare the approximate analytic results with
+numerical simulations for the value s = 3 (dipole-dipole interactions).",1707.02425v1
+2017-08-05,Dynamic Sensitivity Study of MEMS Capacitive Acceleration Transducer Based on Analytical Squeeze Film Damping and Mechanical Thermoelasticity Approaches,"The dynamic behavior of a capacitive micro-electro-mechanical (MEMS)
+accelerometer is evaluated by using a theoretical approach which makes use of a
+squeeze film damping (SFD) model and ideal gas approach. The study investigates
+the performance of the device as a function of the temperature, from 228 K to
+398 K, and pressure, from 20 to 1000 Pa, observing the damping gas trapped
+inside de mechanical transducer. Thermoelastic properties of the silicon bulk
+are considered for the entire range of temperature. The damping gases
+considered are Air, Helium and Argon. The global behavior of the system is
+evaluated considering the electro-mechanical sensitivity (SEM) as the main
+figure of merit in frequency domain. The results show the behavior of the main
+mechanism losses of SFD, as well as the dynamic sensitivity of the MEMS
+transducer system, and are in good agreement with experimental dynamic results
+behavior.",1708.01812v1
+2017-09-01,Scaling of the Rashba spin-orbit torque in magnetic domain walls,"Spin-orbit torque in magnetic domain walls was investigated by solving the
+Pauli-Schr\""{o}dinger equation for the itinerant electrons. The Rashba
+interaction considered is derived from the violation of inversion symmetry at
+interfaces between ferromagnets and heavy metals. In equilibrium, the Rashba
+spin-orbit interaction gives rise to a torque corresponding to the
+Dzyaloshinskii-Moriya interaction. When there is a current flowing, the
+spin-orbit torque experienced by the itinerant electrons in short domain walls
+has both field-like and damping-like components. However, when the domain wall
+width is increased, the damping-like component, which is the counterpart of the
+non-adiabatic spin transfer torque, decreases rapidly at the domain wall
+center. In contrast to the non-adiabatic spin transfer torque, the damping-like
+spin-orbit torque does not approach to zero far away from the domain wall
+center, even in the adiabatic limit. The scattering of spin-up and spin-down
+wave functions, which is caused by the Rashba spin-orbit interaction and the
+spatial variation of magnetization profile in the domain wall, gives rise to
+the finite damping-like spin-orbit torque.",1709.00187v3
+2017-09-12,Temperature effects on MIPs in the BGO calorimeters of DAMPE,"In this paper, we presented a study of temperature effects on BGO
+calorimeters using proton MIP's collected in the first year operation of DAMPE.
+By directly comparing MIP calibration constants used by DAMPE data production
+pipe line, we found an experimental relation between temperature and signal
+amplitudes of each BGO bar: a general deviation of -1.162%/$^{\circ}$C,and
+-0.47%/$^{\circ}$C to -1.60%/$^{\circ}$C statistically for each detector
+element. During 2016, DAMPE's temperature changed by about 7 degrees due to
+solar elevation angle and the corresponding energy scale bias is about 8%. By
+frequent MIP calibration operation, this kind of bias is eliminated to an
+acceptable value.",1709.03735v2
+2017-09-28,Universal and approximate relations for the gravitational-wave damping timescale of $f$-modes in neutron stars,"Existing estimates of the gravitational-wave damping timescale of the
+dominant quadrupole oscillation mode in the case of rapidly rotating stars are
+based on using a Newtonian estimate for the energy of the mode, in combination
+with the lowest-order post-Newtonian quadrupole formula for estimating the
+gravitational-wave luminosity. We investigate a number of other choices for
+estimating the gravitational-wave damping timescale in the nonrotating limit
+and construct a highly accurate, empirically corrected formula that has a
+maximum relative error of only 3% with respect to the perturbative result in
+full general relativity. The expressions involved are sufficiently general to
+be extended to the case of rapidly rotating stars. We also present a new
+higher-order empirical relation for the gravitational-wave damping timescale of
+quadrupole oscillations that is accurate in the whole range of expected values
+for the compactness of neutron stars, without the need for involving the moment
+of inertia.",1709.10067v2
+2017-10-09,Time-dependent propagation speed vs strong damping for degenerate linear hyperbolic equations,"We consider a degenerate abstract wave equation with a time-dependent
+propagation speed. We investigate the influence of a strong dissipation, namely
+a friction term that depends on a power of the elastic operator.
+  We discover a threshold effect. If the propagation speed is regular enough,
+then the damping prevails, and therefore the initial value problem is
+well-posed in Sobolev spaces. Solutions also exhibit a regularizing effect
+analogous to parabolic problems. As expected, the stronger is the damping, the
+lower is the required regularity.
+  On the contrary, if the propagation speed is not regular enough, there are
+examples where the damping is ineffective, and the dissipative equation behaves
+as the non-dissipative one.",1710.03602v1
+2017-10-31,Improving mechanical sensor performance through larger damping,"Mechanical resonances are used in a wide variety of devices; from smart phone
+accelerometers to computer clocks and from wireless communication filters to
+atomic force microscope sensors. Frequency stability, a critical performance
+metric, is generally assumed to be tantamount to resonance quality factor (the
+inverse of the linewidth and of the damping). Here we show that frequency
+stability of resonant nanomechanical sensors can generally be made independent
+of quality factor. At high bandwidths, we show that quality factor reduction is
+completely mitigated by increases in signal to noise ratio. At low bandwidths,
+strikingly, increased damping leads to better stability and sensor resolution,
+with improvement proportional to damping. We confirm the findings by
+demonstrating temperature resolution of 50 \mu K at 200 Hz bandwidth. These
+results open the door for high performance ultrasensitive resonant sensors in
+gaseous or liquid environments, single cell nanocalorimetry, nanoscale gas
+chromatography, and atmospheric pressure nanoscale mass spectrometry.",1710.11280v1
+2017-11-30,The electron-flavored Z'-portal dark matter and the DAMPE cosmic ray excess,"The DAMPE experiment has recently reported strong indications for the
+existence of an excess of high-energy electrons and positrons. If interpreted
+in terms of the annihilation of dark matter, the DAMPE result restricts the
+dark matter mass and possible annihilation channels to a few case. In this
+paper we explain the DAMPE result with the electron-flavored $Z^\prime$-portal
+fermionic dark matter. We show that the Dirac dark matter scenario is promising
+to explain the excess via the process $\bar \chi \chi \to\mathbf{Z}'\to \bar e
+e$. The reduced annihilation cross section is limited in a range of
+$10^{-26}\sim 10^{-24}~{\rm cm^3 s^{-1}}$ to interpret the excess.",1711.11182v2
+2017-12-04,DAMPE Electron-Positron Excess in Leptophilic $Z'$ model,"Recently the DArk Matter Particle Explorer (DAMPE) has reported an excess in
+the electron-positron flux of the cosmic rays which is interpreted as a dark
+matter particle with the mass about $1.5$ TeV. We come up with a leptophilic
+$Z'$ scenario including a Dirac fermion dark matter candidate which beside
+explaining the observed DAMPE excess, is able to pass various
+experimental/observational constraints including the relic density value from
+the WMAP/Planck, the invisible Higgs decay bound at the LHC, the LEP bounds in
+electron-positron scattering, the muon anomalous magnetic moment constraint,
+Fermi-LAT data, and finally the direct detection experiment limits from the
+XENON1t/LUX. By computing the electron-positron flux produced from a dark
+matter with the mass about $1.5$ TeV we show that the model predicts the peak
+observed by the DAMPE.",1712.01239v4
+2017-12-06,Confronting the DAMPE Excess with the Scotogenic Type-II Seesaw Model,"The DArk Matter Particle Explorer (DAMPE) has observed a tentative peak at
+$E\sim1.4~\TeV$ in the cosmic-ray electron spectrum. In this paper, we
+interpret this excess in the scotogenic type-II seesaw model. This model
+extends the canonical type-II seesaw model with dark matter (DM) candidates and
+a loop-induced vacuum expectation value of the triplet scalars, $v_\Delta$,
+resulting in small neutrino masses naturally even for TeV scale triplet
+scalars. Assuming a nearby DM subhalo, the DAMPE excess can be explained by DM
+annihilating into a pair of triplet scalars which subsequently decay to charged
+lepton final states. Spectrum fitting of the DAMPE excess indicates it
+potentially favors the inverted neutrino mass hierarchy. We also discuss how to
+evade associated neutrino flux in our model.",1712.02021v3
+2018-02-28,Beliaev Damping in Spin-$\frac{1}{2}$ Interacting Bosons with Spin-Orbit Coupling,"Beliaev damping provides one of the most important mechanisms for dissipation
+of quasiparticles through beyond-mean-field effects at zero temperature. Here
+we present the first analytical result of Beliaev damping in low-energy
+excitations of spin-$\frac{1}{2}$ interacting bosons with equal Rashba and
+Dresslhaus spin-orbit couplings. We identify novel features of Beliaev decay
+rate due to spin-orbit coupling, in particular, it shows explicit dependence on
+the spin-density interaction and diverges at the interaction-modified phase
+boundary between the zero-momentum and plane-wave phases. This represents a
+manifestation of the effect of spin-orbit coupling in the beyond-mean-field
+regime, which by breaking Galilean invariance couples excitations in the
+density- and spin-channels. By describing the Beliaev damping in terms of the
+observable dynamic structure factors, our results allow direct experimental
+access within current facilities.",1802.10295v1
+2018-03-03,Universal stabilization of single-qubit states using a tunable coupler,"We theoretically analyze a scheme for fast stabilization of arbitrary qubit
+states with high fidelities, extending a protocol recently demonstrated
+experimentally [Lu et al., Phys. Rev. Lett. 119, 150502 (2017)]. That
+experiment utilized red and blue sideband transitions in a system composed of a
+fluxonium qubit, a low-Q LC-oscillator, and a coupler enabling us to tune the
+interaction between them. Under parametric modulations of the coupling
+strength, the qubit can be steered into any desired pure or mixed single-qubit
+state. For realistic circuit parameters, we predict that stabilization can be
+achieved within 100 ns. By varying the ratio between the oscillator's damping
+rate and the effective qubit-oscillator coupling strength, we can switch
+between under-damped, critically-damped, and over-damped stabilization and find
+optimal working points. We further analyze the effect of thermal fluctuations
+and show that the stabilization scheme remains robust for realistic
+temperatures.",1803.01079v3
+2018-04-30,Wave-like blow-up for semilinear wave equations with scattering damping and negative mass term,"In this paper we establish blow-up results and lifespan estimates for
+semilinear wave equations with scattering damping and negative mass term for
+subcritical power, which is the same as that of the corresponding problem
+without mass term, and also the same as that of the corresponding problem
+without both damping and mass term. For this purpose, we have to use the
+comparison argument twice, due to the damping and mass term, in additional to a
+key multiplier. Finally, we get the desired results by an iteration argument.",1804.11073v3
+2018-05-22,Uniqueness of the Cauchy datum for the tempered-in-time response and conductivity operator of a plasma,"We study the linear Vlasov equation with a given electric field $E \in
+\mathcal{S}$, where $\mathcal{S}$ is the space of Schwartz functions. The
+associated damped partial differential equation has a unique tempered solution,
+which fixes the needed Cauchy datum. This tempered solution then converges to
+the causal solution of the linear Vlasov equation when the damping parameter
+goes to zero. This result allows us to define the plasma conductivity operator
+$\sigma$, which gives the current density $j = \sigma (E)$ induced by the
+electric field $E$. We prove that $\sigma$ is continuous from $\mathcal{S}$ to
+its dual $\mathcal{S}^\prime$. We can treat rigorously the case of uniform
+non-magnetized non-relativistic plasma (linear Landau damping) and the case of
+uniform magnetized relativistic plasma (cyclotron damping). In both cases, we
+demonstrate that the main part of the conductivity operator is a
+pseudo-differential operator and we give its expression rigorously. This
+matches the formal results widely used in the theoretical physics community.",1805.08733v3
+2018-05-26,Stabilization for the wave equation with singular Kelvin-Voigt damping,"We consider the wave equation with Kelvin-Voigt damping in a bounded domain.
+The exponential stability result proposed by Liu and Rao or T\'ebou for that
+system assumes that the damping is localized in a neighborhood of the whole or
+a part of the boundary under some consideration. In this paper we propose to
+deal with this geometrical condition by considering a singular Kelvin-Voigt
+damping which is localized faraway from the boundary. In this particular case
+it was proved by Liu and Liu the lack of the uniform decay of the energy.
+However, we show that the energy of the wave equation decreases logarithmically
+to zero as time goes to infinity. Our method is based on the frequency domain
+method. The main feature of our contribution is to write the resolvent problem
+as a transmission system to which we apply a specific Carleman estimate.",1805.10430v1
+2018-06-01,"Fluctuation-damping of isolated, oscillating Bose-Einstein condensates","Experiments on the nonequilibrium dynamics of an isolated Bose-Einstein
+condensate (BEC) in a magnetic double-well trap exhibit a puzzling divergence:
+While some show dissipation-free Josephson oscillations, others find strong
+damping. Such damping in isolated BECs cannot be understood on the level of the
+coherent Gross-Pitaevskii dynamics. Using the Keldysh functional-integral
+formalism, we describe the time-dependent system dynamics by means of a
+multi-mode BEC coupled to fluctuations (single-particle excitations) beyond the
+Gross-Pitaevskii saddle point. We find that the Josephson oscillations excite
+an excess of fluctuations when the effective Josephson frequency,
+$\tilde{\omega}_J$, is in resonance with the effective fluctuation energy,
+$\tilde{\varepsilon}_m$, where both, $\tilde{\omega}_J$ and
+$\tilde{\varepsilon}_m$, are strongly renormalized with respect to their
+noninteracting values. Evaluating and using the model parameters for the
+respective experiments describes quantitatively the presence or absence of
+damping.",1806.00376v2
+2018-06-05,Decoherence assisted spin squeezing generation in superposition of tripartite GHZ and W states,"In the present paper, we study spin squeezing under decoherence in the
+superposition of tripartite maximally entangled GHZ and W states. Here we use
+amplitude damping, phase damping and depolarisation channel. We have
+investigated the dynamics of spin squeezing with the interplay of superposition
+and decoherence parameters with different directions of the mean spin vector.
+We have found the mixture of GHZ and W states is robust against spin squeezing
+generation for amplitude damping and phase damping channels for certain
+directions of the mean spin vector. However, the depolarisation channel
+performs well for spin squeezing generation and generates permanent spin
+squeezing in the superposition of GHZ and W states.",1806.01730v1
+2018-07-31,Dark Matter Particle Explorer observations of high-energy cosmic ray electrons plus positrons and their physical implications,"The DArk Matter Particle Explorer (DAMPE) is a satellite-borne, high-energy
+particle and $\gamma$-ray detector, which is dedicated to indirectly detecting
+particle dark matter and studying high-energy astrophysics. The first results
+about precise measurement of the cosmic ray electron plus positron spectrum
+between 25 GeV and 4.6 TeV were published recently. The DAMPE spectrum reveals
+an interesting spectral softening around $0.9$ TeV and a tentative peak around
+$1.4$ TeV. These results have inspired extensive discussion. The detector of
+DAMPE, the data analysis, and the first results are introduced. In particular,
+the physical interpretations of the DAMPE data are reviewed.",1807.11638v1
+2018-08-08,A Hybrid Dynamic-regenerative Damping Scheme for Energy Regeneration in Variable Impedance Actuators,"Increasing research efforts have been made to improve the energy efficiency
+of variable impedance actuators (VIAs) through reduction of energy consumption.
+However, the harvesting of dissipated energy in such systems remains
+underexplored. This study proposes a novel variable damping module design
+enabling energy regeneration in VIAs by exploiting the regenerative braking
+effect of DC motors. The proposed damping module uses four switches to combine
+regenerative and dynamic braking, in a hybrid approach that enables energy
+regeneration without reduction in the range of damping achievable. Numerical
+simulations and a physical experiment are presented in which the proposed
+module shows an optimal trade-off between task performance and energy
+efficiency.",1808.03143v1
+2018-08-15,$L^1$ estimates for oscillating integrals and their applications to semi-linear models with $σ$-evolution like structural damping,"The present paper is a continuation of our recent paper \cite{DaoReissig}. We
+will consider the following Cauchy problems for semi-linear structurally damped
+$\sigma$-evolution models: \begin{equation*} u_{tt}+ (-\Delta)^\sigma u+ \mu
+(-\Delta)^\delta u_t = f(u,u_t),\, u(0,x)= u_0(x),\, u_t(0,x)=u_1(x)
+\end{equation*} with $\sigma \ge 1$, $\mu>0$ and $\delta \in
+(\frac{\sigma}{2},\sigma]$. Our aim is to study two main models including
+$\sigma$-evolution models with structural damping $\delta \in
+(\frac{\sigma}{2},\sigma)$ and those with visco-elastic damping
+$\delta=\sigma$. Here the function $f(u,u_t)$ stands for power nonlinearities
+$|u|^{p}$ and $|u_t|^{p}$ with a given number $p>1$. We are interested in
+investigating the global (in time) existence of small data solutions to the
+above semi-linear models from suitable spaces basing on $L^q$ space by assuming
+additional $L^{m}$ regularity on the initial data, with $q\in (1,\infty)$ and
+$m\in [1,q)$.",1808.05484v2
+2018-09-26,Permutation-invariant constant-excitation quantum codes for amplitude damping,"The increasing interest in using quantum error correcting codes in practical
+devices has heightened the need for designing quantum error correcting codes
+that can correct against specialized errors, such as that of amplitude damping
+errors which model photon loss. Although considerable research has been devoted
+to quantum error correcting codes for amplitude damping, not so much attention
+has been paid to having these codes simultaneously lie within the decoherence
+free subspace of their underlying physical system. One common physical system
+comprises of quantum harmonic oscillators, and constant-excitation quantum
+codes can be naturally stabilized within them. The purpose of this paper is to
+give constant-excitation quantum codes that not only correct amplitude damping
+errors, but are also immune against permutations of their underlying modes. To
+construct such quantum codes, we use the nullspace of a specially constructed
+matrix based on integer partitions.",1809.09801v4
+2018-09-30,Critical behavior of the damping rate of GHz acoustic phonons in SrTiO3 at the antiferrodistortive phase transition measured by time- and frequency-resolved Brillouin scattering,"We determine the temperature dependent damping rate of longitudinal acoustic
+phonons in SrTiO3 using frequency domain Brillouin scattering and time domain
+Brillouin scattering. We investigate samples with (La,Sr)MnO3 and SrRuO3
+capping layers, which result in compressive or tensile strain at the layer -
+substrate interface, respectively. The different strain states lead to dif-
+ferent domain structures in SrTiO3 that extend into the bulk of the SrTiO3
+substrates and strongly affect the phonon propagation. Our experiments show
+that the damping rate of acoustic phonons in the interfacial STO layer depends
+strongly on the sample temperature and strain induced do- main structure. We
+also show that the damping rate as function of temperature exhibits a critical
+behavior close to the cubic-to-tetragonal phase transition of SrTiO3.",1810.00381v1
+2018-12-04,Spin transport in a magnetic insulator with zero effective damping,"Applications based on spin currents strongly profit from the control and
+reduction of their effective damping and their transport properties. We here
+experimentally observe magnon mediated transport of spin (angular) momentum
+through a 13.4 nm thin yttrium iron garnet film with full control of the
+magnetic damping via spin-orbit torque. Above a critical spin-orbit torque, the
+fully compensated damping manifests itself as an increase of magnon
+conductivity by almost two orders of magnitude. We compare our results to
+theoretical expectations based on recently predicted current induced magnon
+condensates and discuss other possible origins of the observed critical
+behaviour.",1812.01334v3
+2019-01-10,Data-Driven Online Optimization for Enhancing Power System Oscillation Damping,"This paper reports an initial work on power system oscillation damping
+improvement using a data-driven online optimization method. An online
+oscillation damping optimization mod-el is proposed and formulated in a form
+solvable by the data-driven method. Key issues in the online optimization
+procedures, including the damping sensitivity identification method, its
+compatibility with the dispatch plans, as well as other practical issues in
+real large-scale system are discussed. Simulation results based on the 2-area
+4-machine system, and the NETS-NYPS 68-bus system verify the feasibility and
+efficiency of the proposed method. The results also show the capability of the
+proposed method to bridge the gap between online data analysis and complex
+optimization for power system dynamics.",1901.03167v2
+2019-01-15,Continuum damping effects in nuclear collisions associated with twisted boundary conditions,"The time-dependent Skyrme Hartree-Fock calculations have been performed to
+study $^{24}$Mg +$^{24}$Mg collisions. The twisted boundary conditions, which
+can avoid finite box-size effects of the employed 3D coordinate space, have
+been implemented. The prolate deformed $^{24}$Mg has been set to different
+orientations to study vibrations and rotations of the compound nucleus
+$^{48}$Cr. Our time evolution results show continuum damping effects associated
+with the twist-averaged boundary condition play a persistent role after the
+fusion stage. In particular, a rotational damping in continuum is presented in
+calculations of both twist-averaged and absorbing boundary conditions, in which
+damping widths can be clearly extracted. It is unusual that the rotating
+compound nucleus in continuum evolves towards spherical but still has a
+considerable angular momentum.",1901.04736v2
+2019-03-07,Investigating optically-excited THz standing spin waves using noncollinear magnetic bilayers,"We investigate optically excited THz standing spin waves in noncollinear
+magnetic bilayers. Using femtosecond laser-pulse excitation, a spin current is
+generated in the first ferromagnetic (FM) layer, and flows through a conductive
+spacer layer to be injected into the second (transverse) FM layer, where it
+exerts a spin-transfer torque on the magnetization and excites higher-order
+standing spin waves. We show that the noncollinear magnetic bilayer is a
+convenient tool that allows easy excitation of THz spin waves, and can be used
+to investigate the dispersion and thereby the spin wave stiffness parameter in
+the thin-film regime. This is experimentally demonstrated using wedge-shaped Co
+and CoB (absorption) layers. Furthermore, the damping of these THz spin waves
+is investigated, showing a strong increase of the damping with decreasing
+absorption layer thickness, much stronger than expected from interface spin
+pumping effects. Additionally, a previously unseen sudden decrease in the
+damping for the thinnest films is observed. A model for the additional damping
+contribution incorporating both these observations is proposed.",1903.02802v1
+2019-03-14,An analog simulation experiment to study free oscillations of a damped simple pendulum,"The characteristics of drive-free oscillations of a damped simple pendulum
+under sinusoidal potential force field differ from those of the damped harmonic
+oscillations. The frequency of oscillation of a large amplitude simple pendulum
+decreases with increasing amplitude. Many prototype mechanical simple pendulum
+have been fabricated with precision and studied earlier in view of introducing
+them in undergraduate physics laboratories. However, fabrication and
+maintenance of such mechanical pendulum require special skill. In this work, we
+set up an analog electronic simulation experiment to serve the purpose of
+studying the force-free oscillations of a damped simple pendulum. We present
+the details of the setup and some typical results of our experiment. The
+experiment is simple enough to implement in undergraduate physics laboratories.",1903.06162v1
+2019-03-15,Frictional Damping in Biomimetic Scale Beam Oscillations,"Stiff scales adorn the exterior surfaces of fishes, snakes, and many
+reptiles. They provide protection from external piercing attacks and control
+over global deformation behavior to aid locomotion, slithering, and swimming
+across a wide range of environmental condition. In this letter, we investigate
+the dynamic behavior of biomimetic scale substrates for further understanding
+the origins of the nonlinearity that involve various aspect of scales
+interaction, sliding kinematics, interfacial friction, and their combination.
+Particularly, we study the vibrational characteristics through an analytical
+model and numerical investigations for the case of a simply supported scale
+covered beam. Our results reveal for the first time that biomimetic scale beams
+exhibit viscous damping behavior even when only Coulomb friction is postulated
+for free vibrations. We anticipate and quantify the anisotropy in the damping
+behavior with respect to curvature. We also find that unlike static pure
+bending where friction increases bending stiffness, a corresponding increase in
+natural frequency for the dynamic case does not arise for simply supported
+beam. Since both scale geometry, distribution and interfacial properties can be
+easily tailored, our study indicates a biomimetic strategy to design
+exceptional synthetic materials with tailorable damping behavior.",1903.06819v1
+2019-04-08,Damping control in viscoelastic beam dynamics,"Viscoelasticity plays a key role in many practical applications and in
+different reasearch fields, such as in seals, sliding-rolling contacts and
+crack propagation. In all these contexts, a proper knowledge of the
+viscoelastic modulus is very important. However, the experimental
+characterization of the frequency dependent modulus, carried out through
+different standard procedures, still presents some complexities, then possible
+alternative approaches are desirable. For example, the experimental
+investigation of viscoelastic beam dynamics would be challenging, especially
+for the intrinsic simplicity of this kind of test. This is why, a deep
+understanding of damping mechanisms in viscoelastic beams results to be a quite
+important task to better predict their dynamics. With the aim to enlighten
+damping properties in such structures, an analytical study of the transversal
+vibrations of a viscoelastic beam is presented in this paper. Some
+dimensionless parameters are defined, depending on the material properties and
+the beam geometry, which enable to shrewdly design the beam dynamics. In this
+way, by properly tuning such disclosed parameters, for example the
+dimensionless beam length or a chosen material, it is possible to enhance or
+suppress some resonant peaks, one at a time or more simultaneously. This is a
+remarkable possibility to efficiently control damping in these structures, and
+the results presented in this paper may help in elucidating experimental
+procedures for the characterization of viscoelastic materials.",1904.03875v1
+2019-04-28,On the Kolmogorov dissipation law in a damped Navier-Stokes equation,"We consider here the Navier-Stokes equations in $\mathbb{R}^{3}$ with a
+stationary, divergence-free external force and with an additional damping term
+that depends on two parameters. We first study the well-posedness of weak
+solutions for these equations and then, for a particular set of the damping
+parameters, we will obtain an upper and lower control for the energy
+dissipation rate $\varepsilon$ according to the Kolmogorov K41 theory. However,
+although the behavior of weak solutions corresponds to the K41 theory, we will
+show that in some specific cases the damping term introduced in the
+Navier-Stokes equations could annihilate the turbulence even though the Grashof
+number (which are equivalent to the Reynolds number) are large.",1904.12382v1
+2019-04-23,Entanglement sudden death and birth effects in two qubits maximally entangled mixed states under quantum channels,"In the present article, the robustness of entanglement in two qubits
+maximally entangled mixed states (MEME) have been studied under quantum
+decoherence channels. Here we consider bit flip, phase flip, bit-phase-flip,
+amplitude damping, phase damping and depolarization channels. To quantify the
+entanglement, the concurrence has been used as an entanglement measure. During
+this study interesting results have been found for sudden death and birth of
+entanglement under bit flip and bit-phase-flip channels. While amplitude
+damping channel produces entanglement sudden death and does not allow re-birth
+of entanglement. On the other hand, two qubits MEMS exhibit the robust
+character against the phase flip, phase damping and depolarization channels.
+The elegant behavior of all the quantum channels have been investigated with
+varying parameter of quantum state MEMS in different cases.",1904.12630v2
+2019-05-24,Multicomponent Dark Matter in the Light of CALET and DAMPE,"In the light of the latest measurements on the total $e^+ + e^-$ flux by
+CALET and DAMPE experiments, we revisit the multicomponent leptonically
+decaying dark matter (DM) explanations to the cosmic-ray electron/positron
+excesses observed previously. Especially, we use the single and
+double-component DM models to explore the compatibility of the AMS-02 positron
+fraction with the new CALET or DAMPE data. It turns out that neither single nor
+double-component DM models are able to fit the AMS-02 positron fraction and
+DAMPE total $e^+ + e^-$ flux data simultaneously. On the other hand, for the
+combined AMS-02 and CALET dataset, both the single and double-component DM
+models can provide reasonable fits. If we further take into the diffuse
+$\gamma$-ray constraints from Fermi-LAT, only the double-component DM models
+are allowed.",1905.10136v3
+2019-05-30,Quantum dynamical speedup in correlated noisy channels,"The maximal evolution speed of a quantum system can be represented by quantum
+speed limit time (QSLT).We investigate QSLT of a two-qubit system passing
+through a correlated channel (amplitude damping, phase damping, and
+depolarizing).By adjusting the correlation parameter of channel and the initial
+entanglement,a method to accelerate the evolution speed of the system for some
+specific channels is proposed.It is shown that, in amplitude damping channel
+and depolarizing channel,QSLT may be shortened in some cases by increasing
+correlation parameter of the channel and initial entanglement, which are in
+sharp contrast to phase damping channel.In particular, under depolarizing
+channels, the transition from no-speedup evolution to speedup evolution for the
+system can be realized by changing correlation strength of the channel.",1905.12911v3
+2019-07-01,Probing superfluid $^4\mathrm{He}$ with high-frequency nanomechanical resonators down to $\mathrm{mK}$ temperatures,"Superfluids, such as superfluid $^3\mathrm{He}$ and $^4\mathrm{He}$, exhibit
+a broad range of quantum phenomena and excitations which are unique to these
+systems. Nanoscale mechanical resonators are sensitive and versatile force
+detectors with the ability to operate over many orders of magnitude in damping.
+Using nanomechanical-doubly clamped beams of extremely high quality factors
+($Q>10^6$), we probe superfluid $^4\mathrm{He}$ from the superfluid transition
+temperature down to $\mathrm{mK}$ temperatures at frequencies up to $11.6 \,
+\mathrm{MHz}$. Our studies show that nanobeam damping is dominated by
+hydrodynamic viscosity of the normal component of $^4\mathrm{He}$ above
+$1\,\mathrm{K}$. In the temperature range $0.3-0.8\,\mathrm{K}$, the ballistic
+quasiparticles (phonons and rotons) determine the beams' behavior. At lower
+temperatures, damping saturates and is determined either by magnetomotive
+losses or acoustic emission into helium. It is remarkable that all these
+distinct regimes can be extracted with just a single device, despite damping
+changing over six orders of magnitude.",1907.00970v1
+2019-07-15,Asymptotic profiles of solutions for regularity-loss type generalized thermoelastic plate equations and their applications,"In this paper, we consider generalized thermoelastic plate equations with
+Fourier's law of heat conduction. By introducing a threshold for decay
+properties of regularity-loss, we investigate decay estimates of solutions
+with/without regularity-loss in a framework of weighted $L^1$ spaces.
+Furthermore, asymptotic profiles of solutions are obtained by using
+representations of solutions in the Fourier space, which are derived by
+employing WKB analysis. Next, we study generalized thermoelastic plate
+equations with additional structural damping, and analysis the influence of
+structural damping on decay properties and asymptotic profiles of solutions. We
+find that the regularity-loss structure is destroyed by structural damping.
+Finally, we give some applications of our results on thermoelastic plate
+equations and damped Moore-Gibson-Thompson equation.",1907.06344v1
+2019-07-21,Critical Thresholds in One Dimensional Damped Euler-Poisson Systems,"This paper is concerned with the critical threshold phenomenon for one
+dimensional damped, pressureless Euler-Poisson equations with electric force
+induced by a constant background, originally studied in [S. Engelberg and H.
+Liu and E. Tadmor, Indiana Univ. Math. J., 50:109--157, 2001]. A simple
+transformation is used to linearize the characteristic system of equations,
+which allows us to study the geometrical structure of critical threshold curves
+for three damping cases: overdamped, underdamped and borderline damped through
+phase plane analysis. We also derive the explicit form of these critical
+curves. These sharp results state that if the initial data is within the
+threshold region, the solution will remain smooth for all time, otherwise it
+will have a finite time breakdown. Finally, we apply these general results to
+identify critical thresholds for a non-local system subjected to initial data
+on the whole line.",1907.09039v1
+2019-07-23,Ignatyuk damping factor: A semiclassical formula,"Data on nuclear level densities extracted from transmission data or gamma
+energy spectrum store the basic statistical information about nuclei at various
+temperatures. Generally this extracted data goes through model fitting using
+computer codes like CASCADE. However, recently established semiclassical
+methods involving no adjustable parameters to determine the level density
+parameter for magic and semi-magic nuclei give a good agreement with the
+experimental values. One of the popular ways to paramaterize the level density
+parameter which includes the shell effects and its damping was given by
+Ignatyuk. This damping factor is usually fitted from the experimental data on
+nuclear level density and it comes around 0.05 $MeV^{-1}$. In this work we
+calculate the Ignatyuk damping factor for various nuclei using semiclassical
+methods.",1907.09770v1
+2019-08-13,Dynamics of Riemann waves with sharp measure-controlled damping,"This paper is concerned with locally damped semilinear wave equations defined
+on compact Riemannian manifolds with boundary. We present a construction of
+measure-controlled damping regions which are sharp in the sense that their
+summed interior and boundary measures are arbitrarily small. The construction
+of this class of open sets is purely geometric and allows us to prove a new
+observability inequality in terms of potential energy rather than the usual one
+with kinetic energy. A unique continuation property is also proved. Then, in
+three-dimension spaces, we establish the existence of finite dimensional smooth
+global attractors for a class of wave equations with nonlinear damping and
+forces with critical Sobolev growth. In addition, by means of an obstacle
+control condition, we show that our class of measure-controlled regions
+satisfies the well-known geometric control condition (GCC). Therefore, many of
+known results for the stabilization of wave equations hold true in the present
+context.",1908.04814v1
+2019-08-15,Sharp polynomial decay rates for the damped wave equation with Hölder-like damping,"We study decay rates for the energy of solutions of the damped wave equation
+on the torus. We consider dampings invariant in one direction and bounded above
+and below by multiples of $x^{\beta}$ near the boundary of the support and show
+decay at rate $1/t^{\frac{\beta+2}{\beta+3}}$. In the case where $W$ vanishes
+exactly like $x^{\beta}$ this result is optimal by work of the second author.
+The proof uses a version of the Morawetz multiplier method.",1908.05631v3
+2019-08-26,Revisiting the Coulomb-Damped Harmonic Oscillator,"The force of dry friction is studied extensively in introductory physics but
+its effect on oscillations is hardly ever mentioned. Instead, to provide a
+mathematically tractable introduction to damping, virtually all authors adopt a
+viscous resistive force. While exposure to linear damping is of paramount
+importance to the student of physics, the omission of Coulomb damping might
+have a negative impact on the way the students conceive of the subject. In the
+paper, we propose to approximate the action of Coulomb friction on a harmonic
+oscillator by a sinusoidal resistive force whose amplitude is the model's only
+free parameter. We seek the value of this parameter that yields the best fit
+and obtain a closed-form analytic solution, which is shown to nicely fit the
+numerical one.",1908.10363v1
+2019-09-21,Resonant absorption of kink oscillations in coronal flux tubes with continuous magnetic twist,"There are observational evidences for the existence of twisted magnetic field
+in the solar corona. Here, we have investigated resonant damping of the
+magnetohydrodynamic (MHD) kink waves in magnetic flux tubes. A realistic model
+of the tube with continuous magnetic twist and radially inhomogeneous density
+profile has been considered. We have obtained the dispersion relation of the
+kink wave using the solution to the linear MHD equations outside the density
+inhomogeneity and the appropriate connection formula to the solutions across
+the thin transitional boundary layer. The dependence of the oscillation
+frequency and damping rate of the waves on the twist parameter and longitudinal
+wavenumber has been investigated. For the flux tube parameters considered in
+this paper, we obtain rapid damping of the kink waves comparable to the
+observations. In order to justify this rapid damping, depending on the sign of
+the azimuthal kink mode number, $m=+1$ or $m=-1$, the background magnetic field
+must have left handed or right handed twisted profile, respectively. For the
+model considered here, the resonant absorption occurs only when the twist
+parameter is in a range specified by the density contrast.",1909.09787v1
+2019-10-22,Controlled nonlinear magnetic damping in spin-Hall nano-devices,"Large-amplitude magnetization dynamics is substantially more complex compared
+to the low-amplitude linear regime, due to the inevitable emergence of
+nonlinearities. One of the fundamental nonlinear phenomena is the nonlinear
+damping enhancement, which imposes strict limitations on the operation and
+efficiency of magnetic nanodevices. In particular, nonlinear damping prevents
+excitation of coherent magnetization auto-oscillations driven by the injection
+of spin current into spatially extended magnetic regions. Here, we propose and
+experimentally demonstrate that nonlinear damping can be controlled by the
+ellipticity of magnetization precession. By balancing different contributions
+to anisotropy, we minimize the ellipticity and achieve coherent magnetization
+oscillations driven by spatially extended spin current injection into a
+microscopic magnetic disk. Our results provide a novel route for the
+implementation of efficient active spintronic and magnonic devices driven by
+spin current.",1910.09801v1
+2019-10-24,The lifespan of solutions of semilinear wave equations with the scale-invariant damping in two space dimensions,"In this paper, we study the initial value problem for semilinear wave
+equations with the time-dependent and scale-invariant damping in two
+dimensions. Similarly to the one dimensional case by Kato, Takamura and Wakasa
+in 2019, we obtain the lifespan estimates of the solution for a special
+constant in the damping term, which are classified by total integral of the sum
+of the initial position and speed. The key fact is that, only in two space
+dimensions, such a special constant in the damping term is a threshold between
+""wave-like"" domain and ""heat-like"" domain. As a result, we obtain a new type of
+estimate especially for the critical exponent.",1910.11692v2
+2019-11-05,Exceptional points in dissipatively coupled spin dynamics,"We theoretically investigate dynamics of classical spins exchange-coupled
+through an isotropic medium. The coupling is treated at the adiabatic level of
+the medium's response, which mediates a first-order in frequency dissipative
+interaction along with an instantaneous Heisenberg exchange. The resultant
+damped spin precession yields exceptional points (EPs) in the coupled spin
+dynamics, which should be experimentally accessible with the existing magnetic
+heterostructures. In particular, we show that an EP is naturally approached in
+an antiferromagnetic dimer by controlling local damping, while the same is
+achieved by tuning the dissipative coupling between spins in the ferromagnetic
+case. Extending our treatment to one-dimensional spin chains, we show how EPs
+can emerge within the magnonic Brillouin zone by tuning the dissipative
+properties. The critical point, at which an EP pair emerges out of the
+Brillouin zone center, realizes a gapless Weyl point in the magnon spectrum.
+Tuning damping beyond this critical point produces synchronization (level
+attraction) of magnon modes over a finite range of momenta, both in ferro- and
+antiferromagnetic cases. We thus establish that damped magnons can generically
+yield singular points in their band structure, close to which their kinematic
+properties, such as group velocity, become extremely sensitive to the control
+parameters.",1911.01619v2
+2019-11-08,Influence of Sensor Feedback Limitations on Power Oscillation Damping and Transient Stability,"Fundamental sensor feedback limitations for improving rotor angle stability
+using local frequency or phase angle measurement are derived. Using a
+two-machine power system model, it is shown that improved damping of inter-area
+oscillations must come at the cost of reduced transient stability margins,
+regardless of the control design method. The control limitations stem from that
+the excitation of an inter-area mode by external disturbances cannot be
+estimated with certainty using local frequency information. The results are
+validated on a modified Kundur four-machine two-area test system where the
+active power is modulated on an embedded high-voltage dc link. Damping control
+using local phase angle measurements, unavoidably leads to an increased rotor
+angle deviation following certain load disturbances. For a highly stressed
+system, it is shown that this may lead to transient instability. The
+limitations derived in the paper may motivate the need for wide-area
+measurements in power oscillation damping control.",1911.03342v3
+2019-11-12,Non-uniform Stability of Damped Contraction Semigroups,"We investigate the stability properties of strongly continuous semigroups
+generated by operators of the form $A-BB^\ast$, where $A$ is a generator of a
+contraction semigroup and $B$ is a possibly unbounded operator. Such systems
+arise naturally in the study of hyperbolic partial differential equations with
+damping on the boundary or inside the spatial domain. As our main results we
+present general sufficient conditions for non-uniform stability of the
+semigroup generated by $A-BB^\ast$ in terms of selected observability-type
+conditions of the pair $(B^\ast,A)$. We apply the abstract results to obtain
+rates of energy decay in one-dimensional and two-dimensional wave equations, a
+damped fractional Klein--Gordon equation and a weakly damped beam equation.",1911.04804v3
+2020-01-31,Dynamo in weakly collisional nonmagnetized plasmas impeded by Landau damping of magnetic fields,"We perform fully kinetic simulations of flows known to produce dynamo in
+magnetohydrodynamics (MHD), considering scenarios with low Reynolds number and
+high magnetic Prandtl number, relevant for galaxy cluster scale fluctuation
+dynamos. We find that Landau damping on the electrons leads to a rapid decay of
+magnetic perturbations, impeding the dynamo. This collisionless damping process
+operates on spatial scales where electrons are nonmagnetized, reducing the
+range of scales where the magnetic field grows in high magnetic Prandtl number
+fluctuation dynamos. When electrons are not magnetized down to the resistive
+scale, the magnetic energy spectrum is expected to be limited by the scale
+corresponding to magnetic Landau damping or, if smaller, the electron
+gyroradius scale, instead of the resistive scale. In simulations we thus
+observe decaying magnetic fields where resistive MHD would predict a dynamo.",2001.11929v2
+2020-03-05,Sound propagation and quantum limited damping in a two-dimensional Fermi gas,"Strongly interacting two-dimensional Fermi systems are one of the great
+remaining challenges in many-body physics due to the interplay of strong local
+correlations and enhanced long-range fluctuations. Here, we probe the
+thermodynamic and transport properties of a 2D Fermi gas across the BEC-BCS
+crossover by studying the propagation and damping of sound modes. We excite
+particle currents by imprinting a phase step onto homogeneous Fermi gases
+trapped in a box potential and extract the speed of sound from the frequency of
+the resulting density oscillations. We measure the speed of sound across the
+BEC-BCS crossover and compare the resulting dynamic measurement of the equation
+of state both to a static measurement based on recording density profiles and
+to Quantum Monte Carlo calculations and find reasonable agreement between all
+three. We also measure the damping of the sound mode, which is determined by
+the shear and bulk viscosities as well as the thermal conductivity of the gas.
+We find that the damping is minimal in the strongly interacting regime and the
+diffusivity approaches the universal quantum bound $\hbar/m$ of a perfect
+fluid.",2003.02713v1
+2020-03-09,Proof-of-principle direct measurement of Landau damping strength at the Large Hadron Collider with an anti-damper,"Landau damping is an essential mechanism for ensuring collective beam
+stability in particle accelerators. Precise knowledge of how strong Landau
+damping is, is key to making accurate predictions on beam stability for
+state-of-the-art high energy colliders. In this paper we demonstrate an
+experimental procedure that would allow quantifying the strength of Landau
+damping and the limits of beam stability using an active transverse feedback as
+a controllable source of beam coupling impedance. In a proof-of-principle test
+performed at the Large Hadron Collider stability diagrams for a range of Landau
+Octupole strengths have been measured. In the future, the procedure could
+become an accurate way of measuring stability diagrams throughout the machine
+cycle.",2003.04383v1
+2020-03-19,An inverse-system method for identification of damping rate functions in non-Markovian quantum systems,"Identification of complicated quantum environments lies in the core of
+quantum engineering, which systematically constructs an environment model with
+the aim of accurate control of quantum systems. In this paper, we present an
+inverse-system method to identify damping rate functions which describe
+non-Markovian environments in time-convolution-less master equations. To access
+information on the environment, we couple a finite-level quantum system to the
+environment and measure time traces of local observables of the system. By
+using sufficient measurement results, an algorithm is designed, which can
+simultaneously estimate multiple damping rate functions for different
+dissipative channels. Further, we show that identifiability for the damping
+rate functions corresponds to the invertibility of the system and a necessary
+condition for identifiability is also given. The effectiveness of our method is
+shown in examples of an atom and three-spin-chain non-Markovian systems.",2003.08617v1
+2020-04-23,Damping of gravitational waves in 2-2-holes,"A 2-2-hole is an explicit realization of a horizonless object that can still
+very closely resemble a BH. An ordinary relativistic gas can serve as the
+matter source for the 2-2-hole solution of quadratic gravity, and this leads to
+a calculable area-law entropy. Here we show that it also leads to an estimate
+of the damping of a gravitational wave as it travels to the center of the
+2-2-hole and back out again. We identify two frequency dependent effects that
+greatly diminish the damping. Spinning 2-2-hole solutions are not known, but we
+are still able to consider some spin dependent effects. The frequency and spin
+dependence of the damping helps to determine the possible echo resonance signal
+from the rotating remnants of merger events. It also controls the fate of the
+ergoregion instability.",2004.11285v3
+2020-05-04,Plasmon damping in electronically open systems,"Rapid progress in electrically-controlled plasmonics in solids poses a
+question about effects of electronic reservoirs on the properties of plasmons.
+We find that plasmons in electronically open systems [i.e. in (semi)conductors
+connected to leads] are prone to an additional damping due to charge carrier
+penetration into contacts and subsequent thermalization. We develop a theory of
+such lead-induced damping based on kinetic equation with self-consistent
+electric field, supplemented by microscopic carrier transport at the
+interfaces. The lifetime of plasmon in electronically open ballistic system
+appears to be finite, order of conductor length divided by carrier Fermi
+(thermal) velocity. The reflection loss of plasmon incident on the contact of
+semi-conductor and perfectly conducting metal also appears to be finite, order
+of Fermi velocity divided by wave phase velocity. Recent experiments on
+plasmon-assisted photodetection are discussed in light of the proposed
+lead-induced damping phenomenon.",2005.01680v1
+2020-05-06,Helical damping and anomalous critical non-Hermitian skin effect,"Non-Hermitian skin effect and critical skin effect are unique features of
+non-Hermitian systems. In this Letter, we study an open system with its
+dynamics of single-particle correlation function effectively dominated by a
+non-Hermitian damping matrix, which exhibits $\mathbb{Z}_2$ skin effect, and
+uncover the existence of a novel phenomenon of helical damping. When adding
+perturbations that break anomalous time reversal symmetry to the system, the
+critical skin effect occurs, which causes the disappearance of the helical
+damping in the thermodynamic limit although it can exist in small size systems.
+We also demonstrate the existence of anomalous critical skin effect when we
+couple two identical systems with $\mathbb{Z}_2$ skin effect. With the help of
+non-Bloch band theory, we unveil that the change of generalized Brillouin zone
+equation is the necessary condition of critical skin effect.",2005.02617v1
+2020-05-16,Gravitational Landau Damping for massive scalar modes,"We establish the possibility of Landau damping for gravitational scalar waves
+which propagate in a non-collisional gas of particles. In particular, under the
+hypothesis of homogeneity and isotropy, we describe the medium at the
+equilibrium with a J\""uttner-Maxwell distribution, and we analytically
+determine the damping rate from the Vlasov equation. We find that damping
+occurs only if the phase velocity of the wave is subluminal throughout the
+propagation within the medium. Finally, we investigate relativistic media in
+cosmological settings by adopting numerical techniques.",2005.08010v4
+2020-05-21,"On Strong Feller Property, Exponential Ergodicity and Large Deviations Principle for Stochastic Damping Hamiltonian Systems with State-Dependent Switching","This work focuses on a class of stochastic damping Hamiltonian systems with
+state-dependent switching, where the switching process has a countably infinite
+state space. After establishing the existence and uniqueness of a global weak
+solution via the martingale approach under very mild conditions, the paper next
+proves the strong Feller property for regime-switching stochastic damping
+Hamiltonian systems by the killing technique together with some resolvent and
+transition probability identities. The commonly used continuity assumption for
+the switching rates $q_{kl}(\cdot)$ in the literature is relaxed to
+measurability in this paper. Finally the paper provides sufficient conditions
+for exponential ergodicity and large deviations principle for regime-switching
+stochastic damping Hamiltonian systems. Several examples on regime-switching
+van der Pol and (overdamped) Langevin systems are studied in detail for
+illustration.",2005.10730v1
+2020-06-14,Bulk Viscous Damping of Density Oscillations in Neutron Star Mergers,"In this paper, we discuss the damping of density oscillations in dense
+nuclear matter in the temperature range relevant to neutron star mergers. This
+damping is due to bulk viscosity arising from the weak interaction ``Urca''
+processes of neutron decay and electron capture. The nuclear matter is modelled
+in the relativistic density functional approach. The bulk viscosity reaches a
+resonant maximum close to the neutrino trapping temperature, then drops rapidly
+as temperature rises into the range where neutrinos are trapped in neutron
+stars. We investigate the bulk viscous dissipation timescales in a post-merger
+object and identify regimes where these timescales are as short as the
+characteristic timescale $\sim$10 ms, and, therefore, might affect the
+evolution of the post-merger object. Our analysis indicates that bulk viscous
+damping would be important at not too high temperatures of the order of a few
+MeV and densities up to a few times saturation density.",2006.07975v2
+2020-06-15,Exact solutions of a damped harmonic oscillator in a time dependent noncommutative space,"In this paper we have obtained the exact eigenstates of a two dimensional
+damped harmonic oscillator in time dependent noncommutative space. It has been
+observed that for some specific choices of the damping factor and the time
+dependent frequency of the oscillator, there exists interesting solutions of
+the time dependent noncommutative parameters following from the solutions of
+the Ermakov-Pinney equation. Further, these solutions enable us to get exact
+analytic forms for the phase which relates the eigenstates of the Hamiltonian
+with the eigenstates of the Lewis invariant. We then obtain expressions for the
+matrix elements of the coordinate operators raised to a finite arbitrary power.
+From these general results we then compute the expectation value of the
+Hamiltonian. The expectation values of the energy are found to vary with time
+for different solutions of the Ermakov-Pinney equation corresponding to
+different choices of the damping factor and the time dependent frequency of the
+oscillator.",2006.08611v1
+2020-06-16,Enhancing nonlinear damping by parametric-direct internal resonance,"Mechanical sources of nonlinear damping play a central role in modern
+physics, from solid-state physics to thermodynamics. The microscopic theory of
+mechanical dissipation [M. I . Dykman, M. A. Krivoglaz, Physica Status Solidi
+(b) 68, 111 (1975)] suggests that nonlinear damping of a resonant mode can be
+strongly enhanced when it is coupled to a vibration mode that is close to twice
+its resonance frequency. To date, no experimental evidence of this enhancement
+has been realized. In this letter, we experimentally show that nanoresonators
+driven into parametric-direct internal resonance provide supporting evidence
+for the microscopic theory of nonlinear dissipation. By regulating the drive
+level, we tune the parametric resonance of a graphene nanodrum over a range of
+40-70 MHz to reach successive two-to-one internal resonances, leading to a
+nearly two-fold increase of the nonlinear damping. Our study opens up an
+exciting route towards utilizing modal interactions and parametric resonance to
+realize resonators with engineered nonlinear dissipation over wide frequency
+range.",2006.09364v3
+2020-06-22,Blow-up for wave equation with the scale-invariant damping and combined nonlinearities,"In this article, we study the blow-up of the damped wave equation in the
+\textit{scale-invariant case} and in the presence of two nonlinearities. More
+precisely, we consider the following equation: $$u_{tt}-\Delta
+u+\frac{\mu}{1+t}u_t=|u_t|^p+|u|^q, \quad \mbox{in}\ \R^N\times[0,\infty), $$
+with small initial data.\\ For $\mu < \frac{N(q-1)}{2}$ and $\mu \in (0,
+\mu_*)$, where $\mu_*>0$ is depending on the nonlinearties' powers and the
+space dimension ($\mu_*$ satisfies $(q-1)\left((N+2\mu_*-1)p-2\right) = 4$), we
+prove that the wave equation, in this case, behaves like the one without
+dissipation ($\mu =0$). Our result completes the previous studies in the case
+where the dissipation is given by $\frac{\mu}{(1+t)^\beta}u_t; \ \beta >1$
+(\cite{LT3}), where, contrary to what we obtain in the present work, the effect
+of the damping is not significant in the dynamics. Interestingly, in our case,
+the influence of the damping term $\frac{\mu}{1+t}u_t$ is important.",2006.12600v1
+2020-07-10,Decentralized Frequency Control using Packet-based Energy Coordination,"This paper presents a novel frequency-responsive control scheme for
+demand-side resources, such as electric water heaters. A frequency-dependent
+control law is designed to provide damping from distributed energy resources
+(DERs) in a fully decentralized fashion. This local control policy represents a
+frequency-dependent threshold for each DER that ensures that the aggregate
+response provides damping during frequency deviations. The proposed
+decentralized policy is based on an adaptation of a packet-based DER
+coordination scheme where each device send requests for energy access (also
+called an ""energy packet"") to an aggregator. The number of previously accepted
+active packets can then be used a-priori to form an online estimate of the
+aggregate damping capability of the DER fleet in a dynamic power system. A
+simple two-area power system is used to illustrate and validate performance of
+the decentralized control policy and the accuracy of the online damping
+estimating for a fleet of 400,000 DERs.",2007.05624v1
+2020-07-30,Origin of micron-scale propagation lengths of heat-carrying acoustic excitations in amorphous silicon,"The heat-carrying acoustic excitations of amorphous silicon are of interest
+because their mean free paths may approach micron scales at room temperature.
+Despite extensive investigation, the origin of the weak acoustic damping in the
+heat-carrying frequencies remains a topic of debate. Here, we report
+measurements of the thermal conductivity mean free path accumulation function
+in amorphous silicon thin films from 60 - 315 K using transient grating
+spectroscopy. With additional picosecond acoustics measurements and considering
+the known frequency-dependencies of damping mechanisms in glasses, we
+reconstruct the mean free paths from $\sim 0.1-3$ THz. The mean free paths are
+independent of temperature and exhibit a Rayleigh scattering trend over most of
+this frequency range. The observed trend is inconsistent with the predictions
+of numerical studies based on normal mode analysis but agrees with diverse
+measurements on other glasses. The micron-scale MFPs in amorphous Si arise from
+the absence of anharmonic or two-level system damping in the sub-THz
+frequencies, leading to heat-carrying acoustic excitations with
+room-temperature damping comparable to that of other glasses at cryogenic
+temperatures.",2007.15777v2
+2020-08-06,Quantum sensing of open systems: Estimation of damping constants and temperature,"We determine quantum precision limits for estimation of damping constants and
+temperature of lossy bosonic channels. A direct application would be the use of
+light for estimation of the absorption and the temperature of a transparent
+slab. Analytic lower bounds are obtained for the uncertainty in the estimation,
+through a purification procedure that replaces the master equation description
+by a unitary evolution involving the system and ad hoc environments. For zero
+temperature, Fock states are shown to lead to the minimal uncertainty in the
+estimation of damping, with boson-counting being the best measurement
+procedure. In both damping and temperature estimates, sequential
+pre-thermalization measurements, through a stream of single bosons, may lead to
+huge gain in precision.",2008.02728v1
+2020-08-07,Quantifying the evidence for resonant damping of coronal waves with foot-point wave power asymmetry,"We use Coronal Multi-channel Polarimeter (CoMP) observations of propagating
+waves in the solar corona and Bayesian analysis to assess the evidence of
+models with resonant damping and foot-point wave power asymmetries. Two nested
+models are considered. The reduced model considers resonant damping as the sole
+cause of the measured discrepancy between outward and inward wave power. The
+larger model contemplates an extra source of asymmetry with origin at the
+foot-points. We first compute probability distributions of parameters
+conditional on the models and the observed data. The obtained constraints are
+then used to calculate the evidence for each model in view of data. We find
+that we need to consider the larger model to explain CoMP data and to
+accurately infer the damping ratio, hence, to better assess the possible
+contribution of the waves to coronal heating.",2008.03004v1
+2020-08-22,Sound damping in frictionless granular materials: The interplay between configurational disorder and inelasticity,"We numerically investigate sound damping in a model of granular materials in
+two dimensions. We simulate evolution of standing waves in disordered
+frictionless disks and analyze their damped oscillations by velocity
+autocorrelation functions and power spectra. We control the strength of
+inelastic interactions between the disks in contact to examine the effect of
+energy dissipation on sound characteristics of disordered systems. Increasing
+the strength of inelastic interactions, we find that (i) sound softening
+vanishes and (ii) sound attenuation due to configurational disorder, i.e. the
+Rayleigh scattering at low frequencies and disorder-induced broadening at high
+frequencies, is completely dominated by the energy dissipation. Our findings
+suggest that sound damping in granular media is determined by the interplay
+between elastic heterogeneities and inelastic interactions.",2008.09760v1
+2020-09-27,Squeezed comb states,"Continuous-variable codes are an expedient solution for quantum information
+processing and quantum communication involving optical networks. Here we
+characterize the squeezed comb, a finite superposition of equidistant squeezed
+coherent states on a line, and its properties as a continuous-variable encoding
+choice for a logical qubit. The squeezed comb is a realistic approximation to
+the ideal code proposed by Gottesman, Kitaev, and Preskill [Phys. Rev. A 64,
+012310 (2001)], which is fully protected against errors caused by the
+paradigmatic types of quantum noise in continuous-variable systems: damping and
+diffusion. This is no longer the case for the code space of finite squeezed
+combs, and noise robustness depends crucially on the encoding parameters. We
+analyze finite squeezed comb states in phase space, highlighting their
+complicated interference features and characterizing their dynamics when
+exposed to amplitude damping and Gaussian diffusion noise processes. We find
+that squeezed comb state are more suitable and less error-prone when exposed to
+damping, which speaks against standard error correction strategies that employ
+linear amplification to convert damping into easier-to-describe isotropic
+diffusion noise.",2009.12888v2
+2020-11-16,Switchable Damping for a One-Particle Oscillator,"The possibility to switch the damping rate for a one-electron oscillator is
+demonstrated, for an electron that oscillates along the magnetic field axis in
+a Penning trap. Strong axial damping can be switched on to allow this
+oscillation to be used for quantum nondemolition detection of the cyclotron and
+spin quantum state of the electron. Weak axial damping can be switched on to
+circumvent the backaction of the detection motion that has limited past
+measurements. The newly developed switch will reduce the linewidth of the
+cyclotron transition of one-electron by two orders of magnitude.",2011.08136v2
+2020-11-17,Challenging an experimental nonlinear modal analysis method with a new strongly friction-damped structure,"In this work, we show that a recently proposed method for experimental
+nonlinear modal analysis based on the extended periodic motion concept is well
+suited to extract modal properties for strongly nonlinear systems (i.e. in the
+presence of large frequency shifts, high and nonlinear damping, changes of the
+mode shape, and higher harmonics). To this end, we design a new test rig that
+exhibits a large extent of friction-induced damping (modal damping ratio up to
+15 %) and frequency shift by 36 %. The specimen, called RubBeR, is a
+cantilevered beam under the influence of dry friction, ranging from full stick
+to mainly sliding. With the specimen's design, the measurements are well
+repeatable for a system subjected to dry frictional force. Then, we apply the
+method to the specimen and show that single-point excitation is sufficient to
+track the modal properties even though the deflection shape changes with
+amplitude. Computed frequency responses using a single nonlinear-modal
+oscillator with the identified modal properties agree well with measured
+reference curves of different excitation levels, indicating the modal
+properties' significance and accuracy.",2011.08527v1
+2020-11-27,Thermal damping of Weak Magnetosonic Turbulence in the Interstellar Medium,"We present a generic mechanism for the thermal damping of compressive waves
+in the interstellar medium (ISM), occurring due to radiative cooling. We solve
+for the dispersion relation of magnetosonic waves in a two-fluid (ion-neutral)
+system in which density- and temperature-dependent heating and cooling
+mechanisms are present. We use this dispersion relation, in addition to an
+analytic approximation for the nonlinear turbulent cascade, to model
+dissipation of weak magnetosonic turbulence. We show that in some ISM
+conditions, the cutoff wavelength for magnetosonic turbulence becomes tens to
+hundreds of times larger when the thermal damping is added to the regular
+ion-neutral damping. We also run numerical simulations which confirm that this
+effect has a dramatic impact on cascade of compressive wave modes.",2011.13879v3
+2021-02-10,WAMS-Based Model-Free Wide-Area Damping Control by Voltage Source Converters,"In this paper, a novel model-free wide-area damping control (WADC) method is
+proposed, which can achieve full decoupling of modes and damp multiple critical
+inter-area oscillations simultaneously using grid-connected voltage source
+converters (VSCs). The proposed method is purely measurement based and requires
+no knowledge of the network topology and the dynamic model parameters. Hence,
+the designed controller using VSCs can update the control signals online as the
+system operating condition varies. Numerical studies in the modified IEEE
+68-bus system with grid-connected VSCs show that the proposed method can
+estimate the system dynamic model accurately and can damp inter-area
+oscillations effectively under different working conditions and network
+topologies.",2102.05494v1
+2021-04-08,Fast optimization of viscosities for frequency-weighted damping of second-order systems,"We consider frequency-weighted damping optimization for vibrating systems
+described by a second-order differential equation. The goal is to determine
+viscosity values such that eigenvalues are kept away from certain undesirable
+areas on the imaginary axis. To this end, we present two complementary
+techniques. First, we propose new frameworks using nonsmooth constrained
+optimization problems, whose solutions both damp undesirable frequency bands
+and maintain stability of the system. These frameworks also allow us to weight
+which frequency bands are the most important to damp. Second, we also propose a
+fast new eigensolver for the structured quadratic eigenvalue problems that
+appear in such vibrating systems. In order to be efficient, our new eigensolver
+exploits special properties of diagonal-plus-rank-one complex symmetric
+matrices, which we leverage by showing how each quadratic eigenvalue problem
+can be transformed into a short sequence of such linear eigenvalue problems.
+The result is an eigensolver that is substantially faster than standard
+techniques. By combining this new solver with our new optimization frameworks,
+we obtain our overall algorithm for fast computation of optimal viscosities.
+The efficiency and performance of our new methods are verified and illustrated
+on several numerical examples.",2104.04035v1
+2021-04-12,Slow periodic oscillation without radiation damping: New evolution laws for rate and state friction,"The dynamics of sliding friction is mainly governed by the frictional force.
+Previous studies have shown that the laboratory-scale friction is well
+described by an empirical law stated in terms of the slip velocity and the
+state variable. The state variable represents the detailed physicochemical
+state of the sliding interface. Despite some theoretical attempts to derive
+this friction law, there has been no unique equation for time evolution of the
+state variable. Major equations known to date have their own merits and
+drawbacks. To shed light on this problem from a new aspect, here we investigate
+the feasibility of periodic motion without the help of radiation damping.
+Assuming a patch on which the slip velocity is perturbed from the rest of the
+sliding interface, we prove analytically that three major evolution laws fail
+to reproduce stable periodic motion without radiation damping. Furthermore, we
+propose two new evolution equations that can produce stable periodic motion
+without radiation damping. These two equations are scrutinized from the
+viewpoint of experimental validity and the relevance to slow earthquakes.",2104.05398v2
+2021-04-27,Absence of a boson peak in anharmonic phonon models with Akhiezer-type damping,"In a recent article M. Baggioli and A. Zaccone (Phys. Rev. Lett. {\bf 112},
+145501 (2019)) claimed that an anharmonic damping, leading to a sound
+attenuation proportional to $\omega^2$ (Akhiezer-type damping) would imply a
+boson peak, i.e.\ a maximum in the vibrational density of states, divided by
+the frequency squared (reduced density of states). This would apply both to
+glasses and crystals.Here we show that this is not the case. In a
+mathematically correct treatment of the model the reduced density of states
+monotonously decreases, i.e.\ there is no boson peak. We further show that the
+formula for the would-be boson peak, presented by the authors, corresponds to a
+very short one-dimensional damped oscillator system. The peaks they show
+correspond to resonances, which vanish in the thermodynamic limit.",2104.13076v1
+2021-05-03,Damping and polarization rates in near equilibrium state,"The collision terms in spin transport theory are analyzed in Kadanoff-Baym
+formalism for systems close to equilibrium. The non-equilibrium fluctuations in
+spin distribution include both damping and polarization, with the latter
+arising from the exchange between orbital and spin angular momenta. The damping
+and polarization rates or the relaxation times are expressed in terms of
+various Dirac components of the self-energy. Unlike the usually used
+Anderson-Witting relaxation time approximation assuming a single time scale for
+different degrees of freedom, the polarization effect is induced by the thermal
+vorticity and its time scale of thermalization is different from the damping.
+The numerical calculation in the Nambu--Jona-Lasinio model shows that, charge
+is thermalized earlier and spin is thermalized later.",2105.00915v1
+2021-06-07,Voltage-control of damping constant in magnetic-insulator/topological-insulator bilayers,"The magnetic damping constant is a critical parameter for magnetization
+dynamics and the efficiency of memory devices and magnon transport. Therefore,
+its manipulation by electric fields is crucial in spintronics. Here, we
+theoretically demonstrate the voltage-control of magnetic damping in ferro- and
+ferrimagnetic-insulator (FI)/topological-insulator (TI) bilayers. Assuming a
+capacitor-like setup, we formulate an effective dissipation torque induced by
+spin-charge pumping at the FI/TI interface as a function of an applied voltage.
+By using realistic material parameters, we find that the effective damping for
+a FI with 10nm thickness can be tuned by one order of magnitude under the
+voltage with 0.25V. Also, we provide perspectives on the voltage-induced
+modulation of the magnon spin transport on proximity-coupled FIs.",2106.03332v1
+2021-05-14,Exact solution of damped harmonic oscillator with a magnetic field in a time dependent noncommutative space,"In this paper we have obtained the exact eigenstates of a two dimensional
+damped harmonic oscillator in the presence of an external magnetic field
+varying with respect to time in time dependent noncommutative space. It has
+been observed that for some specific choices of the damping factor, the time
+dependent frequency of the oscillator and the time dependent external magnetic
+field, there exists interesting solutions of the time dependent noncommutative
+parameters following from the solutions of the Ermakov-Pinney equation.
+Further, these solutions enable us to get exact analytic forms for the phase
+which relates the eigenstates of the Hamiltonian with the eigenstates of the
+Lewis invariant. Then we compute the expectation value of the Hamiltonian. The
+expectation values of the energy are found to vary with time for different
+solutions of the Ermakov-Pinney equation corresponding to different choices of
+the damping factor, the time dependent frequency of the oscillator and the time
+dependent applied magnetic field. We also compare our results with those in the
+absence of the magnetic field obtained earlier.",2106.05182v1
+2021-06-21,Self-stabilization of light sails by damped internal degrees of freedom,"We consider the motion of a light sail that is accelerated by a powerful
+laser beam. We derive the equations of motion for two proof-of-concept sail
+designs with damped internal degrees of freedom. Using linear stability
+analysis we show that perturbations of the sail movement in all lateral degrees
+of freedom can be damped passively. This analysis also shows complicated
+behaviour akin to that associated with exceptional points in PT-symmetric
+systems in optics and quantum mechanics. The excess heat that is produced by
+the damping mechanism is likely to be substantially smaller than the expected
+heating due to the partial absorption of the incident laser beam by the sail.",2106.10961v1
+2021-07-14,Determining the source of phase noise: Response of a driven Duffing oscillator to low-frequency damping and resonance frequency fluctuations,"We present an analytical calculation of the response of a driven Duffing
+oscillator to low-frequency fluctuations in the resonance frequency and
+damping. We find that fluctuations in these parameters manifest themselves
+distinctively, allowing them to be distinguished. In the strongly nonlinear
+regime, amplitude and phase noise due to resonance frequency fluctuations and
+amplitude noise due to damping fluctuations are strongly attenuated, while the
+transduction of damping fluctuations into phase noise remains of order $1$. We
+show that this can be seen by comparing the relative strengths of the amplitude
+fluctuations to the fluctuations in the quadrature components, and suggest that
+this provides a means to determine the source of low-frequency noise in a
+driven Duffing oscillator.",2107.06879v1
+2021-07-27,Spin transport-induced damping of coherent THz spin dynamics in iron,"We study the damping of perpendicular standing spin-waves (PSSWs) in
+ultrathin Fe films at frequencies up to 2.4 THz. The PSSWs are excited by
+optically generated ultrashort spin current pulses, and probed optically in the
+time domain. Analyzing the wavenumber and thickness dependence of the damping,
+we demonstrate that at sufficiently large wave vectors $k$ the damping is
+dominated by spin transport effects scaling with k^4 and limiting the frequency
+range of observable PSSWs. Although this contribution is known to originate in
+the spin diffusion, we argue that at moderate and large k a more general
+description is necessary and develop a model where the 'transverse spin mean
+free path' is the a key parameter, and estimate it to be ~0.5 nm.",2107.12812v2
+2021-09-03,Stabilization of the damped plate equation under general boundary conditions,"We consider a damped plate equation on an open bounded subset of R^d, or a
+smooth manifold, with boundary, along with general boundary operators
+fulfilling the Lopatinskii-Sapiro condition. The damping term acts on a region
+without imposing a geometrical condition. We derive a resolvent estimate for
+the generator of the damped plate semigroup that yields a logarithmic decay of
+the energy of the solution to the plate equation. The resolvent estimate is a
+consequence of a Carleman inequality obtained for the bi-Laplace operator
+involving a spectral parameter under the considered boundary conditions. The
+derivation goes first though microlocal estimates, then local estimates, and
+finally a global estimate.",2109.01521v2
+2021-09-07,Fluid energy cascade rate and kinetic damping: new insight from 3D Landau-fluid simulations,"Using an exact law for incompressible Hall magnetohydrodynamics (HMHD)
+turbulence, the energy cascade rate is computed from three-dimensional HMHD-CGL
+(bi-adiabatic ions and isothermal electrons) and Landau fluid (LF) numerical
+simulations that feature different intensities of Landau damping over a broad
+range of wavenumbers, typically $0.05\lesssim k_\perp d_i \lesssim100$. Using
+three sets of cross-scale simulations where turbulence is initiated at large,
+medium and small scales, the ability of the fluid energy cascade to ""sense"" the
+kinetic Landau damping at different scales is tested. The cascade rate
+estimated from the exact law and the dissipation calculated directly from the
+simulation are shown to reflect the role of Landau damping in dissipating
+energy at all scales, with an emphasis on the kinetic ones. This result
+provides new prospects on using exact laws for simplified fluid models to
+analyze dissipation in kinetic simulations and spacecraft observations, and new
+insights into theoretical description of collisionless magnetized plasmas.",2109.03123v2
+2021-09-24,Effect of nonlocal transformations on the linearizability and exact solvability of the nonlinear generalized modified Emden type equations,"The nonlinear generalized modified Emden type equations (GMEE) are known to
+be linearizable into simple harmonic oscillator (HO) or damped harmonic
+oscillators (DHO) via some nonlocal transformations. Hereby, we show that the
+structure of the nonlocal transformation and the linearizability into HO or DHO
+determine the nature/structure of the dynamical forces involved (hence,
+determine the structure of the dynamical equation). Yet, a reverse engineering
+strategy is used so that the exact solutions of the emerging GMEE are
+nonlocally transformed to find the exact solutions of the HO and DHO dynamical
+equations. Consequently, whilst the exact solution for the HO remains a
+textbook one, the exact solution for the DHO (never reported elsewhere, to the
+best of our knowledge) turns out to be manifestly the most explicit and general
+solution that offers consistency and comprehensive coverage for the associated
+under-damping, critical-damping, and over-damping cases (i.e., no complex
+settings for the coordinates and/or the velocities are eminent/feasible).
+Moreover, for all emerging dynamical system, we report illustrative figures for
+each solution as well as the corresponding phase-space trajectories as they
+evolve in time.",2109.12059v1
+2022-01-12,Implicit Bias of MSE Gradient Optimization in Underparameterized Neural Networks,"We study the dynamics of a neural network in function space when optimizing
+the mean squared error via gradient flow. We show that in the
+underparameterized regime the network learns eigenfunctions of an integral
+operator $T_{K^\infty}$ determined by the Neural Tangent Kernel (NTK) at rates
+corresponding to their eigenvalues. For example, for uniformly distributed data
+on the sphere $S^{d - 1}$ and rotation invariant weight distributions, the
+eigenfunctions of $T_{K^\infty}$ are the spherical harmonics. Our results can
+be understood as describing a spectral bias in the underparameterized regime.
+The proofs use the concept of ""Damped Deviations"", where deviations of the NTK
+matter less for eigendirections with large eigenvalues due to the occurence of
+a damping factor. Aside from the underparameterized regime, the damped
+deviations point-of-view can be used to track the dynamics of the empirical
+risk in the overparameterized setting, allowing us to extend certain results in
+the literature. We conclude that damped deviations offers a simple and unifying
+perspective of the dynamics when optimizing the squared error.",2201.04738v1
+2022-01-19,Variance-Reduced Stochastic Quasi-Newton Methods for Decentralized Learning: Part II,"In Part I of this work, we have proposed a general framework of decentralized
+stochastic quasi-Newton methods, which converge linearly to the optimal
+solution under the assumption that the local Hessian inverse approximations
+have bounded positive eigenvalues. In Part II, we specify two fully
+decentralized stochastic quasi-Newton methods, damped regularized
+limited-memory DFP (Davidon-Fletcher-Powell) and damped limited-memory BFGS
+(Broyden-Fletcher-Goldfarb-Shanno), to locally construct such Hessian inverse
+approximations without extra sampling or communication. Both of the methods use
+a fixed moving window of $M$ past local gradient approximations and local
+decision variables to adaptively construct positive definite Hessian inverse
+approximations with bounded eigenvalues, satisfying the assumption in Part I
+for the linear convergence. For the proposed damped regularized limited-memory
+DFP, a regularization term is added to improve the performance. For the
+proposed damped limited-memory BFGS, a two-loop recursion is applied, leading
+to low storage and computation complexity. Numerical experiments demonstrate
+that the proposed quasi-Newton methods are much faster than the existing
+decentralized stochastic first-order algorithms.",2201.07733v1
+2022-01-19,Active tuning of plasmon damping via light induced magnetism,"Circularly polarized optical excitation of plasmonic nanostructures causes
+coherent circulating motion of their electrons, which in turn, gives rise to
+strong optically induced magnetization - a phenomenon known as the inverse
+Faraday effect (IFE). In this study we report how the IFE also significantly
+decreases plasmon damping. By modulating the optical polarization state
+incident on achiral plasmonic nanostructures from linear to circular, we
+observe reversible increases of reflectance by 78% as well as simultaneous
+increases of optical field concentration by 35.7% under 10^9 W/m^2 continuous
+wave (CW) optical excitation. These signatures of decreased plasmon damping
+were also monitored in the presence of an externally applied magnetic field
+(0.2 T). The combined interactions allow an estimate of the light-induced
+magnetization, which corresponds to an effective magnetic field of ~1.3 T
+during circularly polarized CW excitation (10^9 W/m^2). We rationalize the
+observed decreases in plasmon damping in terms of the Lorentz forces acting on
+the circulating electron trajectories. Our results outline strategies for
+actively modulating intrinsic losses in the metal, and thereby, the optical
+mode quality and field concentration via opto-magnetic effects encoded in the
+polarization state of incident light.",2201.07842v1
+2022-03-02,Simplified Stability Assessment of Power Systems with Variable-Delay Wide-Area Damping Control,"Power electronic devices such as HVDC and FACTS can be used to improve the
+damping of poorly damped inter-area modes in large power systems. This involves
+the use of wide-area feedback signals, which are transmitted via communication
+networks. The performance of the closed-loop system is strongly influenced by
+the delay associated with wide-area signals. The random nature of this delay
+introduces a switched linear system model. The stability assessment of such a
+system requires linear matrix inequality based approaches. This makes the
+stability analysis more complicated as the system size increases. To address
+this challenge, this paper proposes a delay-processing strategy that simplifies
+the modelling and analysis in discrete-domain. In contrast to the existing
+stability assessment techniques, the proposed approach is advantageous because
+the stability, as well as damping performance, can be accurately predicted by a
+simplified analysis. The proposed methodology is verified with a case study on
+the 2-area 4-machine power system with a series compensated tie-line. The
+results are found to be in accordance with the predictions of the proposed
+simplified analysis.",2203.01362v1
+2022-03-03,Forward-modulated damping estimates and nonlocalized stability of periodic Lugiato-Lefever wave,"In an interesting recent analysis, Haragus-Johnson-Perkins-de Rijk have shown
+modulational stability under localized perturbations of steady periodic
+solutions of the Lugiato-Lefever equation (LLE), in the process pointing out a
+difficulty in obtaining standard ""nonlinear damping estimates"" on modulated
+perturbation variables to control regularity of solutions. Here, we point out
+that in place of standard ""inverse-modulated"" damping estimates, one can
+alternatively carry out a damping estimate on the ""forward-modulated""
+perturbation, noting that norms of forward- and inverse-modulated variables are
+equivalent modulo absorbable errors, thus recovering the classical argument
+structure of Johnson-Noble-Rodrigues-Zumbrun for parabolic systems. This
+observation seems of general use in situations of delicate regularity.
+  Applied in the context of (LLE) it gives the stronger result of stability and
+asymptotic behavior with respect to nonlocalized perturbations.",2203.01770v3
+2022-03-31,Observing Particle Energization above the Nyquist Frequency: An Application of the Field-Particle Correlation Technique,"The field-particle correlation technique utilizes single-point measurements
+to uncover signatures of various particle energization mechanisms in turbulent
+space plasmas. The signature of Landau damping by electrons has been found in
+both simulations and observations from Earth's magnetosheath using this
+technique, but instrumental limitations of spacecraft sampling rates present a
+challenge to discovering the full extent of the presence of Landau damping in
+the solar wind. Theory predicts that field-particle correlations can recover
+velocity-space energization signatures even from data that is undersampled with
+respect to the characteristic frequencies at which the wave damping occurs. To
+test this hypothesis, we perform a high-resoluation gyrokinetic simulation of
+space plasma turbulence, confirm that it contains signatures of electron Landau
+damping, and then systematically reduce the time resolution of the data to
+identify the point at which the signatures become impossible to recover. We
+find results in support of our theoretical prediction and look for a rule of
+thumb that can be compared with the measurement capabilities of spacecraft
+missions to inform the process of applying field-particle correlations to low
+time resolution data.",2204.00104v1
+2022-04-06,A Potential Based Quantization Procedure of the Damped Oscillator,"Nowadays, two of the most prospering fields of physics are quantum computing
+and spintronics. In both, the loss of information and dissipation plays a
+crucial role. In the present work we formulate the quantization of the
+dissipative oscillator, which aids understanding of the above mentioned, and
+creates a theoretical frame to overcome these issues in the future. Based on
+the Lagrangian framework of the damped spring system, the canonically
+conjugated pairs and the Hamiltonian of the system are obtained, by which the
+quantization procedure can be started and consistently applied. As a result,
+the damping quantum wave equation of the dissipative oscillator is deduced, by
+which an exact damping wave solution of this equation is obtained.
+Consequently, we arrive at such an irreversible quantum theory by which the
+quantum losses can be described.",2204.02893v2
+2022-04-19,Role of shape anisotropy on thermal gradient-driven domain wall dynamics in magnetic nanowires,"We investigate the magnetic domain wall (DW) dynamics in uniaxial/biaxial
+nanowires under a thermal gradient (TG). The findings reveal that the DW
+propagates toward the hotter region in both nanowires. The main physics of such
+observations is the magnonic angular momentum transfer to the DW. The hard
+(shape) anisotropy exists in biaxial nanowire, which contributes an additional
+torque, hence DW speed is larger than that in uniaxial nanowire. With lower
+damping, the DW velocity is smaller and DW velocity increases with damping
+which is opposite to usual expectation. To explain this, it is predicted that
+there is a probability to form the standing spin-waves (which do not carry net
+energy/momentum) together with travelling spin-waves if the propagation length
+of thermally-generated spin-waves is larger than the nanowire length. For
+larger-damping, DW decreases with damping since the magnon propagation length
+decreases. Therefore, the above findings might be useful in realizing the
+spintronic (racetrack memory) devices.",2204.09101v2
+2022-04-25,Energy decay estimates for the wave equation with supercritical nonlinear damping,"We consider a damped wave equation in a bounded domain. The damping is
+nonlinear and is homogeneous with degree p -- 1 with p > 2. First, we show that
+the energy of the strong solution in the supercritical case decays as a
+negative power of t; the rate of decay is the same as in the subcritical or
+critical cases, provided that the space dimension does not exceed ten. Next,
+relying on a new differential inequality, we show that if the initial
+displacement is further required to lie in L p , then the energy of the
+corresponding weak solution decays logarithmically in the supercritical case.
+Those new results complement those in the literature and open an important
+breach in the unknown land of super-critical damping mechanisms.",2204.11494v1
+2022-05-07,Proposal for a Damping-Ring-Free Electron Injector for Future Linear Colliders,"The current designs of future electron-positron linear colliders incorporate
+large and complex damping rings to produce asymmetric beams for beamstrahlung
+suppression. Here we present the design of an electron injector capable of
+delivering flat electron beams with phase-space partition comparable to the
+electron-beam parameters produced downstream of the damping ring in the
+proposed international linear collider (ILC) design. Our design does not employ
+a damping ring but is instead based on cross-plane phase-space-manipulation
+techniques. The performance of the proposed configuration, its sensitivity to
+jitter along with its impact on spin-polarization is investigated. The proposed
+paradigm could be adapted to other linear collider concepts under consideration
+and offers a path toward significant cost and complexity reduction.",2205.03736v1
+2022-06-02,Optimal Control of the 3D Damped Navier-Stokes-Voigt Equations with Control Constraints,"In this paper, we consider the 3D Navier-Stokes-Voigt (NSV) equations with
+nonlinear damping $|u|^{r-1}u, r\in[1,\infty)$ in bounded and space-periodic
+domains. We formulate an optimal control problem of minimizing the curl of the
+velocity field in the energy norm subject to the flow velocity satisfying the
+damped NSV equation with a distributed control force. The control also needs to
+obey box-type constraints. For any $r\geq 1,$ the existence and uniqueness of a
+weak solution is discussed when the domain $\Omega$ is periodic/bounded in
+$\mathbb R^3$ while a unique strong solution is obtained in the case of
+space-periodic boundary conditions. We prove the existence of an optimal pair
+for the control problem. Using the classical adjoint problem approach, we show
+that the optimal control satisfies a first-order necessary optimality condition
+given by a variational inequality. Since the optimal control problem is
+non-convex, we obtain a second-order sufficient optimality condition showing
+that an admissible control is locally optimal. Further, we derive optimality
+conditions in terms of adjoint state defined with respect to the growth of the
+damping term for a global optimal control.",2206.00988v2
+2022-06-05,Stationary measures for stochastic differential equations with degenerate damping,"A variety of physical phenomena involve the nonlinear transfer of energy from
+weakly damped modes subjected to external forcing to other modes which are more
+heavily damped. In this work we explore this in (finite-dimensional) stochastic
+differential equations in $\mathbb R^n$ with a quadratic, conservative
+nonlinearity $B(x,x)$ and a linear damping term $-Ax$ which is degenerate in
+the sense that $\mathrm{ker} A \neq \emptyset$. We investigate sufficient
+conditions to deduce the existence of a stationary measure for the associated
+Markov semigroups. Existence of such measures is straightforward if $A$ is full
+rank, but otherwise, energy could potentially accumulate in $\mathrm{ker} A$
+and lead to almost-surely unbounded trajectories, making the existence of
+stationary measures impossible. We give a relatively simple and general
+sufficient condition based on time-averaged coercivity estimates along
+trajectories in neighborhoods of $\mathrm{ker} A$ and many examples where such
+estimates can be made.",2206.02240v1
+2022-06-17,Resolvent estimates for the one-dimensional damped wave equation with unbounded damping,"We study the generator $G$ of the one-dimensional damped wave equation with
+unbounded damping. We show that the norm of the corresponding resolvent
+operator, $\| (G - \lambda)^{-1} \|$, is approximately constant as $|\lambda|
+\to +\infty$ on vertical strips of bounded width contained in the closure of
+the left-hand side complex semi-plane, $\overline{\mathbb{C}}_{-} := \{\lambda
+\in \mathbb{C}: \operatorname{Re} \lambda \le 0\}$. Our proof rests on a
+precise asymptotic analysis of the norm of the inverse of $T(\lambda)$, the
+quadratic operator associated with $G$.",2206.08820v2
+2022-08-04,Lp-asymptotic stability of 1D damped wave equations with localized and nonlinear damping,"In this paper, we study the $L^p$-asymptotic stability with $p\in (1,\infty)$
+of the one-dimensional nonlinear damped wave equation with a localized damping
+and Dirichlet boundary conditions in a bounded domain $(0,1)$. We start by
+addressing the well-posedness problem. We prove the existence and the
+uniqueness of weak solutions for $p\in [2,\infty)$ and the existence and the
+uniqueness of strong solutions for all $p\in [1,\infty)$. The proofs rely on
+the well-posedness already proved in the $L^\infty$ framework by [4] combined
+with a density argument. Then we prove that the energy of strong solutions
+decays exponentially to zero. The proof relies on the multiplier method
+combined with the work that has been done in the linear case in [8].",2208.02779v1
+2022-08-07,"Damping of neutrino oscillations, decoherence and the lengths of neutrino wave packets","Spatial separation of the wave packets (WPs) of neutrino mass eigenstates
+leads to decoherence and damping of neutrino oscillations. Damping can also be
+caused by finite energy resolution of neutrino detectors or, in the case of
+experiments with radioactive neutrino sources, by finite width of the emitted
+neutrino line. We study in detail these two types of damping effects using
+reactor neutrino experiments and experiments with radioactive $^{51}$Cr source
+as examples. We demonstrate that the effects of decoherence by WP separation
+can always be incorporated into a modification of the energy resolution
+function of the detector and so are intimately entangled with it. We estimate
+for the first time the lengths $\sigma_x$ of WPs of reactor neutrinos and
+neutrinos from a radioactive $^{51}$Cr source. The obtained values, $\sigma_x =
+(2\times 10^{-5} - 1.4\times 10^{-4})$ cm, are at least six orders of magnitude
+larger than the currently available experimental lower bounds. We conclude that
+effects of decoherence by WP separation cannot be probed in reactor and
+radioactive source experiments.",2208.03736v2
+2022-08-23,Fate of exceptional points in the presence of nonlinearities,"The non-Hermitian dynamics of open systems deal with how intricate coherent
+effects of a closed system intertwine with the impact of coupling to an
+environment. The system-environment dynamics can then lead to so-called
+exceptional points, which are the open-system marker of phase transitions,
+i.e., the closing of spectral gaps in the complex spectrum. Even in the
+ubiquitous example of the damped harmonic oscillator, the dissipative
+environment can lead to an exceptional point, separating between under-damped
+and over-damped dynamics at a point of critical damping. Here, we examine the
+fate of this exceptional point in the presence of strong correlations, i.e.,
+for a nonlinear oscillator. By employing a functional renormalization group
+approach, we identify non-perturbative regimes of this model where the
+nonlinearity makes the system more robust against the influence of dissipation
+and can remove the exceptional point altogether. The melting of the exceptional
+point occurs above a critical nonlinearity threshold. Interestingly, the
+exceptional point melts faster with increasing temperatures, showing a
+surprising flow to coherent dynamics when coupled to a warm environment.",2208.11205v2
+2022-09-10,"Data-driven, multi-moment fluid modeling of Landau damping","Deriving governing equations of complex physical systems based on first
+principles can be quite challenging when there are certain unknown terms and
+hidden physical mechanisms in the systems. In this work, we apply a deep
+learning architecture to learn fluid partial differential equations (PDEs) of a
+plasma system based on the data acquired from a fully kinetic model. The
+learned multi-moment fluid PDEs are demonstrated to incorporate kinetic effects
+such as Landau damping. Based on the learned fluid closure, the data-driven,
+multi-moment fluid modeling can well reproduce all the physical quantities
+derived from the fully kinetic model. The calculated damping rate of Landau
+damping is consistent with both the fully kinetic simulation and the linear
+theory. The data-driven fluid modeling of PDEs for complex physical systems may
+be applied to improve fluid closure and reduce the computational cost of
+multi-scale modeling of global systems.",2209.04726v1
+2022-09-25,Formation of the cosmic-ray halo: The role of nonlinear Landau damping,"We present a nonlinear model of self-consistent Galactic halo, where the
+processes of cosmic ray (CR) propagation and excitation/damping of MHD waves
+are included. The MHD-turbulence, which prevents CR escape from the Galaxy, is
+entirely generated by the resonant streaming instability. The key mechanism
+controlling the halo size is the nonlinear Landau (NL) damping, which
+suppresses the amplitude of MHD fluctuations and, thus, makes the halo larger.
+The equilibrium turbulence spectrum is determined by a balance of CR excitation
+and NL damping, which sets the regions of diffusive and advective propagation
+of CRs. The boundary $z_{cr}(E)$ between the two regions is the halo size,
+which slowly increases with the energy. For the vertical magnetic field of
+$\sim 1~\mu G$, we estimate $z_{cr} \sim 1$ kpc for GeV protons. The derived
+proton spectrum is in a good agreement with observational data.",2209.12302v1
+2022-10-14,Landau damping for gravitational waves in parity-violating theories,"We discuss how tensor polarizations of gravitational waves can suffer Landau
+damping in the presence of velocity birefringence, when parity symmetry is
+explicitly broken. In particular, we analyze the role of the Nieh-Yan and
+Chern-Simons terms in modified theories of gravity, showing how the
+gravitational perturbation in collisionless media can be characterized by a
+subluminal phase velocity, circumventing the well-known results of General
+Relativity and allowing for the appearance of the kinematic damping. We
+investigate in detail the connection between the thermodynamic properties of
+the medium, such as temperature and mass of the particles interacting with the
+gravitational wave, and the parameters ruling the parity violating terms of the
+models. In this respect, we outline how the dispersion relations can give rise
+in each model to different regions of the wavenumber space, where the phase
+velocity is subluminal, superluminal or does not exist. Quantitative estimates
+on the considered models indicate that the phenomenon of Landau damping is not
+detectable given the sensitivity of present-day instruments.",2210.07673v2
+2022-10-25,Formation of shifted shock for the 3D compressible Euler equations with damping,"In this paper, we show the shock formation of the solutions to the
+3-dimensional (3D) compressible isentropic and irrotational Euler equations
+with damping for the initial short pulse data which was first introduced by
+D.Christodoulou\cite{christodoulou2007}. Due to the damping effect, the
+largeness of the initial data is necessary for the shock formation and we will
+work on the class of large data (in energy sense). Similar to the undamped
+case, the formation of shock is characterized by the collapse of the
+characteristic hypersurfaces and the vanishing of the inverse foliation density
+function $\mu$, at which the first derivatives of the velocity and the density
+blow up. However, the damping effect changes the asymptotic behavior of the
+inverse foliation density function $\mu$ and then shifts the time of shock
+formation compared with the undamped case. The methods in the paper can also be
+extended to a class of $3D$ quasilinear wave equations for the short pulse
+initial data.",2210.13796v1
+2022-10-30,Dynamics of a class of extensible beams with degenerate and non-degenerate nonlocal damping,"This work is concerned with new results on long-time dynamics of a class of
+hyperbolic evolution equations related to extensible beams with three
+distinguished nonlocal nonlinear damping terms. In the first possibly
+degenerate case, the results feature the existence of a family of compact
+global attractors and a thickness estimate for their Kolmogorov's
+$\varepsilon$-entropy. Then, in the non-degenerate context, the structure of
+the helpful nonlocal damping leads to the existence of finite-dimensional
+compact global and exponential attractors. Lastly, in a degenerate and critical
+framework, it is proved the existence of a bounded closed global attractor but
+not compact. To the proofs, we provide several new technical results by means
+of refined estimates that open up perspectives for a new branch of nonlinearly
+damped problems.",2210.16851v1
+2022-11-11,Nonlinear fractional damped wave equation on compact Lie groups,"In this paper, we deal with the initial value fractional damped wave equation
+on $G$, a compact Lie group, with power-type nonlinearity. The aim of this
+manuscript is twofold. First, using the Fourier analysis on compact Lie groups,
+we prove a local in-time existence result in the energy space for the
+fractional damped wave equation on $G$. Moreover, a finite time blow-up result
+is established under certain conditions on the initial data. In the next part
+of the paper, we consider fractional wave equation with lower order terms, that
+is, damping and mass with the same power type nonlinearity on compact Lie
+groups, and prove the global in-time existence of small data solutions in the
+energy evolution space.",2211.06155v1
+2022-11-16,Controlling the motional quality factor of a diamagnetically levitated graphite plate,"Researchers seek methods to levitate matter for a wide variety of purposes,
+ranging from exploring fundamental problems in science, through to developing
+new sensors and mechanical actuators. Many levitation techniques require active
+driving and most can only be applied to objects smaller than a few micrometers.
+Diamagnetic levitation has the strong advantage of being the only form of
+levitation which is passive, requiring no energy input, while also supporting
+massive objects. Known diamagnetic materials which are electrical insulators
+are only weakly diamagnetic, and require large magnetic field gradients to
+levitate. Strong diamagnetic materials which are electrical conductors, such as
+graphite, exhibit eddy damping, restricting motional freedom and reducing their
+potential for sensing applications. In this work we describe a method to
+engineer the eddy damping while retaining the force characteristics provided by
+the diamagnetic material. We study, both experimentally and theoretically, the
+motional damping of a magnetically levitated graphite plate in high vacuum and
+demonstrate that one can control the eddy damping by patterning the plate with
+through-slots which interrupt the eddy currents. We find we can control the
+motional quality factor over a wide range with excellent agreement between the
+experiment and numerical simulations.",2211.08764v1
+2022-12-03,Strong On-Chip Microwave Photon-Magnon Coupling Using Ultra-low Damping Epitaxial Y3Fe5O12 Films at 2 Kelvin,"Y3Fe5O12 is arguably the best magnetic material for magnonic quantum
+information science (QIS) because of its extremely low damping. We report
+ultralow damping at 2 K in epitaxial Y3Fe5O12 thin films grown on a diamagnetic
+Y3Sc2Ga3O12 substrate that contains no rare-earth elements. Using these
+ultralow damping YIG films, we demonstrate for the first time strong coupling
+between magnons in patterned YIG thin films and microwave photons in a
+superconducting Nb resonator. This result paves the road towards scalable
+hybrid quantum systems that integrate superconducting microwave resonators, YIG
+film magnon conduits, and superconducting qubits into on-chip QIS devices.",2212.01708v1
+2022-12-21,Fractional damping effects on the transient dynamics of the Duffing oscillator,"We consider the nonlinear Duffing oscillator in presence of fractional
+damping which is characteristic in different physical situations. The system is
+studied with a smaller and larger damping parameter value, that we call the
+underdamped and overdamped regimes. In both we have studied the relation
+between the fractional parameter, the amplitude of the oscillations and the
+times to reach the asymptotic behavior, called asymptotic times. In the
+overdamped regime, the study shows that, also here, there are oscillations for
+fractional order derivatives and their amplitudes and asymptotic times can
+suddenly change for small variations of the fractional parameter. In addition,
+in this latter regime, a resonant-like behavior can take place for suitable
+values of the parameters of the system. These results are corroborated by
+calculating the corresponding Q-factor. We expect that these results can be
+useful for a better understanding of fractional dynamics and its possible
+applications as in modeling different kind of materials that normally need
+complicated damping terms.",2212.11023v1
+2023-01-19,Damped harmonic oscillator revisited: the fastest route to equilibrium,"Theoretically, solutions of the damped harmonic oscillator asymptotically
+approach equilibrium, i.e., the zero energy state, without ever reaching it
+exactly, and the critically damped solution approaches equilibrium faster than
+the underdamped or the overdamped solution. Experimentally, the systems
+described with this model reach equilibrium when the system's energy has
+dropped below some threshold corresponding to the energy resolution of the
+measuring apparatus. We show that one can (almost) always find an optimal
+underdamped solution that will reach this energy threshold sooner than all
+other underdamped solutions, as well as the critically damped solution, no
+matter how small this threshold is. We also comment on one exception to this
+for a particular type of initial conditions, when a specific overdamped
+solution reaches the equilibrium state sooner than all other solutions. We
+confirm some of our findings experimentally.",2301.08222v2
+2023-01-22,Boundary stabilization of a vibrating string with variable length,"We study small vibrations of a string with time-dependent length $\ell(t)$
+and boundary damping. The vibrations are described by a 1-d wave equation in an
+interval with one moving endpoint at a speed $\ell'(t)$ slower than the speed
+of propagation of the wave c=1. With no damping, the energy of the solution
+decays if the interval is expanding and increases if the interval is shrinking.
+The energy decays faster when the interval is expanding and a constant damping
+is applied at the moving end. However, to ensure the energy decay in a
+shrinking interval, the damping factor $\eta$ must be close enough to the
+optimal value $\eta=1$, corresponding to the transparent condition. In all
+cases, we establish lower and upper estimates for the energy with explicit
+constants.",2301.09086v1
+2023-02-24,Asymptotic behaviour of the semidiscrete FE approximations to weakly damped wave equations with minimal smoothness on initial data,"Exponential decay estimates of a general linear weakly damped wave equation
+are studied with decay rate lying in a range. Based on the $C^0$-conforming
+finite element method to discretize spatial variables keeping temporal variable
+continuous, a semidiscrete system is analysed, and uniform decay estimates are
+derived with precisely the same decay rate as in the continuous case. Optimal
+error estimates with minimal smoothness assumptions on the initial data are
+established, which preserve exponential decay rate, and for a 2D problem, the
+maximum error bound is also proved. The present analysis is then generalized to
+include the problems with non-homogeneous forcing function, space-dependent
+damping, and problems with compensator. It is observed that decay rates are
+improved with large viscous damping and compensator. Finally, some numerical
+experiments are performed to validate the theoretical results established in
+this paper.",2302.12476v1
+2023-02-27,Nonlinear acoustic imaging with damping,"In this paper, we consider an inverse problem for a nonlinear wave equation
+with a damping term and a general nonlinear term. This problem arises in
+nonlinear acoustic imaging and has applications in medical imaging and other
+fields. The propagation of ultrasound waves can be modeled by a quasilinear
+wave equation with a damping term. We show the boundary measurements encoded in
+the Dirichlet-to-Neumann map (DN map) determine the damping term and the
+nonlinearity at the same time. In a more general setting, we consider a
+quasilinear wave equation with a one-form (a first-order term) and a general
+nonlinear term. We prove the one-form and the nonlinearity can be determined
+from the DN map, up to a gauge transformation, under some assumptions.",2302.14174v1
+2023-04-11,Sizable suppression of magnon Hall effect by magnon damping in Cr$_2$Ge$_2$Te$_6$,"Two-dimensional (2D) Heisenberg honeycomb ferromagnets are expected to have
+interesting topological magnon effects as their magnon dispersion can have
+Dirac points. The Dirac points are gapped with finite second nearest neighbor
+Dzyaloshinskii-Moriya interaction, providing nontrivial Berry curvature with
+finite magnon Hall effect. Yet, it is unknown how the topological properties
+are affected by magnon damping. We report the thermal Hall effect in
+Cr$_2$Ge$_2$Te$_6$, an insulating 2D honeycomb ferromagnet with a large Dirac
+magnon gap and significant magnon damping. Interestingly, the thermal Hall
+conductivity in Cr$_2$Ge$_2$Te$_6$ shows the coexisting phonon and magnon
+contributions. Using an empirical two-component model, we successfully estimate
+the magnon contribution separate from the phonon part, revealing that the
+magnon Hall conductivity was 20 times smaller than the theoretical calculation.
+Finally, we suggest that such considerable suppression in the magnon Hall
+conductivity is due to the magnon damping effect in Cr$_2$Ge$_2$Te$_6$.",2304.04922v1
+2023-05-22,Semi-active damping optimization of vibrational systems using the reduced basis method,"In this article, we consider vibrational systems with semi-active damping
+that are described by a second-order model. In order to minimize the influence
+of external inputs to the system response, we are optimizing some damping
+values. As minimization criterion, we evaluate the energy response, that is the
+$\cH_2$-norm of the corresponding transfer function of the system. Computing
+the energy response includes solving Lyapunov equations for different damping
+parameters. Hence, the minimization process leads to high computational costs
+if the system is of large dimension. We present two techniques that reduce the
+optimization problem by applying the reduced basis method to the corresponding
+parametric Lyapunov equations. In the first method, we determine a reduced
+solution space on which the Lyapunov equations and hence the resulting energy
+response values are computed approximately in a reasonable time. The second
+method includes the reduced basis method in the minimization process. To
+evaluate the quality of the approximations, we introduce error estimators that
+evaluate the error in the controllability Gramians and the energy response.
+Finally, we illustrate the advantages of our methods by applying them to two
+different examples.",2305.12946v1
+2023-06-01,A combined volume penalization / selective frequency damping approach for immersed boundary methods: application to moving geometries,"This work extends, to moving geometries, the immersed boundary method based
+on volume penalization and selective frequency damping approach [J. Kou, E.
+Ferrer, A combined volume penalization/selective frequency damping approach for
+immersed boundary methods applied to high-order schemes, Journal of
+Computational Physics (2023)]. To do so, the numerical solution inside the
+solid is decomposed into a predefined movement and an oscillatory part
+(spurious waves), where the latter is damped by an SFD approach combined with
+volume penalization. We challenge the method with two cases. First, a new
+manufactured solution problem is proposed to show that the method can recover
+high-order accuracy. Second, we validate the methodology by simulating the
+laminar flow past a moving cylinder, where improved accuracy of the combined
+method is reported.",2306.00504v1
+2023-06-09,Damped nonlinear Schrödinger equation with Stark effect,"We study the $L^2$-critical damped NLS with a Stark potential. We prove that
+the threshold for global existence and finite time blowup of this equation is
+given by $\|Q\|_2$, where $Q$ is the unique positive radial solution of $\Delta
+Q + |Q|^{4/d} Q = Q$ in $H^1(\mathbb{R}^d)$. Moreover, in any small
+neighborhood of $Q$, there exists an initial data $u_0$ above the ground state
+such that the solution flow admits the log-log blowup speed. This verifies the
+structural stability for the ``$\log$-$\log$ law'' associated to the NLS
+mechanism under the perturbation by a damping term and a Stark potential. The
+proof of our main theorem is based on the Avron-Herbst formula and the
+analogous result for the unperturbed damped NLS.",2306.05931v1
+2023-06-19,New Perspectives and Systematic Approaches for Analyzing Negative Damping-Induced Sustained Oscillation,"Sustained oscillations (SOs) are commonly observed in systems dominated by
+converters. Under specific conditions, even though the origin of SOs can be
+identified through negative damping modes using conventional linear analysis,
+utilizing the describing function to compute harmonic amplitude and frequency
+remains incomplete. This is because a) it can not cover the cases where hard
+limits are not triggered, and b) it can not provide a complete trajectory for
+authentic linear analysis to confirm the presence of SO. Hence, two analytical
+methods are proposed by returning to the essential principle of harmonic
+balance. a) A dedicated approach is proposed to solving steady-state harmonics
+via Newton-Raphson iteration with carefully chosen initial values. The method
+encompasses all potential hard limit triggered cases. b) By employing extended
+multiharmonic linearization theory and considering loop impedance, an authentic
+linear analysis of SO is conducted. The analysis indicates that the initial
+negative damping modes transform into multiple positive damping modes as SO
+develops. Simulation validations are performed on a two-level voltage source
+converter using both PSCAD and RT-LAB. Additionally, valuable insights into the
+work are addressed considering the modularity and scalability of the proposed
+methods.",2306.10839v2
+2023-06-24,Numerical approximation of the invariant distribution for a class of stochastic damped wave equations,"We study a class of stochastic semilinear damped wave equations driven by
+additive Wiener noise. Owing to the damping term, under appropriate conditions
+on the nonlinearity, the solution admits a unique invariant distribution. We
+apply semi-discrete and fully-discrete methods in order to approximate this
+invariant distribution, using a spectral Galerkin method and an exponential
+Euler integrator for spatial and temporal discretization respectively. We prove
+that the considered numerical schemes also admit unique invariant
+distributions, and we prove error estimates between the approximate and exact
+invariant distributions, with identification of the orders of convergence. To
+the best of our knowledge this is the first result in the literature concerning
+numerical approximation of invariant distributions for stochastic damped wave
+equations.",2306.13998v1
+2023-07-31,Estimation of Power in the Controlled Quantum Teleportation through the Witness Operator,"Controlled quantum teleportation (CQT) can be considered as a variant of
+quantum teleportation in which three parties are involved where one party acts
+as the controller. The usability of the CQT scheme depends on two types of
+fidelities viz. conditioned fidelity and non-conditioned fidelity. The
+difference between these fidelities may be termed as power of the controller
+and it plays a vital role in the CQT scheme. Thus, our aim is to estimate the
+power of the controller in such a way so that its estimated value can be
+obtained in an experiment. To achieve our goal, we have constructed a witness
+operator and have shown that its expected value may be used in the estimation
+of the lower bound of the power of the controller. Furthermore, we have shown
+that it is possible to make the standard W state useful in the CQT scheme if
+one of its qubits either passes through the amplitude damping channel or the
+phase damping channel. We have also shown that the phase damping channel
+performs better than the amplitude damping channel in the sense of generating
+more power of the controller in the CQT scheme.",2307.16574v1
+2023-08-03,Triple-Spherical Bessel Function Integrals with Exponential and Gaussian Damping: Towards an Analytic N-Point Correlation Function Covariance Model,"Spherical Bessel functions appear commonly in many areas of physics wherein
+there is both translation and rotation invariance, and often integrals over
+products of several arise. Thus, analytic evaluation of such integrals with
+different weighting functions (which appear as toy models of a given physical
+observable, such as the galaxy power spectrum) is useful. Here we present a
+generalization of a recursion-based method for evaluating such integrals. It
+gives relatively simple closed-form results in terms of Legendre functions (for
+the exponentially-damped case) and Gamma, incomplete Gamma functions, and
+hypergeometric functions (for the Gaussian-damped case). We also present a new,
+non-recursive method to evaluate integrals of products of spherical Bessel
+functions with Gaussian damping in terms of incomplete Gamma functions and
+hypergeometric functions.",2308.01955v2
+2023-08-28,Quantized damped transversal single particle mechanical waves,"In information transfer, the dissipation of a signal may have crucial
+importance. The feasibility of reconstructing the distorted signal also depends
+on this. That is why the study of quantized dissipative transversal single
+particle mechanical waves may have an important role. It may be true,
+particularly on the nanoscale in the case of signal distortion, loss, or
+restoration. Based on the damped oscillator quantum description, we generalize
+the canonical quantization procedure for the transversal waves. Furthermore, we
+deduce the related damped wave equation and the state function. We point out
+the two kinds of solutions of the wave equation. One involves the well-known
+spreading solution superposed with the oscillation, in which the loss of
+information is complete. The other is the Airy function solution, which is
+non-spreading, so there is information loss only due to oscillation damping.
+However, the structure of the wavefront remains unchanged. Thus, this result
+allows signal reconstruction, which is important in restoring the lost
+information.",2308.14820v1
+2023-11-15,Integrated Local Energy Decay for Damped Magnetic Wave Equations on Stationary Space-Times,"We establish local energy decay for damped magnetic wave equations on
+stationary, asymptotically flat space-times subject to the geometric control
+condition. More specifically, we allow for the addition of time-independent
+magnetic and scalar potentials, which negatively affect energy coercivity and
+may add in unwieldy spectral effects. By asserting the non-existence of
+eigenvalues in the lower half-plane and resonances on the real line, we are
+able to apply spectral theory from the work of Metcalfe, Sterbenz, and Tataru
+and combine with a generalization of prior work by the present author to extend
+the latter work and establish local energy decay, under one additional symmetry
+hypothesis. Namely, we assume that either the imaginary part of the magnetic
+potentials are uniformly small or, more interestingly and novelly, that the
+damping term is the dominant principal term in the skew-adjoint part of the
+damped wave operator within the region where the metric perturbation from that
+of Minkowski space is permitted to be large. We also obtain an energy dichotomy
+if we do not prohibit non-zero real resonances. In order to make the structure
+of the argument more cohesive, we contextualize the present work within
+requisite existing theory.",2311.08628v1
+2023-11-15,Applications of $L^p-L^q$ estimates for solutions to semi-linear $σ$-evolution equations with general double damping,"In this paper, we would like to study the linear Cauchy problems for
+semi-linear $\sigma$-evolution models with mixing a parabolic like damping term
+corresponding to $\sigma_1 \in [0,\sigma/2)$ and a $\sigma$-evolution like
+damping corresponding to $\sigma_2 \in (\sigma/2,\sigma]$. The main goals are
+on the one hand to conclude some estimates for solutions and their derivatives
+in $L^q$ setting, with any $q\in [1,\infty]$, by developing the theory of
+modified Bessel functions effectively to control oscillating integrals
+appearing the solution representation formula in a competition between these
+two kinds of damping. On the other hand, we are going to prove the global (in
+time) existence of small data Sobolev solutions in the treatment of the
+corresponding semi-linear equations by applying $(L^{m}\cap L^{q})- L^{q}$ and
+$L^{q}- L^{q}$ estimates, with $q\in (1,\infty)$ and $m\in [1,q)$, from the
+linear models. Finally, some further generalizations will be discussed in the
+end of this paper.",2311.09085v1
+2023-12-07,Generalized Damping Torque Analysis of Ultra-Low Frequency Oscillation in the Jerk Space,"Ultra low frequency oscillation (ULFO) is significantly threatening the power
+system stability. Its unstable mechanism is mostly studied via generalized
+damping torque analysis method (GDTA). However, the analysis still adopts the
+framework established for low frequency oscillation. Hence, this letter
+proposes a GDTA approach in the jerk space for ULFO. A multi-information
+variable is constructed to transform the system into a new state space, where
+it is found that the jerk dynamics of the turbine-generator cascaded system is
+a second-order differential equation. Benefiting from this characteristic, we
+propose a new form for GDTA using jerk dynamics, which is established in the
+frequency-frequency acceleration phase space. Then, analytical expressions of
+all damping torque are provided. Finally, test results verified the proposed
+theoretical results. The negative damping mechanism is revealed, and parameter
+adjustment measures are concluded.",2312.04148v1
+2023-12-08,Selective damping of plasmons in coupled two-dimensional systems by Coulomb drag,"The Coulomb drag is a many-body effect observed in proximized low-dimensional
+systems. It appears as emergence of voltage in one of them upon passage of bias
+current in another. The magnitude of drag voltage can be strongly affected by
+exchange of plasmonic excitations between the layers; however, the reverse
+effect of Coulomb drag on properties of plasmons has not been studied. Here, we
+study the plasmon spectra and damping in parallel two-dimensional systems in
+the presence of Coulomb drag. We find that Coulomb drag leads to selective
+damping of one of the two fundamental plasma modes of a coupled bilayer. For
+identical electron doping of both layers, the drag suppresses the acoustic
+plasma mode; while for symmetric electron-hole doping of the coupled pair, the
+drag suppresses the optical plasma mode. The selective damping can be observed
+both for propagating modes in extended bilayers and for localized plasmons in
+bilayers confined by source and drain contacts. The discussed effect may
+provide access to the strength of Coulomb interaction in 2d electron systems
+from various optical and microwave scattering experiments.",2312.05097v1
+2023-12-13,Geometrical Interpretation of Neutrino Oscillation with decay,"The geometrical representation of two-flavor neutrino oscillation represents
+the neutrino's flavor eigenstate as a magnetic moment-like vector that evolves
+around a magnetic field-like vector that depicts the Hamiltonian of the system.
+In the present work, we demonstrate the geometrical interpretation of neutrino
+in a vacuum in the presence of decay, which transforms this circular trajectory
+of neutrino into a helical track that effectively makes the neutrino system
+mimic a classical damped driven oscillator. We show that in the absence of the
+phase factor $\xi$ in the decay Hamiltonian, the neutrino exactly behaves like
+the system of nuclear magnetic resonance(NMR); however, the inclusion of the
+phase part introduces a $CP$ violation, which makes the system deviate from
+NMR. Finally, we make a qualitative discussion on under-damped,
+critically-damped, and over-damped scenarios geometrically by three different
+diagrams. In the end, we make a comparative study of geometrical picturization
+in vacuum, matter, and decay, which extrapolates the understanding of the
+geometrical representation of neutrino oscillation in a more straightforward
+way.",2312.08178v1
+2024-01-01,Magnon Damping Minimum and Logarithmic Scaling in a Kondo-Heisenberg Model,"Recently, an anomalous temperature evolution of spin wave excitations has
+been observed in a van der Waals metallic ferromagnet Fe$_3$GeTe$_2$ (FGT) [S.
+Bao, et al., Phys. Rev. X 12, 011022 (2022)], whose theoretical understanding
+yet remains elusive. Here we study the spin dynamics of a ferromagnetic
+Kondo-Heisenberg lattice model at finite temperature, and propose a mechanism
+of magnon damping that explains the intriguing experimental results. In
+particular, we find the magnon damping rate $\gamma(T)$ firstly decreases as
+temperature lowers, due to the reduced magnon-magnon scatterings. It then
+reaches a minimum at $T_{\rm d}^*$, and rises up again following a logarithmic
+scaling $\gamma(T) \sim \ln{(T_0/T)}$ (with $T_0$ a constant) for $T < T_{\rm
+d}^*$, which can be attributed to electron-magnon scatterings of spin-flip
+type. Moreover, we obtain the phase diagram containing the ferromagnetic and
+Kondo insulator phases by varying the Kondo coupling, which may be relevant for
+experiments on pressured FGT. The presence of a magnon damping minimum and
+logarithmic scaling at low temperature indicates the emergence of the Kondo
+effect reflected in the collective excitations of local moments in a Kondo
+lattice system.",2401.00758v1
+2024-01-04,Simplified Information Geometry Approach for Massive MIMO-OFDM Channel Estimation -- Part II: Convergence Analysis,"In Part II of this two-part paper, we prove the convergence of the simplified
+information geometry approach (SIGA) proposed in Part I. For a general Bayesian
+inference problem, we first show that the iteration of the common second-order
+natural parameter (SONP) is separated from that of the common first-order
+natural parameter (FONP). Hence, the convergence of the common SONP can be
+checked independently. We show that with the initialization satisfying a
+specific but large range, the common SONP is convergent regardless of the value
+of the damping factor. For the common FONP, we establish a sufficient condition
+of its convergence and prove that the convergence of the common FONP relies on
+the spectral radius of a particular matrix related to the damping factor. We
+give the range of the damping factor that guarantees the convergence in the
+worst case. Further, we determine the range of the damping factor for massive
+MIMO-OFDM channel estimation by using the specific properties of the
+measurement matrices. Simulation results are provided to confirm the
+theoretical results.",2401.02037v1
+2024-01-05,Solving convex optimization problems via a second order dynamical system with implicit Hessian damping and Tikhonov regularization,"This paper deals with a second order dynamical system with a Tikhonov
+regularization term in connection to the minimization problem of a convex
+Fr\'echet differentiable function. The fact that beside the asymptotically
+vanishing damping we also consider an implicit Hessian driven damping in the
+dynamical system under study allows us, via straightforward explicit
+discretization, to obtain inertial algorithms of gradient type. We show that
+the value of the objective function in a generated trajectory converges rapidly
+to the global minimum of the objective function and depending the Tikhonov
+regularization parameter the generated trajectory converges weakly to a
+minimizer of the objective function or the generated trajectory converges
+strongly to the element of minimal norm from the $\argmin$ set of the objective
+function. We also obtain the fast convergence of the velocities towards zero
+and some integral estimates. Our analysis reveals that the Tikhonov
+regularization parameter and the damping parameters are strongly correlated,
+there is a setting of the parameters that separates the cases when weak
+convergence of the trajectories to a minimizer and strong convergence of the
+trajectories to the minimal norm minimizer can be obtained.",2401.02676v1
+2024-01-16,"Influence of temperature, doping, and amorphization on the electronic structure and magnetic damping of iron","Hybrid magnonic quantum systems have drawn increased attention in recent
+years for coherent quantum information processing, but too large magnetic
+damping is a persistent concern when metallic magnets are used. Their intrinsic
+damping is largely determined by electron-magnon scattering induced by
+spin-orbit interactions. In the low scattering limit, damping is dominated by
+intra-band electronic transitions, which has been theoretically shown to be
+proportional to the electronic density of states at the Fermi level. In this
+work, we focus on body-centered-cubic iron as a paradigmatic ferromagnetic
+material. We comprehensively study its electronic structure using
+first-principles density functional theory simulations and account for finite
+lattice temperature, boron (B) doping, and structure amorphization. Our results
+indicate that temperature induced atomic disorder and amorphous atomic
+geometries only have a minor influence. Instead, boron doping noticeably
+decreases the density of states near the Fermi level with an optimal doping
+level of 6.25%. In addition, we show that this reduction varies significantly
+for different atomic geometries and report that the highest reduction
+correlates with a large magnetization of the material. This may suggest
+materials growth under external magnetic fields as a route to explore in
+experiment.",2401.08076v1
+2024-03-13,Effects of wave damping and finite perpendicular scale on three-dimensional Alfvén wave parametric decay in low-beta plasmas,"Shear Alfven wave parametric decay instability (PDI) provides a potential
+path toward significant wave dissipation and plasma heating. However,
+fundamental questions regarding how PDI is excited in a realistic
+three-dimensional (3D) open system and how critically the finite perpendicular
+wave scale -- as found in both the laboratory and space plasmas -- affects the
+excitation remain poorly understood. Here, we present the first 3D,
+open-boundary, hybrid kinetic-fluid simulations of kinetic Alfven wave PDI in
+low-beta plasmas. Key findings are that the PDI excitation is strongly limited
+by the wave damping present, including electron-ion collisional damping
+(represented by a constant resistivity) and geometrical attenuation associated
+with the finite-scale Alfven wave, and ion Landau damping of the child acoustic
+wave. The perpendicular wave scale alone, however, plays no discernible role,
+with different wave scales exhibiting similar instability growth. These
+findings are corroborated by theoretical analysis and estimates. The new
+understanding of 3D kinetic Alfven wave PDI physics is essential for laboratory
+study of the basic plasma process and may also help evaluate the relevance/role
+of PDI in low-beta space plasmas.",2403.08179v1
+2024-03-19,Polarization Dynamics in Paramagnet of Charged Quark-Gluon Plasma,"It is commonly understood that the strong magnetic field produced in heavy
+ion collisions is short-lived. The electric conductivity of the quark-gluon
+plasma is unable to significantly extend the life time of magnetic field. We
+propose an alternative scenario to achieve this: with finite baryon density and
+spin polarization by the initial magnetic field, the quark-gluon plasma behaves
+as a paramagnet, which may continue to polarize quark after fading of initial
+magnetic field. We confirm this picture by calculations in both quantum
+electrodynamics and quantum chromodynamics. In the former case, we find a
+splitting in the damping rates of probe fermion with opposite spin component
+along the magnetic field with the splitting parametrically small than the
+average damping rate. In the latter case, we find a similar splitting in the
+damping rates of probe quark with opposite spin components along the magnetic
+field. The splitting is parametrically comparable to the average damping rate,
+providing an efficient way of polarizing strange quarks by the quark-gluon
+plasma paramagnet consisting of light quarks.",2403.12615v1
+2006-04-14,The UCSD Radio-Selected Quasar Survey for Damped Lyman alpha System,"As large optical quasar surveys for damped Lya become a reality and the study
+of star forming gas in the early Universe achieves statistical robustness, it
+is now vital to identify and quantify the sources of systematic error. Because
+the nature of optically-selected quasar surveys makes them vulnerable to dust
+obscuration, we have undertaken a radio-selected quasar survey for damped Lya
+systems to address this bias. We present the definition and results of this
+survey. We then combine our sample with the CORALS dataset to investigate the
+HI column density distribution function f(N) of damped Lya systems toward
+radio-selected quasars. We find that f(N) is well fit by a power-law f(N) = k_1
+N^alpha_1, with log k_1 = 22.90 and alpha_1 = -2.18. This power-law is in
+excellent agreement with that of optically-selected samples at low N(HI), an
+important yet expected result given that obscuration should have negligible
+effect at these gas columns. However, because of the relatively small size of
+the radio-selected sample, 26 damped Lya systems in 119 quasars, f(N) is not
+well constrained at large N(HI) and the first moment of the HI distribution
+function, Omega_g, is, strictly speaking, a lower limit. The power-law is steep
+enough, however, that extrapolating it to higher column densities implies only
+a modest, logarithmic increase in Omega_g. The radio-selected value of Omega_g
+= 1.15 x 10^-3, agrees well with the results of optically-selected surveys.
+While our results indicate that dust obscuration is likely not a major issue
+for surveys of damped Lya systems, we estimate that a radio-selected sample of
+approximately 100 damped Lya systems will be required to obtain the precision
+necessary to absolutely confirm an absence of dust bias.",0604334v1
+2012-04-12,Evidence of Gunn-Peterson damping wings in high-z quasar spectra: strengthening the case for incomplete reionization,"The spectra of several high-redshift (z>6) quasars have shown evidence for a
+Gunn-Peterson (GP) damping wing, indicating a substantial mean neutral hydrogen
+fraction (x_HI > 0.03) in the z ~ 6 intergalactic medium (IGM). However,
+previous analyses assumed that the IGM was uniformly ionized outside of the
+quasar's HII region. Here we relax this assumption and model patchy
+reionization scenarios for a range of IGM and quasar parameters. We quantify
+the impact of these differences on the inferred x_HI, by fitting the spectra of
+three quasars: SDSS J1148+5251 (z=6.419), J1030+0524 (z=6.308), and J1623+3112
+(z=6.247). We find that the best-fit values of x_HI in the patchy models agree
+well with the uniform case. More importantly, we confirm that the observed
+spectra favor the presence of a GP damping wing, with peak likelihoods
+decreasing by factors of > few - 10 when the spectra are modeled without a
+damping wing. We also find that the Ly alpha absorption spectra, by themselves,
+cannot distinguish the damping wing in a relatively neutral IGM from a damping
+wing in a highly ionized IGM, caused either by an isolated neutral patch, or by
+a damped Ly alpha absorber (DLA). However, neutral patches in a highly ionized
+universe (x_HI < 0.01), and DLAs with the large required column densities (N_HI
+> few x 10^{20} cm^{-2}) are both rare. As a result, when we include reasonable
+prior probabilities for the line of sight (LOS) to intercept either a neutral
+patch or a DLA at the required distance of ~ 40-60 comoving Mpc away from the
+quasar, we find strong lower limits on the neutral fraction in the IGM, x_HI >
+0.1 (at 95% confidence). This strengthens earlier claims that a substantial
+global fraction of hydrogen in the z~6 IGM is in neutral form.",1204.2838v2
+2013-05-31,Highly inclined and eccentric massive planets I: Planet-disc interactions,"In the Solar System, planets have a small inclination with respect to the
+equatorial plane of the Sun, but there is evidence that in extrasolar systems
+the inclination can be very high. This spin-orbit misalignment is unexpected,
+as planets form in a protoplanetary disc supposedly aligned with the stellar
+spin. Planet-planet interactions are supposed to lead to a mutual inclination,
+but the effects of the protoplanetary disc are still unknown. We investigate
+therefore planet-disc interactions for planets above 1M_Jup. We check the
+influence of the inclination i, eccentricity e, and mass M_p of the planet. We
+perform 3D numerical simulations of protoplanetary discs with embedded
+high-mass planets. We provide damping formulae for i and e as a function of i,
+e, and M_p that fit the numerical data. For highly inclined massive planets,
+the gap opening is reduced, and the damping of i occurs on time-scales of the
+order of 10^-4 deg/yr M_disc/(0.01 M_star) with the damping of e on a smaller
+time-scale. While the inclination of low planetary masses (<5M_Jup) is always
+damped, large planetary masses with large i can undergo a Kozai-cycle with the
+disc. These Kozai-cycles are damped in time. Eccentricity is generally damped,
+except for very massive planets (M_p = 5M_Jup) where eccentricity can increase
+for low inclinations. The dynamics tends to a final state: planets end up in
+midplane and can then, over time, increase their eccentricity as a result of
+interactions with the disc. The interactions with the disc lead to damping of i
+and e after a scattering event of high-mass planets. If i is sufficiently
+reduced, the eccentricity can be pumped up because of interactions with the
+disc. If the planet is scattered to high inclination, it can undergo a
+Kozai-cycle with the disc that makes it hard to predict the exact movement of
+the planet and its orbital parameters at the dispersal of the disc.",1305.7330v1
+2014-10-20,Frequency-dependent attenuation and elasticity in unconsolidated earth materials: effect of damping,"We use the Discrete Element Method (DEM) to understand the underlying
+attenuation mechanism in granular media, with special applicability to the
+measurements of the so-called effective mass developed earlier. We consider
+that the particles interact via Hertz-Mindlin elastic contact forces and that
+the damping is describable as a force proportional to the velocity difference
+of contacting grains. We determine the behavior of the complex-valued normal
+mode frequencies using 1) DEM, 2) direct diagonalization of the relevant
+matrix, and 3) a numerical search for the zeros of the relevant determinant.
+All three methods are in strong agreement with each other. The real and the
+imaginary parts of each normal mode frequency characterize the elastic and the
+dissipative properties, respectively, of the granular medium. We demonstrate
+that, as the interparticle damping, $\xi$, increases, the normal modes exhibit
+nearly circular trajectories in the complex frequency plane and that for a
+given value of $\xi$ they all lie on or near a circle of radius $R$ centered on
+the point $-iR$ in the complex plane, where $R\propto 1/\xi$. We show that each
+normal mode becomes critically damped at a value of the damping parameter $\xi
+\approx 1/\omega_n^0$, where $\omega_n^0$ is the (real-valued) frequency when
+there is no damping. The strong indication is that these conclusions carry over
+to the properties of real granular media whose dissipation is dominated by the
+relative motion of contacting grains. For example, compressional or shear waves
+in unconsolidated dry sediments can be expected to become overdamped beyond a
+critical frequency, depending upon the strength of the intergranular damping
+constant.",1410.5484v2
+2020-08-05,Fast optimization via inertial dynamics with closed-loop damping,"In a Hilbert space $H$, in order to develop fast optimization methods, we
+analyze the asymptotic behavior, as time $t$ tends to infinity, of inertial
+continuous dynamics where the damping acts as a closed-loop control. The
+function $f: H \to R$ to be minimized (not necessarily convex) enters the
+dynamic through it gradient, which is assumed to be Lipschitz continuous on the
+bounded subsets of $H$. This gives autonomous dynamical systems with nonlinear
+damping and nonlinear driving force. We first consider the case where the
+damping term $\partial \phi (\dot{x}(t))$ acts as a closed-loop control of the
+velocity. The damping potential $\phi : H \to [0,+\infty)$ is a convex
+continuous function which achieves its minimum at the origin. We show the
+existence and uniqueness of a global solution to the associated Cauchy problem.
+Then, we analyze the asymptotic convergence properties of the generated
+trajectories generated. We use techniques from optimization, control theory,
+and PDE's: Lyapunov analysis based on the decreasing property of an energy-like
+function, quasi-gradient and Kurdyka-Lojasiewicz theory, monotone operator
+theory for wave-like equations. Convergence rates are obtained based on the
+geometric properties of the data $f$ and $\phi$. When $f$ is strongly convex,
+we give general conditions which provide exponential convergence rates. Then,
+we extend the results to the case where an additional Hessian-driven damping
+enters the dynamic, which reduces the oscillations. Finally, we consider an
+inertial system involving jointly the velocity $\dot{x}(t)$ and the gradient
+$\nabla f(x(t))$. In addition to its original results, this work surveys the
+numerous works devoted in recent years to the interaction between continuous
+damped inertial dynamics and numerical algorithms for optimization, with the
+emphasis on autonomous systems, closed-loop adaptive procedures, and
+convergence rates.",2008.02261v3
+2023-01-10,Cosmic Ray Drag and Damping of Compressive Turbulence,"While it is well-known that cosmic rays (CRs) can gain energy from turbulence
+via second order Fermi acceleration, how this energy transfer affects the
+turbulent cascade remains largely unexplored. Here, we show that damping and
+steepening of the compressive turbulent power spectrum are expected once the
+damping time $t_{\rm damp} \sim \rho v^{2}/\dot{E}_{\rm CR} \propto E_{\rm
+CR}^{-1}$ becomes comparable to the turbulent cascade time. Magnetohydrodynamic
+(MHD) simulations of stirred compressive turbulence in a gas-CR fluid with
+diffusive CR transport show clear imprints of CR-induced damping, saturating at
+$\dot{E}_{\rm CR} \sim \tilde{\epsilon}$, where $\tilde{\epsilon}$ is the
+turbulent energy input rate. In that case, almost all the energy in large scale
+motions is absorbed by CRs and does not cascade down to grid scale. Through a
+Hodge-Helmholtz decomposition, we confirm that purely compressive forcing can
+generate significant solenoidal motions, and we find preferential CR damping of
+the compressive component in simulations with diffusion and streaming,
+rendering small-scale turbulence largely solenoidal, with implications for
+thermal instability and proposed resonant scattering of $E > 300$ GeV CRs by
+fast modes. When CR transport is streaming dominated, CRs also damp large scale
+motions, with kinetic energy reduced by up to to an order of magnitude in
+realistic $E_{\rm CR} \sim E_{\rm g}$ scenarios, but turbulence (with a reduced
+amplitude) still cascades down to small scales with the same power spectrum.
+Such large scale damping implies that turbulent velocities obtained from the
+observed velocity dispersion may significantly underestimate turbulent forcing
+rates, i.e. $\tilde{\epsilon} \gg \rho v^{3}/L$.",2301.04156v2
+2024-02-12,"Relaxation of weakly collisional plasma: continuous spectra, Landau eigenmodes, and transition from the collisionless to the fluid limit","The relaxation of a weakly collisional plasma is described by the
+Boltzmann-Poisson equations with the Lenard-Bernstein collision operator. We
+perform a perturbative analysis of these equations, and obtain, for the first
+time, exact analytic solutions, enabling definitive resolutions to
+long-standing controversies regarding the impact of weak collisions on
+continuous spectra and Landau eigenmodes. Unlike some previous studies, we
+retain both damping and diffusion terms in the collision operator. We find that
+the linear response is a temporal convolution of a continuum that depends on
+the continuous velocities of particles, and discrete normal modes that
+encapsulate coherent oscillations. The normal modes are exponentially damped
+over time due to collective effects (Landau damping) as well as collisional
+dissipation. The continuum is also damped by collisions but somewhat
+differently. Up to a collision time, which is the inverse of the collision
+frequency $\nu_{\mathrm{c}}$, the continuum decay is driven by velocity
+diffusion and occurs super-exponentially over a timescale $\sim
+\nu^{-1/3}_{\mathrm{c}}$. After a collision time, however, the continuum decay
+is driven by the collisional damping of particle velocities and diffusion of
+their positions, and occurs exponentially over a timescale $\sim
+\nu_{\mathrm{c}}$. This hitherto unknown, slow exponential decay causes
+perturbations to damp the most on scales comparable to the mean free path, but
+very slowly on larger scales, which establishes the local thermal equilibrium,
+the essence of the fluid limit. The long-term decay of the response is driven
+by the normal modes on scales smaller than the mean free path, but, on larger
+scales, is governed by the slowly decaying continuum and the least damped
+normal mode. Our analysis firmly establishes a long-sought connection between
+the collisionless and fluid limits of weakly collisional plasmas.",2402.07992v1
+2008-06-23,On multi F-nomial coefficients and Inversion formula for F-nomial coefficients,"In response to [6], we discover the looked for inversion formula for F-nomial
+coefficients. Before supplying its proof, we generalize F-nomial coefficients
+to multi F-nomial coefficients and we give their combinatorial interpretation
+in cobweb posets language, as the number of maximal-disjoint blocks of the form
+sP_{k_1,k_2,...,k_s} of layer <Phi_1-->Phi_n>. Then we present inversion
+formula for F-nomial coefficients using multi F-nomial coefficients for all
+cobweb-admissible sequences. To this end we infer also some identities as
+conclusions of that inversion formula for the case of binomial, Gaussian and
+Fibonomial coefficients.",0806.3626v2
+2015-07-06,On the Kendall Correlation Coefficient,"In the present paper, we first discuss the Kendall rank correlation
+coefficient. In continuous case, we define the Kendall rank correlation
+coefficient in terms of the concomitants of order statistics, find the expected
+value of the Kendall rank correlation coefficient and show that the later is
+free of n. We also prove that in continuous case the Kendall correlation
+coefficient converges in probability to its expected value. We then propose to
+consider the expected value of the Kendall rank correlation coefficient as a
+new theoretical correlation coefficient which can be an alternative to the
+classical Pearson product-moment correlation coefficient. At the end of this
+work we analyze illustrative examples.",1507.01427v1
+2017-10-12,The co-Pieri rule for Kronecker coefficients,"A fundamental problem in the representation theory of the symmetric group,
+Sn, is to describe the coefficients in the decomposition of a tensor product of
+two simple representations. These coefficients are known in the literature as
+the Kronecker coefficients. The Littlewood--Richardson coefficients appear as
+an important subfamily of the wider class of stable Kronecker coefficients.
+This subfamily of coefficients can be calculated using a tableaux counting
+algorithm known as the Littlewood--Richardson rule. This paper generalises one
+half of this rule (the ""co-Pieri"" rule) to the the wider family of stable
+Kronecker coefficients.",1710.04523v3
+2023-05-04,All Kronecker coefficients are reduced Kronecker coefficients,"We settle the question of where exactly the reduced Kronecker coefficients
+lie on the spectrum between the Littlewood-Richardson and Kronecker
+coefficients by showing that every Kronecker coefficient of the symmetric group
+is equal to a reduced Kronecker coefficient by an explicit construction. This
+implies the equivalence of a question by Stanley from 2000 and a question by
+Kirillov from 2004 about combinatorial interpretations of these two families of
+coefficients. Moreover, as a corollary, we deduce that deciding the positivity
+of reduced Kronecker coefficients is $NP$-hard, and computing them is
+$\#P$-hard under parsimonious many-one reductions.",2305.03003v1
+1995-09-21,Damped Lyman-alpha and Lyman Limit Absorbers in the Cold Dark Matter Model,"We study the formation of damped \lya and Lyman limit absorbers in a
+hierarchical clustering scenario using a gas dynamical simulation of an $\Omega
+= 1$, cold dark matter universe. In the simulation, these high column density
+systems are associated with forming galaxies. Damped \lya absorption, $N_{HI}
+\simgt 10^{20.2}\cm^{-2}$, arises along lines of sight that pass near the
+centers of relatively massive, dense protogalaxies. Lyman limit absorption,
+$10^{17}\cm^{-2} \simlt N_{HI} \simlt 10^{20.2}\cm^{-2}$, develops on lines of
+sight that pass through the outer parts of such objects or near the centers of
+smaller protogalaxies. The number of Lyman limit systems is less than observed,
+while the number of damped \lya systems is quite close to the observed
+abundance. Damped absorbers are typically $\sim 10$ kpc in radius, but the
+population has a large total cross section because the systems are much more
+numerous than present day $L_*$ galaxies. Our results demonstrate that high
+column density systems like those observed arise naturally in a hierarchical
+theory of galaxy formation and that it is now possible to study these absorbers
+directly from numerical simulations.",9509106v1
+1995-09-21,Nonlinear Damping of Oscillations in Tidal-Capture Binaries,"We calculate the damping of quadrupole f and low order g modes (primary
+modes) by nonlinear coupling to other modes of the star. This damping is orders
+of magnitude more rapid than direct radiative damping when the primary
+amplitude is large, as in tidal capture.
+  Primary modes destabilize high degree g-modes of half their frequency
+(daughter modes) by 3-mode coupling in radiative zones. In sunlike stars, the
+growth time $\equiv\eta^{-1}\approx 4 E_{0,42}^{-1/2}$ days, where $E_{0,42}$
+is the initial energy of the primary mode in units of $10^{42}~$erg, and of
+order $10^{10}E_{0,42}^{5/4}$ daughters are unstable. The growth rate is
+approximately equal to the angular frequency of the primary mode times its
+dimensionless radial amplitude, $\delta R/R_*\approx 0.002E_{0,42}^{1/2}$.
+Although the daughter modes are limited by their own nonlinearities,
+collectively they absorb most of the primary mode's energy after a time $\sim
+10\eta^{-1}$ provided $E_{0}> 10^{40}~\mbox{erg}$. In fact nonlinear mode
+interaction may be the dominant damping process if $E_0\gtrsim
+10^{37}~\mbox{erg}$.
+  Our results have application to tidally captured main sequence globular
+cluster stars of mass $\ge 0.5 M_{\sun}$; the tidal energy is dissipated in the
+radiative core of the star in about a month, which is less than the initial
+orbital period.",9509112v1
+1997-08-12,Spectroscopy of PKS 0528-260: New Limits on CO Absorption and Emission,"We have obtained a moderate resolution spectrum of the quasar PKS 0528-250
+with the Red Channel Spectrograph on the Multiple Mirror Telescope (MMT) in
+order to study a damped Lyman alpha absorption line system at z = 2.8115.
+  We obtain a new upper limit for the CO column density for the z = 2.8108
+velocity component in the z = 2.8115 damped Lyman alpha system. The ionization
+of different species in this component rules out a quasar spectral energy
+distribution (SED) as the ionization field,and implies an ultraviolet radiation
+field intensity a few times that of the Milky Way value. The estimated total
+number density is n(H) about 20 cm^{-3}. The physical size for the z = 2.8108
+component implied by these models is about 40 parsecs. The ionization of
+different species also suggests a structure with a hot intercloud medium
+associated with a H I cloud in this component, that is, most low ionized ions
+are from the cold medium where photoionization and photodissociation dominates.
+The highly ionized species may be from the intercloud medium where collisional
+ionization dominates. We also present newly identified Ni II absorption lines
+in the z = 2.1408 and z = 2.8115 damped Ly$\alpha$ systems. The derived
+depletion of nickel by dust confirms previous results that the dust-to-gas
+ratio in these two damped Lyman alpha systems is about 10% of the Milky Way
+ratio. Millimeter wavelength observations obtained at the NRAO 12 meter
+telescope provide new upper limits on CO (3-2) emission in the z = 2.8115
+damped Lyman alpha system.",9708104v1
+1998-11-04,GMRT Observations of Low z Damped Lyman-alpha Absorbers,"We present Giant Metrewave Radio Telescope (GMRT) observations of redshifted
+HI 21cm absorption in two low redshift (z=0.2212, z=0.0912) damped Lyman-alpha
+systems seen towards the gigahertz peaked source OI 363 (z_em = 0.630). The
+object at z=0.0912 is the lowest redshift damped Lyman-alpha system known to
+date. Ground based imaging (Rao & Turnshek, 1998) shows that at neither
+redshift is there a large spiral galaxy at low impact parameter to the line of
+sight to OI 363, in contradiction with the suggestion that these systems are
+large proto-disks.
+  Since OI 363 is a highly compact, core dominated source, the covering factor
+of the HI gas is likely to be unity. Nonetheless, the spin temperatures derived
+from the 21cm optical depth (and using the N_HI measured from HST spectra, Rao
+& Turnshek, 1998) are high, viz. 1120 +/- 200 K and 825 +/- 110 K for the high
+and low redshift systems respectively. These values are considerably higher
+than typical values (100 - 200 K) measured in our Galaxy and Andromeda and are,
+in fact, similar to those obtained in high redshift damped Lyman-alpha systems.
+Our observations hence suggest that evolutionary effects may not be crucial in
+understanding the difference in derived spin temperature values between local
+spiral disks and high redshift damped Lyman-alpha systems.",9811068v1
+2002-01-25,Galaxies Associated with z~4 Damped Lya Systems: I. Imaging and Photometric Selection,"This paper describes the acquisition and analysis of imaging data for the
+identification of galaxies associated with z~4 damped Lya systems. We present
+deep BRI images of three fields known to contain four z~4 damped systems. We
+discuss the reduction and calibration of the data, detail the color criteria
+used to identify z~4 galaxies, and present a photometric redshift analysis to
+complement the color selection. We have found no galaxy candidates closer to
+the QSO than 7'' which could be responsible for the damped Lya systems.
+Assuming that at least one of the galaxies is not directly beneath the QSO, we
+set an upper limit on this damped Lya system of L < L*/4. Finally, we have
+established a web site to release these imaging data to the public.",0201417v2
+2002-02-25,Eccentricity Evolution for Planets in Gaseous Disks,"We investigate the hypothesis that interactions between a giant planet and
+the disk from which it forms promote eccentricity growth. These interactions
+are concentrated at discrete Lindblad and corotation resonances. Interactions
+at principal Lindblad resonances cause the planet's orbit to migrate and open a
+gap in the disk if the planet is sufficiently massive. Those at first order
+Lindblad and corotation resonances change the planet's orbital eccentricity.
+Eccentricity is excited by interactions at external Lindblad resonances which
+are located on the opposite side of corotation from the planet, and damped by
+co-orbital Lindblad resonances which overlap the planet's orbit. If the planet
+clears a gap in the disk, the rate of eccentricity damping by co-orbital
+Lindblad resonances is reduced. Density gradients associated with the gap
+activate eccentricity damping by corotation resonances at a rate which
+initially marginally exceeds that of eccentricity excitation by external
+Lindblad resonances. But the corotation torque drives a mass flux which reduces
+the density gradient near the resonance. Sufficient partial saturation of
+corotation resonances can tip the balance in favor of eccentricity excitation.
+A minimal initial eccentricity of a few percent is required to overcome viscous
+diffusion which acts to unsaturate corotation resonances by reestablishing the
+large scale density gradient. Thus eccentricity growth is a finite amplitude
+instability. Formally, interactions at the apsidal resonance, which is a
+special kind of co-orbital Lindblad resonance, appears to damp eccentricity
+faster than external Lindblad resonances can excite it. However, apsidal waves
+have such long wavelengths that they do not propagate in protoplanetary disks.
+This reduces eccentricity damping by the apsidal resonance to a modest level.",0202462v1
+2003-07-23,Dusty Molecular Cloud Collapse in the Presence of Alfvén Waves,"It has been shown that magnetic fields play an important role in the
+stability of molecular clouds, mainly perpendicularly to the field direction.
+However, in the parallel direction the stability is a serious problem still to
+be explained. Interstellar turbulence may allow the generation of Alfv\'en
+waves that propagate through the clouds in the magnetic field direction. These
+regions also present great amounts of dust particles which can give rise to new
+wave modes, or modify the pre-existing ones. The dust-cyclotron damping affects
+the Alfv\'en wave propagation near the dust- cyclotron frequency. On the other
+hand, the clouds present different grain sizes, which carry different charges.
+In this sense, a dust particle distribution has several dust-cyclotron
+frequencies and it will affect a broad band of wave frequencies. In this case,
+the energy transfer to the gas is more efficient than in the case where the
+ion-cyclotron damping is considered alone. This effect becomes more important
+if a power law spectrum is considered for the wave energy flux, since the major
+part of the energy is concentrated in low-frequency waves. In this work we
+calculate the dust- cyclotron damping in a dusty and magnetized dwarf molecular
+cloud, as well as determine the changes in the Alfv\'en wave flux. Then, we use
+these results to study the gravitational stability of the cloud. We show that,
+considering the presence of charged dust particles, the wave flux is rapidly
+damped due to dust-cyclotron damping. Then the wave pressure acts in a small
+length scale, and cannot explain the observable cloud sizes, but can explain
+the existence of small and dense cores.",0307411v1
+2005-02-28,Thermal Evolution of a Pulsating Neutron Star,"We have derived a set of equations to describe the thermal evolution of a
+neutron star which undergoes small-amplitude radial pulsations. We have taken
+into account, in the frame of the General Theory of Relativity, the pulsation
+damping due to the bulk and shear viscosity and the accompanying heating of the
+star. The neutrino emission of a pulsating non-superfluid star and its heating
+due to the bulk viscosity are calculated assuming that both processes are
+determined by the non-equilibrium modified Urca process. Analytical and
+numerical solutions to the set of equations of the stellar evolution are
+obtained for linear and strongly non-linear deviations from beta-equilibrium.
+It is shown that a pulsating star may be heated to very high temperatures,
+while the pulsations damp very slowly with time (a power law damping for
+100-1000 years), as long as the damping is determined by the bulk viscosity.
+The contribution of the shear viscosity to the damping becomes important in a
+rather cool star with a low pulsation energy.",0502583v2
+2005-05-02,Collisionless Damping of Fast MHD Waves in Magneto-rotational Winds,"We propose collisionless damping of fast MHD waves as an important mechanism
+for the heating and acceleration of winds from rotating stars. Stellar rotation
+causes magnetic field lines anchored at the surface to form a spiral pattern
+and magneto-rotational winds can be driven. If the structure is a magnetically
+dominated, fast MHD waves generated at the surface can propagate almost
+radially outward and cross the field lines. The propagating waves undergo
+collisionless damping owing to interactions with particles surfing on magnetic
+mirrors that are formed by the waves themselves. The damping is especially
+effective where the angle between the wave propagation and the field lines
+becomes moderately large ($\sim 20$ to $80^{\circ}$). The angle tends naturally
+to increase into this range because the field in magneto-rotational winds
+develops an increasingly large azimuthal component. The dissipation of the wave
+energy produces heating and acceleration of the outflow. We show using
+specified wind structures that this damping process can be important in both
+solar-type stars and massive stars that have moderately large rotation rates.
+This mechanism can play a role in coronae of young solar-type stars which are
+rapidly rotating and show X-ray luminosities much larger than the sun. The
+mechanism could also be important for producing the extended X-ray emitting
+regions inferred to exist in massive stars of spectral type middle B and later.",0505013v5
+2006-08-05,The nature of damped Lyman alpha and sub-damped Lyman alpha absorbers,"We present arguments based on the measured abundances in individual damped
+Lyman alpha systems (DLAs) and sub-damped Lyman alpha systems (sub-DLAs), and
+also the average abundances inferred in large samples of QSO absorption line
+systems, to suggest that the amount of dust in intervening QSO absorbers is
+small and is not responsible for missing many QSOs in magnitude limited QSO
+surveys. While we can not totally rule out a bimodal dust distribution with a
+population of very dusty, metal rich, absorbers which push the background QSOs
+below the observational threshold of current optical spectroscopic studies,
+based upon the current samples it appears that the metallicity in QSO absorbers
+decreases with increase in H I column densities beyond 10^{19} cm^{-2}. Thus
+the sub-DLA population is more metal rich than the DLAs, a trend which may
+possibly extend to the non-damped Lyman limit systems (NDLLS). Based on the
+recently discovered mass-metallicity relation for galaxies, we suggest that
+most sub-DLAs and possibly NDLLS, are associated with massive spiral/elliptical
+galaxies while most DLAs are associated with low mass galaxies. The sub-DLA
+galaxies will then contribute a larger fraction of total mass (stellar and ISM)
+and therefore metals, to the cosmic budget, specially at low redshifts, as
+compared to the DLAs.",0608127v2
+2007-02-12,The Ucsd/Keck Damped Lya Abundance Database: A Decade of High Resolution Spectroscopy,"We publish the Keck/HIRES and Keck/ESI spectra that we have obtained during
+the first 10 years of Keck observatory operations. Our full sample includes 42
+HIRES spectra and 39 ESI spectra along 65 unique sightlines providing abundance
+measurements on ~85 damped Lya systems. The normalized data can be downloaded
+from the journal or from our supporting website:
+http://www.ucolick.org/~xavier/DLA/. The database includes all of the
+sightlines that have been included in our papers on the chemical abundances,
+kinematics, and metallicities of the damped Lya systems. This data has also
+been used to argue for variations in the fine-structure constant. We present
+new chemical abundance measurements for 10 damped Lya systems and a summary
+table of high-resolution metallicity measurements (including values from the
+literature) for 153 damped Lya systems at z>1.6. We caution, however, that this
+metallicity sample (and all previous ones) is biased to higher N(HI) values
+than a random sample.",0702325v1
+1998-06-30,Structure and Spin Dynamics of La$_{0.85}$Sr$_{0.15}$MnO$_3$,"Neutron scattering has been used to study the structure and spin dynamics of
+La$_{0.85}$Sr$_{0.15}$MnO$_3$. The magnetic structure of this system is
+ferromagnetic below T_C = 235 K. We see anomalies in the Bragg peak intensities
+and new superlattice peaks consistent with the onset of a spin-canted phase
+below T_{CA} = 205 K, which appears to be associated with a gap at q = (0, 0,
+0.5) in the spin-wave spectrum. Anomalies in the lattice parameters indicate a
+concomitant lattice distortion. The long-wavelength magnetic excitations are
+found to be conventional spin waves, with a gapless (< 0.02 meV) isotropic
+dispersion relation $E = Dq^2$. The spin stiffness constant D has a $T^{5/2}$
+dependence at low T, and the damping at small q follows $q^4T^{2}$. An
+anomalously strong quasielastic component, however, develops at small wave
+vector above 200 K and dominates the fluctuation spectrum as T -> T_C. At
+larger q, on the other hand, the magnetic excitations become heavily damped at
+low temperatures, indicating that spin waves in this regime are not eigenstates
+of the system, while raising the temperature dramatically increases the
+damping. The strength of the spin-wave damping also depends strongly on the
+symmetry direction in the crystal. These anomalous damping effects are likely
+due to the itinerant character of the $e_g$ electrons.",9806381v1
+2002-08-29,Some notes on ideology of waves in plasmas,"Our last three papers provide an occasion to make some brief notes on
+ideology of waves in plasmas and to rehabilitate Vlasov prescription to
+calculate relevant logarithmically divergent integrals in the principal value
+sense. In this approach asymptotical solutions of plasma oscillations are
+selected according to self-consistent boundary physical conditions. Landau
+damping is absent in this case by definition. Boundary electrical field
+together with conditions of absence of unphysical backward and kinematical
+waves define single-valued dependence of boundary distribution function on
+electron velocity \vec{v} in the case of transversal waves and on the surface
+break of the normal electrical field in the case of longitudinal oscillations.
+We have proposed physically more justified modified iteration procedure of
+collisional damping calculation and demonstrated some results of damping
+decrements calculations in a low-collision electron-ion plasma. Dispersion
+smearing of both longitudinal and transversal high-frequency waves, for which
+the smearing decrement \delta_x is proportional to
+\Delta\omega/(\omega\sqrt{\omega^2-\omega_L^2}), might be the main cause of
+waves amplitude damping in collisionless plasmas imitating Landau damping.",0208098v7
+2007-04-12,The effect of the solar corona on the attenuation of small-amplitude prominence oscillations. I. Longitudinal magnetic field,"Context. One of the typical features shown by observations of solar
+prominence oscillations is that they are damped in time and that the values of
+the damping times are usually between one and three times the corresponding
+oscillatory period. However, the mechanism responsible for the attenuation is
+still not well-known. Aims. Thermal conduction, optically thin or thick
+radiation and heating are taken into account in the energy equation, and their
+role on the attenuation of prominence oscillations is evaluated. Methods. The
+dispersion relation for linear non-adiabatic magnetoacoustic waves is derived
+considering an equilibrium made of a prominence plasma slab embedded in an
+unbounded corona. The magnetic field is orientated along the direction parallel
+to the slab axis and has the same strength in all regions. By solving the
+dispersion relation for a fixed wavenumber, a complex oscillatory frequency is
+obtained, and the period and the damping time are computed. Results. The effect
+of conduction and radiation losses is different for each magnetoacoustic mode
+and depends on the wavenumber. In the observed range of wavelengths the
+internal slow mode is attenuated by radiation from the prominence plasma, the
+fast mode by the combination of prominence radiation and coronal conduction and
+the external slow mode by coronal conduction. The consideration of the external
+corona is of paramount importance in the case of the fast and external slow
+modes, whereas it does not affect the internal slow modes at all. Conclusions.
+Non-adiabatic effects are efficient damping mechanisms for magnetoacoustic
+modes, and the values of the obtained damping times are compatible with those
+observed.",0704.1566v2
+2007-10-01,Lyman-alpha Damping Wing Constraints on Inhomogeneous Reionization,"One well-known way to constrain the hydrogen neutral fraction, x_H, of the
+high-redshift intergalactic medium (IGM) is through the shape of the red
+damping wing of the Lya absorption line. We examine this method's effectiveness
+in light of recent models showing that the IGM neutral fraction is highly
+inhomogeneous on large scales during reionization. Using both analytic models
+and ""semi-numeric"" simulations, we show that the ""picket-fence"" absorption
+typical in reionization models introduces both scatter and a systematic bias to
+the measurement of x_H. In particular, we show that simple fits to the damping
+wing tend to overestimate the true neutral fraction in a partially ionized
+universe, with a fractional error of ~ 30% near the middle of reionization.
+This bias is generic to any inhomogeneous model. However, the bias is reduced
+and can even underestimate x_H if the observational sample only probes a subset
+of the entire halo population, such as quasars with large HII regions. We also
+find that the damping wing absorption profile is generally steeper than one
+would naively expect in a homogeneously ionized universe. The profile steepens
+and the sightline-to-sightline scatter increases as reionization progresses. Of
+course, the bias and scatter also depend on x_H and so can, at least in
+principle, be used to constrain it. Damping wing constraints must therefore be
+interpreted by comparison to theoretical models of inhomogeneous reionization.",0710.0371v1
+2008-02-11,Eccentricity of masing disks in Active Galactic Nuclei,"Observations of Keplerian disks of masers in NCG 4258 and other Seyfert
+galaxies can be used to obtain geometric distance estimates and derive the
+Hubble constant. The ultimate precision of such measurements could be limited
+by uncertainties in the disk geometry. Using a time-dependent linear theory
+model, we study the evolution of a thin initially eccentric disk under
+conditions appropriate to sub-pc scales in Active Galactic Nuclei. The
+evolution is controlled by a combination of differential precession driven by
+the disk potential and propagating eccentricity waves that are damped by
+viscosity. A simple estimate yields a circularization timescale of
+approximately 10 Myr at 0.1 pc. Numerical solutions for the eccentricity
+evolution confirm that damping commences on this timescale, but show that the
+subsequent decay rate of the eccentricity depends upon the uncertain strength
+of viscous damping of eccentricity. If eccentricity waves are important further
+decay of the eccentricity can be slow, with full circularization requiring up
+to 50 Myr for disks at radii of 0.1 pc to 0.2 pc. Observationally, this implies
+that it is plausible that enough time has elapsed for the eccentricity of
+masing disks to have been substantially damped, but that it may not be
+justified to assume vanishing eccentricity. We predict that during the damping
+phase the pericenter of the eccentric orbits describes a moderately tightly
+wound spiral with radius.",0802.1524v1
+2008-02-20,The Effect of Charon's Tidal Damping on the Orbits of Pluto's Three Moons,"Pluto's recently discovered minor moons, Nix and Hydra, have almost circular
+orbits, and are nearly coplanar with Charon, Pluto's major moon. This is
+surprising because tidal interactions with Pluto are too weak to damp their
+eccentricities. We consider an alternative possibility: that Nix and Hydra
+circularize their orbits by exciting Charon's eccentricity via secular
+interactions, and Charon in turn damps its own eccentricity by tidal
+interaction with Pluto. The timescale for this process can be less than the age
+of the Solar System, for plausible tidal parameters and moon masses. However,
+as we show numerically and analytically, the effects of the 2:1 and 3:1
+resonant forcing terms between Nix and Charon complicate this picture. In the
+presence of Charon's tidal damping, the 2:1 term forces Nix to migrate outward
+and the 3:1 term changes the eccentricity damping rate, sometimes leading to
+eccentricity growth. We conclude that this mechanism probably does not explain
+Nix and Hydra's current orbits. Instead, we suggest that they were formed
+in-situ with low eccentricities.
+  We also show that an upper limit on Nix's migration speed sets a lower limit
+on Pluto-Charon's tidal circularization timescale of >10^5 yrs. Moreover,
+Hydra's observed proper eccentricity may be explained by the 3:2 forcing by
+Nix.",0802.2939v1
+2008-03-18,Non-adiabatic magnetohydrodynamic waves in a cylindrical prominence thread with mass flow,"High-resolution observations show that oscillations and waves in prominence
+threads are common and that they are attenuated in a few periods. In addition,
+observers have also reported the presence of material flows in such prominence
+fine-structures. Here we investigate the time damping of non-leaky oscillations
+supported by a homogeneous cylindrical prominence thread embedded in an
+unbounded corona and with a steady mass flow. Thermal conduction and radiative
+losses are taken into account as damping mechanisms, and the effect of these
+non-ideal effects and the steady flow on the attenuation of oscillations is
+assessed. We solve the general dispersion relation for linear, non-adiabatic
+magnetoacoustic and thermal waves supported by the model, and find that slow
+and thermal modes are efficiently attenuated by non-adiabatic mechanisms. On
+the contrary, fast kink modes are much less affected and their damping times
+are much larger than those observed. The presence of flow has no effect on the
+damping of slow and thermal waves, whereas fast kink waves are more (less)
+attenuated when they propagate parallel (anti-parallel) to the flow direction.
+Although the presence of steady mass flows improves the efficiency of
+non-adiabatic mechanisms on the attenuation of transverse, kink oscillations
+for parallel propagation to the flow, its effect is still not enough to obtain
+damping times compatible with observations.",0803.2600v2
+2008-07-28,"Thermal fluctuations in moderately damped Josephson junctions: Multiple escape and retrapping, switching- and return-current distributions and hysteresis","A crossover at a temperature T* in the temperature dependence of the width s
+of the distribution of switching currents of moderately damped Josephson
+junctions has been reported in a number of recent publications, with positive
+ds/dT and IV characteristics associated with underdamped behaviour for lower
+temperatures T<T*, and negative ds/dT and IV characteristics resembling
+overdamped behaviour for higher temperatures T>T*. We have investigated in
+detail the behaviour of Josephson junctions around the temperature T* by using
+Monte Carlo simulations including retrapping from the running state into the
+supercurrent state as given by the model of Ben-Jacob et al. We develop
+discussion of the important role of multiple escape and retrapping events in
+the moderate-damping regime, in particular considering the behaviour in the
+region close to T*. We show that the behaviour is more fully understood by
+considering two crossover temperatures, and that the shape of the distribution
+and s(T) around T*, as well as at lower T<T*, are largely determined by the
+shape of the conventional thermally activated switching distribution. We show
+that the characteristic temperatures T* are not unique for a particular
+Josephson junction, but have some dependence on the ramp rate of the applied
+bias current. We also consider hysteresis in moderately damped Josephson
+junctions and discuss the less commonly measured distribution of return
+currents for a decreasing current ramp. We find that some hysteresis should be
+expected to persist above T* and we highlight the importance, even well below
+T*, of accounting properly for thermal fluctuations when determining the
+damping parameter Q.",0807.4502v1
+2009-02-26,Viscous propagation of mass flow variability in accretion discs,"We study mass flow rate through a disc resulting from a varying mass supply
+rate. Variable mass supply rate occurs, e.g., during disc state transitions,
+and in interacting eccentric binaries. It is, however, damped by the viscosity
+of the disc. Here, we calculate this damping in detail. We derive an analytical
+description of the propagation of the flow rate using the solution of
+Lynden-Bell & Pringle, in which the disc is assumed to extend to infinity. In
+particular, we derive the accretion-rate Green's function, and its Fourier
+transform, which gives the fractional damping at a given variability frequency.
+We then compare this model to that of a finite disc with the mass supply at its
+outer edge. We find significant differences with respect to the infinite disc
+solution, which we find to overestimate the viscous damping. In particular, the
+asymptotic form of the Green's function is power-law for the infinite disc and
+exponential for the finite one. We then find a simple fitting form for the
+latter, and also calculate its Fourier transform. In general, the damping
+becomes very strong when the viscous time at the outer edge of the disc becomes
+longer than the modulation time scale. We apply our results to a number of
+astrophysical systems. We find the effect is much stronger in low-mass X-ray
+binaries, where the disc size is comparable to that of the Roche lobe, than in
+high-mass binaries, where the wind-fed disc can have a much smaller size.",0902.4530v2
+2010-04-09,Oscillations of weakly viscous conducting liquid drops in a strong magnetic field,"We analyse small-amplitude oscillations of a weakly viscous electrically
+conducting liquid drop in a strong uniform DC magnetic field. An asymptotic
+solution is obtained showing that the magnetic field does not affect the shape
+eigenmodes, which remain the spherical harmonics as in the non-magnetic case.
+Strong magnetic field, however, constrains the liquid flow associated with the
+oscillations and, thus, reduces the oscillation frequencies by increasing
+effective inertia of the liquid. In such a field, liquid oscillates in a
+two-dimensional (2D) way as solid columns aligned with the field. Two types of
+oscillations are possible: longitudinal and transversal to the field. Such
+oscillations are weakly damped by a strong magnetic field - the stronger the
+field, the weaker the damping, except for the axisymmetric transversal and
+inherently 2D modes. The former are overdamped because of being incompatible
+with the incompressibility constraint, whereas the latter are not affected at
+all because of being naturally invariant along the field. Since the magnetic
+damping for all other modes decreases inversely with the square of the field
+strength, viscous damping may become important in a sufficiently strong
+magnetic field. The viscous damping is found analytically by a simple energy
+dissipation approach which is shown for the longitudinal modes to be equivalent
+to a much more complicated eigenvalue perturbation technique. This study
+provides a theoretical basis for the development of new measurement methods of
+surface tension, viscosity and the electrical conductivity of liquid metals
+using the oscillating drop technique in a strong superimposed DC magnetic
+field.",1004.1548v2
+2011-02-03,Damping of Electron Density Structures and Implications for Interstellar Scintillation,"The forms of electron density structures in kinetic Alfven wave turbulence
+are studied in connection with scintillation. The focus is on small scales $L
+\sim 10^8-10^{10}$ cm where the Kinetic Alfv\'en wave (KAW) regime is active in
+the interstellar medium. MHD turbulence converts to a KAW cascade, starting at
+10 times the ion gyroradius and continuing to smaller scales. These scales are
+inferred to dominate scintillation in the theory of Boldyrev et al. From
+numerical solutions of a decaying kinetic Alfv\'en wave turbulence model,
+structure morphology reveals two types of localized structures, filaments and
+sheets, and shows that they arise in different regimes of resistive and
+diffusive damping. Minimal resistive damping yields localized current filaments
+that form out of Gaussian-distributed initial conditions. When resistive
+damping is large relative to diffusive damping, sheet-like structures form. In
+the filamentary regime, each filament is associated with a non-localized
+magnetic and density structure, circularly symmetric in cross section. Density
+and magnetic fields have Gaussian statistics (as inferred from Gaussian-valued
+kurtosis) while density gradients are strongly non-Gaussian, more so than
+current. This enhancement of non-Gaussian statistics in a derivative field is
+expected since gradient operations enhance small-scale fluctuations. The
+enhancement of density gradient kurtosis over current kurtosis is not obvious,
+yet it suggests that modest fluctuation levels in electron density may yield
+large scintillation events during pulsar signal propagation in the interstellar
+medium. In the sheet regime the same statistical observations hold, despite the
+absence of localized filamentary structures. Probability density functions are
+constructed from statistical ensembles in both regimes, showing clear formation
+of long, highly non-Gaussian tails.",1102.0810v2
+2011-09-28,"Different dimensionality trends in the Landau damping of magnons in iron, cobalt and nickel: time dependent density functional study","We study the Landau damping of ferromagnetic magnons in Fe, Co, and Ni as the
+dimensionality of the system is reduced from three to two. We resort to the
+\textit{ab initio} linear response time dependent density functional theory in
+the adiabatic local spin density approximation. The numerical scheme is based
+on the Korringa-Kohn-Rostoker Green's function method. The key points of the
+theoretical approach and the implementation are discussed. We investigate the
+transition metals in three different forms: bulk phases, free-standing thin
+films and thin films supported on a nonmagnetic substrate. We demonstrate that
+the dimensionality trends in Fe and Ni are opposite: in Fe the transition from
+bulk bcc crystal to Fe/Cu(100) film reduces the damping whereas in Ni/Cu(100)
+film the attenuation increases compared to bulk fcc Ni. In Co, the strength of
+the damping depends relatively weakly on the sample dimensionality. We explain
+the difference in the trends on the basis of the underlying electronic
+structure. The influence of the substrate on the spin-wave damping is analyzed
+by employing Landau maps representing wave-vector resolved spectral density of
+the Stoner excitations.",1109.6217v2
+2011-10-06,Dissipative and conservative nonlinearity in carbon nanotube and graphene mechanical resonators,"Graphene and carbon nanotubes represent the ultimate size limit of one and
+two-dimensional nanoelectromechanical resonators. Because of their reduced
+dimensionality, graphene and carbon nanotubes display unusual mechanical
+behavior; in particular, their dynamics is highly nonlinear. Here, we review
+several types of nonlinear behavior in resonators made from nanotubes and
+graphene. We first discuss an unprecedented scenario where damping is described
+by a nonlinear force. This scenario is supported by several experimental facts:
+(i) the quality factor varies with the amplitude of the motion as a power law
+whose exponent coincides with the value predicted by the nonlinear damping
+model, (ii) hysteretic behavior (of the motional amplitude as a function of
+driving frequency) is absent in some of our resonators even for large driving
+forces, as expected when nonlinear damping forces are large, and (iii) when we
+quantify the linear damping force (by performing parametric excitation
+measurements) we find that it is significantly smaller than the nonlinear
+damping force. We then review parametric excitation measurements, an
+alternative actuation method which is based on nonlinear dynamics. Finally, we
+discuss experiments where the mechanical motion is coupled to electron
+transport through a nanotube. The coupling can be made so strong that the
+associated force acting on the nanotube becomes highly nonlinear with
+displacement and velocity. Overall, graphene and nanotube resonators hold
+promise for future studies on classical and quantum nonlinear dynamics.",1110.1234v1
+2012-06-02,Slow Mode Oscillations and Damping of Hot Solar Coronal Loops,"The effect of temperature inhomogeneity on the periods, their ratios
+(fundamental vs. first overtone), and the damping times of the standing slow
+modes in gravitationally stratified solar coronal loops are studied. The
+effects of optically thin radiation, compressive viscosity, and thermal
+conduction are considered. The linearized one-dimensional magnetohydrodynamic
+(MHD) equations (under low-$\beta$ condition) were reduced to a fourth--order
+ordinary differential equation for the perturbed velocity. The numerical
+results indicate that the periods of non-isothermal loops (i.e. temperature
+increases from the loop base to apex) are smaller compared to those of
+isothermal loops. In the presence of radiation, viscosity, and thermal
+conduction, an increase in the temperature gradient is followed by a monotonic
+decrease in the periods (compared with the isothermal case), while the period
+ratio turns out to be a sensitive function of the gradient of the temperature
+and the loop lengths. We verify that radiative dissipation is not a main
+cooling mechanism of both isothermal and non-isothermal hot coronal loops and
+has a small effect on the periods. Thermal conduction and compressive viscosity
+are primary mechanisms in the damping of slow modes of the hot coronal loops.
+The periods and damping times in the presence of compressive viscosity and/or
+thermal conduction dissipation are consistent with the observed data in
+specific cases. By tuning the dissipation parameters, the periods and the
+damping times could be made consistent with the observations in more general
+cases.",1206.0366v1
+2012-09-15,Damped kink oscillations of flowing prominence threads,"Transverse oscillations of thin threads in solar prominences are frequently
+reported in high-resolution observations. Two typical features of the
+observations are that the oscillations are damped in time and that simultaneous
+mass flows along the threads are detected. Flows cause the dense threads to
+move along the prominence magnetic structure while the threads are oscillating.
+The oscillations have been interpreted in terms of standing magnetohydrodynamic
+(MHD) kink waves of the magnetic flux tubes which support the threads. The
+damping is most likely due to resonant absorption caused by plasma
+inhomogeneity. The technique of seismology uses the observations combined with
+MHD wave theory to estimate prominence physical parameters. This paper presents
+a theoretical study of the joint effect of flow and resonant absorption on the
+amplitude of standing kink waves in prominence threads. We find that flow and
+resonant absorption can either be competing effects on the amplitude or both
+can contribute to damp the oscillations depending on the instantaneous position
+of the thread within the prominence magnetic structure. The amplitude profile
+deviates from the classic exponential profile of resonantly damped kink waves
+in static flux tubes. Flow also introduces a progressive shift of the
+oscillation period compared to the static case, although this effect is in
+general of minor importance. We test the robustness of seismological estimates
+by using synthetic data aiming to mimic real observations. The effect of the
+thread flow can significantly affect the estimation of the transverse
+inhomogeneity length scale. The presence of random background noise adds
+uncertainty to this estimation. Caution needs to be paid to the seismological
+estimates that do not take the influence of flow into account.",1209.3382v1
+2013-04-13,Parametric survey of longitudinal prominence oscillation simulations,"It is found that both microflare-sized impulsive heating at one leg of the
+loop and a suddenly imposed velocity perturbation can propel the prominence to
+oscillate along the magnetic dip. An extensive parameter survey results in a
+scaling law, showing that the period of the oscillation, which weakly depends
+on the length and height of the prominence, and the amplitude of the
+perturbations, scales with $\sqrt{R/g_\odot}$, where $R$ represents the
+curvature radius of the dip, and $g_\odot$ is the gravitational acceleration of
+the Sun. This is consistent with the linear theory of a pendulum, which implies
+that the field-aligned component of gravity is the main restoring force for the
+prominence longitudinal oscillations, as confirmed by the force analysis.
+However, the gas pressure gradient becomes non-negligible for short
+prominences. The oscillation damps with time in the presence of non-adiabatic
+processes. Compared to heat conduction, the radiative cooling is the dominant
+factor leading to the damping. A scaling law for the damping timescale is
+derived, i.e., $\tau\sim l^{1.63} D^{0.66}w^{-1.21}v_{0}^{-0.30}$, showing
+strong dependence on the prominence length $l$, the geometry of the magnetic
+dip (characterized by the depth $D$ and the width $w$), and the velocity
+perturbation amplitude $v_0$. The larger the amplitude, the faster the
+oscillation damps. It is also found that mass drainage significantly reduces
+the damping timescale when the perturbation is too strong.",1304.3798v1
+2013-06-08,Observation of a Berry phase anti-damping spin-orbit torque,"Recent observations of current-induced magnetization switching at
+ferromagnet/normal-conductor interfaces have important consequences for future
+magnetic memory technology. In one interpretation, the switching originates
+from carriers with spin-dependent scattering giving rise to a relativistic
+anti-damping spin-orbit torque (SOT) in structures with broken space-inversion
+symmetry. The alternative interpretation combines the relativistic spin Hall
+effect (SHE), making the normal-conductor an injector of a spin-current, with
+the non-relativistic spin-transfer torque (STT) in the ferromagnet. Remarkably,
+the SHE in these experiments originates from the Berry phase effect in the band
+structure of a clean crystal and the anti-damping STT is also based on a
+disorder-independent transfer of spin from carriers to magnetization. Here we
+report the observation of an anti-damping SOT stemming from an analogous Berry
+phase effect to the SHE. The SOT alone can therefore induce magnetization
+dynamics based on a scattering-independent principle. The ferromagnetic
+semiconductor (Ga,Mn)As we use has a broken space-inversion symmetry in the
+crystal. This allows us to consider a bare ferromagnetic element which
+eliminates by design any SHE related contribution to the spin torque. We
+provide an intuitive picture of the Berry phase origin of the anti-damping SOT
+and a microscopic modeling of measured data.",1306.1893v1
+2013-08-20,Stringent constraints on the H I spin temperature in two z > 3 Damped Lyman-alpha systems from redshifted 21 cm absorption studies,"Physical properties of Damped Lyman-alpha absorbers and their evolution are
+closely related to galaxy formation and evolution theories, and have important
+cosmological implications. H I 21 cm absorption study is one useful way of
+measuring the temperature of these systems. In this work, very strong
+constraints on the temperature of two Damped Lyman-alpha absorbers at z > 3 are
+derived from low radio frequency observations. The H I spin temperature is
+found to be greater than 2000 K for both the absorbers. The high spin
+temperature of these high-redshift systems is in agreement with the trend found
+in a compilation of temperatures for other Damped Lyman-alpha absorbers. We
+also argue that the temperature - metallicity relation, reported earlier in the
+literature, is unlikely to be a spurious line of sight effect, and that the
+redshift evolution of the spin temperature does not arises due to a selection
+effect. All of these are consistent with a redshift evolution of the warm gas
+fraction in Damped Lyman-alpha systems.",1308.4410v1
+2013-09-26,Non-Landau damping of magnetic excitations in systems with localized and itinerant electrons,"We discuss the form of the damping of magnetic excitations in a metal near a
+ferromagnetic instability. The paramagnon theory predicts that the damping term
+should have the form $\Omega/\Gamma (q)$ with $\Gamma (q) \propto q$ (the
+Landau damping). However, the experiments on uranium metallic compounds UGe$_2$
+and UCoGe showed that $\Gamma (q)$ tends to a constant value at vanishing $q$.
+A non-zero $\Gamma (0)$ is impossible in systems with one type of carriers
+(either localized or itinerant) because it would violate the spin conservation.
+It has been conjectured recently that a non-zero $\Gamma (q)$ in UGe$_2$ and
+UCoGe may be due to the presence of both localized and itinerant electrons in
+these materials, with ferromagnetism involving predominantly localized spins.
+We present microscopic analysis of the damping of near-critical localized
+excitations due to interaction with itinerant carriers. We show explicitly how
+the presence of two types of electrons breaks the cancellation between the
+contributions to $\Gamma (0)$ from self-energy and vertex correction insertions
+into the spin polarization bubble and discuss the special role of the
+Aslamazov-Larkin processes. We show that $\Gamma (0)$ increases with $T$ both
+in the paramagnetic and ferromagnetic regions, but in-between it has a peak at
+$T_c$. We compare our theory with the available experimental data.",1309.7065v3
+2014-06-16,Design of the Readout Electronics for the Qualification Model of DAMPE BGO Calorimeter,"The DAMPE (DArk Matter Particle Explorer) is a scientific satellite being
+developed in China, aimed at cosmic ray study, gamma ray astronomy, and
+searching for the clue of dark matter particles, with a planned mission period
+of more than 3 years and an orbit altitude of about 500 km. The BGO
+Calorimeter, which consists of 308 BGO (Bismuth Germanate Oxid) crystal bars,
+616 PMTs (photomultiplier tubes) and 1848 dynode signals, has approximately 32
+radiation lengths. It is a crucial sub-detector of the DAMPE payload, with the
+functions of precisely measuring the energy of cosmic particles from 5 GeV to
+10TeV, distinguishing positrons/electrons and gamma rays from hadron
+background, and providing trigger information for the whole DAMPE payload. The
+dynamic range for a single BGO crystal is about 2?105 and there are 1848
+detector signals in total. To build such an instrument in space, the major
+design challenges for the readout electronics come from the large dynamic
+range, the high integrity inside the very compact structure, the strict power
+supply budget and the long term reliability to survive the hush environment
+during launch and in orbit. Currently the DAMPE mission is in the end of QM
+(Qualification Model) stage. This paper presents a detailed description of the
+readout electronics for the BGO calorimeter.",1406.3886v1
+2015-04-17,Chiral damping of magnetic domain walls,"Structural symmetry breaking in magnetic materials is responsible for a
+variety of outstanding physical phenomena. Examples range from the existence of
+multiferroics, to current induced spin orbit torques (SOT) and the formation of
+topological magnetic structures. In this letter we bring into light a novel
+effect of the structural inversion asymmetry (SIA): a chiral damping mechanism.
+This phenomenon is evidenced by measuring the field driven domain wall (DW)
+motion in perpendicularly magnetized asymmetric Pt/Co/Pt trilayers. The
+difficulty in evidencing the chiral damping is that the ensuing DW dynamics
+exhibit identical spatial symmetry to those expected from the
+Dzyaloshinskii-Moriya interaction (DMI). Despite this fundamental resemblance,
+the two scenarios are differentiated by their time reversal properties: while
+DMI is a conservative effect that can be modeled by an effective field, the
+chiral damping is purely dissipative and has no influence on the equilibrium
+magnetic texture. When the DW motion is modulated by an in-plane magnetic
+field, it reveals the structure of the internal fields experienced by the DWs,
+allowing to distinguish the physical mechanism. The observation of the chiral
+damping, not only enriches the spectrum of physical phenomena engendered by the
+SIA, but since it can coexists with DMI it is essential for conceiving DW and
+skyrmion devices.",1504.04411v1
+2015-07-28,Spatial damping of propagating sausage waves in coronal cylinders,"Sausage modes are important in coronal seismology. Spatially damped
+propagating sausage waves were recently observed in the solar atmosphere. We
+examine how wave leakage influences the spatial damping of sausage waves
+propagating along coronal structures modeled by a cylindrical density
+enhancement embedded in a uniform magnetic field. Working in the framework of
+cold magnetohydrodynamics, we solve the dispersion relation (DR) governing
+sausage waves for complex-valued longitudinal wavenumber $k$ at given real
+angular frequencies $\omega$. For validation purposes, we also provide
+analytical approximations to the DR in the low-frequency limit and in the
+vicinity of $\omega_{\rm c}$, the critical angular frequency separating trapped
+from leaky waves. In contrast to the standing case, propagating sausage waves
+are allowed for $\omega$ much lower than $\omega_{\rm c}$. However, while able
+to direct their energy upwards, these low-frequency waves are subject to
+substantial spatial attenuation. The spatial damping length shows little
+dependence on the density contrast between the cylinder and its surroundings,
+and depends only weakly on frequency. This spatial damping length is of the
+order of the cylinder radius for $\omega \lesssim 1.5 v_{\rm Ai}/a$, where $a$
+and $v_{\rm Ai}$ are the cylinder radius and the Alfv\'en speed in the
+cylinder, respectively. We conclude that if a coronal cylinder is perturbed by
+symmetric boundary drivers (e.g., granular motions) with a broadband spectrum,
+wave leakage efficiently filters out the low-frequency components.",1507.07724v1
+2015-10-19,On the branching of the quasinormal resonances of near-extremal Kerr black holes,"It has recently been shown by Yang. et. al. [Phys. Rev. D {\bf 87}, 041502(R)
+(2013)] that rotating Kerr black holes are characterized by two distinct sets
+of quasinormal resonances. These two families of quasinormal resonances display
+qualitatively different asymptotic behaviors in the extremal ($a/M\to 1$)
+black-hole limit: The zero-damping modes (ZDMs) are characterized by relaxation
+times which tend to infinity in the extremal black-hole limit ($\Im\omega\to 0$
+as $a/M\to 1$), whereas the damped modes (DMs) are characterized by non-zero
+damping rates ($\Im\omega\to$ finite-values as $a/M\to 1$). In this paper we
+refute the claim made by Yang et. al. that co-rotating DMs of near-extremal
+black holes are restricted to the limited range $0\leq
+\mu\lesssim\mu_{\text{c}}\approx 0.74$, where $\mu\equiv m/l$ is the
+dimensionless ratio between the azimuthal harmonic index $m$ and the spheroidal
+harmonic index $l$ of the perturbation mode. In particular, we use an
+analytical formula originally derived by Detweiler in order to prove the
+existence of DMs (damped quasinormal resonances which are characterized by
+finite $\Im\omega$ values in the $a/M\to 1$ limit) of near-extremal black holes
+in the $\mu>\mu_{\text{c}}$ regime, the regime which was claimed by Yang et.
+al. not to contain damped modes. We show that these co-rotating DMs (in the
+regime $\mu>\mu_{\text{c}}$) are expected to characterize the resonance spectra
+of rapidly-rotating (near-extremal) black holes with $a/M\gtrsim 1-10^{-9}$.",1510.05604v1
+2016-02-16,Damping and power spectra of quasi-periodic intensity disturbances above a solar polar coronal hole,"We study intensity disturbances above a solar polar coronal hole seen in the
+AIA 171 \AA\ and 193 \AA\ passbands, aiming to provide more insights into their
+physical nature. The damping and power spectra of the intensity disturbances
+with frequencies from 0.07 mHz to 10.5 mHz are investigated. The damping of the
+intensity disturbances tends to be stronger at lower frequencies, and their
+damping behavior below 980"" (for comparison, the limb is at 945"") is different
+from what happens above. No significant difference is found between the damping
+of the intensity disturbances in the AIA 171 \AA\ and that in the AIA 193 \AA.
+The indices of the power spectra of the intensity disturbances are found to be
+slightly smaller in the AIA 171 \AA\ than in the AIA 193 \AA, but the
+difference is within one sigma deviation. An additional enhanced component is
+present in the power spectra in a period range of 8--40 minutes at lower
+heights. While the power spectra of spicule is highly correlated with its
+associated intensity disturbance, it suggests that the power spectra of the
+intensity disturbances might be a mixture of spicules and wave activities. We
+suggest that each intensity disturbance in the polar coronal hole is possibly a
+series of independent slow magnetoacoustic waves triggered by spicular
+activities.",1602.04883v1
+2016-04-20,Nonlinear wave damping due to multi-plasmon resonances,"For short wavelengths, it is well known that the linearized Wigner-Moyal
+equation predicts wave damping due to wave-particle interaction, where the
+resonant velocity shifted from the phase velocity by a velocity $v_q = \hbar
+k/2m$. Here $\hbar$ is the reduced Planck constant, $k$ is the wavenumber and
+$m$ is the electron mass. Going beyond linear theory, we find additional
+resonances with velocity shifts $n v_q$, $n = 2, 3, \ldots$, giving rise to a
+new wave-damping mechanism that we term \emph{multi-plasmon damping}, as it can
+be seen as the simultaneous absorption (or emission) of multiple plasmon
+quanta. Naturally this wave damping is not present in classical plasmas. For a
+temperature well below the Fermi temperature, if the linear ($n = 1$) resonant
+velocity is outside the Fermi sphere, the number of linearly resonant particles
+is exponentially small, while the multi-plasmon resonances can be located in
+the bulk of the distribution. We derive sets of evolution equations for the
+case of two-plasmon and three-plasmon resonances for Langmuir waves in the
+simplest case of a fully degenerate plasma. By solving these equations
+numerically for a range of wave-numbers we find the corresponding damping
+rates, and we compare them to results from linear theory to estimate the
+applicability. Finally, we discuss the effects due to a finite temperature.",1604.05983v2
+2016-05-09,Storage-ring Electron Cooler for Relativistic Ion Beams,"Application of electron cooling at ion energies above a few GeV has been
+limited due to reduction of electron cooling efficiency with energy and
+difficulty in producing and accelerating a high-current high-quality electron
+beam. A high-current storage-ring electron cooler offers a solution to both of
+these problems by maintaining high cooling beam quality through
+naturally-occurring synchrotron radiation damping of the electron beam.
+However, the range of ion energies where storage-ring electron cooling can be
+used has been limited by low electron beam damping rates at low ion energies
+and high equilibrium electron energy spread at high ion energies. This paper
+reports a development of a storage ring based cooler consisting of two sections
+with significantly different energies: the cooling and damping sections. The
+electron energy and other parameters in the cooling section are adjusted for
+optimum cooling of a stored ion beam. The beam parameters in the damping
+section are adjusted for optimum damping of the electron beam. The necessary
+energy difference is provided by an energy recovering SRF structure. A
+prototype linear optics of such storage-ring cooler and initial tracking
+simulations are presented and some potential issues such as coherent
+synchrotron radiation and beam break up are discussed.",1605.02594v1
+2016-07-06,Measuring Collisionless Damping in Heliospheric Plasmas using Field-Particle Correlations,"An innovative field-particle correlation technique is proposed that uses
+single-point measurements of the electromagnetic fields and particle velocity
+distribution functions to investigate the net transfer of energy from fields to
+particles associated with the collisionless damping of turbulent fluctuations
+in weakly collisional plasmas, such as the solar wind. In addition to providing
+a direct estimate of the local rate of energy transfer between fields and
+particles, it provides vital new information about the distribution of that
+energy transfer in velocity space. This velocity-space signature can
+potentially be used to identify the dominant collisionless mechanism
+responsible for the damping of turbulent fluctuations in the solar wind. The
+application of this novel field-particle correlation technique is illustrated
+using the simplified case of the Landau damping of Langmuir waves in an
+electrostatic 1D-1V Vlasov-Poisson plasma, showing that the procedure both
+estimates the local rate of energy transfer from the electrostatic field to the
+electrons and indicates the resonant nature of this interaction. Modifications
+of the technique to enable single-point spacecraft measurements of fields and
+particles to diagnose the collisionless damping of turbulent fluctuations in
+the solar wind are discussed, yielding a method with the potential to transform
+our ability to maximize the scientific return from current and upcoming
+spacecraft missions, such as the Magnetospheric Multiscale (MMS) and Solar
+Probe Plus missions.",1607.01738v1
+2016-07-22,Excitation of nonlinear ion acoustic waves in CH plasmas,"Excitation of nonlinear ion acoustic wave (IAW) by an external electric field
+is demonstrated by Vlasov simulation. The frequency calculated by the
+dispersion relation with no damping is verified much closer to the resonance
+frequency of the small-amplitude nonlinear IAW than that calculated by the
+linear dispersion relation. When the wave number $ k\lambda_{De} $ increases,
+the linear Landau damping of the fast mode (its phase velocity is greater than
+any ion's thermal velocity) increases obviously in the region of $ T_i/T_e <
+0.2 $ in which the fast mode is weakly damped mode. As a result, the deviation
+between the frequency calculated by the linear dispersion relation and that by
+the dispersion relation with no damping becomes larger with $k\lambda_{De}$
+increasing. When $k\lambda_{De}$ is not large, such as $k\lambda_{De}=0.1, 0.3,
+0.5$, the nonlinear IAW can be excited by the driver with the linear frequency
+of the modes. However, when $k\lambda_{De}$ is large, such as
+$k\lambda_{De}=0.7$, the linear frequency can not be applied to exciting the
+nonlinear IAW, while the frequency calculated by the dispersion relation with
+no damping can be applied to exciting the nonlinear IAW.",1607.06598v1
+2016-11-17,A stable partitioned FSI algorithm for rigid bodies and incompressible flow. Part II: General formulation,"A stable partitioned algorithm is developed for fluid-structure interaction
+(FSI) problems involving viscous incompressible flow and rigid bodies. This
+{\em added-mass partitioned} (AMP) algorithm remains stable, without
+sub-iterations, for light and even zero mass rigid bodies when added-mass and
+viscous added-damping effects are large. The scheme is based on a generalized
+Robin interface condition for the fluid pressure that includes terms involving
+the linear acceleration and angular acceleration of the rigid body. Added mass
+effects are handled in the Robin condition by inclusion of a boundary integral
+term that depends on the pressure. Added-damping effects due to the viscous
+shear forces on the body are treated by inclusion of added-damping tensors that
+are derived through a linearization of the integrals defining the force and
+torque. Added-damping effects may be important at low Reynolds number, or, for
+example, in the case of a rotating cylinder or rotating sphere when the
+rotational moments of inertia are small. In this second part of a two-part
+series, the general formulation of the AMP scheme is presented including the
+form of the AMP interface conditions and added-damping tensors for general
+geometries. A fully second-order accurate implementation of the AMP scheme is
+developed in two dimensions based on a fractional-step method for the
+incompressible Navier-Stokes equations using finite difference methods and
+overlapping grids to handle the moving geometry. The numerical scheme is
+verified on a number of difficult benchmark problems.",1611.05703v2
+2017-03-01,The Plastic Scintillator Detector at DAMPE,"he DArk Matter Particle Explorer (DAMPE) is a general purposed
+satellite-borne high energy $\gamma-$ray and cosmic ray detector, and among the
+scientific objectives of DAMPE are the searches for the origin of cosmic rays
+and an understanding of Dark Matter particles. As one of the four detectors in
+DAMPE, the Plastic Scintillator Detector (PSD) plays an important role in the
+particle charge measurement and the photons/electrons separation. The PSD has
+82 modules, each consists of a long organic plastic scintillator bar and two
+PMTs at both ends for readout, in two layers and covers an overall active area
+larger than 82 cm $\times$ 82 cm. It can identify the charge states for
+relativistic ions from H to Fe, and the detector efficiency for Z=1 particles
+can reach 0.9999. The PSD has been successfully launched with DAMPE on Dec. 17,
+2015. In this paper, the design, the assembly, the qualification tests of the
+PSD and some of the performance measured on the ground have been described in
+detail.",1703.00098v1
+2017-03-22,Observation of a strong coupling effect on electron-ion collisions in ultracold plasmas,"Ultracold plasmas (UCP) provide a well-controlled system for studying
+multiple aspects in plasma physics that include collisions and strong coupling
+effects. By applying a short electric field pulse to a UCP, a plasma electron
+center-of-mass (CM) oscillation can be initiated. In accessible parameter
+ranges, the damping rate of this oscillation is determined by the electron-ion
+collision rate. We performed measurements of the oscillation damping rate with
+such parameters and compared the measured rates to both a molecular dynamic
+(MD) simulation that includes strong coupling effects and to Monte-Carlo
+collisional operator simulation designed to predict the damping rate including
+only weak coupling considerations. We found agreement between experimentally
+measured damping rate and the MD result. This agreement did require including
+the influence of a previously unreported UCP heating mechanism whereby the
+presence of a DC electric field during ionization increased the electron
+temperature, but estimations and simulations indicate that such a heating
+mechanism should be present for our parameters. The measured damping rate at
+our coldest electron temperature conditions was much faster than the weak
+coupling prediction obtained from the Monte-Carlo operator simulation, which
+indicates the presence of significant strong coupling influence. The density
+averaged electron strong coupling parameter $\Gamma$ measured at our coldest
+electron temperature conditions was 0.35.",1703.07852v2
+2017-04-18,Critical pairing fluctuations in the normal state of a superconductor: pseudogap and quasi-particle damping,"We study the effect of critical pairing fluctuations on the electronic
+properties in the normal state of a clean superconductor in three dimensions.
+Using a functional renormalization group approach to take the non-Gaussian
+nature of critical fluctuations into account, we show microscopically that in
+the BCS regime, where the inverse coherence length is much smaller than the
+Fermi wavevector, critical pairing fluctuations give rise to a non-analytic
+contribution to the quasi-particle damping of order $ T_c \sqrt{Gi} \ln ( 80 /
+Gi )$, where the Ginzburg-Levanyuk number $Gi$ is a dimensionless measure for
+the width of the critical region. As a consequence, there is a temperature
+window above $T_c$ where the quasiparticle damping due to critical pairing
+fluctuations can be larger than the usual $T^2$-Fermi liquid damping due to
+non-critical scattering processes. On the other hand, in the strong coupling
+regime where $Gi$ is of order unity, we find that the quasiparticle damping due
+to critical pairing fluctuations is proportional to the temperature. Moreover,
+we show that in the vicinity of the critical temperature $T_c$ the electronic
+density of states exhibits a fluctuation-induced pseudogap. We also use
+functional renormalization group methods to derive and classify various types
+of processes induced by the pairing interaction in Fermi systems close to the
+superconducting instability.",1704.05282v2
+2017-05-29,Probing decoherence in plasmonic waveguides in the quantum regime,"We experimentally investigate the decoherence of single surface plasmon
+polaritons in metal stripe waveguides. In our study we use a Mach-Zehnder
+configuration previously considered for measuring decoherence in atomic,
+electronic and photonic systems. By placing waveguides of different length in
+one arm we are able to measure the amplitude damping time T_1 = 1.90 +/- 0.01 x
+10^-14 s, pure phase damping time T_2^* = 11.19 +/- 4.89 x 10^-14 s and total
+phase damping time T_2 = 2.83 +/- 0.32 x 10^-14 s. We find that decoherence is
+mainly due to amplitude damping and thus loss arising from inelastic electron
+and photon scattering plays the most important role in the decoherence of
+plasmonic waveguides in the quantum regime. However, pure phase damping is not
+completely negligible. The results will be useful in the design of plasmonic
+waveguide systems for carrying out phase-sensitive quantum applications, such
+as quantum sensing. The probing techniques developed may also be applied to
+other plasmonic nanostructures, such as those used as nanoantennas, as unit
+cells in metamaterials and as nanotraps for cold atoms.",1705.10344v2
+2017-07-21,Spatially Localized Particle Energization by Landau Damping in Current Sheets Produced by Strong Alfven Wave Collisions,"Understanding the removal of energy from turbulent fluctuations in a
+magnetized plasma and the consequent energization of the constituent plasma
+particles is a major goal of heliophysics and astrophysics. Previous work has
+shown that nonlinear interactions among counterpropagating Alfven waves---or
+Alfven wave collisions---are the fundamental building block of astrophysical
+plasma turbulence and naturally generate current sheets in the strongly
+nonlinear limit. A nonlinear gyrokinetic simulation of a strong Alfven wave
+collision is used to examine the damping of the electromagnetic fluctuations
+and the associated energization of particles that occurs in self-consistently
+generated current sheets. A simple model explains the flow of energy due to the
+collisionless damping and the associated particle energization, as well as the
+subsequent thermalization of the particle energy by collisions. The net
+particle energization by the parallel electric field is shown to be spatially
+intermittent, and the nonlinear evolution is essential in enabling that spatial
+non-uniformity. Using the recently developed field-particle correlation
+technique, we show that particles resonant with the Alfven waves in the
+simulation dominate the energy transfer, demonstrating conclusively that Landau
+damping plays a key role in the spatially intermittent damping of the
+electromagnetic fluctuations and consequent energization of the particles in
+this strongly nonlinear simulation.",1708.00757v1
+2017-10-30,Enhancement of intrinsic magnetic damping in defect-free epitaxial Fe3O4 thin films,"We have investigated the magnetic damping of precessional spin dynamics in
+defect-controlled epitaxial grown Fe$_3$O$_4$(111)/Yttria-stabilized Zirconia
+(YSZ) nanoscale films by all-optical pump-probe measurements. The intrinsic
+damping constant of the defect-free Fe$_3$O$_4$ film is found to be strikingly
+larger than that of the as-grown Fe$_3$O$_4$ film with structural defects. We
+demonstrate that the population of the first-order perpendicular standing spin
+wave (PSSW) mode, which is exclusively observed in the defect-free film under
+sufficiently high external magnetic fields, leads to the enhancement of the
+magnetic damping of the uniform precession (Kittel) mode. We propose a physical
+picture in which the PSSW mode acts as an additional channel for the extra
+energy dissipation of the Kittel mode. The energy transfer from Kittel mode to
+PSSW mode increases as in-plane magnetization precession becomes more uniform,
+resulting in the unique intrinsic magnetic damping enhancement in the
+defect-free Fe$_3$O$_4$ film.",1710.10938v2
+2018-05-26,Critical collapse of ultra-relativistic fluids: damping or growth of aspherical deformations,"We perform fully nonlinear numerical simulations to study aspherical
+deformations of the critical self-similar solution in the gravitational
+collapse of ultra-relativistic fluids. Adopting a perturbative calculation,
+Gundlach predicted that these perturbations behave like damped or growing
+oscillations, with the frequency and damping (or growth) rates depending on the
+equation of state. We consider a number of different equations of state and
+degrees of asphericity and find very good agreement with the findings of
+Gundlach for polar $\ell = 2$ modes. For sufficiently soft equations of state,
+the modes are damped, meaning that, in the limit of perfect fine-tuning, the
+spherically symmetric critical solution is recovered. We find that the degree
+of asphericity has at most a small effect on the frequency and damping
+parameter, or on the critical exponents in the power-law scalings. Our findings
+also confirm, for the first time, Gundlach's prediction that the $\ell = 2$
+modes become unstable for sufficiently stiff equations of state. In this regime
+the spherically symmetric self-similar solution can no longer be recovered by
+fine-tuning to the black-hole threshold, and one can no longer expect power-law
+scaling to hold to arbitrarily small scales.",1805.10442v1
+2018-06-19,Non-linear Relaxation of Interacting Bosons Coherently Driven on a Narrow Optical Transition,"We study the dynamics of a two-component Bose-Einstein condensate (BEC) of
+$^{174}$Yb atoms coherently driven on a narrow optical transition. The
+excitation transfers the BEC to a superposition of states with different
+internal and momentum quantum numbers. We observe a crossover with decreasing
+driving strength between a regime of damped oscillations, where coherent
+driving prevails, and an incoherent regime, where relaxation takes over.
+Several relaxation mechanisms are involved: inelastic losses involving two
+excited atoms, leading to a non-exponential decay of populations; Doppler
+broadening due to the finite momentum width of the BEC and inhomogeneous
+elastic interactions, both leading to dephasing and to damping of the
+oscillations. We compare our observations to a two-component Gross-Pitaevskii
+(GP) model that fully includes these effects. For small or moderate densities,
+the damping of the oscillations is mostly due to Doppler broadening. In this
+regime, we find excellent agreement between the model and the experimental
+results. For higher densities, the role of interactions increases and so does
+the damping rate of the oscillations. The damping in the GP model is less
+pronounced than in the experiment, possibly a hint for many-body effects not
+captured by the mean-field description.",1806.07210v2
+2018-10-16,The Solution to the Differential Equation with Linear Damping describing a Physical Systems governed by a Cubic Energy Potential,"An analytical solution to the nonlinear differential equation describing the
+equation of motion of a particle moving in an unforced physical system with
+linear damping, governed by a cubic potential well, is presented in terms of
+the Jacobi elliptic functions. In the attractive region of the potential the
+system becomes an anharmonic damped oscillator, however with asymmetric
+displacement. An expression for the period of oscillation is derived, which for
+a nonlinear damped system is time dependent, and in particular it contains a
+quartic root of an exponentially decaying term in the denominator. Initially
+the period is longer as compared to that of a linear oscillator, however
+gradually it decreases to that of a linear damped oscillator.
+  Transforming the undamped nonlinear differential equation into the
+differential equation describing orbital motion of planets, the perihelion
+advance of Mercury can be estimated to 42.98 arcseconds/century, close to
+present day observations of 43.1 arcseconds/century.
+  Some familiarity with the Jacobi elliptic functions is required, in
+particular with respect to the differential behavior of these functions,
+however, they are standard functions of advanced mathematical computer algebra
+tools. The expression derived for the solution to the nonlinear physical
+system, and in particular the expression for the period of oscillation, is
+useful for an accurate evaluation of experiments in introductory and advanced
+physics labs, but also of interest for specialists working with nonlinear
+phenomena governed by the cubic potential well.",1810.10336v1
+2019-01-10,Damping and softening of transverse acoustic phonons in colossal magnetoresistive La$_{0.7}$Ca$_{0.3}$MnO$_3$ and La$_{0.7}$Sr$_{0.3}$MnO$_3$,"Neutron spectroscopy is used to probe transverse acoustic phonons near the
+(2, 2, 0) Bragg position in colossal magnetoresistive La0.7Ca0.3MnO3 and
+La0.7Sr0.3MnO3. Upon warming to temperatures near Tc = 257 K the phonon peaks
+in La0.7Ca0.3MnO3 soften and damp significantly with the phonon half width at
+half maximum approaching 2.5 meV for phonons at a reduced wave vector of q =
+(0.2, 0.2, 0). Concurrently a quasielastic component develops that dominates
+the spectrum near the polaron position at high temperatures. This quasielastic
+scattering is ~5 times more intense near Tc than in La0.7Sr0.3MnO3 despite
+comparable structural distortions in the two. The damping becomes more
+significant near the polaron position with a temperature dependence similar to
+that of polaron structural distortions. An applied magnetic field of 9.5 T only
+partially reverses the damping and quasielastic component, despite smaller
+fields being sufficient to drive the colossal magnetoresistive effect. The
+phonon energy, on the other hand, is unaffected by field. The damping in
+La0.7Sr0.3MnO3 near Tc at a reduced wave vector of q = (0.25, 0.25, 0) is
+significantly smaller but displays a similar trend with an applied magnetic
+field.",1901.03394v1
+2019-03-13,Inference of magnetic field strength and density from damped transverse coronal waves,"A classic application of coronal seismology uses transverse oscillations of
+waveguides to obtain estimates of the magnetic field strength. The procedure
+requires information on the density of the structures. Often, it ignores the
+damping of the oscillations. We computed marginal posteriors for parameters
+such as the waveguide density; the density contrast; the transverse
+inhomogeneity length-scale; and the magnetic field strength, under the
+assumption that the oscillations can be modelled as standing
+magnetohydrodynamic (MHD) kink modes damped by resonant absorption. Our results
+show that the magnetic field strength can be properly inferred, even if the
+densities inside and outside the structure are largely unknown. Incorporating
+observational estimates of plasma density further constrains the obtained
+posteriors. The amount of information one is willing to include (a priori) for
+the density and the density contrast influences their corresponding posteriors,
+but very little the inferred magnetic field strength. The decision to include
+or leave out the information on the damping and the damping time-scales have a
+minimal impact on the obtained magnetic field strength. In contrast to the
+classic method which provides with numerical estimates with error bars or
+possible ranges of variation for the magnetic field strength, Bayesian methods
+offer the full distribution of plausibility over the considered range of
+possible values. The methods are applied to available datasets of observed
+transverse loop oscillations, can be extended to prominence fine structures or
+chromospheric spicules and implemented to propagating waves in addition to
+standing oscillations.",1903.05437v1
+2019-03-14,A metal-poor damped Ly-alpha system at redshift 6.4,"We identify a strong Ly-alpha damping wing profile in the spectrum of the
+quasar P183+05 at z=6.4386. Given the detection of several narrow metal
+absorption lines at z=6.40392, the most likely explanation for the absorption
+profile is that it is due to a damped Ly-alpha system. However, in order to
+match the data a contribution of an intergalactic medium 5-38% neutral or
+additional weaker absorbers near the quasar is also required. The absorption
+system presented here is the most distant damped Ly-alpha system currently
+known. We estimate an HI column density ($10^{20.68\pm0.25}\,$cm$^{-2}$),
+metallicity ([O/H]$=-2.92\pm 0.32$), and relative chemical abundances of a
+system consistent with a low-mass galaxy during the first Gyr of the universe.
+This object is among the most metal-poor damped Ly-alpha systems known and,
+even though it is observed only ~850 Myr after the big bang, its relative
+abundances do not show signatures of chemical enrichment by Population III
+stars.",1903.06186v2
+2019-04-30,DmpIRFs and DmpST: DAMPE Instrument Response Functions and Science Tools for Gamma-Ray Data Analysis,"GeV gamma ray is an important observation target of DArk Matter Particle
+Explorer (DAMPE) for indirect dark matter searching and high energy
+astrophysics. We present in this work a set of accurate instrument response
+functions of DAMPE (DmpIRFs) including the effective area, point-spread
+function and energy dispersion that are crucial for the gamma-ray data analysis
+based on the high statistics simulation data. A dedicated software named DmpST
+is developed to facilitate the scientific analyses of DAMPE gamma-ray data.
+Considering the limited number of photons and the angular resolution of DAMPE,
+the maximum likelihood method is adopted in the DmpST to better disentangle
+different source components. The basic mathematics and the framework regarding
+this software are also introduced in this paper.",1904.13098v1
+2019-05-14,Fractional damping through restricted calculus of variations,"We deliver a novel approach towards the variational description of Lagrangian
+mechanical systems subject to fractional damping by establishing a restricted
+Hamilton's principle. Fractional damping is a particular instance of non-local
+(in time) damping, which is ubiquitous in mechanical engineering applications.
+The restricted Hamilton's principle relies on including fractional derivatives
+to the state space, the doubling of curves (which implies an extra mirror
+system) and the restriction of the class of varied curves. We will obtain the
+correct dynamics, and will show rigorously that the extra mirror dynamics is
+nothing but the main one in reversed time; thus, the restricted Hamilton's
+principle is not adding extra physics to the original system. The price to pay,
+on the other hand, is that the fractional damped dynamics is only a sufficient
+condition for the extremals of the action. In addition, we proceed to
+discretise the new principle. This discretisation provides a set of numerical
+integrators for the continuous dynamics that we denote Fractional Variational
+Integrators (FVIs). The discrete dynamics is obtained upon the same
+ingredients, say doubling of discrete curves and restriction of the discrete
+variations. We display the performance of the FVIs, which have local truncation
+order 1, in two examples. As other integrators with variational origin, for
+instance those generated by the discrete Lagrange-d'Alembert principle, they
+show a superior performance tracking the dissipative energy, in opposition to
+direct (order 1) discretisations of the dissipative equations, such as explicit
+and implicit Euler schemes.",1905.05608v1
+2019-07-16,Damping of slow magnetoacoustic oscillations by the misbalance between heating and cooling processes in the solar corona,"Rapidly decaying slow magnetoacoustic waves are regularly observed in the
+solar coronal structures, offering a promising tool for a seismological
+diagnostics of the coronal plasma, including its thermodynamical properties.
+The effect of damping of standing slow magnetoacoustic oscillations in the
+solar coronal loops is investigated accounting for the field-aligned thermal
+conductivity and a wave-induced misbalance between radiative cooling and some
+unspecified heating rates. The non-adiabatic terms were allowed to be
+arbitrarily large, corresponding to the observed values. The thermal
+conductivity was taken in its classical form, and a power-law dependence of the
+heating function on the density and temperature was assumed. The analysis was
+conducted in the linear regime and in the infinite magnetic field
+approximation. The wave dynamics is found to be highly sensitive to the
+characteristic time scales of the thermal misbalance. Depending on certain
+values of the misbalance time scales three regimes of the wave evolution were
+identified, namely the regime of a suppressed damping, enhanced damping where
+the damping rate drops down to the observational values, and acoustic
+over-stability. The specific regime is determined by the dependences of the
+radiative cooling and heating functions on thermodynamical parameters of the
+plasma in the vicinity of the perturbed thermal equilibrium. The comparison of
+the observed and theoretically derived decay times and oscillation periods
+allows us to constrain the coronal heating function. For typical coronal
+parameters, the observed properties of standing slow magnetoacoustic
+oscillations could be readily reproduced with a reasonable choice of the
+heating function.",1907.07051v1
+2019-08-22,Influence of structure and cation distribution on magnetic anisotropy and damping in Zn/Al doped nickel ferrites,"An in-depth analysis of Zn/Al doped nickel ferrites grown by reactive
+magnetron sputtering is relevant due to their promising characteristics for
+applications in spintronics. The material is insulating and ferromagnetic at
+room temperature with an additional low magnetic damping. By studying the
+complex interplay between strain and cation distribution their impact on the
+magnetic properties, i.e. anisotropy, damping and g-factor is unravelled. In
+particular, a strong influence of the lattice site occupation of
+Ni$^{2+}_{\text{Td}}$ and cation coordination of Fe$^{2+}_{\text{Oh}}$ on the
+intrinsic damping is found. Furthermore, the critical role of the incorporation
+of Zn$^{2+}$ and Al$^{3+}$ is evidenced by comparison with a sample of altered
+composition. Especially, the dopant Zn$^{2+}$ is evidenced as a tuning factor
+for Ni$^{2+}_{\text{Td}}$ and therefore unquenched orbital moments directly
+controlling the g-factor. A strain-independent reduction of the magnetic
+anisotropy and damping by adapting the cation distribution is demonstrated.",1908.08257v3
+2019-09-11,Critical corrections to formulations of nonlinear energy dissipation of ultrasonically excited bubbles and a unifying parameter to asses and enhance bubble activity in applications,"Nonlinear oscillations of bubbles can significantly increase the attenuation
+of the host media. Optimization of bubble related applications needs a
+realistic estimation of the medium attenuation and bubble activity. A correct
+estimation of the wave attenuation in bubbly media requires an accurate
+estimation of the power dissipated by nonlinear oscillations of bubbles.
+Pioneering work of Louisnard \cite{1} meticulously derived the nonlinear energy
+terms for viscous and thermal damping; however, radiation damping arising from
+the compressibility of the liquid was neglected. Jamshidi $\&$ Brenner \cite{2}
+have considered the effects of the compressibility of the liquid and showed
+that damping due to radiation becomes the most significant factor at pressures
+above the blake threshold. Despite the improvement in their formulation;
+however, the radiation damping term estimates non-physical values for some
+frequency and pressure regions including near resonance oscillations. Thus, the
+new terms arising from the compressibility of the liquid needs critical
+assessment. In this work, we provide critical corrections to the present
+formulations. Importance of the new corrections are highlighted by the
+scattering to damping ratio (STDR). We then introduce a unifying parameter to
+assess the efficacy of applications; this parameter is defined as the
+multiplication of maximum scattered pressure by STDR.",1909.04864v1
+2019-09-14,Measurement-Based Wide-Area Damping of Inter-Area Oscillations based on MIMO Identification,"Interconnected power grid exhibits oscillatory response after a disturbance
+in the system. One such type of oscillations, the inter-area oscillations has
+the oscillation frequency in the range of 0.1 to 1 Hz. The damping of
+inter-area oscillations is difficult with local controllers, but it can be
+achieved using a Wide Area Damping Controller (WADC). For effective control,
+the input to the WADC should be the most observable signal and the WADC output
+should be sent to the most controllable generator. This paper presents a
+measurement-based novel algorithm for multi-input-multi-output (MIMO) transfer
+function identification of the power system based on optimization to estimate
+such oscillation frequencies. Based on the MIMO transfer function the optimal
+control loop for WADC is estimated. The WADC design is based on the discrete
+linear quadratic regulator (DLQR) and Kalman filtering for damping of
+inter-area oscillations. Since the MIMO identification is based on actual
+measurements, the proposed method can accurately monitor changes in the power
+grid whereas the conventional methods are based on small-signal analysis of a
+linearized model which does not consider changing operating conditions. The
+overall algorithm is implemented and validated on a RTDS/RSCAD and MATLAB
+real-time co-simulation platform using two-area and IEEE 39 bus power system
+models.",1909.06687v1
+2020-03-16,Spin-orbit torques originating from bulk and interface in Pt-based structures,"We investigated spin-orbit torques in prototypical Pt-based spintronic
+devices. We found that, in Pt/Ni and Pt/Fe bilayers, the damping-like torque
+efficiency depends on the thickness of the Pt layer. We also found that the
+damping-like torque efficiency is almost identical in the Pt/Ni and Pt/Fe
+bilayers despite the stronger spin memory loss at the Pt/Fe interface. These
+results suggest that although the dominant source of the damping-like torque is
+the bulk spin Hall effect in the Pt layer, a sizable damping-like torque is
+generated by the interface in the Pt/Fe bilayer due to the stronger interfacial
+spin-orbit coupling. In contrast to the damping-like torque, whose magnitude
+and sign are almost identical in the Pt/Ni and Pt/Fe bilayers, the field-like
+torque strongly depends on the choice of the ferromagnetic layer. The sign of
+the field-like torque originating from the bulk spin Hall effect in the Pt
+layer is opposite between the Pt/Ni and Pt/Fe bilayers, which can be attributed
+to the opposite sign of the imaginary part of the spin-mixing conductance.
+These results demonstrate that the spin-orbit torques are quite sensitive to
+the electronic structure of the FM layer.",2003.07271v2
+2020-03-23,Heat-like and wave-like lifespan estimates for solutions of semilinear damped wave equations via a Kato's type lemma,"In this paper we study several semilinear damped wave equations with
+""subcritical"" nonlinearities, focusing on demonstrating lifespan estimates for
+energy solutions. Our main concern is on equations with scale-invariant damping
+and mass. Under different assumptions imposed on the initial data, lifespan
+estimates from above are clearly showed. The key fact is that we find
+""transition surfaces"", which distinguish lifespan estimates between ""wave-like""
+and ""heat-like"" behaviours. Moreover we conjecture that the lifespan estimates
+on the ""transition surfaces"" can be logarithmically improved. As direct
+consequences, we reorganize the blow-up results and lifespan estimates for the
+massless case in which the ""transition surfaces"" degenerate to ""transition
+curves"". Furthermore, we obtain improved lifespan estimates in one space
+dimension, comparing to the known results. We also study semilinear wave
+equations with the scattering damping and negative mass term, and find that if
+the decay rate of the mass term equals to 2, the lifespan estimate is the same
+as one special case of the equations with the scale-invariant damping and
+positive mass. The main strategy of the proof consists of a Kato's type lemma
+in integral form, which is established by iteration argument.",2003.10578v1
+2020-09-03,Dynamics of magnetic collective modes in the square and triangular lattice Mott insulators at finite temperature,"We study the equilibrium dynamics of magnetic moments in the Mott insulating
+phase of the Hubbard model on the square and triangular lattice. We rewrite the
+Hubbard interaction in terms of an auxiliary vector field and use a recently
+developed Langevin scheme to study its dynamics. A thermal `noise', derivable
+approximately from the Keldysh formalism, allows us to study the effect of
+finite temperature. At strong coupling, $U \gg t$, where $U$ is the local
+repulsion and $t$ the nearest neighbour hopping, our results reproduce the well
+known dynamics of the nearest neighbour Heisenberg model with exchange $J \sim
+{\cal O}(t^2/U)$. These include crossover from weakly damped dispersive modes
+at temperature $T \ll J$ to strong damping at $T \sim {\cal O}(J)$, and
+diffusive dynamics at $T \gg J$. The crossover temperatures are naturally
+proportional to $J$. To highlight the progressive deviation from Heisenberg
+physics as $U/t$ reduces we compute an effective exchange scale $J_{eff}(U)$
+from the low temperature spin wave velocity. We discover two features in the
+dynamical behaviour with decreasing $U/t$: (i)~the low temperature dispersion
+deviates from the Heisenberg result, as expected, due to longer range and
+multispin interactions, and (ii)~the crossovers between weak damping, strong
+damping, and diffusion take place at noticeably lower values of $T/J_{eff}$. We
+relate this to enhanced mode coupling, in particular to thermal amplitude
+fluctuations, at weaker $U/t$. A comparison of the square and triangular
+lattice reveals the additional effect of geometric frustration on damping.",2009.01833v2
+2020-09-15,Classification of the mechanisms of wave energy dissipation in the nonlinear oscillations of coated and uncoated bubbles,"Acoustic waves are dissipated when they pass through bubbly media.
+Dissipation by bubbles takes place through thermal damping (Td), radiation
+damping (Rd) and damping due to the friction of the liquid (Ld) and friction of
+the coating (Cd). Knowledge of the contributions of the Td, Rd, Ld and Cd
+during nonlinear bubble oscillations will help in optimizing bubble and
+ultrasound exposure parameters for the relevant applications by maximizing a
+desirable parameter. In this work we investigate the mechanisms of dissipation
+in bubble oscillations and their contribution to the total damping (Wtotal) in
+various nonlinear regimes. By using bifurcation analysis, we have classified
+nonlinear dynamics of bubbles that are sonicated with their 3rd superharmonic
+(SuH) and 2nd SuH resonance frequency (fr), pressure dependent resonance
+frequency (PDfr), fr, subharmonic (SH) resonance (fsh=2fr), pressure dependent
+SH resonance (PDfsh) and 1/3 order SH resonance. The corresponding Td, Rd, Ld,
+Cd, Wtotal, scattering to dissipation ratio (STDR), maximum wall velocity and
+maximum back-scattered pressure from non-destructive oscillations of bubbles
+were calculated and analyzed using the bifurcation diagrams. We classified
+different regimes of dissipation and provided parameter regions in which a
+particular parameter of interest (e.g. Rd) can be enhanced. Afterwards enhanced
+bubble activity is linked to some relevant applications in ultrasound. This
+paper represents the first comprehensive analysis of the nonlinear oscillations
+regimes and the corresponding damping mechanisms.",2009.07380v1
+2020-11-18,The effect of redshift degeneracy and the damping effect of viscous medium on the information extracted from gravitational wave signals,"Considering the cosmological redshift $z_c$ , the mass of GW source extracted
+from GW signal is $1+z_c$ times larger than its intrinsic value, and distance
+between detector and GW source should be regarded as luminosity distance.
+However, besides cosmological redshift, there are other kinds of redshifts
+should be considered, which is actually ignored, in the analysis of GW data,
+such as Doppler redshift and gravitational redshift, so the parameters
+extracted from GW may deviate from their intrinsic values. Another factor that
+may affect GW is the viscous medium in propagation path of GW, which may damp
+the GW with a damping rate of $16{\pi}G{\eta}$. Some studies indicate dark
+matter may interact with each other, thus dark matter may be the origin of
+viscosity of cosmic medium. Then the GW may be rapidly damped by the viscous
+medium that is made of dark matter, such as dark matter ""mini-spike"" around
+intermediate mass black hole. In this article, we mainly discuss how Doppler
+and gravitational redshift, together with the damping effect of viscous medium,
+affect the information, such as the mass and redshift of GW source, extracted
+from GW signals.",2011.09169v2
+2020-12-28,On the Efficacy of Friction Damping in the Presence of Nonlinear Modal Interactions,"This work addresses friction-induced modal interactions in jointed
+structures, and their effects on the passive mitigation of vibrations by means
+of friction damping. Under the condition of (nearly) commensurable natural
+frequencies, the nonlinear character of friction can cause so-called nonlinear
+modal interactions. If harmonic forcing near the natural frequency of a
+specific mode is applied, for instance, another mode may be excited due to
+nonlinear energy transfer and thus contribute considerably to the vibration
+response. We investigate how this phenomenon affects the performance of
+friction damping. To this end, we study the steady-state, periodic forced
+vibrations of a system of two beams connected via a local mechanical friction
+joint. The system can be tuned to continuously adjust the ratio between the
+first two natural frequencies in the range around the $1:3$ internal resonance,
+in order to trigger or suppress the emergence of modal interactions. Due to the
+re-distribution of the vibration energy, the vibration level can in fact be
+reduced in certain situations. However, in other situations, the multi-harmonic
+character of the vibration has detrimental effects on the effective damping
+provided by the friction joint. The resulting response level can be
+significantly larger than in the absence of modal interactions. Moreover, it is
+shown that the vibration behavior is highly sensitive in the neighborhood of
+internal resonances. It is thus concluded that the condition of internal
+resonance should be avoided in the design of friction-damped systems.",2101.03232v1
+2021-06-30,Origin of Nonlinear Damping due to Mode Coupling in Auto-Oscillatory Modes Strongly Driven by Spin-Orbit Torque,"We investigate the physical origin of nonlinear damping due to mode coupling
+between several auto-oscillatory modes driven by spin-orbit torque in
+constricted Py/Pt heterostructures by examining the dependence of
+auto-oscillation on temperature and applied field orientation. We observe a
+transition in the nonlinear damping of the auto-oscillation modes extracted
+from the total oscillation power as a function of drive current, which
+coincides with the onset of power redistribution amongst several modes and the
+crossover from linewidth narrowing to linewidth broadening in all individual
+modes. This indicates the activation of another relaxation process by nonlinear
+magnon-magnon scattering within the modes. We also find that both nonlinear
+damping and threshold current in the mode-interaction damping regime at high
+drive current after transition are temperature independent, suggesting that the
+mode coupling occurs dominantly through a non-thermal magnon scattering process
+via a dipole or exchange interaction rather than thermally excited
+magnon-mediated scattering. This finding presents a promising pathway to
+overcome the current limitations of efficiently controlling the interaction
+between two highly nonlinear magnetic oscillators to prevent mode crosstalk or
+inter-mode energy transfer and deepens understanding of complex nonlinear spin
+dynamics in multimode spin wave systems.",2107.00150v2
+2021-07-15,On the long-time behavior for a damped Navier-Stokes-Bardina model,"In this paper, we consider a damped Navier-Stokes-Bardina model posed on the
+whole three-dimensional. These equations have an important physical motivation
+and they arise from some oceanic model. From the mathematical point of view,
+they write down as the well-know Navier-Stokes equations with an additional
+nonlocal operator in their nonlinear transport term, and moreover, with an
+additional damping term depending of a parameter $\beta>0$. We study first the
+existence and uniqueness of global in time weak solutions in the energy space.
+Thereafter, our main objective is to describe the long time behavior of these
+solutions. For this, we use some tools in the theory of dynamical systems to
+prove the existence of a global attractor, which is a compact subset in the
+energy space attracting all the weak solutions when the time goes to infinity.
+Moreover, we derive an upper bound for the fractal dimension of the global
+attractor associated to these equations.
+  Finally, we find a range of values for the damping parameter $\beta>0$, where
+we are able to give an acutely description of the internal structure of the
+global attractor. More precisely, we prove that the global attractor only
+contains the stationary (time-independing) solution of the damped
+Navier-Stokes-Bardina equations.",2107.07070v2
+2021-07-17,Plasmon-Exciton Coupling Effect on Plasmon Damping,"Plasmon decay via the surface or interface is a critical process for
+practical energy conversion and plasmonic catalysis. However, the relationship
+between plasmon damping and the coupling between the plasmon and 2D materials
+is still unclear. The spectral splitting due to plasmon-exciton interaction
+impedes the conventional single-particle method to evaluate the plasmon damping
+rate by the spectral linewidth directly. Here, we investigated the interaction
+between a single gold nanorod (GNR) and 2D materials using the single-particle
+spectroscopy method assisted with in situ nanomanipulation technique by
+comparing scattering intensity and linewidth together. Our approach allows us
+to indisputably identify that the plasmon-exciton coupling in the GNR-WSe2
+hybrid would induce plasmon damping. We can also isolate the contribution
+between the charge transfer channel and resonant energy transfer channel for
+the plasmon decay in the GNR-graphene hybrid by comparing that with thin hBN
+layers as an intermediate medium to block the charge transfer. We find out that
+the contact layer between the GNR and 2D materials contributes most of the
+interfacial plasmon damping. These findings contribute to a deep understanding
+of interfacial excitonic effects on the plasmon and 2D materials hybrid.",2107.08230v1
+2021-10-12,Outflows in the presence of cosmic rays and waves with cooling,"Plasma outflow from a gravitational potential well with cosmic rays and
+self-excited Alfv\'en waves with cooling and wave damping is studied in the
+hydrodynamics regime. We study outflows in the presence of cosmic ray and
+Alfv\'en waves including the effect of cooling and wave damping. We seek
+physically allowable steady-state subsonic-supersonic transonic solutions. We
+adopted a multi-fluid hydrodynamical model for the cosmic ray plasma system.
+Thermal plasma, cosmic rays, and self-excited Alfv\'en waves are treated as
+fluids. Interactions such as cosmic-ray streaming instability, cooling, and
+wave damping were fully taken into account. We considered one-dimensional
+geometry and explored steady-state solutions. The model is reduced to a set of
+ordinary differential equations, which we solved for subsonic-supersonic
+transonic solutions with given boundary conditions at the base of the
+gravitational potential well. We find that physically allowable
+subsonic-supersonic transonic solutions exist for a wide range of parameters.
+We studied the three-fluid system (considering only forward-propagating
+Alfv\'en waves) in detail. We examined the cases with and without cosmic ray
+diffusion separately. Comparisons of solutions with and without cooling and
+with and without wave damping for the same set of boundary conditions (on
+density, pressures of thermal gas, cosmic rays and waves) are presented. We
+also present the interesting case of a four-fluid system (both forward- and
+backward-propagating Alfv\'en waves are included), highlighting the intriguing
+relation between different components.",2110.06170v1
+2021-11-19,Finite time extinction for a class of damped Schr{ö}dinger equations with a singular saturated nonlinearity,"We present some sharper finite extinction time results for solutions of a
+class of damped nonlinear Schr{\""o}dinger equations when the nonlinear damping
+term corresponds to the limit cases of some ``saturating non-Kerr law''
+$F(|u|^2)u=\frac{a}{\varepsilon+(|u|^2)^\alpha}u,$ with $a\in\mathbb{C},$
+$\varepsilon\geqslant0,$ $2\alpha=(1-m)$ and $m\in[0,1).$ To carry out the
+improvement of previous results in the literature we present in this paper a
+careful revision of the existence and regularity of weak solutions under very
+general assumptions on the data. We prove that the problem can be solved in the
+very general framework of the maximal monotone operators theory, even under a
+lack of regularity of the damping term. This allows us to consider, among other
+things, the singular case $m=0.$ We replace the above approximation of the
+damping term by a different one which keeps the monotonicity for any
+$\varepsilon\geqslant0$. We prove that, when $m=0,$ the finite extinction time
+of the solution arises for merely bounded right hand side data $f(t,x).$ This
+is specially useful in the applications in which the Schr{\""o}dinger equation
+is coupled with some other functions satisfying some additional equations.",2111.10136v2
+2022-01-26,Effect of Chiral Damping on the dynamics of chiral domain walls and skyrmions,"Friction plays an essential role in most physical processes that we
+experience in our everyday life. Examples range from our ability to walk or
+swim, to setting boundaries of speed and fuel efficiency of moving vehicles. In
+magnetic systems, the displacement of chiral domain walls (DW) and skyrmions
+(SK) by Spin Orbit Torques (SOT), is also prone to friction. Chiral damping,
+the dissipative counterpart of the Dzyaloshinskii Moriya Interaction (DMI),
+plays a central role in these dynamics. Despite experimental observation, and
+numerous theoretical studies confirming its existence, the influence of chiral
+damping on DW and SK dynamics has remained elusive due to the difficulty of
+discriminating from DMI. Here we unveil the effect that chiral damping has on
+the flow motion of DWs and SKs driven by current and magnetic field. We use a
+static in-plane field to lift the chiral degeneracy. As the in-plane field is
+increased, the chiral asymmetry changes sign. When considered separately,
+neither DMI nor chiral damping can explain the sign reversal of the asymmetry,
+which we prove to be the result of their competing effects. Finally, numerical
+modelling unveils the non-linear nature of chiral dissipation and its critical
+role for the stabilization of moving SKs.",2201.10742v1
+2022-01-27,A Study on Monte Carlo simulation of the radiation environment above GeV at the DAMPE orbit,"The Dark Matter Particle Explorer (DAMPE) has been undergoing a stable
+on-orbit operation for more than 6 years and acquired observation of over 11
+billion events. And a better understanding of the overall radiation environment
+on the DAMPE orbit is crucial for both simulation data production and flight
+data analysis. In this work, we study the radiation environment at the low
+Earth orbit and develop a simulation software package using the framework of
+ATMNC3, in which state-of-the-art full 3D models of the Earth's atmospheric and
+magnetic-field configurations is integrated. We consider in our Monte Carlo
+procedure event-by-event propagation of the cosmic rays in the geomagnetic
+field and their interaction with the Earth's atmosphere, focusing on the
+particles above GeV that are able to trigger the DAMPE data acquisition system.
+We compare the simulation results with the cosmic-ray electrons and positrons
+(CREs) flux measurements made by DAMPE. The overall agreement on both the
+spectral and angular distribution of the CREs flux demonstrates that our
+simulation is well established. Our software package could be of more general
+usage for the simulation of the radiation environment at the low Earth orbit of
+various altitudes.",2201.11364v1
+2022-06-08,Motion control with optimal nonlinear damping: from theory to experiment,"Optimal nonlinear damping control was recently introduced for the
+second-order SISO systems, showing some advantages over a classical PD feedback
+controller. This paper summarizes the main theoretical developments and
+properties of the optimal nonlinear damping controller and demonstrates, for
+the first time, its practical experimental evaluation. An extended analysis and
+application to more realistic (than solely the double-integrator) motion
+systems are also given in the theoretical part of the paper. As comparative
+linear feedback controller, a PD one is taken, with the single tunable gain and
+direct compensation of the plant time constant. The second, namely
+experimental, part of the paper includes the voice-coil drive system with
+relatively high level of the process and measurement noise, for which the
+standard linear model is first identified in frequency domain. The linear
+approximation by two-parameters model forms the basis for designing the PD
+reference controller, which fixed feedback gain is the same as for the optimal
+nonlinear damping control. A robust sliding-mode based differentiator is used
+in both controllers for a reliable velocity estimation required for the
+feedback. The reference PD and the proposed optimal nonlinear damping
+controller, both with the same single design parameter, are compared
+experimentally with respect to trajectory tracking and disturbance rejection.",2206.03802v2
+2022-09-22,Neutrino Fast Flavor Pendulum. Part 2: Collisional Damping,"In compact astrophysical objects, the neutrino density can be so high that
+neutrino-neutrino refraction can lead to fast flavor conversion of the kind
+$\nu_e \bar\nu_e \leftrightarrow \nu_x \bar\nu_x$ with $x=\mu,\tau$, depending
+on the neutrino angle distribution. Previously, we have shown that in a
+homogeneous, axisymmetric two-flavor system, these collective solutions evolve
+in analogy to a gyroscopic pendulum. In flavor space, its deviation from the
+weak-interaction direction is quantified by a variable $\cos\vartheta$ that
+moves between $+1$ and $\cos\vartheta_{\rm min}$, the latter following from a
+linear mode analysis. As a next step, we include collisional damping of flavor
+coherence, assuming a common damping rate $\Gamma$ for all modes. Empirically
+we find that the damped pendular motion reaches an asymptotic level of pair
+conversion $f=A+(1-A)\cos\vartheta_{\rm min}$ (numerically $A\simeq 0.370$)
+that does not depend on details of the angular distribution (except for fixing
+$\cos\vartheta_{\rm min}$), the initial seed, nor $\Gamma$. On the other hand,
+even a small asymmetry between the neutrino and antineutrino damping rates
+strongly changes this picture and can even enable flavor instabilities in
+otherwise stable systems.",2209.11235v3
+2022-10-12,Second order two-species systems with nonlocal interactions: existence and large damping limits,"We study the mathematical theory of second order systems with two species,
+arising in the dynamics of interacting particles subject to linear damping, to
+nonlocal forces and to external ones, and resulting into a nonlocal version of
+the compressible Euler system with linear damping. Our results are limited to
+the $1$ space dimensional case but allow for initial data taken in a
+Wasserstein space of probability measures. We first consider the case of smooth
+nonlocal interaction potentials, not subject to any symmetry condition, and
+prove existence and uniqueness. The concept of solutions relies on a stickiness
+condition in case of collisions, in the spirit of previous works in the
+literature. The result uses concepts from classical Hilbert space theory of
+gradient flows (cf. Brezis [7]) and a trick used in [4]. We then consider a
+large-time and large-damping scaled version of our system and prove convergence
+to solutions to the corresponding first order system. Finally, we consider the
+case of Newtonian potentials -- subject to symmetry of the cross-interaction
+potentials -- and external convex potentials. After showing existence in the
+sticky particles framework in the spirit of [4], we prove convergence for large
+times towards Dirac delta solutions for the two densities. All the results
+share a common technical framework in that solutions are considered in a
+Lagrangian framework, which allows to estimate the behavior of solutions via
+$L^2$ estimates of the pseudo-inverse variables corresponding to the two
+densities. In particular, due to this technique, the large-damping result holds
+under a rather weak condition on the initial data, which does not require
+well-prepared initial velocities. We complement the results with numerical
+simulations.",2210.06162v1
+2022-10-12,Stability of the Néel quantum critical point in the presence of Dirac fermions,"We investigate the stability of the N\'eel quantum critical point of
+two-dimensional quantum antiferromagnets, described by a non-linear $\sigma$
+model (NL$\sigma$M), in the presence of a Kondo coupling to $N_f$ flavours of
+two-component Dirac fermion fields. The long-wavelength order parameter
+fluctuations are subject to Landau damping by electronic particle-hole
+fluctuations. Using momentum-shell RG, we demonstrate that the Landau damping
+is weakly irrelevant at the N\'eel quantum critical point, despite the fact
+that the corresponding self-energy correction dominates over the quadratic
+gradient terms in the IR limit. In the ordered phase, the Landau damping
+increases under the RG, indicative of damped spin-wave excitations. Although
+the Kondo coupling is weakly relevant, sufficiently strong Landau damping
+renders the N\'eel quantum critical point quasi-stable for $N_f\ge 4$ and
+thermodynamically stable for $N_f<4$. In the latter case, we identify a new
+multi-critical point which describes the transition between the N\'eel critical
+and Kondo run-away regimes. The symmetry breaking at this fixed point results
+in the opening of a gap in the Dirac fermion spectrum. Approaching the
+multi-critical point from the disordered phase, the fermionic quasiparticle
+residue vanishes, giving rise to non-Fermi-liquid behavior.",2210.06577v3
+2022-11-13,Damping analysis of Floating Offshore Wind Turbine (FOWT): a new control strategy reducing the platform vibrations,"In this paper, the coupled dynamics of the floating platform and the WTG
+rotor is analysed. In particular, the damping is explicitly derived from the
+coupled equations of rotor and floating platform. The analysis of the damping
+leads to the study of the instability phenomena and it derives the explicit
+conditions that lead to the Non Minimum Phase Zero (NMPZ). Two NMPZs, one
+related to the rotor dynamics and the other one to the platform pitch dynamics,
+are analysed. The latter is a novelty and it is analysed in this work,
+providing the community of an explicit condition for its verification. The
+domain of the instability of the platform is explicitly derived from the
+coupled system of equations. In the second part of the paper, from the analysis
+of the damping of the floating platform, a new strategy for the control of
+FOWTs is proposed. This strategy allows one to impose to the controller an
+explicit level of damping in the platform pitch motion without changing the
+period of platform pitching. Finally the new strategy is compared to the one
+without compensation by performing aero-hydro-servo-elastic numerical
+simulations of the UMaine IEA15MW FOWT. Generated power, movements, blade pitch
+and tower base fatigue are compared showing that the new control strategy can
+reduce fatigue in the structure without affecting the power production.",2211.10362v1
+2022-11-22,Universal Dynamics of Damped-Driven Systems: The Logistic Map as a Normal Form for Energy Balance,"Damped-driven systems are ubiquitous in engineering and science. Despite the
+diversity of physical processes observed in a broad range of applications, the
+underlying instabilities observed in practice have a universal characterization
+which is determined by the overall gain and loss curves of a given system. The
+universal behavior of damped-driven systems can be understood from a
+geometrical description of the energy balance with a minimal number of
+assumptions. The assumptions on the energy dynamics are as follows: the energy
+increases monotonically as a function of increasing gain, and the losses become
+increasingly larger with increasing energy, i.e. there are many routes for
+dissipation in the system for large input energy. The intersection of the gain
+and loss curves define an energy balanced solution. By constructing an
+iterative map between the loss and gain curves, the dynamics can be shown to be
+homeomorphic to the logistic map, which exhibits a period doubling cascade to
+chaos. Indeed, the loss and gain curves allow for a geometrical description of
+the dynamics through a simple Verhulst diagram (cobweb plot). Thus irrespective
+of the physics and its complexities, this simple geometrical description
+dictates the universal set of logistic map instabilities that arise in complex
+damped-driven systems. More broadly, damped-driven systems are a class of
+non-equilibrium pattern forming systems which have a canonical set of
+instabilities that are manifest in practice.",2211.11748v1
+2023-01-23,Optimal Inter-area Oscillation Damping Control: A Transfer Deep Reinforcement Learning Approach with Switching Control Strategy,"Wide-area damping control for inter-area oscillation (IAO) is critical to
+modern power systems. The recent breakthroughs in deep learning and the broad
+deployment of phasor measurement units (PMU) promote the development of
+datadriven IAO damping controllers. In this paper, the damping control of IAOs
+is modeled as a Markov Decision Process (MDP) and solved by the proposed Deep
+Deterministic Policy Gradient (DDPG) based deep reinforcement learning (DRL)
+approach. The proposed approach optimizes the eigenvalue distribution of the
+system, which determines the IAO modes in nature. The eigenvalues are evaluated
+by the data-driven method called dynamic mode decomposition. For a given power
+system, only a subset of generators selected by participation factors needs to
+be controlled, alleviating the control and computing burdens. A Switching
+Control Strategy (SCS) is introduced to improve the transient response of IAOs.
+Numerical simulations of the IEEE-39 New England power grid model validate the
+effectiveness and advanced performance of the proposed approach as well as its
+robustness against communication delays. In addition, we demonstrate the
+transfer ability of the DRL model trained on the linearized power grid model to
+provide effective IAO damping control in the non-linear power grid model
+environment.",2301.09321v1
+2023-04-13,Centralised Multimode Power Oscillation Damping Controller for Photovoltaic Plants with Communication Delay Compensation,"Low-frequency oscillations are an inherent phenomena in transmission networks
+and renewable energy plants should be configured to damp them. Commonly, a
+centralised controller is used in PV plants to coordinate PV generators via
+communication channels. However, the communication systems of PV plants
+introduce delays of a stochastic nature that degrade the performance of
+centralised control algorithms. Therefore, controllers for oscillation damping
+may not operate correctly unless the communication channel characteristics are
+not considered and compensated. In this paper, a centralised controller is
+proposed for the oscillation damping that uses a PV plant with all the
+realistic effects of communication channels taken into consideration. The
+communication channels are modelled based on measurements taken in a laboratory
+environment. The controller is designed to damp several modes of oscillation by
+using the open-loop phase shift compensation. Theoretical developments were
+validated in a laboratory using four converters acting as two PV inverters, a
+battery and a STATCOM. A real-time processing platform was used to implement
+the centralised controller and to deploy the communication infrastructure.
+Experimental results show the communication channels impose severe restrictions
+on the performance of centralised POD controllers, highlighting the importance
+of their accurate modelling and consideration during the controller design
+stage.",2304.06415v1
+2023-05-09,Glassy heat capacity from overdamped phasons and a hypothetical phason-induced superconductivity in incommensurate structures,"Phasons are collective low-energy modes that appear in disparate condensed
+matter systems such as quasicrystals, incommensurate structures, fluctuating
+charge density waves, and Moir\'e superlattices. They share several
+similarities with acoustic phonon modes, but they are not protected by any
+exact translational symmetry. As a consequence, they are subject to a
+wavevector independent damping, and they develop a finite pinning frequency,
+which destroy their acoustic linearly propagating dispersion. Under a few and
+simple well-motivated assumptions, we compute the phason density of states, and
+we derive the phason heat capacity as a function of the temperature. Finally,
+imagining a hypothetical s-wave pairing channel with electrons, we compute the
+critical temperature $T_c$ of the corresponding superconducting state as a
+function of phason damping using the Eliashberg formalism. We find that for
+large phason damping, the heat capacity is linear in temperature, showing a
+distinctive glass-like behavior. Additionally, we observe that the phason
+damping can strongly enhance the effective Eliashberg coupling, and we reveal a
+sharp non-monotonic dependence of the superconducting temperature $T_c$ on the
+phason damping, with a maximum located at the underdamped to overdamped
+crossover scale. Our simple computations confirm the potential role of
+overdamped modes in explaining the glassy properties of incommensurate
+structures, but also in possibly inducing strongly-coupled superconductivity
+therein, and enhancing the corresponding $T_c$.",2305.05407v2
+2023-08-03,Flavor-wave theory with quasiparticle damping at finite temperatures: Application to chiral edge modes in the Kitaev model,"We propose a theoretical framework to investigate elementary excitations at
+finite temperatures within a localized electron model that describes the
+interactions between multiple degrees of freedom, such as quantum spin models
+and Kugel-Khomskii models. Thus far, their excitation structures have been
+mainly examined using the linear flavor-wave theory, an SU($N$) generalization
+of the linear spin-wave theory. These techniques introduce noninteracting
+bosonic quasiparticles as elementary excitations from the ground state, thereby
+elucidating numerous physical phenomena, including excitation spectra and
+transport properties characterized by topologically nontrivial band structures.
+Nevertheless, the interactions between quasiparticles cannot be ignored in
+systems exemplified by $S=1/2$ quantum spin models, where strong quantum
+fluctuations are present. Recent studies have investigated the effects of
+quasiparticle damping at zero temperature in such models. In our study,
+extending this approach to the flavor-wave theory for general localized
+electron models, we construct a comprehensive method to calculate excitation
+spectra with the quasiparticle damping at finite temperatures. We apply our
+method to the Kitaev model under magnetic fields, a typical example of models
+with topologically nontrivial magnon bands. Our calculations reveal that chiral
+edge modes undergo significant damping in weak magnetic fields, amplifying the
+damping rate by the temperature increase. This effect is caused by collisions
+with thermally excited quasiparticles. Since our approach starts from a general
+Hamiltonian, it will be widely applicable to other localized systems, such as
+spin-orbital coupled systems derived from multi-orbital Hubbard models in the
+strong correlation limit.",2308.01711v1
+2024-02-13,Investigating the Effect of Noise on the Training Performance of Hybrid Quantum Neural Networks,"In this paper, we conduct a comprehensively analyze the influence of
+different quantum noise gates, including Phase Flip, Bit Flip, Phase Damping,
+Amplitude Damping, and the Depolarizing Channel, on the performance of HyQNNs.
+Our results reveal distinct and significant effects on HyQNNs training and
+validation accuracies across different probabilities of noise. For instance,
+the Phase Flip gate introduces phase errors, and we observe that HyQNNs exhibit
+resilience at higher probability (p = 1.0), adapting effectively to consistent
+noise patterns, whereas at intermediate probabilities, the performance
+declines. Bit Flip errors, represented by the PauliX gate, impact HyQNNs in a
+similar way to that Phase Flip error gate. The HyQNNs, can adapt such kind of
+errors at maximum probability (p = 1.0). Unlike Phase and Bit Flip error gates,
+Phase Damping and Amplitude Damping gates disrupt quantum information, with
+HyQNNs demonstrating resilience at lower probabilities but facing challenges at
+higher probabilities. Amplitude Damping error gate, in particular, poses
+efficiency and accuracy issues at higher probabilities however with lowest
+probability (p = 0.1),it has the least effect and the HyQNNs, however not very
+effectively, but still tends to learn. The Depolarizing Channel proves most
+detrimental to HyQNNs performance, with limited or no training improvements.
+There was no training potential observed regardless of the probability of this
+noise gate. These findings underscore the critical need for advanced quantum
+error mitigation and resilience strategies in the design and training of
+HyQNNs, especially in environments prone to depolarizing noise. This paper
+quantitatively investigate that understanding the impact of quantum noise gates
+is essential for harnessing the full potential of quantum computing in
+practical applications.",2402.08523v1
+2024-03-03,Magnonic $\varphi$ Josephson Junctions and Synchronized Precession,"There has been a growing interest in non-Hermitian physics. One of its main
+goals is to engineer dissipation and to explore ensuing functionality. In
+magnonics, the effect of dissipation due to local damping on magnon transport
+has been explored. However, the effects of non-local damping on the magnonic
+analog of the Josephson effect remain missing, despite that non-local damping
+is inevitable and has been playing a central role in magnonics. Here, we
+uncover theoretically that a surprisingly rich dynamics can emerge in magnetic
+junctions due to intrinsic non-local damping, using analytical and numerical
+methods. In particular, under microwave pumping, we show that coherent spin
+precession in the right and left insulating ferromagnet (FM) of the junction
+becomes synchronized by non-local damping and thereby a magnonic analog of the
+$\varphi$ Josephson junction emerges, where $\varphi$ stands here for the
+relative precession phase of right and left FM in the stationary limit.
+Remarkably, $\varphi$ decreases monotonically from $ \pi$ to $\pi/2$ as the
+magnon-magnon interaction, arising from spin anisotropies, increases. Moreover,
+we also find a magnonic diode effect giving rise to rectification of magnon
+currents. Our predictions are readily testable with current device and
+measurement technologies at room temperatures.",2403.01625v1
+2003-03-03,Sur une generalisation des coefficients binomiaux,"We prove a recent conjecture of Lassalle about positivity and integrality of
+coefficients in some polynomial expansions. We also give a combinatorial
+interpretation of those numbers. Finally, we show that this question is closely
+related to the fundamental problem of calculating the linearization
+coefficients for binomial coefficients.",0303025v1
+2013-06-18,Estimating Certain Non-Zero Littlewood-Richardson Coefficients,"Littlewood Richardson coefficients are structure constants appearing in the
+representation theory of the general linear groups ($GL_n$). The main results
+of this paper are: 1. A strongly polynomial randomized approximation scheme for
+certain Littlewood-Richardson coefficients. 2. A proof of approximate
+log-concavity of certain Littlewood-Richardson coefficients.",1306.4060v1
+2014-10-29,Rectangular symmetries for coefficients of symmetric functions,"We show that some of the main structural constants for symmetric functions
+(Littlewood-Richardson coefficients, Kronecker coefficients, plethysm
+coefficients, and the Kostka--Foulkes polynomials) share symmetries related to
+the operations of taking complements with respect to rectangles and adding
+rectangles.",1410.8017v1
+2020-02-03,The Computational Complexity of Plethysm Coefficients,"In two papers, B\""urgisser and Ikenmeyer (STOC 2011, STOC 2013) used an
+adaption of the geometric complexity theory (GCT) approach by Mulmuley and
+Sohoni (Siam J Comput 2001, 2008) to prove lower bounds on the border rank of
+the matrix multiplication tensor. A key ingredient was information about
+certain Kronecker coefficients. While tensors are an interesting test bed for
+GCT ideas, the far-away goal is the separation of algebraic complexity classes.
+The role of the Kronecker coefficients in that setting is taken by the
+so-called plethysm coefficients: These are the multiplicities in the coordinate
+rings of spaces of polynomials. Even though several hardness results for
+Kronecker coefficients are known, there are almost no results about the
+complexity of computing the plethysm coefficients or even deciding their
+positivity.
+  In this paper we show that deciding positivity of plethysm coefficients is
+NP-hard, and that computing plethysm coefficients is #P-hard. In fact, both
+problems remain hard even if the inner parameter of the plethysm coefficient is
+fixed. In this way we obtain an inner versus outer contrast: If the outer
+parameter of the plethysm coefficient is fixed, then the plethysm coefficient
+can be computed in polynomial time.
+  Moreover, we derive new lower and upper bounds and in special cases even
+combinatorial descriptions for plethysm coefficients, which we consider to be
+of independent interest. Our technique uses discrete tomography in a more
+refined way than the recent work on Kronecker coefficients by Ikenmeyer,
+Mulmuley, and Walter (Comput Compl 2017). This makes our work the first to
+apply techniques from discrete tomography to the study of plethysm
+coefficients. Quite surprisingly, that interpretation also leads to new
+equalities between certain plethysm coefficients and Kronecker coefficients.",2002.00788v1
+2007-06-04,Bounds for Hilbert coefficients,"We compute the Hilbert coefficients of a graded module with pure resolution
+and discuss lower and upper bounds for these coefficients for arbitrary graded
+modules.",0706.0400v1
+2020-06-23,Recurrence relations of Li coefficients,"One of equivalents of the Riemann hypothesis is Li's criterion that all Li
+coefficients are positive. We study recurrence relations of Li coefficients in
+this note.",2006.13103v1
+2007-05-02,The Truth About Ballistic Coefficients,"The ballistic coefficient of a bullet describes how it slows in flight due to
+air resistance. This article presents experimental determinations of ballistic
+coefficients showing that the majority of bullets tested have their previously
+published ballistic coefficients exaggerated from 5-25% by the bullet
+manufacturers. These exaggerated ballistic coefficients lead to inaccurate
+predictions of long range bullet drop, retained energy and wind drift.",0705.0389v1
+2008-12-11,Lorentz Violation and Alpha-Decay,"Relating the effective Lorentz violation coefficients for composite particles
+to the coefficients for their constituent fields is a challenging problem. We
+calculate the Lorentz violation coefficients relevant to the dynamics of an
+alpha-particle in terms of proton and neutron coefficients. The alpha-particle
+coefficients would lead to anisotropies in the alpha-decays of nuclei, and
+because the decay process involves quantum tunneling, the effects of any
+Lorentz violations could be exponentially enhanced.",0812.2236v1
+2010-09-28,Absolute continuity under flows generated by SDE with measurable drift coefficient,"We consider the It\^{o} SDE with non-degenerate diffusion coefficient and
+measurable drift coefficient. Under the condition that the gradient of the
+diffusion coefficient and the divergences of the diffusion and drift
+coefficients are exponentially integrable with respect to the Gaussian measure,
+we show that the stochastic flow leaves the reference measure absolutely
+continuous.",1009.5525v1
+2016-01-03,BCJ Relations for One-Loop QCD Integral Coefficients,"We present a set of one-loop integral coefficient relations in QCD. The
+unitarity method is useful for exposing one-loop amplitudes in terms of tree
+amplitudes. The coefficient relations are induced by tree-level BCJ amplitude
+relations. We provide examples for box, triangle, and bubble coefficients.
+These relations reduce the total number of independent coefficients needed to
+calculate one-loop QCD amplitudes.",1601.00235v1
+2017-03-10,On Coefficient problem for bi-univalent analytic functions,"Estimates for initial coefficients of Taylor-Maclaurin series of bi-univalent
+functions belonging to certain classes defined by subordination are obtained.
+Our estimates improve upon the earlier known estimates for second and third
+coefficient. The bound for the fourth coefficient is new. In addition, bound
+for the fifth coefficient is obtained for bi-starlike and strongly bi-starlike
+functions of order $\rho$ and $\beta$ respectively.",1703.03598v1
+2023-05-09,Saturation for Flagged Skew Littlewood-Richardson Coefficients,"We define and study a generalization of the Littlewood-Richardson (LR)
+coefficients, which we call the flagged skew LR coefficients. These subsume
+several previously studied extensions of the LR coefficients. We establish the
+saturation property for these coefficients, generalizing work of Knutson-Tao
+and Kushwaha-Raghavan-Viswanath.",2305.05195v2
+2023-06-11,Extreme coefficients of multiplicity Tutte polynomials,"The multiplicity Tutte polynomial, which includes the arithmetic Tutte
+polynomial, is a generalization of the classical Tutte polynomial of matroids.
+In this paper, we obtain an expression of the general coefficient and the
+expressions of six extreme coefficients of multiplicity Tutte polynomials. In
+particular, an expression of the general coefficient and the expressions of
+corresponding extreme coefficients of classical Tutte polynomial of matroids
+are deduced.",2306.06568v2
+2023-09-10,Testing for Stationary or Persistent Coefficient Randomness in Predictive Regressions,"This study considers tests for coefficient randomness in predictive
+regressions. Our focus is on how tests for coefficient randomness are
+influenced by the persistence of random coefficient. We find that when the
+random coefficient is stationary, or I(0), Nyblom's (1989) LM test loses its
+optimality (in terms of power), which is established against the alternative of
+integrated, or I(1), random coefficient. We demonstrate this by constructing
+tests that are more powerful than the LM test when random coefficient is
+stationary, although these tests are dominated in terms of power by the LM test
+when random coefficient is integrated. This implies that the best test for
+coefficient randomness differs from context to context, and practitioners
+should take into account the persistence of potentially random coefficient and
+choose from several tests accordingly. We apply tests for coefficient constancy
+to real data. The results mostly reverse the conclusion of an earlier empirical
+study.",2309.04926v3
+2004-10-24,Note on the generalized Hansen and Laplace coefficients,"Recently, Breiter et al (2004) reported the computation of Hansen
+coefficients $X_k^{\gamma,m}$ for non integer values of $\gamma$. In fact, the
+Hansen coefficients are closely related to the Laplace $b_{s}^{(m)}$, and
+generalized Laplace coefficients $b_{s,r}^{(m)}$ (Laskar and Robutel, 1995)
+that do not require $s,r$ to be integers. In particular, the coefficients
+$X_0^{\g,m}$ have very simple expressions in terms of the usual Laplace
+coefficients $b_{\g+2}^{(m)}$, and all their properties derive easily from the
+known properties of the Laplace coefficients.",0410557v2
+2010-10-19,Coefficient convexity of divisors of x^n-1,"We say a polynomial f having integer coefficients is strongly coefficient
+convex if the set of coefficients of f consists of consecutive integers only.
+We establish various results suggesting that the divisors of x^n-1 with integer
+coefficients have the tendency to be strongly coefficient convex and have small
+coefficients. The case where n=p^2*q with p and q primes is studied in detail.",1010.3938v2
+2013-10-15,Measuring correlations between non-stationary series with DCCA coefficient,"In this short report, we investigate the ability of the DCCA coefficient to
+measure correlation level between non-stationary series. Based on a wide Monte
+Carlo simulation study, we show that the DCCA coefficient can estimate the
+correlation coefficient accurately regardless the strength of non-stationarity
+(measured by the fractional differencing parameter $d$). For a comparison, we
+also report the results for the standard Pearson's correlation coefficient. The
+DCCA coefficient dominates the Pearson's coefficient for non-stationary series.",1310.3984v1
+2019-07-18,Horn inequalities for nonzero Kronecker coefficients,"The Kronecker coefficients and the Littlewood-Richardson coefficients are
+nonnegative integers depending on three partitions. By definition, these
+coefficients are the multiplicities of the tensor product decomposition of two
+irreducible representations of symmetric groups (resp. linear groups). By a
+classical Littlewood-Murnaghan's result the Kronecker coefficients extend the
+Littlewood-Richardson ones.The nonvanishing of a Littlewood-Richardson
+coefficient implies linear inequalities on the triple of partitions, called
+Horn inequalities. In thispaper, we extend the essential Horn inequalities to
+the triples of partitions corresponding to a nonzero Kronecker coefficient.",1907.07931v1
+2022-12-13,Interaction phenomenon for variable coefficient Kadomtsev-Petviashvili equation by utilizing variable coefficient bilinear neural network method,"In this paper, a variable coefficient Bilinear neural network method is
+proposed to deal with the analytical solutions of variable coefficient
+nonlinear partial differential equations. As an example, a
+Kadomstev-Petviashvili equation with variable coefficients is investigated by
+using the variable coefficient Bilinear neural network method. By establishing
+""3-2-2-1"" and ""3-3-2-1"" models respectively, rich analytical solutions of the
+variable coefficient Kadomstev-Petviashvili equation are obtained. By choosing
+some special values of the parameters, the dynamics properties are demonstrated
+in some three-dimensional and density graphics.",2301.10069v1
+2023-08-22,Sharp bounds on Coefficient functionals of certain Sakaguchi functions,"We determine sharp bounds on some Hankel determinants involving initial
+coefficients, inverse coefficients, and logarithmic inverse coefficients for
+two subclasses of Sakaguchi functions which are associated with the right half
+of the lemniscate of Bernoulli and the exponential function. Further, we
+compute sharp bounds on the second Hermitian-Toeplitz determinants involving
+logarithmic coefficients and logarithmic inverse coefficients. We also discuss
+invariant property for the obtained estimates with respect to various
+coefficients.",2308.11352v1
+2023-12-22,Asymptotic coefficients of multiple zeta functions at the origin and generalized Gregory coefficients,"Due to their singularities, multiple zeta functions behave sensitively at
+non-positive integer points. In this article, we focus on the asymptotic
+behavior at the origin $(0,\dots, 0)$ and unveil the generating series of the
+asymptotic coefficients as a generalization of the classical Gregory
+coefficients. This enables us to reveal the underlying symmetry of the
+asymptotic coefficients. Additionally, we extend the relationship between the
+asymptotic coefficients and the Gregory coefficients to include Hurwitz
+multiple zeta functions.",2312.14475v1
+1997-01-17,Evidence for Rotation in the Galaxy at z=3.15 Responsible for a Damped Lyman-alpha Absorption System in the Spectrum of Q2233+1310,"Proof of the existence of a significant population of normal disk galaxies at
+redshift z>2 would have profound implications for theories of structure
+formation and evolution. We present evidence based on Keck HIRES observations
+that the damped Lyman-alpha absorber at z=3.15 toward the quasar Q2233+1310 may
+well be such an example. Djorgovski et al have recently detected the
+Lyman-alpha emission from the absorber, which we assume is at the systemic
+redshift of the absorbing galaxy. By examining the profiles of the metal
+absorption lines arising from the absorbing galaxy in relation to its systemic
+redshift, we find strong kinematical evidence for rotation. Therefore the
+absorber is likely to be a disk galaxy. The inferred circular velocity for the
+galaxy is >200 km/s. With a separation of ~17 kpc between the galaxy and the
+quasar sightline, the implied dynamic mass for the galaxy is >1.6x10(11) solar
+mass. The metallicity of the galaxy is found to be [Fe/H]=-1.4, typical of
+damped Lyman-alpha galaxies at such redshifts. However, in another damped
+galactic rotation is evident. In the latter case, the damped Lyman-alpha
+absorber occurs near the background quasar in redshift so its properties may be
+influenced by the background quasar. These represent the only two cases at
+present for which the technique used here may be applied. Future applications
+of the same technique to a large sample of damped Lyman-alpha galaxies may
+allow us to determine if a significant population of disk galaxies already
+existed only a few billion years after the Big Bang.",9701116v2
+1997-04-11,The Metallicity of High Redshift Galaxies: The Abundance of Zinc in 34 Damped Lyman Alpha Systems from z = 0.7 to 3.4,"We report new observations of ZnII and CrII absorption lines in 10 damped
+\lya systems (DLAs), mostly at redshift $z_{abs} \simgt 2.5$ . By combining
+these results with those from our earlier survey (Pettini et al. 1994) and
+other recent data, we construct a sample of 34 measurements (or upper limits)
+of the Zn abundance relative to hydrogen [Zn/H]; the sample includes more than
+one third of the total number of DLAs known.
+  The plot of the abundance of Zn as a function of redshift reinforces the two
+main findings of our previous study. (1) Damped \lya systems are mostly
+metal-poor, at all redshifts sampled; the column density weighted mean for the
+whole data set is [Zn/H] $= -1.13 \pm 0.38$ (on a logarithmic scale), or
+approximately 1/13 of solar. (2) There is a large spread, by up to two orders
+of magnitude, in the metallicities we measure at essentially the same
+redshifts. We propose that damped \lya systems are drawn from a varied
+population of galaxies of different morphological types and at different stages
+of chemical evolution, supporting the idea of a protracted epoch of galaxy
+formation.
+  At redshifts $z \simgt 2$ the typical metallicity of the damped \lya systems
+is in agreement with expectations based on the consumption of HI gas implied by
+the recent measurements of $\Omega_{DLA}$ by Storrie-Lombardi et al. (1996a),
+and with the metal ejection rates in the universe at these epochs deduced by
+Madau (1996) from the ultraviolet luminosities of high redshift galaxies
+revealed by deep imaging surveys. There are indications in our data for an
+increase in the mean metallicity of the damped \lya systems from $z > 3$ to
+$\approx 2$, consistent with the rise in the comoving star formation rate
+indicated by the relative numbers of $U$ and $B$ drop-outs in the Hubble Deep
+Field. Although such comparisons are still tentative, it appears that these
+different avenues for exploring the early evolution of galaxies give a broadly
+consistent picture.",9704102v1
+1997-04-17,On the Kinematics of the Damped Lyman Alpha Protogalaxies,"We present the first results of an ongoing program to investigate the
+kinematic characteristics of high redshift damped lya systems. Because damped
+lya systems are widely believed to be the progenitors of current massive
+galaxies, an analysis of their kinematic history allows a direct test of galaxy
+formation scenarios.
+  We have collected a kinematically unbiased sample of 17 high S/N ratio, high
+resolution damped lya spectra taken with HIRES on the 10m W.M. Keck Telescope.
+Our study focuses on the unsaturated, low-ion transitions of these systems
+which reveal their kinematic traits. The profiles exhibit a nearly uniform
+distribution of velocity widths ranging from 20 - 200 km/s and a relatively
+high degree of asymmetry. In an attempt to explain these characteristics, we
+introduce several physical models, which have previously been attributed to
+damped lya systems, including rapidly rotating cold disks, slowly rotating hot
+disks, massive isothermal halos, and a hydrodynamic spherical accretion model.
+  Using standard Monte Carlo techniques, we run sightlines through these model
+systems to derive simulated low-ion profiles. Comparing statistical measures of
+the simulated profiles with the observed profiles, we determine that the
+rapidly rotating cold disk model is the only tested model consistent with the
+data at high confidence levels. A Relative Likelihood Test of the rapidly
+rotating cold disk model indicates the disks must have large rotation speeds; v
+> 180 km/s at the 99% c.l. In turn, we demonstrate that the Cold Dark Matter
+Model, as developed by Kauffmann (1996), is inconsistent with the damped lya
+data at very high c.l. This is because the CDM Model does not predict a large
+enough fraction of rapidly rotating disks at z approx 2.5.",9704169v2
+2000-11-20,H-alpha Imaging with HST+NICMOS of An Elusive Damped Ly-alpha Cloud at z=0.6,"Despite previous intensive ground-based imaging and spectroscopic campaigns
+and wide-band HST imaging of the z=0.927 QSO 3C336 field, the galaxy that hosts
+the damped Ly-alpha system along this line-of-sight has eluded detection. We
+present a deep narrow-band H-alpha image of the field of this z=0.656 damped
+Ly-alpha absorber, obtained through the F108N filter of NICMOS 1 onboard the
+Hubble Space Telescope. The goal of this project was to detect any H-alpha
+emission 10 times closer than previous studies to unveil the damped absorber.
+We do not detect H-alpha emission between 0.05'' and 6'' (0.24 and 30 $h^{-1}$
+kpc) from the QSO, with a 3-sigma flux limit of $3.70 \times 10^{-17} h^{-2}$
+erg/s/cm^2 for an unresolved source, corresponding to a star formation rate
+(SFR) of $0.3 h^{-2}$ M_sun/yr. This leads to a 3-sigma upper limit of 0.15
+M_sun/yr/kpc^2 on the SFR density, or a maximum SFR of 1.87 M_sun/yr assuming a
+disk of 4 kpc in diameter. This result adds to the number of low redshift
+damped Ly-alpha absorbers that are not associated with the central regions of
+Milky-Way-like disks. Damped Ly-alpha absorption can arise from high density
+concentrations in a variety of galactic environments including some that,
+despite their high local HI densities, are not conducive to widespread star
+formation.",0011374v2
+2005-08-17,The SDSS Damped Lya Survey: Data Release 3,"We present the results from a damped Lya survey of the Sloan Digital Sky
+Survey, Data Release 3 based on over 500 new damped Lya systems at z>2.2. We
+measure the HI column density distribution f(N) and its zeroth and first
+moments (the incidence l(X) and gas mass-density O_dla of damped Lya systems,
+respectively) as a function of redshift. The key results include: (1) the f(N)
+distribution is well fit by a Gamma-function with `break' column density log
+N_g=10^21.5 and `faint-end' slope alpha=-1.8; (2) the shape of the f(N)
+distributions do not show evolution with redshift; (3) l(X) and O_dla decrease
+by 35% and 50% during ~1Gyr between redshift z=[3.,3.5] to z=[2.2,2.5]; and (4)
+l(X) and O_dla in the lowest SDSS redshift bin (z=2.2) are consistent with the
+current values. We investigate systematic errors in damped Lya analysis and
+identify only one important effect: we measure 40 +/- 20% higher O_dla values
+toward a subset of brighter quasars than toward a faint subset. This effect
+runs contrary to the bias associated with dust obscuration and suggests that
+gravitational lensing may be important. Comparing the results against models of
+galaxy formation, we find all of the models significantly underpredict l(X) at
+z=3 and only SPH models with significant feedback may reproduce O_dla at high
+redshift. We argue that the Lyman limit systems contribute ~1/3 of the
+universe's HI atoms at all redshifts z=2 to 5 and that the f(N) distribution
+for N(HI)<10^20 has an inflection with slope >-1. We advocate a new mass
+density definition -- the mass density of predominantly neutral gas O_neut --
+to be contrasted with the mass density of gas associated with HI atoms. We
+contend the damped Lya systems contribute >80% of O_neut at all redshifts and
+therefore are the main reservoirs for star formation. [abridged]",0508361v1
+2011-09-07,Weakly collisional Landau damping and three-dimensional Bernstein-Greene-Kruskal modes: New results on old problems,"Landau damping and Bernstein-Greene-Kruskal (BGK) modes are among the most
+fundamental concepts in plasma physics. While the former describes the
+surprising damping of linear plasma waves in a collisionless plasma, the latter
+describes exact undamped nonlinear solutions of the Vlasov equation. There does
+exist a relationship between the two: Landau damping can be described as the
+phase-mixing of undamped eigenmodes, the so-called Case-Van Kampen modes, which
+can be viewed as BGK modes in the linear limit. While these concepts have been
+around for a long time, unexpected new results are still being discovered. For
+Landau damping, we show that the textbook picture of phase-mixing is altered
+profoundly in the presence of collision. In particular, the continuous spectrum
+of Case-Van Kampen modes is eliminated and replaced by a discrete spectrum,
+even in the limit of zero collision. Furthermore, we show that these discrete
+eigenmodes form a complete set of solutions. Landau-damped solutions are then
+recovered as true eigenmodes (which they are not in the collisionless theory).
+For BGK modes, our interest is motivated by recent discoveries of electrostatic
+solitary waves in magnetospheric plasmas. While one-dimensional BGK theory is
+quite mature, there appear to be no exact three-dimensional solutions in the
+literature (except for the limiting case when the magnetic field is
+sufficiently strong so that one can apply the guiding-center approximation). We
+show, in fact, that two- and three-dimensional solutions that depend only on
+energy do not exist. However, if solutions depend on both energy and angular
+momentum, we can construct exact three-dimensional solutions for the
+unmagnetized case, and two-dimensional solutions for the case with a finite
+magnetic field. The latter are shown to be exact, fully electromagnetic
+solutions of the steady-state Vlasov-Poisson-Amp\`ere system.",1109.1353v1
+2013-05-16,Application of vibration-transit theory to distinct dynamic response for a monatomic liquid,"We examine the distinct part of the density autocorrelation function Fd(q,t),
+also called the intermediate scattering function, from the point of view of the
+vibration-transit (V-T) theory of monatomic liquid dynamics. A similar study
+has been reported for the self part, and we study the self and distinct parts
+separately because their damping processes are not simply related. We begin
+with the perfect vibrational system, which provides precise definitions of the
+liquid correlations, and provides the vibrational approximation Fdvib(q,t) at
+all q and t. Two independent liquid correlations are defined, motional and
+structural, and these are decorrelated sequentially, with a crossover time
+tc(q). This is done by two independent decorrelation processes: the first,
+vibrational dephasing, is naturally present in Fdvib(q,t) and operates to damp
+the motional correlation; the second, transit-induced decorrelation, is invoked
+to enhance the damping of motional correlation, and then to damp the structural
+correlation. A microscopic model is made for the ""transit drift"", the averaged
+transit motion that damps motional correlation on 0 < t < tc(q). Following the
+previously developed self-decorrelation theory, a microscopic model is also
+made for the ""transit random walk,"" which damps the structural correlation on t
+> tc(q). The complete model incorporates a property common to both self and
+distinct decorrelation: simple exponential decay following a delay period,
+where the delay is tc(q, the time required for the random walk to emerge from
+the drift. Our final result is an accurate expression for Fd(q,t) for all q
+through the first peak in Sd(q). The theory is calibrated and tested using
+molecular dynamics (MD) calculations for liquid Na at 395K; however, the theory
+itself does not depend on MD, and we consider other means for calibrating it.",1305.3954v2
+2013-09-16,Two-atom system as a nano-antenna for mode switching and light routing,"We determine how a system composed of two nonidentical two-level atoms with
+different resonance frequencies and different damping rates could work as a
+nano-antenna for controlled mode switching and light routing. We calculate the
+angular distribution of the emitted field detected in a far-field zone of the
+system including the direct interatomic interactions and arbitrary linear
+dimensions of the system. The calculation is carried out in terms of the
+symmetric and antisymmetric modes of the two atom system. We find that as long
+as the atoms are identical, the emission cannot be switched between the
+symmetric and antisymmetric modes. The switching may occur when the atoms are
+non-identical and the emission can then be routed to different modes by
+changing the relative ratio of the atomic frequencies, or damping rates or by a
+proper tuning of the laser frequency to the atomic resonance frequencies. It is
+shown that in the case of atoms of different resonance frequencies but equal
+damping rates, the light routing is independent of the frequency of the driving
+laser field. It depends only on the sign of the detuning between the atomic
+resonance frequencies. In the case of atoms of different damping rates, the
+emission can be switched between different modes by changing the laser
+frequency from the blue to red detuned from the atomic resonance. The effect of
+the interatomic interactions is also considered and it is found that in the
+case of unequal resonance frequencies of the atoms, the interactions slightly
+modify the visibility of the intensity pattern. The case of unequal damping
+rates of the atoms is affected rather more drastically, the light routing
+becoming asymmetric under the dipole-dipole interaction with the enhanced
+intensities of the modes turned towards the atom of smaller damping rate.",1309.3924v1
+2015-04-01,Landau damping of Gardner solitons in a dusty bi-ion plasma,"The effects of linear Landau damping on the nonlinear propagation of
+dust-acoustic solitary waves (DASWs) are studied in a collisionless
+unmagnetized dusty plasma with two species of positive ions. The extremely
+massive, micron-seized, cold and negatively charged dust particles are
+described by fluid equations, whereas the two species of positive ions, namely
+the cold (heavy) and hot (light) ions are described by the kinetic Vlasov
+equations. Following Ott and Sudan [Phys. Fluids {\bf 12}, 2388 (1969)], and by
+considering lower and higher-order perturbations, the evolution of DASWs with
+Landau damping is shown to be governed by Korteweg-de Vries (KdV), modified KdV
+(mKdV) or Gardner (KdV-mKdV)-like equations. The properties of the phase
+velocity and the Landau damping rate of DASWs are studied for different values
+of the ratios of the temperatures $(\sigma)$ and the number densities $(\mu)$
+of hot and cold ions as well the cold to hot ion mass ratio $m$. The
+distinctive features of the decay rates of the amplitudes of the KdV, mKdV and
+Gardner solitons with a small effect of Landau damping are also studied in
+different parameter regimes. It is found that the Gardner soliton points to
+lower wave amplitudes than the KdV and mKdV solitons. The results may be useful
+for understanding the localization of solitary pulses and associated wave
+damping (collisionless) in laboratory and space plasmas (e.g., the F-ring of
+Saturn) in which the number density of free electrons is much smaller than that
+of ions and the heavy, micron seized dust grains are highly charged.",1504.00089v2
+2017-07-18,Explanations of the DAMPE high energy electron/positron spectrum in the dark matter annihilation and pulsar scenarios,"Many studies have shown that either the nearby astrophysical source or dark
+matter (DM) annihilation/decay is required to explain the origin of high energy
+cosmic ray (CR) $e^\pm$, which are measured by many experiments, such as PAMELA
+and AMS-02. Recently, the Dark Matter Particle Explorer (DAMPE) collaboration
+has reported its first result of the total CR $e^\pm$ spectrum from $25
+\,\mathrm{GeV}$ to $4.6 \,\mathrm{TeV}$ with high precision. In this work, we
+study the DM annihilation and pulsar interpretations of the DAMPE high energy
+$e^\pm$ spectrum. In the DM scenario, the leptonic annihilation channels to
+$\tau^+\tau^-$, $4\mu$, $4\tau$, and mixed charged lepton final states can well
+fit the DAMPE result, while the $\mu^+\mu^-$ channel has been excluded. In
+addition, we find that the mixed charged leptons channel would lead to a sharp
+drop at $\sim$ $\mathrm{TeV}$. However, these DM explanations are almost
+excluded by the observations of gamma-ray and CMB, unless some complicated DM
+models are introduced. In the pulsar scenario, we analyze 21 nearby known
+pulsars and assume that one of them is the primary source of high energy CR
+$e^\pm$.Considering the constraint from the Fermi-LAT observation of the
+$e^\pm$ anisotropy, we find that two pulsars are possible to explain the DAMPE
+data. Our results show that it is difficult to distinguish between the DM
+annihilation and single pulsar explanations of high energy $e^\pm$ with the
+current DAMPE result.",1707.05664v2
+2018-06-27,In-flight performance of the DAMPE silicon tracker,"DAMPE (DArk Matter Particle Explorer) is a spaceborne high-energy cosmic ray
+and gamma-ray detector, successfully launched in December 2015. It is designed
+to probe astroparticle physics in the broad energy range from few GeV to 100
+TeV. The scientific goals of DAMPE include the identification of possible
+signatures of Dark Matter annihilation or decay, the study of the origin and
+propagation mechanisms of cosmic-ray particles, and gamma-ray astronomy. DAMPE
+consists of four sub-detectors: a plastic scintillator strip detector, a
+Silicon-Tungsten tracKer-converter (STK), a BGO calorimeter and a neutron
+detector. The STK is composed of six double layers of single-sided silicon
+micro-strip detectors interleaved with three layers of tungsten for photon
+conversions into electron-positron pairs. The STK is a crucial component of
+DAMPE, allowing to determine the direction of incoming photons, to reconstruct
+tracks of cosmic rays and to estimate their absolute charge (Z). We present the
+in-flight performance of the STK based on two years of in-flight DAMPE data,
+which includes the noise behavior, signal response, thermal and mechanical
+stability, alignment and position resolution.",1806.10355v1
+2019-03-28,Improving convergence of volume penalised fluid-solid interactions,"We analyse and improve the volume-penalty method, a simple and versatile way
+to model objects in fluid flows. The volume-penalty method is a kind of
+fictitious-domain method that approximates no-slip boundary conditions with
+rapid linear damping inside the object. The method can then simulate complex,
+moving objects in general numerical solvers without specialised algorithms or
+boundary-conforming grids. Volume penalisation pays for this simplicity by
+introducing an equation-level error, the $\textit{model error}$, that is
+related to the damping time $\eta \ll 1$. While the model error has been proven
+to vanish as the damping time tends to zero, previous work suggests convergence
+at a slow rate of $\mathcal{O}(\eta^{1/2})$. The stiffness of the damping
+implies conventional volume penalisation only achieves first order numerical
+accuracy. We analyse the volume-penalty method using multiple-scales
+matched-asymptotics with a signed-distance coordinate system valid for
+arbitrary smooth geometries. We show the dominant model error stems from a
+displacement length that is proportional to a Reynolds number $\text{Re}$
+dependent boundary layer of size $\mathcal{O}(\eta^{1/2}\text{Re}^{-1/2})$. The
+relative size of the displacement length and damping time leads to multiple
+error regimes. Our key finding derives a simple smoothing prescription for the
+damping that eliminates the displacement length and reduces the model error to
+$\mathcal{O}(\eta)$ in all regimes. This translates to second order numerical
+accuracy. We validate our findings in several comprehensive benchmark problems
+and finally combine Richardson extrapolation of the model error with our
+correction to further improve convergence to $\mathcal{O}(\eta^{2})$.",1903.11914v4
+2019-06-12,Study of Alfven Eigenmodes stability in plasma with multiple NBI driven energetic particle specie,"The aim of this study is to analyze the destabilization of Alfven Eigenmodes
+(AE) by multiple energetic particles (EP) species in DIII-D and LHD discharges.
+We use the reduced MHD equations to describe the linear evolution of the
+poloidal flux and the toroidal component of the vorticity in a full 3D system,
+coupled with equations of density and parallel velocity moments for the
+energetic particles species, including the effect of the acoustic modes,
+diamagnetic currents and helical couplings. We add the Landau damping and
+resonant destabilization effects using a closure relation. The simulations with
+multiple NBI lines show three different regimes: the non damped regime where
+the multi beam AEs growth rate is larger compared to the growth rate of the AEs
+destabilized by the individual NBI lines, the interaction regime where the
+multi beam AEs growth rate is smaller than the single NBI AEs and the damped
+regime where the AEs are suppressed. Operations in the damped regime requires
+EP species with different density profile flatness or gradient locations. In
+addition, the AEs growth rate in the interaction regime is further reduced if
+the combined NBI lines have similar beam temperatures and the beta of the NBI
+line with flatter EP density profile increases. Then, optimization trends are
+identified in DIII-D high poloidal beta and LHD low density / magnetic field
+discharges with multiple NBI lines as well as the configuration requirements to
+operate in the damped and interaction regimes. DIII-D simulations show a
+decrease of the n=2 to 6 AEs growth rate and n=1 AE are stabilized in the LHD
+case. The helical coupling effects in LHD simulations lead to a transition from
+the interaction to the damped regime of the n=2,-8,12 helical family.",1906.05701v1
+2019-11-05,Observation of Nanoscale Opto-Mechanical Molecular Damping; Origin of Spectroscopic Contrast in Photo Induced Force Microscopy,"We experimentally investigated the contrast mechanism of infrared
+photoinduced force microscopy (PiFM) for recording vibrational resonances.
+Extensive experiments have demonstrated that spectroscopic contrast in PiFM is
+mediated by opto-mechanical damping of the cantilever oscillation as the
+optical wavelength is scanned through optical resonance. To our knowledge, this
+is the first time opto-mechanical damping has been observed in the AFM. We
+hypothesize that this damping force is a consequence of the dissipative
+interaction between the sample and the vibrating tip; the modulated light
+source in PiFM modulates the effective damping constant of the 2nd eigenmode of
+the cantilever which in turn generate side-band signals producing the PiFM
+signal at the 1st eigenmode. A series of experiments have eliminated other
+mechanisms of contrast. By tracking the frequency shift of the PiFM signal at
+the 1st cantilever eigenmode as the excitation wavenumber is tuned through a
+mid-infrared absorption band, we showed that the near-field optical interaction
+is attractive. By using a vibrating piezoelectric crystal to mimic sample
+thermal expansion in a PiFM operating in mixing mode, we determined that the
+minimum thermal expansion our system can detect is 30 pm limited by system
+noise. We have confirmed that van der Waal mediated thermal-expansion forces
+have negligible effect on PiFM signals by detecting the resonant response of a
+4-methylbenzenethiol mono molecular layer deposited on template-stripped gold,
+where thermal expansion was expected to be < 3 pm, i.e., 10 times lower than
+our system noise level. Finally, the basic theory for dissipative tip-sample
+interactions was introduced to model the photoinduced opto-mechanical damping.
+Theoretical simulations are in excellent agreement with experiment.",1911.05190v1
+2020-06-08,Stochastic re-acceleration and magnetic-field damping in Tycho's supernova remnant,"A number of studies suggest that shock acceleration with particle feedback
+and very efficient magnetic-field amplification combined with Alfv\'{e}nic
+drift are needed to explain the rather soft radio spectrum and the narrow rims
+observed for Tycho's SNR. We show that the broadband spectrum of Tycho's SNR
+can alternatively be well explained when accounting for stochastic acceleration
+as a secondary process. The re-acceleration of particles in the turbulent
+region immediately downstream of the shock should be efficient enough to impact
+particle spectra over several decades in energy. The so-called Alfv\'{e}nic
+drift and particle feedback on the shock structure are not required in this
+scenario. Additionally, we investigate whether synchrotron losses or
+magnetic-field damping play a more profound role in the formation of the
+non-thermal filaments. We solve the full particle transport equation in
+test-particle mode using hydrodynamic simulations of the SNR plasma flow. The
+background magnetic field is either computed from the induction equation or
+follows analytic profiles, depending on the model considered. Fast-mode waves
+in the downstream region provide the diffusion of particles in momentum space.
+We show that the broadband spectrum of Tycho can be well explained if
+magnetic-field damping and stochastic re-acceleration of particles are taken
+into account. Although not as efficient as standard DSA, stochastic
+acceleration leaves its imprint on the particle spectra, which is especially
+notable in the emission at radio wavelengths. We find a lower limit for the
+post-shock magnetic-field strength $\sim330\,\mathrm{\mu G}$, implying
+efficient amplification even for the magnetic-field damping scenario. For the
+formation of the filaments in the radio range magnetic-field damping is
+necessary, while the X-ray filaments are shaped by both the synchrotron losses
+and magnetic-field damping.",2006.04832v1
+2021-02-23,Influence of Ion-Neutral Damping on the Cosmic-Ray Streaming Instability: Magnetohydrodynamic Particle-in-cell Simulations,"We explore the physics of the gyro-resonant cosmic ray streaming instability
+(CRSI) including the effects of ion-neutral (IN) damping. This is the main
+damping mechanism in (partially-ionized) atomic and molecular gas, which are
+the primary components of the interstellar medium (ISM) by mass. Limitation of
+CRSI by IN damping is important in setting the amplitude of Alfv\'en waves that
+scatter cosmic rays and control galactic-scale transport. Our study employs the
+MHD-PIC hybrid fluid-kinetic numerical technique to follow linear growth as
+well as post-linear and saturation phases. During the linear phase of the
+instability -- where simulations and analytical theory are in good agreement --
+IN damping prevents wave growth at small and large wavelengths, with the
+unstable bandwidth lower for higher ion-neutral collision rate $\nu_{\rm in}$.
+Purely MHD effects during the post-linear phase extend the wave spectrum
+towards larger $k$. In the saturated state, the cosmic ray distribution evolves
+toward greater isotropy (lower streaming velocity) by scattering off of Alv\'en
+waves excited by the instability. In the absence of low-$k$ waves, CRs with
+sufficiently high momentum are not isotropized. The maximum wave amplitude and
+rate of isotropization of the distribution function decreases at higher
+$\nu_{\rm in}$. When the IN damping rate approaches the maximum growth rate of
+CSRI, wave growth and isotropization is suppressed. Implications of our results
+for CR transport in partially ionized ISM phases are discussed.",2102.11878v3
+2022-06-17,Quantum Dynamics of Magnetic Skyrmions: Consistent Path Integral Formulation,"We present a path integral formalism for the intrinsic quantum dynamics of
+magnetic skyrmions coupled to a thermal background of magnetic fluctuations.
+Upon promoting the skyrmion's collective coordinate $\boldsymbol{R}$ to a
+dynamic variable and integrating out the magnonic heat bath, we derive the
+generalized equation of motion for $\boldsymbol{R}$ with a non-local damping
+term that describes a steady-state skyrmion dynamics at finite temperatures.
+Being essentially temperature dependent, the intrinsic damping is shown to
+originate from the coupling of thermally activated magnon modes to the
+adiabatic potential driven by a rigid skyrmion motion, which can be regarded as
+another manifestation of emergent electrodynamics inherent to topological
+magnetic textures. We further argue that the diagonal components of the damping
+term act as the source of dissipation and inertia, while its off-diagonal
+components modify the gyrotropic motion of a magnetic skyrmion. By means of
+numerical calculations for the lattice spin model of chiral ferromagnets, we
+study the temperature behavior of the intrinsic damping as a function of
+magnetic field in periodic and confined geometries. The intrinsic damping is
+demonstrated to be highly non-local, revealing its quantum-mechanical nature,
+that becomes more pronounced with increasing temperature. At high temperatures
+when the magnon occupation factors are large, the intrinsic damping is shown to
+yield a modified Thiele's equation with the additional non-local dissipative
+and mass terms that exhibit an almost linear temperature behavior. Our results
+provide a microscopic background for semiclassical magnetization dynamics and
+establish a framework for understanding spin caloritronics effects in
+topological magnetic textures.",2206.08532v2
+2024-02-05,Revisiting the role of cosmic-ray driven Alfvén waves in pre-existing magnetohydrodynamic turbulence. I. Turbulent damping rates and feedback on background fluctuations,"Alfv\'en waves (AWs) excited by the cosmic-ray (CR) streaming instability
+(CRSI) are a fundamental ingredient for CR confinement. The effectiveness of
+self-confinement relies on a balance between CRSI growth rate and damping
+mechanisms acting on quasi-parallel AWs excited by CRs. One relevant mechanism
+is the so-called turbulent damping, in which an AW packet injected in
+pre-existing turbulence undergoes a cascade process due to its nonlinear
+interaction with fluctuations of the background. The turbulent damping of an AW
+packet in pre-existing magnetohydrodynamic turbulence is re-examined, revised,
+and extended to include most-recent theories of MHD turbulence that account for
+dynamic alignment and reconnection-mediated regime. The case in which the role
+of feedback of CR-driven AWs on pre-existing turbulence is important will also
+be discussed. Particular attention is given to the nonlinearity parameter
+$\chi^w$ that estimates the strength of nonlinear interaction between CR-driven
+AWs and background fluctuations. We point out the difference between $\chi^w$
+and $\chi^z$ that instead describes the strength of nonlinear interactions
+between pre-existing fluctuations. When $\chi^w$ is properly taken into
+account, one finds that (i) the turbulent damping rate of quasi-parallel AWs in
+anisotropic turbulence depends on the background-fluctuations' amplitude to the
+third power, hence is strongly suppressed, and (ii) the dependence on the AW's
+wavelength (and thus on the CR gyro-radius from which it is excited) is
+different from what has been previously obtained. Finally, (iii) when dynamic
+alignment of cascading fluctuations and the possibility of a
+reconnection-mediated range is included in the picture, the turbulent damping
+rate exhibits novel regimes and breaks. Finally, a criterion for CR-feedback is
+derived and simple phenomenological models of CR-modified turbulent scaling are
+provided.",2402.02901v1
+2006-10-24,Logical contradictions of Landau damping,"Landau damping/growing at boundary condition of excitation of a harmonic wave
+in collisionless ion-electron-neutrals plasma contradicts to the law of energy
+conservation of a wave damping/growing in space. There is also no criterion of
+a choice either damping or growing solution in difference from always
+non-damping in the direction of propagation Vlasov waves. Variety of other
+incongruities as consequence of Landau damping is specified also. Absence of
+explicit positivity and finiteness of wave solutions for electron distribution
+function near singularity point leads to need of imposing additional cutting
+off constraints with resulting positivity and finiteness of the electron
+distribution function at the singularity points and finiteness of the complex
+dispersion integral. Landau damping as a real physical phenomenon of
+collisionless damping does not exist. A relation is established for the real
+dispersion equation with real waves (see Appendices 2,4) between the averaged
+over period wave damping decrement and the collisional energy-exchange term of
+kinetic equation. Collisionless Vlasov-Landau damping is explained finally by
+the usual wrong use of nonlinearly complex wave functions leading to complex
+dispersion equation. All used solution of the complex dispersion equation for
+the simultaneously existing collisionless both exponentially damping and
+growing nonlinear complex waves is entirely, quantitatively and in its logical
+sense, different from the solution of initially real dispersion equation for
+real either damping or growing waves and should be discarded (see Appendices
+2,4,5,6). Collisionless damping is caused by unreasonable use of wave functions
+with complex frequency or complex wave number leading to complex dispersion
+relation with unphysical binomial virtual complex roots. Thus finding roots of
+the complex dispersion equation has only abstract mathematical interest.",0610220v67
+1999-12-17,Infrared Spectroscopy of a Massive Obscured Star Cluster in the Antennae Galaxies (NGC 4038/4039) with NIRSPEC,"We present infrared spectroscopy of the Antennae Galaxies (NGC 4038/4039)
+with NIRSPEC at the W. M. Keck Observatory. We imaged the star clusters in the
+vicinity of the southern nucleus (NGC 4039) in 0.39"" seeing in K-band using
+NIRSPEC's slit-viewing camera. The brightest star cluster revealed in the
+near-IR (M_K(0) = -17.9) is insignificant optically, but coincident with the
+highest surface brightness peak in the mid-IR (12-18 micron) ISO image
+presented by Mirabel et al. (1998). We obtained high signal-to-noise 2.03 -
+2.45 micron spectra of the nucleus and the obscured star cluster at R ~ 1900.
+  The cluster is very young (4 Myr old), massive (16e6 M_sun), and compact
+(density ~ 115 M_sun pc^(-3) within a 32 pc half-light radius), assuming a
+Salpeter IMF (0.1 - 100 M_sun). Its hot stars have a radiation field
+characterized by T_eff ~ 39,000 K, and they ionize a compact H II region with
+n_e ~ 1e4 cm^(-3). The stars are deeply embedded in gas and dust (A_V ~ 9-10
+mag), and their strong FUV field powers a clumpy photodissociation region with
+densities n_H >= 1e5 cm^(-3) on scales of up to 200 pc, radiating L[H_2 1-0
+S(1)] = 9600 L_sun.",9912369v1
+2000-09-07,Practical Quantum Cryptography: A Comprehensive Analysis (Part One),"We perform a comprehensive analysis of practical quantum cryptography (QC)
+systems implemented in actual physical environments via either free-space or
+fiber-optic cable quantum channels for ground-ground, ground-satellite,
+air-satellite and satellite-satellite links. (1) We obtain universal
+expressions for the effective secrecy capacity and rate for QC systems taking
+into account three important attacks on individual quantum bits, including
+explicit closed-form expressions for the requisite amount of privacy
+amplification. Our analysis also includes the explicit calculation in detail of
+the total cost in bits of continuous authentication, thereby obtaining new
+results for actual ciphers of finite length. (2) We perform for the first time
+a detailed, explicit analysis of all systems losses due to propagation, errors,
+noise, etc. as appropriate to both optical fiber cable- and satellite
+communications-based implementations of QC. (3) We calculate for the first time
+all system load costs associated to classical communication and computational
+constraints that are ancillary to, but essential for carrying out, the pure QC
+protocol itself. (4) We introduce an extended family of generalizations of the
+Bennett-Brassard (BB84) QC protocol that equally provide unconditional secrecy
+but allow for the possibility of optimizing throughput rates against specific
+cryptanalytic attacks. (5) We obtain universal predictions for maximal rates
+that can be achieved with practical system designs under realistic
+environmental conditions. (6) We propose a specific QC system design that
+includes the use of a novel method of high-speed photon detection that may be
+able to achieve very high throughput rates for actual implementations in
+realistic environments.",0009027v5
+2009-08-07,The Dominance of Metal-Rich Streams in Stellar Halos: A Comparison Between Substructure in M31 and Lambda-CDM Models,"Extensive photometric and spectroscopic surveys of the Andromeda galaxy (M31)
+have discovered tidal debris features throughout M31's stellar halo. We present
+stellar kinematics and metallicities in fields with identified substructure
+from our on-going SPLASH survey of M31 red giant branch stars with the DEIMOS
+spectrograph on the Keck II 10-m telescope. Radial velocity criteria are used
+to isolate members of the kinematically-cold substructures. The substructures
+are shown to be metal-rich relative to the rest of the dynamically hot stellar
+population in the fields in which they are found. We calculate the mean
+metallicity and average surface brightness of the various kinematical
+components in each field, and show that, on average, higher surface brightness
+features tend to be more metal-rich than lower surface brightness features.
+Simulations of stellar halo formation via accretion in a cosmological context
+are used to illustrate that the observed trend can be explained as a natural
+consequence of the observed dwarf galaxy mass-metallicity relation. A
+significant spread in metallicity at a given surface brightness is seen in the
+data; we show that this is due to time effects, namely the variation in the
+time since accretion of the tidal streams' progenitor onto the host halo. We
+show that in this theoretical framework a relationship between the
+alpha-enhancement and surface brightness of tidal streams is expected, which
+arises from the varying times of accretion of the progenitor satellites onto
+the host halo. Thus, measurements of the alpha-enrichment, metallicity, and
+surface brightness of tidal debris can be used to reconstruct the luminosity
+and time of accretion onto the host halo of the progenitors of tidal streams.",0908.1111v1
+2009-09-25,The SPLASH Survey: A Spectroscopic Portrait of Andromeda's Giant Southern Stream,"The giant southern stream (GSS) is the most prominent tidal debris feature in
+M31's stellar halo. The GSS is composed of a relatively metal-rich, high
+surface-brightness ""core"" and a lower metallicity, lower surface brightness
+""envelope."" We present Keck/DEIMOS spectroscopy of red giant stars in six
+fields in the vicinity of M31's GSS and one field on Stream C, an arc-like
+feature on M31's SE minor axis at R=60 kpc. Several GSS-related findings and
+measurements are presented here. We present the innermost kinematical detection
+of the GSS core to date (R=17 kpc). This field also contains the continuation
+of a second kinematically cold component originally seen in a GSS core field at
+R=21 kpc. The velocity gradients of the GSS and the second component in the
+combined data set are parallel over a radial range of 7 kpc, suggesting a
+possible bifurcation in the line-of-sight velocities of GSS stars. We also
+present the first kinematical detection of substructure in the GSS envelope.
+Using kinematically identified samples, we show that the envelope debris has a
+~0.7 dex lower mean photometric metallicity and possibly higher intrinsic
+velocity dispersion than the GSS core. The GSS is also identified in the field
+of the M31 dSph satellite And I; the GSS in this field has a metallicity
+distribution identical to that of the GSS core. We confirm the presence of two
+kinematically cold components in Stream C, and measure intrinsic velocity
+dispersions of ~10 and ~4 km/s. This compilation of the kinematical (mean
+velocity, intrinsic velocity dispersion) and chemical properties of stars in
+the GSS core and envelope, coupled with published surface brightness
+measurements and wide-area star-count maps, will improve constraints on the
+orbit and internal structure of the dwarf satellite progenitor.",0909.4540v1
+2011-05-28,Transmission Control of Two-User Slotted ALOHA Over Gilbert-Elliott Channel: Stability and Delay Analysis,"In this paper, we consider the problem of calculating the stability region
+and average delay of two user slotted ALOHA over a Gilbert-Elliott channel,
+where users have channel state information and adapt their transmission
+probabilities according to the channel state. Each channel has two states,
+namely, the 'good' and 'bad' states. In the 'bad' state, the channel is assumed
+to be in deep fade and the transmission fails with probability one, while in
+the 'good' state, there is some positive success probability. We calculate the
+Stability region with and without Multipacket Reception capability as well as
+the average delay without MPR. Our results show that the stability region of
+the controlled S-ALOHA is always a superset of the stability region of
+uncontrolled S-ALOHA. Moreover, if the channel tends to be in the 'bad' state
+for long proportion of time, then the stability region is a convex Polyhedron
+strictly containing the TDMA stability region and the optimal transmission
+strategy is to transmit with probability one whenever the nodes have packets
+and it is shown that this strategy is delay optimal. On the other hand, if the
+channel tends to be in the 'good' state more often, then the stability region
+is bounded by a convex curve and is strict subset of the TDMA stability region.
+We also show that enhancing the physical layer by allowing MPR capability can
+significantly enhance the performance while simplifying the MAC Layer design by
+the lack of the need of scheduling under some conditions. Furthermore, it is
+shown that transmission control not only allows handling higher stable arrival
+rates but also leads to lower delay for the same arrival rate compared with
+ordinary S-ALOHA.",1105.5676v2
+2012-10-11,Global Properties of M31's Stellar Halo from the SPLASH Survey. I. Surface Brightness Profile,"We present the surface brightness profile of M31's stellar halo out to a
+projected radius of 175 kpc. The surface brightness estimates are based on
+confirmed samples of M31 red giant branch stars derived from Keck/DEIMOS
+spectroscopic observations. A set of empirical spectroscopic and photometric
+M31 membership diagnostics is used to identify and reject foreground and
+background contaminants. This enables us to trace the stellar halo of M31 to
+larger projected distances and fainter surface brightnesses than previous
+photometric studies. The surface brightness profile of M31's halo follows a
+power-law with index -2.2 +/- 0.2 and extends to a projected distance of at
+least ~175 kpc (~ 2/3 of M31's virial radius), with no evidence of a downward
+break at large radii. The best-fit elliptical isophotes have b/a=0.94 with the
+major axis of the halo aligned along the minor axis of M31's disk, consistent
+with a prolate halo, although the data are also consistent with M31's halo
+having spherical symmetry. The fact that tidal debris features are
+kinematically cold is used to identify substructure in the spectroscopic fields
+out to projected radii of 90 kpc, and investigate the effect of this
+substructure on the surface brightness profile. The scatter in the surface
+brightness profile is reduced when kinematically identified tidal debris
+features in M31 are statistically subtracted; the remaining profile indicates a
+comparatively diffuse stellar component to M31's stellar halo exists to large
+distances. Beyond 90 kpc, kinematically cold tidal debris features can not be
+identified due to small number statistics; nevertheless, the significant
+field-to-field variation in surface brightness beyond 90 kpc suggests that the
+outermost region of M31's halo is also comprised to a significant degree of
+stars stripped from accreted objects.",1210.3362v2
+2014-09-12,Global Properties of M31's Stellar Halo from the SPLASH Survey: II. Metallicity Profile,"We present the metallicity distribution of red giant branch (RGB) stars in
+M31's stellar halo, derived from photometric metallicity estimates for over
+1500 spectroscopically confirmed RGB halo stars. The stellar sample comes from
+38 halo fields observed with the Keck/DEIMOS spectrograph, ranging from 9 to
+175 kpc in projected distance from M31's center, and includes 52 confirmed M31
+halo stars beyond 100 kpc. While a wide range of metallicities is seen
+throughout the halo, the metal-rich peak of the metallicity distribution
+function becomes significantly less prominent with increasing radius. The
+metallicity profile of M31's stellar halo shows a continuous gradient from 9 to
+~100 kpc, with a magnitude of -0.01 dex/kpc. The stellar velocity distributions
+in each field are used to identify stars that are likely associated with tidal
+debris features. The removal of tidal debris features does not significantly
+alter the metallicity gradient in M31's halo: a gradient is maintained in
+fields spanning 10 to 90 kpc. We analyze the halo metallicity profile, as well
+as the relative metallicities of stars associated with tidal debris features
+and the underlying halo population, in the context of current simulations of
+stellar halo formation. We argue that the large scale gradient in M31's halo
+implies M31 accreted at least one relatively massive progenitor in the past,
+while the field to field variation seen in the metallicity profile indicates
+that multiple smaller progenitors are likely to have contributed substantially
+to M31's outer halo.",1409.3843v1
+2016-07-15,Solving the stochastic Landau-Lifshitz-Gilbert-Slonczewski equation for monodomain nanomagnets : A survey and analysis of numerical techniques,"The stochastic Landau-Lifshitz-Gilbert-Slonczewski (s-LLGS) equation is
+widely used to study the temporal evolution of the macrospin subject to spin
+torque and thermal noise. The numerical simulation of the s-LLGS equation
+requires an appropriate choice of stochastic calculus and numerical integration
+scheme. In this paper, we comprehensively evaluate the accuracy and complexity
+of various numerical techniques to solve the s-LLGS equation. We focus on
+implicit midpoint, Heun, and Euler-Heun methods that converge to the
+Stratonovich solution of the s-LLGS equation. By performing numerical tests for
+both strong (path-wise) and weak (statistical) convergence, we quantify the
+accuracy of various numerical schemes used to solve the s-LLGS equation. We
+demonstrate a new method intended to solve Stochastic Differential Equations
+(SDEs) with small noise (RK4-Heun), and test its capability to handle the
+s-LLGS equation. We also discuss the circuit implementation of nanomagnets for
+large-scale SPICE-based simulations. We evaluate the efficacy of SPICE in
+handling the stochastic dynamics of the multiplicative noise in the s-LLGS
+equation. Numerical schemes such as Euler and Gear, typically used by
+SPICE-based circuit simulators do not yield the expected outcome when solving
+the Stratonovich s-LLGS equation. While the trapezoidal method in SPICE does
+solve for the Stratonovich solution, its accuracy is limited by the minimum
+time step of integration in SPICE. We implement the s-LLGS equation in both its
+cartesian and spherical coordinates form in SPICE and compare the stability and
+accuracy of the two implementations. The results in this paper will serve as
+guidelines for researchers to understand the tradeoffs between accuracy and
+complexity of various numerical methods and the choice of appropriate calculus
+to solve the s-LLGS equation.",1607.04596v4
+2016-11-30,Low Energy Supergravity Revisited (I),"General forms of the K\""ahler and superpotenials that lead to consistent low
+energy broken Supersymmetry originating from $N=1$ Supergravity have been
+classified and used for model building since more than three decades. We point
+out the incompleteness of this classification when hidden sector vacuum
+expectation values are of the order of the Planck mass. Focusing in this paper
+mainly on the case of minimal K\""ahler potential, we adopt a rigorous approach
+that retrieves on the one hand the known forms, and demonstrate on the other
+hand the existence of a whole set of new forms for the superpotential of which
+we give a complete classification. The latter forms involve a new type of
+chiral superfields having the unusual property of belonging neither to the
+hidden sector nor to the conventional observable sector. Comparing the obtained
+forms with the conventional ones, we argue how new possibilities for model
+building can arise, and discuss the gravity mediation of soft as well as
+additional hard (but parametrically small) Supersymmetry breaking, in the
+presence of the new type of chiral superfields. In the simplest case, we study
+the vacuum structure, characterize the masses and couplings of the scalar
+components to the hidden and observable sectors and discuss briefly the
+physical role they could play. In the generic case, we estimate the magnitude
+and possible consequences of the hard breaking of Supersymmetry in terms of the
+interplay between hidden and visible sectors mass scales.",1611.10327v2
+2018-09-24,Ionic Tuning of Cobaltites at the Nanoscale,"Control of materials through custom design of ionic distributions represents
+a powerful new approach to develop future technologies ranging from spintronic
+logic and memory devices to energy storage. Perovskites have shown particular
+promise for ionic devices due to their high ion mobility and sensitivity to
+chemical stoichiometry. In this work, we demonstrate a solid-state approach to
+control of ionic distributions in (La,Sr)CoO$_{3}$ thin films. Depositing a Gd
+capping layer on the perovskite film, oxygen is controllably extracted from the
+structure, up-to 0.5 O/u.c. throughout the entire 36 nm thickness. Commensurate
+with the oxygen extraction, the Co valence state and saturation magnetization
+show a smooth continuous variation. In contrast, magnetoresistance measurements
+show no-change in the magnetic anisotropy and a rapid increase in the
+resistivity over the same range of oxygen stoichiometry. These results suggest
+significant phase separation, with metallic ferromagnetic regions and
+oxygen-deficient, insulating, non-ferromagnetic regions, forming percolated
+networks. Indeed, X-ray diffraction identifies oxygen-vacancy ordering,
+including transformation to a brownmillerite crystal structure. The unexpected
+transformation to the brownmillerite phase at ambient temperature is further
+confirmed by high-resolution scanning transmission electron microscopy which
+shows significant structural - and correspondingly chemical - phase separation.
+This work demonstrates room-temperature ionic control of magnetism, electrical
+resistivity, and crystalline structure in a 36 nm thick film, presenting new
+opportunities for ionic devices that leverage multiple material
+functionalities.",1809.08728v1
+2019-04-10,The Convergence of Iterative Delegations in Liquid Democracy in a Social Network,"Liquid democracy is a collective decision making paradigm which lies between
+direct and representative democracy. One of its main features is that voters
+can delegate their votes in a transitive manner such that: A delegates to B and
+B delegates to C leads to A indirectly delegates to C. These delegations can be
+effectively empowered by implementing liquid democracy in a social network, so
+that voters can delegate their votes to any of their neighbors in the network.
+However, it is uncertain that such a delegation process will lead to a stable
+state where all voters are satisfied with the people representing them. We
+study the stability (w.r.t. voters preferences) of the delegation process in
+liquid democracy and model it as a game in which the players are the voters and
+the strategies are their possible delegations. We answer several questions on
+the equilibria of this process in any social network or in social networks that
+correspond to restricted types of graphs.
+  We show that a Nash-equilibrium may not exist, and that it is even
+NP-complete to decide whether one exists or not. This holds even if the social
+network is a complete graph or a bounded degree graph. We further show that
+this existence problem is W[1]-hard w.r.t. the treewidth of the social network.
+Besides these hardness results, we demonstrate that an equilibrium always
+exists whatever the preferences of the voters iff the social network is a tree.
+We design a dynamic programming procedure to determine some desirable
+equilibria (e.g., minimizing the dissatisfaction of the voters) in polynomial
+time for tree social networks. Lastly, we study the convergence of delegation
+dynamics. Unfortunately, when an equilibrium exists, we show that a best
+response dynamics may not converge, even if the social network is a path or a
+complete graph.",1904.05775v2
+2019-06-20,Ongoing Vaccine and Monoclonal Antibody HIV Prevention Efficacy Trials and Considerations for Sequel Efficacy Trial Designs,"Four randomized placebo-controlled efficacy trials of a candidate vaccine or
+passively infused monoclonal antibody for prevention of HIV-1 infection are
+underway (HVTN 702 in South African men and women; HVTN 705 in sub-Saharan
+African women; HVTN 703/HPTN 081 in sub-Saharan African women; HVTN 704/HPTN
+085 in U.S., Peruvian, Brazilian, and Swiss men or transgender persons who have
+sex with men). Several challenges are posed to the optimal design of the sequel
+efficacy trials, including: (1) how to account for the evolving mosaic of
+effective prevention interventions that may be part of the trial design or
+standard of prevention; (2) how to define viable and optimal sequel trial
+designs depending on the primary efficacy results and secondary 'correlates of
+protection' results of each of the ongoing trials; and (3) how to define the
+primary objective of sequel efficacy trials if HIV-1 incidence is expected to
+be very low in all study arms such that a standard trial design has a steep
+opportunity cost. After summarizing the ongoing trials, I discuss statistical
+science considerations for sequel efficacy trial designs, both generally and
+specifically to each trial listed above. One conclusion is that the results of
+'correlates of protection' analyses, which ascertain how different host
+immunological markers and HIV-1 viral features impact HIV-1 risk and prevention
+efficacy, have an important influence on sequel trial design. This influence is
+especially relevant for the monoclonal antibody trials because of the focused
+pre-trial hypothesis that potency and coverage of serum neutralization
+constitutes a surrogate endpoint for HIV-1 infection... (see manuscript for the
+full abstract)",1906.08409v1
+2019-08-12,Elemental Abundances in M31: First Alpha and Iron Abundance Measurements in M31's Giant Stellar Stream,"We present the first measurements of [Fe/H] and [$\alpha$/Fe] abundances,
+obtained using spectral synthesis modeling, for red giant branch stars in M31's
+giant stellar stream. The spectroscopic observations, obtained at a projected
+distance of 17 kpc from M31's center, yielded 61 stars with [Fe/H]
+measurements, including 21 stars with [$\alpha$/Fe] measurements, from 112
+targets identified as M31 stars. The [Fe/H] measurements confirm the
+expectation from photometric metallicity estimates that stars in this region of
+M31's halo are relatively metal-rich compared to stars in the MW's inner halo:
+more than half the stars in the field, including those not associated with
+kinematically identified substructure, have [Fe/H] abundances $> -1.0$. The
+stars in this field are $\alpha$-enhanced at lower metallicities, while
+[$\alpha$/Fe] decreases with increasing [Fe/H] above metallicities of [Fe/H]
+$\gtrsim -0.9$. Three kinematical components have been previously identified in
+this field: the giant stellar stream, a second kinematically cold feature of
+unknown origin, and M31's kinematically hot halo. We compare probabilistic
+[Fe/H] and [$\alpha$/Fe] distribution functions for each of the components. The
+giant stellar stream and the second kinematically cold feature have very
+similar abundance distributions, while the halo component is more metal-poor.
+Although the current sample sizes are small, a comparison of the abundances of
+stars in the giant stellar stream field with abundances of M31 halo and dSph
+stars from the literature indicate that the progenitor of the stream was likely
+more massive, and experienced a higher efficiency of star formation, than M31's
+existing dSphs or the dEs NGC147 and NGC185.",1908.04429v1
+2019-08-21,Generalized Metric Repair on Graphs,"Many modern data analysis algorithms either assume or are considerably more
+efficient if the distances between the data points satisfy a metric. These
+algorithms include metric learning, clustering, and dimension reduction. As
+real data sets are noisy, distances often fail to satisfy a metric. For this
+reason, Gilbert and Jain and Fan et al. introduced the closely related sparse
+metric repair and metric violation distance problems. The goal of these
+problems is to repair as few distances as possible to ensure they satisfy a
+metric. Three variants were considered, one admitting a polynomial time
+algorithm. The other variants were shown to be APX-hard, and an
+$O(OPT^{1/3})$-approximation was given, where $OPT$ is the optimal solution
+size.
+  In this paper, we generalize these problems to no longer consider all
+distances between the data points. That is, we consider a weighted graph $G$
+with corrupted weights $w$, and our goal is to find the smallest number of
+weight modifications so that the resulting weighted graph distances satisfy a
+metric. This is a natural generalization and is more flexible as it takes into
+account different relationships among the data points. As in previous work, we
+distinguish among the types of repairs permitted and focus on the increase only
+and general versions. We demonstrate the inherent combinatorial structure of
+the problem, and give an approximation-preserving reduction from MULTICUT.
+Conversely, we show that for any fixed constant $\varsigma$, for the large
+class of $\varsigma$-chordal graphs, the problems are fixed parameter
+tractable. Call a cycle broken if it contains an edge whose weight is larger
+than the sum of all its other edges, and call the amount of this difference its
+deficit. We present approximation algorithms, one which depends on the maximum
+number of edges in a broken cycle, and one which depends on the number of
+distinct deficit values.",1908.08411v1
+2019-09-19,Parameterized Complexity of Manipulating Sequential Allocation,"The sequential allocation protocol is a simple and popular mechanism to
+allocate indivisible goods, in which the agents take turns to pick the items
+according to a predefined sequence. While this protocol is not strategy-proof,
+it has been shown recently that finding a successful manipulation for an agent
+is an NP-hard problem (Aziz et al., 2017). Conversely, it is also known that
+finding an optimal manipulation can be solved in polynomial time in a few
+cases: if there are only two agents or if the manipulator has a binary or a
+lexicographic utility function. In this work, we take a parameterized approach
+to provide several new complexity results on this manipulation problem. More
+precisely, we give a complete picture of its parameterized complexity w.r.t.
+the following three parameters: the number $n$ of agents, the number $\mu(a_1)$
+of times the manipulator $a_1$ picks in the picking sequence, and the maximum
+range $\mathtt{rg}^{\max}$ of an item. This third parameter is a correlation
+measure on the preference rankings of the agents. In particular, we show that
+the problem of finding an optimal manipulation can be solved in polynomial time
+if $n$ or $\mu(a_1)$ is a constant, and that it is fixed-parameter tractable
+w.r.t. $\mathtt{rg}^{\max}$ and $n+\mu(a_1)$. Interestingly enough, we show
+that w.r.t. the single parameters $n$ and $\mu(a_1)$ it is W[1]-hard. Moreover,
+we provide an integer program and a dynamic programming scheme to solve the
+manipulation problem and we show that a single manipulator can increase the
+utility of her bundle by a multiplicative factor which is at most 2.",1909.08920v4
+2019-11-06,Doppler Spectrum Classification with CNNs via Heatmap Location Encoding and a Multi-head Output Layer,"Spectral Doppler measurements are an important part of the standard
+echocardiographic examination. These measurements give important insight into
+myocardial motion and blood flow providing clinicians with parameters for
+diagnostic decision making. Many of these measurements can currently be
+performed automatically with high accuracy, increasing the efficiency of the
+diagnostic pipeline. However, full automation is not yet available because the
+user must manually select which measurement should be performed on each image.
+In this work we develop a convolutional neural network (CNN) to automatically
+classify cardiac Doppler spectra into measurement classes. We show how the
+multi-modal information in each spectral Doppler recording can be combined
+using a meta parameter post-processing mapping scheme and heatmaps to encode
+coordinate locations. Additionally, we experiment with several state-of-the-art
+network architectures to examine the tradeoff between accuracy and memory usage
+for resource-constrained environments. Finally, we propose a confidence metric
+using the values in the last fully connected layer of the network. We analyze
+example images that fall outside of our proposed classes to show our confidence
+metric can prevent many misclassifications. Our algorithm achieves 96% accuracy
+on a test set drawn from a separate clinical site, indicating that the proposed
+method is suitable for clinical adoption and enabling a fully automatic
+pipeline from acquisition to Doppler spectrum measurements.",1911.02407v2
+2020-01-02,"The Effect of Treatment-Related Deaths and ""Sticky"" Diagnoses on Recorded Prostate Cancer Mortality","Background: Although recorded cancer mortality should include both deaths
+from cancer and deaths from cancer treatment, there is evidence suggesting that
+the measure may be incomplete. To investigate the completeness of recorded
+prostate cancer mortality, we compared other-cause (non-prostate cancer)
+mortality in men found and not found to have prostate cancer following a needle
+biopsy.
+  Methods: We linked Medicare claims data to SEER data to analyze survival in
+the population of men aged 65+ enrolled in Medicare who resided in a SEER area
+and received a needle biopsy in 1993-2001. We compared other-cause mortality in
+men found to have prostate cancer (n=53,462) to that in men not found to have
+prostate cancer (n=103,659).
+  Results: The age-race adjusted other-cause mortality rate was 471 per 10,000
+person-years in men found to have prostate cancer vs. 468 per 10,000 in men not
+found to have prostate cancer (RR = 1.01;95% CI:0.98-1.03). The effect was
+modified, however, by age. The RR declined in a stepwise fashion from 1.08 (95%
+CI:1.03-1.14) in men age 65-69 to 0.89 (95% CI:0.83-0.95) in men age 85 and
+older. If the excess (or deficit) in other-cause mortality were added to the
+recorded prostate cancer mortality, prostate cancer mortality would rise 23% in
+the youngest age group (from 90 to 111 per 10,000) and would fall 30% in the
+oldest age group (from 551 to 388 per 10,000).
+  Conclusion: Although recorded prostate cancer mortality appears to be an
+accurate measure overall, it systematically underestimates the mortality
+associated with prostate cancer diagnosis and treatment in younger men and
+overestimates it in the very old. We surmise that in younger men
+treatment-related deaths are incompletely captured in recorded prostate cancer
+mortality, while in older men the diagnosis ""sticks""-- once diagnosed, they are
+more likely to be said to have died from the disease.",2001.00492v1
+2020-06-09,Elemental Abundances in M31: Iron and Alpha Element Abundances in M31's Outer Halo,"We present [Fe/H] and [$\alpha$/Fe] abundances, derived using spectral
+synthesis techniques, for stars in M31's outer stellar halo. The 21 [Fe/H]
+measurements and 7 [$\alpha$/Fe] measurements are drawn from fields ranging
+from 43 to 165 kpc in projected distance from M31. We combine our measurements
+with existing literature measurements, and compare the resulting sample of 23
+stars with [Fe/H] and 9 stars with [$\alpha$/Fe] measurements in M31's outer
+halo with [$\alpha$/Fe] and [Fe/H] measurements, also derived from spectral
+synthesis, in M31's inner stellar halo ($r < $26 kpc) and dSph galaxies. The
+stars in M31's outer halo have [$\alpha$/Fe] patterns that are consistent with
+the largest of M31's dSph satellites (And I and And VII). These abundances
+provide tentative evidence that the [$\alpha$/Fe] abundances of stars in M31's
+outer halo are more similar to the abundances of Milky Way halo stars than to
+the abundances of stars in M31's inner halo. We also compare the spectral
+synthesis-based [Fe/H] measurements of stars in M31's halo with previous
+photometric [Fe/H] estimates, as a function of projected distance from M31. The
+spectral synthesis-based [Fe/H] measurements are consistent with a large-scale
+metallicity gradient previously observed in M31's stellar halo to projected
+distances as large as 100 kpc.",2006.05430v1
+2020-11-11,Unique Decoding of Explicit $ε$-balanced Codes Near the Gilbert-Varshamov Bound,"The Gilbert-Varshamov bound (non-constructively) establishes the existence of
+binary codes of distance $1/2 -\epsilon$ and rate $\Omega(\epsilon^2)$ (where
+an upper bound of $O(\epsilon^2\log(1/\epsilon))$ is known). Ta-Shma [STOC
+2017] gave an explicit construction of $\epsilon$-balanced binary codes, where
+any two distinct codewords are at a distance between $1/2 -\epsilon/2$ and
+$1/2+\epsilon/2$, achieving a near optimal rate of
+$\Omega(\epsilon^{2+\beta})$, where $\beta \to 0$ as $\epsilon \to 0$.
+  We develop unique and list decoding algorithms for (essentially) the family
+of codes constructed by Ta-Shma. We prove the following results for
+$\epsilon$-balanced codes with block length $N$ and rate
+$\Omega(\epsilon^{2+\beta})$ in this family:
+  - For all $\epsilon, \beta > 0$ there are explicit codes which can be
+uniquely decoded up to an error of half the minimum distance in time
+$N^{O_{\epsilon, \beta}(1)}$.
+  - For any fixed constant $\beta$ independent of $\epsilon$, there is an
+explicit construction of codes which can be uniquely decoded up to an error of
+half the minimum distance in time $(\log(1/\epsilon))^{O(1)} \cdot
+N^{O_\beta(1)}$.
+  - For any $\epsilon > 0$, there are explicit $\epsilon$-balanced codes with
+rate $\Omega(\epsilon^{2+\beta})$ which can be list decoded up to error $1/2 -
+\epsilon'$ in time $N^{O_{\epsilon,\epsilon',\beta}(1)}$, where $\epsilon',
+\beta \to 0$ as $\epsilon \to 0$.
+  The starting point of our algorithms is the list decoding framework from Alev
+et al. [SODA 2020], which uses the Sum-of-Squares SDP hierarchy. The rates
+obtained there were quasipolynomial in $\epsilon$. Here, we show how to
+overcome the far from optimal rates of this framework obtaining unique decoding
+algorithms for explicit binary codes of near optimal rate. These codes are
+based on simple modifications of Ta-Shma's construction.",2011.05500v1
+2021-03-30,Equivalence between Sobolev spaces of first-order dominating mixed smoothness and unanchored ANOVA spaces on $\mathbb{R}^d$,"We prove that a variant of the classical Sobolev space of first-order
+dominating mixed smoothness is equivalent (under a certain condition) to the
+unanchored ANOVA space on $\mathbb{R}^d$, for $d \geq 1$. Both spaces are
+Hilbert spaces involving weight functions, which determine the behaviour as
+different variables tend to $\pm \infty$, and weight parameters, which
+represent the influence of different subsets of variables. The unanchored ANOVA
+space on $\mathbb{R}^d$ was initially introduced by Nichols & Kuo in 2014 to
+analyse the error of quasi-Monte Carlo (QMC) approximations for integrals on
+unbounded domains; whereas the classical Sobolev space of dominating mixed
+smoothness was used as the setting in a series of papers by Griebel, Kuo &
+Sloan on the smoothing effect of integration, in an effort to develop a
+rigorous theory on why QMC methods work so well for certain non-smooth
+integrands with kinks or jumps coming from option pricing problems. In this
+same setting, Griewank, Kuo, Le\""ovey & Sloan in 2018 subsequently extended
+these ideas by developing a practical smoothing by preintegration technique to
+approximate integrals of such functions with kinks or jumps.
+  We first prove the equivalence in one dimension (itself a non-trivial task),
+before following a similar, but more complicated, strategy to prove the
+equivalence for general dimensions. As a consequence of this equivalence, we
+analyse applying QMC combined with a preintegration step to approximate the
+fair price of an Asian option, and prove that the error of such an
+approximation using $N$ points converges at a rate close to $1/N$.",2103.16075v3
+2021-06-13,Advantages of a semi-implicit scheme over a fully implicit scheme for Landau-Lifshitz-Gilbert equation,"Magnetization dynamics in magnetic materials is modeled by the
+Landau-Lifshitz-Gilbert (LLG) equation. In the LLG equation, the length of
+magnetization is conserved and the system energy is dissipative. Implicit and
+semi-implicit schemes have been used in micromagnetics simulations due to their
+unconditional numerical stability. In more details, implicit schemes preserve
+the properties of the LLG equation, but solve a nonlinear system of equations
+per time step. In contrast, semi-implicit schemes only solve a linear system of
+equations, while additional operations are needed to preserve the length of
+magnetization. It still remains unclear which one shall be used if both
+implicit and semi-implicit schemes are available. In this work, using the
+implicit Crank-Nicolson (ICN) scheme as a benchmark, we propose to make this
+implicit scheme semi-implicit. It can be proved that both schemes are
+second-order accurate in space and time. For the unique solvability of
+nonlinear systems of equations in the ICN scheme, we require that the temporal
+step size scales quadratically with the spatial mesh size. It is numerically
+verified that the convergence of the nonlinear solver becomes slower for larger
+temporal step size and multiple magnetization profiles are obtained for
+different initial guesses. The linear systems of equations in the semi-implicit
+CN (SICN) scheme are unconditionally uniquely solvable, and the condition that
+the temporal step size scales linearly with the spatial mesh size is needed in
+the convergence of the SICN scheme. In terms of numerical efficiency, the SICN
+scheme achieves the same accuracy as the ICN scheme with less computational
+time. Based on these results, we conclude that a semi-implicit scheme is
+superior to its implicit analog both theoretically and numerically, and we
+recommend the semi-implicit scheme in micromagnetics simulations if both
+methods are available.",2106.06936v1
+2021-08-06,A second-order semi-implicit method for the inertial Landau-Lifshitz-Gilbert equation,"Recent theoretical and experimental advances show that the inertia of
+magnetization emerges at sub-picoseconds and contributes to the ultrafast
+magnetization dynamics which cannot be captured intrinsically by the LLG
+equation. Therefore, as a generalization, the inertial Landau-Lifshitz-Gilbert
+(iLLG) equation is proposed to model the ultrafast magnetization dynamics.
+Mathematically, the LLG equation is a nonlinear system of parabolic type with
+(possible) degeneracy. However, the iLLG equation is a nonlinear system of
+mixed hyperbolic-parabolic type with degeneracy, and exhibits more complicated
+structures. It behaves like a hyperbolic system at the sub-picosecond scale
+while behaves like a parabolic system at larger timescales. Such hybrid
+behaviors impose additional difficulties on designing numerical methods for the
+iLLG equation. In this work, we propose a second-order semi-implicit scheme to
+solve the iLLG equation. The second temporal derivative of magnetization is
+approximated by the standard centered difference scheme and the first
+derivative is approximated by the midpoint scheme involving three time steps.
+The nonlinear terms are treated semi-implicitly using one-sided interpolation
+with the second-order accuracy. At each step, the unconditionally unique
+solvability of the unsymmetric linear system of equations in the proposed
+method is proved with a detailed discussion on the condition number.
+Numerically, the second-order accuracy in both time and space is verified.
+Using the proposed method, the inertial effect of ferromagnetics is observed in
+micromagnetics simulations at small timescales, in consistency with the
+hyperbolic property of the model at sub-picoseconds. For long time simulations,
+the results of the iLLG model are in nice agreements with those of the LLG
+model, in consistency with the parabolic feature of the iLLG model at larger
+timescales.",2108.03060v1
+2021-09-08,"Flares, Rotation, and Planets of the AU Mic System from TESS Observations","AU Mic is a young ($\sim$24 Myr), pre-Main Sequence M~dwarf star that was
+observed in the first month of science observations of the Transiting Exoplanet
+Survey Satellite (TESS) and re-observed two years later. This target has
+photometric variability from a variety of sources that is readily apparent in
+the TESS light curves; spots induce modulation in the light curve, flares are
+present throughout (manifesting as sharp rises with slow exponential decay
+phases), and transits of AU Mic b may be seen by eye as dips in the light
+curve. We present a combined analysis of both TESS Sector 1 and Sector 27 AU
+Mic light curves including the new 20-second cadence data from TESS Year 3. We
+compare flare rates between both observations and analyze the spot evolution,
+showing that the activity levels increase slightly from Sector 1 to Sector 27.
+Furthermore, the 20-second data collection allows us to detect more flares,
+smaller flares, and better resolve flare morphology in white light as compared
+to the 2-minute data collection mode. We also refine the parameters for AU Mic
+b by fitting three additional transits of AU Mic b from Sector 27 using a model
+that includes stellar activity. We show that the transits exhibit clear transit
+timing variations (TTVs) with an amplitude of $\sim$80 seconds. We also detect
+three transits of a 2.8 $R_\oplus$ planet, AU Mic c, which has a period of
+18.86 days.",2109.03924v1
+2021-10-29,The TREX Survey: Kinematical Complexity Throughout M33's Stellar Disk and Evidence for a Stellar Halo,"We present initial results from a large spectroscopic survey of stars
+throughout M33's stellar disk. We analyze a sample of 1667 red giant branch
+(RGB) stars extending to projected distances of $\sim 11$ kpc from M33's center
+($\sim 18$ kpc, or $\sim 10$ scale lengths, in the plane of the disk). The
+line-of-sight velocities of RGB stars show the presence of two kinematical
+components. One component is consistent with rotation in the plane of M33's HI
+disk and has a velocity dispersion ($\sim 19$ km s$^{-1}$) consistent with that
+observed in a comparison sample of younger stars, while the second component
+has a significantly higher velocity dispersion. A two-component fit to the RGB
+velocity distribution finds that the high dispersion component has a velocity
+dispersion of $59.3^{+2.6}_{-2.5}$ km s$^{-1}$ and rotates very slowly in the
+plane of the disk (consistent with no rotation at the $<1.5\sigma$ level),
+which favors interpreting it as a stellar halo rather than a thick disk
+population. A spatial analysis indicates that the fraction of RGB stars in the
+high-velocity-dispersion component decreases with increasing radius over the
+range covered by the spectroscopic sample. Our spectroscopic sample establishes
+that a significant high-velocity-dispersion component is present in M33's RGB
+population from near M33's center to at least the radius where M33's HI disk
+begins to warp at 30$'$ ($\sim 7.5$ kpc) in the plane of the disk. This is the
+first detection and spatial characterization of a kinematically hot stellar
+component throughout M33's inner regions.",2110.15773v1
+2021-11-23,Magnetism in Metastable and Annealed Compositionally Complex Alloys,"Compositionally complex materials (CCMs) present a potential paradigm shift
+in the design of magnetic materials. These alloys exhibit long-range structural
+order coupled with limited or no chemical order. As a result, extreme local
+environments exist with a large opposing magnetic energy term, which can
+manifest large changes in the magnetic behavior. In the current work, the
+magnetic properties of (Cr, Mn, Fe, Ni) alloys are presented. These materials
+were prepared by room-temperature combinatorial sputtering, resulting in a
+range of compositions with a single BCC structural phase and no chemical
+ordering. The combinatorial growth technique allows CCMs to be prepared outside
+of their thermodynamically stable phase, enabling the exploration of otherwise
+inaccessible order. The mixed ferromagnetic and antiferromagnetic interactions
+in these alloys causes frustrated magnetic behavior, which results in an
+extremely low coercivity (<1 mT), which increases rapidly at 50 K. At low
+temperatures, the coercivity achieves values of nearly 500 mT, which is
+comparable to some high-anisotropy magnetic materials. Commensurate with the
+divergent coercivity is an atypical drop in the temperature dependent
+magnetization. These effects are explained by a mixed magnetic phase model,
+consisting of ferro-, antiferro , and frustrated magnetic regions, and are
+rationalized by simulations. A machine-learning algorithm is employed to
+visualize the parameter space and inform the development of subsequent
+compositions. Annealing the samples at 600 {\deg}C orders the sample, more-than
+doubling the Curie temperature and increasing the saturation magnetization by
+as much as 5x. Simultaneously, the large coercivities are suppressed, resulting
+in magnetic behavior that is largely temperature independent over a range of
+350 K.",2111.12188v1
+2021-11-23,Controlling magnetic configuration in soft-hard bilayers probed by polarized neutron reflectometry,"Hard/soft magnetic bilayer thin films have been widely used in data storage
+technologies and permanent magnet applications. The magnetic configuration and
+response to temperatures and magnetic fields in these heterostructures are
+considered to be highly dependent on the interfacial coupling. However, the
+intrinsic properties of each of the layers, such as the saturation
+magnetization and layer thickness, also strongly influence the magnetic
+configuration. Changing these parameters provides an effective method to tailor
+magnetic properties in composite magnets. Here, we use polarized neutron
+reflectometry (PNR) to experimentally probe the interfacial magnetic
+configurations in hard/soft bilayer thin films: L10-FePt/A1-FePt, [Co/Pd]
+/CoPd, [Co/Pt] /FeNi and L10-FePt/Fe, which all have a perpendicular magnetic
+anisotropy in the hard layer. These films were designed with different soft and
+hard layer thicknesses (t_soft and t_hard) and saturation magnetization
+(M_s^soft and M_s^hard), respectively. The influences of an in-plane magnetic
+field (H_ip) and temperature (T) are also studied using a L10 FePt/A1-FePt
+bilayer sample. Comparing the PNR results to micromagnetic simulations reveals
+that the interfacial magnetic configuration is highly dependent on t_soft,
+M_s^soft and the external factors (H_ip and T), and has a relatively weak
+dependence on t_hard and M_s^hard. Key among these results, for thin t_soft,
+the hard and soft layers are rigidly coupled in the out-of-plane direction,
+then undergo a transition to relax in-plane. This transition can be delayed to
+larger t_soft by decreasing M_s^soft. Understanding the influence of these
+parameters on the magnetic configuration is critical to designing functional
+composite magnets for applications.",2111.12191v1
+2022-01-18,On-demand electrical control of spin qubits,"Once called a ""classically non-describable two-valuedness"" by Pauli , the
+electron spin is a natural resource for long-lived quantum information since it
+is mostly impervious to electric fluctuations and can be replicated in large
+arrays using silicon quantum dots, which offer high-fidelity control.
+Paradoxically, one of the most convenient control strategies is the integration
+of nanoscale magnets to artificially enhance the coupling between spins and
+electric field, which in turn hampers the spin's noise immunity and adds
+architectural complexity. Here we demonstrate a technique that enables a
+\emph{switchable} interaction between spins and orbital motion of electrons in
+silicon quantum dots, without the presence of a micromagnet. The naturally weak
+effects of the relativistic spin-orbit interaction in silicon are enhanced by
+more than three orders of magnitude by controlling the energy quantisation of
+electrons in the nanostructure, enhancing the orbital motion. Fast electrical
+control is demonstrated in multiple devices and electronic configurations,
+highlighting the utility of the technique. Using the electrical drive we
+achieve coherence time $T_{2,{\rm Hahn}}\approx50 \mu$s, fast single-qubit
+gates with ${T_{\pi/2}=3}$ ns and gate fidelities of 99.93 % probed by
+randomised benchmarking. The higher gate speeds and better compatibility with
+CMOS manufacturing enabled by on-demand electric control improve the prospects
+for realising scalable silicon quantum processors.",2201.06679v2
+2022-04-28,Anti-microbial properties of a multi-component alloy,"High traffic touch surfaces such as doorknobs, countertops, and handrails can
+be transmission points for the spread of pathogens, emphasizing the need to
+develop materials that actively self-sanitize. Metals are frequently used for
+these surfaces due to their durability, but many metals also possess
+antimicrobial properties which function through a variety of mechanisms. This
+work investigates metallic alloys comprised of several bioactive metals with
+the target of achieving broad-spectrum, rapid bioactivity through synergistic
+activity. An entropy-motivated stabilization paradigm is proposed to prepare
+scalable alloys of copper, silver, nickel and cobalt. Using combinatorial
+sputtering, thin-film alloys were prepared on 100 mm wafers with 50%
+compositional grading of each element across the wafer. The films were then
+annealed and investigated for alloy stability. Bioactivity testing was
+performed on both the as-grown alloys and the annealed films using four
+microorganisms -- Phi6, MS2, Bacillus subtilis and Escherichia coli -- as
+surrogates for human viral and bacterial pathogens. Testing showed that after
+30 s of contact with some of the test alloys, Phi6, an enveloped,
+single-stranded RNA bacteriophage that serves as a SARS-CoV 2 surrogate, was
+reduced up to 6.9 orders of magnitude (>99.9999%). Additionally, the
+non-enveloped, double-stranded DNA bacteriophage MS2, and the Gram-negative E.
+coli and Gram-positive B. subtilis bacterial strains showed a 5.0, 6.4, and 5.7
+log reduction in activity after 30, 20 and 10 minutes, respectively.
+Bioactivity in the alloy samples showed a strong dependence on the composition,
+with the log reduction scaling directly with the Cu content. Concentration of
+Cu by phase separation after annealing improved activity in some of the
+samples. The results motivate a variety of themes which can be leveraged to
+design ideal bioactive surfaces.",2205.00886v1
+2022-05-11,Models of Advance Recording Systems: A Multi-timescale Micromagnetic code for granular thin film magnetic recording systems,"Micromagnetic modelling provides the ability to simulate large magnetic
+systems accurately without the computational cost limitation imposed by
+atomistic modelling. Through micromagnetic modelling it is possible to simulate
+systems consisting of thousands of grains over a time range of nanoseconds to
+years, depending upon the solver used. Here we present the creation and release
+of an open-source multi-timescale micromagnetic code combining three key
+solvers: Landau-Lifshitz-Gilbert; Landau-Lifshitz-Bloch; Kinetic Monte Carlo.
+This code, called MARS (Models of Advanced Recording Systems), is capable of
+accurately simulating the magnetisation dynamics in large and structurally
+complex single- and multi-layered granular systems. The short timescale
+simulations are achieved for systems far from and close to the Curie point via
+the implemented Landau-Lifshitz-Gilbert and Landau-Lifshitz-Bloch solvers
+respectively. This enables read/write simulations for general perpendicular
+magnetic recording and also state of the art heat assisted magnetic recording
+(HAMR). The long timescale behaviour is simulated via the Kinetic Monte Carlo
+solver, enabling investigations into signal-to-noise ratio and data longevity.
+The combination of these solvers opens up the possibility of multi-timescale
+simulations within a single software package. For example the entire HAMR
+process from initial data writing and data read back to long term data storage
+is possible via a single simulation using MARS. The use of atomistic
+parameterisation for the material input of MARS enables highly accurate
+material descriptions which provide a bridge between atomistic simulation and
+real world experimentation. Thus MARS is capable of performing simulations for
+all aspects of recording media research and development. This ranges from
+material characterisation and optimisation to system design and implementation.",2205.05263v1
+2023-01-03,Measuring Physical and Electrical Parameters in Free-Living Subjects: Motivating an Instrument to Characterize Analytes of Clinical Importance in Blood Samples,"Significance: A path is described to increase the sensitivity and accuracy of
+body-worn devices used to monitor patient health. This path supports improved
+health management. A wavelength-choice algorithm developed at Mayo demonstrates
+that critical biochemical analytes can be assessed using accurate optical
+absorption curves over a wide range of wavelengths. Aim: Combine the
+requirements for monitoring cardio/electrical, movement, activity, gait,
+tremor, and critical biochemical analytes including hemoglobin makeup in the
+context of body-worn sensors. Use the data needed to characterize clinically
+important analytes in blood samples to drive instrument requirements. Approach:
+Using data and knowledge gained over previously separate research threads, some
+providing currently usable results from more than eighty years back, determine
+analyte characteristics needed to design sensitive and accurate multiuse
+measurement and recording units. Results: Strategies for wavelength selection
+are detailed. Fine-grained, broad-spectrum measurement of multiple analytes
+transmission, absorption, and anisotropic scattering are needed.
+Post-Beer-Lambert, using the propagation of error from small variations, and
+utility functions that include costs and systemic error sources, improved
+measurements can be performed. Conclusions: The Mayo Double-Integrating Sphere
+Spectrophotometer (referred hereafter as MDISS), as described in the companion
+report arXiv:2212.08763, produces the data necessary for optimal component
+choice. These data can provide for robust enhancement of the sensitivity, cost,
+and accuracy of body-worn medical sensors. Keywords: Bio-Analyte,
+Spectrophotometry, Body-worn monitor, Propagation of error, Double-Integrating
+Sphere, Mt. Everest medical measurements, O2SAT
+  Please see also arXiv:2212.08763",2301.00938v2
+2023-01-09,"A Second Earth-Sized Planet in the Habitable Zone of the M Dwarf, TOI-700","We report the discovery of TOI-700 e, a 0.95 R$_\oplus$ planet residing in
+the Optimistic Habitable Zone (HZ) of its host star. This discovery was enabled
+by multiple years of monitoring from NASA's Transiting Exoplanet Survey
+Satellite (TESS) mission. The host star, TOI-700 (TIC 150428135), is a nearby
+(31.1 pc), inactive, M2.5 dwarf ($V_{mag} = 13.15$). TOI-700 is already known
+to host three planets, including the small, HZ planet, TOI-700 d. The new
+planet has an orbital period of 27.8 days and, based on its radius (0.95
+R$_\oplus$), it is likely rocky. TOI-700 was observed for 21 sectors over Years
+1 and 3 of the TESS mission, including 10 sectors at 20-second cadence in Year
+3. Using this full set of TESS data and additional follow-up observations, we
+identify, validate, and characterize TOI-700 e. This discovery adds another
+world to the short list of small, HZ planets transiting nearby and bright host
+stars. Such systems, where the stars are bright enough that follow-up
+observations are possible to constrain planet masses and atmospheres using
+current and future facilities, are incredibly valuable. The presence of
+multiple small, HZ planets makes this system even more enticing for follow-up
+observations.",2301.03617v1
+2023-01-17,Introduction to Non-Invasive Current Estimation (NICE),"It is notoriously difficult to measure instantaneous supply current to a
+device such as an ASIC, FPGA, or CPU without also affecting the instantaneous
+supply voltage and compromising the operation of the device [21]. For decades
+designers have relied on rough estimates of dynamic load currents that
+stimulate a designed Power Delivery Network (PDN). The consequences of
+inaccurate load-current characterization can range from excessive PDN cost and
+lengthened development schedules to poor performance or functional failure.
+This paper will introduce and describe a method to precisely determine
+timedomain current waveforms from a pair of measured timedomain voltage
+waveforms. This NonInvasive Current Estimation (NICE) method is based on
+established twoport network theory along with component and board modeling
+techniques that have been validated through measurements on demonstrative
+circuits. This paper will show that the NICE method works for any transient
+event that can be captured on a digital oscilloscope. Limitations of the method
+and underlying measurements are noted where appropriate. The method is applied
+to a simple PDN with an arbitrary load, and the NICE-derived current waveform
+is verified against an independent measurement by sense resistor. With careful
+component and board modeling, it is possible to calculate current waveforms
+with a root mean square error of less than five percent compared to the
+reference measurement. Current transients that were previously difficult or
+impossible to characterize by any means can now be calculated and displayed
+within seconds of an oscilloscope-trigger event by using NICE. ASIC and FPGA
+manufacturers can now compute the startup current for their device and publish
+the actual waveform, or provide a piecewiselinear SPICE model (PWL source) to
+facilitate design and testing of the regulator and PDN required to support
+their device.",2301.10237v1
+2023-02-08,"Weighted Edit Distance Computation: Strings, Trees and Dyck","Given two strings of length $n$ over alphabet $\Sigma$, and an upper bound
+$k$ on their edit distance, the algorithm of Myers (Algorithmica'86) and Landau
+and Vishkin (JCSS'88) computes the unweighted string edit distance in
+$\mathcal{O}(n+k^2)$ time. Till date, it remains the fastest algorithm for
+exact edit distance computation, and it is optimal under the Strong Exponential
+Hypothesis (STOC'15). Over the years, this result has inspired many
+developments, including fast approximation algorithms for string edit distance
+as well as similar $\tilde{\mathcal{O}}(n+$poly$(k))$-time algorithms for
+generalizations to tree and Dyck edit distances. Surprisingly, all these
+results hold only for unweighted instances.
+  While unweighted edit distance is theoretically fundamental, almost all
+real-world applications require weighted edit distance, where different weights
+are assigned to different edit operations and may vary with the characters
+being edited. Given a weight function $w: \Sigma \cup \{\varepsilon \}\times
+\Sigma \cup \{\varepsilon \} \rightarrow \mathbb{R}_{\ge 0}$ (such that
+$w(a,a)=0$ and $w(a,b)\ge 1$ for all $a,b\in \Sigma \cup \{\varepsilon\}$ with
+$a\ne b$), the goal is to find an alignment that minimizes the total weight of
+edits. Except for the vanilla $\mathcal{O}(n^2)$-time dynamic-programming
+algorithm and its almost trivial $\mathcal{O}(nk)$-time implementation, none of
+the aforementioned developments on the unweighted edit distance apply to the
+weighted variant. In this paper, we propose the first
+$\mathcal{O}(n+$poly$(k))$-time algorithm that computes weighted string edit
+distance exactly, thus bridging a fundamental gap between our understanding of
+unweighted and weighted edit distance. We then generalize this result to
+weighted tree and Dyck edit distances, which lead to a deterministic algorithm
+that improves upon the previous work for unweighted tree edit distance.",2302.04229v1
+2023-03-09,Zonostrophic instabilities in magnetohydrodynamic Kolmogorov flow,"This paper concerns the stability of Kolmogorov flow u = (0, sin x) in the
+infinite (x,y)-plane. A mean magnetic field of strength B0 is introduced and
+the MHD linear stability problem studied for modes with wave-number k in the
+y-direction, and Bloch wavenumber l in the x-direction. The parameters
+governing the problem are Reynolds number 1/nu, magnetic Prandtl number P, and
+dimensionless magnetic field strength B0. The mean magnetic field can be taken
+to have an arbitrary direction in the (x,y)-plane and a mean x-directed flow U0
+can be incorporated.
+  First the paper considers Kolmogorov flow with y-directed mean magnetic
+field, referred to as vertical. Taking l=0, the suppression of the pure
+hydrodynamic instability is observed with increasing field strength B0. A
+branch of strong-field instabilities occurs for magnetic Prandtl number P less
+than unity, as found by A.E. Fraser, I.G. Cresser and P. Garaud (J. Fluid Mech.
+949, A43, 2022). Analytical results using eigenvalue perturbation theory in the
+limit k->0 support the numerics for both weak- and strong-field instabilities,
+and originate in the coupling of large-scale modes with x-wavenumber n=0, to
+smaller-scale modes.
+  The paper considers the case of horizontal or x-directed mean magnetic field.
+The unperturbed state consists of steady, wavey magnetic field lines. As the
+magnetic field is increased, the purely hydrodynamic instability is suppressed
+again, but for stronger fields a new branch of instabilities appears. Allowing
+a non-zero Bloch wavenumber l allows further instability, and in some
+circumstances when the system is hydrodynamically stable, arbitrarily weak
+magnetic fields can give growing modes. Numerical results are presented
+together with eigenvalue perturbation theory in the limits k,l->0. The theory
+gives analytical approximations for growth rates and thresholds in good
+agreement with those computed.",2303.05212v1
+2023-03-30,Fate of entanglement in magnetism under Lindbladian or non-Markovian dynamics and conditions for their transition to Landau-Lifshitz-Gilbert classical dynamics,"It is commonly assumed in spintronics and magnonics that localized spins
+within antiferromagnets are in the N\'{e}el ground state (GS), as well as that
+such state evolves, when pushed out of equilibrium by current or external
+fields, according to the Landau-Lifshitz-Gilbert (LLG) equation viewing
+localized spins as classical vectors of fixed length. On the other hand, the
+true GS of antiferromagnets is highly entangled, as confirmed by very recent
+neutron scattering experiments witnessing their entanglement. Although GS of
+ferromagnets is always unentangled, their magnonic low-energy excitation are
+superpositions of many-body spin states and, therefore, entangled. In this
+study, we initialize quantum Heisenberg ferro- or antiferromagnetic chains
+hosing localized spins $S=1/2$, $S=1$ or $S=5/2$ into unentangled pure state
+and then evolve them by quantum master equations (QMEs) of Lindblad or
+non-Markovian type, derived by coupling localized spins to a bosonic bath (such
+as due to phonons) or by using additional ``reaction coordinate'' in the latter
+case. The time evolution is initiated by applying an external magnetic field,
+and entanglement of time-evolving {\em mixed} quantum states is monitored by
+computing its logarithmic negativity. We find that non-Markovian dynamics
+maintains some degree of entanglement, which shrinks the length of the vector
+of spin expectation values, thereby making the LLG equation inapplicable.
+Conversely, Lindbladian (i.e., Markovian) dynamics ensures that entanglement
+goes to zero, thereby enabling quantum-to-classical (i.e., to LLG) transition
+in all cases -- $S=1/2$, $S=1$ and $S=5/2$ ferromagnet or $S=5/2$
+antiferromagnet -- {\em except} for $S=1/2$ and $S=1$ antiferromagnet. We also
+investigate the stability of entangled antiferromagnetic GS upon suddenly
+coupling it to the bosonic bath.",2303.17596v3
+2024-02-07,"Item-Level Heterogeneous Treatment Effects of Selective Serotonin Reuptake Inhibitors (SSRIs) on Depression: Implications for Inference, Generalizability, and Identification","In analysis of randomized controlled trials (RCTs) with patient-reported
+outcome measures (PROMs), Item Response Theory (IRT) models that allow for
+heterogeneity in the treatment effect at the item level merit consideration.
+These models for ``item-level heterogeneous treatment effects'' (IL-HTE) can
+provide more accurate statistical inference, allow researchers to better
+generalize their results, and resolve critical identification problems in the
+estimation of interaction effects. In this study, we extend the IL-HTE model to
+polytomous data and apply the model to determine how the effect of selective
+serotonin reuptake inhibitors (SSRIs) on depression varies across the items on
+a depression rating scale. We first conduct a Monte Carlo simulation study to
+assess the performance of the polytomous IL-HTE model under a range of
+conditions. We then apply the IL-HTE model to item-level data from 28 RCTs
+measuring the effect of SSRIs on depression using the 17-item Hamilton
+Depression Rating Scale (HDRS-17) and estimate potential heterogeneity by
+subscale (HDRS-6). Our results show that the IL-HTE model provides more
+accurate statistical inference, allows for generalizability of results to
+out-of-sample items, and resolves identification problems in the estimation of
+interaction effects. Our empirical application shows that while the average
+effect of SSRIs on depression is beneficial (i.e., negative) and statistically
+significant, there is substantial IL-HTE, with estimates of the standard
+deviation of item-level effects nearly as large as the average effect. We show
+that this substantial IL-HTE is driven primarily by systematically larger
+effects on the HDRS-6 subscale items. The IL-HTE model has the potential to
+provide new insights for the inference, generalizability, and identification of
+treatment effects in clinical trials using patient reported outcome measures.",2402.04487v1
+1995-02-16,Lyman alpha Emission from High-Redshift Galaxies,"We summarise the results of a deep search for Lyman alpha emission from
+star-forming regions associated with damped Lyman alpha absorption systems and
+conclude that the Lyman alpha luminosity of high redshift galaxies is generally
+less than 10^(42) erg/s . We also present a newly discovered case, in the field
+of the QSO Q2059-360, where the emission is unusually strong, possibly because
+the damped system is close in redshift to the QSO.",9502076v1
+1995-10-12,Limits on diffusive shock acceleration in dense and incompletely ionised media,"The limits imposed on diffusive shock acceleration by upstream ion-neutral
+Alfven wave damping, and by ionisation and Coulomb losses of low energy
+particles, are calculated. Analytic solutions are given for the steady upstream
+wave excitation problem with ion-neutral damping and the resulting escaping
+upstream flux calculated. The time dependent problem is discussed and numerical
+solutions presented. Finally the significance of these results for possible
+observational tests of shock acceleration in supernova remnants is discussed.",9510066v2
+1995-11-28,Damping of GRR instability by direct URCA reactions,"The role of direct URCA reactions in damping of the gravitational radiation
+driven instability is discussed. The temperature at which bulk viscosity
+suppresses completely this instability is calculated.
+  The results are obtained analytically using recent calculations performed in
+the case of bulk viscosity due to the modified URCA processes (Lindblom 1995;
+Yoshida & Eriguchi 1995).
+  The bulk viscosity caused by direct URCA reactions is found to reduce
+significantly the region of temperatures and rotation frequencies where a
+neutron star is subject to GRR instability.",9511136v1
+1997-10-31,Abundances in Damped Lyman-alpha Systems and Chemical Evolution of High Redshift Galaxies,"Recent abundance measurements in damped Lyman-alpha galaxies, supplemented
+with unpublished Keck observations, are discussed. The metallicity distribution
+with cosmic time is examined for clues about the degree of enrichment, the
+onset of initial star formation, and the nature of the galxies. The relative
+abundances of the elements are compared with the abundnce pattern in Galactic
+halo stars and in the Sun, taking into account of the effects of dust
+depletion, in order to gain insight into the stellar processes and the time
+scales by which the enrichment occurred.",9710370v1
+1998-05-08,Exploring the Damped Lyman-alpha Clouds with AXAF,"The High Energy Transmission Grating (HETG) Spectrometer on the Advanced
+X-ray Astrophysics Facility (AXAF) (scheduled for launch in August, 1998) will
+provide a new tool for the study of absorption in the X-ray spectra of high
+redshift quasars due to the material along the line of sight. In this paper we
+try to explore the possibility of using AXAF HETG to detect resonance
+absorption lines from the Damped Lyman-alpha (DLA) clouds.",9805110v1
+1998-05-28,Photon Damping of Waves in Accretion Disks,"MHD turbulence is generally believed to have two important functions in
+accretion disks: it transports angular momentum outward, and the energy in its
+shortest wavelength modes is dissipated into the heat that the disks radiate.
+In this paper we examine a pair of mechanisms which may play an important role
+in regulating the amplitude and spectrum of this turbulence: photon diffusion
+and viscosity. We demonstrate that in radiation pressure-dominated disks,
+photon damping of compressive MHD waves is so rapid that it likely dominates
+all other dissipation mechanisms.",9805358v1
+1998-06-11,Damping of differential rotation in neutron stars,"We derive the transport relaxation times for quasiparticle-vortex scattering
+processes via nuclear force, relevant for the damping of differential rotation
+of superfluids in the quantum liquid core of a neutron star. The proton
+scattering off the neutron vortices provides the dominant resistive force on
+the vortex lattice at all relevant temperatures in the phase where neutrons
+only are in the paired state. If protons are superconducting, a small fraction
+of hyperons and resonances in the normal state would be the dominant source of
+friction on neutron and proton vortex lattices at the core temperatures $T\ge
+10^{7}$ K.",9806156v1
+1999-03-10,Elemental abundances at early times: the nature of Damped Lyman-alpha systems,"The distribution of element abundances with redshift in Damped Ly-alpha (DLA)
+systems can be adequately reproduced by the same model reproducing the halo and
+disk components of the Milky Way Galaxy at different galactocentric distances:
+DLA systems are well represented by normal spiral galaxies in their early
+evolutionary stages.",9903150v1
+1999-07-26,"Are Damped Ly-alpha Systems Large, Galactic Disks ?","The hypothesis that the Damped Ly-alpha systems (DLAs) are large, galactic
+disks (Milky Way sized) is tested by confronting predictions of models of the
+formation and evolution of (large) disk galaxies with observations, in
+particular the Zinc abundance distribution with neutral hydrogen column density
+found for DLAs. A pronounced mismatch is found strongly hinting that the
+majority of DLAs may not be large, galactic disks.",9907349v1
+1999-08-26,Oscillator Strengths and Damping Constants for Atomic Lines in the J and H Bands,"We have built a line list in the near-infrared J and H bands (1.00-1.34,
+1.49-1.80 um) by gathering a series of laboratory and computed line lists.
+Oscillator strengths and damping constants were computed or obtained by fitting
+the solar spectrum.
+  The line list presented in this paper is, to our knowledge, the most complete
+one now available, and supersedes previous lists.",9908296v1
+1999-11-25,Probing Solar Convection,"In the solar convection zone acoustic waves are scattered by turbulent sound
+speed fluctuations. In this paper the scattering of waves by convective cells
+is treated using Rytov's technique. Particular care is taken to include
+diffraction effects which are important especially for high-degree modes that
+are confined to the surface layers of the Sun. The scattering leads to damping
+of the waves and causes a phase shift. Damping manifests itself in the width of
+the spectral peak of p-mode eigenfrequencies. The contribution of scattering to
+the line widths is estimated and the sensitivity of the results on the assumed
+spectrum of the turbulence is studied. Finally the theoretical predictions are
+compared with recently measured line widths of high-degree modes.",9911469v1
+1999-12-14,The Gas Reservoir for present day Galaxies : Damped Ly-alpha Absorption Systems,"We present results from an ongoing search for galaxy counterparts of a
+subgroup of Quasar Absorption Line Systems called Damped Ly-alpha Absorbers
+(DLAs). DLAs have several characteristics that make them essential in the
+process of understanding how galaxies formed in the early universe and evolved
+to the galaxies we see today in the local universe.
+  Finally we compare DLAs with recent findings of a population of starforming
+galaxies at high redshifts, so called Lyman-break galaxies.",9912268v1
+2000-06-22,Nuclear Reaction Rates in a Plasma: The Effect of Highly Damped Modes,"The fluctuation-dissipation theorem is used to evaluate the screening factor
+of nuclear reactions due to the electromagnetic fluctuations in a plasma. We
+show that the commonly used Saltpeter factor is obtained if only fluctuations
+near the plasma eigenfrequency are assumed to be important (\omega \sim
+\omega_{pe}\ll T (\hbar=k_{B}=1)). By taking into account all the fluctuations,
+the highly damped ones, with \omega >\omega_{pe}, as well as those with
+\omega\leq\omega_{pe}, we find that nuclear reaction rates are higher than
+those obtained using the Saltpeter factor, for many interesting plasmas.",0006326v1
+2000-09-06,The Cosmological Evolution of Quasar Damped Lyman-Alpha Systems,"We present results from an efficient, non-traditional survey to discover
+damped Lyman-alpha (DLA) absorption-line systems with neutral hydrogen column
+densities N(HI)>2x10^{20} atoms cm^{-2} and redshifts z<1.65. Contrary to
+previous studies at higher redshift that showed a decrease in the cosmological
+mass density of neutral gas in DLA absorbers, Omega_{DLA}, with time, our
+results indicate that Omega_{DLA} is consistent with remaining constant from
+redshifts z \approx 4 to z \approx 0.5. There is no evidence that Omega_{DLA}
+is approaching the value at z=0. Other interesting results from the survey are
+also presented.",0009098v1
+2001-01-13,Measuring Feedback in Damped Lyman Alpha Systems,"We measure feedback (heating rates) in damped Lyman alpha systems from the
+cooling rate of the neutral gas. Since cooling occurs through [C II] 158 micron
+emission, we infer cooling from C II^{*} 1335.7 absorption lines detected with
+HIRES on the Keck I telescope. The inferred heating rates are about 30 times
+lower than for the Galaxy ISM. At z = 2.8, the implied star formation rate per
+unit area is 10^{-2.4+-0.3} solar masses per kpc^{2} per year, and the the star
+formation rate per unit comoving volume is 10^{-0.8+-0.2} solar masses per
+Mpc^{3} per year. This is the first measurement of star formation rates in
+objects likely to be the progenitors of current galaxies.",0101218v1
+2001-04-18,The First Detection of Cobalt in a Damped Lyman Alpha System,"We present the first ever detection of Cobalt in a Damped Lyman Alpha system
+(DLA) at z = 1.92. In addition to providing important clues to the star
+formation history of these high redshift galaxies, we discuss how studying the
+Co abundance in DLAs may also help to constrain models of stellar
+nucleosynthesis in a regime not probed by Galactic stars.",0104301v1
+2001-05-09,Nuclear reaction rates and energy in stellar plasmas : The effect of highly damped modes,"The effects of the highly damped modes in the energy and reaction rates in a
+plasma are discussed. These modes, with wavenumbers $k \gg k_{D}$, even being
+only weakly excited, with less than $k_{B}T$ per mode, make a significant
+contribution to the energy and screening in a plasma. When the de Broglie
+wavelength is much less than the distance of closest approach of thermal
+electrons, a classical analysis of the plasma can",0105153v1
+2001-07-03,The HI Content and Extent of Low Surface Brightness Galaxies - Could LSB Galaxies be Responsible for Damped Ly-alpha Absorption?,"Low surface brightness galaxies, those galaxies with a central surface
+brightness at least one magnitude fainter than the night sky, are often not
+included in discussions of extragalactic gas at z < 0.1. In this paper we
+review many of the properties of low surface brightness galaxies, including
+recent studies which indicate low surface brightness systems may contribute far
+more to the local HI luminosity function than previously thought. Additionally,
+we use the known (HI) gas properties of low surface brightness galaxies to
+consider their possible contribution to nearby damped Lyman-alpha absorbers.",0107064v1
+2001-09-10,H_2 molecules in damped systems,"Damped Lyman alpha systems seen in the spectra of high-z QSOs arise in
+high-density neutral gas in which molecular hydrogen (H_2) should be
+conspicuous. Systematic searches to detect the H_2 lines redshifted into the
+Lyman alpha forest at <3400\AA are now possible thanks to the unique
+capabilities of UVES on the VLT. Here we summarise the present status of our on
+going programme to search for H_2 in DLAs, discuss the physical conditions in
+the systems where H_2 is detected and the implications of non-detections.",0109155v1
+2001-10-23,A scaling law of interstellar depletions as a tool for abundance studies of Damped Ly alpha systems,"An analytical expression is presented that allows dust depletions to be
+estimated in different types of interstellar environments, including Damped Ly
+alpha systems. The expression is a scaling law of a reference depletion pattern
+and takes into account the possibility that the dust chemical composition may
+vary as a function of the dust-to-metals ratio and of the intrinsic abundances
+of the medium. Preliminary tests and applications of the proposed scaling law
+are briefly reported.",0110499v1
+2002-09-23,Outflows in Galaxies and Damped Ly-alpha System,"Although quasar absorbers, and in particular Damped Lyman-alpha systems
+(DLAs) have proven a valuable tool to study the early Universe, their exact
+nature is so far poorly constrained. It has been suggested that outflows in
+galaxies might account for at least part of the DLA population. Observational
+evidences and models in support of this hypothesis are reviewed, including
+recent observations of Lyman Break Galaxies (LBGs). Observational
+counter-arguments and theoretical limitations are also given. Finally,
+implications of such a model for the environment of galaxies at high-redshifts
+are discussed.",0209463v1
+2004-03-15,The Damping Wing of the Gunn-Peterson Absorption and Lyman-Alpha Emitters in the Pre-Reionization Era,"We use a numerical simulation of cosmological reionization to estimate the
+likelihood of detecting Lyman-alpha emitting galaxies during the
+pre-reionization era. We show that it is possible to find galaxies even at z~9
+that are barely affected by the dumping wing of the Gunn-Peterson absorption
+from the neutral IGM outside of their HII regions. The damping wing becomes
+rapidly more significant at z>9, but even at z>10 is it not inconceivable
+(although quite hard) to see a Lyman-alpha emission line from a star-forming
+galaxy.",0403345v1
+2005-05-28,Cosmic ray transport in MHD turbulence,"Recent advances in understanding of magnetohydrodynamic (MHD) turbulence call
+for revisions in the picture of cosmic ray transport. In this paper we use
+recently obtained scaling laws for MHD modes to obtain the scattering frequency
+for cosmic rays. We account for the turbulence cutoff arising from both
+collisional and collisionless damping. We obtain the scattering rate and show
+that fast modes provide the dominant contribution to cosmic ray scattering for
+the typical interstellar conditions in spite of the fact that fast modes are
+subjected to damping. We determine how the efficiency of the scattering depends
+on the characteristics of ionized media, e.g. plasma $\beta$. We show that
+streaming instability is suppressed by the ambient MHD turbulence.",0505575v1
+2005-06-09,Phantom damping of matter perturbations,"Cosmological scaling solutions are particularly important in solving the
+coincidence problem of dark energy. We derive the equations of sub-Hubble
+linear matter perturbations for a general scalar-field Lagrangian--including
+quintessence, tachyon, dilatonic ghost condensate and k-essence--and solve them
+analytically for scaling solutions. We find that matter perturbations are
+always damped if a phantom field is coupled to dark matter and identify the
+cases in which the gravitational potential is constant. This provides an
+interesting possibility to place stringent observational constraints on scaling
+dark energy models.",0506222v1
+2005-06-22,A Damped Ly-alpha Absorption-line System in an Apparent Void at Redshift 2.38,"We study the contents of an apparent void in the distribution of Ly-alpha
+emitting galaxies at redshift 2.38. We show that this void is not empty, but
+contains a damped Ly-alpha absorption-line system, seen in absorption against
+background QSO 2138-4427. Imaging does not reveal any galaxy associated with
+this absorption-line system, but it contains metals (Fe/H ~ -1.3), and its
+large velocity range (~ 180 km/s) implies a significant mass.",0506525v1
+2005-08-08,Fluorescence in damp air and comments on the radiative life time,"Photon yields in damp air excited by an electron using a Sr90 $\beta$ source
+are compared withthose in dry air. Water vapors considerably reduce the yields,
+however, a further study is needed to evaluate the effects on the energy
+estimation of ultrahigh-energy cosmic rays. The relation of fluorescence
+efficiency to the life time of de-excitation by radiation is discussed.",0508183v1
+2006-08-17,Electron thermal conductivity owing to collisions between degenerate electrons,"We calculate the thermal conductivity of electrons produced by
+electron-electron Coulomb scattering in a strongly degenerate electron gas
+taking into account the Landau damping of transverse plasmons. The Landau
+damping strongly reduces this conductivity in the domain of ultrarelativistic
+electrons at temperatures below the electron plasma temperature. In the inner
+crust of a neutron star at temperatures T < 1e7 K this thermal conductivity
+completely dominates over the electron conductivity due to electron-ion
+(electron-phonon) scattering and becomes competitive with the the electron
+conductivity due to scattering of electrons by impurity ions.",0608371v1
+2006-09-19,"Dust, Metals and Diffuse Interstellar Bands in Damped Lyman Alpha Systems","Although damped Lyman alpha (DLA) systems are usually considered metal-poor,
+it has been suggested that this could be due to observational bias against
+metal-enriched absorbers. I review recent surveys to quantify the particular
+issue of dust obscuration bias and demonstrate that there is currently no
+compelling observational evidence to support a widespread effect due to
+extinction. On the other hand, a small sub-set of DLAs may be metal-rich and I
+review some recent observations of these metal-rich absorbers and the detection
+of diffuse interstellar bands in one DLA at z ~ 0.5.",0609530v1
+2006-11-08,Comments on Viscous Damping of Non-Adiabatic MHD Waves in an Unbounded Solar Coronal Plasma by Kumar and Kumar,"Considering thermal conduction, compressive viscosity and optically thin
+radiation as damping mechanisms for MHD waves, we derive a six-order general
+dispersion relation. We point out a fundamental flaw in the derivation of
+five-order dispersion relation by Kumar and Kumar (2006) who adopt as a basis
+vector. The correct definition of the motion in the x-z plane (2-D vector
+space) stems from the two independent variables, namely .",0611252v2
+2007-01-10,Non-gaussianity in fluctuations from warm inflation,"The scalar mode density perturbations in a the warm inflationary scenario are
+analysed with a view to predicting the amount of non-gaussianity produced by
+this scenario. The analysis assumes that the inflaton evolution is strongly
+damped by the radiation, with damping terms that are temperature independent.
+Entropy fluctuations during warm inflation play a crucial role in generating
+non-gaussianity and result in a distinctive signal which should be observable
+by the Planck satellite.",0701302v2
+1998-05-22,WKB for a damped spin,"The master equation for a damped spin well known from the theory of
+superradiance, is written as a finite-difference equation and solved by a
+WKB-like method. The propagator thus obtained looks like the van Vleck
+propagator of a certain classical Hamiltonian system with one degree of
+freedom. A new interpretation is provided of the temporal broadening of
+initially sharp probability distributions as the analogue of the spreading of
+the quantum mechanical wave packet.",9805018v1
+1998-11-04,Cascades of energy and helicity in the GOY shell model of turbulence,"The effect of extreme hyperviscous damping, $\nu k_n^p, p=\infty$ is studied
+numerically in the GOY shell model of turbulence. It has resently been
+demonstrated [Leveque and She, Phys. Rev. Lett, 75,2690 (1995)] that the
+inertial range scaling in the GOY model is non-universal and depending on the
+viscous damping. The present study shows that the deviation from Kolmogorov
+scaling is due to the cascade of the second inviscid invariant. This invariant
+is non-positive definite and in this sense analogous to the helicity of 3D
+turbulent flow.",9811009v1
+1994-02-04,Effects of Disorder in a Dilute Bose Gas,"We discuss the effects of a weak random external potential on the properties
+of the dilute Bose gas at zero temperature. The results recently obtained by
+Huang and Meng for the depletion of the condensate and of the superfluid
+density are recovered. Results for the shift of the velocity of sound as well
+as for its damping due to collisions with the external field are presented. The
+damping of phonons is calculated also for dense superfluids. (submitted to
+Phys.Rev.B)",9402015v1
+1995-02-10,The influence of structure disorder on mean atomic momentum fluctuations and a spin-wave spectrum,"The relation between atomic momenta fluctuations and density fluctuations is
+obtained in frames of mean-field approximation. Using two-time temperature
+Green functions within Tyablikov approximation the equations for spin
+excitation energy and damping are obtained. The asymptotics of energy and
+damping in the long-wave limit are investigated and the anomalous behaviour of
+spin-wave stiffness constant is discussed.",9502042v1
+1997-02-13,"Comment on ""Collective Excitations of a Bose-Einstein Condensate in a Magnetic Trap""","We calculate the damping rate of collective excitations for a nearly pure
+Bose-Einstein condensate regarding the recent experiments in MIT [M.-O. Mews et
+al, Phys. Rev. Lett. 77, 988 (1996)]. The decay time of collective excitations
+obtained in our theoretical calculations agrees well with their experimental
+result. We argue that the damping of collective excitations is due to thermal
+contributions rather than interactions between collective modes.",9702122v1
+1997-08-14,Landau damping in dilute Bose gases,"Landau damping in weakly interacting Bose gases is investigated by means of
+perturbation theory. Our approach points out the crucial role played by
+Bose-Einstein condensation and yields an explicit expression for the decay rate
+of elementary excitations in both uniform and non uniform gases. Systematic
+results are derived for the phonon width in homogeneous gases interacting with
+repulsive forces. Special attention is given to the low and high temperature
+regimes.",9708104v1
+1997-11-07,Coulomb suppression of NMR coherence peak in fullerene superconductors,"The suppressed NMR coherence peak in the fullerene superconductors is
+explained in terms of the dampings in the superconducting state induced by the
+Coulomb interaction between conduction electrons. The Coulomb interaction,
+modelled in terms of the onsite Hubbard repulsion, is incorporated into the
+Eliashberg theory of superconductivity with its frequency dependence considered
+self-consistently at all temperatures. The vertex correction is also included
+via the method of Nambu. The frequency dependent Coulomb interaction induces
+the substantial dampings in the superconducting state and, consequently,
+suppresses the anticipated NMR coherence peak of fullerene superconductors as
+found experimentally.",9711060v2
+1997-12-09,The Sound of Sonoluminescence,"We consider an air bubble in water under conditions of single bubble
+sonoluminescence (SBSL) and evaluate the emitted sound field nonperturbatively
+for subsonic gas-liquid interface motion. Sound emission being the dominant
+damping mechanism, we also implement the nonperturbative sound damping in the
+Rayleigh-Plesset equation for the interface motion. We evaluate numerically the
+sound pulse emitted during bubble collapse and compare the nonperturbative and
+perturbative results, showing that the usual perturbative description leads to
+an overestimate of the maximal surface velocity and maximal sound pressure. The
+radius vs. time relation for a full SBSL cycle remains deceptively unaffected.",9712097v1
+1998-07-02,Linear systems with adiabatic fluctuations,"We consider a dynamical system subjected to weak but adiabatically slow
+fluctuations of external origin. Based on the ``adiabatic following''
+approximation we carry out an expansion in \alpha/|\mu|, where \alpha is the
+strength of fluctuations and 1/|\mu| refers to the time scale of evolution of
+the unperturbed system to obtain a linear differential equation for the average
+solution. The theory is applied to the problems of a damped harmonic oscillator
+and diffusion in a turbulent fluid. The result is the realization of
+`renormalized' diffusion constant or damping constant for the respective
+problems. The applicability of the method has been critically analyzed.",9807031v1
+1998-12-02,Vortex lattice melting and the damping of the dHvA oscillations in the mixed state,"Phase fluctuations in the superconducting order parameter, which are
+responsible for the melting of the Abrikosov vortex lattice below the mean
+field $H_{c2}$, are shown to dramatically enhance the scattering of
+quasi-particles by the fluctuating pair potential, thus leading to enhanced
+damping of the dHvA oscillations in the liquid mixed state. This effect is
+shown to quantitatively account for the detailed field dependence of the dHvA
+amplitude observed recently in the mixed state of a Quasi 2D organic SC.",9812040v1
+1999-01-19,Damping of Growth Oscillations,"Computer simulations and scaling theory are used to investigate the damping
+of oscillations during epitaxial growth on high-symmetry surfaces. The
+crossover from smooth to rough growth takes place after the deposition of
+(D/F)^\delta monolayers, where D and F are the surface diffusion constant and
+the deposition rate, respectively, and the exponent \delta=2/3 on a
+two-dimensional surface. At the transition, layer-by-layer growth becomes
+desynchronized on distances larger than a layer coherence length proportional
+l^2, where l is a typical distance between two-dimensional islands in the
+submonolayer region of growth.",9901178v1
+1999-06-15,Temperature-induced resonances and Landau damping of collective modes in Bose-Einstein condensed gases in spherical traps,"Interaction between collective monopole oscillations of a trapped
+Bose-Einstein condensate and thermal excitations is investigated by means of
+perturbation theory. We assume spherical symmetry to calculate the matrix
+elements by solving the linearized Gross-Pitaevskii equations. We use them to
+study the resonances of the condensate induced by temperature when an external
+perturbation of the trapping frequency is applied and to calculate the Landau
+damping of the oscillations.",9906214v1
+1999-08-03,Kinetic Theory of Collective Modes in Atomic Clouds above the Bose-Einstein Transition Temperature,"We calculate frequencies and damping rates of the lowest collective modes of
+a dilute Bose gas confined in an anisotropic trapping potential above the
+Bose-Einstein transition temperature. From the Boltzmann equation with a
+simplified collision integral we derive a general dispersion relation that
+interpolates between the collisionless and hydrodynamic regimes. In the case of
+axially symmetric traps we obtain explicit expressions for the frequencies and
+damping rates of the lowest modes in terms of a phenomenological collision
+time. Our results are compared with microscopic calculations and experiments.",9908043v1
+1999-09-01,Normal Fermi Liquid Behavior of Quasiholes in the Spin-Polaron Model for Copper Oxides,"Based on the t-J model and the self-consistent Born approximation, the
+damping of quasiparticle hole states near the Fermi surface is calculated in a
+low doping regime. Renormalization of spin-wave excitations due to hole doping
+is taken into account. The damping is shown to be described by a familiar form
+$\text{Im}\Sigma({\bf k}^{\prime},\epsilon)\propto (\epsilon^{2}/
+\epsilon_{F})\ln(\epsilon/ \epsilon_{F})$ characteristic of the 2-dimensional
+Fermi liquid, in contrast with the earlier statement reported by Li and Gong
+[Phys. Rev. B {\bf 51}, 6343 (1995)] on the marginal Fermi liquid behavior of
+quasiholes.",9909020v1
+1999-12-01,Impurity relaxation mechanism for dynamic magnetization reversal in a single domain grain,"The interaction of coherent magnetization rotation with a system of two-level
+impurities is studied. Two different, but not contradictory mechanisms, the
+`slow-relaxing ion' and the `fast-relaxing ion' are utilized to derive a system
+of integro-differential equations for the magnetization. In the case that the
+impurity relaxation rate is much greater than the magnetization precession
+frequency, these equations can be written in the form of the Landau-Lifshitz
+equation with damping. Thus the damping parameter can be directly calculated
+from these microscopic impurity relaxation processes.",9912014v1
+2000-02-16,Dissipative dynamics of Bose condensates in optical cavities,"We study the zero temperature dynamics of Bose-Einstein condensates in driven
+high-quality optical cavities in the limit of large atom-field detuning. We
+calculate the stationary ground state and the spectrum of coupled atom and
+field mode excitations for standing wave cavities as well as for travelling
+wave cavities. Finite cavity response times lead to damping or controlled
+amplification of these excitations. Analytic solutions in the Lamb-Dicke
+expansion are in good agreement with numerical results for the full problem and
+show that oscillation frequencies and the corresponding damping rates are
+qualitatively different for the two cases.",0002247v1
+2000-03-27,Effect of memory and dynamical chaos in long Josephson junctions,"A long Josephson junction in a constant external magnetic field and in the
+presence of a dc bias current is investigated. It is shown that the system,
+simulated by the sine-Gorgon equation, ""remembers"" a rapidly damping initial
+perturbation and final asymptotic states are determined exactly with this
+perturbation. Numerical solving of the boundary sine-Gordon problem and
+calculations of Lyapunov indices show that this system has a memory even when
+it is in a state of dynamical chaos, i.e., dynamical chaos does not destroy
+initial information having a character of rapidly damping perturbation.",0003421v1
+2000-09-13,Oscillations of the superconducting order parameter in a ferromagnet,"Planar tunneling spectroscopy reveals damped oscillations of the
+superconducting order parameter induced into a ferromagnetic thin film by the
+proximity effect. The oscillations are due to the finite momentum transfer
+provided to Cooper pairs by the splitting of the spin up and down bands in the
+ferromagnet. As a consequence, for negative values of the superconducting order
+parameter the tunneling spectra are capsized (""$\pi$-state""). The oscillations'
+damping and period are set by the same length scale, which depends on the spin
+polarization.",0009192v1
+2000-09-29,Damping and revivals of collective oscillations in a finite-temperature model of trapped Bose-Einstein condensation,"We utilize a two-gas model to simulate collective oscillations of a
+Bose-Einstein condensate at finite temperatures. The condensate is described
+using a generalized Gross-Pitaevskii equation, which is coupled to a thermal
+cloud modelled by a Monte Carlo algorithm. This allows us to include the
+collective dynamics of both the condensed and non-condensed components
+self-consistently. We simulate quadrupolar excitations, and measure the damping
+rate and frequency as a function of temperature. We also observe revivals in
+condensate oscillations at high temperatures, and in the thermal cloud at low
+temperature. Extensions of the model to include non-equilibrium effects and
+describe more complex phenomena are discussed.",0009468v1
+2001-04-18,Effective rate equations for the over-damped motion in fluctuating potentials,"We discuss physical and mathematical aspects of the over-damped motion of a
+Brownian particle in fluctuating potentials. It is shown that such a system can
+be described quantitatively by fluctuating rates if the potential fluctuations
+are slow compared to relaxation within the minima of the potential, and if the
+position of the minima does not fluctuate. Effective rates can be calculated;
+they describe the long-time dynamics of the system. Furthermore, we show the
+existence of a stationary solution of the Fokker-Planck equation that describes
+the motion within the fluctuating potential under some general conditions. We
+also show that a stationary solution of the rate equations with fluctuating
+rates exists.",0104330v1
+2001-09-05,Spin Excitations in a Fermi Gas of Atoms,"We have experimentally investigated a spin excitation in a quantum degenerate
+Fermi gas of atoms. In the hydrodynamic regime the damping time of the
+collective excitation is used to probe the quantum behavior of the gas. At
+temperatures below the Fermi temperature we measure up to a factor of 2
+reduction in the excitation damping time. In addition we observe a strong
+excitation energy dependence for this quantum statistical effect.",0109098v2
+2001-10-09,Freezing of a Stripe Liquid,"The existence of a stripe-liquid phase in a layered nickelate,
+La(1.725)Sr(0.275)NiO(4), is demonstrated through neutron scattering
+measurements. We show that incommensurate magnetic fluctuations evolve
+continuously through the charge-ordering temperature, although an abrupt
+decrease in the effective damping energy is observed on cooling through the
+transition. The energy and momentum dependence of the magnetic scattering are
+parametrized with a damped-harmonic-oscillator model describing overdamped
+spin-waves in the antiferromagnetic domains defined instantaneously by charge
+stripes.",0110191v2
+2001-12-13,Magnon softening and damping in the ferromagnetic manganites due to orbital correlations,"We present a theory for spin excitations in ferromagnetic metallic manganites
+and demonstrate that orbital fluctuations have strong effects on the magnon
+dynamics in the case these compounds are close to a transition to an orbital
+ordered state. In particular we show that the scattering of the spin
+excitations by low-lying orbital modes with cubic symmetry causes both the
+magnon softening and damping observed experimentally.",0112252v2
+2002-01-16,Quantum Spin dynamics of the Bilayer Ferromagnet La(1.2)Sr(1.8)Mn2O7,"We construct a theory of spin wave excitations in the bilayer manganite
+La(1.2)Sr(1.8)Mn2O7 based on the simplest possible double-exchange model, but
+including leading quantum corrections to the spin wave dispersion and damping.
+Comparison is made with recent inelastic neutron scattering experiments. We
+find that quantum effects account for some part of the measured damping of spin
+waves, but cannot by themselves explain the observed softening of spin waves at
+the zone boundary. Furthermore a doping dependence of the total spin wave
+dispersion and the optical spin wave gap is predicted.",0201269v1
+2002-02-21,Dynamics of a Bose-Einstein condensate at finite temperature in an atomoptical coherence filter,"The macroscopic coherent tunneling through the barriers of a periodic
+potential is used as an atomoptical filter to separate the condensate and the
+thermal components of a $^{87}$Rb mixed cloud. We condense in the combined
+potential of a laser standing-wave superimposed on the axis of a cigar-shape
+magnetic trap and induce condensate dipole oscillation in the presence of a
+static thermal component. The oscillation is damped due to interaction with the
+thermal fraction and we investigate the role played by the periodic potential
+in the damping process.",0202369v1
+2002-03-11,A Damping of the de Haas-van Alphen Oscillations in the superconducting state,"Deploying a recently developed semiclassical theory of quasiparticles in the
+superconducting state we study the de Haas-van Alphen effect. We find that the
+oscillations have the same frequency as in the normal state but their amplitude
+is reduced. We find an analytic formulae for this damping which is due to
+tunnelling between semiclassical quasiparticle orbits comprising both
+particle-like and hole-like segments. The quantitative predictions of the
+theory are consistent with the available data.",0203224v1
+2002-03-26,Measurement induced quantum-classical transition,"A model of an electrical point contact coupled to a mechanical system
+(oscillator) is studied to simulate the dephasing effect of measurement on a
+quantum system. The problem is solved at zero temperature under conditions of
+strong non-equilibrium in the measurement apparatus. For linear coupling
+between the oscillator and tunneling electrons, it is found that the oscillator
+dynamics becomes damped, with the effective temperature determined by the
+voltage drop across the junction. It is demonstrated that both the quantum
+heating and the quantum damping of the oscillator manifest themselves in the
+current-voltage characteristic of the point contact.",0203521v3
+2002-07-04,Fluctuations and correlations in hexagonal optical patterns,"We analyze the influence of noise in transverse hexagonal patterns in
+nonlinear Kerr cavities. The near field fluctuations are determined by the
+neutrally stable Goldstone modes associated to translational invariance and by
+the weakly damped soft modes. However these modes do not contribute to the far
+field intensity fluctuations which are dominated by damped perturbations with
+the same wave vectors than the pattern. We find strong correlations between the
+intensity fluctuations of any arbitrary pair of wave vectors of the pattern.
+Correlation between pairs forming 120 degrees is larger than between pairs
+forming 180 degrees, contrary to what a naive interpretation of emission in
+terms of twin photons would suggest.",0207127v2
+2002-09-19,Damping of long-wavelength collective excitations in quasi-onedimensional Fermi liquids,"The imaginary part of the exchange-correlation kernel in the longitudinal
+current-current response function of a quasi-onedimensional Fermi liquid is
+evaluated by an approximate decoupling in the equation of motion for the
+current density, which accounts for processes of excitation of two
+particle-hole pairs. The two-pair spectrum determines the intrinsic damping
+rate of long-wavelength collective density fluctuations, which is calculated
+and contrasted with a result previously obtained for a clean Luttinger liquid.",0209455v1
+2002-11-05,Magnetic fluctuations and resonant peak in cuprates: a microscopic theory,"The theory for the dynamical spin susceptibility within the t-J model is
+developed, as relevant for the resonant magnetic peak and normal-state magnetic
+response in superconducting (SC) cuprates. The analysis is based on the
+equations of motion for spins and the memory-function presentation of magnetic
+response where the main damping of the low-energy spin collective mode comes
+from the decay into fermionic degrees of freedom. It is shown that the damping
+function at low doping is closely related to the c-axis optical conductivity.
+The analysis reproduces doping-dependent features of the resonant magnetic
+scattering.",0211090v1
+2002-11-20,Damping of Nodal Fermions Caused by a Dissipative Mode,"Using a $d_{x^2 - y^2}$ superconductor in 2+1 dimensions we show that the
+Nambu Goldstone fluctuations are replaced by dissipative excitations. We find
+that the nodal quasi-particles damping is caused by the strong dissipative
+excitations near the nodal points. As a result we find that the scattering
+rates are linear in frequency and not cubic as predicted in the literature for
+the ``d'' wave superconductors. Our results explain the recent angle resolved
+photoemission spectroscopy and optical conductivity in the BSCCO high $T_c$
+compounds.",0211440v1
+2003-05-27,Dynamics of a classical gas including dissipative and mean field effects,"By means of a scaling ansatz, we investigate an approximated solution of the
+Boltzmann-Vlasov equation for a classical gas. Within this framework, we derive
+the frequencies and the damping of the collective oscillations of a
+harmonically trapped gas and we investigate its expansion after release of the
+trap. The method is well suited to studying the collisional effects taking
+place in the system and in particular to discussing the crossover between the
+hydrodynamic and the collisionless regimes. An explicit link between the
+relaxation times relevant for the damping of the collective oscillations and
+for the expansion is established.",0305624v1
+2003-07-21,Chaotic scattering of a quantum particle weakly coupled to a very complicated background,"Effect of a complicated many-body environment is analyzed on the chaotic
+motion of a quantum particle in a mesoscopic ballistic structure. The dephasing
+and absorption phenomena are treated on the same footing in the framework of a
+model which is free of the ambiguities inherent to earlier models. The
+single-particle doorway resonance states excited via an external channel are
+damped not only because of the escape onto such channels but also due to
+ulterior population of long-lived background states, the resulting internal
+damping being uniquely characterized by the spreading width. On the other hand,
+the formation of the fine-structure resonances strongly enhances the delay time
+fluctuations thus broadening the delay time distribution.",0307496v1
+2003-09-24,Landau Damping in a 2D Electron Gas with Imposed Quantum Grid,"Dielectric properties of semiconductor substrate with imposed two dimensional
+(2D) periodic grid of quantum wires or nanotubes (quantum crossbars, QCB) are
+studied. It is shown that a capacitive contact between QCB and semiconductor
+substrate does not destroy the Luttinger liquid character of the long wave QCB
+excitations. However, the dielectric losses of a substrate surface are
+drastically modified due to diffraction processes on the QCB superlattice.
+QCB-substrate interaction results in additional Landau damping regions of the
+substrate plasmons. Their existence, form and the density of losses are
+strongly sensitive to the QCB lattice constant.",0309546v2
+2003-11-21,Self-stabilised fractality of sea-coasts through damped erosion,"Erosion of rocky coasts spontaneously creates irregular seashores. But the
+geometrical irregularity, in turn, damps the sea-waves, decreasing the average
+wave amplitude. There may then exist a mutual self-stabilisation of the waves
+amplitude together with the irregular morphology of the coast. A simple model
+of such stabilisation is studied. It leads, through a complex dynamics of the
+earth-sea interface, to the appearance of a stationary fractal seacoast with
+dimension close to 4/3. Fractal geometry plays here the role of a morphological
+attractor directly related to percolation geometry.",0311509v1
+2003-12-10,Exciton-LO-phonon dynamics in InAs/GaAs quantum dots: Effects of zone-edge phonon damping,"The dynamics of an exciton-LO-phonon system after an ultrafast optical
+excitation in an InAs/GaAs quantum dot is studied theoretically. Influence of
+anharmonic phonon damping and its interplay with the phonon dispersion is
+analyzed. The signatures of the zone-edge decay process in the absorption
+spectrum and time evolution are highlighted, providing a possible way of
+experimental investigation on phonon anharmonicity effects.",0312256v2
+2004-01-13,Vortex waves and the onset of turbulence in $^3$He-B,"In a recent experiment Finne et al. discovered an intrinsic condition for the
+onset of quantum turbulence in $^3$He-B, that q=alpha/(1-alpha')<1, where alpha
+and alpha' are mutual friction parameters. The authors argued that this
+condition corresponds to Kelvin waves which are marginally damped, so for q>1
+Kelvin waves cannot grow in amplitude and trigger vortex reconnections and
+turbulence. By analysing both axisymmetric and non-axisymmetric modes of
+oscillations of a rotating superfluid, we confirm that in the long axial
+wavelength limit the simple condition q=1 is indeed the crossover between
+damped and propagating Kelvin waves.",0401212v1
+2004-01-28,Long lived acoustic vibrational modes of an embedded nanoparticle,"Classical continuum elastic calculations show that the acoustic vibrational
+modes of an embedded nanoparticle can be lightly damped even when the
+longitudinal plane wave acoustic impedances $Z_o=\rho v_L$ of the nanoparticle
+and the matrix are the same. It is not necessary for the matrix to be less
+dense or softer than the nanoparticle in order to have long lived vibrational
+modes. Continuum boundary conditions do not always accurately reflect the
+microscropic nature of the interface between nanoparticle and matrix, and a
+multi-layer model of the interface reveals the possibility of additional
+reduction of mode damping.",0401579v2
+2004-07-20,Dynamics of a trapped ultracold two-dimensional atomic gas,"This article is devoted to the study of two-dimensional Bose gases
+harmonically confined. We first summarize their equilibrium properties. For
+such a gas above the critical temperature, we also derive the frequencies and
+the damping of the collective oscillations and we investigate its expansion
+after releasing of the trap. The method is well suited to study the collisional
+effects taking place in the system and in particular to discuss the crossover
+between the hydrodynamic and the collisionless regimes. We establish the link
+between the relaxation times relevant for the damping of the collective
+oscillations and for the time-of-flight expansion. We also evaluate the
+collision rate and its relationship with the relaxation time.",0407522v1
+2004-12-06,Thermal wave packets induced by attosecond laser pulses,"In this paper the dynamics of the interaction of attosecond laser pulses with
+matter is investigated. It will be shown that the master equation: modified
+Klein-Gordon equation describes the propagation of the heatons. Heatons are the
+thermal wave packets. When the duration of the laser pulsees \delta t is of the
+order of attosecond the heaton-thermal wave packets are nondispersive objects.
+For \delta t \to \infty, the heatons are damped with damping factor of the
+order of relaxation time for thermal processes.
+  Key words: Temperature fields; Attosecond laser pulses; Heatons; Modified
+Klein-Gordon equation.",0412126v1
+2005-04-12,Nonlinear response and discrete breather excitation in driven micro-mechanical cantilever arrays,"We explain the origin of the generation of discrete breathers (DBs) in
+experiments on damped and driven micromechanical cantilever arrays (M.Sato et
+al. Phys. Rev. Lett. {\bf 90}, 044102, 2003). Using the concept of the
+nonlinear response manifold (NLRM) we provide a systematic way to find the
+optimal parameter regime in damped and driven lattices where DBs exist. Our
+results show that DBs appear via a new instability of the NLRM different from
+the anticipated modulational instability (MI) known for conservative systems.
+We present several ways of exciting DBs, and compare also to experimental
+studies of exciting and destroying DBs in antiferromagnetic layered systems.",0504298v1
+2005-05-14,Monopole Oscillations and Dampings in Boson and Fermion Mixture in the Time-Dependent Gross-Pitaevskii and Vlasov Equations,"We construct a dynamical model for the time evolution of the boson-fermion
+coexistence system. The dynamics of bosons and fermions are formulated with the
+time-dependent Gross-Pitaevsky equation and the Vlasov equation. We thus study
+the monopole oscillation in the bose-fermi mixture. We find that large damping
+exists for fermion oscillations in the mixed system even at zero temperature.",0505357v1
+2005-10-13,Superconducting Flywheel Model for Energy Storage Applications,"In order to explore the complexity and diversity of the flywheels' dynamics,
+we have developed the real-physics computer model of a universal mechanical
+rotor. Due to an arbitrary external force concept, the model can be adjusted to
+operate identical to the real experimental prototype. Taking the high-speed
+magnetic rotor on superconducting bearings as the prototype, the law for the
+energy loss in real high temperature superconducting bearings has been derived.
+Varying the laws of damping and elasticity in the system, we have found a way
+to effectively damp the parasitic resonances and minimize the loss of energy
+storage.",0510346v1
+2005-11-05,Ratchet Effect in Magnetization Reversal of Stoner Particles,"A new strategy is proposed aimed at substantially reducing the minimal
+magnetization switching field for a Stoner particle. Unlike the normal method
+of applying a static magnetic field which must be larger than the magnetic
+anisotropy, a much weaker field, proportional to the damping constant in the
+weak damping regime, can be used to switch the magnetization from one state to
+another if the field is along the motion of the magnetization. The concept is
+to constantly supply energy to the particle from the time-dependent magnetic
+field to allow the particle to climb over the potential barrier between the
+initial and the target states.",0511135v1
+2005-12-03,Apparent vibrational side-bands in pi-conjugated systems: the case of distyrylbenzene,"The photoluminescence (PL) spectra of dilute solution and single crystals of
+distyrylbenzene show unique temperature dependent vibronic structures. The
+characteristic single frequency progression at high temperatures is modulated
+by a low frequency progression series at low temperatures. None of the series
+side band modes corresponds to any of the distyrylbenzene Raman frequencies. We
+explain these PL properties using a time dependent model with temperature
+dependent damping, in which the many-mode system is effectively transformed to
+two- and then to a single ""apparent"" mode as damping increases.",0512067v1
+2006-05-26,Thermo-Plasma Polariton within Scaling Theory of Single-Layer Graphene,"Electrodynamics of single-layer graphene is studied in the scaling regime. At
+any finite temperature, there is a weakly damped collective thermo-plasma
+polariton mode whose dispersion and wavelength dependent damping is determined
+analytically. The electric and magnetic fields associated with this mode decay
+exponentially in the direction perpendicular to the graphene layer, but unlike
+the surface plasma polariton modes of metals, the decay length and the mode
+frequency are strongly temperature dependent. This may lead to new ways of
+generation and manipulation of these modes.",0605642v1
+2006-12-18,Shear viscosity and damping for a Fermi gas in the unitarity limit,"The shear viscosity of a two-component Fermi gas in the normal phase is
+calculated as a function of temperature in the unitarity limit, taking into
+account strong-coupling effects that give rise to a pseudogap in the spectral
+density for single-particle excitations. The results indicate that recent
+measurements of the damping of collective modes in trapped atomic clouds can be
+understood in terms of hydrodynamics, with a decay rate given by the viscosity
+integrated over an effective volume of the cloud.",0612460v2
+2007-02-07,Damping of antiferromagnetic spin waves by valence fluctuations in the double layer perovskite YBaFe2O5,"Inelastic neutron scattering experiments show that spin dynamics in the
+charge ordered insulating ground state of the double-layer perovskite YBaFe2O5
+is well described in terms of eg superexchange interactions. Above the Verwey
+transition at TV = 308 K, t2g double exchange-type conduction within
+antiferromagnetic FeO2--BaO--FeO2 double layers proceeds by an electron hopping
+process that requires a spin flip of the five-fold coordinated Fe ions, costing
+an energy 5<J>S^2 of approximately 0.1 eV. The hopping process disrupts
+near-neighbor spin correlations, leading to massive damping of zone-boundary
+spin waves.",0702181v1
+2007-02-20,Spin Drag and Spin-Charge Separation in Cold Fermi Gases,"Low-energy spin and charge excitations of one-dimensional interacting
+fermions are completely decoupled and propagate with different velocities.
+These modes however can decay due to several possible mechanisms. In this paper
+we expose a new facet of spin-charge separation: not only the speeds but also
+the damping rates of spin and charge excitations are different. While the
+propagation of long-wavelength charge excitations is essentially ballistic,
+spin propagation is intrinsically damped and diffusive. We suggest that cold
+Fermi gases trapped inside a tight atomic waveguide offer the opportunity to
+measure the spin-drag relaxation rate that controls the broadening of a spin
+packet.",0702466v1
+1996-07-23,Quasinormal modes of nearly extreme Reissner-Nordstrom black holes,"We present detailed calculations of the quasinormal modes of
+Reissner-Nordstrom black holes. While the first few, slowly damped, modes
+depend on the charge of the black hole in a relatively simple way, we find that
+the rapidly damped modes show several peculiar features. The higher modes
+generally spiral into the value for the extreme black hole as the charge
+increases. We also discuss the possible existence of a purely imaginary mode
+for the Schwarzschild black hole: Our data suggest that there is a quasinormal
+mode that limits to $\omega M = -2i$ as $Q\to 0$.",9607054v1
+1996-08-22,Gravitational Ionization: A Chaotic Net in the Kepler System,"The long term nonlinear dynamics of a Keplerian binary system under the
+combined influences of gravitational radiation damping and external tidal
+perturbations is analyzed. Gravitational radiation reaction leads the binary
+system towards eventual collapse, while the external periodic perturbations
+could lead to the ionization of the system via Arnold diffusion. When these two
+opposing tendencies nearly balance each other, interesting chaotic behavior
+occurs that is briefly studied in this paper. It is possible to show that
+periodic orbits can exist in this system for sufficiently small damping.
+Moreover, we employ the method of averaging to investigate the phenomenon of
+capture into resonance.",9608054v1
+1999-11-11,Inertial Control of the VIRGO Superattenuator,"The VIRGO superattenuator (SA) is effective in depressing the seismic noise
+below the thermal noise level above 4 Hz. On the other hand, the residual
+mirror motion associated to the SA normal modes can saturate the dynamics of
+the interferometer locking system. This motion is reduced implementing a
+wideband (DC-5 Hz) multidimensional control (the so called inertial damping)
+which makes use of both accelerometers and position sensors and of a DSP
+system. Feedback forces are exerted by coil-magnet actuators on the top of the
+inverted pendulum. The inertial damping is successful in reducing the mirror
+motion within the requirements. The results are presented.",9911044v1
+2002-10-30,Massive charged scalar field in a Reissner-Nordstrom black hole background: quasinormal ringing,"We compute characteristic (quasinormal) frequencies corresponding to decay of
+a massive charged scalar field in a Reissner-Nordstrom black hole background.
+It proves that, contrary to the behavior at very late times, at the stage of
+quasinormal ringing the neutral perturbations will damp slower than the charged
+ones. In the limit of the extremal black hole the damping rate of charged and
+neutral perturbations coincides. Possible connection of this with the critical
+collapse in a massive scalar electrodynamics is discussed.",0210105v3
+2003-03-20,Dirac Quasi-Normal Modes in Schwarzschild Black Hole Spacetimes,"We evaluate both the massless and the massive Dirac quasi-normal mode
+frequencies in the Schwarzschild black hole spacetime using the WKB
+approximation. For the massless case, we find that, similar to those for the
+integral spin fields, the real parts of the frequencies increase with the
+angular momentum number $\kappa$, while the imaginary parts or the dampings
+increase with the mode number $n$ for fixed $\kappa$. For the massive case, the
+oscillation frequencies increase with the mass $m$ of the field, while the
+dampings decrease. Fields with higher masses will therefore decay more slowly.",0303078v1
+2003-07-31,Effects of electrical charging on the mechanical Q of a fused silica disk,"We report on the effects of an electrical charge on mechanical loss of a
+fused silica disk. A degradation of Q was seen that correlated with charge on
+the surface of the sample. We examine a number of models for charge damping,
+including eddy current damping and loss due to polarization. We conclude that
+rubbing friction between the sample and a piece of dust attracted by the
+charged sample is the most likely explanation for the observed loss.",0308001v1
+2004-09-15,Rippled Cosmological Dark Matter from Damped Oscillating Newton Constant,"Let the reciprocal Newton 'constant' be an apparently non-dynamical
+Brans-Dicke scalar field damped oscillating towards its General Relativistic
+VEV. We show, without introducing additional matter fields or dust, that the
+corresponding cosmological evolution averagely resembles, in the Jordan frame,
+the familiar dark radiation -> dark matter -> dark energy domination sequence.
+The fingerprints of our theory are fine ripples, hopefully testable, in the FRW
+scale factor; they die away at the General Relativity limit. The possibility
+that the Brans-Dicke scalar also serves as the inflaton is favorably examined.",0409059v2
+2004-10-06,Thermoelastic-damping noise from sapphire mirrors in a fundamental-noise-limited interferometer,"We report the first high-precision interferometer using large sapphire
+mirrors, and we present the first direct, broadband measurements of the
+fundamental thermal noise in these mirrors. Our results agree well with the
+thermoelastic-damping noise predictions of Braginsky, et al. [Phys. Lett. A
+264, 1(1999)] and Cerdonio, et al.[Phys. Rev. D 63, 082003 (2001)], which have
+been used to predict the astrophysical reach of advanced interferometric
+gravitational wave detectors.",0410028v1
+2004-10-28,Gravitational waves from neutron stars described by modern EOS,"The frequencies and damping times of neutron star (and quark star)
+oscillations have been computed using the most recent equations of state
+available in the literature. We find that some of the empirical relations that
+connect the frequencies and damping times of the modes to the mass and radius
+of the star, and that were previously derived in the literature need to be
+modified.",0410140v1
+2005-06-08,Resonant growth of stellar oscillations by incident gravitational waves,"Stellar oscillation under the combined influences of incident gravitational
+wave and radiation loss is studied in a simple toy model. The star is
+approximated as a uniform density ellipsoid in the Newtonian gravity including
+radiation damping through quadrupole formula. The time evolution of the
+oscillation is significantly controlled by the incident wave amplitude $h$,
+frequency $\nu$ and damping time $\tau$. If a combination $ h \nu \tau $
+exceeds a threshold value, which depends on the resonance mode, the resonant
+growth is realized.",0506047v1
+2006-11-28,Massive scalar field quasinormal modes of a Schwarzschild black hole surrounded by quintessence,"We present the quasinormal frequencies of the massive scalar field in the
+background of a Schwarzchild black hole surrounded by quintessence with the
+third-order WKB method. The mass of the scalar field $u$ plays an important
+role in studying the quasinormal frequencies, the real part of the frequencies
+increases linearly as mass $u$ increases, while the imaginary part in absolute
+value decreases linearly which leads to damping more slowly and the frequencies
+having a limited value. Moreover, owing to the presence of the quintessence,
+the massive scalar field damps more slowly.",0611146v2
+1992-09-24,Non-Abelian Boltzmann Equation for Mixing and Decoherence,"We consider particle oscillations and their damping in second-quantized form.
+We find that the damping or ""decoherence"" may be described by a Boltzmann-like
+collision integral with ""non-abelian blocking factors"" (fermions). Earlier
+results are generalized in that the momentum degrees of freedom are included
+and that the mixing equations become intrinsically non-linear at high
+densities.",9209276v1
+1993-06-03,The heavy fermion damping rate puzzle,": We examine again the problem of the damping rate of a moving heavy fermion
+in a hot plasma within the resummed perturbative theory of Pisarski and
+Braaten. The ansatz for its evaluation which relates it to the imaginary part
+of the fermion propagator pole in the framework of a self-consistent approach
+is critically analyzed. As already pointed out by various authors, the only way
+to define the rate is through additional implementation of magnetic screening.
+We show in detail how the ansatz works in this case and where we disagree with
+other authors. We conclude that the self-consistent approach is not
+satisfactory.",9306219v1
+1993-09-03,Damping Rate of a Fermion in a Medium,"We examine the relation between the damping rate of a massless, chiral
+fermion that propagates in a medium, and the rate $\Gamma$ of approach to
+equilibrium. It is proven that these quantities are equal, by showing that they
+are given by the same formula in terms of the imaginary part of the self-energy
+evaluated at the energy of the propagating fermion mode. This result is valid
+provided $\Gamma$ is defined by using the appropriate wave functions of the
+mode.",9309225v2
+1994-03-22,On the Damping Rate of a Fast Fermion in Hot QED,"The self-consistent determination of the damping rate of a fast moving
+fermion in a hot QED plasma is reexamined. We argue how a detailed
+investigation of the analytic properties of the retarded fermion Green's
+function motivated by the cutting rules at finite temperature may resolve
+ambiguities related to the proper definition of the mass-shell condition.",9403335v1
+1994-09-12,Fermion damping rate in a hot medium,"In principle every excitation acquires a finite lifetime in a hot system.
+This nonzero spectral width is calculated self-consistently for massive
+fermions coupled to massless scalar, vector and pseudoscalar bosons. It is
+shown that the self-consistent summation of the corresponding Fock diagram for
+fermions eliminates all infrared divergences although the bosons are not
+screened at all. Our solutions for the fermion damping rate are analytical in
+the coupling constant, but not analytical in the temperature parameter around
+T=0.",9409280v2
+1994-09-22,Lyapunov Exponent and Plasmon Damping Rate in Nonabelian Gauge Theories,"We explain why the maximal positive Lyapunov exponent of classical SU($N$)
+gauge theory coincides with (twice) the damping rate of a plasmon at rest in
+the leading order of thermal gauge theory. [This is a substantially revised and
+expanded version of the manuscript.]",9409392v2
+1994-12-20,Baryogenesis and damping in nonminimal electroweak models,"We study the effect of damping on the generation of baryon asymmetry of the
+Universe in the standard model of the eletroweak theory with simple extensions
+of the Higgs sector. The propagation of quarks of masses up to about 5 GeV are
+considered, taking into account their markedly different dispersion relations
+due to interaction with the hot electroweak plasma. It is argued that the
+contribution of the b quark can be comparable to that of the t quark calculated
+earlier.",9412330v1
+1998-10-07,Classical Kinetic Theory of Landau Damping for Self-interacting Scalar Fields in the Broken Phase,"The classical kinetic theory of one-component self-interacting scalar fields
+is formulated in the broken symmetry phase and applied to the phenomenon of
+Landau damping. The domain of validity of the classical approach is found by
+comparing with the result of a 1-loop quantum calculation.",9810278v2
+1999-08-02,Plasma wave instabilities induced by neutrinos,"Quantum field theory is applied to study the interaction of an electron
+plasma with an intense neutrino flux. A connection is established between the
+field theory results and classical kinetic theory. The dispersion relation and
+damping rate of the plasma longitudinal waves are derived in the presence of
+neutrinos. It is shown that Supernova neutrinos are never collimated enough to
+cause non-linear effects associated with a neutrino resonance. They only induce
+neutrino Landau damping, linearly proportional to the neutrino flux and
+$G_{\mathrm{F}}^{2}$.",9908206v2
+1999-09-27,Radiation Damping at a Bubble Wall,"The first order phase transition proceeds via nucleation and growth of true
+vacuum bubbles. When charged particles collide with the bubble they could
+radiate electromagnetic wave. We show that, due to an energy loss of the
+particles by the radiation, the damping pressure acting on the bubble wall
+depends on the velocity of the wall even in a thermal equilibrium state.",9909521v1
+1999-10-08,Lifetime of Collective Isospin Rotations of a Quantum Meson Field,"We calculate the lifetime of the collective isospin rotating solutions which
+have been found recently in the case a quantum N-component meson field with
+exact O(N) symmetry. For this purpose we take into account the small breaking
+of the O(N) symmetry associated to the non vanishing mass of the pion. This
+term induces a coupling between collective rotations and intrinsic meson
+excitations. We evaluate the associated damping time in the framework of linear
+response theory. We find damping times of the order of 100 fm/c, i.e.
+substantially longer than reaction times.",9910276v1
+2000-02-08,Finite pion width effects on the rho-meson and di-lepton spectra,"Within a field theoretical model where all damping width effects are treated
+self-consistently we study the changes of the spectral properties of rho-mesons
+due to the finite damping width of the pions in dense hadronic matter at finite
+temperature. The corresponding effects in the di-lepton yields are presented.
+Some problems concerning the self consistent treatment of vector or gauge
+bosons are discussed.",0002087v1
+2000-08-31,Damping of very soft moving quarks in high-temperature QCD,"We determine the analytic expression of the damping rates for very soft
+moving quarks in an expansion to second order in powers of their momentum in
+the context of QCD at high temperature. The calculation is performed using the
+hard-thermal-loop-summed perturbation scheme. We describe the range of validity
+of the expansion and make a comparison with other calculations, particularly
+those using a magnetic mass as a shield from infrared sensitivity. We discuss
+the possible occurrence of infrared divergences in our results and argue that
+they are due to magnetic sensitivity.",0008335v1
+2000-09-27,Damping of the HERA effect in DIS?,"The drastic rise of the proton structure function F_2(x,Q^2) when the
+Bj\""orken variable x decreases, seen at HERA for a large span of Q^2, negative
+values for the 4-momentum transfer, may be damped when Q^2 increases beyond
+several hundreds GeV^2. A new data analysis and a comparison with recent models
+for the proton structure function is proposed to discuss this phenomenon in
+terms of the derivative \partial ln F_2(x,Q^2)/\partial ln(1/x).",0009313v2
+2001-12-13,Time evolution in linear response: Boltzmann equations and beyond,"In this work a perturbative linear response analysis is performed for the
+time evolution of the quasi-conserved charge of a scalar field. One can find
+two regimes, one follows exponential damping, where the damping rate is shown
+to come from quantum Boltzmann equations. The other regime (coming from
+multiparticle cuts and products of them) decays as power law. The most
+important, non-oscillating contribution in our model comes from a 4-particle
+intermediate state and decays as 1/t^3. These results may have relevance for
+instance in the context of lepton number violation in the Early Universe.",0112188v1
+2002-04-26,Oscillation damping of chiral string loops,"Chiral cosmic string loop tends to the stationary (vorton) configuration due
+to the energy loss into the gravitational and electromagnetic radiation. We
+describe the asymptotic behaviour of near stationary chiral loops and their
+fading to vortons. General limits on the gravitational and electromagnetic
+energy losses by near stationary chiral loops are found. For these loops we
+estimate the oscillation damping time. We present solvable examples of
+gravitational radiation energy loss by some chiral loop configurations. The
+analytical dependence of string energy with time is found in the case of the
+chiral ring with small amplitude radial oscillations.",0204304v1
+2004-02-06,Critical Behavior of Damping Rate for Plasmon with Finite Momentum in φ^4 Theory,"Applying thermal renormalization group (TRG) equations to $\phi^4$ theory
+with spontaneous breaking symmetry, we investigate the critical behavior of the
+damping rate for the plasmons with finite momentum at the symmetry-restoring
+phase transition. From the TRG equation the IR cutoff provided by the external
+momentum leads to that the momentum-dependent coupling constant stops running
+in the critical region. As the result, the critical slowing down phenomenon
+reflecting the inherently IR effect doesn't take place at the critical point
+for the plasmon with finite external momentum.",0402069v2
+2005-11-22,Ultrasoft Quark Damping in Hot QCD,"We determine the quark damping rates in the context of next-to-leading order
+hard-thermal-loop summed perturbation of high-temperature QCD where weak
+coupling is assumed. The quarks are ultrasoft. Three types of divergent
+behavior are encountered: infrared, light-cone and at specific points
+determined by the gluon energies. The infrared divergence persists and is
+logarithmic whereas the two others are circumvented.",0511258v1
+2006-03-10,Numerical Approach to Multi Dimensional Phase Transitions,"We present an algorithm to analyze numerically the bounce solution of
+first-order phase transitions. Our approach is well suited to treat phase
+transitions with several fields. The algorithm consists of two parts. In the
+first part the bounce solution without damping is determined, in which case
+energy is conserved. In the second part the continuation to the physically
+relevant case with damping is performed. The presented approach is numerically
+stable and easily implemented.",0603081v2
+1994-06-22,Damped quantum harmonic oscillator: density operator and related quantities,"A closed expression for the density operator of the damped harmonic
+oscillator is extracted from the master equation based on the Lindblad theory
+for open quantum systems. The entropy and effective temperature of the system
+are subsequently calculated and their temporal behaviour is surveyed by showing
+how these quantities relax to their equilibrium values. The entropy for a state
+characterized by a Wigner distribution function which is Gaussian in form is
+found to depend only on the variance of the distribution function.",9406142v1
+1997-05-09,Radiation Damping of a BPS Monopole; an Implication to S-duality,"The radiation reaction of a BPS monopole in the presence of incident
+electromagnetic waves as well as massless Higgs waves is analyzed classically.
+The reactive forces are compared to those of $W$ boson that is interpreted as a
+dual partner of the BPS monopole. It is shown that the damping of acceleration
+is dual to each other, while in the case of finite size effects the duality is
+broken explicitly. Their implications on the duality are discussed.",9705059v2
+1997-07-02,The Asymptotic Method Developed from Weak Turbulent Theory and the Nonlinear Permeability and Damping Rate in QGP,"With asymptotic method developed from weak turbulent theory, the kinetic
+equations for QGP are expanded in fluctuation field potential $A^T_\mu $.
+Considering the second-order and third-order currents, we derive the nonlinear
+permeability tensor function from Yang-Mills field equation, and find that the
+third-order current is more important in turbulent theory. The nonlinear
+permeability formulae for longitudinal color oscillations show that the
+non-Abelian effects are more important than the Abelian-like effects. To
+compare with other works, we give the numerical result of the damping rate for
+the modes with zero wave vector.",9707052v1
+2005-04-07,Continuous area spectrum in regular black hole,"We investigate highly damped quasinormal modes of regular black hole coupled
+to nonlinear electrodynamics. Using the WKB approximation combined with
+complex-integration technique, we show that the real part of the frequency
+disappears in the highly damped limit. If we use the Bohr's correspondence
+principle, the area spectrum of this black hole is continuous. We discuss its
+implication in the loop quantum gravity.",0504059v2
+2005-05-16,Supersymmetrization of the Radiation Damping,"We construct a supersymmetrized version of the model to the radiation damping
+\cite{03} introduced by the present authors \cite{ACWF}. We dicuss its
+symmetries and the corresponding conserved Noether charges. It is shown this
+supersymmetric version provides a supersymmetric generalization of the Galilei
+algebra obtained in \cite{ACWF}. We have shown that the supersymmetric action
+can be splited into dynamically independent external and internal sectors.",0505142v1
+1999-08-16,Topological Entropy and epsilon-Entropy for Damped Hyperbolic Equations,"We study damped hyperbolic equations on the infinite line. We show that on
+the global attracting set $G$ the $\epsilon$-entropy (per unit length) exists
+in the topology of $W^{1,\infty}$. We also show that the topological entropy
+per unit length of $G$ exists. These results are shown using two main
+techniques: Bounds in bounded domains in position space and for large momenta,
+and a novel submultiplicativity argument in $W^{1,\infty}$.",9908080v1
+2003-11-28,Uniform stability of damped nonlinear vibrations of an elastic string,"Here we are concerned about uniform stability of damped nonlinear transverse
+vibrations of an elastic string fixed at its two ends. The vibrations governed
+by nonlinear integro-differential equation of Kirchoff type, is shown to
+possess energy uniformly bounded by exponentially decaying function of time.
+The result is achieved by considering an energy-like Lyapunov functional for
+the system.",0311527v1
+2005-07-06,On stability and stabilization of elastic systems by time-variant feedback,"We study a class of elastic systems described by a (hyperbolic) partial
+differential equation. Our working example is the equation of a vibrating
+string subject to linear disturbance. The main goal is to establish conditions
+for stabilization and asymptotic stabilization by applying a fast oscillating
+control to the string. In the first situation studied we assume that system is
+subject to a damping force; next we consider the system without damping. We
+extend the tools of high-order averaging and of chronological calculus for
+studying stability of this distributed parameter system.",0507123v1
+2006-01-13,Attractors for damped hyperbolic equations on arbitrary unbounded domains,"We prove existence of global attractors for damped hyperbolic equations of
+the form $$\aligned \eps u_{tt}+\alpha(x) u_t+\beta(x)u- \sum_{ij}(a_{ij}(x)
+u_{x_j})_{x_i}&=f(x,u),\quad x\in \Omega, t\in[0,\infty[, u(x,t)&=0,\quad x\in
+\partial \Omega, t\in[,\infty[.\endaligned$$ on an unbounded domain $\Omega$,
+without smoothness assumptions on $\beta(\cdot)$, $a_{ij}(\cdot)$, $f(\cdot,u)$
+and $\partial\Omega$, and $f(x,\cdot)$ having critical or subcritical growth.",0601319v3
+2007-02-07,Finite time blow-up results for the damped wave equations with arbitrary initial energy in an inhomogeneous medium,"In this paper we consider the long time behavior of solutions of the initial
+value problem for the damped wave equation of the form \begin{eqnarray*}
+u_{tt}-\rho(x)^{-1}\Delta u+u_t+m^2u=f(u) \end{eqnarray*} with some $\rho(x)$
+and $f(u)$ on the whole space $\R^n$ ($n\geq 3$).
+  For the low initial energy case, which is the non-positive initial energy,
+based on concavity argument we prove the blow up result. As for the high
+initial energy case, we give out sufficient conditions of the initial datum
+such that the corresponding solution blows up in finite time.",0702190v1
+2007-03-09,Analyticity and Riesz basis property of semigroups associated to damped vibrations,"Second order equations of the form $z'' + A_0 z + D z'=0$ in an abstract
+Hilbert space are considered. Such equations are often used as a model for
+transverse motions of thin beams in the presence of damping. We derive various
+properties of the operator matrix $A$ associated with the second order problem
+above. We develop sufficient conditions for analyticity of the associated
+semigroup and for the existence of a Riesz basis consisting of eigenvectors and
+associated vectors of $A$ in the phase space.",0703247v1
+2007-03-21,Existence and asymptotic behavior of $C^1$ solutions to the multidimensional compressible Euler equations with damping,"In this paper, the existence and asymptotic behavior of $C^1$ solutions to
+the multidimensional compressible Euler equations with damping on the framework
+of Besov space are considered. We weaken the regularity requirement of the
+initial data, and improve the well-posedness results of Sideris-Thomases-Wang
+(Comm.P.D.E. 28 (2003) 953). The global existence lies on a crucial a-priori
+estimate which is proved by the spectral localization method. The main analytic
+tools are the Littlewood-Paley decomposition and Bony's para-product formula.",0703621v1
+2000-12-22,The Vlasov-Poisson system with radiation damping,"We set up and analyze a model of radiation damping within the framework of
+continuum mechanics, inspired by a model of post-Newtonian hydrodynamics due to
+Blanchet, Damour and Schaefer. In order to simplify the problem as much as
+possible we replace the gravitational field by the electromagnetic field and
+the fluid by kinetic theory. We prove that the resulting system has a
+well-posed Cauchy problem globally in time for general initial data and in all
+solutions the fields decay to zero at late times. In particular, this means
+that the model is free from the runaway solutions which frequently occur in
+descriptions of radiation reaction.",0012041v1
+2003-01-17,Quantum mechanics of damped systems,"We show that the quantization of a simple damped system leads to a
+self-adjoint Hamiltonian with a family of complex generalized eigenvalues. It
+turns out that they correspond to the poles of energy eigenvectors when
+continued to the complex energy plane. Therefore, the corresponding generalized
+eigenvectors may be interpreted as resonant states. We show that resonant
+states are responsible for the irreversible quantum dynamics of our simple
+model.",0301024v3
+2003-07-23,Quantum Mechanics of Damped Systems II. Damping and Parabolic Potential Barrier,"We investigate the resonant states for the parabolic potential barrier known
+also as inverted or reversed oscillator. They correspond to the poles of
+meromorphic continuation of the resolvent operator to the complex energy plane.
+As a byproduct we establish an interesting relation between parabolic cylinder
+functions (representing energy eigenfunctions of our system) and a class of
+Gel'fand distributions used in our recent paper.",0307047v1
+2001-07-02,Pattern formation and localization in the forced-damped FPU lattice,"We study spatial pattern formation and energy localization in the dynamics of
+an anharmonic chain with quadratic and quartic intersite potential subject to
+an optical, sinusoidally oscillating field and a weak damping. The
+zone-boundary mode is stable and locked to the driving field below a critical
+forcing that we determine analytically using an approximate model which
+describes mode interactions. Above such a forcing, a standing modulated wave
+forms for driving frequencies below the band-edge, while a ``multibreather''
+state develops at higher frequencies. Of the former, we give an explicit
+approximate analytical expression which compares well with numerical data. At
+higher forcing space-time chaotic patterns are observed.",0107002v1
+2003-06-16,On the influence of noise on chaos in nearly Hamiltonian systems,"The simultaneous influence of small damping and white noise on Hamiltonian
+systems with chaotic motion is studied on the model of periodically kicked
+rotor. In the region of parameters where damping alone turns the motion into
+regular, the level of noise that can restore the chaos is studied. This
+restoration is created by two mechanisms: by fluctuation induced transfer of
+the phase trajectory to domains of local instability, that can be described by
+the averaging of the local instability index, and by destabilization of motion
+within the islands of stability by fluctuation induced parametric modulation of
+the stability matrix, that can be described by the methods developed in the
+theory of Anderson localization in one-dimensional systems.",0306024v1
+2003-07-30,Faraday Wave Pattern Selection Via Multi-Frequency Forcing,"We use symmetry considerations to investigate how damped modes affect pattern
+selection in multi-frequency forced Faraday waves. We classify and tabulate the
+most important damped modes and determine how the corresponding resonant triad
+interactions depend on the forcing parameters. The relative phase of the
+forcing terms may be used to enhance or suppress the nonlinear interactions. We
+compare our predictions with numerical results and discuss their implications
+for recent experiments. Our results suggest how to design multi-frequency
+forcing functions that favor chosen patterns in the lab.",0307056v1
+2004-10-21,Stabilization mechanism for two-dimensional solitons in nonlinear parametric resonance,"We consider a simple model system supporting stable solitons in two
+dimensions. The system is the parametrically driven damped nonlinear
+Schr\""odinger equation, and the soliton stabilises for sufficiently strong
+damping. The purpose of this note is to elucidate the stabilisation mechanism;
+we do this by reducing the partial differential equation to a
+finite-dimensional dynamical system. Our conclusion is that the negative
+feedback loop occurs via the enslaving of the soliton's phase, locked to the
+driver, to its amplitude and width.",0410044v1
+2006-01-14,Vibration of the Duffing Oscillator: Effect of Fractional Damping,"We have applied the Melnikov criterion to examine a global homoclinic
+bifurcation and transition to chaos in a case of the Duffing system with
+nonlinear fractional damping and external excitation.
+  Using perturbation methods we have found a critical forcing amplitude above
+which the system may behave chaotically.
+  The results have been verified by numerical simulations using standard
+nonlinear tools as
+  Poincare maps and a Lyapunov exponent. Above the critical Melnikov amplitude
+$\mu_c$, which is the sufficient condition of a global homoclinic bifurcation,
+we have observed the region with a transient chaotic motion.",0601033v1
+2006-11-02,Solitons in strongly driven discrete nonlinear Schrödinger-type models,"Discrete solitons in the Ablowitz-Ladik (AL) and discrete nonlinear
+Schr\""odinger (DNLS) equations with damping and strong rapid drive are
+investigated. The averaged equations have the forms of the parametric AL and
+DNLS equations. A new type of parametric bright discrete soliton and cnoidal
+waves are found and the stability properties are analyzed. The analytical
+predictions of the perturbed inverse scattering transform are confirmed by the
+numerical simulations of the AL and DNLS equations with rapidly varying drive
+and damping.",0611004v1
+2006-11-26,On the Lagrangian and Hamiltonian description of the damped linear harmonic oscillator,"Using the modified Prelle- Singer approach, we point out that explicit time
+independent first integrals can be identified for the damped linear harmonic
+oscillator in different parameter regimes. Using these constants of motion, an
+appropriate Lagrangian and Hamiltonian formalism is developed and the resultant
+canonical equations are shown to lead to the standard dynamical description.
+Suitable canonical transformations to standard Hamiltonian forms are also
+obtained. It is also shown that a possible quantum mechanical description can
+be developed either in the coordinate or momentum representations using the
+Hamiltonian forms.",0611048v1
+1992-12-14,Microscopic Origin of Quantum Chaos in Rotational Damping,"The rotational spectrum of $^{168}$Yb is calculated diagonalizing different
+effective interactions within the basis of unperturbed rotational bands
+provided by the cranked shell model. A transition between order and chaos
+taking place in the energy region between 1 and 2 MeV above the yrast line is
+observed, associated with the onset of rotational damping. It can be related to
+the higher multipole components of the force acting among the unperturbed
+rotational bands.",9212005v1
+1996-12-17,Damping mechanisms of the Delta resonance in nuclei,"The damping mechanisms of the Delta(1232) resonance in nuclei are studied by
+analyzing the quasi-free decay reactions 12C(pi+,pi+ p)11B and 12C(3He,t pi+
+p)11B and the 2p emission reactions 12C(pi+,pp)10B and 12C(3He,t pp)10B. The
+coincidence cross sections are calculated within the framework of the
+isobar-hole model. It is found that the 2p emission process induced by the
+decay of the Delta resonance in the nucleus can be consistently described by a
+pi+rho+g' model for the Delta+N -> N+N decay interaction.",9612046v1
+1997-11-08,Cooperative damping mechanism of the resonance in the nuclear photoabsorption,"We propose a resonance damping mechanism to explain the disappearance of the
+peaks around the position of the resonances higher than the $\Delta$ resonance
+in the nuclear photoabsorption. This phenomenon is understood by taking into
+account the cooperative effect of the collision broadening of $\Delta$ and
+$N^{*}$, the pion distortion and the interference in the two-pion
+photoproduction processes in the nuclear medium.",9711017v4
+1998-05-27,Collisional Damping of Nuclear Collective Vibrations in a Non-Markovian Transport Approach,"A detailed derivation of the collisional widths of collective vibrations is
+presented in both quantal and semi-classical frameworks by considering the
+linearized limits of the extended TDHF and the BUU model with a non-Markovian
+binary collision term. Damping widths of giant dipole and giant quadrupole
+excitations are calculated by employing an effective Skyrme force, and the
+results are compared with GDR measurements in Lead and Tin nuclei at finite
+temperature.",9805050v1
+1999-07-06,Probing the width of compound states with rotational gamma rays,"The intrinsic width of (multiparticle-multihole) compound states is an
+elusive quantity, of difficult direct access, as it is masked by damping
+mechanisms which control the collective response of nuclei. Through microscopic
+cranked shell model calculations, it is found that the strength function
+associated with two-dimensional gamma-coincidence spectra arising from
+rotational transitions between states lying at energies >1 MeV above the yrast
+line, exhibits a two-component structure controlled by the rotational (wide
+component) and compound (narrow component) damping width. This last component
+is found to be directly related to the width of the multiparticle-multihole
+autocorrelation function.",9907016v1
+1999-07-09,Color plasma oscillation in strangelets,"The dispersion relation and damping rate of longitudinal color plasmons in
+finite strange quark matter (strangelets) are evaluated in the limits of weak
+coupling, low temperature, and long wavelength. The property of the QCD vacuum
+surrounding a strangelet makes the frequency of the plasmons nearly the same as
+the color plasma frequency of bulk matter. The plasmons are damped by their
+coupling with individual excitations of particle-hole pairs of quarks, of which
+the energy levels are discretized by the boundary. For strangelets of
+macroscopic size, the lifetime of the plasmons is found to be proportional to
+the size, as in the case of the usual plasma oscillations in metal
+nanoparticles.",9907039v1
+1999-09-21,On the Collisional Damping of Giant Dipole Resonance,"Collisional damping widths of giant dipole excitations are calculated in
+Thomas-Fermi approximation by employing the microscopic in-medium
+cross-sections of Li and Machleidt and the phenomenological Gogny force. The
+results obtained in both calculations compare well, but account for about
+25-35% of the observed widths in $^{120}Sn$ and $^{208}Pb$ at finite
+temperatures.",9909057v1
+2000-01-09,Strongly damped nuclear collisions: zero or first sound ?,"The relaxation of the collective quadrupole motion in the initial stage of a
+central heavy ion collision at beam energies $E_{lab}=5\div20$ AMeV is studied
+within a microscopic kinetic transport model. The damping rate is shown to be a
+non-monotonic function of E_{lab} for a given pair of colliding nuclei. This
+fact is interpreted as a manifestation of the zero-to-first sound transition in
+a finite nuclear system.",0001016v1
+2002-11-18,Collision damping in the pi 3He -> d'N reaction near the threshold,"We present a simple quantum mechanical model exploiting the optical potential
+approach for the description of collision damping in the reaction pi 3He -> d'N
+near the threshold, which recently has been measured at TRIUMF. The influence
+of the open d'N -> NNN channel is taken into account. It leads to a suppression
+factor of about ten in the d' survival probability. Applications of the method
+to other reactions are outlined.",0211050v1
+2003-03-14,Pion damping width from SU(2) x SU(2) NJL model,"Within the framework of the NJL model, we investigate the modification of the
+pion damping width in a hot pion gas for temperatures ranging from 0 to 180
+MeV. The pion is found to broaden noticeably at T > 60 MeV. Near the chiral
+phase transition T ~ 180 MeV, the pion width is saturated and amounts to 70
+MeV. The main contribution to the width comes from pion-pion collisions. Other
+contributions are found negligibly small.",0303034v1
+2004-06-09,Damped collective motion of isolated many body systems within a variational approach to functional integrals,"Two improvements with respect to previous formulations are presented for the
+calculation of the partition function $\mathcal{Z}$ of small, isolated and
+interacting many body systems. By including anharmonicities and employing a
+variational approach quantum effects can be treated even at very low
+temperatures. A method is proposed of how to include collisional damping.
+Finally, our approach is applied to the calculation of the decay rate of
+metastable systems.",0406025v1
+2004-07-26,Damped collective motion of many body systems: A variational approach to the quantal decay rate,"We address the problem of collective motion across a barrier like encountered
+in fission. A formula for the quantal decay rate is derived which bases on a
+recently developed variational approach for functional integrals. This formula
+can be applied to low temperatures that have not been accessible within the
+former PSPA type approach. To account for damping of collective motion one
+particle Green functions are dressed with appropriate self-energies.",0407092v2
+1997-11-15,Fluctuational phase-flip transitions in parametrically pumped oscillators,"We analyze the rates of noise-induced transitions between period-two
+attractors. The model investigated is an underdamped oscillator parametrically
+driven by a field at nearly twice the oscillator eigenfrequency. The activation
+energy of the transitions is analyzed as a function of the frequency detuning
+and field amplitude scaled by the damping and nonlinearity parameters of the
+oscillator. The parameter ranges where the system is bi- and tristable are
+investigated. Explicit results are obtained in the limit of small damping (or
+strong driving), and near bifurcation points.",9711014v1
+1999-05-31,Collisionless Damping of Low-Frequency Magnetosonic Pulses in a Two-Ion-Species Plasma,"Low-frequency mangnetosonic pulses in a two-ion-species plasma are studied
+theoretically and by simulation with a one-dimensional electromagnetic
+simulation code based on a three-fluid model, with particular attention to the
+dynamics of minority heavy ions. It is found that heavy ions can gain some
+energy from the pulses. Because of this energy transfer, the pulses are damped
+even if the plasma is collisionless and pulse propagation is perpendicular to
+the magnetic field.",9905059v1
+2000-10-17,Bunch Length Measurements at the ATF Damping Ring in April 2000,"This report presents bunch length and energy spread measurements performed in
+April 2000 at the ATF Damping Ring, at KEK. Measurements were performed with
+the beam on and then off the linear (difference) coupling resonance. Due to
+strong intra-beam scattering in the ATF ring, the results depended strongly on
+the coupling.",0010043v1
+2000-12-21,Phase transition in the collisionless regime for wave-particle interaction,"Gibbs statistical mechanics is derived for the Hamiltonian system coupling
+self-consistently a wave to N particles. This identifies Landau damping with a
+regime where a second order phase transition occurs. For nonequilibrium initial
+data with warm particles, a critical initial wave intensity is found: above it,
+thermodynamics predicts a finite wave amplitude in the limit of infinite N;
+below it, the equilibrium amplitude vanishes. Simulations support these
+predictions providing new insight on the long-time nonlinear fate of the wave
+due to Landau damping in plasmas.",0012053v1
+2001-09-25,Creep and Mechanical Oscillator Damping,"Although ""friction"" is included in many models of oscillator damping,
+including viscous ones applied to the pendulum; they ""miss the mark"" with
+regard to a conceptual understanding of the mechanisms responsible for energy
+loss. The theory of the present paper corrects some of these misunderstandings
+by considering the influence of internal friction which derives from the
+structural members of the oscillator through secondary rather than primary
+creep. The simple model properly describes the variation of Q with frequency.",0109067v1
+2001-11-06,Electromagnetic induction and damping - quantitative experiments using PC interface,"A bar magnet, attached to an oscillating system, passes through a coil
+periodically, generating a series of emf pulses. A novel method is described
+for the quantitative verification of Faraday's law which eliminates all errors
+associated with angular measurements, thereby revealing delicate features of
+the underlying mechanics. When electromagnetic damping is activated by
+short-circuiting the coil, a distinctly linear decay of oscillation amplitude
+is surprisingly observed. A quantitative analysis reveals an interesting
+interplay of the electromagnetic and mechanical time scales.",0111016v1
+2003-08-31,Effects of Bulk Viscosity in Non-linear Bubble Dynamics,"The non-linear bubble dynamics equations in a compressible liquid have been
+modified considering the effects of compressibility of both the liquid and the
+gas at the bubble interface. A new bubble boundary equation has been derived,
+which includes a new term resulted from the liquid bulk viscosity effects. The
+influence of this term has been numerically investigated considering the
+effects of water vapor and chemical reactions on the bubble evolution. The
+results clearly indicate that the new term has an important damping role at the
+collapse, so that its consideration decreases the amplitude of the bubble
+rebounds after the collapse. This damping feature is more remarkable for higher
+deriving pressures.",0309012v1
+2004-04-30,"On violation of the Robinson's damping criterion and enhanced cooling of ion, electron and muon beams in storage rings","Limits of applicability of the Robinson's damping criterion and the problem
+of enhanced cooling of particle beams in storage rings beyond the criterion are
+discussed.",0404142v6
+2004-12-28,"Electron Bernstein waves in spherical tokamak plasmas with ""magnetic wells""","In addition to traditional regimes with monotonously increasing magnetic
+field, regimes with ""magnetic wells"" also occur in spherical tokamaks (STs).
+The magnetic field profile inversion modifies significantly the whole picture
+of the wave propagation and damping. Since the magnetic wells may become quite
+common with further improvement of ST performance, analysis of such
+configurations is of interest for assessment of EBW plasma heating an CD
+perspectives. In this paper the basic features of the EBWs propagation and
+damping for the second cyclotron harmonic in a slab model are considered.",0412173v1
+2005-02-10,Modulational instabilities in Josephson oscillations of elongated coupled condensates,"We study the Josephson oscillations of two coupled elongated condensates.
+Linearized calculations show that the oscillating mode uniform over the length
+of the condensates (uniform Josephson mode) is unstable : modes of non zero
+longitudinal momentum grow exponentially. In the limit of strong atom
+interactions, we give scaling laws for the instability time constant and
+unstable wave vectors. Beyond the linearized approach, numerical calculations
+show a damped recurrence behavior : the energy in the Josephson mode presents
+damped oscillations. Finally, we derive conditions on the confinement of the
+condensates to prevent instabilities.",0502050v3
+2005-08-16,Creep-Enhanced Low-Frequency Sensitivity of Seismometers,"The frequency response of a seismometer is typically assumed to be the
+textbook case of a viscous damped, simple harmonic oscillator. Real mechanical
+oscillators are not ideal, and the damping at low frequencies, due to internal
+friction, is presently too poorly understood to describe from first principles.
+Even if the low-level motions were smooth (which they are not), the mean
+position of a seismic mass changes because of creep and creep recovery. This
+article shows that secondary creep can actually serve to increase the
+sensitivity of a seismometer at low frequencies.",0508105v1
+2006-06-22,Looking for a time independent Hamiltonian of a dynamical system,"In this paper we introduce a method for finding a time independent
+Hamiltonian of a given dynamical system by canonoid transformation. We also
+find a condition that the system should satisfy to have an equivalent time
+independent formulation. We study the example of damped oscillator and give the
+new time independent Hamiltonian for it, which has the property of tending to
+the standard Hamiltonian of the harmonic oscillator as damping goes to zero.",0606197v2
+1996-02-27,Effects of Loss and Decoherence on a Simple Quantum Computer,"We investigate the impact of loss (amplitude damping) and decoherence (phase
+damping) on the performance of a simple quantum computer which solves the
+one-bit Deutsch problem. The components of this machine are beamsplitters and
+nonlinear optical Kerr cells, but errors primarily originate from the latter.
+We develop models to describe the effect of these errors on a quantum optical
+Fredkin gate. The results are used to analyze possible error correction
+strategies in a complete quantum computer. We find that errors due to loss can
+be avoided perfectly by appropriate design techniques, while decoherence can be
+partially dealt with using projective error correction.",9602018v1
+1996-11-25,The Quantum state diffusion model and the driven damped nonlinear oscillator,"We consider a driven damped anharmonic oscillator which classically leads to
+a bistable steady state and to hysteresis. The quantum counterpart for this
+system has an exact analytical solution in the steady state which does not
+display any bistability or hysteresis. We use quantum state diffusion theory to
+describe this system and to provide a new perspective on the lack of hysteresis
+in the quantum regime so as to study in detail the quantum to classical
+transition. The analysis is also relevant to measurements of a single
+periodically driven electron in a Penning trap where hysteresis has been
+observed.",9611044v1
+1997-12-02,Prevention of dissipation with two particles,"An error prevention procedure based on two-particle encoding is proposed for
+protecting an arbitrary unknown quantum state from dissipation, such as phase
+damping and amplitude damping. The schemes, which exhibits manifestation of the
+quantum Zeno effect, is effective whether quantum bits are decohered
+independently or cooperatively. We derive the working condition of the scheme
+and argue that this procedure has feasible practical implementation.",9712005v1
+1998-02-23,Caldirola-Kanai Oscillator in Classical Formulation of Quantum Mechanics,"The quadrature distribution for the quantum damped oscillator is introduced
+in the framework of the formulation of quantum mechanics based on the
+tomography scheme. The probability distribution for the coherent and Fock
+states of the damped oscillator is expressed explicitly in terms of Gaussian
+and Hermite polynomials, correspondingly.",9802057v1
+1999-03-22,Decoherence - Fluctuation Relation and Measurement Noise,"We discuss fluctuations in the measurement process and how these fluctuations
+are related to the dissipational parameter characterising quantum damping or
+decoherence. On the example of the measuring current of the variable-barrier or
+QPC problem we show there is an extra noise or fluctuation connected with the
+possible different outcomes of a measurement. This noise has an enhanced short
+time component which could be interpreted as due to ``telegraph noise'' or
+``wavefunction collapses''. Furthermore the parameter giving the the strength
+of this noise is related to the parameter giving the rate of damping or
+decoherence.",9903072v1
+1999-07-27,Nonclassical correlations in damped N-solitons,"The quantum statistics of damped higher-order optical solitons are analyzed
+numerically, using cumulant-expansion techniques in Gaussian approximation. A
+detailed analysis of nonclassical properties in both the time and the frequency
+domain is given, with special emphasis on the role of absorption. Highly
+nonclassical broadband spectral correlation is predicted.",9907090v2
+2001-01-08,Cavity-damping-induced transitions in a driven atom-cavity system,"We investigate the fluorescence spectrum of a two-level atom in a cavity when
+the atom is driven by a classical field. We show that forbidden dipole
+transitions in the Jaynes-Cummings Ladder structure are induced in the presence
+of the cavity damping, which deteriorates the degree of otherwise perfect
+destructive interference among the transition channels. With the larger cavity
+decay, these transitions are more enhanced.",0101036v1
+2001-06-09,Squeezing enhancement by damping in a driven atom-cavity system,"In a driven atom-cavity coupled system in which the two-level atom is driven
+by a classical field, the cavity mode which should be in a coherent state in
+the absence of its reservoir, can be squeezed by coupling to its reservoir. The
+squeezing effect is enhanced as the damping rate of the cavity is increased to
+some extent.",0106054v1
+2001-08-01,Decoherence-induced wave packet splitting,"We provide an intuitive interpretation of the optical Stern-Gerlach effect
+(OSGE) in the dressed-state point of view. We also analyze the effect of atomic
+damping in an experiment on the OSGE. We show that the atomic damping also
+causes the wave packet splitting, in a non-mechanical fashion, as opposed to
+the coherent process that is mechanical.",0108005v1
+2001-08-11,A Canonical Approach to the Quantization of the Damped Harmonic Oscillator,"We provide a new canonical approach for studying the quantum mechanical
+damped harmonic oscillator based on the doubling of degrees of freedom
+approach. Explicit expressions for Lagrangians of the elementary modes of the
+problem, characterising both forward and backward time propagations are given.
+  A Hamiltonian analysis, showing the equivalence with the Lagrangian approach,
+is also done. Based on this Hamiltonian analysis, the quantization of the model
+is discussed.",0108055v2
+2002-05-09,Implementation of quantum maps by programmable quantum processors,"A quantum processor is a device with a data register and a program register.
+The input to the program register determines the operation, which is a
+completely positive linear map, that will be performed on the state in the data
+register. We develop a mathematical description for these devices, and apply it
+to several different examples of processors. The problem of finding a processor
+that will be able to implement a given set of mappings is also examined, and it
+is shown that while it is possible to design a finite processor to realize the
+phase-damping channel, it is not possible to do so for the amplitude-damping
+channel.",0205050v1
+2002-08-28,Damped Quantum Interference using Stochastic Calculus,"It is shown how the phase-damping master equation, either in Markovian and
+nonMarkovian regimes, can be obtained as an averaged random unitary evolution.
+This, apart from offering a common mathematical setup for both regimes, enables
+us to solve this equation in a straightforward manner just by solving the
+Schrodinger equation and taking the stochastic expectation value of its
+solutions after an adequate modification. Using the linear entropy as a figure
+of merit (basically the loss of quantum coherence) the distinction of four
+kinds of environments is suggested.",0208176v1
+2002-10-31,Quantum Markov Channels for Qubits,"We examine stochastic maps in the context of quantum optics. Making use of
+the master equation, the damping basis, and the Bloch picture we calculate a
+non-unital, completely positive, trace-preserving map with unequal damping
+eigenvalues. This results in what we call the squeezed vacuum channel. A
+geometrical picture of the effect of stochastic noise on the set of pure state
+qubit density operators is provided. Finally, we study the capacity of the
+squeezed vacuum channel to transmit quantum information and to distribute EPR
+states.",0211001v1
+2003-01-17,Concurrence and foliations induced by some 1-qubit channels,"We start with a short introduction to the roof concept. An elementary
+discussion of phase-damping channels shows the role of anti-linear operators in
+representing their concurrence. A general expression for some concurrences is
+derived. We apply it to 1-qubit channels of length two, getting induced
+foliations of the state space, the optimal decompositions, and the entropy of a
+state with respect to these channels. For amplitude-damping channels one
+obtains an expression for the Holevo capacity allowing for easy numerical
+calculations.",0301088v1
+2003-05-19,Statistical Effects in the Multistream Model for Quantum Plasmas,"A statistical multistream description of quantum plasmas is formulated, using
+the Wigner-Poisson system as dynamical equations. A linear stability analysis
+of this system is carried out, and it is shown that a Landau-like damping of
+plane wave perturbations occurs due to the broadening of the background Wigner
+function that arises as a consequence of statistical variations of the wave
+function phase. The Landau-like damping is shown to suppress instabilities of
+the one- and two-stream type.",0305102v1
+2003-06-28,Misbelief and misunderstandings on the non--Markovian dynamics of a damped harmonic oscillator,"We use the exact solution for the damped harmonic oscillator to discuss some
+relevant aspects of its open dynamics often mislead or misunderstood. We
+compare two different approximations both referred to as Rotating Wave
+Approximation. Using a specific example, we clarify some issues related to
+non--Markovian dynamics, non--Lindblad type dynamics, and positivity of the
+density matrix.",0306193v3
+2003-11-26,Effective damping in the Raman cooling of trapped ions,"We present a method of treating the interaction of a single three-level ion
+with two laser beams. The idea is to apply a unitary transformation such that
+the exact transformed Hamiltonian has one of the three levels decoupled for all
+values of the detunings. When one takes into account damping, the evolution of
+the system is governed by a master equation usually obtained via adiabatic
+approximation under the assumption of far-detuned lasers. To go around the
+drawbacks of this technique, we use the same unitary transformation to get an
+effective master equation.",0311183v1
+2004-06-20,Entanglement-assisted classical information capacity of the amplitude damping channel,"In this paper, we calculate the entanglement-assisted classical information
+capacity of amplitude damping channel and compare it with the particular mutual
+information which is considered as the entanglement-assisted classical
+information capacity of this channel in Ref. 6. It is shown that the difference
+between them is very small. In addition, we point out that using partial
+symmetry and concavity of mutual information derived from dense coding scheme
+one can simplify the calculation of entanglement-assisted classical information
+capacities for non-unitary-covariant quantum noisy channels.",0406140v1
+2004-08-13,Decoherence versus Dynamical Casimir Effect,"By means of two simple examples: phase and amplitude damping, the impact of
+decoherence on the dynamical Casimir effect is investigated. Even without
+dissipating energy (i.e., pure phase damping), the amount of created particles
+can be diminished significantly via the coupling to the environment (reservoir
+theory) inducing decoherence. For a simple microscopic model, it is
+demonstrated that spontaneous decays within the medium generate those problems
+-- Rabi oscillations are far more advantageous in that respect. These findings
+are particularly relevant in view of a recently proposed experimental
+verification of the dynamical Casimir effect. PACS: 42.50.Lc, 03.65.Yz,
+03.70.+k, 42.50.Dv.",0408087v2
+2004-10-11,Quantizing the damped harmonic oscillator,"We consider the Fermi quantization of the classical damped harmonic
+oscillator (dho). In past work on the subject, authors double the phase space
+of the dho in order to close the system at each moment in time. For an
+infinite-dimensional phase space, this method requires one to construct a
+representation of the CAR algebra for each time. We show that unitary dilation
+of the contraction semigroup governing the dynamics of the system is a logical
+extension of the doubling procedure, and it allows one to avoid the
+mathematical difficulties encountered with the previous method.",0410078v1
+2004-11-18,Drastic effects of damping mechanisms on the third-order optical nonlinearity,"We have investigated the optical response of superradiant atoms, which
+undergoes three different damping mechanisms: radiative dissipation
+($\gamma_r$), dephasing ($\gamma_d$), and nonradiative dissipation
+($\gamma_n$). Whereas the roles of $\gamma_d$ and $\gamma_n$ are equivalent in
+the linear susceptibility, the third-order nonlinear susceptibility drastically
+depends on the ratio of $\gamma_d$ and $\gamma_n$: When $\gamma_d \ll
+\gamma_n$, the third-order susceptibility is essentially that of a single atom.
+Contrarily, in the opposite case of $\gamma_d \gg \gamma_n$, the third-order
+susceptibility suffers the size-enhancement effect and becomes proportional to
+the system size.",0411129v1
+2005-01-19,Stabilizing an atom laser using spatially selective pumping and feedback,"We perform a comprehensive study of stability of a pumped atom laser in the
+presence of pumping, damping and outcoupling. We also introduce a realistic
+feedback scheme to improve stability by extracting energy from the condensate
+and determine its effectiveness. We find that while the feedback scheme is
+highly efficient in reducing condensate fluctuations, it usually does not alter
+the stability class of a particular set of pumping, damping and outcoupling
+parameters.",0501101v1
+2005-06-11,Quantum damped oscillator II: Bateman's Hamiltonian vs. 2D Parabolic Potential Barrier,"We show that quantum Bateman's system which arises in the quantization of a
+damped harmonic oscillator is equivalent to a quantum problem with 2D parabolic
+potential barrier known also as 2D inverted isotropic oscillator. It turns out
+that this system displays the family of complex eigenvalues corresponding to
+the poles of analytical continuation of the resolvent operator to the complex
+energy plane. It is shown that this representation is more suitable than the
+hyperbolic one used recently by Blasone and Jizba.",0506091v1
+2005-06-27,Entanglement of pair cat states and teleportation,"The entanglement of pair cat states in the phase damping channel is studied
+by employing the relative entropy of entanglement. It is shown that the pair
+cat states can always be distillable in the phase damping channel. Furthermore,
+we analyze the fidelity of teleportation for the pair cat states by using joint
+measurements of the photon-number sum and phase difference.",0506217v1
+2005-07-21,Entanglement versus mixedness for coupled qubits under a phase damping channel,"Quantification of entanglement against mixing is given for a system of
+coupled qubits under a phase damping channel. A family of pure initial joint
+states is defined, ranging from pure separable states to maximally entangled
+state. An ordering of entanglement measures is given for well defined initial
+state amount of entanglement.",0507212v2
+2005-10-20,Overdamping by weakly coupled environments,"A quantum system weakly interacting with a fast environment usually undergoes
+a relaxation with complex frequencies whose imaginary parts are damping rates
+quadratic in the coupling to the environment, in accord with Fermi's ``Golden
+Rule''. We show for various models (spin damped by harmonic-oscillator or
+random-matrix baths, quantum diffusion, quantum Brownian motion) that upon
+increasing the coupling up to a critical value still small enough to allow for
+weak-coupling Markovian master equations, a new relaxation regime can occur. In
+that regime, complex frequencies lose their real parts such that the process
+becomes overdamped. Our results call into question the standard belief that
+overdamping is exclusively a strong coupling feature.",0510164v1
+2006-06-07,"Comment on ""Optimum Quantum Error Recovery using Semidefinite Programming""","In a recent paper ([1]=quant-ph/0606035) it is shown how the optimal recovery
+operation in an error correction scheme can be considered as a semidefinite
+program. As a possible future improvement it is noted that still better error
+correction might be obtained by optimizing the encoding as well. In this note
+we present the result of such an improvement, specifically for the four-bit
+correction of an amplitude damping channel considered in [1]. We get a strict
+improvement for almost all values of the damping parameter. The method (and the
+computer code) is taken from our earlier study of such correction schemes
+(quant-ph/0307138).",0606059v1
+2006-10-16,Local noise can enhance entanglement teleportation,"Recently we have considered two-qubit teleportation via mixed states of four
+qubits and defined the generalized singlet fraction. For single-qubit
+teleportation, Badziag {\em et al.} [Phys. Rev. A {\bf 62}, 012311 (2000)] and
+Bandyopadhyay [Phys. Rev. A {\bf 65}, 022302 (2002)] have obtained a family of
+entangled two-qubit mixed states whose teleportation fidelity can be enhanced
+by subjecting one of the qubits to dissipative interaction with the environment
+via an amplitude damping channel. Here, we show that a dissipative interaction
+with the local environment via a pair of time-correlated amplitude damping
+channels can enhance fidelity of entanglement teleportation for a class of
+entangled four-qubit mixed states. Interestingly, we find that this enhancement
+corresponds to an enhancement in the quantum discord for some states.",0610125v1
+2006-11-24,High fidelity transfer of an arbitrary quantum state between harmonic oscillators,"It is shown that by switching a specific time-dependent interaction between a
+harmonic oscillator and a transmission line (a waveguide, an optical fiber,
+etc.) the quantum state of the oscillator can be transferred into that of
+another oscillator coupled to the distant other end of the line, with a
+fidelity that is independent of the initial state of both oscillators. For a
+transfer time $T$, the fidelity approaches 1 exponentially in $\gamma T$ where
+$\gamma$ is a characteristic damping rate. Hence, a good fidelity is achieved
+even for a transfer time of a few damping times. Some implementations are
+discussed.",0611249v1
+2006-12-05,Quantum Brownian motion and the second law of thermodynamics,"We consider a single harmonic oscillator coupled to a bath at zero
+temperature. As is well known, the oscillator then has a higher average energy
+than that given by its ground state. Here we show analytically that for a
+damping model with arbitrarily discrete distribution of bath modes and damping
+models with continuous distributions of bath modes with cut-off frequencies,
+this excess energy is less than the work needed to couple the system to the
+bath, therefore, the quantum second law is not violated. On the other hand, the
+second law may be violated for bath modes without cut-off frequencies, which
+are, however, physically unrealistic models.",0612038v1
+2007-05-08,Minimal qudit code for a qubit in the phase-damping channel,"Using the stabilizer formalism we construct the minimal code into a
+D-dimensional Hilbert space (qudit) to protect a qubit against phase damping.
+The effectiveness of this code is then studied by means of input-output
+fidelity.",0705.1099v3
+2007-05-10,Anomalous Diffusion of particles with inertia in external potentials,"Recently a new type of Kramers-Fokker-Planck Equation has been proposed [R.
+Friedrich et al. Phys. Rev. Lett. {\bf 96}, 230601 (2006)] describing anomalous
+diffusion in external potentials. In the present paper the explicit cases of a
+harmonic potential and a velocity-dependend damping are incorporated. Exact
+relations for moments for these cases are presented and the asymptotic
+behaviour for long times is discussed. Interestingly the bounding potential and
+the additional damping by itself lead to a subdiffussive behaviour, while
+acting together the particle becomes localized for long times.",0705.1480v1
+2007-06-13,Polymers in a vacuum,"In a variety of situations, isolated polymer molecules are found in a vacuum
+and here we examine their properties. Angular momentum conservation is shown to
+significantly alter the average size of a chain and its conservation is only
+broken slowly by thermal radiation. The time autocorrelation for monomer
+position oscillates with a characteristic time proportional to chain length.
+The oscillations and damping are analyzed in detail. Short range repulsive
+interactions suppress oscillations and speed up relaxation but stretched chains
+still show damped oscillatory time correlations.",0706.2001v1
+2007-07-15,Enhancement of Carrier Mobility in Semiconductor Nanostructures by Dielectric Engineering,"We propose a technique for achieving large improvements in carrier mobilities
+in 2- and 1-dimensional semiconductor nanostructures by modifying their
+dielectric environments. We show that by coating the nanostructures with
+high-$\kappa$ dielectrics, scattering from Coulombic impurities can be strongly
+damped. Though screening is also weakened, the damping of Coulombic scattering
+is much larger, and the resulting improvement in mobilities of carriers can be
+as much as an order of magnitude for thin 2D semiconductor membranes, and more
+for semiconductor nanowires.",0707.2244v1
+2007-07-23,Causal vs. Noncausal Description of Nonlinear Wave Mixing; Resolving the Damping-Sign Controversy,"Frequency-domain nonlinear wave mixing processes may be described either
+using response functions whereby the signal is generated after all interactions
+with the incoming fields, or in terms of scattering amplitudes where all fields
+are treated symetrically with no specific time ordering. Closed Green's
+function expressions derived for the two types of signals have different
+analytical properties. The recent controversy regarding the sign of radiative
+damping in the linear (Kramers Heisenberg) formula is put in a broader context.",0707.3458v1
+2007-07-27,Excitation of spin dynamics by spin-polarized current in vortex state disks,"A spin-polarized current with the polarization perpendicular to the plane of
+a vortex-state disk results in renormalization of the effective damping for a
+given magnetization mode, and the effective damping becomes zero if the current
+exceeds a threshold value. The lowest threshold current corresponds to the
+lowest frequency vortex gyroscopic mode. For larger values of the current the
+dynamic magnetization state is characterized by precession of the vortex around
+the dot center with non-small amplitude and higher frequency.",0707.4128v1
+2007-09-11,Frequency and damping of the Scissors Mode of a Fermi gas,"We calculate the frequency and damping of the scissors mode in a classical
+gas as a function of temperature and coupling strength. Our results show good
+agreement with the main features observed in recent measurements of the
+scissors mode in an ultracold gas of $^6$Li atoms. The comparison between
+theory and experiment involves no fitting parameters and thus allows an
+identification of non-classical effects at and near the unitarity limit.",0709.1617v2
+2007-09-14,Strong collisionless damping of the low-velocity branch of electromagnetic wave in plasmas with Maxwellian-like electron velocity distribution function,"After approximate replacing of Maxwellian distribution exponent with the
+rational polynomial fraction we have obtained precise analytical expression for
+and calculated the principal value of logarithmically divergent integral in the
+electron wave dispersion equation. At the same time our calculations have shown
+the presence of strong collisionless damping of the electromagnetic
+low-velocity (electron) wave in plasmas with Maxwellian-like electron velocity
+distribution function at some small, of the order of several per cents,
+differences from Maxwellian distribution in the main region of large electron
+densities, however due to the differences in the distribution tail, where
+electron density itself is negligibly small.",0709.2206v1
+2007-09-14,"Plasmons, plasminos and Landau damping in a quasiparticle model of the quark-gluon plasma","A phenomenological quasiparticle model is surveyed for 2+1 quark flavors and
+compared with recent lattice QCD results. Emphasis is devoted to the effects of
+plasmons, plasminos and Landau damping. It is shown that thermodynamic bulk
+quantities, known at zero chemical potential, can uniquely be mapped towards
+nonzero chemical potential by means of a thermodynamic consistency condition
+and a stationarity condition.",0709.2262v2
+2007-10-04,Activation of additional energy dissipation processes in the magnetization dynamics of epitaxial chromium dioxide films,"The precessional magnetization dynamics of a chromium dioxide$(100)$ film is
+examined in an all-optical pump-probe setup. The frequency dependence on the
+external field is used to extract the uniaxial in-plane anisotropy constant.
+The damping shows a strong dependence on the frequency, but also on the laser
+pump fluency, which is revealed as an important experiment parameter in this
+work: above a certain threshold further channels of energy dissipation open and
+the damping increases discontinuously. This behavior might stem from spin-wave
+instabilities.",0710.0986v2
+2007-10-24,Spin dynamics of a trapped spin-1 Bose Gas above the Bose-Einstein transition temperature,"We study collective spin oscillations in a spin-1 Bose gas above the
+Bose-Einstein transition temperature. Starting from the Heisenberg equation of
+motion, we derive a kinetic equation describing the dynamics of a thermal gas
+with the spin-1 degree of freedom. Applying the moment method to the kinetic
+equation, we study spin-wave collective modes with dipole symmetry. The dipole
+modes in the spin-1 system are found to be classified into the three type of
+modes. The frequency and damping rate are obtained as functions of the peak
+density. The damping rate is characterized by three relaxation times associated
+with collisions.",0710.4419v2
+2007-11-19,Nonlinear mode conversion in monodomain magnetic squares,"Modifications of spatial distributions of dynamic magnetization corresponding
+to spinwave eigenmodes of magnetic squares subjected to a strong microwave
+excitation field have been studied experimentally and theoretically. We show
+that an increase of the excitation power leads to a nonlinear generation of
+long-wavelength spatial harmonics caused by the nonlinear cross coupling
+between the eigenmodes. The analysis of the experimental data shows that this
+process is mainly governed by the action of the nonlinear spin-wave damping.
+This conclusion is further supported by the numerical calculations based on the
+complex Ginzburg-Landau equation phenomenologically taking into account the
+nonlinear damping.",0711.2872v1
+2007-12-18,Weibel Instabilities in Dense Quantum Plasmas,"The quantum effect on the Weibel instability in an unmagnetized plasma is
+presented. Our analysis shows that the quantum effect tends to stabilize the
+Weibel instability in the hydrodynamic regime, whereas it produces a new
+oscillatory instability in the kinetic regime. A novel effect the quantum
+damping, which is associated with the Landau damping, is disclosed. The new
+quantum Weibel instability may be responsible for the generation of
+non-stationary magnetic fields in compact astrophysical objects as well as in
+the forthcoming intense laser-solid density plasma experiments.",0712.2874v1
+2008-01-18,A qualitative perspective on the dynamics of a single-Cooper-pair box with a phase-damped cavity,"In a recent paper Dajka, et.al., [J. Phys. A \textbf{40}, F879 (2007)]
+predicted that some composite systems can be entangled forever even if coupled
+with a thermal bath. We analyze the transient entanglement of a
+single-Cooper-pair box biased by a classical voltage and irradiated by a
+quantized field and find the unusual feature that the phase-damped cavity can
+lead to a long-lived entanglement. The results show an asymptotic value of the
+idempotency defect (concurrence) which embodies coherence loss (entanglement
+survival), independent of the interaction development by dependent critically
+on environment.",0801.2905v2
+2008-02-28,Current driven spin-wave instability triggered by the anomalous Hall effect,"We studied the effect of strong electric current on spin waves interacting
+relativistically with the current. The spin-wave spectrum is calculated at
+arbitrary direction of the wave vector. It is shown that the alternating Hall
+current generated by the alternating magnetic moment of the spin waves, reduces
+the spin-wave damping. At strong enough unpolarized dc current the damping
+changes sign, and the spin-wave amplitude starts to increase exponentially fast
+with time. The critical current for the spin-wave instability is determined
+mainly by the anomalous Hall effect, and can be much smaller than that for the
+spin-torque mechanism of instability.",0802.4150v1
+2008-03-31,Spectral Modeling of Magnetohydrodynamic Turbulent Flows,"We present a dynamical spectral model for Large Eddy Simulation of the
+incompressible magnetohydrodynamic (MHD) equations based on the Eddy Damped
+Quasi Normal Markovian approximation. This model extends classical spectral
+Large Eddy Simulations for the Navier-Stokes equations to incorporate general
+(non Kolmogorovian) spectra as well as eddy noise. We derive the model for MHD
+and show that introducing a new eddy-damping time for the dynamics of spectral
+tensors in the absence of equipartition between the velocity and magnetic
+fields leads to better agreement with direct numerical simulations, an
+important point for dynamo computations.",0803.4499v1
+2008-04-10,Trapped Phase-Segregated Bose-Fermi Mixtures and their Collective Excitations,"Recent progress in the field of ultracold gases has allowed the creation of
+phase-segregated Bose-Fermi systems. We present a theoretical study of their
+collective excitations at zero temperature. As the fraction of fermion to boson
+particle number increases, the collective mode frequencies take values between
+those for a fully bosonic and those for a fully fermionic cloud, with damping
+in the intermediate region. This damping is caused by fermions which are
+resonantly driven at the interface.",0804.1759v2
+2008-04-14,Size dependence of multipolar plasmon resonance frequencies and damping rates in simple metal spherical nanoparticles,"Multipolar plasmon oscillation frequencies and corresponding damping rates
+for nanospheres formed of the simplest free-electron metals are studied. The
+possibility of controlling plasmon features by choosing the size and dielectric
+properties of the sphere surroundings is discussed. Optical properties of the
+studied metals are described within the Drude-Sommerfeld model of the
+dielectric function with effective parameters acounting for the contribution of
+conduction electrons and of interband transitions. No approximation is made in
+respect of the size of a particle; plasmon size characteristics are described
+rigorously. The results of our experiment on sodium nanodroplets [1] are
+compared with the oscillation frequency size dependence of dipole and
+quadrupole plasmon.",0804.2156v1
+2008-06-05,Thermally Assisted Spin Hall Effect,"The spin polarized charge transport is systematically analyzed as a thermally
+driven stochastic process. The approach is based on Kramers' equation
+describing the semiclassical motion under the inclusion of stochastic and
+damping forces. Due to the relativistic spin-orbit coupling the damping
+experiences a relativistic correction leading to an additional contribution
+within the spin Hall conductivity. A further contribution to the conductivity
+is originated from the averaged underlying crystal potential, the mean value of
+which depends significantly on the electric field. We derive an exact
+expression for the electrical conductivity. All corrections are estimated in
+lowest order of a relativistic approach and in the linear response regime.",0806.0948v1
+2008-06-13,General Solution of the Quantum Damped Harmonic Oscillator II : Some Examples,"In the preceding paper (arXiv : 0710.2724 [quant-ph]) we have constructed the
+general solution for the master equation of quantum damped harmonic oscillator,
+which is given by the complicated infinite series in the operator algebra
+level. In this paper we give the explicit and compact forms to solutions
+(density operators) for some initial values. In particular, the compact one for
+the initial value based on a coherent state is given, which has not been given
+as far as we know. Moreover, some related problems are presented.",0806.2169v1
+2008-08-27,Entanglement dynamics of two-qubit system in different types of noisy channels,"In this paper, we study entanglement dynamics of a two-qubit extended
+Werner-like state locally interacting with independent noisy channels, i.e.,
+amplitude damping, phase damping and depolarizing channels. We show that the
+purity of initial entangled state has direct impacts on the entanglement
+robustness in each noisy channel. That is, if the initial entangled state is
+prepared in mixed instead of pure form, the state may exhibit entanglement
+sudden death (ESD) and/or be decreased for the critical probability at which
+the entanglement disappear.",0808.3690v1
+2008-09-01,Heatons induced by attosecond laser pulses,"In this paper the dynamics of the interaction of attosecond laser pulses with
+matter is investigated. It will be shown that the master equation: modified
+Klein-Gordon equation describes the propagation of the heatons. Heatons are the
+thermal wave packets. When the duration of the laser pulses is of the order of
+attosecond the heaton thermal wave packets are nondispersive objects. For
+infinite time the heatons are damped with damping factor of the order of
+relaxation time for thermal processes.",0809.0204v1
+2008-10-09,Heat conduction in 2D strongly-coupled dusty plasmas,"We perform non-equilibrium simulations to study heat conduction in
+two-dimensional strongly coupled dusty plasmas. Temperature gradients are
+established by heating one part of the otherwise equilibrium system to a higher
+temperature. Heat conductivity is measured directly from the stationary
+temperature profile and heat flux. Particular attention is paid to the
+influence of damping effect on the heat conduction. It is found that the heat
+conductivity increases with the decrease of the damping rate, while its
+magnitude agrees with previous experimental measurement.",0810.1623v2
+2008-10-21,Structurally damped plate and wave equations with random point force in arbitrary space dimensions,"In this paper we consider structurally damped plate and wave equations with
+point and distributed random forces. In order to treat space dimensions more
+than one, we work in the setting of $L^q$--spaces with (possibly small)
+$q\in(1,2)$. We establish existence, uniqueness and regularity of mild and weak
+solutions to the stochastic equations employing recent theory for stochastic
+evolution equations in UMD Banach spaces.",0810.3898v2
+2008-11-05,Spectral function and quasi-particle damping of interacting bosons in two dimensions,"We employ the functional renormalization group to study dynamical properties
+of the two-dimensional Bose gas. Our approach is free of infrared divergences,
+which plague the usual diagrammatic approaches, and is consistent with the
+exact Nepomnyashchy identity, which states that the anomalous self-energy
+vanishes at zero frequency and momentum. We recover the correct infrared
+behavior of the propagators and present explicit results for the spectral
+line-shape, from which we extract the quasi-particle dispersion and damping.",0811.0624v2
+2008-11-13,Existence of weak solutions to the Cauchy problem of a semilinear wave equation with supercritical interior source and damping,"In this paper we show existence of finite energy solutions for the Cauchy
+problem associated with a semilinear wave equation with interior damping and
+supercritical source terms. The main contribution consists in dealing with
+super-supercritical source terms (terms of the order of $|u|^p$ with $p\geq 5$
+in $n=3$ dimensions), an open and highly recognized problem in the literature
+on nonlinear wave equations.",0811.2151v1
+2008-11-17,Asymptotic stability and blow up for a semilinear damped wave equation with dynamic boundary conditions,"In this paper we consider a multi-dimensional wave equation with dynamic
+boundary conditions, related to the Kelvin-Voigt damping. Global existence and
+asymptotic stability of solutions starting in a stable set are proved. Blow up
+for solutions of the problem with linear dynamic boundary conditions with
+initial data in the unstable set is also obtained.",0811.2783v3
+2008-11-19,Weyl laws for partially open quantum maps,"We study a toy model for ""partially open"" wave-mechanical system, like for
+instance a dielectric micro-cavity, in the semiclassical limit where ray
+dynamics is applicable. Our model is a quantized map on the 2-dimensional
+torus, with an additional damping at each time step, resulting in a subunitary
+propagator, or ""damped quantum map"". We obtain analogues of Weyl's laws for
+such maps in the semiclassical limit, and draw some more precise estimates when
+the classical dynamic is chaotic.",0811.3134v2
+2008-12-16,A picogram and nanometer scale photonic crystal opto-mechanical cavity,"We describe the design, fabrication, and measurement of a cavity
+opto-mechanical system consisting of two nanobeams of silicon nitride in the
+near-field of each other, forming a so-called ""zipper"" cavity. A photonic
+crystal patterning is applied to the nanobeams to localize optical and
+mechanical energy to the same cubic-micron-scale volume. The picrogram-scale
+mass of the structure, along with the strong per-photon optical gradient force,
+results in a giant optical spring effect. In addition, a novel damping regime
+is explored in which the small heat capacity of the zipper cavity results in
+blue-detuned opto-mechanical damping.",0812.2953v1
+2009-02-03,Freezing of spin dynamics in underdoped cuprates,"The Mori's memory function approach to spin dynamics in doped
+antiferromagnetic insulator combined with the assumption of temperature
+independent static spin correlations and constant collective mode damping leads
+to w/T scaling in a broad range. The theory involving a nonuniversal scaling
+parameter is used to analyze recent inelastic neutron scattering results for
+underdoped cuprates. Adopting modified damping function also the emerging
+central peak in low-doped cuprates at low temperatures can be explained within
+the same framework.",0902.0546v1
+2009-02-12,"Discrete breathers in a forced-damped array of coupled pendula: Modeling, Computation and Experiment","In this work, we present a mechanical example of an experimental realization
+of a stability reversal between on-site and inter-site centered localized
+modes. A corresponding realization of a vanishing of the Peierls-Nabarro
+barrier allows for an experimentally observed enhanced mobility of the
+localized modes near the reversal point. These features are supported by
+detailed numerical computations of the stability and mobility of the discrete
+breathers in this system of forced and damped coupled pendula. Furthermore,
+additional exotic features of the relevant model, such as dark breathers are
+briefly discussed.",0902.2129v1
+2009-03-08,Enhancement of transmission rates in quantum memory channels with damping,"We consider the transfer of quantum information down a single-mode quantum
+transmission line. Such quantum channel is modeled as a damped harmonic
+oscillator, the interaction between the information carriers -a train of N
+qubits- and the oscillator being of the Jaynes-Cummings kind. Memory effects
+appear if the state of the oscillator is not reset after each channel use. We
+show that the setup without resetting is convenient in order to increase the
+transmission rates, both for the transfer of quantum and classical private
+information. Our results can be applied to the micromaser.",0903.1424v1
+2009-03-15,A variational approach to strongly damped wave equations,"We discuss a Hilbert space method that allows to prove analytical
+well-posedness of a class of linear strongly damped wave equations. The main
+technical tool is a perturbation lemma for sesquilinear forms, which seems to
+be new. In most common linear cases we can furthermore apply a recent result
+due to Crouzeix--Haase, thus extending several known results and obtaining
+optimal analyticity angle.",0903.2599v2
+2009-03-30,Damping of Exciton Rabi Rotations by Acoustic Phonons in Optically Excited InGaAs/GaAs Quantum Dots,"We report experimental evidence identifying acoustic phonons as the principal
+source of the excitation-induced-dephasing (EID) responsible for the intensity
+damping of quantum dot excitonic Rabi rotations. The rate of EID is extracted
+from temperature dependent Rabi rotation measurements of the ground-state
+excitonic transition, and is found to be in close quantitative agreement with
+an acoustic-phonon model.",0903.5278v2
+2009-05-13,Landau damping,"In this note we present the main results from the recent work
+hal-00376547/arXiv:0904.2760, which for the first time establish Landau damping
+in a nonlinear context.",0905.2167v2
+2009-05-13,Amortissement Landau,"Dans cette note nous pr\'esentons les principaux r\'esultats du r\'ecent
+travail hal-00376547/arXiv:0904.2760, o\`u le ph\'enom\`ene d'amortissement
+Landau est pour la premi\`ere fois \'etabli dans un contexte non lin\'eaire.
+  -----
+  In this note we present the main results from the recent work hal-00376547 /
+arXiv:0904.2760, which for the first time establish Landau damping in a
+nonlinear context.",0905.2168v2
+2009-06-27,Effect of Bohm potential on a charged gas,"Bohm's interpretation of Quantum Mechanics leads to the derivation of a
+Quantum Kinetic Equation (QKE): in the present work, propagation of waves in
+charged quantum gases is investigated starting from this QKE. Dispersion
+relations are derived for fully and weakly degenerate fermions and bosons
+(these latter above critical temperature), and the differences underlined. Use
+of a kinetic equation permits investigation of ""Landau-type"" damping: it is
+found that the presence of damping in fermion gases is dependent upon the
+degree of degeneracy, whereas it is always present in boson gases. In fully
+degenerate fermions a phenomenon appears that is akin to the ""zero sound""
+propagation.",0906.5061v1
+2009-07-14,Quantum Monty Hall problem under decoherence,"We study the effect of decoherence on quantum Monty Hall problem under the
+influence of amplitude damping, depolarizing and dephasing channels. It is
+shown that under the effect of decoherence, there is a Nash equilibrium of the
+game in case of depolarizing channel for Alice's quantum strategy. Where as in
+case of dephasing noise, the game is not influenced by the quantum channel. For
+amplitude damping channel, the Bob's payoffs are found symmetrical with maximum
+at p=0.5 against his classical strategy. However, it is worth-mentioning that
+in case of depolarizing channel, Bob's classical strategy remains always
+dominant against any choice of Alice's strategy.",0907.2293v1
+2009-08-31,Rigorous Theory of Optical Trapping by an Optical Vortex Beam,"We propose a rigorous theory for the optical trapping by optical vortices,
+which is emerging as an important tool to trap mesoscopic particles. The common
+perception is that the trapping is solely due to the gradient force, and may be
+characterized by three real force constants. However, we show that the optical
+vortex trap can exhibit complex force constants, implying that the trapping
+must be stabilized by ambient damping. At different damping levels, particle
+shows remarkably different dynamics, such as stable trapping, periodic and
+aperiodic orbital motions.",0908.4504v1
+2009-09-11,Energy decay for the damped wave equation under a pressure condition,"We establish the presence of a spectral gap near the real axis for the damped
+wave equation on a manifold with negative curvature. This results holds under a
+dynamical condition expressed by the negativity of a topological pressure with
+respect to the geodesic flow. As an application, we show an exponential decay
+of the energy for all initial data sufficiently regular. This decay is governed
+by the imaginary part of a finite number of eigenvalues close to the real axis.",0909.2093v1
+2009-09-12,Signature of smooth transition from diabatic to adiabatic states in heavy-ion fusion reactions at deep subbarrier energies,"We propose a novel extension of the standard coupled-channels framework for
+heavy-ion reactions in order to analyze fusion reactions at deep subbarrier
+incident energies. This extension simulates a smooth transition between the
+diabatic two-body and the adiabatic one-body states. To this end, we damp
+gradually the off-diagonal part of the coupling potential, for which the
+position of the onset of the damping varies for each eigen channel. We show
+that this model accounts well for the steep falloff of the fusion cross
+sections for the $^{16}$O+$^{208}$Pb, $^{64}$Ni+$^{64}$Ni, and
+$^{58}$Ni+$^{58}$Ni reactions.",0909.2298v1
+2009-10-14,Plasmon-phonon Strongly-Coupled Mode in Epitaxial Graphene,"We report the dispersion measurements, using angle-resolved reflection
+electron-energy-loss-spectroscopy (AREELS), on two-dimensional (2D) plasmons in
+single and multilayer graphene which couple strongly to surface optical phonon
+(FK phonon) modes of silicon carbide substrate. The coupled modes show discrete
+dispersion behaviors in the single and bilayer graphene. With increasing
+graphene layers on SiC(0001), a transition from plasmon-like dispersion to
+phonon-like dispersion is observed. For plasmon-like modes, the dispersion is
+strongly damped by electron-hole pair excitations at entering single-particle
+continuum, while phonon-like mode is undamped. In the region free of coupling,
+the graphene 2D plasmon exhibits acoustic behavior with linear dispersion with
+slope and damping determined by the Fermi surface topology.",0910.2735v1
+2009-10-23,Collective Enhancement and Suppression of Excitation Decay in Optical Lattices,"We calculate radiative lifetimes of collective electronic excitations of
+atoms in an infinite one dimensional lattice. The translational symmetry along
+the lattice restricts the photon wave vector component parallel to the lattice
+to the exciton wave number and thus the possible emission directions. The
+resulting radiation damping rate and emission pattern of the exciton strongly
+deviates from independent atom. For some wave numbers and polarizations the
+excitons superradiantly decay very fast, while other excitons show zero
+radiation damping rate and form propagating meta-stable excitations. Such
+states could be directly coupled via tailored evanescent fields from a nearby
+fiber.",0910.4501v1
+2009-10-24,Global Attractor for Weakly Damped Forced KdV Equation in Low Regularity on T,"In this paper we consider the long time behavior of the weakly damped, forced
+Korteweg-de Vries equation in the Sololev spaces of the negative indices in the
+periodic case. We prove that the solutions are uniformly bounded in
+$\dot{H}^s(\T)$ for $s>-\dfrac{1}{2}$. Moreover, we show that the solution-map
+possesses a global attractor in $\dot{H}^s(\T)$ for $s>-\dfrac{1}{2}$, which is
+a compact set in $H^{s+3}(\T)$.",0910.4652v1
+2009-10-24,Two bodies gravitational system with variable mass and damping-antidamping effect due to star wind,"We study two-bodies gravitational problem where the mass of one of the bodies
+varies and suffers a damping-antidamping effect due to star wind during its
+motion. A constant of motion, a Lagrangian and a Hamiltonian are given for the
+radial motion of the system, and the period of the body is studied using the
+constant of motion of the system. An application to the comet motion is given,
+using the comet Halley as an example.",0910.4684v2
+2009-12-15,Distillability sudden death in qutrit-qutrit systems under amplitude damping,"Recently it has been discovered that certain two-qutrit entangled states
+interacting with global and/or multi-local decoherence undergo distillability
+sudden death (DSD). We investigate this phenomenon for qutrit-qutrit systems
+interacting with statistically independent zero-temperature reservoirs. We show
+that certain initially prepared free-entangled states become bound-entangled in
+a finite time due to the action of Markovian dissipative environment. Moreover,
+in contrast with local dephasing, simple local unitary transformations can
+completely avoid distillability sudden death under amplitude damping.",0912.2868v1
+2009-12-15,Global Controllability of Multidimensional Rigid Body by Few Torques,"We study global controllability of 'rotating' multidimensional rigid body
+(MRB) controlled by application of few torques. Study by methods of geometric
+control requires analysis of algebraic structure introduced by the quadratic
+term of Euler-Frahm equation. We discuss problems, which arise in the course of
+this analysis, and establish several global controllability criteria for damped
+and non damped cases.",0912.2900v1
+2010-02-05,Damping Effect of Electromagnetic Radiation and Time-Dependent Schrodinger Equation,"The inexactness of the time-dependent Schr\""odinger equation of a charged
+particle in an external electromagnetic field is discussed in terms of the
+damping effect of the radiation. A possible improvement is to add a nonlinear
+term representing this effect to the linear Schr\""odinger equation. Conditions
+for the nonlinear term are investigated and it is demonstrated that the
+obtained nonlinear Schr\""odinger equation may present state evolutions similar
+to the wave-function reduction and transitions between stationary states.",1002.1116v3
+2010-02-05,Uniform stabilization in weighted Sobolev spaces for the KdV equation posed on the half-line,"Studied here is the large-time behavior of solutions of the Korteweg-de Vries
+equation posed on the right half-line under the effect of a localized damping.
+Assuming as in \cite{linares-pazoto} that the damping is active on a set
+$(a_0,+\infty)$ with $a_0>0$, we establish the exponential decay of the
+solutions in the weighted spaces $L^2((x+1)^mdx)$ for $m\in \N ^*$ and
+$L^2(e^{2bx}dx)$ for $b>0$ by a Lyapunov approach. The decay of the spatial
+derivatives of the solution is also derived.",1002.1127v1
+2010-03-28,Giant magnetic broadening of ferromagnetic resonance in a GMR Co/Ag/Co/Gd quadlayer,"Both magnetic-resonance damping and the giant magnetoresistance effect have
+been predicted to be strongly affected by the local density of states in thin
+ferromagnetic films. We employ the antiferromagnetic coupling between Co and Gd
+to provide a spontaneous change from parallel to antiparallel alignment of two
+Co films. A sharp increase in magnetic damping accompanies the change from
+parallel to antiparallel alignment, analogous to resistivity changes in giant
+magnetoresistance.",1003.5344v1
+2010-04-04,Quantum information reclaiming after amplitude damping,"We investigate the quantum information reclaim from the environment after
+amplitude damping has occurred. In particular we address the question of
+optimal measurement on the environment to perform the best possible correction
+on two and three dimensional quantum systems. Depending on the dimension we
+show that the entanglement fidelity (the measure quantifying the correction
+performance) is or is not the same for all possible measurements and uncover
+the optimal measurement leading to the maximum entanglement fidelity.",1004.0497v1
+2010-04-09,Validity of Landauer's principle in the quantum regime,"We demonstrate the validity of Landauer's erasure principle in the strong
+coupling quantum regime by treating the system-reservoir interaction in a
+consistent way. We show that the initial coupling to the reservoir modifies
+both energy and entropy of the system and provide explicit expressions for the
+latter in the case of a damped quantum harmonic oscillator. These contributions
+are related to the Hamiltonian of mean force and dominate in the strong damping
+limit. They need therefore to be fully taken into account in any
+low-temperature thermodynamic analysis of quantum systems.",1004.1599v1
+2010-04-22,Critical exponent for damped wave equations with nonlinear memory,"We consider the Cauchy problem in $\mathbb{R}^n,$ $n\geq 1,$ for a semilinear
+damped wave equation with nonlinear memory. Global existence and asymptotic
+behavior as $t\rightarrow\infty$ of small data solutions have been established
+in the case when $1\leq n\leq3.$ Moreover, we derive a blow-up result under
+some positive data in any dimensional space.",1004.3850v4
+2010-04-26,Entanglement of a two-particle Gaussian state interacting with a heat bath,"The effect of a thermal reservoir is investigated on a bipartite Gaussian
+state. We derive a pre-Lindblad master equation in the non-rotating wave
+approximation for the system. We then solve the master equation for a bipartite
+harmonic oscillator Hamiltonian with entangled initial state. We show that for
+strong damping the loss of entanglement is the same as for freely evolving
+particles. However, if the damping is small, the entanglement is shown to
+oscillate and eventually tend to a constant nonzero value.",1004.4515v2
+2010-04-27,Radiation Damping in a Non-Abelian Strongly-Coupled Gauge Theory,"We study a `dressed' or `composite' quark in strongly-coupled N=4
+super-Yang-Mills (SYM), making use of the AdS/CFT correspondence. We show that
+the standard string dynamics nicely captures the physics of the quark and its
+surrounding quantum non-Abelian field configuration, making it possible to
+derive a relativistic equation of motion that incorporates the effects of
+radiation damping. From this equation one can deduce a non-standard dispersion
+relation for the composite quark, as well as a Lorentz covariant formula for
+its rate of radiation.",1004.4912v1
+2010-05-21,Quantization of the Damped Harmonic Oscillator Revisited,"We return to the description of the damped harmonic oscillator by means of a
+closed quantum theory with a general assessment of previous works, in
+particular the Bateman-Caldirola-Kanai model and a new model recently proposed
+by one of the authors. We show the local equivalence between the two models and
+argue that latter has better high energy behavior and is naturally connected to
+existing open-quantum-systems approaches.",1005.4096v1
+2010-06-09,Dispersion and damping of two-dimensional dust acoustic waves: Theory and Simulation,"A two-dimensional generalized hydrodynamics (GH) model is developed to study
+the full spectrum of both longitudinal and transverse dust acoustic waves (DAW)
+in strongly coupled complex (dusty) plasmas, with memory-function-formalism
+being implemented to enforce high-frequency sum rules. Results are compared
+with earlier theories (such as quasi-localized charge approximation and its
+extended version) and with a self-consistent Brownian dynamics simulation. It
+is found that the GH approach provides good account, not only for dispersion
+relations, but also for damping rates of the DAW modes in a wide range of
+coupling strengths, an issue hitherto not fully addressed for dusty plasmas.",1006.1799v1
+2010-07-01,Finite time extinction by nonlinear damping for Schrodinger equation,"We consider the Schrodinger equation on a compact manifold, in the presence
+of a nonlinear damping term, which is homogeneous and sublinear. For initial
+data in the energy space, we construct a weak solution, defined for all
+positive time, which is shown to be unique. In the one-dimensional case, we
+show that it becomes zero in finite time. In the two and three-dimensional
+cases, we prove the same result under the assumption of extra regularity on the
+initial datum.",1007.0077v2
+2010-07-07,Spin drag Hall effect in a rotating Bose mixture,"We show that in a rotating two-component Bose mixture, the spin drag between
+the two different spin species shows a Hall effect. This spin drag Hall effect
+can be observed experimentally by studying the out-of-phase dipole mode of the
+mixture. We determine the damping of this mode due to spin drag as a function
+of temperature. We find that due to Bose stimulation there is a strong
+enhancement of the damping for temperatures close to the critical temperature
+for Bose-Einstein condensation.",1007.1088v1
+2010-08-30,Synthesis of electrical networks interconnecting PZT actuators to damp mechanical vibrations,"This paper proves that it is possible to damp mechanical vibrations of some
+beam frames by means of piezoelectric actuators interconnected via passive
+networks. We create a kind of electromechanical wave guide where the electrical
+velocity group equals the mechanical one thus enabling an electromechanical
+energy transfer. Numerical simulations are presented which prove the technical
+feasibility of proposed device",1008.5112v1
+2010-09-15,Anomalous High-Energy Spin Excitations in La2CuO4,"Inelastic neutron scattering is used to investigate the collective magnetic
+excitations of the high-temperature superconductor parent antiferromagnet
+La2CuO4. We find that while the lower energy excitations are well described by
+spin-wave theory, including one- and two-magnon scattering processes, the
+high-energy spin waves are strongly damped near the (1/2,0) position in
+reciprocal space and merge into a momentum dependent continuum. This anomalous
+damping indicates the decay of spin waves into other excitations, possibly
+unbound spinon pairs.",1009.2915v1
+2010-10-05,Damping of dHvA oscillations and vortex-lattice disorder in the peak-effect region of strong type-II superconductors,"The phenomenon of magnetic quantum oscillations in the superconducting state
+poses several questions that still defy satisfactory answers. A key
+controversial issue concerns the additional damping observed in the vortex
+state. Here, we show results of \mu SR, dHvA, and SQUID magnetization
+measurements on borocarbide superconductors, indicating that a sharp drop
+observed in the dHvA amplitude just below H_{c2} is correlated with enhanced
+disorder of the vortex lattice in the peak-effect region, which significantly
+enhances quasiparticle scattering by the pair potential.",1010.0929v1
+2010-10-21,Classical behavior of strongly correlated Fermi systems near a quantum critical point. Transport properties,"The low-temperature kinetics of the strongly correlated electron liquid
+inhabiting a solid is analyzed. It is demonstrated that a softly damped branch
+of transverse zero sound emerges when several bands cross the Fermi surface
+simultaneously near a quantum critical point at which the density of states
+diverges. Suppression of the damping of this branch occurs due to a mechanism
+analogous to that affecting the phonon mode in solids at room temperature,
+giving rise to a classical regime of transport at extremely low temperatures in
+the strongly correlated Fermi system.",1010.4547v1
+2010-10-26,Open Quantum Systems in Noninertial Frames,"We study the effects of decoherence on the entanglement generated by Unruh
+effect in noninertial frames by using bit flip, phase damping and depolarizing
+channels. It is shown that decoherence strongly influences the initial state
+entanglement. The entanglement sudden death can happens irrespective of the
+acceleration of the noninertial frame under the action of phase flip and phase
+damping channels. It is investigated that an early sudden death happens for
+large acceleration under the depolarizing environment. Moreover, the
+entanglement increases for a highly decohered phase flip channel.",1010.5395v1
+2010-11-17,Faint Resonantly Scattered Lyman Alpha Emission from the Absorption Troughs of Damped Lyman Alpha Systems at z ~ 3,"We demonstrate that the Lyman alpha emission in the absorption troughs of a
+large sample of stacked damped Lyman alpha absorption systems (DLAS) presented
+by Rahmani et al (2010) is consistent with the spectral profiles and
+luminosities of a recently detected population of faint Lyman alpha emitters at
+z ~ 3. This result supports the suggestion that the faint emitters are to be
+identified with the host galaxies of DLAS at these redshifts.",1011.4061v1
+2010-12-19,Quantum damping of Fermi-Pasta-Ulam revivals in ultracold Bose gases,"We propose an experimental scheme for studying the Fermi-Pasta-Ulam (FPU)
+phenomenon in a quantum mechanical regime using ultracold atoms. Specifically,
+we suggest and analyze a setup of one-dimensional Bose gases confined into an
+optical lattice. The strength of quantum fluctuations is controlled by tuning
+the number of atoms per lattice sites (filling factor). By simulating the
+real-time dynamics of the Bose-Hubbard model by means of the exact numerical
+method of time-evolving block decimation, we investigate the effects of quantum
+fluctuations on the FPU recurrence and show that strong quantum fluctuations
+cause significant damping of the FPU oscillation.",1012.4159v1
+2010-12-21,Pullback attractors for a singularly nonautonomous plate equation,"We consider the family of singularly nonautonomous plate equation with
+structural damping \[ u_{tt} + a(t,x)u_{t} + (- \Delta) u_{t} + (-\Delta)^{2} u
++ \lambda u = f(u), \] in a bounded domain $\Omega \subset \R^n$, with Navier
+boundary conditions. When the nonlinearity $f$ is dissipative we show that this
+problem is globally well posed in $H^2_0(\Omega) \times L^2(\Omega)$ and has a
+family of pullback attractors which is upper-semicontinuous under small
+perturbations of the damping $a$.",1012.4749v1
+2010-12-30,On rotational solutions for elliptically excited pendulum,"The author considers the planar rotational motion of the mathematical
+pendulum with its pivot oscillating both vertically and horizontally, so the
+trajectory of the pivot is an ellipse close to a circle. The analysis is based
+on the exact rotational solutions in the case of circular pivot trajectory and
+zero gravity. The conditions for existence and stability of such solutions are
+derived. Assuming that the amplitudes of excitations are not small while the
+pivot trajectory has small ellipticity the approximate solutions are found both
+for high and small linear damping. Comparison between approximate and numerical
+solutions is made for different values of the damping parameter.",1101.0062v1
+2011-03-10,Laser-like vibrational instability in rectifying molecular conductors,"We study the damping of molecular vibrations due to electron-hole pair
+excitations in donor-acceptor(D-A) type molecular rectifiers. At finite voltage
+additional non-equilibrium electron-hole pair excitations involving both
+electrodes become possible, and contribute to the stimulated emission and
+absorption of phonons. We point out a generic mechanism for D-A molecules,
+where the stimulated emission can dominate beyond a certain voltage due to
+inverted position of the D and A quantum resonances. This leads to
+current-driven amplification (negative damping) of the phonons similar to
+laser-action. We investigate the effect in realistic molecular rectifier
+structures using first principles calculations.",1103.1990v1
+2011-03-11,Spin Transport in Polaronic and Superfluid Fermi Gases,"We present measurements of spin transport in ultracold gases of fermionic
+lithium-6 in a mixture of two spin states at a Feshbach resonance. In
+particular, we study the spin dipole mode, where the two spin components are
+displaced from each other against a harmonic restoring force. We prepare a
+highly-imbalanced, or polaronic, spin mixture with a spin dipole excitation and
+observe strong, unitarity limited damping of the spin dipole mode. In gases
+with small spin imbalance, below the Pauli limit for superfluidity, we observe
+strongly damped spin flow despite the presence of a superfluid core.",1103.2337v1
+2011-03-14,Tidal Evolution of a Secularly Interacting Planetary System,"In a multi-planet system, a gradual change in one planet's semi-major axis
+will affect the eccentricities of all the planets, as angular momentum is
+distributed via secular interactions. If tidal dissipation in the planet is the
+cause of the change in semi-major axis, it also damps that planet's
+eccentricity, which in turn also contributes to the evolution of all the
+eccentricities. Formulae quantifying the combined effects on the whole system
+due to semi-major axis changes, as well as eccentricity damping, are derived
+here for a two-planet system. The CoRoT 7 system is considered as an example.",1103.2794v1
+2011-03-30,Damping in quantum love affairs,"In a series of recent papers we have used an operatorial technique to
+describe stock markets and, in a different context, {\em love affairs} and
+their time evolutions. The strategy proposed so far does not allow any dumping
+effect. In this short note we show how, within the same framework, a strictly
+non periodic or quasi-periodic effect can be introduced in the model by
+describing in some details a linear Alice-Bob love relation with damping.",1103.5907v1
+2011-04-03,Spatially confined Bloch oscillations in semiconductor superlattices,"In a semiconductor superlattice with long scattering times, damping of Bloch
+oscillations due to scattering is so small that convective nonlinearities may
+compensate it and Bloch oscillations persist even in the hydrodynamic regime.
+In this case, numerical solutions show that there are stable Bloch oscillations
+confined to a region near the collector with inhomogeneous field, charge,
+current density and energy density profiles. These Bloch oscillations disappear
+when damping due to inelastic collisions becomes sufficiently strong.",1104.0429v2
+2011-04-06,Relativistic magnetic reconnection at X-type neutral points,"Relativistic effects in the oscillatory damping of magnetic disturbances near
+two-dimensional X-points are investigated. By taking into account displacement
+current, we study new features of extremely magnetized systems, in which the
+Alfv\'en velocity is almost the speed of light. The frequencies of the
+least-damped mode are calculated using linearized relativistic MHD equations
+for wide ranges of the Lundquist number S and the magnetization parameter
+$\sigma$. These timescales approach constant values in the large resistive
+limit: the oscillation time becomes a few times the light crossing time,
+irrespective of $\sigma$, and the decay time is proportional to $\sigma$ and
+therefore is longer for a highly magnetized system.",1104.1003v1
+2011-04-06,Observed damping of the slow magnetoacoustic mode,"Spectroscopic and stereoscopic imaging observations of slow magnetoacoustic
+wave propagation within a coronal loop are investigated to determine the decay
+length scale of the slow magnetoacoustic mode in three dimensions and the
+density profile within the loop system. The slow wave is found to have an
+e-folding decay length scale of $20,000^{+4000}_{-3000}$km with a uniform
+density profile along the loop base. These observations place quantitive
+constraints on the modelling of wave propagation within coronal loops.
+Theoretical forward modelling suggests that magnetic field line divergence is
+the dominant damping factor and thermal conduction is insufficient, given the
+observed parameters of the coronal loop temperature, density and wave mode
+period.",1104.1100v1
+2011-04-17,Stochastic Wave Equations with Nonlinear Damping and Source Terms,"In this paper, we discuss an initial boundary value problem for the
+stochastic wave equation involving the nonlinear damping term $|u_t|^{q-2}u_t$
+and a source term of the type $|u|^{p-2}u$. We firstly establish the local
+existence and uniqueness of solution by the Galerkin approximation method and
+show that the solution is global for $q\geq p$. Secondly, by an appropriate
+energy inequality, the local solution of the stochastic equations will blow up
+with positive probability or explosive in energy sense for $p>q$.",1104.3279v2
+2011-05-07,Cooperative scattering measurement of coherence in a spatially modulated Bose gas,"Correlations of a Bose gas released from an optical lattice are measured
+using superradiant scattering. Conditions are chosen so that after initial
+incident light pumping at the Bragg angle for diffraction, due to matter wave
+amplification and mode competition, superradiant scattering into the Bragg
+diffracted mode is preponderant. A temporal analysis of the superradiant
+scattering gain reveals periodical oscillations and damping due to the initial
+lack of coherence between lattice sites. Such damping is used for
+characterizing first order spatial correlations in our system with a precision
+of one lattice period.",1105.1425v1
+2011-06-09,Hamiltonian of mean force for damped quantum systems,"We consider a quantum system linearly coupled to a reservoir of harmonic
+oscillators. For finite coupling strengths, the stationary distribution of the
+damped system is not of the Gibbs form, in contrast to standard thermodynamics.
+With the help of the quantum Hamiltonian of mean force, we quantify this
+deviation exactly for a harmonic oscillator and provide approximations in the
+limit of high and low temperatures, and weak and strong couplings. Moreover, in
+the semiclassical regime, we use the quantum Smoluchowski equation to obtain
+results valid for any potential. We, finally, give a physical interpretation of
+the deviation in terms of the initial system-reservoir coupling.",1106.1775v1
+2011-06-17,Current effect on magnetization oscillations in a ferromagnet - antiferromagnet junction,"Spin-polarized current effect is studied on the static and dynamic
+magnetization of the antiferromagnet in a ferromagnet - antiferromagnet
+junction. The macrospin approximation is generalized to antiferromagnets.
+Canted antiferromagnetic configuration and resulting magnetic moment are
+induced by an external magnetic field. The resonance frequency and damping are
+calculated, as well as the threshold current density corresponding to
+instability appearance. A possibility is shown of generating low-damping
+magnetization oscillations in terahertz range. The fluctuation effect is
+discussed on the canted antiferromagnetic configuration.",1106.3519v1
+2011-06-23,Dissipation evidence for the quantum damped harmonic oscillator via pseudo-bosons,"It is known that a self-adjoint, time-independent hamiltonian can be defined
+for the quantum damped harmonic oscillator. We show here that the two vacua
+naturally associated to this operator, when expressed in terms of
+pseudo-bosonic lowering and raising operators, appear to be non
+square-integrable. This fact is interpreted as the evidence of the dissipation
+effect of the classical oscillator at a purely quantum level.",1106.4638v1
+2011-07-15,"Aspects of General Relativity: Pseudo-Finsler extensions, Quasi-normal frequencies and Multiplication of tensorial distributions","This thesis is based on three different projects, all of them are directly
+linked to the classical general theory of relativity, but they might have
+consequences for quantum gravity as well. The first chapter deals with
+pseudo-Finsler geometric extensions of the classical theory, these being ways
+of naturally representing high-energy Lorentz symmetry violations. The second
+chapter deals with the problem of highly damped quasi-normal modes related to
+different types of black hole spacetimes. Besides the astrophysical meaning of
+the quasi-normal modes, there are conjectures about the link between the highly
+damped modes and black hole thermodynamics. The third chapter is related to the
+topic of multiplication of tensorial distributions.",1107.2978v1
+2011-08-08,"Synchrotron radiation damping, intrabeam scattering and beam-beam simulations for HE-LHC","The proposed High-Energy LHC project presents an unusual combination of
+strong synchrotron radiation (SR) damping and intrabeam scattering (IBS), which
+is not seen in present-day hadron colliders. The subject of investigation
+reported in this paper was the simulation of beam-beam effect for the HE-LHC
+parameters. Parameters of SR and IBS are calculated, and the luminosity
+evolution is simulated in the absence of beambeam interaction. Then, a
+weak-strong numerical simulation is used to predict the effect of beam-beam
+interaction on particle losses and emittance evolution.",1108.1644v1
+2011-09-09,Delocalization of slowly damped eigenmodes on Anosov manifolds,"We look at the properties of high frequency eigenmodes for the damped wave
+equation on a compact manifold with an Anosov geodesic flow. We study
+eigenmodes with spectral parameters which are asymptotically close enough to
+the real axis. We prove that such modes cannot be completely localized on
+subsets satisfying a condition of negative topological pressure. As an
+application, one can deduce the existence of a ""strip"" of logarithmic size
+without eigenvalues below the real axis under this dynamical assumption on the
+set of undamped trajectories.",1109.1909v2
+2011-10-18,Life times and chirality of spin-waves in antiferromagnetic and ferromagnetic FeRh: time depedent density functional theory perspective,"The study of the spin excitations in antiferromagnetic (AFM) and
+ferromagnetic (FM) phases of FeRh is reported. We demonstrate that although the
+Fe atomic moments are well defined there is a number of important phenomena
+absent in the Heisenberg description: Landau damping of spin waves, large Rh
+moments induced by the AFM magnons, the formation of the optical magnons
+terminated by Stoner excitations. We relate the properties of the spin-wave
+damping to the features of the Stoner continuum and compare the chirality of
+the spin excitations in AFM, FM and paramagnetic (PM) systems.",1110.3913v1
+2011-10-21,Environment-Assisted Error Correction of Single-Qubit Phase Damping,"Open quantum system dynamics of random unitary type may in principle be fully
+undone. Closely following the scheme of environment-assisted error correction
+proposed by Gregoratti and Werner [M. Gregoratti and R. F. Werner, J. Mod. Opt.
+50(6), 915-933 (2003)], we explicitly carry out all steps needed to invert a
+phase-damping error on a single qubit. Furthermore, we extend the scheme to a
+mixed-state environment. Surprisingly, we find cases for which the uncorrected
+state is closer to the desired state than any of the corrected ones.",1110.4806v1
+2011-11-01,Damping of tensor modes in inflation,"We discuss the damping of tensor modes due to anisotropic stress in
+inflation. The effect is negligible in standard inflation and may be
+significantly large in inflation models that involve drastic production of
+free-streaming particles.",1111.0295v3
+2011-11-04,Global uniform asymptotic stabilization and k-exponential trajectory tracking of underactuated surface ships with non-diagonal inertia/damping matrices,"In this work, we investigate the state stabilization and trajectory tracking
+problems of underactuated surface ships with full state model of having
+non-diagonal inertia and damping matrices. By combining the novel state
+transformations, the direct Lyapunov approach, and the nonlinear time-varying
+tools, the stabilization and the trajectory tracking controllers are developed
+respectively guaranteeing global uniform asymptotic convergence of the state to
+the desired set point and global exponential convergence to the desired
+reference trajectory via mild persistent exciting conditions. Simulation
+examples are given to illustrate the effectiveness of the proposed control
+schemes.",1111.1029v1
+2011-11-08,The entropy of large black holes in loop quantum gravity: A combinatorics/analysis approach,"The issue of a possible damping of the entropy periodicity for large black
+holes in Loop Quantum Gravity is highly debated. Using a combinatorics/analysis
+approach, we give strong arguments in favor of this damping, at least for
+prescriptions where the projection constraint is not fully implemented. This
+means that black holes in loop gravity exhibit an asymptotic Bekenstein-Hawking
+behavior, provided that a consistent choice of the Immirzi constant is made.",1111.1975v1
+2011-11-15,Finite Size Effects of the Surface States in a Lattice Model of Topological Insulator,"Energy gap and wave function in thin films of topological insulator is
+studied, based on tight--binding model. It is revealed that thickness
+dependence of the magnitude of energy gap is composed of damping and
+oscillation. The damped behavior originates from the presence of gapless
+surface Dirac cone in the infinite thickness limit. On the other hand, the
+oscillatory behavior stems from electronic properties in the thin thickness
+limit.",1111.3528v2
+2011-11-23,Pumping the eccentricity of exoplanets by tidal effect,"Planets close to their host stars are believed to undergo significant tidal
+interactions, leading to a progressive damping of the orbital eccentricity.
+Here we show that, when the orbit of the planet is excited by an outer
+companion, tidal effects combined with gravitational interactions may give rise
+to a secular increasing drift on the eccentricity. As long as this secular
+drift counterbalances the damping effect, the eccentricity can increase to high
+values. This mechanism may explain why some of the moderate close-in exoplanets
+are observed with substantial eccentricity values.",1111.5486v1
+2011-11-30,Shear viscosity and damping of collective modes in a two-dimensional Fermi gas,"We compute the shear viscosity of a two dimensional Fermi gas interacting via
+a short range potential with scattering length $a_{2d}$ in kinetic theory. We
+find that kinetic theory predicts that the shear viscosity to entropy density
+ratio of a strongly interacting two dimensional gas is comparable to that of
+the three dimensional unitary gas. We use our results to compute the damping of
+collective modes in a trapped Fermi gas, and compare to experimental data
+recently obtained in E. Vogt et al., arXiv:1111.1173.",1111.7242v2
+2011-12-13,Drastically suppressing the error of ballistic readout of qubits,"The thermal jitter of transmission of magnetic flux quanta in long Josephson
+junctions is studied. While for large-to-critical damping and small values of
+bias current the physically obvious dependence of the jitter versus length
+$\sigma\sim\sqrt{L}$ is confirmed, for small damping starting from the
+experimentally relevant $\alpha=0.03$ and below strong deviation from
+$\sigma\sim\sqrt{L}$ is observed, up to nearly complete independence of the
+jitter versus length, which is exciting from fundamental point of view, but
+also intriguing from the point of view of possible applications.",1112.2805v1
+2011-12-15,Diffusion-Induced Oscillations of Extended Defects,"From a simple model for the driven motion of a planar interface under the
+influence of a diffusion field we derive a damped nonlinear oscillator equation
+for the interface position. Inside an unstable regime, where the damping term
+is negative, we find limit-cycle solutions, describing an oscillatory
+propagation of the interface. In case of a growing solidification front this
+offers a transparent scenario for the formation of solute bands in binary
+alloys, and, taking into account the Mullins-Sekerka instability, of banded
+structures.",1112.3669v1
+2012-01-03,Dynamics of DNA Bubble in Viscous Medium,"The damping effect to the DNA bubble is investigated within the
+Peyrard-Bishop model. In the continuum limit, the dynamics of the bubble of DNA
+is described by the damped nonlinear Schrodinger equation and studied by means
+of variational method. It is shown that the propagation of solitary wave
+pattern is not vanishing in a non-viscous system. Inversely, the solitary wave
+vanishes soon as the viscous force is introduced.",1201.0689v2
+2012-01-18,Magnetohydrodynamic Waves in Partially Ionized Prominence Plasmas,"Prominences or filaments are cool clouds of partially ionized plasma living
+in the solar corona. Ground- and space-based observations have confirmed the
+presence of oscillatory motions in prominences and they have been interpreted
+in terms of magnetohydrodynamic (MHD) waves. Existing observational evidence
+points out that these oscillatory motions are damped in short spatial and
+temporal scales by some still not well known physical mechanism(s). Since
+prominences are partially ionized plasmas, a potential mechanism able to damp
+these oscillations could be ion-neutral collisions. Here, we will review the
+work done on the effects of partial ionization on MHD waves in prominence
+plasmas.",1201.3752v1
+2012-01-30,Volatility-dependent damping of evaporation-driven Bénard-Marangoni instability,"The interface between a pure liquid and its vapor is usually close to
+saturation temperature, hence strongly hindering any thermocapillary flow. In
+contrast, when the gas phase contains an inert gas such as air,
+surface-tension-driven convection is easily observed. We here reconcile these
+two facts by studying the corresponding crossover experimentally, as a function
+of a new dimensionless number quantifying the degree of damping of interfacial
+temperature fluctuations. Critical conditions are in convincing agreement with
+a simple nonlocal one-sided model, in quite a range of evaporation rates.",1201.6334v1
+2012-02-18,Dynamics of multi-modes maximum entangled coherent state over amplitude damping channel,"The dynamics of maximum entangled coherent state travels through an amplitude
+damping channel is investigated. For small values of the transmissivity rate
+the travelling state is very fragile to this noise channel, where it suffers
+from the phase flip error with high probability. The entanglement decays
+smoothly for larger values of the transmissivity rate and speedily for smaller
+values of this rate. As the number of modes increases, the travelling state
+over this noise channel loses its entanglement hastily. The odd and even states
+vanish at the same value of the field intensity.",1202.4089v1
+2012-03-02,Damping-Antidamping Effect on Comets Motion,"We make an observation about Galilean transformation on a 1-D mass variable
+systems which leads us to the right way to deal with mass variable systems.
+Then using this observation, we study two-bodies gravitational problem where
+the mass of one of the bodies varies and suffers a damping-antidamping effect
+due to star wind during its motion. For this system, a constant of motion, a
+Lagrangian and a Hamiltonian are given for the radial motion, and the period of
+the body is studied using the constant of motion of the system. Our theoretical
+results are applied to Halley's comet.",1203.0495v2
+2012-03-03,Necessary and sufficient conditions of freezing phenomena of quantum discord under phase damping,"We investigate the freezing phenomenon of quantum discord occurring in phase
+damping noise processes. By relating the expression of the time variation of
+the discord to the convex function of relative entropy, we obtain the necessary
+and sufficient conditions of the phenomenon for standard Bell-diagonal states.
+These conditions are applicable also to the phenomenon occurring in a
+non-Markovian dephasing process. Moreover, we show that the same condition and
+phenomenon coincide in a new sort of Bell-diagonal states beyond the standard
+form.",1203.0650v3
+2012-03-06,Universal anomalous diffusion of weakly damped particles,"We show that anomalous diffusion arises in two different models for the
+motion of randomly forced and weakly damped particles: one is a generalisation
+of the Ornstein-Uhlenbeck process with a random force which depends on position
+as well as time, the other is a generalisation of the Chandrasekhar-Rosenbluth
+model of stellar dynamics, encompassing non-Coulombic potentials. We show that
+both models exhibit anomalous diffusion of position $x$ and momentum $p$ with
+the same exponents: $<x^2> \sim C_x t^2$ and $<p^2> \sim C_p t^{2/5}$. We are
+able to determine the prefactors $C_x$, $C_p$ analytically.",1203.1354v1
+2012-03-09,Collective Light Emission of a Finite Size Atomic Chain,"Radiative properties of collective electronic states in a one dimensional
+atomic chain are investigated. Radiative corrections are included with
+emphasize put on the effect of the chain size through the dependence on both
+the number of atoms and the lattice constant. The damping rates of collective
+states are calculated in considering radiative effects for different values of
+the lattice constant relative to the atomic transition wave length. Especially
+the symmetric state damping rate as a function of the number of the atoms is
+derived. The emission pattern off a finite linear chain is also presented. The
+results can be adopted for any chain of active material, e.g., a chain of
+semiconductor quantum dots or organic molecules on a linear matrix.",1203.2094v1
+2012-03-13,Monopoles in ferromagnetic metals,"The aim of this short review is to give an introduction to monopoles and to
+present theoretical derivation of two particular monopoles in ferromagnetic
+metals, a hedgehog monopole and a spin damping monopole. Spin damping monopoles
+can be generated in simple systems such as a junction of a ferromagnet and a
+heavy element with strong spin-orbit interaction such as Pt. This monopole is
+essential in coupling electronics with magnetism, and is thus expected to play
+an essential role in spintronics.",1203.2709v1
+2012-03-16,Report from KEK (High gradient study results from Nextef),"Most up-to-date high gradient test of the CLIC prototype structures as of
+September 2011 is described in this report. The ""T24"" undamped structure showed
+fast processing time, still-decreasing breakdown rate and its breakdown rate
+was estimated to be as low as the CLIC requirement. The ""TD24"" damped structure
+showed not so excellent high gradient performance as undamped ""T24"" but the
+characteristics was much improved than the damped ""TD18"" structure with higher
+magnetic field. Further R&D is needed and we present some of the present
+efforts at KEK.",1203.3626v1
+2012-03-30,Energy decay rates for solutions of the wave equation with linear damping in exterior domain,"In this paper we study the behavior of the energy of solutions of the wave
+equation with localized damping in exterior domain. We assume that the damper
+is positive at infinity. Under the Geometric Control Condition of Bardos et al
+(1992), we prove that: 1) The total energy decay like O(1/t) and L^2-norm is
+bounded for the solutions with initial data in (H_{0}^{1},L^{2}). 2) The total
+energy and the square of the L^2-norm, repectively, decay like O(1/t^{2}) and
+O(1/t) for a kind of the weighted initial data.",1203.6780v4
+2012-04-03,Modification in Silling's Peridynamic Formulation of Elasticity Theory for Discontinuities and Long-Range Forces,"We suggest modified version of Silling's peridynamic equation of motion
+within the framework of Silling's peridynamics formulation (J. Mech. Phys.
+Solids {\bf 48}, pp.175-209, 2000) of elasticity theory. The modified equation
+contains an additional damping force term. This term can eliminate artificial
+oscillations in displacement field at large values of time as predicted by
+Silling's peridynamic equation.",1204.0612v2
+2012-04-06,Experimental signatures of the quantum-classical transition in a nanomechanical oscillator modeled as a damped driven double-well problem,"We demonstrate robust and reliable signatures for the transition from quantum
+to classical behavior in the position probability distribution of a damped
+double-well system using the Qunatum State Diffusion approach to open quantum
+systems. We argue that these signatures are within experimental reach, for
+example in a doubly-clamped nanomechanical beam.",1204.1397v1
+2012-05-31,The impact of fill patterns on the fast ion instability in the ILC damping ring,"The ions produced via collisional ionization of the residual gas molecules in
+vacuum pipe with the circulating electron beam have deleterious effect on the
+beam properties and may become a limiting factor for the machine's performance.
+For the electron damping ring of the International Linear Collider (ILC), the
+ion instability is noticeable due to the ultra-low beam emittance with many
+bunches operation. In this paper, the different beam fill patterns are
+investigated and their effects on the fast ion instability are discussed. The
+simulations show that the mini train fill patterns can reduce the growth of the
+fast ion instability significantly.",1205.6977v1
+2012-06-11,Damping and decoherence of Fock states in a nanomechanical resonator due to two level systems,"We numerically investigate the decay of initial quantum Fock states and their
+superpositions for a mechanical resonator mode coupled to an environment
+comprising interacting, damped tunneling two level system (TLS) defects. The
+cases of one, three, and six near resonant, interacting TLS's are considered in
+turn and it is found that the resonator displays Ohmic bath like decay behavior
+with as few as three TLS's.",1206.2200v1
+2012-07-13,Magnetic relaxation in bilayers of yttrium iron garnet/platinum due to the dynamic coupling at the interface,"We show that in ferromagnetic (FM)/normal metal (NM) bilayers the dynamic
+coupling at the interface transfers an additional magnetic relaxation from the
+heavily damped motion of the conduction electron spins in the NM layer to the
+FM spins. While the FM relaxation rates due to two-magnon scattering and spin
+pumping decrease rapidly with increasing FM film thickness, the damping due to
+the dynamic coupling does not depend on the FM film thickness. The proposed
+mechanism explains the very large broadening of ferromagnetic resonance lines
+in thick films of yttrium iron garnet after deposition of a Pt layer.",1207.3330v1
+2012-07-23,Quantum interference induced by initial system-environment correlations,"We investigate the quantum interference induced by a relative phase in the
+correlated initial state of a system which consists in a two-level atom
+interacting with a damped mode of the radiation field. We show that the initial
+relative phase has significant effects on both the evolution of the atomic
+excited-state population and the information flow between the atom and the
+reservoir, as quantified by the trace distance. Furthermore, by considering two
+two-level atoms interacting with a common damped mode of the radiation field,
+we highlight how initial relative phases can affect the subsequent entanglement
+dynamics.",1207.5474v1
+2012-08-21,Dancing bunches as Van Kampen modes,"Van Kampen modes are eigen-modes of Jeans-Vlasov equation. Their spectrum
+consists of continuous and, possibly, discrete parts. Onset of a discrete van
+Kampen mode means emergence of a coherent mode without any Landau damping;
+thus, even a tiny couple-bunch wake is sufficient to drive instability.
+Longitudinal instabilities observed at Tevatron, RHIC and SPS can be explained
+as loss of Landau damping (LLD), which is shown here to happen at fairly low
+impedances. For repulsive wakes and single-harmonic RF, LLD is found to be
+extremely sensitive to steepness of the bunch distribution function at small
+amplitudes. Based on that, a method of beam stabilization is suggested.",1208.4338v1
+2012-08-22,Polynomial stabilization of some dissipative hyperbolic systems,"We study the problem of stabilization for the acoustic system with a
+spatially distributed damping. Imposing various hypotheses on the structural
+properties of the damping term, we identify either exponential or polynomial
+decay of solutions with growing time. Expo- nential decay rate is shown by
+means of a time domain approach, reducing the problem to an observability
+inequality to be verified for solutions of the associated conservative problem.
+In addition, we show a polynomial stabilization result, where the proof uses a
+frequency domain method and combines a contradiction argument with the
+multiplier technique to carry out a special analysis for the resolvent.",1208.4485v1
+2012-09-07,Quantum Damped Harmonic Oscillator,"In this chapter we treat the quantum damped harmonic oscillator, and study
+mathematical structure of the model, and construct general solution with any
+initial condition, and give a quantum counterpart in the case of taking
+coherent state as an initial condition.
+  This is a simple and good model of Quantum Mechanics with dissipation which
+is important to understand real world, and readers will get a powerful weapon
+for Quantum Physics.",1209.1437v1
+2012-10-08,"Comment on ""Thermal fluctuations of magnetic nanoparticles"" [arXiv:1209.0298]","We comment on some misleading and biased statements appearing in the
+manuscript arXiv:1209.0298 (""Thermal fluctuations of magnetic nanoparticles"")
+about the use of the damped Landau-Lifshitz equation and the kinetic Langer
+theory for the calculation of the relaxation rate of magnetic nanoclusters. We
+reiterate simple scientific arguments, part of which is well known to the whole
+community, demonstrating that the authors' criticisms are unfounded and that
+they overstate the issue of damping in the Landau-Lifshitz equation with no
+unanimous experimental evidence.",1210.2436v1
+2012-10-10,Phonon momentum and damping of mechanical resonators,"The concept of physical momentum associated to phonons in a crystal,
+complemented with some fundamental reasoning, implies measurable effects in
+crystals even at a macroscopic scale. We show that, in close analogy with the
+transfer of momentum in the kinetic theory of gases, physical momentum carried
+by of phonons couples the thermal and the velocity field in a vibrating
+crystal. Therefore an heat flow applied to a vibrating crystal can sustain or
+damp the oscillation, depending on the interplay between the temperature and
+the velocity gradient. We derive the general equations of this effect and show
+that its experimental confirmation is within reach of current technology.",1210.2847v1
+2012-10-12,HTS wiggler concept for a damping ring,"Magnetic design proposed for a damping ring (DR) is based on second
+generation HTS cabling technology applied to the DC windings with a yoke and
+mu-metal-shimmed pole to achieve ~2T high-quality field within a 86 mm gap and
+32-40 cm period. Low levels of current densities (~90-100A/mm2) provide a
+robust, reliable operation of the wiggler at higher heat loads, up to LN2
+temperatures with long leads, enhanced flexibility for the cryostats and
+infrastructure in harsh radiation environment, and reduced failure rate
+compared to the baseline SC ILC DR wiggler design at very competitive cost.",1210.3648v1
+2012-10-23,Dynamic response of open cell dry foams,"We study the mechanical response of an open cell dry foam subjected to
+periodic forcing using experiments and theory. Using the measurements of the
+static and dynamic stress-strain relationship, we derive an over-damped model
+of the foam, as a set of infinitesimal non-linear springs, where the damping
+term depends on the local foam strain. We then analyse the properties of the
+foam when subjected to large amplitudes periodic stresses and determine the
+conditions for which the foam becomes optimally absorbing.",1210.6229v1
+2012-10-31,Quantum discord of Bell cat-states under amplitude damping,"The evolution of pairwise quantum correlations of Bell cat-states under
+amplitude damping is examined using the concept of quantum discord which goes
+beyond entanglement. A closed expression of the quantum discord is explicitly
+derived. We used of the Koashi-Winter relation. A relation which facilitates
+the optimization process of the conditional entropy. We also discuss the
+temporal evolution of bipartite quantum correlations under a dephasing channel
+and compare the behaviors of quantum discord and entanglement whose properties
+are characterized through the concurrence.",1210.8309v1
+2012-10-31,Upsilon suppression in PbPb collisions at the LHC,"We suggest that the combined effect of screening, gluon-induced dissociation,
+collisional damping, and reduced feed-down explains most of the sequential
+suppression of Upsilon(nS) states that has been observed in PbPb relative to pp
+collisions at sqrt(s_NN) = 2.76 TeV. The suppression is thus a clear, albeit
+indirect, indication for the presence of a QGP. The Upsilon(1S) ground state
+suppression is essentially due to reduced feed-down, collisional damping and
+gluodissociation, whereas screening prevails for the suppression of the excited
+states.",1210.8366v2
+2012-11-04,The Threshold between Effective and Noneffective Damping for Semilinear Waves,"In this paper we study the global existence of small data solutions to the
+Cauchy problem for the semilinear wave equation with scale-invariant damping.
+We obtain estimates for the solution and its energy with the same decay rate of
+the linear problem. We extend our results to a model with polynomial speed of
+propagation and to a model with an exponential speed of propagation.",1211.0731v2
+2012-11-10,Heavy quark quenching from RHIC to LHC and the consequences of gluon damping,"In this contribution to the Quark Matter 2012 conference, we study whether
+energy loss models established for RHIC energies to describe the quenching of
+heavy quarks can be applied at LHC with the same success. We also benefit from
+the larger $p_T$-range accessible at this accelerator to test the impact of
+gluon damping on observables such as the nuclear modification factor.",1211.2281v1
+2012-11-30,Local feedback stabilisation to a non-stationary solution for a damped non-linear wave equation,"We study a damped semi-linear wave equation in a bounded domain with smooth
+boundary. It is proved that any sufficiently smooth solution can be stabilised
+locally by a finite-dimensional feedback control supported by a given open
+subset satisfying a geometric condition. The proof is based on an investigation
+of the linearised equation, for which we construct a stabilising control
+satisfying the required properties. We next prove that the same control
+stabilises locally the non-linear problem.",1211.7202v1
+2012-12-06,The physics of business cycles and inflation,"We analyse four consecutive cycles observed in the USA for employment and
+inflation. They are driven by three oil price shocks and an intended interest
+rate shock. Non-linear coupling between the rate equations for consumer
+products as prey and consumers as predators provides the required instability,
+but its natural damping is too high for spontaneous cycles. Extending the
+Lotka-Volterra equations with a small term for collective anticipation yields a
+second analytic solution without damping. It predicts the base period, phase
+shifts, and the sensitivity to shocks for all six cyclic variables correctly.",1212.1282v1
+2012-12-13,CMB Distortions from Damping of Acoustic Waves Produced by Cosmic Strings,"We study diffusion damping of acoustic waves in the photon-baryon fluid due
+to cosmic strings, and calculate the induced $\mu$- and $y$-type spectral
+distortions of the cosmic microwave background. For cosmic strings with tension
+within current bounds, their contribution to the spectral distortions is
+subdominant compared to the distortions from primordial density perturbations.",1212.3283v2
+2013-01-21,Asymptotic parabolicity for strongly damped wave equations,"For $S$ a positive selfadjoint operator on a Hilbert space, \[
+\frac{d^2u}{dt}(t) + 2 F(S)\frac{du}{dt}(t) + S^2u(t)=0 \] describes a class of
+wave equations with strong friction or damping if $F$ is a positive Borel
+function. Under suitable hypotheses, it is shown that \[ u(t)=v(t)+ w(t) \]
+where $v$ satisfies \[ 2F(S)\frac{dv}{dt}(t)+ S^2v(t)=0 \] and \[
+\frac{w(t)}{\|v(t)\|} \rightarrow 0, \; \text{as} \; t \rightarrow +\infty. \]
+The required initial condition $v(0)$ is given in a canonical way in terms of
+$u(0)$, $u'(0)$.",1301.4979v1
+2013-02-04,Gravity waves on the surface of topological superfluid 3He-B,"We have observed waves on the free surface of 3He-B sample at temperatures
+below 0.2mK. The waves are excited by vibrations of the cryostat and detected
+by coupling the surface to the Bose-Einstein condensate of magnon
+quasiparticles in the superfluid. The two lowest gravity-wave modes in our
+cylindrical container are identified. Damping of the waves increases with
+temperature linearly with the density of thermal quasiparticles, as expected.
+Additionally finite damping of the waves in the zero-temperature limit and
+enhancement of magnetic relaxation of magnon condensates by the surface waves
+are observed. We discuss whether the latter effects may be related to Majorana
+fermions bound to the surface of the topological superfluid.",1302.0764v1
+2013-02-12,On the fractional damped oscillators and fractional forced oscillators,"In this paper, we use the fractional calculus to discuss the fractional
+mechanics, where the time derivative is replaced with the fractional derivative
+of order $\nu$. We deal with the motion of a body in a resisting medium where
+the retarding force is assumed to be proportional to the fractional velocity
+which is obtained by acting the fractional derivative on the position. The
+fractional harmonic oscillator problem, fractional damped oscillator problem
+and fractional forced oscillator problem are also studied.",1302.2847v1
+2013-02-25,Optimal damping algorithm for unrestricted Hartree-Fock calculations,"We have developed a couple of optimal damping algorithms (ODAs) for
+unrestricted Hartree-Fock (UHF) calculations of open-shell molecular systems. A
+series of equations were derived for both concurrent and alternate
+constructions of alpha- and beta-Fock matrices in the integral-direct
+self-consistent-field (SCF) procedure. Several test calculations were performed
+to check the convergence behaviors. It was shown that the concurrent algorithm
+provides better performance than does the alternate one.",1302.6099v1
+2013-03-08,Entanglement of Open Quantum Systems in Noninertial Frames,"We study the effects of decoherence on the entanglement generated by Unruh
+effect in accelerated frames by using various combinations of an amplitude
+damping channel, a phase damping channel and a depolarizing channel in the form
+of multilocal and collective environments. Using concurrence as entanglement
+quantifier, we show that the occurrence of entanglement sudden death (ESD)
+depends on different combinations of the channels. The ESD can be avoided under
+a particular configuration of the channels. We show that the channels can be
+used to distinguish between a moving and a stationary frame.",1303.2034v1
+2013-03-21,Glued trees algorithm under phase damping,"We study the behaviour of the glued trees algorithm described by Childs et
+al. in [STOC `03, Proc. 35th ACM Symposium on Theory of Computing (2004) 59]
+under decoherence. We consider a discrete time reformulation of the continuous
+time quantum walk protocol and apply a phase damping channel to the coin state,
+investigating the effect of such a mechanism on the probability of the walker
+appearing on the target vertex of the graph. We pay particular attention to any
+potential advantage coming from the use of weak decoherence for the spreading
+of the walk across the glued trees graph.",1303.5319v2
+2013-04-04,Pais-Uhlenbeck Oscillator with a Benign Friction Force,"It is shown that the Pais-Uhlenbeck oscillator with damping, considered by
+Nesterenko, is a special case of a more general oscillator that has not only a
+first order, but also a third order friction term. If the corresponding damping
+constants, \alpha\ and \beta, are both positive and below certain critical
+values, then the system is stable. In particular, if \alpha = - \beta, then we
+have the unstable Nesterenko's oscillator",1304.1325v2
+2013-05-13,Guaranteed convergence of the Kohn-Sham equations,"A sufficiently damped iteration of the Kohn-Sham equations with the exact
+functional is proven to always converge to the true ground-state density,
+regardless of the initial density or the strength of electron correlation, for
+finite Coulomb systems. We numerically implement the exact functional for
+one-dimensional continuum systems and demonstrate convergence of the damped KS
+algorithm. More strongly correlated systems converge more slowly.",1305.2967v2
+2013-06-25,Decoherence effects in the quantum qubit flip game using Markovian approximation,"We are considering a quantum version of the penny flip game, whose
+implementation is influenced by the environment that causes decoherence of the
+system. In order to model the decoherence we assume Markovian approximation of
+open quantum system dynamics. We focus our attention on the phase damping,
+amplitude damping and amplitude raising channels. Our results show that the
+Pauli strategy is no longer a Nash equilibrium under decoherence. We attempt to
+optimize the players' control pulses in the aforementioned setup to allow them
+to achieve higher probability of winning the game compared to the Pauli
+strategy.",1306.5957v1
+2013-07-06,The 3-dimensional oscillon equation,"On a bounded three-dimensional smooth domain, we consider the generalized
+oscillon equation with Dirichlet boundary conditions, with time-dependent
+damping and time-dependent squared speed of propagation. Under structural
+assumptions on the damping and the speed of propagation, which include the
+relevant physical case of reheating phase of inflation, we establish the
+existence of a pullback global attractor of optimal regularity, and
+finite-dimensionality of the kernel sections.",1307.1777v1
+2013-08-30,"A conservative, skew-symmetric Finite Difference Scheme for the compressible Navier--Stokes Equations","We present a fully conservative, skew-symmetric finite difference scheme on
+transformed grids. The skew-symmetry preserves the kinetic energy by first
+principles, simultaneously avoiding a central instability mechanism and
+numerical damping. In contrast to other skew-symmetric schemes no special
+averaging procedures are needed. Instead, the scheme builds purely on
+point-wise operations and derivatives. Any explicit and central derivative can
+be used, permitting high order and great freedom to optimize the scheme
+otherwise. This also allows the simple adaption of existing finite difference
+schemes to improve their stability and damping properties.",1308.6672v1
+2013-09-09,Classical and quantum capacities of a fully correlated amplitude damping channel,"We study information transmission over a fully correlated amplitude damping
+channel acting on two qubits. We derive the single-shot classical channel
+capacity and show that entanglement is needed to achieve the channel best
+performance. We discuss the degradability properties of the channel and
+evaluate the quantum capacity for any value of the noise parameter. We finally
+compute the entanglement-assisted classical channel capacity.",1309.2219v3
+2013-09-13,Polarization hydrodynamics in a one-dimensional polariton condensate,"We study the hydrodynamics of a nonresonantly-pumped polariton condensate in
+a quasi-one-dimensional quantum wire taking into account the spin degree of
+freedom. We clarify the relevance of the Landau criterion for superfluidity in
+this dissipative two-component system. Two Cherenkov-like critical velocities
+are identified corresponding to the opening of different channels of radiation:
+one of (damped) density fluctuations and another of (weakly damped)
+polarization fluctuations. We determine the drag force exerted onto an external
+obstacle and propose experimentally measurable consequences of the specific
+features of the fluctuations of polarization.",1309.3494v1
+2013-09-26,Imperfect geometric control and overdamping for the damped wave equation,"We consider the damped wave equation on a manifold with imperfect geometric
+control. We show the sub-exponential energy decay estimate in
+\cite{Chr-NC-erratum} is optimal in the case of one hyperbolic periodic
+geodesic. We show if the equation is overdamped, then the energy decays
+exponentially. Finally we show if the equation is overdamped but geometric
+control fails for one hyperbolic periodic geodesic, then nevertheless the
+energy decays exponentially.",1309.6967v1
+2013-10-01,Scalar filed evolution and area spectrum for Lovelock-AdS black holes,"We study the modes of evolution of massless scalar fields in the
+asymptotically AdS spacetime surrounding maximally symmetric black holes of
+large and intermediate size in the Lovelock model. It is observed that all
+modes are purely damped at higher orders. Also, the rate of damping is seen to
+be independent of order at higher dimensions. The asymptotic form of these
+frequencies for the case of large black holes is found analytically. Finally,
+the area spectrum for such black holes is found from these asymptotic modes.",1310.0159v2
+2013-10-16,Perturbative quantum damping of cosmological expansion,"Perturbative quantum gravity in the framework of the Schwinger-Keldysh
+formalism is applied to compute lowest-order corrections to the actual
+expansion of the Universe described in terms of the spatially flat
+Friedman-Lematre-Robertson-Walker solution. The classical metric is
+approximated by a third order polynomial perturbation around the Minkowski
+metric. It is shown that the quantum contribution to the classical expansion,
+although extremely small, has damping properties (quantum friction), i.e. it
+slows down the expansion.",1310.4308v2
+2013-10-27,Loss of non-Gaussianity for damped photon-subtracted thermal states,"We investigate non-Gaussianity properties for a set of classical one-mode
+states obtained by subtracting photons from a thermal state. Three
+distance-type degrees of non-Gaussianity used for these states are shown to
+have a monotonic behaviour with respect to their mean photon number. Decaying
+of their non-Gaussianity under damping is found to be consistently described by
+the distance-type measures considered here. We also compare the dissipative
+evolution of non-Gaussianity when starting from $M$-photon-subtracted and
+$M$-photon-added thermal states",1310.7229v1
+2013-10-27,Landau damping effects and evolutions of energy spread in small isochronous ring,"This paper presents the Landau damping effects on the microwave instability
+of a coasting long bunch in an isochronous ring due to finite energy spread and
+emittance. Our two-dimensional (2D) dispersion relation gives more accurate
+predictions of the microwave instability growth rates of short-wavelength
+perturbations than the conventional 1D formula. The long-term evolution of
+energy spread is also studied by measurements and simulations.",1310.7253v3
+2013-10-28,Robustness of multiparticle entanglement: specific entanglement classes and random states,"We investigate the robustness of genuine multiparticle entanglement under
+decoherence. We consider different kinds of entangled three- and four-qubit
+states as well as random pure states. For amplitude damping noise, we find that
+the W-type states are most robust, while other states are not more robust than
+generic states. For phase damping noise the GHZ state is the most robust state,
+and for depolarizing noise several states are significantly more robust than
+random states.",1310.7336v2
+2013-11-22,Complexity of the minimum-time damping of a physical pendulum,"We study the minimum-time damping of a physical pendulum by means of a
+bounded control. In the similar problem for a linear oscillator each optimal
+trajectory possesses a finite number of control switchings from the maximal to
+the minimal value. If one considers simultaneously all optimal trajectories
+with any initial state, the number of switchings can be arbitrary large. We
+show that for the nonlinear pendulum there is a uniform bound for the switching
+number for all optimal trajectories. We find asymptotics for this bound as the
+control amplitude goes to zero.",1311.5729v1
+2013-12-16,Local Energy Decay for the Damped Wave Equation,"We prove local energy decay for the damped wave equation on R^d. The problem
+which we consider is given by a long range metric perturbation of the Euclidean
+Laplacian with a short range absorption index. Under a geometric control
+assumption on the dissipation we obtain an almost optimal polynomial decay for
+the energy in suitable weighted spaces. The proof relies on uniform estimates
+for the corresponding ""resolvent"", both for low and high frequencies. These
+estimates are given by an improved dissipative version of Mourre's commutators
+method.",1312.4483v1
+2013-12-23,Photonic tuning of quasi-particle decay in a superfluid,"We show that the damping rate of elementary excitations of hybrid systems
+close to a phase transition can undergo a remarkable resonance like enhancement
+before mode softening takes place. In particular, we consider the friction of a
+collective density wave in a homogeneous superfluid of weakly interacting
+bosonic atoms coupled to the electromagnetic field of a single mode optical
+resonator. Here the Beliaev damping can thus be controlled by an external laser
+drive and be enhanced by several orders of magnitude.",1312.6719v1
+2014-01-04,Entanglement and quantum teleportation via decohered tripartite entangled states,"The entanglement behavior of two classes of multi-qubit system, GHZ and GHZ
+like states passing through a generalized amplitude damping channel is
+discussed. Despite this channel causes degradation of the entangled properties
+and consequently their abilities to perform quantum teleportation, one can
+always improve the lower values of the entanglement and the fidelity of the
+teleportrd state by controlling on Bell measurements, analyzer angle and
+channel's strength. Using GHZ-like state within a generalized amplitude damping
+channel is much better than using the normal GHZ-state, where the decay rate of
+entanglement and the fidelity of the teleported states are smaller than those
+depicted for GHZ state.",1401.0796v1
+2014-02-11,New approach for Damping in a squeezed bath and its time evolution through Complete Class of Gaussian Quasi-distributions,"By virtue of the thermal entangled states representation of density operator
+and using dissipative interaction picture we solve the master equation of a
+driven damped harmonic oscillator in a squeezed bath. We show that the
+essential part of the dynamics can be expressed by the convolution of initial
+Wigner function with a special kind of normalized Gaussian in phase space and
+relate the dynamics with the change of Gaussian ordering of density operator.",1402.2545v1
+2014-02-11,New approach for solving master equations of density operator for the Jaynes Cummings Model with Cavity Damping,"By introducing thermal entangled state representation which can map master
+equations of density operator in quantum statistics as state vector evolution
+equations and using dissipative interaction picture we solve the master
+equation of J-C model with cavity damping. In addition we derive the Wigner
+function for density operator when the atom is initially in the up state and
+the cavity mode is in coherent state.",1402.2556v1
+2014-02-19,Superfluid Bloch dynamics in an incommensurate lattice,"We investigate the interplay of disorder and interactions in the accelerated
+transport of a Bose-Einstein condensate through an incommensurate optical
+lattice. We show that interactions can effectively cancel the damping of Bloch
+oscillations due to the disordered potential and we provide a simple model to
+qualitatively capture this screening effect. We find that the characteristic
+interaction energy, above which interactions and disorder cooperate to enhance,
+rather than reduce, the damping of Bloch oscillations, coincides with the
+average disorder depth. This is consistent with results of a mean-field
+simulation.",1402.4830v1
+2014-02-21,Weakly damped acoustic plasmon mode in transition metal dichalcogenides with Zeeman splitting,"We analyze the effect of a strong Zeeman field on the spectrum of collective
+excitations of monolayer transition metal dichalcogenides. The combination of
+the Dresselhaus type spin orbit coupling and an external Zeeman field result in
+the lifting of the valley degeneracy in the valence band of these crystals. We
+show that this lifting of the valley degeneracy manifests in the appearance of
+an additional plasmon mode with linear in wavenumber dispersion along with the
+standard square root in wavenumber mode. Despite this novel mode being subject
+to the Landau damping, it corresponds to a well defined quasiparticle peak in
+the spectral function of the electron gas.",1402.5274v1
+2014-04-18,"On the Instability and Critical Damping Conditions, $kτ= 1/e$ and $kτ= π/2$ of the equation $\dotθ = -k θ(t-τ)$","In this note, I show that it is possible to use elementary mathematics,
+instead of the machinery of Lambert function, Laplace Transform, or numerics,
+to derive the instability condition, $k \tau = \pi/2$, and the critical damping
+condition, $k\tau = 1/e$, for the time-delayed equation $\dot{\theta} = -k
+\theta(t-\tau)$. I hope it will be useful for the new comers to this equation,
+and perhaps even to the experts if this is a simpler method compared to other
+versions.",1404.4763v1
+2014-04-22,Nonlinear-damped Duffing oscillators having finite time dynamics,"A class of modified Duffing oscillator differential equations, having
+nonlinear damping forces, are shown to have finite time dynamics, i.e., the
+solutions oscillate with only a finite number of cycles, and, thereafter, the
+motion is zero. The relevance of this feature is briefly discussed in
+relationship to the mathematical modeling, analysis, and estimation of
+parameters for the vibrations of carbon nano-tubes and graphene sheets, and
+macroscopic beams and plates.",1404.5596v1
+2014-05-01,On the collapse of trial solutions for a damped-driven non-linear Schrödinger equation,"We consider the focusing 2D non-linear Schr\""odinger equation, perturbed by a
+damping term, and driven by multiplicative noise. We show that a physically
+motivated trial solution does not collapse for any admissible initial condition
+although the exponent of the non-linearity is critical. Our method is based on
+the construction of a global solution to a singular stochastic Hamiltonian
+system used to connect trial solution and Schr\""odinger equation.",1405.0151v3
+2014-05-02,Dynamic phase diagram of dc-pumped magnon condensates,"We study the effects of nonlinear dynamics and damping by phonons on a system
+of interacting electronically pumped magnons in a ferromagnet. The nonlinear
+effects are crucial for constructing the dynamic phase diagram, which describes
+how ""swasing"" and Bose-Einstein condensation emerge out of the
+quasiequilibrated thermal cloud of magnons. We analyze the system in the
+presence of magnon damping and interactions, demonstrating the continuous onset
+of stable condensates as well as hysteretic transitions.",1405.0522v1
+2014-05-05,Finite time extinction for nonlinear Schrodinger equation in 1D and 2D,"We consider a nonlinear Schrodinger equation with power nonlinearity, either
+on a compact manifold without boundary, or on the whole space in the presence
+of harmonic confinement, in space dimension one and two. Up to introducing an
+extra superlinear damping to prevent finite time blow up, we show that the
+presence of a sublinear damping always leads to finite time extinction of the
+solution in 1D, and that the same phenomenon is present in the case of small
+mass initial data in 2D.",1405.0995v1
+2014-05-16,Investigation of Power-Law Damping/Dissipative Forces,"The properties of a one space-dimension, one particle dynamical system under
+the influence of a purely dissipative force are investigated. Assuming this
+force depends only on the velocity, it is demonstrated, in contrast to the case
+of linear damping, that there exist dissipative forces for which the particle
+\textquotedblleft stops"" in a finite time. It is also shown, by an explicit
+example, that other dissipative forces exist such that they produce dynamics in
+which the particle achieves zero velocity only after an infinite distance has
+been traveled. Possible applications of these results to more complex
+situations are discussed.",1405.4062v1
+2014-06-02,"Nonlinear coupler operating on Werner-like states - entanglement creation, its enhancement and preservation","We discuss a model of two nonlinear Kerr-like oscillators, mutually coupled
+and excited by parametric process. We show that the system's evolution,
+starting from Werner-like states, remains closed within a small set of two-mode
+n-photon states the system, and pure two-qubit entangled state can be
+generated. For some initial Werner-like states delayed entanglement generation
+can be observed. We investigate the influence of two damping mechanisms on the
+system's evolution. We show that for the both cases, the entanglement can
+survive despite the presence of damping, and the effects of sudden entanglement
+death and its rebirth can appear in the system.",1406.0414v1
+2014-06-10,A determining form for the damped driven Nonlinear Schrödinger Equation- Fourier modes case,"In this paper we show that the global attractor of the 1D damped, driven,
+nonlinear Schr\""odinger equation (NLS) is embedded in the long-time dynamics of
+a determining form. The determining form is an ordinary differential equation
+in a space of trajectories $X=C_b^1(\mathbb{R}, P_mH^2)$ where $P_m$ is the
+$L^2$-projector onto the span of the first $m$ Fourier modes. There is a
+one-to-one identification with the trajectories in the global attractor of the
+NLS and the steady states of the determining form. We also give an improved
+estimate for the number of the determining modes.",1406.2626v1
+2014-08-20,Initial Layer and Relaxation Limit of Non-Isentropic Compressible Euler Equations with Damping,"In this paper, we study the relaxation limit of the relaxing Cauchy problem
+for non-isentropic compressible Euler equations with damping in
+multi-dimensions. We prove that the velocity of the relaxing equations
+converges weakly to that of the relaxed equations, while other variables of the
+relaxing equations converges strongly to the corresponding variables of the
+relaxed equations. We show that as relaxation time approaches 0, there exists
+an initial layer for the ill-prepared data, the convergence of the velocity is
+strong outside the layer; while there is no initial layer for the well-prepared
+data, the convergence of the velocity is strong near t=0.",1408.4784v1
+2014-08-26,Exponential decay for the damped wave equation in unbounded domains,"We study the decay of the semigroup generated by the damped wave equation in
+an unbounded domain. We first prove under the natural geometric control
+condition the exponential decay of the semigroup. Then we prove under a weaker
+condition the logarithmic decay of the solutions (assuming that the initial
+data are smoother). As corollaries, we obtain several extensions of previous
+results of stabilisation and control.",1408.6054v2
+2014-10-03,Relaxation of regularity for the Westervelt equation by nonlinear damping with application in acoustic-acoustic and elastic-acoustic coupling,"In this paper we show local (and partially global) in time existence for the
+Westervelt equation with several versions of nonlinear damping. This enables us
+to prove well-posedness with spatially varying $L_\infty$-coefficients, which
+includes the situation of interface coupling between linear and nonlinear
+acoustics as well as between linear elasticity and nonlinear acoustics, as
+relevant, e.g., in high intensity focused ultrasound (HIFU) applications.",1410.0797v1
+2014-10-13,Vortex gyration mediated by spin waves driven by an out-of-plane oscillating magnetic field,"In this letter we address the vortex core dynamics involved in gyration
+excitation and damping change by out-of-plane oscillating magnetic fields. When
+the vortex core is at rest under the effect of in-plane bias magnetic fields,
+the spin waves excited by the perpendicular magnetic field can induce obvious
+vortex gyration. When simultaneously excite spin waves and vortex gyrotropic
+motion, the gyration damping changes. Analysis of the system energy allows us
+to explain the origin of the spin-wave-mediated vortex gyration.",1410.3230v1
+2014-10-23,Non-equilibrium thermodynamics approach to open quantum systems,"Open quantum systems are studied from the thermodynamical point of view
+unifying the principle of maximum informational entropy and the hypothesis of
+relaxation times hierarchy. The result of the unification is a non-Markovian
+and local in time master equation that provides a direct connection of
+dynamical and thermodynamical properties of open quantum systems. The power of
+the approach is illustrated with the application to the damped harmonic
+oscillator and the damped driven two-level system resulting in analytical
+expressions for the non-Markovian and non-equilibrium entropy and inverse
+temperature.",1410.6312v2
+2014-10-27,Linear Inviscid Damping for Monotone Shear Flows,"In this article, we prove linear stability, scattering and inviscid damping
+with optimal decay rates for the linearized 2D Euler equations around a large
+class of strictly monotone shear flows, $(U(y),0)$, in a periodic channel under
+Sobolev perturbations. Here, we consider the settings of both an infinite
+periodic channel of period $L$, $\mathbb{T}_{L}\times \mathbb{R}$, as well as a
+finite periodic channel, $\mathbb{T}_{L} \times [0,1]$, with impermeable walls.
+The latter setting is shown to not only be technically more challenging, but to
+exhibit qualitatively different behavior due to boundary effects.",1410.7341v2
+2014-11-08,Damping of liquid sloshing by foams: from everyday observations to liquid transport,"We perform experiments on the sloshing dynamics of liquids in a rectangular
+container submitted to an impulse. We show that when foam is placed on top of
+the liquid the oscillations of the free interface are significantly damped. The
+ability to reduce sloshing and associated splashing could find applications in
+numerous industrial processes involving liquid transport.",1411.2123v1
+2014-11-17,A geometric mesh smoothing algorithm related to damped oscillations,"We introduce a smoothing algorithm for triangle, quadrilateral, tetrahedral
+and hexahedral meshes whose centerpiece is a simple geometric triangle
+transformation. The first part focuses on the mathematical properties of the
+element transformation. In particular, the transformation gives rise directly
+to a continuous model given by a system of coupled damped oscillations. Derived
+from this physical model, adaptive parameters are introduced and their benefits
+presented. The second part discusses the mesh smoothing algorithm based on the
+element transformation and its numerical performance on example meshes.",1411.4390v3
+2014-12-05,Exponential dephasing of oscillators in the Kinetic Kuramoto Model,"We study the kinetic Kuramoto model for coupled oscillators with coupling
+constant below the synchronization threshold. We manage to prove that, for any
+analytic initial datum, if the interaction is small enough, the order parameter
+of the model vanishes exponentially fast, and the solution is asymptotically
+described by a free flow. This behavior is similar to the phenomenon of Landau
+damping in plasma physics. In the proof we use a combination of techniques from
+Landau damping and from abstract Cauchy-Kowalewskaya theorem.",1412.1923v1
+2014-12-23,Selftrapping triggered by losses in cavity QED,"In a coupled cavity QED network model, we study the transition from a
+localized super fluid like state to a delocalized Mott insulator like state,
+triggered by losses. Without cavity losses, the transition never takes place.
+Further, if one measures the quantum correlations between the polaritons via
+the negativity, we find a critical cavity damping constant, above which the
+negativity displays a single peak in the same time region where the transition
+takes place. Additionally, we identify two regions in the parameter space,
+where below the critical damping, oscillations of the initial localized state
+are observed along with a multipeaked negativity, while above the critical
+value, the oscillations die out and the transition is witnessed by a neat
+single peaked negativity.",1412.7495v1
+2015-01-07,Two-photon lasing by a superconducting qubit,"We study the response of a magnetic-field-driven superconducting qubit
+strongly coupled to a superconducting coplanar waveguide resonator. We observed
+a strong amplification/damping of a probing signal at different resonance
+points corresponding to a one and two-photon emission/absorption. The sign of
+the detuning between the qubit frequency and the probe determines whether
+amplification or damping is observed. The larger blue detuned driving leads to
+two-photon lasing while the larger red detuning cools the resonator. Our
+experimental results are in good agreement with the theoretical model of qubit
+lasing and cooling at the Rabi frequency.",1501.01543v1
+2015-02-02,Enhanced oscillation lifetime of a Bose-Einstein condensate in the 3D/1D crossover,"We have measured the damped motion of a trapped Bose-Einstein condensate,
+oscillating with respect to a thermal cloud. The cigar-shaped trapping
+potential provides enough transverse confinement that the dynamics of the
+system are intermediate between three-dimensional and one-dimensional. We find
+that oscillations persist for longer than expected for a three-dimensional gas.
+We attribute this to the suppressed occupation of transverse momentum states,
+which are essential for damping.",1502.00430v2
+2015-02-03,Nonequilibrium dynamics of an ultracold dipolar gas,"We study the relaxation and damping dynamics of an ultracold, but not quantum
+degenerate, gas consisting of dipolar particles. These simulations are
+performed using a direct simulation Monte Carlo method and employing the highly
+anisotropic differential cross section of dipoles in the Wigner threshold
+regime. We find that both cross-dimensional relaxation and damping of breathing
+modes occur at rates that are strongly dependent on the orientation of the
+dipole moments relative to the trap axis. The relaxation simulations are in
+excellent agreement with recent experimental results in erbium. The results
+direct our interest toward a less explored regime in dipolar gases where
+interactions are dominated by collision processes rather than mean-field
+interactions.",1502.00960v1
+2015-02-01,"On the Stability of Cylindrical Tangential Discontinuity, Generation and Damping of Helical Waves","Stability of cylindrical interface between two ideal incompressible fluids,
+including the magnetic field, surface tension and gravitational field is
+studied in linear approximation. We found that helical waves arising both in
+plasma comet tails and on the vertical cylindrical water jet in the air are
+described by the same dispersion equation where the comet tail magnetic field
+plays the same stabilizing role as surface tension for water jet. Hence they
+represent the same phenomenon of Kelvin-Helmholtz instability. Thus helical
+waves in comet tails and astrophysical jets may be simulated in the laboratory.
+The resonance nature of the Kelvin- instability damping is demonstrated.",1502.00989v1
+2015-03-04,On the Lewis-Riesenfeld (Dodonov-Man'ko) invariant method,"We revise the Lewis-Riesenfeld invariant method for solving the quantum
+time-dependent harmonic oscillator in light of the Quantum Arnold
+Transformation previously introduced and its recent generalization to the
+Quantum Arnold-Ermakov-Pinney Transformation. We prove that both methods are
+equivalent and show the advantages of the Quantum Arnold-Ermakov-Pinney
+transformation over the Lewis-Riesenfeld invariant method. We show that, in the
+quantum time-dependent and damped harmonic oscillator, the invariant proposed
+by Dodonov & Man'ko is more suitable and provide some examples to illustrate
+it, focusing on the damped case.",1503.01371v1
+2015-03-06,On the strongly damped wave equation with constraint,"A weak formulation for the so-called ""semilinear strongly damped wave
+equation with constraint"" is introduced and a corresponding notion of solution
+is defined. The main idea in this approach consists in the use of duality
+techniques in Sobolev-Bochner spaces, aimed at providing a suitable
+""relaxation"" of the constraint term. A global in time existence result is
+proved under the natural condition that the initial data have finite ""physical""
+energy.",1503.01911v1
+2015-03-23,Spin-Orbit Torques in Two-Dimensional Rashba Ferromagnets,"Magnetization dynamics in single-domain ferromagnets can be triggered by
+charge current if spin-orbit coupling is sufficiently strong. We apply
+functional Keldysh theory to investigate Rashba spin-orbit torques in metallic
+two-dimensional ferromagnets. A reactive, anti-damping-like spin-orbit torque
+as well as a dissipative, field-like torque are calculated microscopically, to
+the leading order in the spin-orbit interaction strength. By calculating the
+first vertex correction we show that the intrinsic anti-damping-like torque
+vanishes unless the scattering rates are spin-dependent.",1503.06872v2
+2015-04-18,Global Dirichlet Heat Kernel Estimates for Symmetric Lévy Processes in Half-space,"In this paper, we derive explicit sharp two-sided estimates for the Dirichlet
+heat kernels of a large class of symmetric (but not necessarily rotationally
+symmetric) L\'evy processes on half spaces for all $t>0$. These L\'evy
+processes may or may not have Gaussian component. When L\'evy density is
+comparable to a decreasing function with damping exponent $\beta$,our estimate
+is explicit in terms of the distance to the boundary, the L\'evy exponent and
+the damping exponent $\beta$ of L\'evy density.",1504.04673v2
+2015-05-05,The transition from the classical to the quantum regime in nonlinear Landau damping,"Starting from the Wigner-Moyal equation coupled to Poisson's equation, a
+simplified set of equations describing nonlinear Landau damping of Langmuir
+waves is derived. This system is studied numerically, with a particular focus
+on the transition from the classical to the quantum regime. In the quantum
+regime several new features are found. This includes a quantum modified bounce
+frequency, and the discovery that bounce-like amplitude oscillations can take
+place even in the absence of trapped particles. The implications of our results
+are discussed.",1505.01381v1
+2015-05-08,The amplification of weak measurements under quantum noise,"The influence of outside quantum noises on the amplification of weak
+measurements is investigated. Three typical quantum noises are discussed. The
+maximum values of the pointer's shifts decrease sharply with the strength of
+the depolarizing channel and phase damping. In order to obtain significant
+amplified signals, the preselection quantum systems must be kept away from the
+two quantum noises. Interestingly, the amplification effect is immune to the
+amplitude damping noise.",1505.01911v1
+2015-05-27,Local energy decay and smoothing effect for the damped Schr{ö}dinger equation,"We prove the local energy decay and the smoothing effect for the damped
+Schr{\""o}dinger equation on R^d. The self-adjoint part is a Laplacian
+associated to a long-range perturbation of the flat metric. The proofs are
+based on uniform resolvent estimates obtained by the dissipative Mourre method.
+All the results depend on the strength of the dissipation which we consider.",1505.07200v1
+2015-06-01,Local decay for the damped wave equation in the energy space,"We improve a previous result about the local energy decay for the damped wave
+equation on R^d. The problem is governed by a Laplacian associated with a long
+range perturbation of the flat metric and a short range absorption index. Our
+purpose is to recover the decay O(t^{--d+$\epsilon$}) in the weighted energy
+spaces. The proof is based on uniform resolvent estimates, given by an improved
+version of the dissipative Mourre theory. In particular we have to prove the
+limiting absorption principle for the powers of the resolvent with inserted
+weights.",1506.00377v1
+2015-06-03,Giant Phonon Anomaly associated with Superconducting Fluctuations in the Pseudogap Phase of Cuprates,"The opening of the pseudogap in underdoped cuprates breaks up the Fermi
+surface, which may lead to a breakup of the d-wave order parameter into two
+subband amplitudes and a low energy Leggett mode due to phase fluctuations
+between them. This causes a large increase in the temperature range of
+superconducting fluctuations with an overdamped Leggett mode. Almost resonant
+scattering of inter-subband phonons to a state with a pair of Leggett modes
+causes anomalously strong damping. In the ordered state, the Leggett mode
+develops a finite energy, suppressing the anomalous phonon damping but leading
+to an anomaly in the phonon dispersion.",1506.01258v1
+2015-06-06,On higher regularity for the Westervelt equation with strong nonlinear damping,"We show higher interior regularity for the Westervelt equation with strong
+nonlinear damping term of the $q$-Laplace type. Secondly, we investigate an
+interface coupling problem for these models, which arise, e.g., in the context
+of medical applications of high intensity focused ultrasound in the treatment
+of kidney stones. We show that the solution to the coupled problem exhibits
+piecewise $H^2$ regularity in space, provided that the gradient of the acoustic
+pressure is essentially bounded in space and time on the whole domain. This
+result is of importance in numerical approximations of the present problem, as
+well as in gradient based algorithms for finding the optimal shape of the
+focusing acoustic lens in lithotripsy.",1506.02125v1
+2015-06-08,Intermode-coupling modulation in the fermion-boson model: heating effects in the BCS regime,"Heating induced by an oscillating modulation of the interaction strength in
+an atomic Fermion pair condensate is analyzed. The coupled fermion-boson model,
+generalized by incorporating a time-dependent intermode coupling through a
+magnetic Feshbach resonance, is applied. The dynamics is analytically
+characterized in a perturbative scheme. The results account for experimental
+findings which have uncovered a damped and delayed response of the condensate
+to the modulation. The delay is due to the variation of the quasiparticle
+energies and the subsequent relaxation of the condensate. The detected damping
+results from the excitations induced by a nonadiabatic modulation: for driving
+frequencies larger than twice the pairing gap, quasiparticles are generated,
+and, consequently, heating sets in.",1506.02612v1
+2015-06-22,N-body description of Debye shielding and Landau damping,"This paper brings further insight into the recently published N-body
+description of Debye shielding and Landau damping [Escande D F, Elskens Y and
+Doveil F 2014 Plasma Phys. Control. Fusion 57 025017]. Its fundamental equation
+for the electrostatic potential is derived in a simpler and more rigorous way.
+Various physical consequences of the new approach are discussed, and this
+approach is compared with the seminal one by Pines and Bohm [Pines D and Bohm D
+1952 Phys. Rev. 85 338--353].",1506.06468v2
+2015-07-23,Millisecond newly born pulsars as efficient accelerators of electrons,"The newly born millisecond pulsars are investigated as possible energy
+sources for creating ultra-high energy electrons. The transfer of energy from
+the star rotation to high energy electrons takes place through the Landau
+damping of centrifugally driven (via a two stream instability) electrostatic
+Langmuir waves. Generated in the bulk magnetosphere plasma, such waves grow to
+high amplitudes, and then damp, very effectively, on relativistic electrons
+driving them to even higher energies. We show that the rate of transfer of
+energy is so efficient that no energy losses might affect the mechanism of
+particle acceleration; the electrons might achieve energies of the order of
+10^{18}eV for parameters characteristic of a young star.",1507.06415v1
+2015-07-28,Stability of solutions to nonlinear wave equations with switching time-delay,"In this paper we study well-posedness and asymptotic stability for a class of
+nonlinear second-order evolution equations with intermittent delay damping.
+More precisely, a delay feedback and an undelayed one act alternately in time.
+We show that, under suitable conditions on the feedback operators, asymptotic
+stability results are available. Concrete examples included in our setting are
+illustrated. We give also stability results for an abstract model with
+alternate positive-negative damping, without delay.",1507.07787v1
+2015-08-10,Theory of the strongly-damped quantum harmonic oscillator,"We analyse the properties of a strongly-damped quantum harmonic oscillator by
+means of an exact diagonalisation of the full Hamiltonian, including both the
+oscillator and the reservoir degrees of freedom to which it is coupled. Many of
+the properties of the oscillator, including its steady-state properties and
+entanglement with the reservoir can be understood and quantified in terms of a
+simple probability density, which we may associate with the ground-state
+frequency spectrum of the oscillator.",1508.02442v1
+2015-08-20,Bump-on-tail instability of twisted excitations in rotating cold atomic clouds,"We develop a kinetic theory for twisted density waves (phonons), carrying a
+finite amount of orbital angular momentum, in large magneto optical traps,
+where the collective processes due to the exchange of scattered photons are
+considered. Explicit expressions for the dispersion relation and for the
+kinetic (Landau) damping are derived and contributions from the orbital angular
+momentum are discussed. We show that for rotating clouds, exhibiting
+ring-shaped structures, phonons carrying orbital angular momentum can cross the
+instability threshold and grow out of noise, while the usual plane wave
+solutions are kinetically damped.",1508.05127v1
+2015-09-30,Approximation of Invariant Measure for Damped Stochastic Nonlinear Schrödinger Equation via an Ergodic Numerical Scheme,"In order to inherit numerically the ergodicity of the damped stochastic
+nonlinear Schr\""odinger equation with additive noise, we propose a fully
+discrete scheme, whose spatial direction is based on spectral Galerkin method
+and temporal direction is based on a modification of the implicit Euler scheme.
+We not only prove the unique ergodicity of the numerical solutions of both
+spatial semi-discretization and full discretization, but also present error
+estimations on invariant measures, which gives order $2$ in spatial direction
+and order ${\frac12}$ in temporal direction.",1509.09148v2
+2015-10-02,Cavity and HOM Coupler Design for CEPC,"In this paper we will show a cavity and higher order mode (HOM) coupler
+designing scheme for the Circular Electron-Positron Collider (CEPC) main ring.
+The cavity radio frequency (RF) design parameters are showed in this paper. The
+HOM power is calculated based on the beam parameters in the Preliminary
+Conceptual Design Report (Pre-CDR). The damping results of the higher order
+modes (HOMs) and same order modes (SOMs) show that they are reached the damping
+requirements for beam stability.",1510.00467v1
+2015-11-08,Upper semicontinuity of pullback attractors for damped wave equations,"In this paper, we study the upper semicontinuity of pullback attractors for a
+strongly damped wave equation. In particular, under some proper assumptions, we
+prove that, the pullback attractor $\{A_\varepsilon(t)\}_{t\in\mathbb R}$} of
+Eq.(1.1) with $\varepsilon\in[0,1]$ satisfies that for any $[a,b]\subset\mathbb
+R$ and $\varepsilon_0\in[0,1]$, $\lim_{\varepsilon\to\varepsilon_0}
+\sup_{t\in[a,b]} \mathrm{dist}_{H_0^1\times L^2} (A_\varepsilon(t),
+A_{\varepsilon_0}(t))=0$, and $\cup_{t\in[a,b]} \cup_{\varepsilon\in[0,1]}
+A_\varepsilon(t)$ is precompact in $H_0^1 (\Omega) \times L^2(\Omega)$.",1511.02481v2
+2015-11-12,"Strong trajectory and global $\mathbf{W^{1,p}}$-attractors for the damped-driven Euler system in $\mathbb R^2$","We consider the damped and driven two-dimensional Euler equations in the
+plane with weak solutions having finite energy and enstrophy. We show that
+these (possibly non-unique) solutions satisfy the energy and enstrophy
+equality. It is shown that this system has a strong global and a strong
+trajectory attractor in the Sobolev space $H^1$. A similar result on the strong
+attraction holds in the spaces $H^1\cap\{u:\ \|\mathrm{curl}
+u\|_{L^p}<\infty\}$ for $p\ge2$.",1511.03873v1
+2015-11-14,Infinite energy solutions for critical wave equation with fractional damping in unbounded domains,"This work is devoted to infinite-energy solutions of semi-linear wave
+equations in unbounded smooth domains of $\mathbb{R}^3$ with fractional damping
+of the form $(-\Delta_x+1)^\frac{1}{2}\partial_t u$. The work extends
+previously known results for bounded domains in finite energy case.
+Furthermore, well-posedness and existence of locally-compact smooth attractors
+for the critical quintic non-linearity are obtained under less restrictive
+assumptions on non-linearity, relaxing some artificial technical conditions
+used before. This is achieved by virtue of new type Lyapunov functional that
+allows to establish extra space-time regularity of solutions of Strichartz
+type.",1511.04592v1
+2015-11-14,Parametric resonance induced chaos in magnetic damped driven pendulum,"A damped driven pendulum with a magnetic driving force, appearing from a
+solenoid, where ac current flows is considered. The solenoid acts on the
+magnet, which is located at the free end of the pendulum. In this system, the
+existence and interrelation of chaos and parametric resonance is theoretically
+examined. Derived analytical results are supported by numerical simulations and
+conducted experiments.",1511.04593v2
+2015-11-19,Periodic damping gives polynomial energy decay,"Let $u$ solve the damped Klein--Gordon equation $$ \big( \partial_t^2-\sum
+\partial_{x_j}^2 +m \text{Id} +\gamma(x) \partial_t \big) u=0 $$ on
+$\mathbb{R}^n$ with $m>0$ and $\gamma\geq 0$ bounded below on a $2 \pi
+\mathbb{Z}^n$-invariant open set by a positive constant. We show that the
+energy of the solution $u$ decays at a polynomial rate. This is proved via a
+periodic observability estimate on $\mathbb{R}^n.$",1511.06144v5
+2015-12-03,Evidence for the role of normal-state electrons in nanoelectromechanical damping mechanisms at very low temperatures,"We report on experiments performed at low temperatures on aluminum covered
+silicon nanoelectromechanical resonators. The substantial difference observed
+between the mechanical dissipation in the normal and superconducting states
+measured within the same device unambiguously demonstrates the importance of
+normal-state electrons in the damping mechanism. The dissipative component
+becomes vanishingly small at very low temperatures in the superconducting
+state, leading to exceptional values for the quality factor of such small
+silicon structures. A critical discussion is given within the framework of the
+standard tunneling model.",1512.01036v1
+2015-12-31,Nonlinear stochastic evolution equations of second order with damping,"Convergence of a full discretization of a second order stochastic evolution
+equation with nonlinear damping is shown and thus existence of a solution is
+established. The discretization scheme combines an implicit time stepping
+scheme with an internal approximation. Uniqueness is proved as well.",1512.09260v2
+2016-01-18,Stabilizing the Long-time Behavior of the Navier-Stokes Equations and Damped Euler Systems by Fast Oscillating Forces,"The paper studies the issue of stability of solutions to the Navier-Stokes
+and damped Euler systems in periodic boxes. We show that under action of fast
+oscillating-in- time external forces all two dimensional regular solutions
+converge to a time periodic flow. Unexpectedly, effects of stabilization can be
+also obtained for systems with stationary forces with large total momentum
+(average of the velocity). Thanks to the Galilean transformation and space
+boundary conditions, the stationary force changes into one with time
+oscillations. In the three dimensional case we show an analogical result for
+weak solutions to the Navier- Stokes equations.",1601.04612v1
+2016-01-27,Design of a large dynamic range readout unit for the PSD detector of DAMPE,"A large dynamic range is required by the Plastic Scintillator Detector (PSD)
+of DArk Matter Paricle Explorer (DAMPE), and a double-dynode readout has been
+developed. To verify this design, a prototype detector module has been
+constructed and tested with cosmic rays and heavy ion beams. The results match
+with the estimation and the readout unit could easily cover the required
+dynamic range.",1601.07234v1
+2016-02-09,Engineering and Suppression of Decoherence in Two Qubit Systems,"In this work, two experimentally feasible methods of decoherence
+engineering-one based on the application of stochastic classical kicks and the
+other based on temporally randomized pulse sequences are combined. A different
+coupling interaction is proposed, which leads to amplitude damping as compared
+to existing methods which model phase damping, utilizing the $zz$ coupling
+interaction. The decoherence process on combining the stochastic kick method
+and the randomized pulse sequence method and the effectiveness of dynamical
+decoupling under these coupling interactions are analyzed. Finally, a
+counter-intuitive result where decoherence is suppressed in the presence of two
+noise sources under certain resonant conditions is presented.",1602.03026v1
+2016-02-10,Attractors for the strongly damped wave equation with $p$-Laplacian,"This paper is concerned with the initial boundary value problem for one
+dimensional strongly damped wave equation involving $p$-Laplacian. For $p>2$,
+we establish the existence of weak local attractors for this problem in
+$W_{0}^{1,p}(0,1)\times L^{2}(0,1)$. Under restriction $2<p<4$, we prove that
+the semigroup, generated by the considered problem, possesses a strong global
+attractor in $W_{0}^{1,p}(0,1)\times L^{2}(0,1)$ and this attractor is a
+bounded subset of $W^{1,\infty }(0,1)\times W^{1,\infty }(0,1)$.",1602.03339v3
+2016-02-11,Renormalization Group Study of a Fragile Fermi liquid in $1+ε$ dimensions,"We present a calculation of the low energy Greens function in $1+\epsilon$
+dimensions using the method of extended poor man's scaling, developed here. We
+compute the wave function renormalization $Z(\omega)$ and also the decay rate
+near the Fermi energy. Despite the lack of $\omega^2$ damping characteristic of
+3-dimensional Fermi liquids, we show that quasiparticles do exist in
+$1+\epsilon$ dimensions, in the sense that the quasiparticle weight $Z$ is
+finite and that the damping rate is smaller than the energy. We explicitly
+compute the crossover from this behavior to a 1-dimensional type
+Tomonaga-Luttinger liquid behavior at higher energies.",1602.03613v2
+2016-02-20,Movement of time-delayed hot spots in Euclidean space,"We investigate the shape of the solution of the Cauchy problem for the damped
+wave equation. In particular, we study the existence, location and number of
+spatial maximizers of the solution. Studying the shape of the solution of the
+damped wave equation, we prepare a decomposed form of the solution into the
+heat part and the wave part. Moreover, as its another application, we give
+$L^p$-$L^q$ estimates of the solution.",1602.06376v1
+2016-03-04,Optical realization of the dissipative quantum oscillator,"An optical realization of the damped quantum oscillator, based on transverse
+light dynamics in an optical resonator with slowly-moving mirrors, is
+theoretically suggested. The optical resonator setting provides a simple
+implementation of the time-dependent Caldirola-Kanai Hamiltonian of the
+dissipative quantum oscillator, and enables to visualize the effects of damped
+oscillations in the classical (ray optics) limit and wave packet collapse in
+the quantum (wave optics) regime.",1603.01364v1
+2016-03-08,Modifications of the Lifshitz-Kosevich formula in two-dimensional Dirac systems,"Starting from the Luttinger-Ward functional we derive an expression for the
+oscillatory part of the grand potential of a two dimensional Dirac system in a
+magnetic field. We perform the computation for the clean and the disordered
+system, and we study the effect of electron-electron interactions on the
+oscillations. Unlike in the two dimensional electron gas (2DEG), a finite
+temperature and impurity scattering also affects the oscillation frequency.
+Furthermore, we find that in graphene, compared to the 2DEG, additional
+interaction induced damping effects occur: to two-loop order electron-electron
+interactions do lead to an additional damping factor in the amplitude of the
+Lifshitz-Kosevich-formula.",1603.02559v1
+2016-03-23,Landau damping for the linearized Vlasov Poisson equation in a weakly collisional regime,"In this paper, we consider the linearized Vlasov-Poisson equation around an
+homogeneous Maxwellian equilibrium in a weakly collisional regime: there is a
+parameter $\eps$ in front of the collision operator which will tend to $0$.
+Moreover, we study two cases of collision operators, linear Boltzmann and
+Fokker-Planck. We prove a result of Landau damping for those equations in
+Sobolev spaces uniformly with respect to the collision parameter $\eps$ as it
+goes to $0$.",1603.07219v2
+2016-04-14,Higher order asymptotic expansions to the solutions for a nonlinear damped wave equation,"We study the Cauchy problem for a nonlinear damped wave equation. Under
+suitable assumptions for the nonlinearity and the initial data, we obtain the
+global solution which satisfies weighted $L^1$ and $L^\infty$ estimates.
+Furthermore, we establish the higher order asymptotic expansion of the
+solution. This means that we construct the nonlinear approximation of the
+global solution with respect to the weight of the data. Our proof is based on
+the approximation formula of the linear solution, which is given in [36], and
+the nonlinear approximation theory for a nonlinear parabolic equation developed
+by [18].",1604.04100v1
+2016-04-18,On the pressureless damped Euler-Poisson equations with non-local forces: Critical thresholds and large-time behavior,"We analyse the one-dimensional pressureless Euler-Poisson equations with a
+linear damping and non-local interaction forces. These equations are relevant
+for modelling collective behavior in mathematical biology. We provide a sharp
+threshold between the supercritical region with finite-time breakdown and the
+subcritical region with global-in-time existence of the classical solution. We
+derive an explicit form of solution in Lagrangian coordinates which enables us
+to study the time-asymptotic behavior of classical solutions with the initial
+data in the subcritical region.",1604.05229v1
+2016-05-24,Non-existence for fractionally damped fractional differential problems,"In this paper, we are concerned with a fractional differential inequality
+containing a lower order fractional derivative and a polynomial source term in
+the right hand side. A non-existence of non-trivial global solutions result is
+proved in an appropriate space by means of the test-function method. The range
+of blow up is found to depend only on the lower order derivative. This is in
+line with the well-known fact for an internally weakly damped wave equation
+that solutions will converge to solutions of the parabolic part.",1605.07432v1
+2016-05-31,On the Benjamin-Bona-Mahony equation with a localized damping,"We introduce several mechanisms to dissipate the energy in the
+Benjamin-Bona-Mahony (BBM) equation. We consider either a distributed
+(localized) feedback law, or a boundary feedback law. In each case, we prove
+the global wellposedness of the system and the convergence towards a solution
+of the BBM equation which is null on a band. If the Unique Continuation
+Property holds for the BBM equation, this implies that the origin is
+asymp-totically stable for the damped BBM equation.",1605.09574v1
+2016-06-03,Microscopic derivation of the one qubit Kraus operators for amplitude and phase damping,"This article presents microscopic derivation of the Kraus operators for (the
+generalized) amplitude and phase damping process. Derivation is based on the
+recently developed method [Andersson et al, J. Mod.Opt. 54, 1695 (2007)] which
+concerns finite dimensional systems (e.g. qubit). The form of these operators
+is usually estimated without insight into the microscopic details of the
+dynamics. The behavior of the qubit dynamics is simulated and depicted via
+Bloch sphere change.",1606.01145v1
+2016-06-08,Energy Decay in a Wave Guide with Dissipation at Infinity,"We prove local and global energy decay for the wave equation in a wave guide
+with damping at infinity. More precisely, the absorption index is assumed to
+converge slowly to a positive constant, and we obtain the diffusive phenomenon
+typical for the contribution of low frequencies when the damping is effective
+at infinity. On the other hand, the usual Geometric Control Condition is not
+necessarily satisfied so we may have a loss of regularity for the contribution
+of high frequencies. Since our results are new even in the Euclidean space, we
+also state a similar result in this case.",1606.02549v2
+2016-06-29,Damped Topological Magnons in the Kagomé-Lattice Ferromagnets,"We demonstrate that interactions can substantially undermine the
+free-particle description of magnons in ferromagnets on geometrically
+frustrated lattices. The anharmonic coupling, facilitated by the
+Dzyaloshinskii-Moriya interaction, and a highly-degenerate two-magnon continuum
+yield a strong, non-perturbative damping of the high-energy magnon modes. We
+provide a detailed account of the effect for the $S=1/2$ ferromagnet on the
+kagom\'e lattice and propose further experiments.",1606.09249v3
+2016-07-06,Asymptotic profiles of solutions for structural damped wave equations,"In this paper, we obtain several asymptotic profiles of solutions to the
+Cauchy problem for structurally damped wave equations $\partial_{t}^{2} u -
+\Delta u + \nu (-\Delta)^{\sigma} \partial_{t} u=0$, where $\nu >0$ and $0<
+\sigma \le1$. Our result is the approximation formula of the solution by a
+constant multiple of a special function as $t \to \infty$, which states that
+the asymptotic profiles of the solutions are classified into $5$ patterns
+depending on the values $\nu$ and $\sigma$.",1607.01839v1
+2016-08-01,Landau-Khalatnikov phonon damping in strongly interacting Fermi gases,"We derive the phonon damping rate due to the four-phonon Landau-Khalatnikov
+process in low temperature strongly interacting Fermi gases using quantum
+hydrodynamics, correcting and extending the original calculation of Landau and
+Khalatnikov [ZhETF, 19 (1949) 637]. Our predictions can be tested in
+state-of-the-art experiments with cold atomic gases in the collisionless
+regime.",1608.00402v3
+2016-08-17,New mechanism of acceleration of particles by stellar black holes,"In this paper we study efficiency of particle acceleration in the
+magnetospheres of stellar mass black holes. For this purpose we consider the
+linearized set of the Euler equation, continuity equation and Poisson equation
+respectively. After introducing the varying relativistic centrifugal force, we
+show that the charge separation undergoes the parametric instability, leading
+to generation of centrifugally excited Langmuir waves. It is shown that these
+waves, via the Langmuir collapse damp by means of the Landau damping, as a
+result energy transfers to particles accelerating them to energies of the order
+of $10^{16}$eV.",1608.04889v1
+2016-10-09,Beam halo study on ATF damping ring,"Halo distribution is a key topic for background study. This paper has
+developed an analytical method to give an estimation of ATF beam halo
+distribution. The equilibrium particle distribution of the beam tail in the ATF
+damping ring is calculated analytically with different emittance and different
+vacuum degree. The analytical results agree the measurements very well. This is
+a general method which can be applied to any electron rings.",1610.02624v1
+2016-10-11,"Damping of hard excitations in strongly coupled $\mathcal N\,{=}\,4$ plasma","The damping of high momentum excitations in strongly coupled maximally
+supersymmetric Yang-Mills plasma is studied. Previous calculations of the
+asymptotic behavior of the quasinormal mode spectrum are extended and
+clarified. We confirm that subleading corrections to the lightlike dispersion
+relation $\omega({\bf q}) = |{\bf q}|$ have a universal $|{\bf q}|^{-1/3}$
+form. Sufficiently narrow, weak planar shocks may be viewed as coherent
+superpositions of short wavelength quasinormal modes. The attenuation and
+evolution in profile of narrow planar shocks are examined as an application of
+our results.",1610.03491v1
+2016-10-24,Assessing the quantumness of a damped two-level system,"We perform a detailed analysis of the nonclassical properties of a damped
+two-level system. We compute and compare three different criteria of
+quantumness, the $l_1$-norm of coherence, the Leggett- Garg inequality and a
+quantum witness based on the no-signaling in time condition. We show that all
+three quantum indicators decay exponentially in time as a result of the
+coupling to the thermal reservoir. We further demonstrate that the
+corresponding characteristic times are identical and given by the coherence
+half-life. These results quantify how violations of Leggett-Garg inequalities
+and nonzero values of the quantum witness are connected to the coherence of the
+two-level system.",1610.07626v1
+2016-10-26,Restoring genuine tripartite entanglement under local amplitude damping,"We investigate the possibility to restore genuine tripartite entanglement
+under local amplitude damping. We show that it is possible to protect genuine
+entanglement using CNOT and Hadamard gates. We analyze several ordering of such
+recovery operations. We find that for recovery operations applied after
+exposing qubits to decoherence, there is no enhancement in lifetime of genuine
+entanglement. Actual retrieval of entanglement is only possible when reversal
+scheme is applied before and after the decoherence process. We find that
+retrieval of entanglement for mixture of $|\widetilde{W}\rangle$ state with
+white noise is more evident than the respective mixture of $|W\rangle$ state.
+We also find the retrieval of entanglement for similar mixture of $|GHZ\rangle$
+state as well.",1610.08280v1
+2016-10-27,Linear Inviscid Damping for Couette Flow in Stratified Fluid,"We study the inviscid damping of Couette flow with an exponentially
+stratified density. The optimal decay rates of the velocity field and the
+density are obtained for general perturbations with minimal regularity. For
+Boussinesq approximation model, the decay rates we get are consistent with the
+previous results in the literature. We also study the decay rates for the full
+Euler equations of stratified fluids, which were not studied before. For both
+models, the decay rates depend on the Richardson number in a very similar way.
+Besides, we also study the dispersive decay due to the exponential
+stratification when there is no shear.",1610.08924v2
+2016-11-01,On the penalty stabilization mechanism for upwind discontinuous Galerkin formulations of first order hyperbolic systems,"Penalty fluxes are dissipative numerical fluxes for high order discontinuous
+Galerkin (DG) methods which depend on a penalization parameter. We investigate
+the dependence of the spectra of high order DG discretizations on this
+parameter, and show that as its value increases, the spectra of the DG
+discretization splits into two disjoint sets of eigenvalues. One set converges
+to the eigenvalues of a conforming discretization, while the other set
+corresponds to spurious eigenvalues which are damped proportionally to the
+parameter. Numerical experiments also demonstrate that undamped spurious modes
+present in both in the limit of zero and large penalization parameters are
+damped for moderate values of the upwind parameter.",1611.00102v2
+2016-11-26,Landau damping of surface plasmons in metal nanostructures,"We develop a quantum-mechanical theory for Landau damping of surface plasmons
+in metal nanostructures larger that the characteristic length for nonlocal
+effects. We show that the electron surface scattering, which facilitates
+plasmon decay in small nanostructures, can be incorporated into the metal
+dielectric function on par with phonon and impurity scattering. The derived
+surface scattering rate is determined by the plasmon local field polarization
+relative to the metal-dielectric interface and is highly sensitive to the
+system geometry. We illustrate our model by providing analytical results for
+surface scattering rate in some common shape nanostructures.",1611.08670v3
+2016-11-27,Convergence in probability of an ergodic and conformal multi-symplectic numerical scheme for a damped stochastic NLS equation,"In this paper, we investigate the convergence order in probability of a novel
+ergodic numerical scheme for damped stochastic nonlinear Schr\""{o}dinger
+equation with an additive noise. Theoretical analysis shows that our scheme is
+of order one in probability under appropriate assumptions for the initial value
+and noise. Meanwhile, we show that our scheme possesses the unique ergodicity
+and preserves the discrete conformal multi-symplectic conservation law.
+Numerical experiments are given to show the longtime behavior of the discrete
+charge and the time average of the numerical solution, and to test the
+convergence order, which verify our theoretical results.",1611.08778v1
+2016-12-27,Wiggler for CESR operation at 2 GeV,"For low energy operation strategy we advocate utilization of many short
+wigglers in contrast with single long wiggler. This allows begin to operate
+very naturally with few strong field wigglers giving necessary damping time on
+expense of energy spread. By adding more and more wigglers in the ring, as
+these wigglers are manufactured and tuned, the field in the wigglers will be
+decreased, keeping necessary damping. This strategy allows the mostly effective
+operation of CESR with minimum down time. This also gives flexibility in
+operation in wider energy scale without non-reversible modifications.",1612.09227v1
+2017-01-30,Energy Transport Property of Charged Particles with Time-Dependent Damping Force via Manifold-Based Analysis Approach,"This paper deals with the energy transport properties of charged particles
+with time-dependent damping force. Based on the proposed nonlinear
+dimensionless mapping,the stability and dynamical evolution of the particle
+system is analyzed with the help of manifold-based analysis approach.It has
+been found that the particle system possesses two types of energy asymptotic
+behaviors. More significantly, the underlying mechanism of an ""energy barrier""
+is uncovered,i.e., one generalized invariant spanning curve emerges in the
+dissipative particle system. These results will be useful to enrich the energy
+transport behavior knowledge of the particle system.",1701.08762v1
+2017-02-22,Integration by parts of some non-adapted vector field from Malliavin's lifting approach,"In this paper we propose a lift of vector field $X$ on a Riemannian manifold
+$M$ to a vector field $\tilde{X}$ on the curved Cameron-Martin space
+$H\left(M\right)$ named orthogonal lift. The construction of this lift is based
+on a least square spirit with respect to a metric on $H(M)$ reflecting the
+damping effect of Ricci curvature. Its stochastic extension gives rise to a
+non-adapted Cameron-Martin vector field on $W_o(M)$. In particular, if
+$M=\mathbb{R}^d$ with Euclidean metric, then the damp disappears and the lift
+reduces to the well-known Malliavin's lift. We establish an integration by
+parts formula for these first order differential operators.",1702.06741v1
+2017-02-23,The sharp lifespan estimate for semilinear damped wave equation with Fujita critical power in high dimensions,"This paper is concerned about the lifespan estimate to the Cauchy problem of
+semilinear damped wave equations with the Fujita critical exponent in high
+dimensions$(n\geq 4)$. We establish the sharp upper bound of the lifespan in
+the following form \begin{equation}\nonumber\\ \begin{aligned}
+T(\varepsilon)\leq \exp(C\varepsilon^{-\frac 2n}), \end{aligned} \end{equation}
+by using the heat kernel as the test function.",1702.07073v2
+2017-03-09,Off resonance coupling between a cavity mode and an ensemble of driven spins,"We study the interaction between a superconducting cavity and a spin
+ensemble. The response of a cavity mode is monitored while simultaneously the
+spins are driven at a frequency close to their Larmor frequency, which is tuned
+to a value much higher than the cavity resonance. We experimentally find that
+the effective damping rate of the cavity mode is shifted by the driven spins.
+The measured shift in the damping rate is attributed to the retarded response
+of the cavity mode to the driven spins. The experimental results are compared
+with theoretical predictions and fair agreement is found.",1703.03311v1
+2017-03-10,Negative Landau damping in bilayer graphene,"We theoretically demonstrate that a system formed by two coupled graphene
+sheets enables a negative damping regime wherein graphene plasmons are pumped
+by a DC current. This effect is triggered by electrons drifting through one of
+the graphene sheets and leads to the spontaneous light emission (spasing) and
+wave instabilities in the mid-infrared range. It is shown that there is a deep
+link between the drift-induced instabilities and wave instabilities in moving
+media, as both result from the hybridization of oscillators with oppositely
+signed frequencies. With a thickness of few nanometers and wide spectral
+tunability, the proposed structure may find interesting applications in
+nanophotonic circuitry as an on-chip light source.",1703.03623v1
+2017-03-10,Effects on the CMB from magnetic field dissipation before recombination,"Magnetic fields present before decoupling are damped due to radiative
+viscosity. This energy injection affects the thermal and ionization history of
+the cosmic plasma. The implications for the CMB anisotropies and polarization
+are investigated for different parameter choices of a non helical stochastic
+magnetic field. Assuming a Gaussian smoothing scale determined by the magnetic
+damping wave number at recombination it is found that magnetic fields with
+present day strength less than 0.1 nG and negative magnetic spectral indices
+have a sizeable effect on the CMB temperature anisotropies and polarization.",1703.03650v1
+2017-03-28,(1+1) Newton-Hooke Group for the Simple and Damped Harmonic Oscillator,"It is demonstrated that, in the framework of the orbit method, a simple and
+damped harmonic oscillators are indistinguishable at the level of an abstract
+Lie algebra. This opens a possibility for treating the dissipative systems
+within the orbit method. In depth analysis of the coadjoint orbits of the
+$(1+1)$ dimensional Newton-Hooke group are presented. Further, it is argued
+that the physical interpretation is carried by a specific realisation of the
+Lie algebra of smooth functions on a phase space rather than by an abstract Lie
+algebra.",1703.09583v2
+2017-04-09,Controllability of the Strongly Damped Impulsive Semilinear Wave Equation with Memory and Delay,"This article is devoted to study the interior approximated controllability of
+the strongly damped semilinear wave equation with memory, impulses and delay
+terms. The problem is challenging since the state equation contains memory and
+impulsive terms yielding to potential unbounded control sequences steering the
+system to a neighborhood of the final state, thus fixed point theorems cannot
+be used directly. As alternative, the A.E Bashirov and et al. techniques are
+applied and together with the delay allow the control solution to be directed
+to fixed curve in a short time interval and achieve our result.",1704.02561v1
+2017-04-12,Damping parametric instabilities in future gravitational wave detectors by means of electrostatic actuators,"It has been suggested that the next generation of interferometric
+gravitational wave detectors may observe spontaneously excited parametric
+oscillatory instabilities. We present a method of actively suppressing any such
+instability through application of electrostatic forces to the interferometers'
+test masses. Using numerical methods we quantify the actuation force required
+to damp candidate instabilities and find that such forces are readily
+achievable. Our predictions are subsequently verified experimentally using
+prototype Advanced LIGO hardware, conclusively demonstrating the effectiveness
+of our approach.",1704.03587v1
+2017-04-28,Cross-damping effects in 1S-3S spectroscopy of hydrogen and deuterium,"We calculate the cross-damping frequency shift of a laser-induced two-photon
+transition monitored through decay fluorescence, by adapting the analogy with
+Raman scattering developed by Amaro et al. [P. Amaro et al., PRA 92, 022514
+(2015)]. We apply this method to estimate the frequency shift of the 1S-3S
+transition in hydrogen and deuterium. Taking into account our experimental
+conditions, we find a frequency shift of less than 1 kHz, that is smaller than
+our current statistical uncertainty.",1704.09003v1
+2017-05-15,Damping self-forces and Asymptotic Symmetries,"Energy conservation in radiating processes requires, at the classical level,
+to take into account damping forces on the sources. These forces can be
+represented in terms of asymptotic data and lead to charges defined as
+integrals over the asymptotic boundary. For scattering processes these charges,
+in case of zero radiated energy, are conserved and encode the information about
+the sub-leading soft theorems and matching conditions. The QED version of the
+self forces is associated with the dependence of the differential cross section
+on the infrared resolution scale.",1705.05297v2
+2017-05-17,Exact Model Reduction for Damped-Forced Nonlinear Beams: An Infinite-Dimensional Analysis,"We use invariant manifold results on Banach spaces to conclude the existence
+of spectral submanifolds (SSMs) in a class of nonlinear, externally forced beam
+oscillations. SSMs are the smoothest nonlinear extensions of spectral subspaces
+of the linearized beam equation. Reduction of the governing PDE to SSMs
+provides an explicit low-dimensional model which captures the correct
+asymptotics of the full, infinite-dimensional dynamics. Our approach is general
+enough to admit extensions to other types of continuum vibrations. The
+model-reduction procedure we employ also gives guidelines for a mathematically
+self-consistent modeling of damping in PDEs describing structural vibrations.",1705.06133v1
+2017-06-26,Weighted energy estimates for wave equation with space-dependent damping term for slowly decaying initial data,"This paper is concerned with weighted energy estimates for solutions to wave
+equation $\partial_t^2u-\Delta u + a(x)\partial_tu=0$ with space-dependent
+damping term $a(x)=|x|^{-\alpha}$ $(\alpha\in [0,1))$ in an exterior domain
+$\Omega$ having a smooth boundary. The main result asserts that the weighted
+energy estimates with weight function like polymonials are given and these
+decay rate are almost sharp, even when the initial data do not have compact
+support in $\Omega$. The crucial idea is to use special solution of $\partial_t
+u=|x|^{\alpha}\Delta u$ including Kummer's confluent hypergeometric functions.",1706.08311v1
+2017-08-09,Global well-posedness for the 2D Boussinesq equations with a velocity damping term,"In this paper, we prove global well-posedness of smooth solutions to the
+two-dimensional incompressible Boussinesq equations with only a velocity
+damping term when the initial data is close to an nontrivial equilibrium state
+$(0,x_2)$. As a by-product, under this equilibrium state, our result gives a
+positive answer to the question proposed by [ACWX] (see P.3597).",1708.02695v4
+2017-08-18,Second sound in systems of one-dimensional fermions,"We study sound in Galilean invariant systems of one-dimensional fermions. At
+low temperatures, we find a broad range of frequencies in which in addition to
+the waves of density there is a second sound corresponding to ballistic
+propagation of heat in the system. The damping of the second sound mode is
+weak, provided the frequency is large compared to a relaxation rate that is
+exponentially small at low temperatures. At lower frequencies the second sound
+mode is damped, and the propagation of heat is diffusive.",1708.05733v2
+2017-08-21,Equilibrium of a Brownian particle with coordinate dependent diffusivity and damping: Generalized Boltzmann distribution,"Fick's law for coordinate dependent diffusivity is derived. Corresponding
+diffusion current in the presence of coordinate dependent diffusivity is
+consistent with the form as given by Kramers-Moyal expansion. We have obtained
+the equilibrium solution of the corresponding Smoluchowski equation. The
+equilibrium distribution is a generalization of the Boltzmann distribution.
+This generalized Boltzmann distribution involves an effective potential which
+is a function of coordinate dependent diffusivity. We discuss various
+implications of the existence of this generalized Boltzmann distribution for
+equilibrium of systems with coordinate dependent diffusivity and damping.",1708.06132v5
+2017-08-21,Global small solutions of 3D incompressible Oldroyd-B model without damping mechanism,"In this paper, we prove the global existence of small smooth solutions to the
+three-dimensional incompressible Oldroyd-B model without damping on the stress
+tensor. The main difficulty is the lack of full dissipation in stress tensor.
+To overcome it, we construct some time-weighted energies based on the special
+coupled structure of system. Such type energies show the partial dissipation of
+stress tensor and the strongly full dissipation of velocity. In the view of
+treating ""nonlinear term"" as a ""linear term"", we also apply this result to 3D
+incompressible viscoelastic system with Hookean elasticity and then prove the
+global existence of small solutions without the physical assumption (div-curl
+structure) as previous works.",1708.06172v2
+2017-10-13,$L^2$ asymptotic profiles of solutions to linear damped wave equations,"In this paper we obtain higher order asymptotic profilles of solutions to the
+Cauchy problem of the linear damped wave equation in $\textbf{R}^n$
+\begin{equation*} u_{tt}-\Delta u+u_t=0, \qquad u(0,x)=u_0(x), \quad
+u_t(0,x)=u_1(x), \end{equation*} where $n\in\textbf{N}$ and $u_0$, $u_1\in
+L^2(\textbf{R}^n)$. Established hyperbolic part of asymptotic expansion seems
+to be new in the sense that the order of the expansion of the hyperbolic part
+depends on the spatial dimension.",1710.04870v1
+2017-11-27,Statistical mechanics of Landau damping,"Landau damping is the tendency of solutions to the Vlasov equation towards
+spatially homogeneous distribution functions. The distribution functions
+however approach the spatially homogeneous manifold only weakly, and Boltzmann
+entropy is not changed by Vlasov equation. On the other hand, density and
+kinetic energy density, which are integrals of the distribution function,
+approach spatially homogeneous states strongly, which is accompanied by growth
+of the hydrodynamic entropy. Such a behavior can be seen when Vlasov equation
+is reduced to the evolution equations for density and kinetic energy density by
+means of the Ehrenfest reduction.",1711.10022v1
+2017-11-29,Lepton-portal Dark Matter in Hidden Valley model and the DAMPE recent results,"We study the recent $e^\pm$ cosmic ray excess reported by DAMPE in a Hidden
+Valley Model with lepton-portal dark matter. We find the electron-portal can
+account for the excess well and satisfy the DM relic density and direct
+detection bounds, while electron+muon/electron+muon+tau-portal suffers from
+strong constraints from lepton flavor violating observables, such as $\mu \to 3
+e$. We also discuss possible collider signatures of our model, both at the LHC
+and a future 100 TeV hadron collider.",1711.11058v3
+2017-11-30,"Radiative Dirac neutrino mass, DAMPE dark matter and leptogenesis","We explain the electron-positron excess reported by the DAMPE collaboration
+recently in a radiative Dirac seesaw model where a dark $U(1)_X$ gauge symmetry
+can (i) forbid the tree-level Yukawa couplings of three right-handed neutrinos
+to the standard model lepton and Higgs doublets, (ii) predict the existence of
+three dark fermions for the gauge anomaly cancellation, (iii) mediate a
+testable scattering of the lightest dark fermion off the nucleons. Our model
+can also accommodate a successful leptogenesis to generate the cosmic baryon
+asymmetry.",1711.11333v2
+2017-12-13,Sub-logistic source can prevent blow-up in the 2D minimal Keller-Segel chemotaxis system,"It is well-known that the Neumann initial-boundary value problem for the
+minimal-chemotaxis-logistic system in a 2D bounded smooth domain has no blow-up
+for any choice of parameters. Here, for a large class of kinetic terms
+including sub-logistic sources, we show that the corresponding 2D Neumann
+initial-boundary value problems do not possess any blow-up. This illustrates a
+new phenomenon that even a class of sub-logistic sources can prevent blow-up
+for the 2D problem, indicating that logistic damping is not the weakest damping
+to guarantee uniform-in-time boundedness for the 2D minimal Keller-Segel
+chemotaxis model.",1712.04739v1
+2017-12-16,Convergence to Equilibrium in Wasserstein distance for damped Euler equations with interaction forces,"We develop tools to construct Lyapunov functionals on the space of
+probability measures in order to investigate the convergence to global
+equilibrium of a damped Euler system under the influence of external and
+interaction potential forces with respect to the 2-Wasserstein distance. We
+also discuss the overdamped limit to a nonlocal equation used in the modelling
+of granular media with respect to the 2-Wasserstein distance, and provide
+rigorous proofs for particular examples in one spatial dimension.",1712.05923v2
+2017-12-27,Normal-mode-based analysis of electron plasma waves with second-order Hermitian formalism,"The classic problem of the dynamic evolution of Langmuir electron waves in a
+collisionless plasma and their Landau damping is cast as a second-order,
+self-adjoint problem with a continuum spectrum of real and positive squared
+frequencies. The corresponding complete basis of singular normal modes is
+obtained, along with their orthogonality relation. This yields easily the
+general expression of the time-reversal-invariant solution for any
+initial-value problem. An example is given for a specific initial condition
+that illustrates the Landau damping of the macroscopic moments of the
+perturbation.",1712.09682v1
+2018-01-19,Discontinuous energy shaping control of the Chaplygin sleigh,"In this paper we present an energy shaping control law for set-point
+regulation of the Chaplygin sleigh. It is well known that nonholonomic
+mechanical systems cannot be asymptotically stabilised using smooth control
+laws as they do no satisfy Brockett's necessary condition for smooth
+stabilisation. Here, we propose a discontinuous control law that can be seen as
+a potential energy shaping and damping injection controller. The proposed
+controller is shown to be robust against the parameters of both the inertia
+matrix and the damping structure of the open-loop system.",1801.06278v1
+2018-01-19,Robust integral action of port-Hamiltonian systems,"Interconnection and damping assignment, passivity-based control (IDA-PBC) has
+proven to be a successful control technique for the stabilisation of many
+nonlinear systems. In this paper, we propose a method to robustify a system
+which has been stabilised using IDA-PBC with respect to constant, matched
+disturbances via the addition of integral action. The proposed controller
+extends previous work on the topic by being robust against the damping of the
+system, a quantity which may not be known in many applications.",1801.06279v1
+2018-01-19,A study of Landau damping with random initial inputs,"For the Vlasov-Poisson equation with random uncertain initial data, we prove
+that the Landau damping solution given by the deterministic counterpart
+(Caglioti and Maffei, {\it J. Stat. Phys.}, 92:301-323, 1998) depends smoothly
+on the random variable if the time asymptotic profile does, under the
+smoothness and smallness assumptions similar to the deterministic case. The
+main idea is to generalize the deterministic contraction argument to more
+complicated function spaces to estimate derivatives in space, velocity and
+random variables. This result suggests that the random space regularity can
+persist in long-time even in time-reversible nonlinear kinetic equations.",1801.06304v1
+2018-01-31,Smoluchowski-Kramers approximation for the damped stochastic wave equation with multiplicative noise in any spatial dimension,"We show that the solutions to the damped stochastic wave equation converge
+pathwise to the solution of a stochastic heat equation. This is called the
+Smoluchowski-Kramers approximation. Cerrai and Freidlin have previously
+demonstrated that this result holds in the cases where the system is exposed to
+additive noise in any spatial dimension or when the system is exposed to
+multiplicative noise and the spatial dimension is one. The current paper proves
+that the Smoluchowski-Kramers approximation is valid in any spatial dimension
+when the system is exposed to multiplicative noise.",1801.10538v1
+2018-02-28,Global-in-time Stability of 2D MHD boundary Layer in the Prandtl-Hartmann Regime,"In this paper, we prove global existence of solutions with analytic
+regularity to the 2D MHD boundary layer equations in the mixed Prandtl and
+Hartmann regime derived by formal multi-scale expansion in \cite{GP}. The
+analysis shows that the combined effect of the magnetic diffusivity and
+transveral magnetic field on the boundary leads to a linear damping on the
+tangential velocity field near the boundary. And this damping effect yields the
+global in time analytic norm estimate in the tangential space variable on the
+perturbation of the classical steady Hartmann profile.",1802.10494v3
+2018-02-28,Modal approach to the controllability problem of distributed parameter systems with damping,"This paper is devoted to the controllability analysis of a class of linear
+control systems in a Hilbert space. It is proposed to use the minimum energy
+controls of a reduced lumped parameter system for solving the infinite
+dimensional steering problem approximately. Sufficient conditions of the
+approximate controllability are formulated for a modal representation of a
+flexible structure with small damping.",1803.00129v1
+2018-03-14,Study of Quantum Walk over a Square Lattice,"Quantum random walk finds application in efficient quantum algorithms as well
+as in quantum network theory. Here we study the mixing time of a discrete
+quantum walk over a square lattice in presence percolation and decoherence. We
+consider bit-flip and phase damping noise, and evaluate the instantaneous
+mixing time for both the cases. Using numerical analysis we show that in case
+of phase damping noise probability distribution of walker's position is
+sufficiently close to the uniform distribution after infinite time. However,
+during the action of bit-flip noise, even after infinite time the total
+variation distance between the two probability distributions is large enough.",1803.05152v1
+2018-04-10,Motion of a superconducting loop in an inhomogeneous magnetic field: a didactic experiment,"We present an experiment conductive to an understanding of both Faraday's law
+and the properties of the superconducting state. It consists in the analysis of
+the motion of a superconducting loop moving under the influence of gravity in
+an inhomogeneous horizontal magnetic field. Gravity, conservation of magnetic
+flux, and friction combine to give damped harmonic oscillations. The measured
+frequency of oscillation and the damping constant as a function of the magnetic
+field strength (the only free parameter) are in good agreement with the
+theoretical model.",1804.03553v1
+2018-05-08,Optomechanical damping as the origin of sideband asymmetry,"Sideband asymmetry in cavity optomechanics has been explained by particle
+creation and annihilation processes, which bestow an amplitude proportional to
+'n+1' and 'n' excitations to each of the respective sidebands. We discuss the
+issues with this as well as other interpretations, such as quantum backaction
+and noise interference, and show that the asymmetry is due to the
+optomechanical damping caused by the probe and the cooling lasers instead.",1805.02952v4
+2018-05-11,On the asymptotic stability of stratified solutions for the 2D Boussinesq equations with a velocity damping term,"We consider the 2D Boussinesq equations with a velocity damping term in a
+strip $\mathbb{T}\times[-1,1]$, with impermeable walls. In this physical
+scenario, where the \textit{Boussinesq approximation} is accurate when
+density/temperature variations are small, our main result is the asymptotic
+stability for a specific type of perturbations of a stratified solution. To
+prove this result, we use a suitably weighted energy space combined with linear
+decay, Duhamel's formula and ""bootstrap"" arguments.",1805.05179v2
+2018-06-30,A linearized and conservative Fourier pseudo-spectral method for the damped nonlinear Schrödinger equation in three dimensions,"In this paper, we propose a linearized Fourier pseudo-spectral method, which
+preserves the total mass and energy conservation laws, for the damped nonlinear
+Schr\""{o}dinger equation in three dimensions. With the aid of the semi-norm
+equivalence between the Fourier pseudo-spectral method and the finite
+difference method, an optimal $L^2$-error estimate for the proposed method
+without any restriction on the grid ratio is established by analyzing the real
+and imaginary parts of the error function. Numerical results are addressed to
+confirm our theoretical analysis.",1807.00091v3
+2018-07-11,Global existence and blow-up for semilinear damped wave equations in three space dimensions,"We consider initial value problem for semilinear damped wave equations in
+three space dimensions. We show the small data global existence for the problem
+without the spherically symmetric assumption and obtain the sharp lifespan of
+the solutions. This paper is devoted to a proof of the Takamura's conjecture on
+the lifespan of solutions.",1807.04327v3
+2018-07-18,B-field induced mixing between Langmuir waves and axions,"We present an analytic study of the dispersion relation for an isotropic
+magnetized plasma interacting with axions. We provide a quantitative picture of
+the electromagnetic plasma oscillations in both the ultrarelativistic and
+nonrelativistic regimes and considering both non-degenerate and degenerate
+media, accounting for the dispersion curves as a function of the plasma
+temperature and the ratio of the plasma phase velocity to the characteristic
+velocity of particles. We include the modifications on the Landau damping of
+plasma waves induced by the presence of the axion field, and we comment on the
+effects of damping on subluminal plasma oscillations.",1807.06828v2
+2018-07-26,Moment conditions and lower bounds in expanding solutions of wave equations with double damping terms,"In this report we obtain higher order asymptotic expansions of solutions to
+wave equations with frictional and viscoelastic damping terms. Although the
+diffusion phenomena are dominant, differences between the solutions we deal
+with and those of heat equations can be seen by comparing the second order
+expansions of them. In order to analyze such effects we consider the weighted
+L1 initial data. We also give some lower bounds which show the optimality of
+obtained expansions.",1807.10020v1
+2018-08-16,Continuity of the set equilibria of non-autonomous damped wave equations with terms concentrating on the boundary,"In this paper we are interested in the behavior of the solutions of
+non-autonomous damped wave equations when some reaction terms are concentrated
+in a neighborhood of the boundary and this neighborhood shrinks to boundary as
+a parameter \varepsilon goes to zero. We prove the conti- nuity of the set
+equilibria of these equations. Moreover, if an equilibrium solution of the
+limit problem is hyperbolic, then we show that the per- turbed equation has one
+and only one equilibrium solution nearby.",1808.05667v1
+2018-08-30,Protecting temporal correlations of two-qubit states using quantum channels with memory,"Quantum temporal correlations exhibited by violations of Leggett-Garg
+Inequality (LGI) and Temporal Steering Inequality (TSI) are in general found to
+be non-increasing under decoherence channels when probed on two-qubit pure
+entangled states. We study the action of decoherence channels, such as
+amplitude damping, phase-damping and depolarising channels when partial memory
+is introduced in a way such that two consecutive uses of the channels are
+time-correlated. We show that temporal correlations demonstrated by violations
+of the above temporal inequalities can be protected against decoherence using
+the effect of memory.",1808.10345v1
+2018-09-17,Global existence for weakly coupled systems of semi-linear structurally damped $σ$-evolution models with different power nonlinearities,"In this paper, we study the Cauchy problems for weakly coupled systems of
+semi-linear structurally damped $\sigma$-evolution models with different power
+nonlinearities. By assuming additional $L^m$ regularity on the initial data,
+with $m \in [1,2)$, we use $(L^m \cap L^2)- L^2$ and $L^2- L^2$ estimates for
+solutions to the corresponding linear Cauchy problems to prove the global (in
+time) existence of small data Sobolev solutions to the weakly coupled systems
+of semi-linear models from suitable function spaces.",1809.06744v2
+2018-10-15,Global well-posedness in the critical Besov spaces for the incompressible Oldroyd-B model without damping mechanism,"We prove the global well-posedness in the critical Besov spaces for the
+incompressible Oldroyd-B model without damping mechanism on the stress tensor
+in $\mathbb{R}^d$ for the small initial data. Our proof is based on the
+observation that the behaviors of Green's matrix to the system of
+$\big(u,(-\Delta)^{-\frac12}\mathbb{P}\nabla\cdot\tau\big)$ as well as the
+effects of $\tau$ change from the low frequencies to the high frequencies and
+the construction of the appropriate energies in different frequencies.",1810.06171v1
+2018-10-18,Global solutions to the $n$-dimensional incompressible Oldroyd-B model without damping mechanism,"The present work is dedicated to the global solutions to the incompressible
+Oldroyd-B model without damping on the stress tensor in $\mathbb{R}^n(n=2,3)$.
+This result allows to construct global solutions for a class of highly
+oscillating initial velocity. The proof uses the special structure of the
+system. Moreover, our theorem extends the previous result by Zhu [19] and
+covers the recent result by Chen and Hao [4].",1810.08048v3
+2018-10-30,Global well-posedness for nonlinear wave equations with supercritical source and damping terms,"We prove the global well-posedness of weak solutions for nonlinear wave
+equations with supercritical source and damping terms on a three-dimensional
+torus $\mathbb T^3$ of the prototype \begin{align*} &u_{tt}-\Delta
+u+|u_t|^{m-1}u_t=|u|^{p-1}u, \;\; (x,t) \in \mathbb T^3 \times \mathbb R^+ ;
+\notag\\ &u(0)=u_0 \in H^1(\mathbb T^3)\cap L^{m+1}(\mathbb T^3), \;\;
+u_t(0)=u_1\in L^2(\mathbb T^3), \end{align*} where $1\leq p\leq \min\{
+\frac{2}{3} m + \frac{5}{3} , m \}$. Notably, $p$ is allowed to be larger than
+$6$.",1810.12476v1
+2018-11-02,Nonlinear Damped Timoshenko Systems with Second Sound - Global Existence and Exponential Stability,"In this paper, we consider nonlinear thermoelastic systems of Timoshenko type
+in a one-dimensional bounded domain. The system has two dissipative mechanisms
+being present in the equation for transverse displacement and rotation angle -
+a frictional damping and a dissipation through hyperbolic heat conduction
+modelled by Cattaneo's law, respectively. The global existence of small, smooth
+solutions and the exponential stability in linear and nonlinear cases are
+established.",1811.01128v1
+2018-11-14,Quantum witness of a damped qubit with generalized measurements,"We evaluate the quantum witness based on the no-signaling-in-time condition
+of a damped two-level system for nonselective generalized measurements of
+varying strength. We explicitly compute its dependence on the measurement
+strength for a generic example. We find a vanishing derivative for weak
+measurements and an infinite derivative in the limit of projective
+measurements. The quantum witness is hence mostly insensitive to the strength
+of the measurement in the weak measurement regime and displays a singular,
+extremely sensitive dependence for strong measurements. We finally relate this
+behavior to that of the measurement disturbance defined in terms of the
+fidelity between pre-measurement and post-measurement states.",1811.06013v1
+2018-12-11,Blow up of solutions to semilinear non-autonomous wave equations under Robin boundary conditions,"The problem of blow up of solutions to the initial boundary value problem for
+non-autonomous semilinear wave equation with damping and accelerating terms
+under the Robin boundary condition is studied. Sufficient conditions of blow up
+in a finite time of solutions to semilinear damped wave equations with
+arbitrary large initial energy are obtained. A result on blow up of solutions
+with negative initial energy of semilinear second order wave equation with
+accelerating term is also obtained.",1812.04595v1
+2018-12-23,Global existence of weak solutions for strongly damped wave equations with nonlinear boundary conditions and balanced potentials,"We demonstrate the global existence of weak solutions to a class of
+semilinear strongly damped wave equations possessing nonlinear hyperbolic
+dynamic boundary conditions. Our work assumes $(-\Delta_W)^\theta \partial_tu$
+with $\theta\in[\frac{1}{2},1)$ and where $\Delta_W$ is the Wentzell-Laplacian.
+Hence, the associated linear operator admits a compact resolvent. A balance
+condition is assumed to hold between the nonlinearity defined on the interior
+of the domain and the nonlinearity on the boundary. This allows for arbitrary
+(supercritical) polynomial growth on each potential, as well as mixed
+dissipative/anti-dissipative behavior. Moreover, the nonlinear function defined
+on the interior of the domain is assumed to be only $C^0$.",1812.09781v1
+2018-12-24,Cold Damping of an Optically Levitated Nanoparticle to micro-Kelvin Temperatures,"We implement a cold damping scheme to cool one mode of the center-of-mass
+motion of an optically levitated nanoparticle in ultrahigh vacuum from room
+temperature to a record-low temperature of 100 micro-Kelvin. The measured
+temperature dependence on feedback gain and thermal decoherence rate is in
+excellent agreement with a parameter-free model. We determine the
+imprecision-backaction product for our system and provide a roadmap towards
+ground-state cooling of optically levitated nanoparticles.",1812.09875v1
+2019-01-18,Decay of semilinear damped wave equations:cases without geometric control condition,"We consider the semilinear damped wave equation $\partial_{tt}^2
+u(x,t)+\gamma(x)\partial_t u(x,t)=\Delta u(x,t)-\alpha u(x,t)-f(x,u(x,t))$. In
+this article, we obtain the first results concerning the stabilization of this
+semilinear equation in cases where $\gamma$ does not satisfy the geometric
+control condition. When some of the geodesic rays are trapped, the
+stabilization of the linear semigroup is semi-uniform in the sense that
+$\|e^{At}A^{-1}\|\leq h(t)$ for some function $h$ with $h(t)\rightarrow 0$ when
+$t\rightarrow +\infty$. We provide general tools to deal with the semilinear
+stabilization problem in the case where $h(t)$ has a sufficiently fast decay.",1901.06169v1
+2019-02-04,Non-Markovian Effects on Overdamped Systems,"We study the consequences of adopting the memory dependent, non-Markovian,
+physics with the memory-less over-damped approximation usually employed to
+investigate Brownian particles. Due to the finite correlation time scale
+associated with the noise, the stationary behavior of the system is not
+described by the Boltzmann-Gibbs statistics. However, the presence of a very
+weak external white noise can be used to regularize the equilibrium properties.
+Surprisingly, the coupling to another bath effectively restores the dynamical
+aspects missed by the over-damped treatment.",1902.01356v1
+2019-02-06,Stability analysis of a 1D wave equation with a nonmonotone distributed damping,"This paper is concerned with the asymptotic stability analysis of a one
+dimensional wave equation subject to a nonmonotone distributed damping. A
+well-posedness result is provided together with a precise characterization of
+the asymptotic behavior of the trajectories of the system under consideration.
+The well-posedness is proved in the nonstandard L p functional spaces, with p
+$\in$ [2, $\infty$], and relies mostly on some results collected in Haraux
+(2009). The asymptotic behavior analysis is based on an attractivity result on
+a specific infinite-dimensional linear time-variant system.",1902.02050v1
+2019-02-13,"Comment on ""Quantization of the damped harmonic oscillator"" [Serhan et al, J. Math. Phys. 59, 082105 (2018)]","A recent paper [J. Math. Phys. {\bf 59}, 082105 (2018)] constructs a
+Hamiltonian for the (dissipative) damped harmonic oscillator. We point out that
+non-Hermiticity of this Hamiltonian has been ignored to find real discrete
+eigenvalues which are actually non-real. We emphasize that non-Hermiticity in
+Hamiltonian is crucial and it is a quantal signature of dissipation.",1902.04895v1
+2019-02-15,Memory effects teleportation of quantum Fisher information under decoherence,"We have investigated how memory effects on the teleportation of quantum
+Fisher information(QFI) for a single qubit system using a class of X-states as
+resources influenced by decoherence channels with memory, including amplitude
+damping, phase-damping and depolarizing channels. Resort to the definition of
+QFI, we first derive the explicit analytical results of teleportation of QFI
+with respect to weight parameter $\theta$ and phase parameter $\phi$ under the
+decoherence channels. Component percentages, the teleportation of QFI for a
+two-qubit entanglement system has also been addressed. The remarkable
+similarities and differences among these two situations are also analyzed in
+detail and some significant results are presented.",1902.05668v1
+2019-02-23,Uniform decay rates for a suspension bridge with locally distributed nonlinear damping,"We study a nonlocal evolution equation modeling the deformation of a bridge,
+either a footbridge or a suspension bridge. Contrarily to the previous
+literature we prove the asymptotic stability of the considered model with a
+minimum amount of damping which represents less cost of material. The result is
+also numerically proved.",1902.09963v1
+2019-03-01,Spectra of the Dissipative Spin Chain,"This paper generalizes the (0+1)-dimensional spin-boson problem to the
+corresponding (1+1)-dimensional version. Monte Carlo simulation is used to find
+the phase diagram and imaginary time correlation function. The real frequency
+spectrum is recovered by the newly developed P\'ade regression analytic
+continuation method. We find that, as dissipation strength $\alpha$ is
+increased, the sharp quasi-particle spectrum is broadened and the peak
+frequency is lower. According to the behavior of the low frequency spectrum, we
+classify the dynamical phase into three different regions: weakly damped,
+linear $k$-edge, and strongly damped.",1903.00567v1
+2019-03-17,Sensing Kondo correlations in a suspended carbon nanotube mechanical resonator with spin-orbit coupling,"We study electron mechanical coupling in a suspended carbon nanotube (CNT)
+quantum dot device. Electron spin couples to the flexural vibration mode due to
+spin-orbit coupling in the electron tunneling processes. In the weak coupling
+limit, i.e. electron-vibration coupling is much smaller than the electron
+energy scale, the damping and resonant frequency shift of the CNT resonator can
+be obtained by calculating the dynamical spin susceptibility. We find that
+strong spin-flip scattering processes in Kondo regime significantly affect the
+mechanical motion of the carbon nanotube: Kondo effect induces strong damping
+and frequency shift of the CNT resonator.",1903.07049v1
+2019-03-27,Lifespan of semilinear generalized Tricomi equation with Strauss type exponent,"In this paper, we consider the blow-up problem of semilinear generalized
+Tricomi equation. Two blow-up results with lifespan upper bound are obtained
+under subcritical and critical Strauss type exponent. In the subcritical case,
+the proof is based on the test function method and the iteration argument. In
+the critical case, an iteration procedure with the slicing method is employed.
+This approach has been successfully applied to the critical case of semilinear
+wave equation with perturbed Laplacian or the damped wave equation of
+scattering damping case. The present work gives its application to the
+generalized Tricomi equation.",1903.11351v2
+2019-04-01,A remark on semi-linear damped $σ$-evolution equations with a modulus of continuity term in nonlinearity,"In this article, we indicate that under suitable assumptions of a modulus of
+continuity we obtain either the global (in time) existence of small data
+Sobolev solutions or the blow-up result of local (in time) Sobolev solutions to
+semi-linear damped $\sigma$-evolution equations with a modulus of continuity
+term in nonlinearity.",1904.00698v3
+2019-04-05,Critical regularity of nonlinearities in semilinear classical damped wave equations,"In this paper we consider the Cauchy problem for the semilinear damped wave
+equation
+  $u_{tt}-\Delta u + u_t = h(u);\qquad u(0;x) = f(x); \quad u_t(0;x) = g(x);$
+  where $h(s) = |s|^{1+2/n}\mu(|s|)$. Here n is the space dimension and $\mu$
+is a modulus of continuity. Our goal is to obtain sharp conditions on $\mu$ to
+obtain a threshold between global (in time) existence of small data solutions
+(stability of the zerosolution) and blow-up behavior even of small data
+solutions.",1904.02939v1
+2019-04-29,Origin of the DAMPE 1.4 TeV peak,"Recent accurate measurements of cosmic ray electron flux by the Dark Matter
+Particle Explorer (DAMPE) reveal a sharp peak structure near 1.4 TeV, which is
+difficult to explain by standard astrophysical processes. In this letter, we
+propose a simple model that the enhanced dark matter annihilation via the
+$e^+e^-$ channel and with the thermal relic annihilation cross section around
+the current nearest black hole (A0620-00) can satisfactorily account for the
+sharp peak structure. The predicted dark matter mass is $\sim 1.5-3$ TeV.",1904.12418v1
+2019-05-07,Decay estimate for the solution of the evolutionary damped $p$-Laplace equation,"In this note, we study the asymptotic behavior, as $t$ tends to infinity, of
+the solution $u$ to the evolutionary damped $p$-Laplace equation
+\begin{equation*}
+  u_{tt}+a\, u_t =\Delta_p u \end{equation*}
+  with Dirichlet boundary values. Let $u^*$ denote the stationary solution with
+same boundary values, then the $W^{1,p}$-norm of $u(t) - u^{*}$ decays for
+large $t$ like $t^{-\frac{1}{(p-1)p}}$, in the degenerate case $ p > 2$.",1905.03597v2
+2019-05-10,Asymptotic profiles for damped plate equations with rotational inertia terms,"We consider the Cauchy problem for plate equations with rotational inertia
+and frictional damping terms. We will derive asymptotic profiles of the
+solution in L^2-sense as time goes to infinity in the case when the initial
+data have high and low regularity, respectively. Especially, in the low
+regularity case of the initial data one encounters the regularity-loss
+structure of the solutions, and the analysis is more delicate. We employ the
+so-called Fourier splitting method combined with the explicit expression of the
+solutions (high frequency estimates) and the method due to Ikehata (low
+frequency estimates).",1905.04012v1
+2019-05-20,Small perturbations for a Duffing-like evolution equation involving non-commuting operators,"We consider an abstract evolution equation with linear damping, a nonlinear
+term of Duffing type, and a small forcing term. The abstract problem is
+inspired by some models for damped oscillations of a beam subject to external
+loads or magnetic fields, and shaken by a transversal force.
+  The main feature is that very natural choices of the boundary conditions lead
+to equations whose linear part involves two operators that do not commute.
+  We extend to this setting the results that are known in the commutative case,
+namely that for asymptotically small forcing terms all solutions are eventually
+close to the three equilibrium points of the unforced equation, two stable and
+one unstable.",1905.07942v1
+2019-05-30,A study of coherence based measure of quantumness in (non) Markovian channels,"We make a detailed analysis of quantumness for various quantum noise
+channels, both Markovian and non-Markovian. The noise channels considered
+include dephasing channels like random telegraph noise, non-Markovian dephasing
+and phase damping, as well as the non-dephasing channels such as generalized
+amplitude damping and Unruh channels. We make use of a recently introduced
+witness for quantumness based on the square $l_1$ norm of coherence. It is
+found that the increase in the degree of non-Markovianity increases the
+quantumness of the channel.",1905.12872v1
+2019-05-30,Stabilization for vibrating plate with singular structural damping,"We consider the dynamic elasticity equation, modeled by the Euler-Bernoulli
+plate equation, with a locally distributed singular structural (or viscoelastic
+) damping in a boundary domain. Using a frequency domain method combined, based
+on the Burq's result, combined with an estimate of Carleman type we provide
+precise decay estimate showing that the energy of the system decays
+logarithmically as the type goes to the infinity.",1905.13089v1
+2019-06-12,A no-go result for the quantum damped harmonic oscillator,"In this letter we show that it is not possible to set up a canonical
+quantization for the damped harmonic oscillator using the Bateman lagrangian.
+In particular, we prove that no square integrable vacuum exists for the {\em
+natural} ladder operators of the system, and that the only vacua can be found
+as distributions. This implies that the procedure proposed by some authors is
+only formally correct, and requires a much deeper analysis to be made rigorous.",1906.05121v2
+2019-06-26,Mismatched Estimation of Polynomially Damped Signals,"In this work, we consider the problem of estimating the parameters of
+polynomially damped sinusoidal signals, commonly encountered in, for instance,
+spectroscopy. Generally, finding the parameter values of such signals
+constitutes a high-dimensional problem, often further complicated by not
+knowing the number of signal components or their specific signal structures. In
+order to alleviate the computational burden, we herein propose a mismatched
+estimation procedure using simplified, approximate signal models. Despite the
+approximation, we show that such a procedure is expected to yield predictable
+results, allowing for statistically and computationally efficient estimates of
+the signal parameters.",1906.11113v1
+2019-06-27,Temperature-Dependent Lifetimes of Low-Frequency Adsorbate Modes from Non-Equilibrium Molecular Dynamics Simulations,"We present calculations on the damping of a low-frequency adsorbate mode on a
+metal surface, namely the frustrated translation of Na on Cu(100). For the
+first time, vibrational lifetimes of excited adlayers are extracted from
+non-equilibrium molecular dynamics calculations accounting for both the
+phononic and the electronic dissipation channels. The relative contributions of
+the two damping mechanisms, which we show to be additive, are found to disagree
+with textbook predictions. A simple model based on separable harmonic and
+anharmonic contributions is able to semi-quantitatively reproduce the
+temperature dependence of the computed lifetimes.",1906.11776v1
+2019-07-10,Formal expansions in stochastic model for wave turbulence 1: kinetic limit,"We consider the damped/driver (modified) cubic NLS equation on a large torus
+with a properly scaled forcing and dissipation, and decompose its solutions to
+formal series in the amplitude. We study the second order truncation of this
+series and prove that when the amplitude goes to zero and the torus' size goes
+to infinity the energy spectrum of the truncated solutions becomes close to a
+solution of the damped/driven wave kinetic equation. Next we discuss higher
+order truncations of the series.",1907.04531v4
+2019-07-22,Thresholds for low regularity solutions to wave equations with structural damping,"We study the asymptotic behavior of solutions to wave equations with a
+structural damping term \[ u_{tt}-\Delta u+\Delta^2 u_t=0, \qquad
+u(0,x)=u_0(x), \,\,\, u_t(0,x)=u_1(x), \] in the whole space. New thresholds
+are reported in this paper that indicate which of the diffusion wave property
+and the non-diffusive structure dominates in low regularity cases. We develop
+to that end the previous author's research in 2019 where they have proposed a
+threshold that expresses whether the parabolic-like property or the wave-like
+property strongly appears in the solution to some regularity-loss type
+dissipative wave equation.",1907.09299v1
+2019-08-03,Lindblad dynamics of the damped and forced quantum harmonic oscillator,"The quantum dynamics of a damped and forced harmonic oscillator is
+investigated in terms of a Lindblad master equation. Elementary algebraic
+techniques are employed allowing for example to analyze the long time behavior,
+i.e. the quantum limit cycle. The time evolution of various expectation values
+is obtained in closed form as well as the entropy and the Husimi phase space
+distribution. We also discuss the related description in terms of a
+non-Hermitian Hamiltonian.",1908.01187v2
+2019-08-07,Decay estimates for the linear damped wave equation on the Heisenberg group,"This paper is devoted to the derivation of $L^2$ - $L^2$ decay estimates for
+the solution of the homogeneous linear damped wave equation on the Heisenberg
+group $\mathbf{H}_n$, for its time derivative and for its horizontal gradient.
+Moreover, we consider the improvement of these estimates when further
+$L^1(\mathbf{H}_n)$ regularity is required for the Cauchy data. Our approach
+will rely strongly on the group Fourier transform of $\mathbf{H}_n$ and on the
+properties of the Hermite functions that form a maximal orthonormal system for
+$L^2(\mathbb{R}^n)$ of eigenfunctions of the harmonic oscillator.",1908.02657v1
+2019-08-08,Critical exponent of Fujita-type for the semilinear damped wave equation on the Heisenberg group with power nonlinearity,"In this paper, we consider the Cauchy problem for the semilinear damped wave
+equation on the Heisenberg group with power nonlinearity. We prove that the
+critical exponent is the Fujita exponent $p_{\mathrm{Fuj}}(\mathscr{Q}) = 1+2 /
+\mathscr{Q}$, where $\mathscr{Q}$ is the homogeneous dimension of the
+Heisenberg group. On the one hand, we will prove the global existence of small
+data solutions for $p >p_{\mathrm{Fuj}}(\mathscr{Q})$ in an exponential
+weighted energy space. On the other hand, a blow-up result for $1 < p \leq
+p_{\mathrm{Fuj}}(\mathscr{Q})$ under certain integral sign assumptions for the
+Cauchy data by using the test function method.",1908.02989v1
+2019-09-01,Invariant measures for stochastic damped 2D Euler equations,"We study the two-dimensional Euler equations, damped by a linear term and
+driven by an additive noise. The existence of weak solutions has already been
+studied; pathwise uniqueness is known for solutions that have vorticity in
+$L^\infty$. In this paper, we prove the Markov property and then the existence
+of an invariant measure in the space $L^\infty$ by means of a
+Krylov-Bogoliubov's type method, working with the weak$\star$ and the bounded
+weak$\star$ topologies in $L^\infty$.",1909.00424v2
+2019-09-03,A blow-up result for semi-linear structurally damped $σ$-evolution equations,"We would like to prove a blow-up result for semi-linear structurally damped
+$\sigma$-evolution equations, where $\sigma \ge 1$ and $\delta\in [0,\sigma)$
+are assumed to be any fractional numbers. To deal with the fractional Laplacian
+operators $(-\Delta)^\sigma$ and $(-\Delta)^\delta$ as well-known non-local
+operators, in general, it seems difficult to apply the standard test function
+method directly. For this reason, in this paper we shall construct new test
+functions to overcome this difficulty.",1909.01181v1
+2019-09-09,Action Functional for a Particle with Damping,"In this brief report we discuss the action functional of a particle with
+damping, showing that it can be obtained from the dissipative equation of
+motion through a modification which makes the new dissipative equation
+invariant for time reversal symmetry. This action functional is exactly the
+effective action of Caldeira-Leggett model but, in our approach, it is derived
+without the assumption that the particle is weakly coupled to a bath of
+infinite harmonic oscillators.",1909.03694v2
+2019-09-11,Equilibrium radiation in a plasma medium with spatial and frequency dispersion,"Examination of equilibrium radiation in plasma media shows that the spectral
+energy distribution of such radiation is different from the Planck equilibrium
+radiation. Using the approach of quantum electrodynamics the general relation
+for the spectral energy density of equilibrium radiation in a system of charged
+particles is found. The obtained result takes into account the influence of
+plasma on equilibrium radiation through the explicit transverse dielectric
+permittivity which takes into account spatial and frequency dispersion, as well
+as the finite collisional damping. For the limiting case of an infinitesimal
+damping the result coincides with the known expression.",1909.08056v1
+2019-10-14,Blow-up of solutions to semilinear strongly damped wave equations with different nonlinear terms in an exterior domain,"In this paper, we consider the initial boundary value problem in an exterior
+domain for semilinear strongly damped wave equations with power nonlinear term
+of the derivative-type $|u_t|^q$ or the mixed-type $|u|^p+|u_t|^q$, where
+$p,q>1$. On one hand, employing the Banach fixed-point theorem we prove local
+(in time) existence of mild solutions. On the other hand, under some conditions
+for initial data and the exponents of power nonlinear terms, the blow-up
+results are derived by applying the test function method.",1910.05981v1
+2019-11-03,Linear Inviscid Damping in Sobolev and Gevrey Spaces,"In a recent article Jia established linear inviscid damping in Gevrey
+regularity for compactly supported Gevrey regular shear flows in a finite
+channel, which is of great interest in view of existing nonlinear results. In
+this article we provide an alternative very short proof of stability in Gevrey
+regularity as a consequence of stability in high Sobolev regularity. Here, we
+consider both the setting of a finite channel with compactly supported
+perturbations and of an infinite channel without this restriction. Furthermore,
+we consider the setting where perturbations vanish only of finite order.",1911.00880v1
+2019-11-03,A global existence result for two-dimensional semilinear strongly damped wave equation with mixed nonlinearity in an exterior domain,"We study two-dimensional semilinear strongly damped wave equation with mixed
+nonlinearity $|u|^p+|u_t|^q$ in an exterior domain, where $p,q>1$. Assuming the
+smallness of initial data in exponentially weighted spaces and some conditions
+on powers of nonlinearity, we prove global (in time) existence of small data
+energy solution with suitable higher regularity by using a weighted energy
+method.",1911.00899v1
+2019-11-05,Critical exponent for a weakly coupled system of semi-linear $σ$-evolution equations with frictional damping,"We are interested in studying the Cauchy problem for a weakly coupled system
+of semi-linear $\sigma$-evolution equations with frictional damping. The main
+purpose of this paper is two-fold. We would like to not only prove the global
+(in time) existence of small data energy solutions but also indicate the
+blow-up result for Sobolev solutions when $\sigma$ is assumed to be any
+fractional number.",1911.01946v1
+2019-11-11,Existence and nonexistence of global solutions for a structurally damped wave system with power nonlinearities,"Our interest itself of this paper is strongly inspired from an open problem
+in the paper [1] published by D'Abbicco. In this article, we would like to
+study the Cauchy problem for a weakly coupled system of semi-linear
+structurally damped wave equations. Main goal is to find the threshold, which
+classifies the global (in time) existence of small data solutions or the
+nonexistence of global solutions under the growth condition of the
+nonlinearities.",1911.04412v1
+2019-11-15,Some $L^1$-$L^1$ estimates for solutions to visco-elastic damped $σ$-evolution models,"This note is to conclude $L^1-L^1$ estimates for solutions to the following
+Cauchy problem for visco-elastic damped $\sigma$-evolution models:
+\begin{equation} \begin{cases} u_{tt}+ (-\Delta)^\sigma u+ (-\Delta)^\sigma u_t
+= 0, &\quad x\in \mathbb{R}^n,\, t \ge 0, \\ u(0,x)= u_0(x),\quad
+u_t(0,x)=u_1(x), &\quad x\in \mathbb{R}^n, \label{pt1.1} \end{cases}
+\end{equation} where $\sigma> 1$, in all space dimensions $n\ge 1$.",1911.06563v1
+2019-11-22,Long-time asymptotics for a coupled thermoelastic plate-membrane system,"In this paper we consider a transmission problem for a system of a
+thermoelastic plate with (or without) rotational inertia term coupled with a
+membrane with different variants of damping for the plate and/or the membrane.
+We prove well-posedness of the problem and higher regularity of the solution
+and study the asymptotic behaviour of the solution, depending on the damping
+and on the presence of the rotational term.",1911.10161v1
+2019-11-28,Tikhonov regularization of a second order dynamical system with Hessian driven damping,"We investigate the asymptotic properties of the trajectories generated by a
+second-order dynamical system with Hessian driven damping and a Tikhonov
+regularization term in connection with the minimization of a smooth convex
+function in Hilbert spaces. We obtain fast convergence results for the function
+values along the trajectories. The Tikhonov regularization term enables the
+derivation of strong convergence results of the trajectory to the minimizer of
+the objective function of minimum norm.",1911.12845v2
+2019-12-15,"Negative mobility, sliding and delocalization for stochastic networks","We consider prototype configurations for quasi-one-dimensional stochastic
+networks that exhibit negative mobility, meaning that current decreases or even
+reversed as the bias is increased. We then explore the implications of
+disorder. In particular we ask whether lower and upper bias thresholds restrict
+the possibility to witness non-zero current (sliding and anti-sliding
+transitions respectively), and whether a delocalization effect manifest itself
+(crossover from over-damped to under-damped relaxation). In the latter context
+detailed analysis of the relaxation spectrum as a function of the bias is
+provided for both on-chain and off-chain disorder.",1912.07059v2
+2019-12-23,On a damped Szego equation (with an appendix in collaboration with Christian Klein),"We investigate how damping the lowest Fourier mode modifies the dynamics of
+the cubic Szeg{\""o} equation. We show that there is a nonempty open subset of
+initial data generating trajec-tories with high Sobolev norms tending to
+infinity. In addition, we give a complete picture of this phenomenon on a
+reduced phase space of dimension 6. An appendix is devoted to numerical
+simulations supporting the generalisation of this picture to more general
+initial data.",1912.10933v1
+2020-01-29,The long time behavior and the rate of convergence of symplectic convex algorithms obtained via splitting discretizations of inertial damping systems,"In this paper we propose new numerical algorithms in the setting of
+unconstrained optimization problems and we study the rate of convergence in the
+iterates of the objective function. Furthermore, our algorithms are based upon
+splitting and symplectic methods and they preserve the energy properties of the
+inherent continuous dynamical system that contains a Hessian perturbation. At
+the same time, we show that Nesterov gradient method is equivalent to a
+Lie-Trotter splitting applied to a Hessian driven damping system. Finally, some
+numerical experiments are presented in order to validate the theoretical
+results.",2001.10831v2
+2020-02-05,Long-time asymptotics of the one-dimensional damped nonlinear Klein-Gordon equation,"For the one-dimensional nonlinear damped Klein-Gordon equation \[
+\partial_{t}^{2}u+2\alpha\partial_{t}u-\partial_{x}^{2}u+u-|u|^{p-1}u=0 \quad
+\mbox{on $\mathbb{R}\times\mathbb{R}$,}\] with $\alpha>0$ and $p>2$, we prove
+that any global finite energy solution either converges to $0$ or behaves
+asymptotically as $t\to \infty$ as the sum of $K\geq 1$ decoupled solitary
+waves. In the multi-soliton case $K\geq 2$, the solitary waves have alternate
+signs and their distances are of order $\log t$.",2002.01826v1
+2020-02-11,Distributional Solutions of the Damped Wave Equation,"This work presents results on solutions of the one-dimensional damped wave
+equation, also called telegrapher's equation, when the initial conditions are
+general distributions, not only functions. We make a complete deduction of its
+fundamental solutions, both for positive and negative times. To obtain them we
+use only self-similarity arguments and distributional calculus, making no use
+of Fourier or Laplace transforms. We next use these fundamental solutions to
+prove both the existence and the uniqueness of solutions to the distributional
+initial value problem. As applications we recover the semigroup property for
+initial data in classical function spaces and also the probability distribution
+function for a certain financial model of evolution of prices.",2002.04249v2
+2020-02-13,Description of the wavevector dispersion of surface plasmon-phonon-polaritons,"We reported here the results of the calculations of wavevector dispersion of
+oscillations frequencies, $\omega'(k)$, and damping $\omega''(k)$ of the
+surface plasmon phonon polaritons (\mbox{SPPhP}) for the heavy-doped GaN
+sample. We showed that $\omega'(k)$- dependence consists of the three branches
+with the specific anticrossing behavior due to the interaction of surface
+plasmon polariton (SPP) with surface phonon polariton(SPhP). The strong
+renormalization of the damping $\omega''(k)$ in the vicinity of the
+anticrossing region was found. The obtained dispersions of the $\omega'(k)$ and
+$\omega''(k)$ were applied for the analytical analysis of exact electrodynamic
+simulation of the resonant behavior of the reflectivity spectrum of the n-GaN
+grating.",2002.05473v1
+2020-03-20,The Cauchy problem of the semilinear second order evolution equation with fractional Laplacian and damping,"In the present paper, we prove time decay estimates of solutions in weighted
+Sobolev spaces to the second order evolution equation with fractional Laplacian
+and damping for data in Besov spaces. Our estimates generalize the estimates
+obtained in the previous studies. The second aim of this article is to apply
+these estimates to prove small data global well-posedness for the Cauchy
+problem of the equation with power nonlinearities. Especially, the estimates
+obtained in this paper enable us to treat more general conditions on the
+nonlinearities and the spatial dimension than the results in the previous
+studies.",2003.09239v1
+2020-03-31,Time-Asymptotics of Physical Vacuum Free Boundaries for Compressible Inviscid Flows with Damping,"In this paper, we prove the leading term of time-asymptotics of the moving
+vacuum boundary for compressible inviscid flows with damping to be that for
+Barenblatt self-similar solutions to the corresponding porous media equations
+obtained by simplifying momentum equations via Darcy's law plus the possible
+shift due to the movement of the center of mass, in the one-dimensional and
+three-dimensional spherically symmetric motions, respectively. This gives a
+complete description of the large time asymptotic behavior of solutions to the
+corresponding vacuum free boundary problems. The results obtained in this paper
+are the first ones concerning the large time asymptotics of physical vacuum
+boundaries for compressible inviscid fluids, to the best of our knowledge.",2003.14072v2
+2020-04-13,Landau damping for analytic and Gevrey data,"In this paper, we give an elementary proof of the nonlinear Landau damping
+for the Vlasov-Poisson system near Penrose stable equilibria on the torus
+$\mathbb{T}^d \times \mathbb{R}^d$ that was first obtained by Mouhot and
+Villani in \cite{MV} for analytic data and subsequently extended by Bedrossian,
+Masmoudi, and Mouhot \cite{BMM} for Gevrey-$\gamma$ data,
+$\gamma\in(\frac13,1]$. Our proof relies on simple pointwise resolvent
+estimates and a standard nonlinear bootstrap analysis, using an ad-hoc family
+of analytic and Gevrey-$\gamma$ norms.",2004.05979v3
+2020-04-16,Strichartz estimates for mixed homogeneous surfaces in three dimensions,"We obtain sharp mixed norm Strichartz estimates associated to mixed
+homogeneous surfaces in $\mathbb{R}^3$. Both cases with and without a damping
+factor are considered. In the case when a damping factor is considered our
+results yield a wide generalization of a result of Carbery, Kenig, and Ziesler
+[CKZ13]. The approach we use is to first classify all possible singularities
+locally, after which one can tackle the problem by appropriately modifying the
+methods from the paper of Ginibre and Velo [GV92], and by using the recently
+developed methods by Ikromov and M\""uller [IM16].",2004.07751v1
+2020-04-17,Critical exponent for semi-linear structurally damped wave equation of derivative type,"Main purpose of this paper is to study the following semi-linear structurally
+damped wave equation with nonlinearity of derivative type: $$u_{tt}- \Delta u+
+\mu(-\Delta)^{\sigma/2} u_t= |u_t|^p,\quad u(0,x)= u_0(x),\quad
+u_t(0,x)=u_1(x),$$ with $\mu>0$, $n\geq1$, $\sigma \in (0,2]$ and $p>1$. In
+particular, we are going to prove the non-existence of global weak solutions by
+using a new test function and suitable sign assumptions on the initial data in
+both the subcritical case and the critical case.",2004.08486v2
+2020-04-29,Exponential decay for damped Klein-Gordon equations on asymptotically cylindrical and conic manifolds,"We study the decay of the global energy for the damped Klein-Gordon equation
+on non-compact manifolds with finitely many cylindrical and subconic ends up to
+bounded perturbation. We prove that under the Geometric Control Condition, the
+decay is exponential, and that under the weaker Network Control Condition, the
+decay is logarithmic, by developing the global Carleman estimate with multiple
+weights.",2004.13894v2
+2020-05-06,Zero-dimensional models for gravitational and scalar QED decoherence,"We investigate the dynamics of two quantum mechanical oscillator system-bath
+toy models obtained by truncating to zero spatial dimensions linearized gravity
+coupled to a massive scalar field and scalar QED. The scalar-gravity toy model
+maps onto the phase damped oscillator, while the scalar QED toy model
+approximately maps onto an oscillator system subject to two-photon damping. The
+toy models provide potentially useful insights into solving for open system
+quantum dynamics relevant to the full scalar QED and weak gravitational field
+systems, in particular operational probes of the decoherence for initial scalar
+field system superposition states.",2005.02554v2
+2020-05-16,On the asymptotic stability of wave equations coupled by velocities of anti-symmetric type,"In this paper, we study the asymptotic stability of two wave equations
+coupled by velocities of anti-symmetric type via only one damping. We adopt the
+frequency domain method to prove that the system with smooth initial data is
+logarithmically stable, provided that the coupling domain and the damping
+domain intersect each other. Moreover, we show, by an example, that this
+geometric assumption of the intersection is necessary for 1-D case.",2005.07977v2
+2020-05-27,On the blow-up of solutions to semilinear damped wave equations with power nonlinearity in compact Lie groups,"In this note, we prove a blow-up result for the semilinear damped wave
+equation in a compact Lie group with power nonlinearity $|u|^p$ for any $p>1$,
+under suitable integral sign assumptions for the initial data, by using an
+iteration argument. A byproduct of this method is the upper bound estimate for
+the lifespan of a local in time solution. As a preliminary result, a local (in
+time) existence result is proved in the energy space via Fourier analysis on
+compact Lie groups.",2005.13479v2
+2020-06-13,On the well-posedness of the damped time-harmonic Galbrun equation and the equations of stellar oscillations,"We study the time-harmonic Galbrun equation describing the propagation of
+sound in the presence of a steady background flow. With additional rotational
+and gravitational terms these equations are also fundamental in helio- and
+asteroseismology as a model for stellar oscillations. For a simple damping
+model we prove well-posedness of these equations, i.e. uniqueness, existence,
+and stability of solutions under mild conditions on the parameters (essentially
+subsonic flows). The main tool of our analysis is a generalized Helmholtz
+decomposition.",2006.07658v1
+2020-06-22,Prediction of short time qubit readout via measurement of the next quantum jump of a coupled damped driven harmonic oscillator,"The dynamics of the next quantum jump for a qubit [two level system] coupled
+to a readout resonator [damped driven harmonic oscillator] is calculated. A
+quantum mechanical treatment of readout resonator reveals non exponential short
+time behavior which could facilitate detection of the state of the qubit faster
+than the resonator lifetime.",2006.11950v1
+2020-07-08,The interplay of critical regularity of nonlinearities in a weakly coupled system of semi-linear damped wave equations,"We would like to study a weakly coupled system of semi-linear classical
+damped wave equations with moduli of continuity in nonlinearities whose powers
+belong to the critical curve in the $p-q$ plane. The main goal of this paper is
+to find out the sharp conditions of these moduli of continuity which classify
+between global (in time) existence of small data solutions and finite time
+blow-up of solutions.",2007.04157v1
+2020-07-09,Semi-uniform stability of operator semigroups and energy decay of damped waves,"Only in the last fifteen years or so has the notion of semi-uniform
+stability, which lies between exponential stability and strong stability,
+become part of the asymptotic theory of $C_0$-semigroups. It now lies at the
+very heart of modern semigroup theory. After briefly reviewing the notions of
+exponential and strong stability, we present an overview of some of the best
+known (and often optimal) abstract results on semi-uniform stability. We go on
+to indicate briefly how these results can be applied to obtain (sometimes
+optimal) rates of energy decay for certain damped second-order Cauchy problems.",2007.04711v1
+2020-07-10,Quasi-periodic travelling waves for a class of damped beams on rectangular tori,"This article concerns a class of beam equations with damping on rectangular
+tori. When the generators satisfy certain relationship, by excluding some value
+of two model parameters, we prove that such models admit small amplitude
+quasi-periodic travelling wave solutions with two frequencies, which are
+continuations of two rotating wave solutions with one frequency. This result
+holds not only for an isotropic torus, but also for an anisotropic torus. The
+proof is mainly based on a Lyapunov--Schmidt reduction together with the
+implicit function theorem.",2007.05154v1
+2020-07-24,A Framework to Control Inter-Area Oscillations with Local Measurement,"Inter-area oscillations in power system limit of power transfer capability
+though tie-lines. For stable operation, wide-area power system stabilizers are
+deployed to provide sufficient damping. However, as the feedback is through a
+communication network, it brings challenges such as additional communication
+layer and cybersecurity issues. To address this, a framework for synthesizing
+remote signal from local measurement as feedback in the wide-area power system
+stabilizer is proposed. The remote signal is synthesized using different
+variants of observers in a case study of two-area benchmark system. The
+proposed framework can improve the damping of inter-area oscillations for
+static output feedback controller. The presented framework should help to
+design attack-resilient controller design in smart grid.",2007.12426v1
+2020-08-17,Dynamics of spatially indistinguishable particles and entanglement protection,"We provide a general framework which allows one to obtain the dynamics of $N$
+noninteracting spatially indistinguishable particles locally coupled to
+separated environments. The approach is universal, being valid for both bosons
+and fermions and for any type of system-environment interaction. It is then
+applied to study the dynamics of two identical qubits under paradigmatic
+Markovian noises, such as phase damping, depolarizing and amplitude damping. We
+find that spatial indistinguishability of identical qubits is a controllable
+intrinsic property of the system which protects quantum entanglement against
+detrimental noise.",2008.07471v1
+2020-09-02,Discriminating qubit amplitude damping channels,"We address the issue of the discrimination between two-qubit amplitude
+damping channels by exploring several strategies. For the single-shot, we show
+that the excited state does not always give the optimal input, and that side
+entanglement assistance has limited benefit. On the contrary, feedback
+assistance from the environment is more beneficial. For the two-shot, we prove
+the in-utility of entangled inputs. Then focusing on individual (local)
+measurements, we find the optimal adaptive strategy.",2009.01000v3
+2020-09-03,Asymptotic behavior of 2D stably stratified fluids with a damping term in the velocity equation,"This article is concerned with the asymptotic behavior of the two-dimensional
+inviscid Boussinesq equations with a damping term in the velocity equation.
+Precisely, we provide the time-decay rates of the smooth solutions to that
+system. The key ingredient is a careful analysis of the Green kernel of the
+linearized problem in Fourier space, combined with bilinear estimates and
+interpolation inequalities for handling the nonlinearity.",2009.01578v2
+2020-08-05,The perturbational stability of the Schr$\ddot{o}$dinger equation,"By using the Wigner transform, it is shown that the nonlinear
+Schr$\ddot{\textmd{o}}$dinger equation can be described, in phase space, by a
+kinetic theory similar to the Vlasov equation which is used for describing a
+classical collisionless plasma. In this paper we mainly show Landau damping in
+the quantum sense, namely,quantum Landau damping exists for the Wigner-Poisson
+system. At the same time, we also prove the existence and the stability of the
+nonlinear Schr$\ddot{\textmd{o}}$dinger equation under the quantum stability
+assumption.",2009.09855v1
+2020-10-12,Long time behavior of solutions for a damped Benjamin-Ono equation,"We consider the Benjamin-Ono equation on the torus with an additional damping
+term on the smallest Fourier modes (cos and sin). We first prove global
+well-posedness of this equation in $L^2_{r,0}(\mathbb{T})$. Then, we describe
+the weak limit points of the trajectories in $L^2_{r,0}(\mathbb{T})$ when time
+goes to infinity, and show that these weak limit points are strong limit
+points. Finally, we prove the boundedness of higher-order Sobolev norms for
+this equation. Our key tool is the Birkhoff map for the Benjamin-Ono equation,
+that we use as an adapted nonlinear Fourier transform.",2010.05520v1
+2020-10-18,Classical limit of quantum mechanics for damped driven oscillatory systems: Quantum-classical correspondence,"The investigation of quantum-classical correspondence may lead to gain a
+deeper understanding of the classical limit of quantum theory. We develop a
+quantum formalism on the basis of a linear-invariant theorem, which gives an
+exact quantum-classical correspondence for damped oscillatory systems that are
+perturbed by an arbitrary force. Within our formalism, the quantum trajectory
+and expectation values of quantum observables are precisely coincide with their
+classical counterparts in the case where we remove the global quantum constant
+h from their quantum results. In particular, we illustrate the correspondence
+of the quantum energy with the classical one in detail.",2010.08971v1
+2020-10-21,Initial boundary value problem for a strongly damped wave equation with a general nonlinearity,"In this paper, a strongly damped semilinear wave equation with a general
+nonlinearity is considered. With the help of a newly constructed auxiliary
+functional and the concavity argument, a general finite time blow-up criterion
+is established for this problem. Furthermore, the lifespan of the weak solution
+is estimated from both above and below. This partially extends some results
+obtained in recent literatures and sheds some light on the similar effect of
+power type nonlinearity and logarithmic nonlinearity on finite time blow-up of
+solutions to such problems.",2010.10696v1
+2020-10-21,MRI Image Recovery using Damped Denoising Vector AMP,"Motivated by image recovery in magnetic resonance imaging (MRI), we propose a
+new approach to solving linear inverse problems based on iteratively calling a
+deep neural-network, sometimes referred to as plug-and-play recovery. Our
+approach is based on the vector approximate message passing (VAMP) algorithm,
+which is known for mean-squared error (MSE)-optimal recovery under certain
+conditions. The forward operator in MRI, however, does not satisfy these
+conditions, and thus we design new damping and initialization schemes to help
+VAMP. The resulting DD-VAMP++ algorithm is shown to outperform existing
+algorithms in convergence speed and accuracy when recovering images from the
+fastMRI database for the practical case of Cartesian sampling.",2010.11321v1
+2020-11-05,Mathematical modelling of an unstable bent flow using the selective frequency damping method,"The selective frequency damping method was applied to a bent flow. The method
+was used in an adaptive formulation. The most dangerous frequency was
+determined by solving an eigenvalue problem. It was found that one of the
+patterns, steady-state or pulsating, may exist at some relatively high Reynolds
+numbers. The periodic flow occurs due to the instability of the steady-state
+flow. This numerical method is easy to use but requires a great deal of time
+for calculations.",2011.02646v1
+2020-11-04,"The ""Dark disk"" model in the light of DAMPE experiment","There are a lot of models considering the Dark Matter (DM) to be the origin
+of cosmic ray (CR) positron excess. However, they face an obstacle in the form
+of gamma-rays. Simple DM models tend to overproduce gamma-rays, leading to
+contradiction with isotropic gamma-ray background (IGRB). The <<dark disk>>
+model has been proposed to alleviate this contradiction. This work considers
+results of DAMPE experiment in the framework of the disk model. It is obtained
+that such a framework allows improving data fit considerably.",2011.04425v2
+2020-12-15,On the stability of Bresse system with one discontinuous local internal Kelvin-Voigt damping on the axial force,"In this paper, we investigate the stabilization of a linear Bresse system
+with one discontinuous local internal viscoelastic damping of Kelvin-Voigt type
+acting on the axial force, under fully Dirichlet boundary conditions. First,
+using a general criteria of Arendt-Batty, we prove the strong stability of our
+system. Finally, using a frequency domain approach combined with the multiplier
+method, we prove that the energy of our system decays polynomially with
+different rates.",2012.08219v1
+2020-12-28,An efficient method for approximating resonance curves of weakly-damped nonlinear mechanical systems,"A method is presented for tracing the locus of a specific peak in the
+frequency response under variation of a parameter. It is applicable to
+periodic, steady-state vibrations of harmonically forced nonlinear mechanical
+systems. It operates in the frequency domain and its central idea is to assume
+a constant phase lag between forcing and response. The method is validated for
+a two-degree-of-freedom oscillator with cubic spring and a bladed disk with
+shroud contact. The method provides superior computational efficiency, but is
+limited to weakly-damped systems. Finally, the capability to reveal isolated
+solution branches is highlighted.",2012.14458v1
+2021-01-16,Convergence of non-autonomous attractors for subquintic weakly damped wave equation,"We study the non-autonomous weakly damped wave equation with subquintic
+growth condition on the nonlinearity. Our main focus is the class of
+Shatah--Struwe solutions, which satisfy the Strichartz estimates and are
+coincide with the class of solutions obtained by the Galerkin method. For this
+class we show the existence and smoothness of pullback, uniform, and cocycle
+attractors and the relations between them. We also prove that these
+non-autonomous attractors converge upper-semicontinuously to the global
+attractor for the limit autonomous problem if the time-dependent nonlinearity
+tends to time independent function in an appropriate way.",2101.06523v1
+2021-01-20,A Damped Newton Algorithm for Generated Jacobian Equations,"Generated Jacobian Equations have been introduced by Trudinger [Disc. cont.
+dyn. sys (2014), pp. 1663-1681] as a generalization of Monge-Amp{\`e}re
+equations arising in optimal transport. In this paper, we introduce and study a
+damped Newton algorithm for solving these equations in the semi-discrete
+setting, meaning that one of the two measures involved in the problem is
+finitely supported and the other one is absolutely continuous. We also present
+a numerical application of this algorithm to the near-field parallel refractor
+problem arising in non-imaging problems.",2101.08080v1
+2021-02-04,Global existence results for semi-linear structurally damped wave equations with nonlinear convection,"In this paper, we consider the Cauchy problem for semi-linear wave equations
+with structural damping term $\nu (-\Delta)^2 u_t$, where $\nu >0$ is a
+constant. As being mentioned in [8,10], the linear principal part brings both
+the diffusion phenomenon and the regularity loss of solutions. This implies
+that, for the nonlinear problems, the choice of solution spaces plays an
+important role to obtain global solutions with sharp decay properties in time.
+Our main purpose of this paper is to prove the global (in time) existence of
+solutions for the small data and their decay properties for the supercritical
+nonlinearities.",2102.02445v2
+2021-02-15,"Piezoelectric beam with magnetic effect, time-varying delay and time-varying weights","The main result of this work is to obtain the exponential decay of the
+solutions of a piezoelectric beam model with magnetic effect and delay term.
+The dampings are inserted into the equation of longitudinal displacement. The
+terms of damping, whose weight associated with them varies over time, are of
+the friction type, and one of them has delay. This work will also address the
+issue of existence and uniqueness of solution for the model.",2102.07538v1
+2021-02-23,Effects of ground-state correlations on damping of giant dipole resonaces in $LS$ closed shell nuclei,"The effects of ground-state correlations on the damping of isovector giant
+dipole resonances in $LS$ closed shell nuclei $^{16}$O and $^{40}$Ca are
+studied using extended random-phase-approximation (RPA) approaches derived from
+the time-dependent density-matrix theory. It is pointed out that unconventional
+two-body amplitudes of one particle--three hole and three particle--one hole
+types which are neglected in most extended RPA theories play an important role
+in the fragmentation of isovector dipole strength.",2102.11505v2
+2021-03-01,On a damped nonlinear beam equation,"In this note we analyze the large time behavior of solutions to an
+initial/boundary problem involving a damped nonlinear beam equation. We show
+that under physically realistic conditions on the nonlinear terms in the
+equation of motion the energy is a decreasing function of time and solutions
+converge to a stationary solution with respect to a desirable norm.",2103.00969v3
+2021-03-23,Fast convergence of dynamical ADMM via time scaling of damped inertial dynamics,"In this paper, we propose in a Hilbertian setting a second-order
+time-continuous dynamic system with fast convergence guarantees to solve
+structured convex minimization problems with an affine constraint. The system
+is associated with the augmented Lagrangian formulation of the minimization
+problem. The corresponding dynamics brings into play three general time-varying
+parameters, each with specific properties, and which are respectively
+associated with viscous damping, extrapolation and temporal scaling. By
+appropriately adjusting these parameters, we develop a Lyapunov analysis which
+provides fast convergence properties of the values and of the feasibility gap.
+These results will naturally pave the way for developing corresponding
+accelerated ADMM algorithms, obtained by temporal discretization.",2103.12675v1
+2021-03-29,Comparison between the Cauchy problem and the scattering problem for the Landau damping in the Vlasov-HMF equation,"We analyze the analytic Landau damping problem for the Vlasov-HMF equation,
+by fixing the asymptotic behavior of the solution. We use a new method for this
+""scattering problem"", closer to the one used for the Cauchy problem. In this
+way we are able to compare the two results, emphasizing the different influence
+of the plasma echoes in the two approaches. In particular, we prove a
+non-perturbative result for the scattering problem.",2103.15932v2
+2021-04-06,Realising Einstein's mirror: Optomechanical damping with a thermal photon gas,"In 1909 Einstein described the thermalization of a mirror within a blackbody
+cavity by collisions with thermal photons. While the time to thermalize the
+motion of even a microscale or nanoscale object is so long that it is not
+feasible, we show that it is using the high intensity light from an amplified
+thermal light source with a well-defined chemical potential. We predict damping
+of the center-of mass motion due to this effect on times scales of seconds for
+small optomechanical systems, such as levitated nanoparticles, allowing
+experimental observation.",2104.02708v2
+2021-04-12,The pressureless damped Euler-Riesz equations,"In this paper, we analyze the pressureless damped Euler-Riesz equations posed
+in either $\mathbb{R}^d$ or $\mathbb{T}^d$. We construct the global-in-time
+existence and uniqueness of classical solutions for the system around a
+constant background state. We also establish large-time behaviors of classical
+solutions showing the solutions towards the equilibrium as time goes to
+infinity. For the whole space case, we first show the algebraic decay rate of
+solutions under additional assumptions on the initial data compared to the
+existence theory. We then refine the argument to have the exponential decay
+rate of convergence even in the whole space. In the case of the periodic
+domain, without any further regularity assumptions on the initial data, we
+provide the exponential convergence of solutions.",2104.05153v1
+2021-04-12,Fractional time stepping and adjoint based gradient computation in an inverse problem for a fractionally damped wave equation,"In this paper we consider the inverse problem of identifying the initial data
+in a fractionally damped wave equation from time trace measurements on a
+surface, as relevant in photoacoustic or thermoacoustic tomography. We derive
+and analyze a time stepping method for the numerical solution of the
+corresponding forward problem. Moreover, to efficiently obtain reconstructions
+by minimizing a Tikhonov regularization functional (or alternatively, by
+computing the MAP estimator in a Bayesian approach), we develop an adjoint
+based scheme for gradient computation. Numerical reconstructions in two space
+dimensions illustrate the performance of the devised methods.",2104.05577v1
+2021-04-15,Explaining Neptune's Eccentricity,"Early migration damped Neptune's eccentricity. Here, we assume that the
+damped value was much smaller than the value observed today, and show that the
+closest flyby of $\sim 0.1 \; \mathrm{M_{\odot}}$ star over $\sim 4.5
+\mathrm{\; Gyr}$ in the field, at a distance of $\sim 10^3 \mathrm{\; AU}$
+would explain the value of Neptune's eccentricity observed today.",2104.07672v3
+2021-04-17,Lifespan estimates for wave equations with damping and potential posed on asymptotically Euclidean manifolds,"In this work, we investigate the problem of finite time blow up as well as
+the upper bound estimates of lifespan for solutions to small-amplitude
+semilinear wave equations with time dependent damping and potential, and mixed
+nonlinearities $c_1 |u_t|^p+c_2 |u|^q$, posed on asymptotically Euclidean
+manifolds, which is related to both the Strauss conjecture and the Glassey
+conjecture.",2104.08497v2
+2021-06-02,Convergent dynamics of optimal nonlinear damping control,"Following Demidovich's concept and definition of convergent systems, we
+analyze the optimal nonlinear damping control, recently proposed [1] for the
+second-order systems. Targeting the problem of output regulation,
+correspondingly tracking of $\mathcal{C}^1$-trajectories, it is shown that all
+solutions of the control system are globally uniformly asymptotically stable.
+The existence of the unique limit solution in the origin of the control error
+and its time derivative coordinates are shown in the sense of Demidovich's
+convergent dynamics. Explanative numerical examples are also provided along
+with analysis.",2106.00962v1
+2021-06-26,Role of Dissipation on the Stability of a Parametrically Driven Quantum Harmonic Oscillator,"We study the dissipative dynamics of a single quantum harmonic oscillator
+subjected to a parametric driving with in an effective Hamiltonian approach.
+Using Liouville von Neumann approach, we show that the time evolution of a
+parametrically driven dissipative quantum oscillator has a strong connection
+with the classical damped Mathieu equation. Based on the numerical analysis of
+the Monodromy matrix, we demonstrate that the dynamical instability generated
+by the parametric driving are reduced by the effect of dissipation. Further, we
+obtain a closed relationship between the localization of the Wigner function
+and the stability of the damped Mathieu equation.",2106.14018v1
+2021-07-29,Global existence for damped $σ$-evolution equations with nonlocal nonlinearity,"In this research, we would like to study the global (in time) existence of
+small data solutions to the following damped $\sigma$-evolution equations with
+nonlocal (in space) nonlinearity: \begin{equation*}
+\partial_{t}^{2}u+(-\Delta)^{\sigma}u+\partial_{t}u+(-\Delta)^{\sigma}\partial_{t}u=I_{\alpha}(|u|^{p}),
+\ \ t>0, \ \ x\in \mathbb{R}^{n}, \end{equation*} where $\sigma\geq1$, $p>1$
+and $I_{\alpha}$ is the Riesz potential of power nonlinearity $|u|^{p}$ for any
+$\alpha\in (0,n)$. More precisely, by using the $(L^{m}\cap L^{2})-L^{2}$ and
+$L^{2}-L^{2}$ linear estimates, where $m\in[1,2]$, we show the new influence of
+the parameter $\alpha$ on the admissible ranges of the exponent $p$.",2107.13924v1
+2021-08-17,Estimate of the attractive velocity of attractors for some dynamical systems,"In this paper, we first prove an abstract theorem on the existence of
+polynomial attractors and the concrete estimate of their attractive velocity
+for infinite-dimensional dynamical systems, then apply this theorem to a class
+of wave equations with nonlocal weak damping and anti-damping in case that the
+nonlinear term~$f$~is of subcritical growth.",2108.07410v4
+2021-08-27,Distributed Mirror Descent Algorithm with Bregman Damping for Nonsmooth Constrained Optimization,"To solve distributed optimization efficiently with various constraints and
+nonsmooth functions, we propose a distributed mirror descent algorithm with
+embedded Bregman damping, as a generalization of conventional distributed
+projection-based algorithms. In fact, our continuous-time algorithm well
+inherits good capabilities of mirror descent approaches to rapidly compute
+explicit solutions to the problems with some specific constraint structures.
+Moreover, we rigorously prove the convergence of our algorithm, along with the
+boundedness of the trajectory and the accuracy of the solution.",2108.12136v1
+2021-08-27,Non relativistic and ultra relativistic limits in 2d stochastic nonlinear damped Klein-Gordon equation,"We study the non relativistic and ultra relativistic limits in the
+two-dimensional nonlinear damped Klein-Gordon equation driven by a space-time
+white noise on the torus. In order to take the limits, it is crucial to clarify
+the parameter dependence in the estimates of solution. In this paper we present
+two methods to confirm this parameter dependence. One is the classical, simple
+energy method. Another is the method via Strichartz estimates.",2108.12183v4
+2021-09-08,The isothermal limit for the compressible Euler equations with damping,"We consider the isothermal Euler system with damping. We rigorously show the
+convergence of Barenblatt solutions towards a limit Gaussian profile in the
+isothermal limit $\gamma$ $\rightarrow$ 1, and we explicitly compute the
+propagation and the behavior of Gaussian initial data. We then show the weak L
+1 convergence of the density as well as the asymptotic behavior of its first
+and second moments. Contents 1. Introduction 1 2. Assumptions and main results
+3 3. The limit $\gamma$ $\rightarrow$ 1 of Barenblatt's solutions 6 4. Gaussian
+solutions 9 5. Evolution of certain quantities 10 6. Convergence 15 7.
+Conclusion 17 References 17",2109.03590v1
+2021-11-01,Strong solution of modified 3D-Navier-stockes equations,"In this paper we study the incompressible Navier-Stokes equations with
+logarithme damping {\alpha} log(e + |u|2)|u|2u, where we used new methods, new
+tools and Fourier analysis",2111.00859v2
+2021-11-02,Blow-up of solutions to semilinear wave equations with a time-dependent strong damping,"The paper investigates a class of a semilinear wave equation with
+time-dependent damping term ($-\frac{1}{{(1+t)}^{\beta}}\Delta u_t$) and a
+nonlinearity $|u|^p$. We will show the influence of the the parameter $\beta$
+in the blow-up results under some hypothesis on the initial data and the
+exponent $p$ by using the test function method. We also study the local
+existence in time of mild solution in the energy space $H^1(\mathbb{R}^n)\times
+L^2(\mathbb{R}^n)$.",2111.01433v1
+2021-11-02,Around plane waves solutions of the Schr{ö}dinger-Langevin equation,"We consider the logarithmic Schr{\""o}dinger equations with damping, also
+called Schr{\""o}dinger-Langevin equation. On a periodic domain, this equation
+possesses plane wave solutions that are explicit. We prove that these solutions
+are asymptotically stable in Sobolev regularity. In the case without damping,
+we prove that for almost all value of the nonlinear parameter, these solutions
+are stable in high Sobolev regularity for arbitrary long times when the
+solution is close to a plane wave. We also show and discuss numerical
+experiments illustrating our results.",2111.01487v1
+2021-11-12,GCGE: A Package for Solving Large Scale Eigenvalue Problems by Parallel Block Damping Inverse Power Method,"We propose an eigensolver and the corresponding package, GCGE, for solving
+large scale eigenvalue problems. This method is the combination of damping
+idea, subspace projection method and inverse power method with dynamic shifts.
+To reduce the dimensions of projection subspaces, a moving mechanism is
+developed when the number of desired eigenpairs is large. The numerical
+methods, implementing techniques and the structure of the package are
+presented. Plenty of numerical results are provided to demonstrate the
+efficiency, stability and scalability of the concerned eigensolver and the
+package GCGE for computing many eigenpairs of large symmetric matrices arising
+from applications.",2111.06552v1
+2021-11-25,Continuity and topological structural stability for nonautonomous random attractors,"In this work, we study continuity and topological structural stability of
+attractors for nonautonomous random differential equations obtained by small
+bounded random perturbations of autonomous semilinear problems. First, we study
+existence and permanence of unstable sets of hyperbolic solutions. Then, we use
+this to establish lower semicontinuity of nonautonomous random attractors and
+to show that the gradient structure persists under nonautonomous random
+perturbations. Finally, we apply the abstract results in a stochastic
+differential equation and in a damped wave equation with a perturbation on the
+damping.",2111.13006v1
+2021-12-20,Dense Coding Capacity in Correlated Noisy Channels with Weak Measurement,"Capacity of dense coding via correlated noisy channel is greater than that in
+uncorrelated noisy channel. It is shown that weak measurement and reversal
+measurement can make further effort to improve quantum dense coding capacity in
+correlated amplitude damping channel, but this effort is very small in
+correlated phase damping channel and correlated depolarizing channel.",2112.10346v1
+2021-12-22,Low-frequency squeezing spectrum of a laser drivenpolar quantum emitter,"It was shown by a study of the incoherent part of the low-frequency resonance
+fluorescence spectrum of the polar quantum emitter driven by semiclassical
+external laser field and damped by non-squeezed vacuum reservoir that the
+emitted fluorescence field is squeezed to some degree nevertheless. As was also
+found, a higher degree of squeezing could, in principle, be achieved by damping
+the emitter by squeezed vacuum reservoir.",2112.11809v1
+2022-01-13,Cavity optomechanics in a fiber cavity: the role of stimulated Brillouin scattering,"We study the role of stimulated Brillouin scattering in a fiber cavity by
+numerical simulations and a simple theoretical model and find good agreement
+between experiment, simulation and theory. We also investigate an
+optomechanical system based on a fiber cavity in the presence on the nonlinear
+Brillouin scattering. Using simulation and theory, we show that this hybrid
+optomechanical system increases optomechanical damping for low mechanical
+resonance frequencies in the unresolved sideband regime. Furthermore, optimal
+damping occurs for blue detuning in stark contrast to standard optomechanics.
+We investigate whether this hybrid optomechanical system is capable cooling a
+mechanical oscillator to the quantum ground state.",2201.04987v1
+2022-01-20,Vacuum and singularity formation for compressible Euler equations with time-dependent damping,"In this paper, vacuum and singularity formation are considered for
+compressible Euler equations with time-dependent damping. For $1<\gamma\leq 3$,
+by constructing some new control functions ingeniously, we obtain the lower
+bounds estimates on density for arbitrary classical solutions. Basing on these
+lower estimates, we succeed in proving the singular formation theorem for all
+$\lambda$, which was open in [1] for some cases.Moreover, the singularity
+formation of the compressible Euler equations when $\gamma=3$ is investigated,
+too.",2201.07957v1
+2022-03-19,The Equilibrium Temperature of Planets on Eccentric Orbits: Time Scales and Averages,"From estimates of the near-surface heat capacity of planets it is shown that
+the thermal time scale is larger than the orbital period in the presence of a
+global ocean that is well-mixed to a depth of 100 m, or of an atmosphere with a
+pressure of several tens of bars. As a consequence, the temperature
+fluctuations of such planets on eccentric orbits are damped. The average
+temperature should be calculated by taking the temporal mean of the irradiation
+over an orbit, which increases with $1/\sqrt{1-e^2}$. This conclusion is
+independent of the orbital distance and valid for Sun-like stars; the damping
+is even stronger for low-mass main sequence hosts.",2203.11723v1
+2022-03-31,Long-time dynamical behavior for a piezoelectric system with magnetic effect and nonlinear dampings,"This paper is concerned with the long-time dynamical behavior of a
+piezoelectric system with magnetic effect, which has nonlinear damping terms
+and external forces with a parameter. At first, we use the nonlinear semigroup
+theory to prove the well-posedness of solutions. Then, we investigate the
+properties of global attractors and the existence of exponential attractors.
+Finally, the upper semicontinuity of global attractors has been investigated.",2203.16736v1
+2022-04-04,Exponential ergodicity for damping Hamiltonian dynamics with state-dependent and non-local collisions,"In this paper, we investigate the exponential ergodicity in a
+Wasserstein-type distance for a damping Hamiltonian dynamics with
+state-dependent and non-local collisions, which indeed is a special case of
+piecewise deterministic Markov processes while is very popular in numerous
+modelling situations including stochastic algorithms. The approach adopted in
+this work is based on a combination of the refined basic coupling and the
+refined reflection coupling for non-local operators. In a certain sense, the
+main result developed in the present paper is a continuation of the counterpart
+in \cite{BW2022} on exponential ergodicity of stochastic Hamiltonian systems
+with L\'evy noises and a complement of \cite{BA} upon exponential ergodicity
+for Andersen dynamics with constant jump rate functions.",2204.01372v1
+2022-04-08,Effect of Tamm surface states on hot electron generation and Landau damping in nanostructures metal-semiconductor,"The hot electron generation in plasmonic nanoparticles is the key to
+efficient plasmonic photocatalysis. In the paper, we study theoretically for
+the first time the effect of Tamm states (TSs) at the interface
+metal-semiconductor on hot electron generation and Landau damping (LD) in metal
+nanoparticles. TSs can lead to resonant hot electron generation and to the LD
+rate enhanced by several times. The resonant hot electron generation is
+reinforced by the transition absorption due to the jump of the permittivity at
+the metal-semiconductor interface.",2204.04021v1
+2022-04-11,Certified Reduced Basis Method for the Damped Wave Equations on Networks,"In this paper we present a reduced basis method which yields
+structure-preservation and a tight a posteriori error bound for the simulation
+of the damped wave equations on networks. The error bound is based on the
+exponential decay of the energy inside the system and therefore allows for
+sharp bounds without the need of regularization parameters. The fast
+convergence of the reduced solution to the truth solution as well as the
+tightness of the error bound are verified numerically using an academic network
+as example.",2204.05010v1
+2022-04-27,Spectrum of the wave equation with Dirac damping on a non-compact star graph,"We consider the wave equation on non-compact star graphs, subject to a
+distributional damping defined through a Robin-type vertex condition with
+complex coupling. It is shown that the non-self-adjoint generator of the
+evolution problem admits an abrupt change in its spectral properties for a
+special coupling related to the number of graph edges. As an application, we
+show that the evolution problem is highly unstable for the critical couplings.
+The relationship with the Dirac equation in non-relativistic quantum mechanics
+is also mentioned.",2204.12747v1
+2022-04-27,Dependence on the thermodynamic state of self-diffusion of pseudo hard-spheres,"Self-diffusion, $D$, in a system of particles that interact with a pseudo
+hard sphere potential is analyzed. Coupling with a solvent is represented by a
+Langevin thermostat, characterized by the damping time $t_d$. The hypotheses
+that $D=D_0 \varphi$ is proposed, where $D_0$ is the small concentration
+diffusivity and $\varphi$ is a thermodynamic function that represents the
+effects of interactions as concentration is increased. Molecular dynamics
+simulations show that different values of the noise intensity modify $D_0$ but
+do not modify $\varphi$. This result is consistent with the assumption that
+$\varphi$ is a thermodynamic function, since the thermodynamic state is not
+modified by the presence of damping and noise.",2204.12969v1
+2022-04-29,Plasmon damping rates in Coulomb-coupled two-dimensional layers in a heterostructure,"The Coulomb excitations of charge density oscillation are calculated for a
+double-layer heterostructure. Specifically, we consider two-dimensional (2D)
+layers of silicene and graphene on a substrate. From the obtained surface
+response function, we calculated the plasmon dispersion relations which
+demonstrate the way in which the Coulomb coupling renormalizes the plasmon
+frequencies. Additionally, we present a novel result for the damping rates of
+the plasmons in this Coulomb coupled heterostructure and compare these results
+as the separation between layers is varied.",2205.00053v1
+2022-05-08,A regularity criterion for a 3D tropical climate model with damping,"In this paper we deal with the 3D tropical climate model with damping terms
+in the equation of the barotropic mode $u$ and in the equation of the first
+baroclinic mode $v$ of the velocity, and we establish a regularity criterion
+for this system thanks to which the local smooth solution $(u, v, \theta)$ can
+actually be extended globally in time.",2205.03841v3
+2022-06-04,Radiation backreaction in axion electrodynamics,"Energy-momentum conservation of classical axion-electrodynamics is carefully
+analyzed in the Hamiltonian formulation of the theory. The term responsible for
+the energy transfer between the electromagnetic and the axion sectors is
+identified. As a special application the axion-to-light Primakoff-process in
+the background of a static magnetic field is worked out and the radiative
+self-damping of the axion oscillations is characterized quantitatively. The
+damping time turns out comparable to the age of the Universe in the preferred
+axion mass range.",2206.02052v1
+2022-06-07,Strong attractors for weakly damped quintic wave equation in bounded domains,"In this paper, we study the longtime dynamics for the weakly damped wave
+equation with quintic non-linearity in a bounded smooth domain of
+$\mathbb{R}^3.$ Based on the Strichartz estimates for the case of bounded
+domains, we establish the existence of a strong global attractor in the phase
+space $H^2(\Omega)\cap H^1_0(\Omega)\times H^1_0(\Omega)$. Moreover, the finite
+fractal dimension of the attractor is also shown with the help of the
+quasi-stable estimation.",2206.03158v1
+2022-06-07,Long-time dynamics of the wave equation with nonlocal weak damping and sup-cubic nonlinearity in 3-D domains,"In this paper, we study the long-time dynamics for the wave equation with
+nonlocal weak damping and sup-cubic nonlinearity in a bounded smooth domain of
+$\mathbb{R}^3.$ Based on the Strichartz estimates for the case of bounded
+domains, we first prove the global well-posedness of the Shatah-Struwe
+solutions. Then we establish the existence of the global attractor for the
+Shatah-Struwe solution semigroup by the method of contractive function.
+Finally, we verify the existence of a polynomial attractor for this semigroup.",2206.03163v1
+2022-06-17,On energy-stable and high order finite element methods for the wave equation in heterogeneous media with perfectly matched layers,"This paper presents a stable finite element approximation for the acoustic
+wave equation on second-order form, with perfectly matched layers (PML) at the
+boundaries. Energy estimates are derived for varying PML damping for both the
+discrete and the continuous case. Moreover, a priori error estimates are
+derived for constant PML damping. Most of the analysis is performed in Laplace
+space. Numerical experiments in physical space validate the theoretical
+results.",2206.08507v1
+2022-06-20,Harmonic Oscillators of Mathematical Biology: Many Faces of a Predator-Prey Model,"We show that a number of models in virus dynamics, epidemiology and plant
+biology can be presented as ``damped"" versions of the Lotka-Volterra
+predator-prey model, by analogy to the damped harmonic oscillator. The analogy
+deepens with the use of Lyapunov functions, which allow us to characterize
+their dynamics and even make some estimates.",2206.09561v1
+2022-06-21,Phase-covariant mixtures of non-unital qubit maps,"We analyze convex combinations of non-unital qubit maps that are
+phase-covariant. In particular, we consider the behavior of maps that combine
+amplitude damping, inverse amplitude damping, and pure dephasing. We show that
+mixing non-unital channels can result in restoring the unitality, whereas
+mixing commutative maps can lead to non-commutativity. For the convex
+combinations of Markovian semigroups, we prove that classical uncertainties
+cannot break quantum Markovianity. Moreover, contrary to the Pauli channel
+case, the semigroup can be recovered only by mixing two other semigroups.",2206.10742v1
+2022-07-01,Stabilization results of a Lorenz piezoelectric beam with partial viscous dampings,"In this paper, we investigate the stabilization of a one-dimensional Lorenz
+piezoelectric (Stretching system) with partial viscous dampings. First, by
+using Lorenz gauge conditions, we reformulate our system to achieve the
+existence and uniqueness of the solution. Next, by using General criteria of
+Arendt-Batty, we prove the strong stability in different cases. Finally, we
+prove that it is sufficient to control the stretching of the center-line of the
+beam in x-direction to achieve the exponential stability. Numerical results are
+also presented to validate our theoretical result.",2207.00488v1
+2022-07-06,Quantum Decomposition Algorithm For Master Equations of Stochastic Processes: The Damped Spin Case,"We introduce a quantum decomposition algorithm (QDA) that decomposes the
+problem $\frac{\partial \rho}{\partial t}=\mathcal{L}\rho=\lambda \rho$ into a
+summation of eigenvalues times phase-space variables. One interesting feature
+of QDA stems from its ability to simulate damped spin systems by means of pure
+quantum harmonic oscillators adjusted with the eigenvalues of the original
+eigenvalue problem. We test the proposed algorithm in the case of undriven
+qubit with spontaneous emission and dephasing.",2207.02755v3
+2022-07-25,Geometric modelling of polycrystalline materials: Laguerre tessellations and periodic semi-discrete optimal transport,"In this paper we describe a fast algorithm for generating periodic RVEs of
+polycrystalline materials. In particular, we use the damped Newton method from
+semi-discrete optimal transport theory to generate 3D periodic Laguerre
+tessellations (or power diagrams) with cells of given volumes. Complex,
+polydisperse RVEs with up to 100,000 grains of prescribed volumes can be
+created in a few minutes on a standard laptop. The damped Newton method relies
+on the Hessian of the objective function, which we derive by extending recent
+results in semi-discrete optimal transport theory to the periodic setting.",2207.12036v1
+2022-07-27,Subsonic time-periodic solution to compressible Euler equations with damping in a bounded domain,"In this paper, we consider the one-dimensional isentropic compressible Euler
+equations with linear damping $\beta(t,x)\rho u$ in a bounded domain, which can
+be used to describe the process of compressible flows through a porous
+medium.~And the model is imposed a dissipative subsonic time-periodic boundary
+condition.~Our main results reveal that the time-periodic boundary can trigger
+a unique subsonic time-periodic smooth solution which is stable under small
+perturbations on initial data. Moreover, the time-periodic solution possesses
+higher regularity and stability provided a higher regular boundary condition.",2207.13433v1
+2022-09-10,Landau damping on the torus for the Vlasov-Poisson system with massless electrons,"This paper studies the nonlinear Landau damping on the torus $\mathbb{T}^d$
+for the Vlasov-Poisson system with massless electrons (VPME). We consider
+solutions with analytic or Gevrey ($\gamma > 1/3$) initial data, close to a
+homogeneous equilibrium satisfying a Penrose stability condition. We show that
+for such solutions, the corresponding density and force field decay
+exponentially fast as time goes to infinity. This work extends the results for
+Vlasov-Poisson on the torus to the case of ions and, more generally, to
+arbitrary analytic nonlinear couplings.",2209.04676v2
+2022-09-25,Polynomial mixing of a stochastic wave equation with dissipative damping,"We study the long time statistics of a class of semi--linear wave equations
+modeling the motions of a particle suspended in continuous media while being
+subjected to random perturbations via an additive Gaussian noise. By comparison
+with the nonlinear reaction settings, of which the solutions are known to
+possess geometric ergodicity, we find that, under the impact of nonlinear
+dissipative damping, the mixing rate is at least polynomial of any order. This
+relies on a combination of Lyapunov conditions, the contracting property of the
+Markov transition semigroup as well as the notion of $d$--small sets.",2209.12151v2
+2022-09-30,A Lyapunov approach for the exponential stability of a damped Timoshenko beam,"In this technical note, we consider the stability properties of a viscously
+damped Timoshenko beam equation with spatially varying parameters. With the
+help of the port-Hamiltonian framework, we first prove the existence of
+solutions and show, by an appropriate Lyapunov function, that the system is
+exponentially stable and has an explicit decay rate. The explicit exponential
+bound is computed for an illustrative example of which we provide some
+numerical simulations.",2209.15281v1
+2022-11-01,Well-posedness and strong attractors for a beam model with degenerate nonlocal strong damping,"This paper is devoted to initial-boundary value problem of an extensible beam
+equation with degenerate nonlocal energy damping in
+$\Omega\subset\mathbb{R}^n$: $u_{tt}-\kappa\Delta u+\Delta^2u-\gamma(\Vert
+\Delta u\Vert^2+\Vert u_t\Vert^2)^q\Delta u_t+f(u)=0$. We prove the global
+existence and uniqueness of weak solutions, which gives a positive answer to an
+open question in [24]. Moreover, we establish the existence of a strong
+attractor for the corresponding weak solution semigroup, where the ``strong""
+means that the compactness and attractiveness of the attractor are in the
+topology of a stronger space $\mathcal{H}_{\frac{1}{q}}$.",2211.00287v3
+2022-11-18,Energy decay estimates for an axially travelling string damped at one end,"We study the small vibrations of an axially travelling string with a
+dashpoint damping at one end. The string is modelled by a wave equation in a
+time-dependent interval with two endpoints moving at a constant speed $v$. For
+the undamped case, we obtain a conserved functional equivalent to the energy of
+the solution. We derive precise upper and lower estimates for the exponential
+decay of the energy with explicit constants. These estimates do not seem to be
+reported in the literature even for the non-travelling case $v=0$.",2211.10537v1
+2022-12-01,The viscous damping of three dimensional spherical gas bubble inside unbounded compressible liquid,"The present paper considers a homogeneous bubble inside an unbounded
+polytropic compressible liquid with viscosity. The system is governed by the
+Navier-Stokes equation with free boundary which is determined by the kinematic
+and dynamic boundary conditions on the bubble-liquid interface. The global
+existence of solution is proved, and the $\dot{H}^1$ asymptotic stability of
+the spherical equilibrium in terms of viscous damping together with a explicit
+decay rate is given in bare energy methods.",2212.00299v1
+2022-12-27,Stabilization of the Kawahara-Kadomtsev-Petviashvili equation with time-delayed feedback,"Results of stabilization for the higher order of the Kadomtsev-Petviashvili
+equation are presented in this manuscript. Precisely, we prove with two
+different approaches that under the presence of a damping mechanism and an
+internal delay term (anti-damping) the solutions of the
+Kawahara-Kadomtsev-Petviashvili equation are locally and globally exponentially
+stable. The main novelty is that we present the optimal constant, as well as
+the minimal time, that ensures that the energy associated with this system goes
+to zero exponentially.",2212.13552v1
+2023-03-11,Control estimates for 0th order pseudodifferential operators,"We introduce the control conditions for 0th order pseudodifferential
+operators $\mathbf{P}$ whose real parts satisfy the Morse--Smale dynamical
+condition. We obtain microlocal control estimates under the control conditions.
+As a result, we show that there are no singular profiles in the solution to the
+evolution equation $(i\partial_t-\mathbf{P})u=f$ when $\mathbf{P}$ has a
+damping term that satisfies the control condition and $f\in C^{\infty}$. This
+is motivated by the study of a microlocal model for the damped internal waves.",2303.06443v2
+2023-03-25,Existence and regularity of global attractors for a Kirchhoff wave equation with strong damping and memory,"This paper is concerned with the existence and regularity of global attractor
+$\mathcal A$ for a Kirchhoff wave equation with strong damping and memory in
+the weighted time-dependent spaces $\mathcal H$ and $\mathcal H^{1}$,
+respectively. In order to obtain the existence of $\mathcal A$, we mainly use
+the energy method in the priori estimations, and then verify the asymptotic
+compactness of the semigroup by the method of contraction function. Finally, by
+decomposing the weak solutions into two parts and some elaborate calculations,
+we prove the regularity of $\mathcal A$.",2303.14387v1
+2023-03-27,Linear Landau damping for a two-species Vlasov-Poisson system for electrons and ions,"This paper concerns the linear Landau damping for the two species
+Vlasov-Poisson system for ions and electrons near Penrose stable equilibria.
+The result is an extension of the result on the one species Vlasov-Poisson
+equation by Mouhout and Villani. Different from their work we do not describe
+the ions as a background species but as a species which is also described by a
+separate Vlasov equation. We show an exponential decay of the electric energy
+for the linearised system near Penrose stable equilibria.",2303.14981v2
+2023-03-28,Role of intersublattice exchange interaction on ultrafast longitudinal and transverse magnetization dynamics in Permalloy,"We report about element specific measurements of ultrafast demagnetization
+and magnetization precession damping in Permalloy (Py) thin films.
+Magnetization dynamics induced by optical pump at $1.5$eV is probed
+simultaneously at the $M_{2,3}$ edges of Ni and Fe with High order Harmonics
+for moderate demagnetization rates (less than $50$%). The role of the
+intersublattice exchange interaction on both longitudinal and transverse
+dynamics is analyzed with a Landau Lifshitz Bloch description of
+ferromagnetically coupled Fe and Ni sublattices. It is shown that the
+intersublattice exchange interaction governs the dissipation during
+demagnetization as well as precession damping of the magnetization vector.",2303.15837v1
+2023-03-31,Polynomial Mixing for a Weakly Damped Stochastic Nonlinear Schrödinger Equation,"This paper is devoted to proving the polynomial mixing for a weakly damped
+stochastic nonlinear Schr\""{o}dinger equation with additive noise on a 1D
+bounded domain. The noise is white in time and smooth in space. We consider
+both focusing and defocusing nonlinearities, respectively, with exponents of
+the nonlinearity $\sigma\in[0,2)$ and $\sigma\in[0,\infty)$ and prove the
+polynomial mixing which implies the uniqueness of the invariant measure by
+using a coupling method.",2303.18082v1
+2023-04-19,Inviscid damping of monotone shear flows for 2D inhomogeneous Euler equation with non-constant density in a finite channel,"We prove the nonlinear inviscid damping for a class of monotone shear flows
+with non-constant background density for the two-dimensional ideal
+inhomogeneous fluids in $\mathbb{T}\times [0,1]$ when the initial perturbation
+is in Gevrey-$\frac{1}{s}$ ($\frac{1}{2}<s<1$) class with compact support.",2304.09841v2
+2023-05-07,Nonexistence of global weak solutions to semilinear wave equations involving time-dependent structural damping terms,"We consider a semilinear wave equation involving a time-dependent structural
+damping term of the form
+$\displaystyle\frac{1}{{(1+t)}^{\beta}}(-\Delta)^{\sigma/2} u_t$. Our results
+show the influence of the parameters $\beta,\sigma$ on the nonexistence of
+global weak solutions under assumptions on the given system data.",2305.04278v1
+2023-05-15,Blow-up phenomena for a class of extensible beam equations,"In this paper, we investigate the initial boundary value problem of the
+following nonlinear extensible beam equation with nonlinear damping term $$u_{t
+t}+\Delta^2 u-M\left(\|\nabla u\|^2\right) \Delta u-\Delta
+u_t+\left|u_t\right|^{r-1} u_t=|u|^{p-1} u$$ which was considered by Yang et
+al. (Advanced Nonlinear Studies 2022; 22:436-468). We consider the problem with
+the nonlinear damping and establish the finite time blow-up of the solution for
+the initial data at arbitrary high energy level, including the estimate lower
+and upper bounds of the blowup time. The result provides some affirmative
+answer to the open problems given in (Advanced Nonlinear Studies 2022;
+22:436-468).",2305.08398v1
+2023-06-08,Vanishing of long time average p-enstrophy dissipation rate in the inviscid limit of the 2D damped Navier-Stokes equations,"In 2007, Constantin and Ramos proved a result on the vanishing long time
+average enstrophy dissipation rate in the inviscid limit of the 2D damped
+Navier-Stokes equations. In this work, we prove a generalization of this for
+the p-enstrophy, sequences of distributions of initial data and sequences of
+strongly converging right-hand sides. We simplify their approach by working
+with invariant measures on the global attractors which can be characterized via
+bounded complete solution trajectories. Then, working on the level of
+trajectories allows us to directly employ some recent results on strong
+convergence of the vorticity in the inviscid limit.",2306.05081v1
+2023-06-16,Algorithm MGB to solve highly nonlinear elliptic PDEs in $\tilde{O}(n)$ FLOPS,"We introduce Algorithm MGB (Multi Grid Barrier) for solving highly nonlinear
+convex Euler-Lagrange equations. This class of problems includes many highly
+nonlinear partial differential equations, such as $p$-Laplacians. We prove
+that, if certain regularity hypotheses are satisfied, then our algorithm
+converges in $\tilde{O}(1)$ damped Newton iterations, or $\tilde{O}(n)$ FLOPS,
+where the tilde indicates that we neglect some polylogarithmic terms. This the
+first algorithm whose running time is proven optimal in the big-$\tilde{O}$
+sense. Previous algorithms for the $p$-Laplacian required $\tilde{O}(\sqrt{n})$
+damped Newton iterations or more.",2306.10183v1
+2023-07-24,On the stability of a double porous elastic system with visco-porous dampings,"In this paper we consider a one dimensional elastic system with double
+porosity structure and with frictional damping in both porous equations. We
+introduce two stability numbers $\chi_{0}$ and $\chi_{1}$ and prove that the
+solution of the system decays exponentially provided that $\chi_{0}=0$ and
+$\chi_{1}\neq0.$ Otherwise, we prove the lack of exponential decay. Our results
+improve the results of \cite{Bazarra} and \cite{Nemsi}.",2307.12690v1
+2023-08-02,Blow-up and lifespan estimate for the generalized tricomi equation with the scale-invariant damping and time derivative nonlinearity on exterior domain,"The article is devoted to investigating the initial boundary value problem
+for the damped wave equation in the scale-invariant case with time-dependent
+speed of propagation on the exterior domain. By presenting suitable multipliers
+and applying the test-function technique, we study the blow-up and the lifespan
+of the solutions to the problem with derivative-type nonlinearity
+  $ \d u_{tt}-t^{2m}\Delta u+\frac{\mu}{t}u_t=|u_t|^p, \quad \mbox{in}\
+\Omega^{c}\times[1,\infty),$ that we associate with appropriate small initial
+data.",2308.01272v2
+2023-08-03,Gravitational Wave Heating,"It was shown in previous work that when a gravitational wave (GW) passes
+through a viscous shell of matter the magnitude of the GW will be damped and
+there are astrohysical circumstances in which the damping is almost complete.
+The energy transfer from the GWs to the fluid will increase its temperature. We
+construct a model for this process and obtain an expression for the temperature
+distribution inside the shell in terms of spherical harmonics. Further, it is
+shown that this effect is astrophysically significant: a model problem is
+constructed for which the temperature increase is of order $10^6{}^\circ$K.",2308.01615v2
+2023-08-08,Stabilization of piezoelectric beam with Coleman-Gurtin or Gurtin-Pipkin thermal law and under Lorenz gauge condition,"In this paper, we present the analysis of stability for a piezoelectric beam
+subject to a thermal law (Coleman-Gurtin or Gurtin-Pipkin thermal law) adding
+some viscous damping mechanism to the electric field in $x-$direction and
+$z-$direction, and we discuss several cases. Then, there is no need to control
+the electrical field components in $x$-direction and $z-$ direction to
+establish an exponential decay of solutions when the beam is subjected to a
+Coleman-Gurtin law, otherwise a polynomial stability is established with
+Gurtin-Pipkin thermal law in case when the electrical field components are
+damped.",2308.04231v2
+2023-08-11,Well-posedness and global attractor for wave equation with nonlinear damping and super-cubic nonlinearity,"In the paper, we study the semilinear wave equation involving the nonlinear
+damping $g(u_t) $ and nonlinearity $f(u)$. Under the wider ranges of exponents
+of $g$ and $f$, the well-posedness of the weak solution is achieved by
+establishing a priori space-time estimates. Then, the existence of the global
+attractor in the naturally phase space $H^1_0(\Omega)\times L^2(\Omega)$ is
+obtained. Moreover, we prove that the global attrator is regular, that is, the
+global attractor is a bounded subset of $(H^2(\Omega)\cap H^1_0(\Omega))\times
+H^1_0(\Omega)$.",2308.06208v1
+2023-08-16,Stability for degenerate wave equations with drift under simultaneous degenerate damping,"In this paper we study the stability of two different problems. The first one
+is a one-dimensional degenerate wave equation with degenerate damping,
+incorporating a drift term and a leading operator in non-divergence form. In
+the second problem we consider a system that couples degenerate and
+non-degenerate wave equations, connected through transmission, and subject to a
+single dissipation law at the boundary of the non-degenerate equation. In both
+scenarios, we derive exponential stability results.",2308.08645v3
+2023-09-02,Existence and nonexistence of global solutions for time-dependent damped NLS equations,"We investigate the Cauchy problem for the nonlinear Schr\""odinger equation
+with a time-dependent linear damping term. Under non standard assumptions on
+the loss dissipation, we prove the blow-up in the inter-critical regime, and
+the global existence in the energy subcritical case. Our results generalize and
+improve the ones in [9, 11, 21].",2309.00849v1
+2023-09-09,Finite-dimensionality of attractors for wave equations with degenerate nonlocal damping,"In this paper we study the fractal dimension of global attractors for a class
+of wave equations with (single-point) degenerate nonlocal damping. Both the
+equation and its linearization degenerate into linear wave equations at the
+degenerate point and the usual approaches to bound the dimension of the
+entirety of attractors do not work directly. Instead, we develop a new process
+concerning the dimension near the degenerate point individually and show the
+finite dimensionality of the attractor.",2309.04712v2
+2023-09-19,The Raman gap and collisional absorption,"One of the long-standing puzzles observed in many laser-plasma experiments is
+the gap in the Raman backscattering spectrum. This gap is characterized by the
+absence of backscattered light between some critical wavelength and twice the
+incident laser wavelength. The latter is associated with the absolute Raman
+instability from the quarter-critical density surface. Supported by
+particle-in-cell (PIC) simulations, it is suggested that the gap can result
+from the collisional damping of the backscattered light. A linear analysis of
+the competition between the Raman growth rate and the damping rate in a
+non-homogenous plasma predicts the gap's existence and width as a function of
+the system's parameters. The theory is compared with the PIC simulations and
+past experiments.",2309.10366v1
+2023-09-28,On inverse problems for a strongly damped wave equation on compact manifolds,"We consider a strongly damped wave equation on compact manifolds, both with
+and without boundaries, and formulate the corresponding inverse problems. For
+closed manifolds, we prove that the metric can be uniquely determined, up to an
+isometry, from the knowledge of the source-to-solution map. Similarly, for
+manifolds with boundaries, we prove that the metric can be uniquely determined,
+up to an isometry, from partial knowledge of the Dirichlet-to-Neumann map. The
+key point is to retrieve the spectral information of the Laplace-Beltrami
+operator, from the Laplace transform of the measurements. Further we show that
+the metric can be determined up to an isometry, using a single measurement in
+both scenarios.",2309.16182v1
+2023-10-10,Emerging Spin-Orbit Torques in Low Dimensional Dirac Materials,"We report a theoretical description of novel spin-orbit torque components
+emerging in two-dimensional Dirac materials with broken inversion symmetry. In
+contrast to usual metallic interfaces where field-like and damping-like torque
+components are competing, we find that an intrinsic damping-like torque which
+derives from all Fermi-sea electrons can be simultaneously enhanced along with
+the field-like component. Additionally, hitherto overlooked torque components
+unique to Dirac materials, emerge from the coupling between spin and pseudospin
+degrees of freedom. These torques are found to be resilient to disorder and
+could enhance the magnetic switching performance of nearby magnets.",2310.06447v1
+2023-10-22,The residual flow in well-optimized stellarators,"The gyrokinetic theory of the residual flow, in the electrostatic limit, is
+revisited, with optimized stellarators in mind. We consider general initial
+conditions for the problem, and identify cases that lead to a non-zonal
+residual electrostatic potential, i.e. one having a significant component that
+varies within a flux surface. We investigate the behavior of the ``intermediate
+residual'' in stellarators, a measure of the flow that remains after geodesic
+acoustic modes have damped away, but before the action of the slower damping
+that is caused by unconfined particle orbits. The case of a quasi-isodynamic
+stellarator is identified as having a particularly large such residual, owing
+to the small orbit width achieved by optimization.",2310.14218v1
+2023-10-26,Efficient Numerical Algorithm for Large-Scale Damped Natural Gradient Descent,"We propose a new algorithm for efficiently solving the damped Fisher matrix
+in large-scale scenarios where the number of parameters significantly exceeds
+the number of available samples. This problem is fundamental for natural
+gradient descent and stochastic reconfiguration. Our algorithm is based on
+Cholesky decomposition and is generally applicable. Benchmark results show that
+the algorithm is significantly faster than existing methods.",2310.17556v1
+2023-11-09,Exponential convergence to steady-states for trajectories of a damped dynamical system modelling adhesive strings,"We study the global well-posedness and asymptotic behavior for a semilinear
+damped wave equation with Neumann boundary conditions, modelling a
+one-dimensional linearly elastic body interacting with a rigid substrate
+through an adhesive material. The key feature of of the problem is that the
+interplay between the nonlinear force and the boundary conditions allows for a
+continuous set of equilibrium points. We prove an exponential rate of
+convergence for the solution towards a (uniquely determined) equilibrium point.",2311.05295v1
+2023-11-29,On the exponential stability of uniformly damped wave equations,"We study damped wave propagation problems phrased as abstract evolution
+equations in Hilbert spaces. Under some general assumptions, including a
+natural compatibility condition for initial values, we establish exponential
+decay estimates for all mild solutions using the language and tools of Hilbert
+complexes. This framework turns out strong enough to conduct our analysis but
+also general enough to include a number of interesting examples. Some of these
+are briefly discussed. By a slight modification of the main arguments, we also
+obtain corresponding decay results for numerical approximations obtained by
+compatible discretization strategies.",2311.18084v1
+2023-12-01,Semilinear wave inequalities with double damping and potential terms on Riemannian Manifolds,"We study a semilinear wave inequality with double damping on a complete
+noncompact Riemannian manifold. The considered problem involves a potential
+function $V$ depending on the space variable in front of the power nonlinearity
+and an inhomogeneous term $W$ depending on both time and space variables.
+Namely, we establish sufficient conditions for the nonexistence of weak
+solutions in both cases: $W\equiv 0$ and $W\not\equiv 0$. The obtained
+conditions depend on the parameters of the problem as well as the geometry of
+the manifold. Some special cases of manifolds, and of $V$ and $W$ are discussed
+in detail.",2312.00617v1
+2024-01-23,Revisit on global existence of solutions for semilinear damped wave equations in $\mathbb{R}^N$ with noncompactly supported initial data,"In this note, we study the Cauchy problem of the semilinear damped wave
+equation and our aim is the small data global existence for noncompactly
+supported initial data. For this problem, Ikehata and Tanizawa [5] introduced
+the energy method with the exponential-type weight function $e^{|x|^2/(1+t)}$,
+which is the so-called Ikehata--Todorova--Yordanov type weight. In this note,
+we suggest another weight function of the form $(1+|x|^2/(1+t))^{\lambda}$,
+which allows us to treat polynomially decaying initial data and give a simpler
+proof than the previous studies treating such initial data.",2401.12530v1
+2024-01-24,Eigenmode analysis of the damped Jaynes-Cummings model,"The generating functions for density matrix elements of the Jaynes-Cummings
+model with cavity damping are analysed in terms of their eigenmodes, which are
+characterised by a specific temporal behaviour. These eigenmodes are shown to
+be proportional to particular generalised hypergeometric functions. The
+relative weights of these eigenmodes in the generating functions are determined
+by the initial conditions of the model. These weights are found by deriving
+orthogonality relations involving adjoint modes. In an example it is shown how
+the time-dependent density matrix elements and the related factorial moments
+can be extracted from the eigenmode decompositions of the generating functions.",2401.13348v1
+2024-02-15,A comprehensive modelling and experimental approach for damped oscillations in U-tubes via Easy JavaScript Simulations,"In recent years, science simulations have become popular among educators due
+to their educational usefulness, availability, and potential for increasing the
+students' knowledge on scientific topics. In this paper, we introduce the
+implementation of a user-friendly simulation based on Easy Java/JavaScript
+Simulations (EJS) to study the problem of damped oscillations in U-tubes.
+Furthermore, we illustrate various advantages associated with the capabilities
+of EJS in terms of design and usability in order to encourage teachers to use
+it as an educational supplement to physics laboratories.",2402.09866v1
+2024-02-21,Hybrid Multi-Directional Quantum Communication Protocol,"The way a new type of state called a hybrid state, which contains more than
+one degree of freedom, is used in many practical applications of quantum
+communication tasks with lesser amount of resources. Similarly, our aim is here
+to perform multi-quantum communication tasks in a protocol to approach quantum
+information in multipurpose and multi-directional. We propose a hybrid
+multi-directional six-party scheme of implementing quantum teleportation and
+joint remote state preparation under the supervision of a controller via a
+multi-qubit entangled state as a quantum channel with 100% success probability.
+Moreover, we analytically derive the average fidelities of this hybrid scheme
+under the amplitude-damping and the phase-damping noise.",2402.14043v1
+2024-03-19,Damped energy-norm a posteriori error estimates for fully discrete approximations of the wave equation using C2-reconstructions,"We derive a posteriori error estimates for the the scalar wave equation
+discretized in space by continuous finite elements and in time by the explicit
+leapfrog scheme. Our analysis combines the idea of invoking extra
+time-regularity for the right-hand side, as previously introduced in the space
+semi-discrete setting, with a novel, piecewise quartic, globally
+twice-differentiable time-reconstruction of the fully discrete solution. Our
+main results show that the proposed estimator is reliable and efficient in a
+damped energy norm. These properties are illustrated in a series of numerical
+examples.",2403.12954v1
+2004-04-16,Transport coefficients for inelastic Maxwell mixtures,"The Boltzmann equation for inelastic Maxwell models is used to determine the
+Navier-Stokes transport coefficients of a granular binary mixture in $d$
+dimensions. The Chapman-Enskog method is applied to solve the Boltzmann
+equation for states near the (local) homogeneous cooling state. The mass, heat,
+and momentum fluxes are obtained to first order in the spatial gradients of the
+hydrodynamic fields, and the corresponding transport coefficients are
+identified. There are seven relevant transport coefficients: the mutual
+diffusion, the pressure diffusion, the thermal diffusion, the shear viscosity,
+the Dufour coefficient, the pressure energy coefficient, and the thermal
+conductivity. All these coefficients are {\em exactly} obtained in terms of the
+coefficients of restitution and the ratios of mass, concentration, and particle
+sizes. The results are compared with known transport coefficients of inelastic
+hard spheres obtained analytically in the leading Sonine approximation and by
+means of Monte Carlo simulations. The comparison shows a reasonably good
+agreement between both interaction models for not too strong dissipation,
+especially in the case of the transport coefficients associated with the mass
+flux.",0404386v2
+2006-12-12,Investigating Diffusion Coefficient Using Dynamic Light Scattering Technique,"In this work, the Z-average, effective, apparent diffusion coefficients and
+their poly-dispersity indexes were investigated for dilute poly-disperse
+homogeneous spherical particles in dispersion where the Rayleigh-Gans-Debye
+approximation is valid. The results reveal that the values of the apparent and
+effective diffusion coefficients at a scattering angle investigated are
+consistent and the difference between the effective and Z-average diffusion
+coefficients is a function of the mean particle size, size distribution and
+scattering angle. For the small particles with narrow size distributions, the
+Z-average diffusion coefficient can be got directly at any scattering angle.
+For the small particles with wide size distributions, the Z-average diffusion
+coefficient should be measured at a small scattering angle. For large
+particles, in order to obtain a good approximate value of Z-average diffusion
+coefficient, the wider the particle size distribution, the smaller the
+scattering angle that the DLS data are measured. The poly-dispersity index of
+the effective diffusion coefficient at a scattering angle investigated is
+consistent with that of the Z-average diffusion coefficient and without
+considering the influences of noises, the difference between the
+poly-dispersity indexes of the Z-average and apparent diffusion coefficients is
+determined by the mean particle size, size distribution and scattering angle
+together.",0612101v1
+2013-06-19,Conditional Stability for Single Interior Measurement,"An inverse problem to identify unknown coefficients of a partial differential
+equation by a single interior measurement is considered. The equation
+considered in this paper is a strongly elliptic second order scalar equation
+which can have complex coefficients in a bounded domain with $C^2$ boundary and
+single interior measurement means that we know a given solution of the equation
+in this domain. The equation includes some model equations arising from
+acoustics, viscoelasticity and hydrology. We assume that the coefficients are
+piecewise analytic. Our major result is the local H\""older stability estimate
+for identifying the unknown coefficients. If the unknown coefficients is a
+complex coefficient in the principal part of the equation, we assumed a
+condition which we named admissibility assumption for the real part and
+imaginary part of the difference of the two complex coefficients. This
+admissibility assumption is automatically satisfied if the complex coefficients
+are real valued. For identifying either the real coefficient in the principal
+part or the coefficient of the 0-th order of the equation, the major result
+implies the global uniqueness for the identification.",1306.4433v2
+2016-04-04,Combinatorics on several families of Kronecker coefficients related to plane partitions,"We present a study of three families of Kronecker coefficients, which we
+describe in terms of reduced Kronecker coefficients. This study is grounded on
+the generating function of the coefficients, proved by a bijection between two
+combinatorial objects. This study includes the connection between plane
+partitions and these three families of reduced Kronecker coefficients,
+providing us their combinatorial interpretation. As an application, we verify
+that the saturation hypothesis holds for our three families of reduced
+Kronecker coefficients. The study also includes other interpretation in terms
+of the quasipolynomials that govern these families. We specify the degree and
+the period of these quasipolynomials. Finally, the direct relation between
+Kronecker coefficients and reduced Kronecker coefficients allows us to give
+some observations about the rate of growth of the Kronecker coefficients
+associated to the reduced Kronecker coefficients of the study.",1604.00803v1
+2022-06-29,Complexity of representations of coefficients of power series in classical statistical mechanics. Their classification and complexity criteria,"It is declared that the aim of simplifying representations of coefficients of
+power series of classical statistical mechanics is to simplify a process of
+obtaining estimates of the coefficients using their simplified representations.
+The aim of the article is: to formulate criteria for the complexity (from the
+above point of view) of these representations and to demonstrate their
+application by examples of comparing Ree-Hoover representations of virial
+coefficients and such representations of power series coefficients that are
+based on the conception of the frame classification of labeled graphs.
+  To solve these problems, mathematical notions were introduced (such as a base
+product, a base integral, a base linear combination of integrals, a base linear
+combination of integrals with coefficients of negligible complexity, a base set
+of base linear combinations of integrals with coefficients of negligible
+complexity); and a classification of representations of coefficients of power
+series of classical statistical mechanics is proposed. In this classification
+the class of base linear combinations of integrals with coefficients of
+negligible complexity is the most important class. It includes the most
+well-known representations of the coefficients of power series of classical
+statistical mechanics.
+  Three criteria are formulated to estimate the comparative complexity of base
+linear combinations of integrals with coefficients of negligible complexity and
+their extensions to the totality of base sets of base linear combinations of
+integrals with coefficients of negligible complexity are constructed. The
+application of all the constructed criteria is demonstrated by examples of
+comparing with each other of the above power series coefficients
+representations. The obtained results are presented in the tables and
+commented.",2207.07583v1
+2023-09-15,Doeblin Coefficients and Related Measures,"Doeblin coefficients are a classical tool for analyzing the ergodicity and
+exponential convergence rates of Markov chains. Propelled by recent works on
+contraction coefficients of strong data processing inequalities, we investigate
+whether Doeblin coefficients also exhibit some of the notable properties of
+canonical contraction coefficients. In this paper, we present several new
+structural and geometric properties of Doeblin coefficients. Specifically, we
+show that Doeblin coefficients form a multi-way divergence, exhibit
+tensorization, and possess an extremal trace characterization. We then show
+that they also have extremal coupling and simultaneously maximal coupling
+characterizations. By leveraging these characterizations, we demonstrate that
+Doeblin coefficients act as a nice generalization of the well-known total
+variation (TV) distance to a multi-way divergence, enabling us to measure the
+""distance"" between multiple distributions rather than just two. We then prove
+that Doeblin coefficients exhibit contraction properties over Bayesian networks
+similar to other canonical contraction coefficients. We additionally derive
+some other results and discuss an application of Doeblin coefficients to
+distribution fusion. Finally, in a complementary vein, we introduce and discuss
+three new quantities: max-Doeblin coefficient, max-DeGroot distance, and
+min-DeGroot distance. The max-Doeblin coefficient shares a connection with the
+concept of maximal leakage in information security; we explore its properties
+and provide a coupling characterization. On the other hand, the max-DeGroot and
+min-DeGroot measures extend the concept of DeGroot distance to multiple
+distributions.",2309.08475v1
+1995-02-09,A linear thermohaline oscillator driven by stochastic atmospheric forcing,"The interdecadal variability of a stochastically forced four-box model of the
+oceanic meridional thermohaline circulation (THC) is described and compared to
+the THC variability in the coupled ocean-atmosphere GCM of Delworth, Manabe,
+and Stouffer (1993). The box model is placed in a linearly stable thermally
+dominant mean state under mixed boundary conditions. A linear stability
+analysis of this state reveals one damped oscillatory THC mode in addition to
+purely damped modes. The variability of the model under a moderate amount of
+stochastic forcing, meant to emulate the random variability of the atmosphere
+affecting the coupled model's interdecadal THC variability, is studied. A
+linear interpretation, in which the damped oscillatory mode is of primary
+importance, is sufficient for understanding the mechanism accounting for the
+stochastically forced variability. Direct comparison of the variability in the
+box model and coupled GCM reveals common qualitative aspects. Such a comparison
+supports, although does not verify, the hypothesis that the coupled model's THC
+variability can be interpreted as the result of atmospheric weather exciting a
+linear damped oscillatory THC mode.",9502002v2
+1993-09-30,The metal systems in Q0000--2619 at high resolution,"We have obtained high, 11 and 14 \kms, and medium, 40 and 53 \kms, resolution
+spectra of the $z_{em} = 4.11$ quasar Q0000--2619 covering the range 4400 \AA\
+to 9265 \AA . We identify nine metal absorption systems, of which four were
+previously known. A fifth previously suggested system at $z_{abs} \approx
+3.409$ (Turnshek et al~ 1991) is ruled out by our data. Two of the eight
+systems for which the \lya~ line is in the observable range have a damped \lya~
+line. Six of the nine systems show evidence for complex sub--component
+structure. At our resolution and S/N we identify a total of 21 sub--components
+in the nine systems. Five of the nine systems (11 of the 21 components) fall
+within the $\pm 5000$ \kms~ range of the emission redshift, and are hence
+classified as \zae~ absorbers. For the two damped systems we find metal
+abundances of $\leq 1$% and $\leq 8$% of solar values at redshifts of 3.0541
+and 3.3901 respectively. These upper limits are consistent with what would be
+expected from previous determinations at lower redshifts, and our data are
+hence compatible with earlier conclusions that no evidence is yet found for
+chemical evolution of intervening damped and Lyman limit absorbers. For the
+\zae~ systems we found indications of metallicities comparable to, and even in
+excess of solar values. These much higher values compared to the damped
+systems, are in favour of the intrinsic hypothesis for these systems.",9309053v1
+1994-12-27,The z=0.8596 Damped Lyman Alpha Absorbing Galaxy Toward PKS 0454+039,"We present {\it Hubble Space Telescope} and ground--based data on the
+$z_{abs}=0.8596$ metal line absorption system along the line of sight to PKS
+0454+0356. The system is a moderate redshift damped Lyman alpha system, with
+${\rm N(HI)}=(5.7\pm0.3)\times10^{20}$~cm$^{-2}$ as measured from the {\it
+Faint Object Spectrograph} spectrum. We also present ground--based images which
+we use to identify the galaxy which most probably gives rise to the damped
+system; the most likely candidate is relatively underluminous by QSO absorber
+standards ($M_B \sim -19.0$ for $q_0=0.5$ and $H_0=50$ \kms Mpc$^{-1}$), and
+lies $\sim 8.5h^{-1}$ kpc in projection from the QSO sightline. Ground--based
+measurements of Zn~II, Cr~II, and Fe~II absorption lines from this system allow
+us to infer abundances of [Zn/H]=$-1.1$, [Cr/H]=$-1.2$, and [Fe/H]=$-1.2$,
+indicating overall metallicity similar to damped systems at $z >2$, and that
+the depletion of Cr and Fe onto dust grains may be even {\it less} important
+than in many of the high redshift systems of comparable metallicity. Limits
+previously placed on the 21-cm optical depth in the $z=0.8596$ system, together
+with our new N(H~I) measurement, suggest a very high spin temperature for the
+H~I, $T_S >> 580$ K.",9412093v2
+1995-05-17,GRAVITATIONAL LENSING OF QUASARS BY THEIR DAMPED LYMAN-ALPHA ABSORBERS,"Damped Lyman-alpha absorbers are believed to be associated with galactic
+disks. We show that gravitational lensing can therefore affect the statistics
+of these systems. First, the magnification bias due to lensing raises faint
+QSOs above a given magnitude threshold and thereby enhances the probability for
+observing damped absorption systems. Second, the bending of light rays from the
+source effectively limits the minimum impact parameter of the line-of-sight
+relative to the center of the absorber, thus providing an upper cut-off to the
+observed neutral hydrogen (HI) column density. The combination of these effects
+yields a pronounced peak in the observed abundance of absorbers with high
+column densities (>2*10^{21} cm^{-2}) and low redshifts (z<1). The inferred
+value of the cosmological density parameter of neutral hydrogen, Omega_{HI},
+increases with increasing redshift and luminosity of the sources even if the
+true HI density remains constant. This trend resembles the observed evolution
+of Omega_{HI}(z). Damped Lyman-alpha absorbers with column densities >10^{21}
+cm^{-2} and redshifts 0.5<z<1 are reliable flags for lensed QSOs with a close
+pair of images separated by 0.3 arcsec. Detection of these gravitational
+lensing signatures with the Hubble Space Telescope can be used to constrain the
+depth of the absorber potential-wells and the cosmological constant.",9505078v1
+1996-08-22,APM z>4 QSO Survey: Distribution and Evolution of High Column Density HI Absorbers,"Eleven candidate damped Lya absorption systems were identified in 27 spectra
+of the quasars from the APM z>4 survey covering the redshift range
+2.8<z(abs)<4.4 (8 with z(abs)>3.5). High resolution echelle spectra (0.8A FWHM)
+have been obtained for three quasars, including 2 of the highest redshift
+objects in the survey. Two damped systems have confirmed HI column densities of
+N(HI) >= 10^20.3 atoms cm^-2, with a third falling just below this threshold.
+We have discovered the highest redshift damped Lya absorber known at z=4.383 in
+QSO BR1202-0725. The APM QSOs provide a substantial increase in the redshift
+path available for damped surveys for z>3. We combine this high redshift sample
+with other quasar samples covering the redshift range 0.008 < z < 4.7 to study
+the redshift evolution and the column density distribution function for
+absorbers with log N(HI)>=17.2. In the HI column density distribution
+f(N)=kN^-beta we find evidence for breaks in the power law, flattening for
+17.2< log N(HI)<21 and steepening for log N(HI)>21.2. The column density
+distribution function for the data with log N(HI)>=20.3 is better fit with the
+form f(N)=(f*/N*)(N/N*)^-beta exp(-N/N*). Significant redshift evolution in the
+number density per unit redshift is evident in the higher column density
+systems with an apparent decline in N(z) for z>3.5.",9608146v1
+1997-05-16,Testing Cosmological Models Against the Abundance of Damped Lyman-Alpha Absorbers,"We calculate the number of damped Lyman-alpha absorbers expected in various
+popular cosmological models as a function of redshift and compare our
+predictions with observed abundances. The Press-Schechter formalism is used to
+obtain the distribution of halos with circular velocity in different
+cosmologies, and we calibrate the relation between circular velocity and
+absorption cross-section using detailed gas dynamical simulations of a
+``standard'' cold dark matter (CDM) model. Because of this calibration, our
+approach makes more realistic assumptions about the absorption properties of
+collapsed objects than previous, analytic calculations of the damped
+Lyman-alpha abundance. CDM models with Omega_0=1, H_0=50, baryon density
+Omega_b=0.05, and scale-invariant primeval fluctuations reproduce the observed
+incidence and redshift evolution of damped Lyman-alpha absorption to within
+observational uncertainty, for both COBE normalization (sigma_8=1.2) and a
+lower normalization (sigma_8=0.7) that better matches the observed cluster
+abundance at z=0. A tilted (n=0.8, sigma_8=0.7) CDM model tends to underproduce
+absorption, especially at z=4. With COBE normalization, a CDM model with
+Omega_0=0.4, Omega_{Lambda}=0.6 gives an acceptable fit to the observed
+absorption; an open CDM model is marginally acceptable if Omega_0 is at least
+0.4 and strongly inconsistent with the z=4 data if Omega_0=0.3. Mixed dark
+matter models tend not to produce sufficient absorption, being roughly
+comparable to tilted CDM models if Omega_{nu} = 0.2 and failing drastically if
+Omega_{nu} = 0.3.",9705118v1
+1997-05-28,Zinc and Chromium Abundances in a Third Damped Lyman alpha System at Intermediate Redshift,"We have determined the metallicity of the $z_{abs} = 1.0093$ damped Lyman
+alpha system in the bright QSO EX 0302-223; this is only the third such
+measurement at redshifts $z \simlt 1$. Unlike the previous two cases, we find
+that the abundance of Zn is only a factor of $\sim 2$ lower than in the
+Galactic interstellar medium today and is entirely compatible with the typical
+metallicity of stars in the Milky Way disk at a look-back time of 9.5 Gyrs.
+Although the galaxy responsible for producing the absorption system has yet to
+be positively identified, our observations show that galaxies on a chemical
+evolution path similar to that of the Milky Way do contribute to the damped
+Lyman alpha population at intermediate redshifts. Cr is 2.5 times less abundant
+than Zn, presumably because of depletion onto dust; however, the degree of
+depletion is less severe than in diffuse interstellar clouds in the disk of our
+Galaxy and in the Magellanic Clouds. Evidently, the interstellar environment in
+damped Lyman alpha galaxies is less conducive to the formation and survival of
+dust grains (and molecular hydrogen), but the physical processes at the root of
+this effect have yet to be clarified.",9705222v1
+1998-11-18,The Closest Damped Lyman Alpha System,"A difficulty of studying damped Lyman alpha systems is that they are distant,
+so one knows little about the interstellar medium of the galaxy. Here we report
+upon a damped Lyman alpha system in the nearby galaxy NGC 4203, which is so
+close (v_helio = 1117 km/s) and bright (B_o = 11.62) that its HI disk has been
+mapped. The absorption lines are detected against Ton 1480, which lies only
+1.9' (12 h_50 kpc) from the center of NGC 4203. Observations were obtained with
+the Faint Object Spectrograph on HST (G270H grating) over the 2222-3277
+Angstrom region with 200 km/s resolution. Low ionization lines of Fe, Mn, and
+Mg were detected, leading to metallicities of -2.29, < -0.68, and > -2.4, which
+are typical of other damped Lyman alpha systems, but well below the stellar
+metallicity of this type of galaxy. Most notably, the velocity of the lines is
+1160 +- 10 km/s, which is identical to the HI rotational velocity of 1170 km/s
+at that location in NGC 4203, supporting the view that these absorption line
+systems can be associated with the rotating disks of galaxies. In addition, the
+line widths of the Mg lines give an upper limit to the velocity dispersion of
+167 km/s, to the 99% confidence level.",9811274v1
+1999-07-29,Ionized Gas in Damped Lyman-alpha Systems and Its Effects on Elemental Abundance Studies,"Recent high-resolution observations of metal absorption lines in
+high-redshift damped Ly-alpha systems have shown that Al III, a tracer of
+moderately-ionized gas, very often has a velocity structure indistinguishable
+from that of low-ionization gas. Regions of ionized and neutral hydrogen in
+these systems are likely cospatial. The higher-ionization Si IV and C IV
+absorption shows a much weaker or non-existent correlation with the low
+ionization material, implying that the regions traced by Al III are
+photoionized by a soft (stellar) spectrum, by a hard (power law) spectrum with
+a very low ionization parameter, or a combination of both. We discuss the
+ionization of the damped Ly-alpha systems and use photoionization equilibrium
+models to make quantitative estimates of its effects on abundance studies in
+these systems. We show that ionization effects may be large enough to account
+for the observed dispersion in absolute metal abundances in damped Ly-alpha
+systems, causing systematically higher abundances in lower column density
+systems. The observed Si^+/Fe^+ and Zn^+/Cr^+ ratios may systematically
+overestimate the intrinsic Si/Fe and Zn/Cr ratios, respectively, if ionized gas
+is present in these systems, thereby mimicking the effects of alpha-element
+enrichment or dust depletion.",9907428v1
+1999-11-09,Detection of Warm and Cold Phases of the Neutral ISM in a Damped Ly-alpha Absorber,"We present a detailed study of the HI 21cm absorption system at z=0.0912
+towards the radio quasar B0738+313. The uncommonly narrow main absorption line
+and weak secondary line are resolved for the first time. In addition we find it
+necessary to add a third, broader shallow component to obtain a good fit to the
+spectrum. Although the harmonic mean spin temperature calculated by comparison
+of the 21cm lines to the damped Ly-alpha line is T_s = 775 K, the thermal
+kinetic temperatures of the two narrow components, calculated from their
+widths, are much lower: T_k \leq 297 and \leq 103 K respectively. This is the
+first case of a redshifted absorption system for which T_k is measured to be
+less than T_s. We discuss this result in the context of a two phase gas model,
+in which the damped Ly-alpha gas is sensitive to a significant neutral column
+density of warm phase gas as well as the cold phase gas of the narrow 21cm
+lines. The third component is interpreted as representing the warm phase gas
+with with T_k \leq 5050 K. The combined column density of the three 21cm
+components is approximately equal to that derived from fits to the damped
+Ly-alpha line.",9911142v1
+2000-06-01,Crust-core coupling and r-mode damping in neutron stars: a toy model,"R-modes in neutron stars with crusts are damped by viscous friction at the
+crust-core boundary. The magnitude of this damping, evaluated by Bildsten and
+Ushomirsky (BU) under the assumption of a perfectly rigid crust, sets the
+maximum spin frequency for a neutron star spun up by accretion in a Low-Mass
+X-ray binary (LMXB). In this paper we explore the mechanical coupling between
+the core r-modes and the elastic crust, using a toy model of a constant density
+neutron star with a constant shear modulus crust. We find that, at spin
+frequencies in excess of ~50 Hz, the r-modes strongly penetrate the crust. This
+reduces the relative motion (slippage) between the crust and the core compared
+to the rigid crust limit. We therefore revise down, by as much as a factor of
+10^2-10^3, the damping rate computed by BU, significantly reducing the maximal
+possible spin frequency of neutron star with a solid crust. The dependence of
+the crust-core slippage on the spin frequency is complicated, and is very
+sensitive to the physical thickness of the crust. If the crust is sufficiently
+thick, the curve of the critical spin frequency for the onset of the r-mode
+instability becomes multi-valued for some temperatures; this is related to the
+avoided crossings between the r-mode and the higher-order torsional modes in
+the crust. The critical frequencies are comparable to the observed spins of
+neutron stars in LMXBs and millisecond pulsars.",0006028v1
+2001-03-23,First Investigation of the Clustering Environment of Damped Lyman Alpha Absorbers at z=4,"We report the first observations of the clustering environment of damped
+Lyman alpha absorption systems at z=4. Color selection and photometric
+redshifts were used to select 44 candidate Lyman-break galaxies brighter than
+I_AB=25.5 from deep BRI images of the 35 sq. arcmin field containing the quasar
+BR 0951-04. Multislit spectroscopy of 35 candidate galaxies was performed and 8
+of these candidates have been confirmed as z>3.5 Lyman-break galaxies. With
+only BRI photometry, the photometric redshifts are quite accurate for the
+spectroscopically confirmed galaxies but have a high rate of misclassification
+due to color degeneracies between Lyman-break galaxies and low-redshift
+ellipticals. Both of the z>3.5 galaxies found within 15'' of the quasar
+line-of-sight appear to be causing absorption systems in the quasar spectrum.
+We use a battery of statistical tests to look for clustering in the redshift
+histogram of the z>3.5 galaxies but do not find measurable clustering of these
+Lyman-break galaxies with the damped Lyman alpha absorbers. With a larger
+sample of galaxies, our method should determine the cross-correlation between
+these objects, which probes the bias and hence the mass of the damped Lyman
+alpha absorbers.",0103387v2
+2002-11-11,Damped Lyman alpha systems and galaxy formation models - II. High ions and Lyman limit systems,"We investigate a model for the high-ionization state gas associated with
+observed damped Lyman-alpha systems, based on a semi-analytic model of galaxy
+formation set within the paradigm of hierarchical structure formation. In our
+model, the hot gas in halos and sub-halos gives rise to CIV absorption, while
+the low-ionization state gas is associated with the cold gas in galaxies. The
+model matches the distribution of CIV column densities and leads naturally to
+kinematic properties that are in good agreement with the data.
+  We examine the contribution of both hot and cold gas to sub-damped systems
+and suggest that the properties of these systems can be used as an important
+test of the model. We expect that sub-DLA systems will generally be composed of
+a single gas disk and thus predict that they should have markedly different
+kinematics than the damped systems.
+  Finally, we find that hot halo gas produces less than one third of Lyman
+limit systems at redshift three. We model the contribution of mini-halos (halos
+with virial velocities < 35 km/s) to Lyman limit systems and find that they may
+contain as much gas as is observed in these systems. However, if we adopt
+realistic models of the gas density distribution we find that these systems are
+not a significant source of Lyman limit absorption. Instead we suggest that
+uncollapsed gas outside of virialized halos is responsible for most of the
+Lyman limit systems at high redshift.",0211231v1
+2003-05-16,The Age-Metallicity Relation of the Universe in Neutral Gas: The First 100 Damped Lya Systems,"We present accurate metallicity measurements for 121 damped Lya systems at
+0.5<z<5 including ~50 new measurements from our recently published Echellette
+Spectrograph and Imager surveys. This dataset is analysed to determine the
+age-metallicity relation of neutral gas in the universe. Contrary to previous
+datasets this sample shows statistically significant evolution in the mean
+metallicity. The best linear fit rate to metallicity vs. redshift is -0.26 +/-
+0.07 dex corresponding to approximately a factor of 2 every Gyr at z=3. The DLA
+continue to maintain a floor in metallicity of ~1/700 solar independent of
+observational effects. This metallicity threshold limits the prevalence of
+primordial gas in high redshift galaxies and stresses the correspondence
+between damped systems and star formation (i.e. galaxy formation). This floor
+is significantly offset from the metallicity of the Lya forest and therefore we
+consider it to be more related to active star formation within these galaxies
+than scenarios of enrichment in the very early universe. Finally, we comment on
+an apparent 'missing metals problem': the mean metallicity of the damped
+systems is ~10x lower than the value expected from their observed star
+formation history. This problem is evident in current theoretical treatments of
+chemical evolution and galaxy formation; it may indicate a serious flaw in our
+understanding of the interplay between star formation and metal production.",0305314v1
+2003-09-24,WIMP matter power spectra and small scale power generation,"Dark Matter (DM) is generally assumed to be massive, cold and collisionless
+from the structure formation point of view. A more correct statement however is
+that DM indeed experiences collisional damping, but on a scale which is
+supposed to be too small to be relevant for structure formation. The aim of
+this paper is to present a Cold (although ``collisional'') Dark Matter particle
+whose matter power spectrum is damped and see whether it is distinguishable
+from standard candidates. To achieve this purpose, we calculate the collisional
+damping and free-streaming scales of neutralinos and non conventional
+candidates (say light particles heavier than ~1 MeV but lighter than O(10)
+GeV). The latter can be considered as Cold Dark Matter (CDM) particles in the
+sense that they become non relativistic before their thermal decoupling epoch.
+Unlike neutralinos, however, their linear matter power spectrum can be damped
+on scales of ~ 10^3 Msol due to their interactions. Since these scales are of
+cosmological interest for structure formation, we perform a series of numerical
+simulations to obtain the corresponding non linear matter power spectra
+P(k)_{nl} at the present epoch. We show that because of small scale
+regeneration, they all resemble each other at low redshifts, i.e. become very
+similar to a typical CDM matter power spectrum on all but the smallest scales.
+Therefore, even if lensing measurements at redshift below unity were to yield a
+P(k)_{nl} consistent with CDM models, this would not constitute a sufficiently
+robust evidence in favour of the neutralino to rule out alternative DM
+candidates.",0309652v1
+2004-03-16,The SDSS Damped Lya Survey: Data Release 1,"We present the results from an automated search for damped Lya (DLA) systems
+in the quasar spectra of Data Release 1 from the Sloan Digital Sky Survey
+(SDSS-DR1). At z~2.5, this homogeneous dataset has greater statistical
+significance than the previous two decades of research. We derive a statistical
+sample of 71 damped Lya systems (>50 previously unpublished) at z>2.1 and
+measure HI column densities directly from the SDSS spectra. The number of DLA
+systems per unit redshift is consistent with previous measurements and we
+expect our survey has >95% completeness. We examine the cosmological baryonic
+mass density of neutral gas Omega_g inferred from the damped Lya systems from
+the SDSS-DR1 survey and a combined sample drawn from the literature. Contrary
+to previous results, the Omega_g values do not require a significant correction
+from Lyman limit systems at any redshift. We also find that the Omega_g values
+for the SDSS-DR1 sample do not decline at high redshift and the combined sample
+shows a (statistically insignificant) decrease only at z>4. Future data
+releases from SDSS will provide the definitive survey of DLA systems at z~2.5
+and will significantly reduce the uncertainty in Omega_g at higher redshift.",0403391v2
+2006-06-28,Neutral gas density in Damped Lyman Alpha systems,"We estimate the intrinsic neutral gas density in Damped Lyman Alpha systems
+($\Omega_{HI}^{(DLA)}$) in the redshift range $ 2.2 \lesssim z \lesssim 5$ from
+the DLA SDSS DR_3 sample of optically selected quasars. We take into account
+self-consistently the obscuration on background quasars due to the dust present
+in Damped Lyman Alpha systems. We model the column density and redshift
+distribution of these systems by using both a non-parametric and a parametric
+approach. Under conservative assumptions on the dust content of Damped Lyman
+$\alpha$ systems, we show that selection effects lead to underestimating the
+intrinsic neutral gas density by at least $15\%$ with respect to the observed
+neutral gas density. Over the redshift range $[2.2;5.5]$ we find
+$\Omega_{HI}^{(DLA)}=0.97^{+0.08+0.28}_{-0.06-0.15} \cdot 10^{-3}$, where the
+first set of error bars gives the $1\sigma$ random errors and the second set
+gives the modeling uncertainty dependent on the fraction of metals in dust -
+from 0\% to 50\%. This value compares with
+$\Omega_{HI}^{(DLA)}=0.82^{+0.05}_{-0.05}$ ($1\sigma$ error bars), which is
+obtained when no correction for dust is introduced. In the model with half of
+the metals mass in dust we cannot constraint $\Omega_{HI}^{(DLA)}$ at a
+confidence level higher than $90\%$. In this case there is indeed a probability
+of about $10\%$ that the intrinsic column density distribution of DLA systems
+is a power law $f(N_{HI}) \propto 1/N_{HI}^{~1.95}$. In contrast, with $25 \%$
+of the metals in dust - the most realistic estimate - a power law is ruled out
+at $99.5\%$ of confidence level.",0606693v1
+2006-09-06,Sun-as-a-star observations: evidence for degree dependence of changes in damping of low-l p modes along the solar cycle,"We use 9.5-yr of BiSON Sun-as-a-star data to search for dependence of
+solar-cycle parameter changes on the angular degree, l, of the data. The nature
+of the Sun-as-a-star observations is such that for changes measured at fixed
+frequency, or for changes averaged across the same range in frequency, any l
+dependence present carries information on the latitudinal distribution of the
+agent (i.e., the activity) responsible for those changes. We split the 9.5-yr
+timeseries into contiguous 108-d pieces, and determine mean changes in the
+damping of, power in, and energy supplied to the modes through the solar cycle.
+We also apply a careful correction to account for the deleterious effects of
+the ground-based BiSON window function on the results. From our full analysis
+we obtain a marginally significant result for the damping parameter, where the
+mean change is found to be weakest at l=0. The other parameters show hints of
+some dependence in l. Our main conclusion is that the mean fractional
+solar-cycle change in the l=0 damping rates is approximately 50 % smaller than
+was previously assumed. It had been common practice to use an average over all
+low-l modes; our downward revision of the radial-mode value has implications
+for comparisons with models of the global solar cycle changes, which are
+usually based on a spherically symmetric geometry.",0609156v2
+1997-08-12,Coherence in the Quasi-Particle 'Scattering' by the Vortex Lattice in Pure Type-II Superconductors,"The effect of quasi-particle (QP) 'scattering' by the vortex lattice on the
+de-Haas van-Alphen oscillations in a pure type-II superconductor is
+investigated within mean field,asymptotic perturbation theory. Using a 2D
+electron gas model it is shown that, due to a strict phase coherence in the
+many-particle correlation functions, the 'scattering' effect in the asymptotic
+limit ($\sqrt{E_F/\hbar\omega_c}\gg 1$) is much weaker than what is predicted
+by the random vortex lattice model proposed by Maki and Stephen, which destroys
+this coherence . The coherent many particle configuration is a collinear array
+of many particle coordinates, localized within a spatial region with size of
+the order of the magnetic length. The amplitude of the magnetization
+oscillations is sharply damped just below $% H_{c2}$ because of strong
+$180^{\circ}$ out of phase magnetic oscillations in the superconducting
+condensation energy ,which tend to cancel the normal electron oscillations.
+Within the ideal 2D model used it is found, however, that because of the
+relative smallness of the quartic and higher order terms in the expansion, the
+oscillations amplitude at lower fields does not really damp to zero, but only
+reverses sign and remains virtually undamped well below $H_{c2}$. This
+conclusion may be changed if disorder in the vortex lattice, or vortex lines
+motion will be taken into account. The reduced QP 'scattering' effect may be
+responsible for the apparent crossover from a strong damping of the dHvA
+oscillations just below $H_{c2}$ to a weaker damping at lower fields observed
+experimentally in several 3D superconductors.",9708088v1
+1999-08-27,Electron Correlations in an Electron Bilayer at Finite Temperature: Landau Damping of the Acoustic Plasmon,"We report angle-resolved Raman scattering observations of the temperature
+dependent Landau damping of the acoustic plasmon in an electron bilayer system
+realised in a GaAs double quantum well structure. Corresponding calculations of
+the charge-density excitation spectrum of the electron bilayer using forms of
+the random phase approximation (RPA), and the static local field formalism of
+Singwi, Tosi, Land and Sj\""{o}lander (STLS) extended to incorporate non-zero
+electron temperature $T_{\rm e}$ and phenomenological damping, are also
+presented. The STLS calculations include details of the temperature dependence
+of the intra- and inter-layer local field factors and pair-correlation
+functions. Good agreement between experiment and the various theories is
+obtained for the acoustic plasmon energy and damping for $T_{\rm e} \lesssim
+T_{\rm F}/2$, the Fermi temperature. However, contrary to current expectations,
+all of the calculations show significant departures from our experimental data
+for $T_{\rm e} \gtrsim T_{\rm F}/2$. From this, we go on to demonstrate
+unambiguously that real local field factors fail to provide a physically
+accurate description of exchange correlation behaviour in low dimensional
+electron gases. Our results suggest instead that one must resort to a
+{\em{dynamical}} local field theory, characterised by a {\em{complex}} field
+factor to provide a more accurate description.",9908408v1
+2000-10-02,"Comment on ""Magnetic Breakdown at High Fields: Semiclassical and Quantum Treatments""","We comment on the study of the spin-damping factor on the de Haas-van Alphen
+(dHvA) discussed by Han et al. (Phys. Rev. Lett. 85, 1500 (2000)).",0010018v1
+2002-03-11,Shubnikov - de Haas effect in the quantum vortex liquid state of the organic superconductor $κ$-(BEDT-TTF)$_{2}$Cu(NCS)$_{2}$,"We report the Shubnikov-de Haas (SdH) oscillations observed in the vortex
+liquid state of the quasi two dimensional organic superconductor
+$\kappa$-(BEDT-TTF)$_{2}$Cu(NCS)$_{2}$. The SdH oscillations can be observed
+down to about 5 T at 0.5 K, where the flux flow resistivity becomes as small as
+about 30 % of the normal state value. Below the upper critical field $H_{\rm
+c2}$ of about 7 T, the additional damping of the SdH oscillation amplitude
+appears, as well as that of the de Haas-van Alphen (dHvA) oscillations, with
+respect to the normal state one which is described with the standard
+Lifshitz-Kosevich formula. The magnitude of the additional damping near $H_{\rm
+c2}$ is the same with that observed in the dHvA oscillations and well explained
+by the theoretical predictions in consideration of fluctuations in the thermal
+vortex liquid state. In the quantum fluctuation region at lower temperature,
+however, only SdH effect shows the stronger damping than that of the dHvA
+oscillations. The different magnetic field dependence of the additional damping
+of the oscillation amplitude between the SdH and dHvA effects is discussed in
+connection with the effect of the transport current on the short-range order of
+vortices in the quantum vortex slush state reported at the same temperature and
+magnetic field region.",0203228v2
+2003-03-13,Vibrational sidebands and dissipative tunneling in molecular transistors,"Transport through molecular devices with strong coupling to a single
+vibrational mode is considered in the case where the vibration is damped by
+coupling to the environment. We focus on the weak tunneling limit, for which a
+rate equation approach is valid. The role of the environment can be
+characterized by a frictional damping term $\mysig(\omega)$ and corresponding
+frequency shift. We consider a molecule that is attached to a substrate,
+leading to frequency-dependent frictional damping of the single oscillator mode
+of the molecule, and compare it to a reference model with frequency-independent
+damping featuring a constant quality factor $Q$. For large values of $Q$, the
+transport is governed by tunneling between displaced oscillator states giving
+rise to the well-known series of the Frank-Condon steps, while at small $Q$,
+there is a crossover to the classical regime with an energy gap given by the
+classical displacement energy. Using realistic values for the elastic
+properties of the substrate and the size of the molecule, we calculate $I$-$V$
+curves and find qualitative agreement between our theory and recent experiments
+on $C_{60}$ single-molecule devices.",0303236v3
+2004-09-03,Weyl equation for temperature fields induced by attosecond laser pulses,"In this paper the Weyl equation for temperature field induced by laser beam
+interaction with matter is proposed and solved. Depending on the scattering
+mechanism the temperature field oscillate or is damped.
+  Key words: Thermal processes, Weyl equation",0409076v1
+2004-12-08,Spectroscopy of a driven solid-state qubit coupled to a structured environment,"We study the asymptotic dynamics of a driven spin-boson system where the
+environment is formed by a broadened localized mode. Upon exploiting an exact
+mapping, an equivalent formulation of the problem in terms of a quantum
+two-state system (qubit) coupled to a harmonic oscillator which is itself
+Ohmically damped, is found. We calculate the asymptotic population difference
+of the two states in two complementary parameter regimes. For weak damping and
+low temperature, a perturbative Floquet-Born-Markovian master equation for the
+qubit-oscillator system can be solved. We find multi-photon resonances
+corresponding to transitions in the coupled quantum system and calculate their
+line-shape analytically. In the complementary parameter regime of strong
+damping and/or high temperatures, non-perturbative real-time path integral
+techniques yield analytic results for the resonance line shape. In both
+regimes, we find very good agreement with exact results obtained from a
+numerical real-time path-integral approach. Finally, we show for the case of
+strong detuning between qubit and oscillator that the width of the $n$-photon
+resonance scales with the $n$-th Bessel function of the driving strength in the
+weak-damping regime.",0412194v2
+1995-03-08,A NEW NUMERICAL APPROACH TO THE OSCILLATION MODES OF RELATIVISTIC STARS,"The oscillation modes of a simple polytropic stellar model are studied. Using
+a new numerical approach (based on integration for complex coordinates) to the
+problem for the stellar exterior we have computed the eigenfrequencies of the
+highly damped w-modes. The results obtained agree well with recent ones of
+Leins, Nollert and Soffel (1993) Specifically, we are able to explain why
+several modes in this regime of the complex frequency plane could not be
+identified within the WKB approach of Kokkotas and Schutz (1992). Furthermore,
+we have established that the ``kink'' that was a prominent feature of the
+spectra of Kokkotas and Schutz, but did not appear in the results of Leins {\em
+et al.}, was a numerical artefact. Using our new numerical code we are also
+able to compute, for the first time, several of the slowly damped (p) modes for
+the considered stellar models. For very compact stars we find, somewhat
+surprisingly, that the damping of these modes does not decrease monotonically
+as one proceeds to higher oscillation frequencies. The existence of low-order
+modes that damp away much faster than anticipated may have implications for
+questions regarding stellar stability and the lifetime of gravitational-wave
+sources. The present results illustrate the accuracy and reliability of the
+complex-coordinate method and indicate that the method could prove to be of
+great use also in problems involving rotating stars. There is no apparent
+reason why the complex-coordinate approach should not extend to rotating stars,
+whereas it is accepted that all previous methods will fail to do so.",9503014v1
+1998-01-29,"On the gravitational, dilatonic and axionic radiative damping of cosmic strings","We study the radiation reaction on cosmic strings due to the emission of
+dilatonic, gravitational and axionic waves. After verifying the (on average)
+conservative nature of the time-symmetric self-interactions, we concentrate on
+the finite radiation damping force associated with the half-retarded minus
+half-advanced ``reactive'' fields. We revisit a recent proposal of using a
+``local back reaction approximation'' for the reactive fields. Using
+dimensional continuation as convenient technical tool, we find, contrary to
+previous claims, that this proposal leads to antidamping in the case of the
+axionic field, and to zero (integrated) damping in the case of the
+gravitational field. One gets normal positive damping only in the case of the
+dilatonic field. We propose to use a suitably modified version of the local
+dilatonic radiation reaction as a substitute for the exact (non-local)
+gravitational radiation reaction. The incorporation of such a local
+approximation to gravitational radiation reaction should allow one to complete,
+in a computationally non-intensive way, string network simulations and to give
+better estimates of the amount and spectrum of gravitational radiation emitted
+by a cosmologically evolving network of massive strings.",9801105v3
+2004-10-15,A Nonlinear Coupling Network to Simulate the Development of the r-mode Instablility in Neutron Stars II. Dynamics,"Two mechanisms for nonlinear mode saturation of the r-mode in neutron stars
+have been suggested: the parametric instability mechanism involving a small
+number of modes and the formation of a nearly continuous Kolmogorov-type
+cascade. Using a network of oscillators constructed from the eigenmodes of a
+perfect fluid incompressible star, we investigate the transition between the
+two regimes numerically. Our network includes the 4995 inertial modes up to n<=
+30 with 146,998 direct couplings to the r-mode and 1,306,999 couplings with
+detuning< 0.002 (out of a total of approximately 10^9 possible couplings).
+  The lowest parametric instability thresholds for a range of temperatures are
+calculated and it is found that the r-mode becomes unstable to modes with
+13<n<15. In the undriven, undamped, Hamiltonian version of the network the rate
+to achieve equipartition is found to be amplitude dependent, reminiscent of the
+Fermi-Pasta-Ulam problem. More realistic models driven unstable by
+gravitational radiation and damped by shear viscosity are explored next. A
+range of damping rates, corresponding to temperatures 10^6K to 10^9K, is
+considered. Exponential growth of the r-mode is found to cease at small
+amplitudes, approximately 10^-4. For strongly damped, low temperature models, a
+few modes dominate the dynamics. The behavior of the r-mode is complicated, but
+its amplitude is still no larger than about 10^-4 on average. For high
+temperature, weakly damped models the r-mode feeds energy into a sea of
+oscillators that achieve approximate equipartition. In this case the r-mode
+amplitude settles to a value for which the rate to achieve equipartition is
+approximately the linear instability growth rate.",0410072v1
+1997-02-20,Numerical study of plasmon properties in the SU(2)-Higgs model,"Using the (effective) classical approximation, we compute numerically
+time-dependent correlation functions in the SU(2)-Higgs model around the
+electroweak phase transition, for $m_H \approx m_W$. The parameters of the
+classical model have been determined previously by the dimensional reduction
+relations for time-independent correlators. The $H$ and $W$ correlation
+functions correspond to gauge invariant fields. They show damped oscillatory
+behavior from which we extract frequencies $\om$ and damping rates $\gm$. In
+the Higgs phase the damping rates have roughly the values obtained in analytic
+calculations in the quantum theory. In the plasma phase (where analytic
+estimates for gauge invariant fields are not available), the damping rate
+associated with $H$ is an order of magnitude larger than in the Higgs phase,
+while the $W$ correlator appears to be overdamped, with a small rate. The
+frequency $\om_H$ shows a clear dip at the transition. The results are
+approximately independent of the lattice spacing, but this appears to be
+compatible with the lattice spacing dependence expected from perturbation
+theory.",9702017v2
+2001-01-16,Nonlinear Landau damping of a plasmino in the quark-gluon plasma,"On the basis of the Blaizot-Iancu equations, which are a local formulation of
+the hard thermal loop (HTL) equations of motion for soft fluctuating quark and
+gluon fields and their induced sources, the coupled kinetic equations for
+plasminos and plasmons are obtained. The equality of matrix elements for
+nonlinear scattering of a plasmino by hard particles in covariant and temporal
+gauges is established by using effective Ward identities. The model problem of
+the interaction of two infinitely narrow packets with fermion and boson quantum
+numbers is considered. The kinematical relations between wave vectors of the
+plasmino and plasmon are derived, when the effective pumping over of the plasma
+excitation energy from the fermion branch of plasma excitations to the boson
+branch and vice versa occur. The expression for the nonlinear Landau damping
+rate of a plasmino at rest is found, and a comparison with a plasmino damping
+constant obtained within the framework of the hard thermal loop approximation
+is made. The nonlinear Landau damping rate for normal quark excitations is
+shown to diverge like $1/\sqrt{q^2}$ near the light cone where $q$ is a
+four-momentum of excitations, and the improved Blaizot-Iancu equations removing
+this divergence are proposed.",0101167v2
+2003-12-15,Nonequilibrium pion dynamics near the critical point in a constituent quark model,"We study static and dynamical critical phenomena of chiral symmetry breaking
+in a two-flavor Nambu--Jona-Lasinio constituent quark model. We obtain the
+low-energy effective action for scalar and pseudoscalar degrees of freedom to
+lowest order in quark loops and to quadratic order in the meson fluctuations
+around the mean field. The \emph{static} limit of critical phenomena is shown
+to be described by a Ginzburg-Landau effective action including \emph{spatial}
+gradients. Hence \emph{static} critical phenomena is described by the
+universality class of the O(4) Heisenberg ferromagnet. \emph{Dynamical}
+critical phenomena is studied by obtaining the equations of motion for pion
+fluctuations. We find that for $T<T_c$ the are stable long-wavelength pion
+excitations with dispersion relation $\omega_{\pi}(k)=k$ described by isolated
+pion poles. The residue of the pion pole vanishes near $T_c$ as $Z \propto
+1/|\ln(1-T/T_c)|$ and long-wavelength fluctuations are damped out by Landau
+damping on a time scale $t_\mathrm{rel}(k)\propto 1/k$, reflecting
+\emph{critical slowing down} of pion fluctuations near the critical point. At
+the critical point, the pion propagator features mass shell logarithmic
+divergences which we conjecture to be the harbinger of a (large) dynamical
+anomalous dimension. We find that while the \emph{classical spinodal} line
+coincides with that of the Ginzburg-Landau theory, the growth rate of
+long-wavelength spinodal fluctuations has a richer wavelength dependence as a
+consequence of Landau damping. We argue that Landau damping prevents a
+\emph{local} low energy effective action in terms of a derivative expansion in
+real time.",0312185v2
+2002-02-01,Time Domain Computation of a Nonlinear Nonlocal Cochlear Model with Applications to Multitone Interaction in Hearing,"A nonlinear nonlocal cochlear model of the transmission line type is studied
+in order to capture the multitone interactions and resulting tonal suppression
+effects. The model can serve as a module for voice signal processing, it is a
+one dimensional (in space) damped dispersive nonlinear PDE based on mechanics
+and phenomenology of hearing. It describes the motion of basilar membrane (BM)
+in the cochlea driven by input pressure waves. Both elastic damping and
+selective longitudinal fluid damping are present. The former is nonlinear and
+nonlocal in BM displacement, and plays a key role in capturing tonal
+interactions. The latter is active only near the exit boundary (helicotrema),
+and is built in to damp out the remaining long waves. The initial boundary
+value problem is numerically solved with a semi-implicit second order finite
+difference method. Solutions reach a multi-frequency quasi-steady state.
+Numerical results are shown on two tone suppression from both high-frequency
+and low-frequency sides, consistent with known behavior of two tone
+suppression. Suppression effects among three tones are demonstrated by showing
+how the response magnitudes of the fixed two tones are reduced as we vary the
+third tone in frequency and amplitude. We observe qualitative agreement of our
+model solutions with existing cat auditory neural data. The model is thus
+simple and efficient as a processing tool for voice signals.",0202004v3
+2003-12-22,Intermittency is a consequence of turbulent transport in nonlinear systems,"Intermittent high-amplitude structures emerge in a damped and driven discrete
+nonlinear Schroedinger equation whose solutions transport both energy and
+particles from sources to sinks. These coherent structures are necessary for
+any solution that has statistically stationary transport properties.",0312059v1
+2004-06-17,Multi-frequency control of Faraday wave patterns,"We show how pattern formation in Faraday waves may be manipulated by varying
+the harmonic content of the periodic forcing function. Our approach relies on
+the crucial influence of resonant triad interactions coupling pairs of critical
+standing wave modes with damped, spatio-temporally resonant modes. Under the
+assumption of weak damping and forcing, we perform a symmetry-based analysis
+that reveals the damped modes most relevant for pattern selection, and how the
+strength of the corresponding triad interactions depends on the forcing
+frequencies, amplitudes, and phases. In many cases, the further assumption of
+Hamiltonian structure in the inviscid limit determines whether the given triad
+interaction has an enhancing or suppressing effect on related patterns.
+Surprisingly, even for forcing functions with arbitrarily many frequency
+components, there are at most five frequencies that affect each of the
+important triad interactions at leading order. The relative phases of those
+forcing components play a key role, sometimes making the difference between an
+enhancing and suppressing effect. In numerical examples, we examine the
+validity of our results for larger values of the damping and forcing. Finally,
+we apply our findings to one-dimensional periodic patterns obtained with
+impulsive forcing and to two-dimensional superlattice patterns and
+quasipatterns obtained with multi-frequency forcing.",0406034v1
+1997-01-22,Shell Model for Warm Rotating Nuclei,"In order to provide a microscopic description of levels and E2 transitions in
+rapidly rotating nuclei with internal excitation energy up to a few MeV, use is
+made of a shell model which combines the cranked Nilsson mean-field and the
+residual surface delta two-body force. The damping of collective rotational
+motion is investigated in the case of a typical rare-earth nucleus, namely \Yb.
+It is found that rotational damping sets in at around 0.8 MeV above the yrast
+line, and the levels which form rotational band structures are thus limited. We
+predict at a given rotational frequency existence of about 30 rotational bands
+of various lengths, in overall agreement with the experimental findings. The
+onset of the rotational damping proceeds quite gradually as a function of the
+internal excitation energy. The transition region extends up to around 2 MeV
+above yrast and it is characterized by the presence of scars of discrete
+rotational bands which extend over few spin values and stand out among the
+damped transitions, and by a two-component profile in the $E_\gamma -E_\gamma$
+correlation. The important role played by the high-multipole components of the
+two-body residual interaction is emphasized.",9701044v1
+2005-04-21,Enhanced optical cooling of particle beams in storage rings,"The problem of enhanced optical cooling (EOC) of particle beams in storage
+rings beyond the Robinson's damping criterion is discussed.",0504145v1
+2005-10-21,Non-contact atomic force microscopy: Stability criterion and dynamical responses of the shift of frequency and damping signal,"The aim of this article is to provide a complete analysis of the behavior of
+a noncontact atomic force microscope (NC-AFM). We start with a review of the
+equations of motion of a tip interacting with a surface in which the stability
+conditions are first revisited for tapping mode. Adding the equations of
+automatic gain control (AGC), which insures constant amplitude of the
+oscillations in the NC-AFM, to the equations of motion of the tip, a new
+analytical stability criterion that involves proportional and integral gains of
+AGC is deduced. Stationary solutions for the shift of frequency and for the
+damping signal are obtained. Special attention is paid to the damping signal in
+order to clarify its physical origin. The theoretical results are then compared
+to those given by a virtual machine. The virtual machine is a set of equations
+solved numerically without any approximation. The virtual machine is of great
+help in understanding the dynamical behavior of the NC-AFM as images are
+recorded. Transient responses of the shift in frequency and of the damping
+signal are discussed in relation to the values of proportional and integral
+gains of AGC.",0510192v1
+1999-06-09,Quantum dynamics of a damped deformed oscillator,"The interaction of a quantum deformed oscillator with the environment is
+studied deriving a master equation whose form strongly depends on the type of
+deformation.",9906031v1
+2007-04-29,Long Term Evolution of Magnetic Turbulence in Relativistic Collisionless Shocks: Electron-Positron Plasmas,"We study the long term evolution of magnetic fields generated by a
+collisionless relativistic $e^+e^-$ shock which is initially unmagnetized. Our
+2D particle-in-cell numerical simulations show that downstream of such a
+Weibel-mediated shock, particle distributions are close to isotropic,
+relativistic Maxwellians, and the magnetic turbulence is highly intermittent
+spatially, with the non-propagating magnetic fields forming relatively isolated
+regions with transverse dimension $\sim 10-20$ skin depths. These structures
+decay in amplitude, with little sign of downstream merging. The fields start
+with magnetic energy density $\sim (0.1-0.2)$ of the upstream kinetic energy
+within the shock transition, but rapid downstream decay drives the fields to
+much smaller values, below $10^{-3}$ of equipartition after $10^3$ skin depths.
+  In an attempt to construct a theory that follows field decay to these smaller
+values, we explore the hypothesis that the observed damping is a variant of
+Landau damping in an unmagnetized plasma. The model is based on the small value
+of the downstream magnetic energy density, which suggests that particle orbits
+are only weakly perturbed from straight line motion, if the turbulence is
+homogeneous. Using linear kinetic theory applied to electromagnetic fields in
+an isotropic, relativistic Maxwellian plasma, we find a simple analytic form
+for the damping rates, $\gamma_k$, in two and three dimensions for small
+amplitude, subluminous electromagnetic fields. We find that magnetic energy
+does damp due to phase mixing of current carrying particles as $(\omega_p
+t)^{-q}$ with $q \sim 1$. (abridged)",0704.3832v2
+2007-06-21,Production of a sterile species via active-sterile mixing: an exactly solvable model,"The production of a sterile species via active-sterile mixing in a thermal
+medium is studied in an exactly solvable model. The \emph{exact} time evolution
+of the sterile distribution function is determined by the dispersion relations
+and damping rates $\Gamma_{1,2}$ for the quasiparticle modes. These depend on
+$\wtg = \Gamma_{aa}/2\Delta E$, with $\Gamma_{aa}$ the interaction rate of the
+active species in absence of mixing and $\Delta E$ the oscillation frequency in
+the medium without damping. $\wtg \ll1,\wtg \gg 1$ describe the weak and strong
+damping limits respectively. For $\wtg\ll1$, $\Gamma_1 = \Gamma_{aa}\cos^2\tm ;
+\Gamma_{2}=\Gamma_{aa}\sin^2\tm$ where $\tm$ is the mixing angle in the medium
+and the sterile distribution function \emph{does not} obey a simple rate
+equation. For $\wtg \gg 1$, $\Gamma_1= \Gamma_{aa}$ and $\Gamma_2 = \Gamma_{aa}
+\sin^22\tm/4\wtg^2$, is the sterile production rate. In this regime sterile
+production is suppressed and the oscillation frequency \emph{vanishes} at an
+MSW resonance, with a breakdown of adiabaticity. These are consequences of
+quantum Zeno suppression. For active neutrinos with standard model interactions
+the strong damping limit is \emph{only} available near an MSW resonance
+\emph{if} $\sin\theta \lesssim \alpha_w$ with $\theta$ the vacuum mixing angle.
+The full set of quantum kinetic equations for sterile production for arbitrary
+$\wtg$ are obtained from the quantum master equation. Cosmological resonant
+sterile neutrino production is quantum Zeno suppressed relieving potential
+uncertainties associated with the QCD phase transition.",0706.3167v2
+2007-08-02,Eccentricity evolution of giant planet orbits due to circumstellar disk torques,"The extrasolar planets discovered to date possess unexpected orbital
+elements. Most orbit their host stars with larger eccentricities and smaller
+semi-major axes than similarly sized planets in our own solar system do. It is
+generally agreed that the interaction between giant planets and circumstellar
+disks (Type II migration) drives these planets inward to small radii, but the
+effect of these same disks on orbital eccentricity, e, is controversial.
+Several recent analytic calculations suggest that disk-planet interactions can
+excite eccentricity, while numerical studies generally produce eccentricity
+damping. This paper addresses this controversy using a quasi-analytic approach,
+drawing on several preceding analytic studies. This work refines the current
+treatment of eccentricity evolution by removing several approximations from the
+calculation of disk torques. We encounter neither uniform damping nor uniform
+excitation of orbital eccentricity, but rather a function de/dt that varies in
+both sign and magnitude depending on eccentricity and other solar system
+properties. Most significantly, we find that for every combination of disk and
+planet properties investigated herein, corotation torques produce negative
+values of de/dt for some range in e within the interval [0.1, 0.5]. If
+corotation torques are saturated, this region of eccentricity damping
+disappears, and excitation occurs on a short timescale of less than 0.08 Myr.
+Thus, our study does not produce eccentricity excitation on a timescale of a
+few Myr -- we obtain either eccentricity excitation on a short time scale, or
+eccentricity damping on a longer time scale. Finally, we discuss the
+implications of this result for producing the observed range in extrasolar
+planet eccentricity.",0708.0335v1
+2007-10-10,HE 0515-4414 - an unusual sub-damped Ly alpha system revisited,"Using STIS and VLT UVES observations we have examined the ionization,
+abundances, and differential dust depletion of metals, the kinematic structure,
+and the physical conditions in the molecular hydrogen-bearing sub-damped Ly
+alpha system toward HE 0515-4414 at z = 1.15. The velocity interval of
+associated metal lines extends for 700 km/s. In addition, saturated H I
+absorption is detected in the blue damping wing of the main component. The
+column density ratios of associated Al II, Al III, and Fe II lines indicate
+that the absorbing material is ionized. 19 of in total 31 detected metal line
+components are formed within peripheral H II regions, while only 12 components
+are associated with the predominantly neutral main absorber. For the main
+absorber the observed abundance ratios of refractory elements to Zn range from
+Galactic warm disk [Si/Zn] = - 0.40, [Fe/Zn] = -1.10 to halo-like and
+essentially undepleted patterns. The dust-corrected metal abundances indicate a
+nucleosynthetic odd-even effect and might imply an anomalous depletion of Si
+relative to Fe for two components, but otherwise do correspond to solar ratios.
+The intrinsic average metallicity is almost solar [Fe/H] = -0.08, whereas the
+uncorrected average is [Zn/H] = -0.38. The ion abundances in the periphery
+conform with solar element composition. The detection of H II as well as the
+large variation in dust depletion for this sight line raises the question
+whether in future studies of damped Ly alpha systems ionization and depletion
+effects have to be considered in further detail. Ionization effects, for
+instance, may pretend an enrichment of alpha elements. An empirical recipe for
+detecting H II regions is provided.",0710.3560v1
+2008-06-05,Viscous damping of r-mode oscillations in compact stars with quark matter,"We determine characteristic timescales for the viscous damping of r-mode
+oscillations in rapidly rotating compact stars that contain quark matter. We
+present results for the color-flavor-locked (CFL) phase of dense quark matter,
+in which the up, down and strange quarks are gapped, as well as the normal
+(ungapped) quark phase. While the ungapped quark phase supports a temperature
+window between 10^8 K and 5x10^9 K where the r-mode is damped even for rapid
+rotation, the r-mode in a rapidly rotating pure CFL star is not damped in the
+temperature range 10^10 K - 10^11 K. Rotating hybrid stars with quark matter
+cores display an instability window whose width is determined by the amount of
+quark matter present, and they can have large spin frequencies outside this
+window. Except at high temperatures T > 10^10 K, the presence of a quark phase
+allows for larger critical frequencies and smaller spin-periods compared to
+rotating neutron stars. If low-mass X-ray binaries contain a large amount of
+ungapped or CFL quark matter, then our estimates of the r-mode instability
+suggest that there should be a population of rapidly rotating binaries at
+frequencies greater than 1000 Hz which have not yet been observed.",0806.1005v2
+2008-06-09,Relaxation Time and Relaxation Function of Quark-Gluon Plasma with Lattice QCD,"We propose a method which enables a QCD-based calculation of a relaxation
+time for a dissipative current in the causal and dissipative hydrodynamic
+equation derived by Israel and Stewart. We point out that the Israel-Stewart
+equation is not unique as a causal and dissipative hydrodynamic equation, and
+the form of the causal and dissipative hydrodynamic equation is determined by
+the shape of a spectral function reflecting the properties of elementary
+excitations in the system we consider. Our method utilizes a relaxation
+function, which can be calculated from QCD using the linear response theory. We
+show that the relaxation function can be derived from a spectral function for a
+microscopic representation of the dissipative current. We also show that the
+Israel-Stewart equation is acceptable only as long as the calculated relaxation
+function is approximated well by a exponentially damping function, and the
+relaxation time can be obtained as its damping time constant. Taking a
+baryon-number dissipative current of a plasma consisting of charm quarks and
+gluons as a simple example, we present the first calculation of the relaxation
+function with use of the spectral function derived employing the quenched
+lattice QCD together with the maximum entropy method. The calculated relaxation
+function shows a strongly-oscillation damping behaviour due to the charmed
+vector hadron $J/\Psi$ surviving above the deconfinement phase transition
+temperature in QCD. This result suggests that the applicability of the
+Israel-Stewart equation to the baryon-number dissipative current of the charm
+quark-gluon plasma is quite doubtful. We present an idea for the improvement of
+the Israel-Stewart equation by deriving the hydrodynamic equation consistent
+with the strongly-oscillation damping relaxation function.",0806.1481v1
+2008-06-18,Imaging method for interface rheological characterization,"The present work investigates free damped oscillations of an oil drop in
+water after its release from a capillary tube. Both pure heptane drops and
+diluted crude oil drops are considered (in the second case the interface is
+covered by amphiphilic species, natural components of crude oil). Shadowgraph
+images of the drops are taken by means of a high speed camera and the drop
+contour is detected by image processing. The axisymmetric drop shape is then
+decomposed into spherical harmonics, which constitute the eigenmodes of
+oscillations predicted by the Rayleigh-Lamb theory. Time evolution of each mode
+is then obtained. The frequency and the damping rate of the principal mode
+(n=2) are accurately determined and compared with theoretical values for an
+immobile clean drop oscillating around spherical shape. For pure heptane drops,
+theoretical value of the frequency agrees well with experiments whereas the
+damping rate is significantly underestimated by theory. The experimental
+results clearly show that the different modes are coupled. Energy is thus
+transfered from mode n=2 to n=3, which probably explains the observed
+enhancement of the damping rate. The effect of the interface viscoelastic
+behaviour, induced by adsorbed amphiphilic species on the free oscillations was
+examined. No significant effect was observed in the experiments conditions
+(small amplitude oscillations and moderate aging).",0806.3030v1
+2008-06-27,Klein - Gordon equation for market wealth operations,"In this paper the modified Klein - Gordon equation for market processes is
+proposed and solved. It is argued that the oscillations in market propagate
+with the light velocity. The initial pulse in the market is damped and for very
+large time diffused according to the Fourier law.",0806.4466v1
+2008-10-22,"Mean Motion Resonances in Extrasolar Planetary Systems with Turbulence, Interactions, and Damping","This paper continues previous work on the effects of turbulence on mean
+motion resonances in extrasolar planetary systems. Turbulence is expected to
+arise in the disks that form planets, and these fluctuations act to compromise
+resonant configurations. This paper extends previous work by considering how
+interactions between the planets and possible damping effects imposed by the
+disk affect the outcomes. These physical processes are studied using three
+approaches: numerical integrations of the 3-body problem with additional
+forcing due to turbulence, model equations that reduce the problem to
+stochastically driven oscillators, and Fokker-Planck equations that describe
+the time evolution of an ensemble of systems. With this combined approach, we
+elucidate the physics of how turbulence can remove extrasolar planetary systems
+from mean motion resonance. As expected, systems with sufficiently large
+damping (dissipation) can maintain resonance, in spite of turbulent forcing. In
+the absence of strong damping, ensembles of these systems exhibit two regimes
+of behavior, where the fraction of the bound states decreases as a power-law or
+as an exponential. Both types of behavior can be understood through the model
+developed herein. For systems with weak interactions between planets, the model
+reduces to a stochastic pendulum, and the fraction of bound states decreases as
+a power-law. For highly interactive systems, the dynamics are more complicated
+and the fraction of bound states decreases exponentially. We show how planetary
+interactions lead to drift terms in the Fokker-Planck equation and account for
+this exponential behavior. In addition to clarifying the physical processes
+involved, this paper strengthens the finding that turbulence implies that mean
+motions resonances should be rare.",0810.4076v1
+2009-01-11,On the derivation of structural models with general thermomechanical prestress,"The vibrating behaviour of thin structures is affected by prestress states.
+Hence, the effects of thermal prestress are important research subjects in view
+of ambient vibration monitoring of civil structures. The interaction between
+prestress, geometrically non-linear behaviour, as well as damping and its
+coupling with the aforementioned phenomena has to be taken into account for a
+comprehensive understanding of the structural behaviour. Since the literature
+on this subject lacks a clear procedure to derive models of thin prestressed
+and damped structures from 3D continuum mechanics, this paper presents a new
+derivation of models for thin structures accounting for generic prestress,
+moderate rotations and viscous damping. Although inspired by classical
+approaches, the proposed procedure is quite different, because of (i) the
+definition of a modified Hu-Washizu (H-W) functional, accounting for stress
+constraints associated with Lagrange multipliers, in order to derive
+lower-dimensional models in a convenient way; (ii) an original definition of a
+(mechanical and thermal) strain measure and a rotation measure enabling one to
+identify the main terms in the strain energy and to derive a cascade of
+lower-dimensional models (iii) a new definition of ""strain-rotation domains""
+providing a clear interpretation of the classical assumptions of ""small
+perturbations"" and ""small strains and moderate rotations""; (iv) the
+introduction of a pseudo-potential with stress constraints to account for
+viscous damping. The proposed procedure is applied to thin beams.",0901.1446v1
+2009-04-17,On Landau damping,"Going beyond the linearized study has been a longstanding problem in the
+theory of Landau damping. In this paper we establish exponential Landau damping
+in analytic regularity. The damping phenomenon is reinterpreted in terms of
+transfer of regularity between kinetic and spatial variables, rather than
+exchanges of energy; phase mixing is the driving mechanism. The analysis
+involves new families of analytic norms, measuring regularity by comparison
+with solutions of the free transport equation; new functional inequalities; a
+control of nonlinear echoes; sharp scattering estimates; and a Newton
+approximation scheme. Our results hold for any potential no more singular than
+Coulomb or Newton interaction; the limit cases are included with specific
+technical effort. As a side result, the stability of homogeneous equilibria of
+the nonlinear Vlasov equation is established under sharp assumptions. We point
+out the strong analogy with the KAM theory, and discuss physical implications.",0904.2760v5
+2009-07-27,Parameter exploration of optically trapped liquid aerosols,"When studying the motion of optically trapped particles on the $\mu s$ time
+scale, in low viscous media such as air, inertia cannot be neglected.
+Resolution of unusual and interesting behaviour not seen in colloidal trapping
+experiments is possible. In attempt to explain the phenomena we use power
+spectral methods to perform a parameter study of the Brownian motion of
+optically trapped liquid aerosol droplets concentrated around the critically
+damped regime. We present evidence that the system is suitably described by a
+simple harmonic oscillator model which must include a description of
+Fax\'{e}n's correction, but not necessarily frequency dependent hydrodynamic
+corrections to Stokes' law. We also provide results describing how the system
+behaves under several variables and discuss the difficulty in decoupling the
+parameters responsible for the observed behaviour. We show that due to the
+relatively low dynamic viscosity and high trap stiffness it is easy to transfer
+between over- and under-damped motion by experimentally altering either trap
+stiffness or damping. Our results suggest stable aerosol trapping may be
+achieved in under-damped conditions, but the onset of deleterious optical
+forces at high trapping powers prevents the probing of the upper stability
+limits due to Brownian motion.",0907.4582v2
+2010-06-19,On the saturation amplitude of the f-mode instability,"We investigate strong nonlinear damping effects which occur during high
+amplitude oscillations of neutron stars, and the gravitational waves they
+produce. For this, we use a general relativistic nonlinear hydrodynamics code
+in conjunction with a fixed spacetime (Cowling approximation) and a polytropic
+equation of state (EOS). Gravitational waves are estimated using the quadrupole
+formula. Our main interest are l=m=2 f modes subject to the CFS (Chandrasekhar,
+Friedman, Schutz) instability, but we also investigate axisymmetric and
+quasiradial modes. We study various models to determine the influence of
+rotation rate and EOS. We find that axisymmetric oscillations at high
+amplitudes are predominantly damped by shock formation, while the
+nonaxisymmetric f modes are mainly damped by wave breaking and, for rapidly
+rotating models, coupling to nonaxisymmetric inertial modes. From the observed
+nonlinear damping, we derive upper limits for the saturation amplitude of
+CFS-unstable f modes. Finally, we estimate that the corresponding gravitational
+waves for an oscillation amplitude at the upper limit should be detectable with
+the advanced LIGO and VIRGO interferometers at distances above 10 MPc. This
+strongly depends on the stellar model, in particular on the mode frequency.",1006.3885v2
+2010-07-06,Magneto-elastic oscillations and the damping of crustal shear modes in magnetars,"In a realistic model of magneto-elastic oscillations in magnetars, we find
+that crustal shear oscillations, often invoked as an explanation of
+quasi-periodic oscillations (QPOs) seen after giant flares in soft gamma-ray
+repeaters (SGRs), are damped by resonant absorption on timescales of at most
+0.2s, for a lower limit on the dipole magnetic field strength of 5 x 10^13 G.
+At higher magnetic field strengths (typical in magnetars) the damping timescale
+is even shorter, as anticipated by earlier toy-models. We have investigated a
+range of equations of state and masses and if magnetars are dominated by a
+dipole magnetic field, our findings exclude torsional shear oscillations of the
+crust from explaining the observed low-frequency QPOs. In contrast, we find
+that the Alfv\'en QPO model is a viable explanation of observed QPOs, if the
+dipole magnetic field strength exceeds a minimum strength of about several
+times 10^14 G to 10^15 G. Then, Alfv\'en QPOs are no longer confined to the
+fluid core, but completely dominate in the crust region and have a maximum
+amplitude at the surface of the star.",1007.0856v2
+2010-08-16,Orbital evolution of eccentric planets in radiative discs,"With an average eccentricity of about 0.29, the eccentricity distribution of
+extrasolar planets is markedly different from the solar system. Among other
+scenarios considered, it has been proposed that eccentricity may grow through
+planet-disc interaction. Recently, it has been noticed that the thermodynamical
+state of the disc can significantly influence the migration properties of
+growing protoplanets. However, the evolution of planetary eccentricity in
+radiative discs has not been considered yet. In this paper we study the
+evolution of planets on eccentric orbits that are embedded in a
+three-dimensional viscous disc and analyse the disc's effect on the orbital
+evolution of the planet. We use the three-dimensional hydrodynamical code
+NIRVANA that includes full tensor viscosity and implicit radiation transport in
+the flux-limited diffusion approximation. The code uses the FARGO-algorithm to
+speed up the simulations. First we measure the torque and power exerted on the
+planet by the disc for fixed orbits, and then we let the planet start with
+initial eccentricity and evolve it in the disc. For locally isothermal we
+confirm previous results and find eccentricity damping and inward migration for
+planetary cores. In the case of radiative discs, the planets experience an
+inward migration as long as its eccentricity lies above a certain threshold.
+After the damping of eccentricity cores with masses below 33 Earthmasses begin
+to migrate outward in radiative discs, while higher mass cores always migrate
+inward. For all planetary masses studied (up to 200 Earthmasses) we find
+eccentricity damping. In viscous discs the orbital eccentricity of embedded
+planets is damped during the evolution independent of the mass. Hence,
+planet-disc interaction does not seem to be a viable mechanism to explain the
+observed high eccentricity of exoplanets.",1008.2656v1
+2010-11-02,A Carbon-enhanced Metal-poor Damped Lyman alpha System: Probing Gas from Population III Nucleosynthesis?,"We present high resolution observations of an extremely metal-poor damped
+Lyman-alpha system, at z_abs = 2.3400972 in the spectrum of the QSO J0035-0918,
+exhibiting an abundance pattern consistent with model predictions for the
+supernova yields of Population III stars. Specifically, this DLA has [Fe/H] =
+-3.04, shows a clear `odd-even' effect, and is C-rich with [C/Fe] = +1.53, a
+factor of about 20 greater than reported in any other damped Lyman-alpha
+system. In analogy to the carbon-enhanced metal-poor stars in the Galactic halo
+(with [C/Fe] > +1.0), this is the first reported case of a carbon-enhanced
+damped Lyman-alpha system. We determine an upper limit to the mass of 12C,
+M(12C) < 200 solar masses, which depends on the unknown gas density n(H); if
+n(H) > 1 atom per cubic cm (which is quite likely for this DLA given its low
+velocity dispersion), then M(12C) < 2 solar masses, consistent with pollution
+by only a few prior supernovae. We speculate that DLAs such as the one reported
+here may represent the `missing link' between the yields of Pop III stars and
+their later incorporation in the class of carbon-enhanced metal-poor stars
+which show no enhancement of neutron-capture elements (CEMP-no stars).",1011.0733v2
+2010-11-08,Exponential stabilization without geometric control,"We present examples of exponential stabilization for the damped wave equation
+on a compact manifold in situations where the geometric control condition is
+not satisfied. This follows from a dynamical argument involving a topological
+pressure on a suitable uncontrolled set.",1011.1699v1
+2010-11-11,Damping of longitudinal magneto-acoustic oscillations in slowly varying coronal plasma,"We investigate the propagation of MHD waves in a homogenous, magnetized
+plasma in a weakly stratified atmosphere, representing hot coronal loops. In
+most of earlier studies a time-independent equilibrium is considered. Here we
+abandon this restriction and allow the equilibrium to develop as function of
+time. In particular, the background plasma is assumed to be cooling due to
+thermal conduction. The cooling is assumed to be on a time scale greater than
+the characteristic travel times of the perturbations. We investigate the
+influence of cooling of the background plasma on the properties of
+magneto-acoustic waves. The MHD equations are reduced to a 1-D system modelling
+magneto-acoustic modes progressing along a dynamically cooling coronal loop. A
+time dependent dispersion relation which describes the propagation of the
+magneto-acoustic waves is derived by using the WKB theory. An analytic solution
+for the time-dependent amplitude of waves is obtained and the method of
+characteristics is used to find an approximate analytical solution. Numerical
+calculations are applied to the analytically derived solutions to obtain
+further insight into the behavior of the MHD waves in a system with variable,
+time-dependent background. The results show that there is a strong damping of
+MHD waves that can be linked to the widely observed damping of hot coronal loop
+oscillations. The damping also appears to be independent of position along the
+loop. Studies of MHD wave behaviour in time-dependent background seem to be a
+fundamental and very important next step in developing MHD wave theory
+applicable to a wide range in solar physics.",1011.2617v1
+2010-12-17,Optimal switching of a nanomagnet assisted by microwaves,"We develop an efficient and general method for optimizing the microwave field
+that achieves magnetization switching with a smaller static field. This method
+is based on optimal control and renders an exact solution for the 3D microwave
+field that triggers the switching of a nanomagnet with a given anisotropy and
+in an oblique static field. Applying this technique to the particular case of
+uniaxial anisotropy, we show that the optimal microwave field, that achieves
+switching with minimal absorbed energy, is modulated both in frequency and in
+magnitude. Its role is to drive the magnetization from the metastable
+equilibrium position towards the saddle point and then damping induces the
+relaxation to the stable equilibrium position. For the pumping to be efficient,
+the microwave field frequency must match at the early stage of the switching
+process the proper precession frequency of the magnetization, which depends on
+the magnitude and direction of the static field. We investigate the effect of
+the static field (in amplitude and direction) and of damping on the
+characteristics of the microwave field. We have computed the switching curves
+in the presence of the optimal microwave field. The results are in qualitative
+agreement with micro-SQUID experiments on isolated nanoclusters. The strong
+dependence of the microwave field and that of the switching curve on the
+damping parameter may be useful in probing damping in various nanoclusters.",1012.3901v1
+2010-12-22,PageRank for ranking authors in co-citation networks,"Google's PageRank has created a new synergy to information retrieval for a
+better ranking of Web pages. It ranks documents depending on the topology of
+the graphs and the weights of the nodes. PageRank has significantly advanced
+the field of information retrieval and keeps Google ahead of competitors in the
+search engine market. It has been deployed in bibliometrics to evaluate
+research impact, yet few of these studies focus on the important impact of the
+damping factor (d) for ranking purposes. This paper studies how varied damping
+factors in the PageRank algorithm can provide additional insight into the
+ranking of authors in an author co-citation network. Furthermore, we propose
+weighted PageRank algorithms. We select 108 most highly cited authors in the
+information retrieval (IR) area from the 1970s to 2008 to form the author
+co-citation network. We calculate the ranks of these 108 authors based on
+PageRank with damping factor ranging from 0.05 to 0.95. In order to test the
+relationship between these different measures, we compare PageRank and weighted
+PageRank results with the citation ranking, h-index, and centrality measures.
+We found that in our author co-citation network, citation rank is highly
+correlated with PageRank's with different damping factors and also with
+different PageRank algorithms; citation rank and PageRank are not significantly
+correlated with centrality measures; and h-index is not significantly
+correlated with centrality measures.",1012.4872v1
+2011-01-20,Magnetohydrodynamic waves in solar partially ionized plasmas: two-fluid approach,"We derive the dynamics of magnetohydrodynamic waves in two-fluid partially
+ionized plasmas and to compare the results with those obtained under
+single-fluid description. Two-fluid magnetohydrodynamic equations are used,
+where ion-electron plasma and neutral particles are considered as separate
+fluids. Dispersion relations of linear magnetohydrodynamic waves are derived
+for simplest case of homogeneous medium. Frequencies and damping rates of waves
+are obtained for different parameters of background plasma. We found that two-
+and single-fluid descriptions give similar results for low frequency waves.
+However, the dynamics of MHD waves in two-fluid approach is significantly
+changed when the wave frequency becomes comparable or higher than ion-neutral
+collision frequency. Alfven and fast magneto-acoustic waves attain their
+maximum damping rate at particular frequencies (for example, the peak frequency
+equals 2.5 ion-neutral collision frequency for 50 % of neutral Hydrogen) in
+wave spectrum. The damping rates are reduced for higher frequency waves. The
+new mode of slow magneto-acoustic wave appears for higher frequency branch,
+which is connected to neutral hydrogen fluid. The single-fluid approach
+perfectly deals with slow processes in partially ionized plasmas, but fails for
+time-scales smaller than ion-neutral collision time. Therefore, two-fluid
+approximation should be used for the description of relatively fast processes.
+Some results of single-fluid description, for example the damping of
+high-frequency Alfven waves in the solar chromosphere due to ion-neutral
+collisions, should be revised in future.",1101.3913v1
+2011-08-25,Characterizing Multi-planet Systems with Classical Secular Theory,"Classical secular theory can be a powerful tool to describe the qualitative
+character of multi-planet systems and offer insight into their histories. The
+eigenmodes of the secular behavior, rather than current orbital elements, can
+help identify tidal effects, early planet-planet scattering, and dynamical
+coupling among the planets, for systems in which mean-motion resonances do not
+play a role. Although tidal damping can result in aligned major axes after all
+but one eigenmode have damped away, such alignment may simply be fortuitous. An
+example of this is 55 Cancri (orbital solution of Fischer et al., 2008) where
+multiple eigenmodes remain undamped. Various solutions for 55 Cancri are
+compared, showing differing dynamical groupings, with implications for the
+coupling of eccentricities and for the partitioning of damping among the
+planets. Solutions for orbits that include expectations of past tidal evolution
+with observational data, must take into account which eigenmodes should be
+damped, rather than expecting particular eccentricities to be near zero.
+Classical secular theory is only accurate for low eccentricity values, but
+comparison with other results suggests that it can yield useful qualitative
+descriptions of behavior even for moderately large eccentricity values, and may
+have advantages for revealing underlying physical processes and, as large
+numbers of new systems are discovered, for triage to identify where more
+comprehensive dynamical studies should have priority.",1108.5149v2
+2011-09-12,Nonlinear spectroscopy of superconducting anharmonic resonators,"We formulate a model for the steady state response of a nonlinear quantum
+oscillator structure, such as those used in a variety of superconducting qubit
+experiments, when excited by a steady, but not necessarily small, ac tone. We
+show that this model can be derived directly from a circuit description of some
+recent qubit experiments in which the state of the qubit is read out directly,
+without a SQUID magnetometer. The excitation profile has a rich structure
+depending on the detuning of the tone from the small-signal resonant frequency,
+on the degree of damping, and on the excitation amplitude. We explore two
+regions in detail: First, at high damping there is a trough in the excitation
+response as a function of detuning, near where the classical Duffing
+bifurcation occurs. This trough has been understood as a classical interference
+between two metastable responses with opposite phase. We use Wigner function
+studies to show that while this picture is roughly correct, there are also more
+quantum mechanical aspects to this feature. Second, at low damping we study the
+emergence of sharp, discrete spectral features from a continuum response. We
+show that these the structures, associated with discrete transitions between
+different excited-state eigenstates of the oscillator, provide an interesting
+example of a quantum Fano resonance. The trough in the Fano response evolves
+continuously from the ""classical"" trough at high damping.",1109.2490v1
+2012-04-09,The Kato Smoothing Effect for Regularized Schrödinger Equations in Exterior Domains,"We prove, under the exterior geometric control condition, the Kato smoothing
+effect for solutions of an inhomogenous and damped Schr\""odinger equation on
+exterior domains.",1204.1904v1
+2012-04-26,Well-posedness and long time behavior in nonlinear dissipative hyperbolic-like evolutions with critical exponents,"These lectures present the analysis of stability and control of long time
+behavior of PDE models described by nonlinear evolutions of hyperbolic type.
+Specific examples of the models under consideration include: (i) nonlinear
+systems of dynamic elasticity: von Karman systems, Berger's equations,
+Kirchhoff - Boussinesq equations, nonlinear waves (ii) nonlinear flow -
+structure and fluid - structure interactions, (iii) and nonlinear
+thermo-elasticity. A characteristic feature of the models under consideration
+is criticality or super-criticality of sources (with respect to Sobolev's
+embeddings) along with super-criticality of damping mechanisms which, in
+addition, may be also geometrically constrained.
+  Our aim is to present several methods relying on cancelations, harmonic
+analysis and geometric analysis, which enable to handle criticality and also
+super-criticality in both sources and the damping of the underlined nonlinear
+PDE. It turns out that if carefully analyzed the nonlinearity can be taken
+""advantage of"" in order to produce implementable damping mechanism.
+  Another goal of these lectures is the understanding of control mechanisms
+which are geometrically constrained. The final task boils down to showing that
+appropriately damped system is ""quasi-stable"" in the sense that any two
+trajectories approach each other exponentially fast up to a compact term which
+can grow in time. Showing this property- formulated as quasi-stability estimate
+-is the key and technically demanding issue that requires suitable tools. These
+include: weighted energy inequalities, compensated compactness, Carleman's
+estimates and some elements of microlocal analysis.",1204.5864v1
+2012-06-15,"Comment on ""Anisotropic Critical Magnetic Fluctuations in the Ferromagnetic Superconductor UCoGe""","We have presented the potential explanation of nonvanishing at q=0 Landau
+damping measured experimentally in ferromagnetic compounds UGe2 and UCoGe based
+on possible intersection of the Fermi sheets corresponding different bands.",1206.3468v1
+2012-06-21,Interaction between an Isotropic Nanoparticle and Drifting Electrons in a Quantum Well,"A hybrid system composed of an isotropic nanoparticle and a semiconductor
+heterostructure with a quantum well has been considered. The nanoparticle is
+supposed to be polarizable in an external electric field. A theoretical model
+of the hybrid system is substantiated and formulated. Exact solutions of the
+model equations are obtained. The frequencies of charge oscillations in the
+hybrid system and their damping owing to the dipole--plasmon interaction are
+found, the damping mechanism being similar to that of Landau damping. The
+space-time behavior of concentration perturbations in the two-dimensional
+electron gas is analyzed, and the polarization oscillations of a nanoparticle
+are studied. The induced polarization of a nanoparticle at nonzero electron
+drift velocities is found to have a complicated dynamics. In particular, the
+polarization vector circulates along elliptic trajectories for two of three
+frequency dispersion branches. If the electric current flows through the
+quantum well due to an applied electric field, the damping of oscillations in
+the hybrid system is replaced by their growth in time, which corresponds to the
+electric instability of the system. New phenomena in hybrid systems can be used
+to excite the emission of nanoparticles by an electric current and to
+electrically stimulate the emission in the terahertz spectral range.",1206.4782v1
+2012-10-02,Coherence and Stimulated Emission in the Tavis-Cummings Model: A Quantum Description of the Free Induction Signal and Radiation Damping in Magnetic Resonance,"We numerically solve the Liouville equation for the Tavis Cummings model of
+multiple spins coupled to a lossless single mode cavity, starting from an
+initial condition with small numbers of fully polarized spins tipped by a
+specified angle, and the cavity in its ground Fock state. Time evolution of the
+magnetizations and cavity states, following small to medium nutation by a
+classical field, yields a microscopic quantum mechanical picture of radiation
+damping in magnetic resonance, and the formation of the free induction signal,
+that is, the transfer of Zeeman energy, via spin coherence, to cavity
+coherence. Although the motion of the Bloch vector is nonclassical, our quantum
+description is related to the macroscopic picture of NMR reception, by showing
+the close relationship between the usual radiation damping constant, and the
+quantum mechanical Rabi nutation frequency (as enhanced by cavity coupling and
+stimulated emission.) That is, each is the product, of a nutation rate per
+oscillator current, and a current. Although the current in the damping constant
+is explicitly limited by cavity losses, which do not enter the formula for the
+Rabi frequency, we nonetheless show (in an appendix) how these losses can be
+introduced into our problem by means of a master equation. Numerical solution
+of the classical Bloch-Kirchhoff equations reinforces the conclusion that the
+strength of the free induction",1210.0868v2
+2012-10-11,Experimental estimations of viscoelastic properties of multilayer damped plates in broad-band frequency range,"Regarding lightweighting structures for aeronautics, automotive or
+construction applications, the level of performance of solutions proposed in
+terms of damping and isolation is fundamental. Hence multilayered plate appears
+as an interesting answer if damping performances are properly optimized. In
+this paper, a novel modal analysis method (Ege et al, JSV 325 (4-5), 2009) is
+used to identify viscoelastic properties (loss factors, Young's modulus) of
+""polyethylene thermoplastic / aluminum"" bilayer plates. The thermoplastic is
+chosen for its high loss factors and relative low mass. The experimental method
+consists in a high-resolution technique (ESPRIT algorithm) which allows precise
+estimations of the viscoelastic properties even in frequency domains with high
+modal overlap (high damping or modal density). Experimental loss factors
+estimated from impact hammer excitations on the free-free plates highly
+corresponds with two theoretical estimations. In the first model (Guyader &
+Lesueur, JSV 58(1), 1978) the calculation is based on multilayered plates
+equations and use wave propagation analysis ; in the second one (Laulagnet &
+Guyader, JASA 96(1), 1994) the thickness deformation solving Navier's equations
+is allowed. Results on several plates with several thicknesses of
+thermoplastics are given and compared with the models, demonstrating the
+validity of the approach.",1210.3333v3
+2012-11-02,Damping of mechanical vibrations by free electrons in metallic nanoresonators,"We investigate the effect of free electrons on the quality factor (Q) of a
+metallic nanomechanical resonator in the form of a thin elastic beam. The
+flexural and longitudinal modes of the beam are modeled using thin beam
+elasticity theory, and simple perturbation theory is used to calculate the rate
+at which an externally excited vibration mode decays due to its interaction
+with free electrons. We find that electron-phonon interaction significantly
+affects the Q of longitudinal modes, and may also be of significance to the
+damping of flexural modes in otherwise high-Q beams. The finite geometry of the
+beam is manifested in two important ways. Its finite length breaks translation
+invariance along the beam and introduces an imperfect momentum conservation law
+in place of the exact law. Its finite width imposes a quantization of the
+electronic states that introduces a temperature scale for which there exists a
+crossover from a high-temperature macroscopic regime, where electron-phonon
+damping behaves as if the electrons were in the bulk, to a low-temperature
+mesoscopic regime, where damping is dominated by just a few dissipation
+channels and exhibits sharp non-monotonic changes as parameters are varied.
+This suggests a novel scheme for probing the electronic spectrum of a nanoscale
+device by measuring the Q of its mechanical vibrations.",1211.0450v1
+2013-01-14,Two-qubit mixed states more entangled than pure states: Comparison of the relative entropy of entanglement for a given nonlocality,"Amplitude damping changes entangled pure states into usually less-entangled
+mixed states. We show, however, that even local amplitude damping of one or two
+qubits can result in mixed states more entangled than pure states if one
+compares the relative entropy of entanglement (REE) for a given degree of the
+Bell-Clauser-Horne-Shimony-Holt inequality violation (referred to as
+nonlocality). By applying Monte-Carlo simulations, we find the maximally
+entangled mixed states and show that they are likely to be optimal by checking
+the Karush-Kuhn-Tucker conditions, which generalize the method of Lagrange
+multipliers for this nonlinear optimization problem. We show that the REE for
+mixed states can exceed that of pure states if the nonlocality is in the range
+(0,0.82) and the maximal difference between these REEs is 0.4. A former
+comparison [Phys. Rev. A 78, 052308 (2008)] of the REE for a given negativity
+showed analogous property but the corresponding maximal difference in the REEs
+is one-order smaller (i.e., 0.039) and the negativity range is (0,0.53) only.
+For appropriate comparison, we normalized the nonlocality measure to be equal
+to the standard entanglement measures, including the negativity, for arbitrary
+two-qubit pure states. We also analyze the influence of the phase-damping
+channel on the entanglement of the initially pure states. We show that the
+minimum of the REE for a given nonlocality can be achieved by this channel,
+contrary to the amplitude damping channel.",1301.2969v2
+2013-07-02,The ESO UVES Advanced Data Products Quasar Sample - I. Dataset and New N_HI Measurements of Damped Absorbers,"We present here a dataset of quasars observed with the Ultraviolet Visual
+Echelle Spectrograph (UVES) on the VLT and available in the ESO UVES Advanced
+Data Products archive. The sample is made up of a total of 250 high resolution
+quasar spectra with emission redshifts ranging from 0.191 < z_em <6.311. The
+total UVES exposure time of this dataset is 1560 hours. Thanks to the high
+resolution of UVES spectra, it is possible to unambiguously measure the column
+density of absorbers with damping wings, down to N_HI > 10^{19} cm^{-2}, which
+constitutes the sub-damped Lya absorber (sub-DLA) threshold. Within the
+wavelength coverage of our UVES data, we find 150 damped Lya systems
+(DLAs)/sub-DLAs in the range 1.5 < z_abs < 4.7. Of these 150, 93 are DLAs and
+57 are sub-DLAs. An extensive search in the literature indicates that 6 of
+these DLAs and 13 of these sub-DLAs have their N_HI measured for the first
+time. Among them, 10 are new identifications as DLAs/sub-DLAs. For each of
+these systems, we obtain an accurate measurement of the HI column density and
+the absorber's redshift in the range 1.7 < z_abs < 4.2 by implementing a Voigt
+profile-fitting algorithm. These absorbers are further confirmed thanks to the
+detection of associated metal lines and/or lines from members of the Lyman
+series. In our data, a few quasars' lines-of-sight are rich. An interesting
+example is towards QSO J0133+0400 (z_em = 4.154) with six DLAs and sub-DLAs
+reported.",1307.0678v2
+2013-08-23,Stabilization of second-order evolution equations with time delay,"We consider second-order evolution equations in an abstract setting with
+damping and time delay and give sufficient conditions ensuring exponential
+stability. Our abstract framework is then applied to the wave equation, the
+elasticity system and the Petrovsky system.",1308.5106v1
+2013-09-21,Bottomonium suppression at $\sqrt{s_{NN}}=2.76$ TeV using model based on color screening and gluonic dissociation with collisional damping,"We present a model to explain the bottomonium suppression in Pb+Pb collisions
+at mid rapidity obtained from Large Hadron Collider (LHC) energy,
+$\sqrt{s_{NN}}=2.76$ TeV. The model consists of two decoupled mechanisms
+namely, color screening during bottomonium production followed by gluon induced
+dissociation along with collisional damping. The quasi-particle model (QPM) is
+used as equation of state (EOS) for the Quark-Gluon Plasma (QGP) medium. The
+feed-down from higher $\Upsilon$ states, such as $\Upsilon(1P)$, $\Upsilon(2S)$
+and $\Upsilon(2P)$, dilated formation times for bottomonium states and viscous
+effect of QGP medium are other ingredients included in the current formulation.
+We further assume that the QGP is expanding according to (1+1)-dimensional
+Bjorken's boost invariant scaling law. The net suppression (in terms of $p_T$
+integrated survival probability) for bottomonium states at mid rapidity is
+obtained as a function of centrality and the result is then compared both
+quantitatively and qualitatively with the recent LHC experimental data in the
+mid rapidity region recently published by CMS collaboration. We find that the
+current model, based on the Debye color screening plus gluonic dissociation
+along with collisional damping, better describes the centrality dependence of
+bottomonium suppression at LHC energy as compared to color screening model
+alone.
+  \vskip 0.5cm
+  {\nd \it Keywords} : Color screening, Gluonic dissociation, Collisional
+damping, Survival probability {\nd \it PACS numbers} : 12.38.Mh, 12.38.Gc,
+25.75.Nq, 24.10.Pa",1309.5467v2
+2013-10-20,Nonequilibrium stationary state for a damped rotator,"Perturbative construction of the nonequilibrium steady state of a rotator
+under a stochastic forcing while subject to torque and friction",1310.5379v1
+2013-11-07,Spin-Orbit Torques and Anisotropic Magnetization Damping in Skyrmion Crystals,"The length scale of the magnetization gradients in chiral magnets is
+determined by the relativistic Dzyaloshinskii-Moriya interaction. Thus, even
+conventional spin-transfer torques are controlled by the relativistic
+spin-orbit coupling in these systems, and additional relativistic corrections
+to the current-induced torques and magnetization damping become important for a
+complete understanding of the current-driven magnetization dynamics. We
+theoretically study the effects of reactive and dissipative homogeneous
+spin-orbit torques and anisotropic damping on the current-driven skyrmion
+dynamics in cubic chiral magnets. Our results demonstrate that spin-orbit
+torques play a significant role in the current-induced skyrmion velocity. The
+dissipative spin-orbit torque generates a relativistic Magnus force on the
+skyrmions, whereas the reactive spin-orbit torque yields a correction to both
+the drift velocity along the current direction and the transverse velocity
+associated with the Magnus force. The spin-orbit torque corrections to the
+velocity scale linearly with the skyrmion size, which is inversely proportional
+to the spin-orbit coupling. Consequently, the reactive spin-orbit torque
+correction can be the same order of magnitude as the non-relativistic
+contribution. More importantly, the dissipative spin-orbit torque can be the
+dominant force that causes a deflected motion of the skyrmions if the torque
+exhibits a linear or quadratic relationship with the spin-orbit coupling. In
+addition, we demonstrate that the skyrmion velocity is determined by
+anisotropic magnetization damping parameters governed by the skyrmion size.",1311.1778v1
+2013-11-13,Recent progress in attractors for quintic wave equations,"We report on new results concerning the global well-posedness, dissipativity
+and attractors of the damped quintic wave equations in bounded domains of R^3.",1311.3290v1
+2014-01-19,Analytical Solution of Mathieu Equation,"The general solution of the homogeneous damped Mathieu equation in the
+analytical form, allowing its practical using in many applications, including
+superconductivity studies, without numerical calculations has been found.",1401.5348v1
+2014-06-10,Wigner's Space-time Symmetries based on the Two-by-two Matrices of the Damped Harmonic Oscillators and the Poincaré Sphere,"The second-order differential equation for a damped harmonic oscillator can
+be converted to two coupled first-order equations, with two two-by-two matrices
+leading to the group $Sp(2)$. It is shown that this oscillator system contains
+the essential features of Wigner's little groups dictating the internal
+space-time symmetries of particles in the Lorentz-covariant world. The little
+groups are the subgroups of the Lorentz group whose transformations leave the
+four-momentum of a given particle invariant. It is shown that the damping modes
+of the oscillator correspond to the little groups for massive and
+imaginary-mass particles respectively. When the system makes the transition
+from the oscillation to damping mode, it corresponds to the little group for
+massless particles. Rotations around the momentum leave the four-momentum
+invariant. This degree of freedom extends the $Sp(2)$ symmetry to that of
+$SL(2,c)$ corresponding to the Lorentz group applicable to the four-dimensional
+Minkowski space. The Poincar\'e sphere contains the $SL(2,c)$ symmetry. In
+addition, it has a non-Lorentzian parameter allowing us to reduce the mass
+continuously to zero. It is thus possible to construct the little group for
+massless particles from that of the massive particle by reducing its mass to
+zero. Spin-1/2 particles and spin-1 particles are discussed in detail.",1406.2403v1
+2014-06-11,Quantum critical metals in $4-ε$ dimensions,"We study the quantum theory of a Fermi surface coupled to a gapless boson
+scalar in $D=4-\epsilon$ spacetime dimensions as a simple model for non-Fermi
+liquids (NFL) near a quantum phase transition. Our analysis takes into account
+the full backreaction from Landau damping of the boson, and obtains an RG flow
+that proceeds through three distinct stages. Above the scale of Landau damping
+the Fermi velocity flows to zero, while the coupling evolves according to its
+classical dimension. Once damping becomes important, its backreaction leads to
+a crossover regime where dynamic and static damping effects compete and the
+fermion self-energy does not respect scaling. Below this crossover and having
+tuned the boson to criticality, the theory flows to a $z=3$ scalar interacting
+with a NFL. By increasing the number of bosonic flavors, the phase diagram near
+the quantum critical point interpolates between a superconducting dome fully
+covering the NFL behavior, and a phase where NFL effects become important
+first, before the onset of superconductivity. A generic prediction of the
+theory is that the Fermi velocity and quasiparticle residue vanish with a
+power-law $\omega^\epsilon$ as the fixed point is approached. These features
+may be useful for understanding some of the phenomenology of high $T_c$
+materials in a systematic $\epsilon$--expansion.",1406.3029v2
+2014-10-15,A comparison of weak-turbulence and PIC simulations of weak electron-beam plasma interaction,"Quasilinear theory has long been used to treat the problem of a weak electron
+beam interacting with plasma and generating Langmuir waves. Its extension to
+weak-turbulence theory treats resonant interactions of these Langmuir waves
+with other plasma wave modes, in particular ion-sound waves. These are strongly
+damped in plasma of equal ion and electron temperatures, as sometimes seen in,
+for example, the solar corona and wind. Weak turbulence theory is derived in
+the weak damping limit, with a term describing ion-sound wave damping then
+added. In this paper we use the EPOCH particle-in-cell code to numerically test
+weak turbulence theory for a range of electron-ion temperature ratios. We find
+that in the cold ion limit the results agree well, but increasing ion
+temperature the three-wave resonance becomes broadened in proportion to the
+ion-sound wave damping rate. This may be important in, for example, the theory
+of solar radio bursts, where the spectrum of Langmuir waves is critical.
+Additionally we establish lower limits on the number of simulation particles
+needed to accurately reproduce the electron and wave distributions in their
+saturated states, and to reproduce their intermediate states and time
+evolution.",1410.4046v2
+2015-05-07,Theory for Bose-Einstein condensation of light in nano-fabricated semiconductor microcavities,"We construct a theory for Bose-Einstein condensation of light in
+nano-fabricated semiconductor microcavities. We model the semiconductor by one
+conduction and one valence band which consist of electrons and holes that
+interact via a Coulomb interaction. Moreover, we incorporate screening effects
+by using a contact interaction with the scattering length for a Yukawa
+potential and describe in this manner the crossover from exciton gas to
+electron-hole plasma as we increase the excitation level of the semiconductor.
+We then show that the dynamics of the light in the microcavities is damped due
+to the coupling to the semiconductor. Furthermore, we demonstrate that on the
+electron-hole plasma side of the crossover, which is relevant for the
+Bose-Einstein condensation of light, this damping can be described by a single
+dimensionless damping parameter that depends on the external pumping.
+Hereafter, we propose to probe the superfluidity of light in these
+nano-fabricated semiconductor microcavities by making use of the differences in
+the response in the normal or superfluid phase to a sudden rotation of the
+trap. In particular, we determine frequencies and damping of the scissors modes
+that are excited in this manner. Moreover, we show that a distinct signature of
+the dynamical Casimir effect can be observed in the density-density
+correlations of the excited light fluid.",1505.01732v2
+2015-08-21,Which verification qubits perform best for secure communication in noisy channel?,"In secure quantum communication protocols, a set of single qubits prepared
+using 2 or more mutually unbiased bases or a set of $n$-qubit ($n\geq2$)
+entangled states of a particular form are usually used to form a verification
+string which is subsequently used to detect traces of eavesdropping. The qubits
+that form a verification string are referred to as decoy qubits, and there
+exists a large set of different quantum states that can be used as decoy
+qubits. In the absence of noise, any choice of decoy qubits provides equivalent
+security. In this paper, we examine such equivalence for noisy environment
+(e.g., in amplitude damping, phase damping, collective dephasing and collective
+rotation noise channels) by comparing the decoy-qubit assisted schemes of
+secure quantum communication that use single qubit states as decoy qubits with
+the schemes that use entangled states as decoy qubits. Our study reveals that
+the single qubit assisted scheme perform better in some noisy environments,
+while some entangled qubits assisted schemes perform better in other noisy
+environments. Specifically, single qubits assisted schemes perform better in
+amplitude damping and phase damping noisy channels, whereas a few
+Bell-state-based decoy schemes are found to perform better in the presence of
+the collective noise. Thus, if the kind of noise present in a communication
+channel (i.e., the characteristics of the channel) is known or measured, then
+the present study can provide the best choice of decoy qubits required for
+implementation of schemes of secure quantum communication through that channel.",1508.05237v1
+2015-08-30,Spin-transfer torque based damping control of parametrically excited spin waves in a magnetic insulator,"The damping of spin waves parametrically excited in the magnetic insulator
+Yttrium Iron Garnet (YIG) is controlled by a dc current passed through an
+adjacent normal-metal film. The experiment is performed on a macroscopically
+sized YIG(100nm)/Pt(10nm) bilayer of 4x2 mm^2 lateral dimensions. The spin-wave
+relaxation frequency is determined via the threshold of the parametric
+instability measured by Brillouin light scattering (BLS) spectroscopy. The
+application of a dc current to the Pt film leads to the formation of a
+spin-polarized electron current normal to the film plane due to the spin Hall
+effect (SHE). This spin current exerts a spin transfer torque (STT) in the YIG
+film and, thus, changes the spin-wave damping. Depending on the polarity of the
+applied dc current with respect to the magnetization direction, the damping can
+be increased or decreased. The magnitude of its variation is proportional to
+the applied current. A variation in the relaxation frequency of +/-7.5% is
+achieved for an applied dc current density of 5*10^10 A/m^2.",1508.07517v1
+2015-09-08,Model comparison for the density structure across solar coronal waveguides,"The spatial variation of physical quantities, such as the mass density,
+across solar atmospheric waveguides governs the timescales and spatial scales
+for wave damping and energy dissipation. The direct measurement of the spatial
+distribution of density, however, is difficult and indirect seismology
+inversion methods have been suggested as an alternative. We applied Bayesian
+inference, model comparison, and model-averaging techniques to the inference of
+the cross-field density structuring in solar magnetic waveguides using
+information on periods and damping times for resonantly damped
+magnetohydrodynamic (MHD) transverse kink oscillations. Three commonly employed
+alternative profiles were used to model the variation of the mass density
+across the waveguide boundary. Parameter inference enabled us to obtain
+information on physical quantities such as the Alfv\'en travel time, the
+density contrast, and the transverse inhomogeneity length scale. The inference
+results from alternative density models were compared and their differences
+quantified. Then, the relative plausibility of the considered models was
+assessed by performing model comparison. Our results indicate that the evidence
+in favor of any of the three models is minimal, unless the oscillations are
+strongly damped. In such a circumstance, the application of model-averaging
+techniques enables the computation of an evidence-weighted inference that takes
+into account the plausibility of each model in the calculation of a combined
+inversion for the unknown physical parameters.",1509.02340v1
+2015-09-15,Resonance vibration of impact oscillator with biharmonic excitation,"We consider a damped impact oscillator subject to the action of a biharmonic
+force. The conditions for the existence and stability of almost periodic
+resonance solutions are investigated.",1509.05381v1
+2015-11-08,On 2d incompressible Euler equations with partial damping,"We consider various questions about the 2d incompressible Navier-Stokes and
+Euler equations on a torus when dissipation is removed from or added to some of
+the Fourier modes.",1511.02530v1
+2015-12-11,The Ping Pong Pendulum,"Many damped mechanical systems oscillate with increasing frequency as the
+amplitude decreases. One popular example is Euler's Disk, where the point of
+contact rotates with increasing rapidity as the energy is dissipated. We study
+a simple mechanical pendulum that exhibits this behaviour.",1512.03700v1
+2016-01-26,Fast convex optimization via inertial dynamics with Hessian driven damping,"We first study the fast minimization properties of the trajectories of the
+second-order evolution equation $$\ddot{x}(t) + \frac{\alpha}{t} \dot{x}(t) +
+\beta \nabla^2 \Phi (x(t))\dot{x} (t) + \nabla \Phi (x(t)) = 0,$$ where
+$\Phi:\mathcal H\to\mathbb R$ is a smooth convex function acting on a real
+Hilbert space $\mathcal H$, and $\alpha$, $\beta$ are positive parameters. This
+inertial system combines an isotropic viscous damping which vanishes
+asymptotically, and a geometrical Hessian driven damping, which makes it
+naturally related to Newton's and Levenberg-Marquardt methods. For $\alpha\geq
+3$, $\beta >0$, along any trajectory, fast convergence of the values
+$$\Phi(x(t))- \min_{\mathcal H}\Phi =\mathcal O\left(t^{-2}\right)$$ is
+obtained, together with rapid convergence of the gradients $\nabla\Phi(x(t))$
+to zero. For $\alpha>3$, just assuming that $\Phi$ has minimizers, we show that
+any trajectory converges weakly to a minimizer of $\Phi$, and $
+\Phi(x(t))-\min_{\mathcal H}\Phi = o(t^{-2})$. Strong convergence is
+established in various practical situations. For the strongly convex case,
+convergence can be arbitrarily fast depending on the choice of $\alpha$. More
+precisely, we have $\Phi(x(t))- \min_{\mathcal H}\Phi = \mathcal
+O(t^{-\frac{2}{3}\alpha})$. We extend the results to the case of a general
+proper lower-semicontinuous convex function $\Phi : \mathcal H \rightarrow
+\mathbb R \cup \{+\infty \}$. This is based on the fact that the inertial
+dynamic with Hessian driven damping can be written as a first-order system in
+time and space. By explicit-implicit time discretization, this opens a gate to
+new $-$ possibly more rapid $-$ inertial algorithms, expanding the field of
+FISTA methods for convex structured optimization problems.",1601.07113v1
+2016-03-28,Stabilization of gravity water waves,"This paper is devoted to the stabilization of the incompressible Euler
+equation with free surface. We study the damping of two-dimensional gravity
+waves by an absorbing beach where the water-wave energy is dissipated by using
+the variations of the external pressure.",1603.08541v1
+2016-06-14,Precession Relaxation of Viscoelastic Oblate Rotators,"Perturbations of all sorts destabilise the rotation of a small body and leave
+it in a non-principal spin state. In such a state, the body experiences
+alternating stresses generated by the inertial forces. This yields nutation
+relaxation, i.e., evolution of the spin towards the principal rotation about
+the maximal-inertia axis. Knowledge of the timescales needed to damp the
+nutation is crucial in studies of small bodies' dynamics. In the literature
+hitherto, nutation relaxation has always been described with aid of an
+empirical quality factor $\,Q\,$ introduced to parameterise the energy
+dissipation rate.
+  Among the drawbacks of this approach was its inability to describe the
+dependence of the relaxation rate upon the current nutation angle. This
+inability stemmed from our lack of knowledge of the quality factor's dependence
+on the forcing frequency. In this article, we derive our description of
+nutation damping directly from the rheological law obeyed by the material. This
+renders us the nutation damping rate as a function of the current nutation
+angle, as well as of the shape and the rheological parameters of the body. In
+contradistinction from the approach based on an empirical $\,Q\,$-factor, our
+development gives a zero damping rate in the spherical-shape limit. Our method
+is generic and applicable to any shape and to any linear rheological law.
+However, to simplify the developments, here we consider a dynamically oblate
+rotator with a Maxwell rheology.",1606.04559v3
+2016-09-07,Quasi-stability and Exponential Attractors for A Non-Gradient System---Applications to Piston-Theoretic Plates with Internal Damping,"We consider a nonlinear (Berger or Von Karman) clamped plate model with a
+{\em piston-theoretic} right hand side---which include non-dissipative,
+non-conservative lower order terms. The model arises in aeroelasticity when a
+panel is immersed in a high velocity linear potential flow; in this case the
+effect of the flow can be captured by a dynamic pressure term written in terms
+of the material derivative of the plate's displacement. The effect of
+fully-supported internal damping is studied for both Berger and von Karman
+dynamics. The non-dissipative nature of the dynamics preclude the use of strong
+tools such as backward-in-time smallness of velocities and finiteness of the
+dissipation integral. Modern quasi-stability techniques are utilized to show
+the existence of compact global attractors and generalized fractal exponential
+attractors. Specific results depending on the size of the damping parameter and
+the nonlinearity in force. For the Berger plate, in the presence of large
+damping, the existence of a proper global attractor (whose fractal dimension is
+finite in the state space) is shown via a decomposition of the nonlinear
+dynamics. This leads to the construction of a compact set upon which
+quasi-stability theory can be implemented. Numerical investigations for
+appropriate 1-D models are presented which explore and support the abstract
+results presented herein.",1609.02211v1
+2016-10-26,On the region of attraction of phase-locked states for swing equations on connected graphs with inhomogeneous dampings,"We consider the synchronization problem of swing equations, a second-order
+Kuramoto-type model, on connected networks with inhomogeneous dampings. This
+was largely motivated by its relevance to the dynamics of power grids. We focus
+on the estimate of the region of attraction of synchronous states which is a
+central problem in the transient stability of power grids. In the recent
+literature, D\""{o}rfler, Chertkov, and Bullo [Proc. Natl. Acad. Sci. USA, 110
+(2013), pp. 2005-2010] found a condition for the synchronization in smart
+grids. They pointed out that the region of attraction is an important unsolved
+problem. In [SIAM J. Control Optim., 52 (2014), pp. 2482-2511], only a special
+case was considered where the oscillators have homogeneous dampings and the
+underlying graph has a diameter less than or equal to 2. There the analysis
+heavily relies on these assumptions; however, they are too strict compared to
+the real power networks. In this paper, we continue the study and derive an
+estimate on the region of attraction of phase-locked states for lossless power
+grids on connected graphs with inhomogeneous dampings. Our main strategy is
+based on the gradient-like formulation and energy estimate. We refine the
+assumptions by constructing a new energy functional which enables us to
+consider such general settings.",1610.08437v1
+2016-10-31,A quest for new physics inside the neutron,"The lecture presents an overview of the quest for the new physics in low
+energy neutron phenomena. In addition to the traditional topics the quantum
+damping of $n$ $\bar{n}$ oscillations is discussed.",1610.10046v1
+2016-11-28,First Demonstration of Electrostatic Damping of Parametric Instability at Advanced LIGO,"Interferometric gravitational wave detectors operate with high optical power
+in their arms in order to achieve high shot-noise limited strain sensitivity. A
+significant limitation to increasing the optical power is the phenomenon of
+three-mode parametric instabilities, in which the laser field in the arm
+cavities is scattered into higher order optical modes by acoustic modes of the
+cavity mirrors. The optical modes can further drive the acoustic modes via
+radiation pressure, potentially producing an exponential buildup. One proposed
+technique to stabilize parametric instability is active damping of acoustic
+modes. We report here the first demonstration of damping a parametrically
+unstable mode using active feedback forces on the cavity mirror. A 15,538 Hz
+mode that grew exponentially with a time constant of 182 sec was damped using
+electro-static actuation, with a resulting decay time constant of 23 sec. An
+average control force of 0.03 nNrms was required to maintain the acoustic mode
+at its minimum amplitude.",1611.08997v1
+2016-12-19,Improving the efficiency of joint remote state preparation in noisy environment with weak measurement,"Quantum secure communication provides a new way for protecting the security
+of information. As an important component of quantum secure communication,
+remote state preparation (RSP) can securely transmit a quantum state from a
+sender to a remote receiver. The existence of quantum noise severely affects
+the security and reliability of quantum communication system. In this paper, we
+study the method for improving the efficiency of joint RSP (JRSP) subjected to
+noise with the help of weak measurement and its reversal measurement. Taking a
+GHZ based deterministic JRSP as an example, we utilize the technique of weak
+measurement and its reversal to suppress the effect of the amplitude-damping
+noise firstly. Our study shows that the fidelity of the output state can be
+improved in the amplitude-damping noise. We also study the effect of weak
+measurement and its reversal in other three types of noise usually encountered
+in real-world, namely, the bit-flip, phase-flip (phase-damping) and
+depolarizing noise. Our results show that the weak measurement has no effect
+for suppressing the bit-flip and phase-flip (phase-damping) noise, while has
+slight effect for suppressing the depolarizing noise. Our study is suitable for
+JRSP and RSP, and will be helpful for improving the efficiency of multiparticle
+entanglement based quantum secure communication in real implementation.",1612.06020v1
+2017-03-21,Evidence for structural damping in a high-stress silicon nitride nanobeam and its implications for quantum optomechanics,"We resolve the thermal motion of a high-stress silicon nitride nanobeam at
+frequencies far below its fundamental flexural resonance (3.4 MHz) using
+cavity-enhanced optical interferometry. Over two decades, the displacement
+spectrum is well-modeled by that of a damped harmonic oscillator driven by a
+$1/f$ thermal force, suggesting that the loss angle of the beam material is
+frequency-independent. The inferred loss angle at 3.4 MHz, $\phi = 4.5\cdot
+10^{-6}$, agrees well with the quality factor ($Q$) of the fundamental beam
+mode ($\phi = Q^{-1}$). In conjunction with $Q$ measurements made on higher
+order flexural modes, and accounting for the mode dependence of stress-induced
+loss dilution, we find that the intrinsic (undiluted) loss angle of the beam
+changes by less than a factor of 2 between 50 kHz and 50 MHz. We discuss the
+impact of such ""structural damping"" on experiments in quantum optomechanics, in
+which the thermal force acting on a mechanical oscillator coupled to an optical
+cavity is overwhelmed by radiation pressure shot noise. As an illustration, we
+show that structural damping reduces the bandwidth of ponderomotive squeezing.",1703.07134v2
+2017-03-29,"Comment on ""Spreading widths of giant resonances in spherical nuclei: damped transient response"" by Severyukhin et al. [arXiv:1703.05710]","We argue whether physics of universal approach of Severyukhin et al.
+[arXiv:1703.05710] is approved.",1703.10003v1
+2017-05-16,Propagation of transition fronts in nonlinear chains with non-degenerate on-site potentials,"We address the problem of a front propagation in chains with a bi-stable
+nondegenerate on-site potential and a nonlinear gradient coupling. For a
+generic nonlinear coupling, one encounters a special regime of transitions,
+characterized by extremely narrow fronts, far supersonic velocities of
+propagation and long waves in the oscillatory tail. This regime can be
+qualitatively associated with a shock wave. The front propagation can be
+described with the help of a simple reduced-order model; the latter delivers a
+kinetic law, which is almost not sensitive to fine details of the on-site
+potential. Besides, it is possible to predict all main characteristics of the
+transition front, including its shape and frequency and amplitude of the
+oscillatory tail. The numerical results are in a good agreement with the
+analytical predictions. The suggested approach allows one to consider the
+effects of an external pre-load and on-site damping. When the damping is
+moderate, the analysis remains in the frame of the reduced-order model. It is
+possible to consider the solution for the front propagating in the damped chain
+as a perturbation of the undamped dynamics. This approach yield reasonable
+predictions. When the damping is high, the transition front enters a completely
+different asymptotic regime. The gradient nonlinearity generically turns
+negligible, and the propagating front converges to the exact solution obtained
+from a simple linear continuous model.",1705.05555v1
+2017-08-16,The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere,"High spatial and temporal resolution images of a sunspot, obtained
+simultaneously in multiple optical and UV wavelengths, are employed to study
+the propagation and damping characteristics of slow magnetoacoustic waves up to
+transition region heights. Power spectra are generated from intensity
+oscillations in sunspot umbra, across multiple atmospheric heights, for
+frequencies up to a few hundred mHz. It is observed that the power spectra
+display a power-law dependence over the entire frequency range, with a
+significant enhancement around 5.5 mHz found for the chromospheric channels.
+The phase-difference spectra reveal a cutoff frequency near 3 mHz, up to which
+the oscillations are evanescent, while those with higher frequencies propagate
+upwards. The power-law index appears to increase with atmospheric height. Also,
+shorter damping lengths are observed for oscillations with higher frequencies
+suggesting frequency-dependent damping. Using the relative amplitudes of the
+5.5 mHz (3 minute) oscillations, we estimate the energy flux at different
+heights, which seems to decay gradually from the photosphere, in agreement with
+recent numerical simulations. Furthermore, a comparison of power spectra across
+the umbral radius highlights an enhancement of high-frequency waves near the
+umbral center, which does not seem to be related to magnetic field inclination
+angle effects.",1708.04835v1
+2017-08-29,Spin wave damping arising from phase coexistence below $T_c$ in colossal magnetoresistive La$_{0.7}$Ca$_{0.3}$MnO$_3$,"While the spin dynamics of La$_{0.7}$Ca$_{0.3}$MnO$_3$ in the ferromagnetic
+phase are known to be unconventional, previous measurements have yielded
+contradictory results regarding the damping of spin wave excitations. Neutron
+spectroscopy measurements on a sample with a transition temperature of
+$T_c$=257 K, higher than most single crystals, unambiguously reveal an
+anomalous increase in spin wave damping for excitations approaching the
+Brillouin zone boundary along the [$100$] direction that cannot be explained as
+an artifact due to a noninteracting phonon branch. Spin waves throughout the
+($HK0$) plane display a common trend where the spin wave damping is dependent
+upon the excitation energy, increasing for energies above roughly 15 meV and
+reaching a full width at half maximum of at least 20 meV. The results are
+consistent with a model of intrinsic spatial inhomogeneity with phase separated
+regions approximately 18 {\AA} in size persisting over a large range of
+temperatures below $T_c$.",1708.08960v2
+2017-09-08,Topological and Graph-coloring Conditions on the Parameter-independent Stability of Second-order Networked Systems,"In this paper, we study parameter-independent stability in qualitatively
+heterogeneous passive networked systems containing damped and undamped nodes.
+Given the graph topology and a set of damped nodes, we ask if output consensus
+is achieved for all system parameter values. For given parameter values, an
+eigenspace analysis is used to determine output consensus. The extension to
+parameter-independent stability is characterized by a coloring problem, named
+the richly balanced coloring (RBC) problem. The RBC problem asks if all nodes
+of the graph can be colored red, blue and black in such a way that (i) every
+damped node is black, (ii) every black node has blue neighbors if and only if
+it has red neighbors, and (iii) not all nodes in the graph are black. Such a
+colored graph is referred to as a richly balanced colored graph.
+Parameter-independent stability is guaranteed if there does not exist a richly
+balanced coloring. The RBC problem is shown to cover another well-known graph
+coloring scheme known as zero forcing sets. That is, if the damped nodes form a
+zero forcing set in the graph, then a richly balanced coloring does not exist
+and thus, parameter-independent stability is guaranteed. However, the full
+equivalence of zero forcing sets and parameter-independent stability holds only
+true for tree graphs. For more general graphs with few fundamental cycles an
+algorithm, named chord node coloring, is proposed that significantly
+outperforms a brute-force search for solving the NP-complete RBC problem.",1709.02629v1
+2017-10-11,Collisional damping rates for plasma waves,"The distinction between the plasma dynamics dominated by collisional
+transport versus collective processes has never been rigorously addressed until
+recently. A recent paper [Yoon et al., Phys. Rev. E 93, 033203 (2016)]
+formulates for the first time, a unified kinetic theory in which collective
+processes and collisional dynamics are systematically incorporated from first
+principles. One of the outcomes of such a formalism is the rigorous derivation
+of collisional damping rates for Langmuir and ion-acoustic waves, which can be
+contrasted to the heuristic customary approach. However, the results are given
+only in formal mathematical expressions. The present Brief Communication
+numerically evaluates the rigorous collisional damping rates by considering the
+case of plasma particles with Maxwellian velocity distribution function so as
+to assess the consequence of the rigorous formalism in a quantitative manner.
+Comparison with the heuristic (""Spitzer"") formula shows that the accurate
+damping rates are much lower in magnitude than the conventional expression,
+which implies that the traditional approach over-estimates the importance of
+attenuation of plasma waves by collisional relaxation process. Such a finding
+may have a wide applicability ranging from laboratory to space and
+astrophysical plasmas.",1710.03874v1
+2017-10-20,Tidal dissipation in rotating fluid bodies: the presence of a magnetic field,"We investigate effects of the presence of a magnetic field on tidal
+dissipation in rotating fluid bodies. We consider a simplified model consisting
+of a rigid core and a fluid envelope, permeated by a background magnetic field
+(either a dipolar field or a uniform axial field). The wavelike tidal responses
+in the fluid layer are in the form of magnetic-Coriolis waves, which are
+restored by both the Coriolis force and the Lorentz force. Energy dissipation
+occurs through viscous damping and Ohmic damping of these waves. Our numerical
+results show that the tidal dissipation can be dominated by Ohmic damping even
+with a weak magnetic field. The presence of a magnetic field smooths out the
+complicated frequency-dependence of the dissipation rate, and broadens the
+frequency spectrum of the dissipation rate, depending on the strength of the
+background magnetic field. However, the frequency-averaged dissipation is
+independent of the strength and structure of the magnetic field, and of the
+dissipative parameters, in the approximation that the wave-like response is
+driven only by the Coriolis force acting on the non-wavelike tidal flow.
+Indeed, the frequency-averaged dissipation quantity is in good agreement with
+previous analytical results in the absence of magnetic fields. Our results
+suggest that the frequency-averaged tidal dissipation of the wavelike
+perturbations is insensitive to detailed damping mechanisms and dissipative
+properties.",1710.07690v2
+2017-11-30,"Implications of dark matter cascade decay from DAMPE, HESS, Fermi-LAT and AMS02 data","Recent high-energy cosmic $e^\pm$ measurement from the DArk Matter Particle
+Explorer (DAMPE) satellite confirms the deviation of total cosmic ray electron
+spectrum above 700-900 GeV from a simple power law. In this paper we
+demonstrate that the cascade decay of dark matter (DM) can account for DAMPE's
+TeV $e^+e^-$ spectrum. We select the least constraint DM decay channel into
+four muons as the benchmark scenario, and perform an analysis with propagation
+variance in both DM signal and the Milky Way's electron background. The
+best-fit of the model is obtained for joint DAMPE, Fermi-Large Area Telescope
+(Fermi-LAT), High Energy Stereoscopic System (HESS), high energy electron data
+sets, and with an $\mathcal{O}(10^{26})$ second decay lifetime, which is
+consistent with existing gamma ray and cosmic microwave background limits. We
+compare the spectral difference between the cascade decay of typical
+final-state channels. The least constrained $4\mu$ channels give good fits to
+the electron spectrum's TeV scale down-turn, yet their low energy spectrum has
+tension with sub-TeV positron data from AMS02. We also consider a three-step
+cascade decay into eight muons, and also a gamma-ray constrained $4\mu,4b$
+mixed channel, to demonstrate that a further softened cascade decay signal
+would be required for the agreement with all the data sets.",1712.00370v3
+2017-12-04,"Scalar dark matter, Type II Seesaw and the DAMPE cosmic ray $e^+ + e^-$ excess","The DArk Matter Particle Explorer (DAMPE) has reported a measurement of the
+flux of high energy cosmic ray electrons plus positrons (CREs) in the energy
+range between $25$ GeV and $4.6$ TeV. With unprecedented high energy
+resolution, the DAMPE data exhibit an excess of the CREs flux at an energy of
+around $1.4$ TeV. In this letter, we discuss how the observed excess can be
+understood in a minimal framework where the Standard Model (SM) is supplemented
+by a stable SM singlet scalar as dark matter (DM) and type II seesaw for
+generating the neutrino mass matrix. In our framework, a pair of DM particles
+annihilates into a pair of the SM SU(2) triplet scalars ($\Delta$s) in type II
+seesaw, and the subsequent $\Delta$ decays create the primary source of the
+excessive CREs around $1.4$ TeV. The lepton flavor structure of the primary
+source of CREs has a direct relationship with the neutrino oscillation data. We
+find that the DM interpretation of the DAMPE excess determines the pattern of
+neutrino mass spectrum to be the inverted hierarchy type, taking into account
+the constraints from the Fermi-LAT observations of dwarf spheroidal galaxies.",1712.00869v2
+2017-12-07,Nonlinear growth of structure in cosmologies with damped matter fluctuations,"We investigate the nonlinear evolution of structure in variants of the
+standard cosmological model which display damped density fluctuations relative
+to cold dark matter (e.g. in which cold dark matter is replaced by warm or
+interacting DM). Using N-body simulations, we address the question of how much
+information is retained from different scales in the initial linear power
+spectrum following the nonlinear growth of structure. We run a suite of N-body
+simulations with different initial linear matter power spectra to show that,
+once the system undergoes nonlinear evolution, the shape of the linear power
+spectrum at high wavenumbers does not affect the non-linear power spectrum,
+while it still matters for the halo mass function. Indeed, we find that linear
+power spectra which differ from one another only at wavenumbers larger than
+their half-mode wavenumber give rise to (almost) identical nonlinear power
+spectra at late times, regardless of the fact that they originate from
+different models with damped fluctuations. On the other hand, the halo mass
+function is more sensitive to the form of the linear power spectrum. Exploiting
+this result, we propose a two parameter model of the transfer function in
+generic damped scenarios, and show that this parametrisation works as well as
+the standard three parameter models for the scales on which the linear spectrum
+is relevant.",1712.02742v2
+2017-12-11,DAMPE excess from decaying right-handed neutrino dark matter,"The flux of high-energy cosmic-ray electrons plus positrons recently measured
+by the DArk Matter Particle Explorer (DAMPE) exhibits a tentative peak excess
+at an energy of around $1.4$ TeV. In this paper, we consider the minimal gauged
+$U(1)_{B-L}$ model with a right-handed neutrino (RHN) dark matter (DM) and
+interpret the DAMPE peak with a late-time decay of the RHN DM into $e^\pm
+W^\mp$. We find that a DM lifetime $\tau_{DM} \sim 10^{28}$ s can fit the DAMPE
+peak with a DM mass $m_{DM}=3$ TeV. This favored lifetime is close to the
+current bound on it by Fermi-LAT, our decaying RHN DM can be tested once the
+measurement of cosmic gamma ray flux is improved. The RHN DM communicates with
+the Standard Model particles through the $U(1)_{B-L}$ gauge boson ($Z^\prime$
+boson), and its thermal relic abundance is controlled by only three free
+parameters: $m_{DM}$, the $U(1)_{B-L}$ gauge coupling ($\alpha_{BL}$), and the
+$Z^\prime$ boson mass ($m_{Z^\prime}$). For $m_{DM}=3$ TeV, the rest of the
+parameters are restricted to be $m_{Z^\prime}\simeq 6$ TeV and $0.00807 \leq
+\alpha_{BL} \leq 0.0149$, in order to reproduce the observed DM relic density
+and to avoid the Landau pole for the running $\alpha_{BL}$ below the Planck
+scale. This allowed region will be tested by the search for a $Z^\prime$ boson
+resonance at the future Large Hadron Collider.",1712.03652v3
+2017-12-11,A Statistical Study on The Frequency-Dependent Damping of Slow-mode Waves in Polar Plumes and Interplumes,"We perform a statistical study on the frequency-dependent damping of slow
+waves propagating along polar plumes and interplumes in the solar corona.
+Analysis of a large sample of extreme ultraviolet (EUV) imaging data with high
+spatial and temporal resolutions obtained from AIA/SDO suggests an inverse
+power-law dependence of the damping length on the periodicity of slow waves
+(i.e., the shorter period oscillations exhibit longer damping lengths), in
+agreement with the previous case studies. Similar behavior is observed in both
+plume and interplume regions studied in AIA 171 \AA\ and AIA 193 \AA\
+passbands. It is found that the short-period (2--6 min) waves are relatively
+more abundant than their long period (7--30 min) counterparts in contrast to
+the general belief that the polar regions are dominated by the longer-period
+slow waves. We also derived the slope of the power spectra ($\mathrm{\alpha}$,
+the power-law index) statistically to better understand the characteristics of
+turbulence present in the region. It is found that the $\mathrm{\alpha}$ values
+and their distributions are similar in both plume and interplume structures
+across the two AIA passbands. At the same time, the spread of these
+distributions also indicates the complexity of the underlying turbulence
+mechanism.",1712.03673v1
+2018-08-05,"Dispersion, damping, and intensity of spin excitations in the single-layer (Bi,Pb)$_{2}$(Sr,La)$_{2}$CuO$_{6+δ}$ cuprate superconductor family","Using Cu-$L_3$ edge resonant inelastic x-ray scattering (RIXS) we measured
+the dispersion and damping of spin excitations (magnons and paramagnons) in the
+high-$T_\mathrm{c}$ superconductor (Bi,Pb)$_{2}$(Sr,La)$_{2}$CuO$_{6+\delta}$
+(Bi2201), for a large doping range across the phase diagram ($0.03\lesssim
+p\lesssim0.21$). Selected measurements with full polarization analysis
+unambiguously demonstrate the spin-flip character of these excitations, even in
+the overdoped sample. We find that the undamped frequencies increase slightly
+with doping for all accessible momenta, while the damping grows rapidly, faster
+in the (0,0)$\rightarrow$(0.5,0.5) nodal direction than in the
+(0,0)$\rightarrow$(0.5,0) antinodal direction. We compare the experimental
+results to numerically exact determinant quantum Monte Carlo (DQMC)
+calculations that provide the spin dynamical structure factor
+$S(\textbf{Q},\omega)$ of the three-band Hubbard model. The theory reproduces
+well the momentum and doping dependence of the dispersions and spectral weights
+of magnetic excitations. These results provide compelling evidence that
+paramagnons, although increasingly damped, persist across the superconducting
+dome of the cuprate phase diagram; this implies that long range
+antiferromagnetic correlations are quickly washed away, while short range
+magnetic interactions are little affected by doping.",1808.01682v1
+2018-10-16,Dark matter gets DAMPE,"The DArk Matter Particle Explorer (DAMPE) recently reported an excess of
+electrons/positrons above expected background fluxes even when a double
+power-law background spectrum is assumed. Several dark matter models that
+involve TeV-scale leptophilic WIMPs have been suggested in the literature to
+account for this excess. All of these models are associated with the presence
+of a nearby dark matter clump/over-density.
+  In this work we set out to explore how current constraints from observational
+data impact the suggested parameter space for a dark matter explanation of the
+DAMPE excess, as well as make projections of the capacity of LOFAR and the
+up-coming SKA to observe indirect radio emissions from the nearby dark matter
+over-density.
+  We show that LOFAR is incapable of probing the parameter space for DAMPE
+excess models, unless the dark matter clump is in the form of an ultra-compact
+mini halo. Fermi-LAT limits on dark matter annihilation are unable to probe
+these models in all cases. Limits derived from diffuse Coma cluster radio
+emission can probe a substantial portion of the parameter space and muon
+neutrino limits inferred from galactic centre gamma-ray fluxes heavily restrict
+muon coupling for the proposed WIMPs. The SKA is shown to able to fully probe
+the parameter space of all the studied models using indirect emissions from the
+local dark matter over-density.",1810.07176v2
+2018-11-15,Damping rate of a fermion in ultradegenerate chiral matter,"We compute the damping rate of a fermion propagating in a chiral plasma when
+there is an imbalance between the densities of left- and right-handed fermions,
+after generalizing the hard thermal loop resummation techniques for these
+systems. In the ultradegenerate limit, for very high energies the damping rate
+of this external fermion approaches a constant value. Closer to the two Fermi
+surfaces, however, we find that the rate depends on both the energy and the
+chirality of the fermion, being higher for the predominant chirality. This
+comes out as a result of its scattering with the particles of the plasma,
+mediated by the exchange of Landau damped photons. In particular, we find that
+the chiral imbalance is responsible for a different propagation of the left and
+right circular polarised transverse modes of the photon, and that a chiral
+fermion interacts differently with these two transverse modes. We argue that
+spontaneous radiation of energetic fermions is kinematically forbidden, and
+discuss the time regime where our computation is valid.",1811.06394v3
+2018-12-16,Nonlinear Dynamics of Spherical Shells Buckling under Step Pressure,"Dynamic buckling is addressed for complete elastic spherical shells subject
+to a rapidly applied step in external pressure. Insights from the perspective
+of nonlinear dynamics reveal essential mathematical features of the buckling
+phenomena. To capture the strong buckling imperfection-sensitivity, initial
+geometric imperfections in the form of an axisymmetric dimple at each pole are
+introduced. Dynamic buckling under the step pressure is related to the
+quasi-static buckling pressure. Both loadings produce catastrophic collapse of
+the shell for conditions in which the pressure is prescribed. Damping plays an
+important role in dynamic buckling because of the time-dependent nonlinear
+interaction among modes, particularly the interaction between the spherically
+symmetric 'breathing' mode and the buckling mode. In this paper we argue that
+the precise frequency dependence of the damping does not matter as most of the
+damping happens at a single frequency (the breathing frequency). In general,
+there is not a unique step pressure threshold separating responses associated
+with buckling from those that do not buckle. Instead there exists a cascade of
+buckling thresholds, dependent on the damping and level of imperfection,
+separating pressures for which buckling occurs from those for which it does not
+occur. For shells with small and moderately small imperfections the dynamic
+step buckling pressure can be substantially below the quasi-static buckling
+pressure.",1812.06526v2
+2019-01-09,Turbulent dynamo in a weakly ionized medium,"The small-scale turbulent dynamo is an important process contributing to the
+cosmic magnetization. In partially ionized astrophysical plasmas, the dynamo
+growth of magnetic energy strongly depends on the coupling state between ions
+and neutrals and the ion-neutral collisional damping effect. A new damping
+stage of turbulent dynamo in a weakly ionized medium was theoretically
+predicted by Xu \& Lazarian (2016). By carrying out a 3D two-fluid dynamo
+simulation, here we for the first time numerically confirmed the physical
+conditions and the linear-in-time growth of magnetic field strength of the
+damping stage of dynamo. The dynamo-amplified magnetic field has a
+characteristic length as the damping scale, which increases with time and can
+reach the injection scale of turbulence after around eight largest
+eddy-turnover times given sufficiently low ionization fraction and weak initial
+magnetic field. Due to the weak coupling between ions and neutrals, most
+turbulent energy carried by neutrals cannot be converted to the magnetic
+energy, resulting in a relatively weak magnetic field at the end of dynamo.
+This result has important implications for the growth of magnetic fields in the
+partially ionized interstellar medium and shock acceleration of Galactic cosmic
+rays.",1901.02893v1
+2019-01-25,Quantum speed limit time for correlated quantum channel,"Memory effects play a fundamental role in the dynamics of open quantum
+systems. There exist two different views on memory for quantum noises. In the
+first view, the quantum channel has memory when there exist correlations
+between successive uses of the channels on a sequence of quantum systems. These
+types of channels are also known as correlated quantum channels. In the second
+view, memory effects result from correlations which are created during the
+quantum evolution. In this work we will consider the first view and study the
+quantum speed limit time for a correlated quantum channel. Quantum speed limit
+time is the bound on the minimal time which is needed for a quantum system to
+evolve from an initial state to desired states. The quantum evolution is fast
+if the quantum speed limit time is short. In this work, we will study the
+quantum speed limit time for some correlated unital and correlated non-unital
+channels. As an example for unital channels we choose correlated dephasing
+colored noise. We also consider the correlated amplitude damping and correlated
+squeezed generalized amplitude damping channels as the examples for non-unital
+channels. It will be shown that the quantum speed limit time for correlated
+pure dephasing colored noise is increased by increasing correlation strength,
+while for correlated amplitude damping and correlated squeezed generalized
+amplitude damping channels quantum speed limit time is decreased by increasing
+correlation strength.",1901.08917v4
+2019-02-17,Finite-size effects on sound damping in stable computer glasses,"In this brief note we comment on the recent results presented in
+arXiv:1812.08736v1",1902.06225v1
+2019-05-04,A class of second-order geometric quasilinear hyperbolic PDEs and their application in imaging science,"In this paper, we study damped second-order dynamics, which are quasilinear
+hyperbolic partial differential equations (PDEs). This is inspired by the
+recent development of second-order damping systems for accelerating energy
+decay of gradient flows. We concentrate on two equations: one is a damped
+second-order total variation flow, which is primarily motivated by the
+application of image denoising; the other is a damped second-order mean
+curvature flow for level sets of scalar functions, which is related to a
+non-convex variational model capable of correcting displacement errors in image
+data (e.g. dejittering). For the former equation, we prove the existence and
+uniqueness of the solution. For the latter, we draw a connection between the
+equation and some second-order geometric PDEs evolving the hypersurfaces which
+are described by level sets of scalar functions, and show the existence and
+uniqueness of the solution for a regularized version of the equation. The
+latter is used in our algorithmic development. A general algorithm for
+numerical discretization of the two nonlinear PDEs is proposed and analyzed.
+Its efficiency is demonstrated by various numerical examples, where simulations
+on the behavior of solutions of the new equations and comparisons with
+first-order flows are also documented.",1905.01457v2
+2019-08-20,Synthetic Extreme-ultraviolet Emissions Modulated by Leaky Fast Sausage Modes in Solar Active Region Loops,"We study the extreme-ultraviolet (EUV) emissions modulated by leaky fast
+sausage modes (FSMs) in solar active region loops and examine their
+observational signatures via spectrometers like EIS. After computing fluid
+variables of leaky FSMs with MHD simulations, we forward-model the intensity
+and spectral properties of the Fe X 185~\AA~and Fe XII 195~\AA~lines by
+incorporating non-equilibrium ionization (NEI) in the computations of the
+relevant ionic fractions. The damping times derived from the intensity
+variations are then compared with the wave values, namely the damping times
+directly found from our MHD simulations. Our results show that in the
+equilibrium ionization cases, the density variations and the intensity
+variations can be either in phase or in anti-phase, depending on the loop
+temperature. NEI considerably impacts the intensity variations but has only
+marginal effects on the derived Doppler velocity or Doppler width. We find that
+the damping time derived from the intensity can largely reflect the wave
+damping time if the loop temperature is not drastically different from the
+nominal formation temperature of the corresponding emission line. These results
+are helpful for understanding the modulations to the EUV emissions by leaky
+FSMs and hence helpful for identifying FSMs in solar active region loops.",1908.07131v1
+2019-10-24,Frequency criteria for exponential stability,"We discuss some frequency-domain criteria for the exponential stability of
+nonlinear feedback systems based on dissipativity theory. Applications are
+given to convergence rates for certain perturbations of the damped harmonic
+oscillator.",1910.10855v2
+2019-11-05,IW And-Type State in IM Eridani,"IW And stars are a recently recognized group of dwarf novae which are
+characterized by a repeated sequence of brightening from a standstill-like
+phase with damping oscillations followed by a deep dip. Kimura et al. (2019)
+recently proposed a model based on thermal-viscous disk instability in a tilted
+disk to reproduce the IW And-type characteristics. IM Eri experienced the IW
+And-type phase in 2018 and we recorded three cycles of the (damping)
+oscillation phase terminated by brightening. We identified two periods during
+the IW And-type state: 4-5 d small-amplitude (often damping) oscillations and a
+34-43 d long cycle. This behavior is typical for an IW And-type star. The
+object gradually brightened within the long cycle before the next brightening
+which terminated the (damping) oscillation phase. This observation agrees with
+the increasing disk mass during the long cycle predicted by a model of
+thermal-viscous disk instability in a tilted disk (Kimura et al. 2019). We,
+however, did not succeed in detecting negative superhumps, which are considered
+to be the signature of a tilted disk.",1911.01587v1
+2019-11-28,Magnon damping in the zigzag phase of the Kitaev-Heisenberg-$Γ$ model on a honeycomb lattice,"We calculate magnon dispersions and damping in the Kitaev-Heisenberg model
+with an off-diagonal exchange $\Gamma$ and isotropic third-nearest-neighbor
+interaction $J_3$ on a honeycomb lattice. This model is relevant to a
+description of the magnetic properties of iridium oxides $\alpha$-Li$_2$IrO$_3$
+and Na$_2$IrO$_3$, and Ru-based materials such as $\alpha$-RuCl$_3$. We use an
+unconventional parametrization of the spin-wave expansion, in which each
+Holstein-Primakoff boson is represented by two conjugate hermitian operators.
+This approach gives us an advantage over the conventional one in identifying
+parameter regimes where calculations can be performed analytically. Focusing on
+the parameter regime with the zigzag spin pattern in the ground state that is
+consistent with experiments, we demonstrate that one such region is $\Gamma =
+K>0$, where $K$ is the Kitaev coupling. Within our approach we are able to
+obtain explicit analytical expressions for magnon energies and eigenstates and
+go beyond the standard linear spin-wave theory approximation by calculating
+magnon damping and demonstrating its role in the dynamical structure factor. We
+show that the magnon damping effects in both Born and self-consistent
+approximations are very significant, underscoring the importance of non-linear
+magnon coupling in interpreting broad features in the neutron-scattering
+spectra.",1911.12829v2
+2019-12-10,A Stochastic Quasi-Newton Method for Large-Scale Nonconvex Optimization with Applications,"This paper proposes a novel stochastic version of damped and regularized BFGS
+method for addressing the above problems.",1912.04456v1
+2019-12-27,Ultralow mechanical damping with Meissner-levitated ferromagnetic microparticles,"Levitated nanoparticles and microparticles are excellent candidates for the
+realization of extremely isolated mechanical systems, with a huge potential
+impact in sensing applications and in quantum physics. Magnetic levitation
+based on static fields is a particularly interesting approach, due to the
+unique property of being completely passive and compatible with low
+temperatures. Here, we show experimentally that micromagnets levitated above
+type-I superconductors feature very low damping at low frequency and low
+temperature. In our experiment, we detect 5 out of 6 rigid-body mechanical
+modes of a levitated ferromagnetic microsphere, using a dc SQUID
+(Superconducting Quantum Interference Device) with a single pick-up coil. The
+measured frequencies are in agreement with a finite element simulation based on
+ideal Meissner effect. For two specific modes we find further substantial
+agreement with analytical predictions based on the image method. We measure
+damping times $\tau$ exceeding $10^4$ s and quality factors $Q$ beyond $10^7$,
+improving by $2-3$ orders of magnitude over previous experiments based on the
+same principle. We investigate the possible residual loss mechanisms besides
+gas collisions, and argue that much longer damping time can be achieved with
+further effort and optimization. Our results open the way towards the
+development of ultrasensitive magnetomechanical sensors with potential
+applications to magnetometry and gravimetry, as well as to fundamental and
+quantum physics.",1912.12252v3
+2020-01-22,Wide Area Measurement System-based Low Frequency Oscillation Damping Control through Reinforcement Learning,"Ensuring the stability of power systems is gaining more attraction today than
+ever before, due to the rapid growth of uncertainties in load and renewable
+energy penetration. Lately, wide area measurement system-based centralized
+controlling techniques started providing a more flexible and robust control to
+keep the system stable. But, such a modernization of control philosophy faces
+pressing challenges due to the irregularities in delays of long-distance
+communication channels and response of equipment to control actions. Therefore,
+we propose an innovative approach that can revolutionize the control strategy
+for damping down low frequency oscillations in transmission systems. Proposed
+method is enriched with a potential of overcoming the challenges of
+communication delays and other non-linearities in wide area damping control by
+leveraging the capability of the reinforcement learning technique. Such a
+technique has a unique characteristic to learn on diverse scenarios and
+operating conditions by exploring the environment and devising an optimal
+control action policy by implementing policy gradient method. Our detailed
+analysis and systematically designed numerical validation prove the
+feasibility, scalability and interpretability of the carefully modelled
+low-frequency oscillation damping controller so that stability is ensured even
+with the uncertainties of load and generation are on the rise.",2001.07829v1
+2020-02-13,Semi-realistic tight-binding model for spin-orbit torques,"We compute the spin-orbit torque in a transition metal heterostructure using
+Slater-Koster parameterization in the two-center tight-binding approximation
+and accounting for d-orbitals only. In this method, the spin-orbit coupling is
+modeled within Russel-Saunders scheme, which enables us to treat interfacial
+and bulk spin-orbit transport on equal footing. The two components of the
+spin-orbit torque, dissipative (damping-like) and reactive (field-like), are
+computed within Kubo linear response theory. By systematically studying their
+thickness and angular dependence, we were able to accurately characterize these
+components beyond the traditional ""inverse spin galvanic"" and ""spin Hall""
+effects. Whereas the conventional field-like torque is purely interfacial, we
+unambiguously demonstrate that the conventional the damping-like torque
+possesses both an interfacial and a bulk contribution. In addition, both
+field-like and damping-like torques display substantial angular dependence with
+strikingly different thickness behavior. While the planar contribution of the
+field-like torque decreases smoothly with the nonmagnetic metal thickness, the
+planar contribution of the damping-like torque increases dramatically with the
+nonmagnetic metal thickness. Finally, we investigate the self-torque exerted on
+the ferromagnet when the spin-orbit coupling of the nonmagnetic metal is turned
+off. Our results suggest that the spin accumulation that builds up inside the
+ferromagnet can be large enough to induce magnetic excitations.",2002.05533v1
+2020-02-14,"One-dimensional wave equation with set-valued boundary damping: well-posedness, asymptotic stability, and decay rates","This paper is concerned with the analysis of a one dimensional wave equation
+$z_{tt}-z_{xx}=0$ on $[0,1]$ with a Dirichlet condition at $x=0$ and a damping
+acting at $x=1$ which takes the form $(z_t(t,1),-z_x(t,1))\in\Sigma$ for every
+$t\geq 0$, where $\Sigma$ is a given subset of $\mathbb R^2$. The study is
+performed within an $L^p$ functional framework, $p\in [1, +\infty]$. We aim at
+determining conditions on $\Sigma$ ensuring existence and uniqueness of
+solutions of that wave equation as well as strong stability and uniform global
+asymptotic stability of its solutions. In the latter case, we also study the
+decay rates of the solutions and their optimality. We first establish a
+one-to-one correspondence between the solutions of that wave equation and the
+iterated sequences of a discrete-time dynamical system in terms of which we
+investigate the above mentioned issues. This enables us to provide a simple
+necessary and sufficient condition on $\Sigma$ ensuring existence and
+uniqueness of solutions of the wave equation as well as an efficient strategy
+for determining optimal decay rates when $\Sigma$ verifies a generalized sector
+condition. As an application, we solve two conjectures stated in the
+literature, the first one seeking a specific optimal decay rate and the second
+one associated with a saturation type of damping. In case the boundary damping
+is subject to perturbations, we derive sharp results regarding asymptotic
+perturbation rejection and input-to-state issues.",2002.06186v3
+2020-03-30,Optimal absorption of acoustical waves by a boundary,"In the aim to find the simplest and most efficient shape of a noise absorbing
+wall to dissipate the acoustical energy of a sound wave, we consider a
+frequency model described by the Helmholtz equation with a damping on the
+boundary. The well-posedness of the model is shown in a class of domains with
+d-set boundaries (N -- 1 $\le$ d < N). We introduce a class of admissible
+Lipschitz boundaries, in which an optimal shape of the wall exists in the
+following sense: We prove the existence of a Radon measure on this shape,
+greater than or equal to the usual Lebesgue measure, for which the
+corresponding solution of the Helmholtz problem realizes the infimum of the
+acoustic energy defined with the Lebesgue measure on the boundary. If this
+Radon measure coincides with the Lebesgue measure, the corresponding solution
+realizes the minimum of the energy. For a fixed porous material, considered as
+an acoustic absorbent, we derive the damping parameters of its boundary from
+the corresponding time-dependent problem described by the damped wave equation
+(damping in volume).",2003.13250v2
+2020-04-24,Suppression of the longitudinal coupled bunch instability in DA$Φ$NE in collisions with a crossing angle,"In DAFNE, the Frascati $e^+e^-$ collider operating since 1998, an innovative
+collision scheme, the crab waist, has been successfully implemented during the
+years 2008-09. During operations for the Siddharta experiment an unusual
+synchrotron oscillation damping effect induced by beam-beam collisions has been
+observed. Indeed, when the longitudinal feedback is off, the positron beam
+becomes unstable with currents above 200-300 mA due to coupled bunch
+instability. The longitudinal instability is damped by colliding the positron
+beam with a high current electron beam (of the order of 2 A). A shift of about
+-600 Hz in the residual synchrotron sidebands is observed. Precise measurements
+have been performed by using both a commercial spectrum analyzer and the
+diagnostic capabilities of the longitudinal bunch-by-bunch feedback. The
+damping effect has been observed in DAFNE for the first time during collisions
+with the crab waist scheme. Our explanation, based both on theoretical
+consideration and modeling simulation, is that beam collisions with a large
+crossing angle produce longitudinal tune shift and spread, providing Landau
+damping of synchrotron oscillations.",2004.11902v1
+2020-05-08,Separatrix crossing and symmetry breaking in NLSE-like systems due to forcing and damping,"We theoretically and experimentally examine the effect of forcing and damping
+on systems that can be described by the nonlinear Schr\""odinger equation
+(NLSE), by making use of the phase-space predictions of the three-wave
+truncation of the spectrum. In the latter, only the fundamental frequency and
+the upper and lower sidebands are retained. Plane wave solutions to the NLSE
+exhibit modulation instability (MI) within a frequency band determined by a
+linear stability analysis. For modulation frequencies inside the MI-band, we
+experimentally demonstrate that forcing and damping cause a separatrix crossing
+during the evolution. Our experiments are performed on deep water waves, which
+are better described by the higher-order NLSE, the Dysthe equation. We
+therefore extend our analysis to this system. However, our conclusions are
+general. When the system is damped by the viscosity of the water, it is pulled
+outside the separatrix, which in the real space corresponds to a phase-shift of
+the envelope and therefore doubles the period of the Fermi-Pasta-Ulam-Tsingou
+recurrence cycle. When the system is forced by the wind, it is pulled inside
+the separatrix. Furthermore, for modulation frequencies outside the
+conventional MI-band, we experimentally demonstrate that contrary to the linear
+prediction, we do observe a growth and decay cycle of the plane-wave
+modulation. Finally, we give a theoretical demonstration that forcing the NLSE
+system can induce symmetry breaking during the evolution.",2005.03931v1
+2020-05-13,Damping of a micro-electromechanical oscillator in turbulent superfluid $^4$He: A novel probe of quantized vorticity in the ultra-low temperature regime,"We report a comprehensive investigation of the effects of quantum turbulence
+and quantized vorticity in superfluid $^4$He on the motion of a
+micro-electromechanical systems (MEMS) resonator. We find that the MEMS is
+uniquely sensitive to quantum turbulence present in the fluid. To generate
+turbulence in the fluid, a quartz tuning fork (TF) is placed in proximity to
+the MEMS and driven at large amplitude. We observe that at low velocity, the
+MEMS is damped by the turbulence, and that above a critical velocity, $v_c
+\simeq 5\,$mm\,s$^{-1}$, the turbulent damping is greatly reduced. We find that
+above $v_c$, the damping of the MEMS is reduced further for increasing
+velocity, indicating a velocity dependent coupling between the surface of the
+MEMS and the quantized vortices constituting the turbulence. We propose a model
+of the interaction between vortices in the fluid and the surface of the MEMS.
+The sensitivity of these devices to a small number of vortices and the almost
+unlimited customization of MEMS open the door to a more complete understanding
+of the interaction between quantized vortices and oscillating structures, which
+in turn provides a new route for the investigation of the dynamics of single
+vortices.",2005.06570v1
+2020-06-10,Online PMU-Based Wide-Area Damping Control for Multiple Inter-Area Modes,"This paper presents a new phasor measurement unit (PMU)-based wide-area
+damping control (WADC) method to suppress the critical inter-area modes of
+large-scale power systems. Modal participation factors, estimated by a
+practically model-free system identification approach, are used to select the
+most suitable synchronous generators for control through the proposed WADC
+algorithm. It is shown that multiple inter-area modes can be sufficiently
+damped by the proposed approach without affecting the rest of the modes, while
+only a few machines are needed to perform the control. The proposed technique
+is applied to the IEEE 68-bus and the IEEE 145-bus systems, including the test
+cases with PMU measurement noise and with missing PMUs. The simulation results
+clearly demonstrate the good adaptivity of the control strategy subjected to
+network model changes, its effective damping performance comparing to power
+system stabilizers (PSSs), and its great potential for near real-time
+implementation.",2006.05651v1
+2020-06-14,A general formulation for the magnetic oscillations in two dimensional systems,"We develop a general formalism for the magnetic oscillations (MO) in two
+dimensional (2D) systems. We consider general 2D Landau levels, which may
+depend on other variable or indices, besides the perpendicular magnetic field.
+In the ground state, we obtain expressions for the MO phase and amplitude. From
+this we use a Fourier expansion to write the MO, with the first term being a
+sawtooth oscillation. We also consider the effects of finite temperature,
+impurities or lattice imperfections, assuming a general broadening of the
+Landau levels. We develop two methods for describing these damping effects in
+the MO. One in terms of the occupancy of the Landau levels, the other in terms
+of reduction factors, which results in a generalization of the
+Lifshits-Kosevich (LK) formula. We show that the first approach is particularly
+useful at very low damping, when only the states close to the Fermi energy are
+excited. In contrast, the LK formula may be more convenient at higher damping,
+when only few terms are needed in its harmonic expansion. We compare different
+damping situations, showing how the MO are broadened in each case. The general
+formulation presented allows to relate the properties of the MO with those of
+the 2D systems.",2006.07944v2
+2020-08-26,Quantum Lifshitz points and fluctuation-induced first-order phase transitions in imbalanced Fermi mixtures,"We perform a detailed analysis of the phase transition between the uniform
+superfluid and normal phases in spin- and mass-imbalanced Fermi mixtures. At
+mean-field level we demonstrate that at temperature $T\to 0$ the gradient term
+in the effective action can be tuned to zero for experimentally relevant sets
+of parameters, thus providing an avenue to realize a quantum Lifshitz point. We
+subsequently analyze damping processes affecting the order-parameter field
+across the phase transition. We show that, in the low energy limit, Landau
+damping occurs only in the symmetry-broken phase and affects exclusively the
+longitudinal component of the order-parameter field. It is however unavoidably
+present in the immediate vicinity of the phase transition at temperature $T=0$.
+We subsequently perform a renormalization-group analysis of the system in a
+situation, where, at mean-field level, the quantum phase transition is second
+order (and not multicritical). We find that, at $T$ sufficiently low, including
+the Landau damping term in a form derived from the microscopic action
+destabilizes the renormalization group flow towards the Wilson-Fisher fixed
+point. This signals a possible tendency to drive the transition weakly
+first-order by the coupling between the order-parameter fluctuations and
+fermionic excitations effectively captured by the Landau damping contribution
+to the order-parameter action.",2008.11782v1
+2020-09-10,Electron Landau Damping of Kinetic Alfvén Waves in Simulated Magnetosheath Turbulence,"Turbulence is thought to play a role in the heating of the solar wind plasma,
+though many questions remain to be solved regarding the exact nature of the
+mechanisms driving this process in the heliosphere. In particular, the physics
+of the collisionless interactions between particles and turbulent
+electromagnetic fields in the kinetic dissipation range of the turbulent
+cascade remains incompletely understood. A recent analysis of an interval of
+Magnetosphere Multiscale (MMS) observations has used the field-particle
+correlation technique to demonstrate that electron Landau damping is involved
+in the dissipation of turbulence in the Earth's magnetosheath. Motivated by
+this discovery, we perform a high-resolution gyrokinetic numerical simulation
+of the turbulence in the MMS interval to investigate the role of electron
+Landau damping in the dissipation of turbulent energy. We employ the
+field-particle correlation technique on our simulation data, compare our
+results to the known velocity-space signatures of Landau damping outside the
+dissipation range, and evaluate the net electron energization. We find
+qualitative agreement between the numerical and observational results for some
+key aspects of the energization and speculate on the nature of disagreements in
+light of experimental factors, such as differences in resolution, and of
+developing insights into the nature of field-particle interactions in the
+presence of dispersive kinetic Alfv\'en waves.",2009.05010v1
+2020-11-09,Plasmon energy losses in shear bands of metallic glass,"Shear bands resulting from plastic deformation in cold-rolled
+Al$_{88}$Y$_{7}$Fe$_{5}$ metallic glass were observed to display alternating
+density changes along their propagation direction. Electron-energy loss
+spectroscopy (EELS) was used to investigate the volume plasmon energy losses in
+and around shear bands. Energy shifts of the peak centre and changes in the
+peak width (FWHM) reflecting the damping were precisely determined within an
+accuracy of a few meV using an open source python module (Hyperspy) to fit the
+shapes of the plasmon and zero-loss peaks with Lorentzian functions. The
+maximum bulk plasmon energy shifts were calculated for the bright and dark
+shear band segments relative to the matrix to be about 38 and 14 meV,
+respectively. The damping was observed to be larger for the denser regions. The
+analysis presented here suggests that the changes in the plasmons are caused by
+two contributions: (i) Variable damping in the shear band segments due to
+changes in the medium-range order (MRO). This affects the static structure
+factor S(k), which, in turn, leads to either reduced or increased damping
+according to the Ziman-Baym formula. (ii) The ionic density and the effective
+electron mass appearing in the zero-momentum plasmon frequency formula
+$E_p(q=0)$ are coupled and give rise to small variations in the plasmon energy.
+The model predicts plasmon energy shifts in the order of meV.",2011.04396v3
+2020-11-16,Thresholds for loss of Landau damping in longitudinal plane,"Landau damping mechanism plays a crucial role in providing single-bunch
+stability in LHC, High-Luminosity LHC, other existing as well as previous and
+future (like FCC) circular hadron accelerators. In this paper, the thresholds
+for the loss of Landau damping (LLD) in the longitudinal plane are derived
+analytically using the Lebedev matrix equation (1968) and the concept of the
+emerged van Kampen modes (1983). We have found that for the commonly-used
+particle distribution functions from a binomial family, the LLD threshold
+vanishes in the presence of the constant inductive impedance Im$Z/k$ above
+transition energy. Thus, the effect of the cutoff frequency or the resonant
+frequency of a broad-band impedance on beam dynamics is studied in detail. The
+findings are confirmed by direct numerical solutions of the Lebedev equation as
+well as using the Oide-Yokoya method (1990). Moreover, the characteristics,
+which are important for beam operation, as the amplitude of residual
+oscillations and the damping time after a kick (or injection errors) are
+considered both above and below the threshold. Dependence of the threshold on
+particle distribution in the longitudinal phase space is also analyzed,
+including some special cases with a non-zero threshold for Im$Z/k = const$. All
+main results are confirmed by macro-particle simulations and consistent with
+available beam measurements in the LHC.",2011.07985v1
+2020-12-04,Quantum Circuits for Collective Amplitude Damping in Two-Qubit Systems,"Quantum computers have now appeared in our society and are utilized for the
+investigation of science and engineering. At present, they have been built as
+intermediate-size computers containing about fifty qubits and are weak against
+noise effects. Hence, they are called noisy-intermediate scale quantum devices.
+In order to accomplish efficient quantum computation with using these machines,
+a key issue is going to be the coherent control of individual and collective
+quantum noises. In this work, we focus on a latter type and investigate
+formulations of the collective quantum noises represented as quantum circuits.
+To simplify our discussions and make them concrete, we analyze collective
+amplitude damping processes in two-qubit systems. As verifications of our
+formalisms and the quantum circuits, we demonstrate digital quantum simulations
+of the collective amplitude damping by examining six different initial
+conditions with varying the number of execution of an overall operation for our
+quantum simulations. We observe that our results show good numerical matching
+with the solution of quantum master equation for the two-qubit systems as we
+increase such a number. In addition, we explain the essence of the way to
+extend our formalisms to analyze the collective amplitude damping in larger
+qubit systems. These results pave the way for establishing systematic
+approaches to control the quantum noises and designing large-scale quantum
+computers.",2012.02410v1
+2020-12-10,Dimensional analysis of spring-wing systems reveals performance metrics for resonant flapping-wing flight,"Flapping-wing insects, birds, and robots are thought to offset the high power
+cost of oscillatory wing motion by using elastic elements for energy storage
+and return. Insects possess highly resilient elastic regions in their flight
+anatomy that may enable high dynamic efficiency. However, recent experiments
+highlight losses due to damping in the insect thorax that could reduce the
+benefit of those elastic elements. We performed experiments on, and simulations
+of a dynamically-scaled robophysical flapping model with an elastic element and
+biologically-relevant structural damping to elucidate the roles of body
+mechanics, aerodynamics, and actuation in spring-wing energetics. We measured
+oscillatory flapping wing dynamics and energetics subject to a range of
+actuation parameters, system inertia, and spring elasticity. To generalize
+these results, we derive the non-dimensional spring-wing equation of motion and
+present variables that describe the resonance properties of flapping systems:
+$N$, a measure of the relative influence of inertia and aerodynamics, and
+$\hat{K}$, the reduced stiffness. We show that internal damping scales with
+$N$, revealing that dynamic efficiency monotonically decreases with increasing
+$N$. Based on these results, we introduce a general framework for understanding
+the roles of internal damping, aerodynamic and inertial forces, and elastic
+structures within all spring-wing systems.",2012.05428v1
+2021-03-11,Nontrivial damping of quantum many-body dynamics,"Understanding how the dynamics of a given quantum system with many degrees of
+freedom is altered by the presence of a generic perturbation is a notoriously
+difficult question. Recent works predict that, in the overwhelming majority of
+cases, the unperturbed dynamics is just damped by a simple function, e.g.,
+exponentially as expected from Fermi's golden rule. While these predictions
+rely on random-matrix arguments and typicality, they can only be verified for a
+specific physical situation by comparing to the actual solution or measurement.
+Crucially, it also remains unclear how frequent and under which conditions
+counterexamples to the typical behavior occur. In this work, we discuss this
+question from the perspective of projection-operator techniques, where
+exponential damping of a density matrix occurs in the interaction picture but
+not necessarily in the Schr\""odinger picture. We show that a nontrivial damping
+in the Schr\""odinger picture can emerge if the dynamics in the unperturbed
+system possesses rich features, for instance due to the presence of strong
+interactions. This suggestion has consequences for the time dependence of
+correlation functions. We substantiate our theoretical arguments by large-scale
+numerical simulations of charge transport in the extended Fermi-Hubbard chain,
+where the nearest-neighbor interactions are treated as a perturbation to the
+integrable reference system.",2103.06646v2
+2021-03-24,"Multimode piezoelectric shunt damping of thin plates with arrays of separately shunted patches, method, and experimental validation","Two-dimensional thin plates are widely used in many applications. Shunt
+damping is a promising way for the attenuation of vibration of these
+electromechanical systems. It enables a compact vibration damping method
+without adding significant mass and volumetric occupancy. Analyzing the
+dynamics of such electromechanical systems requires precise modeling tools that
+properly consider the coupling between the piezoelectric elements and the host
+structure. Although the concept of shunt damping has been studied extensively
+in the literature, most of the studies do not provide a formulation for
+modeling the multiple piezoelectric patches that are scattered on the host
+structure and shunted separately. This paper presents a methodology and a
+formulation for separately shunted piezoelectric patches for achieving higher
+performance on vibration attenuation. The Rayleigh-Ritz method is used for
+performing modal analysis and obtaining the frequency response functions of the
+electro-mechanical system. The developed model includes mass and stiffness
+contribution of the piezoelectric patches as well as the electromechanical
+coupling effect. In this study, the piezoelectric patches are shunted via
+separate electrical circuits and compared with the ones those are shunted via
+interconnected electrical circuits. For verification, system-level finite
+element simulations are performed in ANSYS software and compared with the
+analytical model results. An experimental setup is also built to validate the
+performance of the separately shunted piezoelectric patches. The effectiveness
+of the method is investigated for a broader range of frequencies and it was
+shown that separately shunted piezoelectric patches are more effective compared
+to connected for a wide range of frequencies.",2103.13179v1
+2021-04-09,Taming the pinch singularities in the two-loop neutrino self-energy in a medium,"We consider the calculation of the thermal self-energy of a neutrino that
+propagates in a medium composed of fermions and scalars interacting via a
+Yukawa-type coupling, in the case that the neutri no energy is much larger than
+the fermion and scalar masses, as well as the temperature and chemical
+potentials of the background. In this kinematic regime the one-loop
+contribution to the imaginary part of the self-energy is negligible. We
+consider the two-loop contribution and we encounter the so-called pinch
+singularities which are known to arise in higher loop self-energy calculations
+in Thermal Field Theory. With a judicious use of the properties and
+parametrizations of the thermal propagators the singularities are treated
+effectively and actually disappear. From the imaginary part of the self-energy,
+we obtain a precise formula for the damping matrix expressed in terms of
+integrals over the background particle distributions. The formulas predict a
+specific dependence of the damping terms on the neutrino energy, depending on
+the background conditions. For guidance to estimating the effects in specific
+contexts, we compute the damping terms for several limiting cases of the
+momentum distribution functions of the background particles. We discuss briefly
+the connection between the results of our calculations for the damping matrix
+and the decoherence effects described in terms of the Lindblad equation.",2104.04459v2
+2021-06-20,Life-cycle assessment for flutter probability of a long-span suspension bridge based on field monitoring data,"Assessment of structural safety status is of paramount importance for
+existing bridges, where accurate evaluation of flutter probability is essential
+for long-span bridges. In current engineering practice, at the design stage,
+flutter critical wind speed is usually estimated by the wind tunnel test, which
+is sensitive to modal frequencies and damping ratios. After construction,
+structural properties of existing structures will change with time due to
+various factors, such as structural deteriorations and periodic environments.
+The structural dynamic properties, such as modal frequencies and damping
+ratios, cannot be considered as the same values as the initial ones, and the
+deteriorations should be included when estimating the life-cycle flutter
+probability. This paper proposes an evaluation framework to assess the
+life-cycle flutter probability of long-span bridges considering the
+deteriorations of structural properties, based on field monitoring data. The
+Bayesian approach is employed for modal identification of a suspension bridge
+with the main span of 1650 m, and the field monitoring data during 2010-2015 is
+analyzed to determine the deterioration functions of modal frequencies and
+damping ratios, as well as their inter-seasonal fluctuations. According to the
+historical trend, the long-term structural properties can be predicted, and the
+probability distributions of flutter critical wind speed for each year in the
+long term are calculated. Consequently, the life-cycle flutter probability is
+estimated, based on the predicted modal frequencies and damping ratios.",2106.10694v1
+2021-07-28,Optimal gamma-ray selections for monochromatic line searches with DAMPE,"The DArk Matter Particle Explorer (DAMPE) is a space high-energy cosmic-ray
+detector covering a wide energy band with a high energy resolution. One of the
+key scientific goals of DAMPE is to carry out indirect detection of dark matter
+by searching for high-energy gamma-ray line structure. To promote the
+sensitivity of gamma-ray line search with DAMPE, it is crucial to improve the
+acceptance and energy resolution of gamma-ray photons. In this paper, we
+quantitatively prove that the photon sample with the largest ratio of
+acceptance to energy resolution is optimal for line search. We therefore
+develop a line-search sample specifically optimized for the line search.
+Meanwhile, in order to increase the statistics, we also selected the so called
+BGO-only photons that convert into $e^+e^-$ pairs only in the BGO calorimeter.
+The standard, the line-search, and the BGO-only photon samples are then tested
+for line search individually and collectively. The results show that a
+significantly improved limit could be obtained from an appropriate combination
+of the date sets, and the increase is about 20\% for the highest case compared
+with using the standard sample only.",2107.13208v2
+2021-07-28,Magnetic field induced asymmetric splitting of the output signal,"In this paper we have investigated the dynamics of a damped harmonic
+oscillator in the presence of an electromagnetic field. The transients for the
+two dimensional harmonic oscillator imply about the modulation of the frequency
+of the oscillator by the velocity dependent non conservative force from an
+applied magnetic field. Except a special condition, the motion is in general
+quasi periodic nature even in the absence of damping. Another interesting
+finding is that the magnetic field may induce an asymmetric splitting of the
+spectrum of the output signal with two peaks in the case of a driven damped two
+dimensional harmonic oscillator. One more additional peak may appear for the
+three dimensional case. In some cases the spectrum may have similarity with the
+Normal Zeeman Effect. At the same time one may observe to appear the anti
+resonance phenomenon even for the driven damped cyclotron motion where the
+system with the purely non conservative force fields is driven by an electric
+field. Finally, our calculation exhibits how the magnetic field can modulate
+the phase difference (between input and output signals) and the efficiency like
+quantity of the energy storing process. Thus the present study might be
+applicable in the areas related to the refractive index, the barrier crossing
+dynamics and autonomous stochastic resonance, respectively.",2107.13305v1
+2021-07-28,Evolution of a Mode of Oscillation Within Turbulent Accretion Disks,"We investigate the effects of subsonic turbulence on a normal mode of
+oscillation [a possible origin of the high-frequency quasi-periodic
+oscillations (HFQPOs) within some black hole accretion disks]. We consider
+perturbations of a time-dependent background (steady state disk plus
+turbulence), obtaining an oscillator equation with stochastic damping, (mildly)
+nonlinear restoring, and stochastic driving forces. The (long-term) mean values
+of our turbulent functions vanish. In particular, turbulence does not damp the
+oscillation modes, so `turbulent viscosity' is not operative. However, the
+frequency components of the turbulent driving force near that of the mode can
+produce significant changes in the amplitude of the mode. Even with an
+additional (phenomenological constant) source of damping, this leads to an
+eventual `blowout' (onset of effects of nonlinearity) if the turbulence is
+sufficiently strong or the damping constant is sufficiently small. The
+infrequent large increases in the energy of the mode could be related to the
+observed low duty cycles of the HFQPOs. The width of the peak in the power
+spectral density (PSD) is proportional to the amount of nonlinearity. A
+comparison with observed continuum PSDs indicates the conditions required for
+visibility of the mode.",2107.13546v1
+2021-07-31,Oscillating scalar dissipating in a medium,"We study how oscillations of a scalar field condensate are damped due to
+dissipative effects in a thermal medium. Our starting point is a non-linear and
+non-local condensate equation of motion descending from a 2PI-resummed
+effective action derived in the Schwinger-Keldysh formalism appropriate for
+non-equilibrium quantum field theory. We solve this non-local equation by means
+of multiple-scale perturbation theory appropriate for time-dependent systems,
+obtaining approximate analytic solutions valid for very long times. The
+non-linear effects lead to power-law damping of oscillations, that at late
+times transition to exponentially damped ones characteristic for linear
+systems. These solutions describe the evolution very well, as we demonstrate
+numerically in a number of examples. We then approximate the non-local equation
+of motion by a Markovianised one, resolving the ambiguities appearing in the
+process, and solve it utilizing the same methods to find the very same leading
+approximate solution. This comparison justifies the use of Markovian equations
+at leading order. The standard time-dependent perturbation theory in comparison
+is not capable of describing the non-linear condensate evolution beyond the
+early time regime of negligible damping. The macroscopic evolution of the
+condensate is interpreted in terms of microphysical particle processes. Our
+results have implications for the quantitative description of the decay of
+cosmological scalar fields in the early Universe, and may also be applied to
+other physical systems.",2108.00254v1
+2021-08-02,Large-amplitude longitudinal oscillations in solar prominences simulated with different resolutions,"Large-amplitude longitudinal oscillations (LALOs) in solar prominences have
+been widely studied in the last decades. However, their damping and
+amplification mechanisms are not well understood. In this study, we investigate
+the attenuation and amplification of LALOs using high-resolution numerical
+simulations with progressively increasing spatial resolutions. We performed
+time-dependent numerical simulations of LALOs using the 2D magnetic
+configuration that contains a dipped region. After the prominence mass loading
+in the magnetic dips, we triggered LALOs by perturbing the prominence mass
+along the magnetic field. We performed the experiments with four values of
+spatial resolution. In the simulations with the highest resolution, the period
+shows a good agreement with the pendulum model. The convergence experiment
+revealed that the damping time saturates at the bottom prominence region with
+improving the resolution, indicating the existence of a physical reason for the
+damping of oscillations. At the prominence top, the oscillations are amplified
+during the first minutes and then are slowly attenuated. The characteristic
+time suggests more significant amplification in the experiments with the
+highest spatial resolution. The analysis revealed that the energy exchange
+between the bottom and top prominence regions is responsible for the
+attenuation and amplification of LALOs. The high-resolution experiments are
+crucial for the study of the periods and the damping mechanism of LALOs. The
+period agrees with the pendulum model only when using high enough spatial
+resolution. The results suggest that numerical diffusion in simulations with
+insufficient spatial resolution can hide important physical mechanisms, such as
+amplification of oscillations.",2108.01143v1
+2021-08-05,Complexity analysis of quantum teleportation via different entangled channels in the presence of noise,"Quantum communication is one of the hot topics in quantum computing, where
+teleportation of a quantum state has a slight edge and gained significant
+attention from researchers. A large number of teleportation schemes have
+already been introduced so far. Here, we compare the teleportation of a single
+qubit message among different entangled channels such as the two-qubit Bell
+channel, three-qubit GHZ channel, two- and three-qubit cluster states, the
+highly entangled five-qubit Brown \emph{et al.} state and the six-qubit Borras
+\emph{et al.} state. We calculate and compare the quantum costs in each of the
+cases. Furthermore, we study the effects of six noise models, namely bit-flip
+noise, phase-flip noise, bit-phase flip noise, amplitude damping, phase damping
+and the depolarizing error that may affect the communication channel used for
+the teleportation. An investigation on the variation of the initial state's
+fidelity with respect to the teleported state in the presence of the noise
+model is performed. A visual representation of the variation of fidelity for
+various values of the noise parameter $\eta$ is done through a graph plot. It
+is observed that as the value of noise parameter in the range $\eta \in
+[0,0.5]$, the fidelity decreases in all the entangled channels under all the
+noise models. After that, in the Bell channel, GHZ channel and three-qubit
+cluster state channel, the fidelity shows an upward trend under all the noise
+models. However, in the other three channels, the fidelity substantially
+decreases in the case of amplitude damping, phase damping and depolarizing
+noise, and even it reaches zero for $\eta = 1$ in Brown \emph{et al.} and
+Borras \emph{et al.} channels.",2108.02641v1
+2021-08-06,Noncontact friction: Role of phonon damping and its nonuniversality,"While obtaining theoretical predictions for dissipation during sliding motion
+is a difficult task, one regime that allows for analytical results is the
+so-called noncontact regime, where a probe is weakly interacting with the
+surface over which it moves. Studying this regime for a model crystal, we
+extend previously obtained analytical results and confirm them quantitatively
+via particle based computer simulations. Accessing the subtle regime of weak
+coupling in simulations is possible via use of Green-Kubo relations. The
+analysis allows to extract and compare the two paradigmatic mechanisms that
+have been found to lead to dissipation: phonon radiation, prevailing even in a
+purely elastic solid, and phonon damping, e.g., caused by viscous motion of
+crystal atoms. While phonon radiation is dominant at large probe-surface
+distances, phonon damping dominates at small distances. Phonon radiation is
+furthermore a pairwise additive phenomenon so that the dissipation due to
+interaction with different parts (areas) of the surface adds up. This additive
+scaling results from a general one-to-one mapping between the mean
+probe-surface force and the friction due to phonon radiation, irrespective of
+the nature of the underlying pair interaction. In contrast, phonon damping is
+strongly nonadditive, and no such general relation exists. We show that for
+certain cases, the dissipation can even {\it decrease} with increasing surface
+area the probe interacts with. The above properties, which are rooted in the
+spatial correlations of surface fluctuations, are expected to have important
+consequences when interpreting experimental measurements, as well as scaling
+with system size.",2108.03025v3
+2021-09-14,Design of a HOM-Damped 166.6 MHz Compact Quarter-Wave beta=1 Superconducting Cavity for High Energy Photon Source,"Superconducting cavities with low RF frequencies and heavy damping of higher
+order modes (HOM) are desired for the main accelerator of High Energy Photon
+Source (HEPS), a 6 GeV synchrotron light source promising ultralow emittance
+currently under construction in Beijing. A compact 166.6 MHz superconducting
+cavity was proposed adopting a quarter-wave beta=1 geometry. Based on the
+successful development of a proof-of-principle cavity, a HOM-damped 166.6 MHz
+compact superconducting cavity was subsequently designed. A ferrite damper was
+installed on the beam pipe to reduce HOM impedance below the stringent
+threshold of coupled-bunch instabilities. Being compact, RF field heating on
+the cavity vacuum seal was carefully examined against quenching the NbTi
+flange. The cavity was later dressed with a helium vessel and the tuning
+mechanism was also realized. Excellent RF and mechanical properties were
+eventually achieved. Finally, the two-cavity string was designed to ensure
+smooth transitions among components and proper shielding of synchrotron light.
+This paper presents a complete design of a fully dressed HOM-damped
+low-frequency beta=1 superconducting cavity for HEPS.",2109.06560v1
+2021-11-13,Effects of microplastics and surfactants on surface roughness of water waves,"In this paper, we study the flow physics underlying the recently developed
+remote sensing capability of detecting oceanic microplastics, which is based on
+the measurable surface roughness reduction induced by the presence of
+microplastics on the ocean surface. In particular, we are interested in whether
+this roughness reduction is caused by the microplastics as floating particles,
+or by the surfactants which follow similar transport paths as microplastics.
+For this purpose, we experimentally test the effects of floating particles and
+surfactants on surface roughness, quantified by the mean square slope (MSS),
+with waves generated by a mechanical wave maker or by wind. For microplastics,
+we find that their effect on wave energy and MSS critically depends on the
+surface area fraction of coverage, irrespective of the particle sizes in the
+test range. The damping by particles is observed only for fractions above
+$O(5-10\%)$, which is much higher than the realistic ocean condition. For
+surfactants, their damping effect on mechanically generated irregular waves
+generally increases with the concentration of surfactants, but no optimal
+concentration corresponding to maximum damping is observed, in contrast to
+previous studies based on monochromatic waves. In wind-wave experiments, the
+presence of surfactants suppresses the wave generation, due to the combined
+effects of reduced wind shear stress and increased wave damping. For the same
+wind speed, the wind stress is identified to depend on the concentration of
+surfactants with a power-law relation. The implications of these findings to
+remote sensing are discussed.",2111.07021v1
+2021-11-17,United Nation Security Council in Quantum World: Experimental Realization of Quantum Anonymous Veto Protocols using IBM Quantum Computer,"United Nation (UN) security council has fifteen members, out of which five
+permanent members of the council can use their veto power against any
+unfavorable decision taken by the council. In certain situation, a member using
+right to veto may prefer to remain anonymous. This need leads to the
+requirement of the protocols for anonymous veto which can be viewed as a
+special type of voting. Recently, a few protocols for quantum anonymous veto
+have been designed which clearly show quantum advantages in ensuring anonymity
+of the veto. However, none of the efficient protocols for quantum anonymous
+veto have yet been experimentally realized. Here, we implement 2 of those
+protocols for quantum anonymous veto using an IBM quantum computer named IBMQ
+Casablanca and different quantum resources like Bell, GHZ and cluster states.
+In this set of proof-of-principle experiments, it's observed that using the
+present technology, a protocol for quantum anonymous veto can be realized
+experimentally if the number of people who can veto remains small as in the
+case of UN council. Further, it's observed that Bell state based protocol
+implemented here performs better than the GHZ/cluster state based
+implementation of the other protocol in an ideal scenario as well as in
+presence of different types of noise (amplitude damping, phase damping,
+depolarizing and bit-flip noise). In addition, it's observed that based on
+diminishing impact on fidelity, different noise models studied here can be
+ordered in ascending order as phase damping, amplitude damping, depolarizing,
+bit-flip.",2111.09028v1
+2021-12-03,The Importance of Electron Landau Damping for the Dissipation of Turbulent Energy in Terrestrial Magnetosheath Plasma,"Heliospheric plasma turbulence plays a key role in transferring the energy of
+large-scale magnetic field and plasma flow fluctuations to smaller scales where
+the energy can be dissipated, ultimately leading to plasma heating.
+High-quality measurements of electromagnetic fields and electron velocity
+distributions by the Magnetospheric Multiscale (MMS) mission in Earth's
+magnetosheath present a unique opportunity to characterize plasma turbulence
+and to determine the mechanisms responsible for its dissipation. We apply the
+field-particle correlation technique to a set of twenty MMS magnetosheath
+intervals to identify the dissipation mechanism and quantify the dissipation
+rate. It is found that 95% of the intervals have velocity-space signatures of
+electron Landau damping that are quantitatively consistent with linear kinetic
+theory for the collisionless damping of kinetic Alfv\'en waves. About 75% of
+the intervals contain asymmetric signatures, indicating a local imbalance of
+kinetic Alfv\'en wave energy flux in one direction along the magnetic field
+than the other. About one third of the intervals have an electron energization
+rate with the same order-of-magnitude as the estimated turbulent cascade rate,
+suggesting that electron Landau damping plays a significant, and sometimes
+dominant, role in the dissipation of the turbulent energy in these
+magnetosheath intervals.",2112.02171v1
+2022-01-01,Extremely strong DLAs at high redshift: Gas cooling and H$_2$ formation,"We present a spectroscopic investigation with VLT/X-shooter of seven
+candidate extremely strong damped Lyman-$\alpha$ absorption systems (ESDLAs,
+$N(\text{HI})\ge 5\times 10^{21}$ cm$^{-2}$) observed along quasar sightlines.
+We confirm the extremely high column densities, albeit slightly (0.1~dex) lower
+than the original ESDLA definition for four systems. We measured low-ionisation
+metal abundances and dust extinction for all systems. For two systems we also
+found strong associated H$_2$ absorption $\log
+N(\text{H$_2$)[cm$^{-2}$]}=18.16\pm0.03$ and $19.28\pm0.06$ at $z=3.26$ and
+$2.25$ towards J2205+1021 and J2359+1354, respectively), while for the
+remaining five we measured conservative upper limits on the H$_2$ column
+densities of typically $\log N(\text{H$_2$)[cm$^{-2}$]}<17.3$. The increased
+H$_2$ detection rate ($10-55$% at 68% confidence level) at high HI column
+density compared to the overall damped Lyman-$\alpha$ population ($\sim 5-10$%)
+confirms previous works. We find that these seven ESDLAs have similar observed
+properties as those previously studied towards quasars and gamma-ray burst
+afterglows, suggesting they probe inner regions of galaxies. We use the
+abundance of ionised carbon in excited fine-structure level to calculate the
+cooling rates through the CII $\lambda$158$\mu$m emission, and compare them
+with the cooling rates from damped Lyman-$\alpha$ systems in the literature. We
+find that the cooling rates distribution of ESDLAs also presents the same
+bimodality as previously observed for the general (mostly lower HI column
+density) damped Lyman-$\alpha$ population.",2201.00245v1
+2022-01-05,Stability of the discrete time-crystalline order in spin-optomechanical and open cavity QED systems,"Discrete time crystals (DTC) have been demonstrated experimentally in several
+different quantum systems in the past few years. Spin couplings and cavity
+losses have been shown to play crucial roles for realizing DTC order in open
+many-body systems out of equilibrium. Recently, it has been proposed that
+eternal and transient DTC can be present with an open Floquet setup in the
+thermodynamic limit and in the deep quantum regime with few qubits,
+respectively. In this work, we consider the effects of spin damping and spin
+dephasing on the DTC order in spin-optomechanical and open cavity systems in
+which the spins can be all-to-all coupled. In the thermodynamic limit, it is
+shown that the existence of dephasing can destroy the coherence of the system
+and finally lead the system to its trivial steady state. Without dephasing,
+eternal DTC is displayed in the weak damping regime, which may be destroyed by
+increasing the all-to-all spin coupling or the spin damping. By contrast, the
+all-to-all coupling is constructive to the DTC in the moderate damping regime.
+We also focus on a model which can be experimentally realized by a suspended
+hexagonal boron nitride (hBN) membrane with a few spin color centers under
+microwave drive and Floquet magnetic field. Signatures of transient DTC
+behavior are demonstrated in both weak and moderate dissipation regimes without
+spin dephasing. Relevant experimental parameters are also discussed for
+realizing transient DTC order in such an hBN optomechanical system.",2201.01568v2
+2022-01-20,Sharp resolvent estimate for the Baouendi-Grushin operator and applications,"In this article we study the semiclassical resolvent estimate for the
+non-selfadjoint Baouendi-Grushin operator on the two-dimensional torus
+$\mathbb{T}^2=\mathbb{R}^2/(2\pi\mathbb{Z})^2$ with H\""older dampings. The
+operator is subelliptic degenerating along the vertical direction at $x=0$. We
+exhibit three different situations:
+  (i) the damping region verifies the geometric control condition with respect
+to both the non-degenerate Hamiltonian flow and the vertical subelliptic flow;
+  (ii) the undamped region contains a horizontal strip;
+  (iii) the undamped part is a line. In all of these situations, we obtain
+sharp resolvent estimates. Consequently, we prove the optimal energy decay rate
+for the associated damped waved equations. For (i) and (iii), our results are
+in sharp contrast to the Laplace resolvent since the optimal bound is governed
+by the quasimodes in the subelliptic regime. While for (ii), the optimality is
+governed by the quasimodes in the elliptic regime, and the optimal energy decay
+rate is the same as for the classical damped wave equation on $\mathbb{T}^2$.
+  Our analysis contains the study of adapted two-microlocal semiclassical
+measures, construction of quasimodes and refined Birkhoff normal-form
+reductions in different regions of the phase-space. Of independent interest, we
+also obtain the propagation theorem for semiclassical measures of quasimodes
+microlocalized in the subelliptic regime.",2201.08189v2
+2022-02-24,Coherence of ion cyclotron resonance for damping ion cyclotron waves in space plasmas,"Ion cyclotron resonance is one of the fundamental energy conversion processes
+through field-particle interaction in collisionless plasmas. However, the key
+evidence for ion cyclotron resonance (i.e., the coherence between
+electromagnetic fields and the ion phase space density) and the resulting
+damping of ion cyclotron waves (ICWs) has not yet been directly observed.
+Investigating the high-quality measurements of space plasmas by the
+Magnetospheric Multiscale (MMS) satellites, we find that both the wave
+electromagnetic field vectors and the bulk velocity of the disturbed ion
+velocity distribution rotate around the background magnetic field. Moreover, we
+find that the absolute gyro-phase angle difference between the center of the
+fluctuations in the ion velocity distribution functions and the wave electric
+field vectors falls in the range of (0, 90) degrees, consistent with the
+ongoing energy conversion from wave-fields to particles. By invoking plasma
+kinetic theory, we demonstrate that the field-particle correlation for the
+damping ion cyclotron waves in our theoretical model matches well with our
+observations. Furthermore, the wave electric field vectors ($\delta
+\mathbf{E'}_{\mathrm {wave,\perp}}$), the ion current density ($\delta
+\mathbf{J}_\mathrm {i,\perp}$) and the energy transfer rate ($\delta
+\mathbf{J}_\mathrm {i,\perp}\cdot \delta \mathbf{E'}_{\mathrm {wave,\perp}}$)
+exhibit quasi-periodic oscillations, and the integrated work done by the
+electromagnetic field on the ions are positive, indicates that ions are mainly
+energized by the perpendicular component of the electric field via cyclotron
+resonance. Therefore, our combined analysis of MMS observations and kinetic
+theory provides direct, thorough, and comprehensive evidence for ICW damping in
+space plasmas.",2202.11967v1
+2022-03-15,Search for gamma-ray line signals around the black hole at the galactic center with DAMPE observation,"The adiabatic growth of a black hole (BH) may enhance the dark matter (DM)
+density surrounding it, causing a spike in the DM density profile. The spike
+around the supermassive BH at the center of the Milky Way may lead to a
+dramatic enhancement of the gamma-ray flux of DM annihilation from the galactic
+center (GC). In this work, we analyze the gamma-ray data of the innermost
+region (i.e., the inner 1$^\circ$) of the GC to search for potential line-like
+signals from the BH spike. Such line-like signals could be generated in the
+process of DM particles annihilating into double photons. We adopt the
+gamma-ray data from the Dark Matter Particle Explorer (DAMPE). Although the
+DAMPE has a much smaller effective area than the Fermi-LAT, the gamma-ray line
+search can benefit from its unprecedented high energy resolution. No
+significant line-like signals are found in our analysis. We derive upper limits
+on the cross section of the annihilation based on this non-detection. We find
+that despite the DAMPE's small effective area for photon detection, we can
+still place strong constraints on the cross section ($\left<\sigma
+v\right>\lesssim10^{-27}\,{\rm cm^3\,s^{-1}}$) in the spike scenario due to the
+very bright model-expected flux from the spike. Our results indicate that
+either DM does not annihilate primarily through the $\gamma\gamma$ channel in
+the mass range we considered or no sharp density spike is present at the GC.",2203.08078v1
+2022-03-15,Optimal Damping with Hierarchical Adaptive Quadrature for Efficient Fourier Pricing of Multi-Asset Options in Lévy Models,"Efficiently pricing multi-asset options is a challenging problem in
+quantitative finance. When the characteristic function is available,
+Fourier-based methods are competitive compared to alternative techniques
+because the integrand in the frequency space often has a higher regularity than
+that in the physical space. However, when designing a numerical quadrature
+method for most Fourier pricing approaches, two key aspects affecting the
+numerical complexity should be carefully considered: (i) the choice of damping
+parameters that ensure integrability and control the regularity class of the
+integrand and (ii) the effective treatment of high dimensionality. We propose
+an efficient numerical method for pricing European multi-asset options based on
+two complementary ideas to address these challenges. First, we smooth the
+Fourier integrand via an optimized choice of the damping parameters based on a
+proposed optimization rule. Second, we employ sparsification and
+dimension-adaptivity techniques to accelerate the convergence of the quadrature
+in high dimensions. The extensive numerical study on basket and rainbow options
+under the multivariate geometric Brownian motion and some L\'evy models
+demonstrates the advantages of adaptivity and the damping rule on the numerical
+complexity of quadrature methods. Moreover, for the tested two-asset examples,
+the proposed approach outperforms the COS method in terms of computational
+time. Finally, we show significant speed-up compared to the Monte Carlo method
+for up to six dimensions.",2203.08196v4
+2022-03-25,Nonlinear damped spatially periodic breathers and the emergence of soliton-like rogue waves,"The spatially periodic breather solutions (SPBs) of the nonlinear
+Schr\""odinger equation, prominent in modeling rogue waves, are unstable. In
+this paper we numerically investigate the effects of nonlinear dissipation and
+higher order nonlinearities on the routes to stability of the SPBs in the
+framework of the nonlinear damped higher order nonlinear Schr\""odinger
+(NLD-HONLS) equation. The initial data used in the experiments are generated by
+evaluating exact SPB solutions at time $T_0$. The number of instabilities of
+the background Stokes wave and the damping strength are varied. The Floquet
+spectral theory of the NLS equation is used to interpret and provide a
+characterization of the perturbed dynamics in terms of nearby solutions of the
+NLS equation. Significantly, as $T_0$ is varied, tiny bands of complex spectrum
+are observed to pinch off in the Floquet decomposition of the NLD-HONLS data,
+reflecting the breakup of the SPB into a waveform that is close to either a one
+or two ""soliton-like"" structure. For wide ranges of $T_0$, i.e. for solutions
+initialized in the early to middle stage of the development of the MI, all
+rogue waves are observed to occur when the spectrum is close to a one or two
+soliton-like state. When the solutions are initialized as the MI is saturating,
+rogue waves also can occur after the spectrum has left a soliton-like state.
+Other novel features arise due to nonlinear damping: enhanced asymmetry, two
+timescales in the evolution of the spectrum and a delay in the growth of
+instabilities due to frequency downshifting.",2203.13488v2
+2022-03-25,Investigating the effect of noise channels on the quality of unitary t-designs,"Unitary t-designs have a wide variety of applications in quantum information
+theory, such as quantum data encryption and randomised benchmarking. However,
+experimental realisations of t-designs are subject to noise. Here we
+investigate the effect of noise channels on the quality of single-qubit
+t-designs. The noise channels we study are bit flips, phase flips, bit and
+phase flips, phase damping, amplitude damping, and depolarising noise. We
+consider two noise models: the first has noise applied before the t-design
+unitary operations, while the second has noise applied after the unitary
+operations. We show that the single-qubit 1-design is affected only by
+amplitude damping, while numeric results obtained for the 2-, 3-, 4-, and
+5-designs suggest that a 2t-design is significantly more sensitive to noise
+than a (2t-1)-design and that, with the exception of amplitude damping, a
+(2t+1)-design is as sensitive to noise as a 2t-design. Numeric results also
+reveal substantial variations in sensitivity to noise throughout the Bloch
+sphere. In particular, t-designs appear to be most sensitive to noise when
+acting on pure states and least sensitive to noise for the maximally mixed
+state. For depolarising noise, we show that our two noise models are
+equivalent, and for the other noise channels, numeric results obtained for the
+model where noise is applied after the unitaries reflect the transformation of
+the noise channel into a depolarising channel, an effect exploited in
+randomised benchmarking with 2-designs.",2203.13771v2
+2022-04-25,Geometrical aspects of contact mechanical systems and field theories,"Many important theories in modern physics can be stated using differential
+geometry. Symplectic geometry is the natural framework to deal with autonomous
+Hamiltonian mechanics. This admits several generalizations for nonautonomous
+systems, both regular and singular. Some of these extensions are the subject of
+this thesis.
+  Recently there has been a growing interest in studying dissipative mechanical
+systems from a geometric perspective using contact geometry. In this thesis we
+review what has been done in this topic and go deeper, studying symmetries and
+dissipated quantities of contact systems, and developing the Skinner-Rusk
+formalism for these systems.
+  With regard to classical field theory, we introduce the notion of
+k-precosymplectic manifold and use it to give a geometric description of
+singular nonautonomous field theories. We also devise a constraint algorithm
+for these systems.
+  Field theories with damping are described through a modification of the De
+Donder-Weyl Hamiltonian field theory. This is achieved by combining contact
+geometry and k-symplectic structures, resulting in the k-contact formalism. We
+introduce two notions of dissipation laws, generalizing the concept of
+dissipated quantity. These developments are also applied to Lagrangian field
+theory. The Skinner-Rusk formulation for k-contact systems is described in
+detail and we show how to recover the Lagrangian and Hamiltonian formalisms
+from it.
+  Throughout the thesis we present several examples in mechanics and field
+theory. The most remarkable mechanical examples are the damped harmonic
+oscillator, the motion in a gravitational field with friction, the parachute
+equation and the damped simple pendulum. In field theory, we study the damped
+vibrating string, the Burgers' equation, the Klein-Gordon equation and its
+relation with the telegrapher's equation, and the Maxwell's equations with
+dissipation.",2204.11537v1
+2022-06-20,Swinging a playground swing: torque controls for inducing sustained oscillations,"Models of a playground swing have been studied since the 1960s. However, in
+most of them, the position of the swinger is controlled directly. This
+simplifies the problem but hides the mechanics of torques applied to keep the
+swing moving in a regular pattern. This article studies these mechanics. Two
+models of a swing with torques as controls that we consider are identical to
+popular models of modern robotics: the Acrobot and reaction wheel pendulum.
+However, the control task of sustaining the swing's regular oscillations by a
+static feedback control is new and challenging, especially when damping in the
+joint connecting the swing to the frame is considered. We develop two types of
+controls to accomplish this task. One works for small damping and is based on
+linearizing the undamped system by a suitable preliminary feedback control. The
+other works for large damping. In the steady state, the resulting closed-loop
+system describes a harmonically driven damped pendulum (a simple system known
+for its complex behavior), including chaotic motion for some parameter values.
+To address such complexities, we build free parameters into the controls, then
+adjust them based on simulations to avoid chaos and achieve regular
+oscillations that are seen on playgrounds.",2206.09579v1
+2022-07-01,Frequency beating and damping of breathing oscillations of a harmonically trapped one-dimensional quasicondensate,"We study the breathing (monopole) oscillations and their damping in a
+harmonically trapped one-dimensional (1D) Bose gas in the quasicondensate
+regime using a finite-temperature classical field approach. By characterising
+the oscillations via the dynamics of the density profile's rms width over long
+time, we find that the rms width displays beating of two distinct frequencies.
+This means that 1D Bose gas oscillates not at a single breathing mode
+frequency, as found in previous studies, but as a superposition of two distinct
+breathing modes, one oscillating at frequency close to $\simeq\!\sqrt{3}\omega$
+and the other at $\simeq\!2\omega$, where $\omega$ is the trap frequency. The
+breathing mode at $\sim\!\sqrt{3}\omega$ dominates the beating at lower
+temperatures, deep in the quasicondensate regime, and can be attributed to the
+oscillations of the bulk of the density distribution comprised of particles
+populating low-energy, highly-occupied states. The breathing mode at
+$\simeq\!2\omega$, on the other hand, dominates the beating at higher
+temperatures, close to the nearly ideal, degenerate Bose gas regime, and is
+attributed to the oscillations of the tails of the density distribution
+comprised of thermal particles in higher energy states. The two breathing modes
+have distinct damping rates, with the damping rate of the bulk component being
+approximately four times larger than that of the tails component.",2207.00209v2
+2022-07-29,Coordinated control in multi-terminal VSC-HVDC systems to improve transient stability: Impact on electromechanical-oscillation damping,"Multi-terminal high-voltage Direct Current technology based on Voltage-Source
+Converter stations (VSC-MTDC) is expected to be one of the most important
+contributors to the future of electric power systems. In fact, among other
+features, it has already been shown how this technology can contribute to
+improve transient stability in power systems by the use of supplementary
+controllers. Along this line, this paper will investigate in detail how these
+supplementary controllers may affect electromechanical oscillations, by means
+of small-signal stability analysis. The paper analyses two control strategies
+based on the modulation of active-power injections (P-WAF) and reactive-power
+injections (Q-WAF) in the VSC stations. Both control strategies use global
+signals of the frequencies of the VSC-MTDC system and they presented
+significant improvements on transient stability. The paper will provide
+guidelines for the design of these type of controllers to improve both, large-
+and small-disturbance angle stability. Small-signal stability techniques (in
+Matlab) will be used to assess electromechanical-oscillation damping, while
+non-linear time domain simulation (in PSS/E) will be used to confirm the
+results. Results will be illustrated in Nordic32A test system with an embedded
+VSC-MTDC system. The paper analyses the impact of the controller gains and
+communication latency on electromechanical-oscillation damping. The main
+conclusion of the paper is that transient-stability-tailored supplementary
+controllers in VSC-MTDC systems can be tuned to damp inter-area oscillations
+too, maintaining their effectiveness for transient-stability improvement.",2208.00083v1
+2022-08-04,Thermoelastic Damping in MEMS Gyroscopes at High Frequencies,"Microelectromechanical systems (MEMS) gyroscopes are widely used, e.g. in
+modern automotive and consumer applications, and require signal stability and
+accuracy in rather harsh environmental conditions. In many use cases, device
+reliability must be guaranteed under large external loads at high frequencies.
+The sensitivity of the sensor to such external loads depends strongly on the
+damping, or rather quality factor, of the high frequency mechanical modes of
+the structure. In this paper, we investigate the influence of thermoelastic
+damping on several high frequency modes by comparing finite element simulations
+with measurements of the quality factor in an application-relevant temperature
+range. We measure the quality factors over different temperatures in vacuum, to
+extract the relevant thermoelastic material parameters of the polycrystalline
+MEMS device. Our simulation results show a good agreement with the measured
+quantities, therefore proving the applicability of our method for predictive
+purposes in the MEMS design process. Overall, we are able to uniquely identify
+the thermoelastic effects and show their significance for the damping of the
+high frequency modes of an industrial MEMS gyroscope. Our approach is generic
+and therefore easily applicable to any mechanical structure with many possible
+applications in nano- and micromechanical systems.",2208.02591v2
+2022-08-02,Motion of a parametrically driven damped coplanar double pendulum,"We present the results of linear stability of a damped coplanar double
+pendulum and its non-linear motion, when the point of suspension is vibrated
+sinusoidally in the vertical direction with amplitude $a$ and frequency $\omega
+$. A double pendulum has two pairs of Floquet multipliers, which have been
+calculated for various driving parameters. We have considered the stability of
+a double pendulum when it is in any of its possible stationary states: (i) both
+pendulums are either vertically downward or upward and (ii) one pendulum is
+downward, and the other is upward. The damping is considered to be
+velocity-dependent, and the driving frequency is taken in a wide range. A
+double pendulum excited from its stable state shows both periodic and chaotic
+motion. The periodic motion about its pivot may be either oscillatory or
+rotational. The periodic swings of a driven double pendulum may be either
+harmonic or subharmonic for lower values of $a$. The limit cycles corresponding
+to the normal mode oscillations of a double pendulum of two equal masses are
+squeezed into a line in its configuration space. For unequal masses, the
+pendulum shows multi-period swings for smaller values of $a$ and damping, while
+chaotic swings or rotational motion at relatively higher values of $a$. The
+parametric driving may lead to stabilization of a partially or fully inverted
+double pendulum.",2208.03292v2
+2022-08-09,Simultaneous measurements of unstable and stable Alfvén Eigenmodes in JET,"In this paper, we report the novel experimental observation of both unstable
+and stable Toroidicity-induced Alfv\'en Eigenmodes (TAEs) measured
+simultaneously in a JET tokamak plasma. The three-ion-heating scheme
+(D-DNBI-3He) is employed to accelerate deuterons to MeV energies, thereby
+destabilizing TAEs with toroidal mode numbers n = 3-5, each decreasing in mode
+amplitude. At the same time, the Alfv\'en Eigenmode Active Diagnostic
+resonantly excites a stable n = 6 TAE with total normalized damping rate
+$-\gamma/\omega_0 \approx$ 1%-4%. Hybrid kinetic-MHD modeling with codes NOVA-K
+and MEGA both find eigenmodes with similar frequencies, mode structures, and
+radial locations as in experiment. NOVA-K demonstrates good agreement with the
+n = 3, 4, and 6 TAEs, matching the damping rate of the n = 6 mode within
+uncertainties and identifying radiative damping as the dominant contribution.
+Improved agreement is found with MEGA for all modes: the unstable n = 3-5 and
+stable n = 2, 6 modes, with the latter two stabilized by higher intrinsic
+damping and lower fast ion drive, respectively. While some discrepancies remain
+to be resolved, this unique validation effort gives us confidence in TAE
+stability predictions for future fusion devices.",2208.05052v1
+2022-09-24,Deep Attentive Belief Propagation: Integrating Reasoning and Learning for Solving Constraint Optimization Problems,"Belief Propagation (BP) is an important message-passing algorithm for various
+reasoning tasks over graphical models, including solving the Constraint
+Optimization Problems (COPs). It has been shown that BP can achieve
+state-of-the-art performance on various benchmarks by mixing old and new
+messages before sending the new one, i.e., damping. However, existing methods
+of tuning a static damping factor for BP not only are laborious but also harm
+their performance. Moreover, existing BP algorithms treat each variable node's
+neighbors equally when composing a new message, which also limits their
+exploration ability. To address these issues, we seamlessly integrate BP, Gated
+Recurrent Units (GRUs), and Graph Attention Networks (GATs) within the
+message-passing framework to reason about dynamic weights and damping factors
+for composing new BP messages. Our model, Deep Attentive Belief Propagation
+(DABP), takes the factor graph and the BP messages in each iteration as the
+input and infers the optimal weights and damping factors through GRUs and GATs,
+followed by a multi-head attention layer. Furthermore, unlike existing
+neural-based BP variants, we propose a novel self-supervised learning algorithm
+for DABP with a smoothed solution cost, which does not require expensive
+training labels and also avoids the common out-of-distribution issue through
+efficient online learning. Extensive experiments show that our model
+significantly outperforms state-of-the-art baselines.",2209.12000v1
+2022-12-01,Slack-based tunable damping leads to a trade-off between robustness and efficiency in legged locomotion,"Animals run robustly in diverse terrain. This locomotion robustness is
+puzzling because axon conduction velocity is limited to a few ten meters per
+second. If reflex loops deliver sensory information with significant delays,
+one would expect a destabilizing effect on sensorimotor control. Hence, an
+alternative explanation describes a hierarchical structure of low-level
+adaptive mechanics and high-level sensorimotor control to help mitigate the
+effects of transmission delays. Motivated by the concept of an adaptive
+mechanism triggering an immediate response, we developed a tunable physical
+damper system. Our mechanism combines a tendon with adjustable slackness
+connected to a physical damper. The slack damper allows adjustment of damping
+force, onset timing, effective stroke, and energy dissipation. We characterize
+the slack damper mechanism mounted to a legged robot controlled in open-loop
+mode. The robot hops vertically and planar over varying terrains and
+perturbations. During forward hopping, slack-based damping improves faster
+perturbation recovery (up to 170%) at higher energetic cost (27%). The tunable
+slack mechanism auto-engages the damper during perturbations, leading to a
+perturbation-trigger damping, improving robustness at minimum energetic cost.
+With the results from the slack damper mechanism, we propose a new functional
+interpretation of animals' redundant muscle tendons as tunable dampers.",2212.00475v1
+2023-01-19,Magnetoreological spring as element of vibration control system of dynamicly active equipment for biofuel production,"The development of vibration protection systems that ensure efficiency and
+safety in the operation of process equipment and pipelines is one of the main
+tasks of controlling the dynamic state of machines. One of the effective
+methods of vibration isolation of the equipment of these installations is the
+use of vibration mounts. Today, both passive and active methods of
+extinguishing are actively used. The combination of two methods of damping will
+ensure the stability and adaptability of vibration protection systems to the
+operating conditions of process equipment. The paper presents and investigates
+the device of a hybrid vibration support, including a magnetorheological
+spring, as an element of vibration damping. A distinctive feature of the
+vibration mount is an extended range of performance and reduced wear rate of
+the components. An analysis of the damping characteristics of a hybrid
+vibration support in passive and active modes of operation is presented. A
+simulation model of the vibration support under consideration has been
+developed in the MATLAB Simulink simulation environment using the PIB
+controller. The simulation results indicate the effectiveness of the use of
+vibration damping systems with a magnetorheological spring in conjunction with
+various technological equipment.",2301.07911v1
+2023-02-19,Collective Quantum Approach to Surface Plasmon Resonance Effect,"In this research we present a theory of the surface plasmon resonance (SPR)
+effect based on the dual length-scale driven damped collective quantum
+oscillations of the spill-out electrons in plasmonic material surface. The
+metallic electron excitations are modeled using the Hermitian effective
+Schr\""{o}dinger-Poisson system, whereas, the spill-out electron excitations are
+modeled via the damped non-Hermitian effective Schr\""{o}dinger-Poisson system
+adapted appropriately at the metal-vacuum interface. It is shows that, when
+driven by external field, the system behaves like the driven damped oscillator
+in wavenumber domain, quite analogous to the driven damped mechanical
+oscillation in frequency domain, leading to the collective surface spill-out
+electron excitation resonance. In this model the resonance occurs when the
+wavenumber of the driving pseudoforce matches that of the surface plasmon
+excitations which can be either due to single-electrons or collective effects.
+Current theory of SPR is based on longitudinal electrostatic excitations of the
+surface electrons, instead of the polariton excitation parallel to the
+metal-dielectric or metal-vacuum surface. Current theory may also be extended
+to use for the localized surface plasmon resonance (LSPR) in nanometer sized
+metallic surfaces in non-planar geometry. A new equation of state (EoS) for the
+plasmon electron number density in quantum plasmas is obtained which limits the
+plasmonic effects in high-density low-temperature electron gas regime, due to
+small transition probability of electrons to the plasmon energy band.",2302.13974v1
+2023-03-01,Evolution of the eccentricity and inclination of low-mass planets subjected to thermal forces: a numerical study,"By means of three dimensional, high resolution hydrodynamical simulations we
+study the orbital evolution of weakly eccentric or inclined low-mass
+protoplanets embedded in gaseous discs subject to thermal diffusion. We
+consider both non-luminous planets, and planets that also experience the
+radiative feedback from their own luminosity. We compare our results to
+previous analytical work, and find that thermal forces (the contribution to the
+disc's force arising from thermal effects) match those predicted by linear
+theory within $\sim 20$%. When the planet's luminosity exceeds a threshold
+found to be within $10$% of that predicted by linear theory, its eccentricity
+and inclination grow exponentially, whereas these quantities undergo a strong
+damping below this threshold. In this regime of low luminosity indeed, thermal
+diffusion cools the surroundings of the planet and allows gas to accumulate in
+its vicinity. It is the dynamics of this gas excess that contributes to damp
+eccentricity and inclination. The damping rates obtained can be up to $h^{-1}$
+times larger than those due to the resonant interaction with the disc, where
+$h$ is the disc's aspect ratio. This suggests that models that incorporate
+planet-disc interactions using well-known formulae based on resonant
+wave-launching to describe the evolution of eccentricity and inclination
+underestimate the damping action of the disc on the eccentricity and
+inclination of low-mass planets by an order of magnitude.",2303.00867v1
+2023-03-13,Discriminative sEMG-based features to assess damping ability and interpret activation patterns in lower-limb muscles of ACLR athletes,"Objective: The main goal of the athletes who undergo anterior cruciate
+ligament reconstruction (ACLR) surgery is a successful return-to-sport. At this
+stage, identifying muscular deficits becomes important. Hence, in this study,
+three discriminative features based on surface electromyographic signals (sEMG)
+acquired in a dynamic protocol are introduced to assess the damping ability and
+interpret activation patterns in lower-limb muscles of ACLR athletes. Methods:
+The features include the median frequency of the power spectrum density (PSD),
+the relative percentage of the equivalent damping or equivalent stiffness
+derived from the median frequency, and the energy of the signals in the
+time-frequency plane of the pseudo-Wigner-Ville distribution (PWVD). To
+evaluate the features, 11 healthy and 11 ACLR athletes (6 months
+post-reconstruction surgery) were recruited to acquire the sEMG signals from
+the medial and the lateral parts of the hamstrings, quadriceps, and
+gastrocnemius muscles in pre- and post-fatigue single-leg landings. Results: A
+significant damping deficiency is observed in the hamstring muscles of ACLR
+athletes by evaluating the proposed features. This deficiency indicates that
+more attention should be paid to this muscle of ACLR athletes in
+pre-return-to-sport rehabilitations. Conclusion: The quality of
+electromyography-based pre-return-to-sport assessments on ACLR subjects depends
+on the sEMG acquisition protocol, as well as the type and nature of the
+extracted features. Hence, combinatorial application of both energy-based
+features (derived from the PWVD) and power-based features (derived from the
+PSD) could facilitate the assessment process by providing additional
+biomechanical information regarding the behavior of the muscles surrounding the
+knee.",2303.06954v1
+2023-03-28,Search for damped oscillating structures from charged pion electromagnetic form factor data,"The damped oscillating structures recently revealed by a three parametric
+formula from the proton ``effective'' form factor data extracted of the
+measured total cross section $\sigma^{bare}_{tot}(e^+e^-\to p\bar p)$ still
+seem to have an unknown origin. The conjectures of their direct manifestation
+of the quark-gluon structure of the proton indicate that they are not specific
+only of the proton and neutron, but they have to be one's own, similar to other
+hadrons.
+  Therefore, the oscillatory structures from the charged pion electromagnetic
+form factor timelike data, extracted of the process $e^+e^-\to \pi^+ \pi^-$ are
+investigated by using the same procedure as in the case of the proton.
+  The analysis shows the appearance of the oscillating structures in the
+description of the charged pion electromagnetic form factor timelike data by
+three parametric formula with a rather large value of $\chi^2/ndf$, while the
+description of the data by the physically well-founded Unitary and Analytic
+model has not revealed any damped oscillating structures.
+  From the obtained result on the most simple object of strong interactions,
+one can conclude that damped oscillating structures received from the
+``effective'' proton form factor data are probably generated by a utilization
+of the improper three parametric formula which does not describe these data
+with sufficient precision.",2303.16681v1
+2023-05-15,Landau damping and the survival threshold,"In this paper, we establish the large time asymptotic behavior of solutions
+to the linearized Vlasov-Poisson system near general spatially homogenous
+equilibria $\mu(\frac12|v|^2)$ with connected support on the whole space
+$\RR^3_x \times \RR^3_v$, including those that are non-monotone. The problem
+can be solved completely mode by mode for each spatial wave number, and their
+longtime dynamics is intimately tied to the ``survival threshold'' of wave
+numbers computed by $$\kappa_0^2 = 4\pi \int_0^\Upsilon \frac{u^2\mu(\frac12
+u^2)}{\Upsilon^2-u^2} \;du$$ where $\Upsilon$ is the maximal speed of particle
+velocities. It is shown that purely oscillatory electric fields exist and obey
+a Klein-Gordon's type dispersion relation for wave numbers below the threshold,
+thus confirming the existence of Langmuir's oscillatory waves known in the
+physical literature. At the threshold, the phase velocity of these oscillatory
+waves enters the range of admissible particle velocities, namely there are
+particles that move at the same propagation speed of the waves. It is this
+exact resonant interaction between particles and the oscillatory fields that
+causes the waves to be damped, classically known as Landau damping. Landau's
+law of decay is explicitly computed and is sensitive to the decaying rate of
+the background equilibria. The faster it decays at the maximal velocity, the
+weaker Landau damping is. Beyond the threshold, the electric fields are a
+perturbation of those generated by the free transport dynamics and thus decay
+rapidly fast due to the phase mixing mechanism.",2305.08672v1
+2023-06-04,Large Dynamical Tide Amplitudes from Small Kicks at Pericenter,"The effect of dynamical tide ``kicks"" on eccentric binary orbits is
+considered using the orbital mapping method. It is demonstrated that when mode
+damping is negligible the mode amplitude will generically grow in time for all
+values of orbital eccentricity and semi-major axis, even for small kicks
+outside the regime exhibiting diffusive growth. The origin of the small-kick
+growth is the change in kick size from orbit to orbit, an effect quadratic in
+the mode amplitude. When damping of the mode is included, the growth is shut
+off when the damping time is shorter than the growth time. Hence, in practice,
+kicks of sufficient size and long mode damping times are required for
+interesting levels of growth to occur. Application to the circularization of
+hot Jupiters is discussed. Previous investigations found that diffusive growth
+of the planetary f-mode in the large-kick regime would lead to rapid orbital
+shrinkage, but upon exiting the diffusive regime at $e \sim 0.9$ the theory
+would predict a large population of highly eccentric orbits. Simulations
+presented here show that subsequent orbital evolution relying on the small-kick
+regime may further decrease the eccentricity to $e \sim 0.2$ on timescales much
+less than the Gyrs ages of these systems.",2306.02382v1
+2023-06-16,Damping of MHD Turbulence in A Partially Ionized Medium,"The coupling state between ions and neutrals in the interstellar medium plays
+a key role in the dynamics of magnetohydrodynamic (MHD) turbulence, but is
+challenging to study numerically. In this work, we investigate the damping of
+MHD turbulence in a partially ionized medium using 3D two-fluid (ions+neutrals)
+simulations generated with the AthenaK code. Specifically, we examine the
+velocity, density, and magnetic field statistics of the two-fluid MHD
+turbulence in different regimes of neutral-ion coupling. Our results
+demonstrate that when ions and neutrals are strongly coupled, the velocity
+statistics resemble those of single-fluid MHD turbulence. Both the velocity
+structures and kinetic energy spectra of ions and neutrals are similar, while
+their density structures can be significantly different. With an excess of
+small-scale sharp density fluctuations in ions, the density spectrum in ions is
+shallower than that of neutrals. When ions and neutrals are weakly coupled, the
+turbulence in ions is more severely damped due to the ion-neutral collisional
+friction than that in neutrals, resulting in a steep kinetic energy spectrum
+and density spectrum in ions compared to the Kolmogorov spectrum. We also find
+that the magnetic energy spectrum basically follows the shape of the kinetic
+energy spectrum of ions, irrespective of the coupling regime. In addition, we
+find large density fluctuations in ions and neutrals and thus spatially
+inhomogeneous ionization fractions. As a result, the neutral-ion decoupling and
+damping of MHD turbulence take place over a range of length scales.",2306.10010v2
+2023-07-24,BGO quenching effect on spectral measurements of cosmic-ray nuclei in DAMPE experiment,"The Dark Matter Particle Explorer (DAMPE) is a satellite-borne detector
+designed to measure high energy cosmic-rays and $\gamma$-rays. As a key
+sub-detector of DAMPE, the Bismuth Germanium Oxide (BGO) imaging calorimeter is
+utilized to measure the particle energy with a high resolution. The nonlinear
+fluorescence response of BGO for large ionization energy deposition, known as
+the quenching effect, results in an under-estimate of the energy measurement
+for cosmic-ray nuclei. In this paper, various models are employed to
+characterize the BGO quenching factors obtained from the experimental data of
+DAMPE. Applying the proper quenching model in the detector simulation process,
+we investigate the tuned energy responses for various nuclei and compare the
+results based on two different simulation softwares, i.e. GEANT4 and FLUKA. The
+BGO quenching effect results in a decrease of the measured energy by
+approximately $2.5\%$ ($5.7 \%$) for carbon (iron) at $\sim$10 GeV/n and $<1\%$
+above 1 TeV/n, respectively. Accordingly, the correction of the BGO quenching
+effect leads to an increase of the low-energy flux measurement of cosmic-ray
+nuclei.",2307.12629v1
+2023-08-04,"Interplay of space charge, intrabeam scattering and synchrotron radiation in the Compact Linear Collider damping rings","Future ultra-low emittance rings for electron/positron colliders requiring
+extremely high beam brightness can be limited by collective effects. In this
+paper, the interplay of effects such as synchrotron radiation, intra-beam
+scattering (IBS) and space charge in the vicinity of excited betatron
+resonances is assessed. In this respect, two algorithms were developed to
+simulate IBS and synchrotron radiation effects and integrated in the PyORBIT
+tracking code, to be combined with its widely used space charge module. The
+impact of these effects on the achievable beam parameters of the Compact Linear
+Collider (CLIC) Damping Rings was studied, showing that synchrotron radiation
+damping mitigates the adverse effects of IBS and space charge induced resonance
+crossing. The studies include also a full dynamic simulation of the CLIC
+damping ring cycle starting from the injection beam parameters. It is
+demonstrated that a careful working point choice is necessary, in order to
+accommodate the transition from a non-linear lattice induced detuning to a
+space-charge dominated one and thereby avoid excessive losses and emittance
+growth generated in the vicinity of strong resonances.",2308.02196v3
+2023-08-04,Nonlinear wave damping by Kelvin-Helmholtz instability induced turbulence,"Magnetohydrodynamic kink waves naturally form as a consequence of
+perturbations to a structured medium, for example transverse oscillations of
+coronal loops. Linear theory has provided many insights in the evolution of
+linear oscillations, and results from these models are often applied to infer
+information about the solar corona from observed wave periods and damping
+times. However, simulations show that nonlinear kink waves can host the
+Kelvin-Helmholtz instability (KHi) which subsequently creates turbulence in the
+loop, dynamics which are beyond linear models. In this paper we investigate the
+evolution of KHi-induced turbulence on the surface of a flux tube where a
+non-linear fundamental kink-mode has been excited. We control our numerical
+experiment so that we induce the KHi without exciting resonant absorption. We
+find two stages in the KHi turbulence dynamics. In the first stage, we show
+that the classic model of a KHi turbulent layer growing $\propto t$is
+applicable. We adapt this model to make accurate predictions for damping of the
+oscillation and turbulent heating as a consequence of the KHi dynamics. In the
+second stage, the now dominant turbulent motions are undergoing decay. We find
+that the classic model of energy decay proportional to $t^{-2}$ approximately
+holds and provides an accurate prediction of the heating in this phase. Our
+results show that we can develop simple models for the turbulent evolution of a
+non-linear kink wave, but the damping profiles produced are distinct from those
+of linear theory that are commonly used to confront theory and observations.",2308.02217v2
+2023-08-10,JWST observations of galaxy damping wings during reionization interpreted with cosmological simulations,"Spectra of the highest redshift galaxies taken with JWST are now allowing us
+to see into the heart of the reionization epoch. Many of these observed
+galaxies exhibit strong damping wing absorption redward of their Lyman-$\alpha$
+emission. These observations have been used to measure the redshift evolution
+of the neutral fraction of the intergalactic medium and sizes of ionized
+bubbles. However, these estimates have been made using a simple analytic model
+for the intergalactic damping wing. We explore the recent observations with
+models of inhomogeneous reionization from the Sherwood-Relics simulation suite.
+We carry out a comparison between the damping wings calculated from the
+simulations and from the analytic model. We find that although the agreement is
+good on the red side of the Lyman-$\alpha$ emission, there is a discrepancy on
+the blue side due to residual neutral hydrogen present in the simulations,
+which saturates the intergalactic absorption. For this reason, we find that it
+is difficult to reproduce the claimed observations of large bubble sizes at z ~
+7, which are driven by a detection of transmitted flux blueward of the
+Lyman-$\alpha$ emission. We suggest instead that the observations can be
+explained by a model with smaller ionized bubbles and larger intrinsic
+Lyman-$\alpha$ emission from the host galaxy.",2308.05800v1
+2023-08-23,Dynamics of pinned quantized vortices in superfluid $^4$He in a microelectromechanical oscillator,"We numerically studied the vortex dynamics at zero temperature in superfluid
+$^4$He confined between two parallel rough solid boundaries, one of which
+oscillates in a shear mode. This study was motivated by the experimental work
+by Barquist $et$ $al.$ which employed a microelectromechanical systems (MEMS)
+oscillator operating in superfluid $^4$He at a near-zero temperature. Their
+experiments suggest that the motion of the MEMS oscillator is damped by
+quantized vortices. In our study, we postulated that this damping effect was
+closely associated with vortex pinning phenomena and developed pinning models.
+Our primary objective is to understand the vortex dynamics in the presence of
+pinning and to provide insight into the experimental observations regarding the
+damping mechanism. We confirmed that Kelvin waves were excited in the pinned
+vortices when the oscillation frequency of the solid boundary matched with the
+mode frequency of the Kelvin wave. Additionally, we examined the formation and
+evolution of vortex tangles between the boundaries. The vortex tangle was
+suppressed in the presence of pinning, while the absence of pinning allowed to
+form well developed vortex tangle resulting in turbulence. Finally, by
+evaluating the tension of pinned vortices we extracted the damping force acting
+on the solid boundaries.",2308.11942v2
+2023-12-29,Modeling polyelectrolyte hydration from a multi scale polarizable pseudo particle solvent coarse grained approach,"We investigate the reliability of simulations of polyelectrolyte systems in
+aqueous environments, simulations that are performed using an efficient multi
+scale coarse grained polarizable pseudo-particle particle approach, denoted as
+pppl, to model the solvent water, whereas the solutes are modeled using a
+polarizable all atom force field. We focus our study on issues tied to two key
+parameters of the pppl approach, namely the extension of the solvent domain SD
+at the close vicinity of a solute (domain in which each solvent particle
+corresponds to a single water molecule) and the magnitude of solute/solvent
+short range polarization damping effects. To this end we built a new pppl
+models from which we simulate NaCl aqueous solutions at the molar concentration
+scale. We also re investigate the hydration of a hydrophobic polyelectrolyte
+polymer that we showed in an earlier study [J Chem Phys, 114903 (155) 2021] to
+evolve towards a counter intuitive globular form surrounded by a spherical
+counter ion cloud along pppl-based simulations. Strong short range damping is
+pivotal to simulate NaCl aqueous solutions. The extension of the domain SD (as
+well as short range damping) has a weak effect on the conformation of the
+polymer, but it plays a pivotal role to compute accurate solute/solvent
+interaction energies. In all our results lead us to recommend to simulate
+polyelectrolyte polymers as dissolved alone in pppl fluids (i.e. without
+explicitly accounting for their counter ions) to investigate their behavior at
+infinite dilution conditions, and to systematically consider strong
+solute/solvent polarization short range damping to model charged species.",2312.17580v1
+2024-02-20,The Fundamental Parameters of Astrophysical Plasma Turbulence and its Dissipation: Nonrelativistic Limit,"A specific set of dimensionless plasma and turbulence parameters is
+introduced to characterize the nature of turbulence and its dissipation in
+weakly collisional space and astrophysical plasmas. Key considerations are
+discussed for the development of predictive models of the turbulent plasma
+heating that characterize the partitioning of dissipated turbulent energy
+between the ion and electron species and between the perpendicular and parallel
+degrees of freedom for each species. Identifying the kinetic physical
+mechanisms that govern the damping of the turbulent fluctuations is a critical
+first step in constructing such turbulent heating models. A set of ten general
+plasma and turbulence parameters are defined, and reasonable approximations
+along with the exploitation of existing scaling theories for
+magnetohydrodynamic turbulence are used to reduce this general set of ten
+parameters to just three parameters in the isotropic temperature case. A
+critical step forward in this study is to identify the dependence of all of the
+proposed kinetic mechanisms for turbulent damping in terms of the same set of
+fundamental plasma and turbulence parameters. Analytical estimations of the
+scaling of each damping mechanism on these fundamental parameters are
+presented, and this information is synthesized to produce the first phase
+diagram for the turbulent damping mechanisms as a function of driving scale and
+ion plasma beta.",2402.12829v1
+2024-03-06,Universality of pseudo-Goldstone damping near critical points,"Recently, in studies of holographic models and hydrodynamics with spontaneous
+breaking of approximate symmetries, it has been proposed that the damping of
+pseudo-Goldstone modes at finite temperatures is universally constrained in the
+way that $\Omega_{\varphi}/m_{\varphi}^2\simeq D_{\varphi}$ in the broken
+phase, where $\Omega_{\varphi}$ and $m_{\varphi} $ are the relaxation rate at
+zero wavenumber and the mass of pseudo-Goldstones, $D_{\varphi}$ is the
+Goldstone diffusivity in the limit of purely spontaneous breaking. In this
+paper, we investigate the pseudo-Goldstone damping in a purely relaxational
+O($N$) model by performing the functional renormalization group calculations at
+the full quantum and stochastic level within the Schwinger-Keldysh formalism.
+We find that, away from the critical temperature, the proposed relation is
+always valid. When the temperature is very close to the critical value such
+that the mass of the Higgs mode is comparable to the mass of the
+pseudo-Goldstone modes, the pseudo-Goldstone damping displays a novel scaling
+behavior that follows $\Omega_\varphi/m_\varphi^2\propto
+m_{\varphi}^{\Delta_\eta}$ with a correction $\Delta_\eta$ controlled by the
+critical universalities. Moreover, we study how the correction depends on the
+value of $N$ and show that $\Delta_\eta \rightarrow 0$ when fluctuations are
+infinitely suppressed in the large $N$ limit. In this case, the proposed
+relation works even in the critical region. Finally, we match our results to
+the dissipative sector of the pion dynamics near the chiral phase transition.",2403.03503v2
+1993-11-17,Early Reionization in Cosmology,"The cosmic microwave background (CMB) anisotropies have turned out to
+represent one of the most stringent 'bottle necks' for scenarios of large scale
+structure formation. As a possibility to relax this constraint, it has been
+proposed that early reionization can damp CMB fluctuations on small scales due
+to photon diffusion in the ionized plasma. As an example, I investigate the
+recently proposed scenario with cold dark matter (CDM) and texture seeds.
+There, an analysis of CMB anisotropies shows that early reionization is a
+crucial ingredient for this scenario. Without damping, the small scale
+anisotropies would dominate and exceed observed limits. In this paper I present
+analytical and numerical results for the amount of damping due to early
+reionization for CMB perturbations induced by a collapsing texture.
+Furthermore, the spectral distortion of the CMB due to Compton scattering of
+the hotter plasma electrons is calculated. Next I discuss the physical
+processes which lead to a system of coupled ordinary differential equations for
+the degree of ionization, the electron temperature and the evolution of the
+ionizing radiation.",9311039v1
+1994-08-18,The Damping and Excitation of Galactic Warps by Dynamical Friction,"We investigate the dynamical interaction of galactic warps with the
+surrounding dark matter halo, using analytic perturbation theory. A precessing
+warp induces a density wake in the collisionless dark matter, which acts back
+on the original warp, transferring energy and angular momentum between the warp
+and halo (dynamical friction). In most cases dynamical friction damps the warp,
+but in unusual circumstances (such as a halo that rotates in the same direction
+as the precession of the warp, or a warp in the equatorial plane of an
+axisymmetric prolate halo) friction can excite a warp. The damping/excitation
+time is usually short compared to the Hubble time for realistic systems. Thus
+most warps cannot be primordial; they must be maintained by some ongoing
+excitation mechanism.",9408068v1
+1995-09-14,Another Look at Gaussian Isocurvature Hot Dark Matter Models For Large- Scale Structure,"We examine Gaussian isocurvature hot dark matter (massive neutrino) models
+for large-scale structure in which the initial density perturbations are
+produced in the baryons with a power--law spectrum $P_B(k) = Ak^{n_B}$. We
+calculate the linearly-evolved power spectrum and cosmic microwave
+fluctuations. We find that models with only isocurvature perturbations are
+inconsistent with observations of damped Ly$\alpha$ systems and COBE
+constraints on the power index. However, models which contain a mixture of
+adiabatic and isocurvature perturbations can be made consistent with COBE,
+galaxy surveys and damped Ly$\alpha$ systems.Isocurvature hot dark matter
+models also produce a bias between baryons and neutrinos even in the linear
+regime. We find that this ``natural bias'' can increase the baryon fraction in
+small scale objects like damped Ly$\alpha$ systems, but it has no effect on
+cluster scales.",9509075v1
+1995-10-16,Star Formation and Chemical Evolution in Damped Lya Clouds,"Using the redshift evolution of the neutral hydrogen density, as inferred
+from observations of damped Ly$\alpha$ clouds, we calculate the evolution of
+star formation rates and elemental abundances in the universe. For most
+observables our calculations are in rough agreement with previous results based
+on the instantaneous re-cycling approximation (IRA). However, for the key
+metallicity tracer Zn, we find a better match to the observed abundance at high
+redshift than that given by the constant-yield IRA model. We investigate
+whether the redshift evolution of deuterium, depressions in the diffuse
+extragalactic gamma-ray background, and measurement of the MeV neutrino
+background may help determine if observational bias due to dust obscuration is
+important. We also indicate how the importance of dust on the calculations can
+be significantly reduced if correlations of the HI column density with
+metallicity are present. The possibilities for measuring $q_o$ with
+observations of elemental abundances in damped Ly$\alpha$ systems are
+discussed.",9510078v1
+1995-12-12,A radio Search for high redshift HI absorption,"Ground based optical observations have yielded considerable information on
+the statistics of damped-lyman alpha systems. In particular these systems are
+known to be the dominant repository of the observed neutral gas at high
+redshift. However, particularly at high redshift, there is the possibility that
+optical observations could be biased due to the exclusion of damped-lyman alpha
+systems that contain moderate to significant amounts of dust. Independent
+observational constraints on the neutral hydrogen content at high redshifts and
+the amount of dust in high redshift systems can be obtained from a radio search
+against the bright lobes of distant radio galaxies (which is less affected by
+the presence of dust in foreground damped-lyman alpha systems). We describe
+here a pilot radio survey along the line of sight to a small sample of high
+redshift radio galaxies, and also present some preliminary results. The survey
+uses a novel observing mode at the WSRT which enables one to make sensitive
+searches of a large redshift interval in a modest amount of telescope time.",9512069v1
+1996-01-26,The chemical evolution of galaxies at high redshift,"Observations of absorption lines in the spectra of distant QSOs offer a new
+approach for tracking the evolution of normal galaxies from early epochs to the
+present day. The damped Ly alpha systems are particularly suitable for
+measuring the properties of what are likely to be the progenitors of
+present-day luminous galaxies. We have recently concluded a long-term survey of
+30 damped absorbers (including eight from the literature) aimed at measuring
+the metallicity and dust content of the universe from redshift z = 3.39 to
+0.69. The major conclusions are that the epoch of chemical enrichment in
+galaxies may have begun at z = 2.5-3--corresponding to a look-back time of 14
+Gyr--and that at z = 2 the typical metallicity was 1/15 of solar. There is
+clear evidence for the presence of interstellar dust at z = 2, although several
+high-redshift galaxies, particularly the most metal-poor, appear to be
+essentially dust-free. We discuss the nature of the damped Ly alpha galaxies in
+the light of these and other new results.",9601153v1
+1996-07-23,A damped Ly-alpha candidate at z~0.1 toward Q 0439-433,"We report on the detection of a z_gal=0.101 galaxy projected on the sky at
+4.2 arcsec (or 5.2 h^{-1} kpc for q_o=0.5) from the quasar Q 0439-433
+(z_em=0.594). The HST spectrum of the quasar shows strong MgII, FeII, SiII,
+AlII and CIV absorption lines at the same redshift as the galaxy. The
+equivalent width ratios of the low ionization lines indicate that this system
+is probably damped with a neutral hydrogen column density of
+N_HI~10^{20}cm^{-2}. The CIV doublet presents a complex structure, and in
+particular a satellite with a velocity v=1100km/s relative to the galaxy.
+Additional HST and redshifted 21cm observations of this QSO-galaxy pair would
+offer an ideal opportunity to study the morphology of a damped absorber and the
+kinematics of the halo of a low-redshift galaxy.",9607111v2
+1997-08-11,Dynamos with different formulations of a dynamic alpha-effect,"We investigate the behaviour of $\alpha\Omega$ dynamos with a dynamic
+$\alpha$, whose evolution is governed by the imbalance between a driving and a
+damping term. We focus on truncated versions of such dynamo models which are
+often studied in connection with solar and stellar variability. Given the
+approximate nature of such models, it is important to study how robust they are
+with respect to reasonable changes in the formulation of the driving and
+damping terms. For each case, we also study the effects of changes of the
+dynamo number and its sign, the truncation order and initial conditions. Our
+results show that changes in the formulation of the driving term have important
+consequences for the dynamical behaviour of such systems, with the detailed
+nature of these effects depending crucially on the form of the driving term
+assumed, the value and the sign of the dynamo number and the initial
+conditions. On the other hand, the change in the damping term considered here
+seems to produce little qualitative effect.",9708093v1
+1997-11-20,ORT observations of the damped Lyman alpha system towards PKS 0201+113,"We report a deep radio search with the Ooty Radio Telescope (ORT) for the
+redshifted 21 cm absorption line from the damped Lyman alpha system seen at
+redshift 3.388 against the quasar PKS 0201+113. This is currently the most
+distant system for which a detection of 21 cm absorption has been claimed. The
+present observations have a sensitivity comparable to the earlier ones and
+detect no statistically significant absorption. We use the non-detection to
+place an upper limit of ~ 0.011 on the optical depth of the damped Lyman alpha
+absorber. This corresponds to a lower limit of ~ 5600 K to the spin temperature
+of the system. This is considerably higher than the previous upper limit of ~
+1380 K.",9711234v1
+1998-01-28,Dynamical Tide in Solar-Type Binaries,"Circularization of late-type main-sequence binaries is usually attributed to
+turbulent convection, while that of early-type binaries is explained by
+resonant excitation of g modes. We show that the latter mechanism operates in
+solar-type stars also and is at least as effective as convection, despite
+inefficient damping of g modes in the radiative core. The maximum period at
+which this mechanism can circularize a binary composed of solar-type stars in
+10 Gyr is as low as 3 days, if the modes are damped by radiative diffusion only
+and g-mode resonances are fixed; or as high as 6 days, if one allows for
+evolution of the resonances and for nonlinear damping near inner turning
+points. Even the larger theoretical period falls short of the observed
+transition period by a factor two.",9801289v1
+1998-02-06,Acoustic oscillations and viscosity,"Using a simple thermo-hydrodynamic model that respects relativistic
+causality, we revisit the analysis of qualitative features of acoustic
+oscillations in the photon-baryon fluid. The growing photon mean free path
+introduces transient effects that can be modelled by the causal generalization
+of relativistic Navier-Stokes-Fourier theory. Causal thermodynamics provides a
+more satisfactory hydrodynamic approximation to kinetic theory than the
+quasi-stationary (and non-causal) approximations arising from standard
+thermodynamics or from expanding the photon distribution to first order in the
+Thomson scattering time. The causal approach introduces small corrections to
+the dispersion relation obtained in quasi-stationary treatments. A dissipative
+contribution to the speed of sound slightly increases the frequency of the
+oscillations. The diffusion damping scale is slightly increased by the causal
+corrections. Thus quasi-stationary approximations tend to over-estimate the
+spacing and under-estimate the damping of acoustic peaks. In our simple model,
+the fractional corrections at decoupling are $\gtrsim 10^{-3}$.",9802074v2
+2000-02-29,Metallicity Evolution in the Early Universe,"Observations of the damped Lya systems provide direct measurements on the
+chemical enrichment history of neutral gas in the early universe. In this
+Letter, we present new measurements for four damped Lya systems at high
+redshift. Combining these data with [Fe/H] values culled from the literature,
+we investigate the metallicity evolution of the universe from z~1.5-4.5.
+Contrary to our expectations and the predictions of essentially every chemical
+evolution model, the N(HI)-weighted mean [Fe/H] metallicity exhibits minimal
+evolution over this epoch. For the individual systems, we report tentative
+evidence for an evolution in the unweighted [Fe/H] mean and the scatter in
+[Fe/H] with the higher redshift systems showing lower scatter and lower typical
+[Fe/H] values. We also note that no damped Lya system has [Fe/H] < -2.7 dex.
+Finally, we discuss the potential impact of small number statistics and dust on
+our conclusions and consider the implications of these results on chemical
+evolution in the early universe.",0002513v3
+2000-06-02,Surveys for z > 3 Damped Lyman-alpha Absorption Systems,"We have completed spectroscopic observations using LRIS on the Keck 1
+telescope of 30 very high redshift quasars, 11 selected for the presence of
+damped Ly-alpha absorption systems and 19 with redshifts z > 3.5 not previously
+surveyed for absorption systems. We have surveyed an additional 10 QSOs with
+the Lick 120'' and the Anglo-Australian Telescope. We have combined these with
+previous data resulting in a statistical sample of 646 QSOs and 85 damped
+Ly-alpha absorbers with column densities N(HI) >= 2 x 10^20 atoms/cm^2 covering
+the redshift range 0.008 <= z <= 4.694. To make the data in our statistical
+sample more readily available for comparison with scenarios from various
+cosmological models, we provide tables that includes all 646 QSOs from our new
+survey and previously published surveys. They list the minimum and maximum
+redshift defining the redshift path along each line of sight, the QSO emission
+redshift, and when an absorber is detected, the absorption redshift and
+measured HI column density. [see the paper for the complete abstract]",0006044v1
+2000-06-21,Constraints on the physical properties of the damped Ly-alpha system of Q0000-2619 at z = 3.054,"We present the detection of CII and CII* absorption in the z = 3.0543 damped
+Ly-alpha system toward Q0000-2619. The derived population ratio implies a fine
+structure excitation temperature between 19.6 and 21.6 K. The upper value sets
+a strict upper limit on the CMB temperature at this redshift, which is
+consistent with the predicted value of 11.05 K from standard cosmology. Under
+the assumptions of an ionization degree ranging from 0 to 10%, a gas kinetic
+temperature between 100 and 10000 K and a UV field with a Milky Way spectrum,
+the density of the absorber is constrained to be between 0.7 and 40 cm^-3 and
+the H-ionizing flux between 1 and 80 times the intensity of the Galactic UV
+field. If the damped Ly-alpha system is assumed to be homogeneous, the
+implication is that its size in the direction of the line of sight must be
+between 1 and 100 pc.",0006308v1
+2001-04-10,Damping scales of neutralino cold dark matter,"The lightest supersymmetric particle, most likely the neutralino, might
+account for a large fraction of dark matter in the Universe. We show that the
+primordial spectrum of density fluctuations in neutralino cold dark matter
+(CDM) has a sharp cut-off due to two damping mechanisms: collisional damping
+during the kinetic decoupling of the neutralinos at about 30 MeV (for typical
+neutralino and sfermion masses) and free streaming after last scattering of
+neutralinos. The last scattering temperature is lower than the kinetic
+decoupling temperature by one order of magnitude. The cut-off in the primordial
+spectrum defines a minimal mass for CDM objects in hierarchical structure
+formation. For typical neutralino and sfermion masses the first gravitationally
+bound neutralino clouds have to have masses above 10^(-7) solar masses.",0104173v2
+2002-05-15,Building the bridge between Damped Ly-alpha Absorbers and Lyman Break galaxies,"In 2000, we started the program ``Building the Bridge between Damped Ly-alpha
+Absorbers and Lyman-Break Galaxies: Ly-alpha Selection of Galaxies'' at the
+European Southern Observatory's Very Large Telescope. This project is an
+attempt to use Ly-alpha selection of high-z galaxies to bridge the gap between
+absorption- and emission-selected galaxies by creating a large database of z=3
+galaxies belonging to the abundant population of faint (R>25.5) galaxies probed
+by the Damped Ly-alpha Absorbers (DLAs). Here we present the first results of
+our program, namely the results from a deep Ly-alpha study of the field of the
+z=2.85 DLA towards Q2138-4427.",0205234v2
+2002-05-23,Constraining the strength of Dark Matter Interactions from Structure Formation,"We discuss the damping of primordial dark matter fluctuations, taking into
+account explicitly the interactions of dark matter - whatever their intensity -
+both with itself and with other particle species. Relying on a general
+classification of dark matter particle candidates, our analysis provides, from
+structure formation, a new set of constraints on the dark matter particle mass
+and interaction rates (in particular with photons and neutrinos).
+  This determines up to which cross sections the dark matter interactions may
+effectively be disregarded, and when they start playing an essential role,
+either through collisional damping or through an enhancement of the
+free-streaming scale. It leads us to extend the notions of Cold, Warm and Hot
+Dark Matter scenarios when dark matter interactions are no longer taken to be
+negligible. It also suggests the possibility of new scenarios of Collisional
+Warm Dark Matter, with moderate damping induced by dark matter interactions.",0205406v1
+2002-06-06,A catalogue of damped Lyman alpha absorption systems and radio flux densities of the background quasars,"We present a catalogue of the 322 damped Lyman alpha absorbers taken from the
+literature. All damped Lyman alpha absorbers are included, with no selection on
+redshift or quasar magnitude. Of these, 123 are candidates and await
+confirmation using high resolution spectroscopy. For all 322 objects we
+catalogue the radio properties of the background quasars, where known. Around
+60 quasars have radio flux densities above 0.1 Jy and approximately half of
+these have optical magnitudes brighter than V = 18. This compilation should
+prove useful in several areas of extragalactic/cosmological research.",0206091v1
+2002-11-14,Formation of small-scale structure in SUSY CDM,"The lightest supersymmetric particle, most likely the lightest neutralino, is
+one of the most prominent particle candidates for cold dark matter (CDM). We
+show that the primordial spectrum of density fluctuations in neutralino CDM has
+a sharp cut-off, induced by two different damping mechanisms. During the
+kinetic decoupling of neutralinos, non-equilibrium processes constitute
+viscosity effects, which damp or even absorb density perturbations in CDM.
+After the last scattering of neutralinos, free streaming induces neutralino
+flows from overdense to underdense regions of space. Both damping mechanisms
+together define a minimal mass scale for perturbations in neutralino CDM,
+before the inhomogeneities enter the nonlinear epoch of structure formation. We
+find that the very first gravitationally bound neutralino clouds ought to have
+masses above 10^{-6} solar masses, which is six orders of magnitude above the
+mass of possible axion miniclusters.",0211325v1
+2002-12-09,Galaxies at z=3 around Damped Ly-alpha Clouds,"We are exploring the connection between damped Ly-alpha absorbers (DLAs) and
+Lyman break galaxies (LBGs) using deep -- (5sigma)=26 m_{AB}-- broad band
+imaging (UBVI) of four wide fields (0.25 sq. deg. each) obtained at the Kitt
+Peak 4-m telescope with MOSAIC. Each field contains a damped system at z=3.
+  We want to address the nature of DLAs at high-redshifts: (1) Are they
+embedded in much larger systems of galaxies? (2) How does the spatial
+distribution of LBGs in 3D (space and redshift) correlate with the absorber?
+Contrary to most previous DLA studies, we are not looking for the absorber, and
+we do not rely on control fields because each of our fields is 40 Mpc
+(co-moving) on a side. We present preliminary results in two of our fields. In
+one case, we see an indication of an overdensity of galaxies on a scale of 5
+Mpc. We discuss the possible implications and sources of contamination of our
+results.",0212206v1
+2003-04-16,Building Blocks in Hierarchical Clustering Scenarios and their Connection with Damped Ly$α$ Systems,"We carried out a comprehensive analysis of the chemical properties of the
+interstellar medium (ISM) and the stellar population (SP) of current normal
+galaxies and their progenitors in a hierarchical clustering scenario. We
+compared the results with observations of Damped Lyman-$\alpha$ systems (DLAs)
+under the hypothesis that, at least, part of the observed DLAs could originate
+in the building blocks of today normal galaxies. We used a hydrodynamical
+cosmological code which includes star formation and chemical enrichment.
+Galaxy-like objects are identified at $z=0$ and then followed back in time.
+Random line-of-sights (LOS) are drawn through these structures in order to
+mimic Damped Lyman $\alpha$ systems. We then analysed the chemical properties
+of the ISM and SP along the LOS. We found that the progenitors of current
+galaxies in the field with mean $L <0.5 L^* $ and virial circular velocity of
+$100-250 {\rm km/sec}$ could be the associated DLA galaxies. For these systems
+we detected a trend for $<L/L^*>$ to increase with redshift.(Abridged)",0304303v2
+2003-05-16,The ESI/KeckII Damped Lya Abundance Database,"This paper presents chemical abundance measurements for 37 damped Lya systems
+at z>2.5 observed with the Echellette Spectrograph and Imager on the KeckII
+telescope. We measure the HI column densities of these damped systems through
+Voigt profile fits to their Lya profiles and we implement the apparent optical
+depth method to determine ionic column densities. Figures and tables of all
+relevant data are presented. A full analysis of the chemical enrichment history
+described by these observations will be presented in a future paper. This
+dataset is also valuable for efficiently planning future echelle observations
+and for rough abundance pattern analyses. We aim to make this entire data set
+public within three years of this publication.",0305312v1
+2003-10-28,Chemical Abundances in the Damped Lya Systems,"I introduce and review the data and analysis techniques used to measure
+abundances in the damped Lya systems, quasar absorption-line systems associated
+with galaxies in the early Universe. The observations and issues associated
+with their abundance analysis are very similar to those of the Milky Way's
+interstellar medium. We measure gas-phase abundances and are therefore subject
+to the effects of differential depletion. I review the impact of dust depletion
+and then present a summary of current results on the age-metallicity relation
+derived from damped Lya systems and new results impacting theories of
+nucleosynthesis in the early Universe.",0310814v1
+2004-12-14,Radiative Effects on Particle Acceleration in Electromagnetic Dominated Outflows,"Plasma outflows from gamma-ray bursts (GRB), pulsar winds, relativistic jets,
+and ultra-intense laser targets radiate high energy photons. However, radiation
+damping is ignored in conventional PIC simulations. In this letter, we study
+the radiation damping effect on particle acceleration via Poynting fluxes in
+two-and-half-dimensional particle-in-cell (PIC) plasma simulation of
+electron-positron plasmas. Radiation damping force is self-consistently
+calculated for each particle and reduces the net acceleration force. The
+emitted radiation is peaked within a few degrees from the direction of Poynting
+flux and strongly linear-polarized.",0412310v3
+2005-09-16,Damped Lyman alpha Systems,"Observations of damped Lyman alpha systems offer a unique window on the
+neutral-gas reservoirs that gave rise to galaxies at high redshifts. This
+review focuses on critical properties such as the H I and metal content of the
+gas and on independent evidence for star formation. Together, these provide an
+emerging picture of gravitationally bound objects in which accretion of gas
+from the IGM replenishes gas consumed by star formation. Other properties such
+as dust content, molecular content, ionized-gas content, gas kinematics, and
+galaxy identifications are also reviewed. These properties point to a
+multiphase ISM in which radiative and hydrodynamic feedback processes are
+present. Numerical simulations and other types of models used to describe
+damped Lyman alpha systems within the context of galaxy formation are also
+discussed.",0509481v2
+2005-11-11,Oscillation mode lifetimes in ksi Hydrae: Will strong mode damping limit asteroseismology of red giant stars?,"We introduce a new method to measure frequency separations and mode lifetimes
+of stochastically excited and damped oscillations, so-called solar-like
+oscillations. Our method shows that velocity data of the red giant star ksi Hya
+(Frandsen et al. 2002) support a large frequency separation between modes of
+roughly 7 microHz. We also conclude that the data are consistent with a mode
+lifetime of 2 days, which is so short relative to its pulsation period that
+none of the observed frequencies are unambiguous. Hence, we argue that the
+maximum asteroseismic output that can be obtained from these data is an average
+large frequency separation, the oscillation amplitude and the average mode
+lifetime. However, the significant discrepancy between the theoretical
+calculations of the mode lifetime (Houdek & Gough 2002) and our result based on
+the observations of ksi Hya, implies that red giant stars can help us better
+understand the damping and driving mechanisms of solar-like p-modes by
+convection.",0511344v1
+1996-12-14,Nonlinear Landau damping in collisionless plasma and inviscid fluid,"The evolution of an initial perturbation in Vlasov plasma is studied in the
+intrinsically nonlinear long-time limit dominated by the effects of particle
+trapping. After the possible transient linear exponential Landau damping, the
+evolution enters into a universal regime with an algebraically damped electric
+field, $E\propto1/t$. The trick used for the Vlasov equation is also applied to
+the two-dimensional (2D) Euler equation. It is shown that the stream function
+perturbation to a stable shear flow decays as $t^{-5/2}$ in the long-time
+limit. These results imply a strong non-ergodicity of the fluid element motion,
+which invalidates Gibbs-ensemble-based statistical theories of Vlasov and 2D
+fluid turbulence.",9612021v1
+1998-03-05,On how a joint interaction of two innocent partners (smooth advection & linear damping) produces a strong intermittency,"Forced advection of passive scalar by a smooth $d$-dimensional incompressible
+velocity in the presence of a linear damping is studied. Acting separately
+advection and dumping do not lead to an essential intermittency of the steady
+scalar statistics, while being mixed together produce a very strong
+non-Gaussianity in the convective range: $q$-th (positive) moment of the
+absolute value of scalar difference, $<|\theta (t;{\bf r})-\theta (t;0)|^{q}> $
+is proportional to $r^{\xi_{q}}$, $\xi _{q}=\sqrt{d^{2}/4+\alpha dq/[
+(d-1)D]}-d/2$, where $\alpha /D$ measures the rate of the damping in the units
+of the stretching rate. Probability density function (PDF) of the scalar
+difference is also found.",9803007v1
+1999-02-05,Nonlinear Dynamics of A Damped Magnetic Oscillator,"We consider a damped magnetic oscillator, consisting of a permanent magnet in
+a periodically oscillating magnetic field. A detailed investigation of the
+dynamics of this dissipative magnetic system is made by varying the field
+amplitude $A$. As $A$ is increased, the damped magnetic oscillator, albeit
+simple looking, exhibits rich dynamical behaviors such as symmetry-breaking
+pitchfork bifurcations, period-doubling transitions to chaos,
+symmetry-restoring attractor-merging crises, and saddle-node bifurcations
+giving rise to new periodic attractors. Besides these familiar behaviors, a
+cascade of ``resurrections'' (i.e., an infinite sequence of alternating
+restabilizations and destabilizations) of the stationary points also occurs. It
+is found that the stationary points restabilize (destabilize) through
+alternating subcritical (supercritical) period-doubling and pitchfork
+bifurcations. We also discuss the critical behaviors in the period-doubling
+cascades.",9902005v1
+1996-09-03,Mode damping in a commensurate monolayer solid,"The normal modes of a commensurate monolayer solid may be damped by mixing
+with elastic waves of the substrate. This was shown by B. Hall et al., Phys.
+Rev. B 32, 4932 (1985), for perpendicular adsorbate vibrations in the presence
+of an isotropic elastic medium. That work is generalized with an elastic
+continuum theory of the response of modes of either parallel or perpendicular
+polarization for a spherical adsorbate on a hexagonal substrate. The results
+are applied to the discussion of computer simulations and inelastic atomic
+scattering experiments for adsorbates on graphite. The extreme anisotropy of
+the elastic behavior of the graphite leads to quite different wave vector
+dependence of the damping for modes polarized perpendicular and parallel to the
+substrate. A phenomenological extension of the elasticity theory of the
+graphite to include bond-bending energies improves the description of substrate
+modes with strong anomalous dispersion and enables a semi-quantitative account
+of observed avoided crossings of the adlayer perpendicular vibration mode and
+the substrate Rayleigh mode.",9609032v1
+1997-12-08,Collective oscillations in superconductors revisited,"In the recent paper Ohashi and Takada (OT) made statements that in the clean
+limit considered by us (AV) in 1975, weakly damped collective oscillations in
+superconductors do not exist due to the Landau damping and their spectrum
+differs from that obtained in AV. In this Comment we would like to note that
+these statements arise as a result of a misunderstanding of the term ""clean""
+case. OT considered the limit of frequencies larger, than elastic scattering
+rate, meanwhile AV obtained weakly damped mode in the case when temperature is
+larger than scattering rate, the frequencies being smaller (!) than elastic
+scattering rate. All these problems were discussed in our review article in
+1979 which was, presumably, unknown to OT.",9712086v1
+1999-01-11,Vortex motion in superconducting YBCO inferred from the damping of the oscillations of a levitating magnetic microsphere,"The damping of the oscillations of a small permanent magnet (spherical shape,
+radius 0.1 mm) levitating between two parallel YBCO surfaces is measured as a
+function of oscillation amplitude and temperature. The losses in the samples
+(epitaxial thin films, bulk granular and bulk melt-textured) are analyzed in
+terms of oscillating shielding currents flowing through trapped flux lines
+whose motion gives rise to electric fields. We find dissipation to originate
+from different mechanisms of flux dynamics. At small amplitudes there is a
+linear regime described by a surface resistance varying from 10^-9 Ohm for bulk
+samples down to 10^-13 Ohm for the thin films at low temperatures. With
+increasing amplitude various nonlinear regimes are observed, firstly collective
+pinning with diverging energy barriers, secondly in bulk samples above 85 K
+hysteretic damping, and finally in thin films exponentially large losses which
+can be described by pinning energies vanishing linearly at large currents.",9901085v1
+1999-10-07,On the relative positions of the $2Δ$ peaks in Raman and tunneling spectra of d-wave superconductors,"We study $B_{1g}$ Raman intensity $R(\Omega)$ and the density of states
+$N(\omega)$ in isotropic 2D d-wave superconductors. For an ideal gas,
+$R(\Omega)$ and $N(\omega)$ have sharp peaks at $\Omega =2\Delta$ and $\omega
+=\Delta$, respectively, where $\Delta$ is the maximum value of the gap.
+  We study how the peak positions are affected by the fermionic damping due to
+impurity scattering.
+  We show that while the damping generally shifts the peak positions to larger
+frequencies, the peak in $R(\Omega)$ still occurs at almost twice the peak
+position in $N(\omega)$ and therefore cannot account for the experimentally
+observed downturn shift of the peak frequency in $R(\Omega)$ in underdoped
+cuprates compared to twice that in $N(\omega)$. We also discuss how the
+fermionic damping affects the dynamical spin susceptibility.",9910090v1
+2000-03-31,Kinetic Theory of Collective Excitations and Damping in Bose-Einstein Condensed Gases,"We calculate the frequencies and damping rates of the low-lying collective
+modes of a Bose-Einstein condensed gas at nonzero temperature. We use a complex
+nonlinear Schr\""odinger equation to determine the dynamics of the condensate
+atoms, and couple it to a Boltzmann equation for the noncondensate atoms. In
+this manner we take into account both collisions between
+noncondensate-noncondensate and condensate-noncondensate atoms. We solve the
+linear response of these equations, using a time-dependent gaussian trial
+function for the condensate wave function and a truncated power expansion for
+the deviation function of the thermal cloud. As a result, our calculation turns
+out to be characterized by two dimensionless parameters proportional to the
+noncondensate-noncondensate and condensate-noncondensate mean collision times.
+We find in general quite good agreement with experiment, both for the
+frequencies and damping of the collective modes.",0003517v1
+2000-09-01,The broad Brillouin doublets and central peak of KTaO_3,"The incipient ferroelectric KTaO3 presents low-T Brillouin spectra
+anomalies,e.g. a broad central peak (CP), and some additional Brillouin
+doublets (BD), whose origin is interpreted in terms of phonon-density
+fluctuation processes. A parameterisation from new extensive high-resolution
+neutron-scattering measurements is used to show that hydrodynamic second sound
+from high damping (compared to BD frequency) TA phonons may exist in the
+crystal. Furthermore, low damping thermal phonons may scatter light through
+two-phonon difference processes and appear on the Brillouin spectra either as a
+sharp or a broader BD, depending on the phonon damping and group velocity . The
+comparison between computed anisotropies and experimental measurements favours
+the second process.",0009012v1
+2001-01-15,Temperature Dependence of Damping and Frequency Shifts of the Scissors Mode of a trapped Bose-Einstein Condensate,"We have studied the properties of the scissors mode of a trapped
+Bose-Einstein condensate of $^{87}$Rb atoms at finite temperature. We measured
+a significant shift in the frequency of the mode below the hydrodynamic limit
+and a strong dependence of the damping rate as the temperature increased. We
+compared our damping rate results to recent theoretical calculations for other
+observed collective modes finding a fair agreement. From the frequency
+measurements we deduce the moment of inertia of the gas and show that it is
+quenched below the transition point, because of the superfluid nature of the
+condensed gas.",0101213v2
+2001-03-16,Gap Anisotropy and de Haas-van Alphen Effect in Type-II Superconductors,"We present a theoretical study on the de Haas-van Alphen (dHvA) oscillation
+in the vortex state of type-II superconductors, with a special focus on the
+connection between the gap anisotropy and the oscillation damping. Numerical
+calculations for three different gap structures clearly indicate that the
+average gap along extremal orbits is relevant for the magnitude of the extra
+damping, thereby providing a support for experimental efforts to probe gap
+anisotropy through the dHvA signal. We also derive an analytic formula for the
+extra damping which gives a good fit to the numerical results.",0103336v3
+2001-04-10,Quantum phase transitions and collective modes in d-wave superconductors,"Fluctuations near second-order quantum phase transitions in d-wave
+superconductors can cause strong damping of fermionic excitations, as observed
+in photoemission experiments. The damping of the gapless nodal quasiparticles
+can arise naturally in the quantum-critical region of a transition with an
+additional spin-singlet, zero momentum order parameter; we argue that the
+transition to a d_x^2-y^2 + i d_xy pairing state is the most likely possibility
+in this category. On the other hand, the gapped antinodal quasiparticles can be
+strongly damped by the coupling to antiferromagnetic spin fluctuations arising
+from the proximity to a Neel-ordered state. We review some aspects of the
+low-energy field theories for both transitions and the corresponding
+quantum-critical behavior. In addition, we discuss the spectral properties of
+the collective modes associated with the proximity to a superconductor with
+d_x^2-y^2 + i d_xy symmetry, and implications for experiments.",0104176v1
+2002-04-11,Nonequilibrium relaxation in neutral BCS superconductors: Ginzburg-Landau approach with Landau damping in real time,"We present a field-theoretical method to obtain consistently the equations of
+motion for small amplitude fluctuations of the order parameter directly in real
+time for a homogeneous, neutral BCS superconductor. This method allows to study
+the nonequilibrium relaxation of the order parameter as an initial value
+problem. We obtain the Ward identities and the effective actions for small
+phase the amplitude fluctuations to one-loop order. Focusing on the
+long-wavelength, low-frequency limit near the critical point, we obtain the
+time-dependent Ginzburg-Landau effective action to one-loop order, which is
+nonlocal as a consequence of Landau damping. The nonequilibrium relaxation of
+the phase and amplitude fluctuations is studied directly in real time. The
+long-wavelength phase fluctuation (Bogoliubov-Anderson-Goldstone mode) is
+overdamped by Landau damping and the relaxation time scale diverges at the
+critical point, revealing critical slowing down.",0204239v2
+2002-05-21,Linear spin waves in a trapped Bose gas,"An ultra-cold Bose gas of two-level atoms can be thought of as a spin-1/2
+Bose gas. It supports spin-wave collective modes due to the exchange mean
+field. Such collective spin oscillations have been observed in recent
+experiments at JILA with ${}^{87}$Rb atoms confined in a harmonic trap. We
+present a theory of the spin-wave collective modes based on the moment method
+for trapped gases. In the collisionless and hydrodynamic limits, we derive
+analytic expressions for the frequencies and damping rates of modes with dipole
+and quadrupole symmetry. We find that the frequency for a given mode is given
+by a temperature independent function of the peak density $n$, and falls off as
+$1/n$. We also find that, to a very good approximation, excitations in the
+radial and axial directions are decoupled. We compare our model to the
+numerical integration of a one dimensional version of the kinetic equation and
+find very good qualitative agreement. The damping rates, however, show the
+largest deviation for intermediate densities, where one expects Landau damping
+-- which is unaccounted for in our moment approach -- to play a significant
+role.",0205450v1
+2002-08-02,Landau damping of transverse quadrupole oscillations of an elongated Bose-Einstein condensate,"We study the interaction between low-lying transverse collective oscillations
+and thermal excitations of an elongated Bose-Einstein condensate by means of
+perturbation theory. We consider a cylindrically trapped condensate and
+calculate the transverse elementary excitations at zero temperature by solving
+the linearized Gross-Pitaevskii equations in two dimensions. We use them to
+calculate the matrix elements between thermal excited states coupled with the
+quasi-2D collective modes. The Landau damping of transverse collective modes is
+investigated as a function of temperature. At low temperatures, the damping
+rate due to the Landau decay mechanism is in agreement with the experimental
+data for the decay of the transverse quadrupole mode, but it is too small to
+explain the slow experimental decay of the transverse breathing mode. The
+reason for this discrepancy is discussed.",0208047v1
+2002-08-28,Transverse modes of a cigar-shaped Bose-Einstein condensate,"We discuss the collective modes in a harmonically trapped, highly-elongated
+Bose condensed gas. The transverse breathing mode exhibits a number of
+interesting features, such as the insensitivity of the condensate mode
+frequency to the interaction strength, and the closeness of the frequency to
+that of the non-condensed thermal cloud in the collisionless limit. Using
+finite temperature simulations, we show that these features are responsible for
+the very small damping rate observed experimentally. Our results for the
+temperature dependence of the damping rate and frequency shift are in excellent
+agreement with experiment. We also demonstrate that the unusually small damping
+rate does not arise for the $m=2$ mode or for more isotropic trap potentials,
+suggesting further possible experimental tests of our theory.",0208567v1
+2002-10-31,Stationary quantum statistics of a non-Markovian atom laser,"We present a steady state analysis of a quantum-mechanical model of an atom
+laser. A single-mode atomic trap coupled to a continuum of external modes is
+driven by a saturable pumping mechanism. In the dilute flux regime, where
+atom-atom interactions are negligible in the output, we have been able to solve
+this model without making the Born-Markov approximation. The more exact
+treatment has a different effective damping rate and occupation of the lasing
+mode, as well as a shifted frequency and linewidth of the output. We examine
+gravitational damping numerically, finding linewidths and frequency shifts for
+a range of pumping rates. We treat mean field damping analytically, finding a
+memory function for the Thomas-Fermi regime. The occupation and linewidth are
+found to have a nonlinear scaling behavior which has implications for the
+stability of atom lasers.",0210688v1
+2003-03-23,Damping of micromechanical structures by paramagnetic relaxation,"We find that the damping of micromechanical cantilevers is sensitive to the
+relaxation dynamics of paramagnetic ions contained within the levers. We
+measure cantilevers containing paramagnetic Mn ions as a function of
+temperature, magnetic field, and the vibrational mode of the lever and find
+that the levers damping is strongly enhanced by the interplay between the
+motion of the lever, the ions magnetic anisotropy, and the ratio of the ions
+longitudinal relaxation rate to the resonance frequency of the cantilever. This
+enhancement can improve the levers ability to probe the relaxation behavior of
+paramagnetic or superparamagetic systems; it may also represent a previously
+unrecognized source of intrinsic dissipation in micromechanical structures.",0303489v1
+2003-03-27,Oscillatory wave fronts in chains of coupled nonlinear oscillators,"Wave front pinning and propagation in damped chains of coupled oscillators
+are studied. There are two important thresholds for an applied constant stress
+$F$: for $|F|<F_{cd}$ (dynamic Peierls stress), wave fronts fail to propagate,
+for $F_{cd} < |F| < F_{cs}$ stable static and moving wave fronts coexist, and
+for $|F| > F_{cs}$ (static Peierls stress) there are only stable moving wave
+fronts. For piecewise linear models, extending an exact method of Atkinson and
+Cabrera's to chains with damped dynamics corroborates this description. For
+smooth nonlinearities, an approximate analytical description is found by means
+of the active point theory. Generically for small or zero damping, stable wave
+front profiles are non-monotone and become wavy (oscillatory) in one of their
+tails.",0303576v1
+2003-06-03,Local Relaxation and Collective Stochastic Dynamics,"Damping and thermal fluctuations have been introduced to collective normal
+modes of a magnetic system in recent modeling of dynamic thermal magnetization
+processes. The connection between this collective stochastic dynamics and
+physical local relaxation processes is investigated here. A system of two
+coupled magnetic grains embedded in two separate oscillating thermal baths is
+analyzed with no \QTR{it}{a priori} assumptions except that of a Markovian
+process. It is shown explicitly that by eliminating the oscillating thermal
+bath variables, collective stochastic dynamics occurs in the normal modes of
+the magnetic system. The grain interactions cause local relaxation to be felt
+by the collective system and the dynamic damping to reflect the system
+symmetry. This form of stochastic dynamics is in contrast to a common
+phenomenological approach where a thermal field is added independently to the
+dynamic equations of each discretized cell or interacting grain. The dependence
+of this collective stochastic dynamics on the coupling strength of the magnetic
+grains and the relative local damping is discussed.",0306047v1
+2003-07-22,Classical dynamics of a nano-mechanical resonator coupled to a single-electron transistor,"We analyze the dynamics of a nano-mechanical resonator coupled to a
+single-electron transistor (SET) in the regime where the resonator behaves
+classically. A master equation is derived describing the dynamics of the
+coupled system which is then used to obtain equations of motion for the average
+charge state of the SET and the average position of the resonator. We show that
+the action of the SET on the resonator is very similar to that of a thermal
+bath, as it leads to a steady-state probability-distribution for the resonator
+which can be described by mean values of the resonator position, a renormalized
+frequency, an effective temperature and an intrinsic damping constant.
+Including the effects of extrinsic damping and finite temperature, we find that
+there remain experimentally accessible regimes where the intrinsic damping of
+the resonator still dominates its behavior. We also obtain the average current
+through the SET as a function of the coupling to the resonator.",0307528v1
+2003-10-09,Direct measurement of molecular stiffness and damping in confined water layers,"We present {\em direct} and {\em linear} measurements of the normal stiffness
+and damping of a confined, few molecule thick water layer. The measurements
+were obtained by use of a small amplitude (0.36 $\textrm{\AA}$), off-resonance
+Atomic Force Microscopy (AFM) technique. We measured stiffness and damping
+oscillations revealing up to 7 layers separated by 2.56 $\pm$ 0.20
+$\textrm{\AA}$. Relaxation times could also be calculated and were found to
+indicate a significant slow-down of the dynamics of the system as the confining
+separation was reduced. We found that the dynamics of the system is determined
+not only by the interfacial pressure, but more significantly by solvation
+effects which depend on the exact separation of tip and surface. Thus `
+solidification\rq seems to not be merely a result of pressure and confinement,
+but depends strongly on how commensurate the confining cavity is with the
+molecule size. We were able to model the results by starting from the simple
+assumption that the relaxation time depends linearly on the film stiffness.",0310219v1
+2004-03-08,Mean-field magnetization relaxation in conducting ferromagnets,"Collective ferromagnetic motion in a conducting medium is damped by the
+transfer of the magnetic moment and energy to the itinerant carriers. We
+present a calculation of the corresponding magnetization relaxation as a
+linear-response problem for the carrier dynamics in the effective exchange
+field of the ferromagnet. In electron systems with little intrinsic spin-orbit
+interaction, a uniform magnetization motion can be formally eliminated by going
+into the rotating frame of reference for the spin dynamics. The ferromagnetic
+damping in this case grows linearly with the spin-flip rate when the latter is
+smaller than the exchange field and is inversely proportional to the spin-flip
+rate in the opposite limit. These two regimes are analogous to the
+""spin-pumping"" and the ""breathing Fermi-surface"" damping mechanisms,
+respectively. In diluted ferromagnetic semiconductors, the hole-mediated
+magnetization can be efficiently relaxed to the itinerant-carrier degrees of
+freedom due to the strong spin-orbit interaction in the valence bands.",0403224v2
+2004-04-05,Low-temperature specific heat of real crystals: Possibility of leading contribution of optical and short-wavelength acoustical vibrations,"We point out that the repeatedly reported glass-like properties of
+crystalline materials are not necessarily associated with localized (or
+quasilocalized) excitations. In real crystals, optical and short-wavelength
+acoustical vibrations remain damped due to defects down to zero temperature. If
+such a damping is frequency-independent, e.g. due to planar defects or charged
+defects, these optical and short-wavelength acoustical vibrations yield a
+linear-in-$T$ contribution to the low-temperature specific heat of the crystal
+lattices. At low enough temperatures such a contribution will prevail over that
+of the long-wavelength acoustical vibrations (Debye contribution). The
+crossover between the linear and the Debye regime takes place at $T^* \propto
+\sqrt N$, where $N$ is the concentration of the defects responsible for the
+damping. Estimates show that this crossover could be observable.",0404063v4
+2004-04-20,Decoherence processes during active manipulation of excitonic qubits in semiconductor quantum dots,"Using photoluminescence spectroscopy, we have investigated the nature of Rabi
+oscillation damping during active manipulation of excitonic qubits in
+self-assembled quantum dots. Rabi oscillations were recorded by varying the
+pulse amplitude for fixed pulse durations between 4 ps and 10 ps. Up to 5
+periods are visible, making it possible to quantify the excitation dependent
+damping. We find that this damping is more pronounced for shorter pulse widths
+and show that its origin is the non-resonant excitation of carriers in the
+wetting layer, most likely involving bound-to-continuum and continuum-to-bound
+transitions.",0404465v1
+2004-07-29,From subdiffusion to superdiffusion of particles on solid surfaces,"We present a numerical and partially analytical study of classical particles
+obeying a Langevin equation that describes diffusion on a surface modeled by a
+two dimensional potential. The potential may be either periodic or random.
+Depending on the potential and the damping, we observe superdiffusion,
+large-step diffusion, diffusion, and subdiffusion. Superdiffusive behavior is
+associated with low damping and is in most cases transient, albeit often long.
+Subdiffusive behavior is associated with highly damped particles in random
+potentials. In some cases subdiffusive behavior persists over our entire
+simulation and may be characterized as metastable. In any case, we stress that
+this rich variety of behaviors emerges naturally from an ordinary Langevin
+equation for a system described by ordinary canonical Maxwell-Boltzmann
+statistics.",0407781v1
+2004-08-18,Theory of Magnetic Polaron,"The concept of magnetic polaron is analysed and developed to elucidate the
+nature of itinerant charge carrier states in magnetic semiconductors and
+similar complex magnetic materials. By contrasting the scattering and bound
+states of carriers within the $s-d$ exchange model, the nature of bound states
+at finite temperatures is clarified. The free magnetic polaron at certain
+conditions is realized as a bound state of the carrier (electron or hole) with
+the spin wave. Quite generally, a self-consistent theory of a magnetic polaron
+is formulated within a nonperturbative many-body approach, the Irreducible
+Green Functions (IGF) method which is used to describe the quasiparticle
+many-body dynamics at finite temperatures. Within the above many-body approach
+we elaborate a self-consistent picture of dynamic behavior of two interacting
+subsystems, the localized spins and the itinerant charge carriers. In
+particular, we show that the relevant generalized mean fields emerges naturally
+within our formalism. At the same time, the correct separation of elastic
+scattering corrections permits one to consider the damping effects (inelastic
+scattering corrections) in the unified and coherent fashion. The damping of
+magnetic polaron state, which is quite different from the damping of the
+scattering states, finds a natural interpretation within the present
+self-consistent scheme.",0408404v2
+2004-09-27,Dephasing and delay time fluctuations in the chaotic scattering of a quantum particle weakly coupled to a complicated background,"Effect of a complicated many-body environment is analyzed on the chaotic
+motion of a quantum particle in a mesoscopic ballistic structure. The dephasing
+and absorption phenomena are treated on the same footing in the framework of a
+schematic microscopic model. The single-particle doorway resonance states
+excited in the structure via an external channel are damped not only because of
+the escape onto such channels but also due to ulterior population of the
+long-lived background states. The transmission through the structure is
+presented as an incoherent sum of the flow formed by the interfering damped
+doorway resonances and the retarded flow of the particles reemitted by the
+environment. The resulting internal damping as well as the dephasing rate are
+uniquely expressed in terms of the spreading width which controls the coupling
+to the background. The formation of the long-lived fine-structure resonances
+strongly enhances delay time fluctuations thus broadening the delay time
+distribution.",0409690v1
+2005-01-18,Damping effects and the metal-insulator transition in the two-dimensional electron gas,"The damping of single-particle degrees of freedom in strongly correlated
+two-dimensional Fermi systems is analyzed. Suppression of the scattering
+amplitude due to the damping effects is shown to play a key role in preserving
+the validity of the Landau-Migdal quasiparticle picture in a region of a phase
+transition, associated with the divergence of the quasiparticle effective mass.
+The results of the analysis are applied to elucidate the behavior of the
+conductivity $\sigma(T)$ of the two-dimensional dilute electron gas in the
+density region where it undergoes a metal-insulator transition.",0501427v2
+2005-04-17,Dynamics of thermoelastic thin plates: A comparison of four theories,"Four distinct theories describing the flexural motion of thermoelastic thin
+plates are compared. The theories are due to Chadwick, Lagnese and Lions,
+Simmonds, and Norris. Chadwick's theory requires a 3D spatial equation for the
+temperature but is considered the most accurate as the others are derivable
+from it by different approximations. Attention is given to the damping of
+flexural waves. Analytical and quantitative comparisons indicate that the
+Lagnese and Lions model with a 2D temperature equation captures the essential
+features of the thermoelastic damping, but contains systematic inaccuracies.
+These are attributable to the approximation for the first moment of the
+temperature used in deriving the Lagnese and Lions equation. Simmonds' model
+with an explicit formula for temperature in terms of plate deflection is the
+simplest of all but is accurate only at low frequency, where the damping is
+linearly proportional to the frequency. It is shown that the Norris model,
+which is almost as simple as Simmond's, is as accurate as the more precise but
+involved theory of Chadwick.",0504412v1
+2005-04-29,Probing temperature and damping rates in Bose-Einstein condensates using ultraslow light experiments,"We propose a method to probe Landau and Beliaev processes in dilute trapped
+atomic condensates with a multiple state structure using ultraslow light
+experimental configurations. Under certain conditions, damping rates from these
+collisional processes are directly proportional to the dephasing rates, making
+it possible to determine damping rates through measurement of the dephasing. In
+the ultraslow light systems we consider, Landau decay rates are enhanced at low
+momenta, which allows one to distinguish between Landau-dominated and
+Beliaev-dominated regimes at the same temperature. Furthermore, the enhancement
+of Landau rates potentially provides a way to measure low temperatures ($T \ll
+T_c$) in dilute condensates more accurately than current methods permit.",0504784v2
+2005-05-23,Anharmonic vs. relaxational sound damping in glasses: I. Brillouin scattering from densified silica,"This series discusses the origin of sound damping and dispersion in glasses.
+In particular, we address the relative importance of anharmonicity versus
+thermally activated relaxation. In this first article, Brillouin-scattering
+measurements of permanently densified silica glass are presented. It is found
+that in this case the results are compatible with a model in which damping and
+dispersion are only produced by the anharmonic coupling of the sound waves with
+thermally excited modes. The thermal relaxation time and the unrelaxed velocity
+are estimated.",0505558v3
+2005-05-23,Anharmonic vs. relaxational sound damping in glasses: II. Vitreous silica,"The temperature dependence of the frequency dispersion in the sound velocity
+and damping of vitreous silica is reanalyzed. Thermally activated relaxation
+accounts for the sound attenuation observed above 10 K at sonic and ultrasonic
+frequencies. Its extrapolation to the hypersonic regime reveals that the
+anharmonic coupling to the thermal bath becomes important in
+Brillouin-scattering measurements. At 35 GHz and room temperature, the damping
+due to this anharmonicity is found to be nearly twice that produced by
+thermally activated relaxation. The analysis also reveals a sizeable velocity
+increase with temperature which is not related with sound dispersion. This
+suggests that silica experiences a gradual structural change that already
+starts well below room temperature.",0505560v2
+2005-06-06,Heat Bath Approach to Landau Damping and Pomeranchuk Quantum Critical Points,"We study the problem of the damping of collective modes close to a
+Pomeranchuk quantum critical point in a Fermi liquid. In analogy with problems
+in dissipative open quantum systems, we derive the Landau damping of a Fermi
+liquid by integrating out a macroscopic number of degrees of freedom from a
+generating functional. Being a reformulation of the linearized Boltzmann
+equation this approach reproduces well-known results from the theory of Fermi
+liquids. We also study the Bethe-Salpeter equations within the Landau theory
+and discuss the implications of these results on quantum phase transitions of
+the Pomeranchuk type and its dynamical exponent, z. We apply our results to the
+electronic nematic instability and find z=3 in the collisionless limit.",0506146v3
+2005-07-01,Measurement of Dissipation of a Three-Level rf SQUID Qubit,"The dissipation-induced relaxation (T_1) time of a macroscopic quantum system
+- a \{lambda}-type three-level rf SQUID flux qubit weakly coupled to control
+and readout circuitry (CRC) - is investigated via time-domain measurement. The
+measured interwell relaxation time of the qubit's first excited state,
+T_1=3.45+/-0.06 \{mu}s, corresponds to an effective damping resistance of the
+flux qubit R=1.6+/-0.1 M\{omega} which is much lower than the intrinsic
+quasiparticle resistance of the Josephson tunnel junction. An analysis of the
+system shows that although the CRC is very weakly coupled to the qubit it is
+the primary source of damping. This type of damping can be significantly
+reduced by the use of more sophisticated circuit design to allow coherent
+manipulation of qubit states.",0507008v1
+2005-09-19,Interaction effects on magnetooscillations in a two-dimensional electron gas,"Motivated by recent experiments, we study the interaction corrections to the
+damping of magnetooscillations in a two-dimensional electron gas (2DEG). We
+identify leading contributions to the interaction-induced damping which are
+induced by corrections to the effective mass and quantum scattering time. The
+damping factor is calculated for Coulomb and short-range interaction in the
+whole range of temperatures, from the ballistic to the diffusive regime. It is
+shown that the dominant effect is that of the renormalization of the effective
+electron mass due to the interplay of the interaction and impurity scattering.
+The results are relevant to the analysis of experiments on magnetooscillations
+(in particular, for extracting the value of the effective mass) and are
+expected to be useful for understanding the physics of a high-mobility 2DEG
+near the apparent metal-insulator transition.",0509463v2
+2005-12-20,Damping of zero sound in Luttinger liquids,"We calculate the damping gamma_q of collective density oscillations (zero
+sound) in a one-dimensional Fermi gas with dimensionless forward scattering
+interaction F and quadratic energy dispersion k^2 / 2 m at zero temperature.
+For wave-vectors | q| /k_F small compared with F we find to leading order
+gamma_q = v_F^{-1} m^{-2} Y (F) | q |^3, where v_F is the Fermi velocity, k_F
+is the Fermi wave-vector, and Y (F) is proportional to F^3 for small F. We also
+show that zero-sound damping leads to a finite maximum proportional to |k - k_F
+|^{-2 + 2 eta} of the charge peak in the single-particle spectral function,
+where eta is the anomalous dimension. Our prediction agrees with photoemission
+data for the blue bronze K_{0.3}MoO_3.",0512494v4
+2006-04-11,Damping and dispersion of oscillating modes of a multicomponent ionic mixture in a magnetic field,"The collective-mode spectrum of a multicomponent magnetized ionic mixture for
+small wave number k is studied with the use of magnetohydrodynamics and formal
+kinetic theory. Apart from the usual thermal and diffusive modes, the spectrum
+contains a set of four oscillating modes. By evaluating the k^2 contributions
+to the eigenfrequencies, the damping and the dispersion of these oscillating
+modes are determined. The long-range nature of the Coulomb interactions is
+shown to imply that Burnett terms with higher-order gradients in the linear
+phenomenological laws have to be taken into account in order to obtain a full
+description of all damping and dispersion effects.",0604272v1
+2006-05-16,Collective mode damping and viscosity in a 1D unitary Fermi gas,"We calculate the damping of the Bogoliubov-Anderson mode in a one-dimensional
+two-component attractive Fermi gas for arbitrary coupling strength within a
+quantum hydrodynamic approach. Using the Bethe-Ansatz solution of the 1D
+BCS-BEC crossover problem, we derive analytic results for the viscosity
+covering the full range from a Luther-Emery liquid of weakly bound pairs to a
+Lieb-Liniger gas of strongly bound bosonic dimers. At the unitarity point, the
+system is a Tonks-Girardeau gas with a universal constant $\alpha_{\zeta}=0.38$
+in the viscosity $\zeta=\alpha_{\zeta}\hbar n$ for T=0. For the trapped case,
+we calculate the Q-factor of the breathing mode and show that the damping
+provides a sensitive measure of temperature in 1D Fermi gases.",0605413v2
+2006-07-06,Low energy theory of a single vortex and electronic quasiparticles in a d-wave superconductor,"We highlight the properties of a simple model (contained in our recent work)
+of the quantum dynamics of a single point vortex interacting with the nodal
+fermionic quasiparticles of a d-wave superconductor. We describe the
+renormalization of the vortex motion by the quasiparticles: at T=0, the
+quasiparticles renormalize the vortex mass and introduce only a weak sub-Ohmic
+damping. Ohmic (or `Bardeen-Stephen' damping) appears at T>0, with the damping
+co-efficient vanishing ~ T^2 with a universal prefactor. Conversely, quantum
+fluctuations of the vortex renormalize the quasiparticle spectrum. A point
+vortex oscillating in a harmonic pinning potential has no zero-bias peak in the
+electronic local density of states (LDOS), but has small satellite features at
+an energy determined by the pinning potential. These are proposed as the origin
+of sub-gap LDOS peaks observed in scanning tunneling microscopic studies of the
+LDOS near a vortex.",0607137v2
+2005-08-23,Investigations of Process Damping Forces in Metal Cutting,"Using finite element software developed for metal cutting by Third Wave
+Systems we investigate the forces involved in chatter, a self-sustained
+oscillation of the cutting tool. The phenomena is decomposed into a vibrating
+tool cutting a flat surface work piece, and motionless tool cutting a work
+piece with a wavy surface. While cutting the wavy surface, the shearplane was
+seen to oscillate in advance of the oscillation of the depth of cut, as were
+the cutting, thrust, and shear plane forces. The vibrating tool was used to
+investigate process damping through the interaction of the relief face of the
+tool and the workpiece. Crushing forces are isolated and compared to the
+contact length between the tool and workpiece. We found that the wavelength
+dependence of the forces depended on the relative size of the wavelength to the
+length of the relief face of the tool. The results indicate that the damping
+force from crushing will be proportional to the cutting speed for short tools,
+and inversely proportional for long tools.",0508102v1
+1999-09-27,R-Modes in Superfluid Neutron Stars,"The analogs of r-modes in superfluid neutron stars are studied here. These
+modes, which are governed primarily by the Coriolis force, are identical to
+their ordinary-fluid counterparts at the lowest order in the small
+angular-velocity expansion used here. The equations that determine the next
+order terms are derived and solved numerically for fairly realistic superfluid
+neutron-star models. The damping of these modes by superfluid ``mutual
+friction'' (which vanishes at the lowest order in this expansion) is found to
+have a characteristic time-scale of about 10^4 s for the m=2 r-mode in a
+``typical'' superfluid neutron-star model. This time-scale is far too long to
+allow mutual friction to suppress the recently discovered gravitational
+radiation driven instability in the r-modes. However, the strength of the
+mutual friction damping depends very sensitively on the details of the
+neutron-star core superfluid. A small fraction of the presently acceptable
+range of superfluid models have characteristic mutual friction damping times
+that are short enough (i.e. shorter than about 5 s) to suppress the
+gravitational radiation driven instability completely.",9909084v1
+2001-02-08,Cyclotron damping and Faraday rotation of gravitational waves,"We study the propagation of gravitational waves in a collisionless plasma
+with an external magnetic field parallel to the direction of propagation. Due
+to resonant interaction with the plasma particles the gravitational wave
+experiences cyclotron damping or growth, the latter case being possible if the
+distribution function for any of the particle species deviates from
+thermodynamical equilibrium. Furthermore, we examine how the damping and
+dispersion depends on temperature and on the ratio between the cyclotron- and
+gravitational wave frequency. The presence of the magnetic field leads to
+different dispersion relations for different polarizations, which in turn imply
+Faraday rotation of gravitational waves.",0102031v2
+2007-02-07,Relativistic r-modes and shear viscosity,"We derive the relativistic equations for stellar perturbations, including in
+a consistent way shear viscosity in the stress-energy tensor, and we
+numerically integrate our equations in the case of large viscosity. We consider
+the slow rotation approximation, and we neglect the coupling between polar and
+axial perturbations. In our approach, the frequency and damping time of the
+emitted gravitational radiation are directly obtained. We find that,
+approaching the inviscid limit from the finite viscosity case, the continuous
+spectrum is regularized. Constant density stars, polytropic stars, and stars
+with realistic equations of state are considered. In the case of constant
+density stars and polytropic stars, our results for the viscous damping times
+agree, within a factor two, with the usual estimates obtained by using the
+eigenfunctions of the inviscid limit. For realistic neutron stars, our
+numerical results give viscous damping times with the same dependence on mass
+and radius as previously estimated, but systematically larger of about 60%.",0702040v1
+2000-08-18,Fabrication Process of Rounded Damped Detuned Structure,"Following the successful design and fabrication of Damped Detuned Structures
+(DDS), the JLC/NLC linear collider project advanced to Rounded Damped Detuned
+Structures (RDDS) with curved cross section of the cavity shape for increased
+shunt impedance. Various advanced techniques for fabricating RDDS1 disks
+comparing to those for DDS were established to satisfy the dimension accuracy
+of +-1 micron over the entire surface made by ultra-precision turning. These
+disks were assembled with almost the same stacking and bonding jigs and
+processes as those of DDS3 assembly. In consequence, the assembly showed little
+disk-to-disk misalignment within 1 micron before and after the process. Though,
+it had 200 micron smooth bowing, which was subsequently corrected as DDS3, and
+flares at both ends.",0008034v1
+2000-08-18,Meeting Tight Frequency Requirement of Rounded Damped Detuned Structure,"Following successful design and fabrication of damped detuned structures, the
+R&D for the accelerating structures of the NLC/JLC linear collider project
+proceeded to studies of Rounded Damped Detuned Structure with curved cross
+section of the cavity shape for increased shunt impedance. The important
+features of the structure are the accurately tuned accelerating mode frequency
+and the distribution of the first dipole modes smooth and close to the design
+distribution. These requirements were met based on the high-accuracy diamond
+turning with its capability to realize the periphery tolerance of two microns.
+The lowest dipole mode frequencies scattered by 0.6 MHz RMS. The error in the
+accelerating mode frequency averaged over a structure was 0.1 MHz by applying a
+feed-forward method.",0008035v1
+1992-03-16,Comment on ``Damping of energetic gluons and quarks in high-temperature QCD'',"Burgess and Marini have recently pointed out that the leading contribution to
+the damping rate of energetic gluons and quarks in the QCD plasma, given by
+$\gamma=c g^2\ln(1/g)T$, can be obtained by simple arguments obviating the need
+of a fully resummed perturbation theory as developed by Braaten and Pisarski.
+Their calculation confirmed previous results of Braaten and Pisarski, but
+contradicted those proposed by Lebedev and Smilga. While agreeing with the
+general considerations made by Burgess and Marini, I correct their actual
+calculation of the damping rates, which is based on a wrong expression for the
+static limit of the resummed gluon propagator. The effect of this, however,
+turns out to be cancelled fortuitously by another mistake, so as to leave all
+of their conclusions unchanged. I also verify the gauge independence of the
+results, which in the corrected calculation arises in a less obvious manner.",9203211v1
+1995-02-16,The Infrared Sensitivity of Screening and Damping in a Quark-Gluon Plasma,"All the next-to-leading order contributions to the quasi-particle dispersion
+laws of a quark-gluon plasma which due to infrared singularities are sensitive
+to the magnetic-mass scale are calculated using Braaten-Pisarski resummation.
+These relative-order-$g\ln(g)$ corrections are shown here to generally
+contribute to the dynamical screening of gluonic fields with frequencies below
+the plasma frequency as well as to the damping of propagating gluonic and
+fermionic quasi-particles. In the limit of vanishing wave-vector the infrared
+singularities disappear, but in a way that raises the possibility for formally
+higher orders of the Braaten-Pisarski scheme to equally contribute at
+next-to-leading order when the wave-vector is of the order of or less than the
+magnetic-mass scale. This is argued to be a problem in particular for the
+fermionic damping rate.",9502324v1
+1997-10-30,Damping rate for transverse gluons with finite soft momentum in hot QCD,"We calculate the damping rate for transverse gluons with {\nineti finite}
+soft momentum to leading order in perturbative hot QCD. The internal momenta of
+the one-loop contributing diagrams are soft. This means we have to use
+effective vertices and propagators which incorporate the so-called hard thermal
+loops. We expand the damping rate in powers of the incoming momentum and argue
+that the series ought to converge within a finite radius of convergence. We
+contrast such a behavior with the one obtained from a previous calculation that
+produced a logarithmic behavior, a calculation based on letting the gluon
+momentum come from the hard limit down towards the interior of the soft region.
+This difference in behavior may point to interesting physics around some
+`critical' region.",9710549v2
+1998-07-21,An infrared singularity in the damping rate for longitudinal gluons in hot QCD,"We calculate $\gamma_l(0)$, the damping rate for longitudinal on-shell gluons
+with zero momentum in hot QCD using the hard-thermal-loop (htl) scheme. We find
+it to be divergent in the infrared, which means that in this scheme
+$\gamma_l(0)$ is different from $\gamma_t(0)$, the corresponding damping rate
+for transverse gluons which is known to be finite. This result suggests that
+the htl scheme is infrared sensitive and thus may need to be improved upon in
+this sector. We discuss this issue after we present our calculation.",9807439v2
+1998-09-25,Damping rates in the MSSM and electroweak baryogenesis,"We present an analysis of the thermalization rate of Higgsinos and winos
+based on the imaginary part of the two-point Green function in the {\it
+unbroken} phase of the MSSM. We use improved propagators including resummation
+of hard thermal loops and the thermalization rate is computed at the one-loop
+level in the high temperature approximation. We find that the damping is
+typically dominated by scattering with gauge bosons, resulting in a damping
+rate of about $\gamma_{\Ht}\simeq 0.025T$, $\gamma_{\Wt}\simeq 0.065T$. The
+contribution from scattering with scalars is relatively small. Implications for
+baryogenesis are also discussed.",9809529v1
+2006-10-27,The soft fermion dispersion relation at next-to-leading order in hot QED,"We study next-to-leading order contributions to the soft static fermion
+dispersion relation in hot QED. We derive an expression for the complete
+next-to-leading order contribution to the retarded fermion self-energy. The
+real and imaginary parts of this expression give the next-to-leading order
+contributions to the mass and damping rate of the fermionic quasi-particle.
+Many of the terms that are expected to contribute according to the traditional
+power counting argument are actually subleading. We explain why the power
+counting method over estimates the contribution from these terms. For the
+electron damping rate in QED we obtain: $\gamma_{QED} = \frac{e^2
+T}{4\pi}(2.70)$. We check our method by calculating the next-to-leading order
+contribution to the damping rate for the case of QCD with two flavours and
+three coulours. Our result agrees with the result obtained previously in the
+literature. The numerical evaluation of the nlo contribution to the mass is
+left to a future publication.",0610372v1
+2007-03-26,Preheating and Affleck-Dine leptogenesis after thermal inflation,"Previously, we proposed a model of low energy Affleck-Dine leptogenesis in
+the context of thermal inflation. The lepton asymmetry is generated at the end
+of thermal inflation, which occurs at a relatively low energy scale with the
+Hubble parameter somewhere in the range $1 \keV \lesssim H \lesssim 1 \MeV$.
+Thus Hubble damping will be ineffective in bringing the Affleck-Dine field into
+the lepton conserving region near the origin, leaving the possibility that the
+lepton number could be washed out. Previously, we suggested that preheating
+could damp the amplitude of the Affleck-Dine field allowing conservation of the
+lepton number. In this paper, we demonstrate numerically that preheating does
+efficiently damp the amplitude of the Affleck-Dine field and that the lepton
+number is conserved as the result. In addition to demonstrating a crucial
+aspect of our model, it also opens the more general possibility of low energy
+Affleck-Dine baryogenesis.",0703275v1
+1996-03-14,Dissipation and Topologically Massive Gauge Theories in Pseudoeuclidean Plane,"In the pseudo-euclidean metrics Chern-Simons gauge theory in the infrared
+region is found to be associated with dissipative dynamics. In the infrared
+limit the Lagrangian of 2+1 dimensional pseudo-euclidean topologically massive
+electrodynamics has indeed the same form of the Lagrangian of the damped
+harmonic oscillator. On the hyperbolic plane a set of two damped harmonic
+oscillators, each other time-reversed, is shown to be equivalent to a single
+undamped harmonic oscillator. The equations for the damped oscillators are
+proven to be the same as the ones for the Lorentz force acting on two particles
+carrying opposite charge in a constant magnetic field and in the electric
+harmonic potential. This provides an immediate link with Chern-Simons-like
+dynamics of Bloch electrons in solids propagating along the lattice plane with
+hyperbolic energy surface. The symplectic structure of the reduced theory is
+finally discussed in the Dirac constrained canonical formalism.",9603092v1
+2002-08-31,Neutrino damping rate at finite temperature and density,"A first principle derivation is given of the neutrino damping rate in
+real-time thermal field theory. Starting from the discontinuity of the neutrino
+self energy at the two loop level, the damping rate can be expressed as
+integrals over space phase of amplitudes squared, weighted with statistical
+factors that account for the possibility of particle absorption or emission
+from the medium. Specific results for a background composed of neutrinos,
+leptons, protons and neutrons are given. Additionally, for the real part of the
+dispersion relation we discuss the relation between the results obtained from
+the thermal field theory, and those obtained by the thermal average of the
+forward scattering amplitude.",0209006v1
+2004-10-20,Ergodicity for the weakly damped stochastic non-linear Schrödinger equations,"We study a damped stochastic non-linear Schr\""{o}dinger (NLS) equation driven
+by an additive noise. It is white in time and smooth in space. Using a coupling
+method, we establish convergence of the Markovian transition semi-group toward
+a unique invariant probability measure. This kind of method was originally
+developped to prove exponential mixing for strongly dissipative equations such
+as the Navier-Stokes equations. We consider here a weakly dissipative equation,
+the damped nonlinear Schr\""{o}dinger equation in the one dimensional cubic
+case. We prove that the mixing property holds and that the rate of convergence
+to equilibrium is at least polynomial of any power.",0410443v2
+2006-07-30,Non-autonomous dynamics of wave equations with nonlinear damping and critical nonlinearity,"The authors consider non-autonomous dynamical behavior of wave-type
+evolutionary equations with nonlinear damping and critical nonlinearity. These
+type of waves equations are formulated as non-autonomous dynamical systems
+(namely, cocycles). A sufficient and necessary condition for the existence of
+pullback attractors is established for norm-to-weak continuous non-autonomous
+dynamical systems, in terms of pullback asymptotic compactness or pullback
+$\kappa-$contraction criteria. A technical method for verifying pullback
+asymptotic compactness, via contractive functions, is devised. These results
+are then applied to the wave-type evolutionary equations with nonlinear damping
+and critical nonlinearity, to obtain the existence of pullback attractors. The
+required pullback asymptotic compactness for the existence of pullback
+attractors is fulfilled by some new a priori estimates for concrete wave type
+equations arising from applications. Moreover, the pullback
+$\kappa-$contraction criterion for the existence of pullback attractors is of
+independent interest.",0607774v3
+2000-09-28,"Quantization of Damped Harmonic Oscillator, Thermal Field Theories and q-Groups","We study the canonical quantization of the damped harmonic oscillator by
+resorting to the realization of the q-deformation of the Weyl-Heisenberg
+algebra (q-WH) in terms of finite difference operators. We relate the damped
+oscillator hamiltonian to the q-WH algebra and to the squeezing generator of
+coherent states theory. We also show that the q-WH algebra is the natural
+candidate to study thermal field theory. The well known splitting, in the
+infinite volume limit, of the space of physical states into unitarily
+inequivalent representations of the canonical commutation relations is briefly
+commented upon in relation with the von Neumann theorem in quantum mechanics
+and with q-WH algebra.",0009036v1
+2002-02-12,Landau Damping and Coherent Structures in Narrow-Banded 1+1 Deep Water Gravity Waves,"We study the nonlinear energy transfer around the peak of the spectrum of
+surface gravity waves by taking into account nonhomogeneous effects. In the
+narrow-banded approximation the kinetic equation resulting from a
+nonhomogeneous wave field is a Vlasov-Poisson type equation which includes at
+the same time the random version of the Benjamin-Feir instability and the
+Landau damping phenomenon. We analytically derive the values of the Phillips'
+constant $\alpha$ and the enhancement factor $\gamma$ for which the
+narrow-banded approximation of the JONSWAP spectrum is unstable. By performing
+numerical simulations of the nonlinear Schr\""{o}dinger equation we check the
+validity of the prediction of the related kinetic equation. We find that the
+effect of Landau damping is to suppress the formation of coherent structures.
+The problem of predicting freak waves is briefly discussed.",0202026v1
+2005-10-24,Stability of a nonlinear oscillator with random damping,"A noisy damping parameter in the equation of motion of a nonlinear oscillator
+renders the fixed point of the system unstable when the amplitude of the noise
+is sufficiently large. However, the stability diagram of the system can not be
+predicted from the analysis of the moments of the linearized equation. In the
+case of a white noise, an exact formula for the Lyapunov exponent of the system
+is derived. We then calculate the critical damping for which the {\em
+nonlinear} system becomes unstable. We also characterize the intermittent
+structure of the bifurcated state above threshold and address the effect of
+temporal correlations of the noise by considering an Ornstein-Uhlenbeck noise.",0510063v1
+2006-10-20,Vibration of Generalized Double Well Oscillators,"We have applied the Melnikov criterion to examine a global homoclinic
+bifurcation and transition to chaos in a case of a double well dynamical system
+with a nonlinear fractional damping term and external excitation. The usual
+double well Duffing potential having a negative square term and positive
+quartic term has been generalized to a double well potential with a negative
+square term and a positive one with an arbitrary real exponent $q > 2$. We have
+also used a fractional damping term with an arbitrary power $p$ applied to
+velocity which enables one to cover a wide range of realistic damping factors:
+from dry friction $p \to 0$ to turbulent resistance phenomena $p=2$.
+  Using perturbation methods we have found a critical forcing amplitude $\mu_c$
+above which the system may behave chaotically. Our results show that the
+vibrating system is less stable in transition to chaos for smaller $p$
+satisfying an exponential scaling low. The critical amplitude $\mu_c$ as an
+exponential function of $p$.
+  The analytical results have been illustrated by numerical simulations using
+standard nonlinear tools such as
+  Poincare maps and the maximal Lyapunov exponent. As usual for chosen system
+parameters we have identified a chaotic motion above the critical Melnikov
+amplitude $\mu_c$.",0610052v1
+1998-06-18,Relativity Damps OPEP in Nuclear Matter,"Using a relativistic Dirac-Brueckner analysis the OPEP contribution to the
+ground state energy of nuclear matter is studied. In the study the pion is
+derivative-coupled. We find that the role of the tensor force in the saturation
+mechanism is substantially reduced compared to its dominant role in a usual
+nonrelativistic treatment. We show that the damping of derivative-coupled OPEP
+is actually due to the decrease of $M^*/M$ with increasing density. We point
+out that if derivative-coupled OPEP is the preferred form of nuclear effective
+lagrangian nonrelativistic treatment of nuclear matter is in trouble. Lacking
+the notion of $M^*$ it cannot replicate the damping. We suggest an examination
+of the feasibility of using pseudoscalar coupled $\pi$N interaction before
+reaching a final conclusion about nonrelativistic treatment of nuclear matter.",9806054v1
+1999-07-05,Damping of IVGDR - Fermi-liquid or Fermi-gas ?,"Collisional relaxation rates of collective modes in nuclei are calculated
+using the Levinson equation for the reduced density matrix with a memory
+dependent collision term. Linearizing the collision integral two contribution
+have to be distinguished, the one from the quasiparticle energy and the one
+from occupation factors. The first one yields the known Landau formula of zero
+sound damping and the second one leads to the Fermi gas model of Ref.1 with the
+additional factor 3 in front of the frequencies. Adding both contribution we
+obtain a final relaxation rate for the Fermi liquid model. Calculations of the
+temperature dependence of the damping rates and of the shape evolution of IVGDR
+are in good agreement with the experiment and show only minor differences
+between both models.",9907012v1
+2001-01-08,Collisional Damping of Giant Monopole and Quadrupole Resonances,"Collisional damping widths of giant monopole and quadrupole excitations for
+$^{120}$Sn and $^{208}$Pb at zero and finite temperatures are calculated within
+Thomas-Fermi approximation by employing the microscopic in-medium
+cross-sections of Li and Machleidt and the phenomenological Skyrme and Gogny
+forces, and are compared with each other. The results for the collisional
+widths of giant monopole and quadrupole vibrations at zero temperature as a
+function of the mass number show that the collisional damping of giant monopole
+vibrations accounts for about 30-40% of the observed widths at zero
+temperature, while for giant quadrupole vibrations it accounts for only 20-30%
+of the observed widths of zero temperature.",0101016v1
+1998-10-01,Mode-coupling and nonlinear Landau damping effects in auroral Farley-Buneman turbulence,"The fundamental problem of Farley-Buneman turbulence in the auroral
+$E$-region has been discussed and debated extensively in the past two decades.
+In the present paper we intend to clarify the different steps that the auroral
+$E$-region plasma has to undergo before reaching a steady state. The
+mode-coupling calculation, for Farley-Buneman turbulence, is developed in order
+to place it in perspective and to estimate its magnitude relative to the
+anomalous effects which arise through the nonlinear wave-particle interaction.
+This nonlinear effect, known as nonlinear ``Landau damping'' is due to the
+coupling of waves which produces other waves which in turn lose energy to the
+bulk of the particles by Landau damping. This leads to a decay of the wave
+energy and consequently a heating of the plasma. An equation governing the
+evolution of the field spectrum is derived and a physical interpration for each
+of its terms is provided.",9810062v1
+2000-08-20,Fabrication and Tolerance Issues and their Influence on Multi-Bunch Bbu and Emittance Dilution in the Construction of X-Band RDDS Linacs for the NLC,"The main linacs of the Next Linear Collider (NLC) will contain several
+thousand X-band RDDS (Rounded Damped Detuned Structures). The transverse
+wakefield in the structures is reduced by detuning the modal frequencies such
+that they destructively interfere and by four damping manifolds per structure
+which provide weak damping. Errors in the fabrication of the individual cells
+and in the alignment of the cells will reduce the cancellation of the modes.
+Here, we calculate the tolerances on random errors in the synchronous
+frequencies of the cells and the cell-to-cell alignment.",0008198v1
+2003-09-17,A New Damping Mechanism in Non-linear Bubble Dynamics,"Non-linear equations of radial motion of a gas bubble in a compressible
+viscous liquid have been modified considering effects of viscosity and
+compressibility more complete than all previous works. A new set of equations
+has been derived including new terms resulted from consideration of the
+viscosity and compressibility not only at the bubble interface, but also in the
+bulk of liquid. The new equations are two non-linear coupled equations, which
+can not be merged into one equation unlike all previously derived equations.
+Numerical calculations have been performed considering effects of heat and mass
+transfer at the bubble interface. The results indicate that the new terms
+exhibit an important damping role at the collapse, so that their consideration
+dramatically weakens the bubble rebounds after the collapse. Dependence of this
+new damping mechanism to amplitude and frequency of the deriving pressure has
+been investigated.",0309080v1
+2003-11-26,Eigenvector Expansion and Petermann Factor for Ohmically Damped Oscillators,"Correlation functions $C(t) \sim <\phi(t)\phi(0)>$ in ohmically damped
+systems such as coupled harmonic oscillators or optical resonators can be
+expressed as a single sum over modes $j$ (which are not power-orthogonal), with
+each term multiplied by the Petermann factor (PF) $C_j$, leading to ""excess
+noise"" when $|C_j| > 1$. It is shown that $|C_j| > 1$ is common rather than
+exceptional, that $|C_j|$ can be large even for weak damping, and that the PF
+appears in other processes as well: for example, a time-independent
+perturbation $\sim\ep$ leads to a frequency shift $\sim \ep C_j$. The
+coalescence of $J$ ($>1$) eigenvectors gives rise to a critical point, which
+exhibits ""giant excess noise"" ($C_j \to \infty$). At critical points, the
+divergent parts of $J$ contributions to $C(t)$ cancel, while time-independent
+perturbations lead to non-analytic shifts $\sim \ep^{1/J}$.",0311127v2
+2004-04-02,DAFNE injection system upgrade,"High luminosity in DAFNE needs very high electron and positron currents
+stored. A full energy (510 MeV) injection system composed by a full energy
+electron and positron linac and an accumulator-damping ring is presently used.
+The electron and positron beams, alternatively accelerated by the linac, are
+injected and stacked in the accumulator with high efficiency thanks to its
+large acceptance and short damping time. The damped beams are extracted and
+transferred to the main ring through a long transfer line that has been built
+inside already existing buildings. The refill time of the collider is limited
+by the transfer line set-up change between the two different beams modes. In
+this paper a transfer line modification is proposed in order to reduce the
+switch time. A possible injection scheme for the main rings is also described.",0404010v1
+2004-05-05,Langmuir wave self-focusing versus decay instability,"Electron trapping in a finite amplitude Langmuir wave (LW) leads to a
+frequency shift, \Delta\omega_{TP} < 0, and reduced Landau damping. These may
+lead to modulational instability. Its growth rate and damping threshold, due to
+escape of trapped electrons at rate \nu, are calculated for the first time in
+the short wavelength regime. If the background plasma is in thermal
+equilibrium, it is shown that this trapped particle modulational instability
+(TPMI) is not possible when k \lambda_D > 0.46, while for 0.33 < k \lambda_D <
+0.46, TPMI requires that the fluctuation wavevector have a component
+perpendicular to k, the LW wavevector, with \lambda_D the electron Debye
+length. Its nonlinear evolution leads to self-focusing. Comparison is made with
+a re-evaluated LW ion acoustic decay instability (LDI): compared to classical
+estimates, the new LDI threshold is lowered by primary LW \Delta\omega_{TP}
+since frequency matching leads to wavenumber and hence damping reduction of the
+daughter LW. For parameters estimates relevant to a recent stimulated Raman
+scatter experiment (Kline et al., submitted to PRL), the LDI and TPMI
+thresholds cross in the range 0.28 < k \lambda_D < 0.34, consistent with the
+observed LDI regime change. However, if \nu exceeds a critical value, estimated
+to be order 1% of the electron plasma frequency, then TPMI is not possible at
+any wavenumber.",0405015v1
+2005-06-16,Mesoscale Quantization and Self-Organized Stability,"In the world of technology, one of the most important forms of friction is
+that of rolling friction. Yet it is one of the least studied of all the known
+forms of energy dissipation. In the present experiments we investigate the
+oscillatory free-decay of a rigid cube, whose side-length is less than the
+diameter of the rigid cylinder on which it rests. The resulting free-decay is
+one of harmonic motion with damping. The non-dissipative character of the
+oscillation yields to a linear differential equation; however, the damping is
+found to involve more than a deterministic nonlinearity. Dominated by rolling
+friction, the damping is sensitive to the material properties of the contact
+surfaces. For `clean' surfaces of glass on glass, the decay shows features of
+mesoscale quantization and self-organized stability.",0506143v1
+2006-10-31,Ultimate parameters of the photon collider at the ILC,"At linear colliders, the e+e- luminosity is limited by beam-collision
+effects, which determine the required emittances of beams in damping rings
+(DRs). While in gamma-gamma collisions at the photon collider, these effects
+are absent, and so smaller emittances are desirable. In present damping rings
+designs, nominal DR parameters correspond to those required for e+e-
+collisions. In this note, I would like to stress once again that as soon as we
+plan the photon-collider mode of ILC operation, the damping-ring emittances are
+dictated by the photon-collider requirements--namely, they should be as small
+as possible. This can be achieved by adding more wigglers to the DRs; the
+incremental cost is easily justified by a considerable potential improvement of
+the gamma-gamma luminosity. No expert analysis exists as of yet, but it seems
+realistic to obtain a factor five increase of the gamma-gamma luminosity
+compared to the ``nominal'' DR design.",0610285v1
+2006-04-27,On the weak solutions of the McKendrick equation: Existence of demography cycles,"We develop the qualitative theory of the solutions of the McKendrick partial
+differential equation of population dynamics. We calculate explicitly the weak
+solutions of the McKendrick equation and of the Lotka renewal integral equation
+with time and age dependent birth rate. Mortality modulus is considered age
+dependent. We show the existence of demography cycles. For a population with
+only one reproductive age class, independently of the stability of the weak
+solutions and after a transient time, the temporal evolution of the number of
+individuals of a population is always modulated by a time periodic function.
+The periodicity of the cycles is equal to the age of the reproductive age
+class, and a population retains the memory from the initial data through the
+amplitude of oscillations. For a population with a continuous distribution of
+reproductive age classes, the amplitude of oscillation is damped. The
+periodicity of the damped cycles is associated with the age of the first
+reproductive age class. Damping increases as the dispersion of the fertility
+function around the age class with maximal fertility increases. In general, the
+period of the demography cycles is associated with the time that a species
+takes to reach the reproductive maturity.",0604035v2
+1999-03-05,Exact Diagonalization of Two Quantum Models for the Damped Harmonic Oscillator,"The damped harmonic oscillator is a workhorse for the study of dissipation in
+quantum mechanics. However, despite its simplicity, this system has given rise
+to some approximations whose validity and relation to more refined descriptions
+deserve a thorough investigation. In this work, we apply a method that allows
+us to diagonalize exactly the dissipative Hamiltonians that are frequently
+adopted in the literature. Using this method we derive the conditions of
+validity of the rotating-wave approximation (RWA) and show how this approximate
+description relates to more general ones. We also show that the existence of
+dissipative coherent states is intimately related to the RWA. Finally, through
+the evaluation of the dynamics of the damped oscillator, we notice an important
+property of the dissipative model that has not been properly accounted for in
+previous works; namely, the necessity of new constraints to the application of
+the factorizable initial conditions.",9903022v2
+1999-04-06,Nonclassical correlations in damped quantum solitons,"Using cumulant expansion in Gaussian approximation, the internal quantum
+statistics of damped soliton-like pulses in Kerr media are studied numerically,
+considering both narrow and finite bandwidth spectral pulse components. It is
+shown that the sub-Poissonian statistics can be enhanced, under certain
+circumstances, by absorption, which damps out some destructive interferences.
+Further, it is shown that both the photon-number correlation and the
+correlation of the photon-number variance between different pulse components
+can be highly nonclassical even for an absorbing fiber. Optimum frequency
+windows are determined in order to realize strong nonclassical behavior, which
+offers novel possibilities of using solitons in optical fibers as a source of
+nonclassically correlated light beams.",9904017v2
+1999-04-19,Quantum theory of fluctuations in a cold damped accelerometer,"We present a quantum network approach to real high sensitivity measurements.
+Thermal and quantum fluctuations due to active as well as passive elements are
+taken into account. The method is applied to the analysis of the capacitive
+accelerometer using the cold damping technique, developed for fundamental
+physics in space by ONERA and the ultimate limits of this instrument are
+discussed. It is confirmed in this quantum analysis that the cold damping
+technique allows one to control efficiently the test mass motion without
+degrading the noise level.",9904073v2
+2000-07-04,Stochastic limit approximation for rapidly decaying systems,"The stochastic limit approximation method for ``rapid'' decay is presented,
+where the damping rate \gamma is comparable to the system frequency \Omega,
+i.e., \gamma \sim \Omega, whereas the usual stochastic limit approximation is
+applied only to the weak damping situation \gamma << \Omega. The key formulas
+for rapid decay are very similar to those for weak damping, but the dynamics is
+quite different. From a microscopic Hamiltonian, the spin-boson model, a Bloch
+equation containing two independent time scales is derived. This is a useful
+method to extract the minimal dissipative dynamics at high temperature kT >>
+\hbar\Omega and the master equations obtained are of the Lindblad form even for
+the Caldeira-Leggett model. The validity of the method is confirmed by
+comparing the master equation derived through this method with the exact one.",0007007v2
+2000-08-01,Full mechanical characterization of a cold damped mirror,"We describe an experiment in which we have used a cold damping feedback
+mechanism to reduce the thermal noise of a mirror around its mechanical
+resonance frequency. The monitoring of the brownian motion of the mirror allows
+to apply an additional viscous force without any thermal fluctuations
+associated. This scheme has been experimentally implemented with the radiation
+pressure of an intensity-modulated laser beam. Large noise reductions, up to 30
+dB, have been obtained. We have also checked the mechanical response of the
+cold damped mirror, and monitored its transient evolution between the cooled
+regime and the room temperature equilibrium. A simple theoretical model allows
+to fully explain the experimental results. A possible application to the active
+cooling of the violin modes in a gravitational-wave interferometer is
+discussed.",0008004v1
+2003-11-05,Exact decoherence to pointer states in free open quantum systems is universal,"In this paper it is shown that exact decoherence to minimal uncertainty
+Gaussian pointer states is generic for free quantum particles coupled to a heat
+bath. More specifically, the paper is concerned with damped free particles
+linearly coupled under product initial conditions to a heat bath at arbitrary
+temperature, with arbitrary coupling strength and spectral densities covering
+the Ohmic, subohmic, and supraohmic regime. Then it is true that there exists a
+time t_c such that for times t>t_c the state can always be exactly represented
+as a mixture (convex combination) of particular minimal uncertainty Gaussian
+states, regardless of and independent from the initial state. This exact
+`localisation' is hence not a feature specific to high temperatures and weak
+damping limit, but is rather a generic property of damped free particles.",0311022v3
+2004-07-30,Kraus representation of damped harmonic oscillator and its application,"By definition, the Kraus representation of a harmonic oscillator suffering
+from the environment effect, modeled as the amplitude damping or the phase
+damping, is directly given by a simple operator algebra solution. As examples
+and applications, we first give a Kraus representation of a single qubit whose
+computational basis states are defined as bosonic vacuum and single particle
+number states. We further discuss the environment effect on qubits whose
+computational basis states are defined as the bosonic odd and even coherent
+states. The environment effects on entangled qubits defined by two different
+kinds of computational basis are compared with the use of fidelity.",0407263v2
+2005-01-31,"The non dissipative damping of the Rabi oscillations as a ""which-path"" information","Rabi oscillations may be viewed as an interference phenomenon due to a
+coherent superposition of different quantum paths, like in the Young's two-slit
+experiment. The inclusion of the atomic external variables causes a non
+dissipative damping of the Rabi oscillations. More generally, the atomic
+translational dynamics induces damping in the correlation functions which
+describe non classical behaviors of the field and internal atomic variables,
+leading to the separability of these two subsystems. We discuss on the
+possibility of interpreting this intrinsic decoherence as a ""which-way""
+information effect and we apply to this case a quantitative analysis of the
+complementarity relation as introduced by Englert [Phys. Rev. Lett.
+\textbf{77}, 2154 (1996)].",0501181v1
+2006-01-12,Driven harmonic oscillator as a quantum simulator for open systems,"We show theoretically how a driven harmonic oscillator can be used as a
+quantum simulator for non-Markovian damped harmonic oscillator. In the general
+framework, the results demonstrate the possibility to use a closed system as a
+simulator for open quantum systems. The quantum simulator is based on sets of
+controlled drives of the closed harmonic oscillator with appropriately tailored
+electric field pulses. The non-Markovian dynamics of the damped harmonic
+oscillator is obtained by using the information about the spectral density of
+the open system when averaging over the drives of the closed oscillator. We
+consider single trapped ions as a specific physical implementation of the
+simulator, and we show how the simulator approach reveals new physical insight
+into the open system dynamics, e.g. the characteristic quantum mechanical
+non-Markovian oscillatory behavior of the energy of the damped oscillator,
+usually obtained by the non-Lindblad-type master equation, can have a simple
+semiclassical interpretation.",0601081v2
+2006-07-31,Nonadiabatic Transitions for a Decaying Two-Level-System: Geometrical and Dynamical Contributions,"We study the Landau-Zener Problem for a decaying two-level-system described
+by a non-hermitean Hamiltonian, depending analytically on time. Use of a
+super-adiabatic basis allows to calculate the non-adiabatic transition
+probability P in the slow-sweep limit, without specifying the Hamiltonian
+explicitly. It is found that P consists of a ``dynamical'' and a
+``geometrical'' factors. The former is determined by the complex adiabatic
+eigenvalues E_(t), only, whereas the latter solely requires the knowledge of
+\alpha_(+-)(t), the ratio of the components of each of the adiabatic
+eigenstates. Both factors can be split into a universal one, depending only on
+the complex level crossing points, and a nonuniversal one, involving the full
+time dependence of E_(+-)(t). This general result is applied to the
+Akulin-Schleich model where the initial upper level is damped with damping
+constant $\gamma$. For analytic power-law sweeps we find that Stueckelberg
+oscillations of P exist for gamma smaller than a critical value gamma_c and
+disappear for gamma > gamma_c. A physical interpretation of this behavior will
+be presented by use of a damped harmonic oscillator.",0607221v1
+2007-05-05,Damped Corrections to Inflationary Spectra from a Fluctuating Cutoff,"We reconsider trans-Planckian corrections to inflationary spectra by taking
+into account a physical effect which has been overlooked and which could have
+important consequences. We assume that the short length scale characterizing
+the new physics is endowed with a finite width, the origin of which could be
+found in quantum gravity. As a result, the leading corrections responsible for
+superimposed osillations in the CMB temperature anisotropies are generically
+damped by the blurring of the UV scale. To determine the observational
+ramifications of this damping, we compare it to that which effectively occurs
+when computing the angular power spectrum of temperature anisotropies. The
+former gives an overall change of the oscillation amplitudes whereas the latter
+depends on the angular scale. Therefore, in principle they could be
+distinguished. In any case, the observation of superimposed oscillations would
+place tight constraint on the variance of the UV cutoff.",0705.0747v1
+2007-05-10,Magnetization oscillations induced by a spin-polarized current in a point-contact geometry: mode hopping and non-linear damping effects,"In this paper we study magnetization excitations induced in a thin extended
+film by a spin-polarized dc-current injected through a point contact in the
+current-perpendicular-to-plane (CPP) geometry. Using full-scale micromagnetic
+simulations, we demonstrate that in addition to the oscillations of the
+propagating wave type, there exist also two localized oscillation modes. The
+first localized mode has a relatively homogeneous magnetization structure of
+its kernel and corresponds to the so called 'bullet' predicted analytically by
+Slavin and Tiberkevich (Phys. Rev. Lett., 95 (2005) 237201). Magnetization
+pattern of the second localized mode kernel is highly inhomogeneous, leading to
+a much smaller power of magnetoresistance oscillations caused by this mode. We
+have also studied the influence of a non-linear damping for this system and
+have found the following main qualitative effects: (i) the appearance of
+frequency jumps within the existence region of the propagating wave mode and
+(ii) the narrowing of the current region where the 'bullet' mode exists, until
+this mode completely disappears for a sufficiently strong non-linear damping.",0705.1515v1
+2007-05-27,Amplitude Damping for single-qubit System with single-qubit mixed-state Environment,"We study a generalized amplitude damping channel when environment is
+initially in the single-qubit mixed state. Representing the affine
+transformation of the generalized amplitude damping by a three-dimensional
+volume, we plot explicitly the volume occupied by the channels simulatable by a
+single-qubit mixed-state environment. As expected, this volume is embedded in
+the total volume by the channels which is simulated by two-qubit enviroment.
+The volume ratio is approximately 0.08 which is much smaller than 3/8, the
+volume ratio for generalized depolarizing channels.",0705.3952v3
+2007-06-01,The geometrical quantity in damped wave equations on a square,"The energy in a square membrane $\Omega$ subject to constant viscous damping
+on a subset $\omega\subset \Omega$ decays exponentially in time as soon as
+$\omega$ satisfies a geometrical condition known as the ""Bardos-Lebeau-Rauch""
+condition. The rate $\tau(\omega)$ of this decay satisfies $\tau(\omega)= 2
+\min(-\mu(\omega), g(\omega))$ (see Lebeau [Math. Phys. Stud. 19 (1996)
+73-109]). Here $\mu(\omega)$ denotes the spectral abscissa of the damped wave
+equation operator and $g(\omega)$ is a number called the geometrical quantity
+of $\omega$ and defined as follows. A ray in $\Omega$ is the trajectory
+generated by the free motion of a mass-point in $\Omega$ subject to elastic
+reflections on the boundary. These reflections obey the law of geometrical
+optics. The geometrical quantity $g(\omega)$ is then defined as the upper limit
+(large time asymptotics) of the average trajectory length. We give here an
+algorithm to compute explicitly $g(\omega)$ when $\omega$ is a finite union of
+squares.",0706.0172v1
+2007-06-08,Kinetic-Ion Simulations Addressing Whether Ion Trapping Inflates Stimulated Brillouin Backscattering Reflectivities,"An investigation of the possible inflation of stimulated Brillouin
+backscattering (SBS) due to ion kinetic effects is presented using
+electromagnetic particle simulations and integrations of three-wave
+coupled-mode equations with linear and nonlinear models of the nonlinear ion
+physics. Electrostatic simulations of linear ion Landau damping in an ion
+acoustic wave, nonlinear reduction of damping due to ion trapping, and
+nonlinear frequency shifts due to ion trapping establish a baseline for
+modeling the electromagnetic SBS simulations. Systematic scans of the laser
+intensity have been undertaken with both one-dimensional particle simulations
+and coupled-mode-equations integrations, and two values of the electron-to-ion
+temperature ratio (to vary the linear ion Landau damping) are considered. Three
+of the four intensity scans have evidence of SBS inflation as determined by
+observing more reflectivity in the particle simulations than in the
+corresponding three-wave mode-coupling integrations with a linear ion-wave
+model, and the particle simulations show evidence of ion trapping.",0706.1236v1
+2007-06-29,Driving-dependent damping of Rabi oscillations in two-level semiconductor systems,"We propose a mechanism to explain the nature of the damping of Rabi
+oscillations with increasing driving-pulse area in localized semiconductor
+systems, and have suggested a general approach which describes a coherently
+driven two-level system interacting with a dephasing reservoir. Present
+calculations show that the non-Markovian character of the reservoir leads to
+the dependence of the dephasing rate on the driving-field intensity, as
+observed experimentally. Moreover, we have shown that the damping of Rabi
+oscillations might occur as a result of different dephasing mechanisms for both
+stationary and non-stationary effects due to coupling to the environment.
+Present calculated results are found in quite good agreement with available
+experimental measurements.",0706.4372v1
+2007-08-06,Collisionsless amplifying of longitudinal electron waves in two-stream plasma,"To better understanding the principal features of collisionless
+damping/growing plasma waves we have implemented a demonstrative calculation
+for the simplest cases of electron waves in two-stream plasmas with the
+delta-function type electron velocity distribution function of each of the
+streams with velocities v(1) and v(2). The traditional dispersion equation is
+reduced to an algebraic 4th order equation, for which numerical solutions are
+presented for a variant of equal stream densities. In the case of uniform
+half-infinite slab one finds two dominant type solutions: non-damping forward
+waves and forward complex conjugated exponentially both damping and growing
+waves. Beside it in this case there is no necessity of calculation any
+logarithmically divergent indefinite integrals. The possibility of wave
+amplifying might be useful in practical applications.",0708.0767v1
+2007-08-09,The Highly Damped Quasinormal Modes of Extremal Reissner-Nordström and Reissner-Nordström-de Sitter Black Holes,"We analyze in detail the highly damped quasinormal modes of $D$-dimensional
+extremal Reissner-Nordstr$\ddot{\rm{o}}$m and
+Reissner-Nordstr$\ddot{\rm{o}}$m-de Sitter black holes. We only consider the
+extremal case where the event horizon and the Cauchy inner horizon coincide. We
+show that, even though the topology of the Stokes/anti-Stokes lines in the
+extremal case is different than the non-extremal case, the highly damped
+quasinormal mode frequencies of extremal black holes match exactly with the
+extremal limit of the non-extremal black hole quasinormal mode frequencies.",0708.1333v2
+2007-08-28,Resonantly damped surface and body MHD waves in a solar coronal slab with oblique propagation,"The theory of magnetohydrodynamic (MHD) waves in solar coronal slabs in a
+zero-$\beta$ configuration and for parallel propagation of waves does not allow
+the existence of surface waves. When oblique propagation of perturbations is
+considered both surface and body waves are able to propagate. When the
+perpendicular wave number is larger than a certain value, the body kink mode
+becomes a surface wave. In addition, a sausage surface mode is found below the
+internal cut-off frequency. When non-uniformity in the equilibrium is included,
+surface and body modes are damped due to resonant absorption. In this paper,
+first, a normal-mode analysis is performed and the period, the damping rate,
+and the spatial structure of eigenfunctions are obtained. Then, the
+time-dependent problem is solved, and the conditions under which one or the
+other type of mode is excited are investigated.",0708.3783v1
+2007-09-11,Teleportation of qubit states through dissipative channels: Conditions for surpassing the no-cloning limit,"We investigate quantum teleportation through dissipative channels and
+calculate teleportation fidelity as a function of damping rates. It is found
+that the average fidelity of teleportation and the range of states to be
+teleported depend on the type and rate of the damping in the channel. Using the
+fully entangled fraction, we derive two bounds on the damping rates of the
+channels: one is to beat the classical limit and the second is to guarantee the
+non-existence of any other copy with better fidelity. Effect of the initially
+distributed maximally entangled state on the process is presented; and the
+concurrence and the fully entangled fraction of the shared states are
+discussed. We intend to show that prior information on the dissipative channel
+and the range of qubit states to be teleported is helpful for the evaluation of
+the success of teleportation, where success is defined as surpassing the
+fidelity limit imposed by the fidelity of 1-to-2 optimal cloning machine for
+the specific range of qubits.",0709.1662v1
+2007-10-03,Global stability of travelling fronts for a damped wave equation with bistable nonlinearity,"We consider the damped wave equation \alpha u_tt + u_t = u_xx - V'(u) on the
+whole real line, where V is a bistable potential. This equation has travelling
+front solutions of the form u(x,t) = h(x-st) which describe a moving interface
+between two different steady states of the system, one of which being the
+global minimum of V. We show that, if the initial data are sufficiently close
+to the profile of a front for large |x|, the solution of the damped wave
+equation converges uniformly on R to a travelling front as t goes to plus
+infinity. The proof of this global stability result is inspired by a recent
+work of E. Risler and relies on the fact that our system has a Lyapunov
+function in any Galilean frame.",0710.0794v1
+2007-12-19,Cosmic String Dynamics and Evolution in Warped Spacetime,"We study the dynamics and evolution of Nambu-Goto strings in a warped
+spacetime, where the warp factor is a function of the internal coordinates
+giving rise to a `throat' region. The microscopic equations of motion for
+strings in this background include potential and friction terms, which attract
+the strings towards the bottom of the warping throat. However, by considering
+the resulting macroscopic equations for the velocities of strings in the
+vicinity of the throat, we note the absence of enough classical damping to
+guarantee that the strings actually reach the warped minimum and stabilise
+there. Instead, our classical analysis supports a picture in which the strings
+experience mere deflections and bounces around the tip, rather than strongly
+damped oscillations. Indeed, 4D Hubble friction is inefficient in the internal
+dimensions and there is no other classical mechanism known, which could provide
+efficient damping. These results have potentially important implications for
+the intercommuting probabilities of cosmic superstrings.",0712.3224v2
+2007-12-20,The Critical Exponent of the Fractional Langevin Equation is $α_c\approx 0.402$,"We investigate the dynamical phase diagram of the fractional Langevin
+equation and show that critical exponents mark dynamical transitions in the
+behavior of the system. For a free and harmonically bound particle the critical
+exponent $\alpha_c= 0.402\pm 0.002$ marks a transition to a non-monotonic
+under-damped phase. The critical exponent $\alpha_{R}=0.441...$ marks a
+transition to a resonance phase, when an external oscillating field drives the
+system. Physically, we explain these behaviors using a cage effect, where the
+medium induces an elastic type of friction. Phase diagrams describing the
+under-damped, the over-damped and critical frequencies of the fractional
+oscillator, recently used to model single protein experiments, show behaviors
+vastly different from normal.",0712.3407v1
+2008-01-24,Particle Acceleration by Fast Modes in Solar Flares,"We address the problem of particle acceleration in solar flares by fast modes
+which may be excited during the reconnection and undergo cascade and are
+subjected to damping. We extend the calculations beyond quasilinear
+approximation and compare the acceleration and scattering by transit time
+damping and gyroresonance interactions. We find that the acceleration is
+dominated by the so called transit time damping mechanism. We estimate the
+total energy transferred into particles, and show that our approach provides
+sufficiently accurate results We compare this rate with energy loss rate.
+Scattering by fast modes appears to be sufficient to prevent the protons from
+escaping the system during the acceleration. Confinement of electrons, on the
+other hand, requires the existence of plasma waves. Electrons can be
+accelerated to GeV energies through the process described here for solar flare
+conditions.",0801.3786v2
+2008-02-07,Analysis of squeal noise and mode coupling instabilities including damping and gyroscopic effects,"This paper deals with an audible disturbance known as automotive clutch
+squeal noise from the viewpoint of friction-induced mode coupling instability.
+Firstly, an auto-coupling model is presented showing a non-conservative
+circulatory effect originating from friction forces. Secondly, the stability of
+an equilibrium is investigated by determining the eigenvalues of the system
+linearized equations. The effects of the circulatory and gyroscopic actions are
+examined analytically and numerically to determine their influence on the
+stability region. Separate and combined effects are analysed with and without
+structural damping and important information is obtained on the role of each
+parameter and their interactions regarding overall stability. Not only is
+structural damping shown to be of primary importance, as reported in many
+previous works, this article also highlights a particular relationship with
+gyroscopic effects. A method of optimizing both the stability range and its
+robustness with respect to uncertainty on system parameters is discussed after
+which practical design recommendations are given.",0802.0923v1
+2008-02-12,Nonlinear Saturation of g-modes in Proto-Neutron Stars: Quieting the Acoustic Engine,"According to Burrows et al.'s acoustic mechanism for core-collapse supernova
+explosions, the primary, l=1, g-mode in the core of the proto-neutron star is
+excited to an energy of ~ 10^{50} ergs and damps by the emission of sound
+waves. Here we calculate the damping of the primary mode by the parametric
+instability, i.e., by nonlinear, 3-mode coupling between the low-order primary
+mode and pairs of high-order g-modes. We show that the primary mode is strongly
+coupled to highly resonant, neutrino damped pairs with n>10; such short
+wavelength interactions cannot be resolved in the simulations. We find that the
+parametric instability saturates the primary mode energy at ~10^{48} ergs, well
+below the energy needed to drive an explosion. We therefore conclude that
+acoustic power is unlikely to be energetically significant in core-collapse
+supernova explosions.",0802.1522v3
+2008-03-03,Damped harmonic oscillator interpretation of the soft-state power spectra of Cyg X-1,"We develop a model of an accretion disc in which the variability induced at a
+given radius is governed by a damped harmonic oscillator at the corresponding
+epicyclic frequency. That variability induces both linear and non-linear
+responses in the locally emitted radiation. The total observed variability of a
+source is the sum of these contributions over the disc radius weighted by the
+energy dissipation rate at each radius. It is shown that this simple model,
+which effectively has only three parameters including the normalization, can
+explain the range of the power spectra observed from Cyg X-1 in the soft state.
+Although a degeneracy between the black hole mass and the strength of the
+damping does not allow a unique determination of the mass, we can still
+constrain it to <16--20 solar masses. We also show that our model preserves the
+observed linear rms-flux relationship even in the presence of the non-linear
+flux response.",0803.0238v2
+2008-03-05,The Secular Evolution of a Close Ring-Satellite System: The Excitation of Spiral Density Waves at a Nearby Gap Edge,"The Lagrange planetary equations are used to study to secular evolution of a
+small, eccentric satellite that orbits within a narrow gap in a broad,
+self-gravitating planetary ring. These equations show that the satellite's
+secular perturbations of the ring will excite a very long-wavelength spiral
+density wave that propagates away from the gap's outer edge. The amplitude of
+these waves, as well as their dispersion relation, are derived here. That
+dispersion relation reveals that a planetary ring can sustain two types of
+density waves: long waves that, in Saturn's A ring, would have wavelengths of
+order 100 km, and short waves that tend to be very nonlinear and are expected
+to quickly damp. The excitation of these waves also transports angular momentum
+from the ring to the satellite in a way that damps the satellite's eccentricity
+e, which also tends to reduce the amplitude of subsequent waves. The rate of
+eccentricity damping due to this wave action is then compared to the rates at
+which the satellite's Lindblad and corotation resonances alter the satellite's
+e. These results are then applied to the gap-embedded Saturnian satellites Pan
+and Daphnis, and the long-term stability of their eccentricities is assessed.",0803.0576v1
+2008-03-06,Hypersound damping in vitreous silica measured by picosecond acoustics,"The attenuation of longitudinal acoustic phonons up to frequencies nearing
+250 GHz is measured in vitreous silica with a picosecond optical technique.
+Taking advantage of interferences on the probe beam, difficulties encountered
+in early pioneering experiments are alleviated. Sound damping at 250 GHz and
+room temperature is consistent with relaxation dominated by anharmonic
+interactions with the thermal bath, extending optical Brillouin scattering
+data. Our result is at variance with claims of a recent deep-UV experiment
+which reported a rapid damping increase beyond 100 GHz. A comprehensive picture
+of the frequency dependence of sound attenuation in $v$-SiO$_2$ can be
+proposed.",0803.0832v1
+2008-03-07,Resonance distribution in open quantum chaotic systems,"In order to study the resonance spectra of chaotic cavities subject to some
+damping (which can be due to absorption or partial reflection at the
+boundaries), we use a model of damped quantum maps. In the high-frequency
+limit, the distribution of (quantum) decay rates is shown to cluster near a
+``typical'' value, which is larger than the classical decay rate of the
+corresponding damped ray dynamics. The speed of this clustering may be quite
+slow, which could explain why it has not been detected in previous numerical
+data.",0803.1075v4
+2008-04-03,Single flux quantum circuits with damping based on dissipative transmission lines,"We propose and demonstrate the functioning of a special Rapid Single Flux
+Quantum (RSFQ) circuit with frequency-dependent damping. This damping is
+achieved by shunting individual Josephson junctions by pieces of open-ended RC
+transmission lines. Our circuit includes a toggle flip-flop cell, Josephson
+transmission lines transferring single flux quantum pulses to and from this
+cell, as well as DC/SFQ and SFQ/DC converters. Due to the desired
+frequency-dispersion in the RC line shunts which ensures sufficiently low noise
+at low frequencies, such circuits are well-suited for integrating with the
+flux/phase Josephson qubit and enable its efficient control.",0804.0442v1
+2008-05-14,"Reconciling results of LSND, MiniBooNE and other experiments with soft decoherence","We propose an explanation of the LSND signal via quantum-decoherence of the
+mass states, which leads to damping of the interference terms in the
+oscillation probabilities. The decoherence parameters as well as their energy
+dependence are chosen in such a way that the damping affects only oscillations
+with the large (atmospheric) $\Delta m^2$ and rapidly decreases with the
+neutrino energy. This allows us to reconcile the positive LSND signal with
+MiniBooNE and other null-result experiments. The standard explanations of
+solar, atmospheric, KamLAND and MINOS data are not affected. No new particles,
+and in particular, no sterile neutrinos are needed. The LSND signal is
+controlled by the 1-3 mixing angle $\theta_{13}$ and, depending on the degree
+of damping, yields $0.0014 < \sin^2\theta_{13} < 0.034$ at $3\sigma$. The
+scenario can be tested at upcoming $\theta_{13}$ searches: while the comparison
+of near and far detector measurements at reactors should lead to a null-result
+a positive signal for $\theta_{13}$ is expected in long-baseline accelerator
+experiments. The proposed decoherence may partially explain the results of
+Gallium detector calibrations and it can strongly affect supernova neutrino
+signals.",0805.2098v1
+2008-06-02,Observations of Solar Doppler Shift Oscillations with the EUV Imaging Spectrometer on Hinode,"Damped Doppler shift oscillations have been observed in emission lines from
+ions formed at flare temperatures with the Solar Ultraviolet Measurements of
+Emitted Radiation spectrometer on the Solar and Heliospheric Observatory and
+with the Bragg Crystal Spectrometer on Yohkoh. This Letter reports the
+detection of low-amplitude damped oscillations in coronal emission lines formed
+at much lower temperatures observed with the EUV Imaging Spectrometer on the
+Hinode satellite. The oscillations have an amplitude of about 2 km/s, and a
+period of around 35 min. The decay times show some evidence for a temperature
+dependence with the lowest temperature of formation emission line (Fe XII
+195.12 Angstroms) exhibiting a decay time of about 43 min, while the highest
+temperature of formation emission line (Fe XV 284.16 Angstroms) shows no
+evidence for decay over more than two periods of the oscillation. The data
+appear to be consistent with slow magnetoacoustic standing waves, but may be
+inconsistent with conductive damping.",0806.0265v1
+2008-07-07,Using squeezed field to preserve two-atom entanglement against spontaneous emissions,"Tunable interaction between two atoms in a cavity is realized by interacting
+the two atoms with an extra controllable single-mode squeezed field. Such a
+controllable interaction can be further used to control entanglement between
+the two atoms against amplitude damping decoherence caused by spontaneous
+emissions. For the independent amplitude damping decoherence channel,
+entanglement will be lost completely without controls, while it can be
+partially preserved by the proposed strategy. For the collective amplitude
+damping decoherence channel, our strategy can enhance the entanglement compared
+with the uncontrolled case when the entanglement of the uncontrolled stationary
+state is not too large.",0807.0965v2
+2008-07-17,Connecting high-redshift galaxy populations through observations of local Damped Lyman Alpha dwarf galaxies,"I report on observations of the z=0.01 dwarf galaxy SBS1543+593 which is
+projected onto the background QSO HS1543+5921. As a star-forming galaxy first
+noted in emission, this dwarf is playing a pivotal role in our understanding of
+high-redshift galaxy populations, because it also gives rise to a Damped Lyman
+Alpha system. This enabled us to analyze, for the first time, the chemical
+abundance of $\alpha$ elements in a Damped Lyman Alpha galaxy using both,
+emission and absorption diagnostics. We find that the abundances agree with one
+another within the observational uncertainties. I discuss the implications of
+this result for the interpretation of high-redshift galaxy observations. A
+catalog of dwarf-galaxy--QSO projections culled from the Sloan Digital Sky
+Survey is provided to stimulate future work.",0807.2853v1
+2008-07-23,"Damped driven coupled oscillators: entanglement, decoherence and the classical limit","The interaction of (two-level) Rydberg atoms with dissipative QED cavity
+fields can be described classically or quantum mechanically, even for very low
+temperatures and mean number of photons, provided the damping constant is large
+enough. We investigate the quantum-classical border, the entanglement and
+decoherence of an analytically solvable model, analog to the atom-cavity
+system, in which the atom (field) is represented by a (driven and damped)
+harmonic oscillator. The maximum value of entanglement is shown to depend on
+the initial state and the dissipation-rate to coupling-constant ratio. While in
+the original model the atomic entropy never grows appreciably (for large
+dissipation rates), in our model it reaches a maximum before decreasing.
+Although both models predict small values of entanglement and dissipation, for
+fixed times of the order of the inverse of the coupling constant and large
+dissipation rates, these quantities decrease faster, as a function of the ratio
+of the dissipation rate to the coupling constant, in our model.",0807.3715v1
+2008-07-26,A Monte Carlo Method for Modeling Thermal Damping: Beyond the Brownian-Motion Master Equation,"The ""standard"" Brownian motion master equation, used to describe thermal
+damping, is not completely positive, and does not admit a Monte Carlo method,
+important in numerical simulations. To eliminate both these problems one must
+add a term that generates additional position diffusion. He we show that one
+can obtain a completely positive simple quantum Brownian motion, efficiently
+solvable, without any extra diffusion. This is achieved by using a stochastic
+Schroedinger equation (SSE), closely analogous to Langevin's equation, that has
+no equivalent Markovian master equation. Considering a specific example, we
+show that this SSE is sensitive to nonlinearities in situations in which the
+master equation is not, and may therefore be a better model of damping for
+nonlinear systems.",0807.4211v3
+2008-07-31,Finite-dimensional attractors for the quasi-linear strongly-damped wave equation,"We present a new method of investigating the so-called quasi-linear strongly
+damped wave equations $$ \partial_t^2u-\gamma\partial_t\Delta_x u-\Delta_x
+u+f(u)= \nabla_x\cdot \phi'(\nabla_x u)+g $$ in bounded 3D domains. This method
+allows us to establish the existence and uniqueness of energy solutions in the
+case where the growth exponent of the non-linearity $\phi$ is less than 6 and
+$f$ may have arbitrary polynomial growth rate. Moreover, the existence of a
+finite-dimensional global and exponential attractors for the solution semigroup
+associated with that equation and their additional regularity are also
+established. In a particular case $\phi\equiv0$ which corresponds to the
+so-called semi-linear strongly damped wave equation, our result allows to
+remove the long-standing growth restriction $|f(u)|\leq C(1+ |u|^5)$.",0807.5078v1
+2008-08-01,Field-Driven Domain-Wall Dynamics in GaMnAs Films with Perpendicular Anisotropy,"We combine magneto-optical imaging and a magnetic field pulse technique to
+study domain wall dynamics in a ferromagnetic (Ga,Mn)As layer with
+perpendicular easy axis. Contrary to ultrathin metallic layers, the depinning
+field is found to be smaller than the Walker field, thereby allowing for the
+observation of the steady and precessional flow regimes. The domain wall width
+and damping parameters are determined self-consistently. The damping, 30 times
+larger than the one deduced from ferromagnetic resonance, is shown to
+essentially originate from the non-conservation of the magnetization modulus.
+An unpredicted damping resonance and a dissipation regime associated with the
+existence of horizontal Bloch lines are also revealed.",0808.0119v1
+2008-08-11,Effect of frequency and temperature on microwave-induced magnetoresistance oscillations in two-dimensional electron systems,"Experimental results on microwave-induced magnetoresistance oscillation in
+two-dimensional electron systems show a similar behavior of these systems
+regarding temperature and microwave frequency. It is found that these
+oscillations tend to quench when frequency or temperature increase, approaching
+magnetoresistance to the response of the dark system. In this work we show that
+this experimental behavior can be addressed on the same theoretical basis.
+Microwave radiation forces the electron orbits to move back and forth being
+damped by interaction with the lattice. We show that this damping depends
+dramatically on microwave frequency and also on temperature. An increase in
+frequency or temperature gives rise to an increase in the lattice damping
+producing eventually a quenching effect in the magnetoresistance oscillations.",0808.1489v1
+2009-01-14,"Brownian motion with respect to time-changing Riemannian metrics, applications to Ricci flow","We generalize Brownian motion on a Riemannian manifold to the case of a
+family of metrics which depends on time. Such questions are natural for
+equations like the heat equation with respect to time dependent Laplacians
+(inhomogeneous diffusions). In this paper we are in particular interested in
+the Ricci flow which provides an intrinsic family of time dependent metrics. We
+give a notion of parallel transport along this Brownian motion, and establish a
+generalization of the Dohrn-Guerra or damped parallel transport, Bismut
+integration by part formulas, and gradient estimate formulas. One of our main
+results is a characterization of the Ricci flow in terms of the damped parallel
+transport. At the end of the paper we give an intrinsic definition of the
+damped parallel transport in terms of stochastic flows, and derive an intrinsic
+martingale which may provide information about singularities of the flow.",0901.1999v2
+2009-01-26,Damping of sound waves in superfluid nucleon-hyperon matter of neutron stars,"We consider sound waves in superfluid nucleon-hyperon matter of massive
+neutron-star cores. We calculate and analyze the speeds of sound modes and
+their damping times due to the shear viscosity and non-equilibrium weak
+processes of particle transformations. For that, we employ the dissipative
+relativistic hydrodynamics of a superfluid nucleon-hyperon mixture, formulated
+recently [M.E. Gusakov and E.M. Kantor, Phys. Rev. D78, 083006 (2008)]. We
+demonstrate that the damping times of sound modes calculated using this
+hydrodynamics and the ordinary (nonsuperfluid) one, can differ from each other
+by several orders of magnitude.",0901.4108v1
+2009-03-02,Attenuation and damping of electromagnetic fields: Influence of inertia and displacement current,"New results for attenuation and damping of electromagnetic fields in rigid
+conducting media are derived under the conjugate influence of inertia due to
+charge carriers and displacement current. Inertial effects are described by a
+relaxation time for the current density in the realm of an extended Ohm's law.
+The classical notions of poor and good conductors are rediscussed on the basis
+of an effective electric conductivity, depending on both wave frequency and
+relaxation time. It is found that the attenuation for good conductors at high
+frequencies depends solely on the relaxation time. This means that the
+penetration depth saturates to a minimum value at sufficiently high
+frequencies. It is also shown that the actions of inertia and displacement
+current on damping of magnetic fields are opposite to each other. That could
+explain why the classical decay time of magnetic fields scales approximately as
+the diffusion time. At very small length scales, the decay time could be given
+either by the relaxation time or by a fraction of the diffusion time, depending
+whether inertia or displacement current, respectively, would prevail on
+magnetic diffusion.",0903.0210v1
+2009-04-06,Scrutinizing single-qubit quantum channels: Theory and experiment with trapped ions,"We report experimental implementation of various types of qubit channels
+using an individual trapped ion. We analyzed experimental data and we performed
+tomographic reconstruction of quantum channels based on these data.
+Specifically, we studied phase damping channels, where the damping acts either
+in the xy-plane of the Bloch sphere or in an arbitrary plane that includes the
+origin of the Bloch sphere. We also experimentally realized and consequently
+analyzed quantum channels that in addition to phase damping affect also a
+polarization rotation. We used three reconstruction schemes for estimation of
+quantum channels from experimental data: (1) a linear inverse method, (2) a
+maximum likelihood estimation, and (3) a constrained maximum likelihood
+estimation. We took into account realistic experimental conditions where
+imperfect test-state preparations and biased measurements are incorporated into
+the estimation schemes. As a result we found that imperfections present in the
+process of preparation of test states and as well as in measurements of the
+considered ion trap system do not limit the control of the implementation of
+the desired channel. Even imperfect preparation of test state and subsequent
+measurements still provide sufficient resources for the complete
+quantum-channel tomography.",0904.0923v1
+2009-06-04,Viscous cavity damping of a microlever in a simple fluid,"We consider the problem of oscillation damping in air of a thermally actuated
+microlever as it is gradually approached towards an infinite wall in parallel
+geometry. As the gap is decreased from 20 nm down to 400 nm, we observe the
+increasing damping of the lever Brownian motion in the fluid laminar regime.
+This manifests itself as a linear decrease with distance of the lever quality
+factor accompanied by a dramatic softening of its resonance, and eventually
+leads to the freezing of the CL oscillation. We are able to quantitatively
+explain this behavior by analytically solving the Navier-Stokes equation with
+perfect slip boundary conditions. Our findings may have implications for
+microfluidics and micro- nano-electromechanical applications.",0906.0782v1
+2009-06-19,Wakefield damping for the CLIC crab cavity,"A crab cavity is required in the CLIC to allow effective head-on collision of
+bunches at the IP. A high operating frequency is preferred as the deflection
+voltage required for a given rotation angle and the RF phase tolerance for a
+crab cavity are inversely proportional to the operating frequency. The short
+bunch spacing of the CLIC scheme and the high sensitivity of the crab cavity to
+dipole kicks demand very high damping of the inter-bunch wakes, the major
+contributor to the luminosity loss of colliding bunches. This paper
+investigates the nature of the wakefields in the CLIC crab cavity and the
+possibility of using various damping schemes to suppress them effectively.",0906.3593v1
+2009-07-06,Non-Fermi liquid behavior due to U(1) gauge field in two dimensions,"We study the damping rate of massless Dirac fermions due to the U(1) gauge
+field in (2+1)-dimensional quantum electrodynamics. In the absence of a Maxwell
+term for the gauge field, the fermion damping rate
+$\mathrm{Im}\Sigma(\omega,T)$ is found to diverge in both perturbative and
+self-consistent results. In the presence of a Maxwell term, there is still
+divergence in the perturbative results for $\mathrm{Im}\Sigma(\omega,T)$. Once
+the Maxwell term is included into the self-consistent equations for fermion
+self-energy and vacuum polarization functions, the fermion damping rate is free
+of divergence and exhibits non-Fermi liquid behavior:
+$\mathrm{Im}\Sigma(\omega,T) \propto \mathrm{max}(\sqrt{\omega},\sqrt{T})$.",0907.1022v3
+2009-08-19,Nonlinear viscoelastic wave propagation: an extension of Nearly Constant Attenuation (NCQ) models,"Hysteretic damping is often modeled by means of linear viscoelastic
+approaches such as ""nearly constant Attenuation (NCQ)"" models. These models do
+not take into account nonlinear effects either on the stiffness or on the
+damping, which are well known features of soil dynamic behavior. The aim of
+this paper is to propose a mechanical model involving nonlinear viscoelastic
+behavior for isotropic materials. This model simultaneously takes into account
+nonlinear elasticity and nonlinear damping. On the one hand, the shear modulus
+is a function of the excitation level; on the other, the description of
+viscosity is based on a generalized Maxwell body involving non-linearity. This
+formulation is implemented into a 1D finite element approach for a dry soil.
+The validation of the model shows its ability to retrieve low amplitude ground
+motion response. For larger excitation levels, the analysis of seismic wave
+propagation in a nonlinear soil layer over an elastic bedrock leads to results
+which are physically satisfactory (lower amplitudes, larger time delays, higher
+frequency content).",0908.2715v2
+2009-08-26,Influence of an external magnetic field on forced turbulence in a swirling flow of liquid metal,"We report an experimental investigation on the influence of an external
+magnetic field on forced 3D turbulence of liquid gallium in a closed vessel. We
+observe an exponential damping of the turbulent velocity fluctuations as a
+function of the interaction parameter N (ratio of Lorentz force over inertial
+terms of the Navier-Stokes equation). The flow structures develop some
+anisotropy but do not become bidimensional. From a dynamical viewpoint, the
+damping first occurs homogeneously over the whole spectrum of frequencies. For
+larger values of N, a very strong additional damping occurs at the highest
+frequencies. However, the injected mechanical power remains independent of the
+applied magnetic field. The simultaneous measurement of induced magnetic field
+and electrical potential differences shows a very weak correlation between
+magnetic field and velocity fluctuations. The observed reduction of the
+fluctuations is in agreement with a previously proposed mechanism for the
+saturation of turbulent dynamos and with the order of magnitude of the Von
+Karman Sodium dynamo magnetic field.",0908.3821v1
+2009-09-30,Electronic damping of molecular motion at metal surfaces,"A method for the calculation of the damping rate due to electron-hole pair
+excitation for atomic and molecular motion at metal surfaces is presented. The
+theoretical basis is provided by Time Dependent Density Functional Theory
+(TDDFT) in the quasi-static limit and calculations are performed within a
+standard plane-wave, pseudopotential framework. The artificial periodicity
+introduced by using a super-cell geometry is removed to derive results for the
+motion of an isolated atom or molecule, rather than for the coherent motion of
+an ordered over-layer. The algorithm is implemented in parallel, distributed
+across both ${\bf k}$ and ${\bf g}$ space, and in a form compatible with the
+CASTEP code. Test results for the damping of the motion of hydrogen atoms above
+the Cu(111) surface are presented.",0909.5495v1
+2009-10-14,Constraint on the growth factor of the cosmic structure from the damping of the baryon acoustic oscillation signature,"We determine a constraint on the growth factor by measuring the damping of
+the baryon acoustic oscillations in the matter power spectrum using the Sloan
+Digital Sky Survey luminous red galaxy sample. The damping of the BAO is
+detected at the one sigma level. We obtain \sigma_8D_1(z=0.3) =
+0.42^{+0.34}_{-0.28} at the 1\sigma statistical level, where \sigma_8 is the
+root mean square overdensity in a sphere of radius 8h^{-1}Mpc and D_1(z) is the
+growth factor at redshift z. The above result assumes that other parameters are
+fixed and the cosmology is taken to be a spatially flat cold dark matter
+universe with the cosmological constant.",0910.2513v1
+2009-10-27,On the Interpretation of Magnetic Helicity Signatures in the Dissipation Range of Solar Wind Turbulence,"Measurements of small-scale turbulent fluctuations in the solar wind find a
+non-zero right-handed magnetic helicity. This has been interpreted as evidence
+for ion cyclotron damping. However, theoretical and empirical evidence suggests
+that the majority of the energy in solar wind turbulence resides in low
+frequency anisotropic kinetic Alfven wave fluctuations that are not subject to
+ion cyclotron damping. We demonstrate that a dissipation range comprised of
+kinetic Alfven waves also produces a net right-handed fluctuating magnetic
+helicity signature consistent with observations. Thus, the observed magnetic
+helicity signature does not necessarily imply that ion cyclotron damping is
+energetically important in the solar wind.",0910.5023v1
+2009-12-08,Coupling Photosphere and Corona: Linear and Turbulent Regimes,"In a recent work Grappin et al. [1] have shown that low- frequency movements
+can be transmitted from one footpoint to the other along a magnetic loop, thus
+mimicking a friction effect of the corona on the photosphere, and invalidating
+the line-tying approximation. We consider here successively the effect of high
+frequencies and turbulent damping on the process. We use a very simple
+atmospheric model which allows to study analytically the laminar case, and to
+study the turbulent case both using simple phenomenological arguments and a
+more sophisticated turbulence model [2]. We find that, except when turbulent
+damping is such that all turbulence is damped during loop traversal, coupling
+still occurs between distant footpoints, and moreover the coronal field induced
+by photospheric movements saturates at finite values.",0912.1497v1
+2009-12-16,The role of $r$-mode damping in the thermal evolution of neutron stars,"The thermal evolution of neutron stars (NSs) is investigated by coupling with
+the evolution of $\textit{r}$-mode instability that is described by a second
+order model.The heating effect due to shear viscous damping of the
+$\textit{r}$-modes enables us to understand the high temperature of two young
+pulsars (i.e., PSR B0531+21 and RX J0822-4300) in the framework of the simple
+$npe$ NS model, without superfluidity or exotic particles.Moreover, the light
+curves predicted by the model within an acceptable parameter regime may
+probably cover all of the young and middle-aged pulsars in the $\lg
+T_s^{\infty}-\lg t$ panel, and an artificially strong $p$ superfluidity invoked
+in some early works is not needed here. Additionally, by considering the
+radiative viscous damping of the $\textit{r}$-modes, a surprising extra cooling
+effect is found, which can even exceed the heating effect sometimes although
+plays an ignorable role in the thermal history.",0912.3052v1
+2009-12-25,Noisy non-transitive quantum games,"We study the effect of quantum noise in 3 by 3 entangled quantum games. By
+considering different noisy quantum channels we analyze that how a two-player,
+three-strategy Rock-Scissor-Paper game is influenced by the quantum noise. We
+consider the winning non-transitive strategies R, S and P such as R beats S, S
+beats P, and P beats R. The game behaves as a noiseless game for maximum value
+of the quantum noise parameter. It is seen that Alice's payoff is heavily
+influenced by the depolarizing noise as compared to the amplitude damping
+noise. Depolarizing channel causes a monotonic decrease in players payoffs as
+we increase the amount of of quantum noise. In case of amplitude damping
+channel, the Alice's payoff function reaches its minimum for alpha=0.5 and is
+symmetrical. This means that larger values of quantum noise influence the game
+weakly. On the other hand, phase damping channel does not influence the game's
+payoff. Furthermore, the game's Nash equilibrium and non-transitive character
+of the game are not affected under the influence of quantum noise.",0912.4961v1
+2010-01-26,Damping in high-frequency metallic nanomechanical resonators,"We have studied damping in polycrystalline Al nanomechanical resonators by
+measuring the temperature dependence of their resonance frequency and quality
+factor over a temperature range of 0.1 - 4 K. Two regimes are clearly
+distinguished with a crossover temperature of 1 K. Below 1 K we observe a
+logarithmic temperature dependence of the frequency and linear dependence of
+damping that cannot be explained by the existing standard models. We attribute
+these phenomena to the effect of the two-level systems characterized by the
+unexpectedly long (at least two orders of magnitude longer) relaxation times
+and discuss possible microscopic models for such systems. We conclude that the
+dynamics of the two-level systems is dominated by their interaction with
+one-dimensional phonon modes of the resonators.",1001.4612v1
+2010-04-28,Inviscid dynamical structures near Couette flow,"Consider inviscid fluids in a channel {-1<y<1}. For the Couette flow
+v_0=(y,0), the vertical velocity of solutions to the linearized Euler equation
+at v_0 decays in time. At the nonlinear level, such inviscid damping has not
+been proved. First, we show that in any (vorticity) H^{s}(s<(3/2)) neighborhood
+of Couette flow, there exist non-parallel steady flows with arbitrary minimal
+horizontal period. This implies that nonlinear inviscid damping is not true in
+any (vorticity) H^{s}(s<(3/2)) neighborhood of Couette flow and for any
+horizontal period. Indeed, the long time behavior in such neighborhoods are
+very rich, including nontrivial steady flows, stable and unstable manifolds of
+nearby unstable shears. Second, in the (vorticity) H^{s}(s>(3/2)) neighborhood
+of Couette, we show that there exist no non-parallel steadily travelling flows
+v(x-ct,y), and no unstable shears. This suggests that the long time dynamics in
+H^{s}(s>(3/2)) neighborhoods of Couette might be much simpler. Such contrasting
+dynamics in H^{s} spaces with the critical power s=(3/2) is a truly nonlinear
+phenomena, since the linear inviscid damping near Couette is true for any
+initial vorticity in L^2.",1004.5149v1
+2010-06-14,Parallel electric field amplification by phase-mixing of Alfven waves,"Previous numerical studies have identified ""phase mixing"" of low-frequency
+Alfven waves as a mean of parallel electric field amplification and
+acceleration of electrons in a collisionless plasma. Theoretical explanations
+are given of how this produces an amplification of the parallel electric field,
+and as a consequence, also leads to enhanced collisionless damping of the wave
+by energy transfer to the electrons. Our results are based on the properties of
+the Alfven waves in a warm plasma which are obtained from drift-kinetic theory,
+in particular, the rate of their electron Landau damping. Phase mixing in a
+collisionless low-$\beta$ plasma proceeds in a manner very similar to the
+visco-resistive case, except for the fact that electron Landau damping is the
+primary energy dissipation channel. The time and length scales involved are
+evaluated. We also focus on the evolution of the parallel electric field and
+calculate its maximum value in the course of its amplification.",1006.2729v1
+2010-07-19,Anomalously large damping of long-wavelength quasiparticles caused by long-range interaction,"We demonstrate that long-range interaction in a system can lead to a very
+strong interaction between long-wavelength quasiparticles and make them heavily
+damped. In particular, we discuss magnon spectrum using 1/S expansion in 3D
+Heisenberg ferromagnet (FM) with arbitrary small dipolar forces at T<<T_C. We
+obtain that a fraction of long-wavelength magnons with energies e_k<T has
+anomalously large damping G_k (ratio G_k/e_k reaches 0.3 for certain k). This
+effect is observed both in quantum and classical FMs. Remarkably, this result
+contradicts expectation of the quasiparticle concept according which a weakly
+excited state of a many-body system can be represented as a collection of
+weakly interacting elementary excitations. Particular materials are pointed out
+which are suitable for corresponding experiments.",1007.3081v2
+2010-07-29,The Quasinormal Mode Spectrum of a Kerr Black Hole in the Eikonal Limit,"It is well established that the response of a black hole to a generic
+perturbation is characterized by a spectrum of damped resonances, called
+quasinormal modes; and that, in the limit of large angular momentum ($l \gg
+1$), the quasinormal mode frequency spectrum is related to the properties of
+unstable null orbits. In this paper we develop an expansion method to explore
+the link. We obtain new closed-form approximations for the lightly-damped part
+of the spectrum in the large-$l$ regime. We confirm that, at leading order in
+$l$, the resonance frequency is linked to the orbital frequency, and the
+resonance damping to the Lyapunov exponent, of the relevant null orbit. We go
+somewhat further than previous studies to establish (i) a spin-dependent
+correction to the frequency at order $1 / l$ for equatorial ($m = \pm l$)
+modes, and (ii) a new result for polar modes ($m = 0$). We validate the
+approach by testing the closed-form approximations against frequencies obtained
+numerically with Leaver's method.",1007.5097v1
+2010-08-30,"Caldeira-Leggett Model, Landau Damping, and the Vlasov-Poisson System","The Caldeira-Leggett Hamiltonian (Eq. (1) below) describes the interaction of
+a discrete harmonic oscillator with a continuous bath of harmonic oscillators.
+This system is a standard model of dissipation in macroscopic low temperature
+physics, and has applications to superconductors, quantum computing, and
+macroscopic quantum tunneling. The similarities between the Caldeira-Leggett
+model and the linearized Vlasov-Poisson equation are analyzed, and it is shown
+that the damping in the Caldeira-Leggett model is analogous to that of Landau
+damping in plasmas [1]. An invertible linear transformation [2, 3] is presented
+that converts solutions of the Caldeira-Leggett model into solutions of the
+linearized Vlasov-Poisson system.",1008.5190v1
+2010-09-09,A number-conserving linear response study of low-velocity ion stopping in a collisional magnetized classical plasma,"The results of a theoretical investigation on the low-velocity stopping power
+of the ions moving in a magnetized collisional plasma are presented. The
+stopping power for an ion is calculated employing linear response theory using
+the dielectric function approach. The collisions, which leads to a damping of
+the excitations in the plasma, is taken into account through a
+number-conserving relaxation time approximation in the linear response
+function. In order to highlight the effects of collisions and magnetic field we
+present a comparison of our analytical and numerical results obtained for a
+nonzero damping or magnetic field with those for a vanishing damping or
+magnetic field. It is shown that the collisions remove the anomalous friction
+obtained previously [Nersisyan et al., Phys. Rev. E 61, 7022 (2000)] for the
+collisionless magnetized plasmas at low ion velocities. One of major objectives
+of this study is to compare and contrast our theoretical results with those
+obtained through a novel diffusion formulation based on Dufty-Berkovsky
+relation evaluated in magnetized one-component plasma models framed on target
+ions and electrons.",1009.1700v1
+2010-10-03,A High Phase Advance Damped and Detuned Structure for the Main Linacs of Clic,"The main accelerating structures for the CLIC are designed to operate at an
+average accelerating gradient of 100 MV/m. The accelerating frequency has been
+optimised to 11.994 GHz with a phase advance of 2{\pi}/3 of the main
+accelerating mode. The moderately damped and detuned structure (DDS) design is
+being studied as an alternative to the strongly damped WDS design. Both these
+designs are based on the nominal accelerating phase advance. Here we explore
+high phase advance (HPA) structures in which the group velocity of the rf
+fields is reduced compared to that of standard (2{\pi}/3) structures. The
+electrical breakdown strongly depends on the fundamental mode group velocity.
+Hence it is expected that electrical breakdown is less likely to occur in the
+HPA structures. We report on a study of both the fundamental and dipole modes
+in a CLIC_DDS_HPA structure, designed to operate at 5{\pi}/6 phase advance per
+cell. Higher order dipole modes in both the standard and HPA structures are
+also studied.",1010.0438v1
+2010-10-23,Environmental influences on Quantum Monty Hall problem,"We reformulate the quantum Monty Hall problem in the presence of decoherence.
+The decoherence destroys the fairness of the game. A new Nash equilibrium for a
+particular strategy profile in the presence of decoherence emerges. It is shown
+that in the presence of decoherence under the action of amplitude damping
+channel, Bob's winning probability is always higher than three-forth,
+irrespective of Alice's strategy, if he does not switch to the other door and
+always wins for a fully decohered case of the channel. Depolarizing channel
+damps up Bob's winning probability and gets better off if he sticks to his
+current selection. Phase damping channel leaves the winning probability
+unaffected. Unlike the classical and the quantum forms of the game, Bob's
+dominant strategy in the presence of decoherence is not switching.",1010.4875v2
+2010-12-14,Controlling transfer of quantum correlations among bi-partitions of a composite quantum system by combining noisy environments,"The correlation dynamics is investigated for various bi-partitions of a
+composite system consisting of two qubits, and two independent and
+non-identical noisy environments. The two qubits have no direct interaction
+with each other and locally interact with their environments. Classical and
+quantum correlations including entanglement are initially prepared only between
+the two qubits. We find that, contrary to the identical noisy environment case,
+the entanglement and quantum correlation transfer directions can be controlled
+by combining different noisy environments. The amplitude damping environment
+determines whether there exists entanglement transfer among the bi-partitions
+of a composite system. When one qubit is coupled to an amplitude damping
+environment but another one to a bit-flip one, we find a very interesting
+result that all the quantum and classical correlations, and even the
+entanglement, originally existing between the qubits, can be completely
+transferred without any loss to the qubit coupled to the bit-flip environment
+and the amplitude-damping environment. We also notice that it is possible to
+distinguish the quantum correlation from the classical correlation and
+entanglement by combining different noisy environments.",1012.3033v1
+2010-12-22,Viscous damping of r-modes: Small amplitude instability,"We study the viscous damping of r-modes of compact stars and analyze in
+detail the regions where small amplitude modes are unstable to the emission of
+gravitational radiation. We present general expressions for the viscous damping
+times for arbitrary forms of interacting dense matter and derive general
+semi-analytic results for the boundary of the instability region. These results
+show that many aspects, like in particular the physically important minima of
+the instability boundary, are surprisingly insensitive to detailed microscopic
+properties of the considered form of matter. Our general expressions are
+applied to the cases of hadronic stars, strange stars, and hybrid stars, and we
+focus on equations of state that are compatible with the recent measurement of
+a heavy compact star. We find that hybrid stars with a sufficiently small core
+can ""masquerade"" as neutron stars and feature an instability region that is
+indistinguishable from that of a neutron star, whereas neutron stars with a
+core density high enough to allow direct Urca reactions feature a notch on the
+right side of the instability region.",1012.4883v2
+2010-12-27,Phenomenology of Current-Induced Dynamics in Antiferromagnets,"We derive a phenomenological theory of current-induced staggered
+magnetization dynamics in antiferromagnets. The theory captures the reactive
+and dissipative current-induced torques and the conventional effects of
+magnetic fields and damping. A Walker ansatz describes the dc current-induced
+domain-wall motion when there is no dissipation. If magnetic damping and
+dissipative torques are included, the Walker ansatz remains robust when the
+domain-wall moves slowly. As in ferromagnets, the domain-wall velocity is
+proportional to the ratio between the dissipative-torque and the magnetization
+damping. In addition, a current-driven antiferromagnetic domain-wall acquires a
+net magnetic moment.",1012.5655v2
+2011-02-02,"Harmonic Oscillator in Heat Bath: Exact simulation of time-lapse-recorded data, exact analytical benchmark statistics","The stochastic dynamics of the damped harmonic oscillator in a heat bath is
+simulated with an algorithm that is exact for time steps of arbitrary size.
+Exact analytical results are given for correlation functions and power spectra
+in the form they acquire when computed from experimental time-lapse recordings.
+Three applications are discussed: (i) Effects of finite sampling-rate and
+-time, described exactly here, are similar for other stochastic dynamical
+systems-e.g. motile micro-organisms and their time-lapse recorded trajectories.
+(ii) The same statistics is satisfied by any experimental system to the extent
+it is interpreted as a damped harmonic oscillator at finite temperature-such as
+an AFM cantilever. (iii) Three other models of fundamental interest are
+limiting cases of the damped harmonic oscillator at finite temperature; it
+consequently bridges their differences and describes effects of finite sampling
+rate and sampling time for these models as well. Finally, we give a brief
+discussion of nondimensionalization.",1102.0524v1
+2011-02-04,A symmetry trip from Caldirola to Bateman damped systems,"For the Caldirola-Kanai system, describing a quantum damped harmonic
+oscillator, a couple of constant-of-motion operators generating the Heisenberg
+algebra can be found. The inclusion of the standard time evolution symmetry in
+this algebra for damped systems, in a unitary manner, requires a non-trivial
+extension of this basic algebra and hence the physical system itself.
+Surprisingly, this extension leads directly to the so-called Bateman's dual
+system, which now includes a new particle acting as an energy reservoir. The
+group of symmetries of the dual system is presented, as well as a quantization
+that implies, in particular, a first-order Schr\""odinger equation. The usual
+second-order equation and the inclusion of the original Caldirola-Kanai model
+in Bateman's system are also discussed.",1102.0990v1
+2011-03-03,Determination of the pairing state in iron-based superconductors through neutron scattering,"We calculate the spin susceptibility in the s_{+-} and s_{++} superconducting
+states of the iron pnictides using the effective five orbital model and
+considering the quasiparticle damping. For the experimentally evaluated
+magnitude of the quasiparticle damping and the superconducting gap, the results
+at the wave vector ~ (pi,0) show that the s_{+-} state is more consistent with
+the neutron scattering experiments, while for larger quasiparticle damping and
+the superconducting gap, the s_{++} state can be more consistent. To
+distinguish between two cases that reproduce the experiments at the wave vector
+~ (pi,0), we propose to investigate experimentally the wave vector ~ (pi,pi).",1103.0586v2
+2011-03-03,Transmission of classical and quantum information through a quantum memory channel with damping,"We consider the transfer of classical and quantum information through a
+memory amplitude damping channel. Such a quantum channel is modeled as a damped
+harmonic oscillator, the interaction between the information carriers - a train
+of qubits - and the oscillator being of the Jaynes-Cummings kind. We prove that
+this memory channel is forgetful, so that quantum coding theorems hold for its
+capacities. We analyze entropic quantities relative to two uses of this
+channel. We show that memory effects improve the channel aptitude to transmit
+both classical and quantum information, and we investigate the mechanism by
+which memory acts in changing the channel transmission properties.",1103.0747v2
+2011-03-18,Time-periodic solitons in a damped-driven nonlinear Schrödinger equation,"Time-periodic solitons of the parametrically driven damped nonlinear
+Schr\""odinger equation are obtained as solutions of the boundary-value problem
+on a two-dimensional spatiotemporal domain. We follow the transformation of the
+periodic solitons as the strength of the driver is varied. The resulting
+bifurcation diagrams provide a natural explanation for the overall form and
+details of the attractor chart compiled previously via direct numerical
+simulations. In particular, the diagrams confirm the occurrence of the
+period-doubling transition to temporal chaos for small values of dissipation
+and the absence of such transitions for larger dampings. This difference in the
+soliton's response to the increasing driving strength can be traced to the
+difference in the radiation frequencies in the two cases. Finally, we relate
+the soliton's temporal chaos to the homoclinic bifurcation.",1103.3604v1
+2011-04-30,Resonantly Damped Propagating Kink Waves in Longitudinally Stratified Solar Waveguides,"It has been shown that resonant absorption is a robust physical mechanism to
+explain the observed damping of magnetohydrodynamic (MHD) kink waves in the
+solar atmosphere due to naturally occurring plasma inhomogeneity in the
+direction transverse to the direction of the magnetic field. Theoretical
+studies of this damping mechanism were greatly inspired by the first
+observations of post-flare standing kink modes in coronal loops using the
+Transition Region And Coronal Explorer (TRACE). More recently, these studies
+have been extended to explain the attenuation of propagating coronal kink waves
+observed by the Coronal Multi-Channel Polarimeter (CoMP). In the present study,
+for the first time we investigate the properties of propagating kink waves in
+solar waveguides including the effects of both longitudinal and transverse
+plasma inhomogeneity. Importantly, it is found that the wavelength is only
+dependent on the longitudinal stratification and the amplitude is simply a
+product of the two effects. In light of these results the advancement of solar
+atmospheric magnetoseismology by exploiting high spatial/temporal resolution
+observations of propagating kink waves in magnetic waveguides to determine the
+length scales of the plasma inhomogeneity along and transverse to the direction
+of the magnetic field is discussed.",1105.0067v1
+2011-05-05,The effect of twisted magnetic field on the resonant absorption of MHD waves in coronal loops,"The standing quasi modes in a cylindrical incompressible flux tube with
+magnetic twist that undergoes a radial density structuring is considered in
+ideal magnetohydrodynamics (MHD). The radial structuring is assumed to be a
+linearly varying density profile. Using the relevant connection formulae, the
+dispersion relation for the MHD waves is derived and solved numerically to
+obtain both the frequencies and damping rates of the fundamental and
+first-overtone modes of both the kink (m=1) and fluting (m=2,3) waves. It was
+found that a magnetic twist will increase the frequencies, damping rates and
+the ratio of the oscillation frequency to the damping rate of these modes. The
+period ratio P_1/P_2 of the fundamental and its first-overtone surface waves
+for kink (m=1) and fluting (m=2,3) modes is lower than 2 (the value for an
+untwisted loop) in the presence of twisted magnetic field. For the kink modes,
+particularly, the magnetic twists B_{\phi}/B_z=0.0065 and 0.0255 can achieve
+deviations from 2 of the same order of magnitude as in the observations.
+Furthermore, for the fundamental kink body waves, the frequency bandwidth
+increases with increasing the magnetic twist.",1105.1120v1
+2011-05-05,Interpreting Graph Cuts as a Max-Product Algorithm,"The maximum a posteriori (MAP) configuration of binary variable models with
+submodular graph-structured energy functions can be found efficiently and
+exactly by graph cuts. Max-product belief propagation (MP) has been shown to be
+suboptimal on this class of energy functions by a canonical counterexample
+where MP converges to a suboptimal fixed point (Kulesza & Pereira, 2008).
+  In this work, we show that under a particular scheduling and damping scheme,
+MP is equivalent to graph cuts, and thus optimal. We explain the apparent
+contradiction by showing that with proper scheduling and damping, MP always
+converges to an optimal fixed point. Thus, the canonical counterexample only
+shows the suboptimality of MP with a particular suboptimal choice of schedule
+and damping. With proper choices, MP is optimal.",1105.1178v1
+2011-05-14,Crossovers in the non-Markovian dynamics of two-qubit entanglements,"We study the entanglement dynamics of two non-interacting, spatially
+separated qubits subject to local environment noises. Based on exactly solvable
+models for non-Markovian amplitude damping and phase damping noises, we are
+able to analyze the entanglement dynamics of the two qubits for different
+coupling bandwidths and different detunings. We show that entanglement
+oscillations can occur for both amplitude and phase damping noises. Moreover,
+we demonstrate that changing the coupling bandwidth can lead to crossover
+between dissipative and non-dissipative entanglement dynamics, while varying
+the detuning controls the crossover between strong and weak coupling limits.
+Our findings can help provide a synthesized picture for the entanglement
+dynamics of two qubits subject to local environment noises.",1105.2859v2
+2011-06-17,Controlling Excitations Inversion of a Cooper Pair Box Interacting with a Nanomechanical Resonator,"We investigate the action of time dependent detunings upon the excitation
+inversion of a Cooper pair box interacting with a nanomechanical resonator. The
+method employs the Jaynes-Cummings model with damping, assuming different decay
+rates of the Cooper pair box and various fixed and t-dependent detunings. It is
+shown that while the presence of damping plus constant detunings destroy the
+collapse/revival effects, convenient choices of time dependent detunings allow
+one to reconstruct such events in a perfect way. It is also shown that the mean
+excitation of the nanomechanical resonator is more robust against damping of
+the Cooper pair box for convenient values of t-dependent detunings.",1106.3379v1
+2011-07-04,An HI column density threshold for cold gas formation in the Galaxy,"We report the discovery of a threshold in the HI column density of Galactic
+gas clouds below which the formation of the cold phase of HI is inhibited. This
+threshold is at $N_{HI} = 2 \times 10^{20}$ per cm$^{2}$; sightlines with lower
+HI column densities have high spin temperatures (median $T_s \sim 1800$ K),
+indicating low fractions of the cold neutral medium (CNM), while sightlines
+with $N_{HI} \ge 2 \times 10^{20}$ per cm$^{2}$ have low spin temperatures
+(median $T_s \sim 240$ K), implying high CNM fractions. The threshold for CNM
+formation is likely to arise due to inefficient self-shielding against
+ultraviolet photons at lower HI column densities. The threshold is similar to
+the defining column density of a damped Lyman-$\alpha$ absorber; this indicates
+a physical difference between damped and sub-damped Lyman-$\alpha$ systems,
+with the latter class of absorbers containing predominantly warm gas.",1107.0744v2
+2011-07-24,Traveling kinks in cubic nonlinear Ginzburg-Landau equations,"Nonlinear cubic Euler-Lagrange equations of motion in the traveling variable
+are usually derived from Ginzburg-Landau free energy functionals frequently
+encountered in several fields of physics. Many authors considered in the past
+damped versions of such equations with the damping term added by hand
+simulating the friction due to the environment. It is known that even in this
+damped case kink solutions can exist. By means of a factorization method, we
+provide analytic formulas for several possible kink solutions of such equations
+of motion in the undriven and constant field driven cases, including the
+recently introduced Riccati parameter kinks which were not considered
+previously in such a context. The latter parameter controls the delay of the
+switching stage of the kinks",1107.4773v4
+2011-08-22,On conditions for asymptotic stability of dissipative infinite-dimensional systems with intermittent damping,"We study the asymptotic stability of a dissipative evolution in a Hilbert
+space subject to intermittent damping. We observe that, even if the
+intermittence satisfies a persistent excitation condition, if the Hilbert space
+is infinite-dimensional then the system needs not being asymptotically stable
+(not even in the weak sense). Exponential stability is recovered under a
+generalized observability inequality, allowing for time-domains that are not
+intervals. Weak asymptotic stability is obtained under a similarly generalized
+unique continuation principle. Finally, strong asymptotic stability is proved
+for intermittences that do not necessarily satisfy some persistent excitation
+condition, evaluating their total contribution to the decay of the trajectories
+of the damped system. Our results are discussed using the example of the wave
+equation, Schr\""odinger's equation and, for strong stability, also the special
+case of finite-dimensional systems.",1108.4327v2
+2011-08-26,Aligned Major Axes in a Planetary System without Tidal Evolution: The 61 Virginis example,"Tidal damping of one of the orbits in a planetary system can lead to aligned
+major-axes (the so-called ""fixed-point"" condition), but currently aligned major
+axes do not necessarily imply such a history. An example is the nominal orbital
+solution for the 61 Virginis system where two orbits librate about alignment,
+but evaluation of the eigenmodes of the secular theory shows it could not be
+the result of tidal damping but rather of initial conditions. Nevertheless, the
+amplitudes of the eigenmodes suggest that this system may have undergone some
+degree of tidal damping.",1108.5369v1
+2011-09-09,Optimal linear optical implementation of a single-qubit damping channel,"We experimentally demonstrate a single-qubit decohering quantum channel using
+linear optics. We implement the channel, whose special cases include both the
+amplitude-damping channel and the bit-flip channel, using a single, static
+optical setup. Following a recent theoretical result [M. Piani et al., Phys.
+Rev. A, 84, 032304 (2011)], we realize the channel in an optimal way,
+maximizing the probability of success, i.e., the probability for the photonic
+qubit to remain in its encoding. Using a two-photon entangled resource, we
+characterize the channel using ancilla-assisted process tomography and find
+average process fidelities of 0.9808 \pm 0.0002 and 0.9762 \pm 0.0002 for
+amplitude-damping and the bit-flip case, respectively.",1109.2070v1
+2011-11-20,Detection of picosecond magnetization dynamics of 50 nm magnetic dots down to the single dot regime,"We report an all-optical time-domain detection of picosecond magnetization
+dynamics of arrays of 50 nm Ni80Fe20 (permalloy) dots down to the single
+nanodot regime. In the single nanodot regime the dynamics reveals one dominant
+resonant mode corresponding to the edge mode of the 50 nm dot with slightly
+higher damping than that of the unpatterned thin film. With the increase in
+areal density of the array both the precession frequency and damping increases
+significantly due to the increase in magnetostatic interactions between the
+nanodots and a mode splitting and sudden jump in apparent damping are observed
+at an edge-to-edge separation of 50 nm.",1111.4625v1
+2011-12-02,An energy-based computational method in the analysis of the transmission of energy in a chain of coupled oscillators,"In this paper we study the phenomenon of nonlinear supratransmission in a
+semi-infinite discrete chain of coupled oscillators described by modified
+sine-Gordon equations with constant external and internal damping, and subject
+to harmonic external driving at the end. We develop a consistent and
+conditionally stable finite-difference scheme in order to analyze the effect of
+damping in the amount of energy injected in the chain of oscillators; numerical
+bifurcation analyses to determine the dependence of the amplitude at which
+supratransmission first occurs with respect to the frequency of the driving
+oscillator are carried out in order to show the consequences of damping on
+harmonic phonon quenching and the delay of appearance of critical amplitude.",1112.0581v1
+2012-01-09,Universal response of optimal granular damping devices,"Granular damping devices constitute an emerging technology for the
+attenuation of vibrations based on the dissipative nature of particle
+collisions. We show that the performance of such devices is independent of the
+material properties of the particles for working conditions where damping is
+optimal. Even the suppression of a dissipation mode (collisional or frictional)
+is unable to alter the response. We explain this phenomenon in terms of the
+inelastic collapse of granular materials. These findings provide a crucial
+standpoint for the design of such devices in order to achieve the desired low
+maintenance feature that makes particle dampers particularly suitable to harsh
+environments.",1201.1866v2
+2012-01-09,Radiative energy loss reduction in an absorptive plasma,"The influence of the damping of radiation on the radiative energy loss
+spectrum of a relativistic charge in an infinite, absorptive plasma is studied.
+We find increasing reduction of the spectrum with increasing damping. Our
+studies, which represent an Abelian approximation for the colour charge
+dynamics in the quark-gluon plasma, may influence the analysis of jet quenching
+phenomena observed in high-energy nuclear collisions. Here, we focus on a
+formal discussion of the limiting behaviour with increasing radiation
+frequency. In an absorptive (and polarizable) medium, this is determined by the
+behaviour of the exponential damping factor entering the spectrum and the
+formation time of radiation.",1201.1890v1
+2012-01-10,Nonequilibrium Damping of Collective Motion of Homogeneous Cold Fermi Condensates with Feshbach Resonances,"Collisionless damping of a condensate of cold Fermi atoms, whose scattering
+is controlled by a Feshbach resonance, is explored throughout the BCS and BEC
+regimes when small perturbations on its phase and amplitude modes are turned on
+to drive the system slightly out of equilibrium. Using a one-loop effective
+action, we first recreate the known result that for a broad resonance the
+amplitude of the condensate decays as $t^{-1/2}$ at late times in the BCS
+regime whereas it decays as $t^{-3/2}$ in the BEC regime. We then examine the
+case of an idealized narrow resonance, and find that this collective mode
+decays as $t^{-3/2}$ throughout both the BCS and BEC regimes. Although this
+seems to contradict earlier results that damping is identical for both broad
+and narrow resonances, the breakdown of the narrow resonance limit restores
+this universal behaviour. More measureably, the phase perturbation may give a
+shift on the saturated value to which the collective amplitude mode decays,
+which vanishes only in the deep BCS regime when the phase and amplitude modes
+are decoupled.",1201.2019v1
+2012-01-30,Modeling electricity spot prices using mean-reverting multifractal processes,"We discuss stochastic modeling of volatility persistence and
+anti-correlations in electricity spot prices, and for this purpose we present
+two mean-reverting versions of the multifractal random walk (MRW). In the first
+model the anti-correlations are modeled in the same way as in an
+Ornstein-Uhlenbeck process, i.e. via a drift (damping) term, and in the second
+model the anti-correlations are included by letting the innovations in the MRW
+model be fractional Gaussian noise with H < 1/2. For both models we present
+approximate maximum likelihood methods, and we apply these methods to estimate
+the parameters for the spot prices in the Nordic electricity market. The
+maximum likelihood estimates show that electricity spot prices are
+characterized by scaling exponents that are significantly different from the
+corresponding exponents in stock markets, confirming the exceptional nature of
+the electricity market. In order to compare the damped MRW model with the
+fractional MRW model we use ensemble simulations and wavelet-based variograms,
+and we observe that certain features of the spot prices are better described by
+the damped MRW model. The characteristic correlation time is estimated to
+approximately half a year.",1201.6137v1
+2012-05-06,Fractional wave equation and damped waves,"In this paper, a fractional generalization of the wave equation that
+describes propagation of damped waves is considered. In contrast to the
+fractional diffusion-wave equation, the fractional wave equation contains
+fractional derivatives of the same order $\alpha,\ 1\le \alpha \le 2$ both in
+space and in time. We show that this feature is a decisive factor for
+inheriting some crucial characteristics of the wave equation like a constant
+propagation velocity of both the maximum of its fundamental solution and its
+gravity and mass centers. Moreover, the first, the second, and the Smith
+centrovelocities of the damped waves described by the fractional wave equation
+are constant and depend just on the equation order $\alpha$. The fundamental
+solution of the fractional wave equation is determined and shown to be a
+spatial probability density function evolving in time that possesses finite
+moments up to the order $\alpha$. To illustrate analytical findings, results of
+numerical calculations and numerous plots are presented.",1205.1199v2
+2012-06-11,Testing the 130 GeV gamma-ray line with high energy resolution detectors,"Recently some hints of the existence of $\gamma$-ray line around 130 GeV are
+reported according to the analysis of Fermi-LAT data. If confirmed it would be
+the first direct evidence to show the existence of new physics beyond the
+standard model. Here we suggest that using the forthcoming high energy
+resolution $\gamma$-ray detectors, such as CALET and DAMPE, we may test whether
+it is real line structure or just the background effect. For DAMPE like
+detector with designed energy resolution $\sim1.5%$, a line significance will
+reach $11\sigma$ for the same statistics as Fermi-LAT. For about 1.4 yr survey
+observation, DAMPE may detect a $5\sigma$ signal of such a $\gamma$-ray line.",1206.2241v2
+2012-06-14,Finite-temperature dynamics of matter-wave dark solitons in linear and periodic potentials: an example of an anti-damped Josephson junction,"We study matter-wave dark solitons in atomic Bose-Einstein condensates at
+finite temperatures, under the effect of linear and periodic potentials. Our
+model, namely a dissipative Gross-Pitaevskii equation, is treated analytically
+by means of dark soliton perturbation theory, which results in a Newtonian
+equation of motion for the dark soliton center. This reduced model, which
+incorporates an effective washboard potential and an anti-damping term,
+constitutes an example of an anti-damped Josephson junction. We present a
+qualitative (local and global) analysis of the equation of motion. For
+sufficiently small wavenumbers of the periodic potential and weak linear
+potentials, the results are found to be in good agreement with pertinent ones
+obtained via a Bogoliubov-de Gennes analysis and direct numerical simulations.",1206.2993v1
+2012-06-15,Damping of giant dipole resonance in hot rotating nuclei,"The phonon damping model (PDM) is extended to include the effect of angular
+momentum at finite temperature. The model is applied to the study of damping of
+giant dipole resonance (GDR) in hot and noncollectively rotating spherical
+nuclei. The numerical results obtained for Mo88 and Sn106 show that the GDR
+width increases with both temperature T and angular momentum M. At T > 4 MeV
+and M<= 60 hbar the increase in the GDR width slows down for Sn106, whereas at
+M<= 80 hbar the GDR widths in both nuclei nearly saturate. By adopting the
+nuclear shear viscosity extracted from fission data at T= 0, it is shown that
+the maximal value of the angular momentum for Mo88 and Sn106 should be around
+46 and 55 hbar, respectively, so that the universal conjecture for the lower
+bound of the specific shear viscosity for all fluids is not violated up to T= 5
+MeV.",1206.3361v1
+2012-06-18,Sampled-data design for robust control of a single qubit,"This paper presents a sampled-data approach for the robust control of a
+single qubit (quantum bit). The required robustness is defined using a sliding
+mode domain and the control law is designed offline and then utilized online
+with a single qubit having bounded uncertainties. Two classes of uncertainties
+are considered involving the system Hamiltonian and the coupling strength of
+the system-environment interaction. Four cases are analyzed in detail including
+without decoherence, with amplitude damping decoherence, phase damping
+decoherence and depolarizing decoherence. Sampling periods are specifically
+designed for these cases to guarantee the required robustness. Two sufficient
+conditions are presented for guiding the design of unitary control for the
+cases without decoherence and with amplitude damping decoherence. The proposed
+approach has potential applications in quantum error-correction and in
+constructing robust quantum gates.",1206.3897v2
+2012-06-25,Trap anharmonicity and sloshing mode of a Fermi gas,"For a gas trapped in a harmonic potential, the sloshing (or Kohn) mode is
+undamped and its frequency coincides with the trap frequency, independently of
+the statistics, interaction and temperature of the gas. However, experimental
+trap potentials have usually Gaussian shape and anharmonicity effects appear as
+the temperature and, in the case of Fermions, the filling of the trap are
+increased. We study the sloshing mode of a degenerate Fermi gas in an
+anharmonic trap within the Boltzmann equation, including in-medium effects in
+both the transport and collision terms. The calculated frequency shifts and
+damping rates of the sloshing mode due to the trap anharmonicity are in
+satisfactory agreement with the available experimental data. We also discuss
+higher-order dipole, octupole, and bending modes and show that the damping of
+the sloshing mode is caused by its coupling to these modes.",1206.5688v2
+2012-09-06,Radiative energy loss in the absorptive QGP: taming the long formation lengths in coherent emission,"In an absorptive plasma, damping of radiation mechanisms can influence the
+bremsstrahlung formation in case of large radiation formation lengths. We study
+qualitatively the influence of this effect on the gluon bremsstrahlung spectrum
+off heavy quarks in the quark-gluon plasma. Independent of the heavy-quark
+mass, the spectrum is found to be strongly suppressed in an intermediate gluon
+energy region which grows with increasing gluon damping rate and increasing
+energy of the heavy quark. Thus, just as polarization effects in the plasma
+render the bremsstrahlung spectra independent of the quark mass in the soft
+gluon regime, damping effects tend to have a similar impact for larger gluon
+energies.",1209.1149v1
+2012-09-17,Power spectra in the eikonal approximation with adiabatic and non-adiabatic modes,"We use the so-called eikonal approximation, recently introduced in the
+context of cosmological perturbation theory, to compute power spectra for
+multi-component fluids. We demonstrate that, at any given order in standard
+perturbation theory, multipoint power spectra do not depend on the large-scale
+adiabatic modes. Moreover, we employ perturbation theories to decipher how
+nonadiabatic modes, such as a relative velocity between two different
+components, damp the small-scale matter power spectrum, a mechanism recently
+described in the literature. In particular, we do an explicit calculation at
+1-loop order of this effect. While the 1-loop result eventually breaks down, we
+show how the damping effect can be fully captured by the help of the eikonal
+approximation. A relative velocity not only induces mode damping but also
+creates large-scale anisotropic modulations of the matter power spectrum
+amplitude. We illustrate this for the Local Group environment.",1209.3662v2
+2012-09-26,Linear response theory for hydrodynamic and kinetic equations with long-range interactions,"We apply the linear response theory to systems with long-range interactions
+described by hydrodynamic equations such as the Euler, Smoluchowski, and damped
+Euler equations. We analytically determine the response of the system submitted
+to a pulse and to a step function. We compare these results with those obtained
+for collisionless systems described by the Vlasov equation. We show that, in
+the linear regime, the evolution of a collisionless system (Vlasov) with the
+waterbag distribution is the same as the evolution of a collision-dominated gas
+without dissipation (Euler). In this analogy, the maximum velocity of the
+waterbag distribution plays the role of the velocity of sound in the
+corresponding barotropic gas. When submitted to a step function, these systems
+exhibit permanent oscillations. Other distributions exhibit Landau damping and
+relax towards a steady state. We illustrate this behaviour with the Cauchy
+distribution which can be studied analytically. We apply our results to the HMF
+model and obtain a generalized Curie-Weiss law for the magnetic susceptibility.
+Finally, we compare the linear response theory to the initial value problem for
+the linearized Vlasov equation and report a case of algebraic damping of the
+initial perturbation.",1209.5987v1
+2012-09-15,Phase mixing of propagating Alfven waves in a stratified atmosphere: Solar spicules,"Alfvenic waves are thought to play an important role in coronal heating and
+solar wind acceleration. Recent observations by Hinode/SOT showed that the
+spicules mostly exhibit upward propagating high frequency waves. Here we
+investigate the dissipation of such waves due to phase mixing in stratified
+environment of solar spicules. Since they are highly dynamic structures with
+speeds at about significant fractions of the Alfven phase speed, we take into
+account the effects of steady flows. Our numerical simulations show that in the
+presence of stratification due to gravity, damping takes place in space than in
+time. The exponential damping low, exp(-At^3), is valid under spicule
+conditions, however the calculated damping time is much longer than the
+reported spicule lifetimes from observations.",1210.0485v1
+2012-10-11,Measurement of the damping of nuclear shell effect in the doubly magic $^{208}$Pb region,"The damping of the nuclear shell effect with excitation energy has been
+measured through an analysis of the neutron spectra following the triton
+transfer in the $^7$Li induced reaction on $^{205}$Tl. The measured neutron
+spectra demonstrate the expected large shell correction energy for the nuclei
+in the vicinity of doubly magic $^{208}$Pb and a small value for $^{184}$W. A
+quantitative extraction of the allowed values of the damping parameter
+$\gamma$, along with those for the asymptotic nuclear level density parameter
+$\tilde{a}$, has been made for the first time.",1210.3213v2
+2012-10-16,Optimal control of laser plasma instabilities using Spike Trains of Uneven Duration and Delay (STUD pulses) for ICF and IFE,"An adaptive method of controlling parametric instabilities in laser produced
+plasmas is proposed. It involves fast temporal modulation of a laser pulse on
+the fastest instability's amplification time scale, adapting to changing and
+unknown plasma conditions. These pulses are comprised of on and off sequences
+having at least one or two orders of magnitude contrast between them. Such
+laser illumination profiles are called STUD pulses for Spike Trains of Uneven
+Duration and Delay. The STUD pulse program includes scrambling the speckle
+patterns spatially in between the laser spikes. The off times allow damping of
+driven waves. The scrambling of the hot spots allows tens of damping times to
+elapse before hot spot locations experience recurring high intensity spikes.
+Damping in the meantime will have healed the scars of past growth. Another
+unique feature of STUD pulses on crossing beams is that their temporal profiles
+can be interlaced or staggered, and their interactions thus controlled with an
+on-off switch and a dimmer.",1210.4462v1
+2012-10-28,Mass Dependence of Instabilities of an Oscillator with Multiplicative and Additive Noise,"We study the instabilities of a harmonic oscillator subject to additive and
+dichotomous multiplicative noise, focussing on the dependance of the
+instability threshold on the mass. For multiplicative noise in the damping, the
+instability threshold is crossed as the mass is decreased, as long as the
+smaller damping is in fact negative. For multiplicative noise in the stiffness,
+the situation is more complicated and in fact the transition is reentrant for
+intermediate noise strength and damping. For multiplicative noise in the mass,
+the results depend on the implementation of the noise. One can take the
+velocity or the momentum to be conserved as the mass is changed. In these cases
+increasing the mass destabilizes the system. Alternatively, if the change in
+mass is caused by the accretion/loss of particles to the Brownian particle,
+these processes are asymmetric with momentum conserved upon accretion and
+velocity upon loss. In this case, there is no instability, as opposed to the
+other two implementations. We also study the distribution of the energy,
+finding a power-law cutoff at a value which increases with time.",1210.7433v1
+2012-10-30,Extending the Concept of Analog Butterworth Filter for Fractional Order Systems,"This paper proposes the design of Fractional Order (FO) Butterworth filter in
+complex w-plane (w=sq; q being any real number) considering the presence of
+under-damped, hyper-damped, ultra-damped poles. This is the first attempt to
+design such fractional Butterworth filters in complex w-plane instead of
+complex s-plane, as conventionally done for integer order filters. Firstly, the
+concept of fractional derivatives and w-plane stability of linear fractional
+order systems are discussed. Detailed mathematical formulation for the design
+of fractional Butterworth-like filter (FBWF) in w-plane is then presented.
+Simulation examples are given along with a practical example to design the FO
+Butterworth filter with given specifications in frequency domain to show the
+practicability of the proposed formulation.",1210.8194v3
+2012-11-24,Effects of Quantum Error Correction on Entanglement Sudden Death,"We investigate the effects of error correction on non-local quantum coherence
+as a function of time, extending the study by Sainz and Bj\""ork. We consider
+error correction of amplitude damping, pure phase damping and combinations of
+amplitude and phase damping as they affect both fidelity and quantum
+entanglement. Initial two-qubit entanglement is encoded in arbitrary real
+superpositions of both \Phi-type and \Psi-type Bell states. Our main focus is
+on the possibility of delay or prevention of ESD (early stage decoherence, or
+entanglement sudden death). We obtain the onset times for ESD as a function of
+the state-superposition mixing angle. Error correction affects entanglement and
+fidelity differently, and we exhibit initial entangled states for which error
+correction increases fidelity but decreases entanglement, and vice versa.",1211.5654v2
+2012-12-04,Polarization dependence of phonon influences in exciton-biexciton quantum dot systems,"We report on a strong dependence of the phonon-induced damping of Rabi
+dynamics in an optically driven exciton-biexciton quantum dot system on the
+polarization of the exciting pulse. While for a fixed pulse intensity the
+damping is maximal for linearly polarized excitation, it decreases with
+increasing ellipticity of the polarization. This finding is most remarkable
+considering that the carrier-phonon coupling is spin-independent. In addition
+to simulations based on a numerically exact real-time path integral approach,
+we present an analysis within a weak coupling theory that allows for analytical
+expressions for the pertinent damping rates. We demonstrate that an efficient
+coupling to the biexciton state is of central importance for the reported
+polarization dependencies. Further, we discuss influences of various system
+parameters and show that for finite biexciton binding energies Rabi scenarios
+differ qualitatively from the widely studied two-level dynamics.",1212.0642v1
+2012-12-10,Heat-induced damping modification in YIG/Pt hetero-structures,"We experimentally demonstrate the manipulation of magnetization relaxation
+utilizing a temperature difference across the thickness of an yttrium iron
+garnet/platinum (YIG/Pt) hetero-structure: the damping is either increased or
+decreased depending on the sign of the temperature gradient. This effect might
+be explained by a thermally-induced spin torque on the magnetization
+precession. The heat-induced variation of the damping is detected by microwave
+techniques as well as by a DC voltage caused by spin pumping into the adjacent
+Pt layer and the subsequent conversion into a charge current by the inverse
+spin Hall effect.",1212.2073v1
+2012-12-13,Surface plasmon polaritons in a semi-bounded degenerate plasma: role of spatial dispersion and collisions,"Surface plasmon polaritons (SPPs) in a semi-bounded degenerate plasma (e.g.,
+a metal) are studied using the quasiclassical mean-field kinetic model, taking
+into account the spatial dispersion of the plasma (due to quantum degeneracy of
+electrons) and electron-ion (electron-lattice, for metals) collisions. SPP
+dispersion and damping are obtained in both retarded ($\omega/k_z\sim c$) and
+non-retarded ($\omega/k_z\ll c$) regions, as well as in between. It is shown
+that the plasma spatial dispersion significantly affects the properties of
+SPPs, especially at short wavelengths (less than the collisionless skin depth,
+$\lambda\lesssim c/\omega_{pe}$). Namely, the collisionless (Landau) damping of
+SPPs (due to spatial dispersion) is comparable to the purely collisional
+(Ohmic) damping (due to electron-lattice collisions) in a wide range of SPP
+wavelengths, e.g., from $\lambda\sim20$ nm to $\lambda\sim0.8$ nm for SPP in
+gold at T=293 K, and from $\lambda\sim400$ nm to $\lambda\sim0.7$ nm for SPPs
+in gold at T=100 K. The spatial dispersion is also shown to affect, in a
+qualitative way, the dispersion of SPPs at short wavelengths $\lambda\lesssim
+c/\omega_{pe}$.",1212.3040v1
+2012-12-13,Branching of quasinormal modes for nearly extremal Kerr black holes,"We show that nearly extremal Kerr black holes have two distinct sets of
+quasinormal modes, which we call zero-damping modes (ZDMs) and damped modes
+(DMs). The ZDMs exist for all harmonic indices $l$ and $m \ge 0$, and their
+frequencies cluster onto the real axis in the extremal limit. The DMs have
+nonzero damping for all black hole spins; they exist for all counterrotating
+modes ($m<0$) and for corotating modes with $0\leq \mu\lesssim \mu_c=0.74$ (in
+the eikonal limit), where $\mu\equiv m/(l+1/2)$. When the two families coexist,
+ZDMs and DMs merge to form a single set of quasinormal modes as the black hole
+spin decreases. Using the effective potential for perturbations of the Kerr
+spacetime, we give intuitive explanations for the absence of DMs in certain
+areas of the spectrum and for the branching of the spectrum into ZDMs and DMs
+at large spins.",1212.3271v1
+2012-12-31,Effects of lateral device size and material properties on the ferromagnetic resonance response of spinwave eigen-modes in magnetic devices,"We analyze the effects of lateral device size and magnetic material
+parameters on the ferromagnetic resonance (FMR) response. Results presented are
+directly relevant to widely used FMR experimental techniques for extracting
+magnetic parameters from thin films, the results of which are often assumed to
+carry over to corresponding nanometer-sized patterned devices. We show that
+there can be significant variation in the FMR response with device size, and
+that the extent of the variation depends on the magnetic material properties.
+This explains, for example, why different experiments along these lines have
+yielded different size-dependent trends from damping measurements. Observed
+trends with increasing size and different material parameters are explained
+through the evolution of three distinct eigen-modes, demonstrating the
+respective roles of demagnetization and exchange. It is also shown that there
+is a crossover of dominant eigen-modes in the response signal, accompanied by
+conjugating edge-type modes, leading to evident effects in measured linewidth
+and damping. Among the sizes considered, in higher saturation magnetization, we
+observe as much as a 40% increase in apparent damping, due solely to device
+size variation.",1212.6835v1
+2013-01-16,Gain-tunable optomechanical cooling in a laser cavity,"We study the optical cooling of the resonator mirror in a
+cavity-optomechanical system that contains an optical gain medium. We find that
+the optical damping rate is vanishingly small for an incoherently pumped laser
+above threshold. In the presence of an external coherent drive however, the
+optical damping rate can be enhanced substantially with respect to that of a
+passive cavity. We show that the strength of the incoherent pump provides a
+conduit to tune the damping rate and the minimum attainable phonon number with
+the same radiation pressure force, and the latter can be lowered from that of a
+passive cavity if the thermal contribution is nonnegligible. We also show that
+the system can undergo a transition from the weak optomechanical coupling
+regime to the strong optomechanical coupling regime as the incoherent pump
+strength is varied.",1301.3762v2
+2013-01-18,Adiabatic stability under semi-strong interactions: The weakly damped regime,"We rigorously derive multi-pulse interaction laws for the semi-strong
+interactions in a family of singularly-perturbed and weakly-damped
+reaction-diffusion systems in one space dimension. Most significantly, we show
+the existence of a manifold of quasi-steady N-pulse solutions and identify a
+""normal-hyperbolicity"" condition which balances the asymptotic weakness of the
+linear damping against the algebraic evolution rate of the multi-pulses. Our
+main result is the adiabatic stability of the manifolds subject to this normal
+hyperbolicity condition. More specifically, the spectrum of the linearization
+about a fixed N-pulse configuration contains essential spectrum that is
+asymptotically close to the origin as well as semi-strong eigenvalues which
+move at leading order as the pulse positions evolve. We characterize the
+semi-strong eigenvalues in terms of the spectrum of an explicit N by N matrix,
+and rigorously bound the error between the N-pulse manifold and the evolution
+of the full system, in a polynomially weighted space, so long as the
+semi-strong spectrum remains strictly in the left-half complex plane, and the
+essential spectrum is not too close to the origin.",1301.4466v1
+2013-01-24,Spin transport parameters in metallic multilayers determined by ferromagnetic resonance measurements of spin pumping,"We measured spin transport in nonferromagnetic (NM) metallic multilayers from
+the contribution to damping due to spin pumping from a ferromagnetic Co90Fe10
+thin film. The multilayer stack consisted of NM1/NM2/Co90Fe10(2 nm)/NM2/NM3
+with varying NM materials and thicknesses. Using conventional theory for one
+dimensional diffusive spin transport in metals, we show that the effective
+damping due to spin pumping can be strongly affected by the spin transport
+properties of each NM in the multilayer, which permits the use of damping
+measurements to accurately determine the spin transport properties of the
+various NM layers in the full five-layer stack. We find that due to its high
+electrical resistivity, amorphous Ta is a poor spin conductor, in spite of a
+short spin-diffusion length of 1.0 nm, and that Pt is an excellent spin
+conductor by virtue of its low electrical resistivity and a spin diffusion
+length of only 0.5 nm. Spin Hall effect measurements may have underestimated
+the spin Hall angle in Pt by assuming a much longer spin diffusion length.",1301.5861v1
+2013-02-11,Low-damping epsilon-near-zero slabs: nonlinear and nonlocal optical properties,"We investigate second harmonic generation, low-threshold multistability,
+all-optical switching, and inherently nonlocal effects due to the free-electron
+gas pressure in an epsilon-near-zero (ENZ) metamaterial slab made of
+cylindrical, plasmonic nanoshells illuminated by TM-polarized light. Damping
+compensation in the ENZ frequency region, achieved by using gain medium inside
+the shells' dielectric cores, enhances the nonlinear properties. Reflection is
+inhibited and the electric field component normal to the slab interface is
+enhanced near the effective pseudo-Brewster angle, where the effective
+\epsilon-near-zero condition triggers a non-resonant, impedance-matching
+phenomenon. We show that the slab displays a strong effective, spatial
+nonlocality associated with leaky modes that are mediated by the compensation
+of damping. The presence of these leaky modes then induces further spectral and
+angular conditions where the local fields are enhanced, thus opening new
+windows of opportunity for the enhancement of nonlinear optical processes.",1302.2392v1
+2013-02-14,A Matlab toolbox for fractional relaxation-oscillation equations,"Stress relaxation and oscillation damping of complex viscoelastic media often
+manifest history- and path-dependent physical behaviors and cannot accurately
+be described by the classical models. Recent research found that fractional
+derivative models can characterize such complex relaxation and damping.
+However, to our best knowledge, easy-to-use numerical software is not available
+for fractional relaxation-oscillation (FRO) equations. This paper is to
+introduce an open source free Matlab toolbox which we developed in recent years
+for numerical solution of the FRO equations. This FRO toolbox uses the
+predictor-corrector approach for the discretization of time fractional
+derivative, and non-expert users can accurately solve fractional
+relaxation-oscillation equations via a friendly graphical user interface.
+Compared with experimental data, our numerical experiments show that the FRO
+toolbox is highly efficient and accurate to simulate viscoelastic stress
+relaxation and damped vibration. This free toolbox will help promote the
+research and practical use of fractional relaxation-oscillation equations.",1302.3384v1
+2013-03-11,The Analysis of Long-Term Frequency and Damping Wandering in Buildings Using the Random Decrement Technique,"The characterization and monitoring of buildings is an issue that has
+attracted the interest of many sectors over the last two decades. With the
+increasing use of permanent, continuous and real-time networks, ambient
+vibrations can provide a simple tool for the identification of dynamic building
+parameters. This study is focused on the long-term variation of frequency and
+damping in several buildings, using the Random Decrement Technique (RDT). RDT
+provides a fast, robust and accurate long-term analysis and improves the
+reliability of frequency and damping measurements for structural health
+monitoring. This reveals particularly useful information in finding out
+precisely how far changes in modal parameters can be related to changes in
+physical properties. This paper highlights the reversible changes of the
+structure's dynamic parameters, correlated with external forces, such as
+temperature and exposure to the sun. Contrasting behaviors are observed,
+including correlation and anti-correlation with temperature variations.",1303.2642v1
+2013-03-21,Optimizing atomic resolution of force microscopy in ambient conditions,"Ambient operation poses a challenge to AFM because in contrast to operation
+in vacuum or liquid environments, the cantilever dynamics change dramatically
+from oscillating in air to oscillating in a hydration layer when probing the
+sample. We demonstrate atomic resolution by imaging of the KBr(001) surface in
+ambient conditions by frequency-modulation atomic force microscopy with a
+cantilever based on a quartz tuning fork (qPlus sensor) and analyze both long-
+and short-range contributions to the damping. The thickness of the hydration
+layer increases with relative humidity, thus varying humidity enables us to
+study the in uence of the hydration layer thickness on cantilever damping.
+Starting with measurements of damping versus amplitude, we analyzed the signal
+and the noise characteristics at the atomic scale. We then determined the
+optimal amplitude which enabled us to acquire high-quality atomically resolved
+images.",1303.5204v2
+2013-04-10,Current Sheets and Collisionless Damping in Kinetic Plasma Turbulence,"We present the first study of the formation and dissipation of current sheets
+at electron scales in a wave-driven, weakly collisional, 3D kinetic turbulence
+simulation. We investigate the relative importance of dissipation associated
+with collisionless damping via resonant wave-particle interactions versus
+dissipation in small-scale current sheets in weakly collisional plasma
+turbulence. Current sheets form self-consistently from the wave-driven
+turbulence, and their filling fraction is well correlated to the electron
+heating rate. However, the weakly collisional nature of the simulation
+necessarily implies that the current sheets are not significantly dissipated
+via Ohmic dissipation. Rather, collisionless damping via the Landau resonance
+with the electrons is sufficient to account for the measured heating as a
+function of scale in the simulation, without the need for significant Ohmic
+dissipation. This finding suggests the possibility that the dissipation of the
+current sheets is governed by resonant wave-particle interactions and that the
+locations of current sheets correspond spatially to regions of enhanced
+heating.",1304.2958v2
+2013-04-22,Constant residual electrostatic electron plasma mode in Vlasov-Ampere system,"In a collisionless Vlasov-Poisson (V-P) electron plasma system, two types of
+modes for electric field perturbation exist: the exponentially Landau damped
+electron plasma waves and the initial-value sensitive ballistic modes. Here,
+the V-P system is modified slightly to a Vlasov-Ampere (V-A) system. A new
+constant residual mode is revealed. Mathematically, this mode comes from the
+Laplace transform of an initial electric field perturbation, and physically
+represents that an initial perturbation (e.g., external electric field
+perturbation) would not be damped away. Thus, this residual mode is more
+difficult to be damped than the ballistic mode. [Physics of Plasmas 20, 112108
+(2013); doi: 10.1063/1.4831761]",1304.5883v2
+2013-04-23,Existence and non-existence of breather solutions in damped and driven nonlinear lattices,"We investigate the existence of spatially localised solutions, in the form of
+discrete breathers, in general damped and driven nonlinear lattice systems of
+coupled oscillators. Conditions for the exponential decay of the difference
+between the maximal and minimal amplitudes of the oscillators are provided
+which proves that initial non-uniform spatial patterns representing breathers
+attain exponentially fast a spatially uniform state preventing the formation
+and/or preservation of any breather solution at all. Strikingly our results are
+generic in the sense that they hold for arbitrary dimension of the system, any
+attractive interaction, coupling strength and on-site potential and general
+driving fields. Furthermore, our rigorous quantitative results establish
+conditions under which discrete breathers in general damped and driven
+nonlinear lattices can exist at all and open the way for further research on
+the emergent dynamical scenarios, in particular features of pattern formation,
+localisation and synchronisation, in coupled cell networks.",1304.6370v3
+2013-06-21,Inviscid damping and the asymptotic stability of planar shear flows in the 2D Euler equations,"We prove asymptotic stability of shear flows close to the planar Couette flow
+in the 2D inviscid Euler equations on $\Torus \times \Real$. That is, given an
+initial perturbation of the Couette flow small in a suitable regularity class,
+specifically Gevrey space of class smaller than 2, the velocity converges
+strongly in L^2 to a shear flow which is also close to the Couette flow. The
+vorticity is asymptotically driven to small scales by a linear evolution and
+weakly converges as $t \rightarrow \pm\infty$. The strong convergence of the
+velocity field is sometimes referred to as inviscid damping, due to the
+relationship with Landau damping in the Vlasov equations. This convergence was
+formally derived at the linear level by Kelvin in 1887 and it occurs at an
+algebraic rate first computed by Orr in 1907; our work appears to be the first
+rigorous confirmation of this behavior on the nonlinear level.",1306.5028v3
+2013-07-12,Spin injection from topological insulator tunnel-coupled to metallic leads,"We study theoretically helical edge states of 2D and 3D topological
+insulators (TI) tunnel-coupled to metal leads and show that their transport
+properties are strongly affected by contacts as the latter play a role of a
+heat bath and induce damping and relaxation of electrons in the helical states
+of TI. A simple structure that produces a pure spin current in the external
+circuit is proposed. The current and spin current delivered to the external
+circuit depend on relation between characteristic lengths: damping length due
+to tunneling, contact length and, in case of 3D TI, mean free path and spin
+relaxation length caused by momentum scattering. If the damping length due to
+tunneling is the smallest one, then the electric and spin currents are
+proportional to the conductance quantum in 2D TI, and to the conductance
+quantum multiplied by the ratio of the contact width to the Fermi wavelength in
+3D TI.",1307.3333v1
+2013-07-19,Damping and non-linearity of a levitating magnet in rotation above a superconductor,"We study the dissipation of moving magnets in levitation above a
+superconductor. The rotation motion is analyzed using optical tracking
+techniques. It displays a remarkable regularity together with long damping time
+up to several hours. The magnetic contribution to the damping is investigated
+in detail by comparing 14 distinct magnetic configurations, and points towards
+amplitude-dependent dissipation mechanisms. The non-linear dynamics of the
+mechanical rotation motion is also revealed and described with an effective
+Duffing model. The obtained picture of the coupling of levitating magnets to
+their environment sheds light on their potential as ultra-low dissipation
+mechanical oscillators for high precision physics.",1307.5155v1
+2013-07-19,Perfect squeezing by damping modulation in circuit quantum electrodynamics,"Dissipation-driven quantum state engineering uses the environment to steer
+the state of quantum systems and preserve quantum coherence in the steady
+state. We show that modulating the damping rate of a microwave resonator
+generates a vacuum squeezed state of arbitrary squeezing strength, thereby
+constituting a mechanism allowing perfect squeezing. Given the recent
+experimental realizations in circuit QED of a microwave resonator with a
+tunable damping rate [Yin et al., Phys. Rev. Lett. 110, 107001 (2013)],
+superconducting circuits are an ideal playground to implement this technique.
+By dispersively coupling a qubit to the microwave resonator, it is possible to
+obtain qubit-state dependent squeezing.",1307.5311v2
+2013-07-27,"Charge-carrier-induced frequency renormalization, damping and heating of vibrational modes in nanoscale junctions","In nanoscale junctions the interaction between charge carriers and the local
+vibrations results in renormalization, damping and heating of the vibrational
+modes. We here formulate a nonequilibrium Green's functions based theory to
+describe such effects. Studying a generic junction model with an off-resonant
+electronic level, we find a strong bias dependence of the frequency
+renormalization and vibrational damping accompanied by pronounced nonlinear
+vibrational heating in junctions with intermediate values of the coupling to
+the leads. Combining our theory with ab-initio calculations we furthermore show
+that the bias dependence of the Raman shifts and linewidths observed
+experimentally in an OPV3 junction [D. Ward et al., Nature Nano. 6, 33 (2011)]
+may be explained by a combination of dynamic carrier screening and molecular
+charging.",1307.7288v3
+2013-07-30,Phase retrapping in a pointlike $\varphi$ Josephson junction: the Butterfly effect,"We consider a $\varphi$ Josephson junction, which has a bistable zero-voltage
+state with the stationary phases $\psi=\pm\varphi$. In the non-zero voltage
+state the phase ""moves"" viscously along a tilted periodic double-well
+potential. When the tilting is reduced quasistatically, the phase is retrapped
+in one of the potential wells. We study the viscous phase dynamics to determine
+in which well ($-\varphi$ or $+\varphi$) the phase is retrapped for a given
+damping, when the junction returns from the finite-voltage state back to
+zero-voltage state. In the limit of low damping the $\varphi$ Josephson
+junction exhibits a butterfly effect --- extreme sensitivity of the destination
+well on damping. This leads to an impossibility to predict the destination
+well.",1307.8042v1
+2013-08-10,CESR Test Accelerator,"The Cornell Electron Storage Ring (CESR) was reconfigured in 2008 as a test
+accelerator to investigate the physics of ultra-low emittance damping rings.
+During the approximately 40 days/year available for dedicated operation as a
+test accelerator, specialized instrumentation is used to measure growth and
+mitigation of the electron cloud, emittance growth due to electron cloud,
+intra-beam scattering, and ions, and single and multi-bunch instabilities
+generated by collective effects. The flexibility of the CESR guide field optics
+and the integration of accelerator modeling codes with the control system have
+made possible an extraordinary range of experiments. Findings at CesrTA with
+respect to electron cloud effects, emittance tuning techniques, and beam
+instrumentation for measuring electron cloud, beam sizes, and beam positions
+are the basis for much of the design of the ILC damping rings as documented in
+the ILC-Technical Design Report. The program has allowed the Cornell group to
+cultivate the kind of talent and expertise that will be absolutely essential to
+the final engineering design, and commissioning of the damping rings for a
+linear collider.",1308.2325v1
+2013-09-09,Characterization of the International Linear Collider damping ring optics,"A method is presented for characterizing the emittance dilution and dynamic
+aperture for an arbitrary closed lattice that includes guide field magnet
+errors, multipole errors and misalignments. This method, developed and tested
+at the Cornell Electron Storage Ring Test Accelerator (CesrTA), has been
+applied to the damping ring lattice for the International Linear Collider
+(ILC). The effectiveness of beam based emittance tuning is limited by beam
+position monitor (BPM) measurement errors, number of corrector magnets and
+their placement, and correction algorithm. The specifications for damping ring
+magnet alignment, multipole errors, number of BPMs, and precision in BPM
+measurements are shown to be consistent with the required emittances and
+dynamic aperture. The methodology is then used to determine the minimum number
+of position monitors that is required to achieve the emittance targets, and how
+that minimum depends on the location of the BPMs. Similarly, the maximum
+tolerable multipole errors are evaluated. Finally, the robustness of each BPM
+configuration with respect to random failures is explored.",1309.2248v3
+2013-10-13,What the Timing of Millisecond Pulsars Can Teach us about Their Interior,"The cores of compact stars reach the highest densities in nature and
+therefore could consist of novel phases of matter. We demonstrate via a
+detailed analysis of pulsar evolution that precise pulsar timing data can
+constrain the star's composition, through unstable global oscillations
+(r-modes) whose damping is determined by microscopic properties of the
+interior. If not efficiently damped, these modes emit gravitational waves that
+quickly spin down a millisecond pulsar. As a first application of this general
+method, we find that ungapped interacting quark matter is consistent with both
+the observed radio and x-ray data, whereas for ordinary nuclear matter some
+additional enhanced damping mechanism is required.",1310.3524v2
+2013-11-28,Conservative effects in spin-transfer-driven magnetization dynamics,"It is shown that under appropriate conditions spin-transfer-driven
+magnetization dynamics in a single-domain nanomagnet is conservative in nature
+and admits a specific integral of motion, which is reduced to the usual
+magnetic energy when the spin current goes to zero. The existence of this
+conservation law is connected to the symmetry properties of the dynamics under
+simultaneous inversion of magnetisation and time. When one applies an external
+magnetic field parallel to the spin polarization, the dynamics is transformed
+from conservative into dissipative. More precisely, it is demonstrated that
+there exists a state function such that the field induces a monotone relaxation
+of this function toward its minima or maxima, depending on the field
+orientation. These results hold in the absence of intrinsic damping effects.
+When intrinsic damping is included in the description, a competition arises
+between field-induced and damping-induced relaxations, which leads to the
+appearance of limit cycles, that is, of magnetization self-oscillations.",1311.7344v1
+2013-12-05,The initial condition problems of damped quantum harmonic oscillator,"We investigate the exact dynamics of the damped quantum harmonic oscillator
+under the (un)correlated initial conditions. The master equation is generalized
+to the cases of the arbitrary factorized state and/or Gaussian state. We show
+that the variances of the factorized Gaussian state do not sensitively depend
+on the initial oscillator-bath correlation, which however can remarkably affect
+the mean values even at high temperature. We also illustrate that the
+correlations among the factorized states still give rise to the initial dips
+during the purity evolutions, which can be smoothed out by increasing the
+amount of correlation to some extent. We finally study the effects of repeated
+measurements on the time evolution of the damped oscillator analytically, which
+are compared with the weak coupling results to indicate that they give rather
+different transient behaviors even for an intermediate coupling.",1312.1454v1
+2013-12-13,Optical variability of quasars: a damped random walk,"A damped random walk is a stochastic process, defined by an exponential
+covariance matrix that behaves as a random walk for short time scales and
+asymptotically achieves a finite variability amplitude at long time scales.
+Over the last few years, it has been demonstrated, mostly but not exclusively
+using SDSS data, that a damped random walk model provides a satisfactory
+statistical description of observed quasar variability in the optical
+wavelength range, for rest-frame timescales from 5 days to 2000 days. The
+best-fit characteristic timescale and asymptotic variability amplitude scale
+with the luminosity, black hole mass, and rest wavelength, and appear
+independent of redshift. In addition to providing insights into the physics of
+quasar variability, the best-fit model parameters can be used to efficiently
+separate quasars from stars in imaging surveys with adequate long-term
+multi-epoch data, such as expected from LSST.",1312.3966v1
+2013-12-25,Non-linear damping of visco-resistive Alfven waves in solar spicules,"Interaction of Alfven waves with plasma inhomogeneities generates phase
+mixing which can lead to dissipate Alfven waves and to heat the solar plasma.
+Here we study the dissipation of Alfven waves by phase mixing due to viscosity
+and resistivity variations with height. We also consider nonlinear
+magnetohydrodynamic (MHD) equations in our theoretical model. Non-linear terms
+of MHD equations include perturbed velocity, magnetic field, and density. To
+investigate the damping of Alfven waves in a stratified atmosphere of solar
+spicules, we solve the non-linear MHD equations in the x-z plane. Our
+simulations show that the damping is enhanced due to viscosity and resistivity
+gradients. Moreover, energy variations is influenced due to nonlinear terms in
+MHD equations.",1312.7866v1
+2013-12-31,A novel variability-based method for quasar selection: evidence for a rest frame ~54 day characteristic timescale,"We compare quasar selection techniques based on their optical variability
+using data from the Catalina Real-time Transient Survey (CRTS). We introduce a
+new technique based on Slepian wavelet variance (SWV) that shows comparable or
+better performance to structure functions and damped random walk models but
+with fewer assumptions. Combining these methods with WISE mid-IR colors
+produces a highly efficient quasar selection technique which we have validated
+spectroscopically. The SWV technique also identifies characteristic timescales
+in a time series and we find a characteristic rest frame timescale of ~54 days,
+confirmed in the light curves of ~18000 quasars from CRTS, SDSS and MACHO data,
+and anticorrelated with absolute magnitude. This indicates a transition between
+a damped random walk and $P(f) \propto f^{-1/3}$ behaviours and is the first
+strong indication that a damped random walk model may be too simplistic to
+describe optical quasar variability.",1401.1785v1
+2014-02-09,Manipulation of tripartite-to-bipartite entanglement localization under quantum noises and its application to entanglement distribution,"This paper is to investigate the effects of quantum noises on entanglement
+localization by taking an example of reducing a three-qubit
+Greenberger-Horne-Zeilinger (GHZ) state to a two-qubit entangled state. We
+consider, respectively, two types of quantum decoherence, i.e.,
+amplitude-damping and depolarizing decoherence, and explore the best von
+Neumann measurements on one of three qubits of the triple GHZ state for making
+the amount of entanglement of the collapsed bipartite state be as large as
+possible. The results indicate that different noises have different impacts on
+entanglement localization, and that the optimal strategy for reducing a
+three-qubit GHZ state to a two-qubit one via local measurements and classical
+communications in the amplitude-damping case is different from that in the
+noise-free case. We also show that the idea of entanglement localization could
+be utilized to improve the quality of bipartite entanglement distributing
+through amplitude-damping channels. These findings might shed a new light on
+entanglement manipulations and transformations.",1402.1914v2
+2014-02-25,Thermodynamic anomalies in the presence of dissipation: from the free particle to the harmonic oscillator,"A free particle coupled to a heat bath can exhibit a number of thermodynamic
+anomalies like a negative specific heat or reentrant classicality. These
+low-temperature phenomena are expected to be modified at very low temperatures
+where finite-size effects associated with the discreteness of the energy
+spectrum become relevant. In this paper, we explore in which form the
+thermodynamic anomalies of the free damped particle appear for a damped
+harmonic oscillator. Since the discreteness of the oscillator's energy spectrum
+is fully accounted for, the results are valid for arbitrary temperatures. As
+expected, they are in agreement with the third law of thermodynamics and
+indicate how the thermodynamic anomalies of the free damped particle can be
+reconciled with the third law. Particular attention is paid to the transition
+from the harmonic oscillator to the free particle when the limit of the
+oscillator frequency to zero is taken.",1402.6221v1
+2014-02-26,Magneto-elastic modes and lifetime of magnons in thin yttrium-iron garnet films,"We calculate the effects of the spin-lattice coupling on the magnon spectrum
+of thin ferromagnetic films consisting of the magnetic insulator yttrium-iron
+garnet. The magnon-phonon hybridisation generates a characteristic minimum in
+the spin dynamic structure factor which quantitatively agrees with recent
+Brillouin light scattering experiments. We also show that at room temperature
+the phonon contribution to the magnon damping exhibits a rather complicated
+momentum dependence: In the exchange regime the magnon damping is dominated by
+Cherenkov type scattering processes, while in the long-wavelength dipolar
+regime these processes are subdominant and the magnon damping is two orders of
+magnitude smaller. We supplement our calculations by actual measurements of the
+magnon relaxation in the dipolar regime. Our theory provides a simple
+explanation of a recent experiment probing the different temperatures of the
+magnon and phonon gases in yttrium-iron garnet.",1402.6575v2
+2014-02-28,A new way to evaluate x-ray Brillouin scattering data,"Making use of the classical second moment sum rule, it is possible to convert
+a series of constant-Q x-ray Brillouin scattering scans (Q momentum transfer)
+into a series of constant frequency scans over the measured $Q$ range. The
+method is applied to literature results for the phonon dispersion in liquid
+vitreous silica and in glassy polybutadiene. It turns out that the constant
+frequency scans are again well fitted by the damped harmonic oscillator
+function, but now in terms of a Q-independent phonon damping depending
+exclusively on the frequency. At low frequency, the sound velocity and the
+damping of both evaluations agree, but at higher frequencies one gets
+significant differences. The results in silica suggest a new interpretation of
+x-ray Brillouin data in terms of a strong mixing of longitudinal and transverse
+phonons toward higher frequencies. The results in polybutadiene enlighten the
+crossover from Brillouin to Umklapp scattering.",1402.7237v1
+2014-03-10,Quantum Fisher Information of W States in Decoherence Channels,"We study the quantum Fisher information (QFI) of W states analytically with
+respect to SU(2) rotations in the basic decoherence channels i.e. depolarizing
+(DPC), amplitude damping (ADC) and phase damping (PDC), and present the
+interesting behavior of QFI of W states, especially when compared to that of
+GHZ states [Ma et al., Phys. Rev. A, 84, 022302 (2011)]. We find that when
+initially pure W states are under decoherence, i) DPC: as decoherence starts
+and increases, QFI smoothly decays; ii) ADC: just as decoherence starts, QFI
+exhibits a sudden drop to the shot noise level and as decoherence increases,
+QFI continues to decrease to zero and then increases back to the shot noise
+level; iii) PDC: just as decoherence starts, a sudden death of QFI occurs and
+QFI remains zero for any rate of decoherence, therefore W states in phase
+damping channel do not provide phase sensitivity. We also find that, on the
+contrary to GHZ states, pure or decohered W states are not sensitive with
+respect to rotations in z direction and the sensitivities with respect to
+rotations in x and y directions are equal to each other, implying no sudden
+change points of QFI due to competition between directions.",1403.2376v1
+2014-03-14,Silk damping at a redshift of a billion: a new limit on small-scale adiabatic perturbations,"We study the dissipation of small-scale adiabatic perturbations at early
+times when the Universe is hotter than T ~ 0.5 keV. When the wavelength falls
+below the damping scale 1/kD, the acoustic modes diffuse and thermalize,
+causing entropy production. Before neutrino decoupling, kD is primarily set by
+the neutrino shear viscosity, and we study the effect of acoustic damping on
+the relic neutrino number, primordial nucleosynthesis, dark-matter freeze-out,
+and baryogenesis. This sets a new limit on the amplitude of primordial
+fluctuations of DeltaR^2 < 0.007 at 10^4/Mpc< k < 10^5/Mpc and a model
+dependent limit of DeltaR^2 < 0.3 at k < 10^{20-25}/Mpc.",1403.3697v1
+2014-06-02,CMB $μ$ distortion from primordial gravitational waves,"We propose a new mechanism of generating the $\mu$ distortion in cosmic
+microwave background (CMB) originated from primordial gravitational waves. Such
+$\mu$ distortion is generated by the damping of the temperature anisotropies
+through the Thomson scattering, even on scales larger than that of Silk
+damping. This mechanism is in sharp contrast with that from the primordial
+curvature (scalar) perturbations, in which the temperature anisotropies mainly
+decay by Silk damping effects. We estimate the size of the $\mu$ distortion
+from the new mechanism, which can be used to constrain the amplitude of
+primordial gravitational waves on smaller scales independently from the CMB
+anisotropies, giving more wide-range constraint on their spectral index by
+combining the amplitude from the CMB anisotropies.",1406.0451v2
+2014-06-04,Self-organized escape processes of linear chains in nonlinear potentials,"An enhancement of localized nonlinear modes in coupled systems gives rise to
+a novel type of escape process. We study a spatially one dimensional set-up
+consisting of a linearly coupled oscillator chain of $N$ mass-points situated
+in a metastable nonlinear potential. The Hamilton-dynamics exhibits breather
+solutions as a result of modulational instability of the phonon states. These
+breathers localize energy by freezing other parts of the chain. Eventually this
+localised part of the chain grows in amplitude until it overcomes the critical
+elongation characterized by the transition state. Doing so, the breathers
+ignite an escape by pulling the remaining chain over the barrier. Even if the
+formation of singular breathers is insufficient for an escape, coalescence of
+moving breathers can result in the required concentration of energy. Compared
+to a chain system with linear damping and thermal fluctuations the breathers
+help the chain to overcome the barriers faster in the case of low damping. With
+larger damping, the decreasing life time of the breathers effectively inhibits
+the escape process.",1406.0938v1
+2014-06-08,Dissipation-driven squeezed and sub-Poissonian mechanical states in quadratic optomechanical systems,"In this work we study an optomechanical system in which there is a purely
+quadratic optomechanical coupling between the optical and mechanical modes. The
+optical mode is pumped by three coherent fields and the mechanical mode is
+parametrically driven. We show that if the frequencies and amplitudes of both
+optical and mechanical drivings are properly chosen, the optomechanical
+interaction gives rise to an effective interaction, which, in the presence of
+optical damping and in the absence of mechanical damping, has the squeezed
+vacuum state and the squeezed one phonon state as dark states of the dynamics.
+These states are well known for presenting quadrature squeezing and
+sub-Poissonian statistics. However, even in the presence of mechanical damping
+it is possible to find steady states with large degrees of quadrature squeezing
+or strong sub-Poissonian statistics. Furthermore, we find a counter-intuitive
+behavior in which a nonzero temperature of the mechanical environment allows
+the observation of mechanical states with more pronounced sub-Poissonian
+statistics.",1406.1987v3
+2014-06-13,Frequency-dependent damping in propagating slow magneto-acoustic waves,"Propagating slow magneto-acoustic waves are often observed in polar plumes
+and active region fan loops. The observed periodicities of these waves range
+from a few minutes to few tens of minutes and their amplitudes were found to
+decay rapidly as they travel along the supporting structure. Previously,
+thermal conduction, compressive viscosity, radiation, density stratification,
+and area divergence, were identified to be some of the causes for change in the
+slow wave amplitude. Our recent studies indicate that the observed damping in
+these waves is frequency dependent. We used imaging data from SDO/AIA, to study
+this dependence in detail and for the first time from observations we attempted
+to deduce a quantitative relation between damping length and frequency of these
+oscillations. We developed a new analysis method to obtain this relation. The
+observed frequency dependence does not seem to agree with the current linear
+wave theory and it was found that the waves observed in the polar regions show
+a different dependence from those observed in the on-disk loop structures
+despite the similarity in their properties.",1406.3565v1
+2014-06-24,On finite density effects on cosmic reheating and moduli decay and implications for Dark Matter production,"We study the damping of an oscillating scalar field in a
+Friedmann-Robertson-Walker spacetime by perturbative processes, taking into
+account the finite density effects that interactions with the plasma of decay
+products have on the damping rate. The scalar field may be identified with the
+inflaton, in which case this process leads to the reheating of the universe
+after inflation. It can also resemble a modulus that dominates the energy
+density of the universe at later times. We find that the finite density
+corrections to the damping rate can have a drastic effect on the thermal
+history and considerably increase both, the maximal temperature in the early
+universe and the reheating temperature at the onset of the radiation dominated
+era. As a result abundance of some Dark Matter candidates may be considerably
+larger than previously estimated. We give improved analytic estimates for the
+maximal and the reheating temperatures and confirm them numerically in a simple
+model.",1406.6243v2
+2014-08-13,Probing dense matter in compact star cores with radio pulsar data,"Astrophysical observations of compact stars provide, in addition to collider
+experiments, the other big source of information on matter under extreme
+conditions. The largest and most precise data set about neutron stars is the
+timing data of radio pulsars. We show how this unique data can be used to learn
+about the ultra-dense matter in the compact star interior. The method relies on
+astro-seismology based on special global oscillation modes (r-modes) that emit
+gravitational waves. They would prevent pulsars from spinning with their
+observed high frequencies, unless the damping of these modes, determined by the
+microscopic properties of matter, can prevent this. We show that for each form
+of matter there is a distinct region in a frequency/spindown-rate diagram where
+r-modes can be present. We find that stars containing ungapped quark matter are
+consistent with both the observed radio and x-ray data, whereas, even when
+taking into account the considerable uncertainties, neutron star models with
+standard viscous damping are inconsistent with both data sets and additional
+damping mechanisms would be required.",1408.3152v1
+2014-08-25,Spin-Scattering Rates in Metallic Thin Films Measured by Ferromagnetic Resonance Damping Enhanced by Spin-Pumping,"We determined the spin-transport properties of Pd and Pt thin films by
+measuring the increase in ferromagnetic resonance damping due to spin-pumping
+in ferromagnetic (FM)-nonferromagnetic metal (NM) multilayers with varying NM
+thicknesses. The increase in damping with NM thickness depends strongly on both
+the spin- and charge-transport properties of the NM, as modeled by diffusion
+equations that include both momentum- and spin-scattering parameters. We use
+the analytical solution to the spin-diffusion equations to obtain
+spin-diffusion lengths for Pt and Pd. By measuring the dependence of
+conductivity on NM thickness, we correlate the charge- and spin-transport
+parameters, and validate the applicability of various models for
+momentum-scattering and spin-scattering rates in these systems: constant,
+inverse-proportional (Dyakanov-Perel), and linear-proportional (Elliot-Yafet).
+We confirm previous reports that the spin-scattering time can be shorter than
+the momentum scattering time in Pt, and the Dyakanov-Perel-like model is the
+best fit to the data.",1408.5921v2
+2014-08-27,Quasi-particle Lifetime in a Mixture of Bose and Fermi Superfluids,"In this letter, to reveal the effect of quasi-particle interactions in a
+Bose-Fermi superfluid mixture, we consider the lifetime of quasi-particle of
+Bose superfluid due to its interaction with quasi-particles in Fermi
+superfluid. We find that this damping rate, i.e. inverse of the lifetime, has
+quite different threshold behavior at the BCS and the BEC side of the Fermi
+superfluid. The damping rate is a constant nearby the threshold momentum in the
+BCS side, while it increases rapidly in the BEC side. This is because in the
+BCS side the decay processe is restricted by constant density-of-state of
+fermion quasi-particle nearby Fermi surface, while such a restriction does not
+exist in the BEC side where the damping process is dominated by bosonic
+quasi-particles of Fermi superfluid. Our results are related to collective mode
+experiment in recently realized Bose-Fermi superfluid mixture.",1408.6419v1
+2014-09-04,A numerical study of the pull-in instability in some free boundary models for MEMS,"In this work we numerically compute the bifurcation curve of stationary
+solutions for the free boundary problem for MEMS in one space dimension. It has
+a single turning point, as in the case of the small aspect ratio limit. We also
+find a threshold for the existence of global-in-time solutions of the evolution
+equation given by either a heat or a damped wave equation. This threshold is
+what we term the dynamical pull-in value: it separates the stable operation
+regime from the touchdown regime. The numerical calculations show that the
+dynamical threshold values for the heat equation coincide with the static
+values. For the damped wave equation the dynamical threshold values are smaller
+than the static values. This result is in agreement with the observations
+reported for a mass-spring system studied in the engineering literature. In the
+case of the damped wave equation, we also show that the aspect ratio of the
+device is more important than the inertia in the determination of the pull-in
+value.",1409.1291v2
+2014-09-15,"Direct path from microscopic mechanics to Debye shielding, Landau damping, and wave-particle interaction","The derivation of Debye shielding and Landau damping from the $N$-body
+description of plasmas is performed directly by using Newton's second law for
+the $N$-body system. This is done in a few steps with elementary calculations
+using standard tools of calculus, and no probabilistic setting. Unexpectedly,
+Debye shielding is encountered together with Landau damping. This approach is
+shown to be justified in the one-dimensional case when the number of particles
+in a Debye sphere becomes large. The theory is extended to accommodate a
+correct description of trapping and chaos due to Langmuir waves. Shielding and
+collisional transport are found to be two related aspects of the repulsive
+deflections of electrons, in such a way that each particle is shielded by all
+other ones while keeping in uninterrupted motion.",1409.4323v1
+2014-09-19,Damping of metallized bilayer nanomechanical resonators at room temperature,"We investigate the influence of gold thin-films subsequently deposited on a
+set of initially bare, doubly clamped, high-stress silicon nitride string
+resonators at room temperature. Analytical expressions for resonance frequency,
+quality factor and damping for both in- and out-of-plane flexural modes of the
+bilayer system are derived, which allows for the determination of effective
+elastic parameters of the composite structure from our experimental data. We
+find the inverse quality factor to scale linearly with the gold film thickness,
+indicating that the overall damping is governed by losses in the metal.
+Correspondingly, the mechanical linewidth increases by more than one order of
+magnitude compared to the bare silicon nitride string resonator. Furthermore,
+we extract mechanical quality factors of the gold film for both flexural modes
+and show that they can be enhanced by complete deposition of the metal in a
+single step, suggesting that surface and interface losses play a vital role in
+metal thin-films.",1409.5670v1
+2014-10-09,Non-Fermi-liquid behavior and anomalous suppression of Landau damping in layered metals close to ferromagnetism,"We analyse the low-energy physics of nearly ferromagnetic metals in two
+spatial dimensions using the functional renormalization group technique. We
+find a new low-energy fixed point, at which the fermionic (electron-like)
+excitations are non-Fermi-liquid ($z_f = 13/10$) and the magnetic fluctuations
+exhibit an anomalous Landau damping whose rate vanishes as $\Gamma_{\bf q} \sim
+\vert {\bf q} \vert^{3/5}$ in the low-$\vert {\bf q} \vert$ limit. We discuss
+this renormalization of the Landau-damping exponent, which is the major novel
+prediction of our work, and highlight the possible link between that
+renormalization and neutron-scattering data on UGe$_2$ and related compounds.
+Implications of our analysis for YFe$_2$Al$_{10}$ are also discussed.",1410.2539v3
+2014-10-09,Special mean motion resonance pairs: Mimas-Tethys and Titan-Hyperion,"Five pairs of large solar system satellites occupy first order mean-motion
+resonances (MMRs). Among these, the pairs of Mimas-Tethys and Titan-Hyperion
+are special. They are located much deeper in resonance than the others and
+their critical arguments librate with much greater amplitudes. These
+characteristics are traced to the insignificant damping, over $\Gyr$
+timescales, of Mimas's orbital inclination and Hyperion's orbital eccentricity.
+Absent that, these resonances would not survive. Instead their librations would
+be overstable and escape from resonance would occur on the relevant damping
+time. Unlike the aforementioned MMRs, those involving Enceladus-Dione,
+Io-Europa, and Europa-Ganymede are limited by eccentricity damping. They must
+either remain at the shallow depths they currently occupy, or, if they venture
+deeper, retreat after a limited time. The latter seems almost certain for
+Enceladus-Dione and quite likely for the others, We examine the MMRs involving
+Mimas-Tethys and Titan-Hyperion under the assumption that they formed as a
+result of convergent migration. Capture probabilities are $\sim 6\%$ for the
+former and $100\%$ for the latter. The possibility of collisional excitation of
+their large librations is investigated but largely discounted.",1410.2648v1
+2014-11-13,Stability and bifurcation for the Kuramoto model,"We study the mean-field limit of the Kuramoto model of globally coupled
+oscillators. By studying the evolution in Fourier space and understanding the
+domain of dependence, we show a global stability result. Moreover, we can
+identify function norms to show damping of the order parameter for velocity
+distributions and perturbations in $\mathcal{W}^{n,1}$ for $n > 1$. Finally,
+for sufficiently regular velocity distributions we can identify exponential
+decay in the stable case and otherwise identify finitely many eigenmodes. For
+these eigenmodes we can show a center-unstable manifold reduction, which gives
+a rigorous tool to obtain the bifurcation behaviour. The damping is similar to
+Landau damping for the Vlasov equation.",1411.3752v3
+2014-11-26,A singular finite element technique for calculating continuum damping of Alfvén eigenmodes,"Damping due to continuum resonances can be calculated using dissipation-less
+ideal magnetohydrodynamics (MHD) provided that the poles due to these
+resonances are properly treated. We describe a singular finite element
+technique for calculating the continuum damping of Alfv\'{e}n waves. A
+Frobenius expansion is used to determine appropriate finite element basis
+functions on an inner region surrounding a pole due to the continuum resonance.
+The location of the pole due to the continuum resonance and mode frequency are
+calculated iteratively using a Galerkin method. This method is used to find the
+complex frequency and mode structure of a toroidicity-induced Alfv\'{e}n
+eigenmode (TAE) in a large aspect ratio circular tokamak and are shown to agree
+closely with a complex contour technique.",1411.7111v1
+2014-11-26,Energy decay for a locally undamped wave equation,"We study the decay rate for the energy of solutions of a damped wave equation
+in a situation where the Geometric Control Condition is violated. We assume
+that the set of undamped trajectories is a flat torus of positive codimension
+and that the metric is locally flat around this set. We further assume that the
+damping function enjoys locally a prescribed homogeneity near the undamped set
+in traversal directions. We prove a sharp decay estimate at a polynomial rate
+that depends on the homogeneity of the damping function. Our method relies on a
+refined microlocal analysis linked to a second microlocalization procedure to
+cut the phase space into tiny regions respecting the uncertainty principle but
+way too small to enter a standard semi-classical analysis localization. Using a
+multiplier method, we obtain the energy estimates in each region and we then
+patch the microlocal estimates together.",1411.7271v1
+2014-12-05,Entanglement Dynamics of Quantum Oscillators Nonlinearly Coupled to Thermal Environments,"We study the asymptotic entanglement of two quantum harmonic oscillators
+nonlinearly coupled to an environment. Coupling to independent baths and a
+common bath are investigated. Numerical results obtained using the
+Wangsness-Bloch-Redfield method are supplemented by analytical results in the
+rotating wave approximation. The asymptotic negativity as function of
+temperature, initial squeezing and coupling strength, is compared to results
+for systems with linear system-reservoir coupling. We find that due to the
+parity conserving nature of the coupling, the asymptotic entanglement is
+considerably more robust than for the linearly damped cases. In contrast to
+linearly damped systems, the asymptotic behavior of entanglement is similar for
+the two bath configurations in the nonlinearly damped case. This is due to the
+two-phonon system-bath exchange causing a supression of information exchange
+between the oscillators via the bath in the common bath configuration at low
+temperatures.",1412.1999v1
+2014-12-08,The dispersion modification of electrostatic geodesic acoustic mode by electron geodesic drift current,"The past studies treated the perturbed distribution of circulating electrons
+as adiabatic one when studying the dispersion relation of electrostatic
+geodesic acoustic mode(GAM). In this paper, the flow of electron geodesic
+current (FEGC) is added to modify this adiabatic distribution. Based on the
+drift kinetic theory, it is found that FEGC obviously increases the magnitude
+of the standard GAM's frequency and reduces its damping rate. The increase of
+frequency results from the contribution of FEGC to the radial flow. The reason
+for the reduction of damping rate is that when the effect of FEGC counts, the
+new resonant velocity becomes much larger than ions thermal velocity with
+equilibrium distribution obeying Maxwellian distribution, compared with
+unmodified Landau resonant velocity. Especially, FEGC changes the characters of
+the frequency and damping rate of low-frequency GAM as functions of safety
+factor $q$ .",1412.2481v1
+2014-12-10,Alfvenic Turbulence Beyond the Ambipolar Diffusion Scale,"We investigate the nature of the Alfv\'enic turbulence cascade in two fluid
+MHD simulations in order to determine if turbulence is damped once the ion and
+neutral species become decoupled at a critical scale called the ambipolar
+diffusion scale (L$_{AD}$). Using mode decomposition to separate the three
+classical MHD modes, we study the second order structure functions of the
+Alfv\'en mode velocity field of both neutrals and ions in the reference frame
+of the local magnetic field. On scales greater than L$_{AD}$ we confirm that
+two fluid turbulence strongly resembles single fluid MHD turbulence. Our
+simulations show that the behavior of two fluid turbulence becomes more complex
+on scales less than L$_{AD}$. We find that Alfvenic turbulence can exist past
+L$_{AD}$ when the turbulence is globally super-Alfv\'enic, with the ions and
+neutrals forming separate cascades once decoupling has taken place. When
+turbulence is globally sub-Alfvenic and hence strongly anisotropic with a large
+separation between the parallel and perpendicular decoupling scales, turbulence
+is damped at L$_{AD}$. We also find that the power spectrum of the kinetic
+energy in the damped regime is consistent with a $k^{-4}$ scaling (in agreement
+with the predictions of Lazarian, Vishniac & Cho 2004).",1412.3452v1
+2015-01-19,"Linear wave action decay entailed by Landau damping in inhomogeneous, nonstationary and anisotropic plasma","This paper addresses the linear propagation of an electron wave in a
+collisionless, inhomogeneous, nonstationary and anisotropic plasma. The plasma
+is characterized by its distribution function, $f_H$, at zero order in the wave
+amplitude. This distribution function, from which are derived all the
+hydrodynamical quantities, may be chosen arbitrarily, provided that it solves
+Vlasov equation. Then, from the linearized version of the electrons equation of
+motion, and from Gauss law, is derived an envelope equation for the wave
+amplitude, assumed to evolve over time and space scales much larger than the
+oscillation periods of the wave. The envelope equation may be cast into an
+equation for the the wave action, derived from Whitham's variational principle,
+that demonstrates the action decay due to Landau damping. Moreover, the Landau
+damping rate is derived at first order in the variations of the wave number and
+frequency. As briefly discussed, this paper generalizes numerous previous works
+on the subject, provides a theoretical basis for heuristic arguments regarding
+the action decay, and also addresses the propagation of an externally driven
+wave.",1501.04485v1
+2015-01-30,A large-scale magnetic shield with 10^6 damping at mHz frequencies,"We present a magnetically shielded environment with a damping factor larger
+than one million at the mHz frequency regime and an extremely low field and
+gradient over an extended volume. This extraordinary shielding performance
+represents an improvement of the state of the art in damping the difficult
+regime of very low-frequency distortions by more than an order of magnitude.
+This technology enables a new generation of high precision measurements in
+fundamental physics and metrology, including searches for new physics far
+beyond the reach of accelerator-based experiments. We discuss the technical
+realization of the shield with its improvements in design.",1501.07861v4
+2015-02-01,A Study on the Impact of Wind Generation on the Stability of Electromechanical Oscillations,"Wind is becoming an increasingly significant source of energy in modern power
+generation. Amongst existing technologies, Variable Speed Wind Turbines (VSWT)
+equipped with Double Fed Induction Generators (DFIG) is widely deployed.
+Consequently, power systems are now experiencing newer power flow patterns and
+operating conditions. This paper investigates the impact of a DFIG based Wind
+Farm (WF) on the stability of electromechanical oscillations. This is achieved
+by performing modal analysis to evaluate the stability of a two-area power
+network when subjected to different wind penetration levels and different
+geographical installed locations. The approach via eigenvalues analysis
+involves the design of voltage and Supplementary Damping Controllers (SDCs)
+that contribute to network damping. The effect of Power System Stabilizer (PSS)
+is also examined for several network conditions. Simulations demonstrate a
+damping improvement up to 933% when the control systems are activated and the
+system operates with 25% wind integration.",1502.00215v1
+2015-02-16,"Biomimetic Staggered Composites with Highly Enhanced Energy Dissipation: Design, Modeling, and Test","We investigate the damping enhancement in a class of biomimetic staggered
+composites via a combination of design, modeling, and experiment. In total,
+three kinds of staggered composites are designed by mimicking the structure of
+bone and nacre. These composite designs are realized by 3D printing a rigid
+plastic and a viscous elastomer simultaneously. Greatly-enhanced energy
+dissipation in the designed composites is observed from both the experimental
+results and theoretical prediction. The designed polymer composites have loss
+modulus up to ~500 MPa, higher than most of the existing polymers. In addition,
+their specific loss modulus (up to 0.43 $Km^2/s^2$) is among the highest of
+damping materials. The damping enhancement is attributed to the large shear
+deformation of the viscous soft matrix and the large strengthening effect from
+the rigid inclusion phase.",1502.04568v1
+2015-02-24,High Quality Yttrium Iron Garnet Grown by Room Temperature Pulsed Laser Deposition and Subsequent Annealing,"We have investigated recrystallization of amorphous Yttrium Iron Garnet (YIG)
+by annealing in oxygen atmosphere. Our findings show that well below the
+melting temperature the material transforms into a fully epitaxial layer with
+exceptional quality, both structural and magnetic.\\ In ferromagnetic resonance
+(FMR) ultra low damping and extremely narrow linewidth can be observed. For a
+56 nm thick layer a damping constant of
+$\alpha$=(6.63$\pm$1.50)$\cdot$10$^{-5}$ is found and the linewidth at 9.6 GHz
+is as small as 1.30$\pm$0.05 Oe which are the lowest values for PLD grown thin
+films reported so far. Even for a 20 nm thick layer a damping constant of
+$\alpha$=(7.51$\pm$1.40)$\cdot$10$^{-5}$ is found which is the lowest value for
+ultrathin films published so far. The FMR linewidth in this case is
+3.49$\pm$0.10 Oe at 9.6 GHz. Our results not only present a method of
+depositing thin film YIG of unprecedented quality but also open up new options
+for the fabrication of thin film complex oxides or even other crystalline
+materials.",1502.06724v2
+2015-03-02,DAMPE silicon tracker on-board data compression algorithm,"The Dark Matter Particle Explorer (DAMPE) is an upcoming scientific satellite
+mission for high energy gamma-ray, electron and cosmic rays detection. The
+silicon tracker (STK) is a sub detector of the DAMPE payload with an excellent
+position resolution (readout pitch of 242um), which measures the incident
+direction of particles, as well as charge. The STK consists 12 layers of
+Silicon Micro-strip Detector (SMD), equivalent to a total silicon area of
+6.5m$^2$. The total readout channels of the STK are 73728, which leads to a
+huge amount of raw data to be dealt. In this paper, we focus on the on-board
+data compression algorithm and procedure in the STK, which was initially
+verified by cosmic-ray measurements.",1503.00415v1
+2015-03-08,MHD Seismology of a loop-like filament tube by observed kink waves,"We report and analyze the observational evidence of global kink oscillations
+in a solar filament as observed in H alpha by National Solar Observatory
+(NSO)/Global Oscillation Network Group (GONG) instrument. An M1.1-class flare
+in active region 11692 on 2013 March 15 induced a global kink mode in the
+filament lying in the south-west of AR11692.We find periods of about 61 - 67
+minutes and damping times of 92 - 117 minutes at three vertical slice positions
+chosen in and around the filament apex. We find that the waves are damped. From
+the observed global kink mode period and damping time scale using the theory of
+resonant absorption we perform prominence seismology. We estimate a lower
+cut-off value for the inhomogeneity length-scale to be around 0.34 - 0.44 times
+the radius of the filament cross-section.",1503.02281v1
+2015-03-13,Comparison of spin-orbit torques and spin pumping across NiFe/Pt and NiFe/Cu/Pt interfaces,"We experimentally investigate spin-orbit torques and spin pumping in NiFe/Pt
+bilayers with direct and interrupted interfaces. The damping-like and
+field-like torques are simultaneously measured with spin-torque ferromagnetic
+resonance tuned by a dc bias current, whereas spin pumping is measured
+electrically through the inverse spin Hall effect using a microwave cavity.
+Insertion of an atomically thin Cu dusting layer at the interface reduces the
+damping-like torque, field-like torque, and spin pumping by nearly the same
+factor of ~1.4. This finding confirms that the observed spin-orbit torques
+predominantly arise from diffusive transport of spin current generated by the
+spin Hall effect. We also find that spin-current scattering at the NiFe/Pt
+interface contributes to additional enhancement in magnetization damping that
+is distinct from spin pumping.",1503.04104v3
+2015-03-24,Global weak solutions to compressible quantum Navier-Stokes equations with damping,"The global-in-time existence of weak solutions to the barotropic compressible
+quantum Navier-Stokes equations with damping is proved for large data in three
+dimensional space. The model consists of the compressible Navier-Stokes
+equations with degenerate viscosity, and a nonlinear third-order differential
+operator, with the quantum Bohm potential, and the damping terms. The global
+weak solutions to such system is shown by using the Faedo-Galerkin method and
+the compactness argument. This system is also a very important approximated
+system to the compressible Navier-Stokes equations. It will help us to prove
+the existence of global weak solutions to the compressible Navier-Stokes
+equations with degenerate viscosity in three dimensional space.",1503.06894v4
+2015-03-30,Suppression of Spin Pumping Between Ni$_{80}$Fe$_{20}$ and Cu by a Graphene Interlayer,"We compare ferromagnetic resonance measurements of Permalloy
+Ni$_{80}$Fe$_{20}$ (Py) films sputtered onto Cu(111) films with and without a
+graphene (Gr) interlayer grown by chemical vapor deposition before Py
+deposition. A two-angle sputtering method ensured that neither Gr nor Py was
+degraded by the sample preparation process. We find the expected damping
+enhancement from spin pumping for the Py/Cu case and no detectable enhancement
+for the Py/Gr/Cu case. Since damping is sensitive to effects other than spin
+pumping, we used magnetometry to verify that differences in Py magnetostatic
+properties are not responsible for the difference in damping. We attribute the
+suppression of spin pumping in Py/Gr/Cu to the large contact resistance of the
+Gr/Cu interface.",1503.08777v1
+2015-04-02,Protecting the $\sqrt{SWAP}$ operation from general and residual errors by continuous dynamical decoupling,"We study the occurrence of errors in a continuously decoupled two-qubit state
+during a $\sqrt{SWAP}$ quantum operation under decoherence. We consider a
+realization of this quantum gate based on the Heisenberg exchange interaction,
+which alone suffices for achieving universal quantum computation. Furthermore,
+we introduce a continuous-dynamical-decoupling scheme that commutes with the
+Heisenberg Hamiltonian to protect it from the amplitude damping and dephasing
+errors caused by the system-environment interaction. We consider two
+error-protection settings. One protects the qubits from both amplitude damping
+and dephasing errors. The other features the amplitude damping as a residual
+error and protects the qubits from dephasing errors only. In both settings, we
+investigate the interaction of qubits with common and independent environments
+separately. We study how errors affect the entanglement and fidelity for
+different environmental spectral densities.",1504.00592v1
+2015-04-07,Damped Oscillating Dark Energy: Ideal Fluid and Scalar-Tensor description,"In this paper, we study damped oscillating form of dark energy for explaining
+dynamics of universe. First of all, we consider universe is filled with an
+ideal fluid which has damped oscillating dark energy in terms of this case we
+calculate several physical quantities such as Hubble parameter, acceleration
+parameter, energy density, pressure and others for dark energy, dark
+energy-matter coupling and non-coupling cases. Secondly, we consider as
+universe is filled with scalar field instead of an ideal fluid we obtain these
+physical quantities in terms of scalar potential and kinetic term for the same
+cases in scalar-tensor formalism. Finally, we show that ideal fluid description
+and scalar-tensor description of dark energy give mathematically equivalent
+results for this EoS parameter, even if they haven't same physical meaning.",1504.01509v2
+2015-04-17,Temperature-dependent Plasmons and Their Damping Rates for Graphene with a Finite Energy Bandgap,"We obtained numerical and closed-form analytic expressions for
+finite-temperature plasmon dispersion relations for intrinsic graphene in the
+presence of a finite energy gap in the energy spectrum. The calculations were
+carried out using the random-phase approximation. The analytic results have
+been derived in the high temperature regime and long-wavelength limit. We have
+found that the plasmon damping rate decreases in the presence of a band gap.
+Our method of calculation could also be applied to silicene and other buckled
+honeycomb lattice structures. The finite-temperature plasmon dispersion
+relations are presented when a single graphene layer is Coulomb coupled to a
+semi infinite conductor. Both cases of gapless and gapped monolayer graphene
+have been investigated when a thick substrate is in their proximity. Both the
+plasmon excitation frequency and damping rate are linear functions of the
+in-plane wave vector in the long wavelength limit when a monolayer interacts
+with a conducting substrate which is not the case for free-standing pristine or
+gapped graphene.",1504.04552v1
+2015-05-09,"Existence, general decay and blow-up of solutions for a viscoelastic Kirchhoff equation with Balakrishnan-Taylor damping and dynamic boundary conditions","Our aim in this article is to study a nonlinear viscoelastic Kirchhoff
+equation with strong damping, Balakrishnan-Taylor damping, nonlinear source and
+dynamical boundary condition. Firstly, we prove the local existence of
+solutions by using the Faedo-Galerkin approximation method combined with a
+contraction mapping theorem. We then prove that if the initial data enter into
+the stable set, the solution globally exists, and if the initial data enter
+into the unstable set, the solution blows up in a finite time. Moreover, we
+obtain a general decay result of the energy, from which the usual exponential
+and polynomial decay rates are only special cases.",1505.02220v3
+2015-06-03,Migration of two massive planets into (and out of) first order mean motion resonances,"We consider the dynamical evolution of two planets orbiting in the vicinity
+of a first order mean motion reso- nance while simultaneously undergoing
+eccentricity damping and convergent migration. Following Goldreich &
+Schlichting (2014), we include a coupling between the dissipative semimajor
+axis evolution and the damping of the eccentricities. In agreement with past
+studies, we find that this coupling can lead to overstability of the resonance
+and that for a certain range of parameters capture into resonance is only
+temporary. Using a more general model, we show that whether overstable motion
+can occur depends in a characteristic way on the mass ratio between the two
+planets as well as their relative eccentricity damping timescales. Moreover, we
+show that even when escape from resonance does occur, the timescale for escape
+is long enough such at any given time a pair of planets is more likely to be
+found in a resonance rather than migrating between them. Thus, we argue that
+overstability of resonances cannot singlehandedly reconcile convergent
+migration with the observed lack of Kepler planet pairs found near resonances.
+However, it is possible that overstable motion in combination with other
+effects such as large scale orbital instability could produce the observed
+period ratio distribution.",1506.01382v1
+2015-06-12,"Linear inviscid damping for monotone shear flows in a finite periodic channel, boundary effects, blow-up and critical Sobolev regularity","In a previous article, \cite{Zill3}, we have established linear inviscid
+damping for a large class of monotone shear flows in a finite periodic channel
+and have further shown that boundary effects asymptotically lead to the
+formation of singularities of derivatives of the solution. As the main results
+of this article, we provide a detailed description of the singularity formation
+and establish stability in all sub-critical fractional Sobolev spaces and
+blow-up in all super-critical spaces. Furthermore, we discuss the implications
+of the blow-up to the problem of nonlinear inviscid damping in a finite
+periodic channel, where high regularity would be essential to control nonlinear
+effects.",1506.04010v1
+2015-06-12,Nonlinear damped partial differential equations and their uniform discretizations,"We establish sharp energy decay rates for a large class of nonlinearly
+first-order damped systems, and we design discretization schemes that inherit
+of the same energy decay rates, uniformly with respect to the space and/or time
+discretization parameters, by adding appropriate numerical viscosity terms. Our
+main arguments use the optimal-weight convexity method and uniform
+observability inequalities with respect to the discretization parameters. We
+establish our results, first in the continuous setting, then for space
+semi-discrete models, and then for time semi-discrete models. The full
+discretization is inferred from the previous results. Our results cover, for
+instance, the Schr\""odinger equation with nonlinear damping, the nonlinear wave
+equation, the nonlinear plate equation, as well as certain classes of equations
+with nonlocal terms.",1506.04163v2
+2015-06-17,Landau Damping of Electrostatic Waves in Arbitrarily Degenerate Quantum Plasmas,"We carry out a systematic study of the dispersion relation for linear
+electrostatic waves in an arbitrarily degenerate quantum electron plasma. We
+solve for the complex frequency spectrum for arbitrary values of wavenumber $k$
+and level of degeneracy $\mu$. Our finding is that for large $k$ and high $\mu$
+the real part of the frequency $\omega_{r}$ grows linearly with $k$ and scales
+with $\mu$ only because of the scaling of the Fermi energy. In this regime the
+relative Landau damping rate $\gamma/\omega_{r}$ becomes independent of $k$ and
+varies inversly with $\mu$. Thus, damping is weak but finite at moderate levels
+of degeneracy for short wavelengths.",1506.05494v2
+2015-06-25,Simultaneous Interconnection and Damping Assignment Passivity-based Control of Mechanical Systems Using Generalized Forces,"To extend the realm of application of the well known controller design
+technique of interconnection and damping assignment passivity-based control
+(IDA-PBC) of mechanical systems two modifications to the standard method are
+presented in this article. First, similarly to [1], it is proposed to avoid the
+splitting of the control action into energy-shaping and damping injection
+terms, but instead to carry them out simultaneously. Second, motivated by [2],
+we propose to consider the inclusion of generalised forces, going beyond the
+gyroscopic ones used in standard IDA-PBC. It is shown that several new
+controllers for mechanical systems designed invoking other (less systematic
+procedures) that do not satisfy the conditions of standard IDA-PBC, actually
+belong to this new class of SIDA-PBC.",1506.07679v1
+2015-07-20,Bifurcation of the quasinormal spectrum and Zero Damped Modes for rotating dilatonic black holes,"It has been recently found that for the near extremal Kerr black holes
+appearing of Zero Damped Modes (accompanied by qusinormal mode branching)
+signifies about inapplicability of the regime of small perturbations and the
+onset of turbulence. Here we show that this phenomena is not limited by Kerr or
+Kerr-Newman solutions only, but also takes place for rotating dilatonic black
+holes for which we have found Zero Damped Modes both numerically and
+analytically. We have also shown that, contrary to recent claims, there is no
+instability of a charged massive scalar field in the background of the rotating
+dilatonic black hole under physically adequate boundary conditions. Analytic
+expression for dominant quasinormal frequencies is deduced in the regime of
+large coupling qQ, where q and Q are the field and black hole charges
+respectively.",1507.05649v1
+2015-08-05,Quantum discord protection from amplitude damping decoherence,"Entanglement is known to be an essential resource for many quantum
+information processes. However, it is now known that some quantum features may
+be acheived with quantum discord, a generalized measure of quantum correlation.
+In this paper, we study how quantum discord, or more specifically, the measures
+of entropic discord and geometric discord are affected by the influence of
+amplitude damping decoherence. We also show that a protocol deploying weak
+measurement and quantum measurement reversal can effectively protect quantum
+discord from amplitude damping decoherence, enabling to distribute quantum
+correlation between two remote parties in a noisy environment.",1508.00972v1
+2015-09-27,On the well-posedness and asymptotic behavior of the generalized KdV-Burgers equation,"In this paper we are concerned with the well-posedness and the exponential
+stabilization of the generalized Korteweg-de Vries Burgers equation, posed on
+the whole real line, under the effect of a damping term. Both problems are
+investigated when the exponent p in the nonlinear term ranges over the interval
+$[1,5)$. We first prove the global well-posedness in $H^s(R)$, for $0 \leq s
+\leq 3$ and $1 \leq p < 2$, and in $H^3(R)$, when $p \geq 2$. For $2 \leq p <
+5$, we prove the existence of global solutions in the $L^2$-setting. Then, by
+using multiplier techniques combined with interpolation theory, the exponential
+stabilization is obtained for a indefinite damping term and $1 \leq p < 2$.
+Under the effect of a localized damping term the result is obtained when $2
+\leq p < 5$. Combining multiplier techniques and compactness arguments it is
+shown that the problem of exponential decay is reduced to prove the unique
+continuation property of weak solutions",1509.08148v1
+2015-10-11,Error estimates of finite element method for semi-linear stochastic strongly damped wave equation,"In this paper, we consider a semi-linear stochastic strongly damped wave
+equation driven by additive Gaussian noise. Following a semigroup framework, we
+establish existence, uniqueness and space-time regularity of a mild solution to
+such equation. Unlike the usual stochastic wave equation without damping, the
+underlying problem with space-time white noise (Q = I) allows for a mild
+solution with a positive order of regularity in multiple spatial dimensions.
+Further, we analyze a spatio-temporal discretization of the problem, performed
+by a standard finite element method in space and a well-known linear implicit
+Euler scheme in time. The analysis of the approximation error forces us to
+significantly enrich existing error estimates of semidiscrete and fully
+discrete finite element methods for the corresponding linear deterministic
+equation. The main results show optimal convergence rates in the sense that the
+orders of convergence in space and in time coincide with the orders of the
+spatial and temporal regularity of the mild solution, respectively. Numerical
+examples are finally included to confirm our theoretical findings.",1510.03028v1
+2015-11-10,A study of energy correction for the electron beam data in the BGO ECAL of the DAMPE,"The DArk Matter Particle Explorer (DAMPE) is an orbital experiment aiming at
+searching for dark matter indirectly by measuring the spectra of photons,
+electrons and positrons originating from deep space. The BGO electromagnetic
+calorimeter is one of the key sub-detectors of the DAMPE, which is designed for
+high energy measurement with a large dynamic range from 5 GeV to 10 TeV. In
+this paper, some methods for energy correction are discussed and tried, in
+order to reconstruct the primary energy of the incident electrons. Different
+methods are chosen for the appropriate energy ranges. The results of Geant4
+simulation and beam test data (at CERN) are presented.",1511.02998v1
+2015-11-10,Quantum Fisher and Skew information for Unruh accelerated Dirac qubit,"We develop a Bloch vector representation of Unruh channel for a Dirac field
+mode. This is used to provide a unified, analytical treatment of quantum Fisher
+and Skew information for a qubit subjected to the Unruh channel, both in its
+pure form as well as in the presence of experimentally relevant external noise
+channels. The time evolution of Fisher and Skew information is studied along
+with the impact of external environment parameters such as temperature and
+squeezing. The external noises are modelled by both purely dephasing phase
+damping as well as the squeezed generalized amplitude damping channels. An
+interesting interplay between the external reservoir temperature and squeezing
+on the Fisher and Skew information is observed, in particular, for the action
+of the squeezed generalized amplitude damping channel. It is seen that for some
+regimes, squeezing can enhance the quantum information against the
+deteriorating influence of the ambient environment. Similar features are also
+observed for the analogous study of Skew information, highlighting the similar
+origin of the Fisher and Skew information.",1511.03029v1
+2015-11-23,Detection of high frequency oscillations and damping from multi-slit spectroscopic observations of the corona,"During the total solar eclipse of 11 July 2010, multi-slit spectroscopic
+observations of the solar corona were performed from Easter Island, Chile. To
+search for high-frequency waves, observations were taken at a high cadence in
+the green line at 5303 A due to [Fe xiv] and the red line at 6374 A due to [Fe
+x]. The data are analyzed to study the periodic variations in the intensity,
+Doppler velocity and line width using wavelet analysis. The data with high
+spectral and temporal resolution enabled us to study the rapid dynamical
+changes within coronal structures. We find that at certain locations each
+parameter shows significant oscillation with periods ranging from 6 - 25 s. For
+the first time, we could detect damping of high-frequency oscillations with
+periods of the order of 10 s. If the observed damped oscillations are due to
+magnetohydrodynamic (MHD) waves then they can contribute significantly in the
+heating of the corona. From a statistical study we try to characterize the
+nature of the observed oscillations while looking at the distribution of power
+in different line parameters.",1511.07160v1
+2015-11-26,Uniform exponential stability of Galerkin approximations for damped wave systems,"We consider the numerical approximation of linear damped wave systems by
+Galerkin approximations in space and appropriate time-stepping schemes. Based
+on a dissipation estimate for a modified energy, we prove exponential decay of
+the physical energy on the continuous level provided that the damping is
+effective everywhere in the domain. The methods of proof allow us to analyze
+also a class of Galerkin approximations based on a mixed variational
+formulation of the problem. Uniform exponential stability can be guaranteed for
+these approximations under a general compatibility condition on the
+discretization spaces. As a particular example, we discuss the discretization
+by mixed finite element methods for which we obtain convergence and uniform
+error estimates under minimal regularity assumptions. We also prove
+unconditional and uniform exponential stability for the time discretization by
+certain one-step methods. The validity of the theoretical results as well as
+the necessity of some of the conditions required for our analysis are
+demonstrated in numerical tests.",1511.08341v1
+2015-12-01,Epitaxial patterning of nanometer-thick Y3Fe5O12 films with low magnetic damping,"Magnetic insulators such as yttrium iron garnet, Y3Fe5O12, with extremely low
+magnetic damping have opened the door for low power spin-orbitronics due to
+their low energy dissipation and efficient spin current generation and
+transmission. We demonstrate reliable and efficient epitaxial growth and
+nanopatterning of Y3Fe5O12 thin-film based nanostructures on insulating
+Gd3Ga5O12 substrates. In particular, our fabrication process is compatible with
+conventional sputtering and liftoff, and does not require aggressive ion
+milling which may be detrimental to the oxide thin films. Structural and
+magnetic properties indicate good qualities, in particular low magnetic damping
+of both films and patterned structures. The dynamic magnetic properties of the
+nanostructures are systematically investigated as a function of the lateral
+dimension. By comparing to ferromagnetic nanowire structures, a distinct edge
+mode in addition to the main mode is identified by both experiments and
+simulations, which also exhbits cross-over with the main mode upon varying the
+width of the wires. The non-linear evolution of dynamic modes over
+nanostructural dimensions highlights the important role of size confinement to
+their material properties in magnetic devices where Y3Fe5O12 nanostructures
+serve as the key functional component.",1512.00286v1
+2015-12-03,Probing Bogoliubov quasiparticles in superfluid $^3$He with a 'vibrating-wire like' MEMS device,"We have measured the interaction between superfluid $^3$He-B and a
+micro-machined goalpost-shaped device at temperatures below $0.2\,T_c$. The
+measured damping follows well the theory developed for vibrating wires, in
+which the Andreev reflection of quasiparticles in the flow field around the
+moving structure leads to a nonlinear frictional force. At low velocities the
+damping force is proportional to velocity while it tends to saturate for larger
+excitations. Above a velocity of 2.6$\,$mms$^{-1}$ the damping abruptly
+increases, which is interpreted in terms of Cooper-pair breaking.
+Interestingly, this critical velocity is significantly lower than reported with
+other mechanical probes immersed in superfluid $^3$He. Furthermore, we report
+on a nonlinear resonance shape for large motion amplitudes that we interpret as
+an inertial effect due to quasiparticle friction, but other mechanisms could
+possibly be invoked as well.",1512.01033v1
+2016-01-03,Event-triggered Communication in Wide-area Damping Control: A Limited Output Feedback Based Approach,"A conceptual design methodology is proposed for event-triggered based power
+system wide area damping controller. The event-triggering mechanism is adopted
+to reduce the communication burden between origin of the remote signal and the
+wide area damping controller (WADC) location. The remote signal is transmitted
+to the WADC only when an event-triggering condition based on a predefined
+system output, is satisfied. The triggering condition is derived from a
+stability criterion, and is monitored continuously by a separate
+event-monitoring unit located at the origin of the remote signal. The stability
+of the resulting closed loop system is guaranteed via the input-to-state
+stability (ISS) technique. The proposed event triggered WADC (ET-WADC) is
+implemented on two typical test power systems - two area four machine and IEEE
+39 bus 10 machine. The validation of proposed mechanism is carried out through
+non-linear simulation studies on MATLAB/Simulink platform. The numerical
+results show the efficacy of the controller in managing the communication
+channel usage without compromising the stated system stability objectives.",1601.00255v1
+2016-01-05,Lie transformation method on quantum state evolution of a general time-dependent driven and damped parametric oscillator,"A variety of dynamics in nature and society can be approximately treated as a
+driven and damped parametric oscillator. An intensive investigation of this
+time-dependent model from an algebraic point of view provides a consistent
+method to resolve the classical dynamics and the quantum evolution in order to
+understand the time-dependent phenomena that occur not only in the macroscopic
+classical scale for the synchronized behaviors but also in the microscopic
+quantum scale for a coherent state evolution. By using a Floquet
+U-transformation on a general time-dependent quadratic Hamiltonian, we exactly
+solve the dynamic behaviors of a driven and damped parametric oscillator to
+obtain the optimal solutions by means of invariant parameters of $K$s to
+combine with Lewis-Riesenfeld invariant method. This approach can discriminate
+the external dynamics from the internal evolution of a wave packet by producing
+independent parametric equations that dramatically facilitate the parametric
+control on the quantum state evolution in a dissipative system. In order to
+show the advantages of this method, several time-dependent models proposed in
+the quantum control field are analyzed in details.",1601.00727v3
+2016-02-19,Distinctive response of many-body localized systems to strong electric field,"We study systems which are close to or within the many-body localized (MBL)
+regime and are driven by strong electric field. In the ergodic regime, the
+disorder extends applicability of the equilibrium linear--response theory to
+stronger drivings, whereas the response of the MBL systems is very distinctive,
+revealing currents with damped oscillations. The oscillation frequency is
+independent of driving and the damping is not due to heating but rather due to
+dephasing. The details of damping depend on the system's history reflecting
+nonergodicity of the MBL phase, while the frequency of the oscillations remains
+a robust hallmark of localization. We show that the distinctive characteristic
+of the driven MBL phase is also a logarithmic increase of the energy and the
+polarization with time.",1602.06055v1
+2016-03-07,Optimal Load and Stiffness for Displacement-Constrained Vibration Energy Harvesters,"The power electronic interface to a vibration energy harvester not only
+provides ac-dc conversion, but can also set the electrical damping to maximize
+output power under displacement-constrained operation. This is commonly
+exploited for linear two-port harvesters by synchronous switching to realize a
+Coulomb-damped resonant generator, but has not been fully explored when the
+harvester is asynchronously switched to emulate a resistive load. In order to
+understand the potential of such an approach, the optimal values of load
+resistance and other control parameters need to be known. In this paper we
+determine analytically the optimal load and stiffness of a harmonically driven
+two-port harvester with displacement constraints. For weak-coupling devices, we
+do not find any benefit of load and stiffness adjustment beyond maintaining a
+saturated power level. For strong coupling we find that the power can be
+optimized to agree with the velocity damped generator beyond the first critical
+force for displacement-constrained operation. This can be sustained up to a
+second critical force, determined by a resonator figure-of-merit, at which the
+power ultimately levels out.",1603.01909v1
+2016-03-22,Generation and protection of steady-state quantum correlations due to quantum channels with memory,"We have proposed a scheme of the generation and preservation of two-qubit
+steady state quantum correlations through quantum channels where successive
+uses of the channels are correlated. Different types of noisy channels with
+memory, such as amplitude damping, phase-damping, and depolarizing channels
+have been taken into account. Some analytical or numerical results are
+presented. The effect of channels with memory on dynamics of quantum
+correlations has been discussed in detail. The results show that, steady state
+entanglement between two independent qubits without entanglement subject to
+amplitude damping channel with memory can be generated. Besides, we compare the
+dynamics of entanglement with that of quantum discord when a two-qubit system
+is prepared in an entangled state. We show that entanglement dynamics suddenly
+disappears, while quantum discord displays only in the asymptotic limit.
+Two-qubit quantum correlations can be preserved at a long time in the limit of
+$\mu\rightarrow1$.",1603.06676v2
+2016-04-22,Feedback-induced Bistability of an Optically Levitated Nanoparticle: A Fokker-Planck Treatment,"Optically levitated nanoparticles have recently emerged as versatile
+platforms for investigating macroscopic quantum mechanics and enabling
+ultrasensitive metrology. In this article we theoretically consider two damping
+regimes of an optically levitated nanoparticle cooled by cavityless parametric
+feedback. Our treatment is based on a generalized Fokker-Planck equation
+derived from the quantum master equation presented recently and shown to agree
+very well with experiment [1]. For low damping, we find that the resulting
+Wigner function yields the single-peaked oscillator position distribution and
+recovers the appropriate energy distribution derived earlier using a classical
+theory and verified experimentally [2]. For high damping, in contrast, we
+predict a double-peaked position distribution, which we trace to an underlying
+bistability induced by feedback. Unlike in cavity-based optomechanics,
+stochastic processes play a major role in determining the bistable behavior. To
+support our conclusions, we present analytical expressions as well as numerical
+simulations using the truncated Wigner function approach. Our work opens up the
+prospect of developing bistability-based devices, characterization of
+phase-space dynamics, and investigation of the quantum-classical transition
+using levitated nanoparticles.",1604.06767v2
+2016-05-06,Multidimensional Thermoelasticity for Nonsimple Materials -- Well-Posedness and Long-Time Behavior,"An initial-boundary value problem for the multidimensional type III
+thermoelaticity for a nonsimple material with a center of symmetry is
+considered. In the linear case, the well-posedness with and without
+Kelvin-Voigt and/or frictional damping in the elastic part as well as the lack
+of exponential stability in the elastically undamped case is proved. Further, a
+frictional damping for the elastic component is shown to lead to the
+exponential stability. A Cattaneo-type hyperbolic relaxation for the thermal
+part is introduced and the well-posedness and uniform stability under a
+nonlinear frictional damping are obtained using a compactness-uniqueness-type
+argument. Additionally, a connection between the exponential stability and
+exact observability for unitary $C_{0}$-groups is established.",1605.02049v1
+2016-05-16,The Cauchy problem for the nonlinear damped wave equation with slowly decaying data,"We study the Cauchy problem for the nonlinear damped wave equation and
+establish the large data local well-posedness and small data global
+well-posedness with slowly decaying initial data. We also prove that the
+asymptotic profile of the global solution is given by a solution of the
+corresponding parabolic problem, which shows that the solution of the damped
+wave equation has the diffusion phenomena. Moreover, we show blow-up of
+solution and give the estimate of the lifespan for a subcritical nonlinearity.
+In particular, we determine the critical exponent for any space dimension.",1605.04616v2
+2016-05-20,High-frequency behavior of FeN thin films fabricated by reactive sputtering,"We investigated high-frequency behavior of FeN thin films prepared by
+reactive sputtering through ferromagnetic resonance (FMR) and its relationship
+with the static magnetic properties. The FMR was observed in the frequency
+range from 2 to 18 GHz in the FeN films fabricated at proper nitrogen flow rate
+(NFR). In those FeN thin films, a decrease of the saturation magnetization and
+the corresponding decrease of the FMR frequency were observed as NFR was
+increased during the deposition. The external field dependences of the FMR
+frequencies were well fit to the Kittel formula and the Land\'e g-factors
+determined from the fit were found to be very close to the free electron value.
+The high-field damping parameters were almost insensitive to the growth
+condition of NFR. However, the low-field damping parameters exhibited high
+sensitivity to NFR very similar to the dependence of the hard-axis coercivity
+on NFR, suggesting that extrinsic material properties such as impurities and
+defect structures could be important in deciding the low-field damping
+behavior.",1605.06179v1
+2016-05-26,Thickness and temperature dependence of the magnetodynamic damping of pulsed laser deposited $\text{La}_{0.7}\text{Sr}_{0.3}\text{MnO}_3$ on (111)-oriented SrTi$\text{O}_3$,"We have investigated the magnetodynamic properties of
+$\text{La}_{0.7}\text{Sr}_{0.3}\text{MnO}_3$ (LSMO) films of thickness 10, 15
+and 30 nm grown on (111)-oriented SrTi$\text{O}_3$ (STO) substrates by pulsed
+laser deposition. Ferromagnetic resonance (FMR) experiments were performed in
+the temperature range 100--300 K, and the magnetodynamic damping parameter
+$\alpha$ was extracted as a function of both film thickness and temperature. We
+found that the damping is lowest for the intermediate film thickness of 15 nm
+with $\alpha \approx 2 \cdot 10^{-3}$, where $\alpha$ is relatively constant as
+a function of temperature well below the Curie temperature of the respective
+films.",1605.08195v2
+2016-06-08,Effect of quantum noise on deterministic joint remote state preparation of a qubit state via a GHZ channel,"Quantum secure communication brings a new direction for information security.
+As an important component of quantum secure communication, deterministic joint
+remote state preparation (DJRSP) could securely transmit a quantum state with
+100\% success probability. In this paper, we study how the efficiency of DJRSP
+is affected when qubits involved in the protocol are subjected to noise or
+decoherence. Taking a GHZ based DJRSP scheme as an example, we study all types
+of noise usually encountered in real-world implementations of quantum
+communication protocols, i.e., the bit-flip, phase-flip (phase-damping),
+depolarizing, and amplitude-damping noise. Our study shows that the fidelity of
+the output state depends on the phase factor, the amplitude factor and the
+noise parameter in the bit-flip noise, while the fidelity only depends on the
+amplitude factor and the noise parameter in the other three types of noise. And
+the receiver will get different output states depending on the first preparer's
+measurement result in the amplitude-damping noise. Our results will be helpful
+for improving quantum secure communication in real implementation.",1606.02484v2
+2016-06-28,Radiation Damping by Thomson Scattering,"Synchrotron radiation of relativistic electrons in storage rings naturally
+leads to the process of damping of betatron oscillations. Damping time and
+transverse beam emittance can be reduced by wigglers or undulators while the
+beam parameters are still well defined by the common radiation integrals, based
+on the properties of synchrotron radiation. However, the quantum excitation of
+betatron oscillations in principle can be considerably reduced if an electron
+radiation occurs due to the Thomson scattering in the periodic electromagnetic
+field. After a brief introduction we compare radiation properties for different
+cases and suggest the modification of the radiation integrals.",1606.08602v5
+2016-06-29,"Kinodynamic Motion Planning: A Novel Type Of Nonlinear, Passive Damping Forces And Advantages","This article extends the capabilities of the harmonic potential field
+approach to planning to cover both the kinematic and dynamic aspects of a robot
+motion. The suggested approach converts the gradient guidance field from a
+harmonic potential to a control signal by augmenting it with a novel type of
+damping forces called nonlinear, anisotropic, damping forces. The combination
+of the two provides a signal that can both guide a robot and effectively manage
+its dynamics. The kinodynamic planning signal inherits the guidance
+capabilities of the harmonic gradient field. It can also be easily configured
+to efficiently suppress the inertia-induced transients in the robot trajectory
+without compromising the speed of operation. The approach works with
+dissipative systems as well as systems acted on by external forces without
+needing the full knowledge of the system dynamics. Theoretical developments and
+simulation results are provided in this article.",1606.09270v1
+2016-09-02,Particle dynamics and Stochastic Resonance in Periodic potentials,"We have studied the dynamics of a particle in a periodically driven
+underdamped periodic potential. Recent studies have reported the occurrence of
+Stochastic Resonance (SR) in such systems in the high frequency regime, using
+input energy per period of external drive as a quantifier. The particle
+trajectories in these systems can be in two dynamical states characterised by
+their definite energy and phase relation with the external drive. SR is due to
+the noise assisted transition of the particles between these two states. We
+study the role of damping on the occurrence of SR. We show that a driven
+underdamped periodic system exhibits SR only if the damping is below a
+particular limit. To explain this we study the syatem in the deterministic
+regime. The existence of the two dynamical states in the deterministic regime
+is dependent on the amount of damping and the amplitude od external drive. We
+also study the input energy distributions and phase difference of the response
+amplitude with the external drive as afunction of the friction parameter.",1609.00678v1
+2016-09-26,An efficient quantum algorithm for spectral estimation,"We develop an efficient quantum implementation of an important signal
+processing algorithm for line spectral estimation: the matrix pencil method,
+which determines the frequencies and damping factors of signals consisting of
+finite sums of exponentially damped sinusoids. Our algorithm provides a quantum
+speedup in a natural regime where the sampling rate is much higher than the
+number of sinusoid components. Along the way, we develop techniques that are
+expected to be useful for other quantum algorithms as well - consecutive phase
+estimations to efficiently make products of asymmetric low rank matrices
+classically accessible and an alternative method to efficiently exponentiate
+non-Hermitian matrices. Our algorithm features an efficient quantum-classical
+division of labor: The time-critical steps are implemented in quantum
+superposition, while an interjacent step, requiring only exponentially few
+parameters, can operate classically. We show that frequencies and damping
+factors can be obtained in time logarithmic in the number of sampling points,
+exponentially faster than known classical algorithms.",1609.08170v1
+2016-10-01,On the regularization of impact without collision: the Painlevé paradox and compliance,"We consider the problem of a rigid body, subject to a unilateral constraint,
+in the presence of Coulomb friction. We regularize the problem by assuming
+compliance (with both stiffness and damping) at the point of contact, for a
+general class of normal reaction forces. Using a rigorous mathematical
+approach, we recover impact without collision (IWC) in both the inconsistent
+and indeterminate Painlev\'e paradoxes, in the latter case giving an exact
+formula for conditions that separate IWC and lift-off. We solve the problem for
+arbitrary values of the compliance damping and give explicit asymptotic
+expressions in the limiting cases of small and large damping, all for a large
+class of rigid bodies.",1610.00143v2
+2016-11-25,Bulk viscous corrections to screening and damping in QCD at high temperatures,"Non-equilibrium corrections to the distribution functions of quarks and
+gluons in a hot and dense QCD medium modify the ""hard thermal loops"" (HTL). The
+HTLs determine the retarded, advanced, and symmetric (time-ordered) propagators
+for gluons with soft momenta as well as the Debye screening and Landau damping
+mass scales. We compute such corrections to a thermal as well as to a
+non-thermal fixed point.The screening and damping mass scales are sensitive to
+the bulk pressure and hence to (pseudo-) critical dynamical scaling of the bulk
+viscosity in the vicinity of a second-order critical point. This could be
+reflected in the properties of quarkonium bound states in the deconfined phase
+and in the dynamics of soft gluon fields.",1611.08379v2
+2016-12-07,Investigation of Stimulated Brillouin Scattering in Laser-Plasma Interactions,"In this paper, we present our numerical simulation results on the Stimulated
+Brillouin Scattering (SBS) with injection of an ordinary mode (O-mode)
+electromagnetic wave (our pump wave) with frequencies 70 GHz and 110 GHz.
+Solving the Fourier transformed Vlasov equation in the velocity space, creates
+a profile for distribution function. Time evolution of the distribution
+function is investigated as well. Considering an average density for plasma
+fusion (n_{0} ~ 10^{19} m^{-3}), we gain a profile for density. Then
+two-dimensional instability rate for SBS is obtained. So, the fluctuation of
+distribution function affects density and again density affects instability
+rate. Increasing the incident light wave frequency causes the instability
+growth rate to decrease. Time evolution shows a clear damping for instability
+rate since the pump wave's energy is absorbed in plasma (plasma heating).
+Furthermore, changing Landau damping for ion acoustic waves (IAW) by changing
+ion-to-electron temperature ratio is presented as well, because this damping is
+more dominant in high temperatures.",1612.02214v1
+2016-12-08,Damped spin-wave excitations in the itinerant antiferromagnet $γ$-Fe$_{0.7}$Mn$_{0.3}$,"The collective spin-wave excitations in the antiferromagnetic state of
+$\gamma$-Fe$_{0.7}$Mn$_{0.3}$ were investigated using the inelastic neutron
+scattering technique. The spin excitations remain isotropic up to the high
+excitation energy, ${\hbar\omega}= 78$ meV. The excitations gradually become
+broad and damped above 40 meV. The damping parameter ${\gamma}$ reaches 110(16)
+meV at ${\hbar\omega} = 78$ meV, which is much larger than that for other
+metallic compounds, e.g., CaFe$_2$As$_2$ (24 meV),
+La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ ($52-72$ meV), and Mn$_{90}$Cu$_{10}$ (88
+meV). In addition, the spin-wave dispersion shows a deviation from the relation
+$({\hbar\omega})^2 = c^2q^2 + {\Delta}^2$ above 40 meV. The group velocity
+above this energy increases to 470(40) meV{\AA}, which is higher than that at
+the low energies, $c = 226(5)$ meV{\AA}. These results could suggest that the
+spin-wave excitations merge with the continuum of the individual particle-hole
+excitations at 40 meV.",1612.02515v2
+2016-12-09,How strong a logistic damping can prevent blow-up for the minimal Keller-Segel chemotaxis system?,"In this paper, we study the minimal Keller-Segel model with a logistic source
+and obtain quantitative and qualitative descriptions of the competition between
+logistic damping and other ingredient, especially, chemotactic aggregation to
+guarantee boundedness and convergence. More specifically, we establish how
+precisely strong a logistic source can prevent blow-up, and then we obtain an
+explicit relationship between logistic damping and other ingredient,
+especially, chemotactic aggregation so that convergences are ensured and their
+respective convergence rates are explicitly calculated out. Known results in
+the literature are completed and refined.
+  Furthermore, our findings provide clues on how to produce blowup solutions
+for KS chemotaxis models with logistic sources.",1612.03024v2
+2016-12-28,Quantum coherence of two-qubit over quantum channels with memory,"Using the axiomatic definition of the coherence measure, such as the $l_{1}$
+norm and the relative entropy, we study the phenomena of two-qubit system
+quantum coherence through quantum channels where successive uses of the
+channels are memory. Different types of noisy channels with memory, such as
+amplitude damping, phase-damping, and depolarizing channels effect on quantum
+coherence have been discussed in detail. The results show that, quantum
+channels with memory can efficiently protect coherence from noisy channels.
+Particularly, as channels with perfect memory, quantum coherence is unaffected
+by the phase damping as well as depolarizing channels. Besides, we also
+investigate the cohering and decohering power of quantum channels with memory.",1612.08791v1
+2017-01-04,Hamiltonian of mean force and a damped harmonic oscillator in an anisotropic medium,"The quantum dynamics of a damped harmonic oscillator is investigated in the
+presence of an anisotropic heat bath. The medium is modeled by a continuum of
+three dimensional harmonic oscillators and anisotropic coupling is treated by
+introducing tensor coupling functions. Starting from a classical Lagrangian,
+the total system is quantized in the framework of the canonical quantization.
+Following Fano technique, Hamiltonian of the system is diagonalized in terms of
+creation and annihilation operators that are linear combinations of the basic
+dynamical variables. Using the diagonalized Hamiltonian, the mean force
+internal energy, free energy and entropy of the damped oscillator are
+calculated.",1701.00964v2
+2017-01-30,Quantization of energy and weakly turbulent profiles of the solutions to some damped second order evolution equations,"We consider a second order equation with a linear ""elastic"" part and a
+nonlinear damping term depending on a power of the norm of the velocity. We
+investigate the asymptotic behavior of solutions, after rescaling them suitably
+in order to take into account the decay rate and bound their energy away from
+zero.We find a rather unexpected dichotomy phenomenon. Solutions with finitely
+many Fouriercomponents are asymptotic to solutions of the linearized
+equationwithout damping, and exhibit some sort of equipartition of theenergy
+among the components. Solutions with infinitely manyFourier components tend to
+zero weakly but not strongly. We showalso that the limit of the energy of
+solutions depends only on thenumber of their Fourier components.The proof of
+our results is inspired by the analysis of asimplified model which we devise
+through an averaging procedure,and whose solutions exhibit the same asymptotic
+properties as thesolutions to the original equation.",1701.08604v1
+2017-02-15,Topological Properties of a Coupled Spin-Photon System Induced by Damping,"We experimentally examine the topological nature of a strongly coupled
+spin-photon system induced by damping. The presence of both spin and photonic
+losses results in a non-Hermitian system with a variety of exotic phenomena
+dictated by the topological structure of the eigenvalue spectra and the
+presence of an exceptional point (EP), where the coupled spin-photon
+eigenvectors coalesce. By controlling both the spin resonance frequency and the
+spin-photon coupling strength we observe a resonance crossing for
+cooperativities above one, suggesting that the boundary between weak and strong
+coupling should be based on the EP location rather than the cooperativity.
+Furthermore we observe dynamic mode switching when encircling the EP and
+identify the potential to engineer the topological structure of coupled
+spin-photon systems with additional modes. Our work therefore further
+highlights the role of damping within the strong coupling regime, and
+demonstrates the potential and great flexibility of spin-photon systems for
+studies of non-Hermitian physics.",1702.04797v2
+2017-02-22,Modified quantum-speed-limit bounds for open quantum dynamics in quantum channels,"The minimal evolution time between two distinguishable states is of
+fundamental interest in quantum physics. Very recently Mirkin et al. argue that
+some most common quantum-speed-limit (QSL) bounds which depend on the actual
+evolution time do not cleave to the essence of the QSL theory as they grow
+indefinitely but the final state is reached at a finite time in a damped
+Jaynes-Cummings (JC) model. In this paper, we thoroughly study this puzzling
+phenomenon. We find the inconsistent estimates will happen if and only if the
+limit of resolution of a calculation program is achieved, through which we
+propose that the nature of the inconsistency is not a violation to the essence
+of the QSL theory but an illusion caused by the finite precision in numerical
+simulations. We also present a generic method to overcome the inconsistent
+estimates and confirm its effectiveness in both amplitude-damping and
+phase-damping channels. Additionally, we show special cases which may restrict
+the QSL bound defined by ""quantumness"".",1702.06748v3
+2017-03-07,Lower Bound and optimality for a nonlinearly damped Timoshenko system with thermoelasticity,"In this paper, we consider a vibrating nonlinear Timoshenko system with
+thermoelasticity with second sound. We first investigate the strong stability
+of this system, then we devote our efforts to obtain the strong lower energy
+estimates using Alabau--Boussouira's energy comparison principle introduced in
+\cite{2} (see also \cite{alabau}). One of the main advantages of these results
+is that they allows us to prove the optimality of the asymptotic results (as
+$t\rightarrow \infty$) obtained in \cite{ali}. We also extend to our model the
+nice results achieved in \cite{alabau} for the case of nonlinearly damped
+Timoshenko system with thermoelasticity. The optimality of our results is also
+investigated through some explicit examples of the nonlinear damping term. The
+proof of our results relies on the approach in \cite{AB1, AB2}.",1703.02599v4
+2017-03-08,A Parameterized Energy Correction Method for Electromagnetic Showers in BGO-ECAL of DAMPE,"DAMPE is a space-based mission designed as a high energy particle detector
+measuring cosmic-rays and $\gamma-$rays which was successfully launched on
+Dec.17, 2015. The BGO electromagnetic calorimeter is one of the key
+sub-detectors of DAMPE for energy measurement of electromagnetic showers
+produced by $e^{\pm}/{\gamma}$. Due to energy loss in dead material and energy
+leakage outside the calorimeter, the deposited energy in BGO underestimates the
+primary energy of incident $e^{\pm}/{\gamma}$. In this paper, based on detailed
+MC simulations, a parameterized energy correction method using the lateral and
+longitudinal information of electromagnetic showers has been studied and
+verified with data of electron beam test at CERN. The measurements of energy
+linearity and resolution are significantly improved by applying this correction
+method for electromagnetic showers.",1703.02821v2
+2017-03-08,A GAMP Based Low Complexity Sparse Bayesian Learning Algorithm,"In this paper, we present an algorithm for the sparse signal recovery problem
+that incorporates damped Gaussian generalized approximate message passing
+(GGAMP) into Expectation-Maximization (EM)-based sparse Bayesian learning
+(SBL). In particular, GGAMP is used to implement the E-step in SBL in place of
+matrix inversion, leveraging the fact that GGAMP is guaranteed to converge with
+appropriate damping. The resulting GGAMP-SBL algorithm is much more robust to
+arbitrary measurement matrix $\boldsymbol{A}$ than the standard damped GAMP
+algorithm while being much lower complexity than the standard SBL algorithm. We
+then extend the approach from the single measurement vector (SMV) case to the
+temporally correlated multiple measurement vector (MMV) case, leading to the
+GGAMP-TSBL algorithm. We verify the robustness and computational advantages of
+the proposed algorithms through numerical experiments.",1703.03044v2
+2017-04-13,Quantum behaviour of open pumped and damped Bose-Hubbard trimers,"We propose and analyse analogs of optical cavities for atoms using three-well
+inline Bose-Hubbard models with pumping and losses. With one well pumped and
+one damped, we find that both the mean-field dynamics and the quantum
+statistics show a qualitative dependence on the choice of damped well. The
+systems we analyse remain far from equilibrium, although most do enter a
+steady-state regime. We find quadrature squeezing, bipartite and tripartite
+inseparability and entanglement, and states exhibiting the EPR paradox,
+depending on the parameter regimes. We also discover situations where the
+mean-field solutions of our models are noticeably different from the quantum
+solutions for the mean fields. Due to recent experimental advances, it should
+be possible to demonstrate the effects we predict and investigate in this
+article.",1704.04021v1
+2017-05-10,Negative mobility of a Brownian particle: strong damping regime,"We study impact of inertia on directed transport of a Brownian particle under
+non-equilibrium conditions: the particle moves in a one-dimensional periodic
+and symmetric potential, is driven by both an unbiased time-periodic force and
+a constant force, and is coupled to a thermostat of temperature T. Within
+selected parameter regimes this system exhibits negative mobility, which means
+that the particle moves in the direction opposite to the direction of the
+constant force. It is known that in such a setup the inertial term is essential
+for the emergence of negative mobility and it cannot be detected in the
+limiting case of overdamped dynamics. We analyse inertial effects and show that
+negative mobility can be observed even in the strong damping regime. We
+determine the optimal dimensionless mass for the presence of negative mobility
+and reveal three mechanisms standing behind this anomaly: deterministic
+chaotic, thermal noise induced and deterministic non-chaotic. The last origin
+has never been reported. It may provide guidance to the possibility of
+observation of negative mobility for strongly damped dynamics which is of
+fundamental importance from the point of view of biological systems, all of
+which in situ operate in fluctuating environments.",1705.03661v1
+2017-05-27,Power System Supplementary Damping Controllers in the Presence of Saturation,"This paper presents the analysis and a method to design supplementary damping
+controllers (SDCs) for synchronous generators considering the effects of
+saturation limits. Usually such saturations of control signals are imposed in
+order to enforce practical limitations such as component ratings. However, to
+guarantee the stability in the presence of saturation limits, the state
+trajectories must remain inside the domain of attraction (DA). In this paper,
+the domain of attraction of a single-machine infinite-bus (SMIB) power system
+with saturation nonlinearity is estimated and compared with the exact
+description of the null controllable region. Then, state-feedback controllers
+are designed to enlarge the DA. Our analysis shows that nonlinear effects of
+saturation should be considered to guarantee stability and satisfactory
+performance. Simulation results on a detailed nonlinear model of a synchronous
+generator indicate that the DA enlarges with the proposed controller. The
+results also indicate that Critical Clearing Time (CCT) and damping of the
+system with saturation can be improved by the proposed method.",1705.09849v1
+2017-05-26,Absence of Landau damping in driven three-component Bose-Einstein condensate in optical lattices,"We explore the quantum many-body physics of a three-component Bose-Einstein
+condensate (BEC) in an optical lattices driven by laser fields in $V$ and
+$\Lambda$ configurations. We obtain exact analytical expressions for the energy
+spectrum and amplitudes of elementary excitations, and discover symmetries
+among them. We demonstrate that the applied laser fields induce a gap in the
+otherwise gapless Bogoliubov spectrum. We find that Landau damping of the
+collective modes above the energy of the gap is carried by laser-induced roton
+modes and is considerably suppressed compared to the phonon-mediated damping
+endemic to undriven scalar BECs.",1705.10199v2
+2017-05-31,Low-energy modes of spin-imbalanced Fermi gases in BCS phase,"The low-energy modes of a spin-imbalanced superfluid Fermi gas in the
+Bardeen-Cooper-Schrieffer (BCS) side are studied. The gas is assumed to be
+sufficiently dilute so that the pairing of atoms can be considered effective
+only in s-wave between fermions of different internal state. The order
+parameter at equilibrium is determined by the mean-field approximation, while
+the properties of the collective modes are calculated within a Gaussian
+approximation for the fluctuations of the order parameter. In particular we
+investigate the effects of asymmetry between the populations of the two
+different components and of temperature on the frequency and damping of
+collective modes. It is found that the temperature does not much affect the
+frequency and the damping of the modes, whereas an increase of the imbalance
+shifts the frequency toward lower values and enhances the damping sensitively.
+Besides the Bogoliubov-Anderson phonons, we observe modes at zero frequency for
+finite values of the wave-number. These modes indicate that an instability
+develops driving the system toward two separate phases, normal and superfluid.",1705.11162v1
+2017-06-01,Global Stabilization of the Navier-Stokes-Voight and the damped nonlinear wave equations by finite number of feedback controllers,"In this paper we introduce a finite-parameters feedback control algorithm for
+stabilizing solutions of the Navier-Stokes-Voigt equations, the strongly damped
+nonlinear wave equations and the nonlinear wave equation with nonlinear damping
+term, the Benjamin-Bona-Mahony-Burgers equation and the KdV-Burgers equation.
+This algorithm capitalizes on the fact that such infinite-dimensional
+dissipative dynamical systems posses finite-dimensional long-time behavior
+which is represented by, for instance, the finitely many determining parameters
+of their long-time dynamics, such as determining Fourier modes, determining
+volume elements, determining nodes , etc..The algorithm utilizes these finite
+parameters in the form of feedback control to stabilize the relevant solutions.
+For the sake of clarity, and in order to fix ideas, we focus in this work on
+the case of low Fourier modes feedback controller, however, our results and
+tools are equally valid for using other feedback controllers employing other
+spatial coarse mesh interpolants.",1706.00162v1
+2017-06-08,Realistic clocks for a Universe without time,"There are a number of problematic features within the current treatment of
+time in physical theories, including the ""timelessness"" of the Universe as
+encapsulated by the Wheeler-DeWitt equation. This paper considers one
+particular investigation into resolving this issue; a conditional probability
+interpretation that was first proposed by Page and Wooters. Those authors
+addressed the apparent timelessness by subdividing a faux Universe into two
+entangled parts, ""the clock"" and ""the remainder of the Universe"", and then
+synchronizing the effective dynamics of the two subsystems by way of
+conditional probabilities. The current treatment focuses on the possibility of
+using a (somewhat) realistic clock system; namely, a coherent-state description
+of a damped harmonic oscillator. This clock proves to be consistent with the
+conditional probability interpretation; in particular, a standard evolution
+operator is identified with the position of the clock playing the role of time
+for the rest of the Universe. Restrictions on the damping factor are determined
+and, perhaps contrary to expectations, the optimal choice of clock is not
+necessarily one of minimal damping.",1706.02531v1
+2017-06-26,High $β$ Effects on Cosmic Ray Streaming in Galaxy Clusters,"Diffuse, extended radio emission in galaxy clusters, commonly referred to as
+radio halos, indicate the presence of high energy cosmic ray (CR) electrons and
+cluster-wide magnetic fields. We can predict from theory the expected surface
+brightness of a radio halo, given magnetic field and CR density profiles.
+Previous studies have shown that the nature of CR transport can radically
+effect the expected radio halo emission from clusters (Wiener et al. 2013).
+Reasonable levels of magnetohydrodynamic (MHD) wave damping can lead to
+significant CR streaming speeds. But a careful treatment of MHD waves in a high
+$\beta$ plasma, as expected in cluster environments, reveals damping rates may
+be enhanced by a factor of $\beta^{1/2}$. This leads to faster CR streaming and
+lower surface brightnesses than without this effect. In this work we re-examine
+the simplified, 1D Coma cluster simulations (with radial magnetic fields) of
+Wiener et al. (2013) and discuss observable consequences of this high $\beta$
+damping. Future work is required to study this effect in more realistic
+simulations.",1706.08525v2
+2017-07-02,Metastability of Kolmogorov flows and inviscid damping of shear flows,"First, we consider Kolmogorov flow (a shear flow with a sinusoidal velocity
+profile) for 2D Navier-Stokes equation on a torus. Such flows, also called bar
+states, have been numerically observed as one type of metastable states in the
+study of 2D turbulence. For both rectangular and square tori, we prove that the
+non-shear part of perturbations near Kolmogorov flow decays in a time scale
+much shorter than the viscous time scale. The results are obtained for both the
+linearized NS equations with any initial vorticity in L^2, and the nonlinear NS
+equation with initial L^2 norm of vorticity of the size of viscosity. In the
+proof, we use the Hamiltonian structure of the linearized Euler equation and
+RAGE theorem to control the low frequency part of the perturbation. Second, we
+consider two classes of shear flows for which a sharp stability criterion is
+known. We show the inviscid damping in a time average sense for non-shear
+perturbations with initial vorticity in L^2. For the unstable case, the
+inviscid damping is proved on the center space. Our proof again uses the
+Hamiltonian structure of the linearized Euler equation and an instability index
+theory recently developed by Lin and Zeng for Hamiltonian PDEs.",1707.00278v1
+2017-09-06,Linear gyrokinetic investigation of the geodesic acoustic modes in realistic tokamak configurations,"Geodesic acoustic modes (GAMs) are studied by means of the gyrokinetic global
+particle-in-cell code ORB5. Linear electromagnetic simulations in the low
+electron beta limit have been performed, in order to separate acoustic and
+Alfv\'enic time scales and obtain more accurate measurements. The dependence of
+the frequency and damping rate on several parameters such as the safety factor,
+the GAM radial wavenumber and the plasma elongation is studied. All simulations
+have been performed with kinetic electrons with realistic electron/ion mass
+ratio. Interpolating formulae for the GAM frequency and damping rate, based on
+the results of the gyrokinetic simulations, have been derived. Using these
+expressions, the influence of the temperature gradient on the damping rate is
+also investigated. Finally, the results are applied to the study of a real
+discharge of the ASDEX Upgrade tokamak.",1709.01818v1
+2017-09-17,Further insights into the damping-induced self-recovery phenomenon,"In a series of papers, D. E. Chang, et al., proved and experimentally
+demonstrated a phenomenon they termed ""damping-induced self-recovery"". However,
+these papers left a few questions concerning the observed phenomenon unanswered
+- in particular, the effect of the intervening lubricant-fluid and its
+viscosity on the recovery, the abrupt change in behaviour with the introduction
+of damping, a description of the energy dynamics, and the curious occurrence of
+overshoots and oscillations and its dependence on the control law. In this
+paper we attempt to answer these questions through theory. In particular, we
+derive an expression for the infinite-dimensional fluid-stool-wheel system,
+that approximates its dynamics to that of the better understood
+finite-dimensional case.",1709.05596v5
+2017-09-19,An Improved Primal-Dual Interior Point Solver for Model Predictive Control,"We propose a primal-dual interior-point (PDIP) method for solving quadratic
+programming problems with linear inequality constraints that typically arise
+form MPC applications. We show that the solver converges (locally)
+quadratically to a suboptimal solution of the MPC problem. PDIP solvers rely on
+two phases: the damped and the pure Newton phases. Compared to state-of-the-art
+PDIP methods, our solver replaces the initial damped Newton phase (usually used
+to compute a medium-accuracy solution) with a dual solver based on Nesterov's
+fast gradient scheme (DFG) that converges with a sublinear convergence rate of
+order O(1/k^2) to a medium-accuracy solution. The switching strategy to the
+pure Newton phase, compared to the state of the art, is computed in the dual
+space to exploit the dual information provided by the DFG in the first phase.
+Removing the damped Newton phase has the additional advantage that our solver
+saves the computational effort required by backtracking line search. The
+effectiveness of the proposed solver is demonstrated on a 2-dimensional
+discrete-time unstable system and on an aerospace application.",1709.06362v1
+2017-09-22,Nonlinear stage of Benjamin-Feir instability in forced/damped deep water waves,"We study a three-wave truncation of a recently proposed damped/forced
+high-order nonlinear Schr\""odinger equation for deep-water gravity waves under
+the effect of wind and viscosity. The evolution of the norm (wave-action) and
+spectral mean of the full model are well captured by the reduced dynamics.
+Three regimes are found for the wind-viscosity balance: we classify them
+according to the attractor in the phase-plane of the truncated system and to
+the shift of the spectral mean. A downshift can coexist with both net forcing
+and damping, i.e., attraction to period-1 or period-2 solutions. Upshift is
+associated with stronger winds, i.e., to a net forcing where the attractor is
+always a period-1 solution. The applicability of our classification to
+experiments in long wave-tanks is verified.",1709.07850v2
+2017-09-27,On long-time asymptotics for viscous hydrodynamic models of collective behavior with damping and nonlocal interactions,"Hydrodynamic systems arising in swarming modelling include nonlocal forces in
+the form of attractive-repulsive potentials as well as pressure terms modelling
+strong local repulsion. We focus on the case where there is a balance between
+nonlocal attraction and local pressure in presence of confinement in the whole
+space. Under suitable assumptions on the potentials and the pressure functions,
+we show the global existence of weak solutions for the hydrodynamic model with
+viscosity and linear damping. By introducing linear damping in the system, we
+ensure the existence and uniqueness of stationary solutions with compactly
+supported density, fixed mass and center of mass. The associated velocity field
+is zero in the support of the density. Moreover, we show that global weak
+solutions converge for large times to the set of these stationary solutions in
+a suitable sense. In particular cases, we can identify the limiting density
+uniquely as the global minimizer of the free energy with the right mass and
+center of mass.",1709.09290v2
+2017-09-28,Landau Damping with Electron Lenses in Space-Charge Dominated Beams,"Progress on the Intensity Frontier of high energy physics critically depends
+on record high intensity charged particles accelerators. Beams in such machines
+become operationally limited by coherent beam instabilities, particularly
+enhanced in the regime of strong space charge (SC). Usual methods to control
+the instabilities, such as octupole magnets, beam feedback dampers and
+employment of chromatic effects, become less effective and insufficient. In [1]
+it was proposed to employ electron lenses for introduction of sufficient spread
+in particle oscillation frequencies needed for beam stabilization and in [2] it
+was shown that electron lenses are uniquely effective for Landau damping of
+transverse beam instabilities in high energy particle accelerators and their
+employment does not compromise incoherent (single particle) stability, dynamic
+aperture and the beam lifetime. Here we consider an important issue of
+effectiveness of the Landau damping with electron lenses in space-charge
+dominated beams and demonstrate that the desired stability can be assured with
+proper choice of the electron beam parameters and current distributions.",1709.10020v1
+2017-10-13,Hydrodynamic-to-ballistic crossover in Dirac fluid,"We develop an exactly solvable classical kinetic model of transport in Dirac
+materials accounting for strong electron-electron (e-e) and electron-hole (e-h)
+collisions. We use this model to track the evolution of graphene conductivity
+and properties of its collective excitations across the
+hydrodynamic-to-ballistic crossover. We find the relaxation rate of electric
+current by e-e collisions that is possible due to the lack of Galilean
+invariance, and introduce a universal numerical measure of this non-invariance
+in arbitrary dimension. We find the two branches of collective excitations in
+the Dirac fluid: plasmons and electron-hole sound. The sound waves have small
+viscous damping at the neutrality point both in the hydrodynamic and ballistic
+regimes, but acquire large damping due to e-h friction even at slight doping.
+On the contrary, plasmons acquire strong frictional damping at the neutrality
+point and become well-defined in doped samples.",1710.05054v3
+2017-10-13,The second hyperpolarizability of systems described by the space-fractional Schrodinger equation,"The static second hyperpolarizability is derived from the space-fractional
+Schr\""{o}dinger equation in the particle-centric view. The Thomas-Reiche-Kuhn
+sum rule matrix elements and the three-level ansatz determines the maximum
+second hyperpolarizability for a space-fractional quantum system. The total
+oscillator strength is shown to decrease as the space-fractional parameter
+$\alpha$ decreases, which reduces the optical response of a quantum system in
+the presence of an external field. This damped response is caused by the
+wavefunction dependent position and momentum commutation relation. Although the
+maximum response is damped, we show that the one-dimensional quantum harmonic
+oscillator is no longer a linear system for $\alpha \neq 1$, where the second
+hyperpolarizability becomes negative before ultimately damping to zero at the
+lower fractional limit of $\alpha \rightarrow 1/2$.",1710.05099v2
+2017-11-01,Tunable magnetization relaxation of Fe_{2}Cr_{1-x}Co_{x}Si half-metallic Heusler alloys by band structure engineering,"We report a systematic investigation on the magnetization relaxation
+properties of iron-based half-metallic Heusler alloy
+Fe$_{2}$Cr$_{1-x}$Co_${x}$Si (FCCS) thin films using broadband angular-resolved
+ferromagnetic resonance. Band structure engineering through Co doping (x)
+demonstrated by first-principles calculations is shown to tune the intrinsic
+magnetic damping over an order of magnitude, namely 0.01-0.0008. Notably, the
+intrinsic damping constants for samples with high Co concentration are among
+the lowest reported for Heusler alloys and even comparable to magnetic
+insulator yttrium iron garnet. Furthermore, a significant reduction of both
+isotropic and anisotropic contributions of extrinsic damping of the FCCS alloys
+was found in the FCCS films with x=0.5-0.75, which is of particular importance
+for applications. These results demonstrate a practical recipe to tailor
+functional magnetization for Heusler alloy-based spintronics at room
+temperature",1711.00406v1
+2017-11-08,Bulk viscous corrections to screening and damping in the deconfined phase at high temperature,"Non-equilibrium corrections in a hot QCD medium modify the ""hard thermal
+loops"" (HTL) which determine the resummed propagators for gluons with soft
+momenta as well as the Debye screening and Landau damping mass scales. We focus
+on bulk viscous corrections to a thermal fixed point. The screening and damping
+mass scales are sensitive to the bulk pressure and perhaps to (pseudo-)
+critical dynamical scaling of the bulk viscosity in the vicinity of a
+second-order critical point. This would affect the properties of quarkonium
+bound states in the deconfined phase.",1711.03072v1
+2017-11-29,A model explaining neutrino masses and the DAMPE cosmic ray electron excess,"We propose a flavored $U(1)_{e\mu}$ neutrino mass and dark matter~(DM) model
+to explain the recent DArk Matter Particle Explorer (DAMPE) data, which feature
+an excess on the cosmic ray electron plus positron flux around 1.4 TeV. Only
+the first two lepton generations of the Standard Model are charged under the
+new $U(1)_{e\mu}$ gauge symmetry. A vector-like fermion $\psi$, which is our DM
+candidate, annihilates into $e^{\pm}$ and $\mu^{\pm}$ via the new gauge boson
+$Z'$ exchange and accounts for the DAMPE excess. We have found that the data
+favors a $\psi$ mass around 1.5~TeV and a $Z'$ mass around 2.6~TeV, which can
+potentially be probed by the next generation lepton colliders and DM direct
+detection experiments.",1711.10995v2
+2017-11-29,Electrophilic dark matter with dark photon: from DAMPE to direct detection,"The electron-positron excess reported by the DAMPE collaboration recently may
+be explained by an electrophilic dark matter (DM). A standard model singlet
+fermion may play the role of such a DM when it is stablized by some symmetries,
+such as a dark $U(1)_X^{}$ gauge symmetry, and dominantly annihilates into the
+electron-positron pairs through the exchange of a scalar mediator. The model,
+with appropriate Yukawa couplings, can well interpret the DAMPE excess. Naively
+one expects that in this type of models the DM-nucleon cross section should be
+small since there is no tree-level DM-quark interactions. We however find that
+at one-loop level, a testable DM-nucleon cross section can be induced for
+providing ways to test the electrophilic model. We also find that a $U(1)$
+kinetic mixing can generate a sizable DM-nucleon cross section although the
+$U(1)_X^{}$ dark photon only has a negligible contribution to the DM
+annihilation. Depending on the signs of the mixing parameter, the dark photon
+can enhance/reduce the one-loop induced DM-nucleon cross section.",1711.11000v2
+2017-11-30,Leptophilic dark matter in gauged $U(1)_{L_e-L_μ}$ model in light of DAMPE cosmic ray $e^+ + e^-$ excess,"Motivated by the very recent cosmic-ray electron+positron excess observed by
+DAMPE collaboration, we investigate a Dirac fermion dark matter (DM) in the
+gauged $L_e - L_\mu$ model. DM interacts with the electron and muon via the
+$U(1)_{e-\mu}$ gauge boson $Z^{'}$. The model can explain the DAMPE data well.
+Although a non-zero DM-nucleon cross section is only generated at one loop
+level and there is a partial cancellation between $Z^{'}ee$ and $Z^{'}\mu\mu$
+couplings, we find that a large portion of $Z^{'}$ mass is ruled out from
+direct DM detection limit leaving the allowed $Z^{'}$ mass to be close to two
+times of the DM mass. Implications for $pp \to Z^{'} \to 2\ell$ and $pp \to
+2\ell + Z^{'}$ , and muon $g-2$ anomaly are also studied.",1711.11563v3
+2017-12-03,Explaining the DAMPE $e^+ e^-$ excess using the Higgs triplet model with a vector dark matter,"We explain the $e^+ e^-$ excess observed by the DAMPE Collaboration using a
+dark matter model based upon the Higgs triplet model and an additional hidden
+$SU(2)_X$ gauge symmetry. Two of the $SU(2)_X$ gauge bosons are stable due to a
+residual discrete symmetry and serve as the dark matter candidate. We search
+the parameter space for regions that can explain the observed relic abundance,
+and compute the flux of $e^+ e^-$ coming from a nearby dark matter subhalo.
+With the inclusion of background cosmic rays, we show that the model can render
+a good fit to the entire energy spectrum covering the AMS-02, Fermi-LAT and
+DAMPE data.",1712.00793v2
+2017-12-06,Explain DAMPE Results by Dark Matter With Hierarchical Lepton-Specific Yukawa Interactions,"We propose to interpret the DAMPE electron excess at 1.5 TeV through scalar
+or Dirac fermion dark matter (DM) annihilation with doubly charged scalar
+mediators that have lepton-specific Yukawa couplings. Hierarchy of such
+lepton-specific Yukawa couplings is generated through the Froggatt-Nielsen
+mechanism, so that the dark matter annihilation products can be dominantly
+electrons. Stringent constraints from LEP2 on intermediate vector boson
+production can be evaded in our scenarios. In the case of scalar DM, we discuss
+one scenario with DM annihilating directly to leptons and the other scenario
+with DM annihilating to scalar mediators followed by their decays. We also
+discuss the Breit-Wigner resonant enhancement and the Sommerfeld enhancement in
+case that the s-wave annihilation process is small or helicity suppressed. With
+both types of enhancement, constraints on the parameters can be relaxed and new
+ways for model building will be open in explaining the DAMPE results.",1712.02381v3
+2017-12-08,Kinetic damping in the spectra of the spherical impedance probe,"The impedance probe is a measurement device to measure plasma parameter like
+electron density. It consists of one electrode connected to a network analyzer
+via a coaxial cable and is immersed into a plasma. A bias potential superposed
+with an alternating potential is applied to the electrode and the response of
+the plasma is measured. Its dynamical interaction with the plasma in
+electrostatic, kinetic description can be modeled in an abstract notation based
+on functional analytic methods. These methods provide the opportunity to derive
+a general solution, which is given as the response function of the probe-plasma
+system. It is defined by the matrix elements of the resolvent of an appropriate
+dynamical operator. Based on the general solution a residual damping for
+vanishing pressure can be predicted and can only be explained by kinetic
+effects. Within this manuscript an explicit response function of the spherical
+impedance probe is derived. Therefore, the resolvent is determined by its
+algebraic representation based on an expansion in orthogonal basis functions.
+This allows to compute an approximated response function and its corresponding
+spectra. These spectra show additional damping due to kinetic effects and are
+in good agreement with former kinetically determined spectra.",1712.03126v1
+2017-12-14,DAMPE squib? Significance of the 1.4 TeV DAMPE excess,"We present a Bayesian and frequentist analysis of the DAMPE charged cosmic
+ray spectrum. The spectrum, by eye, contained a spectral break at about 1 TeV
+and a monochromatic excess at about 1.4 TeV. The break was supported by a Bayes
+factor of about $10^{10}$ and we argue that the statistical significance was
+resounding. We investigated whether we should attribute the excess to dark
+matter annihilation into electrons in a nearby subhalo. We found a local
+significance of about $3.6\sigma$ and a global significance of about
+$2.3\sigma$, including a two-dimensional look-elsewhere effect by simulating
+1000 pseudo-experiments. The Bayes factor was sensitive to our choices of
+priors, but favoured the excess by about 2 for our choices. Thus, whilst
+intriguing, the evidence for a signal is not currently compelling.",1712.05089v1
+2017-12-15,Radiative Seesaw Model and DAMPE Excess from Leptophilic Gauge Symmetry,"In the light of the $e^{+}+e^{-}$ excess observed by DAMPE experiment, we
+propose an anomaly-free radiative seesaw model with an alternative leptophilic
+$U(1)_X$ gauge symmetry. In the model, only right-handed leptons are charged
+under $U(1)_X$ symmetry. The tiny Dirac neutrino masses are generated at
+one-loop level and charged leptons acquire masses though the type-I seesaw-like
+mechanism with heavy intermediate fermions. In order to cancel the anomaly,
+irrational $U(1)_{X}$ charge numbers are assigned to some new particles. After
+the spontaneous breaking of $U(1)_{X}$ symmetry, the dark $Z_{2}$ symmetry
+could appear as a residual symmetry such that the stability of inert particles
+with irrational charge numbers are guaranteed, naturally leading to stable DM
+candidates. We show that the Dirac fermion DM contained in the model can
+explain the DAMPE excess. Meanwhile, experimental constraints from DM relic
+density, direct detection, LEP and anomalous magnetic moments are satisfied.",1712.05722v2
+2017-12-19,Damping of Josephson oscillations in strongly correlated one-dimensional atomic gases,"We study Josephson oscillations of two strongly correlated one-dimensional
+bosonic clouds separated by a localized barrier. Using a quantum-Langevin
+approach and the exact Tonks-Girardeau solution in the impenetrable-boson
+limit, we determine the dynamical evolution of the particle-number imbalance,
+displaying an effective damping of the Josephson oscillations which depends on
+barrier height, interaction strength and temperature. We show that the damping
+originates from the quantum and thermal fluctuations intrinsically present in
+the strongly correlated gas. Thanks to the density-phase duality of the model,
+the same results apply to particle-current oscillations in a one-dimensional
+ring where a weak barrier couples different angular momentum states.",1712.06949v2
+2017-12-21,The gluon condensation effects in the DAMPE cosmic ray spectrum of electrons and positrons,"Gluons dominate the proton behavior at high energy collisions, they can be
+condensed at ultra high energy. The collisions of the accelerated high energy
+protons with interplanetary matter in cosmic rays will produce a huge number of
+secondary particles at the gluon condensate energy region, which break the
+primary power-law of cosmic rays. The above predictions seem to be consistent
+with the recent DAMPE data concerning the electron plus positron spectra. We
+find that the smoothly broken power-law at $\sim 0.9 TeV$ and $3\sim 4 TeV$ in
+the DAMPE data can be understood as the gluon condensation effects in proton.",1712.07868v2
+2017-12-22,Low-momentum dynamic structure factor of a strongly interacting Fermi gas at finite temperature: The Goldstone phonon and its Landau damping,"We develop a microscopic theory of dynamic structure factor to describe the
+Bogoliubov-Anderson-Goldstone phonon mode and its damping rate in a strongly
+interacting Fermi gas at finite temperature. It is based on a density
+functional approach - the so-called superfluid local density approximation. The
+accuracy of the theory is quantitatively examined by comparing the theoretical
+predictions with the recent experimental measurements for the local dynamic
+structure factor of a nearly homogeneous unitary Fermi gas at low transferred
+momentum {[}S. Hoinka \textit{et al.}, Nat. Phys. \textbf{13}, 943 (2017){]},
+without any free parameters. We calculate the dynamic structure factor as
+functions of temperature and transferred momentum, and determine the
+temperature evolution of the phonon damping rate, by considering the dominant
+decay process of the phonon mode via scatterings off fermionic quasiparticles.
+These predictions can be confronted with future Bragg scattering experiments on
+a unitary Fermi gas near the superfluid transition.",1712.08318v1
+2017-12-22,A brief summary of nonlinear echoes and Landau damping,"In this expository note we review some recent results on Landau damping in
+the nonlinear Vlasov equations, focusing specifically on the recent
+construction of nonlinear echo solutions by the author [arXiv:1605.06841] and
+the associated background. These solutions show that a straightforward
+extension of Mouhot and Villani's theorem on Landau damping to Sobolev spaces
+on $\mathbb T^n_x \times \mathbb R^n_v $ is impossible and hence emphasize the
+subtle dependence on regularity of phase mixing problems. This expository note
+is specifically aimed at mathematicians who study the analysis of PDEs, but not
+necessarily those who work specifically on kinetic theory. However, for the
+sake of brevity, this review is certainly not comprehensive.",1712.08498v1
+2017-12-28,Coherence evolution in two-qubit system going through amplitude damping channel,"In this paper, we analyze the evolution of quantum coherence in a two-qubit
+system going through the amplitude damping channel. After they have gone
+through this channel many times, we analyze the systems with respect to the
+coherence of their output states. When only one subsystem goes through the
+channel, frozen coherence occurs if and only if this subsystem is incoherent
+and an auxiliary condition is satisfied for the other subsystem. When two
+subsystems go through this quantum channel, quantum coherence can be frozen if
+and only if the two subsystems are both incoherent. We also investigate the
+evolution of coherence for maximally incoherent-coherent states and derive an
+equation for the output states after one or two subsystems have gone through
+the amplitude damping channel.",1712.09769v1
+2018-01-09,Balanced Truncation Model Reduction of a Nonlinear Cable-Mass PDE System with Interior Damping,"We consider model order reduction of a nonlinear cable-mass system modeled by
+a 1D wave equation with interior damping and dynamic boundary conditions. The
+system is driven by a time dependent forcing input to a linear mass-spring
+system at one boundary. The goal of the model reduction is to produce a low
+order model that produces an accurate approximation to the displacement and
+velocity of the mass in the nonlinear mass-spring system at the opposite
+boundary. We first prove that the linearized and nonlinear unforced systems are
+well-posed and exponentially stable under certain conditions on the damping
+parameters, and then consider a balanced truncation method to generate the
+reduced order model (ROM) of the nonlinear input-output system. Little is known
+about model reduction of nonlinear input-output systems, and so we present
+detailed numerical experiments concerning the performance of the nonlinear ROM.
+We find that the ROM is accurate for many different combinations of model
+parameters.",1801.02792v1
+2018-01-18,Analytic solutions to various dissipation models of the simple and driven quantum harmonic oscillator,"We obtain analytic solutions to various models of dissipation of the quantum
+harmonic oscillator, employing a simple method in the Wigner function Fourier
+transform description of the system; and study as an exemplification, the
+driven open quantum harmonic oscillator. The environmental models we use are
+based on optical master equations for the zero and finite temperature bath and
+whose open dynamics are described by a Lindblad master equation, and also we
+use the Caldeira-Leggett model for the high temperature limit, in the the under
+damped an the over damped case. Under the Wigner Fourier transform or chord
+function as it has been called, it becomes particularly simple to solve the
+dynamics of the open oscillator in the sense that the dynamics of the system
+are reduced to the application of an evolution matrix related to the damped
+motion of the oscillator.",1801.05943v1
+2018-02-12,Chance-constrained optimal location of damping control actuators under wind power variability,"This paper proposes a new probabilistic energy-based method to determine the
+optimal installation location of electronically-interfaced resources (EIRs)
+considering dynamic reinforcement under wind variability in systems with high
+penetration of wind power. The oscillation energy and total action are used to
+compare the dynamic performance for different EIR locations. A linear
+approximation of the total action critically reduces the computational time
+from hours to minutes. Simulating an IEEE-39 bus system with 30% of power
+generation sourced from wind, a chance-constrained optimization is carried out
+to decide the location of an energy storage system (ESS) adding damping to the
+system oscillations. The results show that the proposed method, selecting the
+bus location that guarantees the best dynamic performance with highest
+probability, is superior to both traditional dominant mode analysis and
+arbitrary benchmarks for damping ratios.",1802.04354v1
+2018-02-21,On the vibron-polaron damping in quasi 1D macromolecular chains,"The properties of the intramolecular vibrational excitation (vibron) in a
+quasi 1D macromolecular structure are studied. It is supposed that due to the
+vibron interaction with optical phonon modes, a vibron might form partially
+dressed small polaron states. The properties of these states are investigated
+in dependence on the basic system parameters and temperature of a thermal bath.
+We also investigate the process of damping of the polaron amplitude as a
+function of temperature and vibron-phonon coupling strength. Two different
+regimes of the polaron damping are found and discussed.",1802.07424v1
+2018-02-27,Impact of damping on superconducting gap oscillations induced by intense Terahertz pulses,"We investigate the interplay between gap oscillations and damping in the
+dynamics of superconductors taken out of equilibrium by strong optical pulses
+with sub-gap Terahertz frequencies. A semi-phenomenological formalism is
+developed to include the damping within the electronic subsystem that arises
+from effects beyond BCS, such as interactions between Bogoliubov quasiparticles
+and decay of the Higgs mode. Such processes are conveniently expressed as
+$T_{1}$ and $T_{2}$ times in the standard pseudospin language for
+superconductors. Comparing with data on NbN that we report here, we argue that
+the superconducting dynamics in the picosecond time scale, after the pump is
+turned off, is governed by the $T_{2}$ process.",1802.09711v2
+2018-02-28,Analysis of imperfections in the coherent optical excitation of single atoms to Rydberg states,"We study experimentally various physical limitations and technical
+imperfections that lead to damping and finite contrast of optically-driven Rabi
+oscillations between ground and Rydberg states of a single atom. Finite
+contrast is due to preparation and detection errors and we show how to model
+and measure them accurately. Part of these errors originates from the finite
+lifetime of Rydberg states and we observe its $n^3$-scaling with the principal
+quantum number $n$. To explain the damping of Rabi oscillations, we use simple
+numerical models, taking into account independently measured experimental
+imperfections, and show that the observed damping actually results from the
+accumulation of several small effects, each at the level of a few percents. We
+discuss prospects for improving the coherence of ground-Rydberg Rabi
+oscillations in view of applications in quantum simulation and quantum
+information processing with arrays of single Rydberg atoms.",1802.10424v1
+2018-03-07,Connecting dissipation and noncommutativity: A Bateman system case study,"Quantum effects on a pair of Bateman oscillators embedded in an ambient
+noncommutative space (Moyal plane) is analyzed using both path integral and
+canonical quantization schemes within the framework of Hilbert-Schmidt operator
+formulation. We adopt a method which is distinct from the one which employs 't
+Hooft's scheme of quantization, carried out earlier in the literature where the
+ambient space was taken to be commutative. Our quantization shows that we end
+up finally again with a Bateman system except that the damping factor undergoes
+renormalization. The corresponding expression shows that the renormalized
+damping factor can be non-zero even if ""bare"" one is zero to begin with.
+Conversely, the noncommuatative parameter $\theta$, taken to be a free one now,
+can be fine-tuned to get a vanishing renormalized damping factor. This
+indicates a duality between dissipative commutative theory and non-dissipative
+noncommutative theory.",1803.03334v1
+2018-03-18,A machine learning method to separate cosmic ray electrons from protons from 10 to 100 GeV using DAMPE data,"DArk Matter Particle Explorer (DAMPE) is a general purpose high energy cosmic
+ray and gamma ray observatory, aiming to detect high energy electrons and
+gammas in the energy range 5 GeV to 10 TeV and hundreds of TeV for nuclei. This
+paper provides a method using machine learning to identify electrons and
+separate them from gammas,protons,helium and heavy nuclei with the DAMPE data
+from 2016 January 1 to 2017 June 30, in energy range from 10 to 100 GeV.",1803.06628v2
+2018-03-20,Estimating Participation Factors and Mode Shapes for Electromechanical Oscillations in Ambient Conditions,"In this paper, a new technique is applied to conduct mode identification
+using ambient measurement data. The proposed hybrid measurement- and
+model-based method can accurately estimate the system state matrix in ambient
+conditions, the eigenvalues and eigenvectors of which readily provide all the
+modal knowledge including frequencies, damping ratios, mode shapes, and more
+importantly, participation factors. Numerical simulations show that the
+proposed technique is able to provide accurate estimation of modal knowledge
+for all modes. In addition, the discrepancy between the participation factor
+and the mode shape is shown through a numerical example, demonstrating that
+using the mode shape may not effectively pinpoint the best location for damping
+control. Therefore, the proposed technique capable of estimating participation
+factors may greatly facilitate designing damping controls.",1803.07264v1
+2018-03-21,Globally Stable Output Feedback Synchronization of Teleoperation with Time-Varying Delays,"This paper presents a globally stable teleoperation control strategy for
+systems with time-varying delays that eliminates the need for velocity
+measurements through novel augmented Immersion and Invariance velocity
+observers. The new observers simplify a recent constructive Immersion and
+Invariance velocity observer to achieve globally convergent velocity estimation
+with only $n+2$ states, where $n$ is the number of degrees of freedom of the
+master and slave robots. They introduce dynamic scaling factors to accelerate
+the speed of convergence of the velocity estimates and, thus, to limit the
+energy generated by the velocity estimation errors and to guarantee sufficient
+estimate-based damping injection to dissipate the energy generated by the
+time-varying delays. The paper shows that Proportional plus damping control
+with the simplified and augmented Immersion and Invariance-based velocity
+observers can synchronize the free master and slave motions in the presence of
+time-varying delays without using velocity measurements. Numerical results
+illustrate the estimation performance of the new observers and the stability of
+a simulated two degrees-of-freedom nonlinear teleoperation system with
+time-varying delays under the proposed output feedback Proportional plus
+damping control.",1803.08159v1
+2018-03-29,Stochastic conformal multi-symplectic method for damped stochastic nonlinear Schrodinger equation,"In this paper, we propose a stochastic conformal multi-symplectic method for
+a class of damped stochastic Hamiltonian partial differential equations in
+order to inherit the intrinsic properties, and apply the numerical method to
+solve a kind of damped stochastic nonlinear Schrodinger equation with
+multiplicative noise. It is shown that the stochastic conformal
+multi-symplectic method preserves the discrete stochastic conformal
+multi-symplectic conservation law, the discrete charge exponential dissipation
+law almost surely, and we also deduce the recurrence relation of the discrete
+global energy. Numerical experiments are preformed to verify the good
+performance of the proposed stochastic conformal multi-symplectic method,
+compared with a Crank-Nicolson type method. Finally, we present the mean square
+convergence result of the proposed numerical method in temporal direction
+numerically.",1803.10885v1
+2018-04-01,Bounded Connectivity-Preserving Coordination of Networked Euler-Lagrange Systems,"This paper derives sufficient conditions for bounded distributed
+connectivity-preserving coordination of Euler-Lagrange systems with only
+position measurements and with system uncertainties, respectively. The paper
+proposes two strategies that suitably scale conventional gradient-based
+controls to account for the actuation bounds and to reserve sufficient
+actuation for damping injection. For output feedback control of networked
+systems with only position measurements, the paper incorporates a first-order
+filter to estimate velocities and to inject damping for stability. For networks
+of uncertain systems, the paper augments conventional linear filter-based
+adaptive compensation with damping injection to maintain the local connectivity
+of the network. Analyses based on monotonically decreasing Lyapunov-like
+functions and Barbalat's lemma lead to sufficient conditions for bounded local
+connectivity-preserving coordination of Euler-Lagrange networks under the two
+strategies. The sufficient conditions clarify the interrelationships among the
+bounded actuations, initial system velocities and initial inter-system
+distances. Simulation results validate these conditions.",1804.00333v1
+2018-04-09,Damping and clustering into crowded environment of catalytic chemical oscillators,"A system formed by a crowded environment of catalytic obstacles and complex
+oscillatory chemical reactions is inquired. The obstacles are static spheres of
+equal radius, which are placed in a random way. The chemical reactions are
+carried out in a fluid following a multiparticle collision scheme where the
+mass, energy and local momentum are conserved. Firstly, it is explored how the
+presence of catalytic obstacles changes the oscillatory dynamics from a limit
+cycle to a fix point reached after a damping. The damping is characterized by
+the decay constant, which grows linearly with volume fraction for low values of
+the mesoscale collision time and the catalytic reaction constant. Additionally,
+it is shown that, although the distribution of obstacles is random, there are
+regions in the system where the catalytic chemical reactions are favored. This
+entails that in average the radius of gyrations of catalytic chemical reaction
+does not match with the radius of gyration of obstacles, that is, clusters of
+reactions emerge on the catalytic obstacles, even when the diffusion is
+significant.",1804.03174v1
+2018-04-17,Modelling linewidths of Kepler red giants in NGC 6819,"We present a comparison between theoretical, frequency-dependent, damping
+rates and linewidths of radial-mode oscillations in red-giant stars located in
+the open cluster NGC 6819. The calculations adopt a time-dependent non-local
+convection model, with the turbulent pressure profile being calibrated to
+results of 3D hydrodynamical simulations of stellar atmospheres. The linewidths
+are obtained from extensive peakbagging of Kepler lightcurves. These
+observational results are of unprecedented quality owing to the long continuous
+observations by Kepler. The uniqueness of the Kepler mission also means that,
+for asteroseismic properties, this is the best data that will be available for
+a long time to come. We therefore take great care in modelling nine RGB stars
+in NGC 6819 using information from 3D simulations to obtain realistic
+temperature stratifications and calibrated turbulent pressure profiles. Our
+modelled damping rates reproduce well the Kepler observations, including the
+characteristic depression in the linewidths around the frequency of maximum
+oscillation power. Furthermore, we thoroughly test the sensitivity of the
+calculated damping rates to changes in the parameters of the nonlocal
+convection model.",1804.06255v1
+2018-04-24,$\text{Co}_{25}\text{Fe}_{75}$ Thin Films with Ultralow Total Damping,"We measure the dynamic properties of $\text{Co}_{25}\text{Fe}_{75}$ thin
+films grown by dc magnetron sputtering. Using ferromagnetic resonance
+spectroscopy, we demonstrate an ultralow total damping parameter in the
+out-of-plane configuration of < 0.0013, whereas for the in-plane configuration
+we find a minimum total damping of < 0.0020. In both cases, we observe low
+inhomogeneous linewidth broadening in macroscopic films. We observe a minimum
+full-width half-maximum linewidth of 1 mT at 10 GHz resonance frequency for a
+12 nm thick film. We characterize the morphology and structure of these films
+as a function of seed layer combinations and find large variation of the
+qualitative behavior of the in-plane linewidth vs. resonance frequency.
+Finally, we use wavevector-dependent Brillouin light scattering spectroscopy to
+characterize the spin-wave dispersion at wave vectors up to 23 $\mu
+\text{m}^{-1}$.",1804.08786v1
+2018-05-15,Simple Nonlinear Models with Rigorous Extreme Events and Heavy Tails,"Extreme events and the heavy tail distributions driven by them are ubiquitous
+in various scientific, engineering and financial research. They are typically
+associated with stochastic instability caused by hidden unresolved processes.
+Previous studies have shown that such instability can be modeled by a
+stochastic damping in conditional Gaussian models. However, these results are
+mostly obtained through numerical experiments, while a rigorous understanding
+of the underlying mechanism is sorely lacking. This paper contributes to this
+issue by establishing a theoretical framework, in which the tail density of
+conditional Gaussian models can be rigorously determined. In rough words, we
+show that if the stochastic damping takes negative values, the tail is
+polynomial; if the stochastic damping is nonnegative but takes value zero, the
+tail is between exponential and Gaussian. The proof is established by
+constructing a novel, product-type Lyapunov function, where a Feynman-Kac
+formula is applied. The same framework also leads to a non-asymptotic large
+deviation bound for long-time averaging processes.",1805.05615v3
+2018-06-18,Theoretical interpretations of DAMPE first results: a critical review,"The DAMPE experiment recently published its first results on the lepton ($e^+
++ e^-$) cosmic-ray (CRs) flux. These results are of importance since they
+account for the first direct detection of the lepton break around the energy of
+1 TeV and confirm the discoveries of ground-based Cherenkov detectors.
+Meanwhile they reveal a new high-energy feature in the spectrum which triggered
+a lot of excitement on the theory side, when interpreted as the typical
+signature of leptophilic dark-matter annihilation. In this proceeding I mainly
+focus on the theoretical understanding of the lepton break. Then I quickly
+review the status of the more speculative line-like DAMPE excess, whose
+astrophysical (pulsar) or exotic (dark matter) explanation is strongly
+constrained by multi-messenger astronomy.",1806.06534v1
+2018-07-17,Bipartite and Tripartite Entanglement for Three Damped Driven Qubits,"We investigate bipartite and tripartite entanglement in an open quantum
+system, specifically three qubits, all of which are damped, and one of which is
+driven. We adapt a systematic approach in calculating the entanglement of
+various bipartite splits usinga generalized concurrence as an indicator of
+entanglement. Our calculations are based on a direct detection scheme that is a
+particular unravelling of the density matrix. This system has a collective
+dipole-dipole energy shift that couples the atoms and the dissipation is via
+partially collective spontaneous emission described by the Lehmberg-Agarwal
+master equation.Our results are unravelling dependent, but apply to
+applications of entanglement based on direct detection. We also calculate the
+three-way tangle or residual entanglement for this system. We present
+calculations for a variety of driving and damping rates, and examine what decay
+rate is adequate for the system to be reduced to two qubits with a readout
+port. We also consider a specific model of three atoms located at particular
+positions in free space.",1807.06178v1
+2018-07-24,Interplay between intermittency and dissipation in collisionless plasma turbulence,"We study the damping of collisionless Alfv\'enic turbulence by two
+mechanisms: stochastic heating (whose efficiency depends on the local
+turbulence amplitude $\delta z_\lambda$) and linear Landau damping (whose
+efficiency is independent of $\delta z_\lambda$), describing in detail how they
+affect and are affected by intermittency. The overall efficiency of linear
+Landau damping is not affected by intermittency in critically balanced
+turbulence, while stochastic heating is much more efficient in the presence of
+intermittent turbulence. Moreover, stochastic heating leads to a drop in the
+scale-dependent kurtosis over a narrow range of scales around the ion
+gyroscale.",1807.09301v2
+2018-07-31,Input-to-State Stability of a Clamped-Free Damped String in the Presence of Distributed and Boundary Disturbances,"This note establishes the Exponential Input-to-State Stability (EISS)
+property for a clamped-free damped string with respect to distributed and
+boundary disturbances. While efficient methods for establishing ISS properties
+for distributed parameter systems with respect to distributed disturbances have
+been developed during the last decades, establishing ISS properties with
+respect to boundary disturbances remains challenging. One of the well-known
+methods for well-posedness analysis of systems with boundary inputs is the use
+of a lifting operator for transferring the boundary disturbance to a
+distributed one. However, the resulting distributed disturbance involves time
+derivatives of the boundary perturbation. Thus, the subsequent ISS estimate
+depends on its amplitude, and may not be expressed in the strict form of ISS
+properties. To solve this problem, we show for a clamped-free damped string
+equation that the projection of the original system trajectories in an adequate
+Riesz basis can be used to establish the desired EISS property.",1807.11696v2
+2018-07-31,Spin absorption at ferromagnetic-metal/platinum-oxide interface,"We investigate the absorption of a spin current at a
+ferromagnetic-metal/Pt-oxide interface by measuring current-induced
+ferromagnetic resonance. The spin absorption was characterized by the magnetic
+damping of the heterostructure. We show that the magnetic damping of a
+Ni$_{81}$Fe$_{19}$ film is clearly enhanced by attaching Pt-oxide on the
+Ni$_{81}$Fe$_{19}$ film. The damping enhancement is disappeared by inserting an
+ultrathin Cu layer between the Ni$_{81}$Fe$_{19}$ and Pt-oxide layers. These
+results demonstrate an essential role of the direct contact between the
+Ni$_{81}$Fe$_{19}$ and Pt-oxide to induce sizable interface spin-orbit
+coupling. Furthermore, the spin-absorption parameter of the
+Ni$_{81}$Fe$_{19}$/Pt-oxide interface is comparable to that of intensively
+studied heterostructures with strong spin-orbit coupling, such as an oxide
+interface, topological insulators, metallic junctions with Rashba spin-orbit
+coupling. This result illustrates strong spin-orbit coupling at the
+ferromagnetic-metal/Pt-oxide interface, providing an important piece of
+information for quantitative understanding the spin absorption and spin-charge
+conversion at the ferromagnetic-metal/metallic-oxide interface.",1807.11806v1
+2018-08-16,Stability analysis of dissipative systems subject to nonlinear damping via Lyapunov techniques,"In this article, we provide a general strategy based on Lyapunov functionals
+to analyse global asymptotic stability of linear infinite-dimensional systems
+subject to nonlinear dampings under the assumption that the origin of the
+system is globally asymp-totically stable with a linear damping. To do so, we
+first characterize, in terms of Lyapunov functionals, several types of
+asymptotic stability for linear infinite-dimensional systems, namely the
+exponential and the polynomial stability. Then, we derive a Lyapunov functional
+for the nonlinear system, which is the sum of a Lyapunov functional coming from
+the linear system and another term with compensates the nonlinearity. Our
+results are then applied to the linearized Korteweg-de Vries equation and some
+wave equations.",1808.05370v1
+2018-09-05,On the forced Euler and Navier-Stokes equations: Linear damping and modified scattering,"We study the asymptotic behavior of the forced linear Euler and nonlinear
+Navier-Stokes equations close to Couette flow in a periodic channel. As our
+main result we show that for smooth time-periodic forcing linear inviscid
+damping persists, i.e. the velocity field (weakly) asymptotically converges.
+However, stability and scattering to the transport problem fail in $H^{s},
+s>-1$. We further show that this behavior is consistent with the nonlinear
+Euler equations and that a similar result also holds for the nonlinear
+Navier-Stokes equations. Hence, these results provide an indication that
+nonlinear inviscid damping may still hold in Sobolev regularity in the above
+sense despite the Gevrey regularity instability results of [Deng-Masmoudi
+2018].",1809.01729v1
+2018-09-12,Theory of bifurcation amplifiers utilizing the nonlinear dynamical response of an optically damped mechanical oscillator,"We consider a standard optomechanical system where a mechanical oscillator is
+coupled to a cavity mode through the radiation pressure interaction. The
+oscillator is coherently driven at its resonance frequency, whereas the cavity
+mode is driven below its resonance, providing optical damping of the mechanical
+oscillations. We study the nonlinear coherent response of the mechanical
+oscillator in this setup. For large mechanical amplitudes, we find that the
+system can display dynamical multistability if the optomechanical cooperativity
+exceeds a critical value. This analysis relates standard optomechanical damping
+to the dynamical attractors known from the theory of optomechanical
+self-sustained oscillations. We also investigate the effect of thermal and
+quantum noise and estimate the noise-induced switching rate between the stable
+states of the system. We then consider applications of this system and
+primarily focus on how it can be used as bifurcation amplifiers for the
+detection of small mechanical or optical signals. Finally, we show that in a
+related but more complicated setup featuring resonant optomechanical
+interactions, the same effects can be realized with a relaxed requirement on
+the size of the mechanical oscillations.",1809.04592v2
+2018-09-13,Second order asymptotical regularization methods for inverse problems in partial differential equations,"We develop Second Order Asymptotical Regularization (SOAR) methods for
+solving inverse source problems in elliptic partial differential equations with
+both Dirichlet and Neumann boundary data. We show the convergence results of
+SOAR with the fixed damping parameter, as well as with a dynamic damping
+parameter, which is a continuous analog of Nesterov's acceleration method.
+Moreover, by using Morozov's discrepancy principle together with a newly
+developed total energy discrepancy principle, we prove that the approximate
+solution of SOAR weakly converges to an exact source function as the
+measurement noise goes to zero. A damped symplectic scheme, combined with the
+finite element method, is developed for the numerical implementation of SOAR,
+which yields a novel iterative regularization scheme for solving inverse source
+problems. Several numerical examples are given to show the accuracy and the
+acceleration effect of SOAR. A comparison with the state-of-the-art methods is
+also provided.",1809.04971v2
+2018-09-24,Oscillation Damping Control of Pendulum-like Manipulation Platform using Moving Masses,"This paper presents an approach to damp out the oscillatory motion of the
+pendulum-like hanging platform on which a robotic manipulator is mounted. To
+this end, moving masses were installed on top of the platform. In this paper,
+asymptotic stability of the platform (which implies oscillation damping) is
+achieved by designing reference acceleration of the moving masses properly. A
+main feature of this work is that we can achieve asymptotic stability of not
+only the platform, but also the moving masses, which may be challenging due to
+the under-actuation nature. The proposed scheme is validated by the simulation
+studies.",1809.08819v1
+2018-07-16,A unified N-SECE strategy for highly coupled piezoelectric energy scavengers,"This paper proposes a novel vibration energy harvesting strategy based on an
+extension of the Synchronous Electric Charge Extraction (SECE) approach,
+enabling both the maximization of the harvested power and a consequent
+bandwidth enlargement in the case of highly coupled/lightly damped
+piezoelectric energy harvesters. The proposed strategy relies on the tuning of
+the frequency of the energy extraction events, which is either N times greater
+than the vibration frequency (Multiple SECE case, N > 1) or 1/N times smaller
+(Regenerative SECE, N < 1). We first prove analytically than increasing or
+decreasing N both lead to a damping reduction. While N has no impact on the
+system's resonance frequency in the Regenerative case (N < 1), we show that
+this resonant frequency becomes a function of N in the Multiple SECE case (N >
+1). Experimental results on a highly coupled/lowly damped piezoelectric
+harvester (k^2= 0.44, Q_m = 20) demonstrates the potential of this strategy,
+leading to 257% harvested power improvement compared to SECE (N = 1). and the
+possibility to tune the resonant frequency on a range as large as 35% of the
+short-circuit resonant frequency of the harvester.",1809.09685v1
+2018-10-09,The lifespan of solutions of semilinear wave equations with the scale-invariant damping in one space dimension,"The critical constant of time-decaying damping in the scale-invariant case is
+recently conjectured. It also has been expected that the lifespan estimate is
+the same as for the associated semilinear heat equations if the constant is in
+the \heat-like"" domain. In this paper, we point out that this is not true if
+the total integral of the sum of initial position and speed vanishes. In such a
+case, we have a new type of the lifespan estimates which is closely related to
+the non-damped case in shifted space dimensions.",1810.03780v2
+2018-10-24,Justification of the Lugiato-Lefever model from a damped driven $φ^4$ equation,"The Lugiato-Lefever equation is a damped and driven version of the well-known
+nonlinear Schr\""odinger equation. It is a mathematical model describing complex
+phenomena in dissipative and nonlinear optical cavities. Within the last two
+decades, the equation has gained a wide attention as it becomes the basic model
+describing optical frequency combs. Recent works derive the Lugiato-Lefever
+equation from a class of damped driven $\phi^4$ equations closed to resonance.
+In this paper, we provide a justification of the envelope approximation. From
+the analysis point of view, the result is novel and non-trivial as the drive
+yields a perturbation term that is not square integrable. The main approach
+proposed in this work is to decompose the solutions into a combination of the
+background and the integrable component. This paper is the first part of a
+two-manuscript series.",1810.10630v1
+2018-11-06,Decay properties and asymptotic profiles for elastic waves with Kelvin-Voigt damping in 2D,"In this paper we consider elastic waves with Kelvin-Voigt damping in 2D. For
+the linear problem, applying pointwise estimates of the partial Fourier
+transform of solutions in the Fourier space and asymptotic expansions of
+eigenvalues and their eigenprojections, we obtain sharp energy decay estimates
+with additional $L^m$ regularity and $L^p-L^q$ estimates on the conjugate line.
+Furthermore, we derive asymptotic profiles of solutions under different
+assumptions of initial data. For the semilinear problem, we use the derived
+$L^2-L^2$ estimates with additional $L^m$ regularity to prove global (in time)
+existence of small data solutions to the weakly coupled system. Finally, to
+deal with elastic waves with Kelvin-Voigt damping in 3D, we apply the Helmholtz
+decomposition.",1811.02223v3
+2018-12-06,Damping and Anti-Damping Phenomena in Metallic Antiferromagnets: An ab-initio Study,"We report on a first principles study of anti-ferromagnetic resonance (AFMR)
+phenomena in metallic systems [MnX (X=Ir,Pt,Pd,Rh) and FeRh] under an external
+electric field. We demonstrate that the AFMR linewidth can be separated into a
+relativistic component originating from the angular momentum transfer between
+the collinear AFM subsystem and the crystal through the spin orbit coupling
+(SOC), and an exchange component that originates from the spin exchange between
+the two sublattices. The calculations reveal that the latter component becomes
+significant in the low temperature regime. Furthermore, we present results for
+the current-induced intersublattice torque which can be separated into the
+Field-Like (FL) and Damping-Like (DL) components, affecting the intersublattice
+exchange coupling and AFMR linewidth, respectively.",1812.02844v2
+2018-12-12,Extreme wave events for a nonlinear Schrödinger equation with linear damping and Gaussian driving,"We perform a numerical study of the initial-boundary value problem, with
+vanishing boundary conditions, of a driven nonlinear Schr\""odinger equation
+(NLS) with linear damping and a Gaussian driver. We identify Peregrine-like
+rogue waveforms, excited by two different types of vanishing initial data
+decaying at an algebraic or exponential rate. The observed extreme events
+emerge on top of a decaying support. Depending on the spatial/temporal scales
+of the driver, the transient dynamics -- prior to the eventual decay of the
+solutions -- may resemble the one in the semiclassical limit of the integrable
+NLS, or may, e.g., lead to large-amplitude breather-like patterns. The effects
+of the damping strength and driving amplitude, in suppressing or enhancing
+respectively the relevant features, as well as of the phase of the driver in
+the construction of a diverse array of spatiotemporal patterns, are numerically
+analyzed.",1812.05439v3
+2018-12-13,Stability of elastic transmission systems with a local Kelvin-Voigt damping,"In this paper, we consider the longitudinal and transversal vibrations of the
+transmission Euler-Bernoulli beam with Kelvin-Voigt damping distributed locally
+on any subinterval of the region occupied by the beam and only in one side of
+the transmission point. We prove that the semigroup associated with the
+equation for the transversal motion of the beam is exponentially stable,
+although the semigroup associated with the equation for the longitudinal motion
+of the beam is polynomially stable. Due to the locally distributed and
+unbounded nature of the damping, we use a frequency domain method and combine a
+contradiction argument with the multiplier technique to carry out a special
+analysis for the resolvent.",1812.05923v1
+2018-12-13,Energy decay estimates of elastic transmission wave/beam systems with a local Kelvin-Voigt damping,"We consider a beam and a wave equations coupled on an elastic beam through
+transmission conditions. The damping which is locally distributed acts through
+one of the two equations only; its effect is transmitted to the other equation
+through the coupling. First we consider the case where the dissipation acts
+through the beam equation. Using a recent result of Borichev and Tomilov on
+polynomial decay characterization of bounded semigroups we provide a precise
+decay estimates showing that the energy of this coupled system decays
+polynomially as the time variable goes to infinity. Second, we discuss the case
+where the damping acts through the wave equation. Proceeding as in the first
+case, we prove that this system is also polynomially stable and we provide
+precise polynomial decay estimates for its energy. Finally, we show the lack of
+uniform exponential decay of solutions for both models.",1812.05924v1
+2018-12-20,Sound attenuation in stable glasses,"Understanding the difference between universal low-temperature properties of
+amorphous and crystalline solids requires an explanation of the stronger
+damping of long-wavelength phonons in amorphous solids. A longstanding sound
+attenuation scenario, resulting from a combination of experiments, theories,
+and simulations, leads to a quartic scaling of sound attenuation with the
+wavevector, which is commonly attributed to Rayleigh scattering of the sound.
+Modern computer simulations offer conflicting conclusions regarding the
+validity of this picture. We simulate glasses with an unprecedentedly broad
+range of stabilities to perform the first microscopic analysis of sound damping
+in model glass formers across a range of experimentally relevant preparation
+protocols. We present a convincing evidence that quartic scaling is recovered
+for small wavevectors irrespective of the glass's stability. With increasing
+stability, the wavevector where the quartic scaling begins increases by
+approximately a factor of three and the sound attenuation decreases by over an
+order of magnitude. Our results uncover an intimate connection between glass
+stability and sound damping.",1812.08736v2
+2018-12-21,"Reply to the Comment on ""Negative Landau damping in bilayer graphene""","Here we address the concerns of Svintsov and Ryzhii [arXiv:1812.03764] on our
+article on negative Landau damping in graphene [Phys. Rev. Lett. 119, 133901
+(2017)]. We prove that due to the differences between the kinetic and canonical
+momenta, the conductivity of drift-current biased graphene is ruled by a
+Galilean transformation when the electron-electron interactions predominate and
+force the electron gas to move with constant velocity, similar to a moving
+medium. Furthermore, it is shown that the nonlocal effects in graphene neither
+preclude a negative Landau damping nor the emergence of instabilities in
+graphene platforms.",1812.09103v3
+2018-12-27,Nonexistence of global solutions for a weakly coupled system of semilinear damped wave equations of derivative type in the scattering case,"In this paper we consider the blow-up for solutions to a weakly coupled
+system of semilinear damped wave equations of derivative type in the scattering
+case. After introducing suitable functionals proposed by Lai-Takamura for the
+corresponding single semilinear equation, we employ Kato's lemma to derive the
+blow-up result in the subcritical case. On the other hand, in the critical case
+an iteration procedure based on the slicing method is employed. Let us point
+out that we find as critical curve in the p-q plane for the pair of exponents
+(p, q) in the nonlinear terms the same one as for the weakly coupled system of
+semilinear not-damped wave equations with the same kind of nonlinearities.",1812.10653v1
+2018-12-30,"Smooth, Time-invariant Regulation of Nonholonomic Systems via Energy Pumping-and-Damping","In this paper we propose an energy pumping-and-damping technique to regulate
+nonholonomic systems described by kinematic models. The controller design
+follows the widely popular interconnection and damping assignment
+passivity-based methodology, with the free matrices partially structured. Two
+asymptotic regulation objectives are considered: drive to zero the state or
+drive the systems total energy to a desired constant value. In both cases, the
+control laws are smooth, time-invariant, state-feedbacks. For the nonholonomic
+integrator we give an almost global solution for both problems, with the
+objectives ensured for all system initial conditions starting outside a set
+that has zero Lebesgue measure and is nowhere dense. For the general case of
+higher-order nonholonomic systems in chained form, a local stability result is
+given. Simulation results comparing the performance of the proposed controller
+with other existing designs are also provided.",1812.11538v2
+2019-01-05,Simulations of wobble damping in viscoelastic rotators,"Using a damped mass-spring model, we simulate wobble of spinning homogeneous
+viscoelastic ellipsoids undergoing non-principal axis rotation. Energy damping
+rates are measured for oblate and prolate bodies with different spin rates,
+spin states, viscoelastic relaxation timescales, axis ratios, and strengths.
+Analytical models using a quality factor by Breiter et al. (2012) and for the
+Maxwell rheology by Frouard & Efroimsky (2018) match our numerical measurements
+of the energy dissipation rate after we modify their predictions for the
+numerically simulated Kelvin-Voigt rheology. Simulations of nearly spherical
+but wobbling bodies with hard and soft cores show that the energy dissipation
+rate is more sensitive to the material properties in the core than near the
+surface. The sensitivity to viscoelastic model implies that inferred statistics
+of tumbling lifetimes in asteroids might be interpreted in terms of differences
+in their material properties.",1901.01439v3
+2019-01-16,"Laboratory investigations of the bending rheology of floating saline ice, and physical mechanisms of wave damping, in the HSVA ice tank","An experiment on the propagation of flexural-gravity waves was performed in
+the HSVA ice tank. Physical characteristics of the water-ice system were
+measured in different locations in the tank during the tests, with a number of
+sensors deployed in the water, on the ice and in the air. Water velocity was
+measured with an acoustic doppler velocimeter (ADV) and an acoustic doppler
+current profiler (ADCP); wave amplitudes were measured with ultrasonic sensors
+and the optical system Qualisys; in-plane deformations of the ice and the
+temperature of the ice and water were measured by fiber optic sensors, and
+acoustic emissions were recorded with compressional crystal sensors. All
+together 61 tests were performed, with ice thicknesses of 3 cm and 5 cm. The
+experimental setup and selected results of the tests are discussed in this
+paper. We show that cyclic motion of the ice along the tank, imitating ice
+drift, causes an increase in wave damping. We also show that the formation of
+non-through cracks in the ice, caused by the action of waves, increases wave
+damping.",1901.05333v1
+2019-01-24,Generalized framework for testing gravity with gravitational-wave propagation. III. Future prospect,"The properties of gravitational-wave (GW) propagation are modified in
+alternative theories of gravity and are crucial observables to test gravity at
+cosmological distance. The propagation speed has already been measured from
+GW170817 so precisely and pinned down to the speed of light, while other
+properties of GW propagation have not constrained tightly yet. In this paper,
+we investigate the measurement precisions of the amplitude damping rate
+(equivalently, the time variation of the gravitational coupling for GWs) and
+graviton mass in the generalized framework of GW propagation with the future
+detectors such as Voyager, Cosmic Explorer, and Einstein Telescope. As a
+result, we show that the future GW observation can reach 1% error for the
+amplitude damping. We also study the time variation of the gravitational
+couplings in Horndeski theory by performing Monte Carlo-based numerical
+simulations. From the simulation results, we find that the current accelerating
+Universe prefers the models with less damping of GWs and that the equivalence
+principle can be tested at the level of 1% by the future GW observation.",1901.08249v2
+2019-01-31,Perturbed Markov Chains and Information Networks,"The paper is devoted to studies of perturbed Markov chains commonly used for
+description of information networks. In such models, the matrix of transition
+probabilities for the corresponding Markov chain is usually regularised by
+adding a special damping matrix multiplied by a small damping (perturbation)
+parameter $\varepsilon$. We give effective upper bounds for the rate of
+approximation for stationary distributions of unperturbed Markov chains by
+stationary distributions of perturbed Markov chains with regularised matrices
+of transition probabilities, asymptotic expansions for approximating stationary
+distributions with respect to damping parameter, as well as explicit upper
+bounds for the rate of convergence in ergodic theorems for $n$-step transition
+probabilities in triangular array mode, where perturbation parameter
+$\varepsilon \to 0$ and $n \to \infty$, simultaneously. The results of
+numerical experiments are also presented",1901.11483v3
+2019-02-14,Dynamic Interconnection and Damping Injection for Input-to-State Stable Bilateral Teleoperation,"In bilateral teleoperation, the human who operates the master and the
+environment which interacts with the slave are part of the force feedback loop.
+Yet, both have time-varying and unpredictable dynamics and are challenging to
+model. A conventional strategy for sidestepping the demand for their models in
+the stability analysis is to assume passive user and environment, and to
+control the master-communications-slave system to be passive as well. This
+paper circumvents the need to model the user and environment in a novel way: it
+regards their forces as external excitations for a semi-autonomous force
+feedback loop, which it outfits with a dynamic interconnection and damping
+injection controller that renders bilateral teleoperation with time-varying
+delays exponentially input-to-state stable. The controller uses the position
+and velocity measurements of the local robot and the delayed position
+transmitted from the other robot to robustly synchronize the master and slave
+under the user and environment perturbations. Lyapunov-Krasovskii stability
+analysis shows that the proposed strategy (i) can confine the position error
+between the master and slave to an invariant set, and (ii) can drive it
+exponentially to a globally attractive set. Thus, the dynamic interconnection
+and damping injection approach has practical relevance for telemanipulation
+tasks with given precision requirements.",1902.05500v1
+2019-02-15,Evidence for Electron Landau Damping in Space Plasma Turbulence,"How turbulent energy is dissipated in weakly collisional space and
+astrophysical plasmas is a major open question. Here, we present the
+application of a field-particle correlation technique to directly measure the
+transfer of energy between the turbulent electromagnetic field and electrons in
+the Earth's magnetosheath, the region of solar wind downstream of the Earth's
+bow shock. The measurement of the secular energy transfer from the parallel
+electric field as a function of electron velocity shows a signature consistent
+with Landau damping. This signature is coherent over time, close to the
+predicted resonant velocity, similar to that seen in kinetic Alfv\'en
+turbulence simulations, and disappears under phase randomisation. This suggests
+that electron Landau damping could play a significant role in turbulent plasma
+heating, and that the technique is a valuable tool for determining the particle
+energisation processes operating in space and astrophysical plasmas.",1902.05785v1
+2019-02-22,Thermal induced monochromatic microwave generation in magnon-polariton,"We propose thermal induced generation of monochromatic microwave radiation in
+magnon-polariton. Mechanism of thermal to microwave energy transformation is
+based on intrinsic energy loss compensation of coupled magnon and microwave
+cavity oscillators by thermal induced ""negative damping"". A singularity at an
+exceptional point is achieved when at the critical value of ""negative damping""
+the damping of the system is fully compensated. At the exceptional point, the
+input energy is equally distributed between the magnon and photon subsystems of
+the magnon-polariton. The efficiency of transformation of thermal energy into
+useful microwave radiation is estimated to be as large as 17 percent due to
+magnon-photon coupling mediated direct conversation of spin current into
+microwave photons.",1902.08383v1
+2019-03-04,Nonlinear inviscid damping for zero mean perturbation of the 2D Euler Couette flow,"In this note we revisit the proof of Bedrossian and Masmoudi
+[arXiv:1306.5028] about the inviscid damping of planar shear flows in the 2D
+Euler equations under the assumption of zero mean perturbation. We prove that a
+small perturbation to the 2D Euler Couette flow in $\mathbb{T}\times
+\mathbb{R}$ strongly converge to zero, under the additional assumption that the
+average in $x$ is always zero. In general the mean is not a conserved quantity
+for the nonlinear dynamics, for this reason this is a particular case.
+Nevertheless our assumption allow the presence of echoes in the problem, which
+we control by an approximation of the weight built in [arXiv:1306.5028]. The
+aim of this note is to present the mathematical techniques used in
+[arXiv:1306.5028] and can be useful as a first approach to the nonlinear
+inviscid damping.",1903.01543v1
+2019-03-10,Orbital stabilization of nonlinear systems via Mexican sombrero energy shaping and pumping-and-damping injection,"In this paper we show that a slight modification to the widely popular
+interconnection and damping assignment passivity-based control
+method---originally proposed for stabilization of equilibria of nonlinear
+systems---allows us to provide a solution to the more challenging orbital
+stabilization problem. Two different, though related, ways how this procedure
+can be applied are proposed. First, the assignment of an energy function that
+has a minimum in a closed curve, i.e., with the shape of a Mexican sombrero.
+Second, the use of a damping matrix that changes ""sign"" according to the
+position of the state trajectory relative to the desired orbit, that is,
+pumping or dissipating energy. The proposed methodologies are illustrated with
+the example of the induction motor and prove that it yields the industry
+standard field oriented control.",1903.04070v3
+2019-03-11,Impact of thermal effects on the evolution of eccentricity and inclination of low-mass planets,"Using linear perturbation theory, we evaluate the time-dependent force
+exerted on an eccentric and inclined low-mass planet embedded in a gaseous
+protoplanetary disc with finite thermal diffusivity $\chi$. We assume the
+eccentricity and inclination to be small compared to the size of the thermal
+lobes $\lambda\sim(\chi/\Omega)^{1/2}$, itself generally much smaller than the
+scalelength of pressure $H$. When the planet is non-luminous, we find that its
+eccentricity and inclination are vigorously damped by the disc, over a
+timescale shorter by a factor $H/\lambda$ than the damping timescale in
+adiabatic discs. On the contrary, when the luminosity-to-mass ratio of the
+planet exceeds a threshold that depends on the disc's properties, its
+eccentricity and inclination undergo an exponential growth. In the limit of a
+large luminosity, the growth rate of the eccentricity is 2.5~times larger than
+that of the inclination, in agreement with previous numerical work. Depending
+on their luminosity, planetary embryos therefore exhibit much more diverse
+behaviours than the mild damping of eccentricity and inclination considered
+hitherto.",1903.04470v2
+2019-03-14,The Strichartz estimates for the damped wave equation and the behavior of solutions for the energy critical nonlinear equation,"For the linear damped wave equation (DW), the $L^p$-$L^q$ type estimates have
+been well studied. Recently, Watanabe showed the Strichartz estimates for DW
+when $d=2,3$. In the present paper, we give Strichartz estimates for DW in
+higher dimensions. Moreover, by applying the estimates, we give the local
+well-posedness of the energy critical nonlinear damped wave equation (NLDW)
+$\partial_t^2 u - \Delta u +\partial_t u = |u|^{\frac{4}{d-2}}u$, $(t,x) \in
+[0,T) \times \mathbb{R}^d$, where $3 \leq d \leq 5$. Especially, we show the
+small data global existence for NLDW. In addition, we investigate the behavior
+of the solutions to NLDW. Namely, we give a decay result for solutions with
+finite Strichartz norm and a blow-up result for solutions with negative Nehari
+functional.",1903.05887v1
+2019-04-17,Decays for Kelvin-Voigt damped wave equations I : the black box perturbative method,"We show in this article how perturbative approaches~from our work with Hitrik
+(see also the work by Anantharaman-Macia) and the {\em black box} strategy
+from~ our work with Zworski allow to obtain decay rates for Kelvin-Voigt damped
+wave equations from quite standard resolvent estimates : Carleman estimates or
+geometric control estimates for Helmoltz equationCarleman or other resolvent
+estimates for the Helmoltz equation. Though in this context of Kelvin Voigt
+damping, such approach is unlikely to allow for the optimal results when
+additional geometric assumptions are considered (see \cite{BuCh, Bu19}), it
+turns out that using this method, we can obtain the usual logarithmic decay
+which is optimal in general cases. We also present some applications of this
+approach giving decay rates in some particular geometries (tori).",1904.08318v2
+2019-04-17,Non-Hermitian skin effect and chiral damping in open quantum systems,"One of the unique features of non-Hermitian Hamiltonians is the non-Hermitian
+skin effect, namely that the eigenstates are exponentially localized at the
+boundary of the system. For open quantum systems, a short-time evolution can
+often be well described by the effective non-Hermitian Hamiltonians, while
+long-time dynamics calls for the Lindblad master equations, in which the
+Liouvillian superoperators generate time evolution. In this Letter, we find
+that Liouvillian superoperators can exhibit the non-Hermitian skin effect, and
+uncover its unexpected physical consequences. It is shown that the
+non-Hermitian skin effect dramatically shapes the long-time dynamics, such that
+the damping in a class of open quantum systems is algebraic under periodic
+boundary condition but exponential under open boundary condition. Moreover, the
+non-Hermitian skin effect and non-Bloch bands cause a chiral damping with a
+sharp wavefront. These phenomena are beyond the effective non-Hermitian
+Hamiltonians; instead, they belong to the non-Hermitian physics of full-fledged
+open quantum dynamics.",1904.08432v2
+2019-04-19,Plasmon-Emitter Interactions at the Nanoscale,"Plasmon-emitter interactions are of paramount importance in modern
+nanoplasmonics and are generally maximal at short emitter-surface separations.
+However, when the separation falls below 10-20 nm, the classical theory
+progressively deteriorates due to its neglect of quantum mechanical effects
+such as nonlocality, electronic spill-out, and Landau damping. Here, we show
+how this neglect can be remedied by presenting a unified theoretical treatment
+of mesoscopic electrodynamics grounded on the framework of Feibelman
+$d$-parameters. Crucially, our technique naturally incorporates nonclassical
+resonance shifts and surface-enabled Landau damping - a nonlocal damping effect
+- which have a dramatic impact on the amplitude and spectral distribution of
+plasmon-emitter interactions. We consider a broad array of plasmon-emitter
+interactions ranging from dipolar and multipolar spontaneous emission
+enhancement, to plasmon-assisted energy transfer and enhancement of two-photon
+transitions. The formalism presented here gives a complete account of both
+plasmons and plasmon-emitter interactions at the nanoscale, constituting a
+simple yet rigorous and general platform to incorporate nonclassical effects in
+plasmon-empowered nanophotonic phenomena.",1904.09279v1
+2019-04-23,Ultrafast depinning of domain wall in notched antiferromagnetic nanostructures,"The pinning and depinning of antiferromagnetic (AFM) domain wall is certainly
+the core issue of AFM spintronics. In this work, we study theoretically the
+N\'eel-type domain wall pinning and depinning at a notch in an
+antiferromagnetic (AFM) nano-ribbon. The depinning field depending on the notch
+dimension and intrinsic physical parameters are deduced and also numerically
+calculated. Contrary to conventional conception, it is revealed that the
+depinning field is remarkably dependent of the damping constant and the
+time-dependent oscillation of the domain wall position in the weakly damping
+regime benefits to the wall depinning, resulting in a gradual increase of the
+depinning field up to a saturation value with increasing damping constant. A
+one-dimensional model accounting of the internal dynamics of domain wall is
+used to explain perfectly the simulated results. It is demonstrated that the
+depinning mechanism of an AFM domain wall differs from ferromagnetic domain
+wall by exhibiting a depinning speed typically three orders of magnitude faster
+than the latter, suggesting the ultrafast dynamics of an AFM system.",1904.10197v2
+2019-05-08,Discrete Energy behavior of a damped Timoshenko system,"In this article, we consider a one-dimensional Timoshenko system subject to
+different types of dissipation (linear and nonlinear dampings). Based on a
+combination between the finite element and the finite difference methods, we
+design a discretization scheme for the different Timoshenko systems under
+consideration. We first come up with a numerical scheme to the free-undamped
+Timoshenko system. Then, we adapt this numerical scheme to the corresponding
+linear and nonlinear damped systems. Interestingly, this scheme reaches to
+reproduce the most important properties of the discrete energy. Namely, we show
+for the discrete energy the positivity, the energy conservation property and
+the different decay rate profiles. We numerically reproduce the known
+analytical results established on the decay rate of the energy associated with
+each type of dissipation.",1905.03050v1
+2019-05-08,Attractors for semilinear wave equations with localized damping and external forces,"This paper is concerned with long-time dynamics of semilinear wave equations
+defined on bounded domains of $\mathbb{R}^3$ with cubic nonlinear terms and
+locally distributed damping. The existence of regular finite-dimensional global
+attractors established by Chueshov, Lasiecka and Toundykov (2008) reflects a
+good deal of the current state of the art on this matter. Our contribution is
+threefold. First, we prove uniform boundedness of attractors with respect to a
+forcing parameter. Then, we study the continuity of attractors with respect to
+the parameter in a residual dense set. Finally, we show the existence of
+generalized exponential attractors. These aspects were not previously
+considered for wave equations with localized damping.",1905.03285v1
+2019-05-16,Global attractors and their upper semicontinuity for a structural damped wave equation with supercritical nonlinearity on $\mathbb{R}^{N}$,"The paper investigates the existence of global attractors and their upper
+semicontinuity for a structural damped wave equation on $\mathbb{R}^{N}:
+u_{tt}-\Delta u+(-\Delta)^\alpha u_{t}+u_{t}+u+g(u)=f(x)$, where $\alpha\in
+(1/2, 1)$ is called a dissipative index. We propose a new method based on the
+harmonic analysis technique and the commutator estimate to exploit the
+dissipative effect of the structural damping $(-\Delta)^\alpha u_{t}$ and to
+overcome the essential difficulty: ""both the unbounded domain $\mathbb{R}^N$
+and the supercritical nonlinearity cause that the Sobolev embedding loses its
+compactness""; Meanwhile we show that there exists a supercritical index
+$p_\alpha\equiv\frac{N+4\alpha}{N-4\alpha}$ depending on $\alpha$ such that
+when the growth exponent $p$ of the nonlinearity $g(u)$ is up to the
+supercritical range: $1\leqslant p<p_\alpha$: (i) the IVP of the equation is
+well-posed and its solution is of additionally global smoothness when $t>0$;
+(ii) the related solution semigroup possesses a global attractor
+$\mathcal{A}_\alpha$ in natural energy space for each $\alpha\in (1/2, 1)$;
+(iii) the family of global attractors $\{\mathcal{A}_\alpha\}_{\alpha\in (1/2,
+1) }$ is upper semicontinuous at each point $\alpha_0\in (1/2, 1)$.",1905.06778v1
+2019-05-20,Quantum parameter-estimation of frequency and damping of a harmonic-oscillator,"We determine the quantum Cram\'er-Rao bound for the precision with which the
+oscillator frequency and damping constant of a damped quantum harmonic
+oscillator in an arbitrary Gaussian state can be estimated. This goes beyond
+standard quantum parameter estimation of a single mode Gaussian state for which
+typically a mode of fixed frequency is assumed. We present a scheme through
+which the frequency estimation can nevertheless be based on the known results
+for single-mode quantum parameter estimation with Gaussian states. Based on
+these results, we investigate the optimal measurement time. For measuring the
+oscillator frequency, our results unify previously known partial results and
+constitute an explicit solution for a general single-mode Gaussian state.
+Furthermore, we show that with existing carbon nanotube resonators (see J.
+Chaste et al.~Nature Nanotechnology 7, 301 (2012)) it should be possible to
+achieve a mass sensitivity of the order of an electron mass $\text{Hz}^{-1/2}$.",1905.08288v1
+2019-05-24,Damped oscillations of the probability of random events followed by absolute refractory period: exact analytical results,"There are numerous examples of natural and artificial processes that
+represent stochastic sequences of events followed by an absolute refractory
+period during which the occurrence of a subsequent event is impossible. In the
+simplest case of a generalized Bernoulli scheme for uniform random events
+followed by the absolute refractory period, the event probability as a function
+of time can exhibit damped transient oscillations. Using stochastically-spiking
+point neuron as a model example, we present an exact and compact analytical
+description for the oscillations without invoking the standard renewal theory.
+The resulting formulas stand out for their relative simplicity, allowing one to
+analytically obtain the amplitude damping of the 2nd and 3rd peaks of the event
+probability.",1905.10172v3
+2019-06-11,Study of semi-linear $σ$-evolution equations with frictional and visco-elastic damping,"In this article, we study semi-linear $\sigma$-evolution equations with
+double damping including frictional and visco-elastic damping for any
+$\sigma\ge 1$. We are interested in investigating not only higher order
+asymptotic expansions of solutions but also diffusion phenomenon in the
+$L^p-L^q$ framework, with $1\le p\le q\le \infty$, to the corresponding linear
+equations. By assuming additional $L^{m}$ regularity on the initial data, with
+$m\in [1,2)$, we prove the global (in time) existence of small data energy
+solutions and indicate the large time behavior of the global obtained solutions
+as well to semi-linear equations. Moreover, we also determine the so-called
+critical exponent when $\sigma$ is integers.",1906.04471v1
+2019-07-08,Damping of density oscillations in neutrino-transparent nuclear matter,"We calculate the bulk-viscous dissipation time for adiabatic density
+oscillations in nuclear matter at densities of 1-7 times nuclear saturation
+density and at temperatures ranging from 1 MeV, where corrections to previous
+low-temperature calculations become important, up to 10 MeV, where the
+assumption of neutrino transparency is no longer valid. Under these conditions,
+which are expected to occur in neutron star mergers, damping of density
+oscillations arises from beta equilibration via weak interactions. We find that
+for 1 kHz oscillations the shortest dissipation times are in the 5 to 20 ms
+range, depending on the equation of state, which means that bulk viscous
+damping could affect the dynamics of a neutron star merger. For higher
+frequencies the dissipation time can be even shorter.",1907.03795v2
+2019-07-12,Decoherence of collective motion in warm nuclei,"Collective states in cold nuclei are represented by a wave function that
+assigns coherent phases to the participating nucleons. The degree of coherence
+decreases with excitation energy above the yrast line because of coupling to
+the increasingly dense background of quasiparticle excitations. The
+consequences of decoherence are discussed, starting with the well studied case
+of rotational damping. In addition to superdeformed bands, a highly excited
+oblate band is presented as a new example of screening from rotational damping.
+Suppression of pair correlation leads to incoherent thermal M1 radiation, which
+appears as an exponential spike (LEMAR) at zero energy in the $\gamma$ strength
+function of spherical nuclei. In deformed nuclei a Scissors Resonance appears
+and LEMAR changes to damped magnetic rotation, which is interpreted as partial
+restoration of coherence.",1907.05569v1
+2019-07-24,First-order optimization algorithms via inertial systems with Hessian driven damping,"In a Hilbert space setting, for convex optimization, we analyze the
+convergence rate of a class of first-order algorithms involving inertial
+features. They can be interpreted as discrete time versions of inertial
+dynamics involving both viscous and Hessian-driven dampings. The geometrical
+damping driven by the Hessian intervenes in the dynamics in the form $\nabla^2
+f (x(t)) \dot{x} (t)$. By treating this term as the time derivative of $ \nabla
+f (x (t)) $, this gives, in discretized form, first-order algorithms in time
+and space. In addition to the convergence properties attached to Nesterov-type
+accelerated gradient methods, the algorithms thus obtained are new and show a
+rapid convergence towards zero of the gradients. On the basis of a
+regularization technique using the Moreau envelope, we extend these methods to
+non-smooth convex functions with extended real values. The introduction of time
+scale factors makes it possible to further accelerate these algorithms. We also
+report numerical results on structured problems to support our theoretical
+findings.",1907.10536v2
+2019-07-26,L^p-asymptotic stability analysis of a 1D wave equation with a nonlinear damping,"This paper is concerned with the asymptotic stability analysis of a one
+dimensional wave equation with Dirichlet boundary conditions subject to a
+nonlinear distributed damping with an L p functional framework, p $\in$ [2,
+$\infty$]. Some well-posedness results are provided together with exponential
+decay to zero of trajectories, with an estimation of the decay rate. The
+well-posedness results are proved by considering an appropriate functional of
+the energy in the desired functional spaces introduced by Haraux in [11].
+Asymptotic behavior analysis is based on an attractivity result on a trajectory
+of an infinite-dimensional linear time-varying system with a special structure,
+which relies on the introduction of a suitable Lyapunov functional. Note that
+some of the results of this paper apply for a large class of nonmonotone
+dampings.",1907.11712v1
+2019-08-13,"A Gevrey class semigroup, exponential decay and Lack of analyticity for a system formed by a Kirchhoff-Love plate equation and the equation of a membrane-like electric network with indirect fractional damping","The emphasis in this paper is on the Coupled System of a Kirchhoff-Love Plate
+Equation with the Equation of a Membrane-like Electrical Network, where the
+coupling is of higher order given by the Laplacian of the displacement velocity
+$\gamma\Delta u_t$ and the Laplacian of the electric potential field
+$\gamma\Delta v_t $, here only one of the equations is conservative and the
+other has dissipative properties. The dissipative mechanism is given by an
+intermediate damping $(-\Delta)^\theta v_t$ between the electrical damping
+potential for $\theta=0$ and the Laplacian of the electric potential for
+$\theta=1$. We show that $S(t)=e^{\mathbb{B}t}$ is not analytic for
+$\theta\in[0, 1)$ and analytic for $\theta=1$, however $S(t)=e^{\mathbb{B}t}$
+decays exponentially for $0\leq \theta\leq 1$ and $S(t)$ is of Gevrey class $s>
+\frac{2+\theta}{\theta}$ when the parameter $\theta$ lies in the interval
+$(0,1)$.",1908.04826v3
+2019-08-20,Partial Optomechanical Refrigeration via Multimode Cold-Damping Feedback,"We provide a fully analytical treatment for the partial refrigeration of the
+thermal motion of a quantum mechanical resonator under the action of feedback.
+As opposed to standard cavity optomechanics where the aim is to isolate and
+cool a single mechanical mode, the aim here is to extract the thermal energy
+from many vibrational modes within a large frequency bandwidth. We consider a
+standard cold-damping technique where homodyne read-out of the cavity output
+field is fed into a feedback loop that provides a cooling action directly
+applied on the mechanical resonator. Analytical and numerical results predict
+that low final occupancies are achievable independently of the number of modes
+addressed by the feedback as long as the cooling rate is smaller than the
+intermode frequency separation. For resonators exhibiting a few nearly
+degenerate pairs of modes cooling is less efficient and a weak dependence on
+the number of modes is obtained. These scalings hint towards the design of
+frequency resolved mechanical resonators where efficient refrigeration is
+possible via simultaneous cold-damping feedback.",1908.07348v2
+2019-08-26,Description and classification of 2-solitary waves for nonlinear damped Klein-Gordon equations,"We describe completely 2-solitary waves related to the ground state of the
+nonlinear damped Klein-Gordon equation \begin{equation*}
+\partial_{tt}u+2\alpha\partial_{t}u-\Delta u+u-|u|^{p-1}u=0 \end{equation*} on
+$\bf R^N$, for $1\leq N\leq 5$ and energy subcritical exponents $p>2$. The
+description is twofold.
+  First, we prove that 2-solitary waves with same sign do not exist. Second, we
+construct and classify the full family of 2-solitary waves in the case of
+opposite signs. Close to the sum of two remote solitary waves, it turns out
+that only the components of the initial data in the unstable direction of each
+ground state are relevant in the large time asymptotic behavior of the
+solution. In particular, we show that $2$-solitary waves have a universal
+behavior: the distance between the solitary waves is asymptotic to $\log t$ as
+$t\to \infty$. This behavior is due to damping of the initial data combined
+with strong interactions between the solitary waves.",1908.09527v1
+2019-08-30,"Magnetization reversal, damping properties and magnetic anisotropy of L10-ordered FeNi thin films","L10 ordered magnetic alloys such as FePt, FePd, CoPt and FeNi are well known
+for their large magnetocrystalline anisotropy. Among these, L10-FeNi alloy is
+economically viable material for magnetic recording media because it does not
+contain rare earth and noble elements. In this work, L10-FeNi films with three
+different strengths of anisotropy were fabricated by varying the deposition
+process in molecular beam epitaxy system. We have investigated the
+magnetization reversal along with domain imaging via magneto optic Kerr effect
+based microscope. It is found that in all three samples, the magnetization
+reversal is happening via domain wall motion. Further ferromagnetic resonance
+(FMR) spectroscopy was performed to evaluate the damping constant and magnetic
+anisotropy. It was observed that the FeNi sample with moderate strength of
+anisotropy exhibits low value of damping constant ~ 4.9X10^-3. In addition to
+this, it was found that the films possess a mixture of cubic and uniaxial
+anisotropies.",1908.11761v1
+2019-09-24,DAMPE Excess from Leptophilic Vector Dark Matter: Model Independent Approach,"We study all extensions of the Standard Model (SM) with a vector dark matter
+(VDM) candidate which can explain the peak structure observed by recent DAMPE
+experiment in electron-positron cosmic ray spectrum. In this regard, we
+consider all leptophilic renormalizable VDM-SM interactions through scalar,
+spinor, and vector mediators. We show that only two out of six possible models
+could produce DAMPE signal by annihilation of VDM with the mass about 1.5 TeV
+in a nearby subhalo whilst simultaneously satisfying constraints from DM relic
+density, direct/indirect detection, and the collider bounds. These two models
+are the ones with scalar/pseudoscalar mediator $ \phi $ with $ M_{\phi} \in
+[1500,3000] $ GeV.",1909.10729v2
+2019-09-24,Evaluating the Impacts of Transmission Expansion on Sub-Synchronous Resonance Risk,"While transmission expansions are planned to have positive impact on
+reliability of power grids, they could increase the risk and severity of some
+of the detrimental incidents in power grid mainly by virtue of changing system
+configuration, consequently electrical distance. This paper aims to evaluate
+and quantify the impact of transmission expansion projects on Sub-Synchronous
+Resonance (SSR) risk through a two-step approach utilizing outage count index
+and Sub-synchronous damping index. A graph-theory based SSR screening tool is
+introduced to quantify the outage count associated with all grid contingencies
+which results in radial connection between renewable generation resources and
+nearby series compensated lines. Moreover, a frequency-scan based damping
+analysis is performed to assess the impact of transmission expansion on the
+system damping in sub-synchronous frequency range. The proposed approach has
+been utilized to evaluate the impact of recently-built transmission expansion
+project on SSR risk in a portion of Electric Reliability Council of Texas
+(ERCOT) grid.",1909.11024v1
+2019-10-02,Data-Driven Identification of Rayleigh-Damped Second-Order Systems,"In this paper, we present a data-driven approach to identify second-order
+systems, having internal Rayleigh damping. This means that the damping matrix
+is given as a linear combination of the mass and stiffness matrices. These
+systems typically appear when performing various engineering studies, e.g.,
+vibrational and structural analysis. In an experimental setup, the frequency
+response of a system can be measured via various approaches, for instance, by
+measuring the vibrations using an accelerometer. As a consequence, given
+frequency samples, the identification of the underlying system relies on
+rational approximation. To that aim, we propose an identification of the
+corresponding second-order system, extending the Loewner framework for this
+class of systems. The efficiency of the proposed method is demonstrated by
+means of various numerical benchmarks.",1910.00838v1
+2019-10-06,Deterministic and random attractors for a wave equation with sign changing damping,"The paper gives a detailed study of long-time dynamics generated by weakly
+damped wave equations in bounded 3D domains where the damping exponent depends
+explicitly on time and may change sign. It is shown that in the case when the
+non-linearity is superlinear, the considered equation remains dissipative if
+the weighted mean value of the dissipation rate remains positive and that the
+conditions of this type are not sufficient in the linear case. Two principally
+different cases are considered. In the case when this mean is uniform (which
+corresponds to deterministic dissipation rates), it is shown that the
+considered system possesses smooth uniform attractors as well as non-autonomous
+exponential attractors. In the case where the mean is not uniform (which
+corresponds to the random dissipation rate, for instance, when this dissipation
+rate is generated by the Bernoulli process), the tempered random attractor is
+constructed. In contrast to the usual situation, this random attractor is
+expected to have infinite Hausdorff and fractal dimension. The simplified model
+example which demonstrates infinite-dimensionality of the random attractor is
+also presented.",1910.02430v1
+2019-10-23,On the exponential stability of a stratified flow to the 2D IDEAL MHD equations with damping,"We study the stability of a type of stratified flows of the two dimensional
+inviscid incompressible MHD equations with velocity damping. The exponential
+stability for the perturbation near certain stratified flow is investigated in
+a strip-type area R*[0,1]. Although the magnetic filed potential is governed by
+a transport equation, by using the algebraic structure of the incompressible
+condition, it turns out that the linearized MHD equations around the given
+stratified flow retain a non-local damping mechanism. After carefully analyzing
+the non-linear structure and introducing some suitable weighted energy norms,
+we get the exponential stability by combining the exponential decay in time in
+the lower order energy with that in the high order energy.",1910.10598v1
+2019-10-24,Wigner instability analysis of the damped Hirota equation,"We address the modulation instability of the Hirota equation in the presence
+of stochastic spatial incoherence and linear time-dependent
+amplification/attenuation processes via the Wigner function approach. We show
+that the modulation instability remains baseband type, though the damping
+mechanisms substantially reduce the unstable spectrum independent of the
+higher-order contributions (e.g. the higher-order nonlinear interaction and the
+third-order dispersion). Additionally, we find out that the unstable structure
+due to the Kerr interaction exhibits a significant resilience to the
+third-order-dispersion stabilizing effects in comparison with the higher-order
+nonlinearity, as well as a moderate Lorentzian spectrum damping may assist the
+rising of instability. Finally, we also discuss the relevance of our results in
+the context of current experiments exploring extreme wave events driven by the
+modulation instability (e.g. the generation of the so-called rogue waves).",1910.11045v2
+2019-11-01,The spherical multipole resonance probe: kinetic damping in its spectrum,"The multipole resonance probe is one of the recently developed measurement
+devices to measure plasma parameter like electron density and temperature based
+on the concept of active plasma resonance spectroscopy. The dynamical
+interaction between the probe and the plasma in electrostatic, kinetic
+description can be modeled in an abstract notation based on functional analytic
+methods. These methods provide the opportunity to derive a general solution,
+which is given as the response function of the probe-plasma system. It is
+defined by the matrix elements of the resolvent of an appropriate dynamical
+operator. Based on the general solution a residual damping for vanishing
+pressure can be predicted and can only be explained by kinetic effects. Within
+this manuscript an explicit response function of the multipole resonance probe
+is derived. Therefore, the resolvent is determined by its algebraic
+representation based on an expansion in orthogonal basis functions. This allows
+to compute an approximated response function and its corresponding spectra,
+which show additional damping due to kinetic effects.",1911.00514v1
+2019-11-04,Current-driven skyrmion motion in granular films,"Current-driven skyrmion motion in random granular films is investigated with
+interesting findings. For a given current, there exists a critical disorder
+strength below which its transverse motion could either be boosted below a
+critical damping or be hindered above the critical damping, resulting in
+current and disorder dependences of skyrmion Hall angle. The boosting comes
+mainly from the random force that is opposite to the driving force (current).
+The critical damping depends on the current density and disorder strength.
+However, the longitudinal motion of a skyrmion is always hindered by the
+disorder. Above the critical disorder strength, skyrmions are pinned. The
+disorder-induced random force on a skyrmion can be classified as static and
+kinetic ones, similar to the friction force in the Newtonian mechanics. In the
+pinning phase, the static (pinning) random force is transverse to the current
+density. The kinetic random force is opposite to the skyrmion velocity when
+skyrmions are in motion. Furthermore, we provide strong evidences that the
+Thiele equation can perfectly describe skyrmion dynamics in granular films.
+These findings provide insight to skyrmion motion and should be important for
+skyrmiontronics.",1911.01245v1
+2019-11-05,"Reduction of damped, driven Klein-Gordon equations into a discrete nonlinear Schrödinger equation: justification and numerical comparisons","We consider a discrete nonlinear Klein-Gordon equations with damping and
+external drive. Using a small amplitude ansatz, one usually approximates the
+equation using a damped, driven discrete nonlinear Schr\""odinger equation.
+Here, we show for the first time the justification of this approximation by
+finding the error bound using energy estimate. Additionally, we prove the local
+and global existence of the Schr\""odinger equation. Numerical simulations are
+performed that describe the analytical results. Comparisons between discrete
+breathers of the Klein-Gordon equation and discrete solitons of the discrete
+nonlinear Schr\""odinger equation are presented.",1911.01631v1
+2019-11-14,Stability of coupled solitary wave in biomembranes and nerves,"In this work, we consider the electromechanical density pulse as a coupled
+solitary waves represented by a longitudinal compression wave and an
+out-of-plane transversal wave (i.e., perpendicular to the membrane surface). We
+analyzed using, the variational approach, the characteristics of the coupled
+solitary waves in the presence of damping within the framework of coupled
+nonlinear Burger-Korteweg-de Vries-Benjamin-Bona-Mahony (BKdV-BBM) equation. It
+is shown that, the inertia parameter increases the stability of coupled
+solitary waves while the damping parameter decreases it. Moreover, the presence
+of damping term induces a discontinuity of stable regions in the inertia-speed
+parameter space, appearing in he form of an island of points. Bell shape and
+solitary-shock like wave profiles were obtained by varying the propagation
+speed and their linear stability spectrum computed. It is shown that bell shape
+solitary wave exhibit bound state eigenvalue spectrum, therefore stable. On the
+other hand, the solitary-shock like wave profiles exhibit unbound state
+eigenvalue spectrum and are therefore generally unstable.",1911.05993v1
+2019-11-19,On the theory of the nonlinear Landau damping,"An exact solution of the collisionless time-dependent Vlasov equation is
+found for the first time. By means of this solution the behavior of the
+Langmuir waves in the nonlinear stage is considered. The analysis is restricted
+by the consideration of the first nonlinear approximation keeping the second
+power of the electric strength. It is shown that in general the waves with
+finite amplitudes are not subject to damping. Only in the linear approximation,
+when the wave amplitude is very small, are the waves experiencing damping. It
+is shown that with the definite resonance conditions imposed, the waves become
+unstable.",1911.08294v2
+2019-11-16,Justification of the discrete nonlinear Schrödinger equation from a parametrically driven damped nonlinear Klein-Gordon equation and numerical comparisons,"We consider a damped, parametrically driven discrete nonlinear Klein-Gordon
+equation, that models coupled pendula and micromechanical arrays, among others.
+To study the equation, one usually uses a small-amplitude wave ansatz, that
+reduces the equation into a discrete nonlinear Schr\""odinger equation with
+damping and parametric drive. Here, we justify the approximation by looking for
+the error bound with the method of energy estimates. Furthermore, we prove the
+local and global existence of {solutions to the discrete nonlinear}
+Schr\""odinger equation. To illustrate the main results, we consider numerical
+simulations showing the dynamics of errors made by the discrete nonlinear
+equation. We consider two types of initial conditions, with one of them being a
+discrete soliton of the nonlinear Schr\""odinger equation, that is expectedly
+approximate discrete breathers of the nonlinear Klein-Gordon equation.",1911.08514v1
+2019-11-26,On the Complexity of Minimum-Cost Networked Estimation of Self-Damped Dynamical Systems,"In this paper, we consider the optimal design of networked estimators to
+minimize the communication/measurement cost under the networked observability
+constraint. This problem is known as the minimum-cost networked estimation
+problem, which is generally claimed to be NP-hard. The main contribution of
+this work is to provide a polynomial-order solution for this problem under the
+constraint that the underlying dynamical system is self-damped. Using
+structural analysis, we subdivide the main problem into two NP-hard subproblems
+known as (i) optimal sensor selection, and (ii) minimum-cost communication
+network. For self-damped dynamical systems, we provide a polynomial-order
+solution for subproblem (i). Further, we show that the subproblem (ii) is of
+polynomial-order complexity if the links in the communication network are
+bidirectional. We provide an illustrative example to explain the methodologies.",1911.11381v1
+2020-01-06,A continuous contact force model for impact analysis in multibody dynamics,"A new continuous contact force model for contacting problems with regular or
+irregular contacting surfaces and energy dissipations in multibody systems is
+presented and discussed in this work. The model is developed according to Hertz
+law and a hysteresis damping force is introduced for modeling the energy
+dissipation during the contact process. As it is almost impossible to obtain an
+analytical solution based on the system dynamic equation, an approximate
+dynamic equation for the collision system is proposed, achieving a good
+approximation of the system dynamic equation. An approximate function between
+deformation velocity and deformation is founded on the approximate dynamic
+equation, then it is utilized to calculate the energy loss due to the damping
+force. The model is established through modifying the original formula of the
+hysteresis damping parameter derived by combining the energy balance and the
+law of conservation of linear momentum. Numerical results of five different
+continuous contact models reveal the capability of our new model as well as the
+effect of the geometry of the contacting surfaces on the dynamic system
+response.",2001.01344v1
+2020-01-06,Boresight Alignment of DArk Matter Particle Explorer,"The DArk Matter Particle Explorer (DAMPE) can measure $\gamma$-rays in the
+energy range from a few GeV to about 10 TeV. The direction of each $\gamma$-ray
+is reconstructed with respect to the reference system of the DAMPE payload. In
+this paper, we adopt a maximum likelihood method and use the $\gamma$-ray data
+centered around several bright point-like sources to measure and correct the
+angular deviation from the real celestial coordinate system, the so called
+``boresight alignment'' of the DAMPE payload. As a check, we also estimate the
+boresight alignment for some sets of simulation data with artificial
+orientation and obtain consistent results. The time-dependent boresight
+alignment analysis does not show evidence for significant variation of the
+parameters.",2001.01804v1
+2020-01-09,Nonlinear inviscid damping near monotonic shear flows,"We prove nonlinear asymptotic stability of a large class of monotonic shear
+flows among solutions of the 2D Euler equations in the channel
+$\mathbb{T}\times[0,1]$. More precisely, we consider shear flows $(b(y),0)$
+given by a function $b$ which is Gevrey smooth, strictly increasing, and linear
+outside a compact subset of the interval $(0,1)$ (to avoid boundary
+contributions which are incompatible with inviscid damping). We also assume
+that the associated linearized operator satisfies a suitable spectral
+condition, which is needed to prove linear inviscid damping.
+  Under these assumptions, we show that if $u$ is a solution which is a small
+and Gevrey smooth perturbation of such a shear flow $(b(y),0)$ at time $t=0$,
+then the velocity field $u$ converges strongly to a nearby shear flow as the
+time goes to infinity. This is the first nonlinear asymptotic stability result
+for Euler equations around general steady solutions for which the linearized
+flow cannot be explicitly solved.",2001.03087v1
+2020-02-03,Semi-active $\mathcal{H}_{\infty}$ damping optimization by adaptive interpolation,"In this work we consider the problem of semi-active damping optimization of
+mechanical systems with fixed damper positions. Our goal is to compute a
+damping that is locally optimal with respect to the $\mathcal{H}_\infty$-norm
+of the transfer function from the exogenous inputs to the performance outputs.
+We make use of a new greedy method for computing the $\mathcal{H}_\infty$-norm
+of a transfer function based on rational interpolation. In this paper, this
+approach is adapted to parameter-dependent transfer functions. The
+interpolation leads to parametric reduced-order models that can be optimized
+more efficiently. At the optimizers we then take new interpolation points to
+refine the reduced-order model and to obtain updated optimizers. In our
+numerical examples we show that this approach normally converges fast and thus
+can highly accelerate the optimization procedure. Another contribution of this
+work are heuristics for choosing initial interpolation points.",2002.00617v1
+2020-03-25,A Novel Wide-Area Control Strategy for Damping of Critical Frequency Oscillations via Modulation of Active Power Injections,"This paper proposes a novel wide-area control strategy for modulating the
+active power injections to damp the critical frequency oscillations in power
+systems, this includes the inter-area oscillations and the transient frequency
+swing. The proposed method pursues an efficient utilization of the limited
+power reserve of existing distributed energy resources (DERs) to mitigate these
+oscillations. This is accomplished by decoupling the damping control actions at
+different sites using the oscillation signals of the concerned mode as the
+power commands. A theoretical basis for this decoupled modulating control is
+provided. Technically, the desired sole modal oscillation signals are filtered
+out by linearly combining the system-wide frequencies, which is determined by
+the linear quadratic regulator based sparsity-promoting (LQRSP) technique. With
+the proposed strategy, the modulation of each active power injection can be
+effectively engineered considering the response limit and steady-state output
+capability of the supporting device. The method is validated based on a
+two-area test system and is further demonstrated based on the New England
+39-bus test system.",2003.11397v1
+2020-03-25,Sharp ultimate velocity bounds for the general solution of some linear second order evolution equation with damping and bounded forcing,"We consider a class of linear second order differential equations with
+damping and external force. We investigate the link between a uniform bound on
+the forcing term and the corresponding ultimate bound on the velocity of
+solutions, and we study the dependence of that bound on the damping and on the
+""elastic force"".
+  We prove three results. First of all, in a rather general setting we show
+that different notions of bound are actually equivalent. Then we compute the
+optimal constants in the scalar case. Finally, we extend the results of the
+scalar case to abstract dissipative wave-type equations in Hilbert spaces. In
+that setting we obtain rather sharp estimates that are quite different from the
+scalar case, in both finite and infinite dimensional frameworks.
+  The abstract theory applies, in particular, to dissipative wave, plate and
+beam equations.",2003.11579v1
+2020-03-28,Energy correction based on fluorescence attenuation of DAMPE,"The major scientific goals of DArk Matter Particle Explorer (DAMPE) are to
+study cosmic-ray electrons (including positrons) and gamma rays from 5 GeV to
+10 TeV and nuclei from Z = 1 to 26 up to 100 TeV. The deposited energy measured
+by the Bismuth Germanate Oxide (BGO) calorimeter of DAMPE is affected by
+fluorescence attenuation in BGO crystals that are 600 mm long. In this work, an
+in-orbit attenuation calibration method is reported, and energy correction of
+the sensitive detector unit of the BGO calorimeter is also presented.",2003.12717v1
+2020-04-02,A finite element model for seismic response analysis of free-standing rocking columns with vertical dampers,"This paper investigates finite-element modeling of a vertically damped
+free-standing rocking column. The paper first derives the nonlinear equation of
+motion for the coupled system and then compares the analytical solution with
+finite-element model. Finite-element model is being produced using open source
+framework named OpenSees. The rocking surface is modeled using zero-length
+fiber cross-section element and the dampers are modeled with two node link
+elements. In order to simulate energy dissipation during the rocking motion
+Hilber-Hughes-Taylor numerical dissipative time step integration is being
+adopted. The paper also compares two types of hysteretic and viscous damping
+devices and it shows that the viscous damping behavior is favorable when it is
+used along with a rocking block. The results of analytical model of a rigid
+block with viscous dampers in MATLAB is then compared with OpenSees model and
+the paper concludes that the finite-element model compares satisfactory with
+the analytical model.",2004.01060v1
+2020-04-02,Simulating the effect of weak measurements by a phase damping channel and determining different measures of bipartite correlations in nuclear magnetic resonance,"Quantum discord is a measure based on local projective measurements which
+captures quantum correlations that may not be fully captured by entanglement. A
+change in the measurement process, achieved by replacing rank-one projectors
+with a weak positive operator-valued measure (POVM), allows one to define weak
+variants of quantum discord. In this work, we experimentally simulate the
+effect of a weak POVM on a nuclear magnetic resonance quantum information
+processor. The two-qubit system under investigation is part of a three-qubit
+system, where one of the qubits is used as an ancillary to implement the phase
+damping channel. The strength of the weak POVM is controlled by varying the
+strength of the phase damping channel. We experimentally observed two weak
+variants of quantum discord namely, super quantum discord and weak quantum
+discord, in two-qubit Werner and Bell-diagonal states. The resultant dynamics
+of the states is investigated as a function of the measurement strength.",2004.01237v2
+2020-04-24,A rigorous derivation and energetics of a wave equation with fractional damping,"We consider a linear system that consists of a linear wave equation on a
+horizontal hypersurface and a parabolic equation in the half space below. The
+model describes longitudinal elastic waves in organic monolayers at the
+water-air interface, which is an experimental setup that is relevant for
+understanding wave propagation in biological membranes. We study the scaling
+regime where the relevant horizontal length scale is much larger than the
+vertical length scale and provide a rigorous limit leading to a
+fractionally-damped wave equation for the membrane. We provide the associated
+existence results via linear semigroup theory and show convergence of the
+solutions in the scaling limit. Moreover, based on the energy-dissipation
+structure for the full model, we derive a natural energy and a natural
+dissipation function for the fractionally-damped wave equation with a time
+derivative of order 3/2",2004.11830v1
+2020-04-25,Pulse-assisted magnetization switching in magnetic nanowires at picosecond and nanosecond timescales with low energy,"Detailed understanding of spin dynamics in magnetic nanomaterials is
+necessary for developing ultrafast, low-energy and high-density spintronic
+logic and memory. Here, we develop micromagnetic models and analytical
+solutions to elucidate the effect of increasing damping and uniaxial anisotropy
+on magnetic field pulse-assisted switching time, energy and field requirements
+of nanowires with perpendicular magnetic anisotropy and yttrium iron
+garnet-like spin transport properties. A nanowire is initially magnetized using
+an external magnetic field pulse (write) and self-relaxation. Next, magnetic
+moments exhibit deterministic switching upon receiving 2.5 ns-long external
+magnetic pulses in both vertical polarities. Favorable damping
+({\alpha}~0.1-0.5) and anisotropy energies (10^4-10^5 J m^-3) allow for as low
+as picosecond magnetization switching times. Magnetization reversal with fields
+below coercivity was observed using spin precession instabilities. A
+competition or a nanomagnetic trilemma arises among the switching rate, energy
+cost and external field required. Developing magnetic nanowires with optimized
+damping and effective anisotropy could reduce the switching energy barrier down
+to 3163kBT at room temperature. Thus, pulse-assisted picosecond and low energy
+switching in nanomagnets could enable ultrafast nanomagnetic logic and cellular
+automata.",2004.12243v1
+2020-05-01,Stability of Forced-Damped Response in Mechanical Systems from a Melnikov Analysis,"Frequency responses of multi-degree-of-freedom mechanical systems with weak
+forcing and damping can be studied as perturbations from their conservative
+limit. Specifically, recent results show how bifurcations near resonances can
+be predicted analytically from conservative families of periodic orbits
+(nonlinear normal modes). However, the stability of forced-damped motions is
+generally determined a posteriori via numerical simulations. In this paper, we
+present analytic results on the stability of periodic orbits that perturb from
+conservative nonlinear normal modes. In contrast with prior approaches to the
+same problem, our method can tackle strongly nonlinear oscillations, high-order
+resonances and arbitrary types of non-conservative forces affecting the system,
+as we show with specific examples.",2005.00444v2
+2020-05-13,Periodically Forced Nonlinear Oscillators With Hysteretic Damping,"We perform a detailed study of the dynamics of a nonlinear, one-dimensional
+oscillator driven by a periodic force under hysteretic damping, whose linear
+version was originally proposed and analyzed by Bishop in [1]. We first add a
+small quadratic stiffness term in the constitutive equation and construct the
+periodic solution of the problem by a systematic perturbation method,
+neglecting transient terms as $t\rightarrow \infty$. We then repeat the
+analysis replacing the quadratic by a cubic term, which does not allow the
+solutions to escape to infinity. In both cases, we examine the dependence of
+the amplitude of the periodic solution on the different parameters of the model
+and discuss the differences with the linear model. We point out certain
+undesirable features of the solutions, which have also been alluded to in the
+literature for the linear Bishop's model, but persist in the nonlinear case as
+well. Finally, we discuss an alternative hysteretic damping oscillator model
+first proposed by Reid [2], which appears to be free from these difficulties
+and exhibits remarkably rich dynamical properties when extended in the
+nonlinear regime.",2005.06187v1
+2020-05-13,Magnetic circular dichroism spectra from resonant and damped coupled cluster response theory,"A computational expression for the Faraday A term of magnetic circular
+dichroism (MCD) is derived within coupled cluster response theory and
+alternative computational expressions for the B term are discussed. Moreover,
+an approach to compute the (temperature-independent) MCD ellipticity in the
+context of coupled cluster damped response is presented, and its equivalence
+with the stick-spectrum approach in the limit of infinite lifetimes is
+demonstrated. The damped response approach has advantages for molecular systems
+or spectral ranges with a high density of states. Illustrative results are
+reported at the coupled cluster singles and doubles level and compared to
+time-dependent density functional theory results.",2005.06190v1
+2020-05-21,Convective Excitation and Damping of Solar-like Oscillations,"The last decade has seen a rapid development in asteroseismology thanks to
+the CoRoT and Kepler missions. With more detailed asteroseismic observations
+available, it is becoming possible to infer exactly how oscillations are driven
+and dissipated in solar-type stars. We have carried out three-dimensional (3D)
+stellar atmosphere simulations together with one-dimensional (1D) stellar
+structural models of key benchmark turn-off and subgiant stars to study this
+problem from a theoretical perspective. Mode excitation and damping rates are
+extracted from 3D and 1D stellar models based on analytical expressions. Mode
+velocity amplitudes are determined by the balance between stochastic excitation
+and linear damping, which then allows the estimation of the frequency of
+maximum oscillation power, $\nu_{\max}$, for the first time based on ab initio
+and parameter-free modelling. We have made detailed comparisons between our
+numerical results and observational data and achieved very encouraging
+agreement for all of our target stars. This opens the exciting prospect of
+using such realistic 3D hydrodynamical stellar models to predict solar-like
+oscillations across the HR-diagram, thereby enabling accurate estimates of
+stellar properties such as mass, radius and age.",2005.10519v1
+2020-05-21,Non-Markovian memory in a measurement-based quantum computer,"We study the exact open system dynamics of single qubit gates during a
+measurement-based quantum computation considering non-Markovian environments.
+We obtain analytical solutions for the average gate fidelities and analyze it
+for amplitude damping and dephasing channels. We show that the average fidelity
+is identical for the X-gate and Z-gate and that neither fast application of the
+projective measurements necessarily implies high gate fidelity, nor slow
+application necessarily implies low gate fidelity. Indeed, for highly
+non-Markovian environments, it is of utmost importance to know the best time to
+perform the measurements, since a huge variation in the gate fidelity may occur
+given this scenario. Furthermore, we show that while for the amplitude damping
+the knowledge of the dissipative map is sufficient to determine the best
+measurement times, i.e. the best times in which measures are taken, the same is
+not necessarily true for the phase damping. To the later, the time of the set
+of measures becomes crucial since a phase error in one qubit can fix the phase
+error that takes place in another.",2005.10883v1
+2020-05-22,Improving Dynamic Performance of Low-Inertia Systems through Eigensensitivity Optimization,"An increasing penetration of renewable generation has led to reduced levels
+of rotational inertia and damping in the system. The consequences are higher
+vulnerability to disturbances and deterioration of the dynamic response of the
+system. To overcome these challenges, novel converter control schemes that
+provide virtual inertia and damping have been introduced, which raises the
+question of optimal distribution of such devices throughout the network. This
+paper presents a framework for performance-based allocation of virtual inertia
+and damping to the converter-interfaced generators in a low-inertia system.
+This is achieved through an iterative, eigensensitivity-based optimization
+algorithm that determines the optimal controller gains. Two conceptually
+different problem formulations are presented and validated on a 3-area, 12-bus
+test system.",2005.11032v1
+2020-05-24,Theory of Solutions for An Inextensible Cantilever,"Recent equations of motion for the large deflections of a cantilevered
+elastic beam are analyzed. In the traditional theory of beam (and plate) large
+deflections, nonlinear restoring forces are due to the effect of stretching on
+bending; for an inextensible cantilever, the enforcement of arc-length
+preservation leads to quasilinear stiffness effects and inertial effects that
+are both nonlinear and nonlocal. For this model, smooth solutions are
+constructed via a spectral Galerkin approach. Additional compactness is needed
+to pass to the limit, and this is obtained through a complex procession of
+higher energy estimates. Uniqueness is obtained through a non-trivial
+decomposition of the nonlinearity. The confounding effects of nonlinear inertia
+are overcome via the addition of structural (Kelvin-Voigt) damping to the
+equations of motion. Local well-posedness of smooth solutions is shown first in
+the absence of nonlinear inertial effects, and then shown with these inertial
+effects present, taking into account structural damping. With damping in force,
+global-in-time, strong well-posedness result is obtained by achieving
+exponential decay for small data.",2005.11836v2
+2020-05-25,Nonlinear losses in magnon transport due to four-magnon scattering,"We report on the impact of nonlinear four-magnon scattering on magnon
+transport in microstructured Co25Fe75 waveguides with low magnetic damping. We
+determine the magnon propagation length with microfocused Brillouin light
+scattering over a broad range of excitation powers and detect a decrease of the
+attenuation length at high powers. This is consistent with the onset of
+nonlinear four-magnon scattering. Hence, it is critical to stay in the linear
+regime, when deriving damping parameters from the magnon propagation length.
+Otherwise, the intrinsic nonlinearity of magnetization dynamics may lead to a
+misinterpretation of magnon propagation lengths and, thus, to incorrect values
+of the magnetic damping of the system.",2005.12113v2
+2020-06-02,Rigid body dynamics of diamagnetically levitating graphite resonators,"Diamagnetic levitation is a promising technique for realizing resonant
+sensors and energy harvesters, since it offers thermal and mechanical isolation
+from the environment at zero power. To advance the application of
+diamagnetically levitating resonators, it is important to characterize their
+dynamics in the presence of both magnetic and gravitational fields. Here we
+experimentally actuate and measure rigid body modes of a diamagnetically
+levitating graphite plate. We numerically calculate the magnetic field and
+determine the influence of magnetic force on the resonance frequencies of the
+levitating plate. By analyzing damping mechanisms, we conclude that eddy
+current damping dominates dissipation in mm-sized plates. We use finite element
+simulations to model eddy current damping and find close agreement with
+experimental results. We also study the size-dependent Q-factors (Qs) of
+diamagnetically levitating plates and show that Qs above 100 million are
+theoretically attainable by reducing the size of the diamagnetic resonator down
+to microscale, making these systems of interest for next generation low-noise
+resonant sensors and oscillators.",2006.01733v3
+2020-06-11,Signatures of Spatial Curvature on Growth of Structures,"We write down Boltzmann equation for massive particles in a spatially curved
+FRW universe and solve the approximate line-of-sight solution for evolution of
+matter density, including the effects of spatial curvature to the first order
+of approximation. It is shown that memory of early time gravitational potential
+is affected by presence of spatial curvature. Then we revisit Boltzmann
+equation for photons in the general FRW background. Using it, we show that how
+the frequency of oscillations and damping factor (known as Silk damping)
+changed in presence of spatial curvature. At last, using this modified damping
+factor in hydrodynamic regime of cosmological perturbations, we find our
+analytic solution which shows the effects of spatial curvature on growing mode
+of matter density.",2006.06347v2
+2020-06-29,"HFQPOs and discoseismic mode excitation in eccentric, relativistic discs. II. Magnetohydrodynamic simulations","Trapped inertial oscillations (r-modes) provide a promising explanation for
+high-frequency quasi-periodic oscillations (HFQPOs) observed in the emission
+from black hole X-ray binary systems. An eccentricity (or warp) can excite
+r-modes to large amplitudes, but concurrently the oscillations are likely
+damped by magnetohydrodynamic (MHD) turbulence driven by the magnetorotational
+instability (MRI). We force eccentricity in global, unstratified, zero-net flux
+MHD simulations of relativistic accretion discs, and find that a sufficiently
+strong disc distortion generates trapped inertial waves despite this damping.
+In our simulations, eccentricities above ~ 0.03 in the inner disc excite
+trapped waves. In addition to the competition between r-mode damping and
+driving, we observe that larger amplitude eccentric structures modify and in
+some cases suppress MRI turbulence. Given the variety of distortions (warps as
+well as eccentricities) capable of amplifying r-modes, the robustness of
+trapped inertial wave excitation in the face of MRI turbulence in our
+simulations provides support for a discoseismic explanation for HFQPOs.",2006.16266v2
+2020-07-01,"An integrable family of torqued, damped, rigid rotors","Expositions of the Euler equations for the rotation of a rigid body often
+invoke the idea of a specially damped system whose energy dissipates while its
+angular momentum magnitude is conserved in the body frame. An attempt to
+explicitly construct such a damping function leads to a more general, but still
+integrable, system of cubic equations whose trajectories are confined to nested
+sets of quadric surfaces in angular momentum space. For some choices of
+parameters, the lines of fixed points along both the largest and smallest
+moment of inertia axes can be simultaneously attracting. Limiting cases are
+those that conserve either the energy or the magnitude of the angular momentum.
+Parallels with rod mechanics, micromagnetics, and particles with effective mass
+are briefly discussed.",2007.00707v1
+2020-07-10,Approximate Time-Optimal Trajectories for Damped Double Integrator in 2D Obstacle Environments under Bounded Inputs,"This article provides extensions to existing path-velocity decomposition
+based time optimal trajectory planning algorithm \cite{kant1986toward} to
+scenarios in which agents move in 2D obstacle environment under double
+integrator dynamics with drag term (damped double integrator). Particularly, we
+extend the idea of a tangent graph \cite{liu1992path} to $\calC^1$-Tangent
+graph to find continuously differentiable ($\calC^1$) shortest path between any
+two points. $\calC^1$-Tangent graph has a continuously differentiable
+($\calC^1$) path between any two nodes. We also provide analytical expressions
+for a near time-optimal velocity profile for an agent moving on these shortest
+paths under the damped double integrator with bounded acceleration.",2007.05155v2
+2020-08-11,Ab initio results for the plasmon dispersion and damping of the warm dense electron gas,"Warm dense matter (WDM) is an exotic state on the border between condensed
+matter and dense plasmas. Important occurrences of WDM include dense
+astrophysical objects, matter in the core of our Earth, as well as matter
+produced in strong compression experiments. As of late, x-ray Thomson
+scattering has become an advanced tool to diagnose WDM. The interpretation of
+the data requires model input for the dynamic structure factor $S(q,\omega)$
+and the plasmon dispersion $\omega(q)$. Recently the first \textit{ab initio}
+results for $S(q,\omega)$ of the homogeneous warm dense electron gas were
+obtained from path integral Monte Carlo simulations, [Dornheim \textit{et al.},
+Phys. Rev. Lett. \textbf{121}, 255001 (2018)]. Here, we analyse the effects of
+correlations and finite temperature on the dynamic dielectric function and the
+plasmon dispersion. Our results for the plasmon dispersion and damping differ
+significantly from the random phase approximation and from earlier models of
+the correlated electron gas. Moreover, we show when commonly used weak damping
+approximations break down and how the method of complex zeros of the dielectric
+function can solve this problem for WDM conditions.",2008.04605v1
+2020-08-18,"Survey of 360$^{\circ}$ domain walls in magnetic heterostructures: topology, chirality and current-driven dynamics","Chirality and current-driven dynamics of topologically nontrivial
+360$^{\circ}$ domain walls (360DWs) in magnetic heterostructures (MHs) are
+systematically investigated. For MHs with normal substrates, the static 360DWs
+are N\'{e}el-type with no chirality. While for those with heavy-metal
+substrates, the interfacial Dzyaloshinskii-Moriya interaction (iDMI) therein
+makes 360DWs prefer specific chirality. Under in-plane driving charge currents,
+as the direct result of ""full-circle"" topology a certain 360DW does not undergo
+the ""Walker breakdown""-type process like a well-studied 180$^{\circ}$ domain
+wall as the current density increases. Alternatively, it keeps a fixed
+propagating mode (either steady-flow or precessional-flow, depending on the
+effective damping constant of the MH) until it collapses or changes to other
+types of solition when the current density becomes too high. Similarly, the
+field-like spin-orbit torque (SOT) has no effects on the dynamics of 360DWs,
+while the anti-damping SOT has. For both modes, modifications to the mobility
+of 360DWs by iDMI and anti-damping SOT are provided.",2008.08196v1
+2020-08-20,Combining $T_1$ and $T_2$ estimation with randomized benchmarking and bounding the diamond distance,"The characterization of errors in a quantum system is a fundamental step for
+two important goals. First, learning about specific sources of error is
+essential for optimizing experimental design and error correction methods.
+Second, verifying that the error is below some threshold value is required to
+meet the criteria of threshold theorems. We consider the case where errors are
+dominated by the generalized damping channel (encompassing the common intrinsic
+processes of amplitude damping and dephasing) but may also contain additional
+unknown error sources. We demonstrate the robustness of standard $T_1$ and
+$T_2$ estimation methods and provide expressions for the expected error in
+these estimates under the additional error sources. We then derive expressions
+that allow a comparison of the actual and expected results of fine-grained
+randomized benchmarking experiments based on the damping parameters. Given the
+results of this comparison, we provide bounds that allow robust estimation of
+the thresholds for fault-tolerance.",2008.09197v1
+2020-08-25,The atomic damping basis and the collective decay of interacting two-level atoms,"We find analytical solutions to the evolution of interacting two-level atoms
+when the master equation is symmetric under the permutation of atomic labels.
+The master equation includes atomic independent dissipation. The method to
+obtain the solutions is: First, we use the system symmetries to describe the
+evolution in an operator space whose dimension grows polynomially with the
+number of atoms. Second, we expand the solutions in a basis composed of
+eigenvectors of the dissipative part of the master equation that models the
+independent dissipation of the atoms. This atomic damping basis is an atomic
+analog to the damping basis used for bosonic fields. The solutions show that
+the system decays as a sum of sub- and super-radiant exponential terms.",2008.11056v1
+2020-09-11,Accuracy of relativistic Cowling approximation in protoneutron star asteroseismology,"The relativistic Cowling approximation, where the metric perturbations are
+neglected during the fluid oscillations, is often adopted for considering the
+gravitational waves from the protoneutron stars (PNSs) provided via
+core-collapse supernova explosions. In this study, we evaluate how the Cowling
+approximation works well by comparing the frequencies with the Cowling
+approximation to those without the approximation. Then, we find that the
+behavior of the frequencies with the approximation is qualitatively the same
+way as that without the approximation, where the frequencies with the
+approximation can totally be determined within $\sim 20\%$ accuracy. In
+particular, the fundamental mode with the Cowling approximation is
+overestimated. In addition, we also discuss the damping time of various
+eigenmodes in gravitational waves from the PNSs, where the damping time for the
+PNSs before the avoided crossing between the $f$- and $g_1$-modes, is quite
+different from that for cold neutron stars, but it is more or less similar to
+that for cold neutron stars in the later phase. The damping time is long enough
+compared to the typical time interval of short-Fourier transformation that
+often used in the analysis, and that ideally guarantees the validity of the
+transformation.",2009.05206v1
+2020-09-17,Resonant absorption: transformation of compressive motions into vortical motions,"This paper investigates the changes in spatial properties when
+magnetohydrodynamic (MHD) waves undergo resonant damping in the Alfv\'en
+continuum. The analysis is carried out for a 1D cylindrical pressure-less
+plasma with a straight magnetic field. The effect of the damping on the spatial
+wave variables is determined by using complex frequencies that arise as a
+result of the resonant damping. Compression and vorticity are used to
+characterise the spatial evolution of the MHD wave. The most striking result is
+the huge spatial variation in the vorticity component parallel to the magnetic
+field. Parallel vorticity vanishes in the uniform part of the equilibrium.
+However, when the MHD wave moves into the non-uniform part, parallel vorticity
+explodes to values that are orders of magnitude higher than those attained by
+the transverse components in planes normal to the straight magnetic field. In
+the non-uniform part of the equilibrium plasma, the MHD wave is controlled by
+parallel vorticity and resembles an Alfv\'en wave, with the unfamiliar property
+that it has pressure variations even in the linear regime.",2009.08152v1
+2020-09-19,Random vibrations of stress-driven nonlocal beams with external damping,"Stochastic flexural vibrations of small-scale Bernoulli-Euler beams with
+external damping are investigated by stress-driven nonlocal mechanics. Damping
+effects are simulated considering viscous interactions between beam and
+surrounding environment. Loadings are modeled by accounting for their random
+nature. Such a dynamic problem is characterized by a stochastic partial
+differential equation in space and time governing time-evolution of the
+relevant displacement field. Differential eigenanalyses are performed to
+evaluate modal time coordinates and mode shapes, providing a complete
+stochastic description of response solutions. Closed-form expressions of power
+spectral density, correlation function, stationary and non-stationary variances
+of displacement fields are analytically detected. Size-dependent dynamic
+behaviour is assessed in terms of stiffness, variance and power spectral
+density of displacements. The outcomes can be useful for design and
+optimization of structural components of modern small-scale devices, such as
+Micro- and Nano-Electro-Mechanical-Systems (MEMS and NEMS).",2009.09184v1
+2020-09-20,Correction Method for the Readout Saturation of the DAMPE Calorimeter,"The DArk Matter Particle Explorer (DAMPE) is a space-borne high energy
+cosmic-ray and $\gamma$-ray detector which operates smoothly since the launch
+on December 17, 2015. The bismuth germanium oxide (BGO) calorimeter is one of
+the key sub-detectors of DAMPE used for energy measurement and electron proton
+identification. For events with total energy deposit higher than decades of
+TeV, the readouts of PMTs coupled on the BGO crystals would become saturated,
+which results in an underestimation of the energy measurement. Based on
+detailed simulations, we develop a correction method for the saturation effect
+according to the shower development topologies and energies measured by
+neighbouring BGO crystals. The verification with simulated and on-orbit events
+shows that this method can well reconstruct the energy deposit in the saturated
+BGO crystal.",2009.09438v1
+2020-09-21,Complete complementarity relations in system-environment decoherent dynamics,"We investigate the system-environment information flow from the point of view
+ofcomplete complementarity relations. We consider some commonly used noisy
+quantum channels:Amplitude damping, phase damping, bit flip, bit-phase flip,
+phase flip, depolarizing, and correlatedamplitude damping. By starting with an
+entangled bipartite pure quantum state, with the linearentropy being the
+quantifier of entanglement, we study how entanglement is redistributed and
+turnedinto general correlations between the degrees of freedom of the whole
+system. For instance, it ispossible to express the entanglement entropy in
+terms of the multipartite quantum coherence or interms of the correlated
+quantum coherence of the different partitions of the system. In addition,we
+notice that for the depolarizing and bit-phase flip channels the wave and
+particle aspects candecrease or increase together. Besides, by considering the
+environment as part of a pure quantumsystem, the linear entropy is shown to be
+not just a measure of mixedness of a particular subsystem,but a correlation
+measure of the subsystem with rest of the world.",2009.09769v3
+2020-09-15,Delay-induced resonance suppresses damping-induced unpredictability,"Combined effects of the damping and forcing in the underdamped time-delayed
+Duffing oscillator are considered in this paper. We analyze the generation of a
+certain damping-induced unpredictability, due to the gradual suppression of
+interwell oscillations. We find the minimal amount of the forcing amplitude and
+the right forcing frequency to revert the effect of the dissipation, so that
+the interwell oscillations can be restored, for different time delay values.
+This is achieved by using the delay-induced resonance, in which the time delay
+replaces one of the two periodic forcings present in the vibrational resonance.
+A discussion in terms of the time delay of the critical values of the forcing
+for which the delay-induced resonance can tame the dissipation effect is
+finally carried out.",2009.11760v1
+2020-10-06,A dissiptive logarithmic type evolution equation: asymptotic profile and optimal estimates,"We introduce a new model of the logarithmic type of wave-like equation with a
+nonlocal logarithmic damping mechanism, which is rather weakly effective as
+compared with frequently studied fractional damping cases. We consider the
+Cauchy problem for this new model in the whole space, and study the asymptotic
+profile and optimal decay and/or blowup rates of solutions as time goes to
+infinity in L^{2}-sense. The operator L considered in this paper was used to
+dissipate the solutions of the wave equation in the paper studied by
+Charao-Ikehata in 2020, and in the low frequency parameters the principal part
+of the equation and the damping term is rather weakly effective than those of
+well-studied power type operators.",2010.02485v1
+2020-10-12,Line-drag damping of Alfvén waves in radiatively driven winds of magnetic massive stars,"Line-driven stellar winds from massive (OB) stars are subject to a strong
+line-deshadowing instability. Recently, spectropolarimetric surveys have
+collected ample evidence that a subset of Galactic massive stars hosts strong
+surface magnetic fields. We investigate here the propagation and stability of
+magneto-radiative waves in such a magnetised, line-driven wind. Our analytic,
+linear stability analysis includes line-scattering from the stellar radiation,
+and accounts for both radial and non-radial perturbations. We establish a
+bridging law for arbitrary perturbation wavelength after which we analyse
+separately the long- and short-wavelength limits. While long-wavelength
+radiative and magnetic waves are found to be completely decoupled, a key result
+is that short-wavelength, radially propagating Alfv\'en waves couple to the
+scattered radiation field and are strongly damped due to the line-drag effect.
+This damping of magnetic waves in a scattering-line-driven flow could have
+important effects on regulating the non-linear wind dynamics, and so might also
+have strong influence on observational diagnostics of the wind structure and
+clumping of magnetic line-driven winds.",2010.05650v1
+2020-10-20,Long Time Behavior of a Quasilinear Hyperbolic System Modelling Elastic Membranes,"The paper studies the long time behavior of a system that describes the
+motion of a piece of elastic membrane driven by surface tension and inner air
+pressure. The system is a degenerate quasilinear hyperbolic one that involves
+the mean curvature, and also includes a damping term that models the
+dissipative nature of genuine physical systems. With the presence of damping, a
+small perturbation of the sphere converges exponentially in time to the sphere,
+and without the damping the evolution that is $\varepsilon$-close to the sphere
+has life span longer than $\varepsilon^{-1/6}$. Both results are proved using a
+new Nash-Moser-H\""{o}rmander type theorem proved by Baldi and Haus.",2010.10663v6
+2020-10-09,Rapid parameter determination of discrete damped sinusoidal oscillations,"We present different computational approaches for the rapid extraction of the
+signal parameters of discretely sampled damped sinusoidal signals. We compare
+time- and frequency-domain-based computational approaches in terms of their
+accuracy and precision and computational time required in estimating the
+frequencies of such signals, and observe a general trade-off between precision
+and speed. Our motivation is precise and rapid analysis of damped sinusoidal
+signals as these become relevant in view of the recent experimental
+developments in cavity-enhanced polarimetry and ellipsometry, where the
+relevant time scales and frequencies are typically within the $\sim1-10\,\mu$s
+and $\sim1-100$MHz ranges, respectively. In such experimental efforts,
+single-shot analysis with high accuracy and precision becomes important when
+developing experiments that study dynamical effects and/or when developing
+portable instrumentations. Our results suggest that online, running-fashion,
+microsecond-resolved analysis of polarimetric/ellipsometric measurements with
+fractional uncertainties at the $10^{-6}$ levels, is possible, and using a
+proof-of-principle experimental demonstration we show that using a
+frequency-based analysis approach we can monitor and analyze signals at kHz
+rates and accurately detect signal changes at microsecond time-scales.",2010.11690v1
+2020-10-22,Effective shear and bulk viscosities for anisotropic flow,"We evaluate the viscous damping of anisotropic flow in heavy-ion collisions
+for arbitrary temperature-dependent shear and bulk viscosities. We show that
+the damping is solely determined by effective shear and bulk viscosities, which
+are weighted averages over the temperature. We determine the relevant weights
+for nucleus-nucleus collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV and 200 GeV,
+corresponding to the maximum LHC and RHIC energies, by running ideal and
+viscous hydrodynamic simulations. The effective shear viscosity is driven by
+temperatures below $210$ MeV at RHIC, and below $280$ MeV at the LHC, with the
+largest contributions coming from the lowest temperatures, just above
+freeze-out. The effective bulk viscosity is driven by somewhat higher
+temperatures, corresponding to earlier stages of the collision. We show that at
+a fixed collision energy, the effective viscosity is independent of centrality
+and system size, to the same extent as the mean transverse momentum of outgoing
+hadrons. The variation of viscous damping is determined by Reynolds number
+scaling.",2010.11919v2
+2020-10-23,Is PSR J0855$-$4644 responsible for the 1.4 TeV electron spectral bump hinted by DAMPE?,"DAMPE observation on the cosmic ray electron spectrum hints a narrow excess
+at $\sim$ 1.4 TeV. Although the excess can be ascribed to dark matter
+particles, pulsars and pulsar wind nebulae are believed to be a more natural
+astrophysical origin: electrons injected from nearby pulsars at their early
+ages can form a bump-like feature in the spectrum due to radiative energy
+losses. In this paper, with a survey of nearby pulsars, we find 4 pulsars that
+may have notable contributions to $\sim$ 1.4 TeV cosmic ray electrons. Among
+them, PSR J0855$-$4644 has a spin down luminosity more than 50 times higher
+than others and presumably dominates the electron fluxes from them. X-ray
+observations on the inner compact part (which may represent a tunnel for the
+transport of electrons from the pulsar) of PWN G267.0$-$01.0 are then used to
+constrain the spectral index of high energy electrons injected by the pulsar.
+We show that high-energy electrons released by PSR J0855$-$4644 could indeed
+reproduce the 1.4 TeV spectral feature hinted by the DAMPE with reasonable
+parameters.",2010.12170v1
+2020-11-02,Effect of retardation on the frequency and linewidth of plasma resonances in a two-dimensional disk of electron gas,"We theoretically analyze dominant plasma modes in a two-dimensional disk of
+electron gas by calculating the absorption of an incident electromagnetic wave.
+The problem is solved in a self-consistent approximation, taking into account
+electromagnetic retardation effects. We use the Drude model to describe the
+conductivity of the system. The absorption spectrum exhibits a series of peaks
+corresponding to the excitation of plasma waves. The position and linewidth of
+the peaks designating, respectively, the frequency and damping rate of the
+plasma modes. We estimate the influence of retardation effects on the frequency
+and linewidth of the fundamental (dipole) and axisymmetric (quadrupole) plasma
+modes both numerically and analytically. We find the net damping rate of the
+modes to be dependent on not only the sum of the radiative and collisional
+decays but also their intermixture, even for small retardation. We show that
+the net damping rate can be noticeably less than that determined by collisions
+alone.",2011.00877v1
+2020-11-05,Low-Complexity Models for Acoustic Scene Classification Based on Receptive Field Regularization and Frequency Damping,"Deep Neural Networks are known to be very demanding in terms of computing and
+memory requirements. Due to the ever increasing use of embedded systems and
+mobile devices with a limited resource budget, designing low-complexity models
+without sacrificing too much of their predictive performance gained great
+importance. In this work, we investigate and compare several well-known methods
+to reduce the number of parameters in neural networks. We further put these
+into the context of a recent study on the effect of the Receptive Field (RF) on
+a model's performance, and empirically show that we can achieve high-performing
+low-complexity models by applying specific restrictions on the RFs, in
+combination with parameter reduction methods. Additionally, we propose a
+filter-damping technique for regularizing the RF of models, without altering
+their architecture and changing their parameter counts. We will show that
+incorporating this technique improves the performance in various low-complexity
+settings such as pruning and decomposed convolution. Using our proposed filter
+damping, we achieved the 1st rank at the DCASE-2020 Challenge in the task of
+Low-Complexity Acoustic Scene Classification.",2011.02955v1
+2020-11-23,Sharp lifespan estimates for the weakly coupled system of semilinear damped wave equations in the critical case,"The open question, which seems to be also the final part, in terms of
+studying the Cauchy problem for the weakly coupled system of damped wave
+equations or reaction-diffusion equations, is so far known as the sharp
+lifespan estimates in the critical case. In this paper, we mainly investigate
+lifespan estimates for solutions to the weakly coupled system of semilinear
+damped wave equations in the critical case. By using a suitable test function
+method associated with nonlinear differential inequalities, we catch upper
+bound estimates for the lifespan. Moreover, we establish polynomial-logarithmic
+type time-weighted Sobolev spaces to obtain lower bound estimates for the
+lifespan in low spatial dimensions. Then, together with the derived lifespan
+estimates, new and sharp results on estimates for the lifespan in the critical
+case are claimed. Finally, we give an application of our results to the
+semilinear reaction-diffusion system in the critical case.",2011.11366v2
+2020-12-10,Stochastic Damped L-BFGS with Controlled Norm of the Hessian Approximation,"We propose a new stochastic variance-reduced damped L-BFGS algorithm, where
+we leverage estimates of bounds on the largest and smallest eigenvalues of the
+Hessian approximation to balance its quality and conditioning. Our algorithm,
+VARCHEN, draws from previous work that proposed a novel stochastic damped
+L-BFGS algorithm called SdLBFGS. We establish almost sure convergence to a
+stationary point and a complexity bound. We empirically demonstrate that
+VARCHEN is more robust than SdLBFGS-VR and SVRG on a modified DavidNet problem
+-- a highly nonconvex and ill-conditioned problem that arises in the context of
+deep learning, and their performance is comparable on a logistic regression
+problem and a nonconvex support-vector machine problem.",2012.05783v1
+2020-12-29,Twist-induced Near-field Thermal Switch Using Nonreciprocal Surface Magnon-Polaritons,"We explore that two ferromagnetic insulator slabs host a strong twist-induced
+near-field radiative heat transfer in the presence of twisted magnetic fields.
+Using the formalism of fluctuational electrodynamics, we find the existence of
+large twist-induced thermal switch ratio in large damping condition and
+nonmonotonic twist manipulation for heat transfer in small damping condition,
+associated with the different twist-induced effects of nonreciprocal elliptic
+surface magnon-polaritons, hyperbolic surface magnon-polaritons, and
+twist-non-resonant surface magnon-polaritons. Moreover, the near-field
+radiative heat transfer can be significantly enhanced by the twist-non-resonant
+surface magnon-polaritons in the ultra-small damping condition. Such
+twist-induced effect is applicable for other kinds of anisotropic slabs with
+timereversal symmetry breaking. Our findings provide a way to twisted and
+magnetic control in nanoscale thermal management and improve it with
+twistronics concepts.",2012.14733v1
+2021-01-04,The damped harmonic oscillator at the classical limit of the Snyder-de Sitter space,"Valtancoli in his paper entitled [P. Valtancoli, Canonical transformations,
+and minimal length J. Math. Phys. 56, 122107 (2015)] has shown how the
+deformation of the canonical transformations can be made compatible with the
+deformed Poisson brackets. Based on this work and through an appropriate
+canonical transformation, we solve the problem of one dimensional (1D) damped
+harmonic oscillator at the classical limit of the Snyder-de Sitter (SdS) space.
+We show that the equations of the motion can be described by trigonometric
+functions with frequency and period depending on the deformed and the damped
+parameters. We eventually discuss the influences of these parameters on the
+motion of the system.",2101.01223v2
+2021-01-26,Generalized Damped Newton Algorithms in Nonsmooth Optimization via Second-Order Subdifferentials,"The paper proposes and develops new globally convergent algorithms of the
+generalized damped Newton type for solving important classes of nonsmooth
+optimization problems. These algorithms are based on the theory and
+calculations of second-order subdifferentials of nonsmooth functions with
+employing the machinery of second-order variational analysis and generalized
+differentiation. First we develop a globally superlinearly convergent damped
+Newton-type algorithm for the class of continuously differentiable functions
+with Lipschitzian gradients, which are nonsmooth of second order. Then we
+design such a globally convergent algorithm to solve a structured class of
+nonsmooth quadratic composite problems with extended-real-valued cost
+functions, which typically arise in machine learning and statistics. Finally,
+we present the results of numerical experiments and compare the performance of
+our main algorithm applied to an important class of Lasso problems with those
+achieved by other first-order and second-order optimization algorithms.",2101.10555v3
+2021-01-26,Damped and Driven Breathers and Metastability,"In this article we prove the existence of a new family of periodic solutions
+for discrete, nonlinear Schrodinger equations subject to spatially localized
+driving and damping. They provide an alternate description of the metastable
+behavior in such lattice systems which agrees with previous predictions for the
+evolution of metastable states while providing more accurate approximations to
+these states. We analyze the stability of these breathers, finding a very small
+positive eigenvalue whose eigenvector lies almost tangent to the surface of the
+cylinder formed by the family of breathers. This causes solutions to slide
+along the cylinder without leaving its neighborhood for very long times.",2101.10999v2
+2021-02-05,A simple artificial damping method for total Lagrangian smoothed particle hydrodynamics,"In this paper, we present a simple artificial damping method to enhance the
+robustness of total Lagrangian smoothed particle hydrodynamics (TL-SPH).
+Specifically, an artificial damping stress based on the Kelvin-Voigt type
+damper with a scaling factor imitating a von Neumann-Richtmyer type artificial
+viscosity is introduced in the constitutive equation to alleviate the spurious
+oscillation in the vicinity of the sharp spatial gradients. After validating
+the robustness and accuracy of the present method with a set of benchmark tests
+with very challenging cases, we demonstrate its potentials in the field of
+bio-mechanics by simulating the deformation of complex stent structures.",2102.04898v1
+2021-02-18,Probing black hole microstructure with the kinetic turnover of phase transition,"By treating black hole as the macroscopic stable state on the free energy
+landscape, we propose that the stochastic dynamics of the black hole phase
+transition can be effectively described by the Langevin equation or
+equivalently by the Fokker-Planck equation in phase space. We demonstrate the
+turnover of the kinetics for the charged anti-de Sitter black hole phase
+transition, which shows that the mean first passage time is linear with the
+friction in the high damping regime and inversely proportional to the friction
+in the low damping regime. The fluctuations in the kinetics are shown to be
+large/small in the high/low damping regime and the switching behavior from the
+small fluctuations to the large fluctuations takes place at the kinetic
+turnover point. Because the friction is a reflection of the microscopic degrees
+of freedom acting on the order parameter of the black hole, the turnover and
+the corresponding fluctuations of the phase transition kinetics can be used to
+probe the black hole microstructure.",2102.09439v1
+2021-02-25,Energy Decay of some boundary coupled systems involving wave$\backslash$ Euler-Bernoulli beam with one locally singular fractional Kelvin-Voigt damping,"In this paper, we investigate the energy decay of hyperbolic systems of
+wave-wave, wave-Euler- Bernoulli beam and beam-beam types. The two equations
+are coupled through boundary connection with only one localized non-smooth
+fractional Kelvin-Voigt damping. First, we reformulate each system into an
+augmented model and using a general criteria of Arendt-Batty, we prove that our
+models are strongly stable. Next, by using frequency domain approach, combined
+with multiplier technique and some interpolation inequalities, we establish
+different types of polynomial energy decay rate which depends on the order of
+the fractional derivative and the type of the damped equation in the system.",2102.12732v2
+2021-03-01,Fluid-plate interaction under periodic forcing,"The motion of a thin elastic plate interacting with a viscous fluid is
+investigated. A periodic force acting on the plate is considered, which in a
+setting without damping could lead to a resonant response. The interaction with
+the viscous fluid provides a damping mechanism due to the energy dissipation in
+the fluid. Moreover, an internal damping mechanism in the plate is introduced.
+In this setting, we show that the periodic forcing leads to a time-periodic
+(non-resonant) solution. We employ the Navier-Stokes and the Kirchhoff-Love
+plate equation in a periodic cell structure to model the motion of the viscous
+fluid and the elastic plate, respectively. Maximal Lp regularity for the
+linearized system is established in a framework of time-periodic function
+spaces. Existence of a solution to the fully nonlinear system is subsequently
+shown with a fixed-point argument.",2103.00795v1
+2021-03-25,Nonlinear inviscid damping and shear-buoyancy instability in the two-dimensional Boussinesq equations,"We investigate the long-time properties of the two-dimensional inviscid
+Boussinesq equations near a stably stratified Couette flow, for an initial
+Gevrey perturbation of size $\varepsilon$. Under the classical Miles-Howard
+stability condition on the Richardson number, we prove that the system
+experiences a shear-buoyancy instability: the density variation and velocity
+undergo an $O(t^{-1/2})$ inviscid damping while the vorticity and density
+gradient grow as $O(t^{1/2})$. The result holds at least until the natural,
+nonlinear timescale $t \approx \varepsilon^{-2}$. Notice that the density
+behaves very differently from a passive scalar, as can be seen from the
+inviscid damping and slower gradient growth. The proof relies on several
+ingredients: (A) a suitable symmetrization that makes the linear terms amenable
+to energy methods and takes into account the classical Miles-Howard spectral
+stability condition; (B) a variation of the Fourier time-dependent energy
+method introduced for the inviscid, homogeneous Couette flow problem developed
+on a toy model adapted to the Boussinesq equations, i.e. tracking the potential
+nonlinear echo chains in the symmetrized variables despite the vorticity
+growth.",2103.13713v1
+2021-03-31,Research of Damped Newton Stochastic Gradient Descent Method for Neural Network Training,"First-order methods like stochastic gradient descent(SGD) are recently the
+popular optimization method to train deep neural networks (DNNs), but
+second-order methods are scarcely used because of the overpriced computing cost
+in getting the high-order information. In this paper, we propose the Damped
+Newton Stochastic Gradient Descent(DN-SGD) method and Stochastic Gradient
+Descent Damped Newton(SGD-DN) method to train DNNs for regression problems with
+Mean Square Error(MSE) and classification problems with Cross-Entropy
+Loss(CEL), which is inspired by a proved fact that the hessian matrix of last
+layer of DNNs is always semi-definite. Different from other second-order
+methods to estimate the hessian matrix of all parameters, our methods just
+accurately compute a small part of the parameters, which greatly reduces the
+computational cost and makes convergence of the learning process much faster
+and more accurate than SGD. Several numerical experiments on real datesets are
+performed to verify the effectiveness of our methods for regression and
+classification problems.",2103.16764v1
+2021-04-08,Landau Damping in the Transverse Modulational Dynamics of Co-Propagating Light and Matter Beams,"The optomechanical coupling and transverse stability of a co-propagating
+monochromatic electromagnetic wave and mono-energetic beam of two-level atoms
+is investigated in the collisionless regime. The coupled dynamics are studied
+through a Landau stability analysis of the coupled gas- kinetic and paraxial
+wave equations, including the effect of the electronic nonlinearity. The
+resulting dispersion relation captures the interaction of kinetic and
+saturation effects and shows that for blue detuning the combined nonlinear
+interaction is unstable below a critical wavenumber which reduces to the result
+of Bespalov and Talanov in the limit of a negligible kinetic nonlinearity. For
+red detuning we find that under a saturation parameter threshold exists whereby
+the system stabilizes unconditionally. With negligible saturation, an
+optomechanical form of Landau damping stabilizes all wavenumbers above a
+critical wavenumber determined by the combined strength of the kinetic and
+refractive optomechanical feedback. The damping is mediated primarily by atoms
+traveling along the primary diagonals of the Talbot carpet.",2104.04100v1
+2021-04-15,Simulating cosmological supercooling with a cold atom system II,"We perform an analysis of the supercooled state in an analogue of an early
+universe phase transition based on a one dimensional, two-component Bose gas
+with time-dependent interactions. We demonstrate that the system behaves in the
+same way as a thermal, relativistic Bose gas undergoing a first order phase
+transition. We propose a way to prepare the state of the system in the
+metastable phase as an analogue to supercooling in the early universe. While we
+show that parametric resonances in the system can be suppressed by thermal
+damping, we find that the theoretically estimated thermal damping in our model
+is too weak to suppress the resonances for realistic experimental parameters.
+However, we propose that experiments to investigate the effective damping rate
+in experiments would be worthwhile.",2104.07428v1
+2021-05-04,Linear response theory and damped modes of stellar clusters,"Because all stars contribute to its gravitational potential, stellar clusters
+amplify perturbations collectively. In the limit of small fluctuations, this is
+described through linear response theory, via the so-called response matrix.
+While the evaluation of this matrix is somewhat straightforward for unstable
+modes (i.e. with a positive growth rate), it requires a careful analytic
+continuation for damped modes (i.e. with a negative growth rate). We present a
+generic method to perform such a calculation in spherically symmetric stellar
+clusters. When applied to an isotropic isochrone cluster, we recover the
+presence of a low-frequency weakly damped $\ell = 1$ mode. We finally use a set
+of direct $N$-body simulations to test explicitly this prediction through the
+statistics of the correlated random walk undergone by a cluster's density
+centre.",2105.01371v1
+2021-05-10,Passivity-based control of mechanical systems with linear damping identification,"We propose a control approach for a class of nonlinear mechanical systems to
+stabilize the system under study while ensuring that the oscillations of the
+transient response are reduced. The approach is twofold: (i) we apply our
+technique for linear viscous damping identification of the system to improve
+the accuracy of the selected control technique, and (ii) we implement a
+passivity-based controller to stabilize and reduce the oscillations by
+selecting the control parameters properly in accordance with the identified
+damping. Moreover, we provide an analysis for a particular passivity-based
+control approach that has been shown successfully for reducing such
+oscillations. Also, we validate the methodology by implementing it
+experimentally in a planar manipulator.",2105.04324v4
+2021-05-26,Decay dynamics of Localised Surface Plasmons: damping of coherences and populations of the oscillatory plasmon modes,"Properties of plasmonic materials are associated with surface plasmons - the
+electromagnetic excitations coupled to coherent electron charge density
+oscillations on a metal/dielectric interface. Although decay of such
+oscillations cannot be avoided, there are prospects for controlling plasmon
+damping dynamics. In spherical metal nanoparticles (MNPs) the basic properties
+of Localized Surface Plasmons (LSPs) can be controlled with their radius. The
+present paper handles the link between the size-dependent description of LSP
+properties derived from the dispersion relation based on Maxwell's equations
+and the quantum picture in which MNPs are treated as ""quasi-particles"". Such
+picture, based on the reduced density-matrix of quantum open systems ruled by
+the master equation in the Lindblad form, enables to distinguish between
+damping processes of populations and coherences of multipolar plasmon
+oscillatory states and to establish the intrinsic relations between the rates
+of these processes, independently of the size of MNP. The impact of the
+radiative and the nonradiative energy dissipation channels is discussed.",2105.12463v1
+2021-06-05,The electron acoustic waves in plasmas with two kappa-distributed electrons at the same temperatures and immobile ions,"The linear electron acoustic waves propagating in plasmas with two
+kappa-distributed electrons and stationary ions are investigated. The
+temperatures of the two electrons are assumed to be the same, but the kappa
+indices are not. It shows that if one kappa index is small enough and the other
+one is large enough, a weak damping regime of the electron acoustic waves
+exists. The dispersions and damping rates are numerically studied. The
+parameter spaces for the weakly damped electron acoustic waves are analyzed.
+Moreover, the electron acoustic waves in the present model are compared with
+those in other models, especially the plasmas with two-temperature electrons.
+At last, we perform Vlasov-Poisson simulations to verify the theory.",2106.02910v2
+2021-06-18,Global existence and asymptotic behavior for semilinear damped wave equations on measure spaces,"This paper is concerned with the semilinear damped wave equation on a measure
+space with a self-adjoint operator, instead of the standard Laplace operator.
+Under a certain decay estimate on the corresponding heat semigroup, we
+establish the linear estimates which generalize the so-called Matsumura
+estimates, and prove the small data global existence of solutions to the damped
+wave equation based on the linear estimates. Our approach is based on a direct
+spectral analysis analogous to the Fourier analysis. The self-adjoint operators
+treated in this paper include some important examples such as the Laplace
+operators on Euclidean spaces, the Dirichlet Laplacian on an arbitrary open
+set, the Robin Laplacian on an exterior domain, the Schr\""odinger operator, the
+elliptic operator, the Laplacian on Sierpinski gasket, and the fractional
+Laplacian.",2106.10322v3
+2021-06-21,On the small time asymptotics of stochastic Ladyzhenskaya-Smagorinsky equations with damping perturbed by multiplicative noise,"The Ladyzhenskaya-Smagorinsky equations model turbulence phenomena, and are
+given by $$\frac{\partial \boldsymbol{u}}{\partial t}-\mu
+\mathrm{div}\left(\left(1+|\nabla\boldsymbol{u}|^2\right)^{\frac{p-2}{2}}\nabla\boldsymbol{u}\right)+(\boldsymbol{u}\cdot\nabla)\boldsymbol{u}+\nabla
+p=\boldsymbol{f}, \ \nabla\cdot\boldsymbol{u}=0,$$ for $p\geq 2,$ in a bounded
+domain $\mathcal{O}\subset\mathbb{R}^d$ ($2\leq d\leq 4$). In this work, we
+consider the stochastic Ladyzhenskaya-Smagorinsky equations with the damping
+$\alpha\boldsymbol{u}+\beta|\boldsymbol{u}|^{r-2}\boldsymbol{u},$ for $r\geq 2$
+($\alpha,\beta\geq 0$), subjected to multiplicative Gaussian noise. We show the
+local monotoincity ($p\geq \frac{d}{2}+1,\ r\geq 2$) as well as global
+monotonicity ($p\geq 2,\ r\geq 4$) properties of the linear and nonlinear
+operators, which along with an application of stochastic version of
+Minty-Browder technique imply the existence of a unique pathwise strong
+solution. Then, we discuss the small time asymptotics by studying the effect of
+small, highly nonlinear, unbounded drifts (small time large deviation
+principle) for the stochastic Ladyzhenskaya-Smagorinsky equations with damping.",2106.10861v1
+2021-06-23,Improved convergence rates and trajectory convergence for primal-dual dynamical systems with vanishing damping,"In this work, we approach the minimization of a continuously differentiable
+convex function under linear equality constraints by a second-order dynamical
+system with asymptotically vanishing damping term. The system is formulated in
+terms of the augmented Lagrangian associated to the minimization problem. We
+show fast convergence of the primal-dual gap, the feasibility measure, and the
+objective function value along the generated trajectories. In case the
+objective function has Lipschitz continuous gradient, we show that the
+primal-dual trajectory asymptotically weakly converges to a primal-dual optimal
+solution of the underlying minimization problem. To the best of our knowledge,
+this is the first result which guarantees the convergence of the trajectory
+generated by a primal-dual dynamical system with asymptotic vanishing damping.
+Moreover, we will rediscover in case of the unconstrained minimization of a
+convex differentiable function with Lipschitz continuous gradient all
+convergence statements obtained in the literature for Nesterov's accelerated
+gradient method.",2106.12294v1
+2021-07-01,On behavior of solutions to a Petrovsky equation with damping and variable-exponent source,"This paper deals with the following Petrovsky equation with damping and
+nonlinear source \[u_{tt}+\Delta^2 u-M(\|\nabla u\|_2^2)\Delta u-\Delta
+u_t+|u_t|^{m(x)-2}u_t=|u|^{p(x)-2}u\] under initial-boundary value conditions,
+where $M(s)=a+ bs^\gamma$ is a positive $C^1$ function with parameters
+$a>0,~b>0,~\gamma\geq 1$, and $m(x),~p(x)$ are given measurable functions. The
+upper bound of the blow-up time is derived for low initial energy using the
+differential inequality technique. For $m(x)\equiv2$, in particular, the upper
+bound of the blow-up time is obtained by the combination of Levine's concavity
+method and some differential inequalities under high initial energy. In
+addition, by making full use of the strong damping, the lower bound of the
+blow-up time is discussed. Moreover, the global existence of solutions and an
+energy decay estimate are presented by establishing some energy estimates and
+by exploiting a key integral inequality.",2107.00273v2
+2021-07-21,A combined volume penalization / selective frequency damping approach for immersed boundary methods applied to high-order schemes,"There has been an increasing interest in developing efficient immersed
+boundary method (IBM) based on Cartesian grids, recently in the context of
+high-order methods. IBM based on volume penalization is a robust and easy to
+implement method to avoid body-fitted meshes and has been recently adapted to
+high order discretisations (Kou et al., 2021). This work proposes an
+improvement over the classic penalty formulation for flux reconstruction high
+order solvers. We include a selective frequency damping (SFD) approach
+(Aakervik et al., 2006) acting only inside solid body defined through the
+immersed boundary masking, to damp spurious oscillations. An encapsulated
+formulation for the SFD method is implemented, which can be used as a wrapper
+around an existing time-stepping code. The numerical properties have been
+studied through eigensolution analysis based on the advection equation. These
+studies not only show the advantages of using the SFD method as an alternative
+of the traditional volume penalization, but also show the favorable properties
+of combining both approaches. This new approach is then applied to the
+Navier-Stokes equation to simulate steady flow past an airfoil and unsteady
+flow past a circular cylinder. The advantages of the SFD method in providing
+improved accuracy are reported.",2107.10177v1
+2021-07-25,Dispatch of Virtual Inertia and Damping: Numerical Method with SDP and ADMM,"Power grids are evolving toward 100% renewable energy interfaced by
+inverters. Virtual inertia and damping provided by inverters are essential to
+synchronism and frequency stability of future power grids. This paper
+numerically addresses the problem of dispatch of virtual inertia and damping
+(DID) among inverters in the transmission network. The DID problem is first
+formulated as a nonlinear program (NLP) by the Radua collocation method which
+is flexible to handle various types of disturbances and bounds constraints.
+Since the NLP of DID is highly non-convex, semi-definite programming (SDP)
+relaxation for the NLP is further derived to tackle the non-convexity, followed
+by its sparsity being exploited hierarchically based on chordality of graphs to
+seek enhancement of computational efficiency. Considering high dimension and
+inexactness of the SDP relaxation, a feasibility-embedded distributed approach
+is finally proposed under the framework of alternating direction method of
+multipliers (ADMM), which achieves parallel computing and solution feasibility
+regarding the original NLP. Numerical simulations carried out for five test
+power systems demonstrate the proposed method and necessity of DID.",2107.11764v1
+2021-08-09,Damping perturbation based time integration asymptotic method for structural dynamics,"The light damping hypothesis is usually assumed in structural dynamics since
+dissipative forces are in general weak with respect to inertial and elastic
+forces. In this paper a novel numerical method of time integration based on the
+artificial perturbation of damping is proposed. The asymptotic expansion of the
+transient response results in an infinite series which can be summed, leading
+to a well-defined explicit iterative step-by-step scheme. Conditions for
+convergence are rigorously analyzed, enabling the determination of the
+methodology boundaries in form of maximum time step. The numerical properties
+of the iterative scheme, i.e. stability, accuracy and computational effort are
+also studied in detail. The approach is validated with two numerical examples,
+showing a high accuracy and computational efficiency relative to other methods.",2108.03813v1
+2021-09-22,Antibunching via cooling by heating,"We investigate statistics of the photon (phonon) field undergoing linear and
+nonlinear damping processes. An effective two-photon (phonon) nonlinear
+""cooling by heating"" process is realized from linear damping by spectral
+filtering of the heat baths present in the system. This cooling process driven
+by incoherent quantum thermal noise can create quantum states of the photon
+field. In fact, for high temperatures of the spectrally filtered heat baths,
+sub-Poissonian statistics with strong antibunching in the photon (phonon) field
+are reported. This notion of the emergence and control of quantumness by
+incoherent thermal quantum noise is applied to a quantum system comprising of a
+two-level system and a harmonic oscillator or analogous optomechanical setting.
+Our analysis may provide a promising direction for the preparation and
+protection of quantum features via nonlinear damping that can be controlled
+with incoherent thermal quantum noise.",2109.10516v2
+2021-10-13,Tutorial on stochastic systems,"In this tutorial, three examples of stochastic systems are considered: A
+strongly-damped oscillator, a weakly-damped oscillator and an undamped
+oscillator (integrator) driven by noise. The evolution of these systems is
+characterized by the temporal correlation functions and spectral densities of
+their displacements, which are determined and discussed. Damped oscillators
+reach steady stochastic states. Their correlations are decreasing functions of
+the difference between the sample times and their spectra have peaks near their
+resonance frequencies. An undamped oscillator never reaches a steady state. Its
+energy increases with time and its spectrum is sharply peaked at low
+frequencies. The required mathematical methods and physical concepts are
+explained on a just-in-time basis, and some theoretical pitfalls are mentioned.
+The insights one gains from studies of oscillators can be applied to a wide
+variety of physical systems, such as atom and semiconductor lasers, which will
+be discussed in a subsequent tutorial.",2110.06966v1
+2021-10-18,Structured vector fitting framework for mechanical systems,"In this paper, we develop a structure-preserving formulation of the
+data-driven vector fitting algorithm for the case of modally damped mechanical
+systems. Using the structured pole-residue form of the transfer function of
+modally damped second-order systems, we propose two possible structured
+extensions of the barycentric formula of system transfer functions. Integrating
+these new forms within the classical vector fitting algorithm leads to the
+formulation of two new algorithms that allow the computation of modally damped
+mechanical systems from data in a least squares fashion. Thus, the learned
+model is guaranteed to have the desired structure. We test the proposed
+algorithms on two benchmark models.",2110.09220v1
+2021-10-27,Integrability and solvability of polynomial Liénard differential systems,"We provide the necessary and sufficient conditions of Liouvillian
+integrability for Li\'{e}nard differential systems describing nonlinear
+oscillators with a polynomial damping and a polynomial restoring force. We
+prove that Li\'{e}nard differential systems are not Darboux integrable
+excluding subfamilies with certain restrictions on the degrees of the
+polynomials arising in the systems. We demonstrate that if the degree of a
+polynomial responsible for the restoring force is greater than the degree of a
+polynomial producing the damping, then a generic Li\'{e}nard differential
+system is not Liouvillian integrable with the exception of linear Li\'{e}nard
+systems. However, for any fixed degrees of the polynomials describing the
+damping and the restoring force we present subfamilies possessing Liouvillian
+first integrals. As a by-product of our results, we find a number of novel
+Liouvillian integrable subfamilies. In addition, we study the existence of
+non-autonomous Darboux first integrals and non-autonomous Jacobi last
+multipliers with a time-dependent exponential factor.",2110.14306v2
+2021-10-28,Global Solution to the Vacuum Free Boundary Problem with Physical Singularity of Compressible Euler Equations with Damping and Gravity,"The global existence of smooth solutions to the vacuum free boundary problem
+with physical singularity of compressible Euler equations with damping and
+gravity is proved in space dimensions $n=1, 2, 3$, for the initial data being
+small perturbations of the stationary solution. Moreover, the exponential decay
+of the velocity is obtained for $n=1, 2, 3$. The exponentially fast convergence
+of the density and vacuum boundary to those of the stationary solution is shown
+for $n=1$, and it is proved for $n=2, 3$ that they stay close to those of the
+stationary solution if they do so initially. The proof is based on the weighted
+estimates of both hyperbolic and parabolic types with weights capturing the
+singular behavior of higher-order normal derivatives near vacuum states,
+exploring the balance between the physical singularity which pushes the vacuum
+boundary outwards and the effect of gravity which pulls it inwards, and the
+dissipation of the frictional damping. The results obtained in this paper are
+the first ones on the global existence of solutions to the vacuum free boundary
+problems of inviscid compressible fluids with the non-expanding background
+solutions. Exponentially fast convergence when the vacuum state is involved
+discovered in this paper is a new feature of the problem studied.",2110.14909v1
+2021-10-29,Spinons and damped phonons in spin-1/2 quantum-liquid Ba$_{4}$Ir${}_3$O${}_{10}$ observed by Raman scattering,"In spin-1/2 Mott insulators, non-magnetic quantum liquid phases are often
+argued to arise when the system shows no magnetic ordering, but identifying
+positive signatures of these phases or related spinon quasiparticles can be
+elusive. Here we use Raman scattering to provide three signatures for spinons
+in a possible spin-orbit quantum liquid material Ba${}_4$Ir${}_3$O${}_{10}$:
+(1) A broad hump, which we show can arise from Luttinger Liquid spinons in
+Raman with parallel photon polarizations normal to 1D chains; (2) Strong phonon
+damping from phonon-spin coupling via the spin-orbit interaction; and (3) the
+absence of (1) and (2) in the magnetically ordered phase that is produced when
+2% of Ba is substituted by Sr
+((Ba${}_{0.98}$Sr${}_{0.02}$)${}_4$Ir${}_3$O${}_{10}$). The phonon damping via
+itinerant spinons seen in this quantum-liquid insulator suggests a new
+mechanism for enhancing thermoelectricity in strongly correlated conductors,
+through a neutral quantum liquid that need not affect electronic transport.",2110.15916v1
+2021-11-03,Pointwise space-time estimates of two-phase fluid model in dimension three,"In this paper, we investigate the pointwise space-time behavior of two-phase
+fluid model derived by Choi \cite{Choi} [SIAM J. Math. Anal., 48(2016), pp.
+3090-3122], which is the compressible damped Euler equations coupled with
+compressible Naiver-Stokes equations. Based on Green's function method together
+with frequency analysis and nonlinear coupling of different wave patterns, it
+shows that both of two densities and momentums obey the generalized Huygens'
+principle as the compressible Navier-Stokes equations \cite{LW}, however, it is
+different from the compressible damped Euler equations \cite{Wang2}. The main
+contributions include seeking suitable combinations to avoid the singularity
+from the Hodge decomposition in the low frequency part of the Green's function,
+overcoming the difficulty of the non-conservation arising from the damped
+mechanism of the system, and developing the detailed description of the
+singularities in the high frequency part of the Green's function. Finally, as a
+byproduct, we extend $L^2$-estimate in \cite{Wugc} [SIAM J. Math. Anal.,
+52(2020), pp. 5748-5774] to $L^p$-estimate with $p>1$.",2111.01987v1
+2021-11-09,Turbulent cascades for a family of damped Szegö equations,"In this paper, we study the transfer of energy from low to high frequencies
+for a family of damped Szeg\""o equations. The cubic Szeg\""o equation has been
+introduced as a toy model for a totally non-dispersive degenerate Hamiltonian
+equation. It is a completely integrable system which develops growth of high
+Sobolev norms, detecting transfer of energy and hence cascades phenomena.
+  Here, we consider a two-parameter family of variants of the cubic Szeg\""o
+equation and prove that adding a damping term unexpectedly promotes the
+existence of turbulent cascades. Furthermore, we give a panorama of the
+dynamics for such equations on a six-dimensional submanifold.",2111.05247v1
+2021-11-22,Global well-posedness for a generalized Keller-Segel system with degenerate dissipation and mixing,"We study the mixing effect for a generalized Keller-Segel system with
+degenerate dissipation and advection by a weakly mixing. Here the attractive
+operator has weak singularity, namely, the negative derivative appears in the
+nonlinear term by singular integral. Without advection, the solution of
+equation blows up in finite time. We show that the global well-posedness of
+solution with large advection. Since dissipation term degenerate into the
+damping, the enhanced dissipation effect of mixing no longer occurs, we prove
+that the mixing effect can weak the influence of nonlinear term. In this case,
+the mixing effect is similar with inviscid damping of shear flow. Combining to
+the mixing effect and damping effect of degenerate dissipation, the global
+$L^\infty$ estimate of solution is established.",2111.11083v1
+2021-11-26,Transition from order to chaos in reduced quantum dynamics,"We study a damped kicked top dynamics of a large number of qubits ($N
+\rightarrow \infty$) and focus on an evolution of a reduced single-qubit
+subsystem. Each subsystem is subjected to the amplitude damping channel
+controlled by the damping constant $r\in [0,1]$, which plays the role of the
+single control parameter. In the parameter range for which the classical
+dynamics is chaotic, while varying $r$ we find the universal period-doubling
+behavior characteristic to one-dimensional maps: period-two dynamics starts at
+$r_1 \approx 0.3181$, while the next bifurcation occurs at $ r_2 \approx
+0.5387$. In parallel with period-four oscillations observed for $r \leq r_3
+\approx 0.5672$, we identify a secondary bifurcation diagram around $r\approx
+0.544$, responsible for a small-scale chaotic dynamics inside the attractor.
+The doubling of the principal bifurcation tree continues until $r \leq
+r_{\infty} \sim 0.578$, which marks the onset of the full scale chaos
+interrupted by the windows of the oscillatory dynamics corresponding to the
+Sharkovsky order.",2111.13477v1
+2021-12-06,"Damped physical oscillators, temperature and chemical clocks","The metaphor of a clock in physics describes near-equilibrium reversible
+phenomena such as an oscillating spring. It is surprising that for chemical and
+biological clocks the focus has been exclusively on the far-from-equilibrium
+dissipative processes. We show here that one can represent chemical
+oscillations (the Lotka-Volterra system and the Brusselator) by equations
+analogous to Onsager's phenomenological equations when the condition of the
+reciprocal relations, i.e. the symmetry in the coupling of thermodynamic forces
+to fluxes is relaxed and antisymmetric contributions are permitted. We compare
+these oscillations to damped oscillators in physics (e.g., springs, coupled
+springs and electrical circuits) which are represented by similar equations.
+Onsager's equations and harmonic Hamiltonian systems are shown to be limiting
+cases of a more general formalism.
+  The central element of un-damped physical oscillations is the conservation of
+entropy which unavoidably results in reversible temperature oscillations. Such
+temperature oscillations exist in springs and electrical LC-circuits, but have
+among others also been found in the oscillating Belousov-Zhabotinsky reaction,
+in oscillations of yeast cells, and during the nervous impulse. This suggests
+that such oscillations contain reversible entropy-conserving elements, and that
+physical and chemical clocks may be more similar than expected.",2112.03083v1
+2021-12-10,Existence of Zero-damped Quasinormal Frequencies for Nearly Extremal Black Holes,"It has been observed that many spacetimes which feature a near-extremal
+horizon exhibit the phenomenon of zero-damped modes. This is characterised by
+the existence of a sequence of quasinormal frequencies which all converge to
+some purely imaginary number $i\alpha$ in the extremal limit and cluster in a
+neighbourhood of the line $\Im s=\alpha$. In this paper, we establish that this
+property is present for the conformal Klein-Gordon equation on a
+Reissner-Nordstr\""om-de Sitter background. This follows from a similar result
+that we prove for a class of spherically symmetric black hole spacetimes with a
+cosmological horizon. We also show that the phenomenon of zero-damped modes is
+stable to perturbations that arise through adding a potential.",2112.05669v3
+2021-12-22,Quantifying Spin-Orbit Torques in Antiferromagnet/Heavy Metal Heterostructures,"The effect of spin currents on the magnetic order of insulating
+antiferromagnets (AFMs) is of fundamental interest and can enable new
+applications. Toward this goal, characterizing the spin-orbit torques (SOT)
+associated with AFM/heavy metal (HM) interfaces is important. Here we report
+the full angular dependence of the harmonic Hall voltages in a predominantly
+easy-plane AFM, epitaxial c-axis oriented $\alpha$-Fe$_2$O$_3$ films, with an
+interface to Pt. By modeling the harmonic Hall signals together with the
+$\alpha$-Fe$_2$O$_3$ magnetic parameters, we determine the amplitudes of
+field-like and damping-like SOT. Out-of-plane field scans are shown to be
+essential to determining the damping-like component of the torques. In contrast
+to ferromagnetic/heavy metal heterostructures, our results demonstrate that the
+field-like torques are significantly larger than the damping-like torques,
+which we correlate with the presence of a large imaginary component of the
+interface spin-mixing conductance. Our work demonstrates a direct way of
+characterizing SOT in AFM/HM heterostructures.",2112.12238v1
+2022-01-04,Focusing of nonlinear eccentric waves in astrophysical discs. II. Excitation and damping of tightly-wound waves,"In this paper I develop a nonlinear theory of tightly-wound (highly twisted)
+eccentric waves in astrophysical discs, based on the averaged Lagrangian method
+of Whitham. Viscous dissipation is included in the theory by use of a
+pseudo-Lagrangian. This work is an extension of the theory developed by Lee \&
+Goodman to 3D discs, with the addition of viscosity. I confirm that linear
+tightly-wound eccentric waves are overstable and are excited by the presence of
+a shear viscosity and show this persists for weakly nonlinear waves. I find the
+waves are damped by shear viscosity when the wave become sufficiently
+nonlinear, a result previously found in particulate discs. Additionally I
+compare the results of this model to recent simulations of eccentric waves
+propagating in the inner regions of black hole discs and show that an ingoing
+eccentric wave can be strongly damped near the marginally stable orbit,
+resulting in a nearly circular disc with a strong azimuthal variation in the
+disc density.",2201.01156v1
+2022-01-12,Local Well-Posedness of the Gravity-Capillary Water Waves System in the Presence of Geometry and Damping,"We consider the gravity-capillary water waves problem in a domain $\Omega_t
+\subset \mathbb{T} \times \mathbb{R}$ with substantial geometric features.
+Namely, we consider a variable bottom, smooth obstacles in the flow and a
+constant background current. We utilize a vortex sheet model introduced by
+Ambrose, et. al. in arXiv:2108.01786. We show that the water waves problem is
+locally-in-time well-posed in this geometric setting and study the lifespan of
+solutions. We then add a damping term and derive evolution equations that
+account for the damper. Ultimately, we show that the same well-posedness and
+lifespan results apply to the damped system. We primarily utilize energy
+methods.",2201.04713v2
+2022-02-04,"Finite-temperature plasmons, damping and collective behavior for $α-\mathcal{T}_3$ model","We have conducted a thorough theoretical and numerical investigation of the
+electronic susceptibility, polarizability, plasmons, their damping rates, as
+well as the static screening in pseudospin-1 Dirac cone materials with a flat
+band, or for a general $\alpha - \mathcal{T}_3$ model, at finite temperatures.
+This includes calculating the polarization function, plasmon dispersions and
+their damping rates at arbitrary temperatures and obtaining analytical
+approximations the long wavelength limit, low and high temperatures. We
+demonstrate that the integral transformation of the polarization function
+cannot be used directly for a dice lattice revealing some fundamental
+properties and important applicability limits of the flat band dispersions
+model. At $k_B T \ll E_F$, the largest temperature-induced change of the
+polarization function and plasmons comes from the mismatch between the chemical
+potential and the Fermi energy. We have also obtained a series of closed-form
+semi-analytical expressions for the static limit of the polarization function
+of an arbitrary $\alpha - \mathcal{T}_3$ material at any temperature with exact
+analytical formulas for the high, low and zero temperature limits which is of
+tremendous importance for all types of transport and screening calculations for
+the flat band Dirac materials.",2202.01945v1
+2022-02-04,Enhancing the Formation of Wigner Negativity in a Kerr Oscillator via Quadrature Squeezing,"Motivated by quantum experiments with nanomechanical systems, the evolution
+of a Kerr oscillator with focus on creation of states with a negative Wigner
+function is investigated. Using the phase space formalism, results are
+presented that demonstrate an asymptotic behavior in the large squeezing regime
+for the negativity of a squeezed vacuum state under unitary evolution. The
+analysis and model are extended to squeezed vacuum states of open systems,
+adding the decoherence effects of damping and dephasing. To increase
+experimental relevance, the regime of strong damping is considered. These
+effects are investigated, yielding similar asymptotic results for the behavior
+of these effects in the large squeezing regime. Combining these results, it is
+shown that a weak nonlinearity as compared to damping may be improved by
+increasing the squeezing of the initial state. It is also shown that this may
+be done without exacerbating the effects of dephasing.",2202.02285v1
+2022-02-11,"Spin stiffness, spectral weight, and Landau damping of magnons in metallic spiral magnets","We analyze the properties of magnons in metallic electron systems with spiral
+magnetic order. Our analysis is based on the random phase approximation for the
+susceptibilities of tight binding electrons with a local Hubbard interaction in
+two or three dimensions. We identify three magnon branches from poles in the
+susceptibilities, one associated with in-plane, the other two associated with
+out-of-plane fluctuations of the spiral order parameter. We derive general
+expressions for the spin stiffnesses and the spectral weights of the magnon
+modes, from which also the magnon velocities can be obtained. Moreover, we
+determine the size of the decay rates of the magnons due to Landau damping.
+While the decay rate of the in-plane mode is of the order of its excitation
+energy, the decay rate of the out-of-plane mode is smaller so that these modes
+are asymptotically stable excitations even in the presence of Landau damping.",2202.05660v1
+2022-04-01,Effect of interfacial spin mixing conductance on gyromagnetic ratio of Gd substituted Y$_{3}$Fe$_{5}$O$_{12}$,"Due to its low intrinsic damping, Y$_3$Fe$_5$O$_{12}$ and its substituted
+variations are often used for ferromagnetic layer at spin pumping experiment.
+Spin pumping is an interfacial spin current generation in the interface of
+ferromagnet and non-magnetic metal, governed by spin mixing conductance
+parameter $G^{\uparrow\downarrow}$. $G^{\uparrow\downarrow}$ has been shown to
+enhance the damping of the ferromagnetic layer. The theory suggested that the
+effect of $G^{\uparrow\downarrow}$ on gyromagnetic ratio only come from its
+negligible imaginary part. In this article, we show that the different damping
+of ferrimagnetic lattices induced by $G^{\uparrow\downarrow}$ can affect the
+gyromagnetic ratio of Gd-substituted Y$_3$Fe$_5$O$_{12}$.",2204.00310v1
+2022-04-04,A Vanka-based parameter-robust multigrid relaxation for the Stokes-Darcy Brinkman problems,"We propose a block-structured multigrid relaxation scheme for solving the
+Stokes-Darcy Brinkman equations discretized by the marker and cell scheme. An
+element-based additive Vanka smoother is used to solve the corresponding
+shifted Laplacian operator. Using local Fourier analysis, we present the
+stencil for the additive Vanka smoother and derive an optimal smoothing factor
+for Vanka-based Braess-Sarazin relaxation for the Stokes-Darcy Brinkman
+equations. Although the optimal damping parameter is dependent on meshsize and
+physical parameter, it is very close to one. Numerical results of two-grid and
+V(1,1)-cycle are presented, which show high efficiency of the proposed
+relaxation scheme and its robustness to physical parameters and the meshsize.
+Using a damping parameter equal to one gives almost the same results as these
+for the optimal damping parameter at a lower computational overhead.",2204.01237v1
+2022-04-19,Blow-up and lifespan estimate for wave equations with critical damping term of space-dependent type related to Glassey conjecture,"The main purpose of the present paper is to study the blow-up problem of the
+wave equation with space-dependent damping in the \textit{scale-invariant case}
+and time derivative nonlinearity with small initial data. Under appropriate
+initial data which are compactly supported, by using a test function method and
+taking into account the effect of the damping term
+($\frac{\mu}{\sqrt{1+|x|^2}}u_t$), we provide that in higher dimensions the
+blow-up region is given by $p \in (1, p_G(N+\mu)]$ where $p_G(N)$ is the
+Glassey exponent. Furthermore, we shall establish a blow-up region, independent
+of $\mu$ given by $p\in (1, 1+\frac{2}{N}),$ for appropriate initial data in
+the energy space with noncompact support.",2204.09156v1
+2022-04-28,Strong coupling of quantum emitters and the exciton polariton in MoS$_2$ nanodisks,"As a quasiparticle formed by light and excitons in semiconductors, the
+exciton-polariton (EP) as a quantum bus is promising for the development of
+quantum interconnect devices at room temperature. However, the significant
+damping of EPs in the material generally causes a loss of quantum information.
+We propose a mechanism to overcome the destructive effect of a damping EP on
+its mediated correlation dynamics of quantum emitters (QEs). Via an
+investigation of the near-field coupling between two QEs and the EP in a
+monolayer MoS$_{2}$ nanodisk, we find that, with the complete dissipation of
+the QEs efficiently avoided, a persistent quantum correlation between the QEs
+can be generated and stabilized even to their steady state. This is due to the
+fact that, with upon decreasing the QE-MoS$_2$ distance, the QEs become so
+hybridized with the EP that one or two bound states are formed between them.
+Our result supplies a useful way to avoid the destructive impact of EP damping,
+and it refreshes our understanding of the light-matter interaction in absorbing
+medium.",2204.13383v2
+2022-05-09,Scalable all-optical cold damping of levitated nanoparticles,"The field of levitodynamics has made significant progress towards controlling
+and studying the motion of a levitated nanoparticle. Motional control relies on
+either autonomous feedback via a cavity or measurement-based feedback via
+external forces. Recent demonstrations of measurement-based ground-state
+cooling of a single nanoparticle employ linear velocity feedback, also called
+cold damping, and require the use of electrostatic forces on charged particles
+via external electrodes. Here we introduce a novel all-optical cold damping
+scheme based on spatial modulation of the trap position that is scalable to
+multiple particles. The scheme relies on using programmable optical tweezers to
+provide full independent control over trap frequency and position of each
+tweezer. We show that the technique cools the center-of-mass motion of
+particles down to $17\,$mK at a pressure of $2 \times 10^{-6}\,$mbar and
+demonstrate its scalability by simultaneously cooling the motion of two
+particles. Our work paves the way towards studying quantum interactions between
+particles, achieving 3D quantum control of particle motion without cavity-based
+cooling, electrodes or charged particles, and probing multipartite entanglement
+in levitated optomechanical systems.",2205.04455v1
+2022-06-08,Thermal ion kinetic effects and Landau damping in fishbone modes,"The kinetic-MHD hybrid simulation approach for macroscopic instabilities in
+plasmas can be extended to include the kinetic effects of both thermal ions and
+energetic ions. The new coupling scheme includes synchronization of density and
+parallel velocity between thermal ions and MHD, in addition to pressure
+coupling, to ensure the quasineutrality condition and avoid numerical errors.
+The new approach has been implemented in the kinetic-MHD code M3D-C1-K, and was
+used to study the thermal ion kinetic effects and Landau damping in fishbone
+modes in both DIII-D and NSTX. It is found that the thermal ion kinetic effects
+can cause an increase of the frequencies of the non-resonant $n=1$ fishbone
+modes driven by energetic particles for $q_\mathrm{min}>1$, and Landau damping
+can provide additional stabilization effects. A nonlinear simulation for $n=1$
+fishbone mode in NSTX is also performed, and the perturbation on magnetic flux
+surfaces and the transport of energetic particles are calculated.",2206.03648v1
+2022-07-12,Resonant Multilevel Amplitude Damping Channels,"We introduce a new set of quantum channels: resonant multilevel amplitude
+damping (ReMAD) channels. Among other instances, they can describe energy
+dissipation effects in multilevel atomic systems induced by the interaction
+with a zero-temperature bosonic environment. At variance with the already known
+class of multilevel amplitude damping (MAD) channels, this new class of maps
+allows the presence of an environment unable to discriminate transitions with
+identical energy gaps. After characterizing the algebra of their composition
+rules, by analyzing the qutrit case, we show that this new set of channels can
+exhibit degradability and antidegradability in vast regions of the allowed
+parameter space. There we compute their quantum capacity and private classical
+capacity. We show that these capacities can be computed exactly also in regions
+of the parameter space where the channels aren't degradable nor antidegradable.",2207.05646v2
+2022-07-14,Estimates for the nonlinear viscoelastic damped wave equation on compact Lie groups,"Let $G$ be a compact Lie group. In this article, we investigate the Cauchy
+problem for a nonlinear wave equation with the viscoelastic damping on $G$.
+More preciously, we investigate some $L^2$-estimates for the solution to the
+homogeneous nonlinear viscoelastic damped wave equation on $G$ utilizing the
+group Fourier transform on $G$. We also prove that there is no improvement of
+any decay rate for the norm $\|u(t,\cdot)\|_{L^2(G)}$ by further assuming the
+$L^1(G)$-regularity of initial data. Finally, using the noncommutative Fourier
+analysis on compact Lie groups, we prove a local in time existence result in
+the energy space $\mathcal{C}^1([0,T],H^1_{\mathcal L}(G)).$",2207.06645v3
+2022-08-04,Normal and Quasinormal Modes of Holographic Multiquark Star,"The quadrupole normal-mode oscillation frequency $f_{n}$ of multiquark star
+are computed for $n=1-5$. At the transition from low to high density multiquark
+in the core region, the first 2 modes jump to larger values, a distinctive
+signature of the presence of the high-density core. When the star oscillation
+couples with spacetime, gravitational waves~(GW) will be generated and the star
+will undergo damped oscillation. The quasinormal modes~(QNMs) of the
+oscillation are computed using two methods, direct scan and WKB, for QNMs with
+small and large imaginary parts respectively. The small imaginary QNMs have
+frequencies $1.5-2.6$ kHz and damping times $0.19-1.7$ secs for multiquark star
+with mass $M=0.6-2.1 M_{\odot}$~(solar mass). The WKB QNMs with large imaginary
+parts have frequencies $5.98-9.81$ kHz and damping times $0.13-0.46$ ms for
+$M\simeq 0.3-2.1 M_{\odot}$. They are found to be the fluid $f-$modes and
+spacetime curvature $w-$modes respectively.",2208.02761v2
+2022-08-10,Erasure qubits: Overcoming the $T_1$ limit in superconducting circuits,"The amplitude damping time, $T_1$, has long stood as the major factor
+limiting quantum fidelity in superconducting circuits, prompting concerted
+efforts in the material science and design of qubits aimed at increasing $T_1$.
+In contrast, the dephasing time, $T_{\phi}$, can usually be extended above
+$T_1$ (via, e.g., dynamical decoupling), to the point where it does not limit
+fidelity. In this article we propose a scheme for overcoming the conventional
+$T_1$ limit on fidelity by designing qubits in a way that amplitude damping
+errors can be detected and converted into erasure errors. Compared to standard
+qubit implementations our scheme improves the performance of fault-tolerant
+protocols, as numerically demonstrated by the circuit-noise simulations of the
+surface code. We describe two simple qubit implementations with superconducting
+circuits and discuss procedures for detecting amplitude damping errors,
+performing entangling gates, and extending $T_\phi$. Our results suggest that
+engineering efforts should focus on improving $T_\phi$ and the quality of
+quantum coherent control, as they effectively become the limiting factor on the
+performance of fault-tolerant protocols.",2208.05461v1
+2022-08-12,Critical exponent for nonlinear wave equations with damping and potential terms,"The aim of this paper is to determine the critical exponent for the nonlinear
+wave equations with damping and potential terms of the scale invariant order,
+by assuming that these terms satisfy a special relation. We underline that our
+critical exponent is different from the one for related equations such as the
+nonlinear wave equation without lower order terms, only with a damping term,
+and only with a potential term. Moreover, we study the effect of the decaying
+order of initial data at spatial infinity. In fact, we prove that not only the
+lower order terms but also the order of the initial data affects the critical
+exponent, as well as the sharp upper and lower bounds of the maximal existence
+time of the solution.",2208.06106v3
+2022-08-17,Conservation laws and variational structure of damped nonlinear wave equations,"All low-order conservation laws are found for a general class of nonlinear
+wave equations in one dimension with linear damping which is allowed to be
+time-dependent. Such equations arise in numerous physical applications and have
+attracted much attention in analysis. The conservation laws describe
+generalized momentum and boost momentum, conformal momentum, generalized
+energy, dilational energy, and light-cone energies. Both the conformal momentum
+and dilational energy have no counterparts for nonlinear undamped wave
+equations in one dimension. All of the conservation laws are obtainable through
+Noether's theorem, which is applicable because the damping term can be
+transformed into a time-dependent self-interaction term by a change of
+dependent variable. For several of the conservation laws, the corresponding
+variational symmetries have a novel form which is different than any of the
+well known variation symmetries admitted by nonlinear undamped wave equations
+in one dimension.",2208.08026v2
+2022-08-27,Impact of the free-streaming neutrinos to the second order induced gravitational waves,"The damping effect of the free-streaming neutrinos on the second order
+gravitational waves is investigated in detail. We solve the Boltzmann equation
+and give the anisotropic stress induced by neutrinos to second order. The first
+order tensor and its coupling with scalar perturbations induced gravitational
+waves are considered. We give the analytic equations of the damping kernel
+functions and finally obtain the energy density spectrum. The results show that
+the free-streaming neutrinos suppress the density spectrum significantly for
+low frequency gravitational waves and enlarge the logarithmic slope $n$ in the
+infrared region ($k \ll k_*$) of the spectrum. For the spectrum of $k_*\sim
+10^{-7}$Hz, the damping effect in the range of $k<k_*$ is significant. The
+combined effect of the first and second order could reduce the amplitude by
+$30\%$ and make $n$ jump from $1.54$ to $1.63$ at $k\sim 10^{-9}$Hz, which may
+be probed by the pulsar timing arrays (PTA) in the future.",2208.12948v1
+2022-08-28,The small mass limit for long time statistics of a stochastic nonlinear damped wave equation,"We study the long time statistics of a class of semi--linear damped wave
+equations with polynomial nonlinearities and perturbed by additive Gaussian
+noise in dimensions 2 and 3. We find that if sufficiently many directions in
+the phase space are stochastically forced, the system is exponentially
+attractive toward its unique invariant measure with a convergent rate that is
+uniform with respect to the mass. Then, in the small mass limit, we prove the
+convergence of the first marginal of the invariant measures in a suitable
+Wasserstein distance toward the unique invariant measure of a stochastic
+reaction--diffusion equation. This together with uniform geometric ergodcity
+implies the validity of the small mass limit for the solutions on the infinite
+time horizon $[0,\infty)$, thereby extending previously known results
+established for the damped wave equations under Lipschitz nonlinearities.",2208.13287v2
+2022-08-30,Results on high energy galactic cosmic rays from the DAMPE space mission,"DAMPE (Dark Matter Particle Explorer) is a satellite-born experiment launched
+in 2015 in a sun-synchronous orbit at 500 km altitude, and it has been taking
+data in stable conditions ever since. Its main goals include the spectral
+measurements up to very high energies, cosmic electrons/positrons and gamma
+rays up to tens of TeV, and protons and nuclei up to hundreds of TeV. The
+detector's main features include the 32 radiation lengths deep calorimeter and
+large geometric acceptance, making DAMPE one of the most powerful space
+instruments in operation, covering with high statistics and small systematics
+the high energy frontier up to several hundreds TeV. The results of spectral
+measurements of different species are shown and discussed.",2208.14300v2
+2022-09-05,Generation and routing of nanoscale droplet solitons without compensation of magnetic damping,"Magnetic droplet soliton is a localized dynamic spin state which can serve as
+a nanoscale information carrier and nonlinear oscillator. The present opinion
+is that the formation of droplet solitons requires the compensation of magnetic
+damping by a torque created by a spin-polarized electric current or pure spin
+current. Here we demonstrate theoretically that nanoscale droplet solitons can
+be generated and routed in ferromagnetic nanostructures with voltage-controlled
+magnetic anisotropy in the presence of uncompensated magnetic damping.
+Performing micromagnetic simulations for the MgO/Fe/MgO trilayer with almost
+perpendicular-to-plane magnetization, we reveal the formation of the droplet
+soliton under a nanoscale gate electrode subjected to a sub-nanosecond voltage
+pulse. The soliton lives up to 50 ns at room temperature and can propagate over
+micrometer distances in a ferromagnetic waveguide due to nonzero gradient of
+the demagnetizing field. Furthermore, we show that an electrical routing of the
+soliton to different outputs of a spintronic device can be realized with the
+aid of an additional semiconducting nanostripe electrode creating controllable
+gradient of the perpendicular magnetic anisotropy.",2209.01893v1
+2022-09-06,Emergence of damped-localized excitations of the Mott state due to disorder,"A key aspect of ultracold bosonic quantum gases in deep optical lattice
+potential wells is the realization of the strongly interacting Mott insulating
+phase. Many characteristics of this phase are well understood, however little
+is known about the effects of a random external potential on its gapped
+quasiparticle and quasihole low-energy excitations. In the present study we
+investigate the effect of disorder upon the excitations of the Mott insulating
+state at zero temperature described by the Bose-Hubbard model. Using a
+field-theoretical approach we obtain a resummed expression for the disorder
+ensemble average of the spectral function. Its analysis shows that disorder
+leads to an increase of the effective mass of both quasiparticle and quasihole
+excitations. Furthermore, it yields the emergence of damped states, which
+exponentially decay during propagation in space and dominate the whole band
+when disorder becomes comparable to interactions. We argue that such
+damped-localized states correspond to single-particle excitations of the
+Bose-glass phase.",2209.02435v2
+2022-09-21,Asymptotic profile of L^2-norm of solutions for wave equations with critical log-damping,"We consider wave equations with a special type of log-fractional damping. We
+study the Cauchy problem for this model in the whole space, and we obtain an
+asymptotic profile and optimal estimates of solutions as time goes to infinity
+in L^2-sense. A maximal discovery of this note is that under the effective
+damping, in case of n = 1 L^2-norm of the solution blows up in infinite time,
+and in case of n = 2 L^2-norm of the solution never decays and never blows up
+in infinite time. The latter phenomenon seems to be a rare case.",2209.10154v2
+2022-09-25,Origin of Immediate Damping of Coherent Oscillations in Photoinduced Charge Density Wave Transition,"In stark contrast to the conventional charge density wave (CDW) materials,
+the one-dimensional CDW on the In/Si(111) surface exhibits immediate damping of
+the CDW oscillation during the photoinduced phase transition. Here, by
+successfully reproducing the experimentally observed photoinduced CDW
+transition on the In/Si(111) surface by performing real-time time-dependent
+density functional theory (rt-TDDFT) simulations, we demonstrate that
+photoexcitation promotes valence electrons from Si substrate to empty surface
+bands composed primarily of the covalent p-p bonding states of the long In-In
+bonds, generating interatomic forces to shorten the long bonds and in turn
+drives coherently the structural transition. We illustrate that after the
+structural transition, the component of these surface bands occurs a switch
+among different covalent In bonds, causing a rotation of the interatomic forces
+by about {\pi}/6 and thus quickly damping the oscillations in feature CDW
+modes. These findings provide a deeper understanding of photoinduced phase
+transitions.",2209.12135v1
+2022-10-11,QKD in the NISQ era: enhancing secure key rates via quantum error correction,"Error mitigation is one of the key challenges in realising the full potential
+of quantum cryptographic protocols. Consequently, there is a lot of interest in
+adapting techniques from quantum error correction (QEC) to improve the
+robustness of quantum cryptographic protocols. In this work, we benchmark the
+performance of different QKD protocols on noisy quantum devices, with and
+without error correction. We obtain the secure key rates of BB84, B92 and BBM92
+QKD protocols over a quantum channel that is subject to amplitude-damping
+noise. We demonstrate, theoretically and via implementations on the IBM quantum
+processors, that B92 is the optimal protocol under amplitude-damping and
+generalized amplitude-damping noise. We then show that the security of the
+noisy BBM92 protocol crucially depends on the type and the mode of distribution
+of an entangled pair. Finally, we implement an error-corrected BB84 protocol
+using dual-rail encoding on a noisy quantum processor, and show that the
+dual-rail BB84 implementation outperforms the conventional BB84 in the presence
+of noise. Our secure key rate calculation also takes into account the effects
+of CNOT imperfections on the error rates of the protocols.",2210.05297v1
+2022-10-17,"Engineering imaginary stark ladder in a dissipative lattice: passive $\mathcal{PT}$ symmetry, K symmetry and localized damping","We study an imaginary stark ladder model and propose a realization of the
+model in a dissipative chain with linearly increasing site-dependent
+dissipation strength. Due to the existence of a $K$-symmetry and passive
+$\mathcal{PT}$ symmetry, the model exhibits quite different feature from its
+Hermitian counterpart. With the increase of dissipation strength, the system
+first undergoes a passive $\mathcal{PT}$-symmetry breaking transition, with the
+shifted eigenvalues changing from real to complex, and then a $K$-symmetry
+restoring transition, characterized by the emergence of pure imaginary spectrum
+with equal spacing. Accordingly, the eigenstates change from
+$\mathcal{PT}$-unbroken extended states to the $\mathcal{PT}$-broken states,
+and finally to stark localized states. In the framework of the quantum open
+system governed by Lindblad equation with linearly increasing site-dependent
+dissipation, we unveil that the dynamical evolution of single particle
+correlation function is governed by the Hamiltonian of the imaginary stark
+ladder model. By studying the dynamical evolution of the density distribution
+under various initial states, we demonstrate that the damping dynamics displays
+distinct behaviors in different regions. A localized damping is observed in the
+strong dissipation limit.",2210.08725v3
+2022-10-18,A quasi-local inhomogeneous dielectric tensor for arbitrary distribution functions,"Treatments of plasma waves usually assume homogeneity, but the parallel
+gradients ubiquitous in plasmas can modify wave propagation and absorption. We
+derive a quasilocal inhomogeneous correction to the plasma dielectric for
+arbitrary distributions by expanding the phase correlation integral and develop
+a novel integration technique that allows our correction to be applied in many
+situations and has greater accuracy than other inhomogeneous dielectric
+formulas found in the literature. We apply this dielectric tensor to the
+lower-hybrid current drive problem and demonstrate that inhomogeneous wave
+damping does not affect the lower-hybrid wave's linear damping condition, and
+in the non-Maxwellian problem damping and propagation should remain unchanged
+except in the case of waves with very large phase velocities.",2210.10214v1
+2022-11-04,On the collisional damping of plasma velocity space instabilities,"For plasma velocity space instabilities driven by particle distributions
+significantly deviated from a Maxwellian, weak collisions can damp the
+instabilities by an amount that is significantly beyond the collisional rate
+itself. This is attributed to the dual role of collisions that tend to relax
+the plasma distribution toward a Maxwellian and to suppress the linearly
+perturbed distribution function. The former effect can dominate in cases where
+the unstable non-Maxwellian distribution is driven by collisionless transport
+on a time scale much shorter than that of collisions, and the growth rate of
+the ideal instability has a sensitive dependence on the distribution function.
+The whistler instability driven by electrostatically trapped electrons is used
+as an example to elucidate such a strong collisional damping effect of plasma
+velocity space instabilities, which is confirmed by first-principles kinetic
+simulations.",2211.02723v3
+2022-11-12,Exponential Stability and exact controllability of a system of coupled wave equations by second order terms (via Laplacian) with only one non-smooth local damping,"The purpose of this work is to investigate the exponential stability of a
+second order coupled wave equations by laplacian with one locally internal
+viscous damping. Firstly, using a unique continuation theorem combined with a
+Carleman estimate, we prove that our system is strongly stable without any
+geometric condition. Secondly, using a combination of the multiplier techniques
+and the frequency domain approach, we show that our system is exponentially
+stable under \textbf{(PMGC)} condition on the damping region without any
+restriction on wave propagation speed (i.e whether the two wave equations
+propagate at the same speed or not)",2211.06706v2
+2022-11-10,Generalized Bagley-Torvik Equation and Fractional Oscillators,"In this paper the Bagley-Torvik Equation is considered with the order of the
+damping term allowed to range between one and two. The solution is found to be
+representable as a convolution of trigonometric and exponential functions with
+the driving force. The properties of the effective decay rate and the
+oscillation frequency with respect to the order of the fractional damping are
+also studied. It is found that the effective decay rate and oscillation
+frequency have a complex dependency on the order of the derivative of the
+damping term and exhibit properties one might expect of a thermodynamic
+Equation of state: critical point, phase change, and lambda transition.",2211.07575v1
+2022-11-21,Lifespan estimates for the compressible Euler equations with damping via Orlicz spaces techniques,"In this paper we are interested in the upper bound of the lifespan estimate
+for the compressible Euler system with time dependent damping and small initial
+perturbations. We employ some techniques from the blow-up study of nonlinear
+wave equations. The novelty consists in the introduction of tools from the
+Orlicz spaces theory to handle the nonlinear term emerging from the pressure $p
+\equiv p(\rho)$, which admits different asymptotic behavior for large and small
+values of $\rho-1$, being $\rho$ the density. Hence we can establish, in high
+dimensions $n\in\{2,3\}$, unified upper bounds of the lifespan estimate
+depending only on the dimension $n$ and on the damping strength, and
+independent of the adiabatic index $\gamma>1$. We conjecture our results to be
+optimal. The method employed here not only improves the known upper bounds of
+the lifespan for $n\in\{2,3\}$, but has potential application in the study of
+related problems.",2211.11377v1
+2022-11-24,A brief introduction to the mathematics of Landau damping,"In these short, rather informal, expository notes I review the current state
+of the field regarding the mathematics of Landau damping, based on lectures
+given at the CIRM Research School on Kinetic Theory, November 14--18, 2022.
+These notes are mainly on Vlasov-Poisson in $(x,v) \in \mathbb T^d \times
+\mathbb R^d$ however a brief discussion of the important case of $(x,v) \in
+\mathbb R^d \times \mathbb R^d$ is included at the end. The focus will be
+nonlinear and these notes include a proof of Landau damping on $(x,v) \in
+\mathbb T^d \times \mathbb R^d$ in the Vlasov--Poisson equations meant for
+graduate students, post-docs, and others to learn the basic ideas of the
+methods involved. The focus is also on the mathematical side, and so most
+references are from the mathematical literature with only a small number of the
+many important physics references included. A few open problems are included at
+the end.
+  These notes are not currently meant for publication so they may not be
+perfectly proof-read and the reference list might not be complete. If there is
+an error or you have some references which you think should be included, feel
+free to send me an email and I will correct it when I get a chance.",2211.13707v1
+2022-12-04,Vibration suppression of a state-of-the-art wafer gripper,"In this paper the implementation of piezoelectrics to a state-of-the-art
+wafer gripper is investigated. The objective is to propose and validate a
+solution method, which includes a mechanical design and control system, to
+achieve at least 5% damping for two eigenmodes of a wafer gripper. This
+objective serves as a 'proof of concept' to show the possibilities of
+implementing a state-of-the-art damping method to an industrial application,
+which in turn can be used to dampen different thin structures. The coupling
+relation between the piezoelectrics and their host structure were used to
+design the placement of the piezoelectric patches, together with modal analysis
+data of the a state-of-the-art wafer gripper. This data had been measured
+through an experimental setup. Active damping has been succesfully implemented
+onto the wafer gripper where positive position feedback (PPF) is used as a
+control algorithm to dampen two eigenmodes.",2212.01854v1
+2022-12-20,Algebra of L-banded Matrices,"Convergence is a crucial issue in iterative algorithms. Damping is commonly
+employed to ensure the convergence of iterative algorithms. The conventional
+ways of damping are scalar-wise, and either heuristic or empirical. Recently,
+an analytically optimized vector damping was proposed for memory
+message-passing (iterative) algorithms. As a result, it yields a special class
+of covariance matrices called L-banded matrices. In this paper, we show these
+matrices have broad algebraic properties arising from their L-banded structure.
+In particular, compact analytic expressions for the LDL decomposition, the
+Cholesky decomposition, the determinant after a column substitution, minors,
+and cofactors are derived. Furthermore, necessary and sufficient conditions for
+an L-banded matrix to be definite, a recurrence to obtain the characteristic
+polynomial, and some other properties are given. In addition, we give new
+derivations of the determinant and the inverse. (It's crucial to emphasize that
+some works have independently studied matrices with this special structure,
+named as L-matrices. Specifically, L-banded matrices are regarded as L-matrices
+with real and finite entries.)",2212.12431v3
+2023-01-23,Non-Markovianity in the time evolution of open quantum systems assessed by means of quantum state distance,"We provide a quantitative evaluation of non-Markovianity (NM) for an XX chain
+of interacting qubits with one end coupled to a reservoir. The NM of several
+non-Markovian spectral densities is assessed in terms of various quantum state
+distance (QSD) measures. Our approach is based on the construction of the
+density matrix of the open chain, without the necessity of a master equation.
+For the quantification of NM we calculate the dynamics of the QSD measures
+between the Markovian-damped and various types of non-Markovian-damped cases.
+Since in the literature several QSD measures, appear in forms that imply trace
+preserving density matrices, we introduced appropriate modifications so as to
+render them applicable to the case of decaying traces. The results produce
+remarkable consistency between the various QSD measures. They also reveal a
+subtle and potentially useful interplay between qubit-qubit interaction and
+non-Markovian damping. Our calculations have also uncovered a surprisingly
+dramatic slowing-down of dissipation by the squared Lorentzian reservoir.",2301.09323v2
+2023-01-26,Optimisation of Power Grid Stability Under Uncertainty,"The increased integration of intermittent and decentralised forms of power
+production has eroded the stability margins of power grids and made it more
+challenging to ensure reliable and secure power transmission. Reliable grid
+operation requires system-scale stability in response to perturbations in
+supply or load; previous studies have shown that this can be achieved by tuning
+the effective damping parameters of the generators in the grid. In this paper,
+we present and analyse the problem of tuning damping parameters when there is
+some uncertainty in the underlying system. We show that sophisticated methods
+that assume no uncertainty can yield results that are less robust than those
+produced by simpler methods. We define a quantile-based metric of stability
+that ensures that power grids remain stable even as worst-case scenarios are
+approached, and we develop optimisation methods for tuning damping parameters
+to achieve this stability. By comparing optimisation methods that rely on
+different assumptions, we suggest efficient heuristics for finding parameters
+that achieve highly stable and robust grids.",2301.11215v1
+2023-02-11,Uniform stabilization for the semi-linear wave equation with nonlinear Kelvin-Voigt damping,"This paper is concerned with the decay estimate of solutions to the
+semilinear wave equation subject to two localized dampings in a bounded domain.
+The first one is of the nonlinear Kelvin-Voigt type and is distributed around a
+neighborhood of the boundary according to the Geometric Control Condition.
+While the second one is a frictional damping and we consider it hurting the
+geometric condition of control. We show uniform decay rate results of the
+corresponding energy for all initial data taken in bounded sets of finite
+energy phase-space. The proof is based on obtaining an observability inequality
+which combines unique continuation properties and the tools of the Microlocal
+Analysis Theory.",2302.05667v1
+2023-02-20,Exponentially stable breather solutions in nonautonomous dissipative nonlinear Schrödinger lattices,"We consider damped and forced discrete nonlinear Schr\""odinger equations on
+the lattice $\mathbb{Z}$. First we establish the existence of periodic and
+quasiperiodic breather solutions for periodic and quasiperiodic driving,
+respectively. Notably, quasiperiodic breathers cannot exist in the system
+without damping and driving. Afterwards the existence of a global uniform
+attractor for the dissipative dynamics of the system is shown. For strong
+dissipation we prove that the global uniform attractor has finite fractal
+dimension and consists of a single trajectory that is confined to a finite
+dimensional subspace of the infinite dimensional phase space, attracting any
+bounded set in phase space exponentially fast. Conclusively, for strong damping
+and periodic (quasiperiodic) forcing the single periodic (quasiperiodic)
+breather solution possesses a finite number of modes and is exponentially
+stable.",2302.09869v2
+2023-02-11,"Quasinormal modes, Hawking radiation and absorption of the massless scalar field for Bardeen black hole surrounded by perfect fluid dark matter","Bardeen black hole surrounded by perfect fluid dark matter for a massless
+scalar field. Our result shows that the oscillation frequency of quasinormal
+modes is enhanced as magnetic charge $g$ or the dark matter parameter $\alpha$
+increases. For damping rate of quasinormal modes, the influence of them is
+different. Specifically, the increase of dark matter parameter $\alpha$ makes
+the damping rate increasing at first and then decreasing. While the damping
+rate is continuously decreasing with the increase of the magnetic charge $g$.
+Moreover, we find that the increase of the dark matter parameter $\alpha$
+enhances the power emission spectrum whereas magnetic charge $g$ suppresses it.
+This means that the lifespan of black holes increases for smaller value of
+$\alpha$ and larger value of $g$ when other parameters are fixed. Finally, the
+absorption cross section of the considered black hole is calculated with the
+help of the partial wave approach. Our result suggests that the absorption
+cross section decreases with the dark matter $\alpha$ or the magnetic charge
+$g$ increasing.",2302.10758v1
+2023-02-24,A Numerical Approach for Modeling the Shunt Damping of Thin Panels with Arrays of Separately Piezoelectric Patches,"Two-dimensional thin plates are widely used in many aerospace and automotive
+applications. Among many methods for the attenuation of vibration of these
+mechanical structures, piezoelectric shunt damping is a promising way. It
+enables a compact vibration damping method without adding significant mass and
+volumetric occupancy. Analyzing the dynamics of these electromechanical systems
+requires precise modeling tools that properly consider the coupling between the
+piezoelectric elements and the host structure. This paper presents a
+methodology for separately shunted piezoelectric patches for achieving higher
+performance on vibration attenuation. The Rayleigh-Ritz method is used for
+performing the modal analysis and obtaining the frequency response functions of
+the electro-mechanical system. The effectiveness of the method is investigated
+for a broader range of frequencies, and it was shown that separately shunted
+piezoelectric patches are more effective.",2302.12525v1
+2023-02-27,"Enhancing quantum synchronization through homodyne measurement, noise and squeezing","Quantum synchronization has been a central topic in quantum nonlinear
+dynamics. Despite rapid development in this field, very few have studied how to
+efficiently boost synchronization. Homodyne measurement emerges as one of the
+successful candidates for this task, but preferably in the semi-classical
+regime. In our work, we focus on the phase synchronization of a harmonic-driven
+quantum Stuart-Landau oscillator, and show that the enhancement induced by
+homodyne measurement persists into the quantum regime. Interestingly, optimal
+two-photon damping rates exist when the oscillator and driving are at resonance
+and with a small single-photon damping rate. We also report noise-induced
+enhancement in quantum synchronization when the single-photon damping rate is
+sufficiently large. Apart from these results, we discover that adding a
+squeezing Hamiltonian can further boost synchronization, especially in the
+semi-classical regime. Furthermore, the addition of squeezing causes the
+optimal two-photon pumping rates to shift and converge.",2302.13465v2
+2023-03-06,Larmor precession in strongly correlated itinerant electron systems,"Many-electron systems undergo a collective Larmor precession in the presence
+of a magnetic field. In a paramagnetic metal, the resulting spin wave provides
+insight into the correlation effects generated by the electron-electron
+interaction. Here, we use dynamical mean-field theory to investigate the
+collective Larmor precession in the strongly correlated regime, where dynamical
+correlation effects such as quasiparticle lifetimes and non-quasiparticle
+states are essential. We study the spin excitation spectrum, which includes a
+dispersive Larmor mode as well as electron-hole excitations that lead to Stoner
+damping. We also extract the momentum-resolved damping of slow spin waves. The
+accurate theoretical description of these phenomena relies on the Ward
+identity, which guarantees a precise cancellation of self-energy and vertex
+corrections at long wavelengths. Our findings pave the way towards a better
+understanding of spin wave damping in correlated materials.",2303.03468v2
+2023-03-19,Asymptotic-preserving finite element analysis of Westervelt-type wave equations,"Motivated by numerical modeling of ultrasound waves, we investigate robust
+conforming finite element discretizations of quasilinear and possibly nonlocal
+equations of Westervelt type. These wave equations involve either a strong
+dissipation or damping of fractional-derivative type and we unify them into one
+class by introducing a memory kernel that satisfies non-restrictive regularity
+and positivity assumptions. As the involved damping parameter is relatively
+small and can become negligible in certain (inviscid) media, it is important to
+develop methods that remain stable as the said parameter vanishes. To this end,
+the contributions of this work are twofold. First, we determine sufficient
+conditions under which conforming finite element discretizations of (non)local
+Westervelt equations can be made robust with respect to the dissipation
+parameter. Secondly, we establish the rate of convergence of the semi-discrete
+solutions in the singular vanishing dissipation limit. The analysis hinges upon
+devising appropriate energy functionals for the semi-discrete solutions that
+remain uniformly bounded with respect to the damping parameter.",2303.10743v1
+2023-03-31,Measurement of the cosmic p+He energy spectrum from 46 GeV to 316 TeV with the DAMPE space mission,"Recent observations of the light component of the cosmic-ray spectrum have
+revealed unexpected features that motivate further and more precise
+measurements up to the highest energies. The Dark Matter Particle Explorer
+(DAMPE) is a satellite-based cosmic-ray experiment that is operational since
+December 2015, continuously collecting data on high-energy cosmic particles
+with very good statistics, energy resolution, and particle identification
+capabilities. In this work, the latest measurements of the energy spectrum of
+proton+helium in the energy range from 46 GeV to 316 TeV are presented. Among
+the most distinctive features of the spectrum, a spectral hardening at
+$\sim$600 GeV has been observed, along with a softening at $\sim$29 TeV
+measured with a 6.6$\sigma$ significance. Moreover, by measuring the energy
+spectrum up to 316 TeV, a strong link is established between space- and
+ground-based experiments, also suggesting the presence of a second hardening at
+$\sim$150 TeV.",2304.00137v4
+2023-04-18,Edge-selective extremal damping from topological heritage of dissipative Chern insulators,"One of the most important practical hallmarks of topological matter is the
+presence of topologically protected, exponentially localised edge states at
+interfaces of regions characterised by unequal topological invariants. Here, we
+show that even when driven far from their equilibrium ground state, Chern
+insulators can inherit topological edge features from their parent Hamiltonian.
+In particular, we show that the asymptotic long-time approach of the
+non-equilibrium steady state, governed by a Lindblad Master equation, can
+exhibit edge-selective extremal damping. This phenomenon derives from edge
+states of non-Hermitian extensions of the parent Chern insulator Hamiltonian.
+The combination of (non-Hermitian) topology and dissipation hence allows to
+design topologically robust, spatially localised damping patterns.",2304.09040v3
+2023-04-25,Weakly damped bosons and precursor gap in the vicinity of an antiferromagnetic metallic transition,"We study the electronic spectral function of a metal in the vicinity of an
+antiferromagnetic (AFM) quantum critical point, focusing on a situation where
+the bare bandwidth of the spin fluctuations is significantly smaller than the
+Fermi energy. In this limit, we identify a range of energies where the
+fermionic quasiparticles near the ""hot spots'' on the Fermi surface are
+strongly scattered by the quantum critical fluctuations, whereas the damping of
+the AFM fluctuations by the electrons is negligible. Within a one-loop
+approximation, there is a parameter range where the $T=0$ spectral function at
+the hot spots has a ""precursor gap'' feature, with a local maximum at a finite
+frequency. However, the ratio of the bare spin wave velocity to the Fermi
+velocity required to obtain a precursor gap is probably too small to explain
+experiments in the electron-doped cuprate superconductors (He et al., Proc.
+Natl. Acad. Sci 116, 3449 (2019)). At lower frequencies, the Landau damping of
+the AFM fluctuations becomes important, and the electronic spectral function
+has the familiar ${\omega}^{-1/2}$ singularity. Our one-loop perturbative
+results are supported by a numerical Monte Carlo simulation of electrons
+coupled to an undamped, nearly-critical AFM mode.",2304.12697v1
+2023-05-04,Vibrational resonance in a damped and two-frequency driven system of particle on a rotating parabola,"In the present work, we examine the role of nonlinearity in vibrational
+resonance (VR) of a forced and damped form of a velocity-dependent potential
+system. Many studies have focused on studying the vibrational resonance in
+different potentials, like bistable potential, asymmetrically deformed
+potential, and rough potential. In this connection, velocity-dependent
+potential systems are very important from a physical point of view (Ex:
+pion-pion interaction, cyclotrons and other electromagnetic devices influenced
+by the Lorentz force, magnetrons, mass spectrometers). They also appear in
+several mechanical contexts. In this paper, we consider a nonlinear dynamical
+system with velocity-dependent potential along with additional damping and
+driven forces, namely a particle moving on a rotating-parabola system, and
+study the effect of two-frequency forcing with a wide difference in the
+frequencies. We report that the system exhibits vibrational resonance in a
+certain range of nonlinear strength. Using the method of separation of motions
+(MSM), an analytical equation for the slow oscillations of the system is
+obtained in terms of the parameters of the fast signal. The analytical
+computations and the numerical studies concur well.",2305.02674v1
+2023-05-08,Information capacity analysis of fully correlated multi-level amplitude damping channels,"The primary objective of quantum Shannon theory is to evaluate the capacity
+of quantum channels. In spite of the existence of rigorous coding theorems that
+quantify the transmission of information through quantum channels,
+superadditivity effects limit our understanding of the channel capacities. In
+this paper, we mainly focus on a family of channels known as multi-level
+amplitude damping channels. We investigate some of the information capacities
+of the simplest member of multi-level Amplitude Damping Channel, a qutrit
+channel, in the presence of correlations between successive applications of the
+channel. We find the upper bounds of the single-shot classical capacities and
+calculate the quantum capacities associated with a specific class of maps after
+investigating the degradability property of the channels. Additionally, the
+quantum and classical capacities of the channels have been computed in
+entanglement-assisted scenarios.",2305.04481v2
+2023-05-09,Lifespan estimates for semilinear damped wave equation in a two-dimensional exterior domain,"Lifespan estimates for semilinear damped wave equations of the form
+$\partial_t^2u-\Delta u+\partial_tu=|u|^p$ in a two dimensional exterior domain
+endowed with the Dirichlet boundary condition are dealt with. For the critical
+case of the semilinear heat equation $\partial_tv-\Delta v=v^2$ with the
+Dirichlet boundary condition and the initial condition $v(0)=\varepsilon f$,
+the corresponding lifespan can be estimated from below and above by
+$\exp(\exp(C\varepsilon^{-1}))$ with different constants $C$. This paper
+clarifies that the same estimates hold even for the critical semilinear damped
+wave equation in the exterior of the unit ball under the restriction of radial
+symmetry. To achieve this result, a new technique to control $L^1$-type norm
+and a new Gagliardo--Nirenberg type estimate with logarithmic weight are
+introduced.",2305.05124v1
+2023-05-19,Cold damping of levitated optically coupled nanoparticles,"Methods for controlling the motion of single particles, optically levitated
+in vacuum, have developed rapidly in recent years. The technique of cold
+damping makes use of feedback-controlled, electrostatic forces to increase
+dissipation without introducing additional thermal fluctuations. This process
+has been instrumental in the ground-state cooling of individual electrically
+charged nanoparticles. Here we show that the same method can be applied to a
+pair of nanoparticles, coupled by optical binding forces. These optical binding
+forces are about three orders of magnitude stronger than typical Coulombic
+inter-particle force and result in a coupled motion of both nanoparticles
+characterized by a pair of normal modes. We demonstrate cold damping of these
+normal modes, either independently or simultaneously, to sub-Kelvin
+temperatures at pressures of 5x10^{-3} mbar. Experimental observations are
+captured by a theoretical model which we use to survey the parameter space more
+widely and to quantify the limits imposed by measurement noise and time delays.
+Our work paves the way for the study of quantum interactions between meso-scale
+particles and the exploration of multiparticle entanglement in levitated
+optomechanical systems.",2305.11809v1
+2023-05-25,Damping of three-dimensional waves on coating films dragged by moving substrates,"Paints and coatings often feature interfacial defects due to disturbances
+during the deposition process which, if they persist until solidification,
+worsen the product quality. In this article, we investigate the stability of a
+thin liquid film dragged by a vertical substrate moving against gravity, a flow
+configuration found in a variety of coating processes. The receptivity of the
+liquid film to three-dimensional disturbances is discussed with Direct
+Numerical Simulations (DNS), an in-house non-linear Integral Boundary Layer
+(IBL) film model, and Linear Stability Analysis (LSA). The thin film model,
+successfully validated with the DNS computations, implements a pseudo-spectral
+approach for the capillary terms that allows for investigating non-periodic
+surface tension dominated flows. The combination of these numerical tools
+allows for describing the mechanisms of capillary and non-linear damping, and
+identifying the instability threshold of the coating processes. The results
+show that transverse modulations can be beneficial for the damping of
+two-dimensional waves within the range of operational conditions considered in
+this study, typical of air-knife and slot-die coating.",2305.16139v3
+2023-06-12,Realizable Eddy Damped Markovian Anisotropic Closure for Turbulence and Rossby Wave Interactions,"A realizable Eddy Damped Markovian Anisotropic Closure (EDMAC) is presented
+for the interaction of two dimensional turbulence and transient waves such as
+Rossby waves. The structure of the EDMAC ensures that it is as computationally
+efficient as the Eddy Damped Quasi Normal Markovian (EDQNM) closure but unlike
+the EDQNM is guaranteed to be realizable in the presence of transient waves.
+Jack Herring's important contributions to laying the foundations of statistical
+dynamical closure theories of fluid turbulence are briefly reviewed. The topics
+covered include equilibrium statistical mechanics, Eulerian and Lagrangian
+statistical dynamical closure theories, and the statistical dynamics of the
+interaction of turbulence with topography. The impact of Herring's work is
+described and placed in the context of related developments. Some of the
+further works that have built on Herring's foundations are discussed. The
+relationships between theoretical approaches employed in statistical classical
+and quantum field theories, and their overlap, are outlined. The seminal
+advances made by the pioneers in strong interaction fluid turbulence are put
+into perspective by comparing related developments in strong interaction
+quantum filed theory.",2306.06921v1
+2023-06-26,Revisiting the damped quantum harmonic oscillator,"We reanalyse the quantum damped harmonic oscillator, introducing three less
+than common features. These are (i) the use of a continuum model of the
+reservoir rather than an ensemble of discrete oscillators, (ii) an exact
+diagonalisation of the Hamiltonian by adapting a technique pioneered by Fano,
+and (iii) the use of the thermofield technique for describing a finite
+temperature reservoir. We recover in this way a number of well-known and some,
+perhaps, less familiar results. An example of the latter is an ab initio proof
+that the oscillator relaxes to the mean-force Gibbs state. We find that special
+care is necessary when comparing the damped oscillator with its undamped
+counterpart as the former has two distinct natural frequencies, one associated
+with short time evolution and the other with longer times.",2306.15013v1
+2023-06-27,SPDER: Semiperiodic Damping-Enabled Object Representation,"We present a neural network architecture designed to naturally learn a
+positional embedding and overcome the spectral bias towards lower frequencies
+faced by conventional implicit neural representation networks. Our proposed
+architecture, SPDER, is a simple MLP that uses an activation function composed
+of a sinusoidal multiplied by a sublinear function, called the damping
+function. The sinusoidal enables the network to automatically learn the
+positional embedding of an input coordinate while the damping passes on the
+actual coordinate value by preventing it from being projected down to within a
+finite range of values. Our results indicate that SPDERs speed up training by
+10x and converge to losses 1,500-50,000x lower than that of the
+state-of-the-art for image representation. SPDER is also state-of-the-art in
+audio representation. The superior representation capability allows SPDER to
+also excel on multiple downstream tasks such as image super-resolution and
+video frame interpolation. We provide intuition as to why SPDER significantly
+improves fitting compared to that of other INR methods while requiring no
+hyperparameter tuning or preprocessing.",2306.15242v1
+2023-07-03,Fast Convergence of Inertial Multiobjective Gradient-like Systems with Asymptotic Vanishing Damping,"We present a new gradient-like dynamical system related to unconstrained
+convex smooth multiobjective optimization which involves inertial effects and
+asymptotic vanishing damping. To the best of our knowledge, this system is the
+first inertial gradient-like system for multiobjective optimization problems
+including asymptotic vanishing damping, expanding the ideas laid out in [H.
+Attouch and G. Garrigos, Multiobjective optimization: an inertial approach to
+Pareto optima, preprint, arXiv:1506.02823, 201]. We prove existence of
+solutions to this system in finite dimensions and further prove that its
+bounded solutions converge weakly to weakly Pareto optimal points. In addition,
+we obtain a convergence rate of order $O(t^{-2})$ for the function values
+measured with a merit function. This approach presents a good basis for the
+development of fast gradient methods for multiobjective optimization.",2307.00975v3
+2023-07-05,Strong convergence rates for a full discretization of stochastic wave equation with nonlinear damping,"The paper establishes the strong convergence rates of a spatio-temporal full
+discretization of the stochastic wave equation with nonlinear damping in
+dimension one and two. We discretize the SPDE by applying a spectral Galerkin
+method in space and a modified implicit exponential Euler scheme in time. The
+presence of the super-linearly growing damping in the underlying model brings
+challenges into the error analysis. To address these difficulties, we first
+achieve upper mean-square error bounds, and then obtain mean-square convergence
+rates of the considered numerical solution. This is done without requiring the
+moment bounds of the full approximations. The main result shows that, in
+dimension one, the scheme admits a convergence rate of order $\tfrac12$ in
+space and order $1$ in time. In dimension two, the error analysis is more
+subtle and can be done at the expense of an order reduction due to an
+infinitesimal factor. Numerical experiments are performed and confirm our
+theoretical findings.",2307.01975v1
+2023-07-12,Decoherence effects on lepton number violation from heavy neutrino-antineutrino oscillations,"We study decoherence effects and phase corrections in heavy
+neutrino-antineutrino oscillations (NNOs), based on quantum field theory with
+external wave packets. Decoherence damps the oscillation pattern, making it
+harder to resolve experimentally. Additionally, it enhances lepton number
+violation (LNV) for processes in symmetry-protected low-scale seesaw models by
+reducing the destructive interference between mass eigenstates. We discuss a
+novel time-independent shift in the phase and derive formulae for calculating
+decoherence effects and the phase shift in the relevant regimes, which are the
+no dispersion regime and transverse dispersion regime. We find that the phase
+shift can be neglected in the parameter region under consideration since it is
+small apart from parameter regions with large damping. In the oscillation
+formulae, decoherence can be included by an effective damping parameter. We
+discuss this parameter and present averaged results, which apply to simulations
+of NNOs in the dilepton-dijet channel at the HL-LHC. We show that including
+decoherence effects can dramatically change the theoretical prediction for the
+ratio of LNV over LNC events.",2307.06208v1
+2023-07-24,Phonon damping in a 2D superfluid: insufficiency of Fermi's golden rule at low temperature,"It is generally accepted that the phonon gas of a superfluid always enters a
+weak coupling regime at sufficiently low temperatures, whatever the strength of
+the interactions between the underlying particles (constitutive of the
+superfluid). Thus, in this limit, we should always be able to calculate the
+damping rate of thermal phonons by applying Fermi's golden rule to the $H\_3$
+Hamiltonian of cubic phonon-phonon coupling taken from quantum hydrodynamics,
+at least in the case of a convex acoustic branch and in the collisionless
+regime (where the eigenfrequency of the considered phonons remains much greater
+than the gas thermalization rate). Using the many-body Green's function method,
+we predict that, unexpectedly, this is not true in two dimensions, contrary to
+the three-dimensional case. We confirm this prediction with classical
+phonon-field simulations and a non-perturbative theory in $H\_3$, where the
+fourth order is regularized by hand, giving a complex energy to the virtual
+phonons of the four-phonon collisional processes. For a weakly interacting
+fluid and a phonon mode in the long-wavelength limit, we predict a damping rate
+about three times lower than that of the golden rule.",2307.12705v1
+2023-08-01,Regularity for the Timoshenko system with fractional damping,"We study, the Regularity of the Timoshenko system with two fractional
+dampings $(-\Delta)^\tau u_t$ and $(-\Delta)^\sigma \psi_t$; both of the
+parameters $(\tau, \sigma)$ vary in the interval $[0,1]$. We note that
+($\tau=0$ or $\sigma=0$) and ($\tau=1$ or $\sigma=1$) the dampings are called
+frictional and viscous, respectively. Our main contribution is to show that the
+corresponding semigroup $S(t)=e^{\mathcal{B}t}$, is analytic for
+$(\tau,\sigma)\in R_A:=[1/2,1]\times[ 1/2,1]$ and determine the Gevrey's class
+$\nu>\dfrac{1}{\phi}$, where $\phi=\left\{\begin{array}{ccc}
+\dfrac{2\sigma}{\sigma+1} &{\rm for} & \sigma\leq \tau,\\\\
+\dfrac{2\tau}{\tau+1} &{\rm for} & \tau\leq \sigma. \end{array}\right.$ \quad
+and \quad $(\tau,\sigma)\in R_{CG}:= (0,1)^2$.",2308.00573v2
+2023-08-16,Large time asymptotics for partially dissipative hyperbolic systems without Fourier analysis: application to the nonlinearly damped p-system,"A new framework to obtain time-decay estimates for partially dissipative
+hyperbolic systems set on the real line is developed. Under the classical
+Shizuta-Kawashima (SK) stability condition, equivalent to the Kalman rank
+condition in control theory, the solutions of these systems decay exponentially
+in time for high frequencies and polynomially for low ones. This allows to
+derive a sharp description of the space-time decay of solutions for large time.
+However, such analysis relies heavily on the use of the Fourier transform that
+we avoid here, developing the ""physical space version"" of the hyperbolic
+hypocoercivity approach introduced by Beauchard and Zuazua, to prove new
+asymptotic results in the linear and nonlinear settings. The new physical space
+version of the hyperbolic hypocoercivity approach allows to recover the natural
+heat-like time-decay of solutions under sharp rank conditions, without
+employing Fourier analysis or $L^1$ assumptions on the initial data. Taking
+advantage of this Fourier-free framework, we establish new enhanced time-decay
+estimates for initial data belonging to weighted Sobolev spaces. These results
+are then applied to the nonlinear compressible Euler equations with linear
+damping. We also prove the logarithmic stability of the nonlinearly damped
+$p$-system.",2308.08280v1
+2023-09-06,Effective Description of the Quantum Damped Harmonic Oscillator: Revisiting the Bateman Dual System,"In this work, we present a quantization scheme for the damped harmonic
+oscillator (QDHO) using a framework known as momentous quantum mechanics. Our
+method relies on a semiclassical dynamical system derived from an extended
+classical Hamiltonian, where the phase-space variables are given by expectation
+values of observables and quantum dispersions. The significance of our study
+lies in its potential to serve as a foundational basis for the effective
+description of open quantum systems (OQS), and the description of dissipation
+in quantum mechanics. By employing the Bateman's dual model as the initial
+classical framework, and undergoing quantization, we demonstrate that our
+description aligns exceptionally well with the well-established Lindblad master
+equation. Furthermore, our approach exhibits robustness and broad applicability
+in the context of OQS, rendering it a versatile and powerful tool for studying
+various phenomena. We intend to contribute to the advancement of quantum
+physics by providing an effective means of quantizing the damped harmonic
+oscillator and shedding light on the behavior of open quantum systems.",2309.02689v1
+2023-09-09,Secondary cosmic-ray nuclei in the model of Galactic halo with nonlinear Landau damping,"We employ our recent model of the cosmic-ray (CR) halo by Chernyshov et al.
+(2022) to compute the Galactic spectra of stable and unstable secondary nuclei.
+In this model, confinement of the Galactic CRs is entirely determined by the
+self-generated Alfvenic turbulence whose spectrum is controlled by nonlinear
+Landau damping. We analyze the physical parameters affecting propagation
+characteristics of CRs, and estimate the best set of free parameters providing
+accurate description of available observational data. We also show that
+agreement with observations at lower energies may be further improved by taking
+into account the effect of ion-neutral damping which operates near the Galactic
+disk.",2309.04772v1
+2023-09-20,On the damping of tidally driven oscillations,"Expansions in the oscillation modes of tidally perturbed bodies provide a
+useful framework for representing tidally induced flows. However, recent work
+has demonstrated that such expansions produce inaccurate predictions for
+secular orbital evolution when mode damping rates are computed independently.
+We explore the coupling of collectively driven modes by frictional and viscous
+dissipation, in tidally perturbed bodies that are both non-rotating and rigidly
+rotating. This exploration leads us to propose an alternative approach to
+treating the damping of tidally driven oscillations that accounts for
+dissipative mode coupling, but which does not require any information beyond
+the eigenfunctions and eigenfrequencies of adiabatic modes.",2309.11502v1
+2023-09-25,Linearly implicit exponential integrators for damped Hamiltonian PDEs,"Structure-preserving linearly implicit exponential integrators are
+constructed for Hamiltonian partial differential equations with linear constant
+damping. Linearly implicit integrators are derived by polarizing the polynomial
+terms of the Hamiltonian function and portioning out the nonlinearly of
+consecutive time steps. They require only a solution of one linear system at
+each time step. Therefore they are computationally more advantageous than
+implicit integrators. We also construct an exponential version of the
+well-known one-step Kahan's method by polarizing the quadratic vector field.
+These integrators are applied to one-dimensional damped Burger's,
+Korteweg-de-Vries, and nonlinear Schr{\""o}dinger equations. Preservation of the
+dissipation rate of linear and quadratic conformal invariants and the
+Hamiltonian is illustrated by numerical experiments.",2309.14184v2
+2023-10-12,Plasmon dispersion and Landau damping in the nonlinear quantum regime,"We study the dispersion properties of electron plasma waves, or plasmons,
+which can be excited in quantum plasmas in the nonlinear regime. In order to
+describe nonlinear electron response to finite amplitude plasmons, we apply the
+Volkov approach to non-relativistic electrons. For that purpose, we use the
+Schr\""odinger equation and describe the electron population of a quantum plasma
+as a mixture of quantum states. Within the kinetic framework that we are able
+to derive from the Volkov solutions, we discuss the role of the wave amplitude
+on the nonlinear plasma response. Finally, we focus on the quantum properties
+of nonlinear Landau damping and study the contributions of multi-plasmon
+absorption and emission processes.",2310.08544v1
+2023-11-09,Landau Damping in an Electron Gas,"Material science methods aim at developing efficient computational schemes
+for describing complex many-body effects and how they are revealed in
+experimentally measurable properties. Bethe-Salpeter equation in the
+self-consistent Hartree-Fock basis is often used for this purpose, and in this
+paper we employ the real-frequency diagrammatic Monte Carlo framework for
+solving the ladder-type Bethe-Salpeter equation for the 3-point vertex function
+(and, ultimately, for the system's polarization) to study the effect of
+electron-hole Coulomb scattering on Landau damping in the homogeneous electron
+gas. We establish how this damping mechanism depends on the Coulomb parameter
+$r_s$ and changes with temperature between the correlated liquid and thermal
+gas regimes. In a broader context of dielectric response in metals, we also
+present the full polarization and the typical dependence of the
+exchange-correlation kernel on frequency at finite momentum and temperature
+within the same computational framework.",2311.05611v2
+2023-11-11,On asymptotic properties of solutions to $σ$-evolution equations with general double damping,"In this paper, we would like to consider the Cauchy problem for semi-linear
+$\sigma$-evolution equations with double structural damping for any $\sigma\ge
+1$. The main purpose of the present work is to not only study the asymptotic
+profiles of solutions to the corresponding linear equations but also describe
+large-time behaviors of globally obtained solutions to the semi-linear
+equations. We want to emphasize that the new contribution is to find out the
+sharp interplay of ``parabolic like models"" corresponding to $\sigma_1 \in
+[0,\sigma/2)$ and ``$\sigma$-evolution like models"" corresponding to $\sigma_2
+\in (\sigma/2,\sigma]$, which together appear in an equation. In this
+connection, we understand clearly how each damping term influences the
+asymptotic properties of solutions.",2311.06660v1
+2023-11-14,Enhanced classical radiation damping of electronic cyclotron motion in the vicinity of the Van Hove singularity in a waveguide,"We study the damping process of electron cyclotron motion and the resulting
+emission in a waveguide using the classical Friedrichs model without relying on
+perturbation analysis such as Fermi's golden rule. A classical Van Hove
+singularity appears at the lower bound (or cut-off frequency) of the dispersion
+associated with each of the electromagnetic field modes in the waveguide. In
+the vicinity of the Van Hove singularity, we found that not only is the decay
+process associated with the resonance pole enhanced (amplification factor ~
+$10^4$) but the branch-point effect is also comparably enhanced. As a result,
+the timescale on which most of the decay occurs is dramatically shortened.
+Further, this suggests that the non-Markovian branch point effect should be
+experimentally observable in the vicinity of the Van Hove singularity. Our
+treatment yields a physically-acceptable solution without the problematic
+runaway solution that is well known to appear in the traditional treatment of
+classical radiation damping based on the Abraham-Lorentz equation.",2311.08121v3
+2023-11-18,The temperature dependent Boltzmann equation beyond local equilibrium assumption,"In this manuscript, we present a temperature dependent Boltzmann equation for
+the particles transport through a environmental reservoir, where the
+temperature refers to the equilibrium temperature of reservoir, a new damping
+force and a inverse damping relaxation time are derived based on the classical
+Boltzmann equation, which have obvious influence on the external force and the
+relaxation time of transport particles. For comparison, we also define a
+non-equilibrium temperature for the transport particle by its distribution
+function out of equilibrium, which is different from the equilibrium
+temperature of reservoir. There exist heat transfer between the transport
+particle and the reservoir, because the whole transport particles are in
+non-equilibrium state. Finally, we illustrate them by an example of
+one-dimensional transport procedure, the damping force and the non-equilibrium
+temperature defined by us are shown numerically.",2311.11028v1
+2023-12-13,"Integrating Superregenerative Principles in a Compact, Power-Efficient NMR/NQR Spectrometer: A Novel Approach with Pulsed Excitation","We present a new approach to Nuclear Quadrupole Resonance (NQR)/Nuclear
+Magnetic Resonance (NMR) spectroscopy, the Damp-Enhanced Superregenerative
+Nuclear Spin Analyser (DESSA). This system integrates Superregenerative
+principles with pulsed sample excitation and detection, offering significant
+advancements over traditional Super-Regenerative Receivers (SRRs). Our approach
+overcomes certain limitations associated with traditional Super-Regenerative
+Receivers (SRRs) by integrating direct digital processing of the oscillator
+response delay time (T$_d$) and an electronic damp unit to regulate the
+excitation pulse decay time (T$_e$). The essence is combining pulsed excitation
+with a reception inspired by, but distinct from, conventional SRRs. The damp
+unit allows a rapid termination of the oscillation pulse and the initiation of
+detection within microseconds, and direct digital processing avoids the need
+for a second lower frequency which is used for quenching in a traditional SRRs,
+thereby avoiding the formation of sidebands. We demonstrate the effectiveness
+of DESSA on a \ch{NaClO3} sample containing the isotope Chlorine-35 where it
+accurately detects the NQR signal with sub-kHz resolution.",2312.08491v1
+2023-12-26,"Dynamical polarization function, plasmons, their damping and collective effects in semi-Dirac bands","We have calculated the dynamical polarization, plasmons and damping rates in
+semi-Dirac bands (SDB's) with zero band gap and half-linear, half-parabolic
+low-energy spectrum. The obtained plasmon dispersions are strongly anisotropic
+and demonstrate some crucial features of both two-dimensional electron gas and
+graphene. Such gapless energy dispersions lead to a localized area of undamped
+and low-damped plasmons in a limited range of the frequencies and wave vectors.
+The calculated plasmon branches demonstrate an increase of their energies for a
+finite tilting of the band structure and a fixed Fermi level which could be
+used as a signature of a specific tilted spectrum in a semi-Dirac band.",2312.16117v1
+2024-01-09,Coherent errors in stabilizer codes caused by quasistatic phase damping,"Quantum error correction is a key challenge for the development of practical
+quantum computers, a direction in which significant experimental progress has
+been made in recent years. In solid-state qubits, one of the leading
+information loss mechanisms is dephasing, usually modelled by phase flip
+errors. Here, we introduce quasistatic phase damping, a more subtle error model
+which describes the effect of Larmor frequency fluctuations due to 1/f noise.
+We show how this model is different from a simple phase flip error model, in
+terms of multi-cycle error correction. Considering the surface code, we provide
+numerical evidence for an error threshold, in the presence of quasistatic phase
+damping and readout errors. We discuss the implications of our results for spin
+qubits and superconducting qubits.",2401.04530v2
+2024-01-19,Composite learning backstepping control with guaranteed exponential stability and robustness,"Adaptive backstepping control provides a feasible solution to achieve
+asymptotic tracking for mismatched uncertain nonlinear systems. However,
+input-to-state stability depends on high-gain feedback generated by nonlinear
+damping terms, and closed-loop exponential stability with parameter convergence
+involves a stringent condition named persistent excitation (PE). This paper
+proposes a composite learning backstepping control (CLBC) strategy based on
+modular backstepping and high-order tuners to compensate for the transient
+process of parameter estimation and achieve closed-loop exponential stability
+without the nonlinear damping terms and the PE condition. A novel composite
+learning mechanism that maximizes the staged exciting strength is designed for
+parameter estimation, such that parameter convergence can be achieved under a
+condition of interval excitation (IE) or even partial IE that is strictly
+weaker than PE. An extra prediction error is employed in the adaptive law to
+ensure the transient performance without nonlinear damping terms. The
+exponential stability of the closed-loop system is proved rigorously under the
+partial IE or IE condition. Simulations have demonstrated the effectiveness and
+superiority of the proposed method in both parameter estimation and control
+compared to state-of-the-art methods.",2401.10785v1
+2024-01-23,Model-Free $δ$-Policy Iteration Based on Damped Newton Method for Nonlinear Continuous-Time H$\infty$ Tracking Control,"This paper presents a {\delta}-PI algorithm which is based on damped Newton
+method for the H{\infty} tracking control problem of unknown continuous-time
+nonlinear system. A discounted performance function and an augmented system are
+used to get the tracking Hamilton-Jacobi-Isaac (HJI) equation. Tracking HJI
+equation is a nonlinear partial differential equation, traditional
+reinforcement learning methods for solving the tracking HJI equation are mostly
+based on the Newton method, which usually only satisfies local convergence and
+needs a good initial guess. Based upon the damped Newton iteration operator
+equation, a generalized tracking Bellman equation is derived firstly. The
+{\delta}-PI algorithm can seek the optimal solution of the tracking HJI
+equation by iteratively solving the generalized tracking Bellman equation.
+On-policy learning and off-policy learning {\delta}-PI reinforcement learning
+methods are provided, respectively. Off-policy version {\delta}-PI algorithm is
+a model-free algorithm which can be performed without making use of a priori
+knowledge of the system dynamics. NN-based implementation scheme for the
+off-policy {\delta}-PI algorithms is shown. The suitability of the model-free
+{\delta}-PI algorithm is illustrated with a nonlinear system simulation.",2401.12882v1
+2024-01-30,The nonlinear dynamic behavior of a Rubber-Layer Roller Bearing (RLRB) for vibration isolation,"In this paper, we study the dynamic behavior of a Rubber-Layer Roller Bearing
+(RLRB) interposed between a spring-mass elemental superstructure and a
+vibrating base. Thanks to the viscoelastic rolling contact between the rigid
+rollers and the rubber layers, the RLRB is able to provide a nonlinear damping
+behavior. The effect of the RLRB geometric and material parameters is
+investigated under periodic base excitation, showing that both periodic and
+aperiodic responses can be achieved. Specifically, since the viscoelastic
+damping is non-monotonic (bell shaped), there exist systemdynamic conditions
+involving the decreasing portion of the damping curve in which a strongly
+nonlinear behavior is experienced. In the second part of the paper, we
+investigate the effectiveness of the nonlinear device in terms of seismic
+isolation. Focusing on the mean shock of the Central Italy 2016 earthquake, we
+opportunely tune the material and geometrical RLRB parameters, showing that a
+significant reduction of both the peak and root-mean-square value of the
+inertial force acting on the superstructure is achieved, compared to the best
+performance of a linear base isolation system.",2401.16880v1
+2024-01-30,Poynting-Robertson damping of laser beam driven lightsails,"Lightsails using Earth-based lasers for propulsion require passive
+stabilization to stay within the beam. This can be achieved through the sail's
+scattering properties, creating optical restoring forces and torques. Undamped
+restoring forces produce uncontrolled oscillations, which could jeopardize the
+mission, but it is not obvious how to achieve damping in the vacuum of space.
+Using a simple two-dimensional model we show that the Doppler effect and
+relativistic aberration of the propelling laser beam create damping terms in
+the optical forces and torques. The effect is similar to the Poynting-Robertson
+effect causing loss of orbital momentum of dust particles around stars, but can
+be enhanced by design of the sail's geometry.",2401.16924v1
+2024-02-29,The Equation of Motion for Taut-Line Buzzers,"Equations of motion are developed for the oscillatory rotation of a disk
+suspended between twisted strings kept under tension by a hanging mass, to
+which additional forces may be applied. In the absence of forcing, damped
+harmonic oscillations are observed to decay with an exponential time envelope
+for two different string types. This is consistent with damping caused by
+string viscosity, rather than air turbulence, and may be quantified in terms of
+a quality factor. To test the proposed equation of motion and model for viscous
+damping within the string, we measure both the natural oscillation frequency
+and the quality factor for widely varied values of string length, string
+radius, disk moment of inertia, and hanging mass. The data are found to scale
+in good accord with predictions. A variation where rotational kinetic energy is
+converted back and forth to spring potential energy is also discussed.",2402.19285v1
+2024-03-08,A design methodology for nonlinear oscillator chains enabling energy localization tuning and soliton stability enhancement with optimal damping,"In this paper, the vibration energy localization in coupled nonlinear
+oscillators is investigated, based on the creation of standing solitons. The
+main objective is to establish a design methodology for mechanical lattices
+using the Nonlinear Schr\""odinger Equation (NLSE) as a guide strategy, even in
+the presence of damping. A three-dimensional diagram is used to illustrate
+stable parameter regions for damped stationary solitons. Moreover, an analysis
+of the influence of the number of oscillators in the system, and a numerical
+investigation regarding the stability of solitonic behavior is done. Through
+numerical analyses, it is observed that the developed algorithm not only has
+the capability to locate the highest amplitudes in the chain of oscillators,
+but also to control the intensity at which these amplitudes are located
+according to design requirements. The outcomes of the proposed methodology
+elucidate the impact that the coupling stiffness has on the stabilization of
+the NLSE, as well as the influence of the number of oscillators on the
+continuity hypothesis. The developed algorithm holds potential for practical
+applications in mechanical engineering since the NLSE is used as a design line
+rather than as a consequence of the phenomenon description.",2403.05176v1
+2024-03-08,Damping Obliquities of Hot Jupiter Hosts by Resonance Locking,"When orbiting hotter stars, hot Jupiters are often highly inclined relative
+to their host star equator planes. By contrast, hot Jupiters orbiting cooler
+stars are more aligned. Prior attempts to explain this correlation between
+stellar obliquity and effective temperature have proven problematic. We show
+how resonance locking -- the coupling of the planet's orbit to a stellar
+gravity mode (g mode) -- can solve this mystery. Cooler stars with their
+radiative cores are more likely to be found with g-mode frequencies increased
+substantially by core hydrogen burning. Strong frequency evolution in resonance
+lock drives strong tidal evolution; locking to an axisymmetric g mode damps
+semi-major axes, eccentricities, and as we show for the first time,
+obliquities. Around cooler stars, hot Jupiters evolve into spin-orbit alignment
+and avoid engulfment. Hotter stars lack radiative cores, and therefore preserve
+congenital spin-orbit misalignments. We focus on resonance locks with
+axisymmetric modes, supplementing our technical results with simple physical
+interpretations, and show that non-axisymmetric modes also damp obliquity.",2403.05616v1
+2002-03-16,Rolling as a continuing collision,"We show that two basic mechanical processes, the collision of particles and
+rolling motion of a sphere on a plane, are intimately related. According to our
+recent findings, the restitution coefficient for colliding spherical particles
+\epsilon, which characterizes the energy loss upon collision, is directly
+related to the rolling friction coefficient \mu_{roll} for a viscous sphere on
+a hard plane. We quantify both coefficients in terms of material constants
+which allow to determine either of them provided the other is known. This
+relation between the coefficients may give rise to a novel experimental
+technique to determine alternatively the coefficient of restitution or the
+coefficient of rolling friction.",0203343v1
+2003-11-21,Quiver coefficients are Schubert structure constants,"We give an explicit natural identification between the quiver coefficients of
+Buch and Fulton, decomposition coefficients for Schubert polynomials, and the
+Schubert structure constants for flag manifolds. This is also achieved in
+K-theory where we give a direct argument that the decomposition coefficients
+have alternating signs, based on a theorem of Brion, which then implies that
+the quiver coefficients have alternating signs. Our identification shows that
+known combinatorial formulas for the latter two numbers give formulas for the
+quiver coefficients.",0311390v1
+2005-01-28,Wilson function transforms related to Racah coefficients,"The irreducible $*$-representations of the Lie algebra $su(1,1)$ consist of
+discrete series representations, principal unitary series and complementary
+series. We calculate Racah coefficients for tensor product representations that
+consist of at least two discrete series representations. We use the explicit
+expressions for the Clebsch-Gordan coefficients as hypergeometric functions to
+find explicit expressions for the Racah coefficients. The Racah coefficients
+are Wilson polynomials and Wilson functions. This leads to natural
+interpretations of the Wilson function transforms. As an application several
+sum and integral identities are obtained involving Wilson polynomials and
+Wilson functions. We also compute Racah coefficients for $U_q(\su(1,1))$, which
+turn out to be Askey-Wilson functions and Askey-Wilson polynomials.",0501511v1
+2009-09-02,A method for creating materials with a desired refraction coefficient,"It is proposed to create materials with a desired refraction coefficient in a
+bounded domain $D\subset \R^3$ by embedding many small balls with constant
+refraction coefficients into a given material. The number of small balls per
+unit volume around every point $x\in D$, i.e., their density distribution, is
+calculated, as well as the constant refraction coefficients in these balls.
+Embedding into $D$ small balls with these refraction coefficients according to
+the calculated density distribution creates in $D$ a material with a desired
+refraction coefficient.",0909.0510v1
+2010-11-16,On spectral properties of the fourth order differential operator with singular coefficients,"A formal fourth order differential operator with a singular coefficient that
+is a linear combination of the Dirac delta-function and its derivatives is
+considered. The asymptotic behavior of spectra and eigenfunctions of a family
+of differential operators with smooth coefficients approximating the singular
+coefficients is studied. We explore how behavior of eigenvalues and
+eigenfunctions is influenced by singular coefficients. The limit operator is
+constructed and is shown to depend on a type of approximation of singular
+coefficients.",1011.3675v1
+2012-03-12,Operator Coefficient Methods for Linear Equations,"New iterative methods for solving linear equations are presented that are
+easy to use, generalize good existing methods, and appear to be faster. The new
+algorithms mix two kinds of linear recurrence formulas. Older methods have
+either high order recurrence formulas with scalars for coefficients, as in
+truncated orthomin, or have 1st order recurrence formulas with matrix
+polynomials for coefficients, as in restarted gcr/gmres. The new methods
+include both: high order recurrence formulas and matrix polynomials for
+coefficients. These methods provide a trade-off between recurrence order and
+polynomial degree that can be exploited to achieve greater efficiency.
+Convergence results are obtained for both constant coefficient and varying
+coefficient methods.",1203.2390v1
+2012-05-24,Stability of the inverse resonance problem for Jacobi operators,"When the coefficients of a Jacobi operator are finitely supported
+perturbations of the 1 and 0 sequences, respectively, the left reflection
+coefficient is a rational function whose poles inside, respectively outside,
+the unit disk correspond to eigenvalues and resonances. By including the zeros
+of the reflection coefficient, we have a set of data that determines the Jacobi
+coefficients up to a translation as long as there is at most one half-bound
+state. We prove that the coefficients of two Jacobi operators are pointwise
+close assuming that the zeros and poles of their left reflection coefficients
+are $\eps$-close in some disk centered at the origin.",1205.5321v1
+2013-03-20,Beyond two criteria for supersingularity: coefficients of division polynomials,"Let E: y^2 = x^3 + Ax + B be an elliptic curve defined over a finite field of
+characteristic p\geq 3. In this paper we prove that the coefficient at
+x^{p(p-1)/2} in the p-th division polynomial \psi_p(x) of E equals the
+coefficient at x^{p-1} in (x^3 + Ax + B)^{(p-1)/2}. The first coefficient is
+zero if and only if the division polynomial has no roots, which is equivalent
+to E being supersingular. Deuring (1941) proved that this supersingularity is
+also equivalent to the vanishing of the second coefficient. So the zero loci of
+the coefficients (as functions of A and B) are equal; the main result in this
+paper is clearly stronger than this last statement.",1303.5002v1
+2014-10-26,Bounds on Kronecker and $q$-binomial coefficients,"We present a lower bound on the Kronecker coefficients for tensor squares of
+the symmetric group via the characters of~$S_n$, which we apply to obtain
+various explicit estimates. Notably, we extend Sylvester's unimodality of
+$q$-binomial coefficients $\binom{n}{k}_q$ as polynomials in~$q$ to derive
+sharp bounds on the differences of their consecutive coefficients. We then
+derive effective asymptotic lower bounds for a wider class of Kronecker
+coefficients.",1410.7087v3
+2015-11-13,Relating the optical absorption coefficient of nanosheet dispersions to the intrinsic monolayer absorption,"The concentration of nanosheet suspensions is an important technological
+parameter which is commonly measured by optical spectroscopy using the
+absorption coefficient to transform absorbance into concentration. However for
+all 2D materials, the absorption coefficient is poorly known, resulting in
+potentially large errors in measured concentration. Here we derive an
+expression relating the optical absorption coefficient of an isotropic ensemble
+of nanosheets to the intrinsic monolayer absorption. This has allowed us to
+calculate the absorption coefficients for suspensions of graphene, MoS2 and
+other 2D materials and allows estimation of the monolayer absorption for new
+materials from careful measurement of the suspension absorption coefficient.",1511.04410v1
+2016-02-22,Fourier Coefficients for Theta Representations on Covers of General Linear Groups,"We show that the theta representations on certain covers of general linear
+groups support certain types of unique functionals. The proof involves two
+types of Fourier coefficients. The first are semi-Whittaker coefficients, which
+generalize coefficients introduced by Bump and Ginzburg for the double cover.
+The covers for which these coefficients vanish identically (resp. do not vanish
+for some choice of data) are determined in full. The second are the Fourier
+coefficients associated with general unipotent orbits. In particular, we
+determine the unipotent orbit attached, in the sense of Ginzburg, to the theta
+representations.",1602.06614v2
+2016-08-05,Quantile Regression for Partially Linear Varying Coefficient Spatial Autoregressive Models,"This paper considers the quantile regression approach for partially linear
+spatial autoregressive models with possibly varying coefficients. B-spline is
+employed for the approximation of varying coefficients. The instrumental
+variable quantile regression approach is employed for parameter estimation. The
+rank score tests are developed for hypotheses on the coefficients, including
+the hypotheses on the non-varying coefficients and the constancy of the varying
+coefficients. The asymptotic properties of the proposed estimators and test
+statistics are both established. Monte Carlo simulations are conducted to study
+the finite sample performance of the proposed method. Analysis of a real data
+example is presented for illustration.",1608.01739v1
+2017-02-05,Jacobi-Type Continued Fractions and Congruences for Binomial Coefficients Modulo Integers $h \geq 2$,"We prove two new forms of Jacobi-type J-fraction expansions generating the
+binomial coefficients, $\binom{x+n}{n}$ and $\binom{x}{n}$, over all $n \geq
+0$. Within the article we establish new forms of integer congruences for these
+binomial coefficient variations modulo any (prime or composite) $h \geq 2$ and
+compare our results with existing known congruences for the binomial
+coefficients modulo primes $p$ and prime powers $p^k$. We also prove new exact
+formulas for these binomial coefficient cases from the expansions of the
+$h^{th}$ convergent functions to the infinite J-fraction series generating
+these coefficients for all $n$.",1702.01374v1
+2017-03-24,On the coefficients of symmetric power $L$-functions,"We study the signs of the Fourier coefficients of a newform. Let $f$ be a
+normalized newform of weight $k$ for $\Gamma_0(N)$. Let $a_f(n)$ be the $n$th
+Fourier coefficient of $f$. For any fixed positive integer $m$, we study the
+distribution of the signs of $\{a_f(p^m)\}_p$, where $p$ runs over all prime
+numbers. We also find out the abscissas of absolute convergence of two
+Dirichlet series with coefficients involving the Fourier coefficients of cusp
+forms and the coefficients of symmetric power $L$-functions.",1703.08344v3
+2017-08-05,A causation coefficient and taxonomy of correlation/causation relationships,"This paper introduces a causation coefficient which is defined in terms of
+probabilistic causal models. This coefficient is suggested as the natural
+causal analogue of the Pearson correlation coefficient and permits comparing
+causation and correlation to each other in a simple, yet rigorous manner.
+Together, these coefficients provide a natural way to classify the possible
+correlation/causation relationships that can occur in practice and examples of
+each relationship are provided. In addition, the typical relationship between
+correlation and causation is analyzed to provide insight into why correlation
+and causation are often conflated. Finally, example calculations of the
+causation coefficient are shown on a real data set.",1708.05069v1
+2017-09-21,On the Global Continuity of the Roots of Families of Monic Polynomials (in Russian),"We raise a question on the existence of continuous roots of families of monic
+polynomials (by the root of a family of polynomials we mean a function of the
+coefficients of polynomials of a given family that maps each tuple of
+coefficients to a root of the polynomial with these coefficients). We prove
+that the family of monic second-degree polynomials with complex coefficients
+and the families of monic fourth-degree and fifth-degree polynomials with real
+coefficients have no continuous root. We also prove that the family of monic
+second-degree polynomials with real coefficients has continuous roots and we
+describe the set of all such roots.",1710.00640v1
+2018-06-27,Using a kinetic BGK model to determine transport coefficients of gas mixtures,"We consider a non reactive two component gas mixture. In a macroscopic
+description of a gas mixture we expect four physical coefficients
+characterizing the physical behaviour of the gases to appear. These are the
+diffusion coefficient, the viscosity coefficient, the heat conductivity and the
+thermal diffusion parameter in the Navier-Stokes equations. We present a
+Chapman-Enskog expansion of a kinetic model for gas mixtures by Klingenberg,
+Pirner and Puppo, 2017 that has three free parameters in order to capture three
+of these four physical coefficients. In addition, we propose several possible
+extensions to an ellipsoidal statistical model for gas mixtures in order to
+capture the fourth coefficient.",1806.11483v1
+2019-07-01,Efficient computation of collisional $\ell$-mixing rate coefficients in astrophysical plasmas,"We present analytical expressions for direct evaluation of $\ell$-mixing rate
+coefficients in proton-excited hydrogen atom collisions and describe a software
+package for efficient numerical evaluation of the collisional rate
+coefficients. Comparisons between rate coefficients calculated with various
+levels of approximation are discussed, highlighting their range of validity.
+These rate coefficients are benchmarked via radio recombination lines for
+hydrogen, evaluating the corresponding departure coefficients from local
+thermal equilibrium.",1907.00972v1
+2019-12-30,The Concordance coefficient: An alternative to the Kruskal-Wallis test,"Kendall rank correlation coefficient is used to measure the ordinal
+association between two measurements. In this paper, we introduce the
+Concordance coefficient as a generalization of the Kendall rank correlation,
+and illustrate its use to measure the ordinal association between quantity and
+quality measures when two or more samples are considered. In this sense, the
+Concordance coefficient can be seen as a generalization of the Kendall rank
+correlation coefficient and an alternative to the non-parametric mean
+rank-based methods to compare two or more samples. A comparison of the proposed
+Concordance coefficient and the classical Kruskal-Wallis statistic is presented
+through a comparison of exact distributions of both statistics.",1912.12880v2
+2020-10-13,Arithmetic properties of Fourier coefficients of meromorphic modular forms,"We investigate integrality and divisibility properties of Fourier
+coefficients of meromorphic modular forms of weight $2k$ associated to positive
+definite integral binary quadratic forms. For example, we show that if there
+are no non-trivial cusp forms of weight $2k$, then the $n$-th coefficients of
+these meromorphic modular forms are divisible by $n^{k-1}$ for every natural
+number $n$. Moreover, we prove that their coefficients are non-vanishing and
+have either constant or alternating signs. Finally, we obtain a relation
+between the Fourier coefficients of meromorphic modular forms, the coefficients
+of the $j$-function, and the partition function.",2010.06297v1
+2022-02-18,Strichartz estimates for equations with structured Lipschitz coefficients,"Sharp Strichartz estimates are proved for Schr\""odinger and wave equations
+with Lipschitz coefficients satisfying additional structural assumptions. We
+use Phillips functional calculus as a substitute for Fourier inversion, which
+shows how dispersive properties are inherited from the constant coefficient
+case. Global Strichartz estimates follow provided that the derivatives of the
+coefficients are integrable. The estimates extend to structured coefficients of
+bounded variations. As applications we derive Strichartz estimates with
+additional derivative loss for wave equations with H\""older-continuous
+coefficients and solve nonlinear Schr\""odinger equations. Finally, we record
+spectral multiplier estimates, which follow from the Strichartz estimates by
+well-known means.",2202.09260v2
+2023-06-07,Machine-Learning Kronecker Coefficients,"The Kronecker coefficients are the decomposition multiplicities of the tensor
+product of two irreducible representations of the symmetric group. Unlike the
+Littlewood--Richardson coefficients, which are the analogues for the general
+linear group, there is no known combinatorial description of the Kronecker
+coefficients, and it is an NP-hard problem to decide whether a given Kronecker
+coefficient is zero or not. In this paper, we show that standard
+machine-learning algorithms such as Nearest Neighbors, Convolutional Neural
+Networks and Gradient Boosting Decision Trees may be trained to predict whether
+a given Kronecker coefficient is zero or not. Our results show that a trained
+machine can efficiently perform this binary classification with high accuracy
+($\approx 0.98$).",2306.04734v1
+2023-10-13,Attacking The Assortativity Coefficient Under A Rewiring Strategy,"Degree correlation is an important characteristic of networks, which is
+usually quantified by the assortativity coefficient. However, concerns arise
+about changing the assortativity coefficient of a network when networks suffer
+from adversarial attacks. In this paper, we analyze the factors that affect the
+assortativity coefficient and study the optimization problem of maximizing or
+minimizing the assortativity coefficient (r) in rewired networks with $k$ pairs
+of edges. We propose a greedy algorithm and formulate the optimization problem
+using integer programming to obtain the optimal solution for this problem.
+Through experiments, we demonstrate the reasonableness and effectiveness of our
+proposed algorithm. For example, rewired edges 10% in the ER network, the
+assortativity coefficient improved by 60%.",2310.08924v1
+2024-01-04,On Clustering Coefficients in Complex Networks,"The clustering coefficient is a valuable tool for understanding the structure
+of complex networks. It is widely used to analyze social networks, biological
+networks, and other complex systems. While there is generally a single common
+definition for the local clustering coefficient, there are two different ways
+to calculate the global clustering coefficient. The first approach takes the
+average of the local clustering coefficients for each node in the network. The
+second one is based on the ratio of closed triplets to all triplets. It is
+shown that these two definitions of the global clustering coefficients are
+strongly inequivalent and may significantly impact the accuracy of the outcome.",2401.02999v1
+2024-02-17,"Clebsch-Gordan coefficients, hypergeometric functions and the binomial distribution","A particular case of degenerate Clebsch-Gordan coefficient can be expressed
+with three binomial coefficients. Such a formula, which may be obtained using
+the standard ladder operator procedure, can also be derived from the
+Racah-Shimpuku formula or from expressions of Clebsch-Gordan coefficients in
+terms of $_3F_2$ hypergeometric functions. The O'Hara interesting
+interpretation of this Clebsch-Gordan coefficient by binomial random variables
+can also be related to hypergeometric functions ($_2F_1$), in the case where
+one of the parameters tends to infinity. This emphasizes the links between
+Clebsch-Gordan coefficients, hypergeometric functions and, what has been less
+exploited until now, the notion of probability within the framework of the
+quantum theory of angular momentum.",2402.11298v1
+1998-10-25,A New Approximation Of ECM Frequencies,"We investigate wave amplification through the Electron Cyclotron Maser
+mechanism.
+  We derive a semi-analytic approximation formula giving the frequencies at
+which the absorption coefficient is negative. The coefficients still need to be
+computed to obtain the largest, and therefore the dominant, coefficient.",9810404v1
+1997-08-28,Index-free Heat Kernel Coefficients,"Using index-free notation, we present the diagonal values of the first five
+heat kernel coefficients associated with a general Laplace-type operator on a
+compact Riemannian space without boundary. The fifth coefficient appears here
+for the first time. For a flat space with a gauge connection, the sixth
+coefficient is given too. Also provided are the leading terms for any
+coefficient, both in ascending and descending powers of the Yang-Mills and
+Riemann curvatures, to the same order as required for the fourth coefficient.
+These results are obtained by directly solving the relevant recursion
+relations, working in Fock-Schwinger gauge and Riemann normal coordinates. Our
+procedure is thus noncovariant, but we show that for any coefficient the
+`gauged' respectively `curved' version is found from the corresponding
+`non-gauged' respectively `flat' coefficient by making some simple covariant
+substitutions. These substitutions being understood, the coefficients retain
+their `flat' form and size. In this sense the fifth and sixth coefficient have
+only 26 and 75 terms respectively, allowing us to write them down. Using
+index-free notation also clarifies the general structure of the heat kernel
+coefficients. In particular, in flat space we find that from the fifth
+coefficient onward, certain scalars are absent. This may be relevant for the
+anomalies of quantum field theories in ten or more dimensions.",9708152v1
+2001-10-16,On the coefficients of a Fibonacci power series,"We give an explicit description of the coefficients of the formal power
+series (1-x)(1-x^2)(1-x^3)(1-x^5)(1-x^8)(1-x^13)... In particular, we show that
+all the coefficients are equal to -1, 0 or 1.",0110160v1
+2002-04-24,On diffusion approximation with discontinuous coefficients,"Convergence of stochastic processes with jumps to diffusion processes is
+investigated in the case when the limit process has discontinuous coefficients.
+  An example is given in which the diffusion approximation of a queueing model
+yields a diffusion process with discontinuous diffusion and drift coefficients.",0204289v1
+2004-02-09,Backward uniqueness for parabolic operators with non-Lipscitz coefficients,"We investigate the relation between the backward uniqueness and the
+regularity of the coefficients for a parabolic operator. A necessary and
+sufficient condition for uniqueness is given in terms of the modulus of
+continuity of the coefficients.",0402138v1
+2006-12-02,K-Nomial Coefficients,"In this paper one extends the binomial and trinomial coefficients to the
+concept of 'k-nomial' coefficients, and one obtains some properties of these.
+As an application one generalizes Pascal's triangle.",0612062v1
+2007-03-09,Binomial identities related to Calabi-Yau differential equations,"When searching for Calabi.Yau differential equations, often different
+formulas for the coefficients give the same differential equation. The
+coefficients are usually sums (simple, double or triple) of products of
+binomial coefficients. This results in numerous binomial identities.",0703255v1
+2007-10-08,Number of binomial coefficients divided by a fixed power of a prime,"We state a general formula for the number of binomial coefficients $n$ choose
+$k$ that are divided by a fixed power of a prime $p$, i.e., the number of
+binomial coefficients divided by $p^j$ and not divided by $p^{j+1}$.",0710.1468v1
+2008-12-17,A uniqueness result on ordinary differential equations with singular coefficients,"We consider the uniqueness of solutions of ordinary differential equations
+where the coefficients may have singularities. We derive upper bounds on the
+the order of singularities of the coefficients and provide examples to
+illustrate the results.",0812.3427v1
+2008-12-21,Bounds on ternary cyclotomic coefficients,"We present a new bound on $A = \max_n |a_{pqr}(n)|$, where $a_{pqr}(n)$ are
+the coefficients of a ternary cyclotomic polynomial. We also prove that two
+consecutive coefficients of such a polynomial differ by at most one.",0812.4024v1
+2009-01-01,Adjustment coefficient for risk processes in some dependent contexts,"Following an article by Muller and Pflug, we study the adjustment coefficient
+of ruin theory in a context of temporal dependency. We provide a consistent
+estimator of this coefficient, and perform some simulations.",0901.0182v1
+2010-06-14,Multivariate linear recursions with Markov-dependent coefficients,"We study a linear recursion with random Markov-dependent coefficients. In a
+""regular variation in, regular variation out"" setup we show that its stationary
+solution has a multivariate regularly varying distribution. This extends
+results previously established for i.i.d. coefficients.",1006.2694v1
+2011-01-17,Turán Inequalities for Three Term Recurrences with Monotonic Coefficients,"We establish some new Tur\'an's type inequalities for orthogonal polynomials
+defined by a three-term recurrence with monotonic coefficients. As a corollary
+we deduce asymptotic bounds on the extreme zeros of orthogonal polynomials with
+polynomially growing coefficients of the three-term recurrence.",1101.3204v1
+2011-02-07,Two binomial coefficient conjectures,"Much is known about binomial coefficients where primes are concerned, but
+considerably less is known regarding prime powers and composites. This paper
+provides two conjectures in these directions, one about counting binomial
+coefficients modulo 16 and one about the value of Binomial[n, 2p] modulo n.",1102.1464v1
+2011-08-16,Topological expansion of the coefficients of zonal polynomials in genus one,"We use a combinatorial interpretation of the coefficients of zonal Kerov
+polynomials as a number of unoriented maps to derive an explicit formula for
+the coefficients in genus one.",1108.3173v1
+2012-02-15,New extensions to the sumsets with polynomial restrictions,"By taking the leading and the second leading coefficients of the Morris
+identity, we get new polynomial coefficients. These coefficients lead to new
+results in the sumsets with polynomial restrictions by the polynomial method of
+N. Alon.",1202.3190v1
+2012-05-18,Characterizing Hilbert modular cusp forms by coefficient size,"Associated to an (adelic) Hilbert modular form is a sequence of `Fourier
+coefficients' which uniquely determine the form. In this paper we characterize
+Hilbert modular cusp forms by the size of their Fourier coefficients. This
+answers in the affirmative a question posed by Winfried Kohnen.",1205.4063v1
+2014-07-28,A Note on Extended Binomial Coefficients,"We study the distribution of the extended binomial coefficients by deriving a
+complete asymptotic expansion with uniform error terms. We obtain the expansion
+from a local central limit theorem and we state all coefficients explicitly as
+sums of Hermite polynomials and Bernoulli numbers.",1407.7429v1
+2014-08-05,Coefficient Bounds for Level 2 Cusp Forms and Modular Functions,"We give explicit upper bounds for the coefficients of arbitrary weight $k$,
+level 2 cusp forms, making Deligne's well-known $O(n^{\frac{k-1}{2}+\epsilon})$
+bound precise. We also derive asymptotic formulas and explicit upper bounds for
+the coefficients of certain level 2 modular functions.",1408.1083v1
+2014-10-05,A note on the Vilenkin-Fourier coefficients,"The main aim of this paper is to find the estimation for Vilenkin-Fourier
+coefficients.",1410.7075v1
+2015-03-18,Methods for Accurate Free Flight Measurement of Drag Coefficients,"This paper describes experimental methods for free flight measurement of drag
+coefficients to an accuracy of approximately 1%. There are two main methods of
+determining free flight drag coefficients, or equivalent ballistic
+coefficients: 1) measuring near and far velocities over a known distance and 2)
+measuring a near velocity and time of flight over a known distance. Atmospheric
+conditions must also be known and nearly constant over the flight path. A
+number of tradeoffs are important when designing experiments to accurately
+determine drag coefficients. The flight distance must be large enough so that
+the projectile's loss of velocity is significant compared with its initial
+velocity and much larger than the uncertainty in the near and/or far velocity
+measurements. On the other hand, since drag coefficients and ballistic
+coefficients both depend on velocity, the change in velocity over the flight
+path should be small enough that the average drag coefficient over the path
+(which is what is really determined) is a reasonable approximation to the value
+of drag coefficient at the near and far velocity. This paper considers these
+tradeoffs as well as practical considerations for obtaining accurate near and
+far velocity measurements and the impact of different sources of error
+(velocity, distance, time, atmospheric conditions, etc.) on the resulting
+accuracy of drag coefficients and ballistic coefficients. For a given level of
+accuracy of various quantities, the method of using near and far velocities
+usually produces drag coefficients with about half the uncertainty of the
+method using a near velocity and time of flight.",1503.05504v1
+2016-07-11,On the growth of the Kronecker coefficients,"We study the rate of growth experienced by the Kronecker coefficients as we
+add cells to the rows and columns indexing partitions. We do this by moving to
+the setting of the reduced Kronecker coefficients.",1607.02887v1
+2018-05-15,Strong Uniqueness of Degenerate SDEs with Hölder diffusion coefficients,"In this paper we prove a new strong uniqueness result and a weak existence
+result for possibly {\it degenerate} multidimensional stochastic differential
+equations with Sobolev diffusion coefficients and rough drifts. In particular,
+examples with H\""older diffusion coefficients are provided to show our results.",1805.05526v1
+2018-06-08,Sums of series involving central binomial coefficients & harmonic numbers,"This paper contains a number of series whose coefficients are products of
+central binomial coefficients & harmonic numbers. An elegant sum involving
+$\zeta(2)$ and two other nice sums appear in the last section.",1806.03998v2
+2018-07-13,Extending the D-Wave with support for Higher Precision Coefficients,"D-Wave only guarantees to support coefficients with 4 to 5 bits of resolution
+or precision. This paper describes a method to extend the functionality of the
+D-Wave to solve problems that require the support of higher precision
+coefficients.",1807.05244v1
+2019-05-23,Linear Statistics with Random Coefficients and Characterization of Hyperbolic Secant Distribution,"There is given a characterization of hyperbolic secant distribution by the
+independence of linear forms with random coefficients. We provide a
+characterization by the identic distribution property. Keywords: hyperbolic
+secant distribution; characterization of distributions; linear forms; random
+coefficients.",1905.09910v1
+2019-05-27,Noncommutative LR coefficients and crystal reflection operators,"We relate noncommutative Littlewood-Richardson coefficients of
+Bessenrodt-Luoto-van Willigenburg to classical Littlewood-Richardson
+coefficients via crystal reflection operators. A key role is played by the
+combinatorics of frank words.",1905.10942v1
+2020-01-29,Rough differential equations with path-dependent coefficients,"We establish the existence of solutions to path-dependent rough differential
+equations with non-anticipative coefficients. Regularity assumptions on the
+coefficients are formulated in terms of horizontal and vertical derivatives.",2001.10688v1
+2020-05-04,Boundary value problem for high order equation with discontinuous coefficients,"The article considers the Dirichlet problem for a high-order mixed-type
+equation that splits into factors, each of which is a Lavrentiev-Bitsadze
+equation with its own excellent coefficient. Sufficient conditions are found
+for the coefficients under which the problem has a classical solution.",2005.01283v1
+2021-06-25,On the divisibility of $q$-trinomial coefficients,"We establish a congruence on sums of central $q$-binomial coefficients. From
+this $q$-congruence, we derive the divisibility of the $q$-trinomial
+coefficients introduced by Andrews and Baxter.",2106.13613v2
+2022-02-20,Some new results about $q$-trinomial coefficients,"In this paper, we present several new congruences on the $q$-trinomial
+coefficients introduced by Andrews and Baxter. A new congruence on sums of
+central $q$-binomial coefficients is also established.",2202.09781v2
+2022-04-21,On analytical formulas for the Virial coefficients,"In many fields of statistical physics, for instance in the study of the
+liquid-gas phase transition in finite nuclear matter, the Virial coefficients
+of the Fermi gas play a major role. In this note, we provide relations, sum
+rules, analytical formulas and numerical values for such coefficients.",2204.13600v1
+2023-06-05,On some conjectural series containing binomial coefficients and harmonic numbers,"Binomial coefficients and harmonic numbers are important in many branches of
+number theory. With the help of the operator method and several summation and
+transformation formulas for hypergeometric series, we prove eight conjectural
+series of Z.-W. Sun containing binomial coefficients and harmonic numbers in
+this paper.",2306.02641v1
+2023-07-27,Congruences concerning quadrinomial coefficients,"In this paper, we establish congruences (mod $p^2$) involving the
+quadrinomial coefficients $\dbinom{np-1}{p-1}_{3}$ and
+$\dbinom{np-1}{\frac{p-1}{2}}_{3}$. This is an analogue of congruences
+involving the trinomial coefficients $\dbinom{np-1}{p-1}_{2}$ and
+$\dbinom{np-1}{\frac{p-1}{2}}_{2}$ due to Elkhiri and Mihoubi.",2307.16768v1
+2024-02-27,Partition-Theoretic Results and Recurrence Relations for the Coefficients of Some Mock Theta Functions,"In the paper, we give partition-theoretic results for the coefficients of
+some mock theta functions and prove their congruence properties. Some
+recurrence relations connecting the coefficients of the mock theta functions
+with certain restricted partition functions are also established.",2402.17551v1
+1995-10-04,Microlensing By a Prolate All-Macho Halo,"It is widely believed that dark matter halos are flattened, that is closer to
+oblate than prolate. The evidence cited is based largely on observations of
+galaxies which do not look anything like our own and on numerical simulations
+which use ad hoc initial conditions. Given what we believe to be a ``reasonable
+doubt'' concerning the shape of dark Galactic halo we calculate the optical
+depth and event rate for microlensing of stars in the LMC assuming a wide range
+of models that include both prolate and oblate halos. We find, in agreement
+with previous analysis, that the optical depth for a spherical (E0) halo and
+for an oblate (E6) halo are roughly the same, essentially because two competing
+effects cancel approximately. However the optical depth for an E6 prolate halo
+is reduced by ~35%. This means that an all-Macho prolate halo with reasonable
+parameters for the Galaxy is consistent with the published microlensing event
+rate.",9510023v1
+1997-04-25,Constraints on the density perturbation spectrum from primordial black holes,"We re-examine the constraints on the density perturbation spectrum, including
+its spectral index $n$, from the production of primordial black holes. The
+standard cosmology, where the Universe is radiation dominated from the end of
+inflation up until the recent past, was studied by Carr, Gilbert and Lidsey; we
+correct two errors in their derivation and find a significantly stronger
+constraint than they did, $n \lesssim 1.25$ rather than their 1.5. We then
+consider an alternative cosmology in which a second period of inflation, known
+as thermal inflation and designed to solve additional relic over-density
+problems, occurs at a lower energy scale than the main inflationary period. In
+that case, the constraint weakens to $n \lesssim 1.3$, and thermal inflation
+also leads to a `missing mass' range, $10^{18} g \lesssim M \lesssim 10^{26}
+g$, in which primordial black holes cannot form. Finally, we discuss the effect
+of allowing for the expected non-gaussianity in the density perturbations
+predicted by Bullock and Primack, which can weaken the constraints further by
+up to 0.05.",9704251v1
+1998-02-26,Inversion of polarimetric data from eclipsing binaries,"We describe a method for determining the limb polarization and limb darkening
+of stars in eclipsing binary systems, by inverting photometric and polarimetric
+light curves.
+  Because of the ill-conditioning of the problem, we use the Backus-Gilbert
+method to control the resolution and stability of the recovered solution, and
+to make quantitative estimates of the maximum accuracy possible. Using this
+method we confirm that the limb polarization can indeed be recovered, and
+demonstrate this with simulated data, thus determining the level of
+observational accuracy required to achieve a given accuracy of reconstruction.
+This allows us to set out an optimal observational strategy, and to critcally
+assess the claimed detection of limb polarization in the Algol system.
+  The use of polarization in stars has been proposed as a diagnostic tool in
+microlensing surveys by Simmons et al. (1995), and we discuss the extension of
+this work to the case of microlensing of extended sources.",9802334v1
+1998-09-04,Cluster-Cluster Strong Lensing: Expectations and Detection Methods,"We calculate the all-sky number of galaxy clusters that are expected to be
+gravitationally lensed by foreground massive clusters. We describe the redshift
+and number distributions of clusters using a Press-Schechter analysis, and
+model the foreground lensing clusters as singular isothermal spheres. If
+Omega_m=0.3 and Omega_Lambda=0.7, we expect ~ 30 cluster-cluster strong lensing
+events that involve foreground X-ray luminous clusters with total mass greater
+than 7.5 x 10^14 h^-1 M_sun, or X-ray luminosity L_x (2-10 keV) 8 x 10^44 h^-2
+ergs s^-1, and background clusters with total mass greater than 10^14 h^-1
+M_sun. The number expected in an open universe with Omega_m = 0.3 is less than
+\~ 4. Because of uncertainty in sigma_8, the root-mean-square density
+fluctuations in spheres of radius 8 h^-1 Mpc, the exact number of such lensing
+events is uncertain by a factor of about 5. We examine methods to detect
+cluster-cluster lensing events based on optical, X-ray, and Sunyaev-Zel'dovich
+effect observations.",9809062v3
+2000-04-14,Source Reconstruction as an Inverse Problem,"Inverse Problem techniques offer powerful tools which deal naturally with
+marginal data and asymmetric or strongly smoothing kernels, in cases where
+parameter-fitting methods may be used only with some caution. Although they are
+typically subject to some bias, they can invert data without requiring one to
+assume a particular model for the source. The Backus-Gilbert method in
+particular concentrates on the tradeoff between resolution and stability, and
+allows one to select an optimal compromise between them. We use these tools to
+analyse the problem of reconstructing features of the source star in a
+microlensing event, show that it should be possible to obtain useful
+information about the star with reasonably obtainable data, and note that the
+quality of the reconstruction is more sensitive to the number of data points
+than to the quality of individual ones.",0004200v1
+2000-04-18,"Galaxy Cluster Baryon Fractions, Cluster Surveys and Cosmology","The properties of nearby galaxy clusters limit the range of cosmological
+parameters consistent with our universe. We describe the limits which arise
+from studies of the intracluster medium (ICM) mass fraction fICM and
+consideration of the possible sources of systematic error:
+Omega_M<0.44h_{50}^{-1/2} at 95% confidence. We emphasize that independent of
+Type Ia supernovae (SNe Ia) observations, this cluster study, taken together
+with published cosmic microwave background (CMB) anisotropy studies, indicates
+a non-zero quintessence or dark energy component Omega_Q>0.
+  We then discuss future galaxy cluster surveys which will probe the abundance
+of galaxy clusters to intermediate and high redshift. We investigate the
+sensitivity of these surveys to the cosmological density parameter Omega_M and
+the equation of state parameter w of any quintessence component. In particular,
+we show that cluster survey constraints from a proposed large solid angle X-ray
+survey are comparable in precision and complementary in nature to constraints
+expected from future CMB anisotropy and SNe Ia studies.",0004244v1
+2000-05-11,Measurement of [OIII] Emission in Lyman Break Galaxies,"Measurements of [OIII] emission in Lyman Break galaxies (LBGs) at z>3 are
+presented. Four galaxies were observed with narrow-band filters using the
+Near-IR Camera on the Keck I 10-m telescope. A fifth galaxy was observed
+spectroscopically during the commissioning of NIRSPEC, the new infrared
+spectrometer on Keck II. The emission-line spectrum is used to place limits on
+the metallicity. Comparing these new measurements with others available from
+the literature, we find that strong oxygen emission in LBGs may suggest
+sub-solar metallicity for these objects. The [OIII]5007 line is also used to
+estimate the star formation rate (SFR) of the LBGs. The inferred SFRs are
+higher than those estimated from the UV continuum, and may be evidence for dust
+extinction.",0005254v1
+2001-03-02,Clusters in the Precision Cosmology Era,"Over the coming decade, the observational samples available for studies of
+cluster abundance evolution will increase from tens to hundreds, or possibly to
+thousands, of clusters. Here we assess the power of future surveys to determine
+cosmological parameters. We quantify the statistical differences among
+cosmologies, including the effects of the cosmic equation of state parameter w,
+in mock cluster catalogs simulating a 12 sq. deg Sunyaev-Zeldovich Effect
+survey and a deep 10^4 sq. deg X-ray survey. The constraints from clusters are
+complementary to those from studies of high-redshift Supernovae (SNe), CMB
+anisotropies, or counts of high-redshift galaxies. Our results indicate that a
+statistical uncertainty of a few percent on both Omega_m and w can be reached
+when cluster surveys are used in combination with any of these other datasets.",0103049v1
+2002-07-05,New Tests of the Cluster Entropy Floor Hypothesis,"Recent efforts to account for the observed X-ray luminosity - temperature
+relation of galaxy clusters has led to suggestions that the ICM has an apparent
+``entropy floor'' at or above the level of 300 keV cm^2. Here, we propose new
+tests based on the thermal Sunyaev-Zeldovich effect and on the cluster gas mass
+- temperature trend (from X-ray data) to probe the level of excess entropy in
+the ICM. We show that these new tests lend further support to the case for a
+high entropy floor in massive clusters.",0207147v1
+2003-06-18,Kinematic Masses of Super Star Clusters in M82 from High-Resolution Near-Infrared Spectroscopy,"Using high-resolution (R~22,000) near-infrared (1.51 -- 1.75 microns) spectra
+from Keck Observatory, we measure the kinematic masses of two super star
+clusters in M82. Cross-correlation of the spectra with template spectra of cool
+evolved stars gives stellar velocity dispersions of sigma_r=15.9 +/- 0.8 km/s
+for MGG-9 and sigma_r=11.4 +/- 0.8 km/s for MGG-11. The cluster spectra are
+dominated by the light of red supergiants, and correlate most closely with
+template supergiants of spectral types M0 and M4.5. We fit King models to the
+observed profiles of the clusters in archival HST/NICMOS images to measure the
+half-light radii. Applying the virial theorem, we determine masses of 1.5 +/-
+0.3 x 10^6 M_sun for MGG-9 and 3.5 +/- 0.7 x 10^5 M_sun for MGG-11. Population
+synthesis modelling suggests that MGG-9 is consistent with a standard initial
+mass function, whereas MGG-11 appears to be deficient in low-mass stars
+relative to a standard IMF. There is, however, evidence of mass segregation in
+the clusters, in which case the virial mass estimates would represent lower
+limits.",0306373v1
+2003-09-10,The CMB Quadrupole in a Polarized Light,"The low quadrupole of the cosmic microwave background (CMB), measured by COBE
+and confirmed by WMAP, has generated much discussion recently. We point out
+that the well-known correlation between temperature and polarization
+anisotropies of the CMB further constrains the low multipole anisotropy data.
+This correlation originates from the fact that the low-multipole polarization
+signal is sourced by the CMB quadrupole as seen by free electrons during the
+relatively recent cosmic history. Consequently, the large-angle temperature
+anisotropy data make restrictive predictions for the large-angle polarization
+anisotropy, which depend primarily on the optical depth for electron scattering
+after cosmological recombination, tau. We show that if current cosmological
+models for the generation of large angle anisotropy are correct and the
+COBE/WMAP data are not significantly contaminated by non-CMB signals, then the
+observed C_te amplitude on the largest scales is discrepant at the 99.8% level
+with the observed C_tt for the concordance LCDM model with tau=0.10. Using
+tau=0.17, the preferred WMAP model-independent value, the discrepancy is at the
+level of 98.5%.",0309281v2
+2003-10-11,Statistics of Giant Arcs in Galaxy Clusters,"We study the expected properties and statistics of giant arcs produced by
+galaxy clusters in a LambdaCDM universe and investigate how the characteristics
+of CDM clusters determine the properties of the arcs they generate. Due to the
+triaxiality and substructure of CDM halos, the giant arc cross section for
+individual clusters varies by more than an order of magnitude as a function of
+viewing angle. In addition, the shallow density cusps and triaxiality of CDM
+clusters cause systematic alignments of giant arcs which should be testable
+with larger samples from forthcoming lensing surveys. We compute the predicted
+statistics of giant arcs for the LambdaCDM model and compare to results from
+previous surveys. The predicted arc statistics are in excellent agreement with
+the numbers of giant arcs observed around low redshift (0.2 < z < 0.6) clusters
+from the EMSS sample, however there are hints of a possible excess of arcs
+observed around high redshift z > 0.6 clusters. This excess, if real, appears
+to be due to the presence of highly massive or concentrated clusters at high
+redshifts.",0310306v1
+2004-01-23,Gravitational Lensing of the Microwave Background by Galaxy Clusters,"Galaxy clusters will distort the pattern of temperature anisotropies in the
+microwave background via gravitational lensing. We create lensed microwave
+background maps using clusters drawn from numerical cosmological simulations. A
+distinctive dipole-like temperature fluctuation pattern is formed aligned with
+the underlying microwave temperature gradient. For a massive cluster, the
+characteristic angular size of the temperature distortion is a few arcminutes
+and the characteristic amplitude a few micro-Kelvin. We demonstrate a simple
+technique for estimating the lensing deflection induced by the cluster;
+microwave background lensing measurements have the potential to determine the
+mass distribution for some clusters with good accuracy on angular scales up to
+a few arcminutes. Future high-resolution and high-sensitivity microwave
+background maps will have the capability to detect lensing by clusters; we
+discuss various systematic limitations on probing cluster masses using this
+technique.",0401519v2
+2004-04-15,Is the slope of the intrinsic Baldwin effect constant?,"We investigate the relationship between emission-line strength and continuum
+luminosity in the best-studied nearby Seyfert 1 galaxy NGC5548. Our analysis of
+13 years of ground-based optical monitoring data reveals significant
+year-to-year variations in the observed H-beta emission-line response in this
+source. More specifically, we confirm the result of Gilbert and Peterson (2003)
+of a non-linear relationship between the continuum and H-beta emission-line
+fluxes. Furthermore, we show that the slope of this relation is not constant,
+but rather decreases as the continuum flux increases. Both effects are
+consistent with photoionisation model predictions of a luminosity-dependent
+response in this line.",0404296v1
+2005-08-04,"Gravitino, Axino, Kaluza-Klein Graviton Warm and Mixed Dark Matter and Reionisation","Stable particle dark matter may well originate during the decay of long-lived
+relic particles, as recently extensively examined in the cases of the axino,
+gravitino, and higher-dimensional Kaluza-Klein (KK) graviton. It is shown that
+in much of the viable parameter space such dark matter emerges naturally
+warm/hot or mixed. In particular, decay produced gravitinos (KK-gravitons) may
+only be considered cold for the mass of the decaying particle in the several
+TeV range, unless the decaying particle and the dark matter particle are almost
+degenerate. Such dark matter candidates are thus subject to a host of
+cosmological constraints on warm and mixed dark matter, such as limits from a
+proper reionisation of the Universe, the Lyman-alpha forest, and the abundance
+of clusters of galaxies.. It is shown that constraints from an early
+reionsation epoch, such as indicated by recent observations, may potentially
+limit such warm/hot components to contribute only a very small fraction to the
+dark matter.",0508141v2
+1999-08-10,Magnetic relaxation in a classical spin chain as model for nanowires,"With decreasing particle size, different mechanisms dominate the thermally
+activated magnetization reversal in ferromagnetic particles. We investigate
+some of these mechanisms for the case of elongated, single-domain nanoparticles
+which we describe by a classical Heisenberg spin chain driven by an external
+magnetic field. For sufficiently small system size the magnetic moments rotate
+coherently. With increasing size a crossover to a reversal due to
+soliton-antisoliton nucleation sets in. For even larger systems many of these
+soliton-antisoliton pairs nucleate at the same time. These effects give rise to
+a complex size dependence of the energy barriers and characteristic time scales
+of the relaxation. We study these quantities using Monte Carlo simulations as
+well as a direct integration of the Landau-Lifshitz-Gilbert equation of motion
+with Langevin dynamics and we compare our results with asymptotic solutions for
+the escape rate following from the Fokker-Planck equation. Also, we investigate
+the crossover from coherent rotation to soliton-antisoliton nucleation and
+multi-droplet nucleation, especially its dependence on the system size, the
+external field and the anisotropy of the system.",9908150v1
+2000-07-17,Fine-grid Simulations of Thermally Activated Switching in Nanoscale Magets,"Numerical integration of the Landau-Lifshitz-Gilbert equation with thermal
+fluctuations is used to study the dynamic response of single-domain nanomagnets
+to rapid changes in the applied magnetic field. The simulation can resolve
+magnetization patterns within nanomagnets and uses the Fast Multipole method to
+calculate dipole-dipole interactions efficiently. The thermal fluctuations play
+an essential part in the reversal process whenever the applied field is less
+than the zero-temperature coercive field. In this situation pillar-shaped
+nanomagnets are found to reverse through a local curling mode that involves the
+formation and propagation of a domain wall. Tapering the ends of the pillars to
+reduce pole-avoidance effects changes the energies involved but not the
+fundamental process. The statistical distribution of switching times is well
+described by the independent nucleation and subsequent growth of regions of
+reversed magnetization at both ends of the pillar.",0007279v1
+2001-01-31,Langevin Simulation of Thermally Activated Magnetization Reversal in Nanoscale Pillars,"Numerical solutions of the Landau-Lifshitz-Gilbert micromagnetic model
+incorporating thermal fluctuations and dipole-dipole interactions (calculated
+by the Fast Multipole Method) are presented for systems composed of nanoscale
+iron pillars of dimension 9 nm x 9 nm x 150 nm. Hysteresis loops generated
+under sinusoidally varying fields are obtained, while the coercive field is
+estimated to be 1979 $\pm$ 14 Oe using linear field sweeps at T=0 K. Thermal
+effects are essential to the relaxation of magnetization trapped in a
+metastable orientation, such as happens after a rapid reversal of an external
+magnetic field less than the coercive value. The distribution of switching
+times is compared to a simple analytic theory that describes reversal with
+nucleation at the ends of the nanomagnets. Results are also presented for
+arrays of nanomagnets oriented perpendicular to a flat substrate. Even at a
+separation of 300 nm, where the field from neighboring pillars is only $\sim$ 1
+Oe, the interactions have a significant effect on the switching of the magnets.",0101477v2
+2001-05-04,On a common circle: natural scenes and Gestalt rules,"To understand how the human visual system analyzes images, it is essential to
+know the structure of the visual environment. In particular, natural images
+display consistent statistical properties that distinguish them from random
+luminance distributions. We have studied the geometric regularities of oriented
+elements (edges or line segments) present in an ensemble of visual scenes,
+asking how much information the presence of a segment in a particular location
+of the visual scene carries about the presence of a second segment at different
+relative positions and orientations. We observed strong long-range correlations
+in the distribution of oriented segments that extend over the whole visual
+field. We further show that a very simple geometric rule, cocircularity,
+predicts the arrangement of segments in natural scenes, and that different
+geometrical arrangements show relevant differences in their scaling properties.
+Our results show similarities to geometric features of previous physiological
+and psychophysical studies. We discuss the implications of these findings for
+theories of early vision.",0105097v1
+2002-10-11,Fluctuations and Dissipation of Coherent Magnetization,"A quantum mechanical model is used to derive a generalized Landau-Lifshitz
+equation for a magnetic moment, including fluctuations and dissipation. The
+model reproduces the Gilbert-Brown form of the equation in the classical limit.
+The magnetic moment is linearly coupled to a reservoir of bosonic degrees of
+freedom. Use of generalized coherent states makes the semiclassical limit more
+transparent within a path-integral formulation. A general
+fluctuation-dissipation theorem is derived. The magnitude of the magnetic
+moment also fluctuates beyond the Gaussian approximation. We discuss how the
+approximate stochastic description of the thermal field follows from our
+result. As an example, we go beyond the linear-response method and show how the
+thermal fluctuations become anisotropy-dependent even in the uniaxial case.",0210273v2
+2002-11-18,Field dependence of magnetization reversal by spin transfer,"We analyse the effect of the applied field (Happl) on the current-driven
+magnetization reversal in pillar-shaped Co/Cu/Co trilayers, where we observe
+two different types of transition between the parallel (P) and antiparallel
+(AP) magnetic configurations of the Co layers. If Happl is weaker than a rather
+small threshold value, the transitions between P and AP are irreversible and
+relatively sharp. For Happl exceding the threshold value, the same transitions
+are progressive and reversible. We show that the criteria for the stability of
+the P and AP states and the experimentally observed behavior can be precisely
+accounted for by introducing the current-induced torque of the spin transfer
+models in a Landau-Lifschitz-Gilbert equation. This approach also provides a
+good description for the field dependence of the critical currents.",0211371v1
+2003-10-18,NMR Investigation of the Organic Conductor lambda-(BETS)2FeCl4,"The two-dimensional organic conductor lambda-(BETS)2FeCl4 has an unusual
+phase diagram as a function of temperature and magnetic field that includes a
+paramagnetic metal (PM) phase, an antiferromagnetic insulating (AFI) phase, and
+a field-induced superconducting phase [S. Uji, H. Kobayashi, L. Balicas, and
+James S. Brooks, Adv. Mater. 14, 243 (2002), and cited references]. Here, we
+report a preliminary investigation of the PM and AFI phases at 9.0 T over the
+temperature range 2.0-180 K that uses proton NMR measurements of the spectrum,
+the spin-lattice relaxation rate (1/T1), and the spin echo decay rate (1/T2).
+The sample is asmall single crystal whose mass is approximately 3 micrograms
+(approximately 2E16 protons). Its small size creates several challenges that
+include detecting small signals and excluding parasitic proton signals that are
+not from the sample [H. N. Bachman and I. F. Silvera, J. Mag. Res. 162, 417
+(2003)]. These strategies and other techniques used to obtain viable signals
+are described.",0310433v1
+2004-04-22,Non-collinear magnetic structures: a possible cause for current induced switching,"Current induced switching in Co/Cu/Co trilayers is described in terms of
+ab-initio determined magnetic twisting energies and corresponding sheet
+resistances. In viewing the twisting energy as an energy flux the
+characteristic time thereof is evaluated by means of the
+Landau-Lifshitz-Gilbert equation using ab-initio parameters. The obtained
+switching times are in very good agreement with available experimental data. In
+terms of the calculated currents, scalar quantities since a classical Ohm's law
+is applied, critical currents needed to switch magnetic configurations from
+parallel to antiparallel and vice versa can unambiguously be defined. It is
+found that the magnetoresistance viewed as a function of the current is
+essentially determined by the twisting energy as a function of the relative
+angle between the orientations of the magnetization in the magnetic slabs,
+which in turn can also explain in particular cases the fact that after having
+switched off the current the system remains in the switched magnetic
+configuration. For all ab-initio type calculations the fully relativistic
+Screened Korringa-Kohn-Rostoker method and the corresponding Kubo-Greenwood
+equation in the context of density functional theory are applied.",0404534v1
+2004-06-21,Basic considerations for magnetization dynamics in the combined presence of spin-transfer torques and thermal fluctuations,"This article reviews basic theoretical features of Gilbert magnetization
+dynamics of a single domain magnetic film in the presence of Slonczewski
+spin-transfer torques, with and without thermal fluctuations taken into
+account. Rather than showing results of detailed numerical calculations, the
+discussion here is restricted to basic analytical results and conclusions which
+can mostly be derived from simply the form of the equations of motion, as well
+as elementary considerations based on classical stability analysis and the
+fluctuation-dissipation theorem. The presents work describes how interesting
+features of spin-transfer may be viewed as arising from non-equilibrium
+thermodynamics that are a direct consequence of the nonreciprocal nature of
+spin-transfer torques. The present article discusses fairly general results for
+spin-torque induced instability without thermal fluctuations, as well as the
+case of thermally activated magnetization reversal in uniaxial devices in the
+combined presence of external fields, thermal fluctuations, and spin-transfer
+torques. The results will be discussed and briefly compared and contrasted with
+that of prior work.",0406486v1
+2004-06-24,Thermal Effects on the Magnetic Field Dependence of Spin Transfer Induced Magnetization Reversal,"We have developed a self-aligned, high-yield process to fabricate CPP
+(current perpendicular to the plane) magnetic sensors of sub 100 nm dimensions.
+A pinned synthetic antiferromagnet (SAF) is used as the reference layer which
+minimizes dipole coupling to the free layer and field induced rotation of the
+reference layer. We find that the critical currents for spin transfer induced
+magnetization reversal of the free layer vary dramatically with relatively
+small changes the in-plane magnetic field, in contrast to theoretical
+predictions based on stability analysis of the Gilbert equations of
+magnetization dynamics including Slonczewski-type spin-torque terms. The
+discrepancy is believed due to thermal fluctuations over the time scale of the
+measurements. Once thermal fluctuations are taken into account, we find good
+quantitative agreement between our experimental results and numerical
+simulations.",0406574v1
+2004-07-23,Micromagnetic understanding of current-driven domain wall motion in patterned nanowires,"In order to explain recent experiments reporting a motion of magnetic domain
+walls (DW) in nanowires carrying a current, we propose a modification of the
+spin transfer torque term in the Landau-Lifchitz-Gilbert equation. We show that
+it explains, with reasonable parameters, the measured DW velocities as well as
+the variation of DW propagation field under current. We also introduce
+coercivity by considering rough wires. This leads to a finite DW propagation
+field and finite threshold current for DW propagation, hence we conclude that
+threshold currents are extrinsic. Some possible models that support this new
+term are discussed.",0407628v2
+2004-08-07,Hysteresis multicycles in nanomagnet arrays,"We predict two new physical effects in arrays of single-domain nanomagnets by
+performing simulations using a realistic model Hamiltonian and physical
+parameters. First, we find hysteretic multicycles for such nanomagnets. The
+simulation uses continuous spin dynamics through the Landau-Lifshitz-Gilbert
+(LLG) equation. In some regions of parameter space, the probability of finding
+a multicycle is as high as ~0.6. We find that systems with larger and more
+anisotropic nanomagnets tend to display more multicycles. This result
+demonstrates the importance of disorder and frustration for multicycle
+behavior. We also show that there is a fundamental difference between the more
+realistic vector LLG equation and scalar models of hysteresis, such as Ising
+models. In the latter case, spin and external field inversion symmetry is
+obeyed but in the former it is destroyed by the dynamics, with important
+experimental implications.",0408158v1
+2004-12-03,High frequency magnetic permeability of nanocomposite film,"The high frequency magnetic permeability of nanocomposite film consisting of
+the single-domain spherical ferromagnetic particles in the dielectric matrix is
+studied. The permeability is assumed to be determined by rotation of the
+ferromagnetic inclusion magnetic moments around equilibrium direction in AC
+magnetic field. The composite is modeled by a cubic array of ferromagnetic
+particles. The magnetic permeability tensor is calculated by solving the
+Landau-Lifshits-Gilbert equation accounting for the dipole interaction of
+magnetic particles. The permeability tensor components are found as functions
+of the frequency, temperature, ferromagnetic inclusions density and magnetic
+anisotropy. The obtained results show that nanocomposite films could have
+rather high value of magnetic permeability in the microwave range.",0412073v1
+2005-01-07,Dielectric resonances of ordered passive arrays,"The electrical and optical properties of ordered passive arrays, constituted
+of inductive and capacitive components, are usually deduced from Kirchhoff's
+rules. Under the assumption of periodic boundary conditions, comparable results
+may be obtained via an approach employing transfer matrices. In particular,
+resonances in the dielectric spectrum are demonstrated to occur if all
+eigenvalues of the transfer matrix of the entire array are unity. The latter
+condition, which is shown to be equivalent to the habitual definition of a
+resonance in impedance for an array between electrodes, allows for a convenient
+and accurate determination of the resonance frequencies, and may thus be used
+as a tool for the design of materials with a specific dielectric response. For
+the opposite case of linear arrays in a large network, where periodic boundary
+condition do not apply, several asymptotic properties are derived. Throughout
+the article, the derived analytic results are compared to numerical models,
+based on either Exact Numerical Renormalisation or the spectral method.",0501137v1
+2005-07-27,"""Stochastic Modeling of Coercivity "" - A Measure of Non-equilibrium State","A typical coercivity versus particle size curve for magnetic nanoparticles
+has been explained by using the Gilbert equation followed by the corresponding
+Fokker Plank equation. Kramer's treatment has been employed to explain the
+increase in coercivity in the single domain region. The single to multi-domain
+transformation has been assumed to explain the decrease in coercive field
+beyond a certain particle size. The justification for using Langevin theory of
+paramagnetism (including anisotropy energy) to fit the M vs H curve is
+discussed. The super-symmetric Hamiltonian approach is used to find out the
+relaxation time for the spins (making an angle greater than $90^0$ with applied
+field) at domain wall. The main advantage of our technique is that we can
+easily take into account the time of measurement as we usually do in realistic
+measurement.",0507640v1
+2005-09-13,Synchronization of spin-transfer oscillators driven by stimulated microwave currents,"We have simulated the non-linear dynamics of networks of spin-transfer
+oscillators. The oscillators are magnetically uncoupled but electrically
+connected in series. We use a modified Landau-Lifschitz- Gilbert equation to
+describe the motion of each oscillator in the presence of the oscillations of
+all the others. We show that the oscillators of the network can be synchronized
+not only in frequency but also in phase. The coupling is due to the microwave
+components of the current induced in each oscillator by the oscillations in all
+the other oscillators. Our results show how the emitted microwave power of
+spin-transfer oscillators can be considerably enhanced by current-induced
+synchronization in an electrically connected network. We also discuss the
+possible application of our synchronization mechanism to the interpretation of
+the surprisingly narrow microwave spectrum in some isolated spin-transfer
+oscillators.",0509326v2
+2005-11-04,Synchronized Magnetization Oscillations in F/N/F Nanopillars,"Current-induced magnetization dynamics in a trilayer structure composed of
+two ferromagnetic free layers and a nonmagnetic spacer is examined. Both free
+layers are treated as a monodomain magnetic body with an uniform agnetization.
+The dynamics of the two magnetizations is modeled by modified
+Landau-Lifshitz-Gilbert equations with spin-transfer torque terms. By solving
+the equations simultaneously, we discuss their various solutions in detail. We
+show that there exists the synchronous motion of two magnetizations among the
+various solutions; the magnetizations are resonantly coupled via spin-transfer
+torques and perform precessional motions with the same period. The condition to
+excite the synchronous motion depends on the difference between the intrinsic
+frequencies of the two ferromagnetic free layers as well as the magnitude of
+current.",0511095v1
+2006-01-27,Dynamics of thin-film spin-flip transistors with perpendicular source-drain magnetizations,"A ""spin-flip transistor"" is a lateral spin valve consisting of ferromagnetic
+source drain contacts to a thin-film normal-metal island with an electrically
+floating ferromagnetic base contact on top. We analyze the
+\emph{dc}-current-driven magnetization dynamics of spin-flip transistors in
+which the source-drain contacts are magnetized perpendicularly to the device
+plane by magnetoelectronic circuit theory and the macrospin
+Landau-Lifshitz-Gilbert equation. Spin flip scattering and spin pumping effects
+are taken into account. We find a steady-state rotation of the base
+magnetization at GHz frequencies that is tuneable by the source-drain bias. We
+discuss the advantages of the lateral structure for high-frequency generation
+and actuation of nanomechanical systems over recently proposed nanopillar
+structures.",0601630v1
+2007-03-17,Large-amplitude coherent spin waves exited by spin-polarized current in nanoscale spin valves,"We present spectral measurements of spin-wave excitations driven by direct
+spinpolarized current in the free layer of nanoscale
+Ir20Mn80/Ni80Fe20/Cu/Ni80Fe20 spin valves. The measurements reveal that
+large-amplitude coherent spin wave modes are excited over a wide range of bias
+current. The frequency of these excitations exhibits a series of jumps as a
+function of current due to transitions between different localized nonlinear
+spin wave modes of the Ni80Fe20 nanomagnet. We find that micromagnetic
+simulations employing the Landau-Lifshitz-Gilbert equation of motion augmented
+by the Slonczewski spin torque term (LLGS) accurately describe the frequency of
+the current-driven excitations including the mode transition behavior. However
+LLGS simulations give qualitatively incorrect predictions for the amplitude of
+excited spin waves as a function of current.",0703458v2
+2001-12-11,A Data Mining Framework for Optimal Product Selection in Retail Supermarket Data: The Generalized PROFSET Model,"In recent years, data mining researchers have developed efficient association
+rule algorithms for retail market basket analysis. Still, retailers often
+complain about how to adopt association rules to optimize concrete retail
+marketing-mix decisions. It is in this context that, in a previous paper, the
+authors have introduced a product selection model called PROFSET. This model
+selects the most interesting products from a product assortment based on their
+cross-selling potential given some retailer defined constraints. However this
+model suffered from an important deficiency: it could not deal effectively with
+supermarket data, and no provisions were taken to include retail category
+management principles. Therefore, in this paper, the authors present an
+important generalization of the existing model in order to make it suitable for
+supermarket data as well, and to enable retailers to add category restrictions
+to the model. Experiments on real world data obtained from a Belgian
+supermarket chain produce very promising results and demonstrate the
+effectiveness of the generalized PROFSET model.",0112013v1
+2005-02-22,The QuarkNet/Grid Collaborative Learning e-Lab,"We describe a case study that uses grid computing techniques to support the
+collaborative learning of high school students investigating cosmic rays.
+Students gather and upload science data to our e-Lab portal. They explore those
+data using techniques from the GriPhyN collaboration. These techniques include
+virtual data transformations, workflows, metadata cataloging and indexing, data
+product provenance and persistence, as well as job planners. Students use web
+browsers and a custom interface that extends the GriPhyN Chiron portal to
+perform all of these tasks. They share results in the form of online posters
+and ask each other questions in this asynchronous environment. Students can
+discover and extend the research of other students, modeling the processes of
+modern large-scale scientific collaborations. Also, the e-Lab portal provides
+tools for teachers to guide student work throughout an investigation.
+http://quarknet.uchicago.edu/elab/cosmic",0502089v1
+2006-10-11,Properties of codes in rank metric,"We study properties of rank metric and codes in rank metric over finite
+fields. We show that in rank metric perfect codes do not exist. We derive an
+existence bound that is the equivalent of the Gilbert--Varshamov bound in
+Hamming metric. We study the asymptotic behavior of the minimum rank distance
+of codes satisfying GV. We derive the probability distribution of minimum rank
+distance for random and random $\F{q}$-linear codes. We give an asymptotic
+equivalent of their average minimum rank distance and show that random
+$\F{q}$-linear codes are on GV bound for rank metric.
+  We show that the covering density of optimum codes whose codewords can be
+seen as square matrices is lower bounded by a function depending only on the
+error-correcting capability of the codes. We show that there are quasi-perfect
+codes in rank metric over fields of characteristic 2.",0610057v1
+1995-12-28,MSSM radiative contributions to the WW$γ$ and WWZ form factors,"We evaluate one-loop contributions to the C and P conserving $WW\gamma, WWZ$
+form factors in the Minimal Supersymmetric Standard Model (MSSM), and in a more
+constrained Supergravity Grand Unified Theory (SUGRA-GUT). A systematic search
+of maximal effects in the available parameter space, shows that at LEP2 energy
+MSSM contributions can hardly reach the border of the most optimistic accuracy
+expected on those couplings, even for particles close to their production
+thresholds. At NLC energies, the effects are more comfortably of the order of
+the expected sensitivity, and may therefore provide useful information on MSSM
+parameter values which will not be available from direct particle production.
+We also discuss briefly some variance with other studies.",9512437v2
+1998-07-10,Inverting the Supersymmetric Standard Model Spectrum: from Physical to Lagrangian Ino Parameters,"We examine the possibility of recovering the supersymmetric (and soft
+supersymmetry breaking) Lagrangian parameters as direct {\em analytical}
+expressions of appropriate physical masses, for the unconstrained (but CP and
+R-parity conserving) minimal supersymmetric standard model. We concentrate
+mainly on the algebraically non-trivial ""inversion"" for the ino parameters, and
+obtain, for given values of $\tan\beta$, simple analytical expressions for the
+$\mu$, $M_1$ and $M_2$ parameters in terms of three arbitrary input physical
+masses, namely either two chargino and one neutralino masses, or alternatively
+one chargino and two neutralino masses. We illustrate and discuss in detail the
+possible occurrence of ambiguities in this reconstruction. The dependence of
+the resulting ino Lagrangian parameters upon physical masses is illustrated,
+and some simple generic behaviour uncovered in this way. We finally briefly
+sketch generalizing such an inversion to the full set of MSSM Lagrangian
+parameters.",9807336v2
+1999-07-01,A convergent scheme for one-loop evolutions of the Yukawa couplings in the MSSM,"Integrated forms of the one-loop evolution equations are given for the Yukawa
+couplings in the MSSM, valid for any value of $\tan \beta$, generalizable to
+virtually any number of Yukawa fermions, and including all gauge couplings.
+These forms turn out to have nice mathematical convergence properties which we
+prove, and we determine the ensuing convergence criteria. Furthermore, they
+allow to write down general sufficient and necessary conditions to avoid
+singularities in the evolution of the Yukawa couplings over physically relevant
+energy ranges. We also comment briefly on the possible use of these features
+for physics issues and give a short numerical illustration.",9907204v1
+1999-07-14,Phases in the gaugino sector: direct reconstruction of the basic parameters and impact on the neutralino pair production,"We consider recovering analytically the (generally complex) parameters $\mu$,
+$M_1$ and $M_2$ of the gaugino and Higgsino Lagrangian, from appropriate
+physical input in the chargino and neutralino sectors. For given $\tan\beta$,
+we obtain very simple analytic solutions for $M_2$, $| \mu|$, $Arg[\mu]$ in the
+chargino sector and a twofold $| M_1 |$, $Arg[M_1]$ analytic solution in the
+neutralino sector, assuming two chargino, two neutralino masses, and one of the
+chargino mixing angles as physical input. The twofold ambiguity in the
+neutralino parameters reconstruction may be essentially resolved by measuring
+the $e^+e^- \to \chi^0_1 \chi^0_2$ production cross-section at future linear
+collider energies, which we study explicitly with the phase dependences. Some
+salient features and specific properties of this complex case gaugino ""spectrum
+inversion"" are illustrated and compared with the similar inversion in the real
+case. In particular, our algorithms exhibit in a direct and transparent way the
+non-trivial theoretical correlation among the chargino and neutralino
+parameters, and the resulting allowed domains when only a subset of the
+required physical input masses and production cross-sections is known.",9907360v1
+1999-12-08,Analytical Study of Non-Universality of the Soft Terms in the MSSM,"We obtain general analytical forms for the solutions of the one-loop
+renormalization group equations in the top/bottom/$\tau$ sector of the MSSM.
+These solutions are valid for any value of $\tan \beta$ as well as any
+non-universal initial conditions for the soft SUSY breaking parameters and
+non-unification of the Yukawa couplings. We establish analytically a generic
+screening effect of non-universality, in the vicinity of the infrared quasi
+fixed point, which allows to determine sector-wise a hierarchy of sensitivity
+to initial conditions. We give also various numerical illustrations of this
+effect away from the quasi fixed point and assess the sensitivity of the Higgs
+and sfermion spectra to the non-universality of the various soft breaking
+sectors. As a by-product, a typical anomaly-mediated non-universality of the
+gaugino sector would have marginal influence on the scalar spectrum.",9912271v1
+2001-01-22,General one-loop renormalization group evolutions and electroweak symmetry breaking in the (M+1)SSM,"We study analytically the general features of electroweak symmetry breaking
+in the context of the Minimal Supersymmetric Standard Model extended by one
+Higgs singlet. The exact analytical forms of the renormalization group
+evolutions of the Yukawa couplings and of the soft supersymmetry breaking
+parameters are derived to one-loop order. They allow on one hand controllable
+approximations in closed analytical form, and on the other a precise study of
+the behaviour of infrared quasi fixed point regimes which we carry out. Some of
+these regimes are shown to be phenomenologically inconsistent, leading to too
+small an effective $\mu$-parameter. The remaining ones serve as a suitable
+benchmark to understand analytically some salient aspects, often noticed
+numerically in the literature, in relation to the electroweak symmetry breaking
+in this model. The study does not need any specific assumption on $\tan \beta$
+or on boundary conditions for the soft supersymmetry breaking parameters, thus
+allowing a general insight into the sensitivity of the low energy physics to
+high energy assumptions.",0101237v1
+2001-12-28,Infrared Quasi Fixed Point Structure in Extended Yukawa Sectors and Application to R-parity Violation,"We investigate one-loop renormalization group evolutions of extended sectors
+of Yukawa type couplings. It is shown that Landau Poles which usually provide
+necessary low energy upper bounds that saturate quickly with increasing initial
+value conditions, lead in some cases to the opposite behaviour: some of the low
+energy couplings decrease and become vanishingly small for increasingly large
+initial conditions. We write down the general criteria for this to happen in
+typical situations, highlighting a concept of {\sl repulsive} quasi-fixed
+points, and illustrate the case both within a two-Yukawa toy model as well as
+in the minimal supersymmetric standard model with R-parity violation. In the
+latter case we consider the theoretical upper bounds on the various couplings,
+identifying regimes where $\lambda_{kl3}, \lambda'_{kkk}, \lambda''_{3kl}$ are
+dynamically suppressed due to the Landau Pole. We stress the importance of
+considering a large number of couplings simultaneously. This leads altogether
+to a phenomenologically interesting seesaw effect in the magnitudes of the
+various R-parity violating couplings, complementing and in some cases improving
+the existing limits.",0112353v1
+2005-04-04,Natural gravitino dark matter in SO(10) gauge mediated supersymmetry breaking,"It is shown that gravitinos with mass m_{3/2} ~ 0.1-1 MeV may provide
+suitable cold dark matter candidates in scenarios of gauge mediated
+supersymmetry breaking (GMSB) under SO(10) grand unification coupled to
+supergravity, which accommodate a messenger sector of mass scale M_X ~ 10^6
+GeV. This is due to the combined effects of renormalizable loop-suppressed
+operators and generic non-renormalizable ones governing the dilution of a
+pre-existing equilibrium gravitino abundance via messenger decay. The above
+range of gravitino and messenger masses can be accommodated in indirect GMSB
+scenarios. The gravitino abundance does not depend on the post-inflationary
+reheat temperature and it is shown that leptogenesis can generate successfully
+the baryon asymmetry.",0504021v2
+2005-06-14,Gravitino dark matter in gauge mediated supersymmetry breaking,"This paper investigates the parameter space of theories with gauge mediated
+supersymmetry breaking leading to gravitino (cold) dark matter with mass
+m_{3/2}= 1keV - 10MeV. We pay particular attention to the cosmological role of
+messenger fields. Cosmology requires that these messengers decay to the visible
+sector if the lightest messenger mass M_X > 30TeV. We then examine the various
+possible messenger number violating interactions allowed by the symmetries of
+the theory and by phenomenology. Late messenger decay generally results in
+entropy production hence in the dilution of pre-existing gravitinos. We find
+that in SU(5) grand unification only specific messenger-matter couplings allow
+to produce the required amount of gravitino dark matter particles. Gravitino
+dark matter with the correct abundance is however expected in larger gauge
+groups such as SO(10) for generic non-renormalizable messenger-matter
+interactions and for arbritrarily high post-inflationary reheating
+temperatures.",0506129v2
+1991-08-22,On the Perturbations of String-Theoretic Black Holes,"The perturbations of string-theoretic black holes are analyzed by
+generalizing the method of Chandrasekhar. Attention is focussed on the case of
+the recently considered charged string-theoretic black hole solutions as a
+representative example. It is shown that string-intrinsic effects greatly alter
+the perturbed motions of the string-theoretic black holes as compared to the
+perturbed motions of black hole solutions of the field equations of general
+relativity, the consequences of which bear on the questions of the scattering
+behavior and the stability of string-theoretic black holes. The explicit forms
+of the axial potential barriers surrounding the string-theoretic black hole are
+derived. It is demonstrated that one of these, for sufficiently negative values
+of the asymptotic value of the dilaton field, will inevitably become negative
+in turn, in marked contrast to the potentials surrounding the static black
+holes of general relativity. Such potentials may in principle be used in some
+cases to obtain approximate constraints on the value of the string coupling
+constant. The application of the perturbation analysis to the case of
+two-dimensional string-theoretic black holes is discussed.",9108012v1
+1992-10-31,All Or Nothing: On the Small Fluctuations of Two-Dimensional String-Theoretic Black Holes,"A comprehensive analysis of small fluctuations about two-dimensional
+string-theoretic and string-inspired black holes is presented. It is shown with
+specific examples that two-dimensional black holes behave in a radically
+different way from all known black holes in four dimensions. For both the
+$SL(2,R)/U(1)$ black hole and the two-dimensional black hole coupled to a
+massive dilaton with constant field strength, it is shown that there are a {\it
+continuous infinity} of solutions to the linearized equations of motion, which
+are such that it is impossible to ascertain the classical linear response. It
+is further shown that the two-dimensional black hole coupled to a massive,
+linear dilaton admits {\it no small fluctuations at all}. We discuss possible
+implications of our results for the Callan-Giddings-Harvey-Strominger black
+hole.",9210165v3
+1998-04-24,Enumeration of m-ary cacti,"The purpose of this paper is to enumerate various classes of cyclically
+colored m-gonal plane cacti, called m-ary cacti. This combinatorial problem is
+motivated by the topological classification of complex polynomials having at
+most m critical values, studied by Zvonkin and others. We obtain explicit
+formulae for both labelled and unlabelled m-ary cacti, according to i) the
+number of polygons, ii) the vertex-color distribution, iii) the vertex-degree
+distribution of each color. We also enumerate m-ary cacti according to the
+order of their automorphism group. Using a generalization of Otter's formula,
+we express the species of m-ary cacti in terms of rooted and of pointed cacti.
+A variant of the m-dimensional Lagrange inversion is then used to enumerate
+these structures. The method of Liskovets for the enumeration of unrooted
+planar maps can also be adapted to m-ary cacti.",9804119v2
+2002-08-21,Toric codes over finite fields,"In this note, a class of error-correcting codes is associated to a toric
+variety associated to a fan defined over a finite field $\fff_q$, analogous to
+the class of Goppa codes associated to a curve. For such a ``toric code''
+satisfying certain additional conditions, we present an efficient decoding
+algorithm for the dual of a Goppa code. Many examples are given. For small $q$,
+many of these codes have parameters beating the Gilbert-Varshamov bound. In
+fact, using toric codes, we construct a $(n,k,d)=(49,11,28)$ code over
+$\fff_8$, which is better than any other known code listed in Brouwer's on-line
+tables for that $n$ and $k$.",0208155v2
+2002-12-05,Automorphisms of hyperbolic groups and graphs of groups,"Using the canonical JSJ splitting, we describe the outer automorphism group
+$\Out(G)$ of a one-ended word hyperbolic group $G$. In particular, we discuss
+to what extent $\Out(G)$ is virtually a direct product of mapping class groups
+and a free abelian group, and we determine for which groups $\Out(G)$ is
+infinite. We also show that there are only finitely many conjugacy classes of
+torsion elements in $\Out(G)$, for $G$ any torsion-free hyperbolic group.
+  More generally, let $\Gamma $ be a finite graph of groups decomposition of an
+arbitrary group $G$ such that edge groups $G_e$ are rigid (i.e\. $\Out(G_e)$ is
+finite). We describe the group of automorphisms of $G$ preserving $\Gamma $, by
+comparing it to direct products of suitably defined mapping class groups of
+vertex groups.",0212088v1
+2004-06-08,"The structure and labelled enumeration of K_{3,3}-subdivision-free projective-planar graphs","We consider the class F of 2-connected non-planar K_{3,3}-subdivision-free
+graphs that are embeddable in the projective plane. We show that these graphs
+admit a unique decomposition as a graph K_5 (the core) where the edges are
+replaced by two-pole networks constructed from 2-connected planar graphs. A
+method to enumerate these graphs in the labelled case is described. Moreover,
+we enumerate the homeomorphically irreducible graphs in F and homeomorphically
+irreducible 2-connected planar graphs. Particular use is made of two-pole
+directed series-parallel networks. We also show that the number m of edges of
+graphs in F with n vertices satisfies the bound m <=3n-6, for n >= 6.",0406140v5
+2004-09-16,Translation equivalence in free groups,"Motivated by the work of Leininger on hyperbolic equivalence of homotopy
+classes of closed curves on surfaces, we investigate a similar phenomenon for
+free groups. Namely, we study the situation when two elements $g,h$ in a free
+group $F$ have the property that for every free isometric action of $F$ on an
+$\mathbb{R}$-tree $X$ the translation lengths of $g$ and $h$ on $X$ are equal.
+We give a combinatorial characterization of this phenomenon, called translation
+equivalence, in terms of Whitehead graphs and exhibit two difference sources of
+it. The first source of translation equivalence comes from representation
+theory and $SL_2$ trace identities. The second source comes from geometric
+properties of groups acting on real trees and a certain power redistribution
+trick. We also analyze to what extent these are applicable to the tree actions
+of surface groups that occur in the Thurston compactification of the
+Teichmuller space.",0409284v2
+2004-11-16,"Characterization and enumeration of toroidal K_{3,3}-subdivision-free graphs","We describe the structure of 2-connected non-planar toroidal graphs with no
+K_{3,3}-subdivisions, using an appropriate substitution of planar networks into
+the edges of certain graphs called toroidal cores. The structural result is
+based on a refinement of the algorithmic results for graphs containing a fixed
+K_5-subdivision in [A. Gagarin and W. Kocay, ""Embedding graphs containing
+K_5-subdivisions'', Ars Combin. 64 (2002), 33-49]. It allows to recognize these
+graphs in linear-time and makes possible to enumerate labelled 2-connected
+toroidal graphs containing no K_{3,3}-subdivisions and having minimum vertex
+degree two or three by using an approach similar to [A. Gagarin, G. Labelle,
+and P. Leroux, ""Counting labelled projective-planar graphs without a
+K_{3,3}-subdivision"", submitted, arXiv:math.CO/0406140, (2004)].",0411356v1
+2005-01-19,The outer space of a free product,"We associate a contractible ``outer space'' to any free product of groups
+G=G_1*...*G_q. It equals Culler-Vogtmann space when G is free,
+McCullough-Miller space when no G_i is Z. Our proof of contractibility (given
+when G is not free) is based on Skora's idea of deforming morphisms between
+trees.
+  Using the action of Out(G) on this space, we show that Out(G) has finite
+virtual cohomological dimension, or is VFL (it has a finite index subgroup with
+a finite classifying space), if the groups G_i and Out(G_i) have similar
+properties. We deduce that Out(G) is VFL if G is a torsion-free hyperbolic
+group, or a limit group (finitely generated fully residually free group).",0501288v3
+2005-07-28,"Free-group automorphisms, train tracks and the beaded decomposition","We study the automorphisms \phi of a finitely generated free group F.
+Building on the train-track technology of Bestvina, Feighn and Handel, we
+provide a topological representative f:G\to G of a power of \phi that behaves
+very much like the realization on the rose of a positive automorphism. This
+resemblance is encapsulated in the Beaded Decomposition Theorem which describes
+the structure of paths in G obtained by repeatedly passing to f-images of an
+edge and taking subpaths. This decomposition is the key to adapting our proof
+of the quadratic isoperimetric inequality for $F\rtimes_\phi\mathbb Z$, with
+\phi positive, to the general case. To illustrate the wider utility of our
+topological normal form, we provide a short proof that for every w in F, the
+function $n\mapsto |\phi^n(w)|$ grows either polynomially or exponentially.",0507589v2
+2007-02-02,Line-of-sight percolation,"Given $\omega\ge 1$, let $Z^2_{(\omega)}$ be the graph with vertex set $Z^2$
+in which two vertices are joined if they agree in one coordinate and differ by
+at most $\omega$ in the other. (Thus $Z^2_{(1)}$ is precisely $Z^2$.) Let
+$p_c(\omega)$ be the critical probability for site percolation in
+$Z^2_{(\omega)}$. Extending recent results of Frieze, Kleinberg, Ravi and
+Debany, we show that $\lim_{\omega\to\infty} \omega\pc(\omega)=\log(3/2)$. We
+also prove analogues of this result on the $n$-by-$n$ grid and in higher
+dimensions, the latter involving interesting connections to Gilbert's continuum
+percolation model. To prove our results, we explore the component of the origin
+in a certain non-standard way, and show that this exploration is well
+approximated by a certain branching random walk.",0702061v2
+2000-03-06,"Entropy Production, Fractals, and Relaxation to Equilibrium","The theory of entropy production in nonequilibrium, Hamiltonian systems,
+previously described for steady states using partitions of phase space, is here
+extended to time dependent systems relaxing to equilibrium. We illustrate the
+main ideas by using a simple multibaker model, with some nonequilibrium initial
+state, and we study its progress toward equilibrium. The central results are
+(i) the entropy production is governed by an underlying, exponentially decaying
+fractal structure in phase space, (ii) the rate of entropy production is
+largely independent of the scale of resolution used in the partitions, and
+(iii) the rate of entropy production is in agreement with the predictions of
+nonequilibrium thermodynamics.",0003012v2
+2002-03-21,Entropy production of diffusion in spatially periodic deterministic systems,"This paper presents an {\it ab initio} derivation of the expression given by
+irreversible thermodynamics for the rate of entropy production for different
+classes of diffusive processes. The first class are Lorentz gases, where
+non-interacting particles move on a spatially periodic lattice, and collide
+elastically with fixed scatterers. The second class are periodic systems where
+$N$ particles interact with each other, and one of them is a tracer particle
+which diffuses among the cells of the lattice. We assume that, in either case,
+the dynamics of the system is deterministic and hyperbolic, with positive
+Lyapunov exponents. This work extends methods originally developed for a
+chaotic two-dimensional model of diffusion, the multi-baker map, to higher
+dimensional, continuous time dynamical systems appropriate for systems with one
+or more moving particles. Here we express the rate of entropy production in
+terms of hydrodynamic measures that are determined by the fractal properties of
+microscopic hydrodynamic modes that describe the slowest decay of the system to
+an equilibrium state.",0203046v1
+2001-11-09,Spatial diffusion in a periodic optical lattice: revisiting the Sisyphus effect,"We numerically study the spatial diffusion of an atomic cloud experiencing
+Sisyphus cooling in a three-dimensional lin$\bot$lin optical lattice in a broad
+range of lattice parameters. In particular, we investigate the dependence on
+the size of the lattice sites which changes with the angle between the laser
+beams. We show that the steady-state temperature is largely independent of the
+lattice angle, but that the spatial diffusion changes significantly. It is
+shown that the numerical results fulfil the Einstein relations of Brownian
+motion in the jumping regime as well as in the oscillating regime. We finally
+derive an effective Brownian motion model from first principles which gives
+good agreement with the simulations.",0111070v2
+2006-07-24,Use of specific Green's functions for solving direct problems involving a heterogeneous rigid frame porous medium slab solicited by acoustic waves,"A domain integral method employing a specific Green's function (i.e.,
+incorporating some features of the global problem of wave propagation in an
+inhomogeneous medium) is developed for solving direct and inverse scattering
+problems relative to slab-like macroscopically inhomogeneous porous obstacles.
+It is shown how to numerically solve such problems, involving both
+spatially-varying density and compressibility, by means of an iterative scheme
+initialized with a Born approximation. A numerical solution is obtained for a
+canonical problem involving a two-layer slab.",0607212v1
+2005-12-12,"Cloning, expression and purification of the general stress protein Yhbo from Escherichia coli","We cloned, expressed and purified the Escherichia coli yhbO gene product,
+which is homolog to the Bacillus subtilis general stress protein 18 (the yfkM
+gene product), the Pyrococcus furiosus intracellular protease PfpI, and the
+human Parkinson disease protein DJ-1. The gene coding for YhbO was generated by
+amplifying the yhbO gene from E. coli by polymerase chain reaction. It was
+inserted in the expression plasmid pET-21a, under the transcriptional control
+of the bacteriophage T7 promoter and lac operator. A BL21(DE3) E. coli strain
+transformed with the YhbO-expression vector pET-21a-yhbO, accumulates large
+amounts of a soluble protein of 20 kDa in SDS-PAGE that matches the expected
+YhbO molecular weight. YhbO was purified to homogeneity by HPLC DEAE ion
+exchange chromatography and hydroxylapatite chromatography and its identity was
+confirmed by N-terminal sequencing and mass spectrometry analysis. The native
+protein exists in monomeric, trimeric and hexameric forms.",0512028v1
+2003-01-24,Rayleigh Scattering and Atomic Dynamics in Dissipative Optical Lattices,"We investigate Rayleigh scattering in dissipative optical lattices. In
+particular, following recent proposals (S. Guibal {\it et al}, Phys. Rev. Lett.
+{\bf 78}, 4709 (1997); C. Jurczak {\it et al}, Phys. Rev. Lett. {\bf 77}, 1727
+(1996)), we study whether the Rayleigh resonance originates from the
+diffraction on a density grating, and is therefore a probe of transport of
+atoms in optical lattices. It turns out that this is not the case: the Rayleigh
+line is instead a measure of the cooling rate, while spatial diffusion
+contributes to the scattering spectrum with a much broader resonance.",0301139v1
+2005-12-19,More on the Asymmetric Infinite Square Well: Energy Eigenstates with Zero Curvature,"We extend the standard treatment of the asymmetric infinite square well to
+include solutions that have zero curvature over part of the well. This type of
+solution, both within the specific context of the asymmetric infinite square
+well and within the broader context of bound states of arbitrary
+piecewise-constant potential energy functions, is not often discussed as part
+of quantum mechanics texts at any level. We begin by outlining the general
+mathematical condition in one-dimensional time-independent quantum mechanics
+for a bound-state wave function to have zero curvature over an extended region
+of space and still be a valid wave function. We then briefly review the
+standard asymmetric infinite square well solutions, focusing on zero-curvature
+solutions as represented by energy eigenstates in position and momentum space.",0512156v1
+2006-05-09,Communicating over adversarial quantum channels using quantum list codes,"We study quantum communication in the presence of adversarial noise. In this
+setting, communicating with perfect fidelity requires using a quantum code of
+bounded minimum distance, for which the best known rates are given by the
+quantum Gilbert-Varshamov (QGV) bound. By asking only for arbitrarily high
+fidelity and allowing the sender and reciever to use a secret key with length
+logarithmic in the number of qubits sent, we achieve a dramatic improvement
+over the QGV rates. In fact, we find protocols that achieve arbitrarily high
+fidelity at noise levels for which perfect fidelity is impossible. To achieve
+such communication rates, we introduce fully quantum list codes, which may be
+of independent interest.",0605086v2
+2007-05-16,Quantization Bounds on Grassmann Manifolds of Arbitrary Dimensions and MIMO Communications with Feedback,"This paper considers the quantization problem on the Grassmann manifold with
+dimension n and p. The unique contribution is the derivation of a closed-form
+formula for the volume of a metric ball in the Grassmann manifold when the
+radius is sufficiently small. This volume formula holds for Grassmann manifolds
+with arbitrary dimension n and p, while previous results are only valid for
+either p=1 or a fixed p with asymptotically large n. Based on the volume
+formula, the Gilbert-Varshamov and Hamming bounds for sphere packings are
+obtained. Assuming a uniformly distributed source and a distortion metric based
+on the squared chordal distance, tight lower and upper bounds are established
+for the distortion rate tradeoff. Simulation results match the derived results.
+As an application of the derived quantization bounds, the information rate of a
+Multiple-Input Multiple-Output (MIMO) system with finite-rate channel-state
+feedback is accurately quantified for arbitrary finite number of antennas,
+while previous results are only valid for either Multiple-Input Single-Output
+(MISO) systems or those with asymptotically large number of transmit antennas
+but fixed number of receive antennas.",0705.2272v1
+2007-05-24,Local spin dynamic arising from the non-perturbative SU(2) gauge field of the spin orbit effect,"We use the non-perturbative gauge field approach to study the effects of spin
+orbit coupling on the dynamic of magnetic moment. We present a general equation
+of motion (EOM) which unifies i) the spin orbit coupling effect derived from
+the SU(2) spin gauge field, and ii) the moment chirality effect previously
+derived from the topological U(1)xU(1) rotation gauge under the adiabatic
+condition. We present a modified Landau-Liftshitz-Gilbert equation and discuss
+the implication of the modified EOM in various technological applications, such
+as current-induced switching and trajectory of magnetic moments in spin-valve
+multilayers, magnetic memory and diluted magnetic semiconductor.",0705.3502v1
+2007-06-07,$^{77}$Se NMR measurements of the $π-d$ exchange field in the organic conductor $λ-$(BETS)$_{2}$FeCl$_{4}$,"$^{77}$Se-NMR spectrum and frequency shift measurements in the paramagnetic
+metal (PM) and antiferromagnetic insulating (AFI) phases are reported for a
+small single crystal of the organic conductor $\lambda-$(BETS)$_{2}$FeCl$_{4}$
+as a function of temperature ($T$) and field alignment for an applied magnetic
+field $B_{0}$ = 9 T. The results show that in the low $T$ limit, where the
+localized Fe$^{3+}$ spins ($S_{d}$ = 5/2) are almost fully polarized, the
+conduction electrons (Se $\pi$-electrons, spin $s_{\pi}$ = 1/2) in the BETS
+molecules experience an exchange field ($\bf{B}$$_{\pi d}$) from the Fe$^{3+}$
+spins with a value of $-$ 32.7 $\pm$ 1.5 T at 5 K and 9 T aligned opposite to
+$\bf{B}$$_{0}$. This large negative value of $\bf{B}$$_{\pi d}$ is consistent
+with that predicted by the resistivity measurements and supports the
+Jaccarino-Peter internal field-compensation mechanism being responsible for the
+origin of field-induced superconductivity.",0706.0933v1
+2007-11-05,Feedback Capacity of the Compound Channel,"In this work we find the capacity of a compound finite-state channel with
+time-invariant deterministic feedback. The model we consider involves the use
+of fixed length block codes. Our achievability result includes a proof of the
+existence of a universal decoder for the family of finite-state channels with
+feedback. As a consequence of our capacity result, we show that feedback does
+not increase the capacity of the compound Gilbert-Elliot channel. Additionally,
+we show that for a stationary and uniformly ergodic Markovian channel, if the
+compound channel capacity is zero without feedback then it is zero with
+feedback. Finally, we use our result on the finite-state channel to show that
+the feedback capacity of the memoryless compound channel is given by
+$\inf_{\theta} \max_{Q_X} I(X;Y|\theta)$.",0711.0705v1
+2007-11-12,Mutual phase-locking in high frequency microwave nanooscillators as function of field angle,"We perform a qualitative analysis of phase locking in a double point-contact
+spinvalve system by solving the Landau-Lifshitz-Gilbert-Slonzewski equation
+using a hybrid-finite-element method. We show that the phase-locking behaviour
+depends on the applied field angle. Starting from a low field angle, the
+locking-current difference between the current through contact A and B
+increases with increasing angle up to a maximum of 14 mA at 30 degree and it
+decreases thereafter until it reaches a minimum of 1 mA at 75 degree. The
+tunability of the phase-lock frequency with current decreases linearly with
+increasing out of plane angle from 45 to 21 MHz/mA.",0711.1770v2
+2007-11-14,Emergent singular solutions of non-local density-magnetization equations in one dimension,"We investigate the emergence of singular solutions in a non-local model for a
+magnetic system. We study a modified Gilbert-type equation for the
+magnetization vector and find that the evolution depends strongly on the length
+scales of the non-local effects. We pass to a coupled density-magnetization
+model and perform a linear stability analysis, noting the effect of the length
+scales of non-locality on the system's stability properties. We carry out
+numerical simulations of the coupled system and find that singular solutions
+emerge from smooth initial data. The singular solutions represent a collection
+of interacting particles (clumpons). By restricting ourselves to the
+two-clumpon case, we are reduced to a two-dimensional dynamical system that is
+readily analyzed, and thus we classify the different clumpon interactions
+possible.",0711.2177v1
+2007-11-27,Nonequilibrium interacting electrons in a ferromagnet,"Dynamics of the magnetization in ferromagnets is examined in the presence of
+transport electrons allowing the latter to interact. It is found that the
+existence of inhomogeneities such as domain wall (DW) structures, leads to
+changes that affect the dynamical structure of the equations of motion for the
+magnetization. Only in the limit of uniform magnetizations or sufficiently wide
+DW's, the equations of motion maintain the form they have in the noninteracting
+case. In this limit, results like the spin torques, the Gilbert parameter, and
+the DW velocities become renormalized. However the length scale that defines
+such a limit depends on the strength of the interaction. It is shown that if
+large ferromagnetic fluctuations exist in the metallic band then the range for
+which conformity with the noninteracting case holds extends to the limit of
+arbitrarily narrow DW's.",0711.4170v2
+2007-12-01,On Precision - Redundancy Relation in the Design of Source Coding Algorithms,"We study the effects of finite-precision representation of source's
+probabilities on the efficiency of classic source coding algorithms, such as
+Shannon, Gilbert-Moore, or arithmetic codes. In particular, we establish the
+following simple connection between the redundancy $R$ and the number of bits
+$W$ necessary for representation of source's probabilities in computer's memory
+($R$ is assumed to be small): \begin{equation*} W \lesssim \eta \log_2
+\frac{m}{R}, \end{equation*} where $m$ is the cardinality of the source's
+alphabet, and $\eta \leqslant 1$ is an implementation-specific constant. In
+case of binary alphabets ($m=2$) we show that there exist codes for which $\eta
+= 1/2$, and in $m$-ary case ($m > 2$) we show that there exist codes for which
+$\eta = m/(m+1)$. In general case, however (which includes designs relying on
+progressive updates of frequency counters), we show that $\eta = 1$. Usefulness
+of these results for practical designs of source coding algorithms is also
+discussed.",0712.0057v1
+2007-12-03,Kinetic models of heterogeneous dissipation,"We suggest kinetic models of dissipation for an ensemble of interacting
+oriented particles, for example, moving magnetized particles. This is achieved
+by introducing a double bracket dissipation in kinetic equations using an
+oriented Poisson bracket, and employing the moment method to derive continuum
+equations for magnetization and density evolution. We show how our continuum
+equations generalize the Debye-Hueckel equations for attracting round
+particles, and Landau-Lifshitz-Gilbert equations for spin waves in magnetized
+media. We also show formation of singular solutions that are clumps of aligned
+particles (orientons) starting from random initial conditions. Finally, we
+extend our theory to the dissipative motion of self-interacting curves.",0712.0397v1
+2007-12-13,Euler equation of the optimal trajectory for the fastest magnetization reversal of nano-magnetic structures,"Based on the modified Landau-Lifshitz-Gilbert equation for an arbitrary
+Stoner particle under an external magnetic field and a spin-polarized electric
+current, differential equations for the optimal reversal trajectory, along
+which the magnetization reversal is the fastest one among all possible reversal
+routes, are obtained. We show that this is a Euler-Lagrange problem with
+constrains. The Euler equation of the optimal trajectory is useful in designing
+a magnetic field pulse and/or a polarized electric current pulse in
+magnetization reversal for two reasons. 1) It is straightforward to obtain the
+solution of the Euler equation, at least numerically, for a given magnetic
+nano-structure characterized by its magnetic anisotropy energy. 2) After
+obtaining the optimal reversal trajectory for a given magnetic nano-structure,
+finding a proper field/current pulse is an algebraic problem instead of the
+original nonlinear differential equation.",0712.2101v1
+2007-12-18,Effect of Edge Roughness on Electronic Transport in Graphene Nanoribbon Channel Metal Oxide Semiconductor Field-Effect Transistors,"Results of quantum mechanical simulations of the influence of edge disorder
+on transport in graphene nanoribbon metal oxide semiconductor field-effect
+transistors (MOSFETs) are reported. The addition of edge disorder significantly
+reduces ON-state currents and increases OFF-state currents, and introduces wide
+variability across devices. These effects decrease as ribbon widths increase
+and as edges become smoother. However the bandgap decreases with increasing
+width, thereby increasing the band-to-band tunneling mediated subthreshold
+leakage current even with perfect nanoribbons. These results suggest that
+without atomically precise edge control during fabrication, MOSFET performance
+gains through use of graphene will be difficult to achieve.",0712.3068v1
+2007-12-22,Explicit Non-Adaptive Combinatorial Group Testing Schemes,"Group testing is a long studied problem in combinatorics: A small set of $r$
+ill people should be identified out of the whole ($n$ people) by using only
+queries (tests) of the form ""Does set X contain an ill human?"". In this paper
+we provide an explicit construction of a testing scheme which is better
+(smaller) than any known explicit construction. This scheme has $\bigT{\min[r^2
+\ln n,n]}$ tests which is as many as the best non-explicit schemes have. In our
+construction we use a fact that may have a value by its own right: Linear
+error-correction codes with parameters $[m,k,\delta m]_q$ meeting the
+Gilbert-Varshamov bound may be constructed quite efficiently, in $\bigT{q^km}$
+time.",0712.3876v5
+2007-12-31,"Risk management for analytical methods: conciliating objectives of methods, validation phase and routine decision rules","In the industries that involved either chemistry or biology, such as
+pharmaceutical industries, chemical industries or food industry, the analytical
+methods are the necessary eyes and hear of all the material produced or used.
+If the quality of an analytical method is doubtful, then the whole set of
+decision that will be based on those measures is questionable. For those
+reasons, being able to assess the quality of an analytical method is far more
+than a statistical challenge; it's a matter of ethic and good business
+practices. Many regulatory documents have been releases, primarily ICH and FDA
+documents in the pharmaceutical industry (FDA, 1995, 1997, 2001) to address
+that issue.",0801.0207v1
+2008-01-06,An Efficient Method for Quantum Transport Calculations in Nanostructures using Full Band Structure,"Scaling of semiconductor devices has reached a stage where it has become
+absolutely imperative to consider the quantum mechanical aspects of transport
+in these ultra small devices. In these simulations, often one excludes a
+rigorous band structure treatment, since it poses a huge computational
+challenge. We have proposed here an efficient method for calculating full
+three-dimensionally coupled quantum transport in nanowire transistors including
+full band structure. We have shown the power of the method by simulating hole
+transport in p-type Ge nanowire transistors. The hole band structure obtained
+from our nearest neighbor sp3s* tight binding Hamiltonian agrees well
+qualitatively with more complex and accurate calculations that take third
+nearest neighbors into account. The calculated I-V results show how shifting of
+the energy bands due to confinement can be accurately captured only in a full
+band full quantum simulation.",0801.0880v1
+2008-01-25,New Lower Bounds on Sizes of Permutation Arrays,"A permutation array(or code) of length $n$ and distance $d$, denoted by
+$(n,d)$ PA, is a set of permutations $C$ from some fixed set of $n$ elements
+such that the Hamming distance between distinct members
+$\mathbf{x},\mathbf{y}\in C$ is at least $d$. Let $P(n,d)$ denote the maximum
+size of an $(n,d)$ PA. This correspondence focuses on the lower bound on
+$P(n,d)$. First we give three improvements over the Gilbert-Varshamov lower
+bounds on $P(n,d)$ by applying the graph theorem framework presented by Jiang
+and Vardy. Next we show another two new improved bounds by considering the
+covered balls intersections. Finally some new lower bounds for certain values
+of $n$ and $d$ are given.",0801.3986v1
+2008-01-30,Femtosecond Control of the Magnetization in Ferromagnetic Semiconductors,"We develop a theory of collective spin dynamics triggered by ultrafast
+optical excitation of ferromagnetic semiconductors. Using the density matrix
+equations of motion in the mean field approximation and including magnetic
+anisotropy and hole spin dephasing effects, we predict the development of a
+light--induced magnetization tilt during ultra--short time intervals comparable
+to the pulse duration. This femtosecond dynamics in the coherent temporal
+regime is governed by the interband nonlinear optical polarizations and is
+followed by a second temporal regime governed by the magnetic anisotropy of the
+Fermi sea. We interpret our numerical results by deriving a
+Landau--Gilbert--like equation for the collective spin, which demonstrates an
+ultrafast correction to the magnetic anisotropy effective field due to second
+order coherent nonlinear optical processes. Using the Lindblad semigroup
+method, we also derive a contribution to the interband polarization dephasing
+determined by the Mn spin and the hole spin dephasing. Our predicted
+magnetization tilt and subsequent nonlinear dynamics due to the magnetic
+anisotropy can be controlled by varying the optical pulse intensity, duration,
+and helicity and can be observed with pump--probe magneto--optical
+spectroscopy.",0801.4641v1
+2008-02-01,Vortex Ferroelectric Domains,"We show experimental switching data on microscale capacitors of
+lead-zirconate-titanate (PZT), which reveal time-resolved domain behavior
+during switching on a 100-ns scale. For small circular capacitors, an
+unswitched domain remains in the center while complete switching is observed in
+square capacitors. The observed effect is attributed to the formation of vortex
+domain during polarization switching in circular capacitors. This dynamical
+behavior is modeled using the Landau-Liftshitz-Gilbert equations and found to
+be in detailed agreement with experiment. This simulation implies rotational
+motion of polarization in the xy-plane, a Heisenberg-like result supported by
+the recent model of Naumov and Fu [Phys. Rev. Lett. 98, 077603 (2007)],
+although not directly measurable by the present quasi-static measurements.",0802.0186v1
+2008-02-11,Structure and Optimality of Myopic Policy in Opportunistic Access with Noisy Observations,"A restless multi-armed bandit problem that arises in multichannel
+opportunistic communications is considered, where channels are modeled as
+independent and identical Gilbert-Elliot channels and channel state
+observations are subject to errors. A simple structure of the myopic policy is
+established under a certain condition on the false alarm probability of the
+channel state detector. It is shown that the myopic policy has a semi-universal
+structure that reduces channel selection to a simple round-robin procedure and
+obviates the need to know the underlying Markov transition probabilities. The
+optimality of the myopic policy is proved for the case of two channels and
+conjectured for the general case based on numerical examples.",0802.1379v2
+2008-02-12,"Domain walls in (Ga,Mn)As diluted magnetic semiconductor","We report experimental and theoretical studies of magnetic domain walls in an
+in-plane magnetized (Ga,Mn)As dilute moment ferromagnetic semiconductor. Our
+high-resolution electron holography technique provides direct images of domain
+wall magnetization profiles. The experiments are interpreted based on
+microscopic calculations of the micromagnetic parameters and
+Landau-Lifshitz-Gilbert simulations. We find that the competition of uniaxial
+and biaxial magnetocrystalline anisotropies in the film is directly reflected
+in orientation dependent wall widths, ranging from approximately 40 nm to 120
+nm. The domain walls are of the N\'eel type and evolve from near-$90^{\circ}$
+walls at low-temperatures to large angle [1$\bar{1}$0]-oriented walls and small
+angle [110]-oriented walls at higher temperatures.",0802.1574v1
+2008-02-21,Solving functional reliability issue for an optical electrostatic switch,"In this paper, we report the advantage of using AC actuating signal for
+driving MEMS actuators instead of DC voltages. The study is based upon micro
+mirror devices used in digital mode for optical switching operation. When the
+pull-in effect is used, charge injection occurs when the micro mirror is
+maintained in the deflected position. To avoid this effect, a geometrical
+solution is to realize grounded landing electrodes which are electro-statically
+separated from the control electrodes. Another solution is the use of AC signal
+which eliminates charge injection particularly if a bipolar signal is used.
+Long term experiments have demonstrated the reliability of such a signal
+command to avoid injection of electric charges.",0802.3075v1
+2008-02-21,First principles calculation of spin-interactions and magnetic ground states of Cr trimers on Au(111),"We present calculations of the magnetic ground states of Cr trimers in
+different geometries on top of a Au(111) surface. By using a least square fit
+method based on a fully relativistic embedded-cluster Green's function method
+first we determined the parameters of a classical vector-spin model consisting
+of second and fourth order interactions. The newly developed method requires no
+symmetry constraints, therefore, it is throughout applicable for small
+nanoparticles of arbitrary geometry. The magnetic ground states were then found
+by solving the Landau-Lifshitz-Gilbert equations. In all considered cases the
+configurational energy of the Cr trimers is dominated by large
+antiferromagnetic nearest neighbor interactions, whilst biquadratic
+spin-interactions have the second largest contributions to the energy. We find
+that an equilateral Cr trimer exhibits a frustrated 120$^\circ$ N\'eel type of
+ground state with a small out-of-plane component of the magnetization and we
+show that the Dzyaloshinsky-Moriya interactions determine the chirality of the
+magnetic ground state. In cases of a linear chain and an isosceles trimer
+collinear antiferromagnetic ground states are obtained with a magnetization
+lying parallel to the surface.",0802.3113v1
+2008-04-07,"Energy equilibriation processes of electrons, magnons and phonons on the femtosecond timescale","By means of time-resolved Kerr spectroscopy experiments we relate the energy
+dissipation processes on the femtosecond (electron-spin relaxation time
+$\tau_{el-sp}$) and nanosecond timescale (Gilbert relaxation $\tau_{\alpha}$)
+and compare the results to the first microscopic model, which was proposed by
+Koopmans. For both energy dissipation processes, Elliot-Yafet scattering is
+proposed as the dominant contributor. We controllably manipulate the energy
+dissipation processes by transition metal doping (Pd) and rare earth doping
+(Dy) of a Permalloy film and find that while a change of $\tau_{\alpha}$ of
+more than a factor two is observed, \tau_{el-sp}$ remains constant, contrary to
+the predictions of the model. We explain the discrepancies by relaxation
+channels not considered in the original microscopic model and identify thereby
+the applicability of the model and possible necessary extensions to the model.",0804.0985v1
+2008-04-07,Woven Graph Codes: Asymptotic Performances and Examples,"Constructions of woven graph codes based on constituent block and
+convolutional codes are studied. It is shown that within the random ensemble of
+such codes based on $s$-partite, $s$-uniform hypergraphs, where $s$ depends
+only on the code rate, there exist codes satisfying the Varshamov-Gilbert (VG)
+and the Costello lower bound on the minimum distance and the free distance,
+respectively. A connection between regular bipartite graphs and tailbiting
+codes is shown. Some examples of woven graph codes are presented. Among them an
+example of a rate $R_{\rm wg}=1/3$ woven graph code with $d_{\rm free}=32$
+based on Heawood's bipartite graph and containing $n=7$ constituent rate
+$R^{c}=2/3$ convolutional codes with overall constraint lengths $\nu^{c}=5$ is
+given. An encoding procedure for woven graph codes with complexity proportional
+to the number of constituent codes and their overall constraint length
+$\nu^{c}$ is presented.",0804.0996v2
+2008-05-26,Photometric Follow-up Observations of the Transiting Neptune-Mass Planet GJ 436b,"This paper presents multi-band photometric follow-up observations of the
+Neptune-mass transiting planet GJ 436b, consisting of 5 new ground-based
+transit light curves obtained in May 2007. Together with one already published
+light curve we have at hand a total of 6 light curves, spanning 29 days. The
+analysis of the data yields an orbital period P = 2.64386+-0.00003 days,
+mid-transit time T_c [HJD] =2454235.8355+-0.0001, planet mass M_p = 23.1+-0.9
+M_{\earth} = 0.073+-0.003 M_{Jup}, planet radius R_p = 4.2+-0.2 R_{\earth} =
+0.37+-0.01 R_{Jup} and stellar radius R_s = 0.45+-0.02 R_{\sun}. Our typical
+precision for the mid transit timing for each transit is about 30 seconds. We
+searched the data for a possible signature of a second planet in the system
+through transit timing variations (TTV) and variation of the impact parameter.
+The analysis could not rule out a small, of the order of a minute, TTV and a
+long-term modulation of the impact parameter, of the order of +0.2 year^{-1}.",0805.3915v2
+2008-06-04,"Broadband electrical detection of spin excitations in (Ga,Mn)As using a photovoltage technique","We report on microwave photovoltage and simultaneous magnetotransport
+measurements in a (Ga,Mn)As film oriented normal to the magnetic field. We
+detect the ferromagnetic resonance over a broad frequency range of 2 GHz to
+18.5 GHz and determine the spectroscopic g-factor and separate the Gilbert from
+the inhomogeneous contribution to magnetization relaxation. Temperature
+dependent measurements below the saturation magnetization indicate that the
+photovoltage signal can serve as a sensitive tool to study the crystal
+anisotropy. We demonstrate that the combination of spin dynamics with charge
+transport is a promising tool to study microstructured ferromagnetic
+semiconductor samples.",0806.0785v1
+2008-07-10,Mechanical and Electronic Properties of Ferromagnetic GaMnAs Using Ultrafast Coherent Acoustic Phonons,"Ultrafast two-color pump-probe measurements, involving coherent acoustic
+phonon (CAP) waves, have provided information simultaneously on the mechanical
+properties and on the electronic structure of ferromagnetic GaMnAs. The elastic
+constant C11 of Ga1-xMnxAs (0.03<x<0.07) are observed to be systematically
+smaller than those of GaAs. Both C11 and Vs of GaMnAs are found to increase
+with temperature (78 K<T<295 K), again in contrast to the opposite behavior in
+GaAs. In addition, the fundamental bandgap (at E0 critical point) of Ga1-xMnxAs
+is found to shift slightly to higher energies with Mn concentration.",0807.1740v2
+2008-08-05,A Proof of George Andrews' and Dave Robbins' q-TSPP Conjecture (modulo a finite amount of routine calculations),"In the historic conference Combinatoire Enumerative[LL] wonderfully organized
+by Gilbert Labelle and Pierre Leroux there were many stimulating lectures,
+including a very interesting one by Pierre Leroux himself, who talked about his
+joint work with Xavier Viennot[LV], on solving differential equations
+combinatorially! During the problem session of that very same colloque, chaired
+by Pierre Leroux, Richard Stanley raised some intriguing problems about the
+enumeration of plane partitions, that he later expanded into a fascinating
+article[Sta1]. Most of these problems concerned the enumeration of symmetry
+classes of plane partitions, that were discussed in more detail in another
+article of Stanley[Sta2]. All of the conjectures in the latter article have
+since been proved (see Dave Bressoud's modern classic[B]), except one, that, so
+far, resisted the efforts of the greatest minds in enumerative combinatorics.
+It concerns the proof of an explicit formula for the q-enumeration of totally
+symmetric plane partitions, conjectured independently by George Andrews and
+Dave Robbins([Sta2],[Sta1](conj. 7), [B](conj. 13)). In this tribute to Pierre
+Leroux, we describe how to prove that last stronghold.",0808.0571v2
+2008-08-09,On some deterministic dictionaries supporting sparsity,"We describe a new construction of an incoherent dictionary, referred to as
+the oscillator dictionary, which is based on considerations in the
+representation theory of finite groups. The oscillator dictionary consists of
+order of p^5 unit vectors in a Hilbert space of dimension p, where p is an odd
+prime, whose pairwise inner products have magnitude of at most 4/sqrt(p). An
+explicit algorithm to construct a large portion of the oscillator dictionary is
+presented.",0808.1368v2
+2008-08-13,"Spin Filter, Spin Amplifier and Other Spintronic Applications in Graphene Nanodisks","Graphene nanodisk is a graphene derivative with a closed edge. The trigonal
+zigzag nanodisk with size $N$ has $N$-fold degenerated zero-energy states. A
+nanodisk can be interpletted as a quantum dot with an internal degree of
+freedom. The grand state of nanodisk has been argued to be a quasi-ferromagnet,
+which is a ferromagnetic-like states with a finite but very long life time. We
+investigate the spin-filter effects in the system made of nanodisks and leads
+based on the master equation. The finite-size effect on spin filter is
+intriguing due to a reaction from the polarization of incoming current to a
+quasi-ferromagnet. Analyzing the relaxation process with the use of the
+Landau-Lifshitz-Gilbert equation, we explore the response to four types of
+incoming currents, namely, unpolarized current, perfectly polarized current,
+partially polarized current and pulse polarized current. We propose some
+applications for spintronics, such as spin memory, spin amplifier, spin valve,
+spin-field-effect transistor and spin diode.",0808.1779v1
+2008-08-26,Codes on hypergraphs,"Codes on hypergraphs are an extension of the well-studied family of codes on
+bipartite graphs. Bilu and Hoory (2004) constructed an explicit family of codes
+on regular t-partite hypergraphs whose minimum distance improves earlier
+estimates of the distance of bipartite-graph codes. They also suggested a
+decoding algorithm for such codes and estimated its error-correcting
+capability.
+  In this paper we study two aspects of hypergraph codes. First, we compute the
+weight enumerators of several ensembles of such codes, establishing conditions
+under which they attain the Gilbert-Varshamov bound and deriving estimates of
+their distance. In particular, we show that this bound is attained by codes
+constructed on a fixed bipartite graph with a large spectral gap.
+  We also suggest a new decoding algorithm of hypergraph codes that corrects a
+constant fraction of errors, improving upon the algorithm of Bilu and Hoory.",0808.3453v2
+2008-09-26,Ultra-fast spin dynamics: the effect of colored noise,"Recent experimental results have pushed the limits of magnetization dynamics
+to pico- and femtosecond timescales. This ultra-fast spin dynamics occurs in
+extreme conditions of strong and rapidly varying fields and high temperatures.
+This situation requires new description of magnetization dynamics, even on a
+phenomenological level of the atomistic Landau-Lifshitz-Gilbert equation,
+taking into account that the correlation time for electron system could be of
+the order of the inverse characteristic spin frequency. For this case we
+introduce the thermodynamically correct phenomenological approach for spin
+dynamics based on the Landau-Lifshitz-Miyasaki-Seki equation. The influence of
+the noise correlation time on longitudinal and transverse magnetization
+relaxation is investigated. We also demonstrate the effect of the noise
+correlation time on demagnetisation rate of different materials during
+laser-induced dynamics.",0809.4595v1
+2008-10-08,Magnetic particle hyperthermia: Neel relaxation in magnetic nanoparticles under circularly polarized field,"The mechanism of magnetization reversal in single-domain ferromagnetic
+particles is of interest in many applications, in most of which losses must be
+minimized. In cancer therapy by hyperthermia the opposite requirement prevails:
+the specific loss power should be maximized. Of the mechanisms of dissipation,
+here we study the effect of Neel relaxation on magnetic nanoparticles unable to
+move or rotate and compare the losses in linearly and circularly polarized
+field. We present exact analytical solutions of the Landau-Lifshitz equation as
+derived from the Gilbert equation and use the calculated time-dependent
+magnetizations to find the energy loss per cycle. In frequencies lower than the
+Larmor frequency linear polarization is found to be the better source of heat
+power, at high frequencies (beyond the Larmor frequency) circular polarization
+is preferable.",0810.1455v2
+2008-10-10,SOSEMANUK: a fast software-oriented stream cipher,"Sosemanuk is a new synchronous software-oriented stream cipher, corresponding
+to Profile 1 of the ECRYPT call for stream cipher primitives. Its key length is
+variable between 128 and 256 bits. It ac- commodates a 128-bit initial value.
+Any key length is claimed to achieve 128-bit security. The Sosemanuk cipher
+uses both some basic design principles from the stream cipher SNOW 2.0 and some
+transformations derived from the block cipher SERPENT. Sosemanuk aims at
+improv- ing SNOW 2.0 both from the security and from the efficiency points of
+view. Most notably, it uses a faster IV-setup procedure. It also requires a
+reduced amount of static data, yielding better performance on several
+architectures.",0810.1858v1
+2008-11-14,Trees of cylinders and canonical splittings,"Let T be a tree with an action of a finitely generated group G. Given a
+suitable equivalence relation on the set of edge stabilizers of T (such as
+commensurability, co-elementarity in a relatively hyperbolic group, or
+commutation in a commutative transitive group), we define a tree of cylinders
+T_c. This tree only depends on the deformation space of T; in particular, it is
+invariant under automorphisms of G if T is a JSJ splitting. We thus obtain
+Out(G)-invariant cyclic or abelian JSJ splittings. Furthermore, T_c has very
+strong compatibility properties (two trees are compatible if they have a common
+refinement).",0811.2383v2
+2008-11-21,Numerical Study of Current-Induced Domain-Wall Dynamics: Crossover from Spin Transfer to Momentum Transfer,"We study current-induced dynamics of a magnetic domain wall by solving a
+time-dependent Schr\""{o}dinger equation combined with Landau-Lifshitz-Gilbert
+equation in a one-dimensional electron system coupled to localized spins. Two
+types of domain-wall motions are observed depending on the hard-axis
+anisotropy, $K_{\perp}$, of the localized spin system. For small values of
+$K_{\perp}$, the magnetic domain wall shows a streaming motion driven by spin
+transfer. In contrast, for large values of $K_{\perp}$, a stick-slip motion
+driven by momentum transfer is obtained. We clarify the origin of these
+characters of domain-wall motions in terms of the dynamics of one-particle
+energy levels and distribution functions.",0811.3545v2
+2008-12-02,Application of Conformal Mapping to the determination of Magnetic Moment Distributions in typical Antidot Film Nanostructures,"There has been an increasing technological interest on magnetic thin films
+containing antidot arrays of hexagonal or square symmetry. Part of this
+interest is related to the possibility of domain formation and pinning at the
+antidots boundaries. In this paper, we develop a method for the calculation of
+the magnetic moment distribution for such arrays which concentrates on the
+immediate vicinity of each antidot. For each antidot distribution (square or
+hexagonal) a suitable system of coordinates is defined to exploit the shape of
+the unit-cells of the overall nanostructure. The Landau-Lifshitz-Gilbert-Brown
+equations that govern the distribution of moments are rewritten in terms of
+these coordinates. The equilibrium moments orientation is calculated for each
+position in a Cartesian grid defined for these new coordinate systems, and then
+a conformal transformation is applied to insert the moment vectors into the
+actual unit-cell. The resulting vector maps display quite clearly regions of
+different moment orientation around the antidots, which can be associated with
+nanoscale domains. These results are similar to the ones obtained by other
+authors[1-4] using the NIST oommf method.",0812.0566v1
+2009-01-09,A Better Way to Deal the Cards,"This paper considers the effect of riffle shuffling on decks of cards,
+allowing for some cards to be indistinguishable from other cards. The dual
+problem of dealing a game with hands, such as bridge or poker, is also
+considered. The Gilbert-Shannon-Reeds model of card shuffling is used, along
+with variation distance for measuring how close to uniform a deck has become.
+  The surprising results are that for a deck with only two types of cards (such
+as red and black), the shuffler can greatly improve the randomness of the deck
+by insuring that the top and bottom cards are the same before shuffling. And in
+the case of dealing cards for a game with ""hands"", such as bridge or poker, the
+normal method of dealing cyclically around the table is very far from optimal.
+In the case of a well-shuffled bridge deck, changing to another dealing method
+is as good as doing 3.7 extra shuffles. How the deck is cut in poker affects
+its randomness as well.",0901.1324v4
+2009-03-12,Accuracy thresholds of topological color codes on the hexagonal and square-octagonal lattices,"Accuracy thresholds of quantum error correcting codes, which exploit
+topological properties of systems, defined on two different arrangements of
+qubits are predicted. We study the topological color codes on the hexagonal
+lattice and on the square-octagonal lattice by the use of mapping into the spin
+glass systems. The analysis for the corresponding spin glass systems consists
+of the duality, and the gauge symmetry, which has succeeded in deriving
+locations of special points, which are deeply related with the accuracy
+thresholds of topological error correcting codes. We predict that the accuracy
+thresholds for the topological color codes would be $1-p_c = 0.1096-8 $ for the
+hexagonal lattice and $1-p_c = 0.1092-3$ for the square-octagonal lattice,
+where $1-p$ denotes the error probability on each qubit. Hence both of them are
+expected to be slightly lower than the probability $1-p_c = 0.110028$ for the
+quantum Gilbert-Varshamov bound with a zero encoding rate.",0903.2102v5
+2009-03-12,Designing Optimal Flow Networks,"We investigate the problem of designing a minimum cost flow network
+interconnecting n sources and a single sink, each with known locations and
+flows. The network may contain other unprescribed nodes, known as Steiner
+points. For concave increasing cost functions, a minimum cost network of this
+sort has a tree topology, and hence can be called a Minimum Gilbert
+Arborescence (MGA). We characterise the local topological structure of Steiner
+points in MGAs for linear cost functions. This problem has applications to the
+design of drains, gas pipelines and underground mine access.",0903.2124v1
+2009-04-13,Refined Coding Bounds and Code Constructions for Coherent Network Error Correction,"Coherent network error correction is the error-control problem in network
+coding with the knowledge of the network codes at the source and sink nodes.
+With respect to a given set of local encoding kernels defining a linear network
+code, we obtain refined versions of the Hamming bound, the Singleton bound and
+the Gilbert-Varshamov bound for coherent network error correction. Similar to
+its classical counterpart, this refined Singleton bound is tight for linear
+network codes. The tightness of this refined bound is shown by two construction
+algorithms of linear network codes achieving this bound. These two algorithms
+illustrate different design methods: one makes use of existing network coding
+algorithms for error-free transmission and the other makes use of classical
+error-correcting codes. The implication of the tightness of the refined
+Singleton bound is that the sink nodes with higher maximum flow values can have
+higher error correction capabilities.",0904.1897v2
+2009-04-27,Effect of resistance feedback on spin torque-induced switching of nanomagnets,"In large magnetoresistance devices spin torque-induced changes in resistance
+can produce GHz current and voltage oscillations which can affect magnetization
+reversal. In addition, capacitive shunting in large resistance devices can
+further reduce the current, adversely affecting spin torque switching. Here, we
+simultaneously solve the Landau-Lifshitz-Gilbert equation with spin torque and
+the transmission line telegrapher's equations to study the effects of
+resistance feedback and capacitance on magnetization reversal of both spin
+valves and magnetic tunnel junctions. While for spin valves parallel (P) to
+anti-parallel (AP) switching is adversely affected by the resistance feedback
+due to saturation of the spin torque, in low resistance magnetic tunnel
+junctions P-AP switching is enhanced. We study the effect of resistance
+feedback on the switching time of MTJ's, and show that magnetization switching
+is only affected by capacitive shunting in the pF range.",0904.4159v2
+2009-04-30,A microscopic model for current-induced switching of magnetization for half-metallic leads,"We study the behaviour of the magnetization in a half-metallic
+ferromagnet/nonmagnetic insulator/ferromagnetic metal/paramagnetic metal
+(FM1/NI/FM2/PM) tunnel junction. It is calculated self-consistently within the
+nonequilibrium Keldysh formalism. The magnetic regions are treated as band
+ferromagnets and are described by the single-band Hubbard model. We developed a
+nonequilibrium spectral density approach to solve the Hubbard model
+approximately in the switching magnet. By applying a voltage to the junction it
+is possible to switch between antiparallel (AP) and parallel (P) alignment of
+the magnetizations of the two ferromagnets. The transition from AP to P occurs
+for positive voltages while the inverse transition from P to AP can be induced
+by negative voltages only. This behaviour is in agreement with the Slonczewski
+model of current-induced switching and appears self-consistently within the
+model, i.e. without using half-classical methods like the
+Landau-Lifshitz-Gilbert equation.",0904.4821v1
+2009-05-26,Scattering Theory of Charge-Current Induced Magnetization Dynamics,"In ferromagnets, charge currents can excite magnons via the spin-orbit
+coupling. We develop a novel and general scattering theory of charge current
+induced macrospin magnetization torques in normal metal$|$ferromagnet$|$normal
+metal layers. We apply the formalism to a dirty GaAs$|$(Ga,Mn)As$|$GaAs system.
+By computing the charge current induced magnetization torques and solving the
+Landau-Lifshitz-Gilbert equation, we find magnetization switching for current
+densities as low as $ 5\times 10^{6}$~A/cm$^2$. Our results are in agreement
+with a recent experimental observation of charge-current induced magnetization
+switching in (Ga,Mn)As.",0905.4170v2
+2009-05-28,Riffle shuffles of a deck with repeated cards,"We study the Gilbert-Shannon-Reeds model for riffle shuffles and ask
+  'How many times must a deck of cards be shuffled for the deck to be in close
+to random order?'. In 1992, Bayer and Diaconis gave a solution which gives
+exact and asymptotic results for all decks of practical interest, e.g. a deck
+of 52 cards. But what if one only cares about the colors of the cards or
+disregards the suits focusing solely on the ranks? More generally, how does the
+rate of convergence of a Markov chain change if we are interested in only
+certain features? Our exploration of this problem takes us through random walks
+on groups and their cosets, discovering along the way exact formulas leading to
+interesting combinatorics, an 'amazing matrix', and new analytic methods which
+produce a completely general asymptotic solution that is remarkable accurate.",0905.4698v1
+2009-07-20,Correcting Limited-Magnitude Errors in the Rank-Modulation Scheme,"We study error-correcting codes for permutations under the infinity norm,
+motivated by a novel storage scheme for flash memories call rank modulation. In
+this scheme, a set of $n$ flash cells are combined to create a single virtual
+multi-level cell. Information is stored in the permutation induced by the cell
+charge levels. Spike errors, which are characterized by a limited-magnitude
+change in cell charge levels, correspond to a low-distance change under the
+infinity norm.
+  We define codes protecting against spike errors, called limited-magnitude
+rank-modulation codes (LMRM codes), and present several constructions for these
+codes, some resulting in optimal codes. These codes admit simple recursive, and
+sometimes direct, encoding and decoding procedures.
+  We also provide lower and upper bounds on the maximal size of LMRM codes both
+in the general case, and in the case where the codes form a subgroup of the
+symmetric group. In the asymptotic analysis, the codes we construct out-perform
+the Gilbert-Varshamov-like bound estimate.",0907.3387v2
+2009-07-22,Searching for variable stars in Galactic Open Clusters,"A long-term project, aiming at systematic search for variable stars in
+Galactic Open Clusters, was started at the Geneva Observatory in 2002. We have
+been observing regularly a sample of twenty-seven Galactic Open Clusters in the
+U, B, V Geneva filters. The goal is to identify and to study their variable
+stars, as well as the connection between the variable stars in a cluster and
+the cluster properties. We present the status of this work in progress, and
+show preliminary results for one of these clusters, IC 4651.",0907.3834v1
+2009-07-23,Variability morphologies in the color-magnitude diagram. Searching for secular variability,"This work is part of an effort to detect secular variable objects in large
+scale surveys by analysing their path in color-magnitude diagrams. To this aim,
+we first present the variability morphologies in the V/V-I diagram of several
+types of variable stars. They comprise both periodic and non periodic variable
+stars from the Large Magellanic Cloud, such as classical Cepheids, long period
+variables or Be and R Coronae Borealis stars, as well as two of the detected
+secular variable stars in the Galaxy, FG Sge and V4334 Sgr. The study of the
+different variability morphologies allows the identification of regions in the
+color-magnitude diagram where those secular variable stars could be detected.
+We also estimate the number of such secular variable stars expected in the
+Large Magellanic Cloud.",0907.4090v1
+2009-08-03,Regret Bounds for Opportunistic Channel Access,"We consider the task of opportunistic channel access in a primary system
+composed of independent Gilbert-Elliot channels where the secondary (or
+opportunistic) user does not dispose of a priori information regarding the
+statistical characteristics of the system. It is shown that this problem may be
+cast into the framework of model-based learning in a specific class of
+Partially Observed Markov Decision Processes (POMDPs) for which we introduce an
+algorithm aimed at striking an optimal tradeoff between the exploration (or
+estimation) and exploitation requirements. We provide finite horizon regret
+bounds for this algorithm as well as a numerical evaluation of its performance
+in the single channel model as well as in the case of stochastically identical
+channels.",0908.0319v1
+2009-08-14,Non-Gaussian Scatter in Cluster Scaling Relations,"We investigate the impact of non-Gaussian scatter in the cluster
+mass-observable scaling relation on the mass and redshift distribution of
+clusters detected by wide area surveys. We parameterize non-Gaussian scatter by
+incorporating the third and forth moments (skewness and kurtosis) into the
+distribution P(Mobs|M). We demonstrate that for low scatter mass proxies the
+higher order moments do not significantly affect the observed cluster mass and
+redshift distributions. However, for high scatter mass indicators it is
+necessary for the survey limiting mass threshold to be less than 10^14 h^-1
+Msol to prevent the skewness from having a significant impact on the observed
+number counts, particularly at high redshift. We also show that an unknown
+level of non-Gaussianity in the scatter is equivalent to an additional
+uncertainty on the variance in P(Mobs|M) and thus may limit the constraints
+that can be placed on the dark energy equation of state parameter w.
+Furthermore, positive skewness flattens the mass function at the high mass end,
+and so one must also account for skewness in P(Mobs|M) when using the shape of
+the mass function to constrain cluster scaling-relations.",0908.1978v1
+2009-08-17,A local moment approach to the degenerate Anderson impurity model,"The local moment approach is extended to the orbitally-degenerate [SU(2N)]
+Anderson impurity model (AIM). Single-particle dynamics are obtained over the
+full range of energy scales, focussing here on particle-hole symmetry in the
+strongly correlated regime where the onsite Coulomb interaction leads to
+many-body Kondo physics with entangled spin and orbital degrees of freedom. The
+approach captures many-body broadening of the Hubbard satellites, recovers the
+correct exponential vanishing of the Kondo scale for all N, and its universal
+scaling spectra are found to be in very good agreement with numerical
+renormalization group (NRG) results. In particular the high-frequency
+logarithmic decays of the scaling spectra, obtained here in closed form for
+arbitrary N, coincide essentially perfectly with available numerics from the
+NRG. A particular case of an anisotropic Coulomb interaction, in which the
+model represents a system of N `capacitively-coupled' SU(2) AIMs, is also
+discussed. Here the model is generally characterised by two low-energy scales,
+the crossover between which is seen directly in its dynamics.",0908.2245v1
+2009-10-20,Bifurcation and chaos in spin-valve pillars in a periodic applied magnetic field,"We study the bifurcation and chaos scenario of the macro-magnetization vector
+in a homogeneous nanoscale-ferromagnetic thin film of the type used in
+spin-valve pillars. The underlying dynamics is described by a generalized
+Landau-Lifshitz-Gilbert (LLG) equation. The LLG equation has an especially
+appealing form under a complex stereographic projection, wherein the
+qualitative equivalence of an applied field and a spin-current induced torque
+is transparent. Recently chaotic behavior of such a spin vector has been
+identified by Zhang and Li using a spin polarized current passing through the
+pillar of constant polarization direction and periodically varying magnitude,
+owing to the spin-transfer torque effect. In this paper we show that the same
+dynamical behavior can be achieved using a periodically varying applied
+magnetic field, in the presence of a constant DC magnetic field and constant
+spin current, which is technically much more feasible, and demonstrate
+numerically the chaotic dynamics in the system for an infinitely thin film.
+Further, it is noted that in the presence of a nonzero crystal anisotropy field
+chaotic dynamics occurs at much lower magnitudes of the spin-current and DC
+applied field.",0910.3776v1
+2009-12-08,Evidence of superconductivity on the border of quasi-2D ferromagnetism in Ca2RuO4 at high pressure,"The layered perovskite Ca2RuO4 is a spin-one Mott insulator at ambient
+pressure and exhibits metallic ferromagnetism at least up to ~ 80 kbar with a
+maximum Curie temperature of 28 K. Above ~ 90 kbar and up to 140 kbar, the
+highest pressure reached, the resistivity and ac susceptibility show pronounced
+downturns below ~ 0.4 K in applied magnetic fields of up to ~10 mT. This
+indicates that our specimens of Ca2RuO4 are weakly superconducting on the
+border of a quasi-2D ferromagnetic state.",0912.1513v1
+2010-02-24,"JSJ decompositions: definitions, existence, uniqueness. II. Compatibility and acylindricity","This paper and its companion arXiv:0911.3173 have been replaced by
+arXiv:1602.05139.
+  We define the compatibility JSJ tree of a group G over a class of subgroups.
+It exists whenever G is finitely presented and leads to a canonical tree (not a
+deformation space) which is invariant under automorphisms. Under acylindricity
+hypotheses, we prove that the (usual) JSJ deformation space and the
+compatibility JSJ tree exist, and we describe their flexible subgroups. We
+apply these results to finitely generated CSA groups, \Gamma-limit groups
+(allowing torsion), and relatively hyperbolic groups.",1002.4564v3
+2010-03-05,Magnetoresistance in nanostructures: the role of nonuniform current,"We developed a method to calculate the magnetoresistance of magnetic
+nanostructures. We discretize a magnetic disk in small cells and numerically
+solve the Landau-Lifshitz-Gilbert (LLG) equation in order to obtain its
+magnetization profile. We consider a anisotropic magnetoresistance (AMR) that
+depends on the local magnetization as the main source of the magnetoresistance.
+We then use it as an input to calculate the resistance and current distribution
+numerically, using a relaxation method. We show how magnetoresistance
+measurements can be useful to obtain information on the magnetic structure.
+Additionally, we obtain non-homogeneous current distributions for different
+magnetic configurations in static and dynamical regimes.",1003.1323v2
+2010-03-21,Current-induced domain wall motion with adiabatic spin torque only in cylindrical nanowires,"We investigate current-driven domain wall (DW) propagation in magnetic
+nanowires in the framework of the modified Landau-Lifshitz-Gilbert equation
+with both adiabatic and nonadiabatic spin torque (NAST) terms. Contrary to the
+common opinion that NAST is indispensable for DW motion[1,2], we point out that
+adiabatic spin torque (AST) only is enough for current-driven DW motion in a
+cylindrical (uniaxial) nanowire. Apart from a discussion of the rigid DW motion
+from the energy and angular momentum viewpoint, we also propose an experimental
+scheme to measure the spin current polarization by combining both field and
+current driven DW motion in a flat (biaxial) wire.",1003.3976v1
+2010-04-01,Multipliers of locally compact quantum groups via Hilbert C$^*$-modules,"A result of Gilbert shows that every completely bounded multiplier $f$ of the
+Fourier algebra $A(G)$ arises from a pair of bounded continuous maps
+$\alpha,\beta:G \rightarrow K$, where $K$ is a Hilbert space, and $f(s^{-1}t) =
+(\beta(t)|\alpha(s))$ for all $s,t\in G$. We recast this in terms of
+adjointable operators acting between certain Hilbert C$^*$-modules, and show
+that an analogous construction works for completely bounded left multipliers of
+a locally compact quantum group. We find various ways to deal with right
+multipliers: one of these involves looking at the opposite quantum group, and
+this leads to a proof that the (unbounded) antipode acts on the space of
+completely bounded multipliers, in a way which interacts naturally with our
+representation result. The dual of the universal quantum group (in the sense of
+Kustermans) can be identified with a subalgebra of the completely bounded
+multipliers, and we show how this fits into our framework. Finally, this
+motivates a certain way to deal with two-sided multipliers.",1004.0215v3
+2010-04-22,Optimal time-dependent polarized current pattern for fast domain wall propagation in nanowires: Exact solutions for biaxial and uniaxial anisotropies,"One of the important issues in nanomagnetism is to lower the current needed
+for a technologically useful domain wall (DW) propagation speed. Based on the
+modified Landau-Lifshitz-Gilbert (LLG) equation with both Slonczewski
+spin-transfer torque and the field-like torque, we derive the optimal spin
+current pattern for fast DW propagation along nanowires. Under such conditions,
+the DW velocity in biaxial wires can be enhanced as much as ten times compared
+to the velocities achieved in experiments so far. Moreover, the fast variation
+of spin polarization can help DW depinning. Possible experimental realizations
+are discussed.",1004.3840v1
+2010-05-03,Criticality of an isotropic-to-smectic transition induced by anisotropic quenched disorder,"We report combined optical birefringence and neutron scattering measurements
+on the liquid crystal 12CB nanoconfined in mesoporous silicon layers. This
+liquid crystal exhibits strong nematic-smectic coupling responsible for a
+discontinuous isotropic-to-smectic phase transition in the bulk state. Confined
+in porous silicon, 12CB is subjected to strong anisotropic quenched disorder: a
+short-ranged smectic state evolves out of a paranematic phase. This
+transformation appears continuous, losing its bulk first order character. This
+contrasts with previously reported observations on liquid crystals under
+isotropic quenched disorder. In the low temperature phase, both orientational
+and translational order parameters obey the same power-law.",1005.0240v1
+2010-05-21,A Study on Potential of Integrating Multimodal Interaction into Musical Conducting Education,"With the rapid development of computer technology, computer music has begun
+to appear in the laboratory. Many potential utility of computer music is
+gradually increasing. The purpose of this paper is attempted to analyze the
+possibility of integrating multimodal interaction such as vision-based hand
+gesture and speech interaction into musical conducting education. To achieve
+this purpose, this paper is focus on discuss some related research and the
+traditional musical conducting education. To do so, six musical conductors had
+been interviewed to share their musical conducting learning/ teaching
+experience. These interviews had been analyzed in this paper to show the
+syllabus and the focus of musical conducting education for beginners.",1005.4014v1
+2010-05-28,Dissipative structures in a nonlinear dynamo,"This paper considers magnetic field generation by a fluid flow in a system
+referred to as the Archontis dynamo: a steady nonlinear magnetohydrodynamic
+(MHD) state is driven by a prescribed body force. The field and flow become
+almost equal and dissipation is concentrated in cigar-like structures centred
+on straight-line separatrices. Numerical scaling laws for energy and
+dissipation are given that extend previous calculations to smaller
+diffusivities. The symmetries of the dynamo are set out, together with their
+implications for the structure of field and flow along the separatrices. The
+scaling of the cigar-like dissipative regions, as the square root of the
+diffusivities, is explained by approximations near the separatrices. Rigorous
+results on the existence and smoothness of solutions to the steady, forced MHD
+equations are given.",1005.5259v2
+2010-06-11,Spherical single-roll dynamos at large magnetic Reynolds numbers,"This paper concerns kinematic helical dynamos in a spherical fluid body
+surrounded by an insulator. In particular, we examine their behaviour in the
+regime of large magnetic Reynolds number $\Rm$, for which dynamo action is
+usually concentrated upon a simple resonant stream-surface. The dynamo
+eigensolutions are computed numerically for two representative single-roll
+flows using a compact spherical harmonic decomposition and fourth-order
+finite-differences in radius. These solutions are then compared with the growth
+rates and eigenfunctions of the Gilbert and Ponty (2000) large $\Rm$ asymptotic
+theory. We find good agreement between the growth rates when $\Rm>10^4$, and
+between the eigenfunctions when $\Rm>10^5$.",1006.2308v2
+2010-06-11,On the Queueing Behavior of Random Codes over a Gilbert-Elliot Erasure Channel,"This paper considers the queueing performance of a system that transmits
+coded data over a time-varying erasure channel. In our model, the queue length
+and channel state together form a Markov chain that depends on the system
+parameters. This gives a framework that allows a rigorous analysis of the queue
+as a function of the code rate. Most prior work in this area either ignores
+block-length (e.g., fluid models) or assumes error-free communication using
+finite codes. This work enables one to determine when such assumptions provide
+good, or bad, approximations of true behavior. Moreover, it offers a new
+approach to optimize parameters and evaluate performance. This can be valuable
+for delay-sensitive systems that employ short block lengths.",1006.2403v1
+2010-06-16,Storing Small Photonic Cluster States in a Dephasing Environment,"We consider the effects of decoherence on the entanglement of photonic
+cluster states. Large photonic cluster states can be built by fusing together
+smaller photonic cluster states via probabilistic fusion operations. For this
+construction process it is necessary to store these smaller cluster states in
+some way so as to have them available for attempted fusion operations. While in
+storage the photonic cluster states may undergo dephasing. The effects of
+dephasing on small, primitive cluster states is explored here with the aim of
+determining how to locally rotate the qubits of the cluster state so as to lose
+the least amount of entanglement due to the dephasing process.",1006.3192v1
+2010-08-05,Subsystem codes with spatially local generators,"We study subsystem codes whose gauge group has local generators in the 2D
+geometry. It is shown that there exists a family of such codes defined on
+lattices of size LxL with the number of logical qubits k and the minimum
+distance d both proportional to L. The gauge group of these codes involves only
+two-qubit generators of type XX and ZZ coupling nearest neighbor qubits (and
+some auxiliary one-qubit generators). Our proof is not constructive as it
+relies on a certain version of the Gilbert-Varshamov bound for classical codes.
+Along the way we introduce and study properties of generalized Bacon-Shor codes
+which might be of independent interest. Secondly, we prove that any 2D
+subsystem [n,k,d] code with spatially local generators obeys upper bounds
+kd=O(n) and d^2=O(n). The analogous upper bound proved recently for 2D
+stabilizer codes is kd^2=O(n). Our results thus demonstrate that subsystem
+codes can be more powerful than stabilizer codes under the spatial locality
+constraint.",1008.1029v1
+2010-08-14,Escape of resources in distributed clustering processes,"In a distributed clustering algorithm introduced by Coffman, Courtois,
+Gilbert and Piret \cite{coffman91}, each vertex of $\mathbb{Z}^d$ receives an
+initial amount of a resource, and, at each iteration, transfers all of its
+resource to the neighboring vertex which currently holds the maximum amount of
+resource. In \cite{hlrnss} it was shown that, if the distribution of the
+initial quantities of resource is invariant under lattice translations, then
+the flow of resource at each vertex eventually stops almost surely, thus
+solving a problem posed in \cite{berg91}. In this article we prove the
+existence of translation-invariant initial distributions for which resources
+nevertheless escape to infinity, in the sense that the the final amount of
+resource at a given vertex is strictly smaller in expectation than the initial
+amount. This answers a question posed in \cite{hlrnss}.",1008.2426v1
+2010-08-25,The self-avoiding walk in a strip,"We review the existence of the infinite length self-avoiding walk in the half
+plane and its relationship to bridges. We prove that this probability measure
+is also given by the limit as $\beta \rightarrow \beta_c-$ of the probability
+measure on all finite length walks $\omega$ with the probability of $\omega$
+proportional to $\beta_c^{|\omega|}$ where $|\omega|$ is the number of steps in
+$\omega$. The self-avoiding walk in a strip $\{z : 0<\Im(z)<y\}$ is defined by
+considering all self-avoiding walks $\omega$ in the strip which start at the
+origin and end somewhere on the top boundary with probability proportional to
+$\beta_c^{|\omega|}$ We prove that this probability measure may be obtained by
+conditioning the SAW in the half plane to have a bridge at height $y$. This
+observation is the basis for simulations to test conjectures on the
+distribution of the endpoint of the SAW in a strip and the relationship between
+the distribution of this strip SAW and SLE$_{8/3}$.",1008.4321v2
+2010-08-29,Chirality control via double vortices in asymmetric Co dots,"Reproducible control of the magnetic vortex state in nanomagnets is of
+critical importance. We report on chirality control by manipulating the size
+and/or thickness of asymmetric Co dots. Below a critical diameter and/or
+thickness, chirality control is achieved by the nucleation of single vortex.
+Interestingly, above these critical dimensions chirality control is realized by
+the nucleation and subsequent coalescence of two vortices, resulting in a
+single vortex with the opposite chirality as found in smaller dots.
+Micromagnetic simulations and magnetic force microscopy highlight the role of
+edge-bound halfvortices in facilitating the coalescence process.",1008.4963v2
+2010-09-18,Composite excitation of Josephson phase and spin waves in Josephson junctions with ferromagnetic insulator,"Coupling of Josephson-phase and spin-waves is theoretically studied in a
+superconductor/ferromagnetic insulator/superconductor (S/FI/S) junction.
+Electromagnetic (EM) field inside the junction and the Josephson current
+coupled with spin-waves in FI are calculated by combining Maxwell and
+Landau-Lifshitz-Gilbert equations. In the S/FI/S junction, it is found that the
+current-voltage (I-V) characteristic shows two resonant peaks. Voltages at the
+resonant peaks are obtained as a function of the normal modes of EM field,
+which indicates a composite excitation of the EM field and spin-waves in the
+S/FI/S junction. We also examine another type of junction, in which a
+nonmagnetic insulator (I) is located at one of interfaces between S and FI. In
+such a S/I/FI/S junction, three resonant peaks appear in the I-V curve, since
+the Josephson-phase couples to the EM field in the I layer.",1009.3551v3
+2010-09-21,On the Flow-Level Delay of a Spatial Multiplexing MIMO Wireless Channel,"The MIMO wireless channel offers a rich ground for quality of service
+analysis. In this work, we present a stochastic network calculus analysis of a
+MIMO system, operating in spatial multiplexing mode, using moment generating
+functions (MGF). We quantify the spatial multiplexing gain, achieved through
+multiple antennas, for flow level quality of service (QoS) performance.
+Specifically we use Gilbert-Elliot model to describe individual spatial paths
+between the antenna pairs and model the whole channel by an N-State Markov
+Chain, where N depends upon the degrees of freedom available in the MIMO
+system. We derive probabilistic delay bounds for the system and show the impact
+of increasing the number of antennas on the delay bounds under various
+conditions, such as channel burstiness, signal strength and fading speed.
+Further we present results for multi-hop scenarios under statistical
+independence.",1009.4091v1
+2010-09-22,Optimal control of magnetization dynamics in ferromagnetic heterostructures by spin--polarized currents,"We study the switching-process of the magnetization in a
+ferromagnetic-normal-metal multilayer system by a spin polarized electrical
+current via the spin transfer torque. We use a spin drift-diffusion equation
+(SDDE) and the Landau-Lifshitz-Gilbert equation (LLGE) to capture the coupled
+dynamics of the spin density and the magnetization dynamic of the
+heterostructure. Deriving a fully analytic solution of the stationary SDDE we
+obtain an accurate, robust, and fast self-consistent model for the
+spin-distribution and spin transfer torque inside general ferromagnetic/normal
+metal heterostructures. Using optimal control theory we explore the switching
+and back-switching process of the analyzer magnetization in a seven-layer
+system. Starting from a Gaussian, we identify a unified current pulse profile
+which accomplishes both processes within a specified switching time.",1009.4296v2
+2010-09-29,Acoustically driven ferromagnetic resonance,"Surface acoustic waves (SAW) in the GHz frequency range are exploited for the
+all-elastic excitation and detection of ferromagnetic resonance (FMR) in a
+ferromagnetic/ferroelectric (nickel/lithium niobate) hybrid device. We measure
+the SAW magneto-transmission at room temperature as a function of frequency,
+external magnetic field magnitude, and orientation. Our data are well described
+by a modified Landau-Lifshitz-Gilbert approach, in which a virtual,
+strain-induced tickle field drives the magnetization precession. This causes a
+distinct magnetic field orientation dependence of elastically driven FMR that
+we observe in both model and experiment.",1009.5798v2
+2010-10-05,Effects of Strong Gravitational Lensing on Millimeter-Wave Galaxy Number Counts,"We study the effects of strong lensing on the observed number counts of mm
+sources using a ray tracing simulation and two number count models of unlensed
+sources. We employ a quantitative treatment of maximum attainable magnification
+factor depending on the physical size of the sources, also accounting for
+effects of lens halo ellipticity. We calculate predicted number counts and
+redshift distributions of mm galaxies including the effects of strong lensing
+and compare with the recent source count measurements of the South Pole
+Telescope (SPT). The predictions have large uncertainties, especially the
+details of the mass distribution in lens galaxies and the finite extent of
+sources, but the SPT observations are in good agreement with predictions. The
+sources detected by SPT are predicted to largely consist of strongly lensed
+galaxies at z>2. The typical magnifications of these sources strongly depends
+on both the assumed unlensed source counts and the flux of the observed
+sources.",1010.0998v2
+2010-10-15,The Significance of Non-ergodicity Property of Statistical Mechanics Systems for Understanding Resting State of a Living Cell,"A better grasp of the physical foundations of life is necessary before we can
+understand the processes occurring inside a living cell. In his physical theory
+of the cell, American physiologist Gilbert Ling introduced an important notion
+of the resting state of the cell. He describes this state as an independent
+stable thermodynamic state of a living substance in which it has stored all the
+energy it needs to perform all kinds of biological work. This state is
+characterised by lower entropy of the system than in an active state. However,
+Ling's approach is primarily qualitative in terms of thermodynamics and it
+needs to be characterised more specifically. To this end, we propose a new
+thermodynamic approach to studying Ling's model of the living cell (Ling's
+cell), the center piece of which is the non-ergodicity property which has
+recently been proved for a wide range of systems in statistical mechanics [7].
+These approach allowed us to develop general thermodynamic approaches to
+explaining some of the well-known physiological phenomena, which can be used
+for further physical analysis of these phenomena using specific physical
+models.",1010.3226v1
+2010-11-29,Superoperator Analysis of Entanglement in a Four-Qubit Cluster State,"In this paper we utilize superoperator formalism to explore the entanglement
+evolution of four-qubit cluster states in a number of decohering environments.
+A four-qubit cluster state is a resource for the performance of an arbitrary
+single logical qubit rotation via measurement based cluster state quantum
+computation. We are specifically interested in the relationship between
+entanglement evolution and the fidelity with which the arbitrary single logical
+qubit rotation can be implemented in the presence of decoherence as this will
+have important experimental ramifications. We also note the exhibition of
+entanglement sudden death (ESD) and ask how severely its onset affects the
+utilization of the cluster state as a means of implementing an arbitrary single
+logical qubit rotation.",1011.6336v2
+2011-02-14,Computing the Ball Size of Frequency Permutations under Chebyshev Distance,"Let $S_n^\lambda$ be the set of all permutations over the multiset
+$\{\overbrace{1,...,1}^{\lambda},...,\overbrace{m,...,m}^\lambda\}$ where
+$n=m\lambda$. A frequency permutation array (FPA) of minimum distance $d$ is a
+subset of $S_n^\lambda$ in which every two elements have distance at least $d$.
+FPAs have many applications related to error correcting codes. In coding
+theory, the Gilbert-Varshamov bound and the sphere-packing bound are derived
+from the size of balls of certain radii. We propose two efficient algorithms
+that compute the ball size of frequency permutations under Chebyshev distance.
+Both methods extend previous known results. The first one runs in $O({2d\lambda
+\choose d\lambda}^{2.376}\log n)$ time and $O({2d\lambda \choose
+d\lambda}^{2})$ space. The second one runs in $O({2d\lambda \choose
+d\lambda}{d\lambda+\lambda\choose \lambda}\frac{n}{\lambda})$ time and
+$O({2d\lambda \choose d\lambda})$ space. For small constants $\lambda$ and $d$,
+both are efficient in time and use constant storage space.",1102.2799v2
+2011-02-25,Modeling Extragalactic Foregrounds and Secondaries for Unbiased Estimation of Cosmological Parameters From Primary CMB Anisotropy,"Using the latest physical modeling and constrained by the most recent data,
+we develop a phenomenological parameterized model of the contributions to
+intensity and polarization maps at millimeter wavelengths from external
+galaxies and Sunyaev-Zeldovich effects. We find such modeling to be necessary
+for estimation of cosmological parameters from Planck data. For example,
+ignoring the clustering of the infrared background would result in a bias in
+n_s of 7 sigma. We show that the simultaneous marginalization over a full
+foreground model can eliminate such biases, while increasing the statistical
+uncertainty in cosmological parameters by less than 20%. The small increases in
+uncertainty can be significantly reduced with the inclusion of
+higher-resolution ground-based data.
+  The multi-frequency analysis we employ involves modeling 46 total power
+spectra and marginalization over 17 foreground parameters. We show that we can
+also reduce the data to a best estimate of the CMB power spectra, and just two
+principal components (with constrained amplitudes) describing residual
+foreground contamination.",1102.5195v1
+2011-03-02,Switching dynamics of a magnetostrictive single-domain nanomagnet subjected to stress,"The temporal evolution of the magnetization vector of a single-domain
+magnetostrictive nanomagnet, subjected to in-plane stress, is studied by
+solving the Landau-Lifshitz-Gilbert equation. The stress is ramped up linearly
+in time and the switching delay, which is the time it takes for the
+magnetization to flip, is computed as a function of the ramp rate. For high
+levels of stress, the delay exhibits a non-monotonic dependence on the ramp
+rate, indicating that there is an {\it optimum} ramp rate to achieve the
+shortest delay. For constant ramp rate, the delay initially decreases with
+increasing stress but then saturates showing that the trade-off between the
+delay and the stress (or the energy dissipated in switching) becomes less and
+less favorable with increasing stress. All of these features are due to a
+complex interplay between the in-plane and out-of-plane dynamics of the
+magnetization vector induced by stress.",1103.0352v1
+2011-03-21,Delay Constrained Throughput Analysis of a Correlated MIMO Wireless Channel,"The maximum traffic arrival rate at the network for a given delay guarantee
+(delay constrained throughput) has been well studied for wired channels.
+However, few results are available for wireless channels, especially when
+multiple antennas are employed at the transmitter and receiver. In this work,
+we analyze the network delay constrained throughput of a multiple input
+multiple output (MIMO) wireless channel with time-varying spatial correlation.
+The MIMO channel is modeled via its virtual representation, where the
+individual spatial paths between the antenna pairs are Gilbert-Elliot channels.
+The whole system is then described by a K-State Markov chain, where K depends
+upon the degree of freedom (DOF) of the channel. We prove that the DOF based
+modeling is indeed accurate. Furthermore, we study the impact of the delay
+requirements at the network layer, violation probability and the number of
+antennas on the throughput under different fading speeds and signal strength.",1103.4016v1
+2011-03-29,Current induced rotational torques in the skyrmion lattice phase of chiral magnets,"In chiral magnets without inversion symmetry, the magnetic structure can form
+a lattice of magnetic whirl lines, a two-dimensional skyrmion lattice,
+stabilized by spin-orbit interactions in a small range of temperatures and
+magnetic fields. The twist of the magnetization within this phase gives rise to
+an efficient coupling of macroscopic magnetic domains to spin currents. We
+analyze the resulting spin-transfer effects, and, in particular, focus on the
+current induced rotation of the magnetic texture by an angle. Such a rotation
+can arise from macroscopic temperature gradients in the system as has recently
+been shown experimentally and theoretically. Here we investigate an alternative
+mechanism, where small distortions of the skyrmion lattice and the transfer of
+angular momentum to the underlying atomic lattice play the key role. We employ
+the Landau-Lifshitz-Gilbert equation and adapt the Thiele method to derive an
+effective equation of motion for the rotational degree of freedom. We discuss
+the dependence of the rotation angle on the orientation of the applied magnetic
+field and the distance to the phase transition.",1103.5548v2
+2011-04-07,Finite-size effects on the magnetoelectric response of field-driven ferroelectric/ferromagnetic chains,"We study theoretically the coupled multiferroic dynamics of one-dimensional
+ferroelectric/ferromagnet chains driven by harmonic magnetic and electric
+fields as a function of the chain length. A linear magnetoelectric coupling is
+dominated by the spin-polarized screening charge at the interface. We performed
+Monte-Carlo simulations and calculations based on the coupled
+Landau-Lifshitz-Gilbert and Landau-Khalatnikov equations showing that the net
+magnetization and the total polarization of thin heterostructures, i.e. with up
+to ten ferroelectric and ferromagnetic sites counted from the interface, can be
+completely reversed by external electric and magnetic fields, respectively.
+However, for larger system solely a certain magnetoelectrical control can be
+achieved.",1104.1269v3
+2011-04-12,The Effect of Disorder in Superfluid Double Layer Graphene,"We investigate the superfluid properties of disordered double layer graphene
+systems using the non-equilibrium Green's function (NEGF) formalism. The
+complexity of such a structure makes it imperative to study the effects of
+lattice vacancies which will inevitably arise during fabrication. We present
+and compare room temperature performance characteristics for both ideal and
+disordered bilayer graphene systems in an effort to illustrate the behavior of
+a Bose-Einstein Condensate in the presence of lattice defects under
+non-equilibrium conditions. We find that lattice vacancies spread throughout
+the top layer past the coherence length have a reduced effect compared to the
+ideal case. However, vacancies concentrated near the metal contacts within the
+coherence length significantly alter the interlayer superfluid transport
+properties.",1104.2343v1
+2011-05-12,"Incremental Cycle Detection, Topological Ordering, and Strong Component Maintenance","We present two on-line algorithms for maintaining a topological order of a
+directed $n$-vertex acyclic graph as arcs are added, and detecting a cycle when
+one is created. Our first algorithm handles $m$ arc additions in $O(m^{3/2})$
+time. For sparse graphs ($m/n = O(1)$), this bound improves the best previous
+bound by a logarithmic factor, and is tight to within a constant factor among
+algorithms satisfying a natural {\em locality} property. Our second algorithm
+handles an arbitrary sequence of arc additions in $O(n^{5/2})$ time. For
+sufficiently dense graphs, this bound improves the best previous bound by a
+polynomial factor. Our bound may be far from tight: we show that the algorithm
+can take $\Omega(n^2 2^{\sqrt{2\lg n}})$ time by relating its performance to a
+generalization of the $k$-levels problem of combinatorial geometry. A
+completely different algorithm running in $\Theta(n^2 \log n)$ time was given
+recently by Bender, Fineman, and Gilbert. We extend both of our algorithms to
+the maintenance of strong components, without affecting the asymptotic time
+bounds.",1105.2397v1
+2011-05-30,Orthogonal Matching Pursuit: A Brownian Motion Analysis,"A well-known analysis of Tropp and Gilbert shows that orthogonal matching
+pursuit (OMP) can recover a k-sparse n-dimensional real vector from 4 k log(n)
+noise-free linear measurements obtained through a random Gaussian measurement
+matrix with a probability that approaches one as n approaches infinity. This
+work strengthens this result by showing that a lower number of measurements, 2
+k log(n - k), is in fact sufficient for asymptotic recovery. More generally,
+when the sparsity level satisfies kmin <= k <= kmax but is unknown, 2 kmax
+log(n - kmin) measurements is sufficient. Furthermore, this number of
+measurements is also sufficient for detection of the sparsity pattern (support)
+of the vector with measurement errors provided the signal-to-noise ratio (SNR)
+scales to infinity. The scaling 2 k log(n - k) exactly matches the number of
+measurements required by the more complex lasso method for signal recovery with
+a similar SNR scaling.",1105.5853v1
+2011-06-07,Magneto-optical Kerr Effect Studies of Square Artificial Spin Ice,"We report a magneto-optical Kerr effect study of the collective magnetic
+response of artificial square spin ice, a lithographically-defined array of
+single-domain ferromagnetic islands. We find that the anisotropic inter-island
+interactions lead to a non-monotonic angular dependence of the array coercive
+field. Comparisons with micromagnetic simulations indicate that the two
+perpendicular sublattices exhibit distinct responses to island edge roughness,
+which clearly influence the magnetization reversal process. Furthermore, such
+comparisons demonstrate that disorder associated with roughness in the island
+edges plays a hitherto unrecognized but essential role in the collective
+behavior of these systems.",1106.1394v2
+2011-06-15,Dissipative hydrodynamic equation of a ferromagnetic Bose-Einstein condensate: Analogy to magnetization dynamics in conducting ferromagnets,"The hydrodynamic equation of a spinor Bose-Einstein condensate (BEC) gives a
+simple description of spin dynamics in the condensate. We introduce the
+hydrodynamic equation of a ferromagnetic BEC with dissipation originating from
+the energy dissipation of the condensate. The dissipative hydrodynamic equation
+has the same form as an extended Landau-Lifshitz-Gilbert (LLG) equation, which
+describes the magnetization dynamics of ferromagnets interacting with
+spin-polarized currents. Employing the dissipative hydrodynamic equation, we
+demonstrate the magnetic domain pattern dynamics of a ferromagnetic BEC in the
+presence and absence of a current of particles, and discuss the effects of the
+current on domain pattern formation. We also discuss the characteristic lengths
+of domain patterns that have domain walls with and without finite
+magnetization.",1106.2876v4
+2011-07-02,Energy dissipation and switching delay in spin-transfer torque switching of nanomagnets with low-saturation magnetization in the presence of thermal fluctuations,"A common ploy to reduce the switching current and energy dissipation in
+spin-transfer-torque driven magnetization switching of shape-anisotropic
+single-domain nanomagnets is to employ magnets with low saturation
+magnetization $M_s$ and high shape-anisotropy. The high shape-anisotropy
+compensates for low $M_s$ to keep the static switching error rate constant.
+However, this ploy increases the switching delay, its variance in the presence
+of thermal noise, and the dynamic switching error rate. Using the stochastic
+Landau-Lifshitz-Gilbert equation with a random torque emulating thermal noise,
+we show that pumping some excess spin-polarized current into the nanomagnet
+during switching will keep the mean switching delay and its variance constant
+as we reduce $M_s$, while still reducing the energy dissipation significantly.",1107.0387v2
+2011-08-01,Noise Sensitivity in Continuum Percolation,"We prove that the Poisson Boolean model, also known as the Gilbert disc
+model, is noise sensitive at criticality. This is the first such result for a
+Continuum Percolation model, and the first for which the critical probability
+p_c \ne 1/2. Our proof uses a version of the Benjamini-Kalai-Schramm Theorem
+for biased product measures. A quantitative version of this result was recently
+proved by Keller and Kindler. We give a simple deduction of the
+non-quantitative result from the unbiased version. We also develop a quite
+general method of approximating Continuum Percolation models by discrete models
+with p_c bounded away from zero; this method is based on an extremal result on
+non-uniform hypergraphs.",1108.0310v2
+2011-08-23,Vortex Lines in Topological Insulator-Superconductor Heterostructures,"3D topological insulator/s-wave superconductor heterostructures have been
+predicted as candidate systems for the observation of Majorana fermions in the
+presence of superconducting vortices. In these systems, Majorana fermions are
+expected to form at the interface between the topological insulator and the
+superconductor while the bulk plays no role. Yet the bulk of a 3D topological
+insulator penetrated by a magnetic flux is not inert and can gap the surface
+vortex modes destroying their Majorana nature. In this work, we demonstrate the
+circumstances under which only the surface physics is important and when the
+bulk physics plays an important role in the location and energy of the Majorana
+modes.",1108.4711v1
+2011-08-28,Low-complexity quantum codes designed via codeword-stabilized framework,"We consider design of the quantum stabilizer codes via a two-step,
+low-complexity approach based on the framework of codeword-stabilized (CWS)
+codes. In this framework, each quantum CWS code can be specified by a graph and
+a binary code. For codes that can be obtained from a given graph, we give
+several upper bounds on the distance of a generic (additive or non-additive)
+CWS code, and the lower Gilbert-Varshamov bound for the existence of additive
+CWS codes. We also consider additive cyclic CWS codes and show that these codes
+correspond to a previously unexplored class of single-generator cyclic
+stabilizer codes. We present several families of simple stabilizer codes with
+relatively good parameters.",1108.5490v1
+2011-09-16,Parallel Sparse Matrix-Matrix Multiplication and Indexing: Implementation and Experiments,"Generalized sparse matrix-matrix multiplication (or SpGEMM) is a key
+primitive for many high performance graph algorithms as well as for some linear
+solvers, such as algebraic multigrid. Here we show that SpGEMM also yields
+efficient algorithms for general sparse-matrix indexing in distributed memory,
+provided that the underlying SpGEMM implementation is sufficiently flexible and
+scalable. We demonstrate that our parallel SpGEMM methods, which use
+two-dimensional block data distributions with serial hypersparse kernels, are
+indeed highly flexible, scalable, and memory-efficient in the general case.
+This algorithm is the first to yield increasing speedup on an unbounded number
+of processors; our experiments show scaling up to thousands of processors in a
+variety of test scenarios.",1109.3739v2
+2011-10-06,A new class of codes for Boolean masking of cryptographic computations,"We introduce a new class of rate one-half binary codes: {\bf complementary
+information set codes.} A binary linear code of length $2n$ and dimension $n$
+is called a complementary information set code (CIS code for short) if it has
+two disjoint information sets. This class of codes contains self-dual codes as
+a subclass. It is connected to graph correlation immune Boolean functions of
+use in the security of hardware implementations of cryptographic primitives.
+Such codes permit to improve the cost of masking cryptographic algorithms
+against side channel attacks. In this paper we investigate this new class of
+codes: we give optimal or best known CIS codes of length $<132.$ We derive
+general constructions based on cyclic codes and on double circulant codes. We
+derive a Varshamov-Gilbert bound for long CIS codes, and show that they can all
+be classified in small lengths $\le 12$ by the building up construction. Some
+nonlinear permutations are constructed by using $\Z_4$-codes, based on the
+notion of dual distance of an unrestricted code.",1110.1193v2
+2011-10-31,Calculation of coercivity of magnetic nanostructures at finite temperatures,"We report a finite temperature micromagnetic method (FTM) that allows for the
+calculation of the coercive field of arbitrary shaped magnetic nanostructures
+at time scales of nanoseconds to years. Instead of directly solving the
+Landau-Lifshitz-Gilbert equation, the coercive field is obtained without any
+free parameter by solving a non linear equation, which arises from the
+transition state theory. The method is applicable to magnetic structures where
+coercivity is determined by one thermally activated reversal or nucleation
+process. The method shows excellent agreement with experimentally obtained
+coercive fields of magnetic nanostructures and provides a deeper understanding
+of the mechanism of coercivity.",1110.6789v1
+2011-11-10,Magnetic friction: From Stokes to Coulomb behavior,"We demonstrate that in a ferromagnetic substrate, which is continuously
+driven out of equilibrium by a field moving with constant velocity $v$, at
+least two types of friction may occur when $v$ goes to zero: The substrate may
+feel a friction force proportional to $v$ (Stokes friction), if the field
+changes on a time scale which is longer than the intrinsic relaxation time. On
+the other hand, the friction force may become independent of $v$ in the
+opposite case (Coulomb friction). These observations are analogous to e.g.
+solid friction. The effect is demonstrated in both, the Ising (one spin
+dimension) and the Heisenberg model (three spin dimensions), irrespective which
+kind of dynamics (Metropolis spin-flip dynamics or Landau-Lifshitz-Gilbert
+precessional dynamics) is used. For both models the limiting case of Coulomb
+friction can be treated analytically. Furthermore we present an empiric
+expression reflecting the correct Stokes behavior and therefore yielding the
+correct cross-over velocity and dissipation.",1111.2494v1
+2011-11-15,Revisiting No-Scale Supergravity Inspired Scenarios,"We consider no-scale supergravity inspired scenarios, emphasizing the
+possible dynamical determination of the soft supersymmetry-breaking parameters
+as triggered by the radiative corrections that lift an essentially flat
+tree-level potential in the hidden sector. We (re)emphasize the important role
+played by the scale-dependent vacuum energy contribution to the effective
+potential for the occurrence of consistent no-scale minima. The most relevant
+input parameters are introduced as $B_0$ (the soft breaking mixing Higgs
+parameter) and $\eta_0$ (the cosmological constant value at high energy)
+instead of $\mhalf$ and $\tan \beta$, the latter being determined through a
+(generalized) potential minimization at electroweak scales. We examine the
+theoretical and phenomenological viability of such a mechanism when confronted
+with up-to-date calculations of the low energy sparticle spectrum and with
+present constraints from the LHC and other observables. The tight dark matter
+relic density constraint for a neutralino LSP scenario can be considerably
+relaxed for a gravitino LSP scenario possible in this framework.",1111.3455v1
+2011-11-24,Spin-Wave Modes and Their Intense Excitation Effects in Skyrmion Crystals,"We theoretically study spin-wave modes and their intense excitations
+activated by microwave magnetic fields in the skyrmion-crystal phase of
+insulating magnets by numerically analyzing a two-dimensional spin model using
+the Landau-Lifshitz-Gilbert equation. Two peaks of spin-wave resonances with
+frequencies of ~1 GHz are found for in-plane a.c. magnetic field where
+distribution of the out-of-plane spin components circulates around each
+skyrmion core. Directions of the circulations are opposite between these two
+modes, and hence the spectra exhibit salient dependence on the circular
+polarization of irradiating microwave. A breathing-type mode is also found for
+out-of-plane a.c. magnetic field. By intensively exciting these collective
+modes, melting of the skyrmion crystal accompanied by a red shift of the
+resonant frequency is achieved within nano seconds.",1111.5667v1
+2011-11-26,Energy dissipation and switching delay in stress-induced switching of multiferroic devices in the presence of thermal fluctuations,"Switching the magnetization of a shape-anisotropic 2-phase multiferroic
+nanomagnet with voltage-generated stress is known to dissipate very little
+energy ($<$ 1 aJ for a switching time of $\sim$0.5 ns) at 0 K temperature.
+Here, we show by solving the stochastic Landau-Lifshitz-Gilbert equation that
+switching can be carried out with $\sim$100% probability in less than 1 ns
+while dissipating less than 2 aJ at {\it room temperature}. This makes
+nanomagnetic logic and memory systems, predicated on stress-induced magnetic
+reversal, one of the most energy-efficient computing hardware extant. We also
+study the dependence of energy dissipation, switching delay, and the critical
+stress needed to switch, on the rate at which stress is ramped up or down.",1111.6129v1
+2011-11-30,Multi-Weyl Topological Semimetals Stabilized by Point Group Symmetry,"We perform a complete classification of two-band $\bk\cdot\mathbf{p}$
+theories at band crossing points in 3D semimetals with $n$-fold rotation
+symmetry and broken time-reversal symmetry. Using this classification, we show
+the existence of new 3D topological semimetals characterized by
+$C_{4,6}$-protected double-Weyl nodes with quadratic in-plane (along $k_{x,y}$)
+dispersion or $C_6$-protected triple-Weyl nodes with cubic in-plane dispersion.
+We apply this theory to the 3D ferromagnet HgCr$_2$Se$_4$ and confirm it is a
+double-Weyl metal protected by $C_4$ symmetry. Furthermore, if the direction of
+the ferromagnetism is shifted away from the [001]- to the [111]-axis, the
+double-Weyl node splits into four single Weyl nodes, as dictated by the point
+group $S_6$ of that phase. Finally, we discuss experimentally relevant effects
+including splitting of multi-Weyl nodes by applying $C_n$ breaking strain and
+the surface Fermi arcs in these new semimetals.",1111.7309v2
+2011-12-01,Gate controlled Spin-Density Wave and Chiral FFLO Superconducting phases in interacting Quantum Spin Hall edge states,"We explore the phases exhibited by an interacting quantum spin Hall edge
+state in the presence of finite chemical potential (applied gate voltage) and
+spin imbalance (applied magnetic field). We find that the helical nature of the
+edge state gives rise to orders that are expected to be absent in non-chiral
+one-dimensional electronic systems. For repulsive interactions, the ordered
+state has an oscillatory spin texture whose ordering wavevector is controlled
+by the chemical potential. We analyze the manner in which a magnetic impurity
+provides signatures of such oscillations. We find that finite spin imbalance
+favors a finite current carrying groundstate that is not condensed in the
+absence of interactions and is superconducting for attractive interactions.
+This state is characterized by FFLO-type oscillations where the Cooper pairs
+obtain a finite center of mass momentum.",1112.0289v1
+2011-12-04,A New Approach to Incremental Cycle Detection and Related Problems,"We consider the problem of detecting a cycle in a directed graph that grows
+by arc insertions, and the related problems of maintaining a topological order
+and the strong components of such a graph. For these problems, we give two
+algorithms, one suited to sparse graphs, and the other to dense graphs. The
+former takes the minimum of O(m^{3/2}) and O(mn^{2/3}) time to insert m arcs
+into an n-vertex graph; the latter takes O(n^2 log(n)) time. Our sparse
+algorithm is considerably simpler than a previous O(m^{3/2})-time algorithm; it
+is also faster on graphs of sufficient density. The time bound of our dense
+algorithm beats the previously best time bound of O(n^{5/2}) for dense graphs.
+Our algorithms rely for their efficiency on topologically ordered vertex
+numberings; bounds on the size of the numbers give bound on running times.",1112.0784v1
+2011-12-05,Vortex core magnetization dynamics induced by thermal excitation,"We investigate the effect of temperature on the dynamic properties of
+magnetic vortices in small disks. Our calculations use a stochastic version of
+the Landau-Lifshitz-Gilbert (LLG) equation, valid for finite temperatures well
+below the Curie critical temperature. We show that a finite temperature induces
+a vortex precession around the center of the disk, even in the absence of other
+excitation sources. We discuss the origin and implications of the appearance of
+this new dynamics. We also show that a temperature gradient plays a role
+similar to that of a small constant magnetic field.",1112.0911v2
+2011-12-08,A 2-20 GHz Analog Lag-Correlator for Radio Interferometry,"We present the design and testing of a 2-20 GHz continuum band analog lag
+correlator with 16 frequency channels for astronomical interferometry. The
+correlator has been designed for future use with a prototype single-baseline
+interferometer operating at 185-275 GHz. The design uses a broadband Wilkinson
+divider tree with integral thin-film resistors implemented on an alumina
+substrate, and custom-made broadband InGaP/GaAs Gilbert Cell multipliers. The
+prototype correlator has been fully bench-tested, together with the necessary
+readout electronics for acquisition of the output signals. The results of these
+measurements show that the response of the correlator is well behaved over the
+band. An investigation of the noise behaviour also shows that the
+signal-to-noise of the system is not limited by the correlator performance.",1112.1982v1
+2011-12-12,An analysis of constraints on relativistic species from primordial nucleosynthesis and the cosmic microwave background,"We present constraints on the number of relativistic species from a joint
+analysis of cosmic microwave background (CMB) fluctuations and light element
+abundances (helium and deuterium) compared to big bang nucleosynthesis (BBN)
+predictions. Our BBN calculations include updates of nuclear rates in light of
+recent experimental and theoretical information, with the most significant
+change occuring for the d(p,gamma)^3He cross section. We calculate a likelihood
+function for BBN theory and observations that accounts for both observational
+errors and nuclear rate uncertainties and can be easily embedded in
+cosmological parameter fitting. We then demonstrate that CMB and BBN are in
+good agreement, suggesting that the number of relativistic species did not
+change between the time of BBN and the time of recombination. The level of
+agreement between BBN and CMB, as well as the agreement with the standard model
+of particle physics, depends somewhat on systematic differences among
+determinations of the primordial helium abundance. We demonstrate that
+interesting constraints can be derived combining only CMB and D/H observations
+with BBN theory, suggesting that an improved D/H constraint would be an
+extremely valuable probe of cosmology.",1112.2683v1
+2011-12-22,Higgs boson decay into 2 photons in the type~II Seesaw Model,"We study the two photon decay channel of the Standard Model-like component of
+the CP-even Higgs bosons present in the type II Seesaw Model. The corresponding
+cross-section is found to be significantly enhanced in parts of the parameter
+space, due to the (doubly-)charged Higgs bosons' $(H^{\pm \pm})H^\pm$ virtual
+contributions, while all the other Higgs decay channels remain Standard
+Model(SM)-like. In other parts of the parameter space $H^{\pm \pm}$ (and
+$H^{\pm}$) interfere destructively, reducing the two photon branching ratio
+tremendously below the SM prediction. Such properties allow to account for any
+excess such as the one reported by ATLAS/CMS at $\approx 125$ GeV if confirmed
+by future data; if not, for the fact that a SM-like Higgs exclusion in the
+diphoton channel around 114-115 GeV as reported by ATLAS, does not contradict a
+SM-like Higgs at LEP(!), and at any rate, for the fact that ATLAS/CMS exclusion
+limits put stringent lower bounds on the $H^{\pm \pm}$ mass, particularly in
+the parameter space regions where the direct limits from same-sign leptonic
+decays of $H^{\pm \pm}$ do not apply.",1112.5453v1
+2012-01-18,Cavity approach to sphere packing in Hamming space,"In this paper we study the hard sphere packing problem in the Hamming space
+by the cavity method. We show that both the replica symmetric and the replica
+symmetry breaking approximations give maximum rates of packing that are
+asymptotically the same as the lower bound of Gilbert and Varshamov.
+Consistently with known numerical results, the replica symmetric equations also
+suggest a crystalline solution, where for even diameters the spheres are more
+likely to be found in one of the subspaces (even or odd) of the Hamming space.
+These crystalline packings can be generated by a recursive algorithm which
+finds maximum packings in an ultra-metric space. Finally, we design a message
+passing algorithm based on the cavity equations to find dense packings of hard
+spheres. Known maximum packings are reproduced efficiently in non trivial
+ranges of dimensions and number of spheres.",1201.3863v2
+2012-01-19,"Impact of microstructure, temperature and strain ratio on energy-based low- cycle fatigue life prediction models for TiAl alloys","In this paper, two fatigue lifetime prediction models are tested on TiAl
+intermetallic using results from uniaxial low-cycle fatigue tests. Both
+assessments are based on dissipated energy but one of them considers a
+hydrostatic pressure correction. This work allows to confirm, on this kind of
+material, the linear nature, already noticed on silicon molybdenum cast iron,
+TiNi shape memory alloy and 304L stainless steel, of dissipated energy,
+corrected or not with hydrostatic pressure, according to the number of cycles
+to failure. This study also highlights that, firstly, the dissipated energy
+model is here more adequate to estimate low-cycle fatigue life and that,
+secondly, intrinsic parameters like microstructure as well as extrinsic
+parameters like temperature or strain ratio have an impact on prediction
+results.",1201.4084v1
+2012-01-23,Influence of the magnetoelectric coupling on the electric field induced magnetization reversal in a composite non-strained multiferroic chain,"We study theoretically the multiferroic dynamics in a composite
+one-dimensional system consisting of BaTiO3 multiferroically coupled to an iron
+chain. The method treats the magnetization and the polarization as
+thermodynamic quantities describable via a combination of the Landau-Lifshits-
+Gilbert and the Ginzburg-Landau dynamics coupled via an additional term in the
+total free energy density. This term stems from the multiferroic interaction at
+the interface. For a wide range of strengths of this coupling we predict the
+possibility of obtaining a well-developed hysteresis in the ferromagnetic part
+of the system induced by an external electric field. The dependence of the
+reversal modes on the electric field frequency is also investigated and we
+predict a considerable stability of the magnetization reversal for frequencies
+in the range of 0.5 - 12 [GHz].",1201.4740v1
+2012-01-27,Domain-wall complexes in ferromagnetic stripes,"Interaction of domain walls (DWs) in ferromagnetic stripes is studied with
+relevance to the formation of stable complexes of many domains. Two DW system
+is described with the Landau-Lifshitz-Gilbert equation including regimes of
+narrow and wide stripes which correspond the presence of transverse and vortex
+DWs. The DWs of both kinds are characterized with their chiralities (the
+direction of the magnetization rotation in the stripe plane) and polarities
+(the magnetization orientation in the center of a vortex and/or halfvortices),
+hence, their interactions are analyzed with dependence on these properties. In
+particular, pairs of the DWs of opposite or like both chiralities and
+polarities are investigated as well as pairs of opposite (like) chiralities and
+of like (opposite) polarities. Conditions of the creation of stationary
+magnetic bubbles built of two interacting DWs are formulated with relevance to
+the situations of presence and absence of the external magnetic field.",1201.5760v3
+2012-01-31,Interlayer Transport in Disordered Semiconductor Electron Bilayers,"We study the effects of disorder on the interlayer transport properties of
+disordered semiconductor bilayers outside of the quantum Hall regime by
+performing self-consistent quantum transport calculations. We find that the
+addition of material disorder to the system affects interlayer interactions
+leading to significant deviations in the interlayer transfer characteristics.
+In particular, we find that disorder decreases and broadens the tunneling peak,
+effectively reducing the interacting system to the non-interacting system, when
+the mean-free path for the electrons becomes shorter than the system length.
+Our results suggest that the experimental observation of exchange-enhanced
+interlayer transport in semiconductor bilayers requires materials with
+mean-free paths larger than the spatial extent of the system.",1202.0053v1
+2012-02-01,Imaging topologically protected transport with quantum degenerate gases,"Ultracold and quantum degenerate gases held near conductive surfaces can
+serve as sensitive, high resolution, and wide-area probes of electronic current
+flow. Previous work has imaged transport around grain boundaries in a gold wire
+by using ultracold and Bose-Einstein condensed atoms held microns from the
+surface with an atom chip trap. We show that atom chip microscopy may be
+applied to useful purpose in the context of materials exhibiting topologically
+protected surface transport. Current flow through lithographically tailored
+surface defects in topological insulators (TI)---both idealized and with the
+band-structure and conductivity typical of Bi$_{2}$Se$_{3}$---is numerically
+calculated. We propose that imaging current flow patterns enables the
+differentiation of an ideal TI from one with a finite bulk--to--surface
+conductivity ratio, and specifically, that the determination of this ratio may
+be possible by imaging transport around trenches etched into the TI's surface.",1202.0060v2
+2012-02-02,Large deviations and transitions between equilibria for stochastic Landau-Lifshitz-Gilbert equation,"We study a stochastic Landau-Lifshitz equation on a bounded interval and with
+finite dimensional noise. We first show that there exists a pathwise unique
+solution to this equation and that this solution enjoys the maximal regularity
+property. Next, we prove the large deviations principle for small noise
+asymptotic of solutions using the weak convergence method. An essential
+ingredient of the proof is compactness, or weak to strong continuity, of the
+solution map for a deterministic Landau-Lifschitz equation, when considered as
+a transformation of external fields. We then apply this large deviations
+principle to show that small noise can cause magnetisation reversal. We also
+show the importance of the shape anisotropy parameter for reducing the
+disturbance of the solution caused by small noise. The problem is motivated by
+applications of ferromagnetic nanowires to the fabrication of magnetic
+memories.
+  This is an updated version of the previous version of this paper.",1202.0370v2
+2012-02-06,Atomic level micromagnetic model of recording media switching at elevated temperatures,"An atomic level micromagnetic model of granular recording media is developed
+and applied to examine external field-induced grain switching at elevated
+temperatures which captures non-uniform reversal modes. The results are
+compared with traditional methods which employ the Landau-Lifshitz-Gilbert
+equations based on uniformly magnetized grains with assigned intrinsic
+temperature profiles for $M(T)$ and $K(T)$. Using nominal parameters
+corresponding to high-anisotropy FePt-type media envisioned for Energy Assisted
+Magnetic Recording, our results demonstrate that atomic-level reversal slightly
+reduces the field required to switch grains at elevated temperatures, but
+results in larger fluctuations, when compared to a uniformly magnetized grain
+model.",1202.1131v1
+2012-02-10,A model of magnetic order in hexagonal HoMnO3,"Symmetry arguments are used to develop a spin Hamiltonian for the description
+of the complex magnetic ordering in HoMnO$_3$. Using a novel application of the
+Landau Lifshitz Gilbert dynamic torque equations to this model of the
+frustrated Mn ions on an $AB$ stacked triangular antiferromagnetic, it is shown
+that the four principal spin configurations observed in this compound are
+stabilized. Ho-Mn coupling is found to be a consequence of an unusual trigonal
+anisotropy term which is responsible for simultaneous Mn spin reorientation and
+onset of Ho magnetic order. Based on these microscopic considerations, a
+mean-field Landau-type free energy is derived which reproduces the succession
+of observed temperature driven magnetic phase transitions at zero field,
+including re-entrant behavior. In addition, our analysis suggests that the
+basal-plane magnetic order should be slightly incommensurate with the lattice.",1202.2321v1
+2012-02-13,Switching Distributions for Perpendicular Spin-Torque Devices within the Macrospin Approximation,"We model ""soft"" error rates for writing (WSER) and for reading (RSER) for
+perpendicular spin-torque memory devices by solving the Fokker-Planck equation
+for the probability distribution of the angle that the free layer magnetization
+makes with the normal to the plane of the film. We obtain: (1) an exact, closed
+form, analytical expression for the zero-temperature switching time as a
+function of initial angle; (2) an approximate analytical expression for the
+exponential decay of the WSER as a function of the time the current is applied;
+(3) comparison of the approximate analytical expression for the WSER to
+numerical solutions of the Fokker-Planck equation; (4) an approximate
+analytical expression for the linear increase in RSER with current applied for
+reading; (5) comparison of the approximate analytical formula for the RSER to
+the numerical solution of the Fokker-Planck equation; and (6) confirmation of
+the accuracy of the Fokker-Planck solutions by comparison with results of
+direct simulation using the single-macrospin Landau-Lifshitz-Gilbert (LLG)
+equations with a random fluctuating field in the short-time regime for which
+the latter is practical.",1202.2621v1
+2012-02-13,Error- and Loss-Tolerances of Surface Codes with General Lattice Structures,"We propose a family of surface codes with general lattice structures, where
+the error-tolerances against bit and phase errors can be controlled
+asymmetrically by changing the underlying lattice geometries. The surface codes
+on various lattices are found to be efficient in the sense that their threshold
+values universally approach the quantum Gilbert-Varshamov bound. We find that
+the error-tolerance of surface codes depends on the connectivity of underlying
+lattices; the error chains on a lattice of lower connectivity are easier to
+correct. On the other hand, the loss-tolerance of surface codes exhibits an
+opposite behavior; the logical information on a lattice of higher connectivity
+has more robustness against qubit loss. As a result, we come upon a fundamental
+trade-off between error- and loss-tolerances in the family of the surface codes
+with different lattice geometries.",1202.2743v1
+2012-02-28,A method for exploratory repeated-measures analysis applied to a breast-cancer screening study,"When a model may be fitted separately to each individual statistical unit,
+inspection of the point estimates may help the statistician to understand
+between-individual variability and to identify possible relationships. However,
+some information will be lost in such an approach because estimation
+uncertainty is disregarded. We present a comparative method for exploratory
+repeated-measures analysis to complement the point estimates that was motivated
+by and is demonstrated by analysis of data from the CADET II breast-cancer
+screening study. The approach helped to flag up some unusual reader behavior,
+to assess differences in performance, and to identify potential random-effects
+models for further analysis.",1202.6133v1
+2012-03-15,"Size bias and differential lensing of strongly lensed, dusty galaxies identified in wide-field surveys","We address two selection effects that operate on samples of gravitationally
+lensed dusty galaxies identified in millimeter- and submillimeter-wavelength
+surveys. First, we point out the existence of a ""size bias"" in such samples:
+due to finite source effects, sources with higher observed fluxes are
+increasingly biased towards more compact objects. Second, we examine the effect
+of differential lensing in individual lens systems by modeling each source as a
+compact core embedded in an extended diffuse halo. Considering the ratio of
+magnifications in these two components, we find that at high overall
+magnifications the compact component is amplified by a much larger factor than
+the diffuse component, but at intermediate magnifications (~10) the probability
+of a larger magnification for the extended region is higher. Lens models
+determined from multi-frequency resolved imaging data are crucial to correct
+for this effect.",1203.3267v2
+2012-03-28,Decoherence and mode-hopping in a magnetic tunnel junction-based spin-torque oscillator,"We discuss the coherence of magnetic oscillations in a magnetic tunnel
+junction-based spin-torque oscillator as a function of external field angle.
+Time-frequency analysis shows mode-hopping between distinct oscillator modes,
+which arises from linear and nonlinear couplings in the Landau-Lifshitz-Gilbert
+equation, analogous to mode-hopping observed in semiconductor ring lasers.
+These couplings and therefore mode-hopping are minimized near the current
+threshold for antiparallel (AP) alignment of free layer with reference layer
+magnetization. Away from the AP alignment, mode-hopping limits oscillator
+coherence.",1203.6300v1
+2012-04-28,Topological Excitonic Superfluids in Three Dimensions,"We study the equilibrium and non-equilibrium properties of topological
+dipolar intersurface exciton condensates within time-reversal invariant
+topological insulators in three spatial dimensions without a magnetic field. We
+elucidate that, in order to correctly identify the proper pairing symmetry
+within the condensate order parameter, the full three-dimensional Hamiltonian
+must be considered. As a corollary, we demonstrate that only particles with
+similar chirality play a significant role in condensate formation. Furthermore,
+we find that the intersurface exciton condensation is not suppressed by the
+interconnection of surfaces in three-dimensional topological insulators as the
+intersurface polarizability vanishes in the condensed phase. This eliminates
+the surface current flow leaving only intersurface current flow through the
+bulk. We conclude by illustrating how the excitonic superfluidity may be
+identified through an examination of the terminal currents above and below the
+condensate critical current.",1204.6351v2
+2012-05-29,Thermally-Assisted Spin-Transfer Torque Magnetization Reversal in Uniaxial Nanomagnets,"We simulate the stochastic Landau-Lifshitz-Gilbert (LLG) dynamics of a
+uniaxial nanomagnet out to sub-millisecond timescales using a graphical
+processing unit based micromagnetic code and determine the effect of
+geometrical tilts between the spin-current and uniaxial anisotropy axes on the
+thermally assisted reversal dynamics. The asymptotic behavior of the switching
+time ($I\rightarrow 0$, $<\tau>\propto\exp(-\xi(1-I)^2)$) is approached
+gradually, indicating a broad crossover regime between ballistic and thermally
+assisted spin transfer reversal. Interestingly, the mean switching time is
+shown to be nearly independent of the angle between the spin current and
+magnet's uniaxial axes. These results have important implications for modeling
+the energetics of thermally assisted magnetization reversal of spin transfer
+magnetic random access memory bit cells.",1205.6509v1
+2012-06-06,Fractional Spin Josephson Effect and Electrically Controlled Magnetization in Quantum Spin Hall Edges,"We explore a spin Josephson effect in a system of two ferromagnets coupled by
+a tunnel junction formed of 2D time-reversal invariant topological insulators.
+In analogy with the more commonly studied instance of the Josephson effect for
+charge in superconductors, we investigate properties of the phase-coherent {\it
+spin} current resulting from the misalignment of the in-plane magnetization
+angles of the two ferromagnets. We show that the topological insulating barrier
+offers the exciting prospect of hosting a {\it fractional} spin Josephson
+effect mediated by bound states at the ferromagnet-topological insulator
+interface. We provide multiple perspectives to understand the $4\pi$ periodic
+nature of this effect. We discuss several measurable consequences, such as, the
+generation of a transverse voltage signal which allows for purely electrical
+measurements, an inverse of this effect where an applied voltage gives rise to
+a transverse spin-current, and a fractional AC spin-Josephson effect.",1206.1295v2
+2012-06-07,Magnetic particle hyperthermia: Power losses under circularly polarized field in anisotropic nanoparticles,"The deterministic Landau-Lifshitz-Gilbert equation has been used to
+investigate the nonlinear dynamics of magnetization and the specific loss power
+in magnetic nanoparticles with uniaxial anisotropy driven by a rotating
+magnetic field, generalizing the results obtained for the isotropic case found
+in [P. F. de Chatel, I. Nandori, J. Hakl, S. Meszaros and K. Vad, J. Phys.:
+Condens. Matter 21, 124202 (2009)]. As opposed to many applications of
+magnetization reversal in single-domain ferromagnetic particles where losses
+must be minimized, in this paper, we study the mechanisms of dissipation used
+in cancer therapy by hyperthermia which requires the enhancement of energy
+losses. We show that for circularly polarized field, the loss energy per cycle
+is decreased by the anisotropy compared to the isotropic case when only
+dynamical effects are taken into account. Thus, in this case, in the low
+frequency limit, a better heating efficiency can be achieved for isotropic
+nanoparticles. The possible role of thermal fluctuations is also discussed.
+Results obtained are compared to experimental data.",1206.1544v2
+2012-06-27,Searching for Fast Optical Transients using VERITAS Cherenkov Telescopes,"Astronomical transients are intrinsically interesting things to study. Fast
+optical transients (microsecond timescale) are a largely unexplored field of
+optical astronomy mainly due to the fact that large optical telescopes are
+oversubscribed. Furthermore, most optical observations use instruments with
+integration times on the order of seconds and are thus unable to resolve fast
+transients. Current-generation atmospheric Cherenkov gamma-ray telescopes,
+however, have huge collecting areas (e.g., VERITAS, which consists of four 12-m
+telescopes), larger than any existing optical telescopes, and time is typically
+available for such studies without interfering with gamma-ray observations. The
+following outlines the benefits of using a Cherenkov telescope to detect
+optical transients and the implementation of the VERITAS Transient Detector
+(TRenDy), a dedicated multi-channel photometer based on field-programmable gate
+arrays. Data are presented demonstrating the ability of TRenDy to detect
+transient events such as a star passing through its field of view and the
+optical light curve of a pulsar.",1206.6535v1
+2012-07-05,Perpendicular Magnetization and Generic Realization of the Ising Model in Artificial Spin Ice,"We have studied frustrated kagome arrays and unfrustrated honeycomb arrays of
+magnetostatically-interacting single-domain ferromagnetic islands with
+magnetization normal to the plane. The measured pairwise spin correlations of
+both lattices can be reproduced by models based solely on nearest-neighbor
+correlations. The kagome array has qualitatively different magnetostatics but
+identical lattice topology to previously-studied 'artificial spin ice' systems
+composed of in-plane moments. The two systems show striking similarities in the
+development of moment pair correlations, demonstrating a universality in
+artificial spin ice behavior independent of specific realization in a
+particular material system.",1207.1456v1
+2012-07-13,Magnetic vortices induced by a moving tip,"A two-dimensional easy-plane ferromagnetic substrate, interacting with a
+dipolar tip which is magnetised perpendicular with respect to the easy plane is
+studied numerically by solving the Landau-Lifshitz Gilbert equation. Due to the
+symmetry of the dipolar field of the tip, in addition to the collinear
+structure a magnetic vortex structure becomes stable. It is robust against
+excitations caused by the motion of the tip. We show that for high excitations
+the system may perform a transition between the two states. The influence of
+domain walls, which may also induce this transition, is examined.",1207.3225v2
+2012-07-30,'MOHAWK' : a 4000-fiber positioner for DESpec,"We present a concept for a 4000-fibre positioner for DESpec, based on the
+Echidna 'tilting spine' technology. The DESpec focal plane is 450mm across and
+curved, and the required pitch is ~6.75mm. The size, number of fibers and
+curvature are all comparable with various concept studies for similar
+instruments already undertaken at the AAO, but present new challenges in
+combination. A simple, low-cost, and highly modular design is presented,
+consisting of identical modules populated by identical spines. No show-stopping
+issues in accommodating either the curvature or the smaller pitch have been
+identified, and the actuators consist largely of off-the-shelf components. The
+actuators have been prototyped at AAO, and allow reconfiguration times of ~15s
+to reach position errors 7 microns or less. Straightforward designs for
+metrology, acquisition, and guiding are also proposed. The throughput losses of
+the entire positioner system are estimated to be ~15%, of which 6.3% is
+attributable to the tilting-spine technology.",1207.7011v2
+2012-07-31,Throughput of Rateless Codes over Broadcast Erasure Channels,"In this paper, we characterize the throughput of a broadcast network with n
+receivers using rateless codes with block size K. We assume that the underlying
+channel is a Markov modulated erasure channel that is i.i.d. across users, but
+can be correlated in time. We characterize the system throughput asymptotically
+in n. Specifically, we explicitly show how the throughput behaves for different
+values of the coding block size K as a function of n, as n approaches infinity.
+For finite values of K and n, under the more restrictive assumption of
+Gilbert-Elliott channels, we are able to provide a lower bound on the maximum
+achievable throughput. Using simulations we show the tightness of the bound
+with respect to system parameters n and K, and find that its performance is
+significantly better than the previously known lower bounds.",1207.7298v1
+2012-08-01,Streaming Codes for Channels with Burst and Isolated Erasures,"We study low-delay error correction codes for streaming recovery over a class
+of packet-erasure channels that introduce both burst-erasures and isolated
+erasures. We propose a simple, yet effective class of codes whose parameters
+can be tuned to obtain a tradeoff between the capability to correct burst and
+isolated erasures. Our construction generalizes previously proposed low-delay
+codes which are effective only against burst erasures. We establish an
+information theoretic upper bound on the capability of any code to
+simultaneously correct burst and isolated erasures and show that our proposed
+constructions meet the upper bound in some special cases. We discuss the
+operational significance of column-distance and column-span metrics and
+establish that the rate 1/2 codes discovered by Martinian and Sundberg [IT
+Trans.\, 2004] through a computer search indeed attain the optimal
+column-distance and column-span tradeoff. Numerical simulations over a
+Gilbert-Elliott channel model and a Fritchman model show significant
+performance gains over previously proposed low-delay codes and random linear
+codes for certain range of channel parameters.",1208.0072v1
+2012-08-23,Inconsistencies in the description of pairing effects in nuclear level densities,"Pairing correlations have a strong influence on nuclear level densities.
+Empirical descriptions and theoretical models have been developed to take these
+effects into account. The present article discusses cases, where descriptions
+of nuclear level densities are inconsistent or in conflict with the present
+understanding of nuclear properties. Phenomenological approaches consider a
+back-shift parameter. However, the absolute magnitude of the back-shift, which
+actually corresponds to the pairing condensation energy, is generally not
+compatible with the observation that stable pairing correlations are present in
+essentially all nuclei. It is also shown that in the BCS model pairing
+condensation energies and critical pairing energies are inconsistent for light
+nuclei. A modification to the composite Gilbert-Cameron level-density
+description is proposed, and the use of more realistic pairing theories is
+suggested.",1208.4709v1
+2012-09-26,Symmetry Protected Josephson Supercurrents in Three-Dimensional Topological Insulators,"Coupling the surface state of a topological insulator (TI) to an s-wave
+superconductor is predicted to produce the long-sought Majorana quasiparticle
+excitations. However, superconductivity has not been measured in surface states
+when the bulk charge carriers are fully depleted, i.e., in the true topological
+regime that is relevant for investigating Majorana modes. Here, we report
+measurements of DC Josephson effects in TI-superconductor junctions as the
+chemical potential is moved from the bulk bands into the band gap, or through
+the true topological regime characterized by the presence of only surface
+currents. We examine the relative behavior of the system at different
+bulk/surface ratios, determining the effects of strong bulk/surface mixing,
+disorder, and magnetic field. We compare our results to 3D quantum transport
+simulations to conclude that the supercurrent is largely carried by surface
+states, due to the inherent topology of the bands, and that it is robust
+against disorder.",1209.5830v2
+2012-10-09,A microscopic model for ultrafast remagnetization dynamics,"In this letter, we provide a microscopic model for the ultrafast
+remagnetization of atomic moments already quenched above Stoner-Curie
+temperature by a strong laser fluence. Combining first principles density
+functional theory, atomistic spin dynamics utilizing the
+Landau-Lifshitz-Gilbert equation and a three temperature model, we show the
+temporal evolution of atomic moments as well as the macroscopic magnetization
+of bcc Fe and hcp Co covering a broad time scale, ranging from femtoseconds to
+picoseconds. Our simulations show a variety of complex temporal behavior of the
+magnetic properties resulting from an interplay between electron, spin and
+lattice subsystems, which causes an intricate time evolution of the atomic
+moment, where longitudinal and transversal fluctuations result in a macro spin
+moment that evolves non-monotonically.",1210.2616v1
+2012-10-31,Theory and Simulation of the diffusion of kinks on dislocations in bcc metals,"Isolated kinks on thermally fluctuating (1/2)<111> screw, <100> edge and
+(1/2)<111> edge dislocations in bcc iron are simulated under zero stress
+conditions using molecular dynamics (MD). Kinks are seen to perform stochastic
+motion in a potential landscape that depends on the dislocation character and
+geometry, and their motion provides fresh insight into the coupling of
+dislocations to a heat bath. The kink formation energy, migration barrier and
+friction parameter are deduced from the simulations. A discrete
+Frenkel-Kontorova-Langevin (FKL) model is able to reproduce the coarse grained
+data from MD at a fraction of the computational cost, without assuming an a
+priori temperature dependence beyond the fluctuation-dissipation theorem.
+Analytic results reveal that discreteness effects play an essential r\^ole in
+thermally activated dislocation glide, revealing the existence of a crucial
+intermediate length scale between molecular and dislocation dynamics. The model
+is used to investigate dislocation motion under the vanishingly small stress
+levels found in the evolution of dislocation microstructures in irradiated
+materials.",1210.8327v2
+2012-11-01,Dynamically-generated pure spin current in single-layer graphene,"The conductance mismatch problem limits the spin-injection efficiency
+significantly, and spin-injection into graphene has been usually requiring
+high-quality tunnel barriers to circumvent the conductance mismatch. We
+introduce a novel approach, which enables generation of a pure spin current
+into single-layer graphene (SLG) free from electrical conductance mismatch by
+using dynamical spin injection. Experimental demonstration of
+spin-pumping-induced spin current generation and spin transport in SLG at room
+temperature was successfully achieved and the spin coherence was estimated to
+be 1.36 {\mu}m by using a conventional theoretical model based on
+Landau-Lifshitz-Gilbert equation. The spin coherence is proportional to the
+quality of SLG, which indicates that spin relaxation in SLG is governed by the
+Elliot-Yafet mechanism as was reported.",1211.0124v1
+2012-12-04,Phenomenological theory of the giant magnetoimpedance of composite wires,"Composite wires with a three-layered structure are known to show a
+particularly large magnetoimpedance effect. The wires consist of a highly
+conductive core, an insulating layer and an outer ferromagnetic shell. In order
+to understand the origin of the effect a theory based on a coupling of the
+Maxwell equations to the Landau-Lifschitz-Gilbert equation is suggested. The
+theory is phenomenological in the sense that it does not account for a domain
+structure. However, theoretical results nicely reproduce those obtained in
+various measurements. Furthermore, an upper limit of the magnetoimpedance ratio
+for a given combination of materials can be determined.",1212.0710v3
+2012-12-12,Giant magnetoimpedance of composite wires with an insulation layer,"Composite wires with a three-layered structure exhibit a large giant
+magneto-impedance (GMI) effect, which can be used in sensitive magnetic field
+sensors. To further investigate the origin of the GMI effect, composite wires
+consisting of a highly conductive copper core, a silicon dioxide layer and an
+outer Permalloy shell were prepared by radio frequency (RF) magnetron
+sputtering. The GMI ratio was measured at various driving current frequencies
+and with different insulating layer thicknesses. A theoretical model by
+coupling the Maxwell equations to the Landau-Lifschitz-Gilbert equation was
+developed to investigate the composite wire impedance and its dependence on
+external magnetic field, current frequency and insulating layer thickness.
+Experimental results corroborate the theoretical model.",1212.2745v2
+2012-12-13,Theory of quasiparticle interference in mirror symmetric 2D systems and its application to surface states of topological crystalline insulators,"We study symmetry protected features in the quasiparticle interference (QPI)
+pattern of 2D systems with mirror symmetries and time-reversal symmetry, around
+a single static point impurity. We show that, in the Fourier transformed local
+density of states (FT-LDOS), $\rho(\bq,\omega)$, while the position of high
+intensity peaks generically depends on the geometric features of the iso-energy
+contour at energy $\omega$, the \emph{absence} of certain peaks is guaranteed
+by the opposite mirror eigenvalues of the two Bloch states that are (i) on the
+mirror symmetric lines in the Brillouin zone (BZ) and (ii) separated by
+scattering vector $\bq$. We apply the general result to the QPI on the $ <{001}
+>$-surface of topological crystalline insulator Pb$_{1-x}$Sn$_x$Te and predict
+all vanishing peaks in $\rho(\bq,\omega)$. The model-independent analysis is
+supported by numerical calculations using an effective four-band model derived
+from symmetry analysis.",1212.3285v2
+2013-01-25,Chiral magnetism and helimagnons in a pyrochlore antiferromagnet,"Recent neutron scattering measurements on the spinel CdCr2O4 revealed a rare
+example of helical magnetic order in geometrically frustrated pyrochlore
+antiferromagnet. The spin spiral characterized by an incommensurate wavevector
+Q = 2pi (0, delta, 1) with delta ~0.09 is accompanied by a tetragonal
+distortion. Here we conduct a systematic study on the magnetic ground state
+resulting from the interplay between the Dzyaloshinskii-Moriya interaction and
+further neighbor exchange couplings, two of the most important mechanisms for
+stabilizing incommensurate spin orders. We compute the low-energy spin-wave
+spectrum based on a microscopic spin Hamiltonian and find a dispersion relation
+characteristic of the helimagnons. By numerically integrating the
+Landau-Lifshitz-Gilbert equation with realistic model parameters, an overall
+agreement between experiment and the numerical spectrum, lending further
+support to the view that a softened optical phonon triggers the magnetic
+transition and endows the lattice a chirality.",1301.5958v1
+2013-01-31,Switching of Dipole Coupled Multiferroic Nanomagnets in the Presence of Thermal Noise: Reliability of Nanomagnetic Logic,"The stress-induced switching behavior of a multiferroic nanomagnet, dipole
+coupled to a hard nanomagnet, is numerically studied by solving the stochastic
+Landau-Lifshitz-Gilbert (LLG) equation for a single domain macro-spin state.
+Different factors were found to affect the switching probability in the
+presence of thermal noise at room temperature: (i) dipole coupling strength,
+(ii) stress levels, and (iii) stress withdrawal rates (ramp rates). We report
+that the thermal broadening of the magnetization distribution causes large
+switching error rates. This could render nanomagnetic logic schemes that rely
+on dipole coupling to perform Boolean logic operations impractical whether they
+are clocked by stress or field or other means.",1301.7490v2
+2013-02-01,Vortex mechanics in planar nano-magnets,"A collective-variable approach for the study of non-linear dynamics of
+magnetic textures in planar nano-magnets is proposed. The variables are just
+arbitrary parameters (complex or real) in the specified analytical function of
+a complex variable, describing the texture in motion. Starting with such a
+function, a formal procedure is outlined, allowing a (non-linear) system of
+differential equations of motion to be obtained for the variables. The
+resulting equations are equivalent to Landau-Lifshitz-Gilbert dynamics as far
+as the definition of collective variables allows it. Apart from the
+collective-variable specification, the procedure does not involve any
+additional assumptions (such as translational invariance or steady-state
+motion). As an example, the equations of weakly non-linear motion of a magnetic
+vortex are derived and solved analytically. A simple formula for the dependence
+of the vortex precession frequency on its amplitude is derived. The results are
+verified against special cases from the literature and agree quantitatively
+with experiments and simulations.",1302.0222v3
+2013-02-03,Correcting Camera Shake by Incremental Sparse Approximation,"The problem of deblurring an image when the blur kernel is unknown remains
+challenging after decades of work. Recently there has been rapid progress on
+correcting irregular blur patterns caused by camera shake, but there is still
+much room for improvement. We propose a new blind deconvolution method using
+incremental sparse edge approximation to recover images blurred by camera
+shake. We estimate the blur kernel first from only the strongest edges in the
+image, then gradually refine this estimate by allowing for weaker and weaker
+edges. Our method competes with the benchmark deblurring performance of the
+state-of-the-art while being significantly faster and easier to generalize.",1302.0439v2
+2013-03-01,Entropy Distance,"Motivated by the approach of random linear codes, a new distance in the
+vector space over a finite field is defined as the logarithm of the ""surface
+area"" of a Hamming ball with radius being the corresponding Hamming distance.
+It is named entropy distance because of its close relation with entropy
+function. It is shown that entropy distance is a metric for a non-binary field
+and a pseudometric for the binary field. The entropy distance of a linear code
+is defined to be the smallest entropy distance between distinct codewords of
+the code. Analogues of the Gilbert bound, the Hamming bound, and the Singleton
+bound are derived for the largest size of a linear code given the length and
+entropy distance of the code. Furthermore, as an important property related to
+lossless joint source-channel coding, the entropy distance of a linear encoder
+is defined. Very tight upper and lower bounds are obtained for the largest
+entropy distance of a linear encoder with given dimensions of input and output
+vector spaces.",1303.0070v2
+2013-03-20,On the Behavior of RObust Header Compression U-mode in Channels with Memory,"The existing studies of RObust Header Compression (ROHC) have provided some
+understanding for memoryless channel, but the behavior of ROHC for correlated
+wireless channels is not well investigated in spite of its practical
+importance. In this paper, the dependence of ROHC against its design parameters
+for the Gilbert Elliot channel is studied by means of three analytical models.
+A first more elaborated approach accurately predicts the behavior of the
+protocol for the single RTP flow profile, while a simpler, analytically
+tractable model yields clear and insightful mathematical relationships that
+explain the qualitative trends of ROHC. The results are validated against a
+real world implementation of this protocol. Moreover, a third model studies
+also the less conventional yet practically relevant setting of multiple RTP
+flows.",1303.4970v1
+2013-03-21,Tuning magnetic anisotropy in (001) oriented L10 (Fe1-xCux)55Pt45 films,"We have achieved (001) oriented L10 (Fe1-xCux)55Pt45 thin films, with
+magnetic anisotropy up to 3.6x10^7 erg/cm^3, using atomic-scale multilayer
+sputtering and post annealing at 400 {\deg}C for 10 seconds. By fixing the Pt
+concentration, structure and magnetic properties are systematically tuned by
+the Cu addition. Increasing Cu content results in an increase in the tetragonal
+distortion of the L10 phase, significant changes to the film microstructure,
+and lowering of the saturation magnetization and anisotropy. The relatively
+convenient synthesis conditions, along with the tunable magnetic properties,
+make such materials highly desirable for future magnetic recording
+technologies.",1303.5208v1
+2013-03-28,Spin Torque on Magnetic Textures Coupled to the Surface of a Three-Dimensional Topological Insulator,"We investigate theoretically the spin torque and magnetization dynamic in a
+thin ferromagnetic (FM) layer with spatially varying magnetization. The FM
+layer is deposited on the surface of a topological insulator (TI). In the limit
+of the adiabatic relaxation of electron spin along the magnetization, the
+interaction between the exchange interaction and the Rashba-like surface
+texture of a TI yields a topological gauge field. Under the gauge field and an
+applied current, spin torque is induced according to the direction of the
+current. We derived the corresponding effective anisotropy field and hence the
+modified Landau-Lifshitz-Gilbert equation, which describes the spin torque and
+the magnetization dynamic. In addition, we study the effective field for
+exemplary magnetic textures, such as domain wall, skyrmion, and vortex
+configurations. The estimated strength of the effective field is comparable to
+the switching fields of typical FM materials, and hence can significantly
+influence the dynamics of the FM layer.",1303.7031v1
+2013-04-03,Synchronization of an array of spin torque nano oscillators in periodic applied external magnetic field,"Considering an array of spin torque transfer nano oscillators (STNOs), we
+have investigated the synchronization property of the system under the action
+of a common periodically driven applied external magnetic field by numerically
+analyzing the underlying system of Landau-Lifshitz-Gilbert-Slonczewski (LLGS)
+equations for the macro-spin variables. We find the novel result that the
+applied external magnetic field can act as a medium to induce synchronization
+of periodic oscillations, both in-phase and anti-phase, even without coupling
+through spin current, thereby leading to the exciting possibility of
+enhancement of microwave power in a straightforward way.",1304.0875v1
+2013-04-06,Towards a living earth simulator,"The Living Earth Simulator (LES) is one of the core components of the
+FuturICT architecture. It will work as a federation of methods, tools,
+techniques and facilities supporting all of the FuturICT simulation-related
+activities to allow and encourage interactive exploration and understanding of
+societal issues. Society-relevant problems will be targeted by leaning on
+approaches based on complex systems theories and data science in tight
+interaction with the other components of FuturICT. The LES will evaluate and
+provide answers to real-world questions by taking into account multiple
+scenarios. It will build on present approaches such as agent-based simulation
+and modeling, multiscale modelling, statistical inference, and data mining,
+moving beyond disciplinary borders to achieve a new perspective on complex
+social systems.",1304.1903v1
+2013-05-13,Backhopping effect in magnetic tunnel junctions: comparison between theory and experiment,"We report on the magnetic switching and backhopping effects due to
+spin-transfer-torque in magnetic tunnel junctions. Experimental data on the
+current-induced switching in junctions with MgO tunnel barrier reveal a random
+back-and-forth switching between the magnetization states, which appears when
+the current direction favors the parallel magnetic configuration. The effect
+depends on the barrier thickness $t_b$, and is not observed in tunnel junctions
+with very thin MgO tunnel barriers, $t_b$ $<$ 0.95 nm. Switching dependence on
+the bias voltage and barrier thickness is explained in terms of the macrospin
+model, with the magnetization dynamics described by the modified
+Landau-Lifshitz-Gilbert equation. Numerical simulations indicate that the
+competition between in-plane and out-of-plane torque components can result at
+high bias voltages in a non-deterministic switching behavior, in agreement with
+experimental observations. When the barrier thickness is reduced, the overall
+coupling between the magnetic layers across the barrier becomes ferromagnetic,
+which suppresses the backhopping effect.",1305.2711v1
+2013-05-15,Robust Streaming Erasure Codes based on Deterministic Channel Approximations,"We study near optimal error correction codes for real-time communication. In
+our setup the encoder must operate on an incoming source stream in a sequential
+manner, and the decoder must reconstruct each source packet within a fixed
+playback deadline of $T$ packets. The underlying channel is a packet erasure
+channel that can introduce both burst and isolated losses.
+  We first consider a class of channels that in any window of length ${T+1}$
+introduce either a single erasure burst of a given maximum length $B,$ or a
+certain maximum number $N$ of isolated erasures. We demonstrate that for a
+fixed rate and delay, there exists a tradeoff between the achievable values of
+$B$ and $N,$ and propose a family of codes that is near optimal with respect to
+this tradeoff. We also consider another class of channels that introduce both a
+burst {\em and} an isolated loss in each window of interest and develop the
+associated streaming codes.
+  All our constructions are based on a layered design and provide significant
+improvements over baseline codes in simulations over the Gilbert-Elliott
+channel.",1305.3596v1
+2013-05-16,Size-dependent magnetization switching characteristics and spin wave modes of FePt nanostructures,"We present a comprehensive investigation of the size-dependent switching
+characteristics and spin wave modes of FePt nanoelements. Curved nanomagnets
+(""caps"") are compared to flat disks of identical diameter and volume over a
+size range of 100 to 300nm. Quasi-static magnetization reversal analysis using
+first-order reversal curves (FORC) shows that spherical caps have lower vortex
+nucleation and annihilation fields than the flat disks. As the element diameter
+decreases, the reversal mechanism in the caps crosses over sooner to coherent
+rotation than in the disks. The magnetization dynamics are studied using
+optically induced small angle precession and reveal a strong size dependence
+that differs for the two shapes. Flat disks exhibit well-known center and edge
+modes at all sizes, but as the diameter of the caps increases from 100 to 300
+nm, additional oscillation modes appear in agreement with dynamic micromagnetic
+simulations. In addition, we show that the three-dimensional curvature of the
+cap causes a much greater sensitivity to the applied field angle which provides
+an additional way for controlling the ultrafast response of nanomagnetic
+elements.",1305.3686v1
+2013-05-28,Reallocation Problems in Scheduling,"In traditional on-line problems, such as scheduling, requests arrive over
+time, demanding available resources. As each request arrives, some resources
+may have to be irrevocably committed to servicing that request. In many
+situations, however, it may be possible or even necessary to reallocate
+previously allocated resources in order to satisfy a new request. This
+reallocation has a cost. This paper shows how to service the requests while
+minimizing the reallocation cost. We focus on the classic problem of scheduling
+jobs on a multiprocessor system. Each unit-size job has a time window in which
+it can be executed. Jobs are dynamically added and removed from the system. We
+provide an algorithm that maintains a valid schedule, as long as a sufficiently
+feasible schedule exists. The algorithm reschedules only a total number of
+O(min{log^* n, log^* Delta}) jobs for each job that is inserted or deleted from
+the system, where n is the number of active jobs and Delta is the size of the
+largest window.",1305.6555v1
+2013-06-04,Generalized splines on arbitrary graphs,"Let G be a graph whose edges are labeled by ideals of a commutative ring. We
+introduce a generalized spline, which is a vertex-labeling of G by elements of
+the ring so that the difference between the labels of any two adjacent vertices
+lies in the corresponding edge ideal. Generalized splines arise naturally in
+combinatorics (em algebraic splines of Billera and others) and in algebraic
+topology (certain equivariant cohomology rings, described by
+Goresky-Kottwitz-MacPherson and others). The central question of this
+manuscript asks when an arbitrary edge-labeled graph has nontrivial generalized
+splines. The answer is `always', and we prove the stronger result that
+generalized splines contain a free submodule whose rank is the number of
+vertices in G. We describe all generalized splines when G is a tree, and give
+several ways to describe the ring of generalized splines as an intersection of
+generalized splines for simpler subgraphs of G. We also present a new tool
+which we call the GKM matrix, an analogue of the incidence matrix of a graph,
+and end with open questions.",1306.0801v2
+2013-06-04,Large Chern Number Quantum Anomalous Hall Effect In Thin-film Topological Crystalline Insulators,"Quantum anomalous Hall (QAH) insulators are two-dimensional (2D) insulating
+states exhibiting properties similar to those of quantum Hall states but
+without external magnetic field. They have quantized Hall conductance
+$\sigma^H=Ce^2/h$, where integer $C$ is called the Chern number, and represents
+the number of gapless edge modes. Recent experiments demonstrated that chromium
+doped thin-film (Bi,Sb)$_2$Te$_3$ is a QAH insulator with Chern number
+$C=\pm1$. Here we theoretically predict that thin-film topological crystalline
+insulators (TCI) can host various QAH phases, when doped by ferromagnetically
+ordered dopants. Any Chern number between $\pm4$ can, in principle, be reached
+as a result of the interplay between (a) the induced Zeeman field, depending on
+the magnetic doping concentration, (b) the structural distortion, either
+intrinsic or induced by a piezoelectric material through proximity effect and
+(c) the thickness of the thin film. The tunable Chern numbers found in TCI
+possess significant potential for ultra-low power information processing
+applications.",1306.0888v2
+2013-06-07,Free energy generalization of the Peierls potential in iron,"In body-centered cubic (bcc) crystals, ${1}{2}111$ screw dislocations exhibit
+high intrinsic lattice friction as a consequence of their non-planar core
+structure, which results in a periodic energy landscape known as the Peierls
+potential, $U_P$. The main features determining plastic flow, including its
+stress and temperature dependences, can be derived directly from this
+potential, hence its importance. In this Letter, we use thermodynamic
+integration to provide a full thermodynamic extension of $U_P$ for bcc Fe. We
+compute the Peierls free energy path as a function of stress and temperature
+and show that the critical stress vanishes at 700K, supplying the qualitative
+elements that explain plastic behavior in the athermal limit.",1306.1633v4
+2013-06-14,On a decoupled linear FEM integrator for Eddy-current-LLG,"We propose a numerical integrator for the coupled system of the eddy-current
+equation with the nonlinear Landau-Lifshitz-Gilbert equation. The considered
+effective field contains a general field contribution, and we particularly
+cover exchange, anisotropy, applied field, and magnetic field (stemming from
+the eddy-current equation). Even though the considered problem is nonlinear,
+our scheme requires only the solution of two linear systems per time-step.
+Moreover, our algorithm decouples both equations so that in each time-step, one
+linear system is solved for the magnetization, and afterwards one linear system
+is solved for the magnetic field. Unconditional convergence -- at least of a
+subsequence -- towards a weak solution is proved, and our analysis even
+provides existence of such weak solutions. Numerical experiments with a
+micromagnetic benchmark problem underline the performance of the proposed
+algorithm.",1306.3319v1
+2013-06-20,"Lower Bounds for the Area of Black Holes in Terms of Mass, Charge, and Angular Momentum","The most general formulation of Penrose's inequality yields a lower bound for
+ADM mass in terms of the area, charge, and angular momentum of black holes.
+This inequality is in turn equivalent to an upper and lower bound for the area
+in terms of the remaining quantities. In this note, we establish the lower
+bound for a single black hole in the setting of axisymmetric maximal initial
+data sets for the Einstein-Maxwell equations, when the non-electromagnetic
+matter fields are not charged and satisfy the dominant energy condition. It is
+shown that the inequality is saturated if and only if the initial data arise
+from the extreme Kerr-Newman spacetime. Further refinements are given when
+either charge or angular momentum vanish. Lastly, we discuss the validity of
+the lower bound in the presence of multiple black holes.",1306.4739v2
+2013-06-28,Coherent Nonlinear Quantum Model for Composite Fermions,"Originally proposed by Read [1] and Jain [2], the so-called
+""composite-fermion"" is a phenomenological attachment of two infinitely thin
+local flux quanta seen as nonlocal vortices to two-dimensional (2D) electrons
+embedded in a strong orthogonal magnetic field. In this letter, it is described
+as a highly-nonlinear and coherent mean-field quantum process of the soliton
+type by use of a 2D stationary Schroedinger-Poisson differential model with
+only two Coulomb-interacting electrons. At filling factor $\nu={1}{3}$ of the
+lowest Landau level, it agrees with both the exact two-electron antisymmetric
+Schroedinger wave function and Laughlin's Jastrow-type guess for the fractional
+quantum Hall effect, hence providing this later with a tentative physical
+justification based on first principles.",1306.6869v1
+2013-06-29,First-principles calculations of current-induced spin-transfer torques in magnetic domain walls,"Current-induced spin-transfer torques (STTs) have been studied in Fe, Co and
+Ni domain walls (DWs) by the method based on the first-principles noncollinear
+calculations of scattering wave functions expanded in the tight-binding
+linearized muffin-tin orbital (TB-LMTO) basis. The results show that the
+out-of-plane component of nonadiabatic STT in Fe DW has localized form, which
+is in contrast to the typical nonlocal oscillating nonadiabatic torques
+obtained in Co and Ni DWs. Meanwhile, the degree of nonadiabaticity in STT is
+also much greater for Fe DW. Further, our results demonstrate that compared to
+the well-known first-order nonadiabatic STT, the torque in the third-order
+spatial derivative of local spin can better describe the distribution of
+localized nonadiabatic STT in Fe DW. The dynamics of local spin driven by this
+third-order torques in Fe DW have been investigated by the
+Landau-Lifshitz-Gilbert (LLG) equation. The calculated results show that with
+the same amplitude of STTs the DW velocity induced by this third-order term is
+about half of the wall speed for the case of the first-order nonadiabatic STT.",1307.0062v1
+2013-07-02,Reversal mode instability and magnetoresistance in perpendicular (Co/Pd)/Cu/(Co/Ni) pseudo-spin-valves,"We have observed distinct temperature-dependent magnetization reversal modes
+in a perpendicular (Co/Pd)4/Co/Cu/(Co/Ni)4/Co pseudo-spin-valve, which are
+correlated with spin-transport properties. At 300 K, magnetization reversal
+occurs by vertically correlated domains. Below 200 K the hysteresis loop
+becomes bifurcated due to laterally correlated reversal of the individual
+stacks. The magnetic configuration change also leads to higher spin disorders
+and a significant increase in the giant magnetoresistance effect. First order
+reversal curve measurements reveal that the coupled state can be re-established
+through field cycling, and allow direct determination of the interlayer
+coupling strength as a function of temperature.",1307.0853v1
+2013-07-08,Modal Analysis with Compressive Measurements,"Structural Health Monitoring (SHM) systems are critical for monitoring aging
+infrastructure (such as buildings or bridges) in a cost-effective manner. Such
+systems typically involve collections of battery-operated wireless sensors that
+sample vibration data over time. After the data is transmitted to a central
+node, modal analysis can be used to detect damage in the structure. In this
+paper, we propose and study three frameworks for Compressive Sensing (CS) in
+SHM systems; these methods are intended to minimize power consumption by
+allowing the data to be sampled and/or transmitted more efficiently. At the
+central node, all of these frameworks involve a very simple technique for
+estimating the structure's mode shapes without requiring a traditional CS
+reconstruction of the vibration signals; all that is needed is to compute a
+simple Singular Value Decomposition. We provide theoretical justification
+(including measurement bounds) for each of these techniques based on the
+equations of motion describing a simplified Multiple-Degree-Of-Freedom (MDOF)
+system, and we support our proposed techniques using simulations based on
+synthetic and real data.",1307.1960v1
+2013-07-15,On the Instabilities of the Walker Propagating Domain Wall Solution,"A powerful mathematical method for front instability analysis that was
+recently developed in the field of nonlinear dynamics is applied to the 1+1
+(spatial and time) dimensional Landau-Lifshitz-Gilbert (LLG) equation. From the
+essential spectrum of the LLG equation, it is shown that the famous Walker
+rigid body propagating domain wall (DW) is not stable against the spin wave
+emission. In the low field region only stern spin waves are emitted while both
+stern and bow waves are generated under high fields. By using the properties of
+the absolute spectrum of the LLG equation, it is concluded that in a high
+enough field, but below the Walker breakdown field, the Walker solution could
+be convective/absolute unstable if the transverse magnetic anisotropy is larger
+than a critical value, corresponding to a significant modification of the DW
+profile and DW propagating speed. Since the Walker solution of 1+1 dimensional
+LLG equation can be realized in experiments, our results could be also used to
+test the mathematical method in a controlled manner.",1307.3825v3
+2013-07-30,Accurate Decoding of Pooled Sequenced Data Using Compressed Sensing,"In order to overcome the limitations imposed by DNA barcoding when
+multiplexing a large number of samples in the current generation of
+high-throughput sequencing instruments, we have recently proposed a new
+protocol that leverages advances in combinatorial pooling design (group
+testing) doi:10.1371/journal.pcbi.1003010. We have also demonstrated how this
+new protocol would enable de novo selective sequencing and assembly of large,
+highly-repetitive genomes. Here we address the problem of decoding pooled
+sequenced data obtained from such a protocol. Our algorithm employs a
+synergistic combination of ideas from compressed sensing and the decoding of
+error-correcting codes. Experimental results on synthetic data for the rice
+genome and real data for the barley genome show that our novel decoding
+algorithm enables significantly higher quality assemblies than the previous
+approach.",1307.7810v1
+2013-08-09,Relativistic and thermal effects on the magnon spectrum of a ferromagnetic monolayer,"A spin model including magnetic anisotropy terms and Dzyaloshinsky-Moriya
+interactions is studied for the case of a ferromagnetic monolayer with C2v
+symmetry like Fe/W(110). Using the quasiclassical stochastic
+Landau-Lifshitz-Gilbert equations, the magnon spectrum of the system is derived
+using linear response theory. The Dzyaloshinsky-Moriya interaction leads to
+asymmetry in the spectrum, while the anisotropy terms induce a gap. It is shown
+that in the presence of lattice defects, both the Dzyaloshinsky-Moriya
+interactions and the two-site anisotropy lead to a softening of the magnon
+energies. Two methods are developed to investigate the magnon spectrum at
+finite temperatures. The theoretical results are compared to atomistic spin
+dynamics simulations and a good agreement is found between them.",1308.2082v2
+2013-08-11,New class of topological superconductors protected by magnetic group symmetries,"We study a new type of three-dimensional topological superconductors that
+exhibit Majorana zero modes (MZM) protected by a magnetic group symmetry, a
+combined antiunitary symmetry composed of a mirror reflection and
+time-reversal. This new symmetry enhances the noninteracting topological
+classification of a superconducting vortex from $Z_2$ to $Z$, indicating that
+multiple MZMs can coexist at the end of one magnetic vortex of unit flux.
+Specially, we show that a vortex binding two MZMs can be realized on the
+$(001)$-surface of a topological crystalline insulator SnTe with proximity
+induced BCS Cooper pairing, or in bulk superconductor In$_x$Sn$_{1-x}$Te.",1308.2424v3
+2013-08-26,A Radio-Frequency-over-Fiber link for large-array radio astronomy applications,"A prototype 425-850 MHz Radio-Frequency-over-Fiber (RFoF) link for the
+Canadian Hydrogen Intensity Mapping Experiment (CHIME) is presented. The design
+is based on a directly modulated Fabry-Perot (FP) laser, operating at ambient
+temperature, and a single-mode fiber. The dynamic performance, gain stability,
+and phase stability of the RFoF link are characterized. Tests on a two-element
+interferometer built at the Dominion Radio Astrophysical Observatory for CHIME
+prototyping demonstrate that RFoF can be successfully used as a cost-effective
+solution for analog signal transport on the CHIME telescope and other
+large-array radio astronomy applications",1308.5481v2
+2013-08-30,Energy dissipation of moved magnetic vortices,"A two-dimensional easy-plane ferromagnetic substrate, interacting with a
+dipolar tip which is magnetised perpendicular with respect to the easy plane is
+studied numerically by solving the Landau-Lifshitz Gilbert equation. The
+dipolar tip stabilises a vortex structure which is dragged through the system
+and dissipates energy. An analytical expression for the friction force in the
+v$\rightarrow$0-limit based on the Thiele equation is presented. The
+limitations of this result which predicts a diverging friction force in the
+thermodynamic limit, are demonstrated by a study of the size dependence of the
+friction force. While for small system sizes the dissipation depends
+logarithmically on the system size, it saturates at a specific velocity
+dependent value. This size can be regarded as an effective vortex size and it
+is shown how this effective vortex size agrees with the infinite extension of a
+vortex in the thermodynamic limit. A magnetic friction number is defined which
+represents a general criterion for the validity of the Thiele equation and
+quantifies the degree of nonlinearity in the response of a driven spin
+configuration.",1308.6714v1
+2013-10-16,Domain wall motion in magnetic nanowires: An asymptotic approach,"We develop a systematic asymptotic description for domain wall motion in
+one-dimensional magnetic nanowires under the influence of small applied
+magnetic fields and currents and small material anisotropy. The magnetization
+dynamics, as governed by the Landau--Lifshitz--Gilbert equation, is
+investigated via a perturbation expansion. We compute leading-order behaviour,
+propagation velocities, and first-order corrections of both travelling waves
+and oscillatory solutions, and find bifurcations between these two types of
+solutions. This treatment provides a sound mathematical foundation for numerous
+results in the literature obtained through more ad hoc arguments.",1310.4442v1
+2013-10-23,Exchange-dominated Standing Spin Wave Excitations under microwave irradiation in Ni80Fe20 Thin Films,"We investigated the microwave-assisted DC voltages of ferromagnetic
+resonances and exchangedominated standing spin wave excitations in two
+different in-plane magnetized permalloy thin films via homodyne detection. The
+line shapes of ferromagnetic resonance spectra and the dispersion curves of
+ferromagnetic resonance and standing spin wave are in agreement of previous
+studies, while further investigations of DC voltage spectra for these two
+excitations reveal that 1. unlike ferromagnetic resonance signals, the
+anti-symmetrical line shapes of standing spin wave excitations are not depend
+on the electromagnetic relative phase of assisted microwave, and 2. linewidths
+of their DC voltage spectra are distinct. The complicated spin dynamics of
+standing spin wave is consequently discussed by applying
+Landau-Lifshitz-Gilbert equation in term of exchange interaction.",1310.6108v1
+2013-10-25,Mode coupling in spin torque oscillators,"A number of recent experimental works have shown that the dynamics of a
+single spin torque oscillator can exhibit complex behavior that stems from
+interactions between two or more modes of the oscillator. Examples are observed
+mode-hopping or mode coexistence. There has been some intial work indicating
+how the theory for a single-mode (macro-spin) spin torque oscillator should be
+generalized to include several modes and the interactions between them. In the
+present work, we derive such a theory starting with the Landau-Lifshitz-Gilbert
+equation for magnetization dynamics. We compare our results with the
+single-mode theory, and show how it is a natural extension of that theory to
+include mode interactions.",1310.6791v2
+2013-10-31,A Labeling Approach to Incremental Cycle Detection,"In the \emph{incremental cycle detection} problem arcs are added to a
+directed acyclic graph and the algorithm has to report if the new arc closes a
+cycle. One seeks to minimize the total time to process the entire sequence of
+arc insertions, or until a cycle appears.
+  In a recent breakthrough, Bender, Fineman, Gilbert and Tarjan
+\cite{BeFiGiTa11} presented two different algorithms, with time complexity
+$O(n^2 \log n)$ and $O(m \cdot \min \{m^{1/2}, n^{2/3} \})$, respectively.
+  In this paper we introduce a new technique for incremental cycle detection
+that allows us to obtain both bounds (up to a logarithmic factor). Furthermore,
+our approach seems more amiable for distributed implementation.",1310.8381v1
+2013-11-01,Superfluid Spin Transport through Easy-Plane Ferromagnetic Insulators,"Superfluid spin transport $-$ dissipationless transport of spin $-$ is
+theoretically studied in a ferromagnetic insulator with easy-plane anisotropy.
+We consider an open geometry where spin current is injected into the
+ferromagnet from one side by a metallic reservoir with a nonequilibrium spin
+accumulation, and ejected into another metallic reservoir located downstream.
+Spin transport through the device is studied using a combination of
+magnetoelectric circuit theory, Landau-Lifshitz-Gilbert phenomenology, and
+microscopic linear-response theory. We discuss how spin superfluidity can be
+probed using a magnetically-mediated electron-drag experiment.",1311.0288v4
+2013-11-12,Vertex finiteness for splittings of relatively hyperbolic groups,"Consider a group G and a family $\mathcal{A}$ of subgroups of G. We say that
+vertex finiteness holds for splittings of G over $\mathcal{A}$ if, up to
+isomorphism, there are only finitely many possibilities for vertex stabilizers
+of minimal G-trees with edge stabilizers in $\mathcal{A}$.
+  We show vertex finiteness when G is a toral relatively hyperbolic group and
+$\mathcal{A}$ is the family of abelian subgroups.
+  We also show vertex finiteness when G is hyperbolic relative to virtually
+polycyclic subgroups and $\mathcal{A}$ is the family of virtually cyclic
+subgroups; if moreover G is one-ended, there are only finitely many minimal
+G-trees with virtually cyclic edge stabilizers, up to automorphisms of G.",1311.2835v2
+2013-11-13,Fokker-Planck approach to the theory of magnon-driven spin Seebeck effect,"Following the theoretical approach by Xiao et al [Phys. Rev. B 81, 214418
+(2010)] to the spin Seebeck effect, we calculate the mean value of the total
+spin current flowing through a normalmetal/ ferromagnet interface. The spin
+current emitted from the ferromagnet to the normal metal is evaluated in the
+framework of the Fokker-Planck approach for the stochastic
+Landau-Lifshitz-Gilbert equation. We show that the total spin current depends
+not only on the temperature difference between the electron and the magnon
+baths, but also on the external magnetic field and magnetic anisotropy. Apart
+from this, the spin current is shown to saturate with increasing magnon
+temperature, and the saturation temperature increases with increasing magnetic
+field and/or magnetic anisotropy.",1311.3117v1
+2013-11-20,Recent integral cross section validation measurements at the ASP facility,"This work presents new integral data measured at the ASP 14 MeV neutron
+irradiation facility at Aldermaston in the UK, which has recently become
+available for fusion-related work through the CCFE materials programme.
+Measurements of reaction products from activation experiments using elemental
+foils were carried out using gamma spectrometry in a high efficiency,
+high-purity germanium (HPGe) detector and associated digital signal processing
+hardware. Following irradiation and rapid extraction to the measurement cell,
+gamma emissions were acquired with both energy and time bins. Integral cross
+section and half-life data have been derived from these measurements. Selected
+integral cross section values are presented from the measurement campaigns.",1311.5074v1
+2013-11-25,Application of the Moment-SOS Approach to Global Optimization of the OPF Problem,"Finding a global solution to the optimal power flow (OPF) problem is
+difficult due to its nonconvexity. A convex relaxation in the form of
+semidefinite programming (SDP) has attracted much attention lately as it yields
+a global solution in several practical cases. However, it does not in all
+cases, and such cases have been documented in recent publications. This paper
+presents another SDP method known as the moment-sos (sum of squares) approach,
+which generates a sequence that converges towards a global solution to the OPF
+problem at the cost of higher runtime. Our finding is that in the small
+examples where the previously studied SDP method fails, this approach finds the
+global solution. The higher cost in runtime is due to an increase in the matrix
+size of the SDP problem, which can vary from one instance to another. Numerical
+experiment shows that the size is very often a quadratic function of the number
+of buses in the network, whereas it is a linear function of the number of buses
+in the case of the previously studied SDP method.",1311.6370v2
+2013-12-06,Lazy Cops and Robbers played on Graphs,"We consider a variant of the game of Cops and Robbers, called Lazy Cops and
+Robbers, where at most one cop can move in any round. We investigate the
+analogue of the cop number for this game, which we call the lazy cop number.
+Lazy Cops and Robbers was recently introduced by Offner and Ojakian, who
+provided asymptotic upper and lower bounds on the lazy cop number of the
+hypercube. By investigating expansion properties, we provide asymptotically
+almost sure bounds on the lazy cop number of binomial random graphs
+$\mathcal{G}(n,p)$ for a wide range of $p=p(n)$. By coupling the probabilistic
+method with a potential function argument, we also improve on the existing
+lower bounds for the lazy cop number of hypercubes. Finally, we provide an
+upper bound for the lazy cop number of graphs with genus $g$ by using the
+Gilbert-Hutchinson-Tarjan separator theorem.",1312.1750v1
+2014-01-03,Spin-Transfer-Torque Driven Magneto-Logic Gates Using Nano Spin-Valve Pillars,"We propose model magneto-logic NOR and NAND gates using a spin valve pillar,
+wherein the logical operation is induced by spin-polarized currents which also
+form the logical inputs. The operation is facilitated by the simultaneous
+presence of a constant controlling magnetic field. The same spin-valve assembly
+can also be used as a magnetic memory unit. We identify regions in the
+parameter space of the system where the logical operations can be effectively
+performed. The proposed gates retain the non-volatility of a magnetic random
+access memory,(MRAM). We verify the functioning of the gate by numerically
+simulating its dynamics, governed by the appropriate Landau-Lifshitz-Gilbert
+equation with the spin-transfer torque term. The flipping time for the logical
+states is estimated to be within nano seconds.",1401.0723v1
+2014-01-17,Diffuse Scattering on Graphs,"We formulate and analyze difference equations on graphs analogous to
+time-independent diffusion equations arising in the study of diffuse scattering
+in continuous media. Moreover, we show how to construct solutions in the
+presence of weak scatterers from the solution to the homogeneous (background
+problem) using Born series, providing necessary conditions for convergence and
+demonstrating the process through numerous examples. In addition, we outline a
+method for finding Green's functions for Cayley graphs for both abelian and
+non-abelian groups. Finally, we conclude with a discussion of the effects of
+sparsity on our method and results, outlining the simplifications that can be
+made provided that the scatterers are weak and well-separated.",1401.4428v2
+2014-01-25,"Linear Boolean classification, coding and ""the critical problem""","The problem of constructing a minimal rank matrix over GF(2) whose kernel
+does not intersect a given set S is considered. In the case where S is a
+Hamming ball centered at 0, this is equivalent to finding linear codes of
+largest dimension. For a general set, this is an instance of ""the critical
+problem"" posed by Crapo and Rota in 1970. This work focuses on the case where S
+is an annulus. As opposed to balls, it is shown that an optimal kernel is
+composed not only of dense but also of sparse vectors, and the optimal mixture
+is identified in various cases. These findings corroborate a proposed
+conjecture that for annulus of inner and outer radius nq and np respectively,
+the optimal relative rank is given by (1-q)H(p/(1-q)), an extension of the
+Gilbert-Varshamov bound H(p) conjectured for Hamming balls of radius np.",1401.6528v3
+2014-01-30,Langevin spin dynamics based on ab initio calculations: numerical schemes and applications,"A method is proposed to study the finite-temperature behaviour of small
+magnetic clusters based on solving the stochastic Landau-Lifshitz-Gilbert
+equations, where the effective magnetic field is calculated directly during the
+solution of the dynamical equations from first principles instead of relying on
+an effective spin Hamiltonian. Different numerical solvers are discussed in the
+case of a one-dimensional Heisenberg chain with nearest-neighbour interactions.
+We performed detailed investigations for a monatomic chain of ten Co atoms on
+top of Au(001) surface. We found a spiral-like ground state of the spins due to
+Dzyaloshinsky-Moriya interactions, while the finite-temperature magnetic
+behaviour of the system was well described by a nearest-neighbour Heisenberg
+model including easy-axis anisotropy.",1401.7885v2
+2014-02-25,Flux $1/f^α$ noise in 2D Heisenberg spin glasses: effects of weak anisotropic interactions,"We study the dynamics of a two-dimensional ensemble of randomly distributed
+classical Heisenberg spins with isotropic RKKY and weaker anisotropic
+dipole-dipole couplings. Such ensembles may give rise to the flux noise
+observed in SQUIDs with a $1/f^{\alpha}$ power spectrum ($\alpha \lesssim 1$).
+We solve numerically the Landau-Lifshiftz-Gilbert equations of motion in the
+dissipationless limit. We find that Ising type fluctuators, which arise from
+spin clustering close to a spin-glass critical behavior with $T_c =0$, give
+rise to $1/f^{\alpha}$ noise. Even weak anisotropic interactions lead to a
+crossover from the Heisenberg-type criticality to the much stronger Ising-type
+criticality. The temperature dependent exponent $\alpha(T) \lesssim 1$ grows
+and approaches unity when the temperature is lowered. This mechanism acts in
+parallel to the spin diffusion mechanism. Whereas the latter is sensitive to
+the device geometry, the spin-clustering mechanism is largely geometry
+independent.",1402.6229v2
+2014-02-25,Spinless Topological Insulators without Time-Reversal Symmetry,"We explore the 32 crystallographic point groups and identify topological
+phases of matter with robust surface modes. For n =3,4 and 6 of the C_{nv}
+groups, we find the first-known 3D topological insulators without spin-orbit
+coupling, and with surface modes that are protected only by point groups, i.e.,
+not needing time-reversal symmetry. To describe these C_{nv} systems, we
+introduce the notions of (a) a halved mirror chirality: an integer invariant
+which characterizes half-mirror-planes in the 3D Brillouin zone, and (b) a bent
+Chern number: the traditional TKNN invariant generalized to bent 2D manifolds.
+We find that a Weyl semimetallic phase intermediates two gapped phases with
+distinct halved chiralities.",1402.6323v1
+2014-04-08,Resonant Spin Wave Excitation by Terahertz Magnetic Near-field Enhanced with Split Ring Resonator,"Excitation of antiferromagnetic spin waves in HoFeO$_{3}$ crystal combined
+with a split ring resonator (SRR) is studied using terahertz (THz)
+electromagnetic pulses. The magnetic field in the vicinity of the SRR induced
+by the incident THz electric field component excites and the Faraday rotation
+of the polarization of a near-infrared probe pulse directly measures
+oscillations that correspond to the antiferromagnetic spin resonance mode. The
+good agreement of the temperature-dependent magnetization dynamics with the
+calculation using the two-lattice Landau-Lifshitz-Gilbert equation confirms
+that the spin wave is resonantly excited by the THz magnetic near-field
+enhanced at the LC resonance frequency of the SRR, which is 20 times stronger
+than the incident magnetic field.",1404.2179v1
+2014-04-09,Spin switches for compact implementation of neuron and synapse,"Nanomagnets driven by spin currents provide a natural implementation for a
+neuron and a synapse: currents allow convenient summation of multiple inputs,
+while the magnet provides the threshold function. The objective of this paper
+is to explore the possibility of a hardware neural network (HNN) implementation
+using a spin switch (SS) as its basic building block. SS is a recently proposed
+device based on established technology with a transistor-like gain and
+input-output isolation. This allows neural networks to be constructed with
+purely passive interconnections without intervening clocks or amplifiers. The
+weights for the neural network are conveniently adjusted through analog
+voltages that can be stored in a non-volatile manner in an underlying CMOS
+layer using a floating gate low dropout voltage regulator. The operation of a
+multi-layer SS neural network designed for character recognition is
+demonstrated using a standard simulation model based on coupled
+Landau-Lifshitz-Gilbert (LLG) equations, one for each magnet in the network.",1404.2654v2
+2014-06-30,Coercivity reduction in a two-dimensional array of nanoparticles,"We report on theoretical investigation of the magnetization reversal in
+two-dimensional arrays of ferromagnetic nano-particles with parameters of
+cobalt. The system was optimized for achieving the lowest coercivity in an
+array of particles located in the nodes of triangular, hexagonal and square
+grids. Based on the numerical solution of the non-stochastic
+Landau-Lifshitz-Gilbert equation we show that each particle distribution type
+is characterized with a proper optimal distance, allowing to lower the
+coercivity values for approximately 30% compared with the reference value
+obtained for a single nano-particle. It was shown that the reduction of
+coercivity occurs even if the particle position in the array is not very
+precise. In particular, the triangular particle arrangement maintained the same
+optimal distance between the particles under up to 20% random displacements of
+their position within the array.",1406.7786v1
+2014-07-17,Spatial ordering of nano-dislocation loops in ion-irradiated materials,"Defect microstructures formed in ion-irradiated metals, for example iron or
+tungsten, often exhibit patterns of spatially ordered nano-scale dislocation
+loops. We show that such ordered dislocation loop structures may form
+spontaneously as a result of Brownian motion of loops, biased by the
+angular-dependent elastic interaction between the loops. Patterns of spatially
+ordered loops form once the local density of loops produced by ion irradiation
+exceeds a critical threshold value.",1407.4683v1
+2014-07-22,"Lattice swelling and modulus change in a helium-implanted tungsten alloy: X-ray micro-diffraction, surface acoustic wave measurements, and multiscale modelling","Using X-ray micro-diffraction and surface acoustic wave spectroscopy, we
+measure lattice swelling and elastic modulus changes in a W-1%Re alloy after
+implantation with 3110 appm of helium. A fraction of a percent observed lattice
+expansion gives rise to an order of magnitude larger reduction in the surface
+acoustic wave velocity. A multiscale elasticity, molecular dynamics, and
+density functional theory model is applied to the interpretation of
+observations. The measured lattice swelling is consistent with the relaxation
+volume of self-interstitial and helium-filled vacancy defects that dominate the
+helium-implanted material microstructure. Molecular dynamics simulations
+confirm the elasticity model for swelling. Elastic properties of the implanted
+surface layer also change due to defects. The reduction of surface acoustic
+wave velocity predicted by density functional theory calculations agrees
+remarkably well with experimental observations.",1407.6051v1
+2014-07-26,Principles and Parameters: a coding theory perspective,"We propose an approach to Longobardi's parametric comparison method (PCM) via
+the theory of error-correcting codes. One associates to a collection of
+languages to be analyzed with the PCM a binary (or ternary) code with one code
+words for each language in the family and each word consisting of the binary
+values of the syntactic parameters of the language, with the ternary case
+allowing for an additional parameter state that takes into account phenomena of
+entailment of parameters. The code parameters of the resulting code can be
+compared with some classical bounds in coding theory: the asymptotic bound, the
+Gilbert-Varshamov bound, etc. The position of the code parameters with respect
+to some of these bounds provides quantitative information on the variability of
+syntactic parameters within and across historical-linguistic families. While
+computations carried out for languages belonging to the same family yield codes
+below the GV curve, comparisons across different historical families can give
+examples of isolated codes lying above the asymptotic bound.",1407.7169v1
+2014-07-28,Eddy current effects in the magnetization dynamics of ferromagnetic metal nanoparticles,"We develop an analytical model for describing the magnetization dynamics in
+ferromagnetic metal nanoparticles, which is based on the coupled system of the
+Landau-Lifshitz-Gilbert (LLG) and Maxwell equations. By solving Maxwell's
+equations in the quasi-static approximation and finding the magnetic field of
+eddy currents, we derive the closed LLG equation for the magnetization that
+fully accounts for the effects of conductivity. We analyze the difference
+between the LLG equations in metallic and dielectric nanoparticles and show
+that these effects can strongly influence the magnetization dynamics. As an
+example illustrating the importance of eddy currents, the phenomenon of
+precessional switching of magnetization is considered.",1407.7466v1
+2014-08-02,Standards for Graph Algorithm Primitives,"It is our view that the state of the art in constructing a large collection
+of graph algorithms in terms of linear algebraic operations is mature enough to
+support the emergence of a standard set of primitive building blocks. This
+paper is a position paper defining the problem and announcing our intention to
+launch an open effort to define this standard.",1408.0393v1
+2014-08-02,McCool groups of toral relatively hyperbolic groups,"The outer automorphism group Out(G) of a group G acts on the set of conjugacy
+classes of elements of G. McCool proved that the stabilizer $Mc(c_1,...,c_n)$
+of a finite set of conjugacy classes is finitely presented when G is free. More
+generally, we consider the group $Mc(H_1,...,H_n)$ of outer automorphisms
+$\Phi$ of G acting trivially on a family of subgroups $H_i$, in the sense that
+$\Phi$ has representatives $\alpha_i$ with $\alpha_i$ equal to the identity on
+$H_i$.
+  When G is a toral relatively hyperbolic group, we show that these two
+definitions lead to the same subgroups of Out(G), which we call ""McCool groups""
+of G. We prove that such McCool groups are of type VF (some finite index
+subgroup has a finite classifying space). Being of type VF also holds for the
+group of automorphisms of G preserving a splitting of G over abelian groups.
+  We show that McCool groups satisfy a uniform chain condition: there is a
+bound, depending only on G, for the length of a strictly decreasing sequence of
+McCool groups of G. Similarly, fixed subgroups of automorphisms of G satisfy a
+uniform chain condition.",1408.0418v1
+2014-08-06,The first SPIE software Hack Day,"We report here on the software Hack Day organised at the 2014 SPIE conference
+on Astronomical Telescopes and Instrumentation in Montreal. The first ever Hack
+Day to take place at an SPIE event, the aim of the day was to bring together
+developers to collaborate on innovative solutions to problems of their choice.
+Such events have proliferated in the technology community, providing
+opportunities to showcase, share and learn skills. In academic environments,
+these events are often also instrumental in building community beyond the
+limits of national borders, institutions and projects. We show examples of
+projects the participants worked on, and provide some lessons learned for
+future events.",1408.1278v1
+2014-08-07,A broadband silicon quarter-wave retarder for far-infrared spectroscopic circular dichroism,"The high brightness, broad spectral coverage and pulsed characteristics of
+infrared synchrotron radiation enable time-resolved spectroscopy under
+throughput-limited optical systems, as can occur with the high-field magnet
+cryostat systems used to study electron dynamics and cyclotron resonance by
+far-infrared techniques. A natural extension for magnetospectroscopy is to
+sense circular dichroism, i.e. the difference in a material's optical response
+for left and right circularly polarized light. A key component for
+spectroscopic circular dichroism is an achromatic 1/4 wave retarder functioning
+over the spectral range of interest. We report here the development of an
+in-line retarder using total internal reflection in high-resistivity silicon.
+We demonstrate its performance by distinguishing electronic excitations of
+different handednesses for GaAs in a magnetic field. This 1/4 wave retarder is
+expected to be useful for far-infrared spectroscopy of circular dichroism in
+many materials.",1408.1650v1
+2014-08-12,Probing the A1 to L10 Transformation in FeCuPt Using the First Order Reversal Curve Method,"The A1- L10 phase transformation has been investigated in (001) FeCuPt thin
+films prepared by atomic-scale multilayer sputtering and rapid thermal
+annealing (RTA). Traditional x-ray diffraction is not always applicable in
+generating a true order parameter, due to non-ideal crystallinity of the A1
+phase. Using the first-order reversal curve (FORC) method, the A1 and L10
+phases are deconvoluted into two distinct features in the FORC distribution,
+whose relative intensities change with the RTA temperature. The L10 ordering
+takes place via a nucleation-and-growth mode. A magnetization-based phase
+fraction is extracted, providing a quantitative measure of the L10 phase
+homogeneity.",1408.2860v1
+2014-09-09,Magnetization pumping and dynamics in a Dzyaloshinskii-Moriya magnet,"We formulate a phenomenological description of thin ferromagnetic layers with
+inversion asymmetry where the single-domain magnetic dynamics experiences
+magnon current-induced torques and leads to magnon-motive forces. We first
+construct a phenomenological theory based on irreversible thermodynamics,
+taking into account the symmetries of the system. Furthermore, we confirm that
+these effects originate from Dzyaloshinskii-Moriya interactions from the
+analysis based on the stochastic Landau-Lifshitz-Gilbert equation. Our
+phenomenological results generalize to a general form of Dzyaloshinskii-Moriya
+interactions and to other systems, such as pyrochlore crystals and chiral
+magnets. Possible applications include spin current generation, magnetization
+reversal and magnonic cooling.",1409.2846v3
+2014-09-17,Communities and Hierarchical Structures in Dynamic Social Networks: Analysis and Visualization,"Detection of community structures in social networks has attracted lots of
+attention in the domain of sociology and behavioral sciences. Social networks
+also exhibit dynamic nature as these networks change continuously with the
+passage of time. Social networks might also present a hierarchical structure
+led by individuals that play important roles in a society such as Managers and
+Decision Makers. Detection and Visualization of these networks changing over
+time is a challenging problem where communities change as a function of events
+taking place in the society and the role people play in it.
+  In this paper we address these issues by presenting a system to analyze
+dynamic social networks. The proposed system is based on dynamic graph
+discretization and graph clustering. The system allows detection of major
+structural changes taking place in social communities over time and reveals
+hierarchies by identifying influential people in a social networks. We use two
+different data sets for the empirical evaluation and observe that our system
+helps to discover interesting facts about the social and hierarchical
+structures present in these social networks.",1409.5040v1
+2014-09-30,Free upper boundary value problems for the semi-geostrophic equations,"The semi-geostrophic system is widely used in the modelling of large-scale
+atmospheric flows. In this paper, we prove existence of solutions of the
+incompressible semi-geostrophic equations in a fully three-dimensional domain
+with a free upper boundary condition.
+  We show that, using methods similar to those introduced in the pioneering
+work of Benamou and Brenier, who analysed the same system but with a rigid
+boundary condition, we can prove the existence of solutions for the
+incompressible free boundary problem. The proof is based on optimal transport
+results as well as the analysis of Hamiltonian ODEs in spaces of probability
+measures given by Ambrosio and Gangbo. We also show how these techniques can be
+modified to yield the same result also for the compressible version of the
+system.",1409.8560v3
+2014-10-21,Voltage Induced Dynamical Quantum Phase Transitions in Exciton Condensates,"We explore non-analytic quantum phase dynamics of dipolar exciton condensates
+formed in a system of 1D quantum layers subjected to voltage quenches. We map
+the exciton condensate physics on to the pseudospin ferromagnet model showing
+an additional oscillatory metastable and paramagnetic phase beyond the
+well-known ferromagnetic phase by utilizing a time-dependent, non-perturbative
+theoretical model. We explain the coherent phase of the exciton condensate in
+quantum Hall bilayers, observed for currents equal to and slightly larger than
+the critical current, as a stable time-dependent phase characterized by
+persistent charged meron flow in each of the individual layers with a
+characteristic AC Josephson frequency. As the magnitude of the voltage quench
+is further increased, we find that the time-dependent current oscillations
+associated with the charged meron flow decay, resulting in a transient
+pseudospin paramagnet phase characterized by partially coherent charge transfer
+between layers, before the state relaxes to incoherent charge transfer between
+the layers.",1410.5564v1
+2014-10-22,Landau-Lifshitz-Bloch equation for exchange coupled grains,"Heat assisted recording is a promising technique to further increase the
+storage density in hard disks. Multilayer recording grains with graded Curie
+temperature is discussed to further assist the write process. Describing the
+correct magnetization dynamics of these grains, from room temperature to far
+above the Curie point, during a write process is required for the calculation
+of bit error rates. We present a coarse grained approach based on the
+Landau-Lifshitz-Bloch (LLB) equation to model exchange coupled grains with low
+computational effort. The required temperature dependent material properties
+such as the zero-field equilibrium magnetization as well as the parallel and
+normal susceptibilities are obtained by atomistic Landau-Lifshitz-Gilbert (LLG)
+simulations. Each grain is described with one magnetization vector. In order to
+mimic the atomistic exchange interaction between the grains a special treatment
+of the exchange field in the coarse grained approach is presented.",1410.6066v2
+2014-10-22,A three-dimensional spin-diffusion model for micromagnetics,"We implement a finite-element scheme that solves the Landau-Lifshitz-Gilbert
+equation coupled to a diffusion equation accounting for spin-polarized
+currents. The latter solves for the spin accumulation not only in magnetic
+materials but also in nonmagnetic conductors. The presented method incorporates
+the model by Slonczewski for the description of spin torque in magnetic
+multilayers as well as the model of Zhang and Li for the description of current
+driven domain-wall motion. Furthermore it is able to do both resolve the time
+evolution of the spin accumulation or treat it in an adiabatic fashion by the
+choice of sufficiently large time steps.",1410.6067v2
+2014-11-13,Random geometric graphs with general connection functions,"In the original (1961) Gilbert model of random geometric graphs, nodes are
+placed according to a Poisson point process, and links formed between those
+within a fixed range. Motivated by wireless ad-hoc networks ""soft"" or
+""probabilistic"" connection models have recently been introduced, involving a
+""connection function"" H(r) that gives the probability that two nodes at
+distance r are linked (directly connect). In many applications (not only
+wireless networks), it is desirable that the graph is connected, that is every
+node is linked to every other node in a multihop fashion. Here, the connection
+probability of a dense network in a convex domain in two or three dimensions is
+expressed in terms of contributions from boundary components, for a very
+general class of connection functions. It turns out that only a few quantities
+such as moments of the connection function appear. Good agreement is found with
+special cases from previous studies and with numerical simulations.",1411.3617v3
+2014-11-24,Enhancement of Spin-transfer torque switching via resonant tunneling,"We propose the use of resonant tunneling as a route to enhance the
+spin-transfer torque switching characteristics of magnetic tunnel junctions.
+The proposed device structure is a resonant tunneling magnetic tunnel junction
+based on a MgO-semiconductor heterostructure sandwiched between a fixed magnet
+and a free magnet. Using the non-equilibrium Green's function formalism coupled
+self consistently with the Landau-Lifshitz-Gilbert-Slonczewski equation, we
+demonstrate enhanced tunnel magneto-resistance characteristics as well as lower
+switching voltages in comparison with traditional trilayer devices. Two device
+designs based on MgO based heterostructures are presented, where the physics of
+resonant tunneling leads to an enhanced spin transfer torque thereby reducing
+the critical switching voltage by up to 44%. It is envisioned that the
+proof-of-concept presented here may lead to practical device designs via
+rigorous materials and interface studies.",1411.6454v1
+2014-12-22,Langevin dynamics for vector variables driven by multiplicative white noise: a functional formalism,"We discuss general multi-dimensional stochastic processes driven by a system
+of Langevin equations with multiplicative white noise. In particular, we
+address the problem of how time reversal diffusion processes are affected by
+the variety of conventions available to deal with stochastic integrals. We
+present a functional formalism to built up the generating functional of
+correlation functions without any type of discretization of the Langevin
+equations at any intermediate step. The generating functional is characterized
+by a functional integration over two sets of commuting variables as well as
+Grassmann variables. In this representation, time reversal transformation
+became a linear transformation in the extended variables, simplifying in this
+way the complexity introduced by the mixture of prescriptions and the
+associated calculus rules. The stochastic calculus is codified in our formalism
+in the structure of the Grassmann algebra. We study some examples such as
+higher order derivatives Langevin equations and the functional representation
+of the micromagnetic stochastic Landau-Lifshitz-Gilbert equation.",1412.7015v2
+2014-12-30,"Mapping tori of free group automorphisms, and the Bieri-Neumann-Strebel invariant of graphs of groups","Let $G$ be the mapping torus of a polynomially growing automorphism of a
+finitely generated free group. We determine which epimorphisms from $G$ to
+$\mathbb{Z}$ have finitely generated kernel, and we compute the rank of the
+kernel. We thus describe all possible ways of expressing $G$ as the mapping
+torus of a free group automorphism. This is similar to the case for 3--manifold
+groups, and different from the case of mapping tori of exponentially growing
+free group automorphisms. The proof uses a hierarchical decomposition of $G$
+and requires determining the Bieri-Neumann-Strebel invariant of the fundamental
+group of certain graphs of groups.",1412.8582v1
+2015-01-12,Magnetic correlations beyond the Heisenberg model in an Fe monolayer on Rh(001),"Motivated by a recent experimental observation of a complex magnetic
+structure [Takada et al. 2013 J. Magn. Magn. Mater. 329 95] we present a
+theoretical study of the magnetic structure of an Fe monolayer deposited on
+Rh(001). We use a classical spin Hamiltonian with parameters obtained from ab
+initio calculations and go beyond the usual anisotropic Heisenberg model by
+including isotropic biquadratic interactions. Zero-temperature
+Landau--Lifshitz--Gilbert spin dynamics simulations lead to a complex collinear
+spin configuration that, however, contradicts experimental finding. We thus
+conclude that higher order multi-spin interactions are likely needed to account
+for the magnetic ordering of the system.",1501.02657v1
+2015-01-22,Relativistic dynamical spin excitations of magnetic adatoms,"We present a first-principles theory of dynamical spin excitations in the
+presence of spin-orbit coupling. The broken global spin rotational invariance
+leads to a new sum rule. We explore the competition between the magnetic
+anisotropy energy and the external magnetic field, as well as the role of
+electron-hole excitations, through calculations for 3$d$-metal adatoms on the
+Cu(111) surface. The spin excitation resonance energy and lifetime display
+non-trivial behavior, establishing the strong impact of relativistic effects.
+We legitimate the use of the Landau-Lifshitz-Gilbert equation down to the
+atomic limit, but with parameters that differ from a stationary theory.",1501.05509v1
+2015-01-23,Tuning Range-Separated Density Functional Theory for Photocatalytic Water Splitting Systems,"We discuss the system-specific optimization of long-range separated density
+functional theory (DFT) for the prediction of electronic properties relevant
+for a photocatalytic cycle based on an Ir(III) photosensitizer (IrPS). Special
+attention is paid to the charge-transfer properties, which are of key
+importance for the photoexcitation dynamics, but and cannot be correctly
+described by means of conventional DFT. The optimization of the
+range-separation parameter using the $\Delta$SCF method is discussed for IrPS
+including its derivatives and complexes with electron donors and acceptors used
+in photocatalytic hydrogen production. Particular attention is paid to the
+problems arising for a description of medium effects by means of a polarizable
+continuum model.",1501.05863v2
+2015-01-26,Dynamics of magnon fluid in Dzyaloshinskii-Moriya magnet and its manifestation in magnon-Skyrmion scattering,"We construct Holstein-Primakoff Hamiltonian for magnons in arbitrary slowly
+varying spin background, for a microscopic spin Hamiltonian consisting of
+ferromagnetic spin exchange,Dzyaloshinskii-Moriya exchange, and the Zeeman
+term. The Gross-Pitaevskii-type equation for magnon dynamics contains several
+background gauge fields pertaining to local spin chirality, inhomogeneous
+potential, and anomalous scattering that violates the boson number
+conservation. Non-trivial corrections to previous formulas derived in the
+literature are given. Subsequent mapping to hydrodynamic fields yields the
+continuity equation and the Euler equation of the magnon fluid dynamics. Magnon
+wave scattering off a localized Skyrmion is examined numerically based on our
+Gross-Pitaevskii formulation. Dependence of the effective flux experienced by
+the impinging magnon on the Skyrmion radius is pointed out, and compared with
+analysis of the same problem using the Landau-Lifshitz-Gilbert equation.",1501.06467v1
+2015-02-05,Improved efficiency of heat generation in nonlinear dynamics of magnetic nanoparticles,"The deterministic Landau-Lifshitz-Gilbert equation has been used to
+investigate the nonlinear dynamics of magnetization and the specific loss power
+in magnetic nanoparticles with uniaxial anisotropy driven by a rotating
+magnetic field. We propose a new type of applied field, which is
+""simultaneously rotating and alternating"", i.e. the direction of the rotating
+external field changes periodically. We show that a more efficient heat
+generation by magnetic nanoparticles is possible with this new type of applied
+field and we suggest its possible experimental realization in cancer therapy
+which requires the enhancement of loss energies.",1502.01619v2
+2015-03-10,Microwave-induced dynamic switching of magnetic skyrmion cores in nanodots,"The nonlinear dynamic behavior of a magnetic skyrmion in circular nanodots
+was studied numerically by solving the Landau-Lifshitz-Gilbert equation with a
+classical spin model. We show that a skyrmion core reversal can be achieved
+within nanoseconds using a perpendicular oscillating magnetic field. Two
+symmetric switching processes that correspond to excitations of the breathing
+mode and the mixed mode (combination of the breathing mode and a radial
+spin-wave mode) are identified. For excitation of the breathing mode, the
+skyrmion core switches through nucleation of a new core from a transient
+uniform state. In the mixed mode, the skyrmion core reverses with the help of
+spins excited both at the edge and core regions. Unlike the magnetic vortex
+core reversal, the excitation of radial spin waves does not dominate the
+skyrmion core reversal process.",1503.02869v1
+2015-03-23,Local dynamics of topological magnetic defects in the itinerant helimagnet FeGe,"Chiral magnetic interactions induce complex spin textures including helical
+and conical spin waves, as well as particle-like objects such as magnetic
+skyrmions and merons. These spin textures are the basis for innovative device
+paradigms and give rise to exotic topological phenomena, thus being of interest
+for both applied and fundamental sciences. Present key questions address the
+dynamics of the spin system and emergent topological defects. Here we analyze
+the micromagnetic dynamics in the helimagnetic phase of FeGe. By combining
+magnetic force microscopy, single-spin magnetometry, and
+Landau-Lifschitz-Gilbert simulations we show that the nanoscale dynamics are
+governed by the depinning and subsequent motion of magnetic edge dislocations.
+The motion of these topologically stable objects triggers perturbations that
+can propagate over mesoscopic length scales. The observation of stochastic
+instabilities in the micromagnetic structure provides new insight to the
+spatio-temporal dynamics of itinerant helimagnets and topological defects, and
+discloses novel challenges regarding their technological usage.",1503.06622v2
+2015-04-01,Minimum-cost matching in a random graph with random costs,"Let $G_{n,p}$ be the standard Erd\H{o}s-R\'enyi-Gilbert random graph and let
+$G_{n,n,p}$ be the random bipartite graph on $n+n$ vertices, where each $e\in
+[n]^2$ appears as an edge independently with probability $p$. For a graph
+$G=(V,E)$, suppose that each edge $e\in E$ is given an independent uniform
+exponential rate one cost. Let $C(G)$ denote the random variable equal to the
+length of the minimum cost perfect matching, assuming that $G$ contains at
+least one. We show that w.h.p. if $d=np\gg(\log n)^2$ then w.h.p. ${\bf
+E}[C(G_{n,n,p})] =(1+o(1))\frac{\p^2}{6p}$. This generalises the well-known
+result for the case $G=K_{n,n}$. We also show that w.h.p. ${\bf E}[C(G_{n,p})]
+=(1+o(1))\frac{\p^2}{12p}$ along with concentration results for both types of
+random graph.",1504.00312v5
+2015-04-04,"Graphs, Matrices, and the GraphBLAS: Seven Good Reasons","The analysis of graphs has become increasingly important to a wide range of
+applications. Graph analysis presents a number of unique challenges in the
+areas of (1) software complexity, (2) data complexity, (3) security, (4)
+mathematical complexity, (5) theoretical analysis, (6) serial performance, and
+(7) parallel performance. Implementing graph algorithms using matrix-based
+approaches provides a number of promising solutions to these challenges. The
+GraphBLAS standard (istc-bigdata.org/GraphBlas) is being developed to bring the
+potential of matrix based graph algorithms to the broadest possible audience.
+The GraphBLAS mathematically defines a core set of matrix-based graph
+operations that can be used to implement a wide class of graph algorithms in a
+wide range of programming environments. This paper provides an introduction to
+the GraphBLAS and describes how the GraphBLAS can be used to address many of
+the challenges associated with analysis of graphs.",1504.01039v2
+2015-04-08,A Global Star Forming Episode in M31 2-4 Gyr Ago,"We have identified a major global enhancement of star formation in the inner
+M31 disk that occurred between 2-4 Gyr ago, producing $\sim$60% of the stellar
+mass formed in the past 5 Gyr. The presence of this episode in the inner disk
+was discovered by modeling the optical resolved star color-magnitude diagrams
+of low extinction regions in the main disk of M31 (3$<$R$<$20 kpc) as part of
+the Panchromatic Hubble Andromeda Treasury. This measurement confirms and
+extends recent measurements of a widespread star formation enhancement of
+similar age in the outer disk, suggesting that this burst was both massive and
+global. Following the galaxy-wide burst, the star formation rate of M31 has
+significantly declined. We briefly discuss possible causes for these features
+of the M31 evolutionary history, including interactions with M32, M33 and/or a
+merger.",1504.02120v1
+2015-04-13,Ultra-low-energy non-volatile straintronic computing using single multiferroic composites,"The primary impediment to continued downscaling of traditional charge-based
+electronic devices in accordance with Moore's law is the excessive energy
+dissipation that takes place in the device during switching of bits. One very
+promising solution is to utilize multiferroic heterostructures, comprised of a
+single-domain magnetostrictive nanomagnet strain-coupled to a piezoelectric
+layer, in which the magnetization can be switched between its two stable states
+while dissipating minuscule amount of energy. However, no efficient and viable
+means of computing is proposed so far. Here we show that such single
+multiferroic composites can act as universal logic gates for computing
+purposes, which we demonstrate by solving the stochastic
+Landau-Lifshitz-Gilbert (LLG) equation of magnetization dynamics in the
+presence of room-temperature thermal fluctuations. The proposed concept can
+overwhelmingly simplify the design of large-scale circuits and portend a highly
+dense yet an ultra-low-energy computing paradigm for our future information
+processing systems.",1504.03907v1
+2015-04-20,"Electric field-induced magnetization switching in interface-coupled multiferroic heterostructures: A highly-dense, non-volatile, and ultra-low-energy computing paradigm","Electric-field induced magnetization switching in multiferroic
+magnetoelectric devices is promising for beyond Moore's law computing. We show
+here that interface-coupled multiferroic heterostructures, i.e., a
+ferroelectric layer coupled with a ferromagnetic layer, are particularly
+suitable for highly-dense, non-volatile, and ultra-low-energy computing. By
+solving stochastic Landau-Lifshitz-Gilbert equation of magnetization dynamics
+in the presence of room-temperature thermal fluctuations, we demonstrate that
+error-resilient switching of magnetization is possible in sub-nanosecond delay
+while expending a minuscule amount of energy of $\sim$1 attojoule. Such devices
+can be operated by drawing energy from the environment without the need for an
+external battery.",1504.05572v1
+2015-04-23,Quantum Magnets and Matrix Lorenz Systems,"The Landau--Lifshitz--Gilbert equations for the evolution of the
+magnetization, in presence of an external torque, can be cast in the form of
+the Lorenz equations and, thus, can describe chaotic fluctuations. To study
+quantum effects, we describe the magnetization by matrices, that take values in
+a Lie algebra. The finite dimensionality of the representation encodes the
+quantum fluctuations, while the non-linear nature of the equations can describe
+chaotic fluctuations. We identify a criterion, for the appearance of such
+non-linear terms. This depends on whether an invariant, symmetric tensor of the
+algebra can vanish or not. This proposal is studied in detail for the
+fundamental representation of
+$\mathfrak{u}(2)=\mathfrak{u}(1)\times\mathfrak{su}(2)$. We find a knotted
+structure for the attractor, a bimodal distribution for the largest Lyapunov
+exponent and that the dynamics takes place within the Cartan subalgebra, that
+does not contain only the identity matrix, thereby can describe the quantum
+fluctuations.",1504.06161v1
+2015-04-26,Speed of field driven domain walls in nanowires with large transverse magnetic anisotropy,"Recent analytical and numerical work on field driven domain wall propagation
+in nanowires has shown that for large transverse anisotropy and sufficiently
+large applied fields the Walker profile becomes unstable before the breakdown
+field, giving way to a slower stationary domain wall. We perform an asymptotic
+expansion of the Landau Lifshitz Gilbert equation for large transverse magnetic
+anisotropy and show that the asymptotic dynamics reproduces this behavior. At
+low applied field the speed increases linearly with the field and the profile
+is the classic Landau profile. Beyond a critical value of the applied field the
+domain wall slows down. The appearance of a slower domain wall profile in the
+asymptotic dynamics is due to a transition from a pushed to a pulled front of a
+reaction diffusion equation.",1504.06865v1
+2015-04-27,New Reversal Mode in Exchange Coupled Antiferromagnetic/Ferromagnetic Disks: Distorted Viscous Vortex,"Magnetic vortices have generated intense interest in recent years due to
+their unique reversal mechanisms, fascinating topological properties, and
+exciting potential applications. Additionally, the exchange coupling of
+magnetic vortices to antiferromagnets has also been shown to lead to a range of
+novel phenomena and functionalities. Here we report a new magnetization
+reversal mode of magnetic vortices in exchange coupled Ir20Mn80/Fe20Ni80
+microdots: distorted viscous vortex reversal. Contrary to the previously known
+or proposed reversal modes, the vortex is distorted close to the interface and
+viscously dragged due to the uncompensated spins of a thin antiferromagnet,
+which leads to unexpected asymmetries in the annihilation and nucleation
+fields. These results provide a deeper understanding of the physics of exchange
+coupled vortices and may also have important implications for applications
+involving exchange coupled nanostructures.",1504.07121v1
+2015-05-03,Driving magnetic skyrmions with microwave fields,"We show theoretically by numerically solving the Landau-Lifshitz-Gilbert
+equation with a classical spin model on a two-dimensional system that both
+magnetic skyrmions and skyrmion lattices can be moved with microwave magnetic
+fields. The mechanism is enabled by breaking the axial symmetry of the
+skyrmion, for example through application of a static in-plane external field.
+The net velocity of the skyrmion depends on the frequency and amplitude of the
+microwave fields as well as the strength of the in-plane field. The maximum
+velocity is found where the frequency of the microwave coincides with the
+resonance frequency of the breathing mode of the skyrmions.",1505.00445v2
+2015-05-04,Landau-Lifshitz theory of the thermomagnonic torque,"We derive the thermomagnonic torque associated with smooth magnetic textures
+subjected to a temperature gradient, in the framework of the stochastic
+Landau-Lifshitz-Gilbert equation. Our approach captures on equal footing two
+distinct contributions: (1) A local entropic torque that is caused by a
+temperature dependence of the effective exchange field, the existence of which
+had been previously suggested based on numerics and (2) the well-known
+spin-transfer torque induced by thermally-induced magnon flow. The dissipative
+components of two torques have the same structure, following a common
+phenomenology, but opposite signs, with the twice larger entropic torque
+leading to a domain-wall motion toward the hotter region. We compare the
+efficiency of the torque-driven domain-wall motion with the recently proposed
+Brownian thermophoresis.",1505.00818v1
+2015-05-05,Three-dimensional Character of the Magnetization Dynamics in Magnetic Vortex Structures - Hybridization of Flexure Gyromodes with Spin Waves,"Three-dimensional linear spin-wave eigenmodes of a Permalloy disk having
+finite thickness are studied by micromagnetic simulations based on the
+Landau-Lifshitz-Gilbert equation. The eigenmodes found in the simulations are
+interpreted as linear superpositions (hybridizations) of 'approximate'
+three-dimensional eigenmodes, which are the fundamental gyromode $G_0$, the
+spin-wave modes and the higher-order gyromodes $G_N$ (flexure modes), the
+thickness dependence of which is represented by perpendicular standing spin
+waves. This hybridization leads to new and surprising dependencies of the mode
+frequencies on the disk thickness. The three-dimensional character of the
+eigenmodes is essential to explain the recent experimental results on
+vortex-core reversal observed in relatively thick Permalloy disks.",1505.01148v2
+2015-05-14,A Subset Selection Algorithm for Wireless Sensor Networks,"One of the main challenges facing wireless sensor networks (WSNs) is the
+limited power resources available at small sensor nodes. It is therefore
+desired to reduce the power consumption of sensors while keeping the distortion
+between the source information and its estimate at the fusion centre (FC) below
+a specific threshold. In this paper, given the channel state information at the
+FC, we propose a subset selection algorithm of sensor nodes to reduce the
+average transmission power of the WSN. We assume the channels between the
+source and the sensors to be correlated fading channels, modeled by the
+Gilbert-Elliott model. We show that when these channels are known at the FC, a
+subset of sensors can be selected by the FC such that the received observations
+from this subset is sufficient to estimate the source information at the FC
+while maintaining the distortion between source information and its estimate
+below a specific threshold. Through analyses, we find the probability
+distribution of the size of this subset and provide results to evaluate the
+power efficiency of our proposed algorithm.",1505.03640v1
+2015-05-20,Effect of Transverse Magnetic Field on Dynamics of Current Driven Domain Wall Motion in the Presence of Spin-Hall Effect,"Theoretically, we study the dynamics of a current induced domain wall in the
+bi-layer structure consists of a ferromagnetic layer and a non-magnetic metal
+layer with strong spin-orbit coupling in the presence of spin-Hall effect. The
+analytical expressions for the velocity and width of the domain wall interms of
+excitation angle are obtained by solving the Landau-Lifshitz-Gilbert equation
+with adiabatic, nonadiabatic and spin Hall effect-spin transfer torques using
+Schryers and Walker's method. Numerical results show that the occurance of
+polarity switching in the domain wall is observed only above the threshold
+current density. The presence of transverse magnetic field along with spin Hall
+effect-spin transfer torque enchances the value of the threshold current
+density, and the corresponding saturated velocity at the threshold current
+density is also increased.",1505.05249v1
+2015-05-25,New Explicit Binary Constant Weight Codes from Reed-Solomon Codes,"Binary constant weight codes have important applications and have been
+studied for many years. Optimal or near-optimal binary constant weight codes of
+small lengths have been determined. In this paper we propose a new construction
+of explicit binary constant weight codes from $q$-ary Reed-Solomon codes. Some
+of our binary constant weight codes are optimal or new. In particular new
+binary constant weight codes $A(64, 10, 8) \geq 4108$ and $A(64, 12, 8) \geq
+522$ are constructed. We also give explicitly constructed binary constant
+weight codes which improve Gilbert and Graham-Sloane lower bounds in some range
+of parameters. An extension to algebraic geometric codes is also presented.",1505.06524v4
+2015-06-01,Closing the hierarchy for non-Markovian magnetization dynamics,"We propose a stochastic approach for the description of the time evolution of
+the magnetization of nanomagnets, that interpolates between the
+Landau--Lifshitz--Gilbert and the Landau--Lifshitz--Bloch approximations, by
+varying the strength of the noise. In addition, we take into account the
+autocorrelation time of the noise and explore the consequences, when it is
+finite, on the scale of the response of the magnetization, i.e. when it may be
+described as colored, rather than white, noise and non-Markovian features
+become relevant. We close the hierarchy for the moments of the magnetization,
+by introducing a suitable truncation scheme, whose validity is tested by direct
+numerical solution of the moment equations and compared to the average deduced
+from a numerical solution of the corresponding stochastic Langevin equation. In
+this way we establish a general framework, that allows both coarse-graining
+simulations and faster calculations beyond the truncation approximation used
+here.",1506.00544v1
+2015-06-02,Spin Superfluidity in the $ν=0$ Quantum Hall State of Graphene,"A proposal to detect the purported canted antiferromagnet order for the
+$\nu=0$ quantum Hall state of graphene based on a two-terminal spin transport
+setup is theoretically discussed. In the presence of a magnetic field normal to
+the graphene plane, a dynamic and inhomogeneous texture of the N\'eel vector
+lying within the plane should mediate (nearly dissipationless) superfluid
+transport of spin angular momentum polarized along the $z$ axis, which could
+serve as a strong support for the canted antiferromagnet scenario. Spin
+injection and detection can be achieved by coupling two spin-polarized edge
+channels of the $|\nu|=2$ quantum Hall state on two opposite ends of the
+$\nu=0$ region. A simple kinetic theory and Onsager reciprocity are invoked to
+model the spin injection and detection processes, and the transport of spin
+through the antiferromagnet is accounted for using the Landau-Lifshitz-Gilbert
+phenomenology.",1506.01061v1
+2015-06-05,Multi-reference approach to the calculation of photoelectron spectra including spin-orbit coupling,"X-ray photoelectron spectra provide a wealth of information on the electronic
+structure. The extraction of molecular details requires adequate theoretical
+methods, which in case of transition metal complexes has to account for effects
+due to the multi-configurational and spin-mixed nature of the many-electron
+wave function. Here, the Restricted Active Space Self-Consistent Field method
+including spin-orbit coupling is used to cope with this challenge and to
+calculate valence and core photoelectron spectra. The intensities are estimated
+within the frameworks of the Dyson orbital formalism and the sudden
+approximation. Thereby, we utilize an efficient computational algorithm that is
+based on a biorthonormal basis transformation. The approach is applied to the
+valence photoionization of the gas phase water molecule and to the core
+ionization spectrum of the $\text{[Fe(H}_2\text{O)}_6\text{]}^{2+}$ complex.
+The results show good agreement with the experimental data obtained in this
+work, whereas the sudden approximation demonstrates distinct deviations from
+experiments.",1506.01826v1
+2015-06-10,Parafermionic phases with symmetry-breaking and topological order,"Parafermions are the simplest generalizations of Majorana fermions that
+realize topological order. We propose a less restrictive notion of topological
+order in 1D open chains, which generalizes the seminal work by Fendley [J.
+Stat. Mech., P11020 (2012)]. The first essential property is that the
+groundstates are mutually indistinguishable by local, symmetric probes, and the
+second is a generalized notion of zero edge modes which cyclically permute the
+groundstates. These two properties are shown to be topologically robust, and
+applicable to a wider family of topologically-ordered Hamiltonians than has
+been previously considered. An an application of these edge modes, we formulate
+a new notion of twisted boundary conditions on a closed chain, which guarantees
+that the closed-chain groundstate is topological, i.e., it originates from the
+topological manifold of degenerate states on the open chain. Finally, we
+generalize these ideas to describe symmetry-breaking phases with a
+parafermionic order parameter. These exotic phases are condensates of
+parafermion multiplets, which generalizes Cooper pairing in superconductors.
+The stability of these condensates are investigated on both open and closed
+chains.",1506.03455v1
+2015-06-17,Magnetic field control of the spin Seebeck effect,"The origin of the suppression of the longitudinal spin Seebeck effect by
+applied magnetic fields is studied. We perform numerical simulations of the
+stochastic Landau-Lifshitz-Gilbert equation of motion for an atomistic spin
+model and calculate the magnon accumulation in linear temperature gradients for
+different strengths of applied magnetic fields and different length scales of
+the temperature gradient. We observe a decrease of the magnon accumulation with
+increasing magnetic field and we reveal that the origin of this effect is a
+field dependent change of the frequency distribution of the propagating
+magnons. With increasing field the magnonic spin currents are reduced due to a
+suppression of parts of the frequency spectrum. By comparison with measurements
+of the magnetic field dependent longitudinal spin Seebeck effect in YIG thin
+films with various thicknesses, we find that our model describes the
+experimental data very well, demonstrating the importance of this effect for
+experimental systems.",1506.05290v1
+2015-06-18,The pion quasiparticle in the low-temperature phase of QCD,"We investigate the properties of the pion quasiparticle in the
+low-temperature phase of two-flavor QCD on the lattice with support from chiral
+effective theory. We find that the pion quasiparticle mass is significantly
+reduced compared to its value in the vacuum, by contrast with the static
+screening mass, which increases with temperature. By a simple argument, near
+the chiral limit the two masses are expected to determine the quasiparticle
+dispersion relation. Analyzing two-point functions of the axial charge density
+at non-vanishing spatial momentum, we find that the predicted dispersion
+relation and the residue of the pion pole are simultaneously consistent with
+the lattice data at low momentum. The test, based on fits to the correlation
+functions, is confirmed by a second analysis using the Backus-Gilbert method.",1506.05732v1
+2015-06-23,Bounds on the Parameters of Locally Recoverable Codes,"A locally recoverable code (LRC code) is a code over a finite alphabet such
+that every symbol in the encoding is a function of a small number of other
+symbols that form a recovering set. In this paper we derive new finite-length
+and asymptotic bounds on the parameters of LRC codes. For LRC codes with a
+single recovering set for every coordinate, we derive an asymptotic
+Gilbert-Varshamov type bound for LRC codes and find the maximum attainable
+relative distance of asymptotically good LRC codes. Similar results are
+established for LRC codes with two disjoint recovering sets for every
+coordinate. For the case of multiple recovering sets we derive a lower bound on
+the parameters using expander graph arguments. Finally, we also derive
+finite-length upper bounds on the rate and distance of LRC codes with multiple
+recovering sets.",1506.07196v2
+2015-06-24,From Random Matrix Theory to Coding Theory: Volume of a Metric Ball in Unitary Group,"Volume estimates of metric balls in manifolds find diverse applications in
+information and coding theory. In this paper, some new results for the volume
+of a metric ball in unitary group are derived via various tools from random
+matrix theory. The first result is an integral representation of the exact
+volume, which involves a Toeplitz determinant of Bessel functions. The
+connection to matrix-variate hypergeometric functions and Szeg\H{o}'s strong
+limit theorem lead independently from the finite size formula to an asymptotic
+one. The convergence of the limiting formula is exceptionally fast due to an
+underlying mock-Gaussian behavior. The proposed volume estimate enables simple
+but accurate analytical evaluation of coding-theoretic bounds of unitary codes.
+In particular, the Gilbert-Varshamov lower bound and the Hamming upper bound on
+cardinality as well as the resulting bounds on code rate and minimum distance
+are derived. Moreover, bounds on the scaling law of code rate are found.
+Lastly, a closed-form bound on diversity sum relevant to unitary space-time
+codes is obtained, which was only computed numerically in literature.",1506.07259v1
+2015-06-18,Ultra-low-energy computing paradigm using giant spin Hall devices,"Spin Hall effect converts charge current to spin current, which can exert
+spin-torque to switch the magnetization of a nanomagnet. Recently, it is shown
+that the ratio of spin current to charge current using spin Hall effect can be
+made more than unity by using the areal geometry judiciously, unlike the case
+of conventional spin-transfer-torque switching of nanomagnets. This can enable
+energy-efficient means to write a bit of information in nanomagnets. Here, we
+study the energy dissipation in such spin Hall devices. By solving stochastic
+Landau-Lifshitz-Gilbert equation of magnetization dynamics in the presence of
+room temperature thermal fluctuations, we show a methodology to simultaneously
+reduce switching delay, its variance and energy dissipation, while lateral
+dimensions of the spin Hall devices are scaled down.",1506.07863v1
+2015-06-18,Separating read and write units in multiferroic devices,"Strain-mediated multiferroic composites, i.e., piezoelectric-magnetostrictive
+heterostructures, hold profound promise for energy-efficient computing in
+beyond Moore's law era. While reading a bit of information stored in the
+magnetostrictive nanomagnets using a magnetic tunnel junction (MTJ), a material
+selection issue crops up since magnetostrictive materials in general cannot be
+utilized as the free layer of the MTJ. This is an important issue since we need
+to achieve a high magnetoresistance for technological applications. We show
+here that magnetically coupling the magnetostrictive nanomagnet and the free
+layer e.g., utilizing the magnetic dipole coupling between them can circumvent
+this issue. By solving stochastic Landau-Lifshitz-Gilbert equation of
+magnetization dynamics in the presence of room-temperature thermal
+fluctuations, we show that such design can eventually lead to a superior
+energy-delay product.",1506.07865v1
+2015-06-26,Estimating the Parameters of the Waxman Random Graph,"The Waxman random graph is a generalisation of the simple Erd\H{o}s-R\'enyi
+or Gilbert random graph. It is useful for modelling physical networks where the
+increased cost of longer links means they are less likely to be built, and thus
+less numerous than shorter links. The model has been in continuous use for over
+two decades with many attempts to select parameters which match real networks.
+In most the parameters have been arbitrarily selected, but there are a few
+cases where they have been calculated using a formal estimator. However, the
+performance of the estimator was not evaluated in any of these cases. This
+paper presents both the first evaluation of formal estimators for the
+parameters of these graphs, and a new Maximum Likelihood Estimator with $O(n)$
+computational time complexity that requires only link lengths as input.",1506.07974v2
+2015-07-07,Rayleigh-Jeans condensation of pumped magnons in thin film ferromagnets,"We show that the formation of a magnon condensate in thin ferromagnetic films
+can be explained within the framework of a classical stochastic non-Markovian
+Landau-Lifshitz-Gilbert equation where the properties of the random magnetic
+field and the dissipation are determined by the underlying phonon dynamics. We
+have numerically solved this equation for a tangentially magnetized
+yttrium-iron garnet film in the presence of a parallel parametric pumping
+field. We obtain a complete description of all stages of the nonequilibrium
+time evolution of the magnon gas which is in excellent agreement with
+experiments. Our calculation proves that the experimentally observed
+condensation of magnons in yttrium-iron garnet at room temperature is a purely
+classical phenomenon which should be called Rayleigh-Jeans rather than
+Bose-Einstein condensation.",1507.01717v2
+2015-07-07,Dynamic Reallocation Problems in Scheduling,"In this paper we look at the problem of scheduling tasks on a
+single-processor system, where each task requires unit time and must be
+scheduled within a certain time window, and each task can be added to or
+removed from the system at any time. On each operation, the system is allowed
+to reschedule any tasks, but the goal is to minimize the number of rescheduled
+tasks. Our main result is an allocator that maintains a valid schedule for all
+tasks in the system if their time windows have constant size and reschedules
+O(1/{\epsilon}*log(1/{\epsilon})) tasks on each insertion as {\epsilon}->0,
+where {\epsilon} is a certain measure of the schedule flexibility of the
+system. We also show that it is optimal for any allocator that works on
+arbitrary instances. We also briefly mention a few variants of the problem,
+such as if the tasks have time windows of difference sizes, for which we have
+an allocator that we conjecture reschedules only 1 task on each insertion if
+the schedule flexibility remains above a certain threshold.",1507.01981v2
+2015-08-03,Stable oscillation in spin torque oscillator excited by a small in-plane magnetic field,"Theoretical conditions to excite self-oscillation in a spin torque oscillator
+consisting of a perpendicularly magnetized free layer and an in-plane
+magnetized pinned layer are investigated by analytically solving the
+Landau-Lifshitz-Gilbert equation. The analytical relation between the current
+and oscillation frequency is derived. It is found that a large amplitude
+oscillation can be excited by applying a small field pointing to the direction
+anti-parallel to the magnetization of the pinned layer. The validity of the
+analytical results is confirmed by comparing with numerical simulation, showing
+good agreement especially in a low current region.",1508.00601v1
+2015-08-07,Spin Dynamics in Driven Composite Multiferroics,"A spin dynamics approach has been used to study the behavior of the magnetic
+spins and the electric pseudo-spins in a 1-D composite multiferroic chain with
+a linear magneto-electric coupling at the interface. The response is
+investigated with either external magnetic or electric fields driving the
+system. The spin dynamics is based on the Landau-Lifshitz-Gilbert equation. A
+Gaussian white noise is later added into the dynamic process to include the
+thermal effects. The interface requires a closer inspection of the
+magneto-electric effects. Thus, we construct a 2-D ladder model to describe the
+behavior of the magnetic spins and the electric pseudo-spins with different
+magneto-electric couplings.",1508.01584v2
+2015-08-11,Analysis of a coupled spin drift-diffusion Maxwell-Landau-Lifshitz system,"The existence of global weak solutions to a coupled spin drift-diffusion and
+Maxwell-Landau-Lifshitz system is proved. The equations are considered in a
+two-dimensional magnetic layer structure and are supplemented with
+Dirichlet-Neumann boundary conditions. The spin drift-diffusion model for the
+charge density and spin density vector is the diffusion limit of a spinorial
+Boltzmann equation for a vanishing spin polarization constant. The
+Maxwell-Landau-Lifshitz system consists of the time-dependent Maxwell equations
+for the electric and magnetic fields and of the Landau-Lifshitz-Gilbert
+equation for the local magnetization, involving the interaction between
+magnetization and spin density vector. The existence proof is based on a
+regularization procedure, $L^2$-type estimates, and Moser-type iterations which
+yield the boundedness of the charge and spin densities. Furthermore, the free
+energy is shown to be nonincreasing in time if the magnetization-spin
+interaction constant in the Landau-Lifshitz equation is sufficiently small.",1508.02660v1
+2015-08-12,Bounds for codes on pentagon and other cycles,"The capacity of a graph is defined as the rate of exponential grow of
+independent sets in the strong powers of the graph. In strong power, an edge
+connects two sequences if at each position letters are equal or adjacent. We
+consider a variation of the problem where edges in the power graphs are removed
+among sequences which differ in more than a fraction $\delta$ of coordinates.
+For odd cycles, we derive an upper bound on the corresponding rate which
+combines Lov\'asz' bound on the capacity with Delsarte's linear programming
+bounds on the minimum distance of codes in Hamming spaces. For the pentagon,
+this shows that for $\delta \ge {1-{1\over\sqrt{5}}}$ the Lov\'asz rate is the
+best possible, while we prove by a Gilbert-Varshamov-type bound that a higher
+rate is achievable for $\delta < {2\over 5}$.
+  Communication interpretation of this question is the problem of sending
+quinary symbols subject to $\pm 1\mod 5$ disturbance. The maximal communication
+rate subject to the zero undetected-error equals capacity of a pentagon. The
+question addressed here is how much this rate can be increased if only a
+fraction $\delta$ of symbols is allowed to be disturbed",1508.03020v1
+2015-08-14,Smoothed Analysis of Dynamic Networks,"We generalize the technique of smoothed analysis to distributed algorithms in
+dynamic network models. Whereas standard smoothed analysis studies the impact
+of small random perturbations of input values on algorithm performance metrics,
+dynamic graph smoothed analysis studies the impact of random perturbations of
+the underlying changing network graph topologies. Similar to the original
+application of smoothed analysis, our goal is to study whether known strong
+lower bounds in dynamic network models are robust or fragile: do they withstand
+small (random) perturbations, or do such deviations push the graphs far enough
+from a precise pathological instance to enable much better performance? Fragile
+lower bounds are likely not relevant for real-world deployment, while robust
+lower bounds represent a true difficulty caused by dynamic behavior. We apply
+this technique to three standard dynamic network problems with known strong
+worst-case lower bounds: random walks, flooding, and aggregation. We prove that
+these bounds provide a spectrum of robustness when subjected to
+smoothing---some are extremely fragile (random walks), some are moderately
+fragile / robust (flooding), and some are extremely robust (aggregation).",1508.03579v1
+2015-08-16,The Computational Power of Beeps,"In this paper, we study the quantity of computational resources (state
+machine states and/or probabilistic transition precision) needed to solve
+specific problems in a single hop network where nodes communicate using only
+beeps. We begin by focusing on randomized leader election. We prove a lower
+bound on the states required to solve this problem with a given error bound,
+probability precision, and (when relevant) network size lower bound. We then
+show the bound tight with a matching upper bound. Noting that our optimal upper
+bound is slow, we describe two faster algorithms that trade some state
+optimality to gain efficiency. We then turn our attention to more general
+classes of problems by proving that once you have enough states to solve leader
+election with a given error bound, you have (within constant factors) enough
+states to simulate correctly, with this same error bound, a logspace TM with a
+constant number of unary input tapes: allowing you to solve a large and
+expressive set of problems. These results identify a key simplicity threshold
+beyond which useful distributed computation is possible in the beeping model.",1508.03859v1
+2015-09-02,Topological dynamics and current-induced motion in a skyrmion lattice,"We study the Thiele equation for current-induced motion in a skyrmion lattice
+through two soluble models of the pinning potential. Comprised by a Magnus
+term, a dissipative term and a pinning force, Thiele's equation resembles
+Newton's law but in virtue of the topological character of the first two, it
+differs significantly from Newtonian mechanics and because the Magnus force is
+dominant, unlike its mechanical counterpart, the Coriolis force, skyrmion
+trajectories do not necessarily have mechanical counterparts. This is important
+if we are to understand skykrmion dynamics and tap into its potential for
+data-storage technology. We identify a pinning threshold velocity for the
+one-dimensional potential and for a two-dimensional potential we find a pinning
+point and the skyrmion trajectories toward the point are spirals whose
+frequency (compare Kepler's second law) and amplitude decay depends only on the
+Gilbert constant and potential at the pinning point.",1509.00591v1
+2015-09-02,Thermally-Activated Phase Slips in Superfluid Spin Transport in Magnetic Wires,"We theoretically study thermally-activated phase slips in superfluid spin
+transport in easy-plane magnetic wires within the stochastic
+Landau-Lifshitz-Gilbert phenomenology, which runs parallel to the
+Langer-Ambegaokar-McCumber-Halperin theory for thermal resistances in
+superconducting wires. To that end, we start by obtaining the exact solutions
+for free-energy minima and saddle points. We provide an analytical expression
+for the phase-slip rate in the zero spin-current limit, which involves detailed
+analysis of spin fluctuations at extrema of the free energy. An experimental
+setup of a magnetoeletric circuit is proposed, in which thermal phase slips can
+be inferred by measuring nonlocal magnetoresistance.",1509.00904v1
+2015-09-11,Comparison between a quantum kinetic theory of spin transfer dynamics in Mn doped bulk semiconductors and its Markov limit for non-zero Mn magnetization,"We investigate the transfer between carrier and Mn spins due to the
+s-d-exchange interaction in a Mn doped bulk semiconductor within a microscopic
+quantum kinetic theory. We demonstrate that the spin transfer dynamics is
+qualitatively different for components of the carrier spin parallel and
+perpendicular to the Mn magnetization. From our quantum kinetic equations we
+have worked out the corresponding Markov limit which is equivalent to rate
+equations based on Fermi's golden rule. The resulting equations resemble the
+widely used Landau-Lifshitz-Gilbert-equations, but also describe genuine spin
+transfer due to quantum corrections. Although it is known that the Markovian
+rate description works well for bulk systems when the initial Mn magnetization
+is zero, we find large qualitative deviations from the full quantum kinetic
+theory for finite initial Mn magnetizations. These deviations mainly reflect
+corrections of higher than leading order in the interaction which are not
+accounted for in golden rule-type rates.",1509.03479v1
+2015-09-14,Spectral characteristics of time resolved magnonic spin Seebeck effect,"Spin Seebeck effect (SSE) holds promise for new spintronic devices with
+low-energy consumption. The underlying physics, essential for a further
+progress, is yet to be fully clarified. This study of the time resolved
+longitudinal SSE in the magnetic insulator yttrium iron garnet (YIG) concludes
+that a substantial contribution to the spin current stems from small
+wave-vector subthermal exchange magnons. Our finding is in line with the recent
+experiment by S. R. Boona and J. P. Heremans, Phys. Rev. B 90, 064421 (2014).
+Technically, the spin-current dynamics is treated based on the
+Landau-Lifshitz-Gilbert (LLG) equation also including magnons back-action on
+thermal bath, while the formation of the time dependent thermal gradient is
+described self-consistently via the heat equation coupled to the magnetization
+dynamics",1509.04018v1
+2015-09-21,The pion quasiparticle in the low-temperature phase of QCD,"We investigate the properties of the pion quasiparticle in the
+low-temperature phase of two-flavor QCD on the lattice with support from chiral
+effective theory. We find that the pion quasiparticle mass is significantly
+reduced compared to its value in the vacuum, in contrast to the static
+screening mass, which increases with temperature. By a simple argument, the two
+masses are expected to determine the quasiparticle dispersion relation near the
+chiral limit. Analyzing two-point functions of the axial charge density at
+non-vanishing spatial momentum, we find that the predicted dispersion relation
+and the residue of the pion pole are simultaneously consistent with the lattice
+data at low momentum. The test, based on fits to the correlation functions, is
+confirmed by a second analysis using the Backus-Gilbert method.",1509.06241v1
+2015-10-29,On Differentially Private Online Collaborative Recommendation Systems,"In collaborative recommendation systems, privacy may be compromised, as
+users' opinions are used to generate recommendations for others. In this paper,
+we consider an online collaborative recommendation system, and we measure
+users' privacy in terms of the standard differential privacy. We give the first
+quantitative analysis of the trade-offs between recommendation quality and
+users' privacy in such a system by showing a lower bound on the best achievable
+privacy for any non-trivial algorithm, and proposing a near-optimal algorithm.
+From our results, we find that there is actually little trade-off between
+recommendation quality and privacy for any non-trivial algorithm. Our results
+also identify the key parameters that determine the best achievable privacy.",1510.08546v1
+2015-11-05,Non-Markovian magnetization dynamics for uniaxial nanomagnets,"A stochastic approach for the description of the time evolution of the
+magnetization of nanomagnets is proposed, that interpolates between the
+Landau-Lifshitz-Gilbert and the Landau-Lifshitz-Bloch approximations, by
+varying the strength of the noise. Its finite autocorrelation time, i.e. when
+it may be described as colored, rather than white, is, also, taken into account
+and the consequences, on the scale of the response of the magnetization are
+investigated. It is shown that the hierarchy for the moments of the
+magnetization can be closed, by introducing a suitable truncation scheme, whose
+validity is tested by direct numerical solution of the moment equations and
+compared to the averages obtained from a numerical solution of the
+corresponding colored stochastic Langevin equation. This comparison is
+performed on magnetic systems subject to both an external uniform magnetic
+field and an internal one-site uniaxial anisotropy.",1511.01693v1
+2015-11-06,Colored-noise magnetization dynamics: from weakly to strongly correlated noise,"Statistical averaging theorems allow us to derive a set of equations for the
+averaged magnetization dynamics in the presence of colored (non-Markovian)
+noise. The non-Markovian character of the noise is described by a finite
+auto-correlation time, tau, that can be identified with the finite response
+time of the thermal bath to the system of interest. Hitherto, this model was
+only tested for the case of weakly correlated noise (when tau is equivalent or
+smaller than the integration timestep). In order to probe its validity for a
+broader range of auto-correlation times, a non-Markovian integration model,
+based on the stochastic Landau-Lifshitz-Gilbert equation is presented.
+Comparisons between the two models are discussed, and these provide evidence
+that both formalisms remain equivalent, even for strongly correlated noise
+(i.e. tau much larger than the integration timestep).",1511.02008v1
+2015-12-17,A self-consistent spin-diffusion model for micromagnetics,"We propose a three-dimensional micromagnetic model that dynamically solves
+the Landau-Lifshitz-Gilbert equation coupled to the full spin-diffusion
+equation. In contrast to previous methods, we solve for the magnetization
+dynamics and the electric potential in a self-consistent fashion. This
+treatment allows for an accurate description of magnetization dependent
+resistance changes. Moreover, the presented algorithm describes both spin
+accumulation due to smooth magnetization transitions and due to material
+interfaces as in multilayer structures. The model and its finite-element
+implementation are validated by current driven motion of a magnetic vortex
+structure. In a second experiment, the resistivity of a magnetic multilayer
+structure in dependence of the tilting angle of the magnetization in the
+different layers is investigated. Both examples show good agreement with
+reference simulations and experiments respectively.",1512.05519v4
+2015-12-17,Statics and field-driven dynamics of transverse domain walls in biaxial nanowires under uniform transverse magnetic fields,"In this work, we report analytical results on transverse domain wall (TDW)
+statics and field-driven dynamics in quasi one-dimensional biaxial nanowires
+under arbitrary uniform transverse magnetic fields (TMFs) based on the
+Landau-Lifshitz-Gilbert equation. Without axial driving fields, the static TDW
+should be symmetric about its center meanwhile twisted in its azimuthal angle
+distribution. By decoupling of polar and azimuthal degrees of freedom, an
+approximate solution is provided which reproduces these features to a great
+extent. When an axial driving field is applied, the dynamical behavior of a TDW
+is viewed as the response of its static profile to external excitations. By
+means of the asymptotic expansion method, the TDW velocity in traveling-wave
+mode is obtained, which provides the extent and boundary of the
+""velocity-enhancement"" effect of TMFs to TDWs in biaxial nanowires. Finally
+numerical simulations are performed and strongly support our analytics.",1512.05627v2
+2015-12-24,Eroding dipoles and vorticity growth for Euler flows in $ \scriptstyle{\mathbb{R}}^3$ I. Axisymmetric flow without swirl,"A review of analyses based upon anti-parallel vortex structures suggests that
+structurally stable vortex structures with eroding circulation may offer a path
+to the study of rapid vorticity growth in solutions of Euler's equations in $
+\scriptstyle{\mathbb{R}}^3$. We examine here the possible formation of such a
+structure in axisymmetric flow without swirl, leading to maximal growth of
+vorticity as $t^{4/3}$. Our study suggests that the optimizing flow giving the
+$t^{4/3}$ growth mimics an exact solution of Euler's equations representing an
+eroding toroidal vortex dipole which locally conserves kinetic energy. The
+dipole cross-section is a perturbation of the classical Sadovskii dipole having
+piecewise constant vorticity, which breaks the symmetry of closed streamlines.
+The structure of this perturbed Sadovskii dipole is analyzed asymptotically at
+large times, and its predicted properties are verified numerically.",1512.07898v1
+2016-01-11,Reliable spin-transfer torque driven precessional magnetization reversal with an adiabatically decaying pulse,"We show that a slowly decaying current pulse can lead to nearly deterministic
+precessional switching in the presence of noise. We consider a biaxial
+macrospin, with an easy axis in the plane and a hard axis out-of-the plane,
+typical of thin film nanomagnets patterned into asymmetric shapes. Out-of-plane
+precessional magnetization orbits are excited with a current pulse with a
+component of spin polarization normal to the film plane. By numerically
+integrating the stochastic Landau-Lifshitz-Gilbert-Slonczewski equation we show
+that thermal noise leads to strong dephasing of the magnetization orbits.
+However, an adiabatically decreasing pulse amplitude overwhelmingly leads to
+magnetization reversal, with a final state that {\em only} depends on the pulse
+polarity, not on the pulse amplitude. We develop an analytic model to explain
+this phenomena and to determine the pulse decay time necessary for adiabatic
+magnetization relaxation and thus precessional magnetization switching.",1601.02336v1
+2016-01-19,Minimal Radius of Magnetic Skyrmions: Statics and Dynamics,"In a broad range of applied magnetic fields and material parameters isolated
+magnetic skyrmions condense into skyrmion lattices. While the geometry of
+isolated skyrmions and their lattice counterparts strongly depend on field and
+Dzyaloshinski-Moriya interaction, this issue has not been adequately addressed
+in previous studies. Meanwhile, this information is extremely important for
+applications, because the skyrmion size and the interskyrmion distance have to
+be tuned for skyrmion based memory and logic devices. In this investigation we
+elucidate the size and density-dependent phase diagram showing traditional
+phases in field vs. material parameters space by means of Monte-Carlo
+simulations on a discrete lattice. The obtained diagram permits us to establish
+that, in contrast to the continuum limit, skyrmions on a discrete lattice
+cannot be smaller than some critical size and have a very specific shape. These
+minimal skyrmions correspond to the micromagnetic configuration at the energy
+barrier between the ferromagnetic and the skyrmionic states. Furthermore, we
+use atomistic Landau-Lifshitz-Gilbert simulations to study dynamics of the
+skyrmion annihilation. It is shown that this procees consists of two stages:
+the continuous skyrmion contraction and its discontinuous annihilation. The
+detailed analysis of this dynamical process is given.",1601.04898v1
+2016-01-20,Limited-Magnitude Error-Correcting Gray Codes for Rank Modulation,"We construct Gray codes over permutations for the rank-modulation scheme,
+which are also capable of correcting errors under the infinity-metric. These
+errors model limited-magnitude or spike errors, for which only
+single-error-detecting Gray codes are currently known. Surprisingly, the
+error-correcting codes we construct achieve a better asymptotic rate than that
+of presently known constructions not having the Gray property, and exceed the
+Gilbert-Varshamov bound. Additionally, we present efficient ranking and
+unranking procedures, as well as a decoding procedure that runs in linear time.
+Finally, we also apply our methods to solve an outstanding issue with
+error-detecting rank-modulation Gray codes (snake-in-the-box codes) under a
+different metric, the Kendall $\tau$-metric, in the group of permutations over
+an even number of elements $S_{2n}$, where we provide asymptotically optimal
+codes.",1601.05218v3
+2016-01-20,Many-body effects on graphene conductivity: Quantum Monte Carlo calculations,"Optical conductivity of graphene is studied using Quantum Monte Carlo
+calculations. We start from Euclidean current-current correlator and extract
+$\sigma (\omega)$ from Green-Kubo relations using Backus-Gilbert method.
+Calculations were performed both for long-range interactions and taking into
+account only contact term. In both cases we vary interaction strength and study
+its influence on optical conductivity. We compare our results with previous
+theoretical calculations choosing $\omega \approx \kappa$ thus working in the
+region of the plateau in $\sigma(\omega)$ which corresponds to optical
+conductivity of Dirac quasiparticles. No dependence of optical conductivity on
+interaction strength is observed unless we approach antiferromagnetic phase
+transition in case of artificially enhanced contact term. Our results strongly
+support previous theoretical studies claimed very weak regularization of
+graphene conductivity.",1601.05315v2
+2016-02-01,Efficient thermal energy harvesting using nanoscale magnetoelectric heterostructures,"Thermomechanical cycles with a ferroelectric working substance convert heat
+to electrical energy. As shown here, magnetoelectrically coupled
+ferroelectric/ferromangtic composites (also called multiferroics) add new
+functionalities and allow for an efficient thermal energy harvesting at room
+temperature by exploiting the pyroelectric effect. By virtue of the
+magnetoelectric coupling, external electric and magnetic fields can steer the
+operation of these heat engines. Our theoretical predictions are based on a
+combination of Landau-Khalatnikov-Tani approach (with a
+Ginzburg-Landau-Devonshire potential) to simulate the ferroelectric dynamics
+coupled to the magnetic dynamics. The latter is treated via the
+electric-polarization-dependent Landau-Lifshitz-Gilbert equation. Performing an
+adapted Olsen cycle we show that a multiferroic working substance is
+potentially much more superior to sole ferroelectrics, as far as thermal energy
+harvesting using pyroelectric effect is concerned. Our proposal holds promise
+not only for low-energy consuming devices but also for cooling technology.",1602.00433v1
+2016-02-04,A double oracle approach for minmax regret optimization problems with interval data,"In this paper, we provide a generic anytime lower bounding procedure for
+minmax regret optimization problems. We show that the lower bound obtained is
+always at least as accurate as the lower bound recently proposed by Chassein
+and Goerigk (2015). This lower bound can be viewed as the optimal value of a
+linear programming relaxation of a mixed integer programming formulation of
+minmax regret optimization, but the contribution of the paper is to compute
+this lower bound via a double oracle algorithm (McMahan et al., 2003) that we
+specify. The double oracle algorithm is designed by relying on a game theoretic
+view of robust optimization, similar to the one developed by Mastin et al.
+(2015), and it can be efficiently implemented for any minmax regret
+optimization problem whose standard version is ""easy"". We describe how to
+efficiently embed this lower bound in a branch and bound procedure. Finally, we
+apply our approach to the robust shortest path problem. Our numerical results
+show a significant gain in the computation times compared to previous
+approaches in the literature.",1602.01764v3
+2016-02-10,Temperature dependence of the threshold magnetic field for nucleation and domain wall propagation in an inhomogeneous structure with grain boundary,"In order to study the dependence of the coercive force of sintered magnets on
+temperature, nucleation and domain wall propagation at the grain boundary are
+studied as rate-determining processes of the magnetization reversal phenomena
+in magnets consisting of bulk hard magnetic grains contacting via grain
+boundaries of a soft magnetic material. These systems have been studied
+analytically for a continuum model at zero temperature (A. Sakuma, et al. J.
+Mag. Mag. Mat. {\bf 84} 52 (1990)). In the present study, the temperature
+dependence is studied by making use of the stochastic Landau-Lifshitz-Gilbert
+equation at finite temperatures. In particular, the threshold fields for
+nucleation and domain wall propagation are obtained as functions of ratios of
+magnetic interactions and anisotropies of the soft and hard magnets for various
+temperatures. It was found that the threshold field for domain wall propagation
+is robust against thermal fluctuations, while that for nucleation is fragile.
+The microscopic mechanisms of the observed temperature dependence are
+discussed.",1602.03285v2
+2016-02-26,The magnetic monopole and the separation between fast and slow magnetic degrees of freedom,"The Landau-Lifshitz-Gilbert (LLG) equation that describes the dynamics of a
+macroscopic magnetic moment finds its limit of validity at very short times.
+The reason for this limit is well understood in terms of separation of the
+characteristic time scales between slow degrees of freedom (the magnetization)
+and fast degrees of freedom. The fast degrees of freedom are introduced as the
+variation of the angular momentum responsible for the inertia. In order to
+study the effect of the fast degrees of freedom on the precession, we calculate
+the geometric phase of the magnetization (i.e. the Hannay angle) and the
+corresponding magnetic monopole. In the case of the pure precession (the slow
+manifold), a simple expression of the magnetic monopole is given as a function
+of the slowness parameter, i.e. as a function of the ratio of the slow over the
+fast characteristic times.",1602.08470v1
+2016-03-01,Instability analysis of spin torque oscillator with an in-plane magnetized free layer and a perpendicularly magnetized pinned layer,"We study the theoretical conditions to excite a stable self-oscillation in a
+spin torque oscillator with an in-plane magnetized free layer and a
+perpendicularly magnetized pinned layer in the presence of magnetic field
+pointing in an arbitrary direction. The linearized Landau-Lifshitz-Gilbert
+(LLG) equation is found to be inapplicable to evaluate the threshold between
+the stable and self-oscillation states because the critical current density
+estimated from the linearized equation is considerably larger than that found
+in the numerical simulation. We derive a theoretical formula of the threshold
+current density by focusing on the energy gain of the magnetization from the
+spin torque during a time shorter than a precession period. A good agreement
+between the derived formula and the numerical simulation is obtained. The
+condition to stabilize the out-of-plane self-oscillation above the threshold is
+also discussed.",1603.00155v2
+2016-03-02,Electric-Field-Induced Spin Resonance in Antiferromagnetic Insulators: Inverse Process of the Dynamical Chiral Magnetic Effect,"We propose a realization of the electric-field-induced antiferromagnetic
+resonance. We consider three-dimensional antiferromagnetic insulators with
+spin-orbit coupling characterized by the existence of a topological term called
+the $\theta$ term. By solving the Landau-Lifshitz-Gilbert equation in the
+presence of the $\theta$ term, we show that, in contrast to conventional
+methods using ac magnetic fields, the antiferromagnetic resonance state is
+realized by ac electric fields along with static magnetic fields. This
+mechanism can be understood as the inverse process of the dynamical chiral
+magnetic effect, an alternating current generation by magnetic fields. In other
+words, we propose a way to electrically induce the dynamical axion field in
+condensed matter. We discuss a possible experiment to observe our proposal,
+which utilizes the spin pumping from the antiferromagnetic insulator into a
+heavy metal contact.",1603.00614v3
+2016-03-25,Microscopic theory of spin-orbit torques and skyrmion dynamics,"We formulate a general microscopic approach to spin-orbit torques in thin
+ferromagnet/heavy-metal bilayers in linear response to electric current or
+electric field. The microscopic theory we develop avoids the notion of spin
+currents and spin-Hall effect. Instead, the torques are directly related to a
+local spin polarization of conduction electrons, which is computed from
+generalized Kubo-St\v{r}eda formulas. A symmetry analysis provides a one-to-one
+correspondence between polarization susceptibility tensor components and
+different torque terms in the Landau-Lifshitz-Gilbert equation for
+magnetization dynamics. The spin-orbit torques arising from Rashba or
+Dresselhaus type of spin-orbit interaction are shown to have different
+symmetries. We analyze these spin-orbit torques microscopically for a generic
+electron model in the presence of an arbitrary smooth magnetic texture. For a
+model with spin-independent disorder we find a major cancelation of the
+torques. In this case the only remaining torque corresponds to the
+magnetization-independent Edelstein effect. Furthermore, our results are
+applied to analyze the dynamics of a Skyrmion under the action of electric
+current.",1603.07994v2
+2016-04-01,Modular Anomalies in (2+1) and (3+1)-D Edge Theories,"The classification of topological phases of matter in the presence of
+interactions is an area of intense interest. One possible means of
+classification is via studying the partition function under modular transforms,
+as the presence of an anomalous phase arising in the edge theory of a
+D-dimensional system under modular transformation, or modular anomaly, signals
+the presence of a (D+1)-D non-trivial bulk. In this work, we discuss the
+modular transformations of conformal field theories along a (2+1)-D and a
+(3+1)-D edge. Using both analytical and numerical methods, we show that chiral
+complex free fermions in (2+1)-D and (3+1)-D are modular invariant. However, we
+show in (3+1)-D that when the edge theory is coupled to a background U(1) gauge
+field this results in the presence of a modular anomaly that is the
+manifestation of a quantum Hall effect in a (4+1)-D bulk. Using the modular
+anomaly, we find that the edge theory of (4+1)-D insulator with spacetime
+inversion symmetry(P*T) and fermion number parity symmetry for each spin
+becomes modular invariant when 8 copies of the edges exist.",1604.00407v1
+2016-04-12,Voltage-driven magnetization switching and spin pumping in Weyl semimetals,"We demonstrate electrical magnetization switching and spin pumping in
+magnetically doped Weyl semimetals. The Weyl semimetal is a new class of
+topological semimetals, known to have nontrivial coupling between the charge
+and the magnetization due to the chiral anomaly. By solving the
+Landau-Lifshitz-Gilbert equation for a multilayer structure of a Weyl
+semimetal, an insulator and a metal whilst taking the charge-magnetization
+coupling into account, magnetization dynamics is analyzed. It is shown that the
+magnetization dynamics can be driven by the electric voltage. Consequently,
+switching of the magnetization with a pulsed electric voltage can be achieved,
+as well as precession motion with an applied oscillating electric voltage. The
+effect requires only a short voltage pulse and may therefore be more
+energetically efficient for us in spintronics devices compared to conventional
+spin transfer torque switching.",1604.03326v1
+2016-04-29,Current induced magnetization dynamics and magnetization switching in superconducting ferromagnetic hybrid (F$|$S$|$F) structures,"We investigate the current induced magnetization dynamics and magnetization
+switching in an unconventional p-wave superconductor sandwiched between two
+misaligned ferromagnetic layers by numerically solving Landau-Lifshitz-Gilbert
+equation modified with current induced Slonczewski's spin torque term. A
+modified form of Ginzburg-Landau free energy functional has been used for this
+purpose. We demonstrated the possibility of current induced magnetization
+switching in the spin-triplet ferromagnetic superconducting hybrid structures
+with strong easy axis anisotropy and the condition for magnetization reversal.
+The switching time for such arrangement is calculated and is found to be highly
+dependent on the magnetic configuration along with the biasing current. This
+study would be useful in designing practical superconducting-spintronic
+devices.",1604.08704v3
+2016-05-04,Asymptotic behaviors of Landau-Lifshitz flows from $\Bbb R^2$ to Kähler manifolds,"In this paper, we study the asymptotic behaviors of finite energy solutions
+to the Landau-Lifshitz flows from $\Bbb R^2$ into K\""ahler manifolds. First, we
+prove that the solution with initial data below the critical energy converges
+to a constant map in the energy space as $t\to \infty$ for the compact
+Riemannian surface targets. In particular, when the target is a two dimensional
+sphere, we prove that the solution to the Landau-Lifshitz-Gilbert equation with
+initial data having an energy below $4\pi$ converges to some constant map in
+the energy space. Second, for general compact K\""ahler manifolds and initial
+data of an arbitrary finite energy, we obtain a bubbling theorem analogous to
+the Struwe's results on the heat flows.",1605.01245v2
+2016-05-04,Phase transition and uniqueness of levelset percolation,"The main purpose of this paper is to introduce and establish basic results of
+a natural extension of the classical Boolean percolation model (also known as
+the Gilbert disc model). We replace the balls of that model by a positive
+non-increasing attenuation function $l:(0,\infty) \to (0,\infty)$ to create the
+random field $\Psi(y)=\sum_{x\in \eta}l(|x-y|),$ where $\eta$ is a homogeneous
+Poisson process in ${\mathbb R}^d.$ The field $\Psi$ is then a random potential
+field with infinite range dependencies whenever the support of the function $l$
+is unbounded.
+  In particular, we study the level sets $\Psi_{\geq h}(y)$ containing the
+points $y\in {\mathbb R}^d$ such that $\Psi(y)\geq h.$ In the case where $l$
+has unbounded support, we give, for any $d\geq 2,$ exact conditions on $l$ for
+$\Psi_{\geq h}(y)$ to have a percolative phase transition as a function of $h.$
+  We also prove that when $l$ is continuous then so is $\Psi$ almost surely.
+Moreover, in this case and for $d=2,$ we prove uniqueness of the infinite
+component of $\Psi_{\geq h}$ when such exists, and we also show that the
+so-called percolation function is continuous below the critical value $h_c$.",1605.01275v1
+2016-06-21,A stochastic model of supercoiling-dependent transcription,"We propose a stochastic model for gene transcription coupled to DNA
+supercoiling, where we incorporate the experimental observation that
+polymerases create supercoiling as they unwind the DNA helix, and that these
+enzymes bind more favourably to regions where the genome is unwound. Within
+this model, we show that when the transcriptionally induced flux of
+supercoiling increases, there is a sharp crossover from a regime where
+torsional stresses relax quickly and gene transcription is random, to one where
+gene expression is highly correlated and tightly regulated by supercoiling. In
+the latter regime, the model displays transcriptional bursts, waves of
+supercoiling, and up-regulation of divergent or bidirectional genes. It also
+predicts that topological enzymes which relax twist and writhe should provide a
+pathway to down-regulate transcription. This article has been published in
+Physical Review Letters, May 2016.",1606.06555v3
+2016-06-22,Induced magnetization and power loss for a periodically driven system of ferromagnetic nanoparticles with randomly oriented easy axes,"We study the effect of an elliptically polarized magnetic field on a system
+of non-interacting, single-domain ferromagnetic nanoparticles characterized by
+a uniform distribution of easy axis directions. Our main goal is to determine
+the average magnetization of this system and the power loss in it. In order to
+calculate these quantities analytically, we develop a general perturbation
+theory for the Landau-Lifshitz-Gilbert (LLG) equation and find its steady-state
+solution for small magnetic field amplitudes. On this basis, we derive the
+second-order expressions for the average magnetization and power loss,
+investigate their dependence on the magnetic field frequency, and analyze the
+role of subharmonic resonances resulting from the nonlinear nature of the LLG
+equation. For arbitrary amplitudes, the frequency dependence of these
+quantities is obtained from the numerical solution of this equation. The impact
+of transitions between different regimes of regular and chaotic dynamics of
+magnetization, which can be induced in nanoparticles by changing the magnetic
+field frequency, is examined in detail.",1606.07131v1
+2016-07-20,Performance of Topological Insulator Interconnects,"The poor performance of copper interconnects at the nanometer scale calls for
+new material solutions for continued scaling of integrated circuits. We propose
+the use of three dimensional time-reversal-invariant topological insulators
+(TIs), which host backscattering-protected surface states, for this purpose.
+Using semiclassical methods, we demonstrate that nanoscale TI interconnects
+have a resistance 1-3 orders of magnitude lower than copper interconnects and
+graphene nanoribbons at the nanometer scale. We use the nonequilibrium Green
+function (NEGF) formalism to measure the change in conductance of nanoscale TI
+and metal interconnects caused by the presence of impurity disorder. We show
+that metal interconnects suffer a resistance increase, relative to the clean
+limit, in excess of 500% due to disorder while the TI's surface states increase
+less than 35% in the same regime.",1607.06131v2
+2016-07-21,Rate-distance tradeoff for codes above graph capacity,"The capacity of a graph is defined as the rate of exponential growth of
+independent sets in the strong powers of the graph. In the strong power an edge
+connects two sequences if at each position their letters are equal or adjacent.
+We consider a variation of the problem where edges in the power graphs are
+removed between sequences which differ in more than a fraction $\delta$ of
+coordinates. The proposed generalization can be interpreted as the problem of
+determining the highest rate of zero undetected-error communication over a link
+with adversarial noise, where only a fraction $\delta$ of symbols can be
+perturbed and only some substitutions are allowed.
+  We derive lower bounds on achievable rates by combining graph homomorphisms
+with a graph-theoretic generalization of the Gilbert-Varshamov bound. We then
+give an upper bound, based on Delsarte's linear programming approach, which
+combines Lov\'asz' theta function with the construction used by McEliece et al.
+for bounding the minimum distance of codes in Hamming spaces.",1607.06384v1
+2016-07-25,A geometric approach to optimal nonequilibrium control: Minimizing dissipation in nanomagnetic spin systems,"Optimal control of nanomagnets has become an urgent problem for the field of
+spintronics as technological tools approach thermodynamically determined limits
+of efficiency. In complex, fluctuating systems, like nanomagnetic bits, finding
+optimal protocols is challenging, requiring detailed information about the
+dynamical fluctuations of the controlled system. We provide a new, physically
+transparent derivation of a metric tensor for which the length of a protocol is
+proportional to its dissipation. This perspective simplifies nonequilibrium
+optimization problems by recasting them in a geometric language. We then
+describe a numerical method, an instance of geometric minimum action methods,
+that enables computation of geodesics even when the number of control
+parameters is large. We apply these methods to two models of nanomagnetic bits:
+a simple Landau-Lifshitz-Gilbert description of a single magnetic spin
+controlled by two orthogonal magnetic fields and a two dimensional Ising model
+in which the field is spatially controlled. These calculations reveal
+nontrivial protocols for bit erasure and reversal, providing important,
+experimentally testable predictions for ultra-low power computing.",1607.07425v1
+2016-08-02,"Affordable echelle spectroscopy of the eccentric HAT-P-2, WASP-14 and XO-3 planetary systems with a sub-meter-class telescope","A new off-shelf low-cost echelle spectrograph was installed recently on the
+0.6m telescope at the Star\'a Lesn\'a Observatory (Slovakia). In this paper we
+describe in details the radial velocity (RV) analysis of the first three
+transiting planetary systems, HAT-P-2, WASP-14 and XO-3, observed with this
+instrument. Furthermore, we compare our data with the RV data achieved with
+echelle spectrographs of other sub-meter-, meter- and two-meter-class
+telescopes in terms of their precision. Finally, we investigate the
+applicability of our RV data for modeling orbital parameters.",1608.00745v1
+2016-08-09,Existence of weak solutions to an evolutionary model for magnetoelasticity,"We prove existence of weak solutions to an evolutionary model derived for
+magnetoelastic materials. The model is phrased in Eulerian coordinates and
+consists in particular of (i) a Navier-Stokes equation that involves magnetic
+and elastic terms in the stress tensor obtained by a variational approach, of
+(ii) a regularized transport equation for the deformation gradient and of (iii)
+the Landau-Lifshitz-Gilbert equation for the dynamics of the magnetization. The
+proof is built on a Galerkin method and a fixed-point argument. It is based on
+ideas from F.-H. Lin and the third author for systems modeling the flow of
+liquid crystals as well as on methods by G. Carbou and P. Fabrie for solutions
+of the Landau-Lifshitz equation.",1608.02992v1
+2016-08-16,Magnetic Yoking and Tunable Interactions in FePt-Based Hard/Soft Bilayers,"Assessing and controlling magnetic interactions in magnetic nanostructures
+are critical to nanomagnetic and spintronic explorations, such as magnetic
+recording media, permanent magnets, magnetic memory and logic devices, etc.
+Here we demonstrate an extremely sensitive magnetic yoking effect and tunable
+interactions in FePt based hard/soft bilayers mediated by the soft layer. Below
+the exchange length, a thin soft layer strongly exchange couples to the
+perpendicular moments of the hard layer; above the exchange length, just a few
+nanometers thicker, the soft layer moments turn in-plane and act to yoke the
+dipolar fields from the adjacent hard layer perpendicular domains. The
+evolution from exchange to dipolar-dominated interactions is experimentally
+captured by first-order reversal curves, the delta-M method, and polarized
+neutron reflectometry, and confirmed by micromagnetic simulations. These
+findings demonstrate an effective yoking approach to design and control
+magnetic interactions in wide varieties of magnetic nanostructures and devices.",1608.04630v1
+2016-08-17,Current-induced instability of domain walls in cylindrical nanowires,"We study the current-driven domain wall (DW) motion in cylindrical nanowires
+using micromagnetic simulations by implementing the Landau-Lifshitz-Gilbert
+equation with nonlocal spin-transfer torque in a finite difference
+micromagnetic package. We find that in the presence of DW Gaussian wave packets
+(spin waves) will be generated when the charge current is applied to the system
+suddenly. And this effect is excluded when using the local spin-transfer
+torque. The existence of spin waves emission indicates that transverse domain
+walls can not move arbitrarily fast in cylindrical nanowires although they are
+free from the Walker limit. We establish an upper-velocity limit for the DW
+motion by analyzing the stability of Gaussian wave packets using the local
+spin-transfer torque. Micromagnetic simulations show that the stable region
+obtained by using nonlocal spin-transfer torque is smaller than that by using
+its local counterpart. This limitation is essential for multiple domain walls
+since the instability of Gaussian wave packets will break the structure of
+multiple domain walls.",1608.04876v2
+2016-08-22,Disorder Induced Phase Transitions of Type-II Weyl Semimetal,"Weyl semimetals are a newly discovered class of materials that host
+relativistic massless Weyl fermions as their low-energy bulk excitations. Among
+this new class of materials, there exist two general types of semimetals that
+are of particular interest: type-I Weyl semimetals, that have broken inversion
+or time-reversal symmetry symmetry, and type-II Weyl semimetals, that
+additionally breaks Lorentz invariance. In this work, we use Born approximation
+to analytically demonstrate that the type-I Weyl semimetals may undergo a
+quantum phase transition to type-II Weyl semimetals in the presence of the
+finite charge and magnetic disorder when non-zero tilt exist. The phase
+transition occurs when the disorder renormalizes the topological mass, thereby
+reducing the Fermi velocity near the Weyl cone below the tilt of the cone. We
+also confirm the presence of the disorder induced phase transition in Weyl
+semimetals using exact diagonalization of a three-dimensional tight-binding
+model to calculate the resultant phase diagram of the type-I Weyl semimetal.",1608.06311v1
+2016-08-25,Convergence of a mass-lumped finite element method for the Landau-Lifshitz equation,"The dynamics of the magnetic distribution in a ferromagnetic material is
+governed by the Landau-Lifshitz equation, which is a nonlinear geometric
+dispersive equation with a nonconvex constraint that requires the magnetization
+to remain of unit length throughout the domain. In this article, we present a
+mass-lumped finite element method for the Landau-Lifshitz equation. This method
+preserves the nonconvex constraint at each node of the finite element mesh, and
+is energy nonincreasing. We show that the numerical solution of our method for
+the Landau-Lifshitz equation converges to a weak solution of the
+Landau-Lifshitz-Gilbert equation using a simple proof technique that cancels
+out the product of weakly convergent sequences. Numerical tests for both
+explicit and implicit versions of the method on a unit square with periodic
+boundary conditions are provided for structured and unstructured meshes.",1608.07312v3
+2016-09-09,An Empirical Study of Cycle Toggling Based Laplacian Solvers,"We study the performance of linear solvers for graph Laplacians based on the
+combinatorial cycle adjustment methodology proposed by
+[Kelner-Orecchia-Sidford-Zhu STOC-13]. The approach finds a dual flow solution
+to this linear system through a sequence of flow adjustments along cycles. We
+study both data structure oriented and recursive methods for handling these
+adjustments.
+  The primary difficulty faced by this approach, updating and querying long
+cycles, motivated us to study an important special case: instances where all
+cycles are formed by fundamental cycles on a length $n$ path. Our methods
+demonstrate significant speedups over previous implementations, and are
+competitive with standard numerical routines.",1609.02957v1
+2016-09-21,Harmonic space analysis of pulsar timing array redshift maps,"In this paper, we propose a new framework for treating the angular
+information in the pulsar timing array response to a gravitational wave
+background based on standard cosmic microwave background techniques. We
+calculate the angular power spectrum of the all-sky gravitational redshift
+pattern induced at the earth for both a single bright source of gravitational
+radiation and a statistically isotropic, unpolarized Gaussian random
+gravitational wave background. The angular power spectrum is the harmonic
+transform of the Hellings & Downs curve. We use the power spectrum to examine
+the expected variance in the Hellings & Downs curve in both cases. Finally, we
+discuss the extent to which pulsar timing arrays are sensitive to the angular
+power spectrum and find that the power spectrum sensitivity is dominated by the
+quadrupole anisotropy of the gravitational redshift map.",1609.06758v2
+2016-09-22,Ultrafast generation of skyrmionic defects with vortex beams: printing laser profiles on magnets,"Controlling electric and magnetic properties of matter by laser beams is
+actively explored in the broad region of condensed matter physics, including
+spintronics and magneto-optics. Here we theoretically propose an application of
+optical and electron vortex beams carrying intrinsic orbital angular momentum
+to chiral ferro- and antiferro- magnets. We analyze the time evolution of spins
+in chiral magnets under irradiation of vortex beams, by using the stochastic
+Landau-Lifshitz-Gilbert equation. We show that beam-driven nonuniform
+temperature lead to a class of ring-shaped magnetic defects, what we call
+skyrmion multiplex, as well as conventional skyrmions. We discuss the proper
+beam parameters and the optimal way of applying the beams for the creation of
+these topological defects. Our findings provide an ultrafast scheme of
+generating topological magnetic defects in a way applicable to both metallic
+and insulating chiral (anti-) ferromagnets.",1609.06816v3
+2016-10-02,Syntactic Structures and Code Parameters,"We assign binary and ternary error-correcting codes to the data of syntactic
+structures of world languages and we study the distribution of code points in
+the space of code parameters. We show that, while most codes populate the lower
+region approximating a superposition of Thomae functions, there is a
+substantial presence of codes above the Gilbert-Varshamov bound and even above
+the asymptotic bound and the Plotkin bound. We investigate the dynamics induced
+on the space of code parameters by spin glass models of language change, and
+show that, in the presence of entailment relations between syntactic parameters
+the dynamics can sometimes improve the code. For large sets of languages and
+syntactic data, one can gain information on the spin glass dynamics from the
+induced dynamics in the space of code parameters.",1610.00311v1
+2016-10-03,Linear dynamics of classical spin as Möbius transformation,"Although the overwhelming majority of natural processes occurs far from the
+equilibrium, general theoretical approaches to non-equilibrium phase
+transitions remain scarce. Recent breakthroughs introducing description of open
+dissipative systems in terms of non-Hermitian quantum mechanics allowed to
+identify a class of non-equilibrium phase transitions associated with the loss
+of combined parity (reflection) and time-reversal symmetries. Here we report
+that time evolution of a single classical spin (e.g. monodomain ferromagnet)
+governed by the Landau-Lifshitz-Gilbert-Slonczewski equation in absence of
+higher-order anisotropy terms is described by a M\""{o}bius transformation in
+complex stereographic coordinates. We identify the \textit{parity-time}
+symmetry-breaking phase transition occurring in spin-transfer torque-driven
+linear spin systems as a transition between hyperbolic and loxodromic classes
+of M\""{o}bius transformations, with the critical point of the transition
+corresponding to the parabolic transformation. This establishes the
+understanding of non-equilibrium phase transitions as topological transitions
+in configuration space.",1610.00762v1
+2016-10-11,Self-Consistent Field Theory studies of the thermodynamics and quantum spin dynamics of magnetic Skyrmions,"A self-consistent field theory is introduced and used to investigate the
+thermodynamics and spin dynamics of an $S = 1$ quantum spin system with a
+magnetic Skyrmion. The temperature dependence of the Skyrmion profile as well
+as the phase diagram are calculated. It is shown that the Skyrmion carries a
+phase transition to the ferromagnetic phase of first order with increasing
+temperature, while the magnetization of the surrounding ferromagnet undergoes a
+phase transition of second order when changing to the paramagnetic phase.
+Furthermore, the electric field driven annihilation process of the Skyrmion is
+described quantum mechanical by solving the time dependent Schr\""odinger
+equation. The results are compared with the trajectories of the semi-classical
+description of the spin expectation values using a differential equation
+similar to the classical Landau-Lifshitz-Gilbert equation.",1610.03191v2
+2016-10-12,Variational approximation of functionals defined on 1-dimensional connected sets: the planar case,"In this paper we consider variational problems involving 1-dimensional
+connected sets in the Euclidean plane, such as the classical Steiner tree
+problem and the irrigation (Gilbert-Steiner) problem. We relate them to optimal
+partition problems and provide a variational approximation through
+Modica-Mortola type energies proving a $\Gamma$-convergence result. We also
+introduce a suitable convex relaxation and develop the corresponding numerical
+implementations. The proposed methods are quite general and the results we
+obtain can be extended to $n$-dimensional Euclidean space or to more general
+manifold ambients, as shown in the companion paper [11].",1610.03839v5
+2016-10-24,"Field-free, spin-current control of magnetization in non-collinear chiral antiferromagnets","Non-collinear chiral antiferromagnets like Mn3Sn and Mn3Ge are known to show
+gigantic anomalous Hall response depending on the orientation of their inverse
+chiral magnetic order of Mn atoms in Kagome layers. Here we study the stability
+of such magnetic order in the absence of external magnetic fields on the basis
+of stochastic Landau-Lifshitz-Gilbert equation for a simplified two-dimensional
+model of these materials. We find that even without external magnetic fields,
+the ordered state is, once formed, highly stable against thermal fluctuations.
+Moreover, we show that if Mn spins are well confined inside each Kagome layers,
+by injecting spin-current using spin-filtering effect of ferromagnetic metals,
+we can control the in-plane magnetic structure in a field free way.",1610.07615v2
+2016-11-04,Struwe-like solutions for the Stochastic Harmonic Map Flow,"We give a new result on the well-posedness of the two-dimensional Stochastic
+Harmonic Map flow, whose study is motivated by the Landau-Lifshitz-Gilbert
+model for thermal fluctuations in micromagnetics. We construct strong solutions
+that belong locally to the spaces $C([s,t);H^1)\cap L^2([s,t);H^2)$, $0\leq
+s<t\leq T$. It that sense, these maps are a counterpart of the so-called
+""Struwe solutions"" of the deterministic model. We also give a natural criterion
+of uniqueness that extends A.\ Freire's Theorem to the stochastic case. Both
+results are obtained under the condition that the noise term has a trace-class
+covariance in space.",1611.01565v2
+2016-11-07,Compactness results for static and dynamic chiral skyrmions near the conformal limit,"We examine lower order perturbations of the harmonic map prob- lem from
+$\mathbb{R}^2$ to $\mathbb{S}^2$ including chiral interaction in form of a
+helicity term that prefers modulation, and a potential term that enables decay
+to a uniform background state. Energy functionals of this type arise in the
+context of magnetic systems without inversion symmetry. In the almost conformal
+regime, where these perturbations are weighted with a small parameter, we
+examine the existence of relative minimizers in a non-trivial homotopy class,
+so-called chiral skyrmions, strong compactness of almost minimizers, and their
+asymptotic limit. Finally we examine dynamic stability and compactness of
+almost minimizers in the context of the Landau-Lifshitz-Gilbert equation
+including spin-transfer torques arising from the interaction with an external
+current.",1611.01984v1
+2016-11-08,A variational method for spectral functions,"The Generalized Eigenvalue Problem (GEVP) has been used extensively in the
+past in order to reliably extract energy levels from time-dependent Euclidean
+correlators calculated in Lattice QCD. We propose a formulation of the GEVP in
+frequency space. Our approach consists of applying the model-independent
+Backus-Gilbert method to a set of Euclidean two-point functions with common
+quantum numbers. A GEVP analysis in frequency space is then applied to a matrix
+of estimators that allows us, among other things, to obtain particular linear
+combinations of the initial set of operators that optimally overlap to
+different local regions in frequency. We apply this method to lattice data from
+NRQCD. This approach can be interesting both for vacuum physics as well as for
+finite-temperature problems.",1611.02499v1
+2016-11-14,Hidden fluctuations close to a quantum bicritical point,"In this paper we describe physical properties arising in the vicinity of two
+coupled quantum phase transitions. We consider a phenomenological model based
+on two scalar order parameter fields locally coupled biquadratically and having
+a common quantum critical point as a function of a quantum tuning parameter
+such as pressure or magnetic field. A self-consistent treatment suggests that
+the uniform static susceptibilities of the two order parameter fields may have
+the same qualitative form at low temperature even where the forms differ
+sharply in the absence of the biquadratic coupling. The possible limitations of
+the self-consistent analysis leading to this prediction are considered.",1611.04621v2
+2016-11-22,New bounds of permutation codes under Hamming metric and Kendall's $τ$-metric,"Permutation codes are widely studied objects due to their numerous
+applications in various areas, such as power line communications, block
+ciphers, and the rank modulation scheme for flash memories. Several kinds of
+metrics are considered for permutation codes according to their specific
+applications. This paper concerns some improvements on the bounds of
+permutation codes under Hamming metric and Kendall's $\tau$-metric
+respectively, using mainly a graph coloring approach. Specifically, under
+Hamming metric, we improve the Gilbert-Varshamov bound asymptotically by a
+factor $n$, when the minimum Hamming distance $d$ is fixed and the code length
+$n$ goes to infinity. Under Kendall's $\tau$-metric, we narrow the gap between
+the known lower bounds and upper bounds. Besides, we also obtain some sporadic
+results under Kendall's $\tau$-metric for small parameters.",1611.07188v1
+2016-12-01,Encoding orbital angular momentum of light in magnets,"Breaking the diffraction limit and focusing laser beams to subwavelength
+scale are becoming possible with the help of recent developments in plasmonics.
+Such subwavelength focusing bridges different length scales of laser beams and
+matter. Here we consider optical vortex, or laser beam carrying orbital angular
+momentum (OAM) and discuss potential subwavelength magnetic phenomena induced
+by such laser. On the basis of numerical calculations using
+Landau-Lifshitz-Gilbert equation, we propose two OAM-dependent phenomena
+induced by optical vortices, generation of radially anisotropic spin waves and
+generation of topological defects in chiral magnets. The former could lead to
+the transient topological Hall effect through the laser-induced scalar spin
+chirality, and the latter reduces the timescale of generating skyrmionic
+defects by several orders compared to other known means.",1612.00176v2
+2016-12-26,Credibility and Dynamics of Collective Attention,"Today, social media provide the means by which billions of people experience
+news and events happening around the world. However, the absence of traditional
+journalistic gatekeeping allows information to flow unencumbered through these
+platforms, often raising questions of veracity and credibility of the reported
+information. Here we ask: How do the dynamics of collective attention directed
+toward an event reported on social media vary with its perceived credibility?
+By examining the first large-scale, systematically tracked credibility database
+of public Twitter messages (47M messages corresponding to 1,138 real-world
+events over a span of three months), we established a relationship between the
+temporal dynamics of events reported on social media and their associated level
+of credibility judgments. Representing collective attention by the aggregate
+temporal signatures of an event reportage, we found that the amount of
+continued attention focused on an event provides information about its
+associated levels of perceived credibility. Events exhibiting sustained,
+intermittent bursts of attention were found to be associated with lower levels
+of perceived credibility. In other words, as more people showed interest during
+moments of transient collective attention, the associated uncertainty
+surrounding these events also increased.",1612.08440v1
+2017-01-07,Modulation calorimetry in diamond anvil cells I: heat flow models,"Numerical simulations of heat transport in diamond anvil cells reveal a
+possibility for absolute measurements of specific heat via high-frequency
+modulation calorimetry. Such experiments could reveal and help characterize
+temperature-driven phase transitions at high-pressure, such as melting, the
+glass transition, magnetic and electric orderings, or superconducting
+transitions. Specifically, we show that calorimetric information of a sample
+cannot be directly extracted from measurements at frequencies slower than the
+timescale of conduction to the diamond anvils (10s to 100s of kHz) since the
+experiment is far from adiabatic. At higher frequencies, laser-heating
+experiments allow relative calorimetric measurements, where changes in specific
+heat of the sample are discriminated from changes in other material properties
+by scanning the heating frequency from $\sim 1$ MHz to 1 GHz. But laser-heating
+generates large temperature gradients in metal samples, preventing absolute
+heat capacities to be inferred. High-frequency Joule heating, on the other
+hand, allows accurate, absolute specific heat measurements if it can be
+performed at high-enough frequency: assuming a thin layer of KBr insulation,
+the specific heat of a 5 $\mu$m-thick metal sample heated at 100 kHz, 1 MHz, or
+10 MHz frequency would be measured with 30%, 8% or 2% accuracy, respectively.",1701.01872v1
+2017-01-08,Topological crystalline superconductors with linearly and projectively represented $C_{n}$ symmetry,"We study superconductors with $n$-fold rotational invariance both in the
+presence and in the absence of spin-orbit interactions. More specifically, we
+classify the non-interacting Hamiltonians by defining a series of $Z$-numbers
+for the Bogoliubov-de Gennes (BdG) symmetry classes of the Altland-Zimbauer
+classification of random matrices in $1$D, $2$D, and $3$D in the presence of
+discrete rotational invariance. Our analysis emphasizes the important role
+played by the angular momentum of the Cooper pairs in the system: for pairings
+of nonzero angular momentum, the rotation symmetry may be represented
+projectively, and a projective representation of rotation symmetry may have
+anomalous properties, including the anti-commutation with the time-reversal
+symmetry. In 1D and 3D, we show how an $n$-fold axis enhances the topological
+classification and give additional topological numbers; in 2D, we establish a
+relation between the Chern number (in class D and CI) and the eigenvalues of
+rotation symmetry at high-symmetry points. For each nontrivial class in 3D, we
+write down a minimal effective theory for the surface Majorana states.",1701.01944v1
+2017-01-09,Temperature dependence of shear viscosity of $SU(3)$--gluodynamics within lattice simulation,"In this paper we study the shear viscosity temperature dependence of
+$SU(3)$--gluodynamics within lattice simulation. To do so, we measure the
+correlation functions of energy-momentum tensor in the range of temperatures
+$T/T_c\in [0.9, 1.5]$. To extract the values of shear viscosity we used two
+approaches. The first one is to fit the lattice data with some physically
+motivated ansatz for the spectral function with unknown parameters and then
+determine shear viscosity. The second approach is to apply the Backus-Gilbert
+method which allows to extract shear viscosity from the lattice data
+nonparametrically. The results obtained within both approaches agree with each
+other. Our results allow us to conclude that within the temperature range
+$T/T_c \in [0.9, 1.5]$ SU(3)--gluodynamics reveals the properties of a strongly
+interacting system, which cannot be described perturbatively, and has the ratio
+$\eta/s$ close to the value ${1}/{4\pi}$ in $N = 4$ Supersymmetric Yang-Mills
+theory.",1701.02266v2
+2017-01-25,Statistical Decoding,"The security of code-based cryptography relies primarily on the hardness of
+generic decoding with linear codes. The best generic decoding algorithms are
+all improvements of an old algorithm due to Prange: they are known under the
+name of information set decoding techniques (ISD). A while ago a generic
+decoding algorithm which does not belong to this family was proposed:
+statistical decoding. It is a randomized algorithm that requires the
+computation of a large set of parity-check equations of moderate weight. We
+solve here several open problems related to this decoding algorithm.
+  We give in particular the asymptotic complexity of this algorithm, give a
+rather efficient way of computing the parity-check equations needed for it
+inspired by ISD techniques and give a lower bound on its complexity showing
+that when it comes to decoding on the Gilbert-Varshamov bound it can never be
+better than Prange's algorithm.",1701.07416v2
+2017-02-07,Giant-spin nonlinear response theory of magnetic nanoparticle hyperthermia: a field dependence study,"Understanding high-field amplitude electromagnetic heat loss phenomena is of
+great importance, in particular in the biomedical field, since the
+heat-delivery treatment plans might rely on analytical models that are only
+valid at low field amplitudes. Here, we develop a nonlinear response model
+valid for single- domain nanoparticles of larger particle sizes and higher
+field amplitudes in comparison to linear response theory. A nonlinear
+magnetization expression and a generalized heat loss power equation are
+obtained and compared with the exact solution of the stochastic
+Landau-Lifshitz-Gilbert equation assuming the giant-spin hypothesis. The model
+is valid within the hyperthermia therapeutic window and predicts a shift of
+optimum particle size and distinct heat loss field amplitude exponents.
+Experimental hyperthermia data with distinct ferrite-based nanoparticles, as
+well as third harmonic magnetization data supports the nonlinear model, which
+also has implications for magnetic particle imaging and magnetic thermometry.",1702.02022v1
+2017-02-17,Spin-orbit torque in MgO/CoFeB/Ta/CoFeB/MgO symmetric structure with interlayer antiferromagnetic coupling,"Spin current generated by spin Hall effect in the heavy metal would diffuse
+up and down to adjacent ferromagnetic layers and exert torque on their
+magnetization, called spin-orbit torque. Antiferromagnetically coupled
+trilayers, namely the so-called synthetic antiferromagnets (SAF), are usually
+employed to serve as the pinned layer of spintronic devices based on spin
+valves and magnetic tunnel junctions to reduce the stray field and/or increase
+the pinning field. Here we investigate the spin-orbit torque in
+MgO/CoFeB/Ta/CoFeB/MgO perpendicularly magnetized multilayer with interlayer
+antiferromagnetic coupling. It is found that the magnetization of two CoFeB
+layers can be switched between two antiparallel states simultaneously. This
+observation is replicated by the theoretical calculations by solving
+Stoner-Wohlfarth model and Landau-Lifshitz-Gilbert equation. Our findings
+combine spin-orbit torque and interlayer coupling, which might advance the
+magnetic memories with low stray field and low power consumption.",1702.05331v1
+2017-02-19,Multiscale simulations of topological transformations in magnetic Skyrmions,"Magnetic Skyrmions belong to the most interesting spin structures for the
+development of future information technology as they have been predicted to be
+topologically protected. To quantify their stability, we use an innovative
+multiscale approach to simulating spin dynamics based on the
+Landau-Lifshitz-Gilbert equation. The multiscale approach overcomes the
+micromagnetic limitations that have hindered realistic studies using
+conventional techniques. We first demonstrate how the stability of a Skyrmion
+is influenced by the refinement of the computational mesh and reveal that
+conventionally employed traditional micromagnetic simulations are inadequate
+for this task. Furthermore, we determine the stability quantitatively using our
+multiscale approach. As a key operation for devices, the process of
+annihilating a Skyrmion by exciting it with a spin polarized current pulse is
+analyzed, showing that Skyrmions can be reliably deleted by designing the pulse
+shape.",1702.05767v1
+2017-02-21,Spin texture motion in antiferromagnetic and ferromagnetic nanowires,"We propose a Hamiltonian dynamics formalism for the current and magnetic
+field driven dynamics of ferromagnetic and antiferromagnetic domain walls in
+one dimensional systems. To demonstrate the power of this formalism, we derive
+Hamilton equations of motion via Poisson brackets based on the
+Landau-Lifshitz-Gilbert phenomenology, and add dissipative dynamics via the
+evolution of the energy. We use this approach to study current induced domain
+wall motion and compute the drift velocity. For the antiferromagnetic case, we
+show that a nonzero magnetic moment is induced in the domain wall, which
+indicates that an additional application of a magnetic field would influence
+the antiferromagnetic domain-wall dynamics. We consider both cases of the
+magnetic field being parallel and transverse to the N{\'e}el field. Based on
+this formalism, we predict an orientation switch mechanism for
+antiferromagnetic domain walls which can be tested with the recently discovered
+N{\'e}el spin orbit torques.",1702.06274v1
+2017-02-23,Fulde-Ferrell States in Inverse Proximity Coupled Magnetically-Doped Topological Heterostructures,"We study the superconducting properties of the thin film BCS superconductor
+proximity coupled to a magnetically doped topological insulator(TI). Using the
+mean field theory, we show that Fulde-Ferrell(FF) pairing can be induced in the
+conventional superconductor by having inverse proximity effect(IPE). This
+occurs when the IPE of the TI to the superconductor is large enough that the
+normal band of the superconductor possesses a proximity induced spin-orbit
+coupling and magnetization. We find that the energetics of the different
+pairings are dependent on the coupling strength between the TI and the BCS
+superconductor and the thickness of the superconductor film. As the thickness
+of the superconductor film is increased, we find a crossover from the FF
+pairing to the BCS pairing phase. This is a consequence of the increased number
+of the superconducting bands, which favor the BCS pairing, implying that the FF
+phase can only be observed in the thin-film limit. In addition, we also propose
+transport experiments that show distinct signatures of the FF phase.",1702.07383v1
+2017-02-27,Quantum critical scaling and fluctuations in Kondo lattice materials,"We propose a new phenomenological framework for three classes of Kondo
+lattice materials that incorporates the interplay between the fluctuations
+associated with the antiferromagnetic quantum critical point and those produced
+by the hybridization quantum critical point that marks the end of local moment
+behavior. We show that these fluctuations give rise to two distinct regions of
+quantum critical scaling: hybridization fluctuations are responsible for the
+logarithmic scaling in the density of states of the heavy electron Kondo liquid
+that emerges below the coherence temperature T*; while the unconventional power
+law scaling in the resistivity that emerges at lower temperatures below T_QC
+may reflect the combined effects of hybridization and antiferromagnetic quantum
+critical fluctuations. Our framework is supported by experimental measurements
+on CeCoIn5, CeRhIn5 and other heavy electron materials.",1702.08132v2
+2017-03-09,On linear complementary-dual multinegacirculant codes,"Linear codes with complementary-duals (LCD) are linear codes that intersect
+with their dual trivially. Multinegacirculant codes of index $2$ that are LCD
+are characterized algebraically and some good codes are found in this family.
+Exact enumeration is performed for indices 2 and 3, and for all indices $t$ for
+a special case of the co-index by using their concatenated structure.
+Asymptotic existence results are derived for the special class of such codes
+that are one-generator and have co-index a power of two by means of Dickson
+polynomials. This shows that there are infinite families of LCD
+multinegacirculant codes with relative distance satisfying a modified
+Varshamov-Gilbert bound.",1703.03115v1
+2017-03-16,Electronic transport in a two-dimensional superlattice engineered via self-assembled nanostructures,"Nanoscience offers a unique opportunity to design modern materials from the
+bottom up, via low-cost, solution processed assembly of nanoscale building
+blocks. These systems promise electronic band structure engineering using not
+only the nanoscale structural modulation, but also the mesoscale spatial
+patterning, although experimental realization of the latter has been
+challenging. Here we design and fabricate a new type of artificial solid by
+stacking graphene on a self-assembled, nearly periodic array of nanospheres,
+and experimentally observe superlattice miniband effects. We find conductance
+dips at commensurate fillings of charge carriers per superlattice unit cell,
+which are key features of minibands that are induced by the quasi-periodic
+deformation of the graphene lattice. These dips become stronger when the
+lattice strain is larger. Using a tight-binding model, we simulate the effect
+of lattice deformation as a parameter affecting the inter-atomic hopping
+integral, and confirm the superlattice transport behavior. This 2D
+material-nanoparticle heterostructure enables facile band structure engineering
+via self-assembly, promising for large area electronics and optoelectronics
+applications.",1703.05689v3
+2017-03-27,Dipolar ferromagnetism in three-dimensional superlattices of nanoparticles,"A series of atomistic finite temperature simulations on a model of an FCC
+lattice of maghemite nanoparticles using the stochastic Landau-Lifshitz-Gilbert
+(sLLG) equation are presented. The model exhibits a ferromagnetic transition
+that is in good agreement with theoretical expectations. The simulations also
+reveal an orientational disorder in the orientational order parameter for $T <
+0.5 T_c$ due to pinning of the surface domain walls of the nanoparticles by
+surface vacancies. The extent of the competition between surface pinning and
+dipolar interactions provides support for the conjecture that recent
+measurements on systems of FCC superlattices of iron-oxide nanoparticles
+provide evidence for dipolar ferromagnetism is discussed.",1703.09290v1
+2017-03-06,Ultralow Energy Analog Straintronics Using Multiferroic Composites,"Electric field-induced magnetization switching in multiferroics holds
+profound promise for ultra-low-energy computing in beyond Moore's law era.
+Bistable nanomagnets in the multiferroics are usually deemed to be suitable for
+storing a binary bit of information and switching between the two stable states
+allows us to process digital information. However, it requires to process
+continuous analog signals too for seamless integration of nanomagnetic devices
+in our future information processing systems. Here, we show that it is possible
+to harness the analog nature in the magnetostrictive nanomagnets, contrary to
+writing a digital bit of information. By solving stochastic
+Landau-Lifshitz-Gilbert equation of magnetization dynamics at room-temperature,
+we demonstrate such possibility and show that there exists a transistor-like
+high-gain region in the input-output characteristics of the magnetostrictive
+nanomagnets in strain-mediated multiferroic composites. This can be the basis
+of ultra-low-energy analog and mixed signal precessing in our future
+information processing systems and it eliminates the requirement of using
+charge-based transistors.",1704.02337v1
+2017-04-12,The Origin of Sequential Chromospheric Brightenings,"Sequential chromospheric brightenings (SCBs) are often observed in the
+immediate vicinity of erupting flares and are associated with coronal mass
+ejections. Since their initial discovery in 2005, there have been several
+subsequent investigations of SCBs. These studies have used differing detection
+and analysis techniques, making it difficult to compare results between
+studies. This work employs the automated detection algorithm of Kirk et al.
+(Solar Phys. 283, 97, 2013) to extract the physical characteristics of SCBs in
+11 flares of varying size and intensity. We demonstrate that the magnetic
+substructure within the SCB appears to have a significantly smaller area than
+the corresponding H-alpha emission. We conclude that SCBs originate in the
+lower corona around 0.1 R_sun above the photosphere, propagate away from the
+flare center at speeds of 35 - 85 km/s, and have peak photosphere magnetic
+intensities of 148 +/- 2.9 G. In light of these measurements, we infer SCBs to
+be distinctive chromospheric signatures of erupting coronal mass ejections.",1704.03828v1
+2017-04-12,Relationships Between Sequential Chromospheric Brightening and the Corona,"The chromosphere is a complex region that acts as an intermediary between the
+magnetic flux emergence in the photosphere and the magnetic features seen in
+the corona. Large eruptions in the chromosphere of flares and filaments are
+often accompanied by ejections of coronal mass off the sun. Several studies
+have observed fast-moving progressive trains of compact bright points (called
+Sequential Chromospheric Brightenings or SCBs) streaming away from
+chromospheric flares that also produce a coronal mass ejection (CME). In this
+work, we review studies of SCBs and search for commonalties between them. We
+place these findings into a larger context with contemporary chromospheric and
+coronal observations. SCBs are fleeting indicators of the solar atmospheric
+environment as it existed before their associated eruption. Since they appear
+at the very outset of a flare eruption, SCBs are good early indication of a CME
+measured in the chromosphere.",1704.03835v1
+2017-05-16,Constructive mathematics,"This text is reproduced with the kind permission of Fran\c{c}ois Ap\'ery.
+  It was originally edited by Fran\c{c}ois Gu\'enard and Gilbert Leli\`evre for
+the book ""Penser les math\'ematiques"".
+  It is the modified and abridged version of a text that appeared previously as
+S\'eminaire de philosophie et math\'ematiques de l'\'Ecole normale sup\'erieure
+(s\'eance du 26 avril 1976), Paris, IREM Paris-Nord, 1980, 15 pp.,
+http://www.numdam.org/item?id=SPHM_1976___1_A1_0, as well as in Langage et
+pens\'ee math\'ematiques: actes du colloque international (Luxembourg, 9-11
+juin 1976), Luxembourg, Centre universitaire de Luxembourg, 1976, pp. 391--410.
+  In its introduction, Ap\'ery writes: ""In default of convincing, this text can
+set the record straight: we show that the constructive conception does not
+mutilate, on the contrary, it enriches classical mathematics.""",1705.05581v2
+2017-05-17,Magnetic-Visual Sensor Fusion based Medical SLAM for Endoscopic Capsule Robot,"A reliable, real-time simultaneous localization and mapping (SLAM) method is
+crucial for the navigation of actively controlled capsule endoscopy robots.
+These robots are an emerging, minimally invasive diagnostic and therapeutic
+technology for use in the gastrointestinal (GI) tract. In this study, we
+propose a dense, non-rigidly deformable, and real-time map fusion approach for
+actively controlled endoscopic capsule robot applications. The method combines
+magnetic and vision based localization, and makes use of frame-to-model fusion
+and model-to-model loop closure. The performance of the method is demonstrated
+using an ex-vivo porcine stomach model. Across four trajectories of varying
+speed and complexity, and across three cameras, the root mean square
+localization errors range from 0.42 to 1.92 cm, and the root mean square
+surface reconstruction errors range from 1.23 to 2.39 cm.",1705.06196v2
+2017-05-21,First-Order Reversal Curves of the Magnetostructural Phase Transition in FeTe,"We apply the first-order reversal curve (FORC) method, borrowed from studies
+of ferromagnetic materials, to the magneto-structural phase transition of FeTe.
+FORC measurements reveal two features in the hysteretic phase transition, even
+in samples where traditional temperature measurements display only a single
+transition. For Fe1.13Te, the influence of magnetic field suggests that the
+main feature is primarily structural while a smaller, slightly
+higher-temperature transition is magnetic in origin. By contrast Fe1.03Te has a
+single transition which shows a uniform response to magnetic field, indicating
+a stronger coupling of the magnetic and structural phase transitions. We also
+introduce uniaxial stress, which spreads the distribution width without
+changing the underlying energy barrier of the transformation. The work shows
+how FORC can help disentangle the roles of the magnetic and structural phase
+transitions in FeTe.",1705.07380v1
+2017-05-24,Towards Understanding the Invertibility of Convolutional Neural Networks,"Several recent works have empirically observed that Convolutional Neural Nets
+(CNNs) are (approximately) invertible. To understand this approximate
+invertibility phenomenon and how to leverage it more effectively, we focus on a
+theoretical explanation and develop a mathematical model of sparse signal
+recovery that is consistent with CNNs with random weights. We give an exact
+connection to a particular model of model-based compressive sensing (and its
+recovery algorithms) and random-weight CNNs. We show empirically that several
+learned networks are consistent with our mathematical analysis and then
+demonstrate that with such a simple theoretical framework, we can obtain
+reasonable re- construction results on real images. We also discuss gaps
+between our model assumptions and the CNN trained for classification in
+practical scenarios.",1705.08664v1
+2017-03-06,Ultra-low-energy Electric field-induced Magnetization Switching in Multiferroic Heterostructures,"Electric field-induced magnetization switching in multiferroics is intriguing
+for both fundamental studies and potential technological applications. Here, we
+review the recent developments on electric field-induced magnetization
+switching in multiferroic heterostructures. Particularly, we study the dynamics
+of magnetization switching between the two stable states in a shape-anisotropic
+single-domain nanomagnet using stochastic Landau-Lifshitz-Gilbert (LLG)
+equation in the presence of thermal fluctuations. For magnetostrictive
+nanomagnets in strain-coupled multiferroic composites, such study of
+magnetization dynamics, contrary to steady-state scenario, revealed intriguing
+new phenomena on binary switching mechanism. While the traditional method of
+binary switching requires to tilt the potential profile to the desired state of
+switching, we show that no such tilting is necessary to switch successfully
+since the magnetization's excursion out of magnet's plane can generate a
+built-in asymmetry during switching. We also study the switching dynamics in
+multiferroic heterostructures having magnetoelectric coupling at the interface
+and magnetic exchange coupling that can facilitate to maintain the direction of
+switching with the polarity of the applied electric field. We calculate the
+performance metrics like switching delay and energy dissipation during
+switching while simulating LLG dynamics. The performance metrics turn out to be
+very encouraging for potential technological applications.",1706.03039v1
+2017-06-11,Local List Recovery of High-rate Tensor Codes and Applications,"In this work, we give the first construction of high-rate locally
+list-recoverable codes. List-recovery has been an extremely useful building
+block in coding theory, and our motivation is to use these codes as such a
+building block. In particular, our construction gives the first
+capacity-achieving locally list-decodable codes (over constant-sized alphabet);
+the first capacity achieving globally list-decodable codes with nearly linear
+time list decoding algorithm (once more, over constant-sized alphabet); and a
+randomized construction of binary codes on the Gilbert-Varshamov bound that can
+be uniquely decoded in near-linear-time, with higher rate than was previously
+known.
+  Our techniques are actually quite simple, and are inspired by an approach of
+Gopalan, Guruswami, and Raghavendra (Siam Journal on Computing, 2011) for
+list-decoding tensor codes. We show that tensor powers of (globally)
+list-recoverable codes are ""approximately"" locally list-recoverable, and that
+the ""approximately"" modifier may be removed by pre-encoding the message with a
+suitable locally decodable code. Instantiating this with known constructions of
+high-rate globally list-recoverable codes and high-rate locally decodable codes
+finishes the construction.",1706.03383v1
+2017-05-31,Local Differential Privacy for Physical Sensor Data and Sparse Recovery,"In this work we explore the utility of locally differentially private thermal
+sensor data. We design a locally differentially private recovery algorithm for
+the 1-dimensional, discrete heat source location problem and analyse its
+performance in terms of the Earth Mover Distance error. Our work indicates that
+it is possible to produce locally private sensor measurements that both keep
+the exact locations of the heat sources private and permit recovery of the
+""general geographic vicinity"" of the sources. We also discuss the relationship
+between the property of an inverse problem being ill-conditioned and the amount
+of noise needed to maintain privacy.",1706.05916v4
+2017-06-22,High-performance nanoscale topological energy transduction,"The realization of high-performance, small-footprint, on-chip inductors
+remains a challenge in radio-frequency and power microelectronics, where they
+perform vital energy transduction in filters and power converters. Modern
+planar inductors consist of metallic spirals that consume significant chip
+area, resulting in low inductance densities. We present a novel method for
+magnetic energy transduction that utilizes ferromagnetic islands (FIs) on the
+surface of a 3D time-reversal-invariant topological insulator (TI) to produce
+paradigmatically different inductors. Depending on the chemical potential, the
+FIs induce either an anomalous or quantum anomalous Hall effect in the
+topological surface states. These Hall effects direct current around the FIs,
+concentrating magnetic flux and producing a highly inductive device. Using a
+novel self-consistent simulation that couples AC non-equilibrium Green
+functions to fully electrodynamic solutions of Maxwell's equations, we
+demonstrate excellent inductance densities up to terahertz frequencies, thus
+harnessing the unique properties of topological materials for practical device
+applications.",1706.07381v1
+2017-06-28,Extension and Applications of a Variational Approach with Deformed Derivatives,"We have recently presented an extension of the standard variational calculus
+to include the presence of deformed derivatives in the Lagrangian of a system
+of particles and in the Lagrangian density of field-theoretic models. Classical
+Euler-Lagrange equations and the Hamiltonian formalism have been re-assessed in
+this approach. Whenever applied to a number of physical systems, the resulting
+dynamical equations come out to be the correct ones found in the literature,
+specially with mass-dependent and with non-linear equations for classical and
+quantum-mechanical systems. In the present contribution, we extend the
+variational approach with the intervalar form of deformed derivatives to study
+higher-order dissipative systems, with application to concrete situations, such
+as an accelerated point charge - this is the problem of the
+Abraham-Lorentz-Dirac force - to stochastic dynamics like the Langevin, the
+advection-convection-reaction and Fokker-Planck equations, Korteweg-de Vries
+equation, Landau-Lifshits-Gilbert equation and the Caldirola-Kanai Hamiltonian.
+By considering these different applications, we show that the formulation
+investigated in this paper may be a simple and promising path for dealing with
+dissipative, non-linear and stochastic systems through the variational
+approach.",1706.09504v1
+2017-07-06,Relaxation time and critical slowing down of a spin-torque oscillator,"The relaxation phenomena of spin-torque oscillators consisting of
+nanostructured ferromagnets are interesting research targets in magnetism. A
+theoretical study on the relaxation time of a spin-torque oscillator from one
+self-oscillation state to another is investigated. By solving the
+Landau-Lifshitz-Gilbert equation both analytically and numerically, it is shown
+that the oscillator relaxes to the self-oscillation state exponentially within
+a few nanoseconds, except when magnetization is close to a critical point. The
+relaxation rate, which is an inverse of relaxation time, is proportional to the
+current. On the other hand, a critical slowing down appears near the critical
+point, where relaxation is inversely proportional to time, and the relaxation
+time becomes on the order of hundreds of nanoseconds. These conclusions are
+primarily obtained for a spin-torque oscillator consisting of a perpendicularly
+magnetized free layer and an in-plane magnetized pinned layer, and are further
+developed for application to arbitrary types of spin-torque oscillators.",1707.01960v1
+2017-07-07,Pandeia: A Multi-mission Exposure Time Calculator for JWST and WFIRST,"Pandeia is the exposure time calculator (ETC) system developed for the James
+Webb Space Telescope (JWST) that will be used for creating JWST proposals. It
+includes a simulation-hybrid Python engine that calculates the two-dimensional
+pixel-by-pixel signal and noise properties of the JWST instruments. This allows
+for appropriate handling of realistic point spread functions, MULTIACCUM
+detector readouts, correlated detector readnoise, and multiple photometric and
+spectral extraction strategies. Pandeia includes support for all the JWST
+observing modes, including imaging, slitted/slitless spectroscopy, integral
+field spectroscopy, and coronagraphy. Its highly modular, data-driven design
+makes it easily adaptable to other observatories. An implementation for use
+with WFIRST is also available.",1707.02202v2
+2017-07-10,Convex optimization over classes of multiparticle entanglement,"A well-known strategy to characterize multiparticle entanglement utilizes the
+notion of stochastic local operations and classical communication (SLOCC), but
+characterizing the resulting entanglement classes is difficult. Given a
+multiparticle quantum state, we first show that Gilbert's algorithm can be
+adapted to prove separability or membership in a certain entanglement class. We
+then present two algorithms for convex optimization over SLOCC classes. The
+first algorithm uses a simple gradient approach, while the other one employs
+the accelerated projected-gradient method. For demonstration, the algorithms
+are applied to the likelihood-ratio test using experimental data on bound
+entanglement of a noisy four-photon Smolin state [Phys. Rev. Lett. 105, 130501
+(2010)].",1707.02958v3
+2017-07-13,Collective charge excitations and the metal-insulator transition in the square lattice Hubbard-Coulomb model,"In this article, we discuss the non-trivial collective charge excitations
+(plasmons) of the extended square-lattice Hubbard model. Using a fully
+non-perturbative approach, we employ the hybrid Monte Carlo algorithm to
+simulate the system at half-filling. A modified Backus-Gilbert method is
+introduced to obtain the spectral functions via numerical analytic
+continuation. We directly compute the single-particle density of states which
+demonstrates the formation of Hubbard bands in the strongly-correlated phase.
+The momentum-resolved charge susceptibility is also computed on the basis of
+the Euclidean charge density-density correlator. In agreement with previous
+EDMFT studies, we find that at large strength of the electron-electron
+interaction, the plasmon dispersion develops two branches.",1707.04212v2
+2017-07-25,Partially Ionized Plasmas in Astrophysics,"Partially ionized plasmas are found across the Universe in many different
+astrophysical environments. They constitute an essential ingredient of the
+solar atmosphere, molecular clouds, planetary ionospheres and protoplanetary
+disks, among other environments, and display a richness of physical effects
+which are not present in fully ionized plasmas. This review provides an
+overview of the physics of partially ionized plasmas, including recent advances
+in different astrophysical areas in which partial ionization plays a
+fundamental role. We outline outstanding observational and theoretical
+questions and discuss possible directions for future progress.",1707.07975v2
+2017-07-14,Spatially variant PSF modeling in confocal macroscopy,"Point spread function (PSF) plays an essential role in image reconstruction.
+In the context of confocal microscopy, optical performance degrades towards the
+edge of the field of view as astigmatism, coma and vignetting. Thus, one should
+expect the related artifacts to be even stronger in macroscopy, where the field
+of view is much larger. The field aberrations in macroscopy fluorescence
+imaging system was observed to be symmetrical and to increase with the distance
+from the center of the field of view. In this paper we propose an experiment
+and an optimization method for assessing the center of the field of view. The
+obtained results constitute a step towards reducing the number of parameters in
+macroscopy PSF model.",1707.09858v1
+2017-08-09,Bubble Magnetometry of Nanoparticle Heterogeneity and Interaction,"Bubbles have a rich history as transducers in particle-physics experiments.
+In a solid-state analogue, we use bubble domains in nanomagnetic films to
+measure magnetic nanoparticles. This technique can determine the magnetic
+orientation of a single nanoparticle in a fraction of a second, and generate a
+full hysteresis loop in a few seconds, which is much faster than any other
+reported technique. We achieve this unprecedented speed by tuning the
+nanomagnetic properties of the films, including the Dzyaloshinskii-Moriya
+interaction, in the first application of topological protection from the
+skyrmion state to a nanoparticle sensor. We demonstrate the technique on
+iron/nickel nanorods and iron oxide nanoparticles, which delineate a wide range
+of properties and applications. Bubble magnetometry enables the first
+measurement with high throughput for statistical analysis of the magnetic
+hysteresis of dispersed nanoparticles, and the first direct measurement of a
+transition from superparamagnetic behavior as single nanoparticles to
+collective behavior in nanoscale agglomerates. These results demonstrate a
+breakthrough capability for measuring the heterogeneity and interaction of
+magnetic nanoparticles.",1708.02706v2
+2017-08-18,Antiferromagnetic nano-oscillator in external magnetic fields,"We describe the dynamics of an antiferromagnetic nano-oscillator in an
+external magnetic field of any given time distribution. The oscillator is
+powered by a spin current originating from spin-orbit effects in a neighboring
+heavy metal layer, and is capable of emitting a THz signal in the presence of
+an additional easy-plane anisotropy. We derive an analytical formula describing
+the interaction between such a system and an external field, which can affect
+the output signal character. Interactions with magnetic pulses of different
+shapes, with a sinusoidal magnetic field and with a sequence of rapidly
+changing magnetic fields are discussed. We also perform numerical simulations
+based on the Landau-Lifshitz-Gilbert equation with spin-transfer torque effects
+to verify the obtained results and find a very good quantitative agreement
+between analytical and numerical predictions.",1708.05590v2
+2017-09-07,A sharp bound for winning within a proportion of the maximum of a sequence,"This note considers a variation of the full-information secretary problem
+where the random variables to be observed are independent and identically
+distributed. Consider $X_1,\dots,X_n$ to be an independent sequence of random
+variables, let $M_n:=\max\{X_1,\dots,X_n\}$, and the objective is to select the
+maximum of the sequence. What is the maximum probability of ""stopping at the
+maximum""? That is, what is the stopping time $\tau$ adapted to $X_1,...,X_n$
+that maximizes $P(X_{\tau}=M_n)$? This problem was examined by Gilbert and
+Mosteller \cite{GilMost} when in addition the common distribution is
+continuous. The optimal win probability in this case is denoted by
+$v_{n,max}^*$. What if it is desired to ""stop within a proportion of the
+maximum""? That is, for $0<\alpha<1$, what is the stopping rule $\tau$ that
+maximizes $P(X_{\tau} \geq \alpha M_n)$? In this note both problems are treated
+as games, it is proven that for any continuous random variable $X$, if $\tau^*$
+is the optimal stopping rule then $P(X_{\tau^*} \geq \alpha M_n)\geq
+v_{n,max}^*$, and this lower bound is sharp. Some examples and another
+interesting result are presented.",1709.02416v1
+2017-09-18,"Endo-VMFuseNet: Deep Visual-Magnetic Sensor Fusion Approach for Uncalibrated, Unsynchronized and Asymmetric Endoscopic Capsule Robot Localization Data","In the last decade, researchers and medical device companies have made major
+advances towards transforming passive capsule endoscopes into active medical
+robots. One of the major challenges is to endow capsule robots with accurate
+perception of the environment inside the human body, which will provide
+necessary information and enable improved medical procedures. We extend the
+success of deep learning approaches from various research fields to the problem
+of uncalibrated, asynchronous, and asymmetric sensor fusion for endoscopic
+capsule robots. The results performed on real pig stomach datasets show that
+our method achieves sub-millimeter precision for both translational and
+rotational movements and contains various advantages over traditional sensor
+fusion techniques.",1709.06041v2
+2017-09-22,On self-dual negacirculant codes of index two and four,"In this paper, we study a special kind of factorization of $x^n+1$ over
+$\mathbb{F}_q, $ with $q$ a prime power $\equiv 3~({\rm mod}~4)$ when $n=2p,$
+with $p\equiv 3~({\rm mod}~4)$ and $p$ is a prime. Given such a $q$ infinitely
+many such $p$'s exist that admit $q$ as a primitive root by the Artin
+conjecture in arithmetic progressions. This number theory conjecture is known
+to hold under GRH. We study the double (resp. four)-negacirculant codes over
+finite fields $\mathbb{F}_q, $ of co-index such $n$'s, including the exact
+enumeration of the self-dual subclass, and a modified Varshamov-Gilbert bound
+on the relative distance of the codes it contains.",1709.07546v2
+2017-03-06,Ultra-Low-Energy Straintronics Using Multiferroic Composites,"The primary impediment to continued improvement of charge-based electronics
+is the excessive energy dissipation incurred in switching a bit of information.
+With suitable choice of materials, devices made of multiferroic composites,
+i.e., strain-coupled piezoelectric-magnetostrictive heterostructures, dissipate
+miniscule amount of energy of ~1 attojoule at room-temperature, while switching
+in sub-nanosecond delay. Apart from devising memory bits, such devices can be
+also utilized for building logic, so that they can be deemed suitable for
+computing purposes as well. Here, we first review the current state of the art
+for building nanoelectronics using multiferroic composites. On a recent
+development, it is shown that these multiferroic straintronic devices can be
+also utilized for analog signal processing, with suitable choice of materials.
+By solving stochastic Landau-Lifshitz-Gilbert equation of magnetization
+dynamics at room-temperature, it is shown that we can achieve a voltage gain,
+i.e., these straintronic devices can act as voltage amplifiers.",1710.00612v1
+2017-10-12,Modeling the aging kinetics of zirconia ceramics,"Yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) with different
+microstructures were elaborated. The isothermal tetragonal to monoclinic
+transformation was investigated at 134 {\deg}C in steam by X-ray diffraction,
+Atomic Force Microscopy (AFM) and optical interferometry. The aging kinetics
+were analyzed in terms of nucleation and growth, using the Mehl-Avrami-Johnson
+(MAJ) formalism. Numerical simulation of the aging of zirconia surfaces was
+also conducted, and the results were used to better fit the aging kinetics. The
+simulation shows that the exponent of the MAJ laws is controlled not only by
+the nucleation and growth mechanisms, but also - and mainly - by their
+respective kinetic parameters. Measurements of nucleation and growth rates at
+the surface, at the beginning of aging, and the use of numerical simulation
+allow the accurate prediction of aging kinetics.",1710.04454v1
+2017-10-13,Microstructural investigation of the aging behavior of $(3Y-TZP)-Al_2O_3$ composites,"The low temperature autoclave aging behavior of zirconia toughened alumina
+composites processed by a classical powder mixing processing route was analyzed
+using atomic force microscopy (AFM), scanning electron microscopy and X-Ray
+diffraction. The transformation was evaluated in terms of nucleation and
+growth, assessed by XRD. The time-temperature equivalency of the transformation
+was used to measure an apparent activation energy of the nucleation stage of
+the transformation of 78kJ/mol. The microstructural features influencing the
+transformation were identified, and the influence of the alumina matrix on the
+transformation was investigated. Transformation progression grain by grain was
+observed by AFM. Transformation does not only occur in zirconia agglomerates
+but also in isolated zirconia grains. The matrix could partially inhibit the
+transformation. This behavior could be rationalized considering the
+constraining effect of the alumina matrix, shape strain accommodation arguments
+and microstructural homogeneity effects.",1710.04923v1
+2017-10-16,Tunable Low Density Palladium Nanowire Foams,"Nanostructured palladium foams offer exciting potential for applications in
+diverse fields such as catalyst, fuel cell, and particularly hydrogen storage
+technologies. We have fabricated palladium nanowire foams using a cross-linking
+and freeze-drying technique. These foams have a tunable density down to 0.1% of
+the bulk, and a surface area to volume ratio of up to 1,540,000:1. They exhibit
+highly attractive characteristics for hydrogen storage, in terms of loading
+capacity, rate of absorption and heat of absorption. The hydrogen
+absorption/desorption process is hysteretic in nature, accompanied by
+substantial lattice expansion/contraction as the foam converts between Pd and
+PdHx.",1710.05906v1
+2017-10-19,An estimate for the thermal photon rate from lattice QCD,"We estimate the production rate of photons by the quark-gluon plasma in
+lattice QCD. We propose a new correlation function which provides better
+control over the systematic uncertainty in estimating the photon production
+rate at photon momenta in the range {\pi}T/2 to 2{\pi}T. The relevant Euclidean
+vector current correlation functions are computed with $N_{\mathrm f}$ = 2
+Wilson clover fermions in the chirally-symmetric phase. In order to estimate
+the photon rate, an ill-posed problem for the vector-channel spectral function
+must be regularized. We use both a direct model for the spectral function and a
+model-independent estimate from the Backus-Gilbert method to give an estimate
+for the photon rate.",1710.07050v1
+2017-10-26,Spin dynamics in MgO based magnetic tunnel junctions with dynamical exchange coupling,"We study the spin dynamics in Fe|MgO|Fe tunnel junction with the dynamical
+exchange coupling by coupled Landau-Lifshitz-Gilbert equations. The effects of
+spin pumping on the spin dynamics are investigated in detail. It is observed
+that the spin pumping can stabilize a quasi-antiparallel state rather than a
+quasi-parallel one. More interestingly, our work suggests that the spin pumping
+torque can efficiently modulate the magnetization, similar to the
+thermal-bias-driven and electricbias-driven spin torques.",1710.09666v2
+2017-10-27,Bulk and edge spin transport in topological magnon insulators,"We investigate the spin transport properties of a topological magnon
+insulator, a magnetic insulator characterized by topologically nontrivial bulk
+magnon bands and protected magnon edge modes located in the bulk band gaps.
+Employing the Landau-Lifshitz-Gilbert phenomenology, we calculate the spin
+current driven through a normal metal$|$topological magnon insulator$|$normal
+metal heterostructure by a spin accumulation imbalance between the metals, with
+and without random lattice defects. We show that bulk and edge transport are
+characterized by different length scales. This results in a characteristic
+system size where the magnon transport crosses over from being bulk-dominated
+for small systems to edge-dominated for larger systems. These findings are
+generic and relevant for topological transport in systems of nonconserved
+bosons.",1710.09998v2
+2017-10-30,Spin-transfer Antiferromagnetic Resonance,"Currents can induce spin excitations in antiferromagnets, even when they are
+insulating. We investigate how spin transfer can cause antiferromagnetic
+resonance in bilayers and trilayers that consist of one antiferromagnetic
+insulator and one or two metals. An ac voltage applied to the metal generates a
+spin Hall current that drives the magnetic moments in the antiferromagnet. We
+consider excitation of the macrospin mode and of transverse standing-spin-wave
+modes. By solving the Landau-Lifshitz-Gilbert equation in the antiferromagnetic
+insulator and the spin-diffusion equation in the normal metal, we derive
+analytical expressions for the spin-Hall-magnetoresistance and spin-pumping
+inverse-spin-Hall dc voltages. In bilayers, the two contributions compensate
+each other and cannot easily be distinguished. We present numerical results for
+a MnF$_2|$Pt bilayer. Trilayers facilitate separation of the
+spin-Hall-magnetoresistance and spin-pumping voltages, thereby revealing more
+information about the spin excitations. We also compute the decay of the pumped
+spin current through the antiferromagnetic layer as a function of frequency and
+the thickness of the antiferromagnetic layer.",1710.10909v1
+2017-10-31,Compact Multi-Class Boosted Trees,"Gradient boosted decision trees are a popular machine learning technique, in
+part because of their ability to give good accuracy with small models. We
+describe two extensions to the standard tree boosting algorithm designed to
+increase this advantage. The first improvement extends the boosting formalism
+from scalar-valued trees to vector-valued trees. This allows individual trees
+to be used as multiclass classifiers, rather than requiring one tree per class,
+and drastically reduces the model size required for multiclass problems. We
+also show that some other popular vector-valued gradient boosted trees
+modifications fit into this formulation and can be easily obtained in our
+implementation. The second extension, layer-by-layer boosting, takes smaller
+steps in function space, which is empirically shown to lead to a faster
+convergence and to a more compact ensemble. We have added both improvements to
+the open-source TensorFlow Boosted trees (TFBT) package, and we demonstrate
+their efficacy on a variety of multiclass datasets. We expect these extensions
+will be of particular interest to boosted tree applications that require small
+models, such as embedded devices, applications requiring fast inference, or
+applications desiring more interpretable models.",1710.11547v1
+2017-11-14,Stationary Vacuum Black Holes in 5 Dimensions,"We study the problem of asymptotically flat bi-axially symmetric stationary
+solutions of the vacuum Einstein equations in $5$-dimensional spacetime. In
+this setting, the cross section of any connected component of the event horizon
+is a prime $3$-manifold of positive Yamabe type, namely the $3$-sphere $S^3$,
+the ring $S^1\times S^2$, or the lens space $L(p,q)$. The Einstein vacuum
+equations reduce to an axially symmetric harmonic map with prescribed
+singularities from $\mathbb{R}^3$ into the symmetric space
+$SL(3,\mathbb{R})/SO(3)$. In this paper, we solve the problem for all possible
+topologies, and in particular the first candidates for smooth vacuum
+non-degenerate black lenses are produced. In addition, a generalization of this
+result is given in which the spacetime is allowed to have orbifold
+singularities. We also formulate conditions for the absence of conical
+singularities which guarantee a physically relevant solution.",1711.05229v2
+2017-11-27,Voltage induced switching of an antiferromagnetically ordered topological Dirac semimetal,"An antiferromagnetic semimetal has been recently identified as a new member
+of topological semimetals that may host three-dimensional symmetry-protected
+Dirac fermions. A reorientation of the N\'{e}el vector may break the underlying
+symmetry and open a gap in the quasi-particle spectrum, inducing the
+(semi)metal-insulator transition. Here, we predict that such transition may be
+controlled by manipulating the chemical potential location of the material. We
+perform both analytical and numerical analysis on the thermodynamic potential
+of the model Hamiltonian and find that the gapped spectrum is preferred when
+the chemical potential is located at the Dirac point. As the chemical potential
+deviates from the Dirac point, the system shows a possible transition from the
+gapped to the gapless phase and switches the corresponding N\'{e}el vector
+configuration. We perform density functional theory calculations to verify our
+analysis using a realistic material and discuss a two terminal transport
+measurement as a possible route to identify the voltage induced switching of
+the N\'{e}el vector.",1711.09926v2
+2017-12-11,Convergent tangent plane integrators for the simulation of chiral magnetic skyrmion dynamics,"We consider the numerical approximation of the Landau-Lifshitz-Gilbert
+equation, which describes the dynamics of the magnetization in ferromagnetic
+materials. In addition to the classical micromagnetic contributions, the energy
+comprises the Dzyaloshinskii-Moriya interaction, which is the most important
+ingredient for the enucleation and the stabilization of chiral magnetic
+skyrmions. We propose and analyze three tangent plane integrators, for which we
+prove (unconditional) convergence of the finite element solutions towards a
+weak solution of the problem. The analysis is constructive and also establishes
+existence of weak solutions. Numerical experiments demonstrate the
+applicability of the methods for the simulation of practically relevant problem
+sizes.",1712.03795v3
+2017-12-31,Proper dissipative torques in antiferromagnetic dynamics,"There is little doubt that the magnetization dynamics of ferromagnetic
+systems is governed by the Landau-Lifshitz-Gilbert equation or its
+generalization with various spin torques. In contrast, there are several sets
+of dynamic equations for two-sublattice antiferromagnets (AFMs) in literature
+that have different forms of dissipative torques and no proper dynamic
+equations for multi-sublattice AFMs and ferrimagnets in general. Here we
+introduce the general Rayleigh dissipation functional into the Lagrange
+equation and derive the proper form of the dissipative torques in the
+phenomenological equations for the AFMs with multiple sublattices. A new type
+of dissipative torque arising from inter-sublattice drag effect is discovered
+that has important influences on magnon lifetime and domain wall motion. In
+particular, our theory unifies different dynamic equations of AFMs in
+literature.",1801.00217v1
+2018-01-12,Optimal Streaming Codes for Channels with Burst and Arbitrary Erasures,"This paper considers transmitting a sequence of messages (a streaming source)
+over a packet erasure channel. In each time slot, the source constructs a
+packet based on the current and the previous messages and transmits the packet,
+which may be erased when the packet travels from the source to the destination.
+Every source message must be recovered perfectly at the destination subject to
+a fixed decoding delay. We assume that the channel loss model introduces either
+one burst erasure or multiple arbitrary erasures in any fixed-sized sliding
+window. Under this channel loss assumption, we fully characterize the maximum
+achievable rate by constructing streaming codes that achieve the optimal rate.
+In addition, our construction of optimal streaming codes implies the full
+characterization of the maximum achievable rate for convolutional codes with
+any given column distance, column span and decoding delay. Numerical results
+demonstrate that the optimal streaming codes outperform existing streaming
+codes of comparable complexity over some instances of the Gilbert-Elliott
+channel and the Fritchman channel.",1801.04241v2
+2018-01-16,Detecting Electron Density Fluctuations from Cosmic Microwave Background Polarization using a Bispectrum Approach,"Recent progress in high sensitivity Cosmic Microwave Background (CMB)
+polarization experiments opens up a window on large scale structure (LSS), as
+CMB polarization fluctuations on small angular scales can arise from a
+combination of LSS and ionization fluctuations in the late universe.
+Gravitational lensing effects can be extracted from CMB datasets with quadratic
+estimators but reconstructions of electron density fluctuations (EDFs) with
+quadratic estimators are found to be significantly biased by the much larger
+lensing effects in the secondary CMB fluctuations. In this paper we establish a
+bispectrum formalism using tracers of LSS to extract the subdominant EDFs from
+CMB polarization data. We find that this bispectrum can effectively reconstruct
+angular band-powers of cross correlation between EDFs and LSS tracers. Next
+generation CMB polarization experiments in conjunction with galaxy surveys and
+cosmic infrared background experiments can detect signatures of EDFs with high
+significance.",1801.05396v1
+2018-01-18,Magpy: A C++ accelerated Python package for simulating magnetic nanoparticle stochastic dynamics,"Magpy is a C++ accelerated Python package for modelling and simulating the
+magnetic dynamics of nano-sized particles. Nanoparticles are modelled as a
+system of three-dimensional macrospins and simulated with a set of coupled
+stochastic differential equations (the Landau-Lifshitz-Gilbert equation), which
+are solved numerically using explicit or implicit methods. The results of the
+simulations may be used to compute equilibrium states, the dynamic response to
+external magnetic fields, and heat dissipation. Magpy is built on a C++
+library, which is optimised for serial execution, and exposed through a Python
+interface utilising an embarrassingly parallel strategy. Magpy is free,
+open-source, and available on github under the 3-Clause BSD License.",1801.06073v2
+2018-01-22,On the List Decodability of Self-orthogonal Rank Metric Codes,"V. Guruswami and N. Resch prove that the list decodability of
+$\mathbb{F}_q$-linear rank metric codes is as good as that of random rank
+metric codes in~\cite{venkat2017}. Due to the potential applications of
+self-orthogonal rank metric codes, we focus on list decoding of them. In this
+paper, we prove that with high probability, an $\F_q$-linear self-orthogonal
+rank metric code over $\mathbb{F}_q^{n\times m}$ of rate
+$R=(1-\tau)(1-\frac{n}{m}\tau)-\epsilon$ is shown to be list decodable up to
+fractional radius $\tau\in(0,1)$ and small $\epsilon\in(0,1)$ with list size
+depending on $\tau$ and $q$ at most $O_{\tau, q}(\frac{1}{\epsilon})$. In
+addition, we show that an $\mathbb{F}_{q^m}$-linear self-orthogonal rank metric
+code of rate up to the Gilbert-Varshamov bound is $(\tau n, \exp(O_{\tau,
+q}(\frac{1}{\epsilon})))$-list decodable.",1801.07033v1
+2018-01-25,Smoothing Algorithms for Computing the Projection onto a Minkowski Sum of Convex Sets,"In this paper, the problem of computing the projection, and therefore the
+minimum distance, from a point onto a Minkowski sum of general convex sets is
+studied. Our approach is based on the minimum norm duality theorem originally
+stated by Nirenberg and the Nesterov smoothing techniques. It is shown that
+projection points onto a Minkowski sum of sets can be represented as the sum of
+points on constituent sets so that, at these points, all of the sets share the
+same normal vector which is the negative of the dual solution. The proposed
+NESMINO algorithm improves the theoretical bound on number of iterations from
+$O(\frac{1}{\epsilon})$ by Gilbert [SIAM J. Contr., vol. 4, pp. 61--80, 1966]
+to $O\left(\frac{1}{\sqrt{\epsilon}}\ln(\frac{1}{\epsilon})\right)$, where
+$\epsilon$ is the desired accuracy for the objective function. Moreover, the
+algorithm also provides points on each component sets such that their sum is
+equal to the projection point.",1801.08285v1
+2018-01-25,Finite momentum Cooper pairing in 3D topological insulator Josephson junctions,"Unconventional superconductivity arising from the interplay between strong
+spin-orbit coupling and magnetism is an intensive area of research. One form of
+unconventional superconductivity arises when Cooper pairs subjected to a
+magnetic exchange coupling acquire a finite momentum. Here, we report on a
+signature of finite momentum Cooper pairing in the 3D topological insulator
+Bi2Se3. We apply in-plane and out-of-plane magnetic fields to proximity-coupled
+Bi2Se3 and find that the in-plane field creates a spatially oscillating
+superconducting order parameter in the junction as evidenced by the emergence
+of an anomalous Fraunhofer pattern. We describe how the anomalous Fraunhofer
+patterns evolve for different device parameters, and we use this to understand
+the microscopic origin of the oscillating order parameter. The agreement
+between the experimental data and simulations shows that the finite momentum
+pairing originates from the coexistence of the Zeeman effect and Aharonov-Bohm
+flux.",1801.08504v1
+2018-01-31,Numerical analytic continuation of Euclidean data,"In this work we present a direct comparison of three different numerical
+analytic continuation methods: the Maximum Entropy Method, the Backus-Gilbert
+method and the Schlessinger point or Resonances Via Pad\'{e} method. First, we
+perform a benchmark test based on a model spectral function and study the
+regime of applicability of these methods depending on the number of input
+points and their statistical error. We then apply these methods to more
+realistic examples, namely to numerical data on Euclidean propagators obtained
+from a Functional Renormalization Group calculation, to data from a lattice
+Quantum Chromodynamics simulation and to data obtained from a tight-binding
+model for graphene in order to extract the electrical conductivity.",1801.10348v2
+2018-02-03,Stochastic dynamics of planar magnetic moments in a three-dimensional environment,"We study the stochastic dynamics of a two-dimensional magnetic moment
+embedded in a three-dimensional environment, described by means of the
+stochastic Landau-Lifshitz-Gilbert (sLLG) equation. We define a covariant
+generalization of this equation, valid in the ""generalized Stratonovich
+discretization prescription"". We present a path integral formulation that
+allows to compute any $n-$point correlation function, independently of the
+stochastic calculus used. Using this formalism, we show the equivalence between
+the cartesian formulation with vectorial noise, with the polar formulation with
+just one scalar fluctuation term. In particular, we show that, for isotropic
+fluctuations, the system is represented by an {\em additive stochastic
+process}, despite of the multiplicative terms appearing in the original
+formulation of the sLLG equation, but, for anisotropic fluctuations the noise
+turns out to be truly multiplicative.",1802.01027v2
+2018-02-07,Asymptotically Locally Euclidean/Kaluza-Klein Stationary Vacuum Black Holes in 5 Dimensions,"We produce new examples, both explicit and analytical, of bi-axisymmetric
+stationary vacuum black holes in 5 dimensions. A novel feature of these
+solutions is that they are asymptotically locally Euclidean in which spatial
+cross-sections at infinity have lens space $L(p,q)$ topology, or asymptotically
+Kaluza-Klein so that spatial cross-sections at infinity are topologically
+$S^1\times S^2$. These are nondegenerate black holes of cohomogeneity 2, with
+any number of horizon components, where the horizon cross-section topology is
+any one of the three admissible types: $S^3$, $S^1\times S^2$, or $L(p,q)$.
+Uniqueness of these solutions is also established. Our method is to solve the
+relevant harmonic map problem with prescribed singularities, having target
+symmetric space $SL(3,\mathbb{R})/SO(3)$. In addition, we analyze the
+possibility of conical singularities and find a large family for which
+geometric regularity is guaranteed.",1802.02457v2
+2018-02-16,A Reallocation Algorithm for Online Split Packing of Circles,"The Split Packing algorithm \cite{splitpacking_ws, splitpackingsoda,
+splitpacking} is an offline algorithm that packs a set of circles into
+triangles and squares up to critical density. In this paper, we develop an
+online alternative to Split Packing to handle an online sequence of insertions
+and deletions, where the algorithm is allowed to reallocate circles into new
+positions at a cost proportional to their areas. The algorithm can be used to
+pack circles into squares and right angled triangles. If only insertions are
+considered, our algorithm is also able to pack to critical density, with an
+amortised reallocation cost of $O(c\log \frac{1}{c})$ for squares, and
+$O(c(1+s^2)\log_{1+s^2}\frac{1}{c})$ for right angled triangles, where $s$ is
+the ratio of the lengths of the second shortest side to the shortest side of
+the triangle, when inserting a circle of area $c$. When insertions and
+deletions are considered, we achieve a packing density of $(1-\epsilon)$ of the
+critical density, where $\epsilon>0$ can be made arbitrarily small, with an
+amortised reallocation cost of $O(c(1+s^2)\log_{1+s^2}\frac{1}{c} +
+c\frac{1}{\epsilon})$.",1802.05873v3
+2018-02-22,Super-Resolution 1H Magnetic Resonance Spectroscopic Imaging utilizing Deep Learning,"Magnetic resonance spectroscopic imaging (SI) is a unique imaging technique
+that provides biochemical information from in vivo tissues. The 1H spectra
+acquired from several spatial regions are quantified to yield metabolite
+concentrations reflective of tissue metabolism. However, since these
+metabolites are found in tissues at very low concentrations, SI is often
+acquired with limited spatial resolution. In this work we test the hypothesis
+that deep learning is able to upscale low resolution SI, together with the
+T1-weighted (T1w) image, to reconstruct high resolution SI. We report a novel
+densely connected Unet (D-Unet) architecture capable of producing
+super-resolution spectroscopic images. The inputs for the D-UNet are the T1w
+image and the low resolution SI image while the output is the high resolution
+SI. The results of the D-UNet are compared both qualitatively and
+quantitatively to simulated and in vivo high resolution SI. It is found that
+this deep learning approach can produce high quality spectroscopic images and
+reconstruct entire 1H spectra from low resolution acquisitions, which can
+greatly advance the current SI workflow.",1802.07909v3
+2018-02-26,Devil's Staircases in SFS Josephson Junctions,"We study the effect of coupling between the superconducting current and
+magnetization in the superconductor/ferromagnet/superconductor Josephson
+junction under an applied circularly polarized magnetic field. Manifestation of
+ferromagnetic resonance in the frequency dependence of the amplitude of the
+magnetization and the average critical current density is demonstrated
+numerically. The IV-characteristics show subharmonic steps that form devil's
+staircases, following a continued fraction algorithm. The origin of the found
+steps is related to the effect of the magnetization dynamics on the phase
+difference in the Josephson junction. The dynamics of our system is described
+by a generalized RCSJ model coupled to the Landau-Lifshitz-Gilbert equation. In
+the suplement we justify analytically the appearance of the fractional steps in
+IV-characteristics of the superconductor/ferromagnet/superconductor Josephson
+junction.",1802.09212v2
+2018-02-26,Controlled creation and stability of kπ-skyrmions on a discrete lattice,"We determine sizes and activation energies of k{\pi}-skyrmions on a discrete
+lattice using the Landau- Lifshitz-Gilbert equation and the geodesic nudged
+elastic band method. The employed atomic material parameters are based on the
+skyrmionic material system Pd/Fe/Ir(111). We find that the critical magnetic
+fields for collapse of the 2{\pi}-skyrmion and 3{\pi}-skyrmion are very close
+to each other and considerably lower than the critical field of the
+1{\pi}-skyrmion. The activation energy protecting the structures does not
+strictly decrease with increasing k as it can be larger for the 3{\pi}-skyrmion
+than for the 2{\pi}-skyrmion depending on the applied magnetic field.
+Furthermore, we propose a method of switching the skyrmion order k by a
+reversion of the magnetic field direction in samples of finite size.",1802.09257v1
+2018-03-14,Subnanosecond magnetization reversal of magnetic nanoparticle driven by chirp microwave field pulse,"We investigate the magnetization reversal of single-domain magnetic
+nanoparticle driven by linear down-chirp microwave magnetic field pulse.
+Numerical simulations based on the Landau-Lifshitz-Gilbert equation reveal that
+solely down-chirp pulse is capable of inducing subnanosecond magnetization
+reversal. With a certain range of initial frequency and chirp rate, the
+required field amplitude is much smaller than that of constant-frequency
+microwave field. The fast reversal is because the down-chirp microwave field
+acts as an energy source and sink for the magnetic particle before and after
+crossing over the energy barrier, respectively. Applying a spin-polarized
+current additively to the system further reduces the microwave field amplitude.
+Our findings provide a new way to realize low-cost and fast magnetization
+reversal.",1803.05261v1
+2018-03-14,Dynamics of distorted skyrmions in strained chiral magnets,"In this work, we study the microscopic dynamics of distorted skyrmions in
+strained chiral magnets [K. Shibata et al., Nat. Nanotech. 10, 589 (2015)]
+under gradient magnetic field or electric current by Landau-Lifshitz-Gilbert
+simulations of the anisotropic spin model. It is observed that the dynamical
+responses are also anisotropic, and the velocities of the distorted skyrmions
+are periodically dependent on the directions of the external stimuli.
+Furthermore, in addition to the uniform motion, our work also demonstrates
+anti-phase harmonic vibrations of the two skyrmions in nanostripes, and the
+frequencies are mainly determined by the exchange anisotropy. The simulated
+results are well explained by Thiele theory, which may provide useful
+information in understanding the dynamics of the distorted skyrmions in
+strained chiral magnets.",1803.05298v1
+2018-03-19,Dynamics and Stability of Meshed Multiterminal HVDC Networks,"This paper investigates the existence of an equilibrium point in
+multiterminal HVDC (MT-HVDC) grids, assesses its uniqueness and defines
+conditions to ensure its stability. An offshore MT-HVDC system including two
+wind farms is selected as application test case. At first, a generalized
+dynamic model of the network is proposed, using hypergraph theory. Such model
+captures the frequency dependence of transmission lines and cables, it is
+non-linear due to the constant power behavior of the converter terminals using
+droop regulation, and presents a suitable degree of simplifications of the MMC
+converters, under given conditions, to allow system level studies over
+potentially large networks. Based on this model, the existence and uniqueness
+of the equilibrium point is demonstrated by returning the analysis to a
+load-flow problem and using the Banach fixed point theorem. Additionally, the
+stability of the equilibrium is analyzed by obtaining a Lyapunov function by
+the Krasovskii's theorem. Computational results obtained for the selected 4
+terminals MT-HVDC grid corroborate the requirement for the existence and
+stability of the equilibrium point.",1803.06892v2
+2018-03-16,Motion of vortices in ferromagnetic spin-1 BEC,"The paper investigates dynamics of nonsingular vortices in a ferromagnetic
+spin-1 BEC, where spin and mass superfluidity coexist in the presence of
+uniaxial anisotropy (linear and quadratic Zeeman effect). The analysis is based
+on hydrodynamics following from the Gross-Pitaevskii theory. Cores of
+nonsingular vortices are skyrmions with charge, which is tuned by uniaxial
+anisotropy and can have any fractal value between 0 and 1. There are
+circulations of mass and spin currents around these vortices. The results are
+compared with the equation of vortex motion derived earlier in the
+Landau-Lifshitz-Gilbert theory for magnetic vortices in easy-plane
+ferromagnetic insulators. In the both cases the transverse gyrotropic force
+(analog of the Magnus force in superfluid and classical hydrodynamics) is
+proportional to the charge of skyrmions in vortex cores.",1803.06939v1
+2018-03-22,Mapping ideals of quantum group multipliers,"We study the dual relationship between quantum group convolution maps
+$L^1(\mathbb{G})\rightarrow L^{\infty}(\mathbb{G})$ and completely bounded
+multipliers of $\widehat{\mathbb{G}}$. For a large class of locally compact
+quantum groups $\mathbb{G}$ we completely isomorphically identify the mapping
+ideal of row Hilbert space factorizable convolution maps with
+$M_{cb}(L^1(\widehat{\mathbb{G}}))$, yielding a quantum Gilbert representation
+for completely bounded multipliers. We also identify the mapping ideals of
+completely integral and completely nuclear convolution maps, the latter case
+coinciding with $\ell^1(\widehat{b\mathbb{G}})$, where $b\mathbb{G}$ is the
+quantum Bohr compactification of $\mathbb{G}$. For quantum groups whose dual
+has bounded degree, we show that the completely compact convolution maps
+coincide with $C(b\mathbb{G})$. Our techniques comprise a mixture of operator
+space theory and abstract harmonic analysis, including Fubini tensor products,
+the non-commutative Grothendieck inequality, quantum Eberlein
+compactifications, and a suitable notion of quasi-SIN quantum group, which we
+introduce and exhibit examples from the bicrossed product construction. Our
+main results are new even in the setting of group von Neumann algebras $VN(G)$
+for quasi-SIN locally compact groups $G$.",1803.08342v2
+2018-03-28,Low-temperature ageing of zirconia-toughened alumina ceramics and its implication in biomedical implants,"Changes in crystalline phases resulting from low-temperature ageing of
+different yttria doped and non-doped zirconia-toughened alumina composites and
+nanocomposites were investigated under controlled humidity and temperature
+conditions in autoclave. A classical powder mixing processing route and a new
+modified colloidal processing route were used to process the composites.
+Different compositions ranging from 2.5 wt.% zirconia in a matrix of alumina to
+pure zirconia (3Y-TZP) were studied. It was observed that Al2O3+yttria
+stabilised ZrO2 composites exhibited significant ageing. However, ageing was
+much slower than traditionally observed for Y-TZP ceramics, due to the presence
+of the alumina matrix. Ageing was clearly limited for zirconia content beyond
+25 wt.%. On the other side of the spectrum, Al2O3+2.5 wt.% ZrO2 initially
+presented a monoclinic fraction but did not show any ageing degradation. These
+composites seem to represent the best choice between slow crack growth and
+ageing resistance.",1803.10465v1
+2018-03-28,Accelerated Aging in 3 mol%-Yttria-Stabilized Tetragonal Zirconia Ceramics Sintered in Reducing Conditions,"The aging behavior of 3-mol%-yttria-stabilized tetragonal zirconia (3Y-TZP)
+ceramics sintered in air and in reducing conditions was investigated at
+140{\deg}C in water vapor. It was observed by X-ray diffraction (XRD) that
+3Y-TZP samples sintered in reducing conditions exhibited significantly higher
+tetragonal-to-monoclinic transformation than samples with similar density and
+average grain size values but obtained by sintering in air. This fact is
+explained by the increase of the oxygen vacancy concentration and by the
+presence at the grain boundary region of a new aggregate phase formed because
+of the exolution of Fe2+ ions observed by X-ray photoelectron spectroscopy.",1803.10580v1
+2018-03-30,Atomic force microscopy study of the surface degradation mechanisms of zirconia based ceramics,"Atomic force microscopy (AFM) can be used to characterise several aspects of
+the surface degradation and reinforcement mechanisms of zirconia based
+ceramics, such as crack propagation, martensitic relief formation, grains
+pull-out and transformation toughening. AFM can also be used to quantify
+precisely the transformation and provide reliable parameters for long term
+degradation prediction. In particular, the tetragonal to monoclinic (t-m) phase
+transformation of zirconia has been the object of extensive investigations of
+the last twenty years, and is now recognised as being of martensitic nature.
+New strong evidences supporting the martensitic nature of the transformation
+are reported here. These observations, considering their scale and precision,
+are a new step toward the understanding of the t-m phase transformation of
+zirconia and related degradation mechanisms.",1804.00002v1
+2018-04-05,Stochastic ferrimagnetic Landau-Lifshitz-Bloch equation for finite magnetic structures,"Precise modeling of the magnetization dynamics of nanoparticles with finite
+size effects at fast varying temperatures is a computationally challenging
+task. Based on the Landau-Lifshitz-Bloch (LLB) equation we derive a coarse
+grained model for disordered ferrimagnets, which is both fast and accurate.
+First, we incorporate stochastic fluctuations to the existing ferrimagnetic LLB
+equation. Further, we derive a thermodynamic expression for the temperature
+dependent susceptibilities, which is essential to model finite size effects.
+Together with the zero field equilibrium magnetization the susceptibilities are
+used in the stochastic ferrimagnetic LLB to simulate a $5\times10$ nm$^2$
+ferrimagnetic GdFeCo particle with 70 % FeCo and 30 % Gd under various external
+applied fields and heat pulses. The obtained trajectories agree well with those
+of an atomistic model, which solves the stochastic Landau-Lifshitz-Gilbert
+equation for each atom. Additionally, we derive an expression for the
+intergrain exchange field which couple the ferromagnetic sublattices of a
+ferrimagnet. A comparison of the magnetization dynamics obtained from this
+simpler model with those of the ferrimagnetic LLB equation shows a perfect
+agreement.",1804.01724v1
+2018-04-06,Temperature dependence of bulk viscosity within lattice simulation of $SU(3)$--gluodynamics,"In this paper the temperature dependence of the $SU(3)$--gluodynamics bulk
+viscosity is studied within lattice simulations. To carry out this study we
+measure the correlation function of the trace of the energy-momentum tensor for
+a set of temperatures within the range $T/T_c \in (0.9, 1.5)$. To extract the
+bulk viscosity from the correlation function we apply the Backus-Gilbert method
+and the Tikhonov regularization method. We show that the ratio $\zeta/s$ is
+small in the region $T/T_c \geqslant 1.1-1.2$ and in the vicinity of the
+transition $T/T_c \leqslant 1.1-1.2$ it quickly rises. Our results are in
+agreement with previous lattice studies and in a reasonable agreement with
+other phenomenological approaches. Obtained values of the bulk viscosity are
+significantly larger than perturbative results, what confirms that QGP is a
+strongly correlated system.",1804.02382v2
+2018-04-16,Anisotropy of exchange stiffness based on atomic-scale magnetic properties in rare-earth permanent magnet Nd$_2$Fe$_{14}$B,"We examine the anisotropic properties of the exchange stiffness constant,
+$\mathcal{A}$, for rare-earth permanent magnet, Nd$_2$Fe$_{14}$B, by connecting
+analyses with two different scales of length, i.e., Monte Carlo (MC) method
+with an atomistic spin model and Landau-Lifshitz-Gilbert (LLG) equation with a
+continuous magnetic model. The atomistic MC simulations are performed on the
+spin model of Nd$_2$Fe$_{14}$B constructed from ab-initio calculations, and the
+LLG micromagnetics simulations are performed with the parameters obtained by
+the MC simulations. We clarify that the amplitude and the thermal property of
+$\mathcal{A}$ depend on the orientation in the crystal, which are attributed to
+the layered structure of Nd atoms and weak exchange couplings between Nd and Fe
+atoms. We also confirm that the anisotropy of $\mathcal{A}$ significantly
+affects the threshold field for the magnetization reversal (coercivity) given
+by the depinning process.",1804.05824v2
+2018-03-29,Percolative Mechanism of Aging in Zirconia-Containing Ceramics for Medical Applications,"Recently, several episodes of fracture of zirconia ceramic femoral heads of
+total hip prostheses have alarmed the medical and scientific community
+regarding aging problems in zirconia prostheses. Such fractures cause immediate
+local tissue reactions, which require urgent medical intervention to prevent
+further complications. As a result, it has been promoted that yttria-stabilized
+zirconia (Y-TZP) hip prostheses be substituted by alumina and alumina/Y-TZP
+ceramics. In the present investigation, we have found an upper limit of Y-TZP
+concentration in alumina/Y-TZP composites (16 vol.%) to avoid future aging
+problems. This limit coincides with the percolation threshold measured by
+infrared (IR) reflectance in a series of alumina/Y-TZP composites.",1804.08696v1
+2018-03-30,Reliability assessment in advanced nanocomposite materials for orthopaedic applications,"Alumina-zirconia nano-composites were recently developed as alternative
+bearing materials for orthopedics. Previous, preliminary reports show that such
+alumina-zirconia nanocomposites exhibit high crack resistance and low wear
+rate. In this paper, additional information is given in terms of wear, crack
+resistance and ageing behaviour: femoral heads are inspected after 7 million
+cycles of wear testing on a hip simulator, crack resistance is measured and
+compared to other ceramics used today in orthopedics, slow crack growth is
+reported under static and cyclic fatigue, and aging resistance is assessed. We
+also report on the load to failure of femoral heads prototypes during
+compression tests. This overall reliability assessment ensures a potential
+future development for these kinds of new nanocomposites in the orthopedic
+field.",1804.08702v1
+2018-04-26,Shape of a skyrmion,"We propose a method of determining the shape of a two-dimensional magnetic
+skyrmion, which can be parameterized as the position dependence of the
+orientation of the local magnetic moment, by using the expansion in terms of
+the eigenfunctions of the Schr\""{o}dinger equation of a harmonic oscillator. A
+variational calculation is done, up to the next-to-next-to-leading order. This
+result is verified by a lattice simulation based on Landau-Lifshitz-Gilbert
+equation. Our method is also applied to the dissipative matrix in the Thiele
+equation as well as two interacting skyrmions in a bilayer system.",1804.10162v3
+2018-04-30,Modular Compact Modeling of Magnetic Tunnel Junction Devices,"This paper describes a robust, modular, and physics- based circuit framework
+to model conventional and emerging Magnetic Tunnel Junction (MTJ) devices.
+Magnetization dynamics are described by the stochastic Landau-Lifshitz-Gilbert
+(sLLG) equation whose results are rigorously benchmarked with a Fokker-Planck
+Equation (FPE) description of magnet dynamics. We then show how sLLG is coupled
+to transport equations of MTJ-based devices in a unified circuit platform. Step
+by step, we illustrate how the physics-based MTJ model can be extended to
+include different spintronics phenomena, including spin-transfer-torque (STT),
+voltage-control of magnetic anisotropy (VCMA) and spin-orbit torque (SOT)
+phenomena by experimentally benchmarked examples. To demonstrate how our
+approach can be used in the exploration of novel MTJ-based devices, we also
+present a recently proposed MEMS resonator- driven spin-torque nano oscillator
+(STNO) that can reduce the phase noise of STNOs. We briefly elaborate on the
+use of our framework beyond conventional devices.",1805.00066v2
+2018-05-22,Loss of Hall Conductivity Quantization in a Non-Hermitian Quantum Anomalous Hall Insulator,"Recent work has extended topological band theory to open, non-Hermitian
+Hamiltonians, yet little is understood about how non-Hermiticity alters the
+topological quantization of associated observables. We address this problem by
+studying the quantum anomalous Hall effect (QAHE) generated in the Dirac
+surface states of a 3D time-reversal-invariant topological insulator (TI) that
+is proximity-coupled to a metallic ferromagnet. By constructing a contact
+self-energy for the ferromagnet, we show that in addition to generating a mass
+gap in the surface spectrum, the ferromagnet can introduce a non-Hermitian
+broadening term, which can obscure the mass gap in the spectral function. We
+calculate the Hall conductivity for the effective non-Hermitian Hamiltonian
+describing the heterostructure and show that it is no longer quantized despite
+being classified as a Chern insulator based on non-Hermitian topological band
+theory. Our results indicate that the QAHE will be challenging to
+experimentally observe in ferromagnet-TI heterostructures due to the finite
+lifetime of quasi-particles at the interface.",1805.08892v2
+2018-05-31,Spin-orbit torque induced dipole skyrmion motion at room temperature,"We demonstrate deterministic control of dipole-field-stabilized skyrmions by
+means of spin-orbit torques arising from heavy transition-metal seed layers.
+Experiments are performed on amorphous Fe/Gd multilayers that are patterned
+into wires and exhibit stripe domains and dipole skyrmions at room temperature.
+We show that while the domain walls and skyrmions are achiral on average due to
+lack of Dzyaloshinskii-Moriya interactions, the N\'eel-like closure domain
+walls at each surface are chiral and can couple to spin-orbit torques. The
+current-induced domain evolutions are reported for different magnetic phases,
+including disordered stripe domains, coexisting stripes and dipole skyrmions
+and a closed packed dipole skyrmion lattice. The magnetic textures exhibit
+motion under current excitations with a current density ~10^8 A/m2. By
+comparing the motion resulting from magnetic spin textures in Fe/Gd films with
+different heavy transition-metal interfaces, we confirm spin currents can be
+used to manipulate achiral dipole skyrmions via spin-orbit torques.",1805.12517v1
+2018-06-11,Geometric Lagrangian averaged Euler-Boussinesq and primitive equations,"In this article we derive the equations for a rotating stratified fluid
+governed by inviscid Euler-Boussinesq and primitive equations that account for
+the effects of the perturbations upon the mean. Our method is based on the
+concept of geometric generalized Lagrangian mean recently introduced by Gilbert
+and Vanneste, combined with generalized Taylor and horizontal isotropy of
+fluctuations as turbulent closure hypotheses. The models we obtain arise as
+Euler-Poincar\'{e} equations and inherit from their parent systems conservation
+laws for energy and potential vorticity. They are structurally and
+geometrically similar to Euler-Boussinesq-$\alpha$ and primitive
+equations-$\alpha$ models, however feature a different regularizing second
+order operator.",1806.05053v2
+2018-06-14,Topological quantization of the flow of magnetic skyrmions driven by a ratchet-like potential under thermal fluctuations,"We consider a magnetic skyrmion adiabatically driven by a spin-polarized
+electrical current periodic in both space and time and asymmetric in space, and
+also subject to a random magnetic field representing the thermal fluctuations.
+We show that when the random magnetic field is low enough, while the time
+variation of the driving current is slow enough, the skyrmion flow is an
+integer multiply of the ratio between the space and time periods, the integer
+being a topological invariant called Chern number. This result is also
+demonstrated by numerically solving the stochastic Landau-Lifshitz-Gilbert
+(sLLG) and Langevin equations. Our work suggests a novel method of manipulating
+skyrmions with topological stability.",1806.05354v1
+2018-06-17,Skyrmion Formation Induced by Antiferromagnetic-enhanced Interfacial Dzyaloshinskii Moriya Interaction,"Ne\'el skyrmions originate from interfacial Dzyaloshinskii Moriya interaction
+(DMI). Recent studies have explored using ferromagnet to host Ne\'el skyrmions
+for device applications. However, challenges remain to reduce the size of
+skyrmion to near 10 nm. Amorphous rare-earth-transitional-metal ferrimagnets
+are attractive alternative materials to obtain ultrasmall skyrmions at room
+temperature. Their intrinsic perpendicular magnetic anisotropy and tunable
+magnetization provides a favorable environment for skyrmion stability. In this
+work, we employ atomistic stochastic Landau-Liftshitz-Gilbert (LLG) algorithm
+to investigate skyrmions in GdFe within the interfacial DMI model. Despite the
+rapid decay of DMI away from the interface, small skyrmions of near 10 nm are
+found in thick ~ 5 nm amorphous GdFe film at 300K. We have also considered
+three scenarios for the sign of DMI between Gd-Fe pair. It is revealed that
+antiferromagnetic coupling in the ferrimagnet plays an important role in
+enhancing the effect of interfacial DMI and to stabilize skyrmion. These
+results show that ferrimagnets and antiferromagnets with intrinsic
+antiferromagnetic couplings are appealing materials to host small skyrmions at
+room temperature, which is crucial to improve density and energy efficiency in
+skyrmion based devices.",1806.06334v1
+2018-06-17,Property Testing for Differential Privacy,"We consider the problem of property testing for differential privacy: with
+black-box access to a purportedly private algorithm, can we verify its privacy
+guarantees? In particular, we show that any privacy guarantee that can be
+efficiently verified is also efficiently breakable in the sense that there
+exist two databases between which we can efficiently distinguish. We give lower
+bounds on the query complexity of verifying pure differential privacy,
+approximate differential privacy, random pure differential privacy, and random
+approximate differential privacy. We also give algorithmic upper bounds. The
+lower bounds obtained in the work are infeasible for the scale of parameters
+that are typically considered reasonable in the differential privacy
+literature, even when we suppose that the verifier has access to an (untrusted)
+description of the algorithm. A central message of this work is that verifying
+privacy requires compromise by either the verifier or the algorithm owner.
+Either the verifier has to be satisfied with a weak privacy guarantee, or the
+algorithm owner has to compromise on side information or access to the
+algorithm.",1806.06427v2
+2018-06-25,Coupled Wire Models of Interacting Dirac Nodal Superconductors,"Topological nodal superconductors possess gapless low energy excitations that
+are characterized by point or line nodal Fermi surfaces. In this work, using a
+coupled wire construction, we study topological nodal superconductors that have
+protected Dirac nodal points. In this construction, the low-energy electronic
+degrees of freedom are confined in a three dimensional array of wires, which
+emerge as pairing vortices of a microscopic superconducting system. The vortex
+array harbors an antiferromagnetic time-reversal and a mirror glide symmetry
+that protect the massless Dirac fermion in the single-body non-interacting
+limit. Within this model, we demonstrate exact-solvable many-body interactions
+that preserve the underlying symmetries and introduce a finite excitation
+energy gap. These gapping interactions support fractionalization and
+generically lead to non-trivial topological order. We also construct a special
+case of $N=16$ Dirac fermions where corresponding the gapping interaction leads
+to a trivial $E_8$ topological order that is closely related to the
+cancellation of the large gravitational anomaly.",1806.09599v1
+2018-07-02,A Broader View on Bias in Automated Decision-Making: Reflecting on Epistemology and Dynamics,"Machine learning (ML) is increasingly deployed in real world contexts,
+supplying actionable insights and forming the basis of automated
+decision-making systems. While issues resulting from biases pre-existing in
+training data have been at the center of the fairness debate, these systems are
+also affected by technical and emergent biases, which often arise as
+context-specific artifacts of implementation. This position paper interprets
+technical bias as an epistemological problem and emergent bias as a dynamical
+feedback phenomenon. In order to stimulate debate on how to change machine
+learning practice to effectively address these issues, we explore this broader
+view on bias, stress the need to reflect on epistemology, and point to
+value-sensitive design methodologies to revisit the design and implementation
+process of automated decision-making systems.",1807.00553v2
+2018-07-06,Spin-torque-induced magnetization dynamics in ferrimagnets based on Landau-Lifshitz-Bloch Equation,"A theoretical model based on the Landau-Lifshitz-Bloch equation is developed
+to study the spin-torque effect in ferrimagnets. Experimental findings, such as
+the temperature dependence, the peak in spin torque, and the angular-momentum
+compensation, can be well captured. In contrast to the ferromagnet system, the
+switching trajectory in ferrimagnets is found to be precession free. The two
+sublattices are not always collinear, which produces large exchange field
+affecting the magnetization dynamics. The study of material composition shows
+the existence of an oscillation region at intermediate current density, induced
+by the nondeterministic switching. Compared to the Landau-Lifshitz-Gilbert
+model, our developed model based on the Landau-Lifshitz-Bloch equation enables
+the systematic study of spin-torque effect and the evaluation of
+ferrimagnet-based devices.",1807.02445v1
+2018-07-10,Plumbing Constructions and the Domain of Outer Communication for 5-Dimensional Stationary Black Holes,"The topology of the domain of outer communication for 5-dimensional
+stationary bi-axisymmetric black holes is classified in terms of disc bundles
+over the 2-sphere and plumbing constructions. In particular we find an
+algorithmic bijective correspondence between the plumbing of disc bundles and
+the rod structure formalism for such spacetimes. Furthermore, we describe a
+canonical fill-in for the black hole region and cap for the asymptotic region.
+The resulting compactified domain of outer communication is then shown to be
+homeomorphic to $S^4$, a connected sum of $S^2\times S^2$'s, or a connected sum
+of complex projective planes $\mathbb{CP}^2$. Combined with recent existence
+results, it is shown that all such topological types are realized by vacuum
+solutions. In addition, our methods treat all possible types of asymptotic
+ends, including spacetimes which are asymptotically flat, asymptotically
+Kaluza-Klein, or asymptotically locally Euclidean.",1807.03452v1
+2018-07-13,Deep Learning in the Wild,"Deep learning with neural networks is applied by an increasing number of
+people outside of classic research environments, due to the vast success of the
+methodology on a wide range of machine perception tasks. While this interest is
+fueled by beautiful success stories, practical work in deep learning on novel
+tasks without existing baselines remains challenging. This paper explores the
+specific challenges arising in the realm of real world tasks, based on case
+studies from research \& development in conjunction with industry, and extracts
+lessons learned from them. It thus fills a gap between the publication of
+latest algorithmic and methodical developments, and the usually omitted
+nitty-gritty of how to make them work. Specifically, we give insight into deep
+learning projects on face matching, print media monitoring, industrial quality
+control, music scanning, strategy game playing, and automated machine learning,
+thereby providing best practices for deep learning in practice.",1807.04950v1
+2018-07-16,Digital frequency multiplexing with sub-Kelvin SQUIDs,"Digital frequency multiplexing (dfMux) is a readout architecture for
+transition edge sensor-based detector arrays and is used on telescopes
+including SPT-3G, POLARBEAR-2, and LiteBIRD. Here, we present recent progress
+and plans for development of a sub-Kelvin SQUID architecture for digital
+frequency multiplexed bolometers. This scheme moves the SQUID from the 4 K
+stage to the 250 mK stage, adjacent to the bolometers. Operating the SQUID on
+the detector stage may offer lower noise and greater scalability. Electrical
+performance will be improved as a result of decreased wiring length and reduced
+parasitics, allowing for higher multiplexing factors and lower bolometer
+R_normal . These performance improvements will enable ultra-large focal planes
+for future instruments such as CMB-S4.",1807.05995v1
+2018-07-20,Sphinx: a massively multiplexed fiber positioner for MSE,"In this paper we present the Australian Astronomical Observatory's concept
+design for Sphinx - a fiber positioned with 4332 spines on a 7.77mm pitch for
+CFHT's Mauna Kea Spectroscopic Explorer (MSE) Telescope. Based on the Echidna
+technology used with FMOS (on Subaru) and 4MOST (on VISTA), the next evolution
+of the tilting spine design delivers improved performance and superior
+allocation efficiency. Several prototypes have been constructed that
+demonstrate the suitability of the new design for MSE. Results of prototype
+testing are presented, along with an analysis of the impact of tilting spines
+on the overall survey efficiency. The Sphinx fiber positioned utilizes a novel
+metrology system for spine position feedback. The metrology design and the
+careful considerations required to achieve reliable, high accuracy measurements
+of all fibres in a realistic telescope environment are also presented.",1807.09181v1
+2018-07-30,Graphs admitting only constant splines,"We study {\em generalized graph splines,} introduced by Gilbert, Viel, and
+the last author. For a large class of rings, we characterize the graphs that
+only admit constant splines. To do this, we prove that if a graph has a
+particular type of cutset (e.g., a bridge), then the space of splines naturally
+decomposes as a certain direct sum of submodules. As an application, we use
+these results to describe splines on a triangulation studied by Zhou and Lai,
+but over a different ring than they used.",1807.11515v2
+2018-08-05,Searching for patchy reionization from cosmic microwave background with hybrid quadratic estimators,"We propose a hybrid quadratic estimator to measure cross correlations between
+gravitational lensing of the cosmic microwave background (CMB) and differential
+screening effects arising from fluctuations in the electron column density,
+such as could arise from patchy reionization. The hybrid quadratic estimators
+are validated by simulated data sets with both Planck and CMB-Stage 4 (CMB-S4)
+instrumental properties and found to be able to recover the cross-power spectra
+with almost no biases. We apply this technique to Planck 2015 temperature data
+and obtain cross-power spectra between gravitational lensing and differential
+screening effects. Planck data alone cannot detect the
+patchy-reionization-induced cross-power spectrum but future experiment like
+CMB-S4 will be able to robustly measure the expected signal and deliver new
+insights on reionization.",1808.01592v1
+2018-08-08,"Revisiting Gilbert Strang's ""A Chaotic Search for $i$""","In the paper ""A Chaotic Search for $i$""~(\cite{strang1991chaotic}), Strang
+completely explained the behaviour of Newton's method when using real initial
+guesses on $f(x) = x^{2}+1$, which has only a pair of complex roots $\pm i$. He
+explored an exact symbolic formula for the iteration, namely $x_{n}=\cot{
+\left( 2^{n} \theta_{0} \right) }$, which is valid in exact arithmetic. In this
+paper, we extend this to to $k^{th}$ order Householder methods, which include
+Halley's method, and to the secant method. Two formulae, $x_{n}=\cot{ \left(
+\theta_{n-1}+\theta_{n-2} \right) }$ with
+$\theta_{n-1}=\mathrm{arccot}{\left(x_{n-1}\right)}$ and
+$\theta_{n-2}=\mathrm{arccot}{\left(x_{n-2}\right)}$, and $x_{n}=\cot{ \left(
+(k+1)^{n} \theta_{0} \right) }$ with $\theta_{0} = \mathrm{arccot}(x_{0})$, are
+provided. The asymptotic behaviour and periodic character are illustrated by
+experimental computation. We show that other methods (Schr\""{o}der iterations
+of the first kind) are generally not so simple. We also explain an old method
+that can be used to allow Maple's \textsl{Fractals[Newton]} package to
+visualize general one-step iterations by disguising them as Newton iterations.",1808.03229v1
+2018-08-11,Micromagnetic modeling of Terahertz oscillations in an antiferromagnetic material driven by spin-Hall effect,"The realization of THz sources is a fundamental aspect for a wide range of
+applications. Over different approaches, compact THz oscillators can be
+realized taking advantage of dynamics in antiferromagnetic (AFMs) thin films
+driven by spin-Hall effect. Here we perform a systematic study of these THz
+oscillators within a full micromagnetic solver based on the numerical solution
+of two coupled Landau-Lifshitz-Gilbert-Slonczewski equations, for the case of
+ultra-thin films, i.e. when the N\'eel temperature of an AFM is substantially
+reduced. We have found two different dynamical modes depending on the strength
+of the Dzyaloshinskii-Moriya interaction (DMI). At low DMI, a large amplitude
+precession is excited where both the magnetizations of the sublattices are in a
+uniform state and rotate in the same direction. At large enough DMI, the ground
+state of the AFM becomes non-uniform and the antiferromagnetic dynamics is
+characterized by ultrafast domain wall motion.",1808.03773v1
+2018-08-30,Iterative solution and preconditioning for the tangent plane scheme in computational micromagnetics,"The tangent plane scheme is a time-marching scheme for the numerical solution
+of the nonlinear parabolic Landau-Lifshitz-Gilbert equation (LLG), which
+describes the time evolution of ferromagnetic configurations. Exploiting the
+geometric structure of LLG, the tangent plane scheme requires only the solution
+of one linear variational form per time-step, which is posed in the discrete
+tangent space determined by the nodal values of the current magnetization. We
+develop an effective solution strategy for the arising constrained linear
+systems, which is based on appropriate Householder reflections. We derive
+possible preconditioners, which are (essentially) independent of the time-step,
+and prove that the preconditioned GMRES algorithm leads to linear convergence.
+Numerical experiments underpin the theoretical findings.",1808.10281v1
+2018-09-12,Iterative Delegations in Liquid Democracy with Restricted Preferences,"In this paper, we study liquid democracy, a collective decision making
+paradigm which lies between direct and representative democracy. One main
+feature of liquid democracy is that voters can delegate their votes in a
+transitive manner so that: A delegates to B and B delegates to C leads to A
+delegates to C. Unfortunately, this process may not converge as there may not
+even exist a stable state (also called equilibrium). In this paper, we
+investigate the stability of the delegation process in liquid democracy when
+voters have restricted types of preference on the agent representing them
+(e.g., single-peaked preferences). We show that various natural structures of
+preferences guarantee the existence of an equilibrium and we obtain both
+tractability and hardness results for the problem of computing several
+equilibria with some desirable properties.",1809.04362v2
+2018-09-25,Phase change materials for nano-polaritonics: a case study of hBN/VO2 heterostructures,"Polaritonic excitation and control in van der Waals (vdW) materials exhibit
+superior merits than conventional materials and thus hold new promise for
+exploring light matter interactions. In this work, we created vdW
+heterostructures combining hexagonal boron nitride (hBN) and a representative
+phase change material - vanadium dioxide (VO2). Using infrared
+nano-spectroscopy and nano-imaging, we demonstrated the dynamic tunability of
+hyperbolic phonon polaritons in hBN/VO2 heterostructures by temperature control
+in a precise and reversible fashion. The dynamic tuning of the polaritons stems
+from the change of local dielectric properties of the VO2 sublayer through
+insulator to metal transition by the temperature control. The high
+susceptibility of polaritons to electronic phase transitions opens
+possibilities for applications of vdW materials in combination with correlated
+phase change materials.",1809.09652v1
+2018-10-08,Causal isotonic regression,"In observational studies, potential confounders may distort the causal
+relationship between an exposure and an outcome. However, under some
+conditions, a causal dose-response curve can be recovered using the
+G-computation formula. Most classical methods for estimating such curves when
+the exposure is continuous rely on restrictive parametric assumptions, which
+carry significant risk of model misspecification. Nonparametric estimation in
+this context is challenging because in a nonparametric model these curves
+cannot be estimated at regular rates. Many available nonparametric estimators
+are sensitive to the selection of certain tuning parameters, and performing
+valid inference with such estimators can be difficult. In this work, we propose
+a nonparametric estimator of a causal dose-response curve known to be monotone.
+We show that our proposed estimation procedure generalizes the classical
+least-squares isotonic regression estimator of a monotone regression function.
+Specifically, it does not involve tuning parameters, and is invariant to
+strictly monotone transformations of the exposure variable. We describe
+theoretical properties of our proposed estimator, including its irregular limit
+distribution and the potential for doubly-robust inference. Furthermore, we
+illustrate its performance via numerical studies, and use it to assess the
+relationship between BMI and immune response in HIV vaccine trials.",1810.03269v2
+2018-10-10,On the Approximation Properties of Random ReLU Features,"We study the approximation properties of random ReLU features through their
+reproducing kernel Hilbert space (RKHS). We first prove a universality theorem
+for the RKHS induced by random features whose feature maps are of the form of
+nodes in neural networks. The universality result implies that the random ReLU
+features method is a universally consistent learning algorithm. We prove that
+despite the universality of the RKHS induced by the random ReLU features,
+composition of functions in it generates substantially more complicated
+functions that are harder to approximate than those functions simply in the
+RKHS. We also prove that such composite functions can be efficiently
+approximated by multi-layer ReLU networks with bounded weights. This depth
+separation result shows that the random ReLU features models suffer from the
+same weakness as that of shallow models. We show in experiments that the
+performance of random ReLU features is comparable to that of random Fourier
+features and, in general, has a lower computational cost. We also demonstrate
+that when the target function is the composite function as described in the
+depth separation theorem, 3-layer neural networks indeed outperform both random
+ReLU features and 2-layer neural networks.",1810.04374v3
+2018-10-15,ABACUS: Unsupervised Multivariate Change Detection via Bayesian Source Separation,"Change detection involves segmenting sequential data such that observations
+in the same segment share some desired properties. Multivariate change
+detection continues to be a challenging problem due to the variety of ways
+change points can be correlated across channels and the potentially poor
+signal-to-noise ratio on individual channels. In this paper, we are interested
+in locating additive outliers (AO) and level shifts (LS) in the unsupervised
+setting. We propose ABACUS, Automatic BAyesian Changepoints Under Sparsity, a
+Bayesian source separation technique to recover latent signals while also
+detecting changes in model parameters. Multi-level sparsity achieves both
+dimension reduction and modeling of signal changes. We show ABACUS has
+competitive or superior performance in simulation studies against
+state-of-the-art change detection methods and established latent variable
+models. We also illustrate ABACUS on two real application, modeling genomic
+profiles and analyzing household electricity consumption.",1810.06167v1
+2018-10-24,Photoinduced topological spin texture in a metallic ferromagnet,"Photoinduced nonequilibrium spin structure is examined in the double-exchange
+model, in which itinerant electrons couple with localized spins through the
+ferromagnetic Hund coupling. In particular, we focus on the transient spin
+structure from the initial ferromagnetic metallic state to the steady
+antiferromagnetic ordered state reported in [Phys. Rev. Lett. 119, 207202
+(2017)]. By solving the Schr\""odinger equation combined with the
+Landau-Lifshitz-Gilbert equation, we find finite winding number and chirality,
+which implies emergence of topological chiral spin textures. These observations
+are reproduced by a calculation where spin dynamics after sudden quench of the
+chemical potential are examined in larger clusters. A possible mechanism of the
+topological spin texture in the transient dynamics is discussed.",1810.10244v1
+2018-11-01,Spatial Functional Linear Model and its Estimation Method,"The classical functional linear regression model (FLM) and its extensions,
+which are based on the assumption that all individuals are mutually
+independent, have been well studied and are used by many researchers. This
+independence assumption is sometimes violated in practice, especially when data
+with a network structure are collected in scientific disciplines including
+marketing, sociology and spatial economics. However, relatively few studies
+have examined the applications of FLM to data with network structures. We
+propose a novel spatial functional linear model (SFLM), that incorporates a
+spatial autoregressive parameter and a spatial weight matrix into FLM to
+accommodate spatial dependencies among individuals. The proposed model is
+relatively flexible as it takes advantage of FLM in handling high-dimensional
+covariates and spatial autoregressive (SAR) model in capturing network
+dependencies. We develop an estimation method based on functional principal
+component analysis (FPCA) and maximum likelihood estimation. Simulation studies
+show that our method performs as well as the FPCA-based method used with FLM
+when no network structure is present, and outperforms the latter when network
+structure is present. A real weather data is also employed to demonstrate the
+utility of the SFLM.",1811.00314v1
+2018-11-12,New Theoretical Bounds and Constructions of Permutation Codes under Block Permutation Metric,"Permutation codes under different metrics have been extensively studied due
+to their potentials in various applications. Generalized Cayley metric is
+introduced to correct generalized transposition errors, including previously
+studied metrics such as Kendall's $\tau$-metric, Ulam metric and Cayley metric
+as special cases. Since the generalized Cayley distance between two
+permutations is not easily computable, Yang et al. introduced a related metric
+of the same order, named the block permutation metric. Given positive integers
+$n$ and $d$, let $\mathcal{C}_{B}(n,d)$ denote the maximum size of a
+permutation code in $S_n$ with minimum block permutation distance $d$. In this
+paper, we focus on the theoretical bounds of $\mathcal{C}_{B}(n,d)$ and the
+constructions of permutation codes under block permutation metric. Using a
+graph theoretic approach, we improve the Gilbert-Varshamov type bound by a
+factor of $\Omega(\log{n})$, when $d$ is fixed and $n$ goes into infinity. We
+also propose a new encoding scheme based on binary constant weight codes.
+Moreover, an upper bound beating the sphere-packing type bound is given when
+$d$ is relatively close to $n$.",1811.04600v1
+2018-11-13,Classical Access Structures of Ramp Secret Sharing Based on Quantum Stabilizer Codes,"In this paper we consider to use the quantum stabilizer codes as secret
+sharing schemes for classical secrets. We give necessary and sufficient
+conditions for qualified and forbidden sets in terms of quantum stabilizers.
+Then we give a Gilbert-Varshamove-type sufficient condition for existence of
+secret sharing schemes with given parameters, and by using that sufficient
+condition, we show that roughly 19% of participants can be made forbidden
+independently of the size of classical secret, in particular when an $n$-bit
+classical secret is shared among $n$ participants having 1-qubit share each. We
+also consider how much information is obtained by an intermediate set and
+express that amount of information in terms of quantum stabilizers. All the
+results are stated in terms of linear spaces over finite fields associated with
+the quantum stabilizers.",1811.05217v7
+2018-11-13,Enhanced domain wall velocity near a ferromagnetic instability,"Assuming a Fermi liquid behavior for $s$-conduction electrons, we rewrite the
+extended Landau-Lifshitz-Gilbert (LLG) equation renormalized by interactions
+through the Landau parameters $F^{a}_{l}$ ($l=0,1,2 \cdots$) in an explicit
+form to describe the dynamic of a domain wall (DW) due to spin transfer torque
+phenomenon. The interaction between spins of the \textit{s}-conduction
+electrons explains qualitatively the DW velocity experimental observations in
+$\mathrm{Ni_{81}}\mathrm{Fe_{19}}$ (Permalloy) recalculated by us without
+defects or impurity hypothesis. Close to Stoner ferromagnetic instability point
+where $F^{a}_{0} \approx -0.99$, the DW velocity becomes high
+($v^{*}_{DW}\approx 600$ $ms^{-1}$) and critical spin current density becomes
+reduced ($j^{*}_{c}\approx1\times10^{12}$ $Am^{-2}$) when compared to that
+calculated by nonadiabatic approach. At the critical point, the DW velocity
+diverges while critical spin current density at the same point goes to zero.
+Our theory also provides a prediction to looking for materials in which is
+possible applies a smallest critical spin current density and observes higher
+DW velocity.",1811.05380v4
+2018-12-07,Coding over Sets for DNA Storage,"In this paper we study error-correcting codes for the storage of data in
+synthetic deoxyribonucleic acid (DNA). We investigate a storage model where a
+data set is represented by an unordered set of $M$ sequences, each of length
+$L$. Errors within that model are a loss of whole sequences and point errors
+inside the sequences, such as insertions, deletions and substitutions. We
+derive Gilbert-Varshamov lower bounds and sphere packing upper bounds on
+achievable cardinalities of error-correcting codes within this storage model.
+We further propose explicit code constructions than can correct errors in such
+a storage system that can be encoded and decoded efficiently. Comparing the
+sizes of these codes to the upper bounds, we show that many of the
+constructions are close to optimal.",1812.02936v3
+2018-12-14,Computational micromagnetics with Commics,"We present our open-source Python module Commics for the study of the
+magnetization dynamics in ferromagnetic materials via micromagnetic
+simulations. It implements state-of-the-art unconditionally convergent finite
+element methods for the numerical integration of the Landau-Lifshitz-Gilbert
+equation. The implementation is based on the multiphysics finite element
+software Netgen/NGSolve. The simulation scripts are written in Python, which
+leads to very readable code and direct access to extensive post-processing.
+Together with documentation and example scripts, the code is freely available
+on GitLab.",1812.05931v1
+2019-02-01,A Penrose-Type Inequality with Angular Momentum and Charge for Axisymmetric Initial Data,"A lower bound for the ADM mass is established in terms of angular momentum,
+charge, and horizon area in the context of maximal, axisymmetric initial data
+for the Einstein-Maxwell equations which satisfy the weak energy condition. If,
+on the horizon, the given data agree to a certain extent with the associated
+model Kerr-Newman data, then the inequality reduces to the conjectured Penrose
+inequality with angular momentum and charge. In addition, a rigidity statement
+is also proven whereby equality is achieved if and only if the data set arises
+from the canonical slice of a Kerr-Newman spacetime.",1902.00501v3
+2019-02-08,Field-tuned spin excitation spectrum of $kπ$-skyrmion,"We study spin-wave excitation modes of $k\pi$ skyrmion in a magnetic nanodot
+under an external magnetic field along $z$-direction using micromagnetic
+simulations based on Landau-Lifshitz-Gilbert equation. We find that a
+transition of $k\pi$ skyrmion to other skyrmion-like structures appears under
+some critical external field, the corresponding spin-wave spectra are simulated
+for each state in the process of applying magnetic field. For skyrmion, the
+frequencies of excitation modes increases and then decreases with the low
+frequency modes splitting at a critical magnetic field. In addition to the well
+known two in-plane rotational modes and a out-of-plane breathing mode of
+skyrmion, a higher number of excitation modes are found with increasing $k$
+($k=2, 3$). The excitation modes vary as a function of magnetic field, and the
+excitation frequencies for different modes exhibit a rapid or slight change
+depending on the field induced change of magnetization profile. Our study
+indicates the rich spin-wave excitations for $k\pi$ skyrmion and opens a
+possibility in theoretical or experimental investigation of magnonics
+application.",1902.02901v2
+2019-02-08,Simulation of the Magnetization Dynamics of a Single Domain BiFeO$_3$ Thin Film,"The switching dynamics of a single-domain BiFeO$_3$ thin films is
+investigated through combining the dynamics of polarization and Neel vector.
+The evolution of the ferroelectric polarization is described by the
+Landau-Khalatnikov (LK) equation, and the Landau-Lifshitz-Gilbert (LLG)
+equations for spins in two sublattices to model the time evolution of the
+antiferromagnetic order (Neel vector) in a G-type antiferromagnet. This work
+theoretically demonstrates that due to the rotation of the magnetic hard axis
+following the polarization reversal, the Neel vector can be switched by 180
+degrees, while the weak magnetization can remain unchanged. The simulation
+results are consistent with the ab initio calculation, where the Neel vector
+rotates during polarization rotation, and also match our calculation of the
+dynamics of order parameter using Landau-Ginzburg theory. We also find that the
+switching time of the Neel vector is determined by the speed polarization
+switching and is predicted to be as short as 30 ps.",1902.03330v1
+2019-02-13,Dynamics of ferromagnetic domain walls under extreme fields,"We report the existence of a new regime for domain wall motion in uniaxial
+and near-uniaxial ferromagnetic nanowires, characterised by applied magnetic
+fields sufficiently strong that one of the domains becomes unstable. There
+appears a new stable solution of the Landau-Lifshitz-Gilbert equation,
+describing a nonplanar domain wall moving with constant velocity and precessing
+with constant frequency. Even in the presence of thermal noise, the new
+solution can propagate for distances on the order of 500 times the field-free
+domain wall width before fluctuations in the unstable domain become
+appreciable.",1902.04968v3
+2019-02-28,Topological $d$-wave Superconductivity and Nodal Line-Arc Intersections in Weyl Semimetals,"Superconducting Weyl semimetals present a novel and promising system to
+harbor new forms of unconventional topological superconductivity. Within the
+context of time-reversal symmetric Weyl semimetals with $d$-wave
+superconductivity, we demonstrate that the number of Majorana cones equates to
+the number of intersections between the $d$-wave nodal lines and the Fermi
+arcs. We illustrate the importance of nodal line-arc intersections by
+demonstrating the existence of locally stable surface Majorana cones that the
+winding number does not predict. The discrepancy between Majorana cones and the
+winding number necessitates an augmentation of the winding number formulation
+to account for each intersection. In addition, we show that imposing additional
+mirror symmetries globally protect the nodal line-arc intersections and the
+corresponding Majorana cones.",1903.00024v2
+2019-03-07,Stronger L2/L2 Compressed Sensing; Without Iterating,"We consider the extensively studied problem of $\ell_2/\ell_2$ compressed
+sensing. The main contribution of our work is an improvement over [Gilbert, Li,
+Porat and Strauss, STOC 2010] with faster decoding time and significantly
+smaller column sparsity, answering two open questions of the aforementioned
+work.
+  Previous work on sublinear-time compressed sensing employed an iterative
+procedure, recovering the heavy coordinates in phases. We completely depart
+from that framework, and give the first sublinear-time $\ell_2/\ell_2$ scheme
+which achieves the optimal number of measurements without iterating; this new
+approach is the key step to our progress. Towards that, we satisfy the
+$\ell_2/\ell_2$ guarantee by exploiting the heaviness of coordinates in a way
+that was not exploited in previous work. Via our techniques we obtain improved
+results for various sparse recovery tasks, and indicate possible further
+applications to problems in the field, to which the aforementioned iterative
+procedure creates significant obstructions.",1903.02742v1
+2019-03-17,A Brief history of mangnetism,"In this article an overview of the historical development of the key ideas in
+the field of magnetism is presented. The presentation is semi-technical in
+nature.Starting by noting down important contribution of Greeks, William
+Gilbert, Coulomb, Poisson, Oersted, Ampere, Faraday, Maxwell, and Pierre Curie,
+we review early 20th century investigations by Paul Langevin and Pierre Weiss.
+The Langevin theory of paramagnetism and the Weiss theory of ferromagnetism
+were partly successful and real understanding of magnetism came with the advent
+of quantum mechanics. Van Vleck was the pioneer in applying quantum mechanics
+to the problem of magnetism and we discuss his main contributions: (1) his
+detailed quantum statistical mechanical study of magnetism of real gases; (2)
+his pointing out the importance of the crystal fields or ligand fields in the
+magnetic behavior of iron group salts (the ligand field theory); and (3) his
+many contributions to the elucidation of exchange interactions in d electron
+metals. Next, the pioneering contributions (but lesser known) of Dorfman are
+discussed. Then, in chronological order, the key contributions of Pauli,
+Heisenberg, and Landau are presented. Finally, we discuss a modern topic of
+quantum spin liquids.",1903.07031v1
+2019-03-19,Separability Properties of Nilpotent $\mathbb{Q}[x]$-Powered Groups,"In this paper we study conjugacy and subgroup separability properties in the
+class of nilpotent $\mathbb{Q}[x]$-powered groups. Many of the techniques used
+to study these properties in the context of ordinary nilpotent groups carry
+over naturally to this more general class. Among other results, we offer a
+generalization of a theorem due to G. Baumslag. The generalized version states
+that if $G$ is a finitely $\mathbb{Q}[x]$-generated
+$\mathbb{Q}[x]$-torsion-free nilpotent $\mathbb{Q}[x]$-powered group and $H$ is
+a $\mathbb{Q}[x]$-isolated subgroup of $G,$ then for any prime $\pi \in
+\mathbb{Q}[x]$, $\bigcap_{i = 1}^{\infty} G^{{\pi}^{i}}H = H.$",1903.08220v1
+2019-03-24,"Synchronized, periodic, and chaotic dynamics in spin torque oscillator with two free layers","A phase diagram of the magnetization dynamics is studied by numerically
+solving the Landau-Lifshitz-Gilbert (LLG) equation in a spin torque oscillator
+consisting of asymmetric two free layers that are magnetized in in-plane
+direction. We calculated the dynamics for a wide range of current density for
+both low and high field cases, and found many dynamical phases such as
+synchronization, auto-oscillation with different frequencies, and chaotic
+dynamics. The observation of the synchronization indicates the presence of a
+dynamical phase which has not been found experimentally by using the
+conventional electrical detection method. The auto-oscillations with different
+frequencies lead to an oscillation of magnetoresistance with a high frequency,
+which can be measured experimentally. The chaotic and/or periodic behavior of
+magnetoresistance in a high current region, on the other hand, leads to a
+discontinuous change of the peak frequency in Fourier spectrum.",1903.09938v2
+2019-04-07,Hybrid Approaches to Detect Comments Violating Macro Norms on Reddit,"In this dataset paper, we present a three-stage process to collect Reddit
+comments that are removed comments by moderators of several subreddits, for
+violating subreddit rules and guidelines. Other than the fact that these
+comments were flagged by moderators for violating community norms, we do not
+have any other information regarding the nature of the violations. Through this
+procedure, we collect over 2M comments removed by moderators of 100 different
+Reddit communities, and publicly release the data. Working with this dataset of
+removed comments, we identify 8 macro norms---norms that are widely enforced on
+most parts of Reddit. We extract these macro norms by employing a hybrid
+approach---classification, topic modeling, and open-coding---on comments
+identified to be norm violations within at least 85 out of the 100 study
+subreddits. Finally, we label over 40K Reddit comments removed by moderators
+according to the specific type of macro norm being violated, and make this
+dataset publicly available. By breaking down a collection of removed comments
+into more granular types of macro norm violation, our dataset can be used to
+train more nuanced machine learning classifiers for online moderation.",1904.03596v2
+2019-04-11,Triangular array of iron-oxide nanoparticles: A simulation study of intra- and inter-particle magnetism,"A study of spherical maghemite nanoparticles on a two dimensional triangular
+array was carried out using a stochastic Landau-Lifshitz-Gilbert (sLLG)
+approach. The simulation method was first validated with a triangular array of
+simple dipoles, where results show the expected phase transition to a
+ferromagnetic state at a finite temperature. The ground state exhibited a
+continuous degeneracy that was lifted by an order-from-disorder mechanism at
+infinitesimal temperatures with the appearance of a six-fold planar anisotropy.
+The nanoparticle array consisted of 7.5 nm diameter maghemite spheres with
+bulk-like superexchange interactions between Fe-ions in the core, and weaker
+exchange between surface Fe-ions and a radial anisotropy. The triangular
+nanoparticle array ordered at the same reduced temperature as the simple dipole
+array, but exhibited different behaviour at low temperatures due to the surface
+anisotropy. We find that the vacancies on the octahedral sites in the
+nanoparticles combine with the surface anisotropy to produce an effective
+random temperature-dependent anisotropy for each particle. This leads to a
+reduction in the net magnetization of the nanoparticle array at zero
+temperature compared to the simple dipole array.",1904.05515v1
+2019-04-15,Mathematical analysis of weak and strong solutions to an evolutionary model for magnetoviscoelasticity,"The paper is concerned with the analysis of an evolutionary model for
+magnetoviscoelastic materials in two dimensions. The model consists of a
+Navier-Stokes system featuring a dependence of the stress tensor on elastic and
+magnetic terms, a regularized system for the evolution of the deformation
+gradient and the Landau-Lifshitz-Gilbert system for the dynamics of the
+magnetization.
+  First, we show that our model possesses global in time weak solutions, thus
+extending work by Bene\v{s}ov\'a et al. 2018. Compared to that work, we include
+the stray field energy and relax the assumptions on the elastic energy density.
+Second, we prove the local in time existence of strong solutions. Both
+existence results are based on the Galerkin method. Finally, we show a
+weak-strong uniqueness property.",1904.07179v1
+2019-04-25,Message Randomization and Strong Security in Quantum Stabilizer-Based Secret Sharing for Classical Secrets,"We improve the flexibility in designing access structures of quantum
+stabilizer-based secret sharing schemes for classical secrets, by introducing
+message randomization in their encoding procedures. We generalize the
+Gilbert-Varshamov bound for deterministic encoding to randomized encoding of
+classical secrets. We also provide an explicit example of a ramp secret sharing
+scheme with which multiple symbols in its classical secret are revealed to an
+intermediate set, and justify the necessity of incorporating strong security
+criterion of conventional secret sharing. Finally, we propose an explicit
+construction of strongly secure ramp secret sharing scheme by quantum
+stabilizers, which can support twice as large classical secrets as the
+McEliece-Sarwate strongly secure ramp secret sharing scheme of the same share
+size and the access structure.",1904.11114v3
+2019-05-02,Benchmark Instances and Branch-and-Cut Algorithm for the Hashiwokakero Puzzle,"Hashiwokakero, or simply Hashi, is a Japanese single-player puzzle played on
+a rectangular grid with no standard size. Some cells of the grid contain a
+circle, called island, with a number inside it ranging from one to eight. The
+remaining positions of the grid are empty. The player must connect all of the
+islands by drawing a series of horizontal or vertical bridges between them,
+respecting a series of rules: the number of bridges incident to an island
+equals the number indicated in the circle, at most two bridges are incident to
+any side of an island, bridges cannot cross each other or pass through islands,
+and each island must eventually be reachable from any other island. In this
+paper, we present some complexity results and relationships between Hashi and
+well-known graph theory problems. We give a formulation of the problem by means
+of an integer linear mathematical programming model, and apply a branch-and-cut
+algorithm to solve the model in which connectivity constraints are dynamically
+generated. We also develop a puzzle generator. Our experiments on 1440 Hashi
+puzzles show that the algorithm can consistently solve hard puzzles with up to
+400 islands.",1905.00973v1
+2019-05-06,An excess of non-Gaussian fluctuations in the cosmic infrared background consistent with gravitational lensing,"The cosmic infrared background (CIB) is gravitationally lensed. A
+quadratic-estimator technique that is inherited from lensing analyses of the
+cosmic microwave background (CMB) can be applied to detect the CIB lensing
+effects. However, the CIB fluctuations are intrinsically strongly non-Gaussian,
+making CIB lensing reconstruction highly biased. We perform numerical
+simulations to estimate the intrinsic non-Gaussianity and establish a
+cross-correlation approach to precisely extract the CIB lensing signal from raw
+data. We apply this technique to CIB data from the Planck satellite and
+cross-correlate the resulting lensing estimate with the CIB data, galaxy number
+counts and the CMB lensing potential. We detect an excess that is consistent
+with a lensing contribution at $>4\sigma$.",1905.02084v1
+2019-05-14,Multi-reference quantum chemistry protocol for simulating autoionization spectra: Test of ionization continuum models for the neon atom,"In this contribution we present a protocol to evaluate partial and total
+Auger decay rates combining the restricted active space self-consistent field
+electronic structure method for the bound part of the spectrum and numerically
+obtained continuum orbitals in the single-channel scattering theory framework.
+On top of that, the two-step picture is employed to evaluate the partial rates.
+The performance of the method is exemplified for the prototypical Auger decay
+of the neon $1s^{-1}3p$ resonance. Different approximations to obtain the
+continuum orbitals, the partial rate matrix elements, and the electronic
+structure of the bound part are tested against theoretical and experimental
+reference data. It is demonstrated that the partial and total rates are most
+sensitive to the accuracy of the continuum orbitals. For instance, it is
+necessary to account for the direct Coulomb potential of the ion for the
+determination of the continuum wave functions. The Auger energies can be
+reproduced quite well already with a rather small active space. Finally,
+perspectives of the application of the proposed protocol to molecular systems
+are discussed.",1905.05785v2
+2019-06-16,A concise guide to existing and emerging vehicle routing problem variants,"Vehicle routing problems have been the focus of extensive research over the
+past sixty years, driven by their economic importance and their theoretical
+interest. The diversity of applications has motivated the study of a myriad of
+problem variants with different attributes. In this article, we provide a
+concise overview of existing and emerging problem variants. Models are
+typically refined along three lines: considering more relevant objectives and
+performance metrics, integrating vehicle routing evaluations with other
+tactical decisions, and capturing fine-grained yet essential aspects of modern
+supply chains. We organize the main problem attributes within this structured
+framework. We discuss recent research directions and pinpoint current
+shortcomings, recent successes, and emerging challenges.",1906.06750v2
+2019-07-01,Formation process of skyrmion lattice domain boundaries: The role of grain boundaries,"We report on the formation process of skyrmion lattice (SkL) domain
+boundaries in FeGe using Lorentz transmission electron microscopy and
+small-angle electron diffraction. We observed that grain boundaries and edges
+play an important role in the formation of SkL domain boundaries; The SkL
+domain boundary is stabilized at the intersection of two grains. A
+micromagnetic simulation using the Landau-Lifshitz-Gilbert equation revealed
+that the SkL domains separated by a boundary represent the lowest energy
+configuration. Conversely, in a wide area, SkL domain boundaries were not
+formed and SkL domains with different orientations rotated to form a single SkL
+domain.",1907.00774v1
+2019-07-02,Quantum Data-Syndrome Codes,"Performing active quantum error correction to protect fragile quantum states
+highly depends on the correctness of error information--error syndromes. To
+obtain reliable error syndromes using imperfect physical circuits, we propose
+the idea of quantum data-syndrome (DS) codes that are capable of correcting
+both data qubits and syndrome bits errors. We study fundamental properties of
+quantum DS codes, including split weight enumerators, generalized MacWilliams
+identities, and linear programming bounds. In particular, we derive Singleton
+and Hamming-type upper bounds on degenerate quantum DS codes. Then we study
+random DS codes and show that random DS codes with a relatively small
+additional syndrome measurements achieve the Gilbert-Varshamov bound of
+stabilizer codes. Constructions of quantum DS codes are also discussed. A
+family of quantum DS codes is based on classical linear block codes, called
+syndrome measurement codes, so that syndrome bits are encoded in additional
+redundant stabilizer measurements. Another family of quantum DS codes is
+CSS-type quantum DS codes based on classical cyclic codes, and this includes
+the Steane code and the quantum Golay code.",1907.01393v1
+2019-07-02,Prediction of topological Hall effect in a driven magnetic domain wall,"We investigate the possible emergence of topological Hall effect (THE) in a
+driven magnetic DW. Numerical simulation based on the
+Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation shows that the emergent
+magnetic flux appears when the DW is in a non-equilibrium state. The magnitude
+of magnetic flux is modulated by Dzyaloshinskii-Moriya interaction (DMI) or
+in-plane longitudinal magnetic field, providing an experimental test of the
+predicted THE. These results indicate that the THE can be observed even in a
+topologically trivial magnetic DW, and therefore open up new possibility to
+electrically detect the dynamical spin structure.",1907.01648v2
+2019-07-04,Resonant Acoustic Wave Assisted Spin-Transfer-Torque Switching of Nanomagnets,"We report the possibility of achieving an order of magnitude reduction in the
+energy dissipation needed to write bits in perpendicular magnetic tunnel
+junctions (p-MTJs) by simulating the magnetization dynamics under a combination
+of resonant surface acoustic waves (r-SAW) and spin-transfer-torque (STT). The
+magnetization dynamics were simulated using the Landau-Lifshitz-Gilbert
+equation under macrospin assumption with the inclusion of thermal noise. The
+resonant magnetization dynamics in the magnetostrictive nanomagnet build over
+few 10s of cycles of SAW application that drives the magnetization to precess
+in a cone with a deflection of ~45 degrees from the perpendicular direction.
+This reduces the STT current density required to switch the magnetization
+direction without increasing the STT application time or degrading the
+switching probability in the presence of room temperature thermal noise. This
+could lead to a pathway to achieve energy efficient switching of spin transfer
+torque random access memory (STTRAM) whose lateral dimensions can be scaled
+aggressively despite using materials with low magnetostriction by employing
+resonant excitation.",1907.02255v1
+2019-07-04,Second-order semi-implicit projection methods for micromagnetics simulations,"Micromagnetics simulations require accurate approximation of the
+magnetization dynamics described by the Landau-Lifshitz-Gilbert equation, which
+is nonlinear, nonlocal, and has a non-convex constraint, posing interesting
+challenges in developing numerical methods. In this paper, we propose two
+second-order semi-implicit projection methods based on the second-order
+backward differentiation formula and the second-order interpolation formula
+using the information at previous two temporal steps. Unconditional unique
+solvability of both methods is proved, with their second-order accuracy
+verified through numerical examples in both 1D and 3D. The efficiency of both
+methods is compared to that of another two popular methods. In addition, we
+test the robustness of both methods for the first benchmark problem with a
+ferromagnetic thin film material from National Institute of Standards and
+Technology.",1907.02358v1
+2019-07-11,"Astro2020 Activity, Project of State of the Profession Consideration (APC) White Paper: All-Sky Near Infrared Space Astrometry. State of the Profession Considerations: Development of Scanning NIR Detectors for Astronomy","Gaia is a revolutionary space mission developed by ESA and is delivering 5
+parameter astrometry, photometry and radial velocities over the whole sky with
+astrometric accuracies down to a few tens of micro-arcseconds. A weakness of
+Gaia is that it only operates at optical wavelengths. However, much of the
+Galactic centre and the spiral arm regions, important for certain studies, are
+obscured by interstellar extinction and this makes it difficult for Gaia to
+deeply probe. This problem can be overcome by switching to the Near Infra-Red
+(NIR) but this is not possible with silicon CCDs. Additionally, to scan the
+entire sky and make global absolute parallax measurements the spacecraft must
+have a constant rotation and this requires the detectors operate in Time
+Delayed Integration (TDI) mode or similar.",1907.05191v1
+2019-07-21,Performance of a low-parasitic frequency-domain multiplexing readout,"Frequency-domain multiplexing is a readout technique for transition edge
+sensor bolometer arrays used on modern CMB experiments, including the SPT-3G
+receiver. Here, we present design details and performance measurements for a
+low-parasitic frequency-domain multiplexing readout. Reducing the parasitic
+impedance of the connections between cryogenic components provides a path to
+improving both the crosstalk and noise performance of the readout. Reduced
+crosstalk will in turn allow higher multiplexing factors. We have demonstrated
+a factor of two improvement in parasitic resistance compared to SPT-3G
+hardware. Reduced parasitics also permits operation of lower-resistance
+bolometers, which enables better optimization of R$_{\rm{bolo}}$ for improved
+readout noise performance. The prototype system exhibits noise performance
+comparable to SPT-3G readout hardware when operating SPT-3G detectors.",1907.09035v1
+2019-08-09,MakeSense: An IoT Testbed for Social Research of Indoor Activities,"There has been increasing interest in deploying IoT devices to study human
+behaviour in locations such as homes and offices. Such devices can be deployed
+in a laboratory or `in the wild' in natural environments. The latter allows one
+to collect behavioural data that is not contaminated by the artificiality of a
+laboratory experiment. Using IoT devices in ordinary environments also brings
+the benefits of reduced cost, as compared with lab experiments, and less
+disturbance to the participants' daily routines which in turn helps with
+recruiting them into the research. However, in this case, it is essential to
+have an IoT infrastructure that can be easily and swiftly installed and from
+which real-time data can be securely and straightforwardly collected. In this
+paper, we present MakeSense, an IoT testbed that enables real-world
+experimentation for large scale social research on indoor activities through
+real-time monitoring and/or situation-aware applications. The testbed features
+quick setup, flexibility in deployment, the integration of a range of IoT
+devices, resilience, and scalability. We also present two case studies to
+demonstrate the use of the testbed, one in homes and one in offices.",1908.03380v1
+2019-08-13,On Steane-Enlargement of Quantum Codes from Cartesian Product Point Sets,"In this work, we study quantum error-correcting codes obtained by using
+Steane-enlargement. We apply this technique to certain codes defined from
+Cartesian products previously considered by Galindo et al. in [4]. We give
+bounds on the dimension increase obtained via enlargement, and additionally
+give an algorithm to compute the true increase. A number of examples of codes
+are provided, and their parameters are compared to relevant codes in the
+literature, which shows that the parameters of the enlarged codes are
+advantageous. Furthermore, comparison with the Gilbert-Varshamov bound for
+stabilizer quantum codes shows that several of the enlarged codes match or
+exceed the parameters promised by the bound.",1908.04560v1
+2019-08-17,Band-pass Magnetic Tunnel Junction based Magnetoresistive Random Access Memory,"We propose spin transfer torque--magnetoresistive random access memory
+(STT-MRAM) based on magneto-resistance and spin transfer torque physics of
+band-pass spin filtering. Utilizing the electronic analogs of optical phenomena
+such as anti-reflection coating and resonance for spintronic devices, we
+present the design of an STT-MRAM device with improved features when compared
+with a traditional trilayer device. The device consists of a superlattice
+heterostructure terminated with the anti-reflective regions sandwiched between
+the fixed and free ferromagnetic layers. Employing the Green's function spin
+transport formalism coupled self-consistently with the stochastic
+Landau-Lifshitz-Gilbert-Slonczewski equation, we present the design of an
+STT-MRAM based on the band-pass filtering having an ultra-high TMR (3.5*10e4)
+and large spin current. We demonstrate that the STT-MRAM design having
+band-pass spin filtering are nearly 1100% more energy efficient than
+traditional trilayer magnetic tunnel junction (MTJ) based STT-MRAM. We also
+present detailed probabilistic switching and energy analysis for a trilayer MTJ
+and band-pass filtering based STT-MRAM. Our predictions serve as a template to
+consider the heterostructures for next-generation spintronic device
+applications.",1908.06279v1
+2019-09-09,Narrow autoresonant magnetization structures in finite length ferromagnetic nanoparticles,"The autoresonant approach to excitation and control of large amplitude
+uniformly precessing magnetization structures in finite length easy axis
+ferromagnetic nanoparticles is suggested and analyzed within the
+Landau-Lifshitz-Gilbert model. These structures are excited by using a
+spatially uniform, oscillating, chirped frequency magnetic field, while the
+localization is imposed via boundary conditions. The excitation requires the
+amplitude of the driving oscillations to exceed a threshold. The dissipation
+effect on the threshold is also discussed. The autoresonant driving effectively
+compensates the effect of dissipation, but lowers the maximum amplitude of the
+excited structures. Fully nonlinear localized autoresonant solutions are
+illustrated in simulations and described via an analog of a quasi-particle in
+an effective potential. The precession frequency of these solutions is
+continuously locked to that of the drive, while the spatial magnetization
+profile approaches the soliton limit when the length of the nanoparticle and
+the amplitude of the excited solution increase.",1909.03671v1
+2019-09-09,Reliability and Error Burst Length Analysis of Wireless Multi-Connectivity,"Multi-connectivity offers diversity in terms of multiple interfaces through
+which the data can be sent, thereby improving simultaneously the overall
+reliability and latency. This makes interface diversity a natural candidate for
+supporting Ultra-Reliable Low Latency Communications (URLLC). This work
+investigates how the packet error statistics from different interfaces impacts
+the overall reliability-latency characteristics. We use the simple
+Gilbert-Elliott model for burst errors and estimate its parameters based on
+experimental measurement traces from LTE and {Wi-Fi} packet transmissions
+collected over several days. The results show that using interface diversity
+configurations that include at least one {Wi-Fi} interface leads to, somewhat
+surprisingly, since Wi-Fi is generally less reliable than LTE, superior results
+in terms of packet success and error burst duration. Another interesting
+finding is that {Wi-Fi}-based interface diversity configurations outperform
+even ultra-reliable single links.",1909.03875v1
+2019-09-13,Hidden spin-orbital order in the Kitaev hyperhoneycomb $β$-Li$_2$IrO$_3$,"We report the existence of a phase transition at high temperature in the 3D
+Kitaev candidate material, $\beta$-Li$_2$IrO$_3$. We show that the transition
+is bulk, intrinsic and orders a tiny magnetic moment with a spatially
+anisotropic saturation moment. We show that even though this transition is
+global, it does not freeze the local Ir moments, which order at much lower
+temperatures into an incommensurate state. Rather, the ordered moment has an
+orbital origin that is coupled to spin correlations, likely of a Kitaev origin.
+The separate ordering of spin-correlated orbital moments and of local Ir
+moments reveals a novel way in which magnetic frustration in Kitaev systems can
+lead to coexisting magnetic states.",1909.06355v1
+2019-10-08,Gravitational Lensing of the Cosmic Neutrino Background,"We study gravitational lensing of the cosmic neutrino background. This signal
+is undetectable for the foreseeable future, but there is a rich trove of
+information available. At least some of the neutrinos from the early universe
+will be non-relativistic today, with a closer surface of last scattering
+(compared to the cosmic microwave background) and with larger angles of
+deflection. Lensing of massive neutrinos is strongly chromatic: both the
+amplitude of lensing and the cosmic time at which the potential is traversed
+depend on neutrino momentum, in principle giving access to our entire causal
+volume, not restricted to the light cone. As a concrete example, we focus on
+the case where the cosmic neutrino background would be strongly lensed when
+passing through halos of galaxy clusters and galaxies. We calculate the
+Einstein radius for cosmic neutrinos and investigate the impact of neutrino
+mass.",1910.03550v3
+2019-10-17,A multi-scale approach for magnetisation dynamics: Unraveling exotic magnetic states of matter,"Crystallographic lattice defects strongly influence dynamical properties of
+magnetic materials at both microscopic and macroscopic length scales. A
+multi-scale approach to magnetisation dynamics, which is presented in this
+paper, accurately captures such effects. The method is illustrated using
+examples of systems with localized, non-trivial topological properties, e.g. in
+the form of skyrmions and chiral domain walls that interact with lattice
+dislocations. Technical aspects of the methodology involve multi-scale
+magnetisation dynamics that connects atomistic and continuum descriptions. The
+technique is capable of solving the Landau-Lifshitz-Gilbert equations
+efficiently in two regions of a magnetic material --- the mesoscopic and the
+atomistic regions, which are coupled in a seamless way. It is demonstrated that
+this methodology allows simulating realistically-sized magnetic skyrmions
+interacting with material defects and novel physical effects, uncovered using
+this theoretical methodology, are described.",1910.07807v1
+2019-10-21,Generation of exchange magnons in thin ferromagnetic films by ultrashort acoustic pulses,"We investigate generation of exchange magnons by ultrashort, picosecond
+acoustic pulses propagating through ferromagnetic thin films. Using the
+Landau-Lifshitz-Gilbert equations we derive the dispersion relation for
+exchange magnons for an external magnetic field tilted with respect to the film
+normal. Decomposing the solution in a series of standing spin wave modes, we
+derive a system of ordinary differential equations and driven harmonic
+oscillator equations describing the dynamics of individual magnon mode. The
+external magnetoelastic driving force is given by the time-dependent spatial
+Fourier components of acoustic strain pulses inside the layer. Dependencies of
+the magnon excitation efficiencies on the duration of the acoustic pulses and
+the external magnetic field highlight the role of acoustic bandwidth and
+phonon-magnon phase matching. Our simulations for ferromagnetic nickel evidence
+the possibility of ultrafast magneto-acoustic excitation of exchange magnons
+within the bandwidth of acoustic pulses in thin samples under conditions
+readily obtained in femtosecond pump-probe experiments.",1910.09481v1
+2019-11-08,A filamentary cascade model of the inertial range,"This paper develops a simple model of the inertial range of turbulent flow,
+based on a cascade of vortical filaments. A binary branching structure is
+proposed, involving the splitting of filaments at each step into pairs of
+daughter filaments with differing properties, in effect two distinct
+simultaneous cascades. Neither of these cascades has the Richardson-Kolmogorov
+exponent of 1/3. This bimodal structure is also different from bifractal models
+as vorticity volume is conserved. If cascades are assumed to be initiated
+continuously and throughout space we obtain a model of the inertial range of
+stationary turbulence. We impose the constraint associated with Kolmogorov's
+four-fifths law and then adjust the splitting to achieve good agreement with
+the observed structure exponents $\zeta_p$. The presence of two elements to the
+cascade is responsible for the nonlinear dependence of $\zeta_p$ upon $p$.
+  A single cascade provides a model for the initial-value problem of the
+Navier--Stokes equations in the limit of vanishing viscosity. To simulate this
+limit we let the cascade continue indefinitely, energy removal occurring in the
+limit. We are thus able to compute the decay of energy in the model.",1911.03537v2
+2019-11-14,Beyond Pairwise Comparisons in Social Choice: A Setwise Kemeny Aggregation Problem,"In this paper, we advocate the use of setwise contests for aggregating a set
+of input rankings into an output ranking. We propose a generalization of the
+Kemeny rule where one minimizes the number of k-wise disagreements instead of
+pairwise disagreements (one counts 1 disagreement each time the top choice in a
+subset of alternatives of cardinality at most k differs between an input
+ranking and the output ranking). After an algorithmic study of this k-wise
+Kemeny aggregation problem, we introduce a k-wise counterpart of the majority
+graph. This graph reveals useful to divide the aggregation problem into several
+sub-problems, which enables to speed up the exact computation of a consensus
+ranking. By introducing a k-wise counterpart of the Spearman distance, we also
+provide a 2-approximation algorithm for the k-wise Kemeny aggregation problem.
+We conclude with numerical tests.",1911.06226v2
+2019-11-15,A geometric look at momentum flux and stress in fluid mechanics,"We develop a geometric formulation of fluid dynamics, valid on arbitrary
+Riemannian manifolds, that regards the momentum-flux and stress tensors as
+1-form valued 2-forms, and their divergence as a covariant exterior derivative.
+We review the necessary tools of differential geometry and obtain the
+corresponding coordinate-free form of the equations of motion for a variety of
+inviscid fluid models -- compressible and incompressible Euler equations,
+Lagrangian-averaged Euler-$\alpha$ equations, magnetohydrodynamics and
+shallow-water models -- using a variational derivation which automatically
+yields a symmetric momentum flux. We also consider dissipative effects and
+discuss the geometric form of the Navier--Stokes equations for viscous fluids
+and of the Oldroyd-B model for visco-elastic fluids.",1911.06613v2
+2019-11-18,Theoretical condition for switching the magnetization in a perpendicularly magnetized ferromagnet via the spin Hall effect,"A theoretical formula is derived for the threshold current to switch a
+perpendicular magnetization in a ferromagnet by the spin Hall effect. The
+numerical simulation of the Landau-Lifshitz-Gilbert equation indicates that
+magnetization switching is achieved when the steady-state solution of the
+magnetization in the presence of the current is outside an energetically
+unstable region. Based on the numerical result, an analytical theory deriving
+the threshold current is developed by focusing on the first-order perturbation
+to the unstable state. The analytical formula clarifies that the magnitude of
+the magnetic field applied to the current direction should be larger than 15\%
+of the perpendicular magnetic anisotropy field, and the current is less than
+the derived threshold value.",1911.07961v1
+2019-12-11,Constructions of quasi-twisted quantum codes,"In this work, our main objective is to construct quantum codes from
+quasi-twisted (QT) codes. At first, a necessary and sufficient condition for
+Hermitian self-orthogonality of QT codes is introduced by virtue of the Chinese
+Remainder Theorem (CRT). Then we utilize these self-orthogonal QT codes to
+provide quantum codes via the famous Hermitian Construction. Moreover, we
+present a new construction method of q-ary quantum codes, which can be viewed
+as an effective generalization of the Hermitian Construction. General QT codes
+that are not self-orthogonal are also employed to construct quantum codes. As
+the computational results, some binary, ternary and quaternary quantum codes
+are constructed and their parameters are determined, which all exceed the
+Quantum Gilbert-Varshamov (GV) Bound. In the binary case, a small number of
+quantum codes are derived with strictly improved parameters compared with the
+current records. In the ternary and quaternary cases, our codes fill some gaps
+or have better performances than the current results.",1912.05142v2
+2019-12-12,The strange metal Hall effect connects quantum criticality and superconductivity in an iron-based superconductor,"Many unconventional superconductors exhibit a common set of anomalous charge
+transport properties that characterize them as `strange metals', which provides
+hope that there is single theory that describes them. However,
+model-independent connections between the strange metal and superconductivity
+have remained elusive. In this letter, we show that the Hall effect of the
+unconventional superconductor BaFe$_2$(As$_{1-x}$P$_x$)$_2$ contains an
+anomalous contribution arising from the correlations within the strange metal.
+This term has a distinctive dependence on magnetic field, which allows us to
+track its behavior across the doping-temperature phase diagram, even under the
+superconducting dome. These measurements demonstrate that the strange metal
+Hall component emanates from a quantum critical point and, in the zero
+temperature limit, decays in proportion to the superconducting critical
+temperature. This creates a clear and novel connection between quantum
+criticality and superconductivity, and suggests that similar connections exist
+in other strange metal superconductors.",1912.06130v1
+2019-12-17,SINR percolation for Cox point processes with random powers,"Signal-to-interference plus noise ratio (SINR) percolation is an
+infinite-range dependent variant of continuum percolation modeling connections
+in a telecommunication network. Unlike in earlier works, in the present paper
+the transmitted signal powers of the devices of the network are assumed random,
+i.i.d. and possibly unbounded. Additionally, we assume that the devices form a
+stationary Cox point process, i.e., a Poisson point process with stationary
+random intensity measure, in two or higher dimensions. We present the following
+main results. First, under suitable moment conditions on the signal powers and
+the intensity measure, there is percolation in the SINR graph given that the
+device density is high and interferences are sufficiently reduced, but not
+vanishing. Second, if the interference cancellation factor $\gamma$ and the
+SINR threshold $\tau$ satisfy $\gamma \geq 1/(2\tau)$, then there is no
+percolation for any intensity parameter. Third, in the case of a Poisson point
+process with constant powers, for any intensity parameter that is supercritical
+for the underlying Gilbert graph, the SINR graph also percolates with some
+small but positive interference cancellation factor.",1912.07895v2
+2019-12-18,Magnetic hysteresis behavior of granular manganite La$_{0.67}$Ca$_{0.33}$MnO$_3$ nanotubes,"A silicon micromechanical torsional oscillator is used to measure the
+hysteresis loops of two manganite La_0.67Ca_0.33MnO_3 nanotubes at different
+temperatures, applying an external field along its main axes. These structures
+are composed of nanograins with a ferromagnetic core surrounded by a dead
+layer. Micromagnetic calculations based on the stochastic
+Landau-Lifshitz-Gilbert equation, are performed to validate a simple model that
+allows for quantitatively describing the ferromagnetic behavior of the system.
+Further simulations are used to analyze the experimental data more in depth and
+to calculate the coercive field, the saturation and remanent magnetizations,
+and the effective magnetic volume for single nanotubes, over a wide temperature
+range.",1912.08844v2
+2019-12-30,Distribution of the minimal distance of random linear codes,"In this paper, we study the distribution of the minimal distance (in the
+Hamming metric) of a random linear code of dimension $k$ in $\mathbb{F}_q^n$.
+We provide quantitative estimates showing that the distribution function of the
+minimal distance is close ({\it{}superpolynomially} in $n$)to the cumulative
+distribution function of the minimum of $(q^k-1)/(q-1)$ independent binomial
+random variables with parameters $\frac{1}{q}$ and $n$. The latter, in turn,
+converges to a Gumbel distribution at integer points when $\frac{k}{n}$
+converges to a fixed number in $(0,1)$. Our result confirms in a strong sense
+that apart from identification of the weights of proportional codewords, the
+probabilistic dependencies introduced by the linear structure of the random
+code, produce a negligible effect on the minimal code weight. As a corollary of
+the main result, we obtain an improvement of the Gilbert--Varshamov bound for
+$2<q<49$.",1912.12833v2
+2020-01-12,Magnetic Skyrmions in FePt Square-Based Nanoparticles Around Room-Temperature,"Magnetic skyrmions formed at temperatures around room temperature in
+square-based parallelepiped magnetic FePt nanoparticles with perpendicular
+magnetocrystalline anisotropy (MCA) were studied during the magnetization
+reversal using micromagnetic simulations. Finite Differences (FD) method were
+used for the solution of the Landau-Lifshitz-Gilbert equation. Magnetic
+configurations exhibiting N\'eel skyrmionic formations were detected. The
+magnetic skyrmions can be created in different systems generated by the
+variation of external field, side length and width of the squared-based
+parallelepiped magnetic nanoparticles. Micromagnetic configurations revealed a
+variety of states which include skyrmionic textures with one distinct skyrmion
+formed and being stable for a range of external fields around room-temperature.
+The size of the formed N\'eel skyrmion is calculated as a function of the
+external field, temperature, MCA and nanoparticle's geometrical characteristic
+lengths which can be adjusted to produce N\'eel type skyrmions on demand having
+diameters down to 12 nm. The micromagnetic simulations revealed that stable
+skyrmions at the temperature range 270 - 330 K can be created for FePt magnetic
+nanoparticle systems lacking of chiral interactions such as
+Dzyaloshinskii-Moriya.",2001.03902v3
+2020-01-20,Investigation of Patient-sharing Networks Using a Bayesian Network Model Selection Approach for Congruence Class Models,"A Bayesian approach to conduct network model selection is presented for a
+general class of network models referred to as the congruence class models
+(CCMs). CCMs form a broad class that includes as special cases several common
+network models, such as the Erd\H{o}s-R\'{e}nyi-Gilbert model, stochastic block
+model and many exponential random graph models. Due to the range of models able
+to be specified as a CCM, investigators are better able to select a model
+consistent with generative mechanisms associated with the observed network
+compared to current approaches. In addition, the approach allows for
+incorporation of prior information. We utilize the proposed Bayesian network
+model selection approach for CCMs to investigate several mechanisms that may be
+responsible for the structure of patient-sharing networks, which are associated
+with the cost and quality of medical care. We found evidence in support of
+heterogeneity in sociality but not selective mixing by provider type nor
+degree.",2001.06974v1
+2020-02-11,Fidimag -- a finite difference atomistic and micromagnetic simulation package,"Fidimag is an open-source scientific code for the study of magnetic materials
+at the nano- or micro-scale using either atomistic or finite difference
+micromagnetic simulations, which are based on solving the
+Landau-Lifshitz-Gilbert equation. In addition, it implements simple procedures
+for calculating energy barriers in the magnetisation through variants of the
+nudged elastic band method. This computer software has been developed with the
+aim of creating a simple code structure that can be readily installed, tested,
+and extended. An agile development approach was adopted, with a strong emphasis
+on automated builds and tests, and reproducibility of results. The main code
+and interface to specify simulations are written in Python, which allows simple
+and readable simulation and analysis configuration scripts. Computationally
+costly calculations are written in C and exposed to the Python interface as
+Cython extensions. Docker containers are shipped for a convenient setup
+experience. The code is freely available on GitHub and includes documentation
+and examples in the form of Jupyter notebooks.",2002.04318v1
+2020-01-13,Malware propagation in urban D2D networks,"We introduce and analyze models for the propagation of malware in pure D2D
+networks given via stationary Cox-Gilbert graphs. Here, the devices form a
+Poisson point process with random intensity measure $\lambda\Lambda$, where
+$\Lambda$ is stationary and given, for example, by the edge-length measure of a
+realization of a Poisson-Voronoi tessellation that represents an urban street
+system. We assume that, at initial time, a typical device at the center of the
+network carries a malware and starts to infect neighboring devices after random
+waiting times. Here we focus on Markovian models, where the waiting times are
+exponential random variables, and non-Markovian models, where the waiting times
+feature strictly positive minimal and finite maximal waiting times. We present
+numerical results for the speed of propagation depending on the system
+parameters. In a second step, we introduce and analyze a counter measure for
+the malware propagation given by special devices called white knights, which
+have the ability, once attacked, to eliminate the malware from infected devices
+and turn them into white knights. Based on simulations, we isolate parameter
+regimes in which the malware survives or is eliminated, both in the Markovian
+and non-Markovian setting.",2002.06248v1
+2020-02-17,How fast can you update your MST? (Dynamic algorithms for cluster computing),"Imagine a large graph that is being processed by a cluster of computers,
+e.g., described by the $k$-machine model or the Massively Parallel Computation
+Model. The graph, however, is not static; instead it is receiving a constant
+stream of updates. How fast can the cluster process the stream of updates? The
+fundamental question we want to ask in this paper is whether we can update the
+graph fast enough to keep up with the stream. We focus specifically on the
+problem of maintaining a minimum spanning tree (MST), and we give an algorithm
+for the $k$-machine model that can process $O(k)$ graph updates per $O(1)$
+rounds with high probability. (And these results carry over to the Massively
+Parallel Computation (MPC) model.) We also show a lower bound, i.e., it is
+impossible to process $k^{1+\epsilon}$ updates in $O(1)$ rounds. Thus we
+provide a nearly tight answer to the question of how fast a cluster can respond
+to a stream of graph modifications while maintaining an MST.",2002.06762v1
+2020-02-22,Bose-Einstein Condensation of Nonequilibrium Magnons in Confined Systems,"We study the formation of a room temperature magnon Bose-Einstein condensate
+(BEC) in nanoscopic systems and demonstrate that its lifetime is influenced by
+the spatial confinement. We predict how dipolar interactions and nonlinear
+magnon scattering assist in the generation of a metastable magnon BEC in
+energy-quantized nanoscopic devices. We verify our prediction by a full
+numerical simulation of the Landau-Lifshitz-Gilbert equation and demonstrate
+the generation of magnon BEC in confined insulating magnets of yttrium iron
+garnet. We directly map out the nonlinear magnon scattering processes behind
+this phase transition to show how fast quantized thermalization channels allow
+the BEC formation in confined structures. Based on our results, we discuss a
+new mechanism to manipulate the BEC lifetime in nanoscaled systems. Our study
+greatly extends the freedom to study the dynamics of magnon BEC in realistic
+systems and to design integrated circuits for BEC-based applications at room
+temperature.",2002.09777v2
+2020-02-25,Bias-field-free spin Hall nano-oscillators with an out-of-plane precession mode,"Spin Hall nano-oscillators (SHNOs) are promising candidates for new microwave
+oscillators with high durability due to a small driving current. However,
+conventional SHNOs with an in-plane precession (IPP) mode require a bias field
+for stable oscillations which is not favored in certain applications such as
+neuromorphic computing. Here, we propose and theoretically analyze a
+bias-field-free SHNO with an in-plane hard axis and an out-of-plane precession
+(OPP) mode by solving the Landau-Lifshitz-Gilbert (LLG) equation analytically
+and numerically. We derive formulas for driving currents and precession
+frequency, and show that they are in good agreement with numerical simulation
+results. We show that our proposed SHNOs can be driven by much smaller bias
+current than conventional spin torque nano-oscillators.",2002.10753v1
+2020-03-06,Spin-accumulation induced magnetic texture in a metal-insulator bilayer,"We consider the influence of a spin accumulation in a normal metal on the
+magnetic statics and dynamics in an adjacent magnetic insulator. In particular,
+we focus on arbitary angles between the spin accumulation and the easy-axis of
+the magnetic insulator. Based on Landau-Lifshitz-Gilbert phenomenology
+supplemented with magnetoelectronic circuit theory, we find that the magnetic
+texture twists into a stable configuration that turns out to be described by a
+virtual, or image, domain wall configuration, i.e., a domain wall outside the
+ferromagnet. We show that even when the spin accumulation is perpendicular to
+the anisotropy axis, the magnetic texture develops a component parallel to the
+spin accumulation for sufficiently large spin bias. The emergence of this
+parallel component gives rise to threshold behavior in the spin Hall
+magnetoresistance and nonlocal magnon transport. This threshold can be used to
+design novel spintronic and magnonic devices that can be operated without
+external magnetic fields.",2003.03226v1
+2020-04-05,Domain wall diode based on functionally graded Dzyaloshinskii-Moriya interaction,"We present a general approach for studying the dynamics of domain walls in
+biaxial ferromagnetic stripes with functionally graded Dzyaloshinskii-Moriya
+interaction (DMI). By engineering the spatial profile of the DMI parameter we
+propose the concept of a diode, which implements filtering of domain walls of
+certain topological charge and helicity. We base our study on phenomenological
+Landau-Lifshitz-Gilbert equations with additional Zhang-Li spin-transfer terms
+using a collective variable approach. In the effective equations of motion the
+gradients of DMI play the role of a driving force which competes with current
+driving. All analytical predictions are confirmed by numerical simulations.",2004.02175v1
+2020-05-03,Philosophy-Guided Mathematical Formalism for Complex Systems Modelling,"We recently presented the so-called allagmatic method, which includes a
+system metamodel providing a framework for describing, modelling, simulating,
+and interpreting complex systems. Its development and programming was guided by
+philosophy, especially by Gilbert Simondon's philosophy of individuation,
+Alfred North Whitehead's philosophy of organism, and concepts from cybernetics.
+Here, a mathematical formalism is presented to better describe and define the
+system metamodel of the allagmatic method, thereby further generalising it and
+extending its reach to a more formal treatment and allowing more theoretical
+studies. By using the formalism, an example for such a further study is
+provided with mathematical definitions and proofs for model creation and
+equivalence of cellular automata and artificial neural networks.",2005.01192v5
+2020-05-07,"A closer look at the non-Hopfianness of $BS(2,3)$","The Baumslag-Solitar group $BS(2,3)$, is a so-called non-Hopfian group,
+meaning that it has an epimorphism $\phi$ onto itself, that is not injective.
+In particular this is equivalent to saying that $BS(2,3)$ has a non-trivial
+quotient that is isomorphic to itself. As a consequence the Cayley graph of
+$BS(2,3)$ has a quotient that is isomorphic to itself up to change of
+generators. We describe this quotient on the graph-level and take a closer look
+at the most common epimorphism $\phi$. We show its kernel is a free group of
+infinite rank with an explicit set of generators. Finally we show how $\phi$
+appears as a morphism on fundamental groups induced by some continuous map.
+This point of view was communicated to the author by Gilbert Levitt.",2005.03396v2
+2020-05-08,Project and Forget: Solving Large-Scale Metric Constrained Problems,"Given a set of dissimilarity measurements amongst data points, determining
+what metric representation is most ""consistent"" with the input measurements or
+the metric that best captures the relevant geometric features of the data is a
+key step in many machine learning algorithms. Existing methods are restricted
+to specific kinds of metrics or small problem sizes because of the large number
+of metric constraints in such problems. In this paper, we provide an active set
+algorithm, Project and Forget, that uses Bregman projections, to solve metric
+constrained problems with many (possibly exponentially) inequality constraints.
+We provide a theoretical analysis of \textsc{Project and Forget} and prove that
+our algorithm converges to the global optimal solution and that the $L_2$
+distance of the current iterate to the optimal solution decays asymptotically
+at an exponential rate. We demonstrate that using our method we can solve large
+problem instances of three types of metric constrained problems: general weight
+correlation clustering, metric nearness, and metric learning; in each case,
+out-performing the state of the art methods with respect to CPU times and
+problem sizes.",2005.03853v2
+2020-05-27,The Kirillov model in families,"Let $F$ be a non-archimedean local field, let $k$ be an algebraically closed
+field of characteristic $\ell$ different from the residual characteristic of
+$F$, and let $A$ be a commutative Noetherian $W(k)$-algebra, where $W(k)$
+denotes the Witt vectors. Using the Rankin-Selberg functional equations and
+extending recent results of the second author, we show that if $V$ is an
+$A[\text{GL}_n(F)]$-module of Whittaker type, then the mirabolic restriction
+map on its Whittaker space is injective. This gives a new quick proof of the
+existence of Kirillov models for representations of Whittaker type, including
+complex representations, which generalizes to the $\ell$-modular and families
+setting, in contrast with the previous proofs. In the special case where
+$A=k=\overline{\mathbb{F}_{\ell}}$ and $V$ is irreducible generic, our result
+in particular answers a question of Vign\'eras from 1989.",2005.13484v3
+2020-05-29,An Explicit Formula for the Zero-Error Feedback Capacity of a Class of Finite-State Additive Noise Channels,"It is known that for a discrete channel with correlated additive noise, the
+ordinary capacity with or without feedback both equal $ \log q-\mathcal{H} (Z)
+$, where $ \mathcal{H}(Z) $ is the entropy rate of the noise process $ Z $ and
+$ q $ is the alphabet size. In this paper, a class of finite-state additive
+noise channels is introduced. It is shown that the zero-error feedback capacity
+of such channels is either zero or $C_{0f} =\log q -h (Z) $, where $ h (Z) $ is
+the {\em topological entropy} of the noise process. A topological condition is
+given when the zero-error capacity is zero, with or without feedback. Moreover,
+the zero-error capacity without feedback is lower-bounded by $ \log q-2 h (Z)
+$. We explicitly compute the zero-error feedback capacity for several examples,
+including channels with isolated errors and a Gilbert-Elliot channel.",2006.00892v1
+2020-06-01,BBN constraints on dark radiation isocurvature,"The existence of dark radiation that is completely decoupled from the
+standard model in the early Universe leaves open the possibility of an
+associated dark radiation isocurvature mode. We show that the presence of dark
+radiation isocurvature leads to spatial variation in the primordial abundances
+of helium and deuterium due to spatial variation in $N_{\rm eff}$ during Big
+Bang nucleosynthesis. We use the result to constrain the existence of such an
+isocurvature mode on scales down to $\sim 1$ Mpc scales. By measuring the
+excess variance in the primordial helium to hydrogen and deuterium to hydrogen
+ratio in different galaxies, we constrain the variance in average isocurvature
+in a galaxy to be less than $0.13/\Delta \bar{N}_{\rm eff}$ at 95\% confidence.
+Here $\Delta \bar{N}_{\rm eff}$ is the spatially averaged increase in $N_{\rm
+eff}$ due to the additional dark radiation component.",2006.01165v2
+2020-06-12,Enhanced Stability of Antiferromagnetic Skyrmion during Its Motion by Anisotropic Dzyaloshinskii Moriya Interaction,"Searching for new methods to enhance the stability of antiferromagnetic (AFM)
+skyrmion during its motion is an important issue for AFM spintronic devices.
+Herein, the spin polarized current-induced dynamics of a distorted AFM skyrmion
+is numerically studied, based on the Landau Lifshitz Gilbert simulations of the
+model with an anisotropic Dzyaloshinskii Moriya (DM) interaction. It is
+demonstrated that the DM interaction anisotropy induces the skyrmion
+deformation, which suppresses the distortion during the motion and enhances the
+stability of the skyrmion. Moreover, the effect of the DM interaction
+anisotropy on the skyrmion velocity is investigated in detail, and the
+simulated results are further explained by Thiele theory. This work unveils a
+promising strategy to enhance the stability and the maximum velocity of AFM
+skyrmion, benefiting future spintronic applications.",2006.06938v1
+2020-07-02,Spectral Methods for Ranking with Scarce Data,"Given a number of pairwise preferences of items, a common task is to rank all
+the items. Examples include pairwise movie ratings, New Yorker cartoon caption
+contests, and many other consumer preferences tasks. What these settings have
+in common is two-fold: a scarcity of data (it may be costly to get comparisons
+for all the pairs of items) and additional feature information about the items
+(e.g., movie genre, director, and cast). In this paper we modify a popular and
+well studied method, RankCentrality for rank aggregation to account for few
+comparisons and that incorporates additional feature information. This method
+returns meaningful rankings even under scarce comparisons. Using diffusion
+based methods, we incorporate feature information that outperforms
+state-of-the-art methods in practice. We also provide improved sample
+complexity for RankCentrality in a variety of sampling schemes.",2007.01346v1
+2020-07-23,High Precision Real Time Collision Detection,"Collision detection and collision avoidance are essential components in these
+systems for safe human-robot interactions. Robotics systems that can work
+""out-of-the-box"" without excessive amount of installation and calibration from
+the experts is highly ideal. For this, we propose a generic, high precision,
+collision detect system that only requires the unified robot description format
+(URDF) and is capable of running in real time. We extended the
+Gilbert-Johnson-Keerthi (GJK) algorithm by utilizing a geometrical approach to
+determine the distance between each rigid body in the environment and check for
+collisions. The proposed system's performance is shown by checking the
+self-collision of the KUKA LBR iiwa 7 R800 and the Mecademic Meca500. The
+performance is compared to the Flexible Collision Library (FCL).",2007.12045v2
+2020-08-10,Coherent spin qubit transport in silicon,"A fault-tolerant quantum processor may be configured using stationary qubits
+interacting only with their nearest neighbours, but at the cost of significant
+overheads in physical qubits per logical qubit. Such overheads could be reduced
+by coherently transporting qubits across the chip, allowing connectivity beyond
+immediate neighbours. Here we demonstrate high-fidelity coherent transport of
+an electron spin qubit between quantum dots in isotopically-enriched silicon.
+We observe qubit precession in the inter-site tunnelling regime and assess the
+impact of qubit transport using Ramsey interferometry and quantum state
+tomography techniques. We report a polarization transfer fidelity of 99.97% and
+an average coherent transfer fidelity of 99.4%. Our results provide key
+elements for high-fidelity, on-chip quantum information distribution, as long
+envisaged, reinforcing the scaling prospects of silicon-based spin qubits.",2008.04020v2
+2020-08-20,Linear hash-functions and their applications to error detection and correction,"We describe and explore so-called linear hash functions and show how they can
+be used to build error detection and correction codes. The method can be
+applied for different types of errors (for example, burst errors). When the
+method is applied to a model where number of distorted letters is limited, the
+obtained estimate of its performance is slightly better than the known
+Varshamov-Gilbert bound. We also describe random code whose performance is
+close to the same boundary, but its construction is much simpler. In some cases
+the obtained methods are simpler and more flexible than the known ones. In
+particular, the complexity of the obtained error detection code and the
+well-known CRC code is close, but the proposed code, unlike CRC, can detect
+with certainty errors whose number does not exceed a predetermined limit.",2008.08955v1
+2020-08-27,Electrical conductivity of the quark-gluon plasma: perspective from lattice QCD,"A discussion on the electrical conductivity of the quark-gluon plasma as
+determined by lattice QCD is given. After a reminder of basic definitions and
+expectations, various methods for spectral reconstruction are reviewed,
+including the use of Ans\""atze and sum rules, the Maximum Entropy and
+Backus-Gilbert methods, and Tikhonov regularisation. A comprehensive overview
+of lattice QCD results obtained so far is given, including a comparison of the
+different lattice formulations. A noticeable consistency for the conductivities
+obtained is seen, in spite of the differences in the lattice setups and
+spectral reconstruction methods. It is found that in the case of quenched QCD
+little temperature dependence of $\sigma/T$ is seen in the temperature range
+investigated, while for QCD with dynamical quarks a reduction of $\sigma/T$ in
+the vicinity of the thermal crossover is observed, compared to its value in the
+QGP. Several open questions are posed at the end.",2008.12326v1
+2020-09-02,Heterobilayer moiré magnets: moiré skyrmions and the commensurate-incommensurate transition,"We study untwisted heterobilayers of ferromagnetic and antiferromagnetic van
+der Waals materials, with in particular a Dzyaloshinskii-Moriya interaction in
+the ferromagnetic layer. A continuum low energy field theory is utilized to
+study such systems. We develop a phase diagram as a function of the strength of
+inter-layer exchange and Dzyaloshinskii-Moriya interactions, combining
+perturbative and strong coupling analyses with numerical simulations using
+Landau-Lifshitz-Gilbert equations. Various moir\'e-periodic commensurate phases
+are found, and the commensurate-incommensurate transition is discussed. Among
+the commensurate phases, we observe an interesting skyrmion lattice phase
+wherein each moir\'e unit cell hosts one skyrmion.",2009.00860v3
+2020-09-04,5-Dimensional Space-Periodic Solutions of the Static Vacuum Einstein Equations,"An affirmative answer is given to a conjecture of Myers concerning the
+existence of 5-dimensional regular static vacuum solutions that balance an
+infinite number of black holes, which have Kasner asymptotics. A variety of
+examples are constructed, having different combinations of ring $S^1\times S^2$
+and sphere $S^3$ cross-sectional horizon topologies. Furthermore, we show the
+existence of 5-dimensional vacuum solitons with Kasner asymptotics. These are
+regular static space-periodic vacuum spacetimes devoid of black holes.
+Consequently, we also obtain new examples of complete Riemannian manifolds of
+nonnegative Ricci curvature in dimension 4, and zero Ricci curvature in
+dimension 5, having arbitrarily large as well as infinite second Betti number.",2009.01999v2
+2020-09-24,Quarantined! Examining the Effects of a Community-Wide Moderation Intervention on Reddit,"Should social media platforms override a community's self-policing when it
+repeatedly break rules? What actions can they consider? In light of this
+debate, platforms have begun experimenting with softer alternatives to outright
+bans. We examine one such intervention called quarantining, that impedes direct
+access to and promotion of controversial communities. Specifically, we present
+two case studies of what happened when Reddit quarantined the influential
+communities r/TheRedPill (TRP) and r/The_Donald (TD). Using over 85M Reddit
+posts, we apply causal inference methods to examine the quarantine's effects on
+TRP and TD. We find that the quarantine made it more difficult to recruit new
+members: new user influx to TRP and TD decreased by 79.5% and 58%,
+respectively. Despite quarantining, existing users' misogyny and racism levels
+remained unaffected. We conclude by reflecting on the effectiveness of this
+design friction in limiting the influence of toxic communities and discuss
+broader implications for content moderation.",2009.11483v3
+2020-10-24,Hunting for Dark Matter Subhalos in Strong Gravitational Lensing with Neural Networks,"Dark matter substructures are interesting since they can reveal the
+properties of dark matter. Collisionless N-body simulations of cold dark matter
+show more substructures compared with the population of dwarf galaxy satellites
+observed in our local group. Therefore, understanding the population and
+property of subhalos at cosmological scale would be an interesting test for
+cold dark matter. In recent years, it has become possible to detect individual
+dark matter subhalos near images of strongly lensed extended background
+galaxies. In this work, we discuss the possibility of using deep neural
+networks to detect dark matter subhalos, and showing some preliminary results
+with simulated data. We found that neural networks not only show promising
+results on detecting multiple dark matter subhalos, but also learn to reject
+the subhalos on the lensing arc of a smooth lens where there is no subhalo.",2010.12960v2
+2020-10-28,Skyrmions Near Defects,"We study the impact of an exchange-reducing defect on a skyrmion for a thin
+film of finite thickness. Attraction of the skyrmion to a defect is
+demonstrated in a lattice model by computing the micromagnetic energy
+accounting for the exchange, Dzyaloshinskii-Moriya interaction, magnetic
+anisotropy, and dipole-dipole coupling. The spiraling dynamics of the skyrmion
+towards the defect is illustrated by solving numerically the full
+Landau-Lifshitz-Gilbert equations on a lattice and, independently, the Thiele
+equation, with the two methods in agreement with each other. We find that the
+skyrmion deforms when approaching the defect. Deformation is small in the
+parameter space far from the phase boundary that determines stability of
+skyrmions. It increases dramatically near the phase boundary, leading to the
+transformation of the skyrmion by the defect into a snake-like magnetic domain.",2010.14683v2
+2020-10-29,Micromagnetics of thin films in the presence of Dzyaloshinskii-Moriya interaction,"In this paper, we study the thin-film limit of the micromagnetic energy
+functional in the presence of bulk Dzyaloshinskii-Moriya interaction (DMI). Our
+analysis includes both a stationary $\Gamma$-convergence result for the
+micromagnetic energy, as well as the identification of the asymptotic behavior
+of the associated Landau-Lifshitz-Gilbert equation. In particular, we prove
+that, in the limiting model, part of the DMI term behaves like the projection
+of the magnetic moment onto the normal to the film, contributing this way to an
+increase in the shape anisotropy arising from the magnetostatic self-energy.
+Finally, we discuss a convergent finite element approach for the approximation
+of the time-dependent case and use it to numerically compare the original
+three-dimensional model with the two-dimensional thin-film limit.",2010.15541v1
+2020-11-11,Role of impurity clusters for the current-driven motion of magnetic Skyrmions,"We study how impurities influence the current-induced dynamics of magnetic
+Skyrmions moving in a racetrack geometry. For this, we solve numerically the
+generalized Landau-Lifshitz-Gilbert equation extended by the current-induced
+spin transfer torque. In particular, we investigate two classes of impurities,
+non-conducting and magnetic impurities. The former are magnetically rigid
+objects and yield to an inhomogeneous current density over the racetrack which
+we determine separately by solving the fundamental electrostatic equations. In
+contrast, magnetic impurities leave the applied current density homogeneous
+throughout the stripe. Depending on parameters, we observe four different
+scenarios of Skyrmion motions in the presence of disorder, the Skyrmion decay,
+the pinning, the creation of additional Skyrmions, and ordinary Skyrmion
+passage. We calculate and discuss phase diagrams in dependence of the impurity
+concentration and radii of the impurities.",2011.06027v1
+2020-11-12,Communication Efficient Coresets for Maximum Matching,"In this paper we revisit the problem of constructing randomized composable
+coresets for bipartite matching. In this problem the input graph is randomly
+partitioned across $k$ players, each of which sends a single message to a
+coordinator, who then must output a good approximation to the maximum matching
+in the input graph. Assadi and Khanna gave the first such coreset, achieving a
+$1/9$-approximation by having every player send a maximum matching, i.e. at
+most $n/2$ words per player. The approximation factor was improved to $1/3$ by
+Bernstein et al.
+  In this paper, we show that the matching skeleton construction of Goel,
+Kapralov and Khanna, which is a carefully chosen (fractional) matching, is a
+randomized composable coreset that achieves a $1/2-o(1)$ approximation using at
+most $n-1$ words of communication per player. We also show an upper bound of
+$2/3+o(1)$ on the approximation ratio achieved by this coreset.",2011.06481v1
+2020-11-17,Thermally assisted magnetization reversal of a magnetic nanoparticle driven by a down-chirp microwave field pulse,"It has been shown that a single-domain magnetic nanoparticle can be
+effectively switched by a linear down-chirp microwave field pulse (DCMWP) in
+zero temperature limit. However, finite temperature is ubiquitous in practice.
+Here, we study the effect of finite temperature on the DCMWP-induced
+magnetization reversal based on the stochastic Landau-Lifshitz-Gilbert
+equation. It is found that any one of the three controlling parameters of a
+DCMWP, i.e. the amplitude, chirp rate, or initial frequency, decreases with
+increasing temperature while the other two are fixed. The maximal temperature
+at which the reversal can happen increases with enlarging the system size.
+These phenomena are related to the facts that the energy barrier induced by
+anisotropy increases with the system volume, and the effective magnetization
+decreases with temperature. We also provide a set of optimal parameters for
+practical realization of our proposal. These findings may provide a way to
+realize low-cost and fast magnetization reversal with a wide operating
+temperature.",2011.08610v2
+2020-11-17,Sum-frequency excitation of coherent magnons,"Coherent excitation of magnons is conventionally achieved through Raman
+scattering processes, in which the difference-frequency components of the
+driving field are resonant with the magnon energy. Here, we describe mechanisms
+by which the sum-frequency components of the driving field can be used to
+coherently excite magnons through two-particle absorption processes. We use the
+Landau-Lifshitz-Gilbert formalism to compare the spin-precession amplitudes
+that different types of impulsive stimulated and ionic Raman scattering
+processes and their sum-frequency counterparts induce in an antiferromagnetic
+model system. We show that sum-frequency mechanisms enabled by linearly
+polarized driving fields yield excitation efficiencies comparable or larger
+than established Raman techniques, while elliptical polarizations produce only
+weak and circularly polarizations no sum-frequency components at all. The
+mechanisms presented here complete the map for dynamical spin control by the
+means of Raman-type processes.",2011.08730v1
+2020-11-26,3D Nanomagnetism in Low Density Interconnected Nanowire Networks,"Free-standing, interconnected metallic nanowire networks with density as low
+as 40 mg/cm^{3} have been achieved over cm-scale areas, using electrodeposition
+into polycarbonate membranes that have been ion-tracked at multiple angles.
+Networks of interconnected magnetic nanowires further provide an exciting
+platform to explore 3-dimensional nanomagnetism, where their structure,
+topology and frustration may be used as additional degrees of freedom to tailor
+the materials properties. New magnetization reversal mechanisms in cobalt
+networks are captured by the first-order reversal curve method, which
+demonstrate the evolution from strong demagnetizing dipolar interactions to
+intersections-mediated domain wall pinning and propagation, and eventually to
+shape-anisotropy dominated magnetization reversal. These findings open up new
+possibilities for 3-dimensional integrated magnetic devices for memory, complex
+computation, and neuromorphics.",2011.13468v2
+2020-12-02,Quantum Annealed Criticality: A Scaling Description,"Experimentally there exist many materials with first-order phase transitions
+at finite temperature that display quantum criticality. Classically, a
+strain-energy density coupling is known to drive first-order transitions in
+compressible systems, and here we generalize this Larkin-Pikin mechanism to the
+quantum case. We show that if the T=0 system lies above its upper critical
+dimension, the line of first-order transitions ends in a ""quantum annealed
+critical point"" where zero-point fluctuations restore the underlying
+criticality of the order parameter. The generalized Larkin-Pikin phase diagram
+is presented and experimental consequences are discussed.",2012.01601v1
+2020-12-04,Rethinking movie genre classification with fine-grained semantic clustering,"Movie genre classification is an active research area in machine learning.
+However, due to the limited labels available, there can be large semantic
+variations between movies within a single genre definition. We expand these
+'coarse' genre labels by identifying 'fine-grained' semantic information within
+the multi-modal content of movies. By leveraging pre-trained 'expert' networks,
+we learn the influence of different combinations of modes for multi-label genre
+classification. Using a contrastive loss, we continue to fine-tune this
+'coarse' genre classification network to identify high-level intertextual
+similarities between the movies across all genre labels. This leads to a more
+'fine-grained' and detailed clustering, based on semantic similarities while
+still retaining some genre information. Our approach is demonstrated on a newly
+introduced multi-modal 37,866,450 frame, 8,800 movie trailer dataset,
+MMX-Trailer-20, which includes pre-computed audio, location, motion, and image
+embeddings.",2012.02639v3
+2020-12-04,Nutation in antiferromagnetic resonance,"The effect of inertial spin dynamics is compared between ferromagnetic,
+antiferromagnetic and ferrimagnetic systems. The linear response to an
+oscillating external magnetic field is calculated within the framework of the
+inertial Landau--Lifshitz--Gilbert equation using analytical theory and
+computer simulations. Precession and nutation resonance peaks are identified,
+and it is demonstrated that the precession frequencies are reduced by the spin
+inertia, while the lifetime of the excitations is enhanced. The interplay
+between precession and nutation is found to be the most prominent in
+antiferromagnets, where the timescale of the exchange-driven sublattice
+dynamics is comparable to inertial relaxation times. Consequently,
+antiferromagnetic resonance techniques should be better suited for the search
+for intrinsical inertial spin dynamics on ultrafast timescales than
+ferromagnetic resonance.",2012.02790v3
+2020-12-14,Thermally induced spin torque and domain wall motion in superconductor/antiferromagnetic insulator bilayers,"We theoretically investigate domain wall motion in an antiferromagnetic
+insulator layer caused by thermally generated spin currents in an adjacent
+spin-split superconductor layer. An uncompensated antiferromagnet interface
+enables the two crucial ingredients underlying the mechanism - spin splitting
+in the superconductor and absorption of spin currents by the antiferromagnet.
+Treating the superconductor using the quasiclassical theory and the
+antiferromagnet via Landau-Lifshitz-Gilbert description, we find domain wall
+propagation along the thermal gradient with relatively large velocities $\sim
+100$ m/s. Our proposal exploits the giant thermal response of spin-split
+superconductors in achieving large spin torques towards driving domain wall and
+other spin textures in antiferromagnets.",2012.07405v1
+2020-11-04,A note on the intuitionistic logic of false belief,"In this paper we analyse logic of false belief in intuitionistic setting.
+This logic, studied in its classical version by Steinsvold, Fan, Gilbert and
+Venturi, describes the following situation: a formula F is not satisfied in a
+given world, but we still believe in it (or we think that it should be
+accepted). Another interpretations are also possible: e.g. that we do not
+accept F but it is imposed on us by a kind of council or advisory board. From
+the mathematical point of view, the idea is expressed by an adequate form of
+modal operator W which is interpreted in relational frames with neighborhoods.
+We discuss monotonicity of forcing, soundness, completeness and several other
+issues. We present also some simple systems in which confirmation of previously
+accepted formula is modelled.",2012.08309v1
+2021-01-05,Efficient domain wall motion in asymmetric magnetic tunnel junctions with vertical current flow,"In this paper, we study the domain wall motion induced by vertical current
+flow in asymmetric magnetic tunnel junctions. The domain wall motion in the
+free layer is mainly dictated by the current-induced field-like torque acting
+on it. We show that as we increase the MTJ asymmetry, by considering dissimilar
+ferromagnetic contacts, a linear-in-voltage field-like torque behavior is
+accompanied by an enhancement in the domain wall displacement efficiency and a
+higher degree of bidirectional propagation. Our analysis is based on a
+combination of a quantum transport model and magnetization dynamics as
+described by the Landau-Lifshitz-Gilbert equation, along with comparison to the
+intrinsic characteristics of a benchmark in-plane current injection domain wall
+device.",2101.01581v1
+2021-01-12,Modeling of Thermal Magnetic Fluctuations in Nanoparticle Enhanced Magnetic Resonance Detection,"We present a systematic numerical modeling investigation of magnetization
+dynamics and thermal magnetic moment fluctuations of single magnetic domain
+nanoparticles in a configuration applicable to enhancing inductive magnetic
+resonance detection signal to noise ratio (SNR). Previous proposals for
+oriented anisotropic single magnetic domain nanoparticle amplification of
+magnetic flux in MRI coil focused only on the coil pick-up voltage signal
+enhancement. Here we extend the analysis to the numerical evaluation of the SNR
+by modeling the inherent thermal magnetic noise introduced into the detection
+coil by the insertion of such anisotropic nanoparticle-filled coil core. We
+utilize the Landau-Lifshitz-Gilbert equation under the Stoner-Wohlfarth single
+magnetic domain (macrospin) assumption to simulate the magnetization dynamics
+in such nanoparticles due to AC drive field as well as thermal noise. These
+simulations are used to evaluate the nanoparticle configurations and shape
+effects on enhancing SNR. Finally, we explore the effect of narrow band
+filtering of the broadband magnetic moment thermal fluctuation noise on the
+SNR. Our results provide the impetus for relatively simple modifications to
+existing MRI systems for achieving enhanced detection SNR in scanners with
+modest polarizing magnetic fields.",2101.04649v1
+2021-01-20,Spin-current mediated exchange coupling in MgO-based magnetic tunnel junctions,"Heterostructures composed of ferromagnetic layers that are mutually
+interacting through a nonmagnetic spacer are at the core of magnetic sensor and
+memory devices. In the present study, layer-resolved ferromagnetic resonance
+was used to investigate the coupling between the magnetic layers of a
+Co/MgO/Permalloy magnetic tunnel junction. Two magnetic resonance peaks were
+observed for both magnetic layers, as probed at the Co and Ni L3 x-ray
+absorption edges, showing a strong interlayer interaction through the
+insulating MgO barrier. A theoretical model based on the
+Landau-Lifshitz-Gilbert-Slonczewski equation was developed, including exchange
+coupling and spin pumping between the magnetic layers. Fits to the experimental
+data were carried out, both with and without a spin pumping term, and the
+goodness of the fit was compared using a likelihood ratio test. This rigorous
+statistical approach provides an unambiguous proof of the existence of
+interlayer coupling mediated by spin pumping.",2101.08157v1
+2021-01-27,Numerical simulation of the viral entry into a cell driven by receptor diffusion,"The present study focuses on the receptor driven endocytosis typical of viral
+entry into a cell. A locally increased density of receptors at the time of
+contact between the cell and the virus is necessary in this case. The virus is
+considered as a substrate with fixed receptors on its surface, whereas the
+receptors of the host cell are free to move over its membrane, allowing a local
+change in their concentration. In the contact zone the membrane inflects and
+forms an envelope around the virus. The created vesicle imports its cargo into
+the cell. This paper assumes the diffusion equation accompanied by boundary
+conditions requiring the conservation of binders to describe the process.
+Moreover, it introduces a condition defining the energy balance at the front of
+the adhesion zone. The latter yields the upper limit for the size of virus
+which can be engulfed by the cell membrane. The described moving boundary
+problem in terms of the binder density and the velocity of the adhesion front
+is well posed and numerically solved by using the finite difference method. The
+illustrative examples have been chosen to show the influence of the process
+parameters on the initiation and the duration of the process.",2101.11515v1
+2021-02-04,AI Development for the Public Interest: From Abstraction Traps to Sociotechnical Risks,"Despite interest in communicating ethical problems and social contexts within
+the undergraduate curriculum to advance Public Interest Technology (PIT) goals,
+interventions at the graduate level remain largely unexplored. This may be due
+to the conflicting ways through which distinct Artificial Intelligence (AI)
+research tracks conceive of their interface with social contexts. In this paper
+we track the historical emergence of sociotechnical inquiry in three distinct
+subfields of AI research: AI Safety, Fair Machine Learning (Fair ML) and
+Human-in-the-Loop (HIL) Autonomy. We show that for each subfield, perceptions
+of PIT stem from the particular dangers faced by past integration of technical
+systems within a normative social order. We further interrogate how these
+histories dictate the response of each subfield to conceptual traps, as defined
+in the Science and Technology Studies literature. Finally, through a
+comparative analysis of these currently siloed fields, we present a roadmap for
+a unified approach to sociotechnical graduate pedagogy in AI.",2102.04255v1
+2021-02-15,An In-Depth Investigation of the Performance Characteristics of Hyperledger Fabric,"Private permissioned blockchains are deployed in ever greater numbers to
+facilitate cross-organizational processes in various industries, particularly
+in supply chain management. One popular example of this trend is Hyperledger
+Fabric. Compared to public permissionless blockchains, it promises improved
+performance and provides certain features that address key requirements of
+enterprises. However, also permissioned blockchains are still not as scalable
+as centralized systems, and due to the scarcity of theoretical results and
+empirical data, their real-world performance cannot be predicted with the
+necessary precision. We intend to address this issue by conducting an in-depth
+performance analysis of Hyperledger Fabric. The paper presents a detailed
+compilation of various performance characteristics using an enhanced version of
+the Distributed Ledger Performance Scan (DLPS). Researchers and practitioners
+alike can use the various performance properties identified and discussed as
+guidelines to better configure and implement their Hyperledger Fabric network.
+Likewise, they are encouraged to use the DLPS framework to conduct their
+measurements.",2102.07731v2
+2021-02-18,On isodual double Toeplitz codes,"Double Toeplitz (shortly DT) codes are introduced here as a generalization of
+double circulant codes. We show that such a code is isodual, hence formally
+self-dual. Self-dual DT codes are characterized as double circulant or double
+negacirculant. Likewise, even DT binary codes are characterized as double
+circulants. Numerical examples obtained by exhaustive search show that the
+codes constructed have best-known minimum distance, up to one unit, amongst
+formally self-dual codes, and sometimes improve on the known values. Over
+$\F_4$ an explicit construction of DT codes, based on quadratic residues in a
+prime field, performs equally well. We show that DT codes are asymptotically
+good over $\F_q$. Specifically, we construct DT codes arbitrarily close to the
+asymptotic varshamov-Gilbert bound for codes of rate one half.",2102.09233v1
+2021-02-20,Design of Ciphers based on the Geometric Structure of the Möbius Plane,"Till now geometric structures don't play a major role in cryptography.
+Gilbert, MacWilliams and Sloane introduced in 1974 an authentication scheme in
+the projective plane and showed its perfectness in the sense of the definition
+of Shannon. In this paper we will show that this authentication scheme also
+fulfills the requirement of completeness according to Kam and Davida and we
+will extend the application of geometric structures in cryptography by
+introducing an encryption scheme in the M\""obius plane. We will further examine
+its properties, showing that it also fulfills the requirement of completeness
+and Shannon's requirement of perfectness in first approximation. The results of
+this paper can be used to define similar encryption schemes in the circle
+geometries of Laguerre and Minkowski.",2102.10321v2
+2021-03-02,Struwe-like solutions for an evolutionary model of magnetoviscoelastic fluids,"In this work we investigate the existence and uniqueness of Struwe-like
+solutions for a system of partial differential equations modeling the dynamics
+of magnetoviscoelastic fluids. The considered system couples a Navier-Stokes
+type equation with a dissipative equation for the deformation tensor and a
+Landau-Lifshitz-Gilbert type equation for the magnetization field. The main
+purpose is to establish a well-posedness theory in a two-dimensional periodic
+domain under standard assumption of critical regularity for the (possibly
+large) initial data. We prove that the considered weak solutions are everywhere
+smooth, except for a discrete set of time values. The proof of the uniqueness
+is based on suitable energy estimates for the solutions within a functional
+framework which is less regular than the one of the Struwe energy level. These
+estimates rely on several techniques of harmonic analysis and paradifferential
+calculus.",2103.01647v1
+2021-03-07,Design of Ciphers based on the Geometric Structure of the Laguerre and Minkowski Planes,"Till now geometric structures don't play a major role in cryptography.
+Gilbert, MacWilliams and Sloane introduced an authentication scheme in the
+projective plane and showed its perfectness in the sense of Shannon. In
+arXiv:2102.10321 we introduced an encryption scheme in the M\""obius plane and
+showed that it fulfills Shannon's requirement of perfectness in first
+approximation and also the requirement of completeness according to Kam and
+Davida. In this paper we will apply a similar approach to define encryption
+schemes in the geometries of the Laguerre plande and the Minkowski plane. We
+will show that the encryption scheme in the Laguerre geometry meets Shannon's
+requirement of perfectness sharp and that the encryption scheme in the
+Minkowski geometry meets this requirement in first approximation. The Laguerre
+cipher also fulfills the requirement of completeness according to Kam and
+Davida.",2103.04428v1
+2021-03-09,An atomic perspective on the serpentine-chlorite solid-state transformation,"Serpentine minerals are important components of metamorphic rocks and
+promising geo-materials for nanotechnology. Lizardite, the most abundant
+serpentine mineral, can be transformed into chlorite during metamorphism. This
+intriguing phase transformation should affect the deformation behavior during
+aseismic creep and slow slip at the base of the subduction zone, but has not
+been understood structurally and chemically at the atomic scale. Here we
+visualized cations and oxygen atoms using the state-of-the-art low-dose
+scanning transmission electron microscopy and found that restructuring mainly
+involves the synergistic migration of tetrahedral cations and oxygen anions,
+coupled with the migration of octahedral trivalent cations into the
+brucite-like interlayer. Further, we show that different serpentine polytypes
+result in distinct regular interstratifications of serpentine and chlorite. Our
+results clarify the long-standing puzzle of how solid-state layer silicate
+transformations occur and lead to long-period ordered structures.",2103.05210v1
+2021-03-13,On Bounds for Ring-Based Coding Theory,"Coding Theory where the alphabet is identified with the elements of a ring or
+a module has become an important research topic over the last 30 years. Such
+codes over rings had important applications and many interesting mathematical
+problems are related to this line of research.
+  It has been well established, that with the generalization of the algebraic
+structure to rings there is a need to also generalize the underlying metric
+beyond the usual Hamming weight used in traditional coding theory over finite
+fields.
+  This paper introduces a new weight, called the overweight, which can be seen
+as a generalization of the Lee weight on the integers modulo $4$. For this new
+weight we provide a number of well-known bounds, like a Plotkin bound, a
+sphere-packing bound, and a Gilbert-Varshamov bound. A further highlight is the
+proof of a Johnson bound for the homogeneous weight on a general finite
+Frobenius ring.",2103.07749v2
+2021-03-17,ALADIN: All Layer Adaptive Instance Normalization for Fine-grained Style Similarity,"We present ALADIN (All Layer AdaIN); a novel architecture for searching
+images based on the similarity of their artistic style. Representation learning
+is critical to visual search, where distance in the learned search embedding
+reflects image similarity. Learning an embedding that discriminates
+fine-grained variations in style is hard, due to the difficulty of defining and
+labelling style. ALADIN takes a weakly supervised approach to learning a
+representation for fine-grained style similarity of digital artworks,
+leveraging BAM-FG, a novel large-scale dataset of user generated content
+groupings gathered from the web. ALADIN sets a new state of the art accuracy
+for style-based visual search over both coarse labelled style data (BAM) and
+BAM-FG; a new 2.62 million image dataset of 310,000 fine-grained style
+groupings also contributed by this work.",2103.09776v1
+2021-03-23,A Massively Parallel Time-Domain Coupled Electrodynamics-Micromagnetics Solver,"We present a new, high-performance coupled electrodynamics-micromagnetics
+solver for full physical modeling of signals in microelectronic circuitry. The
+overall strategy couples a finite-difference time-domain (FDTD) approach for
+Maxwell's equations to a magnetization model described by the
+Landau-Lifshitz-Gilbert (LLG) equation. The algorithm is implemented in the
+Exascale Computing Project software framework, AMReX, which provides effective
+scalability on manycore and GPU-based supercomputing architectures.
+Furthermore, the code leverages ongoing developments of the Exascale
+Application Code, WarpX, primarily developed for plasma wakefield accelerator
+modeling. Our novel temporal coupling scheme provides second-order accuracy in
+space and time by combining the integration steps for the magnetic field and
+magnetization into an iterative sub-step that includes a trapezoidal
+discretization for the magnetization. The performance of the algorithm is
+demonstrated by the excellent scaling results on NERSC multicore and GPU
+systems, with a significant (59x) speedup on the GPU using a node-by-node
+comparison. We demonstrate the utility of our code by performing simulations of
+an electromagnetic waveguide and a magnetically tunable filter.",2103.12819v1
+2021-04-06,Geometry and Symmetry in Skyrmion Dynamics,"The uniform motion of chiral magnetic skyrmions induced by a spin-transfer
+torque displays an intricate dependence on the skyrmions' topological charge
+and shape. We reveal surprising patterns in this dependence through simulations
+of the Landau-Lifshitz-Gilbert equation with Zhang-Li torque and explain them
+through a geometric analysis of Thiele's equation. In particular, we show that
+the velocity distribution of topologically non-trivial skyrmions depends on
+their symmetry: it is a single circle for skyrmions of high symmetry and a
+family of circles for low-symmetry configurations. We also show that the
+velocity of the topologically trivial skyrmions, previously believed to be the
+fastest objects, can be surpassed, for instance, by antiskyrmions. The
+generality of our approach suggests the validity of our results for exchange
+frustrated magnets, bubble materials, and others.",2104.02342v1
+2021-04-06,Diffusion of a magnetic skyrmion in 2-dimensional space,"Two-dimensional magnetic skyrmions are particle-like magnetic domains in
+magnetic thin films. The kinetic property of the magnetic skyrmions at finite
+temperature is well described by the Thiele equation, including a stochastic
+field and a finite mass. In this paper, the validity of the constant-mass
+approximation is examined by comparing the Fourier spectrum of Brownian motions
+described by the Thiele equation and the Landau-Lifshitz-Gilbert equation.
+Then, the 4-dimensional Fokker-Planck equation is derived from the Thiele
+equation with a mass-term. Consequently, an expression of the diffusion flow
+and diffusion constant in a tensor form is derived, extending Chandrasekhar's
+method for Thiele dynamics.",2104.02345v2
+2021-04-08,Computation and Bribery of Voting Power in Delegative Simple Games,"Following Zhang and Grossi~(AAAI 2021), we study in more depth a variant of
+weighted voting games in which agents' weights are induced by a transitive
+support structure. This class of simple games is notably well suited to study
+the relative importance of agents in the liquid democracy framework. We first
+propose a pseudo-polynomial time algorithm to compute the Banzhaf and
+Shapley-Shubik indices for this class of game. Then, we study a bribery
+problem, in which one tries to maximize/minimize the voting power/weight of a
+given agent by changing the support structure under a budget constraint. We
+show that these problems are computationally hard and provide several
+parameterized complexity results.",2104.03692v2
+2021-05-10,Role of higher-order effects in spin-misalignment small-angle neutron scattering of high-pressure torsion nickel,"Magnetic-field-dependent unpolarized small-angle neutron scattering (SANS)
+experiments demonstrate that high-pressure torsion (HPT) straining induces spin
+misalignments in pure Ni, which persist in magnetic fields up to 4 T. The
+spin-misalignment scattering patterns are elongated perpendicular to the
+applied magnetic field due to an unusual predominant longitudinal
+$sin^2(\theta)$-type angular anisotropy. Such a contribution cannot be
+explained by the conventional second order (in spin misalignment amplitude)
+micromagnetic SANS theory in the approach-to-saturation regime, nor can its
+magnitude relative to the other features of the cross sections by the third
+order micromagnetic SANS theory. This indicates that the high-density of
+crystal defects induced via HPT straining in Ni makes such higher-order effects
+in the micromagnetic SANS cross sections observable.",2105.04167v1
+2021-04-26,Axes for Sociotechnical Inquiry in AI Research,"The development of artificial intelligence (AI) technologies has far exceeded
+the investigation of their relationship with society. Sociotechnical inquiry is
+needed to mitigate the harms of new technologies whose potential impacts remain
+poorly understood. To date, subfields of AI research develop primarily
+individual views on their relationship with sociotechnics, while tools for
+external investigation, comparison, and cross-pollination are lacking. In this
+paper, we propose four directions for inquiry into new and evolving areas of
+technological development: value--what progress and direction does a field
+promote, optimization--how the defined system within a problem formulation
+relates to broader dynamics, consensus--how agreement is achieved and who is
+included in building it, and failure--what methods are pursued when the problem
+specification is found wanting. The paper provides a lexicon for sociotechnical
+inquiry and illustrates it through the example of consumer drone technology.",2105.06551v1
+2021-05-21,$\mathbb{F}_q$-zeros of sparse trivariate polynomials and toric 3-fold codes,"For a given lattice polytope $P$ in $\mathbb{R}^3$, consider the space
+$\mathcal{L}_P$ of trivariate polynomials over a finite field $\mathbb{F}_q$,
+whose Newton polytopes are contained in $P$. We give an upper bound for the
+maximum number of $\mathbb{F}_q$-zeros of polynomials in $\mathcal{L}_P$ in
+terms of the Minkowski length of $P$ and $q$, the size of the field.
+Consequently, this produces lower bounds for the minimum distance of toric
+codes defined by evaluating elements of $\mathcal{L}_P$ at the points of the
+algebraic torus $(\mathbb{F}_q^*)^3$. Our approach is based on understanding
+factorizations of polynomials in $\mathcal{L}_P$ with the largest possible
+number of non-unit factors. The related combinatorial result that we obtain is
+a description of Minkowski sums of lattice polytopes contained in $P$ with the
+largest possible number of non-trivial summands.",2105.10071v2
+2021-05-24,Spatio-temporal dynamics of voltage-induced resistance transition in the double-exchange model,"We present multi-scale dynamical simulations of voltage-induced
+insulator-to-metal transition in the double exchange model, a canonical example
+of itinerant magnet and correlated electron systems. By combining
+nonequilibrium Green's function method with large-scale Landau-Lifshitz-Gilbert
+dynamics, we show that the transition from an antiferromagnetic insulator to
+the low-resistance state is initiated by the nucleation of a thin ferromagnetic
+conducting layer at the anode. The metal-insulator interface separating the two
+phases is then driven toward the opposite electrode by the voltage stress,
+giving rise to a growing metallic region. We further show that the initial
+transformation kinetics is well described by the Kolmogorov-Avrami-Ishibashi
+model with an effective spatial-dimension that depends on the applied voltage.
+Implications of our findings for the resistive switching in colossal
+magnetoresistant materials are also discussed.",2105.11076v2
+2021-05-26,"High-speed programmable photonic circuits in a cryogenically compatible, visible-NIR 200 mm CMOS architecture","Recent advances in photonic integrated circuits (PICs) have enabled a new
+generation of ""programmable many-mode interferometers"" (PMMIs) realized by
+cascaded Mach Zehnder Interferometers (MZIs) capable of universal
+linear-optical transformations on N input-output optical modes. PMMIs serve
+critical functions in photonic quantum information processing, quantum-enhanced
+sensor networks, machine learning and other applications. However, PMMI
+implementations reported to date rely on thermo-optic phase shifters, which
+limit applications due to slow response times and high power consumption. Here,
+we introduce a large-scale PMMI platform, based on a 200 mm CMOS process, that
+uses aluminum nitride (AlN) piezo-optomechanical actuators coupled to silicon
+nitride (SiN) waveguides, enabling low-loss propagation with phase modulation
+at greater than 100 MHz in the visible to near-infrared wavelengths. Moreover,
+the vanishingly low holding-power consumption of the piezo-actuators enables
+these PICs to operate at cryogenic temperatures, paving the way for a fully
+integrated device architecture for a range of quantum applications.",2105.12531v1
+2021-05-27,On the Complexity of Load Balancing in Dynamic Networks,"In the load balancing problem, each node in a network is assigned a load, and
+the goal is to equally distribute the loads among the nodes, by preforming
+local load exchanges. While load balancing was extensively studied in static
+networks, only recently a load balancing algorithm for dynamic networks with a
+bounded convergence time was presented. In this paper, we further study the
+time complexity of load balancing in the context of dynamic networks.
+  First, we show that randomness is not necessary, and present a deterministic
+algorithm which slightly improves the running time of the previous algorithm,
+at the price of not being matching-based. Then, we consider integral loads,
+i.e., loads that cannot be split indefinitely, and prove that no matching-based
+algorithm can have a bounded convergence time for this case.
+  To circumvent both this impossibility result, and a known one for the
+non-integral case, we apply the method of smoothed analysis, where random
+perturbations are made over the worst-case choices of network topologies. We
+show both impossibility results do not hold under this kind of analysis,
+suggesting that load-balancing in real world systems might be faster than the
+lower bounds suggest.",2105.13194v1
+2021-06-09,A Compact Model for Scalable MTJ Simulation,"This paper presents a physics-based modeling framework for the analysis and
+transient simulation of circuits containing Spin-Transfer Torque (STT) Magnetic
+Tunnel Junction (MTJ) devices. The framework provides the tools to analyze the
+stochastic behavior of MTJs and to generate Verilog-A compact models for their
+simulation in large VLSI designs, addressing the need for an industry-ready
+model accounting for real-world reliability and scalability requirements.
+Device dynamics are described by the Landau-Lifshitz-Gilbert-Slonczewsky
+(s-LLGS ) stochastic magnetization considering Voltage-Controlled Magnetic
+Anisotropy (VCMA) and the non-negligible statistical effects caused by thermal
+noise. Model behavior is validated against the OOMMF magnetic simulator and its
+performance is characterized on a 1-Mb 28 nm Magnetoresistive-RAM (MRAM) memory
+product.",2106.04976v1
+2021-06-14,Can Explainable AI Explain Unfairness? A Framework for Evaluating Explainable AI,"Many ML models are opaque to humans, producing decisions too complex for
+humans to easily understand. In response, explainable artificial intelligence
+(XAI) tools that analyze the inner workings of a model have been created.
+Despite these tools' strength in translating model behavior, critiques have
+raised concerns about the impact of XAI tools as a tool for `fairwashing` by
+misleading users into trusting biased or incorrect models. In this paper, we
+created a framework for evaluating explainable AI tools with respect to their
+capabilities for detecting and addressing issues of bias and fairness as well
+as their capacity to communicate these results to their users clearly. We found
+that despite their capabilities in simplifying and explaining model behavior,
+many prominent XAI tools lack features that could be critical in detecting
+bias. Developers can use our framework to suggest modifications needed in their
+toolkits to reduce issues likes fairwashing.",2106.07483v1
+2021-06-17,Density of Free Modules over Finite Chain Rings,"In this paper we focus on modules over a finite chain ring $\mathcal{R}$ of
+size $q^s$. We compute the density of free modules of $\mathcal{R}^n$, where we
+separately treat the asymptotics in $n,q$ and $s$. In particular, we focus on
+two cases: one where we fix the length of the module and one where we fix the
+rank of the module. In both cases, the density results can be bounded by the
+Andrews-Gordon identities. We also study the asymptotic behaviour of modules
+generated by random matrices over $\mathcal{R}$. Since linear codes over
+$\mathcal{R}$ are submodules of $\mathcal{R}^n$ we get direct implications for
+coding theory. For example, we show that random codes achieve the
+Gilbert-Varshamov bound with high probability.",2106.09403v2
+2021-06-28,Combinatorial BLAS 2.0: Scaling combinatorial algorithms on distributed-memory systems,"Combinatorial algorithms such as those that arise in graph analysis, modeling
+of discrete systems, bioinformatics, and chemistry, are often hard to
+parallelize. The Combinatorial BLAS library implements key computational
+primitives for rapid development of combinatorial algorithms in
+distributed-memory systems. During the decade since its first introduction, the
+Combinatorial BLAS library has evolved and expanded significantly.
+  This paper details many of the key technical features of Combinatorial BLAS
+version 2.0, such as communication avoidance, hierarchical parallelism via
+in-node multithreading, accelerator support via GPU kernels, generalized
+semiring support, implementations of key data structures and functions, and
+scalable distributed I/O operations for human-readable files. Our paper also
+presents several rules of thumb for choosing the right data structures and
+functions in Combinatorial BLAS 2.0, under various common application
+scenarios.",2106.14402v1
+2021-07-01,From Epidemic to Pandemic Modelling,"We present a methodology for systematically extending epidemic models to
+multilevel and multiscale spatio-temporal pandemic ones. Our approach builds on
+the use of coloured stochastic and continuous Petri nets facilitating the sound
+component-based extension of basic SIR models to include population
+stratification and also spatio-geographic information and travel connections,
+represented as graphs, resulting in robust stratified pandemic metapopulation
+models. This method is inherently easy to use, producing scalable and reusable
+models with a high degree of clarity and accessibility which can be read either
+in a deterministic or stochastic paradigm. Our method is supported by a
+publicly available platform PetriNuts; it enables the visual construction and
+editing of models; deterministic, stochastic and hybrid simulation as well as
+structural and behavioural analysis. All the models are available as
+supplementary material, ensuring reproducibility.",2107.00835v1
+2021-07-12,Primitive Rateless Codes,"In this paper, we propose primitive rateless (PR) codes. A PR code is
+characterized by the message length and a primitive polynomial over
+$\mathbf{GF}(2)$, which can generate a potentially limitless number of coded
+symbols. We show that codewords of a PR code truncated at any arbitrary length
+can be represented as subsequences of a maximum-length sequence ($m$-sequence).
+We characterize the Hamming weight distribution of PR codes and their duals and
+show that for a properly chosen primitive polynomial, the Hamming weight
+distribution of the PR code can be well approximated by the truncated binomial
+distribution. We further find a lower bound on the minimum Hamming weight of PR
+codes and show that there always exists a PR code that can meet this bound for
+any desired codeword length. We provide a list of primitive polynomials for
+message lengths up to $40$ and show that the respective PR codes closely meet
+the Gilbert-Varshamov bound at various rates. Simulation results show that PR
+codes can achieve similar block error rates as their BCH counterparts at
+various signal-to-noise ratios (SNRs) and code rates. PR codes are
+rate-compatible and can generate as many coded symbols as required; thus,
+demonstrating a truly rateless performance.",2107.05774v1
+2021-07-16,Linear Programming Bounds for Almost-Balanced Binary Codes,"We revisit the linear programming bounds for the size vs. distance trade-off
+for binary codes, focusing on the bounds for the almost-balanced case, when all
+pairwise distances are between $d$ and $n-d$, where $d$ is the code distance
+and $n$ is the block length. We give an optimal solution to Delsarte's LP for
+the almost-balanced case with large distance $d \geq (n - \sqrt{n})/2 + 1$,
+which shows that the optimal value of the LP coincides with the Grey-Rankin
+bound for self-complementary codes.
+  We also show that a limitation of the asymptotic LP bound shown by
+Samorodnitsky, namely that it is at least the average of the first MRRW upper
+bound and Gilbert-Varshamov bound, continues to hold for the almost-balanced
+case.",2107.07672v1
+2021-07-17,Magnetization switching in the inertial regime,"We have numerically solved the Landau-Lifshitz-Gilbert (LLG) equation in its
+standard and inertial forms to study the magnetization switching dynamics in a
+$3d$ thin film ferromagnet. The dynamics is triggered by ultrashort magnetic
+field pulses of varying width and amplitude in the picosecond and Tesla range.
+We have compared the solutions of the two equations in terms of switching
+characteristic, speed and energy analysis. Both equations return qualitatively
+similar switching dynamics, characterized by regions of slower precessional
+behavior and faster ballistic motion. In case of inertial dynamics, ballistic
+switching is found in a 25 % wider region in the parameter space given by the
+magnetic field amplitude and width. The energy analysis of the dynamics is
+qualitatively different for the standard and inertial LLG equations. In the
+latter case, an extra energy channel, interpreted as the kinetic energy of the
+system, is available. Such extra channel is responsible for a resonant energy
+absorption at THz frequencies, consistent with the occurence of spin nutation.",2107.08234v1
+2021-10-06,Controlled-Phase Gate by Dynamic Coupling of Photons to a Two-Level Emitter,"We propose an architecture for achieving high-fidelity deterministic quantum
+logic gates on dual-rail encoded photonic qubits by letting photons interact
+with a two-level emitter (TLE) inside an optical cavity. The photon wave
+packets that define the qubit are preserved after the interaction due to a
+quantum control process that actively loads and unloads the photons from the
+cavity and dynamically alters their effective coupling to the TLE. The controls
+rely on nonlinear wave mixing between cavity modes enhanced by strong
+externally modulated electromagnetic fields or on AC Stark shifts of the TLE
+transition energy. We numerically investigate the effect of imperfections in
+terms of loss and dephasing of the TLE as well as control field miscalibration.
+Our results suggest that III-V quantum dots in GaAs membranes is a promising
+platform for photonic quantum information processing.",2110.02960v2
+2021-10-12,Magnetization dynamics in the density matrix formalism,"Magnetization dynamics described by the Landau-Lifshitz-Gilbert-Slonczewski
+(LLGS) equation can be formulated to have the form of the well-known
+two-level-system (TLS) equations. Recently, we showed that a DC spin-transfer
+torque (STT) term in the LLGS equation can be mapped to a modulation of the
+carrier relaxation rates in the analogous TLS equations. Here, we extend the
+analogy to the TLS dynamics by including the AC magnetic field, AC
+demagnetization field, and AC STT excitation that we show constitute the
+interaction term in the analogous TLS picture. Interestingly, we find that the
+carrier injection rate in the TLS equations that is responsible for transitions
+between the excited and ground states of the system naturally translates to an
+intense short magnetic pulse that reverses the magnetization state.
+Furthermore, we also show that the two helicities of circularly polarized
+magnetic pulses correspond to the two carrier injection rates in the analogous
+TLS picture. In the context of the highly debated all-optical helicity
+dependent switching experiment, it offers a new explanation of the
+magnetization reversal from first principles.",2110.06138v3
+2021-10-12,Period Ratio Sculpting Near Second-Order Mean-Motion Resonances,"Second-order mean-motion resonances lead to an interesting phenomenon in the
+sculpting of the period ratio distribution due to their shape and width in
+period-ratio/eccentricity space. As the osculating periods librate in
+resonance, the time-averaged period ratio approaches the exact
+commensurability. The width of second-order resonances increases with
+increasing eccentricity, and thus more eccentric systems have a stronger peak
+at commensurability when averaged over sufficient time. The libration period is
+short enough that this time-averaging behavior is expected to appear on the
+timescale of the Kepler mission. Using N-body integrations of simulated planet
+pairs near the 5:3 and 3:1 mean-motion resonances, we investigate the
+eccentricity distribution consistent with the planet pairs observed by Kepler.
+This analysis, an approach independent from previous studies, shows no
+statistically significant peak at the 3:1 resonance and a small peak at the 5:3
+resonance, placing an upper limit on the Rayleigh scale parameter, $\sigma$, of
+the eccentricity of the observed Kepler planets at $\sigma=0.245$ (3:1) and
+$\sigma=0.095$ (5:3) at 95% confidence, consistent with previous results from
+other methods.",2110.06317v1
+2021-10-15,Macroscopic elastic stress and strain produced by irradiation,"Using the notion of eigenstrain produced by the defects formed in a material
+exposed to high energy neutron irradiation, we develop a method for computing
+macroscopic elastic stress and strain arising in components of a fusion power
+plant during operation. In a microstructurally isotropic material, the primary
+cause of macroscopic elastic stress and strain fields is the spatial variation
+of neutron exposure. We show that under traction-free boundary conditions, the
+volume-average elastic stress always vanishes, signifying the formation of a
+spatially heterogeneous stress state, combining compressive and tensile elastic
+deformations at different locations in the same component, and resulting solely
+from the spatial variation of radiation exposure. Several case studies
+pertinent to the design of a fusion power plant are analysed analytically and
+numerically, showing that a spatially varying distribution of defects produces
+significant elastic stresses in ion-irradiated thin films, pressurised
+cylindrical tubes and breeding blanket modules.",2110.07955v1
+2021-10-21,Physics-Based Models for Magneto-Electric Spin-Orbit Logic Circuits,"Spintronic devices are a promising beyond-CMOS device option thanks to their
+energy efficiency and compatibility with CMOS. To accurately capture their
+multi-physics dynamics, a rigorous treatment of both spin and charge and their
+inter-conversion is required. Here we present physics-based device models based
+on 4x4 matrices for the spin-orbit coupling part of the magneto-electric
+spin-orbit (MESO) device. Also, a more rigorous physics model of ferroelectric
+and magnetoelectric switching of ferromagnets, based on Landau-Lifshitz-Gilbert
+(LLG) and Landau-Khalatnikov (LK) equations, is presented. With the combined
+model implemented in a SPICE circuit simulator environment, simulation results
+were obtained which show feasibility of MESO implementation and functional
+operation of buffers, oscillators, and majority gates.",2110.10890v1
+2021-10-29,Thermal melting of discrete time crystals: a dynamical phase transition induced by thermal fluctuations,"The stability of a discrete time crystal against thermal fluctuations has
+been studied numerically by solving a stochastic Landau-Lifshitz-Gilbert
+equation of a periodically-driven classical system composed of interacting
+spins, each of which couples to a thermal bath. It is shown that in the
+thermodynamic limit, even though the long-range temporary crystalline order is
+stable at low temperature, it is melting above a critical temperature, at which
+the system experiences a non-equilibrium phase transition. The critical
+behaviors of the continuous phase transition have been systematically
+investigated, and it is shown that despite the genuine non-equilibrium feature
+of such a periodically driven system, its critical properties fall into the 3D
+Ising universality class with a dynamical exponent ($z=2$) identical to that in
+the critical dynamics of kinetic Ising model without driving.",2110.15506v3
+2021-10-29,Magnetism and Magnetotransport in the Kagome Antiferromagnet $\text{Mn}_3\text{Ge}$,"We perform classical Monte Carlo and stochastic Landau-Lifshitz-Gilbert
+simulations to study temperature dependent magnetism of Kagome antiferromagnet
+(AFM) Weyl metal $\text{Mn}_3\text{Ge}$ and find that a long range chiral order
+sets in at a transition temperature well below the N{\'e}el temperature
+($T_N$). Based on the crystalline symmetries, imposed by the chiral magnetic
+order, we argue for the presence of multiple iso-energetic Weyl nodes (nodes
+that are at same energy and with congruent Fermi surface around them) near
+chemical potential. Using the semi-classical Boltzmann equations, we show that
+the combined contribution to the net longitudinal magnetoconductance (LMC) and
+the planar Hall conductance (PHC) from tilted Weyl nodes can lead to
+signatures, qualitatively distinct from that of a single pair of Weyl nodes. In
+particular, we show that magnetic orders with different chiralities can give
+rise to different periods in LMC and PHC as a function of the in-plane magnetic
+field direction. This is ultimately related to differences in the
+symmetry-imposed constraints on the Weyl nodes.",2110.15864v2
+2021-11-10,Experimental Search for Neutron to Mirror Neutron Oscillations as an Explanation of the Neutron Lifetime Anomaly,"An unexplained $>4\,\sigma$ discrepancy persists between ""beam"" and ""bottle""
+measurements of the neutron lifetime. A new model proposed that conversions of
+neutrons $n$ into mirror neutrons $n'$, part of a dark mirror sector, can
+increase the apparent neutron lifetime by $1\%$ via a small mass splitting
+$\Delta{m}$ between $n$ and $n'$ inside the 4.6 T magnetic field of the
+National Institute of Standards and Technology Beam Lifetime experiment. A
+search for neutron conversions in a 6.6 T magnetic field was performed at the
+Spallation Neutron Source which excludes this explanation for the neutron
+lifetime discrepancy.",2111.05543v2
+2021-11-12,Whirling interlayer fields as a source of stable topological order in moiré CrI3,"The moir\'e engineering of two-dimensional magnets opens unprecedented
+opportunities to design novel magnetic states with promises for spintronic
+device applications. The possibility of stabilizing skyrmions in these
+materials without chiral spin-orbit couplings or dipolar interactions is yet to
+be explored. Here, we investigate the formation and control of ground state
+topological spin textures (TSTs) in moir\'e CrI3 using stochastic
+Landau-Lifshitz-Gilbert simulations. We unveil the emergence of interlayer
+vortex and antivortex Heisenberg exchange fields, stabilizing spontaneous and
+field-assisted ground state TSTs with various topologies. The developed study
+accounts for the full bilayer spin dynamics, thermal fluctuations, and
+intrinsic spin-orbit couplings. By examining the effect of the Kitaev
+interaction and the next nearest-neighbor Dzyaloshinskii-Moriya interaction, we
+propose the latter as the unique spin-orbit coupling mechanism compatible with
+experiments on monolayer and twisted CrI3. Our findings contribute to the
+current knowledge about moir\'e skyrmionics and uncover the nature of
+spin-orbit coupling in CrI3.",2111.06936v2
+2021-11-21,Explicit complex-valued solutions of the 2D eikonal equation,"We present a method to obtain explicit solutions of the complex eikonal
+equation in the plane. This equation arises in the approximation of Helmholtz
+equation by the WKBJ or EWT methods. We obtain the complex-valued solutions
+(called eikonals) as parameterizations in a complex variable. We consider both
+the cases of constant and non-constant index of refraction. In both cases, the
+relevant parameterizations depend on some holomorphic function. In the case of
+non-constant index of refraction, the parametrization also depends on some
+extra exponential complex-valued function and on a quasi-conformal
+homeomorphism. This is due to the use of the theory of pseudo-analytic
+functions and the related similarity principle. The parameterizations give
+information about the formation of caustics and the light and shadow regions
+for the relevant eikonals.",2111.10852v1
+2021-12-08,A comparison of spectral reconstruction methods applied to non-zero temperature NRQCD meson correlation functions,"We present results from the fastsum collaboration's programme to determine
+the spectrum of the bottomonium system as a function of temperature. Three
+different methods of extracting spectral information are discussed: a Maximum
+Likelihood approach using a Gaussian spectral function for the ground state,
+the Backus Gilbert method, and the Kernel Ridge Regression machine learning
+procedure. We employ the fastsum anisotropic lattices with 2+1 dynamical quark
+flavours, with temperatures ranging from 47 to 375 MeV.",2112.04201v1
+2021-12-23,Nutation spin waves in ferromagnets,"Magnetization dynamics and spin waves in ferromagnets are investigated using
+the inertial Landau-Lifshitz-Gilbert equation. Taking inertial magnetization
+dynamics into account, dispersion relations describing the propagation of
+nutation spin waves in an arbitrary direction relative to the applied magnetic
+field are derived via Maxwell's equations. It is found that the inertia of
+magnetization causes the hybridization of electromagnetic waves and nutation
+spin waves in ferromagnets, hybrid nutation spin waves emerge, and the redshift
+of frequencies of precession spin waves is initiated, which transforms to
+precession-nutation spin waves. These effects depend sharply on the direction
+of wave propagation relative to the applied magnetic field. Moreover, the waves
+propagating parallel to the applied field are circularly polarized, while the
+waves propagating perpendicular to that field are elliptically polarized. The
+characteristics of these spin nutation waves are also analyzed.",2112.12503v3
+2021-12-30,Spin Torque Oscillations Triggered by In-plane Field,"We study the dynamics of a spin torque nano oscillator that consists of
+parallelly magnetized free and pinned layers by numerically solving the
+associated Landau-Lifshitz-Gilbert-Slonczewski equation in the presence of a
+field-like torque. We observe that an in-plane magnetic field which is applied
+for a short interval of time ($<$1ns) triggers the magnetization to exhibit
+self-oscillations from low energy initial magnetization state. Also, we confirm
+that the frequency of oscillations can be tuned over the range $\sim$25 GHz to
+$\sim$72 GHz by current, even in the absence of field-like torque. We find the
+frequency enhancement up to 10 GHz by the presence of field-like torque. We
+determine the Q-factor for different frequencies and show that it increases
+with frequency. Our analysis with thermal noise confirms that the system is
+stable against thermal noise and the dynamics is not altered appreciably by it.",2112.15004v1
+2022-01-11,Ultrahigh quality infrared polaritonic resonators based on bottom-up-synthesized van der Waals nanoribbons,"van der Waals nanomaterials supporting phonon polariton quasiparticles
+possess unprecedented light confinement capabilities, making them ideal systems
+for molecular sensing, thermal emission, and subwavelength imaging
+applications, but they require defect-free crystallinity and nanostructured
+form factors to fully showcase these capabilities. We introduce
+bottom-up-synthesized {\alpha}-MoO3 structures as nanoscale phonon polaritonic
+systems that feature tailorable morphologies and crystal qualities consistent
+with bulk single crystals. {\alpha}-MoO3 nanoribbons serve as low-loss
+hyperbolic Fabry-P\'erot nanoresonators, and we experimentally map hyperbolic
+resonances over four Reststrahlen bands spanning the far- and mid-infrared
+spectral range, including resonance modes beyond the tenth order. The measured
+quality factors are the highest from phonon polaritonic van der Waals
+structures to date. We anticipate that bottom-up-synthesized polaritonic van
+der Waals nanostructures will serve as an enabling high-performance and
+low-loss platform for infrared optical and optoelectronic applications.",2201.03748v1
+2022-01-12,The angular dependence of magnetization dynamics induced by a GHz range strain pulse,"The dynamics of magnetization is important in spintronics, where the coupling
+between phonon and magnon attracts much attention. In this work, we study the
+angular dependence of the coupling between longitudinal-wave phonon and magnon.
+We investigated the magnetization dynamics using the time-resolved
+magneto-optical Kerr effect, which allows measuring spin-wave resonances and
+the magnetic echo signal. The frequency, mode number, and amplitude of the
+spin-wave resonance change with the out-of-plane angle of the external magnetic
+field. The amplitude of the magnetic echo signal caused by the strain pulse
+also changes with the angle. We calculate these angular dependences based on
+the Landau-Lifshitz-Gilbert equation and find that the angles of the external
+field and magnetic moment are important factors for the phonon-magnon coupling
+when phonon propagates in the thickness direction under the out-of-plane
+magnetic field.",2201.04396v1
+2022-01-17,A Theory of Second-Order Wireless Network Optimization and Its Application on AoI,"This paper introduces a new theoretical framework for optimizing second-order
+behaviors of wireless networks. Unlike existing techniques for network utility
+maximization, which only considers first-order statistics, this framework
+models every random process by its mean and temporal variance. The inclusion of
+temporal variance makes this framework well-suited for modeling stateful fading
+wireless channels and emerging network performance metrics such as
+age-of-information (AoI). Using this framework, we sharply characterize the
+second-order capacity region of wireless access networks. We also propose a
+simple scheduling policy and prove that it can achieve every interior point in
+the second-order capacity region. To demonstrate the utility of this framework,
+we apply it for an important open problem: the optimization of AoI over
+Gilbert-Elliott channels. We show that this framework provides a very accurate
+characterization of AoI. Moreover, it leads to a tractable scheduling policy
+that outperforms other existing work.",2201.06486v1
+2022-01-18,Self-Modifying Code in Open-Ended Evolutionary Systems,"Having a model and being able to implement open-ended evolutionary systems is
+important for advancing our understanding of open-endedness. Complex systems
+science and newest generation high-level programming languages provide
+intriguing possibilities to do so. First, some recent advances in modelling and
+implementing open-ended evolutionary systems are reviewed. Then, the so-called
+allagmatic method is introduced that describes, models, implements, and allows
+interpretation of complex systems. After highlighting some current modelling
+and implementation challenges, model building blocks of open-ended evolutionary
+systems are identified, a system metamodel of open-ended evolution is
+formalised in the allagmatic method, an implementation self-modifying code
+prototype with a high-level programming language is provided, and guidance from
+the allagmatic method to create code blocks is described. The proposed
+prototype allows modifying code at runtime in a controlled way within a system
+metamodel. Since the allagmatic method has been built based on metaphysical
+concepts borrowed from Gilbert Simondon and Alfred N. Whitehead, the proposed
+prototype provides a promising starting point to interpret novelty generated at
+runtime with the help of a metaphysical framework.",2201.06858v2
+2022-01-28,Piezo-optomechanical cantilever modulators for VLSI visible photonics,"Visible-wavelength very large-scale integration (VLSI) photonic circuits have
+potential to play important roles in quantum information and sensing
+technologies. The realization of scalable, high-speed, and low-loss photonic
+mesh circuits depends on reliable and well-engineered visible photonic
+components. Here we report a low-voltage optical phase shifter based on
+piezo-actuated mechanical cantilevers, fabricated on a CMOS compatible, 200 mm
+wafer-based visible photonics platform. We show linear phase and amplitude
+modulation with 6 V$_{\pi}$-cm in differential operation, -1.5 dB to -2 dB
+insertion loss, and up to 40 dB contrast in the 700 nm - 780 nm range. By
+adjusting selected cantilever parameters, we demonstrate a low-displacement and
+a high-displacement device, both exhibiting a nearly flat frequency response
+from DC to a peak mechanical resonance at 23 MHz and 6.8 MHz respectively,
+which through resonant enhancement of Q~40, further decreases the operating
+voltage down to 0.15 V$_{\pi}$-cm.",2201.12447v1
+2022-01-30,"Spintronics-compatible approach to solving maximum satisfiability problems with probabilistic computing, invertible logic and parallel tempering","The search of hardware-compatible strategies for solving NP-hard
+combinatorial optimization problems (COPs) is an important challenge of today s
+computing research because of their wide range of applications in real world
+optimization problems. Here, we introduce an unconventional scalable approach
+to face maximum satisfiability problems (Max-SAT) which combines probabilistic
+computing with p-bits, parallel tempering, and the concept of invertible logic
+gates. We theoretically show the spintronic implementation of this approach
+based on a coupled set of Landau-Lifshitz-Gilbert equations, showing a
+potential path for energy efficient and very fast (p-bits exhibiting ns time
+scale switching) architecture for the solution of COPs. The algorithm is
+benchmarked with hard Max-SAT instances from the 2016 Max-SAT competition
+(e.g., HG-4SAT-V150-C1350-1.cnf which can be described with 2851 p-bits),
+including weighted Max-SAT and Max-Cut problems.",2201.12858v1
+2022-02-01,Numerical Model Of Harmonic Hall Voltage Detection For Spintronic Devices,"We present a numerical macrospin model for harmonic voltage detection in
+multilayer spintronic devices. The core of the computational backend is based
+on the Landau-Lifshitz-Gilbert-Slonczewski equation, which combines high
+performance with satisfactory, for large-scale applications, agreement with the
+experimental results. We compare the simulations with the experimental findings
+in Ta/CoFeB bilayer system for angular- and magnetic field-dependent resistance
+measurements, electrically detected magnetisation dynamics, and harmonic Hall
+voltage detection. Using simulated scans of the selected system parameters such
+as the polar angle $\theta$, magnetisation saturation
+($\mu_\textrm{0}M_\textrm{s}$) or uniaxial magnetic anisotropy ($K_\textrm{u}$)
+we show the resultant changes in the harmonic Hall voltage, demonstrating the
+dominating influence of the $\mu_\textrm{0}M_\textrm{s}$ on the first and
+second harmonics. In the spin-diode ferromagnetic resonance (SD-FMR) technique
+resonance method the ($\mu_\textrm{0}M_\textrm{s}$, $K_\textrm{u}$) parameter
+space may be optimised numerically to obtain a set of viable curves that fit
+the experimental data.",2202.00364v1
+2022-02-03,Magnetic domain wall dynamics under external electric field in bilayer CrI$_3$,"Motivated by manipulating the magnetic order of bilayer CrI$_3$, we carry out
+microscopic calculations to find the magnetic order and various magnetic
+domains of the system in the presence of an electric field. Making use of
+density functional simulations, a spin model Hamiltonian is introduced
+consisting of isotropic exchange couplings, Dzyaloshinskii-Moriya (DM)
+interaction, and on-site magnetic anisotropy. The spin dynamics of two
+well-known states of bilayer CrI$_3$, low temperature (LT) and high temperature
+(HT) phases, are obtained by solving the Landau-Lifshitz-Gilbert equation. We
+show that the magnetic texture is stacking-dependent in bilayer CrI$_3$ and
+stable magnetic domains can appear in the HT stack which are tunable by
+external electric and magnetic fields. Therefore, we suggest that the HT phase
+represents a promising candidate for data storage in the modern generation of
+spintronic devices working on magnetic domain engineering.",2202.01394v2
+2022-02-07,Spin-transfer-assisted parametric pumping of magnons in yttrium iron garnet,"The combination of parametric pumping and spin-transfer torque is a powerful
+approach that enables high-level control over magnetic excitations in thin-film
+ferromagnets. The excitation parameters, such as pumping power and external
+field strength, affect the instabilities of individual magnon modes. We
+theoretically explore how the simultaneous effects of parametric pumping and
+spin transfer torque influence these magnetic instabilities in a thin-film
+ferromagnet. Within the Landau-Lifshitz-Gilbert framework, we perform
+micromagnetic simulations of magnon excitations in yttrium iron garnet by
+pumping, spin transfer torque, and a combination of the two. We find that
+consistent with experimental results, the magnitude and direction of the
+spin-transfer torque tune the parametric instability thresholds.",2202.03247v2
+2022-02-13,Critical-layer instability of shallow water magnetohydrodynamic shear flows,"In this paper, the instability of shallow water shear flow with a sheared
+parallel magnetic field is studied. Waves propagating in such magnetic shear
+flows encounter critical levels where the phase velocity relative to the basic
+flow $c-U(y)$ matches the Alfv\'en wave velocities $\pm B(y)/\sqrt{\mu\rho}$,
+based on the local magnetic field $B(y)$, the magnetic permeability $\mu$ and
+the mass density of the fluid $\rho$. It is shown that when the two critical
+levels are close to each other, the critical layer can generate an instability.
+The instability problem is solved, combining asymptotic solutions at large
+wavenumbers and numerical solutions, and the mechanism of instability explained
+using the conservation of momentum. For the shallow water MHD system, the paper
+gives the general form of the local differential equation governing such
+coalescing critical layers for any generic field and flow profiles, and
+determines precisely how the magnetic field modifies the purely hydrodynamic
+stability criterion based on the potential vorticity gradient in the critical
+layer. The curvature of the magnetic field profile, or equivalently the
+electric current gradient, $J' = - B''/\mu$ in the critical layer is found to
+play a complementary role in the instability.",2202.06272v1
+2022-02-21,On Grid Codes,"Versions of the Hamming and Gilbert-Varshamov bounds for codes in
+$\prod_{i=1}^{n}[0,m_{i}-1]$ with respect to the Manhattan distance are
+presented. Given an abelian group $G$ isomorphic to $C_{m_{1}}\times \cdots
+\times C_{m_{n}}$, the Hamming, Manhattan, and Lee distances are defined in
+$G$; a formula for the minimum Hamming distance of codes that are cyclic
+subgroups of $G$ is provided, and some lower bounds for the minimum Manhattan
+distance of these codes are determined in terms of their minimum Hamming and
+Lee distances. Examples illustrating the main results and an application of
+these are provided.",2202.10005v4
+2022-02-23,Convergence of Oja's online principal component flow,"Online principal component analysis (PCA) has been an efficient tool in
+practice to reduce dimension. However, convergence properties of the
+corresponding ODE are still unknown, including global convergence, stable
+manifolds, and convergence rate. In this paper, we focus on the stochastic
+gradient ascent (SGA) method proposed by Oja. By regarding the corresponding
+ODE as a Landau-Lifshitz-Gilbert (LLG) equation on the Stiefel manifold, we
+proved global convergence of the ODE. Moreover, we developed a new technique to
+determine stable manifolds. This technique analyzes the rank of the initial
+datum. Using this technique, we derived the explicit expression of the stable
+manifolds. As a consequence, exponential convergence to stable equilibrium
+points was also proved. The success of this new technique should be attributed
+to the semi-decoupling property of the SGA method: iteration of previous
+components does not depend on that of later ones. As far as we know, our result
+is the first complete one on the convergence of an online PCA flow, providing
+global convergence, explicit characterization of stable manifolds, and closed
+formula of exponential convergence depending on the spectrum gap.",2202.11308v1
+2022-02-28,Curb Your Self-Modifying Code,"Self-modifying code has many intriguing applications in a broad range of
+fields including software security, artificial general intelligence, and
+open-ended evolution. Having control over self-modifying code, however, is
+still an open challenge since it is a balancing act between providing as much
+freedom as possible so as not to limit possible solutions, while at the same
+time imposing restriction to avoid security issues and invalid code or
+solutions. In the present study, I provide a prototype implementation of how
+one might curb self-modifying code by introducing control mechanisms for code
+modifications within specific regions and for specific transitions between code
+and data. I show that this is possible to achieve with the so-called allagmatic
+method - a framework to formalise, model, implement, and interpret complex
+systems inspired by Gilbert Simondon's philosophy of individuation and Alfred
+North Whitehead's philosophy of organism. Thereby, the allagmatic method serves
+as guidance for self-modification based on concepts defined in a metaphysical
+framework. I conclude that the allagmatic method seems to be a suitable
+framework for control mechanisms in self-modifying code and that there are
+intriguing analogies between the presented control mechanisms and gene
+regulation.",2202.13830v2
+2022-03-03,A general adaptive framework for multivariate point null testing,"As a common step in refining their scientific inquiry, investigators are
+often interested in performing some screening of a collection of given
+statistical hypotheses. For example, they may wish to determine whether any one
+of several patient characteristics are associated with a health outcome of
+interest. Existing generic methods for testing a multivariate hypothesis --
+such as multiplicity corrections applied to individual hypothesis tests -- can
+easily be applied across a variety of problems but can suffer from low power in
+some settings. Tailor-made procedures can attain higher power by building
+around problem-specific information but typically cannot be easily adapted to
+novel settings. In this work, we propose a general framework for testing a
+multivariate point null hypothesis in which the test statistic is adaptively
+selected to provide increased power. We present theoretical large-sample
+guarantees for our test under both fixed and local alternatives. In simulation
+studies, we show that tests created using our framework can perform as well as
+tailor-made methods when the latter are available, and we illustrate how our
+procedure can be used to create tests in two settings in which tailor-made
+methods are not currently available.",2203.01897v1
+2022-03-09,KPE: Keypoint Pose Encoding for Transformer-based Image Generation,"Transformers have recently been shown to generate high quality images from
+text input. However, the existing method of pose conditioning using skeleton
+image tokens is computationally inefficient and generate low quality images.
+Therefore we propose a new method; Keypoint Pose Encoding (KPE); KPE is 10
+times more memory efficient and over 73% faster at generating high quality
+images from text input conditioned on the pose. The pose constraint improves
+the image quality and reduces errors on body extremities such as arms and legs.
+The additional benefits include invariance to changes in the target image
+domain and image resolution, making it easily scalable to higher resolution
+images. We demonstrate the versatility of KPE by generating photorealistic
+multiperson images derived from the DeepFashion dataset. We also introduce a
+evaluation method People Count Error (PCE) that is effective in detecting error
+in generated human images.",2203.04907v2
+2022-03-10,StyleBabel: Artistic Style Tagging and Captioning,"We present StyleBabel, a unique open access dataset of natural language
+captions and free-form tags describing the artistic style of over 135K digital
+artworks, collected via a novel participatory method from experts studying at
+specialist art and design schools. StyleBabel was collected via an iterative
+method, inspired by `Grounded Theory': a qualitative approach that enables
+annotation while co-evolving a shared language for fine-grained artistic style
+attribute description. We demonstrate several downstream tasks for StyleBabel,
+adapting the recent ALADIN architecture for fine-grained style similarity, to
+train cross-modal embeddings for: 1) free-form tag generation; 2) natural
+language description of artistic style; 3) fine-grained text search of style.
+To do so, we extend ALADIN with recent advances in Visual Transformer (ViT) and
+cross-modal representation learning, achieving a state of the art accuracy in
+fine-grained style retrieval.",2203.05321v2
+2022-03-12,The mass-lumped midpoint scheme for computational micromagnetics: Newton linearization and application to magnetic skyrmion dynamics,"We discuss a mass-lumped midpoint scheme for the numerical approximation of
+the Landau-Lifshitz-Gilbert equation, which models the dynamics of the
+magnetization in ferromagnetic materials. In addition to the classical
+micromagnetic field contributions, our setting covers the non-standard
+Dzyaloshinskii-Moriya interaction, which is the essential ingredient for the
+enucleation and stabilization of magnetic skyrmions. Our analysis also includes
+the inexact solution of the arising nonlinear systems, for which we discuss
+both a constraint preserving fixed-point solver from the literature and a novel
+approach based on the Newton method. We numerically compare the two
+linearization techniques and show that the Newton solver leads to a
+considerably lower number of nonlinear iterations. Moreover, in a numerical
+study on magnetic skyrmions, we demonstrate that, for magnetization dynamics
+that are very sensitive to energy perturbations, the midpoint scheme, due to
+its conservation properties, is superior to the dissipative tangent plane
+schemes from the literature.",2203.06445v1
+2022-03-16,The Geometry and Topology of Stationary Multi-Axisymmetric Vacuum Black Holes in Higher Dimensions,"Extending recent work in 5 dimensions, we prove the existence and uniqueness
+of solutions to the reduced Einstein equations for vacuum black holes in
+$(n+3)$-dimensional spacetimes admitting the isometry group $\mathbb{R}\times
+U(1)^{n}$, with Kaluza-Klein asymptotics for $n\geq3$. This is equivalent to
+establishing existence and uniqueness for singular harmonic maps $\varphi:
+\mathbb{R}^3\setminus\Gamma\rightarrow SL(n+1,\mathbb{R})/SO(n+1)$ with
+prescribed blow-up along $\Gamma$, a subset of the $z$-axis in $\mathbb{R}^3$.
+We also analyze the topology of the domain of outer communication for these
+spacetimes, by developing an appropriate generalization of the plumbing
+construction used in the lower dimensional case. Furthermore, we provide a
+counterexample to a conjecture of Hollands-Ishibashi concerning the topological
+classification of the domain of outer communication. A refined version of the
+conjecture is then presented and established in spacetime dimensions less than
+8.",2203.08325v1
+2022-03-18,Smectite phase separation is driven by emergent interfacial dynamics,"Smectite clay minerals have an outsize impact on the response of clay-rich
+media to common stimuli, such as water imbibition and ion exchange, motivating
+extensive effort to understand microscopic behaviors resulting from these
+processes such as swelling and exfoliation. Nonetheless, there is no general
+consensus about the microscopic forces that govern smectite properties, which
+are model systems for understanding colloidal and interfacial phenomena more
+generally. We find that the complex free energy surface arising from the
+interplay of at least four intermolecular forces and their nonlinear couplings
+that control local particle-particle interactions leads to dynamic, unstable
+equilibria between distinct phases. Mechanical disequilibrium arising from
+osmotic gradients between curved or interacting interfaces drive the dynamic
+exchange of layers and ions between dense and dilute phases via avalanche
+transitions that are sustained by thermal fluctuations. We suggest that the
+surprising interfacial dynamics displayed by smectite minerals, arising from
+the vastly different mobilities of water, ions and mineral, makes them
+fundamentally distinct from non-clay minerals because their structures are
+easily perturbed away from simultaneous chemical and mechanical equilibrium.",2203.10129v1
+2022-03-27,Low power In Memory Computation with Reciprocal Ferromagnet/Topological Insulator Heterostructures,"The surface state of a 3D topological insulator (3DTI) is a spin-momentum
+locked conductive state, whose large spin hall angle can be used for the
+energy-efficient spin orbit torque based switching of an overlying ferromagnet
+(FM). Conversely, the gated switching of the magnetization of a separate FM in
+or out of the TI surface plane, can turn on and off the TI surface current. The
+gate tunability of the TI Dirac cone gap helps reduce its sub-threshold swing.
+By exploiting this reciprocal behaviour, we can use two FM/3DTI
+heterostructures to design a 1-Transistor 1-magnetic tunnel junction random
+access memory unit (1T1MTJ RAM) for an ultra low power Processing-in-Memory
+(PiM) architecture. Our calculation involves combining the Fokker-Planck
+equation with the Non-equilibrium Green Function (NEGF) based flow of
+conduction electrons and Landau-Lifshitz-Gilbert (LLG) based dynamics of
+magnetization. Our combined approach allows us to connect device performance
+metrics with underlying material parameters, which can guide proposed
+experimental and fabrication efforts.",2203.14389v3
+2022-03-17,Symmetry effects on the static and dynamic properties of coupled magnetic oscillators,"The effect of symmetry on the resonance spectra of antiferromagnetically
+coupled oscillators has attracted new interest with the discovery of
+symmetry-breaking induced anti-crossings. Here, we experimentally characterise
+the resonance spectrum of a synthetic antiferromagnet Pt/CoFeB/Ru/CoFeB/Pt,
+where we are able to independently tune the effective magnetisation of the two
+coupled magnets. To model our results we apply the mathematical methods of
+group theory to the solutions of the Landau Lifshitz Gilbert equation. This
+general approach, usually applied to quantum mechanical systems, allows us to
+identify the main features of the resonance spectrum in terms of symmetry
+breaking and to make a direct comparison with crystal antiferromagnets.",2204.01490v1
+2022-04-17,Gravitational Solitons and Complete Ricci Flat Riemannian Manifolds of Infinite Topological Type,"We present several new space-periodic solutions of the static vacuum Einstein
+equations in higher dimensions, both with and without black holes, having
+Kasner asymptotics. These latter solutions are referred to as gravitational
+solitons. Further partially compactified solutions are also obtained by taking
+appropriate quotients, and the topologies are computed explicitly in terms of
+connected sums of products of spheres. In addition, it is shown that there is a
+correspondence, via Wick rotation, between the spacelike slices of the solitons
+and black hole solutions in one dimension less. As a corollary, the solitons
+give rise to complete Ricci flat Riemannian manifolds of infinite topological
+type and generic holonomy, in dimensions 4 and higher.",2204.08048v2
+2022-04-26,Cosmology from the kinetic polarized Sunyaev Zel'dovich effect,"The cosmic microwave background (CMB) photons that scatter off free electrons
+in the large-scale structure induce a linear polarization pattern proportional
+to the remote CMB temperature quadrupole observed in the electrons' rest frame.
+The associated blackbody polarization anisotropies are known as the polarized
+Sunyaev Zel'dovich (pSZ) effect. Relativistic corrections to the remote
+quadrupole field give rise to a non-blackbody polarization anisotropy
+proportional to the square of the transverse peculiar velocity field; this is
+the kinetic polarized Sunyaev Zel'dovich (kpSZ) effect. In this paper, we
+forecast the ability of future CMB and galaxy surveys to detect the kpSZ
+effect, finding that a statistically significant detection is within the reach
+of planned experiments. We further introduce a quadratic estimator for the
+square of the peculiar velocity field based on a galaxy survey and CMB
+polarization. Finally, we outline how the kpSZ effect is a probe of cosmic
+birefringence and primordial non-Gaussianity, forecasting the reach of future
+experiments.",2204.12503v2
+2022-04-27,Advantages of maintaining a multi-task project-specific bot: an experience report,"Bots are becoming a popular method for automating basic everyday tasks in
+many software projects. This is true in particular because of the availability
+of many off-the-shelf task-specific bots that teams can quickly adopt (which
+are sometimes completed with additional task-specific custom bots). Based on
+our experience in the Coq project, where we have developed and maintained a
+multi-task project-specific bot, we argue that this alternative approach to
+project automation should receive more attention because it strikes a good
+balance between productivity and adaptibility. In this article, we describe the
+kind of automation that our bot implements, what advantages we have gained by
+maintaining a project-specific bot, and the technology and architecture choices
+that have made it possible. We draw conclusions that should generalize to other
+medium-sized software teams willing to invest in project automation without
+disrupting their workflows.",2204.12758v1
+2022-04-29,Self-consistent solution of magnetic and friction energy losses of a magnetic nanoparticle,"We present a simple simulation model for analysing magnetic and frictional
+losses of magnetic nano-particles in viscous fluids subject to alternating
+magnetic fields. Assuming a particle size below the single-domain limit, we use
+a macrospin approach and solve the Landau-Lifshitz-Gilbert equation coupled to
+the mechanical torque equation. Despite its simplicity the presented model
+exhibits surprisingly rich physics and enables a detailed analysis of the
+different loss processes depending on field parameters and initial arrangement
+of the particle and the field. Depending on those parameters regions of
+different steady states emerge: a region with dominating N\'eel relaxation and
+high magnetic losses and another region region with high frictional losses at
+low fields or low frequencies. The energy increases continuously even across
+regime boundaries up to frequencies above the Brownian relaxation limit. At
+those higher frequencies the steady state can also depend on the initial
+orientation of the particle in the external field. The general behavior and
+special cases and their specific absorption rates are compared and discussed.",2204.14106v3
+2022-05-10,Programming Data Structures for Large-Scale Desktop Simulations of Complex Systems,"The investigation of complex systems requires running large-scale simulations
+over many temporal iterations. It is therefore important to provide efficient
+implementations. The present study borrows philosophical concepts from Gilbert
+Simondon to identify data structures and algorithms that have the biggest
+impact on running time and memory usage. These are the entity $e$-tuple
+$\mathcal{E}$ and the intertwined update function $\phi$. Focusing on
+implementing data structures in C#, $\mathcal{E}$ is implemented as a list of
+objects according to current software engineering practice and as an array of
+pointers according to theoretical considerations. Cellular automaton
+simulations with $10^9$ entities over one iteration reveal that the object-list
+with dynamic typing and multi-state readiness has a drastic effect on running
+time and memory usage, especially dynamic typing as it has a big impact on the
+evolution time. Pointer-arrays are possible to implement in C# and are more
+running time and memory efficient as compared to the object-list
+implementation, however, they are cumbersome to implement. In conclusion,
+avoiding dynamic typing in object-list based implementations or using
+pointer-arrays gives evolution times that are acceptable in practice, even on
+desktop computers.",2205.04837v2
+2022-05-10,Sensible AI: Re-imagining Interpretability and Explainability using Sensemaking Theory,"Understanding how ML models work is a prerequisite for responsibly designing,
+deploying, and using ML-based systems. With interpretability approaches, ML can
+now offer explanations for its outputs to aid human understanding. Though these
+approaches rely on guidelines for how humans explain things to each other, they
+ultimately solve for improving the artifact -- an explanation. In this paper,
+we propose an alternate framework for interpretability grounded in Weick's
+sensemaking theory, which focuses on who the explanation is intended for.
+Recent work has advocated for the importance of understanding stakeholders'
+needs -- we build on this by providing concrete properties (e.g., identity,
+social context, environmental cues, etc.) that shape human understanding. We
+use an application of sensemaking in organizations as a template for discussing
+design guidelines for Sensible AI, AI that factors in the nuances of human
+cognition when trying to explain itself.",2205.05057v1
+2022-05-14,SaiNet: Stereo aware inpainting behind objects with generative networks,"In this work, we present an end-to-end network for stereo-consistent image
+inpainting with the objective of inpainting large missing regions behind
+objects. The proposed model consists of an edge-guided UNet-like network using
+Partial Convolutions. We enforce multi-view stereo consistency by introducing a
+disparity loss. More importantly, we develop a training scheme where the model
+is learned from realistic stereo masks representing object occlusions, instead
+of the more common random masks. The technique is trained in a supervised way.
+Our evaluation shows competitive results compared to previous state-of-the-art
+techniques.",2205.07014v1
+2022-05-15,Sociotechnical Specification for the Broader Impacts of Autonomous Vehicles,"Autonomous Vehicles (AVs) will have a transformative impact on society.
+Beyond the local safety and efficiency of individual vehicles, these effects
+will also change how people interact with the entire transportation system.
+This will generate a diverse range of large and foreseeable effects on social
+outcomes, as well as how those outcomes are distributed. However, the ability
+to control both the individual behavior of AVs and the overall flow of traffic
+also provides new affordances that permit AVs to control these effects. This
+comprises a problem of sociotechnical specification: the need to distinguish
+which essential features of the transportation system are in or out of scope
+for AV development. We present this problem space in terms of technical,
+sociotechnical, and social problems, and illustrate examples of each for the
+transport system components of social mobility, public infrastructure, and
+environmental impacts. The resulting research methodology sketches a path for
+developers to incorporate and evaluate more transportation system features
+within AV system components over time.",2205.07395v1
+2022-05-19,Collision Detection Accelerated: An Optimization Perspective,"Collision detection between two convex shapes is an essential feature of any
+physics engine or robot motion planner. It has often been tackled as a
+computational geometry problem, with the Gilbert, Johnson and Keerthi (GJK)
+algorithm being the most common approach today. In this work we leverage the
+fact that collision detection is fundamentally a convex optimization problem.
+In particular, we establish that the GJK algorithm is a specific sub-case of
+the well-established Frank-Wolfe (FW) algorithm in convex optimization. We
+introduce a new collision detection algorithm by adapting recent works linking
+Nesterov acceleration and Frank-Wolfe methods. We benchmark the proposed
+accelerated collision detection method on two datasets composed of strictly
+convex and non-strictly convex shapes. Our results show that our approach
+significantly reduces the number of iterations to solve collision detection
+problems compared to the state-of-the-art GJK algorithm, leading to up to two
+times faster computation times.",2205.09663v2
+2022-05-31,"Solutions of the matrix equation $p(X)=A$, with polynomial function $p(λ)$ over field extensions of $\mathbb{Q}$","Let $\mathbb{H}$ be a field with
+$\mathbb{Q}\subset\mathbb{H}\subset\mathbb{C}$, and let $p(\lambda)$ be a
+polynomial in $\mathbb{H}[\lambda]$, and let $A\in\mathbb{H}^{n\times n}$ be
+nonderogatory. In this paper we consider the problem of finding a solution
+$X\in\mathbb{H}^{n\times n}$ to $p(X)=A$. A necessary condition for this to be
+possible is already known from a paper by M.P. Drazin. Under an additional
+condition we provide an explicit construction of such solutions. The
+similarities and differences with the derogatory case will be discussed as
+well.
+  One of the tools needed in the paper is a new canonical form, which may be of
+independent interest. It combines elements of the rational canonical form with
+elements of the Jordan canonical form.",2205.15682v1
+2022-06-02,A Fast Randomized Algorithm for Computing an Approximate Null Space,"Randomized algorithms in numerical linear algebra can be fast, scalable and
+robust. This paper examines the effect of sketching on the right singular
+vectors corresponding to the smallest singular values of a tall-skinny matrix.
+We analyze a fast algorithm by Gilbert, Park and Wakin for finding the trailing
+right singular vectors using randomization by examining the quality of the
+solution using multiplicative perturbation theory. For an $m\times n$ ($m\geq
+n$) matrix, the algorithm runs with complexity $O(mn\log n +n^3)$ which is
+faster than the standard $O(mn^2)$ methods. In applications, numerical
+experiments show great speedups including a $30\times$ speedup for the AAA
+algorithm and $10\times$ speedup for the total least squares problem.",2206.00975v3
+2022-06-10,Differentiable Rendering of Neural SDFs through Reparameterization,"We present a method to automatically compute correct gradients with respect
+to geometric scene parameters in neural SDF renderers. Recent physically-based
+differentiable rendering techniques for meshes have used edge-sampling to
+handle discontinuities, particularly at object silhouettes, but SDFs do not
+have a simple parametric form amenable to sampling. Instead, our approach
+builds on area-sampling techniques and develops a continuous warping function
+for SDFs to account for these discontinuities. Our method leverages the
+distance to surface encoded in an SDF and uses quadrature on sphere tracer
+points to compute this warping function. We further show that this can be done
+by subsampling the points to make the method tractable for neural SDFs. Our
+differentiable renderer can be used to optimize neural shapes from multi-view
+images and produces comparable 3D reconstructions to recent SDF-based inverse
+rendering methods, without the need for 2D segmentation masks to guide the
+geometry optimization and no volumetric approximations to the geometry.",2206.05344v1
+2022-06-15,Cautious Learning of Multiattribute Preferences,"This paper is dedicated to a cautious learning methodology for predicting
+preferences between alternatives characterized by binary attributes (formally,
+each alternative is seen as a subset of attributes). By ""cautious"", we mean
+that the model learned to represent the multi-attribute preferences is general
+enough to be compatible with any strict weak order on the alternatives, and
+that we allow ourselves not to predict some preferences if the data collected
+are not compatible with a reliable prediction. A predicted preference will be
+considered reliable if all the simplest models (following Occam's razor
+principle) explaining the training data agree on it. Predictions are based on
+an ordinal dominance relation between alternatives [Fishburn and LaValle,
+1996]. The dominance relation relies on an uncertainty set encompassing the
+possible values of the parameters of the multi-attribute utility function.
+Numerical tests are provided to evaluate the richness and the reliability of
+the predictions made.",2206.07341v1
+2022-06-23,Probabilistic load forecasting for the low voltage network: forecast fusion and daily peaks,"Short-term forecasts of energy consumption are invaluable for the operation
+of energy systems, including low voltage electricity networks. However, network
+loads are challenging to predict when highly desegregated to small numbers of
+customers, which may be dominated by individual behaviours rather than the
+smooth profiles associated with aggregate consumption. Furthermore,
+distribution networks are challenged almost entirely by peak loads, and tasks
+such as scheduling storage and/or demand flexibility maybe be driven by
+predicted peak demand, a feature that is often poorly characterised by
+general-purpose forecasting methods. Here we propose an approach to predict the
+timing and level of daily peak demand, and a data fusion procedure for
+combining conventional and peak forecasts to produce a general-purpose
+probabilistic forecast with improved performance during peaks. The proposed
+approach is demonstrated using real smart meter data and a hypothetical low
+voltage network hierarchy comprising feeders, secondary and primary
+substations. Fusing state-of-the-art probabilistic load forecasts with peak
+forecasts is found to improve performance overall, particularly at smart-meter
+and feeder levels and during peak hours, where improvement in terms of CRPS
+exceeds 10%.",2206.11745v2
+2022-06-26,Impact of Channel Memory on the Data Freshness,"In this letter, we investigate the impact of channel memory on the average
+age of information (AoI) for networks with various packet arrival models under
+first-come-first-served (FCFS) and preemptive last-generated-first-served
+(pLGFS) policies over Gilbert-Elliott (GE) erasure channel. For networks with
+Bernoulli arrival model, we first derive the average AoI under the pLGFS
+queuing policy, and then characterize the AoI gap between the FCFS and pLGFS
+policies. For networks with Bernoulli arrival and generate-at-will arrival
+models, the AoI performances under the FCFS and pLGFS policies are derived
+explicitly. For networks with periodic arrival model, we derive the closed-form
+expression for the average AoI under pLGFS over a general GE channel and
+propose a numerical algorithm for calculating that under FCFS efficiently. It
+is revealed that for pLGFS policy, the average AoI increases monotonically with
+channel memory $\eta$ at $\frac{\eta}{1-\eta}$ over the symmetric GE channel.
+For FCFS, the average AoI increases even faster due to the queuing delay, with
+an additional term related to the packet arrival rate.",2206.12797v3
+2022-07-06,Light-weight spatio-temporal graphs for segmentation and ejection fraction prediction in cardiac ultrasound,"Accurate and consistent predictions of echocardiography parameters are
+important for cardiovascular diagnosis and treatment. In particular,
+segmentations of the left ventricle can be used to derive ventricular volume,
+ejection fraction (EF) and other relevant measurements. In this paper we
+propose a new automated method called EchoGraphs for predicting ejection
+fraction and segmenting the left ventricle by detecting anatomical keypoints.
+Models for direct coordinate regression based on Graph Convolutional Networks
+(GCNs) are used to detect the keypoints. GCNs can learn to represent the
+cardiac shape based on local appearance of each keypoint, as well as global
+spatial and temporal structures of all keypoints combined. We evaluate our
+EchoGraphs model on the EchoNet benchmark dataset. Compared to semantic
+segmentation, GCNs show accurate segmentation and improvements in robustness
+and inference runtime. EF is computed simultaneously to segmentations and our
+method also obtains state-of-the-art ejection fraction estimation. Source code
+is available online: https://github.com/guybenyosef/EchoGraphs.",2207.02549v1
+2022-07-15,Probing helium reionization with kinetic Sunyaev Zel'dovich tomography,"Reionization of helium is expected to occur at redshifts $z\sim3$ and have
+important consequences for quasar populations, galaxy formation, and the
+morphology of the intergalactic medium, but there is little known empirically
+about the process. Here we show that kinetic Sunyaev-Zeldovich (kSZ)
+tomography, based on the combination of CMB measurements and galaxy surveys,
+can be used to infer the primordial helium abundance as well as the time and
+duration of helium reionization. We find a high-significance detection at
+${\sim10\sigma}$ can be expected from Vera Rubin Observatory and CMB-S4 in the
+near future. A more robust characterization of helium reionization will require
+next-generation experiments like MegaMapper (a proposed successor to DESI) and
+CMB-HD.",2207.07660v1
+2022-07-18,Optimal and tight Bell inequalities for state-independent contextuality sets,"Two fundamental quantum resources, nonlocality and contextuality, can be
+connected through Bell inequalities that are violated by state-independent
+contextuality (SI-C) sets. These Bell inequalities allow for applications that
+require simultaneous nonlocality and contextuality. However, for existing Bell
+inequalities, the nonlocality produced by SI-C sets is very sensitive to noise.
+This precludes experimental implementation. Here we identify the Bell
+inequalities for which the nonlocality produced by SI-C sets is optimal, i.e.,
+maximally robust to either noise or detection inefficiency, for the simplest
+SI-C [S. Yu and C. H. Oh, Phys. Rev. Lett. 108, 030402 (2012)] and
+Kochen-Specker sets [A. Cabello et al., Phys. Lett. A 212, 183 (1996)] and show
+that, in both cases, nonlocality is sufficiently resistant for experiments. Our
+work enables experiments that combine nonlocality and contextuality and
+therefore paves the way for applications that take advantage of their synergy.",2207.08850v3
+2022-07-25,Minimax Rates for High-dimensional Double Sparse Structure over $\ell_u(\ell_q)$-balls,"In this paper, we focus on the high-dimensional double sparse structure,
+where the parameter of interest simultaneously encourages group-wise sparsity
+and element-wise sparsity in each group. By combining the Gilbert-Varshamov
+bound and its variants, we develop a novel lower bound technique for the metric
+entropy of the parameter space, specifically tailored for the double sparse
+structure over $\ell_u(\ell_q)$-balls with $u,q \in [0,1]$. We prove lower
+bounds on the estimation error using an information-theoretic approach,
+leveraging our proposed lower bound technique and Fano's inequality. To
+complement the lower bounds, we establish matching upper bounds through a
+direct analysis of constrained least-squares estimators and utilize results
+from empirical processes. A significant finding of our study is the discovery
+of a phase transition phenomenon in the minimax rates for $u,q \in (0, 1]$.
+Furthermore, we extend the theoretical results to the double sparse regression
+model and determine its minimax rate for estimation error. To tackle double
+sparse linear regression, we develop the DSIHT (Double Sparse Iterative Hard
+Thresholding) algorithm, demonstrating its optimality in the minimax sense.
+Finally, we demonstrate the superiority of our method through numerical
+experiments.",2207.11888v2
+2022-08-02,Two-Stream Transformer Architecture for Long Video Understanding,"Pure vision transformer architectures are highly effective for short video
+classification and action recognition tasks. However, due to the quadratic
+complexity of self attention and lack of inductive bias, transformers are
+resource intensive and suffer from data inefficiencies. Long form video
+understanding tasks amplify data and memory efficiency problems in transformers
+making current approaches unfeasible to implement on data or memory restricted
+domains. This paper introduces an efficient Spatio-Temporal Attention Network
+(STAN) which uses a two-stream transformer architecture to model dependencies
+between static image features and temporal contextual features. Our proposed
+approach can classify videos up to two minutes in length on a single GPU, is
+data efficient, and achieves SOTA performance on several long video
+understanding tasks.",2208.01753v1
+2022-08-03,Mass and generalized Thiele equation of the magnetic skyrmion,"An analytical expression is obtained for the mass of an isolated magnetic
+skyrmion and its linearized equation of motion. The magnetic skyrmion is viewed
+as a topologically protected spin-wave soliton in the magnetic ultrathin films
+stabilized by the interfacial-Dzyaloshinskii-Moriya interaction. The equations
+of motion are derived from the Landau-Lifshitz-Gilbert equation for both the
+skyrmion charge and magnetization centers. They are generalized Thiele
+equations, including the gyro-term, dissipation term, external force,
+acceleration term with the tensorial mass, and time derivatives of the external
+forces. The equation of motion of the center of the skyrmion charge essentially
+shows the massless nature of the skyrmion. In contrast, the equation of motion
+for the magnetization center results in a finite mass that is in the same order
+as the Doring mass density for the linear domain wall. Furthermore, the time
+derivative of the external force predominantly contributes to the immediate
+response of the skyrmion motion, i.e., the mass-less property remains even
+after the skyrmion acquires its kinetic mass.
+  A micromagnetic simulation based on the LLG equation was performed for
+various magnetic parameters. Obtained trajectories at 0 K are compared with the
+theoretical predictions.",2208.01835v2
+2022-08-07,Transition state theory characterizes thin film macrospin dynamics driven by an oscillatory magnetic field: Inertial effects,"Understanding the magnetization switching process in ferromagnetic thin films
+is essential for many technological applications. We investigate the effects of
+periodic driving via magnetic fields on a macrospin system under explicit
+consideration of inertial dynamics. This is usually achieved by extending the
+Landau-Lifshitz-Gilbert equation with a term including the second time
+derivative of the magnetization. The dynamics of the magnetization switching
+can then be characterized by its switching rate. We apply methods from
+transition state theory for driven systems to resolve the rate of magnetization
+switching in this general case. In doing so, we find that magnetization
+exhibits resonance-like behavior under certain driving conditions, and it can
+be affected strongly by the system's relaxation rate.",2208.03613v1
+2022-08-09,HyperNST: Hyper-Networks for Neural Style Transfer,"We present HyperNST; a neural style transfer (NST) technique for the artistic
+stylization of images, based on Hyper-networks and the StyleGAN2 architecture.
+Our contribution is a novel method for inducing style transfer parameterized by
+a metric space, pre-trained for style-based visual search (SBVS). We show for
+the first time that such space may be used to drive NST, enabling the
+application and interpolation of styles from an SBVS system. The technical
+contribution is a hyper-network that predicts weight updates to a StyleGAN2
+pre-trained over a diverse gamut of artistic content (portraits), tailoring the
+style parameterization on a per-region basis using a semantic map of the facial
+regions. We show HyperNST to exceed state of the art in content preservation
+for our stylized content while retaining good style transfer performance.",2208.04807v1
+2022-08-19,Byzantine Consensus is Θ(n^2): The Dolev-Reischuk Bound is Tight even in Partial Synchrony! [Extended Version],"The Dolev-Reischuk bound says that any deterministic Byzantine consensus
+protocol has (at least) quadratic communication complexity in the worst case.
+While it has been shown that the bound is tight in synchronous environments, it
+is still unknown whether a consensus protocol with quadratic communication
+complexity can be obtained in partial synchrony. Until now, the most efficient
+known solutions for Byzantine consensus in partially synchronous settings had
+cubic communication complexity (e.g., HotStuff, binary DBFT).
+  This paper closes the existing gap by introducing SQuad, a partially
+synchronous Byzantine consensus protocol with quadratic worst-case
+communication complexity. In addition, SQuad is optimally-resilient and
+achieves linear worst-case latency complexity. The key technical contribution
+underlying SQuad lies in the way we solve view synchronization, the problem of
+bringing all correct processes to the same view with a correct leader for
+sufficiently long. Concretely, we present RareSync, a view synchronization
+protocol with quadratic communication complexity and linear latency complexity,
+which we utilize in order to obtain SQuad.",2208.09262v2
+2022-08-26,Randomised Composition and Small-Bias Minimax,"We prove two results about randomised query complexity $\mathrm{R}(f)$.
+First, we introduce a ""linearised"" complexity measure $\mathrm{LR}$ and show
+that it satisfies an inner-optimal composition theorem: $\mathrm{R}(f\circ g)
+\geq \Omega(\mathrm{R}(f) \mathrm{LR}(g))$ for all partial $f$ and $g$, and
+moreover, $\mathrm{LR}$ is the largest possible measure with this property. In
+particular, $\mathrm{LR}$ can be polynomially larger than previous measures
+that satisfy an inner composition theorem, such as the max-conflict complexity
+of Gavinsky, Lee, Santha, and Sanyal (ICALP 2019).
+  Our second result addresses a question of Yao (FOCS 1977). He asked if
+$\epsilon$-error expected query complexity $\bar{\mathrm{R}}_{\epsilon}(f)$
+admits a distributional characterisation relative to some hard input
+distribution. Vereshchagin (TCS 1998) answered this question affirmatively in
+the bounded-error case. We show that an analogous theorem fails in the
+small-bias case $\epsilon=1/2-o(1)$.",2208.12896v1
+2022-09-04,Lévy flights as an emergent phenomenon in a spatially extended system,"Anomalous diffusion and L\'evy flights, which are characterized by the
+occurrence of random discrete jumps of all scales, have been observed in a
+plethora of natural and engineered systems, ranging from the motion of
+molecules to climate signals. Mathematicians have recently unveiled mechanisms
+to generate anomalous diffusion, both stochastically and deterministically.
+However, there exists to the best of our knowledge no explicit example of a
+spatially extended system which exhibits anomalous diffusion without being
+explicitly driven by L\'evy noise. We show here that the
+Landau-Lifshitz-Gilbert equation, a stochastic partial differential equation
+(SPDE), despite only driven by Gaussian white noise, exhibits superdiffusive
+behaviour. The anomalous diffusion is an entirely emergent behaviour and
+manifests itself in jumps in the location of its travelling front solution.
+Using a collective coordinate approach we reduce the SPDE to a set of
+stochastic differential equations (SDEs) driven by Gaussian white noise. This
+allows us to identify the mechanism giving rise to the anomalous diffusion as
+random widening events of the front interface.",2209.01520v3
+2022-08-29,Probably Something: A Multi-Layer Taxonomy of Non-Fungible Tokens,"Purpose: This paper aims to establish a fundamental and comprehensive
+understanding of Non-Fungible Tokens (NFTs) by identifying and structuring
+common characteristics within a taxonomy. NFTs are hyped and increasingly
+marketed as essential building blocks of the Metaverse. However, the dynamic
+evolution of the NFT space has posed challenges for those seeking to develop a
+deep and comprehensive understanding of NFTs, their features, and capabilities.
+  Design/methodology/approach: Utilizing common guidelines for the creation of
+taxonomies, we developed (over three iterations), a multi-layer taxonomy based
+on workshops and interviews with 11 academic and 15 industry experts. Through
+an evaluation of 25 NFTs, we demonstrate the usefulness of our taxonomy.
+  Findings: The taxonomy has four layers, 14 dimensions and 42 characteristics,
+which describe NFTs in terms of reference object, token properties, token
+distribution, and realizable value.
+  Originality: Our framework is the first to systematically cover the emerging
+NFT phenomenon. It is concise yet extendible and presents many avenues for
+future research in a plethora of disciplines. The characteristics identified in
+our taxonomy are useful for NFT and Metaverse related research in Finance,
+Marketing, Law, and Information Systems. Additionally, the taxonomy can serve
+as an information source for policymakers as they consider NFT regulation.",2209.05456v1
+2022-09-19,Introducing the step Monte Carlo method for simulating dynamic properties,"In this work, we introduce a simple modification of the Monte Carlo
+algorithm, which we call step Monte Carlo (sMC). The sMC approach allows to
+simulate processes far from equilibrium and obtain information about the
+dynamic properties of the system under investigation. In the approach proposed
+here the probability of accepting the final (trial) state depends on the
+activation energy, not on the relative energy between the final and initial
+state. This barrier height is probed on an ongoing basis, by generating
+intermediate states along the path connecting the initial and trial positions.
+Importantly, to calculate the activation energy, our model only requires
+knowledge of the Hamiltonian without having to introduce additional input
+parameters such as transition rates etc. The details of sMC are explained for
+the case of a simple spin model. The comparison of its results with the ones
+obtained within the frame of stochastic Landau-Lifshitz-Gilbert indicates the
+correctness of sMC. In our opinion, the proposed here method can be applied to
+simulate other processes, for example dynamics of classical atoms and complex
+fluids, diffusion, nucleation, surface adsorption and crystal growth processes.",2209.08961v3
+2022-09-23,Logarithmically larger deletion codes of all distances,"The deletion distance between two binary words $u,v \in \{0,1\}^n$ is the
+smallest $k$ such that $u$ and $v$ share a common subsequence of length $n-k$.
+A set $C$ of binary words of length $n$ is called a $k$-deletion code if every
+pair of distinct words in $C$ has deletion distance greater than $k$. In 1965,
+Levenshtein initiated the study of deletion codes by showing that, for $k\ge 1$
+fixed and $n$ going to infinity, a $k$-deletion code $C\subseteq \{0,1\}^n$ of
+maximum size satisfies $\Omega_k(2^n/n^{2k}) \leq |C| \leq O_k( 2^n/n^k)$. We
+make the first asymptotic improvement to these bounds by showing that there
+exist $k$-deletion codes with size at least $\Omega_k(2^n \log n/n^{2k})$. Our
+proof is inspired by Jiang and Vardy's improvement to the classical
+Gilbert--Varshamov bounds. We also establish several related results on the
+number of longest common subsequences and shortest common supersequences of a
+pair of words with given length and deletion distance.",2209.11882v2
+2022-10-19,Generalised form of the magnetic anisotropy field in micromagnetic and atomistic spin models,"We present a general approach to the derivation of the effective anisotropy
+field which determines the dynamical behaviour of magnetic spins according to
+the Landau-Lifshitz-Gilbert equation. The approach is based on the gradient in
+spherical polar coordinates with the final results being expressed in Cartesian
+coordinates as usually applied in atomistic and micromagnetic model
+calculations. The approach is generally valid for all orders of anisotropies
+including higher order combinations of azimuthal and rotational anisotropies
+often found in functional magnetic materials such as permanent magnets and an
+emerging class of antiferromagnetic materials with applications in spintronics.
+Anisotropies are represented in terms of spherical harmonics which have the
+important property of rational temperature scaling. Effective field vectors are
+given for anisotropies up to sixth order, presenting a unified framework for
+implementing higher order magnetic anisotropies in numerical simulations.",2210.10916v4
+2022-10-27,Formal Semantics for the Halide Language,"We present the first formalization and metatheory of language soundness for a
+user-schedulable language, the widely used array processing language Halide.
+User-schedulable languages strike a balance between abstraction and control in
+high-performance computing by separating the specification of what a program
+should compute from a schedule for how to compute it. In the process, they make
+a novel language soundness claim: the result of a program should always be the
+same, regardless of how it is scheduled. This soundness guarantee is tricky to
+provide in the presence of schedules that introduce redundant recomputation and
+computation on uninitialized data, rather than simply reordering statements. In
+addition, Halide ensures memory safety through a compile-time bounds inference
+engine that determines safe sizes for every buffer and loop in the generated
+code, presenting a novel challenge: formalizing and analyzing a language
+specification that depends on the results of unreliable program synthesis
+algorithms. Our formalization has revealed flaws and led to improvements in the
+practical Halide system, and we believe it provides a foundation for the design
+of new languages and tools that apply programmer-controlled scheduling to other
+domains.",2210.15740v1
+2022-11-08,SLATE: A Sequence Labeling Approach for Task Extraction from Free-form Inked Content,"We present SLATE, a sequence labeling approach for extracting tasks from
+free-form content such as digitally handwritten (or ""inked"") notes on a virtual
+whiteboard. Our approach allows us to create a single, low-latency model to
+simultaneously perform sentence segmentation and classification of these
+sentences into task/non-task sentences. SLATE greatly outperforms a baseline
+two-model (sentence segmentation followed by classification model) approach,
+achieving a task F1 score of 84.4%, a sentence segmentation (boundary
+similarity) score of 88.4% and three times lower latency compared to the
+baseline. Furthermore, we provide insights into tackling challenges of
+performing NLP on the inking domain. We release both our code and dataset for
+this novel task.",2211.04454v2
+2022-11-10,Unifying the communicable disease spreading paradigm with Gompertzian growth,"A number of studies have shown that cumulative mortality followed a Gompertz
+curve in the initial Covid pandemic period, March-April 2020. We show that the
+Gompertz curve is incompatible with expected initial logistic growth curves as
+predicted by traditional Susceptible-Infected-Recovered (SIR) models, and
+propose a new theory which better explains the nature of the mortality
+characteristics based on a global biosphere disturbance. Second, we show that
+for the Gompertz curve to emerge, the disturbance has to act on everyone
+simultaneously, rejecting the possibility of a disease propagation stage.
+Third, we connect logistic growth with Gompertzian growth by augmenting the
+logistic growth equation with higher order interaction terms, and show that the
+SIR model family is compatible with Gompertzian growth only when all nodes in
+the transmission network communicate with infinite speed and interaction.
+Crucially, this augmentation must be accompanied by a causality-reversal where
+the source of growth is not the pool of infected but the pool of susceptible
+people. We thus find a novel bridge between logistic and Gompertzian growth,
+separate from the existing Richards model (also called $\theta$-logistic
+growth).",2211.05653v2
+2022-11-12,Helio2024 Science White Paper: ngGONG -- Future Ground-based Facilities for Research in Heliophysics and Space Weather Operational Forecast,"Long-term synoptic observations of the Sun are critical for advancing our
+understanding of Sun as an astrophysical object, understanding the solar
+irradiance and its role in solar-terrestrial climate, for developing predictive
+capabilities of solar eruptive phenomena and their impact on our home planet,
+and heliosphere in general, and as a data provider for the operational space
+weather forecast. We advocate for the development of a ground-based network of
+instruments provisionally called ngGONG to maintain critical observing
+capabilities for synoptic research in solar physics and for the operational
+space weather forecast.",2211.06712v1
+2022-11-14,SVS: Adversarial refinement for sparse novel view synthesis,"This paper proposes Sparse View Synthesis. This is a view synthesis problem
+where the number of reference views is limited, and the baseline between target
+and reference view is significant. Under these conditions, current radiance
+field methods fail catastrophically due to inescapable artifacts such 3D
+floating blobs, blurring and structural duplication, whenever the number of
+reference views is limited, or the target view diverges significantly from the
+reference views.
+  Advances in network architecture and loss regularisation are unable to
+satisfactorily remove these artifacts. The occlusions within the scene ensure
+that the true contents of these regions is simply not available to the model.
+In this work, we instead focus on hallucinating plausible scene contents within
+such regions. To this end we unify radiance field models with adversarial
+learning and perceptual losses. The resulting system provides up to 60%
+improvement in perceptual accuracy compared to current state-of-the-art
+radiance field models on this problem.",2211.07301v1
+2022-11-15,Viscosity of pure-glue QCD from the lattice,"We calculate shear viscosity and bulk viscosity in SU(3) gauge theory on the
+lattice at $1.5 \,T_c$. The viscosities are extracted via a Kubo formula from
+the reconstructed spectral function which we determine from the Euclidean-time
+dependence of the corresponding channel of the energy-momentum tensor
+correlators. We obtain unprecedented precision for the correlators by applying
+gradient flow and blocking methods. The correlators are extrapolated to the
+continuum and then to zero flow time. To extract the viscosities we fit
+theoretically inspired models to the lattice data and crosscheck the fit
+results using the Backus Gilbert method. The final estimates for shear and bulk
+viscosity are $\eta/s = 0.15-0.48$ and $\zeta/s = 0.017-0.059$.",2211.08230v2
+2022-11-15,Nonlinear chiral photocurrent in parity-violating magnetic Weyl semimetals,"The strong correlation between the non-trivial band topology and the magnetic
+texture makes magnetic Weyl semimetals excellent candidates for the
+manipulation and detection of magnetization dynamics. The parity violation
+together with the Pauli blocking cause only one Weyl node to contribute to the
+photocurrent response, which in turn affects the magnetic texture due to the
+spin transfer torque. Utilizing the Landau-Lifshitz-Gilbert equation and the
+spin-transfer torque in non-centrosymmetric Weyl magnets, we show that the
+chiral photocurrent rotates the magnetization from the easy c axis to the a or
+b axis, which leads to an exotic current next to the photocurrent response. The
+chiral photocurrent is calculated in the context of quantum kinetic theory and
+it has a strong resonance on the order of mA/W near the Weyl nodes, the
+magnitude of which is controlled by the momentum relaxation time. Remarkably,
+we study the influence of magnetic texture dynamics on the topological
+nonlinear photocurrent response, including shift and injection currents along
+with the new chiral photocurrent, and show that both the magnitude and the
+in-plane orientation of the chiral photocurrent are strongly correlated with
+the direction of the magnetic moments.",2211.08521v1
+2022-11-17,3D Interconnected Magnetic Nanowire Networks as Potential Integrated Multistate Memristors,"Interconnected magnetic nanowire (NW) networks offer a promising platform for
+3-dimensional (3D) information storage and integrated neuromorphic computing.
+Here we report discrete propagation of magnetic states in interconnected Co
+nanowire networks driven by magnetic field and current, manifested in distinct
+magnetoresistance (MR) features. In these networks, when only a few
+interconnected NWs were measured, multiple MR kinks and local minima were
+observed, including a significant minimum at a positive field during the
+descending field sweep. Micromagnetic simulations showed that this unusual
+feature was due to domain wall (DW) pinning at the NW intersections, which was
+confirmed by off-axis electron holography imaging. In a complex network with
+many intersections, sequential switching of nanowire sections separated by
+interconnects was observed, along with stochastic characteristics. The
+pinning/depinning of the DWs can be further controlled by the driving current
+density. These results illustrate the promise of such interconnected networks
+as integrated multistate memristors.",2211.09687v2
+2022-11-22,Enabling On-Demand Cyber-Physical Control Applications with UAV Access Points,"Achieving cyber-physical control over a wireless channel requires satisfying
+both the timeliness of a single packet and preserving the latency reliability
+across several consecutive packets. To satisfy those requirements as an
+ubiquitous service requires big infrastructural developments, or flexible
+on-demand equipment such as UAVs. To avoid the upfront cost in terms of finance
+and energy, this paper analyzes the capability of UAV access points (UAVAPs) to
+satisfy the requirements for cyber-physical traffic. To investigate this, we
+perform a Gilbert-Eliott burst-error analysis that is analytically derived as a
+combination of two separate latency measurement campaigns and provide an
+upper-bound analysis of the UAVAP system. The analysis is centered around a
+UAVAP that uses its LTE connection to reach the backhaul, while providing
+service to ground nodes (GNs) with a Wi-Fi access point (AP). Thus, we combine
+both measurement campaigns to analyze the plausibility of the described setup
+in casual, crowded or mixed network settings.",2211.12249v1
+2022-11-30,SuSpect3: A C++ Code for the Supersymmetric and Higgs Particle Spectrum of the MSSM,"We present the program SuSpect3 that calculates the masses and couplings of
+the Higgs and supersymmetric particles predicted by the Minimal Supersymmetric
+Standard Model (MSSM). The model is implemented in both its non-constrained
+version, the MSSM, and its constrained versions, such as the minimal
+supergravity and the gauge or anomaly mediated supersymmetry breaking models,
+in which the soft supersymmetry-breaking parameters obey certain universal
+boundary conditions at the high energy scale. The low energy parameters are
+then obtained using renormalization group equations and electroweak symmetry
+breaking, and all the dominant radiative corrections have been consistently
+implemented. SuSpect3 is a major rewrite, in C++ object oriented programming,
+of the FORTRAN code SuSpect. It includes all the features of the earlier code
+in an improved and updated manner, and involves new options such as compressed
+SUSY scenarios, an MSSM-inflation model and the possibility of using the
+observed Higgs mass as an input. The main features and the use of the program
+are explained.",2211.16956v2
+2022-12-06,Ground-based Synoptic Studies of the Sun,"Ground-based synoptic solar observations provide critical contextual data
+used to model the large-scale state of the heliosphere. The next decade will
+see a combination of ground-based telescopes and space missions that will study
+our Sun's atmosphere microscopic processes with unprecedented detail. This
+white paper describes contextual observations from a ground-based network
+needed to fully exploit this new knowledge of the underlying physics that leads
+to the magnetic linkages between the heliosphere and the Sun. This combination
+of a better understanding of small-scale processes and the appropriate global
+context will enable a physics-based approach to Space Weather comparable to
+Terrestrial Weather forecasting.",2212.03247v2
+2022-12-14,Non-uniform Superlattice Magnetic Tunnel Junctions,"We propose a new class of non-uniform superlattice magnetic tunnel junctions
+(Nu-SLTJs) with the Linear, Gaussian, Lorentzian, and P\""oschl-teller width and
+height based profiles manifesting a sizable enhancement in the TMR($\approx
+10^4-10^6\%$) with a significant suppression in the switching bias($\approx$9
+folds) owing to the physics of broad-band spin filtering. By exploring the
+negative differential resistance region in the current-voltage characteristics
+of the various Nu-SLTJs, we predict the Nu-SLTJs offer the fastest spin
+transfer torque switching in the order of a few hundred picoseconds. We
+self-consistently employ the atomistic non-equilibrium Green's function
+formalism coupled with the Landau-Lifshitz-Gilbert-Slonczewski equation to
+evaluate the device performance of the various Nu-SLTJs. We also present the
+design of minimal three-barrier Nu-SLTJs having significant TMR($\approx
+10^4\%$) and large spin current for ease of device fabrication. We hope that
+the class of Nu-SLTJs proposed in this work may lay the bedrock to embark on
+the exhilarating voyage of exploring various non-uniform superlattices for the
+next generation of spintronic devices.",2212.07202v2
+2022-12-20,A combinatorial proof of a tantalizing symmetry on Catalan objects,"We investigate a tantalizing symmetry on Catalan objects. In terms of Dyck
+paths, this symmetry is interpreted in the following way: if $w_{n,k,m}$ is the
+number of Dyck paths of semilength $n$ with $k$ occurrences of $UD$ and $m$
+occurrences of $UUD$, then $w_{2k+1,k,m}=w_{2k+1,k,k+1-m}$. We give two proofs
+of this symmetry: an algebraic proof using generating functions, and a
+combinatorial proof which makes heavy use of the cycle lemma and an alternate
+interpretation of the numbers $w_{n,k,m}$ using plane trees. In particular, our
+combinatorial proof expresses the numbers $w_{2k+1,k,m}$ in terms of Narayana
+numbers, and we generalize this to a relationship between the numbers
+$w_{n,k,m}$ and a family of generalized Narayana numbers due to Callan. Some
+further generalizations and applications of our combinatorial proofs are
+explored. Finally, we investigate properties of the polynomials $W_{n,k}(t)=
+\sum_{m=0}^k w_{n,k,m} t^m$, including real-rootedness, $\gamma$-positivity,
+and a symmetric decomposition.",2212.10586v1
+2022-12-30,Asymptotic Analysis of Harmonic Maps With Prescribed Singularities,"Motivated by stationary vacuum solutions of the Einstein field equations, we
+study singular harmonic maps from domains of 3-dimensional Euclidean space to
+the hyperbolic plane having bounded hyperbolic distance to Kerr harmonic maps.
+In the degenerate case, we prove that every such harmonic map admits a unique
+tangent harmonic map at the extreme black hole horizon. The possible tangent
+maps are classified and shown to be shifted 'extreme Kerr' geodesics in the
+hyperbolic plane that depend on two parameters, one determined by angular
+momentum and another by conical singularities. In addition, rates of
+convergence to the tangent map are established. Similarly, expansions in the
+asymptotically flat end are presented. These results, together with those of
+Li-Tian and Weinstein, provide a complete regularity theory for harmonic maps
+from $\mathbb R^3\setminus z\text{-axis}$ to $\mathbb H^2$ with prescribed
+singularities. Lastly, the analysis is utilized to prove existence of the so
+called near horizon limit, and to compute the associated near horizon
+geometries of extreme black holes.",2212.14826v1
+2023-01-06,Measuring a Priori Voting Power -- Taking Delegations Seriously,"We introduce new power indices to measure the a priori voting power of voters
+in liquid democracy elections where an underlying network restricts
+delegations. We argue that our power indices are natural extensions of the
+standard Penrose-Banzhaf index in simple voting games. We show that computing
+the criticality of a voter is #P-hard even when voting weights are
+polynomially-bounded in the size of the instance. However, for specific
+settings, such as when the underlying network is a bipartite or complete graph,
+recursive formulas can compute these indices for weighted voting games in
+pseudo-polynomial time. We highlight their theoretical properties and provide
+numerical results to illustrate how restricting the possible delegations can
+alter voters' voting power.",2301.02462v4
+2023-01-10,The spectral reconstruction of inclusive rates,"A recently re-discovered variant of the Backus-Gilbert algorithm for spectral
+reconstruction enables the controlled determination of smeared spectral
+densities from lattice field theory correlation functions. A particular
+advantage of this approach is the \emph{a priori} specification of the kernel
+with which the underlying spectral density is smeared, allowing for variation
+of its peak position, smearing width, and functional form. If the unsmeared
+spectral density is sufficiently smooth in the neighborhood of a particular
+energy, it can be obtained from an extrapolation to zero smearing-kernel width
+at fixed peak position. A natural application for this approach is scattering
+processes summed over all hadronic final states. As a proof-of-principle test,
+an inclusive rate is computed in the two-dimensional O(3) sigma model from a
+two-point correlation function of conserved currents. The results at finite and
+zero smearing radius are in good agreement with the known analytic form up to
+energies at which 40-particle states contribute, and are sensitive to the
+4-particle contribution to the inclusive rate. The straight-forward adaptation
+to compute the $R$-ratio in lattice QCD from two-point functions of the
+electromagnetic current is briefly discussed.",2301.04072v1
+2023-01-12,Redundancy of Codes with Graph Constraints,"In this paper, we study the redundancy of linear codes with graph
+constraints. First we consider linear parity check codes based on bipartite
+graphs with diversity and with generalized graph constraints. We describe
+sufficient conditions on the constraint probabilities and use the probabilistic
+method to obtain linear codes that achieve the Gilbert-Varshamov redundancy
+bound in addition to satisfying the constraints and the diversity index. In the
+second part we consider a generalization of graph capacity which we call as the
+fractional graph capacity and use the probabilistic method to determine bounds
+on the fractional capacity for arbitrary graphs. Specifically, we establish an
+upper bound in terms of the full graph capacity and a lower bound in terms of
+the average and maximum vertex degree of the graph.",2301.04808v1
+2023-01-12,Magnetic-field-free nonreciprocal transport in graphene multi-terminal Josephson junctions,"Nonreciprocal superconducting devices have attracted growing interest in
+recent years as they potentially enable directional charge transport for
+applications in superconducting quantum circuits. Specifically, the
+superconducting diode effect has been explored in two-terminal devices that
+exhibit superconducting transport in one current direction while showing
+dissipative transport in the opposite direction. Here, we exploit
+multi-terminal Josephson junctions (MTJJs) to engineer magnetic-field-free
+nonreciprocity in multi-port networks. We show that when treated as a two-port
+electrical network, a three-terminal Josephson junction (JJ) with an asymmetric
+graphene region exhibits reconfigurable two-port nonreciprocity. We observe
+nonreciprocal (reciprocal) transport between superconducting terminals with
+broken (preserved) spatial mirror symmetry. We explain our observations by
+considering a circuit-network of JJs with different critical currents.",2301.05081v3
+2023-01-24,Recent Results from the FASTSUM Collaboration,"The FASTSUM Collaboration has developed a comprehensive research programme in
+thermal QCD using 2+1 flavour, anisotropic ensembles. In this talk, we
+summarise some of our recent results including thermal hadron spectrum
+calculations using our ``Generation 2L'' ensembles which have pion masses of
+239(1) MeV. These include open charm mesons and charm baryons. We also
+summarise our work using the Backus Gilbert approach to determining the
+spectral function of the NRQCD bottomonium system. Finally, we review our
+determination of the interquark potential in the same system, but using our
+``Generation 2'' ensembles which have heavier pion masses of 384(4) MeV.",2301.10282v1
+2023-01-27,Women's Perspectives on Harm and Justice after Online Harassment,"Social media platforms aspire to create online experiences where users can
+participate safely and equitably. However, women around the world experience
+widespread online harassment, including insults, stalking, aggression, threats,
+and non-consensual sharing of sexual photos. This article describes women's
+perceptions of harm associated with online harassment and preferred platform
+responses to that harm. We conducted a survey in 14 geographic regions around
+the world (N = 3,993), focusing on regions whose perspectives have been
+insufficiently elevated in social media governance decisions (e.g. Mongolia,
+Cameroon). {Results show} that, on average, women perceive greater harm
+associated with online harassment than men, especially for non-consensual image
+sharing. Women also prefer most platform responses compared to men, especially
+removing content and banning users; however, women are less favorable towards
+payment as a response. Addressing global gender-based violence online requires
+understanding how women experience online harms and how they wish for it to be
+addressed. This is especially important given that the people who build and
+govern technology are not typically those who are most likely to experience
+online harms.",2301.11733v1
+2023-02-02,Thermal and atomic effects on coupled-channels heavy-ion fusion,"Stellar nuclear fusion reactions take place in a hot, dense plasma within
+stars. To account for the effect of these environments, the theory of open
+quantum systems is used to conduct pioneering studies of thermal and atomic
+effects on fusion probability at a broad range of temperatures and densities.
+Since low-lying excited states are more likely to be populated at stellar
+temperatures and increase nuclear plasma interaction rates, a 188Os nucleus was
+used as a target that interacts with an inert 16O projectile. Key results
+showed thermal effects yield an average increase in fusion probability of 15.5%
+and 36.9% for our test nuclei at temperatures of 0.1 and 0.5 MeV respectively,
+compared to calculations at zero temperature. Thermal effects could be tested
+in a laboratory using targets prepared in excited states as envisaged in
+facilities exploiting laser-nucleus interactions.",2302.01272v2
+2023-02-02,Topological data analysis reveals differences between simulated galaxies and dark matter haloes,"We use topological summaries based on Betti curves to characterize the
+large-scale spatial distribution of simulated dark matter haloes and galaxies.
+Using the IllustrisTNG and CAMELS-SAM simulations, we show that the topology of
+the galaxy distribution is significantly different from the topology of the
+dark matter halo distribution. Further, there are significant differences
+between the distributions of star-forming and quiescent galaxies. These
+topological differences are broadly consistent across all simulations, while at
+the same time there are noticeable differences when comparing between different
+models. Finally, using the CAMELS-SAM simulations, we show that the topology of
+the quiescent galaxies in particular depends strongly on the amount of
+supernova feedback. These results suggest that topological summary statistics
+could be used to help better understand the processes of galaxy formation and
+evolution.",2302.01363v2
+2023-02-13,Zero-frequency chiral magnonic edge states protected by non-equilibrium topology,"Topological bosonic excitations must, in contrast to their fermionic
+counterparts, appear at finite energies. This is a key challenge for magnons,
+as it prevents straightforward excitation and detection of
+topologically-protected magnonic edge states and their use in magnonic devices.
+In this work, we show that in a non-equilibrium state, in which the
+magnetization is pointing against the external magnetic field, the
+topologically-protected chiral edge states in a magnon Chern insulator can be
+lowered to zero frequency, making them directly accessible by existing
+experimental techniques. We discuss the spin-orbit torque required to stabilize
+this non-equilibrium state, and show explicitly using numerical
+Landau-Lifshitz-Gilbert simulations that the edge states can be excited with a
+microwave field. Finally, we consider a propagating spin wave spectroscopy
+experiment, and demonstrate that the edge states can be directly detected.",2302.06597v3
+2023-02-15,Reliable optimization of arbitrary functions over quantum measurements,"As the connection between classical and quantum worlds, quantum measurements
+play a unique role in the era of quantum information processing. Given an
+arbitrary function of quantum measurements, how to obtain its optimal value is
+often considered as a basic yet important problem in various applications.
+Typical examples include but not limited to optimizing the likelihood functions
+in quantum measurement tomography, searching the Bell parameters in Bell-test
+experiments, and calculating the capacities of quantum channels. In this work,
+we propose reliable algorithms for optimizing arbitrary functions over the
+space of quantum measurements by combining the so-called Gilbert's algorithm
+for convex optimization with certain gradient algorithms. With extensive
+applications, we demonstrate the efficacy of our algorithms with both convex
+and nonconvex functions.",2302.07534v1
+2023-02-18,Distributed Optimization for Reactive Power Sharing and Stability of Inverter-Based Resources Under Voltage Limits,"Reactive power sharing and containment of voltages within limits for
+inverter-based resources (IBRs) are two important, yet coupled objectives in ac
+networks. In this article, we propose a distributed control technique to
+simultaneously achieve these objectives. Our controller consists of two
+components: a purely local nonlinear integral controller which adjusts the IBR
+voltage setpoint, and a distributed primal-dual optimizer that coordinates
+reactive power sharing between the IBRs. The controller prioritizes the voltage
+containment objective over reactive power sharing at all points in time;
+excluding the IBRs with saturated voltages, it provides reactive power sharing
+among all the IBRs. Considering the voltage saturation and the coupling between
+voltage and angle dynamics, a formal closed-loop stability analysis based on
+singular perturbation theory is provided, yielding practical tuning guidance
+for the overall control system. To validate the effectiveness of the proposed
+controller for different case studies, we apply it to a low-voltage microgrid
+and a microgrid adapted from the CIGRE medium-voltage network benchmark, both
+simulated in the MATLAB/Simulink environment.",2302.09241v2
+2023-02-21,Micromagnetic study of inertial spin waves in ferromagnetic nanodots,"Here we report the possibility to excite ultra-short spin waves in
+ferromagnetic thin-films by using time-harmonic electromagnetic fields with
+terahertz frequency. Such ultra-fast excitation requires to include inertial
+effects in the description of magnetization dynamics. In this respect, we
+consider the inertial Landau-Lifshitz-Gilbert (iLLG) equation and develop
+analytical theory for exchange-dominated inertial spin waves. The theory
+predicts a finite limit for inertial spin wave propagation velocity, as well as
+spin wave spatial decay and lifetime as function of material parameters. Then,
+guided by the theory, we perform numerical micromagnetic simulations that
+demonstrate the excitation of ultra-short inertial spin waves (20 nm long)
+propagating at finite speed in a confined magnetic nanodot. The results are in
+agreement with the theory and provide the order of magnitude of quantities
+observable in realistic ultra-fast dynamics experiments.",2302.10759v2
+2023-03-04,Dynamic Modeling and Validation of Soft Robotic Snake Locomotion,"Soft robotic snakes made of compliant materials can continuously deform their
+bodies and, therefore, mimic the biological snakes' flexible and agile
+locomotion gaits better than their rigid-bodied counterparts. Without wheel
+support, to date, soft robotic snakes are limited to emulating planar
+locomotion gaits, which are derived via kinematic modeling and tested on
+robotic prototypes. Given that the snake locomotion results from the reaction
+forces due to the distributed contact between their skin and the ground, it is
+essential to investigate the locomotion gaits through efficient dynamic models
+capable of accommodating distributed contact forces. We present a complete
+spatial dynamic model that utilizes a floating-base kinematic model with
+distributed contact dynamics for a pneumatically powered soft robotic snake. We
+numerically evaluate the feasibility of the planar and spatial rolling gaits
+utilizing the proposed model and experimentally validate the corresponding
+locomotion gait trajectories on a soft robotic snake prototype. We
+qualitatively and quantitatively compare the numerical and experimental results
+which confirm the validity of the proposed dynamic model.",2303.02291v1
+2023-03-20,Semiparametric inference for relative heterogeneous vaccine efficacy between strains in observational case-only studies,"The aim of this manuscript is to explore semiparametric methods for inferring
+subgroup-specific relative vaccine efficacy in a partially vaccinated
+population against multiple strains of a virus. We consider methods for
+observational case-only studies with informative missingness in viral strain
+type due to vaccination status, pre-vaccination variables, and also
+post-vaccination factors such as viral load. We establish general causal
+conditions under which the relative conditional vaccine efficacy between
+strains can be identified nonparametrically from the observed data-generating
+distribution. Assuming that the relative strain-specific conditional vaccine
+efficacy has a known parametric form, we propose semiparametric asymptotically
+linear estimators of the parameters based on targeted (debiased) machine
+learning estimators for partially linear logistic regression models. Finally,
+we apply our methods to estimate the relative strain-specific conditional
+vaccine efficacy in the ENSEMBLE COVID-19 vaccine trial.",2303.11462v1
+2023-03-16,Factoring the Matrix of Domination: A Critical Review and Reimagination of Intersectionality in AI Fairness,"Intersectionality is a critical framework that, through inquiry and praxis,
+allows us to examine how social inequalities persist through domains of
+structure and discipline. Given AI fairness' raison d'etre of ""fairness"", we
+argue that adopting intersectionality as an analytical framework is pivotal to
+effectively operationalizing fairness. Through a critical review of how
+intersectionality is discussed in 30 papers from the AI fairness literature, we
+deductively and inductively: 1) map how intersectionality tenets operate within
+the AI fairness paradigm and 2) uncover gaps between the conceptualization and
+operationalization of intersectionality. We find that researchers
+overwhelmingly reduce intersectionality to optimizing for fairness metrics over
+demographic subgroups. They also fail to discuss their social context and when
+mentioning power, they mostly situate it only within the AI pipeline. We: 3)
+outline and assess the implications of these gaps for critical inquiry and
+praxis, and 4) provide actionable recommendations for AI fairness researchers
+to engage with intersectionality in their work by grounding it in AI
+epistemology.",2303.17555v2
+2023-04-04,Direct in situ determination of the surface area and structure of deposited metallic lithium within lithium metal batteries using ultra small and small angle neutron scattering,"Despite being the major cause of battery safety issues and detrimental
+performance, a comprehensive growth mechanism for metallic lithium deposited at
+electrode surfaces in lithium metal batteries remains elusive. While lithium
+surface morphology is often derived indirectly, here, detailed information is
+directly obtained using in situ small and ultra-small angle neutron scattering,
+in bulk and non-destructively. Features of 1-10 um and 100-300 nm are
+identified; the latter contribute to most of the surface area and their size
+inversely correlates to applied current density. Surface area per unit volume
+increases continuously during charging from 1-4 h at 2 mA/cm2 but more slowly
+during discharge. Comparatively higher values are reached after just 1 h at 20
+mA/cm2 which remain constant in subsequent cycles. Such quantitative insight
+into the processes of metallic lithium growth within batteries may enable the
+development of safer high performance lithium metal batteries.",2304.01557v1
+2023-04-10,EKILA: Synthetic Media Provenance and Attribution for Generative Art,"We present EKILA; a decentralized framework that enables creatives to receive
+recognition and reward for their contributions to generative AI (GenAI). EKILA
+proposes a robust visual attribution technique and combines this with an
+emerging content provenance standard (C2PA) to address the problem of synthetic
+image provenance -- determining the generative model and training data
+responsible for an AI-generated image. Furthermore, EKILA extends the
+non-fungible token (NFT) ecosystem to introduce a tokenized representation for
+rights, enabling a triangular relationship between the asset's Ownership,
+Rights, and Attribution (ORA). Leveraging the ORA relationship enables creators
+to express agency over training consent and, through our attribution model, to
+receive apportioned credit, including royalty payments for the use of their
+assets in GenAI.",2304.04639v1
+2023-04-11,NeAT: Neural Artistic Tracing for Beautiful Style Transfer,"Style transfer is the task of reproducing the semantic contents of a source
+image in the artistic style of a second target image. In this paper, we present
+NeAT, a new state-of-the art feed-forward style transfer method. We
+re-formulate feed-forward style transfer as image editing, rather than image
+generation, resulting in a model which improves over the state-of-the-art in
+both preserving the source content and matching the target style. An important
+component of our model's success is identifying and fixing ""style halos"", a
+commonly occurring artefact across many style transfer techniques. In addition
+to training and testing on standard datasets, we introduce the BBST-4M dataset,
+a new, large scale, high resolution dataset of 4M images. As a component of
+curating this data, we present a novel model able to classify if an image is
+stylistic. We use BBST-4M to improve and measure the generalization of NeAT
+across a huge variety of styles. Not only does NeAT offer state-of-the-art
+quality and generalization, it is designed and trained for fast inference at
+high resolution.",2304.05139v1
+2023-04-12,ALADIN-NST: Self-supervised disentangled representation learning of artistic style through Neural Style Transfer,"Representation learning aims to discover individual salient features of a
+domain in a compact and descriptive form that strongly identifies the unique
+characteristics of a given sample respective to its domain. Existing works in
+visual style representation literature have tried to disentangle style from
+content during training explicitly. A complete separation between these has yet
+to be fully achieved. Our paper aims to learn a representation of visual
+artistic style more strongly disentangled from the semantic content depicted in
+an image. We use Neural Style Transfer (NST) to measure and drive the learning
+signal and achieve state-of-the-art representation learning on explicitly
+disentangled metrics. We show that strongly addressing the disentanglement of
+style and content leads to large gains in style-specific metrics, encoding far
+less semantic information and achieving state-of-the-art accuracy in downstream
+multimodal applications.",2304.05755v2
+2023-04-18,"UPGPT: Universal Diffusion Model for Person Image Generation, Editing and Pose Transfer","Text-to-image models (T2I) such as StableDiffusion have been used to generate
+high quality images of people. However, due to the random nature of the
+generation process, the person has a different appearance e.g. pose, face, and
+clothing, despite using the same text prompt. The appearance inconsistency
+makes T2I unsuitable for pose transfer. We address this by proposing a
+multimodal diffusion model that accepts text, pose, and visual prompting. Our
+model is the first unified method to perform all person image tasks -
+generation, pose transfer, and mask-less edit. We also pioneer using small
+dimensional 3D body model parameters directly to demonstrate new capability -
+simultaneous pose and camera view interpolation while maintaining the person's
+appearance.",2304.08870v2
+2023-05-02,The Pseudoinverse of $A=CR$ is $A^+=R^+C^+$ (?),"This paper gives three formulas for the pseudoinverse of a matrix product $A
+= CR$. The first is sometimes correct, the second is always correct, and the
+third is almost never correct. But that third randomized pseudoinverse $A^+_r$
+may be very useful when $A$ is a very large matrix.
+  1. $A^+ = R^+C^+$ when $A = CR$ and $C$ has independent columns and $R$ has
+independent rows.
+  2. $A^+ = (C^+CR)^+(CRR^+)^+$ is always correct.
+  3. $A^+_r = (P^TCR)^+P^TCRQ(CRQ)^+ = A^+$ only when $\mathrm{rank}(P^TA) =
+\mathrm{rank}(AQ) = \mathrm{rank}(A)$ with $A = CR$.",2305.01716v3
+2023-05-10,Symmetry and nonlinearity of spin wave resonance excited by focused surface acoustic waves,"The use of a complex ferromagnetic system to manipulate GHz surface acoustic
+waves is a rich current topic under investigation, but the high-power nonlinear
+regime is under-explored. We introduce focused surface acoustic waves, which
+provide a way to access this regime with modest equipment. Symmetry of the
+magneto-acoustic interaction can be tuned by interdigitated transducer design
+which can introduce additional strain components. Here, we compare the impact
+of focused acoustic waves versus standard unidirectional acoustic waves in
+significantly enhancing the magnon-phonon coupling behavior. Analytical
+simulation results based on modified Landau-Lifshitz-Gilbert theory show good
+agreement with experimental findings. We also report nonlinear input power
+dependence of the transmission through the device. This experimental
+observation is supported by the micromagnetic simulation using mumax3 to model
+the nonlinear dependence. These results pave the way for extending the
+understanding and design of acoustic wave devices for exploration of
+acoustically driven spin wave resonance physics.",2305.06259v1
+2023-05-16,Phase locking in voltage-controlled parametric oscillator,"A recent experimental demonstration of a parametric magnetization oscillation
+excited by applying a microwave voltage to a ferromagnetic metal will be
+applicable not only to a new magnetization switching method but also to
+bio-inspired computing. It should be, however, noted that a phase of the
+parametric magnetization oscillation is not uniquely locked, related to the
+fact that a frequency of the microwave voltage is twice the value of the
+magnetization oscillation. There are two possible phases in the parametric
+oscillation state, and which of the two is realized depends on the initial
+condition of the magnetization. Here, we examine two approaches to lock the
+phase uniquely. One is to suppress the distribution of the initial state by
+enhancing the perpendicular magnetic anisotropy before applying microwave
+voltage, and the other is to use a sweeping frequency. Through numerical
+simulation of the Landau-Lifshitz-Gilbert equation and quantification of locked
+rate, we find that the sweeping frequency is more effective to lock the phase
+of the parametric magnetization oscillation.",2305.09143v1
+2023-05-16,Non-periodic input-driven magnetization dynamics in voltage-controlled parametric oscillator,"Input-driven dynamical systems have attracted attention because their
+dynamics can be used as resources for brain-inspired computing. The recent
+achievement of human-voice recognition by spintronic oscillator also utilizes
+an input-driven magnetization dynamics. Here, we investigate an excitation of
+input-driven chaos in magnetization dynamics by voltage controlled magnetic
+anisotropy effect. The study focuses on the parametric magnetization
+oscillation induced by a microwave voltage and investigates the effect of
+random-pulse input on the oscillation behavior. Solving the
+Landau-Lifshitz-Gilbert equation, temporal dynamics of the magnetization and
+its statistical character are evaluated. In a weak perturbation limit, the
+temporal dynamics of the magnetization are mainly determined by the input
+signal, which is classified as input-driven synchronization. In a large
+perturbation limit, on the other hand, chaotic dynamics are observed, where the
+dynamical response is sensitive to the initial state. The existence of chaos is
+also identified by the evaluation of the Lyapunov exponent.",2305.09151v1
+2023-05-23,Approaches to inclusive semileptonic $B_{(s)}$-meson decays from Lattice QCD,"We address the nonperturbative calculation of the inclusive decay rate of
+semileptonic $B_{(s)}$-meson decays from lattice QCD. Precise Standard-Model
+predictions are key ingredients in searches for new physics, and this type of
+computation may eventually provide new insight into the long-standing tension
+between the inclusive and exclusive determinations of the
+Cabibbo-Kobayashi-Maskawa (CKM) matrix elements $|V_{cb}|$ and $|V_{ub}|$. We
+present results from a pilot lattice computation for $B_s \rightarrow X_c\, l
+\nu_l$, where the initial $b$ quark described by the relativistic-heavy-quark
+(RHQ) formalism on the lattice and the other valence quarks discretised with
+domain-wall fermions are simulated approximately at their physical quark
+masses. We compare two different methods for computing the decay rate from
+lattice data of Euclidean $n$-point functions, namely Chebyshev and
+Backus-Gilbert approaches. We further study how much the ground-state meson
+dominates the inclusive decay rate and indicate our strategy towards a
+computation with a more comprehensive systematic error budget.",2305.14092v2
+2023-05-25,Crystallization dynamics of magnetic skyrmions in a frustrated itinerant magnet,"We investigate the phase ordering kinetics of skyrmion lattice (SkL) in a
+metallic magnet. The SkL can be viewed as a superposition of magnetic stripes
+whose periods are determined by the quasi-nesting wave vectors of the
+underlying Fermi surface. An effective magnetic Hamiltonian that describes the
+electron-mediated spin-spin interaction is obtained for a two-dimensional s-d
+model with the Rashba spin-orbit coupling. Large-scale Landau-Lifshitz-Gilbert
+dynamics simulations based on the effective spin Hamiltonian reveal a two-stage
+phase ordering of the SkL phase after a thermal quench. The initial fast
+crystallization of skyrmions is followed by a slow relaxation dominated by the
+annihilation dynamics of dislocations, which are topological defects of the
+constituent magnetic stripe orders. The late-stage phase ordering also exhibits
+a dynamical scaling symmetry. We further show that the annihilation of
+dislocations follows a power-law time dependence with a logarithmic correction
+that depends on magnetic fields. Implications of our results for SkL phases in
+magnetic materials are also discussed.",2305.16182v1
+2023-05-31,Magnetization dynamics in a three-dimensional interconnected nanowire array,"Three-dimensional magnetic nanostructures have recently emerged as artificial
+magnetic material types with unique properties bearing potential for
+applications, including magnonic devices. Interconnected magnetic nanowires are
+a sub-category within this class of materials that is attracting particular
+interest. We investigate the high-frequency magnetization dynamics in a cubic
+array of cylindrical magnetic nanowires through micromagnetic simulations based
+on a frequency-domain formulation of the linearized Landau-Lifshitz-Gilbert
+equation. The small-angle high-frequency magnetization dynamics excited by an
+external oscillatory field displays clear resonances at distinct frequencies.
+These resonances are identified as oscillations connected to specific geometric
+features and micromagnetic configurations. The geometry- and
+configuration-dependence of the nanowire array's absorption spectrum
+demonstrates the potential of such magnetic systems for tuneable and
+reprogrammable magnonic applications.",2306.00174v1
+2023-06-12,Continuum Limit of Spin Dynamics on Hexagonal Lattice,"Compared to their three-dimensional counterparts, two-dimensional materials
+exhibit intriguing electronic and magnetic properties. Notable examples include
+twisted graphene's superconducting states and chromium trichloride's meron spin
+textures. Understanding nontrivial topological spin textures is crucial for
+magnetization dynamics and spintronic technologies. In this study, we analyze
+the full model of discrete spin dynamics on a two-dimensional hexagonal lattice
+used in experiments with chromium trichloride. We prove its convergence to the
+continuum Landau-Lifshitz-Gilbert equation in the weak sense, despite
+difficulties arising from the absence of central symmetry when constructing
+difference quotient and interpolation operators on hexagonal lattices. To
+overcome these challenges, we introduce multi-step difference quotient and
+interpolation operators that possess an isometric property as a generalization
+of Ladysenskaya's interpolation operator. This result not only establishes a
+precise connection between parameters in atomistic models and those in
+continuum models but also provides necessary tools for analyzing weak
+convergence in other nonlinear problems on hexagonal lattices at microscopic
+and macroscopic scales seamlessly.",2306.06958v1
+2023-06-23,Molecular Insights into Chemical Reactions at Aqueous Aerosol Interfaces,"Atmospheric aerosols facilitate reactions between ambient gases and dissolved
+species. Here, we review our efforts to interrogate the uptake of these gases
+and the mechanisms of their reactions both theoretically and experimentally. We
+highlight the fascinating behavior of $\mathrm{N}_2\mathrm{O}_5$ in solutions
+ranging from pure water to complex mixtures, chosen because its
+aerosol-mediated reactions significantly impact global ozone, hydroxyl, and
+methane concentrations. As a hydrophobic, weakly soluble, and highly reactive
+species, $\mathrm{N}_2\mathrm{O}_5$ is a sensitive probe of the chemical and
+physical properties of aerosol interfaces. We employ contemporary theory to
+disentangle the fate of $\mathrm{N}_2\mathrm{O}_5$ as it approaches pure and
+salty water, starting with adsorption and ending with hydrolysis to HNO$_3$,
+chlorination to $\mathrm{ClNO}_2$, or evaporation. Flow reactor and gas-liquid
+scattering experiments probe even greater complexity as added ions, organic
+molecules, and surfactants alter interfacial composition and reaction rates.
+Together, we reveal a new perspective on multiphase chemistry in the
+atmosphere.",2306.13811v1
+2023-07-09,DIFF-NST: Diffusion Interleaving For deFormable Neural Style Transfer,"Neural Style Transfer (NST) is the field of study applying neural techniques
+to modify the artistic appearance of a content image to match the style of a
+reference style image. Traditionally, NST methods have focused on texture-based
+image edits, affecting mostly low level information and keeping most image
+structures the same. However, style-based deformation of the content is
+desirable for some styles, especially in cases where the style is abstract or
+the primary concept of the style is in its deformed rendition of some content.
+With the recent introduction of diffusion models, such as Stable Diffusion, we
+can access far more powerful image generation techniques, enabling new
+possibilities. In our work, we propose using this new class of models to
+perform style transfer while enabling deformable style transfer, an elusive
+capability in previous models. We show how leveraging the priors of these
+models can expose new artistic controls at inference time, and we document our
+findings in exploring this new direction for the field of style transfer.",2307.04157v2
+2023-07-11,Charge conservation in spin torque oscillators leads to a self-induced torque,"Spin torque oscillators are conventionally described by the
+Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation. However, at the onset of
+oscillations, the predictions of the conventional LLGS equation differ
+qualitatively from experimental results and thus appear to be incomplete. In
+this work we show that taking charge conservation into account leads to a
+previously-overlooked self-induced torque, which modifies the LLGS equation. We
+show that the self-induced torque originates from the pumping current that a
+precessing magnetization drives through a magnetic tunnel junction. To
+illustrate the importance of the self-induced torque, we consider an in-plane
+magnetized nanopillar, where it gives clear qualitative corrections to the
+conventional LLGS description.",2307.05105v3
+2023-07-13,Magnon-magnon coupling in synthetic ferrimagnets,"Magnetic multilayers with interlayer exchange coupling have been widely
+studied for both static and dynamic regimes. Their dynamical responses depend
+on the exchange coupling strength and magnetic properties of individual layers.
+Magnetic resonance spectra in such systems are conveniently discussed in terms
+of coupling of acoustic and optical modes. At a certain value of applied
+magnetic field, the two modes come close to being degenerate and the spectral
+gap indicates the strength of mode hybridisation. In this work, we
+theoretically and experimentally study the mode hybridisation of
+interlayer-exchange-coupled moments with dissimilar magnetisation and thickness
+of two ferromagnetic layers. In agreement with symmetry analysis for
+eigenmodes, our low-symmetry multilayers exhibit sizable spectral gaps for all
+experimental conditions. The spectra agree well with the predictions from the
+Landau-Lifshitz-Gilbert equation at the macrospin limit whose parameters are
+independently fixed by static measurements.",2307.06888v2
+2023-07-14,Mod $\ell$ gamma factors and a converse theorem for finite general linear groups,"For $q$ a power of a prime $p$, we study gamma factors of representations of
+$GL_n(\mathbb{F}_q)$ over an algebraically closed field $k$ of positive
+characteristic $\ell \neq p$. We show that the reduction mod $\ell$ of the
+gamma factor defined in characteristic zero fails to satisfy the analogue of
+the local converse theorem of Piatetski-Shapiro. To remedy this, we construct
+gamma factors valued in arbitrary $\mathbb{Z}[1/p, \zeta_p]$-algebras $A$,
+where $\zeta_p$ is a primitive $p$-th root of unity, for Whittaker-type
+representations $\rho$ and $\pi$ of $GL_n(\mathbb{F}_q)$ and
+$GL_m(\mathbb{F}_q)$ over $A$. We let $P(\pi)$ be the projective envelope of
+$\pi$ and let $R(\pi)$ be its endomorphism ring and define new gamma factors
+$\widetilde\gamma(\rho \times \pi) = \gamma((\rho\otimes_kR(\pi)) \times
+P(\pi))$, which take values in the local Artinian $k$-algebra $R(\pi)$. We
+prove a converse theorem for cuspidal representations using the new gamma
+factors. When $n=2$ and $m=1$ we construct a different ``new'' gamma factor
+$\gamma^{\ell}(\rho,\pi)$, which takes values in $k$ and satisfies a converse
+theorem.",2307.07593v1
+2023-07-20,Pathwise central limit theorem and moderate deviations via rough paths for SPDEs with multiplicative noise,"We put forward a general framework for the study of a pathwise central limit
+theorem (CLT) and a moderate deviation principle (MDP) for stochastic partial
+differential equations perturbed with a small multiplicative linear noise by
+means of the theory of rough paths. The CLT can be interpreted as the
+convergence to a pathwise derivative of the It\^o-Lyons map. The result follows
+by applying a pathwise Malliavin-like calculus for rough paths and from
+compactness methods. The convergence in the CLT is quantified by an optimal
+speed of convergence. From the exponential equivalence principle and the
+knowledge of the speed of convergence, we can derive easily a MDP. In
+particular, we do not apply the weak convergence approach usually employed in
+this framework. We derive a pathwise CLT and a MDP for the stochastic
+Landau-Lifschitz-Gilbert equation in one dimension, for the heat equation and
+for a stochastic reaction-diffusion equation. As a further application, we
+derive a pathwise convergence to the CLT limit and a corresponding MDP for
+equations driven by linear It\^o noise.",2307.10965v1
+2023-07-26,Learning sources of variability from high-dimensional observational studies,"Causal inference studies whether the presence of a variable influences an
+observed outcome. As measured by quantities such as the ""average treatment
+effect,"" this paradigm is employed across numerous biological fields, from
+vaccine and drug development to policy interventions. Unfortunately, the
+majority of these methods are often limited to univariate outcomes. Our work
+generalizes causal estimands to outcomes with any number of dimensions or any
+measurable space, and formulates traditional causal estimands for nominal
+variables as causal discrepancy tests. We propose a simple technique for
+adjusting universally consistent conditional independence tests and prove that
+these tests are universally consistent causal discrepancy tests. Numerical
+experiments illustrate that our method, Causal CDcorr, leads to improvements in
+both finite sample validity and power when compared to existing strategies. Our
+methods are all open source and available at github.com/ebridge2/cdcorr.",2307.13868v2
+2023-07-26,An Asynchronous and Low-Power True Random Number Generator using STT-MTJ,"The emerging Spin Transfer Torque Magnetic Tunnel Junction (STT-MTJ)
+technology exhibits interesting stochastic behavior combined with small area
+and low operation energy. It is, therefore, a promising technology for security
+applications, specifically the generation of random numbers. In this paper,
+STT-MTJ is used to construct an asynchronous true random number generator
+(TRNG) with low power and a high entropy rate. The asynchronous design enables
+decoupling of the random number generation from the system clock, allowing it
+to be embedded in low-power devices. The proposed TRNG is evaluated by a
+numerical simulation, using the Landau-Lifshitz-Gilbert (LLG) equation as the
+model of the STT-MTJ devices. Design considerations, attack analysis, and
+process variation are discussed and evaluated. We show that our design is
+robust to process variation, achieving an entropy generating rate between
+99.7Mbps and 127.8Mbps with 6-7.7 pJ per bit for 90% of the instances.",2307.14476v1
+2023-07-31,Evidence of Pseudogravitational Distortions of the Fermi Surface Geometry in the Antiferromagnetic Metal FeRh,"The confluence between high-energy physics and condensed matter has produced
+groundbreaking results via unexpected connections between the two traditionally
+disparate areas. In this work, we elucidate additional connectivity between
+high-energy and condensed matter physics by examining the interplay between
+spin-orbit interactions and local symmetry-breaking magnetic order in the
+magnetotransport of thin-film magnetic semimetal FeRh. We show that the change
+in sign of the normalized longitudinal magnetoresistance observed as a function
+of increasing in-plane magnetic field results from changes in the Fermi surface
+morphology. We demonstrate that the geometric distortions in the Fermi surface
+morphology are more clearly understood via the presence of pseudogravitational
+fields in the low-energy theory. The pseudogravitational connection provides
+additional insights into the origins of a ubiquitous phenomenon observed in
+many common magnetic materials and points to an alternative methodology for
+understanding phenomena in locally-ordered materials with strong spin-orbit
+interactions.",2308.00192v1
+2023-08-02,MammoDG: Generalisable Deep Learning Breaks the Limits of Cross-Domain Multi-Center Breast Cancer Screening,"Breast cancer is a major cause of cancer death among women, emphasising the
+importance of early detection for improved treatment outcomes and quality of
+life. Mammography, the primary diagnostic imaging test, poses challenges due to
+the high variability and patterns in mammograms. Double reading of mammograms
+is recommended in many screening programs to improve diagnostic accuracy but
+increases radiologists' workload. Researchers explore Machine Learning models
+to support expert decision-making. Stand-alone models have shown comparable or
+superior performance to radiologists, but some studies note decreased
+sensitivity with multiple datasets, indicating the need for high generalisation
+and robustness models. This work devises MammoDG, a novel deep-learning
+framework for generalisable and reliable analysis of cross-domain multi-center
+mammography data. MammoDG leverages multi-view mammograms and a novel
+contrastive mechanism to enhance generalisation capabilities. Extensive
+validation demonstrates MammoDG's superiority, highlighting the critical
+importance of domain generalisation for trustworthy mammography analysis in
+imaging protocol variations.",2308.01057v1
+2023-08-02,Sphaleron rate of $N_f=2+1$ QCD,"We compute the sphaleron rate of $N_f=2+1$ QCD at the physical point for a
+range of temperatures $200$ MeV $\lesssim T \lesssim 600$ MeV. We adopt a
+strategy recently applied in the quenched case, based on the extraction of the
+rate via a modified version of the Backus-Gilbert method from
+finite-lattice-spacing and finite-smoothing-radius Euclidean topological charge
+density correlators. The physical sphaleron rate is finally computed by
+performing a continuum limit at fixed physical smoothing radius, followed by a
+zero-smoothing extrapolation. Dynamical fermions were discretized using the
+staggered formulation, which is known to yield large lattice artifacts for the
+topological susceptibility. However, we find them to be rather mild for the
+sphaleron rate.",2308.01287v3
+2023-07-07,AI and the EU Digital Markets Act: Addressing the Risks of Bigness in Generative AI,"As AI technology advances rapidly, concerns over the risks of bigness in
+digital markets are also growing. The EU's Digital Markets Act (DMA) aims to
+address these risks. Still, the current framework may not adequately cover
+generative AI systems that could become gateways for AI-based services. This
+paper argues for integrating certain AI software as core platform services and
+classifying certain developers as gatekeepers under the DMA. We also propose an
+assessment of gatekeeper obligations to ensure they cover generative AI
+services. As the EU considers generative AI-specific rules and possible DMA
+amendments, this paper provides insights towards diversity and openness in
+generative AI services.",2308.02033v1
+2023-08-04,"Federated Learning: Organizational Opportunities, Challenges, and Adoption Strategies","Restrictive rules for data sharing in many industries have led to the
+development of federated learning. Federated learning is a machine-learning
+technique that allows distributed clients to train models collaboratively
+without the need to share their respective training data with others. In this
+paper, we first explore the technical foundations of federated learning and its
+organizational opportunities. Second, we present a conceptual framework for the
+adoption of federated learning, mapping four types of organizations by their
+artificial intelligence capabilities and limits to data sharing. We then
+discuss why exemplary organizations in different contexts - including public
+authorities, financial service providers, manufacturing companies, as well as
+research and development consortia - might consider different approaches to
+federated learning. To conclude, we argue that federated learning presents
+organizational challenges with ample interdisciplinary opportunities for
+information systems researchers.",2308.02219v2
+2023-08-04,Algorithm for evaluating distance-based entanglement measures,"Quantifying entanglement in quantum systems is an important yet challenging
+task due to its NP-hard nature. In this work, we propose an efficient algorithm
+for evaluating distance-based entanglement measures. Our approach builds on
+Gilbert's algorithm for convex optimization, providing a reliable upper bound
+on the entanglement of a given arbitrary state. We demonstrate the
+effectiveness of our algorithm by applying it to various examples, such as
+calculating the squared Bures metric of entanglement as well as the relative
+entropy of entanglement for GHZ states, $W$ states, Horodecki states, and
+chessboard states. These results demonstrate that our algorithm is a versatile
+and accurate tool that can quickly provide reliable upper bounds for
+entanglement measures.",2308.02326v1
+2023-08-07,Robust Ordinal Regression for Subsets Comparisons with Interactions,"This paper is dedicated to a robust ordinal method for learning the
+preferences of a decision maker between subsets. The decision model, derived
+from Fishburn and LaValle (1996) and whose parameters we learn, is general
+enough to be compatible with any strict weak order on subsets, thanks to the
+consideration of possible interactions between elements. Moreover, we accept
+not to predict some preferences if the available preference data are not
+compatible with a reliable prediction. A predicted preference is considered
+reliable if all the simplest models (Occam's razor) explaining the preference
+data agree on it. Following the robust ordinal regression methodology, our
+predictions are based on an uncertainty set encompassing the possible values of
+the model parameters. We define a robust ordinal dominance relation between
+subsets and we design a procedure to determine whether this dominance relation
+holds. Numerical tests are provided on synthetic and real-world data to
+evaluate the richness and reliability of the preference predictions made.",2308.03376v1
+2023-08-07,Strong Byzantine Agreement with Adaptive Word Complexity,"The strong Byzantine agreement (SBA) problem is defined among n processes,
+out of which t < n can be faulty and behave arbitrarily. SBA allows correct
+(non-faulty) processes to agree on a common value. Moreover, if all correct
+processes have proposed the same value, only that value can be agreed upon. It
+has been known for a long time that any solution to the SBA problem incurs
+quadratic worst-case word complexity; additionally, the bound was known to be
+tight. However, no existing protocol achieves adaptive word complexity, where
+the number of exchanged words depends on the actual number of faults, and not
+on the upper bound. Therefore, it is still unknown whether SBA with adaptive
+word complexity exists. This paper answers the question in the affirmative.
+Namely, we introduce STRONG, a synchronous protocol that solves SBA among n =
+(2 + Omega(1))t + 1 processes and achieves adaptive word complexity. We show
+that the fundamental challenge of adaptive SBA lies in efficiently solving
+certification, the problem of obtaining a constant-sized, locally-verifiable
+proof that a value can safely be decided.",2308.03524v1
+2023-08-24,Methods for transverse and longitudinal spin-photon coupling in silicon quantum dots with intrinsic spin-orbit effect,"In a full-scale quantum computer with a fault-tolerant architecture, having
+scalable, long-range interaction between qubits is expected to be a highly
+valuable resource. One promising method of achieving this is through the
+light-matter interaction between spins in semiconductors and photons in
+superconducting cavities. This paper examines the theory of both transverse and
+longitudinal spin-photon coupling and their applications in the silicon
+metal-oxide-semiconductor (SiMOS) platform. We propose a method of coupling
+which uses the intrinsic spin-orbit interaction arising from orbital
+degeneracies in SiMOS qubits. Using theoretical analysis and experimental data,
+we show that the strong coupling regime is achievable in the transverse scheme.
+We also evaluate the feasibility of a longitudinal coupling driven by an AC
+modulation on the qubit. These coupling methods eschew the requirement for an
+external micromagnet, enhancing prospects for scalability and integration into
+a large-scale quantum computer.",2308.12626v1
+2023-08-24,Object level footprint uncertainty quantification in infrastructure based sensing,"We examine the problem of estimating footprint uncertainty of objects imaged
+using the infrastructure based camera sensing. A closed form relationship is
+established between the ground coordinates and the sources of the camera
+errors. Using the error propagation equation, the covariance of a given ground
+coordinate can be measured as a function of the camera errors. The uncertainty
+of the footprint of the bounding box can then be given as the function of all
+the extreme points of the object footprint. In order to calculate the
+uncertainty of a ground point, the typical error sizes of the error sources are
+required. We present a method of estimating the typical error sizes from an
+experiment using a static, high-precision LiDAR as the ground truth. Finally,
+we present a simulated case study of uncertainty quantification from
+infrastructure based camera in CARLA to provide a sense of how the uncertainty
+changes across a left turn maneuver.",2308.12846v1
+2023-08-28,Data fusion using weakly aligned sources,"We introduce a new data fusion method that utilizes multiple data sources to
+estimate a smooth, finite-dimensional parameter. Most existing methods only
+make use of fully aligned data sources that share common conditional
+distributions of one or more variables of interest. However, in many settings,
+the scarcity of fully aligned sources can make existing methods require unduly
+large sample sizes to be useful. Our approach enables the incorporation of
+weakly aligned data sources that are not perfectly aligned, provided their
+degree of misalignment can be characterized by a prespecified density ratio
+model. We describe gains in efficiency and provide a general means to construct
+estimators achieving these gains. We illustrate our results by fusing data from
+two harmonized HIV monoclonal antibody prevention efficacy trials to study how
+a neutralizing antibody biomarker associates with HIV genotype.",2308.14836v1
+2023-08-31,Bi-level iterative regularization for inverse problems in nonlinear PDEs,"We investigate the ill-posed inverse problem of recovering unknown spatially
+dependent parameters in nonlinear evolution PDEs. We propose a bi-level
+Landweber scheme, where the upper-level parameter reconstruction embeds a
+lower-level state approximation. This can be seen as combining the classical
+reduced setting and the newer all-at-once setting, allowing us to,
+respectively, utilize well-posedness of the parameter-to-state map, and to
+bypass having to solve nonlinear PDEs exactly. Using this, we derive stopping
+rules for lower- and upper-level iterations and convergence of the bi-level
+method. We discuss application to parameter identification for the
+Landau-Lifshitz-Gilbert equation in magnetic particle imaging.",2308.16617v2
+2023-09-03,On Galois self-orthogonal algebraic geometry codes,"Galois self-orthogonal (SO) codes are generalizations of Euclidean and
+Hermitian SO codes. Algebraic geometry (AG) codes are the first known class of
+linear codes exceeding the Gilbert-Varshamov bound. Both of them have attracted
+much attention for their rich algebraic structures and wide applications in
+these years. In this paper, we consider them together and study Galois SO AG
+codes. A criterion for an AG code being Galois SO is presented. Based on this
+criterion, we construct several new classes of maximum distance separable (MDS)
+Galois SO AG codes from projective lines and several new classes of Galois SO
+AG codes from projective elliptic curves, hyper-elliptic curves and hermitian
+curves. In addition, we give an embedding method that allows us to obtain more
+MDS Galois SO codes from known MDS Galois SO AG codes.",2309.01051v2
+2023-09-17,Unleashing Quantum Simulation Advantages: Hamiltonian Subspace Encoding for Resource Efficient Quantum Simulations,"Number-conserved subspace encoding for fermionic Hamiltonians, which
+exponentially reduces qubit cost, is necessary for quantum advantages in
+variational quantum eigensolver (VQE). However, optimizing the trade-off
+between qubit compression and increased measurement cost poses a challenge. By
+employing the Gilbert-Varshamov bound on linear code, we optimize qubit scaling
+$\mathcal{O}(N\log_2M)$ and measurement cost $\mathcal{O}(M^4)$ for $M$ modes
+$N$ electrons chemistry problems. The compression is implemented with the
+Randomized Linear Encoding (RLE) algorithm on VQE for $\text{H}_2$ and LiH in
+the 6-31G* and STO-3G/6-31G* basis respectively. The resulting subspace circuit
+expressivity and trainability are enhanced with less circuit depth and higher
+noise tolerance.",2309.09370v1
+2023-09-20,Dimensions of splines of degree two,"Splines are defined as piecewise polynomials on the faces of a polyhedral
+complex that agree on the intersections of two faces. Splines are used in
+approximation theory and numerical analysis, with applications in data
+interpolation, to create smooth curves in computer graphics and to find
+numerical solutions to partial differential equations. Gilbert, Tymoczko, and
+Viel generalized the classical splines combinatorially and algebraically: a
+generalized spline is a vertex labeling of a graph $G$ by elements of the ring
+so that the difference between the labels of any two adjacent vertices lies in
+the ideal generated by the corresponding edge label. We study the generalized
+splines on the planar graphs whose edges are labeled by two-variable
+polynomials of the form $(ax+by+c)^2$ and whose vertices are labeled by
+polynomials of degree at most two. In this paper we address the upper-bound
+conjecture for the dimension of degree-2 splines of smoothness 1 when the edge
+labels are generic. The dimension is expressed in terms of the rank of the
+extended cycle basis matrix. We also provide a combinatorial algorithm on
+graphs to compute the rank.",2309.11650v1
+2023-09-25,DECORAIT -- DECentralized Opt-in/out Registry for AI Training,"We present DECORAIT; a decentralized registry through which content creators
+may assert their right to opt in or out of AI training as well as receive
+reward for their contributions. Generative AI (GenAI) enables images to be
+synthesized using AI models trained on vast amounts of data scraped from public
+sources. Model and content creators who may wish to share their work openly
+without sanctioning its use for training are thus presented with a data
+governance challenge. Further, establishing the provenance of GenAI training
+data is important to creatives to ensure fair recognition and reward for their
+such use. We report a prototype of DECORAIT, which explores hierarchical
+clustering and a combination of on/off-chain storage to create a scalable
+decentralized registry to trace the provenance of GenAI training data in order
+to determine training consent and reward creatives who contribute that data.
+DECORAIT combines distributed ledger technology (DLT) with visual
+fingerprinting, leveraging the emerging C2PA (Coalition for Content Provenance
+and Authenticity) standard to create a secure, open registry through which
+creatives may express consent and data ownership for GenAI.",2309.14400v1
+2023-10-05,Multi-Resolution Audio-Visual Feature Fusion for Temporal Action Localization,"Temporal Action Localization (TAL) aims to identify actions' start, end, and
+class labels in untrimmed videos. While recent advancements using transformer
+networks and Feature Pyramid Networks (FPN) have enhanced visual feature
+recognition in TAL tasks, less progress has been made in the integration of
+audio features into such frameworks. This paper introduces the Multi-Resolution
+Audio-Visual Feature Fusion (MRAV-FF), an innovative method to merge
+audio-visual data across different temporal resolutions. Central to our
+approach is a hierarchical gated cross-attention mechanism, which discerningly
+weighs the importance of audio information at diverse temporal scales. Such a
+technique not only refines the precision of regression boundaries but also
+bolsters classification confidence. Importantly, MRAV-FF is versatile, making
+it compatible with existing FPN TAL architectures and offering a significant
+enhancement in performance when audio data is available.",2310.03456v1
+2023-10-20,The History and Risks of Reinforcement Learning and Human Feedback,"Reinforcement learning from human feedback (RLHF) has emerged as a powerful
+technique to make large language models (LLMs) easier to use and more
+effective. A core piece of the RLHF process is the training and utilization of
+a model of human preferences that acts as a reward function for optimization.
+This approach, which operates at the intersection of many stakeholders and
+academic disciplines, remains poorly understood. RLHF reward models are often
+cited as being central to achieving performance, yet very few descriptors of
+capabilities, evaluations, training methods, or open-source models exist. Given
+this lack of information, further study and transparency is needed for learned
+RLHF reward models. In this paper, we illustrate the complex history of
+optimizing preferences, and articulate lines of inquiry to understand the
+sociotechnical context of reward models. In particular, we highlight the
+ontological differences between costs, rewards, and preferences at stake in
+RLHF's foundations, related methodological tensions, and possible research
+directions to improve general understanding of how reward models function.",2310.13595v2
+2023-11-24,The quenched glueball spectrum from smeared spectral densities,"The standard approach to compute the glueball spectrum on the lattice relies
+on the evaluation of effective masses from two-point correlation functions of
+operators with the quantum numbers of the desired state. In this work, we
+propose an alternative procedure, based on the numerical computation of smeared
+spectral densities. Even though the extraction of the latter from lattice
+correlators is a notoriously ill-posed inverse problem, we show that a recently
+developed numerical method, based on the Backus-Gilbert regularization,
+provides a robust way to evaluate a smeared version of the spectral densities.
+Fitting the latter to a combination of Gaussians, we extract the masses of the
+lightest glueball and of its first excitation in the spectrum of the theory.
+While the preliminary results presented in this contribution are restricted to
+simulations at finite lattice spacing and finite volume, and for the purely
+gluonic sector of QCD, they represent the first step in a systematic
+investigation of glueballs using spectral-reconstruction methods.",2311.14806v1
+2023-11-28,Data-efficient operator learning for solving high Mach number fluid flow problems,"We consider the problem of using SciML to predict solutions of high Mach
+fluid flows over irregular geometries. In this setting, data is limited, and so
+it is desirable for models to perform well in the low-data setting. We show
+that Neural Basis Functions (NBF), which learns a basis of behavior modes from
+the data and then uses this basis to make predictions, is more effective than a
+basis-unaware baseline model. In addition, we identify continuing challenges in
+the space of predicting solutions for this type of problem.",2311.16860v2
+2023-11-30,ZeST-NeRF: Using temporal aggregation for Zero-Shot Temporal NeRFs,"In the field of media production, video editing techniques play a pivotal
+role. Recent approaches have had great success at performing novel view image
+synthesis of static scenes. But adding temporal information adds an extra layer
+of complexity. Previous models have focused on implicitly representing static
+and dynamic scenes using NeRF. These models achieve impressive results but are
+costly at training and inference time. They overfit an MLP to describe the
+scene implicitly as a function of position. This paper proposes ZeST-NeRF, a
+new approach that can produce temporal NeRFs for new scenes without retraining.
+We can accurately reconstruct novel views using multi-view synthesis techniques
+and scene flow-field estimation, trained only with unrelated scenes. We
+demonstrate how existing state-of-the-art approaches from a range of fields
+cannot adequately solve this new task and demonstrate the efficacy of our
+solution. The resulting network improves quantitatively by 15% and produces
+significantly better visual results.",2311.18491v1
+2023-12-05,ViscoNet: Bridging and Harmonizing Visual and Textual Conditioning for ControlNet,"This paper introduces ViscoNet, a novel method that enhances text-to-image
+human generation models with visual prompting. Unlike existing methods that
+rely on lengthy text descriptions to control the image structure, ViscoNet
+allows users to specify the visual appearance of the target object with a
+reference image. ViscoNet disentangles the object's appearance from the image
+background and injects it into a pre-trained latent diffusion model (LDM) model
+via a ControlNet branch. This way, ViscoNet mitigates the style mode collapse
+problem and enables precise and flexible visual control. We demonstrate the
+effectiveness of ViscoNet on human image generation, where it can manipulate
+visual attributes and artistic styles with text and image prompts. We also show
+that ViscoNet can learn visual conditioning from small and specific object
+domains while preserving the generative power of the LDM backbone.",2312.03154v1
+2023-12-08,Convergent finite element methods for antiferromagnetic and ferrimagnetic materials,"We consider the numerical approximation of a continuum model of
+antiferromagnetic and ferrimagnetic materials. The state of the material is
+described in terms of two unit-length vector fields, which can be interpreted
+as the magnetizations averaging the spins of two sublattices. For the static
+setting, which requires the solution of a constrained energy minimization
+problem, we introduce a discretization based on first-order finite elements and
+prove its $\Gamma$-convergence. Then, we propose and analyze two iterative
+algorithms for the computation of low-energy stationary points. The algorithms
+are obtained from (semi-)implicit time discretizations of gradient flows of the
+energy. Finally, we extend the algorithms to the dynamic setting, which
+consists of a nonlinear system of two Landau-Lifshitz-Gilbert equations solved
+by the two fields, and we prove unconditional stability and convergence of the
+finite element approximations toward a weak solution of the problem. Numerical
+experiments assess the performance of the algorithms and demonstrate their
+applicability for the simulation of physical processes involving
+antiferromagnetic and ferrimagnetic materials.",2312.04939v1
+2023-12-18,Modelling the 3D spatiotemporal organisation of chromatin replication,"We propose a polymer model for the dynamics of chromatin replication in three
+dimensional space. Our simulations indicate that both immobile and tracking
+replisomes may self-assemble during the process, reconciling previous
+apparently discordant experimental evidence in favour of either scenario. Which
+of the two morphologies appears in our model depends on the balance between
+non-specific and origin-targeting interactions between chromatin and firing
+factors -- polymerases and other components of the replisome. Non-specific
+interactions are also necessary to yield clustering of factors and replication
+forks, creating structures akin to the replication foci observed in mammalian
+cells in vivo. We suggest that cluster formation provides an underappreciated
+but robust pathway to avoid stalled or faulty forks, which would otherwise
+diminish the efficiency of the replication process. Additionally, our
+simulations allow us to predict different modes of cluster growth during
+S-phase, which could be tested experimentally, and they show that the three
+dimensional chromatin context is important to understand replication patterns
+in fission yeast.",2312.11275v1
+2024-01-09,Revealing dark exciton signatures in polariton spectra of 2D materials,"Dark excitons in transition metal dichalcogenides (TMD) have been so far
+neglected in the context of polariton physics due to their lack of oscillator
+strength. However, in tungsten-based TMDs, dark excitons are known to be the
+energetically lowest states and could thus provide important scattering
+partners for polaritons. In this joint theory-experiment work, we investigate
+the impact of the full exciton energy landscape on polariton absorption and
+reflectance. By changing the cavity detuning, we vary the polariton energy
+relative to the unaffected dark excitons in such a way that we open or close
+specific phonon-driven scattering channels. We demonstrate both in theory and
+experiment that this controlled switching of scattering channels manifests in
+characteristic sharp changes in optical spectra of polaritons. These spectral
+features can be exploited to extract the position of dark excitons. Our work
+suggests new possibilities for exploiting polaritons for fingerprinting
+nanomaterials via their unique exciton landscape.",2401.04588v1
+2024-01-10,Electrical Non-Hermitian Control of Topological Magnon Spin Transport,"Magnonic topological phases realize chiral edge spin waves that are protected
+against backscattering, potentially enabling highly efficient spin transport.
+Here we show that the spin transport through these magnonic chiral edge states
+can be electrically manipulated by non-Hermitian control. We consider the
+paradigmatic magnon Haldane model and show that it is transformed into an
+effective non-Hermitian magnon Chern insulator by including a
+sublattice-dependent spin-orbit torque. In linear spin-wave theory, this
+electrically induced torque causes a lasing of the chiral edge magnons along
+certain edge directions, leading to an enhancement of the spin-wave amplitude.
+This prediction is confirmed by numerical simulations based on the
+Landau-Lifshitz-Gilbert equation. For a spin-wave transport setup, in which
+magnons are excited by a microwave field and detected with a normal metal
+conductor, we find that the magnon amplification is remarkably robust against
+disorder, establishing non-Hermitian control as a promising avenue for
+topological magnonics.",2401.04967v2
+2024-01-24,The Dynamics of (Not) Unfollowing Misinformation Spreaders,"Many studies explore how people 'come into' misinformation exposure. But much
+less is known about how people 'come out of' misinformation exposure. Do people
+organically sever ties to misinformation spreaders? And what predicts doing so?
+Over six months, we tracked the frequency and predictors of ~900K followers
+unfollowing ~5K health misinformation spreaders on Twitter. We found that
+misinformation ties are persistent. Monthly unfollowing rates are just 0.52%.
+In other words, 99.5% of misinformation ties persist each month. Users are also
+31% more likely to unfollow non-misinformation spreaders than they are to
+unfollow misinformation spreaders. Although generally infrequent, the factors
+most associated with unfollowing misinformation spreaders are (1) redundancy
+and (2) ideology. First, users initially following many spreaders, or who
+follow spreaders that tweet often, are most likely to unfollow later. Second,
+liberals are more likely to unfollow than conservatives. Overall, we observe a
+strong persistence of misinformation ties. The fact that users rarely unfollow
+misinformation spreaders suggests a need for external nudges and the importance
+of preventing exposure from arising in the first place.",2401.13480v2
+2024-01-29,FPGA Technology Mapping Using Sketch-Guided Program Synthesis,"FPGA technology mapping is the process of implementing a hardware design
+expressed in high-level HDL (hardware design language) code using the
+low-level, architecture-specific primitives of the target FPGA. As FPGAs become
+increasingly heterogeneous, achieving high performance requires hardware
+synthesis tools that better support mapping to complex, highly configurable
+primitives like digital signal processors (DSPs). Current tools support DSP
+mapping via handwritten special-case mapping rules, which are laborious to
+write, error-prone, and often overlook mapping opportunities. We introduce
+Lakeroad, a principled approach to technology mapping via sketch-guided program
+synthesis. Lakeroad leverages two techniques -- architecture-independent sketch
+templates and semantics extraction from HDL -- to provide extensible technology
+mapping with stronger correctness guarantees and higher coverage of mapping
+opportunities than state-of-the-art tools. Across representative
+microbenchmarks, Lakeroad produces 2--3.5$\times$ the number of optimal
+mappings compared to proprietary state-of-the-art tools and 6--44$\times$ the
+number of optimal mappings compared to popular open-source tools, while also
+providing correctness guarantees not given by any other tool.",2401.16526v1
+2024-02-05,Cybersickness Detection through Head Movement Patterns: A Promising Approach,"Despite the widespread adoption of Virtual Reality (VR) technology,
+cybersickness remains a barrier for some users. This research investigates head
+movement patterns as a novel physiological marker for cybersickness detection.
+Unlike traditional markers, head movements provide a continuous, non-invasive
+measure that can be easily captured through the sensors embedded in all
+commercial VR headsets. We used a publicly available dataset from a VR
+experiment involving 75 participants and analyzed head movements across six
+axes. An extensive feature extraction process was then performed on the head
+movement dataset and its derivatives, including velocity, acceleration, and
+jerk. Three categories of features were extracted, encompassing statistical,
+temporal, and spectral features. Subsequently, we employed the Recursive
+Feature Elimination method to select the most important and effective features.
+In a series of experiments, we trained a variety of machine learning
+algorithms. The results demonstrate a 76% accuracy and 83% precision in
+predicting cybersickness in the subjects based on the head movements. This
+study contribution to the cybersickness literature lies in offering a
+preliminary analysis of a new source of data and providing insight into the
+relationship of head movements and cybersickness.",2402.02725v2
+2024-02-05,Bifurcation to complex dynamics in largely modulated voltage-controlled parametric oscillator,"An experimental demonstration of a parametric oscillation of a magnetization
+in a ferromagnet was performed recently by applying a microwave voltage,
+indicating the potential to be applied in a switching method in non-volatile
+memories. In the previous works, the modulation of a perpendicular magnetic
+anisotropy field produced by the microwave voltage was small compared with an
+external magnetic field pointing in an in-plane direction. A recent trend is,
+however, opposite, where an efficiency of the voltage controlled magnetic
+anisotropy (VCMA) effect is increased significantly by material research and
+thus, the modulated magnetic anisotropy field can be larger than the external
+magnetic field. Here, we solved the Landau-Lifshitz-Gilbert equation
+numerically and investigated the magnetization dynamics driven under a wide
+range of the microwave VCMA effect. We evaluated bifurcation diagrams, which
+summarize local maxima of the magnetization dynamics. For low modulation
+amplitudes, the local maximum is a single point because the dynamics is the
+periodic parametric oscillation. The bifurcation diagrams show distributions of
+the local maxima when the microwave magnetic anisotropy field becomes larger
+than the external magnetic field. The appearance of this broadened distribution
+indicates complex dynamics such as chaotic and transient-chaotic behaviors,
+which were confirmed from an analysis of temporal dynamics.",2402.02742v1
+2024-02-12,Gravitational Lensing of Galaxy Clustering,"We investigate lensing reconstruction using the clustered galaxy distribution
+as a source field, using both the traditional cosmic microwave background
+quadratic estimator and a shear-only estimator. We calculate the expected
+signal-to-noise ratio of the cross power spectrum of such reconstructions with
+cosmic shear measurements for an LSST-like galaxy survey. Modeling the galaxy
+field as a Gaussian random field, we find that there is substantial clustering
+signal in the source field at angular scales substantially smaller than those
+typically used by CMB reconstructions. The expected signal-to-noise for
+cross-correlations in LSST from cosmic shear is $\sim$60 in the presence of
+shape noise, while cross correlating with a sample-variance limited mass map
+would have signal-to-noise in the hundreds. This type of cross-correlation
+could be used as a way to identify systematic errors in lensing studies and is
+just one example of many possible higher order correlations in galaxy surveys
+that may contain substantial cosmological information.",2402.07988v1
+2024-03-05,Spintronic Implementation of UNet for Image Segmentation,"Image segmentation plays a crucial role in computer vision applications like
+self-driving cars, satellite imagery analysis, and medical diagnosis.
+Implementing these complex deep neural networks on conventional hardware is
+highly inefficient. In this work, we propose hardware implementation of UNet
+for segmentation tasks, using spintronic devices. Our approach involves
+designing hardware for convolution, deconvolution, ReLU, and max pooling layers
+of the UNet architecture. We demonstrate the synaptic behavior of the domain
+wall MTJ, and design convolution and deconvolution layers using the domain
+wall-based crossbar array. We utilize the orthogonal current injected MTJ with
+its continuous resistance change and showcase the ReLU and max pooling
+functions. We employ a hybrid simulation setup by coupling micromagnetic
+simulation, non-equilibrium Green's function,
+Landau-Lifshitz-Gilbert-Slonczewski equations, and circuit simulation with
+Python programming to incorporate the diverse physics of spin-transport,
+magnetization dynamics, and CMOS elements in our proposed designs. We evaluate
+our UNet design on the CamVid dataset and achieve segmentation accuracies that
+are comparable to software implementation. During training, our design consumes
+43.59pJ of energy for synaptic weight updates.",2403.02863v1
+2024-03-06,A Survey on Adversarial Contention Resolution,"Contention resolution addresses the challenge of coordinating access by
+multiple processes to a shared resource such as memory, disk storage, or a
+communication channel. Originally spurred by challenges in database systems and
+bus networks, contention resolution has endured as an important abstraction for
+resource sharing, despite decades of technological change. Here, we survey the
+literature on resolving worst-case contention, where the number of processes
+and the time at which each process may start seeking access to the resource is
+dictated by an adversary. We highlight the evolution of contention resolution,
+where new concerns -- such as security, quality of service, and energy
+efficiency -- are motivated by modern systems. These efforts have yielded
+insights into the limits of randomized and deterministic approaches, as well as
+the impact of different model assumptions such as global clock synchronization,
+knowledge of the number of processors, feedback from access attempts, and
+attacks on the availability of the shared resource.",2403.03876v1
+2024-03-01,Sketching the Heat Kernel: Using Gaussian Processes to Embed Data,"This paper introduces a novel, non-deterministic method for embedding data in
+low-dimensional Euclidean space based on computing realizations of a Gaussian
+process depending on the geometry of the data. This type of embedding first
+appeared in (Adler et al, 2018) as a theoretical model for a generic manifold
+in high dimensions.
+  In particular, we take the covariance function of the Gaussian process to be
+the heat kernel, and computing the embedding amounts to sketching a matrix
+representing the heat kernel. The Karhunen-Lo\`eve expansion reveals that the
+straight-line distances in the embedding approximate the diffusion distance in
+a probabilistic sense, avoiding the need for sharp cutoffs and maintaining some
+of the smaller-scale structure.
+  Our method demonstrates further advantage in its robustness to outliers. We
+justify the approach with both theory and experiments.",2403.07929v1
+2024-03-27,PLOT-TAL -- Prompt Learning with Optimal Transport for Few-Shot Temporal Action Localization,"This paper introduces a novel approach to temporal action localization (TAL)
+in few-shot learning. Our work addresses the inherent limitations of
+conventional single-prompt learning methods that often lead to overfitting due
+to the inability to generalize across varying contexts in real-world videos.
+Recognizing the diversity of camera views, backgrounds, and objects in videos,
+we propose a multi-prompt learning framework enhanced with optimal transport.
+This design allows the model to learn a set of diverse prompts for each action,
+capturing general characteristics more effectively and distributing the
+representation to mitigate the risk of overfitting. Furthermore, by employing
+optimal transport theory, we efficiently align these prompts with action
+features, optimizing for a comprehensive representation that adapts to the
+multifaceted nature of video data. Our experiments demonstrate significant
+improvements in action localization accuracy and robustness in few-shot
+settings on the standard challenging datasets of THUMOS-14 and EpicKitchens100,
+highlighting the efficacy of our multi-prompt optimal transport approach in
+overcoming the challenges of conventional few-shot TAL methods.",2403.18915v1
+2024-04-02,Exploring Spin Polarization of Heavy Quarks in Magnetic Fields and Hot Medium,"Relativistic heavy-ion collisions give rise to the formation of both
+deconfined QCD matter and a strong magnetic field. The spin of heavy quarks is
+influenced by interactions with the external magnetic field as well as by
+random scatterings with thermal light partons. The presence of QCD matter
+comprising charged quarks can extend the lifetime and strength of the magnetic
+field, thereby enhancing the degree of heavy quark polarization. However, the
+random scatterings with QCD matter tend to diminish heavy quark polarization.
+In this study, we utilize the Landau-Lifshitz-Gilbert (LLG) equation to
+investigate both these contributions. Taking into account the realistic
+evolutions of medium temperatures and the in-medium magnetic fields at the
+Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC), we
+observe that heavy quark polarization is limited by the short lifetime of the
+magnetic field and the high temperatures of the medium. Furthermore, we explore
+the mass dependence of quark polarization, revealing that the polarization
+degree of strange quarks is much larger than that of charm quarks.",2404.02032v1
+1996-05-06,A Keck HIRES Investigation of the Metal Abundances and Kinematics of Three Damped Lya Systems Toward Q2206-199,"We present high resolution, high SNR spectra of the QSO Q2206-199 obtained
+with HIRES on the 10m W.M. Keck Telescope. Our analysis focuses on the two
+previously identified damped \lya systems found at $z=1.920$ and $z=2.076$. For
+each system, we measure accurate abundances. The $z=1.920$ system exhibits the
+highest metallicity we have measured for a damped \lya system. We report the
+first confident ($>5 \sigma$) detection of Ti in a QSO absorption line system.
+By contrast the $z=2.076$ system is the most metal poor we have analyzed,
+showing absorption features for only the strongest transitions. We find no
+positive evidence for the presence of dust in either system. The two damped
+systems exhibit significantly different kinematic characteristics, yet we
+contend the two systems are consistent with one physical description: that of a
+thick, rotating disk.
+  We investigate a very strong Mg II system at $z=0.752$ which is very likely
+yet a third damped \lya system. The very weak Mn II and Ti II transitions have
+been positively measured and imply $\log \N{HI} > 19.0$. We analyze the
+abundance ratios [Mn/Fe] and [Ti/Fe] and their values are inconsistent with
+dust depletion, yet consistent with the abundance pattern detected for halo
+stars in the Galaxy (see Lu et al. 1996a).
+  Finally, we identify a C IV system at $z=2.014$ that shows a very narrow
+feature in Si IV and C IV absorption. The corresponding $b$ values (5.5 \kms
+and 8.9 \kms for Si IV and C IV) for this component suggest a temperature of
+$4.7 \sci{4} \rm K$. Because collisional ionization can explain the observed
+abundances only for $T > 8 \sci{4} \rm K$, we contend these ions must have
+formed through a different physical process (e.g. photoionization).",9605021v2
+1996-09-09,The Population of Damped Lyman-alpha and Lyman Limit Systems in the Cold Dark Matter Model,"Lyman limit and damped Lyman-alpha absorption systems probe the distribution
+of collapsed, cold gas at high redshift. Numerical simulations that incorporate
+gravity and gas dynamics can predict the abundance of such absorbers in
+cosmological models. We develop a semi-analytical method to correct the
+numerical predictions for the contribution of unresolved low mass halos, and we
+apply this method to the Katz et al. (1996) simulation of the standard cold
+dark matter model ($\Omega=1$, $h=0.5$, $\Omega_b=0.05$, $\sigma_8=0.7$). Using
+this simulation and higher resolution simulations of individual low mass
+systems, we determine the relation between a halo's circular velocity $v_c$ and
+its cross section for producing Lyman limit or damped absorption. We combine
+this relation with the Press-Schechter formula for the abundance of halos to
+compute the number of absorbers per unit redshift. The resolution correction
+increases the predicted abundances by about a factor of two at z=2, 3, and 4,
+bringing the predicted number of damped absorbers into quite good agreement
+with observations. Roughly half of the systems reside in halos with circular
+velocities $v_c>100\kms$ and half in halos with $35\kms<v_c<100\kms$. Halos
+with $v_c>150\kms$ typically harbor two or more systems capable of producing
+damped absorption. Even with the resolution correction, the predicted abundance
+of Lyman limit systems is a factor of three below observational estimates,
+signifying either a failure of standard CDM or a failure of these simulations
+to resolve the systems responsible for most Lyman limit absorption. By
+comparing simulations with and without star formation, we find that depletion
+of the gas supply by star formation affects absorption line statistics at
+$z>=2$ only for column densities exceeding $N_{HI}=10^{22} cm^{-2}$.",9609072v1
+1998-05-22,Protogalactic Disk Models of Damped Lya Kinematics,"We present new observational results on the kinematics of the damped lya
+systems. Our full sample is now comprised of 31 low-ion profiles and exhibits
+similar characteristics to the sample from Paper I. The primary exception is
+that the new distribution of velocity widths includes values out to a maximum
+of nearly 300 km/s, approx 100 km/s greater than the previous maximum. These
+high velocity width systems will significantly leverage models introduced to
+explain the damped lya systems. Comparing the characteristics from low-redshift
+and high-redshift sub-samples, we find no evidence for significant evolution in
+the kinematic properties of protogalaxies from z = 2.0 - 3.3.
+  The new observations give greater statistical significance to the main
+conclusions of our first paper. In particular, those models inconsistent with
+the damped lya observations in Paper I are ruled out at even higher levels of
+confidence. At the same time, the observations are consistent with a population
+of rapidly rotating, thick disks (the TRD model) at high redshift.
+  Buoyed by the success of the TRD model, we investigate it more closely by
+considering more realistic disk properties. Our goal is to demonstrate the
+statistical power of the damped lya observations by investigating the
+robustness of the TRD model. In particular, we study the effects of warping,
+realistic rotation curves, and photoionization on the kinematics of disks in
+the TRD model. The principal results are: (1) disk warping has only minimal
+effect on the kinematic results, primarily influencing the effective disk
+thickness, (2) the TRD model is robust to more realistic rotation curves; (3)
+the effects of photoionization require thicker disks to give consistent
+velocity width distributions. [abridged]",9805293v1
+2000-05-05,UVES observations of QSO 0000-2620: oxygen and zinc abundances in the Damped Ly-alpha galaxy at z_abs=3.3901,"Observations of the QSO 0000-2620 with UVES spectrograph at the 8.2m ESO
+KUEYEN telescope are used for abundance analysis of the damped Ly-alpha system
+at z_{abs}=3.3901. Several Oxygen lines are identified in the Ly_alpha forest
+and a measure for the oxygen abundance is obtained at [O/H]=-1.85 +/- 0.1 by
+means of the unsaturated OI 925 A and OI 950 A lines. This represents the most
+accurate O measurement in a damped Ly_alpha galaxy so far. We have also
+detected ZnII 2026 A and CrII 2056, 2062 A redshifted at about 8900 A and found
+abundances [Zn/H] = -2.07 +/- 0.1 and [Cr/H]=-1.99 +/- 0.1. Furthermore,
+previous measurements of Fe, Si, Ni and N have been refined yielding
+[Fe/H]=-2.04 +/- 0.1, [Si/H]=-1.90 +/- 0.1, [Ni/H]=-2.27 +/- 0.1, and
+[N/H]=-2.68 +/- 0.1. The abundance of the non-refractory element zinc is the
+lowest among the damped Ly-alpha systems showing that the associated
+intervening galaxy is indeed in the early stages of its chemical evolution. The
+fact that the Zn abundance is identical to that of the refractory elements Fe
+and Cr suggests that dust grains have not formed yet. In this Damped Ly-alpha
+system the observed [O,S,Si/Zn,Fe,Cr] ratios, in whatever combination are
+taken, are close to solar (i.e 0.1-0.2 dex) and do not show the
+[alpha-element/Fe] enhancement observed in Milky Way stars of comparable
+metallicity. The observed behavior supports a galaxy evolution model
+characterized by either episodic or low star formation rate rather than a
+Milky-Way-type evolutionary model.",0005098v1
+2002-02-06,The UCSD HIRES/KeckI Damped Lya Abundance Database III. An Empirical Study of Photoionization in the Damped Lya System Toward GB1759+7539,"We investigate the ionization state of the damped Lya system at z=2.62 toward
+GB1759+7539 through an analysis of ionic ratios sensitive to photoionization:
+ArI/SII, FeIII/FeII, NII/NI, AlIII/AlII. Approximately half of the metals arise
+in a mostly neutral velocity component with HI/H > 0.9, based on FeIII/FeII <
+0.013. In contrast, the remaining half exhibits FeIII/FeII~0.3 indicative of a
+partially ionized medium with HI/H~0.5. These conclusions are supported by the
+observed NII/NI, AlIII/AlII, and ArI/SII ratios.
+  We assess ionization corrections for the observed column densities through
+photoionization models derived from the CLOUDY software package. In the neutral
+gas, the ionization corrections are negligible except for ArI. However for the
+partially ionized gas, element abundance ratios differ from the ionic ratios by
+0.1-0.3 dex for (SiII, SII, NiII, AlII)/FeII ratios and more for (NI,
+ArI)/FeII. Independent of the shape of the photoionizing spectrum and
+assumptions on the number of ionization phases, these ionization corrections
+have minimal impact (<0.1dex) on the total metallicity inferred for this damped
+Lya system. Measurements on the relative elemental abundances of the partially
+ionized gas, however, have a greater than ~0.15 dex uncertainty which hides the
+effects of nucleosynthesis and dust depletion.
+  We caution the reader that this damped system is unusual for a number of
+reasons (e.g. a very low ArI/SII ratio) and we believe its ionization
+properties are special but not unique. Nevertheless, it clearly shows the value
+of examining photoionization diagnostics like FeIII/FeII in a larger sample of
+systems.",0202140v1
+2009-09-26,Damped and sub-damped Lyman-? absorbers in z > 4 QSOs,"We present the results of a survey for damped (DLA, log N(H I) > 20.3) and
+sub-damped Lyman-? systems (19.5 < log N(H I) < 20.3) at z > 2.55 along the
+lines-of-sight to 77 quasars with emission redshifts in the range 4 < zem <
+6.3. Intermediate resolution (R ? 4300) spectra have been obtained with the
+Echellette Spectrograph and Imager (ESI) mounted on the Keck telescope. A total
+of 100 systems with log N(H I) > 19.5 are detected of which 40 systems are
+damped Lyman-? systems for an absorption length of ?X = 378. About half of the
+lines of sight of this homogeneous survey have never been investigated for
+DLAs. We study the evolution with redshift of the cosmological density of the
+neutral gas and find, consis- tently with previous studies at similar
+resolution, that ?DLA,H I decreases at z > 3.5. The overall cosmological
+evolution of ?HI shows a peak around this redshift. The H I column density
+distribution for log N(H I) ? 20.3 is ?tted, consistently with previous
+surveys, with a single power-law of index ? ? -1.8$\pm$0.25. This power-law
+overpredicts data at the high-end and a second, much steeper, power-law (or a
+gamma function) is needed. There is a flattening of the function at lower H I
+column densities with an index of ? ? ?1.4 for the column density range log N(H
+I) = 19.5?21. The fraction of H I mass in sub-DLAs is of the order of 30%. The
+H column density distribution does not evolve strongly from z ? 2.5 to z ? 4.5.",0909.4839v2
+2009-10-28,Nonlinear envelope equation and nonlinear Landau damping rate for a driven electron plasma wave,"In this paper, we provide a theoretical description, and calculate, the
+nonlinear frequency shift, group velocity and collionless damping rate, $\nu$,
+of a driven electron plasma wave (EPW). All these quantities, whose physical
+content will be discussed, are identified as terms of an envelope equation
+allowing one to predict how efficiently an EPW may be externally driven. This
+envelope equation is derived directly from Gauss law and from the investigation
+of the nonlinear electron motion, provided that the time and space rates of
+variation of the EPW amplitude, $E_p$, are small compared to the plasma
+frequency or the inverse of the Debye length. $\nu$ arises within the EPW
+envelope equation as more complicated an operator than a plain damping rate,
+and may only be viewed as such because $(\nu E_p)/E_p$ remains nearly constant
+before abruptly dropping to zero. We provide a practical analytic formula for
+$\nu$ and show, without resorting to complex contour deformation, that in the
+limit $E_p \to 0$, $\nu$ is nothing but the Landau damping rate. We then term
+$\nu$ the ""nonlinear Landau damping rate"" of the driven plasma wave. As for the
+nonlinear frequency shift of the EPW, it is also derived theoretically and
+found to assume values significantly different from previously published ones,
+assuming that the wave is freely propagating. Moreover, we find no limitation
+in $k \lambda_D$, $k$ being the plasma wavenumber and $\lambda_D$ the Debye
+length, for a solution to the dispertion relation to exist, and want to stress
+here the importance of specifying how an EPW is generated to discuss its
+properties. Our theoretical predictions are in excellent agreement with results
+inferred from Vlasov simulations of stimulated Raman scattering (SRS), and an
+application of our theory to the study of SRS is presented.",0910.5289v1
+2011-05-19,"Tidal dissipation compared to seismic dissipation: in small bodies, in earths, and in superearths","While the seismic quality factor and phase lag are defined solely by the bulk
+properties of the mantle, their tidal counterparts are determined both by the
+bulk properties and self-gravitation of a body as a whole. For a qualitative
+estimate, we model the body with a homogeneous sphere and express the tidal
+phase lag through the lag in a sample of material. Although simplistic, our
+model is sufficient to understand that the lags are not identical. The
+difference emerges because self-gravitation pulls the tidal bulge down. At low
+frequencies, this reduces strain and makes tidal damping less efficient in
+larger bodies. At high frequencies, competition between self-gravitation and
+rheology becomes more complex, though for sufficiently large superearths the
+same rule works: the larger the body, the weaker tidal damping in it. Being
+negligible for small terrestrial planets and moons, the difference between the
+seismic and tidal lagging (and likewise between the seismic and tidal damping)
+becomes very considerable for superearths. In those, it is much lower than what
+one might expect from using a seismic quality factor. The tidal damping rate
+deviates from the seismic damping rate especially in the zero-frequency limit,
+and this difference takes place for bodies of any size. So the equal in
+magnitude but opposite in sign tidal torques, exerted on one another by the
+primary and the secondary, go smoothly through zero as the secondary crosses
+the synchronous orbit. We describe the mantle rheology with the Andrade model,
+allowing it to lean towards the Maxwell model at the lowest frequencies. To
+implement this additional flexibility, we reformulate the Andrade model by
+endowing it with a free parameter which is the ratio of the anelastic timescale
+to the viscoelastic Maxwell time of the mantle. Some uncertainty in this
+parameter's frequency-dependence does not influence our principal conclusions.",1105.3936v12
+2014-10-07,The Effect of Nonlinear Landau Damping on Ultrarelativistic Beam Plasma Instabilities,"Very-high energy gamma-rays from extragalactic sources pair-produce off of
+the extragalactic background light, yielding an electron-positron pair beam.
+This pair beam is unstable to various plasma instabilities, especially the
+""oblique"" instability, which can be the dominant cooling mechanism for the
+beam. However, recently, it has been claimed that nonlinear Landau damping
+renders it physically irrelevant by reducing the effective damping rate to a
+low level. Here, we show with numerical calculations that the effective damping
+rate is $8\times 10^{-4}$ of the growth rate of the linear instability, which
+is sufficient for the ""oblique"" instability to be the dominant cooling
+mechanism of these pair beams. In particular, we show that previous estimates
+of this rate ignored the exponential cutoff in the scattering amplitude at
+large wavenumber and assumed that the damping of scattered waves entirely
+depends on collisions, ignoring collisionless processes. We find that the total
+wave energy eventually grows to approximate equipartition with the beam by
+increasingly depositing energy into long wavelength modes. As we have not
+included the effect of nonlinear wave-wave interactions on these long
+wavelength modes, this scenario represents the ""worst-case"" scenario for the
+oblique instability. As it continues to drain energy from the beam at a faster
+rate than other processes, we conclude that the ""oblique"" instability is
+sufficiently strong to make it the physically dominant cooling mechanism for
+high-energy pair beams in the intergalactic medium.",1410.3797v2
+2014-10-17,Hunting down systematics in baryon acoustic oscillations after cosmic high noon,"Future dark energy experiments will require better and more accurate
+theoretical predictions for the baryonic acoustic oscillations (BAO) signature
+in the spectrum of cosmological perturbations. Here, we use large N-body
+simulations of the \LambdaCDM Planck cosmology to study any possible systematic
+shifts and damping in BAO due to the impact of nonlinear gravitational growth
+of structure, scale dependent and non-local bias, and redshift-space
+distortions. The effect of cosmic variance is largely reduced by dividing the
+tracer power spectrum by that from a BAO-free simulation starting with the same
+phases. This permits us to study with unprecedented accuracy (better than 0.02%
+for dark matter and 0.07% for low-bias halos) small shifts of the pristine BAO
+wavenumbers towards larger k, and non-linear damping of BAO wiggles in the
+power spectrum of dark matter and halo populations in the redshift range z=0-1.
+For dark matter, we provide an accurate parametrization of the evolution of
+\alpha as a function of the linear growth factor D(z). For halo samples, with
+bias ranging from 1.2 to 2.8, we measure a typical BAO shift of ~0.25%,
+observed in real-space, which does not show an appreciable evolution with
+redshift within the uncertainties. Moreover, we report a constant shift as a
+function of halo bias. We find a different evolution of the damping of the
+acoustic feature in all halo samples as compared to dark matter with haloes
+suffering less damping, and also find some weak dependence on bias. A larger
+BAO shift and damping is measured in redshift-space which can be well explained
+by linear theory due to redshift-space distortions. A clear modulation in phase
+with the acoustic scale is observed in the scale-dependent halo bias due to the
+presence of the baryonic acoustic oscillations.",1410.4684v2
+2017-01-24,Influence of interlayer coupling on the spin torque driven excitations in a spin torque oscillator,"The influence of dynamic interlayer interactions on the spin torque driven
+and damped excitations are illustrated for a three layer macrospin model system
+that corresponds to a standard spin-torque oscillator. The free layer and a
+synthetic antiferromagnetic (SyF) pinned layer of the spin-torque oscillator
+are in-plane magnetized. In order to understand experimental results, numerical
+simulations have been performed considering three types of interlayer
+interactions: exchange interaction between the two magnetic layers of the SyF,
+mutual spin torque between the top layer of the SyF and the free layer and
+dipolar interaction between all three magnetic layers. It will be shown that
+the dynamic dipolar coupling plays a predominant role. First, it leads to a
+hybridization of the free layer and the SyF linear modes and through this gives
+rise to a strong field dependence of the critical current. In particular, there
+is a field range of enhanced damping in which much higher current is required
+to drive the modes into steady state. This results in a gap in the excitation
+spectrum. Second, the dynamic dipolar interaction is also responsible for the
+non-linear interaction between the current driven steady state mode and the
+damped modes of the system. Here one can distinguish: (i) a resonant
+interaction that leads to a kink in the frequency-field and frequency-current
+dispersions accompanied by a small hysteresis and a reduction of the linewidth
+of the steady state mode and (ii) a non-resonant interaction that leads to a
+strong frequency redshift of the damped mode. The results underline the strong
+impact of interlayer coupling on the excitation spectra of spin-torque
+oscillators and illustrate in a simple three mode model system how in the
+non-linear regime the steady state and damped modes influence each other.",1701.06787v1
+2017-04-07,Global Alfven Eigenmodes in the H-1 heliac,"Recent upgrades in H-1 power supplies have enabled the operation of the H-1
+experiment at higher heating powers than previously attainable. A heating power
+scan in mixed hydrogen/helium plasmas reveals a change in mode activity with
+increasing heating power. At low power (<50 kW) modes with beta-induced Alfven
+eigenmode (BAE) frequency scaling are observed. At higher power modes
+consistent with an analysis of nonconventional Global Alfven Eigenmodes (GAEs)
+are observed, the subject of this work. We have computed the mode continuum,
+and identified GAE structures using the ideal MHD solver CKA and the
+gyrokinetic code EUTERPE. An analytic model for ICRH-heated minority ions is
+used to estimate the fast ion temperature from the hydrogen species. Linear
+growth rate scans using a local flux surface stability calculation, LGRO, are
+performed. These studies demonstrate growth from circulating particles whose
+speed is significantly less than the Alfven speed, and are resonant with the
+mode through harmonics of the Fourier decomposition of the strongly-shaped
+heliac magnetic field. They reveal drive is possible with a small, hot
+energetic tail of the hydrogen species. Local linear growth rate scans are also
+complemented with global calculations from CKA and EUTERPE. These qualitatively
+confirm the findings from the LGRO study, and show that the inclusion of finite
+Larmor radius effects can reduce the growth rate by a factor of three, but do
+not affect marginal stability. Finally, a study of damping of the global mode
+with the thermal plasma is conducted, computing continuum, and the damping
+arising from parallel electric fields. We find that continuum damping is of
+order 0.1% for the configuration studied. The inclusion of resistivity lifts
+the damping to 19%. Such large damping is consistent with experimental
+observations that in absence of drive the mode decays rapidly (~0.1 ms).",1704.02089v1
+2017-11-30,Scalar dark matter interpretation of the DAMPE data with U(1) gauge interactions,"Recently, DAMPE experiment released the new measurement of the total cosmic
+$e^+e^-$ flux between 25 GeV and 4.6 TeV which indicates a spectral softening
+at around 0.9 TeV and a tentative peak at around 1.4 TeV. We utilize the scalar
+dark matter (DM) annihilation scenario to explain the DAMPE peak by extending
+$G_{SM}\equiv SU(3)_C \times SU(2)_L \times U(1)_Y$ with additional $U(1)$
+gauge symmetries while keeping anomaly free to generate $\chi \chi \to Z^\prime
+Z^\prime \to \ell\bar{\ell}\ell^\prime\overline{\ell^\prime}$, where $\chi,
+Z^\prime, \ell^{(^\prime)}$ denote the scalar DM, the new gauge boson and
+$\ell^{(^\prime)}=e,\mu,\tau$, respectively, with $m_\chi \sim m_{Z^\prime}
+\sim 2 \times 1.5$ (TeV). We first illustrate that the minimal framework
+$G_{SM} \times U(1)_{Y^\prime}$ with the above mass choices can explain the
+DAMPE excess but has been excluded by LHC constraints from the $Z^\prime$
+searches. Then we study a non-minimal framework $G_{SM} \times U(1)_{Y^\prime}
+\times U(1)_{Y^{\prime \prime}}$ in which $U(1)_{Y^{\prime \prime}}$ mixes with
+$U(1)_{Y^\prime}$. We show that such a framework can interpret the DAMPE data
+while passing other constraints including the DM relic abundance, DM direct
+detection and collider bounds. We also investigate the predicted $e^+e^-$
+spectrum in this framework and find that the mass splitting $\Delta m = m_\chi
+- m_{Z'}$ should be less than about 17 GeV to produce the peak-like structure.",1711.11452v2
+2017-12-14,Scalar dark matter explanation of the DAMPE data in the minimal Left-Right symmetric model,"Left-Right symmetric model (LRSM) has been an attractive extension of the
+Standard Model (SM) which can address the origin of parity violation in the SM
+electroweak (EW) interactions, generate tiny neutrino masses, accommodate dark
+matter (DM) candidates and provide a natural framework for baryogenesis through
+leptogenesis. In this work we utilize the minimal LRSM to study the recently
+reported DAMPE results of cosmic $e^+e^-$ spectrum which exhibits a tentative
+peak around 1.4 TeV, while satisfying the current neutrino data. We propose to
+explain the DAMPE peak with a complex scalar DM $\chi$ in two scenarios: 1)
+$\chi\chi^* \to H_1^{++}H_1^{--} \to \ell_i^+\ell_i^+\ell_j^-\ell_j^-$; 2)
+$\chi\chi^* \to H_{k}^{++}H_{k}^{--} \to \ell_i^+\ell_i^+\ell_j^-\ell_j^-$
+accompanied by $\chi\chi^* \to H_1^+ H_1^- \to \ell_i^+ \nu_{\ell_i} \ell_j^-
+\nu_{\ell_j}$ with $\ell_{i,j}=e,\mu,\tau$ and $k=1,2$. We fit the theoretical
+prediction on $e^+e^-$ spectrum to relevant experimental data to determine the
+scalar mass spectrum favored by the DAMPE excess. We also consider various
+constraints from theoretical principles, collider experiments as well as DM
+relic density and direct search experiments. We find that there are ample
+parameter space which can interpret the DAMPE data while passing the
+constraints. Our explanations, on the other hand, usually imply the existence
+of other new physics at the energy scale ranging from $10^7 {\rm GeV}$ to
+$10^{11} {\rm GeV}$. Collider tests of our explanations are also discussed.",1712.05351v3
+2018-02-20,The chemical connection between damped Lyman-α systems and Local Group dwarf galaxies,"Abundances of the volatile elements S and Zn have now been measured in around
+80 individual stars in the Sculptor dwarf spheroidal galaxy, covering the
+metallicity range $-2.4\leq\text{[Fe/H]}\leq-0.9$. These two elements are of
+particular interest as they are not depleted onto dust in gas, and their ratio,
+[S/Zn], has thus commonly been used as a proxy for [$\alpha$/Fe] in Damped
+Lyman-$\alpha$ systems. The S abundances in Sculptor are similar to other
+$\alpha$-elements in this galaxy, consistent with S being mainly created in
+core-collapse supernovae, but also having some contribution from supernovae
+Type Ia. However, our results show that Zn and Fe do not trace all the same
+nucleosynthetic production channels. In particular, (contrary to Fe) Zn is not
+significantly produced by supernovae Type Ia. Thus, [S/Zn] cannot be reliably
+used as a proxy for [$\alpha$/Fe]. We propose [O/S] as a function of [S/H] as a
+possible alternative. At higher metallicities, the values of [S/Zn] measured in
+Damped Lyman-$\alpha$ systems are inconsistent with those in local dwarf
+galaxies, and are more compatible with the Milky Way disk. Low-metallicity
+Damped Lyman-$\alpha$ systems are, however, consistent with the most metal-poor
+stars in Local Group dwarf spheroidal galaxies. Assuming that the dust
+depletions of S and Zn are negligible, our comparison indicates that the star
+formation histories of Damped Lyman-$\alpha$ systems are on average different
+from both the Milky Way and the Sculptor dwarf spheroidal galaxy.",1802.07325v5
+2019-01-12,GW170817 implications on the frequency and damping time of f-mode oscillations of neutron stars,"Within a minimum model for neutron stars consisting of nucleons, electrons
+and muons at $\beta$-equilibrium using about a dozen Equation of States (EOSs)
+from microscopic nuclear many-body theories and 40,000 EOSs randomly generated
+using an explicitly isospin-dependent parametric EOS model for high-density
+neutron-rich nucleonic matter within its currently known uncertainty range, we
+study correlations among the f-mode frequency, its damping time and the tidal
+deformability as well as the compactness of neutron stars. Except for quark
+stars, both the f-mode frequency and damping time of canonical neutron stars
+are found to scale with the tidal deformability independent of the EOSs used.
+Applying the constraint on the tidal deformability of canonical neutron stars
+$\Lambda_{1.4}=190^{+390}_{-120}$ extracted by the LIGO+VIRGO Collaborations
+from their improved analyses of the GW170817 event, the f-mode frequency and
+its damping time of canonical neutron stars are limited to 1.67 kHz - 2.18 kHz
+and 0.155 s - 0.255 s, respectively, providing a useful guidance for the
+ongoing search for gravitational waves from the f-mode oscillations of isolated
+neutron stars. Moreover, assuming either or both the f-mode frequency and its
+damping time will be measured precisely in future observations with advanced
+gravitational wave detectors, we discuss how information about the mass and/or
+radius as well as the still rather elusive nuclear symmetry energies at
+supra-saturation densities may be extracted.",1901.03779v2
+2019-01-27,"An introductory guide to fluid models with anisotropic temperatures Part 2 -- Kinetic theory, Padé approximants and Landau fluid closures","In Part 2 of our guide to collisionless fluid models, we concentrate on
+Landau fluid closures. These closures were pioneered by Hammett and Perkins and
+allow for the rigorous incorporation of collisionless Landau damping into a
+fluid framework. It is Landau damping that sharply separates traditional fluid
+models and collisionless kinetic theory, and is the main reason why the usual
+fluid models do not converge to the kinetic description, even in the
+long-wavelength low-frequency limit. We start with a brief introduction to
+kinetic theory, where we discuss in detail the plasma dispersion function
+$Z(\zeta)$, and the associated plasma response function $R(\zeta)=1+\zeta
+Z(\zeta)=-Z'(\zeta)/2$. We then consider a 1D (electrostatic) geometry and make
+a significant effort to map all possible Landau fluid closures that can be
+constructed at the 4th-order moment level. These closures for parallel moments
+have general validity from the largest astrophysical scales down to the Debye
+length, and we verify their validity by considering examples of the (proton and
+electron) Landau damping of the ion-acoustic mode, and the electron Landau
+damping of the Langmuir mode. We proceed by considering 1D closures at
+higher-order moments than the 4th-order, and as was concluded in Part 1, this
+is not possible without Landau fluid closures. We show that it is possible to
+reproduce linear Landau damping in the fluid framework to any desired
+precision, thus showing the convergence of the fluid and collisionless kinetic
+descriptions. We then consider a 3D (electromagnetic) geometry in the
+gyrotropic (long-wavelength low-frequency) limit and map all closures that are
+available at the 4th-order moment level. In the Appendix A, we provide
+comprehensive tables with Pad\'e approximants of $R(\zeta)$ up to the 8th-pole
+order, with many given in an analytic form.",1901.09360v2
+2019-01-28,Revisit of non-linear Landau damping for electrostatic instability driven by blazar-induced pair beams,"We revisit the effect of non-linear Landau (NL) damping on the electrostatic
+instability of blazar-induced pair beams, using a realistic pair-beam
+distribution. We employ a simplified 2D model in ${\bf k}$-space to study the
+evolution of the electric-field spectrum and to calculate the relaxation time
+of the beam. We demonstrate that the 2D model is an adequate representation of
+the 3D physics. We find that non-linear Landau damping, once it operates
+efficiently, transports essentially the entire wave energy to small wavenumbers
+where wave driving is weak or absent. The relaxation time also strongly depends
+on the IGM temperature, $T_\mathrm{IGM}$, and for $T_\mathrm{IGM}\ll10$ eV, and
+in the absence of any other damping mechanism, the relaxation time of the pair
+beam is longer than the inverse Compton (IC) scattering time. The weak
+late-time beam energy losses arise from the accumulation of wave energy at
+small $k$, that non-linearly drains the wave energy at the resonant
+$\mathbf{k}$ of the pair-beam instability. Any other dissipation process
+operating at small $k$ would reduce that wave-energy drain and hence lead to
+stronger pair-beam energy losses. As an example, collisions reduce the
+relaxation time by an order of magnitude, although their rate is very small.
+Other non-linear processes, such as the modulation instability, could provide
+additional damping of the non-resonant waves and dramatically reduce the
+relaxation time of the pair beam. An accurate description of the spectral
+evolution of the electrostatic waves is crucial for calculating the relaxation
+time of the pair beam.",1901.09640v3
+2019-11-22,"Role of Element-Specific Damping on the Ultrafast, Helicity-Independent All-Optical Switching Dynamics in Amorphous (Gd,Tb)Co Thin Films","Ultrafast control of the magnetization in ps timescales by fs laser pulses
+offers an attractive avenue for applications such as fast magnetic devices for
+logic and memory. However, ultrafast helicity-independent all-optical switching
+(HI-AOS) of the magnetization has thus far only been observed in Gd-based,
+ferrimagnetic amorphous (\textit{a}-) rare earth-transition metal
+(\textit{a}-RE-TM) systems, and a comprehensive understanding of the reversal
+mechanism remains elusive. Here, we report HI-AOS in ferrimagnetic
+\textit{a}-Gd$_{22-x}$Tb$_x$Co$_{78}$ thin films, from x = 0 to x = 18, and
+elucidate the role of Gd in HI-AOS in \textit{a}-RE-TM alloys and multilayers.
+Increasing Tb content results in increasing perpendicular magnetic anisotropy
+and coercivity, without modifying magnetization density, and slower
+remagnetization rates and higher critical fluences for switching but still
+shows picosecond HI-AOS. Simulations of the atomistic spin dynamics based on
+the two-temperature model reproduce these results qualitatively and predict
+that the lower damping on the RE sublattice arising from the small spin-orbit
+coupling of Gd (with $L = 0$) is instrumental for the faster dynamics and lower
+critical fluences of the Gd-rich alloys. Annealing
+\textit{a}-Gd$_{10}$Tb$_{12}$Co$_{78}$ leads to slower dynamics which we argue
+is due to an increase in damping. These simulations strongly indicate that
+acounting for element-specific damping is crucial in understanding HI-AOS
+phenomena. The results suggest that engineering the element specific damping of
+materials can open up new classes of materials that exhibit low-energy,
+ultrafast HI-AOS.",1911.09803v3
+2020-06-08,Hysteretic depinning of a particle in a periodic potential: Phase diagram and criticality,"We consider a massive particle driven with a constant force in a periodic
+potential and subjected to a dissipative friction. As a function of the drive
+and damping, the phase diagram of this paradigmatic model is well known to
+present a pinned, a sliding, and a bistable regime separated by three distinct
+bifurcation lines. In physical terms, the average velocity $v$ of the particle
+is nonzero only if either (i) the driving force is large enough to remove any
+stable point, forcing the particle to slide, or (ii) there are local minima but
+the damping is small enough, below a critical damping, for the inertia to allow
+the particle to cross barriers and follow a limit cycle; this regime is
+bistable and whether $v > 0$ or $v = 0$ depends on the initial state. In this
+paper, we focus on the asymptotes of the critical line separating the bistable
+and the pinned regimes. First, we study its behavior near the ""triple point""
+where the pinned, the bistable, and the sliding dynamical regimes meet. Just
+below the critical damping we uncover a critical regime, where the line
+approaches the triple point following a power-law behavior. We show that its
+exponent is controlled by the normal form of the tilted potential close to its
+critical force. Second, in the opposite regime of very low damping, we revisit
+existing results by providing a simple method to determine analytically the
+exact behavior of the line in the case of a generic potential. The analytical
+estimates, accurately confirmed numerically, are obtained by exploiting exact
+soliton solutions describing the orbit in a modified tilted potential which can
+be mapped to the original tilted washboard potential. Our methods and results
+are particularly useful for an accurate description of underdamped nonuniform
+oscillators driven near their triple point.",2006.04912v2
+2020-09-14,Large field-like torque in amorphous Ru2Sn3 originated from the intrinsic spin Hall effect,"We investigated temperature dependent current driven spin-orbit torques in
+magnetron sputtered Ru2Sn3 (4 and 10 nm) /Co20Fe60B20 (5 nm) layered structures
+with in-plane magnetic anisotropy. The room temperature damping-like and
+field-like spin torque efficiencies of the amorphous Ru2Sn3 films were measured
+to be 0.14 +- 0.008 (0.07 +- 0.012) and -0.03 +- 0.006 (-0.20 +- 0.009), for
+the 4 (10 nm) films respectively, by utilizing the second harmonic Hall
+technique. The large field-like torque in the relatively thicker Ru2Sn3 (10 nm)
+thin film is unique compared to the traditional spin Hall materials interfaced
+with thick magnetic layers with in-plane magnetic anisotropy which typically
+have dominant damping-like and negligible field-like torques. Additionally, the
+observed room temperature field-like torque efficiency in Ru2Sn3 (10 nm)/CoFeB
+(5 nm) is up to three times larger than the damping-like torque (-0.20 +- 0.009
+and 0.07 +- 0.012, respectively) and thirty times larger at 50 K (-0.29 +-
+0.014 and 0.009 +- 0.017, respectively). The temperature dependence of the
+field-like torques show dominant contributions from the intrinsic spin Hall
+effect while the damping-like torques show dominate contributions from the
+extrinsic spin Hall effects, skew scattering and side jump. Through macro-spin
+calculations, we found that including field-like torques on the order or larger
+than the damping-like torque can reduce the switching critical current and
+decrease magnetization procession for a perpendicular ferromagnetic layer.",2009.06711v2
+2021-01-12,Phase Retrieval using Expectation Consistent Signal Recovery Algorithm based on Hypernetwork,"Phase retrieval (PR) is an important component in modern computational
+imaging systems. Many algorithms have been developed over the past
+half-century. Recent advances in deep learning have introduced new
+possibilities for a robust and fast PR. An emerging technique called deep
+unfolding provides a systematic connection between conventional model-based
+iterative algorithms and modern data-based deep learning. Unfolded algorithms,
+which are powered by data learning, have shown remarkable performance and
+convergence speed improvement over original algorithms. Despite their
+potential, most existing unfolded algorithms are strictly confined to a fixed
+number of iterations when layer-dependent parameters are used. In this study,
+we develop a novel framework for deep unfolding to overcome existing
+limitations. Our development is based on an unfolded generalized expectation
+consistent signal recovery (GEC-SR) algorithm, wherein damping factors are left
+for data-driven learning. In particular, we introduce a hypernetwork to
+generate the damping factors for GEC-SR. Instead of learning a set of optimal
+damping factors directly, the hypernetwork learns how to generate the optimal
+damping factors according to the clinical settings, thereby ensuring its
+adaptivity to different scenarios. To enable the hypernetwork to adapt to
+varying layer numbers, we use a recurrent architecture to develop a dynamic
+hypernetwork that generates a damping factor that can vary online across
+layers. We also exploit a self-attention mechanism to enhance the robustness of
+the hypernetwork. Extensive experiments show that the proposed algorithm
+outperforms existing ones in terms of convergence speed and accuracy and still
+works well under very harsh settings, even under which many classical PR
+algorithms are unstable.",2101.04348v2
+2021-06-18,Sloshing dynamics of liquid tank with built-in buoys for wave energy harvesting,"This paper proposes a novel design of liquid tank with built-in buoys for
+wave energy harvesting, named the 'sloshing wave energy converter (S-WEC)'.
+When the tank is oscillated by external loads (such as ocean waves), internal
+liquid sloshing is activated, and the mechanical energy of sloshing waves can
+be absorbed by the power take-off (PTO) system attached to these buoys. A
+fully-nonlinear numerical model is established based on the boundary element
+method for a systematic investigation on dynamic properties of the proposed
+S-WEC. A motion decoupling algorithm based on auxiliary functions is developed
+to solve the nonlinear interaction of sloshing waves and floating buoys in the
+tank. An artificial damping model is introduced to reflect viscous effects of
+the sloshing liquid. Physical experiments are carried out on a scaled S-WEC
+model to validate the mathematical and numerical methodologies. Natural
+frequencies of the S-WEC system are first investigated through spectrum
+analyses on motion histories of the buoy and sloshing liquid. The viscous
+damping strength is identified through comparisons with experimental
+measurements. Effects of the PTO damping on power generation characteristics of
+S-WEC is further explored. An optimal PTO damping can be found for each
+excitation frequency, leading to the maximisation of both the power generation
+and conversion efficiency of the buoy. To determine a constant PTO damping for
+engineering design, a practical approach based on diagram analyses is proposed.
+Effects of the buoy's geometry on power generation characteristics of the S-WEC
+are also investigated. In engineering practice, the present design of S-WEC can
+be a promising technical solution of ocean wave energy harvesting, based on its
+comprehensive advantages on survivability enhancement, metal corrosion or
+fouling organism inhibition, power generation stability and efficiency, and so
+on.",2106.10005v1
+2005-03-31,Study of the angular coefficients and corresponding helicity cross sections of the W boson in hadron collisions,"We present the Standard Model prediction for the eight angular coefficients
+of the W boson, which completely describe its differential cross section in
+hadron collisions. These coefficients are ratios of the W helicity cross
+sections and the total unpolarized cross section. We also suggest a technique
+to experimentally extract the coefficients.",0503291v1
+1992-06-08,su(3)k fusion coefficients,"A closed and explicit formula for all $\su{(3)}_k$ fusion coefficients is
+presented which, in the limit $k \rightarrow \infty$, turns into a simple and
+compact expression for the $su(3)$ tensor product coefficients. The derivation
+is based on a new diagrammatic method which gives directly both tensor product
+and fusion coefficients.",9206032v1
+2005-11-15,Power series coefficients for probabilities in finite classical groups,"It is shown that a wide range of probabilities and limiting probabilities in
+finite classical groups have integral coefficients when expanded as a power
+series in 1/q. Moreover it is proved that the coefficients of the limiting
+probabilities in the general linear and unitary cases are equal modulo 2. The
+rate of stabilization of the finite dimensional coefficients as the dimension
+increases is discussed.",0511390v1
+2007-09-20,Uniform Convergence of the Spectral Expansion for a Differential Operator with Periodic Matrix Coefficients,"In this paper, we obtain asymptotic formulas for eigenvalues and
+eigenfunctions of the operator generated by a system of ordinary differential
+equations with summable coefficients and the quasiperiodic boundary conditions.
+Using these asymptotic formulas, we find conditions on the coefficients for
+which the root functions of this operator form a Riesz basis. Then we obtain
+the uniformly convergent spectral expansion of the differential operators with
+the periodic matrix coefficients",0709.3190v1
+2007-11-07,A Diagrammatic Approach for the Coefficients of the Characteristic Polynomial,"In this work we provide a novel approach for computing the coefficients of
+the characteristic polynomial of a square matrix. We demonstrate that each
+coefficient can be efficiently represented by a set of circle graphs. Thus, one
+can employ a diagrammatic approach to determine the coefficients of the
+characteristic polynomial.",0711.1032v1
+2008-11-12,Some Probabilistic and Statistical Properties of a Random Coefficient Autoregressive Model,"A statistical inference for random coefficient first-order autoregressive
+model $[RCAR(1)]$ was investigated by P.M. ROBINSON (1978) in which the
+coefficients varying over individuals. In this paper we attempt to generalize
+this result to random coefficient autoregressive model of order $p$
+$[RCAR(p)]$. The stationarity condition will derived for this model.",0811.1846v1
+2009-03-04,On the Differential Operators with Periodic Matrix Coefficients,"In this article we obtain asymptotic formulas for eigenvalues and
+eigenfunctions of the operator generated by a system of ordinary differential
+equations with summable coefficients and quasiperiodic boundary conditions.
+Then using these asymptotic formulas, we find conditions on the coefficients
+for which the number of gaps in the spectrum of the self-adjoint differential
+operator with the periodic matrix coefficients is finite.",0903.0776v1
+2009-04-27,SO(5) Clebsch-Gordan coefficients involving the 14-dimensional representation,"Analytic expressions for the Clebsch-Gordan (CG) coefficients of the SO(5)
+group that involve the 14-dimensional representation can be found in an old
+paper of M. K. F. Wong. A careful analysis yields that roughly 30% of the
+coefficients given in that paper are wrong. The correct analytic expressions
+for all SO(5) group CG coefficients containing the 14-dimensional
+representation are obtained.",0904.4200v1
+2010-01-18,Coefficients in powers of the log series,"We determine the p-exponent in many of the coefficients in the power series
+(log(1+x)/x)^t, where t is any integer. In our proof, we introduce a variant of
+multinomial coefficients. We also characterize the power series x/log(1+x) by
+certain zero coefficients in its powers.",1001.3068v1
+2011-04-05,Comparison of Weibull tail-coefficient estimators,"We address the problem of estimating the Weibull tail-coefficient which is
+the regular variation exponent of the inverse failure rate function. We propose
+a family of estimators of this coefficient and an associate extreme quantile
+estimator. Their asymptotic normality are established and their asymptotic
+mean-square errors are compared. The results are illustrated on some finite
+sample situations.",1104.0764v1
+2011-07-05,Solution of Fokker-Planck equation for a broad class of drift and diffusion coefficients,"We consider a Langevin equation with variable drift and diffusion
+coefficients separable in time and space and its corresponding Fokker-Planck
+equation in the Stratonovich approach. From this Fokker-Planck equation we
+obtain a class of exact solutions with the same spatial drift and diffusion
+coefficients. Furthermore, we analyze some details of this system by using the
+spatial diffusion coefficient $D(x)=\sqrt{D}|x| ^{-% \frac{\theta}{2}}$.",1107.0959v1
+2011-07-13,Identification of the coefficients in the linear Boltzmann equation by a finite number of boundary measurements,"In this paper we consider an inverse problem for the time dependent linear
+Boltzmann equation. It concerns the identification of the coefficients via a
+finite number of measurements on the boundary. We prove that the total
+extinction coefficient and the collision kernel can be uniquely determined by
+at most k measurements on the boundary, provided that these coefficients belong
+to a finite k-dimensional vector space.",1107.2682v1
+2012-02-01,A generalization of the Gaussian formula and a q-analog of Fleck's congruence,"The q-binomial coefficients are the polynomial cousins of the traditional
+binomial coefficients, and a number of identities for binomial coefficients can
+be translated into this polynomial setting. For instance, the familiar
+vanishing of the alternating sum across row n of Pascal's triangle is captured
+by the so-called Gaussian Formula. In this paper, we find a q-binomial
+congruence which synthesizes this result and Fleck's congruence for binomial
+coefficients.",1202.0199v1
+2012-05-03,On some binomial coefficients related to the evaluation of tan(nx),"The purpose of this paper is to study some binomial coefficients which are
+related to the evaluation of tan(nx). We present a connection between these
+binomial coefficients and the coefficients of a family of derivative
+polynomials for tangent and secant.",1205.0735v4
+2012-08-01,Applications of Theory of Differential Subordination for Functions with Fixed Initial Coefficient to Univalent Functions,"By using the theory of first-order differential subordination for functions
+with fixed initial coefficient, several well-known results for subclasses of
+univalent functions are improved by restricting the functions to have fixed
+second coefficient. The influence of the second coefficient of univalent
+functions is evident in the results obtained.",1208.0148v1
+2013-11-12,Strong Rate of Convergence for the Euler-Maruyama Approximation of Stochastic Differential Equations with Irregular Coefficients,"We consider the Euler-Maruyama approximation for multi-dimensional stochastic
+differential equations with irregular coefficients. We provide the rate of
+strong convergence where the possibly discontinuous drift coefficient satisfies
+a one-sided Lipschitz condition and the diffusion coefficient is H\""older
+continuous.",1311.2725v2
+2014-03-08,Functional equations for double series of Euler-Hurwitz-Barnes type with coefficients,"We first survey the known results on functional equations for the double
+zeta-function of Euler type and its various generalizations. Then we prove two
+new functional equations for double series of Euler-Hurwitz-Barnes type with
+complex coefficients. The first one is of general nature, while the second one
+is valid when the coefficients are Fourier coefficients of a cusp form.",1403.1940v1
+2014-04-09,$L^p(Ω)$-Difference of One-Dimensional Stochastic Differential Equations with Discontinuous Drift,"We consider a one-dimensional stochastic differential equations (SDE) with
+irregular coefficients. The purpose of this paper is to estimate the
+$L^p(\Omega)$-difference of SDEs using the norm of the difference of
+coefficients, where the discontinuous drift coefficient satisfies a one-sided
+Lipschitz condition and the diffusion coefficient is bounded, uniformly
+elliptic and H\""older continuous. As an application, we consider the stability
+problem.",1404.2358v1
+2014-05-20,Convergence of a Metropolized Integrator for Stochastic Differential Equations with Variable Diffusion Coefficient,"We present an explicit method for simulating stochastic differential
+equations (SDEs) that have variable diffusion coefficients and satisfy the
+detailed balance condition with respect to a known equilibrium density. In
+Tupper and Yang (2012), we proposed a framework for such systems in which,
+instead of a diffusion coefficient and a drift coefficient, a modeller
+specifies a diffusion coefficient and a equilibrium density, and then assumes
+detailed balance with respect to this equilibrium density. We proposed a
+numerical method for such systems that works directly with the diffusion
+coefficient and equilibrium density, rather than the drift coefficient, and
+uses a Metropolis-Hastings rejection process to preserve the equilibrium
+density exactly. Here we show that the method is weakly convergent with order
+1/2 for such systems with smooth coefficients. We perform numerical experiments
+demonstrating the convergence of the method for systems not covered by our
+theorem, including systems with discontinuous diffusion coefficients and
+equilibrium densities.",1405.5264v2
+2014-07-06,Deligne categories and reduced Kronecker coefficients,"The Kronecker coefficients are the structural constants for the tensor
+categories of representations of the symmetric groups; namely, given three
+partitions $\lambda, \mu, \tau$ of $n$, the multiplicity of $\lambda$ in $\mu
+\otimes \tau$ is called the Kronecker coefficient $g^{\lambda}_{\mu, \tau}$.
+  When the first part of each of the partitions is taken to be very large (the
+remaining parts being fixed), the values of the appropriate Kronecker
+coefficients stabilize; the stable value is called the reduced (or stable)
+Kronecker coefficient. These coefficients also generalize the
+Littlewood-Richardson coefficients, and have been studied quite extensively.
+  In this paper, we show that reduced Kronecker coefficients appear naturally
+as structure constants of the Deligne categories $\underline{Rep}(S_t)$. This
+allows us to interpret various properties of the reduced Kronecker coefficients
+as categorical properties of the categories $\underline{Rep}(S_t)$.",1407.1506v1
+2014-12-08,On the optimal estimates and comparison of Gegenbauer expansion coefficients,"In this paper, we study optimal estimates and comparison of the coefficients
+in the Gegenbauer series expansion. We propose an alternative derivation of the
+contour integral representation of the Gegenbauer expansion coefficients which
+was recently derived by Cantero and Iserles [SIAM J. Numer. Anal., 50 (2012),
+pp.307-327]. With this representation, we show that optimal estimates for the
+Gegenbauer expansion coefficients can be derived, which in particular includes
+Legendre coefficients as a special case. Further, we apply these estimates to
+establish some rigorous and computable bounds for the truncated Gegenbauer
+series. In addition, we compare the decay rates of the Chebyshev and Legendre
+coefficients. For functions whose singularity is outside or at the endpoints of
+the expansion interval, asymptotic behaviour of the ratio of the nth Legendre
+coefficient to the nth Chebyshev coefficient is given, which provides us an
+illuminating insight for the comparison of the spectral methods based on
+Legendre and Chebyshev expansions.",1412.2525v3
+2015-04-25,"Improved Vietoris Sine Inequalities for Non-Monotone, Non-Decaying Coefficients","Recently the author established an improvement of the classical Vietoris sine
+inequality to include sine polynomials with non-monotone coefficients.
+  In this paper two further improvements are presented admitting sine
+polynomials with non-monotone and non-decaying coefficients.
+  The extremal sums of the two results have the coefficient sequences {2a, a,
+4/3, 1, 6/5, 1, 8/7, 1, ...}, where a = 0.78265..., and {3, 3/2, 7/3, 7/4,
+11/5, 11/6, ...}.",1504.06705v1
+2015-05-16,Relation Functions Evaluated from Unique Coefficient Patterns,"In this paper, we study polynomials of the form $f(x)=(x^n+x^{n-1}+...+1)^l$
+for $l=1,2,3,4$ to generate a pattern titled ""unique coefficient pattern"".
+Namely, we analyze each unique coefficient patterns of $f(x)$ and generate
+functions titled ""relation functions"". The approach that we follow will allow
+us to evaluate desired coefficients for such polynomial expansions by simply
+using these relation functions.",1505.04325v1
+2015-06-05,Cluster automorphism groups of cluster algebras with coefficients,"We study the cluster automorphism group of a skew-symmetric cluster algebra
+with geometric coefficients. For this, we introduce the notion of gluing free
+cluster algebra, and show that under a weak condition the cluster automorphism
+group of a gluing free cluster algebra is a subgroup of the cluster
+automorphism group of its principal part cluster algebra (i.e. the
+corresponding cluster algebra without coefficients). We show that several
+classes of cluster algebras with coefficients are gluing free, for example,
+cluster algebras with principal coefficients, cluster algebras with universal
+geometric coefficients, and cluster algebras from surfaces (except a 4-gon)
+with coefficients from boundaries. Moreover, except four kinds of surfaces, the
+cluster automorphism group of a cluster algebra from a surface with
+coefficients from boundaries is isomorphic to the cluster automorphism group of
+its principal part cluster algebra; for a cluster algebra with principal
+coefficients, its cluster automorphism group is isomorphic to the automorphism
+group of its initial quiver.",1506.01942v1
+2015-07-28,Some identities involving polynomial coefficients,"By polynomial (or extended binomial) coefficients, we mean the coefficients
+in the expansion of integral powers, positive and negative, of the polynomial
+$1+t +\cdots +t^{m}$; $m\geq 1$ being a fixed integer. We will establish
+several identities and summation formul\ae\ parallel to those of the usual
+binomial coefficients.",1507.07968v2
+2016-03-12,On alternating sums of binomial coefficients and $q$-binomial coefficients,"In this paper we shall evaluate two alternating sums of binomial coefficients
+by a combinatorial argument. Moreover, by combining the same combinatorial idea
+with partition theoretic techniques, we provide $q$-analogues involving the
+$q$-binomial coefficients.",1603.03881v2
+2016-04-27,Series extension: Predicting approximate series coefficients from a finite number of exact coefficients,"Given the first 20-100 coefficients of a typical generating function of the
+type that arises in many problems of statistical mechanics or enumerative
+combinatorics, we show that the method of differential approximants performs
+surprisingly well in predicting (approximately) subsequent coefficients. These
+can then be used by the ratio method to obtain improved estimates of critical
+parameters. In favourable cases, given only the first 20 coefficients, the next
+100 coefficients are predicted with useful accuracy. More surprisingly, this is
+also the case when the method of differential approximants does not do a useful
+job in estimating the critical parameters, such as those cases in which one has
+stretched exponential asymptotic behaviour. Nevertheless, the coefficients are
+predicted with surprising accuracy. As one consequence, significant computer
+time can be saved in enumeration problems where several runs would normally be
+made, modulo different primes, and the coefficients constructed from their
+values modulo different primes. Another is in the checking of newly calculated
+coefficients. We believe that this concept of approximate series extension
+opens up a whole new chapter in the method of series analysis.",1604.08254v1
+2016-09-26,A Note On Signs Of Fourier Coefficients Of Two Cusp Forms,"Kohnen and Sengupta proved that two cusp forms of different integral weights
+with real algebraic Fourier coefficients have infinitely many Fourier
+coefficients of the same as well as of opposite sign, up to the action of a
+Galois automorphism. Recently Gun, Kohnen and Rath strengthen their result by
+comparing the simultaneous sign changes of Fourier coefficients of two cusp
+forms with arbitrary real Fourier coefficients. The simultaneous sign changes
+of Fourier coefficients of two same integral weight cusp forms follow from an
+earlier work of Ram Murty. In this note we compare the signs of the Fourier
+coefficients of two cusp forms simultaneously for the congruence subgroup
+$\Gamma_0(\mathit{N})$ where the coefficients lie in an arithmetic progression.
+Next we consider an analogous question for the particular sparse sequences of
+Fourier coefficients of normalized Hecke eigen cusp forms for the full modular
+group.",1609.07938v2
+2016-11-29,Stapledon Decompositions and Inequalities for Coefficients of Chromatic Polynomials,"We use a polynomial decomposition result by Stapledon to show that the
+numerator polynomial of the Ehrhart series of an open polytope is the
+difference of two symmetric polynomials with nonnegative integer coefficients.
+We obtain a related decomposition for order polytopes and for the numerator
+polynomial of the corresponding series for chromatic polynomials. The
+nonnegativity of the coefficients in such decompositions provide inequalities
+satisfied by the coefficients of chromatic polynomials for any simple graph.",1611.09728v1
+2017-09-12,Langevin Diffusion Coefficients Ratio in STU Model with Higher Derivative Corrections,"In this letter, we study Langevin diffusion coefficients for the five
+dimensional $\mathcal{N}=2$ STU model in presence of higher derivative
+corrections. We obtained effect of black hole charge, corresponding to the
+chemical potential, on the Langevin diffusion coefficients ratio. We confirm
+universal behavior of transverse to longitudinal ratio of coefficients.",1709.06846v1
+2017-09-29,Equivalence of sparse and Carleson coefficients for general sets,"We remark that sparse and Carleson coefficients are equivalent for every
+countable collection of Borel sets and hence, in particular, for dyadic
+rectangles, the case relevant to the theory of bi-parameter singular integrals.
+  The key observation is that a dual refomulation by I. E. Verbitsky for
+Carleson coefficients over dyadic cubes holds also for Carleson coefficients
+over general sets. We give a simple proof for this reformulation.",1709.10457v1
+2018-09-21,The partition algebra and the plethysm coefficients I: stability and Foulkes' conjecture,"We propose a new approach to study plethysm coefficients by using the
+Schur-Weyl duality between the symmetric group and the partition algebra. This
+allows us to explain the stability properties of plethysm and Kronecker
+coefficients in a simple and uniform fashion for the first time. We prove the
+strengthened Foulkes' conjecture for stable plethysm coefficients in an
+elementary fashion.",1809.08128v2
+2018-10-09,A class of univalent functions with real coefficients,"In this paper we study class $\mathcal{S}^+$ of univalent functions $f$ such
+that $\frac{z}{f(z)}$ has real and positive coefficients. For such functions we
+give estimates of the Fekete-Szeg\H{o} functional and sharp estimates of their
+initial coefficients and logarithmic coefficients. Also, we present necessary
+and sufficient conditions for $f\in \mathcal{S}^+$ to be starlike of order
+$1/2$.",1810.03839v2
+2019-07-12,Tamagawa number formula with coefficients over varieties in positive characteristic,"We express the order of the pole and the leading coefficient of the
+L-function of a (large class of) -adic coefficients (any prime) over a
+quasi-projective variety over a finite field of characteristic p. This is a
+generalization of the result of Milne-Ramachandran with coefficients. The new
+key ingredient is the use of F-gauges and their equivalence in the derived
+category with Raynaud modules proved by Ekedahl.",1907.05838v1
+2019-10-21,Super-congruences involving trininomial coefficients,"The aim of this work is to establish congruences $\left(
+\operatorname{mod}p^{2}\right) $ involving the trinomial coefficients
+$\binom{np-1}{p-1}_{2}$ and $\binom{np-1}{\left( p-1\right)/2}_{2}$ arising
+from the expansion of the powers of the polynomial $1+x+x^{2}.$ In main results
+we extend some known congruences involving the binomial coefficients
+$\binom{np-1}{p-1}$ and $\binom{np-1}{\left( p-1\right) /2}$ and establish
+congruences link binomial coefficients and harmonic numbers.",1910.09262v1
+2020-01-06,On resolvent approximations of elliptic differential operators with periodic coefficients,"We study resolvent approximations for elliptic differential nonselfadjoint
+operators with periodic coefficients in the limit of the small period. The
+class of operators covered by our analysis includes uniformly elliptic families
+with bounded coefficients and also with unbounded coefficients from the
+John-Nirenberg space $BMO$ (bounded mean oscillation). We apply the modified
+method of the first approximation with the usage of Steklov's smoothing.",2001.01701v1
+2020-02-25,Upper bounds on Kronecker coefficients with few rows,"We present three different upper bounds for Kronecker coefficients
+$g(\lambda,\mu,\nu)$ in terms of Kostka numbers, contingency tables and
+Littlewood--Richardson coefficients. We then give various examples, asymptotic
+applications, and compare them with existing lower bounds.",2002.10956v2
+2020-03-13,Transforming ODEs and PDEs with radical coefficients into rational coefficients,"We present an algorithm that transforms, if possible, a given ODE or PDE with
+radical function coefficients into one with rational coefficients by means of a
+rational change of variables. It also applies to systems of linear ODEs. It is
+based on previous work on reparametrization of radical algebraic varieties.",2003.06301v1
+2020-04-09,Magneto-Seebeck coefficient and Nernst coefficient of hot and dense hadron gas,"We discuss the thermoelectric effect of hot and dense hadron gas within the
+framework of the hadron resonance gas model. Using the relativistic Boltzmann
+equation within the relaxation time approximation we estimate the Seebeck
+coefficient of the hot and dense hadronic medium with a gradient in temperature
+and baryon chemical potential. The hadronic medium in this calculation is
+modeled by the hadron resonance gas (HRG) model with hadrons and their
+resonances up to a mass cutoff $\Lambda\sim 2.6$ GeV. We also extend the
+formalism of the thermoelectric effect for a nonvanishing magnetic field. The
+presence of magnetic field also leads to a Hall type thermoelectric coefficient
+(Nernst coefficient) for the hot and dense hadronic matter apart from a
+magneto-Seebeck coefficient. We find that generically in the presence of a
+magnetic field Seebeck coefficient decreases while the Nernst coefficient
+increases with the magnetic field. At higher temperature and/or baryon chemical
+potential these coefficients approach to their values at vanishing magnetic
+field.",2004.04665v2
+2020-04-29,Large Fourier coefficients of half-integer weight modular forms,"This article is concerned with the Fourier coefficients of cusp forms (not
+necessarily eigenforms) of half-integer weight lying in the plus space. We give
+a soft proof that there are infinitely many fundamental discriminants $D$ such
+that the Fourier coefficients evaluated at $|D|$ are non-zero. By adapting the
+resonance method, we also demonstrate that such Fourier coefficients must take
+quite large values.",2004.14450v1
+2020-09-23,A combinatorial correspondence between finite Euclidean geometries and symmetric subsets of $\mathbb{Z}/n\mathbb{Z}$,"$q$-analogues of quantities in mathematics involve perturbations of classical
+quantities using the parameter $q$, and revert to the original quantities when
+$q$ goes $1$. An important example is the $q$-analogues of binomial
+coefficients which give the number of $k$-dimensional subspaces in
+$\mathbb{F}_{q}^{n}$. When $q$ goes to $1$, this reverts to the binomial
+coefficients which measure the number of $k$-sets in $\left [ n \right ]$.
+Dot-analogues of $q$-binomial coefficients were studied by Yoo (2019) in order
+to investigate combinatorics of quadratic spaces over finite fields. The number
+of $k$-dimensional quadratic spaces of
+$(\mathbb{F}_{q}^{n},x_{1}^{2}+x_{2}^{2}+\cdots+x_{n}^{2})$ which are
+isometrically isomorphic to
+$(\mathbb{F}_{q}^{k},x_{1}^{2}+x_{2}^{2}+\cdots+x_{k}^{2})$ can be also
+described as analogous to binomial coefficients, called the dot-binomial
+coefficients, $\binom{n}{k}_{d}$.
+  In this paper, we study a combinatorial correspondence between this finite
+Euclidean geometries and symmetric subsets of $\mathbb{Z}/n\mathbb{Z}$. In
+addition, we show that dot-binomial coefficients can be expressed in terms of
+$q$-binomial coefficients and polynomials, and we prove that dot-binomial
+coefficients are polynomials in $q$. Furthermore, we study the properties of
+the polynomials given by the dot binomial coefficients $\binom{n}{k}_{d}$.",2009.11258v2
+2020-11-21,Measuring Quadrangle Formation in Complex Networks,"The classic clustering coefficient and the lately proposed closure
+coefficient quantify the formation of triangles from two different
+perspectives, with the focal node at the centre or at the end in an open triad
+respectively. As many networks are naturally rich in triangles, they become
+standard metrics to describe and analyse networks. However, the advantages of
+applying them can be limited in networks, where there are relatively few
+triangles but which are rich in quadrangles, such as the protein-protein
+interaction networks, the neural networks and the food webs. This yields for
+other approaches that would leverage quadrangles in our journey to better
+understand local structures and their meaning in different types of networks.
+Here we propose two quadrangle coefficients, i.e., the i-quad coefficient and
+the o-quad coefficient, to quantify quadrangle formation in networks, and we
+further extend them to weighted networks. Through experiments on 16 networks
+from six different domains, we first reveal the density distribution of the two
+quadrangle coefficients, and then analyse their correlations with node degree.
+Finally, we demonstrate that at network-level, adding the average i-quad
+coefficient and the average o-quad coefficient leads to significant improvement
+in network classification, while at node-level, the i-quad and o-quad
+coefficients are useful features to improve link prediction.",2011.10763v1
+2021-05-20,On the $RO(Q)$-graded coefficients of Eilenberg-MacLane spectra,"Let $Q$ denote the cyclic group of order two. Using the Tate diagram we
+compute the $RO(Q)$-graded coefficients of Eilenberg-MacLane $Q$-spectra and
+describe their structure as a module over the coefficients of the
+Eilenberg-MacLane spectrum of the Burnside Mackey functor. If the underlying
+Mackey functor is a Green functor, we also infer the multiplicative structure
+on the $RO(Q)$-graded coefficients.",2105.09768v2
+2021-06-09,A Data-driven Optimization of First-order Regular Perturbation Coefficients for Fiber Nonlinearities,"We study the performance of gradient-descent optimization to estimate the
+coefficients of the discrete-time first-order regular perturbation (FRP). With
+respect to numerically computed coefficients, the optimized coefficients yield
+a model that (i) extends the FRP range of validity, and (ii) reduces the
+model's complexity.",2106.05088v2
+2021-09-05,Counting irreducible polynomials with prescribed coefficients over a finite field,"We continue our study on counting irreducible polynomials over a finite field
+with prescribed coefficients. We set up a general combinatorial framework using
+generating functions with coefficients from a group algebra which is generated
+by equivalent classes of polynomials with prescribed coefficients. Simplified
+expressions are derived for some special cases. Our results extend some earlier
+results.",2109.02000v1
+2022-02-17,High-Dimensional Time-Varying Coefficient Estimation,"In this paper, we develop a novel high-dimensional time-varying coefficient
+estimation method, based on high-dimensional Ito diffusion processes. To
+account for high-dimensional time-varying coefficients, we first estimate local
+(or instantaneous) coefficients using a time-localized Dantzig selection scheme
+under a sparsity condition, which results in biased local coefficient
+estimators due to the regularization. To handle the bias, we propose a
+debiasing scheme, which provides well-performing unbiased local coefficient
+estimators. With the unbiased local coefficient estimators, we estimate the
+integrated coefficient, and to further account for the sparsity of the
+coefficient process, we apply thresholding schemes. We call this Thresholding
+dEbiased Dantzig (TED). We establish asymptotic properties of the proposed TED
+estimator. In the empirical analysis, we apply the TED procedure to analyzing
+high-dimensional factor models using high-frequency data.",2202.08419v3
+2022-03-26,Fourier coefficients of Hilbert modular forms at cusps,"The aim of this article is to study the fields generated by the Fourier
+coefficients of Hilbert newforms at arbitrary cusps. Precisely, given a
+cuspidal Hilbert newform $f$ and a matrix $\sigma$ in (a suitable conjugate of)
+the Hilbert modular group, we give a cyclotomic extension of the field
+generated by the Fourier coefficients at infinity which contains all the
+Fourier coefficients of $f||_k\sigma$.",2203.14096v1
+2022-05-07,Bounds on the Total Coefficient Size of Nullstellensatz Proofs of the Pigeonhole Principle and the Ordering Principle,"In this paper, we investigate the total coefficient size of Nullstellensatz
+proofs. We show that Nullstellensatz proofs of the pigeonhole principle on $n$
+pigeons require total coefficient size $2^{\Omega(n)}$ and that there exist
+Nullstellensatz proofs of the ordering principle on $n$ elements with total
+coefficient size $2^n - n$.",2205.03577v1
+2022-05-09,Hypothesis testing for varying coefficient models in tail index regression,"This study examines the varying coefficient model in tail index regression.
+The varying coefficient model is an efficient semiparametric model that avoids
+the curse of dimensionality when including large covariates in the model. In
+fact, the varying coefficient model is useful in mean, quantile, and other
+regressions. The tail index regression is not an exception. However, the
+varying coefficient model is flexible, but leaner and simpler models are
+preferred for applications. Therefore, it is important to evaluate whether the
+estimated coefficient function varies significantly with covariates. If the
+effect of the non-linearity of the model is weak, the varying coefficient
+structure is reduced to a simpler model, such as a constant or zero.
+Accordingly, the hypothesis test for model assessment in the varying
+coefficient model has been discussed in mean and quantile regression. However,
+there are no results in tail index regression. In this study, we investigate
+the asymptotic properties of an estimator and provide a hypothesis testing
+method for varying coefficient models for tail index regression.",2205.04176v3
+2023-01-13,Li coefficients as norms of functions in a model space,"It is known that the nonnegativity of Li coefficients is a necessary and
+sufficient condition for the Riemann hypothesis. We show that it is a necessary
+and sufficient condition for the Riemann hypothesis that all Li coefficients
+are norms of certain concrete functions on the real line. Such conditional
+formulas for Li coefficients are understood as a kind of Weil's criterion for
+the Riemann hypothesis.",2301.05779v2
+2023-07-14,Computational progress on the unfair 0-1 polynomial Conjecture,"Let $c(x)$ be a monic integer polynomial with coefficients $0$ or $1$. Write
+$c(x) = a(x) b(x)$ where $a(x)$ and $b(x)$ are monic polynomials with
+non-negative real (not necessarily integer) coefficients. The unfair 0--1
+polynomial conjecture states that $a(x)$ and $b(x)$ are necessarily integer
+polynomials with coefficients $0$ or $1$. Let $a(x)$ be a candidate factor of a
+(currently unknown) 0--1 polynomial. We will assume that we know if a
+coefficient is $0$, $1$ or strictly between $0$ and $1$, but that we do not
+know the precise value of non-integer coefficients. Given this candidate
+$a(x)$, this paper gives an algorithm to either find a $b(x)$ and $c(x)$ with
+$a(x) b(x) = c(x)$ such that $b(x)$ has non-negative real coefficients and
+$c(x)$ has coefficients $0$ or $1$, or (often) shows that no such $c(x)$ and
+$b(x)$ exist. Using this algorithm, we consider all candidate factors with
+degree less than or equal to 15. With the exception of 975 candidate factors
+(out of a possible 7141686 cases), this algorithm shows that there do not exist
+$b(x)$ with non-negative real coefficients and $c(x)$ with coefficients $0$ or
+$1$ such that $a(x) b(x) = c(x)$.",2307.07363v1
+2023-09-27,Sharp Estimates on Coefficient functionals of Ozaki close-to-convex functions,"The goal of this manuscript to establish the best possible estimate on
+coefficient functionals like Hermitian-Toeplitz determinant of secoend order
+involving logarithmic coefficients, initial logarithmic inverse coefficients
+and initial order Schwarzian derivatives of the Ozaki close-to-convex
+functions.",2309.15927v1
+2023-10-24,Kronecker coefficients for (dual) symmetric inverse semigroups,"We study analogues of Kronecker coefficients for symmetric inverse
+semigroups, for dual symmetric inverse semigroups and for the inverse
+semigroups of bijections between subquotients of finite sets. In all cases we
+reduce the problem of determination of such coefficients to some
+group-theoretic and combinatorial problems. For symmetric inverse semigroups,
+we provide an explicit formula in terms of the classical Kronecker and
+Littlewood--Richardson coefficients for symmetric groups.",2310.15537v1
+2023-10-27,Data-scientific study of Kronecker coefficients,"We take a data-scientific approach to study whether Kronecker coefficients
+are zero or not. Motivated by principal component analysis and kernel methods,
+we define loadings of partitions and use them to describe a sufficient
+condition for Kronecker coefficients to be nonzero. The results provide new
+methods and perspectives for the study of these coefficients.",2310.17906v1
+2023-12-11,Hilbert Coefficients and Sally Modules: A Survey of Vasconcelos' Contributions,"This paper surveys and summarizes Wolmer Vasconcelos' results surrounding
+multiplicities, Hilbert coefficients, and their extensions. We particularly
+focus on Vasconcelos' results regarding multiplicities and Chern coefficients,
+and other invariants which they bound. The Sally module is an important
+instrument introduced by Vasconcelos for this study, which naturally relates
+Hilbert coefficients to reduction numbers.",2312.06846v1
+2024-01-05,Nonconvex High-Dimensional Time-Varying Coefficient Estimation for Noisy High-Frequency Observations,"In this paper, we propose a novel high-dimensional time-varying coefficient
+estimator for noisy high-frequency observations. In high-frequency finance, we
+often observe that noises dominate a signal of an underlying true process.
+Thus, we cannot apply usual regression procedures to analyze noisy
+high-frequency observations. To handle this issue, we first employ a smoothing
+method for the observed variables. However, the smoothed variables still
+contain non-negligible noises. To manage these non-negligible noises and the
+high dimensionality, we propose a nonconvex penalized regression method for
+each local coefficient. This method produces consistent but biased local
+coefficient estimators. To estimate the integrated coefficients, we propose a
+debiasing scheme and obtain a debiased integrated coefficient estimator using
+debiased local coefficient estimators. Then, to further account for the
+sparsity structure of the coefficients, we apply a thresholding scheme to the
+debiased integrated coefficient estimator. We call this scheme the Thresholded
+dEbiased Nonconvex LASSO (TEN-LASSO) estimator. Furthermore, this paper
+establishes the concentration properties of the TEN-LASSO estimator and
+discusses a nonconvex optimization algorithm.",2401.02694v1
+2014-11-28,"Heat kernel expansions, ambient metrics and conformal invariants","The conformal powers of the Laplacian of a Riemannian metric which are known
+as the GJMS-operators admit a combinatorial description in terms of the Taylor
+coefficients of a natural second-order one-parameter family $\H(r;g)$ of
+self-adjoint elliptic differential operators. $\H(r;g)$ is a non-Laplace-type
+perturbation of the conformal Laplacian $P_2(g) = \H(0;g)$. It is defined in
+terms of the metric $g$ and covariant derivatives of the curvature of $g$. We
+study the heat kernel coefficients $a_{2k}(r;g)$ of $\H(r;g)$ on closed
+manifolds. We prove general structural results for the heat kernel coefficients
+$a_{2k}(r;g)$ and derive explicit formulas for $a_0(r)$ and $a_2(r)$ in terms
+of renormalized volume coefficients. The Taylor coefficients of $a_{2k}(r;g)$
+(as functions of $r$) interpolate between the renormalized volume coefficients
+of a metric $g$ ($k=0$) and the heat kernel coefficients of the conformal
+Laplacian of $g$ ($r=0$). Although $\H(r;g)$ is not conformally covariant,
+there is a beautiful formula for the conformal variation of the trace of its
+heat kernel. As a consequence, we give a heat equation proof of the conformal
+transformation law of the integrated renormalized volume coefficients. By
+refining these arguments, we also give a heat equation proof of the conformal
+transformation law of the renormalized volume coefficients itself. The Taylor
+coefficients of $a_2(r)$ define a sequence of higher-order Riemannian curvature
+functionals with extremal properties at Einstein metrics which are analogous to
+those of integrated renormalized volume coefficients. Among the various
+additional results the reader finds a Polyakov-type formula for the
+renormalized volume of a Poincar\'e-Einstein metric in terms of $Q$-curvature
+of its conformal infinity and additional holographic terms.",1411.7851v1
+2015-06-17,Global clustering coefficient in scale-free weighted and unweighted networks,"In this paper, we present a detailed analysis of the global clustering
+coefficient in scale-free graphs. Many observed real-world networks of diverse
+nature have a power-law degree distribution. Moreover, the observed degree
+distribution usually has an infinite variance. Therefore, we are especially
+interested in such degree distributions. In addition, we analyze the clustering
+coefficient for both weighted and unweighted graphs.
+  There are two well-known definitions of the clustering coefficient of a
+graph: the global and the average local clustering coefficients. There are
+several models proposed in the literature for which the average local
+clustering coefficient tends to a positive constant as a graph grows. On the
+other hand, there are no models of scale-free networks with an infinite
+variance of the degree distribution and with an asymptotically constant global
+clustering coefficient. Models with constant global clustering and finite
+variance were also proposed. Therefore, in this paper we focus only on the most
+interesting case: we analyze the global clustering coefficient for graphs with
+an infinite variance of the degree distribution.
+  For unweighted graphs, we prove that the global clustering coefficient tends
+to zero with high probability and we also estimate the largest possible
+clustering coefficient for such graphs. On the contrary, for weighted graphs,
+the constant global clustering coefficient can be obtained even for the case of
+an infinite variance of the degree distribution.",1507.00925v1
+2015-10-07,Linear Bounds between Contraction Coefficients for $f$-Divergences,"Data processing inequalities for $f$-divergences can be sharpened using
+constants called ""contraction coefficients"" to produce strong data processing
+inequalities. For any discrete source-channel pair, the contraction
+coefficients for $f$-divergences are lower bounded by the contraction
+coefficient for $\chi^2$-divergence. In this paper, we elucidate that this
+lower bound can be achieved by driving the input $f$-divergences of the
+contraction coefficients to zero. Then, we establish a linear upper bound on
+the contraction coefficients for a certain class of $f$-divergences using the
+contraction coefficient for $\chi^2$-divergence, and refine this upper bound
+for the salient special case of Kullback-Leibler (KL) divergence. Furthermore,
+we present an alternative proof of the fact that the contraction coefficients
+for KL and $\chi^2$-divergences are equal for a Gaussian source with an
+additive Gaussian noise channel (where the former coefficient can be power
+constrained). Finally, we generalize the well-known result that contraction
+coefficients of channels (after extremizing over all possible sources) for all
+$f$-divergences with non-linear operator convex $f$ are equal. In particular,
+we prove that the so called ""less noisy"" preorder over channels can be
+equivalently characterized by any non-linear operator convex $f$-divergence.",1510.01844v4
+2021-03-03,"Generalized Collisional Fluid Theory for Multi-Component, Multi-Temperature Plasma Using The Linearized Boltzmann Collision Operator for Scrape-Off Layer/Edge Applications","Grad's method is used on the linearized Boltzmann collision operator to
+derive the most general expressions for the collision coefficients for a
+multi-component, multi-temperature plasma up to rank-2. In doing so, the
+collision coefficients then get expressed as series sum of pure coefficients of
+temperature and mass ratios multiplied by the cross-section dependent
+Chapman-Cowling integrals. These collisional coefficients are compared to
+previously obtained coefficients by Zhdanov et al [Zhdanov V.M., Transport
+processes in multi-component plasma, Taylor and Francis (2002)] for 13N-moment
+multi-temperature scheme. First, the differences in coefficients are compared
+directly, and then the differences in first approximation to viscosity and
+friction force are compared. For the 13N-moment multi-temperature coefficients,
+it is found that they behave reasonably similarly for small temperature
+differences, but display substantial differences in the coefficients when the
+temperature differences are high, both for the coefficients and for viscosity
+and friction force values. Furthermore, the obtained coefficients are compared
+to the 21N-moment single-temperature approximation provided by Zhdanov et al,
+and it is seen that the differences are higher than the 13N-moment
+multi-temperature coefficients, and have substantial differences even in the
+vicinity of equal temperatures, especially for the viscosity and friction force
+calculations.",2103.02455v3
+2022-01-31,GenMod: A generative modeling approach for spectral representation of PDEs with random inputs,"We propose a method for quantifying uncertainty in high-dimensional PDE
+systems with random parameters, where the number of solution evaluations is
+small. Parametric PDE solutions are often approximated using a spectral
+decomposition based on polynomial chaos expansions. For the class of systems we
+consider (i.e., high dimensional with limited solution evaluations) the
+coefficients are given by an underdetermined linear system in a regression
+formulation. This implies additional assumptions, such as sparsity of the
+coefficient vector, are needed to approximate the solution. Here, we present an
+approach where we assume the coefficients are close to the range of a
+generative model that maps from a low to a high dimensional space of
+coefficients. Our approach is inspired be recent work examining how generative
+models can be used for compressed sensing in systems with random Gaussian
+measurement matrices. Using results from PDE theory on coefficient decay rates,
+we construct an explicit generative model that predicts the polynomial chaos
+coefficient magnitudes. The algorithm we developed to find the coefficients,
+which we call GenMod, is composed of two main steps. First, we predict the
+coefficient signs using Orthogonal Matching Pursuit. Then, we assume the
+coefficients are within a sparse deviation from the range of a sign-adjusted
+generative model. This allows us to find the coefficients by solving a
+nonconvex optimization problem, over the input space of the generative model
+and the space of sparse vectors. We obtain theoretical recovery results for a
+Lipschitz continuous generative model and for a more specific generative model,
+based on coefficient decay rate bounds. We examine three high-dimensional
+problems and show that, for all three examples, the generative model approach
+outperforms sparsity promoting methods at small sample sizes.",2201.12973v1
+2022-07-14,Homology and cohomology of cubical sets with coefficients in systems of objects,"This paper continues the research of the author on the homology of cubical
+and semi-cubical sets with coefficients in systems of objects. The main result
+is the theorem that the homology of cubical sets with coefficients in
+contravariant systems in an Abelian category with exact coproducts is
+isomorphic to the left satellites of a colimit functor. This made it possible
+to prove a number of the following new assertions, presented in the paper,
+about the homology and cohomology of cubical sets with coefficients in systems
+of objects. These homology are invariant under morphism between cubical sets
+when passing to the direct image of the system of coefficients. There is a
+criterion for the invariance of these homologies when passing to the inverse
+image. These homology generalize the singular cubical homology with local
+coefficients and the homology of semi-cubical sets with coefficients in
+contravariant systems. There is a spectral sequence for colimit homologies of
+cubical sets with coefficients in contravariant systems. The weak equivalence
+of cubical sets induces an isomorphism of homology with local systems. For a
+morphism of cubical sets whose inverse fiber morphisms are weak equivalences,
+there exists a spectral sequence for homology with local systems converging to
+the homology of the domain of this morphism. The homology of small category
+with coefficients in a diagram can be calculated as cubical homology. The
+Baues-Wirsching cohomologies with coefficients in natural systems are
+isomorphic to cubical cohomologies with coefficients in covariant systems.",2207.07233v6
+2023-01-02,Sample-to-sample fluctuations of transport coefficients in the totally asymmetric simple exclusion process with quenched disorder,"We consider the totally asymmetric simple exclusion processes on quenched
+random energy landscapes. We show that the current and the diffusion
+coefficient differ from those for homogeneous environments. Using the
+mean-field approximation, we analytically obtain the site density when the
+particle density is low or high. As a result, the current and the diffusion
+coefficient are described by the dilute limit of particles or holes,
+respectively. However, in the intermediate regime, due to the many-body effect,
+the current and the diffusion coefficient differ from those for single-particle
+dynamics. The current is almost constant and becomes the maximal value in the
+intermediate regime. Moreover, the diffusion coefficient decreases with the
+particle density in the intermediate regime. We obtain analytical expressions
+for the maximal current and the diffusion coefficient based on the renewal
+theory. The deepest energy depth plays a central role in determining the
+maximal current and the diffusion coefficient. As a result, the maximal current
+and the diffusion coefficient depend crucially on the disorder, i.e.,
+non-self-averaging. Based on the extreme value theory, we find that
+sample-to-sample fluctuations of the maximal current and diffusion coefficient
+are characterized by the Weibull distribution. We show that the disorder
+averages of the maximal current and the diffusion coefficient converge to zero
+as the system size is increased and quantify the degree of the
+non-self-averaging effect for the maximal current and the diffusion
+coefficient.",2301.00563v3
+2024-03-12,Preconditioners based on Voronoi quantizers of random variable coefficients for stochastic elliptic partial differential equations,"A preconditioning strategy is proposed for the iterative solve of large
+numbers of linear systems with variable matrix and right-hand side which arise
+during the computation of solution statistics of stochastic elliptic partial
+differential equations with random variable coefficients sampled by Monte
+Carlo. Building on the assumption that a truncated Karhunen-Lo\`{e}ve expansion
+of a known transform of the random variable coefficient is known, we introduce
+a compact representation of the random coefficient in the form of a Voronoi
+quantizer. The number of Voronoi cells, each of which is represented by a
+centroidal variable coefficient, is set to the prescribed number $P$ of
+preconditioners. Upon sampling the random variable coefficient, the linear
+system assembled with a given realization of the coefficient is solved with the
+preconditioner whose centroidal variable coefficient is the closest to the
+realization. We consider different ways to define and obtain the centroidal
+variable coefficients, and we investigate the properties of the induced
+preconditioning strategies in terms of average number of solver iterations for
+sequential simulations, and of load balancing for parallel simulations. Another
+approach, which is based on deterministic grids on the system of stochastic
+coordinates of the truncated representation of the random variable coefficient,
+is proposed with a stochastic dimension which increases with the number $P$ of
+preconditioners. This approach allows to bypass the need for preliminary
+computations in order to determine the optimal stochastic dimension of the
+truncated approximation of the random variable coefficient for a given number
+of preconditioners.",2403.07824v1
+2003-01-10,Hydrodynamics and transport coefficients for Granular Gases,"The hydrodynamics of granular gases of viscoelastic particles, whose
+collision is described by an impact-velocity dependent coefficient of
+restitution, is developed using a modified Chapman-Enskog approach. We derive
+the hydrodynamic equations and the according transport coefficients with the
+assumption that the shape of the velocity distribution function follows
+adiabatically the decaying temperature. We show numerically that this
+approximation is justified up to intermediate dissipation. The transport
+coefficients and the coefficient of cooling are expressed in terms of the
+elastic and dissipative parameters of the particle material and by the gas
+parameters. The dependence of these coefficients on temperature differs
+qualitatively from that obtained with the simplifying assumption of a constant
+coefficient of restitution which was used in previous studies. The approach
+formulated for gases of viscoelastic particles may be applied also for other
+impact-velocity dependencies of the restitution coefficient.",0301152v1
+1992-12-26,Unimodality of generalized Gaussian coefficients,"A combinatorial proof of the unimodality of the generalized q-Gaussian
+coefficients based on the explicit formula for Kostka-Foulkes polynomials is
+given.",9212152v1
+2005-02-19,When a C*-algebra is a coefficient algebra for a given endomorphism,"The paper presents a criterion for a C*-algebra to be a coefficient algebra
+associated with a given endomorphism",0502414v1
+2008-01-04,Borg type uniqueness Theorems for periodic Jacobi operators with matrix valued coefficients,"We give a simple proof of Borg type uniqueness Theorems for periodic Jacobi
+operators with matrix valued coefficients.",0801.0687v1
+2008-08-11,"Apery, Bessel, Calabi-Yau and Verrill","A differential equation related to the moments of Bessel functions is shown
+to have a solution at infinity with coefficients being squares of binomial
+coefficients.",0808.1480v1
+2008-12-04,Quasipolynomial formulas for the Kronecker coefficients indexed by two two-row shapes (extended abstract),"We show that the Kronecker coefficients (the Clebsch-Gordan coefficients of
+the symmetric group) indexed by two two-row shapes are given by quadratic
+quasipolynomial formulas whose domains are the maximal cells of a fan. Simple
+calculations provide explicitly the quasipolynomial formulas and a description
+of the associated fan.
+  These new formulas are obtained from analogous formulas for the corresponding
+reduced Kronecker coefficients and a formula recovering the Kronecker
+coefficients from the reduced Kronecker coefficients.
+  As an application, we characterize all the Kronecker coefficients indexed by
+two two-row shapes that are equal to zero. This allowed us to disprove a
+conjecture of Mulmuley about the behavior of the stretching functions attached
+to the Kronecker coefficients.",0812.0861v1
+2009-01-11,"Counting Bipartite, k-Colored and Directed Acyclic Multi Graphs Through F-nomial coefficients","F-nomial coefficients encompass among others well-known binomial coefficients
+or Gaussian coefficients that count subsets of finite set and subspaces of
+finite vector space respectively. Here, the so called F-cobweb tiling sequences
+N(a) are considered. For such specific sequences a new interpretation with
+respect to Kwasniewski general combinatorial interpretation of F-nomial
+coefficients is unearhed.
+  Namely, for tiling sequences F = N(a)$ the F-nomial coefficients are equal to
+the number of labeled special bipartite multigraphs denoted here as
+a-multigraphs G(a,n,k).
+  An explicit relation between the number of k-colored a-multigraphs and multi
+N(a)-nomial coefficients is established. We also prove that the unsigned values
+of the first row of inversion matrix for N(a) -nomial coefficients considered
+here are equal to the numbers of directed acyclic a-multigraphs with n nodes.",0901.1337v1
+2010-06-01,Second-order linear constant coefficient dynamic equations with polynomial forcing on time scales,"A general solution for a second-order linear constant coefficient dynamic
+equation with polynomial forcing on time scales is given.",1006.0074v1
+2010-06-15,Some congruences for trinomial coefficients,We prove several congruences for trinomial coefficients.,1006.3025v2
+2010-08-13,Flexible Shrinkage Estimation in High-Dimensional Varying Coefficient Models,"We consider the problem of simultaneous variable selection and constant
+coefficient identification in high-dimensional varying coefficient models based
+on B-spline basis expansion. Both objectives can be considered as some type of
+model selection problems and we show that they can be achieved by a double
+shrinkage strategy. We apply the adaptive group Lasso penalty in models
+involving a diverging number of covariates, which can be much larger than the
+sample size, but we assume the number of relevant variables is smaller than the
+sample size via model sparsity. Such so-called ultra-high dimensional settings
+are especially challenging in semiparametric models as we consider here and has
+not been dealt with before. Under suitable conditions, we show that consistency
+in terms of both variable selection and constant coefficient identification can
+be achieved, as well as the oracle property of the constant coefficients. Even
+in the case that the zero and constant coefficients are known a priori, our
+results appear to be new in that it reduces to semivarying coefficient models
+(a.k.a. partially linear varying coefficient models) with a diverging number of
+covariates. We also theoretically demonstrate the consistency of a
+semiparametric BIC-type criterion in this high-dimensional context, extending
+several previous results. The finite sample behavior of the estimator is
+evaluated by some Monte Carlo studies.",1008.2271v1
+2010-11-26,Idempotents with polynomial coefficients,"We combine Young idempotents in the group algebra of the symmetric group with
+the action of the symmetric group on products of Vandermonde determinants to
+obtain idempotents with polynomial coefficients.",1011.5815v1
+2011-04-29,Closed string transport coefficients and the membrane paradigm,"I discuss a correspondence between a fictitious fluid in the black hole
+membrane paradigm and highly excited closed string states according to the
+black hole correspondence principle. I calculate the membrane transport
+coefficients of an electric NS-NS 2-charged black hole and transport
+coefficients of the highly excited closed string states which possess a
+Kaluza-Klein number and a winding number. Comparing both the transport
+coefficients at the correspondence point, I show that, except for the bulk
+viscosity, the membrane transport coefficients are of the same order as the
+transport coefficients of the closed string states on the stretched horizon.
+Also, I show that, except for the bulk viscosity, both the dimensionless
+transport coefficients, which are defined by dividing the transport
+coefficients by the entropy density, are exactly equal if the central charge is
+6.",1104.5556v3
+2011-09-26,Logarithmic vector-valued modular forms and polynomial-growth estimates of their Fourier coefficients,"We establish (Theorem 3.6) polynomial-growth estimates for the
+  Fourier coefficients of holomorphic logarithmic vector-valued modular forms.",1109.5740v1
+2012-02-13,Steiner symmetrization and the initial coefficients of univalent functions,"We study the behavior of the initial coefficients of univalent functions
+under the Steiner symmetrization, and give some applications to functions of
+class \Sigma.",1202.2633v1
+2012-03-26,On the Boundedness of Solutions of a Rational System with a Variable Coefficient,"We establish the boundedness character of solutions of a system of rational
+difference equations with a variable coefficient",1203.5770v1
+2012-06-22,Smoothing estimates for variable coefficients Schroedinger equation with electromagnetic potentials,"In this paper we develop the classical multiplier technique to prove a virial
+identity and smoothing estimates (in a perturbative setting) for the
+electromagnetic variable coefficients Schroedinger equation.",1206.5177v1
+2013-06-02,Derivation of the coefficient squared probability law in quantum mechanics,"If one assumes there is probability of perception in quantum mechanics, then
+unitarity dictates that it must have the coefficient squared form, in agreement
+with experiment.",1306.0213v1
+2014-03-26,Extraction of the symmetry energy coefficients from the masses differences of isobaric nuclei,"The nuclear symmetry energy coefficients of finite nuclei are extracted by
+using the differences between the masses of isobaric nuclei. Based on the
+masses of more than 2400 nuclei with $A=9-270$, we investigate the model
+dependence in the extraction of symmetry energy coefficient. We find that the
+extraction of the symmetry energy coefficients is strongly correlated with the
+forms of the Coulomb energy and the mass dependence of the symmetry energy
+coefficient adopted. The values of the extracted symmetry energy coefficients
+increase by about 2 MeV for heavy nuclei when the Coulomb correction term is
+involved. We obtain the bulk symmetry energy coefficient $S_0=28.26\pm1.3$ MeV
+and the surface-to-volume ratio $\kappa=1.26\pm 0.25 $ MeV if assuming the mass
+dependence of symmetry energy coefficient $a_{\rm
+sym}(A)=S_0(1-\kappa/A^{1/3})$, and $S_0=32.80\pm1.7$ MeV, $\kappa=2.82\pm0.57$
+MeV when $a_{\rm sym}(A)=S_0 (1+\kappa/A^{1/3})^{-1}$ is adopted.",1403.6560v2
+2014-09-16,Distribution of zeros of polynomials with positive coefficients,"We describe the limit zero distributions of sequences of polynomials with
+positive coefficients.",1409.4640v1
+2014-11-29,Continuous and robust clustering coefficients for weighted and directed networks,"We introduce new clustering coefficients for weighted networks. They are
+continuous and robust against edge weight changes. Recently, generalized
+clustering coefficients for weighted and directed networks have been proposed.
+These generalizations have a common property, that their values are not
+continuous. They are sensitive with edge weight changes, especially at zero
+weight. With these generalizations, if vanishingly low weights of edges are
+truncated to weight zero for some reason, the coefficient value may change
+significantly from the original value. It is preferable that small changes of
+edge weights cause small changes of coefficient value. We call this property
+the continuity of generalized clustering coefficients. Our new coefficients
+admit this property. In the past, few studies have focused on the continuity of
+generalized clustering coefficients. In experiments, we performed comparative
+assessments of existing and our generalizations. In the case of a real world
+network dataset (C. Elegans Neural network), after adding random edge weight
+errors, though the value of one discontinuous generalization was changed about
+436%, the value of proposed one was only changed 0.2%.",1412.0059v1
+2016-02-13,Fast Computation of the Kinship Coefficients,"For families, kinship coefficients are quantifications of the amount of
+genetic sharing between a pair of individuals. These coefficients are critical
+for understanding the breeding habits and genetic diversity of diploid
+populations. Historically, computations of the inbreeding coefficient were used
+to prohibit inbred marriages and prohibit breeding of some pairs of pedigree
+animals. Such prohibitions foster genetic diversity and help prevent recessive
+Mendelian disease at a population level.
+  This paper gives the fastest known algorithms for computing the kinship
+coefficient of a set of individuals with a known pedigree. The algorithms given
+here consider the possibility that the founders of the known pedigree may
+themselves be inbred, and they compute the appropriate inbreeding-adjusted
+kinship coefficients. The exact kinship algorithm has running-time $O(n^2)$ for
+an $n$-individual pedigree. The recursive-cut exact kinship algorithm has
+running time $O(s^2m)$ where $s$ is the number of individuals in the largest
+segment of the pedigree and $m$ is the number of cuts. The approximate
+algorithm has running-time $O(n)$ for an $n$-individual pedigree on which to
+estimate the kinship coefficients of $\sqrt{n}$ individuals from $\sqrt{n}$
+founder kinship coefficients.",1602.04368v1
+2016-03-31,Improved bounds for Fourier coefficients of Siegel modular forms,"The goal of this paper is to improve existing bounds for Fourier coefficients
+of higher genus Siegel modular forms of small weight.",1603.09556v1
+2016-05-02,On the $C^1$ regularity of solutions to divergence form elliptic systems with Dini-continuous coefficients,"We prove $C^1$ regularity of solutions to divergence form elliptic systems
+with Dini-continuous coefficients",1605.00535v1
+2016-06-15,Modal analysis of the scattering coefficients of an open cavity in a waveguide,"The characteristics of an acoustic scatterer are often described by
+scattering coefficients. The understanding of the mechanisms involved in the
+frequency dependent features of the coefficients has been a challenge task,
+owing to the complicated coupling between the waves in open space and the modes
+inside the finite scatterer. In this paper, a frequency-dependent modal
+description of the scattering coefficient is utilized to study the modal
+properties of the scatterer. The important role that eigenmodes play in
+defining the features of the scattering coefficients is revealed via an
+expansion of the coefficients by the eigenmodes. The results show the local
+extrema of the scattering coefficients can be attributed to the
+constructive/destructive interference of resonant and non-resonant modes. In
+particular, an approximated equation, which is equivalent to the standard Fano
+formula, is obtained to describe the sharp anti-symmetric Fano characteristics
+of the scattering coefficients. The special cases where scattering is dominated
+by a single resonance eigenmode, corresponding to the ""resonance transmission"",
+are also illustrated.",1606.05676v1
+2016-09-17,Convolution identities for Tetranacci numbers,"We give convolution identities without binomial coefficients for Tetranacci
+numbers and convolution identities with binomial coefficients for Tetranacci
+and Tetranacci-type numbers.",1609.05272v1
+2016-11-29,Strictly Hyperbolic Equations with Coefficients Low-Regular in Time and Smooth in Space,"We consider the Cauchy problem for strictly hyperbolic $m$-th order partial
+differential equations with coefficients low-regular in time and smooth in
+space. It is well-known that the problem is $L^2$ well-posed in the case of
+Lipschitz continuous coefficients in time, $H^s$ well-posed in the case of
+Log-Lipschitz continuous coefficients in time (with an, in general, finite loss
+of derivatives) and Gevrey well-posed in the case of H\""older continuous
+coefficients in time (with an, in general, infinite loss of derivatives). Here,
+we use moduli of continuity to describe the regularity of the coefficients with
+respect to time, weight sequences for the characterization of their regularity
+with respect to space and weight functions to define the solution spaces. We
+establish sufficient conditions for the well-posedness of the Cauchy problem,
+that link the modulus of continuity and the weight sequence of the coefficients
+to the weight function of the solution space. The well-known results for
+Lipschitz, Log-Lipschitz and H\""older coefficients are recovered.",1611.09548v2
+2017-01-22,Some divisibility properties of binomial coefficients,"In this paper, we gave some properties of binomial coefficient.",1701.06217v1
+2017-01-30,Bounds on Distance to Variety in Terms of Coefficients of Bivariate Polynomials,"A short note on bounds on distance to variety of a point in terms of the
+Taylor coefficients at the point.",1701.08613v1
+2017-02-22,Simultaneous determination of the drift and diffusion coefficients in stochastic differential equations,"In this work, we consider a one-dimensional It{\^o} diffusion process X t
+with possibly nonlinear drift and diffusion coefficients. We show that, when
+the diffusion coefficient is known, the drift coefficient is uniquely
+determined by an observation of the expectation of the process during a small
+time interval, and starting from values X 0 in a given subset of R. With the
+same type of observation, and given the drift coefficient, we also show that
+the diffusion coefficient is uniquely determined. When both coefficients are
+unknown, we show that they are simultaneously uniquely determined by the
+observation of the expectation and variance of the process, during a small time
+interval, and starting again from values X 0 in a given subset of R. To derive
+these results, we apply the Feynman-Kac theorem which leads to a linear
+parabolic equation with unknown coefficients in front of the first and second
+order terms. We then solve the corresponding inverse problem with PDE technics
+which are mainly based on the strong parabolic maximum principle.",1702.06859v1
+2017-08-05,Optimization of Non Binary Parity Check Coefficients,"This paper generalizes the method proposed by Poulliat et al. for the
+determination of the optimal Galois Field coefficients of a Non-Binary LDPC
+parity check constraint based on the binary image of the code. Optimal, or
+almost-optimal, parity check coefficients are given for check degree varying
+from 4 to 20 and Galois Field varying from GF(64) up to GF(1024). For all given
+sets of coefficients, no codeword of Hamming weight two exists. A reduced
+complexity algorithm to compute the binary Hamming weight 3 of a parity check
+is proposed. When the number of sets of coefficients is too high for an
+exhaustive search and evaluation, a local greedy search is performed. Explicit
+tables of coefficients are given. The proposed sets of coefficients can
+effectively replace the random selection of coefficients often used in NB-LDPC
+construction.",1708.01761v2
+2017-09-12,Elementary proof of congruences involving sum of binomial coefficients,"We provide elementary proof of several congruences involving single sum and
+multisums of binomial coefficients.",1709.04039v2
+2018-01-03,Local Coefficients Revisited,"Two simple ""simplicial approximation"" tricks are invoked to prove basic
+results involving (co)-homology with local coefficients.",1801.01148v1
+2018-05-29,"Properties of interaction networks, structure coefficients, and benefit-to-cost ratios","In structured populations the spatial arrangement of cooperators and
+defectors on the interaction graph together with the structure of the graph
+itself determines the game dynamics and particularly whether or not fixation of
+cooperation (or defection) is favored. For a single cooperator (and a single
+defector) and a network described by a regular graph the question of fixation
+can be addressed by a single parameter, the structure coefficient. As this
+quantity is generic for any regular graph, we may call it the generic structure
+coefficient. For two and more cooperators (or several defectors) fixation
+properties can also be assigned by structure coefficients. These structure
+coefficients, however, depend on the arrangement of cooperators and defectors
+which we may interpret as a configuration of the game. Moreover, the
+coefficients are specific for a given interaction network modeled as regular
+graph, which is why we may call them specific structure coefficients. In this
+paper, we study how specific structure coefficients vary over interaction
+graphs and link the distributions obtained over different graphs to spectral
+properties of interaction networks. We also discuss implications for the
+benefit-to-cost ratios of donation games.",1805.11359v2
+2018-10-06,Large Eddy Simulation of a NACA0015 Circulation Control Airfoil Using Synthetic Jets,"Large eddy simulation of a NACA0015 circulation control airfoil using
+synthetic jets is conducted. A chord Reynolds number of 110000, the excitation
+frequency of 175 Hz, the momentum coefficients of 0.0044 to 0.0688, and the
+angles of attack of 0{\deg}, 6{\deg}, and 12{\deg} are employed in this study.
+The numerical results presented in this paper show good agreement with the
+experimental results. Fluctuations in the lift and drag coefficients on the
+non-actuated airfoil are found to be governed by the vortex shedding frequency.
+Provided that the momentum coefficient is sufficiently high, the lift and drag
+coefficients tend to fluctuate at the synthetic jet frequency. The mean lift
+coefficient linearly increases with the momentum coefficient at a low momentum
+coefficient range and its incremental rate begins to decline at a high momentum
+coefficient range. Increasing the angle of attack of the airfoil is observed to
+slightly reduce the slope of the lift increment.",1810.02914v1
+2018-12-03,Recursion Relations in Witten Diagrams and Conformal Partial Waves,"We revisit the problem of performing conformal block decomposition of
+exchange Witten diagrams in the crossed channel. Using properties of conformal
+blocks and Witten diagrams, we discover infinitely many linear relations among
+the crossed channel decomposition coefficients. These relations allow us to
+formulate a recursive algorithm that solves the decomposition coefficients in
+terms of certain seed coefficients. In one dimensional CFTs, the seed
+coefficient is the decomposition coefficient of the double-trace operator with
+the lowest conformal dimension. In higher dimensions, the seed coefficients are
+the coefficients of the double-trace operators with the minimal conformal
+twist. We also discuss the conformal block decomposition of a generic contact
+Witten diagram with any number of derivatives. As a byproduct of our analysis,
+we obtain a similar recursive algorithm for decomposing conformal partial waves
+in the crossed channel.",1812.01006v3
+2019-02-07,Recovering time-dependent singular coefficients of the wave-equation-One Dimensional Case,"We give a way to recover time-dependent singular coefficients of the
+wave-equation in the one-dimensional case.",1902.02619v1
+2019-04-15,Fast Inference in Capsule Networks Using Accumulated Routing Coefficients,"We present a method for fast inference in Capsule Networks (CapsNets) by
+taking advantage of a key insight regarding the routing coefficients that link
+capsules between adjacent network layers. Since the routing coefficients are
+responsible for assigning object parts to wholes, and an object whole generally
+contains similar intra-class and dissimilar inter-class parts, the routing
+coefficients tend to form a unique signature for each object class. For fast
+inference, a network is first trained in the usual manner using examples from
+the training dataset. Afterward, the routing coefficients associated with the
+training examples are accumulated offline and used to create a set of ""master""
+routing coefficients. During inference, these master routing coefficients are
+used in place of the dynamically calculated routing coefficients. Our method
+effectively replaces the for-loop iterations in the dynamic routing procedure
+with a single matrix multiply operation, providing a significant boost in
+inference speed. Compared with the dynamic routing procedure, fast inference
+decreases the test accuracy for the MNIST, Background MNIST, Fashion MNIST, and
+Rotated MNIST datasets by less than 0.5% and by approximately 5% for CIFAR10.",1904.07304v1
+2019-06-08,Frequency-Dependent Perceptual Quantisation for Visually Lossless Compression Applications,"The default quantisation algorithms in the state-of-the-art High Efficiency
+Video Coding (HEVC) standard, namely Uniform Reconstruction Quantisation (URQ)
+and Rate-Distortion Optimised Quantisation (RDOQ), do not take into account the
+perceptual relevance of individual transform coefficients. In this paper, a
+Frequency-Dependent Perceptual Quantisation (FDPQ) technique for HEVC is
+proposed. FDPQ exploits the well-established Modulation Transfer Function (MTF)
+characteristics of the linear transformation basis functions by taking into
+account the Euclidean distance of an AC transform coefficient from the DC
+coefficient. As such, in luma and chroma Cb and Cr Transform Blocks (TBs), FDPQ
+quantises more coarsely the least perceptually relevant transform coefficients
+(i.e., the high frequency AC coefficients). Conversely, FDPQ preserves the
+integrity of the DC coefficient and the very low frequency AC coefficients.
+Compared with RDOQ, which is the most widely used transform coefficient-level
+quantisation technique in video coding, FDPQ successfully achieves bitrate
+reductions of up to 41%. Furthermore, the subjective evaluations confirm that
+the FDPQ-coded video data is perceptually indistinguishable (i.e., visually
+lossless) from the raw video data for a given Quantisation Parameter (QP).",1906.03395v1
+2019-09-05,Frieze patterns with coefficients,"Frieze patterns, as introduced by Coxeter in the 1970's, are closely related
+to cluster algebras without coefficients. A suitable generalization of frieze
+patterns, linked to cluster algebras with coefficients, has only briefly
+appeared in an unpublished manuscript by Propp. In this paper we study these
+frieze patterns with coefficients systematically and prove various fundamental
+results, generalizing classic results for frieze patterns. As a consequence we
+see how frieze patterns with coefficients can be obtained from classic frieze
+patterns by cutting out subpolygons from the triangulated polygons associated
+to classic Conway-Coxeter frieze patterns. We address the question of which
+frieze patterns with coefficients can be obtained in this way and solve this
+problem completely for triangles. Finally, we prove a finiteness result for
+frieze patterns with coefficients by showing that for a given boundary sequence
+there are only finitely many (non-zero) frieze patterns with coefficients with
+entries in a discrete subset of the complex numbers.",1909.02332v1
+2019-09-12,Sharp Large Deviations for empirical correlation coefficients,"We study Sharp Large Deviations for Pearson's empirical correlation
+coefficients in the Spherical and Gaussian cases",1909.05570v1
+2019-10-28,Accurate calculation of field expansion coefficients in FEM magnetostatic simulations,"FEM simulations are a standard step in the design of accelerator magnets. It
+is custom for accelerator applications to characterize the field quality in
+terms of field expansion coefficients. With a commonly accepted approach,
+expansion coefficients are calculated by means of a Fourier transform of the
+local FEM solution at points on an arc. The accuracy of the coefficients
+calculated this way depends strongly on the FEM mesh configuration and simple
+refinement of the mesh does not always improve accuracy. The accuracy of the
+expansion coefficients calculation can be improved by using the data on the
+magnetization of elements in the magnet yoke, obtained in the solution, instead
+of using directly the local solution. Since currents and the yoke magnetization
+are the only sources of the field, with these data the field expansion
+coefficients can be calculated at any remote point. We derive closed forms for
+calculating expansion coefficients and implemented these results in the ANSYS
+add-on. Results for a case study are presented, which demonstrate that
+expansion coefficients can be calculated with good accuracy even for a rather
+coarse mesh.",1910.12696v1
+2019-11-26,Closure coefficients in scale-free complex networks,"The formation of triangles in complex networks is an important network
+property that has received tremendous attention. The formation of triangles is
+often studied through the clustering coefficient. The closure coefficient or
+transitivity is another method to measure triadic closure. This statistic
+measures clustering from the head node of a triangle (instead of from the
+center node, as in the often studied clustering coefficient). We perform a
+first exploratory analysis of the behavior of the local closure coefficient in
+two random graph models that create simple networks with power-law degrees: the
+hidden-variable model and the hyperbolic random graph. We show that the closure
+coefficient behaves significantly different in these simple random graph models
+than in the previously studied multigraph models. We also relate the closure
+coefficient of high-degree vertices to the clustering coefficient and the
+average nearest neighbor degree.",1911.11410v2
+2020-02-28,The third logarithmic coefficient for the class S,"In this paper we give an upper bound of the third logarithmic coefficient for
+the class $\mathcal{S}$ of univalent functions in the unit disc.",2002.12865v1
+2020-04-29,Eulerianity of Fourier coefficients of automorphic forms,"We study the question of Eulerianity (factorizability) for Fourier
+coefficients of automorphic forms, and we prove a general transfer theorem that
+allows one to deduce the Eulerianity of certain coefficients from that of
+another coefficient. We also establish a `hidden' invariance property of
+Fourier coefficients. We apply these results to minimal and next-to-minimal
+automorphic representations, and deduce Eulerianity for a large class of
+Fourier and Fourier-Jacobi coefficients. In particular, we prove Eulerianity
+for parabolic Fourier coefficients with characters of maximal rank for a class
+of Eisenstein series in minimal and next-to-minimal representations of groups
+of ADE-type that are of interest in string theory.",2004.14244v3
+2021-01-19,A survey on the theory of multiple Dirichlet series with arithmetical coefficients on the numerators,"We survey some recent developments in the analytic theory of multiple
+Dirichlet series with arithmetical coefficients on the numerators.",2101.07449v1
+2021-03-02,Power series with inverse binomial coefficients and harmonic numbers,"We construct the generating function for products of inverse central binomial
+coefficients with harmonic numbers.",2103.01879v1
+2021-07-16,Geometric Value Iteration: Dynamic Error-Aware KL Regularization for Reinforcement Learning,"The recent boom in the literature on entropy-regularized reinforcement
+learning (RL) approaches reveals that Kullback-Leibler (KL) regularization
+brings advantages to RL algorithms by canceling out errors under mild
+assumptions. However, existing analyses focus on fixed regularization with a
+constant weighting coefficient and do not consider cases where the coefficient
+is allowed to change dynamically. In this paper, we study the dynamic
+coefficient scheme and present the first asymptotic error bound. Based on the
+dynamic coefficient error bound, we propose an effective scheme to tune the
+coefficient according to the magnitude of error in favor of more robust
+learning. Complementing this development, we propose a novel algorithm,
+Geometric Value Iteration (GVI), that features a dynamic error-aware KL
+coefficient design with the aim of mitigating the impact of errors on
+performance. Our experiments demonstrate that GVI can effectively exploit the
+trade-off between learning speed and robustness over uniform averaging of a
+constant KL coefficient. The combination of GVI and deep networks shows stable
+learning behavior even in the absence of a target network, where algorithms
+with a constant KL coefficient would greatly oscillate or even fail to
+converge.",2107.07659v2
+2021-07-21,A closed formula of Littlewood-Richardson coefficients,We give a closed formula of the Littlewood-Richardson coefficients.,2107.09907v2
+2021-11-02,On the $RO(G)$-graded coefficients of $Q_8$ equivariant cohomology,"In this paper, we calculate the $RO(G)$-graded coefficients of
+$H\underline{\mathbb{Z}}$, the Eilenberg-MacLane spectrum of constant Mackey
+functor for quaternion group $Q_8$.",2111.01926v1
+2021-11-19,Fibonacci Identities Involving Reciprocals of Binomial Coefficients,"We derive some Fibonacci and Lucas identities which contain inverse binomial
+coefficients. Extension of the results to the general Horadam sequence is
+possible, in some cases.",2112.00622v1
+2022-04-05,"Existence, uniqueness and approximation of solutions of SDEs with superlinear coefficients in the presence of discontinuities of the drift coefficient","Existence, uniqueness, and $L_p$-approximation results are presented for
+scalar stochastic differential equations (SDEs) by considering the case where,
+the drift coefficient has finitely many spatial discontinuities while both
+coefficients can grow superlinearly (in the space variable). These
+discontinuities are described by a piecewise local Lipschitz continuity and a
+piecewise monotone-type condition while the diffusion coefficient is assumed to
+be locally Lipschitz continuous and non-degenerate at the discontinuity points
+of the drift coefficient. Moreover, the superlinear nature of the coefficients
+is dictated by a suitable coercivity condition and a polynomial growth of the
+(local) Lipschitz constants of the coefficients. Existence and uniqueness of
+strong solutions of such SDEs are obtained. Furthermore, the classical
+$L_p$-error rate $1/2$, for a suitable range of values of $p$, is recovered for
+a tamed Euler scheme which is used for approximating these solutions. To the
+best of the authors' knowledge, these are the first existence, uniqueness and
+approximation results for this class of SDEs.",2204.02343v1
+2022-04-12,Lattice paths and negatively indexed weight-dependent binomial coefficients,"In 1992, Loeb considered a natural extension of the binomial coefficients to
+negative entries and gave a combinatorial interpretation in terms of hybrid
+sets. He showed that many of the fundamental properties of binomial
+coefficients continue to hold in this extended setting. Recently, Formichella
+and Straub showed that these results can be extended to the $q$-binomial
+coefficients with arbitrary integer values and extended the work of Loeb
+further by examining arithmetic properties of the $q$-binomial coefficients. In
+this paper, we give an alternative combinatorial interpretation in terms of
+lattice paths and consider an extension of the more general weight-dependent
+binomial coefficients, first defined by the second author, to arbitrary integer
+values. Remarkably, many of the results of Loeb, Formichella and Straub
+continue to hold in the general weighted setting. We also examine important
+special cases of the weight-dependent binomial coefficients, including
+ordinary, $q$- and elliptic binomial coefficients as well as elementary and
+complete homogeneous symmetric functions.",2204.05505v2
+2022-05-13,Body Diagonal Diffusion Couple Method for Estimation of Tracer Diffusion Coefficients in a Multi-Principal Element Alloy,"The estimation of (n-1)2 interdiffusion coefficients in an n component system
+requires (n-1) diffusion paths to intersect or pass closely in the (n-1)
+dimensional space according to the body diagonal diffusion couple method. These
+interdiffusion coefficients are related to n(n-1) intrinsic (or n tracer
+diffusion coefficients), which cannot be estimated easily following the
+Kirkendall marker experiment in a multicomponent system despite their
+importance for understanding the atomic mechanism of diffusion and the
+physico-mechanical properties of materials. In this study, the estimation of
+tracer diffusion coefficients from only two diffusion profiles following the
+concept of the body diagonal diffusion couple method in a multicomponent system
+is demonstrated. Subsequently, one can estimate the intrinsic and
+interdiffusion coefficients. This reduces the overall effort up to a great
+extent since it needs only two instead of (n-1) diffusion profiles irrespective
+of the number of components, with an additional benefit of enabling the
+estimation of all types of diffusion coefficients. The available tracer
+diffusion coefficients estimated following the radiotracer method are compared
+to the data estimated in this study following this method. This method can also
+be extended to the systems in which the radiotracer method is not feasible.",2205.06550v1
+2022-06-15,A smile is all you need: Predicting limiting activity coefficients from SMILES with natural language processing,"Knowledge of mixtures' phase equilibria is crucial in nature and technical
+chemistry. Phase equilibria calculations of mixtures require activity
+coefficients. However, experimental data on activity coefficients is often
+limited due to high cost of experiments. For an accurate and efficient
+prediction of activity coefficients, machine learning approaches have been
+recently developed. However, current machine learning approaches still
+extrapolate poorly for activity coefficients of unknown molecules. In this
+work, we introduce the SMILES-to-Properties-Transformer (SPT), a natural
+language processing network to predict binary limiting activity coefficients
+from SMILES codes. To overcome the limitations of available experimental data,
+we initially train our network on a large dataset of synthetic data sampled
+from COSMO-RS (10 Million data points) and then fine-tune the model on
+experimental data (20 870 data points). This training strategy enables SPT to
+accurately predict limiting activity coefficients even for unknown molecules,
+cutting the mean prediction error in half compared to state-of-the-art models
+for activity coefficient predictions such as COSMO-RS, UNIFAC, and improving on
+recent machine learning approaches.",2206.07048v1
+2022-08-13,Coefficient problems for certain Close-to-Convex Functions,"In this paper, sharp bounds are established for the second Hankel determinant
+of logarithmic coefficients for normalised analytic functions satisfying
+certain differential inequality.",2208.06638v1
+2022-09-07,Social Media Engagement and Cryptocurrency Performance,"We study the problem of predicting the future performance of cryptocurrencies
+using social media data. We propose a new model to measure the engagement of
+users with topics discussed on social media based on interactions with social
+media posts. This model overcomes the limitations of previous volume and
+sentiment based approaches. We use this model to estimate engagement
+coefficients for 48 cryptocurrencies created between 2019 and 2021 using data
+from Twitter from the first month of the cryptocurrencies' existence. We find
+that the future returns of the cryptocurrencies are dependent on the engagement
+coefficients. Cryptocurrencies whose engagement coefficients are too low or too
+high have lower returns. Low engagement coefficients signal a lack of interest,
+while high engagement coefficients signal artificial activity which is likely
+from automated accounts known as bots. We measure the amount of bot posts for
+the cryptocurrencies and find that generally, cryptocurrencies with more bot
+posts have lower future returns. While future returns are dependent on both the
+bot activity and engagement coefficient, the dependence is strongest for the
+engagement coefficient, especially for short-term returns. We show that simple
+investment strategies which select cryptocurrencies with engagement
+coefficients exceeding a fixed threshold perform well for holding times of a
+few months.",2209.02911v1
+2022-10-21,Estimating and computing Kronecker Coefficients: a vector partition function approach,"We study the Kronecker coefficients $g_{\lambda, \mu, \nu}$ via a formula
+that was described by Mishna, Rosas, and Sundaram, in which the coefficients
+are expressed as a signed sum of vector partition function evaluations. In
+particular, we use this formula to determine formulas to evaluate, bound, and
+estimate $g_{\lambda, \mu, \nu}$ in terms of the lengths of the partitions
+$\lambda, \mu$, and $\nu$. We describe a computational tool to compute
+Kronecker coefficients $g_{\lambda, \mu, \nu}$ with $\ell(\mu) \leq 2,\
+\ell(\nu) \leq 4,\ \ell(\lambda) \leq 8$. We present a set of new vanishing
+conditions for the Kronecker coefficients by relating to the vanishing of the
+related atomic Kronecker coefficients, themselves given by a single vector
+partition function evaluation. We give a stable face of the Kronecker
+polyhedron for any positive integers $m,n$. Finally, we give upper bounds on
+both the atomic Kronecker coefficients and Kronecker coefficients.",2210.12128v1
+2023-02-27,Robust High-Dimensional Time-Varying Coefficient Estimation,"In this paper, we develop a novel high-dimensional coefficient estimation
+procedure based on high-frequency data. Unlike usual high-dimensional
+regression procedure such as LASSO, we additionally handle the heavy-tailedness
+of high-frequency observations as well as time variations of coefficient
+processes. Specifically, we employ Huber loss and truncation scheme to handle
+heavy-tailed observations, while $\ell_{1}$-regularization is adopted to
+overcome the curse of dimensionality. To account for the time-varying
+coefficient, we estimate local coefficients which are biased due to the
+$\ell_{1}$-regularization. Thus, when estimating integrated coefficients, we
+propose a debiasing scheme to enjoy the law of large number property and employ
+a thresholding scheme to further accommodate the sparsity of the coefficients.
+We call this Robust thrEsholding Debiased LASSO (RED-LASSO) estimator. We show
+that the RED-LASSO estimator can achieve a near-optimal convergence rate. In
+the empirical study, we apply the RED-LASSO procedure to the high-dimensional
+integrated coefficient estimation using high-frequency trading data.",2302.13658v2
+2023-03-15,On the differential operators of odd order with PT-symmetric periodic matrix coefficients,"In this paper we investigate the spectrum of the differential operators
+generated by the ordinary differential expression of odd order with
+PT-symmertic periodic matrix coefficients",2303.08703v1
+2023-03-30,Interior transmission problems with coefficients of low regularity,"We obtain parabolic transmission eigenvalue-free regions for both isotropic
+andanisotropic interior transmission problems with coefficients which are
+Lipschitznear the boundary",2303.17199v1
+2023-12-02,A Goldbach theorem for Laurent polynomials with positive integer coefficients,"We establish an analogue of the Goldbach conjecture for Laurent polynomials
+with positive integer coefficients.",2312.01189v1
+2024-02-08,Introducing q-deformed binomial coefficients of words,"Gaussian binomial coefficients are q-analogues of the binomial coefficients
+of integers. On the other hand, binomial coefficients have been extended to
+finite words, i.e., elements of the finitely generated free monoids. In this
+paper we bring together these two notions by introducing q-analogues of
+binomial coefficients of words. We study their basic properties, e.g., by
+extending classical formulas such as the q-Vandermonde and Manvel's et al.
+identities to our setting. As a consequence, we get information about the
+structure of the considered words: these q-deformations of binomial
+coefficients of words contain much richer information than the original
+coefficients. From an algebraic perspective, we introduce a q-shuffle and a
+family q-infiltration products for non-commutative formal power series.
+Finally, we apply our results to generalize a theorem of Eilenberg
+characterizing so-called p-group languages. We show that a language is of this
+type if and only if it is a Boolean combination of specific languages defined
+through q-binomial coefficients seen as polynomials over $\mathbb{F}_p$.",2402.05838v1
+2024-03-19,Reproducing the Acoustic Velocity Vectors in a Circular Listening Area,"Acoustic velocity vectors are important for human's localization of sound at
+low frequencies. This paper proposes a sound field reproduction algorithm,
+which matches the acoustic velocity vectors in a circular listening area. In
+previous work, acoustic velocity vectors are matched either at sweet spots or
+on the boundary of the listening area. Sweet spots restrict listener's
+movement, whereas measuring the acoustic velocity vectors on the boundary
+requires complicated measurement setup. This paper proposes the cylindrical
+harmonic coefficients of the acoustic velocity vectors in a circular area (CHV
+coefficients), which are calculated from the cylindrical harmonic coefficients
+of the global pressure (global CHP coefficients) by using the sound field
+translation formula. The global CHP coefficients can be measured by a circular
+microphone array, which can be bought off-the-shelf. By matching the CHV
+coefficients, the acoustic velocity vectors are reproduced throughout the
+listening area. Hence, listener's movements are allowed. Simulations show that
+at low frequency, where the acoustic velocity vectors are the dominant factor
+for localization, the proposed reproduction method based on the CHV
+coefficients results in higher accuracy in reproduced acoustic velocity vectors
+when compared with traditional method based on the global CHP coefficients.",2403.12630v1
+1994-05-16,Chaotic Scattering Theory of Transport and Reaction-Rate Coefficients,"The chaotic scattering theory is here extended to obtain escape-rate
+expressions for the transport coefficients appropriate for a simple classical
+fluid, or for a chemically reacting system. This theory allows various
+transport coefficients such as the coefficients of viscosity, thermal
+conductivity, etc., to be expressed in terms of the positive Lyapunov exponents
+and Kolmogorov-Sinai entropy of a set of phase space trajectories that take
+place on an appropriate fractal repeller. This work generalizes the previous
+results of Gaspard and Nicolis for the coefficient of diffusion of a particle
+moving in a fixed array of scatterers.",9405010v1
+1997-09-17,Transport Coefficients of InSb in a Strong Magnetic Field,"Improvement of a superconducting magnet system makes induction of a strong
+magnetic field easier. This fact gives us a possibility of energy conversion by
+the Nernst effect. As the first step to study the Nernst element, we measured
+the conductivity, the Hall coefficient, the thermoelectric power and the Nernst
+coefficient of the InSb, which is one of candidates of the Nernst elements.
+  From this experiment, it is concluded that the Nernst coefficient is smaller
+than the theoretical values. On the other hand, the conductivity, the Hall
+coefficient ant the thermoelectric power has the values expected by the theory.",9709188v1
+2003-08-11,Methods of calculation of a friction coefficient: Application to the nanotubes,"In this work we develop theoretical and numerical methods of calculation of a
+dynamic friction coefficient. The theoretical method is based on an adiabatic
+approximation which allows us to express the dynamic friction coefficient in
+terms of the time integral of the autocorrelation function of the force between
+both sliding objects. The motion of the objects and the autocorrelation
+function can be numerically calculated by molecular-dynamics simulations. We
+have successfully applied these methods to the evaluation of the dynamic
+friction coefficient of the relative motion of two concentric carbon nanotubes.
+The dynamic friction coefficient is shown to increase with the temperature.",0308206v2
+2005-03-21,Ninth and Tenth Order Virial Coefficients for Hard Spheres in D Dimensions,"We evaluate the virial coefficients B_k for k<=10 for hard spheres in
+dimensions D=2,...,8. Virial coefficients with k even are found to be negative
+when D>=5. This provides strong evidence that the leading singularity for the
+virial series lies away from the positive real axis when D>=5. Further analysis
+provides evidence that negative virial coefficients will be seen for some k>10
+for D=4, and there is a distinct possibility that negative virial coefficients
+will also eventually occur for D=3.",0503525v1
+2005-10-18,Demonstration of electron filtering to increase the Seebeck coefficient in ErAs:InGaAs/InGaAlAs superlattices,"In this letter, we explore electron filtering as a technique to increase
+Seebeck coefficient and the thermoelectric power factor of heterostructured
+materials over that of the bulk. We present a theoretical model in which
+Seebeck coefficient and the power factor can be increased in an InGaAs based
+composite material. Experimental measurements of the cross-plane Seebeck
+coefficient are presented and confirm the importance of the electron filtering
+technique to decouple the electrical conductivity and Seebeck coefficient to
+increase the thermoelectric power factor.",0510490v1
+2003-10-01,One-loop calculation of mass dependent ${\cal O}(a)$ improvement coefficients for the relativistic heavy quarks on the lattice,"We carry out the one-loop calculation of mass dependent ${\cal O}(a)$
+improvement coefficients in the relativistic heavy quark action recently
+proposed, employing the ordinary perturbation theory with the fictitious gluon
+mass as an infrared regulator. We also determine renormalization factors and
+improvement coefficients for the axial-vector current at the one-loop level. It
+is shown that the improvement coefficients are infrared finite at the one-loop
+level if and only if the improvement coefficients in the action are properly
+tuned at the tree level.",0310001v2
+2006-03-31,Dissipation coefficients for supersymmetric inflatonary models,"Dissipative effects can lead to a friction term in the equation of motion for
+an inflaton field during the inflationary era. The friction term may be linear
+and localised, in which case it is described by a dissipation coefficient. The
+dissipation coefficient is calculated here in a supersymmetric model with a two
+stage decay process in which the inflaton decays into a thermal gas of light
+particles through a heavy intermediate. At low temperatures, the dissipation
+coefficient $\propto T^3$ in a thermal approximation. Results are also given
+for a non-equilibrium anzatz. The dissipation coefficient is consistent with a
+warm inflationary regime for moderate ($\sim 0.1$) values of the coupling
+constants.",0603266v1
+2001-03-06,Multiple reflection expansion and heat kernel coefficients,"We propose the multiple reflection expansion as a tool for the calculation of
+heat kernel coefficients. As an example, we give the coefficients for a sphere
+as a finite sum over reflections, obtaining as a byproduct a relation between
+the coefficients for Dirichlet and Neumann boundary conditions. Further, we
+calculate the heat kernel coefficients for the most general matching conditions
+on the surface of a sphere, including those cases corresponding to the presence
+of delta and delta prime background potentials. In the latter case, the
+multiple reflection expansion is shown to be non-convergent.",0103037v2
+2004-12-02,Twistor Space Structure of the Box Coefficients of N=1 One-loop Amplitudes,"We examine the coefficients of the box functions in N=1 supersymmetric
+one-loop amplitudes. We present the box coefficients for all six point N=1
+amplitudes and certain all $n$ example coefficients. We find for ``next-to
+MHV'' amplitudes that these box coefficients have coplanar support in twistor
+space.",0412023v2
+2001-12-04,Periodicity properties of coefficients of half integral weight modular forms,"In this paper we prove a theorem about the coefficients in a block of a half
+integral weight modular form. We show that the result of Serre and Stark for
+weight 1/2 forms does not generalize to higher higher weights.
+  Let f be a half integral weight cusp form of weight at leat 3/2. We consider
+blocks of coefficients of f and prove that, under some weak assumptions on f,
+if such a coefficient block is periodic when considered as a function of in the
+square root of its index, then it must vanish completely. The proof is analytic
+in nature and uses Shimura's lifting theorem together with estimates on the
+order of growth of Fourier coefficients of modular forms.",0112320v1
+2004-03-09,An arithmetic formula for certain coefficients of the Euler product of Hecke polynomials,"In 1997 the author found a criterion for the Riemann hypothesis for the
+Riemann zeta function, involving the nonnegativity of certain coefficients
+associated with the Riemann zeta function. In 1999 Bombieri and Lagarias
+obtained an arithmetic formula for these coefficients using the ``explicit
+formula'' of prime number theory. In this paper, the author obtains an
+arithmetic formula for corresponding coefficients associated with the Euler
+product of Hecke polynomials, which is essentially a product of L-functions
+attached to weight 2 cusp forms (both newforms and oldforms) over Hecke
+congruence subgroups. The nonnegativity of these coefficients gives a criterion
+for the Riemann hypothesis for all these L-functions at once.",0403148v2
+2004-07-02,"A probabilistic approach to $q$-polynomial coefficients, Euler and Stirling numbers","It is known that Bernoulli scheme of independent trials with two outcomes is
+connected with the binomial coefficients. The aim of this paper is to indicate
+stochastic processes which are connected with the $q$-polynomial coefficients
+(in particular, with the $q$-binomial coefficients, or the Gaussian
+polynomials), Stirling numbers of the first and the second kind, and Euler
+numbers in a natural way. A probabilistic approach allows us to give very
+simple proofs of some identities for these coefficients.",0407029v1
+2004-09-27,Apparent Singularities of Linear Difference Equations with Polynomial Coefficients,"Let L be a linear difference operator with polynomial coefficients. We
+consider singularities of L that correspond to roots of the trailing (resp.
+leading) coefficient of L. We prove that one can effectively construct a left
+multiple with polynomial coefficients L' of L such that every singularity of L'
+is a singularity of L that is not apparent. As a consequence, if all
+singularities of L are apparent, then L has a left multiple whose trailing and
+leading coefficients equal 1.",0409508v1
+2005-10-27,Coefficients for the Farrell-Jones Conjecture,"We introduce the Farrell-Jones Conjecture with coefficients in an additive
+category with G-action. This is a variant of the Farrell-Jones Conjecture about
+the algebraic K- or L-Theory of a group ring RG. It allows to treat twisted
+group rings and crossed product rings. The conjecture with coefficients is
+stronger than the original conjecture but it has better inheritance properties.
+Since known proofs using controlled algebra carry over to the set-up with
+coefficients we obtain new results about the original Farrell-Jones Conjecture.
+The conjecture with coefficients implies the fibered version of the
+Farrell-Jones Conjecture.",0510602v1
+1993-09-22,Symmetry properties of SU3 vector coupling coefficients,"A presentation of the problem of calculating the vector coupling coefficients
+for $SU3 \supset SU2 \otimes U1$ is made, in the spirit of traditional
+treatments of SU2 coupling. The coefficients are defined as the overlap matrix
+element between product states and a coupled state with good SU3 quantum
+numbers. A technique for resolution of the outer degeneracy problem, based upon
+actions of the infinitesimal generators of SU3 is developed, which
+automatically produces vector coupling coefficients with symmetries under
+exchange of state labels which parallel the familiar symmetries of the SU2
+case. An algorithm for efficient computation of these coefficients is outlined,
+for which an ANSI C code is available.",9309023v1
+2003-12-16,Symmetry energy coefficients for asymmetric nuclear matter,"Symmetry energy coefficients of asymmetric nuclear matter are investigated as
+the inverse of nuclear matter polarizabilities with two different approaches.
+Firstly a general calculation shows they may depend on the neutron-proton
+asymmetry itself. The choice of particular prescriptions for the density
+fluctuations lead to certain isospin (n-p asymmetry) dependences of the
+polarizabilities. Secondly, with Skyrme type interactions, the static limit of
+the dynamical polarizability is investigated corresponding to the inverse
+symmetry energy coefficient which assumes different values at different
+asymmetries (and densities and temperatures). The symmetry energy coefficient
+(in the isovector channel) is found to increase as n-p asymmetries increase.
+The spin symmetry energy coefficient is also briefly investigated.",0312064v1
+2003-03-12,Accurate relativistic many-body calculations of van der Waals coefficients C_8 and C_10 for alkali-metal dimers,"We consider long-range interactions between two alkali-metal atoms in their
+respective ground states. We extend the previous relativistic many-body
+calculations of C_6 dispersion coefficients [Phys.Rev. Lett. {\bf 82}, 3589
+(1999)] to higher-multipole coefficients C_8 and C_10. A special attention is
+paid to usually omitted contribution of core-excited states. We calculate this
+contribution within relativistic random-phase approximation and demonstrate
+that for heavy atoms core excitations contribute as much as 10% to the
+dispersion coefficients. We tabulate results for both homonuclear and
+heteronuclear dimers and estimate theoretical uncertainties. The estimated
+uncertainties for C_8 coefficients range from 0.5% for Li_2 to 4% for Cs_2.",0303048v1
+2007-06-15,Materials with a desired refraction coefficient can be made by embedding small particles,"A method is proposed to create materials with a desired refraction
+coefficient, possibly negative one. The method consists of embedding into a
+given material small particles. Given $n_0(x)$, the refraction coefficient of
+the original material in a bounded domain $D \subset \R^3$, and a desired
+refraction coefficient $n(x)$, one calculates the number $N(x)$ of small
+particles, to be embedded in $D$ around a point $x \in D$ per unit volume of
+$D$, in order that the resulting new material has refraction coefficient
+$n(x)$.",0706.2322v1
+2007-10-10,On numerical averaging of the conductivity coefficient using two-scale extensions,"In this article we compare solutions to elliptic problems having rapidly
+oscillated conductivity (permeability, etc) coefficient with solutions to
+corresponding homogenized problems obtained from two-scale extensions of the
+initial coefficient. The comparison is done numerically on several one and two
+dimensional test problems with randomly generated coefficients for different
+intensities of oscillation. The dependency of the approximation error on the
+size of averaging is investigated.",0710.2072v1
+2008-02-11,Comments on combinatorial interpretation of fibonomial coefficients - an email style letter,"Up to our knowledge -since about 126 years we were lacking of classical type
+combinatorial interpretation of Fibonomial coefficients as it was Lukas
+\cite{1} - to our knowledge -who was the first who had defined Finonomial
+coefficients and derived a recurrence for them (see Historical Note in
+\cite{2,3}). Here we inform that a join combinatorial interpretation was found
+\cite{4} for all binomial-type coefficient - Fibonomial coefficients included.",0802.1381v1
+2008-06-18,Elliptic and parabolic second-order PDEs with growing coefficients,"We consider a second-order parabolic equation in $\bR^{d+1}$ with possibly
+unbounded lower order coefficients. All coefficients are assumed to be only
+measurable in the time variable and locally H\""older continuous in the space
+variables. We show that global Schauder estimates hold even in this case. The
+proof introduces a new localization procedure. Our results show that the
+constant appearing in the classical Schauder estimates is in fact independent
+of the $L_{\infty}$-norms of the lower order coefficients. We also give a proof
+of uniqueness which is of independent interest even in the case of bounded
+coefficients.",0806.3100v1
+2008-10-30,Neighboring ternary cyclotomic coefficients differ by at most one,"A cyclotomic polynomial Phi_n(x) is said to be ternary if n=pqr with p,q and
+r distinct odd prime factors. Ternary cyclotomic polynomials are the simplest
+ones for which the behaviour of the coefficients is not completely understood.
+Eli Leher showed in 2007 that neighboring ternary cyclotomic coefficients
+differ by at most four. We show that, in fact, they differ by at most one.
+Consequently, the set of coefficients occurring in a ternary cyclotomic
+polynomial consists of consecutive integers.
+  As an application we reprove in a simpler way a result of Bachman from 2004
+on ternary cyclotomic polynomials with an optimally large set of coefficients.",0810.5496v1
+2009-09-02,Creating materials with a desired refraction coefficient,"A method is given for creating material with a desired refraction
+coefficient. The method consists of embedding into a material with known
+refraction coefficient many small particles of size $a$. The number of
+particles per unit volume around any point is prescribed, the distance between
+neighboring particles is $O(a^{\frac{2-\kappa}{3}})$ as $a\to 0$, $0<\kappa<1$
+is a fixed parameter. The total number of the embedded particle is
+$O(a^{\kappa-2})$. The physical properties of the particles are described by
+the boundary impedance $\zeta_m$ of the $m-th$ particle,
+$\zeta_m=O(a^{-\kappa})$ as $a\to 0$. The refraction coefficient is the
+coefficient $n^2(x)$ in the wave equation $[\nabla^2+k^2n^2(x)]u=0$.",0909.0521v1
+2009-12-21,The K-level crossings of a random algebraic polynomial with dependent coefficients,"For a random polynomial with standard normal coefficients, two cases of the
+K-level crossings have been considered by Farahmand. When the coefficients are
+independent, Farahmand was able to derive an asymptotic value for the expected
+number of level crossings, even if K is allowed to grow to infinity.
+Alternatively, it was shown that when the coefficients have a constant
+covariance, the expected number of level crossings is reduced by half. In this
+paper we are interested in studying the behavior for dependent standard normal
+coefficients where the covariance is decaying and no longer constant. Using
+techniques similar to those of Farahmand, we will be able to show that for a
+wide range of covariance functions behavior similar to the independent case can
+be expected.",0912.4065v1
+2010-04-26,Motivic decompositions of projective homogeneous varieties and change of coefficients,"We prove that under some assumptions on an algebraic group $G$,
+indecomposable direct summands of the motive of a projective $G$-homogeneous
+variety with coefficients in $\mathbb{F}_p$ remain indecomposable if the ring
+of coefficients is any field of characteristic $p$. In particular for any
+projective $G$-homogeneous variety $X$, the decomposition of the motive of $X$
+in a direct sum of indecomposable motives with coefficients in any finite field
+of characteristic $p$ corresponds to the decomposition of the motive of $X$
+with coefficients in $\mathbb{F}_p$. We also construct a counterexample to this
+result in the case where $G$ is arbitrary.",1004.4417v2
+2010-08-30,Non-vanishing of Taylor coefficients and Poincaré series,"We prove recursive formulas for the Taylor coefficients of cusp forms, such
+as Ramanujan's Delta function, at points in the upper half-plane. This allows
+us to show the non-vanishing of all Taylor coefficients of Delta at CM points
+of small discriminant as well as the non-vanishing of certain Poincar\'e
+series. At a ""generic"" point all Taylor coefficients are shown to be non-zero.
+Some conjectures on the Taylor coefficients of Delta at CM points are stated.",1008.5092v3
+2011-04-18,Evidence of electron fractionalization in the Hall coefficient at Mott criticality,"Hall coefficient implies the mechanism for reconstruction of a Fermi surface,
+distinguishing competing scenarios for Mott criticality such as electron
+fractionalization, dynamical mean-field theory, and metal-insulator transition
+driven by symmetry breaking. We find that electron fractionalization leaves a
+signature for the Hall coefficient at Mott criticality in two dimensions, a
+unique feature differentiated from other theories. We evaluate the Hall
+coefficient based on the quantum Boltzman equation approach, guaranteeing gauge
+invariance in both longitudinal and transverse transport coefficients.",1104.3368v2
+2011-06-02,A new and efficient method for the computation of Legendre coefficients,"An efficient procedure for the computation of the coefficients of Legendre
+expansions is here presented. We prove that the Legendre coefficients
+associated with a function f(x) can be represented as the Fourier coefficients
+of an Abel-type transform of f(x). The computation of N Legendre coefficients
+can then be performed in O(N log N) operations with a single Fast Fourier
+Transform of the Abel-type transform of f(x).",1106.0463v1
+2011-06-23,The expansion in ultraspherical polynomials: a simple procedure for the fast computation of the ultraspherical coefficients,"We present a simple and fast algorithm for the computation of the
+coefficients of the expansion of a function f(cos u) in ultraspherical
+(Gegenbauer) polynomials. We prove that these coefficients coincide with the
+Fourier coefficients of an Abel-type transform of the function f(cos u). This
+allows us to fully exploit the computational efficiency of the Fast Fourier
+Transform, computing the first N ultraspherical coefficients in just O (N log_2
+N) operations.",1106.4718v2
+2011-10-27,OPE coefficient functions in terms of composite operators only. Singlet case,"A method for calculating coefficient functions of the operator product
+expansion, which was previously derived for the non-singlet case, is
+generalized for the singlet coefficient functions. The resulting formula
+defines coefficient functions entirely in terms of corresponding singlet
+composite operators without applying to elementary (quark and gluon) fields.
+Both ""diagonal"" and ""non-diagonal"" gluon coefficient functions in the product
+expansion of two electromagnetic currents are calculated in QCD. Their
+renormalization properties are studied.",1110.6059v2
+2012-01-17,Self-diffusion in granular gases: An impact of particles' roughness,"An impact of particles' roughness on the self-diffusion coefficient in
+granular gases is investigated. For a simplified collision model where the
+normal and tangential restitution coefficients are assumed to be constant we
+develop an analytical theory for the diffusion coefficient, which takes into
+account non-Maxwellain form of the velocity-angular velocity distribution
+function. We perform molecular dynamics simulations for a gas in a homogeneous
+cooling state and study the dependence of the self-diffusion coefficient on
+restitution coefficients. Our theoretical results are in a good agreement with
+the simulation data.",1201.3524v2
+2012-01-23,Constraints on the second order transport coefficients of an uncharged fluid,"In this note we have tried to determine how the existence of a local entropy
+current with non-negative divergence constrains the second order transport
+coefficients of an uncharged fluid, following the procedure described in
+\cite{Romatschke:2009kr}. Just on symmetry ground the stress tensor of an
+uncharged fluid can have 15 transport coefficients at second order in
+derivative expansion. The condition of entropy-increase gives five relations
+among these 15 coefficients. So finally the relativistic stress tensor of an
+uncharged fluid can have 10 independent transport coefficients at second order.",1201.4654v2
+2012-01-25,Fourier coefficients of three-dimensional vector-valued modular forms,"A thorough analysis is made of the Fourier coefficients for vector-valued
+modular forms associated to three-dimensional irreducible representations of
+the modular group. In particular, the following statement is verified for all
+but a finite number of equivalence classes: if a vector-valued modular form
+associated to such a representation has rational Fourier coefficients, then
+these coefficients have ""unbounded denominators"", i.e. there is a prime number
+p, depending on the representation, which occurs to an arbitrarily high power
+in the denominators of the coefficients. This provides a verification in the
+three-dimensional setting of a generalization of a long-standing conjecture
+about noncongruence modular forms.",1201.5165v2
+2012-06-26,Exact Recovery of Sparsely-Used Dictionaries,"We consider the problem of learning sparsely used dictionaries with an
+arbitrary square dictionary and a random, sparse coefficient matrix. We prove
+that $O (n \log n)$ samples are sufficient to uniquely determine the
+coefficient matrix. Based on this proof, we design a polynomial-time algorithm,
+called Exact Recovery of Sparsely-Used Dictionaries (ER-SpUD), and prove that
+it probably recovers the dictionary and coefficient matrix when the coefficient
+matrix is sufficiently sparse. Simulation results show that ER-SpUD reveals the
+true dictionary as well as the coefficients with probability higher than many
+state-of-the-art algorithms.",1206.5882v1
+2012-07-13,On extrapolation of virial coefficients of hard spheres,"Several methods of extrapolating the virial coefficients, including those
+proposed in this work, are discussed. The methods are demonstrated on
+predicting higher virial coefficients of one-component hard spheres. Estimated
+values of the eleventh to fifteenth virial coefficients are suggested. It has
+been speculated that the virial coefficients, B_n, beyond B_{14} may decrease
+with increasing n, and may reach negative values at large n. The extrapolation
+techniques may be utilized in other fields of science where the art of
+extrapolation plays a role.",1207.3259v1
+2012-10-06,Fermion observables for Lorentz violation,"The relationship between experimental observables for Lorentz violation in
+the fermion sector and the coefficients for Lorentz violation appearing in the
+lagrangian density is investigated in the minimal Standard-Model Extension. The
+definitions of the 44 fermion-sector observables, called the tilde
+coefficients, are shown to have a block structure. The c coefficients decouple
+from all the others, have six subspaces of dimension 1, and one of dimension 3.
+The remaining tilde coefficients form eight blocks, one of dimension 6, one of
+dimension 2, three of dimension 5, and three of dimension 4. By inverting these
+definitions, thirteen limits on the electron-sector tilde coefficients are
+deduced.",1210.2003v1
+2012-10-28,Dispersion for 1-d Scrodinger and wave equation with BV coefficients,"In this paper we analyze the dispersion for one dimensional wave and
+Schrodinger equations with BV coefficients. In the case of the wave equation we
+give a complete answer in terms of the variation of the logarithm of the
+coefficient showing that dispersion occurs if this variation is small enough
+but it may fail when the variation goes beyond a sharp threshold. For the
+Schrodigner equation we prove that the dispersion holds under the same
+smallness assumption on the variation of the coefficient. But, whether
+dispersion may fail for larger coefficients is unknown for the Schrodinger
+equation.",1210.7415v2
+2012-11-27,q-Catalan bases and their dual coefficients,"We define q-Catalan bases which are a generalization of the q-polynomials
+z^n(z,q)_n. The determination of their dual bases involves some q-power series
+termed dual coefficients. We show how these dual coefficients occur in the
+solution of some equations with q-commuting coefficients and solve an abstract
+q-Segner recursion. We study the connection between this theory and Garsia's
+(1981). The overall flavor of this work is to show how some properties of
+q-Catalan numbers are in fact instances of much more general results on dual
+coefficients.",1211.6206v1
+2013-07-10,Long range interaction coefficients for ytterbium dimers,"We evaluate the electric-dipole and electric-quadrupole static and dynamic
+polarizabilities for the 6s^2 ^1S_0, 6s6p ^3P_0, and 6s6p ^3P_1 states and
+estimate their uncertainties. A methodology is developed for an accurate
+evaluation of the van der Waals coefficients of dimers involving excited state
+atoms with strong decay channel to the ground state. This method is used for
+evaluation of the long range interaction coefficients of particular
+experimental interest, including the C_6 coefficients for the Yb-Yb
+^1S_0+^3P_{0,1} and ^3P_0+^3P_0 dimers and C_8 coefficients for the ^1S_0+^1S_0
+and ^1S_0+^3P_1 dimers.",1307.2656v1
+2013-07-23,Polynomials with integer coefficients and their zeros,"We study several related problems on polynomials with integer coefficients.
+This includes the integer Chebyshev problem, and the Schur problems on means of
+algebraic numbers. We also discuss interesting applications to approximation by
+polynomials with integer coefficients, and to the growth of coefficients for
+polynomials with roots located in prescribed sets. The distribution of zeros
+for polynomials with integer coefficients plays an important role in all of
+these problems.",1307.6200v1
+2013-08-13,How to Extend Karolyi and Nagy's BRILLIANT Proof of the Zeilberger-Bressoud q-Dyson Theorem in order to Evaluate ANY Coefficient of the q-Dyson Product,"We show how to extend the Karolyi-Nagy beautiful proof of the
+Zeilberger-Bressoud q-Dyson theorem, (first proved by Zeilberger and Bressoud
+in 1985, and originally conjectured by George Andrews in 1975), that states
+that the constant term of a certain Laurent polynomial equals the q-multinomial
+coefficient, how to evaluate any other specific coefficient. The algorithm
+implies that any such coefficient is always a certain rational function (that
+the algorithm finds) times the q-multinomial coefficient.",1308.2983v1
+2013-09-25,Matrix Fourier transform with discontinuous coefficients,"The explicit construction of direct and inverse Fourier's vector transform
+with discontinuous coefficients is presented. The technique of applying
+Fourier's vector transform with discontinuous coefficients for solving problems
+of mathematical physics.Multidimensional integral transformations with
+non-separated variables for problems with discontinuous coefficients are
+constructed in this work. The coefficient discontinuities focused on the of
+parallel hyperplanes. In this work explicit formulas for the kernels in the
+case of ideal coupling conditions are obtained; the basic identity of the
+integral transform is proved; technique of integral transforms is developed",1309.6566v1
+2013-11-25,A model for generating tunable clustering coefficients independent of the number of nodes in scale free and random networks,"Probabilistic networks display a wide range of high average clustering
+coefficients independent of the number of nodes in the network. In particular,
+the local clustering coefficient decreases with the degree of the subtending
+node in a complicated manner not explained by any current models. While a
+number of hypotheses have been proposed to explain some of these observed
+properties, there are no solvable models that explain them all. We propose a
+novel growth model for both random and scale free networks that is capable of
+predicting both tunable clustering coefficients independent of the network
+size, and the inverse relationship between the local clustering coefficient and
+node degree observed in most networks.",1311.6401v1
+2014-03-11,Elliptic and parabolic equations with measurable coefficients in weighted Sobolev spaces,"We consider both divergence and non-divergence parabolic equations on a half
+space in weighted Sobolev spaces. All the leading coefficients are assumed to
+be only measurable in the time and one spatial variable except one coefficient,
+which is assumed to be only measurable either in the time or the spatial
+variable. As functions of the other variables the coefficients have small
+bounded mean oscillation (BMO) semi-norms. The lower-order coefficients are
+allowed to blow up near the boundary with a certain optimal growth condition.
+As a corollary, we also obtain the corresponding results for elliptic
+equations.",1403.2459v1
+2014-06-11,Bounds on the Kronecker coefficients,"We present several upper and lower bounds on the Kronecker coefficients of
+the symmetric group. We prove $k$-stability of the Kronecker coefficients
+generalizing the (usual) stability, and giving a new upper bound. We prove a
+lower bound via the characters of $S_n$. We apply these and other results to
+generalize Sylvester's unimodality of the $q$-binomial coefficients
+$\binom{n}{k}_q$ as polynomials in $q$: we derive explicit sharp bounds on the
+differences of their consecutive coefficients.",1406.2988v2
+2014-06-13,A product formula for certain Littlewood-Richardson coefficients for Jack and Macdonald polynomials,"Jack polynomials generalize several classical families of symmetric
+polynomials, including Schur polynomials, and are further generalized by
+Macdonald polynomials. In 1989, Richard Stanley conjectured that if the
+Littlewood-Richardson coefficient for a triple of Schur polynomials is 1, then
+the corresponding coefficient for Jack polynomials can be expressed as a
+product of weighted hooks of the Young diagrams associated to the partitions
+indexing the coefficient. We prove a special case of this conjecture in which
+the partitions indexing the Littlewood-Richardson coefficient have at most 3
+parts. We also show that this result extends to Macdonald polynomials.",1406.3391v1
+2014-10-20,An overpartition analogue of the $q$-binomial coefficients,"We define an overpartition analogue of Gaussian polynomials (also known as
+$q$-binomial coefficients) as a generating function for the number of
+overpartitions fitting inside the $M \times N$ rectangle. We call these new
+polynomials over Gaussian polynomials or over $q$-binomial coefficients. We
+investigate basic properties and applications of over $q$-binomial
+coefficients. In particular, via the recurrences and combinatorial
+interpretations of over q-binomial coefficients, we prove a Rogers-Ramaujan
+type partition theorem.",1410.5301v2
+2015-03-18,Re-visiting the Distance Coefficient in Gravity Model,"This paper revisits the classic gravity model in international trade and
+reexamines the distance coefficient. As pointed out by Frankel (1997), this
+coefficient measures the relative unit transportation cost between short
+distance and long distance rather than the absolute level of average
+transportation cost. Our results confirm this point in the sense that the
+coefficient has been very stable between 1991-2006, despite the obvious
+technological progress taken place during this period. Moreover, by comparing
+the sensitivity of these coefficients to change in oil prices at short periods
+of time, in which technology remained unchanged, we conclude that the average
+technology has indeed reduced the average trading cost. The results are robust
+when we divide the aggregate international trades into different industries.",1503.05283v2
+2015-06-09,Combinatorics on a family of reduced Kronecker coefficients,"The reduced Kronecker coefficients are particular instances of Kronecker
+coefficients that contain enough information to recover them. In this notes we
+compute the generating function of a family of reduced Kronecker coefficients.
+We also gives its connection to the plane partitions, which allows us to check
+that this family satisfies the saturation conjecture for reduced Kronecker
+coefficients, and that they are weakly increasing. Thanks to its generating
+function we can describe our family by a quasipolynomial, specifying its degree
+and period.",1506.02829v1
+2015-12-28,Non-vanishing and sign changes of Hecke eigenvalues for half-integral weight cusp forms,"In this paper, we consider three problems about signs of the Fourier
+coefficients of a cusp form $\mathfrak{f}$ with half-integral
+weight:\begin{itemize}\item[--]The first negative coefficient of the sequence
+$\{\mathfrak{a}\_{\mathfrak{f}}(tn^2)\}\_{n\in \N}$,\item[--]The number of
+coefficients $\mathfrak{a}\_{\mathfrak{f}}(tn^2)$ of same
+signs,\item[--]Non-vanishing of coefficients
+$\mathfrak{a}\_{\mathfrak{f}}(tn^2)$ in short intervals and in arithmetic
+progressions,\end{itemize}where $\mathfrak{a}\_{\mathfrak{f}}(n)$ is the $n$-th
+Fourier coefficient of $\mathfrak{f}$ and $t$ is a square-free integersuch that
+$\mathfrak{a}\_{\mathfrak{f}}(t)\not=0$.",1512.08400v1
+2015-12-29,Some local questions for hyperbolic systems with non-regular time dependent coefficients,"In this note we investigate local properties for microlocally symmetrizable
+hyperbolic systems with just time dependent coefficients. Thanks to
+Paley-Wiener theorem, we establish finite propagation speed by showing precise
+estimates on the evolution of the support of the solution in terms of suitable
+norms of the coefficients of the operator and of the symmetrizer. From this
+result, local existence and uniqueness follow by quite standard methods. Our
+argument relies on the use of Fourier transform, and it cannot be extended to
+operators whose coefficients depend also on the space variables. On the other
+hand, it works under very mild regularity assumptions on the coefficients of
+the operator and of the symmetrizer.",1512.08745v1
+2016-01-18,Do thermal diffusion and Dufour coefficients satisfy Onsager's reciprocity relation?,"It is commonly admitted that in liquids the thermal diffusion and Dufour
+coefficients $D_{T}$\ and $D_{F}$ satisfy Onsager's reciprocity. From their
+relation to the cross-coefficients of the phenomenological equations, we are
+led to the conclusion that this is not the case in general. As illustrative and
+physically relevant examples, we discuss micellar solutions and colloidal
+suspensions, where $D_{T}$ arises from chemical reactions or viscous effects
+but is not related to the Dufour coefficient $D_{F}$. The situation is less
+clear for binary molecular mixtures; available experimental and simulation data
+do not settle the question whether $D_{T}$\ and $D_{F}$ are reciprocal
+coefficients.",1601.04435v1
+2016-05-31,Small Values of Coefficients of a Half Lerch Sum,"Andrews, Dyson and Hickerson proved many interesting properties of
+coefficients for a Ramanujan's $q$-hypergeometric series by relating it to real
+quadratic field $\Q(\sqrt{6})$ and using the arithmetic of $\Q(\sqrt{6})$,
+hence solved a conjecture of Andrews on the distributions of its Fourier
+coefficients. Motivated by Andrews's conjecture, we discuss an interesting
+$q$-hypergeometric series which comes from a Lerch sum and rank and crank
+moments for partitions and overpartitions. We give Andrews-like conjectures for
+its coefficients. We obtain partial results on the distributions of small
+values of its coefficients toward these conjectures.",1605.09508v2
+2016-12-16,A correlation coefficient of belief functions,"How to manage conflict is still an open issue in Dempster-Shafer evidence
+theory. The correlation coefficient can be used to measure the similarity of
+evidence in Dempster-Shafer evidence theory. However, existing correlation
+coefficients of belief functions have some shortcomings. In this paper, a new
+correlation coefficient is proposed with many desirable properties. One of its
+applications is to measure the conflict degree among belief functions. Some
+numerical examples and comparisons demonstrate the effectiveness of the
+correlation coefficient.",1612.05497v2
+2017-04-30,Use of difference tables at studying of properties of binomial coefficients,"Some properties of diagonal binomial coefficients were studied in respect to
+frequency of their units digits. An approach was formulated that led to use of
+difference tables to predict if certain units digits can appear in the values
+of binomial coefficients at quadratic terms of the binomial theorem. Frequency
+distributions of units digits of binomial coefficients contain gaps (zero
+frequency) under most common numbering systems with supposed exclusion to
+systems with 2^n bases. Binomial coefficient arithmetics may be used to model
+cell population dynamics in a multicellular organism, which implies that the
+dynamics obeys power function laws.",1705.00272v1
+2017-05-29,Several extreme coefficients of the Tutte polynomial of graphs,"Let $t_{i,j}$ be the coefficient of $x^iy^j$ in the Tutte polynomial
+$T(G;x,y)$ of a connected bridgeless and loopless graph $G$ with order $n$ and
+size $m$. It is trivial that $t_{0,m-n+1}=1$ and $t_{n-1,0}=1$. In this paper,
+we obtain expressions of another eight extreme coefficients $t_{i,j}$'s with
+$(i,j)=(0,m-n)$,$(0,m-n-1)$,$(n-2,0)$,$(n-3,0)$,$(1,m-n)$,$(1,m-n-1)$,$(n-2,1)$
+and $(n-3,1)$ in terms of small substructures of $G$. Among them, the former
+four can be obtained by using coefficients of the highest, second highest and
+third highest terms of chromatic or flow polynomials, and vice versa. We also
+discuss their duality property and their specializations to extreme
+coefficients of the Jones polynomial.",1705.10023v1
+2017-06-11,"The peculiar (monic) polynomials, the zeros of which equal their coefficients","We evaluate the number of monic polynomials (of arbitrary degree $N$) the
+zeros of which equal their coefficients when these are allowed to take
+arbitrary complex values. In the following, we call polynomials with this
+property {\em peculiar\/} polynomials. We further show that the problem of
+determining the peculiar polynomials of degree $N$ simplifies when any of the
+coefficients is either 0 or 1. We proceed to estimate the numbers of peculiar
+polynomials of degree $N$ having one coefficient zero, or one coefficient equal
+to one, or neither.",1706.03405v1
+2018-02-08,Gaussian binomial coefficients with negative arguments,"Loeb showed that a natural extension of the usual binomial coefficient to
+negative (integer) entries continues to satisfy many of the fundamental
+properties. In particular, he gave a uniform binomial theorem as well as a
+combinatorial interpretation in terms of choosing subsets of sets with a
+negative number of elements. We show that all of this can be extended to the
+case of Gaussian binomial coefficients. Moreover, we demonstrate that several
+of the well-known arithmetic properties of binomial coefficients also hold in
+the case of negative entries. In particular, we show that Lucas' Theorem on
+binomial coefficients modulo $p$ not only extends naturally to the case of
+negative entries, but even to the Gaussian case.",1802.02684v1
+2018-02-15,Comparing Hecke Coefficients of Automorphic Representations,"We prove a number of unconditional statistical results of the Hecke
+coefficients for unitary cuspidal representations of $\operatorname{GL}(2)$
+over number fields. Using partial bounds on the size of the Hecke coefficients,
+instances of Langlands functoriality, and properties of Rankin-Selberg
+$L$-functions, we obtain bounds on the set of places where linear combinations
+of Hecke coefficients are negative. Under a mild functoriality assumption we
+extend these methods to $\operatorname{GL}(n)$. As an application, we obtain a
+result related to a question of Serre about the occurrence of large Hecke
+eigenvalues of Maass forms. Furthermore, in the cases where the Ramanujan
+conjecture is satisfied, we obtain distributional results of the Hecke
+coefficients at places varying in certain congruence or Galois classes.",1802.05684v2
+2018-06-29,Asymptotics of recurrence coefficients for the Laguerre weight with a singularity at the edge,"In this paper, We study the asymptotics of the leading coefficients and the
+recurrence coefficients for the orthogonal polynomials with repect to the
+Laguerre weight with singularity of root type and jump type at the soft edge
+via the Deift-Zhou steepest descent method. The asymptotic formulas of the
+leading coefficients and the recurrence coefficients for large n are described
+in terms of a class of analytic solutions to the the {\sigma}-form of the
+Painlev\'e II equation and the Painlev\'e XXXIV equation.",1807.00088v3
+2018-07-14,Estimating transport coefficients of interacting pion gas with K-matrix cross sections,"We estimate the transport coefficients, $viz.$, shear and bulk viscosities as
+well as thermal and electrical conductivities, of hot pionic matter using
+relativistic Boltzmann equation in relaxation time approximation. We use
+K-matrix parametrization of pion-pion cross sections to estimate the transport
+coefficients which incorporate multiple heavy resonances while simultaneously
+preserving the unitarity of S-matrix. We compare transport coefficients
+estimated using K-matrix parametrization with existing literature on pionic
+transport coefficients. We find that the K-matrix scheme estimations are in
+reasonable agreement with previous results.",1807.05370v2
+2018-11-01,Wellposedness of the two-sided variable coefficient Caputo flux fractional diffusion equation and error estimate of its spectral approximation,"In this article a two-sided variable coefficient fractional diffusion
+equation (FDE) is investigated, where the variable coefficient occurs outside
+of the fractional integral operator. Under a suitable transformation the
+variable coefficient equation is transformed to a constant coefficient
+equation. Then, using the spectral decomposition approach with Jacobi
+polynomials, we proved the wellposedness of the model and the regularity of its
+solution. A spectral approximation scheme is proposed and the accuracy of its
+approximation studied. Two numerical experiments are presented to demonstrate
+the derived error estimates.",1811.00582v1
+2018-11-13,Equilibrium Formulae for Transverse Magneto-transport of Strongly Correlated Metals,"Exact formulas for the Hall coefficient, modified Nernst coefficient, and
+thermal Hall coefficient of metals are derived from the Kubo formula. These
+coefficients depend exclusively on equilibrium (time independent)
+susceptibilities, which are significantly easier to compute than
+conductivities. For weak isotropic scattering, Boltzmann theory is recovered.
+For strong scattering, well controlled methods for thermodynamic functions are
+available. As an example, the Hall sign reversals of lattice bosons near the
+Mott insulator phases are determined. Appendices include mathematical
+supplements and instructions for calculating the coefficients.",1811.05775v3
+2019-01-14,Variable coefficient complex Ginzburg-Landau equation,"The complex Ginzburg-Landau equation (CGLE) is a general model of spatially
+extended nonequilibrium systems. In this paper, an analytical method for a
+variable coefficient CGLE is presented to obtain exact solutions. Variable
+transformations for space and time variables with coefficient functions yield
+an imaginary time advection equation related to a complex valued characteristic
+curve. The variable coefficient CGLE is transformed into the nonlinear
+Schr{""\o}dinger equation (NLSE) on the complex valued characteristic curve.
+This result indicates that the analytical solutions of the NLSE generate that
+of the variable coefficient CGLE.",1901.04205v1
+2019-02-12,Some properties of coefficients of cyclotomic polynomials,"This paper investigates coefficients of cyclotomic polynomials theoretically
+and experimentally. We prove the following result. {{\em If $n=p_1\ldots p_k$
+where $p_i$ are odd primes and
+  $p_1<p_2<\ldots<p_r<p_1+p_2<p_{r+1}<\ldots<p_t$ with $t\geq 3$ odd,
+  then the numbers $-(r-2),-(r-3),\ldots, r-2, r-1$ are all coefficients
+  of the cyclotomic polynomial $\Phi_{2n}$. Furthermore, if $1+p_r<p_1+p_2$
+then $1-r$ is also a coefficient of $\Phi_{2n}$.} In the experimental part, in
+two instances we present computational evidence for asymptotic symmetry between
+distribution of positive and negative coefficients, and state the resulting
+conjectures.}",1902.04631v1
+2019-03-15,On the $\mathrm{L}^p$-theory for second-order elliptic operators in divergence form with complex coefficients,"Given a complex, elliptic coefficient function we investigate for which
+values of $p$ the corresponding second-order divergence form operator,
+complemented with Dirichlet, Neumann or mixed boundary conditions, generates a
+strongly continuous semigroup on $\mathrm{L}^p(\Omega)$. Additional properties
+like analyticity of the semigroup, $\mathrm{H}^\infty$-calculus and maximal
+regularity are also discussed. Finally we prove a perturbation result for real
+coefficients that gives the whole range of $p$'s for small imaginary parts of
+the coefficients. Our results are based on the recent notion of
+$p$-ellipticity, reverse H\""older inequalities and Gaussian estimates for the
+real coefficients.",1903.06692v1
+2019-04-01,Tree Boosted Varying Coefficient Models,"This paper investigates the integration of gradient boosted decision trees
+and varying coefficient models. We introduce the tree boosted varying
+coefficient framework which justifies the implementation of decision tree
+boosting as the nonparametric effect modifiers in varying coefficient models.
+This framework requires no structural assumptions in the space containing the
+varying coefficient covariates, is easy to implement, and keeps a balance
+between model complexity and interpretability. To provide statistical
+guarantees, we prove the asymptotic consistency of the proposed method under
+the regression settings with $L^2$ loss. We further conduct a thorough
+empirical study to show that the proposed method is capable of providing
+accurate predictions as well as intelligible visual explanations.",1904.01058v1
+2019-04-13,Virial coefficients expressed by heat kernel coefficients,"In this paper, we generally expressed the virial expansion of ideal quantum
+gases by the heat kernel coefficients for the corresponding Laplace type
+operator. As examples, we give the virial coefficients for quantum gases in
+$d$-dimensional confined space and spheres, respectively. Our results show
+that, the relative correction from the boundary to the second virial
+coefficient is independent of the dimension and it always enhances the quantum
+exchange interaction. In $d$-dimensional spheres, however, the influence of the
+curvature enhances the quantum exchange interaction in two dimensions, but
+weakens it in higher dimensions ($d>3$).",1904.06496v1
+2019-05-23,Shear Thickening of Dense Suspensions: The Role of Friction,"Shear thickening of particle suspensions is characterized by a transition
+between lubricated and frictional contacts between the particles. Using 3D
+numerical simulations, we study how the inter-particle friction coefficient
+influences the effective macroscopic friction coefficient and hence the
+microstructure and rheology of dense shear thickening suspensions. We propose
+expressions for effective friction coefficient in terms of distance to jamming
+for varying shear stresses and particle friction coefficient values. We find
+effective friction coefficient to be rather insensitive to interparticle
+friction, which is perhaps surprising but agrees with recent theory and
+experiments.",1905.09732v1
+2019-08-01,Measuring the Clustering Strength of a Network via the Normalized Clustering Coefficient,"In this paper, we propose a novel statistic of networks, the normalized
+clustering coefficient, which is a modified version of the clustering
+coefficient that is robust to network size, network density and degree
+heterogeneity under different network generative models. In particular, under
+the degree corrected block model (DCBM), the ""in-out-ratio"" could be inferred
+from the normalized clustering coefficient. Asymptotic properties of the
+proposed indicator are studied under three popular network generative models.
+The normalized clustering coefficient can also be used for networks clustering,
+network sampling as well as dynamic network analysis. Simulations and real data
+analysis are carried out to demonstrate these applications.",1908.00523v1
+2019-08-18,A New Approach to Determine the Coefficient of Skewness and An Alternative Form of Boxplot,"To solve the problems in measuring coefficient of skewness related to extreme
+value, irregular distance from the middle point and distance between two
+consecutive numbers, ""Rank skewness"" a new measure of the coefficient of
+skewness has been proposed in this paper. Comparing with other measures of the
+coefficient of skewness, proposed measure of the coefficient of skewness
+performs better specially for skewed distribution. An alternative of five point
+summary boxplot, a four point summary graph has also been proposed which is
+simpler than the traditional boxplot. It is based on all observation and give
+better result than the five point summary.",1908.06400v1
+2019-12-10,Variable-coefficient symbolic computation approach for finding multiple rogue wave solutions of nonlinear system with variable coefficients,"In this paper, a variable-coefficient symbolic computation approach is
+proposed to solve the multiple rogue wave solutions of nonlinear equation with
+variable coefficients. As an application, a (2+1)-dimensional
+variable-coefficient Kadomtsev-Petviashvili equation is investigated. The
+multiple rogue wave solutions are obtained and their dynamics features are
+shown in some 3D and contour plots.",1912.04270v1
+2020-01-21,Strong solutions of forward-backward stochastic differential equations with measurable coefficients,"This paper investigates solvability of fully coupled systems of
+forward-backward stochastic differential equations (FBSDEs) with irregular
+coefficients. In particular, we assume that the coefficients of the FBSDEs are
+merely measurable and bounded in the forward process. We crucially use
+compactness results from the theory of Malliavin calculus to construct strong
+solutions. Despite the irregularity of the coefficients, the solutions turn out
+to be differentiable, at least in the Malliavin sense and, as functions of the
+initial variable, in the Sobolev sense.",2001.07753v2
+2020-01-31,"On Fourier coefficients of elliptic modular forms $\bmod \, \ell$ with applications to Siegel modular forms","We study several aspects of nonvanishing Fourier coefficients of elliptic
+modular forms $\bmod \ell$, partially answering a question of
+Bella\""iche-Soundararajan concerning the asymptotic formula for the count of
+the number of Fourier coefficients upto $x$ which do not vanish $\bmod \ell$.
+We also propose a precise conjecture as a possible answer to this question.
+Further, we prove several results related to the nonvanishing of arithmetically
+interesting (e.g., primitive or fundamental) Fourier coefficients $\bmod \ell $
+of a Siegel modular form with integral algebraic Fourier coefficients provided
+$\ell$ is large enough. We also make some efforts to make this ""largeness"" of
+$\ell$ effective.",2001.11700v1
+2020-04-06,Best constant for Ulam stability of first-order h-difference equations with periodic coefficient,"We establish the best (minimum) constant for Ulam stability of first-order
+linear $h$-difference equations with a periodic coefficient. First, we show
+Ulam stability and find the Ulam stability constant for a first-order linear
+equation with a period-two coefficient, and give several examples. In the last
+section we prove Ulam stability for a periodic coefficient function of
+arbitrary finite period. Results on the associated first-order perturbed linear
+equation with periodic coefficient are also included.",2004.03465v1
+2020-04-20,On the wave equation with multiplicities and space-dependent irregular coefficients,"In this paper we study the well-posedness of the Cauchy problem for a wave
+equation with multiplicities and space-dependent irregular coefficients. As in
+\cite{GR:14} in order to give a meaningful notion of solution, we employ the
+notion of very weak solution, which construction is based on a parameter
+dependent regularisation of the coefficients via mollifiers. We prove that,
+even with distributional coefficients, a very weak solution exists for our
+Cauchy problem and it converges to the classical one when the coefficients are
+smooth. The dependence on the mollifiers of very weak solutions is investigated
+at the end of the paper in some instructive examples.",2004.09657v1
+2020-05-16,Numerical solution of linear differential equations with discontinuous coefficients and Henstock integral,"In this article we consider the problem of approximative solution of linear
+differential equations $y'+p(x)y=q(x)$ with discontinuous coefficients $p$ and
+$q$. We assume that coefficients of such equation are Henstock integrable
+functions. To find the approximative solution we change the original Cauchy
+problem to another problem with piecewise-constant coefficients. The sharp
+solution of this new problems is the approximative solution of the original
+Cauchy problem. We find the degree approximation in terms of modulus of
+continuity $\omega_\delta (P),\ \omega_\delta (Q)$, where $P$ and $Q$ are
+$f$-primitive for coefficients $p$ and $q$.",2005.07978v1
+2020-05-21,The Lanczos Approximation for the $Γ$-Function with Complex Coefficients,"We examined the properties of the coefficients of the \cite{lanczos1964}
+approximation of the $\Gamma$-function with complex values of the free
+parameter together with the convergence properties of the approximation when
+using these coefficients. We report that for fixed real parts of the free
+parameter that using complex coefficients both increases the computational cost
+of the Lanczos approximation while drecreasing the accuracy. We conclude that
+in practical applications of numerical evaluation of the $\Gamma$-function only
+coefficients generated with real values of the free parameter should be used.",2005.10449v1
+2020-06-07,Improved Recursive Computation of Clebsch-Gordan Coefficients,"Fast, accurate, and stable computation of the Clebsch-Gordan (C-G)
+coefficients is always desirable, for example, in light scattering simulations,
+the translation of the multipole fields, quantum physics and chemistry. Current
+recursive methods for computing the C-G coefficients are often unstable for
+large quantum numbers due to numerical overflow or underflow. In this paper, we
+present an improved method, the so-called sign-exponent recurrence, for the
+recursive computation of C-G coefficients. The result shows that the proposed
+method can significantly improve the stability of the computation without
+losing its efficiency, producing accurate values for the C-G coefficients even
+with very large quantum numbers.",2006.04267v2
+2020-09-16,Parabolic and elliptic equations with singular or degenerate coefficients: the Dirichlet problem,"We consider the Dirichlet problem for a class of elliptic and parabolic
+equations in the upper-half space $\mathbb{R}^d_+$, where the coefficients are
+the product of $x_d^\alpha, \alpha \in (-\infty, 1),$ and a bounded uniformly
+elliptic matrix of coefficients. Thus, the coefficients are singular or
+degenerate near the boundary $\{x_d =0\}$ and they may not locally integrable.
+The novelty of the work is that we find proper weights under which the
+existence, uniqueness, and regularity of solutions in Sobolev spaces are
+established. These results appear to be the first of their kind and are new
+even if the coefficients are constant. They are also readily extended to
+systems of equations.",2009.07967v1
+2020-09-28,Homological Filling Functions with Coefficients,"How hard is it to fill a loop in a Cayley graph with an unoriented surface?
+Following a comment of Gromov in ""Asymptotic invariants of infinite groups"", we
+define homological filling functions of groups with coefficients in a group
+$R$. Our main theorem is that the coefficients make a difference. That is, for
+every $n \geq 1$ and every pair of coefficient groups $A, B \in
+\{\mathbb{Z},\mathbb{Q}\} \cup \{\mathbb{Z}/p\mathbb{Z} : p\text{ prime}\}$,
+there is a group whose filling functions for $n$-cycles with coefficients in
+$A$ and $B$ have different asymptotic behavior.",2009.13489v3
+2020-10-05,Transversal flexoelectric coefficient for nanostructures at finite deformations from first principles,"We present a novel formulation for calculating the transversal flexoelectric
+coefficient of nanostructures at finite deformations from first principles.
+Specifically, we introduce the concept of \emph{radial polarization} to make
+the coefficient a well-defined quantity for uniform bending deformations. We
+use the framework to calculate the flexoelectric coefficient for group IV
+atomic monolayers using density functional theory. We find that graphene's
+coefficient is significantly larger than previously reported, with a charge
+transfer mechanism that differs from other members of its group.",2010.01747v1
+2020-12-09,The Relationship between Maximum Principle and Dynamic Programming Principle for Stochastic Recursive Control Problem with Random Coefficients,"This paper aims to explore the relationship between maximum principle and
+dynamic programming principle for stochastic recursive control problem with
+random coefficients. Under certain regular conditions for the coefficients, the
+relationship between the Hamilton system with random coefficients and
+stochastic Hamilton-Jacobi-Bellman equation is obtained. It is very different
+from the deterministic coefficients case since stochastic
+Hamilton-Jacobi-Bellman equation is a backward stochastic partial differential
+equation with solution being a pair of random fields rather than a
+deterministic function. A linear quadratic recursive utility optimization
+problem is given as an explicitly illustrated example based on this kind of
+relationship.",2012.04814v1
+2021-01-19,Improved Coefficients for the Karagiannidis-Lioumpas Approximations and Bounds to the Gaussian Q-Function,"We revisit the Karagiannidis-Lioumpas (KL) approximation of the Q-function by
+optimizing its coefficients in terms of absolute error, relative error and
+total error. For minimizing the maximum absolute/relative error, we describe
+the targeted uniform error functions by sets of nonlinear equations so that the
+optimized coefficients are the solutions thereof. The total error is minimized
+with numerical search. We also introduce an extra coefficient in the KL
+approximation to achieve significantly tighter absolute and total error at the
+expense of unbounded relative error. Furthermore, we extend the KL expression
+to lower and upper bounds with optimized coefficients that minimize the error
+measures in the same way as for the approximations.",2101.07631v1
+2021-06-09,Relative Clustering Coefficient,"In this paper, we relatively extend the definition of global clustering
+coefficient to another clustering, which we call it relative clustering
+coefficient. The idea of this definition is to ignore the edges in the network
+that the probability of having an edge is 0. Here, we also consider a model as
+an example that using relative clustering coefficient is better than global
+clustering coefficient for comparing networks and also checking the properties
+of the networks.",2106.05145v1
+2021-09-18,Enumeration of self-reciprocal irreducible monic polynomials with prescribed leading coefficients over a finite field,"A polynomial is called self-reciprocal (or palindromic) if the sequence of
+its coefficients is palindromic. In this paper we enumerate self-reciprocal
+irreducible monic polynomials over a finite field with prescribed leading
+coefficients. Asymptotic expression with explicit error bound is derived, which
+is used to show that such polynomials with degree $2n$ always exist provided
+that the number of prescribed leading coefficients is slightly less than $n/4$.
+Exact expressions are also obtained for fields with two or three elements and
+up to two prescribed leading coefficients.",2109.09006v3
+2021-10-13,High-Dimensional Varying Coefficient Models with Functional Random Effects,"We consider a sparse high-dimensional varying coefficients model with random
+effects, a flexible linear model allowing covariates and coefficients to have a
+functional dependence with time. For each individual, we observe discretely
+sampled responses and covariates as a function of time as well as time
+invariant covariates. Under sampling times that are either fixed and common or
+random and independent amongst individuals, we propose a projection procedure
+for the empirical estimation of all varying coefficients. We extend this
+estimator to construct confidence bands for a fixed number of varying
+coefficients.",2110.06426v1
+2021-10-15,Different coefficients for studying dependence,"Through computer simulations, we research several different measures of
+dependence, including Pearson's and Spearman's correlation coefficients, the
+maximal correlation, the distance correlation, a function of the mutual
+information called the information coefficient of correlation, and the maximal
+information coefficient (MIC). We compare how well these coefficients fulfill
+the criteria of generality, power, and equitability. Furthermore, we consider
+how the exact type of dependence, the amount of noise and the number of
+observations affect their performance.",2110.07928v2
+2022-04-13,On Signs of Fourier Coefficients of Hecke-Maass Cusp Forms on $\mathrm{GL}_3$,"We consider sign changes of Fourier coefficients of Hecke-Maass cusp forms
+for the group $\mathrm{SL}_3(\mathbb Z)$. When the underlying form is
+self-dual, we show that there are $\gg_\varepsilon X^{5/6-\varepsilon}$ sign
+changes among the coefficients $\{A(m,1)\}_{m\leq X}$ and that there is a
+positive proportion of sign changes for many self-dual forms. Similar result
+concerning the positive proportion of sign changes also hold for the
+real-valued coefficients $A(m,m)$ for generic $\mathrm{GL}_3$ cusp forms, a
+result which is based on a new effective Sato-Tate type theorem for a family of
+$\mathrm{GL}_3$ cusp forms we establish. In addition, non-vanishing of the
+Fourier coefficients is studied under the Ramanujan-Petersson conjecture.",2204.06261v1
+2022-06-07,On Binomial coefficients of real arguments,"As is well-known, a generalization of the classical concept of the factorial
+$n!$ for a real number $x\in {\mathbb R}$ is the value of Euler's gamma
+function $\Gamma(1+x)$. In this connection, the notion of a binomial
+coefficient naturally arose for admissible values of the real arguments.
+  By elementary means, it is proved a number of properties of binomial
+coefficients $\binom{r}{\alpha}$ of real arguments $r,\,\alpha\in {\mathbb R}$
+such as analogs of unimodality, symmetry, Pascal's triangle, etc. for classical
+binomial coefficients. The asymptotic behavior of such generalized binomial
+coefficients of a special form is established.",2206.03007v1
+2022-09-19,Fock expansion for two-electron atoms. High order angular coefficients,"The Fock expansion, which describes the properties of two-electron atoms near
+the nucleus, is studied. The angular Fock coefficients
+$\psi_{k,p}(\alpha,\theta)$ with the maximum possible value of subscript $p$
+are calculated on examples of the coefficients with $5\leq k \leq 10$. The
+presented technique makes it possible to calculate such angular coefficients
+for any arbitrarily large $k$. The mentioned coefficients being leading in the
+logarithmic power series representing the Fock expansion may be indispensable
+for the development of simple methods for calculating the helium-like
+electronic structure. The theoretical results obtained are verified by other
+suitable methods. The Wolfram Mathematica is used extensively.",2209.09053v2
+2022-09-23,Harmonic weak Maass forms and periods II,"In this paper we investigate the Fourier coefficients of harmonic Maass forms
+of negative half-integral weight. We relate the algebraicity of these
+coefficients to the algebraicity of the coefficients of certain canonical
+meromorphic modular forms of positive even weight with poles at Heegner
+divisors. Moreover, we give an explicit formula for the coefficients of
+harmonic Maass forms in terms of periods of certain meromorphic modular forms
+with algebraic coefficients.",2209.11454v1
+2023-03-03,Time fractional parabolic equations with partially SMO coefficients,"We present the unique solvability in Sobolev spaces of time fractional
+parabolic equations in divergence and non-divergence forms. The leading
+coefficients are merely measurable in $(t,x_1)$ for $a^{ij}$, $1 \leq i,j \leq
+d$, $(i,j) \neq (1,1)$. The coefficient $a^{11}$ is merely measurable locally
+either in $t$ or $x_1$. As functions of the remaining variables, the
+coefficients have small mean oscillations. We consider mixed norm Sobolev
+spaces with Muckenhoupt weights. Our results generalize previous work on
+parabolic equations with time fractional derivatives to a much larger class of
+coefficients and solution spaces.",2303.01688v1
+2023-03-22,Determining coefficients of thermoelastic system from boundary information,"Given a compact Riemannian manifold $(M,g)$ with smooth boundary $\partial
+M$, we give an explicit expression for full symbol of the thermoelastic
+Dirichlet-to-Neumann map $\Lambda_g$ with variable coefficients
+$\lambda,\mu,\alpha,\beta \in C^{\infty}(\bar{M})$. We prove that $\Lambda_g$
+uniquely determines partial derivatives of all orders of the coefficients on
+the boundary. Moreover, for a nonempty open subset $\Gamma\subset\partial M$,
+suppose that the manifold and the coefficients are real analytic up to
+$\Gamma$, we show that $\Lambda_g$ uniquely determines the coefficients on the
+whole manifold $\bar{M}$.",2303.12288v1
+2023-03-29,Unpredictable solutions of Duffing type equations with Markov coefficients,"The paper considers a stochastic differential equation of Duffing type with
+Markov coefficients. The existence of unpredictable solutions is considered.
+The unpredictability is a property of bounded functions characterized by
+unbounded sequences of moments of divergence and convergence in Bebutov
+dynamics. Markov components of the equation coefficients admit the
+unpredictability property. The components of the equation coefficients are
+derived from a Markov chain. The existence, uniqueness and exponential
+stability of an unpredictable solution are proved. The sequences of divergence
+and convergence of the coefficients and the solution are synchronized.
+Numerical example that support the theoretical results are provided.",2303.17336v1
+2023-06-04,Sharp coefficients bounds for Starlike functions associated with Gregory coefficients,"In this paper we introduced the class $\mathcal{S}_{G}^{\ast }$ of analytic
+functions which is related with starlike functions and generating function of
+Gregory coefficients. By using bounds on some coefficient functionals for the
+family of functions with positive real part, we obtain for functions in the
+class $\mathcal{S}_{G}^{\ast }$ several sharp coefficient bounds on the first
+six coeffcients and also further sharp bounds on the corresponding Hankel
+determinants.",2306.02431v1
+2023-11-07,Guts determine the leading coefficients of $L^2$-Alexander torsions,"For 3-manifolds, the leading coefficient of the $L^2$-Alexander torsion is a
+numerical invariant of a real first cohomology class. We show that the leading
+coefficient equals the relative $L^2$-torsion of the manifold cut up along a
+norm-minimizing surface dual to the cohomology class. Furthermore, the leading
+coefficient equals the relative $L^2$-torsion of the guts associated to the
+cohomology class. Finally, we prove that the leading coefficient is constant on
+any open Thurston cone. The main ingredients are a new criterion for the
+convergence of Fuglede-Kadison determinants and the work of Agol and Zhang on
+guts of 3-manifolds.",2311.04115v1
+2023-12-18,Asymptotic products of binomial and multinomial coefficients revisited,"In this note, we consider asymptotic products of binomial and multinomial
+coefficients and determine their asymptotic constants and formulas. Among them,
+special cases are the central binomial coefficients, the related Catalan
+numbers, and binomial coefficients in a row of Pascal's triangle. For the
+latter case, we show that it can also be derived from a limiting case of
+products of binomial coefficients over the rows. The asymptotic constants are
+expressed by known constants, for example, the Glaisher--Kinkelin constant. In
+addition, the constants lie in certain intervals that we determine precisely.
+Subsequently, we revisit a related result of Hirschhorn and clarify the given
+numerical constant by showing the exact expression.",2312.11369v1
+2024-03-27,Orthogonal Polynomials with a Singularly Perturbed Airy Weight,"We study the monic orthogonal polynomials with respect to a singularly
+perturbed Airy weight. By using Chen and Ismail's ladder operator approach, we
+derive a discrete system satisfied by the recurrence coefficients for the
+orthogonal polynomials. We find that the orthogonal polynomials satisfy a
+second-order linear ordinary differential equation, whose coefficients are all
+expressed in terms of the recurrence coefficients. By considering the time
+evolution, we obtain a system of differential-difference equations satisfied by
+the recurrence coefficients. Finally, we study the asymptotics of the
+recurrence coefficients when the degrees of the orthogonal polynomials tend to
+infinity.",2403.18669v1
+2012-10-01,Measurements of Antenna Surface for a Millimeter-Wave Space Radio Telescope II; Metal Mesh Surface for Large Deployable Reflector,"Large deployable antennas with a mesh surface woven by fine metal wires are
+an important technology for communications satellites and space radio
+telescopes. However, it is difficult to make metal mesh surfaces with
+sufficient radio-frequency (RF) performance for frequencies higher than
+millimeter waves. In this paper, we present the RF performance of metal mesh
+surfaces at 43 GHz. For this purpose, we developed an apparatus to measure the
+reflection coefficient, transmission coefficient, and radiative coefficient of
+the mesh surface. The reflection coefficient increases as a function of metal
+mesh surface tension, whereas the radiative coefficient decreases. The
+anisotropic aspects of the reflection coefficient and the radiative coefficient
+are also clearly seen. They depend on the front and back sides of the metal
+mesh surface and the rotation angle. The transmission coefficient was measured
+to be almost constant. The measured radiative coefficients and transmission
+coefficients would cause significant degradation of the system noise
+temperature. In addition, we carried out an astronomical observation of a
+well-known SiO maser source, R Cas, by using a metal mesh mirror on the NRO
+45-m radio telescope Coude system. The metal mesh mirror considerably increases
+the system noise temperature and slightly decreases the peak antenna
+temperature. These results are consistent with laboratory measurements.",1210.0335v1
+2018-11-14,A reduction principle for Fourier coefficients of automorphic forms,"We consider a general class of Fourier coefficients for an automorphic form
+on a finite cover of a reductive adelic group ${\bf
+G}(\mathbb{A}_{\mathbb{K}})$, associated to the data of a `Whittaker pair'. We
+describe a quasi-order on Fourier coefficients, and an algorithm that gives an
+explicit formula for any coefficient in terms of integrals and sums involving
+higher coefficients. The maximal elements for the quasi-order are
+`Levi-distinguished' Fourier coefficients, which correspond to taking the
+constant term along the unipotent radical of a parabolic subgroup, and then
+further taking a Fourier coefficient with respect to a
+$\mathbb{K}$-distinguished nilpotent orbit in the Levi quotient. Thus one can
+express any Fourier coefficient, including the form itself, in terms of higher
+Levi-distinguished coefficients. In follow-up papers we use this result to
+determine explicit Fourier expansions of minimal and next-to-minimal
+automorphic forms on split simply-laced reductive groups, and to obtain Euler
+product decompositions of their top Fourier coefficients.",1811.05966v5
+2020-07-04,Representations of coefficients of power series in classical statistical mechanics. Their classification and complexity criteria,"It is declared that the aim of simplifying representations of coefficients of
+power series of classical statistical mechanics is to simplify a process of
+obtaining estimates of the coefficients using their simplified representations.
+The aim of the article is: to formulate criteria for the complexity (from the
+above point of view) of representations of coefficients of the power series of
+classical statistical mechanics and to demonstrate their application by
+examples of comparing the Ree-Hoover representations of virial coefficients
+(briefly -- the RH representations) with such representations of power series
+coefficients that are based on the conception of the frame classification of
+labeled graphs (the abbreviation -- FC). To solve these problems, mathematical
+notions were introduced (such as a basic product, a basic integral, a basic
+linear combination, a basic linear combination with coefficients of
+insignificant complexity(the abbreviation -- BLC with CIC) and the
+classification of representations of the coefficients of power series of
+classical statistical mechanics is proposed. In the classification, the class
+of BLC's with CIC is the most important. It includes all the above
+representations of the coefficients of power series of classical statistical
+mechanics. Three criteria are formulated for estimate the comparative
+complexity of BLC's with CIC. These criteria are ordered by their accuracy.
+Based on each of these criteria, a criterion for the comparative complexity of
+finite sets of BLC's with CIC is constructed. The constructed criteria are
+ordered by their accuracy. The application of all the constructed criteria is
+demonstrated by examples of comparing RH representations with the
+representations of the power series coefficients based on the concept FC. The
+obtained results are presented in the tables and commented.",2007.02146v1
+2021-11-12,Histogram lies about distribution shape and Pearson's coefficient of variation lies about variability,"Background and Objective: Histograms and Pearson's coefficient of variation
+are among the most popular summary statistics. Researchers use histograms to
+judge the shape of quantitative data distribution by visual inspection. The
+coefficient of variation is taken as an estimator of relative variability of
+these data. We explore properties of histograms and coefficient of variation by
+examples in R, thus offering better alternatives: density plots and
+Eisenhauer's relative dispersion coefficient. Methods: Hypothetical examples
+developed in R are applied to create histograms and density plots, and to
+compute coefficient of variation and relative dispersion coefficient. Results:
+These hypothetical examples clearly show that these two traditional approaches
+are flawed. Histograms do not necessarily reflect the distribution of
+probabilities and the Pearson's coefficient of variation is not invariant with
+linear transformations and is not a measure of relative variability, for it is
+a ratio between a measure of absolute variability (standard deviation) and a
+measure of central position (mean). Potential alternatives are explained and
+applied for contrast. Conclusions: With the use of modern computers and R
+language it is easy to apply density plots, which are able to approximate the
+theoretical probability distribution. In addition, Eisenhauer's relative
+dispersion coefficient is suggested as a suitable estimator of relative
+variability, including sample size correction for lower and upper bounds.",2111.06822v3
+2023-02-19,Russel and Rao Coefficient is a Suitable Substitute for Dice Coefficient in Studying Restriction Mapped Genetic Distances of Escherichia coli,"Escherichia coli is one of many bacterial inhabitants found in human
+intestines and any adaptation as a result of mutations may affect its host. A
+commonly used technique employed to study these mutations is Restriction
+Fragment Length Polymorphism (RFLP) and is proceeded with a suitable distance
+coefficient to quantify genetic differences between 2 samples. Dice is
+considered a suitable distance coefficient in RFLP analyses, while others were
+left unstudied in its suitability for use. Hence, this study aims to identify
+substitutes for Dice. Experimental data was obtained by subculturing E. coli
+for 72 passages in 8 different adaptation media and RFLP profiles analyzed
+using 20 distance coefficients. Our results suggest that Dennis, Fossum,
+Matching and Russel and Rao to work as well or better than Dice. Dennis,
+Matching and Fossum coefficients had highest discriminatory abilities but are
+limited by the lack of upper or lower boundaries. Russel and Rao coefficient is
+highly correlated with Dice coefficient (r2 = 0.998), with both higher and
+lower boundaries, suggesting that Russel and Rao coefficient can be used to
+substitute Dice coefficient in studying genetic distances in E. coli.",2302.12714v1
+2023-11-27,turbo-RANS: Straightforward and Efficient Bayesian Optimization of Turbulence Model Coefficients,"Industrial simulations of turbulent flows often rely on Reynolds-averaged
+Navier-Stokes (RANS) turbulence models, which contain numerous closure
+coefficients that need to be calibrated. Although tuning these coefficients can
+produce significantly improved predictive accuracy, their default values are
+often used. We believe users do not calibrate RANS models for several reasons:
+there is no clearly recommended framework to optimize these coefficients; the
+average user does not have the expertise to implement such a framework; and,
+the optimization of the values of these coefficients can be a computationally
+expensive process. In this work, we address these issues by proposing a
+semi-automated calibration of these coefficients using a new framework based on
+Bayesian optimization. We introduce the generalized error and default
+coefficient preference (GEDCP) objective function, which can be used with
+integral, sparse, or dense reference data. We demonstrate the computationally
+efficient performance of turbo-RANS for three example cases: predicting the
+lift coefficient of an airfoil; predicting the velocity and turbulent kinetic
+energy fields for a separated flow; and, predicting the wall pressure
+coefficient distribution for flow through a converging-diverging channel. In
+the first two examples, we calibrate the $k$-$\omega$ shear stress transport
+(SST) turbulence model and, in the last example, we calibrate user-specified
+coefficients for the Generalized $k$-$\omega$ (GEKO) model in Ansys Fluent. An
+in-depth hyperparameter tuning study is conducted to recommend efficient
+settings for the turbo-RANS optimization procedure. Towards the goal of
+facilitating RANS turbulence closure model calibration, we provide an
+open-source implementation of the turbo-RANS framework that includes OpenFOAM,
+Ansys Fluent, and solver-agnostic templates for user application.",2311.15840v1
+1994-10-06,Damped Lyman Alpha Systems vs. Cold + Hot Dark Matter,"Damped Ly$\alpha$ systems provide possibly the most significant evidence for
+early structure formation, and thus a stringent constraint on the Cold + Hot
+Dark Matter (CHDM) cosmology. Using the numbers of halos in N-body simulations
+to normalize Press-Schechter (PS) estimates of the number densities of
+protogalaxies as a function of redshift, we find that CHDM with
+$\Omega_c/\Omega_\nu/\Omega_b = 0.6/0.3/0.1$ is compatible with the damped
+Ly$\alpha$ data only at $z<2.5$, but that it is probably incompatible with data
+at $z>3$. The predictions of CHDM are quite sensitive to the neutrino fraction.
+We find that $\Omega_c/\Omega_\nu/\Omega_b = 0.725/0.20/0.075$ is compatible
+with the $z>3$ data. With one massive neutrino species, this corresponds to
+lowering the neutrino mass from 7.0 to 4.7 eV, for $H_0=50\kmsMpc$ and
+$T=2.726$ K. By analysing our numerical simulations with different resolutions
+and box sizes as well as those of Ma \& Bertchinger (1994), we show that for
+the CHDM models with $\Omega_\nu$=0.2--0.3 the PS approximation should be used
+with Gaussian filter with $\delta_c=1.3-1.4$ if one tries to recover the total
+mass of a collapsed halo and to include nonlinear effects, due to waves both
+longer and shorter than those within the simulation box.",9410022v1
+1995-12-05,Small Scale Structure and High Redshift HI,"Cosmological simulations with gas dynamics suggest that the Lyman-alpha
+forest is produced mainly by ""small scale structure"" --- filaments and sheets
+that are the high redshift analog of today's galaxy superclusters. There is no
+sharp distinction between Lyman-alpha clouds and ""Gunn-Peterson"" absorption
+produced by the fluctuating IGM -- the Lyman-alpha forest {\it is} the
+Gunn-Peterson effect. Lyman limit and damped Lyman-alpha absorption arises in
+the radiatively cooled gas of forming galaxies. At $z~2-3$, most of the gas is
+in the photoionized, diffuse medium associated with the Lyman-alpha forest, but
+most of the {\it neutral} gas is in damped Lyman-alpha systems. We discuss
+generic evolution of cosmic gas in a hierarchical scenario of structure
+formation, with particular attention to the prospects for detecting 21cm
+emission from high redshift HI. A scaling argument based on the present-day
+cluster mass function suggests that objects with $M_{HI} >~ 5e11 h^{-1} \msun$
+should be extremely rare at $z~3$, so detections with existing instruments will
+be difficult. An instrument like the proposed Square Kilometer Array could
+detect individual damped Lyman-alpha systems at high redshift, making it
+possible to map structure in the high redshift universe in much the same way
+that today's galaxy redshift surveys map the local large scale structure.",9512016v1
+1996-04-03,APM z>4 QSO Survey: Spectra and Intervening Absorption Systems,"The APM multicolor survey for bright z > 4 objects, covering 2500 deg^2 of
+sky to m(R)~19, resulted in the discovery of thirty-one quasars with z > 4.
+High signal-to-noise optical spectrophotometry at 5A resolution has been
+obtained for the twenty-eight quasars easily accessible from the northern
+hemisphere. These spectra have been surveyed to create new samples of high
+redshift Lyman-limit systems, damped Lyman-alpha absorbers, and metal
+absorption systems (e.g. CIV and MgII). In this paper we present the spectra,
+together with line lists of the detected absorption systems. The QSOs display a
+wide variety of emission and absorption line characteristics, with 5 exhibiting
+broad absorption lines and one with extremely strong emission lines
+(BR2248-1242). Eleven candidate damped Ly-alpha absorption systems have been
+identified covering the redshift range 2.8<z<4.4 (8 with z>3.5). An analysis of
+the measured redshifts of the high ionization emission lines with the low
+ionization lines shows them to be blueshifted by 430+/-60 km/s. In a previous
+paper (Storrie-Lombardi et. al. 1994) we discussed the redshift evolution of
+the Lyman limit systems catalogued here. In subsequent papers we will discuss
+the properties of the Ly-alpha forest absorbers and the redshift and column
+density evolution of the damped Ly-alpha absorbers.",9604021v1
+1996-04-10,A Keck HIRES Investigation of the Metal Abundances and Kinematics of the z=2.46 Damped Lya System Toward Q0201+365,"We present high resolution ($\approx 8$ \kms) spectra of the QSO Q0201+365
+obtained with HIRES, the echelle spectrograph on the 10m W.M. Keck Telescope.
+Although we identify over $80\%$ of the absorption features and analyze several
+of the more complex metal-line systems, we focus our analysis on the damped
+\Lya system at $z=2.462$. Ionization simulations suggest the hydrogen in this
+system is significantly neutral and all of the observed metals are
+predominantly singly ionized. We measure accurate abundances for Fe, Cr, Si, Ni
+and place a lower limit on the abundance of Zn: [Fe/H] = $-0.830 \pm 0.051$,
+[Cr/H] = $-0.902 \pm 0.064$, [Si/H] = $-0.376 \pm 0.052$, [Ni/H] = $-1.002 \pm
+0.054$ and [Zn/H] $> -0.562 \pm 0.064$. We give evidence suggesting the actual
+Zn abundance is [Zn/H] $\approx -0.262$, implying the highest metallicity
+observed at a redshift $z \geq 2$. The relative abundances of these elements
+remains constant over essentially the entire system ($\approx 150$ \kms in
+velocity space), suggesting it is well mixed. Furthermore, we use the lack of
+abundance variations to infer properties of the dust responsible for element
+depletion. Finally, we discuss the kinematic characteristics of this damped
+\Lya system, comparing and contrasting it with other systems. The low-ion line
+profiles span $\approx 200$ \kms in velocity space and have an asymmetric shape
+with the strongest feature on the red edge. These kinematic characteristics are
+consistent with a rotating disk model.",9604042v1
+1996-06-13,Damping of Cosmic Magnetic Fields,"We examine the evolution of magnetic fields in an expanding fluid composed of
+matter and radiation with particular interest in the evolution of cosmic
+magnetic fields. We derive the propagation velocities and damping rates for
+relativistic and non-relativistic fast and slow magnetosonic, and Alfv\'en
+waves in the presence of viscous and heat conducting processes. The analysis
+covers all MHD modes in the radiation diffusion and the free-streaming regimes.
+When our results are applied to the evolution of magnetic fields in the early
+universe, we find that cosmic magnetic fields are damped from prior to the
+epoch of neutrino decoupling up to recombination. Our findings have multifold
+implications for cosmology. The dissipation of magnetic field energy into heat
+during the epoch of neutrino decoupling ensures that most magnetic field
+configurations generated in the very early universe satisfy big bang
+nucleosynthesis constraints. Further dissipation before recombination
+constrains models in which primordial magnetic fields give rise to galactic
+magnetic fields or density perturbations. Finally, the survival of Alfv\'en and
+slow magnetosonic modes on scales well below the Silk mass may be of
+significance for the formation of structure on small scales (abridged).",9606080v2
+1997-01-09,Molecular Hydrogen Absorption in the z= 1.97 Damped Lyman alpha Absorption system toward QSO 0013-004,"We present a new ultra-violet spectrum of the QSO 0013-004 with 0.9 \AA
+resolution obtained with the MMT Blue spectrograph. The \upsilon = 0 - 0, 1 -
+0, 2 - 0 and 3 - 0 Lyman bands of H_2 associated with the z = 1.9731 damped Ly
+alpah absorption line system have been detected. The H_2 column density is
+N(H_2) = 6.9 (\pm 1.6)\times 10^{19} cm^{-2}, and the Doppler parameter b =
+15\pm 2 km/s. The populations of different rotational levels are measured and
+used to derive the excitation temperatures. The estimated kinetic temperature
+T_K\sim 70 K, and the total particle number density n(H) \sim 300 cm^{-3}. The
+UV photoabsorption rate $\beta_0 \sim 6.7\times 10^{-9}$ s^{-1}, about a factor
+of few times greater than that in a typical diffuse Milky Way interstellar
+cloud. The total hydrogen column density is $N(H) = 6.4(\pm 0.5)\times 10^{20}
+cm^{-2}$. The fractional H_2 abundance f = 2N(H_2)/(2N(H_2) + N(H I)) \sim 0.22
+\pm 0.05 is the highest among all observed damped Ly\al absorbers. The high
+fractional H_2 abundance is consistent with the inferred presence of dust and
+strong C I absorption in this absorber.",9701041v1
+1997-02-06,Abundance Patterns of Heavy Elements in Damped Lyman-Alpha Galaxies,"We present a quantitative analysis of the abundances of heavy elements in
+damped Ly-alpha galaxies in the sample of Lu et al. (1996). In particular, we
+compare the observed gas-phase abundances with those expected when the
+intrinsic (i.e., nucleosynthetic) pattern is the same as that in either the Sun
+or in Galactic halo stars and when the depletion pattern is the same as that in
+the warm Galactic interstellar medium, but with various values of the
+dust-to-metals ratio. We find that the observations are equally consistent with
+the solar and halo-star intrinsic patterns and that they favor some depletion,
+the typical dust-to-metals ratio being 40%-90% of that in the Milky Way today.
+However, neither intrinsic pattern matches the observations perfectly. For the
+solar pattern, the discrepancy is mainly with [Mn/Fe], while for the halo-star
+pattern, the discrepancy is with [Zn/Fe], [Ni/Fe], and possibly [Al/Fe]. Our
+analysis does not support the claim by Lu et al. that the damped Ly-alpha
+galaxies have halo-star abundance patterns and no dust depletion.",9702066v2
+1997-08-04,"Violent Relaxation, Phase Mixing, and Gravitational Landau Damping","This paper proposes a geometric interpretation of flows generated by the
+collisionless Boltzmann equation (CBE), focusing on the coarse-grained approach
+towards equilibrium. The CBE is a noncanonical Hamiltonian system with the
+distribution function f the fundamental dynamical variable, the mean field
+energy H[f] playing the role of the Hamiltonian and the natural arena of
+physics being the infinite-dimensional phase space of distribution functions.
+Every time-independent equilibrium f_0 is an energy extremal with respect to
+all perturbations that preserve the constraints associated with Liouville's
+Theorem, local energy minima corresponding to linearly stable equilibria. If an
+initial f(t=0) is sufficiently close to some linearly stable lower energy f_0,
+its evolution involves linear phase space oscillations about f_0 which, in many
+cases, would be expected to exhibit linear Landau damping. If f(t=0) is far
+from any stable extremal, the flow will be more complicated but, in general,
+one would anticipate that the evolution involves nonlinear oscillations about
+some lower energy f_0. In this picture, the coarse-grained approach towards
+equilibrium usually termed violent relaxation is interpreted as nonlinear
+Landau damping. The evolution of a generic initial f(t=0) involves a coherent
+initial excitation, not necessarily small, being converted into incoherent
+motion associated with nonlinear oscillations about some equilibrium f_0 which,
+in general, will exhibit destructive interference.",9708026v1
+1998-11-23,The Physical Nature of the Lyman Limit Systems,"We analyze Keck HIRES observations of a Lyman limit system at z=2.652 toward
+Q2231-00. These observations afford the most comprehensive study of the
+physical properties of a LL system to date. By comparing the ionic column
+densities for Fe^+, Fe^{++}, Si^+, and Si^{3+} against calculations derived
+from the CLOUDY software package, we have strictly constrained the ionization
+state of this system. This has enabled us to calculate accurate abundances of a
+Lyman limit system for the first time at z > 2, e.g., [Fe/H] = -0.5 \pm 0.1. We
+also derive a total hydrogen column density, log N(H) = 20.73 \pm 0.2, which is
+comparable to values observed for the damped lya systems.
+  The system is special for exhibiting CII* 1335 absorption, allowing an
+estimate of the electron density, n_e = 6.5 \pm 1.3 x 10^{-2} cm^{-3}. Coupling
+this measurement with our knowledge of the ionization state, we derive the
+following physical properties: (1) hydrogen volume density, n_H = 5.9 \pm 1.2 x
+10^{-2} cm^{-3}, (2) path length, l = 3 \pm 1.6 kpc, and (3) ionizing
+intensity, log J_{912} = -20.22 \pm 0.21. We point out that a number of the
+physical properties (e.g. [Fe/H], N(H), n_H) resemble those observed for the
+damped lya systems, which suggests this system may be the photoionized analog
+of a damped system. The techniques introduced in this Letter should be
+applicable to a number of Lyman limit systems and therefore enable a survey of
+their chemical abundances and other physical properties.",9811357v1
+1998-12-03,Gravity-Modes in ZZ Ceti Stars III. Eigenvalues and Eigenfuctions,"We report on numerical calculations of nonadiabatic eigenvalues and
+eigenfunctions for g-modes in ZZ Ceti variables. The spectrum of overstable
+$l=1$ modes delineates the instability strip. Its blue edge occurs where
+$\omega \tau_c \approx 1$ for the $n=1$ mode. Here $\omega$ is radian frequency
+and $\tau_c$ is about four times the thermal timescale at the bottom of the
+surface convection zone. As a ZZ Ceti cools, its convection zone deepens,
+longer period modes become overstable, but the critical value of $\omega\tau_c$
+separating overstable and damped modes rises. The latter is a consequence of
+enhanced radiative damping for modes which propagate immediately below the
+convection zone. The critical value of $\omega\tau_c$ is of observational
+significance because modes with the smallest value of $\omega\tau_c$ are most
+observable photometrically. Maximum periods for overstable modes predicted for
+our cooler model envelopes are about a factor two longer than the observational
+upper limit of $1,200\s$. We assess a number of plausible resolutions for this
+discrepancy among which convective overshoot and nonlinear saturation look
+promising. The nonadiabatic eigenfunctions enable us to predict relative
+amplitudes and phases of photospheric variations of flux and velocity,
+quantities made accessible by recent observations. We also present asymptotic
+formula for damping rates of high order modes, a result of consequence for
+future investigations of nonlinear saturation of the amplidues of overstable
+modes.",9812085v1
+1999-01-19,"Collisionless Dissipative Nonlinear Alfven Waves: Nonlinear Steepening, Compressible Turbulence, and Particle Trapping","The magnetic energy of nonlinear Alfven waves in compressible plasmas may be
+ponderomotively coupled only to ion-acoustic quasi-modes which modulate the
+wave phase velocity and cause wave-front steepening. In the collisionless
+plasma with $\beta\not=0$, the dynamics of nonlinear Alfven wave is also
+affected by the resonant particle-wave interactions. Upon relatively rapid
+evolution (compared to the particle bounce time), the quasi-stationary wave
+structures, identical to the so called (Alfvenic) Rotational Discontinuities,
+form, the emergence and dynamics of which has not been previously understood.
+Collisionless (Landau) dissipation of nonlinear Alfven waves is also a
+plausible and natural mechanism of the solar wind heating. Considering a
+strong, compressible, Alfvenic turbulence as an ensemble of randomly
+interacting Alfvenic discontinuities and nonlinear waves, it is shown that
+there exist two distinct phases of turbulence. What phase realizes depends on
+whether this collisionless damping is strong enough to provide adequate energy
+sink at all scales and, thus, to support a steady-state cascade of the wave
+energy. In long-time asymptotics, however, the particle distribution function
+is affected by the wave magnetic fields. In this regime of nonlinear Landau
+damping, resonant particles are trapped in the quasi-stationary Alfvenic
+discontinuities, giving rise to a formation of a plateau on the distribution
+function and quenching collisionless damping. Using the virial theorem for
+trapped particles, it is analytically demonstrated that their effect on the
+nonlinear dynamics of such discontinuities is non-trivial and forces a
+significant departure of the theory from the conventional paradigm.",9901257v1
+2000-06-06,A Model of Metallicity Evolution in the Early Universe,"We apply the phenomenological model used to explain the abundances of Fe and
+r-process elements in very metal-poor stars in the Galaxy to [Fe/H] of damped
+Ly alpha systems. It is assumed that the first stars formed after the Big Bang
+were very massive and promptly enriched the interstellar medium to [Fe/H] ~ -3,
+at which metallicity formation of normal stars took over. Subsequent Fe
+enrichment was provided by Type II supernovae. The range of [Fe/H] at a given
+redshift z for damped Ly alpha systems is explained by the time t* after the
+Big Bang at which normal star formation started in an individual protogalactic
+system. The average t* is approx 80% the age of the universe for damped Ly
+alpha systems at z approx 1.5 to 4.5, indicating a long delay between the Big
+Bang and the turn-on of protogalaxies. It is inferred that a substantial
+fraction of the total baryonic matter may not have been aggregated into
+protogalaxies where normal star formation had occurred down to z ~ 1.5. The
+data near z = 2.2 suggest that the rate of turn-on of protogalaxies was
+initially very low and slowly reached a maximum at ~ 3 Gyr after the Big Bang.
+This may be important in understanding the rate of formation of quasars.",0006082v2
+2000-09-27,Lensing properties of 7 damped Lyman-alpha absorbing galaxy-QSO pairs,"Le Brun et al. (1997) presented the first identifications of the galaxies
+giving rise to 7 intermediate redshift damped Ly-alpha (DLA) absorption
+systems. Here, we study the gravitational lensing properties of these
+foreground galaxies based on their observed optical appearance and on the
+absence of any secondary lensed quasar image. We consider the possibility that
+any secondary image be hidden due to extinction by dust, but find it unlikely.
+We derive upper limits on the amplification factor affecting the luminosity of
+the background quasars; in each case, this factor is found to be less than 0.3
+mag. We also obtain upper limits on the total mass of the damped Ly-alpha
+galaxies, within radii equal to the quasar impact parameters. Mass-to-light
+ratios are found to be consistent with existing estimates based on X-ray
+emission or on motion of dwarf satellites. Although we show that lensing is not
+important in this sample, we note that existing DLA surveys used to determine
+the cosmological density of gas at z<1 are based on samples of quasars brighter
+than the ones considered here and for which the amplification bias is likely to
+be stronger.",0009433v1
+2000-11-14,Sharp HI edges at high z: the gas distribution from Damped Lyman-alpha to Lyman-limit absorption systems,"We derive the distribution of neutral and ionized gas in high redshift clouds
+which are optically thick to hydrogen ionizing radiation, using published data
+on Lyman-limit and Damped Lyman-alpha absorption systems in the redshift range
+1.75 < z < 3.25. We assume that the distribution of the hydrogen total (HI+HII)
+column density in the absorbers follows a power law K N_H^{-alpha}, whereas the
+observed HI column density distribution deviates from a pure power law as a
+result of ionization from a background radiation field. Comparison of the
+models and observations give Maximum Likelihood solutions for the exponent
+alpha and for X, the value of log(N_H/N_HI) when the Lyman-limit optical depth
+is unity: alpha=2.7^{+1.0}_{-0.7} and X=2.75\pm0.35. X is much lower than what
+would be obtained for a gaseous distribution in equilibrium under its own
+gravity but the ratio of dark matter to gas density is not well constrained
+being log(eta_0)=1.1\pm 0.8. An extrapolation of our derived power law
+distribution towards systems of lower column density, the Lyman-alpha forest,
+favours models with log(eta_0) < 1.1 and alpha=2.7-3.3. With alpha appreciably
+larger than 2, Lyman-limit systems contain more gas than Damped Lyman-alpha
+systems and Lyman-alpha forest clouds even more. Estimates of the cosmological
+gas and dark matter density due to absorbers of different column density around
+z=2.5 are also given.",0011268v1
+2000-11-29,Implications of 21cm observations for damped Ly-$α$ systems,"We present Giant Metrewave Radio Telescope HI 21cm absorption observations,
+of candidate and confirmed damped Lyman-$\alpha$ systems (DLAS). The derived
+spin temperatures (T_s) are in all cases $\sim 1000$ K or higher. We have also
+collated from the literature a list of DLAS for which 21cm observations exist,
+and discuss their implications for the nature of the absorbers.
+  A cross-comparison of the 21cm profiles with low ionization metal profiles
+shows that the 21cm absorption coincides in velocity with the deepest metal
+line feature. This is consistent with models in which the deep metal line
+features arise from discrete clouds but not with models where the deepest
+features are the result of velocity crowding.
+  We also find that the typical derived spin temperatures of DLAS are
+considerably higher than those in the Galaxy or nearby spirals. The only
+exceptions are DLAS which are known to be associated with the disks of spirals;
+these do, in fact, show low spin temperatures. In a multi-phase medium,the
+derived T_s is a weighted average of the temperatures of the individual phases.
+High derived T_s values are hence to be expected from small, low metallicity
+objects, since these objects should have a lower fraction of the cold phase in
+their ISM as compared to large galaxies. The high T_s in DLAS is hence
+consistent with their observed low metallicities as well as with recent
+observations that DLAS are also associated with dwarf/LSB galaxies. Finally, we
+suggest that the following trend may be identified: at low redshift, damped
+absorption arises from a range of systems, including spiral galaxy disks,
+while, at high redshift, absorption occurs predominantly in smaller systems.
+(Abridged)",0011540v1
+2001-01-18,A Comprehensive Statistical Analysis of the Gas Distribution in Lyman-limit and Damped Lyman-alpha Absorption Systems,"In this paper we show how to use data on Lyman-limit and Damped Lyman-alpha
+absorption systems to derive the hydrogen ionization fractions and the
+distribution of the face-on total gas column density. We consider axially
+symmetric, randomly oriented absorbers, ionized by an external background
+radiation field in order to relate the face-on total gas distribution to that
+of the neutral hydrogen observed along the line of sight. We devise a
+statistical procedure based on the Maximum Likelihood criterion, that is able
+to treat simultaneously data coming from different surveys and statistically
+recovers the ""true"" column densities in the presence of large uncertainties:
+this is especially important for Lyman-limit systems which leave an
+unmeasurable residual flux at wavelengths shorter than the Lyman break. We make
+use of simulated data to look for possible observational biases and extensively
+test our procedure. For a large statistical sample of real data in the redshift
+range [1.75,3.25] (collected from all published surveys) our Maximum Likelihood
+procedure gives a power-law slope for the total hydrogen distribution of -2.7.
+All together Lyman-limit systems therefore contain more gas than Damped
+Lyman-alpha systems. Analysis of data at other redshifts shows that more
+observations are needed to reach a compelling evidence for a cosmological
+evolution of the slope of the gas distribution.",0101335v1
+2001-04-29,The First Detection of Co in a Damped Lyman Alpha System,"The study of elemental abundances in Damped Lyman Alpha systems (DLAs) at
+high redshift represents one of our best opportunities to probe galaxy
+formation and chemical evolution at early times. By coupling measurements made
+in high z DLAs with our knowledge of abundances determined locally and with
+nucleosynthetic models, we can start to piece together the star formation
+histories of these galaxies. Here, we discuss the clues to galactic chemical
+evolution that may be gleaned from studying the abundance of Co in DLAs. We
+present high resolution echelle spectra of two QSOs, Q2206-199 and Q1223+17,
+both already known to exhibit intervening damped systems. These observations
+have resulted in the first ever detection of Co at high redshift, associated
+with the z= 1.92 DLA in the sightline towards Q2206-199. We find that the
+abundance of Co is approximately 1/4 solar and that there is a clear
+overabundance relative to iron, [Co/Fe] = +0.31 +/- 0.05. From the abundance of
+Zn, we determine that this is a relatively metal-rich DLA, with a metallicity
+approximately 1/3 solar. Therefore, this first detection of Co is similar to
+the marked overabundance relative to Fe seen in Galactic bulge and thick disk
+stars.",0104466v1
+2001-06-22,Self-Absorption of Ionizing Radiation and Extended Lyman Alpha Emission in High- Redshift QSOs,"We calculate the neutral hydrogen column density of self-absorption in QSOs
+predicted in a model where the QSOs are located in the same halos that contain
+the gas in damped Lya absorption systems. The model is parameterized by the
+probability P_0 that any halo has an active QSO. We assume that the QSOs ionize
+the gas, but do not expel or heat it. The derived HI column densities produce
+negligible Lyman limit absorption, even in the lowest luminosity QSOs, with an
+optical depth of only ~ 10% for luminosity L=0.01 L_*, when P_0=10^{-2}. We
+also compute the HeII Lyman limit self-absorption, which is slightly higher but
+still negligible. The self-absorption can be higher if the gas is highly
+clumped; only in this case the overall emissivity from QSOs could be
+significantly reduced due to absorption by the known damped Lya systems, to
+affect the predicted intensity of the ionizing background or the epoch of HeII
+reionization. The presence of the gas associated with damped absorption systems
+around QSOs could also be detected from the narrow Lya emission line, which
+should have and angular extent of 0.1 to 1'' in typical high-redshift QSOs.",0106424v2
+2001-06-22,Compressible MHD Turbulence in Interstellar Plasmas,"Radio-wave scintillation observations reveal a nearly Kolmogorov spectrum of
+density fluctuations in the ionized interstellar medium. Although this density
+spectrum is suggestive of turbulence, no theory relevant to its interpretation
+exists. We calculate the density spectrum in turbulent magnetized plasmas by
+extending the theory of incompressible MHD turbulence given by Goldreich &
+Sridhar to include the effects of compressibility and particle transport. Our
+most important results are as follows. (1) Density fluctuations are due to the
+slow mode and the entropy mode. Both modes are passively mixed by the cascade
+of shear Alfven waves. Since the shear Alfven waves have a Kolmogorov spectrum,
+so do the density fluctuations. (2) Observed density fluctuation amplitudes
+imply either that the magnetic and gas pressures are comparable, or that the
+outer scale of the turbulence is very small. (3) A high degree of ionization is
+required for the cascade to survive damping by neutrals and thereby to extend
+to small lengthscales. Regions that are insufficiently ionized produce density
+fluctuations only on lengthscales larger than the neutral damping scale. These
+regions may account for the excess of power that is found on large scales. (4)
+Both the entropy mode and the slow mode are damped on lengthscales below that
+at which protons can diffuse across an eddy during the eddy's turnover time.
+Consequently, eddies whose extents along the magnetic field are smaller than
+the proton collisional mean free path do not contribute to the density
+spectrum. However, in MHD turbulence eddies are highly elongated along the
+magnetic field. From an observational perspective, the relevant lengthscale is
+that transverse to the magnetic field. Thus the cut-off lengthscale for density
+fluctuations is significantly smaller than the proton mean free path.",0106425v1
+2001-11-20,Collisional Cascades in Planetesimal Disks I. Stellar Flybys,"We use a new multiannulus planetesimal accretion code to investigate the
+evolution of a planetesimal disk following a moderately close encounter with a
+passing star. The calculations include fragmentation, gas and
+Poynting-Robertson drag, and velocity evolution from dynamical friction and
+viscous stirring. We assume that the stellar encounter increases planetesimal
+velocities to the shattering velocity, initiating a collisional cascade in the
+disk. During the early stages of our calculations, erosive collisions damp
+particle velocities and produce substantial amounts of dust. For a wide range
+of initial conditions and input parameters, the time evolution of the dust
+luminosity follows a simple relation, L_d/L_{\star} = L_0 / [alpha +
+(t/t_d)^{beta}]. The maximum dust luminosity L_0 and the damping time t_d
+depend on the disk mass, with L_0 proportional to M_d and t_d proportional to
+M_d^{-1}. For disks with dust masses of 1% to 100% of the `minimum mass solar
+nebula' (1--100 earth masses at 30--150 AU), our calculations yield t_d approx
+1--10 Myr, alpha approx 1--2, beta = 1, and dust luminosities similar to the
+range observed in known `debris disk' systems, L_0 approx 10^{-3} to 10^{-5}.
+Less massive disks produce smaller dust luminosities and damp on longer
+timescales. Because encounters with field stars are rare, these results imply
+that moderately close stellar flybys cannot explain collisional cascades in
+debris disk systems with stellar ages of 100 Myr or longer.",0111384v1
+2002-02-11,The Contribution of HI-rich Galaxies to the Damped Lyman-alpha Absorber Population at z=0,"We present a study of the expected properties of the low redshift damped
+Lyman-alpha absorber population determined from a sample of HI-selected
+galaxies in the local universe. Because of a tight correlation between the HI
+mass and HI cross-section, which we demonstrate spans all galaxy types, we can
+use our HI-selected sample to predict the properties of the absorption line
+systems. We use measurements of the number density and HI cross-section of
+galaxies to show that the total HI cross-section at column densities sufficient
+to produce damped Lyman-alpha absorption is consistent with no evolution of the
+absorber population. We also find that the dN/dz distribution is dominated by
+galaxies with HI masses near 10^9 Msolar. However, because of the large
+dispersion in the correlation between HI mass and stellar luminosity, we find
+that the distribution of dN/dz as a function of L_J is fairly flat.
+Additionally, we examine the line widths of the HI-selected galaxies and show
+that there may be evolution in the kinematics of HI-rich galaxies, but it is
+not necessary for the higher redshift population to contain a greater
+proportion of high mass galaxies than we find locally.",0202216v2
+2002-03-18,Monte Carlo Simulation of Lyman Alpha Scattering and Application to Damped Lyman Alpha Systems,"A Monte Carlo code to solve the transfer of Lyman alpha (Lya) photons is
+developed, which can predict the Lya image and two-dimensional Lya spectra of a
+hydrogen cloud with any given geometry, Lya emissivity, neutral hydrogen
+density distribution, and bulk velocity field. We apply the code to several
+simple cases of a uniform cloud to show how the Lya image and emitted line
+spectrum are affected by the column density, internal velocity gradients, and
+emissivity distribution. We then apply the code to two models for damped Lya
+absorption systems: a spherical, static, isothermal cloud, and a flattened,
+axially symmetric, rotating cloud. If the emission is due to fluorescence of
+the external background radiation, the Lya image should have a core
+corresponding to the region where hydrogen is self-shielded. The emission line
+profile has the characteristic double peak with a deep central trough. We show
+how rotation of the cloud causes the two peaks to shift in wavelength as the
+slit is perpendicular to the rotation axis, and how the relative amplitude of
+the two peaks is changed. In reality, damped Lya systems are likely to have a
+clumpy gas distribution with turbulent velocity fields, which should smooth the
+line emission profile, but should still leave the rotation signature of the
+wavelength shift across the system.",0203287v2
+2002-04-09,The Non-Damped Nature of Twelve Low-Redshift Damped Lyman Alpha Candidate Systems,"Hubble Space Telescope (HST) UV spectroscopy of 12 candidate low-redshift
+damped Lyman alpha (DLA) systems in 11 QSOs (z=0.103 in Q0054+144, z=0.969 and
+z=0.987 in Q0302-223, z=0.478 in Q0454-220, z=1.476 in Q1047+550, z=1.070 in
+Q1206+459, z=1.228 in Q1247+267, z=0.399 in Q1318+290B, z=0.519 in Q1329+412,
+z=0.276 in Q1451-375, z=0.204 in Q2112+059, z=0.263 in Q2251+113) are
+presented; the observations demonstrate that they are not DLAs with
+$N(HI)\ge2\times10^{20}$ atoms cm$^{-2}$. In all cases except two the systems
+either do not exist or are well below the DLA threshold column density; the
+exceptions are a z=0.474 system in Q0454-220 which has $N(HI)=3\times10^{19}$
+atoms cm$^{-2}$ and a z=1.223 system in Q1247+267 which has
+$N(HI)=8\times10^{19}$ atoms cm$^{-2}$. Despite the availability of data in the
+HST archives demonstrating that these are not suitable targets, many have
+unfortunately been approved for observation with Chandra, Gemini, and/or HST
+with the intent of doing followup work on low-redshift DLAs. Furthermore, these
+results indicate that the low-redshift DLA statistics derived from IUE spectra
+and presented by Lanzetta, Wolfe, & Turnshek (1995) and Wolfe et al. (1995) are
+invalid.",0204155v1
+2002-05-17,High matter density peaks from UVES observations of QSO pairs: correlation properties and chemical abundances,"We study the transverse clustering properties of high matter density peaks as
+traced by high column density absorption systems (either Lyman limit systems
+characterized by N(HI)> 2 x 10^{17} cm^{-2} or CIV systems with W_{r}> 0.5 A)
+at redshifts between 2 and 3 with UVES spectra of two QSO pairs (UM680/UM681 at
+56 arcsec angular separation and Q2344+1228/Q2343+1232 at 5 arcmin angular
+separation) and a QSO triplet (Q2139-4433/Q2139-4434/Q2138-4427 at 1, 7 and 8
+arcmin angular separation). We find 3 damped Ly-alpha systems (N(HI)> 2 x
+10^{20} cm^{-2}): 2 coinciding with strong metal systems in the nearby line of
+sight and 1 matching the emission redshift of the paired QSO; plus 7 Lyman
+limit systems: 4 forming two matching couples and 3 without a corresponding
+metal system within ~3000 km/s in the coupled line of sight. In summary, we
+detect five out of ten matching systems within 1000 km/s, indicating a highly
+significant overdensity of strong absorption systems over separation lengths
+from ~1 to 8 h^{-1} Mpc. The observed coincidences could arise in gas due to
+starburst-driven superwinds associated with a quasar or a galaxy, or gas
+belonging to large scale structures like filaments or sheets. We also determine
+chemical abundance ratios for three damped Ly-alpha systems. In particular, for
+the damped system at z ~ 2.53788 in the spectrum of Q2344+1228, new estimates
+of the ratios O/Fe, C/Fe are obtained: [C/Fe]<0.06, [O/Fe]<0.2. They indicate
+that O and C are not over-solar in this system.",0205299v1
+2002-08-28,Complex rotation with internal dissipation. Applications to cosmic-dust alignment and to wobbling comets and asteroids,"Neutron stars, asteroids, comets, cosmic-dust granules, spacecraft, as well
+as whatever other freely spinning body dissipate energy when they rotate about
+any axis different from principal. We discuss the internal-dissipation-caused
+relaxation of a freely precessing rotator towards its minimal-energy mode (mode
+that corresponds to the spin about the maximal-inertia axis). While the body
+nutates at some rate, the internal stresses and strains within the body
+oscillate at frequencies both higher and lower than this rate. The internal
+dissipation takes place mostly the second and higher harmonics. We discuss the
+application of our findings to asteroids. Regarding the comets, estimates show
+that the currently available angular resolution of spacecraft-based instruments
+makes it possible to observe wobble damping within year- or maybe even
+month-long spans of time. We also discuss cosmic-dust astrophysics; in
+particular, the role played by precession damping in the dust alignment. We
+show that this damping provides coupling of the grain's rotational and
+vibrational degrees of freedom; this entails occasional flipping of dust grains
+due to thermal fluctuations. During such a flip, grain preserves its angular
+momentum, but the direction of torques arising from H2 formation reverses. As a
+result, flipping grain will not rotate fast in spite of the action of
+uncompensated H2 formation torques. The grains get ``thermally trapped,'' and
+their alignment is marginal.",0208489v1
+2003-06-16,Damping of Tensor Modes in Cosmology,"An analytic formula is given for the traceless transverse part of the
+anisotropic stress tensor due to free streaming neutrinos, and used to derive
+an integro-differential equation for the propagation of cosmological
+gravitational waves. The solution shows that anisotropic stress reduces the
+squared amplitude by 35.6 % for wavelengths that enter the horizon during the
+radiation-dominated phase, independent of any cosmological parameters. This
+decreases the tensor temperature and polarization correlation functions for
+these wavelengths by the same amount. The effect is less for wavelengths that
+enter the horizon at later times. At the longest wavelengths the decrease in
+the tensor correlation functions due to neutrino free streaming ranges from
+10.7% for $\Omega_Mh^2=0.1$ to 9.0% for $\Omega_Mh^2=0.15$. An Appendix gives a
+general proof that tensor as well as scalar modes satisfy a conservation law
+for perturbations outside the horizon, even when the anisotropic stress tensor
+is not negligible.",0306304v2
+2003-12-30,Nonlinear Pulsations in Differentially Rotating Neutron Stars: Mass-Shedding-Induced Damping and Splitting of the Fundamental Mode,"We study small-amplitude, nonlinear pulsations of uniformly and
+differentially rotating neutron stars employing a two-dimensional evolution
+code for general-relativistic hydrodynamics. Using Fourier transforms at
+several points inside the star, both the eigenfrequencies and two-dimensional
+eigenfunctions of pulsations are extracted. The centrifugal forces and the
+degree of differential rotation have significant effects on the
+mode-eigenfunction. We find that near the mass-shedding limit, the pulsations
+are damped due to shocks forming at the surface of the star. This new damping
+mechanism may set a small saturation amplitude for modes that are unstable to
+the emission of gravitational waves. After correcting for the assumption of the
+Cowling approximation (used in our numerical code), we construct empirical
+relations that predict the range of gravitational-wave frequencies from
+quasi-periodic post-bounce oscillations in the core collapse of massive stars.
+We also find that the fundamental quasi-radial mode is split, at least in the
+Cowling approximation and mainly in differentially rotating stars, into two
+different sequences.",0312648v2
+2004-01-16,Simulating stochastically excited oscillations. The mode lifetime of xi Hya,"The discovery of solar-like oscillations in the giant star xy Hya (G7III) was
+reported by Frandsen et al. (2002). Their frequency analysis was very limited
+due to alias problems in the data set (caused by single-site observations). The
+extent to which the aliasing affected their analysis was unclear due to the
+unknown damping time of the stellar oscillation modes. In this paper we
+describe a simulator created to generate time series of stochastically excited
+oscillations, which takes as input an arbitrary window function and includes
+both white and non-white noise. We also outline a new method to compare a large
+number of simulated time series with an observed time series to determine the
+damping time, amplitude, and limited information on the degree of the
+stochastically excited modes. For xi Hya we find the most likely amplitude to
+be ~ 2 m/s, in good agreement with theory (Houdek & Gough, 2002), and the most
+likely damping time to be ~ 2 days, which is much shorter than the theoretical
+value of 15-20 days calculated by Houdek & Gough (2002).",0401331v1
+2004-10-13,On the Importance of Local Sources of Radiation in Cosmological Absorption Systems,"An upper limit to the importance of local sources of radiation compared to
+the cosmic background in cosmological absorption systems is derived, as a
+simple consequence of the conservation of surface brightness. The limit depends
+only on the rate of incidence of the absorbers and the mean free path of the
+radiation. It is found that, on average, the ionizing radiation intensity from
+local sources in Lyman limit systems at z>2 must be less than half of the
+intensity of the cosmic background. In absorbers with column densities much
+lower than Lyman limit systems, the local source contribution must be
+negligible. The limit on the ratio of local source to background intensities is
+then applied to the class of damped Lya absorption systems with detectable
+excited CII lines. A cooling rate of the gas in these systems has been measured
+by Wolfe et al., who assumed that the balancing heating source is photoelectric
+heating on dust by light at ~ 1500 A . The intensity from local star formation
+at this wavelength in this class of damped Lya systems is found to be at most ~
+3 times the background intensity. If the heating source is indeed photoelectric
+heating of dust, the background created by sources associated with damped Lya
+systems can then be estimated from the average cooling rates measured in the
+absorbers. Current results yield a background intensity higher than previous
+estimates based on observed galaxy and quasar luminosity functions, although
+with a large uncertainty. The possibility of other sources of heating, such as
+shock-heating in a turbulent medium, should be explored.",0410315v1
+2005-04-04,Relativistic r-modes and Shear viscosity: regularizing the continuous spectrum,"Within a fully relativistic framework, we derive and solve numerically the
+perturbation equations of relativistic stars, including the stresses produced
+by a non-vanishing shear viscosity in the stress-energy tensor. With this
+approach, the real and imaginary parts of the frequency of the modes are
+consistently obtained. We find that, approaching the inviscid limit from the
+finite viscosity case, the continuous spectrum is regularized and we can
+calculate the quasi-normal modes for stellar models that do not admit solutions
+at first order in perturbation theory when the coupling between the polar and
+axial perturbations is neglected. The viscous damping time is found to agree
+within factor 2 with the usual estimate obtained by using the eigenfunctions of
+the inviscid limit and some approximation for the energy dissipation integrals.
+We find that the frequencies and viscous damping times for relativistic
+$r-$modes lie between the Newtonian and Cowling results. We compare the results
+obtained with homogeneous, polytropic and realistic equations of state and find
+that the frequencies depend only on the rotation rate and on the compactness
+parameter (M/R), being almost independent of the equation of state. Our
+numerical results for realistic neutron stars give viscous damping times with
+the same dependence on mass and radius as previously estimated, but
+systematically larger of about 60%.",0504062v1
+2005-04-29,Evidence for a magnitude-dependent bias in the Hamburg/ESO Survey for Damped Lyman-alpha Systems,"We present preliminary results from the Hamburg/ESO survey for Damped
+Ly-alpha (hereafter, DLA) Systems. This survey is characterized by (i) the good
+knowledge of the biases affecting the parent QSO survey, (ii) the brightness
+and (iii) the relatively wide magnitude distribution of the background QSOs.
+Therefore, it is well-suited to study possible magnitude-dependent biases in
+DLA surveys, such as the one expected from dust obscuration. We have
+systematically searched for damped Lyman-alpha line candidates in 5 A
+resolution spectra of the 188 QSOs that constitute our statistical sample.
+These candidates have later been reobserved with UVES at the ESO--Very Large
+Telescope (VLT) for confirmation and accurate N(HI) measurements. In the
+redshift range covered by the survey, 19 DLA systems have been discovered. Over
+the whole survey, we find that the number density, n(z), and cosmological
+density of gas, Omega_gas, have comparable values to the ones obtained by
+CORALS (Ellison et al. 2001). However, the number densities of DLA systems n(z)
+in two sub-samples of equal absorption distance path defined by the magnitude
+of the background QSOs differ by a factor of about 5. We estimate that the
+probability that n(z) is equal in the two sub-samples is < 0.003. A similar,
+only slightly less significant difference is found for Omega_gas.",0504657v1
+2005-07-06,The free precession and libration of Mercury,"An analysis based on the direct torque equations including tidal dissipation
+and a viscous core-mantle coupling is used to determine the damping time scales
+of O(10^5) years for free precession of the spin about the Cassini state and
+free libration in longitude for Mercury. The core-mantle coupling dominates the
+damping over the tides by one to two orders of magnitude for the plausible
+parameters chosen. The short damping times compared with the age of the solar
+system means we must find recent or on-going excitation mechanisms if such free
+motions are found by the current radar experiments or the future measurement by
+the MESSENGER and BepiColombo spacecraft that will orbit Mercury. We also show
+that the average precession rate is increased by about 30% over that obtained
+from the traditional precession constant because of a spin-orbit resonance
+induced contribution by the C_{22} term in the expansion of the gravitational
+field. The C_{22} contribution also causes the path of the spin during the
+precession to be slightly elliptical with a variation in the precession rate
+that is a maximum when the obliquity is a minimum. An observable free
+precession will compromise the determination of obliquity of the Cassini state
+and hence of C/MR^2 for Mercury, but a detected free libration will not
+compromise the determination of the forced libration amplitude and thus the
+verification of a liquid core",0507117v1
+2005-10-12,Ly-alpha Radiative Transfer in Cosmological Simulations and Application to a z~8 Emitter,"We develop a Ly-alpha radiative transfer (RT) Monte Carlo code for
+cosmological simulations.High resolution,along with appropriately treated
+cooling can result in simulated environments with very high optical
+depths.Thus,solving the Ly-alpha RT problem in cosmological simulations can
+take an unrealistically long time.For this reason,we develop methods to speed
+up the Ly-alpha RT.With these accelerating methods,along with the
+parallelization of the code,we make the problem of Ly-alpha RT in the complex
+environments of cosmological simulations tractable.We test the RT code against
+simple Ly-alpha emitter models,and then we apply it to the brightest Ly-alpha
+emitter of a gasdynamics+N-body Adaptive Refinement Tree (ART) simulation at
+z~8.We find that recombination rather than cooling radiation Ly-alpha photons
+is the dominant contribution to the intrinsic Ly-alpha luminosity of the
+emitter,which is ~4.8x10e43 ergs/s.The size of the emitter is pretty
+small,making it unresolved for currently available instruments.Its spectrum
+before adding the Ly-alpha Gunn-Peterson absorption (GP) resembles that of
+static media,despite some net inward radial peculiar motion.This is because for
+such high optical depths as those in ART simulations,velocities of order some
+hundreds km/s are not important.We add the GP in two ways.First we assume no
+damping wing,corresponding to the situation where the emitter lies within the
+HII region of a very bright quasar,and second we allow for the damping
+wing.Including the damping wing leads to a maximum line brightness suppression
+by roughly a factor of ~62.The line fluxes,even though quite faint for current
+ground-based telescopes,should be within reach for JWST.",0510347v2
+2005-12-05,Kinematics and star formation activity in the z=2.03954 damped Lyman-alpha system towards PKS 0458-020,"We present UVES observations of the log N(HI)= 21.7 damped Lyman-alpha system
+at z=2.03954 towards the quasar PKS 0458-020. HI Lyman-alpha emission is
+detected in the center of the damped Lyman-alpha absorption trough.
+Metallicities are derived for MgII, SiII, PII, CrII, MnII, FeII and ZnII and
+are found to be -1.21\pm0.12, -1.28\pm0.20, -1.54\pm0.11, -1.66\pm0.10,
+-2.05\pm0.11, -1.87\pm0.11, -1.22\pm0.10, respectively, relative to solar. The
+depletion factor is therefore of the order of [Zn/Fe]=0.65. We observe metal
+absorption lines to be blueshifted compared to the Lyman-alpha emission up to a
+maximum of 100 and 200 km/s for low and high-ionization species respectively.
+This can be interpreted either as the consequence of rotation in a large
+(~7kpc) disk or as the imprint of a galactic wind. The star formation rate
+(SFR) derived from the Lyman-alpha emission, 1.6 solar masses/yr, is compared
+with that estimated from the observed CII* absorption. No molecular hydrogen is
+detected in our data, yielding a molecular fraction f<-6.52. This absence of H2
+can be explained as the consequence of a high ambient UV flux which is one
+order of magnitude larger than the radiation field in the ISM of our Galaxy and
+originates in the observed emitting region.",0512118v1
+2006-02-14,On the magnetic structure and wind parameter profiles of Alfven wave driven winds in late-type supergiant stars,"Cool stars at giant and supergiant evolutionary phases present low velocity
+and high density winds, responsible for the observed high mass-loss rates.
+Although presenting high luminosities, radiation pressure on dust particles is
+not sufficient to explain the wind acceleration process. Among the possible
+solutions to this still unsolved problem, Alfven waves are, probably, the most
+interesting for their high efficiency in transfering energy and momentum to the
+wind. Typically, models of Alfven wave driven winds result in high velocity
+winds if they are not highly damped. In this work we determine
+self-consistently the magnetic field geometry and solve the momentum, energy
+and mass conservation equations, to demonstrate that even a low damped Alfven
+wave flux is able to reproduce the low velocity wind. We show that the magnetic
+fluxtubes expand with a super-radial factor S>30 near the stellar surface,
+larger than that used in previous semi-empirical models. The rapid expansion
+results in a strong spatial dilution of the wave flux. We obtained the wind
+parameter profiles for a typical supergiant star of 16 M_sun. The wind is
+accelerated in a narrow region, coincident with the region of high divergence
+of the magnetic field lines, up to 100 km/s. For the temperature, we obtained a
+slight decrease near the surface for low damped waves, because the wave heating
+mechanism is less effective than the radiative losses. The peak temperature
+occurs at 1.5 r_0 reaching 6000 K. Propagating outwards, the wind cools down
+mainly due to adiabatic expansion.",0602305v1
+2006-03-17,Electron impact excitation of Helium-like ions up to n=4 levels including radiation damping,"Helium-like ions provide the most important X-ray spectral diagnostics in
+high temperature fusion and astrophysical plasmas. We previously presented
+computed collision strengths for O~VII including relativistic fine structure,
+levels up to the $n=4$ complex and radiation damping of autoionizing
+resonances. We have extended this work to other He-like ions (N, Ne, Mg, Al,
+Si, S, Ca). The calculations are carried out using the Breit-Pauli R-matrix
+(BPRM) method with a 31-level eigenfunction expansion. Collision strengths for
+the principal lines important in X-ray plasma diagnostics, w, x, y and z,
+corresponding to the 4 transitions to the ground level 1s^2(^1S_0) <-
+1s2p(^1P^o_1), 1s2p(^3P^o_2), 1s2p(^3P^o_1), 1s2s(^3S_1), are explicitly shown.
+We find the effect of radiation damping to be significant for the forbidden
+transitions in heavier He-like ions, which should affect the diagnostic line
+ratios. We extrapolated the collision strengths to their values at infinite
+energy using the Burgess-Tully extrapolation technique. This is required to
+calculate the Maxwellian average collision strengths at high temperature. We
+show that the coupling between dipole allowed and inter-combination transitions
+affects increasingly the effective collision strengths for the n ^1S_0 - n'
+^3P_1 transition as the charge of the ion increases. This clearly affects the
+treatment of the extrapolation toward the infinite energy point of the
+collision strength. This work is carried out as part of the Iron Project-RmaX
+Network.",0603482v1
+2006-07-25,Metal-rich Damped/sub-Damped Lyman-alpha Quasar Absorbers at z<1,"Damped Lyman-alpha absorbers (DLAs), seen in absorption against a background
+quasar, provide the most detailed probes available of element abundances in the
+Universe over > 90 % of its age. DLAs can be used to observationally measure
+the global mean metallicity in the Universe and its evolution with time.
+Paradoxically, these observations are more difficult at lower redshifts, where
+the absorber rest-frame UV spectra are cut-off due to the atmospheric
+absorption. We present here high-resolution VLT/UVES observations of several
+elements contained in three DLAs and one sub-DLA with 0.6<z_abs<0.9. We detect
+Mg I, Mg II, Fe II, Zn II, Cr II, Mn II, Ti II and Ca II. Our observations more
+than double the high-resolution sample of [Zn/H] at z<1. We also report the
+discovery of three metal-rich systems, whereas most previous measurements show
+low N(HI)-weighted mean metallicity projecting to about 1/6th solar level at
+z=0. We derive [Zn/H]=-0.11+/-0.04 at z_abs=0.725, [Zn/H]=-0.54+/-0.20 at
+z_abs=0.740 and [Zn/H]=-0.49+/-0.22 at z_abs=0.652, plus one additional upper
+limit ([Zn/H]<-0.36 at z_abs=0.842). These measurements confirm the existence
+of quasar absorbers with relatively high metallicities based on abundance
+estimates free from the effect of dust depletion. Possible implications of
+these results for the metallicity of neutral gas phase in the past ~ 8 Gyr are
+presented and compared with models.",0607561v1
+1994-09-29,Avalanches in the Weakly Driven Frenkel-Kontorova Model,"A damped chain of particles with harmonic nearest-neighbor interactions in a
+spatially periodic, piecewise harmonic potential (Frenkel-Kontorova model) is
+studied numerically. One end of the chain is pulled slowly which acts as a weak
+driving mechanism. The numerical study was performed in the limit of infinitely
+weak driving. The model exhibits avalanches starting at the pulled end of the
+chain. The dynamics of the avalanches and their size and strength distributions
+are studied in detail. The behavior depends on the value of the damping
+constant. For moderate values a erratic sequence of avalanches of all sizes
+occurs. The avalanche distributions are power-laws which is a key feature of
+self-organized criticality (SOC). It will be shown that the system selects a
+state where perturbations are just able to propagate through the whole system.
+For strong damping a regular behavior occurs where a sequence of states
+reappears periodically but shifted by an integer multiple of the period of the
+external potential. There is a broad transition regime between regular and
+irregular behavior, which is characterized by multistability between regular
+and irregular behavior. The avalanches are build up by sound waves and shock
+waves. Shock waves can turn their direction of propagation, or they can split
+into two pulses propagating in opposite directions leading to transient
+spatio-temporal chaos. PACS numbers: 05.70.Ln,05.50.+q,46.10.+z",9409006v1
+1998-06-21,Collective intersubband transitions in quantum wells: a comparative density-functional study,"We use time-dependent (current) density functional theory to study collective
+transitions between the two lowest subbands in GaAs/AlGaAs quantum wells. We
+focus on two systems where experimental results are available: a wide single
+and a narrow asymmetric double well. The aim is to calculate frequency and
+linewidth of collective electronic modes damped via electron-electron
+interaction only. Since Landau damping is not effective here, the dominant
+damping mechanism involves dynamical exchange-correlation effects such as
+multipair production. To capture these effects, one has to go beyond the widely
+used adiabatic local density approximation (ALDA) and include retardation. We
+perform a comparative study of two approaches which fall in this category: the
+dynamical extension of the ALDA by Gross and Kohn, and a more recent method
+which treats exchange and correlation beyond the ALDA as viscoelastic stresses
+in the electron liquid. We find that the former method is more robust: it
+performs similarly for strongly different degrees of collectivity of the
+electronic motion. Results for quantum wells compare reasonably to experiment,
+with a tendency towards overdamping. By contrast, the viscoelastic approach is
+superior for systems where the electron dynamics is predominantly collective,
+but breaks down if the local velocity field is too rapidly varying, as in the
+case of a single-electron-like behavior such as tunneling through a potential
+barrier.",9806252v1
+1998-11-27,Renormalization group analysis of the quantum non-linear sigma model with a damping term,"We investigate the behavior of the zero-temperature quantum non-linear sigma
+model in d dimensions in the presence of a damping term of the form f(w)~
+|w|^alpha, with 1 \le alpha <2. We find two fixed points: a spin-wave fixed
+point FP1 showing a dynamic scaling exponent z=1 and a dissipative fixed point
+FP2 with z>1. In the framework of the \epsilon-expansion it is seen that there
+is a range of values alpha_*(d) \le alpha \le 2 where the point FP1 is stable
+with respect to FP2, so that the system realizes a z=1 quantum critical
+behavior even in the presence of a dissipative term. However, reasonable
+arguments suggest that in d=2 this range is very narrow. In the broken symmetry
+phase we discuss a phenomenological scaling approach, treating damping as a
+perturbation of the ordered ground state. The relation of these results with
+the pseudogap effect observed in underdoped layered cuprates is discussed.",9811392v2
+1999-12-14,Spinwave damping in the two-dimensional ferromagnetic XY model,"The effect of damping of spinwaves in a two-dimensional classical
+ferromagnetic XY model is considered. The damping rate $\Gamma_{q}$ is
+calculated using the leading diagrams due to the quartic-order deviations from
+the harmonic spin Hamiltonian. The resulting four-dimensional integrals are
+evaluated by extending the techniques developed by Gilat and others for
+spectral density types of integrals. $\Gamma_{q}$ is included into the memory
+function formalism due to Reiter and Solander, and Menezes, to determine the
+dynamic structure function $S(q,\omega)$. For the infinite sized system, the
+memory function approach is found to give non-divergent spinwave peaks, and a
+smooth nonzero background intensity (``plateau'' or distributed intensity) for
+the whole range of frequencies below the spinwave peak. The background
+amplitude relative to the spinwave peak rises with temperature, and eventually
+becomes higher than the spinwave peak, where it appears as a central peak. For
+finite-sized systems, there are multiple sequences of weak peaks on both sides
+of the spinwave peaks whose number and positions depend on the system size and
+wavevector in integer units of $2\pi/L$. These dynamical finite size effects
+are explained in the memory function analysis as due to either spinwave
+difference processes below the spinwave peak or sum processes above the
+spinwave peak. These features are also found in classical Monte Carlo --
+Spin-Dynamics simulations.",9912241v1
+2002-01-25,Time-dependent current density functional theory for the linear response of weakly disordered systems,"This paper develops a quantitatively accurate first-principles description
+for the frequency and the linewidth of collective electronic excitations in
+inhomogeneous weakly disordered systems. A finite linewidth in general has
+intrinsic and extrinsic sources. At low temperatures and outside the region
+where electron-phonon interaction occurs, the only intrinsic damping mechanism
+is provided by electron-electron interaction. This kind of intrinsic damping
+can be described within time-dependent density-functional theory (TDFT), but
+one needs to go beyond the adiabatic approximation and include retardation
+effects. It was shown previously that a density-functional response theory that
+is local in space but nonlocal in time has to be constructed in terms of the
+currents, rather than the density. This theory will be reviewed in the first
+part of this paper. For quantitatively accurate linewidths, extrinsic
+dissipation mechanisms, such as impurities or disorder, have to be included. In
+the second part of this paper, we discuss how extrinsic dissipation can be
+described within the memory function formalism. We first review this formalism
+for homogeneous systems, and then present a synthesis of TDFT with the memory
+function formalism for inhomogeneous systems, to account simultaneously for
+intrinsic and extrinsic damping of collective excitations. As example, we
+calculate frequencies and linewidths of intersubband plasmons in a 40 nm wide
+GaAs/AlGaAs quantum well.",0201483v1
+2004-05-14,Thermoelastic relaxation in elastic structures with applications to thin plates,"A new result enables direct calculation of thermoelastic damping in vibrating
+elastic solids. The mechanism for energy loss is thermal diffusion caused by
+inhomogeneous deformation, flexure in thin plates. The general result is
+combined with the Kirchhoff assumption to obtain a new equation for the
+flexural vibration of thin plates incorporating thermoelastic loss as a damping
+term. The thermal relaxation loss is inhomogeneous and depends upon the local
+state of vibrating flexure, specifically, the principal curvatures at a given
+point on the plate. Thermal loss is zero at points where the principal
+curvatures are equal and opposite, that is, saddle shaped or pure anticlastic
+deformation. Conversely, loss is maximum at points where the curvatures are
+equal, that is, synclastic or spherical flexure. The influence of modal
+urvature on the thermoelastic damping is described through a modal
+pparticipation factor. The effect of transverse thermal diffusion on plane wave
+propagation is also examined. It is shown that transverse diffusion effects are
+always small provided the plate thickness is far greater than the thermal
+phonon mean free path, a requirement for the validity of the classical theory
+of heat transport. These results generalize Zener's theory of thermoelastic
+loss in beams and are useful in predicting mode widths in MEMS and NEMS
+oscillators.",0405323v2
+2005-04-21,Ultrafast dynamics of coherent optical phonons and nonequilibrium electrons in transition metals,"The femtosecond optical pump-probe technique was used to study dynamics of
+photoexcited electrons and coherent optical phonons in transition metals Zn and
+Cd as a function of temperature and excitation level. The optical response in
+time domain is well fitted by linear combination of a damped harmonic
+oscillation because of excitation of coherent $E_{2g}$ phonon and a
+subpicosecond transient response due to electron-phonon thermalization. The
+electron-phonon thermalization time monotonically increases with temperature,
+consistent with the thermomodulation scenario, where at high temperatures the
+system can be well explained by the two-temperature model, while below
+$\approx$ 50 K the nonthermal electron model needs to be applied. As the
+lattice temperature increases, the damping of the coherent $E_{2g}$ phonon
+increases, while the amplitudes of both fast electronic response and the
+coherent $E_{2g}$ phonon decrease. The temperature dependence of the damping of
+the $E_{2g}$ phonon indicates that population decay of the coherent optical
+phonon due to anharmonic phonon-phonon coupling dominates the decay process. We
+present a model that accounts for the observed temperature dependence of the
+amplitude assuming the photoinduced absorption mechanism, where the signal
+amplitude is proportional to the photoinduced change in the quasiparticle
+density. The result that the amplitude of the $E_{2g}$ phonon follows the
+temperature dependence of the amplitude of the fast electronic transient
+indicates that under the resonant condition both electronic and phononic
+responses are proportional to the change in the dielectric function.",0504540v1
+2005-10-10,Quantum master equation descriptions of a nanomechanical resonator coupled to a single-electron transistor,"We analyse the quantum dynamics of a nanomechanical resonator coupled to a
+normal-state single-electron transistor (SET). Starting from a microscopic
+description of the system, we derive a master equation for the SET island
+charge and resonator which is valid in the limit of weak electro-mechanical
+coupling. Using this master equation we show that, apart from brief transients,
+the resonator always behaves like a damped harmonic oscillator with a shifted
+frequency and relaxes into a thermal-like steady state. Although the behaviour
+remains qualitatively the same, we find that the magnitude of the resonator
+damping rate and frequency shift depend very sensitively on the relative
+magnitudes of the resonator period and the electron tunnelling time. Maximum
+damping occurs when the electrical and mechanical time-scales are the same, but
+the frequency shift is greatest when the resonator moves much more slowly than
+the island charge. We then derive reduced master equations which describe just
+the resonator dynamics. By making slightly different approximations, we obtain
+two different reduced master equations for the resonator. Apart from minor
+differences, the two reduced master equations give rise to a consistent picture
+of the resonator dynamics which matches that obtained from the master equation
+including the SET island charge.",0510236v1
+2005-10-16,Magnetic vortex dynamics in a 2D easy plane ferromagnet,"In this thesis, we consider the dynamics of vortices in the easy plane
+insulating ferromagnet in two dimensions. In addition to the quasiparticle
+excitations, here spin waves or magnons, this magnetic system admits a family
+of vortex solutions carrying two topological invariants, the winding number or
+vorticity, and the polarization. A vortex is approximately described as a
+particle moving about the system, endowed with an effective mass and acted upon
+by a variety of forces. Classically, the vortex has an inter-vortex potential
+energy giving a Coulomb-like force (attractive or repulsive depending on the
+relative vortex vorticity), and a gyrotropic force, behaving as a self-induced
+Lorentz force, whose direction depends on both topological indices. Expanding
+semiclassically about a many-vortex solution, the vortices are quantized by
+considering the scattered magnon states, giving a zero point energy correction
+and a many-vortex mass tensor. The vortices cannot be described as independent
+particles--that is, there are off-diagonal mass terms, such as 1/2 Mij vi vj,
+that are non-negligible. This thesis examines the full vortex dynamics in
+further detail by evaluating the Feynman-Vernon influence functional, which
+describes the evolution of the vortex density matrix after the magnon modes
+have been traced out. In addition to the set of forces already known, we find
+new damping forces acting both longitudinally and transversely to the vortex
+motion. The vortex motion within a collective cannot be entirely separated:
+there are damping forces acting on one vortex due to the motion of another. The
+effective damping forces have memory effects: they depend not only on the
+current motion of the vortex collection but also on the motion history.",0510414v1
+2006-05-19,Enhancement of noncontact friction between closely spaced bodies by two-dimensional systems,". We consider the effect of an external bias voltage and the spatial
+variation of the surface potential, on the damping of cantilever vibrations.
+The electrostatic friction is due to energy losses in the sample created by the
+electromagnetic field from the oscillating charges induced on the surface of
+the tip by the bias voltage and spatial variation of the surface potential. A
+similar effect arises when the tip is oscillating in the electrostatic field
+created by charged defects in a dielectric substrate. The electrostatic
+friction is compared with the van der Waals friction originating from the
+fluctuating electromagnetic field due to quantum and thermal fluctuation of the
+current density inside the bodies. We show that the electrostatic and van der
+Waals friction can be greatly enhanced if on the surfaces of the sample and the
+tip there are two-dimension (2D) systems, e.g. a 2D-electron system or
+incommensurate layers of adsorbed ions exhibiting acoustic vibrations. We show
+that the damping of the cantilever vibrations due to the electrostatic friction
+may be of similar magnitude as the damping observed in recent experiments of
+Stipe \textit{et al} [B.C.Stipe, H.J.Mamin, T.D.Stowe, T.W.Kenny, and D.Rugar,
+Phys.Rev. Lett.% \textbf{87}, 0982001]. We also show that at short separation
+the van der Waals friction may be large enough to be measured experimentally.",0605480v1
+2006-09-12,Slowing down Josephson vortex lattice in Bi_2Sr_2CaCu_2O_{8+d} with pancake vortices,"We study theoretically and experimentally influence of pancake vortices on
+motion of the Josephson vortex lattice in layered high-temperature
+superconductors. Mobility of the Josephson vortices in layered superconductors
+is strongly suppressed by small amount of pancake-vortex stacks. Moving
+Josephson vortex lattice forces oscillating zigzag deformation of the
+pancake-vortex stacks contributing to damping. The salient feature of this
+contribution is its nonmonotonic dependence on the lattice velocity and the
+corresponding voltage. Maximum pancake effect is realized when the Josephson
+frequency matches the relaxation frequency of the stacks. The pancake-vortex
+damping is strongly suppressed by thermal fluctuations of the pancake vortices.
+This theoretical picture was qualitatively confirmed by experiments on two
+mesas prepared out of Bi_2Sr_2CaCu_2O_{8+d} whiskers. We found that the
+Josephson-vortex flux-flow voltage is very sensitive to small c-axis magnetic
+field. The pancake-vortex contribution to the current indeed nonmonotonically
+depends on voltage and decreases with increasing temperature and in-plane
+magnetic field. We also found that irradiation with heavy ions has no
+noticeable direct influence on motion of the Josephson vortices but
+dramatically reduces the pancake-vortex contribution to the damping of the
+Josephson vortex lattice at low temperatures.",0609262v2
+2003-08-24,Numerical analysis of quasinormal modes in nearly extremal Schwarzschild-de Sitter spacetimes,"We calculate high-order quasinormal modes with large imaginary frequencies
+for electromagnetic and gravitational perturbations in nearly extremal
+Schwarzschild-de Sitter spacetimes. Our results show that for low-order
+quasinormal modes, the analytical approximation formula in the extremal limit
+derived by Cardoso and Lemos is a quite good approximation for the quasinormal
+frequencies as long as the model parameter $r_1\kappa_1$ is small enough, where
+$r_1$ and $\kappa_1$ are the black hole horizon radius and the surface gravity,
+respectively. For high-order quasinormal modes, to which corresponds
+quasinormal frequencies with large imaginary parts, on the other hand, this
+formula becomes inaccurate even for small values of $r_1\kappa_1$. We also find
+that the real parts of the quasinormal frequencies have oscillating behaviors
+in the limit of highly damped modes, which are similar to those observed in the
+case of a Reissner-Nordstr{\"" o}m black hole. The amplitude of oscillating
+${\rm Re(\omega)}$ as a function of ${\rm Im}(\omega)$ approaches a non-zero
+constant value for gravitational perturbations and zero for electromagnetic
+perturbations in the limit of highly damped modes, where $\omega$ denotes the
+quasinormal frequency. This means that for gravitational perturbations, the
+real part of quasinormal modes of the nearly extremal Schwarzschild-de Sitter
+spacetime appears not to approach any constant value in the limit of highly
+damped modes. On the other hand, for electromagnetic perturbations, the real
+part of frequency seems to go to zero in the limit.",0308077v4
+2006-02-01,Radiation Damping in Einstein-Aether Theory,"This work concerns the loss of energy of a material system due to
+gravitational radiation in Einstein-aether theory-an alternative theory of
+gravity in which the metric couples to a dynamical, timelike, unit-norm vector
+field. Derived to lowest post-Newtonian order are waveforms for the metric and
+vector fields far from a nearly Newtonian system and the rate of energy
+radiated by the system. The expressions depend on the quadrupole moment of the
+source, as in standard general relativity, but also contain monopolar and
+dipolar terms. There exists a one-parameter family of Einstein-aether theories
+for which only the quadrupolar contribution is present, and for which the
+expression for the damping rate is identical to that of general relativity to
+the order worked to here. This family cannot yet be declared observationally
+viable, since effects due to the strong internal fields of bodies in the actual
+systems used to test the damping rate are not included.",0602004v5
+1998-02-20,Real-time Relaxation and Kinetics in Hot Scalar QED: Landau Damping,"The real time evolution of field condensates with soft length scales
+k^{-1}>(eT)^{-1} is solved in hot scalar electrodynamics, with a view towards
+understanding relaxational phenomena in the QGP and the electroweak plasma. We
+find that transverse gauge invariant non-equilibrium expectation values of
+fields relax via {\em power laws} to asymptotic amplitudes that are determined
+by the quasiparticle poles. The long time relaxational dynamics and relevant
+time scales are determined by the behaviour of the retarded self-energy not at
+the small frequencies, but at the Landau damping thresholds. This explains the
+presence of power laws and not of exponential decay. Furthermore, we derive the
+influence functional, the Langevin equation and the fluctuation-dissipation
+theorem for the soft modes, identifying the correlation functions that emerge
+in the classical limit. We show that a Markovian approximation fails to
+describe the dynamics {\em both} at short and long times. We also introduce a
+novel kinetic approach that goes beyond the standard Boltzmann equation and
+incorporates off-shell processes and find that the distribution function for
+soft quasiparticles relaxes with a power law through Landau damping. We also
+find an unusual dressing dynamics of bare particles and anomalous (logarithmic)
+relaxation of hard quasiparticles.",9802370v2
+2003-03-04,Asymptotic quasinormal modes of Reissner-Nordström and Kerr black holes,"According to a recent proposal, the so-called Barbero-Immirzi parameter of
+Loop Quantum Gravity can be fixed, using Bohr's correspondence principle, from
+a knowledge of highly-damped black hole oscillation frequencies. Such
+frequencies are rather difficult to compute, even for Schwarzschild black
+holes. However, it is now quite likely that they may provide a fundamental link
+between classical general relativity and quantum theories of gravity. Here we
+carry out the first numerical computation of very highly damped quasinormal
+modes (QNM's) for charged and rotating black holes. In the Reissner-Nordstr\""om
+case QNM frequencies and damping times show an oscillatory behaviour as a
+function of charge. The oscillations become faster as the mode order increases.
+At fixed mode order, QNM's describe spirals in the complex plane as the charge
+is increased, tending towards a well defined limit as the hole becomes
+extremal. Kerr QNM's have a similar oscillatory behaviour when the angular
+index $m=0$. For $l=m=2$ the real part of Kerr QNM frequencies tends to
+$2\Omega$, $\Omega$ being the angular velocity of the black hole horizon, while
+the asymptotic spacing of the imaginary parts is given by $2\pi T_H$.",0303029v3
+1997-11-17,Fusion and Binary-Decay Mechanisms in the $^{35}$Cl+$^{24}$Mg System at E/A $\approx$ 8 MeV/Nucleon,"Compound-nucleus fusion and binary-reaction mechanisms have been investigated
+for the $^{35}$Cl+$^{24}$Mg system at an incident beam energy of E$_{Lab}$= 282
+MeV. Charge distributions, inclusive energy spectra, and angular distributions
+have been obtained for the evaporation residues and the binary fragments.
+Angle-integrated cross sections have been determined for evaporation residues
+from both the complete and incomplete fusion mechanisms. Energy spectra for
+binary fragment channels near to the entrance-channel mass partition are
+characterized by an inelastic contribution that is in addition to a fully
+energy damped component. The fully damped component which is observed in all
+the binary mass channels can be associated with decay times that are comparable
+to, or longer than the rotation period. The observed mass-dependent cross
+sections for the fully damped component are well reproduced by the fission
+transition-state model, suggesting a fusion followed by fission origin. The
+present data cannot, however, rule out the possibility that a long-lived
+orbiting mechanism accounts for part or all of this yield.",9711005v1
+1996-12-31,Fluid Models for Kinetic Effects on Coherent Nonlinear Alfven Waves. II. Numerical Solutions,"The influence of various kinetic effects (e.g. Landau damping, diffusive and
+collisional dissipation, and finite Larmor radius terms) on the nonlinear
+evolution of finite amplitude Alfvenic wave trains in a finite-beta environment
+is systematically investigated using a novel, kinetic nonlinear Schrodinger
+(KNLS) equation. The dynamics of Alfven waves is sensitive to the sense of
+polarization as well as the angle of propagation with respect to the ambient
+magnetic field. Numerical solution for the case with Landau damping reveals the
+formation of dissipative structures, which are quasi-stationary, S-polarized
+directional (and rotational) discontinuities which self-organize from parallel
+propagating, linearly polarized waves. Parallel propagating circularly
+polarized packets evolve to a few circularly polarized Alfven harmonics on
+large scales. Stationary arc-polarized rotational discontinuities form from
+obliquely propagating waves. Collisional dissipation, even if weak, introduces
+enhanced wave damping when beta is very close to unity. Cyclotron motion
+effects on resonant particle interactions introduce cyclotron resonance into
+the nonlinear Alfven wave dynamics.",9612018v1
+2000-09-06,"Design, fabrication and measurement of the first rounded damped detuned accelerator structure (RDDS1)","As a joint effort in the JLC/NLC research program, we have developed a new
+type of damped detuned accelerator structure with optimized round-shaped
+cavities (RDDS). This paper discusses some important R&D aspects of the first
+structure in this series (RDDS1). The design aspects covered are the cell
+design with sub-MHz precision, HOM detuning, coupling and damping technique and
+wakefield simulation. The fabrication issues covered are ultra-precision cell
+machining with micron accuracy, assembly and diffusion bonding technologies to
+satisfactorily meet bookshelf, straightness and cell rotational alignment
+requirements. The measurements described are the RF properties of single
+cavities and complete accelerator section, as well as wakefields from the ASSET
+tests at SLAC. Finally, future improvements are also discussed.",0009025v1
+2001-07-19,Dipole Wakefield Suppression In High Phase Advance Detuned Linear Accelerators For The JLC/NLC Designed To Minimise Electrical Breakdown And Cumulative BBU,"Recent experiments at SLAC [1,2] and CERN [3] have revealed evidence of
+significant deformation in the form of ""pitting"" of the cells of the 1.8m
+series of structures DDS/RDDS (Damped Detuned Structure/Rounded Damped Detuned
+Structure). This pitting occurs in the high group velocity (vg /c = 0.012) end
+of the accelerating structure and little evidence of breakdown has been found
+in the lower group velocity end of the structure. Additional, albeit
+preliminary experimental evidence, suggests that shorter and lower group
+velocity structures have reduced breakdown events with increasing accelerating
+field strengths. Two designs are presented here, firstly a 90cm structure
+consisting of 83 cells with an initial vg/c = 0.0506 (known as H90VG5) and
+secondly, an even shorter structure of length 60cm consisting of 55 cells with
+an initial vg /c = 0.03 (known as H60VG3). The feasibility of using these
+structures to accelerate a charged beam over 10km is investigated. The
+particular issue focussed upon is suppression of the dipole wakefields via
+detuning of the cell frequencies and by locally damping individual cells in
+order to avoid BBU (Beam Break Up). Results are presented on beam-induced
+dipole wakefields and on the beam dynamics encountered on tracking the progress
+of the beam through several thousand accelerating structures.
+  [1] C. Adolphsen, ROAA003, this conf. [2] R.H. Miller et al, FPAH062, this
+conf. [3] L. Groening et al, MPPH039, this conf",0107049v1
+2000-12-10,Chaotic atomic population oscillations between two coupled Bose-Einstein condensates with time-dependent asymmetric trap potential,"We have investigated the chaotic atomic population oscillations between two
+coupled Bose-Einstein condensates (BEC) with time-dependent asymmetric trap
+potential. In the perturbative regime, the population oscillations can be
+described by the Duffing equation, and the chaotic oscillations near the
+separatrix solution are analyzed. The sufficient-necessary conditions for
+stable oscillations depend on the physical parameters and initial conditions
+sensitively. The first-order necessary condition indicates that the Melnikov
+function is equal to zero, so the stable oscillations are Melnikov chaotic. For
+the ordinary parameters and initial conditions, the chaotic dynamics is
+simulated with numerical calculation. If the damping is absent, with the
+increasing of the trap asymmetry, the regular oscillations become chaotic
+gradually, the corresponding stroboscopic Poincare sections (SPS) vary from a
+single island to more islands, and then the chaotic sea. For the completely
+chaotic oscillations, the long-term localization disappears and the short-term
+localization can be changed from one of the BECs to the other through the route
+of Rabi oscillation. When there exists damping, the stationary chaos
+disappears, the transient chaos is a common phenomenon before regular stable
+frequency locked oscillations. And proper damping can keep localization
+long-lived.",0012043v1
+2003-01-23,Revivals and entanglement from initially entangled mixed states of a damped Jaynes-Cummings model,"An exact density matrix of a phase-damped Jaynes - Cummings model (JCM) with
+entangled Bell-like initial states formed from a model two-state atom and sets
+of adjacent photon number states of a single mode radiation field is presented.
+The entanglement of the initial states and the subsequent time evolution is
+assured by finding a positive lower bound on the concurrence of local 2x2
+projections of the full 2xinfinity JCM density matrix. It is found that the
+time evolution of the lower bound of the concurrence systematically captures
+the corresponding collapse and revival features in atomic inversion, relative
+entropies of atomic and radiation, mutual entropy, and quantum deficit. The
+atom and radiation subsystems exhibit alternating sets of collapses and
+revivals in a complementary fashion due to the initially mixed states of the
+atom and radiation employed here. This is in contrast with the result obtained
+when the initial state of the dissipationless system is a factored pure state
+of atom and radiation, where the atomic and radiation entropies are necessarily
+the same. The magnitudes of the entanglement lower bound and the atomic and
+radiation revivals become larger as both magnitude and phase of the Bell-like
+initial state contribution increases. The time evolution of the entropy
+difference of the total system and that of the radiation subsystem exhibits
+negative regions called ""supercorrelated"" states which do not appear in the
+atomic subsystem. Entangled initial states are found to enhance this
+supercorrelated feature. Finally, the effect of phase damping is to randomize
+both the subsystems for asymptotically long times .",0301126v1
+2003-03-18,A Method for Modeling Decoherence on a Quantum Information Processor,"We develop and implement a method for modeling decoherence processes on an
+N-dimensional quantum system that requires only an $N^2$-dimensional quantum
+environment and random classical fields. This model offers the advantage that
+it may be implemented on small quantum information processors in order to
+explore the intermediate regime between semiclassical and fully quantum models.
+We consider in particular $\sigma_z\sigma_z$ system-environment couplings which
+induce coherence (phase) damping, though the model is directly extendable to
+other coupling Hamiltonians. Effective, irreversible phase-damping of the
+system is obtained by applying an additional stochastic Hamiltonian on the
+environment alone, periodically redressing it and thereby irreversibliy
+randomizing the system phase information that has leaked into the environment
+as a result of the coupling. This model is exactly solvable in the case of
+phase-damping, and we use this solution to describe the model's behavior in
+some limiting cases. In the limit of small stochastic phase kicks the system's
+coherence decays exponentially at a rate which increases linearly with the kick
+frequency. In the case of strong kicks we observe an effective decoupling of
+the system from the environment. We present a detailed implementation of the
+method on an nuclear magnetic resonance quantum information processor.",0303115v1
+2005-11-25,The electrodynamic 2-body problem and the origin of quantum mechanics,"We numerically solve the functional differential equations (FDE's) of
+2-particle electrodynamics, using the full electrodynamic force obtained from
+the retarded Lienard-Wiechert potentials and the Lorentz force law. In
+contrast, the usual formulation uses only the Coulomb force (scalar potential),
+reducing the electrodynamic 2-body problem to a system of ordinary differential
+equations (ODE's). The ODE formulation is mathematically suspect since FDE's
+and ODE's are known to be incompatible; however, the Coulomb approximation to
+the full electrodynamic force has been believed to be adequate for physics. We
+can now test this long-standing belief by comparing the FDE solution with the
+ODE solution, in the historically interesting case of the classical hydrogen
+atom. The solutions differ.
+  A key qualitative difference is that the full force involves a `delay'
+torque. Our existing code is inadequate to calculate the detailed interaction
+of the delay torque with radiative damping. However, a symbolic calculation
+provides conditions under which the delay torque approximately balances (3rd
+order) radiative damping. Thus, further investigations are required, and it was
+prematurely concluded that radiative damping makes the classical hydrogen atom
+unstable. Solutions of FDE's naturally exhibit an_infinite_ spectrum of
+_discrete_ frequencies. The conclusion is that (a) the Coulomb force is_not_ a
+valid approximation to the full electrodynamic force, so that (b) the n-body
+interaction needs to be reformulated in various current contexts such as
+molecular dynamics.",0511235v1
+2007-05-11,Ground-state cooling of a micromechanical oscillator: generalized framework for cold damping and cavity-assisted cooling schemes,"We provide a general framework to describe cooling of a micromechanical
+oscillator to its quantum ground state by means of radiation-pressure coupling
+with a driven optical cavity. We apply it to two experimentally realized
+schemes, back-action cooling via a detuned cavity and cold-damping
+quantum-feedback cooling, and we determine the ultimate quantum limits of both
+schemes for the full parameter range of a stable cavity. While both allow to
+reach the oscillator's quantum ground state, we find that back-action cooling
+is more efficient in the good cavity limit, i.e. when the cavity bandwidth is
+smaller than the mechanical frequency, while cold damping is more suitable for
+the bad cavity limit. The results of previous treatments are recovered as
+limiting cases of specific parameter regimes.",0705.1728v6
+2007-11-08,Solving non-linear equations of longitudinal and transverse electron waves in collisionless Maxwellian plasma,"We have considered an expansion of solutions of the non-linear equations for
+both longitudinal and transverse waves in collisionless Maxwellian plasma in
+series of non-damping overtones of the field E(x,t) and electron velocity
+distribution function f=f(0) +f(1) where f(0) is background Maxwellian electron
+distribution function and f(1) is perturbation. The electrical field and
+perturbation f(1) are presented as a series of non-damping harmonics with
+increasing frequencies of the order n and the same propagation speed. It is
+shown presence of recurrent relations for arising overtones. Convergence of the
+series is provided by a power law parameter series convergence. There are
+proposed also successive procedures of cutting off the distribution function
+f(1) to the condition of positivity f near the singularity points where kinetic
+equation becomes inapplicable. In this case, at poles absence the solution
+reduces to non-damping Vlasov waves (oscillations). In the case of transverse
+waves, dispersion equation has two roots, corresponding to the branches of fast
+electromagnetic and slow electron waves. There is noted a possibility of
+experimental testing appearing exotic results with detecting frequencies and
+amplitudes of n-order overtones.",0711.1321v8
+2008-02-14,Influence of an inner disc on the orbital evolution of massive planets migrating in resonance,"The formation of resonant pairs of planets in exoplanetary systems involves
+planetary migration in the protoplanetary disc. After a resonant capture, the
+subsequent migration in this configuration leads to a large increase of
+planetary eccentricities if no damping mechanism is applied. This has led to
+the conclusion that the migration of resonant planetary systems cannot occur
+over large radial distances and has to be terminated sufficiently rapidly
+through disc dissipation.
+  In this study, we investigate whether the presence of an inner disc might
+supply an eccentricity damping of the inner planet, and if this effect could
+explain the observed eccentricities in some systems. To investigate the
+influence of an inner disc, we first compute hydrodynamic simulations of giant
+planets orbiting with a given eccentricity around an inner gas disc, and
+measure the effect of the latter on the planetary orbital parameters. We then
+perform detailed long term calculations of the GJ 876 system. We also run
+N-body simulations with artificial forces on the planets mimicking the effects
+of the inner and outer discs.
+  We find that the influence of the inner disc can not be neglected, and that
+it might be responsible for the observed eccentricities. In particular, we
+reproduce quite well the orbital parameters of a few systems engaged in 2:1
+mean motion resonances: GJ 876, HD 73526, HD 82943 and HD 128311. Finally, we
+derive analytically the effect that the inner disc should have on the inner
+planet to reach a specific orbital configuration with a given damping effect of
+the outer disc on the outer planet.",0802.2014v1
+2008-04-10,Embedded Oscillating Starless Cores,"In a previous paper we demonstrated that non-radial hydrodynamic oscillations
+of a thermally-supported (Bonnor-Ebert) sphere embedded in a low-density,
+high-temperature medium persist for many periods. The predicted column density
+variations and molecular spectral line profiles are similar to those observed
+in the Bok globule B68 suggesting that the motions in some starless cores may
+be oscillating perturbations on a thermally supported equilibrium structure.
+Such oscillations can produce molecular line maps which mimic rotation,
+collapse or expansion, and thus could make determining the dynamical state from
+such observations alone difficult.
+  However, while B68 is embedded in a very hot, low-density medium, many
+starless cores are not, having interior/exterior density contrasts closer to
+unity. In this paper we investigate the oscillation damping rate as a function
+of the exterior density. For concreteness we use the same interior model
+employed in Broderick et al. (2007), with varying models for the exterior gas.
+We also develop a simple analytical formalism, based upon the linear
+perturbation analysis of the oscillations, which predicts the contribution to
+the damping rates due to the excitation of sound waves in the external medium.
+We find that the damping rate of oscillations on globules in dense molecular
+environments is always many periods, corresponding to hundreds of thousands of
+years, and persisting over the inferred lifetimes of the globules.",0804.1790v1
+2008-05-07,Design of parametrically forced patterns and quasipatterns,"The Faraday wave experiment is a classic example of a system driven by
+parametric forcing, and it produces a wide range of complex patterns, including
+superlattice patterns and quasipatterns. Nonlinear three-wave interactions
+between driven and weakly damped modes play a key role in determining which
+patterns are favoured. We use this idea to design single and multi-frequency
+forcing functions that produce examples of superlattice patterns and
+quasipatterns in a new model PDE with parametric forcing. We make quantitative
+comparisons between the predicted patterns and the solutions of the PDE.
+Unexpectedly, the agreement is good only for parameter values very close to
+onset. The reason that the range of validity is limited is that the theory
+requires strong damping of all modes apart from the driven pattern-forming
+modes. This is in conflict with the requirement for weak damping if three-wave
+coupling is to influence pattern selection effectively. We distinguish the two
+different ways that three-wave interactions can be used to stabilise
+quasipatterns, and present examples of 12-, 14- and 20-fold approximate
+quasipatterns. We identify which computational domains provide the most
+accurate approximations to 12-fold quasipatterns, and systematically
+investigate the Fourier spectra of the most accurate approximations.",0805.0878v1
+2008-06-19,Itinerant spin excitations near the hidden order transition in URu2Si2,"By means of neutron scattering we show that the high-temperature precursor to
+the hidden order state of the heavy fermion superconductor URu$_{2}$Si$_{2}$
+exhibits heavily damped incommensurate paramagnons whose strong energy
+dispersion is very similar to that of the long-lived longitudinal f-spin
+excitations that appear below T$_{0}$. Since the underlying local f-exchange is
+preserved we expect only the f-d interactions to change across the phase
+transition and to cause the paramagnetic damping. The damping exhibits
+single-ion behavior independent of wave vector and vanishes below the hidden
+order transition. We suggest that this arises from a transition from valence
+fluctuations to a hybridized f-d state below T$_{0}$. Here we present evidence
+that the itinerant excitations, like those in chromium, are due to Fermi
+surface nesting of hole and electron pockets so that the hidden order phase
+likely originates from a Fermi-surface instability. We identify wave vectors
+that span nested regions of a band calculation and that match the neutron spin
+crossover from incommensurate to commensurate on approach to the hidden order
+phase.",0806.3137v2
+2008-11-21,Specific heat anomalies of open quantum systems,"The evaluation of the specific heat of an open, damped quantum system is a
+subtle issue. One possible route is based on the thermodynamic partition
+function which is the ratio of the partition functions of system plus bath and
+of the bath alone. For the free damped particle it has been shown, however,
+that the ensuing specific heat may become negative for appropriately chosen
+environments. Being an open system this quantity then naturally must be
+interpreted as the change of the specific heat obtained as the difference
+between the specific heat of the heat bath coupled to the system degrees of
+freedom and the specific heat of the bath alone. While this difference may
+become negative, the involved specific heats themselves are always positive;
+thus, the known thermodynamic stability criteria are perfectly guaranteed. For
+a damped quantum harmonic oscillator, instead of negative values, under
+appropriate conditions one can observe a dip in the difference of specific
+heats as a function of temperature. Stylized minimal models containing a single
+oscillator heat bath are employed to elucidate the occurrence of the anomalous
+temperature dependence of the corresponding specific heat values. Moreover, we
+comment on the consequences for the interpretation of the density of states
+based on the thermal partitionfunction.",0811.3509v2
+2008-11-26,Three-dimensional simulations of multiple protoplanets embedded in a protostellar disc,"Protoplanet eccentricities of e >~ H/r can slow or reverse migration, but
+previous 2D studies have shown that gravitational scattering cannot maintain
+significant planet eccentricities against disc-induced damping. We simulate the
+evolution of low-mass protoplanetary swarms in three dimensions. The aim is to
+examine both protoplanet survival rates and the dynamical structure of the
+resulting planetary systems, and to compare them with 2D simulations. We
+present results from a 3D hydrodynamic simulation of eight protoplanets
+embedded in a protoplanetary disc. We also present a suite of simulations
+performed using an N-body code, modified to include prescriptions for planetary
+migration and for eccentricity and inclination damping. These prescriptions
+were obtained by fitting analytic formulae to hydrodynamic simulations of
+planets embedded in discs with initially eccentric and/or inclined orbits. As
+was found in two dimensions, differential migration produces groups of
+protoplanets in stable, multiple mean-motion resonances that migrate in
+lockstep, preventing prolonged periods of gravitational scattering. In almost
+all simulations, this leads to large-scale migration of the protoplanet swarm
+into the central star in the absence of a viable stopping mechanism. The
+evolution involves mutual collisions, occasional instances of large-scale
+scattering, and the frequent formation of the long-lived, co-orbital planet
+systems that arise in > 30% of all runs. Disc-induced damping overwhelms
+eccentricity and inclination growth due to planet-planet interactions.
+Co-orbital planets are a natural outcome of dynamical relaxation in a strongly
+dissipative environment, and if observed in nature would imply that such a
+period of evolution commonly arises during planetary formation.",0811.4322v1
+2008-12-15,Swift-UVOT captures the earliest ultraviolet spectrum of a Gamma Ray Burst,"We present the earliest ever ultraviolet spectrum of a gamma-ray burst (GRB)
+as observed with the Swift-UVOT. The GRB 081203A spectrum was observed for 50
+seconds with the UV grism starting 251 seconds after the Swift-BAT trigger when
+the GRB was of u ~13.4 mag and still rising to its peak optical brightness. The
+UV grism spectrum shows a damped Ly-alpha line, Ly-beta, and the Lyman
+continuum break at a redshift z = 2.05 +/- 0.01. A model fit to the Lyman
+absorption implies log N(HI) = 22.0 +/- 0.2 cm-2, which is typical for GRB host
+galaxies with damped Ly-alpha absorbers. This observation of GRB 081203A
+demonstrates that for GRBs brighter than v ~14 mag and with 0.5 < z < 3.5 the
+UVOT will be able to provide redshifts, and probe for damped Ly-alpha absorbers
+within 4-6 minutes from the time of the Swift-BAT trigger.",0812.2943v2
+2008-12-16,On the oscillations of dissipative superfluid neutron stars,"We investigate the oscillations of slowly rotating superfluid stars, taking
+into account the vortex mediated mutual friction force that is expected to be
+the main damping mechanism in mature neutron star cores. Working to linear
+order in the rotation of the star, we consider both the fundamental f-modes and
+the inertial r-modes. In the case of the (polar) f-modes, we work out an
+analytic approximation of the mode which allows us to write down a closed
+expression for the mutual friction damping timescale. The analytic result is in
+good agreement with previous numerical results obtained using an energy
+integral argument. We extend previous work by considering the full range of
+permissible values for the vortex drag, e.g. the friction between each
+individual vortex and the electron fluid. This leads to the first ever results
+for the f-mode in the strong drag regime. Our estimates provide useful insight
+into the dependence on, and relevance of, various equation of state parameters.
+In the case of the (axial) r-modes, we confirm the existence of two classes of
+modes. However, we demonstrate that only one of these sets remains purely axial
+in more realistic neutron star models. Our analysis lays the foundation for
+companion studies of the mutual friction damping of the r-modes at second order
+in the slow-rotation approximation, the first time evolutions for superfluid
+neutron star perturbations and also the first detailed attempt at studying the
+dynamics of superfluid neutron stars with both a relative rotation between the
+components and mutual friction.",0812.3023v1
+2009-03-27,Cascade and Damping of Alfvén-Cyclotron Fluctuations: Application to Solar Wind Turbulence,"It is well-recognized that the presence of magnetic fields will lead to
+anisotropic energy cascade and dissipation of astrophysical turbulence. With
+the diffusion approximation and linear dissipation rates, we study the cascade
+and damping of Alfv\'en-cyclotron fluctuations in solar plasmas numerically.
+For an isotropic case the steady-state turbulence spectra are nearly isotropic
+in the inertial range and can be fitted by a single power-law function with a
+spectral index of -3/2, similar to the Iroshnikov-Kraichnan phenomenology.
+Beyond the MHD regime the kinetic effects make the spectrum softer at higher
+wavenumbers. In the dissipation range the turbulence spectrum cuts off at the
+wavenumber, where the damping rate becomes comparable to the cascade rate, and
+the cutoff wavenumber changes with the wave propagation direction. The angle
+averaged turbulence spectrum of the isotropic model resembles a broken
+power-law. Taking into account the Doppler effects, the model naturally
+reproduces the broken power-law turbulence spectra observed in the solar wind
+and predicts that a higher break frequency always comes along with a softer
+dissipation range spectrum that may be caused by the increase of the turbulence
+intensity, the reciprocal of the plasma \beta, and/or the angle between the
+solar wind velocity and the mean magnetic field. These predictions can be
+tested by detailed comparisons with more accurate observations.",0903.4904v1
+2009-04-29,Synthetic electric fields and phonon damping in carbon nanotubes and graphene,"Smoothly varying lattice strain in graphene affects the Dirac carriers
+through a synthetic gauge field. When the lattice strain is time dependent, as
+in connection with phononic excitations, the gauge field becomes time dependent
+and the synthetic vector potential is also associated with an electric field.
+We show that this synthetic electric field has observable consequences. Joule
+heating associated with the currents driven by the synthetic electric field
+dominates the intrinsic damping, caused by the electron-phonon interaction, of
+many acoustic phonon modes of graphene and metallic carbon nanotubes when
+including the effects of disorder and Coulomb interactions. Several important
+consequences follow from the observation that by time-reversal symmetry, the
+synthetic electric field associated with the vector potential has opposite
+signs for the two valleys. First, this implies that the synthetic electric
+field drives charge-neutral valley currents and is therefore unaffected by
+screening. This frequently makes the effects of the synthetic vector potential
+more relevant than a competing effect of the scalar deformation potential which
+has a much larger bare coupling constant. Second, valley currents decay by
+electron-electron scattering (valley Coulomb drag) which causes interesting
+temperature dependence of the damping rates. While our theory pertains first
+and foremost to metallic systems such as doped graphene and metallic carbon
+nanotubes, the underlying mechanisms should also be relevant for semiconducting
+carbon nanotubes when they are doped.",0904.4660v1
+2010-02-05,Implementation of an Innovative Bio Inspired GA and PSO Algorithm for Controller design considering Steam GT Dynamics,"The Application of Bio Inspired Algorithms to complicated Power System
+Stability Problems has recently attracted the researchers in the field of
+Artificial Intelligence. Low frequency oscillations after a disturbance in a
+Power system, if not sufficiently damped, can drive the system unstable. This
+paper provides a systematic procedure to damp the low frequency oscillations
+based on Bio Inspired Genetic (GA) and Particle Swarm Optimization (PSO)
+algorithms. The proposed controller design is based on formulating a System
+Damping ratio enhancement based Optimization criterion to compute the optimal
+controller parameters for better stability. The Novel and contrasting feature
+of this work is the mathematical modeling and simulation of the Synchronous
+generator model including the Steam Governor Turbine (GT) dynamics. To show the
+robustness of the proposed controller, Non linear Time domain simulations have
+been carried out under various system operating conditions. Also, a detailed
+Comparative study has been done to show the superiority of the Bio inspired
+algorithm based controllers over the Conventional Lead lag controller.",1002.1184v1
+2010-03-15,Small BGK waves and nonlinear Landau damping,"Consider 1D Vlasov-poisson system with a fixed ion background and periodic
+condition on the space variable. First, we show that for general homogeneous
+equilibria, within any small neighborhood in the Sobolev space W^{s,p}
+(p>1,s<1+(1/p)) of the steady distribution function, there exist nontrivial
+travelling wave solutions (BGK waves) with arbitrary minimal period and
+traveling speed. This implies that nonlinear Landau damping is not true in
+W^{s,p}(s<1+(1/p)) space for any homogeneous equilibria and any spatial period.
+Indeed, in W^{s,p} (s<1+(1/p)) neighborhood of any homogeneous state, the long
+time dynamics is very rich, including travelling BGK waves, unstable
+homogeneous states and their possible invariant manifolds. Second, it is shown
+that for homogeneous equilibria satisfying Penrose's linear stability
+condition, there exist no nontrivial travelling BGK waves and unstable
+homogeneous states in some W^{s,p} (p>1,s>1+(1/p)) neighborhood. Furthermore,
+when p=2,we prove that there exist no nontrivial invariant structures in the
+H^{s} (s>(3/2)) neighborhood of stable homogeneous states. These results
+suggest the long time dynamics in the W^{s,p} (s>1+(1/p)) and particularly, in
+the H^{s} (s>(3/2)) neighborhoods of a stable homogeneous state might be
+relatively simple. We also demonstrate that linear damping holds for initial
+perturbations in very rough spaces, for linearly stable homogeneous state. This
+suggests that the contrasting dynamics in W^{s,p} spaces with the critical
+power s=1+(1/p) is a trully nonlinear phenomena which can not be traced back to
+the linear level.",1003.3005v1
+2010-04-06,Electronic screening and damping in magnetars,"We calculate the screening of the ion-ion potential due to electrons in the
+presence of a large background magnetic field, at densities of relevance to
+neutron star crusts. Using the standard approach to incorporate electron
+screening through the one-loop polarization function, we show that the magnetic
+field produces important corrections both at short and long distances. In
+extreme fields, realized in highly magnetized neutron stars called magnetars,
+electrons occupy only the lowest Landau levels in the relatively low density
+region of the crust. Here our results show that the screening length for
+Coulomb interactions between ions can be smaller than the inter-ion spacing.
+More interestingly, we find that the screening is anisotropic and the screened
+potential between two static charges exhibits long range Friedel oscillations
+parallel to the magnetic field. This long-range oscillatory behavior is likely
+to affect the lattice structure of ions, and can possibly create rod-like
+structures in the magnetar crusts. We also calculate the imaginary part of the
+electron polarization function which determines the spectrum of electron-hole
+excitations and plays a role in damping lattice phonon excitations. We
+demonstrate that even for modest magnetic fields this damping is highly
+anisotropic and will likely lead to anisotropic phonon heat transport in the
+outer neutron star crust.",1004.0926v1
+2010-06-25,Decoherence window and electron-nuclear cross-relaxation in the molecular magnet V 15,"Rabi oscillations in the V_15 Single Molecule Magnet (SMM) embedded in the
+surfactant DODA have been studied at different microwave powers. An intense
+damping peak is observed when the Rabi frequency Omega_R falls in the vicinity
+of the Larmor frequency of protons w_N, while the damping time t_R of
+oscillations reaches values 10 times shorter than the phase coherence time t_2
+measured at the same temperature. The experiments are interpreted by the N-spin
+model showing that t_R is directly associated with the decoherence via
+electronic/nuclear spin cross-relaxation in the rotating reference frame. It is
+shown that this decoherence is accompanied with energy dissipation in the range
+of the Rabi frequencies w_N - sigma_e < Omega_R < w_N, where sigma_e is the
+mean super-hyperfine field (in frequency units) induced by protons at SMMs.
+Weaker damping without dissipation takes place outside this dissipation window.
+Simple local field estimations suggest that this rapid cross-relaxation in
+resonant microwave field observed for the first time in SMMV_15 should take
+place in other SMMs like Fe_8 and Mn_12 containing protons, too.",1006.4960v3
+2010-08-12,Dynamical damping terms for symmetry-seeking shift conditions,"Suitable gauge conditions are fundamental for stable and accurate
+numerical-relativity simulations of inspiralling compact binaries. A number of
+well-studied conditions have been developed over the last decade for both the
+lapse and the shift and these have been successfully used both in vacuum and
+non-vacuum spacetimes when simulating binaries with comparable masses. At the
+same time, recent evidence has emerged that the standard ""Gamma-driver"" shift
+condition requires a careful and non-trivial tuning of its parameters to ensure
+long-term stable evolutions of unequal-mass binaries. We present a novel gauge
+condition in which the damping constant is promoted to be a dynamical variable
+and the solution of an evolution equation. We show that this choice removes the
+need for special tuning and provides a shift damping term which is free of
+instabilities in our simulations and dynamically adapts to the individual
+positions and masses of the binary black-hole system. Our gauge condition also
+reduces the variations in the coordinate size of the apparent horizon of the
+larger black hole and could therefore be useful when simulating binaries with
+very small mass ratios.",1008.2212v2
+2010-08-31,A SINFONI Integral Field Spectroscopy Survey for Galaxy Counterparts to Damped Lyman-alpha Systems - II. Dynamical Properties of the Galaxies towards Q0302-223 and Q1009-0026,"Details of processes through which galaxies convert their gas into stars need
+to be studied in order to obtain a complete picture of galaxy formation. One
+way to tackle these phenomena is to relate the HI gas and the stars in
+galaxies. Here, we present dynamical properties of Damped and sub-Damped
+Lyman-alpha Systems identified in H-alpha emission with VLT/SINFONI at near
+infra-red wavelengths. While the DLA towards Q0302-223 is found to be
+dispersion-dominated, the sub-DLA towards Q1009-0026 shows clear signatures of
+rotation. We use a proxy to circular velocity to estimate the mass of the halo
+in which the sub-DLA resides and find M_halo=10^12.6 M_sun. We also derive
+dynamical masses of these objects, and find M_dyn=10^10.3 M_sun and 10^10.9
+M_sun. For one of the two systems (towards Q0302-223), we are able to derive a
+stellar mass of M_*=10^9.5 M_sun from Spectral Energy Distribution fit. The gas
+fraction in this object is 1/3rd, comparable to similar objects at these
+redshifts. Our work illustrates that detailed studies of quasar absorbers can
+offer entirely new insights into our knowledge of the interaction between stars
+and the interstellar gas in galaxies.",1009.0027v1
+2010-11-10,"Standing Slow-Mode Waves in Hot Coronal Loops: Observations, Modeling, and Coronal Seismology","Strongly damped Doppler shift oscillations are observed frequently associated
+with flarelike events in hot coronal loops. In this paper, a review of the
+observed properties and the theoretical modeling is presented. Statistical
+measurements of physical parameters (period, decay time, and amplitude) have
+been obtained based on a large number of events observed by SOHO/SUMER and
+Yohkoh/BCS. Several pieces of evidence are found to support their
+interpretation in terms of the fundamental standing longitudinal slow mode. The
+high excitation rate of these oscillations in small- or micro-flares suggest
+that the slow mode waves are a natural response of the coronal plasma to
+impulsive heating in closed magnetic structure. The strong damping and the
+rapid excitation of the observed waves are two major aspects of the waves that
+are poorly understood, and are the main subject of theoretical modeling. The
+slow waves are found mainly damped by thermal conduction and viscosity in hot
+coronal loops. The mode coupling seems to play an important role in rapid
+excitation of the standing slow mode. Several seismology applications such as
+determination of the magnetic field, temperature, and density in coronal loops
+are demonstrated. Further, some open issues are discussed.",1011.2483v1
+2010-12-01,Dissipative processes in superfluid neutron stars,"We present some results about a novel damping mechanism of r-mode
+oscillations in neutron stars due to processes that change the number of
+protons, neutrons and electrons. Deviations from equilibrium of the number
+densities of the various species lead to the appearance in the Euler equations
+of the system of a dissipative mechanism, the so-called rocket effect. The
+evolution of the r-mode oscillations of a rotating neutron star are influenced
+by the rocket effect and we present estimates of the corresponding damping
+timescales. In the description of the system we employ a two-fluid model, with
+one fluid consisting of all the charged components locked together by the
+electromagnetic interaction, while the second fluid consists of superfluid
+neutrons. Both components can oscillate however the rocket effect can only
+efficiently damp the countermoving r-mode oscillations, with the two fluids
+oscillating out of phase. In our analysis we include the mutual friction
+dissipative process between the neutron superfluid and the charged component.
+We neglect the interaction between the two r-mode oscillations as well as
+effects related with the crust of the star. Moreover, we use a simplified model
+of neutron star assuming a uniform mass distribution.",1012.0345v1
+2010-12-08,Nonequilibrium dynamics of the Holstein polaron driven by external electric field,"This work represents a fundamental study of a Holstein polaron in one
+dimension driven away from the ground state by a constant electric field.
+Taking fully into account quantum effects we follow the time-evolution of the
+system from its ground state as the constant electric field is switched on at t
+= 0, until it reaches a steady state. At weak electron phonon coupling (EP) the
+system experiences damped Bloch oscillations (BO) characteristic for
+noninteracting electron band. An analytic expression of the steady state
+current is proposed in terms of weak EP coupling and large electric field. For
+moderate values of EP coupling the oscillations are almost critically damped
+and the system reaches the steady state after a short time. In the strong
+coupling limit weakly damped BO, consistent with nearly adiabatic evolution
+within the polaron band, persist up to extremely large electric fields. A
+traveling polaron under the influence of the electric field leaves behind a
+trail of phonon excitations absorbing the excess energy gained from the
+electric field. The shape of the traveling polaron is investigated in details.",1012.1716v3
+2011-01-19,Numerical simulation of fundamental trapped sausage modes,"Context: We integrate the 2D MHD ideal equations of a straight slab to
+simulate observational results associated with fundamental sausage trapped
+modes. Aims: Starting from a non-equilibrium state with a dense chromospheric
+layer, we analyse the evolution of the internal plasma dynamics of magnetic
+loops, subject to line-tying boundary conditions, and with the coronal
+parameters described in Asai et al. (2001) and Melnikov et al. (2002) to
+investigate the onset and damping of sausage modes. Methods: To integrate the
+equations we used a high resolution shock-capturing (HRSC) method specially
+designed to deal appropriately with flow discontinuities. Results: Due to
+non-linearities and inhomogeneities, pure modes are difficult to sustain and
+always occur coupled among them so as to satisfy, e.g., the line-tying
+constraint. We found that, in one case, the resonant coupling of the sausage
+fundamental mode with a slow one results in a non-dissipative damping of the
+former. Conclusions: In scenarios of thick and dense loops, where the
+analytical theory predicts the existence of fundamental trapped sausage modes,
+the coupling of fast and slow quasi-periodic modes -with a node at the center
+of the longitudinal speed- occur contributing to the damping of the fast mode.
+If a discontinuity in the total pressure between the loop and the corona is
+assumed, a fundamental fast sausage transitory leaky regime is spontaneously
+produced and an external compressional Alfv\'en wave takes away the magnetic
+energy.",1101.3782v1
+2011-03-25,Dissipation and Vertical Energy Transport in Radiation-Dominated Accretion Disks,"Standard models of radiation supported accretion disks generally assume that
+diffusive radiation flux is solely responsible for vertical heat transport.
+This requires that heat must be generated at a critical rate per unit volume if
+the disk is to be in hydrostatic and thermal equilibrium. This raises the
+question of how heat is generated and how energy is transported in MHD
+turbulence. By analysis of a number of radiation/MHD stratified shearing-box
+simulations, we show that the divergence of the diffusive radiation flux is
+indeed capped at the critical rate, but deep inside the disk, substantial
+vertical energy flux is also carried by advection of radiation. Work done by
+radiation pressure is a significant part of the energy budget, and much of this
+work is dissipated later through damping by radiative diffusion. We show how
+this damping can be measured in the simulations, and identify its physical
+origins. Radiative damping accounts for as much as tens of percent of the total
+dissipation, and is the only realistic physical mechanism for dissipation of
+turbulence that can actually be resolved in numerical simulations of accretion
+disks. Buoyancy associated with dynamo-driven, highly magnetized,
+nearly-isobaric nonlinear slow magnetosonic fluctuations is responsible for the
+radiation advection flux, and also explains the persistent periodic magnetic
+upwelling seen at all values of the radiation to gas pressure ratio. The
+intimate connection between radiation advection and magnetic buoyancy is the
+first example we know of in astrophysics in which a dynamo has direct impact on
+the global energetics of a system.",1103.5052v1
+2011-06-09,Planet-disk interaction in highly inclined systems,"We study the interaction of a proto-planetary disk and a planet on a highly
+inclined orbit in the linear regime. The evolution of the planet is dominated
+by dynamical friction for planet masses above several Earth-masses. Smaller
+planets are dominated by aerodynamic drag, especially for very high
+inclinations and retrograde orbits.
+  The time-scales associated with migration and inclination damping are
+calculated. For certain values of the inclination, the inclination damping
+time-scale is longer than the migration time-scale and the disk lifetime. This
+result shows that highly inclined planets can not (re-)align with the
+proto-planetary disk.
+  We discuss the dependence of numerical simulations on the gravitational
+softening parameter. We find only a logarithmic dependence, making global three
+dimensional simulations of this process computationally feasible.
+  A large fraction of Hot Jupiters is on highly inclined orbits with respect to
+the rotation axis of the star. On the other hand small-mass planetary systems
+discovered by the Kepler mission have low mutual inclinations. This shows that
+there are two distinct formation mechanisms at work. The process that creates
+inclined Hot Jupiters does not operate on small mass planets because the
+damping timescales are so long that these systems would still be inclined
+today.",1106.1869v2
+2011-08-16,Brownian force noise from molecular collisions and the sensitivity of advanced gravitational wave observatories,"We present an analysis of Brownian force noise from residual gas damping of
+reference test masses as a fundamental sensitivity limit in small force
+experiments. The resulting acceleration noise increases significantly when the
+distance of the test mass to the surrounding experimental apparatus is smaller
+than the dimension of the test mass itself. For the Advanced LIGO
+interferometric gravitational wave observatory, where the relevant test mass is
+a suspended 340 mm diameter cylindrical end mirror, the force noise power is
+increased by roughly a factor 40 by the presence of a similarly shaped reaction
+mass at a nominal separation of 5 mm. The force noise, of order 20 fN\rthz\ for
+$2 \times 10^{-6}$ Pa of residual H$_2$ gas, rivals quantum optical
+fluctuations as the dominant noise source between 10 and 30 Hz. We present here
+a numerical and analytical analysis for the gas damping force noise for
+Advanced LIGO, backed up by experimental evidence from several recent
+measurements. Finally, we discuss the impact of residual gas damping on the
+gravitational wave sensitivity and possible mitigation strategies.",1108.3254v2
+2011-09-23,Accretion of Rocky Planets by Hot Jupiters,"The observed population of Hot Jupiters displays a stunning variety of
+physical properties, including a wide range of densities and core sizes for a
+given planetary mass. Motivated by the observational sample, this paper studies
+the accretion of rocky planets by Hot Jupiters, after the Jovian planets have
+finished their principal migration epoch and become parked in $\sim4$-day
+orbits. In this scenario, rocky planets form later and then migrate inward due
+to torques from the remaining circumstellar disk, which also damps the orbital
+eccentricity. This mechanism thus represents one possible channel for
+increasing the core masses and metallicities of Hot Jupiters. This paper
+determines probabilities for the possible end states for the rocky planet:
+collisions with the Jovian planets, accretion onto the star, ejection from the
+system, and long-term survival of both planets. These probabilities depend on
+the mass of the Jovian planet and its starting orbital eccentricity, as well as
+the eccentricity damping rate for the rocky planet. Since these systems are
+highly chaotic, a large ensemble ($N\sim10^3$) of simulations with effectively
+equivalent starting conditions is required. Planetary collisions are common
+when the eccentricity damping rate is sufficiently low, but are rare otherwise.
+For systems that experience planetary collisions, this work determines the
+distributions of impact velocities -- both speeds and impact parameters -- for
+the collisions. These velocity distributions help determine the consequences of
+the impacts, e.g., where energy and heavy elements are deposited within the
+giant planets.",1109.5104v1
+2011-09-27,Dispersion and damping of zone-boundary magnons in the noncentrosymmetric superconductor CePt3Si,"Inelastic neutron scattering (INS) is employed to study damped spin-wave
+excitations in the noncentrosymmetric heavy-fermion superconductor CePt3Si
+along the antiferromagnetic Brillouin-zone boundary in the low-temperature
+magnetically ordered state. Measurements along the (1/2 1/2 L) and (H H 1/2-H)
+reciprocal-space directions reveal deviations in the spin-wave dispersion from
+the previously reported model. Broad asymmetric shape of the peaks in energy
+signifies strong spin-wave damping by interactions with the particle-hole
+continuum. Their energy width exhibits no evident anomalies as a function of
+momentum along the (1/2 1/2 L) direction, which could be attributed to
+Fermi-surface nesting effects, implying the absence of pronounced commensurate
+nesting vectors at the magnetic zone boundary. In agreement with a previous
+study, we find no signatures of the superconducting transition in the magnetic
+excitation spectrum, such as a magnetic resonant mode or a superconducting spin
+gap, either at the magnetic ordering wavevector (0 0 1/2) or at the zone
+boundary. However, the low superconducting transition temperature in this
+material still leaves the possibility of such features being weak and therefore
+hidden below the incoherent background at energies ~0.1 meV, precluding their
+detection by INS.",1109.5784v1
+2011-11-06,The various manifestations of collisionless dissipation in wave propagation,"The propagation of an electrostatic wave packet inside a collisionless and
+initially Maxwellian plasma is always dissipative because of the irreversible
+acceleration of the electrons by the wave. Then, in the linear regime, the wave
+packet is Landau damped, so that in the reference frame moving at the group
+velocity, the wave amplitude decays exponentially with time. In the nonlinear
+regime, once phase mixing has occurred and when the electron motion is nearly
+adiabatic, the damping rate is strongly reduced compared to the Landau one, so
+that the wave amplitude remains nearly constant along the characteristics. Yet,
+we show here that the electrons are still globally accelerated by the wave
+packet, and, in one dimension, this leads to a non local amplitude dependence
+of the group velocity. As a result, a freely propagating wave packet would
+shrink, and, therefore, so would its total energy. In more than one dimension,
+not only does the magnitude of the group velocity nonlinearly vary, but also
+its direction. In the weakly nonlinear regime, when the collisionless damping
+rate is still significant compared to its linear value, this leads to an
+effective defocussing effect which we quantify, and which we compare to the
+self-focussing induced by wave front bowing.",1111.1391v2
+2011-11-15,Spin waves in nanosized magnetic films,"We have studied spin excitations in nanosized magnetic films in the
+Heisenberg model with magnetic dipole and exchange interactions by the spin
+operator diagram technique. Dispersion relations of spin waves in thin magnetic
+films (in two-dimensional magnetic monolayers and in two-layer magnetic films)
+and the spin-wave resonance spectrum in N-layer structures are found. For thick
+magnetic films generalized Landau-Lifshitz equations are derived from first
+principles. Landau-Lifshitz equations have the integral (pseudodifferential)
+form, but not differential one. Spin excitations are determined by simultaneous
+solution of the Landau-Lifshitz equations and the equation for the
+magnetostatic potential. For normal magnetized ferromagnetic films the spin
+wave damping has been calculated in the one-loop approximation for a diagram
+expansion of the Green functions at low temperature. In thick magnetic films
+the magnetic dipole interaction makes a major contribution to the relaxation of
+long-wavelength spin waves. Thin films have a region of low relaxation of
+long-wavelength spin waves. In thin magnetic films four-spin-wave processes
+take place and the exchange interaction makes a major contribution to the
+damping. It is found that the damping of spin waves propagating in magnetic
+monolayer is proportional to the quadratic dependence on the temperature and is
+very low for spin waves with small wavevectors. Spin-wave devices on the base
+of nanosized magnetic films are proposed -- tunable narrow-band spin-wave
+filters with high quality at the microwave frequency range and field-effect
+transistor (FET) structures contained nanosized magnetic films under the gate
+electrode. Spin-wave resonances in nanosized magnetic films can be used to
+construct FET structures operating in Gigahertz and Terahertz frequency bands.",1111.3532v1
+2011-12-16,Nonlinear viscous damping and gravitational wave detectability of the f-mode instability in neutron stars,"We study the damping of the gravitational radiation-driven f-mode instability
+in rotating neutron stars by nonlinear bulk viscosity in the so-called
+supra-thermal regime. In this regime the dissipative action of bulk viscosity
+is known to be enhanced as a result of nonlinear contributions with respect to
+the oscillation amplitude. Our analysis of the f-mode instability is based on a
+time-domain code that evolves linear perturbations of rapidly rotating
+polytropic neutron star models. The extracted mode frequency and eigenfunctions
+are subsequently used in standard energy integrals for the gravitational wave
+growth and viscous damping. We find that nonlinear bulk viscosity has a
+moderate impact on the size of the f-mode instability window, becoming an
+important factor and saturating the mode's growth at a relatively large
+oscillation amplitude. We show similarly that nonlinear bulk viscosity leads to
+a rather high saturation amplitude even for the r-mode instability. In
+addition, we show that the action of bulk viscosity can be significantly
+mitigated by the presence of superfluidity in neutron star matter. Apart from
+revising the f-mode's instability window we provide results on the mode's
+gravitational wave detectability. Considering an f-mode-unstable neutron star
+located in the Virgo cluster and assuming a mode amplitude at the level allowed
+by bulk viscosity, we find that the emitted gravitational wave signal could be
+detectable by advanced ground-based detectors such as Advanced LIGO/Virgo and
+the Einstein Telescope.",1112.3931v2
+2012-01-23,PageRank and rank-reversal dependence on the damping factor,"PageRank (PR) is an algorithm originally developed by Google to evaluate the
+importance of web pages. Considering how deeply rooted Google's PR algorithm is
+to gathering relevant information or to the success of modern businesses, the
+question of rank-stability and choice of the damping factor (a parameter in the
+algorithm) is clearly important. We investigate PR as a function of the damping
+factor d on a network obtained from a domain of the World Wide Web, finding
+that rank-reversal happens frequently over a broad range of PR (and of d). We
+use three different correlation measures, Pearson, Spearman, and Kendall, to
+study rank-reversal as d changes, and show that the correlation of PR vectors
+drops rapidly as d changes from its frequently cited value, $d_0=0.85$.
+Rank-reversal is also observed by measuring the Spearman and Kendall rank
+correlation, which evaluate relative ranks rather than absolute PR.
+Rank-reversal happens not only in directed networks containing rank-sinks but
+also in a single strongly connected component, which by definition does not
+contain any sinks. We relate rank-reversals to rank-pockets and bottlenecks in
+the directed network structure. For the network studied, the relative rank is
+more stable by our measures around $d=0.65$ than at $d=d_0$.",1201.4787v1
+2012-02-28,Planetesimal Dynamics in Inclined Binary Systems: The Role of Gas-Disk Gravity,"We investigate the effects of gas-disk gravity on the planetesimal dynamics
+in inclined binary systems, where the circumprimary disk plane is tilted by a
+significant angle ($i_B$) with respect to the binary disk plane. Our focus is
+on the Lidov-Kozai mechanism and the evolution of planetesimal eccentricity and
+inclination. Using both analytical and numerical methods, we find that, on one
+hand, the disk gravity generally narrows down the Kozai-on region, i.e., the
+Lidov-Kozai effect can be suppressed in certain parts of (or even the whole of)
+the disk, depending on various parameters. In the Kozai-off region,
+planetesimals would move on orbits close to the mid-plane of gas-disk, with the
+relative angle ($i^{'}$) following a small amplitude periodical oscillation. On
+the other hand, when we include the effects of disk gravity, we find that the
+Lidov-Kozai effect can operate even at arbitrarily low inclinations ($i_B$),
+although lower $i_B$ leads to a smaller Kozai-on region. Furthermore, in the
+Kozai-on region, most planetesimals' eccentricities can be excited to extremely
+high values ($\sim 1$), and such extreme high eccentricities usually accompany
+orbital flipping, i.e., planetesimal orbit flips back and forth between
+anterograde and retrograde. Once a planetesimal reaches very high orbital
+eccentricity, gas drag damping will shrink the planetesimal orbit, forming a
+""hot planetesimal"" on a near circular orbit very close to the primary star.
+Such a mechanism, if replacing the planetesimals and gas drag damping with
+Jupiters and tidal damping respectively, may lead to frequent production of
+hot-Jupiters.",1202.6102v1
+2012-04-20,The Stability of Massive Main Sequence Stars as a Function of Metallicity,"We investigate the pulsational stability of massive (M >~ 120 Msun) main
+sequence stars of a range of metallicities, including primordial, Population
+III stars. We include a formulation of convective damping motivated by
+numerical simulations of the interaction between convection and periodic shear
+flows. We find that convective viscosity is likely strong enough to stabilize
+radial pulsations whenever nuclear-burning (the epsilon-mechanism) is the
+dominant source of driving. This suggests that massive main sequence stars with
+Z <~ 2 x 10^-3 are pulsationally stable and are unlikely to experience
+pulsation-driven mass loss on the main sequence. These conclusions are,
+however, sensitive to the form of the convective viscosity and highlight the
+need for further high-resolution simulations of the convection-oscillation
+interaction. For more metal-rich stars (Z >~ 2 x 10^-3), the dominant
+pulsational driving arises due to the kappa-mechanism arising from the
+iron-bump in opacity and is strong enough to overcome convective damping. Our
+results highlight that even for oscillations with periods a few orders of
+magnitude shorter than the outer convective turnover time, the ""frozen-in""
+approximation for the convection-oscillation interaction is inappropriate, and
+convective damping should be taken into account when assessing mode stability.",1204.4741v1
+2012-05-14,Dynamics of multipartite quantum correlations under decoherence,"Quantum discord is an optimal resource for the quantification of classical
+and non-classical correlations as compared to other related measures. Geometric
+measure of quantum discord is another measure of quantum correlations.
+Recently, the geometric quantum discord for multipartite states has been
+introduced by Jianwei Xu [arxiv:quant/ph.1205.0330]. Motivated from the recent
+study [Ann. Phys. 327 (2012) 851] for the bipartite systems, I have
+investigated global quantum discord (QD) and geometric quantum discord (GQD)
+under the influence of external environments for different multipartite states.
+Werner-GHZ type three-qubit and six-qubit states are considered in inertial and
+non-inertial settings. The dynamics of QD and GQD is investigated under
+amplitude damping, phase damping, depolarizing and flipping channels. It is
+seen that the quantum discord vanishes for p>0.75 in case of three-qubit GHZ
+states and for p>0.5 for six qubit GHZ states. This implies that multipartite
+states are more fragile to decoherence for higher values of N. Surprisingly, a
+rapid sudden death of discord occurs in case of phase flip channel. However,
+for bit flip channel, no sudden death happens for the six-qubit states. On the
+other hand, depolarizing channel heavily influences the QD and GQD as compared
+to the amplitude damping channel. It means that the depolarizing channel has
+the most destructive influence on the discords for multipartite states. From
+the perspective of accelerated observers, it is seen that effect of environment
+on QD and GQD is much stronger than that of the acceleration of non-inertial
+frames. The degradation of QD and GQD happens due to Unruh effect. Furthermore,
+QD exhibits more robustness than GQD when the multipartite systems are exposed
+to environment.",1205.3133v1
+2012-06-04,In search of random uncorrelated particle motion (RUM) in a simple random flow field,"DNS studies of dispersed particle motion in isotropic homogeneous turbulence
+[1] have revealed the existence of a component of random uncorrelated motion
+(RUM)dependent on the particle inertia {\tau}p(normalised particle response
+time or Stoke number). This paper reports the presence of RUM in a simple
+linear random smoothly varying flow field of counter rotating vortices where
+the two-particle velocity correlation was measured as a function of spatial
+separation. Values of the correlation less than one for zero separation
+indicated the presence of RUM. In terms of Stokes number, the motion of the
+particles in one direction corresponds to either a heavily damped ({\tau}p <
+0.25) or lightly damped ({\tau}p > 0.25)harmonic oscillator. In the lightly
+damped case the particles overshoot the stagnation lines of the flow and are
+projected from one vortex to another (the so-called sling-shot effect). It is
+shown that RUM occurs only when {\tau}p > 0.25, increasing monotonically with
+increasing Stokes number. Calculations of the particle pair separation
+distribution function show that equilibrium of the particle concentration field
+is never reached, the concentration at zero separation increasing monotonically
+with time. This is consistent with the calculated negative values of the
+average Liapounov exponent (finite compressibility) of the particle velocity
+field.",1206.0572v1
+2012-06-11,Solitons in a parametrically driven damped discrete nonlinear Schrödinger equation,"We consider a parametrically driven damped discrete nonlinear Schr\""odinger
+(PDDNLS) equation. Analytical and numerical calculations are performed to
+determine the existence and stability of fundamental discrete bright solitons.
+We show that there are two types of onsite discrete soliton, namely onsite type
+I and II. We also show that there are four types of intersite discrete soliton,
+called intersite type I, II, III, and IV, where the last two types are
+essentially the same, due to symmetry. Onsite and intersite type I solitons,
+which can be unstable in the case of no dissipation, are found to be stabilized
+by the damping, whereas the other types are always unstable. Our further
+analysis demonstrates that saddle-node and pitchfork (symmetry-breaking)
+bifurcations can occur. More interestingly, the onsite type I, intersite type
+I, and intersite type III-IV admit Hopf bifurcations from which emerge periodic
+solitons (limit cycles). The continuation of the limit cycles as well as the
+stability of the periodic solitons are computed through the numerical
+continuation software Matcont. We observe subcritical Hopf bifurcations along
+the existence curve of the onsite type I and intersite type III-IV. Along the
+existence curve of the intersite type I we observe both supercritical and
+subcritical Hopf bifurcations.",1206.2405v1
+2012-07-13,Axion as a cold dark matter candidate: low-mass case,"Axion as a coherently oscillating scalar field is known to behave as a cold
+dark matter in all cosmologically relevant scales. For conventional axion mass
+with 10^{-5} eV, the axion reveals a characteristic damping behavior in the
+evolution of density perturbations on scales smaller than the solar system
+size. The damping scale is inversely proportional to the square-root of the
+axion mass. We show that the axion mass smaller than 10^{-24} eV induces a
+significant damping in the baryonic density power spectrum in cosmologically
+relevant scales, thus deviating from the cold dark matter in the scale smaller
+than the axion Jeans scale. With such a small mass, however, our basic
+assumption about the coherently oscillating scalar field is broken in the early
+universe. This problem is shared by other dark matter models based on the
+Bose-Einstein condensate and the ultra-light scalar field. We introduce a
+simple model to avoid this problem by introducing evolving axion mass in the
+early universe, and present observational effects of present-day low-mass axion
+on the baryon density power spectrum, the cosmic microwave background radiation
+(CMB) temperature power spectrum, and the growth rate of baryon density
+perturbation. In our low-mass axion model we have a characteristic small-scale
+cutoff in the baryon density power spectrum below the axion Jeans scale. The
+small-scale deviations from the cold dark matter model in both matter and CMB
+power spectra clearly differ from the ones expected in the cold dark matter
+model mixed with the massive neutrinos as a hot dark matter component.",1207.3124v1
+2012-09-04,Solving Vlasov Equations Using NRxx Method,"In this paper, we propose a moment method to numerically solve the Vlasov
+equations using the framework of the NRxx method developed in [6, 8, 7] for the
+Boltzmann equation. Due to the same convection term of the Boltzmann equation
+and the Vlasov equation, it is very convenient to use the moment expansion in
+the NRxx method to approximate the distribution function in the Vlasov
+equations. The moment closure recently presented in [5] is applied to achieve
+the globally hyperbolicity so that the local well-posedness of the moment
+system is attained. This makes our simulations using high order moment
+expansion accessible in the case of the distribution far away from the
+equilibrium which appears very often in the solution of the Vlasov equations.
+With the moment expansion of the distribution function, the acceleration in the
+velocity space results in an ordinary differential system of the macroscopic
+velocity, thus is easy to be handled. The numerical method we developed can
+keep both the mass and the momentum conserved. We carry out the simulations of
+both the Vlasov-Poisson equations and the Vlasov-Poisson-BGK equations to study
+the linear Landau damping. The numerical convergence is exhibited in terms of
+the moment number and the spatial grid size, respectively. The variation of
+discretized energy as well as the dependence of the recurrence time on moment
+order is investigated. The linear Landau damping is well captured for different
+wave numbers and collision frequencies. We find that the Landau damping rate
+linearly and monotonically converges in the spatial grid size. The results are
+in perfect agreement with the theoretic data in the collisionless case.",1209.0527v1
+2012-10-09,A close-pair analysis of damp mergers at intermediate redshifts,"We have studied the kinematics of ~2800 candidate close pair galaxies at
+0.1<z<1.2 identified from the Canada-France-Hawaii Telescope Legacy Survey
+fields. Spectra of these systems were obtained using spectrometers on the 6.5m
+Magellan and 5m Hale telescopes. These data allow us to constrain the rate of
+dry mergers at intermediate redshifts and to test the `hot halo' model for
+quenching of star formation. Using virial radii estimated from the correlation
+between dynamical and stellar masses published by Leauthaud et al. (2011), we
+find that around 1/5 of our candidate pairs are likely to share a common dark
+matter halo (our metric for close physical association). These pairs are
+divided into red-red, blue-red and blue-blue systems using the rest-frame
+colors classification method introduced in Chou et al. (2011). Galaxies
+classified as red in our sample have very low star-formation rates, but they
+need not be totally quiescent, and hence we refer to them as `damp', rather
+than `dry', systems. After correcting for known selection effects, the fraction
+of blue-blue pairs is significantly greater than that of red-red and blue-red
+pairs. Red-red pairs are almost entirely absent from our sample, suggesting
+that damp mergers are rare at z~0.5. Our data supports models with a short
+merging timescale (<0.5 Gyr) in which star-formation is enhanced in the early
+phase of mergers, but quenched in the late phase. Hot halo models may explain
+this behaviour, but only if virial shocks that heat gas are inefficient until
+major mergers are nearly complete.",1210.2692v1
+2012-10-24,Dual Trigger of Transverse Oscillations in a Prominence by EUV Fast and Slow Coronal Waves: SDO/AIA and STEREO/EUVI Observations,"We analyze flare-associated transverse oscillations in a quiescent solar
+prominence on 8-9 September, 2010. Both the flaring active region and the
+prominence were located near the West limb, with a favorable configuration and
+viewing angle. The fulldisk extreme ultraviolet (EUV) images of the Sun
+obtained with high spatial and temporal resolution by the Atmospheric Imaging
+Assembly (AIA) aboard the Solar Dynamics Observatory, show flare-associated
+lateral oscillations of the prominence sheet. The STEREO-A spacecraft, 81.5
+degrees ahead of the Sun-Earth line, provides on-disk view of the
+flare-associated coronal disturbances. We derive the temporal profile of the
+lateral displacement of the prominence sheet by using the image
+cross-correlation technique. The displacement curve was de-trended and the
+residual oscillatory pattern was derived. We fit these oscillations with a
+damped cosine function with a variable period and find that the period is
+increasing. The initial oscillation period (P0) is 28.2 minutes and the damping
+time (t_D) of 44 minutes. We confirm the presence of fast and slow EUV wave
+components. Using STEREO-A observations we derive a propagation speed of 250
+km/s for the slow EUV wave by applying time-slice technique to the running
+difference images. We propose that the prominence oscillations are excited by
+the fast EUV wave while the increase in oscillation period of the prominence is
+an apparent effect, related to a phase change due to the slow EUV wave acting
+as a secondary trigger. We discuss implications of the dual trigger effect for
+coronal prominence seismology and scaling law studies of damping mechanisms.",1210.6690v1
+2012-11-07,Gaussification through decoherence,"We investigate the loss of nonclassicality and non-Gaussianity of a
+single-mode state of the radiation field in contact with a thermal reservoir.
+The damped density matrix for a Fock-diagonal input is written using the Weyl
+expansion of the density operator. Analysis of the evolution of the
+quasiprobability densities reveals the existence of two successive
+characteristic times of the reservoir which are sufficient to assure the
+positivity of the Wigner function and, respectively, of the $P$ representation.
+We examine the time evolution of non-Gaussianity using three recently
+introduced distance-type measures. They are based on the Hilbert-Schmidt
+metric, the relative entropy, and the Bures metric. Specifically, for an
+$M$-photon-added thermal state, we obtain a compact analytic formula of the
+time-dependent density matrix that is used to evaluate and compare the three
+non-Gaussianity measures. We find a good consistency of these measures on the
+sets of damped states. The explicit damped quasiprobability densities are shown
+to support our general findings regarding the loss of negativities of Wigner
+and $P$ functions during decoherence. Finally, we point out that Gaussification
+of the attenuated field mode is accompanied by a nonmonotonic evolution of the
+von Neumann entropy of its state conditioned by the initial value of the mean
+photon number.",1211.1701v3
+2012-11-14,New algorithm for footstep localization using seismic sensors in an indoor environment,"In this study, we consider the use of seismic sensors for footstep
+localization in indoor environments. A popular strategy of localization is to
+use the measured differences in arrival times of source signals at multiple
+pairs of receivers. In the literature, most algorithms that are based on time
+differences of arrival (TDOA) assume that the propagation velocity is a
+constant as a function of the source position, which is valid for air
+propagation or even for narrow band signals. However a bounded medium such as a
+concrete slab (encountered in indoor environement) is usually dispersive and
+damped. In this study, we demonstrate that under such conditions, the concrete
+slab can be assimilated to a thin plate; considering a Kelvin-Voigt damping
+model, we introduce the notion of {\em perceived propagation velocity}, which
+decreases when the source-sensor distance increases. This peculiar behaviour
+precludes any possibility to rely on existing localization methods in indoor
+environment. Therefore, a new localization algorithm that is adapted to a
+damped and dispersive medium is proposed, using only on the sign of the
+measured TDOA (SO-TDOA). A simulation and some experimental results are
+included, to define the performance of this SO-TDOA algorithm.",1211.3233v2
+2013-02-05,Complex fragment emission in low energy light-ion reactions,"Inclusive energy spectra of the complex fragments (3 $\leq$ Z $\leq$ 5)
+emitted in the reactions $^{12}$C (77 MeV)+ $^{28}$Si, $^{11}$B (64 MeV)+
+$^{28}$Si and $^{12}$C (73 MeV)+ $^{27}$Al (all having the same excitation
+energy of $ \sim$ 67 MeV), have been measured in the angular range of
+10$^\circ$ $\lesssim \theta_{lab} \lesssim$ 60$^\circ$. The fully energy damped
+(fusion-fission) and the partially energy damped (deep inelastic) components of
+the fragment energy spectra have been extracted. It has been found that the
+yields of the fully energy damped fragments for all the above reactions are in
+conformity with the respective statistical model predictions. The time scales
+of various deep inelastic fragment emissions have been extracted from the
+angular distribution data. The angular momentum dissipation in deep inelastic
+collisions has been estimated from the data and it has been found to be close
+to the corresponding sticking limit value.",1302.1002v1
+2013-02-11,Propagation of Alfvénic Waves From Corona to Chromosphere and Consequences for Solar Flares,"How do magnetohydrodynamic waves travel from the fully ionized corona, into
+and through the underlying partially ionized chromosphere, and what are the
+consequences for solar flares? To address these questions, we have developed a
+2-fluid model (of plasma and neutrals) and used it to perform 1D simulations of
+Alfv\'en waves in a solar atmosphere with realistic density and temperature
+structure. Studies of a range of solar features (faculae, plage, penumbra and
+umbra) show that energy transmission from corona to chromosphere can exceed 20%
+of incident energy for wave periods of one second or less. Damping of waves in
+the chromosphere depends strongly on wave frequency: waves with periods 10
+seconds or longer pass through the chromosphere with relatively little damping,
+however, for periods of 1 second or less, a substantial fraction (37%-100%) of
+wave energy entering the chromosphere is damped by ion-neutral friction in the
+mid and upper chromosphere, with electron resistivity playing some role in the
+lower chromosphere and in umbras. We therefore conclude that Alfv\'enic waves
+with periods of a few seconds or less are capable of heating the chromosphere
+during solar flares, and speculate that they could also contribute to electron
+acceleration or exciting sunquakes.",1302.2458v1
+2013-02-25,Non-classical Correlations in the Quantum Search Algorithm,"Entanglement lies at the heart of quantum mechanics and has no classical
+analogue. It is central to the speed up achieved by quantum algorithms over
+their classical counterparts. The Grover's search algorithm is one such
+algorithm which enables us to achieve a quadratic speed up over any known
+classical algorithm that searches for an element in an unstructured database.
+Here, we analyse and quantify the effects of entanglement in the generalized
+version of this algorithm for two qubits. By 'generalized', it is meant that
+the use of any arbitrary single qubit unitary gate is permitted to create
+superposed states. Our analysis has been firstly on a noise free environment
+and secondly in the presence of noise. In the absence of noise, we establish a
+relation between the concurrence and the amplitude of the final state thereby
+showing the explicit effects of entanglement on the same. Moreover, the effects
+of noisy channels, namely amplitude and phase damping channels are studied. We
+investigate the amount of quantum correlation in the states obtained after the
+phase inversion stage of the algorithm followed by interaction of those states
+with the noisy environment. The quantum correlations are quantified by
+geometric discord. It has been revealed that the states generated after the
+effect of amplitude damping on the phase inverted states of the quantum search
+algorithm possess non-zero quantum correlation even when entanglement is
+absent. However, this is absent in the phase damping scenario.",1302.6005v1
+2013-03-01,Generation of Electrostatic Waves via Parametric Instability and Heating of Solar Corona,"In the upper layers of the solar atmosphere the temperature increases
+sharply. We studied possibility of the transfer of neutrals motion energy into
+the electrostatic waves.Electrostatic waves could damp in the upper layers of
+the solar atmosphere and their energy could be transformed into the thermal
+energy of the solar atmosphere plasma. When studying the plasma dynamics in the
+low altitudes of the solar atmosphere, we investigated hydrodynamics of the
+plasma which consists of thee components-electrons, ions and neutrals. In order
+to study evolution of disturbances of high amplitudes the parametric resonance
+technique is used. The dispersion relation for the electrostatic waves excited
+due tot he motion of neutrals is derived. The frequencies of electromagnetic
+waves which could be excited due to existence of the acoustic wave are found.
+The increment of excited electrostatic waves are determined. The motion of the
+neutrals in the lower solar atmosphere, where ionization rate is low, could
+excite electrostatic waves. In the upper solar atmosphere the ionization rate
+increases and motion of the neutrals could not support electrostatic waves and
+these waves could damp due to the collision of the charged particles. The
+energy of the damping waves could be transformed into the thermal energy of the
+plasma in the upper atmosphere.",1303.0151v1
+2013-03-19,Cosmic Ray Streaming in Clusters of Galaxies,"The observed bimodality in radio luminosity in galaxy clusters is puzzling.
+We investigate the possibility that cosmic-ray (CR) streaming in the
+intra-cluster medium can 'switch off' hadronically induced radio and gamma-ray
+emission. For self-confined CRs, this depends on the source of MHD wave
+damping: if only non-linear Landau damping operates, then CRs stream on the
+slow Alfvenic timescale, but if turbulent wave damping operates, super-Alfvenic
+streaming is possible. As turbulence increases, it promotes outward streaming
+more than it enables inward turbulent advection. Curiously, the CR flux is
+independent of $\nabla f$ (as long as it is non-zero) and depends only on
+plasma parameters; this enables radio halos with flat inferred CR profiles to
+turn off. We perform 1D time-dependent calculations of a radio mini-halo
+(Perseus) and giant radio halo (Coma) and find that both diminish in radio
+luminosity by an order of magnitude in several hundred Myr, given plausible
+estimates for the magnetic field in the outskirts of the cluster. Due to the
+energy dependence of CR streaming, spectral curvature develops, and radio halos
+turn off more slowly at low frequencies -- properties consistent with
+observations. Similarly, CR streaming rapidly turns off gamma-ray emission at
+the high-energies probed by Cherenkov telescopes, but not at the low energies
+probed by Fermi. CR mediated wave-heating of the ICM is unaffected, as it is
+dominated by ~GeV CRs which stream Alfvenically.",1303.4746v1
+2013-05-13,New features of ion acoustic waves in inhomogeneous and permeating plasmas,"It is generally accepted that the ion acoustic (IA) wave in plasmas
+containing ions and electrons with the same temperature is of minor importance
+due to strong damping of the wave by hot resonant ions. In this work it will be
+shown that the IA wave is susceptible to excitation even in plasmas with hot
+ions when both an electromagnetic transverse wave and a background density
+gradient are present in the plasma, and in addition the wave is in fact
+unstable (i.e., growing) in the case of permeating homogeneous plasmas. The
+multi-component fluid theory is used to describe the IA wave susceptibility for
+excitation in inhomogeneous plasmas and its coupling with electromagnetic
+waves. The growing IA wave in permeating homogeneous plasmas is described by
+the kinetic theory. In plasmas with density and temperature gradients the IA
+wave is effectively coupled with the electromagnetic waves. In comparison to
+ordinary IA wave in homogeneous plasma, the Landau damping of the present wave
+is much smaller, and to demonstrate this effect a simple but accurate fluid
+model is presented for the Landau damping. In the case of permeating plasmas, a
+kinetic mechanism for the current-less IA wave instability is presented, with a
+very low threshold for excitation as compared with ordinary
+electron-current-driven kinetic instability. Such growing IA waves can
+effectively heat plasma in the upper solar atmosphere by a stochastic heating
+mechanism presented in the work. The results of this work suggest that the IA
+wave role in the heating of the solar atmosphere (chromosphere and corona)
+should be reexamined.",1305.2739v1
+2013-07-19,Exact 3D solution for static and damped harmonic response of simply supported general laminates,"The state-space method is adapted to obtain three dimensional exact solutions
+for the static and damped dynamic behaviors of simply supported general
+laminates. The state-space method is written in a general form that permits to
+handle both cross-ply and antisymmetric angle-ply laminates. This general form
+also permits to obtain exact solutions for general laminates, albeit with some
+constraints. For the general case and for the static behavior, either an
+additive term is added to the load to simulate simply supported boundary
+conditions, or the plate bends in a particular way. For the dynamic behavior,
+the general case leads to pairs of natural frequencies for each order, with
+associated mode shapes. Finite element simulations have been performed to
+validate most of the results presented in this study. As the boundary
+conditions needed for the general case are not so straightforward, a specific
+discussion has been added. It is shown that these boundary conditions also work
+for the two aforementioned laminate classes. The damped harmonic response of a
+non symmetrical isotropic sandwich is studied for different frequencies around
+the fundamental frequency. The static and undamped dynamic behaviors of the
+[-15/15], [0/30/0] and [-10/0/40] laminates are studied for various
+length-to-thickness ratios.",1307.5285v2
+2013-07-25,Lyman-alpha Heating of Inhomogeneous High-redshift Intergalactic Medium,"The intergalactic medium (IGM) prior to the epoch of reionization consists
+mostly of neutral hydrogen gas. Ly-alpha photons produced by early stars
+resonantly scatter off hydrogen atoms, causing energy exchange between the
+radiation field and the gas. This interaction results in moderate heating of
+the gas due to the recoil of the atoms upon scattering, which is of great
+interest for future studies of the pre-reionization IGM in the HI 21 cm line.
+We investigate the effect of this Ly-alpha heating in the IGM with linear
+density, temperature, and velocity perturbations. Perturbations smaller than
+the diffusion length of photons could be damped due to heat conduction by
+Ly-alpha photons. The scale at which damping occurs and the strength of this
+effect depend on various properties of the gas, the flux of Ly-alpha photons
+and the way in which photon frequencies are redistributed upon scattering. To
+find the relevant length scale and the extent to which Ly-alpha heating affects
+perturbations, we calculate the gas heating rates by numerically solving
+linearized Boltzmann equations in which scattering is treated by the
+Fokker-Planck approximation. We find that (1) perturbations add a small
+correction to the gas heating rate, and (2) the damping of temperature
+perturbations occurs at scales with comoving wavenumber k>10^4 Mpc^{-1}, which
+are much smaller than the Jeans scale and thus unlikely to substantially affect
+the observed 21 cm signal.",1307.6859v2
+2013-11-12,Investigation into electron cloud effects in the International Linear Collider positron damping ring,"We report modeling results for electron cloud buildup and instability in the
+International Linear Collider positron damping ring. Updated optics, wiggler
+magnets, and vacuum chamber designs have recently been developed for the 5 GeV,
+3.2-km racetrack layout. An analysis of the synchrotron radiation profile
+around the ring has been performed, including the effects of diffuse and
+specular photon scattering on the interior surfaces of the vacuum chamber. The
+results provide input to the cloud buildup simulations for the various magnetic
+field regions of the ring. The modeled cloud densities thus obtained are used
+in the instability threshold calculations. We conclude that the mitigation
+techniques employed in this model will suffice to allow operation of the
+damping ring at the design operational specifications.",1311.2890v4
+2013-12-18,The behavior of transverse waves in nonuniform solar flux tubes. II. Implications for coronal loop seismology,"Seismology of coronal loops using observations of damped transverse
+oscillations in combination with results from theoretical models is a tool to
+indirectly infer physical parameters in the solar atmospheric plasma. Existing
+seismology schemes based on approximations to the period and damping time of
+kink oscillations are often used beyond their theoretical range of
+applicability. These approximations assume that the variation of density across
+the loop is confined to a nonuniform layer much thinner than the radius of the
+loop, but the results of the inversion problem often do not satisfy this
+preliminary hypothesis. Here, we determine the accuracy of the analytic
+approximations to the period and damping time, and its impact on seismology
+estimates, when largely nonuniform loops are considered. We find that the
+accuracy of the approximations when used beyond their range of applicability is
+strongly affected by the form of the density profile across the loop, that is
+observationally unknown and so must be arbitrarily imposed as part of the
+theoretical model. The error associated with the analytic approximations can be
+larger than 50% even for relatively thin nonuniform layers. This error directly
+affects the accuracy of approximate seismology estimates compared to actual
+numerical inversions. In addition, assuming different density profiles can
+produce noncoincident intervals of the seismic variables in inversions of the
+same event. The ignorance about the true shape of density variation across the
+loop is an important source of error that may dispute the reliability of
+parameters seismically inferred assuming an ad hoc density profile.",1312.5079v1
+2014-01-02,Quasi-Normal Modes for Subtracted Rotating and Magnetised Geometries,"We obtain explicit separable solutions of the wave equation of massless
+minimally coupled scalar fields in the subtracted geometry of four-dimensional
+rotating and Melvin (magnetised) four-charge black holes of the STU model, a
+consistent truncation of maximally supersymmetric supergravity with four types
+of electromagnetic fields. These backgrounds possess a hidden SL(2,R) x SL(2,R)
+x SO(3) symmetry and faithfully model the near horizon geometry of these black
+holes, but locate them in a confining asymptotically conical box. For each
+subtracted geometry we obtain two branches of quasi-normal modes, given in
+terms of hypergeometric functions and spherical harmonics. One branch is
+over-damped and the other under-damped and they exhibit rotational splitting.
+No black hole bomb is possible because the Killing field which co-rotates with
+the horizon is everywhere timelike outside the black hole. A five-dimensional
+lift of these geometries is given locally by the product of a BTZ black hole
+with a two-sphere. This allows an explicit analysis of the minimally coupled
+massive five-dimensional scalar field. Again, there are two branches, both
+damped, however now their oscillatory parts are shifted by the quantised wave
+number $k$ along the fifth circle direction.",1401.0544v3
+2014-03-12,Enhancing robustness of multiparty quantum correlations using weak measurement,"Multipartite quantum correlations are important resources for the development
+of quantum information and computation protocols. However, the resourcefulness
+of multipartite quantum correlations in practical settings is limited by its
+fragility under decoherence due to environmental interactions. Though there
+exist protocols to protect bipartite entanglement under decoherence, the
+implementation of such protocols for multipartite quantum correlations has not
+been sufficiently explored. Here, we study the effect of local amplitude
+damping channel on the generalized Greenberger-Horne-Zeilinger state, and use a
+protocol of optimal reversal quantum weak measurement to protect the
+multipartite quantum correlations. We observe that the weak measurement
+reversal protocol enhances the robustness of multipartite quantum correlations.
+Further it increases the critical damping value that corresponds to
+entanglement sudden death. To emphasize the efficacy of the technique in
+protection of multipartite quantum correlation, we investigate two proximately
+related quantum communication tasks, namely, quantum teleportation in a one
+sender, many receivers setting and multiparty quantum information splitting,
+through a local amplitude damping channel. We observe an increase in the
+average fidelity of both the quantum communication tasks under the weak
+measurement reversal protocol. The method may prove beneficial, for combating
+external interactions, in other quantum information tasks using multipartite
+resources.",1403.2939v1
+2014-04-11,Functional Regression for Quasar Spectra,"The Lyman-alpha forest is a portion of the observed light spectrum of distant
+galactic nuclei which allows us to probe remote regions of the Universe that
+are otherwise inaccessible. The observed Lyman-alpha forest of a quasar light
+spectrum can be modeled as a noisy realization of a smooth curve that is
+affected by a `damping effect' which occurs whenever the light emitted by the
+quasar travels through regions of the Universe with higher matter
+concentration. To decode the information conveyed by the Lyman-alpha forest
+about the matter distribution, we must be able to separate the smooth
+`continuum' from the noise and the contribution of the damping effect in the
+quasar light spectra. To predict the continuum in the Lyman-alpha forest, we
+use a nonparametric functional regression model in which both the response and
+the predictor variable (the smooth part of the damping-free portion of the
+spectrum) are function-valued random variables. We demonstrate that the
+proposed method accurately predicts the unobservable continuum in the
+Lyman-alpha forest both on simulated spectra and real spectra. Also, we
+introduce distribution-free prediction bands for the nonparametric functional
+regression model that have finite sample guarantees. These prediction bands,
+together with bootstrap-based confidence bands for the projection of the mean
+continuum on a fixed number of principal components, allow us to assess the
+degree of uncertainty in the model predictions.",1404.3168v1
+2014-06-04,Constraints on the gas masses of low-z damped Lyman-$α$ systems,"We report a deep search for redshifted HI 21 cm emission from three damped
+and sub-damped Lyman-$\alpha$ absorbers (DLAs) at $z \approx 0.1$ with the
+Green Bank Telescope (GBT). No evidence for a redshifted HI 21 cm emission
+signal was obtained in the GBT spectra of two absorbers, with the data on the
+third rendered unusable by terrestrial interference. The non-detections of HI
+21 cm emission yield strong constraints on the HI masses of the associated
+galaxies, M$_{\rm HI} < 2.3 \times 10^9 \times (\Delta V/100)^{1/2}$ M$_\odot$
+for the sub-DLA at $z = 0.0830$ towards J1553+3548, and M$_{\rm HI} < 2.7
+\times 10^9 \times (\Delta V/100)^{1/2}$ M$_\odot$ for the DLA at $z = 0.0963$
+towards J1619+3342, where $\Delta V$ is the HI 21 cm line width, in km
+s$^{-1}$. This continues the trend of low HI masses found in all low-$z$ DLAs
+and sub-DLAs that have been searched for redshifted HI 21 cm emission.
+Low-redshift absorbers with relatively low HI column densities, $\lesssim few
+\times 10^{20}$ cm$^{-2}$, thus do not typically arise in massive gas-rich
+galaxies.",1406.0991v2
+2014-06-09,Evolution of eccentricity and orbital inclination of migrating planets in 2:1 mean motion resonance,"We determine, analytically and numerically, the conditions needed for a
+system of two migrating planets trapped in a 2:1 mean motion resonance to enter
+an inclination-type resonance. We provide an expression for the asymptotic
+equilibrium value that the eccentricity $e_{\rm i}$ of the inner planet reaches
+under the combined effects of migration and eccentricity damping. We also show
+that, for a ratio $q$ of inner to outer masses below unity, $e_{\rm i}$ has to
+pass through a value $e_{\rm i,res}$ of order 0.3 for the system to enter an
+inclination-type resonance. Numerically, we confirm that such a resonance may
+also be excited at another, larger, value $e_{\rm i, res} \simeq 0.6$, as found
+by previous authors. A necessary condition for onset of an inclination-type
+resonance is that the asymptotic equilibrium value of $e_{\rm i}$ is larger
+than $e_{\rm i,res}$. We find that, for $q \le 1$, the system cannot enter an
+inclination-type resonance if the ratio of eccentricity to semimajor axis
+damping timescales $t_e/t_a$ is smaller than 0.2. This result still holds if
+only the eccentricity of the outer planet is damped and $q \lesssim 1$. As the
+disc/planet interaction is characterized by $t_e/t_a \sim 10^{-2}$, we conclude
+that excitation of inclination through the type of resonance described here is
+very unlikely to happen in a system of two planets migrating in a disc.",1406.2189v1
+2014-08-08,Stable Magnetic Droplet Solitons in Spin Transfer Nanocontacts,"Magnetic thin films with perpendicular magnetic anisotropy (PMA) have
+localized excitations that correspond to reversed dynamically precessing
+magnetic moments, known as magnetic droplet solitons. Fundamentally, these
+excitations are associated with an attractive interaction between elementary
+spin-excitations (i.e., magnons) and were predicted to occur in PMA materials
+in the absence of damping [1,2]. While damping, present in all magnetic
+materials, suppresses these excitations, it is now possible to compensate
+damping by spin transfer torques through electrical current flow in nanometer
+scale contacts to ferromagnetic thin films [3,4]. A theory predicts the
+appearance of magnetic droplet solitons at a threshold current in nanocontacts
+[5] and, recently, experimental signatures of droplet nucleation have been
+reported [6]. However, thus far, they have been observed to be nearly
+reversible excitations, with only partially reversed magnetization and to be
+subject to instabilities that cause them to drift away from the nanocontacts
+(i.e., drift instabilities) [6]. Here we show that magnetic droplet solitons
+can be stabilized in a spin transfer nanocontact. Further, they exhibit a
+strong hysteretic response to fields and currents and a nearly fully reversed
+magnetization in the contact. These observations, in addition to their
+fundamental interest, open up new applications for magnetic droplet solitons as
+multi-state high frequency current and field tunable oscillators.",1408.1902v1
+2014-08-19,Probing Electron Interactions in a Two-Dimensional System by Quantum Magneto-Oscillations,"We have experimentally studied the renormalized effective mass m* and Dingle
+temperature T_D in two spin subbands with essentially different electron
+populations. Firstly, we found that the product (m*T_D) that determines damping
+of quantum oscillations, to the first approximation, is the same in the
+majority and minority subbands even at the spin polarization degree as high as
+66\%. This result confirms the theoretical predictions that the interaction
+takes place at high energies ~ E_F rather than within a narrow strip of
+energies E_F\pm k_BT. Secondly, to the next approximation, we revealed a
+difference in the damping factor of the two spin subbands, which causes
+skewness of the oscillation lineshape. In the absence of the in-plane magnetic
+field, the damping factor (m*T_D) is systematically smaller in the
+spin-majority subband. The difference, quantified with the skew factor \gamma =
+(T_{D\downarrow}-T_{D\uparrow})/2T_{D0} can be as large as 20%. The skew factor
+tends to decrease as B_\parallel or temperature grow, or perpendicular field
+decreases; for low electron densities and high in-plane fields the skew factor
+even changes sign. Finally, we compared the temperature and magnetic field
+dependencies of the magneto-oscillations amplitude with predictions of the
+interaction correction theory, and found, besides some qualitative
+similarities, several quantitative and qualitative differences. To explain
+qualitatively our results, we suggested an empirical model that assumes the
+existence of easily magnetized triplet scatterers on the Si/SiO_2 interface.",1408.4393v1
+2014-08-20,Josephson junction ratchet: effects of finite capacitances,"We study transport in an asymmetric SQUID which is composed of a loop with
+three capacitively and resistively shunted Josephson junctions: two in series
+in one arm and the remaining one in the other arm. The loop is threaded by an
+external magnetic flux and the system is subjected to both a time-periodic and
+a constant current. We formulate the deterministic and, as well, the stochastic
+dynamics of the SQUID in terms of the Stewart-McCumber model and derive an
+equation for the phase difference across one arm, in which an effective
+periodic potential is of the ratchet type, i.e. its reflection symmetry is
+broken. In doing so, we extend and generalize earlier study by Zapata et al.
+[Phys. Rev. Lett. 77, 2292 (1996)] and analyze directed transport in wide
+parameter regimes: covering the over-damped to moderate damping regime up to
+its fully under-damped regime. As a result we detect the intriguing features of
+a negative (differential) conductance, repeated voltage reversals, noise
+induced voltage reversals and solely thermal noise-induced ratchet currents. We
+identify a set of parameters for which the ratchet effect is most pronounced
+and show how the direction of transport can be controlled by tailoring the
+external magnetic flux.",1408.4607v1
+2014-09-30,Collective modes in two- and three-dimensional electron systems with Rashba spin-orbit coupling,"In addition to charge plasmons, a 2D electron system with Rashba-type
+spin-orbit coupling (SOC) also supports three collective modes in the spin
+sector: the chiral-spin modes. We study the dispersions of the charge and spin
+modes and their coupling to each other within a generalized Random Phase
+Approximation for arbitrarily strong SOC, and both in 2D and 3D systems. In
+both 2D and 3D, we find that the charge plasmons are coupled to only one of the
+three chiral-spin modes. This coupling is shown to affect the dispersions of
+the modes at finite but not at zero wavenumbers. In 3D, the chiral-spin modes
+are strongly damped by particle-hole excitations and disappear for weak
+electron-electron interaction. Landau damping of the chiral-spin modes in 3D is
+directly related to the fact that, in contrast to 2D, there is no gap for
+particle-hole excitations between spin-split subbands. The gapless continuum is
+also responsible for Landau damping of the charge plasmon in 3D - a
+qualitatively new feature of the SOC system. We also discuss the optical
+conductivity of clean 2D and 3D systems and show that SOC introduces spectral
+weight at finite frequency in a such way that the sum rule is satisfied. The
+in-plane tranverse chiral-spin mode shows up as dispersing peak in the optical
+conductivity at finite number which can can be measured in the presence of
+diffraction grating. We also discuss possible experimental manifestations of
+chiral-spin modes in semiconductor quantum wells such InGaAs/AlGaAs and 3D
+giant Rashba materials of the BiTeI family.",1409.8666v1
+2014-11-15,Spin-transfer-torque through antiferromagnetic IrMn,"Spin-transfer-torque, a transfer of angular momentum between the electron
+spin and the local magnetic moments, is a promising and key mechanism to
+control ferromagnetic materials in modern spintronic devices . However, much
+less attention has been paid to the same effect in antiferromagnets. For the
+sake of investigating how the spin current interacts with the magnetic moments
+in antiferromagnets, we perform spin-torque ferromagnetic resonance
+measurements on Co20Fe60B20 4nm/Ir25Mn75 tIrMn nm/Pt 4 nm multilayers under a
+spin Hall effect of Pt. The effective magnetic damping in Co20Fe60B20 is
+modified by the spin current injected from the Pt layer via the IrMn layer. The
+results indicate that the spin current interacts with IrMn magnetic moments and
+exerts the anti-damping torque on the magnetic moments of Co20Fe60B20 through
+the IrMn. It is also found that the reduction of the exchange bias in the
+IrMn/Pt interface degrades the anti-damping torque exerted on the Co20Fe60B20
+layer, suggesting the transmission of the spin torque becomes less efficient as
+the interface exchange coupling degrades. Our work infers that the magnetic
+moments in IrMn can be manipulated by spin torque similarly to the one in a
+ferromagnetic layer.",1411.4100v4
+2014-11-28,On damped second-order gradient systems,"Using small deformations of the total energy, as introduced in [31], we
+establish that damped second order gradient systems
+$$u^{\prime\prime}(t)+\gamma u^\prime(t)+\nabla G(u(t))=0,$$may be viewed as
+quasi-gradient systems. In order to study the asymptotic behavior of these
+systems, we prove that any (nontrivial) desingularizing function appearing in
+KL inequality satisfies $\varphi(s)\ge c\sqrt s$ whenever the original function
+is definable and $C^2.$ Variants to this result are given. These facts are used
+in turn to prove that a desingularizing function of the potential $G$ also
+desingularizes the total energy and its deformed versions. Our approach brings
+forward several results interesting for their own sake: we provide an
+asymptotic alternative for quasi-gradient systems, either a trajectory
+converges, or its norm tends to infinity. The convergence rates are also
+analyzed by an original method based on a one-dimensional worst-case gradient
+system.We conclude by establishing the convergence of solutions of damped
+second order systems in various cases including the definable case. The
+real-analytic case is recovered and some results concerning convex functions
+are also derived.",1411.8005v5
+2015-01-12,Standing Slow MHD Waves in Radiatively Cooling Coronal Loops,"The standing slow magneto-acoustic oscillations in cooling coronal loops are
+investigated. There are two damping mechanisms which are considered to generate
+the standing acoustic modes in coronal magnetic loops namely thermal conduction
+and radiation. The background temperature is assumed to change temporally due
+to optically thin radiation. In particular, the background plasma is assumed to
+be radiatively cooling. The effects of cooling on longitudinal slow MHD modes
+is analytically evaluated by choosing a simple form of radiative function that
+ensures the temperature evolution of the background plasma due to radiation
+coincides with the observed cooling profile of coronal loops. The assumption of
+low-beta plasma leads to neglect the magnetic field perturbation and eventually
+reduces the MHD equations to a 1D system modelling longitudinal MHD
+oscillations in a cooling coronal loop. The cooling is assumed to occur on a
+characteristic time scale much larger than the oscillation period that
+subsequently enables using the WKB theory to study the properties of standing
+wave. The governing equation describing the time-dependent amplitude of waves
+is obtained and solved analytically. The analytically derived solutions are
+numerically evaluated to give further insight into the evolution of the
+standing acoustic waves. We find that the plasma cooling gives rise to a
+decrease in the amplitude of oscillations. In spite of the reduction in damping
+rate caused by rising the cooling, the damping scenario of slow standing MHD
+waves strongly increases in hot coronal loops.",1501.02689v1
+2015-01-12,Beta decay of 252Cf on the way to scission from the exit point,"Upon increasing significantly the nuclear elongation, the beta-decay energy
+grows. This paper investigates within a simple yet partly microscopic approach,
+the transition rate of the beta decay of the 252Cf nucleus on the way to
+scission from the exit point for a spontaneous fission process. A rather crude
+classical approximation is made for the corresponding damped collective motion
+assumed to be one dimensional. Given these assumptions, we only aim in this
+paper at providing the order of magnitudes of such a phenomenon. At each
+deformation the energy available for beta decay, is determined from such a
+dynamical treatment. Then, for a given elongation, transition rates for the
+allowed (Fermi) beta decay are calculated from pair correlated wave functions
+obtained within a macroscopic-microscopic approach and then integrated over the
+time corresponding to the whole descent from exit to scission. The results are
+presented as a function of the damping factor (inverse of the characteristic
+damping time) in use in our classical dynamical approach. For instance, in the
+case of a descent time from the exit to the scission points of about $10^{-
+20}$ second, one finds a total rate of beta decay corresponding roughly to 20
+events per year and per milligram of 252Cf. The inclusion of pairing
+correlations does not affect much these results.",1501.02701v1
+2015-01-13,Fundamental oscillation modes of neutron stars: validity of universal relations,"We study the $f$-mode frequencies and damping times of nonrotating neutron
+stars (NS) in general relativity (GR) by solving the linearized perturbation
+equations, with the aim to establish ""universal"" relations that depend only
+weakly on the equations of state (EOS). Using a more comprehensive set of EOSs,
+we re-examine some proposed linearizations that describe the $f$-mode
+parameters in terms of mass and radius of the neutron star (NS), and we test a
+more recent proposal for expressing the $f$-mode parameters as quadratic
+functions of the effective compactness. Our extensive results for each equation
+of state considered allow us to study the accuracy of each proposal. In
+particular, we find that the damping time deviates quite considerably from the
+proposed linearization. We introduce a new universal relation for the product
+of the $f$-mode frequency and damping time as a function of the (ordinary)
+compactness, which proved to be more accurate. The relations using the
+effective compactness on the other hand also fit our data accurately. Our
+results show that the maximum oscillation frequency depends strongly on the
+EOS, such that the measurement of a high oscillation frequency would rule out
+several EOSs. Lastly, we compare the exact mode frequencies to those obtained
+in the Cowling approximation, and also to results obtained with a nonlinear
+evolution code, validating the implementations of the different approaches.",1501.02970v2
+2015-02-13,Magnetohydrodynamic kink waves in nonuniform solar flux tubes: phase mixing and energy cascade to small scales,"Magnetohydrodynamic (MHD) kink waves are ubiquitously observed in the solar
+atmosphere. The propagation and damping of these waves may play relevant roles
+for the transport and dissipation of energy in the solar atmospheric medium.
+However, in the atmospheric plasma dissipation of transverse MHD wave energy by
+viscosity or resistivity needs very small spatial scales to be efficient. Here,
+we theoretically investigate the generation of small scales in nonuniform solar
+magnetic flux tubes due to phase mixing of MHD kink waves. We go beyond the
+usual approach based on the existence of a global quasi-mode that is damped in
+time due to resonant absorption. Instead, we use a modal expansion to express
+the MHD kink wave as a superposition of Alfv\'en continuum modes that are phase
+mixed as time evolves. The comparison of the two techniques evidences that the
+modal analysis is more physically transparent and describes both the damping of
+global kink motions and the building up of small scales due to phase mixing. In
+addition, we discuss that the processes of resonant absorption and phase mixing
+are intimately linked. They represent two aspects of the same underlying
+physical mechanism: the energy cascade from large scales to small scales due to
+naturally occurring plasma and/or magnetic field inhomogeneities. This process
+may provide the necessary scenario for efficient dissipation of transverse MHD
+wave energy in the solar atmospheric plasma.",1502.03949v1
+2015-03-25,Wave Propagation at Oblique Shocks: How Did Tycho Get Its Stripes?,"We describe a new model for the ""stripes"" of synchrotron radiation seen in
+the remnant of Tycho's supernova. In our picture, cosmic rays streaming ahead
+of the forward shock generate parallel (with respect to the local magnetic
+field direction) circularly polarized Alfven waves that are almost free of
+dissipation, and due to being circularly polarized exhibit no spatial variation
+of magnetic field strength. Following interaction with the SNR shock with
+nonzero obliquity, these parallel waves become obliquely propagating, due the
+the wave refraction (different in principle for the different plane wave
+components), and dissipation sets in. The magnetosonic polarization decays
+faster, due to transit time damping, leaving only the Alfven mode. This
+surviving mode now exhibits a spatial variation of the magnetic field, leading
+to local maxima and minima in the synchrotron emission, i.e. the stripes. We
+attribute the initial wave generation to the Bell instability, which in
+contrast to the resonant generation of upstream Alfven waves, gives rise to a
+preferred wavelength, and hence the single wave period at which the stripes are
+seen. Based on estimates for damping rates due to turbulent cascade and transit
+time damping, we estimate the dependence of the visibility of the stripes on
+the shock obliquity, and determine a maximum cosmic ray energy in Tycho's SNR
+in the range $6\times 10^{14} - 1\times 10^{15}$ eV.",1503.07497v1
+2015-03-30,Superradiance and instability of small rotating charged AdS black holes in all dimensions,"Rotating small AdS black holes exhibit the superradiant instability to
+low-frequency scalar perturbations, which is amenable to a complete analytic
+description in four dimensions. In this paper, we extend this description to
+all higher dimensions, focusing on slowly rotating charged AdS black holes with
+a single angular momentum. We divide the spacetime of these black holes into
+the near-horizon and far regions and find solutions to the scalar wave equation
+in each of these regions. Next, we perform the matching of these solutions in
+the overlap between the regions, by employing the idea that the orbital quantum
+number $ \ell $ can be thought of as an approximate integer. Thus, we obtain
+the complete low-frequency solution that allows us to calculate the complex
+frequency spectrum of quasinormal modes, whose imaginary part is determined by
+a small damping parameter. Finally, we find a remarkably instructive expression
+for the damping parameter, which appears to be a complex quantity in general.
+We show that the real part of the damping parameter can be used to give a {\it
+universal} analytic description of the superradiant instability for slowly
+rotating charged AdS black holes in all spacetime dimensions.",1503.08607v2
+2015-04-12,Evolution of Kinetic and Magnetic Energy in Intra Cluster Media,"Intra Cluster Media (ICMs) located at galaxy clusters is in the state of hot,
+tenuous, magnetized, and highly ionized X-ray emitting plasmas. This overall
+collisionless, viscous, and conductive magnetohydrodynamic (MHD) turbulence in
+ICM is simulated using hyper and physical magnetic diffusivity. The results
+show that fluctuating random plasma motion amplifies the magnetic field, which
+cascades toward the diffusivity scale passing through the viscous scale. The
+kinetic eddies in the subviscous scale are driven and constrained by the
+magnetic tension which finally gets balanced with the highly damping effect of
+the kinetic eddies. However, the saturated kinetic energy spectrum is deeper
+than that of the incompressible or compressible hydrodynamics fluid. To explain
+this unusual field profile we set up two simultaneous differential equations
+for the kinetic and magnetic energy spectrum using an Eddy Damped Quasi Normal
+Markovianized (EDQNM) approximation. The analytic solution tells us that the
+magnetic energy in addition to the viscous damping effect constrains the plasma
+motion leading to the power spectra: kinetic energy spectrum $E_V^k\sim k^{-3}$
+and corresponding representative magnetic energy spectrum $E_M^k\sim k^{-1/2}$.
+Also the comparison of simulation results with different resolutions and
+magnetic diffusivities implies the role of small scale magnetic energy in
+dynamo.",1504.02940v3
+2015-05-19,The elusive HI-> H2 transition in high-z damped Lyman-alpha systems,"We study the H2 molecular content in high redshift damped Lyman-alpha systems
+(DLAs) as a function of the HI column density. We find a significant increase
+of the H2 molecular content around log N(HI) (cm^-2)~21.5-22, a regime unprobed
+until now in intervening DLAs, beyond which the majority of systems have log
+N(H2) > 17. This is in contrast with lines of sight towards nearby stars, where
+such H2 column densities are always detected as soon as log N(HI)>20.7. This
+can qualitatively be explained by the lower average metallicity and possibly
+higher surrounding UV radiation in DLAs. However, unlike in the Milky Way, the
+overall molecular fractions remain modest, showing that even at a large N(HI)
+only a small fraction of overall HI is actually associated with the
+self-shielded H2 gas. Damped Lyman-alpha systems with very high-N(HI) probably
+arise along quasar lines of sight passing closer to the centre of the host
+galaxy where the gas pressure is higher. We show that the colour changes
+induced on the background quasar by continuum (dust) and line absorption (HI
+Lyman and H2 Lyman & Werner bands) in DLAs with log N(HI)~22 and metallicity
+~1/10 solar is significant, but not responsible for the long-discussed lack of
+such systems in optically selected samples. Instead, these systems are likely
+to be found towards intrinsically fainter quasars that dominate the quasar
+luminosity function. Colour biasing should in turn be severe at higher
+metallicities.",1505.04997v1
+2015-06-11,Dynamics near the subcritical transition of the 3D Couette flow I: Below threshold case,"We study small disturbances to the periodic, plane Couette flow in the 3D
+incompressible Navier-Stokes equations at high Reynolds number $\textbf{Re}$.
+We prove that for sufficiently regular initial data of size $\epsilon \leq
+c_0\textbf{Re}^{-1}$ for some universal $c_0 > 0$, the solution is global,
+remains within $O(c_0)$ of the Couette flow in $L^2$, and returns to the
+Couette flow as $t \rightarrow \infty$. For times $t \gtrsim
+\textbf{Re}^{1/3}$, the streamwise dependence is damped by a mixing-enhanced
+dissipation effect and the solution is rapidly attracted to the class of ""2.5
+dimensional"" streamwise-independent solutions referred to as streaks. Our
+analysis contains perturbations that experience a transient growth of kinetic
+energy from $O(\textbf{Re}^{-1})$ to $O(c_0)$ due to the algebraic linear
+instability known as the lift-up effect. Furthermore, solutions can exhibit a
+direct cascade of energy to small scales. The behavior is very different from
+the 2D Couette flow, in which stability is independent of $\textbf{Re}$,
+enstrophy experiences a direct cascade, and inviscid damping is dominant
+(resulting in a kind of inverse energy cascade). In 3D, inviscid damping will
+play a role on one component of the velocity, but the primary stability
+mechanism is the mixing-enhanced dissipation. Central to the proof is a
+detailed analysis of the interplay between the stabilizing effects of the
+mixing and enhanced dissipation and the destabilizing effects of the lift-up
+effect, vortex stretching, and weakly nonlinear instabilities connected to the
+non-normal nature of the linearization.",1506.03720v1
+2015-06-12,Casimir Friction Between Polarizable Particle and Half-Space with Radiation Damping and Image Damping at Zero Temperature,"Casimir friction between a polarizable particle and a semi-infinite space is
+a delicate physical phenomenon, as it concerns the interaction between a
+microscopic quantum particle and a semi-infinite reservoir. Not unexpectedly,
+results obtained in the past about the friction force obtained via different
+routes are sometimes, at least apparently, wildly different from each other.
+  Recently, we considered the Casimir friction force for two dielectric
+semi-infinite plates moving parallel to each other [J. S. H{\o}ye and I.
+Brevik, Eur. Phys. J. D {\bf 68}, 61 (2014)], and managed to get essential
+agreement with results obtained by Pendry (1997), Volokitin and Persson (2007),
+and Barton (2011). Our method was based upon use of the Kubo formalism. In the
+present paper we focus on the interaction between a polarizable particle and a
+dielectric half-space again, and calculate the friction force using the same
+basic method as before. The new ingredient in the present analysis is that we
+take into account radiative damping, and derive the modifications thereof. Some
+comparisons are also made with works from others. Essential agreement with the
+results of Intravaia, Behunin, and Dalvit can also be achieved using the
+modification of the atomic polarizability by the metallic plate.",1506.03937v2
+2015-07-08,Periods and damping rates of fast sausage oscillations in multi-shelled coronal loops,"Standing sausage modes are important in interpreting quasi-periodic
+pulsations in the lightcurves of solar flares. Their periods and damping times
+play an important role in seismologically diagnosing key parameters like the
+magnetic field strength in regions where flare energy is released. Usually such
+applications are based on theoretical results neglecting unresolved fine
+structures in magnetized loops. However, the existence of fine structuring is
+suggested on both theoretical and observational grounds. Adopting the framework
+of cold magnetohydrodynamics (MHD), we model coronal loops as magnetized
+cylinders with a transverse equilibrium density profile comprising a monolithic
+part and a modulation due to fine structuring in the form of concentric shells.
+The equation governing the transverse velocity perturbation is solved with an
+initial-value-problem approach, and the effects of fine structuring on the
+periods $P$ and damping times $\tau$ of global, leaky, standing sausage modes
+are examined. A parameter study shows that fine structuring, be it periodically
+or randomly distributed, brings changes of only a few percent to $P$ and $\tau$
+when there are more than about ten shells. The monolithic part, its steepness
+in particular, plays a far more important role in determining $P$ and $\tau$.
+We conclude that when measured values of $P$ and $\tau$ of sausage modes are
+used for seismological purposes, it is justified to use theoretical results
+where the effects due to fine structuring are neglected.",1507.02169v1
+2015-06-23,Resonant absorption of kink magnetohydrodynamic waves by a magnetic twist in coronal loops,"There is ample evidence of twisted magnetic structures in the solar corona.
+This motivates us to consider the magnetic twist as the cause of Alfven
+frequency continuum in the coronal loops, which can support the resonant
+absorption as a rapid damping mechanism for the observed coronal kink
+magnetohydrodynamic (MHD) oscillations. We model a coronal loop with a straight
+cylindrical magnetic flux tube which has constant but different densities in
+the interior and exterior regions. The magnetic field is assumed to be constant
+and aligned with the cylinder axis everywhere except a thin layer near the
+boundary of the flux tube which has an additional small magnetic field twist.
+Then, we investigate a number of possible instabilities that may arise in our
+model. In the thin tube thin boundary approximation, we derive the dispersion
+relation and solve it analytically to obtain the frequencies and damping rates
+of the fundamental (l=1) and first/second overtone (l=2,3) kink (m=1) MHD
+modes. We conclude that the resonant absorption by the magnetic twist can
+justify the rapid damping of kink MHD waves observed in coronal loops.
+Furthermore, the magnetic twist in the inhomogeneous layer can cause deviations
+from P1/P2=2 and P1/P3=3 which are comparable with the observations.",1507.02653v4
+2015-07-23,Asteroseismology of rapidly rotating neutron stars - an alternative approach,"In the present paper we examine gravitational wave asteroseismology relations
+for f-modes of rapidly rotating neutron stars. An approach different to the
+previous studies is employed - first, the moment of inertia is used instead of
+the stellar radius, and second, the normalization of the oscillation
+frequencies and damping times is different. It was shown that in the
+non-rotating case this can lead to a much stronger equation of state
+independence and our goal is to generalize the static relations to the rapidly
+rotating case and values of the spherical mode number $l\ge2$. We employ
+realistic equations of state that cover a very large range of stiffness in
+order to check better the universality of the relations. At the end we explore
+the inverse problem, i.e. obtain the neutron star parameters from the observed
+gravitational frequencies and damping times. It turns out that with this new
+set of relations we can solve the inverse problem with a very good accuracy
+using three frequencies that was not possible in the previous studies where one
+needs also the damping times. The asteroseismology relations are also
+particularly good for the massive rapidly rotating models that are subject to
+secular instabilities.",1507.06606v1
+2015-07-31,Eccentricity Evolution Through Accretion of Protoplanets,"Most of super-Earths detected by the radial velocity (RV) method have
+significantly smaller eccentricities than the eccentricities corresponding to
+velocity dispersion equal to their surface escape velocity (""escape
+eccentricities""). If orbital instability followed by giant impacts among
+protoplanets that have migrated from outer region is considered, it is usually
+considered that eccentricities of the merged bodies become comparable to those
+of orbital crossing bodies, which are excited up to their escape eccentricities
+by close scattering. However, the eccentricity evolution in the {\it in situ}
+accretion model has not been studied in detail. Here, we investigate the
+eccentricity evolution through {\it N}-body simulations. We have found that the
+merged planets tend to have much smaller eccentricities than the escape
+eccentricities due to very efficient collision damping. If the protoplanet
+orbits are initially well separated and their eccentricities are securely
+increased, an inner protoplanet collides at its apocenter with an outer
+protoplanet at its pericenter. The eccentricity of the merged body is the
+smallest for such configuration. Orbital inclinations are also damped by this
+mechanism and planets tend to share a same orbital plane, which is consistent
+with {\it Kepler} data. Such efficient collision damping is not found when we
+start calculations from densely packed orbits of the protoplanets. If the
+protoplanets are initially in the mean-motion resonances, which corresponds to
+well separated orbits, the {\it in situ} accretion model well reproduces the
+features of eccentricities and inclinations of multiple super-Earths/Earth
+systems discovered by RV and {\it Kepler} surveys.",1507.08809v1
+2015-08-25,Effects of inertia on the steady-shear rheology of disordered solids,"We study the finite-shear-rate rheology of disordered solids by means of
+molecular dynamics simulations in two dimensions. By systematically varying the
+damping magnitude $\zeta$ in the low-temperature limit, we identify two well
+defined flow regimes, separated by a thin (temperature-dependent) crossover
+region. In the overdamped regime, the athermal rheology is governed by the
+competition between elastic forces and viscous forces, whose ratio gives the
+Weissenberg number $Wi= \zeta \dot\gamma$ (up to elastic parameters); the
+macroscopic stress $\Sigma$ follows the frequently encountered Herschel-Bulkley
+law $\Sigma= \Sigma\_0 + k \sqrt{Wi}$, with yield stress
+$\Sigma\_0\textgreater{}0$. In the underdamped (inertial) regime, dramatic
+changes in the rheology are observed for low damping: the flow curve becomes
+non-monotonic. This change is not caused by longer-lived correlations in the
+particle dynamics at lower damping; instead, for weak dissipation, the sample
+heats up considerably due to, and in proportion to, the driving. By suitably
+thermostatting more or less underdamped systems, we show that their rheology
+only depends on their kinetic temperature and the shear rate, rescaled with
+Einstein's vibration frequency.",1508.06067v3
+2015-09-01,Persistence of a Non-Equilibrium State: Observation of a Boltzmannian Special Case,"Well before the atomistic nature of matter was experimentally established,
+Ludwig Boltzmann's audacious effort to explain the macroscopic world of human
+experience in terms of the workings of an unseen microscopic world met with
+vigorous opposition. A contentious point was the problem of irreversibility:
+the microscopic equations of motion are reversible, yet friction and viscosity
+cause things always to slow down and warm up, never to speed up and cool down.
+What was worse, Boltzmann himself discovered that his transport equation
+predicts special cases in which gases never come to thermal equilibrium, a
+particular example being that the monopole ""breathe"" mode of gas will never
+damp if it is confined in 3D to a perfectly isotropic harmonic potential. Such
+absences of damping were not observed in nature. Nondamping of a monopole mode
+in lower dimensional systems has only very recently been observed, using cold
+atoms. Kinoshita et al. and Chevy et al. have experimentally observed
+suppressed relaxation in highly elongated geometries. The difficulty in
+generating sufficiently spherical harmonic confinement for ultracold atoms,
+however, has meant that Boltzmann's fully 3D, isotropic case has never been
+observed. With the development of a new magnetic trap capable of producing
+near-spherical harmonic confinement for ultracold atoms, we have been able to
+make the first observation of this historically significant oddity. We observe
+a monopole mode for which the collisional contribution to damping vanishes, a
+long-delayed vindication for Boltzmann's microscopic theory.",1509.00366v1
+2015-09-07,Spectral inequality and resolvent estimate for the bi-Laplace operator,"On a compact Riemannian manifold with boundary, we prove a spectral
+inequality for the bi-Laplace operator in the case of so-called ""clamped""
+boundary conditions , that is, homogeneous Dirichlet and Neumann conditions
+simultaneously. We also prove a resolvent estimate for the generator of the
+damped plate semigroup associated with these boundary conditions. The spectral
+inequality allows one to observe finite sums of eigenfunctions for this
+fourth-order elliptic operator, from an arbitrary open subset of the manifold.
+Moreover, the constant that appears in the inequality grows as exp(C$\mu$ 1/4)
+where $\mu$ is the largest eigenvalue associated with the eigenfunctions
+appearing in the sum. This type of inequality is known for the Laplace
+operator. As an application, we obtain a null-controllability result for a
+higher-order parabolic equation. The resolvent estimate provides the spectral
+behavior of the plate semigroup generator on the imaginary axis. This type of
+estimate is known in the case of the damped wave semigroup. As an application ,
+we deduce a stabilization result for the damped plate equation, with a log-type
+decay. The proofs of both the spectral inequality and the resolvent estimate
+are based on the derivation of different types of Carleman estimates for an
+elliptic operator related to the bi-Laplace operator: in the interior and at
+some boundaries. One of these estimates exhibits a loss of one full derivative.
+Its proof requires the introduction of an appropriate semi-classical calculus
+and a delicate microlocal argument.",1509.02098v5
+2015-09-14,Nonlinear Energetic Particle Transport in the Presence of Multiple Alfvenic Waves in ITER,"This work presents the results of a multi mode ITER study on Toroidal Alfven
+Eigenmodes, using the nonlinear hybrid HAGIS-LIGKA model. It is found that main
+conclusions from earlier studies of ASDEX Upgrade discharges can be transferred
+to the ITER scenario: global, nonlinear effects are crucial for the evolution
+of the multi mode scenario. This work focuses on the ITER 15 MA baseline
+scenario with with a safety factor at the magnetic axis of $q_0 =$ 0.986. The
+least damped eigenmodes of the system are identified with the gyrokinetic,
+non-perturbative LIGKA solver, concerning mode structure, frequency and
+damping. Taking into account all weakly damped modes that can be identified
+linearly, nonlinear simulations with HAGIS reveal strong multi mode behavior:
+while in some parameter range, quasi-linear estimates turn out to be reasonable
+approximations for the nonlinearly relaxed energetic particle profile, under
+certain conditions low-n TAE branches can be excited. As a consequence, not
+only grow amplitudes of all modes to (up to orders of magnitude) higher values
+compared to the single mode cases but also, strong redistribution is triggered
+in the outer radial area between $\rho_\mathrm{pol} =$ 0.6 and 0.85, far above
+quasi-linear estimates.",1509.04010v1
+2015-09-30,Dynamic Quantum Tomography Model for Phase-Damping Channels,"In this article we propose a dynamic quantum tomography model for open
+quantum systems with evolution given by phase-damping channels. Mathematically,
+these channels correspond to completely positive trace-preserving maps defined
+by the Hadamard product of the initial density matrix with a time-dependent
+matrix which carries the knowledge about the evolution. Physically, there is a
+strong motivation for considering this kind of evolution because such channels
+appear naturally in the theory of open quantum systems. The main idea behind a
+dynamic approach to quantum tomography claims that by performing the same kind
+of measurement at some time instants one can obtain new data for state
+reconstruction. Thus, this approach leads to a decrease in the number of
+distinct observables which are required for quantum tomography; however, the
+exact benefit for employing the dynamic approach depends strictly on how the
+quantum system evolves in time. Algebraic analysis of phase-damping channels
+allows one to determine optimal criteria for quantum tomography of systems in
+question. General theorems and observations presented in the paper are
+accompanied by a specific example, which shows step by step how the theory
+works. The results introduced in this article can potentially be applied in
+experiments where there is a tendency a look at quantum tomography from the
+point of view of economy of measurements, because each distinct kind of
+measurement requires, in general, preparing a separate setup.",1509.09318v3
+2015-10-24,Propagation of GeV neutrinos through Earth,"We have studied the Earth matter effect on the oscillation of upward going
+GeV neutrinos by taking into account the three active neutrino flavors. For
+neutrino energy in the range 3 to 12 GeV we observed three distinct resonant
+peaks for the oscillation process $\nu_e\leftrightarrow \nu_{\mu,\tau}$ in
+three \textit{distinct} densities. However, according to the most realistic
+density profile of the Earth, the second peak at neutrino energy 6.18 GeV
+corresponding to the density $6.6\,g/cm^3$ does not exist. So the resonance at
+this energy can not be of MSW-type. For the calculation of observed flux of
+these GeV neutrinos on Earth, we considered two different flux ratios at the
+source, the standard scenario with the flux ratio $1:2:0$ and the muon damped
+scenario with $0:1:0$. It is observed that at the detector while the standard
+scenario gives the observed flux ratio $1:1:1$, the muon damped scenario has a
+different ratio. For muon damped case with $E_{\nu} < 20$ GeV, we always get
+observed neutrino fluxes as $\Phi_{\nu_e} < \Phi_{\nu_\mu}\simeq
+\Phi_{\nu_\tau}$ and for $E_{\nu} > 20$ GeV, we get the average
+$\Phi_{\nu_e}\sim 0$ and $\Phi_{\nu_\mu}\simeq \Phi_{\nu_\tau}\simeq 0.45$. The
+upcoming PINGU will be able to shed more light on the nature of the resonance
+in these GeV neutrinos and hopefully will also be able to discriminate among
+different processes of neutrino production at the source in GeV energy range.",1510.07103v2
+2015-11-18,Surface waves propagation on a turbulent flow forced electromagnetically,"We study the propagation of monochromatic surface waves on a turbulent flow.
+The flow is generated in a layer of liquid metal by an electromagnetic forcing.
+This forcing creates a quasi two-dimensional (2D) turbulence with strong
+vertical vorticity. The turbulent flow contains much more energy than the
+surface waves. In order to focus on the surface wave, the deformations induced
+by the turbulent flow are removed. This is done by performing a coherent phase
+averaging. For wavelengths smaller than the forcing lengthscale, we observe a
+significant increase of the wavelength of the propagating wave that has not
+been reported before. We suggest that it can be explained by the random
+deflection of the wave induced by the velocity gradient of the turbulent flow.
+Under this assumption, the wavelength shift is an estimate of the fluctuations
+of deflection angle. The local measurements of the wave frequency far from the
+wavemaker do not reveal such systematic behavior, although a small shift is
+measured. Finally we quantify the damping enhancement induced by the turbulent
+flow. We review various theoretical scaling laws proposed previously. Most of
+them propose a damping that increases as the square of Froude number. In
+contrast, our experimental results show a turbulent damping increasing linearly
+with the Froude number. We interpret this linear behaviour as a balance between
+the time spent by a wave to cross a turbulent structure with the turbulent
+mixing time. The larger is the ratio of these 2 times, the more energy is
+extracted from the progressive wave. Finally, mechanisms of energy exchange and
+open issues are discussed and further studies are proposed.",1511.05900v1
+2015-12-15,Correlations between compositions and orbits established by the giant impact era of planet formation,"The giant impact phase of terrestrial planet formation establishes
+connections between super-Earths' orbital properties (semimajor axis spacings,
+eccentricities, mutual inclinations) and interior compositions (the presence or
+absence of gaseous envelopes). Using N-body simulations and analytic arguments,
+we show that spacings derive not only from eccentricities, but also from
+inclinations. Flatter systems attain tighter spacings, a consequence of an
+eccentricity equilibrium between gravitational scatterings, which increase
+eccentricities, and mergers, which damp them. Dynamical friction by residual
+disk gas plays a critical role in regulating mergers and in damping
+inclinations and eccentricities. Systems with moderate gas damping and high
+solid surface density spawn gas-enveloped super-Earths with tight spacings,
+small eccentricities, and small inclinations. Systems in which super-Earths
+coagulate without as much ambient gas, in disks with low solid surface density,
+produce rocky planets with wider spacings, larger eccentricities, and larger
+mutual inclinations. A combination of both populations can reproduce the
+observed distributions of spacings, period ratios, transiting planet
+multiplicities, and transit duration ratios exhibited by Kepler super-Earths.
+The two populations, both formed in situ, also help to explain observed trends
+of eccentricity vs. planet size, and bulk density vs. method of mass
+measurement (radial velocities vs. transit timing variations). Simplifications
+made in this study --- including the limited timespan of the simulations, and
+the approximate treatments of gas dynamical friction and gas depletion history
+--- should be improved upon in future work to enable a detailed quantitative
+comparison to the observations.",1512.04951v2
+2015-12-18,Seismic waves damping with arrays of inertial resonators,"We investigate the elastic stop band properties of a theoretical cubic array
+of iron spheres connected to a bulk of concrete via iron or rubber ligaments.
+Each sphere can move freely within a surrounding air cavity, but ligaments
+couple it to the bulk and further facilitate bending and rotational motions.
+Associated low frequency local resonances are well predicted by an asymptotic
+formula. We find complete stop bands (for all wave-polarizations) in the
+frequency range $[16,21]$ Hertz (resp. $[6,11]$ Hertz) for $7.4$-meter (resp.
+$0.74$-meter) diameter iron spheres with a $10$-meter (resp. $1$-meter)
+center-to-center spacing, when they are connected to concrete via steel (resp.
+rubber) ligaments. The scattering problem shows that only bending modes are
+responsible for damping and that rotational modes are totally overwritten by
+bending modes. Regarding seismic applications, we further consider soil as a
+bulk medium, in which case the relative bandwidth of the low frequency stop
+band can be enlarged through ligaments of different sizes that allow for well
+separated bending and rotational modes. We finally achieve some damping of
+elastodynamic waves from $8$ to $49$ Hertz (relative stop band of $143$
+percent) for iron spheres $0.74$-meter in diameter that are connected to soil
+with six rubber ligaments of optimized shapes. These results represent a
+preliminary step in the design of seismic shields placed around, or underneath,
+the foundations of large civil infrastructures.",1512.06078v2
+2016-01-08,Kinetic Simulation of Slow Magnetosonic Waves and Quasi-periodic Upflows in the Solar Corona,"Quasi-periodic disturbances of emission-line parameters are frequently
+observed in the corona. These disturbances propagate upward along the magnetic
+field with speeds $\sim100~\rm{km~s}^{-1}$. This phenomenon has been
+interpreted as evidence of the propagation of slow magnetosonic waves or argued
+to be signature of the intermittent outflows superposed on the background
+plasmas. Here we aim to present a new ""wave + flow"" model to interpret these
+observations. In our scenario, the oscillatory motion is a slow mode wave, and
+the flow is associated with a beam created by the wave-particle interaction
+owing to Landau resonance. With the help of a Vlasov model, we simulate the
+propagation of the slow mode wave and the generation of the beam flow. We find
+that weak periodic beam flows can be generated owing to Landau resonance in the
+solar corona, and the phase with strongest blueward asymmetry is ahead of that
+with strongest blueshift by about 1/4 period. We also find that the slow wave
+damps to the level of 1/e after the transit time of two wave periods, owing to
+Landau damping and Coulomb collisions in our simulation. This damping time
+scale is similar to that resulting from thermal-conduction in the
+magnetohydrodynamics regime. The beam flow is weakened/attenuated with
+increasing wave period and decreasing wave amplitude since Coulomb collision
+becomes more and more dominant over the wave action. We suggest that this ""wave
++ flow"" kinetic model provides an alternative explanation for the observed
+quasi-periodic propagating perturbations in various parameters in the solar
+corona.",1601.01823v1
+2016-01-25,Comprehensive evaluation of the linear stability of Alfvén eigenmodes driven by alpha particles in an ITER baseline scenario,"The linear stability of Alfv\'en eigenmodes in the presence of fusion-born
+alpha particles is thoroughly assessed for two variants of an ITER baseline
+scenario, which differ significantly in their core and pedestal temperatures. A
+systematic approach is used that considers all possible eigenmodes for a given
+magnetic equilibrium and determines their growth rates due to alpha-particle
+drive and Landau damping on fuel ions, helium ashes and electrons. This
+extensive stability study is efficiently conducted through the use of a
+specialized workflow that profits from the performance of the hybrid MHD
+drift-kinetic code $\mbox{CASTOR-K}$ (Borba D. and Kerner W. 1999 J. Comput.
+Phys. ${\bf 153}$ 101; Nabais F. ${\it et\,al}$ 2015 Plasma Sci. Technol. ${\bf
+17}$ 89), which can rapidly evaluate the linear growth rate of an eigenmode. It
+is found that the fastest growing instabilities in the aforementioned ITER
+scenario are core-localized, low-shear toroidal Alfv\'en eigenmodes. The
+largest growth-rates occur in the scenario variant with higher core
+temperatures, which has the highest alpha-particle density and density
+gradient, for eigenmodes with toroidal mode numbers $n\approx30$. Although
+these eigenmodes suffer significant radiative damping, which is also evaluated,
+their growth rates remain larger than those of the most unstable eigenmodes
+found in the variant of the ITER baseline scenario with lower core
+temperatures, which have $n\approx15$ and are not affected by radiative
+damping.",1601.06621v1
+2016-01-27,Flash ionisation signature in coherent cyclotron emission from Brown Dwarfs,"Brown dwarfs form mineral clouds in their atmospheres, where charged
+particles can produce large-scale discharges in form of lightning resulting in
+a substantial sudden increase of local ionisation. Brown dwarfs are observed to
+emit cyclotron radio emission. We show that signatures of strong transient
+atmospheric ionisation events (flash ionisation) can be imprinted on a
+pre-existing radiation. Detection of such flash ionisation events will open
+investigations into the ionisation state and atmospheric dynamics. Such
+ionisation events can also result from explosion shock waves, bursts or
+eruptions. We present an analytical model that describes the modulation of a
+pre-existing electromagnetic radiation by a time-dependent (flash) conductivity
+that is characteristic for flash ionisation events like lightning. Our
+conductivity model reproduces the conductivity function derived from
+observations of Terrestrial Gamma Ray Flashes, and is applicable to
+astrophysical objects with strong temporal variations in the local ionization,
+as in planetary atmospheres and protoplanetary disks. We show that the field
+responds with a characteristic flash-shaped pulse to a conductivity flash of
+intermediate intensity. More powerful ionisation events result in smaller
+variations of the initial radiation, or in its damping. We show that the
+characteristic damping of the response field for high-power initial radiation
+carries information about the ionisation flash magnitude and duration. The
+duration of the pulse amplification or the damping is consistently shorter for
+larger conductivity variations and can be used to evaluate the intensity of the
+flash ionisation. Our work suggests that cyclotron emission could be probe
+signals for electrification processes inside BD atmosphere.",1601.07474v1
+2016-02-02,Sudden-quench dynamics of Bardeen-Cooper-Schrieffer states in deep optical lattices,"We determine the exact dynamics of an initial Bardeen-Cooper-Schrieffer (BCS)
+state of ultra-cold atoms in a deep hexagonal optical lattice. The dynamical
+evolution is triggered by a quench of the lattice potential, such that the
+interaction strength $U_f$ is much larger than the hopping amplitude $J_f$. The
+quench initiates collective oscillations with frequency $|U_f|/(2\pi)$ in the
+momentum occupation numbers and imprints an oscillating phase with the same
+frequency on the BCS order parameter $\Delta$. The oscillation frequency of
+$\Delta$ is not reproduced by treating the time evolution in mean-field theory.
+In our theory, the momentum noise (i.e. density-density) correlation functions
+oscillate at frequency $|U_f|/2\pi$ as well as at its second harmonic. For a
+very deep lattice, with zero tunneling energy, the oscillations of momentum
+occupation numbers are undamped. Non-zero tunneling after the quench leads to
+dephasing of the different momentum modes and a subsequent damping of the
+oscillations. The damping occurs even for a finite-temperature initial BCS
+state, but not for a non-interacting Fermi gas. Furthermore, damping is
+stronger for larger order parameter and may therefore be used as a signature of
+the BCS state. Finally, our theory shows that the noise correlation functions
+in a honeycomb lattice will develop strong anti-correlations near the Dirac
+point.",1602.00979v2
+2016-03-09,Conclusive Identification of Quantum Channels via Monogamy of Quantum Correlations,"We investigate the action of local and global noise on monogamy of quantum
+correlations, when monogamy scores are considered as observables, and
+three-qubit systems are subjected to global noise and various local noisy
+channels, namely, amplitude-damping, phase-damping, and depolarizing channels.
+We show that the dynamics of monogamy scores corresponding to negativity and
+quantum discord, in the case of generalized W states, as inputs to the noisy
+channels, can exhibit non-monotonic dynamics with respect to increasing noise
+parameter, which is in contrast to the monotonic decay of monogamy scores when
+generalized Greenberger-Horne-Zeilinger states are exposed to noise. We
+quantify the persistence of monogamy against noise via a characteristic value
+of the noise parameter, and show that depolarizing noise destroys monogamy of
+quantum correlation faster compared to other noisy channels. We demonstrate
+that the negativity monogamy score is more robust than the quantum discord
+monogamy score, when the noise is of the phase-damping type. We also
+investigate the variation of monogamy with increasing noise for arbitrary
+three-qubit pure states as inputs. Finally, depending on these results, we
+propose a two-step protocol, which can conclusively identify the type of noise
+applied to the quantum system, by using generalized Greenberger-Horne-Zeilinger
+and generalized W states as resource states. We discuss a possible
+generalization of the results to higher number of parties.",1603.02801v3
+2016-05-05,Electromagnetic fields in the exterior of an oscillating relativistic star -- II. Electromagnetic damping,"An important issue in the asteroseismology of compact and magnetized stars is
+the determination of the dissipation mechanism which is most efficient in
+damping the oscillations when these are produced. In a linear regime and for
+low-multipolarity modes these mechanisms are confined to either
+gravitational-wave or electromagnetic losses. We here consider the latter and
+compute the energy losses in the form of Poynting fluxes, Joule heating and
+Ohmic dissipation in a relativistic oscillating spherical star with a dipolar
+magnetic field in vacuum. While this approach is not particularly realistic for
+rapidly rotating stars, it has the advantage that it is fully analytic and that
+it provides expressions for the electric and magnetic fields produced by the
+most common modes of oscillation both in the vicinity of the star and far away
+from it. In this way we revisit and extend to a relativistic context the
+classical estimates of McDermott et al. Overall, we find that
+general-relativistic corrections lead to electromagnetic damping time-scales
+that are at least one order of magnitude smaller than in Newtonian gravity.
+Furthermore, with the only exception of $g$ (gravity) modes, we find that $f$
+(fundamental), $p$ (pressure), $i$ (interface) and $s$ (shear) modes are
+suppressed more efficiently by gravitational losses than by electromagnetic
+ones.",1605.01709v1
+2016-06-14,Landau damping to partially locked states in the Kuramoto model,"In the Kuramoto model of globally coupled oscillators, partially locked
+states (PLS) are stationary solutions that incorporate the emergence of partial
+synchrony when the interaction strength increases. While PLS have long been
+considered, existing results on their stability are limited to neutral
+stability of the linearized dynamics in strong topology, or to specific
+invariant subspaces (obtained via the so-called Ott-Antonsen (OA) ansatz) with
+specific frequency distributions for the oscillators. In the mean field limit,
+the Kuramoto model shows various ingredients of the Landau damping mechanism in
+the Vlasov equation. This analogy has been a source of inspiration for
+stability proofs of regular Kuramoto equilibria. Besides, the major
+mathematical issue with PLS asymptotic stability is that these states consist
+of heterogeneous and singular measures. Here, we establish an explicit
+criterion for their spectral stability and we prove their local asymptotic
+stability in weak topology, for a large class of analytic frequency marginals.
+The proof strongly relies on a suitable functional space that contains (Fourier
+transforms of) singular measures, and for which the linearized dynamics is well
+under control. For illustration, the stability criterion is evaluated in some
+standard examples. We show in particular that no loss of generality results in
+assuming the OA ansatz. To our best knowledge, our result provides the first
+proof of Landau damping to heterogeneous and irregular equilibria, in absence
+of dissipation.",1606.04470v1
+2016-07-20,Electromagnon in the Z-type hexaferrite $({\rm Ba}_{x}{\rm Sr}_{1-x})_3\rm Co_2Fe_{24}O_{41}$,"We studied experimentally the high-temperature magnetoelectric $({\rm
+Ba}_{x}{\rm Sr}_{1-x})_3\rm Co_2Fe_{24}O_{41}$ prepared as ceramics (x = 0,
+0.2) and a single crystal (x = 0.5) using inelastic neutron scattering, THz
+time-domain, Raman and far-infrared spectroscopies. The spectra, measured with
+varying temperature and magnetic field, reveal rich information about the
+collective spin and lattice excitations. In the ceramics, we observed an
+infrared-active magnon which is absent in $E^{\omega}\perp z$ polarized THz
+spectra of the crystal, and we assume that it is an electromagnon active in
+$E^{\omega} \| z$ polarized spectra. On heating from 7 to 250 K, the frequency
+of this electromagnon drops from 36 to 25 cm$^{-1}$ and its damping gradually
+increases, so it becomes overdamped at room temperature. Applying external
+magnetic field has a similar effect on the damping and frequency of the
+electromagnon, and the mode is no more observable in the THz spectra above 2 T,
+as the transverse-conical magnetic structure transforms into a collinear one.
+Raman spectra reveal another spin excitation with a slightly different
+frequency and much higher damping. Upon applying magnetic field higher than 3
+T, in the low-frequency part of the THz spectra, a narrow excitation appears
+whose frequency linearly increases with magnetic field. We interpret this
+feature as the ferromagnetic resonance.",1607.05878v1
+2016-07-28,Damping of the Milky Way bar by manifold-driven spirals,"We describe a new phenomenon of `bar damping' that may have played an
+important role in shaping the Milky Way bar and bulge as well as its spiral
+structure. We use a collisionless N-body simulation of a Milky Way-like galaxy
+initially composed of a dark matter halo and an exponential disk with Toomre
+parameter slightly above unity. In this configuration, dominated by the disk in
+the center, a bar forms relatively quickly, after 1 Gyr of evolution. This is
+immediately followed by the formation of two manifold-driven spiral arms and
+the outflow of stars that modifies the potential in the vicinity of the bar,
+apparently shifting the position of the L_1/L_2 Lagrange points. This
+modification leads to the shortening of the bar and the creation of a next
+generation of manifold-driven spiral arms at a smaller radius. The process
+repeats itself a few times over the next 0.5 Gyr resulting in further
+substantial weakening and shortening of the bar. The time when the damping
+comes to an end coincides with the first buckling episode in the bar which
+rebuilds the orbital structure so that no more new spiral arms are formed. The
+morphology of the bar and the spiral structure at this time show remarkable
+similarity to the present properties of the Milky Way. Later on, the bar starts
+to grow rather steadily again, weakened only by subsequent buckling episodes
+occurring at more distant parts of the disk.",1607.08339v2
+2016-11-29,Dissipative self-gravitating Bose-Einstein condensates with arbitrary nonlinearity as a model of dark matter halos,"We develop a general formalism applying to Newtonian self-gravitating
+Bose-Einstein condensates. This formalism may find application in the context
+of dark matter halos. We introduce a generalized Gross-Pitaevskii equation
+including a source of dissipation (damping) and an arbitrary nonlinearity.
+Using the Madelung transformation, we derive the hydrodynamic representation of
+this generalized Gross-Pitaevskii equation and obtain a damped quantum Euler
+equation involving a friction force proportional and opposite to the velocity
+and a pressure force associated with an equation of state determined by the
+nonlinearity present in the generalized Gross-Pitaevskii equation. In the
+strong friction limit, we obtain a quantum Smoluchowski equation. These
+equations satisfy an $H$-theorem for a free energy functional constructed with
+a generalized entropy. We specifically consider the Boltzmann and Tsallis
+entropies associated with isothermal and polytropic equations of state. We also
+consider the entropy associated with the logotropic equation of state. We
+derive the virial theorem corresponding to the generalized Gross-Pitaevskii
+equation, damped quantum Euler equation, and quantum Smoluchowski equation.
+Using a Gaussian ansatz, we obtain a simple equation governing the dynamical
+evolution of the size of the condensate. We highlight a specific model of dark
+matter halos corresponding to a generalized Gross-Pitaevskii equation with a
+logarithmic nonlinearity and a cubic nonlinearity. It leads to dark matter
+halos with an equation of state $P=\rho k_B T_{\rm eff}/m+2\pi
+a_s\hbar^2\rho^{2}/m^3$ presenting a condensed core (BEC/soliton) and an
+isothermal halo with an effective temperature $T_{\rm eff}$. We propose that
+this model provides an effective coarse-grained parametrization of dark matter
+halos experiencing gravitational cooling.",1611.09610v1
+2016-12-06,Breakdown of Fermi liquid theory in topological multi-Weyl semimetals,"Fermi liquid theory works very well in most normal metals, but is found
+violated in many strongly correlated electron systems, such as cuprate and
+heavy-fermion superconductors. A widely accepted criterion is that, the Fermi
+liquid theory is valid when the interaction-induced fermion damping rate
+approaches zero more rapidly than the energy. Otherwise, it is invalid. Here,
+we demonstrate that this criterion breaks down in topological double-and
+triple-Weyl semimetals. Renormalization group analysis reveals that, although
+the damping rate of double- and triple-Weyl fermions induced by the Coulomb
+interaction approaches zero more rapidly than the energy, the quasiparticle
+residue vanishes and the Fermi liquid theory is invalid. This behavior
+indicates a weaker-than-marginal violation of the Fermi liquid theory. Such an
+unconventional non-Fermi liquid state originates from the special dispersion of
+double- and triple-Weyl fermions, and is qualitatively different from all the
+other Fermi-liquid and non-Fermi-liquid states. The predicted properties of the
+fermion damping rate and the spectral function can be probed by the
+angle-resolved photoemission spectroscopy. The density of states, specific
+heat, and conductivities are also calculated and analyzed after incorporating
+the corrections induced by the Coulomb interaction.",1612.01729v2
+2016-12-08,Quantifying acoustic damping using flame chemiluminescence,"Thermoacoustic instabilities in gas turbines and aeroengine combustors falls
+within the category of complex systems. They can be described
+phenomenologically using nonlinear stochastic differential equations, which
+constitute the grounds for output-only model-based system identification. It
+has been shown recently that one can extract the governing parameters of the
+instabilities, namely the linear growth rate and the nonlinear component of the
+thermoacoustic feedback, using dynamic pressure time series only. This is
+highly relevant for practical systems, which cannot be actively controlled due
+to a lack of cost-effective actuators. The thermoacoustic stability is given by
+the linear growth rate, which results from the combination of the acoustic
+damping and the coherent feedback from the flame. In this paper, it is shown
+that it is possible to quantify the acoustic damping of the system, and thus to
+separate its contribution to the linear growth rate from the one of the flame.
+This is achieved by post-processing in a simple way simultaneously acquired
+chemiluminescence and acoustic pressure data. It provides an additional
+approach to further unravel from observed time series the key mechanisms
+governing the system dynamics. This straightforward method is illustrated here
+using experimental data from a combustion chamber operated at several linearly
+stable and unstable operating conditions.",1612.02609v1
+2016-12-29,A quasi-mode theory of chiral phonons,"The coherence properties of mechanical resonators are often limited by
+multiple unavoidable forms of loss -- including phonon-phonon and phonon-defect
+scattering -- which result in the scattering of sound into other resonant modes
+and into the phonon bath. Dynamic suppression of this scattering loss can lift
+constraints on device structure and can improve tolerance to defects in the
+material, even after fabrication. Inspired by recent experiments, here we
+introduce a model of phonon losses resulting from disorder in a whispering
+gallery mode resonator with acousto-optical coupling between optical and
+mechanical modes. We show that a typical elastic scattering mechanism of high
+quality factor (Q) mechanical modes flips the direction of phonon propagation
+via high-angle scattering, leading to damping into modes with the opposite
+parity. When the optical mode overlaps co-propagating high-Q and bulk
+mechanical modes, the addition of laser cooling via sideband-resolved damping
+of the mechanical mode of a chosen parity also damps and modifies the response
+of the bulk modes of the same parity. This, in turn, simultaneously improves
+the quality factor and reduces the thermal load of the counter-propagating
+high-Q modes, leading to the dynamical creation of a cold phononic shield. We
+compare our theoretical results to the recent experiments of Kim et al., and
+find quantitative agreement with our theory.",1612.09240v1
+2017-01-03,A Model for Dissipation of Solar Wind Magnetic Turbulence by Kinetic Alfvén Waves at Electron Scales: Comparison with Observations,"In hydrodynamic turbulence, it is well established that the length of the
+dissipation scale depends on the energy cascade rate, i.e., the larger the
+energy input rate per unit mass, the more the turbulent fluctuations need to be
+driven to increasingly smaller scales to dissipate the larger energy flux.
+Observations of magnetic spectral energy densities indicate that this intuitive
+picture is not valid in solar wind turbulence. Dissipation seems to set in at
+the same length scale for different solar wind conditions independently of the
+energy flux. To investigate this difference in more detail, we present an
+analytic dissipation model for solar wind turbulence at electron scales, which
+we compare with observed spectral densities. Our model combines the energy
+transport from large to small scales and collisionless damping, which removes
+energy from the magnetic fluctuations in the kinetic regime. We assume
+wave-particle interactions of kinetic Alfv\'{e}n waves (KAW) to be the main
+damping process. Wave frequencies and damping rates of KAW are obtained from
+the hot plasma dispersion relation. Our model assumes a critically balanced
+turbulence, where larger energy cascade rates excite larger parallel
+wavenumbers for a certain perpendicular wavenumber. If the dissipation is
+additionally wave driven such that the dissipation rate is proportional to the
+parallel wavenumber - as with KAW - then an increase of the energy cascade rate
+is counter-balanced by an increased dissipation rate for the same perpendicular
+wavenumber leading to a dissipation length independent of the energy cascade
+rate.",1701.00680v1
+2017-02-07,Constraining color flavor locked strange stars in the gravitational wave era,"We perform a detailed analysis of the fundamental mode of non-radial
+pulsations of color flavor locked strange stars. Solving the general
+relativistic equations for non-radial pulsations for an equation of state
+derived within the MIT bag model, we calculate the frequency and the
+gravitational damping time of the fundamental mode for all the parametrizations
+of the equation of state that lead to self-bound matter.
+  Our results show that color flavor locked strange stars can emit
+gravitational radiation in the optimal range for present gravitational wave
+detectors and that it is possible to constrain the equation of state's
+parameters if the fundamental oscillation mode is observed and the stellar mass
+is determined.
+  We also show that the $f$-mode frequency can be fitted as a function of the
+square root of the average stellar density $\sqrt{M/R^3}$ by a single linear
+relation that fits quite accurately the results for all parametrizations of the
+equation of state. All results for the damping time can also be fitted as a
+function of the compactness $M/R$ by a single empirical relation. Therefore, if
+a given compact object is identified as a color flavor locked strange star
+these two relations could be used to determine the mass and the radius from the
+knowledge of the frequency and the damping time of gravitational waves from the
+$f$ mode.",1702.02081v1
+2017-02-16,"Designing the Optimal Bit: Balancing Energetic Cost, Speed and Reliability","We consider the technologically relevant costs of operating a reliable bit
+that can be erased rapidly. We find that both erasing and reliability times are
+non-monotonic in the underlying friction, leading to a trade-off between
+erasing speed and bit reliability. Fast erasure is possible at the expense of
+low reliability at moderate friction, and high reliability comes at the expense
+of slow erasure in the underdamped and overdamped limits. Within a given class
+of bit parameters and control strategies, we define ""optimal"" designs of bits
+that meet the desired reliability and erasing time requirements with the lowest
+operational work cost. We find that optimal designs always saturate the bound
+on the erasing time requirement, but can exceed the required reliability time
+if critically damped. The non-trivial geometry of the reliability and erasing
+time-scales allows us to exclude large regions of parameter space as
+sub-optimal. We find that optimal designs are either critically damped or close
+to critical damping under the erasing procedure.",1702.04950v2
+2017-02-16,Effects of Landau damping on ion-acoustic solitary waves in a semiclassical plasma,"We study the nonlinear propagation of ion-acoustic waves (IAWs) in an
+unmagnetized collisionless plasma with the effects of electron and ion Landau
+damping in the weak quantum (semiclassical) regime, i.e., when the typical
+ion-acoustic (IA) length scale is larger than the thermal de Broglie
+wavelength. Starting from a set of classical and semiclassical Vlasov equations
+for ions and electrons, coupled to the Poisson equation, we derive a modified
+(by the particle dispersion) Korteweg-de Vries (KdV) equation which governs the
+evolution of IAWs with the effects of wave-particle resonance. It is found that
+in contrast to the classical results, the nonlinear IAW speed $(\lambda)$ and
+the linear Landau damping rate $(\gamma)$ are no longer constants, but can vary
+with the wave number $(k)$ due to the quantum particle dispersion. The effects
+of the quantum parameter $H$ (the ratio of the plasmon energy to the thermal
+energy) and the electron to ion temperature ratio $(T)$ on the profiles of
+$\lambda$, $\gamma$ and the solitary wave amplitude are also studied. It is
+shown that the decay rate of the wave amplitude is reduced by the effects of
+$H$.",1702.05035v2
+2017-03-07,Higgs Modes in the Pair Density Wave Superconducting State,"The pair density wave (PDW) superconducting state has been proposed to
+explain the layer- decoupling effect observed in the compound
+La$_{2-x}$Ba$_x$CuO$_4$ at $x=1/8$ (Phys. Rev. Lett. 99, 127003). In this state
+the superconducting order parameter is spatially modulated, in contrast with
+the usual superconducting (SC) state where the order parameter is uniform. In
+this work, we study the properties of the amplitude (Higgs) modes in a
+unidirectional PDW state. To this end we consider a phenomenological model of
+PDW type states coupled to a Fermi surface of fermionic quasiparticles. In
+contrast to conventional superconductors that have a single Higgs mode,
+unidirectional PDW superconductors have two Higgs modes. While in the PDW state
+the Fermi surface largely remains gapless, we find that the damping of the PDW
+Higgs modes into fermionic quasiparticles requires exceeding an energy
+threshold. We show that this suppression of damping in the PDW state is due to
+kinematics. As a result, only one of the two Higgs modes is significantly
+damped. In addition, motivated by the experimental phase diagram, we discuss
+the mixing of Higgs modes in the coexistence regime of the PDW and uniform SC
+states. These results should be observable directly in a Raman spectroscopy, in
+momentum resolved electron energy loss spectroscopy, and in resonant inelastic
+X-ray scattering, thus providing evidence of the PDW states.",1703.02541v2
+2017-04-29,Low-frequency wide band-gap elastic/acoustic meta-materials using the K-damping concept,"The terms ""acoustic/elastic meta-materials"" describe a class of periodic
+structures with unit cells exhibiting local resonance. This localized resonant
+structure has been shown to result in negative effective stiffness and/or mass
+at frequency ranges close to these local resonances. As a result, these
+structures present unusual wave propagation properties at wavelengths well
+below the regime corresponding to band-gap generation based on spatial
+periodicity, (i.e. ""Bragg scattering""). Therefore, acoustic/elastic
+meta-materials can lead to applications, especially suitable in the
+low-frequency range. However, low frequency range applications of such
+meta-materials require very heavy internal moving masses, as well as additional
+constraints at the amplitudes of the internally oscillating locally resonating
+structures, which may prohibit their practical implementation. In order to
+resolve this disadvantage, the K-Damping concept will be analyzed. According to
+this concept, the acoustic/elastic meta-materials are designed to include
+negative stiffness elements instead or in addition to the internally resonating
+added masses. This concept removes the need for the heavy locally added heavy
+masses, while it simultaneously exploits the negative stiffness damping
+phenomenon. Application of both Bloch's theory and the classical modal analysis
+at the one-dimensional mass-in-mass lattice is analyzed and corresponding
+dispersion relations are derived. The results indicate significant advantages
+over the conventional mass-in-a mass lattice, such as broader band-gaps and
+increased damping ratio and reveal significant potential in the proposed
+solution. Preliminary feasibility analysis for seismic meta-structures and low
+frequency acoustic isolation-damping confirm the strong potential and
+applicability of this concept.",1705.00226v2
+2017-05-07,Precision cosmology with redshift-space bispectrum: a perturbation theory based model at one-loop order,"The large-scale matter distribution in the late-time Universe exhibits
+gravity-induced non-Gaussianity, and the bispectrum, three-point cumulant is
+expected to contain significant cosmological information. In particular, the
+measurement of the bispectrum helps to tighten the constraints on dark energy
+and modified gravity through the redshift-space distortions (RSD). In this
+paper, extending the work by Taruya, Nishimichi & Saito (2010, Phys.Rev.D 82,
+063522), we present a perturbation theory (PT) based model of redshift-space
+matter bispectrum that can keep the non-perturbative damping effect under
+control. Characterizing this non-perturbative damping by a univariate function
+with single free parameter, the PT model of the redshift-space bispectrum is
+tested against a large set of cosmological $N$-body simulations, finding that
+the predicted monopole and quadrupole moments are in a good agreement with
+simulations at the scales of baryon acoustic oscillations (well beyond the
+range of agreement of standard PT). The validity of the univariate ansatz of
+the damping effect is also examined, and with the PT calculation at
+next-to-leading order, the fitted values of the free parameter is shown to
+consistently match those obtained from the PT model of power spectrum by
+Taruya, Nishimichi & Saito (2010).",1705.02574v1
+2017-05-13,Large-amplitude longitudinal oscillations in a solar filament,"In this paper, we report our multiwavelength observations of the
+large-amplitude longitudinal oscillations of a filament on 2015 May 3. Located
+next to active region 12335, the sigmoidal filament was observed by the
+ground-based H$\alpha$ telescopes from GONG and by AIA aboard SDO. The filament
+oscillations were most probably triggered by the magnetic reconnection in the
+filament channel. The directions of oscillations have angles of
+4$^\circ$-36$^\circ$ with respect to the filament axis. The whole filament did
+not oscillate in phase as a rigid body. Meanwhile, the periods (3100$-$4400 s)
+of oscillations have a spatial dependence. The values of $R$ are estimated to
+be 69.4$-$133.9 Mm, and the minimum transverse magnetic field of the dips is
+estimated to be 15 G. The amplitudes of S5-S8 grew with time, while the
+amplitudes of S9-S14 damped with time. The amplitudes of oscillations range
+from a few to ten Mm, and the maximal velocity can reach 30 km s$^{-1}$.
+Interestingly, the filament experienced mass drainage southwards at a speed of
+$\sim$27 km s$^{-1}$. The oscillations continued after the mass drainage and
+lasted for more than 11 hr. After the mass drainage, the phases of oscillations
+did not change a lot. The periods of S5-S8 decreased, while the periods of
+S9-S14 increased. The amplitudes of S5$-$S8 damped with time, while the
+amplitudes of S9-S14 grew. Most of the damping (growing) ratios are between -9
+and 14. We propose a schematic cartoon to explain the complex behaviors of
+oscillations by introducing thread-thread interaction.",1705.04820v1
+2017-05-14,Inter-Area Oscillation Damping With Non-Synchronized Wide-Area Power System Stabilizer,"One of the major issues in an interconnected power system is the low damping
+of inter-area oscillations which significantly reduces the power transfer
+capability. Advances in Wide-Area Measurement System (WAMS) makes it possible
+to use the information from geographical distant location to improve power
+system dynamics and performances. A speed deviation based Wide-Area Power
+System Stabilizer (WAPSS) is known to be effective in damping inter-area modes.
+However, the involvement of wide-area signals gives rise to the problem of
+time-delay, which may degrade the system performance. In general, time-stamped
+synchronized signals from Phasor Data Concentrator (PDC) are used for WAPSS, in
+which delays are introduced in both local and remote signals. One can opt for a
+feedback of remote signal only from PDC and uses the local signal as it is
+available, without time synchronization. This paper utilizes configurations of
+time-matched synchronized and nonsychronized feedback and provides the
+guidelines to design the controller. The controllers are synthesized using
+$H_\infty$ control with regional pole placement for ensuring adequate dynamic
+performance. To show the effectiveness of the proposed approach, two power
+system models have been used for the simulations. It is shown that the
+controllers designed based on the nonsynchronized signals are more robust to
+time time delay variations than the controllers using synchronized signal.",1705.04953v2
+2017-06-16,Challenges testing the no-hair theorem with gravitational waves,"General relativity's no-hair theorem states that isolated astrophysical black
+holes are described by only two numbers: mass and spin. As a consequence, there
+are strict relationships between the frequency and damping time of the
+different modes of a perturbed Kerr black hole. Testing the no-hair theorem has
+been a longstanding goal of gravitational-wave astronomy. The recent detection
+of gravitational waves from black hole mergers would seem to make such tests
+imminent. We investigate how constraints on black hole ringdown parameters
+scale with the loudness of the ringdown signal---subject to the constraint that
+the post-merger remnant must be allowed to settle into a perturbative,
+Kerr-like state. In particular, we require that---for a given detector---the
+gravitational waveform predicted by numerical relativity is indistinguishable
+from an exponentially damped sine after time $t^\text{cut}$. By requiring the
+post-merger remnant to settle into such a perturbative state, we find that
+confidence intervals for ringdown parameters do not necessarily shrink with
+louder signals. In at least some cases, more sensitive measurements probe later
+times without necessarily providing tighter constraints on ringdown frequencies
+and damping times. Preliminary investigations are unable to explain this result
+in terms of a numerical relativity artifact.",1706.05152v2
+2017-06-26,Simulating the effect of high column density absorbers on the one-dimensional Lyman-alpha forest flux power spectrum,"We measure the effect of high column density absorbing systems of neutral
+hydrogen (HI) on the one-dimensional (1D) Lyman-alpha forest flux power
+spectrum using cosmological hydrodynamical simulations from the Illustris
+project. High column density absorbers (which we define to be those with HI
+column densities $N(\mathrm{HI}) > 1.6 \times
+10^{17}\,\mathrm{atoms}\,\mathrm{cm}^{-2}$) cause broadened absorption lines
+with characteristic damping wings. These damping wings bias the 1D Lyman-alpha
+forest flux power spectrum by causing absorption in quasar spectra away from
+the location of the absorber itself. We investigate the effect of high column
+density absorbers on the Lyman-alpha forest using hydrodynamical simulations
+for the first time. We provide templates as a function of column density and
+redshift, allowing the flexibility to accurately model residual contamination,
+i.e., if an analysis selectively clips out the largest damping wings. This
+flexibility will improve cosmological parameter estimation, e.g., allowing more
+accurate measurement of the shape of the power spectrum, with implications for
+cosmological models containing massive neutrinos or a running of the spectral
+index. We provide fitting functions to reproduce these results so that they can
+be incorporated straightforwardly into a data analysis pipeline.",1706.08532v2
+2017-07-19,Engineering elliptical spin-excitations by complex anisotropy fields in Fe adatoms and dimers on Cu(111),"We investigate the dynamics of Fe adatoms and dimers deposited on the Cu(111)
+metallic surface in the presence of spin-orbit coupling, within time-dependent
+density functional theory. The \textit{ab initio} results provide
+material-dependent parameters that can be used in semiclassical approaches,
+which are used for insightful interpretations of the excitation modes. By
+manipulating the surroundings of the magnetic elements, we show that elliptical
+precessional motion may be induced through the modification of the magnetic
+anisotropy energy. We also demonstrate how different kinds of spin precession
+are realized, considering the symmetry of the magnetic anisotropy energy, the
+ferro- or antiferromagnetic nature of the exchange coupling between the
+impurities, and the strength of the magnetic damping. In particular, the normal
+modes of a dimer depend on the initial magnetic configuration, changing
+drastically by going from a ferromagnetic metastable state to the
+antiferromagnetic ground state. By taking into account the effect of the
+damping into their resonant frequencies, we reveal that an important
+contribution arises for strongly biaxial systems and specially for the
+antiferromagnetic dimers with large exchange couplings. Counter intuitively,
+our results indicate that the magnetic damping influences the quantum
+fluctuations by decreasing the zero-point energy of the system.",1707.06087v2
+2017-08-16,Effects of group velocity and multi-plasmon resonances on the modulation of Langmuir waves in a degenerate plasma,"We study the nonlinear wave modulation of Langmuir waves (LWs) in a fully
+degenerate plasma. Using the Wigner-Moyal equation coupled to the Poisson
+equation and the multiple scale expansion technique, a modified nonlocal
+nonlinear Schr{\""{o}}dinger (NLS) equation is derived which governs the
+evolution of LW envelopes in degenerate plasmas. The nonlocal nonlinearity in
+the NLS equation appears due to the group velocity and multi-plasmon
+resonances, i.e., resonances induced by the simultaneous particle absorption of
+multiple wave quanta. We focus on the regime where the resonant velocity of
+electrons is larger than the Fermi velocity and thereby the linear Landau
+damping is forbidden. As a result, the nonlinear wave-particle resonances due
+to the group velocity and multi-plasmon processes are the dominant mechanisms
+for wave-particle interaction. It is found that in contrast to classical or
+semiclassical plasmas, the group velocity resonance does not necessarily give
+rise the wave damping in the strong quantum regime where $ \hbar k\sim mv_{F}$
+with $\hbar$ denoting the reduced Planck's constant, $m$ the electron mass and
+$v_F$ the Fermi velocity, however, the three-plasmon process plays a dominant
+role in the nonlinear Landau damping of wave envelopes. In this regime, the
+decay rate of the wave amplitude is also found to be higher compared to that in
+the modest quantum regime where the multi-plasmon effects are forbidden.",1708.04965v3
+2017-10-02,The gas and stellar mass of low-redshift damped Lyman-$α$ absorbers,"We report Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet
+and Arecibo Telescope H{\sc i} 21cm spectroscopic studies of six damped and
+sub-damped Lyman-$\alpha$ absorbers (DLAs and sub-DLAs, respectively) at $z
+\lesssim 0.1$, that have yielded estimates of their H{\sc i} column density,
+metallicity and atomic gas mass. This significantly increases the number of
+DLAs with gas mass estimates, allowing the first comparison between the gas
+masses of DLAs and local galaxies. Including three absorbers from the
+literature, we obtain H{\sc i} masses $\approx (0.24 - 5.2) \times 10^9 \: {\rm
+M}_\odot$, lower than the knee of the local H{\sc i} mass function. This
+implies that massive galaxies do not dominate the absorption cross-section for
+low-$z$ DLAs. We use Sloan Digital Sky Survey photometry and spectroscopy to
+identify the likely hosts of four absorbers, obtaining low stellar masses,
+$\approx 10^7-10^{8.7} M_\odot$, in all cases, consistent with the hosts being
+dwarf galaxies. We obtain high H{\sc i} 21\,cm or CO emission line widths,
+$\Delta V_{20} \approx 100-290$~km~s$^{-1}$, and high gas fractions, $f_{\rm
+HI} \approx 5-100$, suggesting that the absorber hosts are gas-rich galaxies
+with low star formation efficiencies. However, the H{\sc i} 21\,cm velocity
+spreads ($\gtrsim 100$~km~s$^{-1}$) appear systematically larger than the
+velocity spreads in typical dwarf galaxies.",1710.00710v1
+2017-10-25,Two-Level System Damping in a Quasi-One-Dimensional Optomechanical Resonator,"Nanomechanical resonators have demonstrated great potential for use as
+versatile tools in a number of emerging quantum technologies. For such
+applications, the performance of these systems is restricted by the decoherence
+of their fragile quantum states, necessitating a thorough understanding of
+their dissipative coupling to the surrounding environment. In bulk amorphous
+solids, these dissipation channels are dominated at low temperatures by
+parasitic coupling to intrinsic two-level system (TLS) defects, however, there
+remains a disconnect between theory and experiment on how this damping
+manifests in dimensionally-reduced nanomechanical resonators. Here, we present
+an optomechanically-mediated thermal ringdown technique, which we use to
+perform simultaneous measurements of the dissipation in four mechanical modes
+of a cryogenically-cooled silicon nanoresonator, with resonant frequencies
+ranging from 3 - 19 MHz. Analyzing the device's mechanical damping rate at
+fridge temperatures between 10 mK - 10 K, we demonstrate quantitative agreement
+with the standard tunneling model for TLS ensembles confined to one dimension.
+From these fits, we extract the defect density of states ($P_0 \sim$ 1 - 4
+$\times$ 10$^{44}$ J$^{-1}$ m$^{-3}$) and deformation potentials ($\gamma \sim$
+1 - 2 eV), showing that each mechanical mode couples on average to less than a
+single thermally-active defect at 10 mK.",1710.09439v3
+2017-11-10,"Vortex axisymmetrization, inviscid damping, and vorticity depletion in the linearized 2D Euler equations","Coherent vortices are often observed to persist for long times in turbulent
+2D flows even at very high Reynolds numbers and are observed in experiments and
+computer simulations to potentially be asymptotically stable in a weak sense
+for the 2D Euler equations. We consider the incompressible 2D Euler equations
+linearized around a radially symmetric, strictly monotone decreasing vorticity
+distribution. For sufficiently regular data, we prove the inviscid damping of
+the $\theta$-dependent radial and angular velocity fields with the optimal
+rates $\|u^r(t)\| \lesssim \langle t \rangle^{-1}$ and $\|u^\theta(t)\|
+\lesssim \langle t \rangle^{-2}$ in the appropriate radially weighted $L^2$
+spaces. We moreover prove that the vorticity weakly converges back to radial
+symmetry as $t \rightarrow \infty$, a phenomenon known as vortex
+axisymmetrization in the physics literature, and characterize the dynamics in
+higher Sobolev spaces. Furthermore, we prove that the $\theta$-dependent
+angular Fourier modes in the vorticity are ejected from the origin as $t \to
+\infty$, resulting in faster inviscid damping rates than those possible with
+passive scalar evolution. This non-local effect is called vorticity depletion.
+Our work appears to be the first to find vorticity depletion relevant for the
+dynamics of vortices.",1711.03668v1
+2017-11-15,Anomalous spin-orbit torque switching due to field-like torque-assisted domain wall reflection,"Spin-orbit torques (SOT) allow the electrical control of magnetic states.
+Current-induced SOT switching of the perpendicular magnetization is of
+particular technological importance. The SOT consists of damping-like and
+field-like torques so that the efficient SOT switching requires to understand
+combined effects of the two torque-components. Previous quasi-static
+measurements have reported an increased switching probability with the width of
+current pulses, as predicted with considering the damping-like torque only.
+Here we report a decreased switching probability at longer pulse-widths, based
+on time-resolved measurements. Micromagnetic analysis reveals that this
+anomalous SOT switching results from domain wall reflections at sample edges.
+The domain wall reflection is found to strongly depend on the field-like torque
+and its relative sign to the damping-like torque. Our result demonstrates a key
+role of the field-like torque in the deterministic SOT switching and notifies
+the importance of sign correlation of the two torque-components, which may shed
+light on the SOT switching mechanism.",1711.05367v1
+2017-11-24,Influence of surfactants on the electrohydrodynamic stretching of water drops in oil,"In this paper we present experimental and numerical studies of the
+electrohydrodynamic stretching of a sub-millimetre-sized salt water drop,
+immersed in oil with added non-ionic surfactant, and subjected to a suddenly
+applied electric field of magnitude approaching 1 kV/mm. By varying the drop
+size, electric field strength and surfactant concentration we cover the whole
+range of electric capillary numbers ($Ca_E$) from 0 up to the limit of drop
+disintegration. The results are compared with the analytical result by Taylor
+(1964) which predicts the asymptotic deformation as a function of $Ca_E$. We
+find that the addition of surfactant damps the transient oscillations and that
+the drops may be stretched slightly beyond the stability limit found by Taylor.
+We proceed to study the damping of the oscillations, and show that increasing
+the surfactant concentration has a dual effect of first increasing the damping
+at low concentrations, and then increasing the asymptotic deformation at higher
+concentrations. We explain this by comparing the Marangoni forces and the
+interfacial tension as the drops deform. Finally, we have observed in the
+experiments a significant hysteresis effect when drops in oil with large
+concentration of surfactant are subjected to repeated deformations with
+increasing electric field strengths. This effect is not attributable to the
+flow nor the interfacial surfactant transport.",1711.08969v2
+2017-11-30,Model-independent analysis of the DAMPE excess,"The Dark Matter Particle Explorer (DAMPE) recently released measurements of
+the electron spectrum with a hint of a narrow peak at about 1.4 TeV. We
+investigate dark matter (DM) models that could produce such a signal by
+annihilation in a nearby subhalo whilst simultaneously satisfying constraints
+from DM searches. In our model-independent approach, we consider all
+renormalizable interactions via a spin 0 or 1 mediator between spin 0 or 1/2 DM
+particles and the Standard Model leptons. We find that of the 20 combinations,
+10 are ruled out by velocity or helicity suppression of the annihilation cross
+section to fermions. The remaining 10 models, though, evade constraints from
+the relic density, collider and direct detection searches, and include models
+of spin 0 and 1/2 DM coupling to a spin 0 or 1 mediator. We delineate the
+regions of mediator mass and couplings that could explain the DAMPE excess. In
+all cases the mediator is required to be heaver than about 2 TeV by LEP limits.",1711.11376v3
+2017-12-07,Flavor Structure of the Cosmic-Ray Electron/Positron Excesses at DAMPE,"The Dark Matter Particle Explorer (DAMPE) satellite detector announced its
+first result for measuring the cosmic-ray electron/positron (CRE) energy
+spectrum up to 4.6TeV, including a tentative peak-like event excess at
+(1.3-1.5)TeV. In this work, we uncover a significant hidden excess in the DAMPE
+CRE spectrum over the energy range (0.6-1.1)TeV, which has a non-peak-like
+structure. We propose a new mechanism to explain this excess by a set of 1.5TeV
+$\mu^\pm$ events with subsequent decays into $e^\pm$ plus neutrinos. For
+explaining this new excess together with the peak excess around 1.4TeV, we
+demonstrate that the {\it flavor structure} of the original lepton final-state
+produced by dark matter (DM) annihilations (or other mechanism) should have a
+composition ratio $N_e : (N_\mu +\frac{1}{6}N_\tau) = 1 : y$, with $y \simeq
+2.6-10.8$. For lepton portal DM models, this puts important constraint on the
+lepton-DM-mediator couplings $\lambda_e : (\lambda_\mu^4 +
+\frac{1}{6}\lambda_\tau^4)^{\frac{1}{4}} = 1 : y^{\frac{1}{4}}$ with a narrow
+range $y^{\frac{1}{4}} \simeq 1.3-1.8$.",1712.02744v3
+2018-01-15,Amplitude- and gas pressure-dependent nonlinear damping of high-Q oscillatory MEMS micro mirrors,"Silicon-based micro-electromechanical systems (MEMS) can be fabricated using
+bulk and surface micromachining technology. A micro mirror designed as an
+oscillatory MEMS constitutes a prominent example. Typically, in order to
+minimize energy consumption, the micro mirror is designed to have high quality
+factors. In addition, a phase-locked loop guarantees resonant actuation despite
+the occurrence of frequency shifts. In these cases, the oscillation amplitude
+of the micro mirror is expected to scale linearly with the actuation input
+power. Here, however, we report on an experimental observation which clearly
+shows an amplitude depletion that is not in accordance with any linear
+behaviour. As a consequence, the actuation forces needed to reach the desired
+oscillation amplitude are by multiples higher than expected. We are able to
+explain the experimental observations accurately by introducing a single
+degree-of-freedom model including an amplitude-dependent nonlinear damping
+term. Remarkably, we find that the nonlinear damping shows a clear gas pressure
+dependency. We investigate the concepts and compare our findings on two
+different micro mirror design layouts.",1801.04758v2
+2018-01-30,Model Based Active Slosh Damping Experiment,"This paper presents a model based experimental investigation to demonstrate
+the usefulness of an active damping strategy to manage fluid sloshing motion in
+spacecraft tanks. The active damping strategy is designed to reduce the
+degrading impact on maneuvering and pointing performance via a force feedback
+strategy. Many problems have been encountered until now, such as instability of
+the closed loop system, excessive consumption in the attitude propellant or
+problems for engine re-ignition in upper stages. Mostly, they have been
+addressed in a passive way via the design of baffles and membranes, which on
+their own have mass and constructive impacts. Active management of propellant
+motion in launchers and satellites has the potential to increase performance on
+various levels. This paper demonstrates active slosh management using force
+feedback for the compensation of the slosh resonances. Force sensors between
+tank and the carrying structure provide information of the fluid motion via the
+reaction force. The control system is designed to generate an appropriate
+acceleration profile that leads to desired attenuation profiles in amplitude,
+frequency and time. Two robust control design methods, one based on $\mu$
+design and the other on parametric structured design based on non-smooth
+optimization of the worst-case $H_{\infty}$ norm, are applied. The controller
+is first tested with a computational fluid dynamics simulation in the loop.
+Finally a water tank mounted on a Hexapod with up to $1100$ liter is used to
+evaluate the control performance. The paper illustrates that is possible to
+actively influence sloshing via closed loop.",1801.10017v1
+2018-03-22,Propagative and diffusive regimes of acoustic damping in bulk amorphous material,"In amorphous solids, a non-negligible part of thermal conductivity results
+from phonon scattering on the structural disorder. The conversion of acoustic
+energy into thermal energy is often measured by the Dynamical Structure Factor
+(DSF) thanks to inelastic neutron or X-Ray scattering. The DSF is used to
+quantify the dispersion relation of phonons, together with their damping.
+However, the connection of the dynamical structure factor with dynamical
+attenuation of wave packets in glasses is still a matter of debate. We focus
+here on the analysis of wave packets propagation in numerical models of
+amorphous silicon. We show that the DHO fits (Damped Harmonic Oscillator model)
+of the dynamical structure factors give a good estimate of the wave packets
+mean-free path, only below the Ioffe-Regel limit. Above the Ioffe-Regel limit
+and below the mobility edge, a pure diffusive regime without a definite mean
+free path is observed. The high-frequency mobility edge is characteristic of a
+transition to localized vibrations. Below the Ioffe-Regel criterion, a mixed
+regime is evidenced at intermediate frequencies, with a coexistence of
+propagative and diffusive wave fronts. The transition between these different
+regimes is analyzed in details and reveals a complex dynamics for energy
+transportation, thus raising the question of the correct modeling of thermal
+transport in amorphous materials.",1803.08594v1
+2018-04-11,Axial quasi-normal modes of neutron stars in $R^2$ gravity,"In the present paper the axial quasi-normal modes of neutron stars in $f(R)$
+gravity are examined using a large set of equations of state. The numerical
+calculations are made using two different approaches -- performing time
+evolution of the perturbation equations and solving the time-independent
+representation of the equations as a boundary value problem. According to the
+results the mode frequencies and the damping times decrease with the increase
+of the free parameter of the theory in comparison to the pure general
+relativistic case. While the frequencies deviate significantly from Einstein's
+theory for all realistic neutron star masses (say above $1M_\odot$), the
+damping times reach non-negligible differences only for the more massive
+models. We have constructed as well universal (equation of state independent)
+gravitational wave asteroseismology relations involving the frequencies and the
+damping times. It turns out that the equation of state independence is
+preserved using the same normalization as in pure general relativity and the
+qualitative differences of the phenomenological relations with respect to
+Einstein's theory of gravity can be large for large values of the free
+parameter in $f(R)$ gravity.",1804.04060v1
+2018-05-10,Dust modification of the plasma conductivity in the mesosphere,"Relative transverse drift (with respect to the ambient magnetic field)
+between the weakly magnetized electrons and the unmagnetized ions at the lower
+altitude (80 km) and between the weakly magnetized ions and unmagnetized dust
+at the higher altitude (90 km) gives rise to the finite Hall conductivity in
+the Earth's mesosphere. If, on the other hand, the number of free electrons is
+sparse in the mesosphere and most of the negative charge resides on the weakly
+magnetized, fine, nanometre sized dust powder and positive charge on the more
+massive, micron sized, unmagnetized dust, the sign of the Hall conductivity due
+to their relative transverse drift will be opposite to the previous case. Thus
+the sign of the Hall effect not only depends on the direction of the local
+magnetic field but also on the nature of the charge carrier in the partially
+ionized dusty medium.
+  As the Hall and the Ohm diffusion are comparable below 80 km, the low
+frequency long wavelength waves will be damped at this altitude with the
+damping rate typically of the order of few minutes. Therefore, the ultra--low
+frequency magnetohydrodynamic waves can not originate below 80 km in the
+mesosphere. However, above 80 km since Hall effect dominates Ohm diffusion the
+mesosphere can host the ultra--low frequency waves which can propagate across
+the ionosphere with little or, no damping.",1805.03799v1
+2018-05-19,Migration of Planets Into and Out of Mean Motion Resonances in Protoplanetary Discs: Overstability of Capture and Nonlinear Eccentricity Damping,"A number of multiplanet systems are observed to contain planets very close to
+mean motion resonances, although there is no significant pileup of precise
+resonance pairs. We present theoretical and numerical studies on the outcome of
+capture into first-order mean motion resonances (MMRs) using a parametrized
+planet migration model that takes into account nonlinear eccentricity damping
+due to planet-disk interaction. This parametrization is based on numerical
+hydrodynamical simulations and is more realistic than the simple linear
+parametrization widely used in previous analytic studies. We find that
+nonlinear eccentricity damping can significantly influence the stability and
+outcome of resonance capture. In particular, the equilibrium eccentricity of
+the planet captured into MMRs become larger, and the captured MMR state tends
+to be more stable compared to the prediction based on the simple migration
+model. In addition, when the migration is sufficiently fast or/and the planet
+mass ratio is sufficiently small, we observe a novel phenomenon of eccentricity
+overshoot, where the planet's eccentricity becomes very large before settling
+down to the lower equilibrium value. This can lead to the ejection of the
+smaller planet if its eccentricity approaches unity during the overshoot. This
+may help explain the lack of low-mass planet companion of hot Jupiters when
+compared to warm Jupiters.",1805.07501v1
+2018-06-04,Density Waves and the Viscous Overstability in Saturn's Rings,"This paper addresses resonantly forced spiral density waves in a dense
+planetary ring which is close to the threshold for viscous overstability. We
+solve numerically the hydrodynamical equations for a dense, axisymmetric thin
+disk in the vicinity of an inner Lindblad resonance with a perturbing
+satellite. The spiral shape of a density wave is taken into account through a
+suitable approximation of the advective terms arising from the fluid orbital
+motion. This paper is a first attempt to model the co-existence of resonantly
+forced density waves and short-scale axisymmetric overstable wavetrains in
+Saturn's rings by conducting large-scale hydrodynamical integrations. These
+integrations reveal that the two wave types undergo complex interactions, not
+taken into account in existing models for the damping of density waves. In
+particular it is found that, depending on the relative magnitude of both wave
+types, the presence of viscous overstability can lead to a damping of an
+unstable density wave and vice versa. The damping of viscous overstability by a
+density wave is investigated further by employing a simplified model of an
+axisymmetric ring perturbed by a nearby Lindblad resonance. A linear
+hydrodynamic stability analysis as well as local N-body simulations of this
+model system are performed and support the results of our large-scale
+hydrodynamical integrations.",1806.01211v3
+2018-07-02,Thermoplasmonic behavior of semiconductor nanoparticles: A comparison with metals,"A number of applications in nanoplasmonics utilize noble metals, gold (Au)
+and silver (Ag), as the materials of choice. However, these materials suffer
+from problems of poor thermal and chemical stability accompanied by significant
+dissipative losses under high-temperature conditions. In this regard,
+semiconductor nanoparticles have attracted attention with their promising
+characteristics of highly tunable plasmonic resonances, low ohmic losses and
+greater thermochemical stability. Here, we investigate the size-dependent
+thermoplasmonic properties of semiconducting silicon and gallium arsenide
+nanoparticles to compare them with metallic Au nanoparticles using Mie theory.
+To this end, we employ experimentally estimated models of dielectric
+permittivity in our computations. Among the various permittivity models for Au,
+we further compare the Drude-Lorentz (DL) and the Drude and critical points
+(DCP) models. Results show a redshift in the scattering and absorption
+resonances for the DL model while the DCP model presents a blueshift. The
+dissipative damping in the semiconductor nanoparticles is strongest for the
+sharp electric octupole resonances followed by the quadrupole and dipole modes.
+However, a reverse order with strongest values for the broad dipole resonance
+is observed for the Au nanoparticles. A massive Drude broadening contributes
+strongly to the damping of resonances in Au nanoparticles at elevated
+temperatures. In contrast, the semiconductor nanoparticles do not exhibit any
+significant deterioration in their scattering and absorption resonances at high
+temperatures. In combination with low dissipative damping, this makes the
+semiconductor nanoparticles better suited for high-temperature applications in
+nanoplasmonics wherein the noble metals suffer from excessive heating.",1807.00881v1
+2018-08-03,Witnessing galaxy assembly at the edge of the reionization epoch,"We report the discovery of Serenity-18, a galaxy at z=5.939 for which we
+could measure the content of molecular gas, M(H_2)~ 5 x10^9 M_sun, traced by
+the CO(6-5) emission, together with the metal-poor ([Fe/H]=-3.08 +- 0.12,
+[Si/H]=-2.86 +- 0.14) gas clump/filament which is possibly feeding its growth.
+The galaxy has an estimated star formation rate of ~100 M_sun yr^{-1}, implying
+that it is a typical main sequence galaxy at these redshifts. The metal-poor
+gas is detected through a damped Lyman-alpha absorber (DLA) observed at a
+spatial separation of 40 kpc and at the same redshift of Serenity-18, along the
+line of sight to the quasar SDSS J2310+1855 (z_em = 6.0025). The chemical
+abundances measured for the damped Lyman-alpha system are in very good
+agreement with those measured for other DLAs discovered at similar redshifts,
+indicating an enrichment due to massive PopII stars. The galaxy/Damped system
+we discovered is a direct observational evidence of the assembly of a galaxy at
+the edge of the reionization epoch.",1808.01146v2
+2018-08-13,Fluidization of collisionless plasma turbulence,"In a collisionless, magnetized plasma, particles may stream freely along
+magnetic-field lines, leading to phase ""mixing"" of their distribution function
+and consequently to smoothing out of any ""compressive"" fluctuations (of
+density, pressure, etc.,). This rapid mixing underlies Landau damping of these
+fluctuations in a quiescent plasma-one of the most fundamental physical
+phenomena that make plasma different from a conventional fluid. Nevertheless,
+broad power-law spectra of compressive fluctuations are observed in turbulent
+astrophysical plasmas (most vividly, in the solar wind) under conditions
+conducive to strong Landau damping. Elsewhere in nature, such spectra are
+normally associated with fluid turbulence, where energy cannot be dissipated in
+the inertial scale range and is therefore cascaded from large scales to small.
+By direct numerical simulations and theoretical arguments, it is shown here
+that turbulence of compressive fluctuations in collisionless plasmas strongly
+resembles one in a collisional fluid and does have broad power-law spectra.
+This ""fluidization"" of collisionless plasmas occurs because phase mixing is
+strongly suppressed on average by ""stochastic echoes"", arising due to nonlinear
+advection of the particle distribution by turbulent motions. Besides resolving
+the long-standing puzzle of observed compressive fluctuations in the solar
+wind, our results suggest a conceptual shift for understanding kinetic plasma
+turbulence generally: rather than being a system where Landau damping plays the
+role of dissipation, a collisionless plasma is effectively dissipationless
+except at very small scales. The universality of ""fluid"" turbulence physics is
+thus reaffirmed even for a kinetic, collisionless system.",1808.04284v1
+2018-08-15,Neural Material: Learning Elastic Constitutive Material and Damping Models from Sparse Data,"The accuracy and fidelity of deformation simulations are highly dependent
+upon the underlying constitutive material model. Commonly used linear or
+nonlinear constitutive material models only cover a tiny part of possible
+material behavior. In this work we propose a unified framework for modeling
+deformable material. The key idea is to use a neural network to correct a
+nominal model of the elastic and damping properties of the object. The neural
+network encapsulates a complex function that is hard to explicitly model. It
+injects force corrections that help the forward simulation to more accurately
+predict the true behavior of a given soft object, which includes non-linear
+elastic forces and damping. Attempting to satisfy the requirement from real
+material interference and animation design scenarios, we learn material models
+from examples of dynamic behavior of a deformable object's surface. The
+challenge is that such data is sparse as it is consistently given only on part
+of the surface. Sparse reduced space-time optimization is employed to gradually
+generate increasingly accurate training data, which further refines and
+enhances the neural network. We evaluate our choice of network architecture and
+show evidence that the modest amount of training data we use is suitable for
+the problem tackled. Our method is demonstrated with a set of synthetic
+examples.",1808.04931v1
+2018-09-06,Forming Gliese 876 Through Smooth Disk Migration,"We run a suite of dissipative N-body simulations to determine which regions
+of phase space for smooth disk migration are consistent with the GJ876 system,
+an M-dwarf hosting three planets orbiting in a chaotic 4:2:1 Laplace resonance.
+We adopt adaptive mesh refinement (AMR) methods which are commonly used in
+hydrodynamical simulations to efficiently explore the parameter space defined
+by the semi-major axis and eccentricity damping timescales. We find that there
+is a large region of phase space which produces systems in the chaotic Laplace
+resonance and a smaller region consistent with the observed eccentricities and
+libration amplitudes for the resonant angles. Under the assumptions of Type I
+migration for the outer planet, we translate these damping timescales into
+constraints on the protoplanetary disk surface density and thickness. When we
+strongly (weakly) damp the eccentricities of the inner two Laplace planets,
+these timescales correspond to disk surface densities around ten thousand (a
+few hundred) grams per square centimeter and disk aspect ratios between 1-10%.
+Additionally, smooth migration produces systems with a range of chaotic
+timescales, from decades and centuries to upwards of thousands of years. In
+agreement with previous studies, the less chaotic regions of phase space
+coincide with the system being in a low energy double apsidal corotation
+resonance. Our detailed modeling of multi-planetary systems coupled with our
+AMR exploration method enhances our ability to map out the parameter space of
+planet formation models, and is well suited to study other resonant chain
+systems such as Trappist-1, Kepler-60, and others.",1809.02200v2
+2018-09-15,New closures for more precise modeling of Landau damping in the fluid framework,"Incorporation of kinetic effects such as Landau damping into a fluid
+framework was pioneered by Hammett and Perkins PRL 1990, by obtaining closures
+of the fluid hierarchy, where the gyrotropic heat flux fluctuations or the
+deviation of the 4th-order gyrotropic fluid moment, are expressed through
+lower-order fluid moments. To obtain a closure of a fluid model expanded around
+a bi-Maxwellian distribution function, the usual plasma dispersion function
+$Z(\zeta)$ that appears in kinetic theory or the associated plasma response
+function $R(\zeta)=1 + \zeta Z(\zeta)$, have to be approximated with a suitable
+Pad\'e approximant in such a way, that the closure is valid for all $\zeta$
+values. Such closures are rare, and the original closures of Hammett and
+Perkins are often employed. Here we present a complete mapping of all plausible
+Landau fluid closures that can be constructed at the level of 4th-order moments
+in the gyrotropic limit and we identify the most precise closures. Furthermore,
+by considering 1D closures at higher-order moments, we show that it is possible
+to reproduce linear Landau damping in the fluid framework to any desired
+precision, thus showing convergence of the fluid and collisionless kinetic
+descriptions.",1809.05718v1
+2018-10-04,Sub-photospheric turbulence as a heating mechanism in gamma-ray bursts,"We examine the possible role of turbulence in feeding the emission of
+gamma-ray bursts (GRBs). Turbulence may develop in a GRB jet as the result of
+hydrodynamic or current-driven instabilities. The jet carries dense radiation
+and the turbulence cascade can be damped by Compton drag, passing kinetic fluid
+energy to photons through scattering. We identify two regimes of turbulence
+dissipation: (1) ""Viscous"" - the turbulence cascade is Compton damped on a
+scale $\ell_{\rm damp}$ greater than the photon mean free path $\ell_\star$.
+Then turbulence energy is passed to photons via bulk Comptonization by smooth
+shear flows on scale $\ell_\star<\ell_{\rm damp}$. (2) ""Collisionless"" - the
+cascade avoids Compton damping and extends to microscopic plasma scales much
+smaller than $\ell_\star$. The collisionless dissipation energizes plasma
+particles, which radiate the received energy; how the dissipated power is
+partitioned between particles needs further investigation with kinetic
+simulations. We show that the dissipation regime switches from viscous to
+collisionless during the jet expansion, at a critical value of the jet optical
+depth which depends on the amplitude of turbulence. Turbulent GRB jets are
+expected to emit nonthermal photospheric radiation. Our analysis also suggests
+revisions of turbulent Comptonization in black hole accretion disks discussed
+in previous works.",1810.02228v1
+2018-10-15,Zombie Vortex Instability. III. Persistence with Nonuniform Stratification and Radiative Damping,"The Zombie Vortex Instability (ZVI) occurs in the dead zones of
+protoplanetary disks (PPDs) where perturbations excite baroclinic critical
+layers, generating ""zombie"" vortices and turbulence. In this work, we
+investigate ZVI with nonuniform vertical stratification; while ZVI is triggered
+in the stratified regions away from the midplane, the subsequent turbulence
+propagates into and fills the midplane. ZVI turbulence alters the background
+Keplerian shear flow, creating a steady-state zonal flow. Intermittency is
+observed, where the flow cycles through near-laminar phases of zonal flow
+punctuated by chaotic bursts of new vortices. ZVI persists in the presence of
+radiative damping, as long as the thermal relaxation timescale is more than a
+few orbital periods. We refute the premature claim by Lesur & Latter (2016)
+that radiative damping inhibits ZVI for disk radii r>0.3 au. Their conclusions
+were based on unrealistically short cooling times using opacities with
+virtually no grain growth. We explore different grain growth and vertical
+settling scenarios, and find that the gas and dust in off-midplane regions are
+not necessarily in local thermodynamic equilibrium (LTE) with each other. In
+such cases, thermal relaxation timescales can be orders of magnitude longer
+than the optically thin cooling times assuming LTE because of the finite time
+for energy to be exchanged between gas and dust grains via collisions. With
+minimal amounts of grain growth and dust settling, the off-midplane regions of
+disks are susceptible to ZVI and much of the planet-forming regions can be
+filled with zombie vortices and turbulence.",1810.06588v1
+2018-09-21,High performance passive vibration isolation system for optical tables using six-degree-of-freedom viscous damping combined with steel springs,"Mechanical vibrations in buildings are ubiquitous. Such vibrations limit the
+performance of sensitive instruments used, for example, for high-precision
+manufacturing, nanofabrication, metrology, medical systems, or microscopy. For
+improved precision, instruments and optical tables need to be isolated from
+mechanical vibrations. However, common active or passive vibration isolation
+systems often perform poorly when low-frequency vibration isolation is required
+or are expensive. Furthermore, a simple solution such as suspension from common
+bungee cords may require high ceilings. Here we developed a vibration isolation
+system that uses steel springs to suspend an optical table from a common-height
+ceiling. The system was designed for a fundamental resonance frequency of 0.5
+Hz. Resonances and vibrations were efficiently damped in all translational and
+rotational degrees of freedom of the optical table by spheres, which were
+mounted underneath the table and immersed in a highly viscous silicone oil. Our
+low-cost, passive system outperformed several state-of-the-art passive and
+active systems in particular in the frequency range between 1-10 Hz. We
+attribute this performance to a minimal coupling between the degrees of freedom
+and the truly three dimensional viscous damping combined with a nonlinear
+hydrodynamic finite-size effect. Furthermore, the system can be adapted to
+different loads, resonance frequencies, and dimensions. In the long term, the
+excellent performance of the system will allow high-precision measurements for
+many different instruments.",1810.06641v4
+2018-10-23,Calibration of the DAMPE Plastic Scintillator Detector and its on-orbit performance,"DArk Matter Particle Explorer (DAMPE) is a space-borne apparatus for
+detecting the high-energy cosmic-rays like electrons, $\gamma$-rays, protons
+and heavy-ions. Plastic Scintillator Detector (PSD) is the top-most
+sub-detector of the DAMPE. The PSD is designed to measure the charge of
+incident high-energy particles and it also serves as a veto detector for
+discriminating $\gamma$-rays from charged particles. In this paper, PSD
+on-orbit calibration procedure is described, which includes five steps of
+pedestal, dynode correlation, response to minimum-ionizing particles (MIPs),
+light attenuation function and energy reconstruction. A method for
+reconstructing the charge of incident high energy cosmic-ray particles is
+introduced. The detection efficiency of each PSD strip is verified to be above
+99.5%, the total efficiency of the PSD for charged particles is above 99.99%.",1810.09901v1
+2018-10-25,Charge Measurement of Cosmic Ray Nuclei with the Plastic Scintillator Detector of DAMPE,"One of the main purposes of the DArk Matter Particle Explorer (DAMPE) is to
+measure the cosmic ray nuclei up to several tens of TeV or beyond, whose origin
+and propagation remains a hot topic in astrophysics. The Plastic Scintillator
+Detector (PSD) on top of DAMPE is designed to measure the charges of cosmic ray
+nuclei from H to Fe and serves as a veto detector for discriminating gamma-rays
+from charged particles. We propose in this paper a charge reconstruction
+procedure to optimize the PSD performance in charge measurement. Essentials of
+our approach, including track finding, alignment of PSD, light attenuation
+correction, quenching and equalization correction are described detailedly in
+this paper after a brief description of the structure and operational principle
+of the PSD. Our results show that the PSD works very well and almost all the
+elements in cosmic rays from H to Fe are clearly identified in the charge
+spectrum.",1810.10784v1
+2018-11-14,Anderson-Bogoliubov and Carlson-Goldman modes in counterflow superconductors: Case study of a double monolayer graphene,"The impact of electron-hole pairing on the spectrum of plasma excitations in
+double layer systems is investigated. The theory is developed with reference to
+a double monolayer graphene. Taking into account the coupling of scalar
+potential oscillations with oscillations of the order parameter $\Delta$, we
+show that the spectrum of antisymmetric (acoustic) plasma excitations contains
+two modes: a weakly damped mode below the gap $2\Delta$ and a strongly damped
+mode above the gap. The lower mode can be interpreted as an analog of the
+Carlson-Goldman mode. This mode has an acoustic dispersion relation at small
+wave vectors and it saturates at the level $2\Delta$ at large wave vectors. Its
+velocity is larger than the velocity of the Anderson-Bogoliubov mode
+$v_{AB}=v_F$/$\sqrt{2}$, and it can be smaller than the Fermi velocity $v_F$.
+The damping rate of this mode strongly increases under increase of temperature.
+Out-of-phase oscillations of two order parameters in two spin subsystems are
+also considered. This part of the spectrum contains two more modes. One of them
+is interpreted as an analog of the Anderson-Bogoliubov (phase) mode and the
+other, as an analog of the Schmid (amplitude) mode. With minor modifications
+the theory can be extended to describe collective modes in a double bilayer
+graphene as well.",1811.05899v3
+2018-12-07,Magnetic Braking and Damping of Differential Rotation in Massive Stars,"Fragmentation of highly differentially rotating massive stars that undergo
+collapse has been suggested as a possible channel for binary black hole
+formation. Such a scenario could explain the formation of the new population of
+massive black holes detected by the LIGO/VIRGO gravitational wave laser
+interferometers. We probe that scenario by performing general relativistic
+magnetohydrodynamic simulations of differentially rotating massive stars
+supported by thermal radiation pressure plus a gas pressure perturbation. The
+stars are initially threaded by a dynamically weak, poloidal magnetic field
+confined to the stellar interior. We find that magnetic braking and turbulent
+viscous damping via magnetic winding and the magnetorotational instability in
+the bulk of the star redistribute angular momentum, damp differential rotation
+and induce the formation of a massive and nearly uniformly rotating inner core
+surrounded by a Keplerian envelope. The core + disk configuration evolves on a
+secular timescale and remains in quasi-stationary equilibrium until the
+termination of our simulations. Our results suggest that the high degree of
+differential rotation required for $m=2$ seed density perturbations to trigger
+gas fragmentation and binary black hole formation is likely to be suppressed
+during the normal lifetime of the star prior to evolving to the point of
+dynamical instability to collapse. Other cataclysmic events, such as stellar
+mergers leading to collapse, may therefore be necessary to reestablish
+sufficient differential rotation and density perturbations to drive
+nonaxisymmetric modes leading to binary black hole formation.",1812.03176v3
+2018-12-18,Inferring physical parameters in solar prominence threads,"High resolution observations have permitted to resolve the solar
+prominences/filaments as sets of threads/fibrils. However, the values of the
+physical parameters of these threads and their structuring remain poorly
+constrained. We use prominence seismology techniques to analyse transverse
+oscillations in threads through the comparison between magnetohydrodynamic
+(MHD) models and observations. We apply Bayesian methods to obtain two
+different types of information. We first infer the marginal posterior
+distribution of physical parameters, such as the magnetic field strength or the
+length of the thread, when a totally filled tube, a partially filled tube, and
+three damping models (resonant absorption in the Alfv\'en continuum, resonant
+absorption in the slow continuum, and Cowling's diffusion) are considered as
+certain. Then, we compare the relative plausibility between alternative MHD
+models by computing the Bayes factors. Well constrained probability density
+distributions can be obtained for the magnetic field strength, the length of
+the thread, the density contrast, and parameters associated to damping models.
+When comparing the damping models of resonant absorption in the Alfv\'en
+continuum, resonant absorption in the slow continuum and Cowling's diffusion
+due to partial ionisation of prominence plasma, the resonant absorption in the
+Alfv\'en continuum is the most plausible mechanism in explaining the existing
+observations. Relations between periods of fundamental and first overtone kink
+modes with values around 1 are better explained by expressions of the period
+ratio in the long thread approximation, while the rest of the values are more
+probable in the short thread limit for the period ratio. Our results show that
+Bayesian analysis offers valuable methods for performing parameter inference
+and model comparison in the context of prominence seismology.",1812.07262v1
+2019-01-07,Abnormal anti-crossing effect in photon-magnon coupling,"We report the experimental demonstration of an abnormal, opposite
+anti-crossing effect in a photon-magnon-coupled system that consists of an
+Yttrium Iron Garnet film and an inverted pattern of split-ring resonator
+structure (noted as ISRR) in a planar geometry. It is found that the normal
+shape of anti-crossing dispersion typically observed in photon-magnon coupling
+is changed to its opposite anti-crossing shape just by changing the
+position/orientation of the ISRR's split gap with respect to the microstrip
+line axis along which ac microwave currents are applied. Characteristic
+features of the opposite anti-crossing dispersion and its linewidth evolution
+are analyzed with the help of analytical derivations based on electromagnetic
+interactions. The observed opposite anti-crossing dispersion is ascribed to the
+compensation of both intrinsic damping and coupling-induced damping in the
+magnon modes. This compensation is achievable by controlling the relative
+strength and phase of oscillating magnetic fields generated from the ISRR's
+split gap and the microstrip feeding line. The position/orientation of an
+ISRR's split gap provides a robust means of controlling the dispersion shape of
+anti-crossing and its damping in a photon-magnon coupling, thereby offering
+more opportunity for advanced designs of microwave devices.",1901.01729v2
+2019-01-24,A compact actively damped vibration isolation platform for optical experiments in ultra-high vacuum,"We present a tabletop six-axis vibration isolation system, compatible with
+Ultra-High Vacuum (UHV), which is actively damped and provides 25 dB of
+isolation at 10 Hz and 65 dB at 100 Hz. While this isolation platform has been
+primarily designed to support optics in the Laser Interferometer
+Gravitational-Wave Observatory (LIGO) detectors, it is suitable for a variety
+of applications. The system has been engineered to facilitate the construction
+and assembly process, while minimizing cost. The platform provides passive
+isolation for six degrees of freedom using a combination of vertical springs
+and horizontal pendula. It is instrumented with voice-coil actuators and
+optical shadow sensors to damp the resonances. All materials are compatible
+with stringent vacuum requirements. Thanks to its architecture, the system's
+footprint can be adapted to meet spatial requirements, while maximizing the
+dimensions of the optical table. Three units are currently operating for LIGO.
+We present the design of the system, controls principle, and experimental
+results.",1901.09666v2
+2019-01-28,Strong damping-like spin-orbit torque and tunable Dzyaloshinskii-Moriya interaction generated by low-resistivity Pd$_{1-x}$Pt$_x$ alloys,"Despite their great promise for providing a pathway for very efficient and
+fast manipulation of magnetization at the nanoscale, spin-orbit torque (SOT)
+operations are currently energy inefficient due to a low damping-like SOT
+efficiency per unit current bias, and/or the very high resistivity of the spin
+Hall materials. Here, we report an advantageous spin Hall material, Pd1-xPtx,
+which combines a low resistivity with a giant spin Hall effect as evidenced
+through the use of three independent SOT ferromagnetic detectors. The optimal
+Pd0.25Pt0.75 alloy has a giant internal spin Hall ratio of >0.47 (damping-like
+SOT efficiency of ~ 0.26 for all three ferromagnets) and a low resistivity of
+~57.5 {\mu}{\Omega} cm at 4 nm thickness. Moreover, we find the
+Dzyaloshinskii-Moriya interaction (DMI), the key ingredient for the
+manipulation of chiral spin arrangements (e.g. magnetic skyrmions and chiral
+domain walls), is considerably strong at the Pd1-xPtx/Fe0.6Co0.2B0.2 interface
+when compared to that at Ta/Fe0.6Co0.2B0.2 or W/Fe0.6Co0.2B0.2 interfaces and
+can be tuned by a factor of 5 through control of the interfacial spin-orbital
+coupling via the heavy metal composition. This work establishes a very
+effective spin current generator that combines a notably high energy efficiency
+with a very strong and tunable DMI for advanced chiral spintronics and spin
+torque applications.",1901.09954v1
+2019-02-13,Two-mediator dark matter models and cosmic electron excess,"The cosmic electron energy spectrum recently observed by the DAMPE experiment
+exhibits two interesting features, including a break around 0.9 TeV and a sharp
+resonance near 1.4 TeV. In this analysis, we propose a dark matter explanation
+to both exotic features seen by DAMPE. In our model, dark matter annihilates in
+the galaxy via two different channels that lead to both a narrow resonance
+spectrum near 1.4 TeV and electron excess events over an extended energy range
+thus generating the break structure around TeV. The two annihilation channels
+are mediated by two gauge bosons that interact both with dark matter and with
+the standard model fermions. Dark matter annihilations through the s-channel
+process mediated by the heavier boson produce monoenergetic electron-positron
+pairs leading to the resonance excess. The lighter boson has a mass smaller
+than the dark matter such that they can be on-shell produced in dark matter
+annihilations in the galaxy; the lighter bosons in the final state subsequently
+decay to generate the extended excess events due to the smeared electron energy
+spectrum in this process. We further analyze constraints from various
+experiments, including HESS, Fermi, AMS, and LHC, to the parameter space of the
+model where both excess events can be accounted for. In order to interpret the
+two new features in the DAMPE data, dark matter annihilation cross sections in
+the current galaxy are typically much larger than the canonical thermal cross
+section needed for the correct dark matter relic abundance. This discrepancy,
+however, is remedied by the nonperturbative Sommerfeld enhancement because of
+the existence of a lighter mediator in the model.",1902.04916v1
+2019-02-18,Coherent control of magnon radiative damping with local photon states,"The collective excitation of ordered spins, known as spin waves or magnons,
+can in principle radiate by emitting travelling photons to an open system when
+decaying to the ground state. However, in contrast to the electric dipoles,
+magnetic dipoles contributed by magnons are more isolated from electromagnetic
+environment with negligible radiation in the vacuum, limiting their application
+in coherent communication by photons. Recently, strong interaction between
+cavity standing-wave photons and magnons has been reported, indicating the
+possible manipulation of magnon radiation via tailoring photon states. Here,
+with loading an yttrium iron garnet sphere in a one-dimensional circular
+waveguide cavity in the presence of both travelling and standing photon modes,
+we demonstrate an efficient photon emissions from magnon and a significant
+magnon radiative damping with radiation rate found to be proportional to the
+local density of states (LDOS) of photon. By modulating the LDOS including its
+magnitude and/or polarization, we can flexibly tune the photon emission and
+magnon radiative damping on demand. Our findings provide a general way in
+manipulating photon emission from magnon radiation for harnessing energy and
+angular momentum generation, transfer and storage modulated by magnon in the
+cavity and waveguide electrodynamics.",1902.06795v2
+2019-03-04,Quantum speed limit time for the damped Jaynes-Cummings and Ohmic-like dephasing models in Schwarzschild spacetime,"Quantum theory sets the bound on the minimal evolution time between initial
+and final states of the quantum system. This minimal evolution time can be used
+to specify the maximal speed of the evolution in open and closed quantum
+systems. Quantum speed limit is one of the interesting issue in the theory of
+open quantum systems. One may investigate the influence of the relativistic
+effect on the quantum speed limit time. When several observers are placed in
+different inertial or non-inertial frames, or in Schwarzschild space-time, the
+relativistic effect should be taken into account. In this work, the quantum
+speed limit time in Schwarzschild space-time will be studied for two various
+model consist of damped Jaynes-Cummings and Ohmic-like dephasing. First, it
+will be observed that how quantum coherence is affected by Hawking radiation.
+According to the dependence of quantum speed limit time on quantum coherence
+and the dependence of quantum coherence on relative distance of quantum system
+to event horizon $R_{0}$, it will be represented that the quantum speed limit
+time in Schwarzschild space-time is decreased by increasing $R_{0}$ for damped
+Jaynes-Cummings model and conversely, It is increased by increasing $R_{0}$ for
+Ohmic-like dephasing model .",1903.01230v2
+2019-03-25,Stabilised Asynchronous Fast Adaptive Composite Multigrid using Additive Damping,"Multigrid solvers face multiple challenges on parallel computers. Two
+fundamental ones read as follows: Multiplicative solvers issue coarse grid
+solves which exhibit low concurrency and many multigrid implementations suffer
+from an expensive coarse grid identification phase plus adaptive mesh
+refinement overhead. We propose a new additive multigrid variant for
+spacetrees, i.e. meshes as they are constructed from octrees and quadtrees: It
+is an additive scheme, i.e. all multigrid resolution levels are updated
+concurrently. This ensures a high concurrency level, while the transfer
+operators between the mesh levels can still be constructed algebraically. The
+novel flavour of the additive scheme is an augmentation of the solver with an
+additive, auxiliary damping parameter per grid level per vertex that is in turn
+constructed through the next coarser level---an idea which utilises smoothed
+aggregation principles or the motivation behind AFACx: Per level, we solve an
+additional equation whose purpose is to damp too aggressive solution updates
+per vertex which would otherwise, in combination with all the other levels,
+yield an overcorrection and, eventually, oscillations. This additional equation
+is constructed additively as well, i.e. is once more solved concurrently to all
+other equations. This yields improved stability, closer to what is seen with
+multiplicative schemes, while pipelining techniques help us to write down the
+additive solver with single-touch semantics for dynamically adaptive meshes.",1903.10367v3
+2019-04-04,The DAMPE excess and gamma-ray constraints,"The direct measurements of the cosmic electron-positron spectrum around 1 TeV
+made by DAMPE have induced many theoretical speculations about possible
+excesses in the data above the standard astrophysical predictions that might
+have the dark matter (DM) origin. These attempts mainly fall into two
+categories: i) DM annihilation (or decay) in the Galactic halo producing the
+broad spectrum excess; ii) DM annihilation in the nearby compact subhalo
+producing the sharp peak at 1.4 TeV. We investigate the gamma-ray emission
+accompanying $e^+e^-$ production in DM annihilation, as well as various
+theoretical means to suppress the prompt radiation, such as specific
+interaction vertices or multi-cascade modes, and conclude that these attempts
+are in tension with various gamma-ray observations. We show that the DM
+explanations of the broad spectrum excess tend to contradict the diffuse
+isotropic gamma-ray background (IGRB), measured by Fermi-LAT, while the nearby
+subhalo scenario is constrained by nonobservation in the surveys, performed by
+Fermi-LAT, MAGIC and HESS. We also briefly review other types of gamma-ray
+constraints, which seem to rule out the DM interpretations of the DAMPE broad
+spectrum excess as well.",1904.02456v2
+2019-04-10,Stochastic nonlinear wave dynamics on compact surfaces,"We study the Cauchy problem for the nonlinear wave equations (NLW) with
+random data and/or stochastic forcing on a two-dimensional compact Riemannian
+manifold without boundary. (i) We first study the defocusing stochastic damped
+NLW driven by additive space-time white-noise, and with initial data
+distributed according to the Gibbs measure. By introducing a suitable
+space-dependent renormalization, we prove local well-posedness of the
+renormalized equation. Bourgain's invariant measure argument then allows us to
+establish almost sure global well-posedness and invariance of the Gibbs measure
+for the renormalized stochastic damped NLW. (ii) Similarly, we study the random
+data defocusing NLW (without stochastic forcing), and establish the same
+results as in the previous setting. (iii) Lastly, we study the stochastic NLW
+without damping. By introducing a space-time dependent renormalization, we
+prove its local well-posedness with deterministic initial data in all
+subcritical spaces.
+  These results extend the corresponding recent results on the two-dimensional
+torus obtained by (i) Gubinelli-Koch-Oh-Tolomeo (2018), (ii) Oh-Thomann (2017),
+and (iii) Gubinelli-Koch-Oh (2018), to a general class of compact manifolds.
+The main ingredient is the Green's function estimate for the Laplace-Beltrami
+operator in this setting to study regularity properties of stochastic terms
+appearing in each of the problems.",1904.05277v3
+2019-04-30,Damping rates and frequency corrections of Kepler LEGACY stars,"Linear damping rates and modal frequency corrections of radial oscillation
+modes in selected LEGACY main-sequence stars are estimated by means of a
+nonadiabatic stability analysis. The selected stellar sample covers stars
+observed by Kepler with a large range of surface temperatures and surface
+gravities. A nonlocal, time-dependent convection model is perturbed to assess
+stability against pulsation modes. The mixing-length parameter is calibrated to
+the surface-convection-zone depth of a stellar model obtained from fitting
+adiabatic frequencies to the LEGACY observations, and two of the nonlocal
+convection parameters are calibrated to the corresponding LEGACY linewidth
+measurements. The remaining nonlocal convection parameters in the 1D
+calculations are calibrated so as to reproduce profiles of turbulent pressure
+and of the anisotropy of the turbulent velocity field of corresponding 3D
+hydrodynamical simulations. The atmospheric structure in the 1D stability
+analysis adopts a temperature-optical-depth relation derived from 3D
+hydrodynamical simulations. Despite the small number of parameters to adjust,
+we find good agreement with detailed shapes of both turbulent pressure profiles
+and anisotropy profiles with depth, and with damping rates as a function of
+frequency. Furthermore, we find the absolute modal frequency corrections,
+relative to a standard adiabatic pulsation calculation, to increase with
+surface temperature and surface gravity.",1904.13170v1
+2019-05-09,An excess of excesses examined via dark matter radio emissions from galaxies,"Cosmic-ray and gamma-ray observations have yielded several notable excesses
+that often lend themselves to explanation by various dark matter
+annihilation/decay models. In particular, the AMS-02 anti-proton and positron
+excesses have continued to grow more robust with the collection of more data.
+This is supplemented by gamma-ray excesses in the Galactic Centre and a
+high-energy break in spectrum of electron/positron cosmic rays seen by DAMPE.
+In this work we carefully model the magnetic field environments of M31 and M33
+and use this to estimate expected synchrotron emissions from electrons produced
+via dark matter annihilation. By comparing this to available radio data we
+review simplifying assumptions used previously for dark matter hunting in these
+environments and produce novel constraints that are capable of fully ruling out
+dark matter models proposed to accommodate all the aforementioned excesses
+barring that of DAMPE. However, we do show that significant constraints can be
+placed upon the DAMPE parameter space with M31 data. In addition to this we
+project SKA non-observation constraints for the Reticulum II and Triangulum II
+dwarf galaxies and find these have potential to rule out cosmic-ray and
+gamma-ray excess-producing models of dark matter, even when the most
+conservative assumptions are employed.",1905.05599v5
+2019-05-20,"Exploring the damping of Alfvén waves along a long off-limb coronal loop, up to 1.4 R$_\odot$","The Alfv\'en wave energy flux in the corona can be explored using the
+electron density and velocity amplitude of the waves. The velocity amplitude of
+Alfv\'en waves can be obtained from the non-thermal velocity of the spectral
+line profiles. Previous calculations of the Alfv\'en wave energy flux with
+height in active regions and polar coronal holes have provided evidence for the
+damping of Alfv\'en waves with height. We present off-limb Hinode EUV imaging
+spectrometer (EIS) observations of a long coronal loop up to 1.4~R$_\odot$. We
+have obtained the electron density along the loop and found the loop to be
+almost in hydrostatic equilibrium. We obtained the temperature using the
+EM-loci method and found the loop to be isothermal across, as well as along,
+the loop with a temperature of about 1.37 MK. We significantly improve the
+estimate of non-thermal velocities over previous studies by using the estimated
+ion (equal to electron) temperature. Estimates of electron densities are
+improved using the significant updates of the CHIANTI v.8 atomic data. More
+accurate measurements of propagating Alfv\'en wave energy along the coronal
+loop and its damping are presented up to distances of 1.4 R$_\odot$, further
+than have been previously explored. The Alfv\'en wave energy flux obtained
+could contribute to a significant part of the coronal losses due to radiation
+along the loop.",1905.08194v2
+2019-06-14,Influence of External Magnetic Field on Dust$-$Acoustic Waves in a Capacitive RF Discharge,"This paper reports experiments on self$-$excited dust acoustic waves (DAWs)
+and its propagation characteristics in a magnetized rf discharge plasma. The
+DAWs are spontaneously excited in dusty plasma after adding more particles in
+the confining potential well and found to propagate in the direction of
+streaming ions. The spontaneous excitation of such low-frequency modes is
+possible due to the instabilities associated with streaming ions through the
+dust grain medium. The background E-field and neutral pressure determine the
+stability of excited DAWs. The characteristics of DAWs strongly depend on the
+strength of external magnetic field. The magnetic field of strength B $<$ 0.05
+T only modifies the characteristics of propagating waves in dusty plasma at
+moderate power and pressure, P = 3.5 W and p = 27 Pa respectively. It is found
+that DAWs start to be damped with increasing the magnetic field beyond B $>$
+0.05 T and get completely damped at higher magnetic field B $\sim$ 0.13 T.
+After lowering the power and pressure to 3 W and 23 Pa respectively, the
+excited DAWs in the absence of B are slightly unstable. In this case, the
+magnetic field only stabilizes and modifies the propagation characteristics of
+DAWs while the strength of B is increased up to 0.1 T or even higher. The
+modification of the sheath electric field where particles are confined in the
+presence of the external magnetic field is the main cause of the modification
+and damping of the DAWs in a magnetized rf discharge plasma.",1906.06255v2
+2019-06-18,A Dynamic Robotic Actuator with Variable Physical Stiffness and Damping,"This study is part of research aiming at increasing the range of dynamic
+tasks for teleoperated field robotics in order to allow operators to use the
+full range of human motions without being limited by the dynamics of the
+robotic manipulator. A new variable impedance actuator (VIA) was designed,
+capable of reproducing motions through teleoperation from precise positioning
+tasks to highly dynamic tasks. The design requirements based on previous human
+user studies were a stiffness changing time of 50 ms, a peak output velocity of
+20 rad/s and variable damping allowing to suppress undesired oscillations. This
+is a unique combination of features that was not met by other VIAs. The new
+design has three motors in parallel configuration: two responsible for changing
+the VIA's neutral position and effective stiffness through a sliding pivot
+point lever mechanism, and the third acting as variable damper. A prototype was
+built and its performance measured with an effective stiffness changing time of
+50 to 120 ms for small to large stiffness steps, nominal output velocity of 16
+rad/s and a variable damper with a damping torque from 0 to 3 Nm. Its effective
+stiffness range is 0.2 to 313 Nm/rad. This concludes that the new actuator is
+particularly suitable for highly dynamic tasks. At the same time, the new
+actuator is also very versatile, making it especially interesting for
+teleoperation and human-robot collaboration.",1906.07669v2
+2019-06-27,Frequency Fluctuations in Tunable and Nonlinear Microwave Cavities,"We present a model for how frequency fluctuations comparable to the total
+cavity linewidth may arise in tunable and nonlinear microwave cavities, and how
+these fluctuations affect the measurement of scattering matrix elements.
+Applying this model to the specific case of a two-sided cavity, we obtain
+closed-form expressions for the average scattering matrix elements in several
+important cases. A key signature of our model is the subtle deformation of the
+trajectories swept out by scattering matrix elements in the complex plane.
+Despite this signature, the fluctuating and non-fluctuating models are
+qualitatively similar enough to be mistaken for one another. In the case of
+tunable cavities we show that if one fails to account for these fluctuations
+then one will find damping rates that appear to depend on the tuning parameter,
+which is a common observation in such systems. In the case of a Kerr cavity, we
+show that there exists a fundamental lower bound to the scale of these
+frequency fluctuations in the steady state, imposed by quantum mechanical
+uncertainty, which can appreciably affect the apparent damping rates of the
+cavity as the strength of the nonlinearity approaches the single-photon level.
+By using the model we present as a fitting function for experimental data,
+however, one can extract both the true damping rates of the cavity and the
+effective scale of these frequency fluctuations over the scattering
+measurement's bandwidth. Lastly, we compare this new method for observing
+frequency fluctuations to other methods, one of which we extend beyond the
+regime of small fluctuations.",1906.11989v3
+2019-08-08,Anisotropic damping of the spin fluctuations in doped La2-xSrxCuO4 studied by resonant inelastic x-ray scattering,"We report high-resolution resonant inelastic x-ray scattering (RIXS)
+measurements of the collective spin fluctuations in three compositions of the
+superconducting cuprate system La2-xSrxCuO4. We have mapped out the excitations
+throughout much of the 2-D (h,k) Brillouin zone. The spin fluctuations in
+La2-xSrxCuO4 are found to be fairly well-described by a damped harmonic
+oscillator model, thus our data allows us to determine the full wavevector
+dependence of the damping parameter. This parameter increases with doping and
+is largest along the (h, h) line, where it is peaked near (0.2,0.2). We have
+used a new procedure to determine the absolute wavevector-dependent
+susceptibility for the doped compositions La2-xSrxCuO4 (x=0.12,0.16) by
+normalising our data to La2CuO4 measurements made with inelastic neutron
+scattering (INS). We find that the evolution with doping of the intensity of
+high-energy excitations measured by RIXS and INS is consistent. For the doped
+compositions, the wavevector-dependent susceptibility is much larger at
+(1/4,1/4) than at (1/2,0). It increases rapidly along the (h,h) line towards
+the antiferromagnetic wavevector of the parent compound (1/2,1/2). Thus, the
+strongest magnetic excitations, and those predicted to favour superconductive
+pairing, occur towards the (1/2,1/2) position as observed by INS.",1908.03086v2
+2019-08-14,Two-fluid simulations of waves in the solar chromosphere II. Propagation and damping of fast magneto-acoustic waves and shocks,"Waves and shocks traveling through the solar chromospheric plasma are
+influenced by its partial ionization and weak collisional coupling, and may
+become susceptible to multi-fluid effects, similar to interstellar shock waves.
+In this study, we consider fast magneto-acoustic shock wave formation and
+propagation in a stratified medium, that is permeated by a horizontal magnetic
+field, with properties similar to that of the solar chromosphere. The evolution
+of plasma and neutrals is modeled using a two-fluid code that evolves a set of
+coupled equations for two separate fluids. We observed that waves in neutrals
+and plasma, initially coupled at the upper photosphere, become uncoupled at
+higher heights in the chromosphere. This decoupling can be a consequence of
+either the characteristic spatial scale at the shock front, that becomes
+similar to the collisional scale, or the change in the relation between the
+wave frequency, ion cyclotron frequency, and the collisional frequency with
+height. The decoupling height is a sensitive function of the wave frequency,
+wave amplitude, and the magnetic field strength. We observed that decoupling
+causes damping of waves and an increase in the background temperature due to
+the frictional heating. The comparison between analytical and numerical results
+allows us to separate the role of the nonlinear effects from the linear ones on
+the decoupling and damping of waves.",1908.05262v1
+2019-09-16,Inviscid damping and enhanced dissipation of the boundary layer for 2D Navier-Stokes linearized around Couette flow in a channel,"We study the 2D Navier-Stokes equations linearized around the Couette flow
+$(y,0)^t$ in the periodic channel $\mathbb T \times [-1,1]$ with no-slip
+boundary conditions in the vanishing viscosity $\nu \to 0$ limit. We split the
+vorticity evolution into the free evolution (without a boundary) and a boundary
+corrector that is exponentially localized to at most an $O(\nu^{1/3})$ boundary
+layer. If the initial vorticity perturbation is supported away from the
+boundary, we show inviscid damping of both the velocity and the vorticity
+associated to the boundary layer. For example, our $L^2_t L^1_y$ estimate of
+the boundary layer vorticity is independent of $\nu$, provided the initial data
+is $H^1$. For $L^2$ data, the loss is only logarithmic in $\nu$. Note both such
+estimates are false for the vorticity in the interior. To the authors'
+knowledge, this inviscid decay of the boundary layer vorticity seems to be a
+new observation not previously isolated in the literature. Both velocity and
+vorticity satisfy the expected $O(\exp(-\delta\nu^{1/3}\alpha^{2/3}t))$
+enhanced dissipation in addition to the inviscid damping. Similar, but slightly
+weaker, results are obtained also for $H^1$ data that is against the boundary
+initially. For $L^2$ data against the boundary, we at least obtain the boundary
+layer localization and enhanced dissipation.",1909.07230v1
+2019-10-19,Anomalies in the switching dynamics of C-type antiferromagnets and antiferromagnetic nanowires,"Antiferromagnets (AFMs) are widely believed to be superior than ferromagnets
+in spintronics because of their high stability due to the vanishingly small
+stray field. It is thus expected that the order parameter of AFM should always
+align along the easy-axis of the crystalline anisotropy. In contrast to this
+conventional wisdom, we find that the AFM order parameter switches away from
+the easy-axis below a critical anisotropy strength when an AFM is properly
+tailored into a nano-structure. The switching time first decreases and then
+increases with the damping. Above the critical anisotropy, the AFM order
+parameter is stable and precesses under a microwave excitation. However, the
+absorption peak is not at resonance frequency even for magnetic damping as low
+as 0.01. To resolve these anomalies, we first ascertain the hidden role of
+dipolar interaction that reconstructs the energy landscape of the nano-system
+and propose a model of damped non-linear pendulum to explain the switching
+behavior. In this framework, the second anomaly appears when an AFM is close to
+the boundary between underdamped and overdamped phases, where the observed
+absorption lineshape has small quality factor and thus is not reliable any
+longer. Our results should be significant to extract the magnetic parameters
+through resonance techniques.",1910.08668v1
+2019-11-01,Importance of Giant Impact Ejecta for Orbits of Planets Formed during the Giant Impact Era,"Terrestrial planets are believed to be formed via giant impacts of Mars-sized
+protoplanets. Planets formed via giant impacts have highly eccentric orbits. A
+swarm of planetesimals around the planets may lead to eccentricity damping for
+the planets via the equipartition of random energies (dynamical friction).
+However, dynamical friction increases eccentricities of planetesimals,
+resulting in high velocity collisions between planetesimals. The collisional
+cascade grinds planetesimals to dust until dust grains are blown out due to
+radiation pressure. Therefore, the total mass of planetesimals decreases due to
+collisional fragmentation, which weakens dynamical friction. We investigate the
+orbital evolution of protoplanets in a planetesimal disk, taking into account
+collisional fragmentation of planetesimals. For 100 km-sized or smaller
+planetesimals, dynamical friction is insignificant for eccentricity damping of
+planets because of collisional fragmentation. On the other hand, giant impacts
+eject collisional fragments. Although the total mass of giant impact ejecta is
+0.1-0.3 Earth masses, the largest impact ejecta are ~ 1,000 km in size. We also
+investigate the orbital evolution of single planets with initial eccentricities
+0.1 in a swarm of such giant impact ejecta. Although the total mass of giant
+impact ejecta decreases by a factor of 3 in 30 Myrs, eccentricities of planets
+are damped down to the Earth level (~0.01) due to interaction with giant impact
+ejecta. Therefore, giant impact ejecta play an important role for determination
+of terrestrial planet orbits.",1911.00278v3
+2019-11-06,Damping in Ru/Co-based multilayer films with large Dzyaloshinskii-Moriya interaction,"Recent development of the magnetic material engineering led to achievement of
+the systems with a high interfacial Dzyaloshinskii-Moriya interaction (DMI). As
+a result, the formation of non-collinear magnetic soliton states or
+nonreciprocal spin wave dynamics is achievable. Typically used materials are
+based on bi-layers Heavy Metal/Ferromagnet, e.g., Pt/Co. These layers are
+characterized not only by a strong DMI, but also by the spin pumping effect and
+the resulting relatively large damping. Here, we show that the considerable
+interfacial DMI can be also present in bi-layers based on Ru/Co, characterized
+with low spin pumping effect and low damping. It is therefore a good candidate
+for the dynamical studies and implementations of chiral DMI. It is demonstrated
+by theoretical calculations that the value of DMI can be strongly affected and
+controlled by the strain of the lattice. We show a systematic experimental and
+theoretical comparison of magnetic material parameters between Pt/Co and Ru/Co
+bi-layers as a deserving candidate for spintronic and spin-orbitronic
+applications.",1911.02467v1
+2019-11-14,Studies of the beam-ion instability and its mitigation with feedback system,"The beam-ion interaction is a potential limitation of beam performance in
+electron accelerators, especially where the beam emittance is of a great
+concern in future ultra-low emittance light source. ""Conventionally"", the beam
+instability due to beam-ion interaction is attributed to two types of effects:
+ion trapping effect and fast ion effect, which emphasize the beam-ion dynamics
+in different time scales. Whereas, in accelerators, the beam suffers from a
+mixture of ion trapping effect and fast ion effect, leading to a more
+complicated process and requiring a self-consistent treatment. To evaluate the
+beam characteristics, as emittance growth under the influence from beam-ion
+effect, a new numerical simulation code based on the ""quasi-strong-strong""
+model has been developed, including modules of ionization, beam-ion
+interaction, synchrotron radiation damping, quantum excitation, bunch-by-bunch
+feedback, etc. In the study, we do not regularly distinguish the ion trapping
+effect and the fast ion effect, but treat beam-ion interaction more generally
+and consistently. The lattice of High Energy Photon Source, a diffraction limit
+ring under construction in Beijing, is used as an example to show the beam-ion
+effect. It is found that in this low emittance ring, the beam-ion instability
+is not a dominant mechanism in operation mode with a high beam current, but
+seriously occurs in a lower beam current region. When the beam-ion instability
+were significantly driven and can not be damped by the synchrotron radiation
+damping, the simulations show the bunch-by-bunch feedback system based on the
+Finite Impulse Response filter technique can be adopted to mitigate it
+effectively.",1911.05958v1
+2019-12-05,Steering magnonic dynamics and permeability at exceptional points in a parity-time symmetric waveguide,"Tuning the low-energy magnetic dynamics is a key element in designing novel
+magnetic metamaterials, spintronic devices and magnonic logic circuits. This
+study uncovers a new, highly effective way of controlling the magnetic
+permeability via shaping the magnonic properties in coupled magnetic waveguides
+separated by current carrying spacer with strong spin-orbit coupling. The
+spin-orbit torques exerted on the waveguides leads to an externally tunable
+enhancement of magnetic damping in one waveguide and a decreased damping in the
+other, constituting so a magnetic parity-time (PT) symmetric system with
+emergent magnetic properties at the verge of the exceptional point where
+magnetic gains/losses are balanced. In addition to controlling the magnetic
+permeability, phenomena inherent to PT-symmetric systems are identified,
+including the control on magnon power oscillations, nonreciprocal magnon
+propagation, magnon trapping and enhancement as well as the increased
+sensitivity to magnetic perturbation and abrupt spin reversal. These
+predictions are demonstrated analytically and confirmed by full numerical
+simulations under experimentally feasible conditions. The position of the
+exceptional points and the strength of the spontaneous PT symmetry breaking can
+be tuned by external electric and/or magnetic fields. The roles of the
+intrinsic magnetic damping, and the possibility of an electric control via
+Dzyaloshinskii-Moriya interaction are exposed and utilized for mode dispersion
+shaping and magnon amplification and trapping. The results point to a new route
+to designing optomagnonic waveguides, traps, sensors, and circuits.",1912.02500v1
+2020-01-13,Modelling Stochastic Signatures in Classical Pulsators,"We consider the impact of stochastic perturbations on otherwise coherent
+oscillations of classical pulsators. The resulting dynamics are modelled by a
+driven damped harmonic oscillator subject to either an external or an internal
+forcing and white noise velocity fluctuations. We characterize the phase and
+relative amplitude variations using analytical and numerical tools. When the
+forcing is internal the phase variation displays a random walk behaviour and a
+red noise power spectrum with a ragged erratic appearance. We determine the
+dependence of the root mean square phase and relative amplitude variations
+($\sigma_{\Delta \varphi}$ and $\sigma_{\Delta A/A}$, respectively) on the
+amplitude of the stochastic perturbations, the damping constant $\eta$, and the
+total observation time $t_{\rm obs}$ for this case, under the assumption that
+the relative amplitude variations remain small, showing that $\sigma_{\Delta
+\varphi}$ increases with $t_{\rm obs}^{1/2}$ becoming much larger than
+$\sigma_{\Delta A/A}$ for $t_{\rm obs} \gg \eta^{-1}$. In the case of an
+external forcing the phase and relative amplitude variations remain of the same
+order, independent of the observing time. In the case of an internal forcing,
+we find that $\sigma_{\Delta \varphi}$ does not depend on $\eta$. Hence, the
+damping time cannot be inferred from fitting the power of the signal, as done
+for solar-like pulsators, but the amplitude of the stochastic perturbations may
+be constrained from the observations. Our results imply that, given sufficient
+time, the variation of the phase associated to the stochastic perturbations in
+internally driven classical pulsators will become sufficiently large to be
+probed observationally.",2001.04558v1
+2020-01-23,Skyrmion Dynamics and Topological Sorting on Periodic Obstacle Arrays,"We examine skyrmions under a dc drive interacting with a square array of
+obstacles for varied obstacle size and damping. When the drive is applied in a
+fixed direction, we find that the skyrmions are initially guided in the drive
+direction but also move transverse to the drive due to the Magnus force. The
+skyrmion Hall angle, which indicates the difference between the skyrmion
+direction of motion and the drive direction, increases with drive in a series
+of quantized steps as a result of the locking of the skyrmion motion to
+specific symmetry directions of the obstacle array. On these steps, the
+skyrmions collide with an integer number of obstacles to create a periodic
+motion. The transitions between the different locking steps are associated with
+jumps or dips in the velocity-force curves. In some regimes, the skyrmion Hall
+angle is actually higher than the intrinsic skyrmion Hall angle that would
+appear in the absence of obstacles. In the limit of zero damping, the skyrmion
+Hall angle is 90$^\circ$, and we find that it decreases as the damping
+increases. For multiple interacting skyrmion species in the collective regime,
+we find jammed behavior at low drives where the different skyrmion species are
+strongly coupled and move in the same direction. As the drive increases, the
+species decouple and each can lock to a different symmetry direction of the
+obstacle lattice, making it possible to perform topological sorting in analogy
+to the particle sorting methods used to fractionate different species of
+colloidal particles moving over two-dimensional obstacle arrays.",2001.08835v1
+2020-03-03,Linear stability analysis for 2D shear flows near Couette in the isentropic Compressible Euler equations,"In this paper, we investigate linear stability properties of the 2D
+isentropic compressible Euler equations linearized around a shear flow given by
+a monotone profile, close to the Couette flow, with constant density, in the
+domain $\mathbb{T}\times \mathbb{R}$. We begin by directly investigating the
+Couette shear flow, where we characterize the linear growth of the compressible
+part of the fluid while proving time decay for the incompressible part
+(inviscid damping with slower rates). Then we extend the analysis to monotone
+shear flows near Couette, where we are able to give an upper bound, superlinear
+in time, for the compressible part of the fluid. The incompressible part enjoys
+an inviscid damping property, analogous to the Couette case. In the pure
+Couette case, we exploit the presence of an additional conservation law (which
+connects the vorticity and the density on the moving frame) in order to reduce
+the number of degrees of freedom of the system. The result then follows by
+using weighted energy estimates. In the general case, unfortunately, this
+conservation law no longer holds. Therefore we define a suitable weighted
+energy functional for the whole system, which can be used to estimate the
+irrotational component of the velocity but does not provide sharp bounds on the
+solenoidal component. However, even in the absence of the aforementioned
+additional conservation law, we are still able to show the existence of a
+functional relation which allows us to recover somehow the vorticity from the
+density, on the moving frame. By combining the weighted energy estimates with
+the functional relation we also recover the inviscid damping for the solenoidal
+component of the velocity.",2003.01694v1
+2020-03-06,Lattice dynamics and polarization-dependent phonon damping in $α$-phase FeSi$_{2}$ nanoislands,"We determined the lattice dynamics of metastable, surface-stabilized
+$\alpha$-phase FeSi$_2$ nanoislands epitaxially grown on the Si(111) surface
+with average heights and widths ranging from 1.5 to 20 nm and 18 to 72 nm,
+respectively. The crystallographic orientation, surface morphology and local
+crystal structure of the nanoislands were investigated by reflection
+high-energy electron diffraction, atomic force microscopy and X-ray absorption
+spectroscopy. The Fe-partial phonon density of states (PDOS), obtained by
+nuclear inelastic scattering, exhibits a pronounced damping and broadening of
+the spectral features with decreasing average island height. First-principles
+calculations of the polarization-projected Si- and Fe-partial phonon
+dispersions and PDOS enable the disentanglement of the contribution of the
+$xy$- and $z$-polarized phonons to the experimental PDOS. Modeling of the
+experimental data with the theoretical results unveils an enhanced damping of
+the $z$-polarized phonons for islands with average sizes below 10 nm. This
+phenomenon is attributed to the fact that the low-energy $z$-polarized phonons
+couple to the low-energy surface/interface vibrational modes. The thermodynamic
+and elastic properties obtained from the experimental data show a pronounced
+size-dependent behavior.",2003.02969v1
+2020-03-20,The resonant drag instability of dust streaming in turbulent protoplanetary disc,"Damping of the previously discovered resonant drag instability (RDI) of dust
+streaming in protoplanetary disc is studied using the local approach to
+dynamics of gas-dust perturbations in the limit of the small dust fraction.
+Turbulence in a disc is represented by the effective viscosity and diffusivity
+in equations of motion for gas and dust, respectively. In the standard case of
+the Schmidt number (ratio of the effective viscosity to diffusivity) Sc = 1,
+the reduced description of RDI in terms of the inertial wave (IW) and the
+streaming dust wave (SDW) falling in resonance with each other reveals that
+damping solution differs from the inviscid solution simply by adding the
+characteristic damping frequency to its growth rate. RDI is fully suppressed at
+the threshold viscosity, which is estimated analytically, first, for radial
+drift, next, for vertical settling of dust, and at last, in the case of
+settling combined with radial drift of the dust. In the last case, RDI survives
+up to the highest threshold viscosity, with a greater excess for smaller
+solids. Once Sc \neq 1, a new instability specific for dissipative
+perturbations on the dust settling background emerges. This instability of the
+quasi-resonant nature is referred to as settling viscous instability (SVI). The
+mode akin to SDW (IW) becomes growing in a region of long waves provided that
+Sc > 1 (Sc < 1). SVI leads to an additional increase of the threshold
+viscosity.",2003.09212v1
+2020-05-27,Role of diffusive surface scattering in nonlocal plasmonics,"The recent generalised nonlocal optical response (GNOR) theory for plasmonics
+is analysed, and its main input parameter, namely the complex hydrodynamic
+convection-diffusion constant, is quantified in terms of enhanced Landau
+damping due to diffusive surface scattering of electrons at the surface of the
+metal. GNOR has been successful in describing plasmon damping effects, in
+addition to the frequency shifts originating from induced-charge screening,
+through a phenomenological electron diffusion term implemented into the
+traditional hydrodynamic Drude model of nonlocal plasmonics. Nevertheless, its
+microscopic derivation and justification is still missing. Here we discuss how
+the inclusion of a diffusion-like term in standard hydrodynamics can serve as
+an efficient vehicle to describe Landau damping without resorting to
+computationally demanding quantum-mechanical calculations, and establish a
+direct link between this term and the Feibelman $d$ parameter for the centroid
+of charge. Our approach provides a recipe to connect the phenomenological
+fundamental GNOR parameter to a frequency-dependent microscopic
+surface-response function. We therefore tackle one of the principal limitations
+of the model, and further elucidate its range of validity and limitations, thus
+facilitating its proper application in the framework of nonclassical
+plasmonics.",2005.13218v2
+2020-07-15,On the Extension of Linear Damping to Quantum Mechanics through Fractionary Momentum Operators Pt. I,"The use of fractional momentum operators and fractionary kinetic energy used
+to model linear damping in dissipative systems such as resistive circuits and a
+spring-mass ensambles was extended to a quantum mechanical formalism. Three
+important associated 1 dimensional problems were solved: the free particle
+case, the infinite potential well, and the harmonic potential. The wave
+equations generated reproduced the same type of 2-order ODE observed in
+classical dissipative systems, and produced quantized energy levels. In the
+infinite potential well, a zero-point energy emerges, which can be fitted to
+the rest energy of the particle described by special relativity, given by
+relationship $E_r=mc^2$. In the harmonic potential, new fractional creation and
+destruction operators were introduced to solve the problem in the energy basis.
+The energy eigenvalues found are different to the ones reported by earlier
+approaches to the quantum damped oscillator problem reported by other authors.
+In this case, a direct relationship between the relativistic rest energy of the
+particle and the expected value of the fractionary kinetic energy in the base
+state was obtained. We conclude that there exists a relationship between
+fractional kinetic energy and special relativity energies, that remains unclear
+and needs further exploration, but also conclude that the current form of
+transforming fractionary momentum operators to the position basis will yield
+non-observable imaginary momentum quantities, and thus a correction to the way
+of transforming them needs to be explored further.",2007.07434v3
+2020-07-18,Results from the Alfvén Eigenmode Active Diagnostic during the 2019-2020 JET deuterium campaign,"This paper presents results of extensive analysis of mode excitation observed
+during the operation of the Alfv\'{e}n Eigenmode Active Diagnostic (AEAD) in
+the JET tokamak during the 2019-2020 deuterium campaign. Six of eight
+toroidally spaced antennas, each with independent power and phasing, were
+successful in actively exciting stable MHD modes in 479 plasmas. In total, 4768
+magnetic resonances were detected with up to fourteen fast magnetic probes. In
+this work, we present the calculations of resonant frequencies $f_0$, damping
+rates $\gamma < 0$, and toroidal mode numbers $n$, spanning the parameter range
+$f_0 \approx$ 30 - 250 kHz, $-\gamma \approx$ 0 - 13 kHz, and $\vert n \vert
+\leq 30$. In general, good agreement is seen between the resonant and the
+calculated toroidal Alfv\'{e}n Eigenmode frequencies, and between the toroidal
+mode numbers applied by the AEAD and estimated of the excited resonances. We
+note several trends in the database: the probability of resonance detection
+decreases with plasma current and external heating power; the normalized
+damping rate increases with edge safety factor but decreases with external
+heating. These results provide key information to prepare future experimental
+campaigns and to better understand the physics of excitation and damping of
+Alfv\'{e}n Eigenmodes in the presence of alpha particles during the upcoming DT
+campaign, thereby extrapolating with confidence to future tokamaks.",2007.09412v1
+2020-08-18,A Quasi-Linear Diffusion Model for Resonant Wave-Particle Instability in Homogeneous Plasma,"In this paper, we develop a model to describe the generalized wave-particle
+instability in a quasi-neutral plasma. We analyze the quasi-linear diffusion
+equation for particles by expressing an arbitrary unstable and resonant wave
+mode as a Gaussian wave packet, allowing for an arbitrary direction of
+propagation with respect to the background magnetic field. We show that the
+localized energy density of the Gaussian wave packet determines the
+velocity-space range in which the dominant wave-particle instability and
+counter-acting damping contributions are effective. Moreover, we derive a
+relation describing the diffusive trajectories of resonant particles in
+velocity space under the action of such an interplay between the wave-particle
+instability and damping. For the numerical computation of our theoretical
+model, we develop a mathematical approach based on the Crank-Nicolson scheme to
+solve the full quasi-linear diffusion equation. Our numerical analysis solves
+the time evolution of the velocity distribution function under the action of a
+dominant wave-particle instability and counteracting damping and shows a good
+agreement with our theoretical description. As an application, we use our model
+to study the oblique fast-magnetosonic/whistler instability, which is proposed
+as a scattering mechanism for strahl electrons in the solar wind. In addition,
+we numerically solve the full Fokker-Planck equation to compute the time
+evolution of the electron-strahl distribution function under the action of
+Coulomb collisions with core electrons and protons after the collisionless
+action of the oblique fast-magnetosonic/whistler instability.",2008.08169v2
+2020-09-10,Spin waves in alloys at finite temperatures: application for FeCo magnonic crystal,"We study theoretically the influence of the temperature and disorder on the
+spin wave spectrum of the magnonic crystal Fe$_{1-c}$Co$_{c}$. Our formalism is
+based on the analysis of a Heisenberg Hamiltonian by means of the wave vector
+and frequency dependent transverse magnetic susceptibility. The exchange
+integrals entering the model are obtained from the \emph{ab initio} magnetic
+force theorem. The coherent potential approximation is employed to treat the
+disorder and random phase approximation in order to account for the softening
+of the magnon spectrum at finite temperatures. The alloy turns out to exhibit
+many advantageous properties for spintronic applications. Apart from high Curie
+temperature, its magnonic bandgap remains stable at elevated temperatures and
+is largely unaffected by the disorder. We pay particular attention to the
+attenuation of magnons introduced by the alloying. The damping turns out to be
+a non-monotonic function of the impurity concentration due to the non-trivial
+evolution of the value of exchange integrals with the Co concentration. The
+disorder induced damping of magnons is estimated to be much smaller than their
+Landau damping.",2009.04712v6
+2020-09-14,On the response of a star cluster to a tidal perturbation,"We study the response of star clusters to individual tidal perturbations
+using controlled $N$-body simulations. We consider perturbations by a moving
+point mass and by a disc, and vary the duration of the perturbation as well as
+the cluster density profile. For fast perturbations (i.e. `shocks'), the
+cluster gains energy in agreement with theoretical predictions in the impulsive
+limit. For slow disc perturbations, the energy gain is lower, and this has
+previously been attributed to adiabatic damping. However, the energy gain due
+to slow perturbations by a point-mass is similar to, or larger than that due to
+fast shocks, which is not expected because adiabatic damping should be almost
+independent of the nature of the tides. We show that the geometric distortion
+of the cluster during slow perturbations is of comparable importance for the
+energy gain as adiabatic damping, and that the combined effect can
+qualitatively explain the results. The half-mass radius of the bound stars
+after a shock increases up to $\sim$7\% for low-concentration clusters, and
+decreases $\sim$3\% for the most concentrated ones. The fractional mass loss is
+a non-linear function of the energy gain, and depends on the nature of the
+tides and most strongly on the cluster density profile, making semi-analytic
+model predictions for cluster lifetimes extremely sensitive to the adopted
+density profile.",2009.06643v2
+2020-09-18,African Easterly Waves in an Idealized General Circulation Model: Instability and Wavepacket Diagnostics,"We examine the group dynamic of African easterly waves (AEW) generated in a
+realistic, spatially non-homogeneous African easterly jet (AEJ) using an
+idealized general circulation model. Our objective is to investigate whether
+the limited zonal extent of the AEJ is an impediment to AEW development. We
+construct a series of basic states using global reanalysis fields and
+initialize waves via transient heating over West Africa. The dominant response
+is a localized wavepacket that disperses upstream and downstream. The inclusion
+of a crude representation of boundary layer damping stabilizes the waves in
+most cases. In some basic states, however, exponential growth occurs even in
+the presence of damping. This shows that AEWs can occasionally emerge
+spontaneously. The key result is that the wavepacket in almost all cases
+remains within the AEJ instead of being swept away. Drawing from other studies,
+this also suggests that even the damped waves can grow if coupled with
+additional sources of energy such as moist convection and dust radiative
+feedback. The wavepacket in the localized AEJ appears to satisfy a condition
+for absolute instability, a form of spatial hydrodynamic instability. However,
+this needs to be verified more rigorously. Our results also suggest that the
+intermittent nature of AEWs is mediated, not by transitions between convective
+and absolute instability, but likely by external sources such as propagating
+equatorial wave modes",2009.08604v1
+2020-09-25,Polaronic Contributions to Friction in a Manganite Thin Film,"Despite the huge importance of friction in regulating movement in all natural
+and technological processes, the mechanisms underlying dissipation at a sliding
+contact are still a matter of debate. Attempts to explain the dependence of
+measured frictional losses at nanoscale contacts on the electronic degrees of
+freedom of the surrounding materials have so far been controversial. Here, it
+is proposed that friction can be explained by considering damping of stick-slip
+pulses in a sliding contact. Based on friction force microscopy studies of
+La$_{(1-x)}$Sr$_x$MnO$_3$ films at the ferromagnetic-metallic to
+paramagnetic-polaronic conductor phase transition, it is confirmed that the
+sliding contact generates thermally-activated slip pulses in the nanoscale
+contact, and argued that these are damped by direct coupling into phonon bath.
+Electron-phonon coupling leads to the formation of Jahn-Teller polarons and a
+clear increase in friction in the high temperature phase. There is no evidence
+for direct electronic drag on the atomic force microscope tip nor any
+indication of contributions from electrostatic forces. This intuitive scenario,
+that friction is governed by the damping of surface vibrational excitations,
+provides a basis for reconciling controversies in literature studies as well as
+suggesting possible tactics for controlling friction.",2009.12137v1
+2020-10-08,Modeling of the ECCD injection effect on the Heliotron J and LHD plasma stability,"The aim of the study is to analyze the stability of the Energetic Particle
+Modes (EPM) and Alfven Eigenmodes (AE) in Helitron J and LHD plasma if the
+electron cyclotron current drive (ECCD) is applied. The analysis is performed
+using the code FAR3d that solves the reduced MHD equations describing the
+linear evolution of the poloidal flux and the toroidal component of the
+vorticity in a full 3D system, coupled with equations of density and parallel
+velocity moments for the energetic particle (EP) species, including the effect
+of the acoustic modes. The Landau damping and resonant destabilization effects
+are added via the closure relation. The simulation results show that the n=1
+EPM and n=2 Global AE (GAE) in Heliotron J plasma can be stabilized if the
+magnetic shear is enhanced at the plasma periphery by an increase (co-ECCD
+injection) or decrease (ctr-ECCD injection) of the rotational transform at the
+magnetic axis iota0. In the ctr-ECCD simulations, the EPM/AE growth rate
+decreases only below a given iota0, similar to the ECCD intensity threshold
+observed in the experiments. In addition, ctr-ECCD simulations show an
+enhancement of the continuum damping. The simulations of the LHD discharges
+with ctr-ECCD injection indicate the stabilization of the n=1 EPM, n=2 Toroidal
+AE (TAE) and n=3 TAE, caused by an enhancement of the continuum damping in the
+inner plasma leading to a higher EP beta threshold with respect to the co- and
+no-ECCD simulations.",2010.03892v1
+2020-10-14,Kink Oscillations in Solar Coronal Loops with Elliptical Cross-Sections. I. the linear regime,"The cross sections of solar coronal loops are suggested to be rarely
+circular. We examine linear kink oscillations in straight, density-enhanced,
+magnetic cylinders with elliptical cross-sections by solving the
+three-dimensional magnetohydrodynamic equations from an initial-value-problem
+perspective. Motivated by relevant eigen-mode analyses, we distinguish between
+two independent polarizations, one along the major axis (the M-modes) and the
+other along the minor one (the m-modes). We find that, as happens for coronal
+loops with circular cross-sections, the apparent damping of the transverse
+displacement of the loop axis is accompanied by the accumulation of transverse
+Alfv\'enic motions and the consequent development of small-scales therein,
+suggesting the robustness of the concepts of resonant absorption and
+phase-mixing. In addition, two stages can in general be told apart in the
+temporal evolution of the loop displacement; a Gaussian time dependence
+precedes an exponential one. For the two examined density ratios between loops
+and their surroundings, the periods of the M-modes (m-modes) tend to increase
+(decrease) with the major-to-minor-half-axis ratio, and the damping times in
+the exponential stage for the M-modes tend to exceed their m-mode counterparts.
+This is true for the two transverse profiles we examine. However, the relative
+magnitudes of the damping times in the exponential stage for different
+polarizations depend on the specification of the transverse profile and/or the
+density contrast. The applications of our numerical findings are discussed in
+the context of coronal seismology.",2010.06991v1
+2020-11-04,The impact of astrophysical dust grains on the confinement of cosmic rays,"We argue that charged dust grains could significantly impact the confinement
+and transport of galactic cosmic rays. For sub-GeV to ~1000GeV cosmic rays,
+small-scale parallel Alfv\'en waves, which isotropize cosmic rays through
+gyro-resonant interactions, are also gyro-resonant with charged grains. If the
+dust is nearly stationary, as in the bulk of the interstellar medium, Alfv\'en
+waves are damped by dust. This will reduce the amplitude of Alfv\'en waves
+produced by the cosmic rays through the streaming instability, thus enhancing
+cosmic-ray transport. In well-ionized regions, the dust damping rate is larger
+by a factor of ~10 than other mechanisms that damp parallel Alfv\'en waves at
+the scales relevant for ~GeV cosmic rays, suggesting that dust could play a key
+role in regulating cosmic-ray transport. In astrophysical situations in which
+the dust moves through the gas with super-Alfv\'enic velocities, Alfv\'en waves
+are rendered unstable, which could directly scatter cosmic rays. This
+interaction has the potential to create a strong feedback mechanism where dust,
+driven through the gas by radiation pressure, then strongly enhances the
+confinement of cosmic rays, increasing their capacity to drive outflows. This
+mechanism may act in the circumgalactic medium around star-forming galaxies and
+active galactic nuclei.",2011.02497v2
+2020-11-17,A Phase Resonance Approach for Modal Testing of Structures with Nonlinear Dissipation,"The concept of nonlinear modes is useful for the dynamical characterization
+of nonlinear mechanical systems. While efficient and broadly applicable methods
+are now available for the computation of nonlinear modes, nonlinear modal
+testing is still in its infancy. The purpose of this work is to overcome its
+present limitation to conservative nonlinearities. Our approach relies on the
+recently extended periodic motion concept, according to which nonlinear modes
+of damped systems are defined as family of periodic motions induced by an
+appropriate artificial excitation that compensates the natural dissipation. The
+particularly simple experimental implementation with only a single-point,
+single-frequency, phase resonant forcing is analyzed in detail. The method
+permits the experimental extraction of natural frequencies, modal damping
+ratios and deflection shapes (including harmonics), for each mode of interest,
+as function of the vibration level. The accuracy, robustness and current
+limitations of the method are first demonstrated numerically. The method is
+then verified experimentally for a friction-damped system. Moreover, a
+self-contained measure for estimating the quality of the extracted modal
+properties is investigated. The primary advantages over alternative vibration
+testing methods are noise robustness, broad applicability and short measurement
+duration. The central limitation of the identified modal quantities is that
+they only characterize the system in the regime near isolated resonances.",2011.08500v1
+2020-12-08,"Meta Learning-based MIMO Detectors: Design, Simulation, and Experimental Test","Deep neural networks (NNs) have exhibited considerable potential for
+efficiently balancing the performance and complexity of multiple-input and
+multiple-output (MIMO) detectors. We propose a receiver framework that enables
+efficient online training by leveraging the following simple observation:
+although NN parameters should adapt to channels, not all of them are
+channel-sensitive. In particular, we use a deep unfolded NN structure that
+represents iterative algorithms in signal detection and channel decoding
+modules as multi layer deep feed forward networks. An expectation propagation
+(EP) module, called EPNet, is established for signal detection by unfolding the
+EP algorithm and rendering the damping factors trainable. An unfolded turbo
+decoding module, called TurboNet, is used for channel decoding. This component
+decodes the turbo code, where trainable NN units are integrated into the
+traditional max-log-maximum a posteriori decoding procedure. We demonstrate
+that TurboNet is robust for channels and requires only one off-line training.
+Therefore, only a few damping factors in EPNet must be re-optimized online. An
+online training mechanism based on meta learning is then developed. Here, the
+optimizer, which is implemented by long short-term memory NNs, is trained to
+update damping factors efficiently by using a small training set such that they
+can quickly adapt to new environments. Simulation results indicate that the
+proposed receiver significantly outperforms traditional receivers and that the
+online learning mechanism can quickly adapt to new environments. Furthermore,
+an over-the-air platform is presented to demonstrate the significant robustness
+of the proposed receiver in practical deployment.",2012.04379v1
+2020-12-31,Adaptive Surgical Robotic Training Using Real-Time Stylistic Behavior Feedback Through Haptic Cues,"Surgical skill directly affects surgical procedure outcomes; thus, effective
+training is needed to ensure satisfactory results. Many objective assessment
+metrics have been developed and some are widely used in surgical training
+simulators. These objective metrics provide the trainee with descriptive
+feedback about their performance however, often lack feedback on how to proceed
+to improve performance. The most effective training method is one that is
+intuitive, easy to understand, personalized to the user and provided in a
+timely manner. We propose a framework to enable user-adaptive training using
+near-real-time detection of performance, based on intuitive styles of surgical
+movements (e.g., fluidity, smoothness, crispness, etc.), and propose a haptic
+feedback framework to assist with correcting styles of movement. We evaluate
+the ability of three types of force feedback (spring, damping, and spring plus
+damping feedback), computed based on prior user positions, to improve different
+stylistic behaviors of the user during kinematically constrained reaching
+movement tasks. The results indicate that four out of the six styles studied
+here were statistically significantly improved (p<0.05) using spring guidance
+force feedback and a significant reduction in task time was also found using
+spring feedback. The path straightness and targeting error in the task were
+other task performance metrics studied which were improved significantly using
+the spring-damping feedback. This study presents a groundwork for adaptive
+training in robotic surgery based on near-real-time human-centric models of
+surgical behavior.",2101.00097v3
+2021-01-08,Damped dust-ion-acoustic solitons in collisional magnetized nonthermal plasmas,"A multi-species magnetized collisional nonthermal plasma system containing
+inertial ion species, non-inertial electron species following nonthermal
+$\kappa-$ distribution, and immobile dust particles, is considered to examine
+the characteristics of the dissipative dust-ion-acoustic (DIA) soliton modes,
+\textbf{theoretically and parametrically}. The electrostatic solitary modes are
+found to be associated with the low frequency dissipative dust-ion-acoustic
+solitary waves (DIASWs). The ion-neutral collision is taken into account, and
+the influence of ion-neutral collisional effects on the dynamics of dissipative
+DIASWs is investigated. It is reported that most of the plasma mediums in space
+and laboratory are far from thermal equilibrium, and the particles in such
+plasma systems are well fitted via the $\kappa-$nonthermal distribution than
+via the thermal Maxwellian distribution. The reductive perturbation approach is
+adopted to derive the damped KdV (dKdV) equation, and the solitary wave
+solution of the dKdV equation is derived via the tangent hyperbolic method to
+analyze the basic features (amplitude, width, speed, time evolution, etc.) of
+dissipative DIASWs. The propagation nature and also the basic features of
+dissipative DIASWs are seen to influence significantly due to the variation of
+the plasma configuration parameters and also due to the variation of the
+supethermality index $\kappa$ in the considered plasma system. The implication
+of the results of this study could be useful for better understanding the
+electrostatic localized disturbances, in the ion length and time scale, in
+space and experimental dusty plasmas, where the presence of excess energetic
+electrons and ion-neutral collisional damping are accountable.",2101.03183v2
+2020-12-28,Global complexity effects due to local damping in a nonlinear system in 1:3 internal resonance,"It is well-known that nonlinearity may lead to localization effects and
+coupling of internally resonant modes. However, research focused primarily on
+conservative systems commonly assumes that the near-resonant forced response
+closely follows the autonomous dynamics. Our results for even a simple system
+of two coupled oscillators with a cubic spring clearly contradict this common
+belief. We demonstrate analytically and numerically global effects of a weak
+local damping source in a harmonically forced nonlinear system under condition
+of 1:3 internal resonance: The global motion becomes asynchronous, i.e., mode
+complexity is introduced with a non-trivial phase difference between the modal
+oscillations. In particular, we show that a maximum mode complexity with a
+phase difference of $90^\circ$ is attained in a multi-harmonic sense. This
+corresponds to a transition from generalized standing to traveling waves in the
+system's modal space. We further demonstrate that the localization is crucially
+affected by the system's damping. Finally, we propose an extension of the
+definition of mode complexity and mode localization to nonlinear quasi-periodic
+motions, and illustrate their application to a quasi-periodic regime in the
+forced response.",2101.03233v1
+2021-01-28,Vortex-induced Vibrations of a Confined Circular Cylinder for Efficient Flow Power Extraction,"A simple method to increase the flow power extraction efficiency of a
+circular cylinder, undergoing vortex-induced vibration (VIV), by confining it
+between two parallel plates is proposed. A two-dimensional numerical study was
+performed on VIV of a circular cylinder inside a parallel plate channel of
+height H at Reynolds number 150 to quantify the improvement. The cylinder is
+elastically mounted with a spring such that it is only free to vibrate in the
+direction transverse to the channel flow and has a fixed mass ratio (m*) of 10.
+The energy extraction process is modelled as a damper, with spatially constant
+damping ration ((), attached to the cylinder. The simulations are performed by
+varying the reduced velocity for a set of fixed mass-damping ({\alpha} = m*()
+values ranging between 0 to 1. The blockage ratio (b = D/H) is varied from 0.25
+to 0.5 by changing the channel height. The quasi-periodic initial branch found
+for the unconfined cylinder shrinks with the increasing blockage. The extracted
+power is found to increase rapidly with the blockage. For maximum blockage (b =
+0.2), the maximum flow power extracted by the cylinder is an order of magnitude
+larger as compared to what it would extract in an open domain with free stream
+velocity equal to the channel mean velocity. The optimal mass-damping
+({\alpha}c ) for extracting maximum power is found to lie between 0.2 to 0.3.
+An expression is derived to predict the maximum extracted power from the
+undamped response of a confined/unconfined cylinder. With the assumption
+{\alpha}c = 0.25, the derived expression can predict the maximum power
+extraction within +-20% of the actual values obtained from present and previous
+numerical and experimental studies.",2101.11803v1
+2021-03-08,"A Self-Consistent, Time-Dependent Treatment of Dynamical Friction: New Insights regarding Core Stalling and Dynamical Buoyancy","Dynamical friction is typically regarded a secular process, in which the
+subject ('perturber') evolves very slowly (secular approximation), and has been
+introduced to the host over a long time (adiabatic approximation). These
+assumptions imply that dynamical friction arises from the LBK torque with
+non-zero contribution only from pure resonance orbits. However, dynamical
+friction is only of astrophysical interest if its timescale is shorter than the
+age of the Universe. In this paper we therefore relax the adiabatic and secular
+approximations. We first derive a generalized LBK torque, which reduces to the
+LBK torque in the adiabatic limit, and show that it gives rise to transient
+oscillations due to non-resonant orbits that slowly damp out, giving way to the
+LBK torque. This is analogous to how a forced, damped oscillator undergoes
+transients before settling to a steady state, except that here the damping is
+due to phase mixing rather than dissipation. Next, we present a self-consistent
+treatment, that properly accounts for time-dependence of the perturber
+potential and circular frequency (memory effect), which we use to examine
+orbital decay in a cored galaxy. We find that the memory effect results in a
+phase of accelerated, super-Chandrasekhar friction before the perturber stalls
+at a critical radius, $R_{\mathrm{crit}}$, in the core (core-stalling). Inside
+of $R_{\mathrm{crit}}$ the torque flips sign, giving rise to dynamical
+buoyancy, which counteracts friction and causes the perturber to stall. This
+phenomenology is consistent with $N$-body simulations, but has thus far eluded
+proper explanation.",2103.05004v1
+2021-03-26,First-order strong-field QED processes including the damping of particles states,"Volkov states are exact solutions of the Dirac equation in the presence of an
+arbitrary plane wave. Volkov states, as well as free photon states, are not
+stable in the presence of the background plane-wave field but ""decay"" as
+electrons/positrons can emit photons and photons can transform into
+electron-positron pairs. By using the solutions of the corresponding
+Schwinger-Dyson equations within the locally-constant field approximation, we
+compute the probabilities of nonlinear single Compton scattering and nonlinear
+Breit-Wheeler pair production by including the effects of the decay of
+electron, positron, and photon states. As a result, we find that the
+probabilities of these processes can be expressed as the integral over the
+light-cone time of the known probabilities valid for stable states per unit of
+light-cone time times a light-cone time-dependent exponential damping function
+for each interacting particle. The exponential function for an incoming
+(outgoing) either electron/positron or photon at each light-cone time
+corresponds to the total probability that either the electron/positron emits a
+photon via nonlinear Compton scattering or the photon transforms into an
+electron-positron pair via nonlinear Breit-Wheeler pair production until that
+light-cone time (from that light-cone time on). It is interesting that the
+exponential damping terms depend not only on the particles momentum but also on
+their spin (for electrons/positrons) and polarization (for photons). This
+additional dependence on the discrete quantum numbers prevents the application
+of the electron/positron spin and photon polarization sum-rules, which
+significantly simplify the computations in the perturbative regime.",2103.14637v1
+2021-04-10,Non-Markovian open quantum system approach to the early universe: I. Damping of gravitational waves by matter,"By revising the application of the open quantum system approach to the early
+universe and extending it to the conditions beyond the Markovian approximation,
+we obtain a new non-Markovian quantum Boltzmann equation. Throughout the paper,
+we also develop an extension of the quantum Boltzmann equation to describe the
+processes that are irreversible at the macroscopic level. This new kinetic
+equation is, in principle, applicable to a wide variety of processes in the
+early universe. For instance, using this equation one can accurately study the
+microscopic influence of a cosmic environment on a system of cosmic background
+photons or stochastic gravitational waves. In this paper, we apply the
+non-Markovian quantum Boltzmann equation to study the damping of gravitational
+waves propagating in a medium consisting of decoupled ultra-relativistic
+neutrinos. For such a system, we study the time evolution of the intensity and
+the polarization of the gravitational waves. It is shown that, in contrast to
+intensity and linear polarization which are damped, the circular polarization
+(V-mode) of the gravitational wave (if present) is amplified by propagating
+through such a medium.",2104.04836v2
+2021-04-19,Giant spin-orbit torque efficiency in all-epitaxial heterostructures,"A large anti-damping spin-obit torque (SOT) efficiency in magnetic
+heterostructures is a prerequisite to realize energy efficient spin torque
+based magnetic memories and logic devices. The efficiency can be characterized
+in terms of the spin-orbit fields generated by anti-damping torques when an
+electric current is passed through the non-magnetic layer. We report a giant
+spin-orbit field of 48.96 (27.50) mT at an applied current density of 1 MAcm-2
+in beta-W interfaced Co60Fe40 (Ni81Fe19)/TiN epitaxial structures due to an
+anti-damping like torque, which results in a magnetization auto-oscillation
+current density as low as 1.68(3.27) MAcm-2. The spin-orbit field value
+increases with decrease of beta-W layer thickness, which affirms that epitaxial
+surface states are responsible for the extraordinary large efficiency. SOT
+induced energy efficient in-plane magnetization switching in large 20x100 um2
+structures has been demonstrated by Kerr microscopy and the findings are
+supported by results from micromagnetic simulations. The observed giant SOT
+efficiencies in the studied all-epitaxial heterostructures are comparable to
+values reported for topological insulators. These results confirm that by
+utilizing epitaxial material combinations an extraordinary large SOT efficiency
+can be achieved using semiconducting industry compatible 5d heavy metals, which
+provides immediate solutions for the realization of energy efficient spin-logic
+devices.",2104.09168v1
+2021-06-10,Constraining extra dimensions using observations of black hole quasi-normal modes,"The presence of extra dimensions generically modify the spacetime geometry of
+a rotating black hole, by adding an additional hair, besides the mass $M$ and
+the angular momentum $J$, known as the `tidal charge' parameter, $\beta$. In a
+braneworld scenario with one extra spatial dimension, the extra dimension is
+expected to manifest itself through -- (a) negative values of $\beta$, and (b)
+modified gravitational perturbations. This in turn would affect the
+quasi-normal modes of rotating black holes. We numerically solve the perturbed
+gravitational field equations using the continued fractions method and
+determine the quasi-normal mode spectra for the braneworld black hole. We find
+that increasingly negative values of $\beta$ correspond to a diminishing
+imaginary part of the quasi-normal mode, or equivalently, an increasing damping
+time. Using the publicly available data of the properties of the remnant black
+hole in the gravitational wave signal GW150914, we check for consistency
+between the predicted values (for a given $\beta$) of the frequency and damping
+time of the least-damped $\ell=2,m=2$ quasi-normal mode and measurements of
+these quantities using other independent techniques. We find that it is highly
+unlikely for the tidal charge, $\beta \lesssim -0.05$, providing a conservative
+limit on the tidal charge parameter. Implications and future directions are
+discussed.",2106.05558v2
+2021-06-24,A Polarizable Water Potential Derived from a Model Electron Density,"A new empirical potential for efficient, large scale molecular dynamics
+simulation of water is presented. The HIPPO (Hydrogen-like Intermolecular
+Polarizable POtential) force field is based upon the model electron density of
+a hydrogen-like atom. This framework is used to derive and parameterize
+individual terms describing charge penetration damped permanent electrostatics,
+damped polarization, charge transfer, anisotropic Pauli repulsion, and damped
+dispersion interactions. Initial parameter values were fit to Symmetry Adapted
+Perturbation Theory (SAPT) energy components for ten water dimer
+configurations, as well as the radial and angular dependence of the canonical
+dimer. The SAPT-based parameters were then systematically refined to extend the
+treatment to water bulk phases. The final HIPPO water model provides a balanced
+representation of a wide variety of properties of gas phase clusters, liquid
+water and ice polymorphs, across a range of temperatures and pressures. This
+water potential yields a rationalization of water structure, dynamics and
+thermodynamics explicitly correlated with an ab initio energy decomposition,
+while providing a level of accuracy comparable or superior to previous
+polarizable atomic multipole force fields. The HIPPO water model serves as a
+cornerstone around which similarly detailed physics-based models can be
+developed for additional molecular species.",2106.13116v3
+2021-07-19,Long term behavior of 2D and 3D non-autonomous random convective Brinkman-Forchheimer equations driven by colored noise,"The long time behavior of Wong-Zakai approximations of 2D as well as 3D
+non-autonomous stochastic convective Brinkman-Forchheimer (CBF) equations with
+non-linear diffusion terms on bounded and unbounded ($\mathbb{R}^d$ for
+$d=2,3$) domains is discussed in this work. To establish the existence of
+random pullback attractors, the concept of asymptotic compactness (AC) is used.
+In bounded domains, AC is proved via compact Sobolev embeddings. In unbounded
+domains, due to the lack of compact embeddings, the ideas of energy equations
+and uniform tail estimates are exploited to prove AC. In the literature, CBF
+equations are also known as \emph{Navier-Stokes equations (NSE) with damping},
+and it is interesting to see that the modification in NSE by linear and
+nonlinear damping provides better results than that available for NSE. The
+presence of linear damping term helps to establish the results in the whole
+domain $\mathbb{R}^d$. The nonlinear damping term supports to obtain better
+results in 3D and also for a large class of nonlinear diffusion terms.
+Moreover, we prove the existence of a unique random pullback attractor for
+stochastic CBF equations with additive white noise. Finally, for additive as
+well as multiplicative noise case, we establish the convergence of solutions
+and upper semicontinuity of random pullback attractors for Wong-Zakai
+approximations of stochastic CBF equations towards the random pullback
+attractors for stochastic CBF equations when correlation time of colored noise
+converges to zero.",2107.08890v1
+2021-07-28,Queue-Channel Capacities with Generalized Amplitude Damping,"The generalized amplitude damping channel (GADC) is considered an important
+model for quantum communications, especially over optical networks. We make two
+salient contributions in this paper apropos of this channel. First, we consider
+a symmetric GAD channel characterized by the parameter $n=1/2,$ and derive its
+exact classical capacity, by constructing a specific induced classical channel.
+We show that the Holevo quantity for the GAD channel equals the Shannon
+capacity of the induced binary symmetric channel, establishing at once the
+capacity result and that the GAD channel capacity can be achieved without the
+use of entanglement at the encoder or joint measurements at the decoder.
+Second, motivated by the inevitable buffering of qubits in quantum networks, we
+consider a generalized amplitude damping \emph{queue-channel} -- that is, a
+setting where qubits suffer a waiting time dependent GAD noise as they wait in
+a buffer to be transmitted. This GAD queue channel is characterized by
+non-i.i.d. noise due to correlated waiting times of consecutive qubits. We
+exploit a conditional independence property in conjunction with additivity of
+the channel model, to obtain a capacity expression for the GAD queue channel in
+terms of the stationary waiting time in the queue. Our results provide useful
+insights towards designing practical quantum communication networks, and
+highlight the need to explicitly model the impact of buffering.",2107.13486v1
+2021-08-13,Nonlinear modal testing of damped structures: Velocity feedback vs. phase resonance,"In recent years, a new method for experimental nonlinear modal analysis has
+been developed, which is based on the extended periodic motion concept. The
+method is well suited to experimentally obtain amplitude-dependent modal
+properties (modal frequency, damping ratio and deflection shape) for strongly
+nonlinear systems. To isolate a nonlinear mode, the negative viscous damping
+term of the extended periodic motion concept is approximated by ensuring phase
+resonance between excitation and response. In this work, an alternative
+approach to isolate a nonlinear mode is developed and analyzed: velocity
+feedback. The accuracy of the extracted modal properties and robustness of
+velocity feedback is first assessed by means of simulated experiments. The two
+approaches phase resonance and velocity feedback are then compared in terms of
+accuracy and experimental implementation effort. To this end, both approaches
+are applied to an experimental specimen, which is a cantilevered beam
+influenced by a strong dry friction nonlinearity. In this work, the discussion
+is limited to single-point excitation. It is shown that a robust implementation
+of velocity feedback requires the measurement of several response signals,
+distributed over the structure. An advantage of velocity feedback is that no
+controller is needed. The accuracy of the modal properties can, however, suffer
+from imperfections of the excitation mechanism such as a phase lag due to
+exciter-structure interactions or gyroscopic forces due to single-point
+excitation.",2108.06189v1
+2021-09-21,Double diffusion structure of logarithmically damped wave equations with a small parameter,"We consider a wave equation with a nonlocal logarithmic damping depending on
+a small parameter $\theta \in (0,1/2)$. This research is a counter part of that
+was initiated by Charao-D'Abbicco-Ikehata considered in [5] for the large
+parameter case $\theta \in (1/2,1)$. We study the Cauchy problem for this model
+in the whole space for the small parameter case, and we obtain an asymptotic
+profile and optimal estimates in time of solutions as time goes to infinity in
+$L^2$-sense. An important discovery in this research is that in the one
+dimensional case, we can present a threshold $\theta^{*} = 1/4$ of the
+parameter $\theta$ such that the solution of the Cauchy problem decays with
+some optimal rate for $\theta \in (0,\theta^{*})$, while the $L^2$-norm of the
+corresponding solution blows up in infinite time for $\theta \in
+[\theta^{*},1/2)$. The former (i.e., $\theta \in (0,\theta^{*})$ case)
+indicates an usual diffusion phenomenon, while the latter (i.e., $\theta \in
+[\theta^{*},1/2)$ case) implies, so to speak, a singular diffusion phenomenon.
+Such a singular diffusion in the one dimensional case is a quite novel
+phenomenon discovered through our new model produced by logarithmic damping
+with a small parameter $\theta$.",2109.09944v2
+2021-09-21,Non-intrusive Balancing Transformation of Highly Stiff Systems with Lightly-damped Impulse Response,"Balanced truncation (BT) is a model reduction method that utilizes a
+coordinate transformation to retain eigen-directions that are highly observable
+and reachable. To address realizability and scalability of BT applied to highly
+stiff and lightly-damped systems, a non-intrusive data-driven method is
+developed for balancing discrete-time systems via the eigensystem realization
+algorithm (ERA). The advantage of ERA for balancing transformation makes
+full-state outputs tractable. Further, ERA enables balancing despite stiffness,
+by eliminating computation of balancing modes and adjoint simulations. As a
+demonstrative example, we create balanced ROMs for a one-dimensional reactive
+flow with pressure forcing, where the stiffness introduced by the chemical
+source term is extreme (condition number $10^{13}$), preventing analytical
+implementation of BT. We investigate the performance of ROMs in prediction of
+dynamics with unseen forcing inputs and demonstrate stability and accuracy of
+balanced ROMs in truly predictive scenarios whereas without ERA, POD-Galerkin
+and Least-squares Petrov-Galerkin projections fail to represent the true
+dynamics. We show that after the initial transients under unit impulse forcing,
+the system undergoes lightly-damped oscillations, which magnifies the influence
+of sampling properties on predictive performance of the balanced ROMs. We
+propose an output domain decomposition approach and couple it with tangential
+interpolation to resolve sharp gradients at reduced computational costs.",2109.10408v2
+2021-10-08,Site characterization at Treasure Island and Delaney Park downhole arrays by heterogeneous data assimilation,"This article extends a recently proposed heterogeneous data assimilation
+technique for site characterization to estimate compression and shear wave
+velocity (Vp and Vs, respectively) and damping at Treasure Island and Delaney
+Park downhole arrays. The adopted method is based on the joint inversion of
+earthquake acceleration time series and experimental surface wave dispersion
+data, and including physical constraints to improve the inverse problem's
+well-posedness. We first use synthetic data at these two sites to refine the
+proposed approach and then apply the refined algorithm to real data sets
+available at the Treasure Island and Delaney Park downhole arrays. The joint
+inversion results show that the estimated Vs and Vp profiles are in very good
+agreement with measured profiles at these two sites. Our synthetic and real
+data experiment results suggest that Vp estimation from inversion at downhole
+arrays can be improved by integrating the water table depth information or the
+higher modes of the Rayleigh wave dispersion data. Depending on the site
+complexity, water table information can also help reduce uncertainties
+associated with damping estimation. In the last part of this article, we
+compare the performance of the inverted profiles to other methods used to
+incorporate spatial variability and wave scattering effects in 1D ground
+response analysis (GRA). The comparisons show that the joint inversion-based Vs
+and Vp profiles and damping ratios estimated in this article can effectively
+integrate the effects of spatial variability and wave scattering into 1D GRAs,
+especially at the Delaney Park downhole array, which is classified as a poorly
+modeled site using traditional 1D GRA.",2110.03849v1
+2021-11-01,On the stochastic nature of Galactic cosmic-ray sources,"The precision measurements of the spectra of cosmic ray nuclei and leptons in
+recent years have revealed the existence of multiple features, such as the
+spectral break at $\sim 300$ GV rigidity seen by PAMELA and AMS-02 and more
+recently confirmed by DAMPE and CALET, the softening in the spectra of H and He
+nuclei at $\sim 10$ TV reported by DAMPE, confirming previous hints by NUCLEON
+and CREAM, a tiny change of slope at $\sim 40$ GeV in the electron spectrum,
+revealed by AMS-02, and the large spectral break at $\sim$ TeV reported by
+indirect (HESS, MAGIC and VERITAS) and direct (DAMPE, CALET) measurements of
+the total (electrons+positrons) lepton spectrum. In all these cases, the
+possibility has been suggested that these features might reflect the occasional
+presence of a local cosmic ray source, inducing a noticeable reshaping of the
+average expected spectra. All these proposals have to face the question of how
+likely it is for such a source to exist, a question that we address here in a
+quantitative way. We study the statistical properties of random distribution of
+sources in space and time, and the effect of the spiral structure of our Galaxy
+for both the spectra of light nuclei (p and He) and leptons (electrons and
+positrons) in different energy regions.",2111.01171v2
+2021-11-09,The In Situ Signature of Cyclotron Resonant Heating,"The dissipation of magnetized turbulence is an important paradigm for
+describing heating and energy transfer in astrophysical environments such as
+the solar corona and wind; however, the specific collisionless processes behind
+dissipation and heating remain relatively unconstrained by measurements. Remote
+sensing observations have suggested the presence of strong temperature
+anisotropy in the solar corona consistent with cyclotron resonant heating. In
+the solar wind, in situ magnetic field measurements reveal the presence of
+cyclotron waves, while measured ion velocity distribution functions have hinted
+at the active presence of cyclotron resonance. Here, we present Parker Solar
+Probe observations that connect the presence of ion-cyclotron waves directly to
+signatures of resonant damping in observed proton-velocity distributions. We
+show that the observed cyclotron wave population coincides with both flattening
+in the phase space distribution predicted by resonant quasilinear diffusion and
+steepening in the turbulent spectra at the ion-cyclotron resonant scale. In
+measured velocity distribution functions where cyclotron resonant flattening is
+weaker, the distributions are nearly uniformly subject to ion-cyclotron wave
+damping rather than emission, indicating that the distributions can damp the
+observed wave population. These results are consistent with active cyclotron
+heating in the solar wind.",2111.05400v2
+2021-11-10,Quantum amplitude damping for solving homogeneous linear differential equations: A noninterferometric algorithm,"In contexts where relevant problems can easily attain configuration spaces of
+enormous sizes, solving Linear Differential Equations (LDEs) can become a hard
+achievement for classical computers; on the other hand, the rise of quantum
+hardware can conceptually enable such high-dimensional problems to be solved
+with a foreseeable number of qubits, whilst also yielding quantum advantage in
+terms of time complexity. Nevertheless, in order to bridge towards experimental
+realizations with several qubits and harvest such potential in a short-term
+basis, one must dispose of efficient quantum algorithms that are compatible
+with near-term projections of state-of-the-art hardware, in terms of both
+techniques and limitations. As the conception of such algorithms is no trivial
+task, insights on new heuristics are welcomed. This work proposes a novel
+approach by using the Quantum Amplitude Damping operation as a resource, in
+order to construct an efficient quantum algorithm for solving homogeneous LDEs.
+As the intended implementation involves performing Amplitude Damping
+exclusively via a simple equivalent quantum circuit, our algorithm shall be
+given by a gate-level quantum circuit (predominantly composed of elementary
+2-qubit gates) and is particularly nonrestrictive in terms of connectivity
+within and between some of its main quantum registers. We show that such an
+open quantum system-inspired circuitry allows for constructing the real
+exponential terms in the solution in a non-interferometric way; we also provide
+a guideline for guaranteeing a lower bound on the probability of success for
+each realization, by exploring the decay properties of the underlying quantum
+operation.",2111.05646v2
+2021-11-27,Rate of Entropy Production in Stochastic Mechanical Systems,"Entropy production in stochastic mechanical systems is examined here with
+strict bounds on its rate. Stochastic mechanical systems include pure
+diffusions in Euclidean space or on Lie groups, as well as systems evolving on
+phase space for which the fluctuation-dissipation theorem applies, i.e.,
+return-to-equilibrium processes. Two separate ways for ensembles of such
+mechanical systems forced by noise to reach equilibrium are examined here.
+First, a restorative potential and damping can be applied, leading to a
+classical return-to-equilibrium process wherein energy taken out by damping can
+balance the energy going in from the noise. Second, the process evolves on a
+compact configuration space (such as random walks on spheres, torsion angles in
+chain molecules, and rotational Brownian motion) lead to long-time solutions
+that are constant over the configuration space, regardless of whether or not
+damping and random forcing balance. This is a kind of potential-free
+equilibrium distribution resulting from topological constraints. Inertial and
+noninertial (kinematic) systems are considered. These systems can consist of
+unconstrained particles or more complex systems with constraints, such as
+rigid-bodies or linkages. These more complicated systems evolve on Lie groups
+and model phenomena such as rotational Brownian motion and nonholonomic robotic
+systems. In all cases, it is shown that the rate of entropy production is
+closely related to the appropriate concept of Fisher information matrix of the
+probability density defined by the Fokker-Planck equation. Classical results
+from information theory are then repurposed to provide computable bounds on the
+rate of entropy production in stochastic mechanical systems.",2111.13930v1
+2021-12-22,Strong Stabilization of a 3D Potential Flow via a Weakly Damped von Karman Plate,"The elimination of aeroelastic instability (resulting in sustained
+oscillations of bridges, buildings, airfoils) is a central engineering and
+design issue. Mathematically, this translates to strong asymptotic
+stabilization of a 3D flow by a 2D elastic structure. The stabilization
+(convergence to the stationary set) of a aerodynamic wave-plate model is
+established here. A 3D potential flow on the half-space has a spatially-bounded
+von Karman plate embedded in the boundary. The physical model, then, is a
+Neumann wave equation with low regularity of coupling conditions. Motivated on
+empirical observations, we examine if intrinsic panel damping can stabilize the
+subsonic flow-plate system to a stationary point. Several partial results have
+been established through partial regularization of the model. Without doing so,
+classical approaches attempting to treat the given wave boundary data have
+fallen short, owing to the failure of the Lopatinski condition (in the sense of
+Kreiss, Sakamoto) and the associated regularity defect of the hyperbolic
+Neumann mapping. Here, we operate on the panel model as in the engineering
+literature with no regularization or modifications; we completely resolve the
+question of stability by demonstrating that weak plate damping strongly
+stabilizes system trajectories. This is accomplished by microlocalizing the
+wave data (given by the plate) and observing an ""anisotropic"" a microlocal
+compensation by the plate dynamics precisely where the regularity of the 3D
+wave is compromsed (in the characteristic sector). Several additional stability
+results for both wave and plate subsystems are established to ""push"" strong
+stability of the plate onto the flow.",2112.12208v1
+2021-12-28,Kinetic investigation of the planar Multipole Resonance Probe under arbitrary pressure,"Active plasma resonance spectroscopy (APRS) refers to a class of plasma
+diagnostic methods that use the ability of plasma to resonate at or near the
+electron plasma frequency for diagnostic purposes. The planar multipole
+resonance probe (pMRP) is an optimized realization of APRS. It has a
+non-invasive structure and allows simultaneous measurement of the electron
+density, electron temperature, and electron-neutral collision frequency.
+Previous work has investigated the pMRP through the Drude model and
+collision-less kinetic model. The Drude model misses important kinetic effects
+such as collision-less kinetic damping. The collision-less kinetic model is
+able to capture pure kinetic effects. However, it is only applicable to
+low-pressure plasma. To further study the behavior of the pMRP, we develop a
+collisional kinetic model in this paper, which applies to arbitrary pressure.
+In this model, the kinetic equation is coupled to the Poisson equation under
+the electrostatic approximation. The real part of the general admittance is
+calculated to describe the spectral response of the probe-plasma system. Both
+collision-less kinetic damping and collisional damping appear in the spectrum.
+This model provides a possibility to calculate the electron density, electron
+temperature, and electron-neutral collision frequency from the measurements.",2112.14190v2
+2021-12-28,Metadamping in inertially amplified metamaterials: Trade-off between spatial attenuation and temporal attenuation,"Metadamping is the phenomenon of either enhanced or diminished intrinsic
+dissipation in a material stemming from the material's internal structural
+dynamics. It has been previously shown that a locally resonant elastic
+metamaterial may be designed to exhibit higher or lower dissipation compared to
+a statically equivalent phononic crystal with the same amount of prescribed
+damping. Here we reveal that even further dissipation, or alternatively further
+reduction of loss, may be reached in an inertially amplified metamaterial that
+is also statically equivalent and has the same amount of prescribed damping.
+This is demonstrated by a passive configuration whereby an attenuation peak is
+generated by the motion of a mass supported by an inclined lever arm. We
+further show that by coupling this inertially amplified attenuation peak with
+that of a local resonance attenuation peak, a trade-off between the intensity
+of spatial attenuation versus temporal attenuation is realized for a range of
+the inclination angles. Design for performance along this trade-off is
+therefore possible by adjustment of the lever angle. These findings open the
+way for highly expanding the Ashby space for stiffness-damping capacity or
+stiffness-spatial attenuation capacity through design of the internal structure
+of materials.",2112.14322v1
+2022-01-10,Tidal erasure of stellar obliquities constrains the timing of hot Jupiter formation,"Stars with hot Jupiters sometimes have high obliquities, which are possible
+relics of hot Jupiter formation. Based on the characteristics of systems with
+and without high obliquities, it is suspected that obliquities are tidally
+damped when the star has a thick convective envelope, as is the case for
+main-sequence stars cooler than ~6100K, and the orbit is within ~8 stellar
+radii. A promising theory for tidal obliquity damping is the dissipation of
+inertial waves within the star's convective envelope. Here, we consider the
+implications of this theory for the timing of hot Jupiter formation.
+Specifically, hot stars that currently lack a convective envelope possess one
+during their pre-main sequence. We find that hot Jupiters orbiting within a
+critical distance of ~0.02au from a misaligned main-sequence star lacking a
+thick convective envelope must have acquired their tight orbits after a few
+tens of millions of years in order to have retained their obliquities
+throughout the pre-main-sequence. There are 4 known systems for which this
+argument applies--XO-3b, Corot-3b, WASP-14b, and WASP-121b--subject to
+uncertainties surrounding inertial wave dissipation. Moreover, we conclude that
+a recently-identified overabundance of near-polar hot Jupiters is unlikely
+sculpted by tides, instead reflecting their primordial configuration. Finally,
+hot Jupiters arriving around cool stars after a few 100s of millions of years
+likely find the host star rotating too slowly for efficient obliquity damping.
+We predict that the critical effective temperature separating aligned and
+misaligned stars should vary with metallicity, from 6300K to 6000K as [Fe/H]
+varies from -0.3 to +0.3.",2201.03653v1
+2022-01-22,Examining AGN UV/optical Variability Beyond the Simple Damped Random Walk,"We present damped harmonic oscillator (DHO) light-curve modeling for a sample
+of 12,714 spectroscopically confirmed quasars in the Sloan Digital Sky Survey
+Stripe 82 region. DHO is a second-order continuous-time autoregressive
+moving-average (CARMA) process, which can be fully described using four
+independent parameters: a natural oscillation frequency ($\omega_{0}$), a
+damping ratio ($\xi$), a characteristic perturbation timescale
+($\tau_{\mathrm{perturb}}$), and an amplitude for the perturbing white noise
+($\sigma_{\mathrm{\epsilon}}$). The asymptotic variability amplitude of a DHO
+process is quantified by $\sigma_{\mathrm{DHO}}$ -- a function of $\omega_{0}$,
+$\xi$, $\tau_{\mathrm{perturb}}$, and $\sigma_{\mathrm{\epsilon}}$. We find
+that both $\tau_{\mathrm{perturb}}$ and $\sigma_{\mathrm{\epsilon}}$ follow
+different dependencies with rest-frame wavelength ($\lambda_{\mathrm{RF}}$) on
+either side of 2500 \AA, whereas $\sigma_{\mathrm{DHO}}$ follows a single
+power-law relation with $\lambda_{\mathrm{RF}}$. After correcting for
+wavelength dependence, $\sigma_{\mathrm{DHO}}$ exhibits anti-correlations with
+both the Eddington ratio and the black hole mass, while
+$\tau_{\mathrm{perturb}}$ -- with a typical value of days in the rest-frame --
+shows an anti-correlation with the bolometric luminosity. Modeling AGN
+variability as a DHO offers more insight into the workings of accretion disks
+close to the supermassive black holes (SMBHs) at the center of AGN. The newly
+discovered short-term variability (characterized by $\tau_{\mathrm{perturb}}$
+and $\sigma_{\mathrm{\epsilon}}$) and its correlation with bolometric
+luminosity pave the way for new algorithms that will derive fundamental
+properties (e.g., Eddington ratio) of AGN using photometric data alone.",2201.08943v2
+2022-04-20,Ferrimagnet GdFeCo characterization for spin-orbitronics: large field-like and damping-like torques,"Spintronics is showing promising results in the search for new materials and
+effects to reduce energy consumption in information technology. Among these
+materials, ferrimagnets are of special interest, since they can produce large
+spin currents that trigger the magnetization dynamics of adjacent layers or
+even their own magnetization. Here, we present a study of the generation of
+spin current by GdFeCo in a GdFeCo/Cu/NiFe trilayer where the FeCo sublattice
+magnetization is dominant at room temperature. Magnetic properties such as the
+saturation magnetization are deduced from magnetometry measurements while
+damping constant is estimated from spin-torque ferromagnetic resonance
+(ST-FMR). We show that the overall damping-like (DL) and field-like (FL)
+effective fields as well as the associated spin Hall angles can be reliably
+obtained by performing the dependence of ST-FMR by an added dc current. The sum
+of the spin Hall angles for both the spin Hall effect (SHE) and the spin
+anomalous Hall effect (SAHE) symmetries are: $\theta_{DL}^{SAHE} +
+\theta_{DL}^{SHE}=-0.15 \pm 0.05$ and $\theta_{FL}^{SAHE} +
+\theta_{FL}^{SHE}=0.026 \pm 0.005$. From the symmetry of ST-FMR signals we find
+that $\theta_{DL}^{SHE}$ is positive and dominated by the negative
+$\theta_{DL}^{SAHE}$. The present study paves the way for tuning the different
+symmetries in spin conversion in highly efficient ferrimagnetic systems.",2204.09776v1
+2022-04-21,Characterizing the $γ$-Ray Variability of Active Galactic Nuclei with Stochastic Process Method,"The $\gamma$-ray astronomy in time domain has been by now progressed further
+as the variabilities of Active Galactic Nuclei (AGNs) on different timescales
+have been reported a lot. We study the $\gamma$-ray variabilities of 23 jetted
+AGNs through applying a stochastic process method to the ~12.7 yr long-term
+light curve (LC) obtained by Fermi-Large Area Telescope (Fermi-LAT). In this
+method, the stochastically driven damped simple harmonic oscillator (SHO) and
+the damped random walk (DRW) models are used to model the long-term LCs. Our
+results show that the long-term variabilities of 23 AGNs can be characterized
+well by both SHO and DRW models. However, the SHO model is restricted in the
+over-damped mode and the parameters are poorly constrained. The SHO power
+spectral densities (PSDs) are same as the typical DRW PSD. In the plot of the
+rest-frame timescale that corresponds to the broken frequency in the PSD versus
+black hole mass, the intrinsic $\gamma$-ray characteristic timescales of 23
+AGNs occupy almost the same space with the optical variability timescales
+obtained from the accretion disk emission. This suggests a connection between
+the jet and the accretion disk. Same as the optical variability of AGN
+accretion disk, the $\gamma$-ray timescale is also consistent with the thermal
+timescale caused by the thermal instability in the standard accretion disk of
+AGN.",2204.09987v1
+2022-04-29,A fast point charge interacting with the screened Vlasov-Poisson system,"We consider the long-time behavior of a fast, charged particle interacting
+with an initially spatially homogeneous background plasma. The background is
+modeled by the screened Vlasov-Poisson equations, whereas the interaction
+potential of the point charge is assumed to be smooth. We rigorously prove the
+validity of the \emph{stopping power theory} in physics, which predicts a
+decrease of the velocity $V(t)$ of the point charge given by $\dot{V} \sim
+-|V|^{-3} V$, a formula that goes back to Bohr (1915). Our result holds for all
+initial velocities larger than a threshold value that is larger than the
+velocity of all background particles and remains valid until (i) the particle
+slows down to the threshold velocity, or (ii) the time is exponentially long
+compared to the velocity of the point charge. The long-time behavior of this
+coupled system is related to the question of Landau damping which has remained
+open in this setting so far. Contrary to other results in nonlinear Landau
+damping, the long-time behavior of the system is driven by the non-trivial
+electric field of the plasma, and the damping only occurs in regions that the
+point charge has already passed.",2205.00035v2
+2022-05-06,"Discovery of a coherent, wave-like velocity pattern for the Radcliffe Wave","Recently studies discovered that part of the Gould Belt belongs to a 2.7
+kpc-long {coherent, thin} wave consisting of a chain of clouds, where a damped
+undulation pattern has been identified from the spatial arrangement of the
+clouds. We use the proper motions of Young Stellar Objects (YSOs) anchored
+inside the clouds to study the kinematic structure of the Radcliffe Wave in
+terms of $v_z$, and identify a damped, wave-like pattern from the $v_z$ space,
+which we call ""velocity undulation"". We propose a new formalism based on the
+Ensemble Empirical Mode Decomposition (EEMD) to determine the amplitude,
+period, and phase of the undulation pattern, and find that the spatial and the
+velocity undulation share an almost identical spatial frequency of about 1.5
+kpc, and both are damped when measured from one side to the other. Measured for
+the first cycle, they exhibit a phase difference of around $2\pi/3$. The
+structure is oscillating around the midplane of the Milky Way disk with an
+amplitude of $\sim\,130\,\pm\,20\,\rm pc$. The vertical extent of the Radcliffe
+Wave exceeds the thickness of the molecular disk, suggesting that the
+undulation of the undulation signature might originate from a perturbation,
+e.g. the passage of a dwarf galaxy.",2205.03218v1
+2022-05-17,Resolving the HI in Damped Lyman-α systems that power star-formation,"Reservoirs of dense atomic gas (primarily hydrogen), contain approximately 90
+percent of the neutral gas at a redshift of 3, and contribute to 2-3 percent of
+the total baryons in the Universe. These damped Lyman-${\alpha}$ systems (so
+called because they absorb Lyman-${\alpha}$ photons from within and from
+background sources) have been studied for decades, but only through absorption
+lines present in the spectra of background quasars and gamma-ray bursts. Such
+pencil beams do not constrain the physical extent of the systems. Here, we
+report integral-field spectroscopy of a bright, gravitationally lensed galaxy
+at a redshift of 2.7 with two foreground damped Lyman-${\alpha}$ systems. These
+systems are $>$ 238 $kpc^2$ in extent, with column densities of neutral
+hydrogen varying by more than an order of magnitude on $<$ 3 kpc-scales. The
+mean column densities are $10^{20.46}$ - $10^{20.84} cm^{-2}$ and the total
+masses are $> 5.5 \times 10^{8}$ - $1.4 \times 10^{9} M_{\odot}$, showing that
+they contain the necessary fuel for the next generation of star formation,
+consistent with relatively massive, low-luminosity primeval galaxies at
+redshifts $>$ 2.",2205.08554v1
+2022-05-21,Accuracy of one-dimensional approximation in neutron star quasi-normal modes,"Since the eigenfrequency of gravitational waves from cold neutron stars
+becomes a complex number, where the real and imaginary parts respectively
+correspond to an oscillation frequency and damping rate, one has to somehow
+solve the eigenvalue problem concerning the eigenvalue in two-dimensional
+parameter space. To avoid this bother, one sometimes adopts an approximation,
+where the eigenvalue is in one-dimensional parameter space. In this study,
+first, we show the accuracy of the zero-damping approximation, which is one of
+the one-dimensional approximations, for the fundamental and 1st pressure modes.
+But, this approximation is not applicable to the spacetime mode, because the
+damping rate of the spacetime mode is generally comparable to the oscillation
+frequency. Nevertheless, we find the empirical relation for the ratio of the
+imaginary part to the real part of the eigenfrequency, which is expressed as a
+function of the steller compactness almost independently of the adopted
+equations of state for neutron star matter. Adopting this empirical relation,
+one can express the eigenfrequency in terms of just the real part, i.e., the
+problem to solve becomes an eigenvalue problem with a one-dimensional
+eigenvalue. Then, we find that the frequencies are estimated with good accuracy
+even with such approximations even for the 1st spacetime mode.",2205.10523v1
+2022-06-02,Proximity of exoplanets to first-order mean-motion resonances,"Planetary formation theories and, more specifically, migration models predict
+that planets can be captured in mean-motion resonances (MMRs) during the disc
+phase. The distribution of period ratios between adjacent planets shows an
+accumulation in the vicinity of the resonance, which is not centred on the
+nominal resonance but instead presents an offset slightly exterior to it. Here
+we extend on previous works by thoroughly exploring the effect of different
+disc and planet parameters on the resonance offset during the disc migration
+phase. The dynamical study is carried out for several first-order MMRs and for
+both low-mass Earth-like planets undergoing type-I migration and giant planets
+evolving under type-II migration. We find that the offset varies with time
+during the migration of the two-planet system along the apsidal corotation
+resonance family. The departure from the nominal resonance increases for higher
+planetary masses and stronger eccentricity damping. In the Earth to super-Earth
+regime, we find offset values in agreement with the observations when using a
+sophisticated modelling for the planet-disc interactions, where the damping
+timescale depends on the eccentricity. This dependence causes a feedback which
+induces an increase of the resonance offsets. Regarding giant planets, the
+offsets of detected planet pairs are well reproduced with a classical
+$K$-factor prescription for the planet-disc interactions when the eccentricity
+damping rate remains low to moderate. In both regimes, eccentricities are in
+agreement with the observations too. As a result, planet-disc interactions
+provide a generic channel to generate the offsets found in the observations.",2206.00943v1
+2022-06-03,Dynamical Instability in Multi-Orbiter Systems with Gas Friction,"Closely-packed multi-planet systems are known to experience dynamical
+instability if the spacings between the planets are too small. Such instability
+can be tempered by the frictional forces acting on the planets from gaseous
+discs. A similar situation applies to stellar-mass black holes embedded in AGN
+discs around supermassive black holes. In this paper, we use $N$-body
+integrations to evaluate how the frictional damping of orbital eccentricity
+affects the growth of dynamical instability for a wide range of planetary
+spacing and planet-to-star mass ratios. We find that the stability of a system
+depends on the damping timescale $\tau$ relative to the zero-friction
+instability growth timescale $t_{\rm inst}$. In a two-planet system, the
+frictional damping can stabilise the dynamical evolution if $t_{\rm
+inst}\gtrsim\tau$. With three planets, $t_{\rm inst} \gtrsim 10\tau - 100\tau$
+is needed for stabilisation. When the separations between the planetary orbits
+are sufficiently small, $t_{\rm inst}$ can be less than the synodic period
+between the planets, which makes frictional stabilisation unlikely to occur. As
+the orbital spacing increases, the instability timescale tends to grow
+exponentially on average, but it can vary by a few orders of magnitude
+depending on the initial orbital phases of the planets. In general, the stable
+region (at large orbital spacings) and unstable region (at small orbital
+spacings) are separated by a transition zone, in which the (in)stability of the
+system is not guaranteed. We also devise a linear map to analyse the dynamical
+instability of the ""planet + test-mass"" system, and we find qualitatively
+similar results to the $N$-body simulations.",2206.01755v1
+2022-08-15,Nonperturbative approach to interfacial spin-orbit torques induced by Rashba effect,"Current-induced spin-orbit torque (SOT) in normal metal/ferromagnet (NM/FM)
+bilayers bears great promise for technological applications, but the
+microscopic origin of purely interfacial SOTs in ultra-thin systems is not yet
+fully understood. Here, we show that a linear response theory with a
+nonperturbative treatment of spin-dependent interactions and impurity
+scattering potential predicts damping-like SOTs that are strictly absent in
+perturbative approaches. The technique is applied to a two-dimensional
+Rashba-coupled ferromagnet (the paradigmatic model of a NM/FM interface), where
+higher-order scattering processes encoding skew scattering from nonmagnetic
+impurities allow for current-induced spin polarization with nonzero components
+along all spatial directions. This is in stark contrast to previous results of
+perturbative methods (neglecting skew scattering), which predict a coplanar
+spin-polarization locked perpendicular to the charge current as a result of
+conventional Rashba-Edelstein effect. Furthermore, the angular dependence of
+ensuing SOTs and their dependence upon the scattering potential strength is
+analysed numerically. Simple analytic expressions for the
+spin-density--charge-current response function, and related SOT efficiencies,
+are obtained in the weak scattering limit. We find that the extrinsic
+damping-like torques driven by impurity scattering reaches efficiencies of up
+to 7% of the field-like (Rashba-Edelstein) torque. Our microscopic theory shows
+that bulk phenomena, such as the spin Hall effect, are not a necessity in the
+generation of the damping-like SOTs of the type observed in experiments on
+ultra-thin systems.",2208.07296v1
+2022-08-22,Plasma heating and nanoflare caused by slow-mode wave in a coronal loop,"We present a detailed analysis of a reflecting intensity perturbation in a
+large coronal loop that appeared as sloshing oscillation and lasted for at
+least one and a half periods. The perturbation is initiated by a microflare at
+one footpoint of the loop, propagates along the loop and is eventually
+reflected at the remote footpoint where significant brightenings are observed
+in all the AIA extreme-ultraviolet (EUV) channels. This unique observation
+provides us with the opportunity to better understand not only the thermal
+properties and damping mechanisms of the sloshing oscillation, but also the
+energy transfer at the remote footpoint. Based on differential emission
+measures (DEM) analysis and the technique of coronal seismology, we find that
+1) the calculated local sound speed is consistent with the observed propagation
+speed of the perturbation during the oscillation, which is suggestive of a slow
+magnetoacoustic wave; 2) thermal conduction is the major damping mechanism of
+the wave but additional damping mechanism such as anomalous enhancement of
+compressive viscosity or wave leakage is also required to account for the rapid
+decay of the observed waves; 3) the wave produced a nanoflare at the remote
+footpoint, with a peak thermal energy of $\thicksim10^{24}-10^{25}$ erg. This
+work provides a consistent picture of the magnetoacoustic wave propagation and
+reflection in a coronal loop, and reports the first solid evidence of a
+wave-induced nanoflare. The results reveal new clues for further simulation
+studies and may help solving the coronal heating problem.",2208.10029v1
+2022-09-07,AlH lines in the blue spectrum of Proxima Centauri,"The recently-computed ExoMol line lists for isotopologues of AlH are used to
+analyse the blue spectrum (4000-4500 {\AA}) of Proxima Cen (M5.5 V). Comparison
+of the observed and computed spectra enables the identification of a large
+number of 27AlH lines of the A1{\Pi} - X1{\Sigma}+ band system: the spectral
+range covering 1-0, 0-0 and 1-1 bands is dominated by clearly resolved AlH
+lines. We reveal the diffuse nature of transitions close to the dissociation
+limit which appears in the form of increasingly wider(up to 5 {\AA}) and
+shallower (up to the continuum confusion limit) AlH line profiles. The
+predicted wavelengths of AlH diffuse lines are systematically displaced. The
+effect broadening by pre-dissociation states on the line profiles is included
+by increasing the radiative damping rate by up to 5 orders of magnitude. We
+determine empirical values of damping rates for a number of the clean 0-0
+Q-branch transitions by comparing the observed and synthetic stellar spectra.
+We find excellent agreement between our damping rates and lifetimes available
+in the literature. A comparison of 27Al1H ExoMol and REALH spectra shows that
+the observed spectrum is better described by the ExoMol line list. A search for
+26Al1H lines in the Proxima Cen spectrum does not reveal any notable features;
+giving an upper limit of 27Al1H/26Al1H {>} 100.",2209.03037v2
+2022-09-19,Semi-implicit Integration and Data-Driven Model Order Reduction in Structural Dynamics with Hysteresis,"Structural damping is known to be approximately rate-independent in many
+cases. Popular models for rate-independent dissipation are hysteresis models;
+and a highly popular hysteresis model is the Bouc-Wen model. If such hysteretic
+dissipation is incorporated in a refined finite element model, then the
+mathematical model includes the usual structural dynamics equations along with
+nonlinear nonsmooth ordinary differential equations for a large number of
+internal hysteretic states at Gauss points, to be used within the virtual work
+calculation for dissipation. For such systems, numerical integration becomes
+difficult due to both the distributed non-analytic nonlinearity of hysteresis
+as well as the very high natural frequencies in the finite element model. Here
+we offer two contributions. First, we present a simple semi-implicit
+integration approach where the structural part is handled implicitly based on
+the work of Pich\'e, and where the hysteretic part is handled explicitly. A
+cantilever beam example is solved in detail using high mesh refinement.
+Convergence is good for lower damping and a smoother hysteresis loop. For a
+less smooth hysteresis loop and/or higher damping, convergence is observed to
+be roughly linear on average. Encouragingly, the time step needed for stability
+is much larger than the time period of the highest natural frequency of the
+structural model. Subsequently, data from several simulations conducted using
+the above semi-implicit method are used to construct reduced order models of
+the system, where the structural dynamics is projected onto a small number of
+modes and the number of hysteretic states is reduced significantly as well.
+Convergence studies of error against the number of retained hysteretic states
+show very good results.",2209.08765v2
+2022-09-21,Performance enhancement of a spin-wave-based reservoir computing system utilizing different physical conditions,"The authors have numerically studied how to enhance reservoir computing
+performance by thoroughly extracting their spin-wave device potential for
+higher-dimensional information generation. The reservoir device has a 1-input
+exciter and 120-output detectors on the top of a continuous magnetic garnet
+film for spin-wave transmission. For various nonlinear and fading-memory
+dynamic phenomena distributing in the film space, small in-plane magnetic
+fields were used to prepare stripe domain structures and various damping
+constants at the film sides and bottom were explored. The ferromagnetic
+resonant frequency and relaxation time of spin precession clearly characterized
+the change in spin dynamics with the magnetic field and damping constant. The
+common input signal for reservoir computing was a 1 GHz cosine wave with random
+6-valued amplitude modulation. A basic 120-dimensional reservoir output vector
+was obtained from time-series signals at the 120 output detectors under each of
+the three magnetic field conditions. Then, 240- and 360-dimensional reservoir
+output vectors were also constructed by concatenating two and three basic ones,
+respectively. In nonlinear autoregressive moving average (NARMA) prediction
+tasks, the computational performance was enhanced as the dimension of the
+reservoir output vector becomes higher and a significantly low prediction error
+was achieved for the 10th-order NARMA using the 360-dimensional vector and
+optimum damping constant. The results are clear evidence that the collection of
+diverse output signals efficiently increases the dimensionality effective for
+reservoir computing, i.e., reservoir-state richness. This paper demonstrates
+that performance enhancement through various configuration settings is a
+practical approach for on-chip reservoir computing devices with small numbers
+of real output nodes.",2209.10123v1
+2022-10-02,Reduction in turbulence-induced non-linear dynamic vibration using tuned liquid damper (TLD),"In the present research work, an attempt is made to develop a coupled
+non-linear turbulence-structure-damper model in a finite volume-finite
+difference (FV-FD) framework. Tuned liquid damper (TLD) is used as the
+additional damping system along with inherent structural damping. Real-time
+simulation of flow-excited bridge box girder or chimney section and the
+vibration reduction using TLD can be performed using the developed model. The
+turbulent flow field around a structure is modeled using an OpenFOAM transient
+PISO solver, and the time-varying drag force is calculated. This force perturbs
+the structure, causing the sloshing phenomena of the attached TLD, modeled
+using shallow depth approximation, damping the flow-induced vibration of the
+structure. The structural motion with and without the attached TLD is modeled
+involving the FD-based Newmark-Beta method using in-house MATLAB codes. The TLD
+is tuned with the vortex-shedding frequency of the low-Reynolds number flows,
+and it is found to be reducing the structural excitation significantly. On the
+other hand, the high-Reynolds number turbulent flow exhibits a broadband
+excitation, for which by tuning the TLD with few frequencies obtained through
+investigations, a good reduction in vibration is observed.",2210.00428v3
+2022-10-19,Energy Dissipation in Synchronous Binary Asteroids,"Synchronous binary asteroids can experience libration about their
+tidally-locked equilibrium, which will result in energy dissipation. This is an
+important topic to the Asteroid Impact and Deflection Assessment, where
+excitation caused by the DART kinetic impact in the Didymos binary asteroid
+system may be reduced through dissipation before Hera arrives to survey the
+effects of the impact. We develop a numeric model for energy dissipation in
+binary asteroids to explore how different system configurations affect the rate
+of energy dissipation. We find tumbling within the synchronous state eliminates
+a systematic trend in libration damping on short timescales (several years),
+but not over long times (hundreds of years) depending on the material
+conditions. Furthermore, damping of libration, eccentricity, and fluctuations
+in the semimajor axis are primarily dependent on the stiffness of the
+secondary, whereas the semimajor axis secular expansion rate is dictated by the
+stiffness of the primary, as expected. Systems experiencing stable planar
+libration in the secondary can see a noticeable reduction in libration
+amplitude after only a few years depending on the stiffness of the secondary,
+and thus dissipation should be considered during Hera's survey of Didymos. For
+a very dissipative secondary undergoing stable libration, Hera may be able to
+calculate the rate of libration damping in Dimorphos and therefore constrain
+its tidal parameters.",2210.10877v1
+2022-11-14,Heavily Damped Precessional Switching with Very Low Write-error Rate in Elliptical-cylinder Magnetic Tunnel Junction,"Voltage-induced dynamic switching in magnetic tunnel junctions (MTJs) is a
+writing technique for voltage-controlled magnetoresistive random access memory
+(VCMRAM), which is expected to be an ultimate non-volatile memory with
+ultra-low power consumption. In conventional dynamic switching, the width of
+sub-nanosecond write voltage pulses must be precisely controlled to achieve a
+sufficiently low write-error rate (WER). This very narrow tolerance of pulse
+width is the biggest technical difficulty in developing VCMRAM. Heavily damped
+precessional switching is a writing scheme for VCMRAM with a substantially high
+tolerance of pulse width although the minimum WER has been much higher than
+that of conventional dynamic switching with an optimum pulse width. In this
+study, we theoretically investigate the effect of MTJ shape and the direction
+of the applied magnetic field on the WER of heavily damped precessional
+switching. The results show that the WER in elliptical-cylinder MTJ can be
+several orders of magnitude smaller than that in usual circular-cylinder MTJ
+when the external magnetic field is applied parallel to the minor axis of the
+ellipse. The reduction in WER is due to the fact that the demagnetization field
+narrows the component of the magnetization distribution perpendicular to the
+plane direction immediately before the voltage is applied.",2211.07148v1
+2022-11-19,Regularity to Timoshenko's System with Thermoelasticity of Type III with Fractional Damping,"The article, presents the study of the regularity of two thermoelastic beam
+systems defined by the Timoshenko beam model coupled with the heat conduction
+of Green-Naghdiy theory of type III, both mathematical models are
+differentiated by their coupling terms that arise as a consequence of the
+constitutive laws initially considered. The systems presented in this work have
+3 fractional dampings: $\mu_1(-\Delta)^\tau \phi_t$, $\mu_2(-\Delta)^\sigma
+\psi_t$ and $K(-\Delta)^\xi \theta_t$, where $\phi,\psi$ and $\theta$ are
+transverse displacement, rotation angle and empirical temperature of the bean
+respectively and the parameters $(\tau,\sigma,\xi)\in [0,1]^3$. It is noted
+that for values 0 and 1 of the parameter $\tau$, the so-called frictional or
+viscous damping will be faced, respectively. The main contribution of this
+article is to show that the corresponding semigroup
+$S_i(t)=e^{\mathcal{B}_it}$, with $i=1,2$, is of Gevrey class
+$s>\frac{r+1}{2r}$ for $r=\min \{\tau,\sigma,\xi\}$ for all
+  $(\tau,\sigma,\xi )\in R_{CG}:= (0, 1)^3$. It is also showed that
+$S_1(t)=e^{\mathcal{B}_1t}$ is analytic in the region $R_{A_1}:=\{(\tau,\sigma,
+\xi )\in [\frac{1}{2},1]^3\}$ and $S_2(t)=e^{\mathcal{B}_2t}$ is analytic in
+the region $R_{A_2}:=\{(\tau,\sigma, \xi )\in [\frac{1}{2},1]^3/ \tau=\xi\}$.",2211.10816v2
+2022-11-28,Exciting the TTV Phases of Resonant Sub-Neptunes,"There are excesses of sub-Neptunes just wide of period commensurabilities
+like the 3:2 and 2:1, and corresponding deficits narrow of them. Any theory
+that explains this period ratio structure must also explain the strong transit
+timing variations (TTVs) observed near resonance. Besides an amplitude and a
+period, a sinusoidal TTV has a phase. Often overlooked, TTV phases are
+effectively integration constants, encoding information about initial
+conditions or the environment. Many TTVs near resonance exhibit non-zero
+phases. This observation is surprising because dissipative processes that
+capture planets into resonance also damp TTV phases to zero. We show how both
+the period ratio structure and the non-zero TTV phases can be reproduced if
+pairs of sub-Neptunes capture into resonance in a gas disc while accompanied by
+a third eccentric non-resonant body. Convergent migration and eccentricity
+damping by the disc drives pairs to orbital period ratios wide of
+commensurability; then, after the disc clears, secular forcing by the third
+body phase-shifts the TTVs. The scenario predicts that resonant planets are
+apsidally aligned and possess eccentricities up to an order of magnitude larger
+than previously thought.",2211.15701v2
+2022-12-04,An Unsupervised Machine Learning Method for Electron--Proton Discrimination of the DAMPE Experiment,"Galactic cosmic rays are mostly made up of energetic nuclei, with less than
+$1\%$ of electrons (and positrons). Precise measurement of the electron and
+positron component requires a very efficient method to reject the nuclei
+background, mainly protons. In this work, we develop an unsupervised machine
+learning method to identify electrons and positrons from cosmic ray protons for
+the Dark Matter Particle Explorer (DAMPE) experiment. Compared with the
+supervised learning method used in the DAMPE experiment, this unsupervised
+method relies solely on real data except for the background estimation process.
+As a result, it could effectively reduce the uncertainties from simulations.
+For three energy ranges of electrons and positrons, 80--128 GeV, 350--700 GeV,
+and 2--5 TeV, the residual background fractions in the electron sample are
+found to be about (0.45 $\pm$ 0.02)$\%$, (0.52 $\pm$ 0.04)$\%$, and (10.55
+$\pm$ 1.80)$\%$, and the background rejection power is about (6.21 $\pm$ 0.03)
+$\times$ $10^4$, (9.03 $\pm$ 0.05) $\times$ $10^4$, and (3.06 $\pm$ 0.32)
+$\times$ $10^4$, respectively. This method gives a higher background rejection
+power in all energy ranges than the traditional morphological parameterization
+method and reaches comparable background rejection performance compared with
+supervised machine learning~methods.",2212.01843v1
+2022-12-05,Stability of Cnoidal Waves for the Damped Nonlinear Schrödinger Equation,"We consider the cubic nonlinear Schr\""odinger (NLS) equation with a linear
+damping on the one dimensional torus and we investigate the stability of some
+solitary wave profiles within the dissipative dynamics. The undamped cubic NLS
+equation is well known to admit a family of periodic waves given by Jacobi
+elliptic functions of cnoidal type. We show that the family of cnoidal waves is
+orbitally stable. More precisely, by considering a sufficiently small
+perturbation of a given cnoidal wave at initial time, the evolution will always
+remain close (up to symmetries of the equation) to the cnoidal wave whose mass
+is modulated according to the dissipative dynamics. This result extends the
+concept of orbital stability to this non-Hamiltonian evolution. Since cnoidal
+waves are not exact solutions to the damped NLS, the perturbation is forced
+away from the family of solitary wave profiles. In order to control this
+secular growth of the error, we find a first order approximation of the
+solitary wave that takes into account the dissipative term. Then we use a
+suitable, exponentially decreasing Lyapunov functional that controls the
+$H^1$-norm of the perturbation around the approximated solitons.",2212.02195v2
+2022-12-08,Strong photon-magnon coupling using a lithographically defined organic ferrimagnet,"We demonstrate a hybrid quantum system composed of superconducting resonator
+photons and magnons hosted by the organic-based ferrimagnet vanadium
+tetracyanoethylene (V[TCNE]$_x$). Our work is motivated by the challenge of
+scalably integrating an arbitrarily-shaped, low-damping magnetic system with
+planar superconducting circuits, thus enabling a host of quantum magnonic
+circuit designs that were previously inaccessible. For example, by leveraging
+the inherent properties of magnons, one can enable nonreciprocal
+magnon-mediated quantum devices that use magnon propagation rather than
+electrical current. We take advantage of the properties of V[TCNE]$_x$, which
+has ultra-low intrinsic damping, can be grown at low processing temperatures on
+arbitrary substrates, and can be patterned via electron beam lithography. We
+demonstrate the scalable, lithographically integrated fabrication of hybrid
+quantum magnonic devices consisting of a thin-film superconducting resonator
+coupled to a low-damping, thin-film V[TCNE]$_x$ microstructure. Our devices
+operate in the strong coupling regime, with a cooperativity as high as 1181(44)
+at T$\sim$0.4 K, suitable for scalable quantum circuit integration. This work
+paves the way for the exploration of high-cooperativity hybrid magnonic quantum
+devices in which magnonic circuits can be designed and fabricated as easily as
+electrical wires.",2212.04423v1
+2023-01-23,Estimation of turbulent proton and electron heating rates via Landau damping constrained by Parker Solar Probe observations,"The heating of ions and electrons due to turbulent dissipation plays a
+crucial role in the thermodynamics of the solar wind and other plasma
+environments. Using magnetic field and thermal plasma observations from the
+first two perihelia of the Parker Solar Probe (PSP), we model the relative
+heating rates as a function of radial distance, magnetic spectra, and plasma
+conditions, enabling us to better characterize the thermodynamics of the inner
+heliosphere. We employ the Howes et al. 2008 steady-state cascade model, which
+considers the behavior of turbulent, low-frequency, wavevector-anisotropic,
+critically balanced Alfv\'enic fluctuations that dissipate via Landau damping
+to determine proton-to-electron heating rates $Q_p/Q_e$. We distinguish
+ion-cyclotron frequency circularly polarized waves from low-frequency
+turbulence and constrain the cascade model using spectra constructed from the
+latter. We find that the model accurately describes the observed energy
+spectrum from over 39.4 percent of the intervals from Encounters 1 and 2,
+indicating the possibility for Landau damping to heat the young solar wind. The
+ability of the model to describe the observed turbulent spectra increases with
+the ratio of thermal-to-magnetic pressure, $\beta_p$, indicating that the model
+contains the necessary physics at higher $\beta_p$. We estimate high magnitudes
+for the Kolmogorov constant which is inversely proportional to the non-linear
+energy cascade rate. We verify the expected strong dependency of $Q_p/Q_e$ on
+$\beta_p$ and the consistency of the critical balance assumption.",2301.09713v1
+2023-02-02,Leveraging symmetry for an accurate spin-orbit torques characterization in ferrimagnetic insulators,"Spin-orbit torques (SOTs) have emerged as an efficient means to electrically
+control the magnetization in ferromagnetic heterostructures. Lately, an
+increasing attention has been devoted to SOTs in heavy metal (HM)/magnetic
+insulator (MI) bilayers owing to their tunable magnetic properties and
+insulating nature. Quantitative characterization of SOTs in HM/MI
+heterostructures are, thus, vital for fundamental understanding of charge-spin
+interrelations and designing novel devices. However, the accurate determination
+of SOTs in MIs have been limited so far due to small electrical signal outputs
+and dominant spurious thermoelectric effects caused by Joule heating. Here, we
+report a simple methodology based on harmonic Hall voltage detection and
+macrospin simulations to accurately quantify the damping-like and field-like
+SOTs, and thermoelectric contributions separately in MI-based systems.
+Experiments on the archetypical Bi-doped YIG/Pt heterostructure using the
+developed method yield precise values for the field-like and damping-like SOTs,
+reaching -0.14 and -0.15 mT per 1.7x$10^{ 11}$ A/$m^2$, respectively. We
+further reveal that current-induced Joule heating changes the spin transparency
+at the interface, reducing the spin Hall magnetoresistance and damping-like
+SOT, simultaneously. These results and the devised method can be beneficial for
+fundamental understanding of SOTs in MI-based heterostructures and designing
+new devices where accurate knowledge of SOTs is necessary.",2302.01141v2
+2022-12-31,Genuine three qubit Einstein-Podolsky-Rosen steering under decoherence: Revealing hidden genuine steerability via pre-processing,"The behaviour of genuine EPR steering of three qubit states under various
+environmental noises is investigated. In particular, we consider the two
+possible steering scenarios in the tripartite setting: (1 -> 2), where Alice
+demonstrates genuine steering to Bob-Charlie, and (2 -> 1), where Alice-Bob
+together demonstrates genuine steering to Charlie. In both these scenarios, we
+analyze the genuine steerability of the generalized Greenberger-Horne-Zeilinger
+(gGHZ) states or the W-class states under the action of noise modeled by
+amplitude damping (AD), phase flip (PF), bit flip (BF), and phase damping (PD)
+channels. In each case, we consider three different interactions with the noise
+depending upon the number of parties undergoing decoherence. We observed that
+the tendency to demonstrate genuine steering decreases as the number of parties
+undergoing decoherence increases from one to three. We have observed several
+instances where the genuine steerability of the state revives after collapsing
+if one keeps on increasing the damping. However, the hidden genuine
+steerability of a state cannot be revealed solely from the action of noise. So,
+the parties having a characterized subsystem, perform local pre-processing
+operations depending upon the steering scenario and the state shared with the
+dual intent of revealing hidden genuine steerability or enhancing it.",2302.02987v1
+2023-02-20,Optimal energy harvesting efficiency from vortex-induced vibration of a circular cylinder under flow,"This work applies a combined approach a reduced-order model (ROM) together
+with experiments and direct numerical simulations to investigate the optimal
+efficiency of fluid-flow energy harvesting from transverse vortex-induced
+vibration (VIV) of a circular cylinder. High resolution efficiency maps were
+predicted over wide ranges of flow reduced velocities and structural damping
+ratios, and the maximum efficiency and optimal settings of damping ratio and
+reduced velocity were then examined for different mass ratios and Reynolds
+numbers. Efficiencies predicted by the ROM were also validated against either
+experiments or direct simulations. The present work indicates that: (i) the
+maximum efficiency is controlled by both the incoming reduced velocity and the
+product of mass ratio and structural damping ratio, which is similar to the
+maximum amplitude of VIV; (ii) the maximum efficiency at a relatively high
+Reynolds number ($Re \approx 6 \times 10^3$) in subcritical regime is higher
+than that of a low Reynolds number ($Re = 150$) in laminar regime; (iii) the
+energy harvesting efficiency from VIV of a circular cylinder with a low mass
+ratio is more robust than that with a high mass ratio. This finding suggests
+that the VIV harvester performs better in water than in air.",2302.09975v1
+2023-04-12,Liouvillian exceptional points in continuous variable system,"The Liouvillian exceptional points for a quantum Markovian master equation of
+an oscillator in a generic environment are obtained. They occur at the points
+when the modified frequency of the oscillator vanishes, whereby the eigenvalues
+of the Liouvillian become real. In a generic system there are two parameters
+that modify the oscillator's natural frequency. One of the parameters can be
+the damping rate. The exceptional point then corresponds to critical damping of
+the oscillator. This situation is illustrated by the Caldeira--Leggett (CL)
+equation and the Markovian limit of the Hu--Paz--Zhang (HPZ) equation. The
+other parameter changes the oscillator's effective mass whereby the exceptional
+point is reached in the limit of extremely heavy oscillator. This situation is
+illustrated by a modified form of the Kossakowski--Lindblad (KL) equation. The
+eigenfunctions coalesce at the exceptional points and break into subspaces
+labelled by a natural number $N$. In each of the $N$-subspace, there is a
+$(N+1)$-fold degeneracy and the Liouvillian has a Jordan block structure of
+order-$(N+1)$. We obtain the explicit form of the generalized eigenvectors for
+a few Liouvillians. Because of the degeneracies, there is a freedom of choice
+in the generalized eigenfunctions. This freedom manifests itself as an
+invariance in the Jordan block structure under a similarity transformation
+whose form is obtained. We compare the relaxation of the first excited state of
+an oscillator in the underdamped region, critically damped region which
+corresponds to the exceptional point, and overdamped region using the
+generalized eigenvectors of the CL equation.",2304.05792v2
+2023-04-13,Network-Reconfiguration-Aware Power Oscillation Damping Controller for Newly Commissioned Converter-Interfaced Power Plants,"In recent years, transmission system operators have started requesting
+converter-interfaced generators (CIGs) to participate in grid services such as
+power oscillation damping (POD). As power systems are prone to topology changes
+because of connection and disconnection of generators and electrical lines, one
+of the most important requirements in the POD controller design is to account
+for these changes and to deal with them by using either adaptive or robust
+approaches. The robust approach is usually preferred by system operators
+because of the fixed structure of the controller. In this paper, a procedure to
+design POD controllers for CIG-based power plants that takes into consideration
+all possible network configurations is presented. This procedure is based on
+frequency-response techniques, so it is suitable for the commissioning in newly
+installed power plants, even in those cases when a detailed small-signal model
+of the system is not available. This procedure can be used to damp critical
+system modes by using active power, reactive power, or both power components
+simultaneously. The proposed procedure is applied to the design of the POD
+controller for a CIG-based power plant connected to the IEEE 39 Bus system.
+Simulations performed in Matlab and SimPowerSystems are used to validate the
+proposed design procedure.",2304.06555v1
+2023-06-13,Particle-resolved study of the onset of turbulence,"The transition from laminar to turbulent flow is an immensely important topic
+that is still being studied. Here we show that complex plasmas, i.e.,
+microparticles immersed in a low temperature plasma, make it possible to study
+the particle-resolved onset of turbulence under the influence of damping, a
+feat not possible with conventional systems. We performed three-dimensional
+(3D) molecular dynamics (MD) simulations of complex plasmas flowing past an
+obstacle and observed 3D turbulence in the wake and fore-wake region of this
+obstacle. We found that we could reliably trigger the onset of turbulence by
+changing key parameters such as the flow speed and particle charge, which can
+be controlled in experiments, and show that the transition to turbulence
+follows the conventional pathway involving the intermittent emergence of
+turbulent puffs. The power spectra for fully developed turbulence in our
+simulations followed the -5/3 power law of Kolmogorovian turbulence in both
+time and space. We demonstrate that turbulence in simulations with damping
+occurs after the formation of shock fronts, such as bow shocks and Mach cones.
+By reducing the strength of damping in the simulations, we could trigger a
+transition to turbulence in an undamped system. This work opens the pathway to
+detailed experimental and simulation studies of the onset of turbulence on the
+level of the carriers of the turbulent interactions, i.e., the microparticles.",2306.07711v1
+2023-07-10,Vibroacoustic simulations of acoustic damping materials using a fictitious domain approach,"The numerical investigation of acoustic damping materials, such as foams,
+constitutes a valuable enhancement to experimental testing. Typically, such
+materials are modeled in a homogenized way in order to reduce the computational
+effort and to circumvent the need for a computational mesh that resolves the
+complex micro-structure. However, to gain detailed insight into the acoustic
+behavior, e.g., the transmittance of noise, such fully resolved models are
+mandatory. The meshing process can still be avoided by using a ficticious
+domain approach. We propose the finite cell method, which combines the
+ficticious domain approach with high-order finite elements and resolves the
+complex geometry using special quadrature rules. In order to take into account
+the fluid-filled pores of a typical damping material, a coupled vibroacoustic
+problem needs to be solved. To this end, we construct two separate finite cell
+discretizations and prescribe coupling conditions at the interface in the usual
+manner. The only difference to a classical boundary fitted approach to
+vibroacoustics is that the fluid-solid interface is immersed into the
+respective discretization and does not correspond to the element boundaries.
+The proposed enhancement of the finite cell method for vibroacoustics is
+verified based on a comparison with commercial software and used within an
+exemplary application.",2307.04624v1
+2023-07-12,A coupled rate-dependent/rate-independent system for adhesive contact in Kirchhoff-Love plates,"We perform a dimension reduction analysis for a coupled
+rate-dependent/rate-independent adhesive-contact model in the setting of
+visco-elastodynamic plates. We work with a weak solvability notion inspired by
+the theory of (purely) rate-independent processes, and accordingly term the
+related solutions `Semistable Energetic'. For Semistable Energetic solutions,
+the momentum balance holds in a variational sense, whereas the flow rule for
+the adhesion parameter is replaced by a semi-stability condition coupled with
+an energy-dissipation inequality. Prior to addressing the dimension reduction
+analysis, we show that Semistable Energetic solutions to the three-dimensional
+damped adhesive contact model converge, as the viscosity term tends to zero, to
+three-dimensional Semistable Energetic solutions for the undamped corresponding
+system. We then perform a dimension reduction analysis, both in the case of a
+vanishing viscosity tensor (leading, in the limit, to an undamped model), and
+in the complementary setting in which the damping is assumed to go to infinity
+as the thickness of the plate tends to zero. In both regimes, the presence of
+adhesive contact yields a nontrivial coupling of the in-plane and out-of-plane
+contributions. In the undamped scenario we obtain in the limit an
+energy-dissipation inequality and a semistability condition. In the damped
+case, instead, we achieve convergence to an enhanced notion of solution,
+fulfilling an energy-dissipation balance.",2307.06327v1
+2023-08-28,The Effects of Non-Equilibrium Velocity Distributions on Alfvén Ion-Cyclotron Waves in the Solar Wind,"In this work, we investigate how the complex structure found in solar wind
+proton velocity distribution functions (VDFs), rather than the commonly assumed
+two-component bi-Maxwellian structure, affects the onset and evolution of
+parallel-propagating microinstabilities. We use the Arbitrary Linear Plasma
+Solver (ALPS), a numerical dispersion solver, to find the real frequencies and
+growth/damping rates of the Alfv\'en modes calculated for proton VDFs extracted
+from Wind spacecraft observations of the solar wind. We compare this wave
+behavior to that obtained by applying the same procedure to core-and-beam
+bi-Maxwellian fits of the Wind proton VDFs. We find several significant
+differences in the plasma waves obtained for the extracted data and
+bi-Maxwellian fits, including a strong dependence of the growth/damping rate on
+the shape of the VDF. By application of the quasilinear diffusion operator to
+these VDFs, we pinpoint resonantly interacting regions in velocity space where
+differences in VDF structure significantly affect the wave growth and damping
+rates. This demonstration of the sensitive dependence of Alfv\'en mode behavior
+on VDF structure may explain why the Alfv\'en ion-cyclotron instability
+thresholds predicted by linear theory for bi-Maxwellian models of solar wind
+proton background VDFs do not entirely constrain spacecraft observations of
+solar wind proton VDFs, such as those made by the Wind spacecraft.",2308.14944v1
+2023-08-31,Search for the gamma-ray spectral lines with the DAMPE and the Fermi-LAT observations,"Weakly interacting massive particles, as a major candidate of dark matter
+(DM), may directly annihilate or decay into high-energy photons, producing
+monochromatic spectral lines in the gamma-ray band. These spectral lines, if
+detected, are smoking-gun signatures for the existence of new physics. Using
+the 5 years of DAMPE and 13 years of Fermi-LAT data, we search for line-like
+signals in the energy range of 3 GeV to 1 TeV from the Galactic halo. Different
+regions of interest are considered to accommodate different DM density
+profiles. We do not find any significant line structure, and the previously
+reported line-like feature at $\sim$133 GeV is also not detected in our
+analysis. Adopting a local DM density of $\rho_{\rm local}=0.4\,{\rm
+GeV\,cm^{-3}}$, we derive 95% confidence level constraints on the
+velocity-averaged cross-section of $\langle{\sigma v}\rangle_{\gamma\gamma}
+\lesssim 4 \times 10^{-28}\,{\rm cm^{3}\,s^{-1}}$ and the decay lifetime of
+$\tau_{\gamma\nu} \gtrsim 5 \times 10^{29}\,{\rm s}$ at 100 GeV, achieving the
+strongest constraints to date for the line energies of 6-660 GeV. The
+improvement stems from the longer Fermi-LAT data set used and the inclusion of
+DAMPE data in the analysis. The simultaneous use of two independent data sets
+could also reduce the systematic uncertainty of the search.",2308.16762v1
+2023-09-06,Strong magnon-magnon coupling in an ultralow damping all-magnetic-insulator heterostructure,"Magnetic insulators such as yttrium iron garnets (YIGs) are of paramount
+importance for spin-wave or magnonic devices as their ultralow damping enables
+ultralow power dissipation that is free of Joule heating, exotic magnon quantum
+state, and coherent coupling to other wave excitations. Magnetic insulator
+heterostructures bestow superior structural and magnetic properties and house
+immense design space thanks to the strong and engineerable exchange interaction
+between individual layers. To fully unleash their potential, realizing low
+damping and strong exchange coupling simultaneously is critical, which often
+requires high quality interface. Here, we show that such a demand is realized
+in an all-insulator thulium iron garnet (TmIG)/YIG bilayer system. The ultralow
+dissipation rates in both YIG and TmIG, along with their significant spin-spin
+interaction at the interface, enable strong and coherent magnon-magnon coupling
+with a benchmarking cooperativity value larger than the conventional
+ferromagnetic metal-based heterostructures. The coupling strength can be tuned
+by varying the magnetic insulator layer thickness and magnon modes, which is
+consistent with analytical calculations and micromagnetic simulations. Our
+results demonstrate TmIG/YIG as a novel platform for investigating hybrid
+magnonic phenomena and open opportunities in magnon devices comprising
+all-insulator heterostructures.",2309.03116v1
+2023-09-14,A new break near 10 TeV in the energy spectrum of protons according to data from space-based instruments: astrophysical interpretation,"Recent experimental data from space-based instruments of the DAMPE and CALET
+collaborations have shown that the energy spectrum of protons has a new
+feature, a break in the $\sim 10$ TeV region. In this energy range, the
+spectrum index of the observed particles varies from $-2.6$ to $-2.9$.
+  The purpose of this work is to establish the local sources's position and age
+that determine this break, the index of the proton generation spectrum in them,
+as well as the astrophysical interpretation of the results obtained in the
+DAMPE and CALET experiments.
+  Within the framework of the model of nonclassical diffusion of cosmic rays
+developed by the authors, which has break due to the propagation of particles
+in a sharply inhomogeneous (fractal type) galactic medium, it is shown that
+break in this energy range is formed by tevatron located at a distance of $\sim
+120$ pc from the Earth. These source, whose age is $\sim 5 \cdot 10^5$ years,
+generate particles with a spectrum index $\sim 2.7$.
+  The power-law behavior of the proton spectrum before and after the break,
+soft spectrum of particles generation in the source, first obtained in the
+DAMPE and CALET experiments, should be considered as an indication of the need
+to revise the standard paradigm accepted today about the sources of cosmic
+rays, mechanisms of particle acceleration in them and particles propagation in
+the Galaxy.",2309.07420v1
+2023-11-06,Phase mixing of propagating Alfv{é}n waves in a single-fluid partially ionized solar plasma,"Phase mixing of Alfven waves is one of the most promising mechanisms for
+heating of the solar atmosphere. The damping of waves in this case requires
+small transversal scales, relative to the magnetic field direction. Here this
+requirement is achieved by considering a transversal inhomogeneity in the
+equilibrium plasma density profile. Using a single fluid approximation of a
+partially ionized chromospheric plasma we study the effectiveness of the
+damping of phase mixed shear Alfven waves and investigate the effect of varying
+the ionization degree on the dissipation of waves. Our results show that the
+dissipation length of shear Alfven waves strongly depends on the ionization
+degree of the plasma, but more importantly, in a partially ionized plasma, the
+damping length of shear Alfven waves is several orders of magnitude shorter
+than in the case of a fully ionized plasma, providing evidence that phase
+mixing could be a large contributor to heating the solar chromosphere. The
+effectiveness of phase mixing is investigated for various ionization degrees,
+ranging from very weakly to very strongly ionized plasmas. Our results show
+that phase mixed propagating Alfven waves in a partially ionized plasma with
+ionization degrees in the range 0.518 to 0.657, corresponding to heights of
+1916 to 2150 km above the solar surface, can provide sufficient heating to
+balance chromospheric radiative losses in the quiet Sun.",2311.02989v1
+2023-11-15,Damped Proximal Augmented Lagrangian Method for weakly-Convex Problems with Convex Constraints,"We give a damped proximal augmented Lagrangian method (DPALM) for solving
+problems with a weakly-convex objective and convex linear/nonlinear
+constraints. Instead of taking a full stepsize, DPALM adopts a damped dual
+stepsize to ensure the boundedness of dual iterates. We show that DPALM can
+produce a (near) $\vareps$-KKT point within $O(\vareps^{-2})$ outer iterations
+if each DPALM subproblem is solved to a proper accuracy. In addition, we
+establish overall iteration complexity of DPALM when the objective is either a
+regularized smooth function or in a regularized compositional form. For the
+former case, DPALM achieves the complexity of
+$\widetilde{\mathcal{O}}\left(\varepsilon^{-2.5} \right)$ to produce an
+$\varepsilon$-KKT point by applying an accelerated proximal gradient (APG)
+method to each DPALM subproblem. For the latter case, the complexity of DPALM
+is $\widetilde{\mathcal{O}}\left(\varepsilon^{-3} \right)$ to produce a near
+$\varepsilon$-KKT point by using an APG to solve a Moreau-envelope smoothed
+version of each subproblem. Our outer iteration complexity and the overall
+complexity either generalize existing best ones from unconstrained or
+linear-constrained problems to convex-constrained ones, or improve over the
+best-known results on solving the same-structured problems. Furthermore,
+numerical experiments on linearly/quadratically constrained non-convex
+quadratic programs and linear-constrained robust nonlinear least squares are
+conducted to demonstrate the empirical efficiency of the proposed DPALM over
+several state-of-the art methods.",2311.09065v1
+2023-12-07,Nonlinear aspects of stochastic particle acceleration,"In turbulent magnetized plasmas, charged particles can be accelerated to high
+energies through their interactions with the turbulent motions. As they do so,
+they draw energy from the turbulence, possibly up to the point where they start
+modifying the turbulent cascade. Stochastic acceleration then enters a
+nonlinear regime because turbulence damping back-reacts in turn on the
+acceleration process. This article develops a phenomenological model to examine
+this situation in detail and to explore its consequences for the particle and
+turbulent energy spectra. We determine a criterion that specifies the threshold
+of nonthermal particle energy density and the characteristic momentum beyond
+which back-reaction becomes effective. Once the back-reaction sets in, the
+turbulence cascade becomes damped below a length scale that keeps increasing in
+time. The accelerated particle momentum distribution develops a near power-law
+of the form ${\rm d}n/{\rm d}p\propto p^{-s}$ with $s\sim2$ beyond the momentum
+at which back-reaction first sets in. At very high energies, where the
+gyroradius of accelerated particles becomes comparable to the outer scale of
+the turbulence, the energy spectrum can display an even harder spectrum with
+$s\sim 1.3-1.5$ over a short segment. The low-energy part of the spectrum,
+below the critical momentum, is expected to be hard ($s\sim 1$ or harder), and
+shaped by any residual acceleration process in the damped region of the
+turbulence cascade. This characteristic broken power-law shape with $s\sim 2$
+at high energies may find phenomenological applications in various high-energy
+astrophysical contexts.",2312.04443v2
+2023-12-12,Circularization in the damped Kepler problem,"In this paper, we revisit the damped Kepler problem within a general family
+of nonlinear damping forces with magnitude $\delta \vert u\vert^{\beta}\vert
+\dot u\vert^{\alpha+1}$, depending on three parameters $\delta>0,\alpha\ge 0$
+and $\beta\ge 0$, and address the general question of circularization whereby
+orbits tend to become more circular as they approach the sun. Our approach is
+based on dynamical systems theory, using blowup and desingularization as our
+main technical tools. We find that $\gamma=\alpha+2\beta-3$ is an important
+quantity, with the special case $\gamma=0$ separating circularization
+($-3<\gamma<0$) where the eccentricity converges to zero, i.e. $e(t)\rightarrow
+0$ as $u(t)\rightarrow 0$, from cases ($\gamma>0$) where $e(t)\rightarrow 1$ as
+$u(t)\rightarrow 0$, both on open sets of initial conditions. We find that
+circularization for $-3<\gamma<0$ occurs due to asymptotic stability of a
+zero-Hopf equilibrium point (i.e., the eigenvalues are $\pm i \omega,0$) of a
+three-dimensional reduced problem (which is analytic in the blowup
+coordinates). The attraction is therefore not hyperbolic and in particular not
+covered by standard dynamical systems theory. Instead we use recent results on
+normal forms of the zero-Hopf to locally bring the system into a form where the
+stability can be addressed directly. We believe that our approach can be used
+to describe unbounded solutions.",2312.07249v1
+2023-12-21,Annealing reduces Si$_3$N$_4$ microwave-frequency dielectric loss in superconducting resonators,"The dielectric loss of silicon nitride (Si$_3$N$_4$) limits the performance
+of microwave-frequency devices that rely on this material for sensing, signal
+processing, and quantum communication. Using superconducting resonant circuits,
+we measure the cryogenic loss tangent of either as-deposited or
+high-temperature annealed stoichiometric Si$_3$N$_4$ as a function of drive
+strength and temperature. The internal loss behavior of the electrical
+resonators is largely consistent with the standard tunneling model of two-level
+systems (TLS), including damping caused by resonant energy exchange with TLS
+and by the relaxation of non-resonant TLS. We further supplement the TLS model
+with a self-heating effect to explain an increase in the loss observed in
+as-deposited films at large drive powers. Critically, we demonstrate that
+annealing remedies this anomalous power-induced loss, reduces the
+relaxation-type damping by more than two orders of magnitude, and reduces the
+resonant-type damping by a factor of three. Employing infrared absorption
+spectroscopy, we find that annealing reduces the concentration of hydrogen in
+the Si$_3$N$_4$, suggesting that hydrogen impurities cause substantial
+dissipation.",2312.13504v1
+2024-01-11,Instability windows of relativistic r-modes,"The detectability of the gravitational-wave signal from $r$-modes depends on
+the interplay between the amplification of the mode by the CFS instability and
+its damping due to dissipative mechanisms present in the stellar matter. The
+instability window of $r$-modes describes the region of stellar parameters
+(angular velocity, $\Omega$, and redshifted stellar temperature, $T^\infty$),
+for which the mode is unstable. In this study, we reexamine this problem in
+nonbarotropic neutron stars, taking into account the previously overlooked
+nonanalytic behavior (in $\Omega$) of relativistic $r$-modes and enhanced
+energy dissipation resulting from diffusion in superconducting stellar matter.
+We demonstrate that at slow rotation rates, relativistic $r$-modes exhibit
+weaker amplification by the CFS instability compared to Newtonian ones.
+However, their dissipation through viscosity and diffusion is significantly
+more efficient. In rapidly rotating neutron stars within the framework of
+general relativity, the amplification of $r$-modes by the CFS mechanism and
+their damping due to shear viscosity become comparable to those predicted by
+Newtonian theory. In contrast, the relativistic damping of the mode by
+diffusion and bulk viscosity remains significantly stronger than in the
+nonrelativistic case. Consequently, account for diffusion and general
+relativity leads to a substantial modification of the $r$-mode instability
+window compared to the Newtonian prediction. This finding is important for the
+interpretation of observations of rotating neutron stars, as well as for
+overall understanding of $r$-mode physics.",2401.06200v1
+2024-02-02,Controllable frequency tunability and parabolic-like threshold current behavior in spin Hall nano-oscillators,"We investigate the individual impacts of critical magnetodynamical
+parameters-effective magnetization and magnetic damping-on the auto-oscillation
+characteristics of nano-constriction-based Spin Hall Nano-Oscillators (SHNOs).
+Our micromagnetic simulations unveil a distinctive non-monotonic relationship
+between current and auto-oscillation frequency in out-of-plane magnetic fields.
+The influence of effective magnetization on frequency tunability varies with
+out-of-plane field strengths. At large out-of-plane fields, the frequency
+tunability is predominantly governed by effective magnetization, achieving a
+current tunability of 1 GHz/mA-four times larger than that observed at the
+lowest effective magnetization. Conversely, at low out-of-plane fields,
+although a remarkably high-frequency tunability of 4 GHz/mA is observed, the
+effective magnetization alters the onset of the transition from a linear-like
+mode to a spin-wave bullet mode. Magnetic damping primarily affects the
+threshold current with negligible impact on auto-oscillation frequency
+tunability. The threshold current scales linearly with increased magnetic
+damping at a constant out-of-plane field but exhibits a parabolic behavior with
+variations in out-of-plane fields. This behavior is attributed to the
+qualitatively distinct evolution of the auto-oscillation mode across different
+out-of-plane field values. Our study not only extends the versatility of SHNOs
+for oscillator-based neuromorphic computing with controllable frequency
+tunability but also unveils the intricate auto-oscillation dynamics in
+out-of-plane fields.",2402.01570v1
+2024-02-06,The fermion self-energy and damping rate in a hot magnetized plasma,"We derive a general expression for the fermion self-energy in a hot
+magnetized plasma by using the Landau-level representation. In the one-loop
+approximation, the Dirac structure of the self-energy is characterized by five
+different functions that depend on the Landau-level index $n$ and the
+longitudinal momentum $p_z$. We derive general expressions for all five
+functions and obtain closed-form expressions for their imaginary parts. The
+latter receive contributions from three types of on-shell processes, which are
+interpreted in terms of Landau-level transitions, accompanied by a single
+photon (gluon) emission or absorption. By making use of the imaginary parts of
+the self-energy functions, we also derive the Landau-level dependent fermion
+damping rates $\Gamma_{n}(p_z)$ and study them numerically in a wide range of
+model parameters. We also demonstrate that the two-spin degeneracy of the
+Landau levels is lifted by the one-loop self-energy corrections. While the spin
+splitting of the damping rates is small, it may be important for some spin and
+chiral effects. We argue that the general method and the numerical results for
+the rates can have interesting applications in heavy-ion physics, astrophysics,
+and cosmology, where strongly magnetized QED or QCD plasmas are ubiquitous.",2402.04307v2
+2024-03-18,Radiative loss and ion-neutral collisional effects in astrophysical plasmas,"In this paper we study the role of radiative cooling in a two-fluid model
+consisting of coupled neutrals and charged particles. We first analyze the
+linearized two-fluid equations where we include radiative losses in the energy
+equation for the charged particles. In a 1D geometry for parallel propagation
+and in the limiting cases of weak and strong coupling, it can be shown
+analytically that the instability conditions for the thermal mode and the sound
+waves, the isobaric and isentropic criteria, respectively, remain unchanged
+with respect to one-fluid radiative plasmas. For the parameters considered in
+this paper, representative for the solar corona, the radiative cooling produces
+growth of the thermal mode and damping of the sound waves. When neutrals are
+included and are sufficiently coupled to the charges, the thermal mode growth
+rate and the wave damping both reduce by the same factor, which depends on the
+ionization fraction only. For a heating function which is constant in time, we
+find that the growth of the thermal mode and the damping of the sound waves are
+slightly larger. The numerical calculation of the eigenvalues of the general
+system of equations in a 3D geometry confirm the analytic results. We then run
+2D fully nonlinear simulations which give consistent results: a higher
+ionization fraction or lower coupling will increase the growth rate. The
+magnetic field contribution is negligible in the linear phase.
+Ionization-recombination effects might play an important role because the
+radiative cooling produces a large range of temperatures in the system. In the
+numerical simulation, after the first condensation phase, when the minimum
+temperature is reached, the fraction of neutrals increases four orders of
+magnitude because of the recombination.",2403.11900v1
+2024-04-02,A new gap in the critical exponent for semi-linear structurally damped evolution equations,"Our aim in this paper is to discuss the critical exponent in semi-linear
+structurally damped wave and beam equations with additional dispersion term.
+The special model we have in mind is $$
+u_{tt}(t,x)+(-\Delta)^{\sigma}u(t,x)+(-\Delta)^{2\delta}u(t,x)+2(-\Delta)^{\delta}u_{t}(t,x)=\left|u(t,x)\right|
+^{p} $$ where the initial displacement $u(0,x)=u_{0}(x)$, the initial velocity
+$u_{t}(0,x)=u_{1}(x)$ and the parameters $ t\in [0,\infty)$, $x\in
+\mathbb{R}^{n}$, $\sigma\geq 1$, $\delta\in(0,\frac{\sigma}{2})$, $p>1$. The
+solution to the linear equation at low frequency region involves an interplay
+of diffusion and oscillation phenomena represented by a real-complex Fourier
+multiplier of the form $$m(t,\xi)=\frac{e^{-|\xi|^{2\delta}t\pm
+i|\xi|^{\sigma}t}}{2i|\xi|^{\sigma}}, \ \ \xi\in \mathbb{R}^{n}, \ \
+i=\sqrt{-1}.$$ The scaling argument shows that the diffusive part leads to
+faster decay rates compared to the oscillatory one. This interplay creates a
+new gap in the critical exponent between the blow up (in finite time) result
+when $1<p<1+\frac{4\delta}{n-2\delta}$ (sub-critical case) and the global (in
+time) existence result when $p>1+\frac{\sigma+2\delta}{n-\sigma}$
+(super-critical case). We leave an open to show if this gap will be closed at
+least in low or high space dimensions because, to the best of authors
+knowledge, the necessary Fourier multiplier that leads to the sub-critical case
+does not explicitly appear in $m(t,\xi)$.",2404.01544v1
+1999-07-23,Autoregressive model of 1/f noise,"An analytically solvable model is proposed exhibiting 1/f spectrum in any
+desirably wide range of frequency (but excluding the point f=0). The model
+consists of pulses whose recurrence times obey an autoregressive process with
+very small damping.",9907008v1
+1996-08-22,Evolution of Neutral Gas at High Redshift -- Implications for the Epoch of Galaxy Formation,"Though observationally rare, damped Lya absorption systems dominate the mass
+density of neutral gas in the Universe. Eleven high redshift damped Lya systems
+covering 2.8<z<4.4 were discovered in 26 QSOs from the APM z>4 QSO Survey,
+extending these absorption system surveys to the highest redshifts currently
+possible. Combining our new data set with previous surveys we find that the
+cosmological mass density in neutral gas, omega_g, does not rise as steeply
+prior to z~2 as indicated by previous studies. There is evidence in the
+observed omega_g for a flattening at z~2 and a possible turnover at z~3. When
+combined with the decline at z>3.5 in number density per unit redshift of
+damped systems with column densities log N(HI)>21 atoms cm^-2, these results
+point to an epoch at z>3 prior to which the highest column density damped
+systems are still forming. We find that over the redshift range 2<z<4 the total
+mass in neutral gas is marginally comparable with the total visible mass in
+stars in present day galaxies. However, if one considers the total mass visible
+in stellar disks alone, ie excluding galactic bulges, the two values are
+comparable. We are observing a mass of neutral gas comparable to the mass of
+visible disk stars. Lanzetta, Wolfe & Turnshek (1995) found that omega_g(z~3.5)
+was twice omega_g(z~2), implying a much larger amount of star formation must
+have taken place between z=3.5 and z=2 than is indicated by metallicity
+studies. This created a `cosmic G-dwarf problem'. The more gradual evolution of
+omega_g we find alleviates this. These results have profound implications for
+theories of galaxy formation.",9608147v1
+1997-07-14,Damped Lyman-alpha Absorption Associated with an Early-Type Galaxy at Redshift z = 0.16377,"We report new HST and ground-based observations of a damped Lyman-alpha
+absorption system toward the QSO 0850+4400. The redshift of the absorption
+system is z = 0.163770 and the neutral hydrogen column density of the
+absorption system is log N = 19.81 cm**-2. The absorption system is by far the
+lowest redshift confirmed damped Lyman-alpha absorption system yet identified,
+which provides an unprecedented opportunity to examine the nature, impact
+geometry, and kinematics of the absorbing galaxy in great detail. The
+observations indicate that the absorption system is remarkable in three
+respects: First, the absorption system is characterized by weak metal
+absorption lines and a low metal abundance, possibly less than 4% of the solar
+metal abundance. This cannot be explained as a consequence of dust, because the
+neutral hydrogen column density of the absorption system is far too low for
+obscuration by dust to introduce any significant selection effects. Second, the
+absorption system is associated with a moderate-luminosity early-type S0
+galaxy, although the absorption may actually arise in one of several very faint
+galaxies detected very close to the QSO line of sight. Third, the absorbing
+material moves counter to the rotating galaxy disk, which rules out the
+possibility that the absorption arises in a thin or thick co-rotating gaseous
+disk. These results run contrary to the expectation that low-redshift damped
+Lyman-alpha absorption systems generally arise in the gas- and metal-rich inner
+parts of late-type spiral galaxies. We suggest instead that mounting evidence
+indicates that low-redshift galaxies of a variety of morphological types may
+contain significant quantities of low metal abundance gas at large
+galactocentric distances.",9707157v1
+1997-08-27,Reionization of the Intergalactic Medium and the Damping Wing of the Gunn-Peterson Trough,"Observations of high-redshift quasars show that the IGM must have been
+reionized at some redshift $z>5$. If a source of radiation could be observed at
+the rest-frame Lya wavelength, at a sufficiently high redshift where some of
+the IGM in the line-of-sight was not yet reionized, the Gunn-Peterson trough
+should be present. Longward of the Lya wavelength, a damping wing should be
+observed caused by the neutral IGM whose absorption profile can be predicted.
+Measuring the shape of this damping wing would provide irrefutable evidence of
+the observation of the IGM before reionization, and a determination of the
+density of the neutral IGM. This measurement might be hindered by the possible
+presence of a dense absorption system associated with the source.
+  Shortward of the \lya wavelength, absorption should be seen from the patchy
+structure of the IGM in the process of reionization. We show that a complete
+Gunn-Peterson trough is most likely to continue to be observed through the
+epoch where the IGM is partially ionized. The damping wings of the neutral
+patches should overlap if the proper pathlength through an ionized region is
+less than 1 h^{-1} Mpc; even in larger ionized regions, the characteristic
+background intensity should be low enough to yield a very high optical depth
+due to the residual neutral fraction, although occasionally some flux may be
+transmitted through large, underdense voids within an ionized region. The case
+of the HeII reionization is also discussed, and we argue that helium was
+already doubly ionized by z=3 throughout the IGM.
+  The recently discovered afterglows of gamma-ray bursts might soon be observed
+at very high redshifts. Their featureless continuum spectrum and high
+luminosities make them ideal sources for studying absorption by the IGM.",9708253v1
+1997-09-16,On the nature of z(abs) ~ z(em) damped absorbers in quasar spectra,"We present spectroscopic observations of the damped Ly-alpha absorber at
+redshift z=1.9342 seen in the spectrum of the quasar Q0151+048A. The redshift
+of the absorber is greater than the redshift of the quasar, so the system
+resembles the z(abs) ~ z(em) damped absorber at z=2.81 towards the quasar
+PKS0528-250. We have previously reported the detection of Ly-alpha emission
+from the latter absorber, one of only two damped absorbers for which Ly-alpha
+emission has unambiguously been detected. The resemblance between the
+PKS0528-250 and Q0151+048A systems is made closer by the detection of a weak
+emission feature in the trough of the Q0151+048A absorber. This leads us to
+consider whether these z(abs) ~ z(em) DLA absorbers are different objects to
+the intervening DLA absorbers. Two possibilities are examined and rejected.
+Firstly the Q0151+048A and PKS0528-250 z(abs) ~ z(em) absorbers appear to be
+unrelated to the intrinsic absorbers (i.e. gas close to the quasar nucleus,
+ejected by the quasar), as intrinsic absorbers are of higher metallicity, have
+higher ionisation parameter, and show complex absorption profiles. Secondly
+these two DLA absorbers cannot be equated with the gaseous disks of the quasar
+host galaxies, as the absorber redshifts differ significantly from the quasar
+systemic redshifts. It is likely, then, that intrinsically the z(abs) ~ z(em)
+DLA absorbers are the same as the intervening DLA absorbers, so that
+peculiarities in some of the z(abs) ~ z(em) absorbers can be ascribed to their
+different environment i.e. proximity to the quasar, or membership of the same
+cluster as the quasar. We point out that the proximity effect may play some
+role, by reducing the Ly-alpha forest line blanketing of any Ly-alpha emission
+line from z(abs) ~ z(em) absorbers.",9709160v1
+1998-01-15,A HST Spectroscopic study of QSOs with intermediate redshift damped Lyman-alpha systems,"We present HST spectra for a sample of six QSOs with intermediate redshift
+(z_a < 1) damped Ly-alpha systems. These observations aim at measuring the HI
+column density and detect metal lines in order to investigate the metal
+enrichment of the gas, as well as the presence of neutral species, molecules
+and dust. All systems selected on the basis of 21 cm absorption and/or strong
+FeII lines relative to MgII ones turn out to have N(HI) larger than 10^20 cm-2.
+It appears that although the scatter of metallicities is as large at z_a<1 as
+at high redshift, an increasing proportion of systems with metallicities ~ 30%
+solar are found when going at lower redshifts. Our results suggest that
+available observations may be biased against dust-rich absorbers. Further, when
+all available measurements of N(HI) and [Zn/H] are considered, a clear
+deficiency of systems with large N(HI) and high metallicity is apparent. We
+conclude that dust extinction causes a preferential selection of QSOs with
+intervening gas relatively poor in metals, dust and molecules. As a
+consequence, the high end of the HI column density distribution (and hence
+Omega_g, the contribution of neutral gas to the cosmological mass density) is
+probably more heavily underestimated than previously thought, especially at low
+redshift. Such a bias could also explain the high incidence of non-spiral
+morphologies in our sample. We stress that observation of a larger sample of
+low z damped Ly-alpha systems as well as surveys of damped Ly-alpha systems in
+fainter QSOs would give a more representative view of the true diversity of
+absorber properties and should help to probe the denser phases of the
+interstellar medium in distant galaxies.",9801146v1
+1998-06-15,On the kinematics of damped Lyman-alpha systems,"We report on high spectral resolution observations of five damped Ly-alpha
+absorbers. Line velocity profiles and heavy element abundances are discussed.
+Nitrogen is found to have abundances less than silicon in the systems toward Q
+0347-383, Q 0913+072, and Q 1213+093. The absorber toward Q 0913+072 is the
+most metal-deficient damped system known, with [Fe/H] < -3.2. The simple
+kinematical structure of the metal absorptions makes this system ideal to
+discuss the [O/Si] and [N/O] ratios. We find [O/H] ~ -2.7 and -2.7 < [Si/H] <
+-2.2. By combining these data with information gathered in the literature, we
+study the kinematics of the low and high ionization phases in a sample of 26
+damped Ly-alpha systems in the redshift range 1.17-4.38. We note a strong
+correlation between the velocity broadenings of the SiII,1808 and FeII,1608
+lines whatever the line optical depth, implying that the physical conditions
+are quite homogeneous in the sample. Statistically this shows that large
+variations of abundance ratios and thus large variations of depletion into dust
+grains are unlikely. The velocity broadening of the absorption lines, Delta V,
+is correlated with the asymmetry of the lines for Delta V < 150 km/s. The
+broader the line the more asymmetric it is, as expected in case rotation
+dominates the line broadening. However this correlation does not hold for
+larger Delta V suggesting that evidence for rotational motions is restricted to
+velocity broadenings Delta V < 150 km/s. The systems with Delta V > 200 km/s
+are peculiar with kinematics consistent with random motions. They show
+sub-systems as those expected if the objects are in the process of merging
+(abridged).",9806202v1
+1999-10-07,Si and Mn Abundances in Damped Lya Systems with Low Dust Content,"We have measured the abundances of Zn, Si, Mn, Cr, Fe, and Ni in three damped
+Lyman alpha systems at redshifts z < 1 from high resolution echelle spectra of
+QSOs recorded with the Keck I telescope. In all three cases the abundances of
+Cr, Fe, and Ni relative to Zn indicate low levels of dust depletions. We
+propose that when the proportion of refractory elements locked up in dust
+grains is less than about 50 percent, it is plausible to assume an
+approximately uniform level of depletion for all grain constituents and, by
+applying a small dust correction, recover the intrisic abundances of Si and Mn.
+We use this approach on a small sample of damped systems for which it is
+appropriate, with the aim of comparing the metallicity dependence of the ratios
+[Si/Fe] and [Mn/Fe] with analogous measurements in Milky Way stars. The main
+conclusion is that the relative abundances of both elements in distant galaxies
+are broadly in line with expectations based on Galactic data. Si displays a
+mild enhancement at low metallicities, as expected for an alpha-capture
+element, but there are also examples of near-solar [Si/Fe] at [Fe/H] < -1. The
+underabundance of Mn at low metallicities is possibly even more pronounced than
+that in metal-poor stars, and no absorption system has yet been found where
+[Mn/Fe] is solar. The heterogeneous chemical properties of damped Lyman alpha
+systems, evident even from this limited set of measurements, provide further
+support for the conclusion from imaging studies that a varied population of
+galaxies gives rise to this class of QSO absorbers.",9910131v1
+1999-11-23,On the orbital evolution and growth of protoplanets embedded in a gaseous disc,"We present a new computation of the linear tidal interaction of a
+protoplanetary core with a thin gaseous disc in which it is fully embedded. For
+the first time a discussion of the orbital evolution of cores with eccentricity
+(e) significantly larger than the gas-disc scale height to radius ratio (H/r)
+is given. We find that the direction of orbital migration reverses for
+e>1.1H/r. This occurs as a result of the orbital crossing of resonances in the
+disc that do not overlap the orbit when the eccentricity is very small. Simple
+expressions giving approximate fits to the eccentricity damping rate and the
+orbital migration rate are presented. We go on to calculate the rate of
+increase of the mean eccentricity for a system of protoplanetary cores due to
+dynamical relaxation. By equating the eccentricity damping time-scale with the
+dynamical relaxation time-scale we deduce that an equilibrium between
+eccentricity damping and excitation through scattering is attained on a 10^3 to
+10^4 yr time-scale, at 1au. The equilibrium thickness of the protoplanet
+distribution is such that it is generally well confined within the gas disc. By
+use of a three dimensional N-body code we simulate the evolution of a system of
+protoplanetary cores, incorporating our eccentricity damping and migration
+rates. Assuming that collisions lead to agglomeration, we find that the
+vertical confinement of the protoplanet distribution permits cores to build up
+from 0.1 to 1 earth mass in only ~10^4 yr, within 1au. The time-scale required
+to achieve this is comparable to the migration time-scale. We deduce that it is
+not possible to build up a massive enough core to form a gas giant planet
+before orbital migration ultimately results in the preferential delivery of all
+such bodies to the neighbourhood of the central star. [Abridged]",9911431v1
+1999-12-14,Finding typical high redshift galaxies with the NOT,"We present results from an ongoing search for galaxy counterparts of a
+subgroup of Quasar Absorption Line Systems called Damped Ly-alpha Absorbers
+(DLAs). DLAs have several characteristics that make them prime candidates for
+being the progenitors of typical present day galaxies.",9912278v1
+2000-10-21,UVES observations of QSO 0000-2620: Argon and Phosphorus abundances in the dust-free damped Ly-alpha system at zabs = 3.3901,"The UV resonance transitions of neutral argon ArI 1066 A, and of singly
+ionized phosphorus PII 963 A, originated in the damped Ly_alpha system (DLA) at
+zabs = 3.3901 towards QSO 0000--2620 have been detected by means of the UVES
+spectrograph at the 8.2m ESO KUEYEN telescope. So far, this is the first
+measurement of ArI, and the second of PII, ever performed in damped galaxies
+and in high redshift objects. This DLA is well known for having one of the
+lowest metal abundances and dust content, and the lowest fractional abundance
+of molecular hydrogen H_2. The measured Ar abundance is [Ar/H] = - 1.91 (+/-
+0.09) which is equal to the abundances of the other alpha-chain elements (O, S
+and Si). The similarity of the Ar abundance with the other alpha-chain elements
+implies the absence of significant photoionization by either UV background or
+stellar sources along the sightline throughout the damped Ly_alpha system. Both
+log(Ar/O) and log(Ar/S) ratios are found close to those measured in the
+extragalactic HII regions and in blue compact galaxies where O is more abundant
+by at least one order of magnitude. This strengthens the universality of the
+Ar/O and Ar/S ratios and lends support to the existence of a universal IMF. The
+abundance of the non-refractory element phosphorus [P/H] = - 2.31 (+/- 0.10)
+confirms the low amount of chemical evolution in the DLA. This is the
+measurement of P in the most metal-poor material and shows a subsolar [P/Fe] =
+--0.27 value. The measured ratios [P/Si] = - 0.40 (+/- 0.13) and [P/S] = - 0.33
+(+/- 0.13) provide evidence for a mild odd-even effect. Finally, a stringent
+upper limit to the population of the 3P_1 level in the ground state of OI is
+derived, which provides a lower limit to the physical dimensions of the zabs =
+3.3901 system of L > 7 pc.",0010434v1
+2001-09-21,Coincidences of high density peaks in UVES spectra of QSO pairs,"We present preliminary results of an investigation of the clustering
+properties of high matter density peaks between redshift ~2 and ~3, as traced
+by Lyman limit and Damped Ly-alpha systems in spectra of close QSO pairs and
+groups.",0109373v1
+2002-12-07,Improved Bounds on Violation of the Strong Equivalence Principle,"I describe a unique, 20-year-long timing program for the binary pulsar
+B0655+64, the stalwart control experiment for measurements of gravitational
+radiation damping in relativistic neutron-star binaries. Observed limits on
+evolution of the B0655+64 orbit provide new bounds on the existence of dipolar
+gravitational radiation, and hence on violation of the Strong Equivalence
+Principle.",0212180v1
+2004-04-13,The Fine-structure Constant as a Probe of Chemical Evolution and AGB Nucleosynthesis in Damped Lyman-alpha Systems,"Evidence from a large sample of quasar absorption-line spectra in damped
+Lyman-alpha systems has suggested a possible time variation of the fine
+structure constant alpha. The most statistically significant portion of this
+sample involves the comparison of Mg and Fe wavelength shifts using the
+many-multiplet (MM) method. However, the sensitivity of this method to the
+abundance of heavy isotopes, especially Mg, is enough to imitate an apparent
+variation in alpha in the redshift range 0.5 < z < 1.8. We implement recent
+yields of intermediate mass (IM) stars into a chemical evolution model and show
+that the ensuing isotope distribution of Mg can account for the observed
+variation in alpha provided the early IMF was particularly rich in intermediate
+mass stars (or the heavy Mg isotope yields from AGB stars are even higher than
+in present-day models). As such, these observations of quasar absorption
+spectra can be used to probe the nucleosynthetic history of low-metallicity
+damped Lyman-alpha systems in the redshift range 0.5 < z < 1.8. This analysis,
+in conjunction with other abundance measurements of low-metallicity systems,
+reinforces the mounting evidence that star formation at low metallicities may
+have been strongly influenced by a population of IM stars. Such IM stars have a
+significant influence on other abundances, particularly nitrogen. We constrain
+our models with independent measurements of N, Si, and Fe in damped Lyman-alpha
+systems as well as C/O in low-metallicity stars. In this way, we obtain
+consistent model parameters for this chemical-evolution interpretation of the
+MM method results.",0404257v2
+2006-01-23,"Bulk viscosity of a gas of neutrinos and coupled scalar particles, in the era of recombination","Bulk viscosity may serve to damp sound waves in a system of neutrinos coupled
+to very light scalar particles, in the era after normal neutrino decoupling but
+before recombination. We calculate the bulk viscosity parameter in a minimal
+scheme involving the coupling of the two systems. We add some remarks on the
+bulk viscosity of a system of fully ionized hydrogen plus photons.",0601525v1
+2006-09-28,Turbulent Comptonization in Relativistic Accretion Disks,"Turbulent Comptonization, a potentially important damping and radiation
+mechanism in relativistic accretion flows, is discussed. Particular emphasis is
+placed on the physical basis, relative importance, and thermodynamics of
+turbulent Comptonization. The effects of metal-absorption opacity on the
+spectral component resulting from turbulent Comptonization is considered as
+well.",0609797v1
+1994-05-16,Bifurcations of two coupled classical spin oscillators,"Two classical, damped and driven spin oscillators with an isotropic exchange
+interaction are considered. They represent a nontrivial physical system whose
+equations of motion are shown to allow for an analytic treatment of local
+codimension 1 and 2 bifurcations. In addition, numerical results are presented
+which exhibit a Feigenbaum route to chaos.",9405011v1
+1998-04-02,The Decay Properties of the Finite Temperature Density Matrix in Metals,"Using ordinary Fourier analysis, the asymptotic decay behavior of the density
+matrix F(r,r') is derived for the case of a metal at a finite electronic
+temperature. An oscillatory behavior which is damped exponentially with
+increasing distance between r and r' is found. The decay rate is not only
+determined by the electronic temperature, but also by the Fermi energy. The
+theoretical predictions are confirmed by numerical simulations.",9804013v1
+1998-12-02,Dissipative properties of vibrated granular materials,"We investigate collective dissipative properties of vibrated granular
+materials by means of molecular dynamics simulations. Rates of energy losses
+indicate three different regimes or ""phases""in the amplitude-frequency plane of
+the external forcing, namely, solid, convective, and gas-like regimes. The
+behavior of effective damping decrement in the solid regime is glassy.
+Practical applications are dicussed.",9812036v1
+1999-01-14,Spin dynamics in the generalized ferromagnetic Kondo model for manganites,"Dynamical spin susceptibility is calculated for the generalized ferromagnetic
+Kondo model which describes itinerant $e_{g}$ electrons interacting with
+localized $t_{2g}$ electrons with antiferromagnetic coupling. The calculations
+done in the mean field approximation show that the spin-wave spectrum of the
+system in ferromagnetic state has two branches, acoustic and optic ones.
+Self-energy corrections to the spectrum are considered and the acoustic
+spin-wave damping is evaluated.",9901141v1
+1999-10-01,Properties of excitations in systems with a spinor Bose-Einstein condensate,"General theory in case of homogenous Bose-Einstein condensed systems with
+spinor condensate is presented for the correlation functions of density and
+spin fluctuations and for the one-particle propagators as well. The random
+phase approximation is investigated and the damping of the modes is given in
+the intermediate temperature region. It is shown that the collective and the
+one-particle excitation spectra do not coincide fully.",9910010v1
+2001-07-16,Anomalous Levy decoherence,"We investigate the decoherence of a small quantum system weakly coupled to a
+complex, chaotic environment when the dynamics is not Gaussian but Levy
+anomalous. By studying the time dependence of the linear entropy and the
+damping of the interference of two Gaussian wave packets in the Wigner
+representation, we show that the decoherence time for a quantum Levy stable
+process is always smaller than for Gaussian diffusion.",0107344v1
+2001-09-05,Nuclear resonant scattering of Synchrotron radiation from nuclei in the Browninan motion,"The time evolution of the coherent forward scattering of Synchrotron
+radiation for resonant nuclei in Brownian motion is studied . Apart from target
+thickness, the appearance of dynamical beats also depends on $\alpha$ which is
+the ratio of harmonic force constant to the damping force constant of a
+harmonic oscillator undergoing Brownian motion.",0109074v2
+2002-03-06,Effect of electron-phonon interaction on the shift and attenuation of optical phonons,"Using the Boltzmann equation for electrons in metals, we show that the
+optical phonons soften and have a dispersion due to screening in agreement with
+the results reported recently [M. Reizer, Phys. Rev. B {\bf 61}, 40 (2000)].
+Additional phonon damping and frequency shift arise when the electron--phonon
+interaction is properly included.",0203112v1
+2002-04-09,Spatial resolution of spin waves in an ultra-cold gas,"We present the first spatially resolved images of spin waves in a gas. The
+complete longitudinal and transverse spin field as a function of time and space
+is reconstructed. Frequencies and damping rates for a standing-wave mode are
+extracted and compared with theory.",0204182v1
+2002-08-14,Three-wave mixing of Bogoliubov quasi-particles in a Bose condensate,"A dressed basis is used to calculate the dynamics of three-wave mixing
+between Bogoliubov quasi-particles in a Bose condensate. Due to the observed
+oscillations between different momenta modes, an energy splitting, analogous to
+the optical Mollow triplet, appears in the Beliaev damping spectrum of the
+excitations from the oscillating modes.",0208283v2
+2002-11-08,"Reply on ``Fluctuation-dissipation considerations for phenomenological damping models for ferromagnetic thin films'' [N. Smith, J. Appl. Phys. \bf{92}, 3877 (2002)]","We show that the critique of our recent papers presented in the
+abovementioned paper (NS) appeals to an incorrect mathematical analogy between
+electrical circuits and linear magnetization dynamics, improperly uses
+classical concepts of normal modes and basic equations, gives inconsistent
+results and therefore comes to incorrect conclusions.",0211147v1
+2003-02-04,Squeezing and temperature measurement in Bose-Einstein Condensates,"In this paper we discuss the presence of temperature-dependent squeezing in
+the collective excitations of trapped Bose-Einstein condensates, based on a
+recent theory of quasiparticle damping. A new scheme to measure temperature
+below the critical temperature is also considered.",0302068v1
+2003-03-12,Time-Dependent Dynamics of the Bose-Fermi Mixed Condensed System,"We study the monopole oscillation in the bose-fermi mixed condensed system by
+performing the time-dependent Gross-Pitaevsky (GP) and Vlasov equations. We
+find that the big damping exists for the fermion oscillation in the mixed
+system even at zero temperature",0303216v1
+2005-10-06,Thermal processes induced in carbon nanotubes by attosecond laser pulses,"In this paper the heat transport in carbon nanotubes is investigated. When
+the dimension of the structure is of the order of the de Broglie wave length
+the transport phenomena must be analyzed within quantum mechanics. In this
+paper we developed the Dirac type thermal equation. The solution of the
+equation the temperature fields for electrons can be damped or can oscillate
+depending on the dynamics of the scattering.",0510141v1
+2006-09-05,Lifetimes of electrons in the Shockley surface state band of Ag(111),"We present a theoretical many-body analysis of the electron-electron (e-e)
+inelastic damping rate $\Gamma$ of electron-like excitations in the Shockley
+surface state band of Ag(111). It takes into account ab-initio band structures
+for both bulk and surface states. $\Gamma$ is found to increase more rapidly as
+a function of surface state energy E than previously reported, thus leading to
+an improved agreement with experimental data.",0609080v1
+2006-09-28,Transition-Event Durations in One Dimensional Activated Processes,"Despite their importance in activated processes, transition-event durations
+-- which are much shorter than first passage times -- have not received a
+complete theoretical treatment. We therefore study the distribution of
+durations of transition events over a barrier in a one-dimensional system
+undergoing over-damped Langevin dynamics.",0609741v1
+2007-01-09,Enhanced Weiss oscillations in graphene,"The magneto-conductivity of a single graphene layer where the electrons are
+described by the Dirac Hamiltonian weakly modulated by a periodic potential is
+calculated. It is shown that Weiss oscillations periodic in the inverse
+magnetic field appear, that are more pronounced and less damped with the
+increment of temperature as compared with the same oscillations in a typical
+two-dimensional electron system with a standard parabolic energy spectrum.",0701175v1
+2007-03-15,A new electromagnetic mode in graphene,"A new, weakly damped, {\em transverse} electromagnetic mode is predicted in
+graphene. The mode frequency $\omega$ lies in the window
+$1.667<\hbar\omega/\mu<2$, where $\mu$ is the chemical potential, and can be
+tuned from radiowaves to the infrared by changing the density of charge
+carriers through a gate voltage.",0703406v1
+1997-04-01,Controversies in the History of the Radiation Reaction problem in General Relativity,"This paper examines the historical controversy over whether gravitationally
+bound systems, such as binary stars, experienced orbital damping due to the
+emission of gravitational radiation, focusing especially on the period of the
+1950s, but also discussing the work of Einstein and Rosen in the 1930s on
+cylindrical gravitational waves and the later quadrupole formula controversy.",9704002v1
+2000-11-14,Binary black holes coalescence: transition from adiabatic inspiral to plunge,"Using two recent techniques giving non-perturbative re-summed estimates of
+the damping and of the conservative part of the dynamics of two-body systems,
+we describe the transition between adiabatic inspiral and plunge in binary
+non-spinning black holes moving along quasi-circular orbits.",0011052v1
+2004-06-24,Hawking temperature from quasi-normal modes,"A perturbed black hole has characteristic frequencies (quasi-normal modes).
+Here I apply a quantum measurement analysis of the quasi-normal mode frequency
+in the limit of high damping. It turns out that a measurement of this mode
+necessarily adds noise to it. For a Schwarzschild black hole, this corresponds
+exactly to the Hawking temperature. The situation for other black holes is
+briefly discussed.",0406097v1
+2005-08-10,Quasinormal modes of Unruh's Acoustic Black Hole,"We have studied the sound perturbation of Unruh's acoustic geometry and we
+present an exact expression for the quasinormal modes of this geometry. We are
+obtain that the quasinormal frequencies are pure-imaginary, that give a purely
+damped modes.",0508040v2
+2005-08-12,Self-similar and charged spheres in the diffusion approximation,"We study spherical, charged and self--similar distributions of matter in the
+diffusion approximation. We propose a simple, dynamic but physically meaningful
+solution. For such a solution we obtain a model in which the distribution
+becomes static and changes to dust. The collapse is halted with damped mass
+oscillations about the absolute value of the total charge.",0508055v1
+2006-12-01,Quasinormal modes of gravitational perturbation around a Schwarzschild black hole surrounded by quintessence,"In this paper, the quasinormal modes of gravitational perturbation around a
+Schwarzschild black hole surrounded by quintessence were evaluated by using the
+third-order WKB approximation. Due to the presence of quintessence, the
+gravitational wave damps more slowly.",0612009v1
+1992-09-14,Lyapunov Exponent of SU(3) Gauge Theory,"The classical SU(3) gauge theory is shown to be deterministic chaotic. Its
+largest Lyapunov exponent is dertermined, from which a short time scale of
+thermalization of a pure gluon system is estimated. The connection to gluon
+damping rate is discussed.",9209018v1
+1993-06-11,Coherence and Decoherence in Radiation off Colliding Heavy Ions,"We discuss the kinetics of a disoriented chiral condensate, treated as an
+open quantum system. We suggest that the problem is analogous to that of a
+damped harmonic oscillator. Master equations are used to establish a hierarchy
+of relevant time scales. Some phenomenological consequences are briefly
+outlined.",9306260v1
+1995-01-06,Thermal Two Point Function of a Heavy Muon in hot QED plasma within Bloch Nordsieck Approximation,"The thermal propagator of a heavy muon propagating in a hot QED plasma is
+examined within the Bloch-Nordsieck approximation, which is valid in the
+infrared region. It is shown that the muon damping rate is finite, in contrast
+to the lower-order calculation with hard thermal loop resummations taken into
+account.",9501223v1
+1997-08-29,Numerical study of plasmon properties in the SU(2)-Higgs model,"We discuss an explorative computation of real time autocorrelation functions,
+in the classical approximation. The results for the `plasmon' frequencies and
+damping rates appear compatible with the divergencies expected from
+perturbation theory.",9708493v1
+1999-07-31,Structure of the Quark Propagator at High Temperature,"In the high temperature, chirally invariant phase of QCD, the quark
+propagator is shown to have two sets of poles with different dispersion
+relations. A reflection property in momentum space relates all derivatives at
+zero-momentum of the particle and hole energies, the particle and hole damping
+rates, and the particle and hole residues. No use is made of perturbation
+theory.",9908204v1
+1999-11-12,Covariant Perturbation Theory of Non-Abelian Kinetic Theory,"A double perturbation idea is presented in framework of the quark-gluon
+plasma kinetic theory. A solvable set of equations from the 'double
+perturbation' is derived and the equations are showed to be gauge-independent.
+The formalism of Landau damping rate for the plasmon at zero momentum is given
+and discussed.",9911325v2
+2000-10-25,Resummation and damping in the O(N) model,"In this talk I summarize the one loop and higher loop calculations of the
+effective equations of motion of the O(N) symmetric scalar model in the linear
+response approximation. At one loop one finds essential difference in long time
+behavior for the fields below and above a dynamically generated length scale. A
+partial resummation assuming quasi-particle propagation seems to cancel the
+relevance of this scale.",0010290v1
+2001-07-16,A generating functional for ultrasoft amplitudes in hot QCD,"The effective amplitudes for gluon momentum p<<gT in hot QCD exhibit damping
+as a result of collisions. The whole set of n-point amplitudes is shown to be
+generated from one functional K(x,y;A), in addition to the induced current
+j(x;A).",0107168v2
+2004-11-01,Brane inflation with dark reheating,"In brane world scenarios inflationary vacuum energy may escape into the
+higher dimensional bulk leaving behind a dark radiation effect on the brane.
+The paper analyses the damping of an inflaton by massless bulk scalar radiation
+and the production of dark radiation in a Randall-Sundrum type of model.",0411021v1
+2005-04-14,Monopolonium in confining phase,"This paper has been withdrawn by the author(s), due the following reasons. A
+similar system for a different purpose has already been studied in
+Phys.Rev.D60:083001,1999 (astro-ph/9904315). Moreover, our analysis was wrong
+because we have missed the large frictional forces that will rapidly damp out
+the energy in the oscillating monopolonium system.",0504108v2
+2005-06-03,MINT - A Simple Model for Low Energy Hadronic Interactions,"The bulk of inelastic hadronic interactions is characterized by longitudinal
+phase space and exponentially damped transverse momentum spectra. A simple
+model with only a single adjustable parameter is presented, making it a very
+convenient tool for systematic studies, which gives a surprisingly good
+description of pA-collisions at 920 GeV beam energy.",0506028v1
+1996-05-17,Non-Abelian Kubo Formula and the Multiple Time-Scale Method,"The non-Abelian Kubo formula is derived from the kinetic theory. That
+expression is compared with the one obtained using the eikonal for a
+Chern-Simons theory. The multiple time-scale method is used to solve the
+non-Abelian Kubo formula, and the damping rate for longitudinal color waves is
+computed.",9605120v1
+1996-10-02,Self-consistent determination of hard modes in hot QCD,"We determine self-consistently the hard-quark and hard-gluon modes in hot
+QCD. The damping-rate part in resummed hard-quark or hard-gluon propagators,
+rather than the thermal-mass part, plays the dominant role.",9610010v1
+2000-11-06,Note on Open String/D-brane System and Noncommutative Soliton,"This is a summary of a series of papers hep-th/9910263,0005283,0010066
+written with B. Chen, T. Matsuo and K. Murakami on a p-p', (p<p^{\prime}) open
+string with B_{ij} field, which has led us to the explicit identification of
+the Dp-brane with the noncommutative projector soliton via the gaussian damping
+factor. A lecture given at Summer Institute 2000, FujiYoshida, Yamanashi,
+Japan, at August 7-14, 2000.",0011028v1
+2002-10-11,A simple mechanical analog of the field theory of tachyon matter,"In this brief note we show that the zero dimensional version of the field
+theory of tachyon matter proposed by Sen, provides an action integral
+formulation for the motion of a particle in the presence of Newtonian gravity
+and nonlinear damping (quadratic in velocity).",0210108v2
+2003-07-01,Highly damped quasinormal modes of Kerr black holes,"Motivated by recent suggestions that highly damped black hole quasinormal
+modes (QNM's) may provide a link between classical general relativity and
+quantum gravity, we present an extensive computation of highly damped QNM's of
+Kerr black holes. We do not limit our attention to gravitational modes, thus
+filling some gaps in the existing literature. The frequency of gravitational
+modes with l=m=2 tends to \omega_R=2 \Omega, \Omega being the angular velocity
+of the black hole horizon. If Hod's conjecture is valid, this asymptotic
+behaviour is related to reversible black hole transformations. Other highly
+damped modes with m>0 that we computed do not show a similar behaviour. The
+real part of modes with l=2 and m<0 seems to asymptotically approach a constant
+value \omega_R\simeq -m\varpi, \varpi\simeq 0.12 being (almost) independent of
+a. For any perturbing field, trajectories in the complex plane of QNM's with
+m=0 show a spiralling behaviour, similar to the one observed for
+Reissner-Nordstrom (RN) black holes. Finally, for any perturbing field, the
+asymptotic separation in the imaginary part of consecutive modes with m>0 is
+given by 2\pi T_H (T_H being the black hole temperature). We conjecture that
+for all values of l and m>0 there is an infinity of modes tending to the
+critical frequency for superradiance (\omega_R=m) in the extremal limit.
+Finally, we study in some detail modes branching off the so--called
+``algebraically special frequency'' of Schwarzschild black holes. For the first
+time we find numerically that QNM multiplets emerge from the algebraically
+special Schwarzschild modes, confirming a recent speculation.",0307013v2
+2004-01-22,Noncommutative inflation and the large-scale damping in the CMB anisotropy,"We show that a certain class of short-distance cutoff can give rise to large
+suppression on the CMB anisotropies at large angular scales.",0401153v2
+2006-05-19,Energy Loss of Heavy Quarks from Asymptotically AdS Geometries,"We investigate some universal features of AdS/CFT models of heavy quark
+energy loss. In addition, as a specific example, we examine quark damping in
+the spinning D3-brane solution dual to N=4 SU(N_c) super Yang-Mills at finite
+temperature and R-charge chemical potential.",0605191v2
+2003-06-30,Damped oscillatory integrals and boundedness of maximal operators associated to mixed homogeneous hypersurfaces,"We study the boundedness problem for maximal operators in 3-dimensional
+Euclidean space associated to hypersurfaces given as the graph of $c+f$, where
+$f$ is a mixed homogeneous function which is smooth away from the origin and
+$c$ is a constant. Our result generalizes a corresponding theorem on mixed
+homogeneous polynomial functions by A. Iosevich and E. Sawyer.",0306429v1
+2003-12-19,Energy Decay of Damped Systems,"We present a new and simple bound for the exponential decay of second order
+systems using the spectral shift. This result is applied to finite matrices as
+well as to partial differential equations of Mathematical Physics. The type of
+the generated semigroup is shown to be bounded by the upper real part of the
+numerical range of the underlying quadratic operator pencil.",0312376v1
+2006-12-07,Fractional Hamiltonian analysis of higher order derivatives systems,"The fractional Hamiltonian analysis of 1+1 dimensional field theory is
+investigated and the fractional Ostrogradski's formulation is obtained. The
+fractional path integral of both simple harmonic oscillator with an
+acceleration-squares part and a damped oscillator are analyzed. The classical
+results are obtained when fractional derivatives are replaced with the integer
+order derivatives.",0612024v1
+2000-05-18,Environment-induced dynamical chaos,"We examine the interplay of nonlinearity of a dynamical system and thermal
+fluctuation of its environment in the ``physical limit'' of small damping and
+slow diffusion in a semiclassical context and show that the trajectories of
+c-number variables exhibit dynamical chaos due to the thermal fluctuations of
+the bath.",0005037v1
+2003-02-12,On Whitham theory for perturbed integrable equations,"Whitham theory of modulations is developed for periodic waves described by
+nonlinear wave equations integrable by the inverse scattering transform method
+associated with $2\times2$ matrix or second order scalar spectral problems. The
+theory is illustrated by derivation of the Whitham equations for perturbed
+Korteweg-de Vries equation and nonlinear Schr\""odinger equation with linear
+damping.",0302027v1
+2003-02-24,Reverse Integration for Computing Stationary Points of Unstable Stiff Systems,"Using existing, forward-in-time integration schemes, we demonstrate that it
+is possible to compute unstable, saddle-type fixed points of stiff systems of
+ODEs when the stable compenents are fast (i.e., rapidly damped) while the
+unstable components are slow. The approach has implications for the reverse
+(backward in time) integration of such stiff systems, and for the coarse
+reverse integration of microscopic/stochastic simulations.",0302055v1
+2003-09-02,Breather lattice and its stabilization for the modified Korteweg-de Vries equation,"We obtain an exact solution for the breather lattice solution of the modified
+Korteweg-de Vries (MKdV) equation. Numerical simulation of the breather lattice
+demonstrates its instability due to the breather-breather interaction. However,
+such multi-breather structures can be stabilized through the concurrent
+application of ac driving and viscous damping terms.",0309003v1
+2003-12-19,Existence of travelling waves in discrete sine-Gordon rings,"We prove existence results for travelling waves in discrete, damped,
+dc-driven sine-Gordon equations with periodic boundary conditions.",0312042v5
+2006-12-05,Colliding Particles in Highly Turbulent Flows,"We discuss relative velocities and the collision rate of small particles
+suspended in a highly turbulent fluid. In the limit where the viscous damping
+is very weak, we estimate the relative velocities using the Kolmogorov cascade
+principle.",0612008v2
+1999-06-08,Electromagnetic modes in cold magnetized strongly coupled plasmas,"The spectrum of electromagnetic waves propagating in a strongly coupled
+magnetized fully ionized hydrogen plasma is found. The ion motion and damping
+being neglected, the influence of the Coulomb coupling on the electromagnetic
+spectrum is analyzed.",9906016v1
+2000-08-12,The effects of the rotation in plasma,"Electric and magnetic self-fields can exist in the rotating plasma. A
+self-sustained rotation can be established in the plasma. The disturbed
+distribution function of rotating plasma is derived from the Vlasov equation.
+The propagation of waves in rotating plasma differs from that in the usual
+plasma. New terms for Landau damping appear. The local rotational behaviour may
+become prevailing.",0008039v1
+2000-12-11,An improved empirical equation for bunch lengthening in electron storage rings,"In this paper we propose an improved empirical equation for the bunch
+lengthening in electron storage rings. The comparisons are made between the
+analytical and experimental results, and the agreements are quite well. This
+improved equation can be equally applied to the case where a storage ring is
+very resistive (such as the improved SLC damping rings) instead of inductive as
+usual.",0012020v2
+2001-07-25,Causal Classical Theory of Radiation Damping,"It is shown how initial conditions can be appropriately defined for the
+integration of Lorentz-Dirac equations of motion. The integration is performed
+\QTR{it}{forward} in time. The theory is applied to the case of the motion of
+an electron in an intense laser pulse, relevant to nonlinear Compton
+scattering.",0107062v1
+2001-11-26,Methods of Laser Cooling of Electron Beams in Storage Rings,"Methods of enhanced laser cooling of particle beams in storage rings and
+Robinson's damping criterion are discussed. The dynamics of amplitudes of
+betatron oscillations and instantaneous orbits of electrons interacting with
+laser beams being displaced in the radial direction is investigated.",0111184v2
+2002-04-17,Soliton self-modulation of the turbulence amplitude and plasma rotation,"The space-uniform amplitude envelope of the Ion Temperature Gradient driven
+turbulence is unstable to small perturbations and evolves to nonuniform,
+soliton-like modulated profiles. The induced poloidal asymmetry of the
+transport fluxes can generate spontaneous poloidal spin-up of the tokamak
+plasma.",0204050v2
+2002-05-06,Delayed Equation for Charged Rigid Nonrelativistic Ball,"Simple expression for self-force acting on radiating rigid charged ball is
+derived (Sommerfeld ball). It is shown that appropriate delayed equation of
+motion has solutions in general differ from that for Sommerfeld sphere - there
+are no ""radiationless"" solutions, but there are oscillating without damping
+solutions though self-force has nonzero value.",0205012v1
+2004-09-03,Relativistic electron beam acceleration by Compton scattering of lower-hybrid waves,"It has been proved theoetically and numerically that the highly relativistic
+electron beam can be accelerated efficiently via the Compton scattering induced
+by nonlinear Landau and cyclotron damping of the lower-hybrid waves.",0409024v1
+2000-01-08,Quantum computation with mesoscopic superposition states,"We present a strategy to engineer a simple cavity-QED two-bit universal
+quantum gate using mesoscopic distinct quantum superposition states. The
+dissipative effect on decoherence and amplitude damping of the quantum bits are
+analyzed and the critical parameters are presented.",0001018v1
+2001-10-03,Thermal and quantum noise in active systems,"We present a quantum network approach to the treatment of thermal and quantum
+fluctuations in measurement devices. The measurement is described as a
+scattering process of input fluctuations towards output ones. We present the
+results obtained with this method for the treatment of a cold damped capacitive
+accelerometer.",0110021v1
+2001-11-24,Deformed versus undeformed cat states encoding qubit,"We study the possibility of exploiting superpositions of coherent states to
+encode qubit. A comparison between the use of deformed and undeformed bosonic
+algebra is made in connection with the amplitude damping errors.",0111128v1
+2002-11-05,Unitary reduction of the Liouville equation relative to a two-level atom coupled to a bimodal lossy cavity,"The Liouville equation of a two-level atom coupled to a degenerate bimodal
+lossy cavity is unitarily and exactly reduced to two uncoupled Liouville
+equations. The first one describes a dissipative Jaynes-Cummings model and the
+other one a damped harmonic oscillator. Advantages related to the reduction
+method are discussed.",0211015v1
+2003-11-10,Cavity Assisted Nondestructive Laser Cooling of Atomic Qubits,"We analyze two configurations for laser cooling of neutral atoms whose
+internal states store qubits. The atoms are trapped in an optical lattice which
+is placed inside a cavity. We show that the coupling of the atoms to the damped
+cavity mode can provide a mechanism which leads to cooling of the motion
+without destroying the quantum information.",0311054v2
+2003-11-19,Noise enhancing the classical information capacity of a quantum channel,"We present a simple model of quantum communication where a noisy quantum
+channel may benefit from the addition of further noise at the decoding stage.
+We demonstrate enhancement of the classical information capacity of an
+amplitude damping channel, with a predetermined detection threshold, by the
+addition of noise in the decoding measurement.",0311126v1
+2003-12-22,Observation of Exceptional Points in Electronic Circuits,"Two damped coupled oscillators have been used to demonstrate the occurrence
+of exceptional points in a purely classical system. The implementation was
+achieved with electronic circuits in the kHz-range. The experimental results
+perfectly match the mathematical predictions at the exceptional point. A
+discussion about the universal occurrence of exceptional points -- connecting
+dissipation with spatial orientation -- concludes the paper.",0312182v1
+2004-08-01,Remark on the additivity conjecture for the quantum depolarizing channel,"We consider bistochastic quantum channels generated by unitary
+representations of the discret group. The proof of the additivity conjecture
+for the quantum depolarizing channel $\Phi$ based on the decreasing property of
+the relative entropy is given. We show that the additivity conjecture is true
+for the channel $\Xi =\Psi \circ \Phi $, where $\Psi $ is the phase damping.",0408004v2
+2005-03-26,Markovian feedback to control continuous variable entanglement,"We present a model to realize quantum feedback control of continuous variable
+entanglement. It consists of two interacting bosonic modes subject to amplitude
+damping and achieving entangled Gaussian steady state. The possibility to
+greatly improve the degree of entanglement by means of Markovian (direct)
+feedback is then shown.",0503206v2
+2005-04-12,Generation of Werner states and preservation of entnglement in a noisy environment,"We study the influence of noisy environment on the evolution of two-atomic
+system in the presence of collective damping. Generation of Werner states as
+asymptotic states of evolution is described. We also show that for some initial
+states the amount of entanglement is preserved during the evolution.",0504090v2
+2005-04-25,Dissipative dynamics of nondegenerate two-photon Jaynes-Cummings model,"A nondegenerate two-photon Jaynes-Cummings model is investigated where the
+leakage of photon through the cavity is taken into account. The effect of
+cavity damping on the mean photon number, atomic populations, field statistics
+and both field and atomic squeezing is considered on the basis of master
+equation in dressed-state approximation for initial coherent fields and excited
+atom.",0504184v1
+2005-07-20,A minimal coupling method for dissipative quantum systems,"Quantum dynamics of a general dissipative system investigated by its coupling
+to a Klein-Gordon type field as the environment by introducing a minimal
+coupling method. As an example, the quantum dynamics of a damped three
+dimensional harmonic oscillator investigated and some transition probabilities
+indicating the way energy flows between the subsystems obtained. The quantum
+dynamics of a dissipative two level system considered.",0507195v1
+2007-02-09,Linear-optics manipulations of photon-loss codes,"We discuss codes for protecting logical qubits carried by optical fields from
+the effects of amplitude damping, i.e. linear photon loss. We demonstrate that
+the correctability condition for one-photon loss imposes limitations on the
+range of manipulations than can be implemented with passive linear-optics
+networks.",0702091v1
+2007-08-27,Band-Gap Engineering of Phononic Crystals: A Computational Survey of Two-Dimensional Systems,"We present graphic results with high-levels of abstraction to desribe the
+basic principles and rules of thumb for acoustic or phononic band-gap
+engineering. We use these rules for developing an improved machien mount for
+damping acoustic vibrations, a phononic lens and a frequency selective filter
+in the acoustic regime.",0708.3669v1
+2007-09-01,Comments on 'Controversy on a Dispersion Relation for MHD Waves' by Chandra and Kumthekar,"We comment on the work by Chandra and Kumthekar (2007, henceforth CK) which
+is questionable. In the derivation of dispersion relation, CK neither invoke
+the concept of vector space nor do they follow the basic criterion for the
+elimination of perturbation terms under which the damped magnetoacoustic waves
+are derived.",0709.0040v1
+2007-09-17,Intrinsic dissipation in cantilevers,"We consider the effects of a velocity-independent friction force on
+cantilever damping. It is shown that this dissipation mechanism causes
+nonlinear effects in the cantilever vibrations. The size of the nonlinearity
+increases with decreasing cantilever velocity. Our analysis makes it possible
+to understand experiments [Stipe et al, PRL 87, 096801 (2001)] where an
+amplitude dependence of the cantilever eigenfrequency and anomalous dissipation
+was observed only at small amplitudes.",0709.2582v1
+2007-09-21,Enhanced Optical Cooling of Particle Beams in Storage Rings,"A method of enhanced optical cooling (EOC) based on nonlinear selective
+interaction between particles and theirs amplified undulator radiation wavelets
+(URW) in storage rings is discussed. It leads to non-exponential fast damping.
+The selectivity is arranged by a moving screen located on the image plane of
+the optical system projecting URW there.",0709.3403v1
+2007-10-26,Vacuum - induced stationary entanglement in radiatively coupled three - level atoms,"We consider a pair of three - level atoms interacting with a common vacuum
+and analyze the process of entanglement production due to spontaneous emission.
+We show that in the case of closely separated atoms, collective damping can
+generate robust entanglement of the asymptotic states.",0710.5048v2
+2008-04-21,Resonant excitation amidst dephasing: An exact analytic solution,"An exact analytic solution is presented for coherent resonant excitation of a
+two-state quantum system driven by a time-dependent pulsed external field with
+a hyperbolic-secant shape in the presence of dephasing. Analytic results are
+derived for the amplitude and the phase shift of the damped Rabi oscillations.",0804.3315v1
+2008-05-06,Logarithmic decay of hyperbolic equations with arbitrary boundary damping,"In this paper, we study the logarithmic stability for the hyperbolic
+equations by arbitrary boundary observation. Based on Carleman estimate, we
+first prove an estimate of the resolvent operator of such equation. Then we
+prove the logarithmic stability estimate for the hyperbolic equations without
+any assumption on an observation subboundary.",0805.0625v1
+2008-07-14,A z = 3 Lyman Alpha Blob Associated with a Damped Lyman Alpha System Proximate to its Background Quasar,"We report on the discovery of a bright Lyman alpha blob associated with the
+z=3 quasar SDSSJ124020.91+145535.6 which is also coincident with strong damped
+Lyman alpha absorption from a foreground galaxy (a so-called proximate damped
+Lyman alpha system; PDLA). The one dimensional spectrum acquired by the Sloan
+Digital Sky Survey (SDSS) shows a broad Lyman alpha emission line with a FWHM ~
+500 km/s and a luminosity of L_{Lya} = 3.9e43 erg/s superposed on the trough of
+the PDLA. Mechanisms for powering this large Lyman alpha luminosity are
+discussed. We argue against emission from HII regions in the PDLA galaxy since
+this requires an excessive star-formation rate ~ 500 Msun/yr and would
+correspond to the largest Lyman alpha luminosity ever measured from a damped
+Lyman alpha system or starburst galaxy. We use a Monte Carlo radiative transfer
+simulation to investigate the possibility that the line emission is fluorescent
+recombination radiation from the PDLA galaxy powered by the ionizing flux of
+the quasar, but find that the predicted Lyman alpha flux is several orders of
+magnitude lower than observed. We conclude that the Lyman alpha emission is not
+associated with the PDLA galaxy at all, but instead is intrinsic to the
+quasar's host and similar to the extended Lyman alpha 'fuzz' which is detected
+around many AGN. PDLAs are natural coronagraphs that block their background
+quasar at Lyman alpha, and we discuss how systems similar to
+SDSSJ124020.91+145535.6 might be used to image the neutral hydrogen in the PDLA
+galaxy in silhouette against the screen of extended Lyman alpha emission from
+the background quasar.",0807.2271v1
+2008-09-23,Analysis of complete positivity conditions for quantum qutrit channels,"We present an analysis of complete positivity (CP) constraints on qutrit
+quantum channels that have a form of affine transformations of generalized
+Bloch vector. For diagonal (damping) channels we derive conditions analogous to
+the ones that in qubit case produce tetrahedron structure in the channel
+parameter space.",0809.3882v3
+2008-10-28,Excitation and damping of p-mode oscillations of alpha Cen B,"This paper presents an analysis of observational data on the p-mode spectrum
+of the star alpha Cen B and a comparison with theoretical computations of the
+stochastic excitation and damping of the modes. We find that at frequencies >
+4500 micro-Hz, the model damping rates appear to be too weak to explain the
+observed shape of the power spectral density of alpha Cen B. The conclusion
+rests on the assumption that most of the disagreement is due to problems
+modelling the damping rates, not the excitation rates, of the modes. This
+assumption is supported by a parallel analysis of BiSON Sun-as-a-star data, for
+which it is possible to use analysis of very long timeseries to place tight
+constraints on the assumption. The BiSON analysis shows that there is a similar
+high-frequency disagreement between theory and observation in the Sun.
+  We demonstrate that by using suitable comparisons of theory and observation
+it is possible to make inference on the dependence of the p-mode linewidths on
+frequency, without directly measuring those linewidths, even though the alpha
+Cen B dataset is only a few nights long. Use of independent measures from a
+previous study of the alpha Cen B linewidths in two parts of its spectrum also
+allows us to calibrate our linewidth estimates for the star. The resulting
+calibrated linewidth curve looks similar to a frequency-scaled version of its
+solar cousin, with the scaling factor equal to the ratio of the respective
+acoustic cut-off frequencies of the two stars. The ratio of the frequencies at
+which the onset of high-frequency problems is seen in both stars is also given
+approximately by the same scaling factor.",0810.5022v1
+2008-11-03,Equation of state for QCD matter in a quasiparticle model,"A phenomenological QCD quasiparticle model provides a means to map lattice
+QCD results to regions relevant for a variety of heavy-ion collision
+experiments at larger baryon density. We report on effects of collectives modes
+and damping on the equation of state.",0811.0274v1
+2009-01-14,On the use of continuous wavelet analysis for modal identification,"This paper reviews two different uses of the continuous wavelet transform for
+modal identification purposes. The properties of the wavelet transform, mainly
+energetic, allow to emphasize or filter the main information within measured
+signals and thus facilitate the modal parameter identification especially when
+mechanical systems exhibit modal coupling and/or relatively strong damping.",0901.2000v1
+2009-01-20,Quasi-periodic motions in strongly dissipative forced systems,"We consider a class of ordinary differential equations describing
+one-dimensional systems with a quasi-periodic forcing term and in the presence
+of large damping. We discuss the conditions to be assumed on the mechanical
+force and the forcing term for the existence of quasi-periodic solutions which
+have the same frequency vector as the forcing.",0901.3009v1
+2009-01-23,On the regularity of global attractors,"This note is focused on a novel technique in order to establish the
+boundedness in more regular spaces for global attractors of dissipative
+dynamical systems, without appealing to uniform-in-time estimates. As an
+application of the abstract result, the semigroup generated by the strongly
+damped wave equation $$u_{tt}-\Delta u_t-\Delta u+\phi(u)=f$$ with critical
+nonlinearity is considered, whose attractor is shown to possess the optimal
+regularity.",0901.3607v1
+2009-05-07,On a Stochastic Wave Equation Driven by a Non-Gaussian Levy Process,"This paper investigates a damped stochastic wave equation driven by a
+non-Gaussian Levy noise. The weak solution is proved to exist and be unique.
+Moreover we show the existence of a unique invariant measure associated with
+the transition semigroup under mild conditions.",0905.0992v1
+2009-05-07,Metal-Enriched Plasma in Protogalactic Halos: A Survey of N V Absorption in High-z Damped & Sub-Damped Lyman-alpha Systems,"We continue our recent work to characterize the plasma content of
+high-redshift damped and sub-damped Lyman-alpha systems (DLAs/sub-DLAs), which
+represent multi-phase gaseous (proto)galactic disks and halos seen toward a
+background source. We survey N V absorption in a sample of 91 DLAs and 18
+sub-DLAs in the redshift range 1.67<z<4.28 with unblended coverage of the N V
+doublet, using data from VLT/UVES, Keck/HIRES, and Keck/ESI. In DLAs, we find
+eight secure N V detections, four marginal detections, and 79 non-detections.
+The detection rate of N V in DLAs is therefore 13^{+5}_{-4}%. Two sub-DLA N V
+detections are found among a sample of 18, at a similar detection rate of
+11^{+15}_{-7}%. We show that the N V detection rate is a strong function of
+metallicity, increasing by a factor of ~4 at [N/H]=[NI/HI]>-2.3. The N V and
+CIV component b-value distributions in DLAs are statistically similar, but the
+median b(N V) of 18 km/s is lower than the median b(O VI) of 25 km/s. Some ~20%
+of the N V components have b<10 km/s and thus arise in warm photoionized plasma
+at log (T/K)<4.92; local sources of ionizing radiation (as opposed to the
+extragalactic background) are required to keep the cloud sizes physically
+reasonable. The nature of the remaining ~80% of (broad) N V components is
+unclear; models of radiatively-cooling collisionally-ionized plasma at
+log(T/K)=5.2-5.4 are fairly successful in reproducing the observed integrated
+high-ion column density ratios and the component line widths, but we cannot
+rule out photoionization by local sources. Finally, we identify several unusual
+DLAs with extremely low metallicity (<0.01 solar) but strong high-ion
+absorption [log N(N V)>14 or log N(O VI)>14.2] that present challenges to
+either galactic inflow or outflow models.",0905.1042v2
+2009-05-12,Quantum measurement with chaotic apparatus,"We study a dissipative quantum mechanical model of the projective measurement
+of a qubit. We demonstrate how a correspondence limit, damped quantum
+oscillator can realise chaotic-like or periodic trajectories that emerge in
+sympathy with the projection of the qubit state, providing a model of the
+measurement process.",0905.1867v2
+2009-06-12,Tailoring the carrier mobility of semiconducting nanowires by remote dielectrics,"The dielectric environment of thin semiconductor nanowires can affect the
+charge transport properties inside the wire. In this work, it is shown that
+Coulomb impurity scattering inside thin nanowires can be damped strongly by
+coating the wire with a high-k dielectric. This will lead to an increase in the
+mobility of free charges inside the wire.",0906.2371v1
+2009-10-22,Modelling collisions in a relativistic plasma,"Generalising the work of Lenard and Bernstein, we introduce a new, fully
+relativistic model to describe collisional plasmas. Like the Fokker-Planck
+operator, this equation represents velocity diffusion and conserves particle
+number. However, unlike the Fokker-Planck operator it is linear in the
+distribution function, and so more amenable to a fluid treatment. By taking
+moments, we derive a new fluid model, and demonstrate the damping effects of
+collisions on Langmuir waves.",0910.4368v1
+2009-11-24,Non-Markovian master equation for a damped driven two-state system,"We present a detailed microscopic derivation for a non-Markovian master
+equation for a driven two-state system interacting with a general structured
+reservoir. The master equation is derived using the time-convolutionless
+projection operator technique in the limit of weak coupling between the
+two-state quantum system and its environment. We briefly discuss the Markov
+approximation, the secular approximation and their validity.",0911.4600v1
+2009-12-07,Analyticity and Gevrey-class regularity for the second-grade fluid equations,"We address the global persistence of analyticity and Gevrey-class regularity
+of solutions to the two and three-dimensional visco-elastic second-grade fluid
+equations. We obtain an explicit novel lower bound on the radius of analyticity
+of the solutions to the second-grade fluid equations that does not vanish as
+$t\to \infty$. Applications to the damped Euler equations are given.",0912.1327v1
+2010-02-15,Analysis on Path Spaces over Riemmannian Manifolds with Boundary,"By using Hsu's multiplicative functional for the Neumann heat equation, a
+natural damped gradient operator is defined for the reflecting Brownian motion
+on compact manifolds with boundary. This operator is linked to quasi-invariant
+flows in terms of a integration by parts formula, which leads to the standard
+log-Sobolev inequality for the associated Dirichlet form on the path space.",1002.2887v1
+2010-03-07,Decay of Langmuir wave in dense plasmas and warm dense matter,"The decays of the Langmuir waves in dense plasmas are computed using the
+dielectric function theory widely used in the solid state physics.
+  Four cases are considered: a classical plasma, a Maxwellian plasma, a
+degenerate quantum plasma, and a partially degenerate plasma. The result is
+considerably different from the conventional Landau damping theory.",1003.1524v2
+2010-05-20,Cavity spin optodynamics,"The dynamics of a large quantum spin coupled parametrically to an optical
+resonator is treated in analogy with the motion of a cantilever in cavity
+optomechanics. New spin optodynamic phenonmena are predicted, such as
+cavity-spin bistability, optodynamic spin-precession frequency shifts, coherent
+amplification and damping of spin, and the spin optodynamic squeezing of light.",1005.3853v2
+2011-02-21,Noncommutative gauge theory and renormalisability,"We review two different noncommutative gauge models generalizing approaches
+which lead to renormalizable scalar quantum field theories. One of them
+implements the crucial IR damping of the gauge field propagator in the
+so-called ``soft breaking'' part. We discuss one-loop renormalisability.",1102.4167v1
+2011-04-10,Stabilization of the wave equation with external force,"We study the rate of decay of the energy functional of solutions of the wave
+equation with localized damping and a external force. We prove that the decay
+rates of the energy functional is determined from a forced differential
+equation.",1104.1808v3
+2011-05-01,"Set, Reset, and Retention Times for Ionic and Filamentary Mem-Resistors","A dynamic systems model has previously been proposed for mem-resistors based
+on a driven damped harmonic oscillator differential equation describing
+electron and ionic depletion widths in a thin semiconductor film. This paper
+derives equations for set, reset, and retention times based on the previously
+proposed model. Keywords- mem-resistor, RRAM, ReRAM",1105.0134v3
+2011-07-30,Ion-kinetic D'Angelo mode,"An extension of hydrodynamic D'Angelo mode of inhomogeneous sheared plasma
+flow along the magnetic field into the short-wavelength limit, where the
+hydrodynamic treatment is not valid, has been considered. We find that D'Angelo
+mode in this wavelength range is excited by inverse ion Landau damping and
+becomes the shear flow driven ion-kinetic mode.",1108.0093v1
+2011-11-14,Twist of fractional oscillations,"Using the method of the Laplace transform, we consider fractional
+oscillations. They are obtained by the time-clock randomization of ordinary
+harmonic vibrations. In contrast to sine and cosine, the functions describing
+the fractional oscillations exhibit a finite number of damped oscillations with
+an algebraic decay. Their fractional differential equation is derived.",1111.5298v1
+2011-12-02,On the transmission of binary bits in discrete Josephson-junction arrays,"In this work, we use supratransmission and infratransmission in the
+mathematical modeling of the propagation of digital signals in weakly damped,
+discrete Josephson-junction arrays, using energy-based detection criteria. Our
+results show an efficient and reliable transmission of binary information.",1112.0589v1
+2012-01-12,Superconducting elliptical cavities,"We give a brief overview of the history, state of the art, and future for
+elliptical superconducting cavities. Principles of the cell shape optimization,
+criteria for multi-cell structures design, HOM damping schemes and other
+features are discussed along with examples of superconducting structures for
+various applications.",1201.2598v1
+2012-02-19,Cluster-based Superconducting Tunneling Networks,"A 2D tunneling network consisting of nanoclusters placed on a surface is
+studied. It is shown that such a network is capable of transferring large
+supercurrent at high temperatures. For a realistic set of parameters the
+damping is quite small, and the smallness is due to strong renormalization of
+the capacitance of a cluster. The critical field also turns out to be lar",1202.4132v1
+2012-02-25,Design of a Fractional Order Phase Shaper for Iso-damped Control of a PHWR under Step-back Condition,"Phase shaping using fractional order (FO) phase shapers has been proposed by
+many contemporary researchers as a means of producing systems with iso-damped
+closed loop response due to a stepped variation in input. Such systems, with
+the closed loop damping remaining invariant to gain changes can be used to
+produce dead-beat step response with only rise time varying with gain. This
+technique is used to achieve an active step-back in a Pressurized Heavy Water
+Reactor (PHWR) where it is desired to change the reactor power to a
+pre-determined value within a short interval keeping the power undershoot as
+low as possible. This paper puts forward an approach as an alternative for the
+present day practice of a passive step-back mechanism where the control rods
+are allowed to drop during a step-back action by gravity, with release of
+electromagnetic clutches. The reactor under a step-back condition is identified
+as a system using practical test data and a suitable Proportional plus Integral
+plus Derivative (PID) controller is designed for it. Then the combined plant is
+augmented with a phase shaper to achieve a dead-beat response in terms of power
+drop. The fact that the identified static gain of the system depends on the
+initial power level at which a step-back is initiated, makes this application
+particularly suited for using a FO phase shaper. In this paper, a model of a
+nuclear reactor is developed for a control rod drop scenario involving rapid
+power reduction in a 500MWe Canadian Deuterium Uranium (CANDU) reactor using
+AutoRegressive Exogenous (ARX) algorithm. The system identification and reduced
+order modeling are developed from practical test data. For closed loop active
+control of the identified reactor model, the fractional order phase shaper
+along with a PID controller is shown to perform better than the present Reactor
+Regulating System (RRS) due to its iso-damped nature.",1202.5657v1
+2012-02-27,Simple absorbing boundary conditions for wave simulations with Smoothed Particle Hydrodynamics,"We study and implement a simple method, based on the Perfectly Matched Layer
+approach, to treat non reflecting boundary conditions with the Smoothed
+Particles Hydrodynamics numerical algorithm. The method is based on the concept
+of physical damping. We illustrate how it works in the case of 1D and 2D time
+dependent waves propagating in a finite domain.",1202.5893v1
+2012-07-22,Singularity and existence to a wave system of nematic liquid crystals,"In this paper, we prove the global existence and singularity formation for a
+wave system from modelling nematic liquid crystals in one space dimension. In
+our model, although the viscous damping term is included, the solution with
+smooth initial data still has gradient blowup in general, even when the initial
+energy is arbitrarily small.",1207.5190v1
+2012-07-26,Upsilon Suppression in PbPb Collisions at sqrt(s_NN) = 2.76 TeV,"We suggest that the combined effect of screening, gluon-induced dissociation,
+collisional damping, and reduced feed-down explains most of the sequential
+suppression of Y(nS) states that has been observed in PbPb relative to pp
+collisions at sqrt(s_NN) = 2.76 TeV. The suppression is thus a clear, albeit
+indirect, indication for the presence of a qgp.",1207.6227v1
+2012-09-08,Local energy decay for the wave equation with nonlinear time dependent damping,"This paper addresses a wave equation on a exterior domain in R^{d}(d odd)
+with nonlinear time dependent dissipation. Under a microlocal geometric
+condition we prove that the decay rates of the local energy functional are
+obtained by solving a nonlinear non-autonomous differential equation.",1209.1733v1
+2012-09-08,Evidence for anisotropic polar nanoregions in relaxor PMN: A neutron study of the elastic constants and anomalous TA phonon damping,"We use neutron scattering to characterize the acoustic phonons in the relaxor
+PMN and demonstrate the presence of an anisotropic damping mechanism directly
+related to short-range, polar correlations. For a large range of temperatures
+above Tc ~ 210, K, where dynamic polar correlations exist, acoustic phonons
+propagating along [1\bar{1}0] and polarized along [110] (TA2 phonons) are
+overdamped and softened across most of the Brillouin zone. By contrast,
+acoustic phonons propagating along [100] and polarized along [001] (TA1
+phonons) are overdamped and softened for only a limited range of wavevectors.
+The anisotropy and temperature dependence of the acoustic phonon energy
+linewidth are directly correlated with the elastic diffuse scattering,
+indicating that polar nanoregions are the cause of the anomalous behavior. The
+damping and softening vanish for q -> 0, i.e. for long-wavelength acoustic
+phonons, which supports the notion that the anomalous damping is a result of
+the coupling between the relaxational component of the diffuse scattering and
+the harmonic TA phonons. Therefore, these effects are not due to large changes
+in the elastic constants with temperature because the elastic constants
+correspond to the long-wavelength limit. We compare the elastic constants we
+measure to those from Brillouin scattering and to values reported for pure PT.
+We show that while the values of C44 are quite similar, those for C11 and C12
+are significantly less in PMN and result in a softening of (C11-C12) over PT.
+There is also an increased elastic anisotropy (2C44/(C11-C12)) versus that in
+PT. These results suggest an instability to TA2 acoustic fluctuations in
+relaxors. We discuss our results in the context of the debate over the
+""waterfall"" effect and show that they are inconsistent with TA-TO phonon
+coupling or other models that invoke the presence of a second optic mode.",1209.1736v1
+2012-12-28,Turbulence-Induced Instabilities in EP and QGP,"Polarization properties of turbulent stochastically inhomogeneous
+ultrarelativistic QED plasma are studied. It is shown that the sign of
+nonlinear turbulent Landau damping corresponds to an instability of the
+spacelike modes and, for sufficiently large turbulent fields, to an actual
+instability of a system.",1212.6555v1
+2013-02-26,Spin Mixing in Spinor Fermi Gases,"We study a spinor fermionic system under the effect of spin-exchange
+interaction. We focus on the interplay between the spin-exchange interaction
+and the effective quadratic Zeeman shift. We examine the static and the dynamic
+properties of both two- and many-body system. We find that the spin-exchange
+interaction induces coherent Rabi oscillation in the two-body system, but the
+oscillation is quickly damped when the system is extended to the many-body
+case.",1302.6549v1
+2013-03-12,Damped jump-telegraph processes,"We study a one-dimensional Markov modulated random walk with jumps. It is
+assumed that amplitudes of jumps as well as a chosen velocity regime are random
+and depend on a time spent by the process at a previous state of the underlying
+Markov process.
+  Equations for the distribution and equations for its moments are derived. We
+characterise the martingale distributions in terms of observable proportions
+between jump and velocity regimes.",1303.2796v1
+2013-05-19,On Collective Properties of Turbulent QED Plasma,"Polarization properties of turbulent stochastically inhomogeneous
+ultrarelativistic QED plasma are studied. It is shown that the sign of
+nonlinear turbulent Landau damping corresponds to an instability of the
+spacelike modes and, for sufficiently large turbulent fields, to an actual
+instability of a system. Modification of plasmon dispersion relations due to
+turbulent effects are studied.",1305.4414v1
+2013-06-17,Uniformly polynomially stable approximations for a class of second order evolution equations,"In this paper we study time semi-discrete approximations of a class of
+polynomially stable infinite dimensional systems modeling the damped
+vibrations. We prove that adding a suitable numerical viscosity term in the
+numerical scheme, one obtains approximations that are uniformly polynomially
+stable with respect to the discretization parameter.",1306.3807v1
+2013-08-21,Overstable Librations can account for the Paucity of Mean Motion Resonances among Exoplanet Pairs,"We assess the multi-planet systems discovered by the Kepler satellite in
+terms of current ideas about orbital migration and eccentricity damping due to
+planet-disk interactions. Our primary focus is on mean motion resonances. Only
+a few percent of planet pairs are in close proximity to a resonance. However,
+predicted migration rates (parameterized by $\tau_n=n/{|\dot n|}$) imply that
+during convergent migration most planets would have been captured into first
+order resonances. Eccentricity damping (parameterized by $\tau_e=e/{|\dot e|}$)
+offers a plausible resolution. Estimates suggest $\tau_e/\tau_n\sim (h/a)^2\sim
+10^{-2}$, where $h/a$ is the ratio of disk thickness to radius. Together,
+eccentricity damping and orbital migration give rise to an equilibrium
+eccentricity, $e_{eq}\sim(\tau_e/\tau_n)^{1/2}$. Capture is permanent provided
+$e_{eq}\lesssim \mu^{1/3}$, where $\mu$ denotes the planet to star mass ratio.
+But for $e_{eq}\gtrsim \mu^{1/3}$, capture is only temporary because librations
+around equilibrium are overstable and lead to passage through resonance on
+timescale $\tau_e$. Most Kepler planet pairs have $e_{eq}>\mu^{1/3}$. Since
+$\tau_n>> \tau_e$ is the timescale for migration between neighboring
+resonances, only a modest percentage of pairs end up trapped in resonances
+after the disk disappears. Planet pairs close to a mean motion resonance
+typically exhibit period ratios 1-2% larger than those for exact resonance. The
+direction of this shift undoubtedly reflects the same asymmetry that requires
+convergent migration for resonance capture. Permanent resonance capture at
+these separations from exact resonance would demand $\mu
+(\tau_n/\tau_e)^{1/2}\gtrsim 0.01$, a value that estimates of $\mu$ from
+transit data and $(\tau_e/\tau_n)^{1/2}$ from theory are insufficient to match.
+Plausible alternatives involve eccentricity damping during or after disk
+dispersal. (Abridged)",1308.4688v2
+2013-08-30,Nested Head-Tail Vlasov Solver,"Nested Head-Tail (NHT) is a Mathematica-based Vlasov solver for transverse
+oscillations in multi-bunch beams. It takes into account azimuthal, radial,
+coupled-bunch and beam-beam degrees of freedom, single- and inter-bunch dipole
+wakes, an arbitrary damper, beam-beam effects and Landau damping.",1309.0044v3
+2013-09-24,Attractors for damped quintic wave equations in bounded domains,"The dissipative wave equation with a critical quintic nonlinearity in smooth
+bounded three dimensional domain is considered. Based on the recent extension
+of the Strichartz estimates to the case of bounded domains, the existence of a
+compact global attractor for the solution semigroup of this equation is
+established. Moreover, the smoothness of the obtained attractor is also shown.",1309.6272v1
+2013-09-30,Harmonic oscillator: an analysis via Fourier series,"The Fourier series method is used to solve the homogeneous equation governing
+the motion of the harmonic oscillator. It is shown that the general solution to
+the problem can be found in a surprisingly simple way for the case of the
+simple harmonic oscillator. It is also shown that the damped harmonic
+oscillator is susceptible to the analysis.",1309.7918v1
+2013-10-01,"Observations and predictions at CesrTA, and outlook for ILC","In this paper, we will describe some of the recent experimental measurements
+[1, 2, 3] performed at CESRTA [4], and the supporting simulations, which probe
+the interaction of the electron cloud with the stored beam. These experiments
+have been done over a wide range of beam energies, emittances, bunch currents,
+and fill patterns, to gather sufficient information to be able to fully
+characterize the beam-electron-cloud interaction and validate the simulation
+programs. The range of beam conditions is chosen to be as close as possible to
+those of the ILC damping ring, so that the validated simulation programs can be
+used to predict the performance of these rings with regard to electroncloud-
+related phenomena. Using the new simulation code Synrad3D to simulate the
+synchrotron radiation environment, a vacuum chamber design has been developed
+for the ILC damping ring which achieves the required level of photoelectron
+suppression. To determine the expected electron cloud density in the ring, EC
+buildup simulations have been done based on the simulated radiation environment
+and on the expected performance of the ILC damping ring chamber mitigation
+prescriptions. The expected density has been compared with analytical estimates
+of the instability threshold, to verify that the ILC damping ring vacuum
+chamber design is adequate to suppress the electron cloud single-bunch
+head-tail instability.",1310.0261v1
+2013-10-21,A Critical History of Renormalization,"The history of renormalization is reviewed with a critical eye, starting with
+Lorentz's theory of radiation damping, through perturbative QED with Dyson,
+Gell-Mann & Low, and others, to Wilson's formulation and Polchinski's
+functional equation, and applications to ""triviality"", and dark energy in
+cosmology.",1310.5533v1
+2013-10-27,Fundamental limitations of half-metallicicity in spintronic materials,"Zero-point spin fluctuations are shown to strongly influence the ground state
+of ferromagnetic metals and to impose limitations for the fully spin polarized
+state assumed in half-metallic ferromagnets, which may influence their
+applications in spintronics. This phenomenon leads to the low-frequency Stoner
+excitations and cause strong damping and softening of magnons in
+magnetoresistive manganites observed experimentally.",1310.7174v1
+2013-12-13,Probing Intergalactic Neutral Hydrogen by the Lyman Alpha Red Damping Wing of Gamma-Ray Burst 130606A Afterglow Spectrum at z = 5.913,"The unprecedentedly bright optical afterglow of GRB 130606A located by Swift
+at a redshift close to the reionization era (z = 5.913) provides a new
+opportunity to probe the ionization status of intergalactic medium (IGM). Here
+we present an analysis of the red Ly alpha damping wing of the afterglow
+spectrum taken by Subaru/FOCAS during 10.4-13.2 hr after the burst. We find
+that the minimal model including only the baseline power-law and HI absorption
+in the host galaxy does not give a good fit, leaving residuals showing concave
+curvature in 8400-8900 A with an amplitude of about 0.6% of the flux. Such a
+curvature in the short wavelength range cannot be explained either by
+extinction at the host with standard extinction curves, intrinsic curvature of
+afterglow spectra, or by the known systematic uncertainties in the observed
+spectrum. The red damping wing by intervening HI gas outside the host can
+reduce the residual by about 3 sigma statistical significance. We find that a
+damped Ly alpha system is not favored as the origin of this intervening HI
+absorption, from the observed Ly beta and metal absorption features. Therefore
+absorption by diffuse IGM remains as a plausible explanation. A fit by a simple
+uniform IGM model requires HI neutral fraction of f_HI ~ 0.1-0.5 depending on
+the distance to the GRB host, implying high f_HI IGM associated with the
+observed dark Gunn-Peterson (GP) troughs. This gives a new evidence that the
+reionization is not yet complete at z ~ 6.",1312.3934v3
+2014-02-01,Effects of stellar flybys on planetary systems: 3D modeling of the circumstellar disks damping effects,"Stellar flybys in star clusters are suspected to affect the orbital
+architecture of planetary systems causing eccentricity excitation and orbital
+misalignment between the planet orbit and the equatorial plane of the star. We
+explore whether the impulsive changes in the orbital elements of planets,
+caused by an hyperbolic stellar flyby, can be fully damped by the circumstellar
+disk surrounding the star. The time required to disperse stellar clusters is in
+fact comparable to circumstellar disk's lifetime. We have modelled in 3D a
+system made of a solar type star surrounded by a low density disk with a giant
+planet embedded in it approached on a hyperbolic encounter trajectory by a
+second star, of similar mass and with its own disk. We focus on extreme
+configurations where a very deep stellar flyby perturbs a Jovian planet on an
+external orbit. This allows to test in full the ability of the disk to erase
+the effects of the stellar encounter. We find that the amount of mass lost by
+the disk during the stellar flyby is less than in 2D models where a single disk
+was considered due to the mass exchange between the two disks at the encounter.
+The damping in eccentricity is slightly faster than in 2D models and it occurs
+on timescales of the order of a few kyr. The only trace of the flyby left in
+the planet system, after about 10^4 yr, is a small misalignment, lower than 9
+degrees, between the star equatorial plane and the planet orbit. In a realistic
+model based on 3D simulations of star--planet--disk interactions, we find that
+stellar flybys cannot excite significant eccentricities and inclinations of
+planets in stellar clusters. The circumstellar disks hosting the planets damp
+on a short timescale all the step changes in the two orbital parameters
+produced during any stellar encounter. All records of past encounters are
+erased.",1402.0077v1
+2014-02-21,Damping of electron Zitterbewegung in carbon nanotubes,"Zitterbewegung (ZB, trembling motion) of electrons in semiconductor carbon
+nanotubes is described taking into account dephasing processes. The density
+matrix formalism is used for the theory. Differences between decay of ZB
+oscillations due to electron localization and that due to dephasing are
+discussed.",1402.5393v1
+2014-04-18,Exponential mixing for the white - forced damped nonlinear wave equation,"The paper is devoted to studying the stochastic nonlinear wave (NLW) equation
+in a bounded domain D $\subset$ R3. We show that the Markov process associated
+with the flow of solution has a unique stationary measure $\mu$, and the law of
+any solution converges to $\mu$ with exponential rate in the dual-Lipschitz
+norm",1404.4697v1
+2014-05-13,Magneto-seismological insights into the penumbral chromosphere and evidence for wave damping in spicules,"The observation of propagating magneto-hydrodynamic kink waves in magnetic
+structures and measurement of their properties (amplitude, phase speed) can be
+used to diagnose the plasma conditions in the neighbourhood of the magnetic
+structure via magneto-seismology (MS). We aim to reveal properties of the
+chromosphere/Transition Region above the sunspot penumbra using this technique.
+Hinode observed a sunspot as it was crossing the limb, providing a unique side
+on view of the sunspot atmosphere. The presence of large spicule-like jets is
+evident in \ion{Ca}{II} H images. The jets are found to support transverse wave
+motions that displace the central axis, which can be interpreted as a kink
+wave. The properties of a wave event are measured and used to determine the
+magnetic and density stratification along the structure. We also measure the
+width of the spicule and the intensity profile along the structure. The
+measured wave properties reveal an initial rapid increase in amplitude with
+height above the solar surface, followed by a decrease in amplitude. The MS
+inversion suggests this initial increase corresponds to large changes in
+density and magnetic field strength. In addition, we provide the first
+measurements of spicule width with height, which confirm that the spicule under
+goes rapid expansion. The measured expansion shows good agreement with the
+results from the MS. The observed variations in plasma parameters are suggested
+to be partly due to the presence of a gravitational stratified, ambient
+atmosphere. Combining width measurements with phase speed measurements implies
+the observed decrease in wave amplitude at greater heights can be explained by
+wave damping. Hence, we provide the first direct evidence of wave damping in
+chromospheric spicules and the quality factor of the damping is found to be
+significantly smaller than estimated coronal values.",1405.3203v1
+2014-05-27,Interior feedback stabilization of wave equations with dynamic boundary delay,"In this paper we consider an interior stabilization problem for the wave
+equation with dynamic boundary delay.We prove some stability results under the
+choice of damping operator. The proof of the main result is based on a
+frequency domain method and combines a contradiction argument with the
+multiplier technique to carry out a special analysis for the resolvent.",1405.6865v2
+2014-07-11,Remark on stabilization of second order evolution equations by unbounded dynamic feedbacks and applications,"In this paper we consider second order evolution equations with unbounded
+dynamic feedbacks. Under a regularity assumption we show that observability
+properties for the undamped problem imply decay estimates for the damped
+problem. We consider both uniform and non uniform decay properties.",1407.3070v1
+2014-09-11,Eliminating flutter for clamped von Karman plates immersed in subsonic flows,"We address the long-time behavior of a non-rotational von Karman plate in an
+inviscid potential flow. The model arises in aeroelasticity and models the
+interaction between a thin, nonlinear panel and a flow of gas in which it is
+immersed [6, 21, 23]. Recent results in [16, 18] show that the plate component
+of the dynamics (in the presence of a physical plate nonlinearity) converge to
+a global compact attracting set of finite dimension; these results were
+obtained in the absence of mechanical damping of any type. Here we show that,
+by incorporating mechanical damping the full flow-plate system, full
+trajectories---both plate and flow---converge strongly to (the set of)
+stationary states. Weak convergence results require ""minimal"" interior damping,
+and strong convergence of the dynamics are shown with sufficiently large
+damping. We require the existence of a ""good"" energy balance equation, which is
+only available when the flows are subsonic. Our proof is based on first showing
+the convergence properties for regular solutions, which in turn requires
+propagation of initial regularity on the infinite horizon. Then, we utilize the
+exponential decay of the difference of two plate trajectories to show that full
+flow-plate trajectories are uniform-in-time Hadamard continuous. This allows us
+to pass convergence properties of smooth initial data to finite energy type
+initial data. Physically, our results imply that flutter (a non-static end
+behavior) does not occur in subsonic dynamics. While such results were known
+for rotational (compact/regular) plate dynamics [14] (and references therein),
+the result presented herein is the first such result obtained for
+non-regularized---the most physically relevant---models.",1409.3308v5
+2014-12-15,Optomechanical laser cooling with mechanical modulations,"We theoretically study the laser cooling of cavity optomechanics when the
+mechanical resonance frequency and damping depend on time. In the regime of
+weak optomechanical coupling we extend the theory of laser cooling using an
+adiabatic approximation. We discuss the modifications of the cooling dynamics
+and compare it with numerical simulations in a wide range of modulation
+frequencies.",1412.4497v1
+2015-03-08,An Analytical Formulation of Power System Oscillation Frequency,"This letter proposes an analytical approach to formulate the power system
+oscillation frequency under a large disturbance. A fact is revealed that the
+oscillation frequency is only the function of the oscillation amplitude when
+the system's model and operating condition are fixed. Case studies also show
+that this function is damping-insensitive and could be applied to an inter-area
+model of a multi-machine power system.",1503.07554v1
+2015-04-07,Generation of coherent spin-wave modes in Yttrium Iron Garnet microdiscs by spin-orbit torque,"Spin-orbit effects [1-4] have the potential of radically changing the field
+of spintronics by allowing transfer of spin angular momentum to a whole new
+class of materials. In a seminal letter to Nature [5], Kajiwara et al. showed
+that by depositing Platinum (Pt, a normal metal) on top of a 1.3 $\mu$m thick
+Yttrium Iron Garnet (YIG, a magnetic insulator), one could effectively transfer
+spin angular momentum through the interface between these two different
+materials. The outstanding feature was the detection of auto-oscillation of the
+YIG when enough dc current was passed in the Pt. This finding has created a
+great excitement in the community for two reasons: first, one could control
+electronically the damping of insulators, which can offer improved properties
+compared to metals, and here YIG has the lowest damping known in nature;
+second, the damping compensation could be achieved on very large objects, a
+particularly relevant point for the field of magnonics [6,7] whose aim is to
+use spin-waves as carriers of information. However, the degree of coherence of
+the observed auto-oscillations has not been addressed in ref. [5]. In this
+work, we emphasize the key role of quasi-degenerate spin-wave modes, which
+increase the threshold current. This requires to reduce both the thickness and
+lateral size in order to reach full damping compensation [8] , and we show
+clear evidence of coherent spin-orbit torque induced auto-oscillation in
+micron-sized YIG discs of thickness 20 nm.",1504.01512v1
+2015-05-01,Periodic solutions for nonlinear hyperbolic evolution systems,"We shall deal with the periodic problem for nonlinear perturbations of
+abstract hyperbolic evolution equations generating an evolution system of
+contractions. We prove an averaging principle for the translation along
+trajectories operator associated to the nonlinear evolution system, expressed
+in terms of the topological degree. The abstract results shall be applied to
+the damped hyperbolic partial differential equation.",1505.00150v1
+2015-05-28,"Moore-Gibson-Thompson equation with memory, part I: exponential decay of energy","We are interested in the Moore-Gibson-Thompson(MGT) equation with memory
+\begin{equation}\nonumber \tau u_{ttt}+ \alpha u_{tt}+c^2\A u+b\A u_t
+-\int_0^tg(t-s)\A w(s)ds=0. \end{equation} We first classify the memory into
+three types. Then we study how a memory term creates damping mechanism and how
+the memory causes energy decay.",1505.07523v1
+2015-05-29,Fission barriers heights in A$\sim$ 200 mass region,"Statistical model analysis has been carried out for $p$ and $\alpha$ induced
+fission reactions using a consistent description for fission barrier and level
+density in A $\sim$ 200 mass region. A continuous damping of shell correction
+with excitation energy have been considered. Extracted fission barriers agree
+well with the recent microscopic-macroscopic model. The shell corrections at
+the saddle point were found to be not significant.",1505.08026v1
+2015-06-16,Revisit on How to Derive Asymptotic Profiles to Some Evolution Equations,"We consider the Cauchy problem in ${\bf R}^{n}$ for heat and damped wave
+equations. We derive asymptotic profiles to those solutions with weighted
+$L^{1,1}({\bf R}^{n})$ data by presenting a simple method.",1506.04858v1
+2015-06-21,Predicting the Influence of Plate Geometry on the Eddy Current Pendulum,"We quantitatively analyze a familiar classroom demonstration, Van
+Waltenhofen's eddy current pendulum, to predict the damping effect for a
+variety of plate geometries from first principles. Results from conformal
+mapping, finite element simulations and a simplified model suitable for
+introductory classes are compared with experiments.",1506.06401v1
+2015-07-19,"Alfvén wave phase-mixing in flows: Why over-dense, solar coronal, open magnetic field structures are cool?","The motivation for this study is to include the effect of plasma flow in
+Alfv\'en wave (AW) damping via phase mixing and to explore the observational
+implications. Our magnetohydrodynamic (MHD) simulations and analytical
+calculations show that, when a background flow is present, mathematical
+expressions for the AW damping via phase mixing are modified by the following
+substitution: $C_A^\prime(x) \to C_A^\prime(x)+V_0^\prime(x)$, where $C_A$ and
+$V_0$ are AW phase and the flow speeds, and the prime denotes a derivative in
+the direction across the background magnetic field. In uniform magnetic fields
+and over-dense plasma structures, where $C_A$ is smaller than in the
+surrounding plasma, the flow, which is confined to the structure and going in
+the same direction as the AW, reduces the effect of phase-mixing, because on
+the edges of the structure $C_A^\prime$ and $V_0^\prime$ have opposite signs.
+Thus, the wave damps by means of slower phase-mixing compared to the case
+without the flow. This is the result of the co-directional flow that reduces
+the wave front stretching in the transverse direction. We apply our findings to
+addressing the question why over-dense solar coronal open magnetic field
+structures (OMFS) are cooler than the background plasma. Observations show that
+the over-dense OMFS (e.g. solar coronal polar plumes) are cooler than
+surrounding plasma and that, in these structures, Doppler line-broadening is
+consistent with bulk plasma motions, such as AW. If over-dense solar coronal
+OMFS are heated by AW damping via phase-mixing, we show that, co-directional
+with AW, plasma flow in them reduces the phase-mixing induced-heating, thus
+providing an explanation of why they appear cooler than the background.",1507.05293v2
+2015-09-28,Linear inviscid damping for a class of monotone shear flow in Sobolev spaces,"In this paper, we prove the decay estimates of the velocity and $H^1$
+scattering for the 2D linearized Euler equations around a class of monotone
+shear flow in a finite channel. Our result is consistent with the decay rate
+predicted by Case in 1960.",1509.08228v1
+2015-10-09,Energy Dissipation and Landau Damping in Two- and Three-Dimensional Plasma Turbulence,"Plasma turbulence is ubiquitous in space and astrophysical plasmas, playing
+an important role in plasma energization, but the physical mechanisms leading
+to dissipation of the turbulent energy remain to be definitively identified.
+Kinetic simulations in two dimensions (2D) have been extensively used to study
+the dissipation process. How the limitation to 2D affects energy dissipation
+remains unclear. This work provides a model of comparison between two- and
+three-dimensional (3D) plasma turbulence using gyrokinetic simulations; it also
+explores the dynamics of distribution functions during the dissipation process.
+It is found that both 2D and 3D nonlinear gyrokinetic simulations of a low-beta
+plasma generate electron velocity-space structures with the same
+characteristics as that of linear Landau damping of Alfv\'en waves in a 3D
+linear simulation. The continual occurrence of the velocity-space structures
+throughout the turbulence simulations suggests that the action of Landau
+damping may be responsible for the turbulent energy transfer to electrons in
+both 2D and 3D, and makes possible the subsequent irreversible heating of the
+plasma through collisional smoothing of the velocity-space fluctuations.
+Although, in the 2D case where variation along the equilibrium magnetic field
+is absent, it may be expected that Landau damping is not possible, a common
+trigonometric factor appears in the 2D resonant denominator, leaving the
+resonance condition unchanged from the 3D case. The evolution of the 2D and 3D
+cases is qualitatively similar. However, quantitatively the nonlinear energy
+cascade and subsequent dissipation is significantly slower in the 2D case.",1510.02842v2
+2015-11-12,Global weak solutions to 3D compressible Navier-Stokes-Poisson equations with density-dependent viscosity,"Global-in-time weak solutions to the Compressible Navier-Stokes-Poisson
+equations in a three-dimensional torus for large data are considered in this
+paper. The system takes into account density-dependent viscosity and
+non-monotone presseur. We prove the existence of global weak solutions to NSP
+equations with damping term by using the Faedo-Galerkin method and the
+compactness arguments on the condition that the adiabatic constant satisfies
+$\gamma>\frac{4}{3}$.",1511.03841v1
+2015-11-18,Temperature cooling in quantum dissipation channel and the correspondimg thermal vacuum state,"We examine temperature cooling of optical chaotic light in a quantum
+dissipation channel with the damping parameter k.The way we do it is by
+introducing its thermal vacuum state which can expose entangling effect between
+the system and the reservoir. The temperature cooling formula is derived, which
+depends on the parameter k, by adjusting k one can control temperature.",1511.05777v1
+2015-12-03,Lieb-Thirring inequalities on the torus,"We consider the Lieb-Thirring inequalities on the d-dimensional torus with
+arbitrary periods. In the space of functions with zero average with respect to
+the shortest coordinate we prove the Lieb-Thirring inequalities for the
+$\gamma$-moments of the negative eigenvalues with constants independent of
+ratio of the periods. Applications to the attractors of the damped
+Navier-Stokes system are given.",1512.01160v1
+2016-01-30,Quantum Dynamics of Complex Hamiltonians,"Non hermitian Hamiltonians play an important role in the study of dissipative
+quantum systems. We show that using states with time dependent normalization
+can simplify the description of such systems especially in the context of the
+classical limit. We apply this prescription to study the damped harmonic
+oscillator system. This is then used to study the problem of radiation in leaky
+cavity.",1602.00157v2
+2016-02-17,Instability of a witness bunch in a plasma bubble,"The stability of a trailing witness bunch, accelerated by a plasma wake
+accelerator (PWA) in a blow-out regime, is discussed. The instability growth
+rate as well as the energy spread, required for BNS damping, are obtained. A
+relationship between the PWA power efficiency and the BNS energy spread is
+derived.",1602.05260v2
+2016-02-25,Strong Ly alpha Emission in the Proximate Damped Ly alpha Absorption Trough toward the Quasar SDSS J095253.83+011422.0,"SDSS J095253.83+011422.0 (SDSS J0952+0114) was reported by Hall et al. (2004)
+as an exotic quasar at $z_{\rm em}=3.020$. In contrast to prominent broad
+metal--line emissions with FWHM~9000 km/s, only a narrow Ly \alpha emission
+line is present with FWHM~1000 km/s. The absence of broad Ly alpha emission
+line has been a mystery for more than a decade. In this paper, we demonstrate
+that this is due to dark Proximate Damped Ly alpha Absorption (PDLA) at $z_{\rm
+abs}=3.010$ by identifying associated Lyman absorption line series from the
+damped Ly beta up to Ly9, as well as the Lyman limit absorption edge. The PDLA
+cloud has a column density of $\log N_{\rm H\,I}({\rm cm}^{-2})=21.8\pm0.2$, a
+metallicity of [Zn/H]$>-1.0$, and a spatial extent exceeding the Narrow
+Emission Line Region (NELR) of the quasar. With a luminosity of $L_{{\rm
+Ly}\alpha}\sim10^{45}$ erg s$^{-1}$, the residual Ly alpha emission superposed
+on the PDLA trough is of two orders of magnitude stronger than previous
+reports. This is best explained as re-radiated photons arising from the quasar
+outflowing gas at a scale larger than the NELR. The PDLA here, acting like a
+natural coronagraph, provides us with a good insight into the illuminated gas
+in the vicinity of the quasar, which are usually hard to resolve due to their
+small size and ""seeing fuzz"" of bright quasars. Notably, SDSS J0952+0114
+analogs might be easily omitted in the spectroscopic surveys of DLAs and PDLAs,
+as their damped Ly alpha troughs can be fully filled by additional strong Ly
+alpha emissions. Our preliminary survey shows that such systems are not very
+rare. They are potentially a unique sample for probing strong quasar feedback
+phenomena in the early universe.",1602.07880v2
+2016-03-27,Evolution of One-Dimensional Wind-Driven Sea Spectra,"We analyze modern operational models of wind wave prediction on the subject
+for compliance dissipation. Our numerical simulations from the ""first
+principle"" demonstrate that heuristic formulas for damping rate of free wind
+sea due to ""white capping"" (or wave breaking) dramatically exaggerates the role
+of this effect in these models.",1603.08229v1
+2016-03-07,Faddeev-Jackiw Quantization of Non-Autonomous Singular Systems,"We extend the quantization \`a la Faddeev-Jackiw for non-autonomous singular
+systems. This leads to a generalization of the Schr\""odinger equation for those
+systems. The method is exemplified by the quantization of the damped harmonic
+oscillator and the relativistic particle in an external electromagnetic field.",1603.08407v1
+2016-05-06,Existence of invariant measures for the stochastic damped Schrödinger equation,"In this paper, we address the long time behaviour of solutions of the
+stochastic Schrodinger equation in $\mathbb{R}^d$. We prove the existence of an
+invariant measure and establish asymptotic compactness of solutions, implying
+in particular the existence of an ergodic measure.",1605.02014v1
+2016-05-25,"Dynamic analysis of simultaneous adaptation of force, impedance and trajectory","When carrying out tasks in contact with the environment, humans are found to
+concurrently adapt force, impedance and trajectory. Here we develop a robotic
+model of this mechanism in humans and analyse the underlying dynamics. We
+derive a general adaptive controller for the interaction of a robot with an
+environment solely characterised by its stiffness and damping, using Lyapunov
+theory.",1605.07834v1
+2016-06-24,Mixing for the Burgers equation driven by a localised two-dimensional stochastic forcing,"We consider the one-dimensional Burgers equation perturbed by a stochastic
+forcing, which is assumed to be white in time and localised and low-dimensional
+in space. We establish a mixing property for the Markov process associated with
+the problem in question. The proof is based on a general criterion for mixing
+and a recent result on global approximate controllability to trajectories for
+damped conservation laws.",1606.07763v1
+2016-07-01,Randomized block proximal damped Newton method for composite self-concordant minimization,"In this paper we consider the composite self-concordant (CSC) minimization
+problem, which minimizes the sum of a self-concordant function $f$ and a
+(possibly nonsmooth) proper closed convex function $g$. The CSC minimization is
+the cornerstone of the path-following interior point methods for solving a
+broad class of convex optimization problems. It has also found numerous
+applications in machine learning. The proximal damped Newton (PDN) methods have
+been well studied in the literature for solving this problem that enjoy a nice
+iteration complexity. Given that at each iteration these methods typically
+require evaluating or accessing the Hessian of $f$ and also need to solve a
+proximal Newton subproblem, the cost per iteration can be prohibitively high
+when applied to large-scale problems. Inspired by the recent success of block
+coordinate descent methods, we propose a randomized block proximal damped
+Newton (RBPDN) method for solving the CSC minimization. Compared to the PDN
+methods, the computational cost per iteration of RBPDN is usually significantly
+lower. The computational experiment on a class of regularized logistic
+regression problems demonstrate that RBPDN is indeed promising in solving
+large-scale CSC minimization problems. The convergence of RBPDN is also
+analyzed in the paper. In particular, we show that RBPDN is globally convergent
+when $g$ is Lipschitz continuous. It is also shown that RBPDN enjoys a local
+linear convergence. Moreover, we show that for a class of $g$ including the
+case where $g$ is Lipschitz differentiable, RBPDN enjoys a global linear
+convergence. As a striking consequence, it shows that the classical damped
+Newton methods [22,40] and the PDN [31] for such $g$ are globally linearly
+convergent, which was previously unknown in the literature. Moreover, this
+result can be used to sharpen the existing iteration complexity of these
+methods.",1607.00101v1
+2016-11-09,Witnessing quantum capacities of correlated channels,"We test a general method to detect lower bounds of the quantum channel
+capacity for two-qubit correlated channels. We consider in particular
+correlated dephasing, depolarising and amplitude damping channels. We show that
+the method is easily implementable, it does not require a priori knowledge
+about the channels, and it is very efficient, since it does not rely on full
+quantum process tomography.",1611.02857v1
+2017-03-20,Recovery of the starting times of delayed signals,"We present a new method to locate the starting points in time of an arbitrary
+number of (damped) delayed signals. For a finite data sequence, the method
+permits to first locate the starting point of the component with the longest
+delay, and then --by iteration-- all the preceding ones. Numerical examples are
+given and noise sensitivity is tested for weak noise.",1703.07001v1
+2017-05-13,Eigenvalues of one-dimensional non-self-adjoint Dirac operators and applications,"We analyze eigenvalues emerging from thresholds of the essential spectrum of
+one-dimensional Dirac operators perturbed by complex and non-symmetric
+potentials. In the general non-self-adjoint setting we establish the existence
+and asymptotics of weakly coupled eigenvalues and Lieb-Thirring inequalities.
+As physical applications we investigate the damped wave equation and armchair
+graphene nanoribbons.",1705.04833v1
+2017-09-07,"The driven oscillator, with friction","This paper develops further the semi-classical theory of an harmonic
+oscillator acted on by a Gaussian white noise force discussed in
+(arXiv:1508.02379). Here I add to that theory the effects of Brownian damping
+(friction). Albeit semi-classical, the theory can be used to model quantum
+expectations and probabilities. I consider several examples.",1709.03391v1
+2017-11-16,Correlations in the three-dimensional Lyman-alpha forest contaminated by high column density absorbers,"Correlations measured in three dimensions in the Lyman-alpha forest are
+contaminated by the presence of the damping wings of high column density (HCD)
+absorbing systems of neutral hydrogen (HI; having column densities
+$N(\mathrm{HI}) > 1.6\times10^{17}\,\mathrm{atoms}\,\mathrm{cm}^{-2}$), which
+extend significantly beyond the redshift-space location of the absorber. We
+measure this effect as a function of the column density of the HCD absorbers
+and redshift by measuring 3D flux power spectra in cosmological hydrodynamical
+simulations from the Illustris project. Survey pipelines exclude regions
+containing the largest damping wings. We find that, even after this procedure,
+there is a scale-dependent correction to the 3D Lyman-alpha forest flux power
+spectrum from residual contamination. We model this residual using a simple
+physical model of the HCD absorbers as linearly biased tracers of the matter
+density distribution, convolved with their Voigt profiles and integrated over
+the column density distribution function. We recommend the use of this model
+over existing models used in data analysis, which approximate the damping wings
+as top-hats and so miss shape information in the extended wings. The simple
+'linear Voigt model' is statistically consistent with our simulation results
+for a mock residual contamination up to small scales ($|k| <
+1\,h\,\mathrm{Mpc}^{-1}$). It does not account for the effect of the highest
+column density absorbers on the smallest scales (e.g., $|k| >
+0.4\,h\,\mathrm{Mpc}^{-1}$ for small damped Lyman-alpha absorbers; HCD
+absorbers with $N(\mathrm{HI}) \sim
+10^{21}\,\mathrm{atoms}\,\mathrm{cm}^{-2}$). However, these systems are in any
+case preferentially removed from survey data. Our model is appropriate for an
+accurate analysis of the baryon acoustic oscillations feature. It is
+additionally essential for reconstructing the full shape of the 3D flux power
+spectrum.",1711.06275v2
+2017-12-08,An algorithm to resolve γ-rays from charged cosmic rays with DAMPE,"The DArk Matter Particle Explorer (DAMPE), also known as Wukong in China,
+launched on December 17, 2015, is a new high energy cosmic ray and {\gamma}-ray
+satellite-borne observatory in space. One of the main scientific goals of DAMPE
+is to observe GeV-TeV high energy {\gamma}-rays with accurate energy, angular,
+and time resolution, to indirectly search for dark matter particles and for the
+study of high energy astrophysics. Due to the comparatively higher fluxes of
+charged cosmic rays with respect to {\gamma}-rays, it is challenging to
+identify {\gamma}-rays with sufficiently high efficiency minimizing the amount
+of charged cosmic ray contamination. In this work we present a method to
+identify {\gamma}-rays in DAMPE data based on Monte Carlo simulations, using
+the powerful electromagnetic/hadronic shower discrimination provided by the
+calorimeter and the veto detection of charged particles provided by the plastic
+scintillation detector. Monte Carlo simulations show that after this selection
+the number of electrons and protons that contaminate the selected {\gamma}-ray
+events at $\sim10$ GeV amounts to less than 1% of the selected sample. Finally,
+we use flight data to verify the effectiveness of the method by highlighting
+known {\gamma}-ray sources in the sky and by reconstructing preliminary light
+curves of the Geminga pulsar.",1712.02939v1
+2017-12-27,A simple and natural interpretations of the DAMPE cosmic-ray electron/positron spectrum within two sigma deviations,"The DArk Matter Particle Explorer (DAMPE) experiment has recently announced
+the first results for the measurement of total electron plus positron fluxes
+between 25 GeV and 4.6 TeV. A spectral break at about 0.9 TeV and a tentative
+peak excess around 1.4 TeV have been found. However, it is very difficult to
+reproduce both the peak signal and the smooth background including spectral
+break simultaneously. We point out that the numbers of events in the two energy
+ranges (bins) close to the 1.4 TeV excess have $1\sigma$ deficits. With the
+basic physics principles such as simplicity and naturalness, we consider the
+$-2\sigma$, $+2\sigma$, and $-1\sigma$ deviations due to statistical
+fluctuations for the 1229.3~GeV bin, 1411.4~GeV bin, and 1620.5~GeV bin.
+Interestingly, we show that all the DAMPE data can be explained consistently
+via both the continuous distributed pulsar and dark matter interpretations,
+which have $\chi^{2} \simeq 17.2 $ and $\chi^{2} \simeq 13.9$ (for all the 38
+points in DAMPE electron/positron spectrum with 3 of them revised),
+respectively. These results are different from the previous analyses by
+neglecting the 1.4 TeV excess. At the same time, we do a similar global fitting
+on the newly released CALET lepton data, which could also be interpreted by
+such configurations. Moreover, we present a $U(1)_D$ dark matter model with
+Breit-Wigner mechanism, which can provide the proper dark matter annihilation
+cross section and escape the CMB constraint. Furthermore, we suggest a few ways
+to test our proposal.",1712.09586v6
+2018-03-21,Well-posedness and stabilization of the Benjamin-Bona-Mahony equation on star-shaped networks,"We study the stabilization issue of the Benjamin-Bona-Mahony (BBM) equation
+on a finite star-shaped network with a damping term acting on the central node.
+In a first time, we prove the well-posedness of this system. Then thanks to the
+frequency domain method, we get the asymptotic stabilization result.",1803.07914v1
+2018-04-05,Finite time blow up for wave equations with strong damping in an exterior domain,"We consider the initial boundary value problem in exterior domain for
+semilinear wave equations with power-type nonlinearity |u| p. We will establish
+blow-up results when p is less than or equal to Strauss' exponent which is the
+same one for the whole space case R n .",1804.01689v1
+2018-04-13,Well-posedness and long time behavior of singular Langevin stochastic differential equations,"In this paper, we study damped Langevin stochastic differential equations
+with singular velocity fields. We prove the strong well-posedness of such
+equations. Moreover, by combining the technique of Lyapunov functions with
+Krylov's estimate, we also establish the exponential ergodicity for the unique
+strong solution.",1804.05086v2
+2018-04-27,Contribution of phase-mixing of Alfvén waves to coronal heating in multi-harmonic loop oscillations,"Kink oscillations of a coronal loop are observed and studied in detail
+because they provide a unique probe into the structure of coronal loops through
+MHD seismology and a potential test of coronal heating through the phase-mixing
+of Alfv\'en waves. In particular, recent observations show that standing
+oscillations of loops often involve also higher harmonics, beside the
+fundamental mode. The damping of these kink oscillations is explained by mode
+coupling with Alfv\'en waves. We investigate the consequences for wave-based
+coronal heating of higher harmonics and what coronal heating observational
+signatures we may use to infer the presence of higher harmonic kink
+oscillations. We perform a set of non-ideal MHD simulations where the damping
+of the kink oscillation of a flux tube via mode coupling is modelled. Our MHD
+simulation parameters are based on the seismological inversion of an
+observation for which the first three harmonics are detected. We study the
+phase-mixing of Alfv\'en waves that leads to the deposition of heat in the
+system, and we apply the seismological inversion techniques to the MHD
+simulation output. We find that the heating due to phase-mixing of the Alfv\'en
+waves triggered by the damping of the kink oscillation is relatively small,
+however we can illustrate i) how the heating location drifts due to the
+subsequent damping of lower order harmonics. We also address the role of the
+higher order harmonics and the width of the boundary shell in the energy
+deposition. We conclude that the coronal heating due to phase-mixing seems not
+to provide enough energy to maintain the thermal structure of the solar corona
+even when multi-harmonics oscillations are included, and these oscillations
+play an inhibiting role in the development of smaller scale structures.",1804.10562v1
+2018-05-23,Effect of time varying transmission rates on coupled dynamics of epidemic and awareness over multiplex network,"In the present work, a non-linear stochastic model is presented to study the
+effect of time variation of transmission rates on the co-evolution of epidemics
+and its corresponding awareness over a two layered multiplex network. In this
+model, the infection transmission rate of a given node in the epidemic layer
+depends upon its awareness probability in the awareness layer. Similarly, the
+infection information transmission rate of a node in the awareness layer
+depends upon its infection probability in the epidemic layer. The spread of
+disease resulting from physical contacts is described in terms of SIS
+(Susceptible Infected Susceptible) process over the epidemic layer and the
+spread of information about the disease outbreak is described in terms of UAU
+(Unaware Aware Unaware) process over the virtual interaction mediated awareness
+layer. The time variation of the transmission rates and the resulting
+co-evolution of these mutually competing processes is studied in terms of a
+network topology depend parameter({\alpha}). Using a second order linear theory
+it has been shown that in the continuous time limit, the co-evolution of these
+processes can be described in terms of damped and driven harmonic oscillator
+equations. From the results of the Monte-Carlo simulation, it is shown that for
+the suitable choice of parameter({\alpha}), the two process can either exhibit
+sustained oscillatory or damped dynamics. The damped dynamics corresponds to
+the endemic state. Further, for the case of endemic state it is shown that the
+inclusion of awareness layer significantly lowers the disease transmission rate
+and reduces the size of epidemic. The endemic state infection probability of a
+given node corresponding to the damped dynamics is found to have dependence
+upon both the transmission rates as well as on both absolute intra-layer and
+relative inter-layer degree of the individual nodes.",1805.08947v2
+2018-06-09,Recovery Analysis of Damped Spectrally Sparse Signals and Its Relation to MUSIC,"One of the classical approaches for estimating the frequencies and damping
+factors in a spectrally sparse signal is the MUSIC algorithm, which exploits
+the low-rank structure of an autocorrelation matrix. Low-rank matrices have
+also received considerable attention recently in the context of optimization
+algorithms with partial observations, and nuclear norm minimization (NNM) has
+been widely used as a popular heuristic of rank minimization for low-rank
+matrix recovery problems. On the other hand, it has been shown that NNM can be
+viewed as a special case of atomic norm minimization (ANM), which has achieved
+great success in solving line spectrum estimation problems. However, as far as
+we know, the general ANM (not NNM) considered in many existing works can only
+handle frequency estimation in undamped sinusoids. In this work, we aim to fill
+this gap and deal with damped spectrally sparse signal recovery problems. In
+particular, inspired by the dual analysis used in ANM, we offer a novel
+optimization-based perspective on the classical MUSIC algorithm and propose an
+algorithm for spectral estimation that involves searching for the peaks of the
+dual polynomial corresponding to a certain NNM problem, and we show that this
+algorithm is in fact equivalent to MUSIC itself. Building on this connection,
+we also extend the classical MUSIC algorithm to the missing data case. We
+provide exact recovery guarantees for our proposed algorithms and quantify how
+the sample complexity depends on the true spectral parameters. In particular,
+we provide a parameter-specific recovery bound for low-rank matrix recovery of
+jointly sparse signals rather than use certain incoherence properties as in
+existing literature. Simulation results also indicate that the proposed
+algorithms significantly outperform some relevant existing methods (e.g., ANM)
+in frequency estimation of damped exponentials.",1806.03511v5
+2018-07-13,N-body simulations of structure formation in thermal inflation cosmologies,"Thermal inflation models (which feature two inflationary stages) can display
+damped primordial curvature power spectra on small scales which generate damped
+matter fluctuations. For a reasonable choice of parameters, thermal inflation
+models naturally predict a suppression of the matter power spectrum on galactic
+and sub-galactic scales, mimicking the effect of warm or interacting dark
+matter. Matter power spectra in these models are also characterised by an
+excess of power (w.r.t. the standard $\Lambda$CDM power spectrum) just below
+the suppression scale. By running a suite of N-body simulations we investigate
+the non-linear growth of structure in models of thermal inflation. We measure
+the non-linear matter power spectrum and extract halo statistics, such as the
+halo mass function, and compare these quantities with those predicted in the
+standard $\Lambda$CDM model and in other models with damped matter
+fluctuations. We find that the thermal inflation models considered here produce
+measurable differences in the matter power spectrum from $\Lambda$CDM at
+redshifts $z>5$, while the halo mass functions are appreciably different at all
+redshifts. The halo mass function at $z=0$ for thermal inflation displays an
+enhancement of around $\sim 20\%$ w.r.t. $\Lambda$CDM and a damping at lower
+halo masses, with the position of the enhancement depending on the value of the
+free parameter in the model. The enhancement in the halo mass function (w.r.t.
+$\Lambda$CDM ) increases with redshift, reaching $\sim 40\%$ at $z=5$. We also
+study the accuracy of the analytical Press-Schechter approach, using different
+filters to smooth the density field, to predict halo statistics for thermal
+inflation. We find that the predictions with the smooth-$k$ filter agree with
+the simulation results over a wider range of halo masses than is the case with
+other filters commonly used in the literature.",1807.04980v2
+2018-07-16,Global existence for semilinear damped wave equations in relation with the Strauss conjecture,"We study the global existence of solutions to semilinear wave equations with
+power-type nonlinearity and general lower order terms on $n$ dimensional
+nontrapping asymptotically Euclidean manifolds, when $n=3, 4$. In addition, we
+prove almost global existence with sharp lower bound of the lifespan for the
+four dimensional critical problem.",1807.05908v1
+2018-07-20,Effect of correlated noise channels on quantum speed limit,"We study the effect of correlated Markovian noise channels on the quantum
+speed limit of an open system. This is done for correlated dephasing and
+amplitude damping channels for a two qubit atomic model. Our model serves as a
+platform for a detailed study of speed of quantum evolution in correlated open
+systems.",1807.07782v2
+2018-08-20,Local existence of Strong solutions for a fluid-structure interaction model,"We are interested in studying a system coupling the compressible
+Navier-Stokes equations with an elastic structure located at the boundary of
+the fluid domain. Initially the fluid domain is rectangular and the beam is
+located on the upper side of the rectangle. The elastic structure is modeled by
+an Euler-Bernoulli damped beam equation. We prove the local in time existence
+of strong solutions for that coupled system.",1808.06716v1
+2018-09-04,Creation of bipartite steering correlations by a fast damped auxiliary mode,"We consider a three-mode system and show how steering correlations can be
+created between two modes of the system using the fast dissipation of the third
+mode. These correlations result in a directional form of entanglement, called
+quantum or EPR steering. We illustrate this on examples of the interactions
+among damped radiation modes in an optomechanical three-mode system. By
+assuming that one of the modes undergoes fast dissipation, we show that the
+coupling of that mode to one or two other modes of the system may result in
+one- or two-way quantum steering. Explicit analytical results are given for the
+steering parameters. We find that two modes coupled by the parametric-type
+interaction and damped with the same rates can be entangled but cannot exhibit
+quantum steering. When, in addition, one of the modes is coupled to a fast
+damped mode, steering correlations are created and the modes then exhibit
+one-way steering. The creation of the steering correlations is interpreted in
+the context of the variances of the quadrature components of the modes that the
+steering correlations result from an asymmetry in the variances of the
+quadrature components of the modes induced by the auxiliary mode. It is found
+that the fluctuations act directionally that quantum steering may occur only
+when the variance of the steering mode is larger that the variance of the
+steered mode. The scheme is shown to be quite robust against the thermal
+excitation of the modes if the fluctuations of the steering mode are larger
+than the fluctuations of the steered mode.",1809.01176v1
+2018-10-06,Global Well-Posedness and Global Attractor for Two-dimensional Zakharov-Kuznetsov Equation,"The initial value problem for two-dimensional Zakharov-Kuznetsov equation is
+shown to be globally well-posed in $H^s({\mathbb{R}^2})$ for all
+$\frac{5}{7}<s<1$ via using $I$-method in the context of atomic spaces. By
+means of the increment of modified energy, the exsitence of global attractor
+for weakly damped, forced Zakharov-Kuznetsov equation is also established in
+$H^s({\mathbb{R}^2})$ for $\frac{10}{11}<s<1$.",1810.02984v1
+2018-10-07,Uniform attractors for measure-driven quintic wave equation with periodic boundary conditions,"We give a detailed study of attractors for measure driven quintic damped wave
+equations with periodic boundary conditions. This includes uniform
+energy-to-Strichartz estimates, the existence of uniform attractors in a weak
+or strong topology in the energy phase space, the possibility to present them
+as a union of all complete trajectories, further regularity, etc.",1810.03149v1
+2018-10-13,Exponential Decay in a Timoshenko-type System of Thermoelasticity of Type III with Frictional versus Viscoelatic Damping and Delay,"In this work, a Timoshenko system of type III of thermoelasticity with
+frictional versus viscoelastic under Dirichlet-Dirichlet-Neumann boundary
+conditions was considered. By exploiting energy method to produce a suitable
+Lyapunov functional, we establish the global existence, exponential decay of
+Type-III case.",1810.05820v1
+2018-12-22,Damping of acoustic waves in straight ducts and turbulent flow conditions,"In this paper the propagation of acoustic plane waves in turbulent, fully
+developed flow is studied by means of an experimental investigation carried out
+in a straight, smooth-walled duct.The presence of a coherent perturbation, such
+as an acoustic wave in a turbulent confined flow, generates the oscillation of
+the wall shear stress. In this circumstance a shear wave is excited and
+superimposed on the sound wave. The turbulent shear stress is modulated by the
+shear wave and the wall shear stress is strongly affected by the turbulence.
+From the experimental point of view, it results in a measured damping strictly
+connected to the ratio between the thickness of the acoustic sublayer, which is
+frequency dependent, and the thickness of the viscous sublayer of the turbulent
+mean flow, the last one being dependent on the Mach number. By reducing the
+turbulence, the viscous sublayer thickness increases and the wave propagation
+is mainly dominated by convective effects. In the present work, the damping and
+wall impedance have been extracted from the measured complex wavenumber, which
+represents the most important parameter used to characterize the wave
+propagation. An experimental approach, referred to as iterative plane wave
+decomposition, has been used in order to obtain the results. The investigations
+have been carried out at low Mach number turbulent flows, low Helmholtz numbers
+and low shear wavenumbers. The aim is to overcome a certain lack of
+experimental results found by the authors of the most recent models for the
+plane wave propagation in turbulent flows, such as Knutsson et al. (The effect
+of turbulence damping on acoustic wave propagation in tubes, Journal of Sound
+and Vibration, Vol. 329, No. 22, 2010), and Weng et al. (The attenuation of
+sound by turbulence in internal flows, The Journal of the Acoustical Society of
+America 133(6), 2013).",1812.11063v1
+2019-01-30,Transverse waves in coronal flux tubes with thick boundaries: The effect of longitudinal flows,"Observations show that transverse magnetohydrodynamic (MHD) waves and flows
+are often simultaneously present in magnetic loops of the solar corona. The
+waves are resonantly damped in the Alfv\'en continuum because of plasma and/or
+magnetic field nonuniformity across the loop. The resonant damping is relevant
+in the context of coronal heating, since it provides a mechanism to cascade
+energy down to the dissipative scales. It has been theoretically shown that the
+presence of flow affects the waves propagation and damping, but most of the
+studies rely on the unjustified assumption that the transverse nonuniformity is
+confined to a boundary layer much thinner than the radius of the loop. Here we
+present a semi-analytic technique to explore the effect of flow on resonant MHD
+waves in coronal flux tubes with thick nonuniform boundaries. We extend a
+published method, which was originally developed for a static plasma, in order
+to incorporate the effect of flow. We allowed the flow velocity to continuously
+vary within the nonuniform boundary from the internal velocity to the external
+velocity. The analytic part of the method is based on expressing the wave
+perturbations in the thick nonuniform boundary of the loop as a Frobenius
+series that contains a singular term accounting for the Alfv\'en resonance,
+while the numerical part of the method consists of solving iteratively the
+transcendental dispersion relation together with the equation for the Alfv\'en
+resonance position. As an application of this method, we investigated the
+impact of flow on the phase velocity and resonant damping length of MHD kink
+waves. We consistently recover results in the thin boundary approximation
+obtained in previous studies. We have extended those results to the case of
+thick boundaries. We also explored the error associated with the use of the
+thin boundary approximation beyond its regime of applicability.",1901.10785v1
+2019-02-07,Violent relaxation in the Hamiltonian Mean Field model: I. Cold collapse and effective dissipation,"In $N$-body systems with long-range interactions mean-field effects dominate
+over binary interactions (collisions), so that relaxation to thermal
+equilibrium occurs on time scales that grow with $N$, diverging in the
+$N\to\infty$ limit. However, a faster and non-collisional relaxation process,
+referred to as violent relaxation, sets in when starting from generic initial
+conditions: collective oscillations (referred to as virial oscillations)
+develop and damp out on timescales not depending on the system's size. After
+the damping of such oscillations the system is found in a quasi-stationary
+state that survives virtually forever when the system is very large. During
+violent relaxation the distribution function obeys the collisionless Boltzmann
+(or Vlasov) equation, that, being invariant under time reversal, does not
+""naturally"" describe a relaxation process. Indeed, the dynamics is moved to
+smaller and smaller scales in phase space as time goes on, so that observables
+that do not depend on small-scale details appear as relaxed after a short time.
+We propose an approximation scheme to describe collisionless relaxation, based
+on the introduction of moments of the distribution function, and apply it to
+the Hamiltonian Mean Field (HMF) model. To the leading order, virial
+oscillations are equivalent to the motion of a particle in a one-dimensional
+potential. Inserting higher-order contributions in an effective way, inspired
+by the Caldeira-Leggett model of quantum dissipation, we derive a dissipative
+equation describing the damping of the oscillations, including a
+renormalization of the effective potential and yielding predictions for
+collective properties of the system after the damping in very good agreement
+with numerical simulations. Here we restrict ourselves to ""cold"" initial
+conditions; generic initial conditions will be considered in a forthcoming
+paper.",1902.02436v2
+2019-05-16,Boundary control of partial differential equations using frequency domain optimization techniques,"We present a frequency domain based $H_\infty$-control strategy to solve
+boundary control problems for systems governed by parabolic or hyperbolic
+partial differential equation, where controllers are constrained to be
+physically implementable and of simple structure suited for practical
+applications. The efficiency of our technique is demonstrated by controlling a
+reaction-diffusion equation with input delay, and a wave equation with boundary
+anti-damping.",1905.06786v1
+2019-05-20,Sharp Bounds for Oscillatory Integral Operators with Homogeneous Polynomial Phases,"We obtain sharp $L^p$ bounds for oscillatory integral operators with generic
+homogeneous polynomial phases in several variables. The phases considered in
+this paper satisfy the rank one condition which is an important notion
+introduced by Greenleaf, Pramanik and Tang. Under certain additional
+assumptions, we can establish sharp damping estimates with critical exponents
+to prove endpoint $L^p$ estimates.",1905.07980v1
+2019-06-19,Accurate Lindblad-Form Master Equation for Weakly Damped Quantum Systems Across All Regimes,"Realistic models of quantum systems must include dissipative interactions
+with an environment. For weakly-damped systems the Lindblad-form Markovian
+master equation is invaluable for this task due to its tractability and
+efficiency. This equation only applies, however, when the frequencies of any
+subset of the system's transitions are either equal (degenerate), or their
+differences are much greater than the transitions' linewidths (far-detuned).
+Outside of these two regimes the only available efficient description has been
+the Bloch-Redfield (B-R) master equation, the efficacy of which has long been
+controversial due to its failure to guarantee the positivity of the density
+matrix. The ability to efficiently simulate weakly-damped systems across all
+regimes is becoming increasingly important, especially in the area of quantum
+technologies. Here we solve this long-standing problem. We discover that a
+condition on the slope of the spectral density is sufficient to derive a
+Lindblad form master equation that is accurate for all regimes. We further show
+that this condition is necessary for weakly-damped systems to be described by
+the B-R equation or indeed any Markovian master equation. We thus obtain a
+replacement for the B-R equation over its entire domain of applicability that
+is no less accurate, simpler in structure, completely positive, allows
+simulation by efficient quantum trajectory methods, and unifies the previous
+Lindblad master equations. We also show via exact simulations that the new
+master equation can describe systems in which slowly-varying transition
+frequencies cross each other during the evolution. System identification tools,
+developed in systems engineering, play an important role in our analysis. We
+expect these tools to prove useful in other areas of physics involving complex
+systems.",1906.08279v2
+2019-07-10,Heuristic construction of codeword stabilized codes,"The family of codeword stabilized codes encompasses the stabilizer codes as
+well as many of the best known nonadditive codes. However, constructing optimal
+$n$-qubit codeword stabilized codes is made difficult by two main factors. The
+first of these is the exponential growth with $n$ of the number of graphs on
+which a code can be based. The second is the NP-hardness of the maximum clique
+search required to construct a code from a given graph. We address the second
+of these issues through the use of a heuristic clique finding algorithm. This
+approach has allowed us to find $((9,97\leq K\leq100,2))$ and $((11,387\leq
+K\leq416,2))$ codes, which are larger than any previously known codes. To
+address the exponential growth of the search space, we demonstrate that graphs
+that give large codes typically yield clique graphs with a large number of
+nodes. The number of such nodes can be determined relatively efficiently, and
+we demonstrate that $n$-node graphs yielding large clique graphs can be found
+using a genetic algorithm. This algorithm uses a novel spectral bisection based
+crossover operation that we demonstrate to be superior to more standard
+crossover operations. Using this genetic algorithm approach, we have found
+$((13,18,4))$ and $((13,20,4))$ codes that are larger than any previously known
+code. We also consider codes for the amplitude damping channel. We demonstrate
+that for $n\leq9$, optimal codeword stabilized codes correcting a single
+amplitude damping error can be found by considering standard form codes that
+detect one of only three of the $3^{n}$ possible equivalent error sets. By
+combining this error set selection with the genetic algorithm approach, we have
+found $((11,68))$ and $((11,80))$ codes capable of correcting a single
+amplitude damping error and $((11,4))$, $((12,4))$, $((13,8))$, and $((14,16))$
+codes capable of correcting two amplitude damping",1907.04537v2
+2019-07-10,Exponential stability for the nonlinear Schrödinger equation on a star-shaped network,"In this paper, we prove the exponential stability of the solution of the
+nonlinear dissipative Schr\""odinger equation on a star-shaped network and where
+the damping is localized on one branch and at the infinity.",1907.04950v1
+2019-07-22,Role of charge equilibration in multinucleon transfer in damped collisions of heavy ions,"In this work, the charge equilibration process has been analyzed within the
+Langevin-type dynamical approach. Its duration and energy dependence are
+discussed. We have analyzed the isotopic distributions of final products
+obtained in the isospin-asymmetric 58Ni,40Ca + 208Pb reactions. Comparison of
+58Ni,64Ni + 208Pb systems have been done in order to analyze the final yields
+of neutron-rich heavy nuclides.",1907.09352v1
+2019-09-25,Neutrino decoherence in a fermion and scalar background,"We consider the decoherence effects in the propagation of neutrinos in a
+background composed of a scalar particle and a fermion due to the non-forward
+neutrino scattering processes. Using a simple model for the coupling of the
+form $\bar f_R\nu_L\phi$ we calculate the contribution to the imaginary part of
+the neutrino self-energy arising from the non-forward neutrino scattering
+processes in such backgrounds, from which the damping terms are determined. In
+the case we are considering, in which the initial neutrino state is depleted
+but does not actually disappear (the initial neutrino transitions into a
+neutrino of a different flavor but does not decay into a $f\phi$ pair, for
+example), we associate the damping terms with decoherence effects. For this
+purpose we give a precise prescription to identify the decoherence terms, as
+used in the context of the master or Linblad equation, in terms of the damping
+terms we have obtained from the calculation of the imaginary part of the
+neutrino self-energy from the non-forward neutrino scattering processes. The
+results can be directly useful in the context of Dark Matter-neutrino
+interaction models in which the scalar and/or fermion constitute the
+dark-matter, and can also serve to guide the generalizations to other models
+and/or situations in which the decoherence effects in the propagation of
+neutrinos originate from the non-forward scattering processes may be important.
+As a guide to estimating such decoherence effects, the contributions to the
+absorptive part of the self-energy and the corresponding damping terms are
+computed explicitly in the context of the model we consider, for several
+limiting cases of the momentum distribution functions of the background
+particles.",1909.11271v2
+2019-10-15,Adversarial Examples for Models of Code,"Neural models of code have shown impressive results when performing tasks
+such as predicting method names and identifying certain kinds of bugs. We show
+that these models are vulnerable to adversarial examples, and introduce a novel
+approach for attacking trained models of code using adversarial examples. The
+main idea of our approach is to force a given trained model to make an
+incorrect prediction, as specified by the adversary, by introducing small
+perturbations that do not change the program's semantics, thereby creating an
+adversarial example. To find such perturbations, we present a new technique for
+Discrete Adversarial Manipulation of Programs (DAMP). DAMP works by deriving
+the desired prediction with respect to the model's inputs, while holding the
+model weights constant, and following the gradients to slightly modify the
+input code. We show that our DAMP attack is effective across three neural
+architectures: code2vec, GGNN, and GNN-FiLM, in both Java and C#. Our
+evaluations demonstrate that DAMP has up to 89% success rate in changing a
+prediction to the adversary's choice (a targeted attack) and a success rate of
+up to 94% in changing a given prediction to any incorrect prediction (a
+non-targeted attack). To defend a model against such attacks, we empirically
+examine a variety of possible defenses and discuss their trade-offs. We show
+that some of these defenses can dramatically drop the success rate of the
+attacker, with a minor penalty of 2% relative degradation in accuracy when they
+are not performing under attack. Our code, data, and trained models are
+available at https://github.com/tech-srl/adversarial-examples .",1910.07517v5
+2019-11-21,Special Itô maps and an $L^2$ Hodge theory for one forms on path spaces,"We prove a Kodaira-Hodge decomposition on differential 1-forms on the space
+of non-smooth paths over a Riemannian manifold, allowing us to define the
+corresponding first cohomology group. This uses the It\^o map of a Brownian
+system and damped stochastic parallel translation.",1911.09618v1
+2019-12-03,The global classical solution to compressible Euler system with velocity alignment,"In this paper, the compressible Euler system with velocity alignment and
+damping is considered, where the influence matrix of velocity alignment is not
+positive definite. Sound speed is used to reformulate the system into symmetric
+hyperbolic type. The global existence and uniqueness of smooth solution for
+small initial data is provided.",1912.01374v1
+2019-12-23,Signal Analysis using Born-Jordan-type Distribution,"In this note we exhibit recent advances in signal analysis via time-frequency
+distributions. New members of the Cohen class, generalizing the Wigner
+distribution, reveal to be effective in damping artefacts of some signals. We
+will survey their main properties and drawbacks and present open problems
+related to such phenomena.",1912.11387v1
+2020-01-15,Weak pseudo-bosons,"We show how the notion of {\em pseudo-bosons}, originally introduced as
+operators acting on some Hilbert space, can be extended to a distributional
+settings. In doing so, we are able to construct a rather general framework to
+deal with generalized eigenvectors of the multiplication and of the derivation
+operators. Connections with the quantum damped harmonic oscillator are also
+briefly considered.",2001.05219v1
+2020-02-18,Boundary feedback control of an anti-stable wave equation,"We discuss boundary control of a wave equation with a non-linear anti-damping
+boundary condition. We design structured finite-dimensional $H_\infty$-output
+feedback controllers which stabilize the infinite dimensional system
+exponentially in closed loop. The method is applied to control torsional
+vibrations in drilling systems with the goal to avoid slip-stick.",2002.07567v1
+2020-03-23,Critical exponent for the wave equation with a time-dependent scale invariant damping and a cubic convolution,"In the present paper, we study the Cauchy problem for the wave equation with
+a time-dependent scale invariant damping $\frac{2}{1+t}\partial_t v$ and a
+cubic convolution $(|x|^{-\gamma}*v^2)v$ with $\gamma\in
+\left(-\frac{1}{2},3\right)$ in three spatial dimension for initial data
+$\left(v(x,0),\partial_tv(x,0)\right)\in C^2(\mathbb{R}^3)\times
+C^1(\mathbb{R}^3)$ with a compact support, where $v=v(x,t)$ is an unknown
+function to the problem on $\mathbb{R}^3\times[0,T)$. Here $T$ denotes a
+maximal existence time of $v$.
+  The first aim of the present paper is to prove unique global existence of the
+solution to the problem and asymptotic behavior of the solution in the
+supercritical case $\gamma\in (0,3)$, and show a lower estimate of the lifespan
+in the critical or subcritical case $\gamma\in \left(-\frac{1}{2},0\right]$.
+The essential part for their proofs is to derive a weaker estimate under the
+weaker condition than the case without damping and to recover the weakness by
+the effect of the dissipative term.
+  The second aim of the present paper is to prove a small data blow-up and the
+almost sharp upper estimate of the lifespan for positive data with a compact
+support in the subcritical case $\gamma\in \left(-\frac{1}{2},0\right)$. The
+essential part for the proof is to refine the argument for the proof of Theorem
+6.1 in \cite{H20} to obtain the upper estimate of the lifespan.
+  Our two results determine that a critical exponent $\gamma_c$ which divides
+global existence and blow-up for small solutions is $0$, namely $\gamma_c=0$.
+As the result, we can see that the critical exponent shift from $2$ to $0$ due
+to the effect of the scale invariant damping term.",2003.10329v2
+2020-06-29,General decay and blow-up of solutions for a nonlinear wave equation with memory and fractional boundary damping terms,"The paper studies the global existence and general decay of solutions using
+Lyaponov functional for a nonlinear wave equation, taking into account the
+fractional derivative boundary condition and memory term. In addition, we
+establish the blow up of solutions with nonpositive initial energy.",2006.16325v1
+2020-07-19,Entanglement-Coherence and Discord-Coherence analytical relations for X states,"In this work we derive analytical relations between Entanglement and
+Coherence as well as between Discord and Coherence, for Bell-diagonal states
+and for X states, evolving under the action of several noise channels: Bit
+Flip, Phase Damping and Depolarizing. We demonstrate that for these families,
+Coherence is the fundamental correlation, that is: Coherence is necessary for
+the presence of Entanglement and Discord.",2007.09792v1
+2020-08-08,Linear Stability of the 2D Irrotational Circulation Flow around An Elliptical Cylinder,"In this article we prove a linear inviscid damping result with optimal decay
+rates of the 2D irrotational circulation flow around an elliptical cylinder. In
+our result, all components of the asymptotic velocity field do not vanish and
+the asymptotic flow lines are not ellipse any more.",2008.03451v1
+2020-09-01,On the first $δ$ Sct--roAp hybrid pulsator and the stability of p and g modes in chemically peculiar A/F stars,"Strong magnetic fields in chemically peculiar A-type (Ap) stars typically
+suppress low-overtone pressure modes (p modes) but allow high-overtone p modes
+to be driven. KIC 11296437 is the first star to show both. We obtained and
+analysed a Subaru spectrum, from which we show that KIC 11296437 has abundances
+similar to other magnetic Ap stars, and we estimate a mean magnetic field
+modulus of $2.8\pm0.5$ kG. The same spectrum rules out a double-lined
+spectroscopic binary, and we use other techniques to rule out binarity over a
+wide parameter space, so the two pulsation types originate in one $\delta$
+Sct--roAp hybrid pulsator. We construct stellar models depleted in helium and
+demonstrate that helium settling is second to magnetic damping in suppressing
+low-overtone p modes in Ap stars. We compute the magnetic damping effect for
+selected p and g modes, and find that modes with frequencies similar to the
+fundamental mode are driven for polar field strengths $\lesssim4$ kG, while
+other low-overtone p modes are driven for polar field strengths up to $\sim$1.5
+kG. We find that the high-order g modes commonly observed in $\gamma$ Dor stars
+are heavily damped by polar fields stronger than 1--4 kG, with the damping
+being stronger for higher radial orders. We therefore explain the observation
+that no magnetic Ap stars have been observed as $\gamma$ Dor stars. We use our
+helium-depleted models to calculate the $\delta$ Sct instability strip for
+metallic-lined A (Am) stars, and find that driving from a Rosseland mean
+opacity bump at $\sim$$5\times10^4$ K caused by the discontinuous H-ionization
+edge in bound-free opacity explains the observation of $\delta$ Sct pulsations
+in Am stars.",2009.00730v1
+2020-09-24,The eccentricity distribution of giant planets and their relation to super-Earths in the pebble accretion scenario,"Observations of the population of cold Jupiter planets ($r>$1 AU) show that
+nearly all of these planets orbit their host star on eccentric orbits. For
+planets up to a few Jupiter masses, eccentric orbits are thought to be the
+outcome of planet-planet scattering events taking place after gas dispersal. We
+simulate the growth of planets via pebble and gas accretion as well as the
+migration of multiple planetary embryos in their gas disc. We then follow the
+long-term dynamical evolution of our formed planetary system up to 100 Myr
+after gas disc dispersal. We investigate the importance of the initial number
+of protoplanetary embryos and different damping rates of eccentricity and
+inclination during the gas phase for the final configuration of our planetary
+systems. We constrain our model by comparing the final dynamical structure of
+our simulated planetary systems to that of observed exoplanet systems. Our
+results show that the initial number of planetary embryos has only a minor
+impact on the final orbital eccentricity distribution of the giant planets, as
+long as damping of eccentricity and inclination is efficient. If damping is
+inefficient (slow), systems with a larger initial number of embryos harbor
+larger average eccentricities. In addition, for slow damping rates, we observe
+that scattering events already during the gas disc phase are common and that
+the giant planets formed in these simulations match the observed giant planet
+eccentricity distribution best. These simulations also show that massive giant
+planets (above Jupiter mass) on eccentric orbits are less likely to host inner
+super-Earths as these get lost during the scattering phase, while systems with
+less massive giant planets on nearly circular orbits should harbor systems of
+inner super-Earths. Finally, our simulations predict that giant planets are on
+average not single, but live in multi-planet systems.",2009.11725v3
+2020-10-12,Period Estimates for Autonomous Evolution Equations with Lipschitz Nonlinearities,"We derive an estimate for the minimal period of autonomous strongly damped
+hyperbolic problems. Our result corresponds to the works by Yorke, Busenberg et
+al. for ordinary differential equations as well as Robinson and Vidal-Lopez for
+parabolic problems. A general approach is developed for treating both
+hyperbolic and parabolic problems. An example of application to a class of beam
+equations is provided.",2010.05829v1
+2020-12-16,Observation of anti-damping spin-orbit torques generated by in-plane and out-of-plane spin polarizations in MnPd3,"High spin-orbit torques (SOTs) generated by topological materials and heavy
+metals interfaced with a ferromagnetic layer show promise for next generation
+magnetic memory and logic devices. SOTs generated from the in-plane spin
+polarization along y-axis originated by the spin Hall and Edelstein effects can
+switch magnetization collinear with the spin polarization in the absence of
+external magnetic fields. However, an external magnetic field is required to
+switch the magnetization along x and z-axes via SOT generated by y-spin
+polarization. Here, we present that the above limitation can be circumvented by
+unconventional SOT in magnetron-sputtered thin film MnPd3. In addition to the
+conventional in-plane anti-damping-like torque due to the y-spin polarization,
+out-of-plane and in-plane anti-damping-like torques originating from z-spin and
+x-spin polarizations, respectively have been observed at room temperature. The
+spin torque efficiency corresponding to the y-spin polarization from MnPd3 thin
+films grown on thermally oxidized silicon substrate and post annealed at 400
+Deg C is 0.34 - 0.44. Remarkably, we have demonstrated complete external
+magnetic field-free switching of perpendicular Co layer via unconventional
+out-of-plane anti-damping-like torque from z-spin polarization. Based on the
+density functional theory calculations, we determine that the observed x- and
+z- spin polarizations with the in-plane charge current are due to the low
+symmetry of the (114) oriented MnPd3 thin films. Taken together, the new
+material reported here provides a path to realize a practical spin channel in
+ultrafast magnetic memory and logic devices.",2012.09315v1
+2021-02-15,A transmission problem for waves under time-varying delay and nonlinear weight,"This manuscript focus on in the transmission problem for one dimensional
+waves with nonlinear weights on the frictional damping and time-varying delay.
+We prove global existence of solutions using Kato's variable norm technique and
+we show the exponential stability by the energy method with the construction of
+a suitable Lyapunov functional.",2102.07829v1
+2021-05-16,Linear stability analysis of the Couette flow for the two dimensional non-isentropic compressible Euler equations,"This note is devoted to the linear stability of the Couette flow for the
+non-isentropic compressible Euler equations in a domain $\mathbb{T}\times
+\mathbb{R}$. Exploiting the several conservation laws originated from the
+special structure of the linear system, we obtain a Lyapunov type instability
+for the density, the temperature, the compressible part of the velocity field,
+and also obtain an inviscid damping for the incompressible part of the velocity
+field.",2105.07395v1
+2021-05-21,Effects of ambipolar diffusion on waves in the solar chromosphere,"The chromosphere is a partially ionized layer of the solar atmosphere, the
+transition between the photosphere where the gas motion is determined by the
+gas pressure and the corona dominated by the magnetic field. We study the
+effect of partial ionization for 2D wave propagation in a gravitationally
+stratified, magnetized atmosphere with properties similar to the solar
+chromosphere. We adopt an oblique uniform magnetic field in the plane of
+propagation with strength suitable for a quiet sun region. The theoretical
+model used is a single fluid magnetohydrodynamic approximation, where
+ion-neutral interaction is modeled by the ambipolar diffusion term. Magnetic
+energy can be converted into internal energy through the dissipation of the
+electric current produced by the drift between ions and neutrals. We use
+numerical simulations where we continuously drive fast waves at the bottom of
+the atmosphere. The collisional coupling between ions and neutrals decreases
+with the decrease of the density and the ambipolar effect becomes important.
+Fast waves excited at the base of the atmosphere reach the equipartition layer
+and reflect or transmit as slow waves. While the waves propagate through the
+atmosphere and the density drops, the waves steepen into shocks. The main
+effect of ambipolar diffusion is damping of the waves. We find that for the
+parameters chosen in this work, the ambipolar diffusion affects the fast wave
+before it is reflected, with damping being more pronounced for waves which are
+launched in a direction perpendicular to the magnetic field. Slow waves are
+less affected by ambipolar effects. The damping increases for shorter periods
+and larger magnetic field strengths. Small scales produced by the nonlinear
+effects and the superposition of different types of waves created at the
+equipartition height are efficiently damped by ambipolar diffusion.",2105.10285v1
+2021-05-26,Global Attractor for the Periodic Generalized Korteweg-de Vries Equation Through Smoothing,"We establish a smoothing result for the generalized KdV (gKdV) on the torus
+with polynomial non-linearity, damping, and forcing that matches the smoothing
+level for the gKdV at $H^1$. As a consequence, we establish the existence of a
+global attractor for this equation as well as its compactness in
+$H^s(\mathbb{T})$, $s\in (1,2).$",2105.13405v2
+2021-06-01,On the Well-Posedness of Two Driven-Damped Gross Pitaevskii-Type Models for Exciton-Polariton Condensates,"We study the well-posedness of two systems modeling the non-equilibrium
+dynamics of pumped decaying Bose-Einstein condensates. In particular, we
+present the local theory for rough initial data using the Fourier restricted
+norm method introduced by Bourgain. We extend the result globally for initial
+data in $L^2$.",2106.00438v1
+2021-06-11,Dynamics and Nonmonotonic Drag for Individually Driven Skyrmions,"We examine the motion of an individual skyrmion driven through an assembly of
+other skyrmions by a constant or increasing force in the absence of quenched
+disorder. The skyrmion behavior is determined by the ratio of the damping and
+Magnus terms, as expressed in terms of the intrinsic skyrmion Hall angle. For a
+fixed driving force in the damping dominated regime, the effective viscosity
+decreases monotonically with increasing skyrmion density, similar to what is
+observed in overdamped systems where it becomes difficult for the driven
+particle to traverse the surrounding medium at high densities. In contrast, in
+the Magnus dominated regime the velocity dependence on the density is
+nonmonotonic, and there is a regime in which the skyrmion moves faster with
+increasing density, as well as a pronounced speed-up effect in which a skyrmion
+traveling through a dense medium moves more rapidly than it would at low
+densities or in the single particle limit. At higher densities, the effective
+damping increases and the velocity decreases. The velocity-force curves in the
+Magnus-dominated regime show marked differences from those in the
+damping-dominated regimes. Under an increasing drive we find that there is a
+threshold force for skyrmion motion which increases with density. Additionally,
+the skyrmion Hall angle is drive dependent, starting near zero at the threshold
+for motion and increasing with increasing drive before reaching a saturation
+value, similar to the behavior found for skyrmions driven over quenched
+disorder. We map dynamic phase diagrams showing the threshold for motion,
+nonlinear flow, speed-up, and saturation regimes. We also find that in some
+cases, increasing the density can reduce the skyrmion Hall angle while
+producing a velocity boost, which could be valuable for applications.",2106.06093v1
+2021-06-23,On generalized damped Klein-Gordon equation with nonlinear memory,"In this paper we consider the Cauchy problem for linear dissipative
+generalized Klein-Gordon equations with nonlinear memory in the right hand
+side. Our goal is to study the effect of this nonlinearity on both the decay
+estimates of global solutions as well as the admissible range of the exponent
+p.",2106.12296v1
+2021-08-29,A note on the energy transfer in coupled differential systems,"We study the energy transfer in the linear system $$ \begin{cases} \ddot
+u+u+\dot u=b\dot v\\ \ddot v+v-\epsilon \dot v=-b\dot u \end{cases} $$ made by
+two coupled differential equations, the first one dissipative and the second
+one antidissipative. We see how the competition between the damping and the
+antidamping mechanisms affect the whole system, depending on the coupling
+parameter $b$.",2108.12776v1
+2021-08-30,Application of Rothe's method to a nonlinear wave equation on graphs,"We study a nonlinear wave equation on finite connected weighted graphs. Using
+Rothe's and energy methods, we prove the existence and uniqueness of solution
+under certain assumption. For linear wave equation on graphs, Lin and Xie
+\cite{Lin-Xie} obtained the existence and uniqueness of solution. The main
+novelty of this paper is that the wave equation we considered has the nonlinear
+damping term $|u_t|^{p-1}\cdot u_t$ ($p>1$).",2108.12980v1
+2021-09-08,Stabilisation of Waves on Product Manifolds by Boundary Strips,"We show that a transversely geometrically controlling boundary damping strip
+is sufficient but not necessary for $t^{-1/2}$-decay of waves on product
+manifolds. We give a general scheme to turn resolvent estimates for impedance
+problems on cross-sections to wave decay on product manifolds.",2109.03928v1
+2021-09-10,Smoothing effect and large time behavior of solutions to nonlinear elastic wave equations with viscoelastic term,"The Cauchy problem for a nonlinear elastic wave equations with viscoelastic
+damping terms is considered on the 3 dimensional whole space. Decay and
+smoothing properties of the solutions are investigated when the initial data
+are sufficiently small; and asymptotic profiles as $t \to \infty$ are also
+derived.",2109.04628v3
+2021-10-04,Overdamped limit at stationarity for non-equilibrium Langevin diffusions,"In this note, we establish that the stationary distribution of a possibly
+non-equilibrium Langevin diffusion converges, as the damping parameter goes to
+infinity (or equivalently in the Smoluchowski-Kramers vanishing mass limit),
+toward a tensor product of the stationary distribution of the corresponding
+overdamped process and of a Gaussian distribution.",2110.01238v2
+2021-11-17,Transverse kink oscillations of inhomogeneous prominence threads: numerical analysis and H$α$ forward modelling,"Prominence threads are very long and thin flux tubes which are partially
+filled with cold plasma. Observations have shown that transverse oscillations
+are frequent in these solar structures. The observations are usually
+interpreted as the fundamental kink mode, while the detection of the first
+harmonic remains elusive. Here, we aim to study how the density inhomogeneity
+in the longitudinal and radial directions modify the periods and damping times
+of kink oscillations, and how this effect would be reflected in observations.
+We solve the ideal magnetohydrodynamics equations through two different
+methods: a) performing 3D numerical simulations, and b) solving a 2D
+generalised eigenvalue problem. We study the dependence of the periods, damping
+times and amplitudes of transverse kink oscillations on the ratio between the
+densities at the centre and at the ends of the tube, and on the average
+density. We apply forward modelling on our 3D simulations to compute synthetic
+H$\alpha$ profiles. We confirm that the ratio of the period of the fundamental
+oscillation mode to the period of the first harmonic increases as the ratio of
+the central density to the footpoint density is increased or as the averaged
+density of the tube is decreased. We find that the damping times due to
+resonant absorption decrease as the central to footpoint density ratio
+increases. Contrary to the case of longitudinally homogeneous tubes, we find
+that the damping time to period ratio also increases as the density ratio is
+increased or the average density is reduced. We present snapshots and
+time-distance diagrams of the emission in the H$\alpha$ line. The results
+presented here have implications for the field of prominence seismology. While
+the H$\alpha$ emission can be used to detect the fundamental mode, the first
+harmonic is barely detectable in H$\alpha$. This may explain the lack of
+detections of the first harmonic.",2111.09036v1
+2021-11-26,A novel measurement of marginal Alfvén Eigenmode stability during high power auxiliary heating in JET,"The interaction of Alfv\'{e}n Eigenmodes (AEs) and energetic particles is one
+of many important factors determining the success of future tokamaks. In JET,
+eight in-vessel antennas were installed to actively probe stable AEs with
+frequencies ranging 25-250 kHz and toroidal mode numbers $\vert n \vert < 20$.
+During the 2019-2020 deuterium campaign, almost 7500 resonances and their
+frequencies $f_0$, net damping rates $\gamma < 0$, and toroidal mode numbers
+were measured in almost 800 plasma discharges. From a statistical analysis of
+this database, continuum and radiative damping are inferred to increase with
+edge safety factor, edge magnetic shear, and when including non-ideal effects.
+Both stable AE observations and their associated damping rates are found to
+decrease with $\vert n \vert$. Active antenna excitation is also found to be
+ineffective in H-mode as opposed to L-mode; this is likely due to the increased
+edge density gradient's effect on accessibility and ELM-related noise's impact
+on mode identification. A novel measurement is reported of a marginally stable,
+edge-localized Ellipticity-induced AE probed by the antennas during high-power
+auxiliary heating (ICRH and NBI) up to 25 MW. NOVA-K kinetic-MHD simulations
+show good agreement with experimental measurements of $f_0$, $\gamma$, and $n$,
+indicating the dominance of continuum and electron Landau damping in this case.
+Similar experimental and computational studies are planned for the recent
+hydrogen and ongoing tritium campaigns, in preparation for the upcoming DT
+campaign.",2111.13569v1
+2021-12-08,IGM damping wing constraints on reionisation from covariance reconstruction of two $z\gtrsim7$ QSOs,"Bright, high redshift ($z>6$) QSOs are powerful probes of the ionisation
+state of the intervening intergalactic medium (IGM). The detection of
+Ly$\alpha$ damping wing absorption imprinted in the spectrum of high-z QSOs can
+provide strong constraints on the epoch of reionisation (EoR). In this work, we
+perform an independent Ly$\alpha$ damping wing analysis of two known $z>7$
+QSOs; DESJ0252-0503 at $z=7.00$ (Wang et al.) and J1007+2115 at $z=7.51$ (Yang
+et al.). For this, we utilise our existing Bayesian framework which
+simultaneously accounts for uncertainties in: (i) the intrinsic Ly$\alpha$
+emission profile (reconstructed from a covariance matrix of measured emission
+lines; extended in this work to include NV) and (ii) the distribution of
+ionised (H\,{\scriptsize II}) regions within the IGM using a $1.6^3$ Gpc$^3$
+reionisation simulation. This approach is complementary to that used in the
+aforementioned works as it focuses solely redward of Ly$\alpha$ ($1218 <
+\lambda < 1230$\AA) making it more robust to modelling uncertainties while also
+using a different methodology for (i) and (ii). We find, for a fiducial EoR
+morphology, $\bar{x}_{\rm HI} = 0.64\substack{+0.19 \\ -0.23}$ (68 per cent) at
+$z=7$ and $\bar{x}_{\rm HI} = 0.27\substack{+0.21 \\ -0.17}$ at $z=7.51$
+consistent within $1\sigma$ to the previous works above, though both are
+slightly lower in amplitude. Following the inclusion of NV into our
+reconstruction pipeline, we perform a reanalysis of ULASJ1120+0641 at $z=7.09$
+(Mortlock et al.) and ULASJ1342+0928 at $z=7.54$ (Ba\~nados et al.) finding
+$\bar{x}_{\rm HI} = 0.44\substack{+0.23 \\ -0.24}$ at $z=7.09$ and
+$\bar{x}_{\rm HI} = 0.31\substack{+0.18 \\ -0.19}$ at $z=7.54$. Finally, we
+combine the QSO damping wing constraints for all four $z\gtrsim7$ QSOs to
+obtain a single, unified constraint of $\bar{x}_{\rm HI} = 0.49\substack{+0.11
+\\ -0.11}$ at $z=7.29$.",2112.04091v1
+2022-01-24,A blow-up result for a Nakao-type weakly coupled system with nonlinearities of derivative-type,"In this paper, we consider a weakly coupled system of a wave and damped
+Klein-Gordon equation with nonlinearities of derivative type. We prove a
+blow-up result for the Cauchy problem associated with this system for
+nonnegative and compactly supported data by means of an iteration argument.",2201.09462v1
+2022-03-11,On the small noise limit in the Smoluchowski-Kramers approximation of nonlinear wave equations with variable friction,"We study the validity of a large deviation principle for a class of
+stochastic nonlinear damped wave equations, of Klein-Gordon type, in the joint
+small mass and small noise limit. The friction term is assumed to be state
+dependent.",2203.05923v2
+2022-03-28,Composite Anderson acceleration method with dynamic window-sizes and optimized damping,"In this paper, we propose and analyze a set of fully non-stationary Anderson
+acceleration algorithms with dynamic window sizes and optimized damping.
+Although Anderson acceleration (AA) has been used for decades to speed up
+nonlinear solvers in many applications, most authors are simply using and
+analyzing the stationary version of Anderson acceleration (sAA) with fixed
+window size and a constant damping factor. The behavior and potential of the
+non-stationary version of Anderson acceleration methods remain an open
+question. Since most efficient linear solvers use composable algorithmic
+components. Similar ideas can be used for AA to solve nonlinear systems. Thus
+in the present work, to develop non-stationary Anderson acceleration
+algorithms, we first propose two systematic ways to dynamically alternate the
+window size $m$ by composition. One simple way to package sAA(m) with sAA(n) in
+each iteration is applying sAA(m) and sAA(n) separately and then average their
+results. It is an additive composite combination. The other more important way
+is the multiplicative composite combination, which means we apply sAA(m) in the
+outer loop and apply sAA(n) in the inner loop. By doing this, significant gains
+can be achieved. Secondly, to make AA to be a fully non-stationary algorithm,
+we need to combine these strategies with our recent work on the non-stationary
+Anderson acceleration algorithm with optimized damping (AAoptD), which is
+another important direction of producing non-stationary AA and nice performance
+gains have been observed. Moreover, we also investigate the rate of convergence
+of these non-stationary AA methods under suitable assumptions. Finally, our
+numerical results show that some of these proposed non-stationary Anderson
+acceleration algorithms converge faster than the stationary sAA method and they
+may significantly reduce the storage and time to find the solution in many
+cases.",2203.14627v1
+2022-03-28,The higher order nonlinear Schrödinger equation with quadratic nonlinearity on the real axis,"The initial value problem is considered for a higher order nonlinear
+Schr\""odinger equation with quadratic nonlinearity. Results on existence and
+uniqueness of weak solutions are obtained. In the case of an effective at
+infinity additional damping large-time decay of solutions without any smallness
+assumptions is also established. The main difficulty of the study is the
+non-smooth character of the nonlinearity.",2203.14830v1
+2022-04-03,Strong Solution of Modified Anistropic 3D-Navier-Stokes Equations,"In this paper we study the anisotropic incompressible Navier-Stokes equations
+with a logarithm damping $\alpha \log(e+|u|^2)|u|^2u$ in $H^{0.1}$, where we
+used new methods, new tools and Fourier analysis.",2204.01717v2
+2022-04-28,"Coupling between turbulence and solar-like oscillations: A combined Lagrangian PDF/SPH approach. II - Mode driving, damping and modal surface effect","The first paper of this series established a linear stochastic wave equation
+for solar-like p-modes, correctly taking the effect of turbulence thereon into
+account. In this second paper, we aim at deriving simultaneous expressions for
+the excitation rate, damping rate, and modal surface effect associated with any
+given p-mode, as an explicit function of the statistical properties of the
+turbulent velocity field. We reduce the stochastic wave equation to complex
+amplitude equations for the normal oscillating modes of the system. We then
+derive the equivalent Fokker-Planck equation for the real amplitudes and phases
+of all the oscillating modes of the system simultaneously. The effect of the
+finite-memory time of the turbulent fluctuations (comparable to the period of
+the modes) on the modes themselves is consistently and rigorously accounted
+for, by means of the simplified amplitude equation formalism. This formalism
+accounts for mutual linear mode coupling in full, and we then turn to the
+special single-mode case. This allows us to derive evolution equations for the
+mean energy and mean phase of each mode, from which the excitation rate, the
+damping rate, and the modal surface effect naturally arise.
+  We show that the expression for the excitation rate of the modes is identical
+to previous results obtained through a different modelling approach, thus
+supporting the validity of the formalism presented here. We also recover the
+fact that the damping rate and modal surface effect correspond to the real and
+imaginary part of the same single complex quantity. We explicitly separate the
+different physical contributions to these observables, in particular the
+turbulent pressure contribution and the joint effect of the
+pressure-rate-of-strain correlation and the turbulent dissipation. We show that
+the former dominates for high-frequency modes and the latter for low-frequency
+modes.",2204.13367v1
+2022-05-05,Blow-up solutions of damped Klein-Gordon equation on the Heisenberg group,"Inthisnote,weprovetheblow-upofsolutionsofthesemilineardamped Klein-Gordon
+equation in a finite time for arbitrary positive initial energy on the
+Heisenberg group. This work complements the paper [21] by the first author and
+Tokmagambetov, where the global in time well-posedness was proved for the small
+energy solutions.",2205.02705v1
+2022-05-06,Quaternion-based attitude stabilization via discrete-time IDA-PBC,"In this paper, we propose a new sampled-data controller for stabilization of
+the attitude dynamics at a desired constant configuration. The design is based
+on discrete-time interconnection and damping assignment (IDA) passivity-based
+control (PBC) and the recently proposed Hamiltonian representation of
+discrete-time nonlinear dynamics. Approximate solutions are provided with
+simulations illustrating performances.",2205.03086v1
+2022-05-23,Extended random-phase-approximation study of fragmentation of giant quadrupole resonance in $^{16}$O,"The damping of isoscalar giant quadrupole resonance in $^{16}$O is studied
+using extended random-phase-approximation approaches derived from the
+time-dependent density-matrix theory. It is pointed out that the effects of
+ground-state correlations bring strong fragmentation of quadrupole strength
+even if the number of two particle--two hole configurations is strongly
+limited.",2205.11654v2
+2022-06-21,Nonlinear Compton scattering and nonlinear Breit-Wheeler pair production including the damping of particle states,"In the presence of an electromagnetic background plane-wave field, electron,
+positron, and photon states are not stable, because electrons and positrons
+emit photons and photons decay into electron-positron pairs. This decay of the
+particle states leads to an exponential damping term in the probabilities of
+single nonlinear Compton scattering and nonlinear Breit-Wheeler pair
+production. In this paper we investigate analytically and numerically the
+probabilities of nonlinear Compton scattering and nonlinear Breit-Wheeler pair
+production including the particle states' decay. For this we first compute
+spin- and polarization-resolved expressions of the probabilities, provide some
+of their asymptotic behaviors and show that the results of the total
+probabilities are independent of the spin and polarization bases. Then, we
+present several plots of the total and differential probabilities for different
+pulse lengths and for different spin and polarization quantum numbers. We
+observe that it is crucial to take into account the damping of the states in
+order for the probabilities to stay always below unity and we show that the
+damping factors also scale with the intensity and pulse duration of the
+background field. In the case of nonlinear Compton scattering we show
+numerically that the total probability behaves like a Poissonian distribution
+in the regime where the photon recoil is negligible. In all considered cases,
+the kinematic conditions are such that the final particles momenta transverse
+to the propagation direction of the plane wave are always much smaller than the
+particles longitudinal momenta and the main spread of the momentum distribution
+on the transverse plane is along the direction of the plane-wave electric
+field.",2206.10345v2
+2022-06-23,Nonlinear Landau damping for the 2d Vlasov-Poisson system with massless electrons around Penrose-stable equilibria,"In this paper, we prove the nonlinear asymptotic stability of the
+Penrose-stable equilibria among solutions of the $2d$ Vlasov-Poisson system
+with massless electrons.",2206.11744v2
+2022-08-25,Polynomial energy decay rate of a 2D Piezoelectric beam with magnetic effect on a rectangular domain without geometric conditions,"In this paper, we investigate the stability of coupled equations modelling a
+2D piezoelectric beam with magnetic effect with only one local viscous damping
+on a rectangular domain without geometric conditions. We prove that the energy
+of the system decays polynomially with the rate 1/t .",2208.12012v1
+2022-10-12,Backward problem for the 1D ionic Vlasov-Poisson equation,"In this paper, we study the backward problem for the one-dimensional
+Vlasov-Poisson system with massless electrons, and we show the Landau damping
+by fixing the asymptotic behaviour of our solution.",2210.06123v2
+2022-10-28,"Oblique Quasi-Kink Modes in Solar Coronal Slabs Embedded in an Asymmetric Magnetic Environment: Resonant Damping, Phase and Group Diagrams","There has been considerable interest in magnetoacoustic waves in static,
+straight, field-aligned, one-dimensional equilibria where the exteriors of a
+magnetic slab are different between the two sides. We focus on trapped,
+transverse fundamental, oblique quasi-kink modes in pressureless setups where
+the density varies continuously from a uniform interior (with density
+$\rho_{\rm i}$) to a uniform exterior on either side (with density $\rho_{\rm
+L}$ or $\rho_{\rm R}$), assuming $\rho_{\rm L}\le\rho_{\rm R}\le\rho_{\rm i}$.
+The continuous structuring and oblique propagation make our study new relative
+to pertinent studies, and lead to wave damping via the Alfv$\acute{\rm e}$n
+resonance. We compute resonantly damped quasi-kink modes as resistive
+eigenmodes, and isolate the effects of system asymmetry by varying $\rho_{\rm
+i}/\rho_{\rm R}$ from the ``Fully Symmetric'' ($\rho_{\rm i}/\rho_{\rm
+R}=\rho_{\rm i}/\rho_{\rm L}$) to the ``Fully Asymmetric'' limit ($\rho_{\rm
+i}/\rho_{\rm R}=1$). We find that the damping rates possess a nonmonotonic
+$\rho_{\rm i}/\rho_{\rm R}$-dependence as a result of the difference between
+the two Alfv$\acute{\rm e}$n continua, and resonant absorption occurs only in
+one continuum when $\rho_{\rm i}/\rho_{\rm R}$ is below some threshold. We also
+find that the system asymmetry results in two qualitatively different regimes
+for the phase and group diagrams. The phase and group trajectories lie
+essentially on the same side (different sides) relative to the equilibrium
+magnetic field when the configuration is not far from a ``Fully Asymmetric''
+(``Fully Symmetric'') one. Our numerical results are understood by making
+analytical progress in the thin-boundary limit, and discussed for imaging
+observations of axial standing modes and impulsively excited wavetrains.",2210.16091v1
+2022-11-02,Data-driven modeling of Landau damping by physics-informed neural networks,"Kinetic approaches are generally accurate in dealing with microscale plasma
+physics problems but are computationally expensive for large-scale or
+multiscale systems. One of the long-standing problems in plasma physics is the
+integration of kinetic physics into fluid models, which is often achieved
+through sophisticated analytical closure terms. In this paper, we successfully
+construct a multi-moment fluid model with an implicit fluid closure included in
+the neural network using machine learning. The multi-moment fluid model is
+trained with a small fraction of sparsely sampled data from kinetic simulations
+of Landau damping, using the physics-informed neural network (PINN) and the
+gradient-enhanced physics-informed neural network (gPINN). The multi-moment
+fluid model constructed using either PINN or gPINN reproduces the time
+evolution of the electric field energy, including its damping rate, and the
+plasma dynamics from the kinetic simulations. In addition, we introduce a
+variant of the gPINN architecture, namely, gPINN$p$ to capture the Landau
+damping process. Instead of including the gradients of all the equation
+residuals, gPINN$p$ only adds the gradient of the pressure equation residual as
+one additional constraint. Among the three approaches, the gPINN$p$-constructed
+multi-moment fluid model offers the most accurate results. This work sheds
+light on the accurate and efficient modeling of large-scale systems, which can
+be extended to complex multiscale laboratory, space, and astrophysical plasma
+physics problems.",2211.01021v3
+2022-11-04,New Clues About Light Sterile Neutrinos: Preference for Models with Damping Effects in Global Fits,"This article reports global fits of short-baseline neutrino data to
+oscillation models involving light sterile neutrinos. In the commonly-used 3+1
+plane wave model, there is a well-known 4.9$\sigma$ tension between data sets
+sensitive to appearance versus disappearance of neutrinos. We find that models
+that damp the oscillation prediction for the reactor data sets, especially at
+low energy, substantially improve the fits and reduce the tension. We consider
+two such scenarios. The first scenario introduces the quantum mechanical
+wavepacket effect that accounts for the source size in reactor experiments into
+the 3+1 model. We find that inclusion of the wavepacket effect greatly improves
+the overall fit compared to a 3$\nu$ model by $\Delta \chi^2/$DOF$=61.1/4$
+($7.1\sigma$ improvement) with best-fit $\Delta m^2=1.4$ eV$^2$ and wavepacket
+length of 67fm. The internal tension is reduced to 3.4$\sigma$. If reactor-data
+only is fit, then the wavepacket preferred length is 91 fm ($>20$ fm at 99\%
+CL). The second model introduces oscillations involving sterile flavor and
+allows the decay of the heaviest, mostly sterile mass state, $\nu_4$. This
+model introduces a damping term similar to the wavepacket effect, but across
+all experiments. Compared to a three-neutrino fit, this has a $\Delta
+\chi^2/$DOF$=60.6/4$ ($7\sigma$ improvement) with preferred $\Delta m^2=1.4$
+eV$^2$ and decay $\Gamma = 0.35$ eV$^2$. The internal tension is reduced to
+3.7$\sigma$.
+  For many years, the reactor event rates have been observed to have structure
+that deviates from prediction. Community discussion has focused on an excess
+compared to prediction observed at 5 MeV; however, other deviations are
+apparent. This structure has $L$ dependence that is well-fit by the damped
+models. Before assuming this points to new physics, we urge closer examination
+of systematic effects that could lead to this $L$ dependence.",2211.02610v5
+2022-12-07,A recipe for orbital eccentricity damping in the type-I regime for low viscosity 2D-discs,"It is known that gap opening depends on the disc's viscosity; however,
+eccentricity damping formulas have only been derived at high viscosities,
+ignoring partial gap opening. We aim at obtaining a simple formula to model
+$e$-damping of the type-I regime in low viscosity discs, where even small
+planets may start opening partial. We perform high resolution 2D locally
+isothermal hydrodynamical simulations of planets with varying masses on fixed
+orbits in discs with varying aspect ratios and viscosities. We determine the
+torque and power felt by the planet to derive migration and eccentricity
+damping timescales. We first find a lower limit to the gap depths below which
+vortices appear; this happens roughly at the transition between type-I and
+type-II regimes. For the simulations that remain stable, we obtain a fit to the
+observed gap depth in the limit of vanishing eccentricities that is similar to
+the one currently used in the literature but is accurate down to
+$\alpha=3.16\times 10^{-5}$. We record the $e$-damping efficiency as a function
+of the observed gap depth and $e$: when the planet has opened a deep enough
+gap, a linear trend is observed independently of $e$; at shallower gaps this
+linear trend is preserved at low $e$, while it deviates to more efficient
+damping when $e$ is comparable to the disc's scale height. Both trends can be
+understood on theoretical grounds and are reproduced by a simple fitting
+formula. Our combined fits yield a simple recipe to implement type-I
+$e$-damping in $N$-body for partial gap opening planets that is consistent with
+high-resolution 2D hydro-simulations. The typical error of the fit is of the
+order of a few percent, and lower than the error of type-I torque formulas
+widely used in the literature. This will allow a more self-consistent treatment
+of planet-disc interactions of the type-I regime for population synthesis
+models at low viscosities.",2212.03608v1
+2022-12-10,Linear stabilization for a degenerate wave equation in non divergence form with drift,"We consider a degenerate wave equation in one dimension, with drift and in
+presence of a leading operator which is not in divergence form. We impose a
+homogeneous Dirichlet boundary condition where the degeneracy occurs and a
+boundary damping at the other endpoint. We provide some conditions for the
+uniform exponential decay of solutions for the associated Cauchy problem.",2212.05264v1
+2022-12-31,"On the stability of shear flows in bounded channels, II: non-monotonic shear flows","We give a proof of linear inviscid damping and vorticity depletion for
+non-monotonic shear flows with one critical point in a bounded periodic
+channel. In particular, we obtain quantitative depletion rates for the
+vorticity function without any symmetry assumptions.",2301.00288v2
+2023-03-18,Spin waves in a superconductor,"Spin waves that can propagate in normal and superconducting metals are
+investigated. Unlike normal metals, the velocity of spin waves becomes
+temperature-dependent in a superconductor. The low frequency spin waves survive
+within the narrow region below the superconducting transition temperature. At
+low temperatures the high frequency waves alone can propagate with an
+additional damping due to pair-breaking.",2303.10468v1
+2023-04-07,Echo disappears: momentum term structure and cyclic information in turnover,"We extract cyclic information in turnover and find it can explain the
+momentum echo. The reversal in recent month momentum is the key factor that
+cancels out the recent month momentum and excluding it makes the echo regress
+to a damped shape. Both rational and behavioral theories can explain the
+reversal. This study is the first explanation of the momentum echo in U.S.
+stock markets.",2304.03437v1
+2023-04-26,Plasma echoes in graphene,"Plasma echo is a dramatic manifestation of plasma damping process
+reversibility. In this paper we calculate temporal and spatial plasma echoes in
+graphene in the acoustic plasmon regime when echoes dominate over plasmon
+emission. We show an extremely strong spatial echo response and discuss how
+electron collisions reduce the echo. We also discuss differences between
+various electron dispersions, and differences between semiclassical and quantum
+model of echoes.",2304.13440v1
+2023-06-01,JWST Measurements of Neutral Hydrogen Fractions and Ionized Bubble Sizes at $z=7-12$ Obtained with Ly$α$ Damping Wing Absorptions in 26 Bright Continuum Galaxies,"We present volume-averaged neutral hydrogen fractions $x_{\rm \HI}$ and
+ionized bubble radii $R_{\rm b}$ measured with Ly$\alpha$ damping wing
+absorption of galaxies at the epoch of reionization. We combine JWST/NIRSpec
+spectra taken by CEERS, GO-1433, DDT-2750, and JADES programs, and obtain a
+sample containing 26 bright UV-continuum ($M_{\rm UV}<-18.5~{\rm mag}$)
+galaxies at $7<z<12$. We construct 4 composite spectra binned by redshift, and
+find the clear evolution of softening break towards high redshift at the
+rest-frame $1216$ {\AA}, suggesting the increase of Ly$\alpha$ damping wing
+absorption. We estimate Ly$\alpha$ damping wing absorption in the galaxy
+spectra with realistic templates including Ly$\alpha$ emission and
+circum-galactic medium absorptions. Assuming the standard inside-out
+reionization picture having an ionized bubble with radius $R_b$ around a galaxy
+embedded in the intergalactic medium with $x_{\rm \HI}$, we obtain $x_{\rm
+\HI}$ ($R_{\rm b}$) values generally increasing (decreasing) from $x_{\rm
+\HI}={0.54}^{+0.13}_{-0.54}$ to ${0.94}^{+0.06}_{-0.41}$ ($\log R_{\rm
+b}={1.89}^{+0.49}_{-1.54}$ to ${-0.72}^{+1.57}_{-0.28}$ comoving Mpc) at
+redshift $7.12^{+0.06}_{-0.08}$ to $10.28^{+1.12}_{-1.40}$. The redshift
+evolution of $x_{\rm \HI}$ indicates a moderately late reionization history
+consistent with the one previously suggested from the electron scattering of
+cosmic microwave background and the evolution of UV luminosity function with an
+escape fraction $f_{\rm esc}\sim 0.2$. Our ${R_{\rm b}}$ measurements suggest
+that bubble sizes could be up to a few dex larger than the cosmic average
+values estimated by analytic calculations for a given $x_{\rm \HI}$, while our
+$R_{\rm b}$ measurements are roughly comparable with the values for merged
+ionized bubbles around bright galaxies predicted by recent numerical
+simulations.",2306.00487v2
+2023-06-20,New results on controllability and stability for degenerate Euler-Bernoulli type equations,"In this paper we study the controllability and the stability for a degenerate
+beam equation in divergence form via the energy method. The equation is clamped
+at the left end and controlled by applying a shearing force or a damping at the
+right end.",2306.11851v3
+2023-07-18,"Nonlinear feedback, double bracket dissipation and port control of Lie-Poisson systems","Methods from controlled Lagrangians, double bracket dissipation and
+interconnection and damping assignment -- passivity based control (IDA-PBC) are
+used to construct nonlinear feedback controls which (asymptotically) stabilize
+previously unstable equilibria of Lie-Poisson Hamiltonian systems. The results
+are applied to find an asymptotically stabilizing control for the rotor driven
+satellite, and a stabilizing control for Hall magnetohydrodynamic flow.",2307.09235v1
+2023-08-01,Aerodynamics of the square-back Ahmed body under rainfall conditions,"We report an experimental investigation about the aerodynamics of a
+simplified road vehicle, the so-called square-back Ahmed body, under rainfall
+conditions. A particular emphasis is put on the evolution of the body base
+pressure distribution with respect to the operating conditions. It is found
+that rainfall significantly damps both mean base pressure drag and wake
+dynamics in comparison to dry conditions.",2308.00276v1
+2023-09-11,Study of damped oscillating structures from charged and neutral K-meson electromagnetic form factors data,"The damped oscillating structures (OS) were recently revealed in the proton
+""effective"" form factor (FF) data. For the time being they can be neither
+confirmed nor disproved by investigations of timelike data on the individual
+proton electric and proton magnetic FFs because their precision and reliability
+(especially of the proton electric FF data) has not achieved required level for
+this aim. On the other hand, conjectures that the OS are direct manifestations
+of the quark-gluon structure of the proton indicate that they must not be
+specific only for the proton and neutron, but that they should be present also
+for other hadrons. This opens a plausibility to find damped oscillatory
+structures also from the EM FFs data of such hadrons, for which adequate EM FFs
+data exist, by using the same procedure as for the proton. Consequently in this
+paper damped oscillatory structures are investigated in the EM FFs data of the
+charged and neutral $K$-mesons to be extracted from the corresponding
+production cross sections, $\sigma^{bare}_{tot}(e^+e^-\to K^+ K^-)$ measured
+from the threshold up to 64 GeV$^2$ and $\sigma^{bare}_{tot}(e^+e^-\to K_s
+K_L)$ measured from the threshold up to 9.5 GeV$^2$ of the total c.m. energy
+squared. The following results have been obtained. If the charged and neutral
+K-meson EM FFs timelike data are described by the three parametric formula by
+means of which OS have been revealed from the ""effective"" proton FF data then
+OS appear. If physically well founded Unitary and Analytic model of the K-meson
+EM structure is used for a description of the charged K-meson EM FFs data, no
+OS are visible. However, in the case of the neutral K-meson EM FF data one
+cannot make a definite decision. The overall results indicate that OS obtained
+from the ""effective"" proton FF data are likely an artefact of the three
+parametric formula which does not describe these data well.",2309.05354v1
+2023-10-31,"Variational principle for a damped, quadratically interacting particle chain with nonconservative forcing","A method for designing variational principles for the dynamics of a possibly
+dissipative and non-conservatively forced chain of particles is demonstrated.
+Some qualitative features of the formulation are discussed.",2311.00106v2
+2024-01-30,Linear stability analysis of the Couette flow for the 2D Euler-Poisson system,"This paper is concerned with the linear stability analysis for the Couette
+flow of the Euler-Poisson system for both ionic fluid and electronic fluid in
+the domain $\bb{T}\times\bb{R}$. We establish the upper and lower bounds of the
+linearized solutions of the Euler-Poisson system near Couette flow. In
+particular, the inviscid damping for the solenoidal component of the velocity
+is obtained.",2401.17102v1
+2024-03-21,Non-resonant invariant foliations of quasi-periodically forced systems,"We show the existence and uniqueness of invariant foliations about invariant
+tori in analytic discrete-time dynamical systems. The parametrisation method is
+used prove the result. Our theory is a foundational block of data-driven model
+order reduction, that can only be carried out using invariant foliations. The
+theory is illustrated by two mechanical examples, where instantaneous
+frequencies and damping ratios are calculated about the invariant tori.",2403.14771v1
+2024-04-03,"Comment on ""Machine learning conservation laws from differential equations""","In lieu of abstract, first paragraph reads: Six months after the author
+derived a constant of motion for a 1D damped harmonic oscillator [1], a similar
+result appeared by Liu, Madhavan, and Tegmark [2, 3], without citing the
+author. However, their derivation contained six serious errors, causing both
+their method and result to be incorrect. In this Comment, those errors are
+reviewed.",2404.02896v1
+2007-03-01,Stellar Kinematics in the Complicated Inner Spheroid of M31: Discovery of Substructure Along the Southeastern Minor Axis and its Relationship to the Giant Southern Stream,"We present the discovery of a kinematically-cold stellar population along the
+SE minor axis of the Andromeda galaxy (M31) that is likely the forward
+continuation of M31's giant southern stream. This discovery was made in the
+course of an on-going spectroscopic survey of red giant branch (RGB) stars in
+M31 using the DEIMOS instrument on the Keck II 10-m telescope. Stellar
+kinematics are investigated in eight fields located 9-30 kpc from M31's center
+(in projection). A likelihood method based on photometric and spectroscopic
+diagnostics is used to isolate confirmed M31 RGB stars from foreground Milky
+Way dwarf stars: for the first time, this is done without using radial velocity
+as a selection criterion, allowing an unbiased study of M31's stellar
+kinematics. The radial velocity distribution of the 1013 M31 RGB stars shows
+evidence for the presence of two components. The broad (hot) component has a
+velocity dispersion of 129 km/s and presumably represents M31's virialized
+spheroid. A significant fraction (19%) of the population is in a narrow (cold)
+component centered near M31's systemic velocity with a velocity dispersion that
+decreases with increasing radial distance, from 55.5 km/s at R_proj=12 kpc to
+10.6 km/s at R_proj=18 kpc. The spatial and velocity distribution of the cold
+component matches that of the ""Southeast shelf"" predicted by the Fardal et al.
+(2007) orbital model of the progenitor of the giant southern stream. The
+metallicity distribution of the cold component matches that of the giant
+southern stream, but is about 0.2 dex more metal rich on average than that of
+the hot spheroidal component. We discuss the implications of our discovery on
+the interpretation of the intermediate-age spheroid population found in this
+region in recent ultra-deep HST imaging studies.",0703029v3
+2017-02-26,Limits on the ultra-bright Fast Radio Burst population from the CHIME Pathfinder,"We present results from a new incoherent-beam Fast Radio Burst (FRB) search
+on the Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder. Its
+large instantaneous field of view (FoV) and relative thermal insensitivity
+allow us to probe the ultra-bright tail of the FRB distribution, and to test a
+recent claim that this distribution's slope, $\alpha\equiv-\frac{\partial \log
+N}{\partial \log S}$, is quite small. A 256-input incoherent beamformer was
+deployed on the CHIME Pathfinder for this purpose. If the FRB distribution were
+described by a single power-law with $\alpha=0.7$, we would expect an FRB
+detection every few days, making this the fastest survey on sky at present. We
+collected 1268 hours of data, amounting to one of the largest exposures of any
+FRB survey, with over 2.4\,$\times$\,10$^5$\,deg$^2$\,hrs. Having seen no
+bursts, we have constrained the rate of extremely bright events to
+$<\!13$\,sky$^{-1}$\,day$^{-1}$ above $\sim$\,220$\sqrt{(\tau/\rm ms)}$ Jy\,ms
+for $\tau$ between 1.3 and 100\,ms, at 400--800\,MHz. The non-detection also
+allows us to rule out $\alpha\lesssim0.9$ with 95$\%$ confidence, after
+marginalizing over uncertainties in the GBT rate at 700--900\,MHz, though we
+show that for a cosmological population and a large dynamic range in flux
+density, $\alpha$ is brightness-dependent. Since FRBs now extend to large
+enough distances that non-Euclidean effects are significant, there is still
+expected to be a dearth of faint events and relative excess of bright events.
+Nevertheless we have constrained the allowed number of ultra-intense FRBs.
+While this does not have significant implications for deeper, large-FoV surveys
+like full CHIME and APERTIF, it does have important consequences for other
+wide-field, small dish experiments.",1702.08040v2
+2019-04-01,"Astro2020 Science White Paper: Construction of an L* Galaxy: the Transformative Power of Wide Fields for Revealing the Past, Present and Future of the Great Andromeda System","The Great Andromeda Galaxy (M31) is the nexus of the near-far galaxy
+evolution connection and a principal data point for near-field cosmology. Due
+to its proximity (780 kpc), M31 can be resolved into individual stars like the
+Milky Way (MW). Unlike the MW, we have the advantage of a global view of M31,
+enabling M31 to be observed with techniques that also apply to more distant
+galaxies. Moreover, recent evidence suggests that M31 may have survived a major
+merger within the last several Gyr, shaping the morphology of its stellar halo
+and triggering a starburst, while leaving the stellar disk largely intact. The
+MW and M31 thus provide complementary opportunities for in-depth studies of the
+disks, halos, and satellites of L* galaxies.
+  Our understanding of the M31 system will be transformed in the 2020s if they
+include wide field facilities for both photometry (HST-like sensitivity and
+resolution) and spectroscopy (10-m class telescope, >1 sq. deg. field, highly
+multiplexed, R~ 3000 to 6000). We focus here on the power of these facilities
+to constrain the past, present, and future merger history of M31, via
+chemo-dynamical analyses and star formation histories of phase-mixed stars
+accreted at early times, as well as stars in surviving tidal debris features,
+M31's extended disk, and intact satellite galaxies that will eventually be
+tidally incorporated into the halo. This will yield an unprecedented view of
+the hierarchical formation of the M31 system and the subhalos that built it
+into the L* galaxy we observe today.",1904.01074v1
+2021-09-28,Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System,"We present updated radial-velocity (RV) analyses of the AU Mic system. AU Mic
+is a young (22 Myr) early M dwarf known to host two transiting planets -
+$P_{b}\sim8.46$ days, $R_{b}=4.38_{-0.18}^{+0.18}\ R_{\oplus}$,
+$P_{c}\sim18.86$ days, $R_{c}=3.51_{-0.16}^{+0.16}\ R_{\oplus}$. With visible
+RVs from CARMENES-VIS, CHIRON, HARPS, HIRES, {\sc
+{\textsc{Minerva}}}-Australis, and TRES, as well as near-infrared (NIR) RVs
+from CARMENES-NIR, CSHELL, IRD, iSHELL, NIRSPEC, and SPIRou, we provide a
+$5\sigma$ upper limit to the mass of AU Mic c of $M_{c}\leq20.13\ M_{\oplus}$
+and present a refined mass of AU Mic b of $M_{b}=20.12_{-1.57}^{+1.72}\
+M_{\oplus}$. Used in our analyses is a new RV modeling toolkit to exploit the
+wavelength dependence of stellar activity present in our RVs via
+wavelength-dependent Gaussian processes. By obtaining near-simultaneous visible
+and near-infrared RVs, we also compute the temporal evolution of RV-``color''
+and introduce a regressional method to aid in isolating Keplerian from stellar
+activity signals when modeling RVs in future works. Using a multi-wavelength
+Gaussian process model, we demonstrate the ability to recover injected planets
+at $5\sigma$ significance with semi-amplitudes down to $\approx$
+10\,m\,s$^{-1}$ with a known ephemeris, more than an order of magnitude below
+the stellar activity amplitude. However, we find that the accuracy of the
+recovered semi-amplitudes is $\sim$50\% for such signals with our model.",2109.13996v1
+2022-03-04,Scaling K2. V. Statistical Validation of 60 New Exoplanets From K2 Campaigns 2-18,"The NASA K2 mission, salvaged from the hardware failures of the Kepler
+telescope, has continued Kepler's planet-hunting success. It has revealed
+nearly 500 transiting planets around the ecliptic plane, many of which are the
+subject of further study, and over 1000 additional candidates. Here we present
+the results of an ongoing project to follow-up and statistically validate new
+K2 planets, in particular to identify promising new targets for further
+characterization. By analyzing the reconnaissance spectra, high-resolution
+imaging, centroid variations, and statistical likelihood of the signals of 91
+candidates, we validate 60 new planets in 46 systems. These include: a number
+of planets amenable to transmission spectroscopy (K2-384 f, K2-387 b, K2-390 b,
+K2-403 b, and K2-398 c), emission spectroscopy (K2-371 b, K2-370 b, and K2-399
+b), and both (K2-405 b and K2-406 b); several systems with planets in or close
+to mean motion resonances (K2-381, K2-398) including a compact, TRAPPIST-1-like
+system of five small planets orbiting a mid-M dwarf (K2-384); an ultra-short
+period sub-Saturn in the hot Saturn desert (K2-399 b); and a super-Earth
+orbiting a moderately bright (V=11.93), metal-poor ([Fe/H]=-0.579+/-0.080) host
+star (K2-408 b). In total we validate planets around 4 F stars, 26 G stars, 13
+K stars, and 3 M dwarfs. In addition, we provide a list of 37 vetted planet
+candidates that should be prioritized for future follow-up observation in order
+to be confirmed or validated.",2203.02087v2
+2007-03-08,Tensor Microwave Background Fluctuations for Large Multipole Order,"We present approximate formulas for the tensor BB, EE, TT, and TE multipole
+coefficients for large multipole order l. The error in using the approximate
+formula for the BB multipole coefficients is less than cosmic variance for
+l>10. These approximate formulas make various qualitative properties of the
+calculated multipole coefficients transparent: specifically, they show that,
+whatever values are chosen for cosmological parameters, the tensor EE multipole
+coefficients will always be larger than the BB coefficients for all l>15, and
+that these coefficients will approach each other for l<<100. These
+approximations also make clear how these multipole coefficients depend on
+cosmological parameters.",0703179v2
+1997-11-18,The fourth virial coefficient of anyons,"We have computed by a Monte Carlo method the fourth virial coefficient of
+free anyons, as a function of the statistics angle theta. It can be fitted by a
+four term Fourier series, in which two coefficients are fixed by the known
+perturbative results at the boson and fermion points. We compute partition
+functions by means of path integrals, which we represent diagrammatically in
+such a way that the connected diagrams give the cluster coefficients. This
+provides a general proof that all cluster and virial coefficients are finite.
+We give explicit polynomial approximations for all path integral contributions
+to all cluster coefficients, implying that only the second virial coefficient
+is statistics dependent, as is the case for two-dimensional exclusion
+statistics. The assumption leading to these approximations is that the tree
+diagrams dominate and factorize.",9711169v1
+2006-04-04,Modified Sonine approximation for the Navier-Stokes transport coefficients of a granular gas,"Motivated by the disagreement found at high dissipation between simulation
+data for the heat flux transport coefficients and the expressions derived from
+the Boltzmann equation by the standard first Sonine approximation [Brey et al.,
+Phys. Rev. E 70, 051301 (2004); J. Phys.: Condens. Matter 17, S2489 (2005)], we
+implement in this paper a modified version of the first Sonine approximation in
+which the Maxwell-Boltzmann weight function is replaced by the homogeneous
+cooling state distribution. The structure of the transport coefficients is
+common in both approximations, the distinction appearing in the coefficient of
+the fourth cumulant $a_2$. Comparison with computer simulations shows that the
+modified approximation significantly improves the estimates for the heat flux
+transport coefficients at strong dissipation. In addition, the slight
+discrepancies between simulation and the standard first Sonine estimates for
+the shear viscosity and the self-diffusion coefficient are also partially
+corrected by the modified approximation. Finally, the extension of the modified
+first Sonine approximation to the transport coefficients of the Enskog kinetic
+theory is presented.",0604079v2
+1992-03-02,Can fusion coefficients be calculated from the depth rule ?,"The depth rule is a level truncation of tensor product coefficients expected
+to be sufficient for the evaluation of fusion coefficients. We reformulate the
+depth rule in a precise way, and show how, in principle, it can be used to
+calculate fusion coefficients. However, we argue that the computation of the
+depth itself, in terms of which the constraints on tensor product coefficients
+is formulated, is problematic. Indeed, the elements of the basis of states
+convenient for calculating tensor product coefficients do not have a
+well-defined depth! We proceed by showing how one can calculate the depth in an
+`approximate' way and derive accurate lower bounds for the minimum level at
+which a coupling appears. It turns out that this method yields exact results
+for $\widehat{su}(3)$ and constitutes an efficient and simple algorithm for
+computing $\widehat{su}(3)$ fusion coefficients.",9203004v2
+2004-04-21,Li Coefficients for Automorphic L-Functions,"Xian-Jin Li gave a criterion for the Riemann hypothesis in terms of the
+positivity of a set of coefficients lambda_n, indexed by the integers. We
+define similar coefficients attached to principal automorphic L-functions over
+GL(N). We relate these coefficients to values of Weil's quadratic functional
+for the associated automorphic representation, and deduce a Riemann hypothesis
+criterion in terms of positivity of the real parts of these coefficients. We
+determine asymptotics of the coefficients, both unconditionally and on the
+Riemann hypothesis, as n increases. We show the existence of an entire function
+of exponential type that interpolates the generalized Li coefficients at
+integer values.",0404394v4
+2007-08-25,Quiver coefficients of Dynkin type,"We study the Grothendieck classes of quiver cycles, i.e. invariant closed
+subvarieties of the representation space of a quiver. For quivers without
+oriented loops we show that the class of a quiver cycle is determined by quiver
+coefficients, which generalize the earlier studied quiver coefficients for
+equioriented quivers of type A. We conjecture that quiver coefficients satisfy
+positivity and finiteness properties. Our main result is a formula for the
+quiver coefficients for orbit closures of Dynkin type with rational
+singularities, which confirms the finiteness conjecture. This formula is based
+on Reineke's desingularization of such orbit closures. For quivers of type A3,
+we give positive combinatorial formulas for the quiver coefficients, which
+confirm the full conjecture. We also interpret quiver coefficients as formulas
+for degeneracy loci defined by quivers of vector bundle maps.",0708.3418v1
+2009-03-23,Shear Viscosity to Entropy Density Ratio in Six Derivative Gravity,"We calculate shear viscosity to entropy density ratio in presence of four
+derivative (with coefficient $\alpha'$) and six derivative (with coefficient
+$\alpha'^2$) terms in bulk action. In general, there can be three possible four
+derivative terms and ten possible six derivative terms in the Lagrangian. Among
+them two four derivative and eight six derivative terms are ambiguous, i.e.,
+these terms can be removed from the action by suitable field redefinitions.
+Rest are unambiguous. According to the AdS/CFT correspondence all the
+unambiguous coefficients (coefficients of unambiguous terms) can be fixed in
+terms of field theory parameters. Therefore, any measurable quantities of
+boundary theory, for example shear viscosity to entropy density ratio, when
+calculated holographically can be expressed in terms of unambiguous
+coefficients in the bulk theory (or equivalently in terms of boundary
+parameters). We calculate $\eta/s$ for generic six derivative gravity and find
+that apparently it depends on few ambiguous coefficients at order $\alpha'^2$.
+We calculate six derivative corrections to central charges $a$ and $c$ and
+express $\eta/s$ in terms of these central charges and unambiguous coefficients
+in the bulk theory.",0903.3925v2
+2009-05-25,"""Clumpiness"" Mixing in Complex Networks","Three measures of clumpiness of complex networks are introduced. The measures
+quantify how most central nodes of a network are clumped together. The
+assortativity coefficient defined in a previous study measures a similar
+characteristic, but accounts only for the clumpiness of the central nodes that
+are directly connected to each other. The clumpiness coefficient defined in the
+present paper also takes into account the cases where central nodes are
+separated by a few links. The definition is based on the node degrees and the
+distances between pairs of nodes. The clumpiness coefficient together with the
+assortativity coefficient can define four classes of network. Numerical
+calculations demonstrate that the classification scheme successfully
+categorizes 30 real-world networks into the four classes: clumped assortative,
+clumped disassortative, loose assortative and loose disassortative networks.
+The clumpiness coefficient also differentiates the Erdos-Renyi model from the
+Barabasi-Albert model, which the assortativity coefficient could not
+differentiate. In addition, the bounds of the clumpiness coefficient as well as
+the relationships between the three measures of clumpiness are discussed.",0905.4096v1
+2009-06-30,Construction of operator product expansion coefficients via consistency conditions,"In this thesis an iterative scheme for the construction of operator product
+expansion (OPE) coefficients is applied to determine low order coefficients in
+perturbation theory for a specific toy model. We use the approach to quantum
+field theory proposed by S. Hollands [arXiv:0802.2198], which is centered
+around the OPE and a number of axioms on the corresponding OPE coefficients.
+This framework is reviewed in the first part of the thesis.
+  In the second part we apply an algorithm for the perturbative construction of
+OPE coefficients to a toy model: Euclidean $\varphi^6$-theory in 3-dimensions.
+Using a recently found formulation in terms of vertex operators and a
+diagrammatic notation in terms of trees [arXiv:0906.5313v1], coefficients up to
+second order are constructed, some general features of coefficients at
+arbitrary order are presented and an exemplary comparison to the corresponding
+customary method of computation is given.",0906.5468v1
+2009-08-22,Generalization of Fibonomial Coefficients,"Following Lucas and then other Fibonacci people Kwasniewski had introduced
+and had started ten years ago the open investigation of the overall F-nomial
+coefficients which encompass among others Binomial, Gaussian and Fibonomial
+coefficients with a new unified combinatorial interpretation expressed in terms
+of cobweb posets' partitions and tilings of discrete hyperboxes. In this paper,
+we deal with special subfamily of T-nomial coefficients.
+  The main aim of this note is to develop the theory of T-nomial coefficients
+with the help of generating functions. The binomial-like theorem for T-nomials
+is delivered here and some consequences of it are drawn. A new combinatorial
+interpretation of T-nomial coefficients is provided and compared with the
+Konvalina way of objects' selections from weighted boxes. A brief summary of
+already known properties of T-nomial coefficients is served.",0908.3248v1
+2010-01-02,"A note on dilation coefficient, plane-width, and resolution coefficient of graphs","In this note we study and compare three graph invariants related to the
+'compactness' of graph drawing in the plane: the dilation coefficient, defined
+as the smallest possible quotient between the longest and the shortest edge
+length; the plane-width, which is the smallest possible quotient between the
+largest distance between any two points and the shortest length of an edge; and
+the resolution coefficient, the smallest possible quotient between the longest
+edge length and the smallest distance between any two points. These three
+invariants coincide for complete graphs.
+  We show that graphs with large dilation coefficient or plane-width have a
+vertex with large valence but there exist cubic graphs with arbitrarily large
+resolution coefficient. Surprisingly enough, the one-dimensional analogues of
+these three invariants allow us to revisit the three well known graph
+parameters: the circular chromatic number, the chromatic number, and the
+bandwidth. We also examine the connection between bounded resolution
+coefficient and minor-closed graph classes.",1001.0330v1
+2010-05-25,Measuring small absorptions exploiting photo-thermal self-phase modulation,"We present a method for the measurement of small optical absorption
+coefficients. The method exploits the deformation of cavity Airy peaks that
+occur if the cavity contains an absorbing material with a non-zero
+thermo-refractive coefficient dn/dT or a non-zero expansion coefficient ath .
+Light absorption leads to a local temperature change and to an
+intensity-dependent phase shift, i.e. to a photo-thermal self-phase modulation.
+The absorption coefficient is derived from a comparison of time-resolved
+measurements with a numerical time-domain simulation applying a Markov-chain
+Monte-Carlo (MCMC) algorithm. We apply our method to the absorption coefficient
+of lithium niobate (LN) doped with 7mol% magnesium oxide (MgO) and derive a
+value of alphaLN = (5.9 +/- 0.9) *10^-4/cm . Our method should also apply to
+materials with much lower absorption coefficients. Based on our modelling we
+estimate that with cavity finesse values of the order 10^4, absorption
+coefficients of as low as 10^-8 /cm can be measured.",1005.4490v1
+2010-07-05,Fusion of Daubechies Wavelet Coefficients for Human Face Recognition,"In this paper fusion of visual and thermal images in wavelet transformed
+domain has been presented. Here, Daubechies wavelet transform, called as D2,
+coefficients from visual and corresponding coefficients computed in the same
+manner from thermal images are combined to get fused coefficients. After
+decomposition up to fifth level (Level 5) fusion of coefficients is done.
+Inverse Daubechies wavelet transform of those coefficients gives us fused face
+images. The main advantage of using wavelet transform is that it is well-suited
+to manage different image resolution and allows the image decomposition in
+different kinds of coefficients, while preserving the image information. Fused
+images thus found are passed through Principal Component Analysis (PCA) for
+reduction of dimensions and then those reduced fused images are classified
+using a multi-layer perceptron. For experiments IRIS Thermal/Visual Face
+Database was used. Experimental results show that the performance of the
+approach presented here achieves maximum success rate of 100% in many cases.",1007.0621v1
+2010-12-08,Littlewood-Richardson coefficients for reflection groups,"In this paper we explicitly compute all Littlewood-Richardson coefficients
+for semisimple or Kac-Moody groups G, that is, the structure coefficients of
+the cohomology algebra H^*(G/P), where P is a parabolic subgroup of G. These
+coefficients are of importance in enumerative geometry, algebraic combinatorics
+and representation theory. Our formula for the Littlewood-Richardson
+coefficients is given in terms of the Cartan matrix and the Weyl group of G.
+However, if some off-diagonal entries of the Cartan matrix are 0 or -1, the
+formula may contain negative summands. On the other hand, if the Cartan matrix
+satisfies $a_{ij}a_{ji}\ge 4$ for all $i,j$, then each summand in our formula
+is nonnegative that implies nonnegativity of all Littlewood-Richardson
+coefficients. We extend this and other results to the structure coefficients of
+the T-equivariant cohomology of flag varieties G/P and Bott-Samelson varieties
+Gamma_\ii(G).",1012.1714v5
+2012-06-08,Spin-dependent Seebeck coefficients of Ni_{80}Fe_{20} and Co in nanopillar spin valves,"We have experimentally determined the spin-dependent Seebeck coefficient of
+permalloy (Ni_{80}Fe_{20}) and cobalt (Co) using nanopillar spin valve devices.
+The devices were specifically designed to completely separate heat related
+effects from charge related effects. A pure heat current through the nanopillar
+spin valve, a stack of two ferromagnetic layers (F) separated by a non-magnetic
+layer (N), leads to a thermovoltage proportional to the spin-dependent Seebeck
+coefficient S_{S}=S_{\uparrow}-S_{\downarrow} of the ferromagnet, where
+S_{\uparrow} and S_{\downarrow} are the Seebeck coefficient for spin-up and
+spin-down electrons. By using a three-dimensional finite-element model (3D-FEM)
+based on spin-dependent thermoelectric theory, whose input material parameters
+were measured in separate devices, we were able to accurately determine a
+spin-dependent Seebeck coefficient of -1.8 microvolt/Kelvin and -4.5
+microvolt/Kelvin for cobalt and permalloy, respectively corresponding to a
+Seebeck coefficient polarization P_{S}=S_{S}/S_{F} of 0.08 and 0.25, where
+S_{F} is the Seebeck coefficient of the ferromagnet. The results are in
+agreement with earlier theoretical work in Co/Cu multilayers and spin-dependent
+Seebeck and spin-dependent Peltier measurements in Ni_{80}Fe_{20}/Cu spin valve
+structures.",1206.1659v1
+2012-09-07,Recovering Missing Coefficients in DCT-Transformed Images,"A general method for recovering missing DCT coefficients in DCT-transformed
+images is presented in this work. We model the DCT coefficients recovery
+problem as an optimization problem and recover all missing DCT coefficients via
+linear programming. The visual quality of the recovered image gradually
+decreases as the number of missing DCT coefficients increases. For some images,
+the quality is surprisingly good even when more than 10 most significant DCT
+coefficients are missing. When only the DC coefficient is missing, the proposed
+algorithm outperforms existing methods according to experimental results
+conducted on 200 test images. The proposed recovery method can be used for
+cryptanalysis of DCT based selective encryption schemes and other applications.",1209.1673v1
+2013-07-28,Measures of dependence between random vectors and tests of independence. Literature review,"Simple correlation coefficients between two variables have been generalized
+to measure association between two matrices in many ways. Coefficients such as
+the RV coefficient, the distance covariance (dCov) coefficient and kernel based
+coefficients have been adopted by different research communities. Scientists
+use these coefficients to test whether two random vectors are linked. If they
+are, it is important to uncover what patterns exist in these associations.
+  We discuss the topic of measures of dependence between random vectors and
+tests of independence and show links between different approaches. We document
+some of the interesting rediscoveries and lack of interconnection between
+bodies of literature. After providing definitions of the coefficients and
+associated tests, we present the recent improvements that enhance their
+statistical properties and ease of interpretation. We summarize multi-table
+approaches and provide scenarii where the indices can provide useful summaries
+of heterogeneous multi-block data.
+  We illustrate these different strategies on several examples of real data and
+suggest directions for future research.",1307.7383v3
+2013-10-23,The Concept of Heterogeneous Scattering Coefficients and Its Application in Inverse Medium Scattering,"This work investigates the scattering coefficients for inverse medium
+scattering problems. It shows some fundamental properties of the coefficients
+such as symmetry and tensorial properties. The relationship between the
+scattering coefficients and the far-field pattern is also derived. Furthermore,
+the sensitivity of the scattering coefficients with respect to changes in the
+permittivity and permeability distributions is investigated. In the linearized
+case, explicit formulas for reconstructing permittivity and permeability
+distributions from the scattering coefficients is proposed. They relate the
+exponentially ill-posed character of the inverse medium scattering problem at a
+fixed frequency to the exponential decay of the scattering coefficients.
+Moreover, they show the stability of the reconstruction from multifrequency
+measurements. This provides a new direction for solving inverse medium
+scattering problems.",1310.6096v1
+2014-01-25,Relativistic many-body calculations of van der Waals coefficients for Yb-Li and Yb-Rb dimers,"We derive the relativistic formulas for the van der Waals coefficients of
+Yb-alkali dimers that correlate to ground and excited separated-atom limits. We
+calculate $C_6$ and $C_8$ coefficients of particular experimental interest. We
+also derive a semi-empirical formula that expresses the $C_8$ coefficient of
+heteronuclear $A+B$ dimers in terms of the $C_6$ and $C_8$ coefficients of
+homonuclear dimers and the static dipole and quadrupole polarizabilities of the
+atomic states $A$ and $B$. We report results of calculation of the $C_6$
+coefficients for the Yb-Rb $^3/!P_1^o+5s\, ^2/!S_{1/2}$ and $^1/!S_0+5p\,
+^2/!P^o_{1/2}$ dimers, and the $C_8$ coefficients for the Yb-Li $^1/!S_0+2s\,
+^2/!S_{1/2}$ and Yb-Rb $^1/!S_0+5s\, ^2/!S_{1/2}$ dimers. Uncertainties are
+estimated for all predicted properties.",1401.6585v1
+2014-07-01,"Polynomial Interpretations over the Natural, Rational and Real Numbers Revisited","Polynomial interpretations are a useful technique for proving termination of
+term rewrite systems. They come in various flavors: polynomial interpretations
+with real, rational and integer coefficients. As to their relationship with
+respect to termination proving power, Lucas managed to prove in 2006 that there
+are rewrite systems that can be shown polynomially terminating by polynomial
+interpretations with real (algebraic) coefficients, but cannot be shown
+polynomially terminating using polynomials with rational coefficients only. He
+also proved the corresponding statement regarding the use of rational
+coefficients versus integer coefficients. In this article we extend these
+results, thereby giving the full picture of the relationship between the
+aforementioned variants of polynomial interpretations. In particular, we show
+that polynomial interpretations with real or rational coefficients do not
+subsume polynomial interpretations with integer coefficients. Our results hold
+also for incremental termination proofs with polynomial interpretations.",1407.0406v2
+2014-09-03,Reduction of the resonance error in numerical homogenisation II: correctors and extrapolation,"This paper is the companion article of [Gloria, M3AS, 21 (2011), No. 3, pp
+1601-1630]. One common drawback among numerical homogenization methods is the
+presence of the so-called resonance error, which roughly speaking is a function
+of the ratio $\frac{\varepsilon}{\rho}$, where $\rho$ is a typical macroscopic
+lengthscale and $\varepsilon$ is the typical size of the heterogeneities. In
+the present work, we make a systematic use of regularization and extrapolation
+to reduce this resonance error at the level of the approximation of homogenized
+coefficients and correctors for general non-necessarily symmetric stationary
+ergodic coefficients. We quantify this reduction for the class of periodic
+coefficients, for the Kozlov subclass of almost periodic coefficients, and for
+the subclass of random coefficients that satisfy a spectral gap estimate (e.g.
+Poisson random inclusions). We also report on a systematic numerical study in
+dimension 2, which demonstrates the efficiency of the method and the sharpness
+of the analysis. Last, we combine this approach to numerical homogenization
+methods, prove the asymptotic consistency in the case of locally stationary
+ergodic coefficients and give quantitative estimates in the case of periodic
+coefficients.",1409.1155v1
+2014-11-20,Local Adaptive Grouped Regularization and its Oracle Properties for Varying Coefficient Regression,"Varying coefficient regression is a flexible technique for modeling data
+where the coefficients are functions of some effect-modifying parameter, often
+time or location in a certain domain. While there are a number of methods for
+variable selection in a varying coefficient regression model, the existing
+methods are mostly for global selection, which includes or excludes each
+covariate over the entire domain. Presented here is a new local adaptive
+grouped regularization (LAGR) method for local variable selection in spatially
+varying coefficient linear and generalized linear regression. LAGR selects the
+covariates that are associated with the response at any point in space, and
+simultaneously estimates the coefficients of those covariates by tailoring the
+adaptive group Lasso toward a local regression model with locally linear
+coefficient estimates. Oracle properties of the proposed method are established
+under local linear regression and local generalized linear regression. The
+finite sample properties of LAGR are assessed in a simulation study and for
+illustration, the Boston housing price data set is analyzed.",1411.5725v1
+2015-04-13,Cohomology with twisted coefficients of the classifying space of a fusion system,"We study the cohomology with twisted coefficients of the geometric
+realization of a linking system associated to a saturated fusion system
+$\mathcal{F}$. More precisely, we extend a result due to Broto, Levi and Oliver
+to twisted coefficients. We generalize the notion of $\mathcal{F}$-stable
+elements to $\mathcal{F}^c$-stable elements in a setting of cohomology with
+twisted coefficients by an action of the fundamental group.% or, in other word,
+with locally constant coefficients. We then study the problem of inducing an
+idempotent from an $\mathcal{F}$-characteristic $(S,S)$-biset and we show that,
+if the coefficient module is nilpotent, then the cohomology of the geometric
+realization of a linking system can be computed by $\mathcal{F}^c$-stable
+elements. As a corollary, we show that for any coefficient module, the
+cohomology of the classifying space of a $p$-local finite group can be computed
+by these $\mathcal{F}^c$-stable elements.",1504.03191v4
+2015-12-11,Rectangular Kronecker coefficients and plethysms in geometric complexity theory,"We prove that in the geometric complexity theory program the vanishing of
+rectangular Kronecker coefficients cannot be used to prove superpolynomial
+determinantal complexity lower bounds for the permanent polynomial.
+  Moreover, we prove the positivity of rectangular Kronecker coefficients for a
+large class of partitions where the side lengths of the rectangle are at least
+quadratic in the length of the partition. We also compare rectangular Kronecker
+coefficients with their corresponding plethysm coefficients, which leads to a
+new lower bound for rectangular Kronecker coefficients. Moreover, we prove that
+the saturation of the rectangular Kronecker semigroup is trivial, we show that
+the rectangular Kronecker positivity stretching factor is 2 for a long first
+row, and we completely classify the positivity of rectangular limit Kronecker
+coefficients that were introduced by Manivel in 2011.",1512.03798v2
+2016-01-28,Virial coefficients from unified statistical thermodynamics of quantum gases trapped under generic power law potential in $d$ dimension and the equivalence of trapped quantum gases,"From the unified statistical thermodynamics of quantum gases, the virial
+coefficients of ideal Bose and Fermi gases which are trapped under generic
+power law potential are derived systematically. From the general result of
+virial coefficients, one can produce the known results in $d=3$ and $d=2$. But
+more importantly we found that, the virial coefficients of bosons and fermions
+become equal (except the the second virial coefficient, where the sign is
+different) when we trap the gases under harmonic potential in $d=1$. This
+result suggests the equivalence between Bose and Fermi gases which is already
+established for $d=1$ by M M Faruk (J Stat Phys, DOI
+10.1007/s10955-015-1344-4). Surprisingly our investigation also shows that the
+virial coefficients of two dimensional free quantum gases are identical to the
+virial coefficients of one dimensional harmonically trapped quantum gases.",1601.07946v2
+2016-06-22,A Moran coefficient-based mixed effects approach to investigate spatially varying relationships,"This study develops a spatially varying coefficient model by extending the
+random effects eigenvector spatial filtering model. The developed model has the
+following properties: its coefficients are interpretable in terms of the Moran
+coefficient; each of its coefficients can have a different degree of spatial
+smoothness; and it yields a variant of a Bayesian spatially varying coefficient
+model. Also, parameter estimation of the model can be executed with a
+relatively small computationally burden. Results of a Monte Carlo simulation
+reveal that our model outperforms a conventional eigenvector spatial filtering
+(ESF) model and geographically weighted regression (GWR) models in terms of the
+accuracy of the coefficient estimates and computational time. We empirically
+apply our model to the hedonic land price analysis of flood risk in Japan.",1606.06885v2
+2016-09-06,Stochastic homogenization of linear elliptic equations: Higher-order error estimates in weak norms via second-order correctors,"We are concerned with the homogenization of second-order linear elliptic
+equations with random coefficient fields. For symmetric coefficient fields with
+only short-range correlations, quantified through a logarithmic Sobolev
+inequality for the ensemble, we prove that when measured in weak spatial norms,
+the solution to the homogenized equation provides a higher-order approximation
+of the solution to the equation with oscillating coefficients. In the case of
+nonsymmetric coefficient fields, we provide a higher-order approximation (in
+weak spatial norms) of the solution to the equation with oscillating
+coefficients in terms of solutions to constant-coefficient equations. In both
+settings, we also provide optimal error estimates for the two-scale expansion
+truncated at second order. Our results rely on novel estimates on the
+second-order homogenization corrector, which we establish via sensitivity
+estimates for the second-order corrector and a large-scale $L^p$ theory for
+elliptic equations with random coefficients. Our results also cover the case of
+elliptic systems.",1609.01528v2
+2016-10-27,Influence of multiorbitals and anisotropic Coulomb interactions on isotope effect coefficient in doped Fe-based superconductors,"The present work describes the theoretical analysis of isotope effect
+coefficient as a function of transition temperature in two orbital per site
+model Hamiltonian in iron based superconducting system. The expression of
+isotope effect coefficient has been computed numerically and self-consistently
+by employing Green's function technique within the BCS-mean-field
+approximation. It is observed that the isotope effect coefficient increases
+with the increase of the hybridization while with the increase in Coulomb
+interaction it starts decreasing. On increasing the carrier density per site in
+two orbital per site iron pnictide system, isotope effect coefficient
+($\alpha$) exhibits large values (much higher than BCS limit) at lower
+temperatures. While in the underdoped case, isotope effect coefficient shows
+minimum value in superconducting states of the iron based systems. Furthermore,
+it has been found that the large value of the isotope effect coefficient is the
+indication of the fact that the contribution of phonon alone is inadequate as
+the origin of superconductivity in these systems. Finally, the obtained
+theoretical results have been compared with experimental and existing
+theoretical observations in iron based superconductors.",1610.08888v1
+2016-11-18,Large Values of the Clustering Coefficient,"A prominent parameter in the context of network analysis, originally proposed
+by Watts and Strogatz (Collective dynamics of `small-world' networks, Nature
+393 (1998) 440-442), is the clustering coefficient of a graph $G$. It is
+defined as the arithmetic mean of the clustering coefficients of its vertices,
+where the clustering coefficient of a vertex $u$ of $G$ is the relative density
+$m(G[N_G(u)])/{d_G(u)\choose 2}$ of its neighborhood if $d_G(u)$ is at least
+$2$, and $0$ otherwise. It is unknown which graphs maximize the clustering
+coefficient among all connected graphs of given order and size.
+  We determine the maximum clustering coefficients among all connected regular
+graphs of a given order, as well as among all connected subcubic graphs of a
+given order. In both cases, we characterize all extremal graphs. Furthermore,
+we determine the maximum increase of the clustering coefficient caused by
+adding a single edge.",1611.06135v1
+2017-10-24,Lower Error Bounds for Strong Approximation of Scalar SDEs with non-Lipschitzian Coefficients,"We study pathwise approximation of scalar stochastic differential equations
+at a single time point or globally in time by means of methods that are based
+on finitely many observations of the driving Brownian motion. We prove lower
+error bounds in terms of the average number of evaluations of the driving
+Brownian motion that hold for every such method under rather mild assumptions
+on the coefficients of the equation. The underlying simple idea of our analysis
+is as follows: the lower error bounds known for equations with coefficients
+that have sufficient regularity globally in space should still apply in the
+case of coefficients that have this regularity in space only locally, in a
+small neighborhood of the initial value. Our results apply to a huge variety of
+equations with coefficients that are not globally Lipschitz continuous in space
+including Cox-Ingersoll-Ross processes, equations with superlinearly growing
+coefficients, and equations with discontinuous coefficients. In many of these
+cases the resulting lower error bounds even turn out to be sharp.",1710.08707v1
+2018-02-13,A theoretical guideline for designing an effective adaptive particle swarm,"In this paper we theoretically investigate underlying assumptions that have
+been used for designing adaptive particle swarm optimization algorithms in the
+past years. We relate these assumptions to the movement patterns of particles
+controlled by coefficient values (inertia weight and acceleration coefficient)
+and introduce three factors, namely the autocorrelation of the particle
+positions, the average movement distance of the particle in each iteration, and
+the focus of the search, that describe these movement patterns. We show how
+these factors represent movement patterns of a particle within a swarm and how
+they are affected by particle coefficients (i.e., inertia weight and
+acceleration coefficients). We derive equations that provide exact coefficient
+values to guarantee achieving a desired movement pattern defined by these three
+factors within a swarm. We then relate these movements to the searching
+capability of particles and provide guideline for designing potentially
+successful adaptive methods to control coefficients in particle swarm. Finally,
+we propose a new simple time adaptive particle swarm and compare its results
+with previous adaptive particle swarm approaches. Our experiments show that the
+theoretical findings indeed provide a beneficial guideline for successful
+adaptation of the coefficients in the particle swarm optimization algorithm.",1802.04855v1
+2018-03-02,Stability and error analysis for the Helmholtz equation with variable coefficients,"We discuss the stability theory and numerical analysis of the Helmholtz
+equation with variable and possibly non-smooth or oscillatory coefficients.
+Using the unique continuation principle and the Fredholm alternative, we first
+give an existence-uniqueness result for this problem, which holds under rather
+general conditions on the coefficients and on the domain. Under additional
+assumptions, we derive estimates for the stability constant (i.e., the norm of
+the solution operator) in terms of the data (i.e. PDE coefficients and
+frequency), and we apply these estimates to obtain a new finite element error
+analysis for the Helmholtz equation which is valid at high frequency and with
+variable wave speed. The central role played by the stability constant in this
+theory leads us to investigate its behaviour with respect to coefficient
+variation in detail. We give, via a 1D analysis, an a priori bound with
+stability constant growing exponentially in the variance of the coefficients
+(wave speed and/or diffusion coefficient). Then, by means a family of analytic
+examples (supplemented by numerical experiments), we show that this estimate is
+sharp",1803.00966v2
+2018-05-06,Self-diffusion coefficient of the square-well fluid from molecular dynamics within the constant force approach,"We present a systematic study of the self-diffusion coefficient for a fluid
+of particles interacting via the square-well pair potential by means of
+molecular dynamics simulations in the canonical (N,V,T) ensemble. The discrete
+nature of the interaction potential is modeled through the constant force
+approximation and the self-diffusion coefficients is determined for several
+packing fractions at super critical thermodynamic states. The dependence of the
+self-diffusion coefficient with the potential range $\lambda$ is analyzed in
+the range of $1.1 \leq \lambda \leq 1.5 $. The obtained molecular dynamics
+simulations results are in agreement with the self-diffusion coefficient
+predicted with the Enskog method. Additionally, we soh that the diffusion
+coefficient is very sensitive to the potential range, $\lambda$, at low
+densities leading to a density dependence of this coefficient not shared with
+other macroscopic properties such as the equation of state. The constant force
+approximation used in this work to model the discrete pair potential has shown
+to be an excellent scheme to compute the transport properties using standar
+computer simulations. Finally, the simulation results presented here are
+resourceful to improving theoretical approaches, such as the Enskog method.",1805.02245v1
+2018-06-15,Parametric versus nonparametric: the fitness coefficient,"The fitness coefficient, introduced in this paper, results from a competition
+between parametric and nonparametric density estimators within the likelihood
+of the data. As illustrated on several real datasets, the fitness coefficient
+generally agrees with p-values but is easier to compute and interpret. Namely,
+the fitness coefficient can be interpreted as the proportion of data coming
+from the parametric model. Moreover, the fitness coefficient can be used to
+build a semiparamteric compromise which improves inference over the parametric
+and nonparametric approaches. From a theoretical perspective, the fitness
+coefficient is shown to converge in probability to one if the model is true and
+to zero if the model is false. From a practical perspective, the utility of the
+fitness coefficient is illustrated on real and simulated datasets.",1806.05830v1
+2018-09-22,On the performance of the Euler-Maruyama scheme for SDEs with discontinuous drift coefficient,"Recently a lot of effort has been invested to analyze the $L_p$-error of the
+Euler-Maruyama scheme in the case of stochastic differential equations (SDEs)
+with a drift coefficient that may have discontinuities in space. For scalar
+SDEs with a piecewise Lipschitz drift coefficient and a Lipschitz diffusion
+coefficient that is non-zero at the discontinuity points of the drift
+coefficient so far only an $L_p$-error rate of at least $1/(2p)-$ has been
+proven. In the present paper we show that under the latter conditions on the
+coefficients of the SDE the Euler-Maruyama scheme in fact achieves an
+$L_p$-error rate of at least $1/2$ for all $p\in [1,\infty)$ as in the case of
+SDEs with Lipschitz coefficients.",1809.08423v1
+2018-10-10,Numerical Evaluation of the Relativistic Magnetized Plasma Susceptibility Tensor and Faraday Rotation Coefficients,"Polarized models of relativistically hot astrophysical plasmas require
+transport coefficients as input: synchrotron absorption and emission
+coefficients in each of the four Stokes parameters, as well as three Faraday
+rotation coefficients. Approximations are known for all coefficients for a
+small set of electron distribution functions, such as the Maxwell-Juttner
+relativistic thermal distribution, and a general procedure has been obtained by
+Huang & Shcherbakov for an isotropic distribution function. Here we provide an
+alternative general procedure, with a full derivation, for calculating
+absorption and rotation coefficients for an arbitrary isotropic distribution
+function. Our method involves the computation of the full plasma susceptibility
+tensor, which in addition to absorption and rotation coefficients may be used
+to determine plasma modes and the dispersion relation. We implement the scheme
+in a publicly available library with a simple interface, thus allowing for easy
+incorporation into radiation transport codes. We also provide a comprehensive
+survey of the literature and comparison with earlier results.",1810.05530v1
+2018-10-26,Diving Body Shape Coefficient Setting Based on Moment of Inertia Analysis,"In the diving competition rules, FINA specifies the code of different diving
+movements and its difficulty coefficient. The rule simply relies on the
+complexity of the action to determine the difficulty. In the formulation of the
+diving difficulty coefficient, the athlete's body shape has not been fully
+considered, so it is difficult to fully guarantee the fairness of the diving
+competition. Based on the above problems, this paper analyzes the rules of the
+FINA's 10-meter platform diving difficulty coefficient, establishes the
+multi-rigid-body model of the human body, obtains the relationship between the
+moment of inertia and the completion time of the athletes to complete each
+diving action and the athlete's body shape, and determines the index to measure
+the athlete's body shape. The Lagrange Interpolation Polynomial is used to
+establish the functional relationship between the body shape correction
+coefficient and the body shape correction index, and the body shape correction
+coefficient corresponding to different body type athletes is determined
+accordingly. Finally, a new 10-meter platform diving difficulty coefficient
+scheme was developed.",1811.04750v2
+2019-02-26,Numerical approximations for the variable coefficient fractional diffusion equations with non-smooth data,"In this article we study the numerical approximation of a variable
+coefficient fractional diffusion equation. Using a change of variable, the
+variable coefficient fractional diffusion equation is transformed into a
+constant coefficient fractional diffusion equation of the same order. The
+transformed equation retains the desirable stability property of being an
+elliptic equation. A spectral approximation scheme is proposed and analyzed for
+the transformed equation, with error estimates for the approximated solution
+derived. An approximation to the unknown of the variable coefficient fractional
+diffusion equation is then obtained by post processing the computed
+approximation to the transformed equation. Error estimates are also presented
+for the approximation to the unknown of the variable coefficient equation with
+both smooth and non-smooth diffusivity coefficient and right-hand side. Three
+numerical experiments are given whose convergence results are in strong
+agreement with the theoretically derived estimates.",1902.10208v1
+2019-03-26,The current density and transport coefficients in the fully ionized plasma with q-distributions in nonextensive statistics,"We study the current density and transport coefficients in the fully ionized
+plasma with the q-distributions in nonextensive statistics and in strong
+magnetic field. By using the generalized Boltzmann transport equation in
+nonextensive statistics, we derive the current density and the expressions of
+the transport coefficients, including the conductivity, the thermoelectric
+coefficient, the Hall coefficient, and the Nernst coefficient. It is shown that
+these new transport coefficients has been generalized to the nonequilibrium
+complex plasmas with q-distributions in nonextensive statistics, which depend
+strongly on the q-parameters and when we take the limit q to 1, they perfectly
+return to those for the plasma based on a Maxwellian distribution.",1904.07066v2
+2019-05-20,Floquet Problem and Center Manifold Reduction for Ordinary Differential Operators with Periodic Coefficients in Hilbert Spaces,"A first order differential equation with a periodic operator coefficient
+acting in a pair of Hilbert spaces is considered. This setting models both
+elliptic equations with periodic coefficients in a cylinder and parabolic
+equations with time periodic coefficients. Our main results are a construction
+of a pointwise projector and a spectral splitting of the system into a finite
+dimensional system of ordinary differential equations with constant
+coefficients and an infinite dimensional part whose solutions have better
+properties in a certain sense. This complements the well-known asymptotic
+results for periodic hypoelliptic problems in cylinders (Kuchment) and for
+elliptic problems in quasicylinders (Nazarov).
+  As an application we give a center manifold reduction for a class of
+non-linear ordinary differential equations in Hilbert spaces with periodic
+coefficients. This result generalizes the known case with constant coefficients
+(Mielke).",1905.07890v2
+2019-09-12,Multi-rater delta: extending the delta nominal measure of agreement between two raters to many raters,"The need to measure the degree of agreement among R raters who independently
+classify n subjects within K nominal categories is frequent in many scientific
+areas. The most popular measures are Cohen's kappa (R = 2), Fleiss' kappa,
+Conger's kappa and Hubert's kappa (R $\geq$ 2) coefficients, which have several
+defects. In 2004, the delta coefficient was defined for the case of R = 2,
+which did not have the defects of Cohen's kappa coefficient. This article
+extends the coefficient delta from R = 2 raters to R $\geq$ 2. The coefficient
+multi-rater delta has the same advantages as the coefficient delta with regard
+to the type kappa coefficients: i) it is intuitive and easy to interpret,
+because it refers to the proportion of replies that are concordant and non
+random; ii) the summands which give its value allow the degree of agreement in
+each category to be measured accurately, with no need to be collapsed; and iii)
+it is not affected by the marginal imbalance.",1909.05575v2
+2019-11-26,Determining Ultra-low Absorption Coefficients of Organic Semiconductors from the Sub-bandgap Photovoltaic External Quantum Efficiency,"Energy states below the bandgap of a semiconductor, such as trap states or
+charge transfer states in organic donor acceptor blends, can contribute to
+light absorption. Due to their low number density or ultrasmall absorption
+cross-section, the absorption coefficient of these states is challenging to
+measure using conventional transmission reflection spectrophotometry. As an
+alternative, the external quantum efficiency (EQE) of photovoltaic devices is
+often used as a representative of the absorption coefficient, where the
+spectral line shape of the EQE is considered to follow the absorption
+coefficient of the active layer material. In this work, it is shown that the
+subbandgap EQE is subject to thickness dependent low finesse cavity
+interference effects within the device, making this assumption questionable. A
+better estimate for the absorption coefficient is obtained when EQE spectra
+corresponding to different active layer thicknesses are fitted simultaneously
+for one attenuation coefficient using an iterative transfer matrix method. The
+principle is demonstrated for two model acceptor-donor systems (PCE12ITIC and
+PBTTTPC71BM) and accurate subgap absorption coefficients are determined. This
+approach has particular relevance for both understanding sub-gap states and
+their utilization in organic optoelectronic devices.",1911.11485v1
+2020-02-12,On the Coefficients of $(\mathbb{Z}/p)^n$-Equivariant Ordinary Cohomology with Coefficients in $\mathbb{Z}/p$,"This note contains a generalization to $p>2$ of the authors' previous
+calculations of the coefficients of $(\mathbb{Z}/2)^n$-equivariant ordinary
+cohomology with coefficients in the constant $\mathbb{Z}/2$-Mackey functor. The
+algberaic results by S.Kriz allow us to calculate the coefficients of the
+geometric fixed point spectrum $\Phi^{(\mathbb{Z}/p)^n}H\mathbb{Z}/p$, and more
+generally, the $\mathbb{Z}$-graded coefficients of the localization of
+$H\mathbb{Z}/p_{(\mathbb{Z}/p)^n}$ by inverting any chosen set of embeddings
+$S^0\rightarrow S^{\alpha_i}$ where $\alpha_i$ are non-trivial irreducible
+representations. We also calculate the $RO(G)^+$-graded coefficients of
+$H\mathbb{Z}/p_{(\mathbb{Z}/p)^n}$, which means the cohomology of a point
+indexed by an actual (not virtual) representation. (This is the ""non-derived""
+part, which has a nice algebraic description.)",2002.05284v1
+2020-02-27,DC Hall coefficient of the strongly correlated Hubbard model,"The Hall coefficient is related to the effective carrier density and Fermi
+surface topology in noninteracting and weakly interacting systems. In strongly
+correlated systems, the relation between the Hall coefficient and
+single-particle properties is less clear. Clarifying this relation would give
+insight into the nature of transport in strongly correlated materials that lack
+well-formed quasiparticles. In this work, we investigate the DC Hall
+coefficient of the Hubbard model using determinant quantum Monte Carlo in
+conjunction with a recently developed expansion of magneto-transport
+coefficients in terms of thermodynamic susceptibilities. At leading order in
+the expansion, we observe a change of sign in the Hall coefficient as a
+function of temperature and interaction strength, which we relate to a change
+in the topology of the apparent Fermi surface. We also combine our Hall
+coefficient results with optical conductivity values to evaluate the Hall
+angle, as well as effective mobility and effective mass based on Drude theory
+of metals.",2002.12289v2
+2020-05-20,Balancing spatial and non-spatial variation in varying coefficient modeling: a remedy for spurious correlation,"This study discusses the importance of balancing spatial and non-spatial
+variation in spatial regression modeling. Unlike spatially varying coefficients
+(SVC) modeling, which is popular in spatial statistics, non-spatially varying
+coefficients (NVC) modeling has largely been unexplored in spatial fields.
+Nevertheless, as we will explain, consideration of non-spatial variation is
+needed not only to improve model accuracy but also to reduce spurious
+correlation among varying coefficients, which is a major problem in SVC
+modeling. We consider a Moran eigenvector approach modeling spatially and
+non-spatially varying coefficients (S&NVC). A Monte Carlo simulation experiment
+comparing our S&NVC model with existing SVC models suggests both modeling
+accuracy and computational efficiency for our approach. Beyond that, somewhat
+surprisingly, our approach identifies true and spurious correlations among
+coefficients nearly perfectly, even when usual SVC models suffer from severe
+spurious correlations. It implies that S&NVC model should be used even when the
+analysis purpose is modeling SVCs. Finally, our S&NVC model is employed to
+analyze a residential land price dataset. Its results suggest existence of both
+spatial and non-spatial variation in regression coefficients in practice. The
+S&NVC model is now implemented in the R package spmoran.",2005.09981v2
+2020-07-16,Viscosity of the magnetized strongly coupled one-component plasma,"The viscosity tensor of the magnetized one-component plasma, consisting of
+five independent shear viscosity coefficients, a bulk viscosity coefficient,
+and a cross coefficient, is computed using equilibrium molecular dynamics
+simulations and the Green-Kubo relations. A broad range of Coulomb coupling and
+magnetization strength conditions are studied. Magnetization is found to
+strongly influence the shear viscosity coefficients when the gyrofrequency
+exceeds the Coulomb collision frequency. Three regimes are identified as the
+Coulomb coupling strength and magnetization strength are varied. The Green-Kubo
+relations are used to separate kinetic and potential energy contributions to
+each viscosity coefficient, showing how each contribution depends upon the
+magnetization strength. The shear viscosity coefficient associated with the
+component of the stress tensor parallel to the magnetic field, and the two
+coefficients associated with the component perpendicular to the magnetic field,
+are all found to merge to a common value at strong Coulomb coupling.",2007.08417v1
+2021-03-08,The Efficacy of the Method of Four Coefficients to Determine Charge Carrier Scattering,"The investigation of the electronic properties of semiconductors is
+inherently challenging due to the ensemble averaging of fundamentals to
+transport measurements (i.e., resistivity, Hall, and Seebeck coefficient
+measurements). Here, we investigate the incorporation of a fourth measurement
+of electronic transport, the Nernst coefficient, into the analysis, termed the
+method of four-coefficients. This approach yields the Fermi level, effective
+mass, scattering exponent, and relaxation time. We begin with a review of the
+underlying mathematics and investigate the mapping between the four-dimensional
+material property and transport coefficient spaces. We then investigate how the
+traditional single parabolic band method yields a single, potentially incorrect
+point on the solution sub-space. This uncertainty can be resolved through
+Nernst coefficient measurements and we map the span of the ensuing sub-space.
+We conclude with an investigation of how sensitive the analysis of transport
+coefficients is to experimental error for different sample types.",2103.04569v1
+2021-07-27,Updated Magnetized Transport Coefficients: Impact on Laser-Plasmas with Self-Generated or Applied Magnetic Fields,"Errors in the Epperlein & Haines [PoF (1986)] transport coefficients were
+recently found at low electron magnetizations, with new magnetic transport
+coefficients proposed simultaneously by two teams [Sadler, Walsh & Li, PRL
+(2021) and Davies, Wen, Ji & Held, PoP (2021)]; these two separate sets of
+updated coefficients are shown in this paper to be in agreement. The importance
+of these new coefficients in laser-plasmas with either self-generated or
+applied magnetic fields is demonstrated. When an external magnetic field is
+applied, the cross-gradient-Nernst term twists the field structure; this
+twisting is reduced by the new coefficients in the low magnetization regime.
+For plasmas where only self-generated magnetic fields are present, the new
+coefficients are found to result in the magnetic field moving with the
+Righi-Leduc heat-flow, enhancing the impact of MHD. Simulations of Biermann
+Battery magnetic fields around ICF hot-spot perturbations are presented, with
+cross-gradient-Nernst transport increasing spike penetration.",2107.12988v1
+2021-09-13,The correlation coefficient between citation metrics and winning a Nobel or Abel Prize,"Computing such correlation coefficient would be straightforward had we had
+available the rankings given by the prize committee to all scientists in the
+pool. In reality we only have citation rankings for all scientists. This means,
+however, that we have the ordinal rankings of the prize winners with regard to
+citation metrics. I use maximum likelihood method to infer the most probable
+correlation coefficient to produce the observed pattern of ordinal ranks of the
+prize winners. I get the correlation coefficients of 0.47 and 0.59 between the
+composite citation indicator and getting Abel Prize and Fields Medal,
+respectively. The correlation coefficient between getting a Nobel Prize and the
+Q-factor is 0.65. These coefficients are of the same magnitude as the
+correlation coefficient between Elo ratings of the chess players and their
+popularity measured as numbers of webpages mentioning the players.",2109.06329v1
+2021-09-23,Scattering by finely-layered obstacles: frequency-explicit bounds and homogenization,"We consider the scalar Helmholtz equation with variable, discontinuous
+coefficients, modelling transmission of acoustic waves through an anisotropic
+penetrable obstacle. We first prove a well-posedness result and a
+frequency-explicit bound on the solution operator, with both valid for
+sufficiently-large frequency and for a class of coefficients that satisfy
+certain monotonicity conditions in one spatial direction, and are only assumed
+to be bounded (i.e., $L^\infty$) in the other spatial directions. This class of
+coefficients therefore includes coefficients modelling transmission by
+penetrable obstacles with a (potentially large) number of layers (in 2-d) or
+fibres (in 3-d). Importantly, the frequency-explicit bound holds uniformly for
+all coefficients in this class; this uniformity allows us to consider
+highly-oscillatory coefficients and study the limiting behaviour when the
+period of oscillations goes to zero. In particular, we bound the $H^1$ error
+committed by the first-order bulk correction to the homogenized transmission
+problem, with this bound explicit in both the period of oscillations of the
+coefficients and the frequency of the Helmholtz equation; to our knowledge,
+this is the first homogenization result for the Helmholtz equation that is
+explicit in these two quantities and valid without the assumption that the
+frequency is small.",2109.11267v2
+2021-11-16,Operator Growth and Symmetry-Resolved Coefficient Entropy in Quantum Maps,"Operator growth, or operator spreading, describes the process where a
+""simple"" operator acquires increasing complexity under the Heisenberg time
+evolution of a chaotic dynamics, therefore has been a key concept in the study
+of quantum chaos in both single-particle and many-body systems. An explicit way
+to quantify the complexity of an operator is the Shannon entropy of its
+operator coefficients over a chosen set of operator basis, dubbed ""coefficient
+entropy"". However, it remains unclear if the basis-dependency of the
+coefficient entropy may result in a false diagnosis of operator growth, or the
+lack thereof. In this paper, we examine the validity of coefficient entropy in
+the presence of hidden symmetries. Using the quantum cat map as an example, we
+show that under a generic choice of operator basis, the coefficient entropy
+fails to capture the suppression of operator growth caused by the symmetries.
+We further propose ""symmetry-resolved coefficient entropy"" as the proper
+diagnosis of operator complexity, which takes into account robust unknown
+symmetries, and demonstrate its effectiveness in the case of quantum cat map.",2111.08729v1
+2022-01-13,Towards a realistic evaluation of transport coefficients in non-equilibrium space plasmas,"Recent studies have outlined the interest for the evaluation of transport
+coefficients in space plasmas, where the observed velocity distributions of
+plasma particles are conditioned not only by the binary collisions, e.g., at
+low energies, but also by the energisation of particles from their interaction
+with wave turbulence and fluctuations, generating the suprathermal
+Kappa-distributed populations. This paper provides a first estimate of the main
+transport coefficients based on regularised Kappa distributions (RKDs), which,
+unlike standard Kappa distributions (SKDs), enable macroscopic parameterisation
+without mathematical divergences or physical inconsistencies. All transport
+coefficients derived here, i.e., the diffusion and mobility coefficients,
+electric conductivity, thermoelectric coefficient and thermal conductivity, are
+finite and well defined for all values of $\kappa > 0$. Moreover, for low
+values of $\kappa$ (i.e., below the SKD poles), the transport coefficients can
+be orders of magnitudes higher than the corresponding Maxwellian limits,
+meaning that significant underestimations can be made if suprathermal electrons
+are ignored.",2201.05157v1
+2022-03-02,Fourth cluster and virial coefficients of a unitary Fermi gas for an arbitrary mass ratio,"We calculate the fourth cluster coefficients of the homogeneous unitary spin
+1/2 Fermi gas as functions of the internal-state mass ratio, over intervals
+constrained by the 3- or 4-body Efimov effect. For this we use our 2016
+conjecture (validated for equal masses by Hou and Drut in 2020) in a
+numerically efficient formulation making the sum over angular momentum converge
+faster, which is crucial at large mass ratio. The mean cluster coefficient,
+relevant for equal chemical potentials, is not of constant sign and increases
+rapidly close to the Efimovian thresholds. We also get the fourth virial
+coefficients, which we find to be very poor indicators of interaction-induced
+4-body correlations. We obtain analytically for all $n$ the cluster
+coefficients of order $n$ + 1 for an infinity-mass impurity fermion, matching
+the conjecture for $n=3$. Finally, in a harmonic potential, we predict a
+non-monotonic behavior of the 3 + 1 cluster coefficient with trapping
+frequency, near mass ratios where this coefficient vanishes in the homogeneous
+case.",2203.00916v2
+2022-08-11,"Painlevé IV, Chazy II, and Asymptotics for Recurrence Coefficients of Semi-classical Laguerre Polynomials and Their Hankel Determinants","This paper studies the monic semi-classical Laguerre polynomials based on
+previous work by Boelen and Van Assche \cite{Boelen}, Filipuk et al.
+\cite{Filipuk} and Clarkson and Jordaan \cite{Clarkson}. Filipuk, Van Assche
+and Zhang proved that the diagonal recurrence coefficient $\alpha_n(t)$
+satisfies the fourth Painlev\'{e} equation. In this paper we show that the
+off-diagonal recurrence coefficient $\beta_n(t)$ fulfills the first member of
+Chazy II system. We also prove that the sub-leading coefficient of the monic
+semi-classical Laguerre polynomials satisfies both the continuous and discrete
+Jimbo-Miwa-Okamoto $\sigma$-form of Painlev\'{e} IV. By using Dyson's Coulomb
+fluid approach together with the discrete system for $\alpha_n(t)$ and
+$\beta_n(t)$, we obtain the large $n$ asymptotic expansions of the recurrence
+coefficients and the sub-leading coefficient. The large $n$ asymptotics of the
+associate Hankel determinant (including the constant term) is derived from its
+integral representation in terms of the sub-leading coefficient.",2208.05883v1
+2022-09-07,Greedy expansions with prescribed coefficients in Hilbert spaces for special classes of dictionaries,"Greedy expansions with prescribed coefficients have been introduced by V. N.
+Temlyakov in the frame of Banach spaces. The idea is to choose a sequence of
+fixed (real) coefficients $\{c_n\}_{n=1}^\infty$ and a fixed set of elements
+(dictionary) of the Banach space; then, under suitable conditions on the
+coefficients and the dictionary, it is possible to expand all the elements of
+the Banach space in series that contain only the fixed coefficients and the
+elements of the dictionary. In Hilbert spaces the convergence of greedy
+algorithm with prescribed coefficients is characterized, in the sense that
+there are necessary and sufficient conditions on the coefficients in order that
+the algorithm is convergent for all the dictionaries. This paper is concerned
+with the question if such conditions can be weakened for particular classes of
+spaces or dictionaries; we prove that this is the case for finite dimensional
+spaces, and for some classes of dictionaries related to orthonormal sequences
+in infinite dimensional spaces.",2209.03091v2
+2022-12-23,Domain Decomposition Methods for Elliptic Problems with High Contrast Coefficients Revisited,"In this paper, we revisit the nonoverlapping domain decomposition methods for
+solving elliptic problems with high contrast coefficients. Some interesting
+results are discovered. We find that the Dirichlet-Neumann algorithm and
+Robin-Robin algorithms may make full use of the ratio of coefficients.
+Actually, in the case of two subdomains, we show that their convergence rates
+are $O(\epsilon)$, if $\nu_1\ll\nu_2$, where $\epsilon = \nu_1/\nu_2$ and
+$\nu_1,\nu_2$ are coefficients of two subdomains. Moreover, in the case of many
+subdomains, the condition number bounds of Dirichlet-Neumann algorithm and
+Robin-Robin algorithm are $1+\epsilon(1+\log(H/h))^2$ and
+$C+\epsilon(1+\log(H/h))^2$, respectively, where $\epsilon$ may be a very small
+number in the high contrast coefficients case. Besides, the convergence
+behaviours of the Neumann-Neumann algorithm and Dirichlet-Dirichlet algorithm
+may be independent of coefficients while they could not benefit from the
+discontinuous coefficients. Numerical experiments are preformed to confirm our
+theoretical findings.",2212.12216v1
+2023-01-17,Numerical experiments on coefficients of instanton partition functions,"We analyze the coefficients of partition functions of Vafa-Witten theory for
+the complex projective plane $\mathbb{CP}^2$. We experimentally study the
+growth of the coefficients for gauge group $SU(2)$ and $SU(3)$, which are
+examples of mock modular forms of depth $1$ and 2 respectively. We also
+introduce the notion of ``mock cusp form'', and study an example of weight 3
+related to the $SU(3)$ partition function. Numerical experiments on the first
+200 coefficients suggest that the coefficients of a mock modular form of weight
+$k$ grow as the coefficients of a modular form of weight $k$, that is to say as
+$n^{k-1}$. On the other hand the coefficients of the mock cusp form appear to
+grow as $n^{3/2}$, which exceeds the growth of classical cusp forms of weight
+3. We provide bounds using saddle point analysis, which however largely exceed
+the experimental observation.",2301.06711v2
+2023-02-22,Quantum complexity of the Kronecker coefficients,"Whether or not the Kronecker coefficients of the symmetric group count some
+set of combinatorial objects is a longstanding open question. In this work we
+show that a given Kronecker coefficient is proportional to the rank of a
+projector that can be measured efficiently using a quantum computer. In other
+words a Kronecker coefficient counts the dimension of the vector space spanned
+by the accepting witnesses of a QMA verifier, where QMA is the quantum analogue
+of NP. This implies that approximating the Kronecker coefficients to within a
+given relative error is not harder than a certain natural class of quantum
+approximate counting problems that captures the complexity of estimating
+thermal properties of quantum many-body systems. A second consequence is that
+deciding positivity of Kronecker coefficients is contained in QMA,
+complementing a recent NP-hardness result of Ikenmeyer, Mulmuley and Walter. We
+obtain similar results for the related problem of approximating row sums of the
+character table of the symmetric group. Finally, we discuss an efficient
+quantum algorithm that approximates normalized Kronecker coefficients to
+inverse-polynomial additive error.",2302.11454v2
+2023-05-03,Combinatorial interpretations of binomial analogues of Fibonacci and q Fibonacci numbers,"The Fibonomial and Gaussian binomial coefficients are well known analogues of
+the binomial coefficients. A combinatorial interpretation for these analogues
+was first presented by Sagan and Savage in 2010. We introduce a slightly
+modified interpretation of Fibonomial coefficients. We also prove some
+identities involving Gaussian binomial coefficients. Recently Bergeron gave a
+similar interpretation of the q Fibonomial coefficients. Inspired from the
+model given by Bennett, they obtained a staircase model for the q Fibonomial
+coefficients as well. They have provided the proofs for the same using
+induction and bijective correspondence techniques. We establish a new model for
+q Fibonacci numbers using which we can give a non bijective proof to the
+staircase model. We apply this model to prove some identities of q Fibonacci
+numbers. Also we will demonstrate some identities related to the q Fibonomial
+coefficients using the staircase model.",2305.01838v1
+2023-07-21,Revisiting the gas-phase chemical rate coefficients at high temperatures in CLOUDY,"A two-body gas-phase reaction rate coefficient can be given by the usual
+Arrhenius-type formula which depends on temperature. The UMIST Database for
+Astrochemistry is a widely used database for reaction rate coefficients. They
+provide fittings for coefficients valid over a particular range of
+temperatures. The permissible upper-temperature limits vary over a wide range:
+from 100 K to 41000K. A wide range of temperatures occurs in nature; thus, it
+requires evaluating the rate coefficients at temperatures outside the range of
+validity. As a result, a simple extrapolation of the rate coefficients can lead
+to unphysically large values at high temperatures. These result in unrealistic
+predictions. Here we present a solution to prevent the gas-phase reaction
+coefficients from diverging at a very high temperature. We implement this into
+the spectral synthesis code CLOUDY which operates over a wide range of
+temperatures from CMB to 10$^{10}$ K subject to different astrophysical
+environments.",2308.02500v1
+2023-11-14,Clustering coefficients for networks with higher order interactions,"We introduce a clustering coefficient for nondirected and directed
+hypergraphs, which we call the quad clustering coefficient. We determine the
+average quad clustering coefficient and its distribution in real-world
+hypergraphs and compare its value with those of random hypergraphs drawn from
+the configuration model. We find that real-world hypergraphs exhibit a
+nonnegligible fraction of nodes with a maximal value of the quad clustering
+coefficient, while we do not find such nodes in random hypergraphs.
+Interestingly, these highly clustered nodes can have large degrees and can be
+incident to hyperedges of large cardinality. Moreover, highly clustered nodes
+are not observed in an analysis based on the pairwise clustering coefficient of
+the associated projected graph that has binary interactions, and hence higher
+order interactions are required to identify nodes with a large quad clustering
+coefficient.",2311.08563v2
+2023-11-18,Asymptotic distributions of the average clustering coefficient and its variant,"In network data analysis, summary statistics of a network can provide us with
+meaningful insight into the structure of the network. The average clustering
+coefficient is one of the most popular and widely used network statistics. In
+this paper, we investigate the asymptotic distributions of the average
+clustering coefficient and its variant of a heterogeneous Erd\""{o}s-R\'{e}nyi
+random graph. We show that the standardized average clustering coefficient
+converges in distribution to the standard normal distribution. Interestingly,
+the variance of the average clustering coefficient exhibits a phase transition
+phenomenon. The sum of weighted triangles is a variant of the average
+clustering coefficient. It is recently introduced to detect geometry in a
+network. We also derive the asymptotic distribution of the sum weighted
+triangles, which does not exhibit a phase transition phenomenon as the average
+clustering coefficient. This result signifies the difference between the two
+summary statistics.",2311.10979v1
+2024-03-04,Binomial Coefficients and Littlewood--Richardson Coefficients for Interpolation Polynomials,"Inhomogeneous versions of Jack and Macdonald polynomials, called
+interpolation polynomials, have been introduced by Knop--Sahi (type $A$) and
+Okounkov (type $BC$). In this paper, we study binomial coefficients and
+Littlewood--Richardson (LR) coefficients for these interpolation polynomials.
+We extend to type $BC$ the weighted sum formula for binomial coefficients due
+to the second author in type $A$, and obtain a new weighted sum formula for LR
+coefficients for both types $A$ and $BC$. We prove that binomial coefficients
+are positive and monotone using the weighted sum formula and the combinatorial
+formulas due to Okounkov. As an application, we show that the containment
+partial order can be characterized in terms of Schur positivity or Jack
+positivity. This result is in parallel with the work of
+Cuttler--Greene--Skandera, Sra and Khare--Tao, which characterize two other
+partial orders, majorization and weak majorization, in terms of evaluation
+positivity of Schur functions.",2403.02490v1
+2024-01-30,Multi-view Subspace Clustering via An Adaptive Consensus Graph Filter,"Multiview subspace clustering (MVSC) has attracted an increasing amount of
+attention in recent years. Most existing MVSC methods first collect
+complementary information from different views and consequently derive a
+consensus reconstruction coefficient matrix to indicate the subspace structure
+of a multi-view data set. In this paper, we initially assume the existence of a
+consensus reconstruction coefficient matrix and then use it to build a
+consensus graph filter. In each view, the filter is employed for smoothing the
+data and designing a regularizer for the reconstruction coefficient matrix.
+Finally, the obtained reconstruction coefficient matrices from different views
+are used to create constraints for the consensus reconstruction coefficient
+matrix. Therefore, in the proposed method, the consensus reconstruction
+coefficient matrix, the consensus graph filter, and the reconstruction
+coefficient matrices from different views are interdependent. We provide an
+optimization algorithm to obtain their optimal values. Extensive experiments on
+diverse multi-view data sets demonstrate that our approach outperforms some
+state-of-the-art methods.",2403.08787v1
+1994-06-27,Reverberation mapping of active galactic nuclei : The SOLA method for time-series inversion,"In this paper a new method is presented to find the transfer function of the
+broad-line region in active galactic nuclei. The subtractive optimally
+localized averages (SOLA) method is a modified version of the Backus-Gilbert
+method and is presented as an alternative to the more often used
+maximum-entropy method. The SOLA method has been developed for use in
+helioseismology. It has been applied to the solar oscillation frequency
+splitting data currently available to deduce the internal rotation rate of the
+sun. The original SOLA method is reformulated in the present paper to cope with
+the slightly different problem of inverting time series. We use simulations to
+test the viability of the method and apply the SOLA method to the real data of
+the Seyfert-1 galaxy NGC 5548. We investigate the effects of measurement errors
+and how the resolution of the TF critically depends upon both the sampling rate
+and the photometric accuracy of the data. A uuencoded compressed postscript
+file of the paper which includes the figures is available by anonymous ftp at
+ftp://solaris.astro.uu.se/pub/articles/atmos/frank/PijWan.uue",9406070v1
+1997-06-20,Rejection of the Binary Broad-Line Region Interpretation of Double-Peaked Emission Lines in Three Active Galactic Nuclei,"It has been suggested that the peculiar double-peaked Balmer lines of certain
+broad-line radio galaxies come from individual broad-line regions associated
+with the black holes of a supermassive binary. We continue to search for
+evidence of the radial velocity variations characteristic of a double-lined
+spectroscopic binary that are required in such a model. After spectroscopic
+monitoring of three suitable candidates (Arp 102B, 3C 390.3, and 3C 332)
+spanning two decades, we find no such long-term systematic changes in radial
+velocity. A trend noticed by Gaskell in one of the Balmer-line peaks of 3C
+390.3 before 1988 did not continue after that year, invalidating his inferred
+orbital period and mass. Instead, we find lower limits on the plausible orbital
+periods that would require the assumed supermassive binaries in all three
+objects to have total masses in excess of 10^10 solar masses. In the case of 3C
+390.3 the total binary mass must exceed 10^11 solar masses to satisfy
+additional observational constraints on the inclination angle. Such large
+binary black hole masses are difficult to reconcile with other observations and
+with theory. In addition, there are peculiar properties of the line profiles
+and flux ratios in these objects that are not explained by ordinary broad-line
+region cloud models. We therefore doubt that the double-peaked line profiles of
+the three objects arise in a pair of broad-line regions. Rather, they are much
+more likely to be intimately associated with a single black hole.",9706222v2
+1999-08-13,Infrared Spectroscopy of the High Redshift Radio Galaxy MRC~2025-218 and a Neighboring Extremely Red Galaxy,"This paper presents infrared spectra taken with the newly commissioned
+NIRSPEC spectrograph on the Keck Telescope of the High Redshift Radio Galaxy
+MRC 2025-218 (z=2.630) and an extremely red galaxy (R-K > 6 mag) 9'' away.
+These observations represent the deepest infrared spectra of a radio galaxy to
+date and have allowed for the detection of Hbeta, OIII (4959/5007), OI (6300),
+Halpha, NII (6548/6583) and SII (6716/6713). The Halpha emission is very broad
+(FWHM~6000 km/s) and strongly supports AGN unification models linking radio
+galaxies and quasars. The line ratios are most consistent with a partially
+obscured nuclear region and very high excitation. The OIII (5007) line is
+extended several arcseconds and shows high velocity clouds in the extended
+emission. The nucleus also appears spectrally double and we argue that the
+radio galaxy is undergoing a violent merger process. The red galaxy, by
+comparison, is very featureless even though we have a good continuum detection
+in the H and K bands. We suggest that this object is a foreground galaxy,
+probably at a redshift less than 1.5.",9908153v1
+2000-01-11,2 micron Spectroscopy within 0.3 arcseconds of SgrA*,"We present moderate (R~$\approx$~2,700) and high resolution
+(R~$\approx$~22,000) 2.0$-$2.4 \micron\ spectroscopy of the central 0.1 square
+arcseconds of the Galaxy obtained with NIRSPEC, the facility near-infrared
+spectrometer for the Keck II telescope. The composite spectra do not have any
+features attributable to the brightest stars in the central cluster, i.e.\
+after background subtraction, W$_{\rm ^{12}CO(2-0)}$~$<$~2~\AA. This stringent
+limit leads us to conclude that the majority, if not all, of the stars are
+hotter than typical red giants. Coupled with previously reported photometry, we
+conclude that the sources are likely OB main sequence stars. In addition, the
+continuum slope in the composite spectrum is bluer than that of a red giant and
+is similar to that of the nearby hot star, IRS16NW. It is unlikely that they
+are late-type giants stripped of their outer envelopes because such sources
+would be much fainter than those observed. Given their inferred youth
+($\tau_{\rm age}$~$<$~20~\Myr), we suggest the possibility that the stars have
+formed within 0.1 pc of the supermassive black hole. We find a newly-identified
+broad-line component (V$_{\rm FWHM}$ $\approx$ 1,000 \kms) to the 2.2178
+\micron\ [\ion{Fe}{3}] line located within a few arcseconds of Sgr~A$^*$. A
+similar component is not seen in the Br-$\gamma$ emission.",0001171v1
+2000-02-17,Discovery of an Obscured Broad Line Region in the High Redshift Radio Galaxy MRC 2025-218,"This paper presents infrared spectra taken with the newly commissioned
+NIRSPEC spectrograph on the Keck II Telescope of the High Redshift Radio Galaxy
+MRC 2025-218 (z=2.63) These observations represent the deepest infrared spectra
+of a radio galaxy to date and have allowed for the detection of Hbeta, [OIII]
+(4959/5007), [OI] (6300), Halpha, [NII] (6548/6583) and [SII] (6716/6713). The
+Halpha emission is very broad (FWHM = 9300 km/s) and luminous (2.6x10^44
+ergs/s) and it is very comparable to the line widths and strengths of radio
+loud quasars at the same redshift. This strongly supports AGN unification
+models linking radio galaxies and quasars, although we discuss some of the
+outstanding differences. The [OIII] (5007) line is extremely strong and has
+extended emission with large relative velocities to the nucleus. We also derive
+that if the extended emission is due to star formation, each knot has a star
+formation rate comparable to a Lyman Break Galaxy at the same redshift.",0002335v1
+2000-02-26,Hot Stars and Cool Clouds: The Photodissociation Region M16,"We present high-resolution spectroscopy and images of a photodissociation
+region (PDR) in M16 obtained during commissioning of NIRSPEC on the Keck II
+telescope. PDRs play a significant role in regulating star formation, and M16
+offers the opportunity to examine the physical processes of a PDR in detail. We
+simultaneously observe both the molecular and ionized phases of the PDR and
+resolve the spatial and kinematic differences between them. The most prominent
+regions of the PDR are viewed edge-on. Fluorescent emission from nearby stars
+is the primary excitation source, although collisions also preferentially
+populate the lowest vibrational levels of H2. Variations in density-sensitive
+emission line ratios demonstrate that the molecular cloud is clumpy, with an
+average density n = 3x10^5 cm^(-3). We measure the kinetic temperature of the
+molecular region directly and find T_H2 = 930 K. The observed density,
+temperature, and UV flux imply a photoelectric heating efficiency of 4%. In the
+ionized region, n_i=5x10^3 cm^(-3) and T_HII = 9500 K. In the brightest regions
+of the PDR, the recombination line widths include a non-thermal component,
+which we attribute to viewing geometry.",0002491v1
+2000-02-28,The Rest-Frame Optical Spectrum of MS 1512-cB58,"Moderate resolution, near-IR spectroscopy of MS1512-cB58 is presented,
+obtained during commissioning of the the Near IR Spectrometer (NIRSPEC) on the
+Keck II telescope. The strong lensing of this z=2.72 galaxy by the foreground
+cluster MS1512+36 makes it the best candidate for detailed study of the
+rest-frame optical properties of Lyman Break Galaxies.
+  A redshift of z=2.7290+/-0.0007 is inferred from the emission lines, in
+contrast to the z=2.7233 calculated from UV observations of interstellar
+absorption lines. Using the Balmer line ratios, we find an extinction of
+E(B-V)=0.27. Using the line strengths, we infer an SFR=620+/-18 Msun/yr
+(H_0=75, q_0=0.1, Lambda =0), a factor of 2 higher than that measured from
+narrow-band imaging observations of the galaxy, but a factor of almost 4 lower
+than the SFR inferred from the UV continuum luminosity. The width of the Balmer
+lines yields a mass of M_vir=1.2x10^10 Msun. We find that the oxygen abundance
+is 1/3 solar, in good agreement with other estimates of the metallicity.
+However, we infer a high nitrogen abundance, which may argue for the presence
+of an older stellar population.",0002508v1
+2000-03-06,The Sunyaev-Zel'dovich Effect in Abell 370,"We present interferometric measurements of the Sunyaev-Zel'dovich (SZ) effect
+towards the galaxy cluster Abell 370. These measurements, which directly probe
+the pressure of the cluster's gas, show the gas distribution to be strongly
+aspherical, as do the x-ray and gravitational lensing observations. We
+calculate the cluster's gas mass fraction in two ways. We first compare the gas
+mass derived from the SZ measurements to the lensing-derived gravitational mass
+near the critical lensing radius. We also calculate the gas mass fraction from
+the SZ data by deprojecting the three-dimensional gas density distribution and
+deriving the total mass under the assumption that the gas is in hydrostatic
+equilibrium (HSE). We test the assumptions in the HSE method by comparing the
+total cluster mass implied by the two methods and find that they agree within
+the errors of the measurement. We discuss the possible systematic errors in the
+gas mass fraction measurement and the constraints it places on the matter
+density parameter, OmegaM.",0003085v1
+2000-12-04,Galaxy Cluster Gas Mass Fractions from Sunyaev-Zel'dovich Effect Measurements: Constraints on Omega_M,"Using sensitive centimeter-wave receivers mounted on the Owens Valley Radio
+Observatory and Berkeley-Illinois-Maryland-Association millimeter arrays, we
+have obtained interferometric measurements of the Sunyaev-Zel'dovich (SZ)
+effect toward massive galaxy clusters. We use the SZ data to determine the
+pressure distribution of the cluster gas and, in combination with published
+X-ray temperatures, to infer the gas mass and total gravitational mass of 18
+clusters. The gas mass fraction, f_g, is calculated for each cluster, and is
+extrapolated to the fiducial radius r_{500} using the results of numerical
+simulations. The mean f_g within r_{500} is 0.081+0.009 -0.011/(h_{100}
+(statistical uncertainty at 68% confidence level, assuming OmegaM=0.3,
+OmegaL=0.7). We discuss possible sources of systematic errors in the mean f_g
+measurement. We derive an upper limit for OmegaM from this sample under the
+assumption that the mass composition of clusters within r_{500} reflects the
+universal mass composition: Omega_M h < Omega_B/f_g. The gas mass fractions
+depend on cosmology through the angular diameter distance and the r_{500}
+correction factors.
+  For a flat universe (OmegaL = 1 - OmegaM) and h=0.7, we find the measured gas
+mass fractions are consistent with Omegam less than 0.40, at 68% confidence.
+Including estimates of the baryons contained in galaxies and the baryons which
+failed to become bound during the cluster formation process, we find OmegaM
+\~0.25.",0012067v1
+2001-01-02,Science Prospects for SPI,"After the recent beautiful results on gamma-ray lines obtained with CGRO, the
+INTEGRAL mission with the imaging-spectrometer SPI will set the next milestone,
+combining improved sensitivity and angular resolution with a considerable
+increase in spectral resolution. SPI is expected to provide significant new
+information on galactic nucleosynthesis processes and star formation activity,
+as traced by the distributions of annihilation radiation and radioactive
+isotopes such as 26Al and 60Fe. The unprecedented spectral resolution will
+allow the study of dynamic processes in stellar mass ejections and will provide
+access to kinematic distance estimates for gamma-ray line sources. The study of
+supernovae and their remnants will be prime objectives for SPI observations.
+Nearby type Ia SN, within 15 Mpc or so, are in reach of the instrument and a
+few such events are expected during the lifetime of INTEGRAL. Young galactic
+supernova remnants, possibly hidden by interstellar dust, may be unveiled by
+their characteristic gamma-ray line signature from the radioactive decay of
+44Ti, as has been demonstrated by COMPTEL for Cas A and possibly RX
+J0852.0-4622. Classical novae are also among the SPI targets, which may observe
+the gamma-ray lines from radioactive 7Be and 22Na. Such observations can
+constrain the physics of the nova explosions and will allow to evaluate their
+role as nucleosynthesis sites. The interaction of cosmic rays with the dense
+matter in molecular clouds may be another source of gamma-ray lines that is
+potentially accessible to SPI. Finally after the SIGMA results on Nova Muscae
+and 1E1740.7-2942, and a possible 2.223 MeV line detection by COMPTEL, the
+search for lines from X novae is another way to participate in the
+understanding of the physical conditions in these close binary systems.",0101018v1
+2002-08-07,Massive Stars in the Arches Cluster,"We present and use new spectra and narrow-band images, along with previously
+published broad-band images, of stars in the Arches cluster to extract
+photometry, astrometry, equivalent width, and velocity information. The data
+are interpreted with a wind/atmosphere code to determine stellar temperatures,
+luminosities, mass-loss rates, and abundances. We have doubled the number of
+known emission-line stars, and we have also made the first spectroscopic
+identification of the main sequence for any population in the Galactic Center.
+We conclude that the most massive stars are bona-fide Wolf-Rayet (WR) stars and
+are some of the most massive stars known, having M_{initial} > 100 Msun, and
+prodigious winds, Mdot > 10^{-5} Msun yr^{-1}, that are enriched with helium
+and nitrogen; with these identifications, the Arches cluster contains about 5%
+of all known WR stars in the Galaxy. We find an upper limit to the velocity
+dispersion of 22 kms^{-1}, implying an upper limit to the cluster mass of
+7(10^4) Msun within a radius of 0.23 pc; we also estimate the bulk heliocentric
+velocity of the cluster to be v_{cluster,odot} approximately +95 kms^{-1}.",0208145v1
+2003-01-31,Ultraviolet spectroscopy of narrow coronal mass ejections,"We present Ultraviolet Coronagraph Spectrometer (UVCS) observations of 5
+narrow coronal mass ejections (CMEs) that were among 15 narrow CMEs originally
+selected by Gilbert et al. (2001). Two events (1999 March 27, April 15) were
+""structured"", i.e. in white light data they exhibited well defined interior
+features, and three (1999 May 9, May 21, June 3) were ""unstructured"", i.e.
+appeared featureless. In UVCS data the events were seen as 4-13 deg wide
+enhancements of the strongest coronal lines HI Ly-alpha and OVI (1032,1037 A).
+We derived electron densities for several of the events from the Large Angle
+Spectrometric Coronagraph (LASCO) C2 white light observations. They are
+comparable to or smaller than densities inferred for other CMEs. We modeled the
+observable properties of examples of the structured (1999 April 15) and
+unstructured (1999 May 9) narrow CMEs at different heights in the corona
+between 1.5 and 2 R(Sun). The derived electron temperatures, densities and
+outflow speeds are similar for those two types of ejections. They were compared
+with properties of polar coronal jets and other CMEs. We discuss different
+scenarios of narrow CME formation either as a jet formed by reconnection onto
+open field lines or CME ejected by expansion of closed field structures.
+Overall, we conclude that the existing observations do not definitively place
+the narrow CMEs into the jet or the CME picture, but the acceleration of the
+1999 April 15 event resembles acceleration seen in many CMEs, rather than
+constant speeds or deceleration observed in jets.",0301649v1
+2003-02-05,Cluster Sunyaev-Zeldovich Effect Scaling Relations,"X-ray observations of an ""entropy floor"" in nearby groups and clusters of
+galaxies offer evidence that important non-gravitational processes, such as
+radiative cooling and/or ""preheating"", have strongly influenced the evolution
+of the intracluster medium (ICM). We examine how the presence of an entropy
+floor modifies the thermal Sunyaev-Zeldovich (SZ) effect. A detailed analysis
+of scaling relations between X-ray and SZ effect observables and also between
+the two primary SZ effect observables is presented. We find that relationships
+between the central Compton parameter and the temperature or mass of a cluster
+are extremely sensitive to the presence of an entropy floor. The same is true
+for correlations between the integrated Compton parameter and the X-ray
+luminosity or the central Compton parameter. In fact, if the entropy floor is
+as high as inferred in recent analyses of X-ray data, a comparison of these
+correlations with both current and future SZ effect observations should show a
+clear signature of this excess entropy. Moreover, because the SZ effect is
+redshift-independent, the relations can potentially be used to track the
+evolution of the cluster gas and possibly discriminate between the possible
+sources of the excess entropy. To facilitate comparisons with observations, we
+provide analytic fits to these scaling relations.",0302087v1
+2003-03-20,"The SZ Effect Signature of Excess Entropy in Distant, Massive Clusters","Studies of cluster X-ray scaling relations have led to suggestions that
+non-gravitational processes, e.g., radiative cooling and/or ""preheating"", have
+significantly modified the entropy of the intracluster medium (ICM). For the
+first time, we test this hypothesis through a comparison of predicted thermal
+Sunyaev-Zeldovich (SZ) effect scaling relations with available data from the
+literature. One of the relations that we explore, in principle, depends solely
+on SZ effect observations, thus offering an X-ray independent probe of the ICM.
+A detailed comparison of the theoretical relations with the largest compilation
+of high redshift SZ effect data to date indicates that the presence of an
+entropy floor is favored by the data. Furthermore, the inferred level of that
+floor, 300 keV cm^2 or higher, is comparable to that found in studies of X-ray
+scaling relations of nearby massive clusters. Thus, we find no evidence for
+significant evolution of the entropy floor out to z = 0.7. We further
+demonstrate that the high quality data to be obtained from the upcoming
+Sunyaev-Zeldovich Array (SZA) and the (soon-to-be) upgraded Owens Valley Radio
+Observatory (OVRO) array will open powerful new windows into the properties of
+the ICM. Specifically, the new measurements will allow for accurate
+measurements of the ICM entropy for even the most distant galaxy clusters.",0303451v2
+2005-08-01,Transit Photometry of the Core-Dominated Planet HD 149026b,"We report g, V, and r photometric time series of HD 149026 spanning predicted
+times of transit of the Saturn-mass planetary companion, which was recently
+discovered by Sato and collaborators. We present a joint analysis of our
+observations and the previously reported photometry and radial velocities of
+the central star. We refine the estimate of the transit ephemeris to Tc [HJD] =
+2453527.87455^{+0.00085}_{-0.00091} + N * 2.87598^{+0.00012}_{-0.00017}.
+Assuming that the star has a radius of 1.45 +/- 0.10 R_Sun and a mass of 1.30
++/- 0.10 M_Sun, we estimate the planet radius to be 0.726 +/- 0.064 R_Jup,
+which implies a mean density of 1.07^{+0.42}_{-0.30} g/cm^3. This density is
+significantly greater than that predicted for models which include the effects
+of stellar insolation and for which the planet has only a small core of solid
+material. Thus we confirm that this planet likely contains a large core, and
+that the ratio of core mass to total planet mass is more akin to that of Uranus
+and Neptune than that of either Jupiter or Saturn.",0508051v1
+2005-10-28,Photoionized HBeta Emission in NGC 5548: It Breathes!,"Emission-line regions in active galactic nuclei and other photoionized
+nebulae should become larger in size when the ionizing luminosity increases.
+This 'breathing' effect is observed for the Hbeta emission in NGC 5548 by using
+Hbeta and optical continuum lightcurves from the 13-year 1989-2001 AGN Watch
+monitoring campaign. To model the breathing, we use two methods to fit the
+observed lightcurves in detail: (i) parameterized models and, (ii) the MEMECHO
+reverberation mapping code. Our models assume that optical continuum variations
+track the ionizing radiation, and that the Hbeta variations respond with time
+delays due to light travel time. By fitting the data using a delay map that is
+allowed to change with continuum flux, we find that the strength of the Hbeta
+response decreases and the time delay increases with ionizing luminosity. The
+parameterized breathing models allow the time delay and the Hbeta flux to
+depend on the continuum flux so that, the time delay is proportional to the
+continuum flux to the power beta, and the Hbeta flux is proportional to the
+continuum flux to the power alpha. Our fits give 0.1 < beta < 0.46 and 0.57 <
+alpha < 0.66. alpha is consistent with previous work by Gilbert and Peterson
+(2003) and Goad, Korista and Knigge (2004). Although we find beta to be flatter
+than previously determined by Peterson et al. (2002) using cross-correlation
+methods, it is closer to the predicted values from recent theoretical work by
+Korista and Goad (2004).",0510800v1
+2006-07-25,The Transit Light Curve (TLC) Project. I. Four Consecutive Transits of the Exoplanet XO-1b,"We present RIz photometry of four consecutive transits of the newly
+discovered exoplanet XO-1b. We improve upon the estimates of the transit
+parameters, finding the planetary radius to be R_P = 1.184 +0.028/-0.018
+R_Jupiter and the stellar radius to be R_S = 0.928 +0.018/-0.013 R_Sun,
+assuming a stellar mass of M_S = 1.00 +/- 0.03 M_Sun. The uncertainties in the
+planetary and stellar radii are dominated by the uncertainty in the stellar
+mass. These uncertainties increase by a factor of 2-3 if a more conservative
+uncertainty of 0.10 M_Sun is assumed for the stellar mass. Our estimate of the
+planetary radius is smaller than that reported by McCullough et al. (2006) and
+yields a mean density that is comparable to that of TrES-1 and HD 189733b. The
+timings of the transits have an accuracy ranging from 0.2 to 2.5 minutes, and
+are marginally consistent with a uniform period.",0607571v1
+2006-09-12,TrES-2: The First Transiting Planet in the Kepler Field,"We announce the discovery of the second transiting hot Jupiter discovered by
+the Trans-atlantic Exoplanet Survey. The planet, which we dub TrES-2, orbits
+the nearby star GSC 03549-02811 every 2.47063 days. From high-resolution
+spectra, we determine that the star has T_eff = 5960 +/- 100 K and log(g) = 4.4
++/- 0.2, implying a spectral type of G0V and a mass of 1.08 +0.11/-0.05 M_sun.
+High-precision radial-velocity measurements confirm a sinusoidal variation with
+the period and phase predicted by the photometry, and rule out the presence of
+line-bisector variations that would indicate that the spectroscopic orbit is
+spurious. We estimate a planetary mass of 1.28 +0.09/-0.04 M_Jup. We model B,
+r, R, and I photometric timeseries of the 1.4%-deep transits and find a
+planetary radius of 1.24 +0.09/-0.06 R_Jup. This planet lies within the field
+of view of the NASA Kepler mission, ensuring that hundreds of upcoming transits
+will be monitored with exquisite precision and permitting a host of
+unprecedented investigations.",0609335v1
+2006-10-19,Precise Radius Estimates for the Exoplanets WASP-1b and WASP-2b,"We present precise z-band photometric time series spanning times of transit
+of the two exoplanets recently discovered by the SuperWASP collaboration. We
+find planetary radii of 1.44 +/- 0.08 R_J and 1.04 +/- 0.06 R_J for WASP-1b and
+WASP-2b, respectively. These error estimates include both random errors in the
+photometry and also the uncertainty in the stellar masses. Our results are 5
+times more precise than the values derived from the discovery data alone. Our
+measurement of the radius of WASP-2b agrees with previously published models of
+hot Jupiters that include both a 20-M_Earth core of solid material and the
+effects of stellar insolation. In contrast, we find that the models cannot
+account for the large size of WASP-1b, even if the planet has no core. Thus, we
+add WASP-1b to the growing list of hot Jupiters that are larger than expected.
+This suggests that ``inflated'' hot Jupiters are more common than previously
+thought, and that any purported explanations involving highly unusual
+circumstances are disfavored.",0610589v1
+2007-02-16,The Extended Star Formation History of the Andromeda Spheroid at Twenty One Kiloparsecs on the Minor Axis,"Using the HST ACS, we have obtained deep optical images of a southeast
+minor-axis field in the Andromeda Galaxy, 21 kpc from the nucleus. In both star
+counts and metallicity, this field represents a transition zone between the
+metal-rich, highly-disturbed inner spheroid that dominates within 15 kpc and
+the metal-poor, diffuse population that dominates beyond 30 kpc. The
+color-magnitude diagram reaches well below the oldest main-sequence turnoff in
+the population, allowing a reconstruction of the star formation history in this
+field. Compared to the spheroid population at 11 kpc, the population at 21 kpc
+is ~1.3 Gyr older and ~0.2 dex more metal-poor, on average. However, like the
+population at 11 kpc, the population at 21 kpc exhibits an extended star
+formation history; one third of the stars are younger than 10 Gyr, although
+only a few percent are younger than 8 Gyr. The relatively wide range of
+metallicity and age is inconsistent with a single, rapid star-formation
+episode, and instead suggests that the spheroid even at 21 kpc is dominated by
+the debris of earlier merging events likely occurring more than 8 Gyr ago.",0702448v1
+2007-02-23,Discovery of Andromeda XIV: A Dwarf Spheroidal Dynamical Rogue in the Local Group?,"In the course of our survey of the outer halo of the Andromeda Galaxy we have
+discovered a remote, possible satellite of that system at a projected 162 kpc
+(11.7 degrees) radius. The fairly elongated (0.31 +/- 0.09 ellipticity) dwarf
+can be fit with a King profile of 1.07 kpc (d/784 kpc) limiting radius, where
+the satellite distance, d, is estimated at ~630-850 kpc from the tip of the red
+giant branch. The newfound galaxy, ``Andromeda XIV'' (``AndXIV''),
+distinguishes itself from other Local Group galaxies by its extreme dynamics:
+Keck/DEIMOS spectroscopy reveals it to have a large heliocentric radial
+velocity (-481 km/s), or -206 km/s velocity relative to M31. Even at its
+projected radius AndXIV already is at the M31 escape velocity based on the
+latest M31 mass models. If AndXIV is bound to M31, then recent models with
+reduced M31 virial masses need revision upward. If not bound to M31, then
+AndXIV is just now falling into the Local Group for the first time and
+represents a dwarf galaxy that formed and spent almost its entire life in
+isolation.",0702635v2
+1998-05-27,"Survival Analysis, Master Equation, Efficient Simulation of Path-Related Quantities, and Hidden State Concept of Transitions","This paper presents and derives the interrelations between survival analysis
+and master equation. Survival analysis deals with modeling the transitions
+between succeeding states of a system in terms of hazard rates. Questions
+related with this are the timing and sequencing of the states of a time series.
+The frequency and characteristics of time series can be investigated by
+Monte-Carlo simulations. If one is interested in cross-sectional data connected
+with the stochastic process under consideration, one needs to know the temporal
+evolution of the distribution of states. This can be obtained by simulation of
+the associated master equation. Some new formulas allow the determination of
+path-related (i.e. longitudinal) quantities like the occurence probability, the
+occurence time distribution, or the effective cumulative life-time distribution
+of a certain sequencing of states (path). These can be efficiently evaluated
+with a recently developed simulation tool (EPIS). The effective cumulative
+life-time distribution facilitates the formulation of a hidden state concept of
+behavioral changes which allows an interpretation of the respective
+time-dependence of hazard rates. Hidden states represent states which are
+either not phenomenological distinguishable from other states, not externally
+measurable, or simply not detected.",9805361v1
+1999-09-09,Micromagnetic simulations of thermally activated magnetization reversal of nanoscale magnets,"Numerical integration of a stochastic Landau-Lifshitz-Gilbert equation is
+used to study dynamic processes in single-domain nanoscale magnets at nonzero
+temperatures. Special attention is given to including thermal fluctuations as a
+Langevin term, and the Fast Multipole Method is used to calculate dipole-dipole
+interactions. It is feasible to simulate these dynamics on the nanosecond time
+scale for spatial discretizations that involve on the order of 10000 nodes
+using a desktop workstation. The nanoscale magnets considered here are single
+pillars with large aspect ratio. Hysteresis-loop simulations are employed to
+study the stable and metastable configurations of the magnetization. Each
+pillar has magnetic end caps. In a time-dependent field the magnetization of
+the pillars is observed to reverse via nucleation, propagation, and coalescence
+of the end caps. In particular, the end caps propagate into the magnet and meet
+near the middle. A relatively long-lived defect is formed when end caps with
+opposite vorticity meet. Fluctuations are more important in the reversal of the
+magnetization for fields weaker than the zero-temperature coercive field, where
+the reversal is thermally activated. In this case, the process must be
+described by its statistical properties, such as the distribution of switching
+times, averaged over a large number of independent thermal histories.",9909136v2
+2000-10-12,Thermal Magnetization Reversal in Arrays of Nanoparticles,"The results of large-scale simulations investigating the dynamics of
+magnetization reversal in arrays of single-domain nanomagnets after a rapid
+reversal of the applied field at nonzero temperature are presented. The
+numerical micromagnetic approach uses the Landau-Lifshitz-Gilbert equation
+including contributions from thermal fluctuations and long-range dipole-dipole
+demagnetizing effects implemented using a fast-multipole expansion. The
+individual model nanomagnets are 9 nm x 9 nm x 150 nm iron pillars similar to
+those fabricated on a surface with STM-assisted chemical vapor deposition [S.
+Wirth, et al., J. Appl. Phys {\bf 85}, 5249 (1999)]. Nanomagnets oriented
+perpendicular to the surface and spaced 300 nm apart in linear arrays are
+considered. The applied field is always oriented perpendicular to the surface.
+When the magnitude of the applied field is less than the coercive value, about
+2000 Oe for an individual nanomagnet, magnetization reversal in the nanomagnets
+can only occur by thermally activated processes. Even though the interaction
+from the dipole moment of neighboring magnets in this geometry is only about 1
+Oe, less than 1% of the coercive field, it can have a large impact on the
+switching dynamics. What determines the height of the free-energy barrier is
+the difference between the coercive and applied fields, and 1 Oe can be a
+significant fraction of that. The magnetic orientations of the neighbors are
+seen to change the behavior of the nanomagnets in the array significantly.",0010184v2
+2001-12-12,"High Magnetic Field NMR Studies of LiVGe$_2$O$_6$, a quasi 1-D Spin $S = 1$ System","We report $^{7}$Li pulsed NMR measurements in polycrystalline and single
+crystal samples of the quasi one-dimensional S=1 antiferromagnet
+LiVGe$_2$O$_6$, whose AF transition temperature is $T_{\text{N}}\simeq 24.5$ K.
+The field ($B_0$) and temperature ($T$) ranges covered were 9-44.5 T and
+1.7-300 K respectively. The measurements included NMR spectra, the spin-lattice
+relaxation rate ($T_1^{-1}$), and the spin-phase relaxation rate ($T_2^{-1}$),
+often as a function of the orientation of the field relative to the crystal
+axes. The spectra indicate an AF magnetic structure consistent with that
+obtained from neutron diffraction measurements, but with the moments aligned
+parallel to the c-axis. The spectra also provide the $T$-dependence of the AF
+order parameter and show that the transition is either second order or weakly
+first order. Both the spectra and the $T_1^{-1}$ data show that $B_0$ has at
+most a small effect on the alignment of the AF moment. There is no spin-flop
+transition up to 44.5 T. These features indicate a very large magnetic
+anisotropy energy in LiVGe$_2$O$_6$ with orbital degrees of freedom playing an
+important role. Below 8 K, $T_1^{-1}$ varies substantially with the orientation
+of $B_0$ in the plane perpendicular to the c-axis, suggesting a small energy
+gap for magnetic fluctuations that is very anisotropic.",0112203v1
+2003-10-07,Endogenous Versus Exogenous Shocks in Complex Networks: an Empirical Test Using Book Sale Ranking,"Are large biological extinctions such as the Cretaceous/Tertiary KT boundary
+due to a meteorite, extreme volcanic activity or self-organized critical
+extinction cascades? Are commercial successes due to a progressive reputation
+cascade or the result of a well orchestrated advertisement? Determining the
+chain of causality for extreme events in complex systems requires disentangling
+interwoven exogenous and endogenous contributions with either no clear or too
+many signatures. Here, we study the precursory and recovery signatures
+accompanying shocks, that we test on a unique database of the Amazon sales
+ranking of books. We find clear distinguishing signatures classifying two types
+of sales peaks. Exogenous peaks occur abruptly and are followed by a power law
+relaxation, while endogenous sale peaks occur after a progressively
+accelerating power law growth followed by an approximately symmetrical power
+law relaxation which is slower than for exogenous peaks. These results are
+rationalized quantitatively by a simple model of epidemic propagation of
+interactions with long memory within a network of acquaintances. The slow
+relaxation of sales implies that the sales dynamics is dominated by cascades
+rather than by the direct effects of news or advertisements, indicating that
+the social network is close to critical.",0310135v2
+2004-08-18,Irreversible spin-transfer and magnetization reversal under spin-injection,"In the context of spin electronics, the two spin-channel model assumes that
+the spin carriers are composed of two distinct populations: the conduction
+electrons of spin up, and the conduction electrons of spin down. In order to
+distinguish the paramagnetic and ferromagnetic contributions in spin injection,
+we describe the current injection with four channels : the two spin populations
+of the conduction bands ($s$ or paramagnetic) and the two spin populations of
+the more correlated electrons ($d$ or ferromagnetic). The redistribution of the
+conduction electrons at the interface is described by relaxation mechanisms
+between the channels. Providing that the $d$ majority-spin band is frozen,
+$s-d$ relaxation essentially concerns the minority-spin channels. Accordingly,
+even in the abscence of spin-flip scattering (i.e. without standard
+spin-accumulation or giant magnetoresistance), the $s-d$ relaxation leads to a
+$d$ spin accumulation effect. The coupled diffusion equations for the two
+relaxation processes ($s-d$ and spin-flip) are derived. The link with the
+ferromagnetic order parameter $\vec{M}$ is performed by assuming that only the
+$d$ channel contributes to the Landau-Lifshitz-Gilbert equation. The effect of
+magnetization reversal induced by spin injection is explained by these
+relaxations under the assumption that the spins of the conduction electrons act
+as environmental degrees of freedom on the magnetization.",0408410v1
+2004-12-02,Dielectric resonances in disordered media,"Binary disordered systems are usually obtained by mixing two ingredients in
+variable proportions: conductor and insulator, or conductor and
+super-conductor. and are naturally modeled by regular bi-dimensional or
+tri-dimensional lattices, on which sites or bonds are chosen randomly with
+given probabilities. In this article, we calculate the impedance of the
+composite by two independent methods: the so-called spectral method, which
+diagonalises Kirchhoff's Laws via a Green function formalism, and the Exact
+Numerical Renormalization method (ENR). These methods are applied to mixtures
+of resistors and capacitors (R-C systems), simulating e.g. ionic
+conductor-insulator systems, and to composites consituted of resistive
+inductances and capacitors (LR-C systems), representing metal inclusions in a
+dielectric bulk. The frequency dependent impedances of the latter composites
+present very intricate structures in the vicinity of the percolation threshold.
+We analyse the LR-C behavior of compounds formed by the inclusion of small
+conducting clusters (``$n$-legged animals'') in a dielectric medium. We
+investigate in particular their absorption spectra who present a pattern of
+sharp lines at very specific frequencies of the incident electromagnetic field,
+the goal being to identify the signature of each animal. This enables us to
+make suggestions of how to build compounds with specific absorption or
+transmission properties in a given frequency domain.",0412061v1
+2005-01-12,Current induced magnetization switching in exchange biased spin-valves for CPP-GMR heads,"In contrast to earlier studies performed on simple Co/Cu/Co sandwiches, we
+have investigated spin transfer effects in complex spin-valve pillars with a
+diameter of 130nm developed for current-perpendicular to the plane (CPP)
+magneto-resistive heads. The structure of the samples included an exchange
+biased synthetic pinned layer and a free layer both laminated by insertion of
+several ultrathin Cu layers. Despite the small thickness of the polarizing
+layer, our results show that the free layer can be switched between the
+parallel (P) and the antiparallel (AP) states by applying current densities of
+the order of 10^7 A/cm^2. A strong asymmetry is observed between the two
+critical currents IcAP-P and IcP-AP, as predicted by the model of Slonczewski
+model. Thanks to the use of exchange biased structures, the stability phase
+diagrams could be obtained in the four quadrants of the (H, I) plan. The
+critical lines derived from the magnetoresistance curves measured with
+different sense currents, and from the resistance versus current curves
+measured for different applied fields, match each other very well. The main
+features of the phase diagrams can be reproduced by investigating the stability
+of the solutions of the Landau Lifshitz Gilbert equation including spin torque
+term within a macrospin model. A spin-transfer saturation effect was observed
+in the positive currents range. We attribute it to a de-depolarization effect
+which appears as a consequence of the asymmetric heating of the pillars, whose
+top and the bottom leads are made of different materials.",0501281v1
+2005-12-20,Theory of Spin Torque in a nanomagnet,"We present a complete theory of the spin torque phenomena in a ultrasmall
+nanomagnet coupled to non-collinear ferromagnetic electrodes through tunnelling
+junctions. This model system can be described by a simple microscopic model
+which captures many physical effects characteristic of spintronics: tunneling
+magneto resistance, intrinsic and transport induced magnetic relaxation,
+current induced magnetization reversal and spin accumulation. Treating on the
+same footing the magnetic and transport degrees of freedom, we arrive at a
+closed equation for the time evolution of the magnetization. This equation is
+very close to the Landau-Lifshitz-Gilbert equation used in spin valves
+structures. We discuss how the presence of the Coulomb blockade phenomena and
+the discretization of the one-body spectrum gives some additional features to
+the current induced spin torque. Depending on the regime, the dynamic induced
+by the coupling to electrode can be viewed either as a spin torque or as a
+relaxation process. In addition to the possibility of stabilizing uniform spin
+precession states, we find that the system is highly hysteretic: up to three
+different magnetic states can be simultaneously stable in one region of the
+parameter space (magnetic field and bias voltage).We also discuss how the
+magneto-resistance can be used to provide additional information on the
+non-equilibrium peaks present in the nanomagnet spectroscopy experiments.",0512508v1
+2005-09-19,Capacity-Achieving Codes with Bounded Graphical Complexity on Noisy Channels,"We introduce a new family of concatenated codes with an outer low-density
+parity-check (LDPC) code and an inner low-density generator matrix (LDGM) code,
+and prove that these codes can achieve capacity under any memoryless
+binary-input output-symmetric (MBIOS) channel using maximum-likelihood (ML)
+decoding with bounded graphical complexity, i.e., the number of edges per
+information bit in their graphical representation is bounded. In particular, we
+also show that these codes can achieve capacity on the binary erasure channel
+(BEC) under belief propagation (BP) decoding with bounded decoding complexity
+per information bit per iteration for all erasure probabilities in (0, 1). By
+deriving and analyzing the average weight distribution (AWD) and the
+corresponding asymptotic growth rate of these codes with a rate-1 inner LDGM
+code, we also show that these codes achieve the Gilbert-Varshamov bound with
+asymptotically high probability. This result can be attributed to the presence
+of the inner rate-1 LDGM code, which is demonstrated to help eliminate high
+weight codewords in the LDPC code while maintaining a vanishingly small amount
+of low weight codewords.",0509062v3
+2006-07-20,List decoding of noisy Reed-Muller-like codes,"First- and second-order Reed-Muller (RM(1) and RM(2), respectively) codes are
+two fundamental error-correcting codes which arise in communication as well as
+in probabilistically-checkable proofs and learning. In this paper, we take the
+first steps toward extending the quick randomized decoding tools of RM(1) into
+the realm of quadratic binary and, equivalently, Z_4 codes. Our main
+algorithmic result is an extension of the RM(1) techniques from Goldreich-Levin
+and Kushilevitz-Mansour algorithms to the Hankel code, a code between RM(1) and
+RM(2). That is, given signal s of length N, we find a list that is a superset
+of all Hankel codewords phi with dot product to s at least (1/sqrt(k)) times
+the norm of s, in time polynomial in k and log(N). We also give a new and
+simple formulation of a known Kerdock code as a subcode of the Hankel code. As
+a corollary, we can list-decode Kerdock, too. Also, we get a quick algorithm
+for finding a sparse Kerdock approximation. That is, for k small compared with
+1/sqrt{N} and for epsilon > 0, we find, in time polynomial in (k
+log(N)/epsilon), a k-Kerdock-term approximation s~ to s with Euclidean error at
+most the factor (1+epsilon+O(k^2/sqrt{N})) times that of the best such
+approximation.",0607098v2
+1994-05-31,The Behavior of a Spherical Hole in an Infinite Uniform Universe,"In this paper, the behavior of a spherical hole in an otherwise infinite and
+uniform universe is investigated. First, the Newtonian theory is developed. The
+concept of negative gravity, an outward gravitational force acting away from
+the center of the spherical hole, is presented, and the resulting expansion of
+the hole is investigated. Then, the same result is derived using the techniques
+of Einstein's theory of general relativity. The field equations are solved for
+an infinite uniform universe and then for an infinite universe in which matter
+is uniformly distributed except for a spherical hole. Negative pressure caused
+by negative gravity is utilized. The physical significance of the cosmological
+constant is explained, and a new physical concept, that of the gravitational
+potential of a hole, is discussed. The relationship between the Newtonian
+potential for a hole and the Schwarzschild solution of the field equations is
+explored. Finally, the geodesic equations are considered. It is shown that
+photons and particles are deflected away from the hole. An application of this
+idea is pursued, in which a new cosmology based upon expanding holes in a
+uniform universe is developed. The microwave background radiation and Hubble's
+Law, among others, are explained. Finally, current astronomical data are used
+to compute a remarkably accurate value of Hubble's constant, as well as
+estimates of the average mass density of the universe and the cosmological
+constant.",9405075v1
+2002-11-21,SuSpect: a Fortran Code for the Supersymmetric and Higgs Particle Spectrum in the MSSM,"We present the Fortran code SuSpect version 2.3, which calculates the
+Supersymmetric and Higgs particle spectrum in the Minimal Supersymmetric
+Standard Model (MSSM). The calculation can be performed in constrained models
+with universal boundary conditions at high scales such as the gravity (mSUGRA),
+anomaly (AMSB) or gauge (GMSB) mediated breaking models, but also in the
+non-universal MSSM case with R-parity and CP conservation. Care has been taken
+to treat important features such as the renormalization group evolution of
+parameters between low and high energy scales, the consistent implementation of
+radiative electroweak symmetry breaking and the calculation of the physical
+masses of the Higgs bosons and supersymmetric particles taking into account the
+dominant radiative corrections. Some checks of important theoretical and
+experimental features, such as the absence of non desired minima, large
+fine-tuning in the electroweak symmetry breaking condition, as well as
+agreement with precision measurements can be performed. The program is user
+friendly, simple to use, self-contained and can easily be linked with other
+codes; it is rather fast and flexible, thus allowing scans of the parameter
+space with several possible options and choices for model assumptions and
+approximations.",0211331v2
+2004-11-04,Theoretical and Experimental Analysis of a Randomized Algorithm for Sparse Fourier Transform Analysis,"We analyze a sublinear RAlSFA (Randomized Algorithm for Sparse Fourier
+Analysis) that finds a near-optimal B-term Sparse Representation R for a given
+discrete signal S of length N, in time and space poly(B,log(N)), following the
+approach given in \cite{GGIMS}. Its time cost poly(log(N)) should be compared
+with the superlinear O(N log N) time requirement of the Fast Fourier Transform
+(FFT). A straightforward implementation of the RAlSFA, as presented in the
+theoretical paper \cite{GGIMS}, turns out to be very slow in practice. Our main
+result is a greatly improved and practical RAlSFA. We introduce several new
+ideas and techniques that speed up the algorithm. Both rigorous and heuristic
+arguments for parameter choices are presented. Our RAlSFA constructs, with
+probability at least 1-delta, a near-optimal B-term representation R in time
+poly(B)log(N)log(1/delta)/ epsilon^{2} log(M) such that
+||S-R||^{2}<=(1+epsilon)||S-R_{opt}||^{2}. Furthermore, this RAlSFA
+implementation already beats the FFTW for not unreasonably large N. We extend
+the algorithm to higher dimensional cases both theoretically and numerically.
+The crossover point lies at N=70000 in one dimension, and at N=900 for data on
+a N*N grid in two dimensions for small B signals where there is noise.",0411102v2
+2006-12-04,Krull dimension and deviation in certain parafree groups,"Hanna Neumann asked whether it was possible for two non-isomorphic residually
+nilpotent finitely generated (fg) groups, one of them free, to share the lower
+central sequence. Gilbert Baumslag answered the question in the affirmative and
+thus gave rise to parafree groups. A group G is termed parafree of rank n if it
+is residually nilpotent and shares the lower central sequence with a free group
+of rank n. The deviation of a finitely generated (fg) parafree group G is the
+difference between the minimum possible number of generators of G and the rank
+of G.
+  Let G be a fg group, then Hom(G,SL(2, C)) inherits the structure of an
+algebraic variety, denoted by R(G), and known as its ""representation variety"".
+If G is an n generated parafree group, then the deviation of G is 0 iff
+Dim(R(G))=3n. It is known that for n \ge 2 there exist infinitely many parafree
+groups of rank n and deviation 1 with non-isomorphic representation varieties
+of dimension 3n. In this paper it is shown that given integers n \ge 2, and k
+\ge 1, there exist infinitely many parafree groups of rank n and deviation k
+with non-isomorphic representation varieties of dimension different from 3n; in
+particular, it is shown that there exist infinitely many parafree groups G of
+rank n with Dim(R(G))> q, where q \ge 3n is an arbitrary integer.",0612102v2
+2004-07-27,Domain wall dynamics driven by adiabatic spin transfer torques,"In a first approximation, known as the adiabatic process, the direction of
+the spin polarization of currents is parallel to the local magnetization vector
+in a domain wall. Thus the spatial variation of the direction of the spin
+current inside the domain wall results in an adiabatical spin transfer torque
+on the magnetization. We show that domain wall motion driven by this spin
+torque has many unique features that do not exist in the conventional wall
+motion driven by a magnetic field. By analytically and numerically solving the
+Landau-Lifshitz-Gilbert equation along with the adiabatic spin torque in
+magnetic nanowires, we find the domain wall has its maximum velocity at the
+initial application of the current but the velocity decreases to zero as the
+domain wall begins to deform during its motion. We have computed domain wall
+displacement and domain wall deformation of nanowires, and concluded that the
+spin torque based on the adiabatic propagation of the spin current in the
+domain wall is unable to maintain wall movement. We also introduce a novel
+concept of domain wall inductance to characterize the capacity of the
+spin-torque induced magnetic energy stored in a domain wall. In the presence of
+domain wall pinning centers, we construct a phase diagram for the domain wall
+depinning by the combined action of the magnetic field and the spin current.",0407064v1
+1997-02-07,Two-pion correlations in Au+Au collisions at 10.8 GeV/c per nucleon,"Two-particle correlation functions for positive and negative pions have been
+measured in Au+Au collisions at 10.8~GeV/c per nucleon. The data were analyzed
+using one- and three-dimensional correlation functions. From the results of the
+three-dimensional fit the phase space density of pions was calculated. It is
+consistent with local thermal equilibrium.",9702008v1
+2007-01-30,Huddling behavior in emperor penguins : dynamics of huddling,"Although huddling was shown to be the key by which emperor penguins
+(Aptenodytes forsteri) save energy and sustain their breeding fast during the
+Antarctic winter, the intricacies of this social behavior have been poorly
+studied. We recorded abiotic variables with data loggers glued to the feathers
+of eight individually marked emperor penguins to investigate their
+thermoregulatory behavior and to estimate their ""huddling time budget""
+throughout the breeding season (pairing and incubation period). Contrary to the
+classic view, huddling episodes were discontinuous and of short and variable
+duration, lasting 1.6+/-1.7 (S.D.) h on average. Despite heterogeneous huddling
+groups, birds had equal access to the warmth of the huddles. Throughout the
+breeding season, males huddled for 38+/-18% (S.D.) of their time, which raised
+the ambient temperature that birds were exposed to above 0 degrees C (at
+average external temperatures of -17 degrees C). As a consequence of tight
+huddles, ambient temperatures were above 20 degrees C during 13+/-12% (S.D.) of
+their huddling time. Ambient temperatures increased up to 37.5 degrees C, close
+to birds' body temperature. This complex social behavior therefore enables all
+breeders to get a regular and equal access to an environment which allows them
+to save energy and successfully incubate their eggs during the Antarctic
+winter.",0701051v1
+2003-10-14,The Minimum Distance Problem for Two-Way Entanglement Purification,"Entanglement purification takes a number of noisy EPR pairs and processes
+them to produce a smaller number of more reliable pairs. If this is done with
+only a forward classical side channel, the procedure is equivalent to using a
+quantum error-correcting code (QECC). We instead investigate entanglement
+purification protocols with two-way classical side channels (2-EPPs) for finite
+block sizes. In particular, we consider the analog of the minimum distance
+problem for QECCs, and show that 2-EPPs can exceed the quantum Hamming bound
+and the quantum Singleton bound. We also show that 2-EPPs can achieve the rate
+k/n = 1 - (t/n) \log_2 3 - h(t/n) - O(1/n) (asymptotically reaching the quantum
+Hamming bound), where the EPP produces at least k good pairs out of n total
+pairs with up to t arbitrary errors, and h(x) = -x \log_2 x - (1-x) \log_2
+(1-x) is the usual binary entropy. In contrast, the best known lower bound on
+the rate of QECCs is the quantum Gilbert-Varshamov bound k/n \geq 1 - (2t/n)
+\log_2 3 - h(2t/n). Indeed, in some regimes, the known upper bound on the
+asymptotic rate of good QECCs is strictly below our lower bound on the
+achievable rate of 2-EPPs.",0310097v4
+2005-06-02,Enhanced algorithms for Local Search,"Let G=(V,E) be a finite graph, and f:V->N be any function. The Local Search
+problem consists in finding a local minimum of the function f on G, that is a
+vertex v such that f(v) is not larger than the value of f on the neighbors of v
+in G. In this note, we first prove a separation theorem slightly stronger than
+the one of Gilbert, Hutchinson and Tarjan for graphs of constant genus. This
+result allows us to enhance a previously known deterministic algorithm for
+Local Search with query complexity O(\log n)\cdot d+O(\sqrt{g})\cdot\sqrt{n},
+so that we obtain a deterministic query complexity of
+d+O(\sqrt{g})\cdot\sqrt{n}, where n is the size of G, d is its maximum degree,
+and $g$ is its genus. We also give a quantum version of our algorithm, whose
+query complexity is of O(\sqrt{d})+O(\sqrt[4]{g})\cdot\sqrt[4]{n}\log\log n.
+Our deterministic and quantum algorithms have query complexities respectively
+smaller than the generic algorithms of Aldous and of Aaronson for large classes
+of graphs, including graphs of bounded genus and planar graphs. Independently
+from this work, Zhang has recently given a quantum algorithm which finds a
+local minimum on the planar grid over \{1,...,\sqrt{n}\}^2 using
+O(\sqrt[4]{n}(\log\log n)^2) queries. Our quantum algorithm can be viewed as a
+strongly generalized, and slightly enhanced version of this algorithm.",0506019v1
+2007-09-27,Predictions of the causal entropic principle for environmental conditions of the universe,"The causal entropic principle has been proposed as a superior alternative to
+the anthropic principle for understanding the magnitude of the cosmological
+constant. In this approach, the probability to create observers is assumed to
+be proportional to the entropy production \Delta S in a maximal causally
+connected region -- the causal diamond. We improve on the original treatment by
+better quantifying the entropy production due to stars, using an analytic model
+for the star formation history which accurately accounts for changes in
+cosmological parameters. We calculate the dependence of \Delta S on the density
+contrast Q=\delta\rho/\rho, and find that our universe is much closer to the
+most probable value of Q than in the usual anthropic approach and that
+probabilities are relatively weakly dependent on this amplitude. In addition,
+we make first estimates of the dependence of \Delta S on the baryon fraction
+and overall matter abundance. Finally, we also explore the possibility that
+decays of dark matter, suggested by various observed gamma ray excesses, might
+produce a comparable amount of entropy to stars.",0709.4443v2
+2007-10-24,"The Impact of Halo Properties, Energy Feedback and Projection Effects on the Mass-SZ Flux Relation","We present a detailed analysis of the intrinsic scatter in the integrated SZ
+effect - cluster mass (Y-M) relation, using semi-analytic and simulated cluster
+samples. Specifically, we investigate the impact on the Y-M relation of energy
+feedback, variations in the host halo concentration and substructure
+populations, and projection effects due to unresolved clusters along the line
+of sight (the SZ background). Furthermore, we investigate at what radius (or
+overdensity) one should measure the integrated SZE and define cluster mass so
+as to achieve the tightest possible scaling. We find that the measure of Y with
+the least scatter is always obtained within a smaller radius than that at which
+the mass is defined; e.g. for M_{200} (M_{500}) the scatter is least for
+Y_{500} (Y_{1100}). The inclusion of energy feedback in the gas model
+significantly increases the intrinsic scatter in the Y-M relation due to larger
+variations in the gas mass fraction compared to models without feedback. We
+also find that variations in halo concentration for clusters of a given mass
+may partly explain why the integrated SZE provides a better mass proxy than the
+central decrement. Substructure is found to account for approximately 20% of
+the observed scatter in the Y-M relation. Above M_{200} = 2x10^{14} h^{-1}
+msun, the SZ background does not significantly effect cluster mass
+measurements; below this mass, variations in the background signal reduce the
+optimal angular radius within which one should measure Y to achieve the
+tightest scaling with M_{200}.",0710.4555v1
+2007-10-31,Spin-Torque Driven Magnetization Dynamics: Micromagnetic Modelling,"In this paper we present an overview of recent progress made in the
+understanding of the spin-torque induced magnetization dynamics in nanodevices
+using mesoscopic micromagnetic simulations. We first specify how a spin-torque
+term may be added to the usual Landau-Lifshitz-Gilbert equation of
+magnetization motion and detail its physical meaning. After a brief description
+of spin-torque driven dynamics in the macrospin approximation, we discuss the
+validity of this approximation for various experimentally relevant geometries.
+Next, we perform a detailed comparison between accurate experimental data
+obtained from nanopillar devices and corresponding numerical modelling. We show
+that, on the one hand, many qualitatively important features of the observed
+magnetization dynamics (e.g., non-linear frequency shift and frequency jumps
+with increasing current) can be satisfactory explained by sophisticated
+micromagnetic models, but on the other hand, understanding of these experiments
+is still far from being complete. We proceed with the numerical analysis of
+point-contact experiments, where an even more complicated magnetization
+dynamics is observed. Simulations reveal that such a rich behaviour is due to
+the formation of several strongly non-linear oscillation modes. In the last
+part of the paper we emphasize the importance of sample characterization and
+conclude with some important remarks concerning the relation between
+micromagnetic modelling and real experiments.",0710.5924v1
+2007-11-19,The Kohn-Sham system in one-matrix functional theory,"A system of electrons in a local or nonlocal external potential can be
+studied with 1-matrix functional theory (1MFT), which is similar to density
+functional theory (DFT) but takes the one-particle reduced density matrix
+(1-matrix) instead of the density as its basic variable. Within 1MFT, Gilbert
+derived [PRB 12, 2111 (1975)] effective single-particle equations analogous to
+the Kohn-Sham (KS) equations in DFT. The self-consistent solution of these
+1MFT-KS equations reproduces not only the density of the original electron
+system but also its 1-matrix. While in DFT it is usually possible to reproduce
+the density using KS orbitals with integer (0 or 1) occupancy, in 1MFT
+reproducing the 1-matrix requires in general fractional occupancies. The
+variational principle implies that the KS eigenvalues of all fractionally
+occupied orbitals must collapse at self-consistency to a single level, equal to
+the chemical potential. We show that as a consequence of the degeneracy the
+iteration of the KS equations is intrinsically divergent. Fortunately, the
+level shifting method, commonly introduced in Hartree-Fock calculations, is
+always able to force convergence. We introduce an alternative derivation of the
+1MFT-KS equations that allows control of the eigenvalue collapse by
+constraining the occupancies. As an explicit example, we apply the 1MFT-KS
+scheme to calculate the ground state 1-matrix of an exactly solvable two-site
+Hubbard model.",0711.2996v1
+2007-12-01,"On Myopic Sensing for Multi-Channel Opportunistic Access: Structure, Optimality, and Performance","We consider a multi-channel opportunistic communication system where the
+states of these channels evolve as independent and statistically identical
+Markov chains (the Gilbert-Elliot channel model). A user chooses one channel to
+sense and access in each slot and collects a reward determined by the state of
+the chosen channel. The problem is to design a sensing policy for channel
+selection to maximize the average reward, which can be formulated as a
+multi-arm restless bandit process. In this paper, we study the structure,
+optimality, and performance of the myopic sensing policy. We show that the
+myopic sensing policy has a simple robust structure that reduces channel
+selection to a round-robin procedure and obviates the need for knowing the
+channel transition probabilities. The optimality of this simple policy is
+established for the two-channel case and conjectured for the general case based
+on numerical results. The performance of the myopic sensing policy is analyzed,
+which, based on the optimality of myopic sensing, characterizes the maximum
+throughput of a multi-channel opportunistic communication system and its
+scaling behavior with respect to the number of channels. These results apply to
+cognitive radio networks, opportunistic transmission in fading environments,
+and resource-constrained jamming and anti-jamming.",0712.0035v3
+2007-12-12,Two-connected graphs with prescribed three-connected components,"We adapt the classical 3-decomposition of any 2-connected graph to the case
+of simple graphs (no loops or multiple edges). By analogy with the
+block-cutpoint tree of a connected graph, we deduce from this decomposition a
+bicolored tree tc(g) associated with any 2-connected graph g, whose white
+vertices are the 3-components of g (3-connected components or polygons) and
+whose black vertices are bonds linking together these 3-components, arising
+from separating pairs of vertices of g. Two fundamental relationships on graphs
+and networks follow from this construction. The first one is a dissymmetry
+theorem which leads to the expression of the class B=B(F) of 2-connected
+graphs, all of whose 3-connected components belong to a given class F of
+3-connected graphs, in terms of various rootings of B. The second one is a
+functional equation which characterizes the corresponding class R=R(F) of
+two-pole networks all of whose 3-connected components are in F. All the
+rootings of B are then expressed in terms of F and R. There follow
+corresponding identities for all the associated series, in particular the edge
+index series. Numerous enumerative consequences are discussed.",0712.1869v2
+2008-03-13,Optimal spatial transportation networks where link-costs are sublinear in link-capacity,"Consider designing a transportation network on $n$ vertices in the plane,
+with traffic demand uniform over all source-destination pairs. Suppose the cost
+of a link of length $\ell$ and capacity $c$ scales as $\ell c^\beta$ for fixed
+$0<\beta<1$. Under appropriate standardization, the cost of the minimum cost
+Gilbert network grows essentially as $n^{\alpha(\beta)}$, where $\alpha(\beta)
+= 1 - \frac{\beta}{2}$ on $0 < \beta \leq {1/2}$ and $\alpha(\beta) = {1/2} +
+\frac{\beta}{2}$ on ${1/2} \leq \beta < 1$. This quantity is an upper bound in
+the worst case (of vertex positions), and a lower bound under mild regularity
+assumptions. Essentially the same bounds hold if we constrain the network to be
+efficient in the sense that average route-length is only $1 + o(1)$ times
+average straight line length. The transition at $\beta = {1/2}$ corresponds to
+the dominant cost contribution changing from short links to long links. The
+upper bounds arise in the following type of hierarchical networks, which are
+therefore optimal in an order of magnitude sense. On the large scale, use a
+sparse Poisson line process to provide long-range links. On the medium scale,
+use hierachical routing on the square lattice. On the small scale, link
+vertices directly to medium-grid points. We discuss one of many possible
+variant models, in which links also have a designed maximum speed $s$ and the
+cost becomes $\ell c^\beta s^\gamma$.",0803.2037v1
+2008-03-24,Was the Andromeda Stream Produced by a Disk Galaxy?,"The halo region of M31 exhibits a startling level of stellar inhomogeneities,
+the most prominent of which is the ""giant southern stream"". Our previous
+analysis indicates that this stream, as well as several other observed
+features, are products of the tidal disruption of a single satellite galaxy
+with stellar mass ~10^9 solar masses less than 1 Gyr ago. Here we show that the
+specific observed morphology of the stream and halo debris favors a cold,
+rotating, disk-like progenitor over a dynamically hot, non-rotating one. These
+observed characteristics include the asymmetric distribution of stars along the
+stream cross-section and its metal-rich core/metal-poor sheath structure. We
+find that a disk-like progenitor can also give rise to arc-like features on the
+minor axis at certain orbital phases that resemble the recently discovered
+minor-axis ""streams"", even reproducing the lower observed metallicity of these
+streams. Though interpreted by the discoverers as new, independent tidal
+streams, our analysis suggests that these minor-axis streams may alternatively
+arise from the progenitor of the giant southern stream. Overall, our study
+points the way to a more complete reconstruction of the stream progenitor and
+its merger with M31, based on the emerging picture that most of the major
+inhomogeneities observed in the M31 halo share a common origin with the giant
+stream.",0803.3476v2
+2008-04-23,Geometric dynamics of Vlasov kinetic theory and its moments,"The Vlasov equation of kinetic theory is introduced and the Hamiltonian
+structure of its moments is presented. Then we focus on the geodesic evolution
+of the Vlasov moments. As a first step, these moment equations generalize the
+Camassa-Holm equation to its multi-component version. Subsequently, adding
+electrostatic forces to the geodesic moment equations relates them to the
+Benney equations and to the equations for beam dynamics in particle
+accelerators. Next, we develop a kinetic theory for self assembly in
+nano-particles. Darcy's law is introduced as a general principle for
+aggregation dynamics in friction dominated systems (at different scales). Then,
+a kinetic equation is introduced for the dissipative motion of isotropic
+nano-particles. The zeroth-moment dynamics of this equation recovers the
+classical Darcy's law at the macroscopic level. A kinetic-theory description
+for oriented nano-particles is also presented. At the macroscopic level, the
+zeroth moments of this kinetic equation recover the magnetization dynamics of
+the Landau-Lifshitz-Gilbert equation. The moment equations exhibit the
+spontaneous emergence of singular solutions (clumpons) that finally merge in
+one singularity. This behaviour represents aggregation and alignment of
+oriented nano-particles. Finally, the Smoluchowski description is derived from
+the dissipative Vlasov equation for anisotropic interactions. Various levels of
+approximate Smoluchowski descriptions are proposed as special cases of the
+general treatment. As a result, the macroscopic momentum emerges as an
+additional dynamical variable that in general cannot be neglected.",0804.3676v1
+2008-05-05,On Expanded Cyclic Codes,"The paper has a threefold purpose. The first purpose is to present an
+explicit description of expanded cyclic codes defined in $\GF(q^m)$. The
+proposed explicit construction of expanded generator matrix and expanded parity
+check matrix maintains the symbol-wise algebraic structure and thus keeps many
+important original characteristics. The second purpose of this paper is to
+identify a class of constant-weight cyclic codes. Specifically, we show that a
+well-known class of $q$-ary BCH codes excluding the all-zero codeword are
+constant-weight cyclic codes. Moreover, we show this class of codes achieve the
+Plotkin bound. The last purpose of the paper is to characterize expanded cyclic
+codes utilizing the proposed expanded generator matrix and parity check matrix.
+We characterize the properties of component codewords of a codeword and
+particularly identify the precise conditions under which a codeword can be
+represented by a subbasis. Our developments reveal an alternative while more
+general view on the subspace subcodes of Reed-Solomon codes. With the new
+insights, we present an improved lower bound on the minimum distance of an
+expanded cyclic code by exploiting the generalized concatenated structure. We
+also show that the fixed-rate binary expanded Reed-Solomon codes are
+asymptotically ""bad"", in the sense that the ratio of minimum distance over code
+length diminishes with code length going to infinity. It overturns the
+prevalent conjecture that they are ""good"" codes and deviates from the ensemble
+of generalized Reed-Solomon codes which asymptotically achieves the
+Gilbert-Varshamov bound.",0805.0615v2
+2008-05-14,Path Diversity over Packet Switched Networks: Performance Analysis and Rate Allocation,"Path diversity works by setting up multiple parallel connections between the
+end points using the topological path redundancy of the network. In this paper,
+\textit{Forward Error Correction} (FEC) is applied across multiple independent
+paths to enhance the end-to-end reliability. Network paths are modeled as
+erasure Gilbert-Elliot channels. It is known that over any erasure channel,
+\textit{Maximum Distance Separable} (MDS) codes achieve the minimum probability
+of irrecoverable loss among all block codes of the same size. Based on the
+adopted model for the error behavior, we prove that the probability of
+irrecoverable loss for MDS codes decays exponentially for an asymptotically
+large number of paths. Then, optimal rate allocation problem is solved for the
+asymptotic case where the number of paths is large. Moreover, it is shown that
+in such asymptotically optimal rate allocation, each path is assigned a
+positive rate \textit{iff} its quality is above a certain threshold. The
+quality of a path is defined as the percentage of the time it spends in the bad
+state. Finally, using dynamic programming, a heuristic suboptimal algorithm
+with polynomial runtime is proposed for rate allocation over a finite number of
+paths. This algorithm converges to the asymptotically optimal rate allocation
+when the number of paths is large. The simulation results show that the
+proposed algorithm approximates the optimal rate allocation (found by
+exhaustive search) very closely for practical number of paths, and provides
+significant performance improvement compared to the alternative schemes of rate
+allocation.",0805.2185v1
+2008-06-25,HAT-P-9b: A Low Density Planet Transiting a Moderately Faint F star,"We report the discovery of a planet transiting a moderately faint (V=12.3
+mag) late F star, with an orbital period of 3.92289 +/- 0.00004 days. From the
+transit light curve and radial velocity measurements we determine that the
+radius of the planet is R_p = 1.40 +/- 0.06 R_Jup and that the mass is M_p =
+0.78 +/- 0.09 M_Jup. The density of the new planet, rho = 0.35 +/- 0.06 g
+cm^{-3}, fits to the low-density tail of the currently known transiting
+planets. We find that the center of transit is at T_c = 2454417.9077 +/- 0.0003
+(HJD), and the total transit duration is 0.143 +/- 0.004 days. The host star
+has M_s = 1.28 +/- 0.13 M_Sun and R_s = 1.32 +/- 0.07 R_Sun.",0806.4008v2
+2008-07-07,Micropropagation of three genotypes of Indian mustard [{Brassica juncea} (L.) Czern.] using seedling-derived transverse thin cell layer (tTCL) explants,"Micropropagation of three genotypes of Indian mustard [\textit{Brassica
+juncea} (L.) Czern.] using 7-days old seedling-derived transverse thin cell
+layer (tTCL) explants was accomplished.
+  The genotype, explant source and addition of silver nitrate to the medium
+significantly influenced shoot bud induction. MS medium with 26.6 $\mu$M of
+6-Benzylaminopurin (BAP) and 3.22 $\mu$M of 1-naphtaleneacetic acid (NAA) was
+identical (in the case of cotyledon tTCLs whatever the organ) and superior for
+the induction of buds (in the cases of petiole tTCL explants of genotypes 1 and
+2 and hypocotyl tTCL explants of genotypes 1 and 3) than 53.3 $\mu$M of BAP and
+3.22 $\mu$M of NAA. However, 53.3 $\mu$M of BAP was superior for the induction
+of buds than 26.6 $\mu$M in the presence of the same concentration of NAA for
+petiole tTCL explants of genotype 3 and hypocotyl tTCL explants of genotype 2.
+  The addition of silver nitrate significantly enhanced the rate of shoot
+induction in all genotypes. Cotyledon-derived tTCL explants exhibited the
+highest shoot bud induction potential and was followed by petiole- and
+hypocotyl-derived ones. Addition of 10 $\mu$M of silver nitrate to BAP and NAA
+supplemented medium induced higher frequency shoot bud induction (up to 100 %)
+with the highest means of 4.45 shoots per cotyledon-derived tTCL explants
+obtained with the genotype 2. Shoot regenerated were rooted on MS basal medium
+without PGRs which induced 99 % of roots per shoot. The plantlets established
+in greenhouse conditions with 99 % survival, flowered normally and set seeds.",0807.1061v1
+2008-07-18,"On Probability Distributions for Trees: Representations, Inference and Learning","We study probability distributions over free algebras of trees. Probability
+distributions can be seen as particular (formal power) tree series [Berstel et
+al 82, Esik et al 03], i.e. mappings from trees to a semiring K . A widely
+studied class of tree series is the class of rational (or recognizable) tree
+series which can be defined either in an algebraic way or by means of
+multiplicity tree automata. We argue that the algebraic representation is very
+convenient to model probability distributions over a free algebra of trees.
+First, as in the string case, the algebraic representation allows to design
+learning algorithms for the whole class of probability distributions defined by
+rational tree series. Note that learning algorithms for rational tree series
+correspond to learning algorithms for weighted tree automata where both the
+structure and the weights are learned. Second, the algebraic representation can
+be easily extended to deal with unranked trees (like XML trees where a symbol
+may have an unbounded number of children). Both properties are particularly
+relevant for applications: nondeterministic automata are required for the
+inference problem to be relevant (recall that Hidden Markov Models are
+equivalent to nondeterministic string automata); nowadays applications for Web
+Information Extraction, Web Services and document processing consider unranked
+trees.",0807.2983v1
+2008-11-02,Stretch-Twist torus dynamo in compact Riemannian manifolds,"Earlier Arnold, Zeldovich, Ruzmaikin and Sokoloff [\textbf{JETP (1982)}] have
+computed the eigenvalue of a uniform stretching torus transformation which
+result on the first Riemann metric solution of the dynamo action problem.
+Recently some other attempts to obtain Riemann metrics representing dynamo
+action through conformal maps have been undertaken [{\textbf{Phys. Plasmas 14
+(2007)}]. Earlier, Gilbert [\textbf{Proc. Roy. Soc. London A(2003)}] has
+investigated a more realistic dynamo map solution than the one presented by
+Arnold et al by producing a shearing of the Arnold's cat map, by eigenvalue
+problem of a dynamo operator. In this paper, the eigenvalue of the Riemann
+twisted torus dynamo flow metric is obtained as the ratio between the poloidal
+and toroidal components of the flow. This result is obtained from the Euler
+equation. In the twisted torus, the eigenvalue of the Riemann metric is
+${m}_{\pm}=\frac{1\pm{\sqrt{5}}}{2}$, which is quite close to the value
+obtained by Arnold. In the case the viscosity Reynolds number $Re\to{\infty}$,
+the torus flow is unstable as one approaches the torus axis. In Arnold's dynamo
+metric the eigenvalues are ${\chi}_{\pm}=\frac{3\pm{\sqrt{5}}}{2}$ which are
+very close to the above value. Eigenvalues determine the growth rates of the
+velocity ratio between poloidal and toroidal components of the flow. The curved
+flow in torus follow previous work by Chen et al [\textbf{Phys Fluids (2006)}].
+The ${\alpha}$-effect dynamo is shown to be a second-order effect in the torus
+curvature and velocity flow. Loop dynamo flows and maps are also discussed.",0811.0142v1
+2008-11-21,Geodesic dynamo chaotic flows and non-Anosov maps in twisted magnetic flux tubes,"Recently Tang and Boozer [{\textbf{Phys. Plasmas (2000)}}], have investigated
+the anisotropies in magnetic field dynamo evolution, from local Lyapunov
+exponents, giving rise to a metric tensor, in the Alfven twist in magnetic flux
+tubes (MFTs). Thiffeault and Boozer [\textbf{Chaos}(2001)] have investigated
+the how the vanishing of Riemann curvature constrained the Lyapunov exponential
+stretching of chaotic flows. In this paper, Tang-Boozer-Thiffeault differential
+geometric framework is used to investigate effects of twisted magnetic flux
+tube filled with helical chaotic flows on the Riemann curvature tensor. When
+Frenet torsion is positive, the Riemann curvature is unstable, while the
+negative torsion induces an stability when time $t\to{\infty}$. This enhances
+the dynamo action inside the MFTs. The Riemann metric, depends on the radial
+random flows along the poloidal and toroidal directions. The Anosov flows has
+been applied by Arnold, Zeldovich, Ruzmaikin and Sokoloff [\textbf{JETP
+(1982)}] to build a uniformly stretched dynamo flow solution, based on Arnold's
+Cat Map. It is easy to show that when the random radial flow vanishes, the
+magnetic field vanishes, since the exponential Lyapunov stretches vanishes.
+This is an example of the application of the Vishik's anti-fast dynamo theorem
+in the magnetic flux tubes. Geodesic flows of both Arnold and twisted MFT
+dynamos are investigated. It is shown that a constant random radial flow can be
+obtained from the geodesic equation. Throughout the paper one assumes, the
+reasonable plasma astrophysical hypothesis of the weak torsion. Pseudo-Anosov
+dynamo flows and maps have also been addressed by Gilbert [\textbf{Proc Roy Soc
+A London (1993)}",0811.3630v1
+2008-12-03,Gravitino Dark Matter and the Cosmic Lithium Abundances,"Supersymmetric extensions of the standard model of particle physics assuming
+the gravitino to be the lightest supersymmetric particle (LSP), and with the
+next-to-LSP decaying to the gravitino during Big Bang nucleosynthesis, are
+analyzed. Particular emphasis is laid on their potential to solve the ""Li7
+problem"", an apparent factor 2-4 overproduction of Li7 in standard Big Bang
+nucleosynthesis (BBN), their production of cosmologically important amounts of
+Li6, as well as the resulting gravitino dark matter densities in these models.
+The study includes several improvements compared to prior studies. Heavy
+gravitinos in the constrained minimal supersymmetric standard model (CMMSM) are
+reanalyzed, whereas light gravitinos in gauge-mediated supersymmetry breaking
+scenarios (GMSB) are studied for the first time. It is confirmed that decays of
+NLSP staus to heavy gravitinos, while producing all the dark matter, may at the
+same time resolve the Li7 problem. For NLSP decay times ~ 1000 sec, such
+scenarios also lead to cosmologically important Li6 (and possibly Be9)
+abundances. However, as such scenarios require heavy > 1 TeV staus they are
+likely not testable at the LHC. It is found that decays of NLSP staus to light
+gravitinos may lead to significant Li6 (and Be9) abundances, whereas NLSP
+neutralinos decaying into light gravitinos may solve the Li7 problem. Though
+both scenarios are testable at the LHC they may not lead to the production of
+the bulk of the dark matter. A section of the paper outlines particle
+properties required to significantly reduce the Li7 abundance, and/or enhance
+the Li6 (and possibly Be9) abundances, by the decay of an arbitrary relic
+particle.",0812.0788v2
+2009-01-26,A Bayesian framework for estimating vaccine efficacy per infectious contact,"In vaccine studies for infectious diseases such as human immunodeficiency
+virus (HIV), the frequency and type of contacts between study participants and
+infectious sources are among the most informative risk factors, but are often
+not adequately adjusted for in standard analyses. Such adjustment can improve
+the assessment of vaccine efficacy as well as the assessment of risk factors.
+It can be attained by modeling transmission per contact with infectious
+sources. However, information about contacts that rely on self-reporting by
+study participants are subject to nontrivial measurement error in many studies.
+We develop a Bayesian hierarchical model fitted using Markov chain Monte Carlo
+(MCMC) sampling to estimate the vaccine efficacy controlled for exposure to
+infection, while adjusting for measurement error in contact-related factors.
+Our method is used to re-analyze two recent HIV vaccine studies, and the
+results are compared with the published primary analyses that used standard
+methods. The proposed method could also be used for other vaccines where
+contact information is collected, such as human papilloma virus vaccines.",0901.4025v1
+2009-01-28,Theoretical characterization of a model of aragonite crystal orientation in red abalone nacre,"Nacre, commonly known as mother-of-pearl, is a remarkable biomineral that in
+red abalone consists of layers of 400-nm thick aragonite crystalline tablets
+confined by organic matrix sheets, with the $(001)$ crystal axes of the
+aragonite tablets oriented to within $\pm$ 12 degrees from the normal to the
+layer planes. Recent experiments demonstrate that this orientational order
+develops over a distance of tens of layers from the prismatic boundary at which
+nacre formation begins.
+  Our previous simulations of a model in which the order develops because of
+differential tablet growth rates (oriented tablets growing faster than
+misoriented ones) yield patterns of tablets that agree qualitatively and
+quantitatively with the experimental measurements. This paper presents an
+analytical treatment of this model, focusing on how the dynamical development
+and eventual degree of order depend on model parameters. Dynamical equations
+for the probability distributions governing tablet orientations are introduced
+whose form can be determined from symmetry considerations and for which
+substantial analytic progress can be made. Numerical simulations are performed
+to relate the parameters used in the analytic theory to those in the
+microscopic growth model. The analytic theory demonstrates that the dynamical
+mechanism is able to achieve a much higher degree of order than naive estimates
+would indicate.",0901.4482v1
+2009-02-07,Partially-erupting prominences: a comparison between observations and model-predicted observables,"AIM: To investigate several partially-erupting prominences to study their
+relationship with other CME-associated phenomena and to compare these
+observations with observables predicted by a model of partially-expelled flux
+ropes (Gibson & Fan, 2006a, b).
+  METHODS: We have studied 6 selected events with partially-erupting
+prominences using multi wavelength observations recorded by the
+Extreme-ultraviolet Imaging Telescope (EIT), Transition Region and Coronal
+Explorer (TRACE), Mauna Loa Solar Observatory (MLSO), Big Bear Solar
+Observatory (BBSO) and soft X-ray telescope (SXT). The observational features
+associated with partially-erupting prominences were then compared with the
+predicted observables from the model.
+  RESULTS: The partially-expelled-flux-rope (PEFR) model of Gibson & Fan
+(2006a, b) can explain the partial eruption of these prominences, and in
+addition predicts a variety of other CME-related observables that provide
+evidence for internal reconnection during eruption. We find that all of the
+partially-erupting prominences studied in this paper exhibit indirect evidence
+for internal reconnection. Moreover, all cases showed evidence of at least one
+observable unique to the PEFR model, e.g., dimmings external to the source
+region, and/or a soft X-ray cusp overlying a reformed sigmoid.
+  CONCLUSIONS: The PEFR model provides a plausible mechanism to explain the
+observed evolution of partially-erupting-prominence-associated CMEs in our
+study.",0902.1228v1
+2009-03-03,Proportional hazards models with continuous marks,"For time-to-event data with finitely many competing risks, the proportional
+hazards model has been a popular tool for relating the cause-specific outcomes
+to covariates [Prentice et al. Biometrics 34 (1978) 541--554]. This article
+studies an extension of this approach to allow a continuum of competing risks,
+in which the cause of failure is replaced by a continuous mark only observed at
+the failure time. We develop inference for the proportional hazards model in
+which the regression parameters depend nonparametrically on the mark and the
+baseline hazard depends nonparametrically on both time and mark. This work is
+motivated by the need to assess HIV vaccine efficacy, while taking into account
+the genetic divergence of infecting HIV viruses in trial participants from the
+HIV strain that is contained in the vaccine, and adjusting for covariate
+effects. Mark-specific vaccine efficacy is expressed in terms of one of the
+regression functions in the mark-specific proportional hazards model. The new
+approach is evaluated in simulations and applied to the first HIV vaccine
+efficacy trial.",0903.0487v1
+2009-03-06,Five More Massive Binaries in the Cygnus OB2 Association,"We present the orbital solutions for four OB spectroscopic binaries, MT145,
+GSC 03161-00815, 2MASS J20294666+4105083, and Schulte 73, and the partial
+orbital solution to the B spectroscopic binary, MT372, as part of an ongoing
+study to determine the distribution of orbital parameters for massive binaries
+in the Cygnus OB2 Association. MT145 is a new, single-lined, moderately
+eccentric (e=0.291+/-0.009) spectroscopic binary with period of 25.140+/-0.008
+days. GSC 03161-00815 is a slightly eccentric (e=0.10+/-0.01), eclipsing,
+interacting and double-lined spectroscopic binary with a period of
+4.674+/-0.004 days. 2MASS J20294666+4105083 is a moderately eccentric
+(e=0.273+/-0.002) double-lined spectroscopic binary with a period of
+2.884+/-0.001 days. Schulte 73 is a slightly eccentric (e=0.169+/-0.009),
+double-lined spectroscopic binary with a period of 17.28+/-0.03 days and the
+first ""twin"" in our survey with a mass ratio of q=0.99+/-0.02. MT372 is a
+single-lined, eclipsing system with a period of 2.228 days and low eccentricity
+(e~0). Of the now 18 known OB binaries in Cyg OB2, 14 have periods and mass
+ratios. Emerging evidence also shows that the distribution of log(P) is flat
+and consistent with Oepik's Law.",0903.1265v1
+2009-03-16,The Transit Light Curve Project. XII. Six Transits of the Exoplanet XO-2b,"We present photometry of six transits of the exoplanet XO-2b. By combining
+the light-curve analysis with theoretical isochrones to determine the stellar
+properties, we find the planetary radius to be 0.996 +0.031/-0.018 rjup and the
+planetary mass to be 0.565 +/- 0.054 mjup. These results are consistent with
+those reported previously, and are also consistent with theoretical models for
+gas giant planets. The mid-transit times are accurate to within 1 min and are
+consistent with a constant period. However, the period we derive differs by 2.5
+sigma from the previously published period. More data are needed to tell
+whether the period is actually variable (as it would be in the presence of an
+additional body) or if the timing errors have been underestimated.",0903.2687v1
+2009-03-19,Approximation of Bounds on Mixed Level Orthogonal Arrays,"Mixed level orthogonal arrays are basic structures in experimental design. We
+develop three algorithms that compute Rao and Gilbert-Varshamov type bounds for
+mixed level orthogonal arrays. The computational complexity of the terms
+involved in these bounds can grow fast as the parameters of the arrays increase
+and this justifies the construction of these algorithms. The first is a
+recursive algorithm that computes the bounds exactly, the second is based on an
+asymptotic analysis and the third is a simulation algorithm. They are all based
+on the representation of the combinatorial expressions that appear in the
+bounds as expectations involving a symmetric random walk. The Markov property
+of the underlying random walk gives the recursive formula to compute the
+expectations. A large deviation (LD) analysis of the expectations provide the
+asymptotic algorithm. The asymptotically optimal importance sampling (IS) of
+the same expectation provides the simulation algorithm. Both the LD analysis
+and the construction of the IS algorithm uses a representation of these
+problems as a sequence of stochastic optimal control problems converging to a
+limit calculus of variations problem. The construction of the IS algorithm uses
+a recently discovered method of using subsolutions to the Hamilton Jacobi
+Bellman equation associated with the limit problem.",0903.3438v2
+2009-10-10,Multi-channel Opportunistic Access: A Case of Restless Bandits with Multiple Plays,"This paper considers the following stochastic control problem that arises in
+opportunistic spectrum access: a system consists of n channels (Gilbert-Elliot
+channels)where the state (good or bad) of each channel evolves as independent
+and identically distributed Markov processes. A user can select exactly k
+channels to sense and access (based on the sensing result) in each time slot. A
+reward is obtained whenever the user senses and accesses a good channel. The
+objective is to design a channel selection policy that maximizes the expected
+discounted total reward accrued over a finite or infinite horizon. In our
+previous work we established the optimality of a greedy policy for the special
+case of k = 1 (i.e., single channel access) under the condition that the
+channel state transitions are positively correlated over time. In this paper we
+show under the same condition the greedy policy is optimal for the general case
+of k >= 1; the methodology introduced here is thus more general. This problem
+may be viewed as a special case of the restless bandit problem, with multiple
+plays. We discuss connections between the current problem and existing
+literature on this class of problems.",0910.1954v1
+2010-03-12,Anosov branches of dynamo spectra in one dimensional plasmas,"Recently Guenther et al the globally diagonalized ${\alpha}^{2}$ dynamo
+operator spectrum [J Phys A 2007) in mean field media, and its Krein space
+related perturbation theory [J Phys A 2006). Earlier, an example of fast
+dynamos in stretch shear and fold Anosov maps have been given by Gilbert [PRSA
+[1993)). In this paper, analytical solutions representing general turbulent
+dynamo filaments are obtained in resistive plasmas. When turbulent diffusivity
+is present and kinetic helicity vanishes, a fast dynamo mode is obtained, and
+the Anosov eigenvalue obtained. The magnetic field lays down on a Frenet 2
+plane along the filaments embedded in a 3D flow. Curvature effects on fast
+dynamo are also investigate. In case of weak curvature filaments the one
+dimensional manifolds in plasmas present a fast dynamo action. A parallel
+result has been obtained by Chicone et al [Comm Math Phys), in the case fast
+dynamo spectrum in two dimensional compact Riemannian manifolds of negative
+constant curvature, called Anosov spaces. While problems of embedding may
+appear in their case here no embedding problems appear since the one
+dimensional curved plasmas are embedded in three dimensional Euclidean spaces.
+In the examples considered here, equipartion between normal and binormal
+components of the magnetic field components is considered. In the opposite
+case, non Anosov oscillatory, purely imaginary, branches of the spectrum are
+found in dynamo manifold. Negative constant curvature non-compact
+$\textbf{H}^{2}$ manifold, has also been used in one-component electron 2D
+plasma by Fantoni and Tellez (Stat. Phys, (2008))",1003.2482v1
+2010-04-05,"A Prograde, Low-Inclination Orbit for the Very Hot Jupiter WASP-3b","We present new spectroscopic and photometric observations of the transiting
+exoplanetary system WASP-3. Spectra obtained during two separate transits
+exhibit the Rossiter-McLaughlin (RM) effect and allow us to estimate the
+sky-projected angle between the planetary orbital axis and the stellar rotation
+axis, lambda = 3.3^{+2.5}_{-4.4} degrees. This alignment between the axes
+suggests that WASP-3b has a low orbital inclination relative to the equatorial
+plane of its parent star. During our first night of spectroscopic measurements,
+we observed an unexpected redshift briefly exceeding the expected sum of the
+orbital and RM velocities by 140 m/s. This anomaly could represent the
+occultation of material erupting from the stellar photosphere, although it is
+more likely to be an artifact caused by moonlight scattered into the
+spectrograph.",1004.0692v2
+2010-06-09,"NLTT 41135: a field M-dwarf + brown dwarf eclipsing binary in a triple system, discovered by the MEarth observatory","We report the discovery of an eclipsing companion to NLTT 41135, a nearby M5
+dwarf that was already known to have a wider, slightly more massive common
+proper motion companion, NLTT 41136, at 2.4 arcsec separation. Analysis of
+combined-light and radial velocity curves of the system indicates that NLTT
+41135B is a 31-34 +/- 3 MJup brown dwarf (where the range depends on the
+unknown metallicity of the host star) on a circular orbit. The visual M-dwarf
+pair appears to be physically bound, so the system forms a hierarchical triple,
+with masses approximately in the ratio 8:6:1. The eclipses are grazing,
+preventing an unambiguous measurement of the secondary radius, but follow-up
+observations of the secondary eclipse (e.g. with the James Webb Space
+Telescope) could permit measurements of the surface brightness ratio between
+the two objects, and thus place constraints on models of brown dwarfs.",1006.1793v1
+2010-09-28,Connectivity in Sub-Poisson Networks,"We consider a class of point processes (pp), which we call {\em sub-Poisson};
+these are pp that can be directionally-convexly ($dcx$) dominated by some
+Poisson pp. The $dcx$ order has already been shown useful in comparing various
+point process characteristics, including Ripley's and correlation functions as
+well as shot-noise fields generated by pp, indicating in particular that
+smaller in the $dcx$ order processes exhibit more regularity (less clustering,
+less voids) in the repartition of their points. Using these results, in this
+paper we study the impact of the $dcx$ ordering of pp on the properties of two
+continuum percolation models, which have been proposed in the literature to
+address macroscopic connectivity properties of large wireless networks. As the
+first main result of this paper, we extend the classical result on the
+existence of phase transition in the percolation of the Gilbert's graph (called
+also the Boolean model), generated by a homogeneous Poisson pp, to the class of
+homogeneous sub-Poisson pp. We also extend a recent result of the same nature
+for the SINR graph, to sub-Poisson pp. Finally, as examples we show that the
+so-called perturbed lattices are sub-Poisson. More generally, perturbed
+lattices provide some spectrum of models that ranges from periodic grids,
+usually considered in cellular network context, to Poisson ad-hoc networks, and
+to various more clustered pp including some doubly stochastic Poisson ones.",1009.5696v1
+2010-10-23,Closure method for spatially averaged dynamics of particle chains,"We study the closure problem for continuum balance equations that model
+mesoscale dynamics of large ODE systems. The underlying microscale model
+consists of classical Newton equations of particle dynamics. As a mesoscale
+model we use the balance equations for spatial averages obtained earlier by a
+number of authors: Murdoch and Bedeaux, Hardy, Noll and others. The momentum
+balance equation contains a flux (stress), which is given by an exact function
+of particle positions and velocities. We propose a method for approximating
+this function by a sequence of operators applied to average density and
+momentum. The resulting approximate mesoscopic models are systems in closed
+form. The closed from property allows one to work directly with the mesoscale
+equaitons without the need to calculate underlying particle trajectories, which
+is useful for modeling and simulation of large particle systems. The proposed
+closure method utilizes the theory of ill-posed problems, in particular
+iterative regularization methods for solving first order linear integral
+equations. The closed from approximations are obtained in two steps. First, we
+use Landweber regularization to (approximately) reconstruct the interpolants of
+relevant microscale quantitites from the average density and momentum. Second,
+these reconstructions are substituted into the exact formulas for stress. The
+developed general theory is then applied to non-linear oscillator chains. We
+conduct a detailed study of the simplest zero-order approximation, and show
+numerically that it works well as long as fluctuations of velocity are nearly
+constant.",1010.4832v1
+2010-10-26,Dualities and Identities for Entanglement-Assisted Quantum Codes,"The dual of an entanglement-assisted quantum error-correcting (EAQEC) code is
+the code resulting from exchanging the original code's information qubits with
+its ebits. To introduce this notion, we show how entanglement-assisted (EA)
+repetition codes and accumulator codes are dual to each other, much like their
+classical counterparts, and we give an explicit, general quantum shift-register
+circuit that encodes both classes of codes.We later show that our constructions
+are optimal, and this result completes our understanding of these dual classes
+of codes. We also establish the Gilbert-Varshamov bound and the Plotkin bound
+for EAQEC codes, and we use these to examine the existence of some EAQEC codes.
+Finally, we provide upper bounds on the block error probability when
+transmitting maximal-entanglement EAQEC codes over the depolarizing channel,
+and we derive variations of the hashing bound for EAQEC codes, which is a lower
+bound on the maximum rate at which reliable communication over Pauli channels
+is possible with the use of pre-shared entanglement.",1010.5506v4
+2010-11-12,"Magnetization Dynamics, Bennett Clocking and Associated Energy Dissipation in Multiferroic Logic","It has been recently shown that multiferroic logic - where logic bits are
+encoded in the magnetization orientation of a nanoscale magnetostrictive layer
+elastically coupled to a piezoelectric layer - can be Bennett clocked with
+small electrostatic potentials of few tens of mV applied to the piezoelectric
+layer. The potential generates stress in the magnetostrictive layer and rotates
+its magnetization by a large angle to carry out Bennett clocking. This method
+of clocking is far more energy-efficient than using spin transfer torque. In
+order to assess if such a clocking scheme can be also reasonably fast, we have
+studied the magnetization dynamics of a multiferroic logic array with nearest
+neighbor dipole coupling using the Landau-Lifshitz-Gilbert (LLG) equation. We
+find that switching delays of ~ 3 ns (clock rates of 0.33 GHz) can be achieved
+with proper design provided we clock non-adiabatically and dissipate ~48,000 kT
+(at room temperature) of energy per clock cycle per bit flip in the clocking
+circuit. This dissipation far exceeds the energy barrier separating the two
+logic states, which we assumed to be 32 kT to yield a bit error probability of
+. Had we used spin transfer torque to switch with the same ~ 3 ns delay, the
+energy dissipation would have been much larger (~ $6 \times 106$ kT). This
+shows that spin transfer torque, widely used in magnetic random access memory,
+is an inefficient way to switch a magnet, and multiferroic logic clocked with
+voltage-induced stress is a superior nanomagnetic logic scheme.",1011.2914v2
+2010-12-30,One-dimensional Gromov minimal filling,"The present paper opens a new branch in the theory of variational problems
+with branching extremals, the investigation of one-dimensional minimal fillings
+of finite pseudo-metric spaces. On the one hand, this problem is a
+one-dimensional version of a generalization of Gromov's minimal fillings
+problem to the case of stratified manifolds (the filling in our case is a
+weighted graph). On the other hand, this problem is interesting in itself and
+also can be considered as a generalization of another classical problem,
+namely, the Steiner problem on the construction of a shortest network joining a
+given set of terminals. Besides the statement of the problem, we discuss
+several properties of the minimal fillings, describe minimal fillings of
+additive spaces, and state several conjectures. We also include some
+announcements concerning the very recent results obtained in our group,
+including a formula calculating the weight of the minimal filling for an
+arbitrary finite pseudo-metric space and the concept of pseudo-additive space
+which generalizes the classical concept of additive space. We hope that the
+theory of one-dimensional minimal fillings refreshes the interest in the
+Steiner problem and gives an opportunity to solve several long standing
+problems, such as the calculation of the Steiner ratio, in particular the
+verification of the Gilbert--Pollack conjecture on the Steiner ratio of the
+Euclidean plane.",1101.0106v2
+2011-02-02,Kepler Input Catalog: Photometric Calibration and Stellar Classification,"We describe the photometric calibration and stellar classification methods
+used to produce the Kepler Input Catalog (KIC). The KIC is a catalog containing
+photometric and physical data for sources in the Kepler Mission field of view;
+it is used by the mission to select optimal targets. We derived atmospheric
+extinction corrections from hourly observations of secondary standard fields
+within the Kepler field of view. Repeatability of absolute photometry for stars
+brighter than magnitude 15 is typically 2%. We estimated stellar parameters
+Teff, log(g), log (Z), E_{B-V} using Bayesian posterior probability
+maximization to match observed colors to Castelli stellar atmosphere models. We
+applied Bayesian priors describing the distribution of solar-neighborhood stars
+in the color-magnitude diagram (CMD), in log (Z)$, and in height above the
+galactic plane. Comparisons with samples of stars classified by other means
+indicate that in most regions of the CMD, our classifications are reliable
+within about +/- 200 K and +/- 0.4 dex in log (g). It is difficult to assess
+the reliability of our log(Z) estimates, but there is reason to suspect that it
+is poor, particularly at extreme Teff. Of great importance for the Kepler
+Mission, for Teff <= 5400 K, the distinction between main-sequence stars and
+giants has proved to be reliable with better than 98% confidence. The KIC is
+available through the MAST data archive.",1102.0342v2
+2011-05-10,Interstellar Solid Hydrogen,"We consider the possibility that solid molecular hydrogen is present in
+interstellar space. If so cosmic-rays and energetic photons cause ionisation in
+the solid leading to the formation of H6+. This ion is not produced by
+gas-phase reactions and its radiative transitions therefore provide a signature
+of solid H2 in the astrophysical context. The vibrational transitions of H6+
+are yet to be observed in the laboratory, but we have characterised them in a
+quantum-theoretical treatment of the molecule; our calculations include
+anharmonic corrections, which are large. Here we report on those calculations
+and compare our results with astronomical data. In addition to the H6+
+isotopomer, we focus on the deuterated species (HD)3+ which is expected to
+dominate at low ionisation rates as a result of isotopic condensation
+reactions. We can reliably predict the frequencies of the fundamental bands for
+five modes of vibration. For (HD)3+ all of these are found to lie close to some
+of the strongest of the pervasive mid-infrared astronomical emission bands,
+making it difficult to exclude hydrogen precipitates on observational grounds.
+By the same token these results suggest that (HD)3+ could be the carrier of the
+observed bands. We consider this possibility within the broader picture of ISM
+photo-processes and we conclude that solid hydrogen may indeed be abundant in
+astrophysical environments.",1105.1861v1
+2011-05-12,The History of Star Formation in Galaxy Disks in the Local Volume as Measured by the ACS Nearby Galaxy Survey Treasury,"We present a measurement of the age distribution of stars residing in spiral
+disks and dwarf galaxies. We derive a complete star formation history of the
+~140 Mpc^3 covered by the volume-limited sample of galaxies in the Advanced
+Camera for Surveys (ACS) Nearby Galaxy Survey Treasury (ANGST). The total star
+formation rate density history is dominated by the large spirals in the volume,
+although the sample consists mainly of dwarf galaxies. Our measurement shows a
+factor of ~3 drop at z~2, in approximate agreement with results from other
+measurement techniques. While our results show that the overall star formation
+rate density has decreased since z~1, the measured rates during this epoch are
+higher than those obtained from other measurement techniques. This enhanced
+recent star formation rate appears to be largely due to an increase in the
+fraction of star formation contained in low-mass disks at recent times.
+Finally, our results indicate that despite the differences at recent times, the
+epoch of formation of ~50% of the stellar mass in dwarf galaxies was similar to
+that of ~50% of the stellar mass in large spiral galaxies (z>~2), despite the
+observed galaxy-to-galaxy diversity among the dwarfs.",1105.2571v1
+2011-06-30,Revisiting No-Scale Supergravity Inspired Scenarios: Updated Theoretical and Phenomenological Constraints,"We consider no-scale inspired supergravity scenarios, where the gravitino
+mass and related soft supersymmetry-breaking parameters are determined
+dynamically by radiative corrections to an essentially flat tree-level
+potential in the supersymmetry breaking hidden sector. We examine the
+theoretical and phenomenological viability of such a mechanism, when including
+up-to-date calculations of the low energy sparticle spectrum and taking into
+account the latest LHC results and other experimental constraints. We
+(re)emphasize the role of the scale-dependent vacuum energy contribution to the
+effective potential, in obtaining realistic no-scale electroweak minima,
+examining carefully the impact of boundary conditions and of variants of the
+minimization procedure. We also discuss and implement the B_0 (soft breaking
+Higgs mixing parameter) input boundary condition at high scale, therefore
+fixing tan beta(B_0) at low scales. For general high scale boundary conditions
+with non-vanishing B_0, m_0..., our analysis provides theoretical correlations
+among the supersymmetric, soft and vacuum energy parameters and related
+phenomenological consequences at the LHC. For instance, a zero vacuum energy at
+the GUT scale would lead to a decoupled supersymmetric spectrum, together with
+a light standard model-like Higgs boson at the electroweak scale. Given the
+experimental exclusion limits, a substantial class of the boundary conditions,
+and in particular the strict no-scale with m_0=A_0=B_0=0, are only compatible
+with a stau being the lightest MSSM particle. Then an enlarged allowed
+parameter space emerges when assuming a gravitino LSP to account for the
+observed dark matter relic density.",1106.6325v2
+2012-02-21,Making Evildoers Pay: Resource-Competitive Broadcast in Sensor Networks,"Consider a time-slotted, single-hop, wireless sensor network (WSN) consisting
+of n correct devices and and t=f*n Byzantine devices where f>=0 is any
+constant; that is, the Byzantine devices may outnumber the correct ones. There
+exists a trusted sender Alice who wishes to deliver a message m over a single
+channel to the correct devices. There also exists a malicious user Carol who
+controls the t Byzantine devices and uses them to disrupt the communication
+channel. For a constant k>=2, the correct and Byzantine devices each possess a
+meager energy budget of O(n^{1/k}), Alice and Carol each possess a limited
+budget of \tilde{O}(n^{1/k}), and sending or listening in a slot incurs unit
+cost. This general setup captures the inherent challenges of guaranteeing
+communication despite scarce resources and attacks on the network. Given this
+Alice versus Carol scenario, we ask: Is communication of m feasible and, if so,
+at what cost?
+  We develop a protocol which, for an arbitrarily small constant \epsilon>0,
+ensures that at least (1-\epsilon)n correct devices receive m with high
+probability. Furthermore, if Carol's devices expend T energy jamming the
+channel, then Alice and the correct devices each spend only
+\tilde{O}(T^{1/(k+1)}). In other words, delaying the transmission of m forces a
+jammer to rapidly deplete its energy supply and, consequently, cease attacks on
+the network.",1202.4576v4
+2012-03-28,Bispectrum of the Sunyaev-Zel'dovich Effect,"We perform a detailed study of the bispectrum of the Sunyaev-Zel'dovich
+effect. Using an analytical model for the pressure profiles of the intracluster
+medium, we demonstrate the SZ bispectrum to be a sensitive probe of the
+amplitude of the matter power spectrum parameter sigma_8. We find that the
+bispectrum amplitude scales as B_SZ ~ sigma_8^{11-12}, compared to that of the
+power spectrum, which scales as A_tSZ ~ sigma_8^{7-9}. We show that the SZ
+bispectrum is principally sourced by massive clusters at redshifts around
+z~0.4, which have been well-studied observationally. This is in contrast to the
+SZ power spectrum, which receives a significant contribution from less-well
+understood low-mass and high-redshift groups and clusters. Therefore, the
+amplitude of the bispectrum at l~3000 is less sensitive to astrophysical
+uncertainties than the SZ power spectrum. We show that current high resolution
+CMB experiments should be able to detect the SZ bispectrum amplitude with high
+significance, in part due to the low contamination from extra-galactic
+foregrounds. A combination of the SZ bispectrum and the power spectrum can
+sharpen the measurements of thermal and kinetic SZ components and help
+distinguish cosmological and astrophysical information from high-resolution CMB
+maps.",1203.6368v3
+2012-05-01,A quasi-analytical model for energy-delay-reliability tradeoff studies during write operations in perpendicular STT-RAM cell,"One of the biggest challenges the current STT-RAM industry faces is
+maintaining a high thermal stability while trying to switch within a given
+voltage pulse and energy cost. In this paper, we present a physics based
+analytical model that uses a modified Simmons' tunneling expression to capture
+the spin dependent tunneling in a magnetic tunnel junction(MTJ). Coupled with
+an analytical derivation of the critical switching current based on the
+Landau-Lifshitz-Gilbert equation, and the write error rate derived from a
+solution to the Fokker-Planck equation, this model provides us a quick estimate
+of the energydelay- reliability tradeoffs in perpendicular STTRAMs due to
+thermal fluctuations. In other words, the model provides a simple way to
+calculate the energy consumed during a write operation that ensures a certain
+error rate and delay time, while being numerically far less intensive than a
+full-fledged stochastic calculation. We calculate the worst case energy
+consumption during anti-parallel (AP) to parallel (P) and P to AP switchings
+and quantify how increasing the anisotropy field HK and lowering the saturation
+magnetization MS, can significantly reduce the energy consumption. A case study
+on how manufacturing variations of the MTJ cell can affect the energy
+consumption and delay is also reported.",1205.0183v1
+2012-05-16,Transients in porous media: asymptotic time-domain Green functions and limits of current frequency-domain models,"Time domain responses of porous media have been studied by some authors, but
+generally the possible descriptions have been given in the frequency domain.
+The aim of this paper, limited to materials with rigid skeleton considered as
+equivalent fluids, is to compare the descriptions by Johnson-Allard ($JA$%) as
+well as by Pride-Lafarge ($PL$) with i) some analytical, approximate formulas,
+based upon asymptotic high frequency expansion ; ii) the exact formula by
+Zwikker and Kosten for the case of cylindrical pores. The paper starts with a
+short summary of the statement of the different general full frequency models
+($JA$ and $PL).$ The Green function in the time domain is shown to exhibit
+interesting properties of materials. In particular the maximum response depends
+on one dimensionless parameter only, which is denoted $\xi $ and is the ratio
+of the travelled distance to the product of the \textquotedblleft
+frozen\textquotedblright\ sound speed and a characteristic viscous relaxation
+time. The distance $\xi $ is related to a time domain Stokes number. The
+numerical computation of the Green function is done by FFT, with some
+precautions, because of the importance of the higher frequencies on the
+response shape. The $PL$ description is shown to be the best full frequency
+general model, but some discrepancies with the exact model appear at short
+times or short distances. When the distance $\xi $ increases from zero, the
+asymptotic expansion shows that the maximum of the Green function decreases
+first as $1/\xi ^{2}$, then exponentially.",1205.3775v2
+2012-05-20,Externally-driven transformations of vortex textures in flat submicrometer magnets,"Two effects of oscillatory transformations of vortex textures in flat
+nanomagnets due to the application of an external field or a spin-polarized
+electric current are analytically described with relevance to soft-magnetic
+structures of submicrometer sizes (whose thickness is significantly bigger than
+the magnetostatic exchange length). These are changes of a domain wall (DW)
+structure in a long magnetic stripe (oscillations between a transverse DW, a
+vortex DW, and an antivortex DW) and periodic vortex-core reversals in a
+circular magnetic dot which are accompanied by oscillatory displacements of the
+vortex from the dot center. In nanostructures of smaller thicknesses
+(comparable to the exchange length), where nonlocal magnetostatic effects are
+very strong because of fast spatial variation of the magnetization, similar
+phenomena have been widely studied previously. Here, the dynamics is
+investigated within a local approach including magnetostatic field via boundary
+conditions on solutions to the Landau-Lifshitz-Gilbert equation only. Both the
+DWs in stripes and vortex states of the dot are treated as fragments of a
+cross-tie DW. Despite similarity of the cyclic transformations of the ordering
+to the dynamics of more strongly confined nanomagnets, details of motion
+(trajectories) of the vortices and antivortices (Bloch lines) of the textures
+under study are different, which is related to prohibition of rapid jumps of
+the polarization of Bloch lines. In addition to the magnetization rotation
+about the direction of magnetic field or current polarization, the evolution of
+textures is shown to relate to oscillatory changes of the direction of a
+cross-tie DW with respect to any arbitrary axis in the magnet plane accompanied
+by oscillations of the DW width.",1205.5008v1
+2012-06-11,Multi-Gigabit Wireless data transfer at 60 GHz,"In this paper we describe the status of the first prototype of the 60 GHz
+wireless Multi-gigabit data transfer topology currently under development at
+University of Heidelberg using IBM 130 nm SiGe HBT BiCMOS technology. The 60
+GHz band is very suitable for high data rate and short distance applications as
+for example needed in the HEP experments. The wireless transceiver consist of a
+transmitter and a receiver. The transmitter includes an On-Off Keying (OOK)
+modulator, an Local Oscillator (LO), a Power Amplifier (PA) and a BandPass
+Filter (BPF). The receiver part is composed of a BandPass- Filter (BPF), a Low
+Noise Amplifier (LNA), a double balanced down-convert Gilbert mixer, a Local
+Oscillator (LO), then a BPF to remove the mixer introduced noise, an
+Intermediate Amplifier (IF), an On-Off Keying demodulator and a limiting
+amplifier. The first prototype would be able to handle a data-rate of about 3.5
+Gbps over a link distance of 1 m. The first simulations of the LNA show that a
+Noise Figure (NF) of 5 dB, a power gain of 21 dB at 60 GHz with a 3 dB
+bandwidth of more than 20 GHz with a power consumption 11 mW are achieved.
+Simulations of the PA show an output referred compression point P1dB of 19.7 dB
+at 60 GHz.",1206.2287v1
+2012-08-08,RMR-Efficient Randomized Abortable Mutual Exclusion,"Recent research on mutual exclusion for shared-memory systems has focused on
+""local spin"" algorithms. Performance is measured using the ""remote memory
+references"" (RMRs) metric. As common in recent literature, we consider a
+standard asynchronous shared memory model with N processes, which allows atomic
+read, write and compare-and-swap (short: CAS) operations.
+  In such a model, the asymptotically tight upper and lower bound on the number
+of RMRs per passage through the Critical Section is Theta(log N) for the
+optimal deterministic algorithms (see Yang and Anderson,1995, and Attiya,
+Hendler and Woelfel, 2008). Recently, several randomized algorithms have been
+devised that break the Omega(log N) barrier and need only o(log N) RMRs per
+passage in expectation (see Hendler and Woelfel, 2010, Hendler and Woelfel,
+2011, and Bender and Gilbert, 2011). In this paper we present the first
+randomized ""abortable"" mutual exclusion algorithm that achieves a
+sub-logarithmic expected RMR complexity. More precisely, against a weak
+adversary (which can make scheduling decisions based on the entire past
+history, but not the latest coin-flips of each process) every process needs an
+expected number of O(log N/ log log N) RMRs to enter end exit the critical
+section. If a process receives an abort-signal, it can abort an attempt to
+enter the critical section within a finite number of its own steps and by
+incurring O(log N/ log log N) RMRs.",1208.1723v1
+2012-08-16,QIRAL: A High Level Language for Lattice QCD Code Generation,"Quantum chromodynamics (QCD) is the theory of subnuclear physics, aiming at
+mod- eling the strong nuclear force, which is responsible for the interactions
+of nuclear particles. Lattice QCD (LQCD) is the corresponding discrete
+formulation, widely used for simula- tions. The computational demand for the
+LQCD is tremendous. It has played a role in the history of supercomputers, and
+has also helped defining their future. Designing efficient LQCD codes that
+scale well on large (probably hybrid) supercomputers requires to express many
+levels of parallelism, and then to explore different algorithmic solutions.
+While al- gorithmic exploration is the key for efficient parallel codes, the
+process is hampered by the necessary coding effort. We present in this paper a
+domain-specific language, QIRAL, for a high level expression of parallel
+algorithms in LQCD. Parallelism is expressed through the mathematical struc-
+ture of the sparse matrices defining the problem. We show that from these
+expressions and from algorithmic and preconditioning formulations, a parallel
+code can be automatically generated. This separates algorithms and mathematical
+formulations for LQCD (that be- long to the field of physics) from the
+effective orchestration of parallelism, mainly related to compilation and
+optimization for parallel architectures.",1208.4035v1
+2012-08-22,Entanglement Spectrum Classification of $C_n$-invariant Noninteracting Topological Insulators in Two Dimensions,"We study the single particle entanglement spectrum in 2D topological
+insulators which possess $n$-fold rotation symmetry. By defining a series of
+special choices of subsystems on which the entanglement is calculated, or real
+space cuts, we find that the number of protected in-gap states for each type of
+these real space cuts is a quantum number indexing (if any) non-trivial
+topology in these insulators. We explicitly show the number of protected in-gap
+states is determined by a $Z^n$-index, $(z_1,...,z_n)$, where $z_m$ is the
+number of occupied states that transform according to $m$-th one-dimensional
+representation of the $C_n$ point group. We find that the entanglement spectrum
+contains in-gap states pinned in an interval of entanglement eigenvalues
+$[1/n,1-1/n]$. We determine the number of such in-gap states for an exhaustive
+variety of cuts, in terms of the $Z_m$ quantum numbers. Furthermore, we show
+that in a homogeneous system, the $Z^n$ index can be determined through an
+evaluation of the eigenvalues of point group symmetry operators at all
+high-symmetry points in the Brillouin zone. When disordered $n$-fold
+rotationally symmetric systems are considered, we find that the number of
+protected in-gap states is identical to that in the clean limit as long as the
+disorder preserves the underlying point group symmetry and does not close the
+bulk insulating gap.",1208.4603v1
+2012-09-25,Multiscale modeling in micromagnetics: existence of solutions and numerical integration,"Various applications ranging from spintronic devices, giant magnetoresistance
+sensors, and magnetic storage devices, include magnetic parts on very different
+length scales. Since the consideration of the Landau-Lifshitz-Gilbert equation
+(LLG) constrains the maximum element size to the exchange length within the
+media, it is numerically not attractive to simulate macroscopic parts with this
+approach. On the other hand, the magnetostatic Maxwell equations do not
+constrain the element size, but cannot describe the short-range exchange
+interaction accurately. A combination of both methods allows to describe
+magnetic domains within the micromagnetic regime by use of LLG and also
+considers the macroscopic parts by a non-linear material law using the Maxwell
+equations. In our work, we prove that under certain assumptions on the
+non-linear material law, this multiscale version of LLG admits weak solutions.
+Our proof is constructive in the sense that we provide a linear-implicit
+numerical integrator for the multiscale model such that the numerically
+computable finite element solutions admit weak $H^1$-convergence (at least for
+a subsequence) towards a weak solution.",1209.5548v2
+2012-10-05,"Rapid Size-Controlled Synthesis of Dextran-Coated, 64Cu-Doped Iron Oxide Nanoparticles","Research into developing dual modality probes enabled for magnetic resonance
+imaging (MRI) and positron emission tomography (PET) has been on the rise
+recently due to the potential to combine the high resolution of MRI and the
+high sensitivity of PET. Current synthesis techniques for developing multimodal
+probes is largely hindered in part by prolonged reaction times during
+radioisotope incorporation - leading to a weakening of the radioactivity. Along
+with a time-efficient synthesis, the resulting products must fit within a
+critical size range (between 20-100nm) to increase blood retention time. In
+this work, we describe a novel, rapid, microwave-based synthesis technique to
+grow dextran-coated iron oxide nanoparticles doped with copper (DIO/Cu).
+Traditional methods for coprecipitation of dextran-coated iron oxide
+nanoparticles require refluxing for 2 hours and result in approximately 50 nm
+diameter particles. We demonstrate that microwave synthesis can produce 50 nm
+nanoparticles with 5 minutes of heating. We discuss the various parameters used
+in the microwave synthesis protocol to vary the size distribution of DIO/Cu,
+and demonstrate the successful incorporation of 64Cu into these particles with
+the aim of future use for dual-mode MR/PET imaging.",1210.1823v1
+2012-10-05,Rapid Microwave-Assisted Synthesis of Dextran-Coated Iron Oxide Nanoparticles for Magnetic Resonance Imaging,"Currently, magnetic iron oxide nanoparticles are the only nano-sized magnetic
+resonance imaging (MRI) contrast agents approved for clinical use, yet
+commercial manufacturing of these agents has been limited or discontinued.
+Though there is still widespread demand for these particles both for clinical
+use and research, they are difficult to obtain commercially, and complicated
+syntheses make in-house preparation infeasible for most biological research
+labs or clinics. To make commercial production viable and increase
+accessibility of these products, it is crucial to develop simple, rapid, and
+reproducible preparations of biocompatible iron oxide nanoparticles. Here, we
+report a rapid, straightforward microwave-assisted synthesis of
+superparamagnetic dextran-coated iron oxide nanoparticles. The nanoparticles
+were produced in two hydrodynamic sizes with differing core morphologies by
+varying the synthetic method as either a two-step or single step process. A
+striking benefit of these methods is the ability to obtain swift and consistent
+results without the necessity for air, pH, or temperature sensitive techniques;
+therefore, reaction times and complex manufacturing processes are greatly
+reduced as compared to conventional synthetic methods. This is a great benefit
+for cost-effective translation to commercial production. The nanoparticles are
+found to be superparamagnetic and exhibit properties consistent for use in MRI.
+In addition, the dextran coating imparts the water-solubility and
+biocompatibility necessary for in vivo utilization.",1210.1827v1
+2012-10-16,Dark Matter Substructure Detection Using Spatially Resolved Spectroscopy of Lensed Dusty Galaxies,"We investigate how strong lensing of dusty, star-forming galaxies by
+foreground galaxies can be used as a probe of dark matter halo substructure. We
+find that spatially resolved spectroscopy of lensed sources allows dramatic
+improvements to measurements of lens parameters. In particular we find that
+modeling of the full, three-dimensional (angular position and radial velocity)
+data can significantly facilitate substructure detection, increasing the
+sensitivity of observables to lower mass subhalos. We carry out simulations of
+lensed dusty sources observed by early ALMA (Cycle 1) and use a Fisher matrix
+analysis to study the parameter degeneracies and mass detection limits of this
+method. We find that, even with conservative assumptions, it is possible to
+detect galactic dark matter subhalos of ~ 10^8 M_{\odot} with high significance
+in most lensed DSFGs. Specifically, we find that in typical DSFG lenses, there
+is a ~ 55 % probability of detecting a substructure with M>10^8 M_{\odot} with
+more than 5 sigma detection significance in each lens, if the abundance of
+substructure is consistent with previous lensing results. The full ALMA array,
+with its significantly enhanced sensitivity and resolution, should improve
+these estimates considerably. Given the sample of ~100 lenses provided by
+surveys like the South Pole Telescope, our understanding of dark matter
+substructure in typical galaxy halos is poised to improve dramatically over the
+next few years.",1210.4562v1
+2012-10-22,Shared Information -- New Insights and Problems in Decomposing Information in Complex Systems,"How can the information that a set ${X_{1},...,X_{n}}$ of random variables
+contains about another random variable $S$ be decomposed? To what extent do
+different subgroups provide the same, i.e. shared or redundant, information,
+carry unique information or interact for the emergence of synergistic
+information?
+  Recently Williams and Beer proposed such a decomposition based on natural
+properties for shared information. While these properties fix the structure of
+the decomposition, they do not uniquely specify the values of the different
+terms. Therefore, we investigate additional properties such as strong symmetry
+and left monotonicity. We find that strong symmetry is incompatible with the
+properties proposed by Williams and Beer. Although left monotonicity is a very
+natural property for an information measure it is not fulfilled by any of the
+proposed measures.
+  We also study a geometric framework for information decompositions and ask
+whether it is possible to represent shared information by a family of posterior
+distributions.
+  Finally, we draw connections to the notions of shared knowledge and common
+knowledge in game theory. While many people believe that independent variables
+cannot share information, we show that in game theory independent agents can
+have shared knowledge, but not common knowledge. We conclude that intuition and
+heuristic arguments do not suffice when arguing about information.",1210.5902v1
+2012-10-23,Lensing Noise in mm-wave Galaxy Cluster Surveys,"We study the effects of gravitational lensing by galaxy clusters of the
+background of dusty star-forming galaxies (DSFGs) and the Cosmic Microwave
+Background (CMB), and examine the implications for Sunyaev-Zel'dovich-based
+(SZ) galaxy cluster surveys. At the locations of galaxy clusters, gravitational
+lensing modifies the probability distribution of the background flux of the
+DSFGs as well as the CMB. We find that, in the case of a single-frequency 150
+GHz survey, lensing of DSFGs leads to both a slight increase (~10%) in detected
+cluster number counts (due to a ~ 50% increase in the variance of the DSFG
+background, and hence an increased Eddington bias), as well as to a rare
+(occurring in ~2% of clusters) ""filling-in"" of SZ cluster signals by bright
+strongly lensed background sources. Lensing of the CMB leads to a ~55%
+reduction in CMB power at the location of massive galaxy clusters in a
+spatially-matched single-frequency filter, leading to a net decrease in
+detected cluster number counts. We find that the increase in DSFG power and
+decrease in CMB power due to lensing at cluster locations largely cancel, such
+that the net effect on cluster number counts for current SZ surveys is
+sub-dominant to Poisson errors.",1210.6354v1
+2012-10-29,Spin-Transfer Torque Magnetization Reversal in Uniaxial Nanomagnets with Thermal Noise,"We consider the general Landau-Lifshitz-Gilbert (LLG) dynamical theory
+underlying the magnetization switching rates of a thin film uniaxial magnet
+subject to spin-torque effects and thermal fluctuations (thermal noise). After
+discussing the various dynamical regimes governing the switching phenomena, we
+present analytical results for the mean switching time behavior. Our approach,
+based on explicitly solving the first passage time problem, allows for a
+straightforward analysis of the thermally assisted, low spin-torque, switching
+asymptotics of thin film magnets. To verify our theory, we have developed an
+efficient GPU-based micromagnetic code to simulate the stochastic LLG dynamics
+out to millisecond timescales. We explore the effects of geometrical tilts
+between the spin-current and uniaxial anisotropy axes on the thermally assisted
+dynamics. We find that even in the absence of axial symmetry, the switching
+times can be functionally described in a form virtually identical to the
+collinear case. We further verify that asymptotic behavior is reached fairly
+slowly, thus quantifying the role of thermal noise in the crossover regime
+linking deterministic to thermally assisted magnetization reversal.",1210.7675v3
+2012-12-06,Splittings and automorphisms of relatively hyperbolic groups,"We study automorphisms of a relatively hyperbolic group G. When G is
+one-ended, we describe Out(G) using a preferred JSJ tree over subgroups that
+are virtually cyclic or parabolic. In particular, when G is toral relatively
+hyperbolic, Out(G) is virtually built out of mapping class groups and subgroups
+of GL_n(Z) fixing certain basis elements. When more general parabolic groups
+are allowed, these subgroups of GL_n(Z) have to be replaced by McCool groups:
+automorphisms of parabolic groups acting trivially (i.e. by conjugation) on
+certain subgroups. Given a malnormal quasiconvex subgroup P of a hyperbolic
+group G, we view G as hyperbolic relative to P and we apply the previous
+analysis to describe the group Out(P to G) of automorphisms of P that extend to
+G: it is virtually a McCool group. If Out(P to G) is infinite, then P is a
+vertex group in a splitting of G. If P is torsion-free, then Out(P to G) is of
+type VF, in particular finitely presented. We also determine when Out(G) is
+infinite, for G relatively hyperbolic. The interesting case is when G is
+infinitely-ended and has torsion. When G is hyperbolic, we show that Out(G) is
+infinite if and only if G splits over a maximal virtually cyclic subgroup with
+infinite center. In general we show that infiniteness of Out(G) comes from the
+existence of a splitting with infinitely many twists, or having a vertex group
+that is maximal parabolic with infinitely many automorphisms acting trivially
+on incident edge groups.",1212.1434v3
+2013-01-23,"Localization, metabelian groups, and the isomorphism problem","If G and H are finitely generated, residually nilpotent metabelian groups, H
+is termed para-G if there is a homomorphism of G into H which induces an
+isomorphism between the corresponding terms of their lower central quotient
+groups. We prove that this is an equivalence relation. It is a much coarser
+relation than isomorphism, our ultimate concern. It turns out that many of the
+groups in a given equivalence class share various properties including finite
+presentability. There are examples, such as the lamplighter group, where an
+equivalence class consists of a single isomorphism class and others where this
+is not the case. We give several examples where we solve the Isomorphism
+Problem. We prove also that the sequence of torsion-free ranks of the lower
+central quotients of a finitely generated metabelian group is computable. In a
+future paper we plan on proving that there is an algorithm to compute the
+numerator and denominator of the rational Poincar\'e series of a finitely
+generated metabelian group and will carry out this computation in a number of
+examples, which may shed a tiny bit of light on the Isomorphism Problem. Our
+proofs use localization, class field theory and some constructive commutative
+algebra.",1301.5533v2
+2013-01-26,Crystal nucleation and near-epitaxial growth in nacre,"Nacre is a layered, iridescent lining found inside many mollusk shells, with
+a unique brick-and-mortar periodic structure at the sub-micron scale, and
+remarkable resistance to fracture. Despite extensive studies, it remains
+unclear how nacre forms. Here we present 20-nm, 2{\deg}-resolution
+Polarization-dependent Imaging Contrast (PIC) images of shells from 15 mollusk
+shell species, mapping nacre tablets and their orientation patterns, showing
+where new crystal orientations appear and how they propagate across organic
+sheets as nacre grows. In all shells we found stacks of co-oriented aragonite
+(CaCO3) tablets arranged into vertical columns or staggered diagonally. Only
+near the nacre-prismatic boundary are disordered crystals nucleated, as
+spherulitic aragonite. Overgrowing nacre tablet crystals are most frequently
+co-oriented with the underlying spherulitic aragonite or with another tablet,
+connected by mineral bridges. Therefore aragonite crystal growth in nacre is
+epitaxial or near-epitaxial, with abrupt or gradual changes in orientation,
+with c-axes within 20{\deg}. Based on these data, we propose that there is one
+mineral bridge per tablet, and that ""bridge-tilting"" is a possible mechanism to
+introduce small, gradual or abrupt changes in the orientation of crystals
+within a stack of tablets as nacre grows.",1301.6273v2
+2013-02-03,A generalization of variable elimination for separable inverse problems beyond least squares,"In linear inverse problems, we have data derived from a noisy linear
+transformation of some unknown parameters, and we wish to estimate these
+unknowns from the data. Separable inverse problems are a powerful
+generalization in which the transformation itself depends on additional unknown
+parameters and we wish to determine both sets of parameters simultaneously.
+When separable problems are solved by optimization, convergence can often be
+accelerated by elimination of the linear variables, a strategy which appears
+most prominently in the variable projection methods due to Golub, Pereyra, and
+Kaufman. Existing variable elimination methods require an explicit formula for
+the optimal value of the linear variables, so they cannot be used in problems
+with Poisson likelihoods, bound constraints, or other important departures from
+least squares.
+  To address this limitation, we propose a generalization of variable
+elimination in which standard optimization methods are modified to behave as
+though a variable has been eliminated. We verify that this approach is a proper
+generalization by using it to re-derive several existing variable elimination
+techniques. We then extend the approach to bound-constrained and Poissonian
+problems, showing in the process that many of the best features of variable
+elimination methods can be duplicated in our framework. Tests on difficult
+exponential sum fitting and blind deconvolution problems indicate that the
+proposed approach can have significant speed and robustness advantages over
+standard methods.",1302.0441v2
+2013-04-05,City versus wetland: Predicting urban growth in the Vecht area with a cellular automaton model,"There are many studies dealing with the protection or restoration of wetlands
+and the sustainable economic growth of cities as separate subjects. This study
+investigates the conflict between the two in an area where city growth is
+threatening a protected wetland area. We develop a stochastic cellular
+automaton model for urban growth and apply it to the Vecht area surrounding the
+city of Hilversum in the Netherlands, using topographic maps covering the past
+150 years. We investigate the dependence of the urban growth pattern on the
+values associated with the protected wetland and other types of landscape
+surrounding the city. The conflict between city growth and wetland protection
+is projected to occur before 2035, assuming full protection of the wetland. Our
+results also show that a milder protection policy, allowing some of the wetland
+to be sacrificed, could be beneficial for maintaining other valuable
+landscapes. This insight would be difficult to achieve by other analytical
+means. We conclude that even slight changes in usage priorities of landscapes
+can significantly affect the landscape distribution in near future. Our results
+also point to the importance of a protection policy to take the value of
+surrounding landscapes and the dynamic nature of urban areas into account.",1304.1609v1
+2013-04-22,Topological Insulators with Commensurate Antiferromagnetism,"We study the topological features of non-interacting insulators subject to an
+antiferromangetic (AFM) Zeeman field, or AFM insulators, the period of which is
+commensurate with the lattice period. These insulators can be classified by the
+presence/absence of an emergent anti-unitary symmetry: the combined operation
+of time-reversal and a lattice translation by vector $\mathbf{D}$. For AFM
+insulators that preserve this combined symmetry, regardless of any details in
+lattice structure or magnetic structure, we show that (i) there is a new type
+of Kramers' degeneracy protected by the combined symmetry; (ii) a new $Z_2$
+index may be defined for 3D AFM insulators, but not for those in lower
+dimensions and (iii) in 3D AFM insulators with a non-trivial $Z_2$ index, there
+are odd number of gapless surface modes if and only if the surface termination
+also preserves the combined symmetry, but the dispersion of surface states
+becomes highly anisotropic if the AFM propagation vector becomes small compared
+with the reciprocal lattice vectors. We numerically demonstrate the theory by
+calculating the spectral weight of the surface states of a 3D TI in the
+presence of AFM fields with different propagation vectors, which may be
+observed by ARPES in Bi$_2$Se$_3$ or Bi$_2$Te$_3$ with induced
+antiferromagnetism.",1304.6081v3
+2013-05-17,Spectral gap for stochastic energy exchange model with nonuniformly positive rate function,"We give a lower bound on the spectral gap for a class of stochastic energy
+exchange models. In 2011, Grigo et al. introduced the model and showed that,
+for a class of stochastic energy exchange models with a uniformly positive rate
+function, the spectral gap of an $N$-component system is bounded from below by
+a function of order $N^{-2}$. In this paper, we consider the case where the
+rate function is not uniformly positive. For this case, the spectral gap
+depends not only on $N$ but also on the averaged energy $\mathcal{E}$, which is
+the conserved quantity under the dynamics. Under some assumption, we obtain a
+lower bound of the spectral gap which is of order $C(\mathcal{E})N^{-2}$ where
+$C(\mathcal{E})$ is a positive constant depending on $\mathcal {E}$. As a
+corollary of the result, a lower bound of the spectral gap for the mesoscopic
+energy exchange process of billiard lattice studied by Gaspard and Gilbert [J.
+Stat. Mech. Theory Exp. 2008 (2008) p11021, J. Stat. Mech. Theory Exp. 2009
+(2009) p08020] and the stick process studied by Feng et al. [Stochastic
+Process. Appl. 66 (1997) 147-182] are obtained.",1305.4066v3
+2013-08-18,Layered Constructions for Low-Delay Streaming Codes,"We propose a new class of error correction codes for low-delay streaming
+communication. We consider an online setup where a source packet arrives at the
+encoder every $M$ channel uses, and needs to be decoded with a maximum delay of
+$T$ packets. We consider a sliding-window erasure channel --- $\cC(N,B,W)$ ---
+which introduces either up to $N$ erasures in arbitrary positions, or $B$
+erasures in a single burst, in any window of length $W$. When $M=1$, the case
+where source-arrival and channel-transmission rates are equal, we propose a
+class of codes --- MiDAS codes --- that achieve a near optimal rate. Our
+construction is based on a {\em layered} approach. We first construct an
+optimal code for the $\cC(N=1,B,W)$ channel, and then concatenate an additional
+layer of parity-check symbols to deal with $N>1$. When $M > 1$, the case where
+source-arrival and channel-transmission rates are unequal, we characterize the
+capacity when $N=1$ and $W \ge M(T+1),$ and for $N>1$, we propose a
+construction based on a layered approach. Numerical simulations over
+Gilbert-Elliott and Fritchman channel models indicate significant gains in the
+residual loss probability over baseline schemes. We also discuss the connection
+between the error correction properties of the MiDAS codes and their underlying
+column distance and column span.",1308.3827v1
+2013-08-31,Delay Minimization for Instantly Decodable Network Coding in Persistent Channels with Feedback Intermittence,"In this paper, we consider the problem of minimizing the multicast decoding
+delay of generalized instantly decodable network coding (G-IDNC) over
+persistent forward and feedback erasure channels with feedback intermittence.
+In such an environment, the sender does not always receive acknowledgement from
+the receivers after each transmission. Moreover, both the forward and feedback
+channels are subject to persistent erasures, which can be modelled by a two
+state (good and bad states) Markov chain known as Gilbert-Elliott channel
+(GEC). Due to such feedback imperfections, the sender is unable to determine
+subsequent instantly decodable packets combination for all receivers. Given
+this harsh channel and feedback model, we first derive expressions for the
+probability distributions of decoding delay increments and then employ these
+expressions in formulating the minimum decoding problem in such environment as
+a maximum weight clique problem in the G-IDNC graph. We also show that the
+problem formulations in simpler channel and feedback models are special cases
+of our generalized formulation. Since this problem is NP-hard, we design a
+greedy algorithm to solve it and compare it to blind approaches proposed in
+literature. Through extensive simulations, our adaptive algorithm is shown to
+outperform the blind approaches in all situations and to achieve significant
+improvement in the decoding delay, especially when the channel is highly
+persistent",1309.0145v2
+2013-09-06,Energy release from impacting prominence material following the 2011 June 7 eruption,"Solar filaments exhibit a range of eruptive-like dynamic activity, ranging
+from the full or partial eruption of the filament mass and surrounding magnetic
+structure as a coronal mass ejection (CME), to a fully confined or 'failed'
+eruption. On 2011 June 7, a dramatic partial eruption of a filament was
+observed by multiple instruments on SDO and STEREO. One of the interesting
+aspects of this event is the response of the solar atmosphere as non-escaping
+material falls inward under the influence of gravity. The impact sites show
+clear evidence of brightening in the observed EUV wavelengths due to energy
+release. Two plausible physical mechanisms explaining the brightening are
+considered: heating of the plasma due to the kinetic energy of impacting
+material compressing the plasma, or reconnection between the magnetic field of
+low-lying loops and the field carried by the impacting material. By analyzing
+the emission of the brightenings in several SDO/AIA wavelengths, and comparing
+the kinetic energy of the impacting material (7.6 x 10^26 - 5.8 x 10^27 ergs)
+to the radiative energy (1.9 x 10^25 - 2.5 x 10^26 ergs) we find the dominant
+mechanism of energy release involved in the observed brightening is plasma
+compression.",1309.1769v1
+2013-09-26,Constraints on a second planet in the WASP-3 system,"There have been previous hints that the transiting planet WASP-3 b is
+accompanied by a second planet in a nearby orbit, based on small deviations
+from strict periodicity of the observed transits. Here we present 17 precise
+radial velocity measurements and 32 transit light curves that were acquired
+between 2009 and 2011. These data were used to refine the parameters of the
+host star and transiting planet. This has resulted in reduced uncertainties for
+the radii and masses of the star and planet. The radial-velocity data and the
+transit times show no evidence for an additional planet in the system.
+Therefore, we have determined the upper limit on the mass of any hypothetical
+second planet, as a function of its orbital period.",1309.6733v1
+2013-09-28,Synthetic Multiferroic Interconnects for Magnetic Logic Circuits,"In this work, we consider the possibility of using synthetic multiferroics
+comprising piezoelectric and magnetostrictive materials as an interconnect for
+nano magnetic logic circuits. The proposed interconnect resembles a parallel
+plate capacitor filled with a piezoelectric, where one of the plates is made of
+a magnetoelastic material. The operation of the interconnect is based on the
+effect of stress-mediated anisotropy modulation, where an electric field
+applied across the piezoelectric material produces stress, which, in turn,
+affects the anisotropy field in the magnetostrictive material. We present the
+results of numerical modeling illustrating signal propagation through the
+interconnect. The model combines electric and magnetic parts, where the
+electric part describes the distribution of an electric field through the
+piezoelectric and the magnetic part describes the change of magnetization in
+the magnetoelastic layer. The model is based on the Landau-Lifshitz-Gilbert
+equation with the electric field dependent anisotropy term included. The
+utilization of the electro-magnetic coupling makes it possible to amplify
+magnetic signal during its propagation via energy conversion from the electric
+to magnetic domains. Potentially, synthetic multiferroic interconnects can be
+implemented in a variety of spin-based devices ensuring reliable and low-energy
+consuming data transmission. According to the estimates, the group velocity of
+magnetic signals may be up to 100 km/s with energy dissipation less than aJ per
+bit per 100nm. The fundamental limits and practical shortcoming of the proposed
+approach are also discussed.",1309.7399v1
+2013-10-01,Ionized Plasma and Neutral Gas Coupling in the Sun's Chromosphere and Earth's Ionosphere/Thermosphere,"We review our understanding of ionized plasma and neutral gas coupling in the
+weakly ionized, stratified, electromagnetically-permeated regions of the Sun's
+chromosphere and Earth's ionosphere/thermosphere. Using representative models
+for each environment we derive fundamental descriptions of the coupling of the
+constituent parts to each other and to the electric and magnetic fields, and we
+examine the variation in magnetization of the ionized component. Using these
+descriptions we compare related phenomena in the two environments, and discuss
+electric currents, energy transfer and dissipation. We present a coupled
+theoretical and numerical study of plasma instabilities in the two environments
+that serves as an example of how the chromospheric and ionospheric communities
+can further collaborate. We also suggest future collaborative studies that will
+help improve our understanding of these two different atmospheres which share
+many similarities, but have large disparities in key quantities.",1310.0405v4
+2013-11-13,Excitation of radial collective modes in a quantum dot: Beyond linear response,"We compare the response of five different models of two interacting electrons
+in a quantum dot to an external short lived radial excitation that is strong
+enough to excite the system well beyond the linear response regime. The models
+considered describe the Coulomb interaction between the electrons in different
+ways ranging from mean-field approaches to configuration interaction (CI)
+models, where the two-electron Hamiltonian is diagonalized in a large truncated
+Fock space. The radially symmetric excitation is selected in order to severely
+put to test the different approaches to describe the interaction and
+correlations of an electron system in a nonequilibrium state. As can be
+expected for the case of only two electrons none of the mean-field models can
+in full details reproduce the results obtained by the CI model. Nonetheless,
+some linear and nonlinear characteristics are reproduced reasonably well. All
+the models show activation of an increasing number of collective modes as the
+strength of the excitation is increased. By varying slightly the confinement
+potential of the dot we observe how sensitive the properties of the excitation
+spectrum are to the Coulomb interaction and its correlation effects. In order
+to approach closer the question of nonlinearity we solve one of the mean-field
+models directly in a nonlinear fashion without resorting to iterations.",1311.3252v2
+2013-11-20,"Neutron-induced dpa, transmutations, gas production, and helium embrittlement of fusion materials","In a fusion reactor materials will be subjected to significant fluxes of
+high-energy neutrons. As well as causing radiation damage, the neutrons also
+initiate nuclear reactions leading to changes in the chemical composition of
+materials (transmutation). Many of these reactions produce gases, particularly
+helium, which cause additional swelling and embrittlement of materials. This
+paper investigates, using a combination of neutron-transport and inventory
+calculations, the variation in displacements per atom (dpa) and helium
+production levels as a function of position within the high flux regions of a
+recent conceptual model for the ""next-step"" fusion device DEMO. Subsequently,
+the gas production rates are used to provide revised estimates, based on new
+density-functional-theory results, for the critical component lifetimes
+associated with the helium-induced grain-boundary embrittlement of materials.
+The revised estimates give more optimistic projections for the lifetimes of
+materials in a fusion power plant compared to a previous study, while at the
+same time indicating that helium embrittlement remains one of the most
+significant factors controlling the structural integrity of fusion power plant
+components.",1311.5079v1
+2013-12-19,The availability of research data declines rapidly with article age,"Policies ensuring that research data are available on public archives are
+increasingly being implemented at the government [1], funding agency [2-4], and
+journal [5,6] level. These policies are predicated on the idea that authors are
+poor stewards of their data, particularly over the long term [7], and indeed
+many studies have found that authors are often unable or unwilling to share
+their data [8-11]. However, there are no systematic estimates of how the
+availability of research data changes with time since publication. We therefore
+requested datasets from a relatively homogenous set of 516 articles published
+between 2 and 22 years ago, and found that availability of the data was
+strongly affected by article age. For papers where the authors gave the status
+of their data, the odds of a dataset being extant fell by 17% per year. In
+addition, the odds that we could find a working email address for the first,
+last or corresponding author fell by 7% per year. Our results reinforce the
+notion that, in the long term, research data cannot be reliably preserved by
+individual researchers, and further demonstrate the urgent need for policies
+mandating data sharing via public archives.",1312.5670v1
+2014-01-13,On List-decodability of Random Rank Metric Codes,"In the present paper, we consider list decoding for both random rank metric
+codes and random linear rank metric codes. Firstly, we show that, for arbitrary
+$0<R<1$ and $\epsilon>0$ ($\epsilon$ and $R$ are independent), if
+$0<\frac{n}{m}\leq \epsilon$, then with high probability a random rank metric
+code in $F_{q}^{m\times n}$ of rate $R$ can be list-decoded up to a fraction
+$(1-R-\epsilon)$ of rank errors with constant list size $L$ satisfying $L\leq
+O(1/\epsilon)$. Moreover, if $\frac{n}{m}\geq\Theta_R(\epsilon)$, any rank
+metric code in $F_{q}^{m\times n}$ with rate $R$ and decoding radius
+$\rho=1-R-\epsilon$ can not be list decoded in ${\rm poly}(n)$ time. Secondly,
+we show that if $\frac{n}{m}$ tends to a constant $b\leq 1$, then every
+$F_q$-linear rank metric code in $F_{q}^{m\times n}$ with rate $R$ and list
+decoding radius $\rho$ satisfies the Gilbert-Varsharmov bound, i.e., $R\leq
+(1-\rho)(1-b\rho)$. Furthermore, for arbitrary $\epsilon>0$ and any $0<\rho<1$,
+with high probability a random $F_q$-linear rank metric codes with rate
+$R=(1-\rho)(1-b\rho)-\epsilon$ can be list decoded up to a fraction $\rho$ of
+rank errors with constant list size $L$ satisfying $L\leq O(\exp(1/\epsilon))$.",1401.2693v2
+2014-01-30,Quantitative Decoding of Interactions in Tunable Nanomagnet Arrays Using First Order Reversal Curves,"To develop a full understanding of interactions in nanomagnet arrays is a
+persistent challenge, critically impacting their technological acceptance. This
+paper reports the experimental, numerical and analytical investigation of
+interactions in arrays of Co nanoellipses using the first-order reversal curve
+(FORC) technique. A mean-field analysis has revealed the physical mechanisms
+giving rise to all of the observed features: a shift of the non-interacting
+FORC-ridge at the low-H$_c$ end off the local coercivity H$_c$ axis; a stretch
+of the FORC-ridge at the high-H$_c$ end without shifting it off the H$_c$ axis;
+and a formation of a tilted edge connected to the ridge at the low-H$_c$ end.
+Changing from flat to Gaussian coercivity distribution produces a negative
+feature, bends the ridge, and broadens the edge. Finally, nearest neighbor
+interactions segment the FORC-ridge. These results demonstrate that the FORC
+approach provides a comprehensive framework to qualitatively and quantitatively
+decode interactions in nanomagnet arrays.",1401.7749v1
+2014-02-07,For-all Sparse Recovery in Near-Optimal Time,"An approximate sparse recovery system in $\ell_1$ norm consists of parameters
+$k$, $\epsilon$, $N$, an $m$-by-$N$ measurement $\Phi$, and a recovery
+algorithm, $\mathcal{R}$. Given a vector, $\mathbf{x}$, the system approximates
+$x$ by $\widehat{\mathbf{x}} = \mathcal{R}(\Phi\mathbf{x})$, which must satisfy
+$\|\widehat{\mathbf{x}}-\mathbf{x}\|_1 \leq
+(1+\epsilon)\|\mathbf{x}-\mathbf{x}_k\|_1$. We consider the 'for all' model, in
+which a single matrix $\Phi$, possibly 'constructed' non-explicitly using the
+probabilistic method, is used for all signals $\mathbf{x}$. The best existing
+sublinear algorithm by Porat and Strauss (SODA'12) uses $O(\epsilon^{-3}
+k\log(N/k))$ measurements and runs in time $O(k^{1-\alpha}N^\alpha)$ for any
+constant $\alpha > 0$.
+  In this paper, we improve the number of measurements to $O(\epsilon^{-2} k
+\log(N/k))$, matching the best existing upper bound (attained by super-linear
+algorithms), and the runtime to $O(k^{1+\beta}\textrm{poly}(\log
+N,1/\epsilon))$, with a modest restriction that $\epsilon \leq (\log k/\log
+N)^{\gamma}$, for any constants $\beta,\gamma > 0$. When $k\leq \log^c N$ for
+some $c>0$, the runtime is reduced to $O(k\textrm{poly}(N,1/\epsilon))$. With
+no restrictions on $\epsilon$, we have an approximation recovery system with $m
+= O(k/\epsilon \log(N/k)((\log N/\log k)^\gamma + 1/\epsilon))$ measurements.",1402.1726v2
+2014-03-11,Measuring the power spectrum of dark matter substructure using strong gravitational lensing,"In recent years, it has become possible to detect individual dark matter
+subhalos near images of strongly lensed extended background galaxies.
+Typically, only the most massive subhalos in the strong lensing region may be
+detected this way. In this work, we show that strong lenses may also be used to
+constrain the much more numerous population of lower mass subhalos that are too
+small to be detected individually. In particular, we show that the power
+spectrum of projected density fluctuations in galaxy halos can be measured
+using strong gravitational lensing. We develop the mathematical framework of
+power spectrum estimation, and test our method on mock observations. We use our
+results to determine the types of observations required to measure the
+substructure power spectrum with high significance. We predict that deep
+observations ($\sim10$ hours on a single target) with current facilities can
+measure this power spectrum at the $3\sigma$ level, with no apparent degeneracy
+with unknown clumpiness in the background source structure or fluctuations from
+detector noise. Upcoming ALMA measurements of strong lenses are capable of
+placing strong constraints on the abundance of dark matter subhalos and the
+underlying particle nature of dark matter.",1403.2720v3
+2014-03-14,Cosmological Spectral Deconvolution,"One of the main goals of modern observational cosmology is to map the large
+scale structure of the Universe. A potentially powerful approach for doing this
+would be to exploit three-dimensional spectral maps, i.e. the specific
+intensity of extragalactic light as a function of wavelength and direction on
+the sky, to measure spatial variations in the total extragalactic light
+emission and use these as a tracer of the clustering of matter. A main
+challenge is that the observed intensity as a function of wavelength is a
+convolution of the source luminosity density with the rest-frame spectral
+energy distribution. In this paper, we introduce the method of spectral
+deconvolution as a way to invert this convolution and extract the clustering
+information. We show how one can use observations of the mean and angular
+fluctuations of extragalactic light as a function of wavelength, assuming
+statistical isotropy, to reconstruct jointly the rest-frame spectral energy
+distribution of the sources and the source spatial density fluctuations. This
+method is more general than the well known line mapping technique as it does
+not rely on spectral lines in the emitted spectra. After introducing the
+general formalism, we discuss its implementation and limitations. This formal
+paper sets the stage for future more practical studies.",1403.3727v1
+2014-03-27,On the Performance of Short Block Codes over Finite-State Channels in the Rare-Transition Regime,"As the mobile application landscape expands, wireless networks are tasked
+with supporting different connection profiles, including real-time traffic and
+delay-sensitive communications. Among many ensuing engineering challenges is
+the need to better understand the fundamental limits of forward error
+correction in non-asymptotic regimes. This article characterizes the
+performance of random block codes over finite-state channels and evaluates
+their queueing performance under maximum-likelihood decoding. In particular,
+classical results from information theory are revisited in the context of
+channels with rare transitions, and bounds on the probabilities of decoding
+failure are derived for random codes. This creates an analysis framework where
+channel dependencies within and across codewords are preserved. Such results
+are subsequently integrated into a queueing problem formulation. For instance,
+it is shown that, for random coding on the Gilbert-Elliott channel, the
+performance analysis based on upper bounds on error probability provides very
+good estimates of system performance and optimum code parameters. Overall, this
+study offers new insights about the impact of channel correlation on the
+performance of delay-aware, point-to-point communication links. It also
+provides novel guidelines on how to select code rates and block lengths for
+real-time traffic over wireless communication infrastructures.",1403.7232v1
+2014-04-08,Cost-oblivious storage reallocation,"Databases need to allocate and free blocks of storage on disk. Freed blocks
+introduce holes where no data is stored. Allocation systems attempt to reuse
+such deallocated regions in order to minimize the footprint on disk. If
+previously allocated blocks cannot be moved, the problem is called the memory
+allocation problem, which is known to have a logarithmic overhead in the
+footprint.
+  This paper defines the storage reallocation problem, where previously
+allocated blocks can be moved, or reallocated, but at some cost. The algorithms
+presented here are cost oblivious, in that they work for a broad and reasonable
+class of cost functions, even when they do not know what the cost function is.
+  The objective is to minimize the storage footprint, that is, the largest
+memory address containing an allocated object, while simultaneously minimizing
+the reallocation costs. This paper gives asymptotically optimal algorithms for
+storage reallocation, in which the storage footprint is at most (1+epsilon)
+times optimal, and the reallocation cost is at most (1/epsilon) times the
+original allocation cost, which is also optimal. The algorithms are cost
+oblivious as long as the allocation/reallocation cost function is subadditive.",1404.2019v3
+2014-04-14,Magneto-photonic phenomena at terahertz frequencies,"Magneto-terahertz phenomena are the main focus of the thesis. This work
+started as supporting research for the science of an X-ray laser (SwissFEL).
+X-ray lasers have recently drawn great attention as an unprecedented tool for
+scientific research on the ultrafast scale..... To answer this fundamental
+question, we performed original numerical simulations using a coupled Landau-
+Lifshitz-Gilbert Maxwell model. ... Those requirements were the motivations for
+the experiments performed in the second part of the thesis. To shape the
+terahertz pulses, .... Regarding the field intensities, we followed two
+approaches. The first deals with field enhancement in nanoslits arrays. We
+designed a subwavelength structure characterized by simultaneous high field
+enhancement and high transmission at terahertz frequencies to suit nonlinear
+sources. The second approach depended on up-scaling the generation from
+laser-induced plasma by increasing the pump wavelengths. Numerical calculations
+have also brought to our attention the importance of linear magnetoterahertz
+effects. In particular, the simulations showed that the ultrafast dynamics
+could lead to significant rotation of the polarization plane of the triggering
+terahertz pulse. Motivated by this finding, we focused in the last part of the
+thesis on the linear effects. We performed three original studies coming out
+with first demonstrations of broadband non-reciprocal terahertz phase
+retarders, terahertz magnetic modulators, and the non-reciprocal terahertz
+isolators. In the first two experiments, we extended the unique properties of
+the magnetic liquids (Ferrofluids) to the terahertz regime. In the latter
+experiment, we used a permanent magnet (Ferrite) to experimentally show
+complete isolation (unidirectional transmission) of the terahertz waves.",1404.3764v1
+2014-05-13,The Star Formation Histories of Local Group Dwarf Galaxies II. Searching For Signatures of Reionization,"We search for signatures of reionization in the star formation histories
+(SFHs) of 38 Local Group dwarf galaxies (10$^4$ $<$ M$_{\star}$ $<$ 10$^9$
+M$_{\odot}$). The SFHs are derived from color-magnitude diagrams using archival
+Hubble Space Telescope/Wide Field Planetary Camera 2 imaging. Only five
+quenched galaxies (And V, And VI, And XIII, Leo IV, Hercules) are consistent
+with forming the bulk of their stars before reionization, when full
+uncertainties are considered. Observations of 13 of the predicted `true
+fossils' identified by Bovill & Ricotti show that only two (Hercules and Leo
+IV) indicate star formation quenched by reionization. However, both are within
+the virial radius of the Milky Way and evidence of tidal disturbance
+complicates this interpretation. We argue that the late-time gas capture
+scenario posited by Ricotti for the low mass, gas-rich, and star-forming fossil
+candidate Leo T is observationally indistinguishable from simple gas retention.
+Given the ambiguity between environmental effects and reionization, the best
+reionization fossil candidates are quenched low mass field galaxies (e.g., KKR
+25).",1405.3281v1
+2014-05-26,Constraints for the Progenitor Masses of 17 Historic Core-Collapse Supernovae,"Using resolved stellar photometry measured from archival HST imaging, we
+generate color-magnitude diagrams of the stars within 50 pc of the locations of
+historic core-collapse supernovae that took place in galaxies within 8 Mpc. We
+fit these color-magnitude distributions with stellar evolution models to
+determine the best-fit age distribution of the young population. We then
+translate these age distributions into probability distributions for the
+progenitor mass of each SNe. The measurements are anchored by the main-sequence
+stars surrounding the event, making them less sensitive to assumptions about
+binarity, post-main-sequence evolution, or circumstellar dust. We demonstrate
+that, in cases where the literature contains masses that have been measured
+from direct imaging, our measurements are consistent with (but less precise
+than) these measurements. Using this technique, we constrain the progenitor
+masses of 17 historic SNe, 11 of which have no previous estimates from direct
+imaging. Our measurements still allow the possibility that all SNe progenitor
+masses are <20 M_sun. However, the large uncertainties for the highest-mass
+progenitors also allow the possibility of no upper-mass cutoff.",1405.6626v1
+2014-06-09,"Calibrating CHIME, A New Radio Interferometer to Probe Dark Energy","The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a transit
+interferometer currently being built at the Dominion Radio Astrophysical
+Observatory (DRAO) in Penticton, BC, Canada. We will use CHIME to map neutral
+hydrogen in the frequency range 400 -- 800\,MHz over half of the sky, producing
+a measurement of baryon acoustic oscillations (BAO) at redshifts between 0.8 --
+2.5 to probe dark energy. We have deployed a pathfinder version of CHIME that
+will yield constraints on the BAO power spectrum and provide a test-bed for our
+calibration scheme. I will discuss the CHIME calibration requirements and
+describe instrumentation we are developing to meet these requirements.",1406.2267v1
+2014-07-10,Beating the Heat! Automated Characterization of Piezoelectric Tubes for Starbugs,"The Australian Astronomical Observatory has extensively prototyped a new
+robotic positioner to allow simultaneous positioning of optical fibers at the
+focal plane called 'Starbugs'. The Starbug devices each consist of two
+concentric piezoelectric tubes that 'walk' the optical fiber over the focal
+plane to accuracy of several microns. Ongoing research has led to the
+development of several Starbug prototypes, but lack of performance data has
+hampered further progress in the design of the Starbug positioners and the
+support equipment required to power and control them. Furthermore, Starbugs
+have been selected for the TAIPAN instrument, a prototype for MANIFEST on the
+GMT. A need now arises to measure and characterize 100's of piezoelectric tubes
+before full scale production of Starbugs for TAIPAN. The manual measurements of
+these piezoelectric tubes are a time consuming process taking several hours.
+Therefore, a versatile automated system is needed to measure and characterize
+these tubes in the laboratory before production of Starbugs. We have solved
+this problem with the design of an automated LabVIEW application that
+significantly reduces test times to several minutes. We present the various
+design aspects of the automation system and provide analyses of example
+piezoelectric tubes for Starbugs.",1407.2681v1
+2014-07-16,TriAnd and its Siblings: Satellites of Satellites in the Milky Way Halo,"We explore the Triangulum-Andromeda (TriAnd) overdensity in the SPLASH
+(Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo) and SEGUE
+(the Sloan Extension for Galactic Understanding and Exploration) spectroscopic
+surveys. Milky Way main sequence turn-off stars in the SPLASH survey reveal
+that the TriAnd overdensity and the recently discovered PAndAS stream (Martin
+et al. 2014) share a common heliocentric distance (D ~ 20 kpc), position on the
+sky, and line-of-sight velocity (V_GSR ~ 50 km/s). Similarly, A-type, giant,
+and main sequence turn-off stars selected from the SEGUE survey in the vicinity
+of the Segue 2 satellite show that TriAnd is prevalent in these fields, with a
+velocity and distance similar to Segue 2. The coincidence of the PAndAS stream
+and Segue 2 satellite in positional and velocity space to TriAnd suggests that
+these substructures are all associated, and may be a fossil record of
+group-infall onto the Milky Way halo. In this scenario, the Segue 2 satellite
+and PAndAS stream are ""satellites of satellites"", and the large, metal-rich
+TriAnd overdensity is the remains of the group central.",1407.4458v2
+2014-07-17,The Green's Function for the Hückel (Tight Binding) Model,"Applications of the H\""uckel (tight binding) model are ubiquitous in quantum
+chemistry and solid state physics. The matrix representation of this model is
+isomorphic to an unoriented vertex adjacency matrix of a bipartite graph, which
+is also the Laplacian matrix plus twice the identity. In this paper, we
+analytically calculate the determinant and, when it exists, the inverse of this
+matrix in connection with the Green's function, $\mathbf{G}$, of the $N\times
+N$ H\""uckel matrix. A corollary is a closed form expression for a Harmonic sum
+(Eq. 12). We then extend the results to $d-$dimensional lattices, whose linear
+size is $N$. The existence of the inverse becomes a question of number theory.
+We prove a new theorem in number theory pertaining to vanishing sums of cosines
+and use it to prove that the inverse exists if and only if $N+1$ and $d$ are
+odd and $d$ is smaller than the smallest divisor of $N+1$. We corroborate our
+results by demonstrating the entry patterns of the Green's function and discuss
+applications related to transport and conductivity.",1407.4780v4
+2014-07-29,Formation of magnetic skyrmions with tunable properties in PdFe bilayer deposited on Ir(111),"We perform an extensive study of the spin-configurations in a PdFe bilayer on
+Ir(111) in terms of ab initio and spin-model calculations. We use the
+spin-cluster expansion technique to obtain spin model parameters, and solve the
+Landau-Lifshitz-Gilbert equations at zero temperature. In particular, we focus
+on effects of layer relaxations and the evolution of the magnetic ground state
+in external magnetic field. In the absence of magnetic field, we find a
+spin-spiral ground state, while applying external magnetic field skyrmions are
+generated in the system. Based on energy calculations of frozen spin
+configurations with varying magnetic field we obtain excellent agreement for
+the phase boundaries with available experiments. We find that the wave length
+of spin-spirals and the diameter of skyrmions decrease with increasing inward
+Fe layer relaxation which is correlated with the increasing ratio of the
+nearest-neighbor Dzyaloshinskii-Moriya interaction and the isotropic exchange
+coupling, $D/J$. Our results also indicate that the applied field needed to
+stabilize the skyrmion lattice increases when the diameter of individual
+skyrmions decreases. Based on our observations, we suggest that the formation
+of the skyrmion lattice can be tuned by small structural modification of the
+thin film.",1407.7718v2
+2014-08-14,"Developing Structural, High-heat flux and Plasma Facing Materials for a near-term DEMO Fusion Power Plant: the EU Assessment","The findings of the EU 'Materials Assessment Group' (MAG), within the 2012 EU
+Fusion Roadmap exercise, are discussed. MAG analysed the technological
+readiness of structural, plasma facing and high heat flux materials for a DEMO
+concept to be constructed in the early 2030s, proposing a coherent strategy for
+R&D up to a DEMO construction decision. Technical consequences for the
+materials required and the development, testing and modelling programmes, are
+analysed using: a systems engineering approach, considering reactor operational
+cycles, efficient maintenance and inspection requirements, and interaction with
+functional materials/coolants; and a project-based risk analysis, with R&D to
+mitigate risks from material shortcomings including development of specific
+risk mitigation materials.",1408.3546v1
+2014-08-26,"Weedy adaptation in Setaria spp.: IX. Effects of salinity, temperature, light and seed dormancy on Setaria faberi seed germination","Life in salty habitats is a function of tolerance to those chemicals at all
+critical phases of a plant's life history. The ability to withstand salt as an
+established plant may require different mechanisms and plant traits than those
+needed to germinate in salty soils. Seeds establishing themselves in high salt
+content may respond differently depending on the light conditions and seed
+germinability at the time of salty water imbibition. S. faberi seed (and S.
+viridis and S. pumila) plants were discovered thriving along the seacoasts of
+Southern Japan. These plants possess the ability to after-ripen, germinate,
+emerge and establish themselves, grow and reproduce in the salty soils and
+salt-laden atmospheres present in these windy habitats. The objectives of this
+paper are to determine the effect of salt (NaCl) in water imbibed by S. faberi
+seed during after-ripening and germination, as well temperature and light.
+Observations made also provide insights on the possible relationship between
+salt and drought tolerance. Seed germination of all phenotypes inhibited by two
+percent or more of NaCl. The effects of lesser amounts of NaCl on each of the
+three phenotypes was highly dependent on the specific temperature and light
+conditions. The three test phenotypes provided a good range to detect responses
+to salinity, allowing the observation of both stimulatory and inhibitory
+responses.",1408.6187v1
+2014-09-02,Accessing Different Spin-Disordered States using First Order Reversal Curves,"Combined first order reversal curve (FORC) analyses of the magnetization
+(M-FORC) and magnetoresistance (MR-FORC) have been employed to provide a
+comprehensive study of the M-MR correlation in two canonical systems: a
+NiFe/Cu/FePt pseudo spin-valve (PSV) and a [Co/Cu]8 multilayer. In the PSV, due
+to the large difference in switching fields and minimal interactions between
+the NiFe and FePt layers, the M and MR show a simple one-to-one relationship
+during reversal. In the [Co/Cu]8 multilayer, the correlation between the
+magnetization reversal and MR evolution is more complex. This is primarily due
+to the similar switching fields of, and interactions between, the constituent
+Co layers. The FORC protocol accesses states with much higher spin disorders
+and larger MR than those found along the conventional major loop field-cycle.
+Unlike the M-FORC measurements, which only probe changes in the macroscopic
+magnetization, the MR-FORCs are more sensitive to the microscopic domain
+configurations, as those are most important in determining the resultant MR
+effect size. This approach is generally applicable to spintronic systems to
+realize the maximum spin-disorder and the largest MR.",1409.0825v1
+2014-10-20,Momentum space imaging of Cooper pairing in a half-Dirac-gas topological superconductor (a helical 2D topological superconductor),"Superconductivity in Dirac electrons has recently been proposed as a new
+platform between novel concepts in high-energy and condensed matter physics. It
+has been proposed that supersymmetry and exotic quasiparticles, both of which
+remain elusive in particle physics, may be realized as emergent particles in
+superconducting Dirac electron systems. Using artificially fabricated
+topological insulator-superconductor heterostructures, we present direct
+spectroscopic evidence for the existence of Cooper pairing in a half Dirac gas
+2D topological superconductor. Our studies reveal that superconductivity in a
+helical Dirac gas is distinctly different from that of in an ordinary
+two-dimensional superconductor while considering the spin degrees of freedom of
+electrons. We further show that the pairing of Dirac electrons can be
+suppressed by time-reversal symmetry breaking impurities removing the
+distinction. Our demonstration and momentum-space imaging of Cooper pairing in
+a half Dirac gas and its magnetic behavior taken together serve as a critically
+important 2D topological superconductor platform for future testing of novel
+fundamental physics predictions such as emergent supersymmetry and quantum
+criticality in topological systems.",1410.5405v1
+2014-12-23,Dynamical symmetries of Markov processes with multiplicative white noise,"We analyse various properties of stochastic Markov processes with
+multiplicative white noise. We take a single-variable problem as a simple
+example, and we later extend the analysis to the Landau-Lifshitz-Gilbert
+equation for the stochastic dynamics of a magnetic moment. In particular, we
+focus on the non-equilibrium transfer of angular momentum to the magnetization
+from a spin-polarised current of electrons, a technique which is widely used in
+the context of spintronics to manipulate magnetic moments. We unveil two hidden
+dynamical symmetries of the generating functionals of these Markovian
+multiplicative white-noise processes. One symmetry only holds in equilibrium
+and we use it to prove generic relations such as the fluctuation-dissipation
+theorems. Out of equilibrium, we take profit of the symmetry-breaking terms to
+prove fluctuation theorems. The other symmetry yields strong dynamical
+relations between correlation and response functions which can notably simplify
+the numerical analysis of these problems. Our construction allows us to clarify
+some misconceptions on multiplicative white-noise stochastic processes that can
+be found in the literature. In particular, we show that a first-order
+differential equation with multiplicative white noise can be transformed into
+an additive-noise equation, but that the latter keeps a non-trivial memory of
+the discretisation prescription used to define the former.",1412.7564v2
+2015-01-09,Random Triangle Theory with Geometry and Applications,"What is the probability that a random triangle is acute? We explore this old
+question from a modern viewpoint, taking into account linear algebra, shape
+theory, numerical analysis, random matrix theory, the Hopf fibration, and much
+much more. One of the best distributions of random triangles takes all six
+vertex coordinates as independent standard Gaussians. Six can be reduced to
+four by translation of the center to $(0,0)$ or reformulation as a 2x2 matrix
+problem.
+  In this note, we develop shape theory in its historical context for a wide
+audience. We hope to encourage other to look again (and differently) at
+triangles.
+  We provide a new constructive proof, using the geometry of parallelians, of a
+central result of shape theory: Triangle shapes naturally fall on a hemisphere.
+We give several proofs of the key random result: that triangles are uniformly
+distributed when the normal distribution is transferred to the hemisphere. A
+new proof connects to the distribution of random condition numbers.
+Generalizing to higher dimensions, we obtain the ""square root ellipticity
+statistic"" of random matrix theory.
+  Another proof connects the Hopf map to the SVD of 2 by 2 matrices. A new
+theorem describes three similar triangles hidden in the hemisphere. Many
+triangle properties are reformulated as matrix theorems, providing insight to
+both. This paper argues for a shift of viewpoint to the modern approaches of
+random matrix theory. As one example, we propose that the smallest singular
+value is an effective test for uniformity. New software is developed and
+applications are proposed.",1501.03053v1
+2015-02-03,The use of covariates and random effects in evaluating predictive biomarkers under a potential outcome framework,"Predictive or treatment selection biomarkers are usually evaluated in a
+subgroup or regression analysis with focus on the treatment-by-marker
+interaction. Under a potential outcome framework (Huang, Gilbert and Janes
+[Biometrics 68 (2012) 687-696]), a predictive biomarker is considered a
+predictor for a desirable treatment benefit (defined by comparing potential
+outcomes for different treatments) and evaluated using familiar concepts in
+prediction and classification. However, the desired treatment benefit is
+unobservable because each patient can receive only one treatment in a typical
+study. Huang et al. overcome this problem by assuming monotonicity of potential
+outcomes, with one treatment dominating the other in all patients. Motivated by
+an HIV example that appears to violate the monotonicity assumption, we propose
+a different approach based on covariates and random effects for evaluating
+predictive biomarkers under the potential outcome framework. Under the proposed
+approach, the parameters of interest can be identified by assuming conditional
+independence of potential outcomes given observed covariates, and a sensitivity
+analysis can be performed by incorporating an unobserved random effect that
+accounts for any residual dependence. Application of this approach to the
+motivating example shows that baseline viral load and CD4 cell count are both
+useful as predictive biomarkers for choosing antiretroviral drugs for
+treatment-naive patients.",1502.00757v1
+2015-02-03,The Blackhole-Dark Matter Halo Connection,"We explore the connection between the central supermassive blackholes (SMBH)
+in galaxies and the dark matter halo through the relation between the masses of
+the SMBHs and the maximum circular velocities of the host galaxies, as well as
+the relationship between stellar velocity dispersion of the spheroidal
+component and the circular velocity. Our assumption here is that the circular
+velocity is a proxy for the mass of the dark matter halo. We rely on a
+heterogeneous sample containing galaxies of all types. The only requirement is
+that the galaxy has a direct measurement of the mass of its SMBH and a direct
+measurement of its circular velocity and its velocity dispersion. Previous
+studies have analyzed the connection between the SMBH and dark matter halo
+through the relationship between the circular velocity and the bulge velocity
+dispersion, with the assumption that the bulge velocity dispersion stands in
+for the mass of the SMBH, via the well{}-established SMBH mass{}-bulge velocity
+dispersion relation. Using intermediate relations may be misleading when one is
+studying them to decipher the active ingredients of galaxy formation and
+evolution. We believe that our approach will provide a more direct probe of the
+SMBH and the dark matter halo connection. We find that the correlation between
+the mass of supermassive blackholes and the circular velocities of the host
+galaxies is extremely weak, leading us to state the dark matter halo may not
+play a major role in regulating the blackhole growth in the present Universe.",1502.00775v1
+2015-03-01,Computing in continuous space with self-assembling polygonal tiles,"In this paper we investigate the computational power of the polygonal tile
+assembly model (polygonal TAM) at temperature 1, i.e. in non-cooperative
+systems. The polygonal TAM is an extension of Winfree's abstract tile assembly
+model (aTAM) which not only allows for square tiles (as in the aTAM) but also
+allows for tile shapes that are polygons. Although a number of self-assembly
+results have shown computational universality at temperature 1, these are the
+first results to do so by fundamentally relying on tile placements in
+continuous, rather than discrete, space. With the square tiles of the aTAM, it
+is conjectured that the class of temperature 1 systems is not computationally
+universal. Here we show that the class of systems whose tiles are composed of a
+regular polygon P with n > 6 sides is computationally universal. On the other
+hand, we show that the class of systems whose tiles consist of a regular
+polygon P with n <= 6 cannot compute using any known techniques. In addition,
+we show a number of classes of systems whose tiles consist of a non-regular
+polygon with n >= 3 sides are computationally universal.",1503.00327v2
+2015-03-05,Nonparametric Bounds and Sensitivity Analysis of Treatment Effects,"This paper considers conducting inference about the effect of a treatment (or
+exposure) on an outcome of interest. In the ideal setting where treatment is
+assigned randomly, under certain assumptions the treatment effect is
+identifiable from the observable data and inference is straightforward.
+However, in other settings such as observational studies or randomized trials
+with noncompliance, the treatment effect is no longer identifiable without
+relying on untestable assumptions. Nonetheless, the observable data often do
+provide some information about the effect of treatment, that is, the parameter
+of interest is partially identifiable. Two approaches are often employed in
+this setting: (i) bounds are derived for the treatment effect under minimal
+assumptions, or (ii) additional untestable assumptions are invoked that render
+the treatment effect identifiable and then sensitivity analysis is conducted to
+assess how inference about the treatment effect changes as the untestable
+assumptions are varied. Approaches (i) and (ii) are considered in various
+settings, including assessing principal strata effects, direct and indirect
+effects and effects of time-varying exposures. Methods for drawing formal
+inference about partially identified parameters are also discussed.",1503.01598v1
+2015-03-16,Dynamics of Current and Field Driven Domain Wall Motion under the Influence of Transverse Magnetic Field,"The dynamics of transverse Neel domain wall in a ferromagnetic nanostrip in
+the presence of driving field, current and transverse magnetic field is
+investigated by the Landau-Lifshitz-Gilbert(LLG) equation with the adiabatic
+and non-adiabatic spin-transfer torques both analytically and numerically. The
+analytical expressions for the velocity, width, excitation angle and
+displacement for the domain wall are obtained by using small angle
+approximation along with Walkers trial function. The results show that the
+initial velocity of the domain wall can be controlled by the adiabatic
+spin-transfer torque and the saturated velocity can be controlled by the
+non-adiabatic spin-transfer torque and driving field. The large increase in the
+saturated velocity of the domain wall driven by current and field due to the
+transverse magnetic field is identified through the presence of driving field.
+There is no impact in the saturated velocity of the domain wall driven by
+current from the transverse magnetic field. For the domain wall driven by the
+current in the presence of the transverse magnetic field, the saturated
+velocity remains constant. The transverse magnetic field along with current and
+driving field is more advantageous that the transverse magnetic field along
+with current for increasing the saturated velocity of the domain wall. The
+numerical results showed that the saturated velocity is increased by the
+transverse magnetic field with the irrespective of the directions of the
+driving field and current further it is higher and lower when the directions of
+driving field and current are antiparallel and parallel respectively. The
+obtained analytical solutions are closely coincided with the computed numerical
+results.",1503.04560v2
+2015-03-17,Single Hit Energy-resolved Laue Diffraction,"In-situ white light Laue diffraction has been successfully used to
+interrogate the structure of single crystal materials undergoing rapid
+(nanosecond) dynamic compression up to megabar pressures. However, information
+on strain state accessible via this technique is limited, reducing its
+applicability for a range of applications. We present an extension to the
+existing Laue diffraction platform in which we record the photon energy of a
+subset of diffraction peaks. This allows for a measurement of the longitudinal
+and transverse strains in-situ during compression. Consequently, we demonstrate
+measurement of volumetric compression of the unit cell, in addition to the
+limited aspect ratio information accessible in conventional white light Laue.
+We present preliminary results for silicon, where only an elastic strain is
+observed. VISAR measurements show the presence of a two wave structure and
+measurements show that material downstream of the second wave does not
+contribute to the observed diffraction peaks, supporting the idea that this
+material may be highly disordered, or has undergone large scale rotation.",1503.05131v2
+2015-03-24,No variations in transit times for Qatar-1 b,"The transiting hot Jupiter planet Qatar-1 b was presented to exhibit
+variations in transit times that could be of perturbative nature. A hot Jupiter
+with a planetary companion on a nearby orbit would constitute an unprecedented
+planetary configuration, important for theories of formation and evolution of
+planetary systems. We performed a photometric follow-up campaign to confirm or
+refute transit timing variations. We extend the baseline of transit
+observations by acquiring 18 new transit light curves acquired with 0.6-2.0 m
+telescopes. These photometric time series, together with data available in the
+literature, were analyzed in a homogenous way to derive reliable transit
+parameters and their uncertainties. We show that the dataset of transit times
+is consistent with a linear ephemeris leaving no hint for any periodic
+variations with a range of 1 min. We find no compelling evidence for the
+existence of a close-in planetary companion to Qatar-1 b. This finding is in
+line with a paradigm that hot Jupiters are not components of compact
+multi-planetary systems. Based on dynamical simulations, we place tighter
+constraints on a mass of any fictitious nearby planet in the system.
+Furthermore, new transit light curves allowed us to redetermine system
+parameters with the precision better than that reported in previous studies.
+Our values generally agree with previous determinations.",1503.07191v1
+2015-03-25,Rigorous numerical study of strong microwave photon-magnon coupling in all-dielectric magnetic multilayers,"We demonstrate theoretically a strong local enhancement of the intensity of
+the in-plane microwave magnetic field in multilayered structures made from a
+magneto-insulating yttrium iron garnet (YIG) layer sandwiched between two
+non-magnetic layers with a high dielectric constant matching that of YIG. The
+enhancement is predicted for the excitation regime when the microwave magnetic
+field is induced inside the multilayer by the transducer of a stripline
+Broadband Ferromagnetic Resonance (BFMR) setup. By means of a rigorous
+numerical solution of the Landau-Lifshitz-Gilbert equation consistently with
+the Maxwell's equations, we investigate the magnetisation dynamics in the
+multilayer. We reveal a strong photon-magnon coupling, which manifests itself
+as anti-crossing of the ferromagnetic resonance (FMR) magnon mode supported by
+the YIG layer and the electromagnetic resonance mode supported by the whole
+multilayered structure. The frequency of the magnon mode depends on the
+external static magnetic field, which in our case is applied tangentially to
+the multilayer in the direction perpendicular to the microwave magnetic field
+induced by the stripline of the BFMR setup. The frequency of the
+electromagnetic mode is independent of the static magnetic field. Consequently,
+the predicted photon-magnon coupling is sensitive to the applied magnetic field
+and thus can be used in magnetically tuneable metamaterials based on
+simultaneously negative permittivity and permeability achievable thanks to the
+YIG layer. We also suggest that the predicted photon-magnon coupling may find
+applications in microwave quantum information systems.",1503.07282v1
+2015-04-22,Thermally Driven Ratchet Motion of Skyrmion Microcrystal and Topological Magnon Hall Effect,"Spontaneously emergent chirality is an issue of fundamental importance across
+the natural sciences. It has been argued that a unidirectional (chiral)
+rotation of a mechanical ratchet is forbidden in thermal equilibrium, but
+becomes possible in systems out of equilibrium. Here we report our finding that
+a topologically nontrivial spin texture known as a skyrmion - a particle-like
+object in which spins point in all directions to wrap a sphere - constitutes
+such a ratchet. By means of Lorentz transmission electron microscopy we show
+that micron-sized crystals of skyrmions in thin films of Cu2OSeO3 and MnSi
+display a unidirectional rotation motion. Our numerical simulations based on a
+stochastic Landau-Lifshitz-Gilbert equation suggest that this rotation is
+driven solely by thermal fluctuations in the presence of a temperature
+gradient, whereas in thermal equilibrium it is forbidden by the Bohr-van
+Leeuwen theorem. We show that the rotational flow of magnons driven by the
+effective magnetic field of skyrmions gives rise to the skyrmion rotation,
+therefore suggesting that magnons can be used to control the motion of these
+spin textures.",1504.05860v1
+2015-05-05,Evaluating the Potential of a Dual Randomized Kaczmarz Solver for Laplacian Linear Systems,"A new method for solving Laplacian linear systems proposed by Kelner et al.
+involves the random sampling and update of fundamental cycles in a graph.
+Kelner et al. proved asymptotic bounds on the complexity of this method but did
+not report experimental results. We seek to both evaluate the performance of
+this approach and to explore improvements to it in practice. We compare the
+performance of this method to other Laplacian solvers on a variety of real
+world graphs. We consider different ways to improve the performance of this
+method by exploring different ways of choosing the set of cycles and the
+sequence of updates, with the goal of providing more flexibility and potential
+parallelism. We propose a parallel model of the Kelner et al. method, for
+evaluating potential parallelism in terms of the span of edges updated at each
+iteration. We provide experimental results comparing the potential parallelism
+of the fundamental cycle basis and our extended cycle set. Our preliminary
+experiments show that choosing a non-fundamental set of cycles can save
+significant work compared to a fundamental cycle basis.",1505.00875v3
+2015-06-18,Area-Delay-Energy Tradeoffs of Strain-Mediated Multiferroic Devices,"Multiferroic devices hold profound promise for ultra-low energy computing in
+beyond Moore's law era. The magnetization of a magnetostrictive
+shape-anisotropic single-domain nanomagnet strain-coupled with a piezoelectric
+layer in a multiferroic composite structure can be switched between its two
+stable states (separated by an energy barrier) with a tiny amount of voltage
+via converse magnetoelectric effect. With appropriate choice of materials, the
+magnetization can be switched with a few tens of millivolts of voltages in
+sub-nanosecond switching delay while spending a miniscule amount of energy of
+~1 attojoule at room-temperature. Here, we analyze the area-delay-energy
+trade-offs of these multiferroic devices by solving stochastic
+Landau-Lifshitz-Gilbert equation in the presence of room-temperature thermal
+fluctuations. We particularly put attention on scaling down the lateral area of
+the magnetostrictive nanomagnet that can increase the device density on a chip.
+We show that the vertical thickness of the nanomagnet can be increased while
+scaling down the lateral area and keeping the assumption of single-domain limit
+valid. This has important consequence since it helps to some extent preventing
+the deterioration of the induced stress-anisotropy energy in the
+magnetostrictive nanomagnet, which is proportional to the nanomagnet's volume.
+The results show that if we scale down the lateral area, the switching delay
+increases while energy dissipation decreases. Avenues available to decrease the
+switching delay while still reducing the energy dissipation are discussed.",1506.07859v1
+2015-07-30,Confirmation of the Planetary Microlensing Signal and Star and Planet Mass Determinations for Event OGLE-2005-BLG-169,"We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3)
+observations of the source and lens stars for planetary microlensing event
+OGLE-2005-BLG-169, which confirm the relative proper motion prediction due to
+the planetary light curve signal observed for this event. This (and the
+companion Keck result) provide the first confirmation of a planetary
+microlensing signal, for which the deviation was only 2%. The follow-up
+observations determine the flux of the planetary host star in multiple
+passbands and remove light curve model ambiguity caused by sparse sampling of
+part of the light curve. This leads to a precise determination of the
+properties of the OGLE-2005-BLG-169Lb planetary system. Combining the
+constraints from the microlensing light curve with the photometry and
+astrometry of the HST/WFC3 data, we find star and planet masses of M_* = 0.69+-
+0.02 M_solar and m_p = 14.1 +- 0.9 M_earth. The planetary microlens system is
+located toward the Galactic bulge at a distance of D_L = 4.1 +- 0.4 kpc, and
+the projected star-planet separation is a_perp = 3.5 +- 0.3 AU, corresponding
+to a semi-major axis of a = 4.0 (+2.2 -0.6) AU.",1507.08661v1
+2015-08-19,Variations in solar wind fractionation as seen by ACE/SWICS over a solar cycle and the implications for Genesis Mission results,"We use ACE/SWICS elemental composition data to compare the variations in
+solar wind fractionation as measured by SWICS during the last solar maximum
+(1999-2001), the solar minimum (2006-2009) and the period in which the Genesis
+spacecraft was collecting solar wind (late 2001 - early 2004). We differentiate
+our analysis in terms of solar wind regimes (i.e. originating from interstream
+or coronal hole flows, or coronal mass ejecta). Abundances are normalized to
+the low-FIP ion magnesium to uncover correlations that are not apparent when
+normalizing to high-FIP ions. We find that relative to magnesium, the other
+low-FIP elements are measurably fractionated, but the degree of fractionation
+does not vary significantly over the solar cycle. For the high-FIP ions,
+variation in fractionation over the solar cycle is significant: greatest for
+Ne/Mg and C/Mg, less so for O/Mg, and the least for He/Mg. When abundance
+ratios are examined as a function of solar wind speed, we find a strong
+correlation, with the remarkable observation that the degree of fractionation
+follows a mass-dependent trend. We discuss the implications for correcting the
+Genesis sample return results to photospheric abundances.",1508.04566v1
+2015-08-28,Cosmic variance in the nanohertz gravitational wave background,"We use large N-body simulations and empirical scaling relations between dark
+matter halos, galaxies, and supermassive black holes to estimate the formation
+rates of supermassive black hole binaries and the resulting low-frequency
+stochastic gravitational wave background (GWB). We find this GWB to be
+relatively insensitive ($\lesssim10\%$) to cosmological parameters, with only
+slight variation between WMAP5 and Planck cosmologies. We find that uncertainty
+in the astrophysical scaling relations changes the amplitude of the GWB by a
+factor of $\sim 2$. Current observational limits are already constraining this
+predicted range of models. We investigate the Poisson variance in the amplitude
+of the GWB for randomly-generated populations of supermassive black holes,
+finding a scatter of order unity per frequency bin below 10 nHz, and increasing
+to a factor of $\sim 10$ near 100 nHz. This variance is a result of the rarity
+of the most massive binaries, which dominate the signal, and acts as a
+fundamental uncertainty on the amplitude of the underlying power law spectrum.
+This Poisson uncertainty dominates at $\gtrsim 20$ nHz, while at lower
+frequencies the dominant uncertainty is related to our poor understanding of
+the astrophysical scaling relations, although very low frequencies may be
+dominated by uncertainties related to the final parsec problem and the
+processes which drive binaries to the gravitational wave dominated regime.
+Cosmological effects are negligible at all frequencies.",1508.07336v2
+2015-09-01,Magnon-driven longitudinal spin Seebeck effect in F|N and N|F|N structures: role of asymmetric in-plane magnetic anisotropy,"The influence of an asymmetric in-plane magnetic anisotropy on the thermally
+activated spin current is studied theoretically for two different systems; (i)
+the system consisting of a ferromagnetic insulator in a direct contact with a
+nonmagnetic metal, and the sandwich structure consisting of a ferromagnetic
+insulating part sandwiched between two nonmagnetic metals. It is shown that
+when the difference between the temperatures of the two nonmagnetic metals in a
+structure is not large, the spin pumping currents from the magnetic part to the
+nonmagnetic ones are equal in amplitude and have opposite directions, so only
+the spin torque current contributes to the total spin current. The spin current
+flows then from the nonmagnetic metal with the higher temperature to the
+nonmagnetic metal having a lower temperature. Its amplitude varies linearly
+with the difference in temperatures. In addition, we have found that if the
+magnetic anisotropy is in the layer plane, then the spin current increases with
+the magnon temperature, while in the case of an out-of-plane magnetic
+anisotropy the spin current decreases when the magnon temperature enhances.
+Enlarging the difference between the temperatures of the nonmagnetic metals,
+the linear response becomes important, as confirmed by analytical expressions
+inferred from the Fokker-Planck approach and by the results obtained upon a
+full numerical integration of the stochastic Landau-Lifshitz-Gilbert equation.",1509.00376v1
+2015-09-08,Stellar Dynamics around a Massive Black Hole II: Resonant Relaxation,"We present a first-principles theory of Resonant Relaxation (RR) of a low
+mass stellar system orbiting a more massive black hole (MBH). We first extend
+the kinetic theory of Gilbert (1968) to include the Keplerian field of a black
+hole of mass $M_\bullet$. Specializing to a Keplerian stellar system of mass $M
+\ll M_\bullet$, we use the orbit-averaging method of Sridhar & Touma (2015;
+Paper I) to derive a kinetic equation for RR. This describes the collisional
+evolution of a system of $N \gg 1$ Gaussian Rings in a reduced 5-dim space,
+under the combined actions of self-gravity, 1 PN and 1.5 PN relativistic
+effects of the MBH and an arbitrary external potential. In general geometries
+RR is driven by both apsidal and nodal resonances, so the distinction between
+scalar-RR and vector-RR disappears. The system passes through a sequence of
+quasi-steady secular collisionless equilibria, driven by irreversible 2-Ring
+correlations that accrue through gravitational interactions, both direct and
+collective. This correlation function is related to a `wake function', which is
+the linear response of the system to the perturbation of a chosen Ring. The
+wake function is easier to appreciate, and satisfies a simpler equation, than
+the correlation function. We discuss general implications for the interplay of
+secular dynamics and non-equilibrium statistical mechanics in the evolution of
+Keplerian stellar systems toward secular thermodynamic equilibria, and set the
+stage for applications to the RR of axisymmetric discs in Paper III.",1509.02401v2
+2015-10-11,End-to-End Error-Correcting Codes on Networks with Worst-Case Symbol Errors,"The problem of coding for networks experiencing worst-case symbol errors is
+considered. We argue that this is a reasonable model for highly dynamic
+wireless network transmissions. We demonstrate that in this setup prior network
+error-correcting schemes can be arbitrarily far from achieving the optimal
+network throughput. A new transform metric for errors under the considered
+model is proposed. Using this metric, we replicate many of the classical
+results from coding theory. Specifically, we prove new Hamming-type,
+Plotkin-type, and Elias-Bassalygo-type upper bounds on the network capacity. A
+commensurate lower bound is shown based on Gilbert-Varshamov-type codes for
+error-correction. The GV codes used to attain the lower bound can be
+non-coherent, that is, they do not require prior knowledge of the network
+topology. We also propose a computationally-efficient concatenation scheme. The
+rate achieved by our concatenated codes is characterized by a Zyablov-type
+lower bound. We provide a generalized minimum-distance decoding algorithm which
+decodes up to half the minimum distance of the concatenated codes. The
+end-to-end nature of our design enables our codes to be overlaid on the
+classical distributed random linear network codes [1]. Furthermore, the
+potentially intensive computation at internal nodes for the link-by-link
+error-correction is un-necessary based on our design.",1510.03060v1
+2015-10-12,Analysis of laser shock experiments on precompressed samples using a quartz reference and application to warm dense hydrogen and helium,"Megabar (1 Mbar = 100 GPa) laser shocks on precompressed samples allow
+reaching unprecedented high densities and moderately high 10000-100000K
+temperatures. We describe here a complete analysis framework for the
+velocimetry (VISAR) and pyrometry (SOP) data produced in these experiments.
+Since the precompression increases the initial density of both the sample of
+interest and the quartz reference for pressure-density, reflectivity and
+temperature measurements, we describe analytical corrections based on available
+experimental data on warm dense silica and density-functional-theory based
+molecular dynamics computer simulations. Using our improved analysis framework
+we report a re-analysis of previously published data on warm dense hydrogen and
+helium, compare the newly inferred pressure, density and temperature data with
+most advanced equation of state models and provide updated reflectivity values.",1510.03301v1
+2015-11-09,Simulations of the Pairwise Kinematic Sunyaev-Zel'dovich Signal,"The pairwise kinematic Sunyaev-Zel'dovich (kSZ) signal from galaxy clusters
+is a probe of their line-of-sight momenta, and thus a potentially valuable
+source of cosmological information. In addition to the momenta, the amplitude
+of the measured signal depends on the properties of the intra-cluster gas and
+observational limitations such as errors in determining cluster centers and
+redshifts. In this work we simulate the pairwise kSZ signal of clusters at z<1,
+using the output from a cosmological N-body simulation and including the
+properties of the intra-cluster gas via a model that can be varied in
+post-processing. We find that modifications to the gas profile due to star
+formation and feedback reduce the pairwise kSZ amplitude of clusters by ~50%,
+relative to the naive 'gas traces mass' assumption. We demonstrate that
+mis-centering can reduce the overall amplitude of the pairwise kSZ signal by up
+to 10%, while redshift errors can lead to an almost complete suppression of the
+signal at small separations. We confirm that a high-significance detection is
+expected from the combination of data from current-generation, high-resolution
+CMB experiments, such as the South Pole Telescope, and cluster samples from
+optical photometric surveys, such as the Dark Energy Survey. Furthermore, we
+forecast that future experiments such as Advanced ACTPol in conjunction with
+data from the Dark Energy Spectroscopic Instrument will yield detection
+significances of at least 20{\sigma}, and up to 57{\sigma} in an optimistic
+scenario. Our simulated maps are publicly available at:
+http://www.hep.anl.gov/cosmology/ksz.html",1511.02843v2
+2015-11-11,Magnetization switching by current and microwaves,"We propose a theoretical model of magnetization switching in a ferromagnetic
+multilayer by both electric current and microwaves. The electric current gives
+a spin transfer torque on the magnetization, while the microwaves induce a
+precession of the magnetization around the initial state. Based on numerical
+simulation of the Landau-Lifshitz-Gilbert (LLG) equation, it is found that the
+switching current is significantly reduced compared with the switching caused
+solely by the spin transfer torque when the microwave frequency is in a certain
+range. We develop a theory of switching from the LLG equation averaged over a
+constant energy curve. It was found that the switching current should be
+classified into four regions, depending on the values of the microwave
+frequency. Based on the analysis, we derive an analytical formula of the
+optimized frequency minimizing the switching current, which is smaller than the
+ferromagnetic resonance frequency. We also derive an analytical formula of the
+minimized switching current. Both the optimized frequency and the minimized
+switching current decrease with increasing the amplitude of the microwave
+field. The results will be useful to achieve high thermal stability and low
+switching current in spin torque systems simultaneously.",1511.03366v2
+2015-11-13,"Time-domain numerical modeling of brass instruments including nonlinear wave propagation, viscothermal losses, and lips vibration","A time-domain numerical modeling of brass instruments is proposed. On one
+hand, outgoing and incoming waves in the resonator are described by the
+Menguy-Gilbert model, which incorporates three key issues: nonlinear wave
+propagation, viscothermal losses, and a variable section. The non-linear
+propagation is simulated by a TVD scheme well-suited to non-smooth waves. The
+fractional derivatives induced by the viscothermal losses are replaced by a set
+of local-in-time memory variables. A splitting strategy is followed to couple
+optimally these dedicated methods. On the other hand, the exciter is described
+by a one-mass model for the lips. The Newmark method is used to integrate the
+nonlinear ordinary differential equation so-obtained. At each time step, a
+coupling is performed between the pressure in the tube and the displacement of
+the lips. Finally, an extensive set of validation tests is successfully
+completed. In particular, self-sustained oscillations of the lips are simulated
+by taking into account the nonlinear wave propagation in the tube. Simulations
+clearly indicate that the nonlinear wave propagation has a major influence on
+the timbre of the sound, as expected. Moreover, simulations also highlight an
+influence on playing frequencies, time envelopes and on the playability of the
+low frequencies in the case of a variable lips tension.",1511.04247v1
+2015-11-24,Planetary Candidates from the First Year of the K2 Mission,"The Kepler Space Telescope is currently searching for planets transiting
+stars along the ecliptic plane as part of its extended K2 mission. We processed
+the publicly released data from the first year of K2 observations (Campaigns 0,
+1, 2, and 3) and searched for periodic eclipse signals consistent with
+planetary transits. Out of 59,174 targets we searched, we detect 234 planetary
+candidates around 208 stars. These candidates range in size from gas giants to
+smaller than the Earth, and range in orbital periods from hours to over a
+month. We conducted initial reconnaissance spectroscopy of 68 of the brighter
+candidate host stars, and present high resolution optical spectra for these
+stars. We make all of our data products, including light curves, spectra, and
+vetting diagnostics available to users online.",1511.07820v2
+2015-11-25,A Search for Water in the Atmosphere of HAT-P-26b Using LDSS-3C,"The characterization of a physically-diverse set of transiting exoplanets is
+an important and necessary step towards establishing the physical properties
+linked to the production of obscuring clouds or hazes. It is those planets with
+identifiable spectroscopic features that can most effectively enhance our
+understanding of atmospheric chemistry and metallicity. The newly-commissioned
+LDSS-3C instrument on Magellan provides enhanced sensitivity and suppressed
+fringing in the red optical, thus advancing the search for the spectroscopic
+signature of water in exoplanetary atmospheres from the ground. Using data
+acquired by LDSS-3C and the Spitzer Space Telescope, we search for evidence of
+water vapor in the transmission spectrum of the Neptune-mass planet HAT-P-26b.
+Our measured spectrum is best explained by the presence of water vapor, a lack
+of potassium, and either a high-metallicity, cloud-free atmosphere or a
+solar-metallicity atmosphere with a cloud deck at ~10 mbar. The emergence of
+multi-scale-height spectral features in our data suggests that future
+observations at higher precision could break this degeneracy and reveal the
+planet's atmospheric chemical abundances. We also update HAT-P-26b's transit
+ephemeris, t_0 = 2455304.65218(25) BJD_TDB, and orbital period, p =
+4.2345023(7) days.",1511.08226v2
+2015-12-22,Induced voltage in an open wire,"A puzzle arising from Faraday's law is considered and solved concerning the
+question which voltage is induced in an open wire with a time-varying
+homogeneous magnetic field. In contrast to closed wires where the voltage is
+determined by the time variance of magnetic field and enclosed area, in an open
+wire we have to integrate the electric field along the wire. It is found that
+the longitudinal electric field contributes with 1/3 and the transverse field
+with 2/3 to the induced voltage. In order to find the electric fields the
+sources of the magnetic fields are necessary to know. The representation of a
+homogeneous and time-varying magnetic field implies unavoidably a certain
+symmetry point or symmetry line which depend on the geometry of the source. As
+a consequence the induced voltage of an open wire is found to be the area
+covered with respect to this symmetry line or point perpendicular to the
+magnetic field. This in turn allows to find the symmetry points of a magnetic
+field source by measuring the voltage of an open wire placed with different
+angles in the magnetic field. We present exactly solvable models for a symmetry
+point and for a symmetry line, respectively. The results are applicable to open
+circuit problems like corrosion and for astrophysical applications.",1512.07133v3
+2015-12-22,Charge transport and vector meson dissociation across the thermal phase transition in lattice QCD with two light quark flavors,"We compute and analyze correlation functions in the isovector vector channel
+at vanishing spatial momentum across the deconfinement phase transition in
+lattice QCD. The simulations are carried out at temperatures $T/T_c=0.156, 0.8,
+1.0, 1.25$ and $1.67$ with $T_c\simeq203$MeV for two flavors of Wilson-Clover
+fermions with a zero-temperature pion mass of $\simeq270$MeV. Exploiting exact
+sum rules and applying a phenomenologically motivated ansatz allows us to
+determine the spectral function $\rho(\omega,T)$ via a fit to the lattice
+correlation function data. From these results we estimate the electrical
+conductivity across the deconfinement phase transition via a Kubo formula and
+find evidence for the dissociation of the $\rho$ meson by resolving its
+spectral weight at the available temperatures. We also apply the Backus-Gilbert
+method as a model-independent approach to this problem. At any given frequency,
+it yields a local weighted average of the true spectral function. We use this
+method to compare kinetic theory predictions and previously published
+phenomenological spectral functions to our lattice study.",1512.07249v1
+2016-01-18,Search for transiting exoplanets and variable stars in the open cluster NGC 7243,"We report results of the first five observing campaigns for the open stellar
+cluster NGC 7243 in the frame of project Young Exoplanet Transit Initiative
+(YETI). The project focuses on the monitoring of young and nearby stellar
+clusters, with the aim to detect young transiting exoplanets, and to study
+other variability phenomena on time-scales from minutes to years. After five
+observing campaigns and additional observations during 2013 and 2014, a clear
+and repeating transit-like signal was detected in the light curve of
+J221550.6+495611. Furthermore, we detected and analysed 37 new eclipsing binary
+stars in the studied region. The best fit parameters and light curves of all
+systems are given. Finally, we detected and analysed 26 new, presumably
+pulsating variable stars in the studied region. The follow-up investigation of
+these objects, including spectroscopic measurements of the exoplanet candidate,
+is currently planned.",1601.04562v1
+2016-01-21,Basker: A Threaded Sparse LU Factorization Utilizing Hierarchical Parallelism and Data Layouts,"Scalable sparse LU factorization is critical for efficient numerical
+simulation of circuits and electrical power grids. In this work, we present a
+new scalable sparse direct solver called Basker. Basker introduces a new
+algorithm to parallelize the Gilbert-Peierls algorithm for sparse LU
+factorization. As architectures evolve, there exists a need for algorithms that
+are hierarchical in nature to match the hierarchy in thread teams, individual
+threads, and vector level parallelism. Basker is designed to map well to this
+hierarchy in architectures. There is also a need for data layouts to match
+multiple levels of hierarchy in memory. Basker uses a two-dimensional
+hierarchical structure of sparse matrices that maps to the hierarchy in the
+memory architectures and to the hierarchy in parallelism. We present
+performance evaluations of Basker on the Intel SandyBridge and Xeon Phi
+platforms using circuit and power grid matrices taken from the University of
+Florida sparse matrix collection and from Xyce circuit simulations. Basker
+achieves a geometric mean speedup of 5.91x on CPU (16 cores) and 7.4x on Xeon
+Phi (32 cores) relative to KLU. Basker outperforms Intel MKL Pardiso (PMKL) by
+as much as 53x on CPU (16 cores) and 13.3x on Xeon Phi (32 cores) for low
+fill-in circuit matrices. Furthermore, Basker provides 5.4x speedup on a
+challenging matrix sequence taken from an actual Xyce simulation.",1601.05725v1
+2016-02-16,JSJ decompositions of groups,"This is an account of the theory of JSJ decompositions of finitely generated
+groups, as developed in the last twenty years or so.
+  We give a simple general definition of JSJ decompositions (or rather of their
+Bass-Serre trees), as maximal universally elliptic trees. In general, there is
+no preferred JSJ decomposition, and the right object to consider is the whole
+set of JSJ decompositions, which forms a contractible space: the JSJ
+deformation space (analogous to Outer Space).
+  We prove that JSJ decompositions exist for any finitely presented group,
+without any assumption on edge groups. When edge groups are slender, we
+describe flexible vertices of JSJ decompositions as quadratically hanging
+extensions of 2-orbifold groups.
+  Similar results hold in the presence of acylindricity, in particular for
+splittings of torsion-free CSA groups over abelian groups, and splittings of
+relatively hyperbolic groups over virtually cyclic or parabolic subgroups.
+Using trees of cylinders, we obtain canonical JSJ trees (which are invariant
+under automorphisms).
+  We introduce a variant in which the property of being universally elliptic is
+replaced by the more restrictive and rigid property of being universally
+compatible. This yields a canonical compatibility JSJ tree, not just a
+deformation space. We show that it exists for any finitely presented group.
+  We give many examples, and we work throughout with relative decompositions
+(restricting to trees where certain subgroups are elliptic).",1602.05139v2
+2016-03-28,Write error rate of spin-transfer-torque random access memory including micromagnetic effects using rare event enhancement,"Spin-transfer-torque random access memory (STT-RAM) is a promising candidate
+for the next-generation of random-access-memory due to improved scalability,
+read-write speeds and endurance. However, the write pulse duration must be long
+enough to ensure a low write error rate (WER), the probability that a bit will
+remain unswitched after the write pulse is turned off, in the presence of
+stochastic thermal effects. WERs on the scale of 10$^{-9}$ or lower are
+desired. Within a macrospin approximation, WERs can be calculated analytically
+using the Fokker-Planck method to this point and beyond. However, dynamic
+micromagnetic effects within the bit can affect and lead to faster switching.
+Such micromagnetic effects can be addressed via numerical solution of the
+stochastic Landau-Lifshitz-Gilbert-Slonczewski (LLGS) equation. However,
+determining WERs approaching 10$^{-9}$ would require well over 10$^{9}$ such
+independent simulations, which is infeasible. In this work, we explore
+calculation of WER using ""rare event enhancement"" (REE), an approach that has
+been used for Monte Carlo simulation of other systems where rare events
+nevertheless remain important. Using a prototype REE approach tailored to the
+STT-RAM switching physics, we demonstrate reliable calculation of a WER to
+10$^{-9}$ with sets of only approximately 10$^{3}$ ongoing stochastic LLGS
+simulations, and the apparent ability to go further.",1603.08512v2
+2016-04-04,Probing unconventional superconductivity in inversion symmetric doped Weyl semimetal,"Unconventional superconductivity has been predicted to arise in the
+topologically non-trivial Fermi surface of doped inversion symmetric Weyl
+semimetals (WSM). In particular, Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) and
+nodal BCS states are theoretically predicted to be possible superconductor
+pairing states in inversion symmetric doped WSM. In an effort to resolve
+preferred pairing state, we theoretically study two separate four terminal
+quantum transport methods that each exhibit a unique electrical signature in
+the presence of FFLO and nodal BCS states in doped WSMs. We first introduce a
+Josephson junction that consists of a doped WSM and an s-wave superconductor in
+which we show that the application of a transverse uniform current in s-wave
+superconductor effectively cancels the momentum carried by FFLO states in doped
+WSM. From our numerical analysis, we find a peak in Josephson current amplitude
+at finite uniform current in s-wave superconductor that serves as an indicator
+of FFLO states in doped WSMs. Furthermore, we show using a four terminal
+measurement configuration that the nodal points may be shifted by an
+application of transverse uniform current in doped WSM. We analyze the
+topological phase transitions induced by nodal pair annihilation in
+non-equilibrium by constructing the phase diagram and we find a characteristic
+decrease in the density of states that serves as a signature of the quantum
+critical point in the topological phase transition, thereby identifying nodal
+BCS states in doped WSM.",1604.01040v1
+2016-04-22,Opt: A Domain Specific Language for Non-linear Least Squares Optimization in Graphics and Imaging,"Many graphics and vision problems can be expressed as non-linear least
+squares optimizations of objective functions over visual data, such as images
+and meshes. The mathematical descriptions of these functions are extremely
+concise, but their implementation in real code is tedious, especially when
+optimized for real-time performance on modern GPUs in interactive applications.
+In this work, we propose a new language, Opt (available under
+http://optlang.org), for writing these objective functions over image- or
+graph-structured unknowns concisely and at a high level. Our compiler
+automatically transforms these specifications into state-of-the-art GPU solvers
+based on Gauss-Newton or Levenberg-Marquardt methods. Opt can generate
+different variations of the solver, so users can easily explore tradeoffs in
+numerical precision, matrix-free methods, and solver approaches. In our
+results, we implement a variety of real-world graphics and vision applications.
+Their energy functions are expressible in tens of lines of code, and produce
+highly-optimized GPU solver implementations. These solver have performance
+competitive with the best published hand-tuned, application-specific GPU
+solvers, and orders of magnitude beyond a general-purpose auto-generated
+solver.",1604.06525v3
+2016-05-06,Spin orbit alignment for KELT-7b and HAT-P-56b via Doppler tomography with TRES,"We present Doppler tomographic analyses for the spectroscopic transits of
+KELT-7b and HAT-P-56b, two hot-Jupiters orbiting rapidly rotating F-dwarf host
+stars. These include analyses of archival TRES observations for KELT-7b, and a
+new TRES transit observation of HAT-P-56b. We report spin-orbit aligned
+geometries for KELT-7b (2.7 +/- 0.6 deg) and HAT-P-56b (8 +/- 2 deg). The host
+stars KELT-7 and HAT-P-56 are among some of the most rapidly rotating
+planet-hosting stars known. We examine the tidal re-alignment model for the
+evolution of the spin-orbit angle in the context of the spin rates of these
+stars. We find no evidence that the rotation rates of KELT-7 and HAT-P-56 have
+been modified by star-planet tidal interactions, suggesting that the spin-orbit
+angle of systems around these hot stars may represent their primordial
+configuration. In fact, KELT-7 and HAT-P-56 are two of three systems in
+super-synchronous, spin-orbit aligned states, where the rotation periods of the
+host stars are faster than the orbital periods of the planets.",1605.01991v1
+2016-06-18,Mathematical Foundations of the GraphBLAS,"The GraphBLAS standard (GraphBlas.org) is being developed to bring the
+potential of matrix based graph algorithms to the broadest possible audience.
+Mathematically the Graph- BLAS defines a core set of matrix-based graph
+operations that can be used to implement a wide class of graph algorithms in a
+wide range of programming environments. This paper provides an introduction to
+the mathematics of the GraphBLAS. Graphs represent connections between vertices
+with edges. Matrices can represent a wide range of graphs using adjacency
+matrices or incidence matrices. Adjacency matrices are often easier to analyze
+while incidence matrices are often better for representing data. Fortunately,
+the two are easily connected by matrix mul- tiplication. A key feature of
+matrix mathematics is that a very small number of matrix operations can be used
+to manipulate a very wide range of graphs. This composability of small number
+of operations is the foundation of the GraphBLAS. A standard such as the
+GraphBLAS can only be effective if it has low performance overhead. Performance
+measurements of prototype GraphBLAS implementations indicate that the overhead
+is low.",1606.05790v2
+2016-07-15,Influence of grain size and exchange interaction on the LLB modeling procedure,"Reliably predicting bit-error rates in realistic heat-assisted magnetic
+recording simulations is a challenging task. Integrating the
+Landau-Lifshitz-Bloch (LLB) equation can reduce the computational effort to
+determine the magnetization dynamics in the vicinity of the Curie temperature.
+If one aims that these dynamics coincide with trajectories calculated from the
+atomistic Landau-Lifshitz-Gilbert equation, one has to carefully model required
+temperature dependent material functions such as the zero-field equilibrium
+magnetization as well as the parallel and normal susceptibilities. We present
+an extensive study on how these functions depend on grain size and exchange
+interactions. We show that, if the size or the exchange constant of a reference
+grain is modified, the material functions can be scaled, according to the
+changed Curie temperature, yielding negligible errors. This is shown to be
+valid for volume changes of up to $\pm 40$ % and variations of the exchange
+constant of up to $\pm10$ %. Besides the temperature dependent material curves,
+computed switching probabilities also agree well with probabilities separately
+determined for each system. Our study suggest that there is no need to
+recalculate the required LLB input functions for each particle. Within the
+presented limits it is sufficient to scale them to the Curie temperature of the
+altered system.",1607.04480v1
+2016-08-23,Thermal stability and irreversibility of skyrmion-lattice phases in Cu$_2$OSeO$_3$,"Small angle neutron scattering measurements have been performed to study the
+thermodynamic stability of skyrmion-lattice phases in Cu$_2$OSeO$_3$. We found
+that the two distinct skyrmion-lattice phases [SkX(1) and SkX(2) phases] can be
+stabilized through different thermal histories; by cooling from the
+paramagnetic phase under finite magnetic field, the SkX(2) phase is selected.
+On the other hand, the 30$^{\circ}$-rotated SkX(1) phase becomes dominant by
+heating the sample from the ordered conical phase under finite field. This
+difference in stabilization is surprisingly similar to the irreversibility
+observed in spin glasses. The zero-field cooling results in the co-existence of
+the two phases. It is further found that once one of the skyrmion-lattice
+phases is formed, it is hardly destabilized. This indicates unusual thermal
+stability of the two skyrmion-lattice phases originating from an unexpectedly
+large energy barrier between them.",1608.06359v2
+2016-08-24,Carbon Stars in the Satellites and Halo of M31,"We spectroscopically identify a sample of carbon stars in the satellites and
+halo of M31 using moderate-resolution optical spectroscopy from the
+Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo survey. We
+present the photometric properties of our sample of 41 stars, including their
+brightness with respect to the tip of the red giant branch (TRGB) and their
+distributions in various color-color spaces. This analysis reveals a bluer
+population of carbon stars fainter than the TRGB and a redder population of
+carbon stars brighter than the TRGB. We then apply principal component analysis
+to determine the sample's eigenspectra and eigencoefficients. Correlating the
+eigencoefficients with various observable properties reveals the spectral
+features that trace effective temperature and metallicity. Putting the
+spectroscopic and photometric information together, we find the carbon stars in
+the satellites and halo of M31 to be minimally impacted by dust and internal
+dynamics. We also find that while there is evidence to suggest that the
+sub-TRGB stars are extrinsic in origin, it is also possible that they are are
+particularly faint members of the asymptotic giant branch.",1608.06714v1
+2016-09-12,"Discovery and Precise Characterization by the MEarth Project of LP 661-13, an Eclipsing Binary Consisting of Two Fully Convective Low-mass Stars","We report the detection of stellar eclipses in the LP 661-13 system. We
+present the discovery and characterization of this system, including high
+resolution spectroscopic radial velocities and a photometric solution spanning
+two observing seasons. LP 661-13 is a low mass binary system with an orbital
+period of $4.7043512^{+0.0000013}_{-0.0000010}$ days at a distance of $24.9 \pm
+1.3$ parsecs. LP 661-13A is a $0.30795 \pm 0.00084$ $M_\odot$ star while LP
+661-13B is a $0.19400 \pm 0.00034$ $M_\odot$ star. The radius of each component
+is $0.3226 \pm 0.0033$ $R_\odot$ and $0.2174 \pm 0.0023$ $R_\odot$,
+respectively. We detect out of eclipse modulations at a period slightly shorter
+than the orbital period, implying that at least one of the components is not
+rotating synchronously. We find that each component is slightly inflated
+compared to stellar models, and that this cannot be reconciled through age or
+metallicity effects. As a nearby eclipsing binary system where both components
+are near or below the full-convection limit, LP 661-13 will be a valuable test
+of models for the structure of cool dwarf stars.",1609.03591v1
+2016-09-14,"Topological superconductivity in an ultrathin, magnetically-doped topological insulator proximity coupled to a conventional superconductor","As a promising candidate system to realize topological superconductivity, the
+system of a 3D topological insulator (TI) grown on top of the s-wave
+superconductor has been extensively studied. To access the topological
+superconductivity experimentally, the 3D TI sample must be thin enough to allow
+for Cooper pair tunneling to the exposed surface of TI. The use of magnetically
+ordered dopants to break time-reversal symmetry may allow the surface of a TI
+to host Majorana fermion, which are believed to be a signature of topological
+superconductivity. In this work, we study a magnetically-doped thin film
+TI-superconductor hybrid systems. Considering the proximity induced order
+parameter in thin film of TI, we analyze the gap closing points of the
+Hamiltonian and draw the phase diagram as a function of relevant parameters:
+the hybridization gap, Zeeman energy, and chemical potential of the TI system.
+Our findings provide a useful guide in choosing relevant parameters to
+facilitate the observation of topological superconductivity in thin film
+TI-superconductor hybrid systems. In addition, we further perform numerical
+analysis on a TI proximity coupled to a s-wave superconductor and find that,
+due to the spin-momentum locked nature of the surface states in TI, the induced
+s-wave order parameter of the surface states persists even at large magnitude
+of the Zeeman energy.",1609.04129v2
+2016-09-16,Convex separation from convex optimization for large-scale problems,"We present a scheme, based on Gilbert's algorithm for quadratic minimization
+[SIAM J. Contrl., vol. 4, pp. 61-80, 1966], to prove separation between a point
+and an arbitrary convex set $S\subset\mathbb{R}^{n}$ via calls to an oracle
+able to perform linear optimizations over $S$. Compared to other methods, our
+scheme has almost negligible memory requirements and the number of calls to the
+optimization oracle does not depend on the dimensionality $n$ of the underlying
+space. We study the speed of convergence of the scheme under different promises
+on the shape of the set $S$ and/or the location of the point, validating the
+accuracy of our theoretical bounds with numerical examples. Finally, we present
+some applications of the scheme in quantum information theory. There we find
+that our algorithm out-performs existing linear programming methods for certain
+large scale problems, allowing us to certify nonlocality in bipartite scenarios
+with upto $42$ measurement settings. We apply the algorithm to upper bound the
+visibility of two-qubit Werner states, hence improving known lower bounds on
+Grothendieck's constant $K_G(3)$. Similarly, we compute new upper bounds on the
+visibility of GHZ states and on the steerability limit of Werner states for a
+fixed number of measurement settings.",1609.05011v2
+2016-09-18,Narrowly distributed crystal orientation in biomineral vaterite,"Biominerals formed by animals provide skeletal support, and many other
+functions. They were previously shown to grow by aggregation of amorphous
+nanoparticles, but never to grow ion-by-ion from solution, which is a common
+growth mechanism for abiotic crystals. We analyze vaterite CaCO3 multi
+crystalline spicules from the solitary tunicate Herdmania momus, with
+Polarization dependent Imaging Contrast PIC mapping, scanning and aberration
+corrected transmission electron microscopies. The first fully quantitative PIC
+mapping data, presented here, measured 0{\deg} 30{\deg} angle spreads between
+immediately adjacent crystals. Such narrowly distributed crystal orientations
+demonstrate that crystallinity does not propagate from one crystal to another
+0{\deg} angle spreads, nor that new crystals with random orientation 90{\deg}
+nucleate. There are no organic layers at the interface between crystals, hence
+a new, unknown growth mechanism must be invoked, with crystal nucleation
+constrained within 30{\deg}. Two observations are consistent with crystal
+growth from solution: vaterite microcrystals express crystal faces, and are
+smooth at the nanoscale after cryo fracture. The observation of 30{\deg} angle
+spreads, lack of interfacial organic layers, and smooth fracture figures
+broadens the range of known biomineralization mechanisms and may inspire novel
+synthetic crystal growth strategies. Spherulitic growth from solution is one
+possible mechanism consistent with all these observations.",1609.05449v1
+2016-09-29,Multiscale Model Approach for Magnetization Dynamics Simulations,"Simulations of magnetization dynamics in a multiscale environment enable
+rapid evaluation of the Landau-Lifshitz-Gilbert equation in a mesoscopic sample
+with nanoscopic accuracy in areas where such accuracy is required. We have
+developed a multiscale magnetization dynamics simulation approach that can be
+applied to large systems with spin structures that vary locally on small length
+scales. To implement this, the conventional micromagnetic simulation framework
+has been expanded to include a multiscale solving routine. The software
+selectively simulates different regions of a ferromagnetic sample according to
+the spin structures located within in order to employ a suitable discretization
+and use either a micromagnetic or an atomistic model. To demonstrate the
+validity of the multiscale approach, we simulate the spin wave transmission
+across the regions simulated with the two different models and different
+discretizations. We find that the interface between the regions is fully
+transparent for spin waves with frequency lower than a certain threshold set by
+the coarse scale micromagnetic model with no noticeable attenuation due to the
+interface between the models. As a comparison to exact analytical theory, we
+show that in a system with Dzyaloshinskii-Moriya interaction leading to spin
+spiral, the simulated multiscale result is in good quantitative agreement with
+the analytical calculation.",1609.09295v1
+2016-12-21,Geometric generalised Lagrangian mean theories,"Many fluctuation-driven phenomena in fluids can be analysed effectively using
+the generalised Lagrangian mean (GLM) theory of Andrews & McIntyre (1978). This
+theory relies on particle-following averaging to incorporate the constraints
+imposed by the material conservations. It relies implicitly on an Euclidean
+structure; as a result, it does not have a geometrically intrinsic
+interpretation and suffers from undesirable features, including the divergence
+of the Lagrangian-mean velocity for incompressible fluids. Motivated by this,
+we develop a geometric generalisation of GLM that we formulate intrinsically.
+The theory applies to arbitrary Riemannian manifolds; it also establishes a
+clear distinction between results that stem directly from geometric consistency
+and those that depend on particular choices. We show that the Lagrangian mean
+momentum -- the average of the pull-back of the momentum one-form -- obeys a
+simple equation which guarantees the conservation of Kelvin's circulation,
+irrespective of the mean-flow definition. We discuss four possible definitions
+of the mean flow: a direct extension of standard GLM, a definition based on
+optimal transportation, a definition based on a geodesic distance in the group
+of volume-preserving diffeomorphisms, and the glm definition proposed by Soward
+& Roberts (2010). Assuming small-amplitude perturbations, we carry out
+order-by-order calculations to obtain explicit expressions for the mean flow
+and pseudomomentum at leading order. We also show how the wave-action
+conservation of GLM extends to the geometric setting. To make the paper
+self-contained, we introduce the tools of differential geometry and main ideas
+of geometric fluid dynamics on which we rely. We mostly focus on the Euler
+equations for incompressible inviscid fluids but sketch out extensions to the
+rotating-stratified Boussinesq, compressible Euler and magnetohydrodynamic
+equations.",1612.07111v3
+2017-01-13,A Multi-Planet System Transiting the $V$ = 9 Rapidly Rotating F-Star HD 106315,"We report the discovery of a multi-planet system orbiting HD 106315, a
+rapidly rotating mid F-type star, using data from the K2 mission. HD 106315
+hosts a $2.51\pm0.12\,R_\oplus$ sub-Neptune in a 9.5 day orbit, and a
+$4.31_{-0.27}^{+0.24}\,R_\oplus$ super-Neptune in a 21 day orbit. The projected
+rotational velocity of HD 106315 (12.9 km s$^{-1}$) likely precludes precise
+measurements of the planets' masses, but could enable a measurement of the
+sky-projected spin-orbit obliquity for the outer planet via Doppler tomography.
+The eccentricities of both planets were constrained to be consistent with 0,
+following a global modeling of the system that includes a Gaia distance and
+dynamical arguments. The HD 106315 system is one of few multi-planet systems
+hosting a Neptune-sized planet for which orbital obliquity measurements are
+possible, making it an excellent test-case for formation mechanisms of
+warm-Neptunian systems. The brightness of the host star also makes HD 106315 c
+a candidate for future transmission spectroscopic follow-up studies.",1701.03807v2
+2017-01-17,"The Landau-Lifshitz equation, the NLS, and the magnetic rogue wave as a by-product of two colliding regular ""positons""","In this article we present a new method for construction of exact solutions
+of the Landau-Lifshitz-Gilbert equation (LLG) for ferromagnetic nanowires. The
+method is based on the established relationship between the LLG and the
+nonlinear Schr\""odinger equation (NLS), and is aimed at resolving an old
+problem: how to produce multiple-rogue wave solutions of NLS using just the
+Darboux-type transformations. The solutions of this type - known as P-breathers
+- have been proven to exist by Dubard and Matveev, but their technique heavily
+relied on using the solutions of yet another nonlinear equation,
+Kadomtsev-Petviashvili I equation (KP-I), and its relationship with NLS. We
+have shown that in fact one doesn't have to use KP-I but can instead reach the
+same results just with NLS solutions, but only if they are dressed via the
+binary Darboux transformation. In particular, our approach allows to construct
+all the Dubard-Matveev P-breathers. Furthermore, the new method can lead to
+some completely new, previously unknown solutions. One particular solution that
+we have constructed describes two positon-like waves, colliding with each other
+and in the process producing a new, short-lived rogue wave. We called this
+unusual solution (rogue wave begotten after the impact of two solitons) the
+""impacton"".",1701.04903v3
+2017-01-24,Partial Bridging of Vaccine Efficacy to New Populations,"Suppose one has data from one or more completed vaccine efficacy trials and
+wishes to estimate the efficacy in a new setting. Often logistical or ethical
+considerations make running another efficacy trial impossible. Fortunately, if
+there is a biomarker that is the primary modifier of efficacy, then the
+biomarker-conditional efficacy may be identical in the completed trials and the
+new setting, or at least informative enough to meaningfully bound this
+quantity. Given a sample of this biomarker from the new population, we might
+hope we can bridge the results of the completed trials to estimate the vaccine
+efficacy in this new population. Unfortunately, even knowing the true
+conditional efficacy in the new population fails to identify the marginal
+efficacy due to the unknown conditional unvaccinated risk. We define a curve
+that partially identifies (lower bounds) the marginal efficacy in the new
+population as a function of the population's marginal unvaccinated risk, under
+the assumption that one can identify bounds on the conditional unvaccinated
+risk in the new population. Interpreting the curve only requires identifying
+plausible regions of the marginal unvaccinated risk in the new population. We
+present a nonparametric estimator of this curve and develop valid lower
+confidence bounds that concentrate at a parametric rate. We use vaccine
+terminology throughout, but the results apply to general binary interventions
+and bounded outcomes.",1701.06739v1
+2017-02-07,Resonant spin transfer torque nano-oscillators,"Spin transfer torque nano-oscillators are potential candidates for replacing
+the traditional inductor based voltage controlled oscillators in modern
+communication devices. Typical oscillator designs are based on trilayer
+magnetic tunnel junctions which are disadvantaged by low power outputs and poor
+conversion efficiencies. In this letter, we theoretically propose to use
+resonant spin filtering in pentalayer magnetic tunnel junctions as a possible
+route to alleviate these issues and present device designs geared toward a high
+microwave output power and an efficient conversion of the d.c. input power. We
+attribute these robust qualities to the resulting non-trivial spin current
+profiles and the ultra high tunnel magnetoresistance, both arising from
+resonant spin filtering. The device designs are based on the nonequilibrium
+Green's function spin transport formalism self-consistently coupled with the
+stochastic Landau-Lifshitz-Gilbert-Slonczewski's equation and the Poisson's
+equation. We demonstrate that the proposed structures facilitate oscillator
+designs featuring a large enhancement in microwave power of around $775\%$ and
+an efficiency enhancement of over $1300\%$ in comparison with typical trilayer
+designs. We also rationalize the optimum operating regions via an analysis of
+the dynamic and static device resistances. This work sets stage for pentalyer
+spin transfer torque nano-oscillator device designs that extenuate most of the
+issues faced by the typical trilayer designs.",1702.01869v1
+2017-03-17,Communication Primitives in Cognitive Radio Networks,"Cognitive radio networks are a new type of multi-channel wireless network in
+which different nodes can have access to different sets of channels. By
+providing multiple channels, they improve the efficiency and reliability of
+wireless communication. However, the heterogeneous nature of cognitive radio
+networks also brings new challenges to the design and analysis of distributed
+algorithms.
+  In this paper, we focus on two fundamental problems in cognitive radio
+networks: neighbor discovery, and global broadcast. We consider a network
+containing $n$ nodes, each of which has access to $c$ channels. We assume the
+network has diameter $D$, and each pair of neighbors have at least $k\geq 1$,
+and at most $k_{max}\leq c$, shared channels. We also assume each node has at
+most $\Delta$ neighbors. For the neighbor discovery problem, we design a
+randomized algorithm CSeek which has time complexity
+$\tilde{O}((c^2/k)+(k_{max}/k)\cdot\Delta)$. CSeek is flexible and robust,
+which allows us to use it as a generic ""filter"" to find ""well-connected""
+neighbors with an even shorter running time. We then move on to the global
+broadcast problem, and propose CGCast, a randomized algorithm which takes
+$\tilde{O}((c^2/k)+(k_{max}/k)\cdot\Delta+D\cdot\Delta)$ time. CGCast uses
+CSeek to achieve communication among neighbors, and uses edge coloring to
+establish an efficient schedule for fast message dissemination.
+  Towards the end of the paper, we give lower bounds for solving the two
+problems. These lower bounds demonstrate that in many situations, CSeek and
+CGCast are near optimal.",1703.06130v1
+2017-03-22,Magnetization induced dynamics of a Josephson junction coupled to a nanomagnet,"We study the superconducting current of a Josephson junction (JJ) coupled to
+an external nanomagnet driven by a time dependent magnetic field both without
+and in the presence of an external AC drive. We provide an analytic, albeit
+perturbative, solution for the Landau-Lifshitz (LL) equations governing the
+coupled JJ-nanomagnet system in the presence of a magnetic field with arbitrary
+time-dependence oriented along the easy axis of the nanomagnet's magnetization
+and in the limit of weak dimensionless coupling $\epsilon_0$ between the JJ and
+the nanomagnet. We show the existence of Shapiro-like steps in the I-V
+characteristics of the JJ subjected to a voltage bias for a constant or
+periodically varying magnetic field and explore the effect of rotation of the
+magnetic field and the presence of an external AC drive on these steps. We
+support our analytic results with exact numerical solution of the LL equations.
+We also extend our results to dissipative nanomagnets by providing a
+perturbative solution to the Landau-Lifshitz-Gilbert (LLG) equations for weak
+dissipation. We study the fate of magnetization-induced Shapiro steps in the
+presence of dissipation both from our analytical results and via numerical
+solution of the coupled LLG equations. We discuss experiments which can test
+our theory.",1703.07717v3
+2017-04-19,Integrating optimization with thermodynamics and plant physiology for crop ideotype design,"A computational framework integrating optimization algorithms, parallel
+computing and plant physiology was developed to explore crop ideotype design.
+The backbone of the framework is a plant physiology model that accurately
+tracks water use (i.e. a plant hydraulic model) coupled with mass transport
+(CO2 exchange and transport), energy conversion (leaf temperature due to
+radiation, convection and mass transfer) and photosynthetic biochemistry of an
+adult maize plant. For a given trait configuration, soil parameters and hourly
+weather data, the model computes water use and photosynthetic output over the
+life of an adult maize plant. We coupled this validated model with a parallel,
+meta-heuristic optimization algorithm, specifically a genetic algorithm (GA),
+to identify trait sets (ideotypes) that resulted in desired water use behavior
+of the adult maize plant. We detail features of the model as well as the
+implementation details of the coupling with the optimization framework and
+deployment on high performance computing platforms. We illustrate a
+representative result of this framework by identifying maize ideotypes with
+optimized photosynthetic yields using weather and soil conditions corresponding
+to Davis, CA. Finally, we show how the framework can be used to identify broad
+ideotype trends that can inform breeding efforts. The developed presented tool
+has the potential to inform the development of future climate-resilient crops.",1704.05885v1
+2017-04-28,From deep inelastic scattering to heavy-flavor semi-leptonic decays: Total rates into multi-hadron final states from lattice QCD,"We present a new technique for extracting decay and transition rates into
+final states with any number of hadrons. The approach is only sensitive to
+total rates, in which all out-states with a given set of QCD quantum numbers
+are included. For processes involving photons or leptons, differential rates
+with respect to the non-hadronic kinematics may also be extracted. Our method
+involves constructing a finite-volume Euclidean four-point function, whose
+corresponding spectral function measures the decay and transition rates in the
+infinite-volume limit. This requires solving the inverse problem of extracting
+the spectral function from the correlator and also necessitates a smoothing
+procedure so that a well-defined infinite-volume limit exists. Both of these
+steps are accomplished by the Backus-Gilbert method and, as we show with a
+numerical example, reasonable precision can be expected in cases with multiple
+open decay channels. Potential applications include nucleon structure functions
+and the onset of the deep inelastic scattering regime, as well as semi-leptonic
+$D$ and $B$ decay rates.",1704.08993v2
+2017-05-01,Measuring galaxy cluster masses with CMB lensing using a Maximum Likelihood estimator: Statistical and systematic error budgets for future experiments,"We develop a Maximum Likelihood estimator (MLE) to measure the masses of
+galaxy clusters through the impact of gravitational lensing on the temperature
+and polarization anisotropies of the cosmic microwave background (CMB). We show
+that, at low noise levels in temperature, this optimal estimator outperforms
+the standard quadratic estimator by a factor of two. For polarization, we show
+that the Stokes Q/U maps can be used instead of the traditional E- and B-mode
+maps without losing information. We test and quantify the bias in the recovered
+lensing mass for a comprehensive list of potential systematic errors. Using
+realistic simulations, we examine the cluster mass uncertainties from
+CMB-cluster lensing as a function of an experiment's beam size and noise level.
+We predict the cluster mass uncertainties will be 3 - 6% for SPT-3G, AdvACT,
+and Simons Array experiments with 10,000 clusters and less than 1% for the
+CMB-S4 experiment with a sample containing 100,000 clusters. The mass
+constraints from CMB polarization are very sensitive to the experimental beam
+size and map noise level: for a factor of three reduction in either the beam
+size or noise level, the lensing signal-to-noise improves by roughly a factor
+of two.",1705.00411v2
+2017-05-03,Current driven second harmonic domain wall resonance in ferromagnetic metal/ nonmagnetic metal bilayer: a field-free method for spin Hall angle measurements,"We study the ac current-driven domain wall motion in bilayer ferromagnetic
+metal (FM)/nonmagnetic metal (NM) nanowire. The solution of the modified
+Landau-Lifshitz-Gilbert equation including all the spin transfer torques is
+used to describe motion of the domain wall in presence of the spin Hall effect.
+We show that the domain wall center has second harmonic frequency response in
+addition to the known first harmonic excitation. In contrast to the
+experimentally observed second harmonic response in harmonic Hall measurements
+of spin-orbit torque in magnetic thin films, this second harmonic response
+directly originates from spin-orbit torque driven domain wall dynamics. Based
+on the spin current generated by domain wall dynamics, the longitudinal spin
+motive force generated voltage across the length of the nanowire is determined.
+The second harmonic response introduces additionally a new practical field-free
+and all-electrical method to probe the effective spin Hall angle for FM/NM
+bilayer structures that could be applied in experiments. Our results also
+demonstrate the capability of utilizing FM/NM bilayer structure in domain wall
+based spin torque signal generators and resonators.",1705.01355v5
+2017-05-20,SVM via Saddle Point Optimization: New Bounds and Distributed Algorithms,"We study two important SVM variants: hard-margin SVM (for linearly separable
+cases) and $\nu$-SVM (for linearly non-separable cases). We propose new
+algorithms from the perspective of saddle point optimization. Our algorithms
+achieve $(1-\epsilon)$-approximations with running time $\tilde{O}(nd+n\sqrt{d
+/ \epsilon})$ for both variants, where $n$ is the number of points and $d$ is
+the dimensionality. To the best of our knowledge, the current best algorithm
+for $\nu$-SVM is based on quadratic programming approach which requires
+$\Omega(n^2 d)$ time in worst case~\cite{joachims1998making,platt199912}. In
+the paper, we provide the first nearly linear time algorithm for $\nu$-SVM. The
+current best algorithm for hard margin SVM achieved by Gilbert
+algorithm~\cite{gartner2009coresets} requires $O(nd / \epsilon )$ time. Our
+algorithm improves the running time by a factor of $\sqrt{d}/\sqrt{\epsilon}$.
+Moreover, our algorithms can be implemented in the distributed settings
+naturally. We prove that our algorithms require $\tilde{O}(k(d
++\sqrt{d/\epsilon}))$ communication cost, where $k$ is the number of clients,
+which almost matches the theoretical lower bound. Numerical experiments support
+our theory and show that our algorithms converge faster on high dimensional,
+large and dense data sets, as compared to previous methods.",1705.07252v4
+2017-06-15,On the Maximum Size of Block Codes Subject to a Distance Criterion,"We establish a general formula for the maximum size of finite length block
+codes with minimum pairwise distance no less than $d$. The achievability
+argument involves an iterative construction of a set of radius-$d$ balls, each
+centered at a codeword. We demonstrate that the number of such balls that cover
+the entire code alphabet cannot exceed this maximum size. Our approach can be
+applied to codes $i)$ with elements over arbitrary code alphabets, and $ii)$
+under a broad class of distance measures, thereby ensuring the generality of
+our formula. Our formula indicates that the maximum code size can be fully
+characterized by the cumulative distribution function of the distance measure
+evaluated at two independent and identically distributed random codewords. When
+the two random codewords assume a uniform distribution over the entire code
+alphabet, our formula recovers and obtains a natural generalization of the
+Gilbert-Varshamov (GV) lower bound. We also establish a general formula for the
+zero-error capacity of any sequence of channels. Finally, we extend our study
+to the asymptotic setting, where we establish first- and second-order bounds on
+the asymptotic code rate subject to a normalized minimum distance constraint.",1706.04709v2
+2017-06-19,Capability of Detecting Ultra-Violet Counterparts of Gravitational Waves with GLUV,"With the discovery of gravitational waves (GW), attention has turned towards
+detecting counterparts to these sources. In discussions on counterpart
+signatures and multi-messenger follow-up strategies to GW detections,
+ultra-violet (UV) signatures have largely been neglected, due to UV facilities
+being limited to SWIFT, which lacks high-cadence UV survey capabilities. In
+this paper, we examine the UV signatures from merger models for the major GW
+sources, highlighting the need for further modelling, while presenting
+requirements and a design for an effective UV survey telescope. Using $u'$-band
+models as an analogue, we find that a UV survey telescope requires a limiting
+magnitude of m$_{u'}\rm (AB)\approx 24$ to fully complement the aLIGO range and
+sky localisation. We show that a network of small, balloon-based UV telescopes
+with a primary mirror diameter of 30~cm could be capable of covering the aLIGO
+detection distance from $\sim$60--100\% for BNS events and $\sim$40\% for BHNS
+events. The sensitivity of UV emission to initial conditions suggests that a UV
+survey telescope would provide a unique dataset, that can act as an effective
+diagnostic to discriminate between models.",1706.06106v2
+2017-07-27,LCD codes over ${\mathbb F}_q $ are as good as linear codes for q at least four,"The hull $H(C)$ of a linear code $C$ is defined by $H(C)=C \cap C^\perp$. A
+linear code with a complementary dual (LCD) is a linear code with $H(C)=\{0\}$.
+The dimension of the hull of a code is an invariant under permutation
+equivalence. For binary and ternary codes the dimension of the hull is also
+invariant under monomial equivalence and we show that this invariant is
+determined by the extended weight enumerator of the code.\\ The hull of a code
+is not invariant under monomial equivalence if $q\geq 4$. We show that every
+${\mathbb F}_q $-linear code is monomial equivalent with an LCD code in case $q
+\geq 4$. The proof uses techniques from Gr\""obner basis theory. We conclude
+that if there exists an ${\mathbb F}_q $-linear code with parameters
+$[n,k,d]_q$ and $q \geq 4$, then there exists also a LCD code with the same
+parameters. Hence this holds for optimal and MDS codes. In particular there
+exist LCD codes that are above the Gilbert-Varshamov bound if $q$ is a square
+and $q\geq 49$ by the existence of such codes that are algebraic geometric.\\
+Similar results are obtained with respect to Hermitian LCD codes.",1707.08856v1
+2017-08-04,Energy release in the solar atmosphere from a stream of infalling prominence debris,"Recent high-resolution and high-cadence EUV imaging has revealed a new
+phenomenon, impacting prominence debris, where prominence material from failed
+or partial eruptions can impact the lower atmosphere, releasing energy. We
+report a clear example of energy release and EUV brightening due to infalling
+prominence debris that occurred on 2011 September 7-8. The initial eruption of
+material was associated with an X1.8-class flare from AR11283, occurring at
+22:30 UT on 2011 September 7. Subsequently, a semi-continuous stream of this
+material returned to the solar surface with a velocity v > 150 km/s, impacting
+a region remote from the original active region between 00:20 - 00:40 UT on
+2011 September 8. Using SDO/AIA, the differential emission measure of the
+plasma was estimated throughout this brightening event. We found that the
+radiated energy of the impacted plasma was L_rad ~10^27 ergs, while the thermal
+energy peaked at ~10^28 ergs. From this we were able to determine the mass
+content of the debris to be in the range 2x10^14 < m < 2x10^15 g. Given typical
+promimence masses, the likely debris mass is towards the lower end of this
+range. This clear example of a prominence debris event shows that significant
+energy release takes place during these events, and that such impacts may be
+used as a novel diagnostic tool for investigating prominence material
+properties.",1708.01555v2
+2017-08-16,Magneto Acoustic Spin Hall Oscillators,"This paper introduces a novel oscillator that combines the tunability of spin
+Hall-driven nano oscillators with the high quality factor (Q) of high overtone
+bulk acoustic wave resonators (HBAR), integrating both reference and tunable
+oscillators on the same chip with CMOS. In such magneto acoustic spin Hall
+(MASH) oscillators, voltage oscillations across the magnetic tunnel junction
+(MTJ) that arise from a spin-orbit torque (SOT) are shaped by the transmission
+response of the HBAR that acts as a multiple peak-bandpass filter and a delay
+element due to its large time constant, providing delayed feedback. The
+filtered voltage oscillations can be fed back to the MTJ via a) strain, b)
+current, or c) magnetic field. We develop a SPICE-based circuit model by
+combining experimentally benchmarked models including the stochastic
+Landau-Lifshitz-Gilbert (sLLG) equation for magnetization dynamics and the
+Butterworth Van Dyke (BVD) circuit for the HBAR. Using the self-consistent
+model, we project up to $\sim$ 50X enhancement in the oscillator linewidth with
+Q reaching up to 52825 at 3 GHz, while preserving the tunability by locking the
+STNO to the nearest high Q peak of the HBAR. We expect that our results will
+inspire MEMS-based solutions to spintronic devices by combining attractive
+features of both fields for a variety of applications.",1708.04735v2
+2017-09-01,An order optimal policy for exploiting idle spectrum in cognitive radio networks,"In this paper a spectrum sensing policy employing recency-based exploration
+is proposed for cognitive radio networks. We formulate the problem of finding a
+spectrum sensing policy for multi-band dynamic spectrum access as a stochastic
+restless multi-armed bandit problem with stationary unknown reward
+distributions. In cognitive radio networks the multi-armed bandit problem
+arises when deciding where in the radio spectrum to look for idle frequencies
+that could be efficiently exploited for data transmission. We consider two
+models for the dynamics of the frequency bands: 1) the independent model where
+the state of the band evolves randomly independently from the past and 2) the
+Gilbert-Elliot model, where the states evolve according to a 2-state Markov
+chain. It is shown that in these conditions the proposed sensing policy attains
+asymptotically logarithmic weak regret. The policy proposed in this paper is an
+index policy, in which the index of a frequency band is comprised of a sample
+mean term and a recency-based exploration bonus term. The sample mean promotes
+spectrum exploitation whereas the exploration bonus encourages for further
+exploration for idle bands providing high data rates. The proposed recency
+based approach readily allows constructing the exploration bonus such that it
+will grow the time interval between consecutive sensing time instants of a
+suboptimal band exponentially, which then leads to logarithmically increasing
+weak regret. Simulation results confirming logarithmic weak regret are
+presented and it is found that the proposed policy provides often improved
+performance at low complexity over other state-of-the-art policies in the
+literature.",1709.00237v1
+2017-09-08,EndoSensorFusion: Particle Filtering-Based Multi-sensory Data Fusion with Switching State-Space Model for Endoscopic Capsule Robots,"A reliable, real time multi-sensor fusion functionality is crucial for
+localization of actively controlled capsule endoscopy robots, which are an
+emerging, minimally invasive diagnostic and therapeutic technology for the
+gastrointestinal (GI) tract. In this study, we propose a novel multi-sensor
+fusion approach based on a particle filter that incorporates an online
+estimation of sensor reliability and a non-linear kinematic model learned by a
+recurrent neural network. Our method sequentially estimates the true robot pose
+from noisy pose observations delivered by multiple sensors. We experimentally
+test the method using 5 degree-of-freedom (5-DoF) absolute pose measurement by
+a magnetic localization system and a 6-DoF relative pose measurement by visual
+odometry. In addition, the proposed method is capable of detecting and handling
+sensor failures by ignoring corrupted data, providing the robustness expected
+of a medical device. Detailed analyses and evaluations are presented using
+ex-vivo experiments on a porcine stomach model prove that our system achieves
+high translational and rotational accuracies for different types of endoscopic
+capsule robot trajectories.",1709.03401v3
+2017-09-12,Distributed Scheduling in Time Dependent Environments: Algorithms and Analysis,"Consider the problem of a multiple access channel in a time dependent
+environment with a large number of users. In such a system, mostly due to
+practical constraints (e.g., decoding complexity), not all users can be
+scheduled together, and usually only one user may transmit at any given time.
+Assuming a distributed, opportunistic scheduling algorithm, we analyse the
+system's properties, such as delay, QoS and capacity scaling laws.
+Specifically, we start with analyzing the performance while \emph{assuming the
+users are not necessarily fully backlogged}, focusing on the queueing problem
+and, especially, on the \emph{strong dependence between the queues}. We first
+extend a known queueing model by Ephremides and Zhu, to give new results on the
+convergence of the probability of collision to its average value (as the number
+of users grows), and hence for the ensuing system performance metrics, such as
+throughput and delay. This model, however, is limited in the number of users
+one can analyze. We thus suggest a new model, which is much simpler yet can
+accurately describes the system behaviour when the number of users is large.
+  We then proceed to the analysis of this system under the assumption of time
+dependent channels. Specifically, we assume each user experiences a different
+channel state sequence, expressing different channel fluctuations
+(specifically, the Gilbert-Elliott model). The system performance under this
+setting is analysed, along with the channel capacity scaling laws.",1709.04361v1
+2017-09-16,A differential memristive synapse circuit for on-line learning in neuromorphic computing systems,"Spike-based learning with memristive devices in neuromorphic computing
+architectures typically uses learning circuits that require overlapping pulses
+from pre- and post-synaptic nodes. This imposes severe constraints on the
+length of the pulses transmitted in the network, and on the network's
+throughput. Furthermore, most of these circuits do not decouple the currents
+flowing through memristive devices from the one stimulating the target neuron.
+This can be a problem when using devices with high conductance values, because
+of the resulting large currents. In this paper we propose a novel circuit that
+decouples the current produced by the memristive device from the one used to
+stimulate the post-synaptic neuron, by using a novel differential scheme based
+on the Gilbert normalizer circuit. We show how this circuit is useful for
+reducing the effect of variability in the memristive devices, and how it is
+ideally suited for spike-based learning mechanisms that do not require
+overlapping pre- and post-synaptic pulses. We demonstrate the features of the
+proposed synapse circuit with SPICE simulations, and validate its learning
+properties with high-level behavioral network simulations which use a
+stochastic gradient descent learning rule in two classification tasks.",1709.05484v1
+2017-09-21,Impacts of Surface Depletion on the Plasmonic Properties of Doped Semiconductor Nanocrystals,"Degenerately doped semiconductor nanocrystals (NCs) exhibit a localized
+surface plasmon resonance (LSPR) in the infrared range of the electromagnetic
+spectrum. Unlike metals, semiconductor NCs offer tunable LSPR characteristics
+enabled by doping, or via electrochemical or photochemical charging. Tuning
+plasmonic properties through carrier density modulation suggests potential
+applications in smart optoelectronics, catalysis, and sensing. Here, we
+elucidate fundamental aspects of LSPR modulation through dynamic carrier
+density tuning in Sn-doped Indium Oxide NCs. Monodisperse Sn-doped Indium Oxide
+NCs with various doping level and sizes were synthesized and assembled in
+uniform films. NC films were then charged in an in situ electrochemical cell
+and the LSPR modulation spectra were monitored. Based on spectral shifts and
+intensity modulation of the LSPR, combined with optical modeling, it was found
+that often-neglected semiconductor properties, specifically band structure
+modification due to doping and surface states, strongly affect LSPR modulation.
+Fermi level pinning by surface defect states creates a surface depletion layer
+that alters the LSPR properties; it determines the extent of LSPR frequency
+modulation, diminishes the expected near field enhancement, and strongly
+reduces sensitivity of the LSPR to the surroundings.",1709.07136v2
+2017-10-05,Transport theory for femtosecond laser-induced spin-transfer torques,"Ultrafast demagnetization of magnetic layers pumped by a femtosecond laser
+pulse is accompanied by a nonthermal spin-polarized current of hot electrons.
+These spin currents are studied here theoretically in a spin valve with
+noncollinear magnetizations. To this end, we introduce an extended model of
+superdiffusive spin transport that enables to treat noncollinear magnetic
+configurations, and apply it to the perpendicular spin valve geometry. We show
+how spin-transfer torques arise due to this mechanism and calculate their
+action on the magnetization present, as well as how the latter depends on the
+thicknesses of the layers and other transport parameters. We demonstrate that
+there exists a certain optimum thickness of the out-of-plane magnetized
+spin-current polarizer such that the torque acting on the second magnetic layer
+is maximal. Moreover, we study the magnetization dynamics excited by the
+superdiffusive spin-transfer torque due to the flow of hot electrons employing
+the Landau-Lifshitz-Gilbert equation. Thereby we show that a femtosecond laser
+pulse applied to one magnetic layer can excite small-angle precessions of the
+magnetization in the second magnetic layer. We compare our calculations with
+recent experimental results.",1710.02083v2
+2017-10-12,A critical comparison of methods for the determination of the ageing sensitivity in biomedical grade yttria stabilized zirconia,"Since the recent failure events of two particular series of zirconia femoral
+heads for total hip replacement prosthesis, a large decrease in the use of
+zirconia ceramics for orthopaedic implants has been observed. In spite of the
+biomedical success of this material during the last ten years, this was
+required for safety reasons, until the cause of the failures is known. It has
+been shown that these failures were related to the low temperature hydrothermal
+degradation (also known as ageing). Thus it is crucial to better understand the
+ageing behaviour, in order to be able to assess its importance and then control
+it if required. In this paper, various techniques relevant to assess the
+hydrothermal degradation sensitivity of biomedical grade yttria stabilized
+zirconia are discussed and compared. The expected outputs of conventional
+methods, i.e. X-Ray diffraction and scanning electron microscopy are examined.
+More recent methods like optical interferometry and atomic force microscopy are
+presented, with their respective benefits and drawbacks. An up to date
+comparison of these different techniques is provided, and their use for
+ensuring the long term reliability of a particular batch of zirconia in terms
+of ageing degradation is demonstrated.",1710.04449v1
+2017-10-26,Evaluation of Treatment Effect Modification by Biomarkers Measured Pre- and Post-randomization in the Presence of Non-monotone Missingness,"In vaccine studies, investigators are often interested in studying effect
+modifiers of clinical treatment efficacy by biomarker-based principal strata,
+which is useful for selecting biomarker study endpoints for evaluating
+treatments in new trials, exploring biological mechanisms of clinical treatment
+efficacy, and studying mediators of clinical treatment efficacy. However, in
+trials where participants may enter the study with prior exposure therefore
+with variable baseline biomarker values, clinical treatment efficacy may depend
+jointly on a biomarker measured at baseline and measured at a fixed time after
+vaccination. Therefore, it is of interest to conduct a bivariate effect
+modification analysis by biomarker-based principal strata and baseline
+biomarker values. Previous methods allow this assessment if participants who
+have the biomarker measured at the the fixed time point post randomization
+would also have the biomarker measured at baseline. However, additional
+complications in study design could happen in practice. For example, in the
+Dengue correlates study, baseline biomarker values were only available from a
+fraction of participants who have biomarkers measured post-randomization. How
+to conduct the bivariate effect modification analysis in these studies remains
+an open research question. In this article, we propose an estimated likelihood
+method to utilize the sub-sampled baseline biomarker in the effect modification
+analysis and illustrate our method with datasets from two dengue phase 3
+vaccine efficacy trials.",1710.09923v1
+2017-10-29,"If it ain't broke, don't fix it: Sparse metric repair","Many modern data-intensive computational problems either require, or benefit
+from distance or similarity data that adhere to a metric. The algorithms run
+faster or have better performance guarantees. Unfortunately, in real
+applications, the data are messy and values are noisy. The distances between
+the data points are far from satisfying a metric. Indeed, there are a number of
+different algorithms for finding the closest set of distances to the given ones
+that also satisfy a metric (sometimes with the extra condition of being
+Euclidean). These algorithms can have unintended consequences, they can change
+a large number of the original data points, and alter many other features of
+the data.
+  The goal of sparse metric repair is to make as few changes as possible to the
+original data set or underlying distances so as to ensure the resulting
+distances satisfy the properties of a metric. In other words, we seek to
+minimize the sparsity (or the $\ell_0$ ""norm"") of the changes we make to the
+distances subject to the new distances satisfying a metric. We give three
+different combinatorial algorithms to repair a metric sparsely. In one setting
+the algorithm is guaranteed to return the sparsest solution and in the other
+settings, the algorithms repair the metric. Without prior information, the
+algorithms run in time proportional to the cube of the number of input data
+points and, with prior information we can reduce the running time considerably.",1710.10655v1
+2017-12-06,Monitoring the orientation of rare-earth-doped nanorods for flow shear tomography,"Rare-earth phosphors exhibit unique luminescence polarization features
+originating from the anisotropic symmetry of the emitter ion's chemical
+environment. However, to take advantage of this peculiar property, it is
+necessary to control and measure the ensemble orientation of the host particles
+with a high degree of precision. Here, we show a methodology to obtain the
+photoluminescence polarization of Eu-doped LaPO4 nano rods assembled in an
+electrically modulated liquid-crystalline phase. We measure Eu3+ emission
+spectra for the three main optimal configurations ({\sigma}, {\pi} and
+{\alpha}, depending on the direction of observation and the polarization axes)
+and use them as a reference for the nano rod orientation analysis. Based on the
+fact that flowing nano rods tend to orient along the shear strain profile, we
+use this orientation analysis to measure the local shear rate in a flowing
+liquid. The potential of this approach is then demonstrated through tomographic
+imaging of the shear rate distribution in a microfluidic system.",1712.02191v1
+2017-12-08,Shrewd Selection Speeds Surfing: Use Smart EXP3!,"In this paper, we explore the use of multi-armed bandit online learning
+techniques to solve distributed resource selection problems. As an example, we
+focus on the problem of network selection. Mobile devices often have several
+wireless networks at their disposal. While choosing the right network is vital
+for good performance, a decentralized solution remains a challenge. The
+impressive theoretical properties of multi-armed bandit algorithms, like EXP3,
+suggest that it should work well for this type of problem. Yet, its real-word
+performance lags far behind. The main reasons are the hidden cost of switching
+networks and its slow rate of convergence. We propose Smart EXP3, a novel
+bandit-style algorithm that (a) retains the good theoretical properties of
+EXP3, (b) bounds the number of switches, and (c) yields significantly better
+performance in practice. We evaluate Smart EXP3 using simulations, controlled
+experiments, and real-world experiments. Results show that it stabilizes at the
+optimal state, achieves fairness among devices and gracefully deals with
+transient behaviors. In real world experiments, it can achieve 18% faster
+download over alternate strategies. We conclude that multi-armed bandit
+algorithms can play an important role in distributed resource selection
+problems, when practical concerns, such as switching costs and convergence
+time, are addressed.",1712.03038v3
+2017-12-08,Qatar Exoplanet Survey: Qatar-6b -- a grazing transiting hot Jupiter,"We report the discovery of Qatar-6b, a new transiting planet identified by
+the Qatar Exoplanet Survey (QES). The planet orbits a relatively bright
+(V=11.44), early-K main-sequence star at an orbital period of P~3.506 days. An
+SED fit to available multi-band photometry, ranging from the near-UV to the
+mid-IR, yields a distance of d = 101 +/- 6 pc to the system. From a global fit
+to follow-up photometric and spectroscopic observations, we calculate the mass
+and radius of the planet to be Mp = 0.67 +/- 0.07 Mjup and Rp = 1.06 +/- 0.07
+Rjup, respectively. We use multi-color photometric light curves to show that
+the transit is grazing, making Qatar-6b one of the few exoplanets known in a
+grazing transit configuration. It adds to the short list of targets that offer
+the best opportunity to look for additional bodies in the host planetary system
+through variations in the transit impact factor and duration.",1712.03216v1
+2018-01-25,"Generating survival times using Cox proportional hazards models with cyclic time-varying covariates, with application to a multiple-dose monoclonal antibody clinical trial","In two harmonized efficacy studies to prevent HIV infection through multiple
+infusions of the monoclonal antibody VRC01, a key objective is to evaluate
+whether the serum concentration of VRC01, which changes cyclically over time
+along with the infusion schedule, is associated with the rate of HIV infection.
+Simulation studies are needed in the development of such survival models. In
+this paper, we consider simulating event time data with a continuous
+time-varying covariate whose values vary with time through multiple drug
+administration cycles, and whose effect on survival changes differently before
+and after a threshold within each cycle. The latter accommodates settings with
+a zero-protection biomarker threshold above which the drug provides a varying
+level of protection depending on the biomarker level, but below which the drug
+provides no protection. We propose two simulation approaches: one based on
+simulating survival data under a single-dose regimen first before data are
+aggregated over multiple doses, and another based on simulating survival data
+directly under a multiple-dose regimen. We generate time-to-event data
+following a Cox proportional hazards model based on inverting the cumulative
+hazard function and a log link function for relating the hazard function to the
+covariates. The method's validity is assessed in two sets of simulation
+experiments. The results indicate that the proposed procedures perform well in
+producing data that conform to their cyclic nature and assumptions of the Cox
+proportional hazards model.",1801.08248v1
+2018-01-29,Band-pass superlattice magnetic tunnel junctions,"Significant scientific and technological progress in the field of spintronics
+is based on trilayer magnetic tunnel junction devices which principally rely on
+the physics of single barrier tunneling. While technologically relevant devices
+have been prototyped, the physics of single barrier tunneling poses ultimate
+limitations on the performance of magnetic tunnel junction devices. Here, we
+propose a fresh route toward high performance magnetic tunnel junctions by
+making electronic analogs of optical phenomena such as anti-reflections and
+Fabry-P\`erot resonances. The devices we propose feature anti-reflection
+enabled superlattice heterostructures sandwiched between the fixed and the free
+ferromagnets of the magnetic tunnel junction structure. Our predictions are
+based on the non-equilibrium Green's function spin transport formalism coupled
+self-consistently with the Landau-Lifshitz-Gilbert-Slonczewski equation. Owing
+to the physics of bandpass spin filtering in the bandpass superlattice magnetic
+tunnel junction device, we demonstrate an ultra-high boost in the tunnel
+magneto-resistance (TMR$\approx5\times10^4\%$) and nearly 92% suppression of
+spin transfer torque switching bias in comparison to a traditional trilayer
+magnetic tunnel junction device. We rationalize improvised spin transfer torque
+switching via analysis of the Slonczewski spin current transmission spectra.
+The proof of concepts presented here can lead to next-generation spintronics
+device design harvesting the rich physics of superlattice heterostructures and
+exploiting spintronic analogs of optical phenomena.",1801.09409v2
+2018-01-29,Theory of AC quantum transport with fully electrodynamic coupling,"With the continued scaling of microelectronic devices along with the growing
+demand of high-speed wireless telecommunications technologies, there is
+increasing need for high-frequency device modeling techniques that accurately
+capture the quantum mechanical nature of charge transport in nanoscale devices
+along with the dynamic fields that are generated. In an effort to fill this
+gap, we develop a simulation methodology that self-consistently couples AC
+non-equilibrium Green functions (NEGF) with the full solution of Maxwell's
+equations in the frequency domain. We apply this technique to simulate
+radiation from a quantum-confined, quarter-wave, monopole antenna where the
+length $L$ is equal to one quarter of the wavelength, $\lambda_0$. Classically,
+such an antenna would have a narrower, more directed radiation pattern compared
+to one with $L \ll \lambda_0$, but we find that a quantum quarter-wave antenna
+has no directivity gain compared to the classical solution. We observe that the
+quantized wave function within the antenna significantly alter the charge and
+current density distribution along the length of the wire, which in turn
+modifies the far-field radiation pattern from the antenna. These results show
+that high-frequency radiation from quantum systems can be markedly different
+from classical expectations. Our method, therefore, will enable accurate
+modeling of the next generation of high-speed nanoscale electronic devices.",1801.09611v1
+2018-02-17,Design and Implementation of the Andromeda Proof Assistant,"Andromeda is an LCF-style proof assistant where the user builds derivable
+judgments by writing code in a meta-level programming language AML. The only
+trusted component of Andromeda is a minimalist nucleus (an implementation of
+the inference rules of an object-level type theory), which controls
+construction and decomposition of type-theoretic judgments.
+  Since the nucleus does not perform complex tasks like equality checking
+beyond syntactic equality, this responsibility is delegated to the user, who
+implements one or more equality checking procedures in the meta-language. The
+AML interpreter requests witnesses of equality from user code using the
+mechanism of algebraic operations and handlers. Dynamic checks in the nucleus
+guarantee that no invalid object-level derivations can be constructed. %even if
+the AML code (or interpreter) is untrusted.
+  To demonstrate the flexibility of this system structure, we implemented a
+nucleus consisting of dependent type theory with equality reflection. Equality
+reflection provides a very high level of expressiveness, as it allows the user
+to add new judgmental equalities, but it also destroys desirable meta-theoretic
+properties of type theory (such as decidability and strong normalization).
+  The power of effects and handlers in AML is demonstrated by a standard
+library that provides default algorithms for equality checking, computation of
+normal forms, and implicit argument filling. Users can extend these new
+algorithms by providing local ""hints"" or by completely replacing these
+algorithms for particular developments. We demonstrate the resulting system by
+showing how to axiomatize and compute with natural numbers, by axiomatizing the
+untyped $\lambda$-calculus, and by implementing a simple automated system for
+managing a universe of types.",1802.06217v1
+2018-03-02,Broadband spectroscopy of thermodynamic magnetization fluctuations through a ferromagnetic spin-reorientation transition,"We use scanning optical magnetometry to study the broadband frequency spectra
+of spontaneous magnetization fluctuations, or ""magnetization noise"", in an
+archetypal ferromagnetic film that can be smoothly tuned through a spin
+reorientation transition (SRT). The SRT is achieved by laterally varying the
+magnetic anisotropy across an ultrathin Pt/Co/Pt trilayer, from the
+perpendicular to in-plane direction, via graded Ar$^+$ irradiation. In regions
+exhibiting perpendicular anisotropy, the power spectrum of the magnetization
+noise, $S(\nu)$, exhibits a remarkably robust $\nu^{-3/2}$ power law over
+frequencies $\nu$ from 1~kHz to 1~MHz. As the SRT region is traversed, however,
+$S(\nu)$ spectra develop a steadily-increasing critical frequency, $\nu_0$,
+below which the noise power is spectrally flat, indicating an evolving
+low-frequency cutoff for magnetization fluctuations. The magnetization noise
+depends strongly on applied in- and out-of-plane magnetic fields, revealing
+local anisotropies and also a field-induced emergence of fluctuations in
+otherwise stable ferromagnetic films. Finally, we demonstrate that higher-order
+correlators can be computed from the noise. These results highlight broadband
+spectroscopy of thermodynamic fluctuations as a powerful tool to characterize
+the interplay between thermal and magnetic energy scales, and as a means of
+characterizing phase transitions in ferromagnets.",1803.00962v1
+2018-03-06,On Simple Back-Off in Unreliable Radio Networks,"In this paper, we study local and global broadcast in the dual graph model,
+which describes communication in a radio network with both reliable and
+unreliable links. Existing work proved that efficient solutions to these
+problems are impossible in the dual graph model under standard assumptions. In
+real networks, however, simple back-off strategies tend to perform well for
+solving these basic communication tasks. We address this apparent paradox by
+introducing a new set of constraints to the dual graph model that better
+generalize the slow/fast fading behavior common in real networks. We prove that
+in the context of these new constraints, simple back-off strategies now provide
+efficient solutions to local and global broadcast in the dual graph model. We
+also precisely characterize how this efficiency degrades as the new constraints
+are reduced down to non-existent, and prove new lower bounds that establish
+this degradation as near optimal for a large class of natural algorithms. We
+conclude with a preliminary investigation of the performance of these
+strategies when we include additional generality to the model. These results
+provide theoretical foundations for the practical observation that simple
+back-off algorithms tend to work well even amid the complicated link dynamics
+of real radio networks.",1803.02216v3
+2018-04-12,Connectivity in Random Annulus Graphs and the Geometric Block Model,"We provide new connectivity results for {\em vertex-random graphs} or {\em
+random annulus graphs} which are significant generalizations of random
+geometric graphs. Random geometric graphs (RGG) are one of the most basic
+models of random graphs for spatial networks proposed by Gilbert in 1961,
+shortly after the introduction of the Erd\H{o}s-R\'{en}yi random graphs. They
+resemble social networks in many ways (e.g. by spontaneously creating cluster
+of nodes with high modularity). The connectivity properties of RGG have been
+studied since its introduction, and analyzing them has been significantly
+harder than their Erd\H{o}s-R\'{en}yi counterparts due to correlated edge
+formation.
+  Our next contribution is in using the connectivity of random annulus graphs
+to provide necessary and sufficient conditions for efficient recovery of
+communities for {\em the geometric block model} (GBM). The GBM is a
+probabilistic model for community detection defined over an RGG in a similar
+spirit as the popular {\em stochastic block model}, which is defined over an
+Erd\H{o}s-R\'{en}yi random graph. The geometric block model inherits the
+transitivity properties of RGGs and thus models communities better than a
+stochastic block model. However, analyzing them requires fresh perspectives as
+all prior tools fail due to correlation in edge formation. We provide a simple
+and efficient algorithm that can recover communities in GBM exactly with high
+probability in the regime of connectivity.",1804.05013v3
+2018-04-19,Equilibrium magnetization of a quasispherical cluster of single-domain particles,"Equilibrium magnetization curve of a rigid finite-size spherical cluster of
+single-domain particles is investigated both numerically and analytically. The
+spatial distribution of particles within the cluster is random. Dipole-dipole
+interactions between particles are taken into account. The particles are
+monodisperse. It is shown, using the stochastic Landau-Lifshitz-Gilbert
+equation that the magnetization of such clusters is generally lower than
+predicted by the classical Langevin model. In a broad range of dipolar coupling
+parameters and particle volume fractions, the cluster magnetization in the weak
+field limit can be successfully described by the modified mean-field theory,
+which was originally proposed for the description of concentrated ferrofluids.
+In moderate and strong fields, the theory overestimates the cluster
+magnetization. However, predictions of the theory can be improved by adjusting
+the corresponding mean-field parameter. If magnetic anisotropy of particles is
+additionally taken into account and if the distribution of the particles' easy
+axes is random and uniform, then the cluster equilibrium response is even
+weaker. The decrease of the magnetization with increasing anisotropy constant
+is more pronounced at large applied fields. The phenomenological generalization
+of the modified mean-field theory, that correctly describes this effect for
+small coupling parameters, is proposed.",1804.07196v2
+2018-05-28,Starbug fibre positioning robots: performance and reliability enhancements,"Starbugs are miniature piezoelectric walking robots that can be operated in
+parallel to position many payloads like optical fibers across a telescopes
+focal plane. They consist of two concentric piezoelectric ceramic tubes that
+walk with micron step size. In addition to individual optical fibers, Starbugs
+have moved a payload of 0.75kg at several millimeters per second. The
+Australian Astronomical Observatory previously developed prototype devices and
+tested them in the laboratory. Now we are optimizing the Starbug design for
+production and deployment in the TAIPAN instrument, which will be capable of
+configuring 300 optical fibers over a six degree field-of-view on the UK
+Schmidt Telescope within a few minutes. The TAIPAN instrument will demonstrate
+the technology and capability for MANIFEST (Many Instrument Fiber-System)
+proposed for the Giant Magellan Telescope. Design is addressing: connector
+density and voltage limitations, mechanical reliability and construction
+repeatability, field plate residues and scratching, metrology stability, and
+facilitation of improved motion in all aspects of the design for later
+evaluation. Here we present the new design features of the AAO TAIPAN Starbug.",1805.10761v1
+2018-06-14,Resolving interfacial charge transfer in titanate superlattices using resonant X-ray reflectometry,"Charge transfer in oxide heterostructures can be tuned to promote emergent
+interfacial states, and accordingly, has been the subject of intense study in
+recent years. However, accessing the physics at these interfaces, which are
+often buried deep below the sample surface, remains difficult. Addressing this
+challenge requires techniques capable of measuring the local electronic
+structure with high-resolution depth dependence. Here, we have used
+linearly-polarized resonant X-ray reflectometry (RXR) as a means to visualize
+charge transfer in oxide superlattices with atomic layer precision. From our
+RXR measurements, we extract valence depth profiles of SmTiO$_3$
+(SmTO)/SrTiO$_3$ (STO) heterostructures with STO quantum wells varying in
+thickness from 5 SrO planes down to a single, atomically thin SrO plane. At the
+polar-nonpolar SmTO/STO interface, an electrostatic discontinuity leads to
+approximately half an electron per areal unit cell transferred from the
+interfacial SmO layer into the neighboring STO quantum well. We observe this
+charge transfer as a suppression of the t$_{2g}$ absorption peaks that
+minimizes contrast with the neighboring SmTO layers at those energies and leads
+to a pronounced absence of superlattice peaks in the reflectivity data. Our
+results demonstrate the sensitivity of RXR to electronic reconstruction at the
+atomic scale, and establish RXR as a powerful means of characterizing charge
+transfer at buried oxide interfaces.",1806.05733v1
+2018-06-18,Formation Timescales for High-Mass X-ray Binaries in M33,"We have identified 55 candidate high-mass X-ray binaries (HMXBs) in M33 using
+available archival {\it HST} and {\it Chandra} imaging to find blue stars
+associated with X-ray positions. We use the {\it HST} photometric data to model
+the color-magnitude diagrams in the vicinity of each candidate HMXB to measure
+a resolved recent star formation history (SFH), and thus a formation timescale,
+or age for the source. Taken together, the SFHs for all candidate HMXBs in M33
+yield an age distribution that suggests preferred formation timescales for
+HMXBs in M33 of $<$ 5 Myr and $\sim$ 40 Myr after the initial star formation
+episode. The population at 40 Myr is seen in other Local Group galaxies, and
+can be attributed to a peak in formation efficiency of HMXBs with neutron stars
+as compact objects and B star secondary companions. This timescale is preferred
+as neutron stars should form in abundance from $\sim$ 8 M$_{\odot}$
+core-collapse progenitors on these timescales, and B stars are shown
+observationally to be most actively losing mass around this time. The young
+population at $<$ 5 Myr has not be observed in other Local Group HMXB
+population studies, but may be attributed to a population of very massive
+progenitors forming black holes very early on. We discuss these results in the
+context of massive binary evolution, and the implications for compact object
+binaries and gravitational wave sources.",1806.06863v1
+2018-06-24,Nanoscopic time crystal obtained by nonergodic spin dynamics,"We study the far-from-equilibrium properties of quenched magnetic nanoscopic
+classical spin systems. In particular, we focus on the interplay between
+lattice vibrations and magnetic frustrations induced by surface effects typical
+of an antiferromagnet. We use a combination of Monte Carlo simulations and
+explore the dynamical behaviours by solving the stochastic
+Landau-Lifshitz-Gilbert equation at finite temperature. The Monte Carlo
+approach treats both the ionic degrees of freedom and spin variables on the
+same footing, via an extended Lennard-Jones Hamiltonian with a spin-lattice
+coupling. The zero temperature phase diagram of the finite size nanoscopic
+systems with respect to the range of the Heisenberg interaction and the
+Lennard-Jones coupling constant shows two main structures with non-trivial
+magnetisation triggered by antiferromagnetism: a simple cubic and a
+body-centred cubic. At non zero temperature, the competition between spins and
+the ionic vibrations considerably affects the magnetization of the system.
+Exploring the dynamics reveals a non-trivial structural induced behaviour in
+the spin relaxation with a concomitant memory of the initially applied
+ferromagnetic quench. We report the observation of a non-trivial dynamical
+scenario, obtained after a ferromagnetic magnetic quench at low temperature.
+Furthermore, we observe long-lived non-thermal states which could open new
+avenues for nano-technology.",1806.09130v4
+2018-06-29,The warm Neptunes around HD 106315 have low stellar obliquities,"We present the obliquity of the warm Neptune HD 106315c measured via a series
+of spectroscopic transit observations. HD 106315c is a 4.4 REarth warm Neptune
+orbiting a moderately rotating late F-star with a period of 21.05 days. HD
+106315 also hosts a 2.5 REarth super-Earth on a 9.55 day orbit. Our Doppler
+tomographic analyses of four transits observed by the Magellan/MIKE, HARPS, and
+TRES facilities find HD 106315c to be in a low stellar obliquity orbit,
+consistent with being well aligned with the spin axis of the host star at
+lambda = -10 +3.6/-3.8 deg. We suggest, via dynamical N-body simulations, that
+the two planets in the system must be co-planar, and thus are both well aligned
+with the host star. HD 106315 is only the fourth warm Neptune system with
+obliquities measured. All warm Neptune systems have been found in well aligned
+geometries, consistent with the interpretation that these systems are formed
+in-situ in the inner protoplanetary disk, and also consistent with the majority
+of Kepler multi-planet systems that are in low obliquity orbits. With a transit
+depth of 1.02 mmag, HD 106315c is among the smallest planets to have been
+detected in transit spectroscopy, and we discuss its detection in the context
+of TESS and the next generations of spectrographs.",1807.00024v1
+2018-07-13,"BFORE: A CMB Balloon Payload to Measure Reionization, Neutrino Mass, and Cosmic Inflation","BFORE is a high-altitude ultra-long-duration balloon mission to map the
+cosmic microwave background (CMB). During a 28-day mid-latitude flight launched
+from Wanaka, New Zealand, the instrument will map half the sky to improve
+measurements of the optical depth to reionization tau. This will break
+parameter degeneracies needed to detect neutrino mass. BFORE will also hunt for
+the gravitational wave B-mode signal, and map Galactic dust foregrounds. The
+mission will be the first near-space use of TES/mSQUID multichroic detectors
+(150/217 GHz and 280/353 GHz bands) with low-power readout electronics.",1807.05215v1
+2018-07-19,Unsupervised Metric Learning in Presence of Missing Data,"For many machine learning tasks, the input data lie on a low-dimensional
+manifold embedded in a high dimensional space and, because of this
+high-dimensional structure, most algorithms are inefficient. The typical
+solution is to reduce the dimension of the input data using standard dimension
+reduction algorithms such as ISOMAP, LAPLACIAN EIGENMAPS or LLES. This
+approach, however, does not always work in practice as these algorithms require
+that we have somewhat ideal data. Unfortunately, most data sets either have
+missing entries or unacceptably noisy values. That is, real data are far from
+ideal and we cannot use these algorithms directly. In this paper, we focus on
+the case when we have missing data. Some techniques, such as matrix completion,
+can be used to fill in missing data but these methods do not capture the
+non-linear structure of the manifold. Here, we present a new algorithm
+MR-MISSING that extends these previous algorithms and can be used to compute
+low dimensional representation on data sets with missing entries. We
+demonstrate the effectiveness of our algorithm by running three different
+experiments. We visually verify the effectiveness of our algorithm on synthetic
+manifolds, we numerically compare our projections against those computed by
+first filling in data using nlPCA and mDRUR on the MNIST data set, and we also
+show that we can do classification on MNIST with missing data. We also provide
+a theoretical guarantee for MR-MISSING under some simplifying assumptions.",1807.07610v3
+2018-08-09,Four new eclipsing mid M-dwarf systems from the New Luyten Two Tenths catalog,"Using data from the MEarth-North and MEarth-South transit surveys, we present
+the detection of eclipses in four mid M-dwarf systems: LP 107-25, LP 261-75, LP
+796-24, and LP 991-15. Combining the MEarth photometry with spectroscopic
+follow-up observations, we show that LP 107-25 and LP 796-24 are short-period
+(1.388 and 0.523 day, respectively) eclipsing binaries in triple-lined systems
+with substantial third light contamination from distant companions. LP 261-75
+is a short-period (1.882 day) single-lined system consisting of a mid M-dwarf
+eclipsed by a probable brown dwarf secondary, with another distant visual brown
+dwarf companion. LP 991-15 is a long-period (29.3 day) double-lined eclipsing
+binary on an eccentric orbit with a geometry which produces only primary
+eclipses. A spectroscopic orbit is given for LP 991-15, and initial orbits for
+LP 107-25 and LP 261-75.",1808.03243v1
+2018-08-14,"Addressing Johnson graphs, complete multipartite graphs, odd cycles and other graphs","Graham and Pollak showed that the vertices of any graph $G$ can be addressed
+with $N$-tuples of three symbols, such that the distance between any two
+vertices may be easily determined from their addresses. An addressing is
+optimal if its length $N$ is minimum possible.
+  In this paper, we determine an addressing of length $k(n-k)$ for the Johnson
+graphs $J(n,k)$ and we show that our addressing is optimal when $k=1$ or when
+$k=2, n=4,5,6$, but not when $n=6$ and $k=3$. We study the addressing problem
+as well as a variation of it in which the alphabet used has more than three
+symbols, for other graphs such as complete multipartite graphs and odd cycles.
+We also present computations describing the distribution of the minimum length
+of addressings for connected graphs with up to $10$ vertices. Motivated by
+these computations we settle a problem of Graham, showing that most graphs on
+$n$ vertices have an addressing of length at most $n-(2-o(1))\log_2 n$.",1808.04757v2
+2018-09-26,On Bioelectric Algorithms: A Novel Application of Theoretical Computer Science to Core Problems in Developmental Biology,"Cellular bioelectricity describes the biological phenomenon in which cells in
+living tissue generate and maintain patterns of voltage gradients induced by
+differing concentrations of charged ions. A growing body of research suggests
+that bioelectric patterns represent an ancient system that plays a key role in
+guiding many important developmental processes including tissue regeneration,
+tumor suppression, and embryogenesis. Understanding the relationship between
+high-level bioelectric patterns and low-level biochemical processes might also
+enable powerful new forms of synthetic biology. A key open question in this
+area is understanding how a collection of cells, interacting with each other
+and the extracellular environment only through simple ligand bindings and ion
+fluxes, can compute non-trivial patterns and perform non-trivial information
+processing tasks. The standard approach to this question is to model a given
+bioelectrical network as a system of differential equations and then explore
+its behavior using simulation techniques. In this paper, we propose applying a
+computational approach. In more detail, we present the cellular bioelectric
+model (CBM), a new computational model that captures the primary capabilities
+and constraints of bioelectric interactions between cells and their
+environment. We use this model to investigate several important topics in
+cellular bioelectricity, including symmetry breaking and information
+processing. Among other results, we describe and analyze a basic bioelectric
+strategy the efficiently stabilizes arbitrary cell networks into maximal
+independent sets (a structure known to play a role in the nervous system
+development of flys), and prove cells in our model are Turing complete in their
+ability to process information encoded in their initial voltage potential.",1809.10046v1
+2018-10-02,Floquet engineering of classical systems,"We develop the Floquet-Magnus expansion for a classical equation of motion
+under a periodic drive that is applicable to both isolated and open systems.
+For classical systems, known approaches based on the Floquet theorem fail due
+to the nonlinearity and the stochasticity of their equations of motion (EOMs)
+in contrast to quantum ones. Here, employing their master equation, we
+successfully extend the Floquet methodology to classical EOMs to obtain their
+Floquet-Magnus expansions, thereby overcoming this difficulty. Our method has a
+wide range of application from classical to quantum as long as they are
+described by differential equations including the Langevin equation, the
+Gross-Pitaevskii equation, and the time-dependent Ginzburg-Landau equation. By
+analytically evaluating the higher-order terms of the Floquet-Magnus expansion,
+we find that it is, at least asymptotically, convergent and well approximates
+the relaxation to their prethermal or non-equilibrium steady states. To support
+these analytical findings, we numerically analyze two examples: (i) the Kapitza
+pendulum with friction and (ii) laser-driven magnets described by the
+stochastic Landau-Lifshitz-Gilbert equation. In both cases, the effective EOMs
+obtained from their Floquet-Magnus expansions correctly reproduce their exact
+time evolution for a long time up to their non-equilibrium steady states. In
+the example of driven magnets, we demonstrate the controlled generations of a
+macroscopic magnetization and a spin chirality by laser and discuss possible
+applications to spintronics.",1810.01103v2
+2018-10-02,Geodesic motion on the groups of diffeomorphisms with $H^1$ metric as geometric generalised Lagrangian mean theory,"Generalized Lagrangian mean theories are used to analyze the interactions
+between mean flows and fluctuations, where the decomposition is based on a
+Lagrangian description of the flow. A systematic geometric framework was
+recently developed by Gilbert and Vanneste (J. Fluid Mech., 2018) who cast the
+decomposition in terms of intrinsic operations on the group of volume
+preserving diffeomorphism or on the full diffeomorphism group. In this setting,
+the mean of an ensemble of maps can be defined as the Riemannian center of mass
+on either of these groups. We apply this decomposition in the context of
+Lagrangian averaging where equations of motion for the mean flow arise via a
+variational principle from a mean Lagrangian, obtained from the kinetic energy
+Lagrangian of ideal fluid flow via a small amplitude expansion for the
+fluctuations.
+  We show that the Euler-$\alpha$ equations arise as Lagrangian averaged Euler
+equations when using the $L^2$-geodesic mean on the volume preserving
+diffeomorphism group of a manifold without boundaries, imposing a `Taylor
+hypothesis', which states that first order fluctuations are transported as a
+vector field by the mean flow, and assuming that fluctuations are statistically
+isotropic. Similarly, the EPDiff equations arise as the Lagrangian averaged
+Burgers' equations using the same argument on the full diffeomorphism group.
+These results generalize an earlier observation by Oliver (Proc. R. Soc. A,
+2017) to manifolds in geometrically fully intrinsic terms.",1810.01377v1
+2018-10-07,Training Convolutional Neural Networks and Compressed Sensing End-to-End for Microscopy Cell Detection,"Automated cell detection and localization from microscopy images are
+significant tasks in biomedical research and clinical practice. In this paper,
+we design a new cell detection and localization algorithm that combines deep
+convolutional neural network (CNN) and compressed sensing (CS) or sparse coding
+(SC) for end-to-end training. We also derive, for the first time, a
+backpropagation rule, which is applicable to train any algorithm that
+implements a sparse code recovery layer. The key observation behind our
+algorithm is that cell detection task is a point object detection task in
+computer vision, where the cell centers (i.e., point objects) occupy only a
+tiny fraction of the total number of pixels in an image. Thus, we can apply
+compressed sensing (or, equivalently sparse coding) to compactly represent a
+variable number of cells in a projected space. Then, CNN regresses this
+compressed vector from the input microscopy image. Thanks to the SC/CS recovery
+algorithm (L1 optimization) that can recover sparse cell locations from the
+output of CNN. We train this entire processing pipeline end-to-end and
+demonstrate that end-to-end training provides accuracy improvements over a
+training paradigm that treats CNN and CS-recovery layers separately. Our
+algorithm design also takes into account a form of ensemble average of trained
+models naturally to further boost accuracy of cell detection. We have validated
+our algorithm on benchmark datasets and achieved excellent performances.",1810.03075v1
+2018-11-16,Asymmetric Drift in the Andromeda Galaxy (M31) as a Function of Stellar Age,"We analyze the kinematics of Andromeda's disk as a function of stellar age by
+using photometry from the Panchromatic Hubble Andromeda Treasury (PHAT) survey
+and spectroscopy from the Spectroscopic and Photometric Landscape of
+Andromeda's Stellar Halo (SPLASH) survey. We use HI 21-cm and CO ($\rm J=1
+\rightarrow 0$) data to examine the difference between the deprojected rotation
+velocity of the gas and that of the stars. We divide the stars into four
+stellar age bins, from shortest lived to longest lived: massive main sequence
+stars (0.03 Gyr), more luminous intermediate mass asymptotic giant branch (AGB)
+stars (0.4 Gyr), less luminous intermediate mass AGB stars (2 Gyr), and low
+mass red giant branch stars (4 Gyr). There is a clear correlation between the
+offset of the stellar and the gas rotation velocity, or the asymmetric drift:
+the longer lived populations lag farther behind the gas than short lived
+populations. We also examine possible causes of the substructure in the
+rotation curves and find that the most significant cause of scatter in the
+rotation curves comes from the tilted ring model being an imperfect way to
+account for the multiple warps in Andromeda's disk.",1811.07037v2
+2018-11-21,"Exploring interfacial exchange coupling and sublattice effect in heavy metal/ferrimagnetic insulator heterostructures using Hall measurements, x-ray magnetic circular dichroism, and neutron reflectometry","We use temperature-dependent Hall measurements to identify contributions of
+spin Hall, magnetic proximity, and sublattice effects to the anomalous Hall
+signal in heavy metal/ferrimagnetic insulator heterostructures with
+perpendicular magnetic anisotropy. This approach enables detection of both the
+magnetic proximity effect onset temperature and the magnetization compensation
+temperature and provides essential information regarding the interfacial
+exchange coupling. Onset of a magnetic proximity effect yields a local extremum
+in the temperature-dependent anomalous Hall signal, which occurs at higher
+temperature as magnetic insulator thickness increases. This magnetic proximity
+effect onset occurs at much higher temperature in Pt than W. The magnetization
+compensation point is identified by a sharp anomalous Hall sign change and
+divergent coercive field. We directly probe the magnetic proximity effect using
+x-ray magnetic circular dichroism and polarized neutron reflectometry, which
+reveal an antiferromagnetic coupling between W and the magnetic insulator.
+Finally, we summarize the exchange-coupling configurations and the anomalous
+Hall-effect sign of the magnetized heavy metal in various heavy metal/magnetic
+insulator heterostructures.",1811.08574v2
+2018-12-13,Qatar Exoplanet Survey: Qatar-7b -- A Very Hot Jupiter Orbiting a Metal Rich F-Star,"We present the discovery of Qatar-7b --- a very hot and inflated giant gas
+planet orbiting close its parent star. The host star is a relatively massive
+main sequence F-star with mass and radius Mstar = 1.41 +/- 0.03 Msun and Rstar
+= 1.56 +/- 0.02 Rsun, respectively, at a distance d = 726 +/- 26 pc, and an
+estimated age ~1 Gyr. With its orbital period of P = 2.032 days the planet is
+located less than 5 stellar radii from its host star and is heated to a high
+temperature Teq ~ 2100 K. From a global solution to the available photometric
+and radial velocity observations, we calculate the mass and radius of the
+planet to be Mpl = 1.88 +/- 0.25 Mjup and Rpl = 1.70 +/- 0.03 Rjup,
+respectively. The planet radius and equilibrium temperature put Qatar-7b in the
+top 6% of the hottest and largest known exoplanets. With its large radius and
+high temperature Qatar-7b is a valuable addition to the short list of targets
+that offer the best opportunity for studying their atmospheres through
+transmission spectroscopy.",1812.05601v1
+2019-01-02,Leader Election in Well-Connected Graphs,"In this paper, we look at the problem of randomized leader election in
+synchronous distributed networks with a special focus on the message
+complexity. We provide an algorithm that solves the implicit version of leader
+election (where non-leader nodes need not be aware of the identity of the
+leader) in any general network with $O(\sqrt{n} \log^{7/2} n \cdot t_{mix})$
+messages and in $O(t_{mix}\log^2 n)$ time, where $n$ is the number of nodes and
+$t_{mix}$ refers to the mixing time of a random walk in the network graph $G$.
+For several classes of well-connected networks (that have a large conductance
+or alternatively small mixing times e.g. expanders, hypercubes, etc), the above
+result implies extremely efficient (sublinear running time and messages) leader
+election algorithms. Correspondingly, we show that any substantial improvement
+is not possible over our algorithm, by presenting an almost matching lower
+bound for randomized leader election. We show that
+$\Omega(\sqrt{n}/\phi^{3/4})$ messages are needed for any leader election
+algorithm that succeeds with probability at least $1-o(1)$, where $\phi$ refers
+to the conductance of a graph. To the best of our knowledge, this is the first
+work that shows a dependence between the time and message complexity to solve
+leader election and the connectivity of the graph $G$, which is often
+characterized by the graph's conductance $\phi$. Apart from the $\Omega(m)$
+bound in [Kutten et al., J.ACM 2015] (where $m$ denotes the number of edges of
+the graph), this work also provides one of the first non-trivial lower bounds
+for leader election in general networks.",1901.00342v1
+2019-01-23,Cooperation Speeds Surfing: Use Co-Bandit!,"In this paper, we explore the benefit of cooperation in adversarial bandit
+settings. As a motivating example, we consider the problem of wireless network
+selection. Mobile devices are often required to choose the right network to
+associate with for optimal performance, which is non-trivial. The excellent
+theoretical properties of EXP3, a leading multi-armed bandit algorithm, suggest
+that it should work well for this type of problem. Yet, it performs poorly in
+practice. A major limitation is its slow rate of stabilization. Bandit-style
+algorithms perform better when global knowledge is available, i.e., when
+devices receive feedback about all networks after each selection. But,
+unfortunately, communicating full information to all devices is expensive.
+Therefore, we address the question of how much information is adequate to
+achieve better performance. We propose Co-Bandit, a novel cooperative bandit
+approach, that allows devices to occasionally share their observations and
+forward feedback received from neighbors; hence, feedback may be received with
+a delay. Devices perform network selection based on their own observation and
+feedback from neighbors. As such, they speed up each other's rate of learning.
+We prove that Co-Bandit is regret-minimizing and retains the convergence
+property of multiplicative weight update algorithms with full information.
+Through simulation, we show that a very small amount of information, even with
+a delay, is adequate to nudge each other to select the right network and yield
+significantly faster stabilization at the optimal state (about 630x faster than
+EXP3).",1901.07768v1
+2019-01-31,Still out there: Modeling and Identifying Russian Troll Accounts on Twitter,"There is evidence that Russia's Internet Research Agency attempted to
+interfere with the 2016 U.S. election by running fake accounts on Twitter -
+often referred to as ""Russian trolls"". In this work, we: 1) develop machine
+learning models that predict whether a Twitter account is a Russian troll
+within a set of 170K control accounts; and, 2) demonstrate that it is possible
+to use this model to find active accounts on Twitter still likely acting on
+behalf of the Russian state. Using both behavioral and linguistic features, we
+show that it is possible to distinguish between a troll and a non-troll with a
+precision of 78.5% and an AUC of 98.9%, under cross-validation. Applying the
+model to out-of-sample accounts still active today, we find that up to 2.6% of
+top journalists' mentions are occupied by Russian trolls. These findings imply
+that the Russian trolls are very likely still active today. Additional analysis
+shows that they are not merely software-controlled bots, and manage their
+online identities in various complex ways. Finally, we argue that if it is
+possible to discover these accounts using externally - accessible data, then
+the platforms - with access to a variety of private internal signals - should
+succeed at similar or better rates.",1901.11162v1
+2019-02-11,Efficient Randomized Test-And-Set Implementations,"We study randomized test-and-set (TAS) implementations from registers in the
+asynchronous shared memory model with n processes. We introduce the problem of
+group election, a natural variant of leader election, and propose a framework
+for the implementation of TAS objects from group election objects. We then
+present two group election algorithms, each yielding an efficient TAS
+implementation. The first implementation has expected max-step complexity
+$O(\log^\ast k)$ in the location-oblivious adversary model, and the second has
+expected max-step complexity $O(\log\log k)$ against any read/write-oblivious
+adversary, where $k\leq n$ is the contention. These algorithms improve the
+previous upper bound by Alistarh and Aspnes [2] of $O(\log\log n)$ expected
+max-step complexity in the oblivious adversary model. We also propose a
+modification to a TAS algorithm by Alistarh, Attiya, Gilbert, Giurgiu, and
+Guerraoui [5] for the strong adaptive adversary, which improves its space
+complexity from super-linear to linear, while maintaining its $O(\log n)$
+expected max-step complexity. We then describe how this algorithm can be
+combined with any randomized TAS algorithm that has expected max-step
+complexity $T(n)$ in a weaker adversary model, so that the resulting algorithm
+has $O(\log n)$ expected max-step complexity against any strong adaptive
+adversary and $O(T(n))$ in the weaker adversary model. Finally, we prove that
+for any randomized 2-process TAS algorithm, there exists a schedule determined
+by an oblivious adversary such that with probability at least $(1/4)^t$ one of
+the processes needs at least t steps to finish its TAS operation. This
+complements a lower bound by Attiya and Censor-Hillel [7] on a similar problem
+for $n\geq 3$ processes.",1902.04002v1
+2019-03-11,Evidence for the formation of nanoprecipitates with magnetically disordered regions in bulk $\mathrm{Ni}_{50}\mathrm{Mn}_{45}\mathrm{In}_{5}$ Heusler alloys,"Shell ferromagnetism is a new functional property of certain Heusler alloys
+which has been recently observed in
+$\mathrm{Ni}_{50}\mathrm{Mn}_{45}\mathrm{In}_{5}$. We report the results of a
+comparative study of the magnetic microstructure of bulk
+$\mathrm{Ni}_{50}\mathrm{Mn}_{45}\mathrm{In}_{5}$ Heusler alloys using
+magnetometry, synchrotron x-ray diffraction, and magnetic small-angle neutron
+scattering (SANS). By combining unpolarized and spin-polarized SANS (POLARIS)
+we demonstrate that a number of important conclusions regarding the mesoscopic
+spin structure can be made. In particular, the analysis of the magnetic neutron
+data suggests that nanoprecipitates with an effective ferromagnetic component
+form in an antiferromagnetic matrix on field annealing at $700 \, \mathrm{K}$.
+These particles represent sources of perturbation, which seem to give rise to
+magnetically disordered regions in the vicinity of the particle-matrix
+interface. Analysis of the spin-flip SANS cross section via the computation of
+the correlation function yields a value of $\sim 55 \, \mathrm{nm}$ for the
+particle size and $\sim 20 \, \mathrm{nm}$ for the size of the spin-canted
+region.",1903.04183v1
+2019-03-14,"Low Field-size, Rate-Optimal Streaming Codes for Channels With Burst and Random Erasures","In this paper, we design erasure-correcting codes for channels with burst and
+random erasures, when a strict decoding delay constraint is in place. We
+consider the sliding-window-based packet erasure model proposed by Badr et al.,
+where any time-window of width $w$ contains either up to $a$ random erasures or
+an erasure burst of length at most $b$. One needs to recover any erased packet,
+where erasures are as per the channel model, with a strict decoding delay
+deadline of $\tau$ time slots. Presently existing rate-optimal constructions in
+the literature require, in general, a field-size which grows exponential in
+$\tau$, for a constant $\frac{a}{\tau}$. In this work, we present a new
+rate-optimal code construction covering all channel and delay parameters, which
+requires an $O(\tau^2)$ field-size. As a special case, when $(b-a)=1$, we have
+a field-size linear in $\tau$. We also present three other constructions having
+linear field-size, under certain constraints on channel and decoding delay
+parameters. As a corollary, we obtain low field-size, rate-optimal
+convolutional codes for any given column distance and column span. Simulations
+indicate that the newly proposed streaming code constructions offer lower
+packet-loss probabilities compared to existing schemes, for selected instances
+of Gilbert-Elliott and Fritchman channels.",1903.06210v1
+2019-03-21,Emergent topology and symmetry-breaking order in correlated quench dynamics,"Quenching a quantum system involves three basic ingredients: the initial
+phase, the post-quench target phase, and the non-equilibrium dynamics which
+carries the information of the former two. Here we propose a dynamical theory
+to characterize both the topology and symmetry-breaking order in correlated
+quantum system, through quenching the Haldane-Hubbard model from an initial
+magnetic phase to topologically nontrivial regime. The equation of motion for
+the complex pseudospin dynamics is obtained with the flow equation method, with
+the pseudospin evolution shown to obey a microscopic
+Landau-Lifshitz-Gilbert-Bloch equation. We find that the correlated quench
+dynamics exhibit robust universal behaviors on the so-called band-inversion
+surfaces (BISs), from which the nontrivial topology and magnetic order can be
+extracted. In particular, the topology of the post-quench regime can be
+characterized by an emergent dynamical topological pattern of quench dynamics
+on BISs, which is robust against dephasing and heating induced by interactions;
+the pre-quench symmetry-breaking orders is read out from a universal scaling
+behavior of the quench dynamics emerging on the BIS, which is valid beyond the
+mean-field regime. This work opens a way to characterize both the topology and
+symmetry-breaking orders by correlated quench dynamics.",1903.09144v3
+2019-03-22,Advanced Non-Destructive in Situ Characterization of Metals with the French Collaborating Research Group D2AM/BM02 Beamline at the European Synchrotron Radiation Facility,"The ability to non-destructively measure the structural properties of
+devices, either in situ or operando, are now possible using an intense X-ray
+synchrotron source combined with specialized equipment. This tool attracted
+researchers, in particular metallurgists, to attempt more complex and ambitious
+experiments aimed at answering unresolved questions in formation mechanisms,
+phase transitions, and magnetism complex alloys for industrial applications. In
+this paper, we introduce the diffraction diffusion anomale multi-longueur
+d'onde (D2AM) beamline, a French collaborating research group (CRG) beamline at
+the European Synchrotron Radiation Facility (ESRF), partially dedicated to in
+situ X-ray scattering experiments. The design of the beamline combined with the
+available equipment (two-dimensional fast photon counting detectors,
+sophisticated high precision kappa diffractometer, a variety of sample
+environments, continuous scanning for X-ray imaging, and specific software for
+data analysis) has made the D2AM beamline a highly efficient tool for advanced,
+in situ synchrotron characterization in materials science, e.g., single crystal
+or polycrystalline materials, powders, liquids, thin films, or epitaxial
+nanostructures. This paper gathers the main elements and equipment available at
+the beamline and shows its potential and flexibility in performing a wide
+variety of temporally, spatially, and energetically resolved X-ray synchrotron
+scattering measurements in situ.",1903.09390v1
+2019-03-31,Relaxation to equilibrium in models of classical spins with long-range interactions,"For a model long-range interacting system of classical Heisenberg spins, we
+study how fluctuations, such as those arising from having a finite system size
+or through interaction with the environment, affect the dynamical process of
+relaxation to Boltzmann-Gibbs equilibrium. Under deterministic spin
+precessional dynamics, we unveil the full range of quasistationary behavior
+observed during relaxation to equilibrium, whereby the system is trapped in
+nonequilibrium states for times that diverge with the system size. The
+corresponding stochastic dynamics, modeling interaction with the environment
+and constructed in the spirit of the stochastic Landau-Lifshitz-Gilbert
+equation, however shows a fast relaxation to equilibrium on a size-independent
+timescale and no signature of quasistationarity, provided the noise is strong
+enough. Similar fast relaxation is also seen in Glauber Monte Carlo dynamics of
+the model, thus establishing the ubiquity of what has been reported earlier in
+particle dynamics (hence distinct from the spin dynamics considered here) of
+long-range interacting systems, that quasistationarity observed in
+deterministic dynamics is washed away by fluctuations induced through contact
+with the environment.",1904.00432v2
+2019-04-27,Blue-Light-Emitting Color Centers in High-Quality Hexagonal Boron Nitride,"Light emitters in wide band gap semiconductors are of great fundamental
+interest and have potential as optically addressable qubits. Here we describe
+the discovery of a new color center in high-quality hexagonal boron nitride
+(h-BN) with a sharp emission line at 435 nm. The emitters are activated and
+deactivated by electron beam irradiation and have spectral and temporal
+characteristics consistent with atomic color centers weakly coupled to lattice
+vibrations. The emitters are conspicuously absent from commercially available
+h-BN and are only present in ultra-high-quality h-BN grown using a
+high-pressure, high-temperature Ba-B-N flux/solvent, suggesting that these
+emitters originate from impurities or related defects specific to this unique
+synthetic route. Our results imply that the light emission is activated and
+deactivated by electron beam manipulation of the charge state of an
+impurity-defect complex.",1904.12107v6
+2019-04-30,Realization of Ordered Magnetic Skyrmions in Thin Films at Ambient Conditions,"Magnetic skyrmions present interesting physics due to their topological
+nature and hold significant promise for future information technologies. A key
+barrier to realizing skyrmion devices has been stabilizing these spin
+structures under ambient conditions. In this manuscript, we exploit the tunable
+magnetic properties of amorphous Fe/Gd mulitlayers to realize skyrmion lattices
+which are stable over a large temperature and magnetic field parameter space,
+including room temperature and zero magnetic field. These hybrid skyrmions have
+both Bloch-type and N\'eel-type character and are stabilized by dipolar
+interactions rather than Dzyaloshinskii-Moriya interactions, which are
+typically considered required for the generation of skyrmions. Small angle
+neutron scattering (SANS) was used in combination with soft X-ray microscopy to
+provide a unique, multi-scale probe of the local and long-range order of these
+structures. These results identify a pathway to engineer controllable skyrmion
+phases in thin film geometries which are stable at ambient conditions.",1904.13274v1
+2019-05-16,Ultralow-loss domain wall motion driven by magnetocrystalline anisotropy gradient in antiferromagnetic nanowire,"Searching for new methods controlling antiferromagnetic (AFM) domain wall is
+one of the most important issues for AFM spintronic device operation. In this
+work, we study theoretically the domain wall motion of an AFM nanowire, driven
+by the axial anisotropy gradient generated by external electric field, allowing
+the electro control of AFM domain wall motion in the merit of ultra-low energy
+loss. The domain wall velocity depending on the anisotropy gradient magnitude
+and intrinsic material properties is simulated based on the
+Landau-Lifshitz-Gilbert equation and also deduced using the energy dissipation
+theorem. It is found that the domain wall moves at a nearly constant velocity
+for small gradient, and accelerates for large gradient due to the enlarged
+domain wall width. The domain wall mobility is independent of lattice dimension
+and types of domain wall, while it is enhanced by the Dzyaloshinskii-Moriya
+interaction. In addition, the physical mechanism for much faster AFM wall
+dynamics than ferromagnetic wall dynamics is qualitatively explained. This work
+unveils a promising strategy for controlling the AFM domain walls, benefiting
+to future AFM spintronic applications.",1905.06695v2
+2019-05-22,Constraining level densities using spectral data,"Several models of level densities exist and they often make simplified
+assumptions regarding the overall behavior of the total level densities (LD)
+and the intrinsic spin and parity distributions of the excited states.
+Normally, such LD models are constrained only by the measured $D_0$, i.e. the
+density of levels at the neutron separation energy of the compound nucleus
+(target plus neutron), and the sometimes subjective extrapolation of discrete
+levels. In this work we use microscopic Hartree-Fock-Bogoliubov (HFB) level
+densities, which intrinsically provide more realistic spin and parity
+distributions, and associate variations predicted by the HFB model with the
+observed double-differential cross sections at low outgoing neutron energy,
+region that is dominated by the LD input. With this approach we are able to
+perform fits of the LD based on actual experimental data, constraining the
+model and ensuring its consistency. This approach can be particularly useful in
+extrapolating the LD to nuclei for which high-excited discrete levels and/or
+values of $D_0$ are unknown. It also predicts inelastic gamma
+(n,n$^{\prime}\gamma$) cross sections that in some cases can differ
+significantly from more standard LD models such as Gilbert-Cameron.",1905.09194v1
+2019-05-23,The Kepler Smear Campaign: Light curves for 102 Very Bright Stars,"We present the first data release of the Kepler Smear Campaign, using
+collateral 'smear' data obtained in the Kepler four-year mission to reconstruct
+light curves of 102 stars too bright to have been otherwise targeted. We
+describe the pipeline developed to extract and calibrate these light curves,
+and show that we attain photometric precision comparable to stars analyzed by
+the standard pipeline in the nominal Kepler mission. In this paper, aside from
+publishing the light curves of these stars, we focus on 66 red giants for which
+we detect solar-like oscillations, characterizing 33 of these in detail with
+spectroscopic chemical abundances and asteroseismic masses as benchmark stars.
+We also classify the whole sample, finding nearly all to be variable, with
+classical pulsations and binary effects. All source code, light curves, TRES
+spectra, and asteroseismic and stellar parameters are publicly available as a
+Kepler legacy sample.",1905.09831v1
+2019-06-06,A Hot Saturn Near (but unassociated with) the Open Cluster NGC 1817,"We report on the discovery of a hot Saturn-sized planet (9.916 +/- 0.985
+R_earth) around a late F star, EPIC 246865365, observed in Campaign 13 of the
+K2 mission. We began studying this planet candidate because prior to the
+release of Gaia DR2, the host star was thought to have been a member (> 90%
+membership probability) of the approximately 1 Gyr open cluster NGC 1817 based
+on its kinematics and photometric distance. We identify the host star (among
+three stars within the K2 photometric aperture) using seeing-limited photometry
+and rule out false positive scenarios using adaptive optics imaging and radial
+velocity observations. We statistically validate EPIC 246865365b by calculating
+a false positive probability rate of 0.01%. However, we also show using new
+kinematic measurements provided by Gaia DR2 and our measured radial velocity of
+the system that EPIC 246865365 is unassociated with the cluster NGC 1817.
+Therefore, the long-running search for a giant transiting planet in an open
+cluster remains fruitless. Finally, we note that our use of seeing-limited
+photometry is a good demonstration of similar techniques that are already being
+used to follow up TESS planet candidates, especially in crowded regions.",1906.02395v1
+2019-06-12,Towards the nucleon hadronic tensor from lattice QCD,"We present the first calculation of the hadronic tensor on the lattice for
+the nucleon. The hadronic tensor can be used to extract the structure functions
+in deep inelastic scatterings and also provide information for the
+neutrino-nucleon scattering which is crucial to the neutrino-nucleus scattering
+experiments at low energies. The most challenging part in the calculation is to
+solve an inverse problem. We have implemented and tested three algorithms using
+mock data, showing that the Bayesian Reconstruction method has the best
+resolution in extracting peak structures while the Backus-Gilbert and Maximum
+Entropy methods are somewhat more stable for the flat spectral function.
+Numerical results are presented for both the elastic case (clover fermions on
+domain wall configuration with $m_\pi\sim$ 370 MeV and $a\sim$ 0.06 fm) and a
+case (anisotropic clover lattice with $m_\pi\sim$ 380 MeV and $a_t\sim$ 0.035
+fm) with large momentum transfer. For the former case, the reconstructed
+Minkowski hadronic tensor gives precisely the vector charge which proves the
+feasibility of the approach. While for the latter case, the nucleon resonances
+and possibly shallow inelastic scattering contributions around $\nu=1$ GeV are
+clearly observed but no information is obtained for higher excited states with
+$\nu>2$ GeV. A check of the effective masses of $\rho$ meson with different
+lattice setups indicates that, in order to reach higher energy transfers, using
+lattices with smaller lattice spacings is essential.",1906.05312v1
+2019-06-17,Non-equilibrium Green's Function and First Principle Approach to Modeling of Multiferroic Tunnel Junctions,"Recently, multiferroic tunnel junctions (MFTJs) have gained significant
+spotlight in the literature due to its high tunneling electro-resistance
+together with its non-volatility. In order to analyze such devices and to have
+insightful understanding of its characteristics, there is a need for developing
+a multi-physics modeling and simulation framework. The simulation framework
+discussed in this paper is motivated by the scarcity of such multi-physics
+studies in the literature. In this study, a theoretical analysis of MFTJs is
+demonstrated using self-consistent analysis of spin-based non-equilibrium
+Green's function (NEGF) method to estimate the tunneling current,
+Landau-Khalatnikov (LK) equation to model the ferroelectric polarization
+dynamics, together with landau-Lifshitz-Gilbert's (LLG) equations to capture
+the magnetization dynamics. The spin-based NEGF method is equipped with a
+magnetization dependent Hamiltonian that eases the modeling of the tunneling
+electro-resistance (TER), tunneling magneto-resistance (TMR), and the
+magnetoelectric effect (ME) in MFTJs. Moreover, we apply the first principle
+calculations to estimate the screening lengths of the MFTJ electrodes that are
+necessary for estimation of tunneling current. The simulation results of the
+proposed framework are in good agreement with the experimental results.
+Finally, a comprehensive analysis of TER and TMR of MFTJs and their dependence
+on various device parameters is illustrated.",1906.06986v1
+2019-06-27,Indications for Dzyaloshinskii-Moriya Interaction at the Pd/Fe Interface Studied by \textit{In Situ} Polarized Neutron Reflectometry,"Using \textit{in situ} polarized neutron reflectometry, the depth resolved
+evolution of the magnetism and structure in a Pd/Fe/Pd trilayer thin-film is
+measured during growth. The initial film structure of Pd/Fe shows a small
+proximity induced magnetism in the underlayer and a magnetization in the Fe
+layer of $\approx1.6$\,$\mu_{\text{B}}$ per Fe atom, less than the expected
+bulk value of $2.2$\,$\mu_{\text{B}}$. Deposition of the Pd capping layer
+initially follows an island-like growth mode with subsequent coalescence. With
+increasing Pd deposition the Fe moment and the proximity-induced magnetism in
+the Pd capping layer decrease. After final deposition of the Pd capping layer,
+the magnetic profile is structurally and magnetically symmetric across the Fe
+layer, with magnetism induced in Pd up to 0.92 \,nm from the interface.
+Throughout the Pd deposition the Pd/Fe/Pd trilayer structure is becoming
+increasingly symmetric, a fact which points to a Dzyaloshinskii-Moriya
+interaction as a likely cause of the observed magnetic behavior.",1906.11532v1
+2019-07-01,Robust Formation of Ultrasmall Room-Temperature Neél Skyrmions in Amorphous Ferrimagnets from Atomistic Simulations,"Ne\'el skyrmions originate from interfacial Dzyaloshinskii Moriya interaction
+(DMI). Recent studies have explored using thin-film ferromagnets and
+ferrimagnets to host Ne\'el skyrmions for spintronic applications. However, it
+is unclear if ultrasmall (10 nm or less) skyrmions can ever be stabilized at
+room temperature for practical use in high density parallel racetrack memories.
+While thicker films can improve stability, DMI decays rapidly away from the
+interface. As such, spins far away from the interface would experience
+near-zero DMI, raising question on whether or not unrealistically large DMI is
+needed to stabilize skyrmions, and whether skyrmions will also collapse away
+from the interface. To address these questions, we have employed atomistic
+stochastic Landau-Lifshitz-Gilbert simulations to investigate skyrmions in
+amorphous ferrimagnetic GdCo. It is revealed that a significant reduction in
+DMI below that of Pt is sufficient to stabilize ultrasmall skyrmions even in
+films as thick as 15 nm. Moreover, skyrmions are found to retain a uniform
+columnar shape across the film thickness despite the decaying DMI. Our results
+show that increasing thickness and reducing DMI in GdCo can further reduce the
+size of skyrmions at room temperature, which is crucial to improve the density
+and energy efficiency in skyrmion based devices.",1907.00647v1
+2019-07-03,Effect of Zeeman coupling on the Majorana vortex modes in iron-based topological superconductors,"In the superconducting regime of FeTe$_{(1-x)}$Se$_x$, there exist two types
+of vortices which are distinct by the presence or absence of zero energy states
+in their core. To understand their origin, we examine the interplay of Zeeman
+coupling and superconducting pairings in three-dimensional metals with band
+inversion. Weak Zeeman fields are found to suppress the intra-orbital
+spin-singlet pairing, known to localize the states at the ends of the vortices
+on the surface. On the other hand, an orbital-triplet pairing is shown to be
+stable against Zeeman interactions, but leads to delocalized zero-energy
+Majorana modes which extend through the vortex. In contrast, the finite-energy
+vortex modes remain localized at the vortex ends even when the pairing is of
+orbital-triplet form. Phenomenologically, this manifests as an observed
+disappearance of zero-bias peaks within the cores of topological vortices upon
+increase of the applied magnetic field. The presence of magnetic impurities in
+FeTe$_{(1-x)}$Se$_x$, which are attracted to the vortices, would lead to such
+Zeeman-induced delocalization of Majorana modes in a fraction of vortices that
+capture a large enough number of magnetic impurities. Our results provide an
+explanation to the dichotomy between topological and non-topological vortices
+recently observed in FeTe$_{(1-x)}$Se$_x$.",1907.02077v2
+2019-07-10,Increasing Gender Diversity and Inclusion in Scientific Committees and Related Activities at STScI,"We present a new initiative by the Women in Astronomy Forum at Space
+Telescope Science Institute (STScI) to increase gender diversity and inclusion
+in STScI's scientific committees and the activities they generate. This
+initiative offers new and uniform guidelines on binary gender representation
+goals for each committee and recommendations on how to achieve them in a
+homogeneous way, as well as metrics and tools to track progress towards defined
+goals. While the new guidelines presented in the paper focus on binary gender
+representation, they can be adapted and implemented to support all minority
+groups. By creating diverse committees and making them aware of, and trained on
+implicit bias, we expect to create a diverse outcome in the activities they
+generate, which, in turn, will advance science further and faster.",1907.04880v1
+2019-07-19,Sparse Recovery for Orthogonal Polynomial Transforms,"In this paper we consider the following sparse recovery problem. We have
+query access to a vector $\vx \in \R^N$ such that $\vhx = \vF \vx$ is
+$k$-sparse (or nearly $k$-sparse) for some orthogonal transform $\vF$. The goal
+is to output an approximation (in an $\ell_2$ sense) to $\vhx$ in sublinear
+time. This problem has been well-studied in the special case that $\vF$ is the
+Discrete Fourier Transform (DFT), and a long line of work has resulted in
+sparse Fast Fourier Transforms that run in time $O(k \cdot \mathrm{polylog}
+N)$. However, for transforms $\vF$ other than the DFT (or closely related
+transforms like the Discrete Cosine Transform), the question is much less
+settled.
+  In this paper we give sublinear-time algorithms---running in time $\poly(k
+\log(N))$---for solving the sparse recovery problem for orthogonal transforms
+$\vF$ that arise from orthogonal polynomials. More precisely, our algorithm
+works for any $\vF$ that is an orthogonal polynomial transform derived from
+Jacobi polynomials. The Jacobi polynomials are a large class of classical
+orthogonal polynomials (and include Chebyshev and Legendre polynomials as
+special cases), and show up extensively in applications like numerical analysis
+and signal processing. One caveat of our work is that we require an assumption
+on the sparsity structure of the sparse vector, although we note that vectors
+with random support have this property with high probability.
+  Our approach is to give a very general reduction from the $k$-sparse sparse
+recovery problem to the $1$-sparse sparse recovery problem that holds for any
+flat orthogonal polynomial transform; then we solve this one-sparse recovery
+problem for transforms derived from Jacobi polynomials.",1907.08362v1
+2019-08-28,Interplay of spin and mass superfluidity in antiferromagnetic spin-1 BEC and bicirculation vortices,"The paper investigates the coexistence and interplay of spin and mass
+superfluidity in the antiferromagnetic spin-1 BEC. The hydrodynamical theory
+describes the spin degree of freedom by the equations similar to the
+Landau--Lifshitz--Gilbert theory for bipartite antiferromagnetic insulator. The
+variables in the spin space are two subspins with absolute value $\hbar/2$,
+which play the role of two sublattice spins in the antiferromagnetic
+insulators. As well as in bipartite antiferromagnetic insulators, in the
+antiferromagnetic spin-1 BEC there are two spin-wave modes, one is a gapless
+Goldstone mode, another is gapped. The Landau criterion shows that in limit of
+small total spin (two subspins are nearly antiparallel) instability of
+supercurrents starts from the gapped mode. In the opposite limit of large total
+spin (two subspins are nearly parallel) the gapless modes become unstable
+earlier than the gapped one. Mass and spin supercurrents decay via phase slips,
+when vortices cross streamlines of supercurrent. The vortices participating in
+phase slips are nonsingular bicirculation vortices. They are characterized by
+two topological charges, which are winding numbers describing circulations of
+two angles around the vortex axis. The winding numbers can be half-integer. A
+particular example of a half-integer vortex is a half-quantum vortex with the
+superfluid velocity circulation $h/2m$. But the superfluid velocity circulation
+is not a topological charge, and in general the quantum of this circulation can
+be continuously tuned from 0 to $h/2m$.",1908.10633v2
+2019-09-23,"The NASA Probe space mission concept, Cosmic Evolution Through UV Surveys (CETUS)","The mission concept, Cosmic Origins Through UV Surveys (CETUS) is an all-UV
+space mission concept that was selected and funded by NASA for study in 2017.
+The main capabilities of CETUS that even Hubble doesn't have are: (1)
+wide-field (17.4'x17.4') imaging and spectroscopy of astronomical sources with
+<0.5'' resolution; (2) spectral sensitivity to UV radiation at wavelengths as
+short as 1000 {\AA}; (3) near-UV multi-object slit spectroscopy; and (4)
+rapid-response UV spectroscopy and deep imaging of transients like GW 170817;
+and (5) 23 times higher sensitivity to extended sources.
+  The main purposes of this CETUS Final Report are to describe the CETUS
+scientific program and to demonstrate the maturity of its instrumentation,
+which forms the basis of its estimated cost. While there are similarities of
+this Final Report to that submitted to NASA in March 2019 by the Goddard Space
+Flight Center, there are important differences including the following. *
+Science. The science case has been refreshed, deepened, and expanded as a
+result of ideas and recommendations expressed in the Astro2020 science white
+papers. * Instrumentation. Detailed investigations including a high-level error
+budget for focus with implications for thermal management, target acquisition
+in the MOS micro-shutter array, contamination control have been carried out. *
+Mission Design. The spacecraft and mission operations concepts as developed by
+NGIS Gilbert (formerly Orbital ATK) rather than the output of Goddard's Mission
+Design Lab have been adopted.. * Technology. Technology maturation plans have
+been updated.",1909.10437v1
+2019-09-25,"Towards an improved understanding of molecular evolution: the relative roles of selection, drift, and everything in between","A major goal of molecular evolutionary biology is to identify loci or regions
+of the genome under selection versus those evolving in a neutral manner.
+Correct identification allows accurate inference of the evolutionary process
+and thus comprehension of historical and contemporary processes driving
+phenotypic change and adaptation. A fundamental difficulty lies in
+distinguishing sites targeted by selection from both sites linked to these
+targets and sites fully independent of selection. These three categories of
+sites necessitate attention in light of the debate over the relative importance
+of selection versus neutrality and the neutral theory. Modern genomic insights
+have proved that complex processes such as linkage, demography, and biased gene
+conversion complicate our understanding of the role of neutral versus selective
+processes in evolution. In this perspective, we first highlight the importance
+of the genomic and (a)biotic context of new mutations to identify the targets
+of natural selection. We then present mechanisms that may constrain the
+evolution of genomes and bias the inference of selection. We discuss these
+mechanisms within the two critical levels that they occur: the population level
+and the molecular level. We highlight that they should be taken into account to
+correctly distinguish sites across the genome subject to selective or
+non-selective forces and stress that a major current field-wide goal is to
+quantify the absolute importance of these mechanisms.",1909.11490v4
+2019-10-08,Correlated fluctuations in spin orbit torque-coupled perpendicular nanomagnets,"Low barrier nanomagnets have attracted a lot of research interest for their
+use as sources of high quality true random number generation. More recently,
+low barrier nanomagnets with tunable output have been shown to be a natural
+hardware platform for unconventional computing paradigms such as probabilistic
+spin logic. Efficient generation and tunability of high quality random bits is
+critical for these novel applications. However, current spintronic random
+number generators are based on superparamagnetic tunnel junctions (SMTJs) with
+tunability obtained through spin transfer torque (STT), which unavoidably leads
+to challenges in designing concatenated networks using these two terminal
+devices. The more recent development of utilizing spin orbit torque (SOT)
+allows for a three terminal device design, but can only tune in-plane
+magnetization freely, which is not very energy efficient due to the needs of
+overcoming a large demagnetization field. In this work, we experimentally
+demonstrate for the first time, a stochastic device with perpendicular magnetic
+anisotropy (PMA) that is completely tunable by SOT without the aid of any
+external magnetic field. Our measurements lead us to hypothesize that a tilted
+anisotropy might be responsible for the observed tunability. We carry out
+stochastic Landau-Lifshitz-Gilbert (sLLG) simulations to confirm our
+experimental observation. Finally, we build an electrically coupled network of
+two such stochastic nanomagnet based devices and demonstrate that finite
+correlation or anti-correlation can be established between their output
+fluctuations by a weak interconnection, despite having a large difference in
+their natural fluctuation time scale. Simulations based on a newly developed
+dynamical model for autonomous circuits composed of low barrier nanomagnets
+show close agreement with the experimental results.",1910.03184v1
+2019-10-09,"Prophets, Secretaries, and Maximizing the Probability of Choosing the Best","Suppose a customer is faced with a sequence of fluctuating prices, such as
+for airfare or a product sold by a large online retailer. Given distributional
+information about what price they might face each day, how should they choose
+when to purchase in order to maximize the likelihood of getting the best price
+in retrospect? This is related to the classical secretary problem, but with
+values drawn from known distributions. In their pioneering work, Gilbert and
+Mosteller [\textit{J. Amer. Statist. Assoc. 1966}] showed that when the values
+are drawn i.i.d., there is a thresholding algorithm that selects the best value
+with probability approximately $0.5801$. However, the more general problem with
+non-identical distributions has remained unsolved.
+  In this paper we provide an algorithm for the case of non-identical
+distributions that selects the maximum element with probability $1/e$, and we
+show that this is tight. We further show that if the observations arrive in a
+random order, this barrier of $1/e$ can be broken using a static threshold
+algorithm, and we show that our success probability is the best possible for
+any single-threshold algorithm under random observation order. Moreover, we
+prove that one can achieve a strictly better success probability using more
+general multi-threshold algorithms, unlike the non-random-order case. Along the
+way, we show that the best achievable success probability for the random-order
+case matches that of the i.i.d.\ case, which is approximately $0.5801$, under a
+""no-superstars"" condition that no single distribution is very likely ex ante to
+generate the maximum value. We also extend our results to the problem of
+selecting one of the $k$ best values.",1910.03798v1
+2019-10-24,Order and Information in the Patterns of Spinning Magnetic Micro-disks at the Air-water Interface,"The application of the Shannon entropy to study the relationship between
+information and structures has yielded insights into molecular and material
+systems. However, the difficulty in directly observing and manipulating atoms
+and molecules hampers the ability of these systems to serve as model systems
+for further exploring the links between information and structures. Here, we
+use, as a model experimental system, hundreds of spinning magnetic micro-disks
+self-organizing at the air-water interface to generate various spatiotemporal
+patterns with varying degrees of orders. Using the neighbor distance as the
+information-bearing variable, we demonstrate the links among information,
+structure, and interactions. Most importantly, we establish a direct link
+between information and structure without using explicit knowledge of
+interactions. Finally, we show that the Shannon entropy by neighbor distances
+is a powerful observable in characterizing structural changes. Our findings are
+relevant for analyzing natural self-organizing systems and for designing
+collective robots.",1910.11226v3
+2019-11-17,Interfacial-Redox-Induced Tuning of Superconductivity in YBa$_{2}$Cu$_{3}$O$_{7-δ}$,"Solid state ionic approaches for modifying ion distributions in getter/oxide
+heterostructures offer exciting potentials to control material properties. Here
+we report a simple, scalable approach allowing for total control of the
+superconducting transition in optimally doped YBa$_{2}$Cu$_{3}$O$_{7-{\delta}}$
+(YBCO) films via a chemically-driven ionic migration mechanism. Using a thin Gd
+capping layer of up to 20 nm deposited onto 100 nm thick epitaxial YBCO films,
+oxygen is found to leach from deep within the YBCO. Progressive reduction of
+the superconducting transition is observed, with complete suppression possible
+for a sufficiently thick Gd layer. These effects arise from the combined impact
+of redox-driven electron doping and modification of the YBCO microstructure due
+to oxygen migration and depletion. This work demonstrates an effective ionic
+control of superconductivity in oxides, an interface induced effect that goes
+well into the quasi-bulk regime, opening up possibilities for electric field
+manipulation.",1911.07275v1
+2019-12-10,Integration of Neural Network-Based Symbolic Regression in Deep Learning for Scientific Discovery,"Symbolic regression is a powerful technique that can discover analytical
+equations that describe data, which can lead to explainable models and
+generalizability outside of the training data set. In contrast, neural networks
+have achieved amazing levels of accuracy on image recognition and natural
+language processing tasks, but are often seen as black-box models that are
+difficult to interpret and typically extrapolate poorly. Here we use a neural
+network-based architecture for symbolic regression called the Equation Learner
+(EQL) network and integrate it with other deep learning architectures such that
+the whole system can be trained end-to-end through backpropagation. To
+demonstrate the power of such systems, we study their performance on several
+substantially different tasks. First, we show that the neural network can
+perform symbolic regression and learn the form of several functions. Next, we
+present an MNIST arithmetic task where a separate part of the neural network
+extracts the digits. Finally, we demonstrate prediction of dynamical systems
+where an unknown parameter is extracted through an encoder. We find that the
+EQL-based architecture can extrapolate quite well outside of the training data
+set compared to a standard neural network-based architecture, paving the way
+for deep learning to be applied in scientific exploration and discovery.",1912.04825v2
+2019-12-17,New search for mirror neutron regeneration,"The possibility of relatively fast neutron oscillations into a mirror neutron
+state is not excluded experimentally when a mirror magnetic field is
+considered. Direct searches for the disappearance of neutrons into mirror
+neutrons in a controlled magnetic field have previously been performed using
+ultracold neutrons, with some anomalous results reported. We describe a
+technique using cold neutrons to perform a disappearance and regeneration
+search, which would allow us to unambiguously identify a possible oscillation
+signal. An experiment using the existing General Purpose-Small Angle Neutron
+Scattering instrument at the High Flux Isotope Reactor at Oak Ridge National
+Laboratory will have the sensitivity to fully explore the parameter space of
+prior ultracold neutron searches and confirm or refute previous claims of
+observation. This instrument can also conclusively test the validity of
+recently suggested oscillation-based explanations for the neutron lifetime
+anomaly.",1912.08264v1
+2020-01-06,Highly efficient spin orbit torque in Pt/Co/Ir multilayers with antiferromagnetic interlayer exchange coupling,"We have studied the spin orbit torque (SOT) in Pt/Co/Ir multilayers with 3
+repeats of the unit structure. As the system exhibits oscillatory interlayer
+exchange coupling (IEC) with varying Ir layer thickness, we compare the SOT of
+films when the Co layers are coupled ferromagnetically and
+antiferromagnetically. SOT is evaluated using current induced shift of the
+anomalous Hall resistance hysteresis loops. A relatively thick Pt layer,
+serving as a seed layer to the multilayer, is used to generate spin current via
+the spin Hall effect. In the absence of antiferromagnetic coupling, the SOT is
+constant against the applied current density and the corresponding spin torque
+efficiency (i.e. the effective spin Hall angle) is $\sim$0.09, in agreement
+with previous reports. In contrast, for films with antiferromagnetic coupling,
+the SOT increases with the applied current density and eventually saturates.
+The SOT at saturation is a factor of $\sim$15 larger than that without the
+antiferromagnetic coupling. The spin torque efficiency is $\sim$5 times larger
+if we assume the net total magnetization is reduced by a factor of 3 due to the
+antiferromagnetic coupling. Model calculations based on the Landau Lifshitz
+Gilbert equation show that the presence of antiferromagnetic coupling can
+increase the SOT but the degree of enhancement is limited, in this case, to a
+factor of 1.2-1.4. We thus consider there are other sources of SOT, possibly at
+the interfaces, which may account for the highly efficient SOT in the
+uncompensated synthetic anti-ferromagnet (SAF) multilayers.",2001.01454v1
+2019-11-24,Cybernetical Concepts for Cellular Automaton and Artificial Neural Network Modelling and Implementation,"As a discipline cybernetics has a long and rich history. In its first
+generation it not only had a worldwide span, in the area of computer modelling,
+for example, its proponents such as John von Neumann, Stanislaw Ulam, Warren
+McCulloch and Walter Pitts, also came up with models and methods such as
+cellular automata and artificial neural networks, which are still the
+foundation of most modern modelling approaches. At the same time, cybernetics
+also got the attention of philosophers, such as the Frenchman Gilbert Simondon,
+who made use of cybernetical concepts in order to establish a metaphysics and a
+natural philosophy of individuation, giving cybernetics thereby a philosophical
+interpretation, which he baptised allagmatic. In this paper, we emphasise this
+allagmatic theory by showing how Simondon's philosophical concepts can be used
+to formulate a generic computer model or metamodel for complex systems
+modelling and its implementation in program code, according to generic
+programming. We also present how the developed allagmatic metamodel is capable
+of building simple cellular automata and artificial neural networks.",2001.02037v3
+2020-02-12,Competition between magnetic order and charge localization in Na$_2$IrO$_3$ thin crystal devices,"Spin orbit assisted Mott insulators such as sodium iridate (Na$_2$IrO$_3$)
+have been an important subject of study in the recent years. In these
+materials, the interplay of electronic correlations, spin-orbit coupling,
+crystal field effects and a honeycomb arrangement of ions bring exciting ground
+states, predicted in the frame of the Kitaev model. The insulating character of
+Na$_2$IrO$_3$ has hampered its integration to an electronic device, desirable
+for applications, such as the manipulation of quasiparticles interesting for
+topological quantum computing. Here we show through electronic transport
+measurements supported by Angle Resolved Photoemission Spectroscopy (ARPES)
+experiments, that electronic transport in Na$_2$IrO$_3$ is ruled by variable
+range hopping and it is strongly dependent on the magnetic ordering transition
+known for bulk Na$_2$IrO$_3$, as well as on external electric fields.
+Electronic transport measurements allow us to deduce a value for the
+localization length and the density of states in our Na$_2$IrO$_3$ thin
+crystals devices, offering an alternative approach to study insulating layered
+materials.",2002.04785v1
+2020-02-13,Electron Beam-Induced Nanopores in Bernal-Stacked Hexagonal Boron Nitride,"Controlling the size and shape of nanopores in two-dimensional materials is a
+key challenge in applications such as DNA sequencing, sieving, and quantum
+emission in artificial atoms. We here investigate experimentally and
+theoretically triangular vacancies in (unconventional) Bernal-stacked AB-h-BN
+formed using a high-energy electron beam. Due to the geometric configuration of
+AB-h-BN, triangular pores in different layers are aligned, and their sizes are
+controlled by the duration of the electron irradiation. Interlayer covalent
+bonding at the vacancy edge is not favored, as opposed to what occurs in the
+more common AA'-stacked BN. A variety of monolayer, concentric and bilayer
+pores in bilayer AB-h-BN are observed in high-resolution transmission electron
+microscopy and characterized using ab initio simulations. Bilayer pores in
+AB-h-BN are commonly formed, and grow without breaking the bilayer character.
+Nanopores in AB-h-BN exhibit a wide range of electronic properties, ranging
+from half-metallic to non-magnetic and magnetic semiconducting. Therefore,
+because of the controllability of the pore size, the electronic structure is
+also highly controllable in these systems, and can potentially be tuned for
+particular applications.",2002.05795v3
+2020-02-26,Effect of chemical substitution on the skyrmion phase in Cu$_2$OSeO$_3$,"Magnetic skyrmions have been the focus of intense research due to their
+unique qualities which result from their topological protections. Previous work
+on Cu$_2$OSeO$_3$, the only known insulating multiferroic skyrmion material,
+has shown that chemical substitution alters the skyrmion phase. We chemically
+substitute Zn, Ag, and S into powdered Cu$_2$OSeO$_3$ to study the effect on
+the magnetic phase diagram. In both the Ag and the S substitutions, we find
+that the skyrmion phase is stabilized over a larger temperature range, as
+determined via magnetometry and small-angle neutron scattering (SANS).
+Meanwhile, while previous magnetometry characterization suggests two high
+temperature skyrmion phases in the Zn-substituted sample, SANS reveals the high
+temperature phase to be skyrmionic while we are unable to distinguish the other
+from helical order. Overall, chemical substitution weakens helical and skyrmion
+order as inferred from neutron scattering of the $|$q$| \approx$ 0.01
+$\r{A}^{-1}$ magnetic peak.",2002.11827v1
+2020-03-10,Smart City IoT Services Creation through Large Scale Collaboration,"Smart cities solutions are often monolithically implemented, from sensors
+data handling through to the provided services. The same challenges are
+regularly faced by different developers, for every new solution in a new city.
+Expertise and know-how can be re-used and the effort shared. In this article we
+present the methodologies to minimize the efforts of implementing new smart
+city solutions and maximizing the sharing of components. The final target is to
+have a live technical community of smart city application developers. The
+results of this activity comes from the implementation of 35 city services in
+27 cities between Europe and South Korea. To share efforts, we encourage
+developers to devise applications using a modular approach. Single-function
+components that are re-usable by other city services are packaged and published
+as standalone components, named Atomic Services. We identify 15 atomic services
+addressing smart city challenges in data analytics, data evaluation, data
+integration, data validation, and visualization. 38 instances of the atomic
+services are already operational in several smart city services. We detail in
+this article, as atomic service examples, some data predictor components.
+Furthermore, we describe real-world atomic services usage in the scenarios of
+Santander and three Danish cities. The resulting atomic services also generate
+a side market for smart city solutions, allowing expertise and know-how to be
+re-used by different stakeholders.",2003.04843v1
+2020-03-23,Low Power Unsupervised Anomaly Detection by Non-Parametric Modeling of Sensor Statistics,"This work presents AEGIS, a novel mixed-signal framework for real-time
+anomaly detection by examining sensor stream statistics. AEGIS utilizes Kernel
+Density Estimation (KDE)-based non-parametric density estimation to generate a
+real-time statistical model of the sensor data stream. The likelihood estimate
+of the sensor data point can be obtained based on the generated statistical
+model to detect outliers. We present CMOS Gilbert Gaussian cell-based design to
+realize Gaussian kernels for KDE. For outlier detection, the decision boundary
+is defined in terms of kernel standard deviation ($\sigma_{Kernel}$) and
+likelihood threshold ($P_{Thres}$). We adopt a sliding window to update the
+detection model in real-time. We use time-series dataset provided from Yahoo to
+benchmark the performance of AEGIS. A f1-score higher than 0.87 is achieved by
+optimizing parameters such as length of the sliding window and decision
+thresholds which are programmable in AEGIS. Discussed architecture is designed
+using 45nm technology node and our approach on average consumes $\sim$75 $\mu$W
+power at a sampling rate of 2 MHz while using ten recent inlier samples for
+density estimation. \textcolor{red}{Full-version of this research has been
+published at IEEE TVLSI}",2003.10088v1
+2020-03-30,"Efficient nonparametric inference on the effects of stochastic interventions under two-phase sampling, with applications to vaccine efficacy trials","The advent and subsequent widespread availability of preventive vaccines has
+altered the course of public health over the past century. Despite this
+success, effective vaccines to prevent many high-burden diseases, including
+HIV, have been slow to develop. Vaccine development can be aided by the
+identification of immune response markers that serve as effective surrogates
+for clinically significant infection or disease endpoints. However, measuring
+immune response marker activity is often costly, which has motivated the usage
+of two-phase sampling for immune response evaluation in clinical trials of
+preventive vaccines. In such trials, the measurement of immunological markers
+is performed on a subset of trial participants, where enrollment in this second
+phase is potentially contingent on the observed study outcome and other
+participant-level information. We propose nonparametric methodology for
+efficiently estimating a counterfactual parameter that quantifies the impact of
+a given immune response marker on the subsequent probability of infection.
+Along the way, we fill in theoretical gaps pertaining to the asymptotic
+behavior of nonparametric efficient estimators in the context of two-phase
+sampling, including a multiple robustness property enjoyed by our estimators.
+Techniques for constructing confidence intervals and hypothesis tests are
+presented, and an open source software implementation of the methodology, the
+txshift R package, is introduced. We illustrate the proposed techniques using
+data from a recent preventive HIV vaccine efficacy trial.",2003.13771v2
+2020-04-05,Effects of the Affordable Care Act Dependent Coverage Mandate on Health Insurance Coverage for Individuals in Same-Sex Couples,"A large body of research documents that the 2010 dependent coverage mandate
+of the Affordable Care Act was responsible for significantly increasing health
+insurance coverage among young adults. No prior research has examined whether
+sexual minority young adults also benefitted from the dependent coverage
+mandate, despite previous studies showing lower health insurance coverage among
+sexual minorities and the fact that their higher likelihood of strained
+relationships with their parents might predict a lower ability to use parental
+coverage. Our estimates from the American Community Surveys using
+difference-in-differences and event study models show that men in same-sex
+couples age 21-25 were significantly more likely to have any health insurance
+after 2010 compared to the associated change for slightly older 27 to
+31-year-old men in same-sex couples. This increase is concentrated among
+employer-sponsored insurance, and it is robust to permutations of time periods
+and age groups. Effects for women in same-sex couples and men in different-sex
+couples are smaller than the associated effects for men in same-sex couples.
+These findings confirm the broad effects of expanded dependent coverage and
+suggest that eliminating the federal dependent mandate could reduce health
+insurance coverage among young adult sexual minorities in same-sex couples.",2004.02296v1
+2020-04-07,A general framework for inference on algorithm-agnostic variable importance,"In many applications, it is of interest to assess the relative contribution
+of features (or subsets of features) toward the goal of predicting a response
+-- in other words, to gauge the variable importance of features. Most recent
+work on variable importance assessment has focused on describing the importance
+of features within the confines of a given prediction algorithm. However, such
+assessment does not necessarily characterize the prediction potential of
+features, and may provide a misleading reflection of the intrinsic value of
+these features. To address this limitation, we propose a general framework for
+nonparametric inference on interpretable algorithm-agnostic variable
+importance. We define variable importance as a population-level contrast
+between the oracle predictiveness of all available features versus all features
+except those under consideration. We propose a nonparametric efficient
+estimation procedure that allows the construction of valid confidence
+intervals, even when machine learning techniques are used. We also outline a
+valid strategy for testing the null importance hypothesis. Through simulations,
+we show that our proposal has good operating characteristics, and we illustrate
+its use with data from a study of an antibody against HIV-1 infection.",2004.03683v2
+2020-04-15,Magic DIAMOND: Multi-Fascicle Diffusion Compartment Imaging with Tensor Distribution Modeling and Tensor-Valued Diffusion Encoding,"Diffusion tensor imaging provides increased sensitivity to microstructural
+tissue changes compared to conventional anatomical imaging but also presents
+limited specificity. To tackle this problem, the DIAMOND model subdivides the
+voxel content into diffusion compartments and draws from diffusion-weighted
+data to estimate compartmental non-central matrix-variate Gamma distribution of
+diffusion tensors, thereby resolving crossing fascicles while accounting for
+their respective heterogeneity. Alternatively, tensor-valued diffusion encoding
+defines new acquisition schemes tagging specific features of the intra-voxel
+diffusion tensor distribution directly from the outcome of the measurement.
+However, the impact of such schemes on estimating brain microstructural
+features has only been studied in a handful of parametric single-fascicle
+models. In this work, we derive a general Laplace transform for the non-central
+matrix-variate Gamma distribution, which enables the extension of DIAMOND to
+tensor-valued encoded data. We then evaluate this ""Magic DIAMOND"" model in
+silico and in vivo on various combinations of tensor-valued encoded data.
+Assessing uncertainty on parameter estimation via stratified bootstrap, we
+investigate both voxel-based and fixel-based metrics by carrying out multi-peak
+tractography. We show that our estimated metrics can be mapped along tracks
+robustly across regions of fiber crossing, which opens new perspectives for
+tractometry and microstructure mapping along specific white-matter tracts.",2004.07340v2
+2020-04-16,Measuring Human and Economic Activity from Satellite Imagery to Support City-Scale Decision-Making during COVID-19 Pandemic,"The COVID-19 outbreak forced governments worldwide to impose lockdowns and
+quarantines to prevent virus transmission. As a consequence, there are
+disruptions in human and economic activities all over the globe. The recovery
+process is also expected to be rough. Economic activities impact social
+behaviors, which leave signatures in satellite images that can be automatically
+detected and classified. Satellite imagery can support the decision-making of
+analysts and policymakers by providing a different kind of visibility into the
+unfolding economic changes. In this work, we use a deep learning approach that
+combines strategic location sampling and an ensemble of lightweight
+convolutional neural networks (CNNs) to recognize specific elements in
+satellite images that could be used to compute economic indicators based on it,
+automatically. This CNN ensemble framework ranked third place in the US
+Department of Defense xView challenge, the most advanced benchmark for object
+detection in satellite images. We show the potential of our framework for
+temporal analysis using the US IARPA Function Map of the World (fMoW) dataset.
+We also show results on real examples of different sites before and after the
+COVID-19 outbreak to illustrate different measurable indicators. Our code and
+annotated high-resolution aerial scenes before and after the outbreak are
+available on GitHub (https://github.com/maups/covid19-satellite-analysis).",2004.07438v4
+2020-04-16,Subjectifying Objectivity: Delineating Tastes in Theoretical Quantum Gravity Research,"Research in Theoretical Quantum Gravity has continued expansively even as it
+has become detached from classic arbiters of research such as direct empirical
+falsification. This makes it an interesting test case for social-scientific
+theories of what motivates and mediates contemporary scientific research and
+the nature of scientific objectivity. For our empirical investigation, we
+conducted 50 semi-structured interviews with researchers in the rival camps of
+String Theory and Loop Quantum Gravity, coded a subset for reoccurring themes,
+and subjected the resulting data to statistical analysis. Theoretically, we
+mobilize aspects of Daston and Galison's depiction of the scientific self and
+its relation to epistemic virtues, Pierre Bourdieu's field-centered account of
+social space, and Kantian notions of aesthetics in order to delineate the
+subjective tastes and the related process of collective consensus-making in
+contemporary quantum gravity research. We make two key contributions. First,
+our analysis sheds light on the inner workings of the field by connecting its
+internal epistemic struggles with relevant social-scientific theories. For
+example, we are able to suggest an explanation for how one approach, String
+Theory, has become so dominant. Second, our application of theories of social
+reproduction to the substance of scientific inquiry merits some substantive
+generalizations to Daston and Galison's framework. Most significantly, we
+propose as an addendum to their progression the notion of objectivity through
+intersubjectivity: objectivity obtained not through the suppression of the self
+but by its (regulated) pluralistic expression and performance.",2004.07450v2
+2020-04-22,Excitation of high-frequency magnon modes in magnetoelastic films by short strain pulses,"Development of energy efficient techniques for generation of spin waves
+(magnons) is important for implementation of low-dissipation spin-wave-based
+logic circuits and memory elements. A promising approach to achieve this goal
+is based on the injection of short strain pulses into ferromagnetic films with
+a strong magnetoelastic coupling between spins and strains. Here we report
+micromagnetoelastic simulations of the magnetization and strain dynamics
+excited in Fe$_{81}$Ga$_{19}$ films by picosecond and nanosecond acoustic
+pulses created in a GaAs substrate by a transducer subjected to an optical or
+electrical impulse. The simulations performed via the numerical solution of the
+coupled Landau-Lifshitz-Gilbert and elastodynamic equations show that the
+injected strain pulse induces an inhomogeneous magnetization precession in the
+ferromagnetic film. The precession lasts up to 1 ns and can be treated as a
+superposition of magnon modes having the form of standing spin waves. For
+Fe$_{81}$Ga$_{19}$ films with nanoscale thickness, up to seven (six) distinct
+modes have been revealed under free-surface (pinning) magnetic boundary
+conditions. Remarkably, magnon modes with frequencies over 1 THz can be excited
+by acoustic pulses with an appropriate shape and duration in the films
+subjected to a moderate external magnetic field. This finding shows that short
+strain pulses represent a promising tool for the generation of THz spin waves
+necessary for the implementation of high-speed magnonic devices.",2004.10838v1
+2020-04-23,Correlation-driven eightfold magnetic anisotropy in a two-dimensional oxide monolayer,"Engineering magnetic anisotropy in two-dimensional systems has enormous
+scientific and technological implications. The uniaxial anisotropy universally
+exhibited by two-dimensional magnets has only two stable spin directions,
+demanding 180 degrees spin switching between states. We demonstrate a novel
+eightfold anisotropy in magnetic SrRuO3 monolayers by inducing a spin
+reorientation in (SrRuO3)1/(SrTiO3)N superlattices, in which the magnetic easy
+axis of Ru spins is transformed from uniaxial <001> direction (N = 1 and 2) to
+eightfold <111> directions (N = 3, 4 and 5). This eightfold anisotropy enables
+71 and 109 degrees spin switching in SrRuO3 monolayers, analogous to 71 and 109
+degrees polarization switching in ferroelectric BiFeO3. First-principle
+calculations reveal that increasing the SrTiO3 layer thickness induces an
+emergent correlation-driven orbital ordering, tuning spin-orbit interactions
+and reorienting the SrRuO3 monolayer easy axis. Our work demonstrates that
+correlation effects can be exploited to substantially change spin-orbit
+interactions, stabilizing unprecedented properties in two-dimensional magnets
+and opening rich opportunities for low-power, multi-state device applications.",2004.10939v1
+2020-04-27,"Dynamic Predictions of Postoperative Complications from Explainable, Uncertainty-Aware, and Multi-Task Deep Neural Networks","Accurate prediction of postoperative complications can inform shared
+decisions regarding prognosis, preoperative risk-reduction, and postoperative
+resource use. We hypothesized that multi-task deep learning models would
+outperform random forest models in predicting postoperative complications, and
+that integrating high-resolution intraoperative physiological time series would
+result in more granular and personalized health representations that would
+improve prognostication compared to preoperative predictions. In a longitudinal
+cohort study of 56,242 patients undergoing 67,481 inpatient surgical procedures
+at a university medical center, we compared deep learning models with random
+forests for predicting nine common postoperative complications using
+preoperative, intraoperative, and perioperative patient data. Our study
+indicated several significant results across experimental settings that suggest
+the utility of deep learning for capturing more precise representations of
+patient health for augmented surgical decision support. Multi-task learning
+improved efficiency by reducing computational resources without compromising
+predictive performance. Integrated gradients interpretability mechanisms
+identified potentially modifiable risk factors for each complication. Monte
+Carlo dropout methods provided a quantitative measure of prediction uncertainty
+that has the potential to enhance clinical trust. Multi-task learning,
+interpretability mechanisms, and uncertainty metrics demonstrated potential to
+facilitate effective clinical implementation.",2004.12551v2
+2020-05-08,Tree! I am no Tree! I am a Low Dimensional Hyperbolic Embedding,"Given data, finding a faithful low-dimensional hyperbolic embedding of the
+data is a key method by which we can extract hierarchical information or learn
+representative geometric features of the data. In this paper, we explore a new
+method for learning hyperbolic representations by taking a metric-first
+approach. Rather than determining the low-dimensional hyperbolic embedding
+directly, we learn a tree structure on the data. This tree structure can then
+be used directly to extract hierarchical information, embedded into a
+hyperbolic manifold using Sarkar's construction \cite{sarkar}, or used as a
+tree approximation of the original metric. To this end, we present a novel fast
+algorithm \textsc{TreeRep} such that, given a $\delta$-hyperbolic metric (for
+any $\delta \geq 0$), the algorithm learns a tree structure that approximates
+the original metric. In the case when $\delta = 0$, we show analytically that
+\textsc{TreeRep} exactly recovers the original tree structure. We show
+empirically that \textsc{TreeRep} is not only many orders of magnitude faster
+than previously known algorithms, but also produces metrics with lower average
+distortion and higher mean average precision than most previous algorithms for
+learning hyperbolic embeddings, extracting hierarchical information, and
+approximating metrics via tree metrics.",2005.03847v4
+2020-07-08,On the production of He$^+$ of solar origin in the solar wind,"Solar wind measurements in the heliosphere are predominantly comprised of
+protons, alphas, and minor elements in a highly ionized state. The majority of
+low charge states, such as He$^{+}$, measured in situ are often attributed to
+pick up ions of non-solar origin. However, through inspection of the velocity
+distribution functions of near Earth measurements, we find a small but
+significant population of He$^+$ ions in the normal solar wind whose properties
+indicate that it originated from the Sun and has evolved as part of the normal
+solar wind. Current ionization models, largely governed by electron impact and
+radiative ionization and recombination processes, underestimate this population
+by several orders of magnitude. Therefore, to reconcile the singly ionized He
+observed, we investigate recombination of solar He$^{2+}$ through charge
+exchange with neutrals from circumsolar dust as a possible formation mechanism
+of solar He$^{+}$. We present an empirical profile of neutrals necessary for
+charge exchange to become an effective vehicle to recombine He$^{2+}$ to
+He$^{+}$ such that it meets observational He$^{+}$ values. We find the
+formation of He$^{+}$ is not only sensitive to the density of neutrals but also
+to the inner boundary of the neutral distribution encountered along the solar
+wind path. However, further observational constraints are necessary to confirm
+that the interaction between solar $\alpha$ particles and dust neutrals is the
+primary source of the He$^{+}$ observations.",2007.04402v2
+2020-07-28,Towers and the first-order theory of hyperbolic groups,"This paper is devoted to the first-order theory of torsion-free hyperbolic
+groups. One of its purposes is to review some results and to provide precise
+and correct statements and definitions, as well as some proofs and new results.
+  A key concept is that of a tower (Sela) or NTQ system
+(Kharlampovich-Myasnikov). We discuss them thoroughly.
+  We state and prove a new general theorem which unifies several results in the
+literature: elementarily equivalent torsion-free hyperbolic groups have
+isomorphic cores (Sela); if $H$ is elementarily embedded in a torsion-free
+hyperbolic group $G$, then $G$ is a tower over $H$ relative to $H$ (Perin);
+free groups (Perin-Sklinos, Ould-Houcine), and more generally free products of
+prototypes and free groups, are homogeneous.
+  The converse to Sela and Perin's results just mentioned is true. This follows
+from the solution to Tarski's problem on elementary equivalence of free groups,
+due independently to Sela and Kharlampovich-Myasnikov, which we treat as a
+black box throughout the paper.
+  We present many examples and counterexamples, and we prove some new
+model-theoretic results. We characterize prime models among torsion-free
+hyperbolic groups, and minimal models among elementarily free groups. Using
+Fra\""iss\'e's method, we associate to every torsion-free hyperbolic group $H$ a
+unique homogeneous countable group $\mathcal{M}$ in which any hyperbolic group
+$H'$ elementarily equivalent to $H$ has an elementary embedding.
+  In an appendix we give a complete proof of the fact, due to Sela, that towers
+over a torsion-free hyperbolic group $H$ are $H$-limit groups.",2007.14148v1
+2020-08-13,Prediction of magnetization dynamics in a reduced dimensional feature space setting utilizing a low-rank kernel method,"We establish a machine learning model for the prediction of the magnetization
+dynamics as function of the external field described by the
+Landau-Lifschitz-Gilbert equation, the partial differential equation of motion
+in micromagnetism. The model allows for fast and accurate determination of the
+response to an external field which is illustrated by a thin-film standard
+problem. The data-driven method internally reduces the dimensionality of the
+problem by means of nonlinear model reduction for unsupervised learning. This
+not only makes accurate prediction of the time steps possible, but also
+decisively reduces complexity in the learning process where magnetization
+states from simulated micromagnetic dynamics associated with different external
+fields are used as input data. We use a truncated representation of kernel
+principal components to describe the states between time predictions. The
+method is capable of handling large training sample sets owing to a low-rank
+approximation of the kernel matrix and an associated low-rank extension of
+kernel principal component analysis and kernel ridge regression. The approach
+entirely shifts computations into a reduced dimensional setting breaking down
+the problem dimension from the thousands to the tens.",2008.05986v3
+2020-07-20,Artificial Intelligence is stupid and causal reasoning won't fix it,"Artificial Neural Networks have reached Grandmaster and even super-human
+performance across a variety of games: from those involving perfect-information
+(such as Go) to those involving imperfect-information (such as Starcraft). Such
+technological developments from AI-labs have ushered concomitant applications
+across the world of business - where an AI brand tag is fast becoming
+ubiquitous. A corollary of such widespread commercial deployment is that when
+AI gets things wrong - an autonomous vehicle crashes; a chatbot exhibits racist
+behaviour; automated credit scoring processes discriminate on gender etc. -
+there are often significant financial, legal and brand consequences and the
+incident becomes major news. As Judea Pearl sees it, the underlying reason for
+such mistakes is that, 'all the impressive achievements of deep learning amount
+to just curve fitting'. The key, Judea Pearl suggests, is to replace reasoning
+by association with causal-reasoning - the ability to infer causes from
+observed phenomena. It is a point that was echoed by Gary Marcus and Ernest
+Davis in a recent piece for the New York Times: 'we need to stop building
+computer systems that merely get better and better at detecting statistical
+patterns in data sets - often using an approach known as Deep Learning - and
+start building computer systems that from the moment of their assembly innately
+grasp three basic concepts: time, space and causality'. In this paper,
+foregrounding what in 1949 Gilbert Ryle termed a category mistake, I will offer
+an alternative explanation for AI errors: it is not so much that AI machinery
+cannot grasp causality, but that AI machinery - qua computation - cannot
+understand anything at all.",2008.07371v1
+2020-08-19,Dynamical decoupling in interacting systems: applications to signal-enhanced hyperpolarized readout,"Methods that preserve coherence broadly impact all quantum information
+processing and metrology applications. Dynamical decoupling methods accomplish
+this by protecting qubits in noisy environments but are typically constrained
+to the limit where the qubits themselves are non-interacting. Here we consider
+the alternate regime wherein the inter-qubit couplings are of the same order as
+dephasing interactions with the environment. We propose and demonstrate a
+multi-pulse protocol that protects transverse spin states by suitably
+Hamiltonian engineering the inter-spin coupling while simultaneously
+suppressing dephasing noise on the qubits. We benchmark the method on 13C
+nuclear spin qubits in diamond, dipolar coupled to each other and embedded in a
+noisy electronic spin bath, and hyperpolarized via optically pumped NV centers.
+We observe effective state lifetimes of 13C nuclei $T_2^{\prime}\approx$2.5s at
+room temperature, an extension of over 4700-fold over the conventional
+$T_2^{\ast}$ free induction decay. The spins are continuously interrogated
+during the applied quantum control, resulting in 13C NMR line narrowing and an
+$>$500-fold boost in SNR due to the lifetime extension. Together with
+hyperpolarization spin interrogation is accelerated by $>10^{11}$ over
+conventional 7T NMR. This work suggests strategies for the dynamical decoupling
+of coupled qubit systems with applications in a variety of experimental
+platforms.",2008.08323v1
+2020-08-30,Microwave and spin transfer torque driven coherent control in ferromagnets,"Coherent control is a method used to manipulate the state of matter using
+oscillatory electromagnetic radiation which relies on the non-adiabatic
+interaction. It is commonly applied in quantum processing applications. This
+technique is interesting in the context of ferromagnetic materials because of
+the ability to combine it with spintronics for the purpose of fundamental spin
+transport research, low-power information processing, and potentially future
+quantum bit (Qubit) applications. In this work we address the theoretical
+grounds of coherent manipulation in practical ferromagnetic systems. We study
+electromagnetic radiation driven interaction that is enhanced in the presence
+of spin polarized currents and map the conditions that allow coherent
+manipulation for which Rabi oscillations take place. The role of the magnetic
+anisotropy field is shown to act as an additional oscillatory driving field. We
+discuss the Gilbert losses in the context of effective coherence decay rates
+and show that it is possible to control these rates by application of a static
+spin current. The case of coherent manipulation using oscillatory spin currents
+that is free of radiation is discussed as well. Our work paves the way towards
+spin current amplification as well as radiation-free coherent control schemes
+that may potentially lead to novel Qubits that are robust and scalable.",2008.13139v3
+2020-08-31,Philosophy-Guided Modelling and Implementation of Adaptation and Control in Complex Systems,"Control was from its very beginning an important concept in cybernetics.
+Later on, with the works of W. Ross Ashby, for example, biological concepts
+such as adaptation were interpreted in the light of cybernetic systems theory.
+Adaptation is the process by which a system is capable of regulating or
+controlling itself in order to adapt to changes of its inner and outer
+environment maintaining a homeostatic state. In earlier works we have developed
+a system metamodel that on the one hand refers to cybernetic concepts such as
+structure, operation, and system, and on the other to the philosophy of
+individuation of Gilbert Simondon. The result is the so-called allagmatic
+method that is capable of creating concrete models of systems such as
+artificial neural networks and cellular automata starting from abstract
+building blocks. In this paper, we add to our already existing method the
+cybernetic concepts of control and especially adaptation. In regard to the
+system metamodel, we rely again on philosophical theories, this time the
+philosophy of organism of Alfred N. Whitehead. We show how these new
+meta-theoretical concepts are described formally and how they are implemented
+in program code. We also show what role they play in simple experiments. We
+conclude that philosophical abstract concepts help to better understand the
+process of creating computer models and their control and adaptation. In the
+outlook we discuss how the allagmatic method needs to be extended in order to
+cover the field of complex systems and Norbert Wiener's ideas on control.",2009.00110v4
+2020-09-02,X-ray linear dichroic ptychography,"Biominerals such as seashells, corals skeletons, bone, and enamel are
+optically anisotropic crystalline materials with unique nano- and micro-scale
+organization that translates into exceptional macroscopic mechanical
+properties, providing inspiration for engineering new and superior biomimetic
+structures. Here we use particles of Seriatopora aculeata coral skeleton as a
+model and demonstrate, for the first time, x-ray linear dichroic ptychography.
+We map the aragonite (CaCO3) crystal c-axis orientations in coral skeleton with
+35 nm spatial resolution. Linear dichroic phase imaging at the O K-edge energy
+shows strong polarization-dependent contrast and reveals the presence of both
+narrow (< 35{\deg}) and wide (> 35{\deg}) c-axis angular spread in
+sub-micrometer coral particles. These x-ray ptychography results were
+corroborated using 4D scanning transmission electron nano-diffraction on the
+same particles. Evidence of co-oriented but disconnected corallite sub-domains
+indicates jagged crystal boundaries consistent with formation by amorphous
+nanoparticle attachment. Looking forward, we anticipate that x-ray linear
+dichroic ptychography can be applied to study nano-crystallites, interfaces,
+nucleation and mineral growth of optically anisotropic materials with sub-ten
+nanometers spatial resolution in three dimensions.",2009.01093v1
+2020-09-18,The effect of the surface magnetic anisotropy of the neodymium atoms on the coercivity in the neodymium permanent magnet,"The Nd permanent magnet (Nd$_{2}$Fe$_{14}$B) is an indispensable material
+used in modern energy conversion devices. The realization of high coercivity at
+finite temperatures is a burning issue. One of the important ingredients for
+controlling the coercive force is the surface property of magnetic grains. It
+has been reported by first-principles studies that the Nd atoms in the first
+(001) surface layer facing the vacuum have in-plane anisotropy perpendicular to
+the $c$ axis, which may decrease the coercivity. Focusing on the surface
+anisotropy effect on the coercivity, we examine the coercivity at zero and
+finite temperatures by using an atomistic model reflecting the lattice
+structure of the Nd magnet with a stochastic Landau-Lifshitz-Gilbert equation
+method. We study general three cases, in which the Nd atoms in surface layers
+have (1) no anisotropy, (2) in-plane anisotropy, and (3) reinforced anisotropy
+for two types of surfaces, (001) and (100) surfaces. We find that in contrast
+to the zero-temperature case, due to the thermal fluctuation effect, the
+modification of only the first surface layer has little effect on the
+coercivity at finite temperatures. However, the modification of a few layers
+results in significant effects. We discuss the details of the dependence of the
+coercivity on temperature, type of surface, and modified layer depth, and also
+the features of domain growth in magnetization reversal.",2009.08572v1
+2020-09-28,Precise control of $J_\mathrm{eff}=1/2$ magnetic properties in Sr$_2$IrO$_4$ epitaxial thin films by variation of strain and thin film thickness,"We report on a comprehensive investigation of the effects of strain and film
+thickness on the structural and magnetic properties of epitaxial thin films of
+the prototypal $J_\mathrm{eff}=1/2$ compound Sr$_2$IrO$_4$ by advanced X-ray
+scattering. We find that the Sr$_2$IrO$_4$ thin films can be grown fully
+strained up to a thickness of 108 nm. By using X-ray resonant scattering, we
+show that the out-of-plane magnetic correlation length is strongly dependent on
+the thin film thickness, but independent of the strain state of the thin films.
+This can be used as a finely tuned dial to adjust the out-of-plane magnetic
+correlation length and transform the magnetic anisotropy from two-dimensional
+(2D) to three-dimensional (3D) behavior by incrementing film thickness. These
+results provide a clearer picture for the systematic control of the magnetic
+degrees of freedom in epitaxial thin films of Sr$_2$IrO$_4$ and bring to light
+the potential for a rich playground to explore the physics of $5d$-transition
+metal compounds.",2009.13185v1
+2020-10-03,"WinterLab: Developing a low-cost, portable experiment platform to encourage engagement in the electronics lab","Encouraging student engagement is a key aim in any educational setting, and
+allowing students the freedom to pursue their own methods of solving problems
+through independent experimentation has been shown to markedly improve this. In
+many contexts, however, allowing students this flexibility in their learning is
+hampered by constraints of the material itself, such as in the electronics
+laboratory, where expensive and bulky equipment confines the learning
+environment to the laboratory room. Finding ourselves in the position of
+teaching one such laboratory course at the undergraduate level, we sought to
+encourage students to learn through independent investigation and the pursuit
+of personal projects, by providing a more flexible and inquiry-based learning
+environment and allowing them to take their measurement equipment -- and their
+learning -- beyond the laboratory itself. We present this project as a case of
+design both for and by students, with the lead designer undertaking the project
+after attending the course in question, and pursuing its development as a
+foundational step in their graduate career. We discuss the challenges and
+opportunities we encountered over the course of the design and development
+process, and the eventual key output of the project: a portable, low-cost,
+integrated electronics experimentation platform called the Winterlab board.",2010.01426v2
+2020-10-16,Hyperspectral interference tomography of nacre,"Structural characterization of biologically formed materials is essential for
+understanding biological phenomena and their environment, and generating new
+bio-inspired engineering concepts. For example, nacre -- formed by mollusks in
+the ocean -- encodes local environmental conditions throughout its formation
+and has exceptional strength due to its nanoscale brick-and-mortar structure.
+This layered structure, comprising transparent aragonite tablets bonded with an
+ultra-thin organic polymer, also results in stunning interference colors.
+Existing methods of structural characterization of nacre rely on some form of
+cross-sectional analysis, such as scanning electron microscopy or
+polarization-dependent imaging contrast (PIC) mapping. However, these
+techniques are destructive and too time- and resource-intensive to analyze
+large sample areas. Here we present an all-optical, rapid, and non-destructive
+imaging technique -- hyperspectral interference tomography (HIT) -- to
+spatially map the structural parameters of nacre and other disordered layered
+materials. We combined hyperspectral imaging with optical-interference modeling
+to infer the mean tablet thickness and disordering of nacre layers across
+entire mollusk shells at various stages of development, observing a previously
+unknown relationship between the growth of the mollusk and tablet thickness.
+Our rapid, inexpensive, and nondestructive method can be readily applied to
+in-field studies.",2010.08170v1
+2020-11-03,Recent results for the Landau-Lifshitz equation,"We give a survey on some recent results concerning the Landau-Lifshitz
+equation, a fundamental nonlinear PDE with a strong geometric content,
+describing the dynamics of the magnetization in ferromagnetic materials. We
+revisit the Cauchy problem for the anisotropic Landau-Lifshitz equation,
+without dissipation, for smooth solutions, and also in the energy space in
+dimension one. We also examine two approximations of the Landau-Lifshitz
+equation given by of the Sine-Gordon equation and cubic Schr\""odinger
+equations, arising in certain singular limits of strong easy-plane and
+easy-axis anisotropy, respectively.
+  Concerning localized solutions, we review the orbital and asymptotic
+stability problems for a sum of solitons in dimension one, exploiting the
+variational nature of the solitons in the hydrodynamical framework.
+  Finally, we survey results concerning the existence, uniqueness and stability
+of self-similar solutions (expanders and shrinkers) for the isotropic
+Landau-Lifshitz equation with Gilbert term. Since expanders are associated with
+a singular initial condition with a jump discontinuity, we also review their
+well-posedness in spaces linked to the BMO space.",2011.01692v3
+2020-11-10,The Virtual Goniometer: A new method for measuring angles on 3D models of fragmentary bone and lithics,"The contact goniometer is a commonly used tool in lithic and
+zooarchaeological analysis, despite suffering from a number of shortcomings due
+to the physical interaction between the measuring implement, the object being
+measured, and the individual taking the measurements. However, lacking a simple
+and efficient alternative, researchers in a variety of fields continue to use
+the contact goniometer to this day. In this paper, we present a new goniometric
+method that we call the virtual goniometer, which takes angle measurements
+virtually on a 3D model of an object. The virtual goniometer allows for rapid
+data collection, and for the measurement of many angles that cannot be
+physically accessed by a manual goniometer. We compare the intra-observer
+variability of the manual and virtual goniometers, and find that the virtual
+goniometer is far more consistent and reliable. Furthermore, the virtual
+goniometer allows for precise replication of angle measurements, even among
+multiple users, which is important for reproducibility of goniometric-based
+research. The virtual goniometer is available as a plug-in in the open source
+mesh processing packages Meshlab and Blender, making it easily accessible to
+researchers exploring the potential for goniometry to improve archaeological
+methods and address anthropological questions.",2011.04898v2
+2020-11-17,Competing energy scales in topological superconducting heterostructures,"Artificially engineered topological superconductivity has emerged as a viable
+route to create Majorana modes, exotic quasiparticles which have raised great
+expectations for storing and manipulating information in topological quantum
+computational schemes. The essential ingredients for their realization are spin
+non-degenerate metallic states proximitized to an s-wave superconductor. In
+this context, proximity-induced superconductivity in materials with a sizable
+spin-orbit coupling has been heavily investigated in recent years. Although
+there is convincing evidence that superconductivity may indeed be induced, it
+has been difficult to elucidate its topological nature. In this work, we
+systematically engineer an artificial topological superconductor by
+progressively introducing superconductivity (Nb) into metals with strong
+spin-orbital coupling (Pt) and 3D topological surface states (Bi2Te3). Through
+a longitudinal study of the character of superconducting vortices within s-wave
+superconducting Nb and proximity-coupled Nb/Pt and Nb/Bi2Te3, we detect the
+emergence of a zero-bias peak that is directly linked to the presence of
+topological surface states. Supported by a detailed theoretical model, our
+results are rationalized in terms of competing energy trends which are found to
+impose an upper limit to the size of the minigap separating Majorana and
+trivial modes, its size being ultimately linked to fundamental materials
+properties.",2011.08812v1
+2020-12-01,Phase-field modeling of biomineralization in mollusks and corals: Microstructure vs. formation mechanism,"While biological crystallization processes have been studied on the
+microscale extensively, models addressing the mesoscale aspects of such
+phenomena are rare. In this work, we investigate whether the phase-field theory
+developed in materials science for describing complex polycrystalline
+structures on the mesoscale can be meaningfully adapted to model
+crystallization in biological systems. We demonstrate the abilities of the
+phase-field technique by modeling a range of microstructures observed in
+mollusk shells and coral skeletons, including granular, prismatic,
+sheet/columnar nacre, and sprinkled spherulitic structures. We also compare two
+possible micromechanisms of calcification: the classical route via ion-by-ion
+addition from a fluid state and a non-classical route, crystallization of an
+amorphous precursor deposited at the solidification front. We show that with
+appropriate choice of the model parameters microstructures similar to those
+found in biomineralized systems can be obtained along both routes, though the
+timescale of the non-classical route appears to be more realistic. The
+resemblance of the simulated and natural biominerals suggests that, underneath
+the immense biological complexity observed in living organisms, the underlying
+design principles for biological structures may be understood with simple math,
+and simulated by phase-field theory.",2012.00666v1
+2020-12-02,Symmetry of the Magnetoelastic Interaction of Rayleigh and Shear Horizontal Magnetoacoustic Waves in Nickel Thin Films on LiTaO$_3$,"We study the interaction of Rayleigh and shear horizontal surface acoustic
+waves (SAWs) with spin waves in thin Ni films on a piezoelectric LiTaO$_3$
+substrate, which supports both SAW modes simultaneously. Because Rayleigh and
+shear horizontal modes induce different strain components in the Ni thin films,
+the symmetries of the magnetoelastic driving fields, of the magnetoelastic
+response, and of the transmission nonreciprocity differ for both SAW modes. Our
+experimental findings are well explained by a theoretical model based on a
+modified Landau--Lifshitz--Gilbert approach. We show that the symmetries of the
+magnetoelastic response driven by Rayleigh- and shear horizontal SAWs
+complement each other, which makes it possible to excite spin waves for any
+relative orientation of magnetization and SAW propagation direction and,
+moreover, can be utilized to characterize surface strain components of unknown
+acoustic wave modes.",2012.01055v2
+2020-12-03,Localization of Malaria Parasites and White Blood Cells in Thick Blood Smears,"Effectively determining malaria parasitemia is a critical aspect in assisting
+clinicians to accurately determine the severity of the disease and provide
+quality treatment. Microscopy applied to thick smear blood smears is the de
+facto method for malaria parasitemia determination. However, manual
+quantification of parasitemia is time consuming, laborious and requires
+considerable trained expertise which is particularly inadequate in highly
+endemic and low resourced areas. This study presents an end-to-end approach for
+localisation and count of malaria parasites and white blood cells (WBCs) which
+aid in the effective determination of parasitemia; the quantitative content of
+parasites in the blood. On a dataset of slices of images of thick blood smears,
+we build models to analyse the obtained digital images. To improve model
+performance due to the limited size of the dataset, data augmentation was
+applied. Our preliminary results show that our deep learning approach reliably
+detects and returns a count of malaria parasites and WBCs with a high precision
+and recall. We also evaluate our system against human experts and results
+indicate a strong correlation between our deep learning model counts and the
+manual expert counts (p=0.998 for parasites, p=0.987 for WBCs). This approach
+could potentially be applied to support malaria parasitemia determination
+especially in settings that lack sufficient Microscopists.",2012.01994v1
+2020-12-05,Age-Optimal Low-Power Status Update over Time-Correlated Fading Channel,"In this paper, we consider transmission scheduling in a status update system,
+where updates are generated periodically and transmitted over a Gilbert-Elliott
+fading channel. The goal is to minimize the long-run average age of information
+(AoI) at the destination under an average energy constraint. We consider two
+practical cases to obtain channel state information (CSI): (i) \emph{without
+channel sensing} and (ii) \emph{with delayed channel sensing}. For case (i),
+the channel state is revealed when an ACK/NACK is received at the transmitter
+following a transmission, but when no transmission occurs, the channel state is
+not revealed. Thus, we have to design schemes that balance tradeoffs across
+energy, AoI, channel exploration, and channel exploitation. The problem is
+formulated as a constrained partially observable Markov decision process
+problem (POMDP). To reduce algorithm complexity, we show that the optimal
+policy is a randomized mixture of no more than two stationary deterministic
+policies each of which is of a threshold-type in the belief on the channel. For
+case (ii), (delayed) CSI is available at the transmitter via channel sensing.
+In this case, the tradeoff is only between the AoI and energy consumption and
+the problem is formulated as a constrained MDP. The optimal policy is shown to
+have a similar structure as in case (i) but with an AoI associated threshold.
+Finally, the performance of the proposed structure-aware algorithms is
+evaluated numerically and compared with a Greedy policy.",2012.02958v2
+2020-11-30,Procode: the Swiss Multilingual Solution for Automatic Coding and Recoding of Occupations and Economic Activities,"Objective. Epidemiological studies require data that are in alignment with
+the classifications established for occupations or economic activities. The
+classifications usually include hundreds of codes and titles. Manual coding of
+raw data may result in misclassification and be time consuming. The goal was to
+develop and test a web-tool, named Procode, for coding of free-texts against
+classifications and recoding between different classifications. Methods. Three
+text classifiers, i.e. Complement Naive Bayes (CNB), Support Vector Machine
+(SVM) and Random Forest Classifier (RFC), were investigated using a k-fold
+cross-validation. 30 000 free-texts with manually assigned classification codes
+of French classification of occupations (PCS) and French classification of
+activities (NAF) were available. For recoding, Procode integrated a workflow
+that converts codes of one classification to another according to existing
+crosswalks. Since this is a straightforward operation, only the recoding time
+was measured. Results. Among the three investigated text classifiers, CNB
+resulted in the best performance, where the classifier predicted accurately
+57-81% and 63-83% classification codes for PCS and NAF, respectively. SVM lead
+to somewhat lower results (by 1-2%), while RFC coded accurately up to 30% of
+the data. The coding operation required one minute per 10 000 records, while
+the recoding was faster, i.e. 5-10 seconds. Conclusion. The algorithm
+integrated in Procode showed satisfactory performance, since the tool had to
+assign the right code by choosing between 500-700 different choices. Based on
+the results, the authors decided to implement CNB in Procode. In future, if
+another classifier shows a superior performance, an update will include the
+required modifications.",2012.07521v1
+2020-12-16,Dynamic clay microstructures emerge via ion complexation waves,"Clays control carbon, water and nutrient transport in the lithosphere,
+promote cloud formation5 and lubricate fault slip through interactions among
+hydrated mineral interfaces. Clay mineral properties are difficult to model
+because their structures are disordered, curved and dynamic. Consequently,
+interactions at the clay mineral-aqueous interface have been approximated using
+electric double layer models based on single crystals of mica and atomistic
+simulations. We discover that waves of complexation dipoles at dynamically
+curving interfaces create an emergent long-range force that drives exfoliation
+and restacking over time- and length-scales that are not captured in existing
+models. Curvature delocalizes electrostatic interactions in ways that
+fundamentally differ from planar surfaces, altering the ratio of ions bound to
+the convex and concave sides of a layer. Multiple-scattering reconstruction of
+low-dose energy-filtered cryo electron tomography enabled direct imaging of ion
+complexes and electrolyte distributions at hydrated and curved mineral
+interfaces with {\aa}ngstrom resolution over micron length scales. Layers
+exfoliate and restack abruptly and repeatedly over timescales that depend
+strongly on the counterion identity, demonstrating that the strong coupling
+between elastic, electrostatic and hydration forces in clays promote collective
+reorganization previously thought to be a feature only of active matter.",2012.09295v1
+2020-12-17,Age-optimal Scheduling over Hybrid Channels,"We consider the problem of minimizing the age of information when a source
+can transmit status updates over two heterogeneous channels. Our work is
+motivated by recent developments in 5G mmWave technology, where transmissions
+may occur over an unreliable but fast (e.g., mmWave) channel or a slow reliable
+(e.g., sub-6GHz) channel. The unreliable channel is modeled as a
+time-correlated Gilbert-Elliot channel at a high rate when the channel is in
+the 'ON' state. The reliable channel provides a deterministic but lower data
+rate. The scheduling strategy determines the channel to be used for
+transmission in each time slot, aiming to minimize the time-average age of
+information (AoI). The optimal scheduling problem is formulated as a Markov
+Decision Process (MDP), which is challenging to solve because super-modularity
+does not hold in a part of the state space. We address this challenge and show
+that a multi-dimensional threshold-type scheduling policy is optimal for
+minimizing the age. By exploiting the structure of the MDP and analyzing the
+discrete-time Markov chains (DTMCs) of the threshold-type policy, we devise a
+low-complexity bisection algorithm to compute the optimal thresholds. We
+compare different scheduling policies using numerical simulations.",2012.09403v6
+2020-12-21,Variations on the Maiani-Testa approach and the inverse problem,"We discuss a method to construct hadronic scattering and decay amplitudes
+from Euclidean correlators, by combining the approach of a regulated inverse
+Laplace transform with the work of Maiani and Testa. Revisiting the original
+result, we observe that the key observation, i.e. that only threshold
+scattering information can be extracted at large separations, can be understood
+by interpreting the correlator as a spectral function, $\rho(\omega)$,
+convoluted with the Euclidean kernel, $e^{- \omega t}$, which is sharply peaked
+at threshold. We therefore consider a modification in which a smooth step
+function, equal to one above a target energy, is inserted in the spectral
+decomposition. This can be achieved either through Backus-Gilbert-like methods
+or more directly using the variational approach. The result is a shifted
+resolution function, such that the large $t$ limit projects onto scattering or
+decay amplitudes above threshold. The utility of this method is highlighted
+through large $t$ expansions of both three- and four-point functions that
+include leading terms proportional to the real and imaginary parts (separately)
+of the target observable. This work also presents new results relevant for the
+un-modified correlator at threshold, including expressions for extracting the
+$N \pi$ scattering length from four-point functions and a new strategy to
+organize the large $t$ expansion that exhibits better convergence than the
+expansion in powers of $1/t$.",2012.11488v1
+2021-01-13,"PID passivity-based droop control of power converters: Large-signal stability, robustness and performance","We present a full review of PID passivity-based controllers (PBC) applied to
+power electronic converters, discussing limitations, unprecedented merits and
+potential improvements in terms of large-signal stability, robustness and
+performance. We provide four main contributions. The nominal case is first
+considered and it is shown, under the assumption of perfect knowledge of the
+system parameters, that the PID-PBC is able to guarantee global exponential
+stability of a desired operating point for any positive gains. Second, we
+analyze robustness of the controller to parameters uncertainty for a specific
+class of power converters, by establishing precise stability margins. Third, we
+propose a modification of the controller by introducing a leakage, in order to
+overcome some of the intrinsic performance and robustness limitations.
+Interestingly, such controller can be interpreted at steady-state as a droop
+between the input and the passive output, similar to traditional primary
+controllers. Fourth, we robustify the design against saturation of the control
+input via an appropriate monotone transformation of the controller. The
+obtained results are thoroughly discussed and validated by simulations on two
+relevant power applications: a dc/dc boost converter and an HVDC grid-connected
+voltage source converter.",2101.05047v2
+2021-02-15,Recent Developments in Blockchain Technology and their Impact on Energy Consumption,"The enormous power consumption of Bitcoin has led to undifferentiated
+discussions in science and practice about the sustainability of blockchain and
+distributed ledger technology in general. However, blockchain technology is far
+from homogeneous - not only with regard to its applications, which now go far
+beyond cryptocurrencies and have reached businesses and the public sector, but
+also with regard to its technical characteristics and, in particular, its power
+consumption. This paper summarizes the status quo of the power consumption of
+various implementations of blockchain technology, with special emphasis on the
+recent 'Bitcoin Halving' and so-called 'zk-rollups'. We argue that although
+Bitcoin and other proof-of-work blockchains do indeed consume a lot of power,
+alternative blockchain solutions with significantly lower power consumption are
+already available today, and new promising concepts are being tested that could
+further reduce in particular the power consumption of large blockchain networks
+in the near future. From this we conclude that although the criticism of
+Bitcoin's power consumption is legitimate, it should not be used to derive an
+energy problem of blockchain technology in general. In many cases in which
+processes can be digitised or improved with the help of more energy-efficient
+blockchain variants, one can even expect net energy savings.",2102.07886v1
+2021-03-11,Toward the Next Generation of News Recommender Systems,"This paper proposes a vision and research agenda for the next generation of
+news recommender systems (RS), called the table d'hote approach. A table d'hote
+(translates as host's table) meal is a sequence of courses that create a
+balanced and enjoyable dining experience for a guest. Likewise, we believe news
+RS should strive to create a similar experience for the users by satisfying the
+news-diet needs of a user. While extant news RS considers criteria such as
+diversity and serendipity, and RS bundles have been studied for other contexts
+such as tourism, table d'hote goes further by ensuring the recommended articles
+satisfy a diverse set of user needs in the right proportions and in a specific
+order. In table d'hote, available articles need to be stratified based on the
+different ways that news can create value for the reader, building from
+theories and empirical research in journalism and user engagement. Using
+theories and empirical research from communication on the uses and
+gratifications (U&G) consumers derive from media, we define two main strata in
+a table d'hote news RS, each with its own substrata: 1) surveillance, which
+consists of information the user needs to know, and 2) serendipity, which are
+the articles offering unexpected surprises. The diversity of the articles
+according to the defined strata and the order of the articles within the list
+of recommendations are also two important aspects of the table d'hote in order
+to give the users the most effective reading experience. We propose our vision,
+link it to the existing concepts in the RS literature, and identify challenges
+for future research.",2103.06909v1
+2021-03-16,Machine learning methods for the prediction of micromagnetic magnetization dynamics,"Machine learning (ML) entered the field of computational micromagnetics only
+recently. The main objective of these new approaches is the automatization of
+solutions of parameter-dependent problems in micromagnetism such as fast
+response curve estimation modeled by the Landau-Lifschitz-Gilbert (LLG)
+equation. Data-driven models for the solution of time- and parameter-dependent
+partial differential equations require high dimensional training
+data-structures. ML in this case is by no means a straight-forward trivial
+task, it needs algorithmic and mathematical innovation. Our work introduces
+theoretical and computational conceptions of certain kernel and neural network
+based dimensionality reduction approaches for efficient prediction of solutions
+via the notion of low-dimensional feature space integration. We introduce
+efficient treatment of kernel ridge regression and kernel principal component
+analysis via low-rank approximation. A second line follows neural network (NN)
+autoencoders as nonlinear data-dependent dimensional reduction for the training
+data with focus on accurate latent space variable description suitable for a
+feature space integration scheme. We verify and compare numerically by means of
+a NIST standard problem. The low-rank kernel method approach is fast and
+surprisingly accurate, while the NN scheme can even exceed this level of
+accuracy at the expense of significantly higher costs.",2103.09079v2
+2021-03-18,Bounding the detection efficiency threshold in Bell tests using multiple copies of the maximally entangled two-qubit state carried by a single pair of particles,"In this paper, we investigate the critical efficiency of detectors to observe
+Bell nonlocality using multiple copies of the maximally entangled two-qubit
+state carried by a single pair of particles, such as hyperentangled states, and
+the product of Pauli measurements. It is known that in a
+Clauser-Horne-Shimony-Holt (CHSH) Bell test the symmetric detection efficiency
+of $82.84\%$ can be tolerated for the two-qubit maximally entangled state. We
+beat this enigmatic threshold by entangling two particles with multiple degrees
+of freedom. The obtained upper bounds of the symmetric detection efficiency
+thresholds are $80.86\%$, $73.99\%$ and $69.29\%$ for two, three and four
+copies of the two-qubit maximally entangled state, respectively. The number of
+measurements and outcomes in the respective cases are 4, 8 and 16. To find the
+improved thresholds, we use large-scale convex optimization tools, which allows
+us to significantly go beyond state-of-the-art results. The proof is exact up
+to three copies, while for four copies it is due to reliable numerical
+computations. Specifically, we used linear programming to obtain the two-copy
+threshold and the corresponding Bell inequality, and convex optimization based
+on Gilbert's algorithm for three and four copies of the two-qubit state. We
+show analytically that the symmetric detection efficiency threshold decays
+exponentially with the number of copies of the two-qubit state. Our techniques
+can also be applied to more general Bell nonlocality scenarios with more than
+two parties.",2103.10413v2
+2021-04-05,When Can Liquid Democracy Unveil the Truth?,"In this paper, we investigate the so-called ODP-problem that has been
+formulated by Caragiannis and Micha [10]. Here, we are in a setting with two
+election alternatives out of which one is assumed to be correct. In ODP, the
+goal is to organise the delegations in the social network in order to maximize
+the probability that the correct alternative, referred to as ground truth, is
+elected. While the problem is known to be computationally hard, we strengthen
+existing hardness results by providing a novel strong approximation hardness
+result: For any positive constant $C$, we prove that, unless $P=NP$, there is
+no polynomial-time algorithm for ODP that achieves an approximation guarantee
+of $\alpha \ge (\ln n)^{-C}$, where $n$ is the number of voters. The reduction
+designed for this result uses poorly connected social networks in which some
+voters suffer from misinformation. Interestingly, under some hypothesis on
+either the accuracies of voters or the connectivity of the network, we obtain a
+polynomial-time $1/2$-approximation algorithm. This observation proves formally
+that the connectivity of the social network is a key feature for the efficiency
+of the liquid democracy paradigm. Lastly, we run extensive simulations and
+observe that simple algorithms (working either in a centralized or
+decentralized way) outperform direct democracy on a large class of instances.
+Overall, our contributions yield new insights on the question in which
+situations liquid democracy can be beneficial.",2104.01828v1
+2021-04-05,Floquet prethermalization with lifetime exceeding 90s in a bulk hyperpolarized solid,"We report the observation of long-lived Floquet prethermal states in a bulk
+solid composed of dipolar-coupled $^{13}$C nuclei in diamond at room
+temperature. For precessing nuclear spins prepared in an initial transverse
+state, we demonstrate pulsed spin-lock Floquet control that prevents their
+decay over multiple-minute long periods. We observe Floquet prethermal
+lifetimes $T_2'\approx$90.9s, extended >60,000-fold over the nuclear free
+induction decay times. The spins themselves are continuously interrogated for
+$\sim$10min, corresponding to the application of $\approx$5.8M control pulses.
+The $^{13}$C nuclei are optically hyperpolarized by lattice Nitrogen Vacancy
+(NV) centers; the combination of hyperpolarization and continuous spin readout
+yields significant signal-to-noise in the measurements. This allows probing the
+Floquet thermalization dynamics with unprecedented clarity. We identify four
+characteristic regimes of the thermalization process, discerning short-time
+transient processes leading to the prethermal plateau, and long-time system
+heating towards infinite temperature. This work points to new opportunities
+possible via Floquet control in networks of dilute, randomly distributed,
+low-sensitivity nuclei. In particular, the combination of minutes-long
+prethermal lifetimes and continuous spin interrogation opens avenues for
+quantum sensors constructed from hyperpolarized Floquet prethermal nuclei.",2104.01988v2
+2021-04-14,Generalized Simple Streaming Codes from MDS Codes,"Streaming codes represent a packet-level FEC scheme for achieving reliable,
+low-latency communication. In the literature on streaming codes, the
+commonly-assumed Gilbert-Elliott channel model, is replaced by a more
+tractable, delay-constrained, sliding-window (DCSW) channel model that can
+introduce either random or burst erasures. The known streaming codes that are
+rate optimal over the DCSW channel model are constructed by diagonally
+embedding a scalar block code across successive packets. These code
+constructions have field size that is quadratic in the delay parameter $\tau$
+and have a somewhat complex structure with an involved decoding procedure. This
+led to the introduction of simple streaming (SS) codes in which diagonal
+embedding is replaced by staggered-diagonal embedding (SDE). The SDE approach
+reduces the impact of a burst of erasures and makes it possible to construct
+near-rate-optimal streaming codes using Maximum Distance Separable (MDS) code
+having linear field size. The present paper takes this development one step
+further, by retaining the staggered-diagonal feature, but permitting the
+placement of more than one code symbol from a given scalar codeword within each
+packet. These generalized, simple streaming codes allow us to improve upon the
+rate of SS codes, while retaining the simplicity of working with MDS codes. We
+characterize the maximum code rate of streaming codes under a constraint on the
+number of contiguous packets over which symbols of the underlying scalar code
+are dispersed. Such a constraint leads to simplified code construction and
+reduced-complexity decoding.",2104.07005v1
+2021-04-22,COVID-19 and Big Data: Multi-faceted Analysis for Spatio-temporal Understanding of the Pandemic with Social Media Conversations,"COVID-19 has been devastating the world since the end of 2019 and has
+continued to play a significant role in major national and worldwide events,
+and consequently, the news. In its wake, it has left no life unaffected. Having
+earned the world's attention, social media platforms have served as a vehicle
+for the global conversation about COVID-19. In particular, many people have
+used these sites in order to express their feelings, experiences, and
+observations about the pandemic. We provide a multi-faceted analysis of
+critical properties exhibited by these conversations on social media regarding
+the novel coronavirus pandemic. We present a framework for analysis, mining,
+and tracking the critical content and characteristics of social media
+conversations around the pandemic. Focusing on Twitter and Reddit, we have
+gathered a large-scale dataset on COVID-19 social media conversations. Our
+analyses cover tracking potential reports on virus acquisition, symptoms,
+conversation topics, and language complexity measures through time and by
+region across the United States. We also present a BERT-based model for
+recognizing instances of hateful tweets in COVID-19 conversations, which
+achieves a lower error-rate than the state-of-the-art performance. Our results
+provide empirical validation for the effectiveness of our proposed framework
+and further demonstrate that social media data can be efficiently leveraged to
+provide public health experts with inexpensive but thorough insight over the
+course of an outbreak.",2104.10807v1
+2021-05-05,exoplanet: Gradient-based probabilistic inference for exoplanet data & other astronomical time series,"""exoplanet"" is a toolkit for probabilistic modeling of astronomical time
+series data, with a focus on observations of exoplanets, using PyMC3 (Salvatier
+et al., 2016). PyMC3 is a flexible and high-performance model-building language
+and inference engine that scales well to problems with a large number of
+parameters. ""exoplanet"" extends PyMC3's modeling language to support many of
+the custom functions and probability distributions required when fitting
+exoplanet datasets or other astronomical time series. While it has been used
+for other applications, such as the study of stellar variability, the primary
+purpose of ""exoplanet"" is the characterization of exoplanets or multiple star
+systems using time-series photometry, astrometry, and/or radial velocity. In
+particular, the typical use case would be to use one or more of these datasets
+to place constraints on the physical and orbital parameters of the system, such
+as planet mass or orbital period, while simultaneously taking into account the
+effects of stellar variability.",2105.01994v2
+2021-05-05,Elemental Abundances in M31: Gradients in the Giant Stellar Stream,"We analyze existing measurements of [Fe/H] and [$\alpha$/Fe] for individual
+red giant branch (RGB) stars in the Giant Stellar Stream (GSS) of M31 to
+determine whether spatial abundance gradients are present. These measurements
+were obtained from low- ($R \sim 3000$) and moderate- ($R \sim 6000$)
+resolution Keck/DEIMOS spectroscopy using spectral synthesis techniques as part
+of the Elemental Abundances in M31 survey. From a sample of 62 RGB stars
+spanning the GSS at 17, 22, and 33 projected kpc, we measure a [Fe/H] gradient
+of $-$0.018 $\pm$ 0.003 dex kpc$^{-1}$ and negligible [$\alpha$/Fe] gradient
+with M31-centric radius. We investigate GSS abundance patterns in the outer
+halo using additional [Fe/H] and [$\alpha$/Fe] measurements for 6 RGB stars
+located along the stream at 45 and 58 projected kpc. These abundances provide
+tentative evidence that the trends in [Fe/H] and [$\alpha$/Fe] beyond 40 kpc in
+the GSS are consistent with those within 33 kpc. We also compare the GSS
+abundances to 65 RGB stars located along the possibly related Southeast (SE)
+shelf substructure at 12 and 18 projected kpc. The abundances of the GSS and SE
+shelf are consistent, supporting a common origin hypothesis, although this
+interpretation may be complicated by the presence of [Fe/H] gradients in the
+GSS. We discuss the abundance patterns in the context of photometric studies
+from the literature and explore implications for the properties of the GSS
+progenitor, suggesting that the high $\langle$[$\alpha$/Fe]$\rangle$ of the GSS
+(+0.40 $\pm$ 0.05 dex) favors a major merger scenario for its formation.",2105.02339v1
+2021-05-17,A Unified Adaptive Recoding Framework for Batched Network Coding,"Batched network coding is a variation of random linear network coding which
+has low computational and storage costs. In order to adapt to random
+fluctuations in the number of erasures in individual batches, it is not optimal
+to recode and transmit the same number of packets for all batches. Different
+distributed optimization models, which are called adaptive recoding schemes,
+were formulated for this purpose. The key component of these optimization
+problems is the expected value of the rank distribution of a batch at the next
+network node, which is also known as the expected rank. In this paper, we put
+forth a unified adaptive recoding framework with an arbitrary recoding field
+size. We show that the expected rank functions are concave when the packet loss
+pattern is a stationary stochastic process, which covers but not limited to
+independent packet loss and Gilbert-Elliott packet loss model. Under this
+concavity assumption, we show that there always exists a solution which not
+only can minimize the randomness on the number of recoded packets but also can
+tolerate rank distribution errors due to inaccurate measurements or limited
+precision of the machine. We provide an algorithm to obtain such an optimal
+optimal solution, and propose tuning schemes that can turn any feasible
+solution into a desired optimal solution.",2105.07614v2
+2021-05-21,Hybrid Machine Learning for Scanning Near-field Optical Spectroscopy,"The underlying physics behind an experimental observation often lacks a
+simple analytical description. This is especially the case for scanning probe
+microscopy techniques, where the interaction between the probe and the sample
+is nontrivial. Realistic modeling to include the details of the probe is always
+exponentially more difficult than its ""spherical cow"" counterparts. On the
+other hand, a well-trained artificial neural network based on real data can
+grasp the hidden correlation between the signal and sample properties. In this
+work, we show that, via a combination of model calculation and experimental
+data acquisition, a physics-infused hybrid neural network can predict the
+tip-sample interaction in the widely used scattering-type scanning near-field
+optical microscope. This hybrid network provides a long-sought solution for
+accurate extraction of material properties from tip-specific raw data. The
+methodology can be extended to other scanning probe microscopy techniques as
+well as other data-oriented physical problems in general.",2105.10551v1
+2021-05-26,Contention Resolution with Predictions,"In this paper, we consider contention resolution algorithms that are
+augmented with predictions about the network. We begin by studying the natural
+setup in which the algorithm is provided a distribution defined over the
+possible network sizes that predicts the likelihood of each size occurring. The
+goal is to leverage the predictive power of this distribution to improve on
+worst-case time complexity bounds. Using a novel connection between contention
+resolution and information theory, we prove lower bounds on the expected time
+complexity with respect to the Shannon entropy of the corresponding network
+size random variable, for both the collision detection and no collision
+detection assumptions. We then analyze upper bounds for these settings,
+assuming now that the distribution provided as input might differ from the
+actual distribution generating network sizes. We express their performance with
+respect to both entropy and the statistical divergence between the two
+distributions -- allowing us to quantify the cost of poor predictions. Finally,
+we turn our attention to the related perfect advice setting, parameterized with
+a length $b\geq 0$, in which all active processes in a given execution are
+provided the best possible $b$ bits of information about their network. We
+provide tight bounds on the speed-up possible with respect to $b$ for
+deterministic and randomized algorithms, with and without collision detection.
+These bounds provide a fundamental limit on the maximum power that can be
+provided by any predictive model with a bounded output size.",2105.12706v1
+2021-05-27,Balancing Static Vacuum Black Holes with Signed Masses in 4 and 5 Dimensions,"We construct a new set of asymptotically flat, static vacuum solutions to the
+Einstein equations in dimensions 4 and 5, which may be interpreted as a
+superposition of positive and negative mass black holes. The resulting
+spacetimes are axisymmetric in 4-dimensions and bi-axisymmetric in
+5-dimensions, and are regular away from the negative mass singularities, for
+instance conical singularities are absent along the axes. In 5-dimensions, the
+topologies of signed mass black holes used in the construction may be either
+spheres $S^3$ or rings $S^1 \times S^2$; in particular, the negative mass
+static black ring solution is introduced. A primary observation that
+facilitates the superposition is the fact that, in Weyl-Papapetrou coordinates,
+negative mass singularities arise as overlapping singular support for a
+particular type of Green's function. Furthermore, a careful analysis of conical
+singularities along axes is performed, and formulas are obtained for their
+propagation across horizons, negative mass singularities, and corners. The
+methods are robust, and may be used to construct a multitude of further
+examples. Lastly, we show that balancing does not occur between any two signed
+mass black holes of the type studied here in 4 dimensions, while in 5
+dimensions two-body balancing is possible.",2105.13260v2
+2021-06-11,Inference for treatment-specific survival curves using machine learning,"In the absence of data from a randomized trial, researchers often aim to use
+observational data to draw causal inference about the effect of a treatment on
+a time-to-event outcome. In this context, interest often focuses on the
+treatment-specific survival curves; that is, the survival curves were the
+entire population under study to be assigned to receive the treatment or not.
+Under certain causal conditions, including that all confounders of the
+treatment-outcome relationship are observed, the treatment-specific survival
+can be identified with a covariate-adjusted survival function. Several
+estimators of this function have been proposed, including estimators based on
+outcome regression, inverse probability weighting, and doubly robust
+estimators. In this article, we propose a new cross-fitted doubly-robust
+estimator that incorporates data-adaptive (e.g. machine learning) estimators of
+the conditional survival functions. We establish conditions on the nuisance
+estimators under which our estimator is consistent and asymptotically linear,
+both pointwise and uniformly in time. We also propose a novel ensemble learner
+for combining multiple candidate estimators of the conditional survival
+estimators. Notably, our methods and results accommodate events occurring in
+discrete or continuous time (or both). We investigate the practical performance
+of our methods using numerical studies and an application to the effect of a
+surgical treatment to prevent metastases of parotid carcinoma on mortality.",2106.06602v1
+2021-06-10,Hard Choices in Artificial Intelligence,"As AI systems are integrated into high stakes social domains, researchers now
+examine how to design and operate them in a safe and ethical manner. However,
+the criteria for identifying and diagnosing safety risks in complex social
+contexts remain unclear and contested. In this paper, we examine the vagueness
+in debates about the safety and ethical behavior of AI systems. We show how
+this vagueness cannot be resolved through mathematical formalism alone, instead
+requiring deliberation about the politics of development as well as the context
+of deployment. Drawing from a new sociotechnical lexicon, we redefine vagueness
+in terms of distinct design challenges at key stages in AI system development.
+The resulting framework of Hard Choices in Artificial Intelligence (HCAI)
+empowers developers by 1) identifying points of overlap between design
+decisions and major sociotechnical challenges; 2) motivating the creation of
+stakeholder feedback channels so that safety issues can be exhaustively
+addressed. As such, HCAI contributes to a timely debate about the status of AI
+development in democratic societies, arguing that deliberation should be the
+goal of AI Safety, not just the procedure by which it is ensured.",2106.11022v1
+2021-06-30,A long-period substellar object exhibiting a single transit in Kepler,"We report the detection of a single transit-like signal in the Kepler data of
+the slightly evolved F star KIC4918810. The transit duration is ~45 hours, and
+while the orbital period ($P\sim10$ years) is not well constrained, it is one
+of the longest among companions known to transit. We calculate the size of the
+transiting object to be $R_P = 0.910$ $R_J$. Objects of this size vary by
+orders of magnitude in their densities, encompassing masses between that of
+Saturn ($0.3$ $M_J$) and stars above the hydrogen-burning limit (~80 $M_J$).
+Radial-velocity observations reveal that the companion is unlikely to be a
+star. The mass posterior is bimodal, indicating a mass of either ~0.24 $M_J$ or
+~26 $M_J$. Continued spectroscopic monitoring should either constrain the mass
+to be planetary or detect the orbital motion, the latter of which would yield a
+benchmark long-period brown dwarf with a measured mass, radius, and age.",2107.00027v1
+2021-08-03,Comparative study of magnetic properties of Mn$^{3+}$ magnetic clusters in GaN using classical and quantum mechanical approach,"Currently, simulations of many-body quantum systems are known to be
+computationally too demanding to be solved on classical computers. The main
+problem is that the computation time and memory necessary for performing the
+calculations usually grow exponentially with the number of particles $N$. An
+efficient approach to simulate many-body quantum systems is the use of
+classical approximation. However, it is known that at least at low
+temperatures, the allowed spin fluctuations in this approach are overestimated
+what results in enhanced thermal fluctuations. It is therefore timely and
+important to assess the validity of the classical approximation. To this end,
+in this work, we compare the results of numerical calculations of small
+Mn$^{3+}$ magnetic clusters in GaN, where the Mn spins are treated classically
+with those where they are treated quantum-mechanically (crystal field model).
+In the first case, we solve the Landau-Lifshitz-Gilbert (LLG) equation that
+describes the precessional dynamics of spins represented by classical vectors.
+On the other hand, in the crystal field model, the state of Mn$^{3+}$ ion
+($d^4$ configuration with $S=2$, $L=2$) is characterized by the set of orbital
+and spin quantum numbers $|m_s,m_L>$. Particular attention is paid to use
+numerical parameters that ensure the same single ion magnetic anisotropy in
+both classical and quantum approximation. Finally, a detailed comparative study
+of magnetization $\mathbf{M}(\mathbf{H}, T)$ as a function of the magnetic
+field $\mathbf{H}$, temperature $T$, number of ions in a given cluster $N$ and
+the strength of super-exchange interaction $J$, obtained from both approaches
+will be presented.",2108.01474v1
+2021-08-06,Performance trade-offs in cyber-physical control applications with multi-connectivity,"Modern communication devices are often equipped with multiple wireless
+communication interfaces with diverse characteristics. This enables exploiting
+a form of multi-connectivity known as interface diversity to provide path
+diversity with multiple communication interfaces. Interface diversity helps to
+combat the problems suffered by single-interface systems due to error bursts in
+the link, which are a consequence of temporal correlation in the wireless
+channel. The length of an error burst is an essential performance indicator for
+cyber-physical control applications with periodic traffic, as these define the
+period in which the control link is unavailable. However, the available
+interfaces must be correctly orchestrated to achieve an adequate trade-off
+between latency, reliability, and energy consumption. This work investigates
+how the packet error statistics from different interfaces impacts the overall
+latency-reliability characteristics and explores mechanisms to derive adequate
+interface diversity policies. For this, we model the optimization problem as a
+partially observable Markov Decision Process (POMDP), where the state of each
+interface is determined by a Gilbert-Elliott model whose parameters are
+estimated based on experimental measurement traces from LTE and Wi-Fi. Our
+results show that the POMDP approach provides an all-round adaptable solution,
+whose performance is only 0.1% below the absolute upper bound, dictated by the
+optimal policy under the impractical assumption of full observability.",2108.03035v1
+2021-08-16,$Q$-ary non-overlapping codes: a generating function approach,"Non-overlapping codes are a set of codewords in $\bigcup_{n \ge 2}
+\mathbb{Z}_q^n$, where $\mathbb{Z}_q = \{0,1,\dots,q-1\}$, such that, the
+prefix of each codeword is not a suffix of any codeword in the set, including
+itself; and for variable-length codes, a codeword does not contain any other
+codeword as a subword. In this paper, we investigate a generic method to
+generalize binary codes to $q$-ary for $q > 2$, and analyze this generalization
+on the two constructions given by Levenshtein (also by Gilbert; Chee, Kiah,
+Purkayastha, and Wang) and Bilotta, respectively. The generalization on the
+former construction gives large non-expandable fixed-length non-overlapping
+codes whose size can be explicitly determined; the generalization on the later
+construction is the first attempt to generate $q$-ary variable-length
+non-overlapping codes. More importantly, this generic method allows us to
+utilize the generating function approach to analyze the cardinality of the
+underlying $q$-ary non-overlapping codes. The generating function approach not
+only enables us to derive new results, e.g., recurrence relations on their
+cardinalities, new combinatorial interpretations for the constructions, and the
+limit superior of their cardinalities for some special cases, but also greatly
+simplifies the arguments for these results. Furthermore, we give an exact
+formula for the number of fixed-length words that do not contain the codewords
+in a variable-length non-overlapping code as subwords. This thereby solves an
+open problem by Bilotta and induces a recursive upper bound on the maximum size
+of variable-length non-overlapping codes.",2108.06934v1
+2021-08-17,Searching For or Reviewing Evidence Improves Crowdworkers' Misinformation Judgments and Reduces Partisan Bias,"Can crowd workers be trusted to judge whether news-like articles circulating
+on the Internet are misleading, or does partisanship and inexperience get in
+the way? And can the task be structured in a way that reduces partisanship? We
+assembled pools of both liberal and conservative crowd raters and tested three
+ways of asking them to make judgments about 374 articles. In a no research
+condition, they were just asked to view the article and then render a judgment.
+In an individual research condition, they were also asked to search for
+corroborating evidence and provide a link to the best evidence they found. In a
+collective research condition, they were not asked to search, but instead to
+review links collected from workers in the individual research condition. Both
+research conditions reduced partisan disagreement in judgments. The individual
+research condition was most effective at producing alignment with journalists'
+assessments. In this condition, the judgments of a panel of sixteen or more
+crowd workers were better than that of a panel of three expert journalists, as
+measured by alignment with a held out journalist's ratings.",2108.07898v3
+2021-08-23,The Multiverse: Logical Modularity for Proof Assistants,"Proof assistants play a dual role as programming languages and logical
+systems. As programming languages, proof assistants offer standard modularity
+mechanisms such as first-class functions, type polymorphism and modules. As
+logical systems, however, modularity is lacking, and understandably so:
+incompatible reasoning principles -- such as univalence and uniqueness of
+identity proofs -- can indirectly lead to logical inconsistency when used in a
+given development, even when they appear to be confined to different modules.
+The lack of logical modularity in proof assistants also hinders the adoption of
+richer programming constructs, such as effects. We propose the multiverse, a
+general type-theoretic approach to endow proof assistants with logical
+modularity. The multiverse consists of multiple universe hierarchies that
+statically describe the reasoning principles and effects available to define a
+term at a given type. We identify sufficient conditions for this structuring to
+modularly ensure that incompatible principles do not interfere, and to locally
+restrict the power of dependent elimination when necessary. This extensible
+approach generalizes the ad-hoc treatment of the sort of propositions in the
+Coq proof assistant. We illustrate the power of the multiverse by describing
+the inclusion of Coq-style propositions, the strict propositions of Gilbert et
+al., the exceptional type theory of P\'edrot and Tabareau, and general
+axiomatic extensions of the logic.",2108.10259v1
+2021-08-27,Distributed Control and Optimization of DC Microgrids: A Port-Hamiltonian Approach,"This article proposes a distributed secondary control scheme that drives a dc
+microgrid to an equilibrium point where the generators share optimal currents,
+and their voltages have a weighted average of nominal value. The scheme does
+not rely on the electric system topology nor its specifications; it guarantees
+plug-and-play design and functionality of the generators. First, the
+incremental model of the microgrid system with constant impedance, current, and
+power devices is shown to admit a port-Hamiltonian (pH) representation, and its
+passive output is determined. The economic dispatch problem is then solved by
+the Lagrange multipliers method; the Karush-Kuhn-Tucker conditions and weighted
+average formation of voltages are then formulated as the control objectives. We
+propose a control scheme that is based on the Control by Interconnection design
+philosophy, where the consensus-based controller is viewed as a virtual pH
+system to be interconnected with the physical one. We prove the regional
+asymptotic stability of the closed-loop system using Lyapunov and LaSalle
+theorems. Equilibrium analysis is also conducted based on the concepts of graph
+theory and economic dispatch. Finally, the effectiveness of the presented
+scheme for different case studies is validated with a test microgrid system,
+simulated in both MATLAB/Simulink and OPAL-RT environments.",2108.12341v1
+2021-10-23,Bootstrap percolation in random geometric graphs,"Following Bradonji\'c and Saniee, we study a model of bootstrap percolation
+on the Gilbert random geometric graph on the $2$-dimensional torus. In this
+model, the expected number of vertices of the graph is $n$, and the expected
+degree of a vertex is $a\log n$ for some fixed $a>1$. Each vertex is added with
+probability $p$ to a set $A_0$ of initially infected vertices. Vertices
+subsequently become infected if they have at least $ \theta a \log n $ infected
+neighbours. Here $p, \theta \in [0,1]$ are taken to be fixed constants.
+  We show that if $\theta < (1+p)/2$, then a sufficiently large local outbreak
+leads with high probability to the infection spreading globally, with all but
+$o(n)$ vertices eventually becoming infected. On the other hand, for $ \theta >
+(1+p)/2$, even if one adversarially infects every vertex inside a ball of
+radius $O(\sqrt{\log n} )$, with high probability the infection will spread to
+only $o(n)$ vertices beyond those that were initially infected.
+  In addition we give some bounds on the $(a, p, \theta)$ regions ensuring the
+emergence of large local outbreaks or the existence of islands of vertices that
+never become infected. We also give a complete picture of the (surprisingly
+complex) behaviour of the analogous $1$-dimensional bootstrap percolation model
+on the circle. Finally we raise a number of problems, and in particular make a
+conjecture on an `almost no percolation or almost full percolation' dichotomy
+which may be of independent interest.",2110.12166v1
+2021-11-02,Orbital Dynamics and the Evolution of Planetary Habitability in the AU Mic System,"The diversity of planetary systems that have been discovered are revealing
+the plethora of possible architectures, providing insights into planet
+formation and evolution. They also increase our understanding of system
+parameters that may affect planetary habitability, and how such conditions are
+influenced by initial conditions. The AU~Mic system is unique among known
+planetary systems in that it is a nearby, young, multi-planet transiting
+system. Such a young and well characterized system provides an opportunity to
+study orbital dynamical and habitability studies for planets in the very early
+stages of their evolution. Here, we calculate the evolution of the Habitable
+Zone of the system through time, including the pre-main sequence phase that the
+system currently resides in. We discuss the planetary atmospheric processes
+occurring for an Earth-mass planet during this transitionary period, and
+provide calculations of the climate state convergence age for both volatile
+rich and poor initial conditions. We present results of an orbital dynamical
+analysis of the AU~Mic system that demonstrate the rapid eccentricity evolution
+of the known planets, and show that terrestrial planets within the Habitable
+Zone of the system can retain long-term stability. Finally, we discuss
+follow-up observation prospects, detectability of possible Habitable Zone
+planets, and how the AU Mic system may be used as a template for studies of
+planetary habitability evolution.",2111.01816v1
+2021-11-17,Privacy-preserving Federated Learning for Residential Short Term Load Forecasting,"With high levels of intermittent power generation and dynamic demand
+patterns, accurate forecasts for residential loads have become essential. Smart
+meters can play an important role when making these forecasts as they provide
+detailed load data. However, using smart meter data for load forecasting is
+challenging due to data privacy requirements. This paper investigates how these
+requirements can be addressed through a combination of federated learning and
+privacy preserving techniques such as differential privacy and secure
+aggregation. For our analysis, we employ a large set of residential load data
+and simulate how different federated learning models and privacy preserving
+techniques affect performance and privacy. Our simulations reveal that
+combining federated learning and privacy preserving techniques can secure both
+high forecasting accuracy and near-complete privacy. Specifically, we find that
+such combinations enable a high level of information sharing while ensuring
+privacy of both the processed load data and forecasting models. Moreover, we
+identify and discuss challenges of applying federated learning, differential
+privacy and secure aggregation for residential short-term load forecasting.",2111.09248v4
+2021-11-30,The AiiDA-Spirit plugin for automated spin-dynamics simulations and multi-scale modelling based on first-principles calculations,"Landau-Lifshitz-Gilbert (LLG) spin-dynamics calculations based on the
+extended Heisenberg Hamiltonian is an important tool in computational materials
+science involving magnetic materials. LLG simulations allow to bridge the gap
+from expensive quantum mechanical calculations with small unit cells to large
+supercells where the collective behavior of millions of spins can be studied.
+In this work we present the AiiDA-Spirit plugin that connects the spin-dynamics
+code Spirit to the AiiDA framework. AiiDA provides a Python interface that
+facilitates performing high-throughput calculations while automatically
+augmenting the calculations with metadata describing the data provenance
+between calculations in a directed acyclic graph. The AiiDA-Spirit interface
+thus provides an easy way for high-throughput spin-dynamics calculations. The
+interface to the AiiDA infrastructure furthermore has the advantage that input
+parameters for the extended Heisenberg model can be extracted from
+high-throughput first-principles calculations including a proper treatment of
+the data provenance that ensures reproducibility of the calculation results in
+accordance to the FAIR principles. We describe the layout of the AiiDA-Spirit
+plugin and demonstrate its capabilities using selected examples for LLG
+spin-dynamics and Monte Carlo calculations. Furthermore, the integration with
+first-principles calculations through AiiDA is demonstrated at the example of
+$\gamma$-Fe, where the complex spin-spiral ground state is investigated.",2111.15229v1
+2021-12-10,A Framework for Fairness: A Systematic Review of Existing Fair AI Solutions,"In a world of daily emerging scientific inquisition and discovery, the
+prolific launch of machine learning across industries comes to little surprise
+for those familiar with the potential of ML. Neither so should the congruent
+expansion of ethics-focused research that emerged as a response to issues of
+bias and unfairness that stemmed from those very same applications. Fairness
+research, which focuses on techniques to combat algorithmic bias, is now more
+supported than ever before. A large portion of fairness research has gone to
+producing tools that machine learning practitioners can use to audit for bias
+while designing their algorithms. Nonetheless, there is a lack of application
+of these fairness solutions in practice. This systematic review provides an
+in-depth summary of the algorithmic bias issues that have been defined and the
+fairness solution space that has been proposed. Moreover, this review provides
+an in-depth breakdown of the caveats to the solution space that have arisen
+since their release and a taxonomy of needs that have been proposed by machine
+learning practitioners, fairness researchers, and institutional stakeholders.
+These needs have been organized and addressed to the parties most influential
+to their implementation, which includes fairness researchers, organizations
+that produce ML algorithms, and the machine learning practitioners themselves.
+These findings can be used in the future to bridge the gap between
+practitioners and fairness experts and inform the creation of usable fair ML
+toolkits.",2112.05700v1
+2021-12-12,Effect of Topological Non-hexagonal Rings and Stone Wale Defects on the Vibrational Response of Single and Multi-Layer Ion Irradiated Graphene,"Present study explores the observation of topological non-hexagonal rings
+(NHR) and Stone Wale (SW) defects by Raman experiments in both single (SLG) and
+multi-layer graphene (MLG) after they are irradiated with 100- 300 eV Ar ions.
+Although predicted by theoretical studies, here it is experimentally shown for
+the first time that graphene SW/NHR defects have a signature in Raman. Broad
+bandwidth of the pertinent Raman features suggests the presence of more than
+one SW/NHR defect mode, in agreement with the DFT studies. Variations in the
+SW/NHR related Raman mode intensities demonstrate the annihilation of these
+topological defects at higher energies. Behavior of Raman allowed G and 2D
+excitations, as well as the disorder-activated D, D' and G* lines, has also
+been investigated in SLG and MLG. These indicate an evolution of defects in
+graphene with ion irradiation, as well as presence of a transition state beyond
+which the Raman modes are dominated by a rise in sp3 content. Correlation of
+these aspects with the SW/NHR Raman provide significant insight into ion
+induced evolution of graphene. The direct observation of SW/NHR defects by
+Raman spectroscopy could be important in promoting exploration of rich
+topological aspects of Graphene in various fields.",2112.06294v1
+2021-12-16,Minimal blowing pressure allowing periodic oscillations in a model of bass brass instruments,"In this study, an acoustic resonator -- a bass brass instrument -- with
+multiple resonances coupled to an exciter -- the player's lips -- with one
+resonance is modelled by a multidimensional dynamical system, and studied using
+a continuation and bifurcation software. Bifurcation diagrams are explored with
+respect to the blowing pressure, in particular with focus on the minimal
+blowing pressure allowing stable periodic oscillations and the associated
+frequency.The behaviour of the instrument is first studied close to a (non
+oscillating) equilibrium using linear stability analysis. This allows to
+determine the conditions at which an equilibrium destabilises and as such where
+oscillating regimes can emerge (corresponding to a sound production). This
+approach is useful to characterise the ease of playing of a brass instrument,
+which is assumed here to be related -- as a first approximation -- to the
+linear threshold pressure. In particular, the lower the threshold pressure, the
+lower the physical effort the player has to make to play a note [Campbell et
+al., 2021].Cases are highlighted where periodic solutions in the bifurcation
+diagrams are reached for blowing pressures below the value given by the linear
+stability analysis. Thus, bifurcation diagrams allow a more in-depth analysis.
+Particular attention is devoted to the first playing regime of bass brass
+instruments (the pedal note and the ghost note of a tuba in particular), whose
+behaviour qualitatively differs from a trombone to a euphonium for instance.",2112.08751v2
+2021-12-20,"Refined modelling of the radio SZ signal: kinematic terms, relativistic temperature corrections and anisotropies in the radio background","A significant cosmological radio background will inevitably lead to a radio
+Sunyaev-Zeldovich (SZ) effect. In the simplest limit, the combined signal from
+the scattered radio and cosmic microwave background exhibits a null at around
+$\nu \simeq 735$ MHz. Here, we show that kinematic and relativistic temperature
+corrections to this radio SZ signal are easily calculable. We treat both the
+cluster and observer motion, and the scattering of anisotropies in the radio
+background, highlighting how the spectrum of the radio SZ effect is affected in
+each case. Although relativistic temperature corrections only enter at the
+level of a few percent, our expressions allow high-precision modelling of these
+terms. By measuring the SZ signal around the radio null, one is in principle
+able to place constraints on the properties of a cosmological radio background.
+A combination with standard SZ measurements from large cluster samples could
+provide a promising avenue towards breaking degeneracies between different
+contributions. Stacking analyses can reduce the effect of kinematic corrections
+and dipolar anisotropies in the radio background, thereby providing a way to
+constrain the redshift dependence of the average radio background. Our
+qualitative discussion is meant to give an analytic understanding of the
+various effects and also motivate further studies with the aim to obtain
+quantitative forecasts of their observability. At this stage, a detection of
+the corrections seems rather futuristic, but the advent of large SZ and X-ray
+cluster samples could drastically improve our ability to disentangle various
+effects.",2112.10666v2
+2021-12-22,Conductive and convective heat transfer in inductive heating of subsea buried pipelines,"Inductive heating with high-voltage cables reduces the risk of hydrate
+formation by raising the temperature of the production fluid in pipelines.
+Heating the pipeline results in losing a certain fraction of the heat to the
+surrounding soil through conduction or convection-dominated flow through the
+soil. However, the amount of heat lost in conduction versus convection and the
+transition from conduction to convection-dominated heat loss remains unknown.
+Soil permeability, temperature gradient between cable and mudline, and burial
+depth influence the mode of heat transfer and the amount of heat lost. We study
+the dominant mode of heat transfer in pipelines with inductive heating using 2D
+Finite Difference analysis under different soil and environmental conditions.
+Low permeability soils primarily exhibit conductive heat transfer, thus losing
+minimum heat to the surrounding soil. In contrast, convective flow drives a
+significant fraction of the heat away from the pipeline and towards the ground
+surface for highly permeable soils, barely heating the fluid in the pipe. We
+identify a critical Rayleigh-Darcy number of 1 as the controlling value
+separating conduction and convection-dominated heat transfer. An increase in
+burial depth deteriorates the heating efficiency in convection-dominated high
+permeability soils, while it remains unaffected in conduction-dominated low
+permeability soils.",2112.11826v1
+2021-12-28,"Phonon, Electron, and Magnon Excitations in Antiferromagnetic L1$_{0}$-type MnPt","Antiferromagnetic L1$_{0}$-type MnPt is a material with relatively simple
+crystal and magnetic structure, recently attracting interest due to its high
+N{\'{e}}el temperature and wide usage as a pinning layer in magnetic devices.
+While it is experimentally well characterized, the theoretical understanding is
+much less developed, in part due to the challenging accuracy requirements
+dictated by the small underlying energy scales that govern magnetic ordering in
+antiferromagnetic metals. In this work, we use density functional theory, the
+Korringa-Kohn-Rostoker formalism, and a Heisenberg model to establish a
+comprehensive theoretical description of antiferromagnetic L1$_{0}$-type MnPt,
+along with accuracy limits, by thoroughly comparing to available literature
+data. Our simulations show that the contribution of the magnetic dipole
+interaction to the magnetocrystalline anisotropy energy of $K_{1}$=1.07$\times
+10^{6}$\,J/m$^3$ is comparable in magnitude to the spin-orbit contribution.
+Using our result for the magnetic susceptibility of $5.25\times10^{-4}$, a
+lowest magnon frequency of about 2.02\,THz is predicted, confirming THz spin
+dynamics in this material. From our data for electron, phonon, and magnon
+dispersion we compute the individual contributions to the total heat capacity
+and show that the dominant term at or above 2\,K arises from phonons. From the
+Landau-Lifshitz-Gilbert equation, we compute a N\'{e}el temperature of
+990--1070 K. Finally, we quantify the magnitude of the magneto-optical Kerr
+effect generated by applying an external magnetic field. Our results provide
+insight into the underlying physics, which is critical for a deep understanding
+of fundamental limits of the time scale of spin dynamics, stability of the
+magnetic ordering, and the possibility of magneto-optical detection of
+collective spin motion.",2112.13954v1
+2022-01-22,"Estimation and Hypothesis Testing of Strain-Specific Vaccine Efficacy with Missing Strain Types, with Applications to a COVID-19 Vaccine Trial","Statistical methods are developed for analysis of clinical and virus genetics
+data from phase 3 randomized, placebo-controlled trials of vaccines against
+novel coronavirus COVID-19. Vaccine efficacy (VE) of a vaccine to prevent
+COVID-19 caused by one of finitely many genetic strains of SARS-CoV-2 may vary
+by strain. The problem of assessing differential VE by viral genetics can be
+formulated under a competing risks model where the endpoint is virologically
+confirmed COVID-19 and the cause-of-failure is the infecting SARS-CoV-2
+genotype. Strain-specific VE is defined as one minus the cause-specific hazard
+ratio (vaccine/placebo). For the COVID-19 VE trials, the time to COVID-19 is
+right-censored, and a substantial percentage of failure cases are missing the
+infecting virus genotype. We develop estimation and hypothesis testing
+procedures for strain-specific VE when the failure time is subject to right
+censoring and the cause-of-failure is subject to missingness, focusing on $J
+\ge 2$ discrete categorical unordered or ordered virus genotypes. The
+stratified Cox proportional hazards model is used to relate the cause-specific
+outcomes to explanatory variables. The inverse probability weighted
+complete-case (IPW) estimator and the augmented inverse probability weighted
+complete-case (AIPW) estimator are investigated. Hypothesis tests are developed
+to assess whether the vaccine provides at least a specified level of efficacy
+against some viral genotypes and whether VE varies across genotypes, adjusting
+for covariates. The finite-sample properties of the proposed tests are studied
+through simulations and are shown to have good performances. In preparation for
+the real data analyses, the developed methods are applied to a pseudo dataset
+mimicking the Moderna COVE trial.",2201.08946v1
+2022-01-30,OverChain: Building a robust overlay with a blockchain,"Blockchains use peer-to-peer networks for disseminating information among
+peers, but these networks currently do not have any provable guarantees for
+desirable properties such as Byzantine fault tolerance, good connectivity and
+small diameter. This is not just a theoretical problem, as recent works have
+exploited unsafe peer connection policies and weak network synchronization to
+mount partitioning attacks on Bitcoin. Cryptocurrency blockchains are safety
+critical systems, so we need principled algorithms to maintain their networks.
+  Our key insight is that we can leverage the blockchain itself to share
+information among the peers, and thus simplify the network maintenance process.
+Given that the peers have restricted computational resources, and at most a
+constant fraction of them are Byzantine, we provide communication-efficient
+protocols to maintain a hypercubic network for blockchains, where peers can
+join and leave over time. Interestingly, we discover that our design can
+\emph{recover} from substantial adversarial failures. Moreover, these
+properties hold despite significant churn.
+  A key contribution is a secure mechanism for joining the network that uses
+the blockchain to help new peers to contact existing peers. Furthermore, by
+examining how peers join the network, i.e., the ""bootstrapping service,"" we
+give a lower bound showing that (within log factors) our network tolerates the
+maximum churn rate possible. In fact, we can give a lower bound on churn for
+any fully distributed service that requires connectivity.",2201.12809v1
+2022-02-04,Three-axis torque investigation of interfacial exchange coupling in a NiFe/CoO bilayer micromagnetic disk,"Micrometer diameter bilayers of NiFe (permalloy, Py) and cobalt oxide (CoO)
+deposited on nanomechanical resonators were used to investigate exchange bias
+effects. The mechanical compliances of two resonator axes were enhanced by
+severing one torsion arm, resulting in a unique three-axis resonator that
+responds resonantly to torques generated by a three-axis RF field. Our
+technique permits simultaneous measurement of three orthogonal torque
+components. Measurements of the anisotropies associated with interfacial
+exchange coupling effects have been made. At cryogenic temperatures,
+observations of shifted linear hysteresis loops confirmed the presence of
+exchange bias from the Py/CoO interface. An in-plane rotating DC bias field was
+used to probe in-plane anisotropies through the out-of-plane torque. Training
+effects in the rotational hysteresis data were observed and showed that
+features due to interfacial coupling did not diminish irrespective of
+substantial training of the unidirectional anisotropy. The data from the
+rotational hysteresis loops were fit with parameters from a macrospin solution
+to the Landau-Lifshitz-Gilbert equation. Each parameter of the exchange bias
+model accounts for specific features of the rotational loop.",2202.02386v1
+2022-02-11,"Choices, Risks, and Reward Reports: Charting Public Policy for Reinforcement Learning Systems","In the long term, reinforcement learning (RL) is considered by many AI
+theorists to be the most promising path to artificial general intelligence.
+This places RL practitioners in a position to design systems that have never
+existed before and lack prior documentation in law and policy. Public agencies
+could intervene on complex dynamics that were previously too opaque to
+deliberate about, and long-held policy ambitions would finally be made
+tractable. In this whitepaper we illustrate this potential and how it might be
+technically enacted in the domains of energy infrastructure, social media
+recommender systems, and transportation. Alongside these unprecedented
+interventions come new forms of risk that exacerbate the harms already
+generated by standard machine learning tools. We correspondingly present a new
+typology of risks arising from RL design choices, falling under four
+categories: scoping the horizon, defining rewards, pruning information, and
+training multiple agents. Rather than allowing RL systems to unilaterally
+reshape human domains, policymakers need new mechanisms for the rule of reason,
+foreseeability, and interoperability that match the risks these systems pose.
+We argue that criteria for these choices may be drawn from emerging subfields
+within antitrust, tort, and administrative law. It will then be possible for
+courts, federal and state agencies, and non-governmental organizations to play
+more active roles in RL specification and evaluation. Building on the ""model
+cards"" and ""datasheets"" frameworks proposed by Mitchell et al. and Gebru et
+al., we argue the need for Reward Reports for AI systems. Reward Reports are
+living documents for proposed RL deployments that demarcate design choices.",2202.05716v1
+2022-02-22,Entropy-driven order in an array of nanomagnets,"Long-range ordering is typically associated with a decrease in entropy. Yet,
+it can also be driven by increasing entropy in certain special cases. We
+demonstrate that artificial spin ice arrays of single-domain nanomagnets can be
+designed to produce entropy-driven order. We focus on the tetris artificial
+spin ice structure, a highly frustrated array geometry with a zero-point Pauli
+entropy, which is formed by selectively creating regular vacancies on the
+canonical square ice lattice. We probe thermally active tetris artificial spin
+ice both experimentally and through simulations, measuring the magnetic moments
+of the individual nanomagnets. We find two-dimensional magnetic ordering in one
+subset of these moments, which we demonstrate to be induced by disorder (i.e.,
+increased entropy) in another subset of the moments. In contrast with other
+entropy-driven systems, the discrete degrees of freedom in tetris artificial
+spin ice are binary and are both designable and directly observable at the
+microscale, and the entropy of the system is precisely calculable in
+simulations. This example, in which the system's interactions and ground state
+entropy are well-defined, expands the experimental landscape for the study of
+entropy-driven ordering.",2202.11010v1
+2022-03-30,Kinematics and Metallicity of Red Giant Branch Stars in the Northeast Shelf of M31,"We obtained Keck/DEIMOS spectra of 556 individual red giant branch stars in 4
+spectroscopic fields spanning $13-31$ projected kpc along the Northeast (NE)
+shelf of M31. We present the first detection of a complete wedge pattern in the
+space of projected M31-centric radial distance versus line-of-sight velocity
+for this feature, which includes the returning stream component of the shelf.
+This wedge pattern agrees with expectations of a tidal shell formed in a radial
+merger and provides strong evidence in favor of predictions of Giant Stellar
+Stream (GSS) formation models in which the NE shelf originates from the second
+orbital wrap of the tidal debris. The observed concentric wedge patterns of the
+NE, West (W), and Southeast (SE) shelves corroborate this interpretation
+independently of the models. We do not detect a kinematical signature in the NE
+shelf region corresponding to an intact progenitor core, favoring GSS formation
+models in which the progenitor is completely disrupted. The shelf's photometric
+metallicity distribution implies that it is dominated by tidal material, as
+opposed to the phase-mixed stellar halo or the disk. The metallicity
+distribution ([Fe/H]$_{\rm phot}$ = $-0.42$ $\pm$ $0.01$) also matches the GSS,
+and consequently the W and SE shelves, further supporting a direct physical
+association between the tidal features.",2203.16675v1
+2022-04-06,Stability and Safety through Event-Triggered Intermittent Control with Application to Spacecraft Orbit Stabilization,"In systems where the ability to actuate is a scarce resource, e.g.,
+spacecrafts, it is desirable to only apply a given controller in an
+intermittent manner--with periods where the controller is on and periods where
+it is off. Motivated by the event-triggered control paradigm, where
+state-dependent triggers are utilized in a sample-and-hold context, we
+generalize this concept to include state triggers where the controller is off
+thereby creating a framework for intermittent control. Our approach utilizes
+certificates--either Lyapunov or barrier functions--to design intermittent
+trigger laws that guarantee stability or safety; the controller is turned on
+for the period for which is beneficial with regard to the certificate, and
+turned off until a performance threshold is reached. The main result of this
+paper is that the intermittent controller scheme guarantees (set) stability
+when Lyapunov functions are utilized, and safety (forward set invariance) in
+the setting of barrier functions. As a result, our trigger designs can leverage
+the intermittent nature of the actuator, and at the same time, achieve the task
+of stabilization or safety. We further demonstrate the application and benefits
+of intermittent control in the context of the spacecraft orbit stabilization
+problem.",2204.03110v1
+2022-04-19,Higher-order modulations in the skyrmion-lattice phase of Cu$_2$OSeO$_3$,"Using small angle neutron scattering, we have investigated higher-order peaks
+in the skyrmion-lattice phase of Cu$_2$OSeO$_3$, in which two different
+skyrmion lattices, SkX1 and SkX2, are known to form. For each skyrmion-lattice
+phase, we observed two sets of symmetrically inequivalent peaks at the
+higher-order-reflection positions with the indices $(110)$ and $(200)$. Under
+the condition where the SkX1 and SkX2 coexist, we confirmed the absence of the
+scattering at $\mathbf{Q}$ positions combining reflections from the two phases,
+indicating a significantly weak double-scattering component. Detailed analysis
+of the peak profile, as well as the temperature and magnetic-field dependence
+of the peak intensity, also supports the intrinsic higher-order modulation
+rather than the parasitic double scattering. The two higher-order modulations
+show contrasting magnetic-field dependence; the former $(110)$ increases as the
+field is increased, whereas the latter $(200)$ decreases. This indicates that,
+in Cu$_2$OSeO$_3$, skyrmions are weakly distorted, and the distortion is
+field-dependent in a way that the dominant higher-order modulation switches
+from $(110)$ to $(200)$ under field. Monte Carlo simulations under sweeping
+external magnetic field qualitatively reproduce the observed magnetic-field
+dependence, and suggests that the higher-order modulations correspond to the
+superlattices of weak swirlings appearing in the middle of the original
+triangular-latticed skyrmions.",2204.08614v1
+2022-04-19,Emu: A Case Study for TDI-like Imaging for Infrared Observation from Space,"A wide-field zenith-looking telescope operating in a mode similar to
+Time-Delay-Integration (TDI) or drift scan imaging can perform an infrared sky
+survey without active pointing control but it requires a high-speed, low-noise
+infrared detector. Operating from a hosted payload platform on the
+International Space Station (ISS), the Emu space telescope employs the
+paradigm-changing properties of the Leonardo SAPHIRA electron avalanche
+photodiode array to provide powerful new observations of cool stars at the
+critical water absorption wavelength (1.4 $\mu$m) largely inaccessible to
+ground-based telescopes due to the Earth's own atmosphere. Cool stars,
+especially those of spectral-type M, are important probes across contemporary
+astrophysics, from the formation history of the Galaxy to the formation of
+rocky exoplanets. Main sequence M-dwarf stars are the most abundant stars in
+the Galaxy and evolved M-giant stars are some of the most distant stars that
+can be individually observed. The Emu sky survey will deliver critical stellar
+properties of these cool stars by inferring oxygen abundances via measurement
+of the water absorption band strength at 1.4 $\mu$m. Here we present the
+TDI-like imaging capability of Emu mission, its science objectives, instrument
+details and simulation results.",2204.08713v2
+2022-05-05,Photon emissivity of the quark-gluon plasma: a lattice QCD analysis of the transverse channel,"We present results for the thermal photon emissivity of the quark-gluon
+plasma derived from spatially transverse vector correlators computed in lattice
+QCD at a temperature of 250 MeV. The analysis of the spectral functions,
+performed at fixed spatial momentum, is based on continuum-extrapolated
+correlators obtained with two flavours of dynamical Wilson fermions. We compare
+the next-to-leading order perturbative QCD correlators, as well as the ${\cal
+N}=4$ supersymmetric Yang-Mills correlators at infinite coupling, to the
+correlators from lattice QCD and find them to lie within $\sim10\%$ of each
+other. We then refine the comparison, performing it at the level of filtered
+spectral functions obtained model-independently via the Backus-Gilbert method.
+Motivated by these studies, for frequencies $\omega\lesssim2.5\,$GeV we use fit
+ans\""atze to the spectral functions that perform well when applied to mock data
+generated from the NLO QCD or from the strongly-coupled SYM spectral functions,
+while the high-frequency part, $\omega\gtrsim 2.5\,$GeV, is matched to NLO QCD.
+We compare our results for the photon emissivity to our previous analysis of a
+different vector channel at the same temperature. We obtain the most stringent
+constraint at photon momenta around $k\simeq0.8\,$GeV, for which we find a
+differential photon emission rate per unit volume of $d\Gamma_\gamma/d^3k =
+(\alpha_{\rm em}/(\exp(k/T)-1))\times (2.2 \pm 0.8 ) \times 10^{-3}\,{\rm
+GeV}$.",2205.02821v1
+2022-05-17,"Highlighting relations between Wave-particle duality, Uncertainty principle, Phase space and Microstates","Wave-particle duality is often considered as the modern answer to the problem
+of the nature of light after more than 2000 years of questioning. It is also
+the answer given by quantum physics concerning the nature of matter particles
+and any other radiations. The main objective of this work is to analyze the
+relations that are existing between this concept of wave-particle duality, the
+uncertainty principle and the concepts of phase space and microstates
+considered in statistical mechanics. It is mainly highlighted that while the
+concepts of phase space and microstates were already introduced in classical
+physics before the discovery of the wave-particle duality, a correct
+understanding of them cannot be achieved without the use of the concept of
+quantum phase space and phase space representation of quantum mechanics which
+are directly related to the uncertainty principle. The possibility of using
+these concepts of quantum phase space and phase space representations of
+quantum mechanics to help in a deeper description of the wave-particle duality
+and in the study of some current issues related to foundational problems of
+quantum mechanics like quantum decoherence and the measurement problem is also
+discussed.",2205.08538v4
+2022-05-26,New Explicit Good Linear Sum-Rank-Metric Codes,"Sum-rank-metric codes have wide applications in universal error correction,
+multishot network coding, space-time coding and the construction of partial-MDS
+codes for repair in distributed storage. Fundamental properties of
+sum-rank-metric codes have been studied and some explicit or probabilistic
+constructions of good sum-rank-metric codes have been proposed. In this paper
+we give three simple constructions of explicit linear sum-rank-metric codes. In
+finite length regime, numerous larger linear sum-rank-metric codes with the
+same minimum sum-rank distances as the previous constructed codes can be
+derived from our constructions. For example several better linear
+sum-rank-metric codes over ${\bf F}_q$ with small block sizes and the matrix
+size $2 \times 2$ are constructed for $q=2, 3, 4$ by applying our construction
+to the presently known best linear codes. Asymptotically our constructed
+sum-rank-metric codes are close to the Gilbert-Varshamov-like bound on
+sum-rank-metric codes for some parameters. Finally we construct a linear MSRD
+code over an arbitrary finite field ${\bf F}_q$ with various square matrix
+sizes $n_1, n_2, \ldots, n_t$ satisfying $n_i \geq n_{i+1}^2+\cdots+n_t^2$ ,
+$i=1, 2, \ldots, t-1$, for any given minimum sum-rank distance. There is no
+restriction on the block lengths $t$ and parameters $N=n_1+\cdots+n_t$ of these
+linear MSRD codes from the sizes of the fields ${\bf F}_q$. \end{abstract}",2205.13087v8
+2022-06-17,Multi-scale Super-resolution Magnetic Resonance Spectroscopic Imaging with Adjustable Sharpness,"Magnetic Resonance Spectroscopic Imaging (MRSI) is a valuable tool for
+studying metabolic activities in the human body, but the current applications
+are limited to low spatial resolutions. The existing deep learning-based MRSI
+super-resolution methods require training a separate network for each upscaling
+factor, which is time-consuming and memory inefficient. We tackle this
+multi-scale super-resolution problem using a Filter Scaling strategy that
+modulates the convolution filters based on the upscaling factor, such that a
+single network can be used for various upscaling factors. Observing that each
+metabolite has distinct spatial characteristics, we also modulate the network
+based on the specific metabolite. Furthermore, our network is conditioned on
+the weight of adversarial loss so that the perceptual sharpness of the
+super-resolved metabolic maps can be adjusted within a single network. We
+incorporate these network conditionings using a novel Multi-Conditional Module.
+The experiments were carried out on a 1H-MRSI dataset from 15 high-grade glioma
+patients. Results indicate that the proposed network achieves the best
+performance among several multi-scale super-resolution methods and can provide
+super-resolved metabolic maps with adjustable sharpness.",2206.08984v1
+2022-06-20,How to Assess Trustworthy AI in Practice,"This report is a methodological reflection on
+Z-Inspection$^{\small{\circledR}}$. Z-Inspection$^{\small{\circledR}}$ is a
+holistic process used to evaluate the trustworthiness of AI-based technologies
+at different stages of the AI lifecycle. It focuses, in particular, on the
+identification and discussion of ethical issues and tensions through the
+elaboration of socio-technical scenarios. It uses the general European Union's
+High-Level Expert Group's (EU HLEG) guidelines for trustworthy AI. This report
+illustrates for both AI researchers and AI practitioners how the EU HLEG
+guidelines for trustworthy AI can be applied in practice. We share the lessons
+learned from conducting a series of independent assessments to evaluate the
+trustworthiness of AI systems in healthcare. We also share key recommendations
+and practical suggestions on how to ensure a rigorous trustworthy AI assessment
+throughout the life-cycle of an AI system.",2206.09887v2
+2022-06-23,LRPC codes with multiple syndromes: near ideal-size KEMs without ideals,"We introduce a new rank-based key encapsulation mechanism (KEM) with public
+key and ciphertext sizes around 3.5 Kbytes each, for 128 bits of security,
+without using ideal structures. Such structures allow to compress objects, but
+give reductions to specific problems whose security is potentially weaker than
+for unstructured problems. To the best of our knowledge, our scheme improves in
+size all the existing unstructured post-quantum lattice or code-based
+algorithms such as FrodoKEM or Classic McEliece. Our technique, whose
+efficiency relies on properties of rank metric, is to build upon existing Low
+Rank Parity Check (LRPC) code-based KEMs and to send multiple syndromes in one
+ciphertext, allowing to reduce the parameters and still obtain an acceptable
+decoding failure rate. Our system relies on the hardness of the Rank Support
+Learning problem, a well-known variant of the Rank Syndrome Decoding problem.
+The gain on parameters is enough to significantly close the gap between ideal
+and non-ideal constructions. It enables to choose an error weight close to the
+rank Gilbert-Varshamov bound, which is a relatively harder zone for algebraic
+attacks. We also give a version of our KEM that keeps an ideal structure and
+permits to roughly divide the bandwidth by two compared to previous versions of
+LRPC KEMs submitted to the NIST with a Decoding Failure Rate (DFR) of
+$2^{-128}$.",2206.11961v1
+2022-07-08,Rate-Optimal Streaming Codes Over the Three-Node Decode-And-Forward Relay Network,"In this paper, we study the three-node Decode-and-Forward (D&F) relay network
+subject to random and burst packet erasures. The source wishes to transmit an
+infinite stream of packets to the destination via the relay. The three-node D&F
+relay network is constrained by a decoding delay of T packets, i.e., the packet
+transmitted by the source at time i must be decoded by the destination by time
+i+T. For the individual channels from source to relay and relay to destination,
+we assume a delay-constrained sliding-window (DCSW) based packet-erasure model
+that can be viewed as a tractable approximation to the commonly-accepted
+Gilbert-Elliot channel model. Under the model, any time-window of width w
+contains either up to a random erasure or else erasure burst of length at most
+b (>= a). Thus the source-relay and relay-destination channels are modeled as
+(a_1, b_1, w_1, T_1) and (a_2, b_2, w_2, T_2) DCSW channels. We first derive an
+upper bound on the capacity of the three-node D&F relay network. We then show
+that the upper bound is tight for the parameter regime: max{b_1,
+b_2}|(T-b_1-b_2-max{a_1, a_2}+1), a1=a2 OR b1=b2 by constructing streaming
+codes achieving the bound. The code construction requires field size linear in
+T, and has decoding complexity equivalent to that of decoding an MDS code.",2207.04025v2
+2022-07-12,"Diversity of ghost notes in tubas, euphoniums and saxhorns","The ghost note is a natural note which can be played exclusively on bass
+brass instruments with a predominantly-expanding bore profile such as tubas,
+euphoniums or saxhorns. It stands between the pedal note-the lowest natural
+note playable, or first regime-and the instrument's second regime. However, if
+the interval between the pedal note and the second regime remains close to an
+octave regardless of the instrument, the interval between the pedal note and
+the ghost note vary from a minor third to a perfect fourth. References about
+this note are very scarce, and it is not commonly known among tuba players.This
+study shows that an elementary brass model describing the player coupled to the
+instrument is capable of bringing both the ghost and the pedal note to light.
+Here, we adopt a dynamical systems point of view and perform a bifurcation
+analysis using a software of numerical continuation. The numerical results
+provided in terms of frequency intervals between pedal note and ghost note are
+compared with frequency intervals experimentally inferred from recordings of
+seven different types of tuba, each of them being played by two professional
+tuba players.",2207.05395v3
+2022-07-20,Flow-based Visual Quality Enhancer for Super-resolution Magnetic Resonance Spectroscopic Imaging,"Magnetic Resonance Spectroscopic Imaging (MRSI) is an essential tool for
+quantifying metabolites in the body, but the low spatial resolution limits its
+clinical applications. Deep learning-based super-resolution methods provided
+promising results for improving the spatial resolution of MRSI, but the
+super-resolved images are often blurry compared to the experimentally-acquired
+high-resolution images. Attempts have been made with the generative adversarial
+networks to improve the image visual quality. In this work, we consider another
+type of generative model, the flow-based model, of which the training is more
+stable and interpretable compared to the adversarial networks. Specifically, we
+propose a flow-based enhancer network to improve the visual quality of
+super-resolution MRSI. Different from previous flow-based models, our enhancer
+network incorporates anatomical information from additional image modalities
+(MRI) and uses a learnable base distribution. In addition, we impose a guide
+loss and a data-consistency loss to encourage the network to generate images
+with high visual quality while maintaining high fidelity. Experiments on a
+1H-MRSI dataset acquired from 25 high-grade glioma patients indicate that our
+enhancer network outperforms the adversarial networks and the baseline
+flow-based methods. Our method also allows visual quality adjustment and
+uncertainty estimation.",2207.10181v1
+2022-07-24,Contention Resolution for Coded Radio Networks,"Randomized backoff protocols, such as exponential backoff, are a powerful
+tool for managing access to a shared resource, often a wireless communication
+channel (e.g., [1]). For a wireless device to transmit successfully, it uses a
+backoff protocol to ensure exclusive access to the channel. Modern radios,
+however, do not need exclusive access to the channel to communicate; in
+particular, they have the ability to receive useful information even when more
+than one device transmits at the same time. These capabilities have now been
+exploited for many years by systems that rely on interference cancellation,
+physical layer network coding and analog network coding to improve efficiency.
+For example, Zigzag decoding [56] demonstrated how a base station can decode
+messages sent by multiple devices simultaneously.
+  In this paper, we address the following question: Can we design a backoff
+protocol that is better than exponential backoff when exclusive channel access
+is not required. We define the Coded Radio Network Model, which generalizes
+traditional radio network models (e.g., [30]). We then introduce the Decodable
+Backoff Algorithm, a randomized backoff protocol that achieves an optimal
+throughput of $1-o(1)$. (Throughput $1$ is optimal, as simultaneous reception
+does not increase the channel capacity.) The algorithm breaks the constant
+throughput lower bound for traditional radio networks [47-49], showing the
+power of these new hardware capabilities.",2207.11824v1
+2022-07-25,Control of dephasing in spin qubits during coherent transport in silicon,"One of the key pathways towards scalability of spin-based quantum computing
+systems lies in achieving long-range interactions between electrons and
+increasing their inter-connectivity. Coherent spin transport is one of the most
+promising strategies to achieve this architectural advantage. Experimental
+results have previously demonstrated high fidelity transportation of spin
+qubits between two quantum dots in silicon and identified possible sources of
+error. In this theoretical study, we investigate these errors and analyze the
+impact of tunnel coupling, magnetic field and spin-orbit effects on the spin
+transfer process. The interplay between these effects gives rise to double dot
+configurations that include regimes of enhanced decoherence that should be
+avoided for quantum information processing. These conclusions permit us to
+extrapolate previous experimental conclusions and rationalize the future design
+of large scale quantum processors.",2207.11865v2
+2022-07-29,Orthogonal Spin Current Injected Magnetic Tunnel Junction for Convolutional Neural Networks,"We propose that a spin Hall effect driven magnetic tunnel junction device can
+be engineered to provide a continuous change in the resistance across it when
+injected with orthogonal spin currents. Using this concept, we develop a hybrid
+device-circuit simulation platform to design a network that realizes multiple
+functionalities of a convolutional neural network. At the atomistic level, we
+use the Keldysh non-equilibrium Green's function technique that is coupled
+self-consistently with the stochastic Landau-Lifshitz-Gilbert-Slonczewski
+equations, which in turn is coupled with the HSPICE circuit simulator. We
+demonstrate the simultaneous functionality of the proposed network to evaluate
+the rectified linear unit and max-pooling functionalities. We present a
+detailed power and error analysis of the designed network against the thermal
+stability factor of the free ferromagnets. Our results show that there exists a
+non-trivial power-error trade-off in the proposed network, which enables an
+energy-efficient network design based on unstable free ferromagnets with
+reliable outputs. The static power for the proposed ReLU circuit is $0.56\mu W$
+and whereas the energy cost of a nine-input rectified linear unit-max-pooling
+network with an unstable free ferromagnet($\Delta=15$) is $3.4pJ$ in the
+worst-case scenario. We also rationalize the magnetization stability of the
+proposed device by analyzing the vanishing torque gradient points.",2207.14603v3
+2022-08-09,Good locally repairable codes via propagation rules,"In classical coding theory, it is common to construct new codes via
+propagation rules. There are various propagation rules to construct classical
+block codes. However, propagation rules have not been extensively explored for
+constructions of locally repairable codes. In this paper, we introduce a few
+propagation rules to construct good locally repairable codes. To our surprise,
+these simple propagation rules produce a few interesting results. Firstly, by
+concatenating a locally repairable code as an inner code with a classical block
+code as an outer code, we obtain quite a few dimension-optimal binary locally
+repairable codes. Secondly, from this concatenation, we explicitly build a
+family of locally repairable codes that exceeds the Zyablov-type bound.
+Thirdly, by a lengthening propagation rule that adds some rows and columns from
+a parity-check matrix of a given linear code, we are able to produce a family
+of dimension-optimal binary locally repairable codes from the extended Hamming
+codes, and to convert a classical maximum distance separable (MDS) code into a
+Singleton-optimal locally repairable code. Furthermore, via the lengthening
+propagation rule, we greatly simplify the construction of a family of locally
+repairable codes in \cite[Theorem 5]{MX20} that breaks the asymptotic
+Gilbert-Varshamov bound. In addition, we make use of three other propagation
+rules to produce more dimension-optimal binary locally repairable codes.
+Finally, one of phenomena that we observe in this paper is that some trivial
+propagation rules in classical block codes do not hold anymore for locally
+repairable codes.",2208.04484v1
+2022-08-10,Forward volume magnetoacoustic spin wave excitation with micron-scale spatial resolution,"The interaction between surface acoustic waves (SAWs) and spin waves (SWs) in
+a piezoelectric-magnetic thin film heterostructure yields potential for the
+realization of novel microwave devices and applications in magnonics. In the
+present work, we characterize magnetoacoustic waves in three adjacent magnetic
+micro-stripes made from CoFe+Ga, CoFe, and CoFe+Pt with a single pair of
+tapered interdigital transducers (TIDTs). The magnetic micro-stripes were
+deposited by focused electron beam-induced deposition (FEBID) and focused ion
+beam-induced deposition (FIBID) direct-writing techniques. The transmission
+characteristics of the TIDTs are leveraged to selectively address the
+individual micro-stripes. Here, the external magnetic field is continuously
+rotated out of the plane of the magnetic thin film and the forward volume SW
+geometry is probed with the external magnetic field along the film normal. Our
+experimental findings are well explained by an extended phenomenological model
+based on a modified Landau-Lifshitz-Gilbert approach that considers SWs with
+nonzero wave vectors. Magnetoelastic excitation of forward volume SWs is
+possible because of the vertical shear strain $\varepsilon_{xz}$ of the
+Rayleigh-type SAW.",2208.05205v1
+2022-08-29,Programmable photonic integrated meshes for modular generation of optical entanglement links,"Large-scale generation of quantum entanglement between individually
+controllable qubits is at the core of quantum computing, communications, and
+sensing. Modular architectures of remotely-connected quantum technologies have
+been proposed for a variety of physical qubits, with demonstrations reported in
+atomic and all-photonic systems. However, an open challenge in these
+architectures lies in constructing high-speed and high-fidelity reconfigurable
+photonic networks for optically-heralded entanglement among target qubits. Here
+we introduce a programmable photonic integrated circuit (PIC), realized in a
+piezo-actuated silicon nitride (SiN)-in-oxide CMOS-compatible process, that
+implements an N x N Mach-Zehnder mesh (MZM) capable of high-speed execution of
+linear optical transformations. The visible-spectrum photonic integrated mesh
+is programmed to generate optical connectivity on up to N = 8 inputs for a
+range of optically-heralded entanglement protocols. In particular, we
+experimentally demonstrated optical connections between 16 independent pairwise
+mode couplings through the MZM, with optical transformation fidelities
+averaging 0.991 +/- 0.0063. The PIC's reconfigurable optical connectivity
+suffices for the production of 8-qubit resource states as building blocks of
+larger topological cluster states for quantum computing. Our programmable PIC
+platform enables the fast and scalable optical switching technology necessary
+for network-based quantum information processors.",2208.13911v1
+2022-09-15,Almost Ramanujan Expanders from Arbitrary Expanders via Operator Amplification,"We give an efficient algorithm that transforms any bounded degree expander
+graph into another that achieves almost optimal (namely, near-quadratic, $d
+\leq 1/\lambda^{2+o(1)}$) trade-off between (any desired) spectral expansion
+$\lambda$ and degree $d$. Furthermore, the algorithm is local: every vertex can
+compute its new neighbors as a subset of its original neighborhood of radius
+$O(\log(1/\lambda))$. The optimal quadratic trade-off is known as the Ramanujan
+bound, so our construction gives almost Ramanujan expanders from arbitrary
+expanders.
+  The locality of the transformation preserves structural properties of the
+original graph, and thus has many consequences. Applied to Cayley graphs, our
+transformation shows that any expanding finite group has almost Ramanujan
+expanding generators. Similarly, one can obtain almost optimal explicit
+constructions of quantum expanders, dimension expanders, monotone expanders,
+etc., from existing (suboptimal) constructions of such objects. Another
+consequence is a ""derandomized"" random walk on the original (suboptimal)
+expander with almost optimal convergence rate. Our transformation also applies
+when the degree is not bounded or the expansion is not constant.
+  We obtain our results by a generalization of Ta-Shma's technique in his
+breakthrough paper [STOC 2017], used to obtain explicit almost optimal binary
+codes. Specifically, our spectral amplification extends Ta-Shma's analysis of
+bias amplification from scalars to matrices of arbitrary dimension in a very
+natural way. Curiously, while Ta-Shma's explicit bias amplification
+derandomizes a well-known probabilistic argument (underlying the
+Gilbert--Varshamov bound), there seems to be no known probabilistic (or other
+existential) way of achieving our explicit (""high-dimensional"") spectral
+amplification.",2209.07024v1
+2022-09-15,An analytical study of the MHD clamshell instability on a sphere,"This paper studies the instability of two-dimensional magnetohydrodynamic
+(MHD) systems on a sphere using analytical methods. The underlying flow
+consists of a zonal differential rotation and a toroidal magnetic field is
+present. Semicircle rules that prescribe the possible domain of the wave
+velocity in the complex plane for general flow and field profiles are derived.
+The paper then sets out an analytical study of the `clamshell instability',
+which features field lines on the two hemispheres tilting in opposite
+directions (Cally 2001, Sol. Phys. vol. 199, pp. 231--249). An asymptotic
+solution for the instability problem is derived for the limit of weak shear of
+the zonal flow, via the method of matched asymptotic expansions. It is shown
+that when the zonal flow is solid body rotation, there exists a neutral mode
+that tilts the magnetic field lines, referred to as the `tilting mode'. A weak
+shear of the zonal flow excites the critical layer of the tilting mode, which
+reverses the tilting direction to form the clamshell pattern and induces the
+instability. The asymptotic solution provides insights into properties of the
+instability for a range of flow and field profiles. A remarkable feature is
+that the magnetic field affects the instability only through its local
+behaviour in the critical layer.",2209.07349v1
+2022-09-15,$\tilde{O}(n+\mathrm{poly}(k))$-time Algorithm for Bounded Tree Edit Distance,"Computing the edit distance of two strings is one of the most basic problems
+in computer science and combinatorial optimization. Tree edit distance is a
+natural generalization of edit distance in which the task is to compute a
+measure of dissimilarity between two (unweighted) rooted trees with node
+labels. Perhaps the most notable recent application of tree edit distance is in
+NoSQL big databases, such as MongoDB, where each row of the database is a JSON
+document represented as a labeled rooted tree, and finding dissimilarity
+between two rows is a basic operation. Until recently, the fastest algorithm
+for tree edit distance ran in cubic time (Demaine, Mozes, Rossman, Weimann;
+TALG'10); however, Mao (FOCS'21) broke the cubic barrier for the tree edit
+distance problem using fast matrix multiplication.
+  Given a parameter $k$ as an upper bound on the distance, an $O(n+k^2)$-time
+algorithm for edit distance has been known since the 1980s due to the works of
+Myers (Algorithmica'86) and Landau and Vishkin (JCSS'88). The existence of an
+$\tilde{O}(n+\mathrm{poly}(k))$-time algorithm for tree edit distance has been
+posed as an open question, e.g., by Akmal and Jin (ICALP'21), who gave a
+state-of-the-art $\tilde{O}(nk^2)$-time algorithm. In this paper, we answer
+this question positively.",2209.07524v1
+2022-09-23,Multiplexed control of spin quantum memories in a photonic circuit,"A central goal in many quantum information processing applications is a
+network of quantum memories that can be entangled with each other while being
+individually controlled and measured with high fidelity. This goal has
+motivated the development of programmable photonic integrated circuits (PICs)
+with integrated spin quantum memories using diamond color center spin-photon
+interfaces. However, this approach introduces a challenge in the microwave
+control of individual spins within closely packed registers. Here, we present a
+quantum-memory-integrated photonics platform capable of (i) the integration of
+multiple diamond color center spins into a cryogenically compatible, high-speed
+programmable PIC platform; (ii) selective manipulation of individual spin
+qubits addressed via tunable magnetic field gradients; and (iii) simultaneous
+control of multiple qubits using numerically optimized microwave pulse shaping.
+The combination of localized optical control, enabled by the PIC platform,
+together with selective spin manipulation opens the path to scalable quantum
+networks on intra-chip and inter-chip platforms.",2209.11853v2
+2022-09-26,A detailed star formation history for the extremely diffuse Andromeda XIX dwarf galaxy,"We present deep imaging of the ultra-diffuse Andromeda XIX dwarf galaxy from
+the Advance Camera for Surveys on the Hubble Space Telescope which resolves its
+stellar populations to below the oldest main sequence turn-off. We derive a
+full star formation history for the galaxy using MATCH, and find no evidence of
+star formation in the past 8 Gyr. We calculate a quenching time of
+$\tau_{90}=9.7\pm0.2$~Gyr, suggesting Andromeda~XIX ceased forming stars very
+early on. This early quenching, combined with its extremely large half-light
+radius, low density dark matter halo and lower than expected metallicity make
+it a unique galaxy within the Local Group and raises questions about how it
+formed. The early quenching time allows us to rule out feedback from bursty
+star formation as a means to explain its diffuse stellar population and low
+density dark matter halo. We find that the extended stellar population, low
+density halo and star formation could be explained by either tidal interactions
+(such as tidal shocking) or by late dry mergers, with the latter also
+explaining its low metallicity. Proper motions and detailed abundances would
+allow us to distinguish between these two scenarios.",2209.12912v1
+2022-10-06,Scalable photonic integrated circuits for programmable control of atomic systems,"Advances in laser technology have driven discoveries in atomic, molecular,
+and optical (AMO) physics and emerging applications, from quantum computers
+with cold atoms or ions, to quantum networks with solid-state color centers.
+This progress is motivating the development of a new generation of
+""programmable optical control"" systems, characterized by criteria (C1) visible
+(VIS) and near-infrared (IR) wavelength operation, (C2) large channel counts
+extensible beyond 1000s of individually addressable atoms, (C3) high intensity
+modulation extinction and (C4) repeatability compatible with low gate errors,
+and (C5) fast switching times. Here, we address these challenges by introducing
+an atom control architecture based on VIS-IR photonic integrated circuit (PIC)
+technology. Based on a complementary metal-oxide-semiconductor (CMOS)
+fabrication process, this Atom-control PIC (APIC) technology meets the system
+requirements (C1)-(C5). As a proof of concept, we demonstrate a 16-channel
+silicon nitride based APIC with (5.8$\pm$0.4) ns response times and -30 dB
+extinction ratio at a wavelength of 780 nm. This work demonstrates the
+suitability of PIC technology for quantum control, opening a path towards
+scalable quantum information processing based on optically-programmable atomic
+systems.",2210.03100v2
+2022-10-10,Andreev processes in mesoscopic multi-terminal graphene Josephson junctions,"There is growing interest in using multi-terminal Josephson junctions (MTJJs)
+as a platform to artificially emulate topological phases and to investigate
+complex superconducting mechanisms such as quartet and multiplet Cooper
+pairings. Current experimental signatures in MTJJs have led to conflicting
+interpretations of the salient features. In this work, we report a
+collaborative experimental and theoretical investigation of graphene-based
+four-terminal Josephson junctions. We observe resonant features in the
+differential resistance maps that resemble those ascribed to multiplet Cooper
+pairings. To understand these features, we model our junctions using a circuit
+network of coupled two-terminal resistively and capacitively shunted junctions
+(RCSJs). Under appropriate bias current, the model predicts that a current
+flowing between two diagonal terminals in a four-terminal geometry may be
+represented as a sinusoidal function of a weighted sum of the superconducting
+phases. We show that starting from a semi-classical model with diffusive
+current-phase relations, the MTJJ effectively emulates a general form of the
+expected current-phase relation for multiplet Cooper pairings. Our study
+therefore suggests that differential resistance measurements alone are
+insufficient to conclusively distinguish resonant Andreev reflection processes
+from semi-classical circuit-network effects.",2210.04408v3
+2022-10-10,Infrared Remote Sensing Using Low Noise Avalanche Photodiode Detector,"For a remote sensing optical payload to achieve a Ground Sampling Distance of
+~ 10-30 m, a critical problem is platform-induced motion blur. While forward
+motion compensation can reduce this transit speed, it comes at the expense of a
+more challenging satellite attitude control system and induces a variable
+observation/illumination angle. This relative motion can be frozen out by
+simply reading the sensor system at a frame rate that matches the ground
+resolution element's pixel crossing time. To achieve high resolution using this
+Time-Delay Integration (TDI)-like approach requires high speed and hence near
+""zero"" readout noise detector arrays to avoid swamping the observed signal.
+This requires associated control electronics for fast frame readout and direct
+interface with smart- Artificial Intelligence (AI) onboard processing. With
+this technique, the platform freezes out its movement concerning the ground,
+reducing the demands placed on the attitude control systems, which can
+otherwise be difficult to implement on a small satellite platform. Here we
+report the Australian National University's OzFuel mission which applies this
+technical solution to deliver high ground resolution via high frame rate
+imaging. OzFuel is built around the Leonardo SAPHIRA Mercury Cadmium Telluride
+linear mode electron avalanche photodiode (LMeAPD) detector and the in-house
+developed Rosella electronics control system. The mission will deliver an
+integrated sensor system in a suite of Short-Wave Infrared (SWIR) passbands
+dedicated to monitoring the flammability of Eucalypt trees. The OzFuel mission
+concept focuses on the application of SWIR remote sensing data to deliver a
+strategic evaluation of fuel loads and moisture content in the bushfire-prone
+Australian environment.",2210.04770v1
+2022-10-17,On construction of quantum codes with dual-containing quasi-cyclic codes,"One of the main objectives of quantum error-correction theory is to construct
+quantum codes with optimal parameters and properties. In this paper, we propose
+a class of 2-generator quasi-cyclic codes and study their applications in the
+construction of quantum codes over small fields. Firstly, some sufficient
+conditions for these 2-generator quasi-cyclic codes to be dual-containing
+concerning Hermitian inner product are determined. Then, we utilize these
+Hermitian dual-containing quasi-cyclic codes to produce quantum codes via the
+famous Hermitian construction. Moreover, we present a lower bound on the
+minimum distance of these quasi-cyclic codes, which is helpful to construct
+quantum codes with larger lengths and dimensions. As the computational results,
+many new quantum codes that exceed the quantum Gilbert-Varshamov bound are
+constructed over $F_q$, where $q$ is $2,3,4,5$. In particular, 16 binary
+quantum codes raise the lower bound on the minimum distance in Grassl's table
+\cite{Grassl:codetables}. In nonbinary cases, many quantum codes are new or
+have better parameters than those in the literature.",2210.08716v1
+2022-10-18,Intense γ-photon and high-energy electron production by neutron irradiation: effects of nuclear excitations on reactor materials,"The effects of neutron irradiation on materials are often interpreted in
+terms of atomic recoils, initiated by neutron impacts and producing crystal
+lattice defects. In addition, there is a remarkable two-step process, strongly
+pronounced in the medium-weight and heavy elements. This process involves the
+generation of energetic {\gamma} photons in nonelastic collisions of neutrons
+with atomic nuclei, achieved via capture and inelastic reactions. Subsequently,
+high-energy electrons are excited through the scattering of {\gamma} photons by
+the atomic electrons. We derive and validate equations enabling a fast and
+robust evaluation of photon and electron fluxes produced by the neutrons in the
+bulk of materials. The two-step n-{\gamma}-e scattering creates a
+nonequilibrium dynamically fluctuating steady-state population of high-energy
+electrons, with the spectra of photon and electron energies extending well into
+the mega-electron-volt range. This stimulates vacancy diffusion through
+electron-triggered atomic recoils, primarily involving vacancy-impurity
+dissociation, even if thermal activation is ineffective. Tungsten converts the
+energy of fusion or fission neutrons into a flux of {\gamma} radiation at the
+conversion efficiency approaching 99%, with implications for structural
+materials, superconductors, and insulators, as well as phenomena like
+corrosion, and helium and hydrogen isotope retention.",2210.09667v2
+2022-11-06,A framework for leveraging machine learning tools to estimate personalized survival curves,"The conditional survival function of a time-to-event outcome subject to
+censoring and truncation is a common target of estimation in survival analysis.
+This parameter may be of scientific interest and also often appears as a
+nuisance in nonparametric and semiparametric problems. In addition to classical
+parametric and semiparametric methods (e.g., based on the Cox proportional
+hazards model), flexible machine learning approaches have been developed to
+estimate the conditional survival function. However, many of these methods are
+either implicitly or explicitly targeted toward risk stratification rather than
+overall survival function estimation. Others apply only to discrete-time
+settings or require inverse probability of censoring weights, which can be as
+difficult to estimate as the outcome survival function itself. Here, we employ
+a decomposition of the conditional survival function in terms of observable
+regression models in which censoring and truncation play no role. This allows
+application of an array of flexible regression and classification methods
+rather than only approaches that explicitly handle the complexities inherent to
+survival data. We outline estimation procedures based on this decomposition,
+empirically assess their performance, and demonstrate their use on data from an
+HIV vaccine trial.",2211.03031v4
+2022-11-14,High-resolution single-shot spiral diffusion-weighted imaging at 7T using expanded encoding with compressed sensing,"Purpose: The expanded encoding model incorporates spatially- and time-varying
+field perturbations for correction during reconstruction. So far, these
+reconstructions have used the conjugate gradient method with early stopping
+used as implicit regularization. However, this approach is likely suboptimal
+for low-SNR cases like diffusion or high-resolution MRI. Here, we investigate
+the extent that l1-wavelet regularization, or equivalently compressed sensing
+(CS), combined with expanded encoding improves trade-offs between spatial
+resolution, readout time and SNR for single-shot spiral diffusion-weighted
+imaging at 7T. The reconstructions were performed using our open-source
+GPU-enabled reconstruction toolbox, MatMRI, that allows inclusion of the
+different components of the expanded encoding model, with or without CS.
+Methods: In vivo accelerated single-shot spirals were acquired with five
+acceleration factors (2-6) and three in-plane spatial resolutions (1.5, 1.3,
+and 1.1 mm). From the in vivo reconstructions, we estimated diffusion tensors
+and computed fractional anisotropy maps. Then, simulations were used to
+quantitatively investigate and validate the impact of CS-based regularization
+on image quality when compared to a known ground truth. Results: In vivo
+reconstructions revealed improved image quality with retainment of small
+features when CS was used. Simulations showed that the joint use of the
+expanded encoding model and CS improves accuracy of image reconstructions
+(reduced mean-squared error) over the range of acceleration factors
+investigated. Conclusion: The expanded encoding model and CS regularization are
+complementary tools for single-shot spiral diffusion MRI, which enables both
+higher spatial resolutions and higher acceleration factors.",2211.07532v1
+2022-11-17,On universal butterfly and antisymmetric magnetoresistances,"Butterfly magnetoresistance (BMR) and antisymmetric magnetoresistance (ASMR)
+are about a butterfly-cross curve and a curve with one peak and one valley when
+a magnetic field is swept up and down along a fixed direction. Other than the
+parallelogram-shaped magnetoresistance-curve (MR-curve) often observed in
+magnetic memory devices, BMR and ASMR are two ubiquitous types of MR-curves
+observed in diversified magnetic systems, including van der Waals materials,
+strongly correlated systems, and traditional magnets. Here, we reveal the
+general principles and the picture behind the BMR and the ASMR that do not
+depend on the detailed mechanisms of magnetoresistance: 1) The systems exhibit
+hysteresis loops, common for most magnetic materials with coercivities. 2) The
+magnetoresistance of the magnetic structures in a large positive magnetic field
+and in a large negative magnetic field is approximately the same. With the
+generalized Ohm's law in magnetic materials, these principles explain why most
+BMR appears in the longitudinal resistance measurements and is very rare in the
+Hall resistance measurements. Simple toy models, in which the
+Landau-Lifshitz-Gilbert equation governs magnetization, are used to demonstrate
+the principles and explain the appearance and disappearance of BMR in various
+experiments. Our finding provides a simple picture to understand
+magnetoresistance-related experiments.",2211.09369v1
+2022-12-22,Photon production rate from Transverse-Longitudinal ($T-L$) mesonic correlator on the lattice,"Thermal photons from the QGP provide important information about the
+interaction among plasma constituents. The photon production rate from a
+thermally equilibrated system is proportional to the transverse spectral
+function $\rho_T(\omega=|\vec k|, \vec k)$. One can also calculate the photon
+production rate from the difference between $\rho_T(\omega,\vec k)$
+(transverse) and $\rho_L(\omega,\vec k)$ (longitudinal) projections, as
+$\rho_L$ vanishes on the photon point. Because the UV part of $\rho_T-\rho_L$
+is suppressed, the corresponding Euclidean correlator receives most of its
+contribution from the IR part. We calculate the $T\!-\!L$ correlator on
+$N_f=2+1$ flavour HISQ configurations with $m_l=m_s/5$ at temperature of about
+$1.15\,T_{pc}$ (220 MeV). We have used two ans\""{a}tze for the spectral
+function: 1) A polynomial connected to the UV region consistent with OPE
+expansion and 2) a hydro-inspired spectral function. We have also applied the
+Backus-Gilbert method to estimate the spectral function. All these different
+approaches are combined to estimate the photon production rate.",2212.11509v2
+2023-01-12,Incremental Dead State Detection in Logarithmic Time,"Identifying live and dead states in an abstract transition system is a
+recurring problem in formal verification; for example, it arises in our recent
+work on efficiently deciding regex constraints in SMT. However,
+state-of-the-art graph algorithms for maintaining reachability information
+incrementally (that is, as states are visited and before the entire state space
+is explored) assume that new edges can be added from any state at any time,
+whereas in many applications, outgoing edges are added from each state as it is
+explored. To formalize the latter situation, we propose guided incremental
+digraphs (GIDs), incremental graphs which support labeling closed states
+(states which will not receive further outgoing edges). Our main result is that
+dead state detection in GIDs is solvable in $O(\log m)$ amortized time per edge
+for $m$ edges, improving upon $O(\sqrt{m})$ per edge due to Bender, Fineman,
+Gilbert, and Tarjan (BFGT) for general incremental directed graphs.
+  We introduce two algorithms for GIDs: one establishing the logarithmic time
+bound, and a second algorithm to explore a lazy heuristics-based approach. To
+enable an apples-to-apples experimental comparison, we implemented both
+algorithms, two simpler baselines, and the state-of-the-art BFGT baseline using
+a common directed graph interface in Rust. Our evaluation shows $110$-$530$x
+speedups over BFGT for the largest input graphs over a range of graph classes,
+random graphs, and graphs arising from regex benchmarks.",2301.05308v2
+2023-02-07,Computational capability for physical reservoir computing using a spin-torque oscillator with two free layers,"A numerical analysis on the computational capability of physical reservoir
+computing utilizing a spin-torque oscillator with two free layers is reported.
+Conventional spintronics devices usually consist of two ferromagnets, where the
+direction of magnetization in one layer, called the free layer, can move while
+that of the other, the reference layer, is fixed. Recently, however, devices
+with two free layers, where the reference layer is replaced by another free
+layer, have been developed for various practical applications. Adding another
+free layer drastically changes the dynamical response of the device through the
+couplings via the spin-transfer effect and the dipole magnetic field. A
+numerical simulation of the Landau-Lifshitz-Gilbert equation and a statistical
+analyses of the Lyapunov exponent and the synchronization index reveal the
+appearance of an amplitude-modulated oscillation and chaos in the oscillators
+with two free layers. Such complex dynamics qualitatively change the
+computational capability of physical reservoir computing because the
+computational resource is dynamics of the physical system. An evaluation of the
+short-term memory capacity clarifies that oscillators with two free layers have
+a larger capacity than those of conventional oscillators. An enhancement in
+capacity near the edge of echo state property, i.e., the boundary between zero
+and finite synchronization index, is also found.",2302.03769v1
+2023-02-13,Ultra-bright single photon source based on an atomically thin material,"Solid-state single photon sources are central building blocks in quantum
+communication networks and on-chip quantum information processing. Atomically
+thin crystals were established as possible candidates to emit non-classical
+states of light, however, the performance of monolayer-based single photon
+sources has so far been lacking behind state-of-the-art devices based on volume
+crystals. Here, we implement a single photon source based on an atomically thin
+sheet of WSe2 coupled to a spectrally tunable optical cavity. It is
+characterized by a high single photon purity with a $g^{(2)}(0)$ value as low
+as $4.7 \pm 0.7 \%$ and a record-high first lens brightness of linearly
+polarized photons as large as $65 \pm 4 \%$. Interestingly, the high
+performance of our devices allows us to observe genuine quantum interference
+phenomena in a Hong-Ou-Mandel experiment. Our results demonstrate that open
+cavities and two-dimensional materials constitute an excellent platform for
+ultra-bright quantum light sources: the unique properties of such
+two-dimensional materials and the versatility of open cavities open an
+inspiring avenue for novel quantum optoelectronic devices.",2302.06340v1
+2023-02-21,A Prompt Pattern Catalog to Enhance Prompt Engineering with ChatGPT,"Prompt engineering is an increasingly important skill set needed to converse
+effectively with large language models (LLMs), such as ChatGPT. Prompts are
+instructions given to an LLM to enforce rules, automate processes, and ensure
+specific qualities (and quantities) of generated output. Prompts are also a
+form of programming that can customize the outputs and interactions with an
+LLM. This paper describes a catalog of prompt engineering techniques presented
+in pattern form that have been applied to solve common problems when conversing
+with LLMs. Prompt patterns are a knowledge transfer method analogous to
+software patterns since they provide reusable solutions to common problems
+faced in a particular context, i.e., output generation and interaction when
+working with LLMs. This paper provides the following contributions to research
+on prompt engineering that apply LLMs to automate software development tasks.
+First, it provides a framework for documenting patterns for structuring prompts
+to solve a range of problems so that they can be adapted to different domains.
+Second, it presents a catalog of patterns that have been applied successfully
+to improve the outputs of LLM conversations. Third, it explains how prompts can
+be built from multiple patterns and illustrates prompt patterns that benefit
+from combination with other prompt patterns.",2302.11382v1
+2023-03-11,Power efficient ReLU design for neuromorphic computing using spin Hall effect,"We demonstrate a magnetic tunnel junction injected with spin Hall current to
+exhibit linear rotation of magnetization of the free-ferromagnet using only the
+spin current. Using the linear resistance change of the MTJ, we devise a
+circuit for the rectified linear activation (ReLU) function of the artificial
+neuron. We explore the role of different spin Hall effect (SHE) heavy metal
+layers on the power consumption of the ReLU circuit. We benchmark the power
+consumption of the ReLU circuit with different SHE layers by defining a new
+parameter called the spin Hall power factor. It combines the spin Hall angle,
+resistivity, and thickness of the heavy metal layer, which translates to the
+power consumption of the different SHE layers during spin-orbit
+switching/rotation of the free FM. We employ a hybrid spintronics-CMOS
+simulation framework that couples Keldysh non-equilibrium Green's function
+formalism with Landau-Lifshitz-Gilbert-Slonzewski equations and the HSPICE
+circuit simulator to account for diverse physics of spin-transport and the CMOS
+elements in our proposed ReLU design. We also demonstrate the robustness of the
+proposed ReLU circuit against thermal noise and non-trivial power-error
+trade-off that enables the use of an unstable free-ferromagnet for
+energy-efficient design. Using the proposed circuit, we evaluate the
+performance of the convolutional neural network for MNIST datasets and
+demonstrate comparable classification accuracies to the ideal ReLU with an
+energy consumption of 75 $pJ$ per sample.",2303.06463v1
+2023-03-28,Optimal Scheduling Policies for Remote Estimation of Autoregressive Markov Processes over Time-Correlated Fading Channel,"We consider the problem of transmission scheduling for the remote estimation
+of a discrete-time autoregressive Markov process that is driven by white
+Gaussian noise. A sensor observes this process, and then decides to either
+encode the current state of this process into a data packet and attempts to
+transmit it to the estimator over an unreliable wireless channel modeled as a
+Gilbert-Elliott channel, or does not send any update. Each transmission attempt
+consumes $\lambda$ units of transmission power, and the remote estimator is
+assumed to be linear. The channel state is revealed only via the feedback
+(ACK\slash NACK) of a transmission, and hence the channel state is not revealed
+if no transmission occurs. The goal of the scheduler is to minimize the
+expected value of an infinite-horizon cumulative discounted cost, in which the
+instantaneous cost is composed of the following two quantities: (i)~squared
+estimation error, (ii) transmission power. We show that this problem can
+equivalently be posed as a partially observable Markov decision process
+(POMDP), in which the scheduler maintains a belief about the current state of
+the channel, and makes decisions on the basis of the current value of the
+estimation error, and the belief state.~We then show that the optimal policy is
+of threshold-type, i.e. for each value of the estimation error $e$, there is a
+threshold $b\ust(e)$ such that when the error is equal to $e$, then it is
+optimal to transmit only when the current belief state is greater than
+$b\ust(e)$.",2303.16285v1
+2023-04-14,Study on Soft Robotic Pinniped Locomotion,"Legged locomotion is a highly promising but under-researched subfield within
+the field of soft robotics. The compliant limbs of soft-limbed robots offer
+numerous benefits, including the ability to regulate impacts, tolerate falls,
+and navigate through tight spaces. These robots have the potential to be used
+for various applications, such as search and rescue, inspection, surveillance,
+and more. The state-of-the-art still faces many challenges, including limited
+degrees of freedom, a lack of diversity in gait trajectories, insufficient limb
+dexterity, and limited payload capabilities. To address these challenges, we
+develop a modular soft-limbed robot that can mimic the locomotion of pinnipeds.
+By using a modular design approach, we aim to create a robot that has improved
+degrees of freedom, gait trajectory diversity, limb dexterity, and payload
+capabilities. We derive a complete floating-base kinematic model of the
+proposed robot and use it to generate and experimentally validate a variety of
+locomotion gaits. Results show that the proposed robot is capable of
+replicating these gaits effectively. We compare the locomotion trajectories
+under different gait parameters against our modeling results to demonstrate the
+validity of our proposed gait models.",2304.06945v1
+2023-04-19,Local object crop collision network for efficient simulation of non-convex objects in GPU-based simulators,"Our goal is to develop an efficient contact detection algorithm for
+large-scale GPU-based simulation of non-convex objects. Current GPU-based
+simulators such as IsaacGym and Brax must trade-off speed with fidelity,
+generality, or both when simulating non-convex objects. Their main issue lies
+in contact detection (CD): existing CD algorithms, such as
+Gilbert-Johnson-Keerthi (GJK), must trade off their computational speed with
+accuracy which becomes expensive as the number of collisions among non-convex
+objects increases. We propose a data-driven approach for CD, whose accuracy
+depends only on the quality and quantity of offline dataset rather than online
+computation time. Unlike GJK, our method inherently has a uniform computational
+flow, which facilitates efficient GPU usage based on advanced compilers such as
+XLA (Accelerated Linear Algebra). Further, we offer a data-efficient solution
+by learning the patterns of colliding local crop object shapes, rather than
+global object shapes which are harder to learn. We demonstrate our approach
+improves the efficiency of existing CD methods by a factor of 5-10 for
+non-convex objects with comparable accuracy. Using the previous work on contact
+resolution for a neural-network-based contact detector, we integrate our CD
+algorithm into the open-source GPU-based simulator, Brax, and show that we can
+improve the efficiency over IsaacGym and generality over standard Brax. We
+highly recommend the videos of our simulator included in the supplementary
+materials.",2304.09439v2
+2023-04-25,Semantic Compression With Large Language Models,"The rise of large language models (LLMs) is revolutionizing information
+retrieval, question answering, summarization, and code generation tasks.
+However, in addition to confidently presenting factually inaccurate information
+at times (known as ""hallucinations""), LLMs are also inherently limited by the
+number of input and output tokens that can be processed at once, making them
+potentially less effective on tasks that require processing a large set or
+continuous stream of information. A common approach to reducing the size of
+data is through lossless or lossy compression. Yet, in some cases it may not be
+strictly necessary to perfectly recover every detail from the original data, as
+long as a requisite level of semantic precision or intent is conveyed.
+  This paper presents three contributions to research on LLMs. First, we
+present the results from experiments exploring the viability of approximate
+compression using LLMs, focusing specifically on GPT-3.5 and GPT-4 via ChatGPT
+interfaces. Second, we investigate and quantify the capability of LLMs to
+compress text and code, as well as to recall and manipulate compressed
+representations of prompts. Third, we present two novel metrics -- Exact
+Reconstructive Effectiveness (ERE) and Semantic Reconstruction Effectiveness
+(SRE) -- that quantify the level of preserved intent between text compressed
+and decompressed by the LLMs we studied. Our initial results indicate that
+GPT-4 can effectively compress and reconstruct text while preserving the
+semantic essence of the original text, providing a path to leverage
+$\sim$5$\times$ more tokens than present limits allow.",2304.12512v1
+2023-04-28,Optimal majority rules and quantitative Condorcet properties of setwise Kemeny voting schemes,"The important Kemeny problem, which consists of computing median consensus
+rankings of an election with respect to the Kemeny voting rule, admits
+important applications in biology and computational social choice and was
+generalized recently via an interesting setwise approach by Gilbert et. al. Our
+first results establish optimal quantitative extensions of the Unanimity
+property and the well-known $3/4$-majority rule of Betzler et al. for the
+classical Kemeny median problem. Moreover, by elaborating an exhaustive list of
+quantified axiomatic properties (such as the Condorcet and Smith criteria, the
+$5/6$-majority rule, etc.) of the $3$-wise Kemeny rule where not only pairwise
+comparisons but also the discordance between the winners of subsets of three
+candidates are also taken into account, we come to the conclusion that the
+$3$-wise Kemeny voting scheme induced by the $3$-wise Kendall-tau distance
+presents interesting advantages in comparison with the classical Kemeny rule.
+For example, it satisfies several improved manipulation-proof properties. Since
+the $3$-wise Kemeny problem is NP-hard, our results also provide some of the
+first useful space reduction techniques by determining the relative orders of
+pairs of alternatives. Our works suggest similar interesting properties of
+higher setwise Kemeny voting schemes which justify and compensate for the more
+expensive computational cost than the classical Kemeny scheme.",2304.14980v1
+2023-05-25,Packaging code for reproducible research in the public sector,"The effective and ethical use of data to inform decision-making offers huge
+value to the public sector, especially when delivered by transparent,
+reproducible, and robust data processing workflows. One way that governments
+are unlocking this value is through making their data publicly available,
+allowing more people and organisations to derive insights. However, open data
+is not enough in many cases: publicly available datasets need to be accessible
+in an analysis-ready form from popular data science tools, such as R and
+Python, for them to realise their full potential.
+  This paper explores ways to maximise the impact of open data with reference
+to a case study of packaging code to facilitate reproducible analysis. We
+present the jtstats project, which consists of R and Python packages for
+importing, processing, and visualising large and complex datasets representing
+journey times, for many modes and purposes at multiple geographic levels,
+released by the UK Department of Transport. jtstats shows how domain specific
+packages can enable reproducible research within the public sector and beyond,
+saving duplicated effort and reducing the risks of errors from repeated
+analyses. We hope that the jtstats project inspires others, particularly those
+in the public sector, to add value to their data sets by making them more
+accessible.",2305.16205v1
+2023-05-25,COMPLETE: A flagship mission for complete understanding of 3D coronal magnetic energy release,"COMPLETE is a flagship mission concept combining broadband spectroscopic
+imaging and comprehensive magnetography from multiple viewpoints around the Sun
+to enable tomographic reconstruction of 3D coronal magnetic fields and
+associated dynamic plasma properties, which provide direct diagnostics of
+energy release. COMPLETE re-imagines the paradigm for solar remote-sensing
+observations through purposefully co-optimized detectors distributed on
+multiple spacecraft that operate as a single observatory, linked by a
+comprehensive data/model assimilation strategy to unify individual observations
+into a single physical framework. We describe COMPLETE's science goals,
+instruments, and mission implementation. With targeted investment by NASA,
+COMPLETE is feasible for launch in 2032 to observe around the maximum of Solar
+Cycle 26.",2305.16533v1
+2023-05-25,Magnetic Energy Powers the Corona: How We Can Understand its 3D Storage & Release,"The coronal magnetic field is the prime driver behind many as-yet unsolved
+mysteries: solar eruptions, coronal heating, and the solar wind, to name a few.
+It is, however, still poorly observed and understood. We highlight key
+questions related to magnetic energy storage, release, and transport in the
+solar corona, and their relationship to these important problems. We advocate
+for new and multi-point co-optimized measurements, sensitive to magnetic field
+and other plasma parameters, spanning from optical to $\gamma$-ray wavelengths,
+to bring closure to these long-standing and fundamental questions. We discuss
+how our approach can fully describe the 3D magnetic field, embedded plasma,
+particle energization, and their joint evolution to achieve these objectives.",2305.17146v1
+2023-05-27,Optimization's Neglected Normative Commitments,"Optimization is offered as an objective approach to resolving complex,
+real-world decisions involving uncertainty and conflicting interests. It drives
+business strategies as well as public policies and, increasingly, lies at the
+heart of sophisticated machine learning systems. A paradigm used to approach
+potentially high-stakes decisions, optimization relies on abstracting the real
+world to a set of decision(s), objective(s) and constraint(s). Drawing from the
+modeling process and a range of actual cases, this paper describes the
+normative choices and assumptions that are necessarily part of using
+optimization. It then identifies six emergent problems that may be neglected:
+1) Misspecified values can yield optimizations that omit certain imperatives
+altogether or incorporate them incorrectly as a constraint or as part of the
+objective, 2) Problematic decision boundaries can lead to faulty modularity
+assumptions and feedback loops, 3) Failing to account for multiple agents'
+divergent goals and decisions can lead to policies that serve only certain
+narrow interests, 4) Mislabeling and mismeasurement can introduce bias and
+imprecision, 5) Faulty use of relaxation and approximation methods,
+unaccompanied by formal characterizations and guarantees, can severely impede
+applicability, and 6) Treating optimization as a justification for action,
+without specifying the necessary contextual information, can lead to ethically
+dubious or faulty decisions. Suggestions are given to further understand and
+curb the harms that can arise when optimization is used wrongfully.",2305.17465v2
+2023-05-30,Hardness of Approximation in PSPACE and Separation Results for Pebble Games,"We consider the pebble game on DAGs with bounded fan-in introduced in
+[Paterson and Hewitt '70] and the reversible version of this game in [Bennett
+'89], and study the question of how hard it is to decide exactly or
+approximately the number of pebbles needed for a given DAG in these games. We
+prove that the problem of eciding whether $s$~pebbles suffice to reversibly
+pebble a DAG $G$ is PSPACE-complete, as was previously shown for the standard
+pebble game in [Gilbert, Lengauer and Tarjan '80]. Via two different graph
+product constructions we then strengthen these results to establish that both
+standard and reversible pebbling space are PSPACE-hard to approximate to within
+any additive constant. To the best of our knowledge, these are the first
+hardness of approximation results for pebble games in an unrestricted setting
+(even for polynomial time). Also, since [Chan '13] proved that reversible
+pebbling is equivalent to the games in [Dymond and Tompa '85] and [Raz and
+McKenzie '99], our results apply to the Dymond--Tompa and Raz--McKenzie games
+as well, and from the same paper it follows that resolution depth is
+PSPACE-hard to determine up to any additive constant. We also obtain a
+multiplicative logarithmic separation between reversible and standard pebbling
+space. This improves on the additive logarithmic separation previously known
+and could plausibly be tight, although we are not able to prove this. We leave
+as an interesting open problem whether our additive hardness of approximation
+result could be strengthened to a multiplicative bound if the computational
+resources are decreased from polynomial space to the more common setting of
+polynomial time.",2305.19104v1
+2023-06-01,Every Bit Counts in Consensus,"Consensus enables n processes to agree on a common valid L-bit value, despite
+t < n/3 processes being faulty and acting arbitrarily. A long line of work has
+been dedicated to improving the worst-case communication complexity of
+consensus in partial synchrony. This has recently culminated in the worst-case
+word complexity of O(n^2). However, the worst-case bit complexity of the best
+solution is still O(n^2 L + n^2 kappa) (where kappa is the security parameter),
+far from the \Omega(n L + n^2) lower bound. The gap is significant given the
+practical use of consensus primitives, where values typically consist of
+batches of large size (L > n).
+  This paper shows how to narrow the aforementioned gap while achieving optimal
+linear latency. Namely, we present a new algorithm, DARE (Disperse, Agree,
+REtrieve), that improves upon the O(n^2 L) term via a novel dispersal
+primitive. DARE achieves O(n^{1.5} L + n^{2.5} kappa) bit complexity, an
+effective sqrt{n}-factor improvement over the state-of-the-art (when L > n
+kappa). Moreover, we show that employing heavier cryptographic primitives,
+namely STARK proofs, allows us to devise DARE-Stark, a version of DARE which
+achieves the near-optimal bit complexity of O(n L + n^2 poly(kappa)). Both DARE
+and DARE-Stark achieve optimal O(n) latency.",2306.00431v2
+2023-06-12,Accountability Infrastructure: How to implement limits on platform optimization to protect population health,"Attention capitalism has generated design processes and product development
+decisions that prioritize platform growth over all other considerations. To the
+extent limits have been placed on these incentives, interventions have
+primarily taken the form of content moderation. While moderation is important
+for what we call ""acute harms,"" societal-scale harms -- such as negative
+effects on mental health and social trust -- require new forms of institutional
+transparency and scientific investigation, which we group under the term
+accountability infrastructure.
+  This is not a new problem. In fact, there are many conceptual lessons and
+implementation approaches for accountability infrastructure within the history
+of public health. After reviewing these insights, we reinterpret the societal
+harms generated by technology platforms through reference to public health. To
+that end, we present a novel mechanism design framework and practical
+measurement methods for that framework. The proposed approach is iterative and
+built into the product design process, and is applicable for both
+internally-motivated (i.e. self regulation by companies) and
+externally-motivated (i.e. government regulation) interventions for a range of
+societal problems, including mental health.
+  We aim to help shape a research agenda of principles for the design of
+mechanisms around problem areas on which there is broad consensus and a firm
+base of support. We offer constructive examples and discussion of potential
+implementation methods related to these topics, as well as several new data
+illustrations for potential effects of exposure to online content.",2306.07443v1
+2023-06-16,Microlayer in nucleate boiling seen as Landau-Levich film with dewetting and evaporation,"Both experimental and theoretical studies on the microscale and fast physical
+phenomena occurring during the growth of vapor bubbles in nucleate pool boiling
+are reported. The focus is on the liquid film of micrometric thickness
+(``microlayer'') that can form between the heater and the liquid-vapor
+interface of a bubble on the millisecond time scale. The microlayer strongly
+affects the macroscale heat transfer and is thus important to be understood. It
+is shown that the microlayer can be seen as the Landau-Levich film deposited by
+the bubble foot edge during its receding when the bubble grows. The microlayer
+profile measured with white-light interferometry, the temperature distribution
+over the heater, and the bubble shape were observed with synchronized
+high-speed cameras. The microlayer consists of two regions: a ridge near the
+contact line followed by a longer and flatter part. The ridge could not be
+measured because of the intrinsic limitation of interferometry, which is
+analyzed. The simulations show that the ridge grows over time due to collection
+of liquid at contact line receding, the theoretical dynamics of which agrees
+with the experiment. The flatter part of the microlayer is bumped and its
+physical origin is explained.",2306.09838v1
+2023-06-20,High frequency oscillations in spin-torque nano oscillator due to bilinear coupling,"Exchange coupling in an interfacial context is crucial for spin-torque nano
+oscillator (STNO) that consists of a non-magnetic spacer which is alloyed with
+a ferromagnetic material. Currently, investigations on the dynamics of the free
+layer magnetization and frequency enhancement in the STNO with bilinear
+coupling are still being actively pursued. In the present work, we investigate
+the dynamics of the STNO in the presence of bilinear coupling but in the
+absence of an external magnetic field by analyzing the associated
+Landau-Lifshitz-Gilbert-Sloncewski(LLGS) equation, and consequently the impact
+of the bilinear coupling on the dynamics of the magnetization of the free layer
+is studied. It is observed that the frequency of the oscillations in the
+magnetization component along the direction of the pinned layer polarization
+can be enhanced above 300 GHz by positive bilinear coupling and up to around 30
+GHz by negative bilinear coupling. We further reveal a transition from in-plane
+to out-of-plane precession both for positive and negative bi-linear couplings.
+We also analyze the switching of the magnetization for different values of
+current and bilinear coupling. Our detailed investigations of STNO with
+bilinear coupling aim at the possibilities of high-frequency devices by
+considering the applied current and bilinear coupling in the absence of a
+magnetic field.",2306.11415v1
+2023-06-20,Convolutional neural networks for large-scale dynamical modeling of itinerant magnets,"Complex spin textures in itinerant electron magnets hold promises for
+next-generation memory and information technology. The long-ranged and often
+frustrated electron-mediated spin interactions in these materials give rise to
+intriguing localized spin structures such as skyrmions. Yet, simulations of
+magnetization dynamics for such itinerant magnets are computationally difficult
+due to the need for repeated solutions to the electronic structure problems. We
+present a convolutional neural network (CNN) model to accurately and
+efficiently predict the electron-induced magnetic torques acting on local
+spins. Importantly, as the convolutional operations with a fixed kernel
+(receptive field) size naturally take advantage of the locality principle for
+many-electron systems, CNN offers a scalable machine learning approach to spin
+dynamics. We apply our approach to enable large-scale dynamical simulations of
+skyrmion phases in itinerant spin systems. By incorporating the CNN model into
+Landau-Lifshitz-Gilbert dynamics, our simulations successfully reproduce the
+relaxation process of the skyrmion phase and stabilize a skyrmion lattice in
+larger systems. The CNN model also allows us to compute the effective receptive
+fields, thus providing a systematic and unbiased method for determining the
+locality of the original electron models.",2306.11833v1
+2023-06-29,Relaxed Local Correctability from Local Testing,"We construct the first asymptotically good relaxed locally correctable codes
+with polylogarithmic query complexity, bringing the upper bound polynomially
+close to the lower bound of Gur and Lachish (SICOMP 2021). Our result follows
+from showing that a high-rate locally testable code can boost the block length
+of a smaller relaxed locally correctable code, while preserving the correcting
+radius and incurring only a modest additive cost in rate and query complexity.
+We use the locally testable code's tester to check if the amount of corruption
+in the input is low; if so, we can ""zoom-in"" to a suitable substring of the
+input and recurse on the smaller code's local corrector. Hence, iterating this
+operation with a suitable family of locally testable codes due to Dinur, Evra,
+Livne, Lubotzky, and Mozes (STOC 2022) yields asymptotically good codes with
+relaxed local correctability, arbitrarily large block length, and
+polylogarithmic query complexity.
+  Our codes asymptotically inherit the rate and distance of any locally
+testable code used in the final invocation of the operation. Therefore, our
+framework also yields nonexplicit relaxed locally correctable codes with
+polylogarithmic query complexity that have rate and distance approaching the
+Gilbert-Varshamov bound.",2306.17035v2
+2023-07-13,"Words are not Wind -- How Joint Commitment and Reputation Solve Social Dilemmas, without Repeated Interactions or Enforcement by Third Parties","Joint commitment was argued to ""make our social world"" (Gilbert, 2014) and to
+separate us from other primates. 'Joint' entails that neither of us promises
+anything, unless the other promises as well. When we need to coordinate for the
+best mutual outcome, any commitment is beneficial. However, when we are tempted
+to free-ride (i.e. in social dilemmas), commitment serves no obvious purpose.
+We show that a reputation system, which judges action in social dilemmas only
+after joint commitment, can prevent free-riding. Keeping commitments builds
+trust. We can selectively enter joint commitments with trustworthy individuals
+to ensure their cooperation (since they will now be judged). We simply do not
+commit to cooperate with those we do not trust, and hence can freely defect
+without losing the trust of others. This principle might be the reason for
+pointedly public joint commitments, such as marriage. It is especially relevant
+to our evolutionary past, in which no mechanisms existed to enforce commitments
+reliably and impartially (e.g. via a powerful and accountable government). Much
+research from anthropology, philosophy and psychology made the assumption that
+past collaborations were mutually beneficial and had little possibilities to
+free-ride, for which there is little support. Our evolutionary game theory
+approach proves that this assumption is not necessary, because free-riding
+could have been dealt with joint commitments and reputation.",2307.06898v1
+2023-07-18,Multi-Stage Cable Routing through Hierarchical Imitation Learning,"We study the problem of learning to perform multi-stage robotic manipulation
+tasks, with applications to cable routing, where the robot must route a cable
+through a series of clips. This setting presents challenges representative of
+complex multi-stage robotic manipulation scenarios: handling deformable
+objects, closing the loop on visual perception, and handling extended behaviors
+consisting of multiple steps that must be executed successfully to complete the
+entire task. In such settings, learning individual primitives for each stage
+that succeed with a high enough rate to perform a complete temporally extended
+task is impractical: if each stage must be completed successfully and has a
+non-negligible probability of failure, the likelihood of successful completion
+of the entire task becomes negligible. Therefore, successful controllers for
+such multi-stage tasks must be able to recover from failure and compensate for
+imperfections in low-level controllers by smartly choosing which controllers to
+trigger at any given time, retrying, or taking corrective action as needed. To
+this end, we describe an imitation learning system that uses vision-based
+policies trained from demonstrations at both the lower (motor control) and the
+upper (sequencing) level, present a system for instantiating this method to
+learn the cable routing task, and perform evaluations showing great performance
+in generalizing to very challenging clip placement variations. Supplementary
+videos, datasets, and code can be found at
+https://sites.google.com/view/cablerouting.",2307.08927v5
+2023-07-20,Fallout from U.S. atmospheric nuclear tests in New Mexico and Nevada (1945-1962),"One hundred and one atmospheric nuclear weapon tests were conducted between
+1945 and 1962 in the United States, resulting in widespread dispersion of
+radioactive fallout, and leading to environmental contamination and population
+exposures. Accurate assessment of the extent of fallout from nuclear weapon
+tests has been challenging in the United States and elsewhere, due to limited
+monitoring and data accessibility. Here we address this deficit by combining
+U.S. government data, high-resolution reanalyzed historical weather fields, and
+atmospheric transport modeling to reconstruct radionuclide deposition across
+the contiguous United States, with 10-kilometer spatial and one-hour temporal
+resolution for five days following detonation, from all 94 atmospheric tests
+detonated in New Mexico and Nevada with fission yields sufficient to generate
+mushroom clouds. Our analysis also includes deposition estimates for 10 days
+following the detonation of Trinity, the first ever nuclear weapon test, on
+July 16, 1945. We identify locations where radionuclide deposition
+significantly exceeded levels in areas covered by the U.S. Radiation Exposure
+Compensation Act (RECA). These findings include deposition in all 48 contiguous
+U.S. states. They provide an opportunity for re-evaluating the public health
+and environmental implications from atmospheric nuclear testing. Finally, our
+findings also speak to debates about marking the beginning of the Anthropocene
+with nuclear weapons fallout. Our deposition estimates indicate that direct
+fallout from Trinity, a plutonium device, reached Crawford Lake in Canada, the
+proposed ""golden spike"" site marking the beginning of the Anthropocene epoch,
+starting on July 20, 1945.",2307.11040v1
+2023-07-23,Characterizing non-Markovian Quantum Process by Fast Bayesian Tomography,"To push gate performance to levels beyond the thresholds for quantum error
+correction, it is important to characterize the error sources occurring on
+quantum gates. However, the characterization of non-Markovian error poses a
+challenge to current quantum process tomography techniques. Fast Bayesian
+Tomography (FBT) is a self-consistent gate set tomography protocol that can be
+bootstrapped from earlier characterization knowledge and be updated in
+real-time with arbitrary gate sequences. Here we demonstrate how FBT allows for
+the characterization of key non-Markovian error processes. We introduce two
+experimental protocols for FBT to diagnose the non-Markovian behavior of
+two-qubit systems on silicon quantum dots. To increase the efficiency and
+scalability of the experiment-analysis loop, we develop an online FBT software
+stack. To reduce experiment cost and analysis time, we also introduce a native
+readout method and warm boot strategy. Our results demonstrate that FBT is a
+useful tool for probing non-Markovian errors that can be detrimental to the
+ultimate realization of fault-tolerant operation on quantum computing.",2307.12452v2
+2023-07-27,Open Problems and Fundamental Limitations of Reinforcement Learning from Human Feedback,"Reinforcement learning from human feedback (RLHF) is a technique for training
+AI systems to align with human goals. RLHF has emerged as the central method
+used to finetune state-of-the-art large language models (LLMs). Despite this
+popularity, there has been relatively little public work systematizing its
+flaws. In this paper, we (1) survey open problems and fundamental limitations
+of RLHF and related methods; (2) overview techniques to understand, improve,
+and complement RLHF in practice; and (3) propose auditing and disclosure
+standards to improve societal oversight of RLHF systems. Our work emphasizes
+the limitations of RLHF and highlights the importance of a multi-faceted
+approach to the development of safer AI systems.",2307.15217v2
+2023-08-03,"Predicting Ki67, ER, PR, and HER2 Statuses from H&E-stained Breast Cancer Images","Despite the advances in machine learning and digital pathology, it is not yet
+clear if machine learning methods can accurately predict molecular information
+merely from histomorphology. In a quest to answer this question, we built a
+large-scale dataset (185538 images) with reliable measurements for Ki67, ER,
+PR, and HER2 statuses. The dataset is composed of mirrored images of H\&E and
+corresponding images of immunohistochemistry (IHC) assays (Ki67, ER, PR, and
+HER2. These images are mirrored through registration. To increase reliability,
+individual pairs were inspected and discarded if artifacts were present (tissue
+folding, bubbles, etc). Measurements for Ki67, ER and PR were determined by
+calculating H-Score from image analysis. HER2 measurement is based on binary
+classification: 0 and 1+ (IHC scores representing a negative subset) vs 3+ (IHC
+score positive subset). Cases with IHC equivocal score (2+) were excluded. We
+show that a standard ViT-based pipeline can achieve prediction performances
+around 90% in terms of Area Under the Curve (AUC) when trained with a proper
+labeling protocol. Finally, we shed light on the ability of the trained
+classifiers to localize relevant regions, which encourages future work to
+improve the localizations. Our proposed dataset is publicly available:
+https://ihc4bc.github.io/",2308.01982v1
+2023-08-06,Unravelling metallic contaminants in complex polyimide heterostructures using deep ultraviolet spectroscopic ellipsometry,"Metallic contaminants in complex heterostructures are important topics due to
+their significant roles in determining physical properties as well as device
+performance. Heterostructures of polyimide via on Al pad and Cu redistribution
+layer (RDL) on polyimide have shown exotic properties and are important for
+advanced semiconductor packaging systems. One main problem is significant
+leakage current variations, which affect the performance of the devices, yet
+the origin is far from understood. Furthermore, metal contaminations would
+occur at the buried interfaces and it is particularly challenging to probe
+them. Until now, the electronic and optical properties of complex polyimide
+heterostructures and the roles of metallic contaminants, especially in the deep
+ultraviolet (DUV) have not been studied extensively. Herewith, using
+spectroscopic ellipsometry (SE) in a broad DUV range supported with
+finite-difference time-domain (FDTD) calculations, we determine optical
+properties of contaminants with various concentrations and reveal their
+influence on device performance of under-bump vias and redistribution layer
+(RDL) architectures. The complex dielectric function shows varying
+contamination levels and different metals responsible for chip performance.
+Metallic contaminants are found embedded within 50 nm in the polyimide and
+different metals are distinguishable with varying concentrations, in agreement
+with contact measurements in highly complex structures. Our result shows the
+potency of spectroscopic ellipsometry in the DUV and paves the way for
+non-destructive, advanced quality control and metrology applications in
+integrated advanced electronics packaging systems.",2308.03015v1
+2023-08-14,Nanoelectromechanical control of spin-photon interfaces in a hybrid quantum system on chip,"Atom-like defects or color centers (CC's) in nanostructured diamond are a
+leading platform for optically linked quantum technologies, with recent
+advances including memory-enhanced quantum communication, multi-node quantum
+networks, and spin-mediated generation of photonic cluster states. Scaling to
+practically useful applications motivates architectures meeting the following
+criteria: C1 individual optical addressing of spin qubits; C2 frequency tuning
+of CC spin-dependent optical transitions; C3 coherent spin control in CC ground
+states; C4 active photon routing; C5 scalable manufacturability; and C6 low
+on-chip power dissipation for cryogenic operations. However, no architecture
+meeting C1-C6 has thus far been demonstrated. Here, we introduce a hybrid
+quantum system-on-chip (HQ-SoC) architecture that simultaneously achieves
+C1-C6. Key to this advance is the realization of piezoelectric strain control
+of diamond waveguide-coupled tin vacancy centers to meet C2 and C3, with
+ultra-low power dissipation necessary for C6. The DC response of our device
+allows emitter transition tuning by over 20 GHz, while the large frequency
+range (exceeding 2 GHz) enables low-power AC control. We show acoustic
+manipulation of integrated tin vacancy spins and estimate single-phonon
+coupling rates over 1 kHz in the resolved sideband regime. Combined with
+high-speed optical routing with negligible static hold power, this HQ-SoC
+platform opens the path to scalable single-qubit control with optically
+mediated entangling gates.",2308.07161v1
+2023-08-23,MOFO: MOtion FOcused Self-Supervision for Video Understanding,"Self-supervised learning (SSL) techniques have recently produced outstanding
+results in learning visual representations from unlabeled videos. Despite the
+importance of motion in supervised learning techniques for action recognition,
+SSL methods often do not explicitly consider motion information in videos. To
+address this issue, we propose MOFO (MOtion FOcused), a novel SSL method for
+focusing representation learning on the motion area of a video, for action
+recognition. MOFO automatically detects motion areas in videos and uses these
+to guide the self-supervision task. We use a masked autoencoder which randomly
+masks out a high proportion of the input sequence; we force a specified
+percentage of the inside of the motion area to be masked and the remainder from
+outside. We further incorporate motion information into the finetuning step to
+emphasise motion in the downstream task. We demonstrate that our motion-focused
+innovations can significantly boost the performance of the currently leading
+SSL method (VideoMAE) for action recognition. Our method improves the recent
+self-supervised Vision Transformer (ViT), VideoMAE, by achieving +2.6%, +2.1%,
++1.3% accuracy on Epic-Kitchens verb, noun and action classification,
+respectively, and +4.7% accuracy on Something-Something V2 action
+classification. Our proposed approach significantly improves the performance of
+the current SSL method for action recognition, indicating the importance of
+explicitly encoding motion in SSL.",2308.12447v2
+2023-08-25,Thermal effect on microwave pulse driven magnetization switching of Stoner particle,"Recently it has been demonstrated that the cosine chirp microwave pulse
+(CCMP) is capable of achieving fast and energy-efficient magnetization-reversal
+of a nanoparticle with zero-Temperature. However, we investigate the finite
+temperature, $T$ effect on the CCMP-driven magnetization reversal using the
+framework of the stochastic Landau Lifshitz Gilbert equation. At finite
+Temperature, we obtain the CCMP-driven fast and energy-efficient reversal and
+hence estimate the maximal temperature, $T_{max}$ at which the magnetization
+reversal is valid. $T_{max}$ increases with increasing the nanoparticle
+cross-sectional area/shape anisotropy up to a certain value, and afterward
+$T_{max}$ decreases with the further increment of nanoparticle cross-sectional
+area/shape anisotropy. This is because of demagnetization/shape anisotropy
+field opposes the magnetocrystalline anisotropy, i.e., reduces the energy
+barrier which separates the two stable states. For smaller cross-sectional
+area/shape anisotropy, the controlling parameters of CCMP show decreasing trend
+with temperature. We also find that with the increment easy-plane
+shape-anisotropy, the required initial frequency of CCMP significantly reduces.
+For the larger volume of nanoparticles, the parameters of CCMP remains constant
+for a wide range of temperature which are desired for the device application.
+Therefore, The above findings might be useful to realize the CCMP-driven fast
+and energy-efficient magnetization reversal in realistic conditions.",2308.13124v1
+2023-09-04,Impact of electrostatic crosstalk on spin qubits in dense CMOS quantum dot arrays,"Quantum processors based on integrated nanoscale silicon spin qubits are a
+promising platform for highly scalable quantum computation. Current CMOS spin
+qubit processors consist of dense gate arrays to define the quantum dots,
+making them susceptible to crosstalk from capacitive coupling between a dot and
+its neighbouring gates. Small but sizeable spin-orbit interactions can transfer
+this electrostatic crosstalk to the spin g-factors, creating a dependence of
+the Larmor frequency on the electric field created by gate electrodes
+positioned even tens of nanometers apart. By studying the Stark shift from tens
+of spin qubits measured in nine different CMOS devices, we developed a
+theoretical frawework that explains how electric fields couple to the spin of
+the electrons in increasingly complex arrays, including those electric
+fluctuations that limit qubit dephasing times $T_2^*$. The results will aid in
+the design of robust strategies to scale CMOS quantum technology.",2309.01849v1
+2023-09-05,Connectivity and interference in device-to-device networks in Poisson-Voronoi cities,"To study the overall connectivity in device-to-device networks in cities, we
+incorporate a signal-to-interference-plus-noise connectivity model into a
+Poisson-Voronoi tessellation model representing the streets of a city. Relays
+are located at crossroads (or street intersections), whereas (user) devices are
+scattered along streets. Between any two adjacent relays, we assume data can be
+transmitted either directly between the relays or through users, given they
+share a common street. Our simulation results reveal that the network
+connectivity is ensured when the density of users (on the streets) exceeds a
+certain critical value. But then the network connectivity disappears when the
+user density exceeds a second critical value. The intuition is that for longer
+streets, where direct relay-to-relay communication is not possible, users are
+needed to transmit data between relays, but with too many users the
+interference becomes too strong, eventually reducing the overall network
+connectivity. This observation on the user density evokes previous results
+based on another wireless network model, where transmitter-receivers were
+scattered across the plane. This effect disappears when interference is removed
+from the model, giving a variation of the classic Gilbert model and recalling
+the lesson that neglecting interference in such network models can give overly
+optimistic results. For physically reasonable model parameters, we show that
+crowded streets (with more than six users on a typical street) lead to a sudden
+drop in connectivity. We also give numerical results outlining a relationship
+between the user density and the strength of any interference reduction
+techniques.",2309.02137v2
+2023-09-16,On non-expandable cross-bifix-free codes,"A cross-bifix-free code of length $n$ over $\mathbb{Z}_q$ is defined as a
+non-empty subset of $\mathbb{Z}_q^n$ satisfying that the prefix set of each
+codeword is disjoint from the suffix set of every codeword. Cross-bifix-free
+codes have found important applications in digital communication systems. One
+of the main research problems on cross-bifix-free codes is to construct
+cross-bifix-free codes as large as possible in size. Recently, Wang and Wang
+introduced a family of cross-bifix-free codes $S_{I,J}^{(k)}(n)$, which is a
+generalization of the classical cross-bifix-free codes studied early by
+Lvenshtein, Gilbert and Chee {\it et al.}. It is known that $S_{I,J}^{(k)}(n)$
+is nearly optimal in size and $S_{I,J}^{(k)}(n)$ is non-expandable if $k=n-1$
+or $1\leq k<n/2$. In this paper, we first show that $S_{I,J}^{(k)}(n)$ is
+non-expandable if and only if $k=n-1$ or $1\leq k<n/2$, thereby improving the
+results in [Chee {\it et al.}, IEEE-TIT, 2013] and [Wang and Wang, IEEE-TIT,
+2022]. We then construct a new family of cross-bifix-free codes
+$U^{(t)}_{I,J}(n)$ to expand $S_{I,J}^{(k)}(n)$ such that the resulting larger
+code $S_{I,J}^{(k)}(n)\bigcup U^{(t)}_{I,J}(n)$ is a non-expandable
+cross-bifix-free code whenever $S_{I,J}^{(k)}(n)$ is expandable. Finally, we
+present an explicit formula for the size of $S_{I,J}^{(k)}(n)\bigcup
+U^{(t)}_{I,J}(n)$.",2309.08915v1
+2023-09-21,Real-time feedback protocols for optimizing fault-tolerant two-qubit gate fidelities in a silicon spin system,"Recently, several groups have demonstrated two-qubit gate fidelities in
+semiconductor spin qubit systems above 99%. Achieving this regime of
+fault-tolerant compatible high fidelities is nontrivial and requires exquisite
+stability and precise control over the different qubit parameters over an
+extended period of time. This can be done by efficiently calibrating qubit
+control parameters against different sources of micro- and macroscopic noise.
+Here, we present several single- and two-qubit parameter feedback protocols,
+optimised for and implemented in state-of-the-art fast FPGA hardware.
+Furthermore, we use wavelet-based analysis on the collected feedback data to
+gain insight into the different sources of noise in the system. Scalable
+feedback is an outstanding challenge and the presented implementation and
+analysis gives insight into the benefits and drawbacks of qubit parameter
+feedback, as feedback related overhead increases. This work demonstrates a
+pathway towards robust qubit parameter feedback and systematic noise analysis,
+crucial for mitigation strategies towards systematic high-fidelity qubit
+operation compatible with quantum error correction protocols.",2309.12541v1
+2023-09-21,Spatio-temporal correlations of noise in MOS spin qubits,"In quantum computing, characterising the full noise profile of qubits can aid
+the efforts towards increasing coherence times and fidelities by creating error
+mitigating techniques specific to the type of noise in the system, or by
+completely removing the sources of noise. Spin qubits in MOS quantum dots are
+exposed to noise originated from the complex glassy behaviour of two-level
+fluctuators, leading to non-trivial correlations between qubit properties both
+in space and time. With recent engineering progress, large amounts of data are
+being collected in typical spin qubit device experiments, and it is beneficiary
+to explore data analysis options inspired from fields of research that are
+experienced in managing large data sets, examples include astrophysics, finance
+and climate science. Here, we propose and demonstrate wavelet-based analysis
+techniques to decompose signals into both frequency and time components to gain
+a deeper insight into the sources of noise in our systems. We apply the
+analysis to a long feedback experiment performed on a state-of-the-art
+two-qubit system in a pair of SiMOS quantum dots. The observed correlations
+serve to identify common microscopic causes of noise, as well as to elucidate
+pathways for multi-qubit operation with a more scalable feedback system.",2309.12542v2
+2023-09-29,Glioma subtype classification from histopathological images using in-domain and out-of-domain transfer learning: An experimental study,"We provide in this paper a comprehensive comparison of various transfer
+learning strategies and deep learning architectures for computer-aided
+classification of adult-type diffuse gliomas. We evaluate the generalizability
+of out-of-domain ImageNet representations for a target domain of
+histopathological images, and study the impact of in-domain adaptation using
+self-supervised and multi-task learning approaches for pretraining the models
+using the medium-to-large scale datasets of histopathological images. A
+semi-supervised learning approach is furthermore proposed, where the fine-tuned
+models are utilized to predict the labels of unannotated regions of the whole
+slide images (WSI). The models are subsequently retrained using the
+ground-truth labels and weak labels determined in the previous step, providing
+superior performance in comparison to standard in-domain transfer learning with
+balanced accuracy of 96.91% and F1-score 97.07%, and minimizing the
+pathologist's efforts for annotation. Finally, we provide a visualization tool
+working at WSI level which generates heatmaps that highlight tumor areas; thus,
+providing insights to pathologists concerning the most informative parts of the
+WSI.",2309.17223v1
+2023-10-13,Midpoint geometric integrators for inertial magnetization dynamics,"We consider the numerical solution of the inertial version of
+Landau-Lifshitz-Gilbert equation (iLLG), which describes high-frequency
+nutation on top of magnetization precession due to angular momentum relaxation.
+The iLLG equation defines a higher-order nonlinear dynamical system with very
+different nature compared to the classical LLG equation, requiring twice as
+many degrees of freedom for space-time discretization. It exhibits essential
+conservation properties, namely magnetization amplitude preservation,
+magnetization projection conservation, and a balance equation for generalized
+free energy, leading to a Lyapunov structure (i.e. the free energy is a
+decreasing function of time) when the external magnetic field is constant in
+time. We propose two second-order numerical schemes for integrating the iLLG
+dynamics over time, both based on implicit midpoint rule. The first scheme
+unconditionally preserves all the conservation properties, making it the
+preferred choice for simulating inertial magnetization dynamics. However, it
+implies doubling the number of unknowns, necessitating significant changes in
+numerical micromagnetic codes and increasing computational costs especially for
+spatially inhomogeneous dynamics simulations. To address this issue, we present
+a second time-stepping method that retains the same computational cost as the
+implicit midpoint rule for classical LLG dynamics while unconditionally
+preserving magnetization amplitude and projection. Special quasi-Newton
+techniques are developed for solving the nonlinear system of equations required
+at each time step due to the implicit nature of both time-steppings. The
+numerical schemes are validated on analytical solution for macrospin terahertz
+frequency response and the effectiveness of the second scheme is demonstrated
+with full micromagnetic simulation of inertial spin waves propagation in a
+magnetic thin-film.",2310.09043v1
+2023-10-28,Einstein-de Haas torque as a discrete spectroscopic probe allows nanomechanical measurement of a magnetic resonance,"The Einstein-de Haas (EdH) effect is a fundamental, mechanical consequence of
+any temporal change of magnetism in an object. EdH torque results from
+conserving the object's total angular momentum: the angular momenta of all the
+specimen's magnetic moments, together with its mechanical angular momentum.
+Although the EdH effect is usually small and difficult to observe, it increases
+in magnitude with detection frequency. We explore the frequency-dependence of
+EdH torque for a thin film permalloy microstructure by employing a ladder of
+flexural beam modes (with five distinct resonance frequencies spanning from 3
+to 208 MHz) within a nanocavity optomechanical torque sensor via magnetic
+hysteresis curves measured at mechanical resonances. At low DC fields the
+gyrotropic resonance of a magnetic vortex spin texture overlaps the 208 MHz
+mechanical mode. The massive EdH mechanical torques arising from this
+co-resonance yield a fingerprint of vortex core pinning and depinning in the
+sample. The experimental results are discussed in relation to mechanical
+torques predicted from both macrospin (at high DC magnetic field) and
+finite-difference solutions to the Landau-Lifshitz-Gilbert (LLG) equation. A
+global fit of the LLG solutions to the frequency-dependent data reveals a
+statistically significant discrepancy between the experimentally observed and
+simulated torque phase behaviours at spin texture transitions that can be
+reduced through the addition of a time constant to the conversion between
+magnetic cross-product torque and mechanical torque, constrained by experiment
+to be in the range of 0.5 - 4 ns.",2310.18546v2
+2023-10-31,Ensemble models outperform single model uncertainties and predictions for operator-learning of hypersonic flows,"High-fidelity computational simulations and physical experiments of
+hypersonic flows are resource intensive. Training scientific machine learning
+(SciML) models on limited high-fidelity data offers one approach to rapidly
+predict behaviors for situations that have not been seen before. However,
+high-fidelity data is itself in limited quantity to validate all outputs of the
+SciML model in unexplored input space. As such, an uncertainty-aware SciML
+model is desired. The SciML model's output uncertainties could then be used to
+assess the reliability and confidence of the model's predictions. In this
+study, we extend a DeepONet using three different uncertainty quantification
+mechanisms: mean-variance estimation, evidential uncertainty, and ensembling.
+The uncertainty aware DeepONet models are trained and evaluated on the
+hypersonic flow around a blunt cone object with data generated via
+computational fluid dynamics over a wide range of Mach numbers and altitudes.
+We find that ensembling outperforms the other two uncertainty models in terms
+of minimizing error and calibrating uncertainty in both interpolative and
+extrapolative regimes.",2311.00060v2
+2023-11-11,Double-Free-Layer Stochastic Magnetic Tunnel Junctions with Synthetic Antiferromagnets,"Stochastic magnetic tunnel junctions (sMTJ) using low-barrier nanomagnets
+have shown promise as fast, energy-efficient, and scalable building blocks for
+probabilistic computing. Despite recent experimental and theoretical progress,
+sMTJs exhibiting the ideal characteristics necessary for probabilistic bits
+(p-bit) are still lacking. Ideally, the sMTJs should have (a) voltage bias
+independence preventing read disturbance (b) uniform randomness in the
+magnetization angle between the free layers, and (c) fast fluctuations without
+requiring external magnetic fields while being robust to magnetic field
+perturbations. Here, we propose a new design satisfying all of these
+requirements, using double-free-layer sMTJs with synthetic antiferromagnets
+(SAF). We evaluate the proposed sMTJ design with experimentally benchmarked
+spin-circuit models accounting for transport physics, coupled with the
+stochastic Landau-Lifshitz-Gilbert equation for magnetization dynamics. We find
+that the use of low-barrier SAF layers reduces dipolar coupling, achieving
+uncorrelated fluctuations at zero-magnetic field surviving up to diameters
+exceeding ($D\approx 100$ nm) if the nanomagnets can be made thin enough
+($\approx 1$-$2$ nm). The double-free-layer structure retains bias-independence
+and the circular nature of the nanomagnets provides near-uniform randomness
+with fast fluctuations. Combining our full sMTJ model with advanced transistor
+models, we estimate the energy to generate a random bit as $\approx$ 3.6 fJ,
+with fluctuation rates of $\approx$ 3.3 GHz per p-bit. Our results will guide
+the experimental development of superior stochastic magnetic tunnel junctions
+for large-scale and energy-efficient probabilistic computation for problems
+relevant to machine learning and artificial intelligence.",2311.06642v2
+2023-11-14,Toxicity Detection is NOT all you Need: Measuring the Gaps to Supporting Volunteer Content Moderators,"Extensive efforts in automated approaches for content moderation have been
+focused on developing models to identify toxic, offensive, and hateful content
+with the aim of lightening the load for moderators. Yet, it remains uncertain
+whether improvements on those tasks have truly addressed moderators' needs in
+accomplishing their work. In this paper, we surface gaps between past research
+efforts that have aimed to provide automation for aspects of content moderation
+and the needs of volunteer content moderators, regarding identifying violations
+of various moderation rules. To do so, we conduct a model review on Hugging
+Face to reveal the availability of models to cover various moderation rules and
+guidelines from three exemplar forums. We further put state-of-the-art LLMs to
+the test, evaluating how well these models perform in flagging violations of
+platform rules from one particular forum. Finally, we conduct a user survey
+study with volunteer moderators to gain insight into their perspectives on
+useful moderation models. Overall, we observe a non-trivial gap, as missing
+developed models and LLMs exhibit moderate to low performance on a significant
+portion of the rules. Moderators' reports provide guides for future work on
+developing moderation assistant models.",2311.07879v2
+2023-11-14,All Byzantine Agreement Problems are Expensive,"Byzantine agreement, arguably the most fundamental problem in distributed
+computing, operates among n processes, out of which t < n can exhibit arbitrary
+failures. The problem states that all correct (non-faulty) processes must
+eventually decide (termination) the same value (agreement) from a set of
+admissible values defined by the proposals of the processes (validity).
+Depending on the exact version of the validity property, Byzantine agreement
+comes in different forms, from Byzantine broadcast to strong and weak
+consensus, to modern variants of the problem introduced in today's blockchain
+systems. Regardless of the specific flavor of the agreement problem, its
+communication cost is a fundamental metric whose improvement has been the focus
+of decades of research. The Dolev-Reischuk bound, one of the most celebrated
+results in distributed computing, proved 40 years ago that, at least for
+Byzantine broadcast, no deterministic solution can do better than Omega(t^2)
+exchanged messages in the worst case. Since then, it remained unknown whether
+the quadratic lower bound extends to seemingly weaker variants of Byzantine
+agreement. This paper answers the question in the affirmative, closing this
+long-standing open problem. Namely, we prove that any non-trivial agreement
+problem requires Omega(t^2) messages to be exchanged in the worst case. To
+prove the general lower bound, we determine the weakest Byzantine agreement
+problem and show, via a novel indistinguishability argument, that it incurs
+Omega(t^2) exchanged messages.",2311.08060v2
+2023-11-21,Nonparametric variable importance for time-to-event outcomes with application to prediction of HIV infection,"In survival analysis, complex machine learning algorithms have been
+increasingly used for predictive modeling. Given a collection of features
+available for inclusion in a predictive model, it may be of interest to
+quantify the relative importance of a subset of features for the prediction
+task at hand. In particular, in HIV vaccine trials, participant baseline
+characteristics are used to predict the probability of infection over the
+intended follow-up period, and investigators may wish to understand how much
+certain types of predictors, such as behavioral factors, contribute toward
+overall predictiveness. Time-to-event outcomes such as time to infection are
+often subject to right censoring, and existing methods for assessing variable
+importance are typically not intended to be used in this setting. We describe a
+broad class of algorithm-agnostic variable importance measures for prediction
+in the context of survival data. We propose a nonparametric efficient
+estimation procedure that incorporates flexible learning of nuisance
+parameters, yields asymptotically valid inference, and enjoys
+double-robustness. We assess the performance of our proposed procedure via
+numerical simulations and analyze data from the HVTN 702 study to inform
+enrollment strategies for future HIV vaccine trials.",2311.12726v2
+2023-11-29,Atmospheric Escape From Three Terrestrial Planets in the L 98-59 System,"A critically important process affecting the climate evolution and potential
+habitability of an exoplanet is atmospheric escape, in which high-energy
+radiation from a star drives the escape of hydrogen atoms and other light
+elements from a planet's atmosphere. L 98-59 is a benchmark system for studying
+such atmospheric processes, with three transiting terrestrial-size planets
+receiving Venus-like instellations (4-25 S$_\oplus$) from their M3 host star.
+We use the VPLanet model to simulate the evolution of the L 98-59 system and
+the atmospheric escape of its inner three small planets, given different
+assumed initial water quantities. We find that, regardless of their initial
+water content, all three planets accumulate significant quantities of oxygen
+due to efficient water photolysis and hydrogen loss. All three planets also
+receive enough XUV flux to drive rapid water loss, which considerably affects
+their developing climates and atmospheres. Even in scenarios of low initial
+water content, our results suggest that the James Webb Space Telescope (JWST)
+will be sensitive to observations of retained oxygen on the L 98-59 planets in
+its future scheduled observations, with planets b and c being the most likely
+targets to possess an extended atmosphere. Our results constrain the
+atmospheric evolution of these small rocky planets, and they provide context
+for current and future observations of the L 98-59 system to generalize our
+understanding of multi-terrestrial planet systems.",2312.00062v1
+2023-12-05,A complex-projected Rayleigh quotient iteration for targeting interior eigenvalues,"We introduce a new Projected Rayleigh Quotient Iteration aimed at improving
+the convergence behaviour of classic Rayleigh Quotient iteration (RQI) by
+incorporating approximate information about the target eigenvector at each
+step. While classic RQI exhibits local cubic convergence for Hermitian
+matrices, its global behaviour can be unpredictable, whereby it may converge to
+an eigenvalue far away from the target, even when started with accurate initial
+conditions. This problem is exacerbated when the eigenvalues are closely
+spaced. The key idea of the new algorithm is at each step to add a
+complex-valued projection to the original matrix (that depends on the current
+eigenvector approximation), such that the unwanted eigenvalues are lifted into
+the complex plane while the target stays close to the real line, thereby
+increasing the spacing between the target eigenvalue and the rest of the
+spectrum. Making better use of the eigenvector approximation leads to more
+robust convergence behaviour and the new method converges reliably to the
+correct target eigenpair for a significantly wider range of initial vectors
+than does classic RQI. We prove that the method converges locally cubically and
+we present several numerical examples demonstrating the improved global
+convergence behaviour. In particular, we apply it to compute eigenvalues in a
+band-gap spectrum of a Sturm-Liouville operator used to model photonic crystal
+fibres, where the target and unwanted eigenvalues are closely spaced. The
+examples show that the new method converges to the desired eigenpair even when
+the eigenvalue spacing is very small, often succeeding when classic RQI fails.",2312.02847v2
+2023-12-14,On statistical zonostrophic instability and the effect of magnetic fields,"Zonal flows are mean flows in the east-west direction, which are ubiquitous
+on planets, and can be formed through 'zonostrophic instability': within
+turbulence or random waves, a weak large-scale zonal flow can grow
+exponentially to become prominent. In this paper, we study the statistical
+behaviour of the zonostrophic instability and the effect of magnetic fields. We
+use a stochastic white noise forcing to drive random waves, and study the
+growth of a mean flow in this random system. The dispersion relation for the
+growth rate of the expectation of the mean flow is derived, and properties of
+the instability are discussed. In the limits of weak and strong magnetic
+diffusivity, the dispersion relation reduces to manageable expressions, which
+provide clear insights into the effect of the magnetic field and scaling laws
+for the threshold of instability. The magnetic field mainly plays a stabilising
+role and thus impedes the formation of the zonal flow, but under certain
+conditions it can also have destabilising effects. Numerical simulation of the
+stochastic flow is performed to confirm the theory. Results indicate that the
+magnetic field can significantly increase the randomness of the zonal flow. It
+is found that the zonal flow of an individual realisation may behave very
+differently from the expectation. For weak magnetic diffusivity and moderate
+magnetic field strengths, this leads to considerable variation of the outcome,
+that is whether zonostrophic instability takes place or not in individual
+realisations.",2312.08905v1
+2023-12-19,Towards a theta correspondence in families for type II dual pairs,"Let $R$ be a commutative $\mathbb{Z}[1/p]$-algebra, let $m \leq n$ be
+positive integers, and let $G_n=\text{GL}_n(F)$ and $G_m=\text{GL}_m(F)$ where
+$F$ is a $p$-adic field. The Weil representation is the smooth $R[G_n\times
+G_m]$-module $C_c^{\infty}(\text{Mat}_{n\times m}(F),R)$ with the action
+induced by matrix multiplication. When $R=\mathbb{C}$ or is any algebraically
+closed field of banal characteristic compared to $G_n$ and $G_m$, the local
+theta correspondence holds by the work of Howe and M\'inguez. At the level of
+supercuspidal support, we interpret the theta correspondence as a morphism of
+varieties $\theta_R$, which we describe as an explicit closed immersion. For
+arbitrary $R$, we construct a canonical ring homomorphism $\theta^\#_{R} :
+\mathfrak{Z}_{R}(G_n)\to \mathfrak{Z}_{R}(G_m)$ that controls the action of the
+center $\mathfrak{Z}_{R}(G_n)$ of the category of smooth $R[G_n]$-modules on
+the Weil representation. We use the rank filtration of the Weil representation
+to first obtain $\theta_{\mathbb{Z}[1/p]}^\#$, then obtain $\theta^\#_R$ for
+arbitrary $R$ by proving $\mathfrak{Z}_R(G_n)$ is compatible with scalar
+extension. In particular, the map $\text{Spec}(\mathfrak{Z}_R(G_m))\to
+\text{Spec}(\mathfrak{Z}_R(G_n))$ induced by $\theta_R^\#$ recovers $\theta_R$
+in the $R=\mathbb{C}$ case and in the banal case. We use gamma factors to prove
+$\theta_R^\#$ is surjective for any $R$. Finally, we describe $\theta^\#_R$ in
+terms of the moduli space of Langlands parameters and use this description to
+give an alternative proof of surjectivity in the tamely ramified case.",2312.12031v1
+2023-12-19,Microscopic theory of current-induced skyrmion transport and its application in disordered spin textures,"Magnetic skyrmions hold great promise for realizing compact and stable memory
+devices that can be manipulated at very low energy costs via electronic current
+densities. In this work, we extend a recently introduced method to describe
+classical skyrmion textures coupled to dynamical itinerant electrons. In this
+scheme, the electron dynamics is described via nonequilibrium Green's functions
+(NEGF) within the generalized Kadanoff-Baym ansatz, and the classical spins are
+treated via the Landau-Lifshitz-Gilbert equation. The framework is here
+extended to open systems, by the introduction of a non-interacting
+approximation to the collision integral of NEGF. This, in turn, allows us to
+perform computations of the real-time response of skyrmions to electronic
+currents in large quantum systems coupled to electronic reservoirs, which
+exhibit a linear scaling in the number of time steps. We use this approach to
+investigate how electronic spin currents and dilute spin disorder affects
+skyrmion transport and the skyrmion Hall drift. Our results show that the
+skyrmion dynamics is sensitive to the specific form of spin disorder, such that
+different disorder configurations leads to qualitatively different skyrmion
+trajectories for the same applied bias. This sensitivity arises from the local
+spin dynamics around the magnetic impurities, a feature that is expected not to
+be well captured by phenomenological or spin-only descriptions. At the same
+time, our findings illustrate the potential of engineering microscopic impurity
+patterns to steer skyrmion trajectories.",2312.12201v1
+2024-01-09,Characterization of two fast-turnaround dry dilution refrigerators for scanning probe microscopy,"Low-temperature scanning probe microscopes (SPMs) are critical for the study
+of quantum materials and quantum information science. Due to the rising costs
+of helium, cryogen-free cryostats have become increasingly desirable. However,
+they typically suffer from comparatively worse vibrations than cryogen-based
+systems, necessitating the understanding and mitigation of vibrations for SPM
+applications. Here we demonstrate the construction of two cryogen-free dilution
+refrigerator SPMs with minimal modifications to the factory default and we
+systematically characterize their vibrational performance. We measure the
+absolute vibrations at the microscope stage with geophones, and use both
+microwave impedance microscopy and a scanning single electron transistor to
+independently measure tip-sample vibrations. Additionally, we implement
+customized filtering and thermal anchoring schemes, and characterize the
+cooling power at the scanning stage and the tip electron temperature. This work
+serves as a reference to researchers interested in cryogen-free SPMs, as such
+characterization is not standardized in the literature or available from
+manufacturers.",2401.04373v1
+2024-01-11,Micromagnetic simulations of the size dependence of the Curie temperature in ferromagnetic nanowires and nanolayers,"We solve the Landau-Lifshitz-Gilbert equation in the finite-temperature
+regime, where thermal fluctuations are modeled by a random magnetic field whose
+variance is proportional to the temperature. By rescaling the temperature
+proportionally to the computational cell size $\Delta x$ ($T \to T\,\Delta
+x/a_{\text{eff}}$, where $a_{\text{eff}}$ is the lattice constant) [M. B. Hahn,
+J. Phys. Comm., 3:075009, 2019], we obtain Curie temperatures $T_{\text{C}}$
+that are in line with the experimental values for cobalt, iron and nickel. For
+finite-sized objects such as nanowires (1D) and nanolayers (2D), the Curie
+temperature varies with the smallest size $d$ of the system. We show that the
+difference between the computed finite-size $T_{\text{C}}$ and the bulk
+$T_{\text{C}}$ follows a power-law of the type: $(\xi_0/d)^\lambda$, where
+$\xi_0$ is the correlation length at zero temperature, and $\lambda$ is a
+critical exponent. We obtain values of $\xi_0$ in the nanometer range, also in
+accordance with other simulations and experiments. The computed critical
+exponent is close to $\lambda=2$ for all considered materials and geometries.
+This is the expected result for a mean-field approach, but slightly larger than
+the values observed experimentally.",2401.05722v1
+2024-01-24,"How AI Ideas Affect the Creativity, Diversity, and Evolution of Human Ideas: Evidence From a Large, Dynamic Experiment","Exposure to large language model output is rapidly increasing. How will
+seeing AI-generated ideas affect human ideas? We conducted an experiment (800+
+participants, 40+ countries) where participants viewed creative ideas that were
+from ChatGPT or prior experimental participants and then brainstormed their own
+idea. We varied the number of AI-generated examples (none, low, or high
+exposure) and if the examples were labeled as 'AI' (disclosure). Our dynamic
+experiment design -- ideas from prior participants in an experimental condition
+are used as stimuli for future participants in the same experimental condition
+-- mimics the interdependent process of cultural creation: creative ideas are
+built upon prior ideas. Hence, we capture the compounding effects of having
+LLMs 'in the culture loop'. We find that high AI exposure (but not low AI
+exposure) did not affect the creativity of individual ideas but did increase
+the average amount and rate of change of collective idea diversity. AI made
+ideas different, not better. There were no main effects of disclosure. We also
+found that self-reported creative people were less influenced by knowing an
+idea was from AI, and that participants were more likely to knowingly adopt AI
+ideas when the task was difficult. Our findings suggest that introducing AI
+ideas into society may increase collective diversity but not individual
+creativity.",2401.13481v1
+2024-01-31,Multimaterial Inkjet Printing of Mechanochromic Materials,"Inkjet printing technology achieves the precise deposition of liquid-phase
+materials via the digitally controlled formation of picoliter-sized droplets.
+Beyond graphical printing, inkjet printing has been employed for the deposition
+of separated drops on surfaces or the formation of continuous layers, which
+allows to construct materials gradients or periodic features that provide
+enhanced functionalities. Here, we explore the use of multinozzle,
+drop-on-demand piezoelectric inkjet technology for the manufacturing of
+mechanochromic materials, i.e., materials that change their color or
+fluorescence in response to mechanical deformation. To accomplish this,
+suitable polyurethane polymers of differing hardness grades were tested with a
+range of organic solvents to formulate low-viscosity, inkjet-printable
+solutions. Following their rheological characterization, two solutions
+comprised of ""soft"" and ""hard"" polyurethanes were selected for in-depth study.
+The solutions were imbibed with a mechanochromic additive to yield fluorescent
+inks, which were either dropcast onto polymeric substrates or printed to form
+checkerboard patterns of alternating hardness using a lab-built, multimaterial
+inkjet platform. Fluorescence imaging and spectroscopy were used to identify
+different hardness grades in the dropcast and printed materials, as well as to
+monitor the responses of these gradient materials to mechanical deformation.
+The insights gained in this study are expected to facilitate the development of
+inkjet-printable, mechanochromic polymer materials for a wide range of
+applications.",2401.17758v2
+2024-01-11,Resonant inelastic x-ray scattering in warm-dense Fe compounds beyond the SASE FEL resolution limit,"Resonant inelastic x-ray scattering (RIXS) is a widely used spectroscopic
+technique, providing access to the electronic structure and dynamics of atoms,
+molecules, and solids. However, RIXS requires a narrow bandwidth x-ray probe to
+achieve high spectral resolution. The challenges in delivering an energetic
+monochromated beam from an x-ray free electron laser (XFEL) thus limit its use
+in few-shot experiments, including for the study of high energy density
+systems. Here we demonstrate that by correlating the measurements of the
+self-amplified spontaneous emission (SASE) spectrum of an XFEL with the RIXS
+signal, using a dynamic kernel deconvolution with a neural surrogate, we can
+achieve electronic structure resolutions substantially higher than those
+normally afforded by the bandwidth of the incoming x-ray beam. We further show
+how this technique allows us to discriminate between the valence structures of
+Fe and Fe$_2$O$_3$, and provides access to temperature measurements as well as
+M-shell binding energies estimates in warm-dense Fe compounds.",2402.00039v1
+2024-02-08,Trustful Coopetitive Infrastructures for the New Space Exploration Era,"In the new space economy, space agencies, large enterprises, and start-ups
+aim to launch space multi-robot systems (MRS) for various in-situ resource
+utilization (ISRU) purposes, such as mapping, soil evaluation, and utility
+provisioning. However, these stakeholders' competing economic interests may
+hinder effective collaboration on a centralized digital platform. To address
+this issue, neutral and transparent infrastructures could facilitate
+coordination and value exchange among heterogeneous space MRS. While related
+work has expressed legitimate concerns about the technical challenges
+associated with blockchain use in space, we argue that weighing its potential
+economic benefits against its drawbacks is necessary. This paper presents a
+novel architectural framework and a comprehensive set of requirements for
+integrating blockchain technology in MRS, aiming to enhance coordination and
+data integrity in space exploration missions. We explored distributed ledger
+technology (DLT) to design a non-proprietary architecture for heterogeneous MRS
+and validated the prototype in a simulated lunar environment. The analyses of
+our implementation suggest global ISRU efficiency improvements for map
+exploration, compared to a corresponding group of individually acting robots,
+and that fostering a coopetitive environment may provide additional revenue
+opportunities for stakeholders.",2402.06014v1
+2024-02-08,Designing Trustful Cooperation Ecosystems is Key to the New Space Exploration Era,"In the emerging space economy, autonomous robotic missions with specialized
+goals such as mapping and mining are gaining traction, with agencies and
+enterprises increasingly investing resources. Multirobot systems (MRS) research
+has provided many approaches to establish control and communication layers to
+facilitate collaboration from a technical perspective, such as granting more
+autonomy to heterogeneous robotic groups through auction-based interactions in
+mesh networks. However, stakeholders' competing economic interests often
+prevent them from cooperating within a proprietary ecosystem. Related work
+suggests that distributed ledger technology (DLT) might serve as a mechanism
+for enterprises to coordinate workflows and trade services to explore space
+resources through a transparent, reliable, non-proprietary digital platform. We
+challenge this perspective by pointing to the core technical weaknesses of
+blockchains, in particular, increased energy consumption, low throughput, and
+full transparency through redundancy. Our objective is to advance the
+discussion in a direction where the benefits of DLT from an economic
+perspective are weighted against the drawbacks from a technical perspective. We
+finally present a possible DLT-driven heterogeneous MRS for map exploration to
+study the opportunities for economic collaboration and competitiveness.",2402.06036v1
+2024-02-29,Magnon spectrum of altermagnets: Time-dependent matrix product states vs. linearized Holstein-Primakoff calculations unravelling spontaneous magnon decay,"The energy-momentum dispersion of magnons, viewed as noninteracting and
+infinitely long-lived quasiparticles describing collective low-energy
+excitations of magnetic materials, is often presented as sharp bands obtained
+from the effective quantum spin Hamiltonian, after being simplified via
+linearized Holstein-Primakoff (HP) transformations. However, magnons are prone
+to many-body interactions with other quasiparticles which can lead to their
+spontaneous decay. The magnon-magnon interactions could affect newly classified
+altermagnets. On the other hand, sharp bands of noninteracting chiral magnons
+in RuO2, as the canonical example of altermagnets, have been very recently
+predicted. Here, we employ nonperturbative numerically (quasi)exact quantum
+many-body calculations, via time-dependent matrix product states (TDMPS), to
+obtain magnon spectral function of RuO2. These calculations produce a broadened
+magnon dispersion, which overlaps with linearized HP theory sharp bands only at
+edges/center of the Brillouin zone. Substantially deviating otherwise.
+Artificially making exchange interaction within two sublattices of RuO2 closer
+in value forces these two spectra to overlap, thereby explaining the origin of
+the failure of linearized HP theory. Such features translate into the
+difference between their respective density of states, which we also compute
+and which could be tested by Raman scattering experiments. Finally, we employ
+popular Landau-Lifshitz-Gilbert (LLG) equation-based classical atomistic spin
+dynamics (ASD) simulations to obtain dynamical structure factor and extract
+magnon spectrum from it at finite temperature. Despite including magnon-magnon
+interactions via nonlinearity of LLG equation, ASD simulations cannot fully
+match the TDMPS-computed magnon spectrum due to nonclassical effects harbored
+by altermagnets.",2402.19433v1
+2024-03-07,Controllable Skyrmion Islands in a Moiré Magnet,"Antiferromagnetic(AFM) skyrmions have been in the spotlight as ideal
+topological magnetic bits. Although they are topologically protected, they do
+not exhibit the skyrmion Hall effect unlike the ferromagnetic ones. Thus, AFM
+skyrmions are considered to provide a better control of the skyrmion's motion
+due to the absence of the skyrmion Magnus effect. In this work, we propose a
+possible realization of controllable AFM skyrmions in a twisted Moir\'e magnet.
+The tunability of Moir\'e materials is not only a good platform for the
+provision of rich phases, but also for the stabilization of skyrmion phase. We
+investigate the ground state of twisted bilayer AFM system by solving the
+Landau-Lifshitz-Gilbert equation in a continuum model. We show that the AFM
+skyrmions are stabilized even in the absence of the external/dipolar magnetic
+field, as a consequence of the interplay of interlayer coupling,
+Dzyaloshinskii-Moriya (DM) interaction and Ising anisotropy. More
+interestingly, due to the magnetoelectric effect, the application of an
+external electric field locally stabilizes the skyrmions in the twisted bilayer
+AFM systems, even in the absence of DM interaction. It also allows the skyrmion
+helicity to change continuously when both the DM interaction and an electric
+field are present. We show the phase diagram with respect to the strength of
+interlayer coupling, the DM interaction and an electric field. Our results
+suggest the possibility of using AFM skyrmions as stable, controllable
+topological magnetic bits.",2403.04208v1
+2024-03-08,A Data Augmentation Pipeline to Generate Synthetic Labeled Datasets of 3D Echocardiography Images using a GAN,"Due to privacy issues and limited amount of publicly available labeled
+datasets in the domain of medical imaging, we propose an image generation
+pipeline to synthesize 3D echocardiographic images with corresponding ground
+truth labels, to alleviate the need for data collection and for laborious and
+error-prone human labeling of images for subsequent Deep Learning (DL) tasks.
+The proposed method utilizes detailed anatomical segmentations of the heart as
+ground truth label sources. This initial dataset is combined with a second
+dataset made up of real 3D echocardiographic images to train a Generative
+Adversarial Network (GAN) to synthesize realistic 3D cardiovascular Ultrasound
+images paired with ground truth labels. To generate the synthetic 3D dataset,
+the trained GAN uses high resolution anatomical models from Computed Tomography
+(CT) as input. A qualitative analysis of the synthesized images showed that the
+main structures of the heart are well delineated and closely follow the labels
+obtained from the anatomical models. To assess the usability of these synthetic
+images for DL tasks, segmentation algorithms were trained to delineate the left
+ventricle, left atrium, and myocardium. A quantitative analysis of the 3D
+segmentations given by the models trained with the synthetic images indicated
+the potential use of this GAN approach to generate 3D synthetic data, use the
+data to train DL models for different clinical tasks, and therefore tackle the
+problem of scarcity of 3D labeled echocardiography datasets.",2403.05384v1
+2024-03-10,Dynamical generation of skyrmion and bimeron crystals by a circularly polarized electric field in frustrated magnets,"A skyrmion crystal (SkX) has attracted much attention in condensed matter
+physics, since topologically nontrivial structures induce fascinating physical
+phenomena. The SkXs have been experimentally observed in a variety of
+materials, where the Zeeman coupling to the static magnetic field plays an
+important role in the formation of the SkXs. In this study, we theoretically
+propose another route to generate the SkXs by using a circularly polarized
+electric field. We investigate a non-equilibrium steady state in a classical
+frustrated Heisenberg magnet under the circularly polarized electric field,
+where the electric field is coupled to the electric polarization via the
+spin-current mechanism. By numerically solving the Landau-Lifshitz-Gilbert
+equation at zero temperature, we show that the electric field radiation
+generates a SkX with a high topological number in the high-frequency regime,
+where the sign of the skyrmion number is fixed to be negative (positive) under
+the left (right) circularly polarized field. The intense electric field melts
+these SkXs and generates isolated skyrmions. We clarify that the microscopic
+origin is effective electric-field-induced three-spin interactions by adopting
+the high-frequency expansion in the Floquet formalism. Furthermore, we find
+that the electric field radiation generates another type of SkXs, a bimeron
+crystal, in the low-frequency regime. Our results provide a way to generate the
+SkXs and control the topology by the circularly polarized electric field.",2403.06118v1
+2024-03-12,Flexible Non-intrusive Dynamic Instrumentation for WebAssembly,"A key strength of managed runtimes over hardware is the ability to gain
+detailed insight into the dynamic execution of programs with instrumentation.
+Analyses such as code coverage, execution frequency, tracing, and debugging,
+are all made easier in a virtual setting. As a portable, low-level bytecode,
+WebAssembly offers inexpensive in-process sandboxing with high performance. Yet
+to date, Wasm engines have not offered much insight into executing programs,
+supporting at best bytecode-level stepping and basic source maps, but no
+instrumentation capabilities. In this paper, we show the first non-intrusive
+dynamic instrumentation system for WebAssembly in the open-source Wizard
+Research Engine. Our innovative design offers a flexible, complete hierarchy of
+instrumentation primitives that support building high-level, complex analyses
+in terms of low-level, programmable probes. In contrast to emulation or machine
+code instrumentation, injecting probes at the bytecode level increases
+expressiveness and vastly simplifies the implementation by reusing the engine's
+JIT compiler, interpreter, and deoptimization mechanism rather than building
+new ones. Wizard supports both dynamic instrumentation insertion and removal
+while providing consistency guarantees, which is key to composing multiple
+analyses without interference. We detail a fully-featured implementation in a
+high-performance multi-tier Wasm engine, show novel optimizations specifically
+designed to minimize instrumentation overhead, and evaluate performance
+characteristics under load from various analyses. This design is well-suited
+for production engine adoption as probes can be implemented to have no impact
+on production performance when not in use.",2403.07973v1
+2024-03-13,Highly confined epsilon-near-zero- and surface-phonon polaritons in SrTiO3 membranes,"Recent theoretical studies have suggested that transition metal perovskite
+oxide membranes can enable surface phonon polaritons in the infrared range with
+low loss and much stronger subwavelength confinement than bulk crystals. Such
+modes, however, have not been experimentally observed so far. Here, using a
+combination of far-field Fourier-transform infrared (FTIR) spectroscopy and
+near-field synchrotron infrared nanospectroscopy (SINS) imaging, we study the
+phonon-polaritons in a 100 nm thick freestanding crystalline membrane of SrTiO3
+transferred on metallic and dielectric substrates. We observe a
+symmetric-antisymmetric mode splitting giving rise to epsilon-near-zero and
+Berreman modes as well as highly confined (by a factor of 10) propagating
+phonon polaritons, both of which result from the deep-subwavelength thickness
+of the membranes. Theoretical modeling based on the analytical finite-dipole
+model and numerical finite-difference methods fully corroborate the
+experimental results. Our work reveals the potential of oxide membranes as a
+promising platform for infrared photonics and polaritonics.",2403.08500v1
+2024-03-18,Lattice QCD estimates of thermal photon production from the QGP,"Thermal photons produced in heavy-ion collision experiments are an important
+observable for understanding quark-gluon plasma (QGP). The thermal photon rate
+from the QGP at a given temperature can be calculated from the spectral
+function of the vector current correlator. Extraction of the spectral function
+from the lattice correlator is known to be an ill-conditioned problem, as there
+is no unique solution for a spectral function for a given lattice correlator
+with statistical errors. The vector current correlator, on the other hand,
+receives a large ultraviolet contribution from the vacuum, which makes the
+extraction of the thermal photon rate difficult from this channel. We therefore
+consider the difference between the transverse and longitudinal part of the
+spectral function, only capturing the thermal contribution to the current
+correlator, simplifying the reconstruction significantly. The lattice
+correlator is calculated for light quarks in quenched QCD at $T=470~$MeV ($\sim
+1.5\, T_c$), as well as in 2+1 flavor QCD at $T=220~$MeV ($\sim 1.2 \, T_{pc}$)
+with $m_{\pi}=320$ MeV. In order to quantify the non-perturbative effects, the
+lattice correlator is compared with the corresponding
+$\text{NLO}+\text{LPM}^{\text{LO}}$ estimate of correlator. The reconstruction
+of the spectral function is performed in several different frameworks, ranging
+from physics-informed models of the spectral function to more general models in
+the Backus-Gilbert method and Gaussian Process regression. We find that the
+resulting photon rates agree within errors.",2403.11647v1
+2024-03-20,Optimal Risk-Sensitive Scheduling Policies for Remote Estimation of Autoregressive Markov Processes,"We design scheduling policies that minimize a risk-sensitive cost criterion
+for a remote estimation setup. Since risk-sensitive cost objective takes into
+account not just the mean value of the cost, but also higher order moments of
+its probability distribution, the resulting policy is robust to changes in the
+underlying system's parameters. The setup consists of a sensor that observes a
+discrete-time autoregressive Markov process, and at each time $t$ decides
+whether or not to transmit its observations to a remote estimator using an
+unreliable wireless communication channel after encoding these observations
+into data packets. We model the communication channel as a Gilbert-Elliott
+channel \cite{10384144}. Sensor probes the channel \cite{laourine2010betting}
+and hence knows the channel state at each time $t$ before making scheduling
+decision. The scheduler has to minimize the expected value of the exponential
+of the finite horizon cumulative cost that is sum of the following two
+quantities (i) the cumulative transmission power consumed, (ii) the cumulative
+squared estimator error. We pose this dynamic optimization problem as a Markov
+decision process (MDP), in which the system state at time $t$ is composed of
+(i) the instantaneous error $\Delta(t):= x(t)-a\hat{x}(t-1)$, where
+$x(t),\hat{x}(t-1)$ are the system state and the estimate at time $t,t-1$
+respectively, and (ii) the channel state $c(t)$. We show that there exists an
+optimal policy that has a threshold structure, i.e., at each time $t$, for each
+possible channel state $c$, there is a threshold $\D\ust(c)$ such that if the
+current channel state is $c$, then it transmits only when the error $\D(t)$
+exceeds $\D\ust(c)$.",2403.13898v1
+2024-03-27,"The Correlations of Scene Complexity, Workload, Presence, and Cybersickness in a Task-Based VR Game","This investigation examined the relationships among scene complexity,
+workload, presence, and cybersickness in virtual reality (VR) environments.
+Numerous factors can influence the overall VR experience, and existing research
+on this matter is not yet conclusive, warranting further investigation. In this
+between-subjects experimental setup, 44 participants engaged in the Pendulum
+Chair game, with half exposed to a simple scene with lower optic flow and lower
+familiarity, and the remaining half to a complex scene characterized by higher
+optic flow and greater familiarity. The study measured the dependent variables
+workload, presence, and cybersickness and analyzed their correlations.
+Equivalence testing was also used to compare the simple and complex
+environments. Results revealed that despite the visible differences between the
+environments, within the 10% boundaries of the maximum possible value for
+workload and presence, and 13.6% of the maximum SSQ value, a statistically
+significant equivalence was observed between the simple and complex scenes.
+Additionally, a moderate, negative correlation emerged between workload and SSQ
+scores. The findings suggest two key points: (1) the nature of the task can
+mitigate the impact of scene complexity factors such as optic flow and
+familiarity, and (2) the correlation between workload and cybersickness may
+vary, showing either a positive or negative relationship.",2403.19019v1
+2024-03-28,Long-range Phase Coherence and Tunable Second Order $φ_0$-Josephson Effect in a Dirac Semimetal $1T-PtTe_2$,"Superconducting diode effects have recently attracted much attention for
+their potential applications in superconducting logic circuits. Several
+mechanisms such as magneto-chiral effects, finite momentum Cooper pairing,
+asymmetric edge currents have been proposed to give rise to a supercurrent
+diode effect in different materials. In this work, we establish the presence of
+a large intrinsic Josephson diode effect in a type-II Dirac semimetal
+$1T-PtTe_2$ facilitated by its helical spin-momentum locking and distinguish it
+from other extrinsic effects. The magnitude of the Josephson diode effect is
+shown to be directly correlated to the large second-harmonic component of the
+supercurrent that is induced by the significant contribution of the topological
+spin-momentum locked states that promote coherent Andreev processes in the
+junction. We denote such junctions, where the relative phase between the two
+harmonics corresponding to charge transfers of $2e$ and $4e$ can be tuned by a
+magnetic field, as second order ${\phi}_0$-junctions. The direct correspondence
+between the second harmonic supercurrent component and the diode effect in
+$1T-PtTe_2$ junctions makes topological semimetals with high transparency an
+ideal platform to study and implement the Josephson diode effect, while also
+enabling further research on higher order supercurrent transport in Josephson
+junctions.",2403.19445v1
+1997-04-08,A complementary group technique for the resolution of the outer multiplicity problem of SU(n): (II) A recoupling approach to the solution of SU(3)\supset U(2) reduced Wigner coefficients,"A general procedure for the derivation of SU(3)\supset U(2) reduced Wigner
+coefficients for the coupling (\lambda_{1}\mu_{1})\times
+(\lambda_{2}\mu_{2})\downarrow (\lambda\mu)^{\eta}, where \eta is the outer
+multiplicity label needed in the decomposition, is proposed based on a
+recoupling approach according to the complementary group technique given in
+(I). It is proved that the non-multiplicity-free reduced Wigner coefficients of
+SU(n) are not unique with respect to canonical outer multiplicity labels, and
+can be transformed from one set of outer multiplicity labels to another. The
+transformation matrices are elements of SO(m), where m is the number of
+occurrence of the corresponding irrep (\lambda\mu) in the decomposition
+(\lambda_{1}\mu_{1})\times (\lambda_{2}\mu_{2})\downarrow (\lambda\mu). Thus, a
+kind of the reduced Wigner coefficients with multiplicity is obtained after a
+special SO(m) transformation. New features of this kind of reduced Wigner
+coefficients and the differences from the reduced Wigner coefficients with
+other choice of the multiplicity label given previously are discussed. The
+method can also be applied to the derivation of general SU(n) Wigner or reduced
+Wigner coefficients with multiplicity. Algebraic expression of another kind of
+reduced Wigner coefficients, the so-called reduced auxiliary Wigner
+coefficients for SU(3)\supset U(2), are also obtained.",9704015v1
+2008-11-03,Modeling the evolution of Gini coefficient for personal incomes in the USA between 1947 and 2005,"The evolution of Gini coefficient for personal incomes in the USA between
+1947 and 2005 is analyzed and modeled. There are several versions of personal
+income distribution (PID) provided by the US Census Bureau (US CB) for this
+period with various levels of resolution. Effectively, these PIDs result in
+different Gini coefficients due to the differences between discrete and
+continuous representations. When all persons of 15 years of age and over are
+included in the PIDs, Gini coefficient drops from 0.64 in 1947 to 0.54 in 1990.
+This effect is observed due to a significant decrease in the portion of people
+without income. For the PIDs not including persons without income, Gini
+coefficient is varying around 0.51 between 1960 and 2005 with standard
+deviation of 0.004, i.e. is in fact constant. This Gini coefficient is
+practically independent on the portion of population included in the PIDs
+according to any revision of income definitions. The driving force of the model
+describing the evolution of individual incomes (microeconomic level) and their
+aggregate value (macroeconomic level) is the change in nominal GDP per capita.
+The model accurately predicts the evolution of Gini coefficient for the PIDs
+for people with income. The model gives practically unchanged (normalized) PIDs
+and Gini coefficient between 1947 and 2005. The empirical Gini curves converge
+to the predicted one when the number of people without income decreases.
+Asymptotically, the empirical curves should collapse to the theoretical one
+when all the working age population obtains an appropriate definition of
+income. Therefore the model Gini coefficient potentially better describes true
+behavior of inequality in the USA because the definitions of income used by the
+US Census Bureau apparently fail to describe true income distribution.",0811.0356v1
+2009-09-30,Granular gas of viscoelastic particles in a homogeneous cooling state,"Kinetic properties of a granular gas of viscoelastic particles in a
+homogeneous cooling state are studied analytically and numerically. We employ
+the most recent expression for the velocity-dependent restitution coefficient
+for colliding viscoelastic particles, which allows to describe systems with
+large inelasticity. In contrast to previous studies, the third coefficient a3
+of the Sonine polynomials expansion of the velocity distribution function is
+taken into account. We observe a complicated evolution of this coefficient.
+Moreover, we find that a3 is always of the same order of magnitude as the
+leading second Sonine coefficient a2; this contradicts the existing hypothesis
+that the subsequent Sonine coefficients a2, a3 ..., are of an ascending order
+of a small parameter, characterizing particles inelasticity. We analyze
+evolution of the high-energy tail of the velocity distribution function. In
+particular, we study the time dependence of the tail amplitude and of the
+threshold velocity, which demarcates the main part of the velocity distribution
+and the high-energy part. We also study evolution of the self-diffusion
+coefficient D and explore the impact of the third Sonine coefficient on the
+self-diffusion. Our analytical predictions for the third Sonine coefficient,
+threshold velocity and the self-diffusion coefficient are in a good agreement
+with the numerical finding.",0909.5563v2
+2013-11-30,Polynomial properties of Jack connection coefficients and generalization of a result by Dénes,"This article is devoted to the computation of Jack connection coefficients, a
+generalization of the connection coefficients of two classical commutative
+subalgebras of the group algebra of the symmetric group: the class algebra and
+the double coset algebra. The connection coefficients of these two algebraic
+structures are of significant interest in the study of Schur and zonal
+polynomials as well as the irreducible characters of the symmetric group and
+the zonal spherical functions. Furthermore they play an important role in
+combinatorics as they give the number of factorizations of a permutation into a
+product of permutations with given cyclic properties. Usually studied
+separately, these two families of coefficients share strong similar properties.
+First (partially) introduced by Goulden and Jackson in 1996, Jack connection
+coefficients provide a natural unified approach closely related to the theory
+of Jack polynomials, a family of bases in the ring of symmetric functions
+indexed by a parameter \alpha that generalizes both Schur (case \alpha = 1) and
+zonal polynomials (case \alpha = 2). Jack connection coefficients are also
+directly linked to Jack characters, a general view of the characters of the
+symmetric group and the zonal spherical functions. Goulden and Jackson
+conjectured that these coefficients are polynomials in \alpha with nice
+combinatorial properties, the so-called Matchings-Jack conjecture. In this
+paper, we use the theory of Jack symmetric functions and the Laplace Beltrami
+operator to show the polynomial properties of Jack connection coefficients in
+some important cases. We also provide explicit formulations including notably a
+generalization of a classical formula of D\'enes for the number of minimal
+factorizations of a permutation into transpositions.",1312.0120v3
+2019-02-14,A Consistent Reduced Network for HCN Chemistry in Early Earth and Titan Atmospheres: Quantum Calculations of Reaction Rate Coefficients,"HCN is a key ingredient for synthesizing biomolecules such as nucleobases and
+amino acids. We calculate 42 reaction rate coefficients directly involved with
+or in competition with the production of HCN in the early Earth or Titan
+atmospheres. These reactions are driven by methane and nitrogen radicals
+produced via UV photodissociation or lightning. For every reaction in this
+network, we calculate rate coefficients at 298 K using canonical variational
+transition state theory (CVT) paired with computational quantum chemistry
+simulations at the BHandHLYP/augcc-pVDZ level of theory. We also calculate the
+temperature dependence of the rate coefficients for the reactions that have
+barriers from 50 to 400 K. We present 15 new reaction rate coefficients with no
+previously known value; 93% of our calculated coefficients are within an order
+of magnitude of the nearest experimental or recommended values. Above 320 K,
+the rate coefficient for the new reaction H2CN -> HCN + H dominates. Contrary
+to experiments, we find the HCN reaction pathway, N + CH3 -> HCN + H2, to be
+inefficient and suggest that the experimental rate coefficient actually
+corresponds to an indirect pathway, through the H2CN intermediate. We present
+CVT using energies computed with density functional theory as a feasible and
+accurate method for calculating a large network of rate coefficients of
+small-molecule reactions.",1902.05574v1
+2019-05-22,Holographic OPE Coefficients from AdS Black Holes with Matters,"We study the OPE coefficients $c_{\Delta, J}$ for heavy-light scalar
+four-point functions, which can be obtained holographically from the two-point
+function of a light scalar of some non-integer conformal dimension $\Delta_L$
+in an AdS black hole. We verify that the OPE coefficient $c_{d,0}=0$ for pure
+gravity black holes, consistent with the tracelessness of the holographic
+energy-momentum tensor. We then study the OPE coefficients from black holes
+involving matter fields. We first consider general charged AdS black holes and
+we give some explicit low-lying examples of the OPE coefficients. We also
+obtain the recursion formula for the lowest-twist OPE coefficients with at most
+two current operators. For integer $\Delta_L$, although the OPE coefficients
+are not fully determined, we set up a framework to read off the coefficients
+$\gamma_{\Delta,J}$ of the $\log(z\bar{z})$ terms that are associated with the
+anomalous dimensions of the exchange operators and obtain a general formula for
+$\gamma_{\Delta,J}$. We then consider charged AdS black holes in gauged
+supergravity STU models in $D=5$ and $D=7$, and their higher-dimensional
+generalizations. The scalar fields in the STU models are conformally massless,
+dual to light operators with $\Delta_L=d-2$. We derive the linear perturbation
+of such a scalar in the STU charged AdS black holes and obtain the explicit OPE
+coefficient $c_{d-2,0}$. Finally, we analyse the asymptotic properties of
+scalar hairy AdS black holes and show how $c_{d,0}$ can be nonzero with
+exchanging scalar operators in these backgrounds.",1905.09302v2
+2020-11-10,The improved model of user similarity coefficients computation For recommendation systems,"The subject matter of the article is a model of calculating the user
+similarity coefficients of the recommendation systems. The goal is the
+development of the improved model of user similarity coefficients calculation
+for recommendation systems to optimize the time of forming recommendation
+lists. The tasks to be solved are: to investigate the probability of changing
+user preferences of a recommendation system by comparing their similarity
+coefficients in time, to investigate which distribution function describes the
+changes of similarity coefficients of users in time. The methods used are:
+graph theory, probability theory, radioactivity theory, algorithm theory.
+Conclusions. In the course of the researches, the model of user similarity
+coefficients calculating for the recommendation systems has been improved. The
+model differs from the known ones in that it takes into account the
+recalculation period of similarity coefficients for the individual user and
+average recalculation period of similarity coefficients for all users of the
+system or a specific group of users. The software has been developed, in which
+a series of experiments was conducted to test the effectiveness of the
+developed method. The conducted experiments showed that the developed method in
+general increases the quality of the recommendation system without significant
+fluctuations of Precision and Recall of the system. Precision and Recall can
+decrease slightly or increase, depending on the characteristics of the incoming
+data set. The use of the proposed solutions will increase the application
+period of the previously calculated similarity coefficients of users for the
+prediction of preferences without their recalculation and, accordingly, it will
+shorten the time of formation and issuance of recommendation lists up to 2
+times.",2011.05057v1
+2021-08-03,Generalized coefficients of the Dirichlet series,"The paper considers a method for converting a divergent Dirichlet series into
+a convergent Dirichlet series by directly converting the coefficients of the
+original series $1\rightarrow\delta_{n}(s)$ for the Riemann Zeta function. In
+the first part of the paper, we study the properties of the coefficients
+${\delta}^*_n$ of a finite Dirichlet series for approximating the Riemann Zeta
+function on the interval $\Delta{H}$. In general, the coefficients
+${\delta}^*_n$ of a finite Dirichlet series are complex numbers. The dependence
+of the coefficients ${\delta}^*_n$ of a finite Dirichlet series on the ordinal
+number of the coefficient $n$ is established, which can be set by a sigmoid,
+and for each $N$ there is a single sigmoid $\hat{\delta}_n$ and a single
+interval $\Delta{H}$ for which the condition is satisfied
+$$\Big|\sum\limits_{n}^{N}\{{\delta}^*_n- \hat\delta_n\}\Big| < \epsilon;$$ The
+second part of the paper presents the results of using the sigmoid to calculate
+the values of the generalized coefficients $\delta_{n}(s)$ of the Dirichlet
+series for the Riemann Zeta function. For the accuracy of the calculation,
+$\log_{10}(1/\epsilon)$ values of the Riemann Zeta Function by summing the
+resulting convergent Dirichlet series, the power of the imaginary part
+$t=Im(s)$ is established. Presumably, the sigmoid can be used to asymptotically
+calculate the values of the analytical continuation of any function defined by
+the Dirichlet series. Presumably, for any divergent series to which the
+generalized summation method is applicable, it is possible to find a direct
+transformation of the coefficients of the divergent series, so that the
+resulting series with the transformed coefficients will converge to the same
+function as the series of transformed partial sums.",2108.01270v1
+2022-04-26,Coefficient Mutation in the Gene-pool Optimal Mixing Evolutionary Algorithm for Symbolic Regression,"Currently, the genetic programming version of the gene-pool optimal mixing
+evolutionary algorithm (GP-GOMEA) is among the top-performing algorithms for
+symbolic regression (SR). A key strength of GP-GOMEA is its way of performing
+variation, which dynamically adapts to the emergence of patterns in the
+population. However, GP-GOMEA lacks a mechanism to optimize coefficients. In
+this paper, we study how fairly simple approaches for optimizing coefficients
+can be integrated into GP-GOMEA. In particular, we considered two variants of
+Gaussian coefficient mutation. We performed experiments using different
+settings on 23 benchmark problems, and used machine learning to estimate what
+aspects of coefficient mutation matter most. We find that the most important
+aspect is that the number of coefficient mutation attempts needs to be
+commensurate with the number of mixing operations that GP-GOMEA performs. We
+applied GP-GOMEA with the best-performing coefficient mutation approach to the
+data sets of SRBench, a large SR benchmark, for which a ground-truth underlying
+equation is known. We find that coefficient mutation can help re-discovering
+the underlying equation by a substantial amount, but only when no noise is
+added to the target variable. In the presence of noise, GP-GOMEA with
+coefficient mutation discovers alternative but similarly-accurate equations.",2204.12159v1
+2023-09-01,Interpretation of High-Dimensional Linear Regression: Effects of Nullspace and Regularization Demonstrated on Battery Data,"High-dimensional linear regression is important in many scientific fields.
+This article considers discrete measured data of underlying smooth latent
+processes, as is often obtained from chemical or biological systems.
+Interpretation in high dimensions is challenging because the nullspace and its
+interplay with regularization shapes regression coefficients. The data's
+nullspace contains all coefficients that satisfy $\mathbf{Xw}=\mathbf{0}$, thus
+allowing very different coefficients to yield identical predictions. We
+developed an optimization formulation to compare regression coefficients and
+coefficients obtained by physical engineering knowledge to understand which
+part of the coefficient differences are close to the nullspace. This nullspace
+method is tested on a synthetic example and lithium-ion battery data. The case
+studies show that regularization and z-scoring are design choices that, if
+chosen corresponding to prior physical knowledge, lead to interpretable
+regression results. Otherwise, the combination of the nullspace and
+regularization hinders interpretability and can make it impossible to obtain
+regression coefficients close to the true coefficients when there is a true
+underlying linear model. Furthermore, we demonstrate that regression methods
+that do not produce coefficients orthogonal to the nullspace, such as fused
+lasso, can improve interpretability. In conclusion, the insights gained from
+the nullspace perspective help to make informed design choices for building
+regression models on high-dimensional data and reasoning about potential
+underlying linear models, which are important for system optimization and
+improving scientific understanding.",2309.00564v2
+2024-03-06,Inverse resolution of spatially varying diffusion coefficient using Physics-Informed neural networks,"Resolving the diffusion coefficient is a key element in many biological and
+engineering systems, including pharmacological drug transport and fluid
+mechanics analyses. Additionally, these systems often have spatial variation in
+the diffusion coefficient which must be determined, such as for injectable
+drug-eluting implants into heterogeneous tissues. Unfortunately, obtaining the
+diffusion coefficient from images in such cases is an inverse problem with only
+discrete data points. The development of a robust method that can work with
+such noisy and ill-posed datasets to accurately determine spatially-varying
+diffusion coefficients is of great value across a large range of disciplines.
+Here, we developed an inverse solver that uses physics informed neural networks
+(PINNs) to calculate spatially-varying diffusion coefficients from numerical
+and experimental image data in varying biological and engineering applications.
+The residual of the transient diffusion equation for a concentration field is
+minimized to find the diffusion coefficient. The robustness of the method as an
+inverse solver was tested using both numerical and experimental datasets. The
+predictions show good agreement with both the numerical and experimental
+benchmarks; an error of less than 6.31% was obtained against all numerical
+benchmarks, while the diffusion coefficient calculated in experimental datasets
+matches the appropriate ranges of other reported literature values. Our work
+demonstrates the potential of using PINNs to resolve spatially-varying
+diffusion coefficients, which may aid a wide-range of applications, such as
+enabling better-designed drug-eluting implants for regenerative medicine or
+oncology fields.",2403.03970v1
+1997-10-02,Single-Particle Diffusion-Coefficient on Surfaces with Ehrlich-Schwoebel-Barriers,"The diffusion coefficient of single particles in the presence of
+Ehrlich-Schwoebel barriers (ESB)is considered. An exact expression is given for
+the diffusion coefficient on linear chains with random arrangements of ESB. The
+results are extended to surfaces having ESB with uniform extension in one or
+both directions. All results are verified by Monte Carlo simulations.",9710026v1
+2001-06-19,Antitrace maps and light transmission coefficients for a generalized Fibonacci multilayers,"By using antitrace map method, we investigate the light transmission for a
+generalized Fibonacci multilayers. Analytical results are obtained for
+transmission coefficients in some special cases. We find that the transmission
+coefficients possess two-cycle property or six-cycle property. The cycle
+properties of the trace and antitrace are also obtained.",0106378v1
+2005-10-01,$κ$-generalization of Stirling approximation and multinominal coefficients,"Stirling approximation of the factorials and multinominal coefficients are
+generalized based on the one-parameter ($\kappa$) deformed functions introduced
+by Kaniadakis [Phys. Rev. E \textbf{66} (2002) 056125]. We have obtained the
+relation between the $\kappa$-generalized multinominal coefficients and the
+$\kappa$-entropy by introducing a new $\kappa$-product operation.",0510018v1
+1998-09-29,Computation of the improvement coefficient $c_{sw}$ to 1-loop with improved gluon actions,"The clover coefficient $\csw$ is computed at one loop order of perturbation
+theory for improved gluon actions including six-link loops. The O(a)
+improvement coefficients for the dimension three isovector composite operators
+bilinear in the quark fields are also calculated.",9809179v1
+2001-02-12,Resummed coefficient function for the shape function,"We present a leading evaluation of the resummed coefficient function for the
+shape function. It is also shown that the coefficient function is
+short-distance-dominated. Our results allow relating the shape function
+computed on the lattice to the physical QCD distributions.",0102138v1
+2007-02-21,Transport coefficients of Relativistic Causal Hydrodynamics for Hadrons,"We investigate coefficients in the Israel-Stewart's causal hydrodynamics and
+discuss the way to calculate them with a microscopic theory. Based on the
+hadro-molecular simulation based on an event generator URASiMA, we evaluate the
+coefficients for a hot and dense hadronic fluid.",0702220v2
+1992-05-25,Operator Coefficients for Composite Operators in the $(φ^4)_4$ Theory,"In a previous paper we derived a relation between the operator product
+coefficients and anomalous dimensions. We explore this relation in the
+$(\phi^4)_4$ theory and compute the coefficient functions in the products of
+$\phi^2$ and $\phi^4$ to first order in the parameter $\lambda$. The
+calculation results in two-loop beta functions.",9205084v1
+1995-01-10,The Heat Kernel Coefficients to the Matrix Schrödinger Operator,"The heat kernel coefficients $H_k$ to the Schr\""odinger operator with a
+matrix potential are investigated. We present algorithms and explicit
+expressions for the Taylor coefficients of the $H_k$. Special terms are
+discussed, and for the one-dimensional case some improved algorithms are
+derived.",9501026v1
+1995-01-16,Heat-kernel coefficients of the Laplace operator on the 3-dimensional ball,"We consider the heat-kernel expansion of the massive Laplace operator on the
+three dimensional ball with Dirichlet boundary conditions. Using this example,
+we illustrate a very effective scheme for the calculation of an (in principle)
+arbitrary number of heat-kernel coefficients for the case where the basis
+functions are known. New results for the coefficients $B_{\frac 5 2},...,B_5$
+are presented.",9501064v1
+2000-11-10,Asymptotic expansion coefficients of the heat kernel in Riemann-Cartan space,"By applying the covariant Taylor expansion method, the fifth lower
+coefficients the asymptotic expansion of the heat kernel associated with a
+fermion of spin 1/2 in Riemann-Cartan space are manifestly given. These
+coefficients in Riemann-Cartan space is derived from those obtained in
+Riemannian space by simple replacements.",0011082v1
+2006-02-22,Eliminating the CPT-Odd f Coefficient from the Lorentz-Violating Standard Model Extension,"The fermionic f coefficient in the Lorentz-violating standard model extension
+presents a puzzle. Thus far, no observable quantity that depends upon f has
+ever been found. We show that this is because f is actually unnecessary. It has
+absolutely no effects at leading order and can be completely absorbed into
+other coefficients of the theory by a redefinition of the field.",0602235v1
+2006-11-22,Friction Coefficient for Quarks in Supergravity Duals,"We study quarks moving in strongly-coupled plasmas that have supergravity
+duals. We compute the friction coefficient of strings dual to such quarks for
+general static supergravity backgrounds near the horizon. Our results also show
+that a previous conjecture on the bound has to be modified and higher friction
+coefficients can be achieved.",0611235v1
+1995-02-09,A generalization of the binomial coefficients,"We pose the question of what is the best generalization of the factorial and
+the binomial coefficient. We give several examples, derive their combinatorial
+properties, and demonstrate their interrelationships.
+  On cherche ici \`a d\'eterminer est la meilleure g\'en\'eralisation possible
+des factorielles et des coefficients du bin\^oome. On s'interesse \`a plusieurs
+exemples, \`a leurs propri\'et\'es combinatoires, et aux differentes relations
+qu'ils mettent en jeu.",9502218v1
+2001-03-27,Symbolic Evaluation of Coefficients in Airy-type Asymptotic Expansions,"Computer algebra algorithms are developed for evaluating the coefficients in
+Airy-type asymptotic expansions that are obtained from integrals with a large
+parameter. The coefficients are defined from recursive schemes obtained from
+integration by parts. An application is given for the Weber parabolic cylinder
+function.",0103184v1
+2001-05-17,A Characterization of the Heat Kernel Coefficients,"We consider the asymptotic expansion of the heat kernel of a generalized
+Laplacian for $t\to 0^+$ and characterize the coefficients $a_k$ of this
+expansion by a natural intertwining property. In particular we will give a
+closed formula for the infinite order jet of these coefficients on the diagonal
+in terms of the local expressions of the powers of the given generalized
+Laplacian in normal coordinates.",0105144v1
+2004-01-30,The leading coefficient of certain Kazhdan-Lusztig polynomials of the permutation group $S_n$,"In this paper we show that the leading coefficient $\mu(y,w)$ of certain
+Kazhdan-Lusztig polynomials $P_{y,w}$ of the permutation group $\mathfrak S_n$
+of 1,2,...,n are not greater than 1. More precisely, we show that the leading
+coefficients $\mu(y,w)$ are not greater than 1 whenever $a(y)< a(w)$, where $a:
+\mathfrak S_n\to\mathbf N$ is the function defined by Lusztig.",0401430v1
+2005-01-12,A q-Analog of Dual Sequences with Applications,"In the present paper combinatorial identities involving q-dual sequences or
+polynomials with coefficients q-dual sequences are derived. Further,
+combinatorial identities for q-binomial coefficients(Gaussian coefficients),
+q-Stirling numbers and q-Bernoulli numbers and polynomials are deduced.",0501186v4
+2005-06-14,Combinatorial Interpretations of the q-Faulhaber and q-Salie Coefficients,"Recently, Guo and Zeng discovered two families of polynomials featuring in a
+q-analogue of Faulhaber's formula for the sums of powers and a q-analogue of
+Gessel-Viennot's formula involving Salie's coefficients for the alternating
+sums of powers. In this paper, we show that these are polynomials with
+symmetric, nonnegative integral coefficients by refining Gessel-Viennot's
+combinatorial interpretations.",0506274v1
+2005-06-22,Linearization coefficients of Bessel polynomials,"We prove positivity results about linearization and connection coefficients
+for Bessel polynomials. The proof is based on a recursion formula and explicit
+formulas for the coefficients in special cases. The result implies that the
+distribution of a convex combination of independent Student-t random variables
+with arbitrary odd degrees of freedom has a density which is a convex
+combination of certain Student-t densities with odd degrees of freedom.",0506458v1
+2005-12-06,Two-scale extensions for non-periodic coefficients,"We consider non-homogeneous media with properties which can be characterized
+by rapidly oscillated coefficients. For such coefficients we define a notion of
+two-scale extension, present several ways to construct two-scale extensions,
+discuss their properties and relation to homogenization",0512123v1
+2006-01-08,Khovanov homology for virtual links with arbitrary coefficients,"We construct explicitly the Khovanov homology theory for virtual links with
+arbitrary coefficients by using the twisted coefficients method. This method
+also works for constructing Khovanov homology for ``non-oriented virtual
+knots'' in the sense of Viro, in particular, for knots in ${\bf R}P^{3}$.",0601152v3
+2006-03-03,Orthogonal polynomials with exponentially decaying recursion coefficients,"We review recent results on necessary and sufficient conditions for measures
+on $\mathbb{R}$ and $\partial\mathbb{D}$ to yield exponential decay of the
+recursion coefficients of the corresponding orthogonal polynomials. We include
+results on the relation of detailed asymptotics of the recursion coefficients
+to detailed analyticity of the measures. We present an analog of Carmona's
+formula for OPRL. A major role is played by the Szego and Jost functions.",0603099v1
+2006-06-28,Some characterizations of the spherical harmonics coefficients for isotropic random fields,"In this paper we provide some simple characterizations for the spherical
+harmonics coefficients of an isotropic random field on the sphere. The main
+result is a characterization of isotropic gaussian fields through independence
+of the coefficients of their development in spherical harmonics.",0606709v1
+2007-01-31,Irreducibility of hypersurfaces,"Given a polynomial P in several variables over an algebraically closed field,
+we show that except in some special cases that we fully describe, if one
+coefficient is allowed to vary, then the polynomial is irreducible for all but
+at most deg(P)^2-1 values of the coefficient. We more generally handle the
+situation where several specified coefficients vary.",0701919v1
+2007-03-19,Meromorphic differentials with twisted coefficients on compact Riemann surfaces,"This note is to concern a generalization to the case of twisted coefficients
+of the classical theory of Abelian differentials on a compact Riemann surface.
+We apply the Dirichlet's principle to a modified energy functional to show the
+existence of differentials with twisted coefficients of the second and third
+kinds under a suitable assumption on residues.",0703542v1
+1999-12-23,Fundamental solutions to elliptic equations with discontinuous senior coefficients and an inequlity for these solutions,"Asymptotic formula is derived for the behavior of the fundamental solution of
+the second-order elliptic self-adjoint operator with a piecewise-smooth
+coefficient in front of the senior derivatives near the discontinuity surface
+of the coefficient. Applications to inverse problems are discussed.",9912017v1
+2006-08-28,Coefficients and terms of the liquid drop model and mass formula,"The coefficients of different combinations of terms of the liquid drop model
+have been determined by a least square fitting procedure to the experimental
+atomic masses. The nuclear masses can also be reproduced using a Coulomb radius
+taking into account the increase of the ratio $R\_0/A^{1/3}$ with increasing
+mass, the fitted surface energy coefficient remaining around 18 MeV.",0608064v1
+2001-02-12,High-precision calculations of van der Waals coefficients for heteronuclear alkali-metal dimers,"Van der Waals coefficients for the heteronuclear alkali-metal dimers of Li,
+Na, K, Rb, Cs, and Fr are calculated using relativistic ab initio methods
+augmented by high-precision experimental data. We argue that the uncertainties
+in the coefficients are unlikely to exceed about 1%.",0102030v1
+2002-11-11,Recursive Weak- and Strong Coupling Expansions in a Cosine Potential,"For the Cos(2x)-Potential the coefficients of the weak- and strong coupling
+perturbation series of the ground state energy are constructed recursively.
+They match the well-known expansion coefficients of the Mathieu equation's
+characteristic values. However presently there is no physically intuitive
+method to extract the coefficients of the strong coupling series from those of
+the weak one. The standard rule while giving exellent results for the
+anharmonic oscillator fails completely in this case.",0211057v1
+2007-05-25,Parabolic equations with measurable coefficients in $L_p$-spaces with mixed norms,"The unique solvability of parabolic equations in Sobolev spaces with mixed
+norms is presented. The second order coefficients (except $a^{11}$) are assumed
+to be only measurable in time and one spatial variable, and VMO in the other
+spatial variables. The coefficient $a^{11}$ is measurable in one spatial
+variable and VMO in the other variables.",0705.3808v1
+2007-05-29,About construction of orthogonal wavelets with compact support and with scaling coefficient N,"In this paper a simple method of construction of scaling function $\phi (x)$
+and orthogonal wavelets with the compact support for any natural coefficient of
+scaling $N\ge 2$ is given. Examples of construction of wavelets for
+coefficients of scaling N=2 and N=3 are produced.",0705.4150v1
+2007-08-24,Experiments with a Positivity Preserving Operator,"We consider some multivariate rational functions which have (or are
+conjectured to have) only positive coefficients in their series expansion. We
+consider an operator that preserves positivity of series coefficients, and
+apply the inverse of this operator to the rational functions. We obtain new
+rational functions which seem to have only positive coefficients, whose
+positivity would imply positivity of the original series, and which, in a
+certain sense, cannot be improved any further.",0708.3286v1
+2007-10-31,A version of Fabry's theorem for power series with regularly varying coefficients,"For real power series whose non-zero coefficients satisfy $|a_m|^{1/m}\to~1$
+we prove a stronger version of Fabry theorem relating the frequency of sign
+changes in the coefficients and analytic continuation of the sum of the power
+series.",0710.5894v2
+2008-05-03,Alternatives to Pearson's and Spearman's Correlation Coefficients,"This article presents several alternatives to Pearson's correlation
+coefficient and many examples. In the samples where the rank in a discrete
+variable counts more than the variable values, the mixtures that we propose of
+Pearson's and Spearman's correlation coefficients give better results.",0805.0383v1
+2008-06-02,Hopf-cyclic homology with contramodule coefficients,"A new class of coefficients for the Hopf-cyclic homology of module algebras
+and coalgebras is introduced. These coefficients, termed stable
+anti-Yetter-Drinfeld contramodules, are both modules and contramodules of a
+Hopf algebra that satisfy certain compatibility conditions.",0806.0389v2
+2008-07-06,Second-order elliptic equations with variably partially VMO coefficients,"The solvability in $W^{2}_{p}(\bR^{d})$ spaces is proved for second-order
+elliptic equations with coefficients which are measurable in one direction and
+VMO in the orthogonal directions in each small ball with the direction
+depending on the ball. This generalizes to a very large extent the case of
+equations with continuous or VMO coefficients.",0807.0926v2
+2008-11-13,The p-adic valuation of k-central binomial coefficients,"The coefficients c(n,k) defined by (1-k^2x)^(-1/k) = sum c(n,k) x^n reduce to
+the central binomial coefficients for k=2. Motivated by a question of H.
+Montgomery and H. Shapiro for the case k=3, we prove that c(n,k) are integers
+and study their divisibility properties.",0811.2028v1
+2008-12-08,Commutativity and Ideals in Category Crossed Products,"In order to simultaneously generalize matrix rings and group graded crossed
+products, we introduce category crossed products. For such algebras we describe
+the center and the commutant of the coefficient ring. We also investigate the
+connection between on the one hand maximal commutativity of the coefficient
+ring and on the other hand nonemptyness of intersections of the coefficient
+ring by nonzero twosided ideals.",0812.1468v1
+2009-02-27,Estimation in nonstationary random coefficient autoregressive models,"We investigate the estimation of parameters in the random coefficient
+autoregressive model. We consider a nonstationary RCA process and show that the
+innovation variance parameter cannot be estimated by the quasi-maximum
+likelihood method. The asymptotic normality of the quasi-maximum likelihood
+estimator for the remaining model parameters is proven so the unit root problem
+does not exist in the random coefficient autoregressive model.",0903.0022v1
+2009-03-04,SPDEs in divergence form with VMO coefficients and filtering theory of partially observable diffusion processes with Lipschitz coefficients,"We present several results on the smoothness in $L_{p}$ sense of filtering
+densities under the Lipschitz continuity assumption on the coefficients of a
+partially observable diffusion processes. We obtain them by rewriting in
+divergence form filtering equation which are usually considered in terms of
+formally adjoint to operators in nondivergence form.",0903.0877v1
+2009-03-25,Coefficients of the poles of local zeta functions and their applications to oscillating integrals,"We introduce a new method which enables us to calculate the coefficients of
+the poles of local zeta functions very precisely and prove some explicit
+formulas. Some vanishing theorems for the candidate poles of local zeta
+functions will be also given. Moreover we apply our method to oscillating
+integrals and obtain an explicit formula for the coefficients of their
+asymptotic expansions.",0903.4265v1
+2009-04-06,Hall Coefficient of Dirac Fermions in Graphene under Charged Impurity Scatterings,"With a conserving formalism within the self-consistent Born approximation, we
+study the Hall conductivity of Dirac fermions in graphene under charged
+impurity scatterings. The calculated inverse Hall coefficient is compared with
+the experimental data. It is shown that the present calculations for the Hall
+coefficient and the electric conductivity are in good agreement with the
+experimental measurements.",0904.0959v1
+2009-05-26,The image of the coefficient space in the universal deformation space,"The coefficient space is a kind of resolution of singularities of the
+universal flat deformation space for a given Galois representation of some
+local field. It parameterizes (in some sense) the finite flat models for the
+Galois representation. The aim of this note is to determine the image of the
+coefficient space in the universal deformation space.",0905.4289v2
+2009-06-13,"Comments on ""Slip coefficient in nanoscale pore flow"" (arXiv:0805.1666)","We make some remarks on Sokhan and Quirke's [{\it Phys. Rev. E} 78, 015301(R)
+(2008)] paper (arXiv:0805.1666). Sokhan and Quirke mentioned that, considering
+their main result, {the slip coefficient is independent of the external force
+(flux)} which is not consistent with previous measurements and approaches. We
+also discuss the sudden changes of the slip coefficient for larger Knudsen
+numbers or smaller nanopores.",0906.2436v1
+2009-07-14,On divergence form SPDEs with growing coefficients in $W^{1}_{2}$ spaces without weights,"We consider divergence form uniformly parabolic SPDEs with bounded and
+measurable leading coefficients and possibly growing lower-order coefficients
+in the deterministic part of the equations. We look for solutions which are
+summable to the second power with respect to the usual Lebesgue measure along
+with their first derivatives with respect to the spatial variable.",0907.2467v2
+2009-09-29,On divergence form second-order PDEs with growing coefficients in $W^{1}_{p}$ spaces without weights,"We consider second-order divergence form uniformly parabolic and elliptic
+PDEs with bounded and $VMO_{x}$ leading coefficients and possibly linearly
+growing lower-order coefficients. We look for solutions which are summable to
+the $p$th power with respect to the usual Lebesgue measure along with their
+first derivatives with respect to the spatial variables.",0909.5248v1
+2009-10-15,$p$-adic properties of coefficients of weakly holomorphic modular forms,"We examine the Fourier coefficients of modular forms in a canonical basis for
+the spaces of weakly holomorphic modular forms of weights 4, 6, 8, 10, and 14,
+and show that these coefficients are often highly divisible by the primes 2, 3,
+and 5.",0910.2997v1
+2009-10-22,On some functionals associated with certain coefficient problems,"Under certain conditions, we obtain sharp bounds on some functionals defined
+in the coefficient space of starlike functions. It has been found that the
+functionals are closely associated with certain coefficient problems, which are
+of independent interest.",0910.4310v1
+2009-11-16,"Optimal Quadrature Formulas with Positive Coefficients in $L_2^{(m)}(0,1)$ Space","In the Sobolev space $L_2^{(m)}(0,1)$ optimal quadrature formulas with the
+nodes (1.5) are investigated. For optimal coefficients explicit form are
+obtained and norm of the error functional is calculated. In particular, by
+choosing parameter $\eta_0$ in (1.5) the optimal quadrature formulas with
+positive coefficients are obtained and compared with well known optimal
+formulas.",0911.2896v1
+2009-12-03,Supercongruences satisfied by coefficients of 2F1 hypergeometric series,"Recently, Chan, Cooper and Sica conjectured two congruences for coefficients
+of classical 2F1 hypergeometric series which also arise from power series
+expansions of modular forms in terms of modular functions. We prove these two
+congruences using combinatorial properties of the coefficients.",0912.0620v1
+2009-12-22,On the Basis Property of the Root Functions of Differential Operators with Matrix Coefficients,"We obtain asymptotic formulas for eigenvalues and eigenfunctions of the
+operator generated by a system of ordinary differential equations with summable
+coefficients and periodic or antiperiodic boundary conditions. Then using these
+asymptotic formulas, we find necessary and sufficient conditions on the
+coefficients for which the system of eigenfunctions and associated functions of
+the operator under consideration forms a Riesz basis.",0912.4340v1
+2010-04-20,On the successive coefficients of certain univalent functions,"The object of this paper is to study relationship between successive
+coefficients of some subclasses of the class of univalent functions in the unit
+disk. the result obtained is sharp, and is used to provide a new, short proof
+of the well-known conjecture of Robertson on the coefficients of
+close-to-convex functions.",1004.3383v1
+2010-07-15,Certain Binomial Sums with recursive coefficients,"In this short note, we establish some identities containing sums of binomials
+with coefficients satisfying third order linear recursive relations. As a
+result and in particular, we obtain general forms of earlier identities
+involving binomial coefficients and Fibonacci type sequences.",1007.2676v1
+2010-09-30,Polynomial differential equations with piecwise linear coefficients,"Cubic and quartic non-autonomous differential equations with continuous
+piecewise linear coefficients are considered. The main concern is to find the
+maximum possible multiplicity of periodic solutions. For many classes, we show
+that the mutiplicity is the same when the coefficients are polynomial functions
+of degree n or piecewise linear functions with n segments.",1009.6019v1
+2010-10-11,Clebsch--Gordan Coefficients of the Quaternion Group,"The Clebsch--Gordan coefficients of the Kronecker products of the irreducible
+representations of the Quaternion Group Q8, of the Generalized Quaternion
+Groups Q16 and Q32, and of the factor group (Q32 X Q32)/{(1,1),(-1,-1)} are
+computed as eigenvectors of a well-known matrix of triple-products of the
+irreducible representations.",1010.2249v1
+2010-10-17,Stochastic Homeomorphism Flows of SDEs with Singular Drifts and Sobolev Diffusion Coefficients,"In this paper we prove the stochastic homeomorphism flow property and the
+strong Feller property for stochastic differential equations with sigular time
+dependent drifts and Sobolev diffusion coefficients. Moreover, the local well
+posedness under local assumptions are also obtained. In particular, we extend
+Krylov and R\""ockner's results in \cite{Kr-Ro} to the case of non-constant
+diffusion coefficients.",1010.3403v2
+2011-01-14,Cohomology with coefficients in stacks of Picard categories,"Cohomology of a topological space with coefficients in stacks of abelian
+2-groups is considered. A 2-categorical analog of the theorem of Grothendieck
+is proved, relating cohomology of the space with coefficients in a 2-stage
+spectrum and the Ext groups of appropriate stacks.",1101.2918v2
+2011-04-04,A Note on The Positivity of the Coefficients of Some Power Series Expansions,"In this short note, a general result concerning the positivity, under some
+conditions, of the coefficients of a power series is proved. This allows us to
+answer positively a question raised by Guo (2010) about the sign of the
+coefficients of a power series relating the residual errors in Halley's
+iterations for the $p$th root.",1104.0470v1
+2011-05-02,Elliptic equations with singular BMO coefficients in Reifenberg domains,"$W^{1, p}$ estimate for the solutions of elliptic equations whose coefficient
+matrix can have large jump along the boundary of subdomains is obtained. The
+principal coefficients are supposed to be in the John-Nirenberg space with
+small BMO seminorms. The domain and subdomains are Reifenberg flat domains and
+moreover, it has been shown that the estimates are uniform with respect to the
+distance between the subdomains.",1105.0228v1
+2011-05-06,The subgroup growth spectrum of virtually free groups,"For a finitely generated group $\Gamma$ denote by $\mu(\Gamma)$ the growth
+coefficient of $\Gamma$, that is, the infimum over all real numbers $d$ such
+that $s_n(\Gamma)<n!^d$. We show that the growth coefficient of a virtually
+free group is always rational, and that every rational number occurs as growth
+coefficient of some virtually free group. Moreover, we describe an algorithm to
+compute $\mu$.",1105.1297v1
+2011-06-06,Divisibility Properties of Coefficients of Level $p$ Modular Functions for Genus Zero Primes,"Lehner's 1949 results on the $j$-invariant showed high divisibility of the
+function's coefficients by the primes $p\in\{2,3,5,7\}$. Expanding his results,
+we examine a canonical basis for the space of level $p$ modular functions
+holomorphic at the cusp 0. We show that the Fourier coefficients of these
+functions are often highly divisible by these same primes.",1106.1188v1
+2011-07-19,Removal of UV cutoff for the Nelson model with variable coefficients,"We consider the Nelson model with variable coefficients. Nelson models with
+variable coefficients arise when one replaces in the usual Nelson model the
+flat Minkowski metric by a static metric, allowing also the boson mass to
+depend on position. We study the removal of the ultraviolet cutoff.",1107.3815v1
+2011-12-14,Mixed Boundary Value Problems of Semilinear Elliptic PDEs and BSDEs with Singular Coefficients,"In this paper, we prove that there exists a unique weak solution to the mixed
+boundary value problem for a general class of semilinear second order elliptic
+partial differential equations with singular coefficients. Our approach is
+probabilistic. The theory of Dirichlet forms and backward stochastic
+differential equations with singular coefficients and infinite horizon plays a
+crucial role.",1112.3148v1
+2011-12-21,A Loewner variational method in the theory of schlicht functions,"A Loewner variational method is developed that allows to calculate arbitrary
+continuous coefficient functionals of the second, third and fourth coefficients
+of schlicht functions. Based on this method an improved lower bound for the
+Milin-constant(0.034856..) is given, as well as an improved lower bound for the
+maximal modulus of the seventh coefficient of odd schlicht
+functions(1.006763..).",1112.5187v2
+2012-02-06,A probabilistic interpretation of a sequence related to Narayana polynomials,"A sequence of coefficients appearing in a recurrence for the Narayana
+polynomials is generalized. The coefficients are given a probabilistic
+interpretation in terms of beta distributed random variables. The recurrence
+established by M. Lasalle is then obtained from a classical convolution
+identity. Some arithmetical properties of the generalized coefficients are also
+established.",1202.1203v3
+2012-03-08,Generating multivariate extreme value distributions,"We define in a probabilistic way a parametric family of multivariate extreme
+value distributions. We derive its copula, which is a mixture of several
+complete dependent copulas and total independent copulas, and the bivariate
+tail dependence and extremal coefficients. Based on the obtained results for
+these coefficients, we propose a method to built multivariate extreme value
+distributions with prescribed tail/extremal coefficients. We illustrate the
+results with examples of simulation of these distributions.",1203.1875v1
+2012-03-18,A Remark on Coefficients of Jacobi Matrices Arising from a Schrodinger Operator,"A discrete analogue of a Schrodinger type operator proposed by J. Bellissard
+has a singular continuous spectrum. In this remark we answer the conjecture
+formulated by D. Bessis, M. Mehta and P. Moussa on the coefficients of that
+operator. It turns out that the coefficients have a more complicated behavior
+than it was conjectured.",1203.4005v1
+2012-03-26,Variation of Hilbert Coefficients,"For a Noetherian local ring $(\RR, \m)$, the first two Hilbert coefficients,
+$e_0$ and $e_1$, of the $I$-adic filtration of an $\m$-primary ideal $I$ are
+known to code for properties of $\RR$, of the blowup of $\spec(\RR)$ along
+$V(I)$, and even of their normalizations. We give estimations for these
+coefficients when $I$ is enlarged (in the case of $e_1$ in the same integral
+closure class) for general Noetherian local rings.",1203.5578v1
+2012-05-20,On reconstruction of Lamé coefficients from partial Cauchy data in three dimensions,"For the isotropic Lam\'e system, we prove in dimensions three or larger that
+both Lam\'e coefficients are uniquely recovered from partial Cauchy data on an
+arbitrary open subset of the boundary provided that the coefficient $\mu$ is a
+priori close to a constant.",1205.4436v1
+2012-06-19,A real analytic family of fundamental solutions of elliptic partial differential operators with real constant coefficients,"We construct of a family of fundamental solutions for elliptic partial
+differential operators with real constant coefficients. The elements of such a
+family are expressed by means of jointly real analytic functions of the
+coefficients of the operators and of the spatial variable. We show regularity
+properties in the frame of Schauder spaces for the corresponding single layer
+potentials.",1206.4211v1
+2012-09-03,Absence of Renormalization of the Specific Heat Coefficient of the Interacting Fermion Systems,"Contrary to the longtime and widely conceived belief, we proved that the
+specific heat coefficient $\gamma$ --also called Sommerfeld coefficient -- of
+the interacting Fermion system is not renormalized by the wave-function
+renormalization factor $Z$ as far as the system remains a Fermi liquid state.",1209.0328v2
+2012-11-30,On the Coefficients of a Hyperbolic Hydrodynamic Model,"Based on the Nakajima-Zubarev type nonequilibrium density operator, we derive
+a hyperbolic hydrodynamical equation. Microscopic Kubo-formulas for all
+coefficients in the hyperbolic hydrodynamics are obtained. Coefficients
+$\alpha_{i}$'s and $\beta_{i}$'s in the Israel-Stewart equation are given as
+current-weighted correlation lengths which are to be calculated in statistical
+mechanics.",1211.7173v1
+2013-01-30,Jumps of ternary cyclotomic coefficients,"It is known that two consecutive coefficients of a ternary cyclotomic
+polynomial $\Phi_{pqr}(x)=\sum_k a_{pqr}(k)x^k$ differ by at most one. In this
+paper we give a criterion on $k$ to satisfy $|a_{pqr}(k)-a_{pqr}(k-1)|=1$. We
+use this to prove that the number of nonzero coefficients of the $n$th ternary
+cyclotomic polynomial is greater than $n^{1/3}$.",1301.7174v1
+2013-03-27,From Fourier to Gegenbauer: Dimension walks on spheres,"We show that the even- resp. odd-dimensional Schoenberg coefficients in
+Gegenbauer expansions of isotropic positive definite functions on the d-sphere
+can be expressed as linear combinations of Fourier resp. Legendre coefficients,
+and we give closed form expressions for the coefficients involved in these
+expansions.",1303.6856v2
+2013-04-18,Unimodality via Kronecker products,"We present new proofs and generalizations of unimodality of the q-binomial
+coefficients \binom{n}{k}_q as polynomials in q. We use an algebraic approach
+by interpreting the differences between numbers of certain partitions as
+Kronecker coefficients of representations of S_n. Other applications of this
+approach include strict unimodality of the diagonal q-binomial coefficients and
+unimodality of certain partition statistics.",1304.5044v2
+2013-05-14,On the relationships between Fourier - Stieltjes coefficients and spectra of measures,"We construct examples of uncountable compact subsets of complex numbers with
+the property that any Borel measure on the circle group taking values of its
+Fourier coefficients from this set has natural spectrum. For measures with
+Fourier coefficients tending to 0 we construct tho open set with this property.",1305.3324v2
+2013-06-21,Strict unimodality of q-binomial coefficients,"We prove strict unimodality of the q-binomial coefficients \binom{n}{k}_q as
+polynomials in q. The proof is based on the combinatorics of certain Young
+tableaux and the semigroup property of Kronecker coefficients of S_n
+representations.",1306.5085v2
+2013-07-30,On Poisson operators and Dirichlet-Neumann maps in H^s for divergence form elliptic operators with Lipschitz coefficients,"We consider second order uniformly elliptic operators of divergence form in
+$\R^{d+1}$ whose coefficients are independent of one variable. Under the
+Lipschitz condition on the coefficients we characterize the domain of the
+Poisson operators and the Dirichlet-Neumann maps in the Sobolev space
+$H^s(\R^d)$ for each $s\in [0,1]$. Moreover, we also show a factorization
+formula for the elliptic operator in terms of the Poisson operator.",1307.8151v1
+2013-08-13,Multivalued backward doubly stochastic differential equations with time delayed coefficients,"In this paper, we deal with a class of multivalued backward doubly stochastic
+differential equations with time delayed coefficients. Based on a slight
+extension of the existence and uniqueness of solutions for backward doubly
+stochastic differential equations with time delayed coefficients, we establish
+the existence and uniqueness of solutions for these equations by means of
+Yosida approximation.",1308.2748v2
+2013-09-26,Fourier Coefficients Of Some Cusp Forms,"The possible values of the nth Fourier coefficients a(n) of some cusp forms
+f(z) of weight k => 12 are studied in this article. In particular, the values
+of the tau function are investigated in some details, and proved that tau(p) =!
+0 for all primes p => p_0.",1309.6965v2
+2013-11-10,Constant Coefficients in the Radial Komatu-Loewner Equation for Multiple Slits,"The radial Komatu-Loewner equation is a differential equation for certain
+normalized conformal mappings that can be used to describe the growth of slits
+within multiply connected domains. We show that it is possible to choose
+constant coefficients in this equation in order to generate given disjoint
+slits and that those coefficients are uniquely determined under a suitable
+normalization of the differential equation.",1311.2279v1
+2013-12-11,On correct solvability of a Dirichlet problem for generalized Manjeron equation with non-smooth coefficients,"In the paper obtained equivalent system of Fredholm integral equations in the
+study of the Dirichlet problem for the generalized Manjeron equation with
+non-smooth coefficients in non-classical treatment (1), (4). When non-smooth
+conditions on the coefficients of the equation in a rectangular region for this
+problem posed are found correct solvability conditions in integral form based
+on the method of integral representations.",1312.3318v1
+2014-02-16,The coefficients of the period polynomials,"A general description of the Vi\`ete coefficients of the gaussian period
+polynomials is given, in terms of certain symmetric representations of the
+subgroups and the corresponding quotient groups of the multiplicative group
+\mathbf{F}_{p}^{*} of a finite prime field of characteristics p, an odd prime
+number. The known values of these coefficients are recovered by this technique
+and further results of general nature are presented.",1402.3833v1
+2014-03-19,Divisors of Fourier coefficients of modular forms,"Let $d(n)$ denote the number of divisors of $n$. In this paper, we study the
+average value of $d(a(p))$, where $p$ is a prime and $a(p)$ is the $p$-th
+Fourier coefficient of a normalized Hecke eigenform of weight $k \ge 2$ for
+$\Gamma_0(N)$ having rational integer Fourier coefficients.",1403.4709v1
+2014-03-24,On an explicit representation of central $(2k+1)$-nomial coefficients,"We propose an explicit representation of central $(2k+1)$-nomial coefficients
+in terms of finite sums over trigonometric constructs. The approach utilizes
+the diagonalization of circulant boolean matrices and is generalizable to all
+$(2k+1)$-nomial coefficients, thus yielding a new family of combinatorical
+identities.",1403.5942v1
+2014-08-04,Approximation of elliptic equations with BMO coefficients,"We study solution techniques for elliptic equations in divergence form, where
+the coefficients are only of bounded mean oscillation (BMO). For
+$|p-2|<\varepsilon$ and a right hand side in $W^{-1}_p$ we show convergence of
+a finite element scheme, where $\varepsilon$ depends on the oscillation of the
+coefficients.",1408.0724v1
+2014-08-22,Measures for orthogonal polynomials with unbounded recurrence coefficients,"Systems of orthogonal polynomials whose recurrence coefficients tend to
+infinity are considered. A summability condition is imposed on the coefficients
+and the consequences for the measure of orthogonality are discussed. Also
+discussed are asymptotics for the polynomials.",1408.5349v3
+2014-10-14,Low-rank approximation of elliptic boundary value problems with high-contrast coefficients,"We analyze the convergence of degenerate approximations to Green's function
+of elliptic boundary value problems with high-contrast coefficients. It is
+shown that the convergence is independent of the contrast if the error is
+measured with respect to suitable norms. This lays ground to fast methods
+(so-called hierarchical matrix approximations) which do not have to be adapted
+to the coefficients.",1410.3717v1
+2014-11-03,On the coefficients of TYZ expansion of locally Hermitian symmetric spaces,"In this paper we address the problem of studying those K\""ahler manifolds
+whose first two coefficients of the associated TYZ expansion vanish and we
+prove that for a locally Hermitian symmetric space this happens only in the
+flat case. We also prove that there exist nonflat locally Hermitian symmetric
+spaces where all the odd coefficients vanish.",1411.0455v1
+2014-11-19,Dissipative Heat Decomposition in Stochastic Energetics: Implication of the Instantaneous Diffusion Coefficient in Nonequilibrium Steady States,"We give a decomposition expression for dissipative heat using the
+instantaneous diffusion coefficient in a nonequilibrium steady state. The
+dissipative heat can be expressed using three diffusion coefficients:
+instantaneous, equilibrium, and drift. An experimental application of the
+decomposition expression permits us to evaluate the heat dissipation rate from
+single-trajectory data only. We also numerically demonstrate this method.",1411.5155v1
+2014-12-18,Iterated bar complexes and E_n-homology with coefficients,"The first author proved in a previous paper that the n-fold bar construction
+for commutative algebras can be generalized to E_n-algebras, and that one can
+calculate E_n-homology with trivial coefficients via this iterated bar
+construction. We extend this result to E_n-homology and E_n-cohomology of a
+commutative algebra A with coefficients in a symmetric A-bimodule.",1412.6032v2
+2014-12-22,Sign changes of coefficients of certain Dirichlet series,"In this paper, we give criteria for infinitely many sign changes of the
+coefficients of any Dirichlet series if the coefficients are real numbers. We
+also provide examples where our criteria are applicable.",1412.7044v1
+2015-01-08,On the coefficients of power sums of arithmetic progressions,"We investigate the coefficients of the polynomial \[
+S_{m,r}^n(\ell)=r^n+(m+r)^n+(2m+r)^n+\cdots+((\ell-1)m+r)^n. \] We prove that
+these can be given in terms of Stirling numbers of the first kind and
+$r$-Whitney numbers of the second kind. Moreover, we prove a necessary and
+sufficient condition for the integrity of these coefficients.",1501.01843v1
+2015-05-05,Coefficient Extraction Formula and Furstenberg's Theorems,"In this article, using a Proposition of Furstenberg, we give a coefficient
+extraction formula for algebraic series that is valid for all fields, of which
+the Flajolet-Soria coefficient extraction formula for the complex field is a
+special case.",1505.01379v3
+2015-06-30,Generating functions for the osp(1|2) Clebsch-Gordan coefficients,"Generating functions for Clebsch-Gordan coefficients of osp(1|2) are derived.
+These coefficients are expressed as q goes to - 1 limits of the dual q-Hahn
+polynomials. The generating functions are obtained using two different
+approaches respectively based on the coherent-state representation and the
+position representation of osp(1j2).",1507.00018v1
+2015-08-20,Square function estimates on layer potentials for higher-order elliptic equations,"In this paper we establish square-function estimates on the double and single
+layer potentials for divergence-form elliptic operators, of arbitrary even
+order 2m, with variable t-independent coefficients in the upper half-space.
+This generalizes known results for variable-coefficient second-order operators,
+and also for constant-coefficient higher-order operators.",1508.04988v1
+2015-08-26,Multidimensional BSDEs with uniformly continuous coefficients: the general result,"In this paper, by introducing a new notion of envelope of the stochastic
+process, we construct a family of random differential equations whose solutions
+can be viewed as solutions of a family of ordinary differential equations and
+prove that the multidimensional backward stochastic differential equations
+(BSDEs for short) with the general uniformly continuous coefficients are
+uniquely solvable. As a result, we solve the open problem of multidimensional
+BSDEs with uniformly continuous coefficients.",1508.06671v1
+2015-11-23,Exponential decay rate of partial autocorrelation coefficients of ARMA and short-memory processes,"We present a short proof of the fact that the exponential decay rate of
+partial autocorrelation coefficients of a short-memory process, in particular
+an ARMA process, is equal to the exponential decay rate of the coefficients of
+its infinite autoregressive representation.",1511.07091v2
+2015-11-30,Convoluted Fourier Coefficients of GL(n)-Automorphic Functions. Part 1,"We study certain cases of convoluted Fourier coefficients of
+$GL_n$-automorphic functions. We establish identities that express them in
+terms of Fourier coefficients related to unipotent orbits. The most general
+case that is studied is $(n)\circ(k,2^{n-1})$. The conclusions for this case is
+only up to a conjecture that I state. However there are certain special cases
+and other examples that are not based on any conjecture.",1511.09374v1
+2016-01-11,On Milstein approximations with varying coefficients: the case of super-linear diffusion coefficients,"A new class of explicit Milstein schemes, which approximate stochastic
+differential equations (SDEs) with superlinearly growing drift and diffusion
+coefficients, is proposed in this article. It is shown, under very mild
+conditions, that these explicit schemes converge in $\mathcal L^p$ to the
+solution of the corresponding SDEs with optimal rate.",1601.02695v1
+2016-01-28,Gradient estimates for solutions of the Lamé system with partially infinite coefficients in dimensions greater than two,"We establish upper bounds on the blow-up rate of the gradients of solutions
+of the Lam\'{e} system with partially infinite coefficients in dimensions
+greater than two as the distance between the surfaces of discontinuity of the
+coefficients of the system tends to zero.",1601.07879v1
+2016-02-08,On p-adic approximation of sums of binomial coefficients,"We propose higher-order generalizations of Jacobsthal's $p$-adic
+approximation for binomial coefficients. Our results imply explicit formulae
+for linear combinations of binomial coefficients $\binom{ip}{p}$
+($i=1,2,\dots$) that are divisible by arbitrarily large powers of prime $p$.",1602.02632v2
+2016-02-29,On Fourier coefficients of modular forms of half integral weight at squarefree integers,"We show that the Dirichlet series associated to the Fourier coefficients of a
+half-integral weight Hecke eigenform at squarefree integers extends
+analytically to a holomorphic function in the half-plane $\re
+s\textgreater{}\tfrac{1}{2}$. This exhibits a high fluctuation of the
+coefficients at squarefree integers.",1602.08924v2
+2016-04-04,Weak Error for the Euler Scheme Approximation of Diffusions with Non-Smooth Coefficients *,"We study the weak error associated with the Euler scheme of non degenerate
+diffusion processes with non smooth bounded coefficients. Namely, we consider
+the cases of H{\""o}lder continuous coefficients as well as piecewise smooth
+drifts with smooth diffusion matrices.",1604.00771v3
+2016-04-13,Hölder regularity for Maxwell's equations under minimal assumptions on the coefficients,"We prove global H\""older regularity for the solutions to the time-harmonic
+anisotropic Maxwell's equations, under the assumptions of H\""older continuous
+coefficients. The regularity hypotheses on the coefficients are minimal. The
+same estimates hold also in the case of bianisotropic material parameters.",1604.03741v2
+2016-05-24,Exponential decay of scattering coefficients,"We study an aspect of the following general question: which properties of a
+signal can be characterized by its scattering transform? We show that the
+energy contained in high order scattering coefficients is upper bounded by the
+energy contained in the high frequencies of the signal. This result links the
+decay of the scattering coefficients of a signal with the decay of its Fourier
+transform. Additionally, it allows to generalize some results of Mallat (2012),
+by relaxing the admissibility condition on the wavelet family.",1605.07464v1
+2016-06-20,Infinite Product Exponents for Modular Forms,"Recently, D. Choi obtained a description of the coefficients of the infinite
+product expansions of meromorphic modular forms over $\Gamma_0(N)$. Using this
+result, we provide some bounds on these infinite product coefficients for
+holomorphic modular forms. We give an exponential upper bound for the growth of
+these coefficients. We show that this bound is also a lower bound in the case
+that the genus of the associated modular curve $X_0(N)$ is $0$ or $1$.",1606.06122v1
+2016-07-02,Convergence rates of finite difference schemes for the linear advection and wave equation with rough coefficient,"We prove convergence rates of explicit finite difference schemes for the
+linear advection and wave equation in one space dimension with H\""older
+continuous coefficient. The obtained convergence rates explicitly depend on the
+H\""older regularity of the coefficient and the modulus of continuity of the
+initial data. We compare the theoretically established rates with the
+experimental rates of a couple of numerical examples.",1607.00525v1
+2016-07-18,Spacetime Variation of Lorentz-Violation Coefficients at Nonrelativistic Scale,"When the Standard-Model Extension (SME) is applied in curved spacetime, the
+Lorentz-violation coefficients must depend on spacetime position. This work
+describes some of the consequences of this spacetime variation. We focus on
+effects that appear at a nonrelativistic scale and extract sensitivity of
+completed experiments to derivatives of SME coefficient fields.",1607.05211v1
+2016-08-05,Exact Russell-Type Modular Equations,"This paper provides some statistics for the coefficients of Russell- Type
+modular equations for the modular function, {\lambda}({\tau}). The results hold
+uniformly for all odd primes. They do not rely on any numerical evaluations of
+coefficients of q expansions of {\lambda}. The method relies on an internal
+structure of the coefficients of {\lambda} expressed in terms of multiplicative
+functions defined on integer partitions. The method may be extended to other
+types of modular equations.",1608.01765v1
+2017-02-15,On homology with coefficients and generalized inductions,"In group representations several inductions given by tensoring with
+appropriate bimodules may be reconstructed via homology of $G$-posets with
+$G$-equivariant coefficients. For this purpose, we need various local
+categories of a finite group $G$, which afford the coefficients. Consequently,
+the functors among local categories give rise to the homology constructions
+naturally, and may be used to reformulate some existing results, as well as to
+deduce new statements.",1702.04496v2
+2017-03-24,Additive bases with coefficients of newforms,"Let $f(z)=\sum_{n=1}^{\infty}a(n) e^{2\pi i nz}$ be a normalized Hecke
+eigenform in $S_{2k}^{\text{new}}(\Gamma_0(N))$ with integer Fourier
+coefficients. We prove that there exists a constant $C(f)>0$ such that any
+integer is a sum of at most $C(f)$ coefficients $a(n) $. It holds
+$C(f)\ll_{\varepsilon,k}N^{\frac{6k-3}{16}+\varepsilon}$.",1703.08473v1
+2017-04-01,Symmetry and Piezoelectricity: Evaluation of $α$-Quartz coefficients,"Piezoelectric coefficients of $\alpha$-Quartz are derived from symmetry
+arguments based on Neumann's Principle with three different methods: Fumi,
+Landau-Lifshitz and Royer-Dieulesaint. While Fumi method is tedious and
+Landau-Lifshitz requires additional physical principles to evaluate the
+piezoelectric coefficients, Royer-Dieulesaint is the most elegant and most
+efficient of the three techniques.",1704.01012v1
+2017-04-05,Quantitative unique continuation of solutions to higher order elliptic equations with singular coefficients,"We investigate the quantitative unique continuation of solutions to higher
+order elliptic equations with singular coefficients. Quantitative unique
+continuation described by the vanishing order is a quantitative form of strong
+unique continuation property. We characterize the vanishing order of solutions
+for higher order elliptic equations in terms of the norms of coefficient
+functions in their respective Lebesgue spaces. New versions of quantitative
+Carleman estimates are established.",1704.01446v2
+2017-05-27,Explicit formulas and vanishing conditions for certain coefficients of Drinfeld-Goss Hecke eigenforms,"We obtain a closed form polynomial expression for certain coefficients of
+Drinfeld-Goss double-cuspidal modular forms which are eigenforms for the degree
+one Hecke operators with power eigenvalues, and we use those formulas to prove
+vanishing results for an infinite family of those coefficients.",1705.09795v1
+2017-06-08,Consistency Results for Stationary Autoregressive Processes with Constrained Coefficients,"We consider stationary autoregressive processes with coefficients restricted
+to an ellipsoid, which includes autoregressive processes with absolutely
+summable coefficients. We provide consistency results under different norms for
+the estimation of such processes using constrained and penalized estimators. As
+an application we show some weak form of universal consistency. Simulations
+show that directly including the constraint in the estimation can lead to more
+robust results.",1706.02492v1
+2017-07-21,Binomial collisions and near collisions,"We describe efficient algorithms to search for cases in which binomial
+coefficients are equal or almost equal, give a conjecturally complete list of
+all cases where two binomial coefficients differ by 1, and give some identities
+for binomial coefficients that seem to be new.",1707.06893v2
+2017-10-12,Kinetic theory for strong uniform shear flow of granular media at high density,"We discuss the uniform shear flow of a fluidized granular bed composed of
+monodisperse Hertzian spheres. Considering high densities around the glass
+transition density of inelastic Hertzian spheres, we report kinetic theory
+expressions for the Newtonian viscosity as well as the Bagnold coefficient. We
+discuss the dependence of the transport coefficients on density and coefficient
+of restitution.",1710.04480v1
+2017-10-17,Oscillatory behavior and equidistribution of signs of Fourier coefficients of cusp forms,"In this paper, we discuss questions related to the oscillatory behavior and
+the equidistribution of signs for certain subfamilies of Fourier coefficients
+of integral weight newforms with a non-trivial nebentypus as well as Fourier
+coefficients of eigenforms of half-integral weight reachable by the Shimura
+correspondence.",1710.06211v3
+2017-12-26,Weak hamiltonian Wilson Coefficients from Lattice QCD,"In this work we present a calculation of the Wilson Coefficients $C_1$ and
+$C_2$ of the Effective Weak Hamiltonian to all-orders in $\alpha_s$, using
+lattice simulations. Given the current availability of lattice spacings we
+restrict our calculation to unphysically light $W$ bosons around 2 GeV and we
+study the systematic uncertainties of the two Wilson Coefficients.",1712.09241v1
+2018-04-09,Definite Sums as Solutions of Linear Recurrences With Polynomial Coefficients,"We present an algorithm which, given a linear recurrence operator $L$ with
+polynomial coefficients, $m \in \mathbb{N}\setminus\{0\}$, $a_1,a_2,\ldots,a_m
+\in \mathbb{N}\setminus\{0\}$ and $b_1,b_2,\ldots,b_m \in \mathbb{K}$, returns
+a linear recurrence operator $L'$ with rational coefficients such that for
+every sequence $h$, \[ L\left(\sum_{k=0}^\infty \prod_{i=1}^m \binom{a_i n +
+b_i}{k} h_k\right) = 0 \] if and only if $L' h = 0$.",1804.02964v1
+2018-04-12,On the largest Kronecker and Littlewood--Richardson coefficients,"We give new bounds and asymptotic estimates for Kronecker and
+Littlewood--Richardson coefficients. Notably, we resolve Stanley's questions on
+the shape of partitions attaining the largest Kronecker and
+Littlewood--Richardson coefficients. We apply the results to asymptotics of the
+number of standard Young tableaux of skew shapes.",1804.04693v2
+2018-05-01,Simultaneous behaviour of the Fourier coefficients of two Hilbert modular cusp forms,"In this article, we study the simultaneous sign changes of the Fourier
+coefficients of two Hilbert cusp forms of different integral weights. We also
+study the simultaneous non-vanishing of Fourier coefficients, of two distinct
+non-zero primitive Hilbert cuspidal non-CM eigenforms of integral weights, at
+powers of a fixed prime ideal.",1805.00230v1
+2018-05-04,Distribution Dependent SDEs with Singular Coefficients,"Under integrability conditions on distribution dependent coefficients,
+existence and uniqueness are proved for McKean-Vlasov type SDEs with
+non-degenerate noise. When the coefficients are Dini continuous in the space
+variable, gradient estimates and Harnack type inequalities are derived. These
+generalize the corresponding results derived for classical SDEs, and are new in
+the distribution dependent setting.",1805.01682v1
+2018-05-08,Integrability of the Basener-Ross model with time-dependent coefficients,"The Basener-Ross system is a known model in Population Dynamics for the
+interaction of consumers and resources in an isolated habitat. For an extended
+version with time-dependent coefficients as a model of possible variations of
+the environtmental conditions, some relations among the coefficients are
+provided leading to the integrability of the system.",1805.02910v1
+2018-05-10,On logarithmic coefficients of certain starlike functions related to the vertical strip,"In the present paper two certain subclasses of the starlike functions
+associated with the vertical strip are considered. The main aim of this paper
+is to investigate some basic properties of these classes such as, subordination
+relations, sharp inequalities for sums involving logarithmic coefficients and
+estimate of logarithmic coefficients.",1805.03997v3
+2018-05-21,Strichartz estimates for Schrödinger operators with square potential with time-dependent coefficients,"Strichartz estimates for a time-decaying harmonic oscillator were proven with
+some assumptions of coefficients for the time-decaying harmonic potentials. The
+main results of this paper are to remove these assumptions and to enable us to
+deal with the more general coefficient functions. Moreover, we also prove
+similar estimates for time-decaying homogeneous magnetic fields.",1805.07991v3
+2018-06-07,$L_p$-estimates for time fractional parabolic equations with coefficients measurable in time,"We establish the $L_p$-solvability for time fractional parabolic equations
+when coefficients are merely measurable in the time variable. In the spatial
+variables, the leading coefficients locally have small mean oscillations. Our
+results extend a recent result in [6] to a large extent.",1806.02635v2
+2018-06-11,Big polynomial rings with imperfect coefficient fields,"We previously showed that the inverse limit of standard-graded polynomial
+rings with perfect coefficient field is a polynomial ring, in an uncountable
+number of variables. In this paper, we show that the same result holds with
+arbitrary coefficient field. We also prove an analogous result for
+ultraproducts of polynomial rings.",1806.04208v2
+2018-06-15,A bound of the $β$-mixing coefficient for point processes in terms of their intensity functions,"We prove a general inequality on $\beta$-mixing coefficients of point
+processes depending uniquely on their $n$-th order intensity functions. We
+apply this inequality in the case of determinantal point processes and show
+that the rate of decay of the $\beta$-mixing coefficients of a wide class of
+DPPs is optimal.",1806.05910v2
+2018-08-21,Functional convergence for moving averages with heavy tails and random coefficients,"We study functional convergence of sums of moving averages with random
+coefficients and heavy-tailed innovations. Under some standard moment
+conditions and the assumption that all partial sums of the series of
+coefficients are a.s. bounded between zero and the sum of the series we obtain
+functional convergence of the corresponding partial sum stochastic process in
+the space $D[0,1]$ of c\`{a}dl\`{a}g functions with the Skorohod $M_{2}$
+topology.",1808.07023v1
+2018-09-05,Parabolic Systems with measurable coefficients in weighted Sobolev spaces,"In this paper we present a weighted $L_p$-theory of parabolic systems on a
+half space. The leading coefficients are assumed to be only measurable in $t$
+and have small bounded mean oscillations (BMO) with respect to $x$, and the
+lower order coefficients are allowed to blow up near the boundary.",1809.01325v2
+2018-12-10,On the Interrelation between Dependence Coefficients of Extreme Value Copulas,"For extreme value copulas with a known upper tail dependence coefficient we
+find pointwise upper and lower bounds, which are used to establish upper and
+lower bounds of the Spearman and Kendall correlation coefficients. We shown
+that in all cases the lower bounds are attained on Marshall--Olkin copulas, and
+the upper ones, on copulas with piecewise linear dependence functions.",1812.03766v1
+2019-01-22,Moser's estimates for degenerate Kolmogorov equations with non-negative divergence lower order coefficients,"We prove the local boundedness of the solutions to degenerate second order
+partial differential equations of Kolmogorov type with measurable coefficients
+in divergence form, under minimal integrability assumption on the lower order
+coefficients.",1901.07345v2
+2019-02-24,Path-Distribution Dependent SDEs with Singular Coefficients,"In this paper, existence and uniqueness are proved for path-dependent
+McKean-Vlasov type SDEs with integrability conditions. Gradient estimates and
+Harnack type inequalities are derived in the case that the coefficients are
+Dini continuous in the space variable. These generalize the corresponding
+results derived for classical functional SDEs with singular coefficients.",1902.08953v1
+2019-03-19,An asymptotic Formula for the iterated exponential Bell Numbers,"In 1938 E. T. Bell introduced ""The Iterated Exponential Integers"". He proved
+that these numbers may be expressed by polynomials with rational coefficients.
+However, Bell gave no formulas for any of the coefficients except the trivial
+one, which is always 1. Our task has been to find the coefficient of the
+leading term, giving asymptotic information about these numbers.",1903.07979v1
+2019-04-14,Wolff Type Potential Estimates for Stationary Stokes Systems with Dini-BMO Coefficients,"The pointwise gradient estimate for weak solution pairs to the stationary
+Stokes system with Dini-BMO coefficients is established via the
+Havin-Maz'ya-Wolff type nonlinear potential of the nonhomogeneous term. In
+addition, we present a pointwise bound for the weak solutions under no extra
+regularity assumption on the coefficients.",1904.06684v1
+2019-04-16,On a Subclass of p-Valent Functions with Negative Coefficients Defined by Using Rafid Operator,"By using Rafid operator we define the subclass $R_{\mu,p}^\delta(\alpha;A,B)$
+and $P_{\mu,p}^\delta(\alpha; A,B)$ of analytic and p-valent functions with
+negative coefficients we investigate some sharp results including coefficients
+estimates, distortion theorem, radii of starlikeness, convexity,
+close-to-convexity, and modified-Hadamard product. Finally, we give an
+application of fractional calculus and Bernadi-Libora-Livingstion operator.",1904.07913v1
+2019-05-14,Non-existence of generalized splitting methods with positive coefficients of order higher than four,"We prove that generalized exponential splitting methods making explicit use
+of commutators of the vector fields are limited to order four when only real
+coefficients are admitted. This generalizes the restriction to order two for
+classical splitting methods with only positive coefficients.",1905.05492v1
+2019-12-14,Scattering for critical wave equations with variable coefficients,"We prove that solutions to the quintic semilinear wave equation with variable
+coefficients in $\mathbb R^{1+3}$ scatter to a solution to the corresponding
+linear wave equation. The coefficients are small and decay as $|x|\to\infty$,
+but are allowed to be time dependent. The proof uses local energy decay
+estimates to establish the decay of the $L^6$ norm of the solution as
+$t\to\infty$.",1912.06795v1
+2019-12-31,Fractional Dehn twists and modular invariants,"In this note, we establish a relationship between fractional Dehn twist
+coefficients of Riemann surface automorphisms and modular invariants of
+holomorphic families of algebraic curves. Specially, we give a characterization
+of pseudo-periodic maps with nontrivial fractional Dehn twist coefficients. We
+also obtain some uniform lower bounds of non-zero fractional Dehn twist
+coefficients.",1912.13236v2
+2020-01-08,Logarithmic Stability for Coefficients Inverse Problem of Coupled Wave Equations,"This paper investigates the identification of two coefficients in a coupled
+hyperbolic system with an observation on one component of the solution. Based
+on the the Carleman estimate for coupled wave equations a logarithmic type
+stability result is obtained by measurement data only in a suitably chosen
+subdomain under the assumption that the coefficients are given in a
+neighborhood of some subboundary.",2001.02379v2
+2020-01-13,Carleman estimate for complex second order elliptic operators with discontinuous Lipschitz coefficients,"In this paper, we derive a local Carleman estimate for the complex second
+order elliptic operator with Lipschitz coefficients having jump
+discontinuities. Combing the result in [BL] and the arguments in [DcFLVW], we
+present an elementary method to derive the Carleman estimate under the optimal
+regularity assumption on the coefficients.",2001.04071v1
+2020-02-29,Identification of Random Coefficient Latent Utility Models,"This paper provides nonparametric identification results for random
+coefficient distributions in perturbed utility models. We cover discrete and
+continuous choice models. We establish identification using variation in mean
+quantities, and the results apply when an analyst observes aggregate demands
+but not whether goods are chosen together. We require exclusion restrictions
+and independence between random slope coefficients and random intercepts. We do
+not require regressors to have large supports or parametric assumptions.",2003.00276v1
+2020-03-09,SDEs with random and irregular coefficients,"We consider It\^o uniformly nondegenerate equations with random coefficients.
+When the coefficients satisfy some low regularity assumptions with respect to
+the spatial variables and Malliavin differentiability assumptions on the sample
+points, the unique solvability of singular SDEs is proved by solving backward
+stochastic Kolmogorov equations and utilizing a modified Zvonkin type
+transformation.",2003.04436v2
+2020-03-12,Bohr phenomenon for operator valued functions with fixed initial coefficient,"The purpose of this article is to study Bohr inequalities involving the
+absolute values of the coefficients of an operator valued function. To be more
+specific, we establish an operator valued analogue of a classical result
+regarding the Bohr phenomenon for scalar valued functions with fixed initial
+coefficient. Apart from that, operator valued versions of other related and
+well known results are obtained.",2003.05810v1
+2020-03-15,Symplectic Eisenstein Series,"We compute explicit formulae for the constant terms and Fourier coefficients
+for Eisenstein series on $\operatorname{Sp}(4,\mathbb{R})$, in terms of zeta
+functions and Whittaker functions. We also develop a generalisation of
+Ramanujan sums to $\operatorname{Sp}(4,\mathbb{Z})$, which appears as
+coefficients in the Fourier coefficients for the minimal Eisenstein series.",2003.06890v1
+2020-05-04,On the $RO(G)$-graded coefficients of dihedral equivariant cohomology,"We completely calculate the $RO(G)$-graded coefficients of ordinary
+equivariant cohomology where $G$ is the dihedral group of order $2p$ for a
+prime $p>2$ both with constant and Burnside ring coefficients. The authors
+first proved it for $p=3$ and then the second author generalized it to
+arbitrary $p$. These are the first such calculations for a non-abelian group.",2005.01225v1
+2020-06-08,Weighted sums of generalized polygonal numbers with coefficients 1 or 2,"In this article, we consider weighted sums of generalized polygonal numbers
+with coefficients $1$ or $2$. We show that for any $m\ge10$, those weighted
+sums of generalized $m$-gonal numbers represent every non-negative integers if
+they only represent $1$, $m-4$, and $m-2$. Furthermore, we study
+representations of sums of four generalized polygonal numbers with coefficients
+$1$ or $2$.",2006.04490v2
+2020-11-20,Notes on equivariant homology with constant coefficients,"In this paper, for a finite group, we discuss a method for calculating
+equivariant homology with constant coefficients. We apply it to completely
+calculate the geometric fixed points of the equivariant spectrum representing
+equivariant (co)homology with constant coefficients. We also treat a more
+complicated example of inverting the standard representation in the equivariant
+homology of split extraspecial groups at the prime 2.",2011.10622v1
+2020-11-24,A generalized Montel theorem for a class of first order elliptic equations with measurable coefficients,"In this paper we prove a generalization of Montel's theorem for a class of
+first order elliptic equations with measurable coefficients involving
+Hodge-Dirac operators. We then apply this result to sequences of solutions of
+second order uniformly elliptic equations with measurable coefficients on
+divergence form and show that this results in a precompactness result for such
+sequences.",2011.12185v1
+2020-11-24,Homological Polynomial Coefficients and the Twist Number of Alternating Surface Links,"For $D$ a reduced alternating surface link diagram, we bound the twist number
+of $D$ in terms of the coefficients of a polynomial invariant. To this end, we
+introduce a generalization of the homological Kauffman bracket defined by
+Krushkal. Combined with work of Futer, Kalfagianni, and Purcell, this yields a
+bound for the hyperbolic volume of a class of alternating surface links in
+terms of these coefficients.",2011.12274v1
+2020-12-30,Matrix products of binomial coefficients and unsigned Stirling numbers,"We study sums of the form $\sum_{k=m}^n a_{nk} b_{km}$, where $a_{nk}$ and
+$b_{km}$ are binomial coefficients or unsigned Stirling numbers. In a few cases
+they can be written in closed form. Failing that, the sums still share many
+common features: combinatorial interpretations, Pascal-like recurrences,
+inverse relations with their signed versions, and interpretations as
+coefficients of change between polynomial bases.",2012.15307v1
+2021-01-09,Transience of symmetric non-local Dirichlet forms,"We establish transience criteria for symmetric non-local Dirichlet forms on
+$L^2({\mathbb R}^d)$ in terms of the coefficient growth rates at infinity.
+Applying these criteria, we find a necessary and sufficient condition for
+recurrence of Dirichlet forms of symmetric stable-like with
+unbounded/degenerate coefficients. This condition indicates that both of the
+coefficient growth rates of small and big jump parts affect the sample path
+properties of the associated symmetric jump processes.",2101.03442v2
+2021-03-06,Estimates for Green's functions of elliptic equations in non-divergence form with continuous coefficients,"We present a new method for the existence and pointwise estimates of a
+Green's function of non-divergence form elliptic operator with Dini mean
+oscillation coefficients. We also present a sharp comparison with the
+corresponding Green's function for constant coefficients equations.",2103.04071v2
+2021-04-14,Inverse Boundary Problem for the Two Photon Absorption Transport Equation,"This work studies the inverse boundary problem for the two photon absorption
+radiative transport equation. We show that the absorption coefficients and
+scattering coefficients can be uniquely determined from the \emph{albedo}
+operator. If scattering is absent, we do not require smallness of the incoming
+source and the reconstructions of the absorption coefficients are explicit.",2104.06566v2
+2021-04-23,Stochastic differential equations with irregular coefficients:~mind the gap!,"Numerical methods for stochastic differential equations with non-globally
+Lipschitz coefficients are currently studied intensively. This article gives an
+overview of our work for the case that the drift coefficient is potentially
+discontinuous complemented by other important results in this area. To make the
+topic accessible to a broad audience, we begin with a heuristic on SDEs and a
+motivation.",2104.11505v1
+2021-06-04,Rademacher-Gaussian tail comparison for complex coefficients and related problems,"We provide a generalisation of Pinelis' Rademacher-Gaussian tail comparison
+to complex coefficients. We also establish uniform bounds on the probability
+that the magnitude of weighted sums of independent random vectors uniform on
+Euclidean spheres with matrix coefficients exceeds its second moment.",2106.02421v1
+2021-08-25,A note on Chern coefficients and Cohen-Macaulay rings,"In this paper, we investigate the relationship between the index of
+reducibility and Chern coefficients for primary ideals. As an application, we
+give characterizations of a Cohen-Macaulay ring in terms of its type,
+irreducible multiplicity, and Chern coefficients with respect to certain
+parameter ideals in Noetherian local rings.",2108.11079v1
+2021-09-19,Dirichlet series and series with Stirling numbers,"This paper presents a number of identities for Dirichlet series and series
+with Stirling numbers of the first kind. As coefficients for the Dirichlet
+series we use Cauchy numbers of the first and second kinds, hyperharmonic
+numbers, derangement numbers, binomial coefficients, central binomial
+coefficients, and Catalan numbers.",2109.09167v3
+2021-11-14,On the coefficients of the distinct monomials in the expansion of $x_1(x_1+x_2)\cdots(x_1+x_2+\cdots+x_n)$,"We initiate the study of the coefficients of the distinct monomials in the
+expansion of the multivariate polynomials
+$x_1(x_1+x_2)\cdots(x_1+x_2+\cdots+x_n), n\in\N$. In particular we obtain
+several results regarding their maximal coefficients.",2111.07331v3
+2021-12-16,Split link detection for sl(P) link homology in characteristic P,"If $P$ is a prime number, we show that reduced $\mathfrak{sl}(P)$ link
+homology with coefficients in $\mathbf{Z}/P$ detects split links. The argument
+uses Dowlin's spectral sequence and sutured Floer homology with twisted
+coefficients. When $P = 2$, we recover Lipshitz-Sarkar's split link detection
+result for Khovanov homology with $\mathbf{Z}/2$ coefficients.",2112.09110v2
+2022-01-17,On Hochschild homology of uniform Roe algebras with coefficients in uniform Roe bimodules,"It was shown recently by M. Lorentz and R. Willett that all bounded
+derivations of the uniform Roe algebras of metric spaces of bounded geometry
+are inner. Here we calculate the space of outer derivations of the uniform Roe
+algebras with coefficients in uniform Roe bimodules related to various metrics
+on the two copies of the given space. We also give some results on the higher
+Hochschild cohomology with coefficients in uniform Roe bimodules.",2201.06488v1
+2022-02-21,Maximum principle for time-fractional parabolic equations with a reaction coefficient of arbitrary sign,"We consider time-fractional parabolic equations with a Caputo time derivative
+of order $\alpha\in(0,1)$. For such equations, we give an elementary proof of
+the weak maximum principle under no assumptions on the sign of the reaction
+coefficient. This proof is also extended for weak solutions, as well as for
+various types of boundary conditions and variable-coefficient variable-order
+multiterm time-fractional parabolic equations.",2202.10220v2
+2022-05-13,Discrete m-functions with Doubly Palindromic Continued Fraction Coefficients,"We demonstrate that discrete m-functions with eventually periodic continued
+fraction coefficients have an algebraic relationship to their second solution
+if and only if the periodic part of the sequence of continued fraction
+coefficients is doubly palindromic. In this setting, doubly palindromic means
+that each sequence is a repeated concatenation of two palindromes and a
+compatibility condition between the lengths of these palindromes is satisfied.",2205.06653v1
+2022-06-21,Lipschitz Continuity for Elliptic Free Boundary Problems with Dini Mean Oscillation Coefficients,"We establish local interior Lipschitz continuity of the solutions of a class
+of free boundary elliptic problems assuming the coefficients of the equation of
+Dini mean oscillation in at least one direction. The novelty in this regularity
+result lies in the fact that it allows discontinuous coefficients in all but
+one variable.",2206.10239v1
+2022-06-30,Yet another proof that the roots of a polynomial depend continuously on the coefficients,"The roots of a complex polynomial depend continuously on the coefficients;
+that is, an infinitesimal perturbation of the coefficients results in an
+infinitesimal perturbation of the roots. A short, straightforward proof of this
+is possible using infinitesimals.",2207.00123v2
+2022-07-20,Recovery of coefficients in semilinear transport equations,"We consider the inverse problem for time-dependent semilinear transport
+equations. We show that time-independent coefficients of both the linear
+(absorption or scattering coefficients) and nonlinear terms can be uniquely
+determined, in a stable way, from the boundary measurements by applying a
+linearization scheme and Carleman estimates for the linear transport equations.
+We establish results in both Euclidean and general geometry settings.",2207.10194v1
+2022-09-21,Finite polynomial cohomology with coefficients,"We introduce a theory of finite polynomial cohomology with coefficients in
+this paper. We prove several basic properties and introduce an Abel-Jacobi map
+with coefficients. As applications, we use such a cohomology theory to study
+arithmetics of compact Shimura curves over $\mathbb{Q}$, and simplify proofs of
+the works of Darmon-Rotger and Bertolini-Darmon-Prasanna.",2209.10289v2
+2022-09-30,Independence of Linear Statistics with Random Coefficients and Characterizations of Geometric and Poisson Distributions,"There is given a characterization of the geometric distribution by the
+independence of linear forms with random coefficients. The result is a discrete
+analog of the corresponding theorem on exponential distribution. The property
+of linear statistics independence is also a characterization of Poisson law.
+Keywords: geometric distribution; exponential distribution; Poisson
+distribution; linear forms; random coefficients",2210.01121v1
+2022-08-26,Integral operator on certain subclass of analytic function with negative coefficients,"In this paper, we study subclass of analytic function with negative
+coefficient defined by integral operator in the unit disc $U = \left\{ {z \in
+C:\left| z \right| < 1} \right\}$. The results are included coefficient
+estimates, closure theorem and distortion theorems of functions belonging to
+this subclass. Also, we presented detailed study of uniformly convex and
+uniformly starlike functions.",2211.06422v1
+2022-11-23,The first negative Fourier coefficient of an Eisenstein series newform,"There have been a number of papers on statistical questions concerning the
+sign changes of Fourier coefficients of newforms. In one such paper, Linowitz
+and Thompson gave a conjecture describing when, on average, the first negative
+sign of the Fourier coefficients of an Eisenstein series newform occurs. In
+this paper, we correct their conjecture and prove the corrected version.",2211.12985v2
+2023-01-16,Factorization of certain Macdonald Littlewood-Richardson coefficients,"We find and prove a factorization formula for certain Macdonald
+Littlewood-Richardson coefficients $c_{\lambda\mu}^{\nu}(q,t)$. Namely, we
+consider the case that the Kostka number $K_{\mu, \nu -\lambda}$ is $1$. This
+settles a particular case of a more general conjecture of Richard Stanely. This
+conjecture proposes that a factorization formula exists whenever the
+corresponding regular Littlewood-Richardson coefficient $c^{\nu}_{\lambda \mu}$
+is $1$.",2301.06500v1
+2023-02-14,Eigenvalue location of certain matrix polynomials,"It is known that a matrix polynomial with unitary matrix coefficients has its
+eigenvalues in the annular region $\frac{1}{2} < |\lambda| < 2$. We prove in
+this short note that under certain assumptions, matrix polynomials with either
+doubly stochastic matrix coefficients or Schur stable matrix coefficients also
+have eigenvalues in similar annular regions.",2302.06788v1
+2023-02-16,Continuous group cohomology with coefficients in locally analytic vectors of admissible $ \mathbb{Q}_p $-Banach space representations,"We show that the continuous cohomology groups of a $ p $-adic reductive group
+with coefficients in the locally analytic vectors of an admissible $
+\mathbb{Q}_p $-Banach space representation are homeomorphic to those with
+coefficients in the Banach space representation itself. Moreover, we deduce
+that the canonical topologies on those continuous cohomology groups are
+Hausdorff and are the uniquely determined finest locally convex topologies.",2302.08369v1
+2023-02-23,On the spectrum of the differential operators of even order with periodic matrix coefficients,"In this paper, we consider the band functions, Bloch functions and spectrum
+of the self-adjoint differential operator L with periodic matrix coefficients.
+Conditions are found for the coefficients under which the number of gaps in the
+spectrum of the operator L is finite",2302.11807v1
+2023-07-05,A remark on the quantum complexity of the Kronecker coefficients,"We prove that the computation of the Kronecker coefficients of the symmetric
+group is contained in the complexity class #BQP. This improves a recent result
+of Bravyi, Chowdhury, Gosset, Havlicek, and Zhu. We use only the quantum
+computing tools that are used in their paper and additional classical
+representation theoretic insights. We also prove the analogous result for the
+plethysm coefficients.",2307.02389v1
+2023-08-31,An extension of Lucas Theorem,"We give elementary proofs of some congruence criteria to compute binomial
+coefficients in modulo a prime. These criteria are analogues to the symmetry
+property of binomial coefficients. We give extended version of Lucas Theorem by
+using those criteria. We give applications of these criteria by describing a
+method to derive identities and congruences involving sums of binomial
+coefficients.",2309.00109v1
+2023-09-11,On the Cauchy problem for $p$-evolution equations with variable coefficients: a necessary condition for Gevrey well-posedness,"In this paper we consider a class of $p$-evolution equations of arbitrary
+order with variable coefficients depending on time and space variables $(t,x)$.
+We prove necessary conditions on the decay rates of the coefficients for the
+well-posedness of the related Cauchy problem in Gevrey spaces.",2309.05571v1
+2023-09-22,On the $ψ$-mixing coefficients of Rényi-type maps,"Via dependence with complete connections we investigate the $\psi$-mixing
+coefficients of the sequence $(a_n)_{n \in \mathbb{N}}$ of incomplete quotients
+and also of the doubly infinite sequence $(\overline{a}_l)_{l \in \mathbb{Z}}$
+of extended incomplete quotients of the R\'enyi-type continued fraction
+expansions. A L\'evy-type approach allows us to obtain good upper bounds for
+these coefficients.",2309.12649v1
+2023-10-13,Convexification for a Coefficient Inverse Problem of Mean Field Games,"The globally convergent convexification numerical method is constructed for a
+Coefficient Inverse Problem for the Mean Field Games System. A coefficient
+characterizing the global interaction term is recovered from the single
+measurement data. In particular, a new Carleman estimate for the Volterra
+integral operator is proven, and it stronger than the previously known one.
+Numerical results demonstrate accurate reconstructions from noisy data.",2310.08878v1
+2023-10-19,Stable recovery of coefficients in an inverse fault friction problem,"We consider the inverse fault friction problem of determining the friction
+coefficient in the Tresca friction model, which can be formulated as an inverse
+problem for differential inequalities. We show that the measurements of elastic
+waves during a rupture uniquely determine the friction coefficient at the
+rupture surface with explicit stability estimates.",2310.12698v1
+2023-11-06,Hilbert coefficients of quadratic algebras,"If $R=k[x_1,\ldots,x_n]/I$ is a graded artinian algebra, then the length of
+$k[x_1,\ldots,x_n]/I^s$ becomes a polynomial in $s$ of degree $n$ for large
+$s$. If we write this polynomial as $\sum_{i=0}^n(-1)^ie_i{s+n-i-1\choose
+n-i}$, then the $e_i$'s are called Hilbert coefficients of $I$. We will study
+length and Hilbert coefficients of some classes of quadratic algebras.",2311.02860v1
+2023-12-05,On pair correlation of Hermite coefficients of functions from the Hardy class,"Assuming that a function and its Fourier transform are dominated by a
+Gaussian, Vemuri found a sharp estimate for the decay rate of the Hermite
+coefficients in terms of the variance of the dominating Gaussian. Here we show
+that under the same assumptions, certain combinations of Hermite coefficients
+have a better rate of decay.",2312.02606v1
+2024-01-01,Walsh coefficients and circuits for several alleles,"Walsh coefficients have been applied extensively to biallelic systems for
+quantifying pairwise and higher order epistasis, in particular for
+demonstrating the empirical importance of higher order interactions. Circuits,
+or minimal dependence relations, and related approaches that use triangulations
+of polytopes have also been applied to biallelic systems. Here we provide
+biological interpretations of Walsh coefficients for several alleles, and
+discuss circuits in the same general setting.",2401.00743v2
+2024-01-02,Comment on `Index-free Heat Kernel Coefficients',"The article by Anton E. M. van de Ven, Class. Quantum Grav. \textbf{15}
+(1998), is one of the fundamental references for higher-order heat kernel
+coefficients in curved backgrounds and with non-abelian gauge connections. In
+this manuscript, we point out two errors and ambiguities in the $\mathsf{a}_5$
+coefficient, which may also affect the higher-order ones.",2401.01296v1
+2024-01-19,Some coefficient estimates on complex valued kernel $α$-harmonic mappings,"We call a kind of mappings induced by a kind of weighted Laplace operator as
+complex valued kernel $\alpha$-harmonic mappings. In this article, for this
+class of mappings, the Heinz type lemma is established, and the best Heinz type
+inequality is obtained. Next, the extremal function of Schwartz's Lemma is
+discussed. Finally, the coefficients are estimated for the subclass of complex
+valued kernel alpha harmonic mappings whose coefficients are real numbers.",2401.10434v1
+2024-01-24,Optimal regularity for the variable coefficients parabolic Signorini problem,"In this paper we discuss the optimal regularity of the variable coefficient
+parabolic Signorini problem with $W^{1,1}_p$ coefficients and $L^p$
+inhomogeneity, where $p>n+2$ with $n$ being the space dimension. Relying on an
+parabolic Carleman estimate and an epiperimetric inequality, we show the
+optimal regularity of the solutions as well as the regularity of the regular
+free boundary.",2401.13305v1
+2024-03-24,Determination of Hilbert modular forms using squarefree coefficients,"Let $F$ (over $\mathbb{Q}$) be a totally real number field of narrow class
+number $1$. We generalize a result of Kohnen on the determination of half
+integral weight modular forms by their Fourier coefficients supported on
+squarefree (algebraic) integers. We also give a soft proof that infinitely many
+Fourier coefficients supported on squarefree integers are non-vanishing.",2403.16012v1
+1994-02-17,Power Spectrum Constraints from Spectral Distortions in the Cosmic Microwave Background,"%The content of this replacement paper is identical to the original. %We have
+attempted to fix the postscript so that it will print out on %a larger number
+of printers. Using recent experimental limits on $\mu$ distortions from COBE
+FIRAS, and the large lever-arm spanning the damping of sub-Jeans scale
+fluctuations to the scale of the COBE DMR fluctuations, we set a constraint on
+the slope of the primordial power spectrum $n$. It is possible to analytically
+calculate the contribution over the full range of scales and redshifts,
+correctly taking into account fluctuation growth and damping as well as
+thermalization processes. We find that the 95\% upper limit is weakly dependent
+on cosmological parameters, e.g. $n<1.54 (h=0.5)$ and $n<1.56 (h=1.0)$ for
+$\Omega_0=1$ with marginally weaker constraints for $\Omega_0<1$ in a flat
+$\Omega_0 +\Omega_\Lambda=1$ universe.",9402045v2
+1995-06-01,The epoch of structure formation in blue mixed dark matter models,"Recent data on the high--redshift abundance of damped Ly$\alpha$ systems are
+compared with theoretical predictions for `blue' (i.e. $n>1$) Mixed Dark Matter
+models. The results show that decreasing the hot component fraction
+$\Omega_\nu$ and/or increasing the primordial spectral index $n$ implies an
+earlier epoch of cosmic structure formation. However, we also show that varying
+$\Omega_\nu$ and $n$ in these directions makes the models barely consistent
+with the observed abundance of galaxy clusters. Therefore, requiring at the
+same time observational constraints on damped Ly$\alpha$ systems and cluster
+abundance to be satisfied represents a challenge for the Mixed Dark Matter
+class of models.",9506003v2
+1996-04-16,Cosmic Emissivity and Background Intensity from Damped Lyman-Alpha Galaxies,"We present a new method to compute the cosmic emissivity $\E_\nu$ and
+background intensity $J_\nu$. Our method is based entirely on data from quasar
+absorption-line studies, namely, the comoving density of HI and the mean
+metallicity and dust-to-gas ratio in damped Ly$\alpha$ galaxies. These
+observations, when combined with models of cosmic chemical evolution, are
+sufficient to determine the comoving rate of star formation as a function of
+redshift. From this, we compute $\E_\nu $ and $J_\nu$ using stellar population
+synthesis models. Our method includes a self-consistent treatment of the
+absorption and reradiation of starlight by dust. In all of our calculations,
+the near-UV emissivity declines rapidly between $z\approx1$ and $z=0$, in
+agreement with estimates from the Canada-France Redshift Survey. The background
+intensity is consistent with a wide variety of observational limits and with a
+tentative detection at far-IR wavelengths.",9604091v1
+1996-05-24,Identification of a Galaxy Responsible for a High-Redshift Damped Ly-alpha Absorption System,"Galaxies believed to be responsible for damped Ly-alpha absorption (DLA)
+systems in the spectra of high-redshift quasars represent a viable population
+of progenitors of normal disk galaxies. They appear to contain a substantial
+fraction of the baryons known to exist in normal galaxies today. Here we report
+on the detection of an object, designated DLA 2233+131, responsible for a
+previously known DLA system at z(abs)=3.150 in the spectrum of a quasar
+2233+131 [z(QSO)=3.295]. This is the first unambiguous detection of a DLA
+galaxy, in both emission line and stellar continuum. Its properties correspond
+closely to what may be expected from a young disk galaxy in the early stages of
+formation, with no sign of an active nucleus. This gives a strong support to
+the idea that DLA systems represent a population of young galaxies at high
+redshifts.",9605154v1
+1996-10-18,The absorbers towards Q0836+113,"We have performed RIJHK_S imaging of the field around the z=2.67 quasar
+Q0836+113, which presents several metal line and a damped Ly\alpha absorption
+systems in its spectrum. The images reveal the existence of a red K_S=18.9
+object \approx 11 arcsec from the quasar. On the basis of the empirical
+relationships between absorption radius and luminosity we conclude that this
+object may be the CIV absorber at z=1.82. This could be the first detection of
+a high redshift galaxy causing high-ionisation absorption. After carefully
+subtracting the QSO, we do not detect, up to a 3\sigma limiting magnitude for
+extended objects of K_S=20.8, the damped Ly\alpha absorber apparently detected
+as a Ly\alpha emitter at z=2.47. It is also suggested, that object ``SW'' from
+Wolfe et al. (1992) could be the galaxy responsible for the claimed MgII
+absorption at z=0.37.",9610141v1
+1996-12-13,The 67 Hz Feature in the Black Hole Candidate GRS 1915+105 as a Possible ``Diskoseismic'' Mode,"The Rossi X-ray Timing Explorer (RXTE) has made feasible for the first time
+the search for high-frequency (~ 100 Hz) periodic features in black hole
+candidate (BHC) systems. Such a feature, with a 67 Hz frequency, recently has
+been discovered in the BHC GRS 1915+105 (Morgan, Remillard, & Greiner). This
+feature is weak (rms variability ~0.3%-1.6%), stable in frequency (to within ~2
+Hz) despite appreciable luminosity fluctuations, and narrow (quality factor Q ~
+20). Several of these properties are what one expects for a ``diskoseismic''
+g-mode in an accretion disk about a 10.6 M_sun (nonrotating) - 36.3 M_sun
+(maximally rotating) black hole (if we are observing the fundamental mode
+frequency). We explore this possibility by considering the expected luminosity
+modulation, as well as possible excitation and growth mechanisms---including
+turbulent excitation, damping, and ``negative'' radiation damping. We conclude
+that a diskoseismic interpretation of the observations is viable.",9612142v2
+1997-01-15,Gravitational Lensing of Quasars by Spiral Galaxies,"Gravitational lensing by a spiral galaxy occurs when the line-of-sight to a
+background quasar passes within a few kpc from the center of the galactic disk.
+Since galactic disks are rich in neutral hydrogen, the quasar spectrum will
+likely be marked by a damped Lyman-alpha absorption trough at the lens
+redshift. Therefore, the efficiency of searches for gravitational lensing with
+sub-arcsecond splitting can be enhanced by 1-2 orders of magnitude by focusing
+on a subset of all bright quasars which show low-redshift (z<1) strong
+Lyman-alpha absorption (N>10^{21} cm^{-2}}). The double-image signature of
+lensing could, in principle, be identified spectroscopically and without the
+need for high-resolution imaging. The absorption spectrum of a spiral lens
+would show a generic double-step profile due to the superposition of the two
+absorption troughs of the different images. Finally, we note that searches for
+microlensing signatures of quasars with damped Lyman-alpha absorption could
+calibrate the fraction of MACHOs in galactic halos at high redshift.",9701100v1
+1997-02-27,Interacting Hot Dark Matter,"We discuss the viability of a light particle ($\sim 30$ eV neutrino) with
+strong self-interactions as a dark matter candidate. The interaction prevents
+the neutrinos from free-streaming during the radiation dominated regime so
+galaxy sized density perturbations can survive. Smaller scale perturbations are
+damped due to neutrino diffusion. We calculate the power spectrum in the
+imperfect fluid approximation, and show that it is damped at the length scale
+one would estimate due to neutrino diffusion. The strength of the
+neutrino--neutrino coupling is only weakly constrained by observations, and
+could be chosen by fitting the power spectrum to the observed amplitude of
+matter density perturbations. The main shortcoming of our model is that
+interacting neutrinos can not provide the dark matter in dwarf galaxies.",9702236v1
+1997-05-20,Detection of the First Star Clusters With NGST,"We calculate the observable signatures of the first generation of stars at
+high redshift (5<z<100). To determine the cosmic star-formation history, we use
+an extension of the Press-Schechter formalism for Cold Dark Matter (CDM)
+cosmologies that incorporates gas pressure. We calibrate the fraction of gas
+converted into stars to be 6% so as to reproduce the 1% solar C/H ratio
+observed in the intergalactic medium (IGM) at z=3. With this star-formation
+efficiency, we find that NGST would be able to image more than 10^4 star
+clusters from high redshifts (z>10) within its 4'x4' field of view. If stars
+occupy a region comparable to the virial radius of the cluster, then 1% of
+these clusters could be resolved. We calculate the expected number-flux
+relation and angular size distribution for these early star clusters. We also
+describe the reionization of the IGM due to the first generation of stars, and
+the consequent damping of the CMB anisotropies on small angular scales. This
+damping could be detected below 10 degree angular scales by MAP and PLANCK.",9705144v1
+1997-09-12,Baryonic Features in the Matter Transfer Function,"We provide scaling relations and fitting formulae for adiabatic cold dark
+matter cosmologies that account for all baryon effects in the matter transfer
+function to better than 10% in the large-scale structure regime. They are based
+upon a physically well-motivated separation of the effects of acoustic
+oscillations, Compton drag, velocity overshoot, baryon infall, adiabatic
+damping, Silk damping, and cold-dark-matter growth suppression. We also find a
+simpler, more accurate, and better motivated form for the zero baryon transfer
+function than previous works. These descriptions are employed to quantify the
+amplitude and location of baryonic features in linear theory. While baryonic
+oscillations are prominent if the baryon fraction exceeds $\Omega_0 h^2 + 0.2$,
+the main effect in more conventional cosmologies is a sharp suppression in the
+transfer function below the sound horizon. We provide a simple but accurate
+description of this effect and stress that it is not well approximated by a
+change in the shape parameter $\Gamma$.",9709112v1
+1997-09-23,Nonlinear spherical Alfven waves,"We present an one-dimensional numerical study of Alfven waves propagating
+along a radial magnetic field. Neglecting losses, any spherical Alfven wave, no
+matter how small its initial amplitude is, becomes nonlinear at sufficiently
+large radii. From previous simulations of Alfven waves in plane parallel
+atmospheres we did expect the waves to steepen and produce current sheets in
+the nonlinear regime, which was confirmed by our new calculations. On the other
+hand we did find that even the least nonlinear waves were damped out almost
+completely before 10 solar radii. A damping of that kind is required by models
+of Alfven wave-driven winds from old low-mass stars as these winds are mainly
+accelerated within a few stellar radii.",9709222v1
+1997-12-10,Effects of Disks on Gravitational Lensing by Spiral Galaxies,"Gravitational lensing of a quasar by a spiral galaxy should often be
+accompanied by damped Lyman-alpha absorption and dust extinction due to the
+intervening gaseous disk. In nearly edge-on configurations, the surface mass
+density of the gas and stars in the disk could by itself split the quasar image
+and contribute significantly to the overall lensing cross section. We calculate
+the lensing probability of a disk+halo mass model for spiral galaxies,
+including cosmic evolution of the lens parameters. A considerable fraction of
+the lens systems contains two images with sub-arcsecond separation, straddling
+a nearly edge-on disk. Because of that, extinction by dust together with
+observational selection effects (involving a minimum separation and a maximum
+flux ratio for the lensed images), suppress the detection efficiency of spiral
+lenses in optical wavebands by at least an order of magnitude. The missing
+lenses could be recovered in radio surveys. In modifying the statistics of
+damped Lyman-alpha absorbers, the effect of extinction dominates over the
+magnification bias due to lensing.",9712138v1
+1998-03-20,HI 21cm absoprtion in two low redshift damped Ly-alpha systems,"We report the discovery of two low redshift HI 21cm absorbers, one at z =
+0.2212 towards the z_{em} = 0.630 quasar OI 363 (B0738+313), and the other at z
+= 0.3127 towards PKS B1127-145 (z_{em} = 1.187). Both were found during a
+survey of MgII selected systems at redshifts 0.2 < z < 1 using the new UHF-high
+system at the Westerbork Synthesis Radio Telescope (WSRT). New HST/FOS
+observations also identify both systems as damped Ly-alpha (DLa) absorbers. By
+comparing the column density from the DLa line with that from the HI 21cm line,
+we calculate the spin temperature, and find that T_s is approximately 1000 K
+for both of these low redshift absorbers. We briefly discuss some implications
+of this result.",9803243v1
+1998-05-08,Infrared emission-line galaxies associated with damped Lyman-alpha and strong metal absorber redshifts,"Eighteen candidates for emission line galaxies were discovered in a
+narrow-band infrared survey that targeted the redshifts of damped Lyman-alpha
+or metal lines in the spectra of quasars. The presence of emission lines is
+inferred from the photometric magnitudes in narrow and broad band interference
+filters, corresponding to H-alpha at redshifts of 0.89 (6 objects) and 2.4 (10
+objects), and [OII] at a redshift of 2.3 (2 objects). Most of the candidates
+are small resolved objects, compatible with galaxies at the redshifts of the
+absorbers. Because a similar survey targeted at the redshifts of quasars
+themselves uncovered only one emission-line galaxy in a larger volume, the
+results imply substantial clustering of young galaxies or formation within
+filaments or sheets whose locations are indicated by the redshifts of strong
+absorption along the lines of sight to more distant quasars.",9805103v1
+1998-05-12,Resonant Thickening of Disks by Small Satellite Galaxies,"We study the vertical heating and thickening of galaxy disks due to accretion
+of small satellites. Our simulations are restricted to axial symmetry, which
+largely eliminates numerical evolution of the target galaxy but requires the
+trajectory of the satellite to be along the symmetry axis of the target. We
+find that direct heating of disk stars by the satellite is not important
+because the satellite's gravitational perturbation has little power at
+frequencies resonant with the vertical stellar orbits. The satellite does
+little damage to the disk until its decaying orbit resonantly excites
+large-scale disk bending waves. Bending waves can damp through dynamical
+friction from the halo or internal wave-particle resonances; we find that
+wave-particle resonances dominate the damping. The principal vertical heating
+mechanism is therefore dissipation of bending waves at resonances with stellar
+orbits in the disk. Energy can thus be deposited some distance from the point
+of impact of the satellite. The net heating from a tightly bound satellite can
+be substantial, but satellites that are tidally disrupted before they are able
+to excite bending waves do not thicken the disk.",9805145v1
+1998-09-14,Collisionless Relaxation of Stellar Systems,"The objective of the work summarised here has been to exploit and extend
+ideas from plasma physics and accelerator dynamics to formulate a unified
+description of collisionless relaxation that views violent relaxation, Landau
+damping, and phase mixing as (manifestations of) a single phenomenon. This
+approach embraces the fact that the collisionless Boltzmann equation (CBE), the
+basic object of the theory, is an infinite-dimensional Hamiltonian system, with
+the distribution function f playing the role of the fundamental dynamical
+variable, and that, interpreted appropriately, an evolution described by the
+{\it CBE} is no different fundamentally from an evolution described by any
+other Hamiltonian system. Equilibrium solutions correspond to extremal points
+of the Hamiltonian subject to the constraints associated with Liouville's
+Theorem. Stable equilibria correspond to energy minima. The evolution of a
+system out of equilibrium involves (in general nonlinear) phase space
+oscillations which may -- or may not -- interfere destructively so as to damp
+away.",9809178v1
+1998-09-30,Discovery of a z=0.808 damped Lyman-alpha system candidate in a UV selected quasar spectrum,"We present the observation of a new intermediate redshift damped Lyman-alpha
+absorption system candidate, discovered in the course of a spectroscopic
+follow-up for identifying the sources detected in a 150 A wide bandpass
+UV-imaging survey at 2000 A. The system displays very strong MgII and FeII
+lines and a high FeII/MgII ratio, which, following photoionization models,
+indicates a very high neutral hydrogen column density. Such kind of systems
+being very rare at redshifts <1.7, but of prime importance for understanding
+the evolution of star formation in galaxies, the newly discovered candidate
+deserves further investigations in a near future",9809402v1
+1998-10-02,Gravity-modes in ZZ Ceti Stars. II. Effects of Turbulent Dissipation,"We investigate dynamical interactions between turbulent convection and g-mode
+pulsations in ZZ Ceti variables (DAVs). Since our understanding of turbulence
+is rudimentary, we are compelled to settle for order of magnitude results. A
+key feature of these interactions is that convective response times are much
+shorter than pulsation periods. Thus the dynamical interactions enforce near
+uniform horizontal velocity inside the convection zone. They also give rise to
+a narrow shear layer in the region of convective overshoot at the top of the
+radiative interior. Turbulent damping inside the convection zone is negligible
+for all modes, but that in the region of convective overshoot may be
+significant for a few long period modes near the red edge of the instability
+strip. These conclusions are in accord with those reached earlier by Brickhill.
+Our major new result concerns nonlinear damping arising from the
+Kelvin-Helmholtz instability of the aforementioned shear layer. Amplitudes of
+overstable modes saturate where dissipation due to this instability balances
+excitation by convective driving. This mechanism of amplitude saturation is
+most effective for long period modes, and it may play an important role in
+defining the red edge of the instability strip.",9810038v1
+1999-02-11,Element Abundances at High Redshifts,"I review measurements of element abundances in different components of the
+high redshift universe, including the Lyman alpha forest, damped Lyman alpha
+systems, and Lyman break galaxies. Although progress is being made in all three
+areas, recent work has also produced some surprises and shown that established
+ideas about the nature of the damped Lyman alpha systems in particular may be
+too simplistic. Overall, our knowledge of metal abundances at high z is still
+very sketchy. Most significantly, there seems to be an order of magnitude
+shortfall in the comoving density of metals which have been measured up to now
+compared with those produced by the star formation activity seen in Lyman break
+galaxies. At least some of the missing metals are likely to be in hot gas in
+galactic halos and proto-clusters.",9902173v1
+1999-03-09,Numerical simulation of prominence oscillations,"We present numerical simulations, obtained with the Versatile Advection Code,
+of the oscillations of an inverse polarity prominence. The internal prominence
+equilibrium, the surrounding corona and the inert photosphere are well
+represented. Gravity and thermodynamics are not taken into account, but it is
+argued that these are not crucial. The oscillations can be understood in terms
+of a solid body moving through a plasma. The mass of this solid body is
+determined by the magnetic field topology, not by the prominence mass proper.
+The model also allows us to study the effect of the ambient coronal plasma on
+the motion of the prominence body. Horizontal oscillations are damped through
+the emission of slow waves while vertical oscillations are damped through the
+emission of fast waves.",9903128v1
+1999-03-26,Nature and evolution of Damped Lyman alpha systems,"The main properties of Damped Lyman alpha (DLA) systems are briefly reviewed
+with the aim of studying the nature and evolution of the galaxies associated
+with this class of QSO absorbers. Candidate DLA galaxies identified at z </= 1
+in the fields of background QSOs show a variety of morphological types without
+a predominance of spirals. Most properties inferred from spectroscopic studies
+at z >/= 1.65 differ from those expected for spiral galaxies. The observational
+results instead suggest that a significant fraction of DLA systems originate in
+low-mass and/or LSB galaxies. Evolution effects are generally not detected in
+DLA systems. This fact suggests that the differences between the properties of
+present-day spirals and those of high-z DLA systems may not be ascribed to
+evolution. Several selection effects can bias the observed population of DLA
+absorbers. Analysis of these effects indicates that the fraction of spiral
+galaxies tends to be underestimated relative to the fraction of low-mass or LSB
+galaxies.",9903406v1
+1999-11-03,Tensor Microwave Anisotropies from a Stochastic Magnetic Field,"We derive an expression for the angular power spectrum of cosmic microwave
+background anisotropies due to gravity waves generated by a stochastic magnetic
+field and compare the result with current observations; we take into account
+the non-linear nature of the stress energy tensor of the magnetic field.
+  For almost scale invariant spectra, the amplitude of the magnetic field at
+galactic scales is constrained to be of order 10^{-9} Gauss. If we assume that
+the magnetic field is damped below the Alfven damping scale, we find that its
+amplitude at
+  0.1 h^{-1}Mpc, B_\lambda, is constrained to be B_\lambda<7.9 x10^{-6} e^{3n}
+Gauss, for n<-3/2, and B_\lambda<9.5x10^{-8} e^{0.37n} Gauss, for n>-3/2, where
+n is the spectral index of the magnetic field and H_0=100h km s^{-1}Mpc^{-1} is
+the Hubble constant today.",9911040v1
+1999-11-09,Viscous Boundary Layer Damping of R-Modes in Neutron Stars,"Recent work has raised the exciting possibility that r-modes (Rossby waves)
+in rotating neutron star cores might be strong gravitational wave sources. We
+estimate the effect of a solid crust on their viscous damping rate and show
+that the dissipation rate in the viscous boundary layer between the oscillating
+fluid and the nearly static crust is >10^5 times higher than that from the
+shear throughout the interior. This increases the minimum frequency for the
+onset of the gravitational r-mode instability to at least 500 Hz when the core
+temperature is less than 10^10 K. It eliminates the conflict of the r-mode
+instability with the accretion-driven spin-up scenario for millisecond radio
+pulsars and makes it unlikely that the r-mode instability is active in
+accreting neutron stars. For newborn neutron stars, the formation of a solid
+crust shortly after birth affects their gravitational wave spin-down and hence
+detectability by ground-based interferometric gravitational wave detectors.",9911155v1
+1999-11-30,The formation and evolution of supermassive black holes and their host galaxies,"We discuss constraints on the assembly history of supermassive black holes
+from the observed remnant black holes in nearby galaxies and from the emission
+caused by accretion onto these black holes. We also summarize the results of a
+specific model for the evolution of galaxies and their central black holes
+which traces their hierachical build-up in CDM-like cosmogonies. The model
+assumes (i) that black holes, ellipticals and starburts form during major
+mergers of galaxies (ii) that the gas fraction in galaxies decreases with
+decreasing redshift (iii) that the optical bright phase of a QSO lasts for
+about 10^7 years. The model succesfully reproduces the evolution of cold gas as
+traced by damped damped Lyman alpha systems, the evolution of optically bright
+QSOs, the remnant black hole mass distribution and the host galaxy luminosities
+of QSOs.",9911514v1
+1999-12-06,The Metallicity evolution of Damped Lyman-alpha systems,"We have collected data for 69 Damped Lyman-alpha (DLA) systems, to
+investigate the chemical evolution of galaxies in the redshift interval 0.0 < z
+< 4.4. In doing that, we have adopted the most general approach used so far to
+correct for dust depletion. The best solution, obtained through chi^2
+minimization, gives as output parameters the global DLA metallicity and the
+dust-to-metals ratio. Clear evolution of the metallicity vs. redshift is found
+(99.99% significance level), with average values going from ~1/30 solar at
+z~4.1 to ~3/5 solar at z~0.5. We also find that the majority of DLAs (~60%)
+shows dust depletion patterns which most closely resemble that of the warm halo
+clouds in the Milky Way, and have dust-to-metals ratios very close to warm halo
+clouds.",9912112v2
+1999-12-22,Alfvenic Heating of Protostellar Accretion Disks,"We investigate the effects of heating generated by damping of Alfven waves on
+protostellar accretion disks. Two mechanisms of damping are investigated,
+nonlinear and turbulent, which were previously studied in stellar winds
+(Jatenco-Pereira & Opher 1989a, b). For the nominal values studied, f=delta
+v/v_{A}=0.002 and F=varpi/Omega_{i}=0.1, where delta v, v_{A} and varpi are the
+amplitude, velocity and average frequency of the Alfven wave, respectively, and
+Omega_{i} is the ion cyclotron frequency, we find that viscous heating is more
+important than Alfven heating for small radii. When the radius is greater than
+0.5 AU, Alfvenic heating is more important than viscous heating. Thus, even for
+the relatively small value of f=0.002, Alfvenic heating can be an important
+source of energy for ionizing protostellar disks, enabling angular momentum
+transport to occur by the Balbus-Hawley instability.",9912478v1
+2000-01-18,Metallicity in damped Lyman-alpha systems: evolution or bias?,"Assuming that damped Lyman-alpha(DLA) systems are galactic discs, we
+calculate the corresponding evolution of metal abundances. We use detailed
+multi-zone models of galactic chemical evolution (reproducing successfully the
+observed properties of disc galaxies) and appropriate statistics (including
+geometrical propability factors) to calculate the average metallicity as a
+function of redshift. The results are compatible with available observations,
+provided that observational biases are taken into account, as suggested by
+Boisse et al. (1998). In particular, high column density and high metallicity
+systems are not detected because the light of backround quasars is severely
+extinguished, while low column density and low metallicity systems are not
+detectable through their absorption lines by current surveys. We show that
+these observational constraints lead to a ``no-evolution'' picture for the DLA
+metallicity, which does not allow to draw strong conclusions about the nature
+of those systems or about their role in ``cosmic chemical evolution''.",0001313v1
+2000-02-24,Optical Counterparts to Damped Lyman Alpha Systems,"Previously we have shown (Maller et al, 1998) that the kinematics of Damped
+Lyman Alpha Systems (DLAS) as measured by Prochaska and Wolfe (1998) can be
+reproduced in a multiple disk model (MDM) if the gaseous disks are of
+sufficient radial extent. Here we discuss this model's predictions for the
+relationship between DLAS and Lyman break galaxies (LBGs), which we here take
+to be objects at z~3 brighter than R=25.5. We expect that future observations
+of the correlations between DLAS and LBGs will provide a new data set able to
+discriminate between different theoretical models of the DLAS. Djorgovski
+(1997) has already detected a few optical counterparts and more studies are
+underway.",0002452v1
+2000-02-24,"Damped Ly-alpha Systems in Semi-Analytic Models: Sensitivity to dynamics, disk properties, and cosmology","Previously we have shown that it is possible to account for the kinematic
+properties of damped Lyman alpha systems (DLAS) in the context of semi-analytic
+models. In these models, hierarchical structure formation is approximated by
+constructing a merger tree for each dark matter halo. A natural consequence is
+that every virialized halo may contain not only a central galaxy, but also a
+number of satellite galaxies as determined by its merging history. Thus the
+kinematics of the DLAS arise from the combined effects of the internal rotation
+of gas disks and the motions between gas disks within a common halo. Here we
+investigate the sensitivity of this model to some of the assumptions made
+previously, including the modeling of satellite dynamics, the scale height of
+the gas, and the cosmology.",0002454v1
+2000-07-31,UVES observations of QSO 0000-2620: Molecular hydrogen abundance in the damped Ly-alpha system at z_abs = 3.3901,"We have discovered molecular hydrogen in a fourth quasar damped Ly-alpha
+system (hereafter DLA). The UVES spectrograph on the 8.2m ESO Kueyen telescope
+has allowed the detection of H2 in gas with low metallicity, Z/Z_solar ~=
+10^{-2}, and high neutral hydrogen column density, N(HI) ~= 2.6*10^{21}
+cm^{-2}, at redshift z_abs = 3.3901 toward QSO 0000-2620. The measured H2
+fractional abundance of f(H2) ~= 4*10^{-8} is lower than a typical value for
+Galactic interstellar clouds of high N(HI) column density by a factor of
+(2-3)*10^6. Since H2 molecules are formed efficiently on dust grains, it
+implies that the dust condensation in this DLA is negligible, and hence the
+abundances derived from metal absorption lines are the actual ones. The
+obtained f(H2) value leads to an estimate of the dust number density of < n_d
+>_DLA ~= 10^{-3}*< n_d >_ISM, which is consistent with the dust-to-gas ratio k
+<= 1.6 10^{-3} derived independently from the [Cr/Zn] and [Fe/Zn] ratios.",0007472v1
+2000-08-11,The Evolution and Space Density of Damped Lyman-alpha Galaxies,"The results of a new spectroscopic survey of 66 $z \simgt 4$ quasars for
+Damped Lyman-alpha absorption systems are presented. The search led to the
+discovery of 30 new DLA candidates which are analysed in order to compute the
+comoving mass density of neutral gas in a non-zero lambda Universe. The
+possible sources of uncertainty are discussed and the implications of our
+results for the theories of galaxy formation and evolution are emphasized. A
+subsequent paper will present details of the calculations summarised here and a
+more extensive explanation of the consequences of our observations for the
+understanding of the nature of DLAs.",0008172v1
+2000-09-06,Damped Lyman-Alpha Galaxies,"Some results from an imaging program to identify low-redshift (0.09<z<1.63)
+damped Lyman-alpha (DLA) galaxies are presented. The standard paradigm that was
+widely accepted a decade ago, that DLA galaxies are the progenitors of luminous
+disk galaxies, is now being seriously challenged. The indisputable conclusion
+from imaging studies at low redshift is that the morphological types of DLA
+galaxies are mixed and that they span a range in luminosities and surface
+brightnesses.",0009096v2
+2000-09-07,On ionisation effects and abundance ratios in damped Lyman-alpha systems,"The similarity between observed velocity structures of Al III and singly
+ionised species in damped Lyman-alpha systems (DLAs) suggests the presence of
+ionised gas in the regions where most metal absorption lines are formed.
+  To explore the possible implications of ionisation effects we construct a
+simplified two-region model for DLAs consisting of an ionisation bounded region
+with an internal radiation field and a neutral region with a lower metal
+content. Within this framework we find that ionisation effects are important.
+If taken into account, the element abundance ratios in DLAs are quite
+consistent with those observed in Milky Way stars and in metal-poor H II
+regions in blue compact dwarf galaxies. In particular we cannot exclude the
+same primary N origin in both DLAs and metal-poor galaxies. From our models no
+dust depletion of heavy elements needs to be invoked; little depletion is
+however not excluded.",0009107v1
+2000-10-20,An Imaging and Spectroscopic Study of the z=3.38639 Damped Lyman Alpha System in Q0201+1120: Clues to Star Formation Rate at High Redshift,"We present the results of a series of imaging and spectroscopic observations
+aimed at identifying and studying the galaxy responsible for the z = 3.38639
+damped lya system in the z = 3.61 QSO Q0201+1120. We find that the DLA is part
+of a concentration of matter which includes at least four galaxies (probably
+many more) over linear comoving dimensions, greater than 5h^-1Mpc. The absorber
+may be a 0.7 L* galaxy at an impact parameter of 15 h^-1 kpc, but follow-up
+spectroscopy is still required for positive identification. The gas is
+turbulent, with many absorption components distributed over approximately 270
+km/s and a large spin temperature, T_s greater than 4000K. The metallicity is
+relatively high for this redshift, Z(DLA) approximately 1/20 Z(solar). From
+consideration of the relative ratios of elements which have different
+nucleosynthetic timescales, it would appear that the last major episode of star
+formation in this DLA occurred at z greater than 4.3, more than approximately
+  500 Myr prior to the time when we observe it.",0010427v1
+2000-10-31,Non-Linear Evolution of the r-Modes in Neutron Stars,"The evolution of a neutron-star r-mode driven unstable by gravitational
+radiation (GR) is studied here using numerical solutions of the full non-linear
+fluid equations. The amplitude of the mode grows to order unity before strong
+shocks develop which quickly damp the mode. In this simulation the star loses
+about 40% of its initial angular momentum and 50% of its rotational kinetic
+energy before the mode is damped. The non-linear evolution causes the fluid to
+develop strong differential rotation which is concentrated near the surface and
+especially near the poles of the star.",0010653v2
+2000-11-07,Damped Lyman-alpha absorption from a nearby Low Surface Brightness galaxy,"Ground-based & HST images of the nearby galaxy SBS 1543+593 (z=0.009) show it
+to be a Low Surface Brightness (LSB) galaxy with a central surface brightness
+of mu_B(0)=23.2 mag/arcsec-2 and scale length 0.9 h-1 kpc, values typical for
+the local LSB galaxy population. The galaxy lies directly in front of the QSO
+HS 1543+5921 (z=0.807); an HST STIS spectrum of the quasar reveals a damped
+Lyman-alpha (DLA) line at the redshift of the interloper with an HI column
+density of log N(HI) = 20.35, as well as several low-ionization metal lines
+with strengths similar to those found in the Milky Way interstellar medium. Our
+data show that LSB galaxies are certainly able to produce the DLA lines seen at
+higher redshift, and fuels the speculation that LSB galaxies are a major
+contributor to that population of absorbers.",0011134v1
+2000-11-25,Molecular hydrogen abundance in the dust-free damped Ly-alpha galaxy at z = 3.4,"New results from the search for H2 absorption in the damped Ly-alpha galaxy
+at redshift z = 3.4 toward QSO 0000-2620 (z_em = 4.1) are reported. The
+high-resolution (lambda/Delta lambda = 48,000) spectra of Q0000-2620 were
+obtained using the Ultraviolet - Visual Echelle Spectrograph (UVES) on the 8.2m
+ESO Kueyen telescope. The ortho-H2 column density is found to be N(J=1) = (5.55
++/- 1.35) 10^{13} cm^{-2} (2sigma C.L.). The combination of N(J=1) with the
+limits available for other low rotational levels restricts the excitation
+temperature T_ex in the range (290-540) K. This gives the total H2 column
+density of N(H2) = (8.75 +/- 1.25) 10^{13} cm^{-2} and the corresponding
+fraction of hydrogen atoms bound in molecules of f(H2) = (6.8 +/- 2.0) 10^{-8}.",0011470v1
+2000-11-25,The Metallicity Evolution of Damped Lyman-alpha Systems,"According to Pei, Fall & Hauser (1999), the global metallicity evolution of
+the Universe can be represented by the ratio of the total metal content to the
+total gas content measured in Damped Lyman-alpha (DLA) systems (the ``column
+density weighted metallicity'' `a la Pettini). To minimize dust obscuration
+effects, a DLA sample with negligible dust content is considered, namely, 50
+DLAs with log N(HI) < 20.8. The global metallicity found shows clear evidence
+of redshift evolution that goes from \sim1/30 solar at z\sim4.1 to solar at z
+\sim 0.4. More generally, DLAs with measured heavy elements probe the ISM of
+high redshift galaxies. The whole sample collected from the literature contains
+75 DLAs. The metallicity is calculated adopting for the dust correction the
+most general method used so far, based on models of the ISM dust depletions in
+the Galaxy. The intrinsic metallicity evolution of DLA galaxies is dlog
+Z(DLA)/dz \propto -0.33 +/- 0.06.",0011473v1
+2000-12-04,ATCA search for 21 cm emission from a candidate damped Ly-$α$ absorber at z = 0.101,"We report a deep search for 21 cm emission/absorption from the $z \sim 0.101$
+candidate damped Lyman-$\alpha$ system towards PKS 0439-433, using the
+Australia Telescope Compact Array (ATCA). The spectrum shows a weak absorption
+feature --- at the $3.3 \sigma$ level --- which yields a lower limit of 730 K
+on the spin temperature of the system. No HI emission was detected: the
+$3\sigma$ upper limit on the HI mass of the absorber is $2.25 \times 10^9
+M_{\odot}$, for a velocity spread of $\sim 70$ km s$^{-1}$. The low HI mass and
+the high spin temperature seem to rule out the possibility that the absorber is
+a large gas-rich spiral galaxy.",0012079v1
+2000-12-05,Lost and Found: The Damped Lyman Alpha Absorbers in the QSO OI 363,"The galaxy giving rise to the damped Ly$\alpha$ absorbing system in the QSO
+OI 363 with z=0.221 has been found. A galaxy which is probably associated with
+the second DLA in this same QSO at z=0.0912 has also been found. Neither galaxy
+is very luminous, and neither galaxy shows signs of extensive current star
+formation, a massive disk or lots of gas. The impact parameters for each of the
+two galaxies with respect to the QSO are reasonable. If most DLA absorbers
+arise in such low luminosity galaxies, it will be difficult to pick out the
+correct galaxy giving rise to DLA systems at high redshift within the large
+projected areal density on the sky of faint galaxies around distant QSOs.",0012109v1
+2001-01-05,Constraints from the damping tail,"The detection of anisotropy in the cosmic microwave background on arcminute
+scales by the Cosmic Background Imager (CBI) provides us with our first
+measurement of the damping tail and closes one chapter in the CMB story. We now
+have experimental verification for all of the features in the temperature
+anisotropy spectrum predicted theoretically two decades ago. The CBI result
+allows us to constrain both parameterized models based on the inflationary cold
+dark matter (CDM) paradigm and to examine model independent constraints on the
+matter content, the distance to last scattering and the thickness of the last
+scattering surface. By providing a lower limit on the duration of recombination
+it implies a lower limit on the polarization of the sub-degree scale anisotropy
+which is close to current experimental upper limits.",0101086v2
+2001-01-10,Magnetized gravitational waves,"We investigate the influence of cosmic magnetic fields on gravitational wave
+perturbations, and find exact solutions on large scales. We show that a
+large-scale magnetic field can generate large-scale non-decaying gravitational
+waves. In the general case where gravitational waves are generated by other
+mechanisms, a large-scale magnetic field introduces a new decaying tensor mode
+and modifies the non-decaying mode. The direct effect of the magnetic field is
+to damp the gravitational waves, while an indirect magneto-curvature effect can
+either damp or boost the waves. A magnetic field also leads to a breaking of
+statistical isotropy, and the magnetic imprint on the tensor spectrum in
+principle provides a means of detecting a primordial field.",0101151v3
+2001-01-15,Damping time and stability of density fermion perturbations in the expanding universe,"The classic problem of the growth of density perturbations in an expanding
+Newtonian universe is revisited following the work of Bisnovatyi-Kogan and
+Zel'dovich. We propose a more general analytical approach: a system of free
+particles satisfying semi-degenerate Fermi-Dirac statistics on the background
+of an exact expanding solution is examined in the linear approximation. This
+differs from the corresponding work of Bisnovatyi-Kogan and Zel'dovich where
+classical particles fulfilling Maxwell-Boltzmann statistics were considered.
+The solutions of the Boltzmann equation are obtained by the method of
+characteristics. An expression for the damping time of a decaying solution is
+discussed and a zone in which free streaming is hampered is found,
+corresponding to wavelengths less than the Jeans one. In the evolution of the
+system, due to the decrease of the Jeans length, those perturbations may lead
+to gravitational collapse. At variance with current opinions, we deduce that
+perturbations with lambda >=lambda_(J Max)/1.48 are able to generate structures
+and the lower limit for substructures mass is M = M_(J max)/(1.48)^3 ~ M_(J
+max)/3, where M_(J max) is the maximum value of the Jeans mass.",0101222v1
+2001-02-09,A new deuterium abundance measurement from a damped Ly-alpha system at z_abs = 3.025,"We present the first D/H measurement in a damped Ly-alpha system at z_abs =
+3.025 towards QSO 0347-3819 obtained from the UVES-VLT spectra. The DLA
+absorber has a metallicity of [Zn/H] = -1.25 and a relatively simple velocity
+structure, with two dominating components detected in several metal lines. The
+hydrogen Lyman series can be followed down to Ly12 thanks to the high UV-Blue
+efficiency of UVES. The best fit of the Lyman series lines, and in particular
+of Ly5, Ly8, Ly10 and Ly12, relatively free of local contamination, is obtained
+when the DI absorption is included in the two main components. The measured
+deuterium column density yields D/H = (2.24+/-0.67) 10^{-5} close to other low
+D/H values from Lyman limit systems. The corresponding values for the baryon to
+photon ratio and the baryon density derived from D/H are eta = 6 10^{-10} and
+Omega_b h^2 = 0.023 respectively.",0102162v1
+2001-04-24,21-cm H I emission from the Damped Lyman-alpha absorber SBS 1543+593,"We detect 21-cm emission from the Low Surface Brightness (LSB) galaxy SBS
+1543+593, which gives rise to a Damped Lyman-alpha (DLA) absorption line in the
+spectrum of the background QSO HS 1543+5921 (z=0.807). We obtain an accurate
+measure of the velocity of the H I gas in the LSB galaxy, v=2868 km/s, and
+derive a mass of 1.3e9 solar masses. We compare this value with limits obtained
+towards two other z~0.1 DLA systems, and show that SBS 1543+593 would not have
+been detected. Hence LSB galaxies similar to SBS 1543+593 can be responsible
+for DLA systems at even modest redshifts without being detectable from their
+21-cm emission.",0104396v1
+2001-05-23,Mapping the Dark Matter through the CMB Damping Tail,"The lensing of CMB photons by intervening large-scale structure leaves a
+characteristic imprint on its arcminute-scale anisotropy that can be used to
+map the dark matter distribution in projection on degree scales or ~100 Mpc/h
+comoving. We introduce a new algorithm for mass reconstruction which optimally
+utilizes information from the weak lensing of CMB anisotropies in the damping
+tail. It can ultimately map individual degree scale mass structures with high
+signal-to-noise. To achieve this limit an experiment must produce a high
+signal-to-noise, foreground-free CMB map of arcminute scale resolution,
+specifically with a FWHM beam of < 5' and a noise level of < 15 (10^-6-arcmin)
+or 41 (uK-arcmin).",0105424v2
+2001-06-30,Chandra Detection of X-ray Absorption Associated with a Damped Lyman Alpha System,"We have observed three quasars, PKS 1127-145, Q 1331+171 and Q0054+144, with
+the ACIS-S aboard the Chandra X-ray Observatory, in order to measure soft X-ray
+absorption associated with intervening 21-cm and damped Ly$\alpha$ absorbers.
+For PKS 1127-145, we detect absorption which, if associated with an intervening
+z_{abs}=0.312 absorber, implies a metallicity of 23% solar. If the absorption
+is not at z_{abs}=0.312, then the metallicity is still constrained to be less
+than 23% solar. The advantage of the X-ray measurement is that the derived
+metallicity is insensitive to ionization, inclusion of an atom in a molecule,
+or depletion onto grains. The X-ray absorption is mostly due to oxygen, and is
+consistent with the oxygen abundance of 30% solar derived from optical nebular
+emission lines in a foreground galaxy at the redshift of the absorber.
+  For Q1331+171 and Q 0054+144, only upper limits were obtained, although the
+exposure times were intentionally short, since for these two objects we were
+interested primarily in measuring flux levels to plan for future observations.
+The imaging results are presented in a companion paper.",0107003v1
+2001-08-08,The Evolution of Neutral Gas in the Universe as Traced by Damped Lyman Alpha Systems,"We discuss our recent results on the statistical properties of damped Lyman
+alpha systems (DLAs) at low redshift (z<1.65) (Rao & Turnshek 2000). Contrary
+to expectations, we found that the cosmological neutral gas mass density as
+traced by DLAs, $\Omega_{DLA}$, does not evolve from redshifts $z \approx 4$ to
+$z \approx 0.5$ and that extrapolation to z=0 results in a value that is a
+factor of ~6.5 times higher than what is derived from galaxies at the current
+epoch using HI 21 cm emission measurements. We review the current status of HI
+measurements at low redshift and at the current epoch, and discuss possible
+causes of this discrepancy.",0108141v1
+2001-08-08,Properties of Low-Redshift Damped Lyman Alpha Galaxies,"Images of five QSO fields containing six damped Lyman alpha (DLA) systems at
+redshifts 0.09<z<0.53 are presented. Identifications for the DLA galaxies
+giving rise to the DLA systems are made. The observed and modeled
+characteristics of the DLA galaxies are discussed. The DLA galaxies have impact
+parameters ranging from < 4 kpc to \approx 34 kpc and luminosities in the range
+\approx 0.03L* to \approx 1.3L*. Their morphologies include amorphous low
+surface brightness systems, a probable dwarf spiral, and luminous spirals.",0108146v1
+2001-08-29,The impact of dust and ionization effects on abundance measurements of Damped Ly alpha systems,"Studies of elemental abundances are a fundamental tool for unveiling the
+nature of the high-redshift (proto-)galaxies associated to Damped Ly alpha
+systems (DLAs). The present contribution analyses the impact of dust and
+ionization effects on abundance measurements in DLAs. The behaviour of the
+alpha/Fe abundance ratio corrected for such effects is used to derive
+information on the chemical history and nature of DLA galaxies. The alpha/Fe
+data indicate that DLAs at z~2.5 do not represent a homogeneous class of
+objects. On average, DLAs show non-enhanced alpha/Fe ratios at low metallicity,
+suggesting an origin in galaxies with low or intermittent star formation rates.",0108466v2
+2001-08-30,Reconciling Damped Ly-alpha Statistics and 21cm Studies at z=0,"Blind 21cm surveys in the local universe have shown that the local HI mass
+density, Omega_HI, is dominated by luminous, high surface brightness, spiral
+galaxies. On the other hand, surveys for host galaxies of damped Ly-alpha
+systems have not always been successful in finding bright spiral galaxies. From
+an analysis of 21cm aperture synthesis maps of nearby galaxies we show that
+this apparent contradiction can be resolved by realizing that the HI mass
+density is dominated by L* galaxies, but the HI cross section near the DLA
+threshold is more evenly distributed over galaxies with a large range in
+luminosity, gas mass, and surface brightness. The distributions of column
+densities and impact parameters of optically identified and non-identified DLA
+host galaxies in the literature and the HI maps are qualitatively in agreement.
+Due to poor number statistics of low redshift DLA systems, there is no firm
+indication that the redshift number count of low redshift DLA systems is
+inconsistent with that calculated from the nearby galaxy population.",0108498v1
+2001-09-03,GRB 000301C: a possible short/intermediate duration burst connected to a DLA system,"We discuss two main aspects of the GRB 000301C afterglow (Fynbo et al. 2000,
+Jensen et al. 2000); its short duration and its possible connection with a
+Damped Ly-alpha Absorber (DLA). GRB 000301C falls in the short class of bursts,
+though it is consistent with belonging to the proposed intermediate class or
+the extreme short end of the distribution of long-duration GRBs. Based on two
+VLT spectra we estimate the HI column density to be Log(N(HI))=21.2+/-0.5. This
+is the first direct indication of a connection between GRB host galaxies and
+Damped Ly-alpha Absorbers.",0109020v1
+2001-10-16,The UCSD HIRES/KeckI Damped Lya Abundance Database: I. The Data,"We present new chemical abundance measurements of 16 damped Lya systems at
+z>1.5 and update our previous abundance analyses. The entire database presented
+here was derived from HIRES observations on the Keck I telescope, reduced with
+the same software package, and analysed with identical techniques. Altogether,
+we present a large, homogeneous database of chemical abundance measurements for
+protogalaxies in the early universe, ideal for studying a number of important
+aspects of galaxy formation. In addition, we have established an online
+directory for this database and will continuously update the results.",0110350v1
+2001-10-16,A simple analytical model for the abundance of damped Ly-α absorbers,"A simple analytical model for estimating the fraction (\Omega_{gas}) of
+matter in gaseous form within the collapsed dark matter (DM) haloes is
+presented. The model is developed using (i) the Press-Schechter formalism to
+estimate the fraction of baryons in DM haloes, and (ii) the observational
+estimates of the star formation rate at different redshifts. The prediction for
+\Omega_{gas} from the model is in broad agreement with the observed abundance
+of the damped Ly-\alpha systems. Furthermore, it can be used for estimating the
+circular velocities of the collapsed haloes at different redshifts, which could
+be compared with future observations.",0110359v2
+2001-10-16,Unusual Metal Abundances in a Pair of Damped Lyman Alpha Systems at z~2,"We present high resolution spectroscopic observations of two neighbouring
+damped Lya systems (DLAs) along the same line of sight towards B2314-409. Due
+to their separation (v ~ 2000 km/s) and the high spectral resolution of the
+data, it is possible to fit not only the weak metal transitions, but also the
+separate HI absorption profiles. This has permitted, for the first time, a
+detailed study of metal abundances in two neighbouring galaxy-scale absorbers.
+The two DLAs have z_abs = 1.8573 and 1.8745 and have column densities log N(HI)
+= 20.9+/-0.1 and 20.1+/-0.2 respectively. We have determined abundances for a
+range of chemical elements, and find that BOTH absorbers towards B2314-409 have
+low alpha/Fe-peak abundances compared with other known DLAs. This indicates
+that not only has the recent star formation history of these absorbers been
+relatively passive, but that the group environment, or some other external
+factor, may have influenced this.",0110391v2
+2001-12-18,NICMOS Snapshot Survey of Damped Lyman Alpha Quasars,"We image 19 quasars with 22 damped Lyman alpha (DLA) systems using the F160W
+filter and the Near-Infrared Camera and Multiobject Spectrograph aboard the
+Hubble Space Telescope, in both direct and coronagraphic modes. We reach 5
+sigma detection limits of ~H=22 in the majority of our images. We compare our
+observations to the observed Lyman-break population of high-redshift galaxies,
+as well as Bruzual & Charlot evolutionary models of present-day galaxies
+redshifted to the distances of the absorption systems. We predict H magnitudes
+for our DLAs, assuming they are producing stars like an L* Lyman-break galaxy
+(LBG) at their redshift. Comparing these predictions to our sensitivity, we
+find that we should be able to detect a galaxy around 0.5-1.0 L* (LBG) for most
+of our observations. We find only one new possible candidate, that near
+LBQS0010-0012. This scarcity of candidates leads us to the conclusion that most
+DLA systems are not drawn from a normal LBG luminosity function nor a local
+galaxy luminosity function placed at these high redshifts.",0112416v1
+2002-02-19,Saturation of the R-mode Instability,"Rossby waves (r-modes) in rapidly rotating neutron stars are unstable because
+of the emission of gravitational radiation. We study saturation of this
+instability by nonlinear transfer of energy to stellar ""inertial"" oscillation
+modes. We present detailed calculations of stellar inertial modes in the WKB
+limit, their linear damping by bulk and shear viscosity, and the nonlinear
+coupling forces among these modes. The saturation amplitude is derived in the
+extreme limits of strong or weak driving by radiation reaction, as compared to
+the damping rate of low order inertial modes. We find the saturation energy is
+{\it extremely small}, at least four orders of magnitude smaller than that
+found by previous investigators. We discuss the consequences of this result for
+spin evolution of young neutron stars, and neutron stars being spun up by
+accretion in Low Mass X-ray Binaries.We also discuss the detection of these
+gravitational waves by LIGO.",0202345v2
+2002-04-05,HI 21cm imaging of a nearby Damped Lyman-alpha system,"We present Giant Metrewave Radio Telescope (GMRT) HI 21cm emission images of
+the z=0.009 damped Lyman-alpha (DLA) absorber towards the QSO HS 1543+5921. The
+DLA has been earlier identified as a low surface brightness galaxy SBS 1543+593
+at an impact parameter of ~ 400 pc to the QSO line of sight. The extremely low
+redshift of the absorber allows us to make spatially resolved images of the
+21cm emission; besides the HI mass, this also enables us to determine the
+velocity field of the galaxy and, hence, to estimate its dynamical mass.
+  We obtain a total HI mass of ~ 1.4x10^9 Msun, considerably smaller than the
+value of M*(HI) determined from blind 21cm emission surveys. This continues the
+trend of low HI mass in all low redshift DLAs for which HI emission
+observations have been attempted. We also find that the QSO lies behind a
+region of low local HI column density in the foreground galaxy. This is
+interesting in view of suggestions that DLA samples are biased against high HI
+column density systems. The dynamical mass of the galaxy is found to be Mdyn ~
+5x10^9 Msun.",0204094v1
+2002-07-15,On the Structure of the Iron K-Edge,"It is shown that the commonly held view of a sharp Fe K edge must be modified
+if the decay pathways of the series of resonances converging to the K
+thresholds are adequately taken into account. These resonances display damped
+Lorentzian profiles of nearly constant widths that are smeared to impose
+continuity across the threshold. By modeling the effects of K damping on
+opacities, it is found that the broadening of the K edge grows with the
+ionization level of the plasma and that the appearance at high ionization of a
+localized absorption feature at 7.2 keV is identified as the K-beta unresolved
+transition array.",0207324v2
+2002-08-26,"Damped Lyman alpha systems and disk galaxies: number density, column density distribution and gas density","We present a comparison between the observed properties of damped Lyman alpha
+systems (DLAs) and the predictions of simple models for the evolution of
+present day disk galaxies, including both low and high surface brightness
+galaxies. We focus in particular on the number density, column density
+distribution and gas density of DLAs, which have now been measured in
+relatively large samples of absorbers. From the comparison we estimate the
+contribution of present day disk galaxies to the population of DLAs, and how it
+varies with redshift. Based on the differences between the models and the
+observations, we also speculate on the nature of the fraction of DLAs which
+apparently do not arise in disk galaxies.",0208457v1
+2002-09-10,A search for molecules in damped Lyman-alpha absorbers occulting millimetre-loud quasars,"We have used the SEST 15-metre and Onsala 20-metre telescopes to perform deep
+(r.m.s. >~ 30 mJy) integrations of various molecular rotational transitions
+towards damped Lyman-alpha absorption systems (DLAs) known to occult
+millimetre-loud quasars. We have observed 6 new systems and improved the
+existing limits for 11 transitions. These limits may be approaching the
+sensitivities required to detect new systems and we present a small number of
+candidate systems which we believe warrant further observation.",0209175v1
+2002-11-13,Strong Absorption-line Systems at Low Redshift: MgII and Damped Lyman Alpha,"We detail a powerful indirect method for the study of damped Lyman alpha
+systems (DLAs) at low redshift. We increase the probability of finding a
+low-redshift DLA to nearly 50% by targeting QSOs that are known to have strong
+low-redshift MgII and FeII absorption lines in their spectra. We are using
+Sloan Digital Sky Survey QSO spectra complemented by a survey we are conducting
+at the MMT to study the metal-line systems. The Hubble Space Telescope is being
+used to confirm low-redshift DLAs. In addition, we are imaging low-redshift DLA
+galaxies with several ground-based telescopes to directly study their
+environments.",0211295v1
+2002-11-22,On the Origin of Nitrogen in Damped Ly-alpha Systems,"Recent measurements of nitrogen and alpha elements in over 20 damped Ly-alpha
+systems (DLA) are compared with similar measurements for numerous emission line
+objects and stars. It is found that the DLA distribution in the N/alpha-alpha/H
+plane is bimodal, where most sample DLAs fall along the N/alpha plateau defined
+at low Z by dwarf irregulars, while a small group possesses N/alpha values
+roughly 0.7 dex less than those on the plateau at similar alpha/H values. We
+demonstrate with chemical evolution models that a top-heavy or truncated IMF
+can account for the low N in this second group.",0211512v1
+2002-12-16,Fragmentation and Collapse of Turbulent Molecular Clouds,"We performed simulations of self-gravitating hydrodynamic turbulence to model
+the formation of filaments, clumps and cores in molecular clouds. We find that
+when the mass on the initial computational grid is comparable to the Jeans
+mass, turbulent pressure is able to prevent gravitational collapse. When the
+turbulence has damped away sufficiently, gravitational collapse can occur, and
+the resulting structure closely resembles the pre-singularity collapse of an
+isothermal sphere of Penston (1969). If several Jeans masses are initially
+placed on the grid, turbulence may not be sufficient to prevent collapse before
+turbulence can be significantly damped. In this case, the cores have density
+structures which are considerably shallower than expected for an isothermal
+gas, and resemble the solutions for a logatropic equation of state.",0212359v1
+2003-02-20,One-Armed Spiral Instability in Differentially Rotating Stars,"We investigate the dynamical instability of the one-armed spiral m=1 mode in
+differentially rotating stars by means of 3+1 hydrodynamical simulations in
+Newtonian gravitation. We find that both a soft equation of state and a high
+degree of differential rotation in the equilibrium star are necessary to excite
+a dynamical m=1 mode as the dominant instability at small values of the ratio
+of rotational kinetic to potential energy, T/|W|. We find that this spiral mode
+propagates outward from its point of origin near the maximum density at the
+center to the surface over several central orbital periods. An unstable m=1
+mode triggers a secondary m=2 bar mode of smaller amplitude, and the bar mode
+can excite gravitational waves. As the spiral mode propagates to the surface it
+weakens, simultaneously damping the emitted gravitational wave signal. This
+behavior is in contrast to waves triggered by a dynamical m=2 bar instability,
+which persist for many rotation periods and decay only after a
+radiation-reaction damping timescale.",0302436v2
+2003-03-21,Molecular Hydrogen in Damped Ly-alpha Systems: Spatial Distribution,"To interpret H_2 quasar absorption line observations in Damped Ly-alpha
+clouds (DLAs), we model the H_2 spatial distribution within a DLA. Based on
+numerical simulations of disk structures with parameters similar to those
+derived for such absorbers, we calculate the H_2 distribution as a function of
+ultraviolet background (UVB) intensity and dust-to-gas ratio. For typical
+values of these two quantities we find that the area in which the H_2 fraction
+exceeds 10^{-6} (typical observational detection limit) only covers $\la 10$%
+of the disk surface, i.e. H_2 has a very inhomogeneous, clumpy distribution
+even at these low abundance levels. This explains the relative paucity of H_2
+detections in DLAs. We also show the dependence of the covering fraction of H_2
+on dust-to-gas ratio and UVB intensity and we comment on the physics governing
+the H_2 chemical network at high redshift.",0303495v1
+2003-05-02,The Critical Rotation of Strange Stars and Rapidly Rotating Pulsars,"We utilize the bulk viscosity of interacting strange quark matter to
+reevaluate the damping time scale. The presence of medium effect of bulk
+viscosity leads to a stronger damping of r-modes, which can be over an order of
+magnitude for realistic parameters. We find that the r-mode instability window
+is narrowed due to the medium effect, and hence when a pulsar reaches the
+instability window it will only slow down by gravitational wave emission to a
+period of 1.78msec instead of 2.5msec given by early estimate. As a theoretical
+upper rotation limit of pulsars, the period of 1.78msec is very close to the
+two most rapidly spinning pulsars known, with periods of about 1.6msec.",0305034v1
+2003-06-02,Chemical Evolution of Damped Lyman Alpha Systems,"By means of detailed chemical evolution models for galaxies of different
+morphological types (i.e. spirals, irregular/starburst galaxies and
+ellipticals) we study the nature of Damped Lyman-Alpha systems. Our concern is
+to infer which systems represent likely candidates for the DLA population and
+which do not. By focusing on individual systems, we can derive some constraints
+on both the nature of the associated galaxy and its age. Our results indicate
+that, owing to their high metallicities and [alpha/Fe] ratios, big spheroids
+represent unlikely DLA candidates whereas spirals (observed at different
+galactocentric distances) and irregulars are ideal sites where DLA absorptions
+can occur.",0306037v1
+2003-07-01,Clustering of galaxies at z=3 around the probable Damped Ly-alpha absorber towards QSO APM 08279+5255,"[Abridged] We present results on the clustering og Lyman break galaxies
+(LBGs) around a probable damped Ly-alpha absorption (DLA) line cloud at
+z_DLA=2.974 from deep UBVI images of the field containing the quasar APM
+08279+5255 (z=3.91). The large area covered by our images, 0.31 deg^2 or 40x40
+Mpc co-moving at z=3, and their depth (27.6 mag arcsec^{-2}), allow us to
+identify 450 LBG candidates brighter than I(AB)=24.80 at 2.75<z<3.25. LBG
+candidates were selected using photometric redshift techniques that include
+priors within a redshift slice of width Wz=0.15 centered at z_DLA.
+  Within that redshift slice, we find an enhancement of galaxies near the DLA
+using both the surface density and an estimator of the 3-D spatial
+over-density. The surface overdensity (3\times) is significant at the >95%
+significance level on scales 2.5<r<5 Mpc co-moving and imply that some DLA
+could reside in high density regions.",0307033v1
+2003-08-11,Imaging and spectroscopy of galaxies associated with two z~0.7 damped Lyman-alpha absorption systems,"We have identified galaxies near two quasars which are at the redshift of
+damped Lyman-alpha (DLA) systems in the UV spectra of the quasars. Both
+galaxies are actively forming stars. One galaxy has a luminosity close to the
+break in the local galaxy luminosity function, L*, the other is significantly
+fainter than L* and appears to be interacting with a nearby companion. Despite
+the strong selection effects favoring spectroscopic identification of the most
+luminous DLA galaxies, many of the spectroscopically-identified DLA galaxies in
+the literature are sub-L*, suggesting that the majority of the DLA population
+is probably sub-L*, in contrast to MgII absorbers at similar redshifts whose
+mean luminosity is close to L*.",0308193v1
+2003-09-03,The Thermal Stability of Mass-Loaded Flows,"We present a linear stability analysis of a flow undergoing
+conductively-driven mass-loading from embedded clouds. We find that
+mass-loading damps isobaric and isentropic perturbations, and in this regard is
+similar to the effect of thermal conduction, but is much more pronounced where
+many embedded clumps exist. The stabilizing influence of mass-loading is
+wavelength independent against isobaric (condensing) perturbations, but
+wavelength dependent against isentropic (wave-like) perturbations. We derive
+equations for the degree of mass-loading needed to stabilize such
+perturbations. We have also made 1D numerical simulations of a mass-loaded
+radiative shock and demonstrated the damping of the overstability when
+mass-loading is rapid enough.",0309086v1
+2003-09-22,Hierarchical Structure Formation and Chemical Evolution of Damped Ly alpha Systems,"We present a model for chemical evolution of damped Ly alpha systems
+considering production of metals by SNe II and infall associated with
+hierarchical structure formation. The growth of metallicity in these systems is
+a reflection of the competition between astration and infall. The apparent late
+turn-on of these systems is due to the late cut-off of infall. The wide range
+in [Fe/H] at a given redshift is explained by the range of the times for onset
+of star formation and the range of the times for infall cessation in different
+systems. The observed lower bound of [Fe/H] = -3 follows from the very rapid
+initial rise of [Fe/H] subsequent to onset of star formation. To reach [Fe/H] =
+-3 from a metal-free initial state requires only about 30 Myr so that the
+probability of observing lower [Fe/H] values is very small.",0309600v1
+2003-09-29,A common trend in the chemical evolution of Local Group dwarf spheroidals and Damped Ly-alpha systems,"We compare chemical abundances of Local Group dwarf spheroidals, obtained
+from recent UVES/VLT observations, and of high redshift Damped Lyman alpha
+systems (DLAs), corrected for dust effects. We focus, in particular, on the
+abundance ratio between alpha-capture elements and iron, alpha/Fe, a well known
+indicator of chemical evolution. Comparison of the data in the plane alpha/Fe
+versus Fe/H shows a remarkable similarity between the dwarf spheroidals and the
+DLAs, suggestive of a common trend in their chemical evolution. At any given
+metallicity these two distinct types of astronomical targets show alpha/Fe
+ratios systematically lower than those of Milky Way stars. In terms of chemical
+evolution models, this suggests that, on average, dSph galaxies and DLA systems
+are characterized by lower, or more episodic, star formation rates than the
+Milky Way.",0309765v1
+2003-10-15,H_2-bearing damped Lyman-alpha systems as tracers of cosmological chemical evolution,"The chemical abundances in damped Lyman-alpha systems (DLAs) show more than 2
+orders of magnitude variation at a given epoch, possibly because DLAs arise in
+a wide variety of host galaxies. This could significantly bias estimates of
+chemical evolution. We explore the possibility that DLAs in which H_2
+absorption is detected may trace cosmological chemical evolution more reliably
+since they may comprise a narrower set of physical conditions. The 9 known H_2
+absorption systems support this hypothesis: metallicity exhibits a faster, more
+well-defined evolution with redshift than in the general DLA population. The
+dust-depletion factor and, particularly, H_2 molecular fraction also show rapid
+increases with decreasing redshift. We comment on possible observational
+selection effects which may bias this evolution. Larger samples of H_2-bearing
+DLAs are clearly required and may constrain evolution of the UV background and
+DLA galaxy host type with redshift.",0310409v2
+2004-01-21,Constraints on Early Nucleosynthesis from the Abundance Pattern of a Damped Ly-alpha System at z = 2.626,"We have investigated chemical evolution in the young universe by analysing
+the detailed chemical enrichment pattern of a metal-rich galaxy at high
+redshift. The recent detection of over 20 elements in the gas-phase of a damped
+Lyman-alpha absorber (DLA) at z = 2.626 represents an exciting new avenue for
+exploring early nucleosynthesis. Given a strict upper age of ~2.5 Gyr and a
+gas-phase metallicity about one third solar, we have shown the DLA abundance
+pattern to be consistent with the predictions of a chemical evolution model in
+which the interstellar enrichment is dominated by massive stars with a small
+contribution from Type Ia supernovae. Discrepancies between the empirical data
+and the models are used to highlight outstanding issues in nucleosynthesis
+theory, including a tendency for Type II supernovae models to overestimate the
+magnitude of the ""odd-even"" effect at subsolar metallicities. Our results
+suggest a possible need for supplemental sources of magnesium and zinc, beyond
+that provided by massive stars.",0401413v1
+2004-03-23,The clustering of galaxies around three damped Ly-alpha absorbers at Redshift Three,"[Abridged] We present out results on the cross-correlation of Lyman break
+galaxies (LBGs) around three damped \Ly absorbers (DLAs) at redshift three from
+deep multi-band MOSAIC images obtained at the KPNO 4m. The large area of the
+MOSAIC images, 0.31 $\deg^2$ allows us to probe the clustering of LBGs on
+scales up to 20 Mpc co-moving to test whether DLA halos are more or less
+massive than LBG halos. . We present our survey that covers a total of 1
+deg$^2$ and contains $\sim$3,000 LBGs with photometric redshifts between 2.8
+and 3.5.
+  Within a redshift slice of width $W_z=0.15$, we find that the DLA-LBG
+cross-correlation is $1.6\pm 1.3$ times the LBG-LBG autocorrelation. This
+corresponds to a correlation length of $r_o=5\pm4.5h^{-1}$ (co-moving). The
+cross-correlation is most significant on scales 5-10 Mpc, and is significantly
+greater than zero at the $>95$% level from Monte Carlo simulations.",0403544v2
+2004-03-31,Cold Neutral Gas in a z=4.2 Damped Lyman-alpha System: The Fuel for Star Formation,"We discuss interstellar temperature determinations using the excitation
+equilibrium of the ^2P levels of Si II and C II. We show how observations of
+the ^2P_3/2 fine structure levels of Si II and C II (which have significantly
+different excitation energies, corresponding to ~413 and 92 K, respectively)
+can be used to limit gas kinetic temperatures. We apply this method to the
+z=4.224 damped Lyman-alpha system toward the quasar PSS1443+27. The lack of
+significant absorption out of the SiII ^2P_3/2 level and the presence of very
+strong C II ^2P_3/2 provides an upper limit to the temperature of the C
+II*-bearing gas in this system. Assuming a solar Si/C ratio, the observations
+imply a 2-sigma limit T<954 K for this absorber; a super-solar Si/C ratio gives
+stricter limits, T<524 K. The observations suggest the presence of a cold
+neutral medium; such cold gas may serve as the fuel for star formation in this
+young galaxy.",0404005v2
+2004-04-27,Molecular fraction limits in damped Lyman-alpha absorption systems,"We have used the Green Bank Telescope (GBT) and Berkeley-Illinois-Maryland
+Association (BIMA) array to search for redshifted millimetre absorption in a
+sample of damped Lyman-alpha absorption systems (DLAs). This brings the number
+of published systems searched from 18 to 30. In 17 cases we reach $3\sigma$
+limits of $\tau\leq0.1$, which is a significant improvement over the previous
+searches and more than sufficient to detect the 4 known redshifted millimetre
+absorbers ($\tau\gapp1$). While the CO rotational (millimetre) column density
+limits obtained are weaker than the electronic (optical) limits, they may
+provide useful limits below the atmospheric cut-off for the Lyman and Werner
+\MOLH-bands in the UV ($z_{\rm abs}\lapp1.8$). Using a model for the DLA
+metallicity evolution combined with assumed HCO$^+$/\MOLH ~and CO/\MOLH
+\~conversion ratios, we use the molecular column density limits to calculate
+plausible \MOLH ~molecular fraction limits. Finally, we use these results to
+discuss the feasibility of detecting rotational CO transitions in DLAs with the
+next generation of large radio telescopes.",0404516v1
+2004-08-07,Metals and Dust in Intermediate-redshift Damped Ly-alpha Galaxies,"We report spectroscopic observations with the Multiple Mirror Telescope for
+11 damped Lyman-alpha absorbers (DLAs) or strong DLA candidates at 0.1 < z <
+1.5, including several absorbers discovered in the Sloan Digital Sky Survey. In
+particular, we have measured absorption lines of Zn II, Cr II, Ni II, Fe II, Mn
+II, Ti II, Ca II, and Si II. These measurements have doubled the sample of Zn
+and Cr measurements at z < 1. The average relative abundance patterns in these
+objects are very similar to those found for high-redshift DLAs reported in the
+literature. Our observations suggest that the dust content, as determined by
+[Cr/Zn], does not show much change with redshift. We also examine the sample
+for correlation of [Cr/Zn] with estimates of the quasar reddening. Our data
+suggest that the global mean metallicity of DLAs, as measured by the gas phase
+abundance of Zn, at best shows a weak evolution with redshift over the range
+0.4 < z <3.9.",0408139v1
+2004-09-22,On Detecting the X-ray Silhouette of a Damped Lyman alpha System,"We explore the possibility of resolving an image of a damped Lyman alpha
+(DLA) system in absorption against an extended, diffuse background X-ray
+source. Typical columns of neutral hydrogen in DLAs are high enough to block
+out up to ~30% of the soft X-ray flux at an observed photon energy of 0.5 keV,
+and we find that ~ 1% of the area of extended X-ray sources at z > 1 have their
+0.5 keV flux reduced by at least 20%. We discuss the observability of such
+absorption and find that < 2 arcsecond resolution, and > 300 photons per
+angular resolution element are required in the 0.3-8 keV band for its
+detection, and in order to distinguish it from intrinsic surface brightness
+fluctuations. For the surface brightness of the currently known high-redshift
+extended X-ray sources, this requires an integration time of a few Msec on
+Chandra. The detection will be within the reach of a routine observation with a
+next generation X-ray telescope such as XEUS or Generation X.",0409516v2
+2004-10-11,Is the solar corona nonmodally self-heated?,"Recently it was pointed out that nonmodally (transiently and/or
+adiabatically) pre-amplified waves in shear flows, undergoing subsequent
+viscous damping, can ultimately heat the ambient flow. The key ingredient of
+this process is the ability of waves to grow, by extracting energy from the
+spatially inhomogeneous mean flow. In this paper we examine this mechanism in
+the context of the solar coronal plasma flows. ""Self-heating"" (SH) processes
+are examined when both viscous damping and magnetic resistivity are at work. We
+show that if the plasma viscosity is in the favorable range of values the
+asymptotic SH rate in these flows can be quite substantial.",0410279v1
+2004-10-23,Extended Neutral Gas Around z ~ 0.5 Galaxies: Properties of Damped Lya Absorbing Galaxies,"I review current results from searching for galaxies giving rise to damped
+Lya absorbers (DLAs) at z<1. Using 14 confirmed DLA galaxies, I further show
+that intermediate-redshift galaxies possess large HI envelope out to 24-30
+h^{-1} kpc radius. The photometric and spectral properties of these galaxies
+confirm that DLA galaxies are drawn from the typical field population, and not
+from a separate population of low surface brightness or dwarf galaxies.
+Comparisons of the ISM abundances of the DLA galaxies and the metallicities of
+the absorbers at large galactic radii suggest that some DLAs originate in the
+relatively unevolved outskirts of galactic disks.",0410558v1
+2004-11-25,Survey for Galaxies Associated with z~3 Damped Lyman alpha Systems I: Spectroscopic Calibration of u'BVRI Photometric Selection,"We present a survey for z~3 Lyman break galaxies (LBGs) associated with
+damped Lyman alpha systems (DLAs) with the primary purpose of determining the
+DLA-LBG cross-correlation. This paper describes the acquisition and analysis of
+imaging and spectroscopic data of 9 quasar fields having 11 known z~3 DLAs
+covering an area of 465 arcmin^2. Using deep u'BVRI images, 796 LBG candidates
+to an apparent R_AB magnitude of 25.5 were photometrically selected from 17,343
+sources detected in the field. Spectroscopic observations of 529 LBG candidates
+using Keck LRIS yielded 339 redshifts. We have conservatively identified 211
+z>2 objects with <z>=3.02+/-0.32. We discuss our method of z~3 LBG
+identification and present a model of the u'BVRI photometric selection
+function. We use the 339 spectra to evaluate our u'BVRI z~3 Lyman break
+photometric selection technique.",0411681v1
+2005-01-06,Observations of Solar Flare Doppler Shift Oscillations with the Bragg Crystal Spectrometer on Yohkoh,"Oscillations in solar coronal loops appear to be a common phenomenon.
+Transverse and longitudinal oscillations have been observed with both the
+Transition Region and Coronal Explorer and Extreme Ultraviolet Imaging
+Telescope imaging experiments. Damped Doppler shift oscillations have been
+observed in emission lines from ions formed at flare temperatures with the
+Solar Ultraviolet Measurements of Emitted Radiation Spectrometer. These
+observations provide valuable diagnostic information on coronal conditions and
+may help refine our understanding of coronal heating mechanisms. I have
+initiated a study of the time dependence of Doppler shifts measured during
+flares with the Bragg Crystal Spectrometer (BCS) on Yohkoh. This Letter reports
+the detection of oscillatory behavior in Doppler shifts measured as a function
+of time in the emission lines of S XV and Ca XIX. For some flares, both lines
+exhibit damped Doppler shift oscillations with amplitudes of a few km/s and
+periods and decay times of a few minutes. The observations appear to be
+consistent with transverse oscillations. Because the BCS observed continuously
+for almost an entire solar cycle, it provides numerous flare data sets, which
+should permit an excellent characterization of the average properties of the
+oscillations.",0501093v1
+2005-03-09,Abundances in Damped Ly-alpha Galaxies,"Damped Ly_alpha galaxies provide a sample of young galaxies where chemical
+abundances can be derived throughout the whole universe with an accuracy
+comparable to that for the local universe. Despite a large spread in redshift,
+HI column density and metallicity, DLA galaxies show a remarkable uniformity in
+the elemental ratios rather suggestive of similar chemical evolution if not of
+an unique population. These galaxies are characterized by a moderate, if any,
+enhancement of alpha-elements over Fe-peak elemental abundance with [S/Zn]
+about 0 and [O/Zn] about 0.2, rather similarly to the dwarfs galaxies in the
+Local Group. Nitrogen shows a peculiar behaviour with a bimodal distribution
+and possibly two plateaux. In particular, the plateau at low N abundances
+([N/H] < -3), is not observed in other atrophysical sites and might be evidence
+for primary N production by massive stars.",0503214v1
+2005-03-10,Pulsar: repeatable Lagrangian singularity,"In general, the interior of radially symmetric self-gravitating sphere is
+considered in terms of hydrostatic equilibrium (HSE). This approach implies the
+possibility of the static being of a body. Such a static state is assumed to be
+the result of asymptotic damping of the process of formation. It is shown here
+that the damping of this process is impossible: if a sphere vibrates radially,
+then compressional wave is singular at the centre; dynamical singularity has no
+intermediate stages of the fading; the HSE-state is unachievable.
+Self-gravitating sphere perpetually vibrates in essentially singular way, it
+contains dynamical central region -- pulsatile Lagrangian cavity. Theoretical
+properties of this cavity indicate that this is a pulsar. A pulsar is common
+structural feature for every self-gravitating structure.",0503231v2
+2005-03-14,Quasi-Periodic Oscillations in Relativistic Tori,"Motivated by recent interesting work on p-mode oscillations in axisymmetric
+hydrodynamic black-hole tori by Rezzolla, Zanotti, and collaborators, I explore
+the robustness of these oscillations by means of two and three-dimensional
+relativistic hydrodynamic and MHD simulations. The primary purpose of this
+investigation is to determine how the amplitudes of these oscillations are
+affected by the presence of known instabilities of black-hole tori, including
+the Papaloizou-Pringle instability (PPI) and the magneto-rotational instability
+(MRI). Both instabilities drive accretion at rates above those considered in
+Rezzolla's work. The increased accretion can allow wave energy to leak out of
+the torus into the hole. Furthermore, with the MRI, the presence of turbulence,
+which is absent in the hydrodynamic simulations, can lead to turbulent damping
+(or excitation) of modes. The current numerical results are preliminary, but
+suggest that the PPI and MRI both significantly damp acoustic oscillations in
+tori.",0503305v1
+2005-03-17,The first observed stellar X-ray flare oscillation: Constraints on the flare loop length and the magnetic field,"We present the first X-ray observation of an oscillation during a stellar
+flare. The flare occurred on the active M-type dwarf AT Mic and was observed
+with XMM-Newton. The soft X-ray light curve (0.2-12 keV) is investigated with
+wavelet analysis. The flare's extended, flat peak shows clear evidence for a
+damped oscillation with a period of around 750 s, an exponential damping time
+of around 2000 s, and an initial, relative peak-to-peak amplitude of around
+15%. We suggest that the oscillation is a standing magneto-acoustic wave tied
+to the flare loop, and find that the most likely interpretation is a
+longitudinal, slow-mode wave, with a resulting loop length of (2.5 +- 0.2) e10
+cm. The local magnetic field strength is found to be (105 +- 50) G. These
+values are consistent with (oscillation-independent) flare cooling time models
+and pressure balance scaling laws. Such a flare oscillation provides an
+excellent opportunity to obtain coronal properties like the size of a flare
+loop or the local magnetic field strength for the otherwise
+spatially-unresolved star.",0503384v1
+2005-04-25,Emission-line spectroscopy of Damped Lyman Alpha Systems: The case of SBS 1543+593/HS 1543+5921,"We report HST/STIS spectroscopy and Gemini/GMOS-N imaging of the Damped Lyman
+Alpha (DLA) system toward HS 1543+5921 caused by the host star-forming galaxy
+(SFG) SBS 1543+593. The Gemini image shows new morphological details of this
+well resolved DLA galaxy. In combination with previous optical spectra, the new
+UV spectra enable us to compare for the first time, ionized and neutral
+gas-phase alpha-element abundances derived from emission- and absorption-line
+spectroscopy, in a bona fide DLA galaxy. The abundances we determine using
+emission-line diagnostics agree with those from absorption-line diagnostics. We
+present our results on a metallicity versus redshift diagram that combines
+local HII regions and SFGs with high-redshift DLAs, and discuss implications
+for the chemical evolution of galaxies.",0504556v1
+2005-04-27,Self-consistent radiative effect on relativistic electromagnetic particle acceleration,"We study the radiation damping effect on the relativistic acceleration of
+electron-positron plasmas with two-and-half-dimensional particle-in-cell (PIC)
+simulation. Particles are accelerated by Poynting flux via the diamagnetic
+relativistic pulse accelerator (DRPA), and decelerated by the self-consistently
+solved radiation damping force. With $\Omega_{ce}/\omega_{pe}\geq 10$, the
+Lorentz factor of the highest energy particles reaches gamma>100, and the
+acceleration still continues. The emitted radiation is peaked within few
+degrees from the direction of Poynting flux and strongly linearly polarized,
+which may be detectable in gamma-ray burst(GRB) observations. We also show that
+the DRPA is insensitive to the initial supporting currents.",0504612v2
+2005-07-13,UHE neutrino damping in a thermal gas of relic neutrinos,"We present a calculation of the damping of an ultra-energetic (UHE) cosmic
+neutrino travelling through the thermal gas of relic neutrinos, using the
+formalism of finite-temperature field theory. From the self-energy diagram due
+to Z exchange, we obtain the annihilation cross section for an UHE neutrino
+interacting with an antineutrino from the background. This method allows us to
+derive the full expressions for the UHE neutrino transmission probability,
+taking into account the momentum of relic neutrinos. We compare our results
+with the approximations in use in the literature. We discuss the effect of
+thermal motion on the shape of the absorption dips for different UHE neutrino
+fluxes as well as in the context of relic neutrino clustering. We find that for
+ratios of the neutrino mass to the relic background temperature $10^2$ or
+smaller, the thermal broadening of the absorption lines could significantly
+affect the determination of the neutrino mass and of the characteristics of the
+population of UHE sources.",0507333v2
+2005-07-25,Post-inflation increase of the cosmological tensor-to-scalar perturbation ratio,"We investigate the possibility that the amplitude of scalar density
+perturbations may be damped after inflation. This would imply that CMB
+anisotropies do not uniquely fix the amplitude of the perturbations generated
+during inflation and that the present tensor-to-scalar ratio might be larger
+than produced in inflation, increasing the prospects of detection of primordial
+gravitational radiation. It turns out, however, that the damping of density
+perturbations is hard to achieve.",0507573v3
+2005-09-08,Possible Detection of Lyman-alpha Fluorescence from a Damped Lyman Alpha system at Redshift z=2.8,"We have detected Lyman-alpha emission from a damped Lyman-alpha system (DLA)
+that lies near the bright quasar HS1549+1919. The DLA has the same redshift as
+HS1549+1919 and was discovered in the spectrum of a faint QSO that lies 49""
+away (380 proper kpc). The emission line's luminosity, double-peaked profile,
+and small spatial separation from the DLA suggest that it may be fluorescent
+Lyman-alpha emission from gas that is absorbing the nearby QSO's radiation. If
+this is the case, our observations show that the DLA has a size of at least
+1.5"" and that the QSO's luminosity one million years ago was similar to its
+luminosity today. A survey for similar systems within 1' of bright QSOs would
+put interesting limits on the mean quasar lifetime.",0509229v1
+2005-11-17,Measurement of the Spatial Cross-Correlation Function of Damped Lyman Alpha Systems and Lyman Break Galaxies,"We present the first spectroscopic measurement of the spatial
+cross-correlation function between damped Lyman alpha systems (DLAs) and Lyman
+break galaxies (LBGs). We obtained deep u'BVRI images of nine QSO fields with
+11 known z ~ 3 DLAs and spectroscopically confirmed 211 R < 25.5
+photometrically selected z > 2 LBGs. We find strong evidence for an overdensity
+of LBGs near DLAs versus random, the results of which are similar to that of
+LBGs near other LBGs. A maximum likelihood cross-correlation analysis found the
+best fit correlation length value of r_0 = 2.9^(+1.4)_(-1.5) h^(-1)Mpc using a
+fixed value of gamma = 1.6. The implications of the DLA-LBG clustering
+amplitude on the average dark matter halo mass of DLAs are discussed.",0511509v1
+2006-01-29,Relative abundance pattern along the profile of high redshift Damped Lyman-alpha systems,"We investigated abundance ratios along the profiles of six high-redshift
+Damped Lyman-alpha systems, three of them associated with H2 absorption, and
+derived optical depths in each velocity pixel. The variations of the pixel
+abundance ratios were found to be remarkably small and usually smaller than a
+factor of two within a profile. This result holds even when considering
+independent sub-clumps in the same system. The depletion factor is
+significantly enhanced only in those components where H2 is detected. There is
+a strong correlation between [Fe/S] and [Si/S] abundances ratios, showing that
+the abundance ratio patterns are definitely related to the presence of dust.
+The depletion pattern is usually close to the one seen in the warm halo gas of
+our Galaxy.",0601664v1
+2006-02-14,VLT/UVES constraints on the carbon isotope ratio 12C/13C at z=1.15 toward the quasar HE 0515-4414,"We analyzed the CI lines associated with the damped Ly-alpha system observed
+at zabs = 1.15 in the spectrum of HE 0515-4414 to derive the 12C/13C ratio. The
+spectrum was obtained by means of the UV-Visual Echelle Spectrograph (UVES) at
+the ESO Very Large Telescope (VLT). The obtained lower limit 12C/13C > 80
+(2sigma C.L.) shows for the first time that the abundance of 13C in the
+extragalactic intervening clouds is very low. This rules out a significant
+contribution from intermediate-mass stars to the chemical evolution of matter
+sampled by this line of sight. The estimated low amount of 13C is in agreement
+with low abundances of nitrogen observed in damped Ly-alpha systems - the
+element produced in the same nuclear cycles and from about the same stars as
+13C.",0602303v1
+2006-06-08,The detectability of HI 21-cm absorption in damped Lyman-alpha systems,"In this paper we investigate the possible reasons why HI 21-cm absorption in
+damped Lyman-alpha systems (DLAs) has only been detected at low redshift... We
+suggest that the lack of 21-cm absorption detections at high redshift arises
+from the fact that these DLAs are at similar angular diameter distances to the
+background quasars (i.e. the distance ratios are always close to unity): Above
+z~1.6 the covering factor becomes largely independent of the DLA--QSO distance,
+making the high redshift absorbers much less effective at covering the
+background continuum emission. At low redshift, small distance ratios are
+strongly favoured by the 21-cm detections, whereas large ratios are favoured by
+the non-detections. This mix of distance ratios gives the observed mix of
+detections and non-detections at z<1.6.In addition to the predominance of large
+distance ratios and non-detections at high redshift, this strongly suggests
+that the observed distribution of 21-cm absorption in DLAs is dominated by
+geometric effects.",0606180v1
+2006-07-15,Damping and excitation variations of the solar acoustic modes using LOWL observations,"We have used observations made with the helioseismic instrument LOWL
+collected over $\sim$ 6 years to carry out an independent study of the
+variations of the p-mode damping and excitation rates with solar activity. We
+observe significant variations in the mode height, mode width and mode velocity
+power over a wide range of angular degree values. Their sensitivities to solar
+activity show clear evidence of frequency dependence, the modes in the
+frequency range from 2700 and 3300 $\mu$Hz showing the largest variations and
+exhibiting a maximum change centered around 3100 $\mu$Hz. As for the mode
+energy supply rate, it is consistent, at the level of precision of the
+observations, with a zero change along the solar cycle and over the range of
+studied frequencies. Moreover, the variations with solar activity of each of
+these parameters are observed to be more or less $\ell$-independent over the
+range of studied angular degrees. Our results provide the first in-depth
+confirmation of the findings obtained from GONG measurements for intermediate
+angular degrees.",0607346v1
+2006-09-01,A line profile analysis of the pulsating red giant star epsilon Ophiuchi (G9.5III),"So far, solar-like oscillations have been studied using radial velocity
+and/or light curve variations, which reveal frequencies of the oscillation
+modes. Line-profile variations, however, are also a valuable diagnostic to
+characterise radial and non-radial oscillations, including frequencies,
+amplitudes, the spherical mode wavenumbers (l,m) and the stellar inclination
+angle. Here we present a line profile analysis of epsilon Ophiuchi, which is a
+pulsating red giant. The main differences compared to previous line profile
+analyses done for heat-driven oscillations are the small amplitudes and the
+predicted short damping and re-excitation times in red giants.
+  Two line diagnostics have been tested to see whether these are sensitive to
+the small line profile variations present in red giants. In addition, line
+profiles have been simulated with short damping and re-excitation times and are
+compared with the observations. This comparison reveals that non-radial modes
+are detected in the observed line profile variations of epsilon Ophiuchi. This
+is rather surprising, as theoretical predictions favours the occurrence of
+radial modes.",0609043v1
+2006-10-11,Determining the neutron star equation of state using the narrow-band gravitational wave detector Schenberg,"We briefly review the properties of quasi-normal modes of neutron stars and
+black holes. We analyse the consequences of a possible detection of such modes
+via the gravitational waves associated with them, especially addressing our
+study to the Brazilian spherical antenna, on which a possible detection would
+occur at 3.0-3.4 kHz. A question related to any putative gravitational wave
+detection concerns the source that produces it. We argue that, since the
+characteristic damping times for the gravitational waves of neutron stars and
+black holes are different, a detection can distinguish between them, and also
+distinguish the neutron stars oscillating modes. Moreover, since the source can
+be identified by its characteristic damping time, we are able to extract
+information about the neutron star or black hole. This information would lead,
+for example, to a strong constraint in the nuclear matter equation of state,
+namely the compression modulus should be K=220 MeV.",0610335v1
+2006-12-14,Three dimensional numerical simulations of acoustic wave field in the upper convection zone of the Sun,"Results of numerical 3D simulations of propagation of acoustic waves inside
+the Sun are presented. A linear 3D code which utilizes realistic OPAL equation
+of state was developed by authors. Modified convectively stable standard solar
+model with smoothly joined chromosphere was used as a background model. High
+order dispersion relation preserving numerical scheme was used to calculate
+spatial derivatives. The top non-reflecting boundary condition established in
+the chromosphere absorbs waves with frequencies greater than the acoustic
+cut-off frequency which pass to the chromosphere, simulating a realistic
+situation. The acoustic power spectra obtained from the wave field generated by
+sources randomly distributed below the photosphere are in good agreement with
+observations. The influence of the height of the top boundary on results of
+simulation was studied. It was shown that the energy leakage through the
+acoustic potential barrier damps all modes uniformly and does not change the
+shape of the acoustic spectrum. So the height of the top boundary can be used
+for controlling a damping rate without distortion of the acoustic spectrum. The
+developed simulations provide an important tool for testing local
+helioseismology.",0612364v1
+2006-12-15,Damp Mergers: Recent Gaseous Mergers without Significant Globular Cluster Formation?,"Here we test the idea that new globular clusters (GCs) are formed in the same
+gaseous (""wet"") mergers or interactions that give rise to the young stellar
+populations seen in the central regions of many early-type galaxies. We compare
+mean GC colors with the age of the central galaxy starburst. The red GC
+subpopulation reveals remarkably constant mean colors independent of galaxy
+age. A scenario in which the red GC subpopulation is a combination of old and
+new GCs (formed in the same event as the central galaxy starburst) can not be
+ruled out; although this would require an age-metallicity relation for the
+newly formed GCs that is steeper than the Galactic relation. However, the data
+are also well described by a scenario in which most red GCs are old, and few,
+if any, are formed in recent gaseous mergers. This is consistent with the old
+ages inferred from some spectroscopic studies of GCs in external systems. The
+event that induced the central galaxy starburst may have therefore involved
+insufficient gas mass for significant GC formation. We term such gas-poor
+events ""damp"" mergers.",0612415v1
+2006-12-21,Accretion of Terrestrial Planets from Oligarchs in a Turbulent Disk,"We have investigated the final accretion stage of terrestrial planets from
+Mars-mass protoplanets that formed through oligarchic growth in a disk
+comparable to the minimum mass solar nebula (MMSN), through N-body simulation
+including random torques exerted by disk turbulence due to
+Magneto-Rotational-Instability. For the torques, we used the semi-analytical
+formula developed by Laughlin et al.(2004). The damping of orbital
+eccentricities (in all runs) and type-I migration (in some runs) due to the
+tidal interactions with disk gas are also included. We found that the orbital
+eccentricities pumped up by the turbulent torques and associated random walks
+in semimajor axes tend to delay isolation of planets, resulting in more
+coagulation of planets than in the case without turbulence. The eccentricities
+are still damped after planets become isolated. As a result, the number of
+final planets decreases with increase in strength of the turbulence, while
+Earth-mass planets with small eccentricities are still formed. In the case of
+relatively strong turbulence, the number of final planets are 4-5 at 0.5-2AU,
+which is consistent with Solar system, for relatively wide range of disk
+surface density (~10^{-4}-10^{-2} times MMSN).",0612619v1
+2007-01-18,Models of the Collisional Damping Scenario for Ice Giant Planets and Kuiper Belt Formatio,"Chiang et al. 2006, hereafter C06 have recently proposed that the observed
+structure of the Kuiper belt could be the result of a dynamical instability of
+a system of ~5 primordial ice giant planets in the outer Solar System.
+According to this scenario, before the instability occurred, these giants were
+growing in a highly collisionally damped environment according to the arguments
+in Goldreich et al. (2004a,b, hereafter G04). Here we test this hypothesis with
+a series of numerical simulations using a new code designed to incorporate the
+dynamical effects of collisions. We find that we cannot reproduce the observed
+Solar System. In particular, G04 and C06 argue that during the instability, all
+but two of the ice giants would be ejected from the Solar System by Jupiter and
+Saturn, leaving Uranus and Neptune behind. We find that ejections are actually
+rare and that instead the systems spread outward. This always leads to a
+configuration with too many planets that are too far from the Sun. Thus, we
+conclude that both G04's scheme for the formation of Uranus and Neptune and
+C06's Kuiper belt formation scenario are not viable in their current forms.",0701544v1
+2007-02-05,Ion Charge States in the Fast Solar Wind: New Data Analysis and Theoretical Refinements,"We present a further investigation into the increased ionization observed in
+element charge states in the fast solar wind compared to its coronal hole
+source regions. Once ions begin to be perpendicularly heated by ion cyclotron
+waves and execute large gyro-orbits, density gradients in the flow can excite
+lower hybrid waves that then damp by heating electrons in the parallel
+direction. We give further analysis of charge state data from polar coronal
+holes at solar minimum and maximum, and also from equatorial coronal holes. We
+also consider further the damping of lower hybrid waves by ions and the effect
+of non-Maxwellian electron distribution functions on the degree of increased
+ionization, both of which appear to be negligible for the solar wind case
+considered here. We also suggest that the density gradients required to heat
+electrons sufficiently to further ionize the solar wind can plausibly result
+from the turbulent cascade of MHD waves.",0702131v1
+1995-10-11,Multiple Transitions to Chaos in a Damped Parametrically Forced Pendulum,"We study bifurcations associated with stability of the lowest stationary
+point (SP) of a damped parametrically forced pendulum by varying $\omega_0$
+(the natural frequency of the pendulum) and $A$ (the amplitude of the external
+driving force). As $A$ is increased, the SP will restabilize after its
+instability, destabilize again, and so {\it ad infinitum} for any given
+$\omega_0$. Its destabilizations (restabilizations) occur via alternating
+supercritical (subcritical) period-doubling bifurcations (PDB's) and pitchfork
+bifurcations, except the first destabilization at which a supercritical or
+subcritical bifurcation takes place depending on the value of $\omega_0$. For
+each case of the supercritical destabilizations, an infinite sequence of PDB's
+follows and leads to chaos. Consequently, an infinite series of period-doubling
+transitions to chaos appears with increasing $A$. The critical behaviors at the
+transition points are also discussed.",9510003v1
+1996-03-04,Period Doublings in Coupled Parametrically Forced Damped Pendulums,"We study period doublings in $N$ $(N=2,3,4, \dots)$ coupled parametrically
+forced damped pendulums by varying $A$ (the amplitude of the external driving
+force) and $c$ (the strength of coupling). With increasing $A$, the stationary
+point undergoes multiple period-doubling transitions to chaos. We first
+investigate the two-coupled case with $N=2$. For each period-doubling
+transition to chaos, the critical set consists of an infinity of critical line
+segments and the zero-coupling critical point lying on the line $A=A^*_i$ in
+the $A-c$ plane, where $A^*_i$ is the $i$th transition point for the uncoupled
+case. We find three kinds of critical behaviors, depending on the position on
+the critical set. They are the same as those for the coupled one-dimensional
+maps. Finally, the results of the $N=2$ case are extended to many-coupled cases
+with $N \geq 3$, in which the critical behaviors depend on the range of
+coupling.",9603002v1
+1996-12-05,Fractal Basins of Attraction Associated with a Damped Newton's Method,"An intriguing and unexpected result for students learning numerical analysis
+is that Newton's method, applied to the simple polynomial z^3 - 1 = 0 in the
+complex plane, leads to intricately interwoven basins of attraction of the
+roots. As an example of an interesting open question that may help to stimulate
+student interest in numerical analysis, we investigate the question of whether
+a damping method, which is designed to increase the likelihood of convergence
+for Newton's method, modifies the fractal structure of the basin boundaries.
+The overlap of the frontiers of numerical analysis and nonlinear dynamics
+provides many other problems that can help to make numerical analysis courses
+interesting.",9612010v1
+1999-01-28,Intrinsically localized chaos in discrete nonlinear extended systems,"The phenomenon of intrinsic localization in discrete nonlinear extended
+systems, i.e. the (generic) existence of discrete breathers, is shown to be not
+restricted to periodic solutions but it also extends to more complex (chaotic)
+dynamical behaviour. We illustrate this with two different forced and damped
+systems exhibiting this type of solutions: In an anisotropic Josephson junction
+ladder, we obtain intrinsically localized chaotic solutions by following
+periodic rotobreather solutions through a cascade of period-doubling
+bifurcations. In an array of forced and damped van der Pol oscillators, they
+are obtained by numerical continuation (path-following) methods from the
+uncoupled limit, where its existence is trivially ascertained, following the
+ideas of the anticontinuum limit.",9901030v1
+1995-03-27,Dynamics of a Strongly Damped Two-Level System: Beyond the DBGA,"Dynamics of a dissipative two-level system is studied using quantum
+relaxation theory. This calculation for the first time goes beyond the commonly
+used dilute bounce gas approximation (DBGA), even for strong damping. The new
+results obtained here deviate from the DBGA results at low temperatures,
+however, the DBGA form is recovered at high temperatures. The results in the
+parameter regime $ 1/2<\alpha <1$, where the model has connection with the
+Kondo Hamiltonian, are of particular significance. In this regime, the spin
+shows a cross-over to a slower exponential relaxation at intermediate times,
+which is roughly half the relaxation rate at short times, as also observed in
+Quantum Monte-Carlo simulation of the model. The asymptotic behavior of the
+spin in the Kondo regime is in agreement with the exact conformal field theory
+results for the Kondo model. A connection of the dissipative dynamics of the
+two-level system with the quantum Zeno effect is also presented.",9503133v1
+1995-05-23,The phase-dependent linear conductance of a superconducting quantum point contact,"The exact expression for the phase-dependent linear conductance of a weakly
+damped superconducting quantum point contact is obtained. The calculation is
+performed by summing up the complete perturbative series in the coupling
+between the electrodes. The failure of any finite order perturbative expansion
+in the limit of small voltage and small quasi-particle damping is analyzed in
+detail. In the low transmission regime this nonperturbative calculation yields
+a result which is at variance with standard tunnel theory. Our result predicts
+the correct sign of the quasi-particle pair interference term and exhibits an
+unusual phase-dependence at low temperatures in qualitative agreement with the
+available experimental data.",9505102v1
+1996-02-27,Quasiparticle properties of a coupled quantum wire electron-phonon system,"We study leading-order many-body effects of longitudinal optical (LO) phonons
+on electronic properties of one-dimensional quantum wire systems. We calculate
+the quasiparticle properties of a weakly polar one dimensional electron gas in
+the presence of both electron-phonon and electron-electron interactions. The
+leading-order dynamical screening approximation (GW approximation) is used to
+obtain the electron self-energy, the quasiparticle spectral function, and the
+quasiparticle damping rate in our calculation by treating electrons and phonons
+on an equal footing. Our theory includes effects (within the random phase
+approximation) of Fermi statistics, Landau damping, plasmon-phonon mode
+coupling, phonon renormalization, dynamical screening, and impurity scattering.
+In general, electron-electron and electron-phonon many-body renormalization
+effects are found to be nonmultiplicative and nonadditive in our theoretical
+results for quasiparticle properties.",9602143v1
+1996-02-29,Dynamical response of a one dimensional quantum wire electron system,"We provide a self-contained theoretical analysis of the dynamical response of
+a one dimensional electron system, as confined in a semiconductor quantum wire,
+within the random phase approximation. We carry out a detailed comparison with
+the corresponding two and three dimensional situations, and discuss the
+peculiarities arising in the one dimensional linear response from the
+non-existence of low energy single-particle excitations and from the linear
+nature of the long wavelength plasmon mode. We provide a critical discussion of
+the analytic properties of the complex dielectric function in the complex
+frequency plane. We investigate the zeros of the complex dielectric function,
+and calculate the plasmon dispersion, damping, and plasmon spectral weight in
+one dimension. We consider finite temperature and impurity scattering effects
+on one dimensional plasmon dispersion and damping.",9602157v1
+1996-08-24,New Universality Class at the Superconductor--Insulator Transition,"We study dynamic properties of thin films near the superconductor - insulator
+transition. We formulate the problem in a phase representation. The key new
+feature of our model is the assumption of a {\it local} ohmic dissipative
+mechanism. Coarse graining leads to a Ginzburg-Landau description, with
+non-ohmic dynamics for the order parameter. For strong enough damping a new
+universality class is observed. It is characterized by a {\it non-universal}
+d.c. conductivity, and a damping dependent dynamical critical exponent. The
+formulation also provides a description of the magnetic field-tuned transition.
+Several microscopic mechanisms are proposed as the origin of the dissipation.",9608115v1
+1996-10-07,Supersymmetric Fokker-Planck strict isospectrality,"I report a study of the nonstationary one-dimensional Fokker-Planck solutions
+by means of the strictly isospectral method of supesymmetric quantum mechanics.
+The main conclusion is that this technique can lead to a space-dependent
+(modulational) damping of the spatial part of the nonstationary Fokker-Planck
+solutions, which I call strictly isospectral damping. At the same time, using
+an additive decomposition of the nonstationary solutions suggested by the
+strictly isospectral procedure and by an argument of Englefield [J. Stat. Phys.
+52, 369 (1988)], they can be normalized and thus turned into physical
+solutions, i.e., Fokker-Planck probability densities. There might be
+applications to many physical processes during their transient period",9610049v2
+1997-04-03,Quasiparticle Many-Body Dynamics of Highly Correlated Electronic Systems,"The self-consistent theory of the correlation effects in Highly Correlated
+Systems(HCS) is presented. The novel Irreducible Green's Functions(IGF) method
+is discused in detail for the Hubbard model and random Hubbard model. The
+interpolative solution for the quasiparticle spectrum, which is valid for both
+the atomic and band limit is obtained. The (IGF) method permits to calculate
+the quasiparticle spectra of many-particle systems with the complicated spectra
+and strong interaction in a very natural and compact way. The inelastic
+scattering corrections leads to the damping of the quasiparticles and are the
+main topic of the present consideration. The calculation of the damping has
+been done in a self-consistent way for both limits. For the random Hubbard
+model the weak coupling case has been considered and the self-energy operator
+has been calculated using the combination of the IGF method and Coherent
+Potential Approximation (CPA). The other applications of the method to s-f
+model, Anderson model, Heisenberg antiferromagnet, electron-phonon interaction
+models are discussed briefly.",9704028v1
+1997-12-17,Detecting flux creep in superconducting YBCO thin films via damping of the oscillations of a levitating permanent magnet,"The damping of the oscillations of a small permanent magnet (spherical shape,
+radius 0.1 mm) levitating between two parallel epitaxial YBCO films is measured
+as a function of oscillation amplitude and temperature. At small amplitudes the
+dissipation is found to be orders of magnitude lower than in bulk YBCO,
+Q-factors exceeding one million at low temperatures. With increasing amplitude
+the dissipation becomes exponentially large, exceeding the bulk values at large
+drives. We describe our results by calculating the ac shielding currents
+flowing through trapped flux whose motion gives rise to electric fields. We
+find dissipation to originate from different mechanisms of flux dynamics.",9712199v1
+1998-02-06,Spin polaron damping in the spin-fermion model for cuprate superconductors,"A self-consistent, spin rotational invariant Green's function procedure has
+been developed to calculate the spectral function of carrier excitations in the
+spin-fermion model for the CuO2 plane. We start from the mean field description
+of a spin polaron in the Mori-Zwanzig projection method. In order to determine
+the spin polaron lifetime in the self-consistent Born approximation, the
+self-energy is expressed by an irreducible Green's function. Both, spin polaron
+and bare hole spectral functions are calculated. The numerical results show a
+well pronounced quasiparticle peak near the bottom of the dispersion at
+(pi/2,pi/2), the absence of the quasiparticle at the Gamma-point, a rather
+large damping away from the minimum and an asymmetry of the spectral function
+with respect to the antiferromagnetic Brillouin zone. These findings are in
+qualitative agreement with photoemission data for undoped cuprates. The direct
+oxygen-oxygen hopping is responsible for a more isotropic minimum at
+(pi/2,pi/2).",9802074v1
+1998-02-24,Resonant steps and spatiotemporal dynamics in the damped dc-driven Frenkel-Kontorova chain,"Kink dynamics of the damped Frenkel-Kontorova (discrete sine-Gordon) chain
+driven by a constant external force are investigated. Resonant steplike
+transitions of the average velocity occur due to the competitions between the
+moving kinks and their radiated phasonlike modes. A mean-field consideration is
+introduced to give a precise prediction of the resonant steps. Slip-stick
+motion and spatiotemporal dynamics on those resonant steps are discussed. Our
+results can be applied to studies of the fluxon dynamics of 1D
+Josephson-junction arrays and ladders, dislocations, tribology and other
+fields.",9802251v1
+1998-05-09,The resonance peak in cuprate superconductors,"We pursue the consequences of a theory in which the resonance peak observed
+in inelastic neutron scattering (INS) experiments on underdoped and optimally
+doped YBa$_2$Cu$_3$O$_{6+x}$ compounds arises from a spin-wave excitation. We
+find that it is heavily damped, and thus almost not observable, in the normal
+state, but becomes visible in the superconducting state due to the drastic
+decrease in spin damping. We show that a spin-fermion model correctly describes
+the temperature dependence of the peak position for YBa$_2$Cu$_3$O$_7$, as well
+as the doping dependence of the peak position and of the integrated intensity.
+We explain why no resonance peak has been observed in La$_{2-x}$Sr$_x$CuO$_4$,
+and make several predictions concerning resonance peaks in other cuprate
+superconductors.",9805107v1
+1998-05-22,On the driven Frenkel-Kontorova model: I. Uniform sliding states and dynamical domains of different particle densities,"The dynamical behavior of a harmonic chain in a spatially periodic potential
+(Frenkel-Kontorova model, discrete sine-Gordon equation) under the influence of
+an external force and a velocity proportional damping is investigated. We do
+this at zero temperature for long chains in a regime where inertia and damping
+as well as the nearest-neighbor interaction and the potential are of the same
+order. There are two types of regular sliding states: Uniform sliding states,
+which are periodic solutions where all particles perform the same motion
+shifted in time, and nonuniform sliding states, which are quasi-periodic
+solutions where the system forms patterns of domains of different uniform
+sliding states. We discuss the properties of this kind of pattern formation and
+derive equations of motion for the slowly varying average particle density and
+velocity. To observe these dynamical domains we suggest experiments with a
+discrete ring of at least fifty Josephson junctions.",9805287v1
+1999-01-29,Acoustic radiation controls friction: Evidence from a spring-block experiment,"Brittle failures of materials and earthquakes generate acoustic/seismic waves
+which lead to radiation damping feedbacks that should be introduced in the
+dynamical equations of crack motion. We present direct experimental evidence of
+the importance of this feedback on the acoustic noise spectrum of
+well-controlled spring-block sliding experiments performed on a variety of
+smooth surfaces. The full noise spectrum is quantitatively explained by a
+simple noisy harmonic oscillator equation with a radiation damping force
+proportional to the derivative of the acceleration, added to a standard viscous
+term.",9901350v2
+1999-03-02,d_{x^2-y^2}-Wave Pairing Fluctuations and Pseudo Spin Gap in Two-Dimensional Electron Systems,"Pseudogap phenomena of high-T_c cuprates are examined. In terms of AFM
+(antiferromagnetic) and dSC (d_{x^2-y^2}-wave superconducting) auxiliary fields
+introduced to integrate out the fermions, the effective action for 2D electron
+systems with AFM and dSC fluctuations is considered. By the self-consistent
+renormalization (SCR), the NMR relaxation rate T_1^{-1}, the spin correlation
+length \xi_\sigma and the pairing correlation length \xi_d are calculated. From
+this calculation, a mechanism of the pseudogap formation emerges as the region
+of dominant d-wave short-range order (SRO) over AFM-SRO. When damping for the
+AFM fluctuation strongly depends on the dSC correlation length through the
+formation of precursor singlets around (\pi,0) and (0,\pi) points in the
+momentum space, the pseudogap appears in a region of the normal state
+characterized by decreasing 1/T_1T and increasing AFM correlation length with
+decrease in temperature. This reproduces a characteristic feature of the
+pseudogap phenomena in many underdoped cuprates. When the damping becomes
+insensitive to the dSC correlation length, the pseudogap region shrinks as in
+the overdoped cuprates.",9903030v2
+1999-03-11,Thermally activated escape rates of uniaxial spin systems with transverse field,"Classical escape rates of uniaxial spin systems are characterized by a
+prefactor differing from and much smaller than that of the particle problem,
+since the maximum of the spin energy is attained everywhere on the line of
+constant latitude: theta=const, 0 =< phi =< 2*pi. If a transverse field is
+applied, a saddle point of the energy is formed, and high, moderate, and low
+damping regimes (similar to those for particles) appear. Here we present the
+first analytical and numerical study of crossovers between the uniaxial and
+other regimes for spin systems. It is shown that there is one HD-Uniaxial
+crossover, whereas at low damping the uniaxial and LD regimes are separated by
+two crossovers.",9903192v2
+1999-04-19,Numerical analysis of the dissipative two-state system with the density-matrix Hilbert-space-reduction algorithm,"Ground state of the dissipative two-state system is investigated by means of
+the Lanczos diagonalization method. We adopted the Hilbert-space-reduction
+scheme proposed by Zhang, Jeckelmann and White so as to reduce the overwhelming
+reservoir Hilbert space to being tractable in computers. Both the
+implementation of the algorithm and the precision applied for the present
+system are reported in detail. We evaluate the dynamical susceptibility
+(resolvent) with the continued-fraction-expansion formula. Through analysing
+the resolvent over a frequency range, whose range is often called `interesting'
+frequency, we obtain the damping rate and the oscillation frequency. Our
+results agree with those of a recent quantum Monte-Carlo study, which concludes
+that the critical dissipation from oscillatory to over-damped behavior
+decreases as the tunneling amplitude is strengthened.",9904260v1
+1999-05-02,Finite Temperature Time-Dependent Effective Theory For The Goldstone Field In A BCS-Type Superfluid,"We extend to finite temperature the time-dependent effective theory for the
+Goldstone field (the phase of the pair field) $ \theta $ which is appropriate
+for a superfluid containing one species of fermions with s-wave interactions,
+described by the BCS Lagrangian. We show that, when Landau damping is
+neglected, the effective theory can be written as a local time-dependent
+non-linear Schr\""{o}dinger Lagrangian (TDNLSL) which preserves the Galilean
+invariance of the zero temperature effective theory and is identified with the
+superfluid component. We then calculate the relevant Landau terms which are
+non-local and which destroy the Galilean invariance. We show that the retarded
+$\theta$-propagator (in momentum space) can be well represented by two poles in
+the lower-half frequency plane, describing damping with a predicted
+temperature, frequency and momentum dependence. It is argued that the real
+parts of the Landau terms can be approximately interpreted as contributing to
+the normal fluid component.",9905008v2
+1999-06-29,Simulation of I-V Hysteresis Branches in An Intrinsic Stack of Josephson Junctions in High $T_c$ Superconductors,"I-V characteristics of the high T$_c$ superconductor
+Bi$_2$Sr$_2$Ca$_1$C$_2$O$_8$ shows a strong hysteresis, producing many
+branches. The origin of hysteresis jumps is studied by use of the model of
+multi-layered Josephson junctions proposed by one of the authors (T. K.). The
+charging effect at superconducting layers produces a coupling between the next
+nearest neighbor phase-differences, which determines the structure of
+hysteresis branches. It will be shown that a solution of phase motions is
+understood as a combination of rotating and oscillating phase-differences, and
+that, at points of hysteresis jumps, there occurs a change in the number of
+rotating phase-differences. Effects of dissipation are analyzed. The
+dissipation in insulating layers works to damp the phase motion itself, while
+the dissipation in superconducting layers works to damp relative motions of
+phase-differences. Their effects to hysteresis jumps are discussed.",9906422v1
+1999-07-05,The interplay between flattening and damping of single particle spectra in strongly correlated Fermi systems,"The self-consistent theory of the fermion condensation, a specific phase
+transition which results in a rearrangement of the single particle degrees of
+freedom in strongly correlated Fermi systems is developed. Beyond the phase
+transition point, the single particle spectra are shown to be flat. The
+interplay between the flattening and the damping of the single particle spectra
+at $T\to 0$ is investigated. The width $\gamma(\epsilon)$ of the single
+particle states is found to grow up linearly with $\epsilon$ over a wide range
+of energy as in a marginal Fermi liquid. Our results gain insight into the
+success of the phenomenological theory of the normal states of high-temperature
+superconductors by Varma et al.",9907061v1
+1999-10-19,Zener transitions between dissipative Bloch bands. II: Current Response at Finite Temperature,"We extend, to include the effects of finite temperature, our earlier study of
+the interband dynamics of electrons with Markoffian dephasing under the
+influence of uniform static electric fields. We use a simple two-band
+tight-binding model and study the electric current response as a function of
+field strength and the model parameters. In addition to the Esaki-Tsu peak,
+near where the Bloch frequency equals the damping rate, we find current peaks
+near the Zener resonances, at equally spaced values of the inverse electric
+field. These become more prominenent and numerous with increasing bandwidth (in
+units of the temperature, with other parameters fixed). As expected, they
+broaden with increasing damping (dephasing).",9910290v1
+1999-11-02,Shifts and widths of collective excitations in trapped Bose gases by the dielectric formalism,"We present predictions for the temperature dependent shifts and damping
+rates. They are obtained by applying the dielectric formalism to a simple model
+of a trapped Bose gas. Within the framework of the model we use lowest order
+perturbation theory to determine the first order correction to the results of
+Hartree-Fock-Bogoliubov-Popov theory for the complex collective excitation
+frequencies, and present numerical results for the temperature dependence of
+the damping rates and the frequency shifts. Good agreement with the
+experimental values measured at JILA are found for the m=2 mode, while we find
+disagreements in the shifts for m=0. The latter point to the necessity of a
+non-perturbative treatment for an explanation of the temperature-dependence of
+the m=0 shifts.",9911018v1
+2000-06-13,Characteristic features of anharmonic effects in the lattice dynamics of fcc metals,"The dispersion in the entire Brillouin zone and the temperature dependence
+(right up to the melting temperature) of the anharmonic frequency shift and
+phonon damping in a number of fcc metals is investigated on the basis of
+microscopic calculations. It is found that the anharmonic effects depend
+sharply on the wave vector in the directions $\Gamma$-X, X-W, and $\Gamma$-L
+and, in contrast to bcc metals, the magnitude of the effects is not due to the
+softness of the initial phonon spectrum. It is shown that the relative
+frequency shifts and the phonon damping near melting do not exceed 10-20%. The
+relative role of various anharmonic processes is examined, and the relation
+between the results obtained and existing experimental data is discussed.",0006205v1
+2000-06-20,Collisional damping of the collective oscillations of a trapped Fermi gas,"We consider a Fermi gas confined by a harmonic trapping potential and we
+highlight the role of the Fermi-Dirac statistics by studying frequency and
+damping of collective oscillations of quadrupole type in the framework of the
+quantum Boltzmann equation, in which statistical corrections are taken into
+account in the collisional integral. We are able to describe the crossover from
+the collisionless regime to the hydrodynamic one by introducing a
+temperature-dependent relaxation time $\tau_Q$. We show that, in the degenerate
+regime, the relaxation rate $1/\tau_Q$ exhibits a temperature dependence
+different from the collision rate $\gamma$. We finally compare the collisional
+properties of the Fermi gas with the ones of the Bose gas for temperatures
+above the Bose-Einstein condensation.",0006305v2
+2000-06-21,Resonances in the dynamics of $φ^4$ kinks perturbed by ac forces,"We study the dynamics of $\phi^4$ kinks perturbed by an ac force, both with
+and without damping. We address this issue by using a collective coordinate
+theory, which allows us to reduce the problem to the dynamics of the kink
+center and width. We carry out a careful analysis of the corresponding ordinary
+differential equations, of Mathieu type in the undamped case, finding and
+characterizing the resonant frequencies and the regions of existence of
+resonant solutions. We verify the accuracy of our predictions by numerical
+simulation of the full partial differential equation, showing that the
+collective coordinate prediction is very accurate. Numerical simulations for
+the damped case establish that the strongest resonance is the one at half the
+frequency of the internal mode of the kink. In the conclusion we discuss on the
+possible relevance of our results for other systems, especially the sine-Gordon
+equation. We also obtain additional results regarding the equivalence between
+different collective coordinate methods applied to this problem.",0006313v1
+2000-07-11,Quantum phase transitions in d-wave superconductors,"Motivated by the strong, low temperature damping of nodal quasiparticles
+observed in some cuprate superconductors, we study quantum phase transitions in
+d_{x^2-y^2} superconductors with a spin-singlet, zero momentum, fermion
+bilinear order parameter. We present a complete, group-theoretic classification
+of such transitions into 7 distinct cases (including cases with nematic order)
+and analyze fluctuations by the renormalization group. We find that only 2, the
+transitions to d_{x^2-y^2}+is and d_{x^2-y^2} + i d_{xy} pairing, possess
+stable fixed points with universal damping of nodal quasiparticles; the latter
+leaves the gapped quasiparticles along (1,0), (0,1) essentially undamped.",0007170v3
+2000-07-12,Frequencies and Damping rates of a 2D Deformed Trapped Bose gas above the Critical Temperature,"We derive the equation of motion for the velocity fluctuations of a 2D
+deformed trapped Bose gas above the critical temperature in the hydrodynamical
+regime. From this equation, we calculate the eigenfrequencies for a few
+low-lying excitation modes. Using the method of averages, we derive a
+dispersion relation in a deformed trap that interpolates between the
+collisionless and hydrodynamic regimes. We make use of this dispersion relation
+to calculate the frequencies and the damping rates for monopole and quadrupole
+mode in both the regimes. We also discuss the time evolution of the wave packet
+width of a Bose gas in a time dependent as well as time independent trap.",0007210v2
+2000-09-01,The Broad Brillouin Doublet and CP of Ktao_3 : Second Sound vs. Two-Phonon Difference Scattering,"Low-T Brillouin spectra of the incipient ferroelectric KTaO3 exhibit a broad
+central peak (CP), and additional Brillouin doublets (BD), that can both be
+related to phonon-density fluctuations. On the basis of new high-resolution
+neutron data obtained of low-lying phonon branches, we analysed the
+phonon-kinetics mechanisms that are possibly the origin of these unusual
+features. Firstly, transverse acoustic (TA) phonons whose normal damping is
+faster than the BD frequency can produce hydrodynamic second sound. Secondly,
+two-phonon difference scattering from low damping thermal transverse phonons
+contribute to the spectra with either a sharp or a broader doublet, depending
+on the phonon group velocity and anisotropy of dispersion surfaces. The
+position of the observed sharp doublet is consistent with both mechanisms, but
+a comparison of the computed and experimental anisotropies favours the second
+process.",0009011v1
+2000-12-29,Finite Temperature Time-Dependent Effective Theory for the Phase Field in two-dimensional d-wave Neutral Superconductor,"We derive finite temperature time-dependent effective actions for the phase
+of the pairing field, which are appropriate for a 2D electron system with both
+non-retarded d- and s-wave attraction. As for s-wave pairing the d-wave
+effective action contains terms with Landau damping, but their structure
+appears to be different from the s-wave case due to the fact that the Landau
+damping is determined by the quasiparticle group velocity v_{g}, which for
+d-wave pairing does not have the same direction as the non-interacting Fermi
+velocity v_{F}. We show that for d-wave pairing the Landau term has a linear
+low temperature dependence and in contrast to the s-wave case are important for
+all finite temperatures. A possible experimental observation of the phase
+excitations is discussed.",0012511v4
+2001-01-23,Ginzburg-Landau theory for the time-dependent phase field in a two-dimensional d-wave superconductor,"We derive a finite temperature time-dependent effective theory for the phase
+$\theta$ of the pairing field, which is appropriate for a 2D conducting
+electron system with non-retarded d-wave attraction. As for s-wave pairing the
+effective action contains terms with Landau damping, but their structure
+appears to be different from the s-wave case due to the fact that the Landau
+damping is determined by the quasiparticle group velocity $v_g$, which for the
+d-wave pairing does not have the same direction as the non-interacting Fermi
+velocity $v_F$. We show that for the d-wave pairing the Landau terms have a
+linear low temperature dependence and in contrast to the s-wave case are
+important for all finite temperatures.",0101353v1
+2001-06-05,Damping and frequency shift in the oscillations of two colliding Bose-Einstein condensates,"We have investigated the center-of-mass oscillations of a Rb87 Bose-Einstein
+condensate in an elongated magneto-static trap. We start from a trapped
+condensate and we transfer part of the atoms to another trapped level, by
+applying a radio-frequency pulse. The new condensate is produced far from its
+equilibrium position in the magnetic potential, and periodically collides with
+the parent condensate. We discuss how both the damping and the frequency shift
+of the oscillations are affected by the mutual interaction between the two
+condensates, in a wide range of trapping frequencies. The experimental data are
+compared with the prediction of a mean-field model.",0106072v1
+2001-07-12,Ferromagnetism in the Hubbard model,"We investigate the possibility and stability of bandferromagnetism in the
+single-band Hubbard model. This model poses a highly non-trivial many-body
+problem the general solution of which has not been found up to now.
+Approximations are still unavoidable. Starting from a simple two-pole ansatz
+for the spectral density our approach is systematically improved by focusing on
+the influence of quasiparticle damping and the correct weak-and strong coupling
+behaviour. The compatibility of the different aproximative steps with decisive
+moment sum rules is analysed and the importance of a spin-dependent band shift
+mediated by higher correlation functions is worked out. Results are presented
+in terms of temperature- and band occupation-dependent quasiparticle densities
+of states and band structures as well as spontaneous magnetisations,
+susceptibilities and Curie temperatures for varying electron densities and
+coupling strengths. Comparison is made to numerically essentially exact Quantum
+Monte Carlo calculations recently done by other authors using dynamical mean
+field theory for infinite-dimensional lattices. The main conclusion will be
+that the Hubbard model provides a qualitatively correct description of
+bandferromagnetism if quasiparticle damping and selfconsistent spin-dependent
+bandshifts are properly taken into account.",0107255v1
+2001-09-10,Finite temperature theory of the scissors mode in a Bose gas using the moment method,"We use a generalized Gross-Pitaevskii equation for the condensate and a
+semi-classical kinetic equation for the noncondensate atoms to discuss the
+scissors mode in a trapped Bose-condensed gas at finite temperatures. Both
+equations include the effect of $C_{12}$ collisions between the condensate and
+noncondensate atoms. We solve the coupled moment equations describing
+oscillations of the quadrupole moments of the condensate and noncondensate
+components to find the collective mode frequencies and collisional damping
+rates as a function of temperature. Our calculations extend those of
+Gu\'ery-Odelin and Stringari at T=0 and in the normal phase. They complement
+the numerical results of Jackson and Zaremba, although Landau damping is left
+out of our approach. Our results are also used to calculate the quadrupole
+response function, which is related to the moment of inertia. It is shown
+explicitly that the moment of inertia of a trapped Bose gas at finite
+temperatures involves a sum of an irrotational component from the condensate
+and a rotational component from the thermal cloud atoms.",0109149v1
+2002-01-24,Dynamic light scattering from colloidal fractal monolayers,"We address experimentally the problem of how the structure of a surface
+monolayer determines the visco-elasticity of the interface. Optical microscopy
+and surface quasi--elastic light scattering have been used to characterize
+aggregation of CaCO$_3$ particles at the air--water interface. The structures
+formed by cluster-cluster aggregation are two dimensional fractals which grow
+to eventually form a percolating network. This process is measured through
+image analysis. On the same system we measure the dynamics of interfacial
+thermal fluctuations (surface ripplons), and we discuss how the relaxation
+process is affected by the growing clusters. We show that the structures start
+damping the ripplons strongly when the two length scales are comparable. No
+macroscopic surface pressure is measured and this is in contrast to lipid,
+surfactant or polymer monolayers at concentrations corresponding to surface
+coverage. This observation and the difficulty in fitting the ripplon spectrum
+with traditional models suggest that a different physical mechanism might be
+responsible for the observed damping of ripplons in this system.",0201438v1
+2002-08-08,Excitation and damping of collective modes of a Bose-Einstein condensate in a one-dimensional lattice,"The mode structure of a Bose-Einstein condensate non-adiabatically loaded
+into a one-dimensional optical lattice is studied by analyzing the visibility
+of the interference pattern as well as the radial profile of the condensate
+after a time-of-flight. A simple model is proposed that predicts the short-time
+decrease of the visibility as a function of the condensate parameters. In the
+radial direction, heavily damped oscillations are observed, as well as an
+increase in the condensate temperature. These findings are interpreted as a
+re-thermalization due to dissipation of the initial condensate excitations into
+high-lying modes.",0208162v1
+2002-08-12,Spectral Properties of the Generalized Spin-Fermion Models,"In order to account for competition and interplay of localized and itinerant
+magnetic behaviour in correlated many body systems with complex spectra the
+various types of spin-fermion models have been considered in the context of the
+Irreducible Green's Functions (IGF) approach. Examples are generalized d-f
+model and Kondo-Heisenberg model. The calculations of the quasiparticle
+excitation spectra with damping for these models has been performed in the
+framework of the equation- of-motion method for two-time temperature Green's
+Functions within a non-perturbative approach. A unified scheme for the
+construction of Generalized Mean Fields (elastic scattering corrections) and
+self-energy (inelastic scattering) in terms of the Dyson equation has been
+generalized in order to include the presence of the two interacting subsystems
+of localized spins and itinerant electrons. A general procedure is given to
+obtain the quasiparticle damping in a self-consistent way. This approach gives
+the complete and compact description of quasiparticles and show the flexibility
+and richness of the generalized spin-fermion model concept.",0208227v1
+2002-08-13,Itinerant Antiferromagnetism of Correlated Lattice Fermions,"The problem of finding of the ferromagnetic and antiferromagnetic ""symmetry
+broken"" solutions of the correlated lattice fermion models beyond the
+mean-field approximation has been investigated. The calculation of the
+quasiparticle excitation spectra with damping for the single- and multi-orbital
+Hubbard model has been performed in the framework of the equation- of-motion
+method for two-time temperature Green's Functions within a non-perturbative
+approach. A unified scheme for the construction of Generalized Mean Fields
+(elastic scattering corrections) and self-energy (inelastic scattering) in
+terms of the Dyson equation has been generalized in order to include the
+presence of the ""source fields"". The damping of quasiparticles, which reflects
+the interaction of the single-particle and collective degrees of freedom has
+been calculated. The ""symmetry broken"" dynamical solutions of the Hubbard
+model, which correspond to various types of itinerant antiferromagnetism has
+been discussed. This approach complements previous studies and clarifies the
+nature of the concepts of itinerant antiferromagnetism and ""spin-aligning
+field"" of correlated lattice fermions.",0208242v1
+2003-01-21,Zero temperature damping of Bose-Einstein condensate oscillations by vortex-antivortex pair creation,"We investigate vortex-antivortex pair creation in a supersonically expanding
+and contracting quasi-2D Bose-Einstein condensate at zero temperature. For
+sufficiently large amplitude condensate oscillations, pair production provides
+the leading dissipation mechanism. The condensate oscillations decay in a
+nonexponential fashion, and the dissipation rate depends strongly on the
+oscillation amplitude. These features allow to distinguish the decay due to
+pair creation from other possible damping mechanisms. Experimental observation
+of the predicted oscillation behavior of the superfluid gas provides a direct
+confirmation of the hydrodynamical analogy of quantum electrodynamics and
+quantum vortex dynamics in two spatial dimensions.",0301397v3
+2003-02-10,Damped orbital excitations in the titanates,"A possible mechanism for the removal of the orbital degeneracy in RTiO3
+(where R=La, Y, ...) is considered. The calculation is based on the
+Kugel-Khomskii Hamiltonian for electrons residing in the t2g orbitals of the Ti
+ions, and uses a self-consistent pe rturbation expansion in the interaction
+between the orbital and the spin degrees of freedom. The latter are assumed to
+be ordered in a Neel state, brought about by delicate interactions that are not
+included in the Kugel-Khomskii Hamiltonian. Within our model calculations, each
+of the t2g bands is found to acquire a finite, temperature-dependent
+dispersion, that lifts the orbital degeneracy. The orbital excitations are
+found to be heavily damped over a rather wide band. Consequently, they do not
+participate as a separate branch of excitations in the low-temperature
+thermodynamics.e",0302182v1
+2003-03-20,Energies and damping rates of elementary excitations in spin-1 Bose-Einstein condensed gases,"Finite temperature Green's function technique is used to calculate the
+energies and damping rates of elementary excitations of the homogeneous,
+dilute, spin-1 Bose gases below the Bose-Einstein condensation temperature both
+in the density and spin channels. For this purpose the self-consistent
+dynamical Hartree-Fock model is formulated, which takes into account the direct
+and exchange processes on equal footing by summing up certain classes of
+Feynman diagrams. The model is shown to fulfil the Goldstone theorem and to
+exhibit the hybridization of one-particle and collective excitations correctly.
+The results are applied to the gases of ^{23}Na and ^{87}Rb atoms.",0303424v3
+2003-04-17,Non-Fermi liquid behavior from two-dimensional antiferromagnetic fluctuations: a renormalization-group and large-N analysis,"We analyze the Hertz-Moriya-Millis theory of an antiferromagnetic quantum
+critical point, in the marginal case of two dimensions (d=2,z=2). Up to
+next-to-leading order in the number of components (N) of the field, we find
+that logarithmic corrections do not lead to an enhancement of the Landau
+damping. This is in agreement with a renormalization-group analysis, for
+arbitrary N. Hence, the logarithmic effects are unable to account for the
+behavior reportedly observed in inelastic neutron scattering experiments on
+CeCu_{6-x}Au_x. We also examine the extended dynamical mean-field treatment
+(local approximation) of this theory, and find that only subdominant
+corrections to the Landau damping are obtained within this approximation, in
+contrast to recent claims.",0304415v1
+2003-05-21,The path-coalescence transition and its applications,"We analyse the motion of a system of particles subjected a random force
+fluctuating in both space and time, and experiencing viscous damping. When the
+damping exceeds a certain threshold, the system undergoes a phase transition:
+the particle trajectories coalesce. We analyse this transition by mapping it to
+a Kramers problem which we solve exactly. In the limit of weak random force we
+characterise the dynamics by computing the rate at which caustics are crossed,
+and the statistics of the particle density in the coalescing phase. Last but
+not least we describe possible realisations of the effect, ranging from
+trajectories of raindrops on glass surfaces to animal migration patterns.",0305491v2
+2003-05-21,Magnetoresistive response of a high mobility 2DES under electromagnetic wave excitation,"Oscillations of the resistance observed under electromagnetic wave excitation
+in the high mobility GaAs/AlGaAs 2DES are examined as a function of the
+radiation frequency and the power, utilizing an empirical lineshape based on
+exponentially damped sinusoids. The fit-analysis indicates the resistance
+oscillation frequency, F, increases with the radiation frequency, n, at the
+rate dF/dn = 2.37 mTesla/GHz; the damping parameter, a, is approximately
+independent of n at constant power; and the amplitude, A, of the oscillations
+grows slowly with the incident power, at a constant temperature and frequency.
+The lineshape appears to provide a good description of the data.",0305507v2
+2003-06-16,Infrared Spectroscopy of Quantum Crossbars,"Infrared (IR) spectroscopy can be used as an important and effective tool for
+probing periodic networks of quantum wires or nanotubes (quantum crossbars,
+QCB) at finite frequencies far from the Luttinger liquid fixed point. Plasmon
+excitations in QCB may be involved in resonance diffraction of incident
+electromagnetic waves and in optical absorption in the IR part of the spectrum.
+Direct absorption of external electric field in QCB strongly depends on the
+direction of the wave vector ${\bf q}.$ This results in two types of $1D\to 2D$
+dimensional crossover with varying angle of an incident wave or its frequency.
+In the case of QCB interacting with semiconductor substrate, capacitive contact
+between them does not destroy the Luttinger liquid character of the long wave
+QCB excitations. However, the dielectric losses on a substrate surface are
+significantly changed due to appearance of additional Landau damping. The
+latter is initiated by diffraction processes on QCB superlattice and manifests
+itself as strong but narrow absorption peaks lying below the damping region of
+an isolated substrate.Submi",0306409v1
+2003-06-19,Superradiant light scattering from a moving Bose-Einstein condensate,"We investigate the interaction of a moving BEC with a far detuned laser beam.
+Superradiant Rayleigh scattering arises from the spontaneous formation of a
+matter-wave grating due to the interference of two wavepackets with different
+momenta. The system is described by the CARL-BEC model which is a
+generalization of the Gross-Pitaevskii model to include the self-consistent
+evolution of the scattered field. The experiment gives evidence of a damping of
+the matter-wave grating which depends on the initial velocity of the
+condensate. We describe this damping in terms of a phase-diffusion decoherence
+process, in good agreement with the experimental results.",0306500v2
+2003-07-25,Finite temperature excitations of a trapped Bose-Fermi mixture,"We present a detailed study of the low-lying collective excitations of a
+spherically trapped Bose-Fermi mixture at finite temperature in the
+collisionless regime. The excitation frequencies of the condensate are
+calculated self-consistently using the static Hartree-Fock-Bogoliubov theory
+within the Popov approximation. The frequency shifts and damping rates due to
+the coupled dynamics of the condensate, noncondensate, and degenerate Fermi gas
+are also taken into account by means of the random phase approximation and
+linear response theory. In our treatment, the dipole excitation remains close
+to the bare trapping frequency for all temperatures considered, and thus is
+consistent with the generalized Kohn theorem. We discuss in some detail the
+behavior of monopole and quadrupole excitations as a function of the Bose-Fermi
+coupling. At nonzero temperatures we find that, as the mixture moves towards
+spatial separation with increasing Bose-Fermi coupling, the damping rate of the
+monopole (quadrupole) excitation increases (decreases). This provides us a
+useful signature to identify the phase transition of spatial separation.",0307638v1
+2003-09-18,Memory-function approach to the normal-state optical properties of the Bechgaard salt (TMTSF)_2PF_6,"The gauge invariant, two-component optical conductivity model, with a
+correlation gap structure related to the umklapp scattering processes, is
+applied to the quasi-one-dimensional electronic systems and compared to the
+recent measurements on the Bechgaard salt (TMTSF)_2PF_6. The optical response
+of both the insulating and metallic state is found for the half-filled
+conduction band, depending on the ratio between the correlation energy scale 2
+\Delta^0_2 and the transfer integral in the direction perpendicular to the
+conducting chains, t_{{\rm b}'}. The estimated value 2 \Delta^0_2/t_{{\rm b}'}
+agrees reasonably well with the previous experimental and theoretical
+conclusions. Parallel to the chains the thermally activated conduction
+electrons in the insulating state are found to exhibit an universal behaviour,
+accounting for the observed single-particle optical conductivity of the ordered
+ground state of charge-density-wave systems. The band parameters and the
+related damping energies suitable to the normal metallic state of (TMTSF)_2PF_6
+are estimated from the measured spectra. Not only the spectral weights but also
+the damping energies clearly indicate an opening of the correlation gap in the
+charge excitation spectrum",0309419v1
+2003-10-03,Effects of electrostatic fields and Casimir force on cantilever vibrations,"The effect of an external bias voltage and fluctuating electromagnetic fields
+on both the fundamental frequency and damping of cantilever vibrations is
+considered. An external voltage induces surface charges causing
+cantilever-sample electrostatic attraction. A similar effect arises from
+charged defects in dielectrics that cause spatial fluctuations of electrostatic
+fields. The cantilever motion results in charge displacements giving rise to
+Joule losses and damping. It is shown that the dissipation increases with
+decreasing conductivity and thickness of the substrate, a result that is
+potentially useful for sample diagnostics. Fluctuating electromagnetic fields
+between the two surfaces also induce attractive (Casimir) forces. It is shown
+that the shift in the cantilever fundamental frequency due to the Casimir force
+is close to the shift observed in recent experiments of Stipe et al. Both the
+electrostatic and Casimir forces have a strong effect on the cantilever
+eigenfrequencies, and both effects depend on the geometry of the cantilever
+tip. We consider cylindrical, spherical, and ellipsoidal tips moving parallel
+to a flat sample surface. The dependence of the cantilever effective mass and
+vibrational frequencies on the geometry of the tip is studied both numerically
+and analytically.",0310081v1
+2003-10-07,Precessional switching of thin nanomagnets: analytical study,"We study analytically the precessional switching of the magnetization of a
+thin macrospin. We analyze its response when subjected to an external field
+along its in-plane hard axis. We derive the exact trajectories of the
+magnetization. The switching versus non switching behavior is delimited by a
+bifurcation trajectory, for applied fields equal to half of the effective
+anisotropy field. A magnetization going through this bifurcation trajectory
+passes exactly along the hard axis and exhibits a vanishing characteristic
+frequency at that unstable point, which makes the trajectory noise sensitive.
+Attempting to approach the related minimal cost in applied field makes the
+magnetization final state unpredictable. We add finite damping in the model as
+a perturbative, energy dissipation factor. For a large applied field, the
+system switches several times back and forth. Several trajectories can be gone
+through before the system has dissipated enough energy to converge to one
+attracting equilibrium state. For some moderate fields, the system switches
+only once by a relaxation dominated precessional switching. We show that the
+associated switching field increases linearly with the damping parameter. The
+slope scales with the square root of the effective anisotropy. Our simple
+concluding expressions are useful to assess the potential application of
+precessional switching in magnetic random access memories.",0310147v1
+2003-11-27,Temperature dependent Bogoliubov approximation in the classical fields approach to weakly interacting Bose gas,"A classical fields approximation to the finite temperature microcanonical
+thermodynamics of weakly interacting Bose gas is applied to the idealized case
+of atoms confined in a box with periodic boundary conditions. We analyze in
+some detail the microcanonical temperature in the model. We also analyze the
+spectral properties of classical amplitudes of the plane waves -- the
+eigenmodes of the time averaged one--particle density matrix. Looking at the
+zero momentum component -- the order parameter of the condensate, we obtain the
+nonperturbative results for the chemical potential. Analogous analysis of the
+other modes yields nonperturbative temperature dependent Bogoliubov frequencies
+and their damping rates. Damping rates are linear functions of momenta in the
+phonon range and show more complex behavior for the particle sector. Where
+available, we make comparison with the analytic estimates of these quantities.",0311622v1
+2003-12-29,Plasmon attenuation and optical conductivity of a two-dimensional electron gas,"In a ballistic two-dimensional electron gas, the Landau damping does not lead
+to plasmon attenuation in a broad interval of wave vectors q << k_F. Similarly,
+it does not contribute to the optical conductivity \sigma (\omega, q) in a wide
+domain of its arguments, E_F > \omega > qv_F, where E_F, k_F and v_F are,
+respectively, the Fermi energy, wavevector and velocity of the electrons. We
+identify processes that result in the plasmon attenuation in the absence of
+Landau damping. These processes are: the excitation of two electron-hole pairs,
+phonon-assisted excitation of one pair, and a direct plasmon-phonon conversion.
+We evaluate the corresponding contributions to the plasmon linewidth and to the
+optical conductivity.",0312684v3
+2004-03-05,Mode-coupling theory and molecular dynamics simulation for heat conduction in a chain with transverse motions,"We study heat conduction in a one-dimensional chain of particles with
+longitudinal as well as transverse motions. The particles are connected by
+two-dimensional harmonic springs together with bending angle interactions. The
+problem is analyzed by mode-coupling theory and compared with molecular
+dynamics. We find very good, quantitative agreement for the damping of modes
+between a full mode-coupling theory and molecular dynamics result, and a
+simplified mode-coupling theory gives qualitative description of the damping.
+The theories predict generically that thermal conductance diverges as N^{1/3}
+as the size N increases for systems terminated with heat baths at the ends. The
+N^{2/5} dependence is also observed in molecular dynamics which we attribute to
+crossover effect.",0403162v1
+2004-03-21,Evidence for Superfluidity in a Resonantly Interacting Fermi Gas,"We observe collective oscillations of a trapped, degenerate Fermi gas of
+$^6$Li atoms at a magnetic field just above a Feshbach resonance, where the
+two-body physics does not support a bound state. The gas exhibits a radial
+breathing mode at a frequency of 2837(05) Hz, in excellent agreement with the
+frequency of $\nu_H\equiv\sqrt{10\nu_x\nu_y/3}=2830(20)$ Hz predicted for a
+{\em hydrodynamic} Fermi gas with unitarity limited interactions. The measured
+damping times and frequencies are inconsistent with predictions for both the
+collisionless mean field regime and for collisional hydrodynamics. These
+observations provide the first evidence for superfluid hydrodynamics in a
+resonantly interacting Fermi gas.",0403540v2
+2004-03-22,Parametric Driving of Dark Solitons in Atomic Bose-Einstein Condensates,"A dark soliton oscillating in an elongated harmonically-confined atomic
+Bose-Einstein condensate continuously exchanges energy with the sound field.
+Periodic optical `paddles' are employed to controllably enhance the sound
+density and transfer energy to the soliton, analogous to parametric driving. In
+the absence of damping, the amplitude of the soliton oscillations can be
+dramatically reduced, whereas with damping, a driven soliton equilibrates as a
+stable dark soliton with lower energy, thereby extending the soliton lifetime
+up to the lifetime of the condensate.",0403566v2
+2004-04-09,Network-Induced Oscillatory Behavior in Material Flow Networks,"Network theory is rapidly changing our understanding of complex systems, but
+the relevance of topological features for the dynamic behavior of metabolic
+networks, food webs, production systems, information networks, or cascade
+failures of power grids remains to be explored. Based on a simple model of
+supply networks, we offer an interpretation of instabilities and oscillations
+observed in biological, ecological, economic, and engineering systems. We find
+that most supply networks display damped oscillations, even when their units -
+and linear chains of these units - behave in a non-oscillatory way. Moreover,
+networks of damped oscillators tend to produce growing oscillations. This
+surprising behavior offers, for example, a new interpretation of business
+cycles and of oscillating or pulsating processes. The network structure of
+material flows itself turns out to be a source of instability, and cyclical
+variations are an inherent feature of decentralized adjustments.",0404226v1
+2004-04-28,Dynamics of the Electro-Reflective Response of TaS3,"We have observed a large (~1%) change in infrared reflectance of the
+charge-density-wave (CDW) conductor, orthorhombic TaS3, when its CDW is
+depinned. The change is concentrated near one current contact. Assuming that
+the change in reflectance is proportional to the degree of CDW polarization, we
+have studied the dynamics of CDW repolarization through position dependent
+measurements of the variation of the electro-reflectance with the frequency of
+square wave voltages applied to the sample, and have found that the response
+could be characterized as a damped harmonic oscillator with a distribution of
+relaxation (i.e. damping) times. The average relaxation time, which increases
+away from the contacts, varies with applied voltage as t0 ~ 1/V^p with p ~ 3/2,
+but the distribution of times broadens as the voltage approaches the depinning
+threshold. Very low resonant frequencies (~ 1 kHz) indicate a surprisingly
+large amount of inertia, which is observable in the time dependence of the
+change in reflectance as a polarity dependent delay of ~ 100 microsec.",0404690v1
+2004-05-06,Damping of the de Haas-van Alphen oscillations in the superconducting state of MgB_2,"The de Haas-van Alphen (dHvA) signal arising from orbits on the $\pi$ Fermi
+surface sheet of the two-gap superconductor MgB$_2$ has been observed in the
+vortex state below $H_{c2}$. An extra attenuation of the dHvA signal, beyond
+those effects described in the conventional Lifshitz-Kosevich expression, is
+seen due to the opening of the superconducting gap. Our data show that the
+$\pi$ band gap is still present up to $H_{c2}$. The data are compared to
+current theories of dHvA oscillations in the superconducting state which allow
+us to extract estimates for the evolution of the $\pi$ band gap with magnetic
+field. Contrary to results for other materials, we find that the most recent
+theories dramatically underestimate the damping in MgB$_2$.",0405120v1
+2004-05-26,Magnetic droplets in a metal close to a ferromagnetic quantum critical point,"Using analytical and path integral Monte Carlo methods, we study the
+susceptibility $\chi_{dc}(T)$ of a spin-S impurity with XY rotational symmetry
+embedded in a metal. Close to a ferromagnetic quantum critical point, the
+impurity polarizes conduction electrons in its vicinity and forms a large
+magnetic droplet with moment M>>S. At not too low temperatures, the strongly
+damping paramagnon modes of the conduction electrons suppress large quantum
+fluctuations (or spin flips) of this droplet. We show that the susceptibility
+follows the law $\chi_{dc}(T)=(M^{2}/T)[1-(\pi g)^{-1}\ln(gE_{0}/T)]$, where
+the parameter g>>1 describes the strong damping by conduction electrons, and
+E_0 is the bandwidth of paramagnon modes. At exponentially low temperatures T
+<< T_{*} ~ E_{0}\exp(-\pi g/2) we show that spin flips cannot be ignored. In
+this regime we find that $\chi_{dc}(T) \approx \chi_{dc}(0)
+[1-(2/3)(T/T_{*})^2]$, where $\chi_{dc}(0)\sim M^{2}/T_{*}$ is finite and
+exponentially large in g. We also discuss these effects in the context of the
+multi-channel Kondo impurity model.",0405618v2
+2004-06-29,Pairing gaps in atomic gases at the BCS-BEC crossover,"Strong evidence for pairing and superfluidity has recently been found in
+atomic Fermi gases at the BCS-BEC crossover both in collective modes and RF
+excitation energies. It is argued that the scale for the effective pairing gaps
+measured in RF experiments is set by the lowest quasiparticle in-gap excitation
+energies. These are calculated at the BCS-BEC crossover from semiclassical
+solutions to the Bogoliubov-deGennes equations. The strong damping of the
+radial breathing mode observed in the BCS limit occur when the lowest
+quasiparticle excitation energies coincide with the radial frequency, which
+indicates that a coupling between them take place.",0406714v3
+2004-08-26,Decoherence of Rabi oscillations in a single quantum dot,"We develop a realistic model of Rabi oscillations in a quantum-dot
+photodiode. Based in a multi-exciton density matrix formulation we show that
+for short pulses the two-level models fails and higher levels should be taken
+into account. This affects some of the experimental conclusions, such as the
+inferred efficiency of the state rotation (population inversion) and the
+deduced value of the dipole interaction. We also show that the damping observed
+cannot be explained using \emph{constant} rates with fixed pulse duration. We
+demonstrate that the damping observed is in fact induced by an off-resonant
+excitation to or from the continuum of wetting layer states. Our model
+describes the nonlinear decoherence behavior observed in recent experiments.",0408570v2
+2004-08-28,Breakdown of Hydrodynamics in the Radial Breathing Mode of a Strongly-Interacting Fermi Gas,"We measure the magnetic field dependence of the frequency and damping time
+for the radial breathing mode of an optically trapped, Fermi gas of $^6$Li
+atoms near a Feshbach resonance. The measurements address the apparent
+discrepancy between the results of Kinast et al., [Phys. Rev. Lett. {\bf 92},
+150402 (2004)] and those of Bartenstein et al., [Phys. Rev. Lett. {\bf 92},
+203201 (2004)]. Over the range of magnetic field from 770 G to 910 G, the
+measurements confirm the results of Kinast et al. Close to resonance, the
+measured frequencies are in excellent agreement with predictions for a unitary
+hydrodynamic gas. At a field of 925 G, the measured frequency begins to
+decrease below predictions. For fields near 1080 G, we observe a breakdown of
+hydrodynamic behavior, which is manifested by a sharp increase in frequency and
+damping rate. The observed breakdown is in qualitative agreement with the sharp
+transition observed by Bartenstein et al., at 910 G.",0408634v2
+2004-10-01,Magnetic Properties of Cuprate Perovskites,"The magnetic susceptibility of underdoped yttrium and lanthanum cuprates is
+interpreted based on the self-consistent solution of the t-J model of a Cu-O
+plane. The calculations reproduce correctly the frequency dependencies of the
+susceptibility in YBa2Cu3O_{7-y} and La_{2-x}Sr_xCuO4 attributing their
+dissimilarity to the difference in the damping of spin excitations. In
+YBa2Cu3O_{7-y} these excitations are well defined at the antiferromagnetic wave
+vector Q=(\pi,\pi) even in the normal state which manifests itself in a
+pronounced maximum -- the resonance peak -- in the susceptibility. In
+La_{2-x}Sr_xCuO4 the spin excitations are overdamped which leads to a broad
+low-frequency feature in the susceptibility. The low-frequency
+incommensurability in the magnetic response is attributed to a dip in the
+magnon damping at Q. The calculated concentration and temperature dependencies
+of the incommensurability parameter conform with experimental observations.
+Generally the incommensurate magnetic response is not accompanied with an
+inhomogeneity of the carrier density.",0410009v1
+2004-11-12,Microwave induced resistance oscillations on a high-mobility 2DEG: absorption/reflection and temperature damping experiments,"In this work we address experimentally a number of unresolved issues related
+to microwave induced resistance oscillations (MIRO) and the zero-resistance
+states observed recently on very high-mobility 2D electron gases in GaAs/AlGaAs
+heterostructures. In particular, we examine electrodynamic effects via
+reflection/absorption experiments and study the exact waveform of MIRO and
+their damping due to temperature. It is shown that electrodynamic effects due
+to metallic-like reflection and plasmons are important producing a wide
+cyclotron resonance line and a number of oscillations which do not coincide
+with the MIRO. To describe the MIRO waveform a simple model was employed
+involving radiation-induced scattering with displacement. A very good
+correlation was found between the temperature dependencies of the quantum
+lifetime from MIRO and the transport scattering time from the electron
+mobility. The results are compared with measurements of Shubnikov-de Haas
+oscillations down to 30 mK on the same sample.",0411338v1
+2004-11-17,Path integral derivation of Bloch-Redfield equations for a qubit weakly coupled to a heat bath: Application to nonadiabatic transitions,"Quantum information processing has greatly increased interest in the
+phenomenon of environmentally-induced decoherence. The spin boson model is
+widely used to study the interaction between a spin-modelling a quantum
+particle moving in a double well potential-and its environment-modelled by a
+heat bath of harmonic oscillators. This paper extends a previous analysis of
+the static spin boson study to the driven spin boson case, with the derivation
+of an exact integro-differential equation for the time evolution of the
+propagator of the reduced spin density matrix. This is the first main result.
+By specializing to weak damping we then obtain the next result, a set of
+Bloch-Redfield equations for the equilibrium fixed spin initial condition.
+Finally we show that these equations can be used to solve the classic
+dissipative Landau-Zener problem and illustrate these solutions for the weak
+damping case. The effect of dissipation is seen to be minimised as the speed of
+passage is increased, implying that qubits need to be switched as fast as
+possible.",0411443v1
+2004-11-24,Josephson tunnel junctions with nonlinear damping for RSFQ-qubit circuit applications,"We demonstrate that shunting of Superconductor-Insulator-Superconductor
+Josephson junctions by Superconductor-Insulator-Normal metal (S-I-N) structures
+having pronounced non-linear I-V characteristics can remarkably modify the
+Josephson dynamics. In the regime of Josephson generation the phase behaves as
+an overdamped coordinate, while in the superconducting state the damping and
+current noise are strikingly small, that is vitally important for application
+of such junctions for readout and control of Josephson qubits. Superconducting
+Nb/AlO${_x}$/Nb junction shunted by Nb/AlO${_x}$/AuPd junction of S-I-N type
+was fabricated and, in agreement with our model, exhibited non-hysteretic I-V
+characteristics at temperatures down to at least 1.4 K.",0411607v1
+2004-12-01,"Reply to Millis et al. on ""A Tale of Two Theories: Quantum Griffiths Effects in Metallic Systems""","In a recent paper (cond-mat/0411197) we showed the equivalence of two
+seemingly contradictory theories on Griffiths-McCoy singularities (GMS) in
+metallic antiferromagnets close to a quantum critical point (QCP). In a recent
+comment, Millis {\it et al.} (cond-mat/0411738) argue that in heavy-fermion
+materials the electronic damping is large leading to the freezing of locally
+magnetically ordered droplets at high temperatures. In this reply we show that
+this erroneous conclusion is based on a treatment of the problem of disorder
+close to a QCP which is not self-consistent. We argue that a self-consistent
+treatment of the ordered droplets must lead to weak damping and to a large
+region of GMS behavior, in agreement with the our ealier results.",0412020v2
+2005-01-04,On continuum modeling of sputter erosion under normal incidence: interplay between nonlocality and nonlinearity,"Under specific experimental circumstances, sputter erosion on semiconductor
+materials exhibits highly ordered hexagonal dot-like nanostructures. In a
+recent attempt to theoretically understand this pattern forming process, Facsko
+et al. [Phys. Rev. B 69, 153412 (2004)] suggested a nonlocal, damped
+Kuramoto-Sivashinsky equation as a potential candidate for an adequate
+continuum model of this self-organizing process. In this study we theoretically
+investigate this proposal by (i) formally deriving such a nonlocal equation as
+minimal model from balance considerations, (ii) showing that it can be exactly
+mapped to a local, damped Kuramoto-Sivashinsky equation, and (iii) inspecting
+the consequences of the resulting non-stationary erosion dynamics.",0501049v2
+2005-01-18,Incommensurate spin dynamics in underdoped cuprate perovskites,"The incommensurate magnetic response observed in normal-state cuprate
+perovskites is interpreted based on the projection operator formalism and the
+t-J model of Cu-O planes. In agreement with experiment the calculated
+dispersion of maxima in the susceptibility has the shape of two parabolas with
+upward and downward branches which converge at the antiferromagnetic wave
+vector. The maxima are located at the momenta $({1/2},{1/2}\pm\delta)$,
+$({1/2}\pm\delta,{1/2})$ and at $({1/2}\pm\delta,{1/2}\pm\delta)$,
+$({1/2}\pm\delta,{1/2}\mp\delta)$ in the lower and upper parabolas,
+respectively. The upper parabola reflects the dispersion of magnetic
+excitations of the localized Cu spins, while the lower parabola arises due to a
+dip in the spin-excitation damping at the antiferromagnetic wave vector. For
+moderate doping this dip stems from the weakness of the interaction between the
+spin excitations and holes near the hot spots. The frequency dependence of the
+susceptibility is shown to depend strongly on the hole bandwidth and damping
+and varies from the shape observed in YBa$_2$Cu$_3$O$_{7-y}$ to that inherent
+in La$_{2-x}$Sr$_x$CuO$_4$.",0501418v1
+2005-02-21,Velocity dependence of atomic-scale friction: a comparative study of the one- and two-dimensional Tomlinson model,"We present a comparative analysis of the velocity dependence of atomic-scale
+friction for the Tomlinson model, at zero and finite temperatures, in 1D and
+2D, and for different values of the damping. Combining analytical arguments
+with numerical simulations, we show that an appreciable velocity dependence of
+the kinetic friction force $F_{fric}$, for small scanning velocities $v_s$
+(from 1 nm/s to 2 $\mu$m/s), is inherent in the Tomlinson model. In the absence
+of thermal fluctuations in the stick-slip regime, it has the form of a
+power-law, $F_{fric}-F_0\propto v_s^{\beta}$ with $\beta=2/3$, irrespective of
+dimensionality and value of the damping. Since thermal fluctuations enhance the
+velocity dependence of friction, we provide guidelines to establish when
+thermal effects are important and to which extent the surface corrugation
+affects the velocity dependence.",0502496v1
+2005-03-12,Collective Oscillations of Strongly Correlated One-Dimensional Bosons on a Lattice,"We study the dipole oscillations of strongly correlated 1D bosons, in the
+hard-core limit, on a lattice, by an exact numerical approach. We show that far
+from the regime where a Mott insulator appears in the system, damping is always
+present and increases for larger initial displacements of the trap, causing
+dramatic changes in the momentum distribution, $n_k$. When a Mott insulator
+sets in the middle of the trap, the center of mass barely moves after an
+initial displacement, and $n_k$ remains very similar to the one in the ground
+state. We also study changes introduced by the damping in the natural orbital
+occupations, and the revival of the center of mass oscillations after long
+times.",0503302v2
+2005-04-28,Coherence properties of bulk matter,"We prove a theorem, using the density functional approach and relying on a
+classical result by Lieb and Simon on Thomas-Fermi model, showing that in the
+thermodynamic limit bulk matter is at most semiclassical and coherence
+preserving. The connection between quantum fluid dynamics and density
+functional theory in the formulation due to Kohn and Sham play a significant
+role leading to a Vlasov-Poisson system of equations for the Wigner function.
+Coherence stability is achieved by noting that small oscillations in bulk
+matter are damped by Landau damping. In some conditions the initial Wigner
+function could generate an opposite effect and coherence stability can be lost
+involving higher order quantum effects for a macroscopic body.",0504768v3
+2005-05-19,Harmonic Content of Strain-induced Potential Modulation in Unidirectional Lateral Superlattices,"Detailed analysis of the commensurability oscillation (CO) has been performed
+on unidirectional lateral superlattices with periods ranging from a=92 to 184
+nm. Fourier analysis reveals the second (and the third) harmonics along with
+the fundamental oscillation for a>=138 nm (184 nm) at low-enough temperature,
+evincing the presence of corresponding harmonics in the profile of the
+potential modulation. The harmonics manifest themselves in CO with demagnified
+amplitude due to the low-pass filtering action of the thermal damping factor;
+with a suitable consideration of the damping effect, the harmonics of the
+modulation potential are found to have the amplitudes V_2 and V_3 up to roughly
+30% of that of the fundamental component V_1, despite the small ratio of the
+period a to the depth d = 99 nm of the two-dimensional electron gas (2DEG) from
+the surface. The dependence of V_n on a indicates that the fundamental
+component originates at the surface, while the higher harmonics arise from the
+effect of the strain that penetrates down into subsurface. The manipulation of
+high harmonics thus provides a useful technique to introduce small length-scale
+modulation into high-mobility 2DEGs located deep inside the wafer.",0505479v1
+2005-06-14,Lifetime of the first and second collective excitations in metallic nanoparticles,"We determine the lifetime of the surface plasmon in metallic nanoparticles
+under various conditions, concentrating on the Landau damping, which is the
+dominant mechanism for intermediate-size particles. Besides the main
+contribution to the lifetime, which smoothly increases with the size of the
+particle, our semiclassical evaluation yields an additional oscillating
+component. For the case of noble metal particles embedded in a dielectric
+medium, it is crucial to consider the details of the electronic confinement; we
+show that in this case the lifetime is determined by the shape of the
+self-consistent potential near the surface. Strong enough perturbations may
+lead to the second collective excitation of the electronic system. We study its
+lifetime, which is limited by two decay channels: Landau damping and
+ionization. We determine the size dependence of both contributions and show
+that the second collective excitation remains as a well defined resonance.",0506320v2
+2005-07-27,Dynamics of a nanomechanical resonator coupled to a superconducting single-electron transistor,"We present an analysis of the dynamics of a nanomechanical resonator coupled
+to a superconducting single electron transistor (SSET) in the vicinity of the
+Josephson quasiparticle (JQP) and double Josephson quasiparticle (DJQP)
+resonances. For weak coupling and wide separation of dynamical timescales, we
+find that for either superconducting resonance the dynamics of the resonator is
+given by a Fokker-Planck equation, i.e., the SSET behaves effectively as an
+equilibrium heat bath, characterised by an effective temperature, which also
+damps the resonator and renormalizes its frequency. Depending on the gate and
+drain-source voltage bias points with respect to the superconducting resonance,
+the SSET can also give rise to an instability in the mechanical resonator
+marked by negative damping and temperature within the appropriate Fokker-Planck
+equation. Furthermore, sufficiently close to a resonance, we find that the
+Fokker-Planck description breaks down. We also point out that there is a close
+analogy between coupling a nanomechanical resonator to a SSET in the vicinity
+of the JQP resonance and Doppler cooling of atoms by means of lasers.",0507645v1
+2005-08-01,Unexpected Effect of Internal Degrees of Freedom on Transverse Phonons in Supercooled Liquids,"We show experimentally that in a supercooled liquid composed of molecules
+with internal degrees of freedom the internal modes contribute to the frequency
+dependent shear viscosity and damping of transverse phonons, which results in
+an additional broadening of the transverse Brillouin lines. Earlier, only the
+effect of internal modes on the frequency dependent bulk viscosity and damping
+of longitudinal phonons was observed and explained theoretically in the limit
+of weak coupling of internal degrees of freedom to translational motion. A new
+theory is needed to describe this new effect. We also demonstrate, that the
+contributions of structural relaxation and internal processes to the width of
+the Brillouin lines can be separated by measurements under high pressure.",0508046v1
+2005-08-08,Collective excitations of low density fermion-boson quantum-liquid mixtures,"We investigate the collective excitations of a low temperature dilute gas
+mixture that consists of a Bose-Einstein condensate and a Fermi-gas that is a
+normal (i.e. non-superfluid) Fermi-liquid. We find that the BEC-mediated
+fermion-fermion interactions, as a consequence of retardation, can become
+repulsive and support a zero-sound mode that is essentially undamped. In
+addition, we find a damped zero-sound mode that can be described as a BEC-sound
+mode modified by fermion mediated boson-boson interactions, and we derive its
+decay-rate caused by Landau damping. We study the mode structure of these
+excitations and find avoided crossing behavior as well as a termination point.
+The collective mode dynamics also reveals that phase separation sets in when
+the fermion-mediated boson-boson interaction destroys the stability of the
+homogeneous BEC. We estimate the time and length scales of the onset of the
+phase separation, and we discuss the feasibility of experimentally probing
+these consequences of mediated interactions.",0508207v1
+2005-10-26,Multiple electron-hole scattering effect on quasiparticle properties in a homogeneous electron gas,"We present a detailed study of a contribution of the T matrix accounting for
+multiple scattering between an electron and a hole to the quasiparticle
+self-energy. This contribution is considered as an additional term to the GW
+self-energy. The study is based on a variational solution of the T-matrix
+integral equation within a local approximation. A key quantity of such a
+solution, the local electron-hole interaction, is obtained at the small
+four-momentum transfer limit. Performed by making use of this limit form,
+extensive calculations of quasiparticle properties in the homogeneous electron
+gas over a broad range of electron densities are reported. We carry out an
+analysis of how the T-matrix contribution affects the quasiparticle damping
+rate, the quasiparticle energy, the renormalization constant, and the effective
+mass enhancement. We find that in comparison with the GW approximation the
+inclusion of the T matrix leads to an essential increase of the damping rate, a
+slight reduction of the GW band narrowing, a decrease of the renormalization
+constant at the Fermi wave vector, and some ""weighting"" of quasiparticles at
+the Fermi surface.",0510684v2
+2005-10-27,Acoustic damping in Li$_2$O-2B$_2$O$_3$ glass observed by inelastic x-ray and optical Brillouin scattering,"The dynamic structure factor of lithium-diborate glass has been measured at
+several values of the momentum transfer $Q$ using high resolution inelastic
+x-ray scattering. Much attention has been devoted to the low $Q$-range, below
+the observed Ioffe-Regel crossover \qco{}$\simeq$ 2.1 nm$^{-1}$. We find that
+below \qco{}, the linewidth of longitudinal acoustic waves increases with a
+high power of either $Q$, or of the frequency $\Omega$, up to the crossover
+frequency \OMco{} $\simeq$ 9 meV that nearly coincides with the center of the
+boson peak. This new finding strongly supports the view that resonance and
+hybridization of acoustic waves with a distribution of rather local low
+frequency modes forming the boson peak is responsible for the end of acoustic
+branches in strong glasses. Further, we present high resolution Brillouin
+light-scattering data obtained at much lower frequencies on the same sample.
+These clearly rule out a simple $\Omega^2$-dependence of the acoustic damping
+over the entire frequency range.",0510714v1
+2005-12-07,Acoustic attenuation probe for fermion superfluidity in ultracold atom gases,"Dilute gas Bose-Einstein condensates (BEC's), currently used to cool
+fermionic atoms in atom traps, can also probe the superfluidity of these
+fermions. The damping rate of BEC-acoustic excitations (phonon modes), measured
+in the middle of the trap as a function of the phonon momentum, yields an
+unambiguous signature of BCS-like superfluidity, provides a measurement of the
+superfluid gap parameter and gives an estimate of the size of the Cooper-pairs
+in the BEC-BCS crossover regime. We also predict kinks in the momentum
+dependence of the damping rate which can reveal detailed information about the
+fermion quasi-particle dispersion relation.",0512134v4
+2006-01-11,"Apparent phonon side band modes in pi-conjugated systems: polymers, oligomers and crystals","The emission spectra of many pi-conjugated polymers and oligomers contain
+side-band replicas with apparent frequencies that do not match the Raman active
+mode frequencies. Using a time dependent model we show that in such many mode
+systems, the increased damping of the time dependent transition dipole moment
+correlation function results in an effective elimination of the vibrational
+modes from the emission spectrum; subsequently causing the appearance of a
+regularly spaced progression at a new apparent frequency. We use this damping
+dependent vibrational reshaping to quantitatively account for the vibronic
+structure in the emission spectra of pi-conjugated systems in the form of
+films, dilute solutions and single crystals. In particular, we show that by
+using the experimentally measured Raman spectrum we can account in detail for
+the apparent progression frequencies and their relative intensities in the
+emission spectrum.",0601218v1
+2006-03-01,Renormalization of the electron-spin-fluctuation interaction in the t-t'-U Hubbard model,"We study the renormalization of the electron-spin-fluctuation (el-sp) vertex
+in a two-dimensional Hubbard model with nearest-neighbor (t) and
+next-nearest-neighbor (t') hopping by a Quantum-Monte-Carlo calculation. Our
+results show that for t'=0, the renormalized el-sp vertex decreases quite
+generally with decreasing temperature at all spin-fluctuation momentum
+transfers. The suppression of the el-sp vertex results in a substantial
+reduction of the effective pairing interaction mediated by antiferromagnetic
+spin fluctuations in both the intermediate- and strong-correlation regimes. The
+inclusion of a finite t'/t<0, increases the Landau damping rate of spin
+fluctuations, especially in the overdoped region. The increased damping rate
+leads to smaller vertex corrections, in agreement with earlier diagrammatic
+calculations. Still, the vertex correction reduces the spin-fermion vertex, as
+at t'=0.",0603014v3
+2006-07-18,Equilibrium and non-equilibrium dynamics of the sub-ohmic spin-boson model,"Employing the non-perturbative numerical renormalization group method, we
+study the dynamics of the spin-boson model, which describes a two-level system
+coupled to a bosonic bath with spectral density J(omega) propto omega^s. We
+show that, in contrast to the case of ohmic damping, the delocalized phase of
+the sub-ohmic model cannot be characterized by a single energy scale only, due
+to the presence of a non-trivial quantum phase transition. In the strongly
+sub-ohmic regime, s<<1, weakly damped coherent oscillations on short time
+scales are possible even in the localized phase - this is of crucial relevance,
+e.g., for qubits subject to electromagnetic noise.",0607443v2
+2006-09-29,Quantum master equation for electron transport through quantum dots and single molecules,"A quantum master equation (QME) is derived for the many-body density matrix
+of an open current-carrying system weakly coupled to two metal leads. The
+dynamics and the steady-state properties of the system for arbitrary bias are
+studied using projection operator techniques, which keep track of number of
+electrons in the system. We show that coherences between system states with
+different number of electrons, n, (Fock space coherences) do not contribute to
+the transport to second order in system-lead coupling.
+  However, coherences between states with the same n may effect transport
+properties when the damping rate is of the order or faster then the system Bohr
+frequencies.
+  For large bias, when all the system many-body states lie between the chemical
+potentials of the two leads, we recover previous results. In the rotating wave
+approximation (when the damping is slow compared to the Bohr frequencies of the
+system), the dynamics of populations and the coherences in the system
+eigenbasis are decoupled. The QME then reduces to a birth and death master
+equation for populations.",0610004v1
+2006-10-25,Pulse and hold strategy for switching current measurements,"We investigate by theory and experiment, the Josephson junction switching
+current detector in an environment with frequency dependent damping. Analysis
+of the circuit's phase space show that a favorable topology for switching can
+be obtained with overdamped dynamics at high frequencies. A pulse-and-hold
+method is described, where a fast switch pulse brings the circuit close to an
+unstable point in the phase space when biased at the hold level. Experiments
+are performed on Cooper pair transistors and Quantronium circuits, which are
+overdamped at high frequencies with an on-chip RC shunt. For 20 us switch
+pulses the switching process is well described by thermal equilibrium escape,
+based on a generalization of Kramers formula to the case of frequency dependent
+damping. A capacitor bias method is used to create very rapid, 25 ns switch
+pulses, where it is observed that the switching process is not governed by
+thermal equilibrium noise.",0610704v2
+2006-10-29,Experimental Studies of Low-field Landau Quantization in Two-dimensional Electron Systems in GaAs/AlGaAs Heterostructures,"By applying a magnetic field perpendicular to GaAs/AlGaAs two-dimensional
+electron systems, we study the low-field Landau quantization when the thermal
+damping is reduced with decreasing the temperature. Magneto-oscillations
+following Shubnikov-de Haas (SdH) formula are observed even when their
+amplitudes are so large that the deviation to such a formula is expected. Our
+experimental results show the importance of the positive magneto-resistance to
+the extension of SdH formula under the damping induced by the disorder.",0610805v1
+2006-11-18,Distributions of switching times of single-domain particles using a time quantified Monte Carlo method,"Using a time quantified Monte Carlo scheme we performed simulations of the
+switching time distribution of single mono-domain particles in the
+Stoner-Wohlfarth approximation. We considered uniaxial anisotropy and different
+conditions for the external applied field. The results obtained show the
+switching time distribution can be well described by two relaxation times,
+either when the applied field is parallel to the easy axis or for an oblique
+external field and a larger damping constant. We found that in the low barrier
+limit these relaxation times are in very good agreement with analytical results
+obtained from solutions of the Fokker-Planck equation related to this problem.
+When the damping is small and the applied field is oblique the shape of the
+distribution curves shows several peaks and resonance effects.",0611494v2
+2007-01-12,Electron spin quantum beats in positively charged quantum dots: nuclear field effects,"We have studied the electron spin coherence in an ensemble of positively
+charged InAs/GaAs quantum dots. In a transverse magnetic field, we show that
+two main contributions must be taken into account to explain the damping of the
+circular polarization oscillations. The first one is due to the nuclear field
+fluctuations from dot to dot experienced by the electron spin. The second one
+is due to the dispersion of the transverse electron Lande g-factor, due to the
+inherent inhomogeneity of the system, and leads to a field dependent
+contribution to the damping. We have developed a model taking into account both
+contributions, which is in good agreement with the experimental data. This
+enables us to extract the pure contribution to dephasing due to the nuclei.",0701284v2
+2007-02-05,Verification of stable operation of rapid single flux quantum devices with selective dissipation,"It has been suggested that Rapid Single Flux Quantum (RSFQ) devices could be
+used as the classical interface of superconducting qubit systems. One problem
+is that the interface acts as a dissipative environment for a qubit. Recently
+ways to modify the RSFQ damping to reduce the dissipation have been introduced.
+One of the solutions is to damp the Josephson junctions by a
+frequency-dependent linear circuit instead of the plain resistor. The approach
+has previously been experimentally tested with a simple SFQ comparator. In this
+paper we perform experiments with a full RSFQ circuit, and thus conclude that
+in terms of stable operation the approach is applicable for scalable RSFQ
+circuits. Realisation and optimisation issues are also discussed.",0702104v1
+2007-02-21,RPAE versus RPA for the Tomonaga model with quadratic energy dispersion,"Recently the damping of the collective charge (and spin) modes of interacting
+fermions in one spatial dimension was studied. It results from the nonlinear
+correction to the energy dispersion in the vicinity of the Fermi points. To
+investigate the damping one has to replace the random phase approximation (RPA)
+bare bubble by a sum of more complicated diagrams. It is shown here that a
+better starting point than the bare RPA is to use the (conserving) linearized
+time dependent Hartree-Fock equations, i.e. to perform a random phase
+approximation (with) exchange
+  (RPAE) calculation. It is shown that the RPAE equation can be solved
+analytically for the special form of the two-body interaction often used in the
+Luttinger liquid framework. While (bare) RPA and RPAE agree for the case of a
+strictly linear disperson there are qualitative differences for the case of the
+usual nonrelativistic quadratic dispersion.",0702488v2
+2007-03-01,Spin dynamics across the superfluid-insulator transition of spinful bosons,"Bosons with non-zero spin exhibit a rich variety of superfluid and insulating
+phases. Most phases support coherent spin oscillations, which have been the
+focus of numerous recent experiments. These spin oscillations are Rabi
+oscillations between discrete levels deep in the insulator, while deep in the
+superfluid they can be oscillations in the orientation of a spinful condensate.
+We describe the evolution of spin oscillations across the superfluid-insulator
+quantum phase transition. For transitions with an order parameter carrying
+spin, the damping of such oscillations is determined by the scaling dimension
+of the composite spin operator. For transitions with a spinless order parameter
+and gapped spin excitations, we demonstrate that the damping is determined by
+an associated quantum impurity problem of a localized spin excitation
+interacting with the bulk critical modes. We present a renormalization group
+analysis of the quantum impurity problem, and discuss the relationship of our
+results to experiments on ultracold atoms in optical lattices.",0703011v2
+2007-03-21,Edge magnetoplasmons in a partially screened two-dimensional electron gas on a helium surface,"We report a study of edge magnetoplasmons in a partially-screened system of
+electrons on a helium surface. We compare experimental results with theories of
+the frequency, damping, and penetration-depth dependence on magnetic field,
+temperature-dependent damping, and the dependence of the frequency on
+screening. We show explicitly the dependence of frequency on the edge density
+profile. The frequency and screening are in qualitative agreement with the
+theory of Fetter at small fields, and the frequencies agree with theory in the
+limit of zero magnetic field. The frequency and linewidths in intermediate and
+large fields exhibit the features of the qualitative predictions of Volkov and
+Mikhailov, but differ numerically. Deviations from theory for a finite sample
+occur at smaller fields. The dependence of frequency on the density profile is
+stronger than predicted by these authors, and the penetration-depth variation
+with field confirms their prediction for small fields.",0703558v1
+1997-02-12,On the problem of semiinfinite beam oscillation with internal damping,"We study the Cauchy problem for the equation of the form $$ \ddot{u}(t) +
+(\aa A + B)\dot{u}(t) + (A+G)u(t) = 0,\tag* $$ where $A$, $B$, and $G$ are \o s
+in a Hilbert space $\Cal H$ with $A$ selfadjoint, $\sigma(A)=[0,\infty)$,
+$B\ge0$ bounded, and $G$ symmetric and $A$-subordinate in a certain sense.
+Spectral properties of the correspondent operator pencil
+  $L(\lambda) := \lambda^2I + \lambda (\alpha A + B) + A + G$ are studied, and
+existence and uniqueness of generalized and classical solutions of the Cauchy
+problem are proved. Equations of the type (*) include, e.g., an abstract model
+for the problem of semiinfinite beam oscillations with internal damping.",9702007v1
+1994-04-14,"Decoherence, Correlation, and Unstable Quantum States in Semiclassical Cosmology","It is demonstrated that almost any S-matrix of quantum field theory in curved
+spaces posses an infinite set of complex poles (or branch cuts). These poles
+can be transformed into complex eigenvalues, the corresponding eigenvectors
+being Gamow vectors. All this formalism, which is heuristic in ordinary Hilbert
+space, becomes a rigorous one within the framework of a properly chosen rigged
+Hilbert space. Then complex eigenvalues produce damping or growing factors. It
+is known that the growth of entropy, decoherence, and the appearance of
+correlations, occur in the universe evolution, but only under a restricted set
+of initial conditions. It is proved that the damping factors allow to enlarge
+this set up to almost any initial conditions.",9404028v1
+1994-09-27,Effects of weak self-interactions in a relativistic plasma on cosmological perturbations,"The exact solutions for linear cosmological perturbations which have been
+obtained for collisionless relativistic matter within thermal field theory are
+extended to a self-interacting case. The two-loop contributions of scalar
+$\lambda\phi^4$ theory to the thermal graviton self-energy are evaluated, which
+give the $O(\lambda)$ corrections in the perturbation equations. The changes
+are found to be perturbative on scales comparable to or larger than the Hubble
+horizon, but the determination of the large-time damping behavior of subhorizon
+perturbations requires a resummation of thermally induced masses.",9409055v2
+1995-03-07,ON THE OSCILLATION SPECTRA OF ULTRA COMPACT STARS,"Quasinormal modes of ultra compact stars with uniform energy density have
+been calculated. For less compact stars, there is only one very slowly damped
+polar mode (corresponding to the Kelvin f-mode) for each spherical harmonic
+index $l$. Further long-lived modes become possible for a sufficiently compact
+star (roughly when $M/R \ge 1/3$). We compare the characteristic frequencies of
+these resonant polar modes to the axial modes first found by Chandrasekhar and
+Ferrari [{\em Proc. Roy. Soc. London A} {\bf 434} 449 (1991)]. We find that the
+two spectra approach each other as the star is made more compact. The
+oscillation frequencies of the corresponding polar and axial modes agree to
+within a percent for stars more compact than $M/R = 0.42$. At the same time,
+the damping times are slightly different. The results illustrate that there is
+no real difference between the origin of these axial and polar modes: They are
+essentially spacetime modes.",9503012v1
+1998-02-13,Radiation Damping in FRW Space-times with Different Topologies,"We study the role played by the compactness and the degree of connectedness
+in the time evolution of the energy of a radiating system in the
+Friedmann-Robertson-Walker (FRW) space-times whose $t=const $ spacelike
+sections are the Euclidean 3-manifold ${\cal R}^3$ and six topologically
+non-equivalent flat orientable compact multiply connected Riemannian
+3-manifolds. An exponential damping of the energy $E(t)$ is present in the
+${\cal R}^3$ case, whereas for the six compact flat 3-spaces it is found
+basically the same pattern for the evolution of the energy, namely relative
+minima and maxima occurring at different times (depending on the degree of
+connectedness) followed by a growth of $E(t)$. Likely reasons for this
+divergent behavior of $E(t)$ in these compact flat 3-manifolds are discussed
+and further developments are indicated. A misinterpretation of Wolf's results
+regarding one of the six orientable compact flat 3-manifolds is also indicated
+and rectified.",9802031v1
+1998-05-06,Damping of Gravitational Waves and Density Perturbations in the Early Universe,"Since the discovery of the large angular scale anisotropies in the microwave
+background radiation, the behaviour of cosmological perturbations (especially,
+density perturbations and gravitational waves) has been of great interest. In
+this study, after a detailed and rigorous treatment of the behaviour of
+gravitational waves in viscous cosmic media, we conclude that the damping of
+cosmological gravitational waves of long wavelengths is negligible for most
+cases of physical interest. A preliminary analysis suggests that similar
+results hold for density perturbations in the long wavelength limit. Therefore,
+long wavelength cosmological perturbations have not been practically affected
+by viscous processes,and are good probes of the very early Universe.",9805016v1
+1998-11-11,Late-Time Evolution of Realistic Rotating Collapse and The No-Hair Theorem,"We study analytically the asymptotic late-time evolution of realistic
+rotating collapse. This is done by considering the asymptotic late-time
+solutions of Teukolsky's master equation, which governs the evolution of
+gravitational, electromagnetic, neutrino and scalar perturbations fields on
+Kerr spacetimes. In accordance with the no-hair conjecture for rotating
+black-holes we show that the asymptotic solutions develop inverse power-law
+tails at the asymptotic regions of timelike infinity, null infinity and along
+the black-hole outer horizon (where the power-law behaviour is multiplied by an
+oscillatory term caused by the dragging of reference frames). The damping
+exponents characterizing the asymptotic solutions at timelike infinity and
+along the black-hole outer horizon are independent of the spin parameter of the
+fields. However, the damping exponents at future null infinity are spin
+dependent. The late-time tails at all the three asymptotic regions are
+spatially dependent on the spin parameter of the field. The rotational dragging
+of reference frames, caused by the rotation of the black-hole (or star) leads
+to an active coupling of different multipoles.",9811032v2
+1999-09-22,Vorticity affects the stability of neutron stars,"The spin rate \Omega of neutron stars at a given temperature T is constrained
+by the interplay between gravitational-radiation instabilities and viscous
+damping. Navier-Stokes theory has been used to calculate the viscous damping
+timescales and produce a stability curve for r-modes in the (\Omega,T) plane.
+In Navier-Stokes theory, viscosity is independent of vorticity, but kinetic
+theory predicts a coupling of vorticity to the shear viscosity. We calculate
+this coupling and show that it can in principle significantly modify the
+stability diagram at lower temperatures. As a result, colder stars can remain
+stable at higher spin rates.",9909073v2
+2000-02-02,Active controls in interferometric detectors of gravitational waves: inertial damping of the VIRGO superattenuator,"The operation of an interferometer for gravitational waves detection requires
+sophisticated feedback controls in many parts of the apparatus. The aim of this
+lecture is to introduce the types of problems to be faced in this line of
+research. The attention is focused on the ""inertial damping"" of the test mass
+suspension of the VIRGO interferometer (the superattenuator): it is a
+multidimensional local control aimed to reduce the residual motion of the
+suspended mirror associated to the normal modes of the suspension. Its
+performance is very important for the locking of the interferometer.",0002006v2
+2000-08-09,Gravitational Wave Damping of Neutron Star Wobble,"We calculate the effect of gravitational wave (gw) back-reaction on realistic
+neutron stars (NS's) undergoing torque-free precession. By `realistic' we mean
+that the NS is treated as a mostly-fluid body with an elastic crust, as opposed
+to a rigid body. We find that gw's damp NS wobble on a timescale tau_{theta}
+approx 2 x 10^5 yr [10^{-7}/(DId/I_0)]^2 (kHz/ nu_s)^4, where nu_s is the spin
+frequency and DId is the piece of the NS's inertia tensor that ""follows"" the
+crust's principal axis (as opposed to its spin axis). We give two different
+derivations of this result: one based solely on energy and angular momentum
+balance, and another obtained by adding the Burke-Thorne radiation reaction
+force to the Newtonian equations of motion. This problem was treated long ago
+by Bertotti and Anile (1973), but their claimed result is wrong. When we
+convert from their notation to ours, we find that their tau_{theta} is too
+short by a factor of order 10^5 for typical cases of interest, and even has the
+wrong sign for DId negative. We show where their calculation went astray.",0008021v1
+2000-11-30,Tests of strong-field gravity and gravitational radiation damping in binary-pulsar systems,"This talk reviews the constraints imposed by binary-pulsar data on gravity
+theories, and notably on ""scalar-tensor"" theories which are the most natural
+alternatives to general relativity. Because neutron stars have a strong
+gravitational binding energy, binary-pulsar tests are qualitatively different
+from solar-system experiments: They have the capability of probing models which
+are indistinguishable from general relativity in weak gravitational field
+conditions. Besides the two most precise binary-pulsar experiments, in the
+systems B1913+16 and B1534+12, we also present the results of the various
+""null"" tests of general relativity provided by several neutron star-white dwarf
+binaries, notably those of gravitational radiation damping. [The main interest
+of this very short paper is its figure, which also takes into account the
+""strong equivalence principle"" tests.]",0011114v1
+2001-07-17,Properties of r modes in rotating magnetic neutron stars. I. Kinematic Secular Effects and Magnetic Evolution Equations,"The instability of r-mode oscillations in rapidly rotating neutron stars has
+attracted attention as a potential mechanism for producing high frequency,
+almost periodic gravitational waves. The analyses carried so far have shown the
+existence of these modes and have considered damping by shear and bulk
+viscosity. However, the magnetohydrodynamic coupling of the modes with a
+stellar magnetic field and its role in the damping of the instability has not
+been fully investigated yet. Following our introductory paper (Rezzolla, Lamb
+and Shapiro 2000), we here discuss in more detail the existence of secular
+higher-order kinematical effects which will produce toroidal fluid drifts. We
+also define the sets of equations that account for the time evolution of the
+magnetic fields produced by these secular velocity fields and show that the
+magnetic fields produced can reach equipartition in less than a year. The full
+numerical calculations as well as the evaluation of the impact of strong
+magnetic fields on the onset and evolution of the r-mode instability will be
+presented in a companion paper.",0107061v1
+2004-01-13,Highly Damped Quasinormal Modes of Kerr Black Holes: A Complete Numerical Investigation,"We compute for the first time very highly damped quasinormal modes of the
+(rotating) Kerr black hole. Our numerical technique is based on a decoupling of
+the radial and angular equations, performed using a large-frequency expansion
+for the angular separation constant_{s}A_{l m}. This allows us to go much
+further in overtone number than ever before. We find that the real part of the
+quasinormal frequencies approaches a non-zero constant value which does not
+depend on the spin s of the perturbing field and on the angular index l:
+\omega_R=m\varpi(a). We numerically compute \varpi(a). Leading-order
+corrections to the asymptotic frequency are likely to be of order 1/\omega_I.
+The imaginary part grows without bound, the spacing between consecutive modes
+being a monotonic function of a.",0401052v1
+2006-12-07,Improved calculation of relic gravitational waves,"In this paper, we improve the calculation of the relic gravitational waves
+(RGW) in two aspects: First, we investigate the transfer function after
+considering the redshift-suppression effect, the accelerating expansion effect,
+the damping effect of free-streaming relativistic particles, and the damping
+effect of cosmic phase transition, and give a simple approximate analytic
+expression, which clearly illustrates the dependent relations on the
+cosmological parameters. Second, we develop a numerical method to calculate the
+primordial power spectrum of RGW at a very wide frequency range, where the
+observed constraints on $n_s$ (the scalar spectral index) and $P_S(k_0)$ (the
+amplitude of primordial scalar spectrum) and the Hamilton-Jacobi equation are
+used. This method is applied to two kinds of inflationary models, which all
+satisfy the current constraints on $n_s$, $\alpha$ (the running of $n_s$) and
+$r$ (the tensor-scalar ratio). We plot them in the $r-\Omega_g$ diagram, where
+$\Omega_g$ is the strength of RGW, and study their detection by the CMB
+experiments and laser interferometers.",0612041v3
+2007-03-29,Constraint Damping in First-Order Evolution Systems for Numerical Relativity,"A new constraint suppressing formulation of the Einstein evolution equations
+is presented, generalizing the five-parameter first-order system due to Kidder,
+Scheel and Teukolsky (KST). The auxiliary fields, introduced to make the KST
+system first-order, are given modified evolution equations designed to drive
+constraint violations toward zero. The algebraic structure of the new system is
+investigated, showing that the modifications preserve the hyperbolicity of the
+fundamental and constraint evolution equations. The evolution of the
+constraints for pertubations of flat spacetime is completely analyzed, and all
+finite-wavelength constraint modes are shown to decay exponentially when
+certain adjustable parameters satisfy appropriate inequalities. Numerical
+simulations of a single Schwarzschild black hole are presented, demonstrating
+the effectiveness of the new constraint-damping modifications.",0703145v1
+1992-06-21,Gauge Dependence of the Resummed Thermal Gluon Self Energy,"The gauge dependence of the hot gluon self energy is examined in the context
+of Pisarski's method for resumming hard thermal loops. Braaten and Pisarski
+have used the Ward identities satisfied by the hard corrections to the n-point
+functions to argue the gauge fixing independence of the leading order resummed
+QCD plasma damping rate in covariant and strict Coulomb gauges. We extend their
+analysis to include all linear gauges that preserve rotational invariance and
+display explicitly the conditions required for gauge fixing independence. It is
+shown that in covariant gauges the resummed damping constant is gauge fixing
+independent only if an infrared regulator is explicitly maintained throughout
+the calculation.",9206239v1
+1993-05-07,Thermal quark production in pure glue and quark gluon plasmas,"We calculate production rates for massless $(u,d)$ and massive $(s,c,b)$
+quarks in pure glue and quark gluon plasmas to leading order in the strong
+coupling constant $g$. The leading contribution comes from gluon decay into
+$q\bar q$ pairs, using a thermal gluon propagator with finite thermal mass and
+damping rate. The rate behaves as $\alpha_S^2(\ln 1/\alpha_S)^2 T^4$ when $m,
+\alpha_S \rightarrow 0$ and depends linearly on the transverse gluon damping
+rate for all values of the quark mass $m$. The light quark ($u$, $d$, $s$)
+chemical equilibration time is approximately 10-100 $T^{-1}$ for $g=$2-3, so
+that quarks are likely to remain far from chemical equilibrium in
+ultrarelativistic nuclear collisions.",9305227v1
+1994-04-20,Electroweak Baryogenesis and Standard Model CP Violation,"We analyze the mechanism of electroweak baryogenesis proposed by Farrar and
+Shaposhnikov in which the phase of the CKM mixing matrix is the only source of
+$CP$ violation. This mechanism is based on a phase separation of baryons via
+the scattering of quasiparticles by the wall of an expanding bubble produced at
+the electroweak phase transition. In agreement with the recent work of Gavela,
+Hern\'andez, Orloff and P\`ene, we conclude that QCD damping effects reduce the
+asymmetry produced to a negligible amount. We interpret the damping as quantum
+decoherence. We compute the asymmetry analytically. Our analysis reflects the
+observation that only a thin, outer layer of the bubble contributes to the
+coherent scattering of the quasiparticles. The generality of our arguments
+rules out any mechanism of electroweak baryogenesis that does not make use of a
+new source of $CP$ violation.",9404302v1
+1994-06-11,Standard Model CP-violation and Baryon asymmetry Part II: Finite Temperature,"We consider the scattering of quasi-particles off the boundary created during
+a first order electroweak phase transition. Spatial coherence is lost due to
+the quasi-quark damping rate, and we show that reflection on the boundary is
+suppressed, even at tree-level. Simply on CP considerations, we argue against
+electroweak baryogenesis in the Standard Model via the charge transport
+mechanism. A CP asymmetry is produced in the reflection properties of quarks
+and antiquarks hitting the phase boundary. An effect is present at order
+$\alpha_W^2$ in rate and a regular GIM behaviour is found, which can be
+expressed in terms of two unitarity triangles. A crucial role is played by the
+damping rate of quasi-particles in a hot plasma, which is a relevant scale
+together with $M_W$ and the temperature. The effect is many orders of magnitude
+below what observation requires.",9406289v2
+1995-01-03,High temperature QCD and QED with unstable excitations,"We consider the partition functions of QCD and QED at high temperature
+assuming small coupling constants, and present arguments in favor of an
+improved perturbative expansion in terms of unstable excitations. Our effective
+propagators are derived from spectral functions with a constant width. These
+spectral functions describe screening and damping of gluons (photons) as well
+as ``Brownian'' motion of quarks (electrons). BRST-invariance allows us to
+reduce the number of independent width parameters to three. These are
+determined in a self-consistent way from the one-loop self energy and
+polarization tensor in the infrared limit thus rendering this limit finite. All
+spectral width parameters are found to be proportional to $g T$. We reproduce
+the well known expression for the electric ``Debye''-screening mass. The
+transverse (magnetic) gluons (photons) are found to interact only at nonzero
+momentum or energy, at least to leading order. As a consequence their spectral
+function acquires a width only away from the infrared limit. Finally, plasmon
+modes are determined and found to be strongly damped.",9501203v1
+1995-12-12,Bubble Collisions and Defect Formation in a Damping Environment,"Within the context of a first-order phase transition in the early Universe,
+we study the collision process for vacuum bubbles expanding in a plasma. The
+effects of the plasma are simulated by introducing a damping term in the
+equations of motion for a $U(1)$ global field. We find that Lorentz-contracted
+spherically symmetric domain walls adequately describe the overdamped motion of
+the bubbles in the thin wall approximation, and study the process of collision
+and phase equilibration both numerically and analytically. With an analytical
+model for the phase propagation in 1+1 dimensions, we prove that the phase
+waves generated in the bubble merging are reflected by the walls of the true
+vacuum cavity, giving rise to a long-lived oscillating state that delays the
+phase equilibration. The existence of such a state in the 3+1 dimensional model
+is then confirmed by numerical simulations, and the consequences for the
+formation of vortices in three-bubble collisions are considered.",9512290v1
+1996-09-02,The quasiparticle structure of hot gauge theories,"The study of the ultrarelativistic plasmas in perturbation theory is plagued
+with infrared divergences which are not eliminated by the screening
+corrections. They affect, in particular, the computation of the lifetime of the
+elementary excitations, thus casting doubt on the validity of the quasiparticle
+picture. We show that, for Abelian plasmas at least, the infrared problem of
+the damping rate can be solved by a non-perturbative treatment based on the
+Bloch-Nordsieck approximation. The resulting expression of the fermion
+propagator is free of divergences, and exhibits a {\it non-exponential} damping
+at large times: $S_R(t)\sim \exp\{-\alpha T t \ln\omega_pt\}$, where
+$\omega_p=gT/3$ is the plasma frequency and $\alpha=g^2/4\pi$.",9609225v1
+1996-10-18,Finiteness of Hot Classical Scalar Field Theory and the Plasmon Damping Rate,"We investigate the renormalizability of the classical $\phi^4$ theory at
+finite temperature. We calculate the time-dependent two point function to two
+loop order and show that it can be rendered finite by the counterterms of the
+classical static theory. As an application the classical plasmon damping rate
+is found to be $\gamma = \lambda^2 T^2/1536 \pi m$. When we use the high
+temperature expression for $m$ given by dimensional reduction, the rate is
+found to agree with the quantum mechanical result.",9610415v2
+1996-12-30,Defect Formation in First Order Phase Transitions with Damping,"Within the context of first order phase transitions in the early universe, we
+study the influence of a coupling between the (global U(1)) scalar driving the
+transition and the rest of the matter content of the theory. The effect of the
+coupling on the scalar is simulated by introducing a damping term in its
+equations of motion, as suggested by recent results in the electroweak phase
+transition. After a preceeding paper, in which we studied the influence that
+this coupling has in the dynamics of bubble collisions and topological defect
+formation, we proceed in this paper to quantify the impact of this new effects
+on the probability of defect creation per nucleating bubble.",9612487v1
+1997-07-28,Plasmon properties in classical lattice gauge theory,"In order to investigate the features of the classical approximation at high
+temperatures for real time correlation functions, the plasmon frequencies and
+damping rates were recently computed numerically in the SU(2)+Higgs model and
+in the pure SU(2) theory. We compare the lattice results with leading order
+hard thermal loop resummed perturbation theory. In the broken phase of the
+SU(2)+Higgs model, we show that the lattice results can be reproduced and that
+the lattices used are too coarse to observe some important plasmon effects. In
+the symmetric phase, the main qualitative features of the lattice results can
+also be understood. In the pure SU(2) theory, on the other hand, there are
+discrepancies which might point to larger Landau and plasmon damping effects
+than indicated by perturbation theory.",9707489v2
+1998-09-11,Dynamical renormalization group resummation of finite temperature infrared divergences,"We introduce the method of dynamical renormalization group to study
+relaxation and damping out of equilibrium directly in real time and applied it
+to the study of infrared divergences in scalar QED. This method allows a
+consistent resummation of infrared effects associated with the exchange of
+quasistatic transverse photons and leads to anomalous logarithmic relaxation of
+the form $e^{-\alpha T t \ln[t/t_0]}$ which prevents a quasiparticle
+interpretation of charged collective excitations at finite temperature. The
+hard thermal loop resummation program is incorporated consistently into the
+dynamical renormalization group yielding a picture of relaxation and damping
+phenomena in a plasma in real time that trascends the conceptual limitations of
+the quasiparticle picture and other type of resummation schemes. We derive a
+simple criterion for establishing the validity of the quasiparticle picture to
+lowest order.",9809346v2
+1999-02-12,Beyond HTL: The Classical Kinetic Theory of Landau Damping for Selfinteracting Scalar Fields in the Broken Phase,"The effective theory of low frequency fluctuations of selfinteracting scalar
+fields is constructed in the broken symmetry phase. The theory resulting from
+integrating fluctuations with frequencies much above the spontanously generated
+mass scale $(p_0>>M)$ is found to be local. Non-local dynamics, especially
+Landau damping emerges under the effect of fluctuations in the $p_0 \sim M$
+region. A kinetic theory of relativistic scalar gas particles interacting via
+their locally variable mass with the low frequency scalar field is shown to be
+equivalent to this effective field theory for scales below the characteristic
+mass, that is beyond the accuracy of the Hard Thermal Loop (HTL) approximation.",9902331v1
+2000-04-05,A consistent nonperturbative approach to thermal damping-rates,"We propose a nonperturbative scheme for the calculation of thermal
+damping-rates using exact renormalization group (RG)-equations. Special
+emphasis is put on the thermal RG where first results for the rate were given
+in M. Pietroni, Phys. Rev. Lett. 81 (1998), 2424. We point out that in order to
+obtain a complete result that also reproduces the known perturbative behaviour
+one has to take into account effects that were neglected in the work cited
+above. We propose a well-defined way of doing the calculations that reproduces
+perturbation theory in lowest order but goes considerably beyond perturbative
+results and should be applicable also at second order phase-transitions.",0004039v2
+2000-06-09,Random values of the cosmological constant,"One way that an anthropic selection mechanism may be manifest in a physical
+theory involves multiple domains in the universe with different values of the
+physical parameters. If this mechanism is to be relevant for understanding the
+small observed value of the cosmological constant, it may involve a mechanism
+by which some contributions to the cosmological constant can be fixed at a
+continuous range of values in the different domains. I study the properties of
+four possible mechanisms, including the possibility of the Hubble damping of a
+scalar field with an extremely flat potential. Another interesting possibility
+involves fixed random values of non-dynamical form fields, and a cosmological
+mechanism is suggested. This case raises the possibility of anthropic selection
+of other parameters in addition. Further requirements needed for a consistent
+cosmology are discussed.",0006088v2
+2000-07-07,Finite pion width effects on the rho--meson,"We study the influence of the finite damping width of pions on the in-medium
+properties of the rho-meson in an interacting meson gas model at finite
+temperature. Using vector dominance also implications on the resulting dilepton
+spectra from the decay of the rho-meson are presented. A set of coupled Dyson
+equations with self energies up to the sunset diagram level is solved self
+consistently. Following a Phi-derivable scheme the self energies are
+dynamically determined by the self consistent propagators. Some problems
+concerning the self consistent treatment of vector or gauge bosons on the
+propagator level, in particular, if coupled to currents arising from particles
+with a sizable damping width, are discussed.",0007070v3
+2000-08-31,New Regime for Dense String Networks,"We uncover a new transient regime that reconciles the apparent inconsistency
+of the Martins Shellard one scale damped string evolution model with the
+initial conditions predicted by the Kibble mechanism for string formation in a
+second order phase transition. This regime carries (in a short cosmic time
+$\sim .1 t_c$) the dense string network created by the Kibble {\it{mechanism}}
+to the (dilute) Kibble {\it{regime}} in which friction dominated strings remain
+till times $t_* \sim (M_P/T_c)^2 t_c$. This is possible beacause the cosmic
+time at the phase transition ($t_c$) is much larger than the damping time scale
+$l_f\sim T_c^2/T^3$. Our result has drastic implications for various non-GUT
+scale string mediated mechanisms.}",0008330v1
+2001-01-25,The Fermion Boson Interaction Within the Linear Sigma Model at Finite Temperature,"We reinvestigate the interaction of massless fermions with massless bosons at
+finite temperature. Specifically, we calculate the self-energy of massless
+fermions due the interaction with massless bosons at high temperature, which is
+the region where thermal effects are maximal. The calculations are concentrated
+in the limit of vanishing fermion three momentum and after considering the
+effective fermion and boson dressed masses, we obtain the damping rate of the
+fermion up to order $g^3$. It is shown that in the limit $k_0 \ll T$ the
+fermion acquire a thermal mass of order $gT$ and the leading term of the
+fermion damping rate is of order $g^2T+g^3T$.",0101283v3
+2001-11-02,Quark Number Susceptibility in Hard Thermal Loop Approximation,"We calculate the quark number susceptibility in the deconfined phase of QCD
+using the hard thermal loop (HTL) approximation for the quark propagator. This
+improved perturbation theory takes into account important medium effects such
+as thermal quark masses and Landau damping in the quark-gluon plasma. We
+explicitly show that the Landau damping part in the quark propagator for
+spacelike quark momenta does not contribute to the quark number susceptibility
+due to the quark number conservation. We find that the quark number
+susceptibility only due to the collective quark modes deviates from that of
+free one around the critical temperature but approaches free results at
+infinite temperature limit. The results are in conformity with recent lattice
+calculations.",0111022v4
+2001-12-29,Damped $\sin(β-α)$ of Higgs couplings and the lightest Higgs production at $γγ$ colliders in MSSM,"In the decoupling limit, $M^2_{A^0} \gg M^2_Z$, the heavy CP-even, CP-odd and
+charged Higgs boson masses are nearly degenerate, $\sin(\beta-\alpha)$
+approaches 1, and the lightest CP-even Higgs boson almost displays the same
+properties as the Standard Model Higgs boson. But the stop and sbottom sector
+can change this pattern through radiative corrections. We find that there are
+parameter regions at small, moderate and large $\tan\beta$ in MSSM under
+experimental constraints of $(g-2)_{\mu}$ and $b\to s\gamma$, where
+$\sin^2(\beta-\alpha)$ is damped (say below 0.8), which has a significant
+effect on Higgs couplings $g_{h^0VV} (V=W^\pm,Z^0)$ and $g_{h^0\gamma\gamma}$.
+We discuss its impact on the lightest CP-even Higgs production at
+$\gamma\gamma$ colliders.",0112356v1
+2004-05-31,Gauge dependence of the fermion quasiparticle poles in hot gauge theories,"The gauge dependence of the complex fermion quasiparticle poles corresponding
+to soft collective excitations is studied in hot gauge theories at one-loop
+order and next-to-leading order in the high-temperature expansion, with a view
+towards going beyond the leading order hard thermal loops and resummations
+thereof. We find that for collective excitations of momenta k ~ eT the
+dispersion relations are gauge independent, but the corresponding damping rates
+are gauge dependent. For k<<eT and in k \to 0 limit, both the dispersion
+relations and the damping rates are found to be gauge dependent. The gauge
+dependence of the position of the complex quasiparticle poles signals the need
+for resummation. Possible cancellation of the leading gauge dependence at
+two-loop order in the case of QED is briefly discussed.",0406002v2
+2004-11-09,Numerical investigation of friction in inflaton equations of motion,"The equation of motion for the expectation value of a scalar quantum field
+does not have the local form that is commonly assumed in studies of
+inflationary cosmology. We have recently argued that the true, temporally
+non-local equation of motion does not possess a time-derivative expansion and
+that the conversion of inflaton energy into particles is not, in principle,
+described by the friction term estimated from linear response theory. Here, we
+use numerical methods to investigate whether this obstacle to deriving a local
+equation of motion is purely formal, or of some quantitative importance. Using
+a simple scalar-field model, we find that, although the non-equilibrium
+evolution can exhibit significant damping, this damping is not well described
+by the local equation of motion obtained from linear response theory. It is
+possible that linear response theory does not apply to the situation we study
+only because thermalization turns out to be slow, but we argue that that the
+large discrepancies we observe indicate a failure of the local approximation at
+a more fundamental level.",0411130v1
+2006-03-03,Damping of supernova neutrino transitions in stochastic shock-wave density profiles,"Supernova neutrino flavor transitions during the shock wave propagation are
+known to encode relevant information not only about the matter density profile
+but also about unknown neutrino properties, such as the mass hierarchy (normal
+or inverted) and the mixing angle theta_13. While previous studies have
+focussed on ""deterministic"" density profiles, we investigate the effect of
+possible stochastic matter density fluctuations in the wake of supernova shock
+waves. In particular, we study the impact of small-scale fluctuations on the
+electron (anti)neutrino survival probability, and on the observable spectra of
+inverse-beta-decay events in future water-Cherenkov detectors. We find that
+such fluctuations, even with relatively small amplitudes, can have significant
+damping effects on the flavor transition pattern, and can partly erase the
+shock-wave imprint on the observable time spectra, especially for
+sin^2(theta_13) > O(10^-3).",0603033v2
+2006-08-11,Constraining SuperWIMPy and Warm Subhalos with Future Submillilensing,"We propose to observe QSO-galaxy strong lens systems to give a new constraint
+on the damping scale of the initial fluctuations. We find that the future
+observation of submilliarc scale astrometric shifts of the multiple lensed
+images of QSOs would find \sim 10^{(3-9)} M_{\odot} subhalos inside the
+macrolens halo. The superweakly interacting massive particles (superWIMPs)
+produced from a WIMP decay and the warm dark matter (WDM) particles that
+predict a comoving damping scale larger than \sim 2 kpc can be constrained if
+\sim 10^3 M_{\odot} subhalos are detected.",0608126v2
+2006-11-15,Time-to-Space Conversion in Neutrino Oscillations,"We study the neutrino oscillation problem in the framework of the wave packet
+formalism. The neutrino state is described by a packet located initially in a
+region S (source) and detected in another region D at a distance R from S. We
+examine how the oscillation probability as a function of variable R can be
+derived from he oscillation probability as a function of time t, the latter
+being found by using the Schrodinger equation. We justify the known
+prescription ""t --> R/c"" without referring to a specific form of the neutrino
+wave packet and only assuming the finiteness of its support. The effect of the
+oscillation damping at large R is revealed. For an illustration, an explicit
+expression for the damping factor is obtained using Gaussian packet.",0611202v1
+1998-09-11,Damping and reaction rates and wave function renormalization of fermions in hot gauge theories,"We examine the relation between the damping rate of a chiral fermion mode
+propagating in a hot plasma and the rate at which the mode approaches
+equilibrium. We show how these two quantities, obtained from the imaginary part
+of the fermion self-energy, are equal when the reaction rate is defined using
+the appropriate wave function of the mode in the medium. As an application, we
+compute the production rate of hard axions by Compton-like scattering processes
+in a hot QED plasma starting from both, the axion self-energy and the electron
+self-energy. We show that the latter rate coincides with the former only when
+this is computed using the corresponding medium spinor modes.",9809083v2
+2003-12-28,A mechanism of the large-scale damping in the CMB anisotropy,"We present a mechanism through which a certain class of short-distance cutoff
+affects the CMB anisotropies at large angular scales. Our analysis is performed
+in two steps. The first is given in an intuitive way, using the property of the
+inflationary universe that quantum fluctuations of an inflaton field become
+classical after crossing the Hubble horizon. We give a condition for a cutoff
+to yield a damping on large scales, and show that the holographic cutoff
+introduced in the preceding paper (hep-th/0307029) does satisfy the condition.
+The second analysis is carried out by setting an initial condition such that
+each mode of inflaton starts as the vacuum fluctuation of the Hamiltonian when
+being released from the constraint of cutoff. The first intuitive discussion is
+then shown to be correct qualitatively.",0312298v7
+2005-03-03,Scalar field perturbations of the Schwarzschild black hole in the Gödel Universe,"We investigate the scalar field perturbations of the 4+1-dimensional
+Schwarzschild black hole immersed in a G\""{o}del Universe, described by the
+Gimon-Hashimoto solution.This may model the influence of the possible rotation
+of the Universe upon the radiative processes near a black hole. In the regime
+when the scale parameter $j$ of the G\""{o}del background is small, the
+oscillation frequency is linearly decreasing with $j$, while the damping time
+is increasing. The quasinormal modes are damping, implying stability of the
+Schwarzschild-G\""{o}del space-time against scalar field perturbations. The
+approximate analytical formula for large multipole numbers is found.",0503029v2
+2005-06-28,Liouville Decoherence in a Model of Flavour Oscillations in the presence of Dark Energy,"We study in some detail the master equation, and its solution in a simplified
+case modelling flavour oscillations of a two-level system, stemming from the
+Liouville-string approach to quantum space time foam. In this framework we
+discuss the appearance of diffusion terms and decoherence due to the
+interaction of low-energy string matter with space-time defects, such as
+D-particles in the specific model of ``D-particle foam'', as well as dark
+energy contributions. We pay particular attention to contrasting the decoherent
+role of a cosmological constant in inducing exponential quantum damping in the
+evolution of low-energy observables, such as the probability of flavour
+oscillations, with the situation where the dark energy relaxes to zero for
+asymptotically large times, in which case such a damping is absent. Our
+findings may be of interest to (astrophysical) tests of quantum space-time foam
+models in the not-so-distant future.",0506242v1
+2005-08-25,The Dynamics of Small Instanton Phase Transitions,"The small instanton transition of a five-brane colliding with one end of the
+S1/Z2 interval in heterotic M-theory is discussed, with emphasis on the
+transition moduli, their potential function and the associated non-perturbative
+superpotential. Using numerical methods, the equations of motion of these
+moduli coupled to an expanding Friedmann-Robertson-Walker spacetime are solved
+including non-perturbative interactions. It is shown that the five-brane
+collides with the end of the interval at a small instanton. However, the moduli
+then continue to evolve to an isolated minimum of the potential, where they are
+trapped by gravitational damping. The torsion free sheaf at the small instanton
+is ``smoothed out'' into a vector bundle at the isolated minimum, thus
+dynamically completing the small instanton phase transition. Radiative damping
+at the origin of moduli space is discussed and shown to be insufficient to trap
+the moduli at the small instanton point.",0508190v2
+2006-02-16,Exit from a basin of attraction for stochastic weakly damped nonlinear Schrödinger equations,"We consider weakly damped nonlinear Schr\""odinger equations perturbed by a
+noise of small amplitude. The small noise is either complex and of additive
+type or real and of multiplicative type. It is white in time and colored in
+space. Zero is an asymptotically stable equilibrium point of the deterministic
+equations. We study the exit from a neighborhood of zero, invariant by the flow
+of the deterministic equation, in $\xLtwo$ or in $\xHone$. Due to noise, large
+fluctuations off zero occur. Thus, on a sufficiently large time scale, exit
+from these domains of attraction occur. A formal characterization of the small
+noise asymptotic of both the first exit times and the exit points is given.",0602350v1
+2006-04-07,"Quasi-periodic attractors, Borel summability and the Bryuno condition for strongly dissipative systems","We consider a class of ordinary differential equations describing
+one-dimensional analytic systems with a quasi-periodic forcing term and in the
+presence of damping. In the limit of large damping, under some generic
+non-degeneracy condition on the force, there are quasi-periodic solutions which
+have the same frequency vector as the forcing term. We prove that such
+solutions are Borel summable at the origin when the frequency vector is either
+any one-dimensional number or a two-dimensional vector such that the ratio of
+its components is an irrational number of constant type. In the first case the
+proof given simplifies that provided in a previous work of ours. We also show
+that in any dimension $d$, for the existence of a quasi-periodic solution with
+the same frequency vector as the forcing term, the standard Diophantine
+condition can be weakened into the Bryuno condition. In all cases, under a
+suitable positivity condition, the quasi-periodic solution is proved to
+describe a local attractor.",0604162v1
+2006-06-30,Uniform attractors for non-autonomous wave equations with nonlinear damping,"We consider dynamical behavior of non-autonomous wave-type evolutionary
+equations with nonlinear damping, critical nonlinearity, and time-dependent
+external forcing which is translation bounded but not translation compact
+(i.e., external forcing is not necessarily time-periodic, quasi-periodic or
+almost periodic). A sufficient and necessary condition for the existence of
+uniform attractors is established using the concept of uniform asymptotic
+compactness. The required compactness for the existence of uniform attractors
+is then fulfilled by some new a priori estimates for concrete wave type
+equations arising from applications. The structure of uniform attractors is
+obtained by constructing a skew product flow on the extended phase space for
+the norm-to-weak continuous process.",0606776v1
+2001-04-17,Scattering and radiation damping in gyroscopic Lorentz electrodynamic,"Relativistic massive Lorentz electrodynamics (LED) is studied in a
+``gyroscopic setup'' where the electromagnetic fields and the particle spin are
+the only dynamical degrees of freedom.
+  A rigorous proof of the global existence and uniqueness of the dynamics is
+given for essentially the whole range of field strengths reasonable for a
+classical theory.
+  For a class of rotation-reflection symmetric field data it is shown that the
+dynamics also satisfies the world-line equations for a non-moving Lorentz
+electron, thus furnishing rigorous solutions of the full system of nonlinear
+equations of LED.
+  The previously proven soliton dynamics of the Lorentz electron is further
+illucidated by showing that rotation-reflection symmetric deviations from the
+soliton state of the renormalized particle die out exponentially fast through
+radiation damping if the electrostatic mass is smaller than the bare rest mass.",0104023v2
+2002-06-18,Hamiltonian and Linear-Space Structure for Damped Oscillators: I. General Theory,"The phase space of $N$ damped linear oscillators is endowed with a bilinear
+map under which the evolution operator is symmetric. This analog of
+self-adjointness allows properties familiar from conservative systems to be
+recovered, e.g., eigenvectors are ""orthogonal"" under the bilinear map and obey
+sum rules, initial-value problems are readily solved and perturbation theory
+applies to the_complex_ eigenvalues. These concepts are conveniently
+represented in a biorthogonal basis.",0206026v2
+2002-06-17,Hamiltonian and Linear-Space Structure for Damped Oscillators: II. Critical Points,"The eigenvector expansion developed in the preceding paper for a system of
+damped linear oscillators is extended to critical points, where eigenvectors
+merge and the time-evolution operator $H$ assumes a Jordan-block structure. The
+representation of the bilinear map is obtained in this basis. Perturbations
+$\epsilon\Delta H$ around an $M$-th order critical point generically lead to
+eigenvalue shifts $\sim\epsilon^{1/M}$ dependent on only_one_ matrix element,
+with the $M$ eigenvalues splitting in equiangular directions in the complex
+plane. Small denominators near criticality are shown to cancel.",0206027v2
+2002-06-22,Yank and Hooke's constant group theoretically,"We study the second central extension of the (1+1) Aristotle Lie.We find that
+the first central extension admit four orbits on the dual of second central
+extension of the (1+1) Aristotle Lie group.The generic orbit is characterised
+by a Hooke's constant k and a yank y.If the physics of the orbit is studied
+with respect the evolution in time,it represents an elementary system with
+internal energy U in a posotion-momentum under the conjugation of a Hooke's
+force and a damping one proportional to the velocity as in particle
+mechanics.If the physics of the orbit is studied with respect the evolution in
+space, it represents an elementary system with an internal momentum P under the
+conjugation of a kind of Hooke's force and a damping one proportional to a
+slowness, slowness usually used in time travel waves.",0206038v1
+2004-02-24,Classical harmonic oscillator with Dirac-like parameters and possible applications,"We obtain a class of parametric oscillation modes that we call K-modes with
+damping and absorption that are connected to the classical harmonic oscillator
+modes through the ""supersymmetric"" one-dimensional matrix procedure similar to
+relationships of the same type between Dirac and Schroedinger equations in
+particle physics. When a single coupling parameter, denoted by K, is used, it
+characterizes both the damping and the dissipative features of these modes.
+Generalizations to several K parameters are also possible and lead to
+analytical results. If the problem is passed to the physical optics (and/or
+acoustics) context by switching from the oscillator equation to the
+corresponding Helmholtz equation, one may hope to detect the K-modes as
+waveguide modes of specially designed waveguides and/or cavities",0402065v2
+2000-02-22,Front motion for phase transitions in systems with memory,"We consider the Allen-Cahn equations with memory (a partial
+integro-differential convolution equation). The prototype kernels are
+exponentially decreasing functions of time and they reduce the
+integrodifferential equation to a hyperbolic one, the damped Klein-Gordon
+equation. By means of a formal asymptotic analysis we show that to the leading
+order and under suitable assumptions on the kernels, the integro-differential
+equation behave like a hyperbolic partial differential equation obtained by
+considering prototype kernels: the evolution of fronts is governed by the
+extended, damped Born-Infeld equation. We also apply our method to a system of
+partial integro-differential equations which generalize the classical phase
+field equations with a non-conserved order parameter and describe the process
+of phase transitions where memory effects are present.",0002039v1
+2002-03-01,Excitation of travelling multibreathers in anharmonic chains,"We study the dynamics of the ""externally"" forced and damped Fermi-Pasta-Ulam
+(FPU) 1D lattice. The forcing has the spatial symmetry of the Fourier mode with
+wavenumber p and oscillates sinusoidally in time with the frequency omega. When
+omega is in the phonon band, the p-mode becomes modulationally unstable above a
+critical forcing, which we determine analytically in terms of the parameters of
+the system. For omega above the phonon band, the instability of the p-mode
+leads to the formation of a travelling multibreather, that, in the
+low-amplitude limit could be described in terms of soliton solutions of a
+suitable driven-damped nonlinear Schroedinger (NLS) equation. Similar
+mechanisms of instability could show up in easy-axis magnetic structures, that
+are governed by such NLS equations.",0203002v1
+2003-03-21,Global well-posedness and multi-tone solutions of a class of nonlinear nonlocal cochlear models in hearing,"We study a class of nonlinear nonlocal cochlear models of the transmission
+line type, describing the motion of basilar membrane (BM) in the cochlea. They
+are damped dispersive partial differential equations (PDEs) driven by time
+dependent boundary forcing due to the input sounds. The global well-posedness
+in time follows from energy estimates. Uniform bounds of solutions hold in case
+of bounded nonlinear damping. When the input sounds are multi-frequency tones,
+and the nonlinearity in the PDEs is cubic, we construct smooth quasi-periodic
+solutions (multi-tone solutions) in the weakly nonlinear regime, where new
+frequencies are generated due to nonlinear interaction. When the input is two
+tones at frequencies $f_1$, $f_2$ ($f_1 < f_2$), and high enough intensities,
+numerical results illustrate the formation of combination tones at $2 f_1 -f_2$
+and $2f_2 -f_1$, in agreement with hearing experiments. We visualize the
+frequency content of solutions through the FFT power spectral density of
+displacement at selected spatial locations on BM.",0303048v1
+2004-05-11,Analytical approach to soliton ratchets in asymmetric potentials,"We use soliton perturbation theory and collective coordinate ansatz to
+investigate the mechanism of soliton ratchets in a driven and damped asymmetric
+double sine-Gordon equation. We show that, at the second order of the
+perturbation scheme, the soliton internal vibrations can couple {\it
+effectively}, in presence of damping, to the motion of the center of mass,
+giving rise to transport. An analytical expression for the mean velocity of the
+soliton is derived. The results of our analysis confirm the internal mode
+mechanism of soliton ratchets proposed in [Phys. Rev. E {\bf 65} 025602(R)
+(2002)].",0405023v1
+2005-02-16,Controlling soliton explosions,"We investigate the dynamics of solitons in generalized Klein-Gordon equations
+in the presence of nonlinear damping and spatiotemporal perturbations. We will
+present different mechanisms for soliton explosions. We show (both analytically
+and numerically) that some space-dependent perturbations or nonlinear damping
+can make the soliton internal mode unstable leading to soliton explosion. We
+will show that, in some cases, while some conditions are satisfied, the soliton
+explodes becoming a permanent, extremely complex, spatiotemporal dynamics. We
+believe these mechanisms can explain some of the phenomena that recently have
+been reported to occur in excitable media. We present a method for controlling
+soliton explosions.",0502033v1
+2005-07-22,Global existence in infinite lattices of nonlinear oscillators: The Discrete Klein-Gordon equation,"Pointing out the difference between the Discrete Nonlinear Schr\""odinger
+equation with the classical power law nonlinearity-for which solutions exist
+globally, independently of the sign and the degree of the nonlinearity, the
+size of the initial data and the dimension of the lattice-we prove either
+global existence or nonexistence in time, for the Discrete Klein-Gordon
+equation with the same type of nonlinearity (but of ``blow-up'' sign), under
+suitable conditions on the initial data, and some times on the dimension of the
+lattice. The results, consider both the conservative and the linearly damped
+lattice. Similarities and differences with the continuous counterparts, are
+remarked. We also make a short comment, on the existence of excitation
+thresholds, for forced solutions of damped and parametrically driven,
+Klein-Gordon lattices.",0507044v5
+1992-12-14,Poisson and Porter-Thomas Fluctuations in off-Yrast Rotational Transitions,"Fluctuations associated with stretched E2 transitions from high spin levels
+in nuclei around $^{168}$Yb are investigated by a cranked shell model extended
+to include residual two-body interactions. It is found that the gamma-ray
+energies behave like random variables and the energy spectra show the Poisson
+fluctuation, in the cranked mean field model without the residual interaction.
+With two-body residual interaction included, discrete transition pattern with
+unmixed rotational bands is still valid up to around 600 keV above yrast, in
+good agreement with experiments. At higher excitation energy, a gradual onset
+of rotational damping emerges. At 1.8 MeV above yrast, complete damping is
+observed with GOE type fluctuations for both energy levels and transition
+strengths(Porter-Thomas fluctuations).",9212006v1
+1993-11-25,Microscopic analysis of two-body correlations in light nuclei,"Within a nonperturbative dynamical two-body approach - based on coupled
+equations of motion for the one-body density matrix and the two-body
+correlation function - we study the distribution of occupation numbers in a
+correlated system close to the groundstate, the relaxation of single-particle
+excitations and the damping of collective modes. For this purpose the nonlinear
+equations of motion are solved numerically within a finite oscillator basis for
+the first time adopting short-range repulsive and long-range attractive
+two-body forces. We find in all cases that the formation of long- and
+short-range correlations and their mixing is related to the long- and
+short-range part of the nucleon-nucleon interaction which dominate the
+resummation of loop or ladder diagrams, respectively. However, the proper
+description of relaxation or damping phenomena is found to require both types
+of diagrams as well as the mixed terms simultaneously.",9311031v1
+1997-04-24,A Simple Mode on a Highly Excited Background: Collective Strength and Damping in the Continuum,"Simple states, such as isobaric analog states or giant resonances, embedded
+into continuum are typical for mesoscopic many-body quantum systems. Due to the
+coupling to compound states in the same energy range, a simple mode acquires a
+damping width (""internal"" dynamics). When studied experimentally with the aid
+of various reactions, such states reveal enhanced cross sections in specific
+channels at corresponding resonance energies (""external"" dynamics which include
+direct decay of a simple mode and decays of intrinsic compound states through
+their own channels). We consider the interplay between internal and external
+dynamics using a general formalism of the effective nonhermitian hamiltonian
+and looking at the situation both from ""inside"" (strength functions and
+spreading widths) and from ""outside"" (S-matrix, cross sections and delay
+times). The restoration of isospin purity and disappearance of the collective
+strength of giant resonances at high excitation energy are discussed as
+important particular manifestations of this complex interplay.",9704055v1
+1998-02-27,New collective mode due to collisional coupling,"Starting from a nonmarkovian conserving relaxation time approximation for
+collisions we derive coupled dispersion relations for asymmetric nuclear
+matter. The isovector and isoscalar modes are coupled due to asymmetric nuclear
+meanfield acting on neutrons and protons differently. A further coupling is
+observed by collisional correlations. The latter one leads to the appearance of
+a new soft mode besides isoscalar and isovector modes in the system. We suggest
+that this mode might be observable in asymmetric systems. This soft mode
+approaches the isovector mode for high temperatures. At the same time the
+isovector mode remains finite and approaches a constant value at higher
+temperatures showing a transition from zero sound like damping to first sound.
+The damping of the new soft mode is first sound like at all temperatures.",9802083v1
+1998-10-12,Response function beyond mean field of neutron-rich nuclei,"The damping of single-particle and collective motion in exotic isotopes is a
+new topic and its study may shed light on basic problems of nuclear dynamics.
+For instance, it is known that nuclear structure calculations are not able, as
+a rule, to account completely for the empirical single-particle damping. In
+this contribution, we present calculations of the single-particle self-energy
+in the case of the neutron-rich light nucleus $^{28}$O, by taking proper care
+of the continuum, and we show that there are important differences with the
+case of nuclei along the valley of stability.",9810033v1
+1999-04-14,Scaling Analysis of Fluctuating Strength Function,"We propose a new method to analyze fluctuations in the strength function
+phenomena in highly excited nuclei. Extending the method of multifractal
+analysis to the cases where the strength fluctuations do not obey power scaling
+laws, we introduce a new measure of fluctuation, called the local scaling
+dimension, which characterizes scaling behavior of the strength fluctuation as
+a function of energy bin width subdividing the strength function. We discuss
+properties of the new measure by applying it to a model system which simulates
+the doorway damping mechanism of giant resonances. It is found that the local
+scaling dimension characterizes well fluctuations and their energy scales of
+fine structures in the strength function associated with the damped collective
+motions.",9904037v1
+1999-07-07,Pair creation: back-reactions and damping,"We solve the quantum Vlasov equation for fermions and bosons, incorporating
+spontaneous pair creation in the presence of back-reactions and collisions.
+Pair creation is initiated by an external impulse field and the source term is
+non-Markovian. A simultaneous solution of Maxwell's equation in the presence of
+feedback yields an internal current and electric field that exhibit plasma
+oscillations with a period tau_pl. Allowing for collisions, these oscillations
+are damped on a time-scale, tau_r, determined by the collision frequency.
+Plasma oscillations cannot affect the early stages of the formation of a
+quark-gluon plasma unless tau_r >> tau_pl and tau_pl approx. 1/Lambda_QCD
+approx 1 fm/c.",9907027v1
+2000-10-23,Barrier penetration and rotational damping of thermally excited superdeformed nuclei,"We construct a microscopic model of thermally excited superdeformed states
+that describes both the barrier penetration mechanism, leading to the decay-out
+transitions to normal deformed states, and the rotational damping causing
+fragmentation of rotational E2 transitions. We describe the barrier penetration
+by means of a tunneling path in the two-dimensional deformation energy surface,
+which is calculated with the cranked Nilsson-Strutinsky model. The individual
+excited superdeformed states and associated E2 transition strengths are
+calculated by the shell model diagonalization of the many-particle many-hole
+excitations interacting with the delta-type residual two-body force. The effect
+of the decay-out on the excited superdeformed states are discussed in detail
+for $^{152}$Dy, $^{143}$Eu and $^{192}$Hg.",0010074v1
+1996-02-22,Stability of Travelling Waves for a Damped Hyperbolic Equation,"We consider a nonlinear damped hyperbolic equation in $\real^n$, $1 \le n \le
+4$, depending on a positive parameter $\epsilon$. If we set $\epsilon=0$, this
+equation reduces to the well-known Kolmogorov-Petrovski-Piskunov equation. We
+remark that, after a change of variables, this hyperbolic equation has the same
+family of one-dimensional travelling waves as the KPP equation. Using various
+energy functionals, we show that, if $\epsilon >0$, these fronts are locally
+stable under perturbations in appropriate weighted Sobolev spaces. Moreover,
+the decay rate in time of the perturbed solutions towards the front of minimal
+speed $c=2$ is shown to be polynomial. In the one-dimensional case, if
+$\epsilon < 1/4$, we can apply a Maximum Principle for hyperbolic equations and
+prove a global stability result. We also prove that the decay rate of the
+perturbated solutions towards the fronts is polynomial, for all $c > 2$.",9602004v1
+1998-09-18,Stability of Propagating Fronts in Damped Hyperbolic Equations,"We consider the damped hyperbolic equation in one space dimension $\epsilon
+u_{tt} + u_t = u_{xx} + F(u)$, where $\epsilon$ is a positive, not necessarily
+small parameter. We assume that $F(0)=F(1)=0$ and that $F$ is concave on the
+interval $[0,1]$. Under these assumptions, our equation has a continuous family
+of monotone propagating fronts (or travelling waves) indexed by the speed
+parameter $c \ge c_*$. Using energy estimates, we first show that the
+travelling waves are locally stable with respect to perturbations in a weighted
+Sobolev space. Then, under additional assumptions on the non-linearity, we
+obtain global stability results using a suitable version of the hyperbolic
+Maximum Principle. Finally, in the critical case $c = c_*$, we use self-similar
+variables to compute the exact asymptotic behavior of the perturbations as $t
+\to +\infty$. In particular, setting $\epsilon = 0$, we recover several
+stability results for the travelling waves of the corresponding parabolic
+equation.",9809007v1
+1999-01-09,Cluster ionization via two-plasmon excitation,"We calculate the two-photon ionization of clusters for photon energies near
+the surface plasmon resonance. The results are expressed in terms of the
+ionization rate of a double plasmon excitation, which is calculated
+perturbatively. For the conditions of the experiment by Schlipper et al., we
+find an ionization rate of the order of 0.05-0.10 fs^(-1). This rate is used to
+determine the ionization probability in an external field in terms of the
+number of photons absorbed and the duration of the field. The probability also
+depends on the damping rate of the surface plasmon. Agreement with experiment
+can only be achieved if the plasmon damping is considerably smaller than its
+observed width in the room-temperature single-photon absorption spectrum.",9901008v1
+2000-08-01,Rectangular Waveguide HOM Couplers for a TESLA Superstructure,"Some modifications of a Rectangular Waveguide HOM couplers for TESLA
+superstructure have been investigated. These RWG HOM couplers are to be
+installed between the cavities of the superstructure and also at the both ends
+of it. We investigated a RWG HOM coupler attached to the beam pipe through the
+slots orientated along beam pipe axis (longitudinal slots), perpendicular to it
+(azimutal slots) and at some angle to this axis. For dipole modes of both
+polarizations damping two RWG in every design were used. This paper presents
+the results obtained for scaled-up setup at 3 GHz at room temperature. The
+advantages of HOM coupler with longitudinal slots for damping dipole modes and
+compact HOM coupler with slots at some angle to the axis are shown. Arrangement
+of HOM coupler in cryostat and heating due to HOM and FM losses are presented.
+Calculations and design of the feeding RWG coupler for superstructure are also
+presented.",0008001v1
+2000-08-14,Design of a 3 GHz Accelerator Structure for the CLIC Test Facility (CTF 3) Drive Beam,"For the CLIC two-beam scheme, a high-current, long-pulse drive beam is
+required for RF power generation. Taking advantage of the 3 GHz klystrons
+available at the LEP injector once LEP stops, a 180 MeV electron accelerator is
+being constructed for a nominal beam current of 3.5 A and 1.5 microsecond pulse
+length. The high current requires highly effective suppression of dipolar
+wakes. Two concepts are investigated for the accelerating structure design: the
+""Tapered Damped Structure"" developed for the CLIC main beam, and the ""Slotted
+Iris - Constant Aperture"" structure. Both use 4 SiC loads per cell for
+effective higher-order mode damping. A full-size prototype of the TDS structure
+has been built and tested successfully at full power. A first prototype of the
+SICA structure is being built.",0008052v1
+2000-08-17,Superconducting Superstructure for the TESLA Collider: New Results,"A new cavity-chain layout has been proposed for the main linac of the TESLA
+linear collider. This superstructure-layout is based upon four 7-cell
+superconducting standing-wave cavities, coupled by short beam pipes. The main
+advantages of the superstructure are an increase in the active accelerating
+length in TESLA and a saving in rf components, especially power couplers, as
+compared to the present 9-cell cavities. The proposed scheme allows to handle
+the field-flatness tuning and the HOM damping at sub-unit level, in contrast to
+standard multi-cell cavities. The superstructure-layout is extensively studied
+at DESY since 1999. Computations have been performed for the rf properties of
+the cavity-chain, the bunch-to-bunch energy spread and multibunch dynamics. A
+copper model of the superstructure has been built in order to compare with the
+simulations and for testing the field-profile tuning and the HOM damping
+scheme. A ""proof of principle"" niobium prototype of the superstructure is now
+under construction and will be tested with beam at the TESLA Test Facility in
+2001. In this paper we present latest results of these investigations.",0008104v1
+2000-08-20,An Investigation of Optimised Frequency Distributions for Damping Wakefields in X-Band Linacs for the NLC,"In the NLC (Next Linear Collider) small misalignments in each of the
+individual accelerator structures (or the accelerator cells) will give rise to
+wakefields which kick the beam from its electrical axis. This wakefield can
+cause BBU (Beam Break Up) or at the very least it will dilute the emittance of
+the beam. Several Gaussian detuned structures have been designed and tested [1]
+at SLAC and in this paper we explore new distributions with possibly better
+damping properties. The progress of the beam through approximately 5,000
+structures is monitored in phase space and results on this are presented.
+  [1] J.W. Wang et al, TUA03, LINAC2000",0008202v2
+2001-04-14,Parameters for a 30 GeV Undulator Test Facility in the FFTB/LCLS,"The parameters for a 30 GeV test beam are outlined for use with an undulator
+in the FFTB tunnel where the LCLS will eventually be housed. It is proposed to
+use the SLAC linac and damping rings in their present mode of operation for PEP
+II injection, where 30 GeV beams are also delivered at 10 Hz to the FFTB. High
+peak currents are obtained with the addition of a second bunch compressor in
+the linac. In order to minimize the synchrotron radiation induced emittance
+growth in the bunch compressor it is necessary to locate the new bunch
+compressor at the low-energy end of the linac, just after the damping rings.
+The bunch compressor is a duplicate of the LCLS chicane-style bunch compressor.
+This test beam would provide an exciting possibility to test LCLS undulator
+sections and provide a unique high-brightness source of incoherent X-rays and
+begin developing the LCLS experimental station. The facility will also act as a
+much needed accelerator test bed for the production, diagnostics and tuning of
+very short bunches in preparation for the LCLS after the photo injector is
+commissioned.",0104045v1
+2001-10-05,Characterization of a Low Frequency Power Spectral Density f^(-gamma) in a Threshold Model,"his study investigates the modifications of the thermal spectrum, at low
+frequency, induced by an external damping on a system in heat contact with
+internal fluctuating impurities. Those impurities can move among locations and
+their oscillations are associated with a loss function depending on the model.
+The fluctuation properties of the system are provided by a potential function
+shaped by wells, in such a way that jumps between the stationary positions are
+allowed. The power spectral density associated with this dissipation mechanism
+shows a f^(-gamma)tail. The interest of this problem is that many systems are
+characterized by a typical f^(-\gamma) spectral tail at low frequency. The
+model presented in this article is based on a threshold type behaviour and its
+generality allows applications in several fields. The effects of an external
+force, introduced to produce damping, are studied by using both analytical
+techniques and numerical simulations. The results obtained with the present
+model show that no reduction of the power spectral density is appreciable below
+the main peak of the spectral density.",0110019v1
+2002-05-13,Damping of electromagnetic waves in low-collision electron-ion plasmas,"Using previously developed method of two-dimensional Laplace transform we
+obtain the characteristic equations k(\omega) for electromagnetic waves in
+low-collision fully ionized plasma of a plane geometry. We apply here a new,
+different from the one used in our previous paper, iteration procedure of
+taking into account the Coulomb collisions. The waves are collisionally damping
+in the same extent as electromagnetic waves. Despite the different from
+previous paper form of the dispersion (poles) equation, the obtained decrements
+for fast and slow wave modes coincide with results obtained in our earlier
+paper, if one neglects the terms of higher orders in v^2/c^2, (v and c are
+electron and light velocities). We point out how one can determine mutually
+dependent boundary conditions allowing to eliminate simultaneously both the
+backward and kinematical waves for transversal as well as for longitudinal
+oscillations.",0205035v2
+2002-06-01,Intrabeam scattering analysis of measurements at KEK's ATF damping ring,"We derive a simple relation for estimating the relative emittance growth in x
+and y due to intrabeam scattering (IBS) in electron storage rings. We show that
+IBS calculations for the ATF damping ring, when using the formalism of
+Bjorken-Mtingwa, a modified formalism of Piwinski (where eta squared divided by
+beta has been replaced by the dispersion invariant), or a simple high-energy
+approximate formula all give results that agree well. Comparing theory,
+including the effect of potential well bunch lengthening, with a complete set
+of ATF steady-state beam size vs. current measurements we find reasonably good
+agreement for energy spread and horizontal emittance. The measured vertical
+emittance, however, is larger than theory in both offset (zero current
+emittance) and slope (emittance change with current). The slope error indicates
+measurement error and/or additional current-dependent physics at the ATF; the
+offset error, that the assumed Coulomb log is correct to within a factor of
+1.75.",0206003v1
+2002-08-24,Wakefield Band Partitioning In Linac Structures,"In the NLC project multiple bunches of electrons and positrons will be
+accelerated initially to a centre of mass of 500 GeV and later to 1 TeV or
+more. In the process of accelerating 192 bunches within a pulse train,
+wakefields are excited which kick the trailing bunches off axis and can cause
+luminosity dilution and BBU (Beam Break Up). Several structures to damp the
+wakefield have been designed and tested at SLAC and KEK and these have been
+found to successfully damp the wakefield [1]. However, these 2pi/3 structures
+suffered from electrical breakdown and this has prompted us to explore lower
+group velocity structures operating at higher fundamental mode phase advances.
+The wakefield partitioning amongst the bands has been found to change markedly
+with increased phase advance. Here we report on general trends in the kick
+factor and associated wakefield band partitioning in dipole bands as a function
+of phase advance of the synchronous mode in linacs. These results are
+applicable to both TW (travelling wave) and SW (standing wave) structures [1]
+R.M. Jones et al, PAC99, also SLAC-PUB-8103",0208086v1
+2003-01-30,Calculation of the Coherent Synchrotron Radiation Impedance from a Wiggler,"Most studies of Coherent Synchrotron Radiation (CSR) have only considered the
+radiation from independent dipole magnets. However, in the damping rings of
+future linear colliders, a large fraction of the radiation power will be
+emitted in damping wigglers. In this paper, the longitudinal wakefield and
+impedance due to CSR in a wiggler are derived in the limit of a large wiggler
+parameter $K$. After an appropriate scaling, the results can be expressed in
+terms of universal functions, which are independent of $K$. Analytical
+asymptotic results are obtained for the wakefield in the limit of large and
+small distances, and for the impedance in the limit of small and high
+frequencies.",0301073v1
+2003-10-02,Damping factors for the gap-tooth scheme,"An important class of problems exhibits macroscopically smooth behaviour in
+space and time, while only a microscopic evolution law is known. For such
+time-dependent multi-scale problems, the gap-tooth scheme has recently been
+proposed. The scheme approximates the evolution of an unavailable (in closed
+form) macroscopic equation in a macroscopic domain; it only uses appropriately
+initialized simulations of the available microscopic model in a number of small
+boxes. For some model problems, including numerical homogenization, the scheme
+is essentially equivalent to a finite difference scheme, provided we repeatedly
+impose appropriate algebraic constraints on the solution for each box. Here, we
+demonstrate that it is possible to obtain a convergent scheme without
+constraining the microscopic code, by introducing buffers that ""shield"" over
+relatively short times the dynamics inside each box from boundary effects. We
+explore and quantify the behavior of these schemes systematically through the
+numerical computation of damping factors of the corresponding coarse
+time-stepper, for which no closed formula is available.",0310014v1
+2004-07-31,Propagation of optical excitations by dipolar interactions in metal nanoparticle chains,"Dispersion relations for dipolar modes propagating along a chain of metal
+nanoparticles are calculated by solving the full Maxwell equations, including
+radiation damping. The nanoparticles are treated as point dipoles, which means
+the results are valid only for a/d <= 1/3, where a is the particle radius and d
+the spacing. The discrete modes for a finite chain are first calculated, then
+these are mapped onto the dispersion relations appropriate for the infinite
+chain. Computed results are given for a chain of 50-nm diameter Ag spheres
+spaced by 75 nm. We find large deviations from previous quasistatic results:
+Transverse modes interact strongly with the light line. Longitudinal modes
+develop a bandwidth more than twice as large, resulting in a group velocity
+that is more than doubled. All modes for which k_mode <= w/c show strongly
+enhanced decay due to radiation damping.",0408003v2
+2004-08-22,Tacoma Bridge Failure-- a Physical Model,"The cause of the collapse of the Tacoma Narrows Bridge has been a topic of
+much debate and confusion since the day it fell. Many mischaracterizations of
+the observed phenomena have limited the widespread understanding of the
+problem. Nevertheless, there has always been an abundance of evidence in favour
+of a negative damping model. Negative damping, or positive feedback, is
+responsible for many large amplitude oscillations observed in many
+applications. In this paper, we will explain some well-known examples of
+positive feedback. We will then present a feedback model, derived from
+fundamental physics, capable of explaining a number of features observed in the
+instabilities of many bridge decks. This model is supported by computational,
+experimental and historical data.",0408101v1
+2004-08-30,Short waves and cyclotron losses in the relativistic gyrokinetic theory,"Radiation damping of the motion of charged particles in relativistic,
+optically thin plasmas is described within the framework of the covariant
+gyrokinetic theory. It involves description of the collisionless
+single-particle dynamics as well as the Vlasov and Maxwell equations both
+written in the covariant formulation. The damping causes corrections to the
+phase-space trajectory of the particle, as well as to the form of the kinetic
+equation itself, due to the failure of conditions of the Liouville theorem.
+Both effects result independent of the gyrophase, which is retained as an
+ignorable variable. In addition, the applicability range of the covariant
+gyrokinetic theory is extended to describe short-wavelength perturbations with
+the background of zero parallel electric field. The presented theory is
+suitable for description of magnetized, relativistic, collisionless plasmas in
+the context of astrophysical or laboratory problems. Non-uniquenes of the
+gyrokinetic representation and consequences thereof are discussed.",0408128v1
+2004-11-02,Supersymmetric free-damped oscillators: Adaptive observer estimation of the Riccati parameter,"A supersymmetric class of free damped oscillators with three parameters has
+been obtained in 1998 by Rosu and Reyes through the factorization of the Newton
+equation. The supplementary parameter is the integration constant of the
+general Riccati solution. The estimation of the latter parameter is performed
+here by employing the recent adaptive observer scheme of Besancon et al., but
+applied in a nonstandard form in which a time-varying quantity containing the
+unknown Riccati parameter is estimated first. Results of computer simulations
+are presented to illustrate the good feasibility of this approach for a case in
+which the estimation is not easily accomplished by other means",0411019v2
+2004-11-05,Wave-kinetic description of nonlinear photons,"The nonlinear interaction, due to quantum electrodynamical (QED) effects,
+between photons is investigated using a wave-kinetic description. Starting from
+a coherent wave description, we use the Wigner transform technique to obtain a
+set of wave-kinetic equations, the so called Wigner-Moyal equations. These
+equations are coupled to a background radiation fluid, whose dynamics is
+determined by an acoustic wave equation. In the slowly varying acoustic limit,
+we analyse the resulting system of kinetic equations, and show that they
+describe instabilities, as well as Landau-like damping. The instabilities may
+lead to break-up and focusing of ultra-high intensity multi-beam systems, which
+in conjunction with the damping may result in stationary strong field
+structures. The results could be of relevance for the next generation of
+laser-plasma systems.",0411058v1
+2004-12-17,Optimal Determination of the Equilibrium Displacement of a Damped Harmonic Oscillator in the Presence of Thermal Noise,"Using a matched filter technique, we derive the minimum variance, unbiased
+estimator for the equilibrium displacement of a damped harmonic oscillator in
+thermal equilibrium when interactions with the thermal bath are the leading
+source of noise. We compare the variance in this optimal estimator with the
+variance in other, commonly used estimators in the presence of pure thermal
+noise and pure white noise. We also compare the variance in these estimators
+for a mixture of white and thermal noise. This result has implications for
+experimental design and the collection and analysis of data.",0412102v1
+2006-01-13,Atomic collider into dual-isotope magneto-optical trap,"When two of three pairs of the Gaussian laser beams of a traditional MOT are
+misaligned in the racetrack configuration the effective coordinate-dependent
+vortex force do arise. Then an atom is accelerated by this vortex force until
+its velocity not balanced by the damping force. This situation may produce a
+stable ring of revolving atoms of a certain radius. Due to the different
+frequency and laser beams intensity dependences of the vortex, damping and
+trapping forces it is possible to equalize the radii of two orbiting groups of
+atoms in two-species or dual-isotope magneto-optical trap and so to arrange a
+continuing collider of cooled atoms with the prescribed relative velocity. A
+collider setup for atoms of two different types rotating with different angular
+velocities along the same ring-like trajectory into MOT of the conventional
+six-beam geometry is proposed and designed on example of two rubidium isotopes
+Rb85 and Rb87.",0601097v1
+2006-12-07,On some peculiarities of electric field pulse propagation in electron Maxwellian plasma and its back response,"In the spirit of continued study of general plasma wave properties we
+investigated the boundary problem with the simplest form of electric field
+pulse at the edge x=0 of half-infinite uniform plasma slab with Maxwellian
+electron distribution function. In the case of longitudinal electric field
+pulse its traveling velocity is essentially other than in the case of harmonic
+waves; there is also no back response. In the case of transverse field pulse
+there takes place the bimodal propagation rate of the non-damping fast pulse
+signal and non-damping weak slow sign reversed pulse signals; some very weak
+response (echo) arises with a time delay in the near coordinate zone of
+formation of the asymptotical regime.",0612064v4
+1996-10-29,Bosonic Quantum Codes for Amplitude Damping,"Traditional quantum error correction involves the redundant encoding of k
+quantum bits using n quantum bits to allow the detection and correction of any
+t bit error. The smallest general t=1 code requires n=5 for k=1. However, the
+dominant error process in a physical system is often well known, thus inviting
+the question: given a specific error model, can more efficient codes be
+devised? We demonstrate new codes which correct just amplitude damping errors
+which allow, for example, a t=1, k=1 code using effectively n=4.6. Our scheme
+is based on using bosonic states of photons in a finite number of optical
+modes. We present necessary and sufficient conditions for the codes, and
+describe construction algorithms, physical implementation, and performance
+bounds.",9610043v1
+1997-01-16,Cooperative loss and decoherence in quantum computation and commuication,"Cooperative effects in the loss (the amplitude damping) and decoherence (the
+phase damping) of the qubits (two-state quantum systems) due to the inevitable
+coupling to the same environment are investigated. It is found that the qubits
+undergo the dissipation coherently in this case. In particular, for a special
+kind of input states (called the coherence-preserving states), whose form
+depends on the type of the coupling, loss and decoherence in quantum memory are
+much reduced. Based on this phenomenon, a scheme by encoding the general input
+states of the qubits into the corresponding coherence-preserving states is
+proposed for reducing the cooperative loss and decoherence in quantum
+computation or communication.",9701020v1
+1997-03-22,Preserving coherence in quantum computation by pairing quantum bits,"A scheme is proposed for protecting quantum states from both independent
+decoherence and cooperative decoherence. The scheme operates by pairing each
+qubit (two-state quantum system) with an ancilla qubit and by encoding the
+states of the qubits into the corresponding coherence-preserving states of the
+qubit-pairs. In this scheme, the amplitude damping (loss of energy) is
+prevented as well as the phase damping (dephasing) by a strategy called the
+free-Hamiltonian-elimination We further extend the scheme to include quantum
+gate operations and show that loss and decoherence during the gate operations
+can also be prevented.",9703040v2
+1997-06-10,Perturbative expansions for the fidelities and spatially correlated dissipation of quantum bits,"We construct generally applicable short-time perturbative expansions for some
+fidelities, such as the input-output fidelity, the entanglement fidelity, and
+the average fidelity. Successive terms of these expansions yield characteristic
+times for the damping of the fidelities involving successive powers of the
+Hamiltonian. The second-order results, which represent the damping rates of the
+fidelities, are extensively discussed. As an interesting application of these
+expansions, we use them to study the spatially-correlated dissipation of
+quantum bits. Spatial correlations in the dissipation are described by a
+correlation function. Explicit conditions are derived for independent
+decoherence and for collective decoherence.",9706020v2
+1998-05-27,Measurement Process In a Two-Barrier System,"The description of a measuring process, such as that which occurs when a
+quantum point contact (QPC) detector is influenced by a nearby external
+electron which can take up two possible positions, provides a interesting
+application of the method of quantum damping. We find a number of new effects,
+due to the complete treatment of phases afforded by the formalism, although our
+results are generally similiar to those of other treatments, particularly to
+those of Buks et al.
+  These are effects depending on the phase shift in the detector, effects which
+depend on the direction of the measuring current, and in addition to damping or
+dissipative effects, an energy shift of the measured system. In particular, the
+phase shift effect leads to the conclusion that there can be effects of
+""observation"" even when the two barriers in question pass the same current.
+  The nature of the current through the barriers and its statistics is
+discussed, giving a description of correlations in the current due to
+""measurement"" and of the origin of ""telegraphic"" signals.",9805081v2
+1998-10-06,Cumulant expansion for studying damped quantum solitons,"The quantum statistics of damped optical solitons is studied using
+cumulant-expansion techniques. The effect of absorption is described in terms
+of ordinary Markovian relaxation theory, by coupling the optical field to a
+continuum of reservoir modes. After introduction of local bosonic field
+operators and spatial discretization pseudo-Fokker-Planck equations for
+multidimensional s-parameterized phase-space functions are derived. These
+partial differential equations are equivalent to an infinite set of ordinary
+differential equations for the cumulants of the phase-space functions.
+Introducing an appropriate truncation condition, the resulting finite set of
+cumulant evolution equations can be solved numerically. Solutions are presented
+in Gaussian approximation and the quantum noise is calculated, with special
+emphasis on squeezing and the recently measured spectral photon-number
+correlations [Spaelter et al., Phys. Rev. Lett. 81, 786 (1998)].",9810018v3
+1999-02-10,Quantum noise in the position measurement of a cavity mirror undergoing Brownian motion,"We perform a quantum theoretical calculation of the noise power spectrum for
+a phase measurement of the light output from a coherently driven optical cavity
+with a freely moving rear mirror. We examine how the noise resulting from the
+quantum back action appears among the various contributions from other noise
+sources. We do not assume an ideal (homodyne) phase measurement, but rather
+consider phase modulation detection, which we show has a different shot noise
+level. We also take into account the effects of thermal damping of the mirror,
+losses within the cavity, and classical laser noise. We relate our theoretical
+results to experimental parameters, so as to make direct comparisons with
+current experiments simple. We also show that in this situation, the standard
+Brownian motion master equation is inadequate for describing the thermal
+damping of the mirror, as it produces a spurious term in the steady-state phase
+fluctuation spectrum. The corrected Brownian motion master equation [L. Diosi,
+Europhys. Lett. {\bf 22}, 1 (1993)] rectifies this inadequacy.",9902040v1
+2000-06-07,Phenomenological approach to introduce damping effects on radiation field states,"In this work we propose an approach to deal with radiation field states which
+incorporates damping effects at zero temperature. By using some well known
+results on dissipation of a cavity field state, obtained by standard ab-initio
+methods, it was possible to infer through a phenomenological way the explicit
+form for the evolution of the state vector for the whole system: the
+cavity-field plus reservoir. This proposal turns out to be of extreme
+convenience to account for the influence of the reservoir over the cavity
+field.
+  To illustrate the universal applicability of our approach we consider the
+attenuation effects on cavity-field states engineering. A proposal to maximize
+the fidelity of the process is presented.",0006035v2
+2001-09-28,Decoherence in trapped ions due to polarization of the residual background gas,"We investigate the mechanism of damping and heating of trapped ions
+associated with the polarization of the residual background gas induced by the
+oscillating ions themselves. Reasoning by analogy with the physics of surface
+electrons in liquid helium, we demonstrate that the decay of Rabi oscillations
+observed in experiments on 9Be+ can be attributed to the polarization phenomena
+investigated here. The measured sensitivity of the damping of Rabi oscillations
+with respect to the vibrational quantum number of a trapped ion is also
+predicted in our polarization model.",0109156v1
+2002-06-18,Five Lectures On Dissipative Master Equations,"1 First Lecture: Basics
+  1.1 Physical Derivation of the Master Equation
+  1.2 Some Simple Implications
+  1.3 Steady State
+  1.4 Action to the Left
+  2 Second Lecture: Eigenvalues and Eigenvectors of L
+  2.1 A Simple Case First
+  2.2 The General Case
+  3 Third Lecture: Completeness of the Damping Bases
+  3.1 Phase Space Functions
+  3.2 Completeness of the Eigenvectors of L
+  3.3 Positivity Conservation
+  3.4 Lindblad Form of Liouville Operators
+  4 Fourth Lecture: Quantum-Optical Applications
+  4.1 Periodically Driven Damped Oscillator
+  4.2 Conditional and Unconditional Evolution
+  4.3 Physical Signicance of Statistical Operators
+  5 Fifth Lecture: Statistics of Detected Atoms
+  5.1 Correlation Functions
+  5.2 Waiting Time Statistics
+  5.3 Counting Statistics",0206116v1
+2002-10-02,Radiation damping and decoherence in quantum electrodynamics,"The processes of radiation damping and decoherence in Quantum Electrodynamics
+are studied from an open system's point of view. Employing functional
+techniques of field theory, the degrees of freedom of the radiation field are
+eliminated to obtain the influence phase functional which describes the reduced
+dynamics of the matter variables. The general theory is applied to the dynamics
+of a single electron in the radiation field. From a study of the wave packet
+dynamics a quantitative measure for the degree of decoherence, the decoherence
+function, is deduced. The latter is shown to describe the emergence of
+decoherence through the emission of bremsstrahlung caused by the relative
+motion of interfering wave packets. It is argued that this mechanism is the
+most fundamental process in Quantum Electrodynamics leading to the destruction
+of coherence, since it dominates for short times and because it is at work even
+in the electromagnetic field vacuum at zero temperature. It turns out that
+decoherence trough bremsstrahlung is very small for single electrons but
+extremely large for superpositions of many-particle states.",0210013v1
+2003-01-08,"Dissipation, Emergent Quantization and Quantum Fluctuations","We review some aspects of the quantization of the damped harmonic oscillator.
+We derive the exact action for a damped mechanical system in the frame of the
+path integral formulation of the quantum Brownian motion problem developed by
+Schwinger and by Feynman and Vernon. The doubling of the phase-space degrees of
+freedom for dissipative systems and thermal field theories is discussed and the
+doubled variables are related to quantum noise effects. The 't Hooft proposal,
+according to which the loss of information due to dissipation in a classical
+deterministic system manifests itself in the quantum features of the system, is
+analyzed and the quantum spectrum of the harmonic oscillator is shown to be
+originated from the dissipative character of the original classical
+deterministic system.",0301031v1
+2004-01-28,Bloch Equations and Completely Positive Maps,"The phenomenological dissipation of the Bloch equations is reexamined in the
+context of completely positive maps. Such maps occur if the dissipation arises
+from a reduction of a unitary evolution of a system coupled to a reservoir. In
+such a case the reduced dynamics for the system alone will always yield
+completely positive maps of the density operator. We show that, for Markovian
+Bloch maps, the requirement of complete positivity imposes some Bloch
+inequalities on the phenomenological damping constants. For non-Markovian Bloch
+maps some kind of Bloch inequalities involving eigenvalues of the damping basis
+can be established as well. As an illustration of these general properties we
+use the depolarizing channel with white and colored stochastic noise.",0401177v1
+2004-02-12,Non-Markovian Quantum Trajectories Versus Master Equations: Finite Temperature Heat Bath,"The interrelationship between the non-Markovian stochastic Schr\""odinger
+equations and the corresponding non-Markovian master equations is investigated
+in the finite temperature regimes. We show that the general finite temperature
+non-Markovian trajectories can be used to derive the corresponding
+non-Markovian master equations. A simple, yet important solvable example is the
+well-known damped harmonic oscillator model in which a harmonic oscillator is
+coupled to a finite temperature reservoir in the rotating wave approximation.
+The exact convolutionless master equation for the damped harmonic oscillator is
+obtained by averaging the quantum trajectories relying upon no assumption of
+coupling strength or time scale. The master equation derived in this way
+automatically preserves the positivity, Hermiticity and unity.",0402086v2
+2005-04-27,Decoherence models and their effects on quantum maps and algorithms,"In this work we study several models of decoherence and how different quantum
+maps and algorithms react when perturbed by them. Following closely Ref. [1],
+generalizations of the three paradigmatic one single qubit quantum channels
+(these are the depolarizing channel, the phase damping channel and the
+amplitude damping channel) for the case of an arbitrarily-sized
+finite-dimensional Hilbert space are presented, as well as other types of noise
+in phase space. More specifically, Grover's search algorithm's response to
+decoherence is analyzed; together with those of a family of quantum versions of
+chaotic and regular classical maps (the baker's map and the cat maps). A
+relationship between how sensitive to decoherence a quantum map is and the
+degree of complexity in the dynamics of its associated classical counterpart is
+observed; resulting in a clear tendency to react the more decoherently the more
+complex the associated classical dynamics is.",0504211v1
+2005-09-22,Semiclassical quantization of non-Hamiltonian dynamical systems without memory,"We propose a new method of quantization of a wide class of dynamical systems
+that originates directly from the equations of motion. The method is based on
+the correspondence between the classical and the quantum Poisson brackets,
+postulated by Dirac. This correspondence applied to open (non-Hamiltonian)
+systems allows one to point out the way of transition from the quantum
+description based on the Lindblad equation to the dynamical description of
+their classical analogs by the equations of motion and vice versa. As the
+examples of using of the method we describe the procedure of the quantization
+of three widely considered dynamical systems: 1) the harmonic oscillator with
+friction, 2) the oscillator with a nonlinear damping that simulates the process
+of the emergence of the limit cycle, and 3) the system of two periodic rotators
+with a weak interaction that synchronizes their oscillations. We discuss a
+possible application of the method for a description of quantum fluctuations in
+Josephson junctions with a strong damping and for the quantization of open
+magnetic systems with a dissipation and a pumping.",0509159v1
+2005-11-15,Classical Phase Space Density for the Relativistic Hydrogen Atom,"Quantum mechanics is considered to arise from an underlying classical
+structure (``hidden variable theory'', ``sub-quantum mechanics''), where
+quantum fluctuations follow from a physical noise mechanism. The stability of
+the hydrogen ground state can then arise from a balance between Lorentz damping
+and energy absorption from the noise. Since the damping is weak, the ground
+state phase space density should predominantly be a function of the conserved
+quantities, energy and angular momentum.
+  A candidate for this phase space density is constructed for ground state of
+the relativistic hydrogen problem of a spinless particle. The first excited
+states and their spherical harmonics are also considered in this framework. The
+analytic expression of the ground state energy can be reproduced, provided
+averages of certain products are replaced by products of averages. This
+analysis puts forward that quantum mechanics may arise from an underlying
+classical level as a slow variable theory, where each new quantum operator
+relates to a new, well separated time interval.",0511144v1
+2006-01-10,Quantum Brownian motion and the Third Law of thermodynamics,"The quantum thermodynamic behavior of small systems is investigated in
+presence of finite quantum dissipation. We consider the archetype cases of a
+damped harmonic oscillator and a free quantum Brownian particle. A main finding
+is that quantum dissipation helps to ensure the validity of the Third Law. For
+the quantum oscillator, finite damping replaces the zero-coupling result of an
+exponential suppression of the specific heat at low temperatures by a power-law
+behavior. Rather intriguing is the behavior of the free quantum Brownian
+particle. In this case, quantum dissipation is able to restore the Third Law:
+Instead of being constant down to zero temperature, the specific heat now
+vanishes proportional to temperature with an amplitude that is inversely
+proportional to the ohmic dissipation strength. A distinct subtlety of finite
+quantum dissipation is the result that the various thermodynamic functions of
+the sub-system do not only depend on the dissipation strength but depend as
+well on the prescription employed in their definition.",0601056v1
+2006-03-13,Decoherence induced by a phase-damping reservoir,"A phase damping reservoir composed by $N$-bosons coupled to a system of
+interest through a cross-Kerr interaction is proposed and its effects on
+quantum superpo sitions are investigated. By means of analytical calculations
+we show that: i-) the reservoir induces a Gaussian decay of quantum coherences,
+and ii-) the inher ent incommensurate character of the spectral distribution
+yields irreversibility . A state-independent decoherence time and a master
+equation are both derived an alytically. These results, which have been
+extended for the thermodynamic limit, show that nondissipative decoherence can
+be suitably contemplated within the EI D approach. Finally, it is shown that
+the same mechanism yielding decoherence ar e also responsible for inducing
+dynamical disentanglement.",0603109v2
+2007-01-21,Casimir-Polder forces on excited atoms in the strong atom-field coupling regime,"Based on macroscopic quantum electrodynamics in linear media, we develop a
+general theory of the resonant Casimir-Polder force on an excited two-level
+atom in the presence of arbitrary linear bodies, with special emphasis on the
+strong-coupling regime where reabsorption of an emitted photon can give rise to
+(vacuum) Rabi oscillations. We first derive a simple time-independent
+expression for the force by using a dressed-state approximation. For initially
+single-quantum excited atom-field systems we then study the dynamics of the
+force by starting from the Lorentz force and evaluating its average as a
+function of time. For strong atom-field coupling, we find that the force may
+undergo damped Rabi oscillations. The damping is due to the decay of both the
+atomic excitation and the field excitation, and both amplitude and mean value
+of the oscillations depend on the chosen initial state.",0701151v2
+2007-02-07,Protecting an optical qubit against photon loss,"We consider quantum error-correction codes for multimode bosonic systems,
+such as optical fields, that are affected by amplitude damping. Such a process
+is a generalization of an erasure channel. We demonstrate that the most
+accessible method of transforming optical systems with the help of passive
+linear networks has limited usefulness in preparing and manipulating such
+codes. These limitations stem directly from the recoverability condition for
+one-photon loss. We introduce a three-photon code protecting against the first
+order of amplitude damping, i.e. a single photon loss, and discuss its
+preparation using linear optics with single-photon sources and conditional
+detection. Quantum state and process tomography in the code subspace can be
+implemented using passive linear optics and photon counting. An experimental
+proof-of-principle demonstration of elements of the proposed quantum error
+correction scheme for a one-photon erasure lies well within present
+technological capabilites.",0702075v1
+1995-02-03,Shock waves in the dissipative Toda lattice,"We consider the propagation of a shock wave (SW) in the damped Toda lattice.
+The SW is a moving boundary between two semi-infinite lattice domains with
+different densities. A steadily moving SW may exist if the damping in the
+lattice is represented by an ``inner'' friction, which is a discrete analog of
+the second viscosity in hydrodynamics. The problem can be considered
+analytically in the continuum approximation, and the analysis produces an
+explicit relation between the SW's velocity and the densities of the two
+phases. Numerical simulations of the lattice equations of motion demonstrate
+that a stable SW establishes if the initial velocity is directed towards the
+less dense phase; in the opposite case, the wave gradually spreads out. The
+numerically found equilibrium velocity of the SW turns out to be in a very good
+agreement with the analytical formula even in a strongly discrete case. If the
+initial velocity is essentially different from the one determined by the
+densities (but has the correct sign), the velocity does not significantly
+alter, but instead the SW adjusts itself to the given velocity by sending
+another SW in the opposite direction.",9502001v1
+2007-04-04,An integral field spectroscopic survey for high redshift damped Lyman-alpha galaxies,"We search for galaxy counterparts to damped Lyman-alpha absorbers (DLAs) at
+z>2 towards nine quasars, which have 14 DLAs and 8 sub-DLAs in their spectra.
+We use integral field spectroscopy to search for Ly-alpha emission line objects
+at the redshifts of the absorption systems. Besides recovering two previously
+confirmed objects, we find six statistically significant candidate Ly-alpha
+emission line objects. The candidates are identified as having wavelengths
+close to the DLA line where the background quasar emission is absorbed. In
+comparison with the six currently known Ly-alpha emitting DLA galaxies the
+candidates have similar line fluxes and line widths, while velocity offsets
+between the emission lines and systemic DLA redshifts are larger. The impact
+parameters are larger than 10 kpc, and lower column density systems are found
+at larger impact parameters. Assuming that a single gas cloud extends from the
+QSO line of sight to the location of the candidate emission line, we find that
+the average candidate DLA galaxy is surrounded by neutral gas with an
+exponential scale length of ~5 kpc.",0704.0654v1
+2007-04-06,9.7 micrometer Silicate Absorption in a Damped Lyman-alpha Absorber at z=0.52,"We report a detection of the 9.7 micrometer silicate absorption feature in a
+damped Lyman-alpha (DLA) system at z_{abs} = 0.524 toward AO0235+164, using the
+Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope. The feature
+shows a broad shallow profile over about 8-12 micrometers in the absorber rest
+frame and appears to be > 15 sigma significant in equivalent width. The feature
+is fit reasonably well by the silicate absorption profiles for laboratory
+amorphous olivine or diffuse Galactic interstellar clouds. To our knowledge,
+this is the first indication of 9.7 micrometer silicate absorption in a DLA. We
+discuss potential implications of this finding for the nature of the dust in
+quasar absorbers. Although the feature is relatively shallow (tau_{9.7} =
+0.08-0.09), it is about 2 times deeper than expected from extrapolation of the
+tau_{9.7} vs. E(B-V) relation known for diffuse Galactic interstellar clouds.
+Further studies of the 9.7 micrometer silicate feature in quasar absorbers will
+open a new window on the dust in distant galaxies.",0704.0826v2
+2007-04-17,Boolean network model predicts cell cycle sequence of fission yeast,"A Boolean network model of the cell-cycle regulatory network of fission yeast
+(Schizosaccharomyces Pombe) is constructed solely on the basis of the known
+biochemical interaction topology. Simulating the model in the computer,
+faithfully reproduces the known sequence of regulatory activity patterns along
+the cell cycle of the living cell. Contrary to existing differential equation
+models, no parameters enter the model except the structure of the regulatory
+circuitry. The dynamical properties of the model indicate that the biological
+dynamical sequence is robustly implemented in the regulatory network, with the
+biological stationary state G1 corresponding to the dominant attractor in state
+space, and with the biological regulatory sequence being a strongly attractive
+trajectory. Comparing the fission yeast cell-cycle model to a similar model of
+the corresponding network in S. cerevisiae, a remarkable difference in
+circuitry, as well as dynamics is observed. While the latter operates in a
+strongly damped mode, driven by external excitation, the S. pombe network
+represents an auto-excited system with external damping.",0704.2200v1
+2007-05-08,Optical dilution and feedback cooling of a gram-scale oscillator to 6.9 mK,"We report on use of a radiation pressure induced restoring force, the optical
+spring effect, to optically dilute the mechanical damping of a 1 gram suspended
+mirror, which is then cooled by active feedback (cold damping). Optical
+dilution relaxes the limit on cooling imposed by mechanical losses, allowing
+the oscillator mode to reach a minimum temperature of 6.9 mK, a factor of
+~40000 below the environmental temperature. A further advantage of the optical
+spring effect is that it can increase the number of oscillations before
+decoherence by several orders of magnitude. In the present experiment we infer
+an increase in the dynamical lifetime of the state by a factor of ~200.",0705.1018v2
+2007-05-14,Electron-muon heat conduction in neutron star cores via the exchange of transverse plasmons,"We calculate the thermal conductivity of electrons and muons kappa_{e-mu}
+produced owing to electromagnetic interactions of charged particles in neutron
+star cores and show that these interactions are dominated by the exchange of
+transverse plasmons (via the Landau damping of these plasmons in
+nonsuperconducting matter and via a specific plasma screening in the presence
+of proton superconductivity). For normal protons, the Landau damping strongly
+reduces kappa_{e-mu} and makes it temperature independent. Proton
+superconductivity suppresses the reduction and restores the Fermi-liquid
+behavior kappa_{e-mu} ~ 1/T. Comparing with the thermal conductivity of
+neutrons kappa_n, we obtain kappa_{e-mu}> kappa_n for T>2 GK in normal matter
+and for any T in superconducting matter with proton critical temperatures
+T_c>3e9 K. The results are described by simple analytic formulae.",0705.1963v1
+2007-05-24,Measurement of Newtonian fluid slip using a torsional ultrasonic oscillator,"The composite torsional ultrasonic oscillator, a versatile experimental
+system, can be used to investigate slip of Newtonian fluid at a smooth surface.
+A rigorous analysis of slip-dependent damping for the oscillator is presented.
+Initially, the phenomenon of finite surface slip and the slip length are
+considered for a half-space of Newtonian fluid in contact with a smooth,
+oscillating solid surface. Definitions are revisited and clarified in light of
+inconsistencies in the literature. We point out that, in general oscillating
+flows, Navier's slip length b is a complex number. An intuitive velocity
+discontinuity parameter of unrestricted phase is used to describe the effect of
+slip on measurement of viscous shear damping. The analysis is applied to the
+composite oscillator and preliminary experimental work for a 40 kHz oscillator
+is presented. The Non-Slip Boundary Condition (NSBC) has been verified for a
+hydrophobic surface in water to within ~60 nm of |b|=0 nm. Experiments were
+carried out at shear rate amplitudes between 230 and 6800 /s, corresponding to
+linear displacement amplitudes between 3.2 and 96 nm.",0705.3498v3
+2007-06-05,Waves and instabilities in dissipative rotating superfluid neutron stars,"We discuss wave propagation in rotating superfluid neutron star cores, taking
+into account the vortex mediated mutual friction force. For models where the
+two fluids co-rotate in the unperturbed state, our analysis clarifies the role
+of chemical coupling and entrainment for sound and inertial waves. We also
+investigate the mutual friction damping, providing results that demonstrate the
+well-known fact that sound waves propagating along a vortex array are undamped.
+We show that the same is not true for inertial waves, which are damped by the
+mutual friction regardless of the propagation direction. We then include the
+vortex tension, which arises due to local vortex curvature. Focussing on purely
+transverse inertial waves, we derive the small correction that the tension
+induces in the wave frequency. Finally, we allow for a relative linear flow in
+the background (along the rotation axis). In this case we show how the mutual
+friction coupling may induce a dynamical instability in the inertial waves. We
+discuss the critical flow required for the instability to be present, its
+physical interpretation and the possible relevance it may have for neutron star
+physics.",0706.0672v1
+2007-07-20,Dissipation-Scale Turbulence in the Solar Wind,"We present a cascade model for turbulence in weakly collisional plasmas that
+follows the nonlinear cascade of energy from the large scales of driving in the
+MHD regime to the small scales of the kinetic Alfven wave regime where the
+turbulence is dissipated by kinetic processes. Steady-state solutions of the
+model for the slow solar wind yield three conclusions: (1) beyond the observed
+break in the magnetic energy spectrum, one expects an exponential cut-off; (2)
+the widely held interpretation that this dissipation range obeys power-law
+behavior is an artifact of instrumental sensitivity limitations; and, (3) over
+the range of parameters relevant to the solar wind, the observed variation of
+dissipation range spectral indices from -2 to -4 is naturally explained by the
+varying effectiveness of Landau damping, from an undamped prediction of -7/3 to
+a strongly damped index around -4.",0707.3149v1
+2007-08-09,An algorithm for detecting oscillatory behavior in discretized data: the damped-oscillator oscillator detector,"We present a simple algorithm for detecting oscillatory behavior in discrete
+data. The data is used as an input driving force acting on a set of simulated
+damped oscillators. By monitoring the energy of the simulated oscillators, we
+can detect oscillatory behavior in data. In application to in vivo deep brain
+basal ganglia recordings, we found sharp peaks in the spectrum at 20 and 70 Hz.
+The algorithm is also compared to the conventional fast Fourier transform and
+circular statistics techniques using computer generated model data, and is
+found to be comparable to or better than fast Fourier transform in test cases.
+Circular statistics performed poorly in our tests.",0708.1341v1
+2007-08-22,The dynamics of vortex generation in superfluid 3He-B,"A profound change occurs in the stability of quantized vortices in externally
+applied flow of superfluid 3He-B at temperatures ~ 0.6 Tc, owing to the rapidly
+decreasing damping in vortex motion with decreasing temperature. At low damping
+an evolving vortex may become unstable and generate a new independent vortex
+loop. This single-vortex instability is the generic precursor to turbulence. We
+investigate the instability with non-invasive NMR measurements on a rotating
+cylindrical sample in the intermediate temperature regime (0.3 - 0.6) Tc. From
+comparisons with numerical calculations we interpret that the instability
+occurs at the container wall, when the vortex end moves along the wall in
+applied flow.",0708.3003v2
+2007-08-26,Geodesic plasma flows instabilities of Riemann twisted solar loops,"Riemann and sectional curvatures of magnetic twisted flux tubes in Riemannian
+manifold are computed to investigate the stability of the plasma astrophysical
+tubes. The geodesic equations are used to show that in the case of thick
+magnetic tubes, the curvature of planar (Frenet torsion-free) tubes have the
+effect ct of damping the flow speed along the tube. Stability of geodesic flows
+in the Riemannian twisted thin tubes (almost filaments), against constant
+radial perturbations is investigated by using the method of negative sectional
+curvature for unstable flows. No special form of the flow like Beltrami flows
+is admitted, and the proof is general for the case of thin magnetic flux tubes.
+In the magnetic equilibrium state, the twist of the tube is shown to display
+also a damping effect on the toroidal velocity of the plasma flow. It is found
+that for positive perturbations and angular speed of the flow, instability is
+achieved, since the sectional Ricci curvature of the magnetic twisted tube
+metric is negative. Solar flare production may appear from these geometrical
+instabilities of the twisted solar loops.",0708.3473v1
+2007-09-05,Phonon bottleneck in the low-excitation limit,"The phonon-bottleneck problem in the relaxation of two-level systems (spins)
+via direct phonon processes is considered numerically in the weak-excitation
+limit where the Schroedinger equation for the spin-phonon system simplifies.
+The solution for the relaxing spin excitation p(t), emitted phonons n_k(t),
+etc. is obtained in terms of the exact many-body eigenstates. In the absence of
+phonon damping Gamma_{ph} and inhomogeneous broadening, p(t) approaches the
+bottleneck plateau p_\infty > 0 with strongly damped oscillations, the
+frequency being related to the spin-phonon splitting Delta at the avoided
+crossing. For any Gamma_{ph} > 0 one has p(t) -> 0 but in the case of strong
+bottleneck the spin relaxation rate is much smaller than Gamma_{ph} and p(t) is
+nonexponential. Inhomogeneous broadening exceeding Delta partially alleviates
+the bottleneck and removes oscillations of p(t). The line width of emitted
+phonons, as well as Delta, increase with the strength of the bottleneck, i.e.,
+with the concentration of spins.",0709.0556v1
+2007-09-13,Distribution of PageRank Mass Among Principle Components of the Web,"We study the PageRank mass of principal components in a bow-tie Web Graph, as
+a function of the damping factor c. Using a singular perturbation approach, we
+show that the PageRank share of IN and SCC components remains high even for
+very large values of the damping factor, in spite of the fact that it drops to
+zero when c goes to one. However, a detailed study of the OUT component reveals
+the presence ``dead-ends'' (small groups of pages linking only to each other)
+that receive an unfairly high ranking when c is close to one. We argue that
+this problem can be mitigated by choosing c as small as 1/2.",0709.2016v1
+2007-10-02,Oscillating Starless Cores: The Nonlinear Regime,"In a previous paper, we modeled the oscillations of a thermally-supported
+(Bonnor-Ebert) sphere as non-radial, linear perturbations following a standard
+analysis developed for stellar pulsations. The predicted column density
+variations and molecular spectral line profiles are similar to those observed
+in the Bok globule B68 suggesting that the motions in some starless cores may
+be oscillating perturbations on a thermally supported equilibrium structure.
+However, the linear analysis is unable to address several questions, among them
+the stability, and lifetime of the perturbations. In this paper we simulate the
+oscillations using a three-dimensional numerical hydrodynamic code. We find
+that the oscillations are damped predominantly by non-linear mode-coupling, and
+the damping time scale is typically many oscillation periods, corresponding to
+a few million years, and persisting over the inferred lifetime of gobules.",0710.0625v1
+2007-10-08,Jet quenching parameter \hat q in the stochastic QCD vacuum with Landau damping,"We argue that the radiative energy loss of a parton traversing the
+quark-gluon plasma is determined by Landau damping of soft modes in the plasma.
+Using this idea, we calculate the jet quenching parameter of a gluon. The
+calculation is done in SU(3) quenched QCD within the stochastic vacuum model.
+At the LHC-relevant temperatures, the result depends on the gluon condensate,
+the vacuum correlation length, and the gluon Debye mass. Numerically, when the
+temperature varies from T=T_c to T=900 MeV, the jet quenching parameter rises
+from \hat q=0 to approximately 1.8 GeV^2/fm. We compare our results with the
+predictions of perturbative QCD and other calculations.",0710.1540v2
+2007-11-07,Tuning the effective coupling of an AFM lever to a thermal bath,"Fabrication of Nano-Electro-Mechanical-Systems (NEMS) of high quality is
+nowadays extremely efficient. These NEMS will be used as sensors and actuators
+in integrated systems. Their use however raises questions about their interface
+(actuation, detection, read out) with external detection and control systems.
+Their operation implies many fundamental questions related to single particle
+effects such as Coulomb blockade, light matter interactions such as radiation
+pressure, thermal effects, Casimir forces and the coupling of nanosystems to
+external world (thermal fluctuations, back action effect). Here we specifically
+present how the damping of an oscillating cantilever can be tuned in two
+radically different ways: i) through an electro-mechanical coupling in the
+presence of a strong Johnson noise, ii) through an external feedback control of
+thermal fluctuations which is the cold damping closely related to Maxwell's
+demon. This shows how the interplay between MEMS or NEMS external control and
+their coupling to a thermal bath can lead to a wealth of effects that are
+nowadays extensively studied in different areas.",0711.1024v1
+2008-01-21,Collective cyclotron motion of the relativistic plasma in graphene,"We present a theory of the finite temperature thermo-electric response
+functions of graphene, in the hydrodynamic regime induced by electron-electron
+collisions. In moderate magnetic fields, the Dirac particles undergo a
+collective cyclotron motion with a temperature-dependent relativistic cyclotron
+frequency proportional to the net charge density of the Dirac plasma. In
+contrast to the undamped cyclotron pole in Galilean-invariant systems (Kohn's
+theorem), here there is a finite damping induced by collisions between the
+counter-propagating particles and holes. This cyclotron motion shows up as a
+damped pole in the frequency dependent conductivities, and should be readily
+detectable in microwave measurements at room temperature. We also discuss the
+large Nernst effect to be expected in graphene.",0801.2970v3
+2008-01-25,Sound waves and solitons in hot and dense nuclear matter,"Assuming that nuclear matter can be treated as a perfect fluid, we study the
+propagation of perturbations in the baryon density. The equation of state is
+derived from a relativistic mean field model, which is a variant of the
+non-linear Walecka model. The expansion of the Euler and continuity equations
+of relativistic hydrodynamics around equilibrium configurations leads to
+differential equations for the density fluctuations. We solve them numerically
+for linear and spherical perturbations and follow the time evolution of the
+initial pulses. For linear perturbations we find single soliton solutions and
+solutions with one or more solitons followed by radiation. Depending on the
+equation of state a strong damping may occur. Spherical perturbations are
+strongly damped and almost do not propagate. We study these equations also for
+matter at finite temperature. Finally we consider the limiting case of shock
+wave formation.",0801.3938v1
+2008-01-28,Qualitative Analysis of Forced Response of Blisks With Friction Ring Dampers,"A damping strategy for blisks (integrally bladed disks) of turbomachinery
+involving a friction ring is investigated. These rings, located in grooves
+underside the wheel of the blisks, are held in contact by centrifugal loads and
+the energy is dissipated when relative motions between the ring and the disk
+occur. A representative lumped parameter model of the system is introduced and
+the steady-state nonlinear response is derived using a multi-harmonic balance
+method combined with an AFT procedure where the friction force is calculated in
+the time domain. Numerical simulations are presented for several damper
+characteristics and several excitation configurations. From these results, the
+performance of this damping strategy is discussed and some design guidelines
+are given.",0801.4350v1
+2008-01-29,Long Term Evolution of Magnetic Turbulence in Relativistic Collisionless Shocks,"We study the long term evolution of magnetic fields generated by an initially
+unmagnetized collisionless relativistic $e^+e^-$ shock. Our 2D particle-in-cell
+numerical simulations show that downstream of such a Weibel-mediated shock,
+particle distributions are approximately isotropic, relativistic Maxwellians,
+and the magnetic turbulence is highly intermittent spatially, nonpropagating,
+and decaying. Using linear kinetic theory, we find a simple analytic form for
+these damping rates. Our theory predicts that overall magnetic energy decays
+like $(\omega_p t)^{-q}$ with $q \sim 1$, which compares favorably with
+simulations, but predicts overly rapid damping of short wavelength modes.
+Magnetic trapping of particles within the magnetic structures may be the origin
+of this discrepancy. We conclude that initially unmagnetized relativistic
+shocks in electron-positron plasmas are unable to form persistent downstream
+magnetic fields. These results put interesting constraints on synchrotron
+models for the prompt and afterglow emission from GRBs.",0801.4583v1
+2008-02-20,Mechanical mode dependence of bolometric back-action in an AFM microlever,"Two back action (BA) processes generated by an optical cavity based detection
+device can deeply transform the dynamical behavior of an AFM microlever: the
+photothermal force or the radiation pressure. Whereas noise damping or
+amplifying depends on optical cavity response for radiation pressure BA, we
+present experimental results carried out under vacuum and at room temperature
+on the photothermal BA process which appears to be more complex. We show for
+the first time that it can simultaneously act on two vibration modes in
+opposite direction: noise on one mode is amplified whereas it is damped on
+another mode. Basic modeling of photothermal BA shows that dynamical effect on
+mechanical mode is laser spot position dependent with respect to mode shape.
+This analysis accounts for opposite behaviors of different modes as observed.",0802.2763v2
+2008-02-21,Propagation of cosmic rays in the foam-like Universe,"The model of a classical spacetime foam is considered, which consists of
+static wormholes embedded in Minkowski spacetime. We examine the propagation of
+particles in such a medium and demonstrate that a single thin ray undergoes a
+specific damping in the density of particles depending on the traversed path
+and the distribution of wormholes. The missing particles are scattered around
+the ray. Wormholes was shown to form DM halos around point-like sources.
+Therefore, the correlation predicted between the damping and the amount of DM
+can be used to verify the topological nature of Dark Matter.",0802.3109v2
+2008-02-21,Damping by slow relaxing rare earth impurities in Ni80Fe20,"Doping NiFe by heavy rare earth atoms alters the magnetic relaxation
+properties of this material drastically. We show that this effect can be well
+explained by the slow relaxing impurity mechanism. This process is a
+consequence of the anisotropy of the on site exchange interaction between the
+4f magnetic moments and the conduction band. As expected from this model the
+magnitude of the damping effect scales with the anisotropy of the exchange
+interaction and increases by an order of magnitude at low temperatures. In
+addition our measurements allow us to determine the relaxation time of the 4f
+electrons as a function of temperature.",0802.3206v3
+2008-03-11,Domain wall motion of magnetic nanowires under a static field,"The propagation of a head-to-head magnetic domain-wall (DW) or a tail-to-tail
+DW in a magnetic nanowire under a static field along the wire axis is studied.
+Relationship between the DW velocity and DW structure is obtained from the
+energy consideration. The role of the energy dissipation in the field-driven DW
+motion is clarified. Namely, a field can only drive a domain-wall propagating
+along the field direction through the mediation of a damping. Without the
+damping, DW cannot propagate along the wire. Contrary to the common wisdom, DW
+velocity is, in general, proportional to the energy dissipation rate, and one
+needs to find a way to enhance the energy dissipation in order to increase the
+propagation speed. The theory provides also a nature explanation of the
+wire-width dependence of the DW velocity and velocity oscillation beyond Walker
+breakdown field.",0803.1531v1
+2008-03-11,"Equation of state for strongly interacting matter: collective effects, Landau damping and predictions for LHC","The equation of state (EOS) is of utmost importance for the description of
+the hydrodynamic phase of strongly interacting matter in relativistic heavy-ion
+collisions. Lattice QCD can provide useful information on the EOS, mainly for
+small net baryon densities. The QCD quasiparticle model provides a means to map
+lattice QCD results into regions relevant for a variety of experiments. We
+report here on effects of collectives modes and damping on the EOS. Some
+predictions for forthcoming heavy-ion collisions at LHC/ALICE are presented and
+perspectives for deriving an EOS for FAIR/CBM are discussed.",0803.1571v1
+2008-04-04,"Spin-charge coupling in a band ferromagnet: magnon-energy reduction, anomalous softening, and damping","The effects of correlation-induced coupling between spin and charge
+fluctuations on spin-wave excitations in a band ferromagnet are investigated by
+including self-energy and vertex corrections within a systematic
+inverse-degeneracy expansion scheme which explicitly preserves the Goldstone
+mode. Arising from the scattering of a magnon into intermediate spin-excitation
+states (including both magnon and Stoner excitations) accompanied with charge
+fluctuations in the majority spin band, this spin-charge coupling results not
+only in a substantial reduction of magnon energies but also in anomalous
+softening and significant magnon damping for zone-boundary modes lying within
+the Stoner gap. Our results are in good qualitative agreement with recent
+spin-wave excitation measurements in colossal magneto-resistive manganites and
+ferromagnetic ultrathin films of transition metals.",0804.0680v1
+2008-05-07,Noise Analysis and Noise-based Optimization for Resonant MEMS Structures,"This paper presents a detailed noise analysis and a noise-based optimization
+procedure for resonant MEMS structures. A design for high sensitivity of MEMS
+structures needs to take into account the noise shaping induced by damping
+phenomena at micro scale. The existing literature presents detailed models for
+the damping at microscale, but usually neglects them in the noise analysis
+process, assuming instead a white spectrum approximation for the
+mechano-thermal noise. The present work extends the implications of the complex
+gas-solid interaction into the field of noise analysis for mechanical sensors,
+and provides a semi-automatic procedure for behavioral macromodel extraction
+and sensor optimization with respect to signal-to-noise ratio.",0805.0927v1
+2008-05-07,Scaling crossovers in activated escape of nonequilibrium systems: a resonantly driven oscillator,"The rate of metastable decay in nonequilibrium systems is expected to display
+scaling behavior: i.e., the logarithm of the decay rate should scale as a power
+of the distance to a bifurcation point where the metastable state disappears.
+Recently such behavior was observed and some of the earlier predicted exponents
+were found in experiments on several types of systems described by a model of a
+modulated oscillator. Here we establish the range where different scaling
+behavior is displayed and show how the crossover between different types of
+scaling occurs. The analysis is done for a nonlinear oscillator with two
+coexisting stable states of forced vibrations. Our numerical calculations,
+based on the the instanton method allow the mapping of the entire parameter
+range of bi-stability. We find the regions where the scaling exponents are 1 or
+3/2, depending on the damping. The exponent 3/2 is found to extend much further
+from the bifurcation then were it would be expected to hold as a result of an
+over-damped soft mode. We also uncover a new scaling behavior with exponent of
+$\approx$ 1.3 which extends, numerically, beyond the close vicinity of the
+bifurcation point.",0805.0972v2
+2008-05-07,"Quantum Noise, Effective Temperature, and Damping in a Superconducting Single-Electron Transistor","We have directly measured the quantum noise of a superconducting
+single-electron transistor (S-SET) embedded in a microwave resonator consisting
+of a superconducting LC tank circuit. Using an effective bath description, we
+find that the S-SET provides damping of the resonator modes proportional to its
+differential conductance and has an effective temperature that depends strongly
+on the S-SET bias conditions. In the vicinity of a double Cooper pair
+resonance, when both resonances are red detuned the S-SET effective temperature
+can be well below both the ambient temperature and the energy scale of the bias
+voltage. When blue detuned, the S-SET shows negative differential conductivity,",0805.1037v1
+2008-05-08,Adaptive Affinity Propagation Clustering,"Affinity propagation clustering (AP) has two limitations: it is hard to know
+what value of parameter 'preference' can yield an optimal clustering solution,
+and oscillations cannot be eliminated automatically if occur. The adaptive AP
+method is proposed to overcome these limitations, including adaptive scanning
+of preferences to search space of the number of clusters for finding the
+optimal clustering solution, adaptive adjustment of damping factors to
+eliminate oscillations, and adaptive escaping from oscillations when the
+damping adjustment technique fails. Experimental results on simulated and real
+data sets show that the adaptive AP is effective and can outperform AP in
+quality of clustering results.",0805.1096v1
+2008-06-17,Damping of Fast Magnetohydrodynamic Oscillations in Quiescent Filament Threads,"High-resolution observations provide evidence about the existence of
+small-amplitude transverse oscillations in solar filament fine structures.
+These oscillations are believed to represent fast magnetohydrodynamic (MHD)
+waves and the disturbances are seen to be damped in short timescales of the
+order of 1 to 4 periods. In this Letter we propose that, due to the highly
+inhomogeneous nature of the filament plasma at the fine structure spatial
+scale, the phenomenon of resonant absorption is likely to operate in the
+temporal attenuation of fast MHD oscillations. By considering transverse
+inhomogeneity in a straight flux tube model we find that, for density
+inhomogeneities typical of filament threads, the decay times are of a few
+oscillatory periods only.",0806.2728v1
+2008-06-27,Global attractor and asymptotic smoothing effects for the weakly damped cubic Schrödinger equation in $L^2(\T)$,"We prove that the weakly damped cubic Schr\""odinger flow in $L^2(\T)$
+provides a dynamical system that possesses a global attractor. The proof relies
+on a sharp study of the behavior of the associated flow-map with respect to the
+weak $ L^2(\T) $-convergence inspired by a previous work of the author.
+Combining the compactness in $ L^2(\T) $ of the attractor with the approach
+developed by Goubet, we show that the attractor is actually a compact set of $
+H^2(\T) $. This asymptotic smoothing effect is optimal in view of the
+regularity of the steady states.",0806.4578v3
+2008-06-30,Thermal depinning of fluxons in discrete Josephson rings,"We study the thermal depinning of single fluxons in rings made of Josephson
+junctions. Due to thermal fluctuations a fluxon can be excited from its energy
+minima and move through the array, causing a voltage across each junction. We
+find that for the initial depinning, the fluxon behaves as a single particle
+and follows a Kramers-type escape law. However, under some conditions this
+single particle description breaks down. At low values of the discreteness
+parameter and low values of the damping, the depinning rate is larger than the
+single particle result would suggest. In addition, for some values of the
+parameters the fluxon can undergo low-voltage diffusion before switching to the
+high-voltage whirling mode. This type of diffusion is similar to phase
+diffusion in a single junction, but occurs without frequency-dependent damping.
+We study the switching to the whirling state as well.",0806.4828v1
+2008-07-03,Dependence of the decoherence of polarization states in phase-damping channels on the frequency spectrum envelope of photons,"We consider the decoherence of photons suffering in phase-damping channels.
+By exploring the evolutions of single-photon polarization states and two-photon
+polarization-entangled states, we find that different frequency spectrum
+envelopes of photons induce different decoherence processes. A white frequency
+spectrum can lead the decoherence to an ideal Markovian process. Some color
+frequency spectrums can induce asymptotical decoherence, while, some other
+color frequency spectrums can make coherence vanish periodically with variable
+revival amplitudes. These behaviors result from the non-Markovian effects on
+the decoherence process, which may give rise to a revival of coherence after
+complete decoherence.",0807.0536v3
+2008-07-17,"Planetary Migration in Resonance, the question of the Eccentricities : Les Houches contribution","The formation of resonant planets pairs in exoplanetary systems involves
+planetary migration inside the protoplanetary disc : an inwards migrating outer
+planet captures in Mean Motion Resonance an inner planet. During the migration
+of the resonant pair of planets, the eccentricities are expected to rise
+excessively, if no damping mechanism is applied on the inner planet. We express
+the required damping action to match the observations, and we show that the
+inner disk can play this role. This result applies for instance to the system
+GJ 876 : we reproduce the observed orbital elements through a fully
+hydrodynamical simulation of the evolution of the resonant planets.",0807.2828v2
+2008-07-18,Heavily Damped Motion of One-Dimensional Bose Gases in an Optical Lattice,"We study the dynamics of strongly correlated one-dimensional Bose gases in a
+combined harmonic and optical lattice potential subjected to sudden
+displacement of the confining potential. Using the time-evolving block
+decimation method, we perform a first-principles quantum many-body simulation
+of the experiment of Fertig {\it et al.} [Phys. Rev. Lett. {\bf 94}, 120403
+(2005)] across different values of the lattice depth ranging from the
+superfluid to the Mott insulator regimes. We find good quantitative agreement
+with this experiment: the damping of the dipole oscillations is significant
+even for shallow lattices, and the motion becomes overdamped with increasing
+lattice depth as observed. We show that the transition to overdamping is
+attributed to the decay of superfluid flow accelerated by quantum fluctuations,
+which occurs well before the emergence of Mott insulator domains.",0807.2898v2
+2008-07-21,Mutual friction in a cold color flavor locked superfluid and r-mode instabilities in compact stars,"Dissipative processes acting in rotating neutron stars are essential in
+preventing the growth of the r-mode instability. We estimate the damping time
+of r-modes of an hypothetical compact quark star made up by color flavor locked
+quark matter at a temperature $T \lesssim 0.01$ MeV. The dissipation that we
+consider is due to the the mutual friction force between the normal and the
+superfluid component arising from the elastic scattering of phonons with
+quantized vortices. This process is the dominant one for temperatures $T
+\lesssim 0.01$ MeV where the mean free path of phonons due to their
+self-interactions is larger than the radius of the star and they can be
+described as an ideal bosonic gas. We find that r-modes oscillations are
+efficiently damped by this mechanism for pulsars rotating at frequencies of the
+order of 1 Hz at most. Our analysis rules out the possibility that cold pulsars
+rotating at higher frequencies are entirely made up by color flavor locked
+quark matter.",0807.3264v2
+2008-07-23,Dynamical Backaction of Microwave Fields on a Nanomechanical Oscillator,"We measure the response and thermal motion of a high-Q nanomechanical
+oscillator coupled to a superconducting microwave cavity in the
+resolved-sideband regime where the oscillator's resonance frequency exceeds the
+cavity's linewidth. The coupling between the microwave field and mechanical
+motion is strong enough for radiation pressure to overwhelm the intrinsic
+mechanical damping. This radiation-pressure damping cools the fundamental
+mechanical mode by a factor of 5 below the thermal equilibrium temperature in a
+dilution refrigerator to a phonon occupancy of 140 quanta.",0807.3585v3
+2008-07-28,Shear Viscosity of the outer crust of Neutron stars: Ion Contribution,"The shear viscosity of the crust might have a damping effect on the amplitude
+of r-modes of rotating neutron stars. This damping has implications for the
+emission of gravitational waves. We calculate the contribution to the shear
+viscosity coming from the ions using both semi-analytical methods, that
+consider binary collisions, and Molecular Dynamics simulations. We compare
+these results with the contribution coming from electrons. We study how the
+shear viscosity depends on density for conditions of interest in neutron star
+envelopes and outer crusts. In the low density limit, we find good agreement
+between results of our molecular dynamics simulations and classical
+semi-analytic calculations.",0807.4353v2
+2008-07-28,Unusual decoherence in qubit measurements with a Bose-Einstein condensate,"We consider an electrostatic qubit located near a Bose-Einstein condensate
+(BEC) of noninteracting bosons in a double-well potential, which is used for
+qubit measurements. Tracing out the BEC variables we obtain a simple analytical
+expression for the qubit's density-matrix. The qubit's evolution exhibits a
+slow ($\propto1/\sqrt{t}$) damping of the qubit's coherence term, which however
+turns to be a Gaussian one in the case of static qubit. This stays in contrast
+to the exponential damping produced by most classical detectors. The
+decoherence is, in general, incomplete and strongly depends on the initial
+state of the qubit.",0807.4440v2
+2008-08-03,Superradiant Instability of Five-Dimensional Rotating Charged AdS Black Holes,"We study the instability of small AdS black holes with two independent
+rotation parameters in minimal five-dimensional gauged supergravity to massless
+scalar perturbations. We analytically solve the Klein-Gordon equation for
+low-frequency perturbations in two regions of the spacetime of these black
+holes: namely, in the region close to the horizon and in the far-region. By
+matching the solutions in an intermediate region, we calculate the frequency
+spectrum of quasinormal modes. We show that in the regime of superradiance only
+the modes of even orbital quantum number undergo negative damping, resulting in
+exponential growth of the amplitude. That is, the black holes become unstable
+to these modes. Meanwhile, the modes of odd orbital quantum number do not
+undergo any damping, oscillating with frequency-shifts. This is in contrast
+with the case of four-dimensional small Kerr-AdS black holes which exhibit the
+instability to all modes of scalar perturbations in the regime of
+superradiance.",0808.0280v3
+2008-08-15,Collective excitations in two-dimensional antiferromagnet in strong magnetic field,"We discuss spin-$\frac12$ two-dimensional (2D) Heisenberg antiferromagnet
+(AF) on a square lattice at T=0 in strong magnetic field H near its saturation
+value $H_c$. A perturbation approach is proposed to obtain spectrum of magnons
+with momenta not very close to AF vector in the leading order in small
+parameter $(H_c-H)/H_c$. We find that magnons are well-defined quasi-particles
+at $H>0.9H_c$ although the damping is quite large near the zone boundary. A
+characteristic rotonlike local minimum in the spectrum is observed at ${\bf
+k}=(\pi,0)$ accompanied by decrease of the damping near $(\pi,0)$. The
+suggested approach can be used in discussion of short-wavelength excitations in
+other 2D Bose gases of particles or quasi-particles.",0808.2127v3
+2008-09-09,Process tomography of field damping and measurement of Fock state lifetimes by quantum non-demolition photon counting in a cavity,"The relaxation of a quantum field stored in a high-$Q$ superconducting cavity
+is monitored by non-resonant Rydberg atoms. The field, subjected to repetitive
+quantum non-demolition (QND) photon counting, undergoes jumps between photon
+number states. We select ensembles of field realizations evolving from a given
+Fock state and reconstruct the subsequent evolution of their photon number
+distributions. We realize in this way a tomography of the photon number
+relaxation process yielding all the jump rates between Fock states. The damping
+rates of the $n$ photon states ($0\leq n \leq 7$) are found to increase
+linearly with $n$. The results are in excellent agreement with theory including
+a small thermal contribution.",0809.1511v1
+2008-10-01,Excitation of trapped oscillations in discs around black holes,"High-frequency quasi-periodic oscillations detected in the light curves of
+black hole candidates can, according to one model, be identified with
+hydrodynamic oscillations of the accretion disc. We describe a non-linear
+coupling mechanism, suggested by Kato, through which inertial waves trapped in
+the inner regions of accretion discs around black holes are excited. Global
+warping and/or eccentricity of the disc have a fundamental role in this
+coupling: they combine with trapped modes, generating negative energy waves,
+that are damped as they approach the inner edge of the disc or their corotation
+resonance. As a result of this damping, inertial oscillations are amplified. We
+calculate the resulting eigenfunctions and their growth rates.",0810.0116v1
+2008-10-09,Atomistic spin dynamics of the CuMn spin glass alloy,"We demonstrate the use of Langevin spin dynamics for studying dynamical
+properties of an archetypical spin glass system. Simulations are performed on
+CuMn (20% Mn) where we study the relaxation that follows a sudden quench of the
+system to the low temperature phase. The system is modeled by a Heisenberg
+Hamiltonian where the Heisenberg interaction parameters are calculated by means
+of first-principles density functional theory. Simulations are performed by
+numerically solving the Langevin equations of motion for the atomic spins. It
+is shown that dynamics is governed, to a large degree, by the damping parameter
+in the equations of motion and the system size. For large damping and large
+system sizes we observe the typical aging regime.",0810.1645v1
+2008-10-20,On the Existence of Exponentially Decreasing Solutions of the Nonlinear Landau Damping Problem,"In this paper we prove the existence of a large class of periodic solutions
+of the Vlasov-Poisson in one space dimension that decay exponentially as t goes
+to infinity. The exponential decay is well known for the linearized version of
+the Landau damping problem and it has been proved in [4] for a class of
+solutions of the Vlasov-Poisson system that behaves asymptotically as free
+streaming solutions and are sufficiently flat in the space of velocities. The
+results in this paper enlarge the class of possible asymptotic limits,
+replacing the fatness condition in [4] by a stability condition for the
+linearized problem.",0810.3456v2
+2008-10-22,Thermal (in)stability of type I collagen fibrils,"We measured Young's modulus at temperatures ranging from 20 to 100 ^{\circ}$C
+for a collagen fibril taken from rat's tendon. The hydration change under
+heating and the damping decrement were measured as well. At physiological
+temperatures $25-45^{\circ}$C Young's modulus decreases, which can be
+interpreted as instability of collagen. For temperatures between
+$45-80^{\circ}$C Young's modulus first stabilizes and then increases with
+decreasing the temperature. The hydrated water content and the damping
+decrement have strong maxima in the interval $70-80^{\circ}$C indicating on
+complex inter-molecular structural changes in the fibril. All these effects
+disappear after heat-denaturating the sample at $120^\circ$C. Our main result
+is a five-stage mechanism by which the instability of a single collagen at
+physiological temperatures is compensated by the interaction between collagen
+molecules within the fibril.",0810.4172v1
+2008-11-03,Ion thermal effects in oscillating multi-ion plasma sheath theory,"The effects of ion temperature are discussed in a two-ion electron plasma and
+for a model applicable to the oscillating sheath theory that has recently been
+much in the focus of researchers. The differences between the fluid and kinetic
+models have been pointed out, as well as the differences between the
+approximative kinetic description (which involves the expansion of the plasma
+dispersion function), and the exact kinetic description. It is shown that the
+approximative kinetic description, first, can not describe the additional
+acoustic mode which naturally exists in the plasma with an additional ion
+population with a finite temperature, and, second, it yields an inaccurate
+Landau damping of the bulk ion acoustic mode. The reasons for these two
+failures are described. In addition to this, a fluid model is presented that is
+capable of capturing both of these features that are missing in the
+approximative kinetic description, i.e., two (fast and slow) ion acoustic
+modes, and the corresponding Landau damping of both modes.",0811.0251v1
+2008-12-01,Self-Diffusion in 2D Dusty Plasma Liquids: Numerical Simulation Results,"We perform Brownian dynamics simulations for studying the self-diffusion in
+two-dimensional (2D) dusty plasma liquids, in terms of both mean-square
+displacement and velocity autocorrelation function (VAF). Super-diffusion of
+charged dust particles has been observed to be most significant at infinitely
+small damping rate $\gamma$ for intermediate coupling strength, where the
+long-time asymptotic behavior of VAF is found to be the product of $t^{-1}$ and
+$\exp{(-\gamma t)}$. The former represents the prediction of early theories in
+2D simple liquids and the latter the VAF of a free Brownian particle. This
+leads to a smooth transition from super-diffusion to normal diffusion, and then
+to sub-diffusion with an increase of the damping rate. These results well
+explain the seemingly contradictory scattered in recent classical molecular
+dynamics simulations and experiments of dusty plasmas.",0812.0338v3
+2008-12-11,Reduced nonlinear description of Farley-Buneman instability,"In the study on nonlinear wave-wave processes in an ionosphere and a
+magnetosphere usually the main attention is paid to investigation of plasma
+turbulence at well developed stage, when the wide spectrum of plasma wave is
+present. On the other side, it is well known that even if the number of
+cooperating waves remains small due to a competition of processes of their
+instability and attenuation, the turbulence appears in the result of their
+stochastic behavior. The regimes of nonlinear dynamics of low frequency waves
+excited due to Farley-Buneman instability in weakly ionized and inhomogeneous
+ionospheric plasma in the presence of electric current perpendicular to ambient
+magnetic field are considered. The problem is essentially three dimensional and
+difficult for full numerical simulation, but the strong collisional damping of
+waves allow to assume that in this case a perturbed state of plasma can be
+described as finite set of interacting waves, some of which are unstable and
+other strongly damping. The proposed nonlinear model allow to make full study
+of nonlinear stabilization, conditions of stochasticity and to consider the
+different regimes and properties of few mode plasma turbulence.",0812.2182v1
+2008-12-16,Reconstructing Baryon Oscillations: A Lagrangian Theory Perspective,"Recently Eisenstein and collaborators introduced a method to `reconstruct'
+the linear power spectrum from a non-linearly evolved galaxy distribution in
+order to improve precision in measurements of baryon acoustic oscillations. We
+reformulate this method within the Lagrangian picture of structure formation,
+to better understand what such a method does, and what the resulting power
+spectra are. We show that reconstruction does not reproduce the linear density
+field, at second order. We however show that it does reduce the damping of the
+oscillations due to non-linear structure formation, explaining the improvements
+seen in simulations. Our results suggest that the reconstructed power spectrum
+is potentially better modeled as the sum of three different power spectra, each
+dominating over different wavelength ranges and with different non-linear
+damping terms. Finally, we also show that reconstruction reduces the
+mode-coupling term in the power spectrum, explaining why mis-calibrations of
+the acoustic scale are reduced when one considers the reconstructed power
+spectrum.",0812.2905v3
+2009-01-28,Location- and observation time-dependent quantum-tunneling,"We investigate quantum tunneling in a translation invariant chain of
+particles. The particles interact harmonically with their nearest neighbors,
+except for one bond, which is anharmonic. It is described by a symmetric double
+well potential. In the first step, we show how the anharmonic coordinate can be
+separated from the normal modes. This yields a Lagrangian which has been used
+to study quantum dissipation. Elimination of the normal modes leads to a
+nonlocal action of Caldeira-Leggett type. If the anharmonic bond defect is in
+the bulk, one arrives at Ohmic damping, i.e. there is a transition of a
+delocalized bond state to a localized one if the elastic constant exceeds a
+critical value $C_{crit}$. The latter depends on the masses of the bond defect.
+Superohmic damping occurs if the bond defect is in the site $M$ at a finite
+distance from one of the chain ends. If the observation time $T$ is smaller
+than a characteristic time $\tau_M \sim M$, depending on the location M of the
+defect, the behavior is similar to the bulk situation. However, for $T \gg
+\tau_M$ tunneling is never suppressed.",0901.4518v1
+2009-02-16,Plasmon excitations in homogeneous neutron star matter,"We study the possible collective plasma modes which can affect neutron-star
+thermodynamics and different elementary processes in the baryonic density range
+between nuclear saturation ($\rho_0$) and $3\rho_0$. In this region, the
+expected constituents of neutron-star matter are mainly neutrons, protons,
+electrons and muons ($npe\mu$ matter), under the constraint of beta
+equilibrium. The elementary plasma excitations of the $pe\mu$ three-fluid
+medium are studied in the RPA framework. We emphasize the relevance of the
+Coulomb interaction among the three species, in particular the interplay of the
+electron and muon screening in suppressing the possible proton plasma mode,
+which is converted into a sound-like mode. The Coulomb interaction alone is
+able to produce a variety of excitation branches and the full spectral function
+shows a rich structure at different energy. The genuine plasmon mode is pushed
+at high energy and it contains mainly an electron component with a substantial
+muon component, which increases with density. The plasmon is undamped for not
+too large momentum and is expected to be hardly affected by the nuclear
+interaction. All the other branches, which fall below the plasmon, are damped
+or over-damped.",0902.2552v2
+2009-02-27,Monogamy Inequality and Residual Entanglement of Three Qubits under Decoherence,"Exploring an analytical expression for the convex roof of the pure state
+squared concurrence for rank 2 mixed states the entanglement of a system of
+three particles under decoherence is studied, using the monogamy inequality for
+mixed states and the residual entanglement obtained from it. The monogamy
+inequality is investigated both for the concurrence and the negativity in the
+case of local independent phase damping channel acting on generalized GHZ
+states of three particles and the local independent amplitude damping channel
+acting on generalized W state of three particles. It is shown that the
+bipartite entanglement between one qubit and the rest has a qualitative similar
+behavior to the entanglement between individual qubits, and that the residual
+entanglement in terms of the negativity cannot be a good entanglement measure
+for mixed states, since it can increase under local decoherence.",0903.0019v2
+2009-03-12,X-band crab cavities for the CLIC beam delivery system,"The CLIC machine incorporates a 20 mrad crossing angle at the IP to aid the
+extraction of spent beams. In order to recover the luminosity lost through the
+crossing angle a crab cavity is proposed to rotate the bunches prior to
+collision. The crab cavity is chosen to have the same frequency as the main
+linac (11.9942 GHz) as a compromise between size, phase stability requirements
+and beam loading. It is proposed to use a HE11 mode travelling wave structure
+as the CLIC crab cavity in order to minimise beam loading and mode separation.
+The position of the crab cavity close to the final focus enhances the effect of
+transverse wake-fields so effective wake-field damping is required. A damped
+detuned structure is proposed to suppress and de-cohere the wake-field hence
+reducing their effect. Design considerations for the CLIC crab cavity will be
+discussed as well as the proposed high power testing of these structures at
+SLAC.",0903.2116v1
+2009-03-16,Regularity of invariant sets in semilinear damped wave equations,"Under fairly general assumptions, we prove that every compact invariant
+subset $\mathcal I$ of the semiflow generated by the semilinear damped wave
+equation \epsilon u_{tt}+u_t+\beta(x)u-\sum_{ij}(a_{ij}
+(x)u_{x_j})_{x_i}&=f(x,u),&& (t,x)\in[0,+\infty[\times\Omega,
+u&=0,&&(t,x)\in[0,+\infty[\times\partial\Omega in $H^1_0(\Omega)\times
+L^2(\Omega)$ is in fact bounded in $D(\mathbf A)\times H^1_0(\Omega)$. Here
+$\Omega$ is an arbitrary, possibly unbounded, domain in $\R^3$, $\mathbf A
+u=\beta(x)u-\sum_{ij}(a_{ij}(x)u_{x_j})_{x_i}$ is a positive selfadjoint
+elliptic operator and $f(x,u)$ is a nonlinearity of critical growth. The
+nonlinearity $f(x,u)$ needs not to satisfy any dissipativeness assumption and
+the invariant subset $\mathcal I$ needs not to be an an attractor.",0903.2782v1
+2009-03-20,Hawking-Unruh radiation as irreversible consequence of radiative action in dynamics,"Hawking-Unruh thermal state of warm surrounding field encountered in
+non-inertial frames is shown to be a real phenomenon, a marker of nonstationary
+dynamic evolutions. In accelerated motion of a charged particle it is shown
+that the recoiled damping effect of Larmor radiation relaxation leads to
+distinctive thermal power, which is akin to that of Hawking-Unruh radiation
+from warm surrounding field of the accelerated charge. The damping effect from
+recoil-momentum of transverse electromagnetic field is worked out by
+considering torque imparted to the inherently existing angular evolution of
+spherically polarized vacuum field around the point-like charged particle in
+acceleration. Hawking-Unruh effects is generally noted to be a universal marker
+of decoherence in evolution in all scales of microscopic, macroscopic and
+megascopic systems. Besides detailing the case of electrodynamics, the various
+efficacies of H-U relaxation are considered in the nonstationary evolutions.",0903.3529v2
+2009-03-25,The covering factor of high redshift damped Lyman-$α$ systems,"We have used the Very Long Baseline Array to image 18 quasars with foreground
+damped Lyman-$\alpha$ systems (DLAs) at 327, 610 or 1420 MHz, to measure the
+covering factor $f$ of each DLA at or near its redshifted HI 21cm line
+frequency. Including six systems from the literature, we find that none of 24
+DLAs at $0.09 < z < 3.45$ has an exceptionally low covering factor, with $f
+\sim 0.45 - 1$ for the 14 DLAs at $z > 1.5$, $f \sim 0.41 - 1$ for the 10
+systems at $z < 1$, and consistent covering factor distributions in the two
+sub-samples. The observed paucity of detections of HI 21cm absorption in
+high-$z$ DLAs thus cannot be explained by low covering factors and is instead
+likely to arise due to a larger fraction of warm HI in these absorbers.",0903.4483v1
+2009-04-15,Size dependent Acoustic Phonon Dynamics of CdTe0.68Se0.32 Nanoparticles in Borosilicate glass,"Low frequency acoustic vibration and phonon linewidth for CdTe0.68Se0.32
+nanoparticle embedded in borosilicate glass are calculated using two different
+approaches by considering the elastic continuum model and fixed boundary
+condition. The presence of medium significantly affects the phonon peaks and
+results into the broadening of the modes. The linewidth is found to depend
+inversely on the size, similar to that reported experimentally. The damping
+time and quality factor have also been calculated. The damping time that is of
+the order of picoseconds decreases with the decrease in size. High value of
+quality factor for l=2 normal mode suggests the less loss of energy for this
+mode.",0904.2278v1
+2009-04-19,Incorporating Human Body Mass in Standards of Helmet Impact Protection against Traumatic Brain Injury,"Impact induced traumatic brain injury (ITBI) describes brain injury from head
+impact not necessarily accompanied by skull fracture. For sufficiently abrupt
+head impact decelerations, ITBI results from brain tissue stress incurred as
+the brain crashes into the inside of the skull wall, displacing the surrounding
+cerebral spinal fluid (CSF). Proper helmet cushioning can damp the impact force
+and reduce ITBI. But force is mass times acceleration and commonly used helmet
+blunt impact standards are based only on acceleration thresholds. Here I show
+how this implies that present standards overestimate the minimum acceleration
+onset for ITBI by implicitly assuming that the brain is mechanically decoupled
+from the body. I quantify how an arbitrary orientation of the body with respect
+to impact direction increases the effective mass that should be used in
+calculating the required damping force and injury threshold accelerations. I
+suggest a practical method to incorporate the body mass and impact angle into
+ITBI helmet standards and provide direction for further work.",0904.2856v1
+2009-04-21,Type II migration of planets on eccentric orbits,"The observed extrasolar planets possess both large masses (with a median M
+sin i of 1.65 MJ) and a wide range in orbital eccentricity (0 < e < 0.94). As
+planets are thought to form in circumstellar disks, one important question in
+planet formation is determining whether, and to what degree, a gaseous disk
+affects an eccentric planet's orbit. Recent studies have probed the interaction
+between a disk and a terrestrial planet on an eccentric orbit, and the
+interaction between a disk and a gas giant on a nearly circular orbit, but
+little is known about the interaction between a disk and an eccentric gas
+giant. Such a scenario could arise due to scattering while the disk is still
+present, or perhaps through planet formation via gravitational instability. We
+fill this gap with simulations of eccentric, massive (gap-forming) planets in
+disks using the hydrodynamical code FARGO. Although the long-term orbital
+evolution of the planet depends on disk properties, including the boundary
+conditions used, the disk always acts to damp eccentricity when the planet is
+released into the disk. This eccentricity damping takes place on a timescale of
+40 years, 15 times faster than the migration timescale.",0904.3336v1
+2009-05-13,J-transform applied to the detection of Gravitational Waves: preliminary results,"We propose to apply to the detection of Gravitational Waves a new method
+developed for the spectral analysis of noisy time-series of damped oscillators.
+  From the Pad\'e Approximations of the time-series Z-transform, a Jacobi
+Matrix (J-Matrix) is constructed. We show that the J-Matrix has bound states
+with eigenvalues strictly inside the unit circle. Each bound state can be
+identified with one precise damped oscillator. Beside these bound states, there
+is an essential spectrum sitting on the unit circle which represents the noise.
+In this picture, signal and noise are clearly separated and identified in the
+complex plane. Furthermore, we show that the J-transform enjoys the exceptional
+feature of lossless undersampling. We take advantage of the above properties of
+the J-transform to develop a procedure for the search of Gravitational Wave
+bursts in interferometric data series such as those of LIGO and VIRGO projects.
+Successful application of our procedure to simulated data having a poor signal
+to noise ratio, highlights the power of our method.",0905.2000v1
+2009-05-25,Non-Markovian dynamics of a biased qubit coupled to a structured bath,"A new analytical approach, beyond rotating wave approximation, based on
+unitary transformations and the non-Markovian master equation for the density
+operator, is applied to treat the biased spin boson model with a Lorentzian
+structured bath for arbitrary detunings at zero temperature. Compared to zero
+bias, we find that the dynamics demonstrates two more damping oscillation
+frequencies and one additional relaxation frequency for non-zero bias, where
+one of the damping oscillation frequencies is a new effect. Analytical
+expressions for the non-Markovian dynamics and the corresponding spectrum, the
+localized-delocalized transition point, the coherent-incoherent transition
+point, the analytical ground energy, the renormalized tunneling factor and the
+susceptibility are determined. The sum rule and the Shiba relation are checked
+in the coherent regime.",0905.3965v3
+2009-05-28,A black box method for solving the complex exponentials approximation problem,"A common problem, arising in many different applied contexts, consists in
+estimating the number of exponentially damped sinusoids whose weighted sum best
+fits a finite set of noisy data and in estimating their parameters. Many
+different methods exist to this purpose. The best of them are based on
+approximate Maximum Likelihood estimators, assuming to know the number of
+damped sinusoids, which can then be estimated by an order selection procedure.
+As the problem can be severely ill posed, a stochastic perturbation method is
+proposed which provides better results than Maximum Likelihood based methods
+when the signal-to-noise ratio is low. The method depends on some
+hyperparameters which turn out to be essentially independent of the
+application. Therefore they can be fixed once and for all, giving rise to a
+black box method.",0905.4602v2
+2009-06-10,GALEX Discovery of a Damped Ly-alpha System at Redshift z = 1,"We report the first discovery of a QSO damped Ly-alpha (DLA) system by the
+GALEX satellite. The system was initially identified as an MgII absorption-line
+system (z_abs=1.028) in the spectrum of SDSS QSO J0203-0910 (z_em=1.58). The
+presence of unusually strong absorption due to metal lines of ZnII, CrII, MnII,
+and FeII clearly suggested that it might be a DLA system with N{HI} > 2 x 10^20
+atoms cm^-2. Follow-up GALEX NUV grism spectroscopy confirms the system
+exhibits a DLA absorption line, with a measured HI column density of N{HI} =
+1.50+/-0.45 x 10^21 atoms cm^-2. By combining the GALEX N{HI} determination
+with the SDSS spectrum measurements of unsaturated metal-line absorption due to
+ZnII, which is generally not depleted onto grains, we find that the system's
+neutral-gas-phase metal abundance is [Zn/H] = -0.69+/-0.22, or ~20% solar. By
+way of comparison, although this system has one of the largest Zn^+ column
+densities, its metal abundances are comparable to other DLAs at z~1.
+Measurements of the abundances of Cr, Fe, and Mn help to further pin down the
+evolutionary state of the absorber.",0906.2018v1
+2009-06-11,Longitudinal Stability of Recycler Bunches; Part I: Thresholds for Loss of Landau Damping,"We examine the stability of intense flat bunches in barrier buckets used in
+the Recycler. We consider some common stationary distributions and show that
+they would be unstable against rigid dipole oscillations. We then discuss an
+analytical model for the line density that best describes measured bunch
+profiles. We include space charge in this model to predict the bunch intensity
+at which Landau damping would be lost. The dependence of this threshold on the
+bunch length is studied and related to the results of an experimental study
+with shorter bunch lengths. The threshold for the microwave instability is
+estimated. These studies will be followed by more detailed numerical studies.",0906.2188v1
+2009-06-15,Regge poles of the Schwarzschild black hole: a WKB approach,"We provide simple and accurate analytical expressions for the Regge poles of
+the Schwarzschild black hole. This is achieved by using third-order WKB
+approximations to solve the radial wave equations for spins 0, 1 and 2. These
+results permit us to obtain analytically the dispersion relation and the
+damping of the ""surface waves"" lying on the photon sphere of the Schwarzschild
+black hole and which generate the weakly damped quasinormal modes of its
+spectrum. Our results could be helpful in order to simplify considerably the
+description of wave scattering from the Schwarzschild black hole as well as the
+analysis of the gravitational radiation created in many black hole processes.
+Furthermore, the existence of dispersion relations for the photons propagating
+close to the photon sphere could have also important consequences in the
+context of gravitational lensing.",0906.2601v3
+2009-06-30,Cooling a magnetic resonance force microscope via the dynamical back-action of nuclear spins,"We analyze the back-action influence of nuclear spins on the motion of the
+cantilever of a magnetic force resonance microscope. We calculate the
+contribution of nuclear spins to the damping and frequency shift of the
+cantilever. We show that, at the Rabi frequency, the energy exchange between
+the cantilever and the spin system cools or heats the cantilever depending on
+the sign of the high-frequency detuning. We also show that the spin noise leads
+to a significant damping of the cantilever motion.",0906.5420v2
+2009-07-03,Magnetic interference patterns in long disordered Josephson junctions,"We study a diffusive superconductor - normal metal - superconductor (SNS)
+junction in an external magnetic field. In the limit of a long junction, we
+find that the form of the dependence of the Josephson current on the field and
+on the length of the junction depends on the ratio between the junction width
+and the length associated with the magnetic field. A certain critical ratio
+between these two length scales separates two different regimes. In narrow
+junctions, the critical current exhibits a pure decay as a function of the
+junction length or of the magnetic field. In wide junctions, the critical
+current exhibits damped oscillations as a function of the same parameters. This
+damped oscillating behavior differs from the Fraunhofer pattern typical for
+short or tunnel junctions. In wide and long junctions, superconducting pair
+correlations and supercurrent are localized along the edges of the junction.",0907.0632v3
+2009-07-12,Symmetries shape the current in ratchets induced by a bi-harmonic force,"Equations describing the evolution of particles, solitons, or localized
+structures, driven by a zero-average, periodic, external force, and invariant
+under time reversal and a half-period time shift, exhibit a ratchet current
+when the driving force breaks these symmetries. The bi-harmonic force
+$f(t)=\epsilon_1\cos(q \omega t+\phi_1)+\epsilon_2\cos(p\omega t+\phi_2)$ does
+it for almost any choice of $\phi_{1}$ and $\phi_{2}$, provided $p$ and $q$ are
+two co-prime integers such that $p+q$ is odd. It has been widely observed, in
+experiments in Josephson-junctions, photonic crystals, etc., as well as in
+simulations, that the ratchet current induced by this force has the shape
+$v\propto\epsilon_1^p\epsilon_2^q\cos(p \phi_{1} - q \phi_{2} + \theta_0)$ for
+small amplitudes, where $\theta_0$ depends on the damping ($\theta_0=\pi/2$ if
+there is no damping, and $\theta_0=0$ for overdamped systems). We rigorously
+prove that this precise shape can be obtained solely from the broken symmetries
+of the system and is independent of the details of the equation describing the
+system.",0907.2029v2
+2009-07-21,AFM Dissipation Topography of Soliton Superstructures in Adsorbed Overlayers,"In the atomic force microscope, the nanoscale force topography of even
+complex surface superstructures is extracted by the changing vibration
+frequency of a scanning tip. An alternative dissipation topography with similar
+or even better contrast has been demonstrated recently by mapping the
+(x,y)-dependent tip damping but the detailed damping mechanism is still
+unknown. Here we identify two different tip dissipation mechanisms: local
+mechanical softness and hysteresis. Motivated by recent data, we describe both
+of them in a onedimensional model of Moire' superstructures of incommensurate
+overlayers. Local softness at ""soliton"" defects yields a dissipation contrast
+that can be much larger than the corresponding density or corrugation contrast.
+At realistically low vibration frequencies, however, a much stronger and more
+effective dissipation is caused by the tip-induced nonlinear jumping of the
+soliton, naturally developing bistability and hysteresis. Signatures of this
+mechanism are proposed for experimental identification.",0907.3585v4
+2009-07-24,Harmonic damped oscillators with feedback. A Langevin study,"We consider a system in direct contact with a thermal reservoir and which, if
+left unperturbed, is well described by a memory-less equilibrium Langevin
+equation of the second order in the time coordinate. In such conditions, the
+strength of the noise fluctuations is set by the damping factor, in accordance
+with the Fluctuation and Dissipation theorem. We study the system when it is
+subject to a feedback mechanism, by modifying the Langevin equation
+accordingly. Memory terms now arise in the time evolution, which we study in a
+non-equilibrium steady state. Two types of feedback schemes are considered, one
+focusing on time shifts and one on phase shifts, and for both cases we evaluate
+the power spectrum of the system's fluctuations. Our analysis finds application
+in feedback cooled oscillators, such as the Gravitational Wave detector AURIGA.",0907.4309v1
+2009-08-19,Quantum Energy Teleportation with Electromagnetic Field: Discrete vs. Continuous Variables,"It is well known that usual quantum teleportation protocols cannot transport
+energy. Recently, new protocols called quantum energy teleportation (QET) have
+been proposed, which transport energy by local operations and classical
+communication with the ground states of many-body quantum systems. In this
+paper, we compare two different QET protocols for transporting energy with
+electromagnetic field. In the first protocol, a 1/2 spin (a qubit) is coupled
+with the quantum fluctuation in the vacuum state and measured in order to
+obtain one-bit information about the fluctuation for the teleportation. In the
+second protocol, a harmonic oscillator is coupled with the fluctuation and
+measured in order to obtain continuous-variable information about the
+fluctuation. In the spin protocol, the amount of teleported energy is
+suppressed by an exponential damping factor when the amount of input energy
+increases. This suppression factor becomes power damping in the case of the
+harmonic oscillator protocol. Therefore, it is concluded that obtaining more
+information about the quantum fluctuation leads to teleporting more energy.
+This result suggests a profound relationship between energy and quantum
+information.",0908.2674v2
+2009-08-25,Designing materials for plasmonic systems,"We use electronic structure calculations based upon density functional theory
+to search for ideal plasmonic materials among the alkali noble intermetallics.
+Importantly, we use density functional perturbation theory to calculate the
+electron-phonon interaction and from there use a first order solution to the
+Boltzmann equation to estimate the phenomenological damping frequency in the
+Drude dielectric function. We discuss the necessary electronic features of a
+plasmonic material and investigate the optical properties of the alkali-noble
+intermetallics in terms of some generic plasmonic system quality factors. We
+conclude that at low negative permittivities, KAu with a damping frequency of
+0.0224 eV and a high optical gap to bare plasma frequency ratio, outperforms
+gold and to some extent silver as a plasmonic material. Unfortunately, a low
+plasma frequency (1.54 eV) reduces its utility in modern plasmonics
+applications. We also discuss, briefly, the effect of local fields on the
+optical properties of these materials.",0908.3707v1
+2009-09-15,Quantum critical points of Helical Fermi Liquids,"Following our previous work, we study the quantum phase transitions which
+spontaneously develop ferromagnetic spin order in helical fermi liquids which
+breaks continuous spin-space rotation symmetry, with application to the edge
+states of 3d topological band insulators. With finite fermi surface, the
+critical point has both z = 3 over-damped and z = 2 propagating quantum
+critical modes, and the z = 3 mode will lead to non-fermi liquid behavior on
+the entire fermi surface. In the ordered phase, the Goldstone mode is
+over-damped unless it propagates along special directions, and quasiparticle is
+ill defined on most parts of the fermi surface except for special points.
+Generalizations of our results to other systems with spin-orbit couplings are
+also discussed.",0909.2647v3
+2009-09-25,Evidence for Landau's critical velocity in superfluid helium nanodroplets from wave packet dynamics of attached potassium dimers,"Femtosecond pump-probe spectroscopy has been used to study vibrational
+dynamics of potassium dimers attached to superfluid helium nanodroplets.
+Comparing the measured data with theoretical results based on dissipative
+quantum dynamics we propose that the most important effect of the helium
+environment is a general damping of the vibrational dynamics as a result of the
+interaction between dimer and collective degrees of freedom of the helium
+droplet. The calculations allow us to explain crucial experimental findings
+that are unobserved in gas-phase measurements. Remarkably, best agreement with
+experiment is found for a model where we neglect damping once a wave packet
+moves below a critical velocity. In this way the results provide first direct
+evidence for the Landau critical velocity in superfluid nanodroplets.",0909.4691v1
+2009-10-23,Fragmentation of the photoabsorption strength in neutral and charged metal microclusters,"The line shape of the plasma resonance in both neutral and charged small
+sodium clusters is calculated. The overall properties of the multipeak
+structure observed in the photoabsorption cross section of spherical Na_8 and
+Na_20 neutral clusters can be understood in terms of Landau damping. Quantal
+configurations are shown to play an important role. In the case of charged
+Na_9+ and Na_21^+ clusters a single peak is predicted that carries most of the
+oscillator strength.",0910.4576v1
+2009-10-28,Quantum Decoherence of Two Qubits,"It is commonly stated that decoherence in open quantum systems is due to
+growing entanglement with an environment. In practice, however, surprisingly
+often decoherence may equally well be described by random unitary dynamics
+without invoking a quantum environment at all. For a single qubit, for
+instance, pure decoherence (or phase damping) is always of random unitary type.
+Here, we construct a simple example of true quantum decoherence of two qubits:
+we present a feasible phase damping channel of which we show that it cannot be
+understood in terms of random unitary dynamics. We give a very intuitive
+geometrical measure for the positive distance of our channel to the convex set
+of random unitary channels and find remarkable agreement with the so-called
+Birkhoff defect based on the norm of complete boundedness.",0910.5364v1
+2009-10-29,System-reservoir dynamics of quantum and classical correlations,"We address the system-reservoir dynamics of classical and quantum
+correlations in the decoherence phenomenon, regarding a two qubit composite
+system interacting with two independent environments. The most common noise
+channels (amplitude damping, phase damping, bit flip, bit-phase flip, and phase
+flip) was studied. By analytical and numerical analysis we found that, contrary
+to what is usually stated in the literature, decoherence may occurs without
+entanglement between the system and the environment. We also found that, in
+some cases, the bipartite quantum correlation initially presented in the system
+is completely evaporated, it is not transferred to the environments.",0910.5711v3
+2009-11-04,Nonlinear damping in a micromechanical oscillator,"Nonlinear elastic effects play an important role in the dynamics of
+microelectromechanical systems (MEMS). Duffing oscillator is widely used as an
+archetypical model of mechanical resonators with nonlinear elastic behavior. In
+contrast, nonlinear dissipation effects in micromechanical oscillators are
+often overlooked. In this work, we consider a doubly clamped micromechanical
+beam oscillator, which exhibits nonlinearity in both elastic and dissipative
+properties. The dynamics of the oscillator is measured in frequency domain and
+time domain and compared to theoretical predictions based on Duffing-like model
+with nonlinear dissipation. We especially focus on the behavior of the system
+near bifurcation points. The results show that nonlinear dissipation can have a
+significant impact on the dynamics of micromechanical systems. To account for
+the results, we have developed a continuous model of a nonlinear viscoelastic
+string with Voigt-Kelvin dissipation relation, which shows a relation between
+linear and nonlinear damping. However, the experimental results suggest that
+this model alone cannot fully account for all the experimentally observed
+nonlinear dissipation, and that additional nonlinear dissipative processes
+exist in our devices.",0911.0833v2
+2009-11-04,Solar-like oscillations in massive main-sequence stars. I. Asteroseismic signatures of the driving and damping regions,"Motivated by the recent detection of stochastically excited modes in the
+massive star V1449 Aql (Belkacem et al., 2009b), already known to be a $\beta$
+Cephei, we theoretically investigate the driving by turbulent convection. By
+using a full non-adiabatic computation of the damping rates, together with a
+computation of the energy injection rates, we provide an estimate of the
+amplitudes of modes excited by both the convective region induced by the iron
+opacity bump and the convective core. Despite uncertainties in the dynamical
+properties of such convective regions, we demonstrate that both are able to
+efficiently excite $p$ modes above the CoRoT observational threshold and the
+solar amplitudes. In addition, we emphasise the potential asteroseismic
+diagnostics provided by each convective region, which we hope will help to
+identify the one responsible for solar-like oscillations, and to give
+constraints on this convective zone. A forthcoming work will be dedicated to an
+extended investigation of the likelihood of solar-like oscillations across the
+Hertzsprung-Russell diagram.",0911.0908v1
+2009-12-10,Bipartite quantum channels using multipartite cluster-type entangled coherent states,"We propose a particular encoding for bipartite entangled states derived from
+multipartite cluster-type entangled coherent states (CTECSs). We investigate
+the effects of amplitude damping on the entanglement content of this bipartite
+state, as well as its usefulness as a quantum channel for teleportation. We
+find interesting relationships among the amplitude of the coherent states
+constituting the CTECSs, the number of subsystems forming the logical qubits
+(redundancy), and the extent to which amplitude damping affects the
+entanglement of the channel. For instance, in the sense of sudden death of
+entanglement, given a fixed value of the initial coherent state amplitude, the
+entanglement life span is shortened if redundancy is increased.",0912.1949v2
+2009-12-18,Oscillatory transient regime in the forced dynamics of a spin torque nano-oscillator,"We demonstrate that the transient non-autonomous dynamics of a spin torque
+nano-oscillator (STNO) under a radio-frequency (rf) driving signal is
+qualitatively different from the dynamics described by the Adler model. If the
+external rf current $I_{rf}$ is larger than a certain critical value $I_{cr}$
+(determined by the STNO bias current and damping) strong oscillations of the
+STNO power and phase develop in the transient regime. The frequency of these
+oscillations increases with $I_{rf}$ as $\propto\sqrt{I_{rf} - I_{cr}}$ and can
+reach several GHz, whereas the damping rate of the oscillations is almost
+independent of $I_{rf}$. This oscillatory transient dynamics is caused by the
+strong STNO nonlinearity and should be taken into account in most STNO rf
+applications.",0912.3650v1
+2009-12-19,Study of sdO models: mode trapping,"We present the first description of mode trapping for sdO models. Mode
+trapping of gravity modes caused by the He/H chemical transition is found for a
+particular model, providing a selection effect for high radial order trapped
+modes. Low- and intermediate-radial order {\em p}-modes (mixed modes with a
+majority of nodes in the P-mode region) are found to be trapped by the C-O/He
+transition, but with no significant effects on the driving. This region seems
+to have also a subtle effect on the trapping of low radial order {\em g}-modes
+(mixed modes with a majority of nodes in the G-mode region), but again with no
+effect on the driving. We found that for mode trapping to have an influence on
+the driving of sdO modes (1) the mode should be trapped in a way that the
+amplitude of the eigenfunctions is lower in a damping region and (2) in this
+damping region significant energy interchange has to be produced.",0912.3911v1
+2009-12-20,Optimal Design of Fuzzy Based Power System Stabilizer Self Tuned by Robust Search Algorithm,"In the interconnected power system network, instability problems are caused
+mainly by the low frequency oscillations of 0.2 to 2.5 Hz. The supplementary
+control signal in addition with AVR and high gain excitation systems are
+provided by means of Power System Stabilizer (PSS). Conventional power system
+stabilizers provide effective damping only on a particular operating point. But
+fuzzy based PSS provides good damping for a wide range of operating points. The
+bottlenecks faced in designing a fuzzy logic controller can be minimized by
+using appropriate optimization techniques like Genetic Algorithm, Particle Swam
+Optimization, Ant Colony Optimization etc.In this paper the membership
+functions of FLC are optimized by the new breed optimization technique called
+Genetic Algorithm. This design methodology is implemented on a Single Machine
+Infinite Bus (SMIB) system. Simulation results on SMIB show the effectiveness
+and robustness of the proposed PSS over a wide range of operating conditions
+and system configurations.",0912.3960v2
+2009-12-23,Decoherence and Entanglement Dynamics in Fluctuating Fields,"We study pure phase damping of two qubits due to fluctuating fields. As
+frequently employed, decoherence is thus described in terms of random unitary
+(RU) dynamics, i.e., a convex mixture of unitary transformations. Based on a
+separation of the dynamics into an average Hamiltonian and a noise channel, we
+are able to analytically determine the evolution of both entanglement and
+purity. This enables us to characterize the dynamics in a concurrence-purity
+(CP) diagram: we find that RU phase damping dynamics sets constraints on
+accessible regions in the CP plane. We show that initial state and dynamics
+contribute to final entanglement independently.",0912.4654v2
+2010-01-02,Distinguishing quantum channels via magic squares game,"We study the effect of quantum memory in magic squares game when played in
+quantum domain. We consider different noisy quantum channels and analyze their
+influence on the magic squares quantum pseudo-telepathy game. We show that the
+probability of success can be used to distinguish the quantum channels. It is
+seen that the mean success probability decreases with increase of quantum
+noise. Where as the mean success probability increases with increase of quantum
+memory. It is also seen that the behaviour of amplitude damping and phase
+damping channels is similar. On the other hand, the behaviour of depolarizing
+channel is similar to the flipping channels. Therefore, the probability of
+success of the game can be used to distinguish the quantum channels.",1001.0295v1
+2010-01-06,Freezing of spin dynamics and omega/T scaling in underdoped cuprates,"The memory function approach to spin dynamics in doped antiferromagnetic
+insulator combined with the assumption of temperature independent static spin
+correlations and constant collective mode damping leads to omega/T scaling in a
+broad range. The theory involving a non universal scaling parameter is used to
+analyze recent inelastic neutron scattering results for underdoped cuprates.
+Adopting modified damping function also the emerging central peak in low-doped
+cuprates at low temperatures can be explained within the same framework.",1001.0837v1
+2010-01-15,Calculating Green Functions from Finite Systems,"In calculating Green functions for interacting quantum systems numerically
+one often has to resort to finite systems which introduces a finite size level
+spacing. In order to describe the limit of system size going to infinity
+correctly, one has to introduce an artificial broadening larger than the finite
+size level discretization. In this work we compare various discretization
+schemes for impurity problems, i.e. a small system coupled to leads. Starting
+from a naive linear discretization we will then discuss the logarithmic
+discretization of the Wilson NRG, compare it to damped boundary conditions and
+arbitrary discretization in energy space. We then discuss the importance of
+choosing the right single particle basis when calculating bulk spectral
+functions. Finally we show the influence of damped boundary conditions on the
+time evolution of wave packets leading to a NRG-tsunami.",1001.2750v1
+2010-02-02,Inertial Oscillations of Pinned Dislocations,"Dislocation pinning plays a vital role in the plastic behaviour of a
+crystalline solid. Here we report the first observation of the damped
+oscillations of a mobile dislocation after it gets pinned at an obstacle in the
+presence of a constant static shear load. These oscillations are found to be
+inertial, instead of forced as obtained in the studies of internal friction of
+solid. The rate of damping enables us to determine the effective mass of the
+dislocation. Nevertheless, the observed relation between the oscillation
+frequency and the link length is found to be anomalous, when compared with the
+theoretical results in the framework of Koehler's vibrating string model. We
+assign this anomaly to the improper boundary conditions employed in the
+treatment. Finally, we propose that the inertial oscillations may offer a
+plausible explanation of the electromagnetic emissions during material
+deformation and seismic activities.",1002.0422v1
+2010-02-03,Nonlinear stability of viscous roll waves,"Extending results of Oh--Zumbrun and Johnson--Zumbrun for parabolic
+conservation laws, we show that spectral stability implies nonlinear stability
+for spatially periodic viscous roll wave solutions of the one-dimensional St.
+Venant equations for shallow water flow down an inclined ramp. The main new
+issues to be overcome are incomplete parabolicity and the nonconservative form
+of the equations, which leads to undifferentiated quadratic source terms that
+cannot be handled using the estimates of the conservative case. The first is
+resolved by treating the equations in the more favorable Lagrangian
+coordinates, for which one can obtain large-amplitude nonlinear damping
+estimates similar to those carried out by Mascia--Zumbrun in the related shock
+wave case, assuming only symmetrizability of the hyperbolic part. The second is
+resolved by the observation that, similarly as in the relaxation and detonation
+cases, sources occurring in nonconservative components experience greater than
+expected decay, comparable to that experienced by a differentiated source.",1002.0788v2
+2010-02-09,Fate of non-Fermi liquid behavior in QED$_{3}$ at finite chemical potential,"The damping rate of two-dimensional massless Dirac fermions exhibit non-Fermi
+liquid behavior, $\propto \epsilon^{1/2}$, due to gauge field at zero
+temperature and zero chemical potential. We study the fate of this behavior at
+finite chemical potential. We fist calculate explicitly the temporal and
+spatial components of vacuum polarization functions. The analytical expressions
+imply that the temporal component of gauge field develops a static screening
+length at finite chemical potential while the transverse component remains
+long-ranged owing to gauge invariance. We then calculate the fermion damping
+rate and show that the temporal gauge field leads to normal Fermi liquid
+behavior but the transverse gauge field leads to non-Fermi liquid behavior
+$\propto \epsilon^{2/3}$ at zero temperature. This energy-dependence is more
+regular than $\propto \epsilon^{1/2}$ and does not change as chemical potential
+varies.",1002.1760v3
+2010-02-18,Direct Evidence for Two-Fluid Effects in Molecular Clouds,"We present a combination of theoretical and simulation-based examinations of
+the role of two-fluid ambipolar drift on molecular line widths. The dissipation
+provided by ion-neutral interactions can produce a significant difference
+between the widths of neutral molecules and the widths of ionic species,
+comparable to the sound speed. We demonstrate that Alfven waves and certain
+families of magnetosonic waves become strongly damped on scales comparable to
+the ambipolar diffusion scale. Using the RIEMANN code, we simulate two-fluid
+turbulence with ionization fractions ranging from 10^{-2} to 10^{-6}. We show
+that the wave damping causes the power spectrum of the ion velocity to drop
+below that of the neutral velocity when measured on a relative basis. Following
+a set of motivational observations by Li & Houde (2008), we produce synthetic
+line width-size relations that shows a difference between the ion and neutral
+line widths, illustrating that two-fluid effects can have an observationally
+detectable role in modifying the MHD turbulence in the clouds.",1002.3443v1
+2010-03-08,Potential mechanical loss mechanisms in bulk materials for future gravitational wave detectors,"Low mechanical loss materials are needed to further decrease thermal noise in
+upcoming gravitational wave detectors. We present an analysis of the
+contribution of Akhieser and thermoelastic damping on the experimental results
+of resonant mechanical loss measurements. The combination of both processes
+allows the fit of the experimental data of quartz in the low temperature region
+(10 K to 25 K). A fully anisotropic numerical calculation over a wide
+temperature range (10 K to 300 K) reveals, that thermoelastic damping is not a
+dominant noise source in bulk silicon samples. The anisotropic numerical
+calculation is sucessfully applied to the estimate of thermoelastic noise of an
+advanced LIGO sized silicon test mass.",1003.1613v1
+2010-04-08,Doppler cooling a microsphere,"Doppler cooling the center-of-mass motion of an optically levitated
+microsphere via the velocity dependent scattering force from narrow whispering
+gallery mode (WGM) resonances is described. Light that is red detuned from the
+WGM resonance can be used to damp the center-of-mass motion in a process
+analogous to the Doppler cooling of atoms. Leakage of photons out of the
+microsphere when the incident field is near resonant with the narrow WGM
+resonance acts to damp the motion of the sphere. The scattering force is not
+limited by saturation, but can be controlled by the incident power. Cooling
+times on the order of seconds are calculated for a 20 micron diameter silica
+microsphere trapped within optical tweezers, with a Doppler temperature limit
+in the microKelvin regime.",1004.1443v1
+2010-05-17,Concerning the statistics of cosmic magnetism,"Magnetic fields appear to be a generic feature of the early universe and are
+a natural source of secondary CMB non-Gaussianity. In recent years the
+statistical nature of the stresses of a primordial magnetic field has been well
+studied. In this paper we confirm and extend these studies at one- and
+two-point level, and present analytical results for a wide range of power-law
+spectra. We also consider two non-power law cases of interest: a blue spectrum
+with an extended damping tail on small scales, which could be generated by the
+non-linear mixing of density and vorticity; and a red spectrum with a damping
+tail on large scales. We then briefly consider the CMB impacts that result from
+such fields. While this paper focuses on the one- and two-point moments, the
+techniques we employ are designed to ease the analysis of the full bispectra
+induced by primordial magnetic fields.",1005.2982v1
+2010-05-20,Line Solutions for the Euler and Euler-Poisson Equations with Multiple Gamma Law,"In this paper, we study the Euler and Euler-Poisson equations in $R^{N}$,
+with multiple $\gamma$-law for pressure function: \begin{equation}
+P(\rho)=e^{s}\sum_{j=1}^{m}\rho^{\gamma_{j}}, \end{equation} where all
+$\gamma_{i+1}>\gamma_{i}\geq1$, is the constants. The analytical line solutions
+are constructed for the systems. It is novel to discover the analytical
+solutions to handle the systems with mixed pressure function. And our solutions
+can be extended to the systems with the generalized multiple damping and
+pressure function.",1005.3651v1
+2010-06-12,Mechanical filtering in forced-oscillation of two coupled pendulums,"Forced oscillation of a system composed of two pendulums coupled by a spring
+in the presence of damping is investigated. In the steady state and within the
+small angle approximation we solve the system equations of motion and obtain
+the amplitudes and phases of in terms of the frequency of the sinusoidal
+driving force. The resonance frequencies are obtained and the amplitude ratio
+is discussed in details. Contrary to a single oscillator, in this two-degree of
+freedom system four resonant frequencies, which are close to mode frequencies,
+appear. Within the pass-band interval the system is shown to exhibit a rich and
+complicated behaviour. It is shown that damping crucially affects the system
+properties. Under certain circumstances, the amplitude of the oscillator which
+is directly connected to the driving force becomes smaller than the one far
+from it. Particularly we show the existence of a driving frequency at which the
+connected oscillator's amplitude goes zero.",1006.2475v1
+2010-07-12,Ferromagnetic Excitations in La$_{0.82}$Sr$_{0.18}$CoO$_{3}$ Observed Using Neutron Inelastic Scattering,"Polarized neutron inelastic scattering has been used to measure spin
+excitations in ferromagnetic La$_{0.82}$Sr$_{0.18}$CoO$_{3}$. The magnon
+spectrum of these spin excitations is well defined at low energies but becomes
+heavily damped at higher energies, and can be modeled using a quadratic
+dispersion. We determined a spin wave stiffness constant of $D=94\pm
+3$\,meV\,\AA$^{2}$. Assuming a nearest-neighbor Heisenberg model we find
+reasonable agreement between the exchange determined from D and the bulk Curie
+temperature. Several possible mechanisms to account for the observed spin-wave
+damping are discussed.",1007.1919v1
+2010-07-28,Minimization of phonon-tunneling dissipation in mechanical resonators,"Micro- and nanoscale mechanical resonators have recently emerged as
+ubiquitous devices for use in advanced technological applications, for example
+in mobile communications and inertial sensors, and as novel tools for
+fundamental scientific endeavors. Their performance is in many cases limited by
+the deleterious effects of mechanical damping. Here, we report a significant
+advancement towards understanding and controlling support-induced losses in
+generic mechanical resonators. We begin by introducing an efficient numerical
+solver, based on the ""phonon-tunneling"" approach, capable of predicting the
+design-limited damping of high-quality mechanical resonators. Further, through
+careful device engineering, we isolate support-induced losses and perform the
+first rigorous experimental test of the strong geometric dependence of this
+loss mechanism. Our results are in excellent agreement with theory,
+demonstrating the predictive power of our approach. In combination with recent
+progress on complementary dissipation mechanisms, our phonon-tunneling solver
+represents a major step towards accurate prediction of the mechanical quality
+factor.",1007.4948v1
+2010-08-05,Linear and Non-Linear Landau Resonance of Kinetic Alfvén Waves: Consequences for Electron Distribution and Wave Spectrum in the Solar Wind,"Kinetic Alfven wave turbulence in solar wind is considered and it is shown
+that non-Maxwellian electron distribution function has a significant effect on
+the dynamics of the solar wind plasmas. Linear Landau damping leads to the
+formation of a plateau in the parallel electron distribution function which
+diminishes the Landau damping rate significantly. Nonlinear scattering of waves
+by plasma particles is generalized to short wavelengths and it is found that
+for the solar wind parameters this scattering is the dominant process as
+compared to three wave decay and coalescence in the wave vector range .
+Incorporation of these effects lead to the steepening of the wave spectrum
+between the inertial and the dissipation ranges with a spectral index between 2
+and 3. This region can be labeled as the scattering range. Such steepening has
+been observed in the solar wind plasmas.",1008.0993v1
+2010-08-11,Theory for a dissipative droplet soliton excited by a spin torque nanocontact,"A novel type of solitary wave is predicted to form in spin torque oscillators
+when the free layer has a sufficiently large perpendicular anisotropy. In this
+structure, which is a dissipative version of the conservative droplet soliton
+originally studied in 1977 by Ivanov and Kosevich, spin torque counteracts the
+damping that would otherwise destroy the mode. Asymptotic methods are used to
+derive conditions on perpendicular anisotropy strength and applied current
+under which a dissipative droplet can be nucleated and sustained. Numerical
+methods are used to confirm the stability of the droplet against various
+perturbations that are likely in experiments, including tilting of the applied
+field, non-zero spin torque asymmetry, and non-trivial Oersted fields. Under
+certain conditions, the droplet experiences a drift instability in which it
+propagates away from the nanocontact and is then destroyed by damping.",1008.1898v1
+2010-08-18,Modulation stabilization of Bloch oscillations of two-component Bose-Einstein condensates in optical lattices,"We study the Bloch oscillations (BOs) of two-component Bose-Einstein
+condensates (BECs) trapped in spin-dependent optical lattices. Based on the
+derived equations of motion of the wave packet in the basis of localized wave
+functions of the lattice sites, the damping effect induced by the
+intercomponent and intracomponent interactions to the BOs is explored
+analytically and numerically. We also show that such damping of the BOs can be
+suppressed entirely if all the atom-atom interactions are modulated
+synchronously and harmonically in time with suitable frequency via the Feshbach
+resonance. When the intercomponent and the intracomponent interactions have
+inverse signs, we find that the long-living BOs and even the revival of the BOs
+can be achieved via only statically modulating the configuration of optical
+lattices. The results provide a valuable guidance for achieving long-living BOs
+in the two-component BEC system by the Feshbach resonances and manipulating the
+configuration of the optical lattices.",1008.3004v1
+2010-08-19,Josephson Coupling and Fiske Dynamics in Ferromagnetic Tunnel Junctions,"We report on the fabrication of Nb/AlO_x/Pd_{0.82}Ni_{0.18}/Nb
+superconductor/insulator/ferromagnetic metal/superconductor (SIFS) Josephson
+junctions with high critical current densities, large normal resistance times
+area products, high quality factors, and very good spatial uniformity. For
+these junctions a transition from 0- to \pi-coupling is observed for a
+thickness d_F ~ 6 nm of the ferromagnetic Pd_{0.82}Ni_{0.18} interlayer. The
+magnetic field dependence of the \pi-coupled junctions demonstrates good
+spatial homogeneity of the tunneling barrier and ferromagnetic interlayer.
+Magnetic characterization shows that the Pd_{0.82}Ni_{0.18} has an out-of-plane
+anisotropy and large saturation magnetization, indicating negligible dead
+layers at the interfaces. A careful analysis of Fiske modes provides
+information on the junction quality factor and the relevant damping mechanisms
+up to about 400 GHz. Whereas losses due to quasiparticle tunneling dominate at
+low frequencies, the damping is dominated by the finite surface resistance of
+the junction electrodes at high frequencies. High quality factors of up to 30
+around 200 GHz have been achieved. Our analysis shows that the fabricated
+junctions are promising for applications in superconducting quantum circuits or
+quantum tunneling experiments.",1008.3341v1
+2010-09-03,A Simple Numerical Absorbing Layer Method in Elastodynamics,"The numerical analysis of elastic wave propagation in unbounded media may be
+difficult to handle due to spurious waves reflected at the model artificial
+boundaries. Several sophisticated techniques such as nonreflecting boundary
+conditions, infinite elements or absorbing layers (e.g. Perfectly Matched
+Layers) lead to an important reduction of such spurious reflections. In this
+Note, a simple and efficient absorbing layer method is proposed in the
+framework of the Finite Element Method. This method considers Rayleigh/Caughey
+damping in the absorbing layer and its principle is presented first. The
+efficiency of the method is then shown through 1D Finite Element simulations
+considering homogeneous and heterogeneous damping in the absorbing layer. 2D
+models are considered afterwards to assess the efficiency of the absorbing
+layer method for various wave types (surface waves, body waves) and incidences
+(normal to grazing). The method is shown to be efficient for different types of
+elastic waves and may thus be used for various elastodynamic problems in
+unbounded domains.",1009.0592v1
+2010-09-09,Modulation of waves due to charge-exchange collisions in magnetized partially ionized space plasma,"A nonlinear time dependent fluid simulation model is developed that describes
+the evolution of magnetohydrodynamic waves in the presence of collisional and
+charge exchange interactions of a partially ionized plasma. The partially
+ionized plasma consists of electrons, ions and a significant number of neutral
+atoms. In our model, the electrons and ions are described by a single fluid
+compressible magnetohydrodynamic (MHD) model and are coupled self-consistently
+to the neutral gas, described by the compressible hydrodynamic equations. Both
+the plasma and neutral fluids are treated with different energy equations that
+describe thermal energy exchange processes between them. Based on our
+self-consistent model, we find that propagating Alfv\'enic and fast/slow modes
+grow and damp alternately through a nonlinear modulation process. The
+modulation appears to be robust and survives strong damping by the neutral
+component.",1009.1859v1
+2010-09-15,A discontinuous Galerkin method for the Vlasov-Poisson system,"A discontinuous Galerkin method for approximating the Vlasov-Poisson system
+of equations describing the time evolution of a collisionless plasma is
+proposed. The method is mass conservative and, in the case that piecewise
+constant functions are used as a basis, the method preserves the positivity of
+the electron distribution function and weakly enforces continuity of the
+electric field through mesh interfaces and boundary conditions. The performance
+of the method is investigated by computing several examples and error estimates
+associated system's approximation are stated. In particular, computed results
+are benchmarked against established theoretical results for linear advection
+and the phenomenon of linear Landau damping for both the Maxwell and Lorentz
+distributions. Moreover, two nonlinear problems are considered: nonlinear
+Landau damping and a version of the two-stream instability are computed. For
+the latter, fine scale details of the resulting long-time BGK-like state are
+presented. Conservation laws are examined and various comparisons to theory are
+made. The results obtained demonstrate that the discontinuous Galerkin method
+is a viable option for integrating the Vlasov-Poisson system.",1009.3046v2
+2010-10-03,Measurement of damping and temperature: Precision bounds in Gaussian dissipative channels,"We present a comprehensive analysis of the performance of different classes
+of Gaussian states in the estimation of Gaussian phase-insensitive dissipative
+channels. In particular, we investigate the optimal estimation of the damping
+constant and reservoir temperature. We show that, for two-mode squeezed vacuum
+probe states, the quantum-limited accuracy of both parameters can be achieved
+simultaneously. Moreover, we show that for both parameters two-mode squeezed
+vacuum states are more efficient than either coherent, thermal or single-mode
+squeezed states. This suggests that at high energy regimes two-mode squeezed
+vacuum states are optimal within the Gaussian setup. This optimality result
+indicates a stronger form of compatibility for the estimation of the two
+parameters. Indeed, not only the minimum variance can be achieved at fixed
+probe states, but also the optimal state is common to both parameters.
+Additionally, we explore numerically the performance of non-Gaussian states for
+particular parameter values to find that maximally entangled states within
+D-dimensional cutoff subspaces perform better than any randomly sampled states
+with similar energy. However, we also find that states with very similar
+performance and energy exist with much less entanglement than the maximally
+entangled ones.",1010.0442v1
+2010-10-12,Movers and shakers: Granular damping in microgravity,"The response of an oscillating granular damper to an initial perturbation is
+studied using experiments performed in microgravity and granular dynamics
+mulations. High-speed video and image processing techniques are used to extract
+experimental data. An inelastic hard sphere model is developed to perform
+simulations and the results are in excellent agreement with the experiments.
+The granular damper behaves like a frictional damper and a linear decay of the
+amplitude is bserved. This is true even for the simulation model, where
+friction forces are absent. A simple expression is developed which predicts the
+optimal damping conditions for a given amplitude and is independent of the
+oscillation frequency and particle inelasticities.",1010.2343v1
+2010-10-18,"K-shell photoionization of Na-like to Cl-like ions of Mg, Si, S, Ar, and Ca","We present $R$-matrix calculations of photoabsorption and photoionization
+cross sections across the K-edge of Mg, Si, S, Ar, and Ca ions with more than
+10 electrons. The calculations include the effects of radiative and Auger
+damping by means of an optical potential. The wave functions are constructed
+from single-electron orbital bases obtained using a Thomas--Fermi--Dirac
+statistical model potential. Configuration interaction is considered among all
+states up to $n=3$. The damping processes affect the resonances converging to
+the K-thresholds causing them to display symmetric profiles of constant width
+that smear the otherwise sharp edge at the photoionization threshold. These
+data are important for modeling of features found in photoionized plasmas.",1010.3734v1
+2010-10-19,A possible signature of cosmic neutrino decoupling in the nHz region of the spectrum of primordial gravitational waves,"In this paper we study the effect of cosmic neutrino decoupling on the
+spectrum of cosmological gravitational waves (GWs). At temperatures T>>1 MeV,
+neutrinos constitute a perfect fluid and do not hinder GW propagation, while
+for T<<1 MeV they free-stream and have an effective viscosity that damps
+cosmological GWs by a constant amount. In the intermediate regime,
+corresponding to neutrino decoupling, the damping is frequency-dependent. GWs
+entering the horizon during neutrino decoupling have a frequency f ~ 1 nHz,
+corresponding to a frequency region that will be probed by Pulsar Timing Arrays
+(PTAs). In particular, we show how neutrino decoupling induces a spectral
+feature in the spectrum of cosmological GWs just below 1 nHz. We briefly
+discuss the conditions for a detection of this feature and conclude that it is
+unlikely to be observed by PTAs.",1010.3849v2
+2010-10-20,"Modified Landau levels, damped harmonic oscillator and two-dimensional pseudo-bosons","In a series of recent papers one of us has analyzed in some details a class
+of elementary excitations called {\em pseudo-bosons}. They arise from a special
+deformation of the canonical commutation relation $[a,a^\dagger]=\1$, which is
+replaced by $[a,b]=\1$, with $b$ not necessarily equal to $a^\dagger$. Here,
+after a two-dimensional extension of the general framework, we apply the theory
+to a generalized version of the two-dimensional Hamiltonian describing Landau
+levels. Moreover, for this system, we discuss coherent states and we deduce a
+resolution of the identity. We also consider a different class of examples
+arising from a classical system, i.e. a damped harmonic oscillator.",1010.4221v1
+2010-11-16,Forcibly driven coherent soft phonons in GeTe with intense THz-rate pump fields,"We propose an experimental technique to generate large amplitude coherent
+phonons with irradiation of THz-rate pump pulses and to study the dynamics of
+phase transition in GeTe ferroelectrics. When a single pump pulse irradiates
+the sample at various pump power densities, the frequency of the soft phonon
+decreases sub-linearly and saturates at higher pump powers. By contrast, when
+THz-rate pump pulse sequence irradiates the sample at matched time intervals to
+forcibly drive the oscillation, a large red-shift of the phonon frequency is
+observed without saturation effects. After excitation with a four pump pulse
+sequence, the coherent soft phonon becomes strongly damped leading to a near
+critical damping condition. This condition indicates that the lattice is driven
+to a precursor state of the phase transition.",1011.3624v2
+2010-11-21,Regular and chaotic transport of discrete solitons in asymmetric potentials,"Ratchet dynamics of topological solitons of the forced and damped discrete
+double sine-Gordon system are studied. Directed transport occurring both in
+regular and in chaotic regions of the phase space and its dependence on
+damping, amplitude and frequency of the driving, asymmetry parameter, coupling
+constant, has been extensively investigated. We show that the passage from
+ratchet phase-locked regime to chaotic ratchets occurs via a period doubling
+route to chaos and that, quite surprisingly, pinned states can exist inside
+phase-locking and chaotic transport regions for intermediate values of the
+coupling constant. The possibility to control chaotic discrete soliton ratchets
+by means of both small subharmonic signals and more general periodic drivings,
+has also been investigated.",1011.4707v1
+2010-11-26,Dependence of entanglement on initial states under amplitude damping channel in non-inertial frames,"Under amplitude damping channel, the dependence of the entanglement on the
+initial states $|\Theta>_{1}$ and $|\Theta>_{2}$, which reduce to four
+orthogonal Bell states if we take the parameter of states $\alpha=\pm
+1/\sqrt{2}$ are investigated. We find that the entanglements for different
+initial states will decay along different curves even with the same
+acceleration and parameter of the states. We note that, in an inertial frame,
+the sudden death of the entanglement for $|\Theta>_{1}$ will occur if
+$\alpha>1/\sqrt{2}$, while it will not take place for $|\Theta>_{2}$ for any
+$\alpha$. We also show that the possible range of the sudden death of the
+entanglement for $|\Theta>_{1}$ is larger than that for $|\Theta>_{2}$. There
+exist two groups of Bell state here we can't distinguish only by concurrence.",1011.5700v3
+2010-12-21,Characterization of Decoherence from an Environmental Perspective,"For the case of phase damping (pure decoherence) we investigate the extent to
+which environmental traits are imprinted on an open quantum system. The
+dynamics is described using the quantum channel approach. We study what the
+knowledge of the channel may reveal about the nature of its underlying dynamics
+and, conversely, what the dynamics tells us about how to consistently model the
+environment. We find that for a Markov phase-damping channel, that is, a
+channel compatible with a time-continuous Markovian evolution, the environment
+may adequately be represented by a mixture of only a few coherent states. For
+arbitrary Hilbert space dimension $N\geq 4$ we refine the idea of {\it quantum
+phase damping}, of which we show a means of identification. Symmetry
+considerations are used to identify decoherence-free subspaces of the system.",1012.4685v1
+2010-12-28,Quantum Leptogenesis I,"Thermal leptogenesis explains the observed matter-antimatter asymmetry of the
+universe in terms of neutrino masses, consistent with neutrino oscillation
+experiments. We present a full quantum mechanical calculation of the generated
+lepton asymmetry based on Kadanoff-Baym equations. Origin of the asymmetry is
+the departure from equilibrium of the statistical propagator of the heavy
+Majorana neutrino, together with CP violating couplings. The lepton asymmetry
+is calculated directly in terms of Green's functions without referring to
+""number densities"". Compared to Boltzmann and quantum Boltzmann equations, the
+crucial difference are memory effects, rapid oscillations much faster than the
+heavy neutrino equilibration time. These oscillations strongly suppress the
+generated lepton asymmetry, unless the standard model gauge interactions, which
+cause thermal damping, are properly taken into account. We find that these
+damping effects essentially compensate the enhancement due to quantum
+statistical factors, so that finally the conventional Boltzmann equations again
+provide rather accurate predictions for the lepton asymmetry.",1012.5821v3
+2011-01-06,Chemical Enrichment in the Carbon-enhanced Damped Lyman $α$ System,"We show that the recently observed elemental abundance pattern of the
+carbon-rich metal-poor Damped Lyman $\alpha$ (DLA) system is in excellent
+agreement with the nucleosynthesis yields of faint core-collapse supernovae of
+primordial stars. The observed abundance pattern is not consistent with the
+nucleosynthesis yields of pair-instability supernovae. The DLA abundance
+pattern is very similar to that of carbon-rich extremely metal-poor (EMP)
+stars, and the contributions from low-mass stars and/or binary effects should
+be very small in DLAs. This suggests that chemical enrichment by the first
+stars in the first galaxies is driven by core-collapse supernovae from $\sim
+20-50 M_\odot$ stars, and also supports the supernova scenario as the
+enrichment source of EMP stars in the Milky Way Galaxy.",1101.1227v2
+2011-02-08,Quantization of Damping Particle Based On New Variational Principles,"In this paper a new approach is proposed to quantize mechanical systems whose
+equations of motion can not be put into Hamiltonian form. This approach is
+based on a new type of variational principle, which is adopted to a describe a
+relation: a damping particle may shares a common phase curve with a free
+particle, whose Lagrangian in the new variational principle can be considered
+as a Lagrangian density in phase space. According to Feynman's theory, the
+least action principle is adopted to modify the Feynman's path integral
+formula, where Lagrangian is replaced by Lagrangian density. In the case of
+conservative systems, the modification reduces to standard Feynman's propagator
+formula. As an example a particle with friction is analyzed in detail.",1102.1573v2
+2011-02-15,Spin dynamics in the strong spin-orbit coupling regime,"We study the spin dynamics in a high-mobility two dimensional electron gas
+(2DEG) with generic spin-orbit interactions (SOIs). We derive a set of spin
+dynamic equations which capture the purely exponential to the damped
+oscillatory spin evolution modes observed in different regimes of SOI strength.
+Hence we provide a full treatment of the D'yakonov-Perel's mechanism by using
+the microscopic linear response theory from the weak to the strong SOI limit.
+We show that the damped oscillatory modes appear when the electron scattering
+time is larger than half of the spin precession time due to the SOI, in
+agreement with recent observations. We propose a new way to measure the
+scattering time and the relative strength of Rashba and linear Dresselhaus SOIs
+based on these modes and optical grating experiments. We discuss the physical
+interpretation of each of these modes in the context of Rabi oscillation.",1102.3170v1
+2011-03-03,Collective modes and the speed of sound in the Fulde-Ferrell-Larkin-Ovchinnikov state,"We consider the density response of a spin-imbalanced ultracold Fermi gas in
+an optical lattice in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. We
+calculate the collective mode spectrum of the system in the generalised random
+phase approximation and find that though the collective modes are damped even
+at zero tempererature, the damping is weak enough to have well-defined
+collective modes. We calculate the speed of sound in the gas and show that it
+is anisotropic due to the anisotropy of the FFLO pairing, which implies an
+experimental signature for the FFLO state.",1103.0696v2
+2011-03-10,"Shocks in financial markets, price expectation, and damped harmonic oscillators","Using a modified damped harmonic oscillator model equivalent to a model of
+market dynamics with price expectations, we analyze the reaction of financial
+markets to shocks. In order to do this, we gather data from indices of a
+variety of financial markets for the 1987 Black Monday, the Russian crisis of
+1998, the crash after September 11th (2001), and the recent downturn of markets
+due to the subprime mortgage crisis in the USA (2008). Analyzing those data we
+were able to establish the amount by which each market felt the shocks, a
+dampening factor which expresses the capacity of a market of absorving a shock,
+and also a frequency related with volatility after the shock. The results gauge
+the efficiency of different markets in recovering from such shocks, and measure
+some level of dependence between them. We also show, using the correlation
+matrices between the indices used, that financial markets are now much more
+connected than they were two decades ago.",1103.1992v2
+2011-03-22,Inductive determination of the optimum tunnel barrier thickness in magnetic tunnelling junction stacks for spin torque memory applications,"We use pulsed inductive microwave magnetometry to study the precessional
+magnetization dynamics of the free layer in CoFeB/MgO/CoFeB based magnetic
+tunnelling junction stacks with varying MgO barrier thickness. From the field
+dependence of the precession frequency we are able to derive the uniaxial
+anisotropy energy and the exchange coupling between the free and the pinned
+layer. Furthermore the field dependence of the effective damping parameter is
+derived. Below a certain threshold barrier thickness we observe an increased
+effective damping for antiparallel orientation of free and pinned layer which
+would inhibit reversible low current density spin torque magnetization
+reversal. Such inductive measurements, in combination with wafer probe station
+based magneto transport experiments, allow a fast determination of the optimum
+tunnel barrier thickness range for spin torque memory applications in a
+lithography free process.",1103.4248v1
+2011-04-11,Algebraic damping in the one-dimensional Vlasov equation,"We investigate the asymptotic behavior of a perturbation around a spatially
+non homogeneous stable stationary state of a one-dimensional Vlasov equation.
+Under general hypotheses, after transient exponential Landau damping, a
+perturbation evolving according to the linearized Vlasov equation decays
+algebraically with the exponent -2 and a well defined frequency. The
+theoretical results are successfully tested against numerical $N$-body
+simulations, corresponding to the full Vlasov dynamics in the large $N$ limit,
+in the case of the Hamiltonian mean-field model. For this purpose, we use a
+weighted particles code, which allows us to reduce finite size fluctuations and
+to observe the asymptotic decay in the $N$-body simulations.",1104.1890v2
+2011-05-06,System-environment dynamics of X-type states in noninertial frames,"The system-environment dynamics of noninertial systems is investigated. It is
+shown that for the amplitude damping channel: (i) the biggest difference
+between the decoherence effect and the Unruh radiation on the dynamics of the
+entanglement is the former only leads to entanglement transfer in the whole
+system, but the latter damages all types of entanglement; (ii) the
+system-environment entanglement increases and then declines, while the
+environment-environment entanglement always increases as the decay parameter
+$p$ increases; and (iii) the thermal fields generated by the Unruh effect can
+promote the sudden death of entanglement between the subsystems while postpone
+the sudden birth of entanglement between the environments. It is also found
+that there is no system-environment and environment-environment entanglements
+when the system coupled with the phase damping environment.",1105.1216v2
+2011-05-10,Spontaneous magnon decays in planar ferromagnet,"We predict that spin-waves in an easy-plane ferromagnet have a finite
+lifetime at zero temperature due to spontaneous decays. In zero field the
+damping is determined by three-magnon decay processes, whereas decays in the
+two-particle channel dominate in a transverse magnetic field. Explicit
+calculations of the magnon damping are performed in the framework of the
+spin-wave theory for the $XXZ$ square-lattice ferromagnet with an anisotropy
+parameter $\lambda<1$. In zero magnetic field the decays occur for
+$\lambda^*<\lambda<1$ with $\lambda^*\approx 1/7$. We also discuss possibility
+of experimental observation of the predicted effect in a number of
+ferromagnetic insulators.",1105.1893v1
+2011-05-19,"Scaling of the higher-order flow harmonics: implications for initial-eccentricity models and the ""viscous horizon""","The scaling properties of the flow harmonics for charged hadrons $v_{n}$ and
+their ratios $[ v_n/(v_2)^{n/2}]_{n\geq 3}$, are studied for a broad range of
+transverse momenta ($p_T$) and centrality selections in Au+Au and Pb+Pb
+collisions at $\sqrt{s_{NN}}=0.2 \text{and} 2.76$ TeV respectively. At
+relatively low $p_T$, these scaling properties are found to be compatible with
+the expected growth of viscous damping for sound propagation in the plasma
+produced in these collisions. They also provide important constraints for
+distinguishing between the two leading models of collision eccentricities, as
+well as a route to constrain the relaxation time and make estimates for the
+ratio of viscosity to entropy density $\eta/s$, and the ""viscous horizon"" or
+length-scale which characterizes the highest harmonic which survives viscous
+damping.",1105.3782v2
+2011-05-26,Dynamics in the production of superheavy nuclei in low-energy heavy-ion collisions,"We present a review of the recent progress of theoretical models on the
+description of the formation of superheavy nuclei in collisions of heavy
+systems. Two sorts of reactions that are the fusion-evaporation mechanism and
+the massive damped collisions to produce superheavy nuclei are discussed.
+Problems and further improvements of the capture of colliding partners, the
+formation of compound nucleus and the de-excitation process are pointed out.
+Possible combinations in the synthesis of the gap of the cold fusion and
+$^{48}$Ca induced reactions are proposed by the calculations based on the
+dinuclear system model and also compared with other approaches. The synthesis
+of neutron-rich heavy isotopes near sub-shell closure N=162 via transfer
+reactions in the damped collisions of two actinides and the influence of shell
+closure on the production of heavy isotopes are investigated. Prospective
+possibility to reach superheavy nuclei near N=184 via neutron-rich radioactive
+beams of high intensity in the future is discussed.",1105.5224v2
+2011-06-01,Effect of detuning on the phonon induced dephasing of optically driven InGaAs/GaAs quantum dots,"Recently, longitudinal acoustic phonons have been identified as the main
+source of the intensity damping observed in Rabi rotation measurements of the
+ground-state exciton of a single InAs/GaAs quantum dot. Here we report
+experiments of intensity damped Rabi rotations in the case of detuned laser
+pulses, the results have implications for the coherent optical control of both
+excitons and spins using detuned laser pulses.",1106.0142v1
+2011-06-09,Investigating viscous damping using a webcam,"We describe an experiment involving a mass oscillating in a viscous fluid and
+analyze viscous damping of harmonic motion. The mechanical oscillator is
+tracked using a simple webcam and an image processing algorithm records the
+position of the geometrical center as a function of time. Interesting
+information can be extracted from the displacement-time graphs, in particular
+for the underdamped case. For example, we use these oscillations to determine
+the viscosity of the fluid. Our mean value of 1.08 \pm 0.07 mPa s for distilled
+water is in good agreement with the accepted value at 20\circC. This experiment
+has been successfully employed in the freshman lab setting.",1106.1823v1
+2011-06-11,Conformal and covariant formulation of the Z4 system with constraint-violation damping,"We present a new formulation of the Einstein equations based on a conformal
+and traceless decomposition of the covariant form of the Z4 system. This
+formulation combines the advantages of a conformal decomposition, such as the
+one used in the BSSNOK formulation (i.e. well-tested hyperbolic gauges, no need
+for excision, robustness to imperfect boundary conditions) with the advantages
+of a constraint-damped formulation, such as the generalized harmonic one (i.e.
+exponential decay of constraint violations when these are produced). We
+validate the new set of equations through standard tests and by evolving binary
+black hole systems. Overall, the new conformal formulation leads to a better
+behavior of the constraint equations and a rapid suppression of the violations
+when they occur. The changes necessary to implement the new conformal
+formulation in standard BSSNOK codes are very small as are the additional
+computational costs.",1106.2254v2
+2011-06-14,"Oscillations of hot, young neutron stars: Gravitational wave frequencies and damping times","We study how the frequencies and damping times of oscillations of a newly
+born, hot proto-neutron star depend on the physical quantities which
+characterize the star quasi-stationary evolution which follows the bounce.
+Stellar configurations are modeled using a microscopic equation of state
+obtained within the Brueckner-Hartree-Fock, nuclear many-body approach,
+extended to the finite-temperature regime. We discuss the mode frequency
+behaviour as function of the lepton composition, and of the entropy gradients
+which prevail in the interior of the star. We find that, in the very early
+stages, gravitational wave emission efficiently competes with neutrino
+processes in dissipating the star mechanical energy residual of the
+gravitational collapse.",1106.2736v1
+2011-06-22,Samll BGK waves and nonlinear Landau damping (higher dimensions),"Consider Vlasov-Poisson system with a fixed ion background and periodic
+condition on the space variables, in any dimension d\geq2. First, we show that
+for general homogeneous equilibrium and any periodic x-box, within any small
+neighborhood in the Sobolev space W_{x,v}^{s,p} (p>1,s<1+(1/p)) of the steady
+distribution function, there exist nontrivial travelling wave solutions (BGK
+waves) with arbitrary traveling speed. This implies that nonlinear Landau
+damping is not true in W^{s,p}(s<1+(1/p)) space for any homogeneous equilibria
+and in any period box. The BGK waves constructed are one dimensional, that is,
+depending only on one space variable. Higher dimensional BGK waves are shown to
+not exist. Second, for homogeneous equilibria satisfying Penrose's linear
+stability condition, we prove that there exist no nontrivial invariant
+structures in the (1+|v|^{2})^{b}-weighted H_{x,v}^{s} (b>((d-1)/4), s>(3/2))
+neighborhood. Since arbitrarilly small BGK waves can also be constructed near
+any homogeneous equilibria in such weighted H_{x,v}^{s} (s<(3/2)) norm, this
+shows that s=(3/2) is the critical regularity for the existence of nontrivial
+invariant structures near stable homogeneous equilibria. These generalize our
+previous results in the one dimensional case.",1106.4368v1
+2011-07-13,Dimension of attractors and invariant sets of damped wave equations in unbounded domains,"Under fairly general assumptions, we prove that every compact invariant set
+$\mathcal I$ of the semiflow generated by the semilinear damped wave equation
+u_{tt}+\alpha u_t+\beta(x)u-\Deltau = f(x,u), (t,x)\in[0,+\infty[\times\Omega,
+u = 0, (t,x)\in[0,+\infty[\times\partial\Omega in $H^1_0(\Omega)\times
+L^2(\Omega) has finite Hausdorff and fractal dimension. Here $\Omega$ is a
+regular, possibly unbounded, domain in $\R^3$ and $f(x,u)$ is a nonlinearity of
+critical growth. The nonlinearity $f(x,u)$ needs not to satisfy any
+dissipativeness assumption and the invariant subset $\mathcal I$ needs not to
+be an attractor. If $f(x,u)$ is dissipative and $\mathcal I$ is the global
+attractor, we give an explicit bound on the Hausdorff and fractal dimension of
+$\mathcal I$ in terms of the structure parameters of the equation.",1107.2589v1
+2011-07-15,K-shell photoionization of Nickel ions using R-matrix,"We present R-matrix calculations of photoabsorption and photoionization cross
+sections across the K edge of the Li-like to Ca-like ions stages of Ni.
+Level-resolved, Breit-Pauli calculations were performed for the Li-like to
+Na-like stages. Term-resolved calculations, which include the mass-velocity and
+Darwin relativistic corrections, were performed for the Mg-like to Ca-like ion
+stages. This data set is extended up to Fe-like Ni using the distorted wave
+approximation as implemented by AUTOSTRUCTURE. The R-matrix calculations
+include the effects of radiative and Auger dampings by means of an optical
+potential. The damping processes affect the absorption resonances converging to
+the K thresholds causing them to display symmetric profiles of constant width
+that smear the otherwise sharp edge at the K-shell photoionization threshold.
+These data are important for the modeling of features found in photoionized
+plasmas.",1107.3146v1
+2011-07-20,Bayesian Magnetohydrodynamic Seismology of Coronal Loops,"We perform a Bayesian parameter inference in the context of resonantly damped
+transverse coronal loop oscillations. The forward problem is solved in terms of
+parametric results for kink waves in one-dimensional flux tubes in the thin
+tube and thin boundary approximations. For the inverse problem, we adopt a
+Bayesian approach to infer the most probable values of the relevant parameters,
+for given observed periods and damping times, and to extract their confidence
+levels. The posterior probability distribution functions are obtained by means
+of Markov Chain Monte Carlo simulations, incorporating observed uncertainties
+in a consistent manner. We find well localized solutions in the posterior
+probability distribution functions for two of the three parameters of interest,
+namely the Alfven travel time and the transverse inhomogeneity length-scale.
+The obtained estimates for the Alfven travel time are consistent with previous
+inversion results, but the method enables us to additionally constrain the
+transverse inhomogeneity length-scale and to estimate real error bars for each
+parameter. When observational estimates for the density contrast are used, the
+method enables us to fully constrain the three parameters of interest. These
+results can serve to improve our current estimates of unknown physical
+parameters in coronal loops and to test the assumed theoretical model.",1107.3943v1
+2011-07-31,Evolution of cat states in a dissipative parametric amplifier: decoherence and entanglement,"The evolution of the Schr\""{o}dinger-cat states in a dissipative parametric
+amplifier is examined. The main tool in the analysis is the normally ordered
+characteristic function. Squeezing, photon-number distribution and reduced
+factorial moments are discussed for the single- and compound-mode cases. Also
+the single-mode Wigner function is demonstrated. In addition to the decoherence
+resulting from the interaction with the environment (damped case) there are two
+sources which can cause such decoherence in the system even if it is completely
+isolated: these are the decay of the pump and the relative phases of the
+initial cat states. Furthermore, for the damped case there are two regimes,
+which are underdamped and overdamped. In the first (second) regime the signal
+mode or the idler mode ""collapses"" to a statistical mixture (thermal field).",1108.0127v1
+2011-07-31,"Second-Order, Dissipative Tâtonnement: Economic Interpretation and 2-Point Limit Cycles","This paper proposes an alternative to the classical price-adjustment
+mechanism (called ""t\^{a}tonnement"" after Walras) that is second-order in time.
+The proposed mechanism, an analogue to the damped harmonic oscillator, provides
+a dynamic equilibration process that depends only on local information. We show
+how such a process can result from simple behavioural rules. The discrete-time
+form of the model can result in two-step limit cycles, but as the distance
+covered by the cycle depends on the size of the damping, the proposed mechanism
+can lead to both highly unstable and relatively stable behaviour, as observed
+in real economies.",1108.0188v3
+2011-08-10,Critical exponents of steady-state phase transitions in fermionic lattice models,"We discuss reservoir induced phase transitions of lattice fermions in the
+non-equilibrium steady state (NESS) of an open system with local reservoirs.
+These systems may become critical in the sense of a diverging correlation
+length upon changing the reservoir coupling. We here show that the transition
+to a critical state is associated with a vanishing gap in the damping spectrum.
+It is shown that although in linear systems there can be a transition to a
+critical state there is no reservoir-induced quantum phase transition between
+distinct phases with non-vanishing damping gap. We derive the static and
+dynamical critical exponents corresponding to the transition to a critical
+state and show that their possible values, defining universality classes of
+reservoir-induced phase transitions are determined by the coupling range of the
+independent local reservoirs. If a reservoir couples to N neighboring lattice
+sites, the critical exponent can assume all fractions from 1 to 1/(N - 1).",1108.2263v5
+2011-09-09,Observation of Spontaneous Brillouin Cooling,"While radiation-pressure cooling is well known, the Brillouin scattering of
+light from sound is considered an acousto-optical amplification-only process.
+It was suggested that cooling could be possible in multi-resonance Brillouin
+systems when phonons experience lower damping than light. However, this regime
+was not accessible in traditional Brillouin systems since backscattering
+enforces high acoustical frequencies associated with high mechanical damping.
+Recently, forward Brillouin scattering in microcavities has allowed access to
+low-frequency acoustical modes where mechanical dissipation is lower than
+optical dissipation, in accordance with the requirements for cooling. Here we
+experimentally demonstrate cooling via such a forward Brillouin process in a
+microresonator. We show two regimes of operation for the Brillouin process:
+acoustical amplification as is traditional, but also for the first time, a
+Brillouin cooling regime. Cooling is mediated by an optical pump, and scattered
+light, that beat and electrostrictively attenuate the Brownian motion of the
+mechanical mode.",1109.2084v2
+2011-09-14,Oscillations of simple networks,"To describe the flow of a miscible quantity on a network, we introduce the
+graph wave equation where the standard continuous Laplacian is replaced by the
+graph Laplacian. This is a natural description of an array of inductances and
+capacities, of fluid flow in a network of ducts and of a system of masses and
+springs. The structure of the graph influences strongly the dynamics which is
+naturally described using the basis of the eigenvectors. In particular, we show
+that if two outer nodes are connected to a common third node with the same
+coupling, then this coupling is an eigenvalue of the Laplacian. Assuming the
+graph is forced and damped at specific nodes, we derive the amplitude
+equations. These are analyzed for two simple non trivial networks: a tree and a
+graph with a cycle. Forcing the network at a resonant frequency reveals that
+damping can be ineffective if applied to the wrong node, leading to a
+disastrous resonance and destruction of the network. These results could be
+useful for complex physical networks and engineering networks like power grids.",1109.3071v2
+2011-09-21,High-order explicit local time-stepping methods for damped wave equations,"Locally refined meshes impose severe stability constraints on explicit
+time-stepping methods for the numerical simulation of time dependent wave
+phenomena. Local time-stepping methods overcome that bottleneck by using
+smaller time-steps precisely where the smallest elements in the mesh are
+located. Starting from classical Adams-Bashforth multi-step methods, local
+time-stepping methods of arbitrarily high order of accuracy are derived for
+damped wave equations. When combined with a finite element discretization in
+space with an essentially diagonal mass matrix, the resulting time-marching
+schemes are fully explicit and thus inherently parallel. Numerical experiments
+with continuous and discontinuous Galerkin finite element discretizations
+validate the theory and illustrate the usefulness of these local time-stepping
+methods.",1109.4480v2
+2011-09-21,Anisotropic critical magnetic fluctuations in the ferromagnetic superconductor UCoGe,"We report neutron scattering measurements of critical magnetic excitations in
+the weakly ferromagnetic superconductor UCoGe. The strong non-Landau damping of
+the excitations we observe, although unusual has been found in another related
+ferromagnet, UGe2 at zero pressure. However, we also find there is a
+significant anisotropy of the magnetic correlation length in UCoGe that
+contrasts with an almost isotropic length for UGe2. The values of the magnetic
+correlation length and damping are found to be compatible with
+superconductivity on small Fermi surface pockets. The anisotropy may be
+important to explain why UCoGe is a superconductor at zero pressure while UGe2
+is not.",1109.4541v1
+2011-09-30,"PT-symmetry, indefinite damping and dissipation-induced instabilities","With perfectly balanced gain and loss, dynamical systems with indefinite
+damping can obey the exact PT-symmetry being marginally stable with a pure
+imaginary spectrum. At an exceptional point where the symmetry is spontaneously
+broken, the stability is lost via passing through a non-semisimple 1:1
+resonance. In the parameter space of a general dissipative system, marginally
+stable PT-symmetric ones occupy singularities on the boundary of the asymptotic
+stability. To observe how the singular surface governs dissipation-induced
+destabilization of the PT-symmetric system when gain and loss are not matched,
+an extension of recent experiments with PT-symmetric LRC circuits is proposed.",1110.0018v2
+2011-10-01,Electrical measurement of antivortex wall eigenfrequency,"The dynamics of a ferromagnetic antivortex wall has been experimentally
+studied in a magnetic nanostructure. Two different techniques have been used to
+independently measure the eigenfrequency of an antivortex wall such as the
+resonance excitation by sinusoidal microwave and the damped resonance
+excitation induced by short voltage pulses. Direct observation of antivortex
+wall nucleation has been measured in the frequency domain for the first time.
+Electrical measurements of the antivortex dynamics in frequency domain reveal
+the existence of multi-eigenmodes as well as nonlinear behaviors for large
+excitation amplitudes. The time resolved measurements of the antivortex wall
+show that the frequency of the damped gyration is similar to that of frequency
+domain and coexistence of spin wave excitations.",1110.0113v1
+2011-10-06,Comparative Wakefield Analysis of a First Prototype of a DDS Structure for CLIC Main Linac,"A Damped Detuned Structure (DDS) for CLIC main linac has been proposed as an
+alternative to the present baseline design which is based on heavy damping. A
+first prototype, CLIC_DDS_A, for high power tests has been already designed and
+is under construction. It is also foreseen to design a further prototype,
+CLIC_DDS_B, to test both the wakefield suppression and high power performances.
+Wakefield calculations for DDS are, in the early design stage, based on single
+infinitely periodic cells. Though cell-to-cell interaction is taken into
+account to calculate the wakefields, it is important to study full structure
+properties using computational tools. In particular this is fundamental for
+defining the input parameters for the HOM coupler that is crucial for the
+performances of DDS. In the following a full analysis of wakefields and
+impedances based on simulations conducted with finite difference based
+electromagnetic computer code GdfidL will be presented.",1110.1207v1